[Hypersensitivity pneumonitis in children]

Hypersensitivity pneumonitis (HP) is an interstitial lung disease caused by an immune response to a variety of antigens to which patients have been previously sensitised. It can occur at any age. In children, it is a rare disease, probably under-diagnosed, with an estimated prevalence of 4 per million. The paediatric forms are not really different from those of adults but present some particularities. Avian exposure is by far the most frequent cause of HP, accounting for nearly two-thirds of cases. Although there is no current recommendation for the diagnosis of HP, it is commonly considered that the diagnosis can be made with confidence on the combination of (1) compatible respiratory symptoms, (2) exposure to a known offending antigen, (3) lymphocytic alveolitis, (4) decreased transfer factor for carbon monoxide or hypoxia on exertion and (5) compatible radiologic features. The treatment is based on antigen avoidance that must be complete and definitive. Corticosteroids can be necessary in severe forms. The prognosis of HP in children is better than in adults, with a full clinical and functional recovery in the majority of cases after complete antigenic withdrawal.

Effectiveness of Omalizumab in Severe Allergic Asthma and Nasal Polyposis: A Real-Life Study

BACKGROUND AND OBJECTIVE

Omalizumab is a human anti-IgE antibody approved for the treatment of severe allergic asthma (SAA). However, its effectiveness in SAA associated with chronic rhinosinusitis with nasal polyposis (CRSNP+) is less well documented. Objective: The aim of this study was to evaluate the real-life effectiveness of omalizumab in patients with SAA and CRSNP+ who tolerated and did not tolerate aspirin.

METHODS

We performed a retrospective, observational, multicenter, real-life study of patients with SAA and CRSNP+ treated with omalizumab for 6 months. Asthma outcome parameters (symptoms, number of salbutamol rescues/wk, number of moderate/severe exacerbations, Asthma Control Test score, and lung function), sinonasal outcome parameters (symptoms, number of episodes of acute rhinosinusitis, sinus computed tomography images, nasal polyps endoscopy score), and serum eosinophil levels were analyzed 6 months before and after treatment with omalizumab.

RESULTS

Twenty-four adult patients were included (9 with documented aspirin intolerance). All respiratory parameters were significantly improved by the treatment. In parallel, a significant improvement was observed in sinonasal clinical outcomes and sinus computed tomography images, with no major effect on the nasal polyps endoscopy score. The serum eosinophil count decreased significantly after 6 months of treatment with omalizumab.

CONCLUSION

Treatment of SAA with omalizumab improves the outcome of associated CRSNP+, thus supporting the concept of a "one airway disease".

Skin prick tests and specific IgE in 10-year-old children: Agreement and association with allergic diseases

BACKGROUND

Accurate assessment of atopic sensitization is pivotal to clinical practice and research. Skin prick test (SPT) and specific IgE (sIgE) are often used interchangeably. Some studies have suggested a disagreement between these two methods, and little is known about their association with allergic diseases. The aims of our study were to evaluate agreement between SPT and sIgE, and to compare their association with allergic diseases in 10-year-old children.

METHODS

Skin prick test, sIgE measurements, and assessment of allergic diseases were performed in children aged 10 years in the Protection against Allergy: STUdy in Rural Environments (PASTURE) cohort. The agreement between SPT and sIgE was assessed by Cohen's kappa coefficient with different cutoff values.

RESULTS

Skin prick tests and sIgE were performed in 529 children. The highest agreement (κ=.44) was found with a cutoff value of 3 and 5 mm for SPT, and 3.5 IU/mL for sIgE. The area under the curve (AUC) obtained with SPT was not significantly different from that obtained with sIgE. For asthma and hay fever, SPT (cutoff value at 3 mm) had a significantly higher specificity (P<.0001) than sIgE (cutoff value at 0.35 IU/mL) and the specificity was not different between both tests (P=.1088).

CONCLUSION

Skin prick test and sIgE display moderate agreement, but have a similar AUC for allergic diseases. At the cutoff value of 3 mm for SPT and 0.35 IU/mL for sIgE, SPT has a higher specificity for asthma and hay fever than sIgE without difference for sensitivity.

