Alzheimer's peptide and serine proteinase inhibitors in glaucoma and exfoliation syndrome

Comparative Proteomic Analysis of the Aqueous Humor from Patients with Pseudoexfoliation Syndrome

Purpose

The goal of this study was to pinpoint potential molecular pathways that may have contributed to the onset of pseudoexfoliation syndrome (PEX), a systemic illness associated with aging that has no known cause and is brought on by the deposition of fibrillary white flaky debris in ocular tissues.

Materials and methods

Protein pools representing each group were created using two-dimensional gel electrophoresis (2DE) in conjunction with a matrix-assisted laser desorption ionization-time of flight/time of flight (MALDI-TOF/TOF) mass spectrometer. Aqueous humor (AH) from patients with PEX and cataracts was also collected for a comprehensive study of the data; ingenuity pathway analysis (IPA) was used for the discovered proteins.

Results

In comparison to controls, 2DE showed that 10 sites in PEX patients had differently altered gene expression. Two of these proteins, transthyretin (TTR) and apolipoprotein A4 (ApoA4) were significantly overexpressed in PEX patients, but the remaining proteins were only mildly altered. The liver X receptor (LXR) and the retinoid X receptors (RXR) may play a crucial role in the pathophysiology of PEX according to IPA employing these 10 proteins.

Conclusion

The altered proteins, particularly ApoA4 and TTR, may be important in revealing the molecular process behind PEX, as anticipated by IPA.

How to cite this article

Toprak M, Yuksel N, Akpinar G, et al. Comparative Proteomic Analysis of the Aqueous Humor from Patients with Pseudoexfoliation Syndrome. J Curr Glaucoma Pract 2023;17(3):118-125.

Association between pseudoexfoliation and Alzheimer's disease-related brain atrophy

BACKGROUND/AIMS

Pseudoexfoliation (PEX) syndrome is an age-related disorder characterized by the accumulation of extracellular material in the anterior eye segment. PEX pathogenesis is not fully understood, but amyloid which accumulates in the brain of patients with Alzheimer's disease (AD) is a PEX component. PEX deposition shares features with amyloid aggregation in AD, and brain atrophy is a common AD feature, with β-amyloid accumulation among contributing factors. This study investigated whether PEX syndrome is associated with AD-related brain atrophy.

METHODS

We reviewed the medical records of patients diagnosed with PEX at the Veterans Health Service Medical Center between January 2015 and August 2021. This retrospective cohort study included 48 patients with PEX and 48 healthy age- and sex-matched controls. Patients with PEX were divided into two groups: with and without glaucoma. The main outcome measure was brain atrophy, using a visual rating scale, and AD incidence. Brain atrophy was measured using the Scheltens scale for medial temporal atrophy, the posterior cortical atrophy scale for parietal atrophy, and the Pasquier scale for global cortical atrophy.

RESULTS

The percentage of participants with medial temporal atrophy was 56.3% in the PEX group and 35.4% in the control group. The global cortical atrophy and parietal atrophy scores were significantly higher in the PEX group (P<0.05), whereas the PEX and PEX glaucoma groups showed no difference. Among the 96 participants, 16 and 5 participants in the PEX and control groups, respectively, were diagnosed with dementia. Patients with PEX glaucoma tended to have lower Mini-Mental State Examination scores, indicating impaired cognitive function, than those without glaucoma.

CONCLUSION

PEX is associated with brain atrophy, reflecting the risk of developing AD. Patients with PEX glaucoma may present with advanced AD stages. Our results suggest that PEX may be a predictor of AD.

Ocular biomarkers and their role in the early diagnosis of neurocognitive disorders

Given the fact that different types of dementia can be diagnosed only postmortem or when the disease has progressed enough to cause irreversible damage to certain brain areas, there has been an increasing need for the development of sensitive and reliable methods that can detect early preclinical forms of dementia, before the symptoms have even appeared. Ideally, such a method would have the following characteristics: to be inexpensive, sensitive and specific, Non-invasive, fast and easily accessible. The ophthalmologic examination and especially the study of the retina, has caught the attention of many researchers, as it can provide a lot of information about the CNS and it fulfills many of the aforementioned criteria. Since the introduction of the non-invasive optical coherence tomography (OCT) and the newly developed modality OCT-angiography (OCT-A) that can demonstrate the structure and the microvasculature of the retina and choroid, respectively, there have been promising results regarding the value of the ophthalmologic examination in the early diagnosis of Alzheimer's disease. In this review paper, we summarize and discuss the ocular findings in patients with cognitive impairment disorders and we highlight the importance of the ophthalmologic examination to the diagnosis of these disorders.

