Association of monocyte chemoattractant protein-1 (MCP-1) 2518A/G polymorphism with proliferative diabetic retinopathy in Korean type 2 diabetes

Association between the MCP-1 -2518 A > G (rs1024611) polymorphism and susceptibility to type 2 diabetes mellitus and diabetic nephropathy: a meta-analysis

BACKGROUND

Studies evaluating the association between monocyte chemoattractant protein-1 (MCP-1) -2518 A > G (rs1024611) polymorphism and type 2 diabetes mellitus (T2DM) and diabetic nephropathy (DN) are contradictory. The present study aims to provide a comprehensive assessment and more reliable estimation of the relationship between the MCP-1 rs1024611 polymorphism and T2DM and DN risk.

METHODS

Eligible articles were retrieved from the PubMed, Web of Science, EMBASE, Cochrane, and China National Knowledge Infrastructure databases. The effect summary odds ratios (ORs) and 95% confidence intervals (CIs) were obtained to calculate the summary effect size. Heterogeneity was analyzed by subgroup analysis and meta-regression. Publication bias was tested using funnel plots and Egger's test.

RESULTS

In total, sixteen studies were included. Thirteen studies involving 2,363 patients with T2DM and 4,650 healthy controls found no significant association between the MCP-1 rs1024611 polymorphism and T2DM in the overall population. Ethnicity stratification found an association between the GG + GA genotype and decreased T2DM risk in Caucasians (OR = 0.79, 95% CI: 0.66-0.93, P = 0.006; PQ = 0.372). No significant risks were found in the Asian population for any genetic models. Seven studies found an association between the GG + GA genotype and DN risk in the Asian population (OR = 1.37, 95% CI: 1.11-1.71, P = 0.004, PQ = 0.222). No significant risks were found in the Caucasian population with any genetic models. There were no statistically significant differences in genotype distribution between patients with T2DM and DN in Asians or Caucasians. Meta-regression revealed that genotyping method was a major driver of heterogeneity in five genetic models (GG + GA vs. AA: P = 0.032; GG vs. GA + AA: P = 0.028; GG vs. AA: P = 0.035; GG vs. GA: P = 0.041; G vs. A: P = 0.041).

CONCLUSION

The MCP-1 rs1024611 polymorphism is associated with susceptibility to T2DM in Caucasians and DN in Asians. Larger, well-designed cohort studies are needed in the future to verify this association.

Integrating Common Risk Factors with Polygenic Scores Improves the Prediction of Type 2 Diabetes

We tested associations between 13 established genetic variants and type 2 diabetes (T2D) in 1371 study participants from the Volga-Ural region of the Eurasian continent, and evaluated the predictive ability of the model containing polygenic scores for the variants associated with T2D in our dataset, alone and in combination with other risk factors such as age and sex. Using logistic regression analysis, we found associations with T2D for the CCL20 rs6749704 (OR = 1.68, P_FDR = 3.40 × 10^-5), CCR5 rs333 (OR = 1.99, P_FDR = 0.033), ADIPOQ rs17366743 (OR = 3.17, P_FDR = 2.64 × 10^-4), TCF7L2 rs114758349 (OR = 1.77, P_FDR = 9.37 × 10^-5), and CCL2 rs1024611 (OR = 1.38, P_FDR = 0.033) polymorphisms. We showed that the most informative prognostic model included weighted polygenic scores for these five loci, and non-genetic factors such as age and sex (AUC 85.8%, 95%CI 83.7-87.8%). Compared to the model containing only non-genetic parameters, adding the polygenic score for the five T2D-associated loci showed improved net reclassification (NRI = 37.62%, 1.39 × 10^-6). Inclusion of all 13 tested SNPs to the model with age and sex did not improve the predictive ability compared to the model containing five T2D-associated variants (NRI = -17.86, p = 0.093). The five variants associated with T2D in people from the Volga-Ural region are linked to inflammation (CCR5, CCL2, CCL20) and glucose metabolism regulation (TCF7L, ADIPOQ2). Further studies in independent groups of T2D patients should validate the prognostic value of the model and elucidate the molecular mechanisms of the disease development.

