Increased aqueous humor basic fibroblast growth factor and hyaluronan levels in relation to the exfoliation syndrome and exfoliative glaucoma

Pressure-Related Effects on Homeostatic Müller Cell Proteins in the Adult Porcine in Vitro Retina

PURPOSE

To explore early pressure-related effects on Müller cell homeostatic proteins in the in vitro adult porcine retina.

METHODS

Retinal explants were subjected to 0-, 10-, 30-, or 60-mmHg of pressure for 24 or 48 h in culture. Retinal explants fixed immediately after enucleation were used as controls. Müller cell proteins were evaluated by GFAP, GS, CRALBP, and bFGF immunohistochemistry.

RESULTS

GFAP-labeling revealed no differences in fluorescence intensity after 24 or 48 h in any of the pressure groups compared with control retinas. However, a higher intensity was found in the 30- and 60-mmHg groups compared with 0-mmHg counterparts after 24 and 48 h. A higher intensity in GS-labeled sections was found in the 10-and 60-mmHg groups compared with controls and remaining pressure groups after 48 h. Compared with control retinas, CRALBP labeling revealed a higher intensity in the 60-mmHg group after 24 h and in the 10-, 30-, and 60-mmHg groups after 48 h. After 24 and 48 h, a lower intensity was found in bFGF-labeled cells in the 0-, 10-, and 30-mmHg groups compared with controls, while no difference was seen for the 60-mmHg group.

CONCLUSIONS

Müller cells in the cultured porcine adult retina respond early to pressure by altering the expression of GFAP as well as the homeostatic proteins GS, CRALBP, and bFGF.

Pseudoexfoliation syndrome: The critical role of the extracellular matrix in pathogenesis and treatment

Pseudoexfoliation syndrome (PEXS) is an age-related condition manifesting mainly in ocular tissues. PEXS is manifested through excess aggregation of fibrillary extracellular material at the anterior part of the eye that consists of a plethora of biomolecules, such as different proteoglycans (PGs) and glycosaminoglycans. PEXS is often linked to increased intraocular pressure, and can also lead to pseudoexfoliation glaucoma with very poor prognosis. Various stimuli are known to affect PEXS, including oxidation stress (OS), UV radiation and osmotic pressure. OS, is prominently involved on the progression of the syndrome as it promotes fibrogenesis, possibly via the induction of transforming growth factor-β (TGF-β) and other biomolecular effectors. In addition, PEXS initiation is tightly connected with the dysregulation of extracellular matrix (ECM) homeostasis since aberrant expression of ECM molecules is linked to both the accumulation and low degradation of pseudoexfoliation material. This article aims at uncovering the crucial role of various ECM effectors such as lysyl oxidase-like proteins, matrix metalloproteinases, and TGF-β1, as well as the biochemical pathways involved in the development and the progression of the PEXS.

Early-onset Exfoliation Syndrome: A Literature Synthesis

PRECIS

We conducted a literature review of younger patients with exfoliation syndrome (XFS) in an attempt to identify case similarities and better understand disease etiology.

PURPOSE

XFS that predisposes to secondary glaucoma is a strongly age-related condition. We performed a literature review of XFS and exfoliation glaucoma (XFG) in patients aged younger than 40 years to examine potential common characteristics and gain clues to its etiology.

METHODS

We conducted a broad literature search with appropriate keywords and manually extracted key demographic and ocular features on younger XFS and XFG cases. Articles that did not provide past ocular history on early-onset XFS/XFG were excluded.

RESULTS

We identified 12 cases of XFS and XFG in patients from 13 to 40 years old (8 females; 11 White; 5 from Iran). All had past ocular history remarkable for intraocular surgery for other glaucoma conditions (7 cases), other ocular diseases (3 cases), or ocular trauma (2 cases).

CONCLUSIONS

All reported early-onset XFS and XFG cases arise in the setting of events that produced a significant disruption of the blood-aqueous barrier. Understanding the metabolic alterations of aqueous humor from such cases could provide clues regarding how exfoliation material forms.

