Integrating multi-omics and reverse network toxicology to identify pollutant risks and potential intervention targets in pulmonary arterial hypertension.

Background: Idiopathic pulmonary arterial hypertension (PAH) is a progressive cardiovascular disorder with high mortality. Although both genetic and environmental factors are implicated in its pathogenesis, the underlying mechanisms remain unclear. Methods: We integrated transcriptomic data from PAH lung tissue, GWAS summary statistics, and QTL data for DNA methylation, gene expression, and plasma protein. Core dysregulated genes were first identified via differential expression and protein-protein interaction network analysis. Using summary-data-based Mendelian randomization (SMR), we systematically evaluated potential potential genetic associations between methylation, expression, or protein levels of candidate genes and PAH risk, with the HEIDI test to distinguish causality from pleiotropy. Key findings were validated by examining gene expression trends in two independent cohorts. Finally, reverse network toxicology was applied: environmental pollutants targeting identified genes were screened using the CTD, their binding potential assessed via molecular docking, and effects of a candidate pollutant on gene expression and cell proliferation validated Results: We identified 254 differentially expressed genes in PAH. Among these, TAGLN2 exhibited a significant positive association with PAH risk at three molecular levels-DNA methylation, gene expression, and plasma protein, suggesting a pathogenic role. Specifically, increased TAGLN2 protein abundance (HR = 9.00, 95% CI: 1.52-53.16) and gene expression levels (HR = 9.00, 95% CI: 1.52-53.16) were associated with higher PAH risk, while its methylation sites (e.g., cg13892570, cg16107628) showed a negative association. Validation in two independent cohorts confirmed that TAGLN2 expression was upregulated in the lung tissue of PAH patients. Reverse toxicology predicted eight environmental pollutants as potential TAGLN2-targeting agents, including PFOS, dibutyl phthalate, bisphenols, and benzo[a]pyrene. Molecular docking indicated that all these compounds could bind stably to the TAGLN2 protein (binding free energy < -5.0 kcal/mol), with PFOS exhibiting the strongest binding affinity (-8.9 kcal/mol). Conclusion: This study prioritizes TAGLN2 as a genetically associated candidate gene for PAH and identifies environmental pollutants that may target TAGLN2. While the