Evaluation of cardiovascular biomarkers in patients with age-related wet macular degeneration

Efficacy of Anti-Vascular Endothelial Growth Factor Treatment in Neovascular Age-Related Macular Degeneration and Systemic Cardiovascular Risk Factors

This study evaluates whether the presence of cardiovascular risk factors (CRFs) affects functional and morphological responses to anti–vascular endothelial growth factor (VEGF) therapy in patients with neovascular age-related macular degeneration (nAMD). Retrospective analysis included 98 treatment-naïve eyes followed for at least 12 months. Patients received intravitreal injections of ranibizumab or aflibercept with the dosage and regimen set according to each manufacturer’s recommendations for their product. Parameters evaluated at each follow-up visit included best-corrected visual acuity and central retinal thickness. Additionally, the presence of the following CRFs was evaluated: male sex, age of older than 70 years, history of current or past smoking, systemic arterial hypertension, diabetes mellitus, total hypercholesterolemia, low-density lipoprotein hypercholesterolemia, high-density lipoprotein concentration of 45 mg/dL or less, atherogenic dyslipidemia, family history of cardiovascular disease, and chronic kidney disease. A statistically significant better letter gain in visual acuity (p = 0.012) and greater percentage of responders (p = 0.035)—that is patients in whom best corrected visual acuity was stabilized or improved at 12 months—were noted among patients without a diagnosis of arterial hypertension. A statistically significant better mean visual improvement was also achieved in patients with higher total cholesterol plasma levels (p = 0.004), but this finding was not reflected in the significantly higher percentage of responders. The presence of remaining analyzed risk factors did not substantially affect the results of treatment. Systemic arterial hypertension is an independent factor leading to a poor functional outcome following anti-VEGF therapy in patients with nAMD. Effects of anti-VEGF treatment in patients with high total cholesterol levels should be analyzed in further research.

Evaluation of Blood Coagulation Parameters and ADMA, NO, IL-6, and IL-18 Serum Levels in Patients with Neovascular AMD before, during, and after the Initial Loading Phase of Intravitreal Aflibercept

We evaluated the effect of intravitreal injections of aflibercept (IVA) on blood coagulation parameters including prothrombin time (PT), activated partial thromboplastin time (APTT), and thrombin time (TT), as well as asymmetric dimethylarginine (ADMA), nitric oxide (NO), interleukin 6 (IL-6), and interleukin 18 (IL-18) serum levels in patients with neovascular AMD (nAMD). Twenty-two eyes of 22 patients with nAMD were included. Parameters were evaluated before and 2–3 days after the first IVA injection, and then immediately before and 2–3 days after the third IVA injection. We revealed prolongation of the TT after the initial loading phase of IVA (p = 0.041) and a significant increase in IL-18 serum concentration immediately before the third IVA administration compared to baseline (p = 0.037). There were no statistically significant differences of other parameters and PT, APTT, ADMA, NO, and IL-6 values remained within the normal range at each of the time points of the study. Our results suggest that repeated IVA administration may affect the common blood coagulation pathway, which manifests as a prolongation of the TT value. Furthermore, we showed a significant increase in serum concentration of the pro-inflammatory cytokineIL-18during the initial loading phase of IVA.

Protecting the aging eye with hydrogen sulfide

Research demonstrates that senescence is associated with tissue and organ dysfunction, and the eye is no exception. Sequelae arising from aging have been well defined as distinct clinical entities and vision impairment has significant psychosocial consequences. Retina and adjacent tissues like retinal pigmented epithelium and choroid are the key structures that are required for visual perception. Any structural and functional changes in retinal layers and blood retinal barrier could lead to age-related macular degeneration, diabetic retinopathy, and glaucoma. Further, there are significant oxygen gradients in the eye that can lead to excessive reactive oxygen species, resulting in endoplasmic reticulum and mitochondrial stress response. These radicals are source of functional and morphological impairment in retinal pigmented epithelium and retinal ganglion cells. Therefore, ocular diseases could be summarized as disturbance in the redox homeostasis. Hyperhomocysteinemia is a risk factor and causes vascular occlusive disease of the retina. Interestingly, hydrogen sulfide (H₂S) has been proven to be an effective antioxidant agent, and it can help treat diseases by alleviating stress and inflammation. Concurrent glutamate excitotoxicity, endoplasmic reticulum stress, and microglia activation are also linked to stress; thus, H₂S may offer additional interventional strategy. A refined understanding of the aging eye along with H₂S biology and pharmacology may help guide newer therapies for the eye.

