Neel Kamal Sharma

New biomarker for neovascular age-related macular degeneration: eotaxin-2.

Recently, eotaxin-CCR3 was reported to play an important role in choroidal neovascularization (CNV) development and was documented to be superior than vascular endothelial growth factor-A treatment when tested in CNV animals. As eotaxin studies are lacking in the human age-related macular degeneration (AMD) patients, we sought to determine whether eotaxin-2 (CCL24) has any association with inflammatory processes that occur in CNV. CCL24 levels were determined by enzyme linked immunosorbant assay (ELISA) after normalization to total serum protein and levels of ELISA were correlated to various risk factors in about 133 AMD patients and 80 healthy controls. The CCL24 levels were significantly higher in wet AMD patients as compared with dry AMD and normal controls. There was a significant difference when compared among wet AMD patients (i.e., minimally classic, predominantly classic, and occult). We also report significant difference in the CCL24 levels of Avastin-treated and untreated AMD patients. This study shows that CCL24 levels were found to be significantly increased in AMD patients despite Avastin treatment as compared with normal controls and those without Avastin, indicating that CCL24 may have an association with CNV and may be an important target to validate future therapeutic approaches in AMD in tandem with Avastin treatment.

Single nucleotide polymorphism and serum levels of VEGFR2 are associated with age related macular degeneration.

Age-related macular degeneration (AMD) is a leading cause of blindness and is the third leading cause of blindness. Genetic factors are known to influence an individuals risk for developing AMD. Linkage has earlier been shown to the vascular endothelial growth factor 2 (VEGF2) gene and AMD. To examine the role of VEGFR2 in north Indian population, we conducted a case control study. Total 176 subjects were enrolled in a case-control genetic study. Real-Time PCR was used to analyze the SNPs (rs1531289 and rs2305948) of VEGFR-2 gene. ELISA was conducted to determine the levels of VEGFR2. A non-parametric Mann-Whitney-U test was applied for comparison of the ELISA levels and pearsons Chi-square test was applied to study the association of polymorphism between various groups. The single SNP (rs1531289) AG genotype was significantly associated with AMD (OR= 2.13, 95%CI= 1.011-4.489, P=0.047). VEGFR2 levels were found to be increased significantly in AMD patients as compared to normal controls. We also found significant increase in the levels of wet AMD as compared to dry AMD. This study demonstrates higher levels of VEGFR2 and frequency of AG (rs1531289) genotype in AMD patient population, suggesting the role of VEGFR-2 in pathogenesis of AMD.

Predictive Model for Earlier Diagnosis of Suspected Age-Related Macular Degeneration Patients

The primary goal of tailored medicine is to presymptomatically identify individuals at high risk for disease using information of each individuals genetic profile and collection of environmental risk factors. Recently, algorithms were given the strong recognition of several replicated risk factors for age-related macular degeneration (AMD), this distant goal is beginning to seem less mysterious. The purpose of the study was to develop a statistical model for AMD. This study includes total 106 subjects. To identify the risk of earlier diagnosis of suspected AMD patients, 22 independent variables were included in the study. Forward stepwise (likelihood ratio) binary logistic regression has been used to find significant variables associated with the risk of AMD. Prediction equation, based on significant risk factors, and model authenticity have been developed. Hosmer-Lemeshow goodness of fit statistic (χ(2)=0.143, df=8, p=1.0), which is nonsignificant, indicates the appropriateness of the logistic regression model to predict AMD. After going through stepwise logistic regression, only 6 variables out of the 22 independent variables, namely, serum complement factor H (CFH), serum chemokine (C-C motif) ligand 2 (CCL2), serum superoxide dismutase 1 (SOD1), polymorphism in CCL2 (rs4586), stress, and comorbidity were found to be significant (p<0.05). The binary logistic regression model is an appropriate tool to predict AMD in the presence of serum CFH, serum CCL2, serum SOD1, polymorphism in CCL2 (rs4586), stress, and comorbidity with high specificity and sensitivity. The area under the receiver operating characteristic curve (0.909, p=0.001) with less standard error of 0.034 and close 95% confidence intervals (0.842-0.976) further validates the model.

Does DcR1 (TNF-related apoptosis-inducing-ligand Receptor 3) have any role in human AMD pathogenesis?

It has been postulated that there is a link between age related degenerative diseases and cancer. The TNF-related apoptosis-inducing ligand (TRAIL) has been shown to selectively kill tumor cells by binding to pro-apoptotic and anti-apoptotic receptors. Our aim was to study the levels of anti-apoptotic receptor (DcR1) in age related macular degeneration (AMD) and controls. AMD patients (115) were classified into two groups: Dry and Wet AMD. Wet AMDs were further classified into occult, predominant classic and minimal classic. 61 healthy individuals were recruited as normal controls. After normalization with total protein, DcR1 levels were analyzed by ELISA. Mann Whitney U-statistic was used for analysis of DcR1 ELISA results. We have observed DcR1 levels in serum sample which were significantly lower in AMD patients as compared to controls (p = 0.001). On the other hand, we did not find difference in DcR1 levels between wet and dry AMD. The present study defines the plausible role of DcR1 in AMD pathology signifying a new therapeutic target for AMD.

