K469E polymorphism of the intracellular adhesion molecule 1 gene is associated with proliferative diabetic retinopathy in Caucasians with type 2 diabetes

The influence of ICAM1 rs5498 on diabetes mellitus risk: evidence from a meta-analysis

OBJECTIVES

Both type 1 diabetes (T1D) and type 2 diabetes (T2D) are classified as forms of diabetes mellitus (DM) and commonly considered inflammatory process. Intercellular adhesion molecule-1 (ICAM-1) is involved in the development and progression of diabetes mellitus. However, the genetic association between ICAM-1 rs5498, and T1D and T2D risk was inconclusive.

MATERIALS AND METHODS

A meta-analysis by searching the PubMed, Embase, Cochrane Library, and Chinese National Knowledge Infrastructure (CNKI) databases was performed out. The pooled odds ratio (OR) and 95% confidence interval (CI) were used to describe the strength of association of T1D and T2D risk.

RESULTS

A total of 14 studies encompassing 3233 cases and 2884 controls were included in the present meta-analysis. Significant associations were found between the allele and recessive models of ICAM1 rs5498 and DM in Asian population (allele: OR 1.13; 95% CI 1.03-1.23, p = 0.008; recessive: OR 1.25; 95% CI 1.06-1.48, p = 0.008), but not in Caucasian population (p > 0.05). In addition, the allele model of rs5498 was found to be significantly associated with the increased risk of T2D (OR 1.10; 95% CI 1.01-1.21, p = 0.03), but not T1D (p > 0.05).

CONCLUSIONS

The ICAM1 rs5498 might be a susceptible factor for T2D, but not T1D. And the allele and recessive models of ICAM1 rs5498 might be a risk factor in Asian population.

Association between diabetic retinopathy in type 2 diabetes and the ICAM-1 rs5498 polymorphism: a meta-analysis of case-control studies

Background

Genetic studies have reported contradictory results on the association between the intercellular adhesion molecule-1 (ICAM-1) rs5498 polymorphism and diabetic retinopathy (DR) risk in type 2 diabetic patients. We aimed to perform a systematic literature search and conduct random-effects meta-analysis to provide a quantitative evaluation.

Methods

We searched Pubmed, Embase, Scopus, Web of Science and Wanfang databases from inception up to January 2018. Allelic and genotype frequencies of rs5498 was compared between DR cases and controls. Odds ratios (OR) and 95% confidence intervals (CI) were calculated using a random effects model.

Results

Nine studies involving a total of 1792 cases and 1400 controls met our inclusion criteria. We did not find any significant association between rs5498 and DR risk at the dominant model (GG + GA versus AA, OR = 1.00, 95% CI: 0.66–1.50, P = 0.987), the recessive model (GG versus GA + AA, OR = 1.24, 95% CI: 0.86–1.77, P = 0.245), the GG versus AA contrast (OR = 1.14, 95% CI: 0.68–1.92, P = 0.611), and the G allele versus A allele contrast (OR = 1.08, 95% CI: 0.81–1.45, P = 0.592). Subgroup analysis by ethnicity showed no association in Asian populations (G allele versus A allele: OR = 1.05, 95% CI: 0.76–1.44, P = 0.790). Subgroup analysis by DR subtype also did not reveal any association of rs5498 with proliferative DR (G allele versus A allele: OR = 1.34, 95% CI: 0.71–2.52, P = 0.364) and non-proliferative DR (G allele versus A allele: OR = 0.71, 95% CI: 0.43–1.17, P = 0.180).

Conclusion

Our meta-analyses provide no evidence of the association of rs5498 with DR in type 2 diabetic patients.

Electronic supplementary material

The online version of this article (10.1186/s12886-018-0961-5) contains supplementary material, which is available to authorized users.

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.

