TGF-β/RhoA/ROCK Signaling Activation Orchestrates Ciliary Body EMT and Fibrosis in Myopia

Background: Dysregulation of the transforming growth factor (TGF)-β/Ras homolog family member A (RhoA)/Rho-associated protein kinase (ROCK) pathway can lead to fibrotic changes in ocular diseases. The present study investigated its role in epithelial–mesenchymal transition (EMT) and fibrosis in the ciliary body in lens-induced myopia (LIM) guinea pigs. Methods: A lens-induced myopia model was established in guinea pigs. Refraction, axial length, and ciliary body alterations were assessed via quantitative polymerase chain reaction (qPCR), western blot, PCR array, histological, and biomechanical analyses. Upstream mechanisms were explored using Ingenuity Pathway Analysis. Functional experiments were performed using the ROCK inhibitor Y-27632. Results: Refraction and axial length were increased in the myopic ciliary body in a time-dependent manner. Protein levels of TGF-β1, RhoA, ROCK1, ROCK2, α-smooth muscle actin (α-SMA), and matrix metalloproteinase (MMP)1 were significantly elevated in the myopic ciliary body, peaking at 6 weeks. In the ultra-early stage of lens myopia, functional changes such as refractive errors and increased biological parameters like axial length occur earlier than changes in EMT transcription factor levels. The differentially expressed genes were involved in cell movement, development, growth, proliferation, and transport in early myopia. Compared with those of normal animals, the Ca2+ inflow and Young’s modulus of the ciliary body were greater, the ciliary body elasticity was lower, and the degree of tissue fibrosis was aggravated in animals with deepening myopia. Furthermore, ROCK inhibition can alleviate the pathological levels of EMT and fibrosis in the cilia of myopic guinea pigs. Conclusion: Collectively, our findings indicate that activation of the TGF-β/RhoA/ROCK pathway induces EMT in the ciliary body, promotes Ca2+ inflow, and reduces ciliary body elasticity in myopic animals, resulting in tissue fibrosis and dysfunction. It provides a new perspective on the pathological mechanisms of ciliary body fibrosis in the development of myopia.