State Key Laboratory of Veterinary Biotechnology, Harbin Veterinary Research Institutegrid.38587.31, Chinese Academy of Agricultural Sciences, Harbin, China.
College of Veterinary Medicine, Northeast Agricultural University, Harbin, China.
mBio. 2021 Feb 22;13(1):e0360021. doi: 10.1128/mbio.03600-21. Epub 2022 Feb 1.
Pyroptosis, a programmed cell death, functions as an innate immune effector mechanism and plays a crucial role against microbial invasion. Gasdermin D (GSDMD), as the main pyroptosis effector, mediates pyroptosis and promotes releasing proinflammatory molecules into the extracellular environment through pore-forming activity, modifying inflammation and immune responses. While the substantial importance of GSDMD in microbial infection and cancer has been widely investigated, the role of GSDMD in virus infection, including coronaviruses, remains unclear. Enteric coronavirus transmissible gastroenteritis virus (TGEV) and porcine deltacoronavirus (PDCoV) are the major agents for lethal watery diarrhea in neonatal pigs and pose the potential for spillover from pigs to humans. In this study, we found that alphacoronavirus TGEV upregulated and activated GSDMD, resulting in pyroptosis after infection. Furthermore, the fragment of swine GSDMD from amino acids 242 to 279 (242-279 fragment) was required to induce pyroptosis. Notably, GSDMD strongly inhibited both TGEV and PDCoV infection. Mechanistically, the antiviral activity of GSDMD was mediated through promoting the nonclassical release of antiviral beta interferon (IFN-β) and then enhancing the interferon-stimulated gene (ISG) responses. These findings showed that GSDMD dampens coronavirus infection by an uncovered GSDMD-mediated IFN secretion, which may present a novel target of coronavirus antiviral therapeutics. Coronaviruses, primarily targeting respiratory and gastrointestinal epithelia , have a serious impact on humans and animals. GSDMD, a main executioner of pyroptosis, is highly expressed in epithelial cells and involves viral infection pathogenesis. While the functions and importance of GSDMD as a critical regulator of inflammasome activities in response to intracellular bacterial infection have been extensively investigated, the roles of GSDMD during coronavirus infection remain unclear. We here show that alphacoronavirus TGEV triggered pyroptosis and upregulated GSDMD expression, while GSDMD broadly suppressed the infection of enteric coronavirus TGEV and PDCoV by its pore-forming activity via promoting unconventional release of IFN-β. Our study highlights the importance of GSDMD as a regulator of innate immunity and may open new avenues for treating coronavirus infection.
细胞焦亡作为一种程序性细胞死亡方式，是天然免疫的效应机制之一，在抵抗微生物入侵方面发挥着至关重要的作用。Gasdermin D（GSDMD）作为主要的细胞焦亡效应蛋白，通过形成孔道的活性介导细胞焦亡，并促进促炎分子向细胞外环境释放，从而调节炎症和免疫反应。虽然 GSDMD 在微生物感染和癌症中的重要作用已得到广泛研究，但 GSDMD 在病毒感染（包括冠状病毒）中的作用尚不清楚。肠冠状病毒传染性胃肠炎病毒（TGEV）和猪德尔塔冠状病毒（PDCoV）是导致新生仔猪致命性水样腹泻的主要病原体，并有从猪溢出感染人类的潜力。在本研究中，我们发现α冠状病毒 TGEV 感染后上调并激活了 GSDMD，导致细胞焦亡。此外，猪 GSDMD 氨基酸 242 到 279 位的片段（242-279 片段）是诱导细胞焦亡所必需的。值得注意的是，GSDMD 强烈抑制 TGEV 和 PDCoV 的感染。机制上，GSDMD 的抗病毒活性是通过促进非经典释放抗病毒β干扰素（IFN-β），然后增强干扰素刺激基因（ISG）反应介导的。这些发现表明，GSDMD 通过一种未被发现的 GSDMD 介导的 IFN 分泌来抑制冠状病毒感染，这可能为冠状病毒抗病毒治疗提供一个新的靶点。冠状病毒主要靶向呼吸道和胃肠道上皮细胞，对人类和动物健康造成严重影响。GSDMD 作为细胞焦亡的主要执行者，在上皮细胞中高度表达，并参与病毒感染的发病机制。虽然 GSDMD 作为一种关键的调节因子，在细胞内细菌感染时调节炎症小体的活性，其功能和重要性已得到广泛研究，但 GSDMD 在冠状病毒感染过程中的作用仍不清楚。我们在这里表明，α冠状病毒 TGEV 触发了细胞焦亡并上调了 GSDMD 的表达，而 GSDMD 通过其形成孔道的活性广泛抑制了肠冠状病毒 TGEV 和 PDCoV 的感染，这是通过促进 IFN-β 的非常规释放实现的。我们的研究强调了 GSDMD 作为天然免疫调节剂的重要性，并可能为治疗冠状病毒感染开辟新途径。
