Effect of TGFβ and PDGF-B blockade on corneal myofibroblast development in mice

The purpose of this study was to investigate the role of transforming growth factor beta (TGFβ) and/or platelet-derived growth factor-B (PDGF-B) blockade on the differentiation of vimentin and alpha-smooth muscle actin (αSMA)-expressing myofibroblasts associated with haze in mice. Mouse corneas had haze-generating irregular PTK (phototherapeutic keratectomy) and topical treatment with the vectors. Six study groups of PTK treated corneas, with four corneas per group in each experiment, were Group 1) treated with TGFβ-KDEL vector interfering with TGFβ signaling through anomalous sorting of cytokine bound to the expressed altered receptor; Group 2) treated with PDGF-B-KDEL vector interfering with PDGF signaling through anomalous sorting of cytokine bound to the expressed altered receptor; Group 3) treated with both TGFβ-KDEL vector and PDGF-B-KDEL vector to interfere with signaling of both cytokines; Group 4) empty pGFPC1 vector; Group 5) empty pCMV vector; and Group 6) no vector treatment control. At one month after surgery, the corneas were analyzed by immunocytochemistry (IHC) for central stromal cells expressing myofibroblast markers vimentin and αSMA. The stroma of corneas treated with the TGFβ-KDEL vector alone (p < 0.05) or both the TGFβ-KDEL and PDGF-B-KDEL vectors (P < 0.05) had significantly lower density of vimentin-positive cells compared to the corresponding control group. The central stroma of corneas treated with the TGFβ-KDEL vector (p < 0.05) or the PDGF-B-KDEL vector (p < 0.05) had lower density of αSMA-positive cells compared to the corresponding control group. The density of αSMA-positive stromal cells was also significantly lower (p < 0.05) when both the TGFβ-KDEL and PDGF-B-KDEL and vectors were applied together compared to the corresponding control groups. This study provides in situ evidence that TGFβ and PDGF-B have important roles in modulating myofibroblast generation in the mouse cornea after haze-associated injury.

► TGFβ and PDGF-B modulate the development of corneal myofibroblasts in vivo. ► TGFβ increases vimentin+α-smooth muscle actin− (V+A−) myofibroblast precursors. ► PDGF-B modulates the transition of V+A− precursors to V+A+ myofibroblasts.