Chinese Academy of Sciences (CAS) Key Laboratory of Tissue Microenvironment and Tumor, Shanghai Institute of Nutrition and Health, University of Chinese Academy of Sciences, Chinese Academy of Sciences, Shanghai, China.
Department of Clinical Immunology, Children's Hospital of Fudan University, National Children's Medical Center, Shanghai, China.
Front Immunol. 2024 Apr 8;15:1364957. doi: 10.3389/fimmu.2024.1364957. eCollection 2024.
CARD11 is a lymphoid lineage-specific scaffold protein regulating the NF-κB activation downstream of the antigen receptor signal pathway. Defective CARD11 function results in abnormal development and differentiation of lymphocytes, especially thymic regulatory T cells (Treg).
In this study, we used patients' samples together with transgenic mouse models carrying pathogenic mutations from patients to explore their effects on Treg development. Immunoblotting and a GFP receptor assay were used to evaluate the activation effect of CARD11 mutants on NF-κB signaling. Then the suppressive function of Tregs carrying distinct CARD11 mutations was measured by suppression assay. Finally, we applied the retroviral transduced bone marrow chimeras to rescue the Treg development in an NF-κB independent manner.
We found CARD11 mutations causing hyper-activated NF-κB signals also gave rise to compromised Treg development in the thymus, similar to the phenotype in Card11 deficient mice. This observation challenges the previous view that CARD11 regulates Treg lineage dependent on the NF-kB activation. Mechanistic investigations reveal that the noncanonical function CARD11, which negatively regulates the AKT/ FOXO1 signal pathway, is responsible for regulating Treg generation. Moreover, primary immunodeficiency patients carrying CARD11 mutation, which autonomously activates NF-κB, also represented the reduced Treg population in their peripheral blood. Our results propose a new regulatory function of CARD11 and illuminate an NF-κB independent pathway for thymic Treg lineage commitment.
CARD11 是一种淋巴细胞谱系特异性支架蛋白，调节抗原受体信号通路下游的 NF-κB 激活。CARD11 功能缺陷导致淋巴细胞，尤其是胸腺调节性 T 细胞（Treg）的发育和分化异常。
在这项研究中，我们使用患者样本和携带患者致病突变的转基因小鼠模型来探索它们对 Treg 发育的影响。免疫印迹和 GFP 受体测定用于评估 CARD11 突变体对 NF-κB 信号的激活作用。然后通过抑制试验测量携带不同 CARD11 突变的 Tregs 的抑制功能。最后，我们应用逆转录病毒转导的骨髓嵌合体以非 NF-κB 依赖的方式拯救 Treg 发育。
我们发现导致 NF-κB 信号过度激活的 CARD11 突变也导致胸腺中 Treg 发育受损，类似于 Card11 缺陷小鼠的表型。这一观察结果挑战了以前的观点，即 CARD11 通过 NF-kB 激活调节 Treg 谱系。机制研究表明，负调节 AKT/FOXO1 信号通路的 CARD11 的非经典功能负责调节 Treg 的产生。此外，携带自主激活 NF-κB 的 CARD11 突变的原发性免疫缺陷患者在其外周血中也表现出 Treg 群体减少。我们的结果提出了 CARD11 的新调节功能，并阐明了胸腺 Treg 谱系决定的非 NF-κB 途径。
