Effect of Microbial Metabolites on Growth of Cryptosporidium

总结 隐孢子虫病是一种常见的原因严重，慢性牙周病的免疫功能低下的病人 例如艾滋病毒/艾滋病患者。FDA唯一批准的治疗隐孢子虫病的药物，硝唑尼特， 在免疫功能低下的患者中效果有限。尽管HAART疗法的出现， 隐孢子虫病仍然是HIV诊断或抗病毒药物治疗无效的患者群体中的主要问题。 治疗不够。作为一种肠道病原体，隐孢子虫与复杂的微生物 构成微生物组的群落。对微生物群的干扰，例如通过抗生素 治疗与成年动物对感染的易感性增加有关。此外，新生儿 动物体内的微生物群不成熟，比其他动物更容易感染隐孢子虫。 成年人了微生物群可能影响隐孢子虫感染易感性的一种方法是 通过产生抑制性小分子代谢物。例如，高粪便吲哚水平 在隐孢子虫的人类挑战研究中，总的来说，这些发现 提出了一个有趣的假设，即微生物群产生的代谢物会影响感染的易感性 隐孢子虫在初步研究中，我们筛选了一个细菌代谢物库， 正常成人微生物群的丰富成分，因为它们能够抑制C. parvum in vitro.我们 确定了几类代谢物，它们是寄生虫生长的有效抑制剂，但水平不具有毒性 宿主细胞。拟议的研究将探索这些微生物代谢物的抑制机制 通过确定它们针对寄生虫生命周期的哪个（哪些）阶段以及它们是静止的还是杀灭的。我们将 还探索激活宿主防御的宿主细胞信号通路，作为 这些代谢物起作用。最后，通过使用隐孢子虫病的动物模型，我们将测试是否抑制 代谢物可用于治疗体内感染。如果成功，这些研究可能会建立一个新的范式， 治疗免疫功能低下患者的持续性隐孢子虫病。

Summary Cryptosporidiosis is a common cause of severe, chronic diarrheal disease in immunocompromised patients such as those with HIV/AIDS. The only FDA approved drug for treatment of cryptosporidiosis, nitazoxanide, has limited effectiveness in immunocompromised patients. Despite the advent of HAART therapy, cryptosporidiosis still presents a major problem among patient populations where HIV diagnosis or anti-viral treatments are inadequate. As an enteric pathogen, Cryptosporidium interacts with the complex microbial community that constitutes the microbiome. Perturbations to the microbiota, such as through antibiotic treatment, are associated with increased susceptibility to infection in adult animals. Additionally, neonatal animals, which harbor an immature microbiota, are much more susceptible to Cryptosporidium infection than adults. One method by which the microbiota may influence susceptibility to Cryptosporidium infection is through the production of inhibitory small molecule metabolites. For example, high fecal indole levels were associated with lower susceptibility in a human challenge study of Cryptosporidium. Collectively, these findings raise the intriguing hypothesis that metabolites produced by the microbiota influence susceptibility to infection with Cryptosporidium. In preliminary studies, we have screened a library of bacterial metabolites that are abundant components of the normal adult microbiota for their ability to inhibit growth of C. parvum in vitro. We identified several classes of metabolites that are potent inhibitors of parasite growth at levels that are not toxic to host cells. The proposed studies will explore the mechanism(s) of inhibition by these microbial metabolites by determining which stage(s) of the parasite life cycle they target and whether they are static or cidal. We will also explore host cell signaling pathways that activate host defenses, as the potential mechanism by which these metabolites act. Finally, by employing animal models for cryptosporidiosis, we will test whether inhibitory metabolites can be used to treat infection in vivo. If successful, these studies may establish a new paradigm for treating persistent cryptosporidiosis in immunocompromised patients.