Effects of an immunostimulator CH2b on Th1/Th2 and Th17/Treg immune imbalance in RA mice

Objective To investigate the effects of a synthetic immunomodulator CH2b with a thiazolidin-4-one ring on Th1/Th2 and Th17/regulatory T cell (Treg) immune imbalance in a mouse model of rheumatoid arthritis (RA). Methods Forty-five DBA/1 mice were induced with mixed immunodominant peptides derived from glucose-6-phosphate isomerase (GPI) to establish the mouse model of rheumatoid arthritis (RA) and then were randomly divided into three groups: model group (without intervention), α-GalCer group ( treated with α-GalCer and used as positive control group) and CH2b group (treated with CH2b). Fifteen DBA/1 mice were selected to set up healthy control group. Cytometric bead array (CBA) was used to analyze the levels of TNF-α, IL-6, IL-4 and IFN-γ in serum samples. Mouse Th1/Th2/Th17 phenotyping kit was used to detect the percentages of Th1/Th2/Th17. The expression of T-bet, GATA-3, ROR-γt and Foxp3 at mRNA level in liver tissues were analyzed by PCR. Results (1) Compared with the healthy control group, serum IFN-γ, IL-6 and TNF-α levels in the model group began to rise on the 8th day and increased to peaks on the 14th day followed by gradual decreases. Serum IL-6 and TNF-α levels increased significantly on the 14th day (P 0.05). Compared with the model group, serum IFN-γ, IL-6 and TNF-α levels in α-GalCer and CH2b groups gradually decreased from the 8th day until the inflammation was relieved; serum IL-6 and TNF-α levels on the 14th day were down-regulated significantly (P<0.05), while serum IL-4 level on the 14th day was up-regulated. (2) Compared with the healthy control group, the model group showed significantly increased ratios of Th1 and Th17 subgroups (P<0.05), but decreased ratio of Th2 subgroup on the 8th day. Compared with the model group, α-GalCer and CH2b groups showed decreased ratio of Th1 subgroup, but significantly increased ratio of Th2 subgroup (P<0.05) on the 8th day. Compared with the healthy control group, ratios of Th1, Th2 and Th17 subgroups in the model group increased significantly on the 14th day (P<0.05). Compared with the model group, ratios of Th1, Th2 and Th17 subgroups in α-GalCer and CH2b groups decreased significantly on the 14th day (P<0.05). (3) Compared with the healthy control group, the model group showed increased expression of T-bet (P<0.05) and ROR-γt at mRNA level, but decreased expression of GATA-3 at mRNA level on the 14th day. Compared with the model group, α-GalCer and CH2b groups showed increased expression of GATA-3 (P<0.05) and Foxp3 at mRNA level, but decreased expression of T-bet at mRNA level (P<0.05) on the 14th day. Compared with the healthy control group, the model group showed increased ratios of T-bet to GATA-3 and ROR-γt to Foxp3 at mRNA level. Compared with the model group, α-GalCer and CH2b groups showed decreased ratios of T-bet to GATA-3 (P<0.05) and ROR-γt to Foxp3 at mRNA level. Conclusion CH2b can regulate the immune function of mice with RA by restoring Th1/Th2 and Th17/Treg immune balance, which suggestes its promising value for clinical application. Key words: Immunomodulator; Rheumatoid arthritis; Th1/Th2; Th17/Treg