Role of interlukin-6 and signal transducer and activator of transcription 3 signaling pathway in up-regulation of high mobility group box 1 expression in lung tissues in septic rats

Objective To evaluate the role of interlukin-6 and signal transducer and activator of transcription 3 (IL-6/STAT3) signaling pathway in the up-regulation of high mobility group box 1 (HMGB1) expression in lung tissues in septic rats.Methods Ninety healthy male Wistar rats,aged 10-14 weeks,weighing 250-300 g,were randomly divided into 3 groups (n =30 each):sham operation group (group S),cecal ligation and puncture (CLP) group and anti-IL-6 monoclonal antibody group (group IL-6).Sepsis was induced by CLP.Anti-IL-6 monoclonal antibody 0.5 mg/kg was injected intraperitoneally 1 h before CLP,while the equal volume of normal saline was given in groups S and CLP.Six rats in each group were sacrificed at 6,12,24,48 and 72 h after CLP and lungs were removed for determination of HMGB1 content (by RT-PCR),HMGB1 mRNA expression (by ELISA) and STAT3-DNA binding activity (by electrophoretic mobility shift assay) in lung tissues.Results Compared with S group,HMGB1 content,HMGB1 mRNA expression and STAT3-DNA binding activity were significantly increased in groups CLP and IL-6 (P ＜ 0.05).HMGB1 content,HMGB1 mRNA expression and STAT3-DNA binding activity were significantly lower in group IL-6 than in group CLP (P ＜ 0.05).Conclusion IL-6/STAT3 signaling pathway is involved in the up-regulation of HMGB1 expression in lung tissues in septic rats. Key words: Interleukin-6;  STAT3 transcription factor;  Lung;  Sepsis;  High mobility group proteins