Transcriptome profiling of peripheral blood for inflammatory subtype classification and diagnostic model construction in asthma

Objective This study aimed to identify inflammatory subtypes of asthma using peripheral blood transcriptomics and to derive candidate biomarkers supported by multi-level validation.Methods This study integrated peripheral blood bulk RNA sequencing (bulk RNA-seq; GSE69683) and single-cell RNA sequencing (GSE172495) data. The bulk RNA-seq dataset was preprocessed using standard procedures, and differentially expressed genes (DEGs) were identified with the limma package, followed by Gene Ontology (GO), Kyoto Encyclopedia of Genes and Genomes (KEGG), and Gene Set Enrichment Analysis (GSEA) enrichment analyses. Weighted Gene Co-expression Network Analysis (WGCNA) was performed to identify inflammation-related gene modules, which were then integrated with DEGs for consensus clustering to define molecular subtypes. Key genes were selected using both Least Absolute Shrinkage and Selection Operator (LASSO) regression and Support Vector Machine–Recursive Feature Elimination (SVM-RFE) algorithms, and their expression patterns were mapped at the single-cell level. Finally, gene expression changes were validated by quantitative real-time PCR (qRT-PCR) in a lipopolysaccharide (LPS)–stimulated inflammatory model of phorbol 12-myristate 13-acetate (PMA)–induced THP-1-derived macrophage-like cells.Results A total of 317 DEGs were enriched in immune-related pathways. WGCNA and consensus clustering identified two molecular subtypes and six key genes (MMP9, NFIL3, STXBP5, OLAH, SRPK1, FAR2). Single-cell profiling mapped these genes to specific immune cells, and qRT-PCR confirmed the upregulation of MMP9 (p < .001) and NFIL3 (p < .01) in inflammatory conditions.Conclusion Peripheral blood transcriptomics may facilitate the classification of asthma inflammatory subtypes, and the identified biomarkers hold potential for noninvasive phenotyping and precision management.