Targeting Fibroblast Discoidin Domain Receptor 2 for Immunotherapy to Pulmonary Fibrosis

进行性肺纤维化是一种破坏性的疾病，可导致迅速死亡，目前的治疗方法是 效果不是很好。用Nindedanib抑制酪氨酸激酶已被证明是一种成功的治疗方法 针对一些肺纤维化疾病的治疗策略。然而，由于宁达尼的非特异性，它是 目前尚不清楚哪些酪氨酸激酶对推动纤维化最为关键。未来的力学研究应该集中在 识别参与纤维化的特定酪氨酸激酶和细胞类型，可能使更精确的靶向成为可能 关键的促纤维化途径。我们已经发现盘状结构域受体2(DDR2)是一种有吸引力的 治疗靶点。DDR2是一种酪氨酸激酶受体，由纤维状胶原激活，如I型胶原 我们最近发现，I型胶原信号进一步促进成纤维细胞的激活，从而导致 前馈/正反馈循环最终导致进行性纤维化。此外，与DDR1不同的是， 在多种细胞类型中高度表达，DDR2的表达严重倾斜，在 成纤维细胞多于其他细胞类型。这一点很关键，因为我们最近报告了无处不在的激活 细胞内信号通路可能对纤维化具有相反的作用，这取决于细胞类型与前体- 成纤维细胞内的纤维化激活，但上皮细胞内的抗纤维化作用。因此，DDR2可能会实现更多 特异性靶向成纤维细胞，成纤维细胞是主要的促纤维化效应细胞。最近发现了一种新的DDR2特异性 抑制剂已被证明通过抑制与癌症相关的肿瘤而改善肺癌模型的预后 间质转化的成纤维细胞和表达DDR2的癌细胞。在预赛中 我们发现这种抑制剂在抑制纤维化方面也是有效的。我们的初步数据也支持一种 DDR2信号调节PI3C2α的机制，PI3是一个知之甚少的PI3激酶成员 该家族最近被证明调节转化生长因子β受体内化，是转化生长因子β信号转导所必需的。 PIK3CDDR2也被证明调节PDK1/Akt信号，这与我们的报告一致，即α调节 成纤维细胞通过PDK1/Akt存活。最后，最近的一份报告发现，靶向成纤维细胞的特定标记物 使用嵌合抗原受体(CAR)-T细胞方法在减轻心肌纤维化方面有效。 总而言之，这支持了我们的中心假设，即DDR2通过成纤维细胞的特异性效应促进纤维化 关于PIK3C2α/转化生长因子β信号、通过PIK3C2α/PDK/AKT信号和DDR2抵抗细胞凋亡 代表了抗纤维化治疗的一个有吸引力的靶点。除了用一种 小分子抑制剂，鉴于DDR2在成纤维细胞中的偏向高表达，我们将开发CAR-NK细胞 靶向DDR2用于肺纤维化的免疫治疗。与T细胞不同，NK细胞不受MHC限制，对吗？ 不进行克隆扩增，因此可以作为现成的治疗方案，最低限度 毒性。这些研究将促进我们对关键的促纤维化信号通路的理解，以及 推进和完善适应CAR免疫疗法治疗纤维化的可能性。

Progressive pulmonary fibrosis is a devastating condition that can lead to rapid death and current therapy is only modestly effective. Tyrosine kinase inhibition with Nindedanib has proven to be a successful therapeutic strategy for a number of pulmonary fibrosis disorders. However, due to the nonspecificity of Nintedanib it is unclear which tyrosine kinases are most critical for driving fibrosis. Future mechanistic studies should focus on identifying specific tyrosine kinases and cell types involved in fibrosis which may enable more precise targeting of critical pro-fibrotic pathways. We have identified discoidin domain receptor 2 (DDR2) as an attractive therapeutic target. DDR2 is a tyrosine kinase receptor activated by fibrillar collagens such as type I collagen and we have recently shown that type I collagen signaling promotes further fibroblast activation leading to a feed forward/postive feedback loop culminating in progressive fibrosis. Furthermore, unlike DDR1, which is highly expressed by many cell types, DDR2 expression is heavily skewed with much higher expression on fibroblasts than other cell types. This is critical because we have recently reported that activation of ubiquitous intracellular signaling pathways can have opposing effects on fibrosis depending on the cell type with pro- fibrotic activation within fibroblasts but anti-fibrotic effects within epithelial cells. Thus, DDR2 may enable more specific targeting of fibroblasts which are the primary fibrogenic effector cells. Recently a novel DDR2-specific inhibitor has been shown to improve outcome in a model of lung cancer through inhibition of cancer associated fibroblasts and DDR2-expressing cancer cells which have undergone mesenchymal transition. In preliminary data we find that this inhibitor is also effective at inhibiting fibrosis. Our preliminary data also support a novel mechanism by which DDR2 signaling regulates PIK3C2α, a poorly understood member of the PI3 kinase family which has recently been shown to regulate TGFβ receptor internalization necessary for TGFβ signaling. PIK3Cα has also been shown to regulate PDK1/Akt signaling consistent with our report that DDR2 regulates fibroblast survival through PDK1/Akt. Finally, a recent report found that targeting fibroblast specific markers using a chimeric antigen receptor (CAR)-T cell approach was effective at attenuating cardiac fibrosis. Collectively, this support our central hypothesis that DDR2 promotes fibrosis through fibroblast specific effects on PIK3C2α/TGFβ signaling, resistance to apoptosis via PIK3C2α/PDK/Akt signaling and that DDR2 represents an attractive target for anti-fibrotic therapy. In addition to testing the importance of DDR2 with a small molecule inhibitor, given skewed high fibroblast expression of DDR2, we will develop CAR-NK cells targeting DDR2 for immunotherapy of pulmonary fibrosis. Unlike T cells, NK cells are not MHC restricted, do not undergo clonal expansion and may therefore serve as off-the shelf therapeutic solution with minimum toxicity. These studies will advance our understanding of a critical pro-fibrotic signaling pathway as well as advance and refine the potential for adapting CAR immunotherapy for fibrosis.