Molecular basis of intestinal cryptosporidiosis

总结 隐孢子虫仍然是艾滋病晚期感染者中一种重要的艾滋病相关机会性感染 诊断或无法获得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 有效的治疗方法。隐孢子虫被称为“微创” 粘膜病原体和上皮抗菌防御是粘膜先天性抗隐孢子虫的关键 免疫力然而，充分认识到II型干扰素-γ（IFN-γ）是预防癌症所必需的。 肠道隐孢子虫病的发展，最近的进展表明，显着的I型干扰素反应 (e.g., IFN-α和IFN-β）在宿主上皮中诱导。细小病毒感染分子 I型IFN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是 不清楚 微小隐孢子虫病毒1 CSpV 1是部分病毒科Crystovirus属的成员 感染C.和其它隐孢子虫属（Cryptosporidium spp.）我们最近的研究表明， 宿主-寄生虫界面处的CSpV 1-RNA可以在宿主细胞中触发I型IFN应答。C.细小病毒感染 减弱肠上皮细胞对IFN-γ刺激的应答（即，受感染的细胞对 通过IFN-γ活化）。令人惊讶的是，在肠上皮细胞中敲除I型IFN信号传导或抑制I型IFN信号传导可以抑制肠上皮细胞中的IFN信号传导。 CSpV 1-RNA递送可恢复细胞对IFN-γ刺激的应答并促进对C. parvum 感染，表明I型IFN信号传导对上皮抗隐孢子虫防御的负面影响。 基于这些观察结果，我们假设隐孢子虫感染触发I型干扰素反应， 肠上皮细胞和减弱IFN-γ介导的上皮抗菌防御通过传递CSpV 1- RNA。我们将使用体外，离体和体内感染模型和互补的生化，分子， 和形态学方法来阐明隐孢子虫感染的分子机制 在肠上皮中触发I型IFN基因转录（Aim 1），确定隐孢子虫如何 感染调节受感染肠上皮细胞中的JAK/STAT信号传导（目的2），并定义其影响 隐孢子虫诱导的JAK/STAT信号转导失调对上皮抗寄生虫防御的影响（目的3）。的 该提案在概念上是创新的，因为它测试了共生CSpV 1在疾病发病机制中的新机制。 隐孢子虫病，并有可能告知新的治疗策略的未来发展。

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.