Protective effects of PARP1-inhibitory compound in dry age-related macular degeneration.

Poly (ADP-ribose) polymerase 1 (PARP1)-dependent cell death in the retinal pigment epithelium (RPE) is implicated in dry age-related macular degeneration (AMD). Although PARP1 inhibitors are available for treating dry AMD, their delivery route is not ideal for patients. The aim of this study was to test the efficacy of a novel PARP1-inhibitory compound (PIC) in vitro and in vivo. This study presents PIC, a novel small molecule, with superior efficacy to PARP1 inhibitors in the market. PIC demonstrated a distinctive inhibitory profile against PARP isotypes than the FDA-approved PARP1 inhibitors. PIC inhibited PARP1 activation at an IC50 of 0.41 ± 0.15 nM in an enzyme-based assay in vitro and at IC50 and EC50 in ARPE-19 cells of 0.11 ± 0.02 nM and 0.22 ± 0.02 nM, respectively, upon H2O2 insult. PIC also moderated mitochondrial fission and depolarization and maintained cellular energy levels under oxidative stress in ARPE-19 cells. Furthermore, PIC demonstrated good corneal penetration in a rat model, presenting PIC as a promising candidate for eye drop therapeutics for dry AMD. When PIC was administered as an eye drop formulation, RPE morphology was preserved, maintaining the thickness of the outer nuclear layers under sodium iodate (SI) treatment in rats. In SI-treated rabbits, eye drop administration of PIC also retained the structural and functional integrity when analyzed using funduscopy and electroretinogram. Collectively, our data portray PIC as an attractive treatment measure for dry AMD.

The lipid elongation enzyme ELOVL2 is a molecular regulator of aging in the retina.

Methylation of the regulatory region of the elongation of very-long-chain fatty acids-like 2 (ELOVL2) gene, an enzyme involved in elongation of long-chain polyunsaturated fatty acids, is one of the most robust biomarkers of human age, but the critical question of whether ELOVL2 plays a functional role in molecular aging has not been resolved. Here, we report that Elovl2 regulates age-associated functional and anatomical aging in vivo, focusing on mouse retina, with direct relevance to age-related eye diseases. We show that an age-related decrease in Elovl2 expression is associated with increased DNA methylation of its promoter. Reversal of Elovl2 promoter hypermethylation in vivo through intravitreal injection of 5-Aza-2'-deoxycytidine (5-Aza-dc) leads to increased Elovl2 expression and rescue of age-related decline in visual function. Mice carrying a point mutation C234W that disrupts Elovl2-specific enzymatic activity show electrophysiological characteristics of premature visual decline, as well as early appearance of autofluorescent deposits, well-established markers of aging in the mouse retina. Finally, we find deposits underneath the retinal pigment epithelium in Elovl2 mutant mice, containing components found in human drusen, a pathologic hallmark of age related macular degeneration. These findings indicate that ELOVL2 activity regulates aging in mouse retina, provide a molecular link between polyunsaturated fatty acids elongation and visual function, and suggest novel therapeutic strategies for the treatment of age-related eye diseases.

Understanding the complexity of the matrix metalloproteinase system and its relevance to age-related diseases: Age-related macular degeneration and Alzheimer's disease.

Extracellular matrices (ECMs) are maintained by tightly coupled processes of continuous synthesis and degradation. The degradative arm is mediated by a family of proteolytic enzymes called the matrix metalloproteinases (MMPs). These enzymes are released as latent proteins (pro-MMPs) and on activation are capable of degrading most components of an ECM. Activity of these enzymes is checked by the presence of tissue inhibitors of MMPs (TIMPs) and current opinion holds that the ratio of TIMPs/MMPs determines the relative rate of degradation. Thus, elevated ratios are thought to compromise degradation leading to the accumulation of abnormal ECM material, whilst diminished ratios are thought to lead to excessive ECM degradation (facilitating angiogenesis and the spread of cancer cells). Our recent work has shown this system to be far more complex. MMP species tend to undergo covalent modification leading to homo- and hetero-dimerization and aggregation resulting in the formation of very large macromolecular weight MMP complexes (LMMCs). In addition, the various MMP species also show a bound-free compartmentalisation. The net result of these changes is to reduce the availability of the latent forms of MMPs for the activation process. An assessment of the degradation potential of the MMP system in any tissue must therefore take into account the degree of sequestration of the latent MMP species, a protocol that has not previously been addressed. Taking into consideration the complexities already described, we will present an analysis of the MMP system in two common neurodegenerative disorders, namely age-related macular degeneration (AMD) and Alzheimer's disease (AD).

