Harnessing the microbiome to benefit human health requires an initial step in determining the identity and function of causative microorganisms that affect specific host physiological functions. We show a functional screen of the bacterial microbiota from mice with low intestinal immunoglobulin A (IgA) levels; we identified a Gram-negative bacterium, proposed as Tomasiella immunophila , that induces and degrades IgA in the mouse intestine. Mice harboring T. immunophila are susceptible to infections and show poor mucosal repair. T. immunophila is auxotrophic for the bacterial cell wall amino sugar N-acetylmuramic acid. It delivers immunoglobulin-degrading proteases into outer membrane vesicles that preferentially degrade rodent antibodies with kappa but not lambda light chains. This work indicates a role for symbionts in immunodeficiency, which might be applicable to human disease.

中文翻译：

---

适应宿主的营养缺陷型肠道共生体诱导粘膜免疫缺陷


利用微生物组造福人类健康需要首先确定影响特定宿主生理功能的致病微生物的身份和功能。我们对肠道免疫球蛋白 A (IgA) 水平较低的小鼠的细菌微生物群进行了功能筛选；我们鉴定出一种革兰氏阴性细菌，被称为嗜免疫托马西菌（Tomasiellaimmunophila），它能在小鼠肠道中诱导并降解 IgA。携带嗜免疫毛虫的小鼠容易受到感染，并且粘膜修复能力较差。嗜免疫毛虫对细菌细胞壁氨基糖N-乙酰胞壁酸是营养缺陷型的。它将免疫球蛋白降解蛋白酶递送到外膜囊泡中，优先降解带有 kappa 轻链而不是 lambda 轻链的啮齿动物抗体。这项工作表明了共生体在免疫缺陷中的作用，这可能适用于人类疾病。