Molecular analysis of the immune-modulatory properties of colitogenic intestinal microbiota

Batf3（碱性白细胞拉链转录因子，atf样3）缺陷小鼠允许研究评估相关CD8alpha阳性和CD103阳性CD11b阴性树突状细胞（dc）在体内的特定作用。我们的研究明确地揭示了Batf3在T细胞转移介导的结肠炎中具有保护作用，但在葡聚糖硫酸钠（DSS）诱导和抗cd40介导的结肠炎模型中没有。共房实验表明，转移性结肠炎易感性的增强可传播给表达batf3的野生型小鼠，甚至可传播给Rag1-/- IRF4（干扰素调节因子4）-/-小鼠，而这些小鼠通常对结肠炎诱导不敏感。此外，通常缺乏促进结肠炎能力的il - 23r缺陷t细胞在存在batt3缺乏相关微生物群的情况下诱导结肠炎，这表明batt3缺乏小鼠肠道微生物群在促进结肠炎中起主导作用。最后，通过16s核糖体RNA基因测序分析，正式证实了batf3缺陷小鼠中存在可传递的生态失调。总之，batf3依赖性dc似乎是肠道微生物群的关键调节因子，对结肠炎的易感性和表型具有巨大的影响。根据我们的数据，我们提出了以下模型。batf3依赖性dc的缺失可能会促进肠道微生物群中所谓病原体的发生，从而驱动T细胞和骨髓细胞的扩张。具体来说，我们假设这些群落直接或间接地（例如，通过抑制来自其他共生体的保护性信号）提供以免疫刺激方式起作用的信号，从而产生促进有害免疫介导的结肠炎形成的免疫微环境。因此，拟议研究的中心是鉴定促进结肠炎的微生物群落，它们所使用的分子信号系统，鉴定和表征宿主来源的微生物信号接收机制，以及在存在Batf3缺乏相关肠道微生物群的情况下介导有害结肠炎表现的细胞和分子免疫效应机制。

Batf3 (Basic leucin zipper transcription factor, ATF-like 3) -deficient mice allow studies to assess the specific role of related CD8alpha positive and CD103 positive CD11b negative dendritic cells (DCs) in vivo. Our studies unambiguously revealed a colitis-protective role of Batf3 in the T cell transfer-mediated but not in the Dextran sodiume sulphate (DSS)-induced and anti-CD40-mediated colitis model. Co-housing experiments demonstrated that enhanced transfer colitis susceptibility was transmittable to Batf3-expressing wild type mice and even to Rag1-/- IRF4 (interferon regulatory factor 4)-/- mice usually per se refractory to colitis induction. Also, IL-23R-deficient Tcells normally devoid of colitis-promoting abilities induced colitis in the presence of Batf3-deificiency associated microbiota collectively indicating a dominant functional role of the intestinal microbiota within Batf3-deficient mice in promoting colitis. Finally, the existence of a transmittable dysbiosis in Batf3-deficient mice was formally confirmed by 16s ribosomal RNA gene sequencing analyses. Together, Batf3-dependent DCs appear to be crucial regulators of the intestinal microbiota with tremendous implications for colitis susceptibility and phenotype.Based on our data, we propose the follwoing model. The absence of Batf3-dependent DCs presumably promotes the occurrence of so called pathobionts within the intestinal microbiota that drive T cell and myeloid cell expansion. Specifically, we hypothesize that these communities provide either directly or indirectly (e.g. by inhibiting protective signals derived from other commensals) signals that act in an immune-stimulatory fashion creating an immunological microenvironment that promotes detrimental immune-mediated colitis formation. In the center of the proposed studies is therefore the identification of the colitis-promoting microbial communities, their employed molecular signaling armamentarium, the identification and characterization of the host-derived, microbial signal-receiving machinery and of the cellular and molecular immunological effector mechanisms mediating the detrimental colitis manifestation in the presence of Batf3 deficiency-associated intestinal microbiota.