Association of genetic variants in the receptor for advanced glycation end products gene with diabetic retinopathy: A meta-analysis

Recent Advances in Imaging Polypoidal Choroidal Vasculopathy with Swept-Source Optical Coherence Tomography Angiography

The gold standard for polypoidal choroidal vasculopathy (PCV) diagnosis is indocyanine green angiography (ICGA), but optical coherence tomography angiography (OCTA) has shown promise for PCV imaging in recent years. However, earlier generations of OCTA technology lacked the diagnostic efficacy to replace ICGA. Swept-source optical coherence tomography angiography (SS-OCTA), the latest generation of OCTA technology, has significantly improved penetrating ability, scanning speed, scanning range, and overall image quality compared with earlier generations of OCTA. SS-OCTA reveals a "tangled vasculature" pattern of polypoidal lesions (PLs), providing evidence that they are neovascular rather than aneurysmal structures. New choroidal biomarkers, such as the choriocapillaris flow void (FV), have been identified to explain the development of PCV lesions. Although no direct comparison between SS-OCTA and previous OCTA generations in terms of diagnostic capability has been performed, SS-OCTA has shown several advantages in differential diagnosis and monitoring early reactivation for PCV. These improvements make SS-OCTA a valuable tool for PCV diagnosis and follow-up, and it may become more important for this disease in the future. This review summarized recent advances in PCV morphology and structure, as well as the possible pathogenesis based on SS-OCTA findings. The value of SS-OCTA for PCV management is discussed, along with remaining issues, to provide an updated understanding of PCV and OCTA-guided management.

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.

Single nucleotide variants of receptor for advanced glycation end-products (AGER) gene: is it a new opening in the risk assessment of diabetic retinopathy?-a review

Background

Diabetic retinopathy (DR) is a common microvascular complication of diabetes. There is strong evidence suggesting that DR has an inheritable component. The interaction between advanced glycation end products (AGEs) and their receptor is integral in the pathogenesis of diabetic retinopathy and its various complications, retinopathy being one of them.

Overview and methodology

This review discusses the existing literature on the association between single nucleotide variants (SNV) of AGER gene and the risk of DR. It also discusses the current understanding of the AGE-AGER pathway in diabetic retinopathy. Through our article we have tried to consolidate all the available information about these SNVs associated with diabetic retinopathy in a succinct tabular form. Additionally, a current understanding of the AGE-AGER interaction and its deleterious effects on the cells of the retina has been discussed in detail to provide comprehensive information about the topic to the reader. A literature review was performed on PubMed, Cochrane Library, and Google Scholar for studies to find existing literature on the association between AGER gene SNVs and the risk, progression and severity of developing DR. This article will encourage scientific communication and discussion about possibly devising genetic markers for an important cause of blindness both in developed and developing countries, i.e., diabetic retinopathy.

Result

Based on genetic studies done in Indian and Chinese population G82S(rs2070600) was positively associated with Diabetic Retinopathy. Patients of diabetic retinopathy in Caucasian population had −T374A(rs1800624) polymorphism. + 20T/A was found to be associated with the disease in a study done in UK. Association with G1704T(rs184003) was seen in Chinese and Malaysian population. A Chinese study found its association with CYB242T. -T429C(rs1800625) SNV was not associated with DR in any of the studies. G2245A(rs55640627) was positively associated with the disease process in Malaysian population. It was not associated in Malaysian and Chinese population. Promoter variant rs1051993 has also been found to a susceptible SNV in the Chinese population.

Conclusion

While providing a comprehensive review of the existing information, we would like to emphasize on a large, multi-centric, trial with a much larger and varied population base to definitely determine these single nucleotide variants predisposing diabetic individuals.

Dysregulation of Receptor for Advanced Glycation End Products (RAGE) Expression as a Biomarker of Keratoconus

BACKGROUND

Because of the implications of Receptor for Advanced Glycation End Products (RAGE) in keratoconus (KC), we describe a differential expression of RAGE transcripts and proteins in corneal tissues and tears of KC and healthy patients.

METHODS

Using a case-controlled study, corneal epitheliums and tears of KC and healthy subjects were obtained during corneal collagen cross-linking and photorefractive keratectomy (PKR) and during usual consultations. Quantitative reverse transcription (RT-qPCR) and Western-Blot were performed to analyze RAGE transcripts and proteins' expression in corneal tissues and tears.

