5 research outputs found
MicroRNA-19a contributes to the epigenetic regulation of tissue factor in diabetes
Background: Diabetes mellitus is characterized by chronic vascular disorder
and presents a main risk factor for cardiovascular mortality. In particular,
hyperglycaemia and inflammatory cytokines induce vascular circulating tissue
factor (TF) that promotes pro-thrombotic conditions in diabetes. It has
recently become evident that alterations of the post-transcriptional
regulation of TF via specific microRNA(miR)s, such as miR-126, contribute to
the pathogenesis of diabetes and its complications. The endothelial miR-19a is
involved in vascular homeostasis and atheroprotection. However, its role in
diabetes-related thrombogenicity is unknown. Understanding miR-networks
regulating procoagulability in diabetes may help to develop new treatment
options preventing vascular complications. Methods and results: Plasma of 44
patients with known diabetes was assessed for the expression of miR-19a, TF
protein, TF activity, and markers for vascular inflammation. High miR-19a
expression was associated with reduced TF protein, TF-mediated
procoagulability, and vascular inflammation based on expression of vascular
adhesion molecule-1 and leukocyte count. We found plasma expression of miR-19a
to strongly correlate with miR-126. miR-19a reduced the TF expression on mRNA
and protein level in human microvascular endothelial cells (HMEC) as well as
TF activity in human monocytes (THP-1), while anti-miR-19a increased the TF
expression. Interestingly, miR-19a induced VCAM expression in HMEC. However,
miR-19a and miR-126 co-transfection reduced total endothelial VCAM expression
and exhibited additive inhibition of a luciferase reporter construct
containing the F3 3′UTR. Conclusions: While both miRs have differential
functions on endothelial VCAM expression, miR-19a and miR-126 cooperate to
exhibit anti-thrombotic properties via regulating vascular TF expression.
Modulating the post-transcriptional control of TF in diabetes may provide a
future anti-thrombotic and anti-inflammatory therapy
Vascular miR‐181b controls tissue factor‐dependent thrombogenicity and inflammation in type 2 diabetes
BACKGROUND:
Diabetes mellitus is characterized by chronic vascular inflammation leading to pathological expression of the thrombogenic full length (fl) tissue factor (TF) and its isoform alternatively-spliced (as) TF. Blood-borne TF promotes factor (F) Xa generation resulting in a pro-thrombotic state and cardiovascular complications. MicroRNA (miR)s impact gene expression on the post-transcriptional level and contribute to vascular homeostasis. Their distinct role in the control of the diabetes-related procoagulant state remains poorly understood.
METHODS:
In a cohort of patients with poorly controlled type 2 diabetes (n = 46) plasma levels of miR-181b were correlated with TF pathway activity and markers for vascular inflammation. In vitro, human microvascular endothelial cells (HMEC)-1 and human monocytes (THP-1) were transfected with miR-181b or anti-miR-181b and exposed to tumor necrosis factor (TNF) α or lipopolysaccharides (LPS). Expression of TF isoforms, vascular adhesion molecule (VCAM) 1 and nuclear factor (NF) κB nuclear translocation was assessed. Moreover, aortas, spleen, plasma, and bone marrow-derived macrophage (BMDM)s of mice carrying a deletion of the first miR-181b locus were analyzed with respect to TF expression and activity.
RESULTS:
In patients with type 2 diabetes, plasma miR-181b negatively correlated with the procoagulant state as evidenced by TF protein, TF activity, D-dimer levels as well as markers for vascular inflammation. In HMEC-1, miR-181b abrogated TNFα-induced expression of flTF, asTF, and VCAM1. These results were validated using the anti-miR-181b. Mechanistically, we confirmed a miR-181b-mediated inhibition of importin-α3 (KPNA4) leading to reduced nuclear translocation of the TF transcription factor NFκB. In THP-1, miR-181b reduced both TF isoforms and FXa generation in response to LPS due to targeting phosphatase and tensin homolog (PTEN), a principal inducer for TF in monocytes. Moreover, in miR-181-/- animals, we found that reduced levels of miR-181b were accompanied by increased TF, VCAM1, and KPNA4 expression in aortic tissue as well as increased TF and PTEN expression in spleen. Finally, BMDMs of miR-181-/- mice showed increased TF expression and FXa generation upon stimulation with LPS.
CONCLUSIONS:
miR-181b epigenetically controls the procoagulant state in diabetes. Reduced miR-181b levels contribute to increased thrombogenicity and may help to identify individuals at particular risk for thrombosis
Metformin Is Associated with Reduced Tissue Factor Procoagulant Activity in Patients with Poorly Controlled Diabetes
Purpose: Metformin is the first-line antidiabetic drug and shown to reduce cardiovascular risk independent from its glucose lowering action. Particularly in poorly controlled diabetes, tissue factor (TF) is expressed in the vasculature and accounts for thromboembolic complications. Here, we aimed to assess the effect of metformin on TF activity and markers of vascular inflammation in poorly controlled type 2 diabetes.
Methods: In a cohort of patients with uncontrolled type 2 diabetes (glycosylated hemoglobin 8.39 ± 0.24%, 68.1 ± 2.6 mmol/mol, n = 46) of whom half of the individuals were treated with metformin and the other half did not receive metformin as part of an anti-diabetic combination therapy, we assessed TF activity and markers of vascular inflammation. In vitro, human monocytic cells (THP-1) were exposed to metformin and TF expression measured in the presence and absence of the AMP-activated protein kinase (AMPK) activator 5-aminoimidazole-4-carboxamide riboside (AICAR) or the AMPK inhibitor compound C.
Results: In the patients, metformin treatment was associated with lower levels of TF protein (241.5 ± 19 vs. 315.4 ± 25 pg/mL, p = 0.03) and reduced TF activity (408.9 ± 49 vs. 643.8 ± 47 U/mL, p = 0.001) compared with controls. Moreover, the patients on metformin showed lower levels of vascular cell adhesion molecule (VCAM)1 (26.6 ± 1.4 vs. 35.03 ± 3.1 ng/mL, p = 0.014) and higher expression of miR-126-3p/U6sno (11.39 ± 2.8 vs. 4.26 ± 0.9, p = 0.006), a known post-transcriptional down regulator of TF and VCAM1. In vitro, metformin dose-dependently reduced lipopolysaccharide (LPS)-induced TF expression in THP-1 cells. The AMPK activator AICAR alone lowered TF expression in THP-1, while the AMPK inhibitor compound C abrogated the metformin-dependent reduction in TF expression.
Conclusions: Our data are the first to report that metformin is associated with reduced plasma TF procoagulant activity possibly explaining-at least in part-the vasculoprotective properties of metformin