Circulating markers of inflammation and endothelial function, and their relationship to diabetic retinopathy

Toxoplasma gondii, endothelial cells and schizophrenia: is it just a barrier matter?

Toxoplasma gondii is an obligatory intracellular parasite responsible for causing toxoplasmosis. It is estimated that approximately one-third of the world's population has positive serology for toxoplasmosis. Acute T. gondii infection often results in subtle symptoms because of its nonspecific nature. Owing to immune pressure, parasites tend to encyst and persist in different tissues and organs, such as the brain, chronicling the infection. While most chronically infected individuals do not develop significant symptoms, the parasite can affect the central nervous system (CNS), leading to symptoms that range from dizziness to behavioral changes. To reach the CNS, parasites must overcome the blood-brain barrier, which is composed primarily of endothelial cells. While these cells are typically efficient at separating blood elements from the CNS, in T. gondii infection, they not only permit parasitic colonization of the CNS but also contribute to an inflammatory profile that may exacerbate previously established conditions at both the local CNS and systemic levels. An increasing body of research has demonstrated a potential link between the CNS, infection by T. gondii and the cellular or humoral response to infection, with the worsening of psychiatric conditions, such as schizophrenia. Therefore, continually advancing research aimed at understanding and mitigating the relationship between parasitic infection and schizophrenia is imperative.

The causal relationship between immune cells and diabetic retinopathy: a Mendelian randomization study

Purpose

This article explored the causal relationship between immune cells and diabetic retinopathy (DR) using single nucleotide polymorphisms (SNPs) as an instrumental variable and Mendelian randomization (MR).

Methods

Statistical data were collected from a publicly available genome-wide association study (GWAS), and SNPs that were significantly associated with immune cells were used as instrumental variables (IVs). Inverse variance weighted (IVW) and MR-Egger regression were used for MR analysis. A sensitivity analysis was used to test the heterogeneity, horizontal pleiotropy, and stability of the results.

Results

We investigated the causal relationship between 731 immune cells and DR risk. All the GWAS data were obtained from European populations and from men and women. The IVW analysis revealed that HLA DR on CD14+ CD16- monocytes, HLA DR on CD14+ monocytes, HLA DR on CD33-HLA DR+, HLA DR on CD33+ HLA DR+ CD14- on CD33+ HLA DR+ CD14dim, and HLA DR on myeloid dendritic cells may increase the risk of DR (P<0.05). HLA DR to CD14-CD16- cells, the monocytic myeloid-derived suppressor cell absolute count, the SSC-A count of CD4+ T cells, and terminally differentiated CD4+ T cells may be protective factors against DR (P<0.05). The sensitivity analysis indicated no heterogeneity or pleiotropy among the selected SNPs. Furthermore, gene annotation of the SNPs revealed significant associations with 10 genes related to the risk of developing PDR and potential connections with 12 other genes related to PDR.

Conclusion

Monocytes and T cells may serve as new biomarkers or therapeutic targets, leading to the development of new treatment options for managing DR.

Current Trends in Diagnosis and Treatment Approach of Diabetic Retinopathy during Pregnancy: A Narrative Review

Diabetes mellitus during pregnancy and gestational diabetes are major concerns worldwide. These conditions may lead to the development of severe diabetic retinopathy during pregnancy or worsen pre-existing cases. Gestational diabetes also increases the risk of diabetes for both the mother and the fetus in the future. Understanding the prevalence, evaluating risk factors contributing to pathogenesis, and identifying treatment challenges related to diabetic retinopathy in expectant mothers are all of utmost importance. Pregnancy-related physiological changes, including those in metabolism, blood flow, immunity, and hormones, can contribute to the development or worsening of diabetic retinopathy. If left untreated, this condition may eventually result in irreversible vision loss. Treatment options such as laser therapy, intravitreal anti-vascular endothelial growth factor drugs, and intravitreal steroids pose challenges in managing these patients without endangering the developing baby and mother. This narrative review describes the management of diabetic retinopathy during pregnancy, highlights its risk factors, pathophysiology, and diagnostic methods, and offers recommendations based on findings from previous literature.

Potential disease biomarkers for diabetic retinopathy identified through Mendelian randomization analysis

Background

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.

Methods

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.

Results

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.

Conclusions

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.

Association between the Prognostic Nutritional Index and Chronic Microvascular Complications in Patients with Type 2 Diabetes Mellitus

The prognostic nutritional index (PNI) is associated with inflammatory conditions. Since type 2 diabetes mellitus (T2DM) and its microvascular complications produce a significant inflammatory burden, we aimed to compare the PNI levels of the subjects with T2DM to those of healthy individuals. Furthermore, we aimed to compare the PNI levels of the diabetic subjects, with and without microvascular complications. The study cohort consisted of T2DM patients and healthy volunteers. The general characteristics, laboratory data, and PNI of the T2DM and control groups were compared. We further compared the PNI levels of the diabetic patients, with and without diabetic microvascular complications. The PNI levels of the T2DM patients and the control group were 51.6 (30.1-73.8)% and 64.8 (49.4-76)%, respectively (p < 0.001). Subgroup analyses revealed that the PNI was lower in the diabetic subjects with diabetic microvascular complications than in the diabetic patients without microvascular complications (p < 0.001), in patients with diabetic nephropathy compared to those without nephropathy (p < 0.001), in patients with diabetic retinopathy compared to those without retinopathy (p < 0.001), and in patients with diabetic neuropathy compared to those without neuropathy (p < 0.001). In conclusion, we assert that assessing the PNI may yield additional diagnostic value in regards to the timely determination of diabetic microvascular complications.

ADAMTS5 promotes neovascularization via autophagic degradation of PEDF in proliferative diabetic retinopathy

Proliferative diabetic retinopathy (PDR) adversely affects visual function. Extracellular matrix proteins (ECM) contribute significantly to the development of PDR. A Disintegrin and Metalloproteinase with Thrombospondin motifs 5 (ADAMTS5) is a member of ECM proteins. ADAMTS5 participates in angiogenesis and inflammation in diverse diseases. However, the role of ADAMTS5 in PDR remains elusive. Multiplex beam array technology was used to analyze vitreous humor of PDR patients and normal people. ELISA and Western blot were used to detect the expression of ADAMTS5, PEDF and autophagy related factors. Immunofluorescence assay was used to mark the expression and localization of ADAMTS5 and PEDF. The neovascularization was detected by tube formation test. Our results revealed that ADAMTS5 expression was increased in the vitreous humor of PDR patients and oxygen-induced retinopathy (OIR) mice retinas. Inhibiting ADAMTS5 alleviated pathological angiogenesis and upregulated PEDF expression in the OIR mice. In addition, ADAMTS5 inhibited PEDF secretion in ARPE-19 cells in vitro studies, thereby inhibiting the migration of HMEC-1. Mechanically, ADAMTS5 promoted the autophagic degradation of PEDF. Collectively, inhibition of ADAMTS5 during OIR suppresses pathological angiogenesis. Our study provides a new approach for resolving pathological angiogenesis in PDR.

Circulatory Biomarkers and Diabetic Retinopathy in Racial and Ethnic Populations

Clinical staging systems for diagnosis and treatment of diabetic retinopathy (DR) must closely relate to endpoints that are both relevant for patients and feasible for physicians to implement. Current DR staging systems for clinical eye care and research provide detailed phenotypic characterization to predict patient outcomes in diabetes but have limitations. Biochemical biomarkers provide a rich pool of potential candidates for new DR staging systems that can be readily measured in accessible fluids. Circulating biomarkers that are specific to the retina and relate to angiogenesis and inflammation have been suggested as relevant for DR. Although there is a lack of multi-ethnic studies evaluating circulatory biomarkers in DR, variability in circulatory biomarkers have been reported in people from different ethnic and racial backgrounds. Therefore, there is a need for future studies to evaluate individual or combinations of biomarkers in diverse populations with DR from different ethnic and racial backgrounds.

Elevated aqueous endothelin-1 concentrations in advanced diabetic retinopathy

Purpose

Endothelin-1 (ET-1) is a potent vasoconstrictor which seems to be involved in the pathogenesis of diabetic retinopathy (DR). However, studies on intraocular ET-1 in DR have been limited. Thus, we investigated aqueous ET-1 levels in patients with DR.

