Comparison of HIF-1α and survivin levels in patients with diabetes and retinopathy of varying severity.

PURPOSE: This study measured serum hypoxia--inducible factor-1 (HIF-1α) and survivin levels in patients with diabetes and investigated their association with the severity of retinopathy. METHODS: This study included 88 patients with type 2 diabetes mellitus who underwent routine eye examinations. Three groups were created. Group 1 consisted of patients without diabetic retinopathy. Group 2 included patients with non-proliferative diabetic retinopathy. Group 3 included patients with proliferative diabetic retinopathy. To measure serum HIF-1α and survivin levels, venous blood samples were collected from patients. RESULTS: The mean HIF-1α levels in groups 1, 2, and 3 were 17.30 ± 2.19, 17.79 ± 2.34, and 14.19 ± 2.94 pg/ml, respectively. Significant differences were detected between groups 1 and 3 (p=0.01) and between groups 2 and 3 (p=0.01). The mean survivin levels in groups 1, 2, and 3 were 42.65 ± 5.37, 54.92 ± 5.55, and 37.46 ± 8.09 pg/ml, respectively. A significant difference was only detected between groups 2 and 3 (p=0.002). CONCLUSION: The present study revealed that serum HIF-1α and survivin levels are increased in patients with non-proliferative diabetic retinopathy compared to those in patients without diabetic retinopathy.

Association of the systemic immuno-inflammation index, neutrophil-to-lymphocyte ratio, and platelet-to-lymphocyte ratio with diabetic microvascular complications.

Background: The systemic immuno-inflammation index (SII), neutrophil-to-lymphocyte ratio (NLR), and platelet-to-lymphocyte ratio (PLR) are widely used and have been shown to be predictive indicators of various diseases. Diabetic nephropathy (DN), retinopathy (DR), and peripheral neuropathy (DPN) are the most prominent and common microvascular complications, which have seriously negative impacts on patients, families, and society. Exploring the associations with these three indicators and diabetic microvascular complications are the main purpose. Methods: There were 1058 individuals with type 2 diabetes mellitus (T2DM) in this retrospective cross-sectional study. SII, NLR, and PLR were calculated. The diseases were diagnosed by endocrinologists. Logistic regression and subgroup analysis were applied to evaluate the association between SII, NLP, and PLR and diabetic microvascular complications. Results: SII, NLR, and PLR were significantly associated with the risk of DN [odds ratios (ORs): 1.52, 1.71, and 1.60, respectively] and DR [ORs: 1.57, 1.79, and 1.55, respectively] by multivariate logistic regression. When NLR ≥2.66, the OR was significantly higher for the risk of DPN (OR: 1.985, 95% confidence interval: 1.29-3.05). Subgroup analysis showed no significant positive associations across different demographics and comorbidities, including sex, age, hypertension, HbA1c (glycated hemoglobin), and dyslipidemia. Conclusion: This study found a positive relationship between NLR and DN, DR, and DPN. In contrast, SII and PLR were found to be only associated with DN and DR. Therefore, for the diagnosis of diabetic microvascular complications, SII, NLR and PLR are highly valuable.

The non-linear relationship between serum albumin and diabetic retinopathy in type 2 diabetes mellitus: a secondary analysis based on a cross-sectional study.

BACKGROUND: Most studies had shown a linear relationship between serum albumin (sALB) and the prevalence of diabetic retinopathy (DR). Thus, the purpose of this study is to investigate whether their relationship is non-linear. METHODS: We included 426 patients with type 2 diabetes who were hospitalized in Guangdong Provincial People's Hospital from December 2017 to November 2018. The outcome was the prevalence of DR. A two-piecewise logistics regression model was performed to identify the non-linear relationship between sALB and the prevalence of DR. The inflection point was calculated to determine the saturation effect through the maximum likelihood ratio and a recursive algorithm. RESULTS: DR was diagnosed in 167 of 426 type 2 diabetic patients. The relationship between sALB and DR was nonlinear. When sALB was less than 38.10 g/L, a significant negative association was observed (OR = 0.82; 95% CI, 0.72-0.94; P = 0.0037), while no significant association was observed when sALB was greater than 38.10 g/L (OR = 1.12; 95% CI, 0.92-1.35; P = 0.2637). CONCLUSIONS: The relationship between sALB and the prevalence of DR is non-linear. sALB is negatively associated with the prevalence of DR when sALB is less than 38.10 g/L. Our findings need to be confirmed by further prospective research.

