Delineating Effects of Stress-Analogous, Low-Dose Cortisol Exposure on Human Vocal Fold Fibroblasts.

OBJECTIVE: Psychosocial stress results in an increase of circulating glucocorticoids in blood plasma that flows throughout the body. It is unclear whether stress-induced glucocorticoid exposure alters biological mechanisms of human vocal fold fibroblasts (hVFF). This study delineated the effects of stress-analogous cortisol exposure (100 nM) on healthy hVFF and lipopolysaccharide (LPS)-treated hVFF, in vitro. METHODS: We exposed hVFF to four conditions - cortisol-treated (100 nM, 7 days), LPS-treated, combined cortisol + LPS-treated, and an untreated control. Relative gene expression of inflammatory (IL1-β, TNF-α, transforming growth factor [TGF]-β1), glucocorticoid signaling (11β HSD1, glucocorticoid-induced leucine zipper [GILZ]), and fibrotic gene expression (ACTA2) was obtained. Alpha smooth muscle actin protein expression (α-SMA) was also measured via immunocytochemistry. RESULTS: Stress-analogous cortisol exposure (cortisol-treated cells) significantly upregulated gene expression of GILZ and pro-fibrotic marker (ACTA2) and downregulated expression of IL1-β when compared to untreated controls (P < 0.05). LPS-treated cells significantly upregulated expression of inflammatory cytokines compared to untreated control cells (IL1-β, P = 0.003; TNF-α, P < 0.001; TGF-β1, p = 0.031). Cortisol + LPS-treated cells upregulated expression of IL1-β, when compared to LPS-treated cells (P = 0.028). Immunocytochemistry revealed positive expression of α-SMA in the cortisol + LPS-treated cells only. CONCLUSION: Stress-analogous cortisol exposure inhibits inflammatory cytokines, upregulates glucocorticoid signaling, and pro-fibrotic gene targets in hVFF. The combination of stress-analogous cortisol exposure and LPS upregulated inflammatory cytokines, glucocorticoid signaling gene expression, and protein expression of α-SMA.