Rationale for the use of multifunctional drugs as neuroprotective agents for glaucoma

[Features of neuropsychological status and results of magnetic resonance morphometry in patients with Alzheimer's disease and glaucoma]

OBJECTIVE

To identify the relationship of neuropsychological changes in patients with Alzheimer's disease (AD) and primary open-angle glaucoma (POAG) and to evaluate the results of magnetic resonance (MR)-morphometry in patients with these diseases.

MATERIAL AND METHODS

We examined 32 patients (median age 67 [61.25; 76.75] years, 78.1% women) diagnosed with AD and POAG. The patients were divided into the AD group (n=16) and the POAG group (n=16). Complaints and anamnesis were collected for all patients, neurological status and neuropsychological status were assessed. MRI of the brain, followed by morphometry, was performed.

RESULTS

Cognitive impairments (CI) were revealed in patients of both groups. The severity of CI in patients with AD was more pronounced than in patients with POAG (p<0.001). Alzheimer's type of CI was detected in both groups. MR-morphometry revealed a decrease in the volume of the left hippocampus, the volume of the right and left amygdala as well as a decrease in the thickness of the right and left entorhinal cortex in the AD group compared with the POAG group (p<0.05). A significant decrease in the thickness of the right medial orbitofrontal cortex was found in the POAG group compared with the AD group (p<0.05).

CONCLUSION

In AD and POAG, there is a similarity of the neuropsychological profile, which reflects the neurodegeneration characteristic of these diseases. MRI morphometry requires an assessment of both volumes and thickness of brain structures. A neuroimaging pattern identified in patients with POAG can be regarded as an indicator of the glaucomatous process.

17β-Estradiol Delivered in Eye Drops: Evidence of Impact on Protein Networks and Associated Biological Processes in the Rat Retina through Quantitative Proteomics

To facilitate the development of broad-spectrum retina neuroprotectants that can be delivered through topical dosage forms, this proteomics study focused on analyzing target engagements through the identification of functional protein networks impacted after delivery of 17β-estradiol in eye drops. Specifically, the retinae of ovariectomized Brown Norway rats treated with daily eye drops of 17β-estradiol for three weeks were compared to those of vehicle-treated ovariectomized control animals. We searched the acquired raw data against a composite protein sequence database by using Mascot, as well as employed label-free quantification to detect changes in protein abundances. Our investigation using rigorous validation criteria revealed 331 estrogen-regulated proteins in the rat retina (158 were up-regulated, while 173 were down-regulated by 17β-estradiol delivered in eye drops). Comprehensive pathway analyses indicate that these proteins are relevant overall to nervous system development and function, tissue development, organ development, as well as visual system development and function. We also present 18 protein networks with associated canonical pathways showing the effects of treatments for the detailed analyses of target engagements regarding potential application of estrogens as topically delivered broad-spectrum retina neuroprotectants. Profound impact on crystallins is discussed as one of the plausible neuroprotective mechanisms.

17β-estradiol eye drops protect the retinal ganglion cell layer and preserve visual function in an in vivo model of glaucoma

Neuroprotection in glaucoma as a curative strategy complementary to current therapies to lower intraocular pressure (IOP) is highly desirable. This study was designed to investigate neuroprotection by 17β-estradiol (E2) to prevent retinal ganglion cell (RGC) death in a glaucoma model of surgically elevated IOP in rats. We found that daily treatment with E2-containing eye drops resulted in significant E2 concentration in the retina with concomitant profound neuroprotective therapeutic benefits, even in the presence of continually elevated IOP. The number of apoptotic cells in the RGC layer was significantly decreased in the E2-treated group, when compared to the vehicle-treated controls. Deterioration in visual acuity in these animals was also markedly prevented. Using mass spectrometry-based proteomics, beneficial changes in the expression of several proteins implicated in the maintenance of retinal health were also found in the retina of E2-treated animals. On the other hand, systemic side effects could not be avoided with the eye drops, as confirmed by the measured high circulating estrogen levels and through the assessment of the uterus representing a typical hormone-sensitive peripheral organ. Collectively, the demonstrated significant neuroprotective effect of topical E2 in the selected animal model of glaucoma provides a clear rationale for further studies aiming at targeting E2 into the eye while avoiding systemic E2 exposure to diminish undesirable off-target side effects.