ALA-PDT induces ferroptosis in HPV-infected cells and promotes M1 macrophage polarization.

Condyloma acuminatum (CA) is a recurrent human papillomavirus (HPV)-associated lesion characterized by a locally immunosuppressive microenvironment. Although 5-aminolevulinic acid-mediated photodynamic therapy (ALA-PDT) has been used as a local treatment option for CA and other HPV-related lesions, the mechanisms underlying its immunomodulatory effects remain incompletely understood. In this study, we investigated whether ALA-PDT-induced ferroptosis is associated with macrophage polarization and immune microenvironment-related changes in experimental CA models. HPV16-positive SiHa cells were used as an HPV-positive epithelial cell model to examine the cellular response to ALA-PDT, and the findings were further validated in an ex vivo CA tissue culture model. ALA-PDT significantly reduced the long-term clonogenic growth of SiHa cells in vitro, as demonstrated by colony formation assays. Mechanistically, ALA-PDT suppressed the GPX4/SLC7A11 antioxidant system and increased the accumulation of reactive oxygen species, malondialdehyde, and lipid peroxides in SiHa cells, indicating ferroptosis-associated cellular changes. In a Transwell co-culture system, ALA-PDT-treated SiHa cells promoted macrophage polarization toward an M1-like phenotype, as indicated by increased expression of CD86, iNOS, and IL-1β and decreased expression of CD206 and CD163. These effects were partially attenuated by ferrostatin-1. Consistently, ALA‑PDT reduced GPX4 and SLC7A11 expression in ex vivo condyloma acuminatum tissues, concomitant with an increase in CD86‑positive macrophages and a decrease in CD206‑positive macrophages. Collectively, these findings suggest that ALA-PDT suppress clonogenic growth, induce ferroptosis-associated changes, and modulate macrophage polarization in experimental CA-related models. Further studies are required to determine whether these effects contribute to lesion clearance and therapeutic responses in vivo.