Department of Inflammation and Immunity, Cleveland Clinic, Lerner Research Institute, Cleveland, Ohio, USA.
Department of Immunology, Faculty of Biochemistry, Biophysics, and Biotechnology, Jagiellonian University, Krakow, Poland.
J Clin Invest. 2020 Aug 3;130(8):4218-4234. doi: 10.1172/JCI138103.
Gasdermin D (GSDMD) induces pyroptosis via the pore-forming activity of its N-terminal domain, cleaved by activated caspases associated with the release of IL-1β. Here, we report a nonpyroptotic role of full-length GSDMD in guiding the release of IL-1β-containing small extracellular vesicles (sEVs) from intestinal epithelial cells (IECs). In response to caspase-8 inflammasome activation, GSDMD, chaperoned by Cdc37/Hsp90, recruits the E3 ligase, NEDD4, to catalyze polyubiquitination of pro-IL-1β, serving as a signal for cargo loading into secretory vesicles. GSDMD and IL-1β colocalize with the exosome markers CD63 and ALIX intracellularly, and GSDMD and NEDD4 are required for release of CD63+ sEVs containing IL-1β, GSDMD, NEDD4, and caspase-8. Importantly, increased expression of epithelial-derived GSDMD is observed both in patients with inflammatory bowel disease (IBD) and those with experimental colitis. While GSDMD-dependent release of IL-1β-containing sEVs is detected in cultured colonic explants from colitic mice, GSDMD deficiency substantially attenuates disease severity, implicating GSDMD-mediated release of IL-1β sEVs in the pathogenesis of intestinal inflammation, such as that observed in IBD.
Gasdermin D(GSDMD)通过其被与白细胞介素 1β(IL-1β)释放相关的激活半胱天冬酶切割的 N 端结构域的孔形成活性诱导细胞焦亡。在此,我们报告全长 GSDMD 在指导肠上皮细胞(IEC)中包含 IL-1β 的小细胞外囊泡(sEV)释放的非细胞焦亡作用。在 caspase-8 炎性体激活后,GSDMD 在 Cdc37/Hsp90 辅助下招募 E3 连接酶 NEDD4,以催化 pro-IL-1β 的多泛素化,作为货物装载到分泌囊泡中的信号。GSDMD 和 IL-1β 在细胞内与外泌体标志物 CD63 和 ALIX 共定位,并且 GSDMD 和 NEDD4 是释放含有 IL-1β、GSDMD、NEDD4 和 caspase-8 的 CD63+sEV 所必需的。重要的是,在炎症性肠病(IBD)患者和实验性结肠炎患者中均观察到上皮衍生的 GSDMD 的表达增加。虽然在结肠炎小鼠的培养结肠外植体中检测到 GSDMD 依赖性释放含 IL-1β 的 sEV,但 GSDMD 缺陷可显著减轻疾病严重程度,表明 GSDMD 介导的 IL-1β sEV 释放参与了肠道炎症的发病机制,如 IBD 中观察到的那样。