Vascular endothelial growth factor (VEGF)-related single nucleotide polymorphisms rs10738760 and rs6921438 are not associated with diabetic retinopathy (DR) in Slovenian patients with type 2 diabetes mellitus (T2DM)

Diabetic retinopathy (DR) is a complication of diabetes characterized by vascular permeability, increased tissue ischemia, and angiogenesis. One of the most important proteins involved in angiogenesis is vascular endothelial growth factor (VEGF, also known as VEGFA). A previous study demonstrated that two single nucleotide polymorphisms (SNPs), rs6921438 and rs10738760, account for nearly half the variation in circulating VEGF levels. The aim of our study was to assess the association between rs6921438 and rs10738760 and DR in Slovenian patients with type 2 diabetes mellitus (T2DM). This case-control study enrolled 1037 unrelated Slovenian individuals (Caucasians) with T2DM. DR group included 415 T2DM patients with DR, while control group included 622 T2DM patients with no clinical signs of DR. The clinical and laboratory data were obtained from the medical records of the patients. The genotyping of rs6921438 and rs10738760 SNPs was carried out with real-time PCR assays. Significant differences were observed between patients with DR and controls in the duration of diabetes (p < 0.001), insulin therapy (p < 0.001), glycated hemoglobin (p = 0.001), body mass index (p = 0.002), total cholesterol (p = 0.002), and low-density lipoprotein cholesterol (p < 0.001). However, we did not observe significant differences in the genotype and allele distribution of the two SNPs, between DR and control group (p < 0.05). Logistic regression analysis showed that rs6921438 and rs10738760 were not independent genetic risk factors for DR in the co-dominant model adjusted for the above-mentioned clinical and laboratory data. In conclusion, VEGF-related SNPs rs10738760 and rs6921438 are not associated with DR in our group of Slovenian patients (Caucasians) with T2DM.

The ICAM-1 Gly241Arg Polymorphism is Not Associated With Polycystic Ovary Syndrome - Results from a Case Control study in Kashmir, India

BACKGROUND

Polycystic ovary syndrome (PCOS) is considered to be a multifactorial disorder resulting from the interaction of several predisposing and protective genetic variants. PCOS is associated with low-grade chronic inflammation. Elevated levels of inflammatory markers including intercellular adhesion molecule-1 (ICAM-1) are demonstrated in women with PCOS. Recent evidence indicates a significant linkage between a locus on chromosome 19p13 and multifactorial diseases that have an inflammatory component. The aim of the study was to assess the possible association of Gly241Arg polymorphism of ICAM-1 gene located on chromosome 19p13 in determining risk of PCOS in Kashmiri women.

MATERIALS AND METHODS

Gly241Arg SNP in DNA from peripheral blood leukocytes of 220 PCOS cases and 220 age matched non-PCOS healthy controls was analysed using allel specific PCR.

RESULTS

The genotype and allele frequency distributions of Gly241Arg SNP showed insignificant difference between the PCOS cases and control women, indicating no role of this SNP in PCOS susceptibility. The odds ratio for Arg/Arg genotype was 0.87 (95% CI=0.32-2.3) [P=0.79], for Gly/Arg genotype was 0.98 (95% CI= 0.66-1.47) [P=1] and for Arg/Arg+Gly/Arg genotype was 0.97 (95% CI=0.65-1.45) [P=0.92]. The genotypic frequencies of ICAM-1codon 241 showed statistically insignificant difference between cases and controls (χ2=0.07; p=0.96) Nor the studied polymorphism was found to affect clinical and laboratory parameters significantly.

CONCLUSIONS

Although Gly241Arg polymorphism have not shown significant association with PCOS. Further, specifically designed studies on large cohorts are required to conclusively establish any role of ICAM-1 gene polymorphisms in PCOS in our study.

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.

Polymorphism rs5498 of the ICAM-1 gene affects the progression of carotid atherosclerosis in patients with type 2 diabetes mellitus

Background

Adhesion molecules are involved in the development of atherosclerosis. An increased level of the ICAM 1 molecule is associated with numerous inflammatory diseases including atherosclerosis of carotid arteries. The rs5498 (K469E) polymorphism of the ICAM-1 gene leads to an increase in the level of serum ICAM. We investigated the association between the rs5498 (K469E) polymorphism of the ICAM-1 gene and the progression of carotid atherosclerosis in subjects with type 2 diabetes mellitus (T2DM).

