Effects of ripasudil, a ROCK inhibitor, on retinal edema and nonperfusion area in a retinal vein occlusion murine model

RhoA/rho kinase pathway activation in age-associated endothelial cell dysfunction and thrombosis

The small GTPase RhoA and the downstream Rho kinase (ROCK) regulate several cell functions and pathological processes in the vascular system that contribute to the age-dependent risk of cardiovascular disease, including endothelial dysfunction, excessive permeability, inflammation, impaired angiogenesis, abnormal vasoconstriction, decreased nitric oxide production and apoptosis. Frailty is a loss of physiological reserve and adaptive capacity with advanced age and is accompanied by a pro-inflammatory and pro-oxidative state that promotes vascular dysfunction and thrombosis. This review summarises the role of the RhoA/Rho kinase signalling pathway in endothelial dysfunction, the acquisition of the pro-thrombotic state and vascular ageing. We also discuss the possible role of RhoA/Rho kinase signalling as a promising therapeutic target for the prevention and treatment of age-related cardiovascular disease.

ROCK inhibitors in ophthalmology: A critical review of the existing clinical evidence

Rho kinase (ROCK) inhibitors have emerged as a key therapeutic class of interest in ophthalmology over the last decade. Promising in vitro studies laid the foundations for the development of novel therapeutic agents that target the ROCK signalling pathway in ocular disease, with subsequent clinical trials supporting their use. Corneal endothelial disease, glaucoma, and vitreoretinal disease are the major pathologies in which ROCK inhibitors have been investigated to date. Ripasudil and netarsudil represent the current leaders in this pharmaceutical group, having been extensively validated and approved for use in glaucoma in some countries. Less substantial evidence exists for fasudil in ophthalmic use. ROCK inhibitors are also increasingly used in cultured endothelial cell grafting and as an adjunct to aid in endothelial cell migration and replication in Descemet's stripping procedures or Descemet's membrane injuries. This review has synthesised both established and emerging research to provide a practical guide to prescribing in this drug class. Drug efficacies, side effect profiles, and the demographic and clinical characteristics of appropriate drug candidates are discussed.

Risk Factors and Treatment Strategy for Retinal Vascular Occlusive Diseases

Retinal occlusive diseases are common diseases that can lead to visual impairment. Retinal artery occlusion and retinal vein occlusion are included in the clinical entity, but they have quite different pathophysiologies. Retinal artery occlusion is an emergent eye disorder. Retinal artery occlusion is mainly caused by thromboembolism, which frequently occurs in conjunction with life-threatening stroke and cardiovascular diseases. Therefore, prompt examinations and interventions for systemic vascular diseases are often necessary for these patients. Retinal vein occlusion is characterized by retinal hemorrhage and ischemia, which may impair visual function via several complications such as macular edema, macular ischemia, vitreous hemorrhage, and neovascular glaucoma. Even though anti-vascular endothelial growth factor therapy is the current established first-line of treatment for retinal vein occlusion, several clinical studies have been performed to identify better treatment protocols and new therapeutic options. In this review, we summarize the current findings and advances in knowledge regarding retinal occlusive diseases, particularly focusing on recent studies, in order to provide an update for a better understanding of its pathogenesis.

Combined intravitreal injection of bevacizumab and a ROCK inhibitor (fasudil) for refractory macular edema secondary to retinal vein occlusion: a pilot study

Background

To investigate the adjunctive effect of an intravitreal ROCK inhibitor (fasudil) in combination with intravitreal bevacizumab (IVB) on refractory macular edema secondary to retinal vein occlusion (RVO).

Methods

In this prospective interventional case series, 17 eyes of 17 patients (10 men, 7 women) with refractory RVO-related macular edema underwent three consecutive intravitreal injections of bevacizumab plus fasudil. Monthly evaluation was continued up to 12 months and IVB injection was performed if needed during the follow-up. Changes in the best corrected visual acuity (BCVA) was the primary outcome measure. The secondary outcome measures included central macular thickness (CMT) changes and any adverse events.

