Mesenchymal Cell Dysfunction in Fibroproliferative Lung Disease

摘要 进行性纤维化是导致主要发病率和死亡率的原因之一，特发性肺纤维化就是最好的例证。 纤维化(IPF)。控制持续性肺纤维化的分子机制仍然知之甚少。在.期间 在PO1的资助期，我们发现了一种侵袭性成纤维细胞表型，它似乎是一种重要的 顽固性肺纤维化的特点。我们已经确定了导致重症肺的侵袭性成纤维细胞 小鼠和人的纤维化，侵袭性表型需要HAS2，CD44和β-抑制素。成纤维细胞 谱系追踪研究证实T盒基因4(Tbx4)谱系间充质祖细胞是 损伤的成年小鼠肺中肌成纤维细胞的主要来源。为了进一步分析遗传调控的机制 成纤维细胞的侵袭，我们对一组侵袭性和非侵袭性的成纤维细胞样本进行了RNA-seq分析。 IPF患者。出乎意料的是，我们发现包括检查点PD1配体在内的几种免疫分子， PD-L1(CD274)和PD-L2(CD273)在侵袭性人成纤维细胞中显著上调。 程序性死亡-1(PD-1，CD279)途径是免疫系统的一种动态平衡机制， 防止自身免疫和失控的炎症，也被癌细胞用来逃避免疫 监视系统。这是一个耐人寻味的新发现，特别是考虑到FDA批准了多- 酪氨酸激酶抑制剂inetedanib用于IPF，这是一种最初用于癌症的药物。一种范式已经演变 IPF的病理生物学更类似于癌症，而不是慢性炎症。然而，PD的作用-- 1/PD-L1在肺纤维化中的作用尚不清楚。我们的初步研究表明，PD-L1调节成纤维细胞的黏附， 迁徙和入侵。我们发现粘着斑组分包括粘着斑激酶(FAK)。 和Rho/Rock大幅上调。最近，与加州大学洛杉矶分校的约翰·贝尔佩里奥博士合作， PI在项目3中，我们还鉴定了慢性肺移植患者中的侵袭性成纤维细胞 功能障碍(CLAD)，这是肺移植后发病率和死亡率的主要原因。我们 建议在这些细胞中进行类似的方法，以期确定治疗COLAD的新靶点。 我们已经开始研究PD-L1的调节，发现PD-L1在肺中被P53下调 成纤维细胞。与免疫检查点基因相比，p53在侵袭性成纤维细胞中显著下调， 与癌细胞中的情况类似。P53在肝纤维化中的表达和作用已引起人们的广泛关注。 但P53在成纤维细胞中的作用还没有得到彻底的研究。看起来，P53的作用可能不是 不仅在防止上皮细胞凋亡，而且在成纤维细胞侵袭方面，从而提供了两种截然不同的 肺纤维化发病机制的研究进展。综上所述，我们假设P53的丢失- 调节肺成纤维细胞的免疫检查点基因，导致PD-1配体介导的逃避激活 免疫检测、局灶性黏附和细胞侵袭性。

Abstract Progressive fibrosis is a cause of major morbidity and mortality as best exemplified by idiopathic pulmonary fibrosis (IPF). The molecular mechanisms that control unremitting lung fibrosis remain poorly understood. During the funding period of this PO1, we identified an invasive fibroblast phenotype that appears to be an important feature of unremitting pulmonary fibrosis. We have identified invasive fibroblasts that contribute to severe lung fibrosis in mouse and human, and the invasive phenotype requires HAS2, CD44, and beta-arrestins. Fibroblast lineage-tracing studies identified that T box gene 4 (Tbx4)-lineage mesenchymal progenitors are the predominant source of myofibroblasts in injured adult murine lung. To further analyze the genetic regulation of fibroblast invasion, we performed RNA-seq analysis of a set of invasive and noninvasive fibroblast samples from IPF patients. Unexpectedly, we found that several immune molecules including both checkpoint PD1 ligands, PD-L1 (CD274) and PD-L2 (CD273), are significantly upregulated preferentially on invasive human fibroblasts. The Programmed Death-1 (PD-1, CD279) pathway is a homeostatic mechanism of the immune system that prevents autoimmunity and uncontrolled inflammation, and it is also used by cancer cells to escape from immune surveillance. This is an intriguing and novel discovery, particularly in light of the FDA approval of the multi- tyrosine kinase inhibitor nintedanib for IPF, a drug that was initially developed for cancer. A paradigm has evolved that the pathobiology of IPF is more similar to cancer than to chronic inflammation. However, the role of PD- 1/PD-L1 in lung fibrosis is unknown. Our preliminary studies revealed that PD-L1 regulates fibroblast adhesion, migration and invasiveness. We found that the focal adhesion components including focal adhesion kinase (FAK) and Rho/ROCK are significantly up-regulated. More recently, in collaboration with Dr. John Belperio at UCLA, PI on Project 3, we have also identified invasive fibroblasts in patients suffering from chronic lung allograft dysfunction (CLAD), which is the major cause of morbidity and mortality following lung transplantation. We propose to perform a similar approach in these cells with the hope of identifying new targets for therapy of CLAD. We have begun to examine the regulation of PD-L1 and found that PD-L1 was down-regulated by p53 in lung fibroblasts. In contrast to the immune checkpoint genes, p53 is markedly down-regulated in invasive fibroblasts, similar to that in cancer cells. Much attention has been paid to epithelial p53 expression and function in fibrosis, but the role of p53 in fibroblasts has not been thoroughly investigated. It appears that p53 may have a role not only in preventing epithelial apoptosis, but also in fibroblast invasiveness, thereby providing two distinct mechanisms in the pathogenesis of pulmonary fibrosis. Taken together, we hypothesize that loss of p53 up- regulates immune checkpoint genes in lung fibroblasts, leading to the activation of PD-1 ligand-mediated evasion of immune detection, focal adhesion and cell invasiveness.