D21-22 Asthma Status Programs Both the Epigenetic and Transcriptional Responses to Influenza a Virus

Abstract Rationale Viral respiratory infections, including influenza A virus (IAV), are major triggers of asthma exacerbations. The airway epithelium serves as both a physical barrier and an active immune interface, coordinating antiviral and inflammatory responses that determine infection outcomes. These responses are governed by complex molecular mechanisms modulated by the epigenetic state of epithelial cells. In individuals with asthma, distinct airway epithelial DNA methylation signatures have been reported in genes regulating these processes, which may contribute to aberrant responses during viral infection. Among host factors that modulate epithelial immunity, surfactant protein A (SP-A) is known to reduce viral replication and modulate immune signaling. We hypothesized that SP-A reverses asthma-related epigenetic changes driven by type 2 inflammation and previous viral infections. Methods Primary bronchial epithelial cells were obtained via research bronchoscopy (endobronchial brushing) from type 2 asthmatic and non-asthmatic individuals. Passage-2 cells were differentiated at ALI for 21 days and then treated with vehicle or SP-A (100 µg/mL) for four hours followed by mock or IAV infection (100 pfu/well) for two hours. Using paired genomic DNA and RNA extracted from the same TRIzol sample of bronchial epithelial cultures, we performed genome-wide DNA methylation profiling with the Illumina EPIC v2 array in parallel with bulk RNAseq, directly linking epigenetic and transcriptional responses to IAV infection in asthmatic and non-asthmatic individuals. Results DNA methylation analysis of the top 1000 differentially methylated positions (IAV-infected vs uninfected) revealed that non-asthma samples were enriched for response to virus (Gene Ontology (GO):0009615, FDR = 9.0 × 10−5), whereas asthma samples were enriched for response to cytokine (GO:0034097, FDR = 5.9 × 10−³). Furthermore, in asthmatic cells, enrichment for response to virus (GO:0009615) emerged only after SP-A treatment (FDR = 1.0 × 10-4), suggesting that SP-A actively reprograms the otherwise diminished antiviral response in asthma. Bulk RNAseq showed striking concordance: among the top 20 differentially expressed genes (|log2FC| 0.5, FDR 0.05) in non-asthma samples only, the largest protein-protein interaction network contained 11 proteins, 9 involved in the viral response, with response to virus (GO:0009615, FDR = 2.8 × 10-7) as the most enriched process; in asthma samples, a comparable network did not form, and instead response to cytokine (GO:0034097, FDR = 0.04) was enriched. Conclusions Our paired epigenomic-transcriptomic approach demonstrated a consistent pattern across epigenome and transcriptome, and suggests that distinct epigenetic programming in asthma may drive the attenuated antiviral and heightened pro-inflammatory transcriptional responses, which may be reversed by exogenous SP-A. This abstract is funded by: National Institute of Health grant NIAID U19125357