Methods

A total 85 subjects were included in this prospective study. Those were classified into three groups: advanced DR group included those with severe nonproliferative DR or proliferative DR, whereas early DR group included those with mild nonproliferative DR or moderative nonproliferative DR. Those who underwent cataract surgery and had no concomitant ocular disease were included in the control group. Aqueous humor levels of ET-1 were obtained before intravitreal bevacizumab injection (IVB) and after 1 month for the DR patients, and at the time of cataract surgery for the control group.

Results

Advanced DR group included 40 eyes (47.1%), whereas early DR group did 19 eyes (22.4%), and control group (26 eyes, 30.5%). Mean aqueous ET-1 level was 10.1±4.1 pg/mL (6.0–21.0 pg/mL) in advanced DR group, 1.9±0.7 pg/mL (0.6–2.8 pg/mL) in early DR group, and 2.1±1.0 pg/mL (0.7–3.9 pg/mL) in control group (P < 0.001). Advanced DR group was further subdivided into severe nonproliferative DR (15 eyes, 12.8%) and proliferative DR (25 eyes, 34.3%). Mean aqueous ET-1 level was 10.1±4.3 pg/mL (6.0–20.1 pg/mL) in patients with severe nonproliferative DR, and 10.0±4.0 pg/mL (6.0–21.0 pg/mL) in those with proliferative DR (P = 0.928) at baseline. Mean ET-1 level at 1 month after intravitreal injection was 2.5±1.0 pg/mL (0.3–4.8 pg/mL) in patients with severe proliferative DR and 2.9±1.7 pg/mL (1.0–7.0 pg/mL) in those with proliferative DR (P = 0.443). Mean aqueous ET-1 level was significantly reduced in both groups (P < 0.001, respectively).

Conclusion

The mean aqueous ET-1 level was significantly higher in the eyes with advanced DR than those with early DR and the control group. The mean aqueous ET-1 level was significantly reduced after intravitreal injections in the advanced DR group. Based on our results, future studies on the exact role of ET-1 in the pathogenesis of DR and future implication for intervention would be helpful for managing DR.

Association of WBC Counts, Leukocyte Ratios, and Serum Uric Acid with Clinical Outcome of Intravitreal Bevacizumab in Diabetic Macular Edema

Purpose

To investigate the role of serum uric acid and leukocyte counts and ratios as predictors of clinical outcomes of intravitreal bevacizumab in diabetic macular edema.

Method

In this prospective study, the patients were treated with three monthly intravitreal bevacizumab. The correlation of serum uric acid and immune cell indices with the changes of best corrected visual acuity and central macular thickness at the end of month 3 were evaluated through univariate and multivariate linear regression analysis.

Result

A total of 80 eyes from 80 diabetic patients were included in the study. The difference of uric acid level and immune indices between groups with different retinopathy severity was no statistically significant(P>0.05). Lower duration of diabetes (P=0.0451), monocyte count (P=0.021), and uric acid level (P<0.001) were correlated with larger improvement in visual acuity at 3-month visit. Higher logMAR of baseline visual acuity (P=0.007), lymphocyte count (P=0.008), lymphocyte-to-neutrophil ratio (LNR) (P<0.001) and lymphocyte-to-platelet ratio (LPR) (P<0.001) were correlated with larger improvement in visual acuity at 3-month visits. According to multivariate analysis, baseline logMAR (coefficient=0.125, P=0.009), duration of diabetes (coefficient=-0.216, P=0.047), LNR (coefficient=0.712, P<0.001), LPR (coefficient=0.238, P<0.001), and uric acid level (coefficient=-0.397, P<0.001) were the significant predictors of changes in visual acuity in our subset of patients.

Conclusion

Serum uric acid and leukocyte counts and ratios may predict the response of diabetic macular edema to intravitreal injection.

Association of the Monocyte-to-High-Density Lipoprotein Cholesterol Ratio With Diabetic Retinopathy

Background: Chronic inflammation in type 2 diabetes mellitus (T2DM) is an essential contributor to the development of diabetic retinopathy (DR). The monocyte–to–high-density lipoprotein cholesterol (HDL-C) ratio (MHR) is a novel and simple measure related to inflammatory and oxidative stress status. However, little is known regarding the role of the MHR in evaluating the development of DR.

Methods: A total of 771 patients with T2DM and 607 healthy controls were enrolled in this cross-sectional study. MHR determination and eye examination were performed. The association of MHR with the prevalence of DR in T2DM patients was analyzed.

Results: The MHR in patients with DR was significantly higher than that in both non-DR diabetic patients (P < 0.05) and healthy controls (P < 0.01). No significance was observed in the MHR of different DR severity grades. Moreover, the MHR was similar between patients with non-macular oedema and those with macular oedema. Logistic regression analysis demonstrated that MHR was independently associated with the prevalence of DR in diabetic patients [odds ratio (OR) = 1.438, 95% confidence interval (CI): 1.249–1.655, P < 0.01]. After additional stratification by HbA1c level and diabetic duration, the MHR was still independently associated with the prevalence of DR.

Conclusions: Our study suggests that the MHR can be used as a marker to indicate the prevalence of DR in patients with T2DM.

From Oxidative Stress to Inflammation in the Posterior Ocular Diseases: Diagnosis and Treatment

Most irreversible blindness observed with glaucoma and retina-related ocular diseases, including age-related macular degeneration and diabetic retinopathy, have their origin in the posterior segment of the eye, making their physiopathology both complex and interconnected. In addition to the age factor, these diseases share the same mechanism disorder based essentially on oxidative stress. In this context, the imbalance between the production of reactive oxygen species (ROS) mainly by mitochondria and their elimination by protective mechanisms leads to chronic inflammation. Oxidative stress and inflammation share a close pathophysiological process, appearing simultaneously and suggesting a relationship between both mechanisms. The biochemical end point of these two biological alarming systems is the release of different biomarkers that can be used in the diagnosis. Furthermore, oxidative stress, initiating in the vulnerable tissue of the posterior segment, is closely related to mitochondrial dysfunction, apoptosis, autophagy dysfunction, and inflammation, which are involved in each disease progression. In this review, we have analyzed (1) the oxidative stress and inflammatory processes in the back of the eye, (2) the importance of biomarkers, detected in systemic or ocular fluids, for the diagnosis of eye diseases based on recent studies, and (3) the treatment of posterior ocular diseases, based on long-term clinical studies.

MicroRNA-301a-3p promotes diabetic retinopathy via regulation of six-transmembrane epithelial antigen of prostate 4

OBJECTIVE AND DESIGN

Diabetic retinopathy (DR) is one of the most serious microvascular complications of diabetes mellitus (DM). MicroRNAs (miRNAs) have been discovered to play a crucial role in DR, but the mechanisms underlying the effects of miR-301a-3p on DR are poorly understood. This paper was designed to explore the possible role of miR-301a-3p in DR.

METHODS

The diabetic rat model was established by a single intraperitoneal injection of streptozotocin (STZ). The effects of miR-301a-3p on the biological functions of HRECs were determined through a series of experiments in vitro/vivo.

RESULTS

The results revealed that interference with miR-301a-3p could decrease the expressions of inflammatory factors and apoptosis in the retinal tissue of DR. Furthermore, it can alleviate the oxidative stress in DR serum, reduce VEGF expression, increase endothelial cell marker expression, and inhibit (High Glucose) HG-induced apoptosis of HRECs. Six-transmembrane epithelial antigen of prostate 4 (STEAP4) was the target of miR-301a-3p. All the effects of miR-301a-3p in DR model were reversed by STEAP4 inhibitor.

CONCLUSION

miR-301a-3p promotes diabetic retinopathy via regulation of STEAP4. The findings in this study may provide a vital reference for the drug research and development in DR treatment.

