Evaluation of vascular endothelial growth factor levels in tears and serum among diabetic patients

Abstract

Objective Detection of vascular endothelial growth factor (VEGF) levels in ocular tissue may perhaps provide insight into the role of VEGF in the pathogenesis and progression of diabetic retinopathy (DR). The aim of this study was to evaluate the levels of VEGF in tears and serum amongst type 2 diabetes mellitus (DM) patients. Methods A comparative cross-sectional study was conducted between August 2016 and May 2018 involving type 2 DM patients with no DR, non-proliferative DR (NPDR), and proliferative DR (PDR). Tear samples were collected using no.41 Whatman filter paper (Schirmer strips) and 5 mL blood samples were drawn by venous puncture. VEGF levels in tears and serum were measured by enzyme-linked immunosorbent assay. Results A total of 88 type 2 DM patients (no DR: 30 patients, NPDR: 28 patients, PDR: 30 patients) were included in the study. Mean tear VEGF levels were significantly higher in the NPDR and PDR groups (114.4 SD 52.5 pg/mL and 150.8 SD 49.7 pg/mL, respectively) compared to the no DR group (40.4 SD 26.5 pg/mL, p < 0.001). There was no significant difference in the mean serum VEGF levels between the three groups. There was a fair correlation between serum and tear VEGF levels ( p = 0.015, r = 0.263). Conclusion VEGF levels in tears were significantly higher amongst diabetic patients with DR compared to those without DR and were significantly associated with the severity of DR. There was a fair correlation between serum and tear VEGF levels. Detection of VEGF in tears is a good non-invasive predictor test for the severity of DR. A large cohort study is needed for further evaluation.

Inflammatory and angiogenic biomarkers in diabetic retinopathy

“…Some clinical and biochemical biomarkers such glycaemia, HbA1c, blood pressure, blood lipid concentrations, and ocular coherence tomography (OCT) are routinely used as biomarkers in the monitoring of patients with diabetes. Among pro-inflammatory and angiogenic factors, we can single out VEGF which has enabled the development of anti-VEGF treatment ( 14 , 17 , 26 , 36 , 37 , 39 , 54 ). Many other molecules are used in basic science studies investigating the pathogenesis of DR or as surrogate end-points in preclinical studies that explore new therapy options ( 6 , 47 , 48 ).…”

“…Diabetic retinopathy biomarkers which more accurately reflect the pathology of the posterior segment of the eye, are those determined from the AH and vitreous ( 47 , 48 ). However, these are difficult to obtain and entail invasive procedures to collect the sample ( 21 - 23 , 26 - 28 , 31 - 34 , 36 - 39 , 47 , 48 , 51 - 54 , 56 , 57 ).…”

“…Given that inflammation has a significant role in the pathogenesis of DR inflammatory biomarkers have been intensively investigated ( 10 , 17 , 22 , 24 , 44 - 46 , 49 - 52 ). Various pro-inflammatory factors, such as cytokines and chemokines have been identified at increased concentrations in ocular fluid and tissue namely retina, vitreous, AH, and tears as well as systemic circulation that may be useful as potential biomarkers of DR ( 19 - 39 , 52 - 54 , 59 - 77 ).…”

Diabetic Retinopathy and Ocular Melanoma: How Far We Are?

“…However, all tested uveal melanomas expressed VEGF mRNA [189]. In another study, and always using healthy eye samples as a control, high levels of VEGF were also found in vitreous and anterior chamber fluids of affected eyes [192]. In several studies, including the study by Missotten et al, higher VEGF concentrations have also been reported in the aqueous humour of the affected eyes, possibly justifying the larger basal diameter and the height of the uveal melanoma.…”

Association of vascular endothelial growth factor A gene (VEGFA) polymorphisms, rs699947 and rs1570360, with diabetic retinopathy and altered VEGF secretion in Pakistani patients with Type 2 diabetes mellitus: A case-control study

“…Therefore, increased serum levels of VEGF are an important tool for risk evaluation in diabetic retinopathy. Its serum and vitreous levels correlate with severity of disease [16,17]. Inflammation is a key component in diabetes-associated retinal damages.…”