HLA-B27 Misfolding an the UPR in Spondyloarthritis

描述(申请人提供)：人类白细胞抗原B27(B27)是导致脊柱性关节炎，特别是强直性脊柱炎的很大比例的遗传易感性的基因。尽管这些疾病的治疗有所改进，但治疗仍然不足，需要持续使用具有一定风险的药物。预计更好地了解致病机制，特别是B27的作用，将导致改进干预措施，并可能成为一种预防手段。由这笔资金资助的研究表明，B27是一种错误折叠的蛋白质。使用脊柱炎的动物模型，其中HLA-B27在大鼠(B27-TG大鼠)中表达，我们已经证明B27的错误折叠导致细胞内质网(ER)的压力，这反过来又激活了众所周知的未折叠蛋白反应(UPR)。初步研究结果表明，在Toll样受体(TLR)配体的刺激下，B27诱导的UPR导致巨噬细胞强烈过度表达一组细胞因子。我们把这称为普遍定期审议-TLR的协同作用。TLR是一种模式识别受体，允许细胞感知微生物产物并对其做出反应，它们在连接先天性免疫反应和获得性免疫反应方面发挥着重要作用。在B27诱导的UPR过程中，细胞过度产生的细胞因子可能会促进慢性免疫偏离，导致炎症，将蛋白质错误折叠与炎症性疾病联系起来。目标1中提出的研究将确定B27诱导的UPR激活对包括巨噬细胞和树突状细胞在内的免疫调节细胞产生细胞因子的影响，并建立UPR-TLR协同作用的UPR成分。在目标2中，我们将测试UPR-TLR协同作用是否导致CD4+T细胞的激活，并确定这种情况是否发生在B27-TG大鼠的炎症发展过程中。Aim 3中的研究使用转基因方法来调节人类白细胞抗原-B27诱导的UPR，以确定其在炎症中的作用。由于UPR-TLR协同作用而过度产生的下游细胞因子也将使用敲除方法进行靶向，以确定它们在疾病中的作用。这些研究将极大地促进我们对脊柱炎动物模型中的人类白细胞抗原-B27错误折叠和UPR的理解。这项工作有可能推动人类的翻译研究，并导致针对这种病理反应的新疗法的开发。

DESCRIPTION (provided by applicant): HLA-B27 (B27) is responsible for a large proportion of the genetic susceptibility to spondyloarthritis, particularly ankylosing spondylitis. Despite improvements in the treatment of these diseases, therapy remains inadequate and requires continual use of medications that carry definite risks. It is expected that a better understanding of pathogenic mechanisms, and specifically the role of B27, will lead to improved interventions and possibly a means of prevention. Studies funded by this grant have shown that B27 is a protein that misfolds. Using an animal model of spondyloarthritis, where HLA-B27 is expressed in rats (B27-Tg rats), we have shown that B27 misfolding causes stress in the endoplasmic reticulum (ER) of the cell, which in turn activates what is known as the unfolded protein response (UPR). Preliminary findings indicate that the B27-induced UPR causes macrophages to strongly overexpress a group of cytokines when stimulated by Toll-like receptor (TLR) ligands. We refer to this a UPR-TLR synergy. TLRs are pattern recognition receptors that allow cells to sense and respond to microbial products, and they play an important role in linking innate and adaptive immune responses. The cytokines overproduced by cells undergoing an B27-induced UPR may promote a chronic immune deviation resulting in inflammation, linking protein misfolding to an inflammatory disease. The studies proposed in Aim 1 will determine the effects of B27-induced UPR activation on the production of cytokines in immunoregulatory cells including macrophages and dendritic cells, and establish the UPR component of UPR-TLR synergy. In Aim 2 we will test whether UPR-TLR synergy causes activation of CD4+ T cells, and establish whether this occurs in B27-Tg rats during the development of inflammation. Studies in Aim 3 use a transgenic approach to modulate the HLA-B27-induced UPR to determine its role in inflammation. Downstream cytokines overproduced as a result of UPR-TLR synergy will also be targeted using a knockdown approach to determine their role in disease. These studies will significantly advance our understanding of HLA-B27 misfolding and the UPR in an animal model of spondyloarthritis. This work has the potential to drive translational studies in humans, and lead to the development of novel therapies targeting this pathological response.