Interleukin-10 Contributes to Therapeutic Effect of Mesenchymal Stem Cells for Acute Liver Failure via Signal Transducer and Activator of Transcription 3 Signaling Pathway

Background：Mesenchymal stem cells （MSCs） transplantation has been proven to have therapeutic potential for acute liver failure （ALF）.However,the mechanism remains controversial.Recently,modulation of inflammation by MSCs has been regarded as a crucial mechanism.The aim of the present study was to explore the soluble cytokines secreted by MSCs and their therapeutic effects in ALF.Methods：MSCs isolated from Sprague-Dawley rats were identified by fluorescence-activated cell sorting analysis.Conditioned medium derived from MSCs （MSCs-CM） was collected and analyzed by a cytokine microarray.MSCs and MSCs-CM were transplanted into rats with D-galactosamine-induced ALF.Liver function,survival rate,histology,and inflammatory factors were determined.Exogenous recombinant rat interleukin （IL）-10,anti-rat IL-10 antibody,and AG490 （signal transducer and activator of transcription 3 [STAT3] signaling pathway inhibitor） were administered to explore the therapeutic mechanism of MSCs-CM.Statistical analysis was performed with SPSS version 19.0,and all data were analyzed by the independent-sample t-test.Results：There are statistical differences of the survival curve between ALF＋MSCs group and ALF＋Dulbecco＆#39;s modified Eagle＆#39;s medium （DMEM） group,as well as ALF＋MSCs-CM group and ALF＋DMEM group （all P 〈 0.05）.Serum alanine aminotransferase （ALT） level in the ALF＋MSCs and ALF＋MSCs-CM groups was lower than that in the ALF＋DMEM group （865.53＆#177;52.80 vs.1709.75＆#177;372.12 U/L and 964.72＆#177;414.59 vs.1709.75＆#177;372.12 U/L,respectively,all P 〈 0.05）;meanwhile,serum aspartate aminotransferase （AST） level in the ALF＋MSCs and ALF＋MSCs-CM groups was lower than that in the ALF＋DMEM group （2440.83＆#177;511.94 vs.4234.35＆#177;807.30 U/L and 2739.83＆#177;587.33 vs.4234.35＆#177;807.30 U/L,respectively,all P 〈 0.05）.Furthermore,MSCs or MSCs-CM treatment significantly reduced serum interferon-γ （IFN-γ）,IL-1β,IL-6 levels and increased serum IL-10 level compared with DMEM （all P 〈 0.05）.Proteome profile analysis of MSCs-CM indicated the presence of anti-inflammatory factors and IL-l 0 was the most distinct.Blocking of IL-10 confirmed the therapeutic significance of this cytokine.Phosphorylated STAT3 was upregulated after IL-l 0 infusion and inhibition of STAT3 by AG490 reversed the therapeutic effect of IL-10.Conclusions：The factors released by MSCs,especially IL-10,have the potential for therapeutic recovery of ALF,and the STAT3 signaling pathway may mediate the anti-inflammatory