atrial-natriuretic-factor and Acute-Lung-Injury

Topics: Acute Lung Injury; Animals; Atrial Natriuretic Factor; Cytokines; Lung; Mice; Mice, Knockout; Mice, Transgenic; Neutrophil Infiltration; Receptors, Atrial Natriuretic Factor

The effect of intratracheal lipopolysaccharide (LPS) instillation on right ventricular dysfunction in rats was studied with the aim of exploring underlying mechanisms.. A single dose of LPS (10 mg/kg) or an equal volume of saline was instilled intratracheally and lung injury evaluated using histopathologic scoring and wet/dry (W/D) weight ratio at 6 or 12 h post-administration. Besides, serum atrial natriuretic peptide (ANP) was detected using an enzyme-linked immunosorbent assay (ELISA) and right ventricle β-myosin heavy chain (β-MHC) presence was examined using reverse transcription polymerase chain reaction (RT-PCR). Echocardiography examined pulmonary artery acceleration time (PAAT), right ventricular free wall thickness (RVFWT), tricuspid annular plane systolic excursion (TAPSE), and right ventricular end-diastolic diameter (RVEDD). In addition, right ventricular TUNEL staining and Western blots of Bax and Bcl-2 were performed. Right ventricle and left ventricle caspases-3, -8, and -9 activity were examined using fluorometric assay. Finally, right ventricle myeloperoxidase (MPO) neutrophil staining, and right ventricle and plasma cytokines TNF-α, IL-1β, IL-6 detection was performed.. Histopathologic lung injury and increased W/D weight ratio was seen at 6 h after LPS intratracheal instillation, along with increased ANP, but not β-MHC. Pulmonary hypertension was indicated by decreased PAAT at 6 h post-exposure. Right ventricular systolic dysfunction and dilation were observed at 12 h post-exposure, as indicated by a significant decrease of TAPSE and increase of RVEDD. Of note, the procedure led to an increased right ventricle TUNEL positive cardiomyocytes, an increased Bax/Bcl-2 ratio, and increased right and left ventricle caspases-3, -8, and -9 activity as early as 6 h post-exposure, which was paralleled by increased right ventricle MPO staining and increased expression of right ventricle and serum cytokines TNF-α, IL-1β, and IL-6.. As well as acute lung injury, a single dose of LPS intratracheally instilled can induce pulmonary hypertension at 6 h post-exposure, with obvious right ventricular systolic dysfunction and right ventricular dilation present at 12 h post-exposure, possibly via cardiomyocytes apoptosis and inflammation.

Topics: Acute Lung Injury; Animals; Apoptosis; Atrial Natriuretic Factor; bcl-2-Associated X Protein; Caspases; Cytokines; Disease Models, Animal; Heart Ventricles; Inflammation; Lipopolysaccharides; Male; Myocytes, Cardiac; Neutrophils; Rats, Sprague-Dawley; Up-Regulation; Ventricular Dysfunction, Right

Microtubule (MT) dynamics is involved in a variety of cell functions, including control of the endothelial cell (EC) barrier. Release of Rho-specific nucleotide exchange factor GEF-H1 from microtubules activates the Rho pathway of EC permeability. In turn, pathologic vascular leak can be prevented by treatment with atrial natriuretic peptide (ANP). This study investigated a novel mechanism of vascular barrier protection by ANP via modulation of GEF-H1 function. In pulmonary ECs, ANP suppressed thrombin-induced disassembly of peripheral MT and attenuated Rho signaling and cell retraction. ANP effects were mediated by the Rac1 GTPase effector PAK1. Activation of Rac1-PAK1 promoted PAK1 interaction with the Rho activator GEF-H1, inducing phosphorylation of total and MT-bound GEF-H1 and leading to attenuation of Rho-dependent actin remodeling. In vivo, ANP attenuated lung injury caused by excessive mechanical ventilation and TRAP peptide (TRAP/HTV), which was further exacerbated in ANP(-/-) mice. The protective effects of ANP against TRAP/HTV-induced lung injury were linked to the increased pool of stabilized MT and inactivation of Rho signaling via ANP-induced, PAK1-dependent inhibitory phosphorylation of GEF-H1. This study demonstrates a novel protective mechanism of ANP against pathologic hyperpermeability and suggests a novel pharmacological intervention for the prevention of increased vascular leak via PAK1-dependent modulation of GEF-H1 activity.

