Objective-Inflammatory processes and foam cell formation are key determinants in the initiation and progression of atherosclerosis. Electrophilic nitro-fatty acids, byproducts of nitric oxide-and nitrite-dependent redox reactions of unsaturated fatty acids, exhibit antiinflammatory signaling actions in inflammatory and vascular cell model systems. The in vivo action of nitro-fatty acids in chronic inflammatory processes such as atherosclerosis remains to be elucidated. Methods and Results-Herein, we demonstrate that subcutaneously administered 9-and 10-nitro-octadecenoic acid (nitro-oleic acid) potently reduced atherosclerotic lesion formation in apolipoprotein E-deficient mice. Nitro-fatty acids did not modulate serum lipoprotein profiles. Immunostaining and gene expression analyses revealed that nitro-oleic acid attenuated lesion formation by suppressing tissue oxidant generation, inhibiting adhesion molecule expression, and decreasing vessel wall infiltration of inflammatory cells. In addition, nitro-oleic acid reduced foam cell formation by attenuating oxidized low-density lipoprotein-induced phosphorylation of signal transducer and activator of transcription-1, a transcription factor linked to foam cell formation in atherosclerotic plaques. Atherosclerotic lesions of nitro-oleic acid-treated animals also showed an increased content of collagen and ␣-smooth muscle actin, suggesting conferral of higher plaque stability. Conclusion-These

Myeloid cells play a pivotal role in regulating innate and adaptive immune responses. In inflammation, autoimmunity, and after transplantation, myeloid cells have contrasting roles: on the one hand they initiate the immune response, promoting activation and expansion of effector T-cells, and on the other, they counter-regulate inflammation, maintain tissue homeostasis, and promote tolerance. The latter activities are mediated by several myeloid cells including polymorphonuclear neutrophils, macrophages, myeloid-derived suppressor cells, and dendritic cells. Since these cells have been associated with immune suppression and tolerance, they will be further referred to as myeloid regulatory cells (MRCs). In recent years, MRCs have emerged as a therapeutic target or have been regarded as a potential cellular therapeutic product for tolerance induction. However, several open questions must be addressed to enable the therapeutic application of MRCs including: how do they function at the site of inflammation, how to best target these cells to modulate their activities, and how to isolate or to generate pure populations for adoptive cell therapies. In this review, we will give an overview of the current knowledge on MRCs in inflammation, autoimmunity, and transplantation. We will discuss current strategies to target MRCs and to exploit their tolerogenic potential as a cell-based therapy.

Endothelial dysfunction characterized by decreased nitric oxide (NO) bioavailability is the first stage of coronary artery disease. It is known that one of the factors associated with an increased risk of coronary artery disease is a high plasma level of uric acid. However, causative associations between hyperuricaemia and cardiovascular risk have not been definitely proved. In this work, we tested the effect of uric acid on endothelial NO bioavailability. Electrochemical measurement of NO production in acetylcholine-stimulated human umbilical endothelial cells (HUVECs) revealed that uric acid markedly decreases NO release. This finding was confirmed by organ bath experiments on mouse aortic segments. Uric acid dose-dependently reduced endothelium-dependent vasorelaxation. To reveal the mechanism of decreasing NO bioavailability we tested the effect of uric acid on reactive oxygen species production by HUVECs, on arginase activity, and on acetylcholine-induced endothelial NO synthase phosphorylation. It was found that uric acid increases arginase activity and reduces endothelial NO synthase phosphorylation. Interestingly, uric acid significantly increased intracellular superoxide formation. In conclusion, uric acid decreases NO bioavailability by means of multiple mechanisms. This finding supports the idea of a causal association between hyperuricaemia and cardiovascular risk.

