thromboxane-a2 and Inflammation

Platelets play a central role in inflammation through their direct interaction with other cell types, such as leucocytes and endothelial cells, and by the release of many factors, that is, lipids [such as thromboxane (TX)A2 ] and proteins (a wide number of angiogenic and growth factors) stored in α-granules, and adenosine diphosphate (ADP), stored in dense granules. These platelet actions trigger autocrine and paracrine activation processes that lead to leucocyte recruitment into different tissues and phenotypic changes in stromal cells which contribute to the development of different disease states, such as atherosclerosis and atherothrombosis, intestinal inflammation and cancer. The signals induced by platelets may cause pro-inflammatory and malignant phenotypes in other cells through the persistent induction of aberrant expression of cyclooxygenase (COX)-2 and increased generation of prostanoids, mainly prostaglandin (PG)E2 . In addition to cardiovascular disease, enhanced platelet activation has been detected in inflammatory disease and intestinal tumourigenesis. Moreover, the results of clinical studies have shown that the antiplatelet drug aspirin reduces the incidence of vascular events and colorectal cancer. All these pieces of evidence support the notion that colorectal cancer and atherothrombosis may share a common mechanism of disease, that is, platelet activation in response to epithelial (in tumourigenesis) and endothelial (in tumourigenesis and atherothrombosis) injury. Extensive translational medicine research is necessary to obtain a definitive mechanistic demonstration of the platelet-mediated hypothesis of colon tumourigenesis. The results of these studies will be fundamental to support the clinical decision to recommend the use of low-dose aspirin, and possibly other antiplatelet agents, in primary prevention, that is, even for individuals at low cardiovascular risk.

Topics: Animals; Aspirin; Blood Platelets; Cardiovascular Diseases; Colorectal Neoplasms; Cyclooxygenase 2; Disease Models, Animal; Endothelial Cells; Humans; Inflammation; Leukocytes; Neoplasms; Platelet Activation; Platelet Aggregation Inhibitors; Stromal Cells; Thromboxane A2; Up-Regulation

Patients with rheumatoid arthritis (RA) appear to be at a higher risk of lung cancer (LC). Although the connection between RA and LC has been an active area of research for many years, the molecular pathogenesis of the disease process remains unclear. The cyclooxygenase (COX)-2/thromboxane A2 (TxA2) pathway has been shown to play a potential role in LC development through an auto-regulatory feedback loop. An increased level of TxA2 has been found in RA patients, and intriguingly, the positive feedback loop for the COX-2/TxA2 pathway was shown to have a potential function in RA fibroblast-like synoviocytes (RA-FLS). Thus, the molecular basis of LC development in patients with RA has been at least in partly described. It is possible that COX-2-derived TxA2 could be monitored for the early detection of LC in RA patients, and targeting this molecular pathway may decrease the risk of LC in patients with RA.

Topics: Arthritis, Rheumatoid; Cyclooxygenase 2; Fibroblasts; Gene Expression Profiling; Gene Expression Regulation, Enzymologic; Gene Expression Regulation, Neoplastic; Humans; Inflammation; Lung Neoplasms; Synovial Fluid; Thromboxane A2

Mild to moderate hypothermia (32-35 degrees C) is the first treatment with proven efficacy for postischemic neurological injury. In recent years important insights have been gained into the mechanisms underlying hypothermia's protective effects; in addition, physiological and pathophysiological changes associated with cooling have become better understood.. To discuss hypothermia's mechanisms of action, to review (patho)physiological changes associated with cooling, and to discuss potential side effects.. Review article.. None.. A myriad of destructive processes unfold in injured tissue following ischemia-reperfusion. These include excitotoxicty, neuroinflammation, apoptosis, free radical production, seizure activity, blood-brain barrier disruption, blood vessel leakage, cerebral thermopooling, and numerous others. The severity of this destructive cascade determines whether injured cells will survive or die. Hypothermia can inhibit or mitigate all of these mechanisms, while stimulating protective systems such as early gene activation. Hypothermia is also effective in mitigating intracranial hypertension and reducing brain edema. Side effects include immunosuppression with increased infection risk, cold diuresis and hypovolemia, electrolyte disorders, insulin resistance, impaired drug clearance, and mild coagulopathy. Targeted interventions are required to effectively manage these side effects. Hypothermia does not decrease myocardial contractility or induce hypotension if hypovolemia is corrected, and preliminary evidence suggests that it can be safely used in patients with cardiac shock. Cardiac output will decrease due to hypothermia-induced bradycardia, but given that metabolic rate also decreases the balance between supply and demand, is usually maintained or improved. In contrast to deep hypothermia (

Topics: Acidosis; Apoptosis; Body Temperature Regulation; Brain Edema; Brain Ischemia; Calpain; Critical Care; Epilepsy; Free Radicals; Genes, Immediate-Early; Humans; Hypothermia, Induced; Infections; Inflammation; Ion Pumps; Mitochondria; Reperfusion Injury; Thrombosis; Thromboxane A2

Thrombosis, both venous and arterial, is a major cause of morbidity and mortality worldwide. Consequently, there is an ongoing search for new antithrombotic drugs, particularly novel antiplatelet agents and anticoagulants. A better understanding of the biochemical pathways involved in platelet activation and coagulation and of the links between these systems and the impact of thrombosis on inflammation has led to the identification of new targets for antithrombotic drugs. This paper focuses on these new targets and new antiplatelet drugs and anticoagulants and describes the major advances in the continuing search for more potent antithrombotic drugs that have limited effects on hemostasis.

Topics: Animals; Anticoagulants; Antithrombin III; Drug Design; Fibrinolytic Agents; Health Services Needs and Demand; Humans; Inflammation; Phosphodiesterase Inhibitors; Platelet Aggregation Inhibitors; Purinergic P2 Receptor Antagonists; Receptor, PAR-1; Receptors, Purinergic P2Y12; Thrombin; Thromboxane A2; Vitamin K

Atherosclerosis is a chronic and progressive inflammatory vascular disease that is characterized by a complex interplay between some components of the bloodstream and the arterial wall. The lipid derivatives eicosanoids have been identified as important mediators that contribute to mechanisms of atherogenesis. Prostaglandins and thromboxane A2 are members of the eicosanoid family synthesized from arachidonic acid by the combined action of cyclooxygenases and prostaglandins and thromboxane A2 synthase. Thromboxane A2, a potent platelet activator and vasoconstrictor and prostacyclin, a platelet inhibitor and vasodilator, are the most important in the development of cardiovascular diseases. Several pro-atherogenic biological effects have also been attributed to isoprostanes, a class of eicosanoid isomers formed via a free radical-mediated oxidation of fatty acids esterified in membrane phospholipids. Both groups of lipids manifest their biological activities by binding to specific receptors in target cells. In this article, we will describe the biological roles of prostacyclin, thromboxane A2 and isoprostanes in atherogenesis and discuss the latest pharmacological studies assessing the therapeutic effects of drugs that specifically target their biosynthesis and/or biological activities on vascular inflammation and atherosclerotic lesion development.

Topics: Animals; Atherosclerosis; Cardiovascular Agents; Cyclooxygenase Inhibitors; Drug Delivery Systems; Eicosanoids; Epoprostenol; Humans; Inflammation; Isoprostanes; Thromboxane A2

Historically, anti-inflammatory drugs had their origins in the serendipitous discovery of certain plants and their extracts being applied for the relief of pain, fever and inflammation. When salicylates were discovered in the mid-19th century to be the active components of Willow Spp., this enabled these compounds to be synthesized and from this, acetyl-salicylic acid or Aspirin was developed. Likewise, the chemical advances of the 19th-20th centuries lead to development of the non-steroidal anti-inflammatory drugs (NSAIDs), most of which were initially organic acids, but later non-acidic compounds were discovered. There were two periods of NSAID drug discovery post-World War 2, the period up to the 1970's which was the pre-prostaglandin period and thereafter up to the latter part of the last century in which their effects on prostaglandin production formed part of the screening in the drug-discovery process. Those drugs developed up to the 1980-late 90's were largely discovered empirically following screening for anti-inflammatory, analgesic and antipyretic activities in laboratory animal models. Some were successfully developed that showed low incidence of gastro-intestinal (GI) side effects (the principal adverse reaction seen with NSAIDs) than seen with their predecessors (e.g. aspirin, indomethacin, phenylbutazone); the GI reactions being detected and screened out in animal assays. In the 1990's an important discovery was made from elegant molecular and cellular biological studies that there are two cyclo-oxygenase (COX) enzyme systems controlling the production of prostanoids [prostaglandins (PGs) and thromboxane (TxA2)]; COX-1 that produces PGs and TxA2 that regulate gastrointestinal, renal, vascular and other physiological functions, and COX-2 that regulates production of PGs involved in inflammation, pain and fever. The stage was set in the 1990's for the discovery and development of drugs to selectively control COX-2 and spare the COX-1 that is central to physiological processes whose inhibition was considered a major factor in development of adverse reactions, including those in the GI tract. At the turn of this century, there was enormous commercial development following the introduction of two new highly selective COX-2 inhibitors, known as coxibs (celecoxib and rofecoxib) which were claimed to have low GI side effects. While found to have fulfilled these aims in part, an alarming turn of events took place in the late 2004 period when rofecox

Topics: Animals; Anti-Inflammatory Agents, Non-Steroidal; Cardiovascular Diseases; Cyclooxygenase 1; Cyclooxygenase 2; Cyclooxygenase 2 Inhibitors; Cytokines; Digestive System Diseases; Disease Models, Animal; Drug Delivery Systems; Drug Design; Fever; History, 19th Century; History, 20th Century; History, 21st Century; Humans; Inflammation; Isoenzymes; Neoplasms; Neurodegenerative Diseases; Pain; Prostaglandins; Signal Transduction; Stroke; Thromboxane A2

Acute rejection of a transplanted organ is characterized by intense inflammation within the graft. Yet, for many years transplant researchers have overlooked the role of classic mediators of inflammation such as prostaglandins and thromboxane (prostanoids) in alloimmune responses. It has been demonstrated that local production of prostanoids within the allograft is increased during an episode of acute rejection and that these molecules are able to interfere with graft function by modulating vascular tone, capillary permeability, and platelet aggregation. Experimental data also suggest that prostanoids may participate in alloimmune responses by directly modulating T lymphocyte and antigen-presenting cell function. In the present paper, we provide a brief overview of the alloimmune response, of prostanoid biology, and discuss the available evidence for the role of prostaglandin E2 and thromboxane A2 in graft rejection.

Topics: Acute Disease; Dinoprostone; Graft Rejection; Humans; Inflammation; Inflammation Mediators; Prostaglandins; Thromboxane A2

The actions of prostanoids in various physiological and pathophysiological conditions have been being examined using mice lacking different prostanoid receptors. Prostaglandin (PG) I2 worked not only as a mediator of inflammation but also as an antithrombotic agent. PGF2alpha was found to be an essential inducer of labor. Several important actions of PGE2 are exerted via each of the four PGE2 receptor subtypes: EP1, EP2, EP3 and EP4. PGE2 participated in colon carcinogenesis via the EP1. PGE2 also participates in ovulation and fertilization and contributes to the control of blood pressure under high-salt intake via the EP2. PGE2 worked as a mediator of febrile responses to both endogenous and exogenous pyrogens and as a regulator of bicarbonate secretion induced by acid-stimulation in the duodenum via the EP3. It regulated the closure of ductus arteriosus and showed bone resorbing action via the EP4. PGD2 was found to be a mediator of allergic asthma. These studies have revealed important roles of prostanoids, some of which had not previously been known.

Topics: Animals; Asthma; Bicarbonates; Colonic Neoplasms; Dinoprost; Dinoprostone; Female; Fever; Hypertension; Inflammation; Labor, Obstetric; Mice; Mice, Knockout; Pregnancy; Prostaglandins; Receptors, Prostaglandin; Reproduction; Thrombosis; Thromboxane A2

Deposition of immune complexes in tissues is the pathogenic mechanism underlying tissue injury in a number of diverse clinical conditions affecting the skin, joints, blood vessels and renal glomeruli. Initial approaches to the understanding of these conditions have stressed the roles of both the activation of the complement system and the accumulation of polymorphonuclear leukocytes as the main molecular and cellular mechanisms explaining the sequence of events leading to tissue damage. Recent findings on (i) the molecular biology of the leukocyte chemoattractants, (ii) the chemical structure and function of receptors for the Fc portion of the antibody molecule and (iii) the signaling events coupled to the engagement of these receptors have led to an understanding of the biochemical events involved in immune-complex injury and have provided a promising avenue for the development of therapeutic approaches. This review will focus on our current understanding of signal transduction events in the effector phase of immune-complex-mediated tissue injury.

