Background Diabetic Retinopathy Research Articles

The association of chronic complications with time in tight range and time in range in people with type 1 diabetes: a retrospective cross-sectional real-world study.

The aim of this study was to evaluate the association of chronic complications with time in tight range (TITR: 3.9-7.8 mmol/l) and time in range (TIR: 3.9-10.0 mmol/l) in people with type 1 diabetes. The prevalence of microvascular complications (diabetic retinopathy, diabetic nephropathy and diabetic peripheral neuropathy [DPN]) and macrovascular complications according to sensor-measured TITR/TIR was analysed cross-sectionally in 808 adults with type 1 diabetes. Binary logistic regression was used to evaluate the association between TITR/TIR and the presence of complications without adjustment, with adjustment for HbA1c, and with adjustment for HbA1c and other confounding factors (sex, age, diabetes duration, BMI, BP, lipid profile, smoking, and use of statins and renin-angiotensin-aldosterone system inhibitors). The mean TITR and TIR were 33.9 ± 12.8% and 52.5 ± 15.0%, respectively. Overall, 46.0% had any microvascular complication (34.5% diabetic retinopathy, 23.8% diabetic nephropathy, 16.0% DPN) and 16.3% suffered from any macrovascular complication. The prevalence of any microvascular complication, diabetic retinopathy, diabetic nephropathy and a cerebrovascular accident (CVA) decreased with increasing TITR/TIR quartiles (all ptrend<0.05). Each 10% increase in TITR was associated with a lower incidence of any microvascular complication (OR 0.762; 95% CI 0.679, 0.855; p<0.001), diabetic retinopathy (OR 0.757; 95% CI 0.670, 0.856; p<0.001), background diabetic retinopathy (OR 0.760; 95% CI 0.655, 0.882; p<0.001), severe diabetic retinopathy (OR 0.854; 95% CI 0.731, 0.998; p=0.048), diabetic nephropathy (OR 0.799; 95% CI 0.699, 0.915; p<0.001), DPN (OR 0.837; 95% CI 0.717, 0.977; p=0.026) and CVA (OR 0.651; 95% CI 0.470, 0.902; p=0.010). The independent association of TITR with any microvascular complication (OR 0.867; 95% CI 0.762, 0.988; p=0.032), diabetic retinopathy (OR 0.837; 95% CI 0.731, 0.959; p=0.010), background diabetic retinopathy (OR 0.831; 95% CI 0.705, 0.979; p=0.027) and CVA (OR 0.619; 95% CI 0.426, 0.899; p=0.012) persisted after adjustment for HbA1c. Similar results were obtained when controlling for HbA1c and other confounding factors. TITR and TIR are inversely associated with the presence of microvascular complications and CVA in people with type 1 diabetes. Although this study was not designed to establish a causal relationship, this analysis adds validity to the use of TITR and TIR as key measures in glycaemic management. ClinicalTrials.gov NCT02601729 and NCT02898714.

NSUN2 affects diabetic retinopathy progression by regulating MUC1 expression through RNA m5C methylation

BackgroundDiabetic retinopathy (DR) is the leading cause of blinding eye disease among working adults and is primarily attributed to the excessive proliferation of microvessels, which leads to vitreous hemorrhage and retinal traction, thereby significantly impairing patient vision. NSUN2-mediated RNA m5C methylation is implicated in various diseases, and in this investigation, we focused on elucidating the impact of NSUN2 on the regulation of the expression of the downstream gene MUC1, specifically through RNA m5C methylation, on the progression of DR.MethodUtilizing Microarray analysis, we examined patient vitreous fluid to pinpoint potential therapeutic targets for DR. Differential expression of NSUN2 was validated through qRT-PCR, Western blot, and immunofluorescence in human tissue, animal tissue, and cell model of DR. The relationship between NSUN2 and DR was explored in vitro and in vivo through gene knockdown and overexpression. Various techniques, such as MeRIP-qPCR and dot blot, were applied to reveal the downstream targets and mechanism of action of NSUN2.ResultsThe levels of both NSUN2 and RNA m5C methylation were significantly elevated in the DR model. Knockdown of NSUN2 mitigated DR lesion formation both in vitro and in vivo. Mechanistically, NSUN2 promoted MUC1 expression by binding to the RNA m5C reader ALYREF. Knockdown of ALYREF resulted in DR lesion alterations similar to those observed with NSUN2 knockdown. Moreover, MUC1 overexpression successfully reversed a series of DR alterations induced by NSUN2 silencing.ConclusionsNSUN2 regulates the expression of MUC1 through ALYREF-mediated RNA m5C methylation, thereby regulating the progression of DR and providing a new option for the treatment of DR in the future.