Evaluating the Correlation between Alzheimer's Amyloid-β Peptides and Glaucoma in Human Aqueous Humor

Purpose

Recent studies suggest that glaucoma may share common pathogenic mechanisms with Alzheimer's disease. To test this hypothesis, we investigated the correlation between glaucoma and amyloid-β₄₂ (Aβ₄₂) concentration in human samples of aqueous humor (AH).

Methods

Eighty-one candidates for cataract or glaucoma surgery were consecutively enrolled, with a median age of 77 years; of these, 32 subjects were affected by glaucoma and 49 were controls. Before surgery, each patient received an ophthalmological examination including biometry, intraocular pressure (IOP) measurement, fundus photography, and determination of the mean thickness of the ganglion cell complex (GCC) and/or retinal nerve fiber layer. During the surgical procedure, an AH sample was collected and immediately processed for total protein (TP) and Aβ₄₂ evaluation.

Results

Aβ₄₂ levels were not statistically different between the glaucomatous and control samples, but a significant increase in TP concentration was found in the AH of glaucoma patients compared with controls (P = 0.02). In addition, positive correlations were observed between TP and Aβ₄₂ (r = 0.51; P < 0.0001), between TP and IOP (r = 0.44; P < 0.0001), and between Aβ₄₂ and IOP (r = 0.22; P = 0.033).

Conclusions

Our results indicate that an increased protein concentration in the AH could play a role in the pathogenesis of glaucomatous disease.

Translational Relevance

This study strongly supports the hypothesis that increased TP in the AH may have a pathogenic role in glaucoma. Further investigations are needed to clarify whether the protein enhancement represents a causative factor and whether it can be used as a marker of disease or as a novel therapeutic target.

Interplay between Oxidative Stress, Inflammation, and Amyloidosis in the Anterior Segment of the Eye; Its Pathological Implications

There are different pathologies associated with amyloidogenic processes caused by the increase of reactive oxygen species (ROS) and the overactivation of inflammatory responses. These alterations are present in different regions of the anterior segment of the eye, and they have been associated with the development and progression of ocular pathologies, such as glaucoma, dry eye syndrome, keratitis, and cataracts among other pathologies. Aim. To discuss briefly the anatomical characteristics of the anterior segment of the eye and describe the interaction between oxidative stress (OS) and inflammatory responses, emphasizing the misfolding of several proteins leading to amyloidogenic processes occurring in the anterior segment and their implications in the development of ocular diseases. We performed a search on PubMed, CINAHL, and Embase using the MeSH terms “eye,” “anterior segment”, “inflammation”, “oxidative stress”, and “amyloidosis”. The search encompassed manuscripts published up to April 2019. A hundred forty-four published studies met the inclusion criteria. We present the current knowledge regarding the interaction between OS and the activation of inflammatory processes and how both can cause conformational changes in several peptides and proteins in each compartment of the anterior segment. However, we found that there is no consensus about which factor is the first to cause amyloidosis. Our conclusions suggest that there is an interplay among these factors forming a vicious cycle that leads to the loss of protein structure in ocular pathologies, and multifactorial therapies should be developed to avoid protein misfolding and to stop the progression of ocular pathologies.

Neurodegeneration in Alzheimer's disease and glaucoma: overlaps and missing links

The eye is said to be the window into the brain. Alzheimer’s disease (AD) and glaucoma both being diseases of the elderly, have several epidemiological and histological overlaps in pathogenesis. Both these diseases are neurodegenerative conditions. Over the years, a consensus has developed that both may be two ends of a singular spectrum of diseases. Epidemiological studies have shown that more Alzheimer’s patients may be suffering from glaucoma than general healthy population. Retinal ganglion cell damage is a characteristic of both diseases, along with discovery of amyloid-β and tau protein deposition in the retina and aqueous humor of eye. The latter two proteins are known to be pathognomonic of AD. Other pathways such as the insulin receptor pathway also seem to be affected in both diseases similarly. In spite of these overlaps, there are few missing links which still need more evidence, namely, intraocular pressure mechanisms, cerebrospinal fluid pressure and trans-lamina cribrosa pressure gradients, vascular autoregulation factors, etc. Several factors point towards a common pathogenesis at some level for both diseases and prospective studies are necessary to study the natural course of both diseases.

Pseudoexfoliation Syndrome and Antidepressant Drug Use

Objectives:

To investigate the relationship between pseudoexfoliation syndrome (PES) and the use of antidepressant medications.

Materials and Methods:

This population-based, cross-sectional study included 2,017 of 2,356 invited subjects who were randomly selected from the Turkish Statistical Institute database (www.turksat.gov.tr/) as part of an epidemiologic study which specifically aimed to detect the prevalence of PES in the province of Eskişehir. During the examination, a detailed questionnaire was administered to determine physician-diagnosed systemic disease and drug use.

