Hydrogen peroxide in exhaled air is increased in stable asthmatic children

Exhaled air condensate provides a noninvasive means of obtaining samples from the lower respiratory tract. Hydrogen peroxide (H2O2) in exhaled air has been proposed as a marker of airway inflammation. We hypothesized that in stable asthmatic children the H2O2 concentration in exhaled air condensate may be elevated as a result of airway inflammation. In a cross-sectional study, 66 allergic asthmatic children (of whom, 41 were treated with inhaled steroids) and 21 healthy controls exhaled through a cold trap. The resulting condensate was examined fluorimetrically for the presence of H2O2. All subjects were clinically stable, nonsmokers, without infection. The median H2O2 level in the exhaled air condensate of the asthmatic patients was significantly higher than in healthy controls (0.60 and 0.15 micromol, respectively; p<0.05), largely because of high values in the stable asthmatic children who did not use anti-inflammatory treatment (0.8 micromol; p<0.01 compared to controls). We conclude that hydrogen peroxide is elevated in exhaled air condensate of children with stable asthma, and may reflect airway inflammation

Electrical field stimulation causes oxidation of exogenous histamine in Krebs-Henseleit buffer: A potential source of error in studies of isolated airways

Electric field stimulation (EFS) relaxes human histamine-precontracted airways in vitro. This relaxation is only partly neurally mediated. Nonneural relaxation has been also shown in blood vessels and is due to the generation of oxygen radicals by EFS. In isolated airways the origin of the nonneural component of the relaxation is not clear. Because exogenous catecholamines are oxidized during EPS of carbogenated Krebs-Henseleit (K-H) buffer, we questioned whether this is also the case for exogenous histamine. Human airways precontracted with histamine or methacholine were exposed to either EFS-stimulated carbogenated K-H buffer that also contained histamine or methacholine or unstimulated buffer. Airways exposed to EFS-stimulated buffer that contained histamine relaxed, whereas airways exposed to buffer containing methacholine or exposed to unstimulated buffer did not. It appeared that the histamine concentrations in the organ baths decreased during 30 min of EFS. This decrease was significantly reduced in the presence of ascorbic acid. We conclude that EFS causes oxidation of histamine in carbogenated K-H buffer, and this may at least partly explain the nonneural component of EFS-induced relaxations of precontracted human isolated airways. Therefore, histamine should not be used to induce precontraction in EFS experiments

Hydrogen peroxide in exhaled air of healthy children: reference values

An increased content of hydrogen peroxide (H2O2), a marker of inflammation, has been described in the condensate of exhaled air from adults and children with inflammatory lung disorders, including asthma. However, the normal range of [H2O2] in the exhaled air condensate from healthy children has not been established. Therefore, the aim of this study was to determine the reference range of exhaled [H2O2] in healthy school-aged children. Ninety-three healthy nonsmoking children (48 female and 45 male, mean age 10 yrs, range 8-13 yrs), with a negative history for allergy, eczema or respiratory disease and with a normal lung function, participated. Exhaled air condensate was examined fluorimetrically for the presence of H2O2. In addition, the reproducibility of [H2O2] within subjects and between days and the stability of [H2O2] during storage at -20 degrees C were assessed. The median [H2O2] in the exhaled air condensate of all children was 0.13 microM, with a 2.5-97.5% reference range of <0.01-0.48 microM. No significant difference existed between males and females. There was no correlation between exhaled [H2O2] and age or lung function. Repeated [H2O2] measurements on 2 consecutive days showed satisfactory within-subject reproducibility and [H2O2] in stored samples remained stable for at least 1 month at -20 degrees C. In conclusion, this study provides reference data for exhaled hydrogen peroxide in a large group of healthy children. The observed levels were lower than those reported previously for healthy adults and were independent of age, sex and lung function

Cyclooxygenase activity is important for efficient replication of mouse hepatitis virus at an early stage of infection

Cyclooxygenases (COXs) play a significant role in many different viral infections with respect to replication and pathogenesis. Here we investigated the role of COXs in the mouse hepatitis coronavirus (MHV) infection cycle. Blocking COX activity by different inhibitors or by RNA interference affected MHV infection in different cells. The COX inhibitors reduced MHV infection at a post-binding step, but early in the replication cycle. Both viral RNA and viral protein synthesis were affected with subsequent loss of progeny virus production. Thus, COX activity appears to be required for efficient MHV replication, providing a potential target for anti-coronaviral therapy

Changes in Natural Foxp3+Treg but Not Mucosally-Imprinted CD62LnegCD38+Foxp3+Treg in the Circulation of Celiac Disease Patients

