Department of Critical Care Medicine, Ruijin Hospital, Shanghai Jiao Tong University School of Medicine, Shanghai 200025, China.
Department of Critical Care Medicine, Shanghai Children's Hospital, Shanghai Jiao Tong University School of Medicine, Shanghai 200062, China.
Chin Med J (Engl). 2022 Nov 5;135(21):2585-2595. doi: 10.1097/CM9.0000000000002543.
Gut-resident macrophages (gMacs) supplemented by monocytes-to-gMacs differentiation play a critical role in maintaining intestinal homeostasis. Activating transcription factor 4 (ATF4) is involved in immune cell differentiation. We therefore set out to investigate the role of ATF4-regulated monocytes-to-gMacs differentiation in sepsis-induced intestinal injury.
Sepsis was induced in C57BL/6 wild type (WT) mice and Atf4- knockdown ( Atf4+/ - ) mice by cecal ligation and puncture or administration of lipopolysaccharide (LPS). Colon, peripheral blood mononuclear cells, sera, lung, liver, and mesenteric lymph nodes were collected for flow cytometry, hematoxylin and eosin staining, immunohistochemistry, quantitative reverse transcription polymerase chain reaction, and enzyme-linked immunosorbent assay, respectively.
CD64, CD11b, Ly6C, major histocompatibility complex-II (MHC-II), CX3CR1, Ly6G, and SSC were identified as optimal primary markers for detecting the process of monocytes-to-gMacs differentiation in the colon of WT mice. Monocytes-to-gMacs differentiation was impaired in the colon during sepsis and was associated with decreased expression of ATF4 in P1 (Ly6C hi monocytes), the precursor cells of gMacs. Atf4 knockdown exacerbated the impairment of monocytes-to-gMacs differentiation in response to LPS, resulting in a significant reduction of gMacs in the colon. Furthermore, compared with WT mice, Atf4+/- mice exhibited higher pathology scores, increased expression of inflammatory factor genes ( TNF-α, IL-1β ), suppressed expression of CD31 and vascular endothelial-cadherin in the colon, and increased translocation of intestinal bacteria to lymph nodes and lungs following exposure to LPS. However, the aggravation of sepsis-induced intestinal injury resulting from Atf4 knockdown was not caused by the enhanced inflammatory effect of Ly6C hi monocytes and gMacs.
ATF4, as a novel regulator of monocytes-to-gMacs differentiation, plays a critical role in protecting mice against sepsis-induced intestinal injury, suggesting that ATF4 might be a potential therapeutic target for sepsis treatment.
肠道驻留巨噬细胞（gMacs）通过单核细胞向 gMacs 的分化补充，在维持肠道内稳态中发挥关键作用。激活转录因子 4（ATF4）参与免疫细胞分化。因此，我们着手研究 ATF4 调节的单核细胞向 gMacs 分化在脓毒症诱导的肠道损伤中的作用。
通过盲肠结扎和穿孔或脂多糖（LPS）给药，在 C57BL/6 野生型（WT）小鼠和 Atf4 敲低（Atf4+/ -）小鼠中诱导脓毒症。收集结肠、外周血单核细胞、血清、肺、肝和肠系膜淋巴结，分别用于流式细胞术、苏木精和伊红染色、免疫组织化学、定量逆转录聚合酶链反应和酶联免疫吸附试验。
CD64、CD11b、Ly6C、主要组织相容性复合体-II（MHC-II）、CX3CR1、Ly6G 和 SSC 被鉴定为检测 WT 小鼠结肠中单核细胞向 gMacs 分化过程的最佳初始标志物。脓毒症期间，单核细胞向 gMacs 的分化在结肠中受损，与前体细胞 gMacs 中 ATF4 的表达减少有关。Atf4 敲低加剧了 LPS 反应中单核细胞向 gMacs 分化的损伤，导致结肠中 gMacs 明显减少。此外，与 WT 小鼠相比，Atf4+/- 小鼠表现出更高的病理评分、炎症因子基因（TNF-α、IL-1β）表达增加、结肠中 CD31 和血管内皮钙黏蛋白表达受抑制，以及 LPS 暴露后肠道细菌向淋巴结和肺部的易位增加。然而，由于 Ly6C hi 单核细胞和 gMacs 的炎症作用增强，Atf4 敲低导致的脓毒症诱导的肠道损伤加重并非如此。
ATF4 作为单核细胞向 gMacs 分化的新型调节因子，在保护小鼠免受脓毒症诱导的肠道损伤中发挥关键作用，提示 ATF4 可能是脓毒症治疗的潜在治疗靶点。