Joint modeling of time to diabetic retinopathy and change in fasting blood sugar among type 2 diabetic patients, Northwest Ethiopia.

This study aimed to assess changes in fasting blood sugar (FBS) levels, time to diabetic retinopathy (DR) and its predictors among type 2 diabetes patients in Ethiopia. An institution-based retrospective follow-up study was conducted at the University of Gondar Comprehensive Specialized Hospital. The linear mixed effect model and Cox proportional hazard models were fitted separately, and later, the two models were fitted jointly using R software. Variables with a p value < 0.05 were considered significant predictors in the adjusted analysis. The incidence rate of DR was 2 per 100-person year of observation with a median follow-up time of 90.8 months (IQR 63.4). The current value and rate of change in FBS level were significant predictors of time to DR (AHR = 1.35; 95% CI 1.12-1.63) and (AHR = 1.70; 95% CI 1.21-2.39), respectively. Hypertension (AHR = 2.49; 95% CI 1.32-4.66), taking > 1 antidiabetic oral agent (AHR = 4.90; 95% CI 1.07-20.0) and more than 10 years duration (AHR = 0.17, 95% CI 0.06-0.46) were predictors of time to DR. This study revealed that the current value of FBS and the rate of FBS change were significantly associated with the time to DR.

Expression of Long Non-Coding RNA (lncRNA) SNHG5 in Patients with Refractory Diabetic Macular Edema and Its Regulatory Mechanism.

BACKGROUND The aim of this study was to assess use of lncRNAs as biomarkers in serum and aqueous humor of patients with diabetic macular edema (DME). MATERIAL AND METHODS Optical coherence tomography and fundus photography were used to analyze the retinal features of the patients. RT-qPCR was used to analyze the differential expression of lncRNA snhg5 in patients who have idiopathic macular hole (MH), DME, or refractory DME. The relationship between SNHG5 and the clinical characteristics of the patients was analyzed. The effect of SNHG5 on the hyperplasia and apoptosis of human retino-microvascular endothelial cells (HRMECs) and its mechanism were analyzed in vitro. RESULTS Patients with idiopathic MH developed retinal nerve epithelium rupture and retinal fundus thickening, and patients with DME or refractory DME showed significant macular edema with hemorrhaging. The refractory DME patients improved after treatment but still showed significant macular edema and multiple laser scarring. SNHG5 expression was not only low in the atrial fluid and plasma in DME patients, but also lower in the refractory DME group compared to the idiopathic MH patients. SNHG5 expression in the aqueous humor and plasma was negatively correlated with disease duration, body mass index, and levels of fasting blood glucose, glycated hemoglobin, proteinuria, and glycosuria. In the in vitro experiments, SNHG5 expression was significantly downregulated in high glucose-induced HMECs. After SNHG5 overexpression, cell proliferation, angiogenesis, and VEGF-A protein levels were distinctly downregulated. CONCLUSIONS SNHG5 correlates with the development of DME and is a potential target for therapy.

Hypermethylation of miRNA-17-92 cluster in peripheral blood mononuclear cells in diabetic retinopathy.

BACKGROUND AND AIMS: Diabetic retinopathy (DR) is the most common complication of diabetes. The inflammatory milieu of diabetes results in changes throughout the body. This study asked whether epigenetic changes in peripheral blood mononuclear cells (PBMCs) reflect DR severity. METHODS: PBMCs were separated from the whole blood of DR individuals using density gradient centrifugation. DNA was isolated, and methylation of micro-RNA (miR)-17-92 cluster was evaluated. RESULTS: We observed that the miR-17-92 cluster was hypermethylated in DR individuals; specifically, this change was most remarkable with proliferative-DR (PDR). CONCLUSIONS: miR-17-92 methylation in PBMCs could help understand DR's pathogenesis and identify individuals at the risk of severe DR for early intervention.