Nerolidol Alleviates Oxidative Stress and Inflammation in Diabetic Retinopathy Mediated by High Glucose Through Ameliorating Nrf2/HO-1 Pathway

Background Diabetic retinopathy (DR) is the foremost microvascular problem that causes drastic visual impairment in diabetes patients. Hyperglycemia-triggered reaction cascade of inflammation and oxidative stress constitute the DR pathogenesis. The existing treatment options are not completely satisfactory. Materials and Methods We investigated the cell viability by 3-[4,5-dimethylthiazol-2-yl]-2,5 diphenyl tetrazolium bromide (MTT) assay, inflammatory mediators, lactate dehydrogenase (LDH), superoxide dismutase, glutathione, and malonaldehyde (MDA) levels by ELISA and qRT-PCR assay, protein expression of Nrf2 and heme oxygenase-1 (HO-1) by western blotting assay were analyzed. Results According to our research, nerolidol (NRD) increases the proliferation and antioxidant activity of human retinal endothelial cells (HRECs) by inducing Nrf2/HO-1 signaling, while attenuating MDA, an oxidative stress marker, LDH, and inflammatory mediators. These outcomes suggest that a substantial reaction of inflammation and oxidative stress injury happened in DR, which might be correlated to the instigation of the signaling Nrf2/HO-1. Conclusion NRD effectively suppresses oxidative stress and inflammation in HG-induced HRECs. The primary mechanism of NRD on DR may be linked to the activation of the Nrf2/HO-1 pathway and may give a useful medicine for DR treatment.

Cellular communication network factor 1 promotes retinal leakage in diabetic retinopathy via inducing neutrophil stasis and neutrophil extracellular traps extrusion

BackgroundDiabetic retinopathy (DR) is a major cause of blindness and is characterized by dysfunction of the retinal microvasculature. Neutrophil stasis, resulting in retinal inflammation and the occlusion of retinal microvessels, is a key mechanism driving DR. These plugging neutrophils subsequently release neutrophil extracellular traps (NETs), which further disrupts the retinal vasculature. Nevertheless, the primary catalyst for NETs extrusion in the retinal microenvironment under diabetic conditions remains unidentified. In recent studies, cellular communication network factor 1 (CCN1) has emerged as a central molecule modulating inflammation in pathological settings. Additionally, our previous research has shed light on the pathogenic role of CCN1 in maintaining endothelial integrity. However, the precise role of CCN1 in microvascular occlusion and its potential interaction with neutrophils in diabetic retinopathy have not yet been investigated.MethodsWe first examined the circulating level of CCN1 and NETs in our study cohort and analyzed related clinical parameters. To further evaluate the effects of CCN1 in vivo, we used recombinant CCN1 protein and CCN1 overexpression for gain-of-function, and CCN1 knockdown for loss-of-function by intravitreal injection in diabetic mice. The underlying mechanisms were further validated on human and mouse primary neutrophils and dHL60 cells.ResultsWe detected increases in CCN1 and neutrophil elastase in the plasma of DR patients and the retinas of diabetic mice. CCN1 gain-of-function in the retina resulted in neutrophil stasis, NETs extrusion, capillary degeneration, and retinal leakage. Pre-treatment with DNase I to reduce NETs effectively eliminated CCN1-induced retinal leakage. Notably, both CCN1 knockdown and DNase I treatment rescued the retinal leakage in the context of diabetes. In vitro, CCN1 promoted adherence, migration, and NETs extrusion of neutrophils.ConclusionIn this study, we uncover that CCN1 contributed to retinal inflammation, vessel occlusion and leakage by recruiting neutrophils and triggering NETs extrusion under diabetic conditions. Notably, manipulating CCN1 was able to hold therapeutic promise for the treatment of diabetic retinopathy.

Comparison of 21 artificial intelligence algorithms in automated diabetic retinopathy screening using handheld fundus camera

Background Diabetic retinopathy (DR) is a common complication of diabetes and may lead to irreversible visual loss. Efficient screening and improved treatment of both diabetes and DR have amended visual prognosis for DR. The number of patients with diabetes is increasing and telemedicine, mobile handheld devices and automated solutions may alleviate the burden for healthcare. We compared the performance of 21 artificial intelligence (AI) algorithms for referable DR screening in datasets taken by handheld Optomed Aurora fundus camera in a real-world setting. Patients and methods Prospective study of 156 patients (312 eyes) attending DR screening and follow-up. Both papilla- and macula-centred 50° fundus images were taken from each eye. DR was graded by experienced ophthalmologists and 21 AI algorithms. Results Most eyes, 183 out of 312 (58.7%), had no DR and mild NPDR was noted in 21 (6.7%) of the eyes. Moderate NPDR was detected in 66 (21.2%) of the eyes, severe NPDR in 1 (0.3%), and PDR in 41 (13.1%) composing a group of 34.6% of eyes with referable DR. The AI algorithms achieved a mean agreement of 79.4% for referable DR, but the results varied from 49.4% to 92.3%. The mean sensitivity for referable DR was 77.5% (95% CI 69.1–85.8) and specificity 80.6% (95% CI 72.1–89.2). The rate for images ungradable by AI varied from 0% to 28.2% (mean 1.9%). Nineteen out of 21 (90.5%) AI algorithms resulted in grading for DR at least in 98% of the images. Conclusions Fundus images captured with Optomed Aurora were suitable for DR screening. The performance of the AI algorithms varied considerably emphasizing the need for external validation of screening algorithms in real-world settings before their clinical application.

