Targeting Fibroblast Discoidin Domain Receptor 2 for Immunotherapy to Pulmonary Fibrosis

进行性肺纤维化是一种可导致快速死亡的破坏性疾病，目前的治疗方法是 只是适度有效。用Nindestrin抑制酪氨酸激酶已被证明是一种成功的治疗方法 治疗多种肺纤维化疾病的策略。然而，由于Necrosis的非特异性， 不清楚哪些酪氨酸激酶对驱动纤维化最关键。未来的机制研究应侧重于 鉴定参与纤维化的特定酪氨酸激酶和细胞类型， 重要的促纤维化途径我们已经确定盘状结构域受体2（DDR2）作为一个有吸引力的 治疗靶点DDR2是由纤维状胶原如I型胶原激活的酪氨酸激酶受体 我们最近发现I型胶原蛋白信号能促进成纤维细胞的进一步活化， 前馈/正反馈循环最终导致进行性纤维化。此外，与DDR 1不同， 由于DDR2在许多细胞类型中高度表达，因此DDR2表达严重偏斜， 成纤维细胞比其他类型的细胞。这是至关重要的，因为我们最近报道，激活无处不在的 细胞内信号传导途径可以对纤维化具有相反的作用，这取决于具有促纤维化因子的细胞类型。 在成纤维细胞内的纤维化活化，但在上皮细胞内的抗纤维化作用。因此，DDR2可以实现更多 特异性靶向作为主要纤维化效应细胞的成纤维细胞。最近，一种新的DDR2专用 抑制剂已显示通过抑制与肺癌相关癌症而改善肺癌模型的结果 成纤维细胞和表达DDR2的癌细胞经历了间充质转化。初步 数据我们发现这种抑制剂在抑制纤维化方面也有效。我们的初步数据也支持一种新的 DDR2信号调节PIK 3C 2 α的机制，PIK 3C 2 α是PI 3激酶的一个鲜为人知的成员 该家族最近显示调节TGFβ信号传导所必需的TGFβ受体内化。 PIK 3C α也被证明可以调节PDK 1/Akt信号传导，这与我们的报告一致，即DDR2调节PDK 1/Akt信号传导。 成纤维细胞存活通过PDK 1/Akt。最后，最近的一份报告发现，靶向成纤维细胞特异性标记物， 使用嵌合抗原受体（CAR）-T细胞方法有效地减弱了心脏纤维化。 总的来说，这支持了我们的中心假设，即DDR2通过成纤维细胞特异性作用促进纤维化 通过PIK 3C 2 α/PDK/Akt信号通路抑制细胞凋亡，DDR2 代表抗纤维化治疗的有吸引力的靶点。除了测试DDR2与 考虑到DDR2的偏高成纤维细胞表达，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， 不经历克隆扩增，因此可以用作具有最小 毒性这些研究将促进我们对一个关键的促纤维化信号通路的理解， 推进和完善适应CAR免疫疗法治疗纤维化的潜力。

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.