Search

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. 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. 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. Fenofibrate increased HSPC levels in participants with diabetic retinopathy and this mechanism may explain why fenofibrate reduced retinopathy progression in previous studies. ClinicalTrials.gov NCT01927315.

Cardiovascular risk in diabetes is at least in part attributable to defective angiogenesis. Since diabetes negatively affects blood cells involved in angiogenesis, we herein evaluated whether diabetes impairs proangiogenic granulocytes (PAGs). We characterised and quantified PAGs as CD49d+ granulocytes in peripheral blood of participants with type 2 or type 1 diabetes and in non-diabetic control participants. We evaluated PAG antigenic profile and assessed in vitro functional properties of CD49d+ granulocytes using 2D and 3D angiogenesis assays. We also quantified PAGs before and after glucose control with a sodium–glucose cotransporter 2 (SGLT2) inhibitor, dapagliflozin. In parallel, we measured Ly6G+CD49d+ PAGs in streptozotocin-induced type 1-like diabetic mice vs non-diabetic control mice. PAGs were composed of eosinophils (>80%) and neutrophils (

Aim/hypothesis: Monocytes/macrophages play important roles in adipose and vascular tissues and can be polarised as inflammatory M1 or anti inflammatory M2. We sought to analyse monocyte polarisation status in type 2 diabetes which is characterised by chronic inflammation. Methods: We enrolled 60 individuals without diabetes and 53 patients with type 2 diabetes. We quantified standard monocyte subsets defined by cluster of differentiation (CD)14 and CD16. In addition based on the phenotype of polarised macrophages in vitro we characterised and quantified more definite M1 (CD68+CCR2+) and M2 (CX3CR1+CD206+/CD163+) monocytes. We also analysed bone marrow (BM) samples and the effects of granulocyte colony stimulating factor (G CSF) stimulation in diabetic and control individuals. Results: We found no alterations in standard monocyte subsets (classical intermediate and non classical) when comparing groups. For validation of M1 and M2 phenotypes we observed that M2 were enriched in non classical monocytes and had lower TNF a content higher LDL scavenging and lower transendothelial migratory capacity than M1. Diabetic patients displayed an imbalanced M1/M2 ratio compared with the control group attributable to a reduction in M2. The M1/M2 ratio was directly correlated with waist circumference and HbA 1c and among diabetic patients M2 reduction and M1/M2 increase were associated with microangiopathy. A decrease in M2 was also found in the BM from diabetic patients with a relative M2 excess compared with the bloodstream. BM stimulation with G CSF mobilised M2 macrophages in diabetic but not in healthy individuals. Conclusions/interpretation: We show that type 2 diabetes markedly reduces anti inflammatory M2 monocytes through a dysregulation in bone marrow function. This defect may have a negative impact on microangiopathy. © 2013 Springer Verlag Berlin Heidelberg.

Chronic foot ulceration is a severe complication of diabetes, driving morbidity and mortality. The mechanisms underlying delaying wound healing in diabetes are incompletely understood and tools to identify such pathways are eagerly awaited. Wound biopsies were obtained from 75 patients with diabetic foot ulcers. Matched subgroups of rapidly healing (RH, n = 17) and non-healing (NH, n = 11) patients were selected. Proteomic analysis was performed by labelling with isobaric tag for relative and absolute quantification and mass spectrometry. Differentially expressed proteins were analysed in NH vs RH for identification of pathogenic pathways. Individual sample gene/protein validation and in vivo validation of candidate pathways in mouse models were carried out. Pathway analyses were conducted on 92/286 proteins that were differentially expressed in NH vs RH. The following pathways were enriched in NH vs RH patients: apoptosis, protease inhibitors, epithelial differentiation, serine endopeptidase activity, coagulation and regulation of defence response. SerpinB3 was strongly upregulated in RH vs NH wounds, validated as protein and mRNA in individual samples. To test the relevance of serpinB3 in vivo, we used a transgenic mouse model with α1-antitrypsin promoter-driven overexpression of human SERPINB3. In this model, wound healing was unaffected by SERPINB3 overexpression in non-diabetic or diabetic mice with or without hindlimb ischaemia. In an independent validation cohort of 47 patients, high serpinB3 protein content was confirmed as a biomarker of healing improvement. We provide a benchmark for the unbiased discovery of novel molecular targets and biomarkers of impaired diabetic wound healing. High serpinB3 protein content was found to be a biomarker of successful healing in diabetic patients.

A reduction in the number of endothelial progenitor cells (EPCs) is considered a plausible cause of increased cardiovascular risk in diabetes mellitus. The aim of this study was to test the hypothesis that weak bone marrow mobilisation is responsible for the decrease in circulating EPCs in diabetes.We employed a model of hindlimb ischaemia-reperfusion (I/R) injury to study mobilisation of EPCs in control and streptozotocin diabetic rats. EPCs were defined by flow cytometry as Sca-1(+) and Sca-1(+)c-kit(+) peripheral blood cells and further characterised by the expression of CD31, von Willebrand factor and fetal liver kinase-1. Capillary density was evaluated by immunofluorescent staining of vWF. We also determined plasma levels of stromal cell-derived factor (SDF-1) and vascular endothelial growth factor (VEGF) by ELISA and muscle expression of hypoxia-induced factor (HIF-1alpha) by Western blotting.In control rats, EPCs showed a mobilisation curve within 7 days, while diabetic rats were completely unable to mobilise EPCs after I/R injury. As a consequence, diabetic rats showed no compensatory increase in muscle capillary density. Defective EPC mobilisation in diabetes was associated with altered release of SDF-1 and VEGF and inability to upregulate muscle HIF-1alpha. Both insulin administration and premedication with granulocyte-colony stimulating factor and stem cell factor led to partial recovery in post-ischaemic mobilisation of EPCs in diabetic rats.Defective ischaemia-induced bone marrow mobilisation of EPCs impedes compensatory angiogenesis in ischaemic tissues of diabetic animals. Growth factor administration together with blood glucose control may offer a rational therapeutic strategy for diabetic ischaemic syndromes.