Results:

Eight of the 2,017 participants in the study were excluded for various reasons (2 with posterior synechiae, 2 with corneal opacity, 1 uncooperative patient, 1 eviscerated patient, 1 with active adenoviral keratoconjunctivitis, and 1 with a history of angle closure). PES was detected in 100 (5%) of the 2,009 patients whose data were analyzed. The percentage of subjects with concurrent antidepressant drug use in the PES and non-PES non-glaucoma groups were 4.1% (n=3) and 1.1% (n=21), respectively. The difference between the two groups was statistically significant (p=0.024). In addition, the use of medications for hypertension (p<0.001) and coronary artery disease (p=0.009) was also higher in the PES group.

Conclusion:

The higher prevalence of antidepressant drug use in patients with PES may be related to the processes of vascular damage and inflammation common to the pathogenesis of both PES and depression, as well as the high rate of chronic systemic comorbidities in these patients.

Ocular Biomarkers of Alzheimer's Disease: The Role of Anterior Eye and Potential Future Directions

Globally, Alzheimer's disease (AD) is a growing health and economic challenge that has no effective cure. Recent clinical trials indicate that preclinical treatment may be required but a routine screening tool for AD has been elusive. Hence, a simple, yet sensitive biomarker for preclinical AD, when the disease is most likely to be amenable to treatment, is lacking. Due to several features, the eye has been explored for this purpose and, among the ocular tissues, the retina has received the most attention. Currently, major works investigating the potential AD diagnosis by detecting amyloid-β (Aβ) signatures in the retinal tissue are underway, while the anterior eye is more accessible for in vivo imaging and examination. This report provides a concise review of current literature on the anterior eye components, including the crystalline lens, cornea, and aqueous humor, in AD. We also discuss the potential for assessment of the corneal nerve structure and regeneration as well as conjunctival tissue for AD-related alterations. The crystalline lens has received considerable attention, but further research is required to confirm whether Aβ accumulates in the lens and whether it mirrors brain neuropathologic changes, particularly in preclinical AD. The rich corneal neural network and conjunctival vasculature also merit exploration in future studies to shed light on their potential association with AD pathologic changes.

Transient expression of Wnt5a elicits ocular features of pseudoexfoliation syndrome in mice

PURPOSE

Pseudoexfoliation (PEX) syndrome is an age-related systemic disease with ocular manifestations. The development of animal models is critical in order to elucidate the cause of the disease and to test potential treatment regimens. The purpose of this study is to report phenotypes found in mouse eyes injected with Adenovirus coding Wnt5a. Some of the phenotypes resemble those found in PEX patients while others are different.

METHODS

Recombinant Adenovirus coding Wnt5a or green fluorescent protein (GFP) were injected into mouse eyes. Two months after the injection, eyes were examined for PEX phenotypes using slit lamp, fluorescence stereomicroscope, histological staining, immunostaining and transmission electron microscope.

RESULT

Certain ocular features of PEX syndrome were found in mouse eyes injected with recombinant Adenovirus coding Wnt5a. These features include accumulation of exfoliation-like extracellular material on surfaces of anterior segment structures and its dispersion in the anterior chamber, saw-tooth appearance and disrupted basement membrane of the posterior iris pigment epithelium, iris stromal atrophy and disorganized ciliary zonules. Ultrastructure analysis of the exfoliation material revealed that the microfibril structure found in this model was different from those of PEX patients.

CONCLUSION

These features, resembling signs of ocular PEX syndrome in patients, suggest that new information obtained from this study will be helpful for developing better mouse models for PEX syndrome.

The clinical features in patients with newly diagnosed pseudoexfoliative glaucoma in Serbia

PURPOSE

To evaluate the clinical characteristics of newly diagnosed pseudoexfoliative glaucoma and compare them with those pertaining to newly diagnosed primary open-angle glaucoma as well as pseudoexfoliation syndrome.

METHODS

This case-control study involved 306 participants, including patients with newly diagnosed pseudoexfoliative glaucoma, age- and sex-matched normal controls, patients with newly diagnosed primary open-angle glaucoma, and subjects with pseudoexfoliation syndrome. The study was conducted at the Glaucoma Department of Clinic for Eye Diseases, Clinical Center of Serbia, as the referral center for glaucoma in Serbia.

