Nipradilol promotes axon regeneration through S-nitrosylation of PTEN in retinal ganglion cells

Neuroprotection of Rodent and Human Retinal Ganglion Cells In Vitro/Ex Vivo by the Hybrid Small Molecule SA-2

The mechanisms underlying the neuroprotective effects of the hybrid antioxidant-nitric oxide donating compound SA-2 in retinal ganglion cell (RGC) degeneration models were evaluated. The in vitro trophic factor (TF) deprivation model in primary rat RGCs and ex vivo human retinal explants were used to mimic glaucomatous neurodegeneration. Cell survival was assessed after treatment with vehicle or SA-2. In separate experiments, tert-Butyl hydroperoxide (TBHP) and endothelin-3 (ET-3) were used in ex vivo rat retinal explants and primary rat RGCs, respectively, to induce oxidative damage. Mitochondrial and intracellular reactive oxygen species (ROS) were assessed following treatments. In the TF deprivation model, SA-2 treatment produced a significant decrease in apoptotic and dead cell counts in primary RGCs and a significant increase in RGC survival in ex vivo human retinal explants. In the oxidative stress-induced models, a significant decrease in the production of ROS was observed in the SA-2-treated group compared to the vehicle-treated group. Compound SA-2 was neuroprotective against various glaucomatous insults in the rat and human RGCs by reducing apoptosis and decreasing ROS levels. Amelioration of mitochondrial and cellular oxidative stress by SA-2 may be a potential therapeutic strategy for preventing neurodegeneration in glaucomatous RGCs.

Effect of Latanoprostene Bunod on Optic Nerve Head Blood Flow

SIGNIFICANCE

Topical latanoprostene bunod increases capillary oxygen saturation and blood volume at the optic nerve head in healthy individuals.

PURPOSE

This study aimed to evaluate the effect of topical latanoprostene bunod on optic nerve blood volume and oxygen saturation in a population of healthy participants.

METHODS

In this prospective double-blind crossover study, 23 healthy participants aged from 21 to 62 years were recruited. Optic nerve head capillary blood volume (ONHvol) and oxygen saturation (ONHSaO2) baselines were measured over a period of 2 hours using multichannel spectroscopic reflectometry and were remeasured after a 7-day once-daily instillation regimen of either latanoprost 0.005% or latanoprostene bunod 0.024%. After a 30-day washout period, participants were crossed over to the alternate product, and measurements were repeated. Participants were used as their own baselines to calculate variation in ONHvol and ONHSaO2 across time and pharmacological agents. The Friedman test was used to establish significant differences in optic nerve head parameters from baseline values, and Conover post hoc analysis was carried for multiple between-group comparisons.

RESULTS

Latanoprostene bunod 0.024% induced a significant increase of 4% in ONHSaO2 compared with latanoprost 0.005% (P < .001). Furthermore, latanoprostene bunod increased ONHvol levels by more than twofold at all time points (P < .001 at T60, T90, and T120). The increase in ONHvol was 66.2% higher than levels achieved with latanoprost at T60 (P = .001), 47% higher at T90 (P < .001), and 45% higher at T120 (P < .01).

CONCLUSIONS

Latanoprostene bunod 0.024% induces a significant increase in optic nerve head blood volume and oxygen saturation in healthy subjects, when compared with latanoprost 0.005%. Future studies are needed to evaluate whether similar responses are elicited in patients suffering from glaucomatous optic neuropathy.

Nitric oxide donating anti-glaucoma drugs: advances and prospects

Glaucoma is a disease that causes irreversible blindness. Reducing intraocular pressure (IOP) is the main treatment at present. Nitric oxide (NO), an endogenous gas signaling molecule, can increase aqueous humor outflow facility, inhibit aqueous humor production thereby reducing IOP, as well as regulate eye blood flow and protect the optic nerve. Therefore, NO donating anti-glaucoma drugs have broad research prospects. In this review, we summarize NO-mediated therapy for glaucoma, and the state of the art of some NO donating molecules, including latanoprostene bunod in market and some other candidate compounds, for the intervention of glaucoma, as well as prospects and challenges ahead in this field.

