Macrophage driven, profibrotic adrenergic nerve remodeling in SSc-ILD

硬皮病是一种难以治疗且知之甚少的自身免疫性疾病，其特征是皮肤和 内脏纤维化，以雷诺现象为形式的交感神经过度活动，以及疤痕堆积- 促进巨噬细胞等先天免疫细胞。尽管公认的临床关系是 对于这些实体，既没有提出也没有显示出一种机械的联系。因为我们有悠久的历史 由于对Netrin-1等神经导向蛋白(NGPs)在SSc-ILD中的作用感兴趣，我们决定研究 Netrin-1是否能够连接这些进程。Netrin-1是一种分泌型的层粘连蛋白样蛋白，通过 与依赖受体的吸引和排斥相互作用调节损伤、炎症、 改建和修缮。在发育中的中枢神经系统中，NTN-1引导轴突的迁移，而在外周，NTN-1引导轴突的迁移。 1通过与其诱人的相互作用，引导出生后肾上腺素能神经支配和感觉神经再生 结直肠癌中的受体缺失。然而，尽管对神经相关的兴趣与日俱增 外周器官损伤和修复的机制，基本上对NTN-1如何相互作用一无所知 在纤维化的肺中有肾上腺素能神经支配，而神经衍生信号越来越多地被认为是 巨噬细胞功能的调节，即巨噬细胞相互维持和重塑的过程 健康和患病肺中的肾上腺素能神经尚不清楚。鉴于SSC已知的与同情的联系 功能障碍，更好地理解肾上腺素能神经在SSc-ILD中是如何重塑和维持的 允许对纤维化的神经科学有基本的见解。在此应用程序中，我们使用鼠标建模和 SSC-ILD组织显示异常的肾上腺素能神经支配，增强的去甲肾上腺素(NA)，和NA- 纤维化肺中的反应性成纤维细胞。这些因素相互作用，推动纤维化，而纤维化可以通过 化学交感神经切除，药物抑制α1肾上腺素能受体，或特异性缺失NTN- 1例来自巨噬细胞。这些发现支持巨噬细胞源自Netrin-1等信号的假设 促进肺内促纤维化肾上腺素能神经重塑，将从三个目标进行探索。此应用程序 联合了肺部生物学、硬皮病、先天免疫、肾上腺素能神经支配、Netrin-1、 和神经科学进行一个综合项目，使用两个动物模型，细胞特异性基因敲除小鼠，屏蔽 骨髓嵌合体，药理受体激活和抑制，人体细胞和 组织、精确切割的肺切片、单细胞测序方法和微型CT。目标1将决定 肾上腺素能神经源性NA驱动肺纤维化的机制。目标2将决定 Netrin-1巨噬细胞调节肺纤维化的机制(S)。目标3将定义如何 巨噬细胞来源的Netrin-1控制损伤后肾上腺素能神经重建。这些研究有可能 产生范式转变的结果，这将改变我们看待纤维化的方式，并可能开发出新的 SSc-ILD的治疗。

Scleroderma is a difficult to treat and poorly understood autoimmune condition characterized by dermal and visceral fibrosis, sympathetic overactivity in the form of Raynaud’s phenomenon, and the accumulation of scar- promoting innate immune cells such as macrophages. Despite the well accepted clinical relationship between these entities, a mechanistic link has been neither proposed nor shown. Because we have a longstanding interest in the role of neuronal guidance proteins (NGPs) such as Netrin-1 in SSc-ILD, we decided to study whether Netrin-1 could connect these processes. Netrin-1 is a secreted, laminin-like protein that through attractive and repulsive interactions with dependence receptors regulates critical events in injury, inflammation, remodeling, and repair. In the developing CNS, NTN-1 guides the migration of axons, and in the periphery NTN- 1 guides both postnatal adrenergic innervation and sensory nerve regeneration via interactions with its attractive receptor deleted in colorectal carcinoma (DCC). However, despite growing interest in nerve associated mechanisms of injury and repair in peripheral organs, essentially nothing is known about how NTN-1 interacts with adrenergic innervation in the fibrotic lung and, while nerve-derived signals are increasingly recognized as regulators of macrophage function, the process by which macrophages might reciprocally maintain and remodel adrenergic nerves in the healthy and diseased lung is obscure. Given SSc’s known association with sympathetic dysfunction, better understanding of how adrenergic nerves are remodeled and maintained in SSc-ILD could allow fundamental insights into the neuroscience of fibrosis. In this application we use mouse modeling and SSc-ILD tissues to demonstrate aberrant adrenergic innervation, augmented Noradrenaline (NA), and NA- responsive fibroblasts in the fibrotic lung. These factors interact to drive fibrosis, which can be inhibited via chemical sympathectomy, pharmacologic inhibition of alpha1 adrenergic receptors, or specific deletion of NTN- 1 from macrophages. These findings support the hypothesis that macrophage derived signals such as Netrin-1 foster profibrotic adrenergic nerve remodeling in the lung and will be explored in three aims. This application unites world class investigators in lung biology, scleroderma, innate immunity, adrenergic innervation, Netrin-1, and neuroscience to conduct an integrated project using two animal models, cell specific knockout mice, shielded bone marrow chimeras, pharmacologic receptor activation and inhibition, ex vivo study of human cells and tissues, precision cut lung slices, single cell sequencing approaches, and microCT. Aim 1 will determine the mechanism through which adrenergic nerve derived NA drives pulmonary fibrosis. Aim 2 will determine the mechanism(s) through which Netrin-1+ macrophages regulates pulmonary fibrosis. Aim 3 will define how macrophage derived Netrin-1 controls post-injury adrenergic nerve remodeling. These studies have the potential to produce paradigm shifting results that will change the way we view fibrosis and potentially develop new treatments for SSc-ILD.