Retinol binding protein 3 as biomarker for diabetic retinopathy

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 Retinol Binding Protein 3 Concentrations Are Associated With Decreased Vitreous Inflammatory Cytokines, VEGF, and Progression of Diabetic Retinopathy

OBJECTIVE

To correlate inflammatory cytokines and vascular endothelial growth factor (VEGF) in vitreous and plasma with vitreous retinol binding protein 3 (RBP3), diabetic retinopathy (DR) severity, and DR worsening in a population with type 1 and type 2 diabetes.

RESEARCH DESIGN AND METHODS

RBP3, VEGF, and inflammatory cytokines were measured in plasma and vitreous samples (n = 205) from subjects of the Joslin Medalist Study and Beetham Eye Institute.

RESULTS

Higher vitreous RBP3 concentrations were associated with less severe DR (P < 0.0001) and a reduced risk of developing proliferative DR (PDR) (P < 0.0001). Higher RBP3 correlated with increased photoreceptor segment thickness and lower vitreous interleukin-12 (IL-12), tumor necrosis factor-α (TNF-α), and TNF-β (P < 0.05). PDR was associated with lower vitreous interferon-γ and IL-10 and higher VEGF, IL-6, and IL-15 (P < 0.05), but was not associated with their plasma concentrations.

CONCLUSIONS

Higher vitreous RBP3 concentrations are associated with less severe DR and slower rates of progression to PDR, supporting its potential as a biomarker and therapeutic agent for preventing DR worsening, possibly by lowering retinal VEGF and inflammatory cytokines.

Hyperglycemia-induced increasing of RELB/circ_0008590 in NF-κB pathway is repressed by miR-1243 in human retinal microvascular endothelial cells

BACKGROUND

To investigate the abnormal expression of circ_0008590 and its parent gene, reticuloendotheliosis viral oncogene related B (RELB) in human retinal microvascular endothelial cells (hRECs) in hyperglycemia and the potential mechanism.

METHODS

The levels of RELB, circ_0008590, and miR-1243 in hRECs or clinical samples were detected by quantitative reverse transcription-polymerase chain reaction (qRT-PCR). Dual-luciferase reporter assay was used to test the interaction between RELB/circ_0008590 and miR-1243. Cell Counting Kit-8 (CCK-8), Transwell, flow cytometry (FCM), wound healing, and tube formation assays were used for the physiological investigation. The interaction between human RELB and circ_0008590 was studied in streptozotocin (STZ) induced diabetic retinopathy (DR) C57BL/6 mice.

RESULTS

The levels of circ_0008590 and RELB were increased in hRECs in hyperglycemia; during the progression of DR, the levels of circ_0008590 and RELB messenger RNA (mRNA) in aqueous humor were first decreased and then increased, whereas miR-1243 showed an opposite trend. Both RELB 3'-untranslated region (UTR) and circ_0008590 shared a similar binding site for miR-1243. Further, miR-1243 mimic suppressed the proliferation and migration of hRECs, promoting the apoptosis ratio, which could be rescued by the overexpression of circ_0008590. In STZ-induced DR mice, miR-1243 agomir rescued the effects of the overexpression of human RELB.

CONCLUSIONS

In hyperglycemia, high expression of RELB/circ_0008590 could be suppressed by miR-1243, and the nuclear factor-κB (NF-κB) pathway is subsequently affected.

Discoveries from the study of longstanding type 1 diabetes

Award programmes that acknowledge the remarkable accomplishments of long-term survivors with type 1 diabetes have naturally evolved into research programmes to determine the factors associated with survivorship and resistance to chronic complications. In this review, we present an overview of the methodological sources of selection bias inherent in survivorship research (selection of those with early-onset diabetes, incidence-prevalence bias and bias from losses to follow-up in cohort studies) and the breadth and depth of literature focusing on this special study population. We focus on the learnings from the study of longstanding type 1 diabetes on discoveries about the natural history of insulin production loss and microvascular complications, and mechanisms associated with them that may in future offer therapeutic targets. We detail descriptive findings about the prevalence of preserved insulin production and resistance to complications, and the putative mechanisms associated with such resistance. To date, findings imply that the following mechanisms exist: strategies to maintain or recover beta cells and their function; activation of specific glycolytic enzymes such as pyruvate kinase M2; modification of AGE production and processing; novel mechanisms for modification of renin-angiotensin-aldosterone system activation, in particular those that may normalise afferent rather than efferent renal arteriolar resistance; and activation and modification of processes such as retinol binding and DNA damage checkpoint proteins. Among the many clinical and public health insights, research into this special study population has identified putative mechanisms that may in future serve as therapeutic targets, knowledge that likely could not have been gained without studying long-term survivors.

Clinical and predictive significance of Plasma Fibrinogen Concentrations combined Monocyte-lymphocyte ratio in patients with Diabetic Retinopathy

Diabetic retinopathy (DR) is one of the most common causes of blindness and visual impairment. Therefore, early prediction of its occurrence and progression is important. This study aimed to assess the clinical and predictive significance of plasma fibrinogen concentrations combined monocyte-lymphocyte ratio (FC-MLR) in patients with DR. A total of 307 patients with type 2 diabetes (T2D) were enrolled. Plasma fibrinogen concentrations and peripheral white blood cells were measured, and MLR was calculated, and the associations of FC-MLR with DR and severity of disease were assessed. Regression analysis and receiver operating characteristic (ROC) curves were performed to evaluate the risk factors and predictive power of FC-MLR for DR and severity of disease, respectively. DR patients showed higher fibrinogen concentrations and a higher MLR than did T2D patients without complications (P<0.01); Moreover, DR patients in proliferative stage also showed higher fibrinogen concentrations and a higher MLR than did those in non-proliferative stage (P<0.01). FC-MLR was closely associated with occurrence and severity of DR (P<0.01), and was an independent risk factor for them (OR=6.123, 95%CI: 3.122-17.102; and 7.932, 95%CI: 4.315-16.671, respectively; P<0.001). The predictive sensitivity and specificity for DR and severity of disease were 0.86 and 0.68, and 0.85 and 0.73, respectively. The study suggests that FC-MLR may be used as a predictor for the risk and progression of diabetic retinopathy.