Adenosine receptor-mediated effects of Clostridium difficile toxins in humans

项目总结/摘要 艰难梭菌感染（CDI）是感染性腹泻的最常见原因。 已知引起CDI的主要毒力因子是两种毒素：TcdA和TcdB。这些毒素 引起肠组织的强烈炎症，严重时引起体循环的炎症。腺苷 在组织损伤时释放量增加，其作用由四种受体-A1、A2 A、A2 B介导 和A3腺苷受体（AR）。我们已经表明，TcdA和TcdB上调A2 BAR，并降低A2 BAR的表达。 程度，A2 AAR，转录本在人肠细胞系中的表达。A2 BAR的抑制或缺失降低 TcdA诱导的回肠袢和感染小鼠的分泌和粘膜损伤。A2 AAR和A2 BAR 已知存在于免疫细胞中，肠上皮细胞表达的A2 BAR转录物水平高于 其他细胞类型。我们假设腺苷通过与A2 BAR和A2 AAR的相互作用， 调节宿主对C.艰难梭菌毒素这些腺苷的药理学操作 受体将改善毒素诱导的上皮损伤并改善感染期间的结果。在这 因此，我们将确定A2 BAR抑制如何调节局部炎症反应。艰难 原代人肠组织中的毒素（目标1）。我们还将确定A2 AAR激活如何调节 对C.人嗜中性粒细胞中的艰难梭菌毒素（Aim 2）。该研究计划将 深入了解A2 AAR和A2 BAR信号传导如何介导宿主对C.艰难梭菌毒素和 这些受体的操纵如何提供新型、非抗菌、针对宿主的方法， 治疗CDI。

PROJECT SUMMARY/ABSTRACT Clostridium difficile infection (CDI) is the single most common cause of infectious antibiotic-induced diarrhea. The primary virulence factors that are known to cause CDI are the two toxins: TcdA and TcdB. These toxins incite intense inflammation of the intestinal tissue and in severe cases, of the systemic circulation. Adenosine is released in increased amounts during tissue injury and its action is mediated by four receptors—A1, A2A, A2B and A3 adenosine receptors (AR). We have shown that TcdA and TcdB upregulate A2BAR and to lesser extent, A2AAR, transcript expression in a human intestinal cell line. Inhibition or deletion of A2BARs decreases TcdA-induced secretion and mucosal injury in ileal loops and in infected mice. While both A2AARs and A2BARs are known to be present in immune cells, gut epithelial cells express higher levels of A2BAR transcript than other cell types. We hypothesize that adenosine, through its interactions with A2BAR and A2AAR, modulates host responses to C. difficile toxins. Pharmacologic manipulation of these adenosine receptors will ameliorate toxin-induced epithelial injury and improve outcomes during infection. In this proposal, we shall determine how A2BAR inhibition regulates the local inflammatory responses to C. difficile toxins in primary human intestinal tissue (Aim 1). We shall also determine how A2AAR activation modulates systemic inflammatory responses to C. difficile toxins in human neutrophils (Aim 2). This research plan will provide insight into how A2AAR and A2BAR signaling mediate host immune responses to C. difficile toxins and how manipulation of these receptors may provide novel, non-antimicrobial, host-directed approaches to treating CDI.