The association of AGER and ALDH2 gene polymorphisms with diabetic retinopathy

PURPOSE

To evaluate the possible associations between AGER (rs1051993, rs2070600) and ALDH2 (rs671) gene polymorphisms with nonproliferative (NPDR) and proliferative (PDR) diabetic retinopathy, in a well-defined Greek population.

MATERIALS

66 NPDR patients and 57 PDR patients participated in our study, along with 156 age- and gender-matched healthy-control subjects (CL). All the participants underwent a complete ophthalmological examination, while clinical and demographic data were collected. Furthermore, they were genotyped for the studied polymorphisms.

RESULTS

No significant differences were detected among the studied groups regarding the participants' age and gender status. We found that the ALDH2 AA genotype was significantly more frequent in PDR patients than in CL (p = 0.014). Furthermore, between NPDR and PDR groups, the AGER rs1051993 GT and TT genotype frequencies were significantly elevated in PDR patients (p < 0.0001 and 0.04, respectively). Moreover, we demonstrated that the heterozygous GT genotype in DR patients is accompanied by 71.11 times higher risk of developing PDR (OR = 71.11: 95% CI- 4.14-1215.2), while the homozygous TT genotype is associated with 12.71 times elevated risk for PDR development (OR = 12.71: 95% CI- 0.63-254.1).

CONCLUSIONS

We documented that the ALDH2 AA and AGER rs1051993 GT and TT genotypes were observed significantly more frequently in PDR Greek diabetic patients. Our findings also support the genetic theory, suggesting that heritability is significantly implicated in the development of DR, providing additional evidence in the understanding of DR pathogenesis.

Genetic associated complications of type 2 Diabetes Mellitus: a review

According to the International Diabetes Federation, the number of adults (age of 20-79) being diagnosed with Diabetes Mellitus (DM) have increased from 285 million in year 2009 to 463 million in year 2019 which comprises of 95% Type 2 DM patient (T2DM). Research have claimed that genetic predisposition could be one of the factors causing T2DM complications. In addition, T2DMcomplications cause an incremental risk to mortality. Therefore, this article aims to discuss some complications of T2DM in and their genetic association. The complications that are discussed in this article are diabetic nephropathy, diabetes induced cardiovascular disease, diabetic neuropathy, Diabetic Foot Ulcer (DFU) and Alzheimer's disease. According to the information obtained, genes associated with diabetic nephropathy (DN) are gene GABRR1 and ELMO1 that cause injury to glomerular. Replication of genes FRMD3, CARS and MYO16/IRS2 shown to have link with DN. The increase of gene THBS2, NGAL, PIP, TRAF6 polymorphism, ICAM-1 encoded for rs5498 polymorphism and C667T increase susceptibility towards DN in T2DM patient. Genes associated with cardiovascular diseases are Adiponectin gene (ACRP30) and Apolipoprotein E (APOE) polymorphism gene with ξ2 allele. Haptoglobin (Hp) 1-1 genotype and Mitochondria Superoxide Dismutase 2 (SOD2) plays a role in cardiovascular events. As for genes related to diabetic neuropathy, Janus Kinase (JAK), mutation of SCN9A and TRPA1 gene and destruction of miRNA contribute to pathogenesis of diabetic neuropathy among T2DM patients. Expression of cytokine IL-6, IL-10, miR-146a are found to cause diabetic neuropathy. Besides, A1a16Va1 gene polymorphism, an oxidative stress influence was found as one of the gene factors. Diabetic retinopathy (DR) is believed to have association with Monocyte Chemoattractant Protein-1 (MCP-1) and Insulin-like Growth Factor 1 (IGF1). Over-expression of gene ENPP1, IL-6 pro-inflammatory cytokine, ARHGAP22's protein rs3844492 polymorphism and TLR4 heterozygous genotype are contributing to significant pathophysiological process causing DR, while research found increases level of UCP1 gene protects retina cells from oxidative stress. Diabetic Foot Ulcer (DFU) is manifested by slowing in reepithelialisation of keratinocyte, persistence wound inflammation and healing impairment. Reepithelialisation disturbance was caused by E2F3 gene, reduction of Tacl gene encoded substance P causing persistence inflammation while expression of MMp-9 polymorphism contributes to healing impairment. A decrease in HIF-1a gene expression leads to increased risk of pathogenesis, while downregulation of TLR2 increases severity of wound in DFU patients. SNPs alleles has been shown to have significant association between the genetic dispositions of T2DM and Alzheimer's disease (AD). The progression of AD can be due to the change in DNA methylation of CLOCK gene, followed with worsening of AD by APOE4 gene due to dyslipidaemia condition in T2DM patients. Insulin resistance is also a factor that contributes to pathogenesis of AD.

