Análise imunoistoquímica após terapia fotodinâmica com cloro-alumínio ftalocianina em tecidos gengivais de humanos / Immunohistochemical analyzes after photodynamic therapy with chloro-aluminum phthalocyanine in human gingival tissues

Embora a terapia fotodinâmica venha sendo utilizada como uma ferramenta útil nos últimos 30 anos em oncologia, poucos estudos clínicos em odontologia têm sido conduzidos. A terapia fotodinâmica (TFD) utiliza fotossensibilizantes atóxicos e seletivos que são administrados nas células alvo seguida de aplicação local de luz visível, produzindo espécies reativas de oxigênio capazes de ocasionar morte celular por apoptose ou necrose, de afetar a vascularidade local, além de exercer importantes efeitos no sistema imune. Novas gerações de fármacos fotossensibilizantes, como as ftalocianinas nanoparticuladas tem apresentado excelentes resultados na atividade antitumoral e antibacteriana. Neste contexto, o presente trabalho realizou o primeiro protocolo clínico de aplicação local da nanoemulsão de cloroalumínio ftalocianina (AlClFc) seguida de irradiação em gengiva de humanos, e analisou descritiva e comparativamente, por meio de imunoistoquímica, a expressão de RANK, RANKL, OPG e VEGF em um modelo split-mouth. Oito voluntários saudáveis com indicação clínica de exodontia foram incluídos no estudo. Sete dias antes da exodontia, foi aplicado na gengiva dos participantes, 5µM de nanoemulsão de AlClFc seguida de irradiação com laser diodo (660nm, 7J/cm2), o lado contralateral foi utilizado como controle. Os espécimes teciduais foram removidos sete dias após a TFD e subdivididos em dois grupos (grupo teste e grupo controle) para análise histológica e imunoistoquímica. Os pacientes foram monitorados no dia aplicação, 7, 14 e 30 dias após a terapia para avaliação de efeitos adversos da terapia. Alterações vasculares foram observadas nas amostras gengivais que receberam a TFD. Áreas de edema e congestão vascular, além de intensa vascularização foram visualizadas. Adicionalmente, focos de calcificação distrófica em região subepitelial foram visualizados nos espécimes do grupo teste. Os resultados demonstraram um padrão similar dos escores de imunomarcação de RANK, RANKL e VEGF entre os grupos teste e controle, não havendo diferença estatística significante (p=0.317, p=0.777, p=0.814, respectivamente). RANK e RANKL exibiram imunomarcação fraca ou ausente na maioria dos espécimes analisados. Não houve imunomarcação para a OPG. O VEGF mostrou imunomarcação moderada a forte nos espécimes do grupo teste. Adicionalmente, o estudo clínico mostrou que a terapia foi bem tolerada por todos os pacientes. Os efeitos adversos foram de curta duração e totalmente reversíveis. Tomados em conjunto, os resultados apresentados neste estudo mostraram que o protocolo utilizado por nós, mediado por nanoemulsão contendo AlClFc, é seguro para aplicação clínica em tecido gengival e, sugerem uma forte imunomarcação para o VEGF após a terapia. (AU)

Although photodynamic therapy have been used as a useful tool over the past 30 years in oncology, few clinical trials have been conducted in dentistry. Photodynamic therapy (PDT) uses non-toxic photosensitizers and selective which are administered in target cells followed by local application of visible light, producing reactive oxygen species capable of causing cell death by apoptosis or necrosis, injured the local vasculature, and exert important effects on the immune system. New generations of photosensitizing agents, such as nanoparticulate phthalocyanines, has shown excellent results in antitumor and antibacterial activity . In this context, the present work constitutes the first clinical protocol of local application of nanoemulsion chloro-aluminum phthalocyanine (AlClFc) followed by irradiation in human gingiva, and analyzed descriptively and comparatively , by means of immunohistochemistry , the expression of RANK , RANKL , OPG and VEGF in a split -mouth model. Eight healthy volunteers with clinical indication for extraction were included in the study . Seven days before the extraction, was injected in the gingiva of participants, 5µM of nanoemulsion AlClFc followed by irradiation with diode laser (660nm, 7J/cm2 ), the contralateral side was used as control. Tissue specimens were removed seven days after the TFD is performed. Tissues sample were divided into two groups (test and control groups) for histological and immunohistochemical analysis. Patients were monitored at days, 0, 7, 14 and 30 to assess adverse effects of the therapy. Vascular alterations were seen in gingival samples that received PDT. Areas of edema and vascular congestion, and intense vascularization were viewed . Additionally, dystrophic calcification in subepithelial region were observed in the test group. The results showed a similar pattern of immunostaining scores of RANK, RANKL and VEGF between the test and control groups, with no statistically significant difference (p = 0.317, p = 0.777, p = 0.814, respectively). RANK and RANKL exhibited weak or absent immunostaining in most specimens analyzed. There was no immunostaining for OPG. VEGF showed moderate to strong immunostaining in specimens from the test group. In addition, the clinical study showed that therapy was well tolerated by all patients. Adverse effects were short-time and completely reversible. Taken together, the results presented in this study showed that PDT mediated by nanoemulsion containing AlClPc is safe for clinical application in gingival tissue and suggests that a strong immunostaining for VEGF after therapy. (AU)

Porphyromonas gingivalis decreases osteoblast proliferation through IL-6-RANKL/OPG and MMP-9/TIMPs pathways.

Background: Porphyromonas gingivalis, an important periodontal pathogen, is closely associated with inflammatory alveolar bone resorption. This bacterium exerts its pathogenic effect indirectly through multiple virulence factors, such as lipopolysaccharides, fimbriae, and proteases. Another possible pathogenic path may be through a direct interaction with the host's soft and hard tissues (e.g., alveolar bone), which could lead to periodontitis. Aims and Objectives: The aim of the present study was to investigate the direct effect of live and heat-inactivated P gingivalis on bone resorption, using an in vitro osteoblast culture model. Results: Optical microscopy and 3-[4,5-dimethylthiazol-2-yl]-2,5-diphenyl-tetrazolium bromide MTT assay revealed that live P gingivalis induced osteoblast detachment and reduced their proliferation. This effect was specific to live bacteria and was dependent on their concentration. Live P gingivalis increased IL-6 mRNA expression and protein production and downregulated RANKL and OPG mRNA expression. The effect of live P gingivalis on bone resorption was strengthened by an increase in MMP-9 expression and its activity. This increase was accompanied by an increase in TIMP-1 and TIMP-2 mRNA expression and protein production by osteoblasts infected with live P gingivalis. Conclusion: Overall, the results suggest that direct contact of P gingivalis with osteoblasts induces bone resorption through an inflammatory pathway that involves IL-6, RANKL/OPG, and MMP-9/TIMPs.