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.

Comparison of minimally invasive glaucoma surgery with trabecular micro-bypass stent and microhook ab interno trabeculotomy performed in conjunction with cataract surgery.

AIM: To evaluate the effectuality and safety of cataract surgery combined with either ab interno trabeculotomy by the microhook (µLOT) or a single iStent® trabecular bypass implantation (iStent) in eyes with cataract and mild-to-moderate glaucoma. METHODS: This study enrolled subjects with mild-to-moderate open angle glaucoma with visually significant cataract who used two or more ophthalmic antiglaucoma agents between 60 and 90y of age. Patients underwent cataract surgery cooperated with either implantation of an iStent (iStent-phaco) or excisional goniotomy with the µLOT (µLOT-phaco). Patients underwent µLOT-phaco in the eye with lower the mean deviation, according to the Humphrey field analyzer, while iStent-phaco was carried out on the other eye. Intraocular pressure (IOP) pre- and post-surgery, alterations in anterior chamber flare (ACF), and corneal endothelial cell density (ECD) were estimated. RESULTS: Twenty subjects were enrolled (mean age: 73.6±7.3y). The mean medicated preoperative IOP was 16.7 mm Hg in the µLOT and 16.2 mm Hg in the iStent eyes. The mean final IOP at 12mo was 13.6 mm Hg in the µLOT eyes and 13.6 mm Hg in the iStent eyes, representing a 17.8% and 17.2% reduction, respectively. The preoperative ACF in the µLOT eyes was 9.5 pc/ms and it returned to normal in 30d postoperatively, with a value of 11.4 pc/ms. In the iStent eyes, ACF was 9.6 pc/ms preoperatively and it returned to normal by 7d postoperatively (11.2 pc/ms at day 7), demonstrating that postoperative inflammation was less in the iStent eyes. The corneal ECD in both groups was not significantly decreased. CONCLUSION: In this study, iStent and µLOT are both effective through 12mo of follow-up. Safety is more favorable in the iStent eyes, based on early anterior chamber inflammation.

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

Purpose: Netarsudil, a Rho kinase inhibitor with norepinephrine transport inhibitory effect, lowers intraocular pressure, however, its effect on axon damage remains to be elucidated. The aim of the current study was to investigate the effect of netarsudil on TNF-induced axon loss and to examine whether it affects phosphorylated-AMP-activated kinase (p-AMPK) and autophagy in the optic nerve. Methods: Intravitreal administration of TNF or TNF with netarsudil was carried out on rats and quantification of axon number was determined. Electron microscopy determined autophagosome numbers. Localization of p-AMPK expression was examined by immunohistochemistry. The changes in p62, LC3-II, and p-AMPK levels were estimated in the optic nerve by immunoblot analysis. The effect of an AMPK activator A769662 or an AMPK inhibitor dorsomorphin on axon number was evaluated. Results: Morphometric analysis revealed apparent protection by netarsudil against TNF-induced axon degeneration. Netarsudil increased autophagosome numbers inside axons. Netarsudil treatment significantly upregulated optic nerve LC3-II levels in both the TNF-treated eyes and the control eyes. Increased p62 protein level induced by TNF was significantly ameliorated by netarsudil. The netarsudil administration alone lessened p62 levels. Netarsudil significantly upregulated the optic nerve p-AMPK levels. A769662 exhibited obvious axonal protection against TNF-induced damage. A769662 treatment upregulated LC3-II levels and the increment of p62 level induced by TNF was significantly ameliorated by A769662. Immunohistochemical analysis revealed that p-AMPK is present in axons. Netarsudil-mediated axonal protection was significantly suppressed by dorsomorphin administration. Conclusions: Netarsudil upregulated p-AMPK and autophagy. Netarsudil-mediated axonal protection may be associated with upregulated p-AMPK.

Efficacy of Fovea-Sparing Internal Limiting Membrane Peeling for Epiretinal Membrane Foveoschisis.

