It has been reported that intravitreous administration of anti-mouse IL18 antibody increases laser-induced choroidal neovascularization (CNV) in mice (Doyle et al. Nat Med 2012). However, since those experiments compared an anti-mouse IL18 antibody to a sham injection group, we tested the putative angiogenic effects of this antibody using biologically and chemically rigorous controls in order to clarify the role IL18 in laser-induced CNV.Methods
Laser photocoagulations were performed to perforate Bruch’s membrane followed by intravitreous injections, and the eyes were collected and analyzed on day 7 after laser treatment. Laser-induced CNV lesions were stained with isolectin B4 and volumes quantified using z-stack on a confocal microscope system (Leica). We tested the Abcam anti-mouse IL18 antibody used by Doyle et al. which was dissolved in 50% glycerol, an MBL anti-mouse IL18 antibody, as well as isotype control antibodies in appropriate control buffers.Results
We found that MBL anti-mouse IL18 antibody neutralized IL18-induced cellular signaling whereas the Abcam antibody did not do so. We also found that the Abcam IL18 antibody increased CNV whereas the MBL antibody did not. We found that glycerol increased CNV to the same extent as the Abcam IL18 antibody, and that the Abcam IL18 antibody in glycerol did not increase CNV in mice deficient in Aquaporin-1, a channel that is permeant to glycerol and promotes angiogenesis.Conclusion
IL18 blockade does not increase CNV. The previously reported results are an artifact of pro-angiogenic glycerol in which the Abcam IL18 antibody is dissolved.