Gene networks determine predisposition to AMD.

PURPOSE: AMD genetic studies have revealed various genetic loci as causal to AMD pathology. We have described the genetic complexity of Indian AMD by describing the interaction of genotypes and subsequent changes in protein expression under the influence of environmental factors. This can be utilized to enhance the diagnostic and therapeutic efficacy in AMD patients. DESIGN: Genotype association was studied in 464 participants (AMD =277 & controls = 187) for eight genetic variants and their corresponding protein expression METHODS: SNP analysis and protein expression analysis was carried out in AMD and controls in tandem with longitudinal assessment of protein levels during the course of AMD pathology. ANCOVA and contrast analysis were used to examine the genotypic interactions and corresponding alterations in protein levels. In order to identify the important genetic variants Logistic Regression (LR) modeling was carried out and to authenticate the model Area under the Receiver Operating Characteristic curve (AUROC) were also computed. RESULTS: We have found genetic variants of rs5749482 (TIMP-3), rs11200638 (HTRA1), rs769449 (APOE) and rs6795735 (ADAMTS9) to be associated with AMD, concomitant with significant alterations of studied proteins levels. Analysis also revealed that the genetic interaction between APOE-HTRA1 genotypes and changes in LIPC levels (>6 pg/ug) by one unit change in SNP, play a crucial role in AMD. LR model suggested that the seven factors (including both genetic and environmental) can be utilized to predict the AMD cases with 88% efficacy and 95.6% AUROC. CONCLUSION: Results suggest that diagnostic and therapeutic strategy for Indian AMD must include estimation of genetic interaction and concomitant changes in expression levels of proteins under influence of environmental factors.

Centrosomal protein CP110 controls maturation of the mother centriole during cilia biogenesis.

Defects in cilia centrosomal genes cause pleiotropic clinical phenotypes, collectively called ciliopathies. Cilia biogenesis is initiated by the interaction of positive and negative regulators. Centriolar coiled coil protein 110 (CP110) caps the distal end of the mother centriole and is known to act as a suppressor to control the timing of ciliogenesis. Here, we demonstrate that CP110 promotes cilia formation in vivo, in contrast to findings in cultured cells. Cp110(-/-) mice die shortly after birth owing to organogenesis defects as in ciliopathies. Shh signaling is impaired in null embryos and primary cilia are reduced in multiple tissues. We show that CP110 is required for anchoring of basal bodies to the membrane during cilia formation. CP110 loss resulted in an abnormal distribution of core components of subdistal appendages (SDAs) and of recycling endosomes, which may be associated with premature extension of axonemal microtubules. Our data implicate CP110 in SDA assembly and ciliary vesicle docking, two requisite early steps in cilia formation. We suggest that CP110 has unique context-dependent functions, acting as both a suppressor and a promoter of ciliogenesis.

Does toll-like receptor-3 (TLR-3) have any role in Indian AMD phenotype?

Age-related macular degeneration (AMD) is a devastating disease that results in irreversible central vision loss. TLRs signaling pathway has been found to play an important role in AMD pathogenesis as evidenced by several studies. The objective of the study was to determine the single nucleotide polymorphism (SNP) changes in TLR3 in North Indian AMD patients. We recruited 176 patients comprising 115 AMD patients and 61 controls. Real time PCR was used to evaluate the SNP changes at rs3775291 locus. Pearson's χ(2) test was used evaluate association between various groups. No significant association in genotype and allele frequency was found in AMD patients as compared to control. The results suggest that AMD pathology in North Indian AMD patients is not affected by TLR3 signaling but it could be influenced by other genetic or environmental factors unique to North India.

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.

Mitigation of total body irradiation-induced mortality and hematopoietic injury of mice by a thrombopoietin mimetic (JNJ-26366821).

