calpain-inhibitor-iii and Sepsis

Recent studies in septic models have shown that myocardial calpain activity and TNF-α expression increase during sepsis and that inhibition of calpain activation downregulates myocardial TNF-α expression and improves cardiac dysfunction. However, the mechanism underlying this pathological process is unclear. Thus, in the present study, we aimed to explore whether IκBα/NF-κB signaling linked myocardial calpain activity and TNF-α expression in septic mice. Adult male mice were injected with LPS (4 mg/kg ip) to induce sepsis. Myocardial calpain activity, IκBα/NF-κB signaling activity, and TNF-α expression were assessed, and myocardial function was evaluated using the Langendorff system. In septic mice, myocardial calpain activity and TNF-α expression were increased and IκBα protein was degraded. Furthermore, NF-κB was activated, as indicated by increased NF-κB p65 phosphorylation, cleavage of p105 into p50, and its nuclear translocation. Administration of the calpain inhibitors calpain inhibitor Ш and PD-150606 prevented the LPS-induced degradation of myocardial IκBα, NF-κB activation, and TNF-α expression and ultimately improved myocardial function. In calpastatin transgenic mice, an endogenous calpain inhibitor and cultured neonatal mouse cardiomyocytes overexpressing calpastatin also inhibited calpain activity, IκBα protein degradation, and NF-κB activation after LPS treatment. In conclusion, myocardial calpain activity was increased in septic mice. Calpain induced myocardial NF-κB activation, TNF-α expression, and myocardial dysfunction in septic mice through IκBα protein cleavage.

Topics: Acrylates; Animals; Calcium-Binding Proteins; Calpain; Dipeptides; Disease Models, Animal; Heart; Heart Diseases; I-kappa B Proteins; Lipopolysaccharides; Male; Mice; Mice, Inbred C57BL; Myocardium; NF-kappa B; NF-KappaB Inhibitor alpha; Sepsis; Signal Transduction; Tumor Necrosis Factor-alpha

Recent studies have demonstrated that myocardial calpain triggers caspase-3 activation and myocardial apoptosis in models of sepsis, whereas the inhibition of calpain activity down-regulates myocardial caspase-3 activation and apoptosis. However, the mechanism underlying this pathological process is unclear. Therefore, in this study, our aim was to explore whether the Hsp90/Akt signaling pathway plays a role in the induction of myocardial calpain activity, caspase-3 activation and apoptosis in the septic mice.. Adult male C57 mice were injected with lipopolysaccharide (LPS, 4 mg/kg, i.p.) to induce sepsis. Next, myocardial caspase-3 activity and the levels of Hsp90/p-Akt (phospho-Akt) proteins were detected, and apoptotic cells were assessed by performing the TUNEL assay.. In the septic mice, there was an increase in myocardial calpain and caspase-3 activity in addition to an increase in the number of apoptotic cells; however, there was a time-dependent decrease in myocardial Hsp90/p-Akt protein levels. The administration of calpain inhibitors (calpain inhibitor-Ш or PD150606) prevented the LPS-induced degradation of myocardial Hsp90/p-Akt protein and its expression in cardiomyocytes in addition to inhibiting myocardial caspase-3 activation and apoptosis. The inhibition of Hsp90 by pretreatment with 17-AAG induced p-Akt degradation, and the inhibition of Akt activity by pretreatment with wortmannin resulted in caspase-3 activation in wildtype C57 murine heart tissues.. Myocardial calpain induces myocardial caspase-3 activation and apoptosis in septic mice via the activation of the Hsp90/Akt pathway.

Topics: Acrylates; Androstadienes; Animals; Apoptosis; Benzoquinones; Calpain; Caspase 3; Cysteine Proteinase Inhibitors; Dipeptides; Disease Models, Animal; Enzyme Activation; HSP90 Heat-Shock Proteins; In Situ Nick-End Labeling; Lactams, Macrocyclic; Lipopolysaccharides; Male; Mice; Mice, Inbred C57BL; Myocardium; Phosphatidylinositol 3-Kinase; Phosphoinositide-3 Kinase Inhibitors; Phosphorylation; Protein Kinase Inhibitors; Proto-Oncogene Proteins c-akt; Sepsis; Signal Transduction; Time Factors; Wortmannin