Mesenchymal Stem Cells Attenuate Sepsis-associated Acute Kidney Injury by Changing the Balance of Th17 cells/Tregs via Gal-9/Tim-3.

ABSTRACT

OBJECTIVE: The aim of the present study was to investigate the protective effect of MSCs on CLP-induced SA-AKI and determine the mechanisms of this effect. METHODS: The expression of Gal-9 and Tim-3 was assayed by qPCR and western blot. IL-10, IL-17, RORγt, and FOXP3 were assayed by qPCR and TNFα, INFγ, IL-4, and IL-6 were assayed by ELISA in renal samples after CLP with or without MSCs treatment. The expression of Gal-9 in MSCs was knocked down in vivo using RNA interference, and si-Gal-9-MSCs were injected in SA-AKI mice. The effect of MSCs on the differentiation of lymphocytes into Th17 cells and Tregs was evaluated in vitro by FAC in coculture of MSCs and CD4+ T cells and after blockade of the Gal-9/Tim-3 pathway. RESULTS: MSCs decreased serum creatinine and urea nitrogen levels and relieved tubular injury. Additionally, MSCs significantly improved the survival rate and markedly attenuated the infiltration of neutrophils and the levels of TNF-α, IFN-γ, IL-4, and IL-6 in the kidneys of septic mice (P < 0.05). Treatment with MSCs also reduced the proportion of Th17 cells and the levels of IL-17 and RORγt (P < 0.05). In contrast, MSCs increased the proportion of Tregs and the levels of IL-10 and FOXP3 related to these cells (P < 0.05). Furthermore, we determined whether Gal-9/Tim-3 and Th17 cells/Tregs are involved in the protective effects of MSCs in an SA-AKI model. The results of Western blot and real-time PCR indicated that MSCs inhibited the expression of Tim-3 and increased the expression of gal-9 (P < 0.05). Knockdown of gal-9 in MSCs using small interfering RNA blunted the therapeutic effect of MSCs, and blockade of the Gal-9/Tim-3 pathway using α-lactose or anti-Tim-3 inhibited the induction of Tregs and suppressed the inhibition of the differentiation to Th17 cells by MSCs after coculture of MSCs with CD4+ T cells (P > 0.05). CONCLUSION: Treatment with MSCs can protect against SA-AKI. The results suggested that the relieving effect of MSCs against SA-AKI may be partially mediated by the induction of Tregs and inhibition of Th17 cells via the Gal-9/Tim-3 pathway.