The pathogenic roles of GSDMD-dependent gut epithelium extracellular vesicles in IBD

摘要 了解环境因素如何触发失调的免疫反应被确定为关键 炎症性肠病（IBD）发病机制的临床前研究面临挑战。失调 肠上皮细胞（IEC）对管腔环境的反应已被广泛认为是一种 IBD的驱动程序另一方面，免疫调节生物制剂的成功，如Vedolizumab和 乌司奴单抗清楚地证明了T细胞，特别是致病性T细胞在IBD中的中心作用。但 目前尚不清楚IEC如何将粘膜表面的先天免疫检测传递给适应性免疫应答 以及随后的炎症。在这种感觉功能的中心出现的是炎性小体，它可以 检测细胞应激和危险信号，如ATP，在慢性炎症期间发现于受损组织。在 为了了解炎性小体在IEC中的作用，我们发现IEC释放大量的 小细胞外囊泡（sEV）含有多泛素化的IL-1家族细胞因子，包括IL-1和IL-18， 以GSDMD依赖性方式对炎性小体活化的反应。重要的是，IEC衍生的sEV代表 这是IEC和T细胞之间的一种新的交流形式。特别地，IL-18促进炎性致病性 通过诱导IFNg和GM-CSF的产生来诱导T细胞。来源于发炎小鼠结肠的sEV加剧 疾病并赋予对抗TNF治疗的抗性。一致，IEC从 IBD患者的炎症区域的活检显示出产生sEV的能力增强， 从非炎症区域。因此，我们假设IEC衍生的sEV在IBD发病机制中起关键作用， 通过增强上皮炎症反应并通过释放sEV促进致病性T细胞 含有IL-1家族细胞因子，包括IL-1和IL-18，可能还有IL-33。本申请旨在确定 作为sEV释放基础的分子机制，并评估sEV在促进 在结肠炎小鼠模型和结肠炎患者来源的标本中， IBD患者

Abstract Understanding how environmental factors trigger dysregulated immune responses was identified as a key challenge in preclinical research for the pathogenesis of inflammatory bowel disease (IBD). Dysregulated responses to the luminal environment by intestinal epithelial cells (IECs) have been widely postulated to be a driver of IBD. On the other hand, the success of immunomodulatory biologics, such as vedolizumab and ustekinumab, clearly demonstrate the central role of T cells, especially pathogenic T cells, in IBD. However, it remains unclear how IECs convey innate immune detection at mucosal surfaces to adaptive immune responses and subsequent inflammation. Emerging at the center of this sensing function is the inflammasome, which can detect cellular stress and danger signals, such as ATP, found in injured tissues during chronic inflammation. In our quest to understand the role of the inflammasome in IECs, we found that IECs release large amounts of small extracellular vesicles (sEVs) containing polyubiquitinated IL-1 family cytokines, including IL-1 and IL-18, in response to inflammasome activation in a GSDMD-dependent manner. Importantly, IEC-derived sEVs represent a novel form of communication between IECs and T cells. In particular, IL-18 promotes inflammatory pathogenic T cells via induction of IFNg and GM-CSF production. sEVs-derived from inflamed mouse colons exacerbate disease and confer resistance to anti-TNF treatment in a T cell transfer colitis model. Consistently, IECs from biopsies of inflamed areas from IBD patients displayed enhanced capacity to produce sEVs compared to that from non-inflamed areas. Thus, we hypothesize that IEC-derived sEVs play a critical role in IBD pathogenesis by amplifying epithelial inflammatory responses and promoting pathogenic T cells via the release of sEVs containing IL-1 family cytokines, including IL-1 and IL-18, and perhaps IL-33. This application seeks to determine the molecular mechanism(s) that underlie the release of sEVs and assess the importance of sEVs in promoting pathogenic T cells and anti-TNF therapy failure in murine models of colitis and in patient-derived specimens from IBD patients.