Axonal Protection by Netarsudil, a ROCK Inhibitor, Is Linked to an AMPK-Autophagy Pathway in TNF-Induced Optic Nerve Degeneration

The Interplay between MiR-134/BDNF and LKB1/AMPK/SIRT1 Accentuates the Antidepressant Efficacy of Empagliflozin in Ovariectomized Rats

Major depressive disorder (MDD) is considered a major cause of suicide worldwide. As previous studies revealed that neuroinflammation is a significant factor in the etiology of MDD, this study proposed to unravel the possible antidepressant effect of Empagliflozin (EMPA) through targeting miRNA-134 (miR-134)/brain-derived neurotrophic factor (BDNF) and liver kinase B1 (LKB1)/adenosine 5'-monophosphate-activated protein kinase (AMPK)/silent information regulator 1 (SIRT1) axes in ovariectomized (OVX) female rats. Rats were assigned randomly to four groups: Sham operation (SO), OVX, OVX + EMPA (10 mg/kg/day, p.o.), and OVX + EMPA + Dorsomorphin (DORSO) (25 μg/day/rat, i.v.). Drugs were administered for 28 days after 2 weeks of surgery. EMPA debilitated OVX-induced depressive-like behavior by mitigating the immobility time in the tail suspension test and forced swimming test. Moreover, EMPA curtailed OVX-induced alterations of serum estradiol, hippocampal serotonin, miR-134 expression, as well as BDNF. EMPA also dwindled OVX-induced changes of hippocampal p-LKB1/LKB1, p-AMPK/AMPK, SIRT1, and inflammatory markers (nuclear factor-kappa-B, interleukin-1 beta, interleukin-6, and tumor necrosis factor alpha). Additionally, the EMPA-treated group exhibited marked improvement in different brain regions' histopathology. However, DORSO coadministration reversed most of EMPA's beneficial effects. The current study displayed the modulatory role of EMPA on miR-134/BDNF and LKB1/AMPK/SIRT1 axes, thus offering a partial explanation of its antidepressant efficacy and proposing EMPA as a novel therapeutic avenue for MDD.

Review of evidence for treatments of acute non arteritic anterior ischemic optic neuropathy

OBJECTIVE

To review treatment modalities that have been studied in acute non arteritic anterior ischemic optic neuropathy (NAION).

METHODS

We performed a comprehensive literature search of English language publications in the last 5 years, with human species and NAION. Articles were reviewed to identify those that described original research on treatment of acute NAION. Study type, setting, duration, interventions, and results were extracted and articles were reviewed for biases and limitations.

RESULTS

We identified 22 kinds of treatment varying by compound and modality. These include topical, intravitreal, and systemic drugs as well as surgical approaches. Evidence for efficacy ranges from expert opinion to randomized control trials.

CONCLUSIONS

Although several treatments are utilized in practice, none of these have high quality evidence of efficacy to improve visual outcomes.  Continued collaborative research is necessary to complete high quality studies in order identify effective therapies for this rare and blinding disease.

Insights into Calpain Activation and Rho-ROCK Signaling in Parkinson's Disease and Aging

Parkinson's disease (PD), a progressive neurodegenerative disease, has no cure, and current therapies are not effective at halting disease progression. The disease affects mid-brain dopaminergic neurons and, subsequently, the spinal cord, contributing to many debilitating symptoms associated with PD. The GTP-binding protein, Rho, plays a significant role in the cellular pathology of PD. The downstream effector of Rho, Rho-associated kinase (ROCK), plays multiple functions, including microglial activation and induction of inflammatory responses. Activated microglia have been implicated in the pathology of many neurodegenerative diseases, including PD, that initiate inflammatory responses, leading to neuron death. Calpain expression and activity is increased following glial activation, which triggers the Rho-ROCK pathway and induces inflammatory T cell activation and migration as well as mediates toxic α-synuclein (α-syn) aggregation and neuron death, indicating a pivotal role for calpain in the inflammatory and degenerative processes in PD. Increased calpain activity and Rho-ROCK activation may represent a new mechanism for increased oxidative damage in aging. This review will summarize calpain activation and the role of the Rho-ROCK pathway in oxidative stress and α-syn aggregation, their influence on the neurodegenerative process in PD and aging, and possible strategies and research directions for therapeutic intervention.

Axonal protection by combination of ripasudil and brimonidine with upregulation of p-AMPK in TNF-induced optic nerve degeneration

PURPOSE

The ROCK inhibitor ripasudil hydrochloride hydrate was shown to have axonal protective effects in TNF-induced optic nerve degeneration. The α2-adrenoreceptor agonist brimonidine was also shown to exert axonal protection. The current study aimed to elucidate whether additive axonal protection was achieved by the simultaneous injection of ripasudil and brimonidine and examine the association with AMPK activation.

METHODS

Intravitreal administration was performed in the following groups: PBS, TNF, or TNF with ripasudil, with brimonidine, or with a combination of ripasudil and brimonidine. Axon numbers were counted to evaluate the effects against axon loss. Immunoblot analysis was performed to examine phosphorylated AMPK expression in optic nerves, and immunohistochemical analysis was performed to evaluate the expression levels of p-AMPK and neurofilament in the optic nerve.

