Helicobacter pylori in early childhood and asthma in adolescence

Objective

An inverse effect of Helicobacter pylori (H. pylori) on the occurrence of asthma is debated and early acquisition of H. pylori may be important. We analyzed sera from 197 children from Environment and Childhood Asthma (ECA) study in Oslo for Helicobacter pylori (H. pylori) at 2 and 10 years, and symptoms and signs of asthma at 16 years of age.

Results

While 16.4% of children who were H. pylori negative at 2 and 10 years had current asthma at 16 years, none of the 12 children who were H. pylori positive at 2 years of age had asthma at the age of 16 years, regardless of H. pylori status at 10 years. This trend for less current asthma in children who were H. pylori positive at 2 years compared to persistent or transient negative status at 10 years was not statistically significant, probably due to low number of H. pylori positive children at 2 years of age. Acquisition of H. pylori in school age did not appear to influence the risk of current asthma. Much larger prospective studies are probably required to document whether or not early H. pylori infection may be involved in the risk of asthma development in later childhood.

HLA Dr-Dq haplotypes and the TNFA-308 polymorphism: associations with asthma and allergy

BACKGROUND

The HLA (human leukocyte antigen) class II genes DQB1 and DRB1 and the Tumor Necrosis Factor alpha gene (TNFA) within the HLA complex (chromosome 6p21) have been associated with asthma and allergy. Due to the strong linkage disequilibrium characterizing this complex and the multiple asthma/allergy expressions, we aimed to determine which of these genes were primarily involved in specific asthma/allergy traits.

METHODS

The DRB1-DQB1 alleles and TNFA-308 polymorphism were genotyped in 959 children from the Environment and Childhood Asthma study and analyzed for possible associations with allergic and non-allergic asthma (with/without at least one positive skin prick test for allergens) and specific allergic sensitization, as well as bronchial hyperresponsiveness and total IgE, using both allele and extended haplotype analyses.

RESULTS

Different genes within the HLA complex were associated with separate asthma and allergy traits. Nonallergic asthma was associated with both the TNFA-308A allele [Odds ratio (OR) 1.7 (1.3-2.3)] and DRB1 03 allele [OR 1.6(1-2.6)], but extended DRB1 03-TNFA-308 haplotype analysis suggested that the DRB1-DQB1 association was secondary to linkage disequilibrium with the TNFA-308 polymorphism. Allergies were associated with HLA class II alleles only; birch sensitization with DQB1 0603-DRB1 13 [OR 2.3 (1.4-4.0)] and mugwort sensitization with DQB1 0609-DRB1 13 [OR 7.1 (1.9-27.0)] and DQB1 0501-DRB1 01 [OR 2.0 (1.0-4.0)].

CONCLUSIONS

Our data suggests that asthma is not associated with DRB1 or DQB1 but rather TNFA or a gene(s) in linkage disequilibrium, while sensitization to specific allergens is associated with particular alleles at the DQ and/or DR loci. A novel association between DQB1 0603-DRB1 13 and birch allergy is identified.

Eosinophil cationic protein (ECP) polymorphisms and association with asthma, s-ECP levels and related phenotypes

BACKGROUND

Eosinophil cationic protein (ECP) is a potent cytotoxic secretory protein with bactericidal and antiviral properties. ECP is released by activated eosinophils and regarded as a marker of eosinophilic inflammation. High levels of ECP have been reported in cases of active asthma and other allergic diseases. This study aimed to assess whether three single-nucleotide polymorphisms (SNPs) in the ECP gene (RNASE3) on chromosome 14 q24-q31 or their haplotypes are associated with asthma, allergy, or related phenotypes.

METHODS

The three SNPs -38CA, +371CG and +499CG in RNASE3 and their haplotypes were analyzed for associations with asthma, serum-ECP (s-ECP) levels, allergic sensitization (positive skin-prick test to common allergens), bronchial hyperresponsiveness (BHR) assessed by methacholine inhalation, and serum-IgE (s-IgE) levels in 177 families from Norway and the Netherlands identified through siblings with asthma.

RESULTS

Transmission disequilibrium test (TDT) demonstrated significant associations between the A-G-G haplotype and asthma as well as the specific phenotypes allergic asthma (but not non-allergic asthma), high s-ECP, high s-IgE and BHR, while the C-G-G haplotype was associated with reduced occurrence of these traits. In addition, the -38A allele was associated with high s-ECP levels and allergic asthma.

CONCLUSION

The present study suggests that the A-G-G haplotype in the RNASE3 gene influences the development of asthma, in particular, an allergic form of asthma. Furthermore, as the -38CA SNP lies in close vicinity of known intron-regulatory sites, results of SNP analysis suggest that the detected association is possibly linked to a genetic transcriptional control of s-ECP levels.