背景:慢性阻塞性肺疾病(COPD),慢性炎症性肺病,是全球发病率和死亡率的主要原因。长期吸烟(CS)导致不可逆的气道重塑并显着降低肺功能是COPD的主要危险因素。角蛋白15+(Krt15+)细胞具有自我更新和分化的潜能,扩散,和气道基底细胞的分化;然而,Krt15在COPD中的作用尚不清楚。
方法:将Krt15敲除(Krt15-/-)和野生型(WT)C57BL/6背景小鼠暴露于CS6个月以建立COPD模型。Krt15-CrePGR;Rosa26-LSL-td番茄小鼠用于追踪Krt15+细胞的命运。进行苏木精和伊红(H&E)和Masson染色以评估组织病理学和纤维化,分别。此外,慢病毒递送的短发夹RNA(shRNA)用于敲低用香烟烟雾提取物(CSE)刺激的人支气管上皮(HBE)细胞中的KRT15。使用蛋白质印迹评估蛋白质表达,免疫组织化学,和酶联免疫吸附测定。
结果:Krt15-/-CS小鼠出现严重的炎症细胞浸润,气道重塑,还有肺气肿.此外,Krt15敲除加重CS诱导的基质金属蛋白酶-9(MMP-9)分泌和上皮间质转化(EMT),这被SB-3CT逆转了,MMP-9抑制剂。与这一发现一致,KRT15敲低促进MMP-9表达和体外EMT进展。此外,支气管上皮细胞中Krt15+细胞逐步增多并转化为肺泡Ⅱ型(AT2)细胞。
结论:Krt15通过促进MMP-9表达调节EMT过程,保护肺组织免受CS诱导的损伤,炎性浸润,和凋亡。此外,Krt15+细胞转化为AT2细胞保护肺泡。这些结果表明Krt15是COPD的潜在治疗靶点。
BACKGROUND: Chronic obstructive pulmonary disease (COPD), a chronic inflammatory lung disease, is a leading cause of morbidity and mortality worldwide. Prolonged cigarette smoking (CS) that causes irreversible airway remodeling and significantly reduces lung function is a major risk factor for COPD. Keratin15+ (Krt15+) cells with the potential of self-renewal and differentiation properties have been implicated in the maintenance, proliferation, and differentiation of airway basal cells; however, the role of Krt15 in COPD is not clear.
METHODS: Krt15 knockout (Krt15-/-) and wild-type (WT) mice of C57BL/6 background were exposed to CS for six months to establish COPD models. Krt15-CrePGR;Rosa26-LSL-tdTomato mice were used to trace the fate of the Krt15+ cells. Hematoxylin and eosin (H&E) and Masson stainings were performed to assess histopathology and fibrosis, respectively. Furthermore, lentivirus-delivered short hairpin RNA (shRNA) was used to knock down KRT15 in human bronchial epithelial (HBE) cells stimulated with cigarette smoke extract (CSE). The protein expression was assessed using western blot, immunohistochemistry, and enzyme-linked immunosorbent assay.
RESULTS: Krt15-/- CS mice developed severe inflammatory cell infiltration, airway remodeling, and emphysema. Moreover, Krt15 knockout aggravated CS-induced secretion of matrix metalloproteinase-9 (MMP-9) and epithelial-mesenchymal transformation (EMT), which was reversed by SB-3CT, an MMP-9 inhibitor. Consistent with this finding, KRT15 knockdown promoted MMP-9 expression and EMT progression in vitro. Furthermore, Krt15+ cells gradually increased in the bronchial epithelial cells and were transformed into alveolar type II (AT2) cells.
CONCLUSIONS: Krt15 regulates the EMT process by promoting MMP-9 expression and protects the lung tissue from CS-induced injury, inflammatory infiltration, and apoptosis. Furthermore, Krt15+ cells transformed into AT2 cells to protect alveoli. These results suggest Krt15 as a potential therapeutic target for COPD.