Evaluation of bi-directional causal association between obstructive sleep apnoea syndrome and diabetic microangiopathy: a Mendelian randomization study.

The relationship between obstructive sleep apnea syndrome (OSAS) and diabetic microangiopathy remains controversial. This study aimed to use bidirectional two-sample Mendelian Randomization (MR) to assess the causal relationship between OSAS and diabetic microangiopathy. First, we used the Linkage Disequilibrium Score Regression(LDSC) analysis to assess the genetic correlation. Then, the bidirectional two-sample MR study was conducted in two stages: OSAS and lung function-related indicators (forced vital capacity (FVC) and forced expiratory volume in 1 s (FEV1)) were investigated as exposures, with diabetic microangiopathy as the outcome in the first stage, and genetic tools were used as proxy variables for OSAS and lung function-related measures in the second step. Genome-wide association study data came from the open GWAS database. We used Inverse-Variance Weighted (IVW), MR-Egger regression, Weighted median, Simple mode, and Weighted mode for effect estimation and pleiotropy testing. We also performed sensitivity analyses to test the robustness of the results. Furthermore, we performed multivariate and mediation MR analyses. In the LDSC analysis, We found a genetic correlation between OSAS, FVC, FEV 1, and diabetic microangiopathy. In the MR analysis, based on IVW analysis, genetically predicted OSAS was positively correlated with the incidence of diabetic retinopathy (DR), diabetic kidney disease (DKD), and diabetic neuropathy (DN). In the subgroup analysis of DR, there was a significant causal relationship between OSAS and background diabetic retinopathy (BDR) and proliferative diabetic retinopathy (PDR). The reverse MR did not show a correlation between the incidence of diabetic microangiopathy and OSAS. Reduced FVC had a potential causal relationship with increased incidence of DR and PDR. Reduced FEV1 had a potential causal relationship with the increased incidence of BDR, PDR, and DKD. Multivariate MR analysis showed that the association between OSAS and diabetic microangiopathy remained significant after adjusting for confounding factors. However, we did not find the significant mediating factors. Our results suggest that OSAS may be a cause of the development of diabetic microangiopathy, and OSAS may also be associated with a high risk of diabetic microangiopathy, providing a reference for a better understanding of the prevention of diabetic microangiopathy.

Berberine alleviates diabetic retinopathy by regulating the Th17/Treg ratio

BackgroundDiabetic retinopathy (DR) stands as a prominent complication of diabetes. Berberine (BBR) has reported to be effective to ameliorate the retinal damage of DR. Studying the potential immunological mechanisms of BBR on the streptozotocin (STZ) induced DR mouse model will explain the therapeutic mechanisms of BBR and provide theoretical basis for the clinical application of this drug. MethodsC57BL/6 J mice were induced into a diabetic state using a 50 mg/(kg·d) dose of STZ over a 5-day period. Subsequently, they were subjected to a high-fat diet (HFD) for one month. Following a 5-week treatment with 100 mg/(kg·d) BBR, the concentrations of inflammatory factors in the mice's peripheral blood were determined using an enzyme-linked immunosorbent assay (ELISA). Hematoxylin-eosin staining was employed to scrutinize pathological changes in the mice's retinas, while flow cytometry assessed the proportions of T-lymphocyte subsets and the activation status of dendritic cells (DCs) in the spleen and lymph nodes. CD4+T cells and DC2.4 cell lines were utilized to investigate the direct and indirect effects of BBR on T cells under high glucose conditions in vitro. ResultsFollowing 5 weeks of BBR treatment in the streptozotocin (STZ) mouse model of DR, we observed alleviation of retinal lesions and a down-regulation in the secretion of inflammatory cytokines, namely TNF-α, IL-1β, and IL-6, in the serum of these mice. And in the spleen and lymph nodes of these mice, BBR inhibited the proportion of Th17 cells and promoted the proportion of Treg cells, thereby down-regulating the Th17/Treg ratio. Additionally, in vitro experiments, BBR directly inhibited the expression of the transcription factor RORγt and promoted the expression of the transcription factor Foxp3 in T cells, resulting in a down-regulation of the Th17/Treg ratio. Furthermore, BBR indirectly modulated the Th17/Treg ratio by suppressing the secretion of TNF-α, IL-1β, and IL-6 by DCs and enhancing the secretion of indoleamine 2,3-dioxygenase (IDO) and transforming growth factor-beta (TGF-β) by DCs. This dual action inhibited Th17 cell differentiation while promoting Treg cells. ConclusionOur findings indicate that BBR regulate T cell subpopulation differentiation, reducing the Th17/Treg ratio by directly or indirectly pathway. This represents a potential therapeutic avenue of BBR for improving diabetic retinopathy.

