IL-10+ regulatory B cells (Bregs) show great promise in treating graft-versus-host disease (GVHD), a life-threatening complication of post-hematopoietic stem cell transplantation. However, obtaining high-quality human IL-10+ Bregs in vitro remains a challenge due to the lack of unique specific markers and the triggering of pro-inflammatory cytokine expression. Here, by uncovering the critical signaling pathways in Breg induction by mesenchymal stromal cells (MSCs), we first established an efficient Breg induction system based on MSCs and GSK-3β blockage (CHIR-99021), which had a robust capacity to induce IL-10+ Bregs while suppressing tumor necrosis factor α (TNF-α) expression. Furthermore, these Breg populations could be identified and enriched by CD1c+. Mechanistically, MSCs induced the expansion of Bregs through the PKA-mediated phosphorylation of cAMP response element-binding protein (CREB). Thus, we developed a chemically defined inducing protocol by PKA-CREB agonist, instead of MSCs, which can also effectively induce CD1c+ Bregs with lower TNF-α expression. Importantly, induced CD1c+ Bregs suppressed the proliferation of peripheral blood mononuclear cells and the inflammatory cytokine secretion of T cells. When adoptively transferred into a humanized mouse model of GVHD, induced CD1c+ Bregs effectively alleviated GVHD. Overall, we established an efficient ex vivo induction system for human Bregs, which has implications for developing novel Bregs-based therapies for GVHD.

中文翻译：

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通过化学定义的系统，离体生成的人 CD1c+ 调节性 B 细胞抑制免疫反应并减轻移植物抗宿主病


IL-10+ 调节性 B 细胞 （Bregs） 在治疗移植物抗宿主病 （GVHD） 方面显示出巨大的前景，GVHD 是造血干细胞移植后危及生命的并发症。然而，由于缺乏独特的特异性标志物和触发促炎细胞因子表达，在 体外获得高质量的人 IL-10 + Breg 仍然是一个挑战。在这里，通过揭示间充质基质细胞 （MSC） 诱导 Breg 的关键信号通路，我们首先建立了一种基于 MSC 和 GSK-3β 阻断 （CHIR-99021） 的高效 Breg 诱导系统，该系统具有诱导 IL-10+ Bregs 的强大能力，同时抑制肿瘤坏死因子 α （TNF-α） 表达。此外，这些 Breg 群体可以通过 CD1c+ 进行识别和富集。从机制上讲，MSC 通过 PKA 介导的 cAMP 反应元件结合蛋白 （CREB） 磷酸化诱导 Bregs 的扩增。因此，我们开发了一种由 PKA-CREB 激动剂代替 MSC 的化学定义的诱导方案，它也可以有效诱导具有较低 TNF-α 表达的 CD1c+ Bregs。重要的是，诱导的 CD1c+ Bregs 抑制了外周血单核细胞的增殖和 T 细胞的炎性细胞因子分泌。当过继转移到 GVHD 人源化小鼠模型中时，诱导的 CD1c+ Bregs 有效缓解了 GVHD。总体而言，我们建立了一种高效的人类 Bregs 离体诱导系统，这对开发基于 Bregs 的新型 GVHD 疗法具有重要意义。