Inhibition of LPS-induced inflammation manifestations in vivo and in vitro by recombinant HSC70 preconditioning

JL Yeh1, JH Hsu2,3, JR Wu2,3, RC Yang2,3, LC Wu1, SJ Lin1. 1College of Medicine, Kaohsiung Medical University, Department of Pharmacology, Taiwan, 2College of Medicine, Kaohsiung Medical University, Department of Pediatrics, Taiwan, 3Kaohsiung Medical University Hospital, Department of Pediatrics, Taiwan

Recent studies suggest that heat shock cognate protein 70 (HSC70), a previously recognized intracellular chaperone protein, can also be released to extracellular space and can protect myocardium from ischemia-reperfusion injury. In this study, we hypothesized that recombinant HSC70 is able to protect animals and cells from lipopolysaccharide (LPS)-induced myocardial dysfunction and associated inflammatory responses.

In a rat model of LPS-induced sepsis, we demonstrated that pretreatment of male Wistar rats weighing 250-350 g with HSC70 (20 μg/kg, iv; n = 6) significantly attenuated left ventricular myocardial depression, and hypotension caused by LPS, with associated improvement of biochemical parameters including GOT/GPT, LDH and glucose (p < 0.05). In addition, HSC70 inhibited the elevation of plasma TNF-α and nitric oxide (NO), it also decreased the myocardial levels of iNOS and COX-2 in response to LPS challenge. The data were analyzed by ANOVA followed by Dunnett’s test.

To further investigate the mechanisms of these protective effects of HSC70, neonatal rat cardiomyocytes were studies and we found that preconditioning of neonatal Wistar rat cardiomyocytes with HSC70 (0.1, 1 and 5 μg/ml) reduced LPS-induced cardiomyocytes hypertrophy dose-dependently. Similarly, HSC70 preconditioning also exhibited inhibitory effects on iNOS, COX-2, TNF-α, IL-6 and NO production in LPS-induced cardiomyocytes. Furthermore, we found that HSC70 preconditioning repressed the activation of mitogen-activated protein kinases (MAPKs) caused by LPS. In parallel, HSC70 preconditioning reduced LPS-induced nuclear translocation of nuclear factor-κB (NF-κB) subunit p65 by blocking phosphorylation of Akt and inhibitor κB (IκB)α as well as the degradation of IκBα (p < 0.05).

Taken together, our results show that extracellular HSC70 have dual protective effects of inflammatory modulation and myocardial protection in sepsis both in vivo and in vitro. Therefore, extracellular HSC70 may have a promising role in pharmacologic strategy in the treatment of sepsis.