Observation on the changes of visual field and optic nerve fiber layer thickness in patients with early diabetic retinopathy

BackgroundDiabetic retinopathy (DR) is a common complication of diabetes mellitus (DM) and is a leading cause of vision loss. Early detection of DR-related neurodegenerative changes is crucial for effective management and prevention of vision loss in diabetic patients. MethodsIn this study, we employed spectral-domain polarization-sensitive optical coherence tomography (SD PS-OCT) to assess retinal nerve fiber layer (RNFL) changes in 120 eyes from 60 types 1 DM patients without clinical DR and 60 age-matched healthy controls. Visual field testing was performed to evaluate mean sensitivity (MS) and mean defect (MD) as indicators of visual function. ResultsSD PS-OCT measurements revealed significant reductions in RNFL birefringence, retardation, and thickness in type 1 DM patients compared to healthy controls. Visual field testing showed decreased MS and increased MD in DM patients, indicating functional impairment correlated with RNFL alterations. ConclusionOur findings demonstrate early neurodegenerative changes in the RNFL of type 1 DM patients without clinical DR, highlighting the potential of SD PS-OCT as a sensitive tool for early detection of subclinical DR-related neurodegeneration. These results underscore the importance of regular ophthalmic screenings in diabetic patients to enable timely intervention and prevent vision-threatening complications.

Evaluation of nail fold capillaroscopy changes in patients with diabetic retinopathy and healthy controls, and its correlation with disease duration, HbA1c levels and severity of diabetic retinopathy: An observational study

Background Diabetic retinopathy (DR) is an important microvascular complication of long-term type 2 diabetes mellitus (T2DM) leading to blindness if not properly diagnosed and managed. It can develop as early as 7 years before the diagnosis of diabetes. Nail fold capillaroscopy (NFC) is a non-invasive technique for observing capillary microvasculature and there are few studies which have explored the use of NFC in diabetes mellitus patients. Objective To study the nail fold capillaroscopic alterations in patients with T2DM having diabetic retinopathy and compare them to healthy controls. The secondary objective was to correlate the NFC findings with the duration of diabetes, haemoglobin A1c (HbA1c) levels and the severity of DR. Materials and methods This cross-sectional observational study enrolled 200 patients - 100 cases with T2DM having diabetic retinopathy (as per the American Diabetes Association criteria and Diabetic Retinopathy Disease Severity Scale) and 100 healthy age and sex-matched controls. All patients were subjected to NFC and ophthalmological assessment. Results NFC revealed that patients with DR showed significantly higher frequencies of tortuous, dilated, bushy, meandering, angulated capillaries, avascular areas and micro-haemorrhages as compared to healthy controls (p &lt; 0.05). In proliferative DR (PDR), the frequency of tortuous, bushy capillaries, and avascular areas was statistically high and the capillary density was reduced as compared to non-proliferative DR. The DR patients with longer disease duration (&gt;20) years had a significantly higher frequency of tortuous capillaries, avascular areas, meandering, angulated and dilated capillaries. The frequency of tortuosity, avascular areas, and bushy areas was significantly higher in patients with poor glycaemic control (HbA1c &gt;11). Limitations A larger sample size study with different demographic populations could have provided a broader picture of NFC changes in T2DM patients with DR. Discussion NFC may act as a surrogate marker of retinal involvement in patients with DM and should be performed at regular intervals. Conclusion NFC is a quick, simple, safe, and non-invasive method to assess the capillaroscopic alterations in diabetic patients which inturn can help in assessing the severity of DR.