Topics: Anaphylatoxins; Animals; Calcium-Calmodulin-Dependent Protein Kinases; Chemokines; Chemotactic Factors; Dinoprostone; GTP-Binding Proteins; Immunoglobulin G; Inflammation; Leukocytes; Leukotriene B4; Leukotrienes; Lipids; Mice; Models, Biological; NF-kappa B; Phagocytes; Phospholipases A; Platelet Activating Factor; Signal Transduction; Thromboxane A2

Topics: Animals; Hematopoiesis; Humans; Inflammation; Interleukin-1; Macrophages; Prostaglandins; Thromboxane A2

Urinary i-TXB2 of renal transplant patients was found to be unaffected by CsA administration. Thus CsA treatment is unlikely to contribute to false positive values in this diagnostic indicator of rejection. It is possible that CsA treatment may suppress the peak i-TXB2 attending rejection but this does not seem to be the case. Studies on rats with cardiac allografts show CsA not to attenuate the rejection i-TXB2 peak (8). The causal role of thromboxane in transplant rejection was further amplified by experimental studies in rats where the cardiac allograft was protected by thromboxane synthase inhibitors and receptor antagonists. The inflammatory cell infiltrate of clinical renal allografts correlated with urine i-TXB2. These data strengthens the diagnostic value of urine i-TXB2 as a non invasive indicator of transplant rejection. Serum gamma-interferon was studied in nine patients and detected for 14 and 10 consecutive days, respectively in 2 patients. Three of the remaining patients had mild rejection episodes. Of the two patients one rejected the kidney and the other had CMV infection. No correlation was found between gamma-interferon and urine-TXB2. Thus elevated serum gamma-interferon does not interfere with urine i-TXB2.

Topics: Animals; Biopsy, Needle; Fatty Acids, Unsaturated; Graft Rejection; Humans; Inflammation; Interferon-gamma; Kidney; Kidney Transplantation; Lymphocyte Activation; Lymphocytes; Thromboxane A2; Thromboxane B2; Transplantation, Homologous

Topics: Animals; Arachidonate 5-Lipoxygenase; Humans; Immune System; In Vitro Techniques; Inflammation; Leukocytes; Leukotriene B4; Prostaglandins; SRS-A; Thromboxane A2

Topics: Animals; Arachidonic Acid; Arachidonic Acids; Hemodynamics; Humans; Inflammation; Leukocytes; Prostaglandins; Thromboxane A2

A problem of leukotrienes--metabolites of arachidonic acid is reviewed in immunological aspects. Their nomenclature is given; basic pathways of biosynthesis, transformation and mode of leukotriens participation in hypersensitivity and inflammatory reactions are considered. The possibility of application of leukotrienes antagonists and inhibitors of their formation for allergic diseases treatment is discussed.

Topics: Animals; Antigens; Arachidonic Acids; Drug Synergism; Guinea Pigs; Humans; Hypersensitivity; Inflammation; Leukotriene B4; Neurotransmitter Agents; Rabbits; Receptors, Immunologic; SRS-A; Structure-Activity Relationship; Terminology as Topic; Thromboxane A2

Topics: Animals; Arachidonic Acids; Chemotaxis, Leukocyte; Chromones; Dogs; Guinea Pigs; Humans; Hypertension, Pulmonary; Inflammation; Ketanserin; Leukocyte Count; Leukocytes; Lung; Piperidines; Platelet Activating Factor; Pulmonary Embolism; Respiratory Distress Syndrome; Serotonin; Serotonin Antagonists; SRS-A; Thromboxane A2

Topics: Animals; Cardiovascular System; Cyclic AMP; Digestive System; Epoprostenol; Humans; Inflammation; Kidney; Lung; Platelet Aggregation; Prostaglandins; Thromboxane A2; Thromboxanes

Topics: Animals; Arachidonic Acids; Blood Platelets; Cardiopulmonary Bypass; Cyclooxygenase Inhibitors; Epoprostenol; Female; Hemostasis; Humans; Inflammation; Lung; Platelet Aggregation; Prostaglandin Endoperoxides; Prostaglandins; Thrombosis; Thromboxane A2; Uterus; Vasodilator Agents

Topics: Animals; Anti-Inflammatory Agents; Arachidonic Acids; Enzyme Inhibitors; Epoprostenol; Guinea Pigs; Humans; Hydroxy Acids; Inflammation; Lipoxygenase; Lipoxygenase Inhibitors; Prostaglandins; Thromboxane A2

Topics: Arachidonic Acids; Aspirin; Cell Division; Cell Separation; Epoprostenol; Immunity, Cellular; Indomethacin; Inflammation; Lymphocytes; Lymphokines; Macrophages; Prostaglandins; Prostaglandins E; Thromboxane A2

Topics: Anaphylaxis; Animals; Arachidonic Acids; Cyclooxygenase Inhibitors; Digestive System; Epoprostenol; Fatty Acids; Humans; Inflammation; Prostaglandin Endoperoxides; Prostaglandins; Thromboxane A2; Thromboxane-A Synthase; Thromboxanes

Topics: Animals; Anti-Inflammatory Agents; Arachidonic Acids; Fever; Humans; Inflammation; Prostaglandin Endoperoxides; Prostaglandins; Thromboxane A2

Barrett's esophagus (BE), a complication of gastroesophageal reflux disease (GERD), predisposes patients to esophageal adenocarcinoma (EAC). Reliable biomarkers for early detection and discovery of potential drug targets are urgently needed for improved BE and EAC patient outcomes.. Patient biopsy samples were evaluated for COX1/2, and thromboxane A2 synthase (TBXAS) expression. Circulating prostaglandins biosynthesis was determined using enzyme immunoassay kits. Anchorage-independent cell growth assay, crystal violet staining assay, and xenograft experiments were conducted to assess BE and EAC cell growth. A surgical mouse model of reflux (i.e., esophagoduodenostomy) was established and samples were analyzed using an enzyme immunoassay kit, immunohistochemistry, immunoblotting, or RT-PCR. Esophageal biopsy samples (pre- and post-intervention) were obtained from a randomized clinical trial in which participants were administered esomeprazole (40 mg) twice daily in combination with an acetylsalicylic acid (ASA) placebo or 81 or 325 mg ASA for 28 days. Esophageal biopsy specimens before and after the intervention period were analyzed.. COX2 and TBXAS are highly expressed in BE and EAC patients accompanied by a pronounced elevation of circulating TXA2 levels. ASA suppressed BE and EAC growth by targeting the TXA2 pathway. Additionally, biopsies from 49 patients (with similar baseline characteristics) showed that ASA substantially decreased serum TXA2 levels, resulting in reduced inflammation.. This study establishes the importance of the COX1/2-driven TXA2 pathway in BE and EAC pathophysiology and lays the groundwork for introducing a TXA2-targeting strategy for EAC prevention and early detection.. Hormel Foundation, Exact Sciences, Pentax Medical, Intromedic and National Cancer.

Topics: Adenocarcinoma; Animals; Aspirin; Barrett Esophagus; Carcinogenesis; Cell Line, Tumor; Cell Proliferation; Cyclooxygenase 1; Cyclooxygenase 2; Disease Models, Animal; Esophageal Neoplasms; Extracellular Signal-Regulated MAP Kinases; Female; Humans; Inflammation; Male; Mice, Inbred C57BL; Middle Aged; Molecular Targeted Therapy; Signal Transduction; STAT3 Transcription Factor; Thromboxane A2

The percentage of diabetic patients who do not benefit from the protective effect of aspirin is larger than in other populations at cardiovascular risk.. We compared the ability of aspirin to suppress TxA2 and platelet activation in vivo, in type-2 diabetics vs. high-risk non-diabetic patients.. Urinary 11-dehydro-TXB2, plasma sCD40 L, and sP-selectin were measured, together with indices of low-grade inflammation, glycemic control, and lipid profile, in 82 patients with type-2 diabetes and 39 without diabetes, treated with low doses of aspirin.. Urinary 11-dehydro-TxB2, plasma sCD40L and sP-selectin were significantly higher in diabetics than in controls: [38.9 (27.8-63.3) vs. 28.5 (22.5-43.9) ng mmol(-1) of creatinine, P = 0.02], [1.06 (0.42-3.06) vs. 0.35 (0.22-0.95) ng mL(-1); P = 0.0001], [37.0 (16.8-85.6) vs. 20.0 (11.2-35.6) ng mL(-1), P = 0.0001], respectively. The proportion of individuals with diabetes increased across quartiles of 11-dehydro-TxB2, sCD40L, and sP-selectin, with the highest quartiles of 11-dehydro-TxB2, sCD40L and sP-selectin, including 66%, 93.3%, and 93.3% of individuals with diabetes. Markers of platelet activation positively correlated with indices of glycemic control but not with markers of low-grade inflammation.. Platelet dysfunction associated with insufficient glycemic control, may mediate persistent platelet activation under aspirin treatment.

Topics: Aspirin; Biomarkers; Blood Glucose; Case-Control Studies; Diabetes Mellitus, Type 2; Glycemic Index; Humans; Inflammation; Platelet Activation; Thromboxane A2

We evaluated whether renin-angiotensin system (RAS) blockade attenuates cardiovascular events.. Because inflammation and enhanced thrombogenesis are hallmarks of atherosclerosis, we assessed whether RAS inhibition elicits anti-inflammatory and anti-aggregatory effects.. Interleukin 6 (IL-6), high-sensitivity C-reactive protein (hsCRP), metalloprotease 9 (MMP-9), and interleukin 10 (IL-10) were determined in patients with coronary artery disease (CAD) and arterial hypertension six to eight weeks after coronary angioplasty (low-density lipoprotein serum levels <150 mg/dl). Patients were randomized double-blind to either 20 mg enalapril (ENAL, n = 27) or 300 mg irbesartan (IRB, n = 21) for 3 months. Blood samples were drawn at baseline and at three months. Thromboxane A2-induced platelet aggregation was determined turbidimetrically; urine bicyclo-prostaglandin E2 (PGE(2)) and inflammatory markers were measured by enzyme-linked immunosorbent assay technique.. Both treatment regimens enhanced serum IL-10 levels (IRB p < 0.001, ENAL p < 0.03) and reduced serum MMP-9 protein (IRB p < 0.001, ENAL p < 0.05) and MMP-9 activity (IRB p < 0.005, ENAL p < 0.05). Only IRB reduced serum IL-6 and hsCRP levels significantly compared with baseline (p < 0.01), whereas ENAL did not (hsCRP p < 0.02 IRB vs. ENAL, p < 0.01 IRB vs. ENAL). Platelet aggregation was only reduced by IRB (p < 0.001, ENAL p < 0.06, IRB vs. ENAL p < 0.001) while urine PGE(2) levels remained unchanged.. Angiotensin-converting enzyme (ACE) inhibition and angiotensin II type 1 receptor (AT1) blockade reduced serum MMP-9 protein/activity to a similar extent, and only AT1 blockade reduced hsCRP, IL-6, and platelet aggregation in patients with CAD. Thus, AT1-blockade appears to exert stronger systemic anti-inflammatory and anti-aggregatory effects compared with ACE inhibition.

Topics: Angiotensin II Type 1 Receptor Blockers; Angiotensin-Converting Enzyme Inhibitors; Biomarkers; Biphenyl Compounds; C-Reactive Protein; Coronary Artery Disease; Dinoprostone; Double-Blind Method; Enalapril; Female; Humans; Hypertension; Inflammation; Interleukin-10; Interleukin-6; Irbesartan; Male; Matrix Metalloproteinase 9; Middle Aged; Platelet Aggregation; Tetrazoles; Thromboxane A2

To investigate early events possibly related to the development of diabetic angiopathy, we examined whether 8-iso-prostaglandin F2alpha (8-iso-PGF2alpha) formation, a marker of in vivo oxidant stress, is altered in different stages of type 1 diabetes (T1DM) and whether it correlates with the rate of thromboxane (TX) A2 biosynthesis, a marker of in vivo platelet activation. We also investigated the relationship between inflammatory markers and F2-isoprostane formation in this setting.. A cross-sectional study was performed in 23 insulin-treated patients aged <18 years with new-onset T1DM (1 year, group B). Urinary 8-iso-PGF2alpha and 11-dehydro-TXB2 were measured in all patients and in age- and gender-matched controls. Circulating interleukin-6 (IL-6), tumor necrosis factor-alpha, and C-reactive protein were also determined as markers of the inflammatory response. Fifteen of the 23 children in group A were reexamined after 12 months. Compared with either controls or group B, diabetic children in group A showed significantly higher levels of 8-iso-PGF2alpha, 11-dehydro-TXB2, IL-6, tumor necrosis factor-alpha, and C-reactive protein. Statistically significant correlations between IL-6 and both 8-iso-PGF2alpha (r=0.63, P<0.001) and 11-dehydro-TXB2 (r=0.51, P<0.01) were observed. The 15 patients reexamined after 1 year showed a significant reduction in lipid peroxidation and platelet activation (P<0.02 and P<0.001, respectively), consistent with reduced levels of IL-6 and tumor necrosis factor-alpha.. These results demonstrate that enhanced lipid peroxidation and platelet activation represent early events in T1DM that are possibly related to an acute inflammatory response. These noninvasive indexes may help in further examining T1DM pathophysiology and monitoring pharmacological interventions to interfere with disease development and progression.