Simvastatin Enhances Muscle Regeneration Through Autophagic Defect-Mediated Inflammation and mTOR Activation in G93ASOD1 Mice

Amyotrophic lateral sclerosis is a fatal neurodegenerative disease characterised by the selective loss of motor neurons, muscular atrophy, and degeneration. Statins, as 3-hydroxy-3-methylglutaryl coenzyme A reductase inhibitors, are the most widely prescribed drugs to lower cholesterol levels and used for the treatment of cardiovascular and cerebrovascular diseases. However, statins are seldom used in muscular diseases, primarily because of their rare statin-associated myopathy. Recently, statins have been shown to reduce muscular damage and improve its function. Here, we investigated the role of statins in myopathy using G93ASOD1 mice. Our results indicated that simvastatin significantly increased the autophagic flux defect and increased inflammation in the skeletal muscles of G93ASOD1 mice. We also found that increased inflammation correlated with aggravated muscle atrophy and fibrosis. Nevertheless, long-term simvastatin treatment promoted the regeneration of damaged muscle by activating the mammalian target of rapamycin pathway. However, administration of simvastatin did not impede vast muscle degeneration and movement dysfunction resulting from the enhanced progressive impairment of the neuromuscular junction. Together, our findings highlighted that simvastatin exacerbated skeletal muscle atrophy and denervation in spite of promoting myogenesis in damaged muscle, providing new insights into the selective use of statin-induced myopathy in ALS.

The nitric oxide-guanylate cyclase pathway and glaucoma

Glaucoma is a prevalent optic neuropathy characterized by the progressive dysfunction and loss of retinal ganglion cells (RGCs) and their optic nerve axons, which leads to irreversible visual field loss. Multiple risk factors for the disease have been identified, but elevated intraocular pressure (IOP) remains the primary risk factor amenable to treatment. Reducing IOP however does not always prevent glaucomatous neurodegeneration, and many patients progress with the disease despite having IOP in the normal range. There is increasing evidence that nitric oxide (NO) is a direct regulator of IOP and that dysfunction of the NO-Guanylate Cyclase (GC) pathway is associated with glaucoma incidence. NO has shown promise as a novel therapeutic with targeted effects that: 1) lower IOP; 2) increase ocular blood flow; and 3) confer neuroprotection. The various effects of NO in the eye appear to be mediated through the activation of the GC- guanosine 3:5'-cyclic monophosphate (cGMP) pathway and its effect on downstream targets, such as protein kinases and Ca²⁺ channels. Although NO-donor compounds are promising as therapeutics for IOP regulation, they may not be ideal to harness the neuroprotective potential of NO signaling. Here we review evidence that supports direct targeting of GC as a novel pleiotrophic treatment for the disease, without the need for direct NO application. The identification and targeting of other factors that contribute to glaucoma would be beneficial to patients, particularly those that do not respond well to IOP-dependent interventions.

Epigenetics and Signaling Pathways in Glaucoma

Glaucoma is the most common cause of irreversible blindness worldwide. This neurodegenerative disease becomes more prevalent with aging, but predisposing genetic and environmental factors also contribute to increased risk. Emerging evidence now suggests that epigenetics may also be involved, which provides potential new therapeutic targets. These three factors work through several pathways, including TGF-β, MAP kinase, Rho kinase, BDNF, JNK, PI-3/Akt, PTEN, Bcl-2, Caspase, and Calcium-Calpain signaling. Together, these pathways result in the upregulation of proapoptotic gene expression, the downregulation of neuroprotective and prosurvival factors, and the generation of fibrosis at the trabecular meshwork, which may block aqueous humor drainage. Novel therapeutic agents targeting these pathway members have shown preliminary success in animal models and even human trials, demonstrating that they may eventually be used to preserve retinal neurons and vision.