Association of monocyte tumor necrosis factor α expression and serum inflammatory biomarkers with walking impairment in peripheral artery disease.

OBJECTIVE: Inflammation contributes to the development of peripheral artery disease (PAD) and may contribute to intermittent claudication by adversely affecting vascular and skeletal muscle function. We explored the association of inflammation to maximal walking time (MWT) in patients with claudication. METHODS: Circulating inflammatory biomarkers, including tumor necrosis factor α (TNF-α), C-reactive protein (CRP), interleukin-6 (IL-6), and soluble intercellular adhesion molecule 1 (sICAM), were measured in 75 subjects with intermittent claudication as well as in 43 healthy subjects. Real-time polymerase chain reaction was used to quantify mRNA expression of TNF-α, IL-6, interferon-γ, and CD36 from peripheral blood monocytes. Treadmill testing was performed in PAD subjects to assess MWT. RESULTS: Compared with healthy subjects, PAD subjects had higher levels of circulating TNF-α (P < .0001), CRP (P = .003), sICAM (P < .0001), and IL-6 (P < .0001). Expression of both IL-6 (P = .024) and CD36 (P = .018) was greater in PAD subjects than in healthy subjects. Among subjects with PAD, higher gene expression of TNF-α was associated inversely with MWT (P = .01). MWT was also associated inversely with greater levels of circulating TNF-α (P = .028), CRP (P = .024), IL-6 (P = .03), and sICAM (P = .018). CONCLUSIONS: Systemic inflammation, as indicated by TNF-α inflammatory gene expression in peripheral blood monocytes and by circulating biomarker levels, is associated with impairment in walking time in patients with PAD and intermittent claudication.

The effect of salsalate therapy on endothelial function in a broad range of subjects.

BACKGROUND: Inflammation is fundamental to the development of atherosclerosis. We examined the effect of anti-inflammatory doses of salicylate on endothelium-dependent vasodilation, a biomarker of cardiovascular risk, in a broad range of subjects. METHODS AND RESULTS: We performed a randomized, double-blind, placebo-controlled crossover trial evaluating the effects of 4 weeks of high-dose salsalate (disalicylate) therapy on endothelium-dependent flow-mediated and endothelium-independent vasodilation. Fifty-eight subjects, including 17 with metabolic syndrome, 13 with atherosclerosis, and 28 healthy controls, were studied. Among all subjects, endothelium-dependent flow-mediated vasodilation decreased after salsalate compared with placebo therapy (P=0.01), whereas nitroglycerin-mediated, endothelium-independent vasodilation was unchanged (P=0.97). Endothelium-dependent flow-mediated vasodilation after salsalate therapy was impaired compared with placebo therapy in subjects with therapeutic salicylate levels (n=31, P<0.02) but not in subjects with subtherapeutic levels (P>0.2). CONCLUSIONS: Salsalate therapy, particularly when therapeutic salicylate levels are achieved, impairs endothelium-dependent vasodilation in a broad range of subjects. These data raise concern about the possible deleterious effects of anti-inflammatory doses of salsalate on cardiovascular risk. CLINICAL TRIAL REGISTRATION URL: www.clinicaltrials.gov. Unique Identifiers: NCT00760019 and NCT00762827.

Contrary effects of the receptor tyrosine kinase inhibitor vandetanib on constitutive and flow-stimulated nitric oxide elaboration in humans.

Vascular endothelial growth factor regulates neoplastic angiogenesis through production of endothelium-derived NO. We performed a prospective evaluation of vascular function during treatment with vandetanib, a vascular endothelial growth receptor 2 and 3 receptor tyrosine kinase inhibitor, to determine the effects of vascular endothelial growth receptor signal interruption on endothelial function in humans. Seventeen patients with stage IV breast cancer received dose-escalated vandetanib in combination with low-dose oral chemotherapy. We measured blood pressure, systemic nitrate/nitrite levels, and brachial artery vascular function. In vitro analyses of cultured endothelial cells were performed to determine the effect of vandetanib on NO production, akt(473) phosphorylation, and endothelial NO synthase protein content and membrane localization. Vandetanib treatment for 6 weeks significantly increased blood pressure, decreased resting brachial artery diameter, and decreased plasma systemic nitrate/nitrite levels compared with baseline. Flow-mediated vasodilation was preserved, and no change was noted in nitroglycerin-mediated vasodilation. In vitro, endothelial cell nitrite levels and akt(473) phosphorylation were reduced and vascular endothelial growth receptor 2 levels did not change, but endothelial NO synthase membrane concentration doubled. Vandetanib reduces constitutive NO production and increases blood pressure, yet flow-stimulated NO bioavailability was preserved. Changes in vascular function with tyrosine kinase inhibition are complex and require further study in humans.

Impaired skeletal muscle glucose uptake by [18F]fluorodeoxyglucose-positron emission tomography in patients with peripheral artery disease and intermittent claudication.

OBJECTIVE: Reduced limb perfusion from arterial stenosis does not adequately account for intermittent claudication symptoms in peripheral artery disease (PAD). Insulin resistance is associated with PAD and may contribute to claudication by impairing skeletal muscle metabolism. We aimed to determine whether skeletal muscle glucose uptake, assessed by [(18)F]fluorodeoxyglucose positron emission tomography, is reduced in patients with claudication. METHODS AND RESULTS: Thirty-seven subjects with PAD and claudication and 11 healthy controls underwent [(18)F]fluorodeoxyglucose-positron emission tomography imaging of the legs during hyperinsulinemic-euglycemic clamp. Calf glucose uptake was quantified by graphical Patlak analysis, and whole-body insulin sensitivity was assessed as the glucose disposal rate (M) from the insulin clamp. Compared with healthy controls, PAD subjects were insulin resistant (M=3.4 mg/kg per minute [interquartile range, 2.7 to 4.8] versus 5.0 [3.7 to 6.6], P=0.019). Calf muscle glucose uptake was significantly lower in PAD compared with healthy subjects (48.6±2.6 µmol/kg per minute versus 62.9±6.5 µmol/kg per minute, P=0.009) and correlated with systemic insulin sensitivity (r=0.37, P=0.03) in PAD subjects. These abnormalities persisted even after exclusion of PAD subjects with diabetes. CONCLUSIONS: Patients with claudication have impaired calf muscle glucose uptake. Future studies are required to assess whether calf muscle insulin resistance contributes to exercise limitation in patients with intermittent claudication.