elastin and Macular-Degeneration

The extracellular matrix (ECM) and its turnover play a crucial role in the pathogenesis of several inflammatory diseases, including age-related macular degeneration (AMD). Elastin, a critical protein component of the ECM, not only provides structural and mechanical support to tissues, but also mediates several intracellular and extracellular molecular signaling pathways. Abnormal turnover of elastin has pathological implications. In the eye elastin is a major structural component of Bruch's membrane (BrM), a critical ECM structure separating the retinal pigment epithelium (RPE) from the choriocapillaris. Reduced integrity of macular BrM elastin, increased serum levels of elastin-derived peptides (EDPs), and elevated elastin antibodies have been reported in AMD. Existing reports suggest that elastases, the elastin-degrading enzymes secreted by RPE, infiltrating macrophages or neutrophils could be involved in BrM elastin degradation, thus contributing to AMD pathogenesis. EDPs derived from elastin degradation can increase inflammatory and angiogenic responses in tissues, and the elastin antibodies are shown to play roles in immune cell activity and complement activation. This review summarizes our current understanding on the elastases/elastin fragments-mediated mechanisms of AMD pathogenesis.

Topics: Bruch Membrane; Choroid; Elastin; Humans; Macular Degeneration; Peptides; Retinal Pigment Epithelium

Age-related macular degeneration (AMD) etiology is unknown, but its association to atherosclerotic vascular disease (ASVD) has been observed. Since elastin plays an important role in the atherosclerotic process, to understand ASVD and AMD's relationship we examined retinal elastin existence, elastin amount and vessel properties among normal subjects, mild AMD patients, moderate-to severe AMD patients, and ASVD patients (n = 20). One eye per donor was assigned to enzyme-linked immunosorbent assay for quantifying the retinal elastin amount. The rest were assigned to mechanical test for examining the retinal vessel properties. Additionally, two normal human and two porcine eyes were acquired in immunohistochemistry for locating the retinal elastin. We found that elastin presented in the human and porcine retinal vessels at the basement membranes. 3.73 ± 0.55% of the normal retinal tissues were elastin. Elastin decrease, tissue-weight increase, and vessel hardening and in elasticity (p<0.05) were observed in the retina of patients with ASVD and only moderate-to-severe (i.e., not mild) AMD. Most moderate-to-severe AMD patients also happened to have ASVD. The results suggest that ASVD is unlikely the cause of AMD, but it is perhaps a factor that aggravates the condition through mechanism associated with retinal vessel abnormality.

Topics: Aged; Aged, 80 and over; Atherosclerosis; Elastin; Enzyme-Linked Immunosorbent Assay; Eye Proteins; Female; Humans; Macular Degeneration; Male; Middle Aged; Retina

Age-related macular degeneration (AMD) is associated with an overactive complement system and an increase in circulating antibodies. Our search for potential neoantigens that can trigger complement activation in disease has led us to investigate elastin. A loss of the elastin layer (EL) of Bruch's membrane (BrM) has been reported in aging and AMD together with an increase of serum elastin-derived peptides and α-elastin antibodies. In the mouse model of cigarette smoke exposure (CSE), damage in BrM, loss of the EL, and vision loss are dependent on complement activation. We have examined the hypothesis that CSE generates immunogenic elastin neoepitopes that trigger an increase in α-elastin IgG and IgM antibodies, which can then bind to the neoepitopes in the target cells or membranes, triggering complement activation. Specifically, we showed that immunization with elastin peptide oxidatively modified by cigarette smoke (ox-elastin) exacerbated ocular pathology and vision loss in CSE mice. In contrast, mice receiving peptide immunotherapy (PIT) with ox-elastin did not lose vision over the smoking period and exhibited a more preserved BrM. Immunization and PIT correlated with humoral immunity and complement activation and IgG/IgM deposition in the RPE/BrM/choroid. Finally, PIT modulated immune markers IFNγ and IL-4. The data further support the hypothesis that complement activation, triggered by immune complex formation in target tissues, plays a role in ocular damage in the CSE model. As PIT with ox-elastin peptides reduces damage, we discuss the possibility that AMD progression might be preventable.