RESULTS

The mean age in the pseudoexfoliative glaucoma, primary open-angle glaucoma, pseudoexfoliation syndrome, and normal control groups was 73.61 ± 8.46, 65.50 ± 8.97, 74.81 ± 6.80, and 73.58 ± 9.34 years, respectively (pseudoexfoliative glaucoma vs primary open-angle glaucoma, p < 0.001). Unilateral pseudoexfoliative glaucoma was diagnosed in 35 patients (42.2%). The intraocular pressure was higher in the eyes affected by pseudoexfoliative glaucoma (32.0 ± 9.5 mmHg) than that in the primary open-angle glaucoma eyes (28.8 ± 5.9 mmHg) (p < 0.001). In pseudoexfoliative glaucoma and primary open-angle glaucoma eyes, glaucoma severity was determined via the vertical cup-to-disk ratio (C/D) 0.65 (0.45-1.0) versus 0.60 (0.45-1.0), p = 0.048 and visual field mean deviation -5.68 (-1.58 to -30.9) versus -4.70 (-1.39 to -31.0), p = 0.045. Alzheimer's was the only systemic disease associated with pseudoexfoliative glaucoma in the study sample, with an odds ratio of 0.021 (95% confidence interval = 0.00-21.52, p = 0.022).

CONCLUSION

At the time of diagnosis, pseudoexfoliative glaucoma exhibits different clinical features compared with primary open-angle glaucoma. Higher intraocular pressure, narrow or occludable angle, increased trabecular pigmentation, phacodonesis, and poorer pupillary dilatation emerged as the factors associated with pseudoexfoliative glaucoma.

Glaucoma related Proteomic Alterations in Human Retina Samples

Glaucoma related proteomic changes have been documented in cell and animal models. However, proteomic studies investigating on human retina samples are still rare. In the present work, retina samples of glaucoma and non-glaucoma control donors have been examined by a state-of-the-art mass spectrometry (MS) workflow to uncover glaucoma related proteomic changes. More than 600 proteins could be identified with high confidence (FDR < 1%) in human retina samples. Distinct proteomic changes have been observed in 10% of proteins encircling mitochondrial and nucleus species. Numerous proteins showed a significant glaucoma related level change (p < 0.05) or distinct tendency of alteration (p < 0.1). Candidates were documented to be involved in cellular development, stress and cell death. Increase of stress related proteins and decrease of new glaucoma related candidates, ADP/ATP translocase 3 (ANT3), PC4 and SRFS1-interacting protein 1 (DFS70) and methyl-CpG-binding protein 2 (MeCp2) could be documented by MS. Moreover, candidates could be validated by Accurate Inclusion Mass Screening (AIMS) and immunostaining and supported for the retinal ganglion cell layer (GCL) by laser capture microdissection (LCM) in porcine and human eye cryosections. The workflow allowed a detailed view into the human retina proteome highlighting new molecular players ANT3, DFS70 and MeCp2 associated to glaucoma.

Systemic Associations of Exfoliation Syndrome

Exfoliation syndrome (XFS) is an age-related disease characterized by the production, deposition, and progressive accumulation of a white, fibrillar, extracellular material in many ocular tissues, most prominent on the anterior lens surface and pupillary border. Its prevalence increases steadily with age in all populations. It is the most common identifiable cause of open-angle glaucoma worldwide and is a potentially reversible or even curable disease. First described in Finland in 1917 by Lindberg, it has long been associated with open-angle glaucoma. However, in recent years, it is being increasingly reported in conjunction with a multiplicity of both ocular and systemic disorders, and the number of these is expected to grow, particularly with investigations based on attempts to associate other diseases with those genes known to be associated with XFS. Despite the focus on XFS as a cause of open-angle glaucoma for nearly a century, in reality it is still only an ocular manifestation of a protean systemic disease. It is a unique disorder with extensive and often serious ocular and systemic manifestations and not, as it has long been termed, a "form" or "type" of glaucoma. This misconception has delayed research into the molecular and cellular processes involved in its development, and the underestimation of its overall importance and its underlying causative mechanisms have largely been long ignored. The purpose of this article is to review the systemic disorders which are becoming increasingly associated with XFS. Reviews of epidemiology, genetics, biomarkers, molecular mechanisms of development, and ocular findings may be found elsewhere.

Amyloid β Peptides and Cognitive Functions in Patients with Pseudoexfoliation Syndrome

PURPOSE

The aim of this study was to evaluate if there is any relation between the Alzheimer's peptides (amyloid β-40 and β-42) concentration in plasma and aqueous humor as well as cognitive functions with pseudoexfoliation syndrome (PEX).

