SALMONELLA HIJACKING OF STAT3 AND CONSEQUENCES FOR DISEASE

沙门氏菌引起估计1.5亿例胃肠炎和2500万例侵袭性疾病 （肠热病和非伤寒菌血症），每年导致30万人死亡。操纵沙门氏菌 通过分泌的效应蛋白的多种宿主细胞途径，但是大多数效应物的分子功能， 特别是在动物和人类中，仍然知之甚少。沙门氏菌是如何 效应子的功能和它们靶向的途径是了解效应子如何影响感染及其 对慢性炎症性疾病（如炎症性肠病（IBD））的长期影响。IBD是 IBD是一种免疫介导的疾病，IBD是否受到先前沙门氏菌感染的影响尚不清楚， 流行病学和小鼠研究的证据相互矛盾。为了了解急性沙门氏菌 感染可能会影响长期的免疫调节，需要研究以确定特定的沙门氏菌 效应物靶向宿主免疫调节途径，这些变化是否在感染后持续存在，如果这些变化持续存在， 变化调节疾病的风险或严重程度。 通过沙门氏菌血清型的比较基因组学，我们最近鉴定了一种新的原噬菌体编码的 III分泌的效应物：沙门氏菌抗炎反应激活剂（SarA）。萨拉是唯一的沙门氏菌 效应器被证明是必要的和足够的激活STAT 3（信号转导和激活剂， 转录-3），一种调节免疫细胞增殖、发育和自身免疫的关键转录因子， 包括IBD。SarA介导的STAT 3操纵在宿主细胞中重编程转录， 增加小鼠的毒性。我们假设SarA对注射效应子的细胞有直接作用， 由于STAT 3靶基因（如抗炎细胞因子IL-10）的继发性后果， 在感染清除后引起持续变化。因此，本申请的目的是 确定SarA如何激活STAT 3并在感染期间和感染后影响免疫细胞群体。 基于初步数据，我们假设SarA直接结合STAT 3和辅因子，组装成一个STAT 3- 启动平台。该途径的激活使多种细胞类型中的STAT 3磷酸化，但尚不清楚 体内靶向哪些细胞以及在感染期间和之后这种激活的后果是什么。 因此，我们提出了具体的目标：1）确定SarA如何通过生物化学途径驱动STAT 3激活 和遗传方法，2）确定SarA对免疫细胞群体和长期的影响， 对宿主的后果，包括结肠炎中肠道炎症的严重程度。在完成这些 我们将确定SarA如何介导STAT 3信号传导以及这些信号传导事件如何/是否改变 感染期间和感染后的免疫功能。揭示这些机制可能会导致新的治疗方法 用于治疗沙门氏菌病以及其他STAT 3依赖性病理状况的策略， 自身免疫性疾病、癌症和其他传染病。

Salmonellae cause an estimated 150 million cases of gastroenteritis and 25 million cases of invasive disease (enteric fever and non-typhoidal bacteremia), leading to 300,000 deaths per year. Salmonella manipulates multiple host cellular pathways through secreted effector proteins, but the molecular functions of most effectors, especially in animals and humans, remain poorly understood. A thorough characterization of how Salmonella effectors function and the pathways they target is required to understand how effectors impact infection and their long-term consequences on chronic inflammatory conditions, such as inflammatory bowel disease (IBD). IBD is an immune-mediated disease and whether IBD is affected by previous Salmonella infection is unclear, with conflicting evidence from both epidemiological and mouse studies. To understand how acute Salmonella infections may impact long-term immune modulation, studies are needed to determine how specific Salmonella effectors target host immune regulatory pathways, whether these changes persist beyond infection, and if these changes modulate risk or severity of disease. Through comparative genomics of Salmonella serovars, we recently identified a novel prophage-encoded Type III secreted effector: Salmonella anti-inflammatory response activator (SarA). SarA is the only Salmonella effector demonstrated to be necessary and sufficient to activate STAT3 (signal transducer and activator of transcription-3), a key transcription factor that regulates immune cell proliferation, development, and autoimmune conditions including IBD. SarA-mediated manipulation of STAT3 reprograms transcription in host cells and increases virulence in mice. We hypothesize SarA has both direct effects on cells injected with the effector and secondary consequences due to STAT3 target genes (such as the anti-inflammatory cytokine IL-10) that may cause persistent changes after infection has cleared. Therefore, the objective of this application is to determine how SarA activates STAT3 and affects immune cell populations during and after infection. Based on preliminary data, we hypothesize that SarA directly binds STAT3 and cofactors to assemble a STAT3- activating platform. Activation of this pathway phosphorylates STAT3 in multiple cell types, but it is unknown which cells are targeted in vivo and what the consequences of this activation are during and after infection. Therefore, we propose Specific Aims to 1) determine how SarA drives STAT3 activation through biochemical and genetic approaches and 2) determine the effects of SarA on immune cell populations and long-term consequences for the host, including severity of intestinal inflammation in colitis. Following completion of these aims, we will have determined how SarA mediates STAT3 signaling and how/if these signaling events alter immune function during and after infection. Revealing these mechanisms could lead to new therapeutic strategies for treating salmonellosis, as well as other STAT3-dependent pathological conditions including autoimmune diseases, cancer, and other infectious diseases.