Noncoding RNAs involved in DNA methylation and histone methylation, and acetylation in diabetic vascular complications

Diabetes is a metabolic disorder and its incidence is still increasing. Diabetic vascular complications cause major diabetic mobility and include accelerated atherosclerosis, nephropathy, retinopathy, and neuropathy. Hyperglycemia contributes to the pathogenesis of diabetic vascular complications via numerous mechanisms including the induction of oxidative stress, inflammation, metabolic alterations, and abnormal proliferation of EC and angiogenesis. In the past decade, epigenetic modifications have attracted more attention as they participate in the progression of diabetic vascular complications despite controlled glucose levels and regulate gene expression without altering the genomic sequence. DNA methylation and histone methylation, and acetylation are vital epigenetic modifications and their underlying mechanisms in diabetic vascular complication are still urgently needed to be investigated. Non-coding RNAs (nc RNAs) such as micro RNAs (miRNAs), long non-coding RNA (lncRNAs), and circular RNAs (circ RNAs) were found to exert transcriptional regulation in diabetic vascular complication. Although nc RNAs are not considered as epigenetic components, they are involved in epigenetic modifications. In this review, we summarized the investigations of non-coding RNAs involved in DNA methylation and histone methylation and acetylation. Their cross-talks might offer novel insights into the pathology of diabetic vascular complications.

Pathogenic role of human C-reactive protein in diabetic retinopathy

PURPOSE

Elevated blood levels of C-reactive protein (CRP) are associated with both type 1 and type 2 diabetes and diabetic complications, such as diabetic retinopathy (DR). However, its pathogenic role in DR remains unknown. The present study aims to investigate the potential role of CRP in DR pathogenesis and explore its underlying mechanism.

MATERIALS AND METHODS

Human CRP transgenic (hCRP-Tg) rats were employed for streptozotocin (STZ)-induced diabetic and oxygen-induced retinopathy (OIR) models. The retina function was monitored by electroretinography (ERG) and retinal thickness was measured by optical coherence tomography (OCT). TUNEL and cell death ELISA were performed to measure the apoptosis. Oxidative stress was detected by the measurement of reactive oxygen species (ROS) in cells and 3-Nitrotyrosine staining in tissue sections.

RESULTS

In non-diabetic condition, hCRP-Tg with elevated hCRP levels in the retinas demonstrated declined ERG responses and decreased retinal thickness. In STZ-induced diabetic condition, overexpression of hCRP deteriorated retinal neurodegeneration as shown by ERG and apoptosis assays. hCRP also exacerbated retinal leukostasis and acellular capillary formation induced by diabetes. In the OIR model, overexpression of hCRP exacerbated retinal neovascularization (NV). In retinal cell lines, hCRP treatment induced cell death and over-production of ROS. Furthermore, hCRP-induced overexpression of pro-inflammatory, pro-oxidative, and pro-angiogenic factors was associated with up-regulation of CD32 and the NF-κB signaling in the retinas.

CONCLUSIONS

Elevated hCRP levels play a pathogenic role in DR. Targeting the hCRP-CD32-NF-κB pathway may represent a novel therapeutic strategy for DR.

Dual-Acting Antiangiogenic Gene Therapy Reduces Inflammation and Regresses Neovascularization in Diabetic Mouse Retina

Intravitreal injections of anti-vascular endothelial growth factor drugs have become the gold standard treatment for diabetic retinopathy (DR). However, several patients are classified as non-responders or poor responders to treatment. Therefore, it is essential to study alternative target molecules. We have previously shown that the progression of DR in the Ins2^Akita mouse reflects the imbalance between pro- and anti-angiogenic molecules found in the human retina. We report, for the first time, the therapeutic potential of a dual-acting antiangiogenic non-viral gene therapy. We have used an expressing vector encoding both the pigment epithelium-derived factor gene and a short hairpin RNA (shRNA) targeted to the placental growth factor to restore the balance between these factors in the retina. Twenty-one days after a single subretinal injection, we observed a marked decrease in the inflammatory response in the neural retina and in the retinal pigment epithelium, together with reduced vascular retinal permeability in the treated diabetic mouse. These results were accompanied by the restoration of the retinal capillary network and regression of neovascularization, with significant improvement of DR hallmarks. Concomitant with the favorable therapeutic effects, this approach did not affect retinal ganglion cells. Hence our results provide evidence toward the use of this approach in DR treatment.

Contribution of inflammasome complex in inflammatory-related eye disorders and its implications for anti-inflammasome therapy

Inflammasome complex is regarded as a major molecular regulator that exerts a significant function in caspase-1 activation and consequently, the development of cytokines like interleukin-1β (IL-1β) and interleukin-18 (IL-18). The secretion of these cytokines may induce inflammation. The role of inflammasomes in the pathologic process of eye-related illnesses like glaucoma, age-related macular degeneration (AMD), and diabetic retinopathy has been well studied over the past decade. However, the detailed pathogenic mechanism of inflammasomes in these retinal diseases is still unknown. Therefore, further investigation and understanding various aspects of inflammasome complexes as well as their pivotal roles in the immunopathology of human ocular illnesses are essential. The present review aims to describe the significant involvement of inflammasomes in the immunopathology of important inflammatory retinal illnesses, including glaucoma, age-related macular degeneration (AMD), and diabetic retinopathy focusing on anti-inflammasome therapy as a promising approach in the treatment of inflammation-related eye diseases.

Risk factors for retinopathy in hemodialysis patients with type 2 diabetes mellitus

There is limited knowledge on the prevalence and risk factors of diabetic retinopathy (DR) in dialysis patients. We have investigated the association between diabetes mellitus and lipid-related biomarkers and retinopathy in hemodialysis patients. We reviewed 1,255 hemodialysis patients with type 2 diabetes mellitus (T2DM) who participated in the German Diabetes and Dialysis Study (4D Study). Associations between categorical clinical, biochemical variables and diabetic retinopathy were examined by logistic regression. On average, patients were 66 ± 8 years of age, 54% were male and the HbA1c was 6.7% ± 1.3%. DR, found in 71% of the patients, was significantly and positively associated with fasting glucose, HbA1c, time on dialysis, age, systolic blood pressure, body mass index and the prevalence of other microvascular diseases (e.g. neuropathy). Unexpectedly, DR was associated with high HDL cholesterol and high apolipoproteins AI and AII. Patients with coronary artery disease were less likely to have DR. DR was not associated with gender, smoking, diastolic blood pressure, VLDL cholesterol, triglycerides, and LDL cholesterol. In summary, the prevalence of DR in patients with type 2 diabetes mellitus requiring hemodialysis is higher than in patients suffering from T2DM, who do not receive hemodialysis. DR was positively related to systolic blood pressure (BP), glucometabolic control, and, paradoxically, HDL cholesterol. This data suggests that glucose and blood pressure control may delay the development of DR in patients with diabetes mellitus on dialysis.

Relationship between Proliferative Diabetic Retinopathy and Inflammatory Markers in Patients with Type 1 Diabetes in Brazil: A Nested Case Control Study

INTRODUCTION

This study examined the relationship between proliferative diabetic retinopathy (PDR) and serum levels of C-reactive protein, VEGF, TNF-α, and IL-6 inflammatory biomarkers, related to the pathophysiology of diabetic retinopathy.

METHODS

This cross-sectional, case control study comprised 240 patients with type 1 diabetes (80 cases with PDR and 160 controls without diabetic retinopathy) who were matched for gender and duration of diabetes.

RESULTS

C-reactive protein was the only inflammatory biomarker that was positively related to PDR (OR 1.96; 95% CI 1.01-3.78, p = 0.0045). We also noted an association between high glycated hemoglobin levels, the use of angiotensin-converting enzyme inhibitor, low glomerular filtration rate, and PDR.

CONCLUSION

Patients with higher levels of C-reactive protein are more likely to present with PDR. We did not find a link between serum levels of VEGF, TNF-α, or IL-6 and PDR. The function of inflammatory biomarkers in PDR must be addressed in further studies.

