Molecular chaperones and immune tolerance

项目摘要 gp96是内质网内腔中的免疫伴侣，用于折叠和组装 免疫应答中的多种关键受体，包括TLR和整合素。gp96的失调已经被 与一些类风湿性疾病如狼疮有关。我们最近发现gp96也是 对于调节性T细胞的稳定性和体内抑制功能至关重要（Zhang等，J Clin 2015年投资）。此外，我们还发现gp96是细胞表面折叠的重要分子伴侣 TGFb的对接受体GARP（也称为LRRC32），其表达被认为限于 凝血酶和血小板。有趣的是，我们发现在TLR连接后，B细胞而不是骨髓细胞表达GARP， 并且在小鼠狼疮模型和人狼疮模型中均存在处于稳定状态的独特的GARP+ B细胞群体。 SLE患者。 从本质上讲，我们现在已经确定gp96调节免疫和耐受的几个关键方面。是 这是通过陪伴TLR来启动免疫应答的最佳树突状细胞活化所必需的。GP96也 通过赋予Treg细胞的抑制功能，在免疫耐受中起重要作用。免疫VS 因此，耐受性命运的确定可以由GP96以上下文和细胞类型特异性的方式协调。 我们假设gp96通过调节细胞表面TGF β的生物利用度来控制免疫耐受， T细胞和B细胞。这是通过gp96在折叠GARP和GRP中的内在伴侣功能来实现的。 整合素，前者参与从细胞外环境中抓取和结合潜在的TGF β， 旁分泌方式，而后者参与TGF β激活。这一新的假设将通过以下方式加以解决： 以下两个具体目标： 我们的第一个目标将集中在了解gp96在控制Treg细胞功能的机制。我们的第二 本研究旨在确定B细胞内源性GARP在基础B细胞生物学中的作用，并探讨其在肿瘤发病机制中的作用。 狼疮，通过利用我们令人兴奋的初步数据，证明GARP在减弱 实验性狼疮因此，这两个目标将在正常和致病条件下追求。一些 将使用新的遗传模型，包括诱导型和细胞特异性GARP敲除小鼠。我们认为 我们的假设的充分阐明将对理解细胞的难以捉摸的作用具有根本的意义。 表面TGF β在免疫耐受中的作用，以及在狼疮的发病机制中的作用。

PROJECT SUMMARY gp96 is an immune chaperone in the lumen of the endoplasmic reticulum, for the folding and assembly of multiple key receptors in immune responses including TLRs and integrins. Dysregulation of gp96 has been linked with a number of rheumatoid diseases such as lupus. We discovered very recently that gp96 is also critically required for the stability and in vivo suppressive function of regulatory T cells (Zhang et al., J Clin Invest 2015). Furthermore, we unveiled that gp96 serves as an essential chaperone for folding the cell surface docking receptor for TGFb, GARP (known also as LRRC32), whose expression is thought to be restricted to Tregs and platelets. Intriguingly, we found that B cells but not myeloid cells express GARP upon TLR ligation, and there is a unique population of GARP+ B cells in the steady state in both mouse lupus models and human patients with SLE. In essence, we have now established that gp96 regulates several key aspects of immunity and tolerance. It is required for optimal dendritic cell activation via chaperoning TLRs to initiate immune responses. gp96 also plays essential roles for immune tolerance by endowing suppressive function of Treg cells. The immunity vs. tolerance fate determination thus could be orchestrated by gp96 in a contextual and cell type specific fashion. We hypothesize that gp96 controls immune tolerance by regulating the bioavailability of cell surface TGFb for Tregs and B cells. This is accomplished by the intrinsic chaperone function of gp96 in folding both GARP and integrins, the former is involved in snatching and binding latent TGFb from the extracellular milieu in a paracrine fashion, whereas the latter is involved in TGFb activation. This novel hypothesis will be addressed by the following two specific aims: Our first Aim will focus on understanding the mechanisms of gp96 in controlling Treg cell function. Our second Aim will determine the roles of B cell-intrinsic GARP in fundamental B cell biology and the pathogenesis of lupus, by taking advantage of our exciting preliminary data demonstrating the roles of GARP in attenuating experimental lupus. Thus, the two aims will be pursued in both normal and pathogenic conditions. A number of novel genetic models including inducible and cell-specific GARP knockout mice, will be used. We believe that full elucidation of our hypothesis will have fundamental implications in understanding the elusive roles of cell surface TGFb in immune tolerance, as well as in the pathogenesis of lupus.