Mechanism(s) of CD8 T cell-mediated Chlamydia-induced reproductive pathology

描述（由申请人提供）：由沙眼衣原体（一种细胞内细菌病原体）引起的性传播疾病影响全球约9000万人。对于未经治疗的女性，这些感染会引起严重的后遗症，例如盆腔炎和宫外孕，通常导致不孕。我们研究的长期目标是了解衣原体的发病机制和预防它们。预防这种后遗症的疫苗被认为是该问题的理想解决方案，并且努力集中于鉴定诱导稳健的CD 8 + T细胞应答的衣原体抗原，因为CD 8 + T细胞通常在清除细胞内病原体方面是有效的。然而，我们最近发现，能够产生TNF-α的CD 8 + T细胞介导上生殖道（UGT）病理，但在小鼠生殖器衣原体感染后，对衣原体清除的贡献最小。TNF-α通过两种主要受体TNF受体1（TNFR 1）和TNFR 2诱导包括凋亡的多效作用，这两种受体已显示在不同感染模型中相互补充或对抗作用。因此，TNFR 1的具体贡献 和TNFR 2在衣原体致病中的作用有待进一步研究，以探索治疗方法。 我们还发现，衣原体特异性的，而不是幼稚的，CD 8 + T细胞介导生殖器病理。CD 8 + T细胞对衣原体清除的贡献最小，这可能是由于衣原体感染的细胞表面上MHC I类表达的下调。鉴于此，似乎衣原体特异性CD 8 + T细胞不能有效地靶向感染的细胞，因此对衣原体清除的贡献最小;然而，它们被激活并可能通过靶向未感染的细胞引起病理学。这表明衣原体肽由未感染的细胞呈递给CD 8 + T细胞的可能性，但回避了问题：“未感染的细胞如何获得衣原体肽”？间隙连接介导的抗原转运（GMAT）现象可以解释这种范式。GMAT通过连接蛋白（Cx）蛋白形成的通道发生，主要是Cx43（由差距连接α 1基因或Gja 1表达）。连接蛋白43也在输卵管上皮上表达，已显示其参与抗原肽从感染细胞转移至旁观者未感染细胞并随后呈递至CD 8 + T细胞。这种机制可以解释这种细胞类型介导的衣原体清除的病理效应和低效率。然而，Cx43和GMAT在微生物诱导的体内系统免疫发病机制中的作用尚未得到证实。基于此，我们将测试我们的中心假设，即“CD 8 + T细胞通过TNF-α受体介导衣原体生殖病理学并靶向未感染的细胞”。我们将通过以下方式检验这一假设：目标1。确定TNF-α受体在CD 8 + T细胞介导的衣原体发病机制中的作用，目的2.确定连接蛋白43在CD 8 + T细胞介导的衣原体发病机制中的作用

DESCRIPTION (provided by applicant): Sexually transmitted diseases caused by Chlamydia trachomatis, an intracellular bacterial pathogen, affect approximately 90 million people worldwide. In untreated women, these infections cause serious sequelae such as pelvic inflammatory disease and ectopic pregnancy, often resulting in infertility. The long term goal of our research is to understand the mechanisms of chlamydial pathogenesis and prevent them. A vaccine to prevent such sequelae is thought to be an ideal solution to the problem, and efforts are focused on identifying of chlamydial antigens that induce a robust CD8+ T cell response, since CD8+ T cells are typically effective in clearance of intracellular pathogens. However, we have found recently that CD8+ T cells capable of producing TNF-a mediate upper genital tract (UGT) pathology, but contribute minimally to chlamydial clearance, following genital chlamydial infection in mice. TNF-a induces pleotrophic effects including apoptosis via two main receptors, TNF receptor 1 (TNFR1) and TNFR2, which have been shown to complement or oppose the effects of each other in different infection models. Therefore, the specific contributions of TNFR1 and TNFR2 in chlamydial pathogenesis need to be determined to explore therapeutic approaches in the future. We also have found that Chlamydia-specific, not na¿ve, CD8+ T cells mediate the genital pathologies. CD8+ T cells contribute minimally to chlamydial clearance possibly due to down- regulation of MHC class I expression on Chlamydia-infected cell surfaces. Given this, it appears that Chlamydia-specific CD8+ T cells do not target infected cells efficaciously and consequently contribute minimally to chlamydial clearance; nevertheless, they get activated and cause pathology possibly by targeting uninfected cells. This suggests the possibility that chlamydial peptides are presented to CD8+ T cells by uninfected cells, but begs the question: "How do uninfected cells acquire chlamydial peptides"? The phenomenon of gap junction mediated antigen transport (GMAT) may explain this paradigm. GMAT occurs via channels formed by connexin (Cx) proteins, predominantly Cx43 (expressed by the gap junction alpha 1 gene, or Gja1). Connexin 43, also expressed on oviduct epithelium, has been shown to be involved in the transfer of antigenic peptides from infected to bystander uninfected cells and subsequent presentation to CD8+ T cells. Such a mechanism would explain both the pathological effects and low efficiency of chlamydial clearance mediated by this cell type. However, the role of Cx43 and GMAT in microbe-induced immunopathogenesis in vivo systems has yet to be demonstrated. Based on this, we will test our central hypothesis that "CD8+ T cells mediate chlamydial reproductive pathology through TNF-a receptors and target uninfected cells". We will test this hypothesis by: Aim 1. Determine the role of TNF-a receptors in CD8+ T cell mediated chlamydial pathogenesis, and Aim 2. Determine the role of connexin 43 in CD8+ T cell mediated chlamydial pathogenesis