Systemic inflammation and dyslipidemia are associated with retinopathy in type 2 but not in type 1 diabetes

The aim of this study was to investigate risk factors and role of systemic inflammation, dyslipidemia and obesity in development of diabetic retinopathy (DR) in type 1 and type 2 diabetes and determine the differences in risk factors between these two types of diabetes. Eighty-four type 1 and 107 type 2 diabetic patients were included in this cross-sectional study. Diabetes duration, body mass index (BMI) and waist-to-hip ratio (WHR) were assessed. C-reactive protein (CRP), fibrinogen (FIB), glycated hemoglobin (HbA₁c), fasting and postprandial blood glucose (fBG, ppBG), HDL and LDL cholesterol and triglycerides (TG) were determined using routine methods. HbA₁c_median was obtained by statistical analysis of the CroDiabNet data and used as a marker of long-term glycemic control. Albumin excretion rate (AER) was measured in a 24-hour urine collection. Ophthalmologic retinal examination included indirect slit-lamp fundoscopy, color fundus photography according to EURODIAB (EUROpe and DIABetes) protocol and optical coherence tomography. DR was positively related to diabetes duration (p < .001), HbA₁c_median (p < .001) and AER (p = .008) in type 1, and diabetes duration (p < .001), HbA₁c_median (p = .018), AER (p < .001), CRP (p = .048) and TG (p = .041) in type 2 diabetes. Regression analysis showed that diabetes duration (OR 1.20, p = .005) and HbA₁c_median (OR 6.92, p = .007) were the main predictors of DR in type 1, and diabetes duration (OR 1.17, p < .001), fBG (OR 1.45, p = .024) and TG (OR 2.08, p = .025) in type 2 diabetes. In conclusion, systemic inflammation and dyslipidemia are associated with DR in type 2 but not in type 1 diabetes.

Effects of Coconut Water on Retina in Diabetic Rats

Coconut water (CW) is a natural aseptic nutritious beverage, containing several biologically active compounds. This study aimed to determine the antiretinopathy effects of CW on diabetic Sprague Dawley (SD) rats using streptozotocin (STZ) and explore its potential mechanism. After allowing the rats to acclimatize for 7 days, 48 healthy adult male SD rats were selected and randomly divided into 4 groups, involving control (Ctrl), diabetic rats (DM), diabetic rats treated with CW (DM-CW), and diabetic rats treated with glibenclamide (DM-Gli). The diabetic models were established by an intraperitoneal injection of STZ (60 mg/kg). The Ctrl group was injected with an equal volume of sodium citrate solution. The experiment was totally conducted during 20 weeks, and then, all rats were sacrificed. The serum levels of superoxide dismutase (SOD), malondialdehyde (MDA), and glutathione peroxidase (GSH-Px) were measured; additionally, the activities of interleukin-6 (IL-6) and intercellular adhesion molecule-1 (ICAM-1) in the retina were investigated using biochemical assays. Hematoxylin and eosin (H&E) staining was performed to observe pathological changes of retinal tissues. In presence of treatment with CW, serum level of MDA was decreased, while serum levels of SOD and GSH-Px were increased; besides, the activities of IL-6 and ICAM-1 in the retina were reduced compared with the DM group. The antiretinopathy feature of CW was confirmed by the increased number of neurons in the ganglion cell layer (GCL), total retina thickness (TRT), and thickness of the retinal nuclear layer (RNL) in diabetic rats. CW can be protective against diabetic retinopathy (DR), and its effects are comparable to Gli. The possible underlying mechanism may be partly explained by decreasing oxidative stress and anti-inflammatory activities in the retina. However, further research should be conducted to reveal the exact mechanism.

Endothelium as a Therapeutic Target in Diabetes Mellitus: From Basic Mechanisms to Clinical Practice

Endothelium plays an essential role in human homeostasis by regulating arterial blood pressure, distributing nutrients and hormones as well as providing a smooth surface that modulates coagulation, fibrinolysis and inflammation. Endothelial dysfunction is present in Diabetes Mellitus (DM) and contributes to the development and progression of macrovascular disease, while it is also associated with most of the microvascular complications such as diabetic retinopathy, nephropathy and neuropathy. Hyperglycemia, insulin resistance, hyperinsulinemia and dyslipidemia are the main factors involved in the pathogenesis of endothelial dysfunction. Regarding antidiabetic medication, metformin, gliclazide, pioglitazone, exenatide and dapagliflozin exert a beneficial effect on Endothelial Function (EF); glimepiride and glibenclamide, dipeptidyl peptidase-4 inhibitors and liraglutide have a neutral effect, while studies examining the effect of insulin analogues, empagliflozin and canagliflozin on EF are limited. In terms of lipid-lowering medication, statins improve EF in subjects with DM, while data from short-term trials suggest that fenofibrate improves EF; ezetimibe also improves EF but further studies are required in people with DM. The effect of acetylsalicylic acid on EF is dose-dependent and lower doses improve EF while higher ones do not. Clopidogrel improves EF, but more studies in subjects with DM are required. Furthermore, angiotensin- converting-enzyme inhibitors /angiotensin II receptor blockers improve EF. Phosphodiesterase type 5 inhibitors improve EF locally in the corpus cavernosum. Finally, cilostazol exerts favorable effect on EF, nevertheless, more data in people with DM are required.

Proteomic Biomarkers of Retinal Inflammation in Diabetic Retinopathy

Diabetic retinopathy (DR), a sight-threatening neurovasculopathy, is the leading cause of irreversible blindness in the developed world. DR arises as the result of prolonged hyperglycemia and is characterized by leaky retinal vasculature, retinal ischemia, retinal inflammation, angiogenesis, and neovascularization. The number of DR patients is growing with an increase in the elderly population, and therapeutic approaches are limited, therefore, new therapies to prevent retinal injury and enhance repair are a critical unmet need. Besides vascular endothelial growth factor (VEGF)-induced vascular proliferation, several other mechanisms are important in the pathogenesis of diabetic retinopathy, including vascular inflammation. Thus, combining anti-VEGF therapy with other new therapies targeting these pathophysiological pathways of DR may further optimize treatment outcomes. Technological advancements have allowed for high-throughput proteomic studies examining biofluids such as aqueous humor, vitreous humor, tear, and serum. Many DR biomarkers have been identified, especially proteins involved in retinal inflammatory processes. This review attempts to summarize the proteomic biomarkers of DR-associated retinal inflammation identified over the last several years.

Imaging and Biomarkers in Diabetic Macular Edema and Diabetic Retinopathy

PURPOSE OF REVIEW

Diabetic retinopathy (DR) is the leading cause of acquired vision loss in adults across the globe. Early identification and treatment of patients with DR is paramount for vision preservation. The aim of this review paper is to outline current and new imaging techniques and biomarkers that are valuable for clinical diagnosis and management of DR.

RECENT FINDINGS

Ultrawide field imaging and automated deep learning algorithms are recent advancements on traditional fundus photography and fluorescein angiography. Optical coherence tomography (OCT) and OCT angiography are techniques that image retinal anatomy and vasculature and OCT is routinely used to monitor response to treatment. Many circulating, vitreous, and genetic biomarkers have been studied to facilitate disease detection and development of new treatments. Recent advancements in retinal imaging and identification of promising new biomarkers for DR have the potential to increase detection, risk stratification, and treatment for patients with DR.

Role of ω3 polyunsaturated fatty acids in diabetic retinopathy: a morphological and metabolically cross talk among blood retina barriers damage, autoimmunity and chronic inflammation

Vision disorders are one of the most serious complications of diabetes mellitus (DM) affecting the quality of life of patients and eventually cause blindness. The ocular lesions in diabetes mellitus are located mainly in the blood vessels and retina layers. Different retina lesions could be grouped under the umbrella term of diabetic retinopathies (DMRP).

We propose that one of the main causes in the etiopathogenesis of the DMRP consists of a progressive loss of the selective permeability of blood retinal barriers (BRB). The loss of selective permeability of blood retinal barriers will cause a progressive autoimmune process. Prolonged autoimmune injures in the retinal territory will triggers and maintains a low-grade chronic inflammation process, microvascular alterations, glial proliferation and subsequent fibrosis and worse, progressive apoptosis of the photoreceptor neurons.

Patients with long-standing DM disturbances in retinal BRBs suffer of alterations in the enzymatic pathways of polyunsaturated fatty acids (PUFAs), increase release of free radicals and pro-inflammatory molecules and subsequently incremented levels of vascular endothelial growth factor. These facts can produce retinal edema and photoreceptor apoptosis.

Experimental, clinical and epidemiological evidences showing that adequate metabolic and alimentary controls and constant practices of healthy life may avoid, retard or make less severe the appearance of DMRP. Considering the high demand for PUFAs ω3 by photoreceptor complexes of the retina, it seems advisable to take fish oil supplements (2 g per day). The cellular, subcellular and molecular basis of the propositions exposed above is developed in this article.

