Molecular basis of intestinal cryptosporidiosis

摘要 在晚期HIV感染者中，隐孢子虫仍然是一种与艾滋病相关的重要机会性感染 诊断或无法访问HAART。这种寄生虫感染人类的胃肠道上皮； 感染也是发展中国家幼儿腹泻的常见原因。目前没有 对感染有完全有效的治疗方法。隐孢子虫被称为“微侵袭”。 粘膜病原体和上皮抗菌防御是粘膜天然抗隐孢子虫的关键 豁免权。鉴于众所周知，需要II型干扰素-γ(干扰素-γ)来预防 肠道隐孢子虫病的发展，最近的进展揭示了I型干扰素的显著应答 例如，在微小弧菌感染后宿主上皮细胞中诱导干扰素-α和干扰素-β。分子 I型干扰素应答的潜在机制及其在隐孢子虫病发病机制中的潜在作用 不清楚。 微小隐孢子虫病毒1 (CSpV1)是细小病毒科、隐孢子虫病毒属的一员 感染微小隐孢子虫和其他隐孢子虫。我们最近的研究表明，寄主传递的 宿主-寄生虫交界处的CSpV1-RNA可以在宿主细胞中触发I型干扰素反应。细小隐孢子虫感染 减弱肠上皮细胞对干扰素-γ刺激的反应(即，受感染的细胞对 干扰素-γ激活)。令人惊讶的是，敲除肠上皮细胞中的I型干扰素信号或抑制 CSpV1RNA可以恢复细胞对干扰素-γ刺激的反应，并促进对微小弧菌的抗性 感染，提示I型干扰素信号对上皮性抗隐孢子虫防御有负面影响。 基于这些观察结果，我们假设隐孢子虫感染会触发I型干扰素反应 CSpV1-γ介导的肠上皮细胞抗微生物防御作用 RNA。我们将使用体外，体外，体内感染模型和互补的生化，分子， 和形态学方法阐明隐孢子虫感染的分子机制 在肠道上皮细胞中触发I型干扰素基因转录(目标1)，决定隐孢子虫如何 感染对感染的肠上皮细胞中JAK/STAT信号的调节(AIM 2)，并确定其影响 研究隐孢子虫诱导的JAK/STAT信号异常在上皮抗寄生虫防御中的作用(目标3)。这个 该提案在概念上具有创新性，因为它测试了共生CSpV1在肺炎发病机制中的新机制。 隐孢子虫病，并有可能为未来新的治疗策略的发展提供信息。

Summary Cryptosporidium remains a significant AIDS-related opportunistic infection among people with late HIV diagnosis or without access to HAART. This parasite infects the gastrointestinal epithelium in humans; infection is also a common cause of diarrhea in young children in developing countries. There is currently no fully effective therapy available for the infection. Cryptosporidium has been referred as a “minimally invasive” mucosal pathogen, and epithelial antimicrobial defense is key to mucosal innate anti-Cryptosporidium immunity. Whereas it is well appreciated that Type II interferon-gamma (IFN-γ) is required for preventing development of intestinal cryptosporidiosis, recent advances have revealed a significant Type I IFN response (e.g., induction of IFN-alpha and IFN-beta) in host epithelium following C. parvum infection. The molecular mechanisms underlying Type I IFN response and its potential role in the pathogenesis of cryptosporidiosis are unclear. Cryptosporidium parvum virus 1 (CSpV1) is a member of the family Partitiviridae, genus Cryspovirus that infects C. parvum and other Cryptosporidium spp. Our recent studies demonstrate that host delivery of CSpV1-RNAs at the host-parasite interface can trigger a Type I IFN response in host cells. C. parvum infection attenuates intestinal epithelial cell response to IFN-γ stimulation (i.e., infected cells are less susceptible to activation by IFN-γ). Surprisingly, knockout Type I IFN signaling in intestinal epithelial cells or inhibition of CSpV1-RNA delivery can restore cellular response to IFN-γ stimulation and promotes resistance to C. parvum infection, suggesting a negative impact of Type I IFN signaling on epithelial anti-Cryptosporidium defense. Based on these observations, we hypothesize that cryptosporidial infection triggers Type I IFN response in the intestinal epithelium and attenuates IFN-γ-mediated epithelial antimicrobial defense through delivery of CSpV1- RNAs. We will use in vitro, ex vivo, and in vivo infection models and complementary biochemical, molecular, and morphologic approaches to elucidate the molecular mechanisms by which Cryptosporidium infection triggers Type I IFN gene transcription in the intestinal epithelium (Aim 1), determine how Cryptosporidium infection modulates the JAK/STAT signaling in infected intestinal epithelial cells (Aim 2), and define the impact of Cryptosporidium-induced JAK/STAT signaling dysregulation on epithelial anti-parasite defense (Aim 3). The proposal is conceptually innovative as it tests a novel mechanism for symbiotic CSpV1 in the pathogenesis of cryptosporidiosis and has the potential to inform future development of new therapeutic strategies.