Distribution and Function of Glycosaminoglycans and Proteoglycans in the Development, Homeostasis and Pathology of the Ocular Surface

The ocular surface, which forms the interface between the eye and the external environment, includes the cornea, corneoscleral limbus, the conjunctiva and the accessory glands that produce the tear film. Glycosaminoglycans (GAGs) and proteoglycans (PGs) have been shown to play important roles in the development, hemostasis and pathology of the ocular surface. Herein we review the current literature related to the distribution and function of GAGs and PGs within the ocular surface, with focus on the cornea. The unique organization of ECM components within the cornea is essential for the maintenance of corneal transparency and function. Many studies have described the importance of GAGs within the epithelial and stromal compartment, while very few studies have analyzed the ECM of the endothelial layer. Importantly, GAGs have been shown to be essential for maintaining corneal homeostasis, epithelial cell differentiation and wound healing, and, more recently, a role has been suggested for the ECM in regulating limbal stem cells, corneal innervation, corneal inflammation, corneal angiogenesis and lymphangiogenesis. Reports have also associated genetic defects of the ECM to corneal pathologies. Thus, we also highlight the role of different GAGs and PGs in ocular surface homeostasis, as well as in pathology.

Methods to Induce Chronic Ocular Hypertension: Reliable Rodent Models as a Platform for Cell Transplantation and Other Therapies

Glaucoma, a form of progressive optic neuropathy, is the second leading cause of blindness worldwide. Being a prominent disease affecting vision, substantial efforts are being made to better understand glaucoma pathogenesis and to develop novel treatment options including neuroprotective and neuroregenerative approaches. Cell transplantation has the potential to play a neuroprotective and/or neuroregenerative role for various ocular cell types (e.g., retinal cells, trabecular meshwork). Notably, glaucoma is often associated with elevated intraocular pressure, and over the past 2 decades, several rodent models of chronic ocular hypertension (COH) have been developed that reflect these changes in pressure. However, the underlying pathophysiology of glaucoma in these models and how they compare to the human condition remains unclear. This limitation is the primary barrier for using rodent models to develop novel therapies to manage glaucoma and glaucoma-related blindness. Here, we review the current techniques used to induce COH-related glaucoma in various rodent models, focusing on the strengths and weaknesses of the each, in order to provide a more complete understanding of how these models can be best utilized. To so do, we have separated them based on the target tissue (pre-trabecular, trabecular, and post-trabecular) in order to provide the reader with an encompassing reference describing the most appropriate rodent COH models for their research. We begin with an initial overview of the current use of these models in the evaluation of cell transplantation therapies.

Growth Factors, Oxidative Damage, and Inflammation in Exfoliation Syndrome

Exfoliation syndrome (XFS) produces deleterious ocular aging and has protean systemic manifestations. Local ocular production of TGFβ1 is of central importance in XFS. TGFβ1 appears to induce the expression of LOXL1 and the production of other extracellular matrix components which are known to be present in exfoliation material. Furthermore, results from several studies find that the aqueous humor of exfoliation glaucoma patients exhibits a decreased antioxidant defense and increased oxidative stress systems. Finally, studies show that the levels of interleukin-6 and interleukin-8 in the aqueous humor of XFS patients were 3-fold higher than in controls. Overall TGFβ1, as well as a prooxidative and proinflammatory environment seems to play an important role in XFS.

Serum insulin-like growth factor-1 levels in patients with pseudoexfoliation syndrome and glaucoma

