Loss of Gαq impairs regulatory B-cell function

Yan He; Xiaoqing Yuan; Yan Li; Chunlian Zhong; Yuan Liu; Hongyan Qian; Jingxiu Xuan; Lihua Duan; Guixiu Shi

doi:10.1186/s13075-018-1682-0

Loss of Gαq impairs regulatory B-cell function

Arthritis Res Ther. 2018 Aug 24;20(1):186. doi: 10.1186/s13075-018-1682-0.

Authors

Yan He¹, Xiaoqing Yuan^{1

2}, Yan Li¹, Chunlian Zhong¹, Yuan Liu¹, Hongyan Qian¹, Jingxiu Xuan¹, Lihua Duan³, Guixiu Shi⁴

Affiliations

¹ Department of Rheumatology and Clinical Immunology, The First Affiliated Hospital of Xiamen University, Xiamen, China.
² Ningbo City Medical Treatment Center Lihuili Hospital, No. 57 Xingning Road, Ningbo, 315000, China.
³ Department of Rheumatology and Clinical Immunology, The First Affiliated Hospital of Xiamen University, Xiamen, China. lh-duan@163.com.
⁴ Department of Rheumatology and Clinical Immunology, The First Affiliated Hospital of Xiamen University, Xiamen, China. gshi@xmu.edu.cn.

Abstract

Background: Recent studies have shown a crucial role of Gαq in immune regulation, but how Gαq 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 Gαq on Breg differentiation, which were confirmed by western blot analysis. Furthermore, the expression level of Gαq was assessed by quantitative real-time PCR in peripheral blood mononuclear cells (PBMCs) from healthy controls and rheumatoid arthritis patients. The frequency of CD19⁺CD24^hiCD38^hi B cells in PBMCs was detected by flow cytometry, and the association of the Gαq mRNA expression level and the frequency of CD19⁺CD24^hiCD38^hi B cells was analyzed by Spearman test.

Results: The differentiation of CD19⁺IL-10⁺ Bregs was inhibited in the Gnaq^-/- mice. In addition, Gαq 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 Gαq on Bregs, and blockage of these signaling pathways impaired Breg differentiation. Consistent with our previous studies, we also found a decreased frequency of CD19⁺CD24^hiCD38^hi Bregs in rheumatoid arthritis patients. As expected, a significantly positive correlation was investigated between CD19⁺CD24^hiCD38^hi Bregs with Gαq mRNA expression.

Conclusions: Our results indicate that Gαq plays a critical role in the differentiation and immunosuppression of Bregs, and it may provide a new therapeutic target for autoimmune diseases.

Keywords: Gαq; IL-10; Regulation; Regulatory B cells.

Publication types

Research Support, Non-U.S. Gov't

MeSH terms

Adult
Aged
Animals
Arthritis, Rheumatoid / immunology
B-Lymphocytes, Regulatory / immunology*
Cell Differentiation / immunology*
Female
GTP-Binding Protein alpha Subunits, Gq-G11 / immunology*
Humans
Lymphocyte Activation / immunology*
Male
Mice
Mice, Inbred C57BL
Mice, Knockout
Middle Aged

Substances

GTP-Binding Protein alpha Subunits, Gq-G11