This study explored the triggering mechanism of interstitial lung disease (ILD). We established the effects of immunogenic and neurogenic calcitonin gene-related peptide (CGRP) imbalance on the regulation of aquaporin 5 (AQP5) expression and the repair responses that promote the transition from alveolar epithelial cell (AEC) apoptosis to pulmonary fibrosis. Newly diagnosed ILD patients (n = 60) were enrolled, whose serological levels of β-CGRP, α-CGRP, AQP5, receptor activity modifying protein 1, and receptor component protein were detected by ELISA. Th1 and Th2 cytokines and CD4⁺ and CD8⁺ cells were measured by flow cytometry method. In vivo, bleomycin (BLM) was set for modeling pulmonary fibrosis. A CALCA-HET model was set as a chronic pulmonary fibrosis model. Hematoxylin–eosin, immunohistochemistry, and Masson's trichrome staining were performed to assess the role of apoptosis in the injured lung. The concentrations of cytokines were determined by cytokine antibody arrays. Abnormal activation of serological CD4⁺ T lymphocytes and predominant Th2 response was established in the patients with ILD. Moreover, the ratio of β-CGRP/α-CGRP positively correlated with the increased level of AQP5 in patients with ILD. In vivo, a significant increase of AQP5 and β-CGRP at the chronic stage of pulmonary fibrosis was induced by BLM in the mice model, whereas the expression of AQP5 protein was generally lower in the acute alveolitis phase. Moreover, the levels of AQP5 and α-CGRP in the CALCA-HET rats were lower than those of the normal saline group. The high ratio β-CGRP/α-CGRP enhanced the expression of AQP5, inhibited transforming growth factor-β1 (TGFβ1)/P-Smad1/Smad4 pathway, and upregulated the NRF2 signal, whereas the apoptosis of AECs was significantly reduced in late-stage pulmonary fibrosis. The imbalance of β-CGRP/α-CGRP may be associated with the predominance of Th2 response and participate in the process of AEC apoptosis in lung fibrosis. The high ratio of β-CGRP/α-CGRP may elevate the level of AQP5 through inactivation of the TGF-β1/smad1 signaling pathway and upregulation of the Nrf2 signaling in the chronic stage of pulmonary fibrosis.

中文翻译：

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AQP5 的 β-CGRP/α-CGRP 调节失调促进肺泡上皮细胞凋亡向肺纤维化的转变。

本研究探讨了间质性肺病（ILD）的触发机制。我们确定了免疫原性和神经源性降钙素基因相关肽 (CGRP) 失衡对水通道蛋白 5 (AQP5) 表达的调节和促进从肺泡上皮细胞 (AEC) 细胞凋亡向肺纤维化转变的修复反应的影响。入组新诊断的ILD患者（n  =60），ELISA检测β-CGRP、α-CGRP、AQP5、受体活性修饰蛋白1、受体成分蛋白的血清学水平。Th1和Th2细胞因子和CD4 ⁺和CD8 ⁺细胞通过流式细胞术方法测量。在体内，博来霉素 (BLM) 用于模拟肺纤维化。一个CALCA-HET模型被设置为慢性肺纤维化模型。进行苏木精-伊红、免疫组织化学和马森三色染色以评估细胞凋亡在受伤肺中的作用。细胞因子的浓度由细胞因子抗体阵列确定。在 ILD 患者中建立了血清 CD4 ⁺ T 淋巴细胞的异常激活和主要的 Th2 反应。此外，ILD患者β-CGRP/α-CGRP的比值与AQP5水平升高呈正相关。在体内，BLM在小鼠模型中诱导肺纤维化慢性阶段AQP5和β-CGRP的显着增加，而AQP5蛋白的表达在急性肺泡炎阶段普遍较低。此外，AQP5 和 α-CGRP 的水平CALCA- HET大鼠低于生理盐水组。高比例的β-CGRP/α-CGRP增强AQP5的表达，抑制转化生长因子-β1（TGFβ1）/P-Smad1/Smad4通路，上调NRF2信号，而AECs的凋亡在晚期显着减少。肺纤维化阶段。β-CGRP/α-CGRP的失衡可能与Th2反应占优势有关，参与肺纤维化AEC凋亡过程。在肺纤维化的慢性阶段，β-CGRP/α-CGRP 的高比率可能通过 TGF-β1/smad1 信号通路的失活和 Nrf2 信号通路的上调来提高 AQP5 的水平。