Monocyte chemoattractant protein-1 (MCP-1/CCL2) in diabetic retinopathy: latest evidence and clinical considerations

Diabetic retinopathy (DR) is considered as a diabetes-related complication that can render severe visual impairments and is also a risk factor for acquired blindness in both developed as well as developing countries. Through fibrovascular epiretinal membranes (ERMs), this condition can similarly lead to tractional retinal detachment. Laboratory efforts evaluating the DR pathogenesis can be provided by ocular vitreous fluid and ERMs resulting from vitrectomy. The clinical stages of DR are significantly associated with expression levels of certain chemokines, including monocyte chemotactic protein-1 (MCP-1) in the intraocular fluid. The MCP-1 is also a known potent chemotactic factor for monocytes and macrophages that can stimulate them to produce superoxide and other mediators. Following hyperglycemia, retinal pigmented epithelial (RPE) cells, endothelial cells, and Müller's glial cells are of utmost importance for MCP-1 production, and vitreous MCP-1 levels rise in patients with DR. Increased expression of the MCP-1 in the eyes can also play a significant role in the pathogenesis of DR. In this review, current clinical and laboratory progress achieved on the MCP-1 and the DR concerning neovascularization and inflammatory responses in vitreous and/or aqueous humor of DR patients was summarized. It was suggested that further exploration of the MCP-1/CCR2 axis association between clinical stages of DR and expression levels of inflammatory and angiogenic cytokines and chemokines, principally the MCP-1 might lead to potential therapies aiming at neutralizing antibodies and viral vectors.

The association between MCP-1, VEGF polymorphisms and their serum levels in patients with diabetic foot ulcer

The purpose of the present study was to investigate distribution of monocyte chemoattractant protein-1 (MCP-1) -2518A/G and vascular endothelial growth factor (VEGF) -634G/C polymorphisms in type 2 diabetes melitus patients (T2DM) presenting diabetic foot ulcer (DFU). Additionally, we evaluated the effects of these 2 polymorphisms on serum levels of MCP-1 and VEGF in the study population.Patients diagnosed with T2DM without or with DFU were recruited in the study. The distribution of MCP-1 -2518A/G and VEGF -634G/C polymorphisms was investigated by polymerase chain reaction-restriction fragment length polymorphism (PCR-RFLP). Enzyme-linked immunosorbent assay (ELISA) was applied to detect the protein levels of MCP-1 and VEGF. The comparisons of protein levels in DFU patients were performed by student t test according to their genotypes.The frequencies of GG genotype and G allele of MCP-1 -2518A/G was increased in DFU patients, compared with T2DM patients (odds ratio [OR] = 2.60, 95% confidence interval [CI] = 1.23-5.50, P = .011 and OR = 1.72, 95% CI = 1.18-2.50, P = .005, respectively). Moreover, the increased frequency of GG was significantly associated with up-regulated MCP-1 level in DFU patients (P < .001). Analysis for VEGF -634G/C polymorphisms indicated that the prevalence of CC genotype and C allele of the polymorphisms was decreased in DFU patients, compared with T2DM patients (OR = 0.36, 95% CI = 0.17-0.77, P = .008 and OR = 0.63, 95% CI = 0.43-0.91, P = .015, respectively). DFU patients carrying CC genotype had a higher level of VEGF than those with other genotypes (P = .007).MCP-1 -2518A/G and VEGF -634G/C polymorphisms may involve in occurrence and progress of DFU through regulating transcription activity of the genes.

