Effect of interleukin-1 blockers, CK112, and CK116 on rat experimental choroidal neovascularization in vivo and endothelial cell cultures in vitro

PURPOSE

The aim of this study was to investigate the effect of interleukin-1 blockers, CK112 and CK116, on laser-induced experimental choroidal neovascularization (CNV) in rat models in vivo and endothelial cell proliferation in vitro.

METHODS

Male Brown Norway rats were anesthetized to receive Nd:YAG laser to break the Bruch's membrane. CK112, CK116, and prednisolone were given once-daily through intraperitoneal (i.p.) injection after laser treatment for 4 weeks. The development of CNV was determined by fluorescein angiography performed on weeks 2 and 4. Human umbilical vein endothelial cells (HUVEC) were tested with proliferation assay with CK112, CK116, and prednisolone at different concentrations.

RESULTS

The intensity of fluorescein leakage from the photocoagulated lesions decreased significantly, compared to the control group (treated with dimethyl sulfoxide [DMSO] only), following CK112, CK116, and prednisolone treatment. Four (4) weeks after administration, CK112, at 10 mg/kg and 30 mg/kg, inhibited CNV development to 75% and 77% of the control group, respectively (P < 0.01). Both CK116, 10 mg/kg, and prednisolone, 5 mg/kg, inhibited the CNV development to 85% of the control group (P < 0.05). All three compounds interfered with the endothelial cell proliferation significantly. The reduction of the endothelial cells was 50.5% (P < 0.01), 28.5% (P < 0.05), and 23.1% (P < 0.05), respectively, in 500 microg/mL, 300 microg/mL, and 100 microg/mL of the CK112-treated group. CK116 inhibited the cell proliferation significantly to 77.2% of the control group at 500 microg/mL (P < 0.05).

CONCLUSIONS

CK112 and CK116 inhibited the development of CNV in the rat model and interfered with vascular endothelial cell proliferation in vitro. Our results suggest that CK112 and CK116 may be good candidates to inhibit ocular neovascularization related to age-related macular degeneration (ARMD).

Suppression of interleukin-1alpha-induced uveitis and inhibition of fibroblast-like cell proliferation by synthetic interleukin-1 blockers

To treat uveitis and prolong the functional life of filtration surgery on glaucomatous eyes, some interleukin-1 (IL-1) blockers were used to inhibit IL-1-induced uveitis in rat eyes and to suppress proliferation of fibroblast-like corneal and conjunctival cells in the cell cultures, respectively. It was found in this research that the blood-aqueous barrier can be broken by IL-1alpha to allow fluorescein to enter the eyeballs and to be detected by fluorotron. The uveitis was effectively blocked by the IL-1 blockers studied in this research. It was also noted that the proliferation of fibroblast-like corneal and conjunctival cells was effectively inhibited by IL-1 blockers. The inhibition of cell growth seems to be caused primarily by the inhibition of RNA synthesis. There was a significant difference in the potency of IL-1 blockers to inhibit corneal vs. conjunctival cells. It was noted that conjunctival cells were more easily inhibited by IL-1 blockers than corneal cells. These results indicate that IL-1 blockers can suppress the proliferation of conjunctival cells at dose levels which do not affect the normal cell growth of corneal cells.

Antagonism of interleukin-1 (IL-1)-induced uveitis with synthetic IL-1 blockers

Because of the discovery of potent interleukin-1 (IL-1) blocking effects by CK-103A (4,6-dihydropyridazino[4,5-c]pyridazin-5 (1H)-ones) on rat uveitis induced by IL-1, numerous derivatives of CK-103A have been synthesized and their efficacies on the same animal model studied. The uveitis was induced by injection of 1 ng IL-1/10 microliters intravitreally. The inflammation reached peak at 12 hr after the injection of IL-1. The prevention/blockade of IL-1-induced uveitis was measured at this peak inflammation time point. It was found that 8 out of 12 CK-analogs studied produced an effective blockade of IL-1-induced uveitis. Most of them were at least equipotent or even more potent than prednisolone in blocking IL-1-induced uveitis. It is concluded that most dihydropyridazinopyridazin derivatives are effective anti-uveitis compounds. Some could be found to be safe and useful for the treatment of this dreadful disease.