RESULTS

One hundred and six patients were included in this study. The characteristics of the patients were as follows: 56 KC (25 corneal epithelium and 31 tears) and 50 control subjects (25 corneal epithelium and 25 tears). Transcripts of RAGE, HMGB1, and S100 family ligands were quantified by RT-qPCR, identifying a significantly higher expression of RAGE and HMGB1 in the healthy group than in the KC group (p = 0.03 and 0.04, respectively). Western Blot showed a significantly higher fl-RAGE expression in KC corneal epithelium than control (p < 0.001) and lower s-RAGE expression in KC tears than control (p = 0.04).

CONCLUSIONS

Linked with the inflammatory process occurring in KC pathophysiology, we propose for the first time that the RAGE expression (total and truncated forms of receptor and ligands) in KC corneal tissues and tear samples provides viable biomarkers.

Genetics of Diabetic Retinopathy, a Leading Cause of Irreversible Blindness in the Industrialized World

Diabetic retinopathy (DR) is a chronic complication of diabetes and a leading cause of blindness in the industrialized world. Traditional risk factors, such as glycemic control and duration of diabetes, are unable to explain why some individuals remain protected while others progress to a more severe form of the disease. Differences are also observed in DR heritability as well as the response to anti-vascular endothelial growth factor (VEGF) treatment. This review discusses various aspects of genetics in DR to shed light on DR pathogenesis and treatment. First, we discuss the global burden of DR followed by a discussion on disease pathogenesis as well as the role genetics plays in the prevalence and progression of DR. Subsequently, we provide a review of studies related to DR’s genetic contribution, such as candidate gene studies, linkage studies, and genome-wide association studies (GWAS) as well as other clinical and meta-analysis studies that have identified putative candidate genes. With the advent of newer cutting-edge technologies, identifying the genetic components in DR has played an important role in understanding DR incidence, progression, and response to treatment, thereby developing newer therapeutic targets and therapies.

Association analysis of 374T/A (rs1800624) receptor for advanced glycation end-products (RAGE) gene polymorphism with diabetic retinopathy in Pakistani patients

OBJECTIVES

to determine the relationship of 374T/A (rs1800624) polymorphism in the gene encoding RAGE with Type-2 diabetes mellitus (T2DM), diabetic retinopathy (DR) and serum soluble RAGE (sRAGE) level in Pakistani patients.

METHODS

A case-control study, conducted from January 2017 to December 2018, involving 150 healthy controls (HC), 150 T2DM patients with no retinopathy (DNR) and 150 DR patients diagnosed by coloured fundus photography. Tetra-primer amplification refractory mutation system - polymerase chain reaction (T-ARMS-PCR) was used for genotyping. Serum sRAGE levels were measured by enzyme-linked immunosorbent assays (ELIZA).

RESULTS

The frequency of TT, TA and AA genotypes of rs1800624 polymorphism were: 92.7%, 6%, 1.3% in HC, 80%, 17.3%, 2.7% in DNR and 76.7%, 19.3%, 4.3% in DR groups. Heterozygous TA genotype and mutant A allele showed significant association with diabetes and DR vs HC. In dominant model, mutant allele showed significant association with DNR and DR vs HC. No significant association of rs1800624 was detected with DR and its sub-groups, non-proliferative DR (NPDR) and proliferative DR (PDR) vs DNR. Dividing NPDR into mild, moderate and severe, heterozygous TA genotype showed significant association with moderate and severe NPDR vs DNR. In DNR and DR groups, TA genotype was significantly associated with raised sRAGE.

CONCLUSION

rs1800624 RAGE gene polymorphism might be a risk factor for T2DM and NPDR in Pakistani patients. Raised sRAGE levels have a positive correlation with PDR and are associated with heterozygosity of rs1800624 polymorphism in DNR and DR groups.

Greater macrovascular and microvascular morbidity from type 2 diabetes in northern compared with southern China: A cross-sectional study

AIMS/INTRODUCTION

There are substantial differences in genes, diet, culture and environment between the northern and southern Chinese populations, which might influence treatment strategy and screening policy. We studied the differences in type 2 diabetes and diabetic complications between northern and southern China.

MATERIALS AND METHODS

We carried out a cross-sectional survey using data from the China Cardiometabolic Registries on blood pressure, blood lipids and blood glucose in 25,398 Chinese type 2 diabetes patients. Macrovascular, microvascular and other complications were collected by self-report or medical records, and then divided into the northern and southern groups by the boundary of the Yangtze River.

