Ciesielski C J, Mei J, Piccinini L A
Department of Cell Biology, Neurobiology and Anatomy, Loyola University Chicago, Stritch School of Medicine, Maywood, Illinois, USA.
Transpl Immunol. 1998 Jun;6(2):122-33. doi: 10.1016/s0966-3274(98)80027-0.
Recent advances in the study of the molecular basis of inflammation suggest that cell-cell interactions mediated by specific adhesion molecules could be new targets for immunosuppression. Methotrexate (MTX)-treated cells in vitro have demonstrated decreased neutrophil-endothelial cell adhesion associated with increased release of adenosine from endothelial cells, while the direct role of cyclosporine A (CSA) in the regulation of cell adhesion molecule (CAM) expression is less well-defined. Since the adhesion of leucocytes to endothelial cells via CAMs is necessary for leucocyte extravasation and infiltration into graft tissue during allograft rejection, these studies have addressed the hypothesis that MTX treatment of cardiac transplant recipients may affect cellular adherence by downregulating cell adhesion molecule expression. Using a vascularized method of rat cardiac transplantation, our studies have previously demonstrated that low doses of the immunosuppressive agents CSA and MTX, when used in combination, significantly increase allograft survival. According to reverse transcriptase-polymerase chain reaction (RT-PCR) methodology to measure changes in steady-state CD18 mRNA levels, and immunohistochemistry to assess transplant CD18 protein levels in situ, both CD18 transcript and protein levels were significantly increased in untreated allografts when compared to isograft tissues on days 3 through to 7 post-transplant. Whereas, both low-dose CSA alone and low-dose MTX alone treatment resulted in similar levels of graft leucocyte infiltration, MTX-treated recipients demonstrated lower levels of CD18 expression when compared to low-dose CSA alone treatment. The results of immunohistochemical staining for T cells, where significantly fewer T cells were observed in rat cardiac allografts after low-dose MTX treatment alone compared to low-dose CSA treatment, were noteworthy. Results of these studies indicate that CD18 expression and infiltrating T cell numbers in Brown Norway (BN) to Lewis (Lew) rat cardiac allografts are significantly diminished with low-dose MTX treatment. The immunosuppressive effects of MTX, therefore, may be related to its ability to interfere with an early step during the cell-mediated immune response, namely the firm binding or 'adhesion' of leucocytes to the endothelium during transendothelial migration.
炎症分子基础研究的最新进展表明，由特定黏附分子介导的细胞间相互作用可能成为免疫抑制的新靶点。体外经甲氨蝶呤（MTX）处理的细胞已显示出中性粒细胞与内皮细胞的黏附减少，这与内皮细胞中腺苷释放增加有关，而环孢素A（CSA）在调节细胞黏附分子（CAM）表达方面的直接作用尚不太明确。由于在同种异体移植排斥反应期间，白细胞通过CAMs与内皮细胞的黏附是白细胞渗出并浸润到移植组织所必需的，这些研究探讨了MTX治疗心脏移植受者可能通过下调细胞黏附分子表达来影响细胞黏附的假说。使用大鼠心脏移植的血管化方法，我们的研究先前已证明，低剂量的免疫抑制剂CSA和MTX联合使用时，可显著提高同种异体移植的存活率。根据逆转录聚合酶链反应（RT-PCR）方法测量稳态CD18 mRNA水平的变化，以及免疫组织化学方法原位评估移植组织中CD18蛋白水平，与移植后第3天至第7天的同基因移植组织相比，未经处理的同种异体移植组织中的CD18转录本和蛋白水平均显著增加。然而，单独使用低剂量CSA和单独使用低剂量MTX治疗导致的移植物白细胞浸润水平相似，但与单独使用低剂量CSA治疗相比，MTX治疗的受者CD18表达水平较低。单独低剂量MTX治疗后大鼠心脏同种异体移植中观察到的T细胞明显少于低剂量CSA治疗，T细胞免疫组织化学染色结果值得注意。这些研究结果表明，低剂量MTX治疗可显著减少棕色挪威（BN）大鼠到刘易斯（Lew）大鼠心脏同种异体移植中的CD18表达和浸润T细胞数量。因此，MTX的免疫抑制作用可能与其干扰细胞介导的免疫反应早期步骤的能力有关，即在跨内皮迁移过程中白细胞与内皮的牢固结合或“黏附”。