Diabetic macular oedema: under-represented in the genetic analysis of diabetic retinopathy

Diabetic retinopathy, a complication of both type 1 and type 2 diabetes, is a complex disease and is one of the leading causes of blindness in adults worldwide. It can be divided into distinct subclasses, one of which is diabetic macular oedema. Diabetic macular oedema can occur at any time in diabetic retinopathy and is the most common cause of vision loss in patients with type 2 diabetes. The purpose of this review is to summarize the large number of genetic association studies that have been performed in cohorts of patients with type 2 diabetes and published in English-language journals up to February 2017. Many of these studies have produced positive associations with gene polymorphisms and diabetic retinopathy. However, this review highlights that within this large body of work, studies specifically addressing a genetic association with diabetic macular oedema, although present, are vastly under-represented. We also highlight that many of the studies have small patient numbers and that meta-analyses often inappropriately combine patient data sets. We conclude that there will continue to be conflicting results and no meaningful findings will be achieved if the historical approach of combining all diabetic retinopathy disease states within patient cohorts continues in future studies. This review also identifies several genes that would be interesting to analyse in large, well-defined cohorts of patients with diabetic macular oedema in future candidate gene association studies.

Diabetic macular oedema: clinical risk factors and emerging genetic influences

Diabetic macular oedema is the major cause of visual impairment in type 1 and type 2 diabetes. As type 2 diabetes becomes more prevalent worldwide, the prevalence of diabetic macular oedema is also expected to rise. Current management of diabetic macular oedema is challenging, expensive and not optimal in a subset of patients. Therefore, it is important to increase our understanding of the risk factors involved and develop preventative strategies. While clinical risk factors for diabetic macular oedema have been identified, few studies have addressed potential genetic risk factors. Epidemiology and family studies suggest genetic influences are of importance. In this review, we summarise known clinical risk factors, as well as discuss the small number of genetic studies that have been performed for diabetic macular oedema.

Association of increased levels of MCP-1 and cathepsin-D in young onset type 2 diabetes patients (T2DM-Y) with severity of diabetic retinopathy

AIM

Young onset type 2 diabetes patients (T2DM-Y) have been shown to possess an increased risk of developing microvascular complications particularly diabetic retinopathy. However, the molecular mechanisms are not clearly understood. In this study, we investigated the serum levels of monocyte chemotactic protein 1 (MCP-1) and cathepsin-D in patients with T2DM-Y without and with diabetic retinopathy.

METHODS

In this case-control study, participants comprised individuals with normal glucose tolerance (NGT=40), patients with type 2 diabetes mellitus (T2DM=35), non-proliferative diabetic retinopathy (NPDR=35) and proliferative diabetic retinopathy (PDR=35). Clinical characterization of the study subjects was done by standard procedures and MCP-1 and cathepsin-D were measured by ELISA.

RESULTS

Compared to control individuals, patients with T2DM-Y, NPDR and PDR exhibited significantly (p<0.001) higher levels of MCP-1. Cathepsin-D levels were also significantly (p<0.001) higher in patients with T2DM-Y without and with diabetic retinopathy. Correlation analysis revealed a positive association (p<0.001) between MCP-1 and cathepsin-D levels. There was also a significant negative correlation of MCP1/cathepsin-D with C-peptide levels. The association of increased levels of MCP-1/cathepsin-D in patients with DR persisted even after adjusting for all the confounding factors.

CONCLUSION

As both MCP-1 and cathepsin-D are molecular signatures of cellular senescence, we suggest that these biomarkers might be useful to predict the development of retinopathy in T2DM-Y patients.