Correlation of axial length and myopic macular degeneration to levels of molecular factors in the aqueous.

To elucidate the molecular processes associated with the development of myopic macular degeneration (MMD), we measured the intraocular concentrations of molecular factors in emmetropic and myopic eyes. This is a retrospective clinic-based case-control study that included eyes undergoing routine cataract surgery whereby aqueous humour samples were obtained. We measured the concentrations of pigment epithelium derived factor(PEDF), matrix metalloproteinase 2(MMP-2), tissue inhibitor of metalloproteinase(TIMP-2), vascular endothelial growth factor isoform A(VEGF-A), interleukin 8(IL-8), interleukin 6(IL-6), C-reactive protein(CRP), angiopoietin 2(Ang2), and amphiregulin. 38 eyes (axial length (AL): 22.4-32.4 mm), including 12 highly myopic (HM) eyes (AL ≥ 26.5 mm) without MMD and 12 HM eyes with MMD but without neovascularization were included. Eyes with MMD were found to have significantly lower VEGF-A levels (p = 0.007) and higher MMP-2 levels (p = 0.02) than control eyes after adjusting for age and gender. MMP-2 levels correlated positively (r = 0.58, p = 0.002), while VEGF-A levels correlated negatively with longer axial length (r = -0.75, p < 0.001). Both the concentrations of VEGF-A (P = 0.25) and MMP-2 (P = 0.69) were not significantly associated with MMD after adjusting for AL. These findings suggest that the predominant mechanism underlying the development of non-neovascular MMD may be axial elongation, driven in part by MMP-2 related mechanisms.

Molecular Mechanisms of Complement System Proteins and Matrix Metalloproteinases in the Pathogenesis of Age-Related Macular Degeneration.

Age-related macular degeneration (AMD) is an eye disorder affecting predominantly the older people above the age of 50 years in which the macular region of the retina deteriorates, resulting in the loss of central vision. The key factors associated with the pathogenesis of AMD are age, smoking, dietary, and genetic risk factors. There are few associated and plausible genes involved in AMD pathogenesis. Common genetic variants (with a minor allele frequency of >5% in the population) near the complement genes explain 40-60% of the heritability of AMD. The complement system is a group of proteins that work together to destroy foreign invaders, trigger inflammation, and remove debris from cells and tissues. Genetic changes in and around several complement system genes, including the CFH, contribute to the formation of drusen and progression of AMD. Similarly, Matrix metalloproteinases (MMPs) that are normally involved in tissue remodeling also play a critical role in the pathogenesis of AMD. MMPs are involved in the degradation of cell debris and lipid deposits beneath retina but with age their functions get affected and result in the drusen formation, succeeding to macular degeneration. In this review, AMD pathology, existing knowledge about the normal and pathological role of complement system proteins and MMPs in the eye is reviewed. The scattered data of complement system proteins, MMPs, drusenogenesis, and lipofusogenesis have been gathered and discussed in detail. This might add new dimensions to the understanding of molecular mechanisms of AMD pathophysiology and might help in finding new therapeutic options for AMD.

Association analysis of genetic polymorphisms and expression levels of selected genes involved in extracellular matrix turnover and angiogenesis with the risk of age-related macular degeneration.

