Calpain Inhibitors Improve Myocardial Dysfunction and Inflammation Induced by Endotoxin in Rats

Abstract

Excessive activation of calpains has been implicated in the pathophysiology of inflammation, trauma, and ischemia reperfusion injury. Here, we investigated the effects of calpain inhibition on myocardial dysfunction and inflammation induced by endotoxin in rats. Rats were treated i.v. with endotoxin (10 mg/kg) or endotoxin plus calpain inhibitors and were then prepared after 4 h for myocardial contractility assessment, detection of endothelium leukocyte interactions, and plasma TNF-alpha, nitrite/nitrate, and endocan levels. Compared with vehicle-treated rats, hearts from endotoxin-treated rats had reduced systolic performance that was partially prevented by calpain inhibitors, i.e., acetyl-leucyl-leucyl-arginal (leupeptin), carbobenzoxy-valyl-phenylalanial (calpain inhibitor III), and N-acetyl-leucinyl-leucinyl-norleucinal (ALLN). Leupeptin and calpain inhibitor III reduced plasma TNF-alpha levels in endotoxin-treated rats. ALLN reduced plasma TNF-alpha and nitrite/nitrate levels in endotoxin-treated rats. Endotoxin treatment increased mesenteric venule leukocyte rolling (10 +/- 3 leukocytes/min vs. 44 +/- 10 leukocytes/min; P < 0.01) and adhesion (2 +/- 2 leukocytes/min vs. 15 +/- 3 leukocytes/min; P < 0.01), which was reduced by calpain inhibitors. Attenuation of leukocyte endothelium interactions observed in calpain inhibitor-treated rats with sepsis was associated with increases in plasma anti-adhesion molecule endocan. In conclusion, calpain inhibitors improved endotoxin-induced cardiac dysfunction, which may be attributed to the modulation of endothelium leukocyte interactions in the inflamed vasculature.

Cleavage of IκBα by calpain induces myocardial NF-κB activation, TNF-α expression, and cardiac dysfunction in septic mice

“…As we and others have previously reported (15,32,36), myocardial function, as represented by the maximal positive and minimal negative first derivatives of left ventricular pressure, was decreased in septic mice. The administration of calpain inhibitor III or PD-150606 markedly improved the myocardial dysfunction in septic mice (Fig.…”

“…The ability of calpains to cleave cytoskeletal and myofilament proteins in vitro suggests a regulatory role for calpains in heart functions (19,24). Previous reports (15,32,36) have indicated that calpain activation is involved the process of myocardial dysfunction in sepsis. However, the molecular and cellular mechanisms that mediate the pathogenesis of calpaininduced myocardial dysfunction are still not fully understood.…”

“…Fourteen members of the calpain family have been identified to date (2). An association between calpain and myocardial dysfunction during sepsis has been reported; calpain inhibitors attenuated the circulatory failure caused by endotoxins (32) and prevented lipopolysaccharide (LPS)-induced myocardial dysfunction in rats (36). We (15) recently observed that myocardial calpain activity and TNF-␣ mRNA expression increased in septic mice and that inhibition of calpain activation downregulated myocardial TNF-␣ mRNA expression and improved cardiac dysfunction.…”

Endotoxin-induced gene expression differences in the brain and effects of iNOS inhibition and norepinephrine

“…Esm1 is a novel endothelial cell dysfunction marker. Septic rats showed an elevated Esm1 plasma level 4 h after LPS administration [37]. In septic patients the Esm1 blood level is related to the severity of illness and the outcome of the patient [38].…”

Ca2+ and calpain control membrane expansion during rapid cell spreading of neutrophils

“…Neutrophils, however, mainly express calpain-1 and do not form focal adhesion complexes, and there are two reports that calpain inhibitors increase neutrophil motility (Lokuta et al, 2003;Katsube et al, 2008). Although it is not clear whether this latter effect was a result of decreased cell adhesion, there is a significant body of evidence showing that calpain inhibitors are effective in preventing neutrophil extravasation during experimental inflammation in animal models (Noble et al, 1998;Ikeda et al, 2002;Tissier et al, 2004;Cuzzocrea et al, 2000;Marzocco et al, 2004;Yoshifuji et al, 2005) and that calpain inhibition prevents full extension of pseudopodia during phagocytosis by neutrophils (Dewitt and Hallett, 2002) and spreading by lymphocytes (Stewart et al, 1998) and platelets (Croce et al, 1999). In our studies, calpain-inhibited cells were essentially quiescent, or sluggish even after IP 3 uncaging (e.g.…”