E En nh ha an nc ce em me en nt t o of f r re ea ac ct ti iv ve e o ox xy yg ge en n s sp pe ec ci ie es s f fo or rm ma at ti io on n i in n s st ta ab bl le e a an nd d u un ns st ta ab bl le e a as st th hm ma at ti ic c p pa at ti ie en nt ts s ABSTRACT: There is increasing evidence to suggest that human blood polymorphonuclear neutrophils (PMNs) and monocytes play an important role in the inflammatory processes of asthma. In asthmatic patients, PMNs and monocytes were shown to be activated more than in healthy subjects. We investigated the capacity of these two cell populations to generate reactive oxygen species (ROS) in stable and unstable asthmatic patients. The two populations of asthmatic patients were identified by asthma activity, as expressed by clinical events occurring within 2 weeks prior to the study. Oxygen species formation was analysed for isolated purified PMNs and monocytes (Mos) by chemiluminescence (CL) using lucigenin and luminol as luminescent probes. CL was determined on nonstimulated and on phorbol myristate acetate (PMA)-stimulated cells. The stimulatability coefficient (PMA-stimulated/nonstimulated cell ratio) of each cell population was then calculated.Resting PMNs and Mos generated significantly greater amounts of ROS in stable asthmatic patients, and much more in unstable asthmatic patients, as compared to healthy subjects, both in lucigenin and luminol enhanced CL. Non O 2 · -ROS production from PMA-stimulated PMNs and Mos was identical in unstable asthmatic patients and in healthy subjects, whereas a significant decrease was observed in stable asthmatic patients, as assessed by luminol enhanced CL. PMA-stimulated cells showed no difference in O 2 · -generation, as assessed by lucigenin enhanced CL. However, the stimulatability coefficient of all asthmatic patients was always significantly lower than that of healthy subjects.These results suggest that there are differences in priming and stimulation of Ros production from PMNs and Mos between stable and unstable asthmatic patients. Release of oxygen species from these cells may be implicated in the pathophysiology of unstable asthma.

Besides eosinophils, inflammatory processes in asthma are characterized by an infiltration of inflammatory cells, including mononuclear phagocytes, such as alveolar macrophages (AM) and blood monocytes, in the airways. Monocyte activation has been observed in the blood after exercise or allergen-induced asthma. Stimulated AM in chronic and stable asthmatic patients have been shown to release oxygen species. We thus investigated the intensity of the activation of monocytes from 18 asthmatic patients compared with 18 healthy subjects. Oxygen species release was analyzed for monocytes in suspension by chemiluminescence using a luminometer and for monocytes maintained in adherence using conventional assay and video imaging camera. Circulating blood monocytes in suspension from asthmatic patients and control subjects showed the same baseline free radical release. Monocytes in suspension from asthmatic patients were more stimulatable by PMA: specifically, monocytes release more H2O and peaks of O2-. are sooner; moreover, peaks of total free radical release are higher, and this plateau is sustained. Compared with monocytes from control subjects, those from asthmatic patients evaluated after adherence show a higher baseline for O2-. and higher total free radical release. Monocytes from asthmatic patients spontaneously release more O2-. over time in nonstimulated cells and release more O2-. with PMA stimulation; they show the same peak level total free radical release as those from control subjects after stimulation. SOD activity analysis on adherent monocytes was lower in asthmatic compared with control subjects. These data show that monocytes from asthmatic patients were activated compared with control monocytes.(ABSTRACT TRUNCATED AT 250 WORDS)

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Some of the beneficial effects of moderate wine consumption may be related to the antioxidant properties of polyphenolic compounds containing tannins, flavonoids, and phenolic acids. Cellular actions have recently been reported and may involve the modulation of transcriptional factors such as AP-1 (activator protein-1), which controls the expression of various genes implicated in inflammation processes, cell differentiation, and proliferation. The aim of this study was to evaluate the modulation of AP-1 activity by the phenolic acids (gallic, caffeic, protocatechic, paracoumaric, sinapic, and ferulic acids) that are present in wine and to compare their modulating pathways to those of lipophilic or hydrophilic "chain-breaking" antioxidants (such as DL-alpha-tocopherol or trolox) vitamin C, nitric oxide, and reduced glutathione. AP-1 response was studied on a cell line (MTLN) derived from MCF-7 cells transfected with luciferase gene under TRE sequence control. After stimulation by phorbol 12-myristate 13-acetate (PMA; 100 nM, 6 h, 10(-7) M), luciferase activity was determined by a luminescence method in the presence of luciferine/coenzyme A solution using a luminometer (LKB 1251, Finland). Antioxidants to be tested were incubated with cells in the presence or absence of PMA. Stimulation with PMA resulted in an AP-1-mediated increase in luciferase gene expression corresponding to an 8-fold increase in luciferase activity. After stimulation by PMA, a dose-dependent inhibition of AP-1 was observed with the six phenolic acids in the 20 nM-20 microM concentration range: gallic acid > caffeic > protocatechic, paracoumaric, sinapic acids > ferulic acid. Inhibition was more pronounced with phenolic acids than with DL-alpha-tocopherol (IC(50) = 5 +/- 4.5 microM for gallic acid vs 85 +/- 11 microM for vitamin E). None of the hydrophilic antioxidants inhibited PMA-induced AP-1 activation. None of the antioxidants tested in the absence of PMA stimulation induced any activation or inhibition of AP-1. Our results suggest that phenolic acids may act directly on cell signaling via inhibition of AP-1 transcriptional activity. In addition to preventing LDL oxidation in the arterial wall, our observations indicate that phenolic acids have a cell-mediated capacity to prevent some of the processes involved in atherosclerosis in a plasma concentration range compatible with nutritional intakes.