Systemic Treatment with Nicotinamide Riboside Is Protective in Two Mouse Models of Retinal Ganglion Cell Damage

Biomechanic, proteomic and miRNA transcriptional changes in the trabecular meshwork of primates injected with intravitreal triamcinolone

Although biomechanical changes of the trabecular meshwork (TM) are important to the pathogenesis of glucocorticoids-induced ocular hypertension (GC-OHT), there is a knowledge gap in the underlying molecular mechanisms of the development of it. In this study, we performed intravitreal triamcinolone injection (IVTA) in one eye of 3 rhesus macaques. Following IVTA, we assessed TM stiffness using atomic force microscopy and investigated changes in proteomic and miRNA expression profiles. One of 3 macaques developed GC-OHT with a difference in intraocular pressure of 4.2 mmHg and a stiffer TM with a mean increase in elastic moduli of 0.60 kPa versus the non-injected control eye. In the IVTA-treated eyes, proteins associated with extracellular matrix remodeling, cytoskeletal rearrangement, and mitochondrial oxidoreductation were significantly upregulated. The significantly upregulated miR-29b and downregulated miR-335-5p post-IVTA supported the role of oxidative stress and mitophagy in the GC-mediated biomechanical changes in TM, respectively. The significant upregulation of miR-15/16 cluster post-IVTA may indicate a resultant TM cell apoptosis contributing to the increase in outflow resistance. Despite the small sample size, these results expand our knowledge of GC-mediated responses in the TM and furthermore, may help explain steroid responsiveness in clinical settings.

NAD+ and Niacin Supplementation as Possible Treatments for Glaucoma and Age-Related Macular Degeneration: A Narrative Review

Glaucoma and age-related macular degeneration (AMD) are progressive retinal diseases characterized by increased oxidative stress, inflammation, and mitochondrial dysfunction. This review investigates the potential therapeutic benefits of NAD+ and niacin supplementation in managing glaucoma and AMD. A literature search was conducted encompassing keywords such as "niacin", "NAD", "glaucoma", "AMD", and "therapeutics". NAD+ depletion is associated with increased oxidative stress and mitochondrial dysfunction in glaucoma and AMD. Niacin, a precursor to NAD+, has shown promise in replenishing NAD+ levels, improving choroidal blood flow, and reducing oxidative damage. Animal studies in glaucoma models indicate that nicotinamide (NAM) supplementation preserves RGC density and function. Large-scale population-based studies indicate an inverse correlation between niacin intake and glaucoma prevalence, suggesting a preventative role. Randomized controlled trials assessing niacin supplementation showed significant improvements in visual field sensitivity and inner retinal function, with a dose-dependent relationship. In AMD, nicotinamide supplementation may improve rod cell function and protect against oxidative stress-induced damage. Cross-sectional studies reveal that individuals with AMD have a lower dietary intake of niacin. Further studies suggest niacin's role in improving choroidal blood flow and dilating retinal arterioles, potentially mitigating ischemic damage and oxidative stress in AMD. Beyond current management strategies, NAD+ and niacin supplementation may offer novel therapeutic avenues for glaucoma and AMD. Further research is warranted to elucidate their efficacy and safety in clinical settings.

New insights into metabolism dysregulation after TBI

Traumatic brain injury (TBI) remains a leading cause of death and disability that places a great physical, social, and financial burden on individuals and the health system. In this review, we summarize new research into the metabolic changes described in clinical TBI trials, some of which have already shown promise for informing injury classification and staging. We focus our discussion on derangements in glucose metabolism, cell respiration/mitochondrial function and changes to ketone and lipid metabolism/oxidation to emphasize potentially novel biomarkers for clinical outcome prediction and intervention and offer new insights into possible underlying mechanisms from preclinical research of TBI pathology. Finally, we discuss nutrition supplementation studies that aim to harness the gut/microbiome-brain connection and manipulate systemic/cellular metabolism to improve post-TBI recovery. Taken together, this narrative review summarizes published TBI-associated changes in glucose and lipid metabolism, highlighting potential metabolite biomarkers for clinical use, the cellular processes linking these markers to TBI pathology as well as the limitations and future considerations for TBI "omics" work.

