Evaluation of cell damage and modulation of cytokines TNF-α, IL-6 and IL-10 in macrophages exposed to PpIX-mediated photodynamic therapy / Avaliação do dano celular e da modulação das citocinas TNF-α, IL-6 e IL-10 em macrófagos expostos à terapia fotodinâmica mediada pela PpIX

Abstract Little is known regarding whether photodynamic therapy (PDT)-induced cell death can substantially compromise macrophages (MΦ), which are important cells in PDT-induced immune responses. Here, parameters of PDT-mediated MΦ cytotoxicity and cytokine production in response to protoporphyrin IX (PpIX) were evaluated. Peritoneal MΦ 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-α, 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-α 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 MΦ.

Resumo Pouco se sabe se a morte celular induzida pela terapia fotodinâmica (PDT) compromete os macrófagos (MΦ), envolvidos nas respostas imunes induzidas pela PDT. Neste estudo, foram avaliados parâmetros de citotoxicidade dos MΦ mediada pela PDT e a produção de citocinas, frente à protoporfirina IX (PpIX). MΦ 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-α, 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-α 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 MΦ.

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

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 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.

Toluene permeabilization differentially affects F- and P-type ATPase activities present in the plasma membrane of Streptococcus mutans

Streptococcus mutans membrane-bound P- and F-type ATPases are responsible for H+ extrusion from the cytoplasm thus keeping intracellular pH appropriate for cell metabolism. Toluene-permeabilized bacterial cells have long been used to study total membrane-bound ATPase activity, and to compare the properties of ATPase in situ with those in membrane-rich fractions. The aim of the present research was to determine if toluene permeabilization can significantly modify the activity of membrane-bound ATPase of both F-type and P-type. ATPase activity was assayed discontinuously by measuring phosphate release from ATP as substrate. Treatment of S. mutans membrane fractions with toluene reduced total ATPase activity by approximately 80 percent and did not allow differentiation between F- and P-type ATPase activities by use of the standard inhibitors vanadate (3 µM) and oligomycin (4 µg/mL). Transmission electron microscopy shows that, after S. mutans cells permeabilization with toluene, bacterial cell wall and plasma membrane are severely injured, causing cytoplasmic leakage. As a consequence, loss of cell viability and disruption of H+ extrusion were observed. These data suggest that treatment of S. mutans with toluene is an efficient method for cell disruption, but care should be taken in the interpretation of ATPase activity when toluene-permeabilized cells are used, because results may not reflect the real P- and F-type ATPase activities present in intact cell membranes. The mild conditions used for the preparation of membrane fractions may be more suitable to study specific ATPase activity in the presence of biological agents, since this method preserves ATPase selectivity for standard inhibitors.