Topics: Actins; Acute Lung Injury; Animals; Atrial Natriuretic Factor; Capillary Permeability; Cytoprotection; Disease Models, Animal; Endothelial Cells; Genes, Dominant; HEK293 Cells; Humans; Lung; Mice; Mice, Inbred C57BL; Microtubules; Models, Biological; Myosin Light Chains; p21-Activated Kinases; Phosphorylation; Pneumonia; Protein Binding; rac1 GTP-Binding Protein; Rho Guanine Nucleotide Exchange Factors; Thrombin

Oxidant injury contributes to acute lung injury (ALI). We previously reported that activation of protein kinase GI (PKGI) posttranscriptionally increased the key antioxidant enzymes catalase and glutathione peroxidase 1 (Gpx-1) and attenuated oxidant-induced cytotoxicity in mouse lung microvascular endothelial cells (MLMVEC). The present studies tested the hypothesis that the antioxidant effect of PKGI is mediated via inhibition of the c-Abl tyrosine kinase. We found that activation of PKGI with the cGMP analog 8pCPT-cGMP inhibited c-Abl activity and decreased c-Abl expression in wild-type but not PKGI(-/-) MLMVEC. Treatment of wild-type MLMVEC with atrial natriuretic peptide also inhibited c-Abl activation. Moreover, treatment of MLMVEC with the c-Abl inhibitor imatinib increased catalase and GPx-1 protein in a posttranscriptional fashion. In imatinib-treated MLMVEC, there was no additional effect of 8pCPT-cGMP on catalase or GPx-1. The imatinib-induced increase in antioxidant proteins was associated with an increase in extracellular H2O2 scavenging by MLMVEC, attenuation of oxidant-induced endothelial barrier dysfunction, and prevention of oxidant-induced endothelial cell death. Finally, in the isolated perfused lung, imatinib prevented oxidant-induced endothelial toxicity. We conclude that cGMP, through activation of PKGI, inhibits c-Abl, leading to increased key antioxidant enzymes and resistance to lung endothelial oxidant injury. Inhibition of c-Abl by active PKGI may be the downstream mechanism underlying PKGI-mediated antioxidant signaling. Tyrosine kinase inhibitors may represent a novel therapeutic approach in oxidant-induced ALI.

Topics: Active Transport, Cell Nucleus; Acute Lung Injury; Animals; Apoptosis; Atrial Natriuretic Factor; Benzamides; Catalase; Cells, Cultured; Cyclic GMP; Cyclic GMP-Dependent Protein Kinases; Endothelial Cells; Enzyme Activation; Glutathione Peroxidase; Glutathione Peroxidase GPX1; Hydrogen Peroxide; Imatinib Mesylate; Lung; Male; Mice; Mice, Inbred C57BL; Mice, Knockout; Oxidation-Reduction; Piperazines; Protein Kinase Inhibitors; Proto-Oncogene Proteins c-abl; Pyrimidines; RNA, Messenger; Signal Transduction

We recently reported that administration of atrial natriuretic peptide during the perioperative period has prophylactic effects with respect to not only cardiovascular but also respiratory complications following pulmonary resection. However, its mechanisms are not well understood. The objective of the present study was to investigate the mechanism of the prophylactic effects of atrial natriuretic peptide in an acute lung injury model.. For the evaluation of the early phase of pulmonary inflammation, in vitro and in vivo studies using lipopolysaccharide were used. In the in vitro study, the effects of atrial natriuretic peptide on the induction of E-selectin by lipopolysaccharide in human pulmonary artery endothelial cells were evaluated. In the in vivo study, the effects of atrial natriuretic peptide on lipopolysaccharide-induced inflammatory cell infiltration and cytokine levels including tumor necrosis factor-alpha and interleukin-6 in the bronchoalveolar lavage fluid in the lungs of C57/B6 mice were examined. The number of myeloperoxidase-positive staining cells in the tissue sections of the lung of lipopolysaccharide-administered C57/B6 mice was also evaluated.. Atrial natriuretic peptide significantly attenuated the up-regulation of E-selectin expression induced by lipopolysaccharide in human pulmonary artery endothelial cells. There were significantly lower cell counts and levels of tumor necrosis factor-alpha and interleukin-6 in the bronchoalveolar lavage fluid of atrial natriuretic peptide-treated mice compared to control mice after lipopolysaccharide injection. In addition, there were significantly fewer myeloperoxidase-positive cells in atrial natriuretic peptide-treated mice than in control mice after lipopolysaccharide injection.. Atrial natriuretic peptide had a protective effect in the lipopolysaccharide-induced acute lung injury model. Atrial natriuretic peptide may be of value in therapeutic strategies aimed at the treatment of acute lung injury such as pneumonia or acute respiratory distress syndrome.

