Changes in Cytokine Signaling and Extracellular Matrix Production Induced by Inflammatory Factors in Cultured Vocal Fold Fibroblasts

Abstract

Objectives: Modulating cytokine signaling in vocal fold fibroblasts after injury may influence extracellular matrix (ECM) production and eventual fibrotic outcome. To evaluate previously established in vivo cytokine and ECM gene expression hypotheses, we examined in vitro vocal fold fibroblast responses to exogenous inflammatory factor stimulation.

Methods: Rat vocal fold fibroblast lines derived from expiants were separately treated with interleukin-1β (IL-1β), interferon gamma (IFN-γ), tumor necrosis factor a (TNF-α), transforming growth factor β subtype 1 (TGF-β1), or prostaglandin E2 (PGE2). We examined the in vitro messenger RNA expression profiles of IL-1β, IFN-γ, TNF-α, TGF-β1, and cyclooxygenase 2 (COX-2), as well as those of hyaluronic acid synthase (HAS) 1, HAS-2, procollagen subtype 1, and procollagen subtype 3, at 1, 4, 8, 16, 24, and 72 hours after treatment, and compared them to those of untreated fibroblasts and in vivo data, using real-time reverse transcription-polymerase chain reaction.

Results: IL-Iβ and TNF-α induced each other and synergistically increased HAS-1 and HAS-2 expression. PGE₂ also up-regulated HAS-1 and HAS-2 expression. IFN-γ, IL-1β, TNF-α, and TGF-β1 up-regulated HAS expression alongside either transient up-regulation of, or no change in, procollagen 1 and 3 expression. Most treatments appeared to suppress procollagen expression, possibly through HAS up-regulation. All inflammatory factors attenuated TGF-β1 expression.

Conclusions: These results confirm several in vivo trends, identify potential cytokine pathways and therapeutic candidates, and suggest the utility of this in vitro setup for future studies.