Insulin-like growth factor-1 (IGF-1) is altered in several neurodegenerative diseases, the association between serum IGF-1 levels and glaucoma has not been evaluated. This study was designed to evaluate whether serum IGF-1 levels are different in patients with Pseudoexfoliation (PEX) with or without glaucoma. The study was conducted with 110 participants aged 65 years or older who were divided into three groups: group 1, patients with PEX syndrome; group 2, patients with PEX glaucoma; and group 3, participants without PEX or glaucoma. All participants underwent full ophthalmological examination and a detailed medical history was recorded. Patients with known neurodegenerative diseases other than PEX glaucoma were excluded. Serum IGF-1 levels were measured by automated chemiluminescent assay. Groups 1, 2, and 3 included 35, 34, and 41 patients, respectively; there were no differences regarding age, gender, or systemic disease status. There were also no statistically significant differences between the groups in terms of IGF-1 levels, which were 91.7 ± 39.1, 101.1 ± 40.2, and 107.2 ± 43.8 ng/ml for groups 1, 2, and 3, respectively (p = 0.276). Serum IGF-1 levels were similar by gender, the presence of systemic disease, status of diabetes mellitus, and laterality of the PEX material. There was no correlation between the cup-to-disk ratios and IGF-1 levels (r = -0.214, p = 0.223). IGF-1 levels in the circulation did not differ in the presence of PEX syndrome with or without glaucoma. This may indicate that the neurodegenerative process is local rather than systemic.

Prediction of Pseudoexfoliation Syndrome and Pseudoexfoliation Glaucoma by Using Neutrophil to Lymphocyte Ratio and Platelet to Lymphocyte Ratio

PURPOSE

To assess the levels of neutrophil to lymphocyte ratio (NLR) and platelet to lymphocyte ratio (PLR) in patients with pseudoexfoliation syndrome (PEX) and to compare the NLR and PLR results of patients with PEX, PEX glaucoma (PXG), and healthy controls.

METHODS

In total, 34 patients with PEX, 29 patients with PXG, and 42 healthy subjects were enrolled in this retrospective study. Complete ophthalmologic examination and complete blood count measurements were performed of all subjects. Complete blood counts were performed within 2 h of blood collection.

RESULTS

There was a significant difference in NLR between PEX and control groups (p = 0.012) and PXG and control groups (p = 0.003). Also, a significant difference was found in PLR values between control and PXG groups (p = 0.024).

CONCLUSIONS

Our study for the first time provides evidence that PLR and NLR may be useful for predicting the prognosis of PEX patients and progression to PXG.

Prevalence and Prognosis of Pseudoexfoliation Glaucoma in Western India

PURPOSE

To investigate the prevalence and reconnoiter treatment modalities for Pseudoexfoliation Glaucoma (PXG) in subjects with Pseudoexfoliation Syndrome (PXF) in a rural scenario of western India.

DESIGN

A prospective prevalence study.

METHODS

Occurrence of PXG in 250 subjects with PXF was studied in the Department of Glaucoma, Shri Ganapati Netralaya, Jalna, India, from 2009 to 2011. The subject pool presented with PXF, having intraocular pressure (IOP) ≥ 20 mm of Hg, and evidencing optic nerve damage and abnormal visual fields were judiciously selected as PXG cohorts. A decision table is formulated to assist the physician in rendering medical or surgical treatment options.

RESULTS

The prevalence of PXG increased with increasing age at 30% (95% CI: 28.56-33.72) in the 60-year-old and older population. It was predominantly higher in cohorts involved in outdoor physical activities at 46% (95% CI: 41.24-52.38). The eminence and prevalence of nuclear cataract in subjects with PXG was 72 % (95% CI: 65.72-76.34). Visual impairment was highly prevalent in 75% (95% CI: 73.43-78.29) and 10% (95% CI: 6.87-13.21) cohorts with PXG and PXF respectively. In general, linear modelling IOP was 26.37±1.64 in subjects with PXG, which was managed to 16.50±1.32 after rendering our adapted treatment protocols.

CONCLUSIONS

Increased IOP, occludable angles, and glaucomatous optic neuropathy occur more frequently in the population with PXF. It is inferred that that treatment protocol of combined cataract and glaucoma surgery gives maximum reduction in IOP.

