IL-4 receptor genetic polymorphisms and asthma in Asian populations.

BACKGROUND: IL-4 receptor alpha chain is crucial for the binding and signaling of IL-4, which mediates isotype switching and IgE production. The gene of IL-4 receptor alpha chain is a candidate gene for asthma and atopy. OBJECTIVES: To determine whether Ile50Val and Q576R polymorphisms of IL-4 receptor alpha chain gene were associated with asthma and higher level of total IgE in Chinese, Malay and Indian populations. METHODS: About 303 physician-diagnosed asthmatic subjects (145 Chinese, 73 Malay, 85 Indian) and 355 unselected blood donors (157 Chinese, 98 Malay, 100 Indian) were recruited. Total serum IgE level was measured by ELISA. Genotypes of Ile50/Val and Q576R were determined by PCR and restriction enzyme length polymorphism (RFLP). RESULTS: Ile50Val heterozygote is less frequent in asthmatics than in controls in Malay population (P=0.007). No difference was found in Chinese and Indian population. Ile50/Ile50 was more prevalent in higher total serum IgE group (IgE>100IU/ml) in Malay. The prevalence of Ile50/R576 haplotype was lower in asthmatics than controls in Chinese (P=0.046); while the prevalence of Ile50/Q576 haplotype was lower in asthmatics than in controls in Malay (P=0.048). The frequencies of the two single nucleotide polymorphisms (SNPs) and haplotypes vary among ethnicities (P<0.05). CONCLUSION: IL-4RA gene polymorphisms and its haplotypes showed ethnic variations. The association between IL-4RA gene polymorphisms, its haplotypes and asthma differed from ethnicities.

Epidemiology of respiratory viruses in patients hospitalized with near-fatal asthma, acute exacerbations of asthma, or chronic obstructive pulmonary disease.

PURPOSE: We compared the prevalence and spectrum of common respiratory viruses among patients with near-fatal asthma, acute exacerbations of asthma, or chronic obstructive pulmonary disease (COPD), and the relation of these findings to acute respiratory symptoms. METHODS: We obtained adequate samples of respiratory secretions from 17 patients hospitalized with near-fatal asthma, 29 with acute asthma, and 14 with COPD. We used a polymerase chain reaction-based method to test for six common respiratory viruses in samples from endotracheal tube aspirates from patients with near-fatal asthma, and from induced sputum specimens from patients with acute asthma or COPD. Respiratory symptoms (runny nose, sore throat, fever, chills, malaise, and cough) were recorded. Quiescent-phase induced sputum specimens were examined from patients who were initially virus positive. RESULTS: Viral nucleic acids were detected in 52% (31/60) of acute-phase specimens and 7% (2/29) of quiescent-phase specimens examined (P <0.001), with similar proportions of virus-positive patients during the acute phase in the three groups: 59% (10/17) of those with near-fatal asthma, 41% (12/29) with acute asthma, and 64% (9/14) with COPD. Picornavirus (47% [n = 8]) and adenovirus (24% [n = 4]) were most commonly identified in near-fatal asthma, whereas influenza virus (36% [n = 5]) predominated in COPD. Virus-positive patients had a significantly increased frequency of runny nose, sore throat, fever, chills, and malaise (odds ratio = 4.1 to 18; P = 0.02 to 0.001). CONCLUSION: Respiratory viruses are associated with hospitalizations for near-fatal asthma, acute asthma, and COPD, with some differences in the spectrum of viruses involved in the different groups of patients. Respiratory viruses are a target for the prevention and perhaps the treatment of these conditions.

Comparison of three methods for respiratory virus detection between induced sputum and nasopharyngeal aspirate specimens in acute asthma.

Viral respiratory tract infections are associated frequently with acute exacerbations of asthma. Nasopharyngeal aspirates and bronchoalveolar lavage specimens are used extensively for detecting viral respiratory tract infections, but not sputum. The aim of the study was to determine the efficiency of viral detection in induced sputum versus nasopharyngeal aspirate obtained during acute exacerbations of asthma, comparing three laboratory methods of viral diagnosis. Paired samples of induced sputum and nasopharyngeal aspirate obtained from 32 adults admitted to hospital with acute asthma were subjected to reverse transcription-polymerase chain reaction (RT-PCR), viral culture, and immunofluorescence assay. The results show that RT-PCR was associated with significantly higher rates of viral detection than culture (P=0.005) or immunofluorescence (P=0.001), without significant differences in the rates of viral detection between induced sputum and nasopharyngeal aspirate. It is concluded that induced sputum specimens are feasible for detection of viral respiratory tract infections by RT-PCR during acute exacerbations of asthma.

The E237G polymorphism of the high-affinity IgE receptor beta chain and asthma.

BACKGROUND: The beta chain of high-affinity IgE receptor (FcepsilonRI beta) has been proposed as a candidate gene for asthma and atopic diseases. OBJECTIVES: To determine the prevalence of the E237G polymorphism of the FcepsilonRI beta gene and to investigate its association with asthma and total IgE levels in 3 Asian populations. METHODS: A total of 291 asthmatic patients (141 Chinese, 68 Malay, and 82 Indian) and 355 asymptomatic blood donors (157 Chinese, 100 Malay, and 98 Indian) were recruited. The E237G genotype was determined by allele-specific polymerase chain reaction. Total serum IgE level was measured by enzyme-linked immunosorbent assay. RESULTS: The G allele was more common in Chinese controls (17.9%) than in Malay (11.5%) (P = .05) and Indian (9.2%) (P = .01) controls. Genotypes with the G allele were more prevalent in asthmatic patients in the Chinese population (odds ratio, 1.97; 95% confidence interval, 1.05-3.77; P = .04). CONCLUSIONS: There were interethnic differences in the frequencies of the G variant among Chinese, Malay, and Indian populations. The E237G polymorphism of FcsRI beta may be a risk factor for asthma in the Chinese population.