Department of Pathology and Laboratory Medicine, University of California, Los Angeles, California, USA.
Department of Immunology, Leiden University Medical Center, Leiden, the Netherlands.
Am J Transplant. 2024 Mar;24(3):406-418. doi: 10.1016/j.ajt.2023.10.020. Epub 2023 Oct 29.
HLA donor-specific antibodies (DSA) elicit alloimmune responses against the graft vasculature, leading to endothelial cell (EC) activation and monocyte infiltration during antibody-mediated rejection (AMR). AMR promotes chronic inflammation and remodeling, leading to thickening of the arterial intima termed transplant vasculopathy or cardiac allograft vasculopathy (CAV) in heart transplants. Intragraft-recipient macrophages serve as a diagnostic marker in AMR; however, their polarization and function remain unclear. In this study, we utilized an in vitro Transwell coculture system to explore the mechanisms of monocyte-to-macrophage polarization induced by HLA I DSA-activated ECs. Anti-HLA I (IgG or F(ab')) antibody-activated ECs induced the polarization of M2 macrophages with increased CD206 expression and MMP9 secretion. However, inhibition of TLR4 signaling or PSGL-1-P-selectin interactions significantly decreased both CD206 and MMP9. Monocyte adherence to Fc-P-selectin coated plates induced M2 macrophages with increased CD206 and MMP9. Moreover, Fc-receptor and IgG interactions synergistically enhanced active-MMP9 in conjunction with P-selectin. Transcriptomic analysis of arteries from DSA+CAV+ rejected cardiac allografts and multiplex-immunofluorescent staining illustrated the expression of CD68+CD206+CD163+MMP9+ M2 macrophages within the neointima of CAV-affected lesions. These findings reveal a novel mechanism linking HLA I antibody-activated endothelium to the generation of M2 macrophages which secrete vascular remodeling proteins contributing to AMR and CAV pathogenesis.
HLA 供体特异性抗体（DSA）引起针对移植物血管的同种免疫反应，导致抗体介导的排斥反应（AMR）期间血管内皮细胞（EC）活化和单核细胞浸润。AMR 促进慢性炎症和重塑，导致动脉内膜增厚，在心脏移植中称为移植血管病或心脏同种异体移植物血管病（CAV）。移植内受者巨噬细胞作为 AMR 的诊断标志物；然而，它们的极化和功能仍不清楚。在这项研究中，我们利用体外 Transwell 共培养系统来探讨 HLA I DSA 激活的 EC 诱导单核细胞向巨噬细胞极化的机制。抗 HLA I（IgG 或 F(ab')）抗体激活的 EC 诱导 M2 巨噬细胞极化，表现为 CD206 表达增加和 MMP9 分泌增加。然而，TLR4 信号通路或 PSGL-1-P-选择素相互作用的抑制显著降低了 CD206 和 MMP9。单核细胞黏附到 Fc-P-选择素包被的平板上诱导 M2 巨噬细胞，增加 CD206 和 MMP9。此外，Fc 受体和 IgG 相互作用协同增强了与 P-选择素结合的活性-MMP9。来自 DSA+CAV+排斥的心脏移植物的动脉转录组分析和多重免疫荧光染色显示，在 CAV 病变的新生内膜中存在 CD68+CD206+CD163+MMP9+M2 巨噬细胞。这些发现揭示了一种新的机制，将 HLA I 抗体激活的内皮细胞与 M2 巨噬细胞的生成联系起来，后者分泌血管重塑蛋白，导致 AMR 和 CAV 的发病机制。
