Chemokine Signaling Pathways in Corneal Fibroblasts

TGFbeta mediated transition of corneal fibroblasts from a proinflammatory state to a profibrotic state through modulation of histone acetylation

Corneal fibroblasts exhibit different phenotypes in different phases of corneal wound healing. In the inflammatory phase, the cells assume a proinflammatory phenotype and produce large amounts of cytokines and chemokines, but in the proliferative and remodeling phases, they adapt a profibrotic state, differentiate into myofibroblasts and increase extracellular matrix protein synthesis, secretion, and deposition. In the present study, the molecular mechanisms regulating the transition of corneal fibroblasts from the proinflammatory state to the profibrotic state were investigated. Corneal fibroblasts were treated with TGFbeta, a known profibrotic and anti-inflammatory factor in wound healing, in the absence or presence of trichostatin A (TSA), a histone deacetylase (HDAC) inhibitor. The results revealed that TGFbeta induced the profibrotic transition of corneal fibroblasts, including increased extracellular matrix synthesis, morphological changes, and assembly of actin filaments. Meanwhile, proinflammatory gene expressions of corneal fibroblasts were down-regulated with the treatment of TGFbeta, as confirmed by cDNA microarray, real time PCR and ELISA. Moreover, TSA reversed the TGFbeta-mediated transition of corneal fibroblasts from the proinflammatory state to the profibrotic state, as accompanied by histone hyperacetylations. In conclusion, TGFbeta suppressed the production of proinflammatory factors and enhanced the expression of matrix remodeling genes of corneal fibroblasts in the transition from the proinflammatory state to the profibrotic state, and the dual roles of TGFbeta on the phenotype regulations of corneal fibroblasts were mediated by altered histone acetylation.