Papel funcional do hormônio do crescimento sobre macrófagos peritoneais de camundongos

Abstract

Studies have shown that growth hormone (GH) is a polypeptide with immunomodulatory properties. Herein, studies were performed to determine in vivo and in vitro effects of GH on macrophage by using cultures of resident peritoneal macrophages from swiss mice. The microscopical analyses revealed alterations in the macrophage morphology after GH treatment with 20 and 200 ng/mL for 12 and 24 hours. It was also observed that GH-treated macrophages have an increase in fibronectin and laminin deposition evaluated by indiret immunocytochemistry. By using flow cytometry, it was shown that GH-treatment (200 ng/mL) for 6 and 24 hours altered the Mac-1 and VLA-6 integrins expression on macrophage surface. Moreover, the same GH concentration, during 6 hours of treatment, was able to decreased macrophage adhesion to laminin. In the in vitro migration assays, the GHtreated cells (200 ng/mL) showed opposite effects depending on the treatment time, after 6 hours, there was a increase in migrating cells whereas after 12 hours was a decrease in cell migration. The in vitro GH treatment did not influence the phagocytic activity of macrophages but when the GH treatment was perfomed in vivo, for 7 consecutive days, the peritoneal macrophages from GH-treated mice (20 and 200 μg/kg) showed a higher porcentage of phagocytosis and also a higher phagocytic capacity than cells from control animals. Taken together, these results reinforce the literature data which show that GH can act as an macrophage activating-factor in the immune response.