Topics: Acute Lung Injury; Animals; Atrial Natriuretic Factor; Bronchoalveolar Lavage Fluid; Disease Models, Animal; E-Selectin; Endothelial Cells; Humans; Interleukin-6; Lipopolysaccharides; Lung; Mice; Mice, Inbred C57BL; Pulmonary Artery; Tumor Necrosis Factor-alpha; Up-Regulation

An inflammatory response leading to organ dysfunction and failure continues to be a major problem after injury in many clinical conditions such as sepsis, severe burns, and trauma. It is increasingly recognized that atrial natriuretic peptide (ANP) possesses a broad range of biological activities, including effects on endothelial function and inflammation. A recent study has revealed that ANP exerts anti-inflammatory effects. In this study we tested the effects of human ANP (hANP) on lung injury in a model of oleic acid (OA)-induced acute lung injury (ALI) in rats.. Rats were randomly assigned to three groups (n = 6 in each group). Rats in the control group received a 0.9% solution of NaCl (1 ml × kg(-1) × h(-1)) by continuous intravenous infusion, after 30 minutes a 0.9% solution of NaCl (1 ml/kg) was injected intravenously, and then the 0.9% NaCl infusion was restarted. Rats in the ALI group received a 0.9% NaCl solution (1 ml × kg(-1) × h(-1)) intravenous infusion, after 30 minutes OA was injected intravenously (0.1 ml/kg), and then the 0.9% NaCl infusion was restarted. Rats in the hANP-treated ALI group received a hANP (0.1 µg × kg(-1) × min(-1)) infusion, after 30 minutes OA was injected intravenously (0.1 ml/kg), and then the hANP infusion was restarted. The anti-inflammation effects of hANP were evaluated by histological examination and determination of serum cytokine levels.. Serum interleukin (IL)-1β, IL-6, IL-10 and tumor necrosis factor (TNF) α were increased in the ALI group at six hours. The levels of all factors were significantly lower in the hANP treated rats (P < 0.005). Similarly, levels of IL-1β, IL-6, IL-10 and TNF-α were higher in the lung tissue in the ALI group at six hours. hANP treatment significantly reduced the levels of these factors in the lungs (P < 0.005). Histological examination revealed marked reduction in interstitial congestion, edema, and inflammation.. hANP can attenuate inflammation in an OA-induced lung injury in rat model.

Topics: Acute Lung Injury; Animals; Atrial Natriuretic Factor; Disease Models, Animal; Inflammation; Male; Oleic Acid; Rats; Rats, Wistar

Plasma atrial natriuretic peptide levels (proANP (1-98)), a parameter of myocardial dysfunction, have been reported to be increased in critically ill patients with acute lung injury/acute respiratory distress syndrome (ALI/ARDS). The aim of the study was to examine if proANP is a biomarker of ALI/ARDS as assessed by the Sequential Organ Failure Assessment score (SOFA Lung ≥2) in burn patients, and how it compares to the corresponding values for age, total body surface area percent (TBSA%) and inhalation injury for mortality prediction.. A group of 22 burn patients with a mean TBSA of 30% (10-75%) and a mean age of 52 years (25-84 years) was investigated during 2010. Organ dysfunction/failure was classified according to the SOFA score. The criteria for ALI/ARDS were based on SOFA Lung ≥2. ProANP (1-98) concentrations (nmoll(-1)) were measured by commercially available enzyme linked immunosorbent assay (ELISA) immunoassays (Biomedica Austria) on post-burn days 2 and 7.. ProANP levels on day 7 post-burn positively correlated with a SOFA score day 7 post-burn, c=0.91. The receiver operating curve (ROC) analysis proved a sensitivity of 75% and a specificity of 75% for ALI/ARDS at cut-off values >3.35 nmoll(-1). The ROC value of proANP for ALI/ARDS (SOFA Lung ≥2) was significantly larger than that of age, TBSA% and inhalation injury: 0.90, 0.71, 0.74, and 0.69 (p<0.001).. ProANP levels, as a biomarker of ALI/ARDS, in critically burn patients correlated with SOFA scoring. The inhalation injury did not lead to increase in proANP values.

