■自身免疫性疾病的发病率,1型糖尿病(T1D),在世界范围内一直在增加,最近的研究表明,肠道微生物群与调节对T1D的敏感性有关。Toll样受体5(TLR5)识别细菌鞭毛蛋白,并在许多细胞上广泛表达,包括树突状细胞(DC),这是有效的抗原呈递细胞(APC)。TLR5调节对肥胖的易感性,并通过肠道微生物群改变新陈代谢;然而,对TLR5在自身免疫中的作用知之甚少,尤其是在T1D。
■为了填补这一知识空白,我们产生了缺乏TLR5的非肥胖糖尿病(NOD)小鼠,人类T1D的动物模型,用于研究。
■我们发现TLR5缺乏导致子宫内CD11c+DC发育减少,在微生物定植之前,一直维持到成年。这与表达CD103,有或没有CD8α共表达的DC群体的偏倚有关,以及不同细胞因子的过度分泌,在体外(刺激后)和直接离体。我们还发现缺乏TLR5的DC能够促进多克隆和胰岛抗原特异性CD4+T细胞增殖和促炎细胞因子分泌。有趣的是,与野生型小鼠相比,只有年龄较大的TLR5缺陷型NOD小鼠发生自发性T1D的风险更大.
■总之,我们的数据显示TLR5调节DC发育并增强细胞因子分泌和糖尿病性CD4+T细胞应答.对TLR5在DC发育和自身免疫性糖尿病中的作用的进一步研究可能会提供对1型糖尿病发病机理的更多见解。
The incidence of the autoimmune disease, type 1 diabetes (T1D), has been increasing worldwide and recent studies have shown that the gut microbiota are associated with modulating susceptibility to T1D. Toll-like receptor 5 (
TLR5) recognizes bacterial flagellin and is widely expressed on many cells, including dendritic cells (DCs), which are potent antigen-presenting cells (APCs).
TLR5 modulates susceptibility to obesity and alters metabolism through gut microbiota; however, little is known about the role
TLR5 plays in autoimmunity, especially in T1D.
To fill this knowledge gap, we generated a
TLR5-deficient non-obese diabetic (NOD) mouse, an animal model of human T1D, for study.
We found that TLR5-deficiency led to a reduction in CD11c+ DC development in utero, prior to microbial colonization, which was maintained into adulthood. This was associated with a bias in the DC populations expressing CD103, with or without CD8α co-expression, and hyper-secretion of different cytokines, both in vitro (after stimulation) and directly ex vivo. We also found that
TLR5-deficient DCs were able to promote polyclonal and islet antigen-specific CD4+ T cell proliferation and proinflammatory cytokine secretion. Interestingly, only older TLR5-deficient NOD mice had a greater risk of developing spontaneous T1D compared to wild-type mice.
In summary, our data show that TLR5 modulates DC development and enhances cytokine secretion and diabetogenic CD4+ T cell responses. Further investigation into the role of TLR5 in DC development and autoimmune diabetes may give additional insights into the pathogenesis of Type 1 diabetes.