Plasma miR-21 expression: an indicator for the severity of Type 2 diabetes with diabetic retinopathy

To investigate the roles of plasma miR-21 in the pathogenic process of Type 2 diabetes (T2D) with diabetic retinopathy (DR). T2D patients included patients without DR (NDR) group, patients with non-proliferative/background DR (BDR) group and patients with proliferative DR (PDR) group. Healthy individuals served as control group. Fasting plasma glucose (FPG), glycosylated haemoglobin (HbA1c), triacylglycerol (TG), total cholesterol (TC), urine creatinine (Cr), fasting blood glucose (FBG), blood urea nitrogen (BUN), low-density lipoprotein cholesterol (LDL-C), fasting insulin (FINS) and plasma miR-21 expression were measured. Quantitative real-time PCR (qRT-PCR) was applied to detect miR-21 expression. Pearson analysis was used to conduct correlation analysis and receiver operating characteristic (ROC) curve was used to analyse the diagnostic value of miR-21 in T2D with DR. Compared with the control group, FBG and HbA1c increased in the NDR group; compared with the control and NDR groups, disease course, HbA1c, FPG levels and homoeostasis model assessment of insulin resistance (HOMA-IR) were increased in the BDR and PDR groups; and compared with the BDR group, disease course, HbA1c and FPG levels were higher in the PDR group. miR-21 expression was higher in the BDR group than the control group, and higher in the PDR group than the BDR group. miR-21 expression was positively related with disease course, HbA1C, FPG and HOMA-IR, and had diagnostic value for T2D with DR and PDR. The plasma miR-21 expression was increased in the development of T2D with DR and can be used as an indicator for the severity of T2D with DR.

Mesenchymal stem cells: a future experimental exploration for recession of diabetic nephropathy

BACKGROUND

The progresses made in stem cell therapy offer an innovative approach and exhibit great potential for the repair of damaged organs and tissues. This study was conducted with a view to find the mechanisms responsible for the effectiveness of bone marrow-derived mesenchymal stem cells (BM-MSCs) in the suppression of diabetes and experimentally-induced diabetic nephropathy.

METHODS

To realize this objective, diabetic and diabetic nephropathy subject groups that underwent MSC treatment were studied through numerous biochemistry and molecular genetics analyses.

RESULTS

The findings show that, relative to the control groups, the rats in the diabetic and diabetic nephropathy groups treated with stem cells infused with BM-MSCs showed a significant reversal in the levels of their insulin, glucose, heme-oxygenase-1 (HO-1) serum, and advanced glycation end product (AGEP). Moreover, BM-MSC therapy was also found to have a definite positive effect on the kidney functions. In addition, it also corresponded with a significant decrease in the availability of certain growth factors, namely the fibroblast growth factor (FGF), the platelet-derived growth factor (PDGF), and the transforming growth factor-β (TGF-β). BM-MSC treatment also improved the levels of expression of monocyte chemoatractant-1 (MCP-1) and interleukin-8 (IL-8) genes within kidney tissues. Lastly, the treatment recovered the organizational structure of the kidney and pancreas, a result demonstrated by a histopathological analysis. These results greatly coincide with those obtained through the biochemistry and molecular genetics analyses.

CONCLUSION

Treatment using BM-MSCs is determined to be definitely effective in cases of diabetes and diabetic nephropathy.

Candidate gene studies of diabetic retinopathy in human

Diabetic retinopathy (DR) is a multifactorial disease with complex pathophysiology. It is the main cause of blindness among the people in productive age. The purpose of this literature review is to highlight recent achievements in the genetics of diabetic retinopathy with particular focus on candidate gene studies. We summarized most of the available published data about candidate genes for diabetic retinopathy with the goal to identify main genetic aspects. We conclude that genetic studies reported contradictory findings and no genetic variants meet criteria of a diagnostic marker, or significantly elucidate the root of DR development. Based on these findings it is important to continue with the research in the field of DR genetics, mainly due to the fact that currently new possibilities and approaches associated with utilization of next-generation sequencing are available.

Association of monocyte chemoattractant protein-1 gene 2518A/G polymorphism with diabetic retinopathy in type 2 diabetes mellitus: A meta-analysis

AIMS

The relationship between monocyte chemoattractant protein-1 (MCP-1) 2518 A/G polymorphism and diabetic retinopathy (DR) attracted intense interest recently, but the reported results are controversial. A meta-analysis was performed to assess the MCP-1 polymorphism associated with DR susceptibility in type 2 diabetes mellitus.

