Purpose: To determine changes in expression of transforming growth factor β-2 (TGF-β2) and basic fibroblast growth factor (bFGF) in scleral desmocytes from anterior and posterior portions of experimentally-induced myopic eyes of guinea pigs.
Methods: Three groups (n = 10) of 2-week-old guinea pigs were used to develop concave lens-induced myopia (LIM) in one eye via the out-of-focus method for 6, 15, or 30 days respectively, while the other eye in each guinea pig served as the self-control (SC). After myopia induction, lenses were removed, and scleral fibroblasts were cultured and passaged twice. TGF-β2 and bFGF expression levels of scleral desmocytes in LIM and SC groups were compared by immunocytochemistry, quantitative real-time PCR (qRT-PCR) and Western blot analyses.
Results: The TGF-β2 expression of the anterior portion of the sclera in the LIM group was significantly higher at 15 days, and at its highest at 30 days after myopia induction compared with the SC group (P < 0.05). The TGF-β2 staining of the posterior sclera in the LIM group began to rise significantly at 6 days, peaked at 15 days and remained significantly higher than that of the anterior part, as well as the SC group, even at 30 days after myopia induction (P < 0.05). BFGF levels in scleral desmocytes from the anterior and posterior regions in the LIM group were both significantly lower than those of the SC group at all time points after myopia induction (P < 0.05). Furthermore, as the myopia progressed, bFGF expression in the anterior and posterior sclera in the LIM group gradually and statistically significantly decreased compared with the SC group (P < 0.05); however, no significant differences were observed between the anterior and posterior parts in the LIM group at any time after myopia induction (P > 0.05). All these results were consistent at the mRNA and protein levels.
Conclusions: During myopia development in lens-induced guinea pigs, the increase in TGF-β2 activity of scleral desmocytes initiated at the posterior pole. Along with the induction time, the TGF-β2 activity in all scleral desmocytes became elevated. By contrast, the bFGF activity showed a general decline in all scleral desmocytes, rather than mainly in the posterior pole. These results imply that expression of TGF-β2 in scleral desmocytes plays a direct role, while that of bFGF exerts an indirect role in myopia development.