Sequence variants in the FcepsilonRI alpha chain gene.

There is a relationship between IgE levels and expression of high-affinity IgE receptors (FcepsilonRI). Because the alpha chain is the only portion of the receptor that binds directly to IgE, we reasoned that sequence variants in the FcepsilonRI alpha gene may exist that alter these binding events. We screened all of the exons and the promoter region of the FcepsilonRI alpha chain gene with genomic DNA from 389 asthmatic and 341 normal control subjects for mutations by using single-stranded conformational polymorphism analysis. No nonsynonomous single nucleotide polymorphisms (SNPs) were identified in the coding region. Three SNPs were found in the promoter region: an A/C transversion at -770 from the translation start site; a G/A transition at -664; and a T/C transition at -335. No differences in allele frequencies were detected between asthmatic subjects and controls. Homozygosity for the C variant at locus -335 was more common in Caucasian asthmatic patients with IgE levels in the lower quartile than in the upper quartile (P = 0.032). An analysis of highly polymorphic SNPs indicated that this association is unlikely to be due to population substructure. We conclude that homozygosity for the C allele of FcepsilonRI alpha chain variant is associated with lower IgE levels

Enhanced Goblet Cell Hyperplasia in HDC Knockout Mice with Allergic Airway Inflammation

Background: Histamine is known to have immunoregulatory roles in allergic reactions through histamine receptor 1 (H1R), H2R, H3R and H4R. However, its role in goblet cell hyperplasia in the airways of asthma patients is yet to be clarified. Objective: This study was designed to examine the role of histamine in goblet cell hyperplasia using histamine-deficient mice (Hdc-/- mice) with allergic airway inflammation. Methods: Wild-type and Hdc-/- C57BL/6 mice were sensitized with ovalbumin (OVA). After a 2-week exposure to OVA, goblet cell hyperplasia was evaluated. Cell differentials and cytokines in BALF were analyzed. The mRNA levels of MUC5AC and Gob-5 gene were determined quantitatively. Results: The number of eosinophils in BALF increased in both the sensitized wild-type mice and Hdc-/- mice with OVA inhalation. In addition, the numbers of alveolar macrophages and lymphocytes in BALF increased significantly in the sensitized Hdc-/- mice with OVA inhalation compared to the wild-type mice under the same conditions. The concentrations of Interleukin-4 (IL-4), IL-5, IL-13, Interferon-γ (IFN-γ), tumor necrosis factor-α (TNF-α) and IL-2 in the BALF all increased significantly in both groups compared to those exposed to saline. In particular, the concentration of TNF-α in the Hdc-/- mice exposed to OVA was significantly higher than that in the wild-type mice under the same conditions. The mRNA levels of Gob-5 and MUC5AC, and the ratio of the goblet cells in the airway epithelium significantly increased in Hdc-/- mice exposed to OVA compared to wild-type mice. Conclusions: These results suggested that histamine may play a regulatory role in goblet cell hyperplasia in allergic airway inflammation

Cloning and functional analysis of the mouse 5-lipoxygenase promoter.

5-lipoxygenase (ALOX5), an enzyme essential for the formation of all leukotrienes, is highly regulated at multiple levels, including gene transcription. The human ALOX5 promoter sequence has been cloned and is well characterized. Several important cis-acting elements have been identified including a G+C-rich sequence approximately 145-179 base pairs (bp) upstream from the ATG start codon. This region contains consensus-binding sites for the transcription factor serum protein 1, a zinc-finger transcription factor (SP1) and early growth-response protein 1, a zinc-finger transcription factor (EGR-1) and is unique in that functionally significant polymorphisms alter these sequences. To further understand the significance of these polymorphisms and other regulatory sequences in the promoter we cloned approximately 2,000 bp of the mouse promoter sequence from a 129/SvJ BAC library for direct comparison with the human gene. Like the human promoter, the mouse Alox5 promoter lacks a TATA box and has multiple start sites. The first 292 bp immediately upstream of the translational start site function as a core promoter that is capable of mediating high basal transcription in RAW cells but not 3T3 cells. There are vast differences in the distribution of consensus cis elements between human and mouse genes; however, three areas of strong homology exist and they contain consensus-binding sites for the SP1, GATA, GGAGA, and ETS family of transcription factors. We show that Sp1/Sp3 is essential for constitutive promoter-reporter activity

Transforming growth factor-beta1 promoter polymorphism C-509T is associated with asthma.

Transforming growth factor-beta1 (TGF-beta1) is increased in the lungs of individuals with asthma and may modulate airway inflammation and remodeling. Some genetic studies have found that a C-to-T single-nucleotide polymorphism (C-509T) in the TGF-beta1 gene promoter may be associated with altered gene expression and asthma phenotype. To build on these data, we performed a case-control association study at this locus involving 527 subjects with asthma and 170 control subjects without asthma. All individuals were white. Genotyping at 49 unlinked polymorphisms indicated that a subset of case subjects and all control subjects were well matched and without evidence of population stratification. Logistic regression was used to model the effects of age, sex, and genotype on case-control status. The diagnosis of asthma was positively associated with the T allele and TT genotype under a codominant model (odds ratio, 2.98; 95% confidence interval, 1.45 to 6.25; p = 0.003). Total serum IgE, eosinophil count, and FEV1% predicted levels were not associated with this polymorphism. Furthermore, we show that the C-509T polymorphism alters TGF-beta1 promoter-reporter activity and promoter interactions with the transcription factor Yin Yang 1. We conclude that the T allele of C-509T is associated with the diagnosis of asthma and may enhance TGF-beta1 gene transcription