METHODS

One-hundred forty-two patients with PEX have been included for this study; median age: 75 years (Q1 = 71,5; Q3 = 80,0). Control group comprised 93 subjects aged 74 years (Q1 = 68,0; Q3 = 80,0). Amyloid β-40 and β-42 (Aβ-40, Aβ-42) concentrations were assessed in plasma in 73 PEX patients and 49 controls. Aβ-40 concentration in aqueous humor was measured in 31 patients from each group. Mini Mental State Examination (MMSE) and Clock Drawing Tests were performed in 83 PEX patients and 36 controls.

RESULTS

The differences between amyloid concentrations both in plasma and in aqueous humor in PEX and control groups were not statistically significant. There were no differences in MMSE and Clock Drawing Tests between groups.

CONCLUSION

Our results do not indicate any relation between PEX and Alzheimer's amyloids or cognitive functions in cataract patients.

Oral delivery of bioencapsulated proteins across blood-brain and blood-retinal barriers

Delivering neurotherapeutics to target brain-associated diseases is a major challenge. Therefore, we investigated oral delivery of green fluorescence protein (GFP) or myelin basic protein (MBP) fused with the transmucosal carrier cholera toxin B subunit (CTB), expressed in chloroplasts (bioencapsulated within plant cells) to the brain and retinae of triple transgenic Alzheimer's disease (3×TgAD) mice, across the blood-brain barriers (BBB) and blood-retinal barriers (BRB). Human neuroblastoma cells internalized GFP when incubated with CTB-GFP but not with GFP alone. Oral delivery of CTB-MBP in healthy and 3×TgAD mice shows increased MBP levels in different regions of the brain, crossing intact BBB. Thioflavin S-stained amyloid plaque intensity was reduced up to 60% by CTB-MBP incubation with human AD and 3×TgAD mice brain sections ex vivo. Amyloid loads were reduced in vivo by 70% in hippocampus and cortex brain regions of 3×TgAD mice fed with bioencapsulated CTB-MBP, along with reduction in the ratio of insoluble amyloid β 42 (Aβ42) to soluble fractions. CTB-MBP oral delivery reduced Aβ42 accumulation in retinae and prevented loss of retinal ganglion cells in 3×TgAD mice. Lyophilization of leaves increased CTB-MBP concentration by 17-fold and stabilized it during long-term storage in capsules, facilitating low-cost oral delivery of therapeutic proteins across the BBB and BRB.

Serum YKL-40 levels as a novel marker of inflammation and endothelial dysfunction in patients with pseudoexfoliation syndrome

PURPOSE

To evaluate serum levels of YKL-40 in patients with pseudoexfoliation syndrome (PEX) in comparison with those of age- and sex-matched healthy subjects.

METHODS

Forty patients with PEX (PEX group) and 40 age- and sex-matched control subjects (control group) were enrolled in the study. An enzyme immunoassay method using the commercially available test MicroVue YKL-40 was used to measure serum YKL-40 concentration. Systolic and diastolic blood pressures, serum levels of high sensitivity C-reactive protein (hsCRP), total cholesterol, low-density lipoprotein cholesterol (LDL), high-density lipoprotein cholesterol (HDL), and triglycerides were also examined.

RESULTS

The mean age was 54.4±7.6 (ranging 41-65) years in each group. The mean serum YKL-40 level of the PEX group was significantly higher than that of the control group (P<0.001). In addition, the mean serum HsCRP, total cholesterol, LDL, and triglycerides levels were significantly higher, and mean serum HDL level was significantly lower in the PEX group than in the control group (all P<0.001, excluding both P=0.002 for triglycerides and HDL levels). Further, the mean systolic and diastolic blood pressures were significantly higher in the PEX group than in the control group (P₁=0.001 and P₂=0.01, respectively).

CONCLUSION

We have shown a relationship between PEX and elevated serum levels of YKL-40. We imply that a better understanding of the role of YKL-40 in the pathogenesis of endothelial dysfunction and atherosclerosis is necessary to develop new therapies for preventing or treating PEX. Further studies are warranted to clarify the clinical relevance of these findings.

Distribution of amyloid precursor protein and amyloid-beta in ocular hypertensive C57BL/6 mouse eyes

PURPOSE

Amyloid precursor protein (APP) and amyloid-beta (Abeta) appear to participate in the pathophysiology of retinal ganglion cell (RGC) death in glaucoma. We, therefore, determined the distribution of APP and Abeta in the retinas of C57BL/6 mice after induction of chronic ocular hypertension.

METHODS

Ocular hypertension was induced in one eye of three-month-old C57BL/6 mice by injection of hypertonic saline into episcleral veins. After 6 weeks of documented elevated intraocular pressure (IOP), retinas were fixed with 4% paraformaldehyde and processed for immunohistochemistry with antibodies including a polyclonal antibody to the C-terminus of Abeta 40 (Novartis 17-40/23) and a polyclonal antibody to the APP ectodomain (Novartis 474). Distribution and semiquantitative expression of APP and Abeta immunolabeling in ocular hypertensive and control retinas were graded in a masked fashion and compared.

