calpain and Endotoxemia

Liver failure after hepatectomy is caused by many factors such as excessive hepatectomy, ischemic-reperfusion injury, postoperative infection, etc. However, apoptosis of hepatocytes is the most important event in the molecular mechanism of liver failure. Liver failure after excessive hepatectomy is characterized by increased apoptosis of hepatocytes and diminished liver regeneration. The former is induced by hypercytokinemia and hyperendotoxemia, and the latter is caused by cell cycle arrest. In ischemic-reperfusion injury of the liver, the apoptosis of hepatocytes is caused by activation of the MMPT and calpain system that are induced by the intracellular accumulation of Ca. The possible mechanism of liver failure in cases with persistent infection is the inhibition of liver regeneration and the induction of apoptosis of hepatocytes due to transforming growth factor-beta 1. The knowledge of these mechanisms will lead to prompt and appropriate treatments for individual patients.

Topics: Animals; Apoptosis; Calcium; Calpain; Cell Membrane Permeability; Cytokines; Endotoxemia; Hepatectomy; Hepatocytes; Humans; Liver Failure; Mitochondria; Postoperative Complications; Reperfusion Injury; Transforming Growth Factor beta; Transforming Growth Factor beta1

Sepsis-induced cardiomyopathy contributes to the high mortality of septic shock in critically ill patients. Since the underlying mechanisms are incompletely understood, we hypothesized that sepsis-induced impairment of sirtuin 3 (SIRT3) activity contributes to the development of septic cardiomyopathy.. Treatment of mice with lipopolysaccharide (LPS) for 6 h resulted in myocardial NAD. Impaired SIRT3 activity may mediate cardiac dysfunction in endotoxemia by facilitating calpain-mediated disruption of ATP synthesis, suggesting SIRT3 activation as a potential therapeutic strategy to treat septic cardiomyopathy.

Topics: Adenosine Triphosphate; Animals; Calpain; Cytokines; Disease Models, Animal; Endotoxemia; Enzyme Activation; Heart Diseases; Humans; Male; Mice; Mice, Knockout; Mitochondria, Heart; Myocytes, Cardiac; Oxidative Stress; Sepsis; Signal Transduction; Sirtuin 3

Our recent study has demonstrated that inhibition of calpain by transgenic overexpression of calpastatin reduces myocardial proinflammatory response and dysfunction in endotoxemia. However, the underlying mechanisms remain to be determined. In this study, we used cardiomyocyte-specific capn4 knockout mice to investigate whether and how calpain disrupts ATP synthase and induces mitochondrial superoxide generation during endotoxemia.. Cardiomyocyte-specific capn4 knockout mice and their wild-type littermates were injected with lipopolysaccharides. Four hours later, calpain-1 protein and activity were increased in mitochondria of endotoxemic mouse hearts. Mitochondrial calpain-1 colocalized with and cleaved ATP synthase-α (ATP5A1), leading to ATP synthase disruption and a concomitant increase in mitochondrial reactive oxygen species generation during lipopolysaccharide stimulation. Deletion of capn4 or upregulation of ATP5A1 increased ATP synthase activity, prevented mitochondrial reactive oxygen species generation, and reduced proinflammatory response and myocardial dysfunction in endotoxemic mice. In cultured cardiomyocytes, lipopolysaccharide induced mitochondrial superoxide generation that was prevented by overexpression of mitochondria-targeted calpastatin or ATP5A1. Upregulation of calpain-1 specifically in mitochondria sufficiently induced superoxide generation and proinflammatory response, both of which were attenuated by ATP5A1 overexpression or mitochondria-targeted superoxide dismutase mimetics.. Cardiomyocyte-specific capn4 knockout protects the heart against lipopolysaccharide-induced injury in endotoxemic mice. Lipopolysaccharides induce calpain-1 accumulation in mitochondria. Mitochondrial calpain-1 disrupts ATP synthase, leading to mitochondrial reactive oxygen species generation, which promotes proinflammatory response and myocardial dysfunction during endotoxemia. These findings uncover a novel mechanism by which calpain mediates myocardial dysfunction in sepsis.

