Ceramide membrane microdomains regulate cytokine secretion

神经酰胺膜微结构域调节细胞因子分泌

• 批准号: 8374310
• 负责人: Brij B Singh
• 金额: $ 6.9万
• 依托单位: UNIVERSITY OF NORTH DAKOTA
• 依托单位国家: 美国
• 财政年份: 2012
• 资助国家: 美国
• 起止时间: 2012-05-15 至 2014-04-30
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/8374310
• 关键词: Accounting; Acquired Immunodeficiency Syndrome; Affect; Alveolar; Antibiotic Resistance; Antibiotics; Asthma; Bacteria; Bacterial Infections; Biochemical; Biological Assay; Bronchitis; CCL2 gene; Cell Death; Cell membrane; Cells; Ceramides; Chronic Obstructive Airway Disease; Chronic Sinusitis; Conditioned Culture Media; Cystic Fibrosis; Cytokine Signaling; Data; Development; Disease; Disease Progression; Epithelial; Epithelium; Fatty Acids; Goals; Gram-Negative Bacterial Infections; Health; Homeostasis; Hospital Charges; Host Defense; Host Defense Mechanism; Hydrolysis; Hypersensitivity; Imaging Device; Imaging Techniques; Immune; Immunity; Individual; Infection; Infection Control; Inflammation; Inflammatory; Investigation; Knockout Mice; Laboratories; Link; Lower respiratory tract structure; Lung; Maintenance; Membrane Microdomains; Microbe; Monocyte Chemoattractant Proteins; Mus; Natural Immunity; North Dakota; Onset of illness; Organ; Physiological; Play; Population; Prevention strategy; Process; Production; Progressive Disease; Proteins; Pseudomonas aeruginosa; Recurrence; Regulation; Research; Resistance; Risk; Role; Signal Transduction; Staging; Stem cells; Techniques; Testing; Tuberculosis; Type II Epithelial Receptor Cell; Universities; Work; aged; antimicrobial; base; cell growth; cell type; combat; cystic fibrosis patients; cytokine; effective therapy; imaging modality; immune function; improved; insight; interest; new therapeutic target; novel; novel therapeutics; pathogen; respiratory; spatiotemporal; surfactant; treatment strategy

DESCRIPTION (provided by applicant): Although alveolar epithelial type II cells (AECII) form the barrier of alveolar spaces and produce surfactants to maintain lung integrity, the unique AECII population in the lung may also play a critical role in anti-microbial immunity by secreting cytokines, such as monocyte chemoattractant protein (MCP-1) against P. aeruginosa (PA) infection. However, the mechanism of cytokine secretion is largely unknown. Our long-term goal is to understand mechanisms of lung host defense, thereby identifying new strategies for treating bacterial infection. Our objective of this application is to characterize the mechanism of cytokine secretion by AECII. We hypothesize that AECII play immune roles by secreting cytokines, which is regulated through a mechanism of membrane microdomain reorganization. We have formulated this hypothesis based on our recent studies and two separate lines of evidence. First, in a high purity cell population, we found that a conditioned medium from PA-infected primary AECII enhanced AM immunity. On the other hand, the importance of lipid rafts (membrane microdomains) for innate immunity has been indicated by the fact that CF patients, who are particularly at risk for PA infection, may often suffer from abnormal lipid raft function due to ceramide deficiency and fatty-acid imbalance. Consistent with this, we showed that lipid rafts may be involved in the secretion of the cytokine MCP-1, which is localized in ceramide-rich rafts. Our rationale is that elucidating the relevant mechanism in ceramide-rich microdomains will define a general mechanism for cytokine secretion. Our laboratory is ideally suited for this research since we have the requisite expertise in AECII isolation, PA infection, and advanced biochemical techniques. To test our hypothesis, we propose the following two specific aims: Specific Aim 1: To characterize dynamic reorganization of membrane microdomains in regulating cytokine secretion in AECII and in mice using imaging tools. Our working hypothesis is that PA infection initiates dynamic changes in membrane microdomains that impact cytokine production. Specific Aim 2: To define the mechanism by which membrane microdomains regulate key cytokines required for PA defense. Our hypothesis is that ceramide is generated by hydrolysis and translocated to specialized domains, where it initiates signaling for production of MCP-1. Due to the important role of cytokines in various physiological and pathological conditions, these novel mechanisms will improve understanding of cytokine secretion for other types of cells, pathogens, and inflammatory situations, and thereby identifying new therapeutic targets. PUBLIC HEALTH RELEVANCE: Although alveolar epithelial type II cells (AECII) are structural and progenitor cells in the lung, they also provide immune defense by secreting cytokines. This unique immunity may critically increase host defense against P. aeruginosa (PA), a bacterium that causes severe infections in immunodeficient individuals, such as AIDS, tuberculosis and cystic fibrosis. We hypothesize that AECII secrete cytokines through changes in cell membrane microdomains, a novel mechanism that may impact many disease processes. Thus, our research will provide new insights into the development of novel treatment for this recurrent infection.