Serum Antithyroglobulin Antibody Levels Are Associated with Diabetic Retinopathy among Euthyroid Type 2 Diabetes Patients: A Hospital-Based, Retrospective Study.

BACKGROUND: Previous studies have revealed that the variation of thyroid indicators may be associated with the risk of diabetic retinopathy (DR) among euthyroid type 2 diabetes (T2D) patients. But the specific conclusions are currently inconsistent. METHODS: This is a hospital-based retrospective survey. We recruited 1,145 euthyroid T2D patients and checked the thyroid function and fundus photographs. The modified Airlie House classification system was used to categorize the stages of DR. The association between thyroid indicators and different stages of DR was analyzed. RESULTS: We divided free triiodothyronine (FT3) into tertiles and found that the prevalence of mild nonproliferative DR (NPDR) was significantly higher in T2, compared with T1 (32.0% vs. 25.2%, p < 0.05). When FT3 was within the level of T2, FT3 could be an independent risk factor for mild NPDR (OR 1.426, 95% CI (1.031, 1.971), p < 0.05). In addition, the prevalence of severe NPDR and proliferative DR (PDR) was significantly higher in thyroglobulin antibody (TgAb) positive group (8.8% vs. 4.1%, p < 0.05) and vice versa (33.3% vs. 18.4%, p < 0.05). TgAb positivity was also an independent risk factor for severe NPDR and PDR (OR 2.212, 95% CI (1.244, 3.934), p < 0.05). CONCLUSIONS: We hardly observed a significant change in DR risk with the elevation or reduction of serum TSH or thyroid hormone within the reference interval. Although the slightly elevated FT3 may be associated to mild NPDR, the extensibility of this result remains to be seen. For T2D patients with euthyroid function, there may be a significant correlation between serum TgAb positivity and severe NPDR and PDR.

High remnant cholesterol level is relevant to diabetic retinopathy in type 2 diabetes mellitus.

BACKGROUND: Diabetic retinopathy (DR) is the primary oculopathy causing blindness in diabetic patients. Currently, there is increasing interest in the role of lipids in the development of diabetic retinopathy, but it remains controversial. Remnant cholesterol (RC) is an inexpensive and easily measurable lipid parameter; however, the relationship between RC and DR in type 2 diabetes mellitus (T2DM) has not been elucidated. This research investigates the relevance between RC levels and DR severity while building a risk prediction model about DR. METHODS: In this single-centre retrospective cross-sectional study. Each hospitalised T2DM patient had no oral lipid-lowering drugs in the past three months, and coronary angiography showed epicardial coronary artery stenosis of less than 50% and completed seven-field stereo photographs, fluorescein fundus angiography, and optical coherence tomography detection. The RC value is calculated according to the internationally recognised formula. Binary logistic regression was used to correct confounding factors, and the receiver operating characteristic (ROC) analysis was used to identify risk factors and assess the nomogram's diagnostic efficiency. RESULTS: A total of 456 T2DM patients were included in the study. The RC levels in the DR team was higher [0.74 (0.60-1.12) mmo/l vs 0.54 (0.31-0.83) mmol/l P < 0.001] in the non-DR team. After adjusting for confounding elements, RC levels are still associated with DR risk (OR = 5.623 95%CI: 2.996-10.556 P < 0.001). The ratio of DR in every stage (except mild non-proliferative diabetic retinopathy) and DME in the high RC level team were further increased compared to the low-level team (all P < 0.001). After ROC analysis, the overall risk of DR was predicted by a nomogram constructed for RC, diabetes duration, and the neutrophil-lymphocyte ratio as 0.758 (95%CI 0.714-0.802 P < 0.001). CONCLUSIONS: High RC levels may be a potential risk factor for diabetic retinopathy, and the nomogram does better predict DR. Despite these essential findings, the limitation of this study is that it is single-centred and small sample size analysis.