Blood platelet and serum bilirubin in the diagnosis of central serous chorioretinopathy

Diagnostic value of blood platelet (PLT) and serum total bilirubin (TBIL) for central serous chorioretinopathy (CSC) was investigated. A total of 537 patients with CSC and 182 people with normal physical conditions were selected from June 2012 to August 2016. The 537 patients included 294 males and 243 females with an average age of 45.5±17.8 years, and all patients were treated in the Department of Ophthalmology of Yantai Hospital of Traditional Chinese Medicine and the Department of Ophthalmology of Yantai Liuhuangding Hospital. Clinical data of the patients were retrospectively analyzed. The 182 people with normal physical conditions included 103 males and 79 females with an average age of 43.6±15.2 years, and they were set as the control group. PLT and TBIL tests at admission and after treatment were collected and compared between CSC and the control group to analyze the diagnostic values of PLT and TBIL for CSC. PLT level in the CSC group was significantly higher than that in the control group, but TBIL level in the CSC group was significantly lower than that in the control group (p<0.05). Linear correlation analysis showed that PLT was a risk factor for CSC, and TBIL was a protective factor for CSC. The sensitivity of PLT and TBIL in diagnosis of CSC was 75.2 and 72.7%, respectively, and the specificity of PLT and TBIL in diagnosis of CSC was 65.8 and 63.3%, respectively. PLT of CSC patients was significantly higher than that of the control group, and TBIL of CSC patients was significantly lower than that of the control group, but they both gradually reduced to normal levels after treatment, which can be regarded as the index for the clinical diagnosis of CSC in the future.

Homocysteine and risk of age-related macular degeneration: a systematic review and meta-analysis

There is still no agreement on total plasma homocysteine (tHcy) role in age-related macular degeneration (AMD), the leading cause of new blindness in industrialized countries. We performed a systematic review and meta-analysis of the published data on the correlation between tHcy and AMD. MEDLINE/PubMed and ISI Web of Sciences searches were performed according to MOOSE guidelines. Case-control studies were eligible for inclusion. Participants and controls were AMD patients and subjects without AMD. The main outcome measure was wet AMD. Homocysteine level was the main exposure variable. Data were pooled using a random-effects model. Twelve case-control studies were identified: 10 assessed wet AMD, four dry AMD, one early AMD, one late AMD, and one any AMD. As for wet AMD, there was a total of 453 cases and 514 controls. Mean tHcy was on average 1.1 μmol/l (95% confidence interval [CI] = 0.96-1.25) greater in wet AMD cases, but there was evidence of extreme between-study heterogeneity (p < 0.001, I²  = 91.8%). In a model homogenous for age, including six wet AMD studies (214 cases, 274 controls), mean tHcy was on average 0.58 μmol/l (95% CI = 0.35-0.73) greater in the case group, a not statistically significant result (p = 0.144) associated with moderate heterogeneity (I²  = 39.2%). Our meta-analysis indicates that there is some weak evidence that increased tHcy might be associated with wet AMD; however, this result should be interpreted cautiously, because of a marked between-study heterogeneity and the possible effect of publication bias. Future studies, preferably of cohort design, are necessary before any firm conclusions on the putative role of increased tHcy on AMD can be drawn.

