Effects of short-chain fatty acids in inhibiting HDAC and activating p38 MAPK are critical for promoting B10 cell generation and function

Fagui Zou,Yi Qiu,Yilian Huang,Qingru Niu,Hang Zou,Jianbo Sun,Xiao Cheng,Aoxiang Luo

doi:10.1038/s41419-021-03880-9

Fagui Zou, Yi Qiu + Show 6 more

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https://doi.org/10.1038/s41419-021-03880-9

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Abstract

B10 cells are regulatory B cells capable of producing IL-10 for maintaining immune homeostasis. Dysregulation of B10 cells occurs in autoimmune and inflammatory diseases. Modulation or adoptive transfer of B10 cells is a promising therapeutic strategy. The short-chain fatty acids (SCFAs), the metabolites of microbiota, play a critical role in maintaining immune homeostasis and are the potential drugs for the modulation of B10 cells. It is not clear whether and how SCFAs upregulate the frequency of B10 cells. Here, we found that SCFAs could promote murine and human B10 cell generation in vitro. Upregulation of B10 cells by butyrate or pentanoate was also observed in either healthy mice, mice with dextran sodium sulfate (DSS)-induced colitis, or mice with collagen-induced arthritis. Moreover, SCFA treatment could ameliorate clinical scores of colitis and arthritis. Adoptive transfer of B cells pretreated with butyrate showed more alleviation of DSS-induced colitis than those without butyrate. A further study demonstrates that SCFAs upregulate B10 cells in a manner dependent on their histone deacetylase (HDAC) inhibitory activity and independent of the G-protein-coupled receptor pathway. Transcriptomic analysis indicated that the MAPK signaling pathway was enriched in B10 cells treated with butyrate. A study with inhibitors of ERK, JNK, and p38 MAPK demonstrated that activating p38 MAPK by butyrate is critical for the upregulation of B10 cells. Moreover, HDAC inhibitor has similar effects on B10 cells. Our study sheds light on the mechanism underlying B10 cell differentiation and function and provides a potential therapeutic strategy with SCFAs and HDAC inhibitors for inflammation and autoimmune diseases.

Highlights

Introduction RegulatoryB cells (Bregs) are immunosuppressive B lymphocytes capable of secreting immunomodulatory cytokines such as interleukin-10 (IL-10), IL-35, and transforming growth factor-beta (TGF-β)[1,2,3,4]
We checked the effects of CD40 monoclonal antibody, CpG, and lipopolysaccharide (LPS), the stimuli used usually for B cell culture, on B10 cell differentiation via BCR, TLR9, and TLR4 signaling pathways, respectively
Human B10 cell generation could be enhanced by sodium butyrate (NaBu) when human peripheral blood mononuclear cells (PBMCs) were cultured with CD40 monoclonal antibody (mAb), LPS, or CpG (Fig. 1C)

Summary

Introduction

Introduction RegulatoryB cells (Bregs) are immunosuppressive B lymphocytes capable of secreting immunomodulatory cytokines such as interleukin-10 (IL-10), IL-35, and transforming growth factor-beta (TGF-β)[1,2,3,4]. A Representative FACS plots of splenic B cells purified from C57BL/ 6J mice and cultured with murine CD40 mAb or LPS in the absence or presence of corresponding SCFAs (0.5 mM) for 48 h. B Representative FACS plots of murine splenic B cells cultured with CpG-1826 or CpG-2395 and incubated with or without NaBu. C Representative FACS plots of human PBMCs stimulated by LPS, CpG-ODN 2395, or human CD40 mAb with or without sodium butyrate (0.5 mM) for 48 h. E Statistical mRNA level of IL-10 and PRDM1 detected by RT-qPCR in purified murine B cells cultured with or without SCFAs under the existence of CD40 mAb for 48 h. F Statistical mRNA level of PRDM1 detected by RT-qPCR in purified murine B cells cultured with or without SCFAs under the existence of CD40 mAb or LPS for 48 h. The data are presented as mean ± SD from at least three independent experiments. *P < 0.05, **p < 0.01, ***p < 0.001, and ****p < 0.0001 compared to Ctrl with the same stimuli

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