Vitamin D Deficiency in Patients with Diabetes in French Guiana: Epidemiology and Relation with Microvascular and Macrovascular Complications.

Vitamin D (VD) insufficiency is common among patients with diabetes in French Guiana. The study aimed to evaluate the prevalence of VD deficiency in the different type of diabetes encountered and to analyze the relationship between VD deficiency and diabetes complications. METHODS: An observational study was conducted between May 2019 and May 2020 in French Guiana, based on data from the CODIAM study (Diabetes Cohort in French Amazonia), describing the characteristics of patients with diabetes mellitus. Among 600 patients enrolled with diabetes, 361 had an available VD assay. RESULTS: The mean 25(OH)VD (hydroxycalciferol) level was 27.9 ng/mL. The level of VD was inversely proportional to the HbA1c (glycated hemoglobin) level. Patients with angina pectoris had a greater proportion of deficiencies VD < 20 ng/mL than those without angina. By contrast, patients with retinopathy had higher vitamin D concentrations than those without retinopathy. There was no association between vitamin D and arteriopathy, stroke, nephropathy and polyneuropathy. VD deficiency was more frequent in women, and in patients with a high school education. CONCLUSION: The prevalence of VD deficiency was high in patients with diabetes in French Guiana, emphasizing the importance of VD supplementation.

Plasma Metabolomics Reveals Metabolic Profiling For Diabetic Retinopathy and Disease Progression.

Backgrounds: Diabetic retinopathy (DR), the main retinal vascular complication of DM, is the leading cause of visual impairment and blindness among working-age people worldwide. The aim of this study was to investigate the difference of plasma metabolic profiles in patients with DR to better understand the mechanism of this disease and disease progression. Methods: We used ultrahigh-performance liquid Q-Exactive mass spectrometry and multivariate statistical analyses to conduct a comprehensive analysis of plasma metabolites in a population with DR and proliferative DR (PDR). A risk score based on the level of the selected metabolite was established and evaluated using the least absolute shrinkage and selection operator regularization logistic regression (LASSO-LR) based machine learning model. Results: 22 differentially expressed metabolites which belonged to different metabolic pathway were identified and confirmed to be associated with the occurrence of DR. A risk score based on the level of the selected metabolite pseudouridine was established and evaluated to strongly associated with the occurrence of DR. Four circulating plasma metabolites (pseudouridine, glutamate, leucylleucine and N-acetyltryptophan) were identified to be differentially expressed between patients with PDR and other patients, and a risk score formula based on these plasma metabolites was developed and assessed to be significantly related to PDR. Conclusions: Our work highlights the possible use of the risk score assessment based on the plasma metabolites not only reveal in the early diagnosis of DR and PDR but also assist in enhancing current therapeutic strategies in the clinic.

Serum and aqueous humor adiponectin levels correlate with diabetic retinopathy development and progression.

PURPOSE: To compare adiponectin (APN) levels in the serum and aqueous humor (AH) and evaluate their association with the development/progression of diabetic retinopathy (DR). METHODS: Diabetic patients with (group 3; n = 59) and without (group 2; n = 39) DR and age- and sex-matched normal subjects (group 1; n = 35) were compared. Duration of diabetes, body mass index, serum HbA1c, vascular endothelial growth factor (VEGF), APN, pentraxin 3 (PTX3), platelet derived growth factor (PDGF), intercellular adhesion molecule-1 (ICAM-1), and APN were measured and analyzed. RESULTS: One hundred and thirty-three participants were included. Compared to patients without diabetes, diabetic patients with DR had significantly elevated average serum APN levels (5.99±3.89 µg/ml versus 3.51±1.44 µg/ml, P = 0.002) and average AH APN levels (10.94±11.74 ng/ml versus 3.65±3.33 ng/ml, P<0.001). Serum APN was significantly correlated with AH APN (R = 0.512, P<0.001) and AH VEGF (R = 0.202, P = 0.020). The log serum APN was significantly correlated with intraocular cytokines, including log APN, log VEGF, log ICAM, log leptin, log PTX3, log PDGF, angiopoietin, C-reactive protein, and interleukins (IL)-5 and IL-10 (P<0.001, P = 0.020, P<0.001, P<0.001, P = 0.001, P<0.001, P = 0.008, P = 0.009, P<0.001, and P = 0.046, respectively). Log serum VEGF showed a significant correlation only with log AH VEGF (P = 0.001). Multivariate logistic analysis was performed to evaluate the association of DR progression and cytokine concentrations; log Serum APN and log AH APN showed good correlation with the DR progression in each model. CONCLUSIONS: AH APN levels correlated well with DR development and progression. Serum APN could be a better marker for estimating intraocular cytokines, including both intraocular APN and VEGF concentrations in clinical field, than serum VEGF in DR patients.

