Gastrointestinal cell type-specific signaling and C. difficile toxin pathogenesis

胃肠细胞类型特异性信号传导和艰难梭菌毒素发病机制

• 批准号: 10513320
• 负责人: Nicholas O Markham
• 金额: --
• 依托单位: VETERANS HEALTH ADMINISTRATION
• 依托单位国家: 美国
• 财政年份: 2021
• 资助国家: 美国
• 起止时间: 2021-10-01 至 2026-09-30
• 项目状态: 未结题
• 来源: https://reporter.nih.gov/project-details/10513320
• 关键词: Address; Affect; Antibiotic Therapy; Antibodies; Bacterial Infections; CSPG4 gene; Cell Death; Cell Death Induction; Cell Surface Receptors; Cells; Cessation of life; Clinical; Clostridium; Clostridium difficile; Colon; Colon Injury; Communities; Data; Disabled Persons; Disease; Drug resistance; ERBB2 gene; Epidermal Growth Factor Receptor; Epithelial Cells; Epithelium; Exposure to; Family; Genes; Genetic Transcription; Goals; Growth Factor Receptors; Healthcare Systems; Homeostasis; Hospitals; Human; Human Cell Line; Immunofluorescence Immunologic; In Situ; In Vitro; Incidence; Infection; Infection Control; Inflammatory Response; Knowledge; Ligands; Link; Measures; Mediating; Mediator; Microbiology; Modeling; Molecular; Mucous Membrane; Mus; Nosocomial Infections; Oncogenes; Oral; Pathogenesis; Pathogenicity; Pathology; Pathway interactions; Patients; Pharmaceutical Preparations; Phosphorylation; Preventive; Receptor Signaling; Recombinants; Recurrence; Reproduction spores; Resolution; Role; Science; Signal Pathway; Signal Transduction; Small Interfering RNA; Specificity; Standardization; Targeted Toxins; Techniques; Testing; Therapeutic; Tissues; Toxin; Transgenic Mice; Translating; Tyrosine Kinase Inhibitor; Tyrosine Phosphorylation; United States; Veterans; Virulence; Work; antibiotic-associated diarrhea; base; beta catenin; cell behavior; cell injury; cell killing; cell type; chronic infection; colonic crypt; disorder prevention; epidemiologic data; epidemiology study; epithelial stem cell; experimental study; fecal transplantation; fluorophore; gastrointestinal; gastrointestinal epithelium; human disease; in vivo; injury and repair; innovation; knock-down; lentivirally transduced; member; mouse model; mutant; nectin-3; neutralizing antibody; new therapeutic target; novel; novel therapeutics; pharmacologic; prevent; programs; protein expression; receptor; receptor binding; receptor expression; reconstitution; response; self-renewal; small hairpin RNA; small molecule inhibitor; stem; stem cell function; stem cells; success; targeted treatment; therapeutic target; three dimensional cell culture; trend

Nationwide, Clostridioides (formerly Clostridium) difficile infection is the most common cause of antibiotic- associated diarrhea and the most frequent hospital-acquired infection. Recent epidemiological studies have shown an alarming increase in incidence of C. difficile infection in disabled Veterans. Hospital-based infection control programs and careful choice of antibiotic treatments have been beneficial, but recurrent and drug- resistant C. difficile infections persistently burden the VA healthcare system. Therapeutically, fecal microbiota transplant has shown promising success but lacks specificity and standardization. To identify new therapeutic targets or strategies for disease prevention, a better fundamental understanding of how C. difficile toxins damage colonic tissue, and how the human host responds, is essential. Pathogenic strains of C. difficile produce toxin A (TcdA) and/or toxin B (TcdB), which directly kill host cells and induce an inflammatory response in the colonic mucosa. Clinical isolates of C. difficile encoding TcdB alone are sufficient to produce the whole spectrum of pathology in patients with C. difficile infection. Bezlotoxumab is a neutralizing antibody against TcdB and a therapeutic drug for preventing recurrent C. difficile infection. Therefore, TcdB is considered a prominent driver of human disease and will be the specific focus of this proposal. Recently, significant progress has been made to identify host cell surface receptors for TcdB, specifically Nectin- 3, CSPG4, and the Frizzled family of Wnt receptor proteins. The expression of these receptors in human colonic tissue and their respective contribution to TcdB function is not clearly understood. Furthermore, the epithelial cell subtypes targeted by TcdB and how interactions with these cells contribute to pathogenesis during the course of C. difficile infection is understudied. Emerging data suggest TcdB specifically targets the stem and progenitor cells in the base of colonic crypts potentially with the effect of delaying epithelial reconstitution. The Frizzled family of receptors are critical for regulating colonic stem cell function. Additionally, TcdB transactivates the epidermal growth factor receptor (EGFR), a mediator of colonic epithelial cell stem cell behavior. This proposal is based on preliminary data suggesting EGFR, ErbB2, and ErbB3 receptors facilitate TcdB-induced cell death. The effect of TcdB on ErbB signaling has not been studied in vivo, and the impact of this pathway on C. difficile pathogenesis is not known. Given the relevance of ErbB signaling to colonic stem cell behavior in homeostasis and injury repair, it may be that targeting stem or progenitor cells is a critical mechanism of TcdB virulence. The main hypothesis of this proposal is TcdB induces ErbB signaling in colonic stem/progenitor cells as an important component of the pathogenesis of C. difficile infection. The proposed experiments are aimed at using recombinant TcdB and isogenic C. difficile spores with in vivo mouse models and ex vivo human colonoids to understand how TcdB interacts with ErbB receptors in gastrointestinal epithelial cells. The results will determine: (1) the ability of wild type and specific mutant TcdB toxins deficient in receptor binding to alter ErbB pathways in vivo; (2) the impact and mechanism of ErbB inhibition on TcdB-mediated cell death; (3) the specific cell subtypes that are affected during TcdB-mediated colonic injury. The long-term goal of this work is to reveal targets for therapeutic strategies that interdict the pathogenesis of C. difficile infection.

在全国范围内，艰难梭菌（原梭状芽胞杆菌）感染是抗生素最常见的原因