Methods

The study included 595 patients with T2DM and 200 subjects in the control group without T2DM. The control examination was made 3.8 years after the initial examination. Indicators of atherosclerosis (carotid intima-media thickness (CIMT), total plaque sum and sum of the plaques thickness) were detected by ultrasound examination. Genetic analyses of the polymorphism rs5498 of the ICAM-1 gene were made by RT-PCR.

Results

The distribution of genotypes and frequencies of rs5498 polymorphism was not significantly different between the group with type 2 diabetes ( T2DM) and the control group. Genotype EE K469E polymorphism is associated with a statistically significant annual plaques growth.

Conclusion

The EE genotype of the rs5498 of the ICAM-1 gene was associated with a more rapid progression of carotid atherosclerosis in patients with T2DM in comparison with other genotypes.

Meta-analysis of association between K469E polymorphism of the ICAM-1 gene and retinopathy in type 2 diabetes

AIM

To collectively evaluate the association of intercellular adhesion molecule-1 (ICAM-1) gene K469E polymorphism (rs5498) with diabetic retinopathy (DR) in patients with type 2 diabetic mellitus (T2DM).

METHODS

Overall review of available literatures relating K469E polymorphism to the risk of DR was conducted on 4 electronic databases. Meta-analysis was performed by Stata 12.0 to calculate pooled odds ratios (ORs). Potential sources of heterogeneity and bias were explored.

RESULTS

Seven studies with genotype frequency data including 1120 cases with DR and 956 diabetic controls free of DR were included. Meta-analysis did not show significant association of K469E polymorphism with DR (P>0.05). A statistically significant association was detected between the K469E polymorphism and proliferative diabetic retinopathy (PDR) in Asians only in dominant model (GG+AG vs AA) with pooled OR of 0.729 (95%CI: 0.564-0.942, P=0.016, P heterogeneity=0.143), however, this association was not detected in recessive model (GA+AA vs GG; OR=1.178, 95%CI: 0.898-1.545, P=0.236, P heterogeneity=0.248) or allelic model (G vs A; OR=0.769, 95% CI: 0.576-1.026, P=0.074, P heterogeneity=0.094). No publication bias was found by Funnel plot, Begg's and Egger's test.

CONCLUSION

This research found no statistically significant association between ICAM-1 gene K469E polymorphism and DR in patients with T2DM, but showed significant association of the K469E polymorphism with PDR in Asian diabetic patients only in dominant model. Further investigation would be required to consolidate the conclusion.

Association between the ICAM-1 K469E polymorphism and diabetic retinopathy in Type 2 diabetes mellitus: a meta-analysis

A meta-analysis was conducted to evaluate the association of ICAM-1 K469E gene polymorphism with diabetic retinopathy susceptibility in Type 2 diabetes mellitus. Seven studies involving 1094 cases and 909 controls were included. Current studies suggest that K469E polymorphism in ICAM-1 gene might not affect individual susceptibility to DR.

KE and EE genotypes of ICAM-1 gene K469E polymorphism is associated with severe preeclampsia

BACKGROUND

Preeclampsia (PE) is one of the most important complications of pregnancy that is associated with significant mortality and morbidity in mother and fetus. Since the etiologic factors in its development are still unclear, we aimed to examine the intercellular adhesion molecule-1 (ICAM-1) gene K469E polymorphism in preeclamptic and control healthy women.

MATERIALS AND METHODS

Genetic polymorphism was analyzed in 192 PE and 186 healthy control women. PCR-RFLP method was used to identify K469E polymorphism.

