Li Yao, Li Tingting, Xiao Fei, Wang Lijun, Liao Xuelian, Zhang Wei, Kang Yan
Department of Critical Care Medicine, West China Hospital, Sichuan University, Chengdu, Sichuan 610041, China.
Institute of Critical Care Medicine, West China Hospital, Sichuan University, Chengdu, Sichuan 610041, China.
Chin Med J (Engl). 2025 Jul 5;138(13):1607-1620. doi: 10.1097/CM9.0000000000003606. Epub 2025 Apr 27.
Immunosuppression is closely related to the pathogenesis of sepsis, but the underlying mechanisms have not yet been fully elucidated. In this study, we aimed to examine the role of the Sterile Alpha Motif, Src Homology 3 domain and nuclear localization signal 1 (SAMSN1) in sepsis and elucidate its potential molecular mechanism in sepsis induced immunosuppression.
RNA sequencing databases were used to validate SAMSN1 expression in sepsis. The impact of SAMSN1 on sepsis was verified using gene knockout mice. Flow cytometry was employed to delineate how SAMSN1 affects immunity in sepsis, focusing on immune cell types and T cell functions. Clustered regularly interspaced short palindromic repeats (CRISPR)/CRISPR-associated protein 9 (Cas9)-mediated gene editing in RAW264.7 macrophages enabled interrogation of SAMSN1 's regulatory effects on essential macrophage functions, including cell proliferation and phagocytic capacity. The mechanism of SAMSN1 in the interaction between macrophages and T cells was investigated using the RAW264.7 cell line and primary cell lines.
SAMSN1 expression was significantly increased in patients with sepsis and was positively correlated with sepsis mortality. Genetic deletion of Samsn1 in murine sepsis model improved T cell survival, elevated T cell cytolytic activity, and activated T cell signaling transduction. Concurrently, Samsn1 knockout augmented macrophage proliferation capacity and phagocytic efficiency. In macrophage, SAMSN1 binds to Kelch-like epichlorohydrin-associated protein 1 (KEAP1), causing nuclear factor erythroid 2-related factor 2 (NRF2) to dissociate from the KEAP1-NRF2 complex and translocate into the nucleus. This promotes the transcription of the coinhibitory molecules CD48/CD86/carcinoembryonic antigen related cell adhesion molecule 1 (CEACAM1), which bind to their corresponding receptors natural killer cell receptor 2B4/CD152/T cell immunoglobulin and mucin domain-containing protein 3 (TIM3) on the surface of T cells, inducing T-cell exhaustion.
SAMSN1 deletion augmented adaptive T cell immunity and macrophage phagocytic-proliferative dual function. Furthermore, it mediates the KEAP1-NRF2 axis, which affects the expression of coinhibitory molecules on macrophages, leading to T-cell exhaustion. This novel immunosuppression mechanism potentially provides a candidate molecular target for sepsis immunotherapy.
免疫抑制与脓毒症的发病机制密切相关，但其潜在机制尚未完全阐明。在本研究中，我们旨在探讨无菌α基序、Src同源3结构域和核定位信号1（SAMSN1）在脓毒症中的作用，并阐明其在脓毒症诱导的免疫抑制中的潜在分子机制。
利用RNA测序数据库验证脓毒症中SAMSN1的表达。使用基因敲除小鼠验证SAMSN1对脓毒症的影响。采用流式细胞术描述SAMSN1如何影响脓毒症中的免疫，重点关注免疫细胞类型和T细胞功能。在RAW264.7巨噬细胞中使用成簇规律间隔短回文重复序列（CRISPR）/CRISPR相关蛋白9（Cas9）介导的基因编辑来探究SAMSN1对巨噬细胞基本功能的调节作用，包括细胞增殖和吞噬能力。使用RAW264.7细胞系和原代细胞系研究SAMSN1在巨噬细胞与T细胞相互作用中的机制。
脓毒症患者中SAMSN1表达显著增加，且与脓毒症死亡率呈正相关。在小鼠脓毒症模型中基因敲除Samsn1可改善T细胞存活，提高T细胞溶细胞活性，并激活T细胞信号转导。同时，敲除Samsn1可增强巨噬细胞增殖能力和吞噬效率。在巨噬细胞中，SAMSN1与kelch样环氧氯丙烷相关蛋白1（KEAP1）结合，导致核因子红细胞2相关因子2（NRF2）从KEAP1-NRF2复合物中解离并转运至细胞核。这促进了共抑制分子CD48/CD86/癌胚抗原相关细胞黏附分子1（CEACAM1）的转录，它们与T细胞表面相应受体自然杀伤细胞受体2B4/CD152/T细胞免疫球蛋白和含黏蛋白结构域蛋白3（TIM3）结合，诱导T细胞耗竭。
敲除SAMSN1可增强适应性T细胞免疫和巨噬细胞吞噬-增殖双重功能。此外，它介导KEAP1-NRF2轴，影响巨噬细胞上共抑制分子的表达，导致T细胞耗竭。这种新的免疫抑制机制可能为脓毒症免疫治疗提供一个候选分子靶点。
