Integrated Bioinformatics Analysis and In Vitro Evidence Support HSP90AA1 as a Candidate Target of Camellia petelotii (Merr.) Sealy in Pulmonary Arterial Hypertension

Pulmonary arterial hypertension (PAH) is a severe and progressive cardiopulmonary disorder with limited treatment options. Camellia petelotii (Merr.) Sealy (CP) contains multiple flavonoids and other phytochemicals, but its active compounds and molecular mechanisms in PAH remain unclear. Active compounds of CP were screened by comprehensive literature mining and absorption, distribution, metabolism, and excretion (ADME) evaluation. PAH-related hub targets were identified from transcriptomic data using weighted gene co-expression network analysis (WGCNA), machine learning, and external validation. Functional enrichment, immune infiltration, and single-cell RNA-sequencing analyses were performed to characterize their biological roles and cellular localization. Molecular docking and molecular dynamics simulations assessed compound–target interactions. The effects of CP were further evaluated in hypoxia-induced rat pulmonary artery smooth muscle cells (RPASMCs). Five core bioactive compounds were identified, among which luteolin and quercetin were prioritized for further analysis. HSP90AA1 and ROCK2 were screened as hub targets. Bioinformatic analyses suggested that these targets were mainly associated with the “Lipid and atherosclerosis” pathway, metabolic reprogramming, and modulation of the immune microenvironment. Single-cell analysis showed broad expression of HSP90AA1 and enrichment of ROCK2 in fibroblasts and endothelial cells. Molecular docking and molecular dynamics simulations supported stable binding of luteolin to HSP90AA1. In vitro, CP extract inhibited hypoxia-induced hyperproliferation of RPASMCs and reduced HSP90AA1 protein expression. HSP90AA1 may represent a candidate molecular mediator of CP in PAH, and CP inhibited hypoxia-induced RPASMC proliferation in association with downregulation of HSP90AA1.