Topics: Animals; Bruch Membrane; Elastin; Immunization; Immunoglobulin G; Immunoglobulin M; Macular Degeneration; Mice

Age-related macular degeneration (AMD), the leading cause of blindness in western populations, is associated with an overactive complement system, and an increase in circulating antibodies against certain epitopes, including elastin. As loss of the elastin layer of Bruch's membrane (BrM) has been reported in aging and AMD, we previously showed that immunization with elastin peptide oxidatively modified by cigarette smoke (ox-elastin), exacerbated ocular pathology in the smoke-induced ocular pathology (SIOP) model. Here we asked whether ox-elastin peptide-based immunotherapy (PIT) ameliorates damage.. Elimination of Fcγ receptors, preventing antigen/antibody-dependent cytotoxicity, protected against SIOP. Mice receiving PIT with low dose ox-elastin (LD-PIT) exhibited reduced humoral immunity, reduced complement activation and IgG/IgM deposition in the RPE/choroid, and largely a preserved BrM. While there is no direct evidence of ox-elastin pathogenicity, LD-PIT reduced IFNγ and increased IL-4 within RPE/choroid. High dose PIT was not protective.. These data further support ox-elastin role in ocular damage in part via elastin-specific antibodies, and support the corollary that PIT with ox-elastin attenuates ocular pathology. Overall, damage is associated with complement activation, antibody-dependent cell-mediated cytotoxicity, and altered cytokine signature.

Topics: Animals; Cigarette Smoking; Complement Activation; Disease Models, Animal; Elastin; Immunotherapy; Macular Degeneration; Mice; Mice, Inbred C57BL; Microscopy, Electron; Peptides; Receptors, IgG; Retinal Pigment Epithelium; Smoke

Humanin (HN) is a hydrophobic 24-amino acid peptide derived from mitochondrial DNA that modulates cellular responses to oxidative stress and protects human retinal pigment epithelium (RPE) cells from apoptosis. To solubilize HN, this report describes two genetically-encoded fusions between HN and elastin-like polypeptides (ELP). ELPs provide steric stabilization and/or thermo-responsive phase separation. Fusions were designed to either remain soluble or phase separate at the physiological temperature of the retina. Interestingly, the soluble fusion assembles stable colloids with a hydrodynamic radius of 39.1 nm at 37°C. As intended, the thermo-responsive fusion forms large coacervates (>1,000 nm) at 37°C. Both fusions bind human RPE cells and protect against oxidative stress-induction of apoptosis (TUNEL, caspase-3 activation). Their activity is mediated through STAT3; furthermore, STAT3 inhibition eliminates their protection. These findings suggest that HN polypeptides may facilitate cellular delivery of biodegradable nanoparticles with potential protection against age-related diseases, including macular degeneration.

Topics: Apoptosis; Cells, Cultured; Elastin; Epithelial Cells; Humans; Intracellular Signaling Peptides and Proteins; Macular Degeneration; Nanoparticles; Oxidative Stress; Peptides; Retinal Pigment Epithelium

Age-related macular degeneration (AMD) is the leading cause of severe and irreversible central vision loss, and the primary site of AMD pathology is the retinal pigment epithelium (RPE). Geographic atrophy (GA) is an advanced form of AMD characterized by extensive RPE cell loss, subsequent degeneration of photoreceptors, and thinning of retina. This report describes the protective potential of a peptide derived from the αB crystallin protein using a sodium iodate (NaIO

Topics: alpha-Crystallin B Chain; Animals; Disease Models, Animal; Elastin; Eye; Intravitreal Injections; Iodates; Macular Degeneration; Mice; Neuroprotection; Neuroprotective Agents; Peptides

To compare the association of elastin (ELN) gene variants between two different angiographic phenotypes of polypoidal choroidal vasculopathy (PCV).. We included 411 treatment-naïve PCV patients and 350 controls in the present study. PCV was classified into two phenotypes (152 Type 1 and 259 Type 2) according to the presence or absence of feeding vessels found in indocyanine-green angiography. Single nucleotide polymorphisms (SNPs) in the ELN region including rs868005, rs884843, rs2301995, rs13239907 and rs2856728 were genotyped using TaqMan Genotyping Assays.. In the allelic association analyses, rs868005 showed the strongest association with Type 2 PCV (allelic odds ratio 1.56; p = 7.4x10(-6)), while no SNP was significantly associated with Type 1 PCV. Genotype association analyses revealed the significant association of rs868005 with Type 2 PCV in log additive model and predominant model (odds ratio 1.75; p = 1.5x10(-6) and odds ratio 1.60; p = 0.0044, respectively), but not with Type 1 PCV. These findings were further corroborated by another control group in the literature.. There may be significantly different associations in genetic variants of elastin between two angiographic phenotypes of PCV.