FACE analysis as a fast and reliable methodology to monitor the sulfation and total amount of chondroitin sulfate in biological samples of clinical importance

Glycosaminoglycans (GAGs) due to their hydrophilic character and high anionic charge densities play important roles in various (patho)physiological processes. The identification and quantification of GAGs in biological samples and tissues could be useful prognostic and diagnostic tools in pathological conditions. Despite the noteworthy progress in the development of sensitive and accurate methodologies for the determination of GAGs, there is a significant lack in methodologies regarding sample preparation and reliable fast analysis methods enabling the simultaneous analysis of several biological samples. In this report, developed protocols for the isolation of GAGs in biological samples were applied to analyze various sulfated chondroitin sulfate- and hyaluronan-derived disaccharides using fluorophore-assisted carbohydrate electrophoresis (FACE). Applications to biologic samples of clinical importance include blood serum, lens capsule tissue and urine. The sample preparation protocol followed by FACE analysis allows quantification with an optimal linearity over the concentration range 1.0–220.0 µg/mL, affording a limit of quantitation of 50 ng of disaccharides. Validation of FACE results was performed by capillary electrophoresis and high performance liquid chromatography techniques.

Aqueous humor and plasma levels of vascular endothelial growth factor and nitric oxide in patients with pseudoexfoliation syndrome and pseudoexfoliation glaucoma

PURPOSE

To investigate levels of vascular endothelial growth factor (VEGF) and nitric oxide (NO) in the aqueous humor and plasma of patients with pseudoexfoliation syndrome (PXS) and pseudoexfoliation glaucoma (PXG), compared with controls.

METHODS

This prospective study involved 37 patients with PXS, 15 with PXG, and 32 control subjects in whom cataract surgery was indicated. Aqueous humor and plasma VEGF and NO levels were measured with enzyme-linked immunosorbent assay and chemiluminescence methods, respectively.

RESULTS

Aqueous humor and plasma VEGF concentrations were higher in patients with PXS and PXG than in controls (P<0.001). Aqueous humor NO concentrations were higher in patients with PXS and PXG than in controls (P<0.05 and P=0.001, respectively). Plasma NO concentrations did not differ between the 3 groups. Aqueous humor and plasma VEGF and NO levels were not significantly different in patients with PXS versus PXG. VEGF and NO levels showed no significant correlation among the 3 groups (P>0.05).

CONCLUSIONS

Elevated aqueous humor VEGF and NO levels and plasma VEGF concentrations in eyes with PXS and PXG can be explained by the ischemic nature of these disorders. The lack of correlation between VEGF and NO levels may indicate impaired downregulation, which may have a role in the progression to PXG.

Pseudoexfoliation as a risk factor for peripheral vascular disease: a case-control study

AIM

To determine the association between pseudoexfoliation (PEX) and peripheral vascular disease (PVD) among age-related cataract.

SETTING

Iladevi Cataract and IOL Research Center, Ahmedabad, India.

MATERIAL AND METHODS

An observational age-matched case-control study of 160 patients over 60 years of age with age-related cataract. A total of 40 subjects with PEX (cases) were compared with 120 subjects with cataract but without PEX (controls). A detailed medical history, including hypertension, diabetes mellitus, cerebrovascular stroke and ischaemic heart disease, was recorded. Ankle brachial index (ABI) was used to determine the risk of PVD among age-related cataract patients. Color Doppler imaging was performed on the brachial and dorsalis pedis artery to measure ABI and detect PVD. Least mean ABI was the main outcome measure, as low ABI indicates higher risk for PVD. The lowest mean ABI was measured for each subject. An ABI ratio of <0.90 was considered abnormal. The Mann-Whitney U-test and logistic regression were used for analysis.

RESULTS

The lowest mean ABI in the controls was 0.98 ± 0.03 (SD; a range of 0.86-1.08) as compared with 0.88 ± 0.02 (SD) among the cases (a range of 0.79-0.92; P < 0.001). When compared with controls, cases had a lower ABI (P < 0.001) irrespective of the presence or absence of systemic illness. On multiple regression analysis adjusting for systemic illness, the presence of PEX increased the odds of a low ABI group 150 times (P < 0.001).

CONCLUSION

Subjects with cataract and PEX had a significantly lower ABI as compared with controls (cataracts without PEX). PEX is associated with and may be a risk factor for PVD.