BACKGROUND: Age-related macular degeneration is a progressive eye disease affecting the macula and causing acute visual loss particularly in elder people. The aim of the study was an attempt to discern an influence of expression levels and functional genetic polymorphisms of selected genes related to the extracellular matrix turnover or neovascularization on age-related macular degeneration occurrence and progression. METHODS: We conducted a case-control study of 200 polish patients with recognized age-related macular degeneration (dry and wet) and compared the results with those obtained from matched 100 healthy control subjects. TaqMan Genotyping Assays were employed to examine the following single nucleotide polymorphisms: matrix metalloproteinase (MMP)-2 -735C/T, MMP-7 -181A/G, MMP-9 -1702T/A, and -1562C/T; tissue inhibitors of metalloproteinase (TIMP)-2 -418G/C; vascular endothelial growth factor (VEGF) +405 G/C and +936 C/T, VEGFR-2 +1719 T/A and -271 G/A. Real-time polymerase chain reaction was assessed to determine the mRNA quantity. Serum levels of proteins were measured using enzyme-linked immunosorbent assay. RESULTS: The single nucleotide polymorphism genotyping showed that TT genotype for MMP-9 -1702T/A and CC genotype for VEGF +936C/T increase markedly the risk of age-related macular degeneration but do not influence on its progression. Additionally, the possible protective effect of CC genetic variant in MMP-9 -1562C/T polymorphism against progression of age-related macular degeneration was observed. We also found significant differences in systemic expression levels of MMP-2, -7, -9, TIMP-2, vascular endothelial growth factor, VEGFR-2, and pigment epithelium-derived factor between studied group. The research demonstrated evident differences in serum levels of MMP-2, -7, -9, TIMP-2, vascular endothelial growth factor, and pigment epithelium-derived factor between wet and dry age-related macular degeneration patients. CONCLUSIONS: We can conclude that disturbances in angiogenic homeostasis and processes of extracellular matrix turnover occurring in age-related macular degeneration-affected ocular tissues may be reflected in changes in systemic expression levels of the investigated genes.

The Role of c-Jun N-Terminal Kinase (JNK) in Retinal Degeneration and Vision Loss.

c-Jun N-terminal kinase (JNK), a member of stress-induced mitogen-activated protein (MAP) kinase family, has been shown to modulate a variety of biological processes associated with neurodegenerative pathology of the retina. In particular, various retinal cell culture and animal models related to glaucoma, age-related macular degeneration (AMD), and retinitis pigmentosa indicate that JNK signaling may contribute to disease pathogenesis. This mini-review discusses the impact of JNK signaling in retinal disease, with a focus on retinal ganglion cells (RGCs), photoreceptor cells, retinal pigment epithelial (RPE) cells, and animal studies, with particular attention to modulation of JNK signaling as a potential therapeutic target for the treatment of retinal disease.

Sodium Iodate-Induced Mouse Model of Age-Related Macular Degeneration Displayed Altered Expression Patterns of Sumoylation Enzymes E1, E2 and E3.

PURPOSE: Protein sumoylation is a highly dynamic and reversible post-translational modification, involving covalently conjugation of the small ubiquitin-like modifier (SUMO) to the lysine residue of the target protein. Similar to ubiquitination, sumoylation is catalyzed by E1, E2 and several E3 ligases. However, sumoylation usually does not cause protein degradation but alter the target function through diverse mechanisms. Increasing evidences have shown that sumoylation plays pivotal roles in the pathogenesis of human diseases, including neuron degeneration, cancer and heart disease, etc. We and others have shown that sumoylation is critically implicated in mouse eye development. However, the expression of sumoylation machinery has not been characterized in normal and pathogenic retina. Worldwide, age-related macular degeneration (AMD) is the leading cause of irreversible blindness in aged person. In the present study, we investigated the expression of the major sumoylation enzymes in normal mice and sodium iodateinduced AMD mouse model. METHODS: Four-week-old C57BL/6J mice were used in our experiment. A sterile 1% NaIO3 solution was freshly prepared in PBS from solid NaIO3. Experimental mice were injected with 70 mg/kg NaIO3, and similar volumes of PBS as control. Eyes were enucleated and immersion in FAA fixation overnight and processed for eye cross-sections. After fixation, cross sections eyes were dehydrated, embedded in paraffin, and 6 mm transverse sections were cut using the rotary microtome. Then paraffin sections were stained with hematoxylin and eosin (H&E), and mouse retinal thickness was observed to assess the histopathologic changes. RESULTS: Significantly declined RNA levels of E1, E2 and E3 ligase PIAS1 in NaIO3-injected mouse RPE one day-post treatment. Consistently, the protein level of PIAS1 was also decreased at this time point. At the late stage of treatment (three days post-injection), significantly reduced expression of E1 enzyme SAE1/UBA2 was detected in NaIO3-injected mouse retinas. In the contrary, dramatically increased E3 ligase RanBP2 was found in the injected-retinas. CONCLUSION: Together, our results demonstrated for the first time the dynamic expression of sumoylation pathway enzymes during the progression of retina degeneration induced by oxidative stress. Dynamic expression of E1, E2 and E3 enzymes were found during the time course of RPE and retina degeneration, which revealed the potential regulatory roles of sumoylation in AMD pathogenesis.

