CYP3A4 variant alleles in white individuals with low CYP3A4 enzyme activity.

OBJECTIVE: Our objective was to evaluate the presence of CYP3A4 gene variants in white individuals with low CYP3A4 enzyme activity. METHODS: Persons with extremely low enzyme activity, either in vitro or in vivo, were selected in a panel of 97 healthy subjects. Genetic analyses for CYP3A4 variant alleles present in white subjects, including CYP3A4*1B, CYP3A4*2, CYP3A4*4, CYP3A4*5, CYP3A4*6, CYP3A4*8, CYP3A4*11, CYP3A4*12, and CYP3A4*13, were performed on genomic deoxyribonucleic acid from these subjects by amplification-restriction and sequencing. RESULTS: With the exception of CYP3A4*1B, none of the variant alleles analyzed were present in 30 genes from persons with extremely low enzyme activity. CYP3A4*1B was present in the population studied with an allele frequency of 5.5%. Nevertheless, the presence of CYP3A4*1B does not correlate with low enzyme activity, either in vivo or in vitro, in either heterozygosity or homozygosity. CYP3A4*2 was not identified in 290 genes from Spanish persons or in 70 genes from Finnish persons. CONCLUSIONS: Although the genetic component of the interindividual variability of CYP3A4 enzyme activity seems to be high, our findings do not support a key role for the variant alleles analyzed on the majority of white persons with low CYP3A4 activity. This suggests the occurrence of as yet unknown mutations that affect CYP3A4 or other functionally related genes.

Exposure to Aspergillus fumigatus spores induces chemokine expression in mouse macrophages.

Inhalation of fungal spores may cause inflammation and respiratory diseases, such as bronchitis, allergic alveolitis, and asthma. Alveolar macrophages provide the first line of defense in the respiratory tract. To examine the cellular mechanisms involved in Aspergillus fumigatus-induced airway inflammation, mouse macrophage cell line (RAW 264.7) cells were exposed for 2 h or 6 h to graded doses of A. fumigatus spores that were either alive or heat-killed. Furthermore, the ability of the cells to phagocytize the spores was visualized by electron microscopy. Expression of selected cytokines and chemokines was assessed by a real time quantitative PCR method and by enzyme-linked immunoabsorbent assay (ELISA) after exposure. A significant increase in mRNA expression of TNF-alpha, MIP-1alpha, MIP-1beta, and MCP-1 was observed with a maximal induction at 6h after exposure to the highest (1 x 10(7)) concentration of live spores. Similar response was not detected with heat-killed spores in the expression of chemokines and cytokines, even though there were no differences between the phagocytosis of live and heat-killed spores. These results suggest that exposure to live spores of A. fumigatus can modulate the expression of proinflammatory cytokines and chemokines in mouse macrophages and thus influence the development of inflammatory processes in the airways.

Characterization of a common susceptibility locus for asthma-related traits.

Susceptibility to asthma depends on variation at an unknown number of genetic loci. To identify susceptibility genes on chromosome 7p, we adopted a hierarchical genotyping design, leading to the identification of a 133-kilobase risk-conferring segment containing two genes. One of these coded for an orphan G protein-coupled receptor named GPRA (G protein-coupled receptor for asthma susceptibility), which showed distinct distribution of protein isoforms between bronchial biopsies from healthy and asthmatic individuals. In three cohorts from Finland and Canada, single nucleotide polymorphism-tagged haplotypes associated with high serum immunoglobulin E or asthma. The murine ortholog of GPRA was up-regulated in a mouse model of ovalbumin-induced inflammation. Together, these data implicate GPRA in the pathogenesis of atopy and asthma.