Delayed regression of laser-induced choroidal neovascularization in TNFα-null mice.

We investigated the effects of lacking TNFα on the development and regression of Argon-laser-induced choroidal neovascularization (CNV) in mice. We lasered ocular fundus for induction of CNV in both wild-type (WT) and TNFα-null (KO) mice. Fluorescence angiography was performed to examine the size of CNV lesions. Gene expression pattern of wound healing-related components was examined. The effects of exogenous TNFα on apoptosis of human retinal microvascular endothelial cells (HRMECs) and on the tube-like structure of the cells were investigated in vitro. The results showed that Argon-laser irradiation-induced CNV was significantly larger in KO mice than WT mice on Day 21, but not at other timepoints. Lacking TNFα increased neutrophil population in the lesion. The distribution of cleaved caspase3-labelled apoptotic cells was more frequently observed in the laser-irradiated tissue in a WT mouse as compared with a KO mouse. Exogenous TNFα induced apoptosis of HRMECs and accelerated regression of tube-like structure of HRMECs in cell culture. Taken together, TNFα gene knockout delays the regression of laser-induced CNV in mice. The mechanism underlying the phenotype might include the augmentation of neutrophil population in the treated tissue and attenuation of vascular endothelial cell apoptosis.