The Novel Rho Kinase (ROCK) Inhibitor K-115: A New Candidate Drug for Neuroprotective Treatment in Glaucoma

PURPOSE.To assess the therapeutic potential of edaravone, a free radical scavenger that is used for the treatment of acute brain infarction and amyotrophic lateral sclerosis, in a mouse model of optic nerve injury (ONI).METHODS. Two microliters of edaravone (7.2 mM) or vehicle were injected intraocularly 3 minutes after ONI. Optical coherence tomography, retrograde labeling of retinal ganglion cells (RGCs), histopathology, and immunohistochemical analyses of phosphorylated apoptosis signal-regulating kinase-1 (ASK1) and p38 mitogen-activated protein kinase (MAPK) in the retina were performed after ONI. Reactive oxygen species (ROS) levels were assessed with a CellROX Green Reagent.RESULTS. Edaravone ameliorated ONI-induced ROS production, RGC death, and inner retinal degeneration. Also, activation of the ASK1-p38 MAPK pathway that induces RGC death following ONI was suppressed with edaravone treatment. CONCLUSIONS.The results of this study suggest that intraocular administration of edaravone may be a useful treatment for posttraumatic complications.Keywords: edaravone, oxidative stress, neuroprotection, ASK1, retinal ganglion cell T raumatic optic neuropathy is a common clinical problem that occurs in 0.5% to 5% of patients with closed head injury.1 Damage to the optic nerve induces secondary swelling within the optic canal, accompanied by subsequent retinal ganglion cell (RGC) loss and optic nerve atrophy.2 Although no large natural history or randomized controlled trials have been published, corticosteroid therapy and optic canal decompression surgery are not considered to be effective for patients with traumatic optic neuropathy.3 Research into finding therapeutic targets for treatment of traumatic optic neuropathy indicated that neuroprotection might be an effective strategy and studies using an optic nerve injury (ONI) model in rodents have provided useful information. For example, neurotrophins, such as brain-derived neurotrophic factor and ciliary neurotrophic factor, protect retinal RGCs in an ONI model. [4][5][6] Also, inhibitors of glutamate receptors, tumor necrosis factor receptors, and nitric oxide synthase may be effective for RGC protection. 7-11The ONI model mimics some aspects of glaucoma, including RGC death induced by oxidative stress, and therefore, it is also a useful animal model for glaucoma.Edaravone is a free radical scavenger that has been used clinically to treat acute brain infarction and amyotrophic lateral sclerosis (ALS). Edaravone quenches hydroxyl radicals ( Á OH) and inhibits lipid peroxidation dependent and independent of Á OH. 12,13 In an in vitro cell culture study using the RGC-5 to study the neurobiology of RGCs, edaravone scavenged the intracellular Á OH, superoxide anion (O 2 ÀÁ ), and hydrogen peroxide (H 2 O 2 ) while demonstrating the strongest scavenging activity against14 Recent studies have shown that oxidative stress plays an important role in many ocular diseases including glaucoma. [15][16][17][18] Interestingly, edaravone attenuates retinal ischemia/reperfusion ...

“…28 Mice were killed by cervical dislocation at 6 hours after ONI and eyes were enucleated. Retinas were isolated for a whole-mount preparation in cold PBS.…”

Section: Detection Of Oxidative Stress Using Cellrox Green Reagentmentioning

confidence: 99%

“…28,31 To examine the effect of edaravone on ONI-induced ROS production, we performed staining of ROS using CellROX green reagent 31 in the wholemount retina. Because ROS is a powerful activator of ASK1-p38 MAPK signaling, we also performed CellROX green reagent analyses at 6 hours after ONI.…”

Section: Edaravone Suppresses Ros Production Following Onimentioning

confidence: 99%

Edaravone Prevents Retinal Degeneration in Adult Mice Following Optic Nerve Injury

Akiyama

Azuchi

Guo

et al. 2017

“…[19][20][21][22] In addition, it has been reported that ripasudil exhibits neuroprotective effects for retinal ganglion cells following systemic administration in the rat optic nerve crush model. 23 A previous study with the radiolabeled drug showed that ripasudil reached the retina and choroid after eye drop administration in rabbits. 15,24 However, it is not known if ripasudil treatment inhibits ocular inflammation in the anterior chamber or retina, and the role of the Rho/ROCK pathway in ocular inflammation and leukocyte adhesion in EIU has not yet been clarified.…”

