Mechanisms of HIV-associated epithelial intestinal stem cell (ISC) dysfunction

HIV相关上皮肠干细胞（ISC）功能障碍的机制

• 批准号: 10201595
• 负责人: Henrik Kloverpris
• 金额: $ 71.19万
• 依托单位: MASSACHUSETTS GENERAL HOSPITAL
• 依托单位国家: 美国
• 财政年份: 2020
• 资助国家: 美国
• 起止时间: 2020-07-01 至 2025-06-30
• 项目状态: 未结题
• 来源: https://reporter.nih.gov/project-details/10201595
• 关键词: Address; Africa South of the Sahara; Apoptosis; Area; Bacteria; Biological Markers; Biological Models; Biopsy; Biopsy Specimen; Blood; Blood Circulation; CD4 Positive T Lymphocytes; Cell physiology; Cells; Cessation of life; Chronic; Colon; Data; Defect; Development; Disease; Disease Progression; Duodenum; Epithelial; Epithelial Cells; Functional disorder; Gastrointestinal tract structure; Genetic Transcription; HIV; HIV Infections; Health; Heart Diseases; Histology; Homeostasis; Hospitals; Human; Hyperglycemia; Immune; Immune System Diseases; Immunology; Impairment; In Situ; Incidence; Individual; Inflammation; Inflammatory; Inflammatory Bowel Diseases; Injury; Institutes; Intercellular Junctions; Interferons; Interleukin-10; Interleukin-13; Interleukin-17; Intestinal Mucosa; Intestinal permeability; Intestines; Knowledge; MHC Class II Genes; Massachusetts; Mediating; Modeling; Molecular; Morbidity - disease rate; Mucous Membrane; Mus; Organoids; Outcome; Pathogenesis; Pathologist; Pathology; Pathway interactions; Peripheral; Permeability; Phenotype; Population; Positioning Attribute; Prevalence; Process; Production; Regimen; Reporting; Role; Sampling; Signal Pathway; Signal Transduction; Site; South Africa; System; T-Cell Depletion; T-Lymphocyte; Techniques; Technology; Testing; Tissue Sample; Tissues; Viral Load result; Virus Replication; antiretroviral therapy; base; cohort; cytokine; epithelial repair; exhaustion; experience; gastrointestinal; gastrointestinal epithelium; graft vs host disease; gut bacteria; gut dysbiosis; immune activation; improved; in vivo; inflammatory disease of the intestine; interleukin-22; intestinal barrier; intestinal epithelium; microbial; mortality; mouse model; novel therapeutic intervention; protein expression; response; self-renewal; stem cell biology; stem cell differentiation; stem cell function; stem cell proliferation; stem cells; systemic inflammatory response

SUMMARY The gastrointestinal (GI) tract is a major site of Human Immunodeficiency Virus (HIV) replication, which leads to intestinal inflammation, CD4+ T cell depletion and gut epithelial barrier dysfunction. These defects are thought to drive HIV disease progression by allowing translocation of luminal microbial products into the circulation, which triggers chronic systemic immune activation and disease progression. Although antiretroviral therapy (ART) effectively suppress viral replication in the blood, it does not restore CD4+ T cell levels in the gut; even individuals with suppressed viral loads for decades have persistent gut barrier impairment and continued microbial translocation. Epithelial intestinal stem cells (ISCs) are responsible for replenishing the intestinal epithelium during normal homeostatic turnover and orchestrating epithelial repair following injury. Current studies of intestinal epithelial dysfunction in HIV are limited and have relied primarily on correlative observations based on histology or peripheral biomarkers. Our proposal addresses critical gaps in knowledge by 1) performing in-depth characterization of ISC proliferation, self-renewal and differentiation ex vivo and in vivo in HIV-infected and uninfected individuals; 2) utilizing tissue samples from a unique cohort of individuals in sub-Saharan Africa, where HIV burden is highest and most devastating; 3) applying cutting-edge techniques to uncover molecular signalling pathways involved in HIV-induced epithelial dysfunction; and 4) thoroughly testing mechanistic hypotheses using relevant mouse models and ex vivo organoid culture systems. With our combined expertise in HIV disease, mucosal immunology and GI pathology, we are well positioned to uncover specific mechanisms that underlie intestinal epithelial dysfunction in HIV infection. An understanding of these mechanisms is critical to facilitate development of novel therapeutic approaches to improve health outcomes of people living with HIV. In this proposal, we hypothesize that HIV infection results in hyperproliferation of ISCs, aberrant ISC differentiation, increase epithelial death, and dysfunction of epithelial cellular junction integrity. Additionally, based upon our data, we hypothesize that this HIV-associated ISC dysfunction can occur via two mechanisms: 1) depletion of intestinal CD4+ T cells and loss of specific T helper cytokines that promote intestinal epithelial homeostasis and 2) type I and II interferon signalling within ISCs in HIV-infected individuals. To address these hypotheses we are proposing two complementary aims. Aim 1 will use state-of-the-art technologies to characterise ISC function directly ex vivo in gut pinch biopsies sampled throughout the intestinal mucosa from our established cohort at Albert Luthuli Central Hospital in Durban, South Africa. In Aim 2 will use in vivo mouse models of CD4+ T cell depletion and examine the impact on ISC proliferation, self-renewal and differentiation, and use ex vivo human organoid models to study the impact of type I and II interferon pathways on ISC function. This proposal will address important unknown mechanisms of ISC biology that may help in the development of new strategies to reverse gut barrier defects in HIV infection.

