Overexpression of HMGB1 A-box reduced lipopolysaccharide-induced intestinal inflammation via HMGB1/TLR4 signaling in vitro

AIM: To investigate the inhibitory effects and mechanism of high mobility group box(HMGB)1 A-box in lipopolysaccharide(LPS)-induced intestinal inflammation.METHODS: Overexpression of HMGB1 A-box in human intestinal epithelial cell lines(SW480 cells) was achieved using the plasmid p EGFP-N1. HMGB1 A-box-overexpressing SW480 cells were stimulated with LPS and co-culturing with human monocyte-like cell lines(THP-1 cells) using a Transwell system, compared with another HMGB1 inhibitor ethyl pyruvate(EP). The m RNA and protein levels of HMGB1/toll-like receptor(TLR) 4 signaling pathways [including HMGB1, TLR4, myeloid differentiation factor88(MYD88), Phosphorylated Nuclear Factor κB(p NF-κB) p65] in the stimulated cells were determined by realtime polymerase chain reaction and Western blotting. The levels of the proinflammatory mediators [including HMGB1, interleukin(IL)-1β, IL-6 and tumor necrosis factor(TNF)-α] in the supernatants of the stimulated cells were determined by ELISA.RESULTS: EP downregulated the m RNA and protein levels of HMGB1, inhibited the TLR4 signaling pathways(TLR4, MYD88 and p NF-κB p65) and reduced the secretion of proinflammatory mediators(HMGB1, IL-1β, IL-6 and TNF-α) in the SW480 and THP-1 cells activated by LPS but not in the unstimulated cells. Activated by LPS, the overexpression of HMGB1 A-box in the SW480 cells also inhibited the HMGB1/TLR4 signaling pathways and reduced the secretion of these proinflammatory mediators in the THP-1 cells but not in the transfected and unstimulated cells. CONCLUSION: HMGB1 A-box, not only EP, can reduce LPS-induced intestinal inflammation through inhibition of the HMGB1/TLR4 signaling pathways.