Severe dyspnea in a patient with neurofibromatosis type 1

Neurofibromatosis type 1 (NF1) is a genetic disease in which pulmonary complications are rare, but severe, especially pulmonary hypertension (PH). The mechanisms underlying the onset of PH in patients with NF1 are unclear and might be multifactorial. In particular, the frequent presence of pulmonary parenchymal lesions makes etiological diagnosis of PH difficult. We describe here the case of a patient with NF1 admitted to our clinic with dyspnea and right heart failure revealing severe pre-capillary PH. Parenchymal lesions were mild and PH was attributed to pulmonary vascular involvement. Clinical and hemodynamic conditions of the patient improved under pulmonary arterial hypertension-specific combination therapy. This case suggests that treatment of PH due to pulmonary vascular involvement in NF1 may be aligned with recommendations for PAH treatment.

A switch in regulatory T cells through farm exposure during immune maturation in childhood

BACKGROUND

Farm exposure protects against development of allergies early in life. At 4.5 years, protection against asthma by farm-milk exposure was partially mediated by regulatory T cells (Tregs). The aim of this study was to investigate the critical time window of the 'asthma-protective' farm effect via Tregs during childhood immune maturation.

METHODS

Tregs were assessed longitudinally at 4.5 and 6 years in 111 children (56 farm and 55 reference children) from the PASTURE/EFRAIM birth cohort (flow cytometry). Peripheral blood mononuclear cells were cultured unstimulated (U), with phorbol 12-myristate 13-acetate/ionomycin (PI) or lipopolysaccharide (LPS), and stained for Tregs (CD4⁺ CD25^high FOXP3^upper20% ). mRNA expression of Treg/Th1/Th2/Th17-associated cell markers was measured ex vivo. Suppressive capacity of Tregs on effector cells and cytokines was assessed. Detailed questionnaires assessing farm exposures and clinical phenotypes from birth until age 6 years were answered by the parents.

RESULTS

Treg percentage before and after stimulation and FOXP3mRNA expression ex vivo decreased from age 4.5 to 6 years (P(U,LPS) < 0.001; P(PI) = 0.051; P(FOXP3) < 0.001). High vs low farm-milk and animal-stable exposure was associated with decreased LPS-stimulated Treg percentage at age 6 years (P(LPS) = 0.045). Elevated LPS-stimulated-Treg percentage at age 6 was associated with increased risk of asthma (aOR = 11.29, CI: 0.96-132.28, P = 0.053). Tregs from asthmatics vs nonasthmatics suppressed IFN-γ (P = 0.015) and IL-9 (P = 0.023) less efficiently. mRNA expression of Th1/Th2/Th17-associated cell markers decreased between 4.5 and 6 years (P < 0.001).

CONCLUSIONS

Tregs at the age of 6 years were decreased with farm exposure and increased within asthmatics, opposite to age 4.5 years. This immunological switch defines a critical 'time window' for Treg-mediated asthma protection via environmental exposure before age 6 years.

Farm exposures are associated with lower percentage of circulating myeloid dendritic cell subtype 2 at age 6

BACKGROUND

Early life farm exposures have been shown to decrease the risk of allergic diseases. Dendritic cells (DCs) may mediate asthma-protective effect of farm exposures as they play an important role in the development of immunity and tolerance. Our aim was to investigate whether the numbers and phenotypes of circulating DCs at age 6 are associated with farming, asthma, and atopy in a selected sample of French and Finnish children from the PASTURE study.

METHODS

We studied 82 farm and 86 nonfarm children with and without asthma. Using flow cytometry, BDCA1+ CD11c+ myeloid DC1s (mDC1), BDCA3+(high) mDC2s and BDCA2+ plasmacytoid DCs (pDCs) were identified and expressions of CD86, immunoglobulin-like transcript 3 (ILT3) and ILT4 were analyzed. Questionnaires were used to assess prenatal and lifetime patterns of farm exposures and to define asthma. Atopic sensitization was defined by specific IgE measurements.