Topics: Aged; Aged, 80 and over; Alleles; Case-Control Studies; Choroidal Neovascularization; Elastin; Female; Fluorescein Angiography; Genetic Variation; Genotype; Humans; Linkage Disequilibrium; Macular Degeneration; Male; Middle Aged; Phenotype; Polymorphism, Single Nucleotide

To investigate the association of the rs2301995 haplotype-tagging single nucleotide polymorphism (htSNP) in the elastin gene (ELN) with polypoidal choroidal vasculopathy (PCV) in European-American patients.. Association analysis of allele and genotype frequencies, determined by TaqMan assays, was performed for the rs2301995 haplotype-tagging single nucleotide polymorphism (htSNP) in the ELN locus in fifty-six patients with PCV, 368 patients with advanced age-related macular degeneration (AMD) and 368 age- and ethnically-matched unaffected controls.. The ELN rs2301995 SNP was not statistically significantly associated with the PCV phenotype (P = 0.9). The frequency of the minor allele of the rs2301995 SNP was practically identical in the PCV, AMD and control groups (6.3% vs. 5.4% vs. 7.1%).. The PCV phenotype in European-American patients is not associated with rs2301995 SNP in the ELN locus.

Topics: Aged; Choroid; Choroid Diseases; Elastin; Genotype; Humans; Macular Degeneration; Peripheral Vascular Diseases; Polymorphism, Single Nucleotide; White People

The aim of this study is to investigate the use of elastin-like recombinamers (ELRs) as a substrate that can maintain the growth, phenotype, and functional characteristics of retinal pigment epithelial (RPE) cells efficiently and as a suitable carrier for the transplantation of autologous RPE cells for treatment of age-related macular degeneration (AMD). ELR films containing a bioactive sequence, RGD (ELR-RGD), and one with no specific sequence (ELR-IK) as control, were obtained by solvent-casting onto glass and subsequent cross-linking. ARPE19 cells were seeded on sterilized ELR films as well as on the control surfaces. Cells were analysed after 4, 24, 72, and 120 h to study cell adhesion, proliferation, cell viability, morphology, and specificity by staining with Trypan blue, DAPI, Rhodamin-Phalloidin and RPE65, ZO-1 antibodies and observing under fluorescence as well as electron microscope. ARPE19 cells seeded on both ELR films and controls were 100% viable and maintained their morphology and set of characteristics at the different time points studied. Cell proliferation on ELR-RGD was significantly higher than that found on ELR-IK at all time points, although it was less than the growth rate on polystyrene. ARPE19 cells grow well on ELR-RGD maintaining their phenotype. These results should be extended to further studies with fresh human RPE cells and in vivo studies to determine whether this ELR-RGD matrix could be used as a Bruch's membrane prosthesis and carrier for transplantation of RPE cells in patients suffering with AMD.

Topics: Amino Acid Sequence; Carrier Proteins; Cell Adhesion; Cell Line; Cell Proliferation; cis-trans-Isomerases; Elastin; Epithelial Cells; Eye Proteins; Gene Expression; Humans; Macular Degeneration; Molecular Sequence Data; Oligopeptides; Regeneration; Retinal Pigment Epithelium; Tissue Scaffolds

To see if there is an association in Japanese between elastin gene (ELN) polymorphisms and neovascular age-related macular degeneration (AMD) or its subtypes, typical AMD (tAMD) and polypoidal choroidal vasculopathy (PCV).. The authors genotyped five single nucleotide polymorphisms (SNPs), rs2301995, rs2856728, rs868005, rs884843, and rs13239907, at Kyoto University and Saitama Medical University. A case-control study was performed on 1296 patients with AMD and 478 controls.. A statistically significant association was detected between the rs2301995 SNP and AMD (P = 0.018). Furthermore, subtype analysis revealed a significant association of rs2301995 with tAMD (P = 0.0018), but not with PCV. The genotype distribution of rs2301995 also differed significantly between tAMD and PCV (P = 0.00030). The trend in genotype distribution of rs2301995 was similar between the Kyoto and the Saitama studies. The A allele frequency was higher in tAMD, whereas it was similar in PCV and in controls, which is opposite to that reported in a previous study that the A allele frequency is higher in PCV, whereas it is similar in tAMD and in controls. Haplotype analysis also showed that the ELN polymorphism is significantly associated with tAMD (P = 0.0055), but not with PCV.. ELN is associated with AMD in Japanese. Furthermore, the findings suggest that ELN is a susceptibility gene for tAMD but not for PCV, which is opposite to that reported in a previous study that ELN is the susceptibility gene for PCV but not for tAMD.