Topics: Adolescent; Biomarkers; C-Reactive Protein; Child; Cross-Sectional Studies; Diabetes Mellitus, Type 1; Dinoprost; Disease Progression; F2-Isoprostanes; Female; Follow-Up Studies; Humans; Inflammation; Insulin; Interleukin-6; Lipid Peroxidation; Male; Oxidative Stress; Platelet Activation; Reference Values; Thromboxane A2; Thromboxane B2; Time; Tumor Necrosis Factor-alpha

Angiotensin II (Ang II) type 1 receptor (AT(1)) antagonists such as losartan (LOS) are widely used for the treatment of hypertension and elicit antiinflammatory and antiaggregatory in vitro and in patients, although the underlying mechanism are unclear. Following computer-based molecule similarity, we proposed that on cytochrome-P450 degradation, the LOS metabolite EXP3179 is generated, which shows molecule homology to indomethacin, a cyclooxygenase inhibitor with antiinflammatory and antiaggregatory properties. Subsequently, serum-levels of EXP3179 were determined for 8 hours in patients receiving a single oral dose of 100 mg LOS. High-performance liquid chromatography followed by liquid chromatography-mass spectrometry (GC-MS) [corrected] from serum samples revealed a maximum of 10(-7) mol/L for EXP3179 peaking between 3 to 4 hours. The increase in serum-EXP3179 levels was associated with a significant reduction in platelet aggregation in vivo (-35+/-4%, P<0.001 versus control). EXP3179 generation was investigated in a chemical reaction mimicking the liver cytochrome-P450-dependent LOS-degradation and human endothelial cells were exposed to Ang II or lipopolysaccharides (LPS) in the presence of EXP3179 (10(-7) mol/L). LPS- and Ang II-induced COX-2 transcription was abolished by EXP3179. Moreover, EXP3179 significantly reduced Ang II- and LPS-induced formation of prostaglandin F2alpha as determined by GC-MS [corrected]. Thus, antiinflammatory properties of LOS are mediated via its EXP3179 metabolite by abolishing COX-2 mRNA upregulation and COX-dependent TXA2 and PGF2alpha generation. Serum levels of EXP3179 are detectable in patients in concentrations that exhibit antiinflammatory and antiaggregatory properties in vitro.

Topics: Angiotensin II; Angiotensin Receptor Antagonists; Arachidonic Acid; Biotransformation; Cells, Cultured; Cyclooxygenase 2; Dinoprost; Drug Design; Endothelium, Vascular; Enzyme Activation; Female; Humans; Hypertension; Imidazoles; Inflammation; Intercellular Adhesion Molecule-1; Isoenzymes; Lipopolysaccharides; Losartan; Male; Membrane Proteins; Middle Aged; Platelet Aggregation; Prostaglandin-Endoperoxide Synthases; Receptor, Angiotensin, Type 1; Receptors, Angiotensin; RNA, Messenger; Tetrazoles; Thromboxane A2; Up-Regulation; Vasoconstrictor Agents

Aside from the established immune-mediated etiology of multiple sclerosis (MS), compelling evidence implicates platelets as important players in disease pathogenesis. Specifically, numerous studies have highlighted that activated platelets promote the central nervous system (CNS)-directed adaptive immune response early in the disease course. Platelets, therefore, present a novel opportunity for modulating the neuroinflammatory process that characterizes MS. We hypothesized that the well-known antiplatelet agent acetylsalicylic acid (ASA) could inhibit neuroinflammation by affecting platelets if applied at low-dose and investigated its effect during experimental autoimmune encephalomyelitis (EAE) as a model to study MS. We found that oral administration of low-dose ASA alleviates symptoms of EAE accompanied by reduced inflammatory infiltrates and less extensive demyelination. Remarkably, the percentage of CNS-infiltrated CD4

Topics: Animals; Aspirin; Blood Platelets; Brain; CD4-Positive T-Lymphocytes; Disease Models, Animal; Dose-Response Relationship, Drug; Encephalomyelitis, Autoimmune, Experimental; Inflammation; Mice, Inbred C57BL; Multiple Sclerosis; Platelet Aggregation Inhibitors; Thromboxane A2

[Figure: see text].

Topics: Animals; Cells, Cultured; Diaphragm; Disease Models, Animal; Humans; Inflammation; Lipopolysaccharides; Lymphangiogenesis; Lymphatic Vessels; Macrophages, Peritoneal; Male; Mice, Inbred C57BL; Mice, Knockout; Receptors, Thromboxane A2, Prostaglandin H2; Signal Transduction; T-Lymphocytes; Thromboxane A2; Vascular Endothelial Growth Factor C; Vascular Endothelial Growth Factor D

A convenient approach to modulation of the inflammation has an influence on the production of inflammatory mediators - icosanoids, generated in arachidonic acid (AA) metabolism. The common therapeutic activity of non-steroidal anti-inflammatory drugs (NSAID), such as aspirin, includes inhibition of two crucial enzymes of AA metabolism - cyclooxygenase- 1 and -2 (COX-1/2), with certain risk for gastrointestinal and renal intolerance. Ever since the enrolment of COX-2, particularly overabundance of its main products prostaglandin E2 (PGE2) and thromboxane A2 (TXA2) in numerous pathological processes was recognized, it became a significant therapeutic target.. The aim of this study was to examine the effects of synthesized organo-fluorine compounds on PGE2 and TXA2 production in the inflammation process.. Trifluoromethyl compounds were synthesized from N-benzyl trifluoromethyl aldimine, commercially available 2-methyl or 2-phenyl α-bromo esters (β-lactams trans-1 and trans-2 and trifluoromethyl β-amino ester, respectively) and methyl 2-isocyanoacetate (2-imidazoline trans-4). The reactions proceeded with high geometric selectivity, furnishing the desired products in good yields. The influence of newly synthesized compounds on PGE2 and TXA2 production in human leukemic U937 macrophages on both enzyme activity and gene expression levels was observed.. Among the tested trifluoromethyl compounds, methyl trans-1-benzyl-5-(trifluoromethyl)- 4,5-dihydro-1H-imidazole-4-carboxylate (trans-4) can be distinguished as the most powerful antiinflammatory agent, probably due to its trifluoromethyl-imidazoline moiety.. Some further structural modifications in tested compounds and particularly in the synthesis of different trifluoromethyl imidazolines could contribute to the development of new COX-2 inhibitors and potent anti-inflammatory agents.

Topics: Dinoprostone; Dose-Response Relationship, Drug; Humans; Hydrocarbons, Fluorinated; Inflammation; Macrophages; Molecular Structure; Structure-Activity Relationship; Thromboxane A2; Tumor Cells, Cultured; U937 Cells

Topics: Abelson murine leukemia virus; Cytokines; Dinoprostone; Humans; Imatinib Mesylate; Inflammation; Leukemia; Lipopolysaccharides; Monocytes; NF-kappa B; Philadelphia Chromosome; Platelet Activation; Proto-Oncogene Proteins c-bcr; Receptors, Prostaglandin E, EP4 Subtype; Signal Transduction; Th1-Th2 Balance; Thromboxane A2; U937 Cells

Merlot are worldwide recognized red wines. Several studies show that red wines have health benefits, mainly due to their phenolic constituents. This study evaluates twelve Serbian and other five European (French, Italian, Macedonian, Slovenian, Spanish) Merlot wines in respect of their phenolic composition and biological activity. The latter was evaluated through a set of in vitro experiments related to common benefits of moderate red wine consumption in the prevention of cardiovascular diseases. Among the examined phenolics, the most abundant acid in all samples was the gallic acid (14.3-58.3 mg/L), catechin (9.1-49.3 mg/L) was the dominant flavonoid, malvidin-3-O-glucoside (2.63-66.5 mg/L) leading anthocyanin, whereas resveratrol was found in a usual concentration (0.18-4.67 mg/L). Differences determined in phenolic profiles, mainly in content of quercetin, rutin and p-coumaric acid, leaded to separation of Serbian from foreing Merlot wines. Results of standard antioxidant assays (DPPH

Topics: Anti-Inflammatory Agents; Antioxidants; Cell Line, Tumor; Dinoprostone; Flavonoids; Humans; Inflammation; Macrophages; Oxidation-Reduction; Phenols; Thromboxane A2; Wine

Platelets are well known for their role in hemostasis but are also increasingly recognized for their supporting role in innate immune responses. Here, we studied the role of platelets in the development of peripheral inflammation and found that platelets colocalize with macrophages in the inflamed tissue outside of blood vessels in different animal models for cutaneous inflammation. Collagen-treatment of macrophages isolated from paws during zymosan-induced inflammation induced thromboxane synthesis through the platelet-expressed collagen receptor glycoprotein VI. Deletion of glycoprotein VI or its downstream effector thromboxane A2 receptor (TP) reduced zymosan-induced mechanical allodynia without altering macrophage recruitment or formation of macrophage/platelet complexes. Instead, macrophages in inflamed paws of glycoprotein VI- and TP-deficient mice exhibited an increased expression of anti-inflammatory markers and synthesized less proinflammatory mediators (prostaglandin E

Topics: Animals; Blood Platelets; Collagen; Female; Gene Deletion; Inflammation; Lectins, C-Type; Macrophages; Male; Mannose Receptor; Mannose-Binding Lectins; Mice; Mice, Inbred C57BL; Phenotype; Platelet Membrane Glycoproteins; Receptors, Cell Surface; Receptors, Thromboxane A2, Prostaglandin H2; Skin; Thromboxane A2

Psoriasis is a chronic relapsing immune mediated disorder of the skin. The disease presents itself with well featured clinical and histological characteristics however the aetiology of the disease still remains obscure. The current systemic therapies aim to eliminate the symptoms of disease rather than offering a complete cure. Parangichakkai chooranam (PC), a Siddha oral herbal formulation has been widely prescribed for the treatment of psoriasis. Though the medication is highly prescribed by the Siddha healers the mechanism of PC for the treatment of psoriasis remains to be elucidated. The current study utilizes an integrated systems pharmacology approach to decipher the mechanism of action of PC. The comprehensive network pharmacological approach resulted in the construction of a Compound-Target network which encloses 155 compounds and 583 protein targets. A Disease-Target network was constructed by assembling disease proteins and their partners. When the compound targets were mapped to the network their involvement as controllers of the disease and triggers of disease associated comorbidities were identified. A Target-Pathway network raised from the pathway enrichment analysis not only identified disease specific pathways but also the pathways mediating secondary complications such as skin hemostasis, wound healing, desquamation and itch. The present work sheds light on the mechanism of action of PC in treating psoriasis. This work not only highlights the pharmacological action of the formulation but also emphasis on safe herbal remedies offered by the Siddha medicinal system.

Topics: Biological Availability; Humans; Inflammation; Medicine, Ayurvedic; Pharmacology; Phytochemicals; Phytotherapy; Plant Extracts; Psoriasis; Signal Transduction; Systems Biology; Thromboxane A2

Cysteinyl leukotrienes (cysLTs) are bronchoconstricting lipid mediators that amplify eosinophilic airway inflammation by incompletely understood mechanisms. We recently found that LTC4, the parent cysLT, potently activates platelets in vitro and induces airway eosinophilia in allergen-sensitized and -challenged mice by a platelet- and type 2 cysLT receptor-dependent pathway. We now demonstrate that this pathway requires production of thromboxane A2 and signaling through both hematopoietic and lung tissue-associated T prostanoid (TP) receptors. Intranasal administration of LTC4 to OVA-sensitized C57BL/6 mice markedly increased the numbers of eosinophils in the bronchoalveolar lavage fluid, while simultaneously decreasing the percentages of eosinophils in the blood by a TP receptor-dependent mechanism. LTC4 upregulated the expressions of ICAM-1 and VCAM-1 in an aspirin-sensitive and TP receptor-dependent manner. Both hematopoietic and nonhematopoietic TP receptors were essential for LTC4 to induce eosinophil recruitment. Thus, the autocrine and paracrine functions of thromboxane A2 act downstream of LTC4/type 2 cysLT receptor signaling on platelets to markedly amplify eosinophil recruitment through pulmonary vascular adhesion pathways. The findings suggest applications for TP receptor antagonists in cases of asthma with high levels of cysLT production.

Topics: Allergens; Animals; Aspirin; Asthma; Blood Platelets; Bone Marrow Transplantation; Bronchoalveolar Lavage Fluid; Cysteine; Eosinophilia; Inflammation; Intercellular Adhesion Molecule-1; Leukotriene Antagonists; Leukotriene C4; Leukotrienes; Lung; Mice; Mice, Inbred C57BL; Mice, Knockout; Ovalbumin; Platelet Activation; Receptors, Prostaglandin; Thromboxane A2; Vascular Cell Adhesion Molecule-1

It is well known that exposure to fluorides lead to an increased ROS production and enhances the inflammatory reactions. Therefore we decided to examine whether cyclooxygenases (particular COX-2) activity and expression may be changed by fluoride in THP1 macrophages and in this way may change the prostanoids biosynthesis. In the present work we demonstrate that fluoride increased concentration of PGE2 and TXA2 in THP1 macrophages. Following exposure to 1-10 μM NaF, COX-2 protein and COX-2 transcript increased markedly. COX-2 protein up-regulation probably is mediated by ROS, produced during fluoride-induced inflammatory reactions. Additional fluoride activates the transcription factor, nuclear factor (NF)-kappaB, which is involved in the up-regulation of COX-2 gene expression. This study indicated that even in small concentrations fluoride changes the amounts and activity of COX-1 and COX-2 enzymes taking part in the initiating and development of inflammatory process.

Topics: Cell Differentiation; Cell Line; Cyclooxygenase 1; Cyclooxygenase 2; Dinoprostone; Humans; Inflammation; Macrophages; Monocytes; Sodium Fluoride; Thromboxane A2

Circulating microparticles play a pro-inflammatory and procoagulant detrimental role in the vascular dysfunction of septic shock. It was the objective of this study to investigate mechanisms by which a pharmacological modulation of microparticles could affect vascular dysfunction in a rat model of septic shock. Septic or sham rats were treated by activated protein C (aPC) and resuscitated during 4 hours. Their microparticles were harvested and inoculated to another set of healthy recipient rats. Haemodynamic parameters were monitored, circulating total procoagulant microparticles assessed by prothrombinase assay, and their cell origin characterised. Mesenteric resistance arteries, aorta and heart were harvested for western blotting analysis. We found that a) the amount and phenotype of circulating microparticles were altered in septic rats with an enhanced endothelial, leucocyte and platelet contribution; b) aPC treatment significantly reduced the generation of leucocyte microparticles and norepinephrine requirements to reach the mean arterial pressure target in septic rats; c) Microparticles from untreated septic rats, but not from aPC-treated ones, significantly reduced the healthy recipients' mean arterial pressure; d) Microparticle thromboxane content and aPC activity were significantly increased in aPC-treated septic rats. In inoculated naïve recipients, microparticles from aPC-treated septic rats prompted reduced NF-κB and cyclooxygenase-2 arterial activation, blunted the generation of pro-inflammatory iNOS and secondarily increased platelet and endothelial microparticles. In conclusion, in this septic shock model, increased circulating levels of procoagulant microparticles led to negative haemodynamic outcomes. Pharmacological treatment by aPC modified the cell origin and levels of circulating microparticles, thereby limiting vascular inflammation and favouring haemodynamic improvement.