Age related macular degeneration – advances and trends

Age related macular degeneration (AMD) is the most common cause of visual impairment and is characterized by drusen formation, geographic atrophy and gradual loss of vision. It is a frightening disease that destroys the macula, the central part of retina, severely regimenting a persons normal sight. The utility of mouse models with features of AMD along with its recently reported association with complement factor H-gene, and TLR 4 genes strongly suggest the importance of inflammatory mediators and complement in the pathogenesis of this disease. Current treatment modalities include photodynamic therapy and photocoagulation, however, their efficacy is limited. The animal models that faithfully replicate the features of human AMD are useful platforms in validating new therapies. This not only provides new insights for preventative and restorative approaches in AMD in future but also advances our understanding of cardiovascular and neurodegenerative disorders. doi : 10.5214/ans.0972.7531.2009.160208 Competing interests: None. Source of Funding: None Received Date: 01 April 2009 Revised Date: 25 April 2009 Accepted Date: 02 May 2009

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.

Exploring the role of VEGF in Indian Age related macular degeneration.

Background Age related macular degeneration (AMD) is major devastating neurodegenerative disorder characterized by progressive irreversible vision loss in the elderly persons. In spite of several genetic and environmental factors, the role of VEGF and CFH predispose the pathological phenomenon in the AMD patients. Purpose The aim of the study was to estimate the VEGF levels in the serum of AMD patients and its correlation with co-morbidity of the participants. Methods The study recruited the 98 AMD patients and 59 controls with proper consent of the participants as per the exclusion-inclusion criteria. The co-morbidity and socio-economic details were obtained by introducing the standard questionnaire amongst the participants. Serum levels of vascular endothelial growth factor (VEGF) was estimated by ELISA and compared with the control population of the study. The levels of VEGF in the serum of AMD patients and controls were compared with Mann-Whitney U-test. Kruskal Wallis one-way analysis of variance (ANOVA) was employed to analyze more than two variables in the study. Results Elevated level of VEGF was found in AMD patients as compared to controls. Surprisingly, we did not find significant changes among wet AMD subtypes i.e. minimal, predominant and classic wet AMD. However, we have demonstrated the intravitreal anti-VEGF treatment (avastin) in AMD patients could reduce the systemic VEGF levels although it was not significant. Moreover, the heart ailment in the AMD patients could also influence the VEGF levels. Conclusion Our study is consistent with previous studies describing the imperative significance of VEGF in AMD pathology. However, our study did not reveal the role of VEGF in wet AMD progression but it is well established causative agent for the same. The increased levels of VEGF in heart ailment among AMD patients are significant.

Using current data to define new approach in age related macular degeneration: need to accelerate translational research.

Age related macular degeneration (AMD) is one of the major retinal degenerative disease of ageing whose complex genetic basis remains undeciphered. The involvement of various other factors like mitochondrial genes, cytoskeletal proteins and the role of epigenetics has been described in this review. Several population based AMD genetic studies have been carried out worldwide. Despite the increased publication of reports, clinical translation still eludes this davastating disease. We suggest models to address roadblocks in clinical translation hoping that these would be beneficial to drive AMD research towards innovative biomarkers and therapeutics Therefore, addressing the need large autopsy studies and combining it with efficient use of bioinformatic tools, statistical modeling and probing SNP-biomarker association are key to time bound resolution of this disease.

CCL2 single nucleotide polymorphism of rs1024611 implicates prominence of inflammatory cascade by univariate modeling in Indian AMD

Background The role of chemotactic protein CCL2/MCP-1 has been widely explored in age related macular degeneration (AMD) patients as well as animal models through our previous studies. Aim Aim of the study was to examine the association of another variance of CCL2, rs1024611 in pathophysiology of AMD. Methods This particular SNP has been found to be involved in inflammatory processes in various diseases. Total 171 subjects were recruited in the study with all demographic details by administering a standard questionnaire. SNP analysis was performed with TaqMan assay. Linear univariate and ANCOVA modeling was performed to show the interaction of rs1024611 with another SNP variant of CCL-2/CCR-2 (rs4586 and rs1799865) and impact of individual genotypes on CCL-2 expression in the context of AMD pathology. Results Results showed that both heterozygous (AG, p = 0.01) and homozygous (GG, p = 0.0001) genotypes are associated with AMD pathology. Allele frequency analysis showed that ‘G’ allele is frequent in AMD patients as compared to controls (p = 0.0001). Moreover, AMD patients who smoke were found to be associated with ‘AG’ genotype (p = 0.0145). Although, we did not find any significant interaction between the SNP variants by linear univariate analysis but results show the effect of ‘CT’ genotype on ‘TT’ genotype in rs4586 by considering rs1024611 as covariate. Conclusion Based on these results it is imperative that CCL2 mediated pathology may be associated with AMD.

Role of Ionizing Radiation in Neurodegenerative Diseases

Ionizing radiation (IR) from terrestrial sources is continually an unprotected peril to human beings. However, the medical radiation and global radiation background are main contributors to human exposure and causes of radiation sickness. At high-dose exposures acute radiation sickness occurs, whereas chronic effects may persist for a number of years. Radiation can increase many circulatory, age related and neurodegenerative diseases. Neurodegenerative diseases occur a long time after exposure to radiation, as demonstrated in atomic bomb survivors, and are still controversial. This review discuss the role of IR in neurodegenerative diseases and proposes an association between neurodegenerative diseases and exposure to IR.