Identification of Novel Biomarkers Associated with Corticosteroid Resistance in Asthma by Bioinformatics Analysis and Experimental Validation.

Background: Corticosteroid resistance in asthma, marked by reduced glucocorticoid response, is significantly influenced by cigarette smoke (CS). We sought to explore potential novel biomarkers and therapeutic targets associated with CS-induced corticosteroid resistance in asthma.

Methods: GSE230048 (related to corticosteroid resistance) and GSE13896 (from CS-exposed macrophages) were obtained from GEO. Initially, we performed differential gene expression analysis and weighted gene co-expression network analysis (WGCNA) to discover key genes involved in corticosteroid resistance in asthma. Gene Ontology (GO) term and Kyoto Encyclopedia of Genes and Genomes (KEGG) pathway enrichment analyses were conducted. Receiver operating characteristic (ROC) analysis was used to assess the diagnostic accuracy of these markers. CIBERSORT was applied to clarify immune cell infiltration. Expression of the key biomarker was validated in asthma patients and asthma murine models.

Results: Five overlapping genes upregulated in corticosteroid-resistant asthma patients and smokers' alveolar macrophages were identified. Subsequently, using WGCNA, the most relevant modules were identified and intersected with differentially expressed genes. Tensin 1 (TNS1), ATP-binding cassette subfamily C member 4 (ABCC4), and TNF receptor superfamily member 21 (TNFRSF21) were identified as critical biomarkers for corticosteroid resistance in asthma. ROC analysis showed an AUC of 0.718 for the three-marker combination. Single-cell RNA sequencing confirmed their expression in macrophages from asthmatic patients. Elevated levels of TNS1, ABCC4, TNFRSF21, and M2 macrophage markers (CD301 and CD206) were observed in CS-exposed murine lung tissues and CS condensate-treated Raw264.7 cells. TNS1 knockdown significantly reduced CD301 and CD206 expression, suggesting its role in promoting macrophage M2 polarization.

Conclusion: In conclusion, we identified three hub genes (TNS1, ABCC4, and TNFRSF21) associated with CS-induced corticosteroid resistance in asthma. Additionally, TNS1 may be involved in CS-induced corticosteroid resistance in asthma by promoting macrophage M2 polarization.