Topics: Acute Lung Injury; Adult; Aged; Aged, 80 and over; Atrial Natriuretic Factor; Biomarkers; Burns; Enzyme-Linked Immunosorbent Assay; Female; Humans; Male; Middle Aged; Regression Analysis; Respiratory Distress Syndrome; ROC Curve; Sensitivity and Specificity

Lung inflammation and alterations in endothelial cell (EC) permeability are key events to development of acute lung injury (ALI). Protective effects of atrial natriuretic peptide (ANP) have been shown against inflammatory signaling and endothelial barrier dysfunction induced by gram-negative bacterial wall liposaccharide. We hypothesized that ANP may possess more general protective effects and attenuate lung inflammation and EC barrier dysfunction by suppressing inflammatory cascades and barrier-disruptive mechanisms shared by gram-negative and gram-positive pathogens. C57BL/6J wild-type or ANP knockout mice (Nppa-/-) were treated with gram-positive bacterial cell wall compounds, Staphylococcus aureus-derived peptidoglycan (PepG) and/or lipoteichoic acid (LTA) (intratracheal, 2.5 mg/kg each), with or without ANP (intravenous, 2 μg/kg). In vitro, human pulmonary EC barrier properties were assessed by morphological analysis of gap formation and measurements of transendothelial electrical resistance. LTA and PepG markedly increased pulmonary EC permeability and activated p38 and ERK1/2 MAP kinases, NF-κB, and Rho/Rho kinase signaling. EC barrier dysfunction was further elevated upon combined LTA and PepG treatment, but abolished by ANP pretreatment. In vivo, LTA and PepG-induced accumulation of protein and cells in the bronchoalveolar lavage fluid, tissue neutrophil infiltration, and increased Evans blue extravasation in the lungs was significantly attenuated by intravenous injection of ANP. Accumulation of bronchoalveolar lavage markers of LTA/PepG-induced lung inflammation and barrier dysfunction was further augmented in ANP-/- mice and attenuated by exogenous ANP injection. These results strongly suggest a protective role of ANP in the in vitro and in vivo models of ALI associated with gram-positive infection. Thus ANP may have important implications in therapeutic strategies aimed at the treatment of sepsis and ALI-induced gram-positive bacterial pathogens.

Topics: Acute Lung Injury; Animals; Atrial Natriuretic Factor; Dose-Response Relationship, Drug; Endothelium, Vascular; Humans; In Vitro Techniques; Male; Mice; Mice, Inbred C57BL; Mice, Knockout; Staphylococcal Infections; Treatment Outcome

Acute lung injury, a common component of systemic inflammatory disease, is a life-threatening condition without many effective treatments. However, recent studies have demonstrated that the multifunctional human atrial natriuretic peptide (hANP) exerts anti-inflammatory effects. Therefore, we tested the hypothesis that hANP could prevent lipopolysaccharide (LPS)-induced acute lung injury in a rodent model. Rats received an LPS injection and continuous intravenous infusion (CIV) of hANP or saline solution. We evaluated the anti-inflammatory effects of hANP by histological examination and determination of serum cytokine levels and lung myeloperoxidase (MPO) activity. Histological examination revealed marked reductions in interstitial congestion, edema, inflammation, and hemorrhage in lung tissue harvested 12 h after hANP treatment compared with tissue from rats that received saline treatment after LPS. LPS injection induced elevated cytokine (IL-1beta and IL-6) secretion and lung MPO activity, which was also attenuated by hANP treatment. Taken together, these data demonstrate that hANP exerts an anti-inflammatory effect and may have potential as a therapeutic agent to treat systemic inflammatory diseases.

Topics: Acute Lung Injury; Animals; Atrial Natriuretic Factor; Humans; Infusions, Intravenous; Interleukin-1beta; Interleukin-6; Lipopolysaccharides; Male; Peroxidase; Rats; Rats, Wistar

Topics: Acute Lung Injury; Animals; Atrial Natriuretic Factor; C-Reactive Protein; Disease Models, Animal; Drowning; Female; Male; Malondialdehyde; Nitric Oxide; Rabbits; Random Allocation