Reverse Cholesterol Transport Pathway and Cholesterol Efflux in Diabetic Retinopathy.

Cholesterol esters, synthesized from cholesterol with long-chain fatty acids, are essential components of plasma lipoproteins and cell membranes that participate in various metabolic processes in the body. Cholesterol can be excreted through the cholesterol reverse transport (RCT) pathway when excessive cholesterol is produced in the extrahepatic cells, which is regulated by the liver X receptor (LXR) and its downstream regulators ATP-binding cassette subfamily A member 1 (ABCA1) and ATP-binding cassette subfamily G member 1 (ABCG1) genes. Abnormal cholesterol metabolism is closely associated with the development of diabetic retinopathy (DR). However, the precise underlying mechanism of the RCT pathway in the pathogenesis of DR is still not fully understood. This review focused on cholesterol metabolism, with a particular emphasis on the RCT pathway and its correlation with the development of DR. Particular attention has been paid to the key regulators of the RCT pathway: LXR, ABCA1, and ABCG1 genes and their potential therapeutic targets in the management of DR.

Relationship of musculoskeletal diseases with microvascular and macrovascular complications in patients with diabetes in Iran.

BACKGROUND AND AIMS: Musculoskeletal manifestations (carpal tunnel syndrome, Dupuytren's contracture, etc.) may occur in poorly controlled and longstanding diabetes. In this study, we evaluated the relationship of musculoskeletal diseases with microvascular and macrovascular complicationsin patients with diabetes. METHODS: A total of 600 patients with diabetes were enrolled in this cross-sectional study. Demographic data and historical records of the patients were retrieved. Musculoskeletal diseases were assessed by clinical examinations and then confirmed by a rheumatologist. RESULTS: Out of the 600 patients with diabetes, 61.5% (369/600) were female and 38.5% (231/600) were male. Diabetic retinopathy, diabetic nephropathy, diabetic peripheral neuropathy, CVA, and diabetes related ischemic heart disease were rated as 43.1%, 33.2%, 7.8%, 7.5%, and 39.6%, respectively. Significant gender differences were observed in the rates of diabetic nephropathy [56.28% for women and 43.71% for men (p value < 0.000)], diabetic peripheral neuropathy [72.34% for women and 27.65% for men (p value < 0.002)], and ischemic heart disease [57.98% for women and 42.01% for men(p value < 0.001)]. CONCLUSION: Musculoskeletal diseases usually occur in patients with poorly controlled and long-term diabetes. Due to the clear association of microvascular complications with musculoskeletal disease, more attention should be paid to the early detection of these complications in patients with diabetes.

Targeting Plasma Kallikrein With a Novel Bicyclic Peptide Inhibitor (THR-149) Reduces Retinal Thickening in a Diabetic Rat Model.