INTRODUCTION: The aim of the study was to investigate the outcomes of vitrectomy with fovea-sparing internal limiting membrane (ILM) peeling (FSIP) for epiretinal membrane (ERM) foveoschisis based on new optical coherence tomography definitions. METHODS: Twenty-three eyes of 22 patients (69.7 ± 9.9 years old) who underwent vitrectomy with FSIP without gas tamponade for ERM foveoschisis were analyzed. All patients underwent follow-up examinations for at least 12 months. In the FSIP technique, the ILM is peeled off in a donut shape, preserving the foveal ILM. The logarithm of the minimal angle of resolution best-corrected visual acuity (BCVA), central macular thickness (CMT), and surgical complications were examined. RESULTS: The BCVA at 12 months improved significantly from baseline (p < 0.001). Baseline ellipsoid zone defects were found in 2 eyes (9%), and all defective eyes had recovered at 12 months. CMT decreased significantly from baseline (p < 0.001). Acute macular edema, full-thickness macular hole, and recurrence of ERM were not observed during follow-up. DISCUSSION/CONCLUSION: FSIP achieved good visual outcome and retinal morphological change. Moreover, FSIP might avoid acute macular edema in ERM foveoschisis surgery.

Akebia Saponin D prevents axonal loss against TNF-induced optic nerve damage with autophagy modulation.

Akebia Saponin D (ASD), a triterpenoid saponin, was shown to have protective effects in certain neuronal cells. The purpose of the present study was to investigate the possibility of ASD to prevent tumor necrosis factor (TNF)-induced axonal loss and the ASD modulation of the biologic process of autophagy in optic nerves. Rats were given intravitreal administration of TNF, simultaneous administration of 2, 20, or 200 pmol ASD and TNF, or ASD alone. LC3-II and p62 expression, which is a marker of autophagic flux, and phosphorylated p38 (p-p38) expression in optic nerves were examined by immunoblot analysis. Morphometric analysis revealed a significant ameliorated effect of ASD against TNF-induced optic nerve damage. p62 was significantly increased in the optic nerve in TNF-treated eyes, but this increase was totally prevented by ASD. The ASD alone injection showed significant reduction of p62 levels compared with the PBS-treated control eyes. LC3-II was significantly increased by ASD treatment in the TNF-injected eyes. p-p38 was significantly increased in the optic nerve in TNF-treated eyes, but this increase was completely prevented by ASD. The protective effects of ASD may be associated with enhanced autophagy activation and inhibition of p-p38.

Axonal Protection by Nicotinamide Riboside via SIRT1-Autophagy Pathway in TNF-Induced Optic Nerve Degeneration.

Nicotinamide adenine dinucleotide (NAD+) synthesis pathway has been involved in many biological functions. Nicotinamide riboside (NR) is widely used as an NAD+ precursor and known to increase NAD+ level in several tissues. The present study aimed to examine the effect of NR on tumor necrosis factor (TNF)-induced optic nerve degeneration and to investigate whether it alters SIRT1 expression and autophagic status in optic nerve. We also examined the localization of nicotinamide riboside kinase 1 (NRK1), which is a downstream enzyme for NR biosynthesis pathway in retina and optic nerve. Intravitreal injection of TNF or TNF plus NR was performed on rats. The p62 and LC3-II protein levels were examined to evaluate autophagic flux in optic nerve. Immunohistochemical analysis was performed to localize NRK1 expression. Morphometric analysis showed substantial axonal protection by NR against TNF-induced axon loss. TNF-induced increment of p62 protein level was significantly inhibited by NR administration. NR administration alone significantly increased the LC3-II levels and reduced p62 levels compared with the basal levels, and upregulated SIRT1 levels in optic nerve. Immunohistochemical analysis showed that NRK1 exists in retinal ganglion cells (RGCs) and nerve fibers in retina and optic nerve. NR administration apparently upregulated NRK1 levels in the TNF-treated eyes as well as the control eyes. Pre-injection of an SIRT1 inhibitor resulted in a significant increase of p62 levels in the NR plus TNF treatment group, implicating that SIRT1 regulates autophagy status. In conclusion, NRK1 exists in RGCs and optic nerve axons. NR exerted protection against axon loss induced by TNF with possible involvement of upregulated NRK1 and SIRT1-autophagy pathway.