Color Doppler imaging of the retrobulbar circulation and plasmatic biomarkers of vascular risk in age-related macular degeneration: A pilot study

PURPOSE

To evaluate preliminarily and compare the level of plasmatic biomarkers of vascular risk in patients with and without exudative age-related macular degeneration (ARMD) and to relate it to vascular resistance alterations in the ophthalmic artery (OA), central retinal artery (CRA), posterior temporal ciliary artery (PTCA), and posterior nasal ciliary artery (PNCA).

METHODS

Color Doppler imaging of the OA, CRA, PTCA, and PNCA was performed in 30 eyes of 30 cataract patients (control group) as well as in 30 eyes of 30 patients with naive exudative ARMD (study group), measuring the peak systolic velocity, end-diastolic velocity (EDV), and Pourcelot resistive index (RI). Likewise, in both groups, a blood test was performed to determine the plasmatic levels of homocysteine, C-reactive protein (CRP), B12 vitamin, and folic acid.

RESULTS

A positive and significant correlation was found between the level of CRP and RI of the OA in the ARMD group (r = 0.498, P = 0.005), with an increased RI in all arteries compared to controls, although differences only reached statistical significance for the PTCA (P = 0.035). Likewise, a significantly lower EDV for the CRA was found in ARMD eyes compared to controls (P = 0.041). In the study group, significantly higher plasmatic levels of homocysteine (P = 0.042) and CRP (P = 0.046) were found. In contrast, no significant differences were found between groups in the levels of folic acid (P = 0.265) and B12 vitamin (P = 0.520).

CONCLUSION

The decrease of the choroidal perfusion related to hyperhomocysteinemia, and increase in the CRP plasmatic levels may play an etiological role on the exudative ARMD. This should be investigated in future studies with larger samples of patients.

The Relationship Between Nonsteroidal Anti-inflammatory Drug Use and Age-related Macular Degeneration

PURPOSE

To describe the relationship between the incidence of age-related macular degeneration (AMD) and nonsteroidal anti-inflammatory drug (NSAIDs) use.

DESIGN

Prospective cohort study.

METHODS

This study consisted of participants in the California Men's Health Study. Those who completed surveys in 2002-2003 and 2006 were included. Men who self-reported use of aspirin, ibuprofen, naproxen, valdecoxib, celecoxib, and/or rofecoxib at least 3 days per week were considered NSAID users. Patients were categorized as non-users, former users, new users, or longer-term users based on survey responses. NSAID use was also categorized by type: any NSAIDs, aspirin, and/or non-aspirin NSAIDs. Age, race/ethnicity, smoking status, education, income, alcohol use, and Charlson comorbidity index score were included in the multivariate analysis as risk factors for AMD.

RESULTS

A total of 51 371 men were included. Average follow-up time was 7.4 years. There were 292 (0.6%) and 1536 (3%) cases of exudative and nonexudative AMD, respectively. Longer-term use of any NSAID was associated with lower risk of exudative AMD (hazard ratio [HR] 0.69, 95% confidence interval [CI] 0.50-0.96, P = .029). New users of any NSAIDs (HR = 0.79, 95% CI 0.68-0.93, P = .0039) and aspirin (HR = 0.82, 95% CI 0.70-0.97, P = .018) had a lower risk of nonexudative AMD, although this trend did not persist in longer-term users. The relationship between exudative or nonexudative AMD and the remaining categories of NSAID use were not significant.

CONCLUSION

The overall impact of NSAIDs on AMD incidence is small; however, the lower risk of exudative AMD in longer-term NSAID users may point to a protective effect and deserves further study as a possible mechanism to modulate disease risk.

