Abstract
We previously reported that orally administered Clostridium butyricum enhances anti-influenza virus effects through the interferon-λ upregulation in mice lungs; however, the precise mechanism remains unclear. Orally administered C. butyricum promotes the proliferation of Bifidobacterium species in the lung microbiome, and this enhances C. butyricum induced anti-influenza effects. Among the Bifidobacterium species, B. longum effectively enhanced the sensitivity of the lung epithelial cells to long-chain fatty acids through the G-protein-coupled receptor120 upregulation. Oral administration of C. butyricum altered long-chain fatty acid metabolism and promoted interferon-λ production through G-protein-coupled receptor120. We hypothesized that these effects enhance anti-influenza virus responses through interferon-λ upregulation via collaboration between long-chain fatty acid metabolism alterations and the lung microbiome moderation. This study identified a gut-lung axis mechanism and provides insights into viral respiratory infection treatment and prophylaxis.