Department of Biochemistry and Molecular Biology, Cumming School of Medicine, University of Calgary, Calgary, Canada; Department of Microbiology, Immunology and Infectious Diseases, Cumming School of Medicine, University of Calgary, Calgary, Canada; Arnie Charbonneau Cancer Research Institute, Calgary, Canada.
The Walter and Eliza Hall Institute of Medical Research, 1G Royal Parade, Parkville, Victoria, Australia; Department of Medical Biology, University of Melbourne, Parkville, Australia.
Mucosal Immunol. 2024 Jun;17(3):371-386. doi: 10.1016/j.mucimm.2024.03.002. Epub 2024 Mar 16.
Interleukin-(IL) 22 production by intestinal group 3 innate lymphoid cells (ILC3) is critical to maintain gut homeostasis. However, IL-22 needs to be tightly controlled; reduced IL-22 expression is associated with intestinal epithelial barrier defect while its overexpression promotes tumor development. Here, using a single-cell ribonucleic acid sequencing approach, we identified a core set of genes associated with increased IL-22 production by ILC3. Among these genes, programmed cell death 1 (PD-1), extensively studied in the context of cancer and chronic infection, was constitutively expressed on a subset of ILC3. These cells, found in the crypt of the small intestine and colon, displayed superior capacity to produce IL-22. PD-1 expression on ILC3 was dependent on the microbiota and was induced during inflammation in response to IL-23 but, conversely, was reduced in the presence of Notch ligand. PD-1 ILC3 exhibited distinct metabolic activity with increased glycolytic, lipid, and polyamine synthesis associated with augmented proliferation compared with their PD-1 counterparts. Further, PD-1 ILC3 showed increased expression of mitochondrial antioxidant proteins which enable the cells to maintain their levels of reactive oxygen species. Loss of PD-1 signaling in ILC3 led to reduced IL-22 production in a cell-intrinsic manner. During inflammation, PD-1 expression was increased on natural cytotoxicity receptor (NCR) ILC3 while deficiency in PD-1 expression resulted in increased susceptibility to experimental colitis and failure to maintain gut barrier integrity. Collectively, our findings uncover a new function of the PD-1 and highlight the role of PD-1 signaling in the maintenance of gut homeostasis mediated by ILC3 in mice.
肠 3 型固有淋巴细胞(ILC3)产生的白细胞介素(IL)22 对于维持肠道内稳态至关重要。然而,IL-22 需要被严格控制;IL-22 表达减少与肠道上皮屏障缺陷有关,而其过度表达则促进肿瘤发展。在这里,我们使用单细胞 RNA 测序方法,鉴定出一组与 ILC3 产生增加的 IL-22 相关的核心基因。在这些基因中,程序性细胞死亡 1(PD-1)在癌症和慢性感染的背景下被广泛研究,在 ILC3 的一个亚群上持续表达。这些细胞存在于小肠和结肠的隐窝中,具有更高的产生 IL-22 的能力。ILC3 上 PD-1 的表达依赖于微生物群,在炎症期间,IL-23 诱导其表达,但相反,在 Notch 配体存在的情况下,其表达会减少。PD-1 ILC3 表现出独特的代谢活性,与增强的增殖相关的糖酵解、脂质和多胺合成增加,与它们的 PD-1 对应物相比。此外,PD-1 ILC3 表现出增加的线粒体抗氧化蛋白表达,使细胞能够维持其活性氧水平。在 ILC3 中丧失 PD-1 信号导致 IL-22 的产生以细胞内在的方式减少。在炎症期间,自然细胞毒性受体(NCR)ILC3 上 PD-1 的表达增加,而 PD-1 表达减少导致实验性结肠炎易感性增加和肠道屏障完整性丧失。总的来说,我们的研究结果揭示了 PD-1 的新功能,并强调了 PD-1 信号在 ILC3 介导的小鼠肠道内稳态维持中的作用。
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