The Soluble Guanylate Cyclase Stimulator IWP-953 Increases Conventional Outflow Facility in Mouse Eyes

Abstract

PurposeThe nitric oxide (NO)–cyclic guanosine-3′,5′-monophosphate (cGMP) pathway regulates aqueous humor outflow and therefore, intraocular pressure. We investigated the pharmacologic effects of the soluble guanylate cyclase (sGC) stimulator IWP-953 on primary human trabecular meshwork (HTM) cells and conventional outflow facility in mouse eyes.MethodsCyclic GMP levels were determined in vitro in HEK-293 cells and four HTM cell strains (HTM120/HTM123: predominantly myofibroblast-like phenotype, HTM130/HTM141: predominantly endothelial-like phenotype), and in HTM cell culture supernatants. Conventional outflow facility was measured following intracameral injection of IWP-953 or DETA-NO using a computerized pressure-controlled perfusion system in enucleated mouse eyes ex vivo.ResultsIWP-953 markedly stimulated cGMP production in HEK-293 cells in the presence and absence of DETA-NO (half maximal effective concentrations: 17 nM, 9.5 μM). Similarly, IWP-953 stimulated cGMP production in myofibroblast-like HTM120 and HTM123 cells, an effect that was greatly amplified by the presence of DETA-NO. In contrast, IWP-953 stimulation of cGMP production in endothelial-like HTM130 and HTM141 cells was observed, but was markedly less prominent than in HTM120 and HTM123 cells. Notably, cGMP was found in all HTM culture supernatants, following IWP-953/DETA-NO stimulation. In paired enucleated mouse eyes, IWP-953 at 10, 30, 60, and 100 μM concentration-dependently increased outflow facility. This effect (89.5%) was maximal at 100 μM (P = 0.002) and in magnitude comparable to DETA-NO at 100 μM (97.5% increase, P = 0.030).ConclusionsThese data indicate that IWP-953, via modulation of the sGC–cGMP pathway, increases aqueous outflow facility in mouse eyes, suggesting therapeutic potential for sGC stimulators as novel ocular hypotensive drugs.

Soluble Guanylate Cyclase Stimulators and Activators

“…Additionally, human candidate gene studies revealed that a variant in the locus encoding genes for GC1 are associated with one form of primary open angle glaucoma (Buys et al 2013). Furthermore, several studies have demonstrated that NO, cGMP, and sGC modulators may reduce intraocular pressure through regulation of aqueous humor outflow from the anterior chamber through the trabecular meshwork and Schlemm's canal (Kotikoski et al 2003;Ge et al 2016). Emerging data suggest that modulators of cGMP availability may also prevent optic nerve damage, independent of effects on ocular pressure.…”

The many faces of the trabecular meshwork cell

“…Upon reaching confluence in culture, JCT cells appear to have a smooth muscle-like or fibroblastic appearing morphology (Figure 1). Whether TM and JCT cells are the same cell “type” in different biological environments or two different cell types has been the subject of debate for decades (Flugel et al, 1991, Coroneo et al, 1991) (Ge et al, 2016). Regardless of their phenotype, TM cells are contact inhibited with primary isolates and low passage cells having a doubling time in culture of less than two days (Polansky et al, 1979).…”

“…Most investigators use high amounts of serum (10–20%) to promote cell division while expanding cultures. Some, use a differentiation step once cells are confluent whereby supplementary growth factors are withdrawn (such as FGF) and/or fetal bovine serum levels are reduced (to 1–10%) (Wax et al, 1989, Ge et al, 2016). Freddo and colleagues have reported in vivo leakage of serum proteins at the iris root adjacent to TM tissue, so it is likely that the TM in vivo is also exposed to serum components (Freddo, 1993).…”

Structure/function of the soluble guanylyl cyclase catalytic domain

“…Older mice lacking the αGC-1 polypeptide had typical POAG symptoms including reduced aqueous humor outflow, increased IOP, and damage to the optic nerve [16], directly implicating GC-1 in the disease. More recently, treatment of mouse eyes with elevated IOP and reduced aqueous humor outflow using a novel GC-1 stimulator improved ocular flow rate over the vehicle-treated group; similar results were observed using an NO-donor [17]. Targeting the NO/GC-1/cGMP pathway for improved optic blood flow may prove useful in the treatment of POAG.…”