Artificial intelligence based glaucoma and diabetic retinopathy detection using MATLAB — retrained AlexNet convolutional neural network

Background Glaucoma and diabetic retinopathy (DR) are the leading causes of irreversible retinal damage leading to blindness. Early detection of these diseases through regular screening is especially important to prevent progression. Retinal fundus imaging serves as the principal method for diagnosing glaucoma and DR. Consequently, automated detection of eye diseases represents a significant application of retinal image analysis. Compared with classical diagnostic techniques, image classification by convolutional neural networks (CNN) exhibits potential for effective eye disease detection. Methods This paper proposes the use of MATLAB

Metabolomic analysis of retinopathy stages and amputation in type 2 diabetes

BackgroundDiabetic retinopathy (DR) and limb amputation are frequent complications of diabetes that cannot always be explained by blood glucose control. Metabolomics is a science that is currently being explored in the search for biomarkers or profiles that identify clinical conditions of interest. ObjectiveThis study aimed to analyze, using a metabolomic approach, peripheral blood samples from type 2 diabetes mellitus (DM2) individuals, compared with those with diabetic retinopathy and limb amputation. MethodsThe sample consisted of 128 participants, divided into groups: control, DM2 without DR (DM2), non-proliferative DR (DRNP), proliferative DR (DRP), and DM2 amputated (AMP). Metabolites from blood plasma were classified by spectra using nuclear magnetic resonance (NMR), and the metabolic routes of each group using metaboanalyst. ResultsWe identified that the metabolism of phenylalanine, tyrosine, and tryptophan was discriminant for the DRP group. Histidine biosynthesis, on the other hand, was statistically associated with the AMP group. The results of this work consolidate metabolites such as glutamine and citrulline as discriminating for DRP, and the branched-chain amino acids as important for DR. ConclusionsThe results demonstrate the relationship between the metabolism of ketone bodies, with acetoacetate metabolite being discriminating for the DRP group and histidine being a significant metabolite in the AMP group, when compared to the DM2 group.

Haplotype-based association study of TCF7L2 gene variants with the development of diabetic retinopathy in an Iranian population

ABSTRACT Background Diabetic retinopathy (DR) is recognized as one of the most prevalent complications of diabetes and a major cause of morbidity. Transcription factor 7-like 2 (TCF7L2), a pivotal component in the Wnt-signaling pathway, plays a significant role in β-cell development, blood-glucose homeostasis, cell survival, cell migration, and cell proliferation. Thus, this study aimed to assess the association between TCF7L2 variants (rs7903146, rs11196205, and rs12255372) with DR in a population-based association study. Materials and Methods DNA was extracted from whole blood of all subjects by salting-out procedure. Total 524 T2DM patients including 234 T2DM individuals without DR and 290 T2DM individuals with DR were genotyped by TaqMan assay technology. Clinical characteristics of subjects were conducted to evaluate the plausible association between TCF7L2 variants and DR with univariate linear regression analysis. Results Demographic analysis between case and control groups revealed significant differences in FBS, HbA1c, lipidemia, heart disease, and family history of T2DM (p < 0.05). No significant difference was observed in either genotypes distribution or allele frequency (p > 0.05) between T2DM individuals with and without DR in any models of inheritance. Genotype-phenotype association showed no significant association. Result of analysis indicated that HbAlc with adjusted OR of 1.8 (p < 0.0001) and first-degree relatives of family history with adjusted OR of 3.04 (p < 0.0001) were significantly associated with DR. Finally, haplotype analysis showed no noticeable association. Conclusion In conclusion, there was no significant genetic association between rs7903146, rs11196205, and rs12255372 with DR among T2DM Iranians; however, these variants may play unknown roles in other populations.

Statins as a risk factor for diabetic retinopathy: a Mendelian randomization and cross-sectional observational study

BackgroundDiabetic retinopathy (DR) is the foremost cause of vision loss among the global working-age population, and statins are among the most frequently prescribed drugs for lipid management in patients with DR. The exact relationship between statins and DR has not been determined. This study sought to validate the causal association between statins usage and diabetic retinopathy.MethodsThe summary-data-based Mendelian randomization (SMR) method and inverse-variance-weighted Mendelian randomization (IVW-MR) were used to identify the causal relationship between statins and DR via the use of expression quantitative trait loci (eQTL) data for 3-hydroxy-3-methylglutaryl-coenzyme A reductase (HMGCR) (31,684 blood samples), low density lipoprotein cholesterol-related GWAS data (sample size: 440,546), and DR-related GWAS data (14,584 cases and 176,010 controls). Additionally, a cross-sectional observational study based on the data from the National Health and Nutrition Examination Survey (NHANES) was conducted to supplement the association between DR and statins (sample size: 106,911). The odds ratios (ORs) with corresponding 95% confidence intervals (CIs) was employed to evaluate the results.ResultsBased on the results of the MR analysis, HMGCR inhibitors were causally connected with a noticeably greater incidence of DR (IVW: OR = 0.54, 95% CI [0.42, 0.69], p = 0.000002; SMR: OR = 0.66, 95% CI [0.52, 0.84], p = 0.00073). Subgroup analysis revealed that the results were not affected by the severity of DR. The sensitivity analysis revealed the stability and reliability of the MR analysis results. The results from the cross-sectional study based on NHANES also support the association between not taking statins and a decreased risk of DR (OR = 0.54, 95% CI [0.37, 0.79], p = 0.001).ConclusionsThis study revealed that a significant increase in DR risk was causally related to statins use, providing novel insights into the role of statins in DR. However, further investigations are needed to verify these findings.

