RESUMO
The clearance of apoptotic cells by phagocytes is a fundamental process during tissue remodeling and resolution of inflammation. In turn, the phagocytosis of apoptotic cells generates signals that suppress pro-inflammatory activation of macrophages. These events occur during the resolution phase of inflammation and therefore the malfunctioning of this process may lead to inflammation-related tissue damage. Here, we demonstrate that the calcium-binding protein S100A9, normally abundant in the cytoplasm of neutrophils and also released by apoptotic neutrophils, is involved in the suppression of macrophages after the uptake of apoptotic neutrophils. Both, spontaneous and induced production of inflammatory species (nitric oxide, hydrogen peroxide and TNF-alpha) as well as the phagocytic activity were inhibited when macrophages were in presence of apoptotic neutrophils, conditioned medium from neutrophil cultures or a peptide corresponding to the C-terminal region of S100A9 protein. On the other hand, macrophages kept in the conditioned medium of neutrophils that was previously depleted of S100A9 were shown to resume the activated status. Finally, we demonstrate that the calcium-binding property of S100A9 might play a role in the suppression process, since the stimulation of intracellular calcium release with ionomycin significantly reversed the effects of the uptake of apoptotic neutrophils in macrophages. In conclusion, we propose that S100A9 is a novel component of the regulatory mechanisms of inflammation, acting side-by-side with other suppressor factors generated upon ingestion of apoptotic cells.
Assuntos
Calgranulina B/imunologia , Macrófagos Peritoneais/imunologia , Neutrófilos/imunologia , Fagocitose , Animais , Apoptose/imunologia , Células Cultivadas , Técnicas de Cocultura , Regulação para Baixo , Inflamação/imunologia , CamundongosRESUMO
OBJECTIVE AND DESIGN: In the present study, the effect of a synthetic peptide (H(92)-G(102)) identical to the C-terminus of murine S100A9 (mS100A9p) was investigated on adherent peritoneal cell function. MATERIALS AND METHODS: For in vitro assays, peritoneal cells were obtained from the abdominal cavity of mice and incubated, with the different concentrations of mS100A9p, for 1 h, and then their spreading and phagocytosis activities were evaluated. For ex-vivo assays, cells obtained from animals treated for 1 h with the peptide were submitted to the mannose-receptor phagocytosis assay. Shorter homologue peptides to the C-terminus of mS100A9p were also evaluated on in vitro phagocytosis assays of Candida albicans particles. RESULTS: mS100A9p reduced both the spreading index and phagocytic activity, in vitro and ex-vivo, independent of the receptor evaluated. The homologue peptide corresponding to the H(92)-E(97) region of mS100A9p, the zinc-binding motif, was responsible for such an effect. CONCLUSION: These results suggest a modulator effect of the C-terminus of S100A9 protein on the function of adherent peritoneal cells.
Assuntos
Calgranulina B/química , Ativação de Macrófagos , Peritônio/citologia , Motivos de Aminoácidos , Animais , Calgranulina B/metabolismo , Candida albicans/metabolismo , Adesão Celular , Células Cultivadas , Relação Dose-Resposta a Droga , Eritrócitos/citologia , Eritrócitos/microbiologia , Macrófagos Peritoneais/citologia , Masculino , Camundongos , Peptídeos/química , Fagocitose , Ligação Proteica , Estrutura Terciária de Proteína , Ovinos , Zinco/químicaRESUMO
Macrophages secrete a variety of chemical mediators that play a central role in the pathophysiology of inflammatory pain. Therefore, the activation or deactivation of these cells in an inflammatory focus could modulate the intensity of the algogenic response. Based on these premises and on our previous demonstration that the calcium-binding protein MRP-14, highly expressed in neutrophils, deactivates activated macrophages in vitro, we decided to investigate the role of MRP-14 and of neutrophils in the control of inflammatory pain in mice. Our results show that this protein is endowed with antinociceptive activity. When tested in the writhing model it was able to inhibit pain response but did not change the behavior of the animals in the hot plate test. This observation indicates that MRP-14 down-regulates inflammatory but not central pain. Using a model of acute neutrophilic peritonitis induced by glycogen, a close correlation between neutrophil migration and antinociception was detected. Surgical adrenalectomy demonstrated that the antinociceptive response induced by glycogen was not due to endogenous liberation of glucocorticoids. The treatment of animals either with a monoclonal antibody anti-MRP-14 or a monoclonal antibody that depletes the animals of neutrophils reverts the antinociceptive response observed in the glycogen-induced peritonitis. These data define the calcium-binding protein MRP-14 as a novel mediator for the control of inflammatory pain and consequently discloses an anti-inflammatory role for the neutrophil.