Purpose: To investigate the combination therapeutic effects of topical doxycycline temperature-sensitive hydrogel (DTSH) and bevacizumab on corneal neovascularization (CNV) and corneal wound healing (CWH) and to explore the underlying mechanisms of doxycycline on CNV and CWH.
Methods: Rats were treated with a saline solution, topical DTSH (0.1%), topical bevacizumab (2.5 mg/0.1 mL), or a DTSH and bevacizumab combination. For the bFGF-induced CNV model (n = 15/group), the length and area of CNV were measured on day 7. In the alkali burn model (n = 33/group), the length and area of CNV were determined on days 3, 7, 14, and 21 after alkali burn. The activity of matrix metalloproteinase (MMP)-2 and MMP-9 was determined by a fluorogenic peptide substrate. Western blot, real-time PCR, and ELISA were used to analyze the expression of induced nitric oxide synthase (iNOS), VEGF, VEGFRS, MMP-2, MMP-9, and IL-1β.
Results: Combination therapy more effectively inhibited CNV than therapy with topical bevacizumab or DTSH alone. DTSH combined with bevacizumab significantly accelerated delayed CWH caused by topical bevacizumab in the alkali burn model (P = 0.018). Combination therapy showed better inhibitory effects on MMP expression and phosphorylated VEGFR1 and VEGFR2. With DTSH treatment, doxycycline inhibited the activity and expression of MMPs, the expression of VEGF and of phosphorylated VEGFR1 and VEGFR2, and the production of iNOS and IL-1β in local cornea.
Conclusions: Doxycycline enhances the inhibitory effects of bevacizumab on CNV and prevents its side effects on CWH, possibly by inhibiting the expression and activity of MMPs, the expression of VEGF and of phosphorylated VEGFR1 and VEGFR2, and the production of iNOS and IL-1β.