Purpose: To investigate the effect of plasma kallikrein (PKal)-inhibition by THR-149 on preventing key pathologies associated with diabetic macular edema (DME) in a rat model. Methods: Following streptozotocin-induced diabetes, THR-149 or its vehicle was administered in the rat via either a single intravitreal injection or three consecutive intravitreal injections (with a 1-week interval; both, 12.5 µg/eye). At 4 weeks post-diabetes, the effect of all groups was compared by histological analysis of Iba1-positive retinal inflammatory cells, inflammatory cytokines, vimentin-positive Müller cells, inwardly rectifying potassium and water homeostasis-related channels (Kir4.1 and AQP4, respectively), vascular leakage (fluorescein isothiocyanate-labeled bovine serum albumin), and retinal thickness. Results: Single or repeated THR-149 injections resulted in reduced inflammation, as depicted by decreasing numbers and activation state of immune cells and IL-6 cytokine levels in the diabetic retina. The processes of reactive gliosis, vessel leakage, and retinal thickening were only significantly reduced after multiple THR-149 administrations. Individual retinal layer analysis showed that repeated THR-149 injections significantly decreased diabetes-induced thickening of the inner plexiform, inner nuclear, outer nuclear, and photoreceptor layers. At the glial-vascular interface, reduced Kir4.1-channel levels in the diabetic retina were restored to control non-diabetic levels in the presence of THR-149. In contrast, little or no effect of THR-149 was observed on the AQP4-channel levels. Conclusions: These data demonstrate that repeated THR-149 administration reduces several DME-related key pathologies such as retinal thickening and neuropil disruption in the diabetic rat. These observations indicate that modulation of the PKal pathway using THR-149 has clinical potential to treat patients with DME.

The serum fibroblast growth factor 21 is correlated with retinopathy in patients with type 2 diabetes mellitus.

AIMS: despite advances in blood glucose control, the incidence of sight loss has not decreased in patients with diabetes. Several growth factors have been suggested as factors associated with diabetic retinopathy pathogenesis. In the current cross-sectional study, we examined the relationship between FGF21 and retinopathy as a microvascular complication of diabetes. METHODS: Adult patients with type 2 diabetes mellitus (T2DM); were recruited and evaluated for retinopathy. Different clinical and biochemical factors, such as FGF21 were assessed and compared between groups. RESULTS: 91 T2DM patients with retinopathy, 93 T2DM patients without retinopathy, and 86 healthy control subjects were recruited. FGF21 was significantly different between the three groups (P<0.001). In the multivariate logistic regression model obesity, cholesterol, HbA1c, and FGF21 were associated with diabetic retinopathy. ROC curve analysis was used for establishing a cut-off FGF21 concentration to predict diabetic retinopathy. The area under the curve in this model was 0.992. The best cut-off point for predicting retinopathy based on FGF21 was greater than 312 pg/ml, with a sensitivity of 97.80% and specificity of 96.77%. CONCLUSION: FGF21 was associated with diabetic retinopathy and can be suggested as a surrogate diagnostic marker in the diagnosis of this state.

Correlation between Imaging Morphological Findings and Laboratory Biomarkers in Patients with Diabetic Macular Edema.

PURPOSE: To investigate the potential association between peripheral blood biomarkers and morphological characteristics of retinal imaging in patients with diabetic macular edema (DME). METHODS: Participants in this cross-sectional study were 36 consecutive patients (36 eyes) with treatment-naïve DME, who underwent spectral domain-optical coherence tomography (SD-OCT), fundus photography, and fundus fluorescein angiography (FFA). In addition, peripheral blood samples were taken to evaluate full blood count and biochemical parameters. Correlation between imaging characteristics and laboratory parameters was examined. RESULTS: Eyes with central subfield thickness greater than 405 µm presented significantly higher neutrophils/lymphocytes (p = 0.043) and higher lipoprotein (a) compared to eyes with CST < 405 µm (p = 0.003). Presence of hyperreflective foci on SD-OCT was associated with significantly higher white blood cell count (p = 0.028). Ellipsoid zone disruption was associated with significantly lower hematocrit (p = 0.012), hemoglobin (p = 0.009), and red blood cell count (p = 0.026), as well as with higher lipoprotein (a) (p = 0.015). Macular ischemia on FFA was associated with significantly higher monocytes (p = 0.027) and monocytes/HDL (p = 0.019). No significant associations were found between laboratory parameters and subretinal fluid, intraretinal fluid, exudates, cysts, disorganization of inner retinal layers, epiretinal membrane, and external limiting membrane condition. CONCLUSION: Specific imaging morphological characteristics were found to be associated with laboratory parameters in patients with DME. These findings may shed light on the pathophysiology of DME and its correlation with the development of specific clinical signs.