Nicotinamide: Bright Potential in Glaucoma Management

BACKGROUND

Glaucoma is a major cause of incurable ocular morbidity and poses significant challenges in its management due to the limited treatment options and potential adverse effects. Nicotinamide, a naturally occurring diet-rich nutrient, has emerged as a promising therapeutic agent for glaucoma, offering neuroprotective effects and the potential modulation of intraocular pressure (IOP) regulation pathways. This comprehensive review sought to analyze the current literature on nicotinamide in glaucoma management, exploring its mechanisms of action, efficacy, and safety profile.

METHODS

A systematic search of the PubMed database was conducted to identify relevant records on the therapeutic actions of nicotinamide in ocular hypertension and glaucoma. Publications evaluating nicotinamide's effects on retinal ganglion cells (RGCs), optic nerve function, IOP regulation, and neuroinflammatory pathways were included.

RESULTS

The literature review revealed the preclinical evidence supporting nicotinamide's neuroprotective effects on RGCs, the preservation of optic nerve integrity, and the modulation of glaucoma-associated neuroinflammation. Additionally, nicotinamide may exert IOP-lowering effects through its influence on ocular blood flow and aqueous humor dynamics.

CONCLUSIONS

Nicotinamide holds promise as a novel therapeutic approach in glaucoma management, offering potential neuroprotective and IOP-lowering effects. The authors recommend more research to determine the nicotinamide efficacy, safe dosing parameters, and any long-term safety concerns in glaucoma patients.

Programmed axon death: a promising target for treating retinal and optic nerve disorders

Programmed axon death is a druggable pathway of axon degeneration that has garnered considerable interest from pharmaceutical companies as a promising therapeutic target for various neurodegenerative disorders. In this review, we highlight mechanisms through which this pathway is activated in the retina and optic nerve, and discuss its potential significance for developing therapies for eye disorders and beyond. At the core of programmed axon death are two enzymes, NMNAT2 and SARM1, with pivotal roles in NAD metabolism. Extensive preclinical data in disease models consistently demonstrate remarkable, and in some instances, complete and enduring neuroprotection when this mechanism is targeted. Findings from animal studies are now being substantiated by genetic human data, propelling the field rapidly toward clinical translation. As we approach the clinical phase, the selection of suitable disorders for initial clinical trials targeting programmed axon death becomes crucial for their success. We delve into the multifaceted roles of programmed axon death and NAD metabolism in retinal and optic nerve disorders. We discuss the role of SARM1 beyond axon degeneration, including its potential involvement in neuronal soma death and photoreceptor degeneration. We also discuss genetic human data and environmental triggers of programmed axon death. Lastly, we touch upon potential therapeutic approaches targeting NMNATs and SARM1, as well as the nicotinamide trials for glaucoma. The extensive literature linking programmed axon death to eye disorders, along with the eye's suitability for drug delivery and visual assessments, makes retinal and optic nerve disorders strong contenders for early clinical trials targeting programmed axon death.

Protective Effect of Nicotinamide Riboside on Glucocorticoid-Induced Glaucoma: Mitigating Mitochondrial Damage and Extracellular Matrix Deposition

Purpose

Glucocorticoid-induced glaucoma (GIG) is a prevalent complication associated with glucocorticoids (GCs), resulting in irreversible blindness. GIG is characterized by the abnormal deposition of extracellular matrix (ECM) in the trabecular meshwork (TM), elevation of intraocular pressure (IOP), and loss of retinal ganglion cells (RGCs). The objective of this study is to investigate the effects of nicotinamide riboside (NR) on TM in GIG.

