Carter Immunology Center (T.P., M.M., P.S., J.C.G., A.H., C.A.M.), University of Virginia, Charlottesville. Institute for Cardiovascular Prevention, Ludwig-Maximilians-Universität, Munich, Germany.
Cardiovascular Research Center (T.P., M.M., A.U., P.S., J.C.G., A.H., C.A.M.), University of Virginia, Charlottesville. Institute for Cardiovascular Prevention, Ludwig-Maximilians-Universität, Munich, Germany.
Circ Res. 2022 Apr;130(7):981-993. doi: 10.1161/CIRCRESAHA.121.320436. Epub 2022 Feb 25.
B1a and B1b lymphocytes produce IgM that inactivates oxidation-specific epitopes (IgM) on LDL (low-density lipoprotein) and protects against atherosclerosis. Loss of ID3 (inhibitor of differentiation 3) in B cells selectively promotes B1b but not B1a cell numbers, leading to higher IgM production and reduction in atherosclerotic plaque formation. Yet, the mechanism underlying this regulation remains unexplored.
Bulk RNA sequencing was utilized to identify differentially expressed genes in B1a and B1b cells from KO and WT mice. CRISPR/Cas9 and lentiviral genome editing coupled with adoptive transfer were used to identify key -dependent signaling pathways regulating B1b cell proliferation and the impact on atherosclerosis. Biospecimens from humans with advanced coronary artery disease imaging were analyzed to translate murine findings to human subjects with coronary artery disease.
Through RNA sequencing, P62 was found to be enriched in KO B1b cells. Further in vitro characterization reveals a novel role for P62 in mediating BAFF (B-cell activating factor)-induced B1b cell proliferation through interacting with TRAF6 (tumor necrosis factor receptor 6) and activating NF-κB (nuclear factor kappa B), leading to subsequent C-MYC (C-myelocytomatosis) upregulation. Promoter-reporter assays reveal that Id3 inhibits the E2A protein from activating the P62 promoter. Mice adoptively transferred with B1 cells overexpressing P62 exhibited an increase in B1b cell number and IgM levels and were protected against atherosclerosis. Consistent with murine mechanistic findings, P62 expression in human B1 cells was significantly higher in subjects harboring a function-impairing single nucleotide polymorphism (SNP) at rs11574 position in the gene and directly correlated with plasma IgM levels.
This study unveils a novel role for P62 in driving BAFF-induced B1b cell proliferation and IgM production to attenuate diet-induced atherosclerosis. Results identify a direct role for Id3 in antagonizing E2A from activating the promoter. Moreover, analysis of putative human B1 cells also implicates these pathways in coronary artery disease subjects, suggesting P62 as a new immunomodulatory target for treating atherosclerosis.
B1a 和 B1b 淋巴细胞产生 IgM，使 LDL（低密度脂蛋白）上的氧化特异性表位失活（IgM），并防止动脉粥样硬化。B 细胞中 ID3（分化抑制剂 3）的缺失选择性地促进 B1b 而非 B1a 细胞数量的增加，导致 IgM 产生增加和动脉粥样硬化斑块形成减少。然而，这种调节的机制仍未被探索。
利用批量 RNA 测序鉴定 KO 和 WT 小鼠 B1a 和 B1b 细胞中差异表达的基因。CRISPR/Cas9 和慢病毒基因组编辑与过继转移相结合，用于鉴定调节 B1b 细胞增殖的关键依赖性信号通路及其对动脉粥样硬化的影响。分析患有先进冠状动脉疾病成像的人类生物样本，将鼠类研究结果转化为患有冠状动脉疾病的人类患者。
通过 RNA 测序，发现 P62 在 KO B1b 细胞中富集。进一步的体外特征揭示了 P62 在介导 BAFF（B 细胞激活因子）诱导的 B1b 细胞增殖中的新作用，通过与 TRAF6（肿瘤坏死因子受体 6）相互作用并激活 NF-κB（核因子 kappa B），导致随后的 C-MYC（C-myelocytomatosis）上调。启动子报告基因分析显示，Id3 抑制 E2A 蛋白激活 P62 启动子。过继转移表达 P62 的 B1 细胞的小鼠，B1b 细胞数量和 IgM 水平增加，并能抵抗动脉粥样硬化。与鼠类机制研究结果一致，在携带位于 基因 rs11574 位置的功能丧失性单核苷酸多态性（SNP）的受试者中，人 B1 细胞中的 P62 表达明显更高，并且与血浆 IgM 水平直接相关。
本研究揭示了 P62 在驱动 BAFF 诱导的 B1b 细胞增殖和 IgM 产生以减轻饮食诱导的动脉粥样硬化中的新作用。结果表明，Id3 直接作用于拮抗 E2A 激活 启动子。此外，对推定的人 B1 细胞的分析也表明这些途径在冠状动脉疾病患者中起作用，表明 P62 是治疗动脉粥样硬化的新免疫调节靶点。