RESULTS

The frequency of KK, KE, and EE genotypes of ICAM-1 gene was not different between PE patients and healthy pregnant women. Whereas, the frequency of KE and EE genotypes was significantly higher in severe PE than mild PE women and control group, and the risk of severe PE was 2.4-fold higher in subjects with KE genotype (OR, 2.4 [95% CI, 1 to 5.9]; P = 0.03) and 3.3-fold higher in subjects with EE genotype (OR, 3.3 [95% CI, 1.2 to 9]; P = 0.015) compared to individuals with KK genotype.

CONCLUSION

We concluded that KE and EE genotypes of K469E polymorphism could increase risk of severe PE.

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.

Intracellular adhesion molecule-1 K469E gene polymorphism and risk of diabetic microvascular complications: a meta-analysis

BACKGROUND

A number of studies evaluated the association of intracellular adhesion molecule-1 (ICAM-1) K469E (rs5498, A/G) gene polymorphism with diabetic microvascular complications (DMI) including diabetic nephropathy (DN) and diabetic retinopathy (DR) in different populations. However, the results of individual studies remain conflicting.

METHODS

A comprehensive search was conducted to identify all eligible studies of the above-mentioned associations. The pooled odds ratios (ORs) and 95% confidence intervals (CIs) were assessed using the fixed or random effect model.

RESULTS

Seven studies involving 3411 subjects were included. Overall, the meta-analysis showed a significant association of the A allele with increased risk of DMI susceptibility in a recessive model (OR = 1.37, 95% CI 1.04-1.80, P = 0.02). In the subgroup analysis stratified by ethnicity, significant association was found in Asians but not in Caucasians (OR = 1.78, 95% CI 1.13-2.81, P = 0.01; OR = 1.10, 95% CI 0.79-1.54, P = 0.58, respectively). Moreover, it showed a significant association between the A allele and risk of DN in a recessive model (OR = 1.25, 95% CI 1.02-1.55, P = 0.04).

CONCLUSIONS

This meta-analysis suggested that the K469E polymorphism in ICAM-1 gene might affect individual susceptibility to DMI and showed a discrepancy in different ethnicities. Further investigations are needed to validate the association.

Angiogenesis-related cytokines in serum of proliferative diabetic retinopathy patients before and after vitrectomy

AIM

To evaluate serum concentrations of angiogenesis-related cytokines in proliferative diabetic retinopathy (PDR) before and after vitrectomy.

METHODS

Serum samples were collected from 30 PDR patients with varying severity before and after vitrectomy. Serum concentrations of vascular endothelial growth factor (VEGF), pigment epithelium-derived factor (PEDF), interleukin-8 (IL-8) and interferon-inducible protein-10 (IP-10) were determined by enzyme-linked immunosorbent assays (ELISA).

RESULTS

Serum concentrations of VEGF, PEDF, IL-8 and IP-10 were significantly higher in PDR patients than that in controls, respectively (P<0.05). VEGF concentration decreased significantly in postoperative samples than that in preoperative samples (P<0.05). The concentrations of PEDF, IL-8 and IP-10 did not exhibit significant changes after vitrectomy.

CONCLUSION

Elevated cytokines levels in serum may be diagnostically useful in PDR. Angiogenesis-related cytokines play important roles in the development of PDR, and would instruct the risk assessment of pathogenetic condition in PDR patients.

