Center for Immunology (L.A.M., J.L.A., B.J.E., H.M.C., M.I.G.-T., B.A.B.).
Department of Pediatrics (L.A.M., J.L.A., M.I.G.-T., B.A.B.).
Circulation. 2018 Jun 5;137(23):2478-2493. doi: 10.1161/CIRCULATIONAHA.117.033144. Epub 2018 Jan 31.
Valvular heart disease is common and affects the mitral valve (MV) most frequently. Despite the prevalence of MV disease (MVD), the cellular and molecular pathways that initiate and perpetuate it are not well understood.
K/B.g7 T-cell receptor transgenic mice spontaneously develop systemic autoantibody-associated autoimmunity, leading to fully penetrant fibroinflammatory MVD and arthritis. We used multiparameter flow cytometry, intracellular cytokine staining, and immunofluorescent staining to characterize the cells in inflamed K/B.g7 MVs. We used genetic approaches to study the contribution of mononuclear phagocytes (MNPs) to MVD in this model. Specifically, we generated K/B.g7 mice in which either CX3CR1 or CD301b/macrophage galactose -acetylgalactosamine-specific lectin 2 (MGL2)-expressing MNPs were ablated. Using K/B.g7 mice expressing -Cre, we conditionally deleted critical inflammatory molecules from MNPs, including the Fc-receptor signal-transducing tyrosine kinase Syk and the cell adhesion molecule very late antigen-4. We performed complementary studies using monoclonal antibodies to block key inflammatory molecules. We generated bone marrow chimeric mice to define the origin of the inflammatory cells present in the MV and to determine which valve cells respond to the proinflammatory cytokine tumor necrosis factor (TNF). Finally, we examined specimens from patients with rheumatic heart disease to correlate our findings to human pathology.
MNPs comprised the vast majority of MV-infiltrating cells; these MNPs expressed CX3CR1 and CD301b/MGL2. Analogous cells were present in human rheumatic heart disease valves. K/B.g7 mice lacking CX3CR1 or in which CD301b/MGL2-expressing MNPs were ablated were protected from MVD. The valve-infiltrating CD301b/MGL2 MNPs expressed tissue-reparative molecules including arginase-1 and resistin-like molecule α. These MNPs also expressed the proinflammatory cytokines TNF and interleukin-6, and antibody blockade of these cytokines prevented MVD. Deleting Syk from CX3CR1-expressing MNPs reduced their TNF and interleukin-6 production and also prevented MVD. TNF acted through TNF receptor-1 expressed on valve-resident cells to increase the expression of vascular cell adhesion molecule-1. Conditionally deleting the vascular cell adhesion molecule-1 ligand very late antigen-4 from CX3CR1-expressing MNPs prevented MVD.
CD301b/MGL2 MNPs are key drivers of autoimmune MVD in K/B.g7 mice and are also present in human rheumatic heart disease. We define key inflammatory molecules that drive MVD in this model, including Syk, TNF, interleukin-6, very late antigen-4, and vascular cell adhesion molecule-1.
心脏瓣膜病很常见，最常影响二尖瓣（MV）。尽管 MV 疾病（MVD）很常见，但启动和持续存在它的细胞和分子途径仍不清楚。
K/B.g7 T 细胞受体转基因小鼠自发地发展出全身性自身抗体相关的自身免疫，导致完全穿透性的纤维炎症性 MVD 和关节炎。我们使用多参数流式细胞术、细胞内细胞因子染色和免疫荧光染色来描述炎症 K/B.g7 MV 中的细胞。我们使用遗传方法来研究单核吞噬细胞（MNPs）在该模型中对 MVD 的贡献。具体来说，我们生成了 K/B.g7 小鼠，其中要么 CX3CR1 要么 CD301b/巨噬细胞半乳糖乙酰半乳糖胺特异性凝集素 2（MGL2）表达的 MNPs 被消除。使用表达 -Cre 的 K/B.g7 小鼠，我们从 MNPs 中条件性缺失关键炎症分子，包括 Fc 受体信号转导酪氨酸激酶 Syk 和细胞粘附分子非常晚期抗原-4。我们使用单克隆抗体进行互补研究以阻断关键炎症分子。我们生成了骨髓嵌合小鼠，以确定 MV 中存在的炎症细胞的起源，并确定哪种瓣膜细胞对促炎细胞因子肿瘤坏死因子（TNF）有反应。最后，我们检查了风湿性心脏病患者的标本，以将我们的发现与人类病理学相关联。
MNPs 构成了 MV 浸润细胞的绝大多数；这些 MNPs 表达了 CX3CR1 和 CD301b/MGL2。在人类风湿性心脏病瓣膜中也存在类似的细胞。缺乏 CX3CR1 的 K/B.g7 小鼠或其中 CD301b/MGL2 表达的 MNPs 被消除的小鼠免受 MVD 的影响。浸润 MV 的 CD301b/MGL2 MNPs 表达了组织修复分子，包括精氨酸酶-1 和抵抗素样分子α。这些 MNPs 还表达了促炎细胞因子 TNF 和白细胞介素-6，并且阻断这些细胞因子的抗体可预防 MVD。从 CX3CR1 表达的 MNPs 中删除 Syk 可减少其 TNF 和白细胞介素-6 的产生，并防止 MVD。TNF 通过在瓣膜驻留细胞上表达 TNF 受体-1 来增加血管细胞粘附分子-1 的表达。从 CX3CR1 表达的 MNPs 中条件性缺失血管细胞粘附分子-1 配体非常晚期抗原-4 可防止 MVD。
CD301b/MGL2 MNPs 是 K/B.g7 小鼠自身免疫性 MVD 的关键驱动因素，也存在于人类风湿性心脏病中。我们定义了驱动该模型中 MVD 的关键炎症分子，包括 Syk、TNF、白细胞介素-6、非常晚期抗原-4 和血管细胞粘附分子-1。