RESULTS

The percentage of mDC2 cells was lower in farm children (0.033 ± 0.001) than in nonfarm children (0.042 ± 0.001; P = 0.008). Similar associations were found between mDC2 percentage and prenatal (P = 0.02) and lifetime exposure to farm milk (P = 0.03) and stables (P = 0.003), but these associations were not independent from farming. Asthma was positively associated with ILT4 + mDCs (P = 0.04) and negatively with CD86 + pDCs (P = 0.048) but only in nonfarm children.

CONCLUSIONS

Inverse association between farm exposure and mDC2 percentage suggest that this DC subset may play a role in farm-related immunoregulation.

Serum vitamin E concentrations at 1 year and risk of atopy, atopic dermatitis, wheezing, and asthma in childhood: the PASTURE study

BACKGROUND

Prospective studies investigating the role of serum vitamin E concentrations during early life in the development of childhood allergies and asthma are limited.

OBJECTIVE

To study the associations between serum vitamin E concentrations at first year of life and longitudinal development of atopy, atopic dermatitis, wheeze, and asthma up to 6 years of age.

METHODS

The setting was the PASTURE study, a multicenter prospective birth cohort study in five European rural settings. Children of 1133 mothers recruited during pregnancy were followed from birth with measurement of serum vitamin E levels at year 1 and repeated assessments of serum immunoglobulin E antibodies (year 1, 4.5, 6), atopic dermatitis, wheezing symptoms, and asthma (year 1, 1.5, 2, 3, 4, 5, 6).

RESULTS

At 6 years of age, 66% and 82% of the original 1133 subjects underwent blood test for IgE and answered the questionnaire, respectively. We did not observe any statistically significant associations between serum vitamin E concentrations at year 1 and the endpoints, but borderline inverse associations between alpha tocopherol and wheezing without cold (OR 0.45, 95% CI 0.19-1.09) and any wheezing symptom (OR 0.52, 95% CI 0.27-1.02).

CONCLUSIONS

Serum vitamin E concentrations at year 1 were not associated with allergies or asthma by 6 years of age. While further prospective studies with repeated assessments of vitamin E during early life may clarify its putative role in the development of the diseases, it is also possible that the antioxidant hypothesis in the development of allergies and asthma does not hold.

Farm exposure and time trends in early childhood may influence DNA methylation in genes related to asthma and allergy

BACKGROUND

Genetic susceptibility and environmental influences are important contributors to the development of asthma and atopic diseases. Epigenetic mechanisms may facilitate gene by environment interactions in these diseases.

METHODS

We studied the rural birth cohort PASTURE (Protection against allergy: study in rural environments) to investigate (a) whether epigenetic patterns in asthma candidate genes are influenced by farm exposure in general, (b) change over the first years of life, and (c) whether these changes may contribute to the development of asthma. DNA was extracted from cord blood and whole blood collected at the age of 4.5 years in 46 samples per time point. DNA methylation in 23 regions in ten candidate genes (ORMDL1, ORMDL2, ORMDL3, CHI3L1, RAD50, IL13, IL4, STAT6, FOXP3, and RUNX3) was assessed by pyrosequencing, and differences between strata were analyzed by nonparametric Wilcoxon-Mann-Whitney tests.

RESULTS

In cord blood, regions in ORMDL1 and STAT6 were hypomethylated in DNA from farmers' as compared to nonfarmers' children, while regions in RAD50 and IL13 were hypermethylated (lowest P-value (STAT6) = 0.001). Changes in methylation over time occurred in 15 gene regions (lowest P-value (IL13) = 1.57*10(-8)). Interestingly, these differences clustered in the genes highly associated with asthma (ORMDL family) and IgE regulation (RAD50, IL13, and IL4), but not in the T-regulatory genes (FOXP3, RUNX3).

CONCLUSIONS

In this first pilot study, DNA methylation patterns change significantly in early childhood in specific asthma- and allergy-related genes in peripheral blood cells, and early exposure to farm environment seems to influence methylation patterns in distinct genes.