Synthesizer drawings the most relevant findings of the ultrastructural pathology, as well as the main metabolic pathways of the PUFAs involved in balance and disbalanced conditions are provided.

Long Non-Coding RNA of Myocardial Infarction Associated Transcript (LncRNA-MIAT) Promotes Diabetic Retinopathy by Upregulating Transforming Growth Factor-β1 (TGF-β1) Signaling

Background

Long non-coding RNA of myocardial infarction associated transcript (lncRNA-MIAT) has a reported role in microvascular dysfunction. This study aimed to investigate the role of lncRNA-MIAT and its effects on transforming growth factor-β1 (TGF-β1) signaling in patients with diabetic retinopathy and in ARPE-19 adult retinal pigment epithelial cells in vitro.

Material/Methods

Study participants provided plasma samples and included patients with non-proliferative diabetic retinopathy (n=52), patients with diabetes without diabetic retinopathy (n=63), and healthy controls (n=56). Plasma levels of lncRNA-MIAT and TGF-β1 were detected by quantitative reverse transcription polymerase chain reaction (qRT-PCR) and enzyme-linked immunosorbent assay (ELISA), respectively. Pearson correlation analysis was performed on the plasma data, and the diagnostic relevance of plasma levels of lncRNA-MIAT for diabetic retinopathy was evaluated by receiver operating characteristic (ROC) curve analysis. Cells of the human retinal pigment epithelial cell line, ARPE-19, were cultured in high glucose with construction and transfection of a MIAT expression plasmid vector. Viability of ARPE-19 cells was detected by the MTT assay and Western blot measured the expression levels of TGF-β1.

Results

Plasma levels of lncRNA-MIAT were significantly increased in patients with diabetic retinopathy compared with patients with diabetes without diabetic retinopathy and with healthy controls. ARPE-19 cells cultured in a high glucose environment showed reduced cell viability and upregulation of lncRNA-MIAT expression.

Conclusions

Increased plasma levels of lncRNA-MIAT were significantly associated with the presence of diabetic retinopathy, and increased expression of lncRNA-MIAT reduced the viability of ARPE-19 cells in vitro by upregulating TGF-β1 signaling.

Systemic inflammation and eye diseases. The Beijing Eye Study

Purpose

Systemic inflammation is potentially associated with ocular diseases such as late age-related macular degeneration (AMD). Using the serum concentration of high-sensitive C-reactive protein (hs-CRP) as surrogate of systemic inflammation, we examined potential associations between the serum hs-CRP concentration and the presence and degree of eye diseases.

Methods

The population-based Beijing Eye Study included 3468 Chinese individuals. The study participants underwent a standardized interview and a detailed ophthalmic examination. The serum concentration of hs-CRP was determined.

Results

Out of 3468 participants, 2452 (70.7%) individuals (mean age:63.4±9.4 year; range:50–91 years) had hs-CRP measurements (mean:1.96±4.07mg/L). In multivariate analysis, higher serum concentration of hs-CRP was significantly (regression coefficient r: 0.21) associated with a higher level of diabetic retinopathy (P = 0.007; standardized regression coefficient beta:0.06; non-standardized regression coefficient B:1.35; 95% confidence interval (CI):0.37,2.22) and polypoidal choroidal vasculopathy (P = 0.002;beta:0.06;B:6.22;95%CI:2.24,10.2) after adjusting for higher serum concentration of high-density lipoproteins (P<0.001;beta:-0.12;B:-1.31;95%CI:-1.77,-0.85), higher body mass index (P = 0.01;beta:0.06;B:0.06;95%CI:0.01, 0.11), lower level of education (P = 0.04;beta:-0.06;B:-0.22;95%CI:-0.42,-0.02), lower cognitive function score (P = 0.01;beta:-0.07;B:-0.08;95%CI:-0.13,-0.02). If the presences of other ocular diseases were added to the model, the presence of glaucoma (P = 0.99), open-angle glaucoma (P = 0.80), angle-closure glaucoma (P = 0.67), pseudoexfoliation (P = 0.18), nuclear cataract (P = 0.30), cortical cataract (P = 0.15), subcapsular cataract (P = 0.59), retinal vein occlusions (P = 0.33), central serous choroidopathy (P = 0.44), early stage of age-related macular degeneration (AMD) (P = 0.46), intermediate stage of AMD (P = 0.20) and late stage of AMD (P = 0.91) including geographic atrophy (P = 0.60) or neovascular AMD (P = 0.68) were not significantly associated with the serum concentration of hs-CRP.

Conclusions

In Chinese aged 50+ years, higher serum concentration of hs-CRP was significantly associated with a higher level of diabetic retinopathy and higher frequency of polypoidal choroidal vasculopathy. Other major ocular disorders, namely glaucoma including open-angle glaucoma and angle-closure glaucoma, pseudoexfoliation, nuclear, cortical or subcapsular cataract, retinal vein occlusions, central serous choroidopathy, early, intermediate or late stage of AMD including geographic atrophy, were not significantly associated with hs-CRP serum concentrations. It suggests that these diseases, in contrast to diabetic retinopathy and polypoidal choroidal vasculopathy, were not associated with a major systemic inflammatory component.

Elevated RBP4 plasma levels were associated with diabetic retinopathy in type 2 diabetes

The retinol-binding protein 4 (RBP4) has been postulated to play a role in glucose homeostasis, insulin resistance, and diabetes mellitus in human and animal studies. The aim of the present study was to evaluate the role of RBP4 in Chinese patients with type 2 diabetes mellitus with and without diabetic retinopathy (DR). Plasma RBP4 concentrations were tested in 287 patients with type 2 diabetes. At baseline, demographic and clinical information including presence of DR and vision-threatening DR (VTDR) was collected. The relationship between RBP4 and DR (VTDR) was investigated using logistic regression. Patients with DR or VTDR had significantly higher plasma levels of RBP4 on admission (P<0.0001). Receiver operating characteristics (ROCs) to predict DR and VDTR demonstrated areas under the curve for RBP4 of 0.79 (95% confidence interval (CI): 0.73–0.85) and 0.90 (95% CI: 0.85–0.94), respectively, which were superior to other factors. For each 1 μg/ml increase in plasma level of RBP4, the unadjusted and adjusted risk of DR would be increased by 8% (with the odds ratio (OR) of 1.08 (95% CI: 1.05–1.13), P<0.001) and 5% (1.05 (1.02–1.11), P=0.001), respectively. It was 12% (with the OR of 1.12 (95% CI: 1.07–1.18), P<0.001) and 9% (1.09 (1.05–1.15), P<0.001) for VTDR. The present study shows that elevated plasma levels of RBP4 were associated with DR and VDTR in Chinese patients with type 2 diabetes, suggesting a possible role of RBP4 in the pathogenesis of DR complications. Lowering RBP4 could be a new strategy for treating type 2 diabetes with DR.

Association of Plasma Pentraxin-3 Levels with Retinopathy and Systemic Factors in Diabetic Patients

BACKGROUND

Diabetic retinopathy (DR) is mainly caused by metabolic factors, vascular inflammation, and endothelial dysfunction. We aimed to evaluate the relationship of DR with inflammatory and biochemical alterations in type 2 diabetics.

METHODS

A total of 89 diabetic patients with retinopathy [(DR (+) (n = 30)], without retinopathy [(DR (-) (n = 32)], and 27 control subjects were involved in the study. Demographic properties, biochemical values, ophtalmologic evaluation, C-reactive protein (CRP), and pentraxin-3 (PTX-3) levels were recorded.

RESULTS

There was significant difference between controls, DR (-) and DR (+) groups with regard to serum PTX-3 levels. Control group had the lowest and DR (+) group revealed the highest PTX-3 levels. Severity of retinopathy was not related with CRP or PTX-3 levels. Duration of diabetes was longer, systolic blood pressure (SBP) and urinary albumin-creatinine ratio (UACR) were significantly higher in DR (+) subjects than DR (-) subjects. Multivariate analysis revealed that PTX-3 level and SBP were the variables that had a significant effect on DR (P = 0.002, OR = 1.61, and P = 0.021, OR = 1.06, respectively).