Axonal protection by a small molecule SIRT1 activator, SRT2104, with alteration of autophagy in TNF-induced optic nerve degeneration.

PURPOSE: To examine the effects of SRT2104, an SIRT1 activator, in optic nerve degeneration induced by TNF and to investigate whether it affects the autophagic status after induction of axonal degeneration. STUDY DESIGN: Experimental. METHODS: Adult male Wistar rats received intravitreal injection of TNF alone, concomitant injection of SRT2104 and TNF, or injection of SRT2104 alone. The autophagic status in the optic nerve was evaluated to examine p62 and LC3-II expression by immunoblot analysis. The effect of SRT2104 on TNF-induced axon loss was determined by counting the number of axons. RESULTS: Intravitreal injection of SRT2104 showed a modest protective tendency in the 2-pmol-treated groups against TNF-induced axon loss, although the tendency was not significant on quantitative analysis. However, significant protective effects were found in the 20- or 200-pmol-treated groups. Injection of SRT2104 alone significantly decreased the p62 levels and increased the LC3-II levels as compared with the basal levels. Similarly, concomitant injection of SRT2104 and TNF significantly decreased the p62 levels and increased the LC3-II levels as compared with the TNF-treated group. Upregulation of SIRT1 expression was observed in the optic nerve after SRT2104 treatment. CONCLUSION: The SIRT1 activator SRT2104 exerts axonal protection in TNF-induced optic nerve degeneration. This effect may be associated with upregulated autophagic status in the optic nerve.

Axonal Protection by Tacrolimus with Inhibition of NFATc1 in TNF-Induced Optic Nerve Degeneration.

Tacrolimus, a calcineurin (CaN) inhibitor, has been used for treatment of refractory allergic ocular disease, although its role in optic nerve degeneration remains to be elucidated. In this study, we investigated whether tacrolimus modulates tumor necrosis factor (TNF)-mediated axonal degeneration and whether it alters nuclear factor of activated T cells (NFATc), a downstream effector of CaN signaling. Immunoblot analysis showed no significant difference in CaNAα protein levels in optic nerve on day 3, 7, or 14 after TNF injection compared with PBS injection. However, a significant increase in NFATc1 protein level was observed in optic nerve 7 days after TNF injection. This increase was negated by simultaneous administration of tacrolimus. Administration of tacrolimus alone did not change the NFATc1 protein level in comparison to that observed after PBS injection. A significant increase in TNF protein level was observed in optic nerve 14 days after TNF injection and this increase was prevented by tacrolimus. Immunohistochemical analysis showed the immunoreactivity of NFATc1 to be increased in optic nerve after TNF injection. This increased immunoreactivity was colocalized with glial fibrillary acidic protein and was suppressed by tacrolimus. Treatment of tacrolimus significantly ameliorated the TNF-mediated axonal loss. These results suggest that tacrolimus is neuroprotective against axon loss in TNF-induced optic neuropathy and that the effect arises from suppression of the CaN/NFATc1 pathway.

HEMI-TEMPORAL INTERNAL LIMITING MEMBRANE PEELING IS AS EFFECTIVE AND SAFE AS CONVENTIONAL FULL PEELING FOR MACULAR HOLE SURGERY.

PURPOSE: To investigate the efficacy of hemi-temporal internal limiting membrane (ILM) peeling for idiopathic macular hole. METHODS: The medical records of patients with macular holes who had undergone vitrectomy with ILM peeling were studied. Forty-two eyes with macular hole were divided into 2 groups based on surgical procedure (hemi-temporal ILM peeling [hemi group]: 15 eyes; 360° ILM peeling [360° group]: 27 eyes). The closure rates and distances between the optic disc and the intersection of two retinal vessels most closely located nasally or temporally to the macular hole were compared. RESULTS: The primary closure rates were not significantly different between the two groups (hemi group: 93.3%; 360° group: 92.5%, P = 0.92). The temporal retinal vessels in the hemi group were displaced 120.5 ± 102.0 µm toward the optic disc at 1 week postoperatively, which did not differ significantly from the 360° group (136.1 ± 106.1 µm) (P = 0.107). However, the nasal retinal vessels in the hemi group were displaced by 42.4 ± 42.9 µm at 1 week postoperatively, which was significantly less than the 90.1 ± 77.3 µm displacement seen in the 360° group (P = 0.040). CONCLUSION: Hemi-temporal ILM peeling may be preferable to 360° ILM peeling because of less displacement of the retina and greater safety.