Diabetic retinopathy and inflammation: novel therapeutic targets

Most anti-vascular endothelial growth factor (VEGF) therapies in diabetic macular edema are not as robust as in proliferative diabetic retinopathy. Although the VEGF appears to be a good target in diabetic macular edema, the anti-VEGF therapies appear to be of transient benefit as the edema recurs within a few weeks, and repeated injections are necessary. There is new evidence that indicates 'retinal inflammation' as an important player in the pathogenesis of diabetic retinopathy. There are common sets of inflammatory cytokines that are upregulated in both the serum and vitreous and aqueous samples, in subjects with diabetic retinopathy, and these cytokines can have multiple interactions to impact the pathogenesis of the disease. The key inflammatory events involved in the blood retinal barrier (BRB) alteration appear to be: (1) Increased expression of endothelial adhesion molecules such as ICAM1, VCAM1, PECAM-1, and P-selectin, (2) adhesion of leukocytes to the endothelium, (3) release of inflammatory chemokines, cytokines, and vascular permeability factors, (4) alteration of adherens and tight junctional proteins between the endothelial cells, and (5) infiltration of leukocytes into the neuro-retina, resulting in the alteration of the blood retinal barrier (diapedesis). VEGF inhibition itself may not achieve neutralization of other inflammatory molecules involved in the inflammatory cascade of the breakdown of the BRB. It is possible that the novel selective inhibitors of the inflammatory cascade (like angiopoietin-2, TNFα, and chemokines) may be useful therapeutic agents in the treatment of diabetic macular edema (DME), either alone or in combination with the anti-VEGF drugs.

The intercellular adhesion molecule-1 (ICAM-1) gene polymorphism K469E in end-stage renal disease patients with cardiovascular disease

The intercellular adhesion molecule-1 (ICAM-1) mediates interaction of activated endothelial cells with leukocytes. It plays an important role in the pathogenesis of atherosclerosis. A functionally important polymorphism of the ICAM-1 gene, K469E, has been described. We investigated whether this polymorphism influences the risk of CVD in end-stage renal disease (ESRD) patients. The groups of 1016 ESRD patients and 824 healthy individuals were genotyped by PCR and allele specific oligonucleotide technique. The T allele of the K469E polymorphism was significantly more frequent in ESRD CVD+ patients than CVD- and controls (OR 2.26, 95% CI 1.87-2.72 and 1.82, 95% CI 1.55-2.11, respectively). The TT genotype was also more frequent in CVD+ patients (OR 9.90, 95% CI 6.17-15.88 vs. CVD- subgroup). When patients were stratified according to clinical outcome of CVD, there was a tendency towards higher frequencies of the T allele and TT genotype in patients with myocardial infarction (OR for T allele 1, 57, 95% CI 1.12-2.18 vs. patients without MI). In the multivariate regression analysis the carrier status of T allele of K469E was an independent risk factor of susceptibility to CVD. Our data suggest that the ICAM-1 K469E polymorphism is associated with CVD in ESRD patients.

Chromosome 15q21-22-related polymorphisms and haplotypes are associated with susceptibility to type-2 diabetic nonproliferative retinopathy

OBJECTIVE

Diabetic retinopathy (DR) is a microvascular complication of diabetes with a complex multifactorial pathogenesis. We aimed to investigate whether chromosome 15q21-22-related gene polymorphisms could be used as markers of DR susceptibility in type 2 diabetic (T2D) individuals.

METHODS

Individuals were divided into three groups: (1) T2D with nonproliferative DR (NPDR; n=102); (2) T2D with proliferative DR (PDR; n=72); (3) T2D without DR (n=573). Six single-nucleotide polymorphisms (SNPs) (rs7174997, rs3751624, rs8025011, rs17818837, rs2922220, and rs2414520) lying within chromosome 15q21-22 region were genotyped by using Illumina HumanHap550-Duo BeadChips. Genotypes/allelic frequencies and haplotypes for these polymorphisms in each group were compared.

RESULTS

The MYO5C related SNP (rs3751624)*A related genotype and allele are associated with higher susceptibilities to DR, including PDR and NPDR. The rs3751624*GG/AA+AG percentages in each group are (1) 75.5%/24.5%, (2) 73.6%/26.4%, and (3) 82.5%/17.5%. In contrast, the other five SNPs in each group were not significantly different. One haplotype (G-A-G-G-T-G) appears significantly different between T2D individuals with and without DR. Other haplotype distributions were not significantly different between each group.

CONCLUSION

The MYO5C related SNP (rs3751624)*A related genotype/allele and haplotype (G-A-G-G-T-G) might be associated with susceptibility for retinopathy in T2D individuals. Some chromosome 15q21-22* related genetic variations might contribute to the pathogenesis of DR.