PTEN Reduced UVB-Mediated Apoptosis in Retinal Pigment Epithelium Cells.

Age-related macular degeneration (AMD) is a leading cause of blindness and progressive loss of central vision in the elderly population. The important factor of AMD pathogenesis is the degeneration of retinal pigment epithelial (RPE) cells by oxidative stress. Inactivation of PTEN can disrupt intercellular adhesion in the RPE cells, but the mechanism of oxidative stress is less known. Here we presented evidence that UVB-mediated oxidative stress induced apoptosis in ARPE-19 cells. Downregulation of the expression of PTEN in UVB-irradiative RPE cells triggered DNA damage and increased the level of UVB-induced apoptosis by activating p53-dependent pathway. However, overexpression of PTEN increased cell survival by suppressing p-H2A in response to DNA damage and apoptosis. When using Pifithrin-α (one of p53 inhibitors), the level of p53-dependent apoptosis was significantly lower than untreated, which suggested that p53 was possibly involved in PTEN-dependent apoptosis. Thus, it elucidated the molecular mechanisms of UVB-induced damage in RPE cells and may offer an alternative therapeutic target in dry AMD.

Amyloid ß induces NLRP3 inflammasome activation in retinal pigment epithelial cells via NADPH oxidase- and mitochondria-dependent ROS production.

Amyloid ß (Aß)-induced chronic inflammation is believed to be a key pathogenic process in early-stage age-related macular degeneration (AMD). Nucleotide oligomerization domain (NOD)-like receptor family, pyrin domain containing 3 (NLRP3) inflammasome activation triggered by Aß is responsible for retinal pigment epithelium (RPE) dysfunction in the onset of AMD; however, the detailed molecular mechanism remains unclear. In this study, we investigated the involvement of NADPH oxidase- and mitochondria-derived reactive oxygen species (ROS) in the process of Aß1-40 -induced NLRP3 inflammasome activation in LPS-primed ARPE-19 cells. The results showed that Aß1-40 could induce excessive ROS generation, MAPK/NF-κB signaling activation and subsequently NLRP3 inflammasome activation in LPS-primed ARPE-19 cells. Furthermore, the inductive effect of Aß1-40 on NLRP3 inflammasome activation was mediated in a manner dependent on NADPH oxidase- and mitochondria-derived ROS. Our findings may provide a novel insight into the molecular mechanism by which Aß contributes to the early-stage AMD.

A Non-Canonical Role for ß-Secretase in the Retina.

It has long been established that ß-Secretase (BACE) plays a critical role in the formation of amyloid plaques in Alzheimer's Disease patients, but it is only recently that the importance of ß-secretases in retinal pathophysiology has been recognized. BACE expression is elevated in response to stress, and downregulation results in lysosomal abnormalities and mitochondrial changes. Inhibition of BACE can lead to reduced retinal function, retinal thinning, lipofuscin accumulation and vascular dysfunction in mice. Furthermore, BACE inhibition accelerates choroidal neovascularization (CNV) in mice. We propose that BACE plays an important role in retinal homeostasis and that BACE upregulation in response to stress is a protective measure.

Synonymous variants in HTRA1 implicated in AMD susceptibility impair its capacity to regulate TGF-ß signaling.