Involvement of Beclin­1 in axonal protection by short­term hyperglycemia against TNF­induced optic nerve damage.

Beclin­1 serves a pivotal role in autophagosome formation. A previous study demonstrated that streptozotocin­induced hyperglycemia (HG) ameliorates axonal loss induced by tumor necrosis factor (TNF) with upregulation of autophagy in rats. The aim of present study was to examine whether Beclin­1 is involved in this autophagy machinery. Immunoblot analysis of optic nerves demonstrated that HG upregulated Beclin­1 protein expression when compared with normoglycemia (NG). Intravitreal administration of TNF did not alter the optic nerve Beclin­1 expression in NG nor in HG. Beclin­1 immunoreactivity was revealed to be mainly in astrocytes in optic nerves; however, it was also observed in the neurofilaments of the HG group. Morphometric analysis revealed that HG appeared to have substantial ameliorative effects on axon loss and this ameliorative effect was partially prevented by Beclin­1 small interfering RNA. These results indicated that Beclin­1 may exist in neurons and glia in optic nerves and increased Beclin­1 expression may be at least partially associated with axonal protection by HG.

Axonal Protection by Ripasudil, a Rho Kinase Inhibitor, via Modulating Autophagy in TNF-Induced Optic Nerve Degeneration.

Purpose: The Rho kinase inhibitor ripasudil decreases intraocular pressure, although its role in optic nerve axonal damage should be clarified. We therefore investigated whether ripasudil modulates TNF-induced axonal loss and affects autophagy machinery after the induction of optic nerve degeneration. Methods: Rats were given intravitreal injection of TNF, concomitant injection of ripasudil hydrochloride hydrate and TNF, or ripasudil alone. Axon numbers were counted to evaluate the effects of ripasudil against axon loss. Immunoblot analysis was performed to examine p62 as well as LC3-II expression in optic nerves. Electron microscopy was used to determine autophagosome numbers in axons and glia. Immunogold labeling was performed to evaluate autophagosomes in axons. Results: Ripasudil injected intravitreally resulted in significant neuroprotection against TNF-induced axon loss. Intravitreal TNF injection upregulated p62 in the optic nerve, but ripasudil completely inhibited this increment. The ripasudil alone injection diminished p62 and enhanced LC3-II protein levels significantly compared with baseline. Ripasudil-induced upregulation of LC3-II was seen after TNF injection, and immunohistochemical analysis revealed that LC3 colocalized in nerve fibers. Electron microscopic analysis revealed that autophagosomes were present in axons and glia, although autophagosome numbers increased significantly after ripasudil injection only in axons. Conclusions: These results suggest that ripasudil-enhanced intra-axonal autophagy is at least partly involved in axonal protection.

Foveal Microstructure Analysis in Eyes with Diabetic Macular Edema Treated with Vitrectomy.