Topics: Aged; Aged, 80 and over; Asian People; Case-Control Studies; Choroidal Neovascularization; Elastin; Female; Genetic Predisposition to Disease; Haplotypes; Humans; Japan; Macular Degeneration; Male; Middle Aged; Polymorphism, Single Nucleotide

Age-related macular degeneration (AMD) is thought to be a polygenetic disease. It is divided into three subtypes; neovascular AMD (nAMD), polypoidal choroidal vasculopathy, and retinal angiomatous proliferation (RAP). These subtypes are thought to have different pathophysiological and genetic backgrounds. We aimed to investigate the relationships between single nucleotide polymorphisms (SNPs) in candidate genes and subtypes of AMD in the Japanese population.. We genotyped 685 AMD patients and 277 controls for four SNPs of the selected candidate genes: rs800292 in complement factor H, rs10490924 in age-related maculopathy susceptibility 2 (ARMS2), rs2301995 in elastin (ELN), and rs1801133 in methylenetetrahydrofolate reductase (MTHFR). Case-control studies were performed using these AMD subtypes. Logistic regression analysis was performed using a history of hypertension, diabetes mellitus, and smoking as cardiovascular risks.. The genotype-dominant or recessive distribution of all four SNPs differed significantly between the controls and the AMD patients. In the subtype analysis, there were significant differences between the controls and the AMD patients in genotype distributions. This was true for all AMD subtype analyses of both rs800292 (complement factor H) and rs10490924 (ARMS2). Logistic regression analysis indicated the TT genotype of the ARMS2 gene to be significantly more common in RAP patients (p=1.54×10(-13), odds ratio: 22.18). In contrast, there were significant differences in the genotype distribution between the controls and nAMD patients only for rs2301995 (ELN, p=0.022) and rs1801133 (MTHFR, p=2.50×10(-3)).. Our results indicate that SNPs of the ARMS2 gene may serve as strong genetic markers of RAP, and that SNPs of the ELN and MTHFR genes are potential genetic markers for nAMD.

Topics: Aged; Aged, 80 and over; Case-Control Studies; Complement Factor H; Elastin; Female; Gene Frequency; Genetic Association Studies; Genetic Markers; Genetic Predisposition to Disease; Genotype; Humans; Japan; Macular Degeneration; Male; Methylenetetrahydrofolate Reductase (NADPH2); Middle Aged; Odds Ratio; Phenotype; Polymorphism, Single Nucleotide; Proteins; Risk Factors

Endothelial cell (EC) migration is a key event in angiogenesis, and is likely to play an important role in choroidal neovascularization in age-related macular degeneration (AMD). Altered elastin metabolism has been described in AMD, and the present study sought to determine the effects of elastin-derived peptides (EDPs) on choroidal EC migration and proliferation.. Migration of the chorioretinal EC line Rf/6a and a primary culture of human choroidal ECs through polycarbonate membrane inserts was quantified in the presence of elastin bioactive hexapeptides (BPs), EDPs, bovine serum albumin (BSA), or balanced salt solution. Proliferation assays and in vitro wound closure experiments were also performed in the presence of elastin fragments or balanced salt solution (control). Elastin overlay experiments were performed on sections of human eyes.. For both Rf/6a and human primary choroidal ECs exposed to EDPs or BPs, the number of ECs that migrated through the polycarbonate membrane was significantly higher than ECs exposed to balanced salt solution alone or to BSA (P < 0.05) in all experiments. In contrast, the rate of EC proliferation did not significantly change in comparison to controls. Elastin binding sites were identified on choroidal ECs in human eyes.. Elastin fragments increase choroidal EC migration, whereas they do not appear to increase or decrease EC proliferation. Local or systemic abnormalities in elastin physiology may participate in pathologic neovascular membrane formation in AMD.

Topics: Binding Sites; Cell Line; Cell Movement; Cell Proliferation; Choroid; Choroidal Neovascularization; Elastin; Endothelium, Vascular; Humans; Immunoenzyme Techniques; Macular Degeneration; Microscopy, Electron, Scanning; Peptide Fragments; Wound Healing

To study and reveal genetic variation in the elastin gene (ELN) that may be associated with neovascular age-related macular degeneration (AMD) and/or polypoidal choroidal vasculopathy (PCV). Eyes with neovascular AMD and PCV exhibit substantially different structural alterations of the elastic layer in the Bruch's membrane. The hypothesis for the present study was that ELN polymorphisms may play a role in the development of neovascular AMD and PCV and that genetic differences in ELN between these two phenotypes may be a reason for the histopathologic differences. To test these hypotheses, ELN was screened for genetic variation in a Japanese case-control dataset.. Two hundred eighty-five subjects were enrolled: 78 with neovascular AMD, 103 with PCV, and 104 control. We genotyped five tagged single nucleotide polymorphisms (SNPs) in ELN, and allele, genotype, and haplotype frequency distributions among neovascular AMD, PCV, and control subjects were compared by chi(2) tests.. A common ELN variant was significantly associated with susceptibility to PCV. The age- and sex-adjusted odds ratio was 7.56 for individuals homozygous for the risk allele compared with those carrying no more than one copy of the risk allele. Significantly different distributions were found in allele and haplotype frequencies between neovascular AMD and PCV in this region, but no particular ELN SNPs or haplotypes were significantly associated with neovascular AMD.. The findings implicate ELN as a susceptibility gene for PCV, and suggest that a different pathogenic process may be involved in the phenotypic expression of neovascular AMD and PCV.

