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N. Kopsachilis, F. Kruse, U. Welge - Luessen; A Novel Mechanism of ultraviolet A and Riboflavin Mediated Corneal Crosslinking via Induction of Tissue Transglutaminases. Invest. Ophthalmol. Vis. Sci. 2009;50(13):5472.
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© ARVO (1962-2015); The Authors (2016-present)
Collagen crosslinking using ultraviolet- A (UVA) -irradiation combined with the photosensitizer riboflavin is a new technique for treating progressive keratokonus. The mechanism Purpose of this study is to examine whether immortalized human keratocytes (HCKi) are capable of expressing and secreting tissue transglutaminase (tTgase), an enzyme cross-linking extracellular matrix (ECM) proteins, and whether tTgase and synthesis of cross-linked fibronectin are increased after treatment of HCKi cells with ultraviolet- A (UVA) -irradiation combined with riboflavin, thus providing another possible physiological mechanism of the cross-linking pathway.
Cell cultures established from immortalised human keratocytes were treated with 0.025% riboflavin solution and UVA (370 nm)-irradiance 0.5 mW/cm2 for 30 min. Induction of tTgase and fibronectin was investigated by immunohistochemistry, Real-Time PCR and Western blot analysis. Extracellular tTgase activity was measured by the incorporation of biotinylated cadeverine into fibronectin.
Treatment of cultured HCKi cells with combined UVA irradiation and riboflavin increased the tTgase mRNA and protein levels. This effect was not observed in cells treated either with Riboflavin or UVA-radiation alone. Incorporation of biotinylated cadaverine was markedly increased when HTM cells were treated with combined UVA irradiation and riboflavin.
The enzymes tTgase and fibronectin are expressed and inducible by ultraviolet- A (UVA) -irradiation combined with riboflavin in cultured HCKi cells. This mechanism provides more information about the physiology of corneal crosslinking and may be a useful approach to achieve stiffness in artificial cornea models.
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