Results

BCVA significantly improved (mean change: −0.15 LogMAR; P = 0.017) after 3 consecutive intravitreal injections of fasudil in combination with bevacizumab. CMT significantly decreased (mean change: −206 µm; P = 0.028). The anatomical and functional improvement was maintained during the 12 month follow-up. No adverse effects were noticed.

Conclusion

Intravitreal ROCK inhibitors may break the resistance to anti-VEGF therapy and improve the RVO induced macular edema via affecting the VEGF-independent pathways.

Update on Management of Non-proliferative Diabetic Retinopathy without Diabetic Macular Edema; Is There a Paradigm Shift?

Diabetic retinopathy (DR) is the major cause of visual impairment and blindness in the working-age population. Conventional management for nonproliferative diabetic retinopathy (NPDR) without diabetic macular edema (DME) is derived from the findings of the Early Treatment Diabetic Retinopathy Study (ETDRS). Although the ETDRS protocol basically includes observation, selected cases of severe NPDR may undergo scatter laser photocoagulation. Post-hoc analysis of recent trials has shown that patients with NPDR receiving intravitreal anti-vascular endothelial growth factor (anti-VEGF) for DME would experience improvement in the DR severity scale (DRSS). In addition, recent randomized trials (PANORAMA and Protocol W) have revealed that early intervention with intravitreal aflibercept in eyes with moderately severe to severe NPDR is associated with significant improvement in DRSS and reduced vision-threatening complications of DR. Based on recent studies, it seems that the therapeutic approach to NPDR may undergo a substantial change and a paradigm shift toward considering early intervention with the administration of intravitreal anti-VEGF injections. However, the long-term results and the duration of adherence to anti-VEGF therapy for eyes with NPDR are not yet defined. It is also not apparent whether improvement in DRSS is a true disease modification. Studies showed that DRSS improvement is not associated with retinal reperfusion. In addition, DRCR.net Protocol W showed no visual acuity benefit with the early intravitreal aflibercept injection in moderate to severe NPDR as compared with performing observation plus intravitreal aflibercept applied only after progression to proliferative DR or vision-impairing DME. The cost-benefit ratio is also a challenge. Herein, we look at different aspects of early anti-VEGF application and discuss its pros and cons in the process of treating NPDR.

Evaluation of an Intravitreal Rho-Associated Kinase Inhibitor Depot Formulation in a Rat Model of Diabetic Retinopathy

Rho-associated kinase (ROCK) activation was shown to contribute to microvascular closure, retinal hypoxia, and to retinal pigment epithelium (RPE) barrier disruption in a rat model of diabetic retinopathy. Fasudil, a clinically approved ROCK inhibitor, improved retinal perfusion and reduced edema in this model, indicating that ROCK inhibition could be a promising new therapeutic approach for the treatment of diabetic retinopathy. However, due to its short intravitreal half-life, fasudil is not suitable for long-term treatment. In this study, we evaluated a very potent ROCK1/2 inhibitor (BIRKI) in a depot formulation administered as a single intravitreal injection providing a slow release for at least four weeks. Following BIRKI intravitreal injection in old Goto-Kakizaki (GK) type 2 diabetic rats, we observed a significant reduction in ROCK1 activity in the retinal pigment epithelium/choroid complex after 8 days and relocation of ROCK1 to the cytoplasm and nucleus in retinal pigment epithelium cells after 28 days. The chronic ROCK inhibition by the BIRKI depot formulation restored retinal pigment epithelial cell morphology and distribution, favored retinal capillaries dilation, and reduced hypoxia and inner blood barrier leakage observed in the diabetic retina. No functional or morphological negative effects were observed, indicating suitable tolerability of BIRKI after intravitreous injection. In conclusion, our data suggest that sustained ROCK inhibition, provided by BIRKI slow-release formulation, could be a valuable treatment option for diabetic retinopathy, especially with regard to the improvement of retinal vascular infusion and protection of the outer retinal barrier.