N-glycosylation of disease-specific haptoglobin for the early screening of diabetic retinopathy.

Diabetic retinopathy (DR), as one of the microvascular complications of diabetes, is a leading cause of acquired vision loss. Most DR cases are detected in the advanced stage through fundoscopy, making molecular biomarkers urgently needed for early diagnosis of DR. Serum disease-specific haptoglobin-β (Hp-β) chains of 100 patients with type 2 diabetes mellitus (T2DM) and 156 T2DM patients with non-proliferative diabetic retinopathy (NPDR) were separated using polyacrylamide gel electrophoresis. After in-gel digestion and enrichment, the intact N-glycopeptides were detected by mass spectrometry. Fucosylation of Hp-β was significantly increased and sialylation of Hp-β was significantly decreased in background DR (BDR, an early-stage DR) patients compared with non-diabetic retinopathy patients (p<0.05) and yielded area under curves (AUCs) of 0.801 and 0.829 in training and validation groups, respectively, which had an advantage over glycated hemoglobin A1c (AUC ≤ 0.691). Moreover, a significant increase in sialylated Hp-β was found in severe NPDR patients compared with BDR patients and yielded an AUC of 0.828 to distinguish severe NPDR from BDR. Changes in Hp-β glycosylation are closely related to DR, and may be used for early diagnosis and screening of DR.

An analysis of the relationship between ABCC8 and KCNJ11 gene polymorphisms and diabetic retinopathy in Turkish population

ABSTRACT Background Diabetic retinopathy (DR) occurs due to high blood glucose damage to the retina and leads to blindness if left untreated. KATP and related genes (KCNJ11 and ABCC8) play an important role in insulin secretion by glucose-stimulated pancreatic beta cells and the regulation of insulin secretion. KCNJ11 E23K (rs5219), ABCC8–3 C/T (rs1799854), Thr759Thr (rs1801261) and Arg1273Arg (rs1799859) are among the possible related single nucleotide polymorphisms (SNPs). The aim of this study is to find out how DR and these SNPs are associated with one another in the Turkish population. Materials and methods This study included 176 patients with type 2 diabetes mellitus without retinopathy (T2DM-rp), 177 DR patients, and 204 controls. Genomic DNA was extracted from whole blood, and genotypes were determined by the PCR-RFLP method. Results In the present study, a significant difference was not found between all the groups in terms of Arg1273Arg polymorphism located in the ABCC8 gene. The T allele and the TT genotype in the −3 C/T polymorphism in this gene may have a protective effect in the development of DR (p = 0.036 for the TT genotype; p = 0.034 for T allele) and PDR (p = 0.042 and 0.025 for the TT genotype). The AA genotype showed a significant increase in the DR group compared to T2DM-rp in the KCNJ11 E23K polymorphism (p = 0.046). Conclusions Consequently, the T allele and TT genotype in the −3 C/T polymorphism of the ABCC8 gene may have a protective marker on the development of DR and PDR, while the AA genotype in the E23K polymorphism of the KCNJ11 gene may be effective in the development of DR in the Turkish population.

Structured Counselling and Regular Telephonic follow up to improve Referral flow and compliance in Nepal for Diabetic Retinopathy(SCREEN-D Study): a randomised controlled trial

BackgroundDiabetic Retinopathy (DR) is an emerging public health issue, leading to severe visual impairment or blindness. Early identification and prompt treatment play a key role in achieving good visual outcomes. The objective of the study was to estimate the effectiveness of SCREEN package on improving referral compliance from peripheral centres to a tertiary eye centre in Nepal.MethodsIn this facility-based cluster-randomized trial, ten out of 19 referring centres of the tertiary eye care centre in Lumbini zone, Nepal were randomized into intervention and control groups. A SCREEN packagewereprovided as intervention for DR patients who require advanced treatment in the tertiary centres and was compared with the current practice of the control arm, where structured counselling and follow-up mechanism are absent. Compliance was estimated by a weekly follow-up between the referring centre and the referred hospital.ResultsWe recruited 302 participantsof whom 153 were in the intervention arm. The mean age of the participants was 57.8 years (Standard deviation [SD]±11.7 years). With implementation of SCREEN package71.2% (n=109) in the intervention group and 42.9% (n=64) in the control group were compliant till three months of follow-up (Difference 28.3%, 95% CI: 17.6- 39.0, p<0.05). Compliance was 43% (n=66) with counselling alone, and 66% (n=103) with first telephonic follow-up in the intervention arm. The mean duration to reach the referral centre was 14.7 days (SD± 9.4 days) and 18.2 days (SD± 9.1 days) in the intervention and the control arm, respectively (Difference 3.5 days, 95% CI: 0.7 to 6.4 days).ConclusionsCounselling& follow-up to patients is the key factor to improve the utilization of the health services by patients with DR. Health systems must be strengthened by optimizing the existing referral structure in Nepal.Trial registrationClinicalTrials.gov Protocol Registration and Results System, ClinicalTrials.gov Identifier: NCT04834648, 08/04/2021.

