l-663536 and Reperfusion-Injury

Oxidative stress is considered a key factor contributing to the initiation and development of cardiac injury following ischaemia‒reperfusion (I/R). Arachidonate 5-lipoxygenase (ALOX5) is a rate-limiting enzyme for leukotriene biosynthesis. MK-886 is an inhibitor of ALOX5 that exhibits anti-inflammatory and antioxidant activities. However, the significance of MK-886 in preventing I/R-mediated cardiac injury and the underlying mechanism remain unclear. Cardiac I/R model was produced by ligation/release of the left anterior descending artery. MK-886 (20 mg/kg) was administered intraperitoneally into mice at 1 and 24 h before I/R. Our results indicated that MK-886 treatment significantly attenuated I/R-mediated cardiac contractile dysfunction and decreased the infarct area, myocyte apoptosis, and oxidative stress accompanied with reduction of Kelch-like ECH-associated protein 1 (keap1) and upregulation of nuclear factor erythroid 2-related factor 2 (NRF2). Conversely, administration of the proteasome inhibitor epoxomicin and NRF2 inhibitor ML385 greatly abrogated MK-886-mediated cardioprotection after I/R injury. Mechanistically, MK-886 enhanced the expression of the immunoproteasome subunit β5i, which interacted with keap1 and enhanced its degradation, leading to activation of the NRF2-dependent antioxidant response and improvement of mitochondrial fusion-fission balance in the I/R-treated heart. In summary, our present findings indicated that MK-886 could protect the heart against I/R injury and highlight that MK-886 may represent a promising therapeutic candidate for preventing ischaemic disease.

Topics: Animals; Antioxidants; Apoptosis; Kelch-Like ECH-Associated Protein 1; Mice; NF-E2-Related Factor 2; Oxidative Stress; Proteasome Endopeptidase Complex; Reperfusion Injury

Traditional Chinese medicine Tongxinluo (TXL) has been widely used to treat coronary artery disease in China, since it could reduce myocardial infarct size and ischemia/reperfusion injury in both non-diabetic and diabetic conditions. It has been shown that TXL could regulate peroxisome proliferator activated receptor-α (PPAR-α), a positive modulator of angiopoietin-like 4 (Angptl4), in diabetic rats. Endothelial junction substructure components, such as VE-cadherin, are involved in the protection of reperfusion injury. Thus, we hypothesized cell-intrinsic and endothelial-specific Angptl4 mediated the protection of TXL on endothelial barrier under high glucose condition against ischemia/reperfusion-injury via PPAR-α pathway.. Incubated with high glucose medium, the human cardiac microvascular endothelial cells (HCMECs) were then exposed to oxygen-glucose-serum deprivation (2 hours) and restoration (2 hours) stimulation, with or without TXL, insulin, or rhAngptl4 pretreatment.. TXL, insulin, and rhAngptl4 had similar protective effects on the endothelial barrier. TXL treatment reversed the endothelial barrier breakdown in HCMECs significantly as identified by decreasing endothelial permeability, upregulating the expression of JAM-A, VE-cadherin, and integrin-α5 and increasing the membrane location of VE-cadherin and integrin-α5, and these effects of TXL were as effective as insulin and rhAngptl4. However, Angptl4 knock-down with small interfering RNA (siRNA) interference and PPAR-α inhibitor MK886 partially abrogated these beneficial effects of TXL. Western blotting also revealed that similar with insulin, TXL upregulated the expression of Angptl4 in HCMECs, which could be inhibited by Angptl4 siRNA or MK886 exposure. TXL treatment increased PPAR-α activity, which could be diminished by MK886 but not by Angptl4 siRNA.. These data suggest cell-intrinsic and endothelial-specific Angptl4 mediates the protection of TXL against endothelial barrier breakdown during oxygen-glucose-serum deprivation and restoration under high glucose condition partly via the PPAR-α/Angptl4 pathway.

Topics: Angiopoietin-Like Protein 4; Cadherins; Capillary Permeability; Cell Adhesion Molecules; Cells, Cultured; Coronary Vessels; Drugs, Chinese Herbal; Endothelial Cells; Endothelium; Gene Knockdown Techniques; Glucose; Humans; Indoles; Insulin; Integrin alpha5; Lipoxygenase Inhibitors; Microvessels; Oxygen; PPAR alpha; Receptors, Cell Surface; Reperfusion Injury; Signal Transduction