Topics: Animals; Cell-Derived Microparticles; Coagulants; Cyclooxygenase 2; Hemodynamics; Humans; Inflammation; Male; NF-kappa B; Phenotype; Protein C; Rats; Rats, Wistar; Recombinant Proteins; Shock, Septic; Thromboplastin; Thromboxane A2; Time Factors; Treatment Outcome

Toona sinensis Roem. (Meliaceae; Toona sinensis; Chinese toon) is a type of arbor that is widely distributed in Asia. The fruits of Toona sinensis Roem has been traditionally recognized for treatment of cerebrovascular diseases. To evaluate the potential clinical use of the fruits of Toona sinensis Roem, we determined the dose dependence of the neuroprotective efficacy in a focal cerebral ischemic reperfusion model of rats and explored the underlying mechanisms.. Rats were subjected to occlusion of the middle cerebral artery (MCAO) by a nylon filament and treated with different doses (20mg/kg and 30 mg/kg) of n-butanol soluble fraction of the water extract of Chinese toon fruit or the vehicle for 1 week before induction of ischemia, s.i.d... n-Butanol soluble fraction of the water extract of Chinese toon fruit reduced in a dose-dependent manner the ischemia-induced cerebral infarct and edema volume and attenuated neurological deficits observed at 6h point after ischemia. n-Butanol soluble fraction of the water extract of Chinese toon fruit reduced the levels of nitrate, nitrite, lipid peroxidation, cyclooxygenase-1, thromboxane in post-ischemic brain. n-Butanol soluble fraction of the water extract of Chinese toon fruit adjusted the elevation of the activity of glutathione peroxidase and superoxide dismutase in ischemic brain.. The present study was the first evidence of effectiveness of n-butanol soluble fraction of the water extract of Chinese toon fruit in the rat stroke models, as it reduced infarct volume, inhibited the oxidative stress and inflammation.

Topics: 1-Butanol; Animals; Brain Ischemia; Epoprostenol; Fruit; Gene Expression Regulation; Glutathione Peroxidase; Inflammation; Male; Malondialdehyde; Meliaceae; Oxidative Stress; Plant Extracts; Prostaglandin-Endoperoxide Synthases; Rats; Rats, Sprague-Dawley; Superoxide Dismutase; Thromboxane A2; Water

In humans, LL-37 and eicosanoids are important mediators of inflammation and immune responses. Here we report that LL-37 promotes leukotriene B4 (LTB4) and thromboxane A2 (TXA2) generation by human monocyte-derived macrophages (HMDMs). LL-37 evokes calcium mobilization apparently via the P2X7 receptor (P2X7R), activation of ERK1/2 and p38 MAPKs, as well as cytosolic phospholipase A2 (cPLA2) and 5-lipoxygenase in HMDMs, leading to an early (1 h) release of LTB4. Similarly, TXA2 production at an early time involved the same signaling sequence along an LL-37-P2X7R-cPLA2-cyclooxygenase-1 (COX-1) axis. However, at later (6-8 h) time points, internalized LL-37 up-regulates COX-2 expression, promoting TXA2 production. Furthermore, intraperitoneal injection of mice with murine cathelicidin-related antimicrobial peptide (mCRAMP) induces significantly higher levels of LTB4 and TXA2 in mouse ascites rich in macrophages. Conversely, cathelicidin-deficient (Cnlp(-/-)) mice produce much less LTB4 and TXB2 in vivo in response to TNF-α compared with control mice. We conclude that LL-37 elicits a biphasic release of eicosanoids in macrophages with early, Ca(2+)-dependent formation of LTB4 and TXA2 followed by a late peak of TXA2, generated via induction of COX-2 by internalized LL-37, thus allowing eicosanoid production in a temporally controlled manner. Moreover, our findings provide evidence that LL-37 is an endogenous regulator of eicosanoid-dependent inflammatory responses in vivo.

Topics: Amino Acid Sequence; Animals; Antimicrobial Cationic Peptides; Arachidonate 5-Lipoxygenase; Calcium Signaling; Cathelicidins; Cells, Cultured; Eicosanoids; Humans; Inflammation; Leukotriene B4; Macrophages; Male; MAP Kinase Signaling System; Mice; Mice, Inbred C57BL; Molecular Sequence Data; Peritonitis; Phospholipases A2, Cytosolic; Phosphorylation; Prostaglandin-Endoperoxide Synthases; Protein Kinase Inhibitors; Protein Processing, Post-Translational; Receptors, Purinergic P2X7; Recombinant Proteins; Thromboxane A2; Tumor Necrosis Factor-alpha

Low-density lipoproteins (LDL), occurring in vivo in both their native and oxidative form, modulate platelet function and thereby contribute to atherothrombosis. We recently identified and demonstrated that 'ApoB100 danger-associated signal 1' (ApoBDS-1), a native peptide derived from Apolipoprotein B-100 (ApoB100) of LDL, induces inflammatory responses in innate immune cells. Platelets are critically involved in the development as well as in the lethal consequences of atherothrombotic diseases, but whether ApoBDS-1 has also an impact on platelet function is unknown. In this study we examined the effect of ApoBDS-1 on human platelet function and platelet-leukocyte interactions in vitro. Stimulation with ApoBDS-1 induced platelet activation, degranulation, adhesion and release of proinflammatory cytokines. ApoBDS-1-stimulated platelets triggered innate immune responses by augmenting leukocyte activation, adhesion and transmigration to/through activated HUVEC monolayers, under flow conditions. These platelet-activating effects were sequence-specific, and stimulation of platelets with ApoBDS-1 activated intracellular signalling pathways, including Ca2+, PI3K/Akt, PLC, and p38- and ERK-MAPK. Moreover, our data indicates that ApoBDS-1-induced platelet activation is partially dependent of positive feedback from ADP on P2Y1 and P2Y12, and TxA2. In conclusion, we demonstrate that ApoBDS-1 is an effective platelet agonist, boosting platelet-leukocyte's proinflammatory responses, and potentially contributing to the multifaceted inflammatory-promoting effects of LDL in the pathogenesis of atherothrombosis.

Topics: Adenosine Diphosphate; Adult; Apolipoprotein B-100; Blood Platelets; Cell Communication; Cells, Cultured; Coculture Techniques; Cytokines; Human Umbilical Vein Endothelial Cells; Humans; Immunity, Innate; Inflammation; Inflammation Mediators; Leukocytes; Platelet Activation; Platelet Adhesiveness; Receptors, Purinergic P2Y12; Signal Transduction; Thromboxane A2; Time Factors; Young Adult

Angiogenically stimulated alternative monocytes (aMO2) could be established as cellular release system accelerating the endothelialization of polymers rendering their surfaces hemocompatibility in a short-term study. However, for their clinical application it is essential that aMO2 do not switch back to the MO1 state sustaining their capability as cellular release system over an extended period of time. We explored whether aMO2 can maintain their differentiation state over 21 days in a mono- and in a co-culture with HUVEC. In comparison, the influence of recombinant VEGF-A165 on the endothelialization of biomaterials was assessed including endothelial cell (HUVEC) density, organisation of the endothelial cytoskeleton, cytokine secretion profile and release of prostacyclin, thromboxane A2 and matrix metalloproteinases. In mono-culture aMO2 secreted high amounts of VEGF and other growth factors/cytokines. Co-cultured with HUVEC, aMO2 accelerated the formation of a confluent HUVEC monolayer. Furthermore, no pro-inflammatory cytokines were found, neither in aMO2-mono, nor in co-cultures with HUVEC indicating that the majority of the aMO2 remained stable in their aMO2 state during the 21 days of cultivation. In contrast, the addition of recombinant VEGF-A165 instead of the co-culture with aMO2 resulted in the formation of stress fibres, dissociated marginal filament bands, and a detachment of HUVEC. In addition, the profile of bioactive agents of HUVEC (e.g. prostacyclin, thromboxane A2, matrix metalloproteinases, IFN-γ and TNF-α) was influenced by the VEGF-A165 treatment inducing the detachment of HUVEC. In conclusion, in co-culture with HUVEC aMO2 remained stable in their type 2 state over 21 days confirming the suitability of aMO2 as biological release system for the endothelialization of biomaterial surfaces with constant release of angiogenic factors but without secretion of pro-inflammatory cytokines over three weeks. Therefore, this endothelialization approach seems to be appropriate to improve the hemocompatibility of cardiovascular implant materials in vitro, and proved to be superior to the use of recombinant VEGF-A165.

Topics: Angiogenesis Inducing Agents; Biocompatible Materials; Cells, Cultured; Coculture Techniques; Cytokines; Epoprostenol; Human Umbilical Vein Endothelial Cells; Humans; Inflammation; Monocytes; Neovascularization, Pathologic; Neovascularization, Physiologic; Phenotype; Recombinant Proteins; Thromboxane A2; Vascular Endothelial Growth Factor A

Interactions between dendritic cells (DCs) and T cells control the decision between activation and tolerance induction. Thromboxane A2 (TXA2) and its receptor TP have been suggested to regulate adaptive immune responses through control of T cell-DC interactions. Here, we show that this control is achieved by selectively reducing expansion of low-avidity CD4(+) T cells. During inflammation, weak tetramer-binding TP-deficient CD4(+) T cells were preferentially expanded compared with TP-proficient CD4(+) T cells. Using intravital imaging of cellular interactions in reactive peripheral lymph nodes (PLNs), we found that TXA2 led to disruption of low- but not high-avidity interactions between DCs and CD4(+) T cells. Lack of TP correlated with higher expression of activation markers on stimulated CD4(+) T cells and with augmented accumulation of follicular helper T cells (TFH), which correlated with increased low-avidity IgG responses. In sum, our data suggest that tonic suppression of weak CD4(+) T cell-DC interactions by TXA2-TP signaling improves the overall quality of adaptive immune responses.

Topics: Animals; Antibody Affinity; Biomarkers; CD4-Positive T-Lymphocytes; Cell Communication; Chickens; Dendritic Cells; Histocompatibility Antigens; Immunoglobulin G; Immunologic Factors; Inflammation; Lymphocyte Activation; Lymphocyte Count; Male; Mice, Inbred C57BL; Mice, Transgenic; Microscopy, Fluorescence, Multiphoton; Ovalbumin; Receptors, Thromboxane A2, Prostaglandin H2; Signal Transduction; T-Lymphocytes, Helper-Inducer; Thromboxane A2

Cardiovascular dysfunction is a primary independent predictor of age-related morbidity and mortality. Frailty is associated with activation of inflammatory pathways and fatigue that commonly presents and progresses with age. Interleukin 10 (IL-10), the cytokine synthesis inhibitory factor, is an anti-inflammatory cytokine produced by immune and non-immune cells. Homozygous deletion of IL-10 in mice yields a phenotype that is consistent with human frailty, including age-related increases in serum inflammatory mediators, muscular weakness, higher levels of IGF-1 at midlife, and early mortality. While emerging evidence suggests a role for IL-10 in vascular protection, a clear mechanism has not yet been elucidated.. In order to evaluate the role of IL-10 in maintenance of vascular function, force tension myography was utilized to access ex-vivo endothelium dependent vasorelaxation in vessels isolated from IL-10 knockout IL-10(tm/tm) and control mice. Pulse wave velocity ((PWV), index of stiffness) of vasculature was measured using ultrasound and blood pressure was measured using the tail cuff method. Echocardiography was used to elucidated structure and functional changes in the heart.. Mean arterial pressures were significantly higher in IL-10(tm/tm) mice as compared to C57BL6/wild type (WT) controls. PWV was increased in IL-10(tm/tm) indicating stiffer vasculature. Endothelial intact aortic rings isolated from IL-10(tm/tm) mice demonstrated impaired vasodilation at low acetylcholine doses and vasoconstriction at higher doses whereas vasorelaxation responses were preserved in rings from WT mice. Cyclo-oxygenase (COX-2)/thromboxane A2 inhibitors improved endothelial dependent vasorelaxation and reversed vasoconstriction. Left ventricular end systolic diameter, left ventricular mass, isovolumic relaxation time, fractional shortening and ejection fraction were all significantly different in the aged IL-10(tm/tm) mice compared to WT mice.. Aged IL-10(tm/tm) mice have stiffer vessels and decreased vascular relaxation due to an increase in eicosanoids, specifically COX-2 activity and resultant thromboxane A2 receptor activation. Our results also suggest that aging IL-10(tm/tm) mice have an increased heart size and impaired cardiac function compared to age-matched WT mice. While further studies will be necessary to determine if this age-related phenotype develops as a result of inflammatory pathway activation or lack of IL-10, it is essential for maintaining the vascular compliance and endothelial function during the aging process. Given that a similar cardiovascular phenotype is present in frail, older adults, these findings further support the utility of the IL-10(tm/tm) mouse as a model of frailty.

