Calcium Receptor Action in Childhood Diarrhea

儿童腹泻中钙受体的作用

• 批准号: 8679694
• 负责人: Sam X Cheng
• 金额: $ 12.19万
• 依托单位: UNIVERSITY OF FLORIDA
• 依托单位国家: 美国
• 财政年份: 2014
• 资助国家: 美国
• 起止时间: 2014-04-10 至 2019-03-31
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/8679694
• 关键词: Abbreviations; Acute; Address; Amino Acids; Antidiarrheals; Bicarbonates; Calcium; Calcium-Sensing Receptors; Cell Surface Receptors; Child; Child health care; Childhood; Cholera Toxin; Clinical; Coupled; Cyclic AMP; Cyclic GMP; Cyclophosphamide; Data; Dehydration; Development; Development Plans; Diarrhea; Disease; Doctor of Philosophy; Electrolytes; Enteral; Enteric Nervous System; Enterotoxins; Epithelial; Epithelium; Escherichia coli; Event; Faculty; Florida; Fluids and Secretions; Foundations; GTP-Binding Proteins; Gastroenterology; Immune; In Vitro; Infant; Infection; Institutes; Intestinal Motility; Intestines; Ion Transport; Ions; Isotopes; Knockout Mice; Lead; Ligands; Liquid substance; Measurement; Mediating; Mediator of activation protein; Mentors; Metabolic acidosis; Modeling; Movement; Mus; Muscle; Myenteric Plexus; Nerve; Neurons; Norovirus; Nutrient; Oral; Patients; Peptides; Physiological; Physiology; Polyamines; Positioning Attribute; Process; Property; Receptor Activation; Rehydration Solutions; Research; Research Personnel; Rotavirus; Safety; Severities; Small Intestines; Stomach; Submucous Plexus; Surface; System; Techniques; Testing; Therapeutic; Time; Tissues; Titrations; Toxin; Transport Process; Universities; Vaccination; Viral; Volatile Fatty Acids; Wild Type Mouse; Work; absorption; base; career development; cell motility; detection of nutrient; extracellular; gastrointestinal epithelium; heat stable toxin (E coli); improved; in vivo; in vivo Model; inhibitor/antagonist; insight; interest; novel; novel therapeutic intervention; nutrition; pediatric department; post-doctoral training; professor; protein structure; public health relevance; receptor; solute

DESCRIPTION (provided by applicant): This application outlines a career development plan for me to become an independent investigator researching novel antidiarrheal mechanisms and therapeutic approaches for diarrhea in children. I am now in my first faculty position as an Assistant Professor of Pediatric Gastroenterology in the Department of Pediatrics at the University of Florida. I have a strong background in fluid, electrolyte and nutrition physiology, having received a Ph.D. in ion transport physiology at Karolinska Institute and postdoctoral training in GI physiology under the late Dr. Steven Hebert at Yale University, where I initiated my interest in the calcium/nutrient-sensing receptor (CaSR) in the gut. I am now working with my mentor, Dr. Mansour Mohamadzadeh, studying the unique antidiarrheal function of this nutrient sensing receptor. Acute infectious diarrhea is a worldwide problem, especially among infants, young children and immune-compromised patients. Sadly, 1.3 million children die each year, not because of the infections causing diarrhea, but due to the associated dehydration. The pro-absorptive Oral Rehydration Solution (ORS) is the only recommended oral therapy for children with acute diarrhea, yet it neither reduces diarrhea/secretion nor alters the overly activ enteric nerve (ENS) activity/motility - both significant contributors to diarrhea. The overarching question of this application is the following: can we develop a novel anti-diarrheal therapy that i as simple and has both pro-absorptive and anti-secretory properties while reducing ENS activity and motility? Based upon preliminary data, I hypothesize that the intestinal CaSR is a likely candidate for developing such a therapeutic. The preliminary data show that CaSR is expressed in the gut epithelium, both in the absorbing surface epithelium and secreting crypts. Also, CaSR is densely present in the ENS, both in the fluid-modulating submucosal plexus and the motility-modulating myenteric plexus. Furthermore, using isolated microperfused crypts, it was observed that activating the epithelial CaSR reversed enterotoxin-induced fluid movement from net secretion to net absorption. To test the hypothesis, the following specific aims have been developed: Aim 1: will define the ion transport mechanisms influenced by epithelial CaSR. These studies will be performed in ex vivo intestinal segments using classical physiological techniques that involve the use of Ussing chamber, pH stat titration and measurement of isotope fluxes. Aim 2: will describe influences on gut motility by neuronal CaSR by examining CaSR modulations of evoked contractions in intestinal muscle strips in vitro and gastro-intestinal transit in vivo. Lastly, Aim 3: will assess CaSR anti-diarrheal effect in vivo by examining CaSR effects in (a) enterotoxin (cholera toxin, E coli STa & Rotavirus NSP4)- and (b) Norovirus- induced diarrhea. It is anticipated that this project will yield new insights into intestinal physiology and may lead to the development of novel CaSR-based therapeutics for acute diarrhea. Abbreviations: Ca2+i, intracellular Ca2+; Ca2+o, extracellular Ca2+; CaSR, Ca2+-sensing receptor; CTX, cholera toxin; ENS, enteric nervous system; i.v., intravenously; i.p., intraperitoneally; NSP4, rotavirus non structure protein 4 enterotoxin; ORS, oral rehydration solution; p.o., per os; SCFA, short-chain fatty acids, STa, E. coli heat stable enterotoxin;