RESULTS

APP and Abeta immunoreactivity was found in the pia/dura, optic nerve (ON), and RGC layer of ocular hypertensive retinas, whereas APP and Abeta immunoreactivity in the contralateral control eyes was detected only in the pia/dura. Comparison of ocular hypertensive and control eyes for Abeta immunolabeling was significant in the ON and RGC layer (p < 0.05) whereas no significant difference was found when compared for APP staining.

CONCLUSIONS

High Abeta and APP levels were seen in ocular hypertensive retinas, probably due to abnormal APP-splicing in the presence of elevated IOP.

Detection of Alzheimer Peptides and Chemokines in the Aqueous Humor

Purpose

Alzheimer disease (AD) and age-related ocular diseases are characterized by inflammation and accumulation of insoluble proteins. We aimed to investigate the detectability and clinical relevance of a panel of AD-related markers, such as Alzheimer peptides and chemokines, in the aqueous humor (AH) samples taken from patients with cataract only, or cataract and 1 other ocular disease.

Methods

The AH samples were obtained during cataract surgery from patients with cataract only (n=162), cataract and glaucoma (n=21), cataract and exfoliation (PEX) (n=31), cataract and macular degeneration (n=36), and cataract and diabetic retinopathy (n=16). The AD peptides (Aβ1–42, Aβ1–40, Aβ1–38) and chemokines (eotaxin, eotaxin 3, interleukin [IL]-8, inducible protein-10, monocyte chemotactic protein [MCP]-1, MCP-4, macrophage-derived chemokine, macrophage inflammatory protein-1β, thymus and activation-regulated chemokine) were quantified by using multiplex immunoassays.

Results

The levels of the AH peptides (Aβ1–38, Aβ1–40, Aβ1–42) did not differ between disease groups. Independently of disease group, the Aβ1–38 levels correlated with Aβ1–40 and Aβ1–42 (p<0.001, n=277). Notably the ratio Aβ1–42 to Aβ1–38 differed between PEX and macular degeneration (mean 95% confidence interval [CI] = 8.12 [11.3–3.99] vs 2.23 [2.67–0.52], p=0.003). Among chemokines examined, only MCP-1 and IL-8 were detected in about 90% to 46% of all analyzed (n=266) samples. Higher levels of AH IL-8 were found in the glaucoma group than in cataract only (p=0.011). Independently of disease group, a correlation was observed between AH MCP-1 and IL-8 (rho=0.275, p<0.001, n=266) and between MCP-1 and Aβ1–40 (rho=0.239, p<0.001, n=266).

Conclusions

Our findings highlight pathologic similarities between AD and eye diseases, and show the potential of modern technologies to detect AD biomarkers in age-related eye diseases.

Retinal nerve fiber layer structure abnormalities in early Alzheimer's disease: evidence in optical coherence tomography

Alzheimer's disease (AD) patients often have visual disorders which may be due to retinal nerve degenerative changes. The aim of the current study was to determine the thickness changes of retina nerve fibers with optical coherence tomography (OCT) in AD patients. The OCT was used to assess the thickness of retinal nerve fiber layer (RNFL) from 22 AD patients and 22 healthy age-matched controls. The corrected visual acuity and intraocular pressure were measured and the dilated fundus examination and fundus image acquisition were also performed in those subjects. Compared with healthy age-matched controls, the RNFL thickness of AD patients were much thinner (p<0.05), especially in supra-retina and infra-retina, while no difference was found in the other retinal area. These changes were also confirmed by the fundus images. In conclusion, retinal nerve degeneration is present in the retina of AD patients and this degeneration is likely localized preferentially to the superior and inferior quadrant.

The evaluation of vestibular functions in patients with pseudoexfoliation syndrome

The main objective of the study is to evaluate vestibular system of the inner ear with postural tests in the patients with pseudoexfoliation syndrome (PEX). It is clinical case-control study. The study group included 34 patients with PEX and 40 controls without PEX. The patients and controls underwent complete ophthalmic and otorhinolaryngologic examinations. Vestibular functions were done by Fitzgerald and Dix-Hallpike, caloric tests, Romberg test, tandem Gait test, Quiks test in both control and study groups. Pur-tone and high-frequency audiography were also performed in all cases. The mean patient age was 63 years (+/-11.80) (range 47-74 years) in the PEX group and 65 years (+/-8.70) (range 61-68 years) in the control group with no differences among the two groups (P > 0.05). Although none of the 34 patients with PEX had clinical history of balance disturbance, 21 (61.76%) had significant pathologic sign in vestibular function tests (P < or = 0.05), while only 3 (7.5%) of 40 cases in the control group had pathologic sign in vestibular function tests. The scales from pure tone and high-frequency audiogram in the PEX group were similar to those of the control group. In conclusion, the patients with PEX, there may be a vestibular involvement in the pathological level in the inner ear. Larger clinical studies, experimental animal studies, and post mortem studies in humans are needed to disclose the pathology in the vestibulocochlear system in the patients with PEX.