Fenofibrate increases circulating haematopoietic stem cells in people with diabetic retinopathy: a randomised, placebo-controlled trial.

AIM/HYPOTHESIS: In two large RCTs, fenofibrate reduced the progression of diabetic retinopathy. We investigated whether fenofibrate increases circulating haematopoietic stem/progenitor cells (HSPCs), which have vascular properties and have been shown to protect from retinopathy. METHODS: We conducted a 12 week parallel-group RCT comparing fenofibrate vs placebo. Patients with diabetic retinopathy and without other conditions that would affect HSPCs were enrolled at a tertiary diabetes outpatient clinic and randomised to receive fenofibrate or placebo based on a computer-generated sequence. Patients and study staff assessing the outcomes were blinded to group assignment. The primary endpoint was the change in the levels of circulating HSPCs, defined by expression of the stem cell markers CD34 and/or CD133. Secondary endpoints were the changes in endothelial progenitor cells, lipids, soluble mediators and gene expression. We used historical data on the association between HSPCs and retinopathy outcomes to estimate the effect of fenofibrate on retinopathy progression. RESULTS: Forty-two participants with diabetic retinopathy were randomised and 41 completed treatment and were analysed (20 in the placebo group and 21 in the fenofibrate group). Mean age was 57.4 years, diabetes duration was 18.2 years and baseline HbA1c was 60 mmol/mol (7.6%). When compared with placebo, fenofibrate significantly increased levels of HSPCs expressing CD34 and/or CD133. CD34+ HSPCs non-significantly declined in the placebo group (mean ± SD -44.2 ± 31.6 cells/106) and significantly increased in the fenofibrate group (53.8 ± 31.1 cells/106). The placebo-subtracted increase in CD34+ HSPCs from baseline was 30% (99.3 ± 43.3 cells/106; p = 0.027) which, projected onto the relationship between HSPC levels and retinopathy outcomes, yielded an OR of retinopathy progression of 0.67 for fenofibrate vs placebo. Endothelial differentiation of CD34+ cells, estimated by the %KDR (kinase insert domain receptor) expression, was significantly reduced by fenofibrate. Fenofibrate decreased serum triacylglycerols, but the change in triacylglycerols was unrelated to the change in HSPCs. No effect was observed for endothelial progenitor cells, cytokines/chemokines (stromal-cell derived factor-1, vascular endothelial growth factor, monocyte chemoattractant protein-1) and gene expression in peripheral blood mononuclear cells. CONCLUSIONS/INTERPRETATION: Fenofibrate increased HSPC levels in participants with diabetic retinopathy and this mechanism may explain why fenofibrate reduced retinopathy progression in previous studies. TRIAL REGISTRATION: ClinicalTrials.gov NCT01927315.

Correlation of serum delta-like ligand-4 level with the severity of diabetic retinopathy.

BACKGROUND: Diabetic retinopathy (DR) is one of the most serious microvascular complications of type 2 diabetes mellitus (T2DM). Delta-like ligand-4 (DLL4) maintains the normal physiological microenvironment of the retina. However, the relationship between the level of DLL4 and the severity of DR remains unclear. METHODS: We retrospectively analyzed serum DLL4 levels and other laboratory and clinical data in 94 T2DM patients (35 patients without DR [NDR], 32 with non-proliferative DR [NPDR], 27 with proliferative DR [PDR]), and 30 healthy controls. RESULTS: The serum DLL4 level was significantly greater in the NDR group (43.38 ± 16.23 pg/mL), NPDR group (56.57 ± 25.89 pg/mL), and PDR group (74.97 ± 25.28 pg/mL) than in the healthy controls (29.9 ± 8.92 pg/mL; all p < 0.05). Among T2DM patients, the level of DLL4 increased as the severity of DR increased (p < 0.05). Logistic regression analysis demonstrated that DR was positively associated with DLL4, glycosylated hemoglobin (HbA1c), fasting blood glucose (FBG), and duration of T2DM (all p < 0.05). Consistently, receiver operating characteristic (ROC) curve analysis also indicated that DLL4 was a potential candidate biomarker for identifying the severity of DR. CONCLUSIONS: T2DM patients, especially those with DR, have increased serum levels of DLL4. DLL4 may be used as a biomarker and an independent risk factor for DR, and targeting DLL4 may be a potential therapy in patients with DR.