ICAM-1 K469E polymorphism is a genetic determinant for the clinical risk factors of T2D subjects with retinopathy in Indians: a population-based case-control study

OBJECTIVE

Elevated levels of intercellular adhesion molecule-1 (ICAM-1) are demonstrated in diabetes complications. The current study aims to understand association of K469E (rs5498) in ICAM-1 gene, in type 2 diabetic (T2D) subjects with retinopathy.

DESIGN

Case-control study.

SETTING

Sankara Nethralaya Diabetic Retinopathy Epidemiology and Molecular Genetic Study, an epidemiology study (on prevalence of diabetic retinopathy in T2D subjects (T2DR) from south India) and outpatient department of Sankara Nethralaya, a tertiary care hospital, in Chennai, India.

PARTICIPANTS

A total of 356 T2D subjects of >15 years of diabetes duration, with (n=199) and without (n=157) retinopathy.

METHODS

The rs5498 polymorphism was genotyped by direct sequencing. Multivariate analysis for various clinical covariates was done using SPSS V.14. Comparative assessment of structure stability, folding rate of the variants were assessed using bioinformatics tools like STRIDE, MuPro, ModellerV97, fold rate server, etc.

RESULTS

The AA genotype of rs5498 was seen at a higher frequency in the retinopathy group (p=0.012). The risk for diabetic retinopathy (DR) increased in the presence of AA genotype (OR=1.89-4.82) after the sequential addition of various clinical covariates. Multivariate logistic regression analysis showed 8.26 times high risk for developing DR in the AG genotype (p=0.003). Structural superimposition of ICAM-1 wild type (K469) and variant (E469) showed 0.943 Å of backbone root mean square deviation as calculated by PYMOL software. A difference in the fold rate time was also observed between the wild type (5.4/s) and variant (3.3/s).

CONCLUSIONS

This study shows that allele A of rs5498 in ICAM-1 is a putative risk predisposing allele for T2D retinopathy and its clinical covariates in Indian population. The folding rate of the protein decreases for the A allele implicating a potential effect on the structure and function of ICAM-1.

Association of intercellular adhesion molecule 1 (ICAM1) with diabetes and diabetic nephropathy

Diabetes and diabetic nephropathy are complex diseases affected by genetic and environmental factors. Identification of the susceptibility genes and investigation of their roles may provide useful information for better understanding of the pathogenesis and for developing novel therapeutic approaches. Intercellular adhesion molecule 1 (ICAM1) is a cell surface glycoprotein expressed on endothelial cells and leukocytes in the immune system. The ICAM1 gene is located on chromosome 19p13 within the linkage region of diabetes. In the recent years, accumulating reports have implicated that genetic polymorphisms in the ICAM1 gene are associated with diabetes and diabetic nephropathy. Serum ICAM1 levels in diabetes patients and the icam1 gene expression in kidney tissues of diabetic animals are increased compared to the controls. Therefore, ICAM1 may play a role in the development of diabetes and diabetic nephropathy. In this review, we present genomic structure, variation, and regulation of the ICAM1 gene, summarized genetic and biological studies of this gene in diabetes and diabetic nephropathy and discussed about the potential application using ICAM1 as a biomarker and target for prediction and treatment of diabetes and diabetic nephropathy.

Anti-inflammatory therapy for diabetic retinopathy

Diabetic retinopathy (DR) is one of the most common complications of diabetes. This devastating disease is a leading cause of blindness in people of working age in industrialized countries and affects the daily lives of millions of people. Despite tight glycemic control, blood pressure control and lipid-lowering therapy, the number of DR patients keeps growing and therapeutic approaches are limited. Moreover, there are significant limitations and side effects associated with the current therapies. Thus, there is a great need for development of new strategies for prevention and treatment of DR. Studies have shown that DR has prominent features of chronic, subclinical inflammation. This article focuses on the role of inflammation in DR and summarizes the progress of studies of anti-inflammatory strategies for DR.