Aqueous humor rapidly stimulates myocilin secretion from human trabecular meshwork cells

Myocilin, a protein associated with the development of glaucoma, is expressed in most eye tissues with highest expression observed in trabecular meshwork cells. In culture, primary human trabecular meshwork cells incubated in 10% fetal bovine serum have reduced myocilin expression compared to in vivo, but incubation in human aqueous humor, their normal in vivo nutrient source, restores myocilin expression to near in vivo levels. To investigate the mechanism by which human aqueous humor stimulates myocilin accumulation in conditioned media from normal human trabecular meshwork cells, three independent trabecular meshwork cell lines were cultured in Dulbecco's Modified Eagle's Medium (DMEM) containing various supplements: fetal bovine serum (10%), human serum (0.2%), porcine aqueous humor (50%), bovine serum albumin (0.1%), dexamethasone (10(-7)M), human aqueous humor (50%) or heat-inactivated human aqueous humor (50%). Conditioned media from cultured primary trabecular meshwork cells following incubation in human aqueous humor showed significant accumulation of myocilin in a time- (15 min) and dose-dependent manner (half maximal effective concentration ∼ 30%) while intracellular myocilin levels decreased. Minimal myocilin accumulation was observed in conditioned media isolated from trabecular meshwork cells cultured in DMEM containing fetal bovine or human serum, bovine serum albumin, porcine aqueous humor, dexamethasone or DMEM alone. Heat inactivation of human aqueous humor nearly eliminated human aqueous humor-stimulated myocilin secretion. Inhibitors of new protein synthesis, gene transcription, the endoplasmic reticulum/Golgi system and endocytic/exocytic secretory pathways failed to inhibit human aqueous humor-stimulated myocilin secretion. Using immunolabeling and transmission electron microscopy, myocilin was found associated with 70-90 nm vesicle-like structures within the cytoplasm of human aqueous humor treated trabecular meshwork cells. These studies suggest that myocilin secretion from trabecular meshwork cells occurs in a Golgi-independent manner following human aqueous humor treatment. Heat-labile factors in human aqueous humor are responsible for the time- and dose-dependent release of myocilin from vesicle-like structures within the cytoplasm of trabecular meshwork cells.

Retinal nerve fiber layer thickness in patients with exfoliation, exfoliative glaucoma, and primary open angle glaucoma

PURPOSE

to evaluate the retinal nerve fiber layer(RNFL) profile of healthy controls, persons with exfoliation syndrome (XFS), and patients with exfoliation glaucoma (XFG) and primary open angle glaucoma(POAG).

METHODS

One eye from each of 269 participants was analyzed. Fifty eyes were normal , 45 eyes had XFS, 89 eyes had POAG, and 89 had XFG. Glaucoma patients were divided according to the severity of the disease into mild and advanced groups. All participants underwent imaging with the GDx-VCC device. Measurements of the parameters TSNIT average, TSNIT SD, and nerve fiber indicator (NFI) were performed. Polametric RNFL thickness values were compared by means of Bonferroni-corrected t-tests.

RESULTS

Regarding control and glaucoma groups, statistically significant differences were identified in all GDx parameters. RNFL thickness values of the control group differed significantly from the values of the XFS group. There was no statistically significant difference between RNFL thickness values for the mild POAG and mild XFG groups or for the advanced POAG and advanced XFG groups.

CONCLUSIONS

Polarimetry-determined RNFL in eyes with XFS is thinner than that of healthy eyes. No differences in RNFL thickness were found when eyes with POAG and XFG of similar severity were compared.

Glutathione and Lipid Peroxide Changes in Pseudoexfoliation Syndrome

PURPOSE

To investigate the oxidative status of the aqueous humor of patients with pseudoexfoliation (PEX) syndrome.

METHODS

Aqueous humor samples obtained during cataract surgery of patients with PEX syndrome and normal age-matched control subjects were examined for changes in the levels of glutathione (GSH), glutathione disulfide (GSSG), and TBA reactive species (TBARS), products of lipid peroxidation. GSH, GSSG, and TBARS were determined by specific fluorescent assays.

