Impacto da eferocitose na fagocitose e atividade microbicida via recptores Scavenger em macrófagos alveolares papel de prostaglandina E2
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Data
2013-01-25
Autores
Souza, Taís Picolo de [UNESP]
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Universidade Estadual Paulista (Unesp)
Resumo
Os receptores scavenger (SR) são os principais receptores de reconhecimento padrão (PRR) envolvidos na fagocitose de Streptococcus pneumoniae por macrófagos alveolares (AMs), células estas consideradas a primeira linha de defesa no pulmão. Sabe-se que indivíduos acometidos por doenças pulmonares obstrutivas crônicas (DPOC) são susceptíveis a infecções bacterianas recorrentes e apresentam um intenso acúmulo de células apoptóticas (ACs) no parênquima pulmonar. A hipótese deste estudo fundamenta-se em que o acúmulo de ACs e a fagocitose destas por AMs poderia suprimir as funções efetores destas células, através da liberação de mediadores anti-inflamatórios, tais como TGF- e PGE2. No entanto, nada se sabe quanto aos mecanismos pelos quais PGE2 poderia suprimir esses mecanismos efetores de macrófagos alveolares contra S. pneumoniae, via SR. Nossos resultados demonstram que a presença de ACs promove a inibição da fagocitose e a atividade microbicida de AMs contra S. pneumoniae. A inibição da fagocitose de S. pneumoniae mediada pela eferocitose foi revertida pela inibição da síntese de PGE2 endógena, assim como pelo tratamento com antagonistas deEP2 e pela inibição da enzimaadenililciclase. No entanto, estes efeitos supressores de PGE2 decorrentes da eferocitose por AMs foram independentes da ação de PKA. Desta forma, podemos sugerir que a presença de ACs no pulmão de indivíduos com DPOC poderia desencadear a síntese exacerbada de PGE2 e contribuir na supressão das funções efetoras de AMs contra infecções bacterianas, como S. pneumoniae. Portanto, o tratamento com inibidores da COX, concomitante à terapia antimicrobiana, poderia levar a uma melhora no quadro de imunossupressão desencadeado pela ação de PGE2 no microambiente pulmonar e, portanto, restauração das funções efetoras de AMs
The scavenger receptors (SR) are the major receptors involved in the Streptococcus pneumonia phagocytosis by alveolar macrophages (AMs) that act as the first line of defense in the lung. The increase of susceptibility to bacterial infections has been demonstrated in chronic inflammatory pulmonary disease in which there is an intense accumulation of apoptotic cells (ACs). Our hypothesis is that the uptake of ACs by macrophages could suppress immune responses by releasing anti-inflammatory mediators, such as TGF- and PGE2. However, the way in which PGE2 suppress the effector mechanisms against Streptococcus pneumonia by SR in alveolar macrophages is unclear. We found that the preincubation with AC inhibited the ingestion and killing of S. pneumonia by AMs. The inhibition of S. pneumonia phagocytosis by efferocytosis was partially reverted when endogenous PGE2 production was repressed with a COX inhibitor, EP2 antagonist and likewise with an adenylate cyclase inhibitor. However, this suppressive effect was PKA independent. Moreover, we demonstrated that the inhibition of S. pneumonia phagocytosis by efferocytosis was more pronounced in scavenger receptors class B (SR-B). Thus, we suggest that the presence of ACs in the lungs of patients with COPD could trigger the synthesis of PGE2 and promote the suppression of effector functions of AMs against bacterial infections, such as S. pneumoniae. Therefore, treatment with COX inhibitors, concomitant-microbial therapy, could lead to an improvement in the immunosuppression triggered by the action of PGE2 in the lung microenvironment and thus restoration of effector functions of AMs
The scavenger receptors (SR) are the major receptors involved in the Streptococcus pneumonia phagocytosis by alveolar macrophages (AMs) that act as the first line of defense in the lung. The increase of susceptibility to bacterial infections has been demonstrated in chronic inflammatory pulmonary disease in which there is an intense accumulation of apoptotic cells (ACs). Our hypothesis is that the uptake of ACs by macrophages could suppress immune responses by releasing anti-inflammatory mediators, such as TGF- and PGE2. However, the way in which PGE2 suppress the effector mechanisms against Streptococcus pneumonia by SR in alveolar macrophages is unclear. We found that the preincubation with AC inhibited the ingestion and killing of S. pneumonia by AMs. The inhibition of S. pneumonia phagocytosis by efferocytosis was partially reverted when endogenous PGE2 production was repressed with a COX inhibitor, EP2 antagonist and likewise with an adenylate cyclase inhibitor. However, this suppressive effect was PKA independent. Moreover, we demonstrated that the inhibition of S. pneumonia phagocytosis by efferocytosis was more pronounced in scavenger receptors class B (SR-B). Thus, we suggest that the presence of ACs in the lungs of patients with COPD could trigger the synthesis of PGE2 and promote the suppression of effector functions of AMs against bacterial infections, such as S. pneumoniae. Therefore, treatment with COX inhibitors, concomitant-microbial therapy, could lead to an improvement in the immunosuppression triggered by the action of PGE2 in the lung microenvironment and thus restoration of effector functions of AMs
Descrição
Palavras-chave
Macrofagos, Fagocitose, Pulmões - Doenças, Streptococcus pneumoniae, Alvéolo pulmonar, Macrophages
Como citar
SOUZA, Taís Picolo de. Impacto da eferocitose na fagocitose e atividade microbicida via recptores Scavenger em macrófagos alveolares papel de prostaglandina E2. 2013. 62 f. Dissertação (mestrado) - Universidade Estadual Paulista, Faculdade de Ciências Farmacêuticas, 2013.