Deaprtment of Surgery, University of Virginia, Charliottesville, VA, USA; Biomedical Engineering University of Virginia, Charlottesville, Virginia; Department of General Thoracic Surgery, Graduate School of Medicine, Chiba University, Chiba, Japan.
Department of Surgery, University of Maryland, Baltimore, Maryland.
J Heart Lung Transplant. 2022 Aug;41(8):1044-1054. doi: 10.1016/j.healun.2022.05.009. Epub 2022 May 20.
Long-term survival of lung transplants lags behind other solid organs due to early onset of a fibrotic form of chronic rejection known as chronic lung allograft dysfunction (CLAD). Preventing CLAD is difficult as multiple immunologic and physiologic insults contribute to its development. Targeting fibroblast activation, which is the final common pathway leading to CLAD, offers the opportunity to ameliorate fibrosis irrespective of the initiating insult. Thy-1 is a surface glycoprotein that controls fibroblast differentiation and activation.
To study the role of Thy-1 in CLAD, we utilized the minor antigen mismatched C57BL/6 (B6) or B6→C57BL/10 (B10) model of murine orthotopic lung transplantation with postoperative bacterial infection modeled by intratracheal lipopolysaccharide (LPS) administration. The effects of LPS on Thy-1 expression, proliferation, and gene expression were assessed in fibroblasts in vitro and the therapeutic potential of Thy-1 replacement was assessed in vivo.
More severe CLAD was evident in B6 →B10 grafts compared to B6 →B10 grafts. LPS further accentuated fibrosis in B6 →B10 grafts with some, but limited, effects on B6 →B10 grafts. LPS contributed to Thy-1 loss from Thy-1(+) fibroblasts in vitro due to a decrease in mRNA expression. In addition, LPS promoted proliferation and upregulation of multiple inflammatory pathways in Thy-1(-) fibroblasts by gene expression analysis. Most importantly, replacement of Thy-1 through exogenous administration ameliorated the fibrotic phenotype post-LPS mediated modeling of infection.
Our findings suggest that the loss of Thy-1 on fibroblasts is a previously unrecognized cause of CLAD and its replacement may offer therapeutic applications for amelioration of this disease post-transplantation in the setting of infectious stress responses.
由于一种称为慢性肺移植物功能障碍（CLAD）的纤维化形式的慢性排斥反应的早期发生，肺移植的长期存活率落后于其他实体器官。由于多种免疫和生理损伤导致其发展，因此预防 CLAD 较为困难。靶向成纤维细胞激活是导致 CLAD 的最终共同途径，为改善纤维化提供了机会，而与起始损伤无关。Thy-1 是一种表面糖蛋白，可控制成纤维细胞分化和激活。
为了研究 Thy-1 在 CLAD 中的作用，我们利用了次要抗原不匹配的 C57BL/6（B6）或 B6→C57BL/10（B10）的小鼠原位肺移植模型，并通过气管内脂多糖（LPS）给药模拟术后细菌感染。评估了 LPS 在体外成纤维细胞中对 Thy-1 表达、增殖和基因表达的影响，并评估了 Thy-1 替代的治疗潜力。
与 B6→B10 移植物相比，B6→B10 移植物中更严重的 CLAD 明显。LPS 进一步加重了 B6→B10 移植物的纤维化，对 B6→B10 移植物的影响有限。LPS 通过体外降低 mRNA 表达导致 Thy-1（+）成纤维细胞中 Thy-1 的丧失。此外，LPS 通过基因表达分析促进了 Thy-1（-）成纤维细胞的增殖和多种炎症途径的上调。最重要的是，通过外源性给予 Thy-1 可以改善 LPS 介导的感染建模后的纤维化表型。
我们的研究结果表明，成纤维细胞中 Thy-1 的丧失是 CLAD 的一个以前未被认识的原因，其替代可能为移植后感染应激反应中改善这种疾病提供治疗应用。
