Host transcriptomic analysis reveals a defective intracellular environment that limits SARS-CoV-2 replication in...

Cystic fibrosis (CF) is characterized by chronic airway inflammation, yet clinical observations have revealed more favorable COVID-19 outcomes than originally predicted. Several studies demonstrated a significant decrease of SARS-CoV-2 replication in CF-mutated bronchial cells suggesting that CFTR dysfunction may interfere with viral replication, though the underlying mechanisms remain unclear. To elucidate these mechanisms we performed transcriptomic profiling of SARS-CoV-2-infected bronchial epithelial cells with wild-type (WT) or mutated CFTR, using both immortalized and primary airway models. RNA-seq was performed on WT and CF cellular models before and at 24, 48, and 72-hours post-infection. The differentially expressed genes (DEGs) were defined as genes with a log2 fold change>1 between groups (p<0.05) and significant DEGs were subjected to Gene Ontology and KEGG enrichment analysis (p<0.05). Our results reveal that CFTR deficiency impairs SARS-CoV-2 replication not by altering receptor availability (e.g., ACE2, TMPRSS2), but through widespread intracellular remodeling defects. CF cells failed to activate key antiviral and inflammatory responses, including interferon signaling, AP-1 transcriptional complex, and IL-6-mediated pathways. Furthermore, they exhibited defective unfolded protein response, altered calcium signaling, and disrupted ER-mitochondrial communication. Crucially, pH dysregulation and impaired expression of V-ATPase subunits and autophagy-related genes hindered vesicle acidification, double-membrane vesicle formation, and viral assembly. These intrinsic alterations also blunted virus-induced senescence programs. Collectively, our findings indicate that CF cellular environment is intrinsically unfavorable to SARS-CoV-2, limiting its replication and propagation. This study provides a mechanistic basis for the reduced viral burden observed in CF and highlights intracellular pH regulation and organelle homeostasis as potential therapeutic targets against SARS-CoV-2 infection.