Topics: Age Factors; Aging; Animals; Aorta; Arterial Pressure; Cardiovascular Diseases; Cyclooxygenase 2; Cyclooxygenase 2 Inhibitors; Dose-Response Relationship, Drug; Echocardiography, Doppler; Endothelium, Vascular; Genotype; Inflammation; Inflammation Mediators; Interleukin-10; Mice; Mice, Inbred C57BL; Mice, Knockout; Myography; Phenotype; Pulse Wave Analysis; Stroke Volume; Thromboxane A2; Vascular Stiffness; Vasoconstriction; Vasoconstrictor Agents; Vasodilation; Vasodilator Agents; Ventricular Function, Left

Tumor-associated inflammation is a driving force in several adult cancers and intake of low-dose aspirin has proven to reduce cancer incidence. Little is known about tumor-associated inflammation in pediatric neoplasms and no in vivo data exists on the effectiveness of low-dose aspirin on established tumors. The present study employs the transgenic TH-MYCN mouse model for neuroblastoma (NB) to evaluate inflammatory patterns paralleling tumor growth in vivo and low-dose aspirin as a therapeutic option for high-risk NB. Spontaneously arising abdominal tumors were monitored for tumor-associated inflammation ex vivo at various stages of disease and homozygous mice received daily low-dose aspirin (10mg/kg) using oral gavage or no treatment, from 4.5 to 6 weeks of age. Using flow cytometry, a transition from an adaptive immune response predominated by CD8(+) T cell in early neoplastic lesions, towards enrichment in immature cells of the innate immune system, including myeloid-derived suppressor cells, dendritic cells and tumor-associated macrophages, was detected during tumor progression. An M1 to M2 transition of tumor-associated macrophages was demonstrated, paralleled by a deterioration of dendritic cell status. Treatment with low-dose aspirin to mice homozygous for the TH-MYCN transgene significantly reduced the tumor burden (P < 0.01), the presence of tumor-associated cells of the innate immune system (P < 0.01), as well as the intratumoral expression of transforming growth factor-β, thromboxane A2 (P < 0.05) and prostaglandin D2 (P < 0.01). In conclusion, tumor-associated inflammation appears as a potential therapeutic target in NB and low-dose aspirin reduces tumor burden in the TH-MYCN transgenic mouse model of NB, hence warranting further studies on aspirin in high-risk NB.

Topics: Animals; Aspirin; CD4-Positive T-Lymphocytes; CD8-Positive T-Lymphocytes; Cytokines; Dendritic Cells; Disease Models, Animal; Disease Progression; Homozygote; Immunity, Innate; Inflammation; Macrophages; Mice; Mice, Transgenic; Neuroblastoma; Prostaglandin D2; Th2 Cells; Thromboxane A2; Transforming Growth Factor beta

Bradykinin, a vasoactive peptide, increases during inflammation and induces the formation of prostaglandins through specific receptor activation. Two types of receptors mediate the biological effects of bradykinin, B(1) and B(2) receptors. Although B(2) receptors are present in most tissues, B(1) receptors are expressed after inflammatory stimuli or tissue injury. Bradykinin has a high affinity for B(2) and a low affinity for B(1) receptors, whereas the opposite occurs for des-Arg(9)-bradykinin. Recently, it has been reported that nonsteroidal anti-inflammatory drugs have different inhibitory activities on cyclooxygenase isozymes, COX-1, COX-2, and COX-3. In the present study, we have investigated the contributions of different COX isozyme inhibitions and inflammation on bradykinin-induced effects of isolated rat aorta and urinary bladder smooth muscle contractions. Male Sprague-Dawley rats weighing 200-250 g were used in the study. The vasodilatory responses to bradykinin (1 nM-1 μM) were studied on isolated rat aorta rings contracted with norepinephrine (0.1 μM) following incubation with dipyrone (100, 700, and 2,000 μM). The relaxant responses of dipyrone (100, 700, and 2,000 μM) were also compared on the isolated rat urinary bladder contracted with bradykinin (n = 8). A bacterial lipopolysaccharide was used for the induction of inflammation (n = 8). The levels of PGE(2), PGF(1α), TXB(2), nitric oxide synthase (NOS), IL-10, and TNF-α were all determined in both the plasma and the perfusate of the aorta preparations (n = 5). The vasodilatory activities of bradykinin and des-Arg9-bradykinin were significantly increased upon the inhibition of COX-3 (dipyrone at 100 μM). These effects disappeared in the inflamed group. PGE(2), PGF1α, and TXB(2) were significantly high, but NOS activity was low in the aorta perfusate after the inhibition of COX-3. Dipyrone showed the relaxant activity of the urinary bladder contracted with bradykinin. The vasodilatory activity of des-Arg(9)-bradykinin was in the inflamed group but not in the non-inflamed group. Bradykinin did not contract urinary bladder in inflamed group. The results suggest that COX-induced products may play an important role in the bradykinin-induced rat aortic smooth muscle relaxations.

Topics: Animals; Aorta, Thoracic; Bradykinin; Cyclooxygenase 1; Cyclooxygenase 2; Cyclooxygenase Inhibitors; Dinoprostone; Dipyrone; In Vitro Techniques; Inflammation; Interleukin-10; Lipopolysaccharides; Male; Muscle Contraction; Muscle, Smooth; Muscle, Smooth, Vascular; Nitric Oxide Synthase; Norepinephrine; Prostaglandin-Endoperoxide Synthases; Prostaglandins; Prostaglandins F; Rats; Rats, Sprague-Dawley; Thromboxane A2; Tumor Necrosis Factor-alpha; Urinary Bladder

To evaluate whether impaired endothelial function and endothelial inflammatory response occur in parallel in the women with preeclampsia.. Venous blood was drawn from normal (n=40) and severe preeclamptic (sPE) (n=40) pregnant women when they were admitted to the L&D Unit and 24 hrs after delivery. Plasma and serum samples were extracted and measured for 6-keto PGF1α and TXB(2) (stable metabolites of PGI2 and TXA2), and intercellular adhesion molecule (ICAM) and vascular cell adhesion molecule (VCAM) by ELISA. Data are analyzed by Mann-Whitney test and paired t-test. The statistical significance is set as P<0.05. Results  Plasma 6-keto PGF1α levels were significantly reduced at admission and 24hr after delivery in sPE compared to normal pregnant controls, P<0.01. The ratio of 6-keto PGF1α and TXB(2) was significant less in sPE than that in normal pregnant controls before delivery. There was no significant difference for ICAM and VCAM levels between normal and patients with sPE before and after delivery.. Maternal 6-keto PGF1α levels and the ratio of 6-keto PGF1α and TXB(2) were decreased in patients with sPE compared to normal pregnant controls. In contrast, maternal ICAM and VCAM levels were not different between the two groups. These data suggest that serum ICAM and VCAM levels may not be sensitive inflammatory biomarkers for preeclampsia.

Topics: Adolescent; Adult; Biomarkers; Endothelium; Epoprostenol; Female; Gene Expression Regulation; Humans; Inflammation; Intercellular Adhesion Molecule-1; Pre-Eclampsia; Pregnancy; Thromboxane A2; Vascular Cell Adhesion Molecule-1

Paroxysmal atrial fibrillation might be a risk factor for stroke such as chronic atrial fibrillation. We examined the relation between mean platelet volume and paroxysmal atrial fibrillation to determine the effect of paroxysmal atrial fibrillation on the thrombotic state via elevated mean platelet volume. Mean platelet volume is a marker of platelet size, function, and activation. Increased mean platelet volume reflects active and large platelets that release more thromboxane A2 than smaller ones. We hypothesized that mean platelet volume is elevated in patients with paroxysmal atrial fibrillation. The study population comprised 103 consecutive patients who were detected to have paroxysmal atrial fibrillation by 24-h Holter monitoring and 87 control individuals with normal Holter monitoring. Mean platelet volume and inflammatory parameters were measured. Comprehensive clinical and echocardiographic data were collected. Patients with aortic and mitral stenosis, hyperthyroidism, hypothyroidism, malignancy, infection, and pregnancy were excluded from the study. Mean age of the patients was 63 +/- 11 vs. 45 +/- 14 years (P < 0.001) in paroxysmal atrial fibrillation and control groups, respectively. Fifty-seven patients (55%) in paroxysmal atrial fibrillation and 19 (21%) (P < 0.001) patients in control group were men. Mean platelet volume was significantly higher in the paroxysmal atrial fibrillation group when compared with control group (10.0 +/- 2.0 vs. 8.3 +/- 1.5 fl, respectively; P < 0.001). C-reactive protein (18.5 +/- 28 vs. 3.8 +/- 2 mg/l, respectively; P = 0.004) and erythrocyte sedimentation rate (21 +/- 21 vs. 12 +/- 7 mm/h, respectively; P = 0.01) were also higher in the paroxysmal atrial fibrillation group. There was no difference in white blood cell and platelet counts between groups. In a multivariate analysis, elevated mean platelet volume was associated with the occurrence of paroxysmal atrial fibrillation before and after adjustment for age and sex. Our results indicate that inflammatory markers such as C-reactive protein and erythrocyte sedimentation rate and the marker of platelet size and activity mean platelet volume are elevated in patients with paroxysmal atrial fibrillation.

Topics: Adult; Atrial Fibrillation; Biomarkers; Blood Platelets; Blood Sedimentation; C-Reactive Protein; Cell Size; Female; Humans; Inflammation; Inflammation Mediators; Male; Middle Aged; Platelet Activation; Thromboxane A2

Previous studies in mouse models showed that 12/15lipoxygenase (12/15LO) gene disruption diminishes atherosclerosis. Pharmacologic suppression of thromboxane (Tx) A(2) biosynthesis or blockade of its receptor also reduces the development of the disease in the same models. We tested the hypothesis that simultaneous genetic absence of 12/15LO with TxA(2) receptor blockade might result in an additive anti-atherogenic effect. Apolipoprotein E (apoE)-deficient mice and apoE-deficient mice lacking 12/15LO were maintained on normal chow diet, or chow supplemented with BM-573, a selective TxA(2) receptor antagonist, for 12 weeks. Urinary TxA(2) and prostacyclin metabolites, isoprostaneF(2*)-III and atherosclerotic aortic lesions were assessed. 12/15LO gene disruption resulted in significantly reduced atherosclerotic lesion areas and decreased urinary isoprostaneF(2*)-III in apoE-deficient mice. TxA(2) receptor antagonism alone also afforded a significant reduction in atherosclerosis in apoE-deficient mice. However, thromboxane receptor blockade resulted in an additive and more potent anti-inflammatory and anti-atherogenic effect when administered to apoE-deficient mice lacking 12/15LO. These results suggest that the 12/15LO- and TxA(2) receptor-mediated pro-atherogenic effects are two distinct pathways and represent two separate therapeutic targets for a better anti-atherogenic strategy.

Topics: Animals; Antioxidants; Apolipoproteins E; Arachidonate 12-Lipoxygenase; Arachidonate 15-Lipoxygenase; Atherosclerosis; Gene Expression Regulation; Inflammation; Mice; Mice, Inbred C57BL; Mice, Knockout; Receptors, Thromboxane; Thrombosis; Thromboxane A2; Vitamin E

Licofelone is an analogue of arachidonic acid that inhibits 5-lipoxygenase (LOX), cyclooxygenase (COX)-1 and COX-2. We investigated the effects of licofelone on cardiovascular derangements and production of thromboxane (Tx)A(2) induced by the inflammatory agonist n-formyl-methionyl-leucyl-phenylalanine (fMLP) in the rabbit, in comparison with those of aspirin or rofecoxib, inhibitors of COX-1 and COX-2, respectively. In control rabbits, injection of fMLP (30 nmol/kg) in the jugular vein evokes ischemic electrocardiographic (ECG) changes in the first 1-5 min, i.e. a profound depression of the ST segment and inversion of the T wave. Simultaneously, fMLP induces bradycardia and hypotension and increases TxB(2) blood levels. All changes are transient. Licofelone (60 mg/kg/5 days, p.os) prevented fMLP-induced ECG ischemic changes in all treated animals, reverted bradycardia and hypotension, and significantly reduced TxB(2). Aspirin (10 mg/kg/5 days, p.os) prevented ischemic ECG alterations in 2 out of 5 treated animals and did not modify either bradycardia or hypotension. One rabbit died two min after fMLP. In 2 rabbits, aspirin reduced TxB(2) levels by more than 80% respect to mean control values; the remaining two rabbits produced an amount of TxB(2) similar to controls. These two rabbits also showed ischemic ECG changes. Rofecoxib (10 mg/kg/5 days, p.os) did not prevent fMLP-induced ischemic ECG alteration, bradycardia and hypotension, and did not significantly modify the increase of TxB(2). These results indicate that the capacity of licofelone to efficiently suppress TxA(2) production, is responsible for the protection from the cardiovascular derangement triggered by an inflammatory stimulus.