METHODS

Eligible studies were identified from PubMed, Embase, Web of science, Chinese Biomedical database, and references of retrieved articles. Pooled odds ratios (ORs) with their 95% confidence intervals (95%CI) were calculated by fixed or random-effects models.

RESULTS

Six studies involving 3415 patients without DR and 3468 with any DR were included in the final meta-analysis. Each 5 studies evaluated the associations of MCP-1 polymorphism and any DR and proliferative DR (PDR), respectively. Meta-analysis in fixed model demonstrated a significant association between MCP-1 polymorphism and any DR under the homozygous model (OR=1.36; 95%CI: 1.15-1.62, P<0.001), heterozygous model (OR=1.20; 95%CI: 1.02-1.42, P=0.031), dominant model (OR=1.28; 95%CI: 1.10-1.50, P=0.002), recessive model (OR=1.17; 95%CI: 1.05-1.31, P=0.004), and allelic model (OR=1.16; 95%CI: 1.07-1.25, P<0.001). Furthermore, a significant association of MCP-1 polymorphism and DR progression from non-proliferative DR to proliferative DR was identified under heterozygous model (OR=1.45; 95%CI: 1.04-2.02, P=0.030). Sensitivity analyses did not draw different findings.

CONCLUSIONS

Meta-analysis of existing data suggested that MCP-1 2518 A/G polymorphism affected the risk of presence and progression of DR in type 2 diabetes mellitus.

Elevated serum monocyte chemoattractant protein-1 levels and its genetic polymorphism is associated with diabetic retinopathy in Chinese patients with Type 2 diabetes

AIM

Previous studies have reported that monocyte chemoattractant protein-1 (MCP-1) is involved in inflammatory and metabolic diseases. The purpose of this study is to investigate the role of MCP-1 in the pathogenesis of diabetic retinopathy (DR) in Han Chinese patients with Type 2 diabetes.

METHODS

Serum levels of MCP-1 protein in patients classified as diabetic without retinopathy (DWR) and DR, including NPDR and PDR, were assayed by enzyme-linked immunosorbent assay. Genomic DNA from 198 DWR patients, 176 NPDR patients and 143 PDR patients were genotyped by using a PCR restriction fragment length polymorphism (PCR-RFLP) assay.

RESULTS

MCP-1 serum levels were significantly higher in NPDR and PDR patients than in the DWR patients. The frequencies of the GG genotype and G allele of the single nucleotide polymorphism (SNP) were significantly increased in DR patients compared with DWR patients. Further subgroup analysis was performed to test whether there was an association between the PDR or NPDR and DWR groups. Significantly higher frequencies of the GG genotype and G allele were observed in PDR and NPDR patients compared with DWR patients. Furthermore, the 25 patients with PDR were divided into three groups according to the genotype of the tested SNP. The expression of the MCP-1 gene was higher in the GG genotype group compared with the other two groups.

CONCLUSIONS

The results suggested that the -2518 GG genotype and G allele of MCP-1 are associated with an increased risk of PDR in the Chinese Han population. This polymorphism may influence the expression of the MCP-1 gene, which may play an important role in the pathogenesis of DR.

Update on genetics and diabetic retinopathy

Clinical risk factors for diabetic retinopathy (DR), such as duration of disease and degree of glucose control, do not adequately predict disease progression in individual patients, suggesting the presence of a genetic component. Multiple smaller studies have investigated genotype–phenotype correlations in genes encoding vascular endothelial growth factor, aldose reductase, the receptor for advanced glycation end products, and many others. In general, reported results have been conflicting, due to factors including small sample sizes, variations in study design, differences in clinical end points, and underlying genetic differences between study groups. At this time, there is no confirmed association with any risk allele reported. As we continue to collect data from additional studies, the role of genetics in DR may become more apparent.

