Influência do hormônio do crescimento nos processos celulares e moleculares da fase inflamatória do reparo tecidual cutâneo

Abstract

In the present study, we investigated in vivo and in vitro the effects of growth hormone (GH) on cellular and molecular processes involved in the inflammatory phase of cutaneous tissue repair in mice. For this purpose, we used 6-month-old male mice of Swiss strain (CEUA / UFAL No. 51/2014). The induction of the wound was performed, after anesthetic administration, with the aid of a 1cm diameter metal ring. Then, the animals were treated with GH (10−7M) for 3 consecutive days, once a day. The control group received only vehicle. The skin fragments were stained with HE for the count of inflammatory cells. Injured skin samples were performed for quantification of cytokines (IL-6, IL-10, TNF-a) involved in inflammatory cellular responses by ELISA. Immunohistochemistry assay was used to evaluate the presence of macrophages and endothelial cells, and the deposition of extracellular matrix molecules: collagen III, fibronectin and laminin. Liver and injured skin fragments were used to evaluate the IGF-1 mRNA expression. In vitro, J774 lineage macrophages and thymic endothelial cells (tEnd.1) were used to evaluate the formation of capillary-like structures in matrigel. Fibroblasts from the 3T3 strain were used for cell migration assay. Initially, the topical treatment with GH for 3 days hás accelerated the recruitment of macrophages and lymphocytes without altering IL-6 levels when compared to control. However, topical use of GH revealed increased levels of IL-10 and decreased levels of TNF-a. In vitro, GH treatment did not alter the IL-6 and IL-10 levels produced by macrophages treated with GH (10−7M). However, GH-treated macrophages conditioned medium stimulated endothelial cells in the formation of capillary-like structures in matrigel. In addition, GH increased the fibroblasts migration. It was further found that topical treatment with GH stimulated angiogenesis, type III collagen deposition of fibronectin and laminin. Finally, gene expression analysis revealed that topical treatment with GH does not alter mRNA levels for IGF-1 in both liver and skin. Taken together, our data suggest that GH accelerates the healing of cutaneous wounds, anticipating macrophage recruitment, increasing the deposition of ECM proteins and stimulating angiogenesis, independent of IGF-1.