Loss of G?q impairs regulatory B-cell function.

ABSTRACT: BACKGROUND:Recent studies have shown a crucial role of G?q in immune regulation, but how G?q modulates regulatory B-cell (Breg) function is still unclear. We address this here. METHODS:CD19+IL-10+ Bregs of wild-type (WT) and Gnaq-/- mice were analyzed by flow cytometry after stimulation by lipopolysaccharide. The WT and Gnaq-/- Bregs were isolated and cocultured with WT CD4+CD25- T cells in the presence of T-activator, and the proliferation of T cells and differentiation of regulatory T cells (Tregs) were analyzed by flow cytometry. We used inhibitors of PI3 kinase (PI3K), extracellular regulated protein kinases 1/2 (Erk1/2), and p38 mitogen-activated protein kinase (p38 MAPK) to detect the pathways involved in the regulation of G?q on Breg differentiation, which were confirmed by western blot analysis. Furthermore, the expression level of G?q was assessed by quantitative real-time PCR in peripheral blood mononuclear cells (PBMCs) from healthy controls and rheumatoid arthritis patients. The frequency of CD19+CD24hiCD38hi B cells in PBMCs was detected by flow cytometry, and the association of the G?q mRNA expression level and the frequency of CD19+CD24hiCD38hi B cells was analyzed by Spearman test. RESULTS:The differentiation of CD19+IL-10+ Bregs was inhibited in the Gnaq-/- mice. In addition, G?q depletion showed an impaired suppressive function of Bregs on T-cell proliferation, which might be due to the decreased Treg expansion. Mechanically, our data demonstrated that the PI3K, Erk1/2, and p38 MAPK signaling pathways were required for regulation of G?q on Bregs, and blockage of these signaling pathways impaired Breg differentiation. Consistent with our previous studies, we also found a decreased frequency of CD19+CD24hiCD38hi Bregs in rheumatoid arthritis patients. As expected, a significantly positive correlation was investigated between CD19+CD24hiCD38hi Bregs with G?q mRNA expression. CONCLUSIONS:Our results indicate that G?q plays a critical role in the differentiation and immunosuppression of Bregs, and it may provide a new therapeutic target for autoimmune diseases.

SUBMITTER: He Y 

PROVIDER: S-EPMC6109260 | biostudies-literature | 2018 Aug

REPOSITORIES: biostudies-literature