Topics: Acetates; Animals; Aspirin; Blood Pressure; Cyclooxygenase Inhibitors; Disease Models, Animal; Electrocardiography; Heart Rate; Inflammation; Lactones; Leukotriene B4; Lipoxygenase Inhibitors; Male; Myocardial Ischemia; N-Formylmethionine Leucyl-Phenylalanine; Pyrroles; Rabbits; Sulfones; Thromboxane A2; Time Factors

Topics: Biological Evolution; Diet; Edible Grain; Fatty Acids, Unsaturated; Humans; Inflammation; Longevity; Myocardial Infarction; Nutritional Physiological Phenomena; Resorcinols; Thromboxane A2

Cystic fibrosis (CF) is caused by a mutation of the gene encoding the cystic fibrosis transmembrane conductance regulator (CFTR). We examined platelet function in CF patients because lung inflammation is part of this disease and platelets contribute to inflammation. CF patients had increased circulating leukocyte-platelet aggregates and increased platelet responsiveness to agonists compared with healthy controls. CF plasma caused activation of normal and CF platelets; however, activation was greater in CF platelets. Furthermore, washed CF platelets also showed increased reactivity to agonists. CF platelet hyperreactivity was incompletely inhibited by prostaglandin E(1) (PGE(1)). As demonstrated by Western blotting and reverse-transcriptase-polymerase chain reaction (RT-PCR), there was neither CFTR nor CFTR-specific mRNA in normal platelets. There were abnormalities in the fatty acid composition of membrane fractions of CF platelets. In summary, CF patients have an increase in circulating activated platelets and platelet reactivity, as determined by monocyte-platelet aggregation, neutrophil-platelet aggregation, and platelet surface P-selectin. This increased platelet activation in CF is the result of both a plasma factor(s) and an intrinsic platelet mechanism via cyclic adenosine monophosphate (cAMP)/adenylate cyclase, but not via platelet CFTR. Our findings may account, at least in part, for the beneficial effects of ibuprofen in CF.

Topics: Adenylyl Cyclases; Adolescent; Adult; Alprostadil; Anti-Inflammatory Agents, Non-Steroidal; Arachidonic Acid; Blood Platelets; Blotting, Western; Case-Control Studies; Cell Membrane; Child; Cyclic AMP; Cystic Fibrosis; Cystic Fibrosis Transmembrane Conductance Regulator; Fatty Acids; Genotype; Humans; Ibuprofen; Inflammation; Leukocytes; Monocytes; Neutrophils; P-Selectin; Platelet Activation; Reverse Transcriptase Polymerase Chain Reaction; RNA, Messenger; Thromboxane A2; Time Factors; Vitamin E

Plasma and urinary levels of malondialdehyde-like products (MDA) and isoprostanes were identified as markers of in vivo lipid peroxidation in an animal model of CCl4 poisoning. We sought to determine the extent to which the formation of these oxidation products is influenced by inhibition of the cyclooxygenase enzymes which catalytically generate proinflammatory lipid peroxidation products known as prostaglandins and thromboxane. In the present studies, after induction of oxidant stress in rats with CCl4, lipid peroxidation products measured in plasma and urine demonstrate that isoprostanes and MDA can be partially inhibited by cyclooxygenase inhibitors, albeit to different extents. The lowering of isoprostane and MDA formation, however, may not to due primarily to the diminution of catalytic generation of isoprostanes or MDA by the cyclooxygenases but, rather, may be the result of the suppression of nonenzymatic lipid peroxidation. This is suggested since 8,12-iso-iPF2alpha-VI is also reduced by indomethacin, yet, unlike other isoprostanes and MDA, it is not generated catalytically by the cyclooxygenase. Thus, although the two cyclooxygenase inhibitors we tested have statistically significant effects on the measurements of both isoprostanes and MDA in this study, the results provide evidence that these lipid-degradation products primarily constitute markers of oxidative stress.

Topics: Animals; Anti-Inflammatory Agents, Non-Steroidal; Biomarkers; Carbon Tetrachloride; Carbon Tetrachloride Poisoning; Chromatography, High Pressure Liquid; Free Radicals; Gas Chromatography-Mass Spectrometry; Immunoassay; Indomethacin; Inflammation; Lipid Metabolism; Lipid Peroxidation; Mass Spectrometry; Meclofenamic Acid; Oxidative Stress; Oxygen; Prostaglandins; Protein Isoforms; Rats; Rats, Inbred F344; Thromboxane A2; Time Factors

Systemic inflammation induces various adaptive responses including tachycardia. Although inflammation-associated tachycardia has been thought to result from increased sympathetic discharge caused by inflammatory signals of the immune system, definitive proof has been lacking. Prostanoids, including prostaglandin (PG) D(2), PGE(2), PGF(2alpha), PGI(2) and thromboxane (TX) A(2), exert their actions through specific receptors: DP, EP (EP(1), EP(2), EP(3), EP(4)), FP, IP and TP, respectively. Here we have examined the roles of prostanoids in inflammatory tachycardia using mice that lack each of these receptors individually. The TXA(2) analog I-BOP and PGF(2alpha) each increased the beating rate of the isolated atrium of wild-type mice in vitro through interaction with TP and FP receptors, respectively. The cytokine-induced increase in beating rate was markedly inhibited in atria from mice lacking either TP or FP receptors. The tachycardia induced in wild-type mice by injection of lipopolysaccharide (LPS) was greatly attenuated in TP-deficient or FP-deficient mice and was completely absent in mice lacking both TP and FP. The beta-blocker propranolol did not block the LPS-induced increase in heart rate in wild-type animals. Our results show that inflammatory tachycardia is caused by a direct action on the heart of TXA(2) and PGF(2alpha) formed under systemic inflammatory conditions.

Topics: Animals; Blood Pressure; Dinoprost; Electrocardiography; Heart Atria; Heart Rate; Inflammation; Lipopolysaccharides; Mice; Mice, Inbred C57BL; Mice, Knockout; Propranolol; Receptors, Prostaglandin; Receptors, Thromboxane A2, Prostaglandin H2; Tachycardia; Thromboxane A2

Bone morphogenetic protein receptor-2 (BMPR2)-heterozygous, mutant (BMPR2(+/-)) mice have a genetic trait similar to that of certain patients with idiopathic pulmonary arterial hypertension (IPAH). To understand the role of BMPR2 in the development of IPAH, we examined the phenotype of BMPR2(+/-) mice and their response to inflammatory stress.. BMPR2(+/-) mice were found to have the same life span, right ventricular systolic pressure (RVSP), and lung histology as those of wild-type mice under unstressed conditions. However, when treated with recombinant adenovirus expressing 5-lipoxygenase (Ad5LO), BMPR2(+/-) mice exhibited significantly higher RVSP than wild-type mice. The increase of RVSP occurred in the first 2 weeks after Ad5LO delivery. Modest but significant muscularization of distal pulmonary arterioles appeared in BMPR2(+/-) mice 4 weeks after Ad5LO treatment. Measurement of urinary metabolites of vasoactive molecules showed that cysteinyl leukotrienes, prostacyclin metabolites, and PGE2 were all increased to a similar degree in both BMPR2(+/-) and wild-type mice during 5LO transgene expression, whereas urinary endothelin-1 remained undetectable. Urinary thromboxane A2 metabolites, in contrast, were significantly higher in BMPR2(+/-) than in wild-type mice and paralleled the increase in RVSP. Platelet activation markers, serotonin, and soluble P-selectin showed a trend toward higher concentrations in BMPR2(+/-) than wild-type mice. Cell culture studies found that BMP treatment reduced interleukin-1beta-stimulated thromboxane A2 production in the pulmonary epithelial cell line A549.. BMPR2(+/-) mice do not develop pulmonary hypertension spontaneously; however, under inflammatory stress, they are more susceptible to an increase in RVSP, thromboxane A2 production, and vascular remodeling than wild-type mice.

Topics: Adenoviridae; Animals; Arachidonate 5-Lipoxygenase; Bone Morphogenetic Protein Receptors, Type II; Dinoprostone; Gene Transfer, Horizontal; Heterozygote; Hypertension, Pulmonary; Inflammation; Interleukin-1; Lung; Mice; Mice, Inbred C57BL; Mutation; Platelet Activation; Systole; Thromboxane A2

Intact myenteric ganglia from 4- to 10-day-old rats were isolated from the small intestine. The preparations were cultured overnight, and drugs were applied within this time frame (20 h). Whole cell patch-clamp technique was used to measure basal membrane potential and carbachol-induced depolarization at neurons within these ganglia. Pretreatment with TNF-alpha (100 ng/ml) hyperpolarized the membrane (from -31.0 +/- 2.7 mV under control conditions to -61.2 +/- 3.2 mV in the presence of the cytokine) and potentiated the depolarization induced by carbachol (from 5.2 +/- 0.7 mV under control conditions to 27.5 +/- 2.0 mV in the presence of the cytokine). These effects were mimicked by carbocyclic thromboxane A2 (10(-6) mol/l), a stable thromboxane A2 agonist. The TNF-alpha action was inhibited by 1-benzylimidazole (2 x 10(-4) mol/l), a thromboxane synthase inhibitor, and BAY U 3405 (5 x 10(-4) mol/l), an inhibitor of thromboxane receptors. Measurements of thromboxane production in the supernatant of the culture revealed an increased concentration of thromboxane B2, the stable metabolite of thromboxane A2, after exposure to TNF-alpha. Immuncytochemical staining for cyclooxygenase-2 (COX-2) and the neuronal marker microtubule-associating protein-2 revealed an upregulation of COX-2 in myenteric neurons after exposure to the cytokine. These results demonstrate the involvement of COX-2 and the subsequent production of thromboxane A2 in the presence of TNF-alpha.

Topics: Animals; Cyclooxygenase 2; Electrophysiology; Enzyme Induction; Enzyme-Linked Immunosorbent Assay; Inflammation; Intestine, Small; Membrane Potentials; Myenteric Plexus; Patch-Clamp Techniques; Prostaglandin-Endoperoxide Synthases; Rats; Thromboxane A2; Tumor Necrosis Factor-alpha; Up-Regulation

Thromboxane (TX) A2 is released from multiple cell types and is a prime mediator of the pathogenesis of many vascular events, including angiogenesis. Endothelial cells express TXA2 receptors (TP) but the effects of TP stimulation on angiogenesis remain controversial. In this study, we show that stimulation of endothelial cell TP impairs ligand-induced FGF receptor internalization and consequently abrogates FGF-2-induced endothelial cell migration in vitro and angiogenesis in vivo. Prevention of FGF-2-induced angiogenesis was associated with expression of the TPbeta isoform. The deficit in FGFR1 internalization was mediated through activation of TPbeta preventing the FGF-2-mediated decrease in p53 expression, thus enhancing thrombospondin-1 (TSP-1) release from EC and reducing FGFR1 internalization. Once released TSP-1 interacted with the alpha(v)beta3 integrin on the EC surface. On stimulation, FGFR1 and alpha(v)beta3 were found to associate in a complex. We determined that complex formation was important for receptor internalization as conditions that inhibit FGFR1 internalization, such as inappropriate ligation of alpha(v)beta3 by either TSP-1 or a neutralizing antibody, disrupted the complex. These results establish a novel role for isoform specific regulation of angiogenesis by TP, provide the first functional significance for the existence of two TP isoforms in humans, and clarify the mechanism by which TP signaling regulates FGFR1 kinetics and signaling.

Topics: Bridged Bicyclo Compounds, Heterocyclic; Cell Cycle; Cell Movement; Endocytosis; Endothelial Cells; Endothelium, Vascular; Fatty Acids, Unsaturated; Fibroblast Growth Factor 2; Humans; Hydrazines; Inflammation; Integrin alphaVbeta3; Ischemia; Ligands; Neovascularization, Physiologic; Protein Isoforms; Receptor Protein-Tyrosine Kinases; Receptor, Fibroblast Growth Factor, Type 1; Receptors, Fibroblast Growth Factor; Receptors, Thromboxane A2, Prostaglandin H2; Thrombospondin 1; Thromboxane A2; Transcription, Genetic; Tumor Suppressor Protein p53

Trypanosoma cruzi induces inflammatory reactions in several tissues. The production of prostaglandin F2alpha, 6-keto-prostaglandin F1alpha and thromboxane B2, known to regulate the immune response and to participate in inflammatory reactions, was studied in mice experimentally infected with T. cruzi. The generation of nitric oxide (NO), which could be regulated by cyclooxygenase metabolites, was also evaluated. In the acute infection the extension of inflammatory infiltrates in skeletal muscle as well as the circulating levels of cyclooxygenase metabolites and NO were higher in resistant C3H mice than in susceptible BALB/c mice. In addition, the spontaneous release of NO by spleen cells increased earlier in the C3H mouse strain. In the chronic infections, the tissue inflammatory reaction was still prominent in both groups of mice, but a moderate increase of thromboxane B2 concentration and in NO released by spleen cells was observed only in C3H mice. This comparative study shows that these mediators could be mainly related to protective mechanisms in the acute phase, but seem not to be involved in its maintenance in the chronic T. cruzi infections.

Topics: Acute Disease; Animals; Chagas Disease; Chronic Disease; Dinoprostone; Disease Susceptibility; Epoprostenol; Inflammation; Male; Mice; Mice, Inbred BALB C; Mice, Inbred C3H; Muscle, Skeletal; Nitric Oxide; Prostaglandin-Endoperoxide Synthases; Species Specificity; Spleen; Thromboxane A2; Thromboxane B2

Prostaglandins (PGs) and thromboxane (TX) are important mediators of inflammation. Recent studies revealed that PG and TX synthesis is controlled by the regulation of PG- and TX-synthesizing enzymes. In this study, we examined the TX synthesis and the expression of TX-synthesizing enzymes in activated peripheral polymorphonuclear leukocytes (PMNs) obtained from children with bacterial infection. Blood samples were obtained from controls and patients with bacterial infection. A23187-stimulated production of TXB(2), a stable metabolite of TXA(2) in PMNs, was measured by a specific radioimmunoassay. The mRNA expression of cytosolic phospholipase A(2) (cPLA(2)), cyclooxygenase (COX)-1, COX-2, and TXA(2) synthase was determined by RT-PCR. The synthesis of TXB(2) in PMNs was significantly increased in the patients [925.0 (550.0-1100.0) pg/10(6) cells], compared with the controls [550.0 (450.0-775.0) pg/10(6) cells]. The mRNA expression for cPLA(2) and COX-2 in PMNs was also enhanced in the patients. The results indicate that TX production in PMNs is significantly increased through possible transcriptional mechanisms of cPLA(2) and COX-2 during bacterial infection in children. The upregulation of TXA(2) synthesis may contribute to the process of acute inflammatory reaction caused by bacterial infection.

