The immune system is regulated to protect the host from exaggerated stimulatory signals establishing a state of tolerance in healthy individuals. The disequilibrium in immune regulatory vs effector ...mechanisms results in allergic or autoimmune disorders in genetically predisposed subjects under certain environmental conditions. As demonstrated in allergen‐specific immunotherapy and in the healthy immune response to high‐dose allergen exposure models in humans, T regulatory cells are essential in the suppression of Th2‐mediated inflammation, maintenance of immune tolerance, induction of the two suppressive cytokines interleukin‐10 and transforming growth factor‐β, inhibition of allergen‐specific IgE, and enhancement of IgG4 and IgA. Also, suppression of dendritic cells, mast cells, and eosinophils contributes to the construction of peripheral tolerance to allergens. This review focuses on mechanisms of peripheral tolerance to allergens with special emphasis on recent developments in the area of immune regulation.
Background
Indoleamine 2,3‐dioxygenase (IDO), which degrades tryptophan (Trp) to kynurenine (Kyn), has been demonstrated to contribute to modulation of allergic responses. However, the role of IDO in ...food allergy has not yet been elucidated.
Methods
Serum Trp and Kyn concentrations were analyzed by high‐pressure liquid chromatography. Expression of IDO gene was measured by real‐time PCR. The levels of interleukin (IL)‐4, IL‐10, and interferon (IFN)‐γ in cell culture supernatants were measured by ELISA.
Results
Kyn/Trp (IDO activity) was significantly lower in subjects with food allergy (n = 100) than in aged‐matched healthy controls (n = 112) (P = 0.004). Kyn/Trp was decreased from healthy through completely tolerant, partially tolerant, and reactive ones LN transformation (mean ± SEM) healthy: 3.9 ± 0.02 μM/mM; completely tolerant: 3.83 ± 0.04; partially tolerant: 3.8 ± 0.06; reactive: 3.7 ± 0.04 (P = 0.008). The frequency of genetic polymorphisms of IDO did not reveal a significant association with Trp, Kyn, and Kyn/Trp in healthy and food‐allergic cases. Culture of PBMC experiments yielded that IDO mRNA expression was not different between tolerant and reactive groups. IL‐4 synthesis when stimulated with casein increased significantly in subjects who are reactive and tolerant to foods (P = 0.042, P = 0.006, respectively). Increase in IL‐10 synthesis was observed only in children tolerant to milk, but not in reactive ones. IFN‐γ synthesis, when stimulated with IL‐2 and β‐lactoglobulin in cell culture, was significantly higher in subjects tolerant to milk than in the reactive ones (P = 0.005 and P = 0.029, respectively).
Conclusion
Our results imply the probability of involvement of IDO in development of tolerance process, and we presume that high IDO activity is associated with nonresponsiveness to food allergens despite allergen sensitization.
There is ample evidence for the existence of a systemic oxidative stress in childhood asthma but relatively little information on the oxidant stress in the airways. To determine the extent of ...oxidant/antioxidant imbalance and describe its determinants in the airways of asthmatic children including asthma severity and the genotype of the antioxidant enzymes. One hundred and ten children with mild asthma, 30 children with moderate asthma and 191 healthy controls were included in the study. Exhaled breath condensate (EBC) was collected from all children with EcoScreen®. Levels of malondialdehyde were measured as the indicator of oxidative stress, and of reduced glutathione as the indicator of antioxidant defense. Children were genotyped for the presence of null variants of glutathione S transferase (GST) T1 and GSTM1, and ile105val variant of GSTP1. Risk factors were analyzed with multivariate logistic regression. EBC contained significantly higher levels of malondialdehyde and lower levels of reduced glutathione in asthmatic children compared with healthy controls (P < 0.001 for each), whereas there was no difference between mild and moderate asthmatics. Multivariate logistic regression identified asthma as the only independent factor contributing to oxidative stress. Genotypes of the antioxidant enzymes had no effect on the oxidative burden. Asthma is associated with an extremely powerful oxidative stress not only in the systemic circulation but also in the airways.
Abstract
MicroRNAs (miRNAs) are noncoding RNAs that play an important role in the regulation of inflammation and have not been evaluated in exhaled breath condensates (EBC) of patients with ...esophageal atresia and tracheoesophageal fistula (EA–TEF). It is aimed to evaluate the levels of miRNA-21 and miRNA-24 in EBC of patients with EA–TEF.