Topics: Animals; Calpain; Disease Models, Animal; DNA; Endotoxemia; Female; Gene Deletion; Gene Expression Regulation; Male; Mice; Mice, Inbred C57BL; Mice, Transgenic; Mitochondria, Heart; Mitochondrial Proton-Translocating ATPases; Myocardial Reperfusion Injury; Myocardium; Myocytes, Cardiac; Oxidative Phosphorylation Coupling Factors

Lipopolysaccharide (LPS) induces cardiomyocyte caspase-3 activation and proinflammatory factors, in particular tumour necrosis factor-alpha (TNF-alpha) production, both of which contribute to myocardial dysfunction during sepsis. The present study was to investigate the roles of calpain/calpastatin system in cardiomyocyte caspase-3 activation, TNF-alpha expression, and myocardial dysfunction during LPS stimulation.. In cultured adult rat cardiomyocytes, LPS (1 microg/mL) induced calpain and caspase-3 activity, and up-regulated TNF-alpha expression. These effects of LPS were abrogated by over-expression of calpastatin, an endogenous calpain inhibitor, transfection of calpain-1 siRNA, or various pharmacological calpain inhibitors. Furthermore, blocking gp91(phox)-NADPH oxidase prevented calpain and caspase-3 activation and decreased TNF-alpha expression in LPS-stimulated cardiomyocytes. To investigate the role of calpastatin in endotoxaemia, transgenic mice with calpastatin over-expression (CAST-Tg) and wild-type mice were treated with LPS (4 mg/kg, i.p.) or saline in the presence of calpain inhibitor-III (10 mg/kg, i.p.) for 4 h, and their heart function was measured with a Langendorff system. Over-expression of calpastatin significantly attenuated myocardial dysfunction (P < 0.05). Consistently, calpain activity, caspase-3 activity, and TNF-alpha expression were also reduced in CAST-Tg and calpain inhibitor-III compared with wild-type and vehicle-treated hearts, respectively.. gp91(phox)-NADPH oxidase-mediated calpain-1 activation induces caspase-3 activation and TNF-alpha expression in cardiomyocytes during LPS stimulation. Over-expression of calpastatin inhibits calpain activation and improves myocardial function in endotoxaemia. The present study suggests that targeting calpain/calpastatin system may be a potential therapeutic intervention for septic hearts.

Topics: Acrylates; Animals; Calcium-Binding Proteins; Calpain; Caspase 3; Cells, Cultured; Cysteine Proteinase Inhibitors; Dipeptides; Disease Models, Animal; Endotoxemia; Heart; Lipopolysaccharides; Male; Membrane Glycoproteins; Mice; Mice, Inbred C57BL; Mice, Transgenic; Myocardium; Myocytes, Cardiac; NADPH Oxidase 2; NADPH Oxidases; Rats; Rats, Sprague-Dawley; RNA, Small Interfering; Tumor Necrosis Factor-alpha

Systemic exposure to bacterial lipopolysaccharide (LPS, endotoxin) induces hypotension, disseminated intravascular coagulation and neutrophil infiltration in various organs including the lung, kidney and liver. A rat endotoxemic neutrophilic hepatitis model (repeat dose LPS, 10 mg/kg, i.v. 24 hours apart) was developed exhibiting hepatic neutrophil infiltration and mid-zonal hepatic necrosis. The goal of the study was to investigate the role of the intracellular enzyme calpain in the development of neutrophilic hepatitis with midzonal necrosis in this model. A second goal was to compare the observed protective effects of calpain inhibition with a relatively selective inducible nitric oxide synthase (iNOS) inhibitor aminoguanidine (AG) and an inhibitor of coagulation, heparin. When compared to rats administered LPS alone, administration of calpain 1 inhibitor prior to LPS significantly reduced hepatic iNOS expression, hepatic neutrophil infiltration and attenuated midzonal hepatic necrosis. Administration of AG or heparin prior to LPS also decreased liver iNOS expression, hepatic neutrophil infiltration and liver pathology comparable to calpain inhibition. Blood neutrophil activation, as measured by the neutrophil adhesion molecule CD11b integrin, was upregulated in all the LPS treated groups regardless of inhibitor administration. We conclude that amelioration of liver pathology via calpain inhibition is likely dependent on the down-regulation of iNOS expression in the rat model of LPS-mediated hepatitis.

Topics: Animals; Anticoagulants; Blood Coagulation; Blotting, Western; Calpain; Carrier Proteins; Chemical and Drug Induced Liver Injury; Cysteine Proteinase Inhibitors; Cytochrome P-450 CYP2E1; Disease Models, Animal; Endotoxemia; Endotoxins; Enzyme Inhibitors; Flow Cytometry; Glycoproteins; Guanidines; Heparin; Liver; Male; Microfilament Proteins; Necrosis; Neutrophil Activation; Neutrophils; Nitric Oxide Synthase Type II; Rats; Rats, Sprague-Dawley