CONCLUSIONS

Plasma PTX-3 levels may be a valuable predictor of DR-like factors such as duration of diabetes, hypertension, and UACR. Although inflammation has an important role in DR, we think that biomarkers reflecting inflammation is not sufficient to predict development and progression of DR; but follow up with PTX-3 levels along with ophthalmological evaluation may be useful. A single determination may not reflect the variations over time, so repeat measures may provide knowledge if PTX-3 is just a biomarker or has a causal role.

Serological inflammatory factors as biomarkers for anatomic response in diabetic macular edema treated with anti-VEGF

PURPOSE

To study the relationship between systemic pro-inflammatory factors and macular structural response to intravitreal bevacizumab for diabetic macular edema (DME).

METHODS

Prospective study including 30 cases with DME, treated with bevacizumab and a minimum follow-up of 6 months. All cases underwent baseline laboratory testing for cardiovascular risk (high sensitivity C-reactive protein (hsCRP), homocystein), dyslipidemia, renal dysfunction and glucose control. Serum levels of VEGF, soluble ICAM-1, MCP-1 and TNF-α were assessed by enzyme-linked immunosorbent assay kits. Significant associations between systemic factors and quantitative and qualitative spectral-domain optical coherence macular features were analyzed.

RESULTS

A mean of 4.82 ± 0.56 intravitreal injections was performed, resulting in significant improvement of central foveal thickness (CFT) (p < 0.001). A significant association with third month CFT decrease <10% was found for hsCRP (3.33 ± 2.01 vs 1.39 ± 1.15 mg/l, p = 0.007) and ICAM1 (975.54 ± 265.49 vs 727.07 ± 336.09 pg/ml, p = 0.012). ROC curve analysis indicated hsCRP and ICAM1 as significant biomarkers for 3rd month reduced anatomic response (area under the curve (AUC) = 0.807, p = 0.009 for hsCRP; AUC = 0.788, p = 0.014 for ICAM1). ROC curve analysis revealed hsCRP as a significant biomarker for 6th month CFT decrease <10% (AUC = 0.903, p < 0.001, cutoff value = 1.81 mg/l). A significant association with 6th month CFT decrease ≥25% was found for serum MCP1 (244.69 ± 49.34 pg/ml vs 319.24 ± 94.88 pg/ml, p = 0.017) and serum VEGF (90.84 ± 37.33 vs 58.28 ± 25.19 pg/ml, p = 0.027). The combined model of serum VEGF and LDL-cholesterol was found to be predictive of 6th month hard exudate severity (p = 0.001, r2 = 0.463).

CONCLUSIONS

Increased levels of hsCRP and ICAM1 were found to be significant biomarkers for early reduced anatomic response to anti-VEGF treatment. Cases with higher serum levels of such factors had increased CFT values, despite treatment, suggesting inner blood-retinal barrier breakdown that is not adequately responsive to anti-VEGF monotherapy.

Evaluation of Circulating Plasma VEGF-A, ET-1 and Magnesium Levels as the Predictive Markers for Proliferative Diabetic Retinopathy

Diabetic retinopathy (DR) is the most common cause for preventable blindness in India. The onset of micro and macrovascular complications in T2DM is multifactorial and difficult to predict. The status of micronutrients, several inflammatory cytokines, elevated triacylglycerols, oxidative stress etc., are being studied extensively. Hypomagnesemia plays a pivotal role in worsening of insulin resistance. Although, Vascular Endothelial Growth Factor-A (VEGF-A) and Endothelin-1 (ET-1) are known to be elevated in DR, yet few reports cite their role, especially in Indian population. In this study, we included thirty subjects with T2DM in each of the three groups namely, T2DM cases without retinopathy, Non Proliferative DR (NPDR) and Proliferative DR (PDR) retinopathy. The glycemic status, circulating plasma VEGF-A, ET-1 levels, serum magnesium and lipids were estimated and compared among the groups. An ROC was drawn to evaluate VEGF-A, ET-1 and serum magnesium levels as the predictive markers for PDR. On comparison VEGF-A, ET-1 and serum magnesium levels showed a significant difference among the three groups. PDR cases had higher circulating levels of VEGF-A, ET-1 and low serum magnesium levels when compared to others. ROC for VEGF-A and ET-1 showed an optimum cut-off of 1521 ng/ml (AUC 0.975) and 16 pg/ml (AUC 0.96) respectively. A negative ROC was drawn to check the lower cut-off limit for serum magnesium; we documented an optimum cut off of 1.7 mg/dl (AUC 0.837). ET-1, VEGF-A and serum Magnesium levels are significantly altered in PDR and can be used as the predictive markers of PDR.

The NLRP3 Inflammasome May Contribute to Pathologic Neovascularization in the Advanced Stages of Diabetic Retinopathy

Diabetic retinopathy (DR) is a retinal microvascular disease characterized by inflammatory and angiogenic pathways. In this study, we evaluated NLRP3 inflammasome in a double transgenic mouse model, Akimba (Ins2 Akita xVEGF+/-), which demonstrates hyperglycemia, vascular hyperpermeability and neovascularization seen in the proliferative DR. Retinal structural integrity, vascular leakage and function were examined by fundus photography, fluorescein angiography, optical coherence tomography, retinal flat mounts, laser speckle flowgraphy (LSFG), and electroretinography in Akimba and its parental strains, Akita (Ins2 Akita ) and Kimba (trVEGF029) mice. Inflammatory mechanisms involving NLRP3 inflammasome were investigated using real time-PCR, immunohistochemistry, ELISA and western blots. We observed an increased vascular leakage, reduced retinal thickness, and function in Akimba retina. Also, Akimba retina depicts decreased relative flow volume measured by LSFG. Most importantly, high levels of IL-1β along with increased NLRP3, ASC, and Caspase-1 at mRNA and protein levels were observed in Akimba retina. However, the in vivo functional role remains undefined. In conclusion, increased activation of macroglia (GFAP), microglia (Iba-1 and OX-42) and perivascular macrophages (F4/80 and CD14) together with pro-inflammatory (IL-1β and IL-6) and pro-angiogenic markers (PECAM-1, ICAM-1, VEGF, Flt-1, and Flk-1), suggested a critical role for NLRP3 inflammasome in the Akimba mouse model depicting advanced stages of DR pathogenesis.

Inflammation role in sensory neuropathy in Chinese patients with diabetes/prediabetes

OBJECTIVES

Prediabetes involves people with glucose-metabolism impairment, and is related to different diabetic complications, like peripheral neuropathy. We aimed to explore the relationship among inflammatory (tumor necrosis factor alpha [TNFα]) and antiinflammatory (interleukin 10 [IL10]) cytokines as well as neuropathy of very distal-sensory-nerves in Chinese patients with prediabetes/diabetes.

PATIENTS AND METHODS

In the present study, 55 patients having prediabetes, 55 patients having type 2 diabetes mellitus (DM), and 48 controls were included. TNFα, HbA1c, and IL10 plasma levels were measured. Electrodiagnosis was conducted on dorsal-sural/medial-plantar sensory nerve, that is most distal feet sensory-nerves.

RESULTS

Nerve conduction test (NCT) irregularities of dorsal-sural/medial-plantar sensory nerve were considerably greater in patients with prediabetes or diabetes. The means of TNFα levels demonstrated a significant increase in patients with diabetes when compared to prediabetes patients as well as controls showed a significant decrease in patients with prediabetes and diabetes contrasted with controls. No significant contrast with respect to serum biomarkers among patients having regular as well as irregular medial-plantar/dorsal-sural NCT was noted. Critical correlationship among TNFα as well as HbA1c with symptoms severity as well as disability while negative correlations of IL10 with neuropathy severity was noted. Biomarker levels of TNFα, IL10, and HbA1c were noted to differ significantly among patients without/with neuropathy.

CONCLUSION

All in all, the proinflammatory phase appears to start from initial pre-clinical phases, sometime prior to advancement of diabetes. The higher neuropathy frequency in patients with prediabetes indicates conceivable causative impact; although, the prospective part of inflammation in pathogenetics of peripheral neuropathy requires more elucidation.