High-temperature requirement A1 (HTRA1) is a secreted serine protease reported to play a role in the development of several cancers and neurodegenerative diseases. Still, the mechanism underlying the disease processes largely remains undetermined. In age-related macular degeneration (AMD), a common cause of vision impairment and blindness in industrialized societies, two synonymous polymorphisms (rs1049331:C>T, and rs2293870:G>T) in exon 1 of the HTRA1 gene were associated with a high risk to develop disease. Here, we show that the two polymorphisms result in a protein with altered thermophoretic properties upon heat-induced unfolding, trypsin accessibility and secretion behavior, suggesting unique structural features of the AMD-risk-associated HTRA1 protein. Applying MicroScale Thermophoresis and protease digestion analysis, we demonstrate direct binding and proteolysis of transforming growth factor ß1 (TGF-ß1) by normal HTRA1 but not the AMD-risk-associated isoform. As a consequence, both HTRA1 isoforms strongly differed in their ability to control TGF-ß mediated signaling, as revealed by reporter assays targeting the TGF-ß1-induced serpin peptidase inhibitor (SERPINE1, alias PAI-1) promoter. In addition, structurally altered HTRA1 led to an impaired autocrine TGF-ß signaling in microglia, as measured by a strong down-regulation of downstream effectors of the TGF-ß cascade such as phosphorylated SMAD2 and PAI-1 expression. Taken together, our findings demonstrate the effects of two synonymous HTRA1 variants on protein structure and protein interaction with TGF-ß1. As a consequence, this leads to an impairment of TGF-ß signaling and microglial regulation. Functional implications of the altered properties on AMD pathogenesis remain to be clarified.

The Role of Peptidyl Prolyl Isomerases in Aging and Vascular Diseases.

Peptidyl prolyl isomerases (PPIases) are proteins belonging to the immunophilin family and are characterised by their cis-trans isomerization activity at the X-Pro peptide bond, in addition to their tetratricopeptide repeat (TPR) domain, important for interaction with the molecular chaperone, Hsp90. Due to this unique structure these proteins are able to facilitate protein-protein interactions which can impact significantly on a range of cellular processes such as cell signalling, differentiation, cell cycle progression, metabolic activity and apoptosis. Malfunction and/or dysregulation of most members of this class of proteins promotes cellular damage and tissue/organ failure, predisposing to ageing and age-related diseases. Many individual genes within the PPIase family are associated with several age-related diseases including cardiovascular diseases (CVDs), atherosclerosis, type II diabetes mellitus (T2D), chronic kidney disease (CDK), neurodegeneration, cancer and age-related macular degeneration (AMD), in addition to the ageing process itself. This review will focus on the different roles of PPIases, and their therapeutic/ biomarker potential in these age-related vascular diseases.

Triamcinolone regulated apopto-phagocytic gene expression patterns in the clearance of dying retinal pigment epithelial cells. A key role of Mertk in the enhanced phagocytosis.

BACKGROUND: The apopto-phagocytic gene expression patterns during clearance of dying cells in the retina and the effect of triamcinolone (TC) upon these processes have relevance to development of age-related macular degeneration (AMD). METHODS: ARPE-19 cells and primary human retinal pigment epithelium (hRPE) were induced to undergo cell death by anoikis and the clearance of these cells by living hRPE/ARPE-19 or human monocyte-derived macrophages (HMDMs) in the presence or absence of TC was quantified by flow cytometry. TaqMan low-density gene expression array determining known markers of phagocytosis and loss-of-function studies on selected apopto-phagocytic genes was carried out in HMDM engulfing anoikic cells. RESULTS: The glucocorticoid TC had a profound phagocytosis-enhancing effect on HMDM engulfing anoikic ARPE-19 or hRPE cells, causing a selective upregulation of the Mer tyrosine kinase (MERTK) receptor, while decreasing the expression of the AXL receptor tyrosine kinase and thrombospondin-1 (THSB-1). The key role of the MERTK could be demonstrated in HMDM engulfing dying cells using gene silencing as well as blocking antibodies. Similar pathways were found upregulated in living ARPE-19 engulfing anoikic ARPE-19 cells. Gas6 treatment enhanced phagocytosis in TC-treated HMDMs. CONCLUSIONS: Specific agonists of the Mertk receptor may have a potential role as phagocytosis enhancers in the retina and serve as future targets for AMD therapy. GENERAL SIGNIFICANCE: The use of Gas6 as enhancer of retinal phagocytosis via the MerTK receptor, alone or in combination with other specific ligands of the tyrosine kinase receptors' family may have a potential role in AMD therapy.

The Role of Matrix Metalloproteinases Polymorphisms in Age-Related Macular Degeneration.