Methods

Primary human TM cells (pHTMs) and C57BL/6J mice responsive to GCs were utilized to establish in vitro and in vivo GIG models, respectively. The study assessed the expression of ECM-related proteins in TM and the functions of pHTMs to reflect the effects of NR. Mitochondrial morphology and function were also examined in the GIG cell model. GIG progression was monitored through IOP, RGCs, and mitochondrial morphology. Intracellular nicotinamide adenine dinucleotide (NAD+) levels of pHTMs were enzymatically assayed.

Results

NR significantly prevented the expression of ECM-related proteins and alleviated dysfunction in pHTMs after dexamethasone treatment. Importantly, NR protected damaged ATP synthesis, preventing overexpression of mitochondrial reactive oxygen species (ROS), and also protect against decreased mitochondrial membrane potential induced by GCs in vitro. In the GIG mouse model, NR partially prevented the elevation of IOP and the loss of RGCs. Furthermore, NR effectively suppressed the excessive expression of ECM-associated proteins and mitigated mitochondrial damage in vivo.

Conclusions

Based on the results, NR effectively enhances intracellular levels of NAD+, thereby mitigating abnormal ECM deposition and TM dysfunction in GIG by attenuating mitochondrial damage induced by GCs. Thus, NR has promising potential as a therapeutic candidate for GIG treatment.

Optimizing retinal ganglion cell nuclear staining for automated cell counting

The retinal ganglion cells (RGCs) serve as the critical pathway for transmitting visual information from the retina to the brain, yet they can be dramatically impacted by diseases such as glaucoma. When investigating disease processes affecting RGCs in mouse models, accurately quantifying affected cells becomes essential. However, the use of pan RGC markers like RBPMS or THY1 presents challenges in accurate total cell counting. While Brn3a serves as a reliable RGC nuclear marker for automated counting, it fails to encompass all RGC subtypes in mice. To address this limitation and enable precise automated counting, our research endeavors to develop a method for labeling nuclei in all RGC subtypes. Investigating RGC subtypes labeled with the nuclear marker POU6F2 revealed that numerous RGCs unlabeled by Brn3a were, in fact, labeled with POU6F2. We hypothesize that using antibodies against both Brn3a and POU6F2 would label virtually all RGC nuclei in the mouse retina. Our experiments confirmed that staining retinas with both markers resulted in the labeling of all RGCs. Additionally, when using the cell body marker RBPMS known to label all mouse RGCs, all RBPMS-labeled cells also exhibited Brn3a or POU6F2 labeling. This combination of Brn3a and POU6F2 antibodies provides a pan-RGC nuclear stain, facilitating accurate automated counting by labeling cell nuclei in the retina.

Vitamin B3 Supplementation for Optic Neuropathies: A Comprehensive Review

Optic neuropathies, such as glaucoma, are some of the leading causes of irreversible blindness worldwide. There has been a lot of research for potential therapies that could attenuate and even reduce the impact of the pathological pathways that lead to the loss of retinal ganglion cells (RGCs). In recent years, vitamin B3 (nicotinamide) has gained some interest as a viable option for these neurodegenerative diseases due to its fundamental role in enhancing the mitochondria metabolism of the RGCs. This review focuses on elucidating the impact of vitamin B3 on retinal cells, especially when in a dysfunctional state like what happens in optic neuropathies, especially glaucoma. This review also summarizes the existing and future research on the clinical effects of vitamin B3 in these optic neuropathies, and determines appropriate recommendations regarding its dosing, efficacy, and eventual side effects.

The Role and Mechanism of Nicotinamide Riboside in Oxidative Damage and a Fibrosis Model of Trabecular Meshwork Cells

Purpose

To investigate the potential effects and mechanism of nicotinamide riboside (NR) on the oxidative stress and fibrosis model of human trabecular meshwork (HTM) cell line cells.

Methods

HTM cells were pretreated with NR, followed by the induction of oxidative injury and fibrosis by hydrogen peroxide (H2O2) and TGF-β2, respectively. Cell viability was tested using Hoechst staining and MTT assays, cell proliferation was assessed by EdU assay, and cell apoptosis was detected by flow cytometry and western blotting. DCFH-DA and DHE probes were used to measure the level of reactive oxygen species (ROS), and MitoTracker staining was used to measure the mitochondrial membrane potential (MMP). Fibrotic responses, including cell migration and deposition of extracellular matrix (ECM) proteins, were detected via Transwell assays, qRT-PCR, and immunoblotting.

