Carnitine acetyltransferase (CrAT) involvement in TGF-β1-induced keratocyte transdifferentiation and corneal fibrosis in vitro.

The cornea is the transparent anterior tissue of the eye, and its integrity is essential for normal vision. Following injury, activation of the TGF-β pathway drives the transdifferentiation of corneal stromal cells, known as keratocytes (KTCs), into myofibroblasts, which are responsible for corneal fibrosis. This phenotypic transition may be associated with metabolic reprogramming, in which carnitine acetyltransferase (CrAT), a mitochondrial enzyme involved in acetyl-CoA/CoA homeostasis and energy metabolism, could play a key role. However, the contribution of CrAT to KTC transdifferentiation and corneal fibrosis remains unclear. Therefore, this study aimed to establish an in vitro model of corneal fibrosis to investigate the role of CrAT during KTCs-to-myofibroblast transition and evaluate its potential as a therapeutic target. To this end, primary KTCs were isolated from human corneal stromal lenticules obtained during refractive surgery and then stimulated with TGF-β1 (5 ng/mL), with or without L-Carnitine (5mM), for up to 14 days. KTCs phenotype and CrAT expression were assessed by qPCR, Western blotting and immunofluorescence, while CrAT activity was measured by enzymatic assay. Results showed that TGF-β1 induced KTC-to-myofibroblast transition, characterized by increased gene and protein expression of fibronectin, collagen I and α-SMA, consistent with the development of a fibrotic phenotype. Preliminary data further indicate that both CrAT expression and enzymatic activity were reduced in TGF-β1-treated KTCs. In conclusion, these initial findings support the establishment of a reliable in vitro model of corneal fibrosis and suggest a link between KTCs transdifferentiation and CrAT activity, supporting further investigation of its mechanistic and therapeutic relevance.