Mechanisms mediating the pro-fibrotic effects of estradiol

Abstract

Scleroderma is a connective tissue disease which promotes fibrosis of the skin and internal organs. Scleroderma patients have upregulated production of fibrotic extracellular matrix proteins and upregulated serum estradiol levels compared to control subjects. Estradiol effects eukaryotic transcription and gene expression when it enters the nucleus via one of its nuclear hormone receptors. Estrogen receptor one/ estrogen receptor alpha (ESR1) is present on the nuclear membrane and binds the ligand estrogen. These experiments were designed to study the various isoforms of ESR1 and determine if gene expression of ESR1 was greater in fibroblasts and human skin stimulated with estradiol than vehicle treated fibroblasts and human skin. An additional goal was to compare gene expression and protein production in estradiol and vehicle treated fibroblasts. Human skin was cultured and treated to create both in vitro and ex vivo models. RNA harvested from the fibroblasts of both models was used to make cDNA and run real-time PCR (qPCR) to determine gene expression within the cells when treated with estradiol or ethanol which served as the control treatment. Cell lines (n = 5) were studied for in vitro and ex vivo experiments. The qPCR data showed that dermal fibroblasts in vitro showed an increase in ESR1 at 30 minutes during the short time course and at 96 hours after stimulation. The ex vivo in organ culture stimulated with estradiol showed an increase in ESR1 at both 48 and 72 hours after stimulation. The western blot data showed an increase in nuclear localization of ESR1 in the nuclear membrane and chromatin but not in the cytosol or cellular membrane when cells were treated with estradiol. Therefore, it was concluded that increased levels of serum estradiol, which occurs in patients with scleroderma, have increased transcription and translation of ESR1 in addition to the increased production of fibronectin and collagen1A1.