描述（由申请人提供）：本申请概述了我的职业发展计划，旨在成为一名独立研究者，研究儿童腹泻的新型止泻机制和治疗方法。我现在的第一个教职是佛罗里达大学儿科系儿科胃肠病学助理教授。我在液体、电解质和营养生理学方面拥有深厚的背景，并获得了博士学位。在卡罗林斯卡学院获得离子运输生理学博士学位，并在耶鲁大学已故史蒂文·赫伯特博士的指导下接受胃肠道生理学博士后培训，在那里我开始对肠道中的钙/营养感应受体 (CaSR) 产生兴趣。我现在正在与我的导师 Mansour Mohamadzadeh 博士合作，研究这种营养感应受体独特的止泻功能。 急性感染性腹泻是一个世界性问题，特别是在婴儿、幼儿和免疫功能低下的患者中。可悲的是，每年有 130 万儿童死亡，不是因为感染引起腹泻，而是因为相关的脱水。促吸收口服补液 (ORS) 是唯一推荐用于治疗急性腹泻儿童的口服疗法，但它既不能减少腹泻/分泌，也不能改变过度活跃的肠神经 (ENS) 活动/运动，而这两者都是导致腹泻的重要因素。该申请的首要问题如下：我们能否开发出一种既简单又具有促吸收和抗分泌特性，同时降低 ENS 活性和运动性的新型抗腹泻疗法？根据初步数据，我推测肠道 CaSR 可能是开发这种疗法的候选者。初步数据显示，CaSR在肠道上皮中表达，包括吸收表面上皮和分泌隐窝。此外，CaSR 密集存在于 ENS 中，无论是在流体调节粘膜下神经丛还是在运动调节肌间神经丛中。此外，使用分离的微灌注隐窝，观察到激活上皮 CaSR 可逆转肠毒素诱导的液体从净分泌到净吸收的运动。为了检验这一假设，制定了以下具体目标： 目标 1：将定义受上皮 CaSR 影响的离子转运机制。这些研究将使用经典生理技术在离体肠段中进行，包括使用尤斯室、pH 统计滴定和同位素通量测量。目标 2：将通过检查体外肠肌条诱发收缩的 CaSR 调节和体内胃肠转运来描述神经元 CaSR 对肠道运动的影响。最后，目标 3：将通过检查 CaSR 在 (a) 肠毒素（霍乱毒素、大肠杆菌 STa 和轮状病毒 NSP4）和 (b) 诺如病毒引起的腹泻中的作用来评估 CaSR 体内抗腹泻作用。预计该项目将对肠道生理学产生新的见解，并可能导致基于 CaSR 的新型急性腹泻疗法的开发。缩写：Ca2+i，细胞内Ca2+； Ca2+o，细胞外Ca2+； CaSR，Ca2+感应受体； CTX，霍乱毒素； ENS，肠神经系统； i.v. 静脉注射； i.p.，腹膜内； NSP4，轮状病毒非结构蛋白4肠毒素； ORS，口服补液； p.o.，按操作系统； SCFA、短链脂肪酸、STa、大肠杆菌热稳定肠毒素；