描述（由申请方提供）：尽管肺泡上皮II型细胞（AECII）形成肺泡间隙屏障并产生表面活性剂以维持肺完整性，但肺中独特的AECII群体也可能通过分泌细胞因子（如抗铜绿假单胞菌（PA）感染的单核细胞趋化蛋白（MCP-1））在抗微生物免疫中发挥关键作用。然而，细胞因子分泌的机制在很大程度上是未知的。我们的长期目标是了解肺部宿主防御机制，从而确定治疗细菌感染的新策略。本申请的目的是表征 AECII的细胞因子分泌。我们假设AECII通过分泌细胞因子发挥免疫作用，细胞因子通过膜微区重组机制进行调节。我们根据最近的研究和两条独立的证据制定了这一假设。首先，在高纯度的细胞群中，我们发现来自PA感染的原代AECII的条件培养基增强AM免疫。另一方面，脂筏（膜微结构域）对先天免疫的重要性已经由以下事实表明：CF患者，特别是PA感染的风险，可能经常由于神经酰胺缺乏和脂肪酸失衡而遭受异常脂筏功能。与此一致，我们发现，脂筏可能参与分泌的细胞因子MCP-1，这是本地化的神经酰胺丰富的筏。我们的理由是，阐明相关的机制，在富含神经酰胺的微域将定义一个一般的机制，细胞因子分泌。我们的实验室非常适合这项研究，因为我们在AECII分离、PA感染和先进生化技术方面拥有必要的专业知识。为了验证我们的假设，我们提出了以下两个具体目标：具体目标1：为了表征动态重组的膜微区在调节细胞因子分泌AECII和小鼠使用成像工具。我们的工作假设是，PA感染启动动态变化的膜微区，影响细胞因子的产生。具体目标2：确定膜微区调节PA防御所需的关键细胞因子的机制。我们的假设是，神经酰胺是通过水解产生的，并转移到专门的领域，在那里它启动信号产生MCP-1。由于细胞因子在各种生理和病理条件下的重要作用，这些新的机制将提高对其他类型的细胞，病原体和炎症情况下的细胞因子分泌的理解，从而确定新的治疗靶点。 公共卫生相关性：虽然肺泡上皮II型细胞（AECII）是肺中的结构和祖细胞，但它们也通过分泌细胞因子提供免疫防御。这种独特的免疫力可能会极大地增加宿主对铜绿假单胞菌（PA）的防御，PA是一种在免疫缺陷个体中引起严重感染的细菌，如AIDS，结核病和囊性纤维化。我们假设AECII通过细胞膜微区的变化分泌细胞因子，这是一种可能影响许多疾病过程的新机制。因此，我们的研究将为这种复发性感染的新治疗方法的发展提供新的见解。