Effect of the estrogen and thyroid hormone on gene and protein expression of RANKL and TNF-± in osteoblastic cells derived from the adipose tissue

Abstract

The osseous tissue shows a considerable metabolic activity that keeps its continuous remodeling, involving a removal of mineralized bone by osteoclasts, followed by the formation of bone matrix by osteoblasts. The regulation of bone remodeling happens by local and systemic factors, that practices its effects about replication of undifferentiated cells, in recruitment and function of bone cells. There is yet another cytokine Tumor Necrosis Factor Alpha (TNF±) may act in the process of osteoclast differentiation, acting directly or indirectly on osteoblasts and/or osteoclasts, may increase bone resorption. Between the local factors are the cytokines Receptor Activator of Nuclear Factor Kappa ² (RANK) and Receptor Activator of Nuclear Factor kappa-B Ligand (RANKL) that take part in differentiation and activation osteoclast. Between the systemic factors that participate in bone remodeling are the thyroid hormones triiodothyronine (T3) and thyroxine (T4) which have much effect on bone resorption and on bone formation and estrogen (E2) that adequate levels in the body assures the removal of cytokines such as RANKL and TNF-±. Based on this, several studies have been made aiming to check a hormonal action on the bone tissue metabolism. One such study is the usage of human osteoblasts, derived from mesenchymal stem cells from adipose tissue. Thus, the culture of osteoblast will allow to evaluate the influence of the T3 and E2 hormones and understand better how the mechanism of osteoclast activation happens. From this experimental model will be possible to clarify important aspects of the T3 supraphysiological and E2 infra-physiologic action on gene and protein expression of RANKL and TNF-± in osteoblasts. (AU)