A74-08 Gene Expression Network Analysis Reveals PDIA3-linked UPR-fibrosis Crosstalk Driving Lung Pathophysiology in Influenza-infected Mice

Rationale Viral-fibrotic sequelae remain challenging to manage due to limited biomarkers, therapeutic options, and a lack of understanding of underlying mechanisms. Furthermore, the correlation between post-influenza gene expression and protein interactions with pathophysiology is also unclear. Methods We performed weighted gene co-expression network analysis (WGCNA) on lung transcriptomic data from a time-course influenza infection model in mice. We identified 26 gene modules, 15 of which showed significant correlation with key pathophysiological outcomes, including oxygen saturation (%SpO2) as measured by pulse oximeter readings and collagen deposition as determined by hydroxyproline assay. Results Here, we focused on two gene sets: (a) 462 genes positively correlated with infection and fibrosis but negatively with SpO2, and (b) 220 genes showing the opposite pattern. Functional enrichment, performed using ToppFun application of the ToppGene Suite, revealed that the first set was associated with extracellular matrix organization, collagen metabolism, inflammation, and unfolded protein response (UPR), while the second set was enriched for oxidoreductase activity and lipid metabolism. Our validation studies confirmed dysregulated expression of UPR genes across multiple lung cell types, correlating with worsened pathophysiological responses during and after influenza infection. Notably, inhibition of PDIA3—a UPR-associated gene—downregulated ∼50 transcripts associated with UPR and lung pathophysiological responses. Further, inhibition of PDIA3 significantly decreased Ctss, Fscn1, and C1qb, which also interact with PDIA3 during influenza-induced lung fibrosis. PDIA3 inhibition also reduced disulfide bond formation and secretion of these proteins that contributed to the decrease in influenza-induced pathophysiology and lung fibrosis in mice. Conclusions These results highlight an integrated UPR-related gene expression that correlates with the IAV-induced pathophysiological response, suggesting PDIA3 as a potential therapeutic target.