Department of Pediatric Surgery, Osaka University Graduate School of Medicine, Osaka, Japan.
Department of Pediatric Surgery, Osaka University Graduate School of Medicine, Osaka, Japan.
Immunobiology. 2019 Sep;224(5):605-613. doi: 10.1016/j.imbio.2019.07.008. Epub 2019 Aug 3.
The delayed rejection caused by strong cell-mediated innate and adaptive xenogeneic immune responses continues to be a major obstacle. Therefore, suppressing macrophage function could be effective in avoiding this type of rejection. In this study, the suppression of T-cell immunoglobulin and ITIM domain (TIGIT) function against macrophage-mediated xenogeneic rejection was investigated.
Naïve porcine aortic endothelial cell (PAEC) and PAEC transfectant with TIGIT (PAEC/TIGIT) were co-cultured with M1 macrophages, and the degree of cytotoxicity was determined by a counting beads assay. The anti/pro-inflammatory gene expression was determined by RT-PCR and the phosphorylated SHP-1 in the macrophages after co-culturing with PAEC or PAEC/TIGIT was evaluated by western blotting.
CD155 was expressed at essentially equal levels on both M1 and M2 macrophages, whereas TIGIT was highly expressed on M2 macrophages but not in M1 macrophages. TIGIT on PAEC significantly reduced the cytotoxicity of M1 macrophages but no significant suppression of phagocytosis was detected. TIGIT also caused a decrease in the expression of pro-inflammatory cytokines, namely TNFα, IL-1β and IL-12 in M1 macrophages. Furthermore, PAEC/TIGIT caused a significant increase in phosphorylated SHP-1 in M1 macrophages compared to PAEC.
The findings of this study indicate that TIGIT suppresses xenogeneic M1 macrophage-induced cytotoxicity, probably at least in part, via the phosphorylation of SHP-1. In addition, the reduced expression of some pro-inflammatory cytokines, namely TNFα, IL-1β and IL-12, was observed in M1 macrophages that had been cultured with PAEC/TIGIT.
由强烈的细胞介导的先天和适应性异种免疫反应引起的延迟排斥反应仍然是一个主要障碍。因此，抑制巨噬细胞功能可能是避免这种排斥反应的有效方法。在这项研究中，研究了抑制 T 细胞免疫球蛋白和 ITIM 结构域（TIGIT）功能对巨噬细胞介导的异种排斥反应的作用。
将原代猪主动脉内皮细胞（PAEC）和转染 TIGIT 的 PAEC（PAEC/TIGIT）与 M1 巨噬细胞共培养，并通过计数珠试验测定细胞毒性程度。通过 RT-PCR 测定抗/促炎基因的表达，并用 Western blot 检测共培养后巨噬细胞中磷酸化 SHP-1 的表达。
CD155 在 M1 和 M2 巨噬细胞上的表达水平基本相同，而 TIGIT 在 M2 巨噬细胞上高度表达，但在 M1 巨噬细胞上不表达。PAEC 上的 TIGIT 显著降低了 M1 巨噬细胞的细胞毒性，但未检测到吞噬作用的显著抑制。TIGIT 还导致 M1 巨噬细胞中促炎细胞因子 TNFα、IL-1β 和 IL-12 的表达减少。此外，与 PAEC 相比，PAEC/TIGIT 导致 M1 巨噬细胞中磷酸化 SHP-1 显著增加。
本研究结果表明，TIGIT 通过 SHP-1 的磷酸化抑制异种 M1 巨噬细胞诱导的细胞毒性，至少部分是通过 SHP-1 的磷酸化。此外，在与 PAEC/TIGIT 共培养的 M1 巨噬细胞中观察到某些促炎细胞因子 TNFα、IL-1β 和 IL-12 的表达减少。