The threat of a nuclear attack has increased in recent years highlighting the benefit of developing additional therapies for the treatment of victims suffering from Acute Radiation Syndrome (ARS). In this work, we evaluated the impact of a PEGylated thrombopoietin mimetic peptide, JNJ-26366821, on the mortality and hematopoietic effects associated with ARS in mice exposed to lethal doses of total body irradiation (TBI). JNJ-26366821 was efficacious as a mitigator of mortality and thrombocytopenia associated with ARS in both CD2F1 and C57BL/6 mice exposed to TBI from a cobalt-60 gamma-ray source. Single administration of doses ranging from 0.3 to 1 mg/kg, given 4, 8, 12 or 24 h post-TBI (LD70 dose) increased survival by 30-90% as compared to saline control treatment. At the conclusion of the 30-day study, significant increases in bone marrow colony forming units and megakaryocytes were observed in animals administered JNJ-26366821 compared to those administered saline. In addition, enhanced recovery of FLT3-L levels was observed in JNJ-26366821-treated animals. Probit analysis of survival in the JNJ-26366821- and saline-treated cohorts revealed a dose reduction factor of 1.113 and significant increases in survival for up to 6 months following irradiation. These results support the potential use of JNJ-26366821 as a medical countermeasure for treatment of acute TBI exposure in case of a radiological/nuclear event when administered from 4 to 24 h post-TBI.

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.

Proteomic Changes in Mouse Spleen after Radiation-Induced Injury and its Modulation by Gamma-Tocotrienol.

Gamma-tocotrienol (GT3), a naturally occurring vitamin E isomer, a promising radioprotector, has been shown to protect mice against radiation-induced hematopoietic and gastrointestinal injuries. We analyzed changes in protein expression profiles of spleen tissue after GT3 treatment in mice exposed to gamma radiation to gain insights into the molecular mechanism of radioprotective efficacy. Male CD2F1 mice, 12-to-14 weeks old, were treated with either vehicle or GT3 at 24 h prior to 7 Gy total-body irradiation. Nonirradiated vehicle, nonirradiated GT3 and age-matched naïve animals were used as controls. Blood and tissues were harvested on days 0, 1, 2, 4, 7, 10 and 14 postirradiation. High-resolution mass-spectrometry-based radioproteomics was used to identify differentially expressed proteins in spleen tissue with or without drug treatment. Subsequent bioinformatic analyses helped delineate molecular markers of biological pathways and networks regulating the cellular radiation responses in spleen. Our results show a robust alteration in spleen proteomic profiles including upregulation of the Wnt signaling pathway and actin-cytoskeleton linked proteins in mediating the radiation injury response in spleen. Furthermore, we show that 24 h pretreatment with GT3 attenuates radiation-induced hematopoietic injury in the spleen by modulating various cell signaling proteins. Taken together, our results show that the radioprotective effects of GT3 are mediated, via alleviation of radiation-induced alterations in biochemical pathways, with wide implications on overall hematopoietic injury.

Resveratrol regulates body weight in healthy and ovariectomized rats.

OBJECTIVE: The elevated body weight in post-menopausal state attributes to the reduced estrogen levels which is alleviated by resveratrol (RES) but its role in control rats is not well understood. The main objective of the study was to explore the effects of RES on the body weight of ovariectomized (OVX) female rats with controls and to relate their biochemical parameters. METHODS: Female Wistar rats weighing 200-300 g underwent bilateral ovariectomy (OVX) and were fed soya free diet (n = 8 rats per group). In all groups: (Control, Control + Resveratrol, OVX and OVX + Resveratrol) resveratrol was administered orally at a dose of 5 mg/kg/day for 1 month. Glucose and other biochemical parameters were examined. RESULTS: Significant reduction in the gain of body weight was observed in the control rats treated with resveratrol. Ovariectomy caused an escalation in gain of body weight due to loss of estrogen which was brought down with resveratrol. There was a slight dip in the blood glucose levels after resveratrol treatment. CONCLUSION: Resveratrol significantly reduced the gain of body weight in the control rats and in OVX rats showing its antiobesogenic effects.

Why AMD is a disease of ageing and not of development: mechanisms and insights.

Ageing disorders can be defined as the progressive and cumulative outcome of several defective cellular mechanisms as well as metabolic pathways, consequently resulting in degeneration. Environment plays an important role in its pathogenesis. In contrast, developmental disorders arise from inherited mutations and usually the role of environmental factors in development of disease is minimal. Age related macular degeneration (AMD) is one such retinal degenerative disorder which starts with the progression of age. Metabolism plays an important role in initiation of such diseases of ageing. Cholesterol metabolism and their oxidized products like 7-ketocholesterol have been shown to adversely impact retinal pigment epithelium (RPE) cells. These molecules can initiate mitochondrial apoptotic processes and also influence the complements factors and expression of angiogenic proteins like VEGF etc. In this review we highlight why and how AMD is an ageing disorder and not a developmental disease substantiated by disrupted cholesterol metabolism common to several age related diseases.

