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-β1 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 (ERα) 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) AE transforming growth factor beta 1 (TGF-β1, 10 ng/mL). ICI 182,780 (ICI, 10 −7 M) or G36 (10 −7 M) were employed as antagonists of ERα or GPR30, respectively. qPCR was employed to determine estrogen receptor-mediated effects of E2 on genes related to fibrosis.Results: ERα 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-β1 significantly increased Smad7 (P = .03) and decreased Col1a1 (P = .04) compared to TGF-β1 alone; this response was negated by the combination of ICI and G36 (P = .009).Conclusions: E2 regulated TGF-β1/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.

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ObjectivesEffective treatments for vocal fold fibrosis remain elusive. Tamoxifen (TAM) is a selective estrogen receptor modulator and was recently reported to have antifibrotic actions. We hypothesized that TAM inhibits vocal fold fibrosis via altered transforming growth factor beta 1 (TGF‐β1) signaling. Both in vitro and in vivo approaches were employed to address this hypothesis.MethodsIn vitro, vocal fold fibroblasts were treated with TAM (10−8 or 10−9 M) ± TGF‐β1 (10 ng/ml) to quantify cell proliferation. The effects of TAM on genes related to fibrosis were quantified via quantitative real‐time polymerase chain reaction. In vivo, rat vocal folds were unilaterally injured, and TAM was administered by oral gavage from pre‐injury day 5 to post‐injury day 7. The rats were randomized into two groups: 0 mg/kg/day (sham) and 50 mg/kg/day (TAM). Histological changes were examined on day 56 to assess tissue architecture.ResultsTAM (10−8 M) did not affect Smad3, Smad7, Acta2, or genes related to extracellular matrix metabolism. TAM (10−8 or 10−9 M) + TGF‐β1, however, significantly increased Smad7 and Has3 expression and decreased Col1a1 and Acta2 expression compared to TGF‐β1 alone. In vivo, TAM significantly increased lamina propria area, hyaluronic acid concentration, and reduced collagen deposition compared to sham treatment.ConclusionsTAM has antifibrotic potential via the regulation of TGF‐β1/Smad signaling in vocal fold injury. These findings provide foundational data to develop innovative therapeutic options for vocal fold fibrosis.Level of EvidenceNA Laryngoscope, 133:2248–2254, 2023