Results

NR pretreatment improved the viability, proliferation, and MMP of H2O2-treated HTM cells. Compared to cells treated solely with H2O2, HTM cells treated with both NR and H2O2, exhibited a reduced rate of apoptosis and generation of ROS. Compared with H2O2 pretreatment, NR pretreatment upregulated expression of the JAK2/Stat3 pathway but inhibited mitogen-activated protein kinase (MAPK) pathway expression. Moreover, 10-ng/mL TGF-β2 promoted cell proliferation and migration, which were inhibited by NR pretreatment. Both qRT-PCR and immunoblotting showed that NR inhibited the expression of fibronectin in a TGF-β2-induced fibrosis model.

Conclusions

NR has a protective effect on oxidative stress and fibrosis in HTM cells, which may be related to the JAK2/Stat3 pathway and MAPK pathway.

Translational Relevance

Our research provides the ongoing data for potential therapy of NAD+ precursors in glaucoma.

Targeting NAD Metabolism for the Therapy of Age-Related Neurodegenerative Diseases

As the aging population continues to grow rapidly, age-related diseases are becoming an increasing burden on the healthcare system and a major concern for the well-being of elderly individuals. While aging is an inevitable process for all humans, it can be slowed down and age-related diseases can be treated or alleviated. Nicotinamide adenine dinucleotide (NAD) is a critical coenzyme or cofactor that plays a central role in metabolism and is involved in various cellular processes including the maintenance of metabolic homeostasis, post-translational protein modifications, DNA repair, and immune responses. As individuals age, their NAD levels decline, and this decrease has been suggested to be a contributing factor to the development of numerous age-related diseases, such as cancer, diabetes, cardiovascular diseases, and neurodegenerative diseases. In pursuit of healthy aging, researchers have investigated approaches to boost or maintain NAD levels. Here, we provide an overview of NAD metabolism and the role of NAD in age-related diseases and summarize recent progress in the development of strategies that target NAD metabolism for the treatment of age-related diseases, particularly neurodegenerative diseases.

Glaucoma: neuroprotection with NAD-based therapeutic interventions

Clinical evidence shows that intraocular hypertension is not the primary pathogenetic event of glaucoma, whereas early neurodegeneration of retinal ganglion cells (RGCs) represents a key therapeutic target. Unfortunately, failure of clinical trials with neuroprotective agents, in particular those testing the anti-excitotoxic drug memantine, generated widespread skepticism regarding the possibility of counteracting neurodegeneration during glaucoma. New avenues for neuroprotective approaches to counteract glaucoma evolution have been opened by the identification of a programmed axonal degeneration (PAD) program triggered by increased nicotinamide mononucleotide (NMN)/NAD concentration ratio. Positive results of proof-of-concept clinical studies based on sustaining axonal NAD homeostasis facilitated the design of Phase 2/3 trials. Here, I share my opinion on how neurodegeneration in glaucoma should be put into context, together with an appraisal of the pharmacological rationale of NAD-supporting therapies for use during glaucoma progression.

Unveiling Neuroprotection and Regeneration Mechanisms in Optic Nerve Injury: Insight from Neural Progenitor Cell Therapy with Focus on Vps35 and Syntaxin12