Background:Celiac disease (CD) is an intestinal inflammation driven by gluten-reactive CD4+ T cells. Due to lack of selective markers it has not been determined whether defects in inducible regulatory T cell (Treg) differentiation are associated with CD. This is of importance as changes in numbers of induced Treg could be indicative of defects in mucosal tolerance development in CD. Recently, we have shown that, after encounter of retinoic acid during differentiation, circulating gut-imprinted T cells express CD62LnegCD38+. Using this new phenotype, we now determined whether alterations occur in the frequency of natural CD62L+Foxp3+ Treg or mucosally-imprinted CD62LnegCD38+Foxp3+ Treg in peripheral blood of CD patients. In particular, we compared pediatric CD, aiming to select for disease at onset, with adult CD.Methods:Cell surface markers, intracellular Foxp3 and Helios were determined by flow cytometry. Foxp3 expression was also detected by immunohistochemistry in duodenal tissue of CD patients.Results:In children, the percentages of peripheral blood CD4+Foxp3+ Treg were comparable between CD patients and healthy age-matched controls. Differentiation between natural and mucosally-imprinted Treg on the basis of CD62L and CD38 did not uncover differences in Foxp3. In adult patients on gluten-free diet and in refractory CD increased percentages of circulating natural CD62L+Foxp3+ Treg, but normal mucosally-imprinted CD62LnegCD38+Foxp3+ Treg frequencies were observed.Conclusions:Our data exclude that significant numeric deficiency of mucosally-imprinted or natural Foxp3+ Treg explains exuberant effector responses in CD. Changes in natural Foxp3+ Treg occur in a subset of adult patients on a gluten-free diet and in refractory CD patients

Controlled low flow off line sampling of exhaled nitric oxide in children

BACKGROUND: The aim of this study was to validate exhaled nitric oxide (eNO) values obtained with an alternative off line, single breath, low flow balloon sampling method against on line sampling according to ERS and ATS guidelines in children who could perform both methods. METHODS: One hundred and twenty seven white children of median age 14.1 years, all pupils of a secondary school, participated in the study. They performed the two different sampling techniques at three different flows of 50, 100, 150 ml/s. Additional measurements were done in random subgroups to determine the influence of the dead space air on eNO values obtained off line by excluding the first 220 ml of exhaled air. All children completed a questionnaire on respiratory and allergic disorders and underwent spirometric tests. RESULTS: The off line eNO values were significantly higher than the on line values at all flows. At 50 ml/s the geometric mean (SE) off line eNO was 18.7 (1.1) ppb and the on line eNO was 15.1 (1.1) ppb (p<0.0001). However, when dead space air was discarded, off line and on line values were similar: at 50 ml/s off line eNO was 17.7 (1.0) ppb and on line eNO 16.0 (1.2) ppb. There was a good agreement between off line eNO values without dead space air and on line eNO: for 50 ml/s the mean on/off line ratio was 0.95 (95% agreement limits 0.63 to 1.27). The off line eNO level at 50 ml/s in 80 children with negative questionnaires for asthma, rhinitis, and eczema was 13.6 (1.0) ppb compared with 33.3 (1.1) ppb in the remaining children with positive questionnaires on asthma and allergy and/or recent symptoms of cold (p<0.0001). CONCLUSIONS: In children, off line assessment of eNO using constant low flow sampling and excluding dead space air is feasible and produces similar results as on line assessment with the same exhalation flow rate. Both sampling methods are sufficiently sensitive to differentiate between groups of otherwise healthy school children with and without self-reported asthma, allergy, and/or colds. We propose that, for off line sampling, similar low flow rates should be used as are recommended for on line measurements

Inhibition of cyclooxygenase activity reduces rotavirus infection at a postbinding step.

Elevated levels of prostaglandins (PGs), products of cyclooxygenases (COXs), are found in the plasma and stool of rotavirus-infected children. We sought to determine the role of COXs, PGs, and the signal transduction pathways involved in rotavirus infection to elucidate possible new targets for antiviral therapy. Human intestinal Caco-2 cells were infected with human rotavirus Wa or simian rotavirus SA-11. COX-2 mRNA expression and secreted PGE2 levels were determined at different time points postinfection, and the effect of COX inhibitors on rotavirus infection was studied by an immunofluorescence assay (IFA). To reveal the signal transduction pathways involved, the effect of MEK, protein kinase A (PKA), p38 mitogen-activated protein kinase (MAPK), and NF-kappaB inhibitors on rotavirus infection was analyzed. In infected Caco-2 cells, increased COX-2 mRNA expression and secreted PGE2 levels were detected. Indomethacin (inhibiting both COX-1 and COX-2) and specific COX-1 and COX-2 inhibitors reduced rotavirus infection by 85 and 50%, respectively, as measured by an IFA. Indomethacin reduced virus infection at a postbinding step early in the infection cycle, inhibiting virus protein synthesis. Indomethacin did not seem to affect viral RNA synthesis. Inhibitors of MEK, PKA, p38 MAPK, and NF-kappaB decreased rotavirus infection by at least 40%. PGE2 counteracted the effect of the COX and PKA inhibitors but not of the MEK, p38 MAPK, and NF-kappaB inhibitors. Conclusively, COXs and PGE2 are important mediators of rotavirus infection at a postbinding step. The ERK1/2 pathway mediated by PKA is involved in COX induction by rotavirus infection. MAPK and NF-kappaB pathways are involved in rotavirus infection but in a PGE2-independent manner. This report offers new perspectives in the search for therapeutic agents in treatment of severe rotavirus-mediated diarrhea in children