CC chemokine receptor-3 as new target for age-related macular degeneration.

CC chemokine receptor-3 (CCR3) is involved in angiogenic processes. Recently, CCR3 was accounted to participate in choroidal neovascularization (CNV) and CCR3 targeting was reported to be superior to standard antivascular endothelial growth factor-A (VEGF-A) administration when tested in an artificially induced CNV in animals. As human CCR3 studies are lacking in age-related macular degeneration (AMD) patients we sought to determine if CCR3 has any association with inflammatory processes that occur in CNV. A total of 176 subjects were included on the basis of inclusion criteria. Real time PCR was used to analyze the single nucleotide polymorphism in CCR3 of AMD (115) and normal controls (n=61). Genotype frequency was adjusted for possible confounders like cigarette smoking, alcohol, meat consumption and other risk factors. Chi-square test was used for analysis of polymorphism. The genotype distribution of CCR3 (rs3091250) polymorphism was significantly different in AMD patients in the Indian population. GT (heterozygous) and TT (homozygous) at the rs3091250 SNP increased risk of AMD as compared to the GG genotypes (OR=4.8, CI 95%=2.2-10.8 and OR=4.1, CI 95%=1.6-10.1 respectively). Subgroup analysis of AMD patients in wet and dry revealed no significant differences. There was no significant difference for rs3091312 in AMD and control group. A significant association between AMD and CCR3 (rs3091250) polymorphism localized on chromosome 3p21.3 was detected. The results suggest the possible contribution of rs3091250, a new predisposing allele in 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 individual's 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.

Association between CFH Y402H polymorphism and age related macular degeneration in North Indian cohort.

The purpose of the study was to determine serum complement factor H (CFH) levels in patients of age related macular degeneration (AMD) and examine its association with CFH Y402H polymorphism. 115 AMD patients and 61 normal controls were recruited in this study. The single nucleotide polymorphism was assayed by real time PCR and serum CFH levels were measured by ELISA and standardized to total serum protein. Chi-square test was applied to polymorphism analysis while Mann Whitney U-statistic for CFH-levels. Mendelian randomization approach was used for determining causal relationship. The genotype frequency differed between the AMD patients (TT- 18.3%, TC-41.3% and CC-40.4%) and controls (TT-76.3%, TC-13.6%, and CC-10.1%) (p = 0001). The frequency of alleles was also significantly different when AMD (T-39% and C-61%) was compared to controls (T-83% and C-17%) (p = 0.0001). Level of serum CFH was significantly lower in AMD patients as compared to normal controls (p = 0.001). Our data showed that the CFH Y402H polymorphism is a risk factor for AMD in the North Indian population. Mendelian randomization approach revealed that CFH Y402H polymorphism affects AMD risk through the modification of CFH serum levels.

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 individual's 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 pearson's 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.

Single nucleotide polymorphisms in MCP-1 and its receptor are associated with the risk of age related macular degeneration.

BACKGROUND: Age-related macular degeneration (AMD) is the leading cause of blindness in the elderly population. We have shown previously that mice deficient in monocyte chemoattractant protein-1 (MCP1/CCL2) or its receptor (CCR2) develop the features of AMD in senescent mice, however, the human genetic evidence so far is contradictory. We hypothesized that any dysfunction in the CCL2 and its receptor result could be the contributing factor in pathogenesis of AMD. METHODS AND FINDINGS: 133 AMD patients and 80 healthy controls were enrolled for this study. Single neucleotid Polymorphism for CCL2 and CCR2 was analyzed by real time PCR. CCL2 levels were determined by enzyme-linked immunosorbent assay (ELISA) after normalization to total serum protein and percentage (%) of CCR2 expressing peripheral blood mononuclear cells (PBMCs) was evaluated using Flow Cytometry. The genotype and allele frequency for both CCL2 and CCR2 was found to be significantly different between AMD and normal controls. The CCL2 ELISA levels were significantly higher in AMD patients and flow Cytometry analysis revealed significantly reduced CCR2 expressing PBMCs in AMD patients as compared to normal controls. CONCLUSIONS: We analyzed the association between single neucleotide polymorphisms (SNPs) of CCL2 (rs4586) and CCR2 (rs1799865) with their respective protein levels. Our results revealed that individuals possessing both SNPs are at a higher risk of development of AMD.

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.