Elucidating the cellular mechanism for E2-induced dermal fibrosis

Deanna Baker Frost,Adeyemi Ogunleye,Milton Armstrong,Alisa Savchenko,Carol Feghali-Bostwick

doi:10.1186/s13075-021-02441-x

Abstract

BackgroundBoth TGFβ and estradiol (E2), a form of estrogen, are pro-fibrotic in the skin. In the connective tissue disease, systemic sclerosis (SSc), both TGFβ and E2 are likely pathogenic. Yet the regulation of TGFβ in E2-induced dermal fibrosis remains ill-defined. Elucidating those regulatory mechanisms will improve the understanding of fibrotic disease pathogenesis and set the stage for developing potential therapeutics. Using E2-stimulated primary human dermal fibroblasts in vitro and human skin tissue ex vivo, we identified the important regulatory proteins for TGFβ and investigated the extracellular matrix (ECM) components that are directly stimulated by E2-induced TGFβ signaling.MethodsWe used primary human dermal fibroblasts in vitro and human skin tissue ex vivo stimulated with E2 or vehicle (ethanol) to measure TGFβ1 and TGFβ2 levels using quantitative PCR (qPCR). To identify the necessary cell signaling proteins in E2-induced TGFβ1 and TGFβ2 transcription, human dermal fibroblasts were pre-treated with an inhibitor of the extracellular signal-regulated kinase/mitogen-activated protein kinase (ERK/MAPK) pathway, U0126. Finally, human skin tissue ex vivo was pre-treated with SB-431542, a TGFβ receptor inhibitor, and ICI 182,780, an estrogen receptor α (ERα) inhibitor, to establish the effects of TGFβ and ERα signaling on E2-induced collagen 22A1 (Col22A1) transcription.ResultsWe found that expression of TGFβ1, TGFβ2, and Col22A1, a TGFβ-responsive gene, is induced in response to E2 stimulation. Mechanistically, Col22A1 induction was blocked by SB-431542 and ICI 182,780 despite E2 stimulation. Additionally, inhibiting E2-induced ERK/MAPK activation and early growth response 1 (EGR1) transcription prevents the E2-induced increase in TGFβ1 and TGFβ2 transcription and translation.ConclusionsWe conclude that E2-induced dermal fibrosis occurs in part through induction of TGFβ1, 2, and Col22A1, which is regulated through EGR1 and the MAPK pathway. Thus, blocking estrogen signaling and/or production may be a novel therapeutic option in pro-fibrotic diseases.

Highlights

Both TGFβ and estradiol (E2), a form of estrogen, are pro-fibrotic in the skin
Whole exome sequencing of African American patients with systemic sclerosis (SSc) identified collagen 22A1 (Col22A1) as a rare variant that may increase African American. We show that both Transforming growth factor β1 (TGFβ1) and Transforming growth factor β2 (TGFβ2) are induced by E2, as they are in a wound healing model [22, 23], and both likely contribute to dermal fibrosis
We report that E2-induced ERK1/2 phosphorylation in primary human dermal fibroblasts is vital to TGFβ1 and TGFβ2 expression, since blockade of the Mitogen-activated protein kinase (MAPK)/Extracellular signal-regulated kinase (ERK) pathway was inhibitory

Summary

Introduction

In the connective tissue disease, systemic sclerosis (SSc), both TGFβ and E2 are likely pathogenic. The regulation of TGFβ in E2-induced dermal fibrosis remains ill-defined Elucidating those regulatory mechanisms will improve the understanding of fibrotic disease pathogenesis and set the stage for developing potential therapeutics. Mice with a heritable form of pulmonary hypertension that were treated with either an estrogen receptor inhibitor or an aromatase inhibitor showed significant disease improvement [11]. These results imply estrogen is influential in lung fibrosis and its blockade is a conceivable therapeutic target

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