Bacterial translocation to mesenteric adipose tissue drives pathogenic stromal-B cell interactions leading to inflammatory IgG

细菌易位至肠系膜脂肪组织驱动致病性基质 B 细胞相互作用，导致炎症 IgG

• 批准号: 10593509
• 负责人: Emilie Kristina Grasset
• 金额: $ 25.43万
• 依托单位: WEILL MEDICAL COLL OF CORNELL UNIV
• 依托单位国家: 美国
• 财政年份: 2023
• 资助国家: 美国
• 起止时间: 2023-02-03 至 2025-01-31
• 项目状态: 未结题
• 来源: https://reporter.nih.gov/project-details/10593509
• 关键词: Adipocytes; Adipose tissue; Affect; Antibodies; Antigen Receptors; Antigens; Automobile Driving; B-Cell Activation; B-Lymphocytes; Bacteria; Bacterial Antigens; Bacterial Translocation; Biopsy; Cell Communication; Cell physiology; Cells; Chronic; Collection; Crohn' s disease; Data; Development; Diagnosis; Disease; Etiology; Excision; Fatty acid glycerol esters; Flow Cytometry; Genes; Genetic Transcription; Germ-Free; Gnotobiotic; Gut Mucosa; Human; IgA Deficiency; Immune system; Immunoglobulin Class Switching; Immunoglobulin G; Immunoglobulin M; Immunology; Impairment; Inflammation; Inflammatory; Inflammatory Bowel Diseases; Intestines; Lead; Left; Leptin; Ligation; Lymphoid; Mesentery; Microbe; Modeling; Mucous Membrane; Mus; Operative Surgical Procedures; Pathogenicity; Pathologic; Pathology; Patients; Phenotype; Plasma Cells; Production; Proliferating; Property; Proteins; Serum; Signal Transduction; Stromal Cells; Tissue Expansion; Tissues; Toll-like receptors; adipokines; antimicrobial; comparison control; cytokine; disease diagnosis; genetic signature; gut inflammation; in vivo; microbiota; murine colitis; new therapeutic target; reconstitution; recruit; response; therapeutic target; transcriptome sequencing

Project Summary Anti-microbial antibodies are predictive of Crohn’s disease (CD) diagnosis and are present in patients’ serum up to 5 years before diagnosis, and their accumulation is associated with complications, often requiring bowel resection surgery. In patients with CD, more bacteria translocate to the mesenteric adipose tissue (MAT) compared to controls and a subset of bacteria are exclusive to CD MAT. This coincides with the expansion of the MAT and its wrapping around the intestine, or “creeping fat”, a hallmark of inflamed CD-affected tissue, which also correlates with complications. The etiology of anti-microbial antibodies and creeping fat are unknown. Although B cells and stromal cells co-localize within fat-associated lymphoid clusters in creeping fat, and B and plasma cell signatures are among the most highly upregulated genes in creeping fat compared to healthy MAT, B cell function in this tissue is unknown. We hypothesize that the translocation of microbes to MAT prompts stromal cells in fat-associated lymphoid clusters to recruit B cells, which differentiate into protective IgM-secreting plasma cells, inhibiting systemic dissemination of bacterial antigens. Sustained CD-specific bacterial translocation to the MAT leads to chronic inflammation activating stromal cells to secrete cytokines driving IgG class-switch and differentiation to inflammatory anti-microbial IgG-secreting plasma cells. Adipocyte-derived leptin is elevated in MAT of CD patients and drives inflammation in mouse colitis models. As leptin activates B cells, we posit leptin further drives preferential class-switch to IgG. We will address this hypothesis in germfree mice reconstituted with cultured collections of bacteria isolated from CD or healthy donors, as well as in human MAT associated or not with inflamed intestine from patients with CD undergoing bowel resection surgery at Mount Sinai. In these models, we will evaluate which bacteria translocate to the MAT, how they activate stromal cells by deep characterization at the transcriptional and protein level and how they drive leptin production by adipocytes in biopsy cultures (Aim 1). Next, we will investigate direct and indirect effects of CD microbiota on MAT B cells and their shift from protective IgM to inflammatory IgG. To do so we will characterize CD microbiota- driven changes in B cell activation, proliferation, class-switching and differentiation to plasma cells. We will also determine the IgG-inducing properties of MAT and stromal cells exposed in vivo to CD or healthy donor microbiota. Finally, we will investigate how CD microbiota perturbs stromal-B cell cross-talk within fat-associated lymphoid clusters (Aim 2). By showing that MAT is able to mount microbiota-specific B cell responses, this proposal will expand the study of mucosal immunology to mucosa-associated adipose tissues. Since creeping fat and anti-microbial IgG correlate with complications in CD, these studies have the potential to uncover mechanisms underlying CD pathology and identify needed therapeutic targets.

项目概要 抗微生物抗体可预测克罗恩病 (CD) 的诊断，并且存在于患者的血清中 诊断前 5 年内，它们的积累与并发症相关，通常需要肠道 切除手术。在 CD 患者中，更多细菌转移至肠系膜脂肪组织 (MAT) 与对照相比，CD MAT 独有细菌子集。这与扩展 MAT 及其围绕肠道的包裹，或“蠕动脂肪”，这是受 CD 影响的发炎组织的标志， 也与并发症相关。抗微生物抗体和蠕动脂肪的病因尚不清楚。 尽管 B 细胞和基质细胞共定位于蠕动脂肪中与脂肪相关的淋巴簇内，并且 B 和 与健康的 MAT 相比，浆细胞特征是蠕变脂肪中上调程度最高的基因之一， 该组织中的 B 细胞功能尚不清楚。我们假设微生物易位至 MAT 提示 脂肪相关淋巴簇中的基质细胞招募 B 细胞，分化为分泌保护性 IgM 的细胞 浆细胞，抑制细菌抗原的全身传播。持续CD特异性细菌 易位至 MAT 导致慢性炎症，激活基质细胞分泌驱动 IgG 的细胞因子 类别转换并分化为分泌炎症抗微生物 IgG 的浆细胞。脂肪细胞来源 瘦素在 CD 患者的 MAT 中升高，并导致小鼠结肠炎模型中的炎症。当瘦素激活 B 细胞中，我们假设瘦素进一步驱动优先类别转换为 IgG。我们将在无菌条件下解决这个假设 用从 CD 或健康供体以及人类中分离的细菌培养物进行重组的小鼠 MAT 与接受肠切除手术的 CD 患者肠道炎症相关或无关 西奈山。在这些模型中，我们将评估哪些细菌易位到 MAT，它们如何激活基质 通过转录和蛋白质水平的深入表征以及它们如何通过以下方式驱动瘦素产生 活检培养物中的脂肪细胞（目标 1）。接下来，我们将研究 CD 微生物群对 CD 的直接和间接影响 MAT B 细胞及其从保护性 IgM 向炎性 IgG 的转变。为此，我们将描述 CD 微生物群的特征 驱动 B 细胞活化、增殖、类别转换和分化为浆细胞的变化。我们还将 确定体内暴露于 CD 或健康供体的 MAT 和基质细胞的 IgG 诱导特性 微生物群。最后，我们将研究 CD 微生物群如何干扰脂肪相关细胞内的基质 B 细胞串扰 淋巴簇（目标 2）。通过证明 MAT 能够引发微生物群特异性 B 细胞反应， 该提案将把粘膜免疫学的研究扩展到粘膜相关的脂肪组织。自从蠕动 脂肪和抗微生物 IgG 与 CD 并发症相关，这些研究有可能揭示 CD 病理学的潜在机制并确定所需的治疗靶点。