ROTHAN, H.; Mostafa, A.; Bayoumi, M.; Ye, C.; Barre, R.; Allue Guardia, A.; Nogales, A.; Torrelles, J. B.; Martinez-Sobrido, L. B.

Influenza A virus (IAV) pandemics continue to pose serious global health threats, particularly to immunocompromised individuals, children, and the elderly. IAV infections trigger inflammation and tissue damage, promoting lung fibrosis. Unraveling these mechanisms is key to preventing and treating viral-induced pulmonary fibrosis and its lasting impact on respiratory health. Despite available antivirals and vaccines, there is a lack of FDA-approved therapeutics for severe or prolonged IAV pathogenesis. We modeled infection with a recombinant highly pathogenic human A/Texas/37/2024 H5N1 (rHPh-TX H5N1) strain using human airway organoids (HAO) to investigate viral replication, innate immune response, infection-induced fibrogenesis, and therapeutic approaches. The rHPh-TX H5N1 replicated efficiently, triggering a potent interferon (IFN) response and pro-inflammatory cytokine expression in HAO. Prolonged infection led to increased fibroblast-like cells surrounding infected areas, characterized by increased alpha-smooth muscle actin (-SMA) expression and upregulation of transforming growth factor-beta (TGF-{beta}), which caused fibroblast activation and extracellular matrix remodeling. Fibrosis-associated markers (FN, COL1A, COL3A, MMP2, MMP9) were significantly higher than in HAO infected with a pandemic recombinant A/California/04/09 H1N1 (pH1N1). Notably, Rho-associated coiled-coil-forming protein kinase (ROCK) pathway inhibition reduced fibrogenesis, with ROCK1 inhibition proving more effective than ROCK2 inhibition. These findings highlight the potential of targeting ROCK signaling to mitigate IAV-induced lung fibrosis.