Topics: Aged; Aged, 80 and over; Case-Control Studies; Choroid; Choroidal Neovascularization; Elastin; Female; Genetic Predisposition to Disease; Genetic Variation; Genotype; Humans; Macular Degeneration; Male; Middle Aged; Odds Ratio; Peripheral Vascular Diseases; Polymorphism, Single Nucleotide; Sequence Tagged Sites

Dysregulation of the extracellular matrix (ECM) plays an important role in the pathogenesis of age-related macular degeneration (AMD). Elastin is a fibrous protein constituent of the ECM, degradation of which may be detected by the presence of serum elastin-derived peptides (S-EDPs) in circulation. This study was undertaken to estimate levels of S-EDPs in patients with AMD compared with age-matched control subjects.. Fifty-six patients with AMD were classified into two groups: early age-related maculopathy (ARM) and neovascular AMD. The control group consisted of 15 age-matched subjects with no AMD. S-EDP levels in the serum of these subjects was estimated by competitive ELISA, using solubilized alpha-elastin from human aorta and polyclonal antibodies to this antigen.. S-EDPs were significantly higher in patients with AMD than in control subjects. In addition, subjects with neovascular AMD had higher levels of S-EDPs than did those with early disease.. The cause of this association between S-EDPs and AMD is unknown, but it suggests that systemic elastin degradation may increase the risk of conversion from early ARM to neovascular AMD. Further studies are needed to confirm whether the serum level of S-EDPs is a useful predictor of conversion from early ARM to neovascular AMD.

Topics: Aged; Aged, 80 and over; Aging; Antibody Specificity; Elastin; Enzyme-Linked Immunosorbent Assay; Female; Humans; Macular Degeneration; Male; Middle Aged; Peptides; Retinal Neovascularization

Topics: Elastin; Extracellular Matrix Proteins; Humans; Macular Degeneration; Mutation, Missense; Recombinant Proteins; Retinal Drusen

Mutations in the tissue inhibitor of metalloproteinases-3 (TIMP-3) gene have previously been identified in patients with Sorsby's fundus dystrophy (SFD). We evaluated the ocular distribution of TIMP-3 and other extracellular constituents in SFD.. The eyes of an SFD donor with a confirmed TIMP-3 mutation were examined using histologic techniques demonstrating connective tissue, calcium, and lipid. Immunohistochemical analyses were performed using antibodies against TIMP-3, collagen type IV, V, and VI, laminin, fibronectin, elastin, and fibrillin. Electron microscopy also was used.. A subretinal pigment epithelium (sub-RPE) deposit similar to that previously described was seen. A morphologically similar but different deposit was present internal to the nonpigmented ciliary epithelium (NPCE). Both deposits contained collagens, elastin, glycosaminoglycans, lipids, and calcium. Immunolabeling of TIMP-3 was found in the basement membrane of the NPCE, Bruch's membrane, and choroidal vessels in normal control subjects. In SFD, immunolabeling of TIMP-3 also was present in the sub-RPE deposit and in the inner portion of the ciliary body deposit. TIMP-3 immunoreactivity was more extensive in the SFD eye. The pattern of elastin immunoreactivity was remarkably similar to that of TIMP-3. Electron microscopy revealed a morphologically altered elastic layer of the Bruch's membrane.. Sub-RPE TIMP-3 immunoreactivity appears more extensive in SFD than in control subjects. There is also a correspondence between TIMP-3 and elastin immunoreactivies, which invites speculation as to a link between the SFD TIMP-3 mutation and altered elastin processing. The accumulation of abnormal material in SFD is more widespread than previously reported. In view of this, SFD might be better termed Sorsby's ocular epitheliopathy.

Topics: Aged; Basement Membrane; Ciliary Body; Collagen; Elastin; Female; Fundus Oculi; Humans; Immunoenzyme Techniques; Macular Degeneration; Mutation; Pigment Epithelium of Eye; Tissue Inhibitor of Metalloproteinase-3