Levels of Inflammatory Cytokines IL-1β, IL-6, IL-8, IL-17A, and TNF-α in Aqueous Humour of Patients with Diabetic Retinopathy

Diabetic retinopathy is the leading cause of blindness in working age individuals in developed countries. However, the role of inflammation in the pathogenesis of DR is not completely understood. This is an observational clinical research enrolling 80 type II diabetic patients who had undergone cataract surgeries either with DR or without DR. All cases were further categorized by the proliferative stages of retinal neovascularization and by the lengths of diabetic history. The levels of inflammatory cytokines including IL-1β, IL-6, IL-8, IL-17, and TNF-α in aqueous humour were tested. Results in this study indicated that these cytokine levels were increased in DR patients and might have a synergistic effect on the pathogenesis of this disease. They were also elevated along with the progression of neovascularization, reflecting the severity of DR. The results also suggested that for diabetic patients, the higher these levels are, the sooner retinal complications might appear. In conclusion, the levels of inflammatory cytokines IL-1β, IL-6, IL-8, IL-17A, and TNF-α in aqueous humour may be associated with the pathogenesis, severity, and prognosis of DR.

Roles of miRNAs and long noncoding RNAs in the progression of diabetic retinopathy

Diabetic retinopathy (DR) is the leading cause of blindness in working-age adults across the world. The pathogenesis of DR is multifactorial and the molecular mechanisms are still not fully understood. Accumulating evidence has demonstrated that noncoding RNAs (ncRNAs) may be aberrantly expressed and may play vital roles in the development of DR. Amongst ncRNAs, miRNAs and long ncRNAs (lncRNAs) are known for their regulatory functions. Here, we summarize the functions and mechanisms of known aberrantly expressed miRNAs and lncRNAs in DR. Additionally, a novel lncRNA–mRNA–miRNA network is included in this review. We highlight original studies that provide detailed data about the mechanisms of miRNAs and lncRNAs, their applications as diagnostic or prognostic biomarkers, and their potential therapeutic targets. In conclusion, this review will help us gain a better understanding of the molecular mechanisms by which miRNAs and lncRNAs perform their functions in DR, and provide general strategies and directions for future research.

Pemafibrate (K-877), a novel selective peroxisome proliferator-activated receptor alpha modulator for management of atherogenic dyslipidaemia

Despite best evidence-based treatment including statins, residual cardiovascular risk poses a major challenge for clinicians in the twenty first century. Atherogenic dyslipidaemia, in particular elevated triglycerides, a marker for increased triglyceride-rich lipoproteins and their remnants, is an important contributor to lipid-related residual risk, especially in insulin resistant conditions such as type 2 diabetes mellitus. Current therapeutic options include peroxisome proliferator-activated receptor alpha (PPARα) agonists, (fibrates), but these have low potency and limited selectivity for PPARα. Modulating the unique receptor-cofactor binding profile to identify the most potent molecules that induce PPARα-mediated beneficial effects, while at the same time avoiding unwanted side effects, offers a new therapeutic approach and provides the rationale for development of pemafibrate (K-877, Parmodia™), a novel selective PPARα modulator (SPPARMα). In clinical trials, pemafibrate either as monotherapy or as add-on to statin therapy was effective in managing atherogenic dyslipidaemia, with marked reduction of triglycerides, remnant cholesterol and apolipoprotein CIII. Pemafibrate also increased serum fibroblast growth factor 21, implicated in metabolic homeostasis. There were no clinically meaningful adverse effects on hepatic or renal function, including no relevant serum creatinine elevation. A major outcomes study, PROMINENT, will provide definitive evaluation of the role of pemafibrate for management of residual cardiovascular risk in type 2 diabetes patients with atherogenic dyslipidaemia despite statin therapy.

Transcription factor SP1 mediates hyperglycemia-induced upregulation of roundabout4 in retinal microvascular endothelial cells

Roundabout4 (Robo4) is a gene that is expressed specifically in vasculature and is involved in the angiogenesis and integrity of blood vessels. The expression level of Robo4 increases gradually along with the development of diabetic retinopathy (DR). In this study, we explored the mechanism of transcriptional regulation of Robo4 in retinal endothelial cells, and investigated the effects of this regulation on cellular functions under hyperglycemic conditions. Human retinal endothelial cells (HREC) exposed to hyperglycemia were used to detect the expression levels of specificity protein 1 (SP1) and Robo4 by RT-qPCR and western blotting. Small interfering RNA (SiRNA) transfection technology was used to analyze the regulatory relationship between SP1 and Robo4. The effect of transcription factor SP1 on Robo4 promoter activity and the location of SP1 binding sites were investigated using chromatin immunoprecipitation (ChIP) and luciferase assay. Cell migration, monolayer permeability and tube formation assays were performed to demonstrate the role of SP1/Robo4 in regulating HREC functions in hyperglycemic conditions. The results showed that hyperglycemia upregulated the mRNA and protein levels of SP1 and Robo4 in HREC. Depletion of SP1 by siRNA transfection inhibited the hyperglycemia induced overexpression of Robo4. ChIP combined with luciferase assay showed that under hyperglycemic conditions, SP1 significantly increased the transcriptional level of Robo4 via an additional SP1 binding site at -1912/-1908 in the Robo4 promoter. Repressing the SP1/Robo4 pathway effectively mitigated the abnormity in HREC migration, permeability and angiogenesis induced by hyperglycemia. All these findings indicate that hyperglycemia-induced upregulation of Robo4 is mediated by enhanced transcription of SP1. The SP1/Robo4 signaling pathway can regulate the migratory ability, monolayer permeability and angiogenesis of HREC under hyperglycemic conditions, suggesting that it may play an important role in microvascular dysfunction during DR.

Elevated plasma levels of copeptin linked to diabetic retinopathy in type 2 diabetes

BACKGROUND

The arginine vasopressin (AVP) system has been postulated to play a role in glucose homeostasis, insulin resistance, and diabetes mellitus in human and animal studies. The aim of this study was to evaluate the role of plasma copeptin in Chinese patients with type 2 diabetes mellitus (T2DM) with and without diabetic retinopathy (DR).

METHOD

Plasma copeptin concentrations were determined in 281 patients with T2DM. At baseline, demographic and clinical information including presence of DR and vision-threatening DR (VTDR) was collected. The relationship between copeptin and DR or VTDR was investigated using logistic regression.

RESULTS

T2DM participants with DR or VTDR had significantly higher plasma copeptin concentrations on admission (P < 0.0001). Receiver operating characteristics to predict DR and VDTR demonstrated areas under the curve for copeptin of 0.784 (95% confidence interval [CI] 0.724-0.844) and 0.834 (95% CI 0.781-0.904), respectively, which were superior to those for the homeostasis model assessment of insulin resistance (DR AUC 0.736, 95% CI 0.676-0.797; VTDR AUC 0.754, 95% CI 0.703-0.828; P < 0.01). Multivariate logistic regression analysis adjusted for common DR risk factors showed plasma copeptin concentrations ≥28.6 pmol/L (>3rd quartile) to be an independent marker of DR (OR 3.68, 95% CI 2.04-6.79; P < 0.0001) and VTDR (OR 4.32, 95% CI 2.12-8.14; P < 0.0001).

CONCLUSIONS

We found that increased plasma copeptin concentrations were an independent marker of DR and VDTR in Chinese patients with T2DM, suggesting a possible role of copeptin in the pathogenesis of DR complications.

Angiogenesis and Inflammation Crosstalk in Diabetic Retinopathy

Diabetic retinopathy (DR) is one of the most prevalent microvascular complications of diabetes and one of the most frequent causes of blindness in active age. Etiopathogenesis behind this important complication is related to several biochemical, hemodynamic and endocrine mechanisms with a preponderant initial role assumed by polyol pathways, increment of growth factors, accumulation of advanced glycation end products (AGE), activation of protein kinase C (PKC), activation of the renin-angiotensin-aldosterone system (RAAS), and leukostasis. Chronic and sustained hyperglycemia works as a trigger to the early alterations that culminate in vascular dysfunction. Hypoxia also plays an essential role in disease progression with promotion of neovascularization and vascular dystrophies with vitreous hemorrhages induction. Thus, the accumulation of fluids and protein exudates in ocular cavities leads to an opacity augmentation of the cornea that associated to neurodegeneration results in vision loss, being this a devastating characteristic of the disease final stage. During disease progression, inflammatory molecules are produced and angiogenesis occur. Furthermore, VEGF is overexpressed by the maintained hyperglycemic environment and up-regulated by tissue hypoxia. Also pro-inflammatory mediators regulated by cytokines, such as tumor necrosis factor (TNF-α) and interleukin-1 beta (IL-1β), and growth factors leads to the progression of these processes, culminating in vasopermeability (diabetes macular edema) and/or pathological angiogenesis (proliferative diabetic retinopathy). It was found a mutual contribution between inflammation and angiogenesis along the process. J. Cell. Biochem. 117: 2443-2453, 2016. © 2016 Wiley Periodicals, Inc.