INTRODUCTION: The purpose of this study was to evaluate baseline and postoperative factors affecting outcomes after vitrectomy for diabetic macular edema (DME) using optical coherence tomography (OCT). METHODS: Vitrectomy combined with inner limiting membrane (ILM) peeling and additional laser photocoagulation therapy was performed on 36 eyes of 30 DME patients. Evaluations included the logarithm of the minimal angle of resolution (logMAR), best-corrected visual acuity (BCVA) and OCT parameters at baseline and 1, 3, 6, and 12 months postoperatively. Correlations between OCT parameters and BCVA were assessed at each follow-up visit. Correlations among postoperative BCVA and preoperative BCVA, foveal macular thickness (FMT), outer foveal thickness (OFT), and photoreceptor outer segment (PROS) length were evaluated using multiple regression analysis. RESULTS: BCVA significantly improved from 0.50 ± 0.25 to 0.34 ± 0.26 at 12 months postoperatively (P < 0.001). Mean FMT improved significantly from 526.4 ± 120.4 to 384.6 ± 120.5 at 1 month, 325.2 ± 100.3 at 3 months, 304.1 ± 102.5 at 6 months and 274.2 ± 86.6 µm at 12 months postoperatively (P < 0.001, respectively). OFT 1 month after surgery was significantly decreased 46.5 ± 14.7-40.2 ± 14.4 µm (P = 0.017), although at 3, 6, and 12 months it did not differ from the baseline value. PROS length 1 month after surgery significantly decreased from 31.7 ± 6.9-28.8 ± 6.8 µm (P = 0.015) and that at 3 months and 6 months recovered to the baseline value. PROS length 12 months after surgery was significantly increased to 34.3 ± 7.2 µm from baseline (P = 0.023). Mean FMT was not correlated with BCVA at any time point. Mean OFT and PROS length at 3, 6, and 12 months were correlated with BCVA. In multiple regression analysis, PROS length had the greatest effect on VA 12 months postoperatively (P = 0.0262, standard regression coefficient = -0.366). CONCLUSION: Current surgery helps DME patients to maintain VA and foveal structures. The results suggest that PROS length predicts visual outcome in DME patients following vitrectomy with ILM peeling and additional laser photocoagulation.

Axonal protection by thioredoxin-1 with inhibition of interleukin-1ß in TNF-induced optic nerve degeneration.

Interleukin (IL)-1ß, a proinflammatory cytokine, is a key mediator in several acute and chronic neurological diseases. Thioredoxin-1 (TRX1) acts as an antioxidant and plays a protective role in certain neurons. We examined whether exogenous TRX1 exerts axonal protection and affects IL-1ß levels in tumor necrosis factor (TNF)-induced optic nerve degeneration in rats. Immunoblot analysis showed that IL-1ß was upregulated in the optic nerve after intravitreal injection of TNF. Treatment with recombinant human (rh) TRX1 exerted substantial protective effects against TNF-induced axonal loss. The increase in the IL-1ß level in the optic nerve was abolished by rhTRX1. Treatment with rhTRX1 also significantly inhibited increased glial fibrillary acidic protein (GFAP) levels induced by TNF. Immunohistochemical analysis showed substantial colocalization of IL-1ß and GFAP in the optic nerve after TNF injection. These results suggest that IL-1ß is upregulated in astrocytes in the optic nerve after TNF injection and that exogenous rhTRX1 exerts axonal protection with an inhibitory effect on IL-1ß.

Axonal protection by short-term hyperglycemia with involvement of autophagy in TNF-induced optic nerve degeneration.

Previous reports showed that short-term hyperglycemia protects optic nerve axons in a rat experimental hypertensive glaucoma model. In this study, we investigated whether short-term hyperglycemia prevents tumor necrosis factor (TNF)-induced optic nerve degeneration in rats and examined the role of autophagy in this axon change process. In phosphate-buffered saline (PBS)-treated rat eyes, no significant difference in axon number between the normoglycemic (NG) and streptozotocin (STZ)-induced hyperglycemic (HG) groups was seen at 2 weeks. Substantial degenerative changes in the axons were noted 2 weeks after intravitreal injection of TNF in the NG group. However, the HG group showed significant protective effects on axons against TNF-induced optic nerve degeneration compared with the NG group. This protective effect was significantly inhibited by 3-methyladenine (3-MA), an autophagy inhibitor. Immunoblot analysis showed that the LC3-II level in the optic nerve was increased in the HG group compared with the NG group. Increased p62 protein levels in the optic nerve after TNF injection was observed in the NG group, and this increase was inhibited in the HG group. Electron microscopy showed that autophagosomes were increased in optic nerve axons in the HG group. Immunohistochemical study showed that LC3 was colocalized with nerve fibers in the retina and optic nerve in both the NG and HG groups. Short-term hyperglycemia protects axons against TNF-induced optic nerve degeneration. This axonal-protective effect may be associated with autophagy machinery.

