[Expression of high-mobility group box 1 in neonates with sepsis].

OBJECTIVE: To study the expression of high-mobility group box 1 (HMGB1) in neonates with sepsis and its role in the pathogenesis of neonatal sepsis. METHODS: A total of 62 neonates with sepsis were enrolled as the sepsis group, 66 neonates with local infection were enrolled as the local infection group, and 70 healthy neonates were enrolled as the healthy control group. Serum levels of interleukin-6 (IL-6), interleukin-8 (IL-8), interleukin-17 (IL-17), interleukin-23 (IL-23), C-reactive protein (CRP) and procalcitonin (PCT) were measured. The mRNA expression of HMGB1, Toll-like receptor 4 (TLR4) and nuclear factor-kappa B (NF-κB) and the protein expression of TLR4 and NF-κB in peripheral blood mononuclear cells (PBMCs) were also measured. PBMCs from healthy neonates were divided into 4 groups: control, HMGB1 treatment, HMGB1+TAK-242 (a TLR4 inhibitor) treatment and HMGB1+PDTC (an NF-κB inhibitor) treatment, and the mRNA expression of TLR4, NF-κB and IL-8 and the protein expression of TLR4 and NF-κB were measured. PBMCs from healthy neonates were divided into another 3 groups: control, LPS treatment and LPS+glycyrrhizin (an HMGB1 inhibitor) treatment, and the mRNA expression of HMGB1, TLR4, NF-κB and IL-8 and the protein expression of TLR4 and NF-κB were measured. RESULTS: Compared with the local infection and healthy control groups, the sepsis group had significantly higher serum levels of IL-6, IL-8, IL-17, IL-23, CRP and PCT (P<0.05), as well as significantly higher mRNA expression of HMGB1, TLR4 and NF-κB and protein expression of TLR4 and NF-κB in PBMCs (P<0.05). HMGB1 significantly induced the mRNA and protein expression of TLR4 and NF-κB in PBMCs (P<0.05). TAK-242 inhibited the mRNA and protein expression of TLR4 and NF-κB and mRNA expression of IL-8 (P<0.05). PDTC inhibited the mRNA and protein expression of NF-κB and the mRNA expression of IL-8 (P<0.05). LPS significantly induced the mRNA expression of HMGB1 and the mRNA and protein expression of TLR4 and NF-κB and then stimulated the mRNA expression of IL-8 (P<0.05). Glycyrrhizin inhibited the mRNA expression of HMGB1 and the mRNA and protein expression of TLR4 and NF-κB and then reduced the mRNA expression of IL-8 (P<0.05). CONCLUSIONS: HMGB1 plays an important role in the pathogenesis of neonatal sepsis by activating the TLR4/NF-κB signaling pathway and inducing the secretion of inflammatory factors including IL-8. The HMGB1 blocker glycyrrhizin can inhibit activation of the TLR4/NF-κB signaling pathway and the secretion of inflammatory factors.