Evaluation of cell damage and modulation of cytokines TNF-α, IL-6 and IL-10 in macrophages exposed to PpIX-mediated photodynamic therapy

Little is known regarding whether photodynamic therapy (PDT)-induced cell death can substantially compromise macrophages (M Phi), which are important cells in PDT-induced immune responses. Here, parameters of PDT-mediated M Phi cytotoxicity and cytokine production in response to protoporphyrin IX (PpIX) were evaluated. Peritoneal M Phi from BALB/c mice were stimulated in vitro with PDT, light, PpIX, or lipopolysaccharide (LPS). After that, cell viability, lipid peroxidation, Nitric Oxide (NO), DNA damage, TNF-alpha, IL-6 and IL-10 were evaluated. Short PDT exposure reduced cell viability by 10-30%. There was a two-fold increase in NO and DNA degradation, despite the non-increase in lipoperoxidation. PDT increased TNF-alpha and IL-10, particularly in the presence of LPS, and decreased the production of IL-6 to 10-fold. PDT causes cellular stress, induces NO radicals and leads to DNA degradation, generating a cytotoxic microenvironment. Furthermore, PDT modulates pro- and anti-inflammatory cytokines in M Phi.