Pulmonary arterial hypertension (PAH) is characterized by adverse remodeling of pulmonary arteries. Although the origin of the disease and its underlying pathophysiology remain incompletely understood, inflammation has been identified as a central mediator of disease progression. Oxidative inflammatory conditions support the formation of electrophilic fatty acid nitroalkene derivatives, which exert potent anti-inflammatory effects. The current study investigated the role of 10-nitro-oleic acid (OA-NO 2 ) in modulating the pathophysiology of PAH in mice. Mice were kept for 28 days under normoxic or hypoxic conditions, and OA-NO 2 was infused subcutaneously. Right ventricular systolic pressure (RVPsys) was determined, and right ventricular and lung tissue was analyzed. The effect of OA-NO 2 on cultured pulmonary artery smooth muscle cells (PASMCs) and macrophages was also investigated. Changes in RVPsys revealed increased pulmonary hypertension in mice on hypoxia, which was significantly decreased by OA-NO 2 administration. Right ventricular hypertrophy and fibrosis were also attenuated by OA-NO 2 treatment. The infiltration of macrophages and the generation of reactive oxygen species were elevated in lung tissue of mice on hypoxia and were diminished by OA-NO 2 treatment. Moreover, OA-NO 2 decreased superoxide production of activated macrophages and PASMCs in vitro. Vascular structural remodeling was also limited by OA-NO 2 . In support of these findings, proliferation and activation of extracellular signal-regulated kinases 1/2 in cultured PASMCs was less pronounced on application of OA-NO 2 . Our results show that the oleic acid nitroalkene derivative OA-NO 2 attenuates hypoxia-induced pulmonary hypertension in mice. Thus, OA-NO 2 represents a potential therapeutic agent for the treatment of PAH.Keywords: pulmonary arterial hypertension; nitro-fatty acids; inflammation; hypoxia Clinical RelevancePulmonary hypertension is a severe disease whose pathophysiology is incompletely understood and for which therapeutic options are limited. The present study enforces the hypothesis that inflammatory and oxidative mechanisms play an important role in the development of pulmonary hypertension. Electrophilic nitro-fatty acids decreased hypoxia-induced pulmonary hypertension not only by antiinflammatory and antioxidant mechanisms but also by reducing smooth muscle cell proliferation via attenuation of extracellular signal-regulated kinases 1 and 2 activation. These findings suggest that nitro-fatty acids may serve as a new multimodal therapeutic approach in this disease.

Background-The nitric oxide synthase inhibitor asymmetrical dimethylarginine (ADMA) and the leukocyte-derived hemoprotein myeloperoxidase (MPO) are associated with cardiovascular diseases. Activation of monocytes and polymorphonuclear neutrophils (PMNs) with concomitant release of MPO is regulated in a nitric oxide-dependent fashion. The aim of the study was to investigate a potential 2-way interaction between ADMA and MPO. Methods and Results-Ex vivo, ADMA uptake by isolated human PMNs, the principal source of MPO in humans, significantly impaired nitric oxide synthase activity determined by gas chromatography-mass spectrometry. In humans, short-term ADMA infusion (0.0125 mg ⅐ kg Ϫ1 ⅐ min Ϫ1 ) significantly increased MPO plasma concentrations. Functionally, PMN exposure to ADMA enhanced leukocyte adhesion to endothelial cells, augmented NADPH oxidase activity, and stimulated PMN degranulation, resulting in release of MPO. In vivo, a 28-day ADMA infusion (250 mol ⅐ kg Ϫ1 ⅐ d Ϫ1 ) in C57Bl/6 mice significantly increased plasma MPO concentrations, whereas this ADMA effect on MPO was attenuated by human dimethylarginine dimethylaminohydrolase1 (hDDAH1) overexpression. Moreover, the MPO-derived reactive molecule hypochlorous acid impaired recombinant hDDAH1 activity in vitro. In MPO Ϫ/Ϫ mice, the lipopolysaccharide-induced increase in systemic ADMA concentrations was abrogated. Conclusions-ADMA profoundly impairs nitric oxide synthesis of PMNs, resulting in increased PMN adhesion to endothelial cells, superoxide generation, and release of MPO. In addition, MPO impairs DDAH1 activity. Our data reveal an ADMA-induced cycle of PMN activation, enhanced MPO release, and subsequent impairment of DDAH1 activity. These findings not only highlight so far unrecognized cytokine-like properties of ADMA but also identify MPO as a regulatory switch for ADMA bioavailability under inflammatory conditions. (Circulation. 2011;124:2735-2745.)