Abstract
Abstract: :
Purpose:. The branched chain fatty acid, 12–methyltetradecanoic acid (12–MTA) identified in sea cucumbers displayed inhibition of both endothelial cell proliferation in vitro and angiogenesis in a chicken chorioallantoic membrane assay. The specific aim of this study was to ascertain the ability of 12–MTA to inhibit corneal angiogenesis induced by P. aeruginosa infection. Methods: Corneal surfaces of BALB/c mice were incised with a needle and P. aeruginosa (2 million cfu) was added onto the wounded cornea of one eye. The contralateral eye (control) was scratched but not infected. 12–MTA (100µmoles) was prepared as an emulsion for topical application. Treatment groups consisted of: Group 1, no treatment; Group 2, vehicle treatment to the cornea of both the challenged and scratch control eye; and Group 3, 12–MTA treatment to both the challenged and scratch control eyes. The treatment commenced 4 days after challenge and then every second day until cessation of experiment 14 days post–challenge. Results: At 7days post–challenge 18/19 mice (95%) in the no treatment Group 1 and 13/20 (65%) in the vehicle treatment Group 2 showed vascularization of the infected eye. However, only 11/23 (48%) of mice receiving12–MTA treatment in Group 3 showed vascularization, this was significantly different from Group 1 (p<0.05). At 14 days post–challenge 18/19 mice (95%) in Group 1 and 15/20 (75%) in Group 2 showed vascularization of the infected eye. While 17/23 (72%) of mice in Group 3 showed vascularization, this finding was significantly different from Group 1 at the 10% level. Of note was that at 7 days the radial extent of vascularization in Group 3 infected cornea was significantly lower than in Group 1 (p=0.001) and there were no significant differences between Groups 1 and 2. No adverse effects on the cornea were observed with 12–MTA in the scratch control eyes in all groups. Cytokine ELISA analyses of corneal extracts at day 14 showed that 12–MTA treatment inhibited keratinocyte chemokine, a pro–angiogenic factor, significantly in comparison to Group 1 (p<0.05). Conclusions: The infrequent dosing, used to minimise stress to the mice, may mask a more significant effect of 12–MTA on corneal neoangiogenesis and progression of the keratitis. Treatment of humans during microbial keratitis typically involves instillation of therapeutics hourly. The results obtained here are promising and suggest that a more marked reduction of inflammation and vessel growth may be found using a daily or twice daily treatment regimen and an increased dosage.
Keywords: neovascularization • cornea: stroma and keratocytes • Pseudomonas