Axonal protection by brimonidine with modulation of p62 expression in TNF-induced optic nerve degeneration.

PURPOSE: The p62, also called sequestosome 1 (SQSTM1), plays a crucial role in tumor necrosis factor (TNF)-induced optic nerve degeneration. Brimonidine has been shown to have protective effects on retinal ganglion cell bodies, although its role in their axons remains to be examined. We determined whether brimonidine modulates axonal loss induced by TNF and affects the expression of p62 in the optic nerve. METHODS: Experiments were performed on adult male Wistar rats that received an intravitreal injection of 10 ng TNF alone or simultaneous injection of TNF and 2, 20, or 200 pmol of brimonidine tartrate. The expression of p62 in the optic nerve was examined by immunoblot analysis. The effects of brimonidine on axons were evaluated by counting axon numbers 2 weeks after intravitreal injection. RESULTS: Intravitreal injection of brimonidine exerted substantial axonal protection against TNF-induced optic nerve degeneration. Immunoblot analysis showed that p62 was upregulated in the optic nerve after intravitreal injection of TNF, and that this increase was completely inhibited by brimonidine. Treatment with brimonidine alone also significantly decreased p62 protein levels in the optic nerve compared with the basal level. CONCLUSIONS: These results suggest that the modulation of p62 levels in the optic nerve by brimonidine may be involved partly in its axonal protection.

Autophagy in axonal degeneration in glaucomatous optic neuropathy.

The role of autophagy in retinal ganglion cell (RGC) death is still controversial. Several studies focused on RGC body death, although the axonal degeneration pathway in the optic nerve has not been well documented in spite of evidence that the mechanisms of degeneration of neuronal cell bodies and their axons differ. Axonal degeneration of RGCs is a hallmark of glaucoma, and a pattern of localized retinal nerve fiber layer defects in glaucoma patients indicates that axonal degeneration may precede RGC body death in this condition. As models of preceding axonal degeneration, both the tumor necrosis factor (TNF) injection model and hypertensive glaucoma model may be useful in understanding the mechanism of axonal degeneration of RGCs, and the concept of axonal protection can be an attractive approach to the prevention of neurodegenerative optic nerve disease. Since mitochondria play crucial roles in glaucomatous optic neuropathy and can themselves serve as a part of the autophagosome, it seems that mitochondrial function may alter autophagy machinery. Like other neurodegenerative diseases, optic nerve degeneration may exhibit autophagic flux impairment resulting from elevated intraocular pressure, TNF, traumatic injury, ischemia, oxidative stress, and aging. As a model of aging, we used senescence-accelerated mice to provide new insights. In this review, we attempt to describe the relationship between autophagy and recently reported noteworthy factors including Nmnat, ROCK, and SIRT1 in the degeneration of RGCs and their axons and propose possible mechanisms of axonal protection via modulation of autophagy machinery.

Axonal protection by modulation of p62 expression in TNF-induced optic nerve degeneration.

p62, which is also called sequestosome 1 (SQSTM1), plays a critical role in neuronal cell death. However, the role of p62 in axonal degeneration remains unclear. We evaluated whether the modulation of p62 expression may affect axonal loss in tumor necrosis factor (TNF)-induced optic nerve degeneration. Immunoblot analysis showed that p62 was upregulated in the optic nerve after intravitreal injection of TNF. Treatment with p62 small interfering RNA (siRNA) exerted a partial but significant protective effect against TNF-induced axonal loss. Rapamycin exerted substantial axonal protection after TNF injection. We found that the increase in p62 was significantly inhibited by p62 siRNA. Treatment with rapamycin also significantly inhibited increased p62 protein levels induced by TNF. These results suggest that the upregulation of p62 may be involved in TNF-induced axonal degeneration and that decreased p62 levels may lead to axonal protection.

[Tumor necrosis factor-induced optic nerve degeneration and axonal protection].