Topics: Adolescent; Anti-Bacterial Agents; Bacterial Infections; Calcimycin; Case-Control Studies; Child; Child, Preschool; Cyclooxygenase 1; Cyclooxygenase 2; Cytosol; Female; Humans; Infant; Inflammation; Isoenzymes; Male; Membrane Proteins; Neutrophils; Phospholipases A; Phospholipases A2; Prostaglandin-Endoperoxide Synthases; RNA, Messenger; Thromboxane A2; Thromboxane B2; Up-Regulation

Blood-derived monocytes are found at sites of inflammation as well as in solid tumors and atherosclerotic arteries. They are an abundant source of inflammatory eicosanoids such as prostaglandin E2 (PGE2) and thromboxane A2, which are formed via arachidonic acid (AA) metabolism by cyclooxygenase-1/2 (COX-1/2). In vitro studies of inflammatory mediator production are conducted invariably in room air, which does not reflect the oxygen tensions found in monocyte-containing lesions, which are frequently hypoxic. In this work we examined the effects of hypoxia at levels reported in these lesions, on monocyte COX-2 expression, the related events that lead to eicosanoid synthesis, and relationships with tumor necrosis factor (TNF)-alpha synthesis. In fresh human monocytes exposed to hypoxia (1% O2), there was an increase in COX-2 protein compared with cells in normoxia, and this was attributable to increased transcription and mRNA stability. However, the synthesis of PGE2 and thromboxane A2 was reduced in hypoxia and did not reflect the increased level of COX-2. Monocytes prelabeled with [3H]AA followed by lipopolysaccharide stimulation in the presence of hypoxia showed a reduced release of AA compared with cells in normoxia. In addition, hypoxia resulted in decreased phosphorylation of the p44/42 mitogen-activated protein kinase and of cytosolic phospholipase A2. Hypoxia also increased TNF-alpha synthesis, which appeared to play a role in COX-2 expression, and the observed increase TNF-alpha synthesis appeared to result from reduced PGE2 synthesis. Overall, the results suggest the existence of an autocrine loop of regulation between monocyte eicosanoid and TNF-alpha production, which is dysregulated in hypoxia and establishes hypoxia as being an important environmental determinant of inflammatory mediator production.

Topics: Blotting, Northern; Blotting, Western; Cyclooxygenase 2; Cytosol; Dinoprostone; Dose-Response Relationship, Drug; Eicosanoids; Enzyme-Linked Immunosorbent Assay; Genes, Reporter; Heme; Humans; Hypoxia; Inflammation; Interleukin-1; Isoenzymes; Lipopolysaccharides; Membrane Proteins; Mitogen-Activated Protein Kinase 1; Mitogen-Activated Protein Kinase 3; Mitogen-Activated Protein Kinases; Models, Biological; Monocytes; Oxygen; Phosphorylation; Promoter Regions, Genetic; Prostaglandin-Endoperoxide Synthases; RNA, Messenger; Thromboxane A2; Time Factors; Transfection; Tumor Necrosis Factor-alpha; U937 Cells; Zinc

The hypothesis was tested that CD40-CD154 interaction is involved in the induction of cyclooxygenase-2 and the release of prostanoids in human endothelial cells.. In a coculture model of human endothelial cells and a transfected CD154 positive cell line, engagement of CD40 on endothelial cells dramatically increased the synthesis of prostacyclin, prostaglandin E(2) and thromboxane A(2). This upregulation was mediated through an induction of cyclooxygenase-2 (Cox-2), as it was blocked by Cox-2-selective inhibitors. Western blot analysis demonstrated that Cox-2 protein was markedly increased in endothelial cells following CD40 engagement, an effect that was inhibited by pretreatment of cells with an anti-CD154 antibody.. The data indicate that signaling via CD40 constitutes a major pathway in human endothelial cells for the induction of Cox-2 and release of prostanoids. The CD40-Cox-2 axis thus may represent an important pathway for initiating or maintaining an inflammatory process at the vessel wall.

Topics: Blotting, Western; CD40 Antigens; Cells, Cultured; Coculture Techniques; Cyclooxygenase 2; Dinoprostone; Endothelium, Vascular; Enzyme Induction; Epoprostenol; Flow Cytometry; Humans; Inflammation; Isoenzymes; Membrane Proteins; Probability; Prostaglandin-Endoperoxide Synthases; Sensitivity and Specificity; Thromboxane A2; Up-Regulation

Human lung fibroblasts represent important targets for the biologic activities of bradykinin (BK). We have identified multiple mechanisms in these cells which may extend their potential for BK receptor responsiveness, particularly with regard to generation of arachidonate metabolites. These fibroblasts can constitutively express B2 and B1 BK receptors concurrently, both coupled to the pathway for arachidonate metabolism resulting in generation of PGE2 and the potent vasoactive lipid mediator Thromboxane A2. Although expression patterns for B2 and B1 receptors have classically been regarded as 'constitutive' and 'inducible', respectively, we demonstrate that in human lung fibroblasts both can be expressed spontaneously at equivalent biologic activity levels without selective induction by other mediators. Concurrent B2/B1 receptor expression extends the scope of fibroblast response potential to both BK and des-Arg9-BK in the same time frame. We have identified additional short-term and long-term cellular events, involving both protein kinase pathways through which BK receptors act and those which act upon BK receptors, that result in enhanced BK receptor response potential. These properties of BK receptors may affect whether fibroblast behaviors maintain controlled activities of normal homeostasis or foster escalating cellular responses which may influence the progression of certain human disease states.

Topics: Arachidonic Acid; Cell Line; Cyclic AMP-Dependent Protein Kinases; Dinoprostone; Fibroblasts; Humans; Inflammation; Kinetics; Lung; Phosphorylation; Protein Kinase C; Receptor, Bradykinin B1; Receptor, Bradykinin B2; Receptors, Bradykinin; Signal Transduction; Thromboxane A2

The cardiopulmonary response elicited by intravenous bacteria or endotoxin is well characterized in swine and has two major components. The first represents the acute pulmonary and broncho-constrictive phase (0-2 h) and the second phase (3-8 h) represents increased microvascular permeability, hypotension, and enhanced leukocyte-endothelial adhesion. The pulmonary vasoconstriction and bronchoconstriction of phase 1 results in acute pulmonary hypertension and airway dysfunction, which may result in rapid mortality. Because this acute pulmonary response may not mimic the development of human septic shock, we sought to block this early phase and examine the role of tumor necrosis factor in the latter septic phase (3-8 h). Employing a thromboxane A2 (TXA2) receptor antagonist (BAY U 3405) in the presence of LD100 Escherichia coli challenge, we blocked the acute pulmonary hypertensive phase and prevented early mortality, however, TXA2 blockade did not affect the latter development of septic shock and death. This latter lethal phase, characterized by prolonged leukopenia, was blocked in a dose-dependent manner by tumor necrosis factor monoclonal antibody. We conclude that the TXA2-blocked E. coli-challenged swine may provide a novel animal model in which to investigate the pathophysiology of acute septic shock.

Topics: Animals; Antibodies, Monoclonal; Bronchoconstriction; Capillary Permeability; Carbazoles; Disease Models, Animal; Dose-Response Relationship, Drug; Escherichia coli; Inflammation; Leukocytes; Leukopenia; Lung; Platelet Aggregation Inhibitors; Pulmonary Circulation; Receptors, Thromboxane; Shock, Septic; Sulfonamides; Swine; Thromboxane A2; Tumor Necrosis Factor-alpha; Vasoconstriction

Although it is well recognized that beta-blockers can induce bronchoconstriction only in patients with asthma, mechanisms of the bronchoconstriction are not well known. We hypothesize that bronchoconstriction induced by beta-blockers may result from inflammatory mediators released by allergic reactions. In this study, we developed a guinea pig model for propranolol-induced bronchoconstriction (PIB) after antigen inhalation and investigated the effect of specific thromboxane (TXA2) receptor antagonists, S-1452 and ONO NT-126, on PIB in passively sensitized and artificially ventilated guinea pigs to determine whether TXA2 is involved in PIB. Propranolol caused bronchoconstriction with 10 mg/ml of propranolol was inhaled 20 min after antigen challenge. On the other hand, propranolol did not produce bronchoconstriction after antigen provocation in nonsensitized guinea pigs or after saline provocation in sensitized animals. Pretreatment of the animals with S-1452 in doses of 0.01 and 0.1 mg/kg and ONO NT-126 in doses of 1.0 and 10 micrograms/kg injected intravenously 15 min after antigen challenge as well as before antigen challenge reduced PIB in a dose-dependent manner. Bronchoconstriction caused by methacholine did not induce PIB. These results suggest that TXA2 has an important role in the pathophysiology of the PIB that develops after the allergic bronchoconstriction.

Topics: Administration, Inhalation; Analysis of Variance; Animals; Asthma; Bridged Bicyclo Compounds; Bronchial Provocation Tests; Constriction, Pathologic; Disease Models, Animal; Dose-Response Relationship, Drug; Fatty Acids, Monounsaturated; Guinea Pigs; Hypersensitivity; Inflammation; Injections, Intravenous; Male; Methacholine Chloride; Premedication; Propranolol; Receptors, Prostaglandin; Thromboxane A2; Time Factors

1. To elucidate the role of acetylcholine and various autacoids in endothelin-1 (ET-1)-induced contraction in human bronchus, the effects of various receptor antagonists were examined. In addition, the ability of ET-1 to stimulate the release of histamine, peptidoleukotrienes and prostanoids was determined. 2. ET-1 was a potent and effective contractile agonist in human bronchus, possessing similar potency and efficacy to leukotriene D4 (LTD4); EC50 (-log M): ET-1 = 7.76 +/- 0.09, n = 7; LTD4 = 8.46 +/- 0.53, n = 7; P > 0.2; maximum response (% 10 microM pre-carbachol): ET-1 = 103.8 +/- 17.4, n = 7; LTD4 = 95.5 +/- 9.3, n = 7; P > 0.6. 3. The cyclo-oxygenase inhibitor, sodium meclofenamate (1 microM) or the potent and selective thromboxane receptor antagonist, SQ 29,548 (1 microM) were without significant effect on ET-1 concentration-response curves. 4. In the presence of sodium meclofenamate (1 microM), the muscarinic receptor antagonist, atropine (1 microM), the platelet activating factor (PAF) receptor antagonist, WEB 2086 (1 microM) or the combination of the H1-histamine receptor antagonist, mepyramine (10 microM) and the leukotriene receptor antagonist, SK&F 104353 (10 microM), were without marked effect on ET-1 concentration-response curves. In addition, the combination of all four receptor antagonists did not antagonize ET-1-induced contraction. 5. ET-1 (0.3 microM) did not stimulate the release of histamine or immunoreactive leukotrienes from human bronchus. 6. ET-1 (0.3 microM) significantly stimulated the release of prostaglandin D2 (PGD2), 9alpha, 11beta PGF2 (PGD2 metabolite), PGE2, 6-keto PGF1alpha (PGI2 metabolite), PGF2alpha, and thromboxane B2 (TxB2) a lower concentration, 10 nM, was without effect on prostanoid release. The production of PGD2 was increased 7.5 fold, whereas the release of the other prostanoids was stimulated only about 1.6 to 2.7 fold.7. These data provide evidence that ET-1 elicits contraction of human isolated bronchus predominantly via a direct mechanism with no significant involvement of the release of acetylcholine, leukotrienes,histamine or PAF. Although ET-1 increased the release of several prostanoids they did not have a significant modulatory effect on the smooth muscle contraction.

Topics: Acetylcholine; Azepines; Bridged Bicyclo Compounds, Heterocyclic; Bronchi; Dicarboxylic Acids; Endothelins; Fatty Acids, Unsaturated; Histamine Release; Humans; Hydrazines; In Vitro Techniques; Indomethacin; Inflammation; Leukotrienes; Lung; Meclofenamic Acid; Muscle Contraction; Muscle, Smooth; Platelet Aggregation Inhibitors; Prostaglandins; Spectrometry, Fluorescence; SRS-A; Thromboxane A2; Triazoles

Systemic injection of bacterial endotoxin (Lipopolysaccharide, LPS) in experimental animals induces anterior uveitis without major pathological changes in other organs. The present study investigates the effect of LPS on production of inflammatory mediators in cultured bovine pigmented ciliary epithelial cells (CB-cells) by means of radioimmunoassays and bioassays. LPS was found to stimulate CB-cells to secrete prostaglandin E2 and prostacyclin (assayed as its stable metabolite 6-keto-prostaglandin F1a), but not leukotriene B4 or thromboxane A2 (assayed as its stable metabolite thromboxane B2). CB-cells produced membrane-associated interleukin 1-activity in response to LPS, but no tumor necrosis factor-activity was found after challenge of CB-cells with LPS. The direct effect of LPS on production of inflammatory mediators by cells from the anterior uvea could play a role in the pathophysiology of endotoxin-induced uveitis.