RESULTS

Both ripasudil alone or brimonidine alone resulted in significant neuroprotection against TNF-induced axon loss. The combination of ripasudil and brimonidine showed additive protective effects. Combined ripasudil and brimonidine plus TNF significantly upregulated p-AMPK levels in the optic nerve compared with the TNF groups. Immunohistochemical analysis revealed that p-AMPK is present in axons and enhanced by combination therapy.

CONCLUSION

The combination of ripasudil and brimonidine may have additive protective effects compared with single-agent treatment alone. These protective effects may be at least partially associated with AMPK activation.

Molecular aspects of optic nerve autophagy in glaucoma

The optic nerve consists of the glia, vessels, and axons including myelin and axoplasm. Since axonal degeneration precedes retinal ganglion cell death in glaucoma, the preceding axonal degeneration model may be helpful for understanding the molecular mechanisms of optic nerve degeneration. Optic nerve samples from these models can provide information on several aspects of autophagy. Autophagosomes, the most typical organelles expressing autophagy, are found much more frequently inside axons than around the glia. Thus, immunoblot findings from the optic nerve can reflect the autophagy state in axons. Autophagic flux impairment may occur in degenerating optic nerve axons, as in other central nervous system neurodegenerative diseases. Several molecular candidates are involved in autophagy enhancement, leading to axonal protection. This concept is an attractive approach to the prevention of further retinal ganglion cell death. In this review, we describe the factors affecting autophagy, including nicotinamide riboside, p38, ULK, AMPK, ROCK, and SIRT1, in the optic nerve and propose potential methods of axonal protection via enhancement of autophagy.

Targeting autophagy with small-molecule activators for potential therapeutic purposes

Autophagy is well-known to be a lysosome-mediated catabolic process for maintaining cellular and organismal homeostasis, which has been established with many links to a variety of human diseases. Compared with the therapeutic strategy for inhibiting autophagy, activating autophagy seems to be another promising therapeutic strategy in several contexts. Hitherto, mounting efforts have been made to discover potent and selective small-molecule activators of autophagy to potentially treat human diseases. Thus, in this perspective, we focus on summarizing the complicated relationships between defective autophagy and human diseases, and further discuss the updated progress of a series of small-molecule activators targeting autophagy in human diseases. Taken together, these inspiring findings would provide a clue on discovering more small-molecule activators of autophagy as targeted candidate drugs for potential therapeutic purposes.

Phase 3 Clinical Trial Comparing the Safety and Efficacy of Netarsudil to Ripasudil in Patients with Primary Open-Angle Glaucoma or Ocular Hypertension: Japan Rho Kinase Elevated Intraocular Pressure Treatment Trial (J-ROCKET)

INTRODUCTION

A clinical trial evaluated ocular hypotensive efficacy and safety of netarsudil 0.02% once daily (QD) relative to ripasudil 0.4% twice daily (BID).

METHODS

This was a single-masked, randomized, phase 3, superiority study. Japanese patients were randomized to either the netarsudil 0.02% group or the ripasudil 0.4% group in a 1:1 ratio and treated for 4 weeks. The primary efficacy variable was mean diurnal intraocular pressure (IOP) (average of diurnal time points at 09:00, 11:00, and 16:00) at Week 4.

RESULTS

A total of 245 patients were included in the primary analysis. At Week 4, least squares (LS) mean of diurnal IOP adjusted for baseline was 15.96 and 17.71 mmHg in the netarsudil 0.02% and ripasudil 0.4% groups, respectively, demonstrating the superiority of netarsudil 0.02% QD over ripasudil 0.4% BID by a margin of - 1.74 mmHg (p < 0.0001). Mean reduction from baseline in mean diurnal IOP at Week 4 was 4.65 and 2.98 mmHg, respectively. Adverse events (AEs) occurred less frequently in netarsudil 0.02% than in ripasudil 0.4%, with the incidence of ocular AEs being 59.8% and 66.7%, respectively. The most frequently reported AE was conjunctival hyperemia in both groups, with an incidence of 54.9% and 62.6%, respectively. No serious eye-related AEs were reported.

CONCLUSION

Netarsudil ophthalmic solution 0.02% dosed QD (p.m.) was well tolerated and more effective in reducing IOP than ripasudil ophthalmic solution 0.4% dosed BID. Netarsudil 0.02% QD may become an important option for the treatment of Japanese patients with primary open-angle glaucoma (POAG) or ocular hypertension (OHT).

TRIAL REGISTRATION

ClinicalTrials.gov identifier, NCT04620135.

