Cannabidiol may help prevent scarring on the eye’s surface, according to a new lab study published in Scientific Reports by researchers at the Medical University of Vienna.
The team used cultured human conjunctival epithelial cells, which line the white of the eye and are involved in scarring conditions such as pterygium, severe allergic conjunctivitis, dry eye disease and post-surgical fibrosis. To mimic a fibrotic environment, the researchers treated the cells with transforming growth factor-beta 1 (TGF-β1), a key driver of epithelial-mesenchymal transition (EMT) and tissue scarring.
TGF-β1 pushed the cells into an EMT-like state: they became elongated and more mobile, lost epithelial markers such as E-cadherin and ZO-1, and increased mesenchymal markers including fibronectin, alpha-smooth muscle actin and the EMT-associated transcription factor Snail. Those changes are consistent with a shift toward a pro-fibrotic phenotype.
When CBD was added at non-toxic concentrations (5–10 µM) alongside TGF-β1, it largely prevented those EMT-related changes. The cells retained a more normal, polygonal shape, migration in wound-healing assays slowed, epithelial markers were preserved and mesenchymal markers and Snail expression were reduced toward baseline levels.
Mechanistic experiments pointed to the canonical TGF-β/Smad pathway. CBD cut phosphorylation and nuclear translocation of Smad-2/3, producing an effect similar to the selective TGF-β/Smad inhibitor SB431542. The EMT phenotype was also linked with higher secretion of the inflammatory cytokine interleukin-6, which CBD reduced in a dose-dependent fashion.
The authors caution that the work was done in vitro in a single cell type and does not capture the full, multicellular complexity of conjunctival fibrosis. They note that challenges remain for delivering CBD effectively to ocular tissues. Even so, the findings suggest CBD-based approaches could be explored further as a safer, targeted strategy to limit EMT-driven conjunctival scarring and related inflammatory signaling.
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