Antiuveitis and inhibition of fibroblast-like corneal and conjunctival cell cultures by interleukin-1 blockers, CK 125, CK 126 and CK 128

Review: effects of nitric oxide on eye diseases and their treatment

Both underproduction and overproduction of nitric oxide (NO) could lead to various eye diseases. It is known that endothelial NO synthase (eNOS) and neuronal NOS (nNOS) are activated in normal tissues to produce NO for physiological functions. Thus, underproduction of NO results in various eye diseases which could be corrected by providing NOS substrates or NO donors to lower the intraocular pressure, increase ocular blood flow, relax ciliary muscle, etc. On the other hand, immunological NOS (iNOS) is inducible only in pathological conditions by endotoxins, inflammation, and certain cytokines, such as interleukin-1 (IL-1), IL-6, TNF (tumor necrosis factor) and the like. Once induced, iNOS will produce large amounts of NO for long periods of time, so that NO is converted into NO2, nitrite, peroxynitrite and free radicals to induce pathophysiological actions, such as optic nerve degeneration and posterior retinal degeneration lesion, which lead to glaucoma, retinopathy, age-related macular degeneration (AMD), myopia, cataracts and uveitis. To treat/prevent these eye diseases, inhibitors of iNOS activity and/or iNOS induction could be tried.

Inhibition of interleukin-1-induced uveitis and corneal fibroblast proliferation by interleukin-1 blockers

Interleukin-1 (IL-1) is known to trigger induction of inducible nitric oxide synthase (iNOS) to persistently mass produce nitric oxide (NO) to induce various diseases such as cancer, inflammation, Alzheimer's disease and eye diseases, including uveitis, retinopathy, age-related macular degeneration, glaucoma and myopia. Therefore, IL-1 blockers could become an important class of drugs to fight numerous diseases. Among the many compounds studied so far, 1-methyl hydrazino analogs are among the most promising agents to be developed. A minor structural change of 1-methyl hydrazino group into 1-methyl thiosemicarbazido group enhanced their anti-inflammatory activity but reduced their antiproliferation activity on corneal fibroblast cell growth.

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.