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.