Exendin-4 inhibits high glucose-induced oxidative stress in retinal pigment epithelial cells by modulating the expression and activation of p66Shc.

PURPOSE: Activation of p66Sch, an adaptor protein, is associated with oxidative stress and apoptosis and has been implicated in the pathogenesis of diabetes-induced retinal pigment epithelial cell damage and diabetic retinopathy. Exendin-4 is a glucagon-like protein that protects against diabetic retinopathy, but the mechanism of action is not well understood. This study aimed to investigate whether Exendin-4 could protect against high glucose-induced oxidative stress and apoptosis in the adult human retinal pigment epithelial-19 cell line by modulating levels and activation of p66Shc and to study the underlying mechanisms. MATERIALS AND METHODS: Adult human retinal pigment epithelial-19 cells were cultured under low (5 µM) or high glucose (100 µM) conditions in the presence or absence of Exendin-4 and with or without pre-incubation with Exendin-9-39, a glucagon-like peptide-1 receptor antagonist. RESULTS: In a dose-dependent manner, Exendin-4 inhibited high glucose-induced cell death and decreased levels of reactive oxygen species, lactate dehydrogenase release, and single single-stranded DNA. At the most effective concentration (100 µM), Exendin-4 reduced mitochondrial levels of phospho-p66Shc (Ser36), cytoplasmic levels of cleaved caspase-3 and cytochrome-c, and NADPH oxidase levels in high glucose-treated cells. It also increased levels of glutathione and magnesium superoxide dismutase and protein levels of magnesium superoxide dismutase but downregulated total protein levels of protein kinase-ß and p66Shc and inhibited c-Jun N-terminal kinase phosphorylation in both low- and high glucose-treated cells. All these Exendin-4 effects, however, were inhibited by Exendin-9-39. CONCLUSIONS: Exendin-4 protects against high glucose-induced adult human retinal pigment epithelial-19 cell damage by increasing antioxidants, downregulating NADPH, and inhibiting mitochondria-mediated apoptosis, effects that are associated with the inhibition of c-Jun N-terminal kinase and downregulation of protein kinase-ß and p66Shc.

Association of serum advanced glycation (AGEs) end products, apolipoprotein-B and zinc in severity of T2DM retinopathy.

Advanced glycation end products (AGEs), lipids and lipoproteins and antioxidant enzymes are involved in the development of diabetic retinopathy (DR). AGEs and modified Apolipoprotein-B (Apo-B) lead to the formation of reactive oxygen species causing damage to the retina leading to DR. Zinc has antioxidant properties and protects the retina against reactive oxygen species. The current study aimed to compare the levels of serum AGEs, Apo-B and zinc in non-diabetics and type II diabetics without and with DR. Serum AGEs and Apo-B were measured by ELISA while zinc was measured by atomic absorption spectrophotometry. The impact of all three markers on the severity of DR was calculated, individually as well as together as a model, to determine the relationship of these markers with severity of diabetic retinopathy. Regression analysis showed that AGEs, Apo-B and zinc were all contributing significantly to the severity of DR, together having an 82.8% impact on it (R2=0.828). The model of the three parameters was best fit to indicate the severity of DR (p-value = 0.553). This study provides a basis for further validation of the suggested model with prospective studies which can then be used in clinical setups to predict the individuals at risk.