Mechanisms Underlying the Antifibrotic Potential of Estradiol for Vocal Fold Fibrosis

Objectives/Hypothesis: Vocal fold fibrosis remains a significant clinical challenge. Estrogens, steroid hormones predominantly responsible for secondary sexual characteristics in women, have been shown to alter wound healing and limit fibrosis, but the effects on vocal fold fibrosis are unknown. We sought to elucidate the expression of estrogen receptors and the effects of estrogens on TGF-beta 1 signaling in rat vocal fold fibroblasts (VFFs). Study Design: In vitro. Methods: VFFs were isolated from 10-week-old, male Sprague-Dawley rats, and estrogen receptor alpha (ER alpha) and G protein-coupled receptor 30 (GPR30) were examined via immunostaining and quantitative polymerase chain reaction (qPCR). VFFs were treated with estradiol (E2, 10(-7), 10(-8) or 10(-9) M) +/- transforming growth factor beta 1 (TGF-beta 1, 10 ng/mL). ethylenediaminetetraacetic acid (ICI) 182,780 (ICI, 10(-7) M) or G36 (10(-7) M) were employed as antagonists of ER alpha or GPR30, respectively. qPCR was employed to determine estrogen receptor-mediated effects of E2 on genes related to fibrosis. Results: ER alpha and GPR30 were expressed in VFFs at both the protein and the mRNA levels. E2 (10(-7) M) did not alter Smad3, Smad7, Acta2 mRNA, or extracellular matrix related genes. However, the combination of E2 (10(-8) M) and TGF-beta 1 significantly increased Smad7 (P = .03) and decreased Col1a1 (P = .04) compared to TGF-beta 1 alone; this response was negated by the combination of ICI and G36 (P = .009). Conclusions: E2 regulated TGF-beta 1/Smad signaling via estrogen receptors in VFFs. These findings provide insight into potential mechanisms of estrogens on vocal fold injury with the goal of enhanced therapeutics for vocal fold fibrosis.

Automated summary

This study examined the expression of estrogen receptors in vocal fold fibroblasts and the effects of estrogens on TGF-beta 1 signaling. The results showed that E2 can regulate TGF-beta 1/Smad signaling through estrogen receptors in VFFs, providing insight into potential mechanisms for therapeutic strategies in vocal fold fibrosis.