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

ABSTRACT

Abstract Little is known regarding whether photodynamic therapy (PDT)-induced cell death can substantially compromise macrophages (M), which are important cells in PDT-induced immune responses. Here, parameters of PDT-mediated M cytotoxicity and cytokine production in response to protoporphyrin IX (PpIX) were evaluated. Peritoneal M 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-, IL-6 and IL-10 were evaluated. Short PDT exposure reduced cell viability by 1030%. There was a two-fold increase in NO and DNA degradation, despite the non-increase in lipoperoxidation. PDT increased TNF- 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.

RESUMO

Resumo Pouco se sabe se a morte celular induzida pela terapia fotodinâmica (PDT) compromete os macrófagos (M), envolvidos nas respostas imunes induzidas pela PDT. Neste estudo, foram avaliados parâmetros de citotoxicidade dos M mediada pela PDT e a produção de citocinas, frente à protoporfirina IX (PpIX). M peritoneais de camundongos BALB/c foram estimulados in vitro com PDT, luz, PpIX ou lipopolissacarídeo (LPS). Após isto, a viabilidade celular (VC), a lipoperoxidação, os níveis de óxido nítrico (NO), de DNA degradado, de TNF-, IL-6 e IL-10 foram avaliados. A exposição curta à PDT reduziu a VC em 10-30%. Os níveis de NO e de DNA degradado duplicaram, sem aumento da lipoperoxidação. Houve aumento de TNF- e IL-10, sendo maior na presença de LPS. Já a produção de IL-6 reduziu em dez vezes. A PDT induz estresse celular, gera radicais NO e causa dano ao DNA, tornando o microambiente citotóxico. Ainda, modula citocinas pró e anti-inflamatórias em M.