Caspase-1-deficient (-/-) mice are protected against sepsis-induced hypotension and mortality. We investigated the role of caspase-1 and its associated cytokines in a nonhypotensive model of endotoxemic acute renal failure (ARF). Mice were injected intraperitoneally with 2.5 mg of LPS that induces endotoxemic ARF. On immunoblot analysis of whole kidney, there was an increase in caspase-1 protein in LPS-treated mice compared with vehicle-treated controls. In LPS-treated mice, the glomerular filtration rate (GFR) was significantly higher in caspase-1 -/- vs. wild-type mice at 16 and 36 h after LPS. To determine the mechanism of this protection, the caspase-1-activated cytokines IL-1beta and IL-18 were investigated. IL-1beta and IL-18 protein were significantly increased in the kidneys of LPS- vs. vehicle-treated mice. To determine the role of these cytokines, mice were treated with recombinant IL-1 receptor antagonist (IL-1Ra) or IL-18-neutralizing antiserum. In LPS-treated mice, GFR was not different in IL-1Ra-treated or IL-18-neutralizing antiserum-treated or combination therapy (IL-1Ra plus IL-18-neutralizing antiserum-treated) compared with control mice. In addition, tubular cell apoptosis, neutrophil infiltration, myeloperoxidase activity, caspase-3 activity, and calpain activity were not different between wild-type and caspase-1 -/- mice with endotoxemic ARF. In LPS- vs. vehicle-treated wild-type mice, renal IL-1alpha was significantly increased. In both LPS- and vehicle-treated caspase-1 -/- mice, renal IL-1alpha was very low. In summary, caspase-1 -/- mice are functionally protected against endotoxemic ARF. Neutralization of IL-1beta and IL-18 is not functionally protective. The role of the intracellular proinflammatory cytokine IL-1alpha in endotoxemic ARF merits further study.

Topics: Acute Kidney Injury; Animals; Antibodies; Calpain; Caspase 1; Caspase 3; Caspases; Endotoxemia; Glomerular Filtration Rate; Interleukin 1 Receptor Antagonist Protein; Interleukin-1; Interleukin-18; Kidney; Male; Mice; Mice, Inbred C57BL; Mice, Mutant Strains; Peroxidase; Sialoglycoproteins

1. We compared the effects of calpain inhibitor I (inhibitor of the proteolysis of I kappa B and, hence, of the activation of nuclear factor kappa B (NF kappa B) and dexamethasone on (i) the circulatory failure, (ii) multiple organ dysfunction and (iii) induction of the inducible isoforms of nitric oxide (NO) synthase (iNOS) and cyclo-oxygenase (COX-2) in anaesthetized rats with endotoxic shock. 2. Injection of lipopolysaccharide (LPS, E. coli, 10 mg kg-1, i.v.) resulted in hypotension and a reduction of the pressor responses elicited by noradrenaline. This circulatory dysfunction was attenuated by pretreatment of LPS-rats with calpain inhibitor I (10 mg kg-1, i.v., 2 h before LPS) or dexamethasone (1 mg kg-1, i.v.). 3. Endotoxaemia also caused rises in the serum levels of (i) urea and creatinine (renal dysfunction), (ii) alanine aminotransferase (ALT), aspartate aminotransferase (AST) (hepatocellular injury), bilirubin and gamma-glutamyl transferase (gamma GT) (liver dysfunction), (iii) lipase (pancreatic injury) and (iv) lactate. Calpain inhibitor I and dexamethasone attenuated the liver injury, the pancreatic injury, the lactic acidosis as well as the hypoglycaemia caused by LPS. Dexamethasone, but not calpain inhibitor I, reduced the renal dysfunction caused by LPS. 4. Endotoxaemia for 6 h resulted in a substantial increase in iNOS and COX-2 protein and activity in lung and liver, which was attenuated in LPS-rats pretreated with calpain inhibitor I or dexamethasone. 5. Thus, calpain inhibitor I and dexamethasone attenuate (i) the circulatory failure, (ii) the multiple organ dysfunction (liver and pancreatic dysfunction/injury, lactic acidosis, hypoglycaemia), as well as (iii) the induction of iNOS and COX-2 protein and activity in rats with endotoxic shock. We propose that prevention of the activation of NF-kappa B in vivo may be useful in the therapy of circulatory shock or of disorders associated with local or systemic inflammation.

Topics: 6-Ketoprostaglandin F1 alpha; Animals; Calpain; Cysteine Proteinase Inhibitors; Dexamethasone; DNA-Binding Proteins; Endotoxemia; I-kappa B Proteins; Lipopolysaccharides; Male; Mice; Multiple Organ Failure; Nitric Oxide Synthase; Proto-Oncogene Proteins; Rats; Rats, Wistar; Shock, Septic; Tosylphenylalanyl Chloromethyl Ketone; Tumor Necrosis Factor-alpha