RESULTS

Compared to normal controls, PEX syndrome aqueous humor samples showed a decrease of up to 28% of GSH concentration, and GSSG was increased up to 23%. The ratio of GSH/GSSG was 1.7-fold decreased in PEX syndrome samples. TBARS levels were increased by 100% in the PEX aqueous humor samples as compared to the controls.

CONCLUSIONS

High levels of GSSG and TBARS indicate high oxidative stress, as well as the decrease in the ratio of GSH/GSSG. Our findings suggest a role for oxidation stress in the pathogenesis and the progression of PEX syndrome.

Changes in HNK-1 epitope and collagen type IX in the aqueous humour of patients with pseudoexfoliation syndrome

PURPOSE

To investigate alterations in the proteoglycan (PG) and glycosaminoglycan (GAG) content of the aqueous humour in patients with pseudoexfoliation syndrome (PEX).

MATERIALS AND METHODS

Aqueous humor samples were obtained during cataract surgery from nineteen patients bearing PEX features and twenty-three age-matched normal controls. Protein and IgG were quantified densitometrically after their electrophoretic separation. Collagen type IX, 3-sulphoglucuronic acid (HNK-1 epitope), biglycan and heparan sulphate proteoglycans were detected in Western and dot blots by using specific monoclonal antibodies (MAbs). The immunochemical analysis was performed in native aqueous humour or after degradation of the glycosaminoglycans with chondroitinases.

RESULTS

Degradation of the samples with chondroitinases ABC, AC and B revealed that, in the aqueous humour from PEX eyes, collagen type IX and biglycan had a more dermatan sulphate than did normal eyes. In addition, more HNK-1 epitope was observed in PEX eyes, which after similar enzymatic treatment was found to be located mainly in dermatan sulphate sequences. 3-sulphoglucuronic acid was a constituent of the GAG chains of the collagen type IX. We found that the electrophoretic mobility of the bands of collagen type IX and HNK-1 epitope was exactly the same in the aqueous humour of normal and PEX samples; both migrated as four bands at 120, 113, 92.6 and 56 kDa. The PGs bearing heparan sulphate were found only in normal samples. Other PGs were not detected.

CONCLUSIONS

Because no significant difference was observed in the concentration of albumin and IgG in PEX and normal samples, the blood-aqueous barrier was probably not significantly compromised in PEX patients with cataract but without open-angle glaucoma. The results support the hypothesis that the pathogenesis of PEX can be linked to disturbed metabolism of GAGs and PGs.

Pseudoexfoliation syndrome prevalence in Greek patients with cataract and its association to glaucoma and coronary artery disease

PURPOSE

To investigate the prevalence of glaucoma and coronary artery disease (CAD) in patients with cataract and pseudoexfoliation (PEX) syndrome.

METHODS

Cross-sectional study of 2140 consecutive patients with cataract admitted at the University Hospital of Patras, Greece, for cataract surgery. Only patients with senile cataract were included in this study. All patients underwent a complete ophthalmological examination that included slit-lamp evaluation with dilated pupil for PEX material in the anterior segment, intraocular pressure (IOP) measurements, and optic disc cup examination. They also underwent an evaluation for CAD by a cardiologist. CAD was considered present if a patient had a history of myocardial infarction, or ischaemia, or abnormal coronary angiography. The patients were classified into two groups: the PEX and the non-PEX group.

RESULTS

One thousand and eighty-eight (50.8%) patients were men and 1052 (49.2%) were women. The overall prevalence of PEX syndrome was found to be 27.9% and it was found to increase with progressing age. Bilateral PEX was more frequent than unilateral PEX, with the percentage of bilateral PEX raising with progressing age. A total of 132 patients (22.1%) in the PEX group exhibited glaucoma, while in the non-PEX group only 2.5% suffered glaucoma. PEX was also found to be positively associated with the risk for CAD among subjects 50 years or older. No association between CAD and glaucoma was found.

CONCLUSIONS

PEX syndrome constitutes a major glaucoma risk factor and a CAD risk factor. Patients with PEX should be informed and examined frequently as the risk is present throughout.