Polymorphisms of interleukin-4, -10 and 12B genes and diabetic retinopathy

In diabetic retinopathy (DR) and other angiogenesis-associated diseases, increased levels of cytokines, inflammatory cells, and angiogenic factors are present. We investigated the hypothesis that rs2243250 polymorphism of the interleukin 4 (IL-4) gene or rs1800896 polymorphism of the interleukin 10 (IL-10) gene, and rs3212227 polymorphism of the 3’ untranslated region (3’ UTR) of the interleukin-12 p40 gene (IL12B) may be associated with the development of proliferative diabetic retinopathy (PDR) in Caucasians with type 2 diabetes (DM2). This cross sectional case — control study included 189 patients with PDR and 187 patients with type 2 diabetes without PDR. Polymorphisms rs1800896 of the IL-10 gene, rs2243250 of the IL-4 gene, and rs3212227 of IL12B gene were analyzed by ARMS -PCR and RFLP -PCR methods. Multivariate analysis demonstrated the GG genotype of the rs1800896 polymorphism of the IL-10 gene to be associated with increased risk for PDR (OR=1.99; 95% CI=1.11–3.57; P=0.02), whereas the TT genotype of the rs2243250 polymorphism of the IL-4 gene and the AA genotype of the rs3212227 polymorphism of the IL-12 gene were not independent risk factors for PDR. Our findings suggest that the genetic variations at the IL-10 promoter gene might be a genetic risk factor for PDR in Caucasians with type 2 diabetes.

Lack of association between intercellular adhesion molecule-1 (ICAM-1) polymorphisms and polycystic ovary syndrome

PURPOSE

This study examined the possible association of G241R and K469E single nucleotide polymorphisms (SNPs) of ICAM-1 gene with the occurrence and clinical/biochemical characteristics of polycystic ovary syndrome (PCOS).

METHODS

G241R and K469E SNPs in DNA from peripheral blood leukocytes of 169 PCOS and 259 healthy control women were investigated by real-time PCR combined with melting curve analysis using fluorescence-labeled hybridization probes.

RESULTS

We did not find significant differences in the distributions of G241R and K469E polymorphisms, nor in the haplotype frequencies between PCOS and control women. None of the studied polymorphisms were found to affect insulin resistance indices significantly.

CONCLUSIONS

These preliminary results suggest that the 241 and 469 SNPs of ICAM-1 gene may not be risk factors for PCOS. Further studies with a larger cohort, analyzing other ICAM-1 polymorphisms are necessary to support our observations before any statement can be made about the relationship between PCOS and ICAM-1 polymorphisms.

Inhibition of high glucose-induced VEGF and ICAM-1 expression in human retinal pigment epithelium cells by targeting ILK with small interference RNA

The aim of this study was to investigate the change of Integrin-linked kinase (ILK) expression of human retinal pigment epithelium (RPE) cells in response to high glucose, and the effect of targeting ILK with small interference RNA (siRNA) on the high glucose-induced expression of vascular endothelial growth factor (VEGF) and intercellular adhesion molecule-1 (ICAM-1). The ILK mRNA and protein expression in human RPE cells were analyzed with RT-PCR and western blot after exposure to 5.5, 30, 40, 50 mM glucose, or 5.5 mM glucose+45.5 mM mannitol for 48 h. The expression of VEGF and ICAM-1 was also determined. Cells were treated with ILK siRNA, to determine the effect of ILK on VEGF and ICAM-1 expression following treatment with high glucose. High concentrations of glucose significantly up-regulated ILK mRNA and protein expression, and the ILK expression increased along with the glucose concentration. The changes of VEGF and ICAM-1 expression were similar to that of ILK expression. Knocking down ILK gene expression with siRNA inhibited the elevation of VEGF and ICAM-1 induced by high glucose treatment. These results suggested that ILK was involved in the response of RPE cells to high glucose and may therefore play a role in the pathogenesis of diabetic ophthalmology.