Rho GTPases in Retinal Vascular Diseases

The Rho family of small GTPases (Rho GTPases) act as molecular switches that transduce extrinsic stimuli into cytoskeletal rearrangements. In vascular endothelial cells (ECs), Cdc42, Rac1, and RhoA control cell migration and cell–cell junctions downstream of angiogenic and inflammatory cytokines, thereby regulating vascular formation and permeability. While these Rho GTPases are broadly expressed in various types of cells, RhoJ is enriched in angiogenic ECs. Semaphorin 3E (Sema3E) releases RhoJ from the intracellular domain of PlexinD1, by which RhoJ induces actin depolymerization through competition with Cdc42 for their common effector proteins. RhoJ further mediates the Sema3E-induced association of PlexinD1 with vascular endothelial growth factor receptor (VEGFR) 2 and the activation of p38. Upon stimulation with VEGF-A, RhoJ facilitates the formation of a holoreceptor complex comprising VEGFR2, PlexinD1, and neuropilin-1, leading to the prevention of VEGFR2 degradation and the maintenance of intracellular signal transduction. These pleiotropic roles of RhoJ are required for directional EC migration in retinal angiogenesis. This review highlights the latest insights regarding Rho GTPases in the field of vascular biology, as it will be informative to consider their potential as targets for the treatment of aberrant angiogenesis and hyperpermeability in retinal vascular diseases.

High-expression of ROCK1 modulates the apoptosis of lens epithelial cells in age-related cataracts by targeting p53 gene

Background

Age-related cataract (ARC) is a serious visual impairment disease, and its pathogenesis is unclear. This article aims to investigate the role of ROCK1 in the apoptosis of lens epithelial cells (LECs) in age-related cataracts.

Methods

We collect anterior capsule samples from normal people, patients with age-related cataracts, young mice and naturally aging cataract mice. The oxidative stress-induced apoptosis model was constructed by cultivating HLE-B3 cells with H₂O₂. MTT, Hoechst 33342, and TUNEL assay were performed to explore proliferation and apoptosis. HE assay was used to observe cell morphology. The gene and protein expression were assessed by quantitative real-time PCR, western blot, immunofluorescence, and immunohistochemical staining.

Result

The results from the clinic and mice experiments showed that the numbers of lens epithelial cells from cataract individuals were less than the control individuals. In vitro, the apoptotic cells were increased in lens epithelial cells under H₂O₂ treatment. The ROCK1 protein level increased in the lens epithelial cells from age-related cataract patients and the old mice, respectively. Meanwhile, the up-regulation of the ROCK1 gene was associated with H₂O₂-induced HLE-B3 cells apoptosis. MTT and apoptosis assay showed ROCK1 was necessary in mediating H₂O₂-induced lens epithelial cells apoptosis through ROCK1 over-expression and knockdown experiment, respectively. Further investigation showed that p53 protein levels had been increased during ROCK1-mediated apoptosis in response to H₂O₂. Besides, ROCK1 phosphorylated p53 at ser15 to up-regulate its protein level.

Conclusions

This study established the novel association of ROCK1/p53 signaling with lens epithelial cells apoptosis and age-related cataract genesis.

Novel immunotherapeutic effects of topically administered ripasudil (K-115) on corneal allograft survival

Corneal allograft survival is mediated by the variety of immunological reactions and wound healing process. Our aim was to explore the effects of topical administration of ripasudil, a selective Rho-associated coiled-coil protein kinase inhibitor, on corneal allograft survival. Ripasudil was administered to mice thrice a day after allogeneic corneal transplantation. Corneal graft survival, opacity, neovascularization, re-epithelization, immune cell infiltration, and mRNA levels of angiogenic and pro-inflammatory factors in the grafted cornea and draining lymph nodes (dLNs) were evaluated with slit-lamp microscopy, immunohistochemistry, flow cytometry, and polymerase chain reaction. Graft survival was significantly prolonged with lower graft opacity and neovascularization scores in 0.4% and 2.0% ripasudil-treated groups, and mRNA levels of angiogenic and pro-inflammatory factors in ripasudil-treated grafted corneas were reduced. Moreover, 0.4% and 2.0% ripasudil reduced CD45⁺-infiltrated leukocyte frequency, Cd11b and Cd11c mRNA levels, and the frequencies of mature dendritic cells, IFNγ-, and IL-17- producing CD4⁺T cells in the dLNs of recipients. Re-epithelization rate of the grafted cornea was significantly higher in the 0.4% and 2.0% ripasudil groups than in the control. Topically applied ripasudil prolonged graft survival by downregulating neovascularization and inflammation factors, while promoting corneal re-epithelization, suggesting that ripasudil may be useful for suppressing immunological rejection in corneal transplantation.