BACKGROUND: Matrix metalloproteinases (MMP) are responsible for the degradation of extracellular matrix components and play an important role in the physiological and pathological remodeling of tissues. PURPOSE: To assess the impact of MMP-2 Rs2285053 (C->T), MMP-3 Rs3025039 (5A->6A), and MMP-9 Rs3918242 (C->T) single nucleotide polymorphism on the development of early age-related macular degeneration (AMD). METHODS: The study group comprised 148 patients with AMD, and the control group enrolled 526 randomly selected persons. The genotyping of MMP-3 Rs3025039, MMP-2 Rs2285053, and MMP-9 Rs3918242 was performed by using the real-time PCR method. RESULTS: The frequency of the MMP-2 (-735) C/T and MMP-3 (-1171) 5A/6A genotypes did not differ significantly between the patients with AMD and the control group, while the MMP-9 (-1562) C/C genotype was more frequently detected in patients with AMD than the control group (73.7% vs. 64.6%, p=0.048). Logistic regression analysis showed that the MMP-9 (-1562) C/C genotype increased the likelihood of developing early AMD (OR=1.51, 95% CI: 1.01-2.21; p=0.046). After the subdivision into the groups by age, a significant difference only in the frequency of the MMP-9 (-1562) C/C genotype was found comparing the AMD patients and the control group younger than 65 years (79.7% vs. 66.4%, p=0.039). CONCLUSIONS: Only MMP-9 Rs3918242 (C->T) single nucleotide polymorphism was found to play a significant role in the development of AMD, and the effect was more pronounced at the age of less than 65 years.

Age-related macular degeneration and changes in the extracellular matrix.

Age-related macular degeneration (AMD) is the leading cause of permanent, irreversible, central blindness (scotoma in the central visual field that makes reading and writing impossible, stereoscopic vision, recognition of colors and details) in patients over the age of 50 years in European and North America countries, and an important role is attributed to disorders in the regulation of the extracellular matrix (ECM). The main aim of this article is to present the crucial processes that occur on the level of Bruch's membrane, with special consideration of the metalloproteinase substrates, metalloproteinase, and tissue inhibitor of metalloproteinase (TIMP). A comprehensive review of the literature was performed through MEDLINE and PubMed searches, covering the years 2005-2012, using the following keywords: AMD, extracellular matrix, metalloproteinases, tissue inhibitors of metalloproteinases, Bruch's membrane, collagen, elastin. In the pathogenesis of AMD, a significant role is played by collagen type I and type IV; elastin; fibulin-3, -5, and -6; matrix metalloproteinase (MMP)-2, MMP-9, MMP-14, and MMP-1; and TIMP-3. Other important mechanisms include: ARMS2 and HTR1 proteins, the complement system, the urokinase plasminogen activator system, and pro-renin receptor activation. Continuous rebuilding of the extracellular matrix occurs in both early and advanced AMD, simultaneously with the dysfunction of retinal pigment epithelium (RPE) cells and endothelial cells. The pathological degradation or accumulation of ECM structural components are caused by impairment or hyperactivity of specific MMPs/TIMPs complexes, and is also endangered by the influence of other mechanisms connected with both genetic and environmental factors.

Increased 26S proteasome non-ATPase regulatory subunit 1 in the aqueous humor of patients with age-related macular degeneration.

Age-related macular degeneration (AMD) is the leading cause of blindness in the world. Evidence indicates that the suppression of the ubiquitin-proteasome system (UPS) contributes to the accumulation of toxic proteins and inflammation in retinal pigment epithelium (RPE), the functional abnormalities and/or the degeneration of which are believed to be the initiators and major pathologies of AMD. To identify new protein associations with the altered UPS in AMD, we used LC-ESI-MS/MS to perform a proteomic analysis of the aqueous humor (AH) of AMD patients and matched control subjects. Six UPS-related proteins were present in the AH of the patients and control subjects. Four of the proteins, including 26S proteasome non-ATPase regulatory subunit 1 (Rpn2), were increased in patients, according to semi-quantitative proteomic profiling. An LC-MRM assay revealed a significant increase of Rpn2 in 15 AMD patients compared to the control subjects, suggesting that this protein could be a biomarker for AMD.

Superoxide dismutase1 levels in North Indian population with age-related macular degeneration.

