Cytokine signaling and IEC restitution in enteropathy: the Giardia paradigm

描述(申请人提供)：这是一个申请职业发展奖(K08)的路德·巴特尔，医学博士。巴特尔特博士是弗吉尼亚大学传染病和国际卫生分部的传染病研究员。他的研究是在理查德·L·格雷兰特博士的指导下进行的，他是FIDSA医学博士，托马斯·H·亨特是弗吉尼亚大学医学院传染病和国际卫生方面的国际医学教授。Guerrant博士是美国传染病学会导师奖的获得者，在他的职业生涯中指导了150多名学生和研究员。拟议的项目将在弗吉尼亚大学新建的卡特·哈里森医学科学大楼内执行，该大楼有超过10万平方英尺的净研究空间，并可以使用最先进的动物研究和分子设备设施。 巴特尔特博士的职业生涯是一名内科科学家，专注于导致环境肠病的肠道感染，这是导致儿童营养不良的一种非常常见的原因。他的直接目标是获得关于原生动物普遍存在的原生动物病原体兰布里亚原虫作为生长失败原因的发病机制的专业知识。蓝氏菌感染在高达90%的儿童中发生，在某些人群中与营养不良有关。对兰布里亚革兰氏菌影响的实地调查已达到平衡状态，调查结果表明，对急性腹泻具有保护作用，但增加了持续性腹泻的风险。该项目将利用一种新的C57BL/6小鼠持续性贾第鞭毛虫病模型来研究感染革兰氏原虫后导致生长受损的机制。这项工作建立在Bartelt博士的发现基础上，即C57BL/6菌株在攻击革兰氏菌H3纯化包囊后容易持续感染。这是创新的，因为最近没有其他研究人员发表过贾第虫和营养不良持续相互作用的模型。贾第鞭毛虫感染的小鼠发育受损，这种表型在伴随营养不良的过程中会加速。被检验的假设是，兰氏革兰氏菌损害肠上皮细胞(IEC)的增殖和分化，代偿性适应性宿主黏膜防御是IEC恢复所必需的。初步数据显示，与营养不良的感染对照组相比，营养不良感染的小鼠绒毛变钝，隐窝增殖减少。此外，营养不良的小鼠对感染的组织IL4和IL5反应减弱。总而言之，这些发现导致了假设 在这个新的贾第鞭毛虫病和营养不良的小鼠模型中，无效的肠上皮细胞(IEC)增殖导致生长失败，而与IL4相关的宿主粘膜反应是保护性的。该项目将确定体内早期上皮细胞对蓝氏贾第鞭毛虫H3的反应，在感染早期和已建立的蓝氏菌感染期间上皮室中的诱导信号分子，以及营养不良引起的细胞和粘膜分子异常，并将确定与其他细胞因子介导的途径相比，IL4在早期和已建立的贾第虫病中对IEC增殖的作用。这一发现将促进对兰氏革兰氏菌的发病机制和对促进肠病的肠道病原体的粘膜防御的了解。概述的职业发展计划包括关于免疫学和细胞生物学的研究生水平课程和补充实验室讲习班，这些讲习班将提高这一领域的知识和技术技能。此外，职业发展计划包括教师发展证书课程，与研究项目相结合，将为过渡到独立研究人员和导师奠定坚实的基础。优秀的导师以及良好的支持性环境和良好的记录将提供实验专业知识和科学指导。 相关性：兰氏革兰氏菌是一种全球普遍存在的病原体，与持续性腹泻有关，并与营养不良相一致。这项研究将确定兰氏革兰氏菌导致生长失败的机制。重点将放在促进上皮细胞增殖的宿主粘膜防御系统的作用上。这一结果将有助于改善营养不良儿童和肠道疾病的粘膜修复策略。

DESCRIPTION (provided by applicant): This is an application for a Career Development Award (K08) for Luther Bartelt, MD. Dr. Bartelt is an Infectious Disease Fellow at the University of Virginia in the Division of Infectious Diseases and International Health. His research is being conducted under the mentorship of Dr. Richard L. Guerrant, MD, FIDSA, Thomas H. Hunter Professor of International Medicine in Infectious Diseases and International Health at the University of Virginia School of Medicine. Dr. Guerrant is a recipient of the Infectious Disease Society of America Mentor Award, and has mentored more than 150 students and fellows during his career. The proposed project will be executed at the University of Virginia in the newly constructed Carter Harrison Medical Science Building with more than 100,000 net square feet of research space and access to state of the art facilities for animal research and molecular equipment. Dr. Bartelt is pursuing a career as a physician-scientist focusing on enteric infections that contribute to environmental enteropathy, an exceedingly common cause of childhood malnutrition. His immediate goal is to gain expertise in the pathogenesis of the ubiquitous protozoan pathogen G. lamblia as a cause of growth failure. G. lamblia infection occurs in up to 90% of children and in some populations associates with malnutrition. Field investigations of the impact of G. lamblia have reached a state of equipoise, with findings demonstrating protection from acute diarrhea but increased risk of persistent diarrhea. This project will utiliz a novel C57Bl/6 murine model of persistent giardiasis to investigate mechanisms that lead to impaired growth following G. lamblia infection. This work builds on Dr. Bartelt's discovery that the C57Bl/6 strain is susceptible to persistent infection following challenge with G. lamblia H3 purified cysts. It is innovative, as no other investigators have recently published a model of persistent Giardia and malnutrition interactions. Giardia-infected mice develop impaired growth, a phenotype that is accelerated during concomitant malnutrition. The hypothesis tested is that G. lamblia impairs intestinal epithelial cell (IEC) proliferation and differentiation, and that compensatory adaptive host mucosal defenses are necessary for IEC restitution. Preliminary data shows that malnourished-infected mice have blunted villi and diminished crypt proliferation compared to nourished-infected controls. Furthermore, malnourished mice have diminished tissue IL4 and IL5 responses to infection. Collectively, these findings have led to the hypothesis that in this novel murine model of giardiasis and malnutrition, ineffective intestinal epithelial ell (IEC) proliferation leads to growth failure, and that IL4-related host mucosal responses are protective. This project will define early epithelial cell responses to G. lamblia H3 in vivo, inducer signaling molecules in the epithelial compartment during early and established G. lamblia H3 infection, the cellular and mucosal molecular aberrations caused by malnutrition in response to G. lamblia, and will define the role of IL4 for IEC proliferation during early and established giardiasis as compared to alternative cytokine-mediated pathways. The findings will advance knowledge of G. lamblia pathogenesis and mucosal defenses to enteric pathogens that promote enteropathy in general. The outlined career development plan is inclusive of graduate level courses on immunology and cellular biology and complementary laboratory workshops that will enhance both knowledge and technical skills in this field. Furthermore, the career development plan includes a certificate course in Faculty Development, which in combination with the research project will provide a solid foundation for transition to an independent researcher and mentor. Excellent mentorship along with a supportive environment with a well-proven track record will provide experimental expertise and scientific guidance. RELEVANCE: G. lamblia is a globally ubiquitous pathogen that associates with persistent diarrhea and is syndemic with malnutrition. This research will identify mechanisms whereby G. lamblia induces growth failure. The focus will be on the role of host mucosal defenses that facilitate epithelial cell proliferation. The results will be useful for improving strategies for mucosal repair in malnourished children and enteric diseases in general.