Circulating Biomarkers of Diabetic Retinopathy: An Overview Based on Physiopathology

Diabetic retinopathy (DR) is the main cause of working-age adult-onset blindness. The currently available treatments for DR are applicable only at advanced stages of the disease and are associated with significant adverse effects. In early stages of DR the only therapeutic strategy that physicians can offer is a tight control of the risk factors for DR. Therefore, new pharmacological treatments for these early stages of the disease are required. In order to develop therapeutic strategies for early stages of DR new diagnostic tools are urgently needed. In this regard, circulating biomarkers could be useful to detect early disease, to identify those diabetic patients most prone to progressive worsening who ought to be followed up more often and who could obtain the most benefit from these therapies, and to monitor the effectiveness of new drugs for DR before more advanced DR stages have been reached. Research of biomarkers for DR has been mainly based on the pathogenic mechanism involved in the development of DR (i.e., AGEs, oxidative stress, endothelial dysfunction, inflammation, and proangiogenic factors). This review focuses on circulating biomarkers at both early and advanced stages that could be relevant for the prediction or detection of DR.

Molecular Markers of Diabetic Retinopathy: Potential Screening Tool of the Future?

Diabetic retinopathy (DR) is among the leading causes of new onset blindness in adults. Effective treatment may delay the onset and progression of this disease provided it is diagnosed early. At present retinopathy can only be diagnosed via formal examination of the eye by a trained specialist, which limits the population that can be effectively screened. An easily accessible, reliable screening biomarker of diabetic retinopathy would be of tremendous benefit in detecting the population in need of further assessment and treatment. This review highlights specific biomarkers that show promise as screening markers to detect early diabetic retinopathy or even to detect patients at increased risk of DR at the time of diagnosis of diabetes. The pathobiology of DR is complex and multifactorial giving rise to a wide array of potential biomarkers. This review provides an overview of these pathways and looks at older markers such as advanced glycation end products (AGEs), inflammatory markers, vascular endothelial growth factor (VEGF) as well as other newer proteins with a role in the pathogenesis of DR including neuroprotective factors such as brain derived neurotrophic factor (BDNF) and Pigment Epithelium Derived Factor (PEDF); SA100A12, pentraxin 3, brain natriuretic peptide, apelin 3, and chemerin as well as various metabolites such as lipoprotein A, folate, and homocysteine. We also consider the possible role of proteins identified through proteomics work whose levels are altered in the sera of patients with DR as screening markers though their role in pathophysiology remains to be characterized. The role of microRNA as a promising new screening marker is also discussed.

Role of inflammation in sensory neuropathy in prediabetes or diabetes

OBJECTIVES

Prediabetes includes individuals with impaired glucose metabolism, and it has been associated with various complications of diabetes mellitus (DM), including peripheral neuropathy. We aimed to investigate the associations between pro-inflammatory (TNF-α) and anti-inflammatory (IL-10) cytokines and neuropathy of very distal sensory nerves in patients with prediabetes or type 2 DM.

MATERIALS AND METHODS

We included 50 patients with prediabetes, 50 patients with type 2 DM, and 44 controls in the study. Plasma levels of HbA1c, TNF-α, and IL-10 were analyzed. Electrodiagnostic testing was performed on dorsal sural and medial plantar sensory nerves, which are the very distal sensory nerves of the feet.

RESULTS

Abnormalities in nerve conduction studies (NCS) of the dorsal sural and medial plantar sensory nerves were substantially higher in patients with prediabetes or type 2 DM. In addition, plasma levels of TNF-α were significantly higher in patients with type 2 DM than in controls, whereas IL-10 levels were significantly lower in patients with both prediabetes and diabetes. However, we found no correlation between the levels of HbA1c, TNF-α, IL-10, and abnormalities in NCS of the dorsal sural or medial plantar sensory nerves in either patient group.

CONCLUSIONS

To our knowledge, this is the first study to assess the relationships between TNF-α, IL-10, and NCS of the most distal sensory nerves in patients with prediabetes or type 2 DM. The mechanisms involved in the pathogenesis of DM and diabetic peripheral neuropathy are complex. The pro-inflammatory stage and the high incidence of neuropathy in patients with prediabetes may suggest a possible causative effect; however, the potential role of inflammation in the pathogenesis of peripheral neuropathy needs further clarification.

Use of the Monocyte-to-Lymphocyte Ratio to Predict Diabetic Retinopathy

Background: Diabetic retinopathy (DR) is a common complication of type 2 diabetes mellitus (T2DM) and the leading cause of blindness in adults. DR pathogenesis has not been fully elucidated, but inflammation is widely accepted to play an important role. Emerging evidence suggests that the platelet-to-lymphocyte ratio (PLR), monocyte-to-lymphocyte ratio (MLR), and neutrophil-to-lymphocyte ratio (NLR) are novel potential markers of inflammatory responses. The present study aimed to evaluate the associations between DR and the PLR, MLR, and NLR. Patients and Methods: We performed a case-control study involving 247 patients with T2DM. The patients were divided into three groups: 125 control subjects with T2DM, 63 diabetic subjects with non-proliferative diabetic retinopathy (NPDR), and 59 patients with proliferative diabetic retinopathy (PDR). Results: The mean PLR and NLR were significantly higher in patients with DR compared with patients without DR (p < 0.01, p = 0.02, respectively). The mean MLR in the NPDR group was higher than that of patients without DR, but there were no significant differences among the three groups (p = 0.07). Logistic regression showed that the MLR was an independent risk factor for DR (odds ratio [OR]: 54.574, 95% confidence interval [CI]: 2.708–1099.907). Based on the receiver operating characteristic (ROC) curve, use of the MLR as an indicator for DR diagnosis was projected to be 2.25, and yielded a sensitivity and specificity of 47.1% and 69.6%, respectively, with an area under the curve of 0.581 (95% CI: 0.510–0.653). Conclusions: The PLR and NLR are significantly increased in the setting of DR. After correcting for possible confounding factors, the MLR was found to be a risk factor for DR. Although the MLR may be pathophysiologically and clinically relevant in DR, its predictive ability was limited.

Arterial stiffness and endothelial inflammation in prediabetes and newly diagnosed diabetes patients

OBJECTIVE

There is a growing body of data supporting the association between diabetes and microcirculatory disfunction. We aimed to study e-selectin levels, and their associations with serum markers of inflammation and arterial stiffness in prediabetes and newly diagnosed diabetes patients in this study.

SUBJECTS AND METHODS

Sixty patients (25 females) with a newly established elevated fasting serum glucose [20 impaired fasting glucose (IFG), 20 impaired glucose tolerance (IGT), 20 newly diagnosed diabetes (T2DM)] and 17 healthy controls (13 females) were included in the study. Serum e-selectin and hs-CRP levels, and arterial stiffness parameters of the patients were studied.

RESULTS

Fasting serum glucose was the most important predictor of serum e-selectin levels. Pulse wave velocity and central aortic pressures were significantly higher in IFG, IGT and T2DM groups, compared to controls (p = 0.001, < 0.001, 0.013 and 0.015, 0.002, 0.009, respectively). The mean arterial pressure did not show any significant association with serum e-selectin and hs-CRP levels (β coefficient: 0.092, p = 0.358; and β coefficient: 0.189, p = 0.362, respectively).

CONCLUSION

Prediabetes patients have increasing e-selectin levels through the diagnosis of T2DM. E-selectin is associated with serum glucose levels. Prediabetic and newly diagnosed diabetics have higher arterial stiffness measurements. Serum e-selectin may be a good marker of endothelial inflammation and dysfunction increasing in parallel with serum glucose levels, predicting future cardiovascular events.