Acute renal failure (ARF) is an important clinical problem with a high mortality and morbidity. One of the primary causes of ARF is ischemia/reperfusion (I/R). Inflammatory process and oxidative stress are thought to be the major mechanisms causing I/R. MK-886 is a potent inhibitor of leukotrienes biosynthesis which may have anti-inflammatory and antioxidant effects through inhibition of polymorphonuclear leukocytes (PMNs) infiltration into renal tissues. 3, 5-diiodothyropropionic acid (DITPA) have evidences of improving effects on I/R in heart through modulation of cellular signaling in response to ischemic stress. The objective of present study was to assess the effects of MK-886 and DITPA on renal I/R injury.. A total of 24 Adult males of Swiss albino mice were randomized to four groups: I/R group (n = 6), mice underwent 30 minute bilateral renal ischemia and 48 hr reperfusion. Sham group (n = 6), mice underwent same anesthetic and surgical procedures except for ischemia induction. MK-886-treated group: (n = 6), I/R + MK-886 (6 mg/kg) by intraperitoneal injection. DITPA-treated group: (n = 6), I/R + DITPA (3.75 mg/kg) by intraperitoneal injection.After the end of reperfusion phase mice were sacrificed, blood samples were collected directly from the heart for determination of serum TNF-a, IL-6, urea and Creatinine. Both kidney were excised, the right one homogenized for oxidative stress parameters (MDA and GSH) measurements and the left kidney fixed in formalin for histological examination.. Serum TNF-α, IL-6, urea and Creatinine, kidney MDA levels and scores of histopathological changes were significantly (P < 0.05) elevated in I/R group as compared with that of sham group. Kidney GSH level was significantly (P < 0.05) decreased in I/R group as compared with that of sham group. MK-886 treated group has significantly (P < 0.05) lowered levels of all study parameters except for GSH level which was significantly (P < 0.05) higher as compared with that of I/R group. DITPA caused non-significant (P > 0.05) changes in levels of all study parameters as compared with that of I/R group.. The results of the present study show that MK-886 significantly ameliorated kidney damage that resulted from I/R. For DITPA, as its administration might not be successful, administration using a different protocol may give different effects on I/R.

Topics: Animals; Cytokines; Diiodothyronines; Indoles; Kidney; Leukotriene Antagonists; Lipoxygenase Inhibitors; Male; Mice; Propionates; Reperfusion Injury; Thyroid Hormones; Treatment Outcome

Hepatic ischemia-reperfusion injury (I/R) may occur in transplantation, trauma, and elective hepatic resections. Leukotrienes have been shown to play a major role in hepatic I/R injury. Five-lipoxygenase enzyme is an important enzyme in the production of leukotrienes from arachidonic acid. MK-886 is an inhibitor of 5-lipoxygenase, and montelukast is a cysteinyl leukotriene receptor antagonist. The aim of this study was to investigate whether MK-886 and montelukast are effective in preventing hepatic I/R injury.. Rats were divided into five groups consisting of seven rats in each: (1) Control I/R, (2) Control-montelukast, (3) Control-MK-886, (4) I/R+montelukast, and (5) I/R+MK-886. Thirty min of total hepatic vascular occlusion and then 60 min reperfusion were performed to animals in groups 1, 4, and 5. In groups 2 and 4, montelukast, and in groups 3 and 5, MK-886 was applied intraperitoneally before and during the surgical procedures.. Apoptosis in the liver and intestine decreased significantly in the I/R+montelukast and I/R+MK-886 groups compared with the I/R group. Tissue malondialdehyde levels and glutathione consumptions also decreased significantly in the I/R+montelukast and I/R+MK-886 groups compared with the I/R group. The difference in serum alanine aminotransferase and aspartate aminotransferase levels between the groups did not reach significance.. Montelukast and MK-886 were found to be effective in prevention of liver and intestine injury by reducing apoptosis and oxidative stress in a hepatic I/R model. Anti-inflammatory properties and inhibition of lipid peroxidation by montelukast and MK-886 could be protective for these organs in I/R injury.

Topics: Acetates; Animals; Cyclopropanes; Disease Models, Animal; Indoles; Leukotriene Antagonists; Lipoxygenase Inhibitors; Liver Diseases; Male; Quinolines; Rats; Rats, Wistar; Reperfusion Injury; Sulfides

Rat gastric mucosal damage was induced by ischemia-reperfusion. The 5-lipoxygenase inhibitors MK886 and A63162, the 12-lipoxygenase inhibitor baicalein, the 15-lipoxygenase inhibitor PD146176 and the lipoxin (LX) A(4)/annexin 1 antagonist Boc1 increased mucosal damage in a dose-dependent manner. Low doses of these compounds, which have no effects on mucosal integrity, cause severe damage when combined with low doses of indomethacin, celecoxib or dexamethasone. 16,16-Dimethylprostaglandin (PG) E(2) and LXA(4) can replace each other in preventing mucosal injury induced by either cyclooxygenase or lipoxygenase inhibitors. The results suggest that not only cyclooxygenases, but also lipoxygenases have a role in limiting gastric mucosal damage during ischemia-reperfusion.

