Berberine inhibits Mycoplasma synoviae infection by suppressing PIK3CA-dependent inflammatory and apoptotic responses in avian macrophages

Mycoplasma synoviae (MS) is a widespread avian pathogen that causes respiratory disease and infectious synovitis in poultry, resulting in substantial economic losses. Current control measures are undermined by rising antimicrobial resistance and variable vaccine protection in certain settings, highlighting the need for alternative therapeutic strategies. Berberine (BBR), a natural isoquinoline alkaloid with established antibacterial and immunomodulatory activities, has not been previously investigated in the context of avian mycoplasmosis. Here, we evaluated the therapeutic potential of BBR against MS infection in avian HD11 macrophages. Treatment with BBR at its minimum inhibitory concentration (50 μg/mL) significantly suppressed MS growth and reduced bacterial adhesion to host cells. In parallel, BBR markedly attenuated the MS-induced upregulation of pro-inflammatory cytokines (TNF-α and IL-1β) and decreased apoptosis, as evidenced by reduced caspase-3 and increased Bcl-2 expression. Network pharmacology and molecular docking analyses identified phosphatidylinositol-4,5-bisphosphate 3-kinase catalytic subunit alpha (PIK3CA), the catalytic subunit of PI3K, as a potential molecular target of BBR. Functional validation showed that BBR inhibited the PI3K/Akt signaling axis during infection. Moreover, PIK3CA knockdown recapitulated, whereas its overexpression reversed, the anti-inflammatory and anti-apoptotic effects of BBR. Together, these findings demonstrate that BBR exerts both direct antimicrobial activity and host-directed protective effects against MS infection by targeting PIK3CA-dependent signaling. This study provides mechanistic insight into the therapeutic action of BBR and supports its potential as a novel candidate for the control of MS in poultry.