Cardiovascular BDNF is mainly localized within endothelial cells in which its expression is dependent on endothelial function. These results open new perspectives on the role of endothelial BDNF in cardiovascular health.

Polyphenols are plant secondary metabolites which possess many positive effects on human health. Although these beneficial effects could be mediated through an increase in nitric oxide synthase activity, little is known regarding the inhibitory effect of polyphenols on mammal arginase, an enzyme which competes with nitric oxide synthase for their common substrate, L-arginine. The aim of the present study was to determine the potential of a series of polyphenols as mammalian arginase inhibitors and to identify some structure-activity relationships. For this purpose, we first developed a simple and cost-effective colorimetric microplate method using commercially-available mammal bovine liver arginase (b-ARG 1). Among the ten tested polyphenolic compounds [chlorogenic acid, piceatannol, resveratrol, (-)-epicatechin, taxifolin, quercetin, fisetin, caffeic acid, quinic acid, and kaempferol], cholorogenic acid and piceatannol exhibited the highest inhibitory activities (IC = 10.6 and 12.1 µM, respectively) but were however less active as ()-(2-Boronoethyl)-L-cysteine (IC = 3.3 µM), used as reference compound. Enzyme kinetic studies showed that both chlorogenic acid and piceatannol are competitive arginase inhibitors. Structural data identified the importance of the caffeoyl (3,4-dihydroxycinnamoyl)-part and of the catechol function in the inhibitory activity of the tested compounds. These results identified chlorogenic acid and piceatannol as two potential core structures for the design of new arginase inhibitors.

ObjectivesTo determine mechanisms involved in endothelial dysfunction (ED) during the course of arthritis and to investigate the link between cytokines, chemokines and osteoprotegerin.Approach and ResultsExperiments were conducted on aortic rings at day 4 (preclinical), day 11 (onset of disease), day 33 (acute disease) and day 90 (chronic disease) after adjuvant-induced arthritis (AIA) in Lewis rats. At day 4, the unique vascular abnormality was a reduced norepinephrine-induced constriction. At day 11, endothelial function assessed by the relaxation to acetylcholine was normal despite increased cyclo-oxygenase-2 activity (COX-2) and overproduction of superoxide anions that was compensated by increased nitric oxide synthase (NOS) activity. At day 33, ED apparition coincides with the normalization of NOS activity. At day 90, ED was only observed in rats with a persisting imbalance between endothelial NOS and COX-2 pathways and higher plasma levels of IL-1β and TNFα. Plasma levels of IL-1β, TNFα and MIP-1α negatively correlated with Ach-induced relaxation throughout the course of AIA.ConclusionsOur data identified increased endothelial NOS activity as an important compensatory response that opposes the ED in the early arthritis. Thereafter, a cross-talk between endothelial COX-2/NOS pathways appears as an important element for the occurrence of ED. Our results encourage determining the clinical value of IL-1β, TNFα and MIP-1α as biomarkers of ED in RA.

Objective. To determine the time course of microvascular abnormalities and the link with macrovascular endothelial function and circulating markers of endothelial activation in adjuvant-induced arthritis (AIA) in rats.Methods. Microvascular function/structure and mechanics were studied in third-order mesenteric arteries subjected to flow and/or pressure on day 4 (preclinical arthritis), day 11 (very early arthritis), day 33 (severe disease), and day 90 (when inflammation has resolved) after AIA induction. Macrovascular function was studied in aortic rings, and blood pressure, plasma levels of C-reactive protein (CRP), intercellular adhesion molecule 1 (ICAM-1), and vascular cell adhesion molecule 1 (VCAM-1) were measured at each time point.Results. Mesenteric flow-mediated vasodilation was significantly reduced from very early arthritis to chronic disease, whereas increased microvascular arterial stiffness was evident only on day 33. Macrovascular endothelial dysfunction was observed only on day 33. Thus, on day 90, whereas rats with AIA recovered normal macrovascular endothelial function, microvascular endothelial function remained impaired. No correlation was found between micro-and macrovascular endothelial function throughout the course of arthritis (r 5 0.180, P 5 0.229). Furthermore, no correlation was found between CRP levels, ICAM-1 levels, and endothelial function whatever the vascular bed. AIA was not associated with change in blood pressure or VCAM levels.Conclusion. Our findings indicate that microvascular endothelial dysfunction occurs earlier than macrovascular endothelial dysfunction and microvascular arterial stiffness during arthritis, suggesting that microvascular endothelial function would be a valuable tool for the early assessment of cardiovascular risk in RA. Neither the ICAM-1 level nor the CRP level is a good marker of micro-or macrovascular endothelial dysfunction.

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