Novel Therapies in Development for Diabetic Macular Edema

Diabetic macular edema (DME) secondary to diabetic retinopathy (DR) is a major cause for functional visual loss in the developed world. Laser photocoagulation has been used for decades in the treatment of DME. However, the advent of anti-vascular endothelial growth factor (anti-VEGF) has revolutionized the treatment of DME. Three important anti-VEGF agents whose efficacy has been well established via phase III clinical trials include ranibizumab, bevacizumab, and aflibercept. However, even in the era of anti-VEGF therapies, there are some challenges that retina specialists have to confront in managing patients with DME. These include the need for frequent treatment and an unpredictable response to therapy. There is evidence to suggest that pathways other than the VEGF pathway may be playing a role in the development of DME. Thus, extensive research is focused on development of novel agents that target these pathways. This review focuses on novel therapeutic agents in development, which may be used as a monotherapy or in combination with anti-VEGF agents, for the management of DME in the future.

Monocyte chemoattractant protein-1 (MCP-1) g.-2518A>G polymorphism and susceptibility to type 2 diabetes (T2D) and end stage renal disease (ESRD) in the North-West Indian population of Punjab

BACKGROUND

Diabetic nephropathy (DN) is a major microvascular complication that develops in nearly 20-30% of patients with type 2 diabetes (T2D) and is currently the leading cause of end stage renal disease (ESRD). Monocyte chemoattractant protein-1 (MCP-1), a potent chemokine secreted by adipocytes, has been implicated as a causal factor in the progression of vascular complications in T2D, thus MCP-1 appears to be a promising candidate for association study.

AIM

The objective of the present study is to evaluate the association, if any, of g.-2518A>G polymorphism (rs1024611) in MCP-1 gene in T2D cases with and without ESRD in the population of Punjab from North-West India.

SUBJECTS AND METHODS

A total of 571 samples from Punjab comprising 350 T2D cases (145 with ESRD and 205 without ESRD) and 221 controls were genotyped for g.-2518A>G MCP-1 polymorphism using amplification refractory mutation system- polymerase chain reaction.

RESULTS

The frequency of G allele was observed to be higher in T2D cases with ESRD (34.49%) compared to T2D cases without ESRD (24.39%) and controls (31.67%). Under the dominant model, G allele increased the risk of ESRD by 1.68-fold [p = 0.047, OR = 1.68 (1.0-2.79) at 95% CI].

CONCLUSION

MCP-1 -2518 GG genotype and G allele may increase the risk of progression to ESRD in T2D cases.

Association of monocyte chemoattractant protein-1 (MCP-1)2518A/G polymorphism with proliferative diabetic retinopathy in northern Chinese type 2 diabetes

BACKGROUND

The pathogenesis of proliferative diabetic retinopathy (PDR) remains poorly understood. Recent studies have implicated that monocyte chemoattractant protein-1 (MCP-1) is associated with diabetic microvascular or macrovascular complications. However, the relationship between single nucleotide polymorphism(SNP)c.2518A/G -rs1024611 in the MCP-1 gene with diabetic retinopathy remains controversial. In the present study, we evaluated the association of SNP in the MCP-1 gene with diabetic retinopathy (DR) and diabetic macular edema (DME) in a Chinese population from Northern China with type 2 diabetes.

METHODS

We conducted a case-control study, which enrolled 1,043 subjects with type 2 diabetes (528 with DR, including 277PDR; 515 without DR), and SNP genotyping of c.2518A/G in the MCP-1 gene was performed using the polymerase chain reaction. Genomic DNA was isolated from 3 ml samples of whole blood using a modified conventional DNA extraction method. The genotype and allele frequencies of 2518A/G were studied by using an automated DNA sequencer (ABI PRISM 3730 DNA Sequencer).

RESULTS

The demographic and clinical characteristics did not differ among genotype subgroups. The MCP-1(-2518) GG genotype was significantly associated with DR susceptibility with OR of 1.481 (95 % CI, 1.019-2.153) (P = 0.046). There were no significant differences in the MCP-1(-2518) G allele frequencies in DR compared to non-diabetic retinopathy (DNR) (P > 0.05, OR = 0.841, 95 % CI, 0.705-1.002). The MCP-1(-2518) GG genotype was significantly associated with high-risk PDR susceptibility with OR of 2.656 (95 % CI, 1.222-5.775) (P = 0.014). The MCP-1(-2518) G allele was significantly increased in high-risk PDR patients (P = 0.020, OR = 1.481, 95 % CI, 1.070-2.051) compared with A allele. Genotype and allele frequencies of various DME of the DR patients were compared, but there were no significant associations established (P > 0.05).

