The European Cooperation in Science and Technology (COST) provides an ideal framework to establish multi-disciplinary research networks. COST Action BM1203 (EU-ROS) represents a consortium of researchers from different disciplines who are dedicated to providing new insights and tools for better understanding redox biology and medicine and, in the long run, to finding new therapeutic strategies to target dysregulated redox processes in various diseases. This report highlights the major achievements of EU-ROS as well as research updates and new perspectives arising from its members. The EU-ROS consortium comprised more than 140 active members who worked together for four years on the topics briefly described below. The formation of reactive oxygen and nitrogen species (RONS) is an established hallmark of our aerobic environment and metabolism but RONS also act as messengers via redox regulation of essential cellular processes. The fact that many diseases have been found to be associated with oxidative stress established the theory of oxidative stress as a trigger of diseases that can be corrected by antioxidant therapy. However, while experimental studies support this thesis, clinical studies still generate controversial results, due to complex pathophysiology of oxidative stress in humans. For future improvement of antioxidant therapy and better understanding of redox-associated disease progression detailed knowledge on the sources and targets of RONS formation and discrimination of their detrimental or beneficial roles is required. In order to advance this important area of biology and medicine, highly synergistic approaches combining a variety of diverse and contrasting disciplines are needed.

Chronic pulmonary hypertension is a serious complication of a number of chronic lung and heart diseases. In addition to vasoconstriction, its pathogenesis includes injury to the peripheral pulmonary arteries leading to their structural remodeling. Increased pulmonary vascular synthesis of an endogenous vasodilator, nitric oxide (NO), opposes excessive increases of intravascular pressure during acute pulmonary vasoconstriction and chronic pulmonary hypertension, although evidence for reduced NO activity in pulmonary hypertension has also been presented. NO can modulate the degree of vascular injury and subsequent fibroproduction, which both underlie the development of chronic pulmonary hypertension. On one hand, NO can interrupt vascular wall injury by oxygen radicals produced in increased amounts in pulmonary hypertension. NO can also inhibit pulmonary vascular smooth muscle and fibroblast proliferative response to the injury. On the other hand, NO may combine with oxygen radicals to yield peroxynitrite and other related, highly reactive compounds. The oxidants formed in this manner may exert cytotoxic and collagenolytic effects and, therefore, promote the process of reparative vascular remodeling. The balance between the protective and adverse effects of NO is determined by the relative amounts of NO and reactive oxygen species. We speculate that this balance may be shifted toward more severe injury especially during exacerbations of chronic diseases associated with pulmonary hypertension. Targeting these adverse effects of NO-derived radicals on vascular structure represents a potential novel therapeutic approach to pulmonary hypertension in chronic lung diseases.

Potassium channels are central to the regulation of pulmonary vascular tone. The smooth muscle cells of pulmonary artery display a background K ϩ conductance with biophysical properties resembling those of KCNQ (K V 7) potassium channels. Therefore, we investigated the expression and functional role of KCNQ channels in pulmonary artery. The effects of selective KCNQ channel modulators were investigated on K ϩ current and membrane potential in isolated pulmonary artery smooth muscle cells (PASMCs), on the tension developed by intact pulmonary arteries, and on pulmonary arterial pressure in isolated perfused lungs and in vivo. The KCNQ channel blockers, linopirdine and XE991 [10,10-bis(4-pyridinylmethyl)-9(10H)-anthracenone], inhibited the noninactivating background K ϩ conductance in PASMCs and caused depolarization, vasoconstriction, and raised pulmonary arterial pressure without constricting several systemic arteries or raising systemic pressure. The KCNQ channel openers, retigabine and flupirtine, had the opposite effects. PASMCs were found to express KCNQ4 mRNA, at higher levels than mesenteric artery, along with smaller amounts of KCNQ1 and 5. It is concluded that KCNQ channels, most probably KCNQ4, make an important contribution to the regulation of pulmonary vascular tone, with a greater contribution in pulmonary compared with systemic vessels. The pulmonary vasoconstrictor effect of KCNQ blockers is a potentially serious side effect, but the pulmonary vasodilator effect of the openers may be useful in the treatment of pulmonary hypertension.

The aim was to determine whether increased oxidative stress during the adaptation to chronic intermittent hypoxia (CIH) plays a role in the induction of improved cardiac ischemic tolerance. Adult male Wistar rats were exposed to CIH in a hypobaric chamber (7,000 m, 8 h/day, 5 days/wk, 24-30 exposures). Half of the animals received antioxidant N-acetylcysteine (NAC; 100 mg/kg) daily before the exposure; the remaining rats received saline. Control rats were kept under normoxia and treated in a corresponding manner. One day after the last exposure (and/or NAC injection), anesthetized animals were subject to 20 min of coronary artery occlusion and 3 h of reperfusion for determination of infarct size. In parallel subgroups, biochemical analyses of the left ventricular myocardium were performed. Adaptation to CIH reduced infarct size from 56.7 +/- 4.5% of the area at risk in the normoxic controls to 27.7 +/- 4.9%. NAC treatment decreased the infarct size in the controls to 42.0 +/- 3.4%, but it abolished the protection provided by CIH (to 41.1 +/- 4.9%). CIH decreased the reduced-to-oxidized glutathione ratio and increased the relative amount of PKC isoform-delta in the particulate fraction; NAC prevented these effects. The expression of PKC-epsilon was decreased by CIH and not affected by NAC. Activities of superoxide dismutase, catalase, and glutathione peroxidase were affected by neither CIH nor NAC treatment. It is concluded that oxidative stress associated with CIH plays a role in the development of increased cardiac ischemic tolerance. The infarct size-limiting mechanism of CIH seems to involve the PKC-delta-dependent pathway but apparently not the increased capacity of major antioxidant enzymes.

The possibility that perinatal exposure to hypoxia influences the pulmonary vasculature in adults was tested. Rats born in a hypoxic environment were kept in hypoxia for an additional week after birth. The rats were then raised in atmospheric air, and when adult, they were compared with the rats born and raised in air. Rats (10 wk old) of both groups were exposed to 10% O2 for 2 wk. They were then studied immediately after the exposure and after 2 wk of recovery from the sojourn in the hypoxic environment. The experience of perinatal hypoxia did not affect mean pulmonary arterial blood pressure, right ventricle weight, or the number of muscularized peripheral pulmonary vessels. During exposure to chronic hypoxia in adulthood, both groups developed pulmonary hypertension, which was not affected by previous perinatal hypoxia. The pulmonary vascular responses to acute hypoxic challenges were studied in the preparation of isolated perfused lungs. In both groups of rats, perinatally hypoxic and normoxic, the acute hypoxic vasoconstriction was attenuated immediately after the exposure of adult animals to chronic hypoxia. However, during the recovery from this hypoxic sojourn, the rats born in hypoxia were significantly more reactive to acute lung hypoxia than all other groups of rats studied. It is concluded that the experience of a short period of perinatal hypoxia did not affect the development of hypoxic pulmonary hypertension induced in adulthood. It increased, however, the pulmonary vascular reactivity to acute hypoxic stimuli during the period of recovery from a sojourn in the hypoxic environment in adulthood.