Adenosine receptor-mediated effects of Clostridium difficile toxins in humans

项目摘要/摘要 艰难梭菌感染(CDI)是感染性抗生素所致腹泻最常见的单一原因。 已知的导致CDI的主要毒力因素是两种毒素：TcdA和TcdB。这些毒素 煽动肠道组织严重发炎，严重者引发全身循环发炎。腺苷 在组织损伤过程中释放的量增加，其作用由四个受体介导-A1，A2A，A2B A3腺苷受体(AR)。我们已经证明，TcdA和TcdB上调A2BAR和 A2AAR，转录本在人肠道细胞系中的表达。A2BARs的抑制或缺失减少 TcdA诱导回肠和感染小鼠的分泌物和粘膜损伤。而A2AAR和A2BAR 已知存在于免疫细胞中，肠道上皮细胞表达的A2BAR转录本水平高于 其他细胞类型。我们假设，腺苷通过与A2BAR和A2AAR的相互作用， 调节宿主对艰难梭菌毒素的反应。这些腺苷的药理作用 受体将改善毒素引起的上皮损伤，并在感染期间改善预后。在这 我们将确定A2BAR抑制如何调节艰难梭菌的局部炎症反应。 原生人类肠道组织中的毒素(目标1)。我们还将确定A2AAR的激活是如何调节的 人类中性粒细胞对艰难梭菌毒素的全身炎症反应(目标2)。这项研究计划将 深入了解A2AAR和A2BAR信号如何介导宿主对艰难梭菌毒素和 这些受体的操纵如何提供新的、非抗菌的、宿主导向的方法 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.