The molecular mechanism of axonal degeneration in the optic nerve remains unclear. The optic nerve contains axons and glia such as oligodendrocytes, astrocytes, as well as microglia. Tumor necrosis factor (TNF) has been implicated in the pathogenesis of glaucomatous optic neuropathy (GON). A TNF-induced optic nerve degeneration model demonstrated primary axonal degeneration and subsequent retrograde loss of retinal ganglion cell bodies. In this review, we address the molecular mechanism of axonal degeneration from the viewpoint of the axons and surrounding glial cells. Brain-derived neurotrophic factor and the amyloidogenic pathway may play important roles in glial events, while nicotinamide mononucleotide adenylyltransferase 1 and thioredoxin 1 may play important roles within axons. Understanding the molecular mechanisms of axonal degeneration in the optic nerve will open a new avenue for treatment of GON by introducing the novel concept of "axoprotectant ".

Axonal protection via modulation of the amyloidogenic pathway in tumor necrosis factor-induced optic neuropathy.

PURPOSE: To examine the changes in and localization of phosphorylated presenilin1 (p-PS1) and amyloid precursor protein (APP) in the optic nerve after intravitreal injection of TNF and to investigate the role of γ-secretase in the cleavage of APP in optic nerve degeneration. METHODS: Groups of rats were euthanatized at 1 or 2 weeks after intravitreal injection of TNF. Levels of p-PS1 protein in the optic nerve were determined by immunoblotting and immunohistochemistry. The localization of APP was determined by immunohistochemistry, and its downstream cleavage was determined by immunoprecipitation using 6E10 antibody followed by immunoblotting with an APP intracellular domain (AICD) antibody. The effect of a γ-secretase inhibitor on TNF-induced optic nerve degeneration was determined by counting the number of axons. RESULTS: p-PS1 was increased in the optic nerve after TNF injection and was found to colocalize with vimentin and glial fibrillary acidic protein, markers of astrocytes. Immunoprecipitation using 6E10 antibody followed by immunoblotting with AICD antibody revealed an increase in γ-secretase activation in the optic nerve after TNF injection, which was inhibited by treatment with the γ-secretase inhibitor. Moreover, γ-secretase inhibition significantly prevented the loss of axons in the optic nerve after TNF injection. CONCLUSIONS: The increase in p-PS1 and activation of γ-secretase in the optic nerve may be associated with TNF-induced axonal degeneration. Modulation of γ-secretase activity may be useful for the treatment of TNF-related optic neuropathy.

[Effects of selective laser trabeculoplasty treatment in steroid-induced glaucoma].

PURPOSE: To evaluate the effectiveness of selective laser trabeculoplasty (SLT) on steroid-induced glaucoma. METHODS: The study included 46 eyes of 41 subjects who were followed up for at least 12 months after SLT. The included 10 eyes with steroid-induced glaucoma, 16 eyes with primary open angle glaucoma (POAG), 10 eyes with pseudoexfoliation glaucoma (PEX.G) and 10 eyes with mixed glaucoma (Mixed. G). The range of the SLT laser was 360 degrees. Intraocular pressure (IOP) before and after SLT, and cumulative survival rate after SLT were determined. RESULTS: Significant decreases in IOP were observed after SLT in the steroid-induced glaucoma group, the POAG group and the PEX.G group. At 12 months after SLT, preoperation IOP decreased by 35.9% (29.9 +/- 7.5 mmHg to 17.9 +/- 2.2 mmHg) in the steroid-induced glaucoma group, 13.2% (20.0 +/- 3.0 mmHg to 17.3 +/- 3.1 mmHg) in the POAG group, 10.7% (21.1 +/- 4.0 mmHg to 18.1 +/- 4.1 mmHg) in the PEX.G group and 6.9% (21.3 +/- 1.9 mmHg to 19.9 +/- 3.4 mmHg) in the Mixed.G group. Cumulative survival rates were 80%, 56.3%, 50.0%, 40.0% in the steroid-induced glaucoma, POAG, PEX.G, and Mixed. G groups, respectively, at 12 months after SLT (Logrank test, p = 0.467). CONCLUSION: These data suggest that SLT increased IOP reduction rates for steroid-induced glaucoma more than for any other group.