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Abstract. Acute kidney injury (AKI) is a severe complication of sepsis with a high mortality and morbidity. Pterostilbene (Pte) has been suggested to confer anti-apoptotic and anti-inflammatory effects. In the current study, the effects of Pte on AKI were evaluated in septic mice. Cecal ligation and puncture surgery was performed to induce sepsis. The results suggested that Pte administration significantly decreased the levels of serum urea nitrogen and creatinine, and improved the survival rate of septic mice. Additionally, the renal injury induced by sepsis was attenuated by pterostilbene treatment. Notably, pterostilbene reduced Bcl-2-associated X protein expression, and levels of interleukin-1β and tumor necrosis factor-α, and upregulated B-cell lymphoma 2 expression. The results indicate that pterostilbene may serve as a potential therapeutic candidate for the treatment of AKI induced by sepsis.

High mobility group box 1 protein (HMGB1), a critical proinflammatory cytokine, has recently been identified to be an immunostimulatory signal involved in sepsis-related immune dysfunction when released extracellularly, but the potential mechanism involved remains elusive. Here, we showed that the treatment with HMGB1 in vitro inhibited T lymphocyte immune response and expression of mitofusin-2 (Mfn-2; a member of the mitofusin family) in a dose-and time-dependent manner. Upregulation of Mfn-2 expression attenuated the suppressive effect of HMGB1 on T cell immune function. The phosphorylation of both extracellular signal-regulated kinase (ERK)1/2 and p38 mitogen-activated protein kinase (MAPK) was markedly upregulated by treating with high amount of HMGB1, while pretreatment with ERK1/2 and p38 MAPK-specific inhibitors (U0126 and SB203580) could attenuate suppression of T cell immune function and nuclear factor of activated T cell (NFAT) activation induced by HMGB1, respectively. HMGB1-induced activity of ERK1/2 and p38 was not fully inhibited in the presence of U0126 or SB203580. Interestingly, overexpression of Mfn-2 had no marked effect on HMGB1-mediated activation of MAPK, but could attenuate the suppressive effect of HMGB1 on the activity of NFAT. Thus, the mechanisms involved in HMGB1-induced T cell immune dysfunction in vitro at least partly include suppression of Mfn-2 expression, overactivation of ERK1/2, p38 MAPK, and intervention of NFAT activation, while the protective effect of Mfn-2 on T cell immune dysfunction induced by HMGB1 is dependent on other signaling pathway associated with NFAT, but not MAPK. Taken together, we conclude that overactivation of MAPK and suppression of Mfn-2 expression are two independent events in HMGB1-mediated T cell immune dysfunction.