Axonal degeneration resulting from optic nerve damage can lead to the progressive death of retinal ganglion cells (RGCs), culminating in irreversible vision loss. We contrasted two methods for inducing optic nerve damage: optic nerve compression (ONCo) and optic nerve crush (ONCr). These were assessed for their respective merits in simulating traumatic optic neuropathies and neurodegeneration. We also administered neural progenitor cells (NPCs) into the subtenon space to validate their potential in mitigating optic nerve damage. Our findings indicate that both ONCo and ONCr successfully induced optic nerve damage, as shown by increases in ischemia and expression of genes linked to neuronal regeneration. Post NPC injection, recovery in the expression of neuronal regeneration-related genes was more pronounced in the ONCo model than in the ONCr model, while inflammation-related gene expression saw a better recovery in ONCr. In addition, the proteomic analysis of R28 cells in hypoxic conditions identified Vps35 and Syntaxin12 genes. Vps35 preserved the mitochondrial function in ONCo, while Syntaxin12 appeared to restrain inflammation via the Wnt/β-catenin signaling pathway in ONCr. NPCs managed to restore damaged RGCs by elevating neuroprotection factors and controlling inflammation through mitochondrial homeostasis and Wnt/β-catenin signaling in hypoxia-injured R28 cells and in both animal models. Our results suggest that ischemic injury and crush injury cause optic nerve damage via different mechanisms, which can be effectively simulated using ONCo and ONCr, respectively. Moreover, cell-based therapies such as NPCs may offer promising avenues for treating various optic neuropathies, including ischemic and crush injuries.

NAD+ metabolism and eye diseases: current status and future directions

Currently, there are no truly effective treatments for a variety of eye diseases, such as glaucoma, age-related macular degeneration (AMD), and inherited retinal degenerations (IRDs). These conditions have a significant impact on patients' quality of life and can be a burden on society. However, these diseases share a common pathological process of NAD+ metabolism disorders. They are either associated with genetically induced primary NAD+ synthase deficiency, decreased NAD+ levels due to aging, or enhanced NAD+ consuming enzyme activity during disease pathology. In this discussion, we explore the role of NAD+ metabolic disorders in the development of associated ocular diseases and the potential advantages and disadvantages of various methods to increase NAD+ levels. It is essential to carefully evaluate the possible adverse effects of these methods and conduct a more comprehensive and objective assessment of their function before considering their use.

The use of Nicotinamide and Nicotinamide riboside as an adjunct therapy in the treatment of glaucoma

Glaucoma is an optic neuropathy characterized by death of retinal ganglion cells (RGCs), which leads to progressive visual field loss and may result in blindness. Currently, the only available treatment to avoid or delay progression in glaucoma patients is to decrease intraocular pressure (IOP). However, despite adequate IOP control, approximately 25% of the patients continue to progress. To delay or prevent optic nerve damage in glaucoma, two forms of vitamin B3, nicotinamide (NAM) and nicotinamide riboside (NR) are emerging as viable adjuvant therapies. These compounds are nicotinamide adenine dinucleotide (NAD) precursors. NAD is essential for proper cell functioning and is involved in several metabolic activities, including protection against reactive oxygen species, contribution to the performance of various enzymes, and maintenance of mitochondrial function. Due to its beneficial effects and to the evidence of the reduction of NAD bioavailability with aging, researchers are seeking ways to replenish the cellular NAD pool, by administrating its precursors (NAM and NR), believing that it will reduce the RGC vulnerability to external stressors, such as increased IOP. This article attempts to analyze the current knowledge regarding the use of NAM and NR for the prevention and/or treatment of glaucoma.

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.

Nicotinamide Riboside, a Promising Vitamin B3 Derivative for Healthy Aging and Longevity: Current Research and Perspectives

Many studies have suggested that the oxidized form of nicotinamide adenine dinucleotide (NAD+) is involved in an extensive spectrum of human pathologies, including neurodegenerative disorders, cardiomyopathy, obesity, and diabetes. Further, healthy aging and longevity appear to be closely related to NAD+ and its related metabolites, including nicotinamide riboside (NR) and nicotinamide mononucleotide (NMN). As a dietary supplement, NR appears to be well tolerated, having better pharmacodynamics and greater potency. Unfortunately, NR is a reactive molecule, often unstable during its manufacturing, transport, and storage. Recently, work related to prebiotic chemistry discovered that NR borate is considerably more stable than NR itself. However, immediately upon consumption, the borate dissociates from the NR borate and is lost in the body through dilution and binding to other species, notably carbohydrates such as fructose and glucose. The NR left behind is expected to behave pharmacologically in ways identical to NR itself. This review provides a comprehensive summary (through Q1 of 2023) of the literature that makes the case for the consumption of NR as a dietary supplement. It then summarizes the challenges of delivering quality NR to consumers using standard synthesis, manufacture, shipping, and storage approaches. It concludes by outlining the advantages of NR borate in these processes.

