Oxidative stress and mitochondrial failure in the pathogenesis of glaucoma neurodegeneration

Biomarkers of lipid peroxidation in the aqueous humor of primary open-angle glaucoma patients

OBJECTIVE

To investigate the lipid peroxidation (PEROX) processes in primary open-angle glaucoma (POAG) patients, and whether this mechanism may be related to disease progression.

MATERIAL AND METHODS

A prospective, observational, cross-sectional, non-experimental, and analytical study was conducted on a case and a comparison group, consisting of 175 surgical patients divided into: 1) POAG group (GG; n=88) and 2) comparison group of patients with cataracts (CG; n=87). Demographic data, patient characteristics, lifestyle data, as well as ophthalmological examination were registered in an Excel spreadsheet. Biochemical data were obtained by processing the aqueous humor collected at the beginning of surgery. Determination of malondialdehyde/thiobarbituric acid reactive substances (MDA/TBARS) and total antioxidant activity (AAO) was assayed using enzymatic-colorimetric methods in the aqueous humor samples. Statistical analysis was performed using SPSS 15.0 software.

RESULTS

Aqueous humor MDA/TBARS levels were significantly higher (P<.001) and the AAO significantly lower (P<.001) in the GG than in the GC. The MDA/TBARS directly correlated with intraocular pressure (IOP) values and the cup-to-disc ratio (CDR). Decreased AAO activity correlated inversely with IOP and CDR. Differences between groups were noticeably higher in the GG as regards obesity, alcohol consumption, anxiety, depression, and sedentary lifestyle. In the multivariate analysis, the variables that showed a better predictive ability were: MDA/TBARS, PIO, AAO, CDR, and depression.

CONCLUSIONS

The POAG patients have a PEROX background that is reflected in the aqueous humor by variations in MDA/TBARS and AAO. Moreover, both the MDA/TBARS and AAO correlated with IOP values and the CDR. We propose that determination of MDA/TBARS and AAO in the aqueous humor of POAG patients can be used as biomarkers for monitoring the disease, as well the changes in lifestyle and other related risk factors.

Virus-mediated EpoR76E gene therapy preserves vision in a glaucoma model by modulating neuroinflammation and decreasing oxidative stress

BACKGROUND

Glaucoma is a complex neurodegeneration and a leading cause of blindness worldwide. Current therapeutic strategies, which are all directed towards lowering the intraocular pressure (IOP), do not stop progression of the disease. We have demonstrated that recombinant adeno-associated virus (rAAV) gene delivery of a form of erythropoietin with attenuated erythropoietic activity (EpoR76E) can preserve retinal ganglion cells, their axons, and vision without decreasing IOP. The goal of this study was to determine if modulation of neuroinflammation or oxidative stress played a role in the neuroprotective activity of EPO.R76E.

METHODS

Five-month-old DBA/2J mice were treated with either rAAV.EpoR76E or a control vector and collected at 8 months of age. Neuroprotection was assessed by quantification of axon transport and visual evoked potentials. Microglia number and morphology and cytokine and chemokine levels were quantified. Message levels of oxidative stress-related proteins were assessed.

RESULTS

Axon transport and visual evoked potentials were preserved in rAAV.EpoR76E-treated mice. The number of microglia was decreased in retinas from 8-month-old rAAV.EpoR76E-treated mice, but proliferation was unaffected. The blood-retina barrier was also unaffected by treatment. Levels of some pro-inflammatory cytokines were decreased in retinas from rAAV.EpoR76E-treated mice including IL-1, IL-12, IL-13, IL-17, CCL4, and CCL5. TNFα messenger RNA (mRNA) was increased in retinas from 8-month-old mice compared to 3-month-old controls regardless of treatment. Expression of several antioxidant proteins was increased in retinas of rAAV.EpoR76E-treated 8-month-old mice.

CONCLUSIONS

Treatment with rAAV.EpoR76E preserves vision in the DBA/2J model of glaucoma at least in part by decreasing infiltration of peripheral immune cells, modulating microglial reactivity, and decreasing oxidative stress.

An evaluation of ocular elasticity using real-time ultrasound elastography in primary open-angle glaucoma

OBJECTIVE

The aim of this study was to compare sonoelastographic findings in the retina-choroid-sclera (RCS) complex and vitreous in glaucomatous and healthy eyes.

METHODS

For this cross-sectional comparative study, 20 patients with primary open-angle glaucoma and 20 healthy volunteers were recruited. Ultrasound elastography measurements were taken with a sonographic scanner of the RCS complex, anterior vitreous (AV), posterior vitreous (PV), retrobulbar fat tissue (RFT), optic disc (OD) and optic nerve (ON) in each eye.

RESULTS

The elasticity index of the RCS complex, RFT, OD, ON, AV and PV was similar in both groups (p  >  0.05), although the AV/PV strain ratio in the group of patients with glaucoma was significantly higher (p  =  0.04).

CONCLUSION

Glaucoma increases the AV/PV strain ratio. In providing reproducible and consistent values, the real-time elastography (RTE) technique may be helpful in elucidating the mechanisms of glaucoma in some aspects.

ADVANCES IN KNOWLEDGE

This study can help to evaluate the elasticity of the RCS complex and vitreous in glaucomatous eyes with RTE.