Axonal Protection by Oral Nicotinamide Riboside Treatment with Upregulated AMPK Phosphorylation in a Rat Glaucomatous Degeneration Model

Nicotinamide riboside (NR), a precursor of nicotinamide adenine dinucleotide (NAD+), has been studied to support human health against metabolic stress, cardiovascular disease, and neurodegenerative disease. In the present study, we investigated the effects of oral NR on axonal damage in a rat ocular hypertension model. Intraocular pressure (IOP) elevation was induced by laser irradiation and then the rats received oral NR of 1000 mg/kg/day daily. IOP elevation was seen 7, 14, and 21 days after laser irradiation compared with the controls. We confirmed that oral NR administration significantly increased NAD+ levels in the retina. After 3-week oral administration of NR, morphometric analysis of optic nerve cross-sections showed that the number of axons was protected compared with that in the untreated ocular hypertension group. Oral NR administration significantly prevented retinal ganglion cell (RGC) fiber loss in retinal flat mounts, as shown by neurofilament immunostaining. Immunoblotting samples from the optic nerves showed that oral NR administration augmented the phosphorylated adenosine monophosphate-activated protein kinase (p-AMPK) level in rats with and without ocular hypertension induction. Immunohistochemical analysis showed that some p-AMPK-immunopositive fibers were colocalized with neurofilament immunoreactivity in the control group, and oral NR administration enhanced p-AMPK immunopositivity. Our findings suggest that oral NR administration protects against glaucomatous RGC axonal degeneration with the possible upregulation of p-AMPK.

[The value of lamina cribrosa in the diagnosis and treatment of glaucoma. Remodeling of lamina cribrosa collagen and approaches to its therapeutic treatment]

Among the first structures suffering damage with an increase in intraocular pressure (IOP) and in early stage of glaucoma are the lamina cribrosa (LC) and peripapillary sclera (ppScl). Changes in these structures occur at the molecular and cellular level. Extracellular matrix (ECM) is the basis of connective tissue, provides mechanical support for the cells, facilitates intercellular interactions and transport of chemicals, including in LC and ppScl. Mechanical stress causes remodeling and disorganization of the ECM, which leads to changes in the structure of the tissue itself, an increase in its rigidity and a decrease in elasticity. Taking into account the molecular and cellular mechanisms of damage to LC and ppScl, various researchers have developed strategies and tactics for therapeutic intervention on these structures, contributing to a decrease in ECM secretion and, as a consequence, suspension of their remodeling. These approaches may in the future form the basis for the treatment of glaucomatous optic neuropathy.

A systematic review on the effects of ROCK inhibitors on proliferation and/or differentiation in human somatic stem cells: A hypothesis that ROCK inhibitors support corneal endothelial healing via acting on the limbal stem cell niche

Rho kinase inhibitors (ROCKi) have attracted growing multidisciplinary interest, particularly in Ophthalmology where the question as to how they promote corneal endothelial healing remains unresolved. Concurrently, stem cell biology has rapidly progressed in unravelling drivers of stem cell (SC) proliferation and differentiation, where mechanical niche factors and the actin cytoskeleton are increasingly recognized as key players. There is mounting evidence from the study of the peripheral corneal endothelium that supports the likelihood of an internal limbal stem cell niche. The possibility that ROCKi stimulate the endothelial SC niche has not been addressed. Furthermore, there is currently a paucity of data that directly evaluates whether ROCKi promotes corneal endothelial healing by acting on this limbal SC niche located near the transition zone. Therefore, we performed a systematic review examining the effects ROCKi on the proliferation and differentiation of human somatic SC, to provide insight into its effects on various human SC populations. An appraisal of electronic searches of four databases identified 1 in vivo and 58 in vitro studies (36 evaluated proliferation while 53 examined differentiation). Types of SC studied included mesenchymal (n = 32), epithelial (n = 11), epidermal (n = 8), hematopoietic and other (n = 8). The ROCK 1/2 selective inhibitor Y-27632 was used in almost all studies (n = 58), while several studies evaluated ≥2 ROCKi (n = 4) including fasudil, H-1152, and KD025. ROCKi significantly influenced human somatic SC proliferation in 81% of studies (29/36) and SC differentiation in 94% of studies (50/53). The present systemic review highlights that ROCKi are influential in regulating human SC proliferation and differentiation, and provides evidence to support the hypothesis that ROCKi promotes corneal endothelial division and maintenance via acting on the inner limbal SC niche.

Remodeling of the Lamina Cribrosa: Mechanisms and Potential Therapeutic Approaches for Glaucoma

Glaucomatous optic neuropathy is the leading cause of irreversible blindness in the world. The chronic disease is characterized by optic nerve degeneration and vision field loss. The reduction of intraocular pressure remains the only proven glaucoma treatment, but it does not prevent further neurodegeneration. There are three major classes of cells in the human optic nerve head (ONH): lamina cribrosa (LC) cells, glial cells, and scleral fibroblasts. These cells provide support for the LC which is essential to maintain healthy retinal ganglion cell (RGC) axons. All these cells demonstrate responses to glaucomatous conditions through extracellular matrix remodeling. Therefore, investigations into alternative therapies that alter the characteristic remodeling response of the ONH to enhance the survival of RGC axons are prevalent. Understanding major remodeling pathways in the ONH may be key to developing targeted therapies that reduce deleterious remodeling.