Topics: Animals; Cattle; Cells, Cultured; Ciliary Body; Dinoprostone; Epithelium; Epoprostenol; Inflammation; Interleukin-1; Leukotriene B4; Lipopolysaccharides; Radioimmunoassay; Thromboxane A2; Tumor Necrosis Factor-alpha; Uveitis

Several [(1H-imidazol-1-yl)methyl]- and [(3-pyridinyl)methyl] pyrroles were prepared and evaluated in vitro as thromboxane synthetase inhibitors in human platelet aggregation studies. A number of structures, e.g. 10b,f,g,i (respective IC50 values: 1 microM, 50 nM, 42 nM, 44 nM) showed superior in vitro inhibition of TXA2 synthetase when compared to the standard dazoxiben (1). However, it was found that in vitro potency did not translate into nor correlate with in vivo activity when these compounds were evaluated in mice in a collagen-epinephrine-induced pulmonary thromboembolism model. (E)-1-Methyl-2-[(1H-imidazol-1-yl)methyl]-5-(2-carboxyprop-1-enyl) pyrrole (10b) was found to offer protection against collagen-epinephrine-induced mortality in mice, thereby demonstrating that oral administration is an effective route for absorption of this drug. Additional evidence for the oral effectiveness of 10b in lowering serum TXB2 levels was obtained by performing ex vivo radioimmunoassay experiments with rats. A 13-week study of 10b in rats with reduced renal mass was conducted in order to evaluate the role of TXA2 production in hypertension and renal dysfunction. Although serum and urinary TXB2 levels in rats were found to be lowered during this study by 10b, the levels of urinary protein excretion remained comparable to that of the control group.

Topics: Animals; Aorta; Biological Availability; Blood Platelets; Chemical Phenomena; Chemistry; Humans; Imidazoles; Inflammation; Kidney Diseases; Male; Mice; Microsomes; Platelet Aggregation Inhibitors; Prostaglandin Endoperoxides, Synthetic; Prostaglandin H2; Prostaglandins H; Pyridines; Pyrroles; Rats; Structure-Activity Relationship; Swine; Thromboxane A2; Thromboxane B2; Thromboxane-A Synthase

Anesthetized, intubated, and mechanically ventilated rabbits were exposed to aerosolized saline, cotton dust extract (CDE), or tannin for 5 minutes and lavaged 4 hours after exposure. Cell numbers and types present in the bronchoalveolar lavage fluid (BALF) were determined and the concentrations of thromboxane A2 (TxA2) and prostaglandin F2-alpha (PGF2-alpha) in the BALF were also analyzed. The saline control animals had increased numbers and percentage of polymorphonuclear leukocytes (PMN) in the BALF as well as increased levels of TxB2 and PGF2-alpha compared with unexposed animals. Exposure to CDE further increased the number and percentage of PMN and the level of PGF2-alpha but had no effect on TxA2 levels when compared with control animals. Tannin exposure increased PGF2-alpha levels to the same extent as CDE exposure. PMN also increased but to a lesser extent than with CDE. These results indicate that the inflammatory response to CDE is only partially due to the tannin present in CDE.

Topics: Animals; Byssinosis; Chemotactic Factors; Dinoprost; Gossypium; Inflammation; Lung; Neutrophils; Rabbits; Respiratory Hypersensitivity; Tannins; Therapeutic Irrigation; Thromboxane A2

Topics: Biopsy, Needle; Graft Rejection; Humans; Inflammation; Kidney Diseases; Kidney Transplantation; Macrophages; Monocytes; Thromboxane A2; Thromboxane B2

Topics: Capillary Permeability; Dinoprostone; Epoprostenol; Humans; Inflammation; Migraine Disorders; Pain; Prostaglandins; Prostaglandins E; Thromboxane A2; Vasoconstriction; Vasodilation

Topics: Dietary Fats; Eicosapentaenoic Acid; Epoprostenol; Humans; Inflammation; Leukocytes; Leukotriene B4; Myocardial Infarction; Thrombosis; Thromboxane A2

Unilateral ureter obstruction induces an exaggerated prostaglandin release from isolated perfused rabbit kidneys in response to vasoactive peptides. Perfused hydronephrotic kidneys also exhibit the release of thromboxane A2 which is not detected with normal or contralateral kidneys. Reversal of the ureteral obstruction causes a decreased production of PGs and TxA2 in response to bradykinin. Morphological examination of the HNK demonstrates an enlarged interstitial space containing a fibroblast-like cell and the presence of mononuclear cells. Administration of endotoxin to the perfused HNK elicits the release of PGE2 and TxB2 consistent with the ability of endotoxin to stimulate arachidonic acid metabolism in cultured macrophage. Rabbit CLK and the cat HNK, which are deficient in macrophages, exhibit minimal PGE2 and no detectable TxA2 release after endotoxin stimulation. Cells cultured from the rabbit HNK cortex contain fibroblast-like cells and phagocytic cells which respond to BK with a profound PG production. Conditioned media from mononuclear cells have been shown by others to stimulate PGE2 production from fibroblasts. Other models of renal disease (renal venous constriction and glycerol-induced tubular necrosis) exhibit exaggerated PG and TxA2 release and facilitated cortical microsomal AA metabolism. These data suggest that proliferation of fibroblast-like cells and the presence of mononuclear cells may be involved in this exaggerated PG and TxA2 production underlying renal injury.

Topics: Animals; Biological Assay; Bradykinin; Cells, Cultured; Dinoprostone; Endotoxins; Functional Laterality; Hydronephrosis; Inflammation; Kidney; Kidney Cortex; Kidney Medulla; Male; Prostaglandins E; Rabbits; Thromboxane A2; Thromboxanes; Ureteral Obstruction

A bolus injection of a very low dose (100 ng) of endotoxin into an isolated perfused hydronephrotic (3 day unilateral ureter obstructed) kidney resulted in the appearance of substances in the venous effluent, which caused a biphasic chronic contraction of intestinal and vascular smooth muscle bioassay strips. Indomethacin pretreatment blocked the effect. The contralateral (unobstructed) rabbit kidney, postobstructed hydronephrotic rabbit kidney (i.e., release of ureter obstruction for 3-10 days) and the hydronephrotic cat kidney did not respond to endotoxin. Histological examination demonstrated that the hydronephrotic rabbit kidney contains mononuclear cells, whereas the unobstructed contralateral rabbit kidney as well as the postobstructed rabbit hydronephrotic kidney and the hydronephrotic cat kidney have considerably fewer mononuclear cells. The responsiveness of the hydronephrotic rabbit kidney to endotoxin is dependent on ex vivo perfusion time and is suppressed by inhibition of protein synthesis with cycloheximide. These data suggest that ureter obstruction in the rabbit stimulates the infiltration of macrophages which are sensitive to endotoxin and which participate in the exaggerated prostaglandin production.

Topics: Animals; Arachidonic Acid; Arachidonic Acids; Cats; Dinoprostone; Endotoxins; Inflammation; Macrophages; Male; Prostaglandins; Prostaglandins E; Rabbits; Thromboxane A2; Thromboxane B2; Thromboxanes; Ureteral Obstruction

Fenflumizole (2-(2,4-difluorophenyl)-4,5-bis(4-methoxyphenyl)imidazole), a new non-steroidal anti-inflammatory agent, was investigated for interference with cyclo-oxygenase activity in vivo, ex vivo and in vitro in comparison with indomethacin (and aspirin). Fenflumizole was comparable to indomethacin ex vivo in inhibition of thromboxane (TX)A2 production in rabbit platelets and inhibition of prostaglandin (PG)I2 (approximately prostacyclin) generation in rabbit mesenteric arteries and in vivo as an inhibitor of PGE2 formation in inflammatory exudates in rats. Fenflumizole was 18 times less active than indomethacin in inhibition of PGE2 synthesis in vitro and 170 times weaker as an inhibitor of PGI2 generation in the rat stomach mucosa ex vivo. Fenflumizole was 20-50 times more potent than indomethacin in vivo in inhibition of arachidonic acid induced bronchoconstriction in guinea-pigs, in inhibition of platelet aggregation on tendons superfused with blood from rabbits and in vitro in inhibition of aggregation of human and rabbit platelets. Neither fenflumizole nor indomethacin inhibited TXA2-synthetase in vitro. Aspirin-when tested-was less potent than fenflumizole and indomethacin. It is concluded that fenflumizole is a potent cyclo-oxygenase inhibitor. The very potent activity of fenflumizole against platelet aggregation and bronchoconstriction suggests a selectivity in the mode of action. The weak inhibition of gastric PGI2 generation may account for the previously observed weak gastro-ulcerogenicity of fenflumizole.

Topics: Animals; Arachidonic Acids; Aspirin; Blood Platelets; Cattle; Cyclooxygenase Inhibitors; Dinoprostone; Drug Interactions; Epoprostenol; Exudates and Transudates; Guinea Pigs; Imidazoles; In Vitro Techniques; Indomethacin; Inflammation; Male; Platelet Aggregation; Prostaglandins E; Rabbits; Rats; Rats, Inbred Strains; Thromboxane A2

Unilateral ureter obstruction in rabbits produced profound changes in endogenous and exogenous renal arachidonic acid metabolism. Isolated perfused hydronephrotic kidneys (removed after 3 or 10 d of ureter obstruction) responded to bradykinin stimulation with a markedly enhanced release of prostaglandin E2 and thromboxane A2. Reversal (3 or 10 d) of the ureter obstruction resulted in a reduction in the vasoactive peptide-induced release of prostaglandin E2 and thromboxane A2 from the perfused hydronephrotic kidney. However, postobstruction reversal of prostaglandin production by the agonist-stimulated perfused kidney was not reflected in the cortical microsomal cyclooxygenase activity, which is greatly enhanced during ureter obstruction and does not decrease after removal of the obstruction. Histological analysis of the renal cortex in rabbits with ureteral obstruction revealed a proliferation of fibroblast-like cells and the presence of mononuclear cells; removal of the obstruction did not result in a disappearance of cortical fibroblasts but did result in a decrease of monocytes. The critical involvement of mononuclear cells in the exaggerated arachidonate metabolism that occurs during hydronephrosis was exhibited by the demonstration that: (a) only the perfused hydronephrotic rabbit kidney responded to administration of endotoxin with a sustained release of prostaglandin E2 and thromboxane A2; (b) the contralateral rabbit kidney, which is devoid of mononuclear cells, did not respond to endotoxin; and (c) the hydronephrotic cat kidney, which exhibits a fibroblast proliferation with a low number of mononuclear cells, did not respond to endotoxin. Thus, proliferation of fibroblast-like cells and the presence of mononuclear cells appear to be involved in the exaggerated prostaglandin and thromboxane production underlying hydronephrosis. The increase in microsomal cyclooxygenase activity is apparently most closely correlated with the increased fibroblastic activation and cellularity, whereas mononuclear cells (possibly via monokines) seem to be critical for the markedly enhanced prostaglandin and thromboxane release induced by endotoxin and bradykinin.

Topics: Animals; Arachidonic Acids; Bradykinin; Cats; Disease Models, Animal; Endotoxins; Fibroblasts; Inflammation; Microsomes; Monocytes; Prostaglandins E; Rabbits; Thromboxane A2; Thromboxanes; Ureteral Obstruction

Topics: Anti-Inflammatory Agents; Epoprostenol; Humans; Inflammation; Prostaglandin Endoperoxides; Prostaglandins; Thromboxane A2

Topics: 8,11,14-Eicosatrienoic Acid; Arachidonic Acids; Blood Platelets; Colchicine; Feedback; Humans; Immunity; Inflammation; Melatonin; Prostaglandins; Prostaglandins E; Thromboxane A2

Topics: Animals; Aorta; Arachidonic Acids; Calcitonin; Guinea Pigs; In Vitro Techniques; Inflammation; Kinetics; Lung; Male; Muscle Contraction; Muscle, Smooth, Vascular; Prostaglandin Antagonists; Prostaglandins; Thromboxane A2

Rat platelet rich plasma (PRP) generates prostaglandin endoperoxide-like activity, thromboxane A2 (TXA2) and stable prostaglandins (PGs) after collagen addition. Of the stable PGs, PGE is the main product and its formation is related to the dose of collagen. Indomethacin and eicosatetraynoic acid (TYA), both cyclo-oxygenase inhibitors, inhibit TXA2 and PGE formation simultaneously. PRP of essential fatty acid deficient (EFAD) rats, however, generates far less PG-endoperoxide like activity, TXA2 and PGE, though the release of serotonin (5-HT) is unaltered. In normal rats a marked inhibition of the cyclo-oxygenase by TYA also has no effect on 5-HT release. For these 2 reasons the role of PG endoperoxides and TXA2 seems to be unimportant for the 5-HT release reaction. The diminished biosynthesis of PGs and TXA2 in EFAD PRP is not due to an impaired cyclo-oxygenase activity since addition of AA causes an equal formation of PGE in both types of PRP. The use of platelets as in-vitro model for testing anti-inflammatory activity of drugs is discussed. The results, obtained with platelets support the hypothesis that the main reason for the decreased acute inflammatory reaction in EFAD rats is a diminished supply of endogenous PG precursors.

Topics: Animals; Arachidonic Acids; Blood Platelets; Collagen; Fatty Acids, Essential; Indomethacin; Inflammation; Male; Platelet Aggregation; Prostaglandins; Prostaglandins E; Rats; Serotonin; Thromboxane A2; Thromboxanes