From bench to behaviour: The role of lifestyle factors on intraocular pressure, neuroprotection, and disease progression in glaucoma

Current glaucoma management centres on intraocular pressure (IOP) reduction through pharmacological and surgical therapy. Despite broad interest in active management of glaucoma through lifestyle modifications, such recommendations have yet to be incorporated into standards of treatment. In this review, noteworthy preclinical studies and their translations in clinical populations are discussed to evaluate the roles of lifestyle factors in lowering IOP, offering neuroprotection, and/or slowing disease progression in those with open-angle glaucoma. Current literature suggests that aerobic exercise may be associated with neuroprotection and decreased disease progression. Mindfulness is associated with IOP reductions and neuroprotection. Caffeine is associated with mild, transient IOP elevations of uncertain significance. Nicotinamide supplementation is associated with neuroprotection and short-term visual function improvement. This review also highlights knowledge gaps regarding these factors and opportunities to strengthen our understanding of their role in glaucoma, including future preclinical studies that elucidate underlying mechanisms and clinical studies with additional functional endpoints and longer follow-up.

Innate immunity dysregulation in aging eye and therapeutic interventions

The prevalence of eye diseases increases considerably with age, resulting in significant vision impairment. Although the pathobiology of age-related eye diseases has been studied extensively, the contribution of immune-related changes due to aging remains elusive. In the eye, tissue-resident cells and infiltrating immune cells regulate innate responses during injury or infection. But due to aging, these cells lose their protective functions and acquire pathological phenotypes. Thus, dysregulated ocular innate immunity in the elderly increases the susceptibility and severity of eye diseases. Herein, we emphasize the impact of aging on the ocular innate immune system in the pathogenesis of infectious and non-infectious eye diseases. We discuss the role of age-related alterations in cellular metabolism, epigenetics, and cellular senescence as mechanisms underlying altered innate immune functions. Finally, we describe approaches to restore protective innate immune functions in the aging eye. Overall, the review summarizes our current understanding of innate immune functions in eye diseases and their dysregulation during aging.

New strategies for neuro protection in glaucoma

Glaucoma is a progressive, irreversible loss of retinal ganglion cells (RGCs) and axons that results in characteristic optic atrophy and corresponding progressive visual field defect. The exact mechanisms underlying glaucomatous neuron loss are not clear. The main risk factor for glaucoma onset and development is high intraocular pressure (IOP), however traditional IOP-lowering therapies are often not sufficient to prevent degeneration of RGCs and the vision loss may progress, indicating the need for complementary neuroprotective therapy. This review summarizes the progress for neuro protection in glaucoma in recent 5 years, including modulation of neuroinflammation, gene and cell therapy, dietary supplementation, and sustained-release system.

The Role of NAD+ and Nicotinamide (Vitamin B3) in Glaucoma: A Literature Review

Glaucoma is a collection of irreversible optic neuropathies which, if left untreated, lead to severe visual field loss. These diseases are a leading cause of blindness across the globe and are estimated to affect approximately 80 million people, particularly women and people of Asian descent (Quigley HA, Broman AT. 2006. Br J Ophthalmol 90: 262-267). This represents a major burden on healthcare systems worldwide. Recently, there has been increasing interest in the potential of nicotinamide (vitamin B3) as a novel option in the management of glaucoma. This review aims to analyse the currently available literature to determine whether there is evidence of an association between nicotinamide adenine dinucleotide (NAD⁺) and glaucomatous optic neuropathy, and whether nicotinamide has the potential to prevent or reverse these effects. The literature showed a strong connection between reduced NAD⁺ levels and retinal ganglion cell dysfunction through multiple different studies. There is also evidence of the positive effect of nicotinamide supplementation on retinal ganglion cell function in models of mouse glaucoma and in a study involving humans. Based on the literature findings, a recommendation has been made that more research into the efficacy, appropriate dosing, and potential side effects of nicotinamide supplementation is needed before it can be definitively determined whether it is appropriate for widespread prophylactic and therapeutic use against glaucoma in humans.