RESULTS

Northern patients were younger, and had heavier weight, greater body mass index and waist circumference, higher blood pressure, higher total cholesterol, higher low-density lipoprotein cholesterol, and higher hemoglobin A1C. The prevalence of cardiovascular, cerebrovascular and macrovascular complications were 1.76-fold, 1.24-fold and 1.47-fold more in northern than that in southern Chinese patients. In addition, the prevalence of diabetic nephropathy, retinopathy, neuropathy and microvascular complications in northern Chinese patients also increased. When stratified by age, the difference in both cardiovascular disease and ischemic stroke morbidity became significant, even in the 35-44 years age group.

CONCLUSIONS

More macrovascular and microvascular complications were found in northern compared with southern patients, and the largest difference also appeared in the younger age groups <55 years, which might be meaningful to a screening and treatment strategy according to geographic differences.

Association between diabetic retinopathy and interleukin-related gene polymorphisms: a machine learning aided meta-analysis

BACKGROUND

Diabetic retinopathy (DR) is a severe complication of diabetes and a common cause of visual loss in adults. We aimed to assess the correlation between IL gene-related SNPs and the incidence of DR and attempted to predict DR with combined mutation site detection.

METHODS

A systematic search of databases was performed up to August 2019. Five genetic models were used to analyze associations. Machine learning methods were implemented to improve SNP-related disease prediction.

RESULTS

Sixteen trials assessing a total of 7221 patients were included in our meta-analysis. IL6/rs1800795, rs1800796, and IL10/rs1800896 were analyzed. For the IL-6 gene, there was no significant association between rs1800795 and the incidence of DR (allelic model: OR, 1.091; 95% CI, 0.892-1.334; p = .396). There was no significant correlation between rs1800796 (allelic model: OR, 1.135; 95% CI, 0.678-1.901; p = .63), rs1800896 (allelic model: OR, 1.047; 95% CI, 0.788-1.392; p = .752) and the incidence of DR. Unfortunately, the machine learning results also showed that the combined detection of two SNPs could not accurately predict DR occurrence.

CONCLUSION

rs1800795 and rs1800796 in the IL-6 gene and rs1800896 in IL-10 gene are not related to the incidence of DR. Mutations in multiple SNPs for each DR patient still need to be specifically assessed to increase prediction accuracy.

Oxidative Stress as the Main Target in Diabetic Retinopathy Pathophysiology

Diabetic retinopathy (DR) is one of the most common complications of diabetes mellitus (DM) causing vision impairment even at young ages. There are numerous mechanisms involved in its development such as inflammation and cellular degeneration leading to endothelial and neural damage. These mechanisms are interlinked thus worsening the diabetic retinopathy outcome. In this review, we propose oxidative stress as the focus point of this complication onset.

Pathological Implications of Receptor for Advanced Glycation End-Product (AGER) Gene Polymorphism

The receptor for advanced glycation end-products (RAGE) is a cell surface transmembrane multiligand receptor, encoded by the AGER gene. RAGE presents many transcripts, is expressed mainly in the lung, and involves multiple pathways (such as NFκB, Akt, p38, and MAP kinases) that initiate and perpetuate an unfavorable proinflammatory state. Due to these numerous functional activities, RAGE is implicated in multiple diseases. AGER is a highly polymorphic gene, with polymorphisms or SNP (single-nucleotide polymorphism) that could be responsible or co-responsible for disease development. This review was designed to shed light on the pathological implications of AGER polymorphisms. Five polymorphisms are described: rs2070600, rs1800624, rs1800625, rs184003, and a 63 bp deletion. The rs2070600 SNP may be associated with the development of human autoimmune disease, diabetes complications, cancer, and lung diseases such as chronic obstructive pulmonary disease and acute respiratory distress syndrome. The rs1800624 SNP involves AGER gene regulation and may be related to reduced risk of heart disease, cancer, Crohn's disease, and type 1 diabetes complications. The rs1800625 SNP may be associated with the development of diabetic retinopathy, cancer, and lupus but may be protective against cardiovascular risk. The rs184003 SNP seems related to coronary artery disease, breast cancer, and diabetes. The 63 bp deletion may be associated with reduced survival from heart diseases during diabetic nephropathy. Here, these potential associations between AGER polymorphisms and the development of diseases are discussed, as there have been conflicting findings on the pathological impact of AGER SNPs in the literature. These contradictory results might be explained by distinct AGER SNP frequencies depending on ethnicity.