Retinal capillary perfusion heterogeneity in diabetic retinopathy detected by optical coherence tomography angiography

BackgroundDiabetic retinopathy (DR) is a leading cause of blindness and involves retinal capillary damage, microaneurysms, and altered blood flow regulation. Optical coherence tomography angiography (OCTA) is a non-invasive way of visualizing retinal vasculature but has not been used extensively to study blood flow heterogeneity. The purpose of this study is to detect and quantify blood flow heterogeneity utilizing en-face swept source OCTA in patients with DR.MethodsThis is a prospective clinical study which examined patients with either type 1 or 2 diabetes mellitus. Each included eye was graded clinically as no DR, mild DR, or moderate-severe DR. Ten consecutive en face 6 × 6 mm foveal SS-OCTA images were obtained from each eye using a PLEX Elite 9000 (Zeiss Meditec, Dublin, CA). Built-in fixation-tracking, follow-up functions were utilized to reduce motion artifacts and ensure same location imaging in sequential frames. Images of the superficial and deep vascular complexes (SVC and DVC) were arranged in temporal stacks of 10 and registered to a reference frame for segmentation using a deep neural network. The vessel segmentation was then masked onto each stack to calculate the pixel intensity coefficient of variance (PICoV) and map the spatiotemporal perfusion heterogeneity of each stack.ResultsTwenty-nine eyes were included: 7 controls, 7 diabetics with no DR, 8 mild DR, and 7 moderate-severe DR. The PICoV correlated significantly and positively with DR severity. In patients with DR, the perfusion heterogeneity was higher in the temporal half of the macula, particularly in areas of capillary dropout. PICoV also correlates as expected with the established OCTA metrics of perfusion density and vessel density.ConclusionPICoV is a novel way to analyze OCTA imaging and quantify perfusion heterogeneity. Retinal capillary perfusion heterogeneity in both the SVC and DVC increased with DR severity. This may be related to the loss of retinal capillary perfusion autoregulation in diabetic retinopathy.

Homocysteine and mitochondrial quality control in diabetic retinopathy

BackgroundDiabetic retinopathy is a progressive disease, and one of the key metabolic abnormalities in the pathogenesis of diabetic retinopathy, mitochondrial damage, is also influenced by the duration of hyperglycemia. Mitochondrial quality control involves a coordination of mitochondrial dynamics, biogenesis and removal of the damaged mitochondria. In diabetes, these processes are impaired, and the damaged mitochondria continue to produce free radicals. Diabetic patients also have high homocysteine and reduced levels of hydrogen sulfide, and hyperhomocysteinemia is shown to exacerbate diabetes-induced mitochondrial damage and worsen their dynamics. This study aims to investigate the temporal relationship between hyperhomocysteinemia and retinal mitochondrial quality control in diabetic retinopathy.MethodsHuman retinal endothelial cells incubated in 20 mM d-glucose for 24 to 96 h, in the absence or presence of 100 µM homocysteine, with/without a hydrogen sulfide donor GYY4137, were analyzed for mitochondrial ROS (MitoSox fluorescence), DNA damage (transcripts of mtDNA-encoded ND6 and CytB), copy numbers, oxygen consumption rate (Seahorse XF analyzer) and mitophagy (mitophagosomes immunofluorescence labeling and flow cytometry). Results were confirmed in the retina from mice genetically manipulated for hyperhomocysteinemia (cystathionine β-synthase deficient mice, Cbs+/−), streptozotocin-induced diabetic for 8 to 24 weeks. At 24 weeks of diabetes, vascular health was evaluated by counting acellular capillaries in the trypsin digested retinal vasculature and by fluorescein angiography.ResultsHomocysteine, in high glucose medium, exacerbated mitochondrial ROS production, mtDNA damage and impaired mitochondrial respiration within 24 h, and slowed down/worsened mitochondrial biogenesis and mitophagy, as compared to 48 to 96 h in high glucose alone. GYY4137 supplementation ameliorated homocysteine + high glucose-induced mitochondrial damage and impairment in biogenesis and mitophagy. Similar results were obtained from Cbs+/− mice-mitochondrial ROS, mtDNA damage and decline in biogenesis and mitophagy were observed within eight weeks of diabetes vs. 16 to 24 weeks of diabetes in Cbs+/+ mice, and at 24 weeks of diabetes, Cbs+/− mice had significantly higher acellular capillaries and vascular leakage.ConclusionsHyperhomocysteinemia, in a hyperglycemic environment, overwhelms the mitochondria, accelerating and exacerbating their dysfunction, and also delays/worsens their removal, augmenting the development of diabetic retinopathy. Thus, our results strengthen the importance of maintaining homocysteine-hydrogen sulfide balance during the early stages of diabetes for a patient to prevent/retard vision loss.

