Study of SMAD-Dependent Signal Pathway in the Development of Early Pulmonary Fibrosis in Mice Infected with Influenza A/H1N1 Virus

Early fibrosis of the visceral organs is one of the main complications of infection caused by influenza A virus. Structural manifestations and molecular regulators of the epithelialmesenchymal transformation as a possible mechanism of fibrosis progression were studied in mice infected with influenza A/H1N1 A/Tomsk/13/2010 virus. We found early fibrosis of the lungs against the background of minor changes in fibroblast count. However, enhanced expression of TGF-β and SMAD-2 by macrophages and alveolocytes attested to possible development of epithelial-mesenchymal transformation and its contribution to activation of fibrogenesis process in the lungs.