Epigenetic modifications in hyperhomocysteinemia: potential role in diabetic retinopathy and age-related macular degeneration

To study Hyperhomocysteinemia (HHcy)-induced epigenetic modifications as potential mechanisms of blood retinal barrier (BRB) dysfunction, retinas isolated from three- week-old mice with elevated level of Homocysteine (Hcy) due to lack of the enzyme cystathionine β-synthase (cbs^-/- , cbs^+/- and cbs^+/+ ), human retinal endothelial cells (HRECs), and human retinal pigmented epithelial cells (ARPE-19) treated with or without Hcy were evaluated for (1) histone deacetylases (HDAC), (2) DNA methylation (DNMT), and (3) miRNA analysis. Differentially expressed miRNAs in mice with HHcy were further compared with miRNA analysis of diabetic mice retinas (STZ) and miRNAs within the exosomes released from Hcy-treated RPEs. Differentially expressed miRNAs were further evaluated for predicted target genes and associated pathways using Ingenuity Pathway Analysis. HHcy significantly increased HDAC and DNMT activity in HRECs, ARPE-19, and cbs mice retinas, whereas inhibition of HDAC and DNMT decreased Hcy-induced BRB dysfunction. MiRNA profiling detected 127 miRNAs in cbs^+/- and 39 miRNAs in cbs^-/- mice retinas, which were significantly differentially expressed compared to cbs^+/+ . MiRNA pathway analysis showed their involvement in HDAC and DNMT activation, endoplasmic reticulum (ER), and oxidative stresses, inflammation, hypoxia, and angiogenesis pathways. Hcy-induced epigenetic modifications may be involved in retinopathies associated with HHcy, such as age-related macular degeneration and diabetic retinopathy.

Risk factors and biomarkers of age-related macular degeneration

A biomarker can be a substance or structure measured in body parts, fluids or products that can affect or predict disease incidence. As age-related macular degeneration (AMD) is the leading cause of blindness in the developed world, much research and effort has been invested in the identification of different biomarkers to predict disease incidence, identify at risk individuals, elucidate causative pathophysiological etiologies, guide screening, monitoring and treatment parameters, and predict disease outcomes. To date, a host of genetic, environmental, proteomic, and cellular targets have been identified as both risk factors and potential biomarkers for AMD. Despite this, their use has been confined to research settings and has not yet crossed into the clinical arena. A greater understanding of these factors and their use as potential biomarkers for AMD can guide future research and clinical practice. This article will discuss known risk factors and novel, potential biomarkers of AMD in addition to their application in both academic and clinical settings.

Serum levels of lipid metabolites in age-related macular degeneration

Age-related macular degeneration (AMD) is a neurodegenerative disease that causes adult-onset blindness. There are 2 forms of this progressive disease: wet and dry. Currently there is no cure for AMD, but several treatment options have started to emerge making early detection critical for therapeutic success. Analysis of the eyes of Abca4(-/-)Rdh8(-/-) mice that display light-induced retinal degeneration indicates that 11-cis-retinal and docosahexaenoic acid (DHA) levels were significantly decreased as compared with the eyes of control dark-adapted C57BL/6J mice. In addition, exposure to intense light correlated with higher levels of prostaglandin G2 in the eyes of Abca4(-/-)Rdh8(-/-) mice. Intense light exposure also lowered DHA levels in the eyes of wild-type C57BL/6J mice without discernible retinal degeneration. Analysis of human serum from patients with AMD recapitulated these dysregulated DHA levels and revealed dysregulation of arachidonic acid (AA) levels as well (∼32% increase in patients with AMD compared with average levels in healthy individuals). From these observations, we then built a statistical model that included levels of DHA and AA from human serum. This model had a 74% probability of correctly identifying patients with AMD from controls. Addition of a genetic analysis for one of the most prevalent amino acid substitutions in the age-related maculopathy susceptibility 2 gene linked to AMD, Ala(69)→Ser, did not improve the statistical model. Thus, we have characterized a reliable method with the potential to detect AMD without a genetic component, paving the way for a larger-scale clinical evaluation. Our studies on mouse models along with the analysis of human serum suggest that our small molecule-based model may serve as an effective tool to estimate the risk of developing AMD.