Serum alpha-1-antitriypsin levels in patients with pseudoexfolative syndrome

PURPOSE

To evaluate the levels of serum alpha 1-antitrypsin in patients with pseudoexfoliation syndrome (PEX) and healthy control subjects without PEX.

MATERIAL AND METHODS

Forty-four patient with PEX and 40 healthy control subjects (84 subjects total) were enrolled into the study. Serum ATT levels were measured using nephelometry.

RESULTS

The mean serum AAT concentration in PEX group was significantly higher than in the controls (p=0.0001).

CONCLUSION

Serum AAT levels were found to be increased in patients with PEX. Increased serum AAT levels in PEX may explain the role of inflammation in this group of patients.

Sensorineural hearing loss in pseudoexfoliation syndrome

PURPOSE

To determine hearing thresholds at sound frequencies important for speech comprehension in subjects with ocular pseudoexfoliation and to compare them with that of age- and sex-matched controls without pseudoexfoliation.

DESIGN

Case-control study.

PARTICIPANTS

Eighty-three subjects with ocular pseudoexfoliation and 83 age- and gender-matched controls without pseudoexfoliation.

METHODS

Pure tone audiometry (air and bone conduction) was performed at 1, 2, and 3 kilohertzes in all subjects. Hearing thresholds were compared with an age- and gender-stratified standard (ISO7029) and between study groups.

MAIN OUTCOME MEASURES

Individual hearing thresholds at 1, 2, and 3 kilohertz and hearing loss, defined as the sum of tested thresholds lower than the ISO7029 standard median.

RESULTS

A total of 166 eligible subjects were evaluated. Equal numbers of male and female subjects were allocated into each of the study groups (60 male and 23 female subjects in either group). Mean ages of male and female participants did not significantly differ in cases versus controls (P = 0.88 and P = 0.83). Below average hearing thresholds were present in 88.4% of examined ears in the case group, versus 53.6% in the control group (P<0.001; odds ratio [OR], 6.69; 95% confidence interval [CI], 3.49-11.79). Overall, 78 subjects (94.0%) in the case group, versus 58 subjects (69.9%) in the control group, had below average hearing in one or both ears (P<0.001; OR, 6.72; 95% CI, 2.42-18.62). Hearing thresholds at each of the examined frequencies and the total threshold were also significantly higher in individuals with pseudoexfoliation. Although glaucoma was significantly more common in subjects with pseudoexfoliation, it was not associated with below average hearing in any of the study groups.

CONCLUSIONS

Hearing thresholds at frequencies that are important for speech comprehension are significantly worse in individuals with ocular pseudoexfoliation than in matched controls. This finding may support the multiorgan nature of pseudoexfoliation syndrome.

Vitamin deficiency and hyperhomocysteinemia in pseudoexfoliation glaucoma

Pseudoexfoliation syndrome (PEX) is a systemic disorder characterized by the deposition of an abnormal fibrillar material in ocular and various extraocular tissues. It represents the most common identifiable cause of glaucoma (PEX glaucoma = PEXG). Due to similar pathogenetic mechanisms, glaucoma has been called "ocular Alzheimer's disease". PEXG and Alzheimer's disease share common associations such as the higher prevalence of hyperhomocysteinemia in both disorders. In order to investigate the cause of hyperhomocysteinemia in PEXG, we evaluated B-vitamin levels (folate, B12, B6) and their associations with homocysteine (Hcy) in plasma of 70 PEXG patients and 70 control subjects. Folate, vitamin B12 and B6 levels were significantly decreased and associated with elevated Hcy levels in PEXG. Low B-vitamin levels in PEX might also help explain, at least in part, the higher prevalence of B-vitamin deficiency in disorders associated with PEX such as Alzhemier's disease.

Pseudoexfoliation syndrome and its antioxidative protection deficiency as risk factors for age-related cataract

PURPOSE

Pseudoexfoliation syndrome (PES) seems to be a systemic condition. However, to an ophthalmologist it represents a continual challenge, due to unclear etiology and patho-genesis, and because of a potential for development of an aggressive glaucoma, and cataract surgery complications. According to some findings, PES could be a factor of hastened aging, which means that it could be considered as a secondary aging factor.