CONCLUSIONS

It is likely that the MCP-1 c.2518G/G genotype is a susceptibility gene for DR in Chinese type 2 diabetic patients, especially the high-risk PDR. There is no association with DME and c.2518G/G.

Developments in Ocular Genetics: 2013 Annual Review

PURPOSE

To highlight major advancements in ocular genetics from the year 2013.

DESIGN

Literature review.

METHODS

A literature search was conducted on PubMed to identify articles pertaining to genetic influences on human eye diseases. This review focuses on manuscripts published in print or online in the English language between January 1, 2013 and December 31, 2013. A total of 120 papers from 2013 were included in this review.

RESULTS

Significant progress has been made in our understanding of the genetic basis of a broad group of ocular disorders, including glaucoma, age-related macular degeneration, cataract, diabetic retinopathy, keratoconus, Fuchs' endothelial dystrophy, and refractive error.

CONCLUSIONS

The latest next-generation sequencing technologies have become extremely effective tools for identifying gene mutations associated with ocular disease. These technological advancements have also paved the way for utilization of genetic information in clinical practice, including disease diagnosis, prediction of treatment response and molecular interventions guided by gene-based knowledge.

Correlations of MCP-1 -2518A>G polymorphism and serum levels with cerebral infarction risk: a meta-analysis

This meta-analysis was performed to evaluate the relationships between the monocyte chemoattractant protein-1 (MCP-1) -2518A>G (rs1024611 A>G) polymorphism and its serum levels, and the risk of cerebral infarction. The PubMed, CISCOM, CINAHL, Web of Science, Google Scholar, EBSCO, Cochrane Library, and CBM databases were searched for relevant articles published before October 1st, 2013 without language restrictions. Meta-analysis was conducted using the STATA 12.0 software. Crude odds ratios (ORs) or standardized mean difference (SMD) with their 95% confidence intervals (95% CIs) were calculated. Twelve case-control studies that met all the inclusion criteria were included in this meta-analysis. A total of 1272 patients with cerebral infarction and 1210 healthy control subjects were involved in this meta-analysis. Our meta-analysis results reveal that the MCP-1 -2518A>G polymorphism might increase the risk of cerebral infarction (A allele vs. G allele: OR=1.37, 95% CI: 1.18-1.60, p<0.001; GA+AA vs. GG: OR=1.33, 95% CI: 1.09-1.62, p=0.005; respectively). Furthermore, cerebral infarction patients had higher levels of serum MCP-1 than did healthy control subjects (SMD=2.96, 95% CI: 2.00-3.92, p<0.001). Statistical analysis revealed no evidence of publication bias in this meta-analysis (all p>0.05). Our findings indicate that the MCP-1 -2518A>G polymorphism and serum MCP-1 levels may contribute to the development of cerebral infarction. Thus, the MCP-1 -2518A>G polymorphism and serum MCP-1 levels could be potential biomarkers for the early detection of cerebral infarction.

Candidate genes for proliferative diabetic retinopathy

Several candidate genes have been so far implicated in the pathogenesis of proliferative diabetic retinopathy (PDR) in subjects with type 2 diabetes. Since the principal pathogenetic mechanisms for diabetic retinopathy (DR) and PDR are different, the main pathogenetic mechanism in DR is increased vascular permeability, whereas in PDR the crucial pathogenetic mechanisms are fibrosis and neoangiogenesis. Due to that fact, different candidate genes are expected to be involved in the development of either DR or PDR. None of the candidate genes, however, can be fully and solely responsible for the development of PDR and for DR progression into PDR. Epigenetic mechanisms are expected to be involved in the pathogenesis of PDR as well. Gene polymorphisms responsible for PDR and epigenetic mechanisms responsible for PDR are reviewed in this paper.