Ocular and systemic pseudoexfoliation syndrome

PURPOSE

To provide an update on most recent developments regarding ocular and systemic manifestations and complications, clinical diagnosis and management, and molecular pathophysiology of pseudoexfoliation (PEX) syndrome, and to discuss future tasks and challenges in this field.

DESIGN

Perspective.

METHODS

Review of recent literature and authors' own clinical and laboratory studies.

RESULTS

PEX syndrome is a common age-related generalized fibrotic matrix process of worldwide significance, which may not only cause severe chronic open-angle glaucoma and cataract, but also a spectrum of other serious spontaneous and surgical intraocular complications. Recent progress and advances have led to (1) improvements in clinical management by understanding the effects of the PEX process on ocular tissues, by refining diagnostic criteria, by applying new treatment regimes, and by developing preventive strategies to reduce surgical complications; (2) increasing evidence for systemic associations of PEX with cardiovascular and cerebrovascular morbidity; and (3) new insights into the molecular pathophysiology by analyzing the composition of PEX material, the differential gene expression of affected tissues, and key factors involved in pathogenesis. The current pathogenetic concept describes PEX syndrome as an elastic microfibrillopathy involving transforming growth factor-beta1, oxidative stress, and impaired cellular protection mechanisms as key pathogenetic factors.

CONCLUSIONS

Future tasks and challenges comprise epidemiologic prevalence and genetic studies of PEX syndrome, prospective randomized clinical and histopathological screening studies on its systemic manifestations and associations, and intensified basic research on differential protein and gene expression, animal and in vitro models, as well as potential biomarkers for PEX syndrome and its associated glaucoma.

Superoxide dismutase activity in the lens capsule of patients with pseudoexfoliation syndrome and cataract

PURPOSE

To evaluate the activity of the antioxidative enzyme superoxide dismutase (SOD) in the anterior lens capsule of patients with cataract complicating pseudoexfoliation syndrome (PEX) in an attempt to determine the role of the oxidative mechanisms in the etiopathogenesis of this disorder.

SETTING

Departments of Ophthalmology and Biochemistry, Ankara University School of Medicine, Ankara, Turkey.

METHODS

At the beginning of phacoemulsification surgery, the anterior lens capsules in 21 eyes with PEX and cataract (group A) and those in 24 eyes with cataract alone (group B) were collected with continuous curvilinear capsulorhexis and were frozen at -20 degrees C. At the time of analysis, the specimens were thawed and centrifuged and the supernatants of the homogenate obtained from the samples were analyzed for the activity of the enzyme SOD.

RESULTS

The mean age of patients was 74.8 years +/- 5.5 (SD) in group A and 71.7 +/- 5.6 years in group B. The specific activity of SOD was 17.6 +/- 10.8 IU/mg and 4.36 +/- 1.80 IU/mL in group A and 9.9 +/- 12.9 IU/mg and 2.71 +/- 2.61 IU/mL in group B. Superoxide dismutase activity was significantly higher in group A patients than in group B patients (P = .022 and P = .011, respectively).

CONCLUSIONS

The increase in SOD activity in the lens capsule of patients with PEX and cataract suggests that oxidative mechanisms play a role in the etiopathogenesis of cataract in PEX. This suggests that SOD activity may be increased as a compensatory mechanism to eliminate this oxidative stress.

Collagen type IX and HNK-1 epitope in tears of patients with pseudoexfoliation syndrome

Pseudoexfoliation syndrome (PEX) is an age-related condition, which may cause open-angle glaucoma and has increasing interest since it seems to affect additional human tissues, i.e., cardiovascular tissue, skin, and still lacks elucidated pathogenesis. Collagen type IX and HNK-1 epitope have been considered characteristic constituents of the aqueous humour of PEX patients, since their amounts were increased in PEX aqueous humour compared to normal eyes. Since it has been proposed that the initial manifestations of PEX syndrome occur in conjunctiva, the present study was undertaken to investigate the presence of the same antigens in tears of PEX patients and their possible use as the biochemical markers for early diagnosis. Tears of PEX patients and healthy individuals were subjected to western blotting analysis for various basement membrane components identified in aqueous humour. It was found that collagen type IX and HNK-1 epitope were present in tears, the amount of the former being increased 2.7 times compared to normal (P<0.05), surprisingly high as compared with total protein or lysozyme activity in tears, which were found to be increased in PEX patients about 25% with no statistical differences (P approximately 0.4). The results suggest the possible use of tears' collagen type IX for the diagnosis of PEX syndrome.