Endothelial activation of caspase-9 promotes neurovascular injury in retinal vein occlusion

Central nervous system ischemic injury features neuronal dysfunction, inflammation and breakdown of vascular integrity. Here we show that activation of endothelial caspase-9 after hypoxia-ischemia is a critical event in subsequent dysfunction of the blood-retina barrier, using a panel of interrelated ophthalmic in vivo imaging measures in a mouse model of retinal vein occlusion (RVO). Rapid nonapoptotic activation of caspase-9 and its downstream effector caspase-7 in endothelial cells promotes capillary ischemia and retinal neurodegeneration. Topical eye-drop delivery of a highly selective caspase-9 inhibitor provides morphological and functional retinal protection. Inducible endothelial-specific caspase-9 deletion phenocopies this protection, with attenuated retinal edema, reduced inflammation and preserved neuroretinal morphology and function following RVO. These results reveal a non-apoptotic function of endothelial caspase-9 which regulates blood-retina barrier integrity and neuronal survival, and identify caspase-9 as a therapeutic target in neurovascular disease.

Retinal vein occlusion can cause blindness, and features neuronal dysfunction, inflammation and breakdown of vascular integrity. Here the authors report a non-apoptotic role of endothelial caspase-9 in regulating blood-retina barrier integrity and neuronal survival, which can be therapeutically targeted in a mouse model of retinal vein occlusion.

Endothelial tight junctions and their regulatory signaling pathways in vascular homeostasis and disease

Endothelial tight junctions (TJs) regulate the transport of water, ions, and molecules through the paracellular pathway, serving as an important barrier in blood vessels and maintaining vascular homeostasis. In endothelial cells (ECs), TJs are highly dynamic structures that respond to multiple external stimuli and pathological conditions. Alterations in the expression, distribution, and structure of endothelial TJs may lead to many related vascular diseases and pathologies. In this review, we provide an overview of the assessment methods used to evaluate endothelial TJ barrier function both in vitro and in vivo and describe the composition of endothelial TJs in diverse vascular systems and ECs. More importantly, the direct phosphorylation and dephosphorylation of TJ proteins by intracellular kinases and phosphatases, as well as the signaling pathways involved in the regulation of TJs, including and the protein kinase C (PKC), PKA, PKG, Ras homolog gene family member A (RhoA), mitogen-activated protein kinase (MAPK), phosphatidylinositol 3-kinase (PI3K)/Akt, and Wnt/β-catenin pathways, are discussed. With great advances in this area, targeting endothelial TJs may provide novel treatment for TJ-related vascular pathologies.

Effect of ripasudil on diabetic macular edema

The current study aimed to address whether ripasudil, a Rho-associated coiled-coil containing protein kinase (ROCK) inhibitor developed to treat glaucoma and ocular hypertension (OH), improves diabetic macular edema (DME) since it is known that ROCK upregulates vascular endothelial growth factor. We retrospectively investigated the foveal thickness (FT) measured by spectral-domain optical coherence tomography, visual acuity (VA), and intraocular pressure (IOP) in 12 eyes with DME that received ripasudil treatment for primary open-angle glaucoma or OH and compared them with 14 eyes that received no treatment. One month after ripasudil therapy, the mean FT decreased significantly from 439 ± 72 µm to 395 ± 62 µm (P = 0.003); this change was significantly different from that in the controls, in which the mean FT increased by 1 ± 39 µm (P = 0.01). Ripasudil also caused a significant decrease in IOP from 17.3 ± 5.2 mmHg to 14.6 ± 4.0 mmHg (P = 0.02); this change was significantly greater than that in the controls, in which IOP changed by 0.0 ± 1.6 mmHg (P < 0.008). There was no significant difference in the VA changes between groups. Our results suggested that ripasudil may have positive effects on both IOP and DME.