Immunological effect of high mobility group box-1 protein on regulatory dendritic cells and corresponding mechanism / 中华创伤杂志

ABSTRACT

ObjectiveTo observe the effects of high mobility group box-1 protein ( HMGB1 ) on function of murine spleen IL-10-producing dendritic cells (DCs) subset CD11clowCD45RBhighDCs.MethodsSplenic CD11clowCD45RBhighDCs and CD4 +T cells in Balb/c mice were purified by magnetic beads sorting.CD11clowCD45RBhighDCs were treated with various doses of HMGB1 (0,20,100,500ng/ml).Flow cytometry was used to determine expressions of CD11clowCD45RBhighDC surface molecules including CD40,CD80,CD86,Ⅰ-a/e and Toll-like receptor (TLR) 4.IL-10 level in CD11clow CD45RBhighDC culture supernatants was determined by ELISA method.The CD4+ T cells were divided into four groups control group (without only treatment),untreated group (HMGB1-untreated CD11clow CD45RBhigh DCs plus CD4+T cells),high-dose HMGB1-treated group (500 ng/ml HMGB1-treated CD11clowCD45RBhigh DCs plus CD4 +T cells),high-dose HMGB1-treated + antibody 1 group (500 ng/ml HMGB1-treated CD11clowCD45RBhigh DCs plus IL-10 antibody and CD4+T cells),high-dose HMGB1-treated + antibody 2 group (500 ng/ml HMGB1-treated CD11clow CD45RBhigh DCs plus homotype IL-10 antibody and CD4 +T cells).IL-4 as well as interferon( IFN-γ) contents in CD4 + T cell culture supernatants were determined by flow cytometry.ResultsHMGB1 could markedly enhance the expressions of CD40,CD86 and TLR4 on CD11clowCD45RBhigh DC surface as well as level of IL-10 secreted by CD11clow CD45RBhigh DCs as compared with the non-HMGB1 treatment.Meantime,the secretion of IL-10 was HMGB1 concentration dependent.IFN-γ level in high-dose HMGB1-treated group was (279 ± 17) pg/ml,which was markedly lower than that in the untreated group [ (963 ± 11 ) pg/ml,P ＜ 0.05 \ ].IL-4 level in high-dose HMGB1-treated group was (372 ± 14) pg/ml,which was significantly higher than that in the untreated group [ (213 ± 10) pg/ml,P ＜0.05) \].ConclusionsHMGB1 promotes IL-10 production in CD11clowCD45RBhighDCs,induces the differentiation of CD4 +T cells to Th2 cells and downregulates the immune response via activating CD11clowCD45RBhigh DCs.