Patients who received surgery for EA–TEF (EA) were assessed for age, sex, types of anomaly, surgical treatments, and respiratory problems. A 500–1000 mL of EBC was obtained from each participant with EcoScreen. The levels of miRNA-21 and miRNA-24 in the EBC were analyzed by real-time polymerase chain reaction and compared between the EA group and the control group consisting of healthy children with no history of respiratory problems (n = 17). The levels of miRNAs in relation to respiratory problems and gastroesophageal reflux (GER) were also assessed. A total of 19 patients were enrolled in the EA group with a mean age of 7.8 ± 3.2 years and a male-to-female ratio of 10:9 EA cases had significantly lower levels of miRNA-21 (P < 0.05) compared to that in control group. The miRNA-24 levels did not differ between groups (P > 0.05). EA patients with positive pH testing for GER (n = 6) and fundoplication (n = 6) had higher levels of miRNA-21 than those with normal pH testing and without fundoplication, respectively (n = 13, P < 0.05). The levels of miRNA-21 and miRNA-24 did not differ between patients with and without proton pump inhibitor treatment (P > 0.05).
The lower levels of miRNA-21 in the EBC of EA patients suggest a hyperreactive airway problem, which may be associated with GER and its surgical treatment.
Background
The importance of serum basal tryptase (sBT) levels on patients with venom allergy is highlighted in recent adulthood studies. The aim of this study was to evaluate the sBT levels of ...venom‐allergic children with varying severity of clinical reactions. We also aimed to document the association between sBT levels and severe systemic reactions (SR).
Methods
Serum basal tryptase levels were estimated by UniCAP (Pharmacia & Upjohn, Uppsala, Sweden). Children who suffered from large local reaction (LLR) or SR after insect stings were included along with healthy control subjects without a history of any local or SR after insect stings.
Results
A total of 128 children (55 with SR, 18 with LLR, and 55 age and sex‐matched control subjects) with a median age of 8.9 years (range 3.2–17.4) were enrolled. Severe SR was encountered in 24 (44%) patients with SRs. The median level of sBT in children with SRs (median, interquartile range) 4.2 μg/l (3.6–4.9) was significantly higher than in children with LLRs 3.1 μg/l (2.5–4.0) and healthy control subjects 2.9 μg/l (2.3–3.4) (P < 0.001). Logistic regression analysis revealed sBT ≥ 4.8 μg/l as a significant risk factor for severe SR (5.7 1.5–21.4; P = 0.01) in children with venom allergy.
Conclusions
Our results indicate that sBT levels are associated with a higher risk of severe SR in children with insect venom hypersensitivity. Determination of sBT levels may help clinicians to identify patients under risk of severe SRs and optimal and timely use of therapeutic interventions in children with venom allergy.
Background: Exhaled breath condensate (EBC) is a noninvasive method to obtain samples from fluids lining the respiratory surfaces. Even though various methods and devices are now available, the ...relative efficiency of these methods for recovering airway mediators and characterizing EBC has not been established.
Aim: To compare the volume, pH, lipid mediator, and protein concentrations in EBCs collected by two commonly used commercially available devices, RTubeTM and ECoScreen.
Methods: Exhaled breath condensates were obtained consecutively using the RTubeTM and ECoScreen methods from 30 healthy, nonallergic adults. Samples were immediately placed on dry ice after collection. pH was measured after argon deaeration. Cysteinyl leukotrienes (cys‐LTs) were measured as a representative lipid mediator and eotaxin as the protein mediator by using enzyme‐linked immunosorbent assay.
Results: The mean volume of samples obtained with ECoScreen (1880 ± 116 μl) was significantly higher than that obtained with RTubeTM (1405 ± 82 μl) (P < 0.001). Concentrations of both cys‐LTs 205.4 pg/ml (65.5–472.3) with ECoScreen vs 21.6 (11.87–152.2) with RTubeTM, P < 0.001 and eotaxin 17.0 pg/ml (11.4–22.4) with ECoScreen vs 11.7 (10.5–13.5) with RTubeTM, P = 0.01 were significantly higher in samples collected with ECoScreen than with RTubeTM. There was no significant difference between the pH measurements.
Conclusion: Compared with RTubeTM, collection of exhaled breath by ECoScreen allows larger volumes to be collected and detects protein and lipid mediators with greater sensitivity. These differences in mediator recovery may be due to the differences in the collection temperature.
Background: Endotoxin, with its potential to enhance type 1 immunity, is a significant player in the hygiene hypothesis. The combined effects of the genetic variants of various molecules in the ...endotoxin response pathway on asthma related phenotypes are largely unknown.
Objective: To investigate the effects of the genetic variants of CD14 and TLR4 genes on asthma phenotypes in a large number of asthmatic children.