Topics: 16,16-Dimethylprostaglandin E2; Acetamides; Animals; Annexins; Anti-Ulcer Agents; Celecoxib; Cyclooxygenase Inhibitors; Dexamethasone; Drug Synergism; Flavanones; Fluorenes; Gastric Mucosa; Glucocorticoids; Indoles; Indomethacin; Lipoxygenase; Lipoxygenase Inhibitors; Male; Oligopeptides; Phenyl Ethers; Prostaglandin Antagonists; Pyrazoles; Rats; Rats, Wistar; Receptors, Formyl Peptide; Receptors, Lipoxin; Reperfusion Injury; Sulfonamides

Topics: Animals; Eicosanoids; Hydantoins; Indoles; Leukotriene Antagonists; Liver Transplantation; Male; Methacrylates; Platelet Aggregation Inhibitors; Rats; Rats, Inbred Lew; Receptors, Thromboxane; Reperfusion Injury; Thromboxane A2; Thromboxane-A Synthase

Topics: Animals; Eicosanoids; Endothelium, Vascular; Epoprostenol; Iloprost; Indoles; Indomethacin; Leukotriene Antagonists; Leukotrienes; Liver; Liver Transplantation; Reperfusion Injury

A common feature to most models of ischemia-reperfusion injury is the accumulation of polymorphonuclear leukocytes (PMNs) into the post-ischemic tissue during the reperfusion period. Interventions that lead to decreased PMN infiltration protect against tissue injury and therefore a knowledge of the chemotactic mediators leading to PMN accumulation is essential to understanding the pathogenesis of the injury and to the development of successful therapeutic strategies. Leukotriene B4 (LTB4), a metabolite formed via the 5-lipoxygenase pathway from arachidonic acid, is one of the most potent chemotactic mediators known. We have investigated the formation of LTB4 in a well characterized model of hepatic ischemia-reperfusion injury in the rat and made use of a specific leukotriene biosynthesis inhibitor, L663,536, to determine the importance of LTB4 in the pathogenesis of the injury. LTB4 concentrations were measured with a specific and sensitive gas chromatographic-mass spectrometric method previously developed in our laboratory. In liver tissue LTB4 levels were below the detection limit of 20 pg/g before 45 min ischemia and did not increase during the first 6 h of reperfusion. However, at 15 h and 24 h reperfusion LTB4 concentrations had increased to levels 50-fold those in control liver (867 +/- 267 pg/g). The increase of plasma alanine aminotransferase (ALT) activities indicated two phases of injury, an initial phase during the first few hours of reperfusion, and a second more severe injury phase between 6 h and 24 h reperfusion. PMNs accumulated in tissue throughout the reflow period reaching 700 +/- 49 per 50 high power fields (HPF) at 24 h.(ABSTRACT TRUNCATED AT 250 WORDS)

Topics: Alanine Transaminase; Animals; Indoles; Leukotriene B4; Liver; Male; Neutrophils; Rats; Rats, Inbred F344; Reperfusion Injury

Topics: Animals; Capillaries; Cricetinae; Indoles; Leukotriene Antagonists; Lipoxygenase Inhibitors; Mesocricetus; Reperfusion; Reperfusion Injury; Skin

Several studies have demonstrated that granulocytes accumulate in the intestinal mucosa following ischemia/reperfusion. It has been suggested that leukotriene B4 may be released during ischemia/reperfusion and consequently may promote granulocyte infiltration into the mucosa. The objectives of this study were to determine whether (a) leukotriene B4 is produced in the gut mucosa during ischemia and reperfusion, and (b) inhibition of leukotriene B4 attenuates granulocyte infiltration into the postischemic intestinal mucosa. Isolated segments of cat intestine were subjected to 3 hours of ischemia and 1 hour of reperfusion. Mucosal samples were obtained during baseline, ischemia at 3 hours and reperfusion at 1 hour. Leukotriene B4 production was determined by radioimmunoassay. Tissue-associated myeloperoxidase activity was used to quantitate granulocyte accumulation in the mucosal samples. In untreated animals, mucosal leukotriene B4 concentration was higher at reperfusion compared with baseline levels. The reperfusion-induced increase in mucosal leukotriene B4 was entirely prevented by pretreatment with either nordihydroguaiaretic acid (Sigma Chemical Co., St. Louis, MO) or L663,536 (Merck-Frosst, Montreal, Quebec, Canada), two potent lipoxygenase inhibitors. Both lipoxygenase inhibitors, as well as leukotriene B4 antagonist (SC-41930) significantly attenuated the reperfusion-induced infiltration of granulocytes. These results indicate that leukotriene B4 plays an important role in mediating the granulocyte accumulation elicited by reperfusion of the ischemic bowel.

Topics: Analysis of Variance; Animals; Benzopyrans; Cats; Granulocytes; Indoles; Intestinal Mucosa; Ischemia; Leukotriene B4; Masoprocol; Radioimmunoassay; Reperfusion Injury