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confidence: 99%

The Anti-Inflammatory Effect of Ripasudil (K-115), a Rho Kinase (ROCK) Inhibitor, on Endotoxin-Induced Uveitis in Rats

Uchida

Honjo

Yamagishi

et al. 2017

Citation: Uchida T, Honjo M, Yamagishi R, Aihara M. The anti-inflammatory effect of ripasudil (K-115), a Rho kinase (ROCK) inhibitor, on endotoxin-induced uveitis in rats. Invest Ophthalmol Vis Sci. 2017;58:5584-5593. DOI:10.1167/iovs.17-22679 PURPOSE. To investigate the anti-inflammatory properties of ripasudil, a Rho kinase (ROCK) inhibitor, using endotoxin-induced uveitis (EIU) in rats.METHODS. Endotoxin-induced uveitis was induced by footpad injection of lipopolysaccharide (LPS). Ripasudil was administered intraperitoneally 1 hour before and after LPS injection. The aqueous humor was collected 24 hours after injection, and the infiltrating cells, protein concentration, and levels of monocyte chemotactic protein-1 (MCP-1) were determined. Infiltrating cells in the iris ciliary body (ICB) and adherent leukocytes in retinal vessels were evaluated. The mRNA levels of IL-1b, IL-6, TNF-a, and MCP-1 in the retina and ICB were determined. A mouse macrophage cell line, RAW264.7, was stimulated with LPS in the presence or absence of ripasudil, and the expression of MCP-1 and nuclear translocation of nuclear factor (NF)-jB was analyzed.RESULTS. Ripasudil significantly reduced infiltrating cells and protein exudation in the aqueous humor, as well as the number of infiltrating cells in the ICB and adherent leukocytes in retinal vessels in EIU. Additionally, the protein level of MCP-1 in the aqueous humor and mRNA levels of IL-1b, IL-6, TNF-a, MCP-1, and intercellular adhesion molecule-1 in the ICB and retina were suppressed by ripasudil. The production of MCP-1 and nuclear translocation of NF-jB in RAW264.7 cells were also suppressed by ripasudil.CONCLUSIONS. The Rho/ROCK pathway plays a role in adhesion molecule expression and inflammatory cell infiltration in EIU, and ripasudil is a potent anti-inflammatory agent against ocular inflammatory diseases, including acute uveitis and possibly uveitic glaucoma.

“…33 Ripasudil is the first ophthalmic solution approved for the treatment of glaucoma and ocular hypertension in Japan; in 2014, it became available in an eye drop form to increase the outflow of the aqueous humor. [34][35][36] In addition, oral ripasudil protects RGCs after optic nerve injury by suppressing oxidative stress via Nox1 downregulation, 37 but there are few reports about its neuroprotective effects. In the present study, we found that topical ripasudil prevents glaucomatous retinal degeneration in EAAC1 KO mice by stimulating an IOP-independent pathway, in addition to IOPdependent pathways.…”

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confidence: 99%

Topical Ripasudil Suppresses Retinal Ganglion Cell Death in a Mouse Model of Normal Tension Glaucoma

Akaiwa

Namekata

Azuchi

et al. 2018

METHODS. Topical administration (5 lL/day) of two different concentrations of ripasudil (0.4% and 2%) were applied to EAAC1 KO mice from 5 to 12 weeks old. Optical coherence tomography, multifocal electroretinograms, the measurement of intraocular pressure (IOP), and histopathology analyses were performed at 5, 8, and 12 weeks old. Retrograde labeling of retinal ganglion cells (RGCs), immunoblot, and immunohistochemical analyses of phosphorylated p38 mitogen-activated protein kinase (MAPK) in the retina were performed at 8 weeks old.RESULTS. Topical ripasudil ameliorated retinal degeneration and improved visual function in EAAC1 KO mice at both 8 and 12 weeks old. Ripasudil reduced IOP and strongly suppressed the phosphorylation of p38 MAPK that stimulates RGC death in EAAC1 KO mice.CONCLUSIONS. These results suggest that, in addition to IOP reduction, ripasudil prevents glaucomatous retinal degeneration by neuroprotection, which is achieved by suppressing celldeath signaling pathways.