概括 胃肠道 (GI) 是人类免疫缺陷病毒 (HIV) 复制的主要场所，这会导致 肠道炎症、CD4+ T 细胞耗竭和肠上皮屏障功能障碍。这些缺陷被认为 通过允许腔内微生物产物转移到循环中来驱动艾滋病毒疾病进展，这 引发慢性全身免疫激活和疾病进展。尽管抗逆转录病毒治疗（ART） 有效抑制血液中的病毒复制，但不会恢复肠道中的CD4+ T细胞水平；甚至个人 几十年来病毒载量受到抑制，肠道屏障持续受损，微生物持续存在 易位。肠上皮干细胞（ISC）负责补充肠上皮 在正常的稳态更新和协调损伤后的上皮修复期间。目前的研究 HIV 中的肠上皮功能障碍是有限的，并且主要依赖于基于 组织学或外周生物标志物。我们的提案通过 1）深入执行来解决知识方面的关键差距 HIV感染者和体内ISC增殖、自我更新和分化的表征 未受感染的个体； 2) 利用来自撒哈拉以南非洲的一组独特个体的组织样本， 艾滋病毒负担最高且最具破坏性的地方； 3）应用尖端技术揭示分子 参与 HIV 诱导的上皮功能障碍的信号通路； 4）彻底测试机制 使用相关小鼠模型和离体类器官培养系统的假设。凭借我们的综合专业知识 HIV疾病、粘膜免疫学和胃肠道病理学，我们有能力揭示具体机制 这是 HIV 感染时肠上皮功能障碍的基础。了解这些机制至关重要 促进新型治疗方法的开发，以改善艾滋病毒感染者的健康结果。 在本提案中，我们假设 HIV 感染导致 ISC 过度增殖，即异常 ISC 分化、增加上皮细胞死亡和上皮细胞连接完整性功能障碍。此外， 根据我们的数据，我们假设这种与 HIV 相关的 ISC 功能障碍可以通过两种机制发生： 1) 肠道 CD4+ T 细胞的消耗和促进肠上皮细胞生长的特异性 T 辅助细胞因子的丧失 体内平衡；2) HIV 感染者 ISC 内的 I 型和 II 型干扰素信号传导。为了解决这些 假设我们提出两个互补的目标。目标 1 将使用最先进的技术 在整个肠粘膜取样的肠道捏取活组织检查中直接离体表征 ISC 功能 我们在南非德班的阿尔伯特卢图利中心医院建立了队列。 《Aim 2》将使用体内鼠标 CD4+ T 细胞耗竭模型并检查对 ISC 增殖、自我更新和分化的影响， 并使用离体人体类器官模型来研究 I 型和 II 型干扰素途径对 ISC 功能的影响。 该提案将解决 ISC 生物学的重要未知机制，可能有助于开发 逆转艾滋病毒感染肠道屏障缺陷的新策略。