Molecular regulation of neuroinflammation in glaucoma: Current knowledge and the ongoing search for new treatment targets

Neuroinflammation relying on the inflammatory responses of glial cells has emerged as an impactful component of the multifactorial etiology of neurodegeneration in glaucoma. It has become increasingly evident that despite early adaptive and reparative features of glial responses, prolonged reactivity of the resident glia, along with the peripheral immune cells, create widespread toxicity to retinal ganglion cell (RGC) axons, somas, and synapses. As much as the synchronized responses of astrocytes and microglia to glaucoma-related stress or neuron injury, their bi-directional interactions are critical to build and amplify neuroinflammation and to dictate the neurodegenerative outcome. Although distinct molecular programs regulate somatic and axonal degeneration in glaucoma, inhibition of neurodegenerative inflammation can provide a broadly beneficial treatment strategy to rescue RGC integrity and function. Since inflammatory toxicity and mitochondrial dysfunction are converging etiological paths that can boost each other and feed into a vicious cycle, anti-inflammatory treatments may also offer a multi-target potential. This review presents an overview of the current knowledge on neuroinflammation in glaucoma with particular emphasis on the cell-intrinsic and cell-extrinsic factors involved in the reciprocal regulation of glial responses, the interdependence between inflammatory and mitochondrial routes of neurodegeneration, and the research aspects inspiring for prospective immunomodulatory treatments. With the advent of powerful technologies, ongoing research on molecular and functional characteristics of glial responses is expected to accumulate more comprehensive and complementary information and to rapidly move the field forward to safe and effective modulation of the glial pro-inflammatory activities, while restoring or augmenting the glial immune-regulatory and neurosupport functions.

Association between Daily Niacin Intake and Glaucoma: National Health and Nutrition Examination Survey

Background and Aims: To determine the relationship between dietary intake of niacin and glaucoma using the data from the 2005 to 2008 National Health and Nutrition Examination Survey (NHANES). Methods: Subjects aged 40 years and older who participated in the dietary intake interview and vision health questionnaire of NHANES were included in the study. Glaucoma diagnosis by self-report was utilized. Additionally, glaucoma diagnosis by fundus imaging and International Society Geographical and Epidemiological Ophthalmology (ISGEO) criteria was used in subjects with available qualified retinal imaging. Survey logistic regression analyses were used to examine the association between daily niacin consumption and glaucoma. Results: A total of 5768 participants were included in the study. There was a significant decrease in the crude odds of self-reported glaucoma in the third (OR 0.57, 95% Cl 0.43–0.76; p < 0.001) and fourth (OR 0.57, 95% Cl 0.37–0.90; p = 0.018) quartiles of daily niacin consumption, which equated to 21.01 to 28.22 mg/day and greater than 28.22 mg/day, respectively. A similar trend was found using fundus imaging of subjects with niacin intake in the third (OR 0.42, 95% Cl 0.25–0.72; p = 0.002) and fourth (OR 0.36, 95% Cl 0.20–0.67; p = 0.002) quartiles. After adjusting for covariates, the odds of glaucoma based on fundus imaging remained significantly lower for niacin intake in the third (OR 0.49, 95% Cl 0.28–0.87; p = 0.016) and fourth (OR 0.48, 95% Cl 0.26–0.89; p = 0.022) quartile levels. Using ISGEO criteria, there was no significant association between glaucoma and daily niacin consumption. Conclusions: Greater niacin intake may be associated with a lower chance of developing glaucoma.