Potential disease biomarkers for diabetic retinopathy identified through Mendelian randomization analysis.

Diabetic retinopathy (DR), a leading cause of vision loss, has limited options for effective prevention and treatment. This study aims to utilize genomics and proteomics data to identify potential drug targets for DR. We utilized plasma protein quantitative trait loci data from the Atherosclerosis Risk in Communities Study and the Icelandic Decoding Genetics Study for discovery and replication, respectively. Genetic associations with DR, including its subtypes, were derived from the FinnGen study. Mendelian Randomization (MR) analysis estimated associations between protein levels and DR risk, complemented by colocalization analysis to examine shared causal variants. Our MR analysis identified significant associations of specific plasma proteins with DR and proliferative DR (PDR). Elevated genetically predicted levels of WARS (OR = 1.16; 95% CI = 0.095-0.208, FDR = 1.31×10-4) and SIRPG (OR = 1.15; 95% CI = 0.071-0.201, FDR = 1.46×10-2) were associated with higher DR risk, while increased levels of ALDOC (OR = 1.56; 95% CI = 0.246-0.637, FDR = 5.48×10-3) and SIRPG (OR = 1.15; 95% CI = 0.068-0.208, FDR = 4.73×10-2) were associated with higher PDR risk. These findings were corroborated by strong colocalization evidence. Our study highlights WARS, SIRPG, and ALDOC as significant proteins associated with DR and PDR, providing a basis for further exploration in drug development. Additional studies are needed to validate these proteins as disease biomarkers across diverse populations.

Retinal neurovascular alteration in type 2 diabetes with renal impairment in association with systemic arterial stiffness

BackgroundDiabetic retinopathy (DR) patients should be alert for subclinical macroangiopathy. We aimed to investigate the association between retinal neurovascular alteration and systemic arterial stiffness in type 2 diabetes mellitus (type 2 DM) patients with varying degrees of renal impairment.MethodsThe study included 170 patients with confirmed diagnosis of type 2 DM aged ≥18 years old. Renal function was assessed by estimated glomerular filtration rate (eGFR). Arterial stiffness was measured by brachial-ankle pulse wave velocity (baPWV) and ankle brachial index (ABI). Retinal neurovascular parameters were derived from Optical Coherence Tomography (OCT)/OCT-Angiography, represented by vessel density (VD Central, Inner, Outer, Full), foveal avascular zone (FAZ area and FAZ perimeter) of the superficial capillary plexus, the average of macular ganglion cell-inner plexiform layer thickness (ave mGC-IPLt) and the average of retinal nerve fiber layer thickness (aveRNFLt). The association between variables among the groups (according to renal function, diabetic retinopathy (DR) severity, and arterial stiffness categories) were analyzed by regression analysis with multiple hypothesis testing commands.ResultsOut of the 265 eyes, the mean DM duration and HbA1c were 6.21 ± 6.37 years and 8.44 ± 2.06% respectively. While the mean of eGFR, baPWV and ABI were 66.78 ± 32.80 ml/min/1.73m2, 15.49 ± 3.07 m/s, and 1.05 ± 0.12, respectively. Patients with more severe renal impairment demonstrated longer DM duration (p < 0.001), higher baPWV (p < 0.0001), and retinal vascular alteration. Proliverative DR group showed the lowest eGFR (p < 0.0001), highest baPWV (p < 0.0001), and retinal neurovascular changes. Significantly lower eGFR and retinal vascular alteration were found in the baPWV > 14 group. Some neurovascular parameters were significantly negatively correlated with baPWV; moreover, retinal neurovascular changes were also noted in the abnormal ABI group.ConclusionsThe strong association between changes in the retinal neurovascular system, DR severity, renal impairment, and arterial stiffness in type 2 DM was confirmed. Patients with more severe renal impairment had higher levels of arterial stiffness, more severe DR and retinal neurovascular alteration. Retinal neurovascular changes seen in OCT/OCTA might mimic renal microvascular alteration and systemic arterial stiffness. Therefore, assessment of baPWV and OCT/OCTA should be integrated in DR screening to enhance cardiovascular risk stratification and prognosis as well as to provide clinically useful early identification of subclinical micro- and macrovascular alterations.