Study of the Role and Mechanism of MSLN in Idiopathic Pulmonary Fibrosis

Abstract Background: Idiopathic pulmonary fibrosis (IPF) is a chronic interstitial lung disease marked by insidious onset, complex etiology, rapid progression, and poor prognosis. The disease's typical pathological features primarily begin in the proximal pleura of the lower lungs, where persistent extracellular matrix deposition at fibrosis sites leads to abnormal alveolar remodeling and scarring in lung tissues, progressively extending into the lung parenchyma and ultimately causing irreversible lung damage. Although IPF has distinct spatiotemporal characteristics, the underlying mechanisms remain unclear. Mesothelin (MSLN), an important regulatory protein in pleural diseases, has been widely studied in fibrotic diseases. Studies in biliary stasis hepatic fibrosis suggest that MSLN deficiency can improve fibrosis in the liver, lungs, and kidneys in mice; however, the role and clinical relevance of MSLN in pulmonary fibrosis have yet to be fully investigated. Methods: This study included 63 patients with IPF and 33 healthy controls. Clinical data (e.g., age, BMI, blood work, lung function) and HRCT imaging were analyzed to assess fibrosis extent, and MSLN expression levels in peripheral blood were measured. In a murine model of bleomycin-induced pulmonary fibrosis, an MSLN-neutralizing antibody (2 mg/kg) was administered to examine weight changes and fibrosis alleviation using QPCR, immunohistochemistry, pathological staining, and immunofluorescence. Single-cell sequencing and transcriptomics were conducted to analyze the effects of MSLN on alveolar type II (ATII) cell senescence, differentiation phenotypes, and pathogenic fibroblasts. The therapeutic effects of MSLN intervention were also evaluated using in vitro human lung tissue. Results: Univariate regression analysis identified MSLN, FVC, DLCO-SB, total leukocyte count, and neutrophil count as IPF influencing factors, and multivariate regression indicated that MSLN could serve as an independent risk factor for IPF. Correlation analysis showed a significant negative correlation between peripheral blood MSLN expression and FVC and DLCO-SB in IPF patients. Animal experiments confirmed that bleomycin-induced fibrotic mice exhibited a marked increase in transitional ATII cells with a typical senescence phenotype. In vivo MSLN-neutralizing antibody intervention partially alleviated fibrosis symptoms in model mice, reducing differentiation-impaired ATII cells. Single-cell sequencing further supported these findings, indicating a significant reduction in pathological fibroblasts after MSLN-neutralizing antibody intervention in fibrotic model mice. In vitro assays confirmed these therapeutic effects on human lung tissue. Conclusion: MSLN is significantly associated with IPF prognosis, and targeted MSLN intervention may reduce fibrosis in a bleomycin-induced mouse model by decreasing senescent ATII cells and pathological fibroblasts. These findings suggest that MSLN may serve as a potential therapeutic target for IPF.