Concentration of hyaluronic acid in primary open-angle glaucoma aqueous humor

We compared the concentration of hyaluronic acid in the aqueous humor of primary open-angle glaucoma (POAG) patients and non-glaucomatous patients. Aqueous humor samples were obtained from 22 patients just before trabeculectomy for clinically uncontrolled POAG (POAG group). Aqueous humor (0.1 mL) was aspirated by inserting a 26-gauge needle into the anterior chamber. The same procedure was performed for 22 non-glaucomatous patients just before cataract surgery (control group). Immediately after collection, the aqueous humor was stored at -20 degrees C. The concentration of hyaluronic acid was determined by a sensitive, noncompetitive and nonisotopic fluoroassay. The median (range) concentrations of hyaluronic acid of the POAG and control groups were 298.4 microg L(-1) (99.0-743.7 microg L(-1)) and 545.1 microg L(-1) (145.0-2366.0 microg L(-1)), respectively. The difference in concentrations of hyaluronic acid between the groups was statistically significant (P<0.001). In conclusion, the concentration of hyaluronic acid in the aqueous humor in POAG patients is lower than in non-glaucomatous patients. Further studies are necessary to determine the role of hyaluronic acid in the pathophysiology of POAG.

Elevated aqueous humour tissue inhibitor of matrix metalloproteinase-1 and connective tissue growth factor in pseudoexfoliation syndrome

BACKGROUND/AIMS

Pseudoexfoliation syndrome (PXF) was recently found to be associated with increased expression of transforming growth factor beta(1) (TGFbeta(1)) in the aqueous humour. As concern has been raised regarding anti-TGFbeta therapy, which can potentially disrupt the maintenance of anterior chamber associated immune deviation, the authors explored the levels of tissue inhibitor of matrix metalloproteinase-1 (TIMP-1), matrix metalloproteinase-9 (MMP-9), and connective tissue growth factor (CTGF) in aqueous humour to determine if these may represent alternative therapeutic targets.

METHODS

Aqueous humour samples were collected from patients who underwent routine cataract surgery. All patients were categorised into three main groups-PXF, uveitis, and control. The PXF group was further subcategorised into three grades based on the density of the exfoliative material observed on biomicroscopy, as well as the presence or absence of glaucoma. TIMP-1, MMP-9, and CTGF levels were measured using specific enzyme immunoassays (ELISA).

RESULTS

Eyes with PXF had significantly higher aqueous humour TIMP-1 concentration (n = 56, mean (SE), 9.76 (1.10) ng/ml) compared with controls (n = 112, 5.73 (0.43) ng/ml, p<0.01). Similarly, the CTGF level in PXF eyes (n = 36, 4.38 (0.65) ng/ml) was higher than controls (n = 29, 2.35 (0.46) ng/ml, p<0.05). Further, the CTGF concentration in the PXF glaucoma group is significantly higher compared with PXF eyes without glaucoma (6.03 (1.09) ng/ml v 2.73 (0.45) ng/ml, p<0.01). The MMP-9 levels were low and below detection limit in all PXF and control samples with no statistical difference between groups.

CONCLUSION

A raised TIMP-1 level and a low MMP-9 level in aqueous humour of PXF eyes may imply a downregulation in proteolytic activity. The increased CTGF concentration supports the proposed fibrotic pathology of PXF. Regulation of MMP/TIMP expression and anti-CTGF therapy may offer potential therapeutic avenues for controlling PXF associated ocular morbidity.