AIM: The aim of the study was to estimate the levels of superoxide dismutase1 (SOD1) in patients of age-related macular degeneration (AMD) and examine the role of oxidative stress, smoking, hypertension, and other factors involved in the pathogenesis of AMD. METHODS: 115 AMD patients and 61 healthy controls were recruited for this study. Serum SOD1 levels were determined by ELISA and were correlated to various risk factors. Logistic regression model of authenticity, by considering SOD1 as independent variable, has been developed along with ROC curve. RESULTS: The SOD1 levels were significantly higher in AMD patients as compared to those of the controls. The difference was not significant for wet and dry AMD. However, the difference was significant between wet AMD subtypes. Nonsignificance of the Hosmer-Lemeshow goodness of fit statistic (χ(2) = 10.516, df = 8, P = 0.231) indicates the appropriateness of logistic regression model to predict AMD. CONCLUSION: Oxidative stress in AMD patients may mount compensatory response resulting in increased levels of SOD1 in AMD patients. To predict the risk of AMD on the basis of SOD1, a logistic regression model shows authenticity of 78%, and area under the ROC curve (0.827, P = .0001) with less standard error of 0.033 coupled with 95% confidence interval of 0.762-0.891 further validates the model.

Role of antioxidant enzymes and small molecular weight antioxidants in the pathogenesis of age-related macular degeneration (AMD).

Cells in aerobic condition are constantly exposed to reactive oxygen species (ROS), which may induce damage to biomolecules, including proteins, nucleic acids and lipids. In normal circumstances, the amount of ROS is counterbalanced by cellular antioxidant defence, with its main components-antioxidant enzymes, DNA repair and small molecular weight antioxidants. An imbalance between the production and neutralization of ROS by antioxidant defence is associated with oxidative stress, which plays an important role in the pathogenesis of many age-related and degenerative diseases, including age-related macular degeneration (AMD), affecting the macula-the central part of the retina. The retina is especially prone to oxidative stress due to high oxygen pressure and exposure to UV and blue light promoting ROS generation. Because oxidative stress has an established role in AMD pathogenesis, proper functioning of antioxidant defence may be crucial for the occurrence and progression of this disease. Antioxidant enzymes play a major role in ROS scavenging and changes of their expression or/and activity are reported to be associated with AMD. Therefore, the enzymes in the retina along with their genes may constitute a perspective target in AMD prevention and therapy.

Serum levels of matrix metalloproteinase 2 and matrix metalloproteinase 9 elevated in polypoidal choroidal vasculopathy but not in age-related macular degeneration.

PURPOSE: Age-related macular degeneration (AMD) and polypoidal choroidal vasculopathy (PCV) are the leading causes of vision loss in the elderly Asian population. Previous studies have confirmed that abnormal extracellular matrix (ECM) metabolism plays an important role in the pathogenesis of AMD and PCV. However, the dynamic metabolism of the ECM is closely regulated by matrix metalloproteinases (MMPs) and tissue metalloproteinase inhibitors (TIMPs). Whether MMPs and TIMPs participate in the pathogenesis of AMD and PCV remains unclear. The aim of this study was to investigate the correlation between circulating MMP and TIMP levels and AMD and PCV. METHODS: The serum levels of MMPs (MMP1, MMP2, MMP3, and MMP9) and TIMPs (TIMP1 and TIMP3) were quantified using enzyme-linked immunosorbent assays in four groups of subjects (n=342): early AMD (group 1, n=75), neovascular AMD (group 2, n=89), PCV (group 3, n=98), and age- and gender-matched controls (group 4, n=80). RESULTS: The mean concentrations of the two gelatinases, MMP2 and MMP9, in the PCV group were significantly higher than that of the control (p=0.001, p<0.001, respectively), early AMD (both p<0.001), and neovascular AMD (p=0.005, p=0.001, respectively) groups. Moreover, the serum MMP2 concentration was positively correlated with the serum MMP9 concentration in the PCV group (r=0.822, p<0.001). However, the mean concentrations of MMP2 and MMP9 in the early AMD and neovascular AMD groups were not significantly different from that of the control group (p>0.05). The mean serum levels of MMP1, MMP3, TIMP1, and TIMP3 were not significantly different among the four groups. CONCLUSIONS: This pilot study first reveals a link between increased levels of circulating gelatinases (MMP2 and MMP9) and PCV but not AMD, which may provide a biologically relevant marker of ECM metabolism in patients with PCV. This finding suggests that the two disorders may have different molecular mechanisms.