Methods: 613 asthmatic children were genotyped at the CD14‐C159T, TLR4‐A896G and TLR4‐C1196T loci. IgE, eosinophil numbers and FEV1 were compared in 327 children who were not on any controller medications and were symptom free. Multivariate logistic regression was used to determine the factors associated with total IgE.
Results: Among children with atopic asthma, total IgE levels were significantly different among the three genotypes in the co‐dominant model CC: 435 kU/l (interquartile range: 146–820); CT: 361 (140–710); TT 204 (98–435), P = 0.035. TT genotype was significantly and independently associated with lower IgE levels (OR: 0.5 95%; CI = 0.28–0.90, P = 0.021). Both TLR4‐A896G and TLR4‐C1196T polymorphisms were more frequent in the mild asthma group with atopy (P = 0.032, 0.018, respectively). The combined effects of the genetic variants in CD14 and TLR4 genes did not improve the observed associations.
Conclusion: Our study demonstrates that the CD14‐C159T promoter variant influences total IgE levels and also indicates that the T allele has a more profound effect on total IgE in children with atopic asthma. Polymorphisms in the TLR4 gene may be associated with milder forms of disease in atopic asthmatics in the population studied.
To cite this article: Sackesen C, Birben E, Soyer OU, Sahiner UM, Yavuz TS, Civelek E, Karabulut E, Akdis M, Akdis CA, Kalayci O. The effect of CD14 C159T polymorphism on in vitro IgE synthesis and ...cytokine production by PBMC from children with asthma. Allergy 2011; 66: 48-57. ABSTRACT: Background: Even though the genotype at the promoter region of the CD14 molecule is known to affect the atopic phenotypes, the cellular and molecular basis of this association is largely unknown. Objective: To investigate the effect of lipopolysaccharide (LPS) on IgE production and cytokine profile by peripheral blood mononuclear cells (PBMC) obtained from asthmatic children with the TT and the CC genotypes at position −159 of the CD14 gene. Methods: Peripheral blood mononuclear cells from asthmatic children with alternative genotypes at CD14 C159T locus were stimulated with 2 and 200 ng/ml LPS in vitro. The IgE, IgG and, IgM response was determined by ELISA and Ig έ-germline, IgG, and IgM transcription by real-time PCR. A cluster of cytokines was measured by cytometric bead array. Results: Asthmatic children with the TT genotype but not those with the CC genotype responded with increased IgE synthesis and germline transcription to LPS stimulation. There were no genotype-related differences in IgG and IgM. TT but not the CC genotype was associated with significantly increased interleukin (IL)-4/IL-12 and IL-4/interferon-gamma (IFN-γ) ratios in the culture supernatant. There were no genotype-related differences in IL-1β, IL-7, IL-10, IL-13, IL-17A, granulocyte colony stimulating factor, granulocyte macrophage colony stimulating factor, monocyte chemotactic protein, and tumor necrosis factor alpha. Conclusion: Peripheral blood mononuclear cells from asthmatic children with the TT genotype at position −159 of the CD14 gene make more IgE than those with the CC genotype following LPS stimulation because of increased germline transcription and have an augmented Th2 cytokine profile.
To cite this article: Oflu A, Soyer OU, Tuncer A, Sackesen C, Kalayci O. Eccrine sweat response in children with asthma. Allergy 2010; 65: 645-648. Even though there is a general conviction among ...parents of asthmatic children and pediatricians that asthmatic children sweat more than healthy ones, this has not been formally tested. To determine sweating response and factors affecting this response in children with asthma and compare these findings with healthy children. Eighty-two children with asthma and 51 healthy controls aged 6-18 years were enrolled in the study. Transepidermal water loss (TEWL) was measured on palmar, volar, forehead, and back surfaces before and after exercise and was expressed as the difference between the measurements recorded before and after exercise. Transepidermal water loss measurements (after exercise - resting) on the palmar surface were higher in children with asthma 22.8 g/m² h (15-34.3) compared with healthy children 15.2 g/m² h (6-22.2) (P < 0.001). However, a gender stratified analysis showed that the TEWL measurements were higher on all surfaces only in boys but not in girls. Within the group of asthmatic children, TEWL measurements on the volar surface and back were lower in patients using anti-inflammatory therapy compared with those who were on as needed bronchodilator therapy only. Our results show that asthma is associated with a higher rate of sweating response to exercise in boys, and anti-inflammatory treatment decreases the amount of sweating. The relationship of eccrine sweating with muscarinic receptor response and methacholine hyperresponsiveness remains to be determined.
