VEGF-A165b protects against proteinuria in a mouse model with progressive depletion of all endogenous VEGF-A splice isoforms from the kidney

Chronic kidney disease (CKD) is strongly associated with a decrease in the expression of VEGF-A. However, little is known about the contribution of VEGF-A splice isoforms to kidney physiology and pathology. Previous studies suggest that the splice isoform VEGF-A165b (resulting from alternative usage of a 3’ splice site in the terminal exon) is protective for kidney function. We show here, in a quad-transgenic model, that over-expression of VEGF-A165b alone is sufficient to rescue the increase in proteinuria as well as glomerular water permeability in the context of progressive depletion of all VEGF-A isoforms from the podocytes. Ultrastructural studies show that the glomerular basement membrane is thickened, podocyte slit width is increased and sub-podocyte space coverage is reduced when VEGF-A is depleted, all of which are rescued in VEGF-A165b over-expressors. VEGF-A165b restores the expression of PECAM-1 in glomerular endothelial cells and glomerular capillary circumference. Mechanistically, it increases VEGFR2 expression both in vivo and in vitro and down-regulates genes involved in migration and proliferation of endothelial cells, otherwise up-regulated by the canonical isoform VEGF-A165. Our study indicates that manipulation of VEGF-A splice isoforms could be a novel therapeutic avenue in chronic glomerular disease

Role of Vascular Endothelial Growth Factor-A in Diabetic Kidney Disease

Vascular endothelial growth factor-A (VEGF) is required for endothelial cell differentiation and survival. To investigate the renoprotective properties of VEGF in diabetes an inducible Cre-loxP gene targeting system was used to excise VEGF from podocytes of adult mice (VEGFKO). Diabetes was induced by streptozotocin (STZ) at 2.5 weeks of age and VEGFKO was induced by doxycycline (dox) at 3-4 weeks of age. Blood and urine were collected weekly to monitor for hyperglycaemia and proteinuria, respectively. Mice were dissected 8 weeks after diabetes induction or earlier if morbidly ill; twenty percent of the mice in the DM+VEGFKO group died before the surrogate endpoint. Glomerular VEGF mRNA expression was decreased in VEGFKO mice compared to controls. However, DM+VEGFKO mice had significantly greater proteinuria, degrees of glomerular sclerosis, and glomerular cell apoptosis. These results confirm that VEGF is normally upregulated in diabetes but reducing VEGF expression in diabetes causes severe kidney injury.MAS

Vegfa Protects the Glomerular Microvasculature in Diabetes

IP1AImmunopathology of vascular and renal diseases and of organ and celltransplantatio

In vivo corneal confocal microscopy as a novel non-invasive tool to investigate cardiac autonomic neuropathy in Type 1 diabetes

AIMS: To investigate whether small nerve fibre degeneration detected using corneal confocal microscopy is associated with cardiac autonomic neuropathy in people with Type 1 diabetes. METHODS: Thirty-six people with Type 1 diabetes and 20 age- and sex-matched healthy control subjects were enrolled. Tests to determine heart rate response to deep-breathing (expiratory-to-inspiratory ratio), heart rate response to lying-to-stand test (30:15 ratio) and blood pressure response to standing were performed to detect cardiac autonomic neuropathy. Corneal confocal microscopy was performed to assess: corneal nerve density and corneal nerve beadings; branching pattern; and nerve fibre tortuosity. RESULTS: Compared with control participants, participants with Type 1 diabetes had fewer (mean ± SD 45.4 ± 20.2 vs 92.0 ± 22.7 fibres/mm²; P < 0.001) and more tortuous corneal nerve fibres (20 participants with Type 1 diabetes vs four control participants had nerve tortuosity grade 2/3; P = 0.022) and fewer beadings (mean ± SD 15.1 ± 3.5 vs 20.6 ± 5.0; P < 0.001). Of the participants with Type 1 diabetes, 11 met the criteria for the diagnosis of cardiac autonomic neuropathy. Corneal nerve density was significantly lower in participants with cardiac autonomic neuropathy than in those without (mean ± SD 32.8 ± 16.4 vs 51.7 ± 18.9 fibres/mm²; P = 0.008). This difference remained significant after adjustment for age (P = 0.02), gender (P = 0.04), disease duration (P = 0.005), insulin requirement (P = 0.02) and neuropathy disability score (P = 0.04). CONCLUSION: This study suggests that corneal confocal microscopy could represent a new and non-invasive tool to investigate cardiac autonomic neuropathy in people with Type 1 diabetes. Larger studies are required to define the role of corneal confocal microscopy in the assessment of cardiac autonomic neuropathy

The diagnostic accuracy of Neuropad® for assessing large and small fibre diabetic neuropathy

AIMS: Neuropad(®) is a simple visual indicator test, with moderate diagnostic performance for diabetic peripheral neuropathy. As it assesses sweating, which is a measure of cholinergic small nerve fibre function, we compared its diagnostic performance against established measures of both large and, more specifically, small fibre damage in patients with diabetes. METHODS: One hundred and twenty-seven participants (89 without diabetic peripheral neuropathy and 38 with) aged 57 ± 9.7 years underwent assessment with Neuropad, large nerve fibre assessments: (Neuropathy Disability Score, vibration perception threshold, peroneal motor nerve conduction velocity); small nerve fibre assessments: neuropathy symptoms using the Diabetic Neuropathy Symptoms score (corneal nerve fibre length and warm perception threshold). RESULTS: Neuropad has a high sensitivity but moderate specificity against large fibre neuropathy assessments: Neuropathy Disability Score (> 2) 70% and 50%, vibration perception threshold (> 14 V) 83% and 53%, and peroneal motor nerve conduction velocity (< 42 m/s) 81% and 54%, respectively. However, the diagnostic accuracy of Neuropad was significantly improved against corneal nerve fibre length (< 14 mm/mm(2)) with a sensitivity and specificity of 83% and 80%, respectively. Furthermore, the area under the curve for corneal nerve fibre length (85%) was significantly greater than with the Neuropathy Disability Score (66%, P = 0.01) and peroneal motor nerve conduction velocity (70%, P = 0.03). For neuropathic symptoms, sensitivity was 78% and specificity was 60%. CONCLUSIONS: The data show the improved diagnostic performance of Neuropad against corneal nerve fibre length. This study underlines the importance of Neuropad as a practical diagnostic test for small fibre neuropathy in patientsith diabetes