Effects of Paeonia-derived Catechin on Neutrophil-associated Inflammation in Pneumonia.

Pneumonia in children is frequently accompanied by excessive inflammatory responses and immune dysregulation, which may lead to severe clinical outcomes. Catechin has shown anti-inflammatory activity in multiple disease settings, but its role and molecular mechanisms in pneumonia remain unclear. Public bulk RNA-sequencing data from pediatric pneumonia (GSE261482) and public mouse lung single-cell RNA-sequencing data from an experimental pneumonia model (GSE295484) were analyzed using weighted gene co-expression network analysis, differential expression analysis, cell-type annotation, and gene set enrichment analysis. Interactions between catechin and selected proteins were assessed using molecular docking and molecular dynamics simulations. A key gene module associated with pneumonia-related traits was identified, and 18 candidate genes, primarily enriched in inflammatory and immune-related pathways, were screened. Single-cell analysis showed that these genes were predominantly enriched in neutrophils and alveolar macrophages, with increased neutrophil proportions under inflammatory conditions. MMP9, PYGL, and GADD45A were selected as candidate genes. Docking and dynamics simulations supported stable predicted interactions between catechin and these selected proteins. Catechin may be associated with pneumonia-related inflammatory pathways by modulating neutrophil-associated pathways and interacting with key immune-related proteins. This study provides a systems-level view of catechin action in pneumonia and highlights potential targets for further experimental validation.