METHODS

Frequencies of secondary aging diseases (non-insulin dependent diabetes mellitus, atherosclerotic myocardiopathy, chronic obstructive lung diseases, arterial hypertension, and PES) were investigated in 162 patients with age-related cataract and 55 age- and sex-matched control subjects, and analyzed by a logistic regression. The authors also determined elements of antioxidative protection in a group of sera from patients with cataract and PES, and compared them to those obtained from patients with cataract without PES (activity of catalase and peroxidase, glutathione, vitamins C and E), and total antioxidative protection (%iMDA). Antioxidant defense of aqueous humors, expressed as a rate of induced malondialdehyde (%iMDA), and total thiol groups in the lens corticonuclear blocks (TSH) were estimated in samples of 17 patients with PES and cataract and 55 patients with cataract only.

RESULTS

Logistic regression showed the highest odds ratio for PES (OR=4.516; p<0.05). Catalytic activity of serum catalase had significantly lower values in patients with PES (p<0.05). Anti oxidative defense of aqueous humor and lens had lower values in patients with PES.

CONCLUSIONS

The results indicate that PES might be a significant factor for cataractogenesis. At least a part of pathogenesis alterations in an eye with PES could be the result of higher intensity of oxidative stress.

Secreted leukocyte protease inhibitor is present in aqueous humours from cataracts and other eye pathologies

Previous studies identified serine, cysteine and metalloproteases in normal aqueous humours (AH) and suggested that a balance between proteases and their inhibitors may play a role in the modulation of the AH outflow. We aimed to determine whether secretory leukocyte protease inhibitor (SLPI), a serine protease inhibitor, is present in AH of patients with cataract and other eye pathologies. AH was collected from 117 cataract patients of which 55 were diagnosed with more when one eye disease: cataract only (n=62), pseudoexfoliation (PEX) (n=26), glaucoma (n=6), diabetes retinopathy (n=4), iritis-uveitis (n=4) and macular degeneration (n=28). The total protein in AH was determined by a Bradford assay and SLPI was analyzed by Western blot and ELISA methods. The average concentration of total protein and SLPI in AH samples was 160+/-15 microg/ml (n=117, +/-SEM) and 500+/-94 pg/ml (n=105), respectively. The cataract patients with additional eye disease(s) showed higher protein levels (201+/-35 microg/ml) than cataract (controls) (128+/-31 microg/ml), P<0.01. It is noteworthy that no correlation was found between SLPI and the total protein concentrations in AH, but SLPI was positively correlated with age (r=0.2, P<0.05). No statistical difference in SLPI levels was found between controls (cataract) and other pathologies, while patients with iritis/uveitis had higher SLPI levels compared to those with diabetes (P<0.05). We show here for the first time that SLPI is present in AH and may play a role as well as serve as a marker in pathological states.

Effects of apolipoprotein E genotypes on the development of exfoliation syndrome

Apolipoprotein E (apo E) is directly involved in the amyloid deposition and fibril formation and is present in many cerebral and systemic amyloidoses immunologically. It is encoded by a polymorphic gene and it has three common alleles-epsilon2, epsilon3, and epsilon4. Exfoliation syndrome (XFS) is characterized by the deposition throughout the body of focal fibrillogranular aggregates in which there have been some reports of amyloid or amyloid-like features. We evaluated the possible association between apo E polymorphism and the occurrence of XFS. Using High Pure PCR Template Preparation Kits, genomic DNAs were extracted from whole blood and apo E polymorphisms were determined by using Lightcycler-Apo E Mutation Detection Kits in 76 patients with XFS and 74 controls. The E2/E2, E2/E3 and E2/E4 genotypes (OR 29.9, 95% CI 3.1-293.7; OR 56.1, 95% CI 12.5-252.7; OR 43.9, 95% CI 7.4-257.6, respectively) and the in2 allele are found to have an increased risk of developing XFS (p=0.0001); whereas the in3 allele was found to be protective (p=0.0001). Apo E polymorphism and the presence of in2 allele are seem to be significantly associated with the development of XFS.

Ocular static and dynamic light scattering: a noninvasive diagnostic tool for eye research and clinical practice

The noninvasive techniques of static and dynamic light scattering are emerging as valuable diagnostic tools for the early detection of ocular and systemic diseases. These include corneal abnormalities, pigmentary dispersion syndrome, glaucoma, cataract, diabetic vitreopathy, and possibly macular degeneration. Systemic conditions such as diabetes and possibly Alzheimer's disease can potentially be detected early via ocular tissues. The current state of development of these techniques for application to ophthalmic research and ultimately clinical practice is reviewed.