Association of polymorphisms in the beta2-adrenoreceptor gene with higher levels of parasitic infection

Weighted single-step genome-wide association study and functional enrichment analyses for gastrointestinal nematode resistance traits in Santa Ines sheep

This study aimed to identify genomic regions, pathways, and putative candidate genes associated with resistance to gastrointestinal nematode in Santa Ines sheep. The phenotypic information comprised 5529 records from 1703 naturally infected animals. After genomic data quality control, 37,511 SNPs from 589 animals were available. The weighted single-step approach for genome-wide association study was performed to estimate the SNP effects and variances accounted by 10-SNP sliding windows. Confirming the polygenic nature of the studied traits, 20, 22, 21, and 19 genomic windows that explained more than 0.5% of the additive genetic variance were identified for fecal egg counts (FEC), Famacha© (FAM), packed cell volume (PCV), and total plasma protein (TPP), respectively. A total of 81, 122, 106, and 101 protein-coding genes were found in windows associated with FEC, FAM, PCV, and TPP, respectively. Several protein-coding genes related to the immune system and inflammatory response functions were identified within those genomic regions, such as ADCY9, ADRB2, BRAF, CADM1, CCL20, CD70, CREBBP, FNBP1, HTR4, IL16, IL22, IL26, MAPK8, NDFIP1, NLRC3, PAK5, PLCB1, PLCB4, ROCK1, TEK, TNFRSF12A, and VAV1. Functional enrichment analysis by DAVID tool also revealed many significant (P < 0.05) pathways and Gene Ontology terms that could be related to resistance to gastrointestinal nematode in Santa Ines sheep, such as chemokine signaling pathway (oas04062), cAMP signaling pathway (oas04024), cGMP-PKG signaling pathway (Oas04022), platelet activation (Oas04611), Rap1 signaling pathway (oas04015), and oxidoreductase activity, acting on paired donors, with incorporation or reduction of molecular oxygen (GO:0016705). These results contribute to improving the knowledge of the genetic architecture of resistance to gastrointestinal nematode in Santa Ines sheep.

PTTG1IP and MAML3, novel genomewide association study genes for severity of hyperresponsiveness in adult asthma

BACKGROUND

The severity of bronchial hyperresponsiveness (BHR) is a fundamental feature of asthma. The severity of BHR varies between asthmatics and is associated with lack of asthma control. The mechanisms underlying this trait are still unclear. This study aimed to identify genes associated with BHR severity, using a genomewide association study (GWAS) on the slope of BHR in adult asthmatics.

METHODS

We performed a GWAS on BHR severity in adult asthmatics from the Dutch Asthma GWAS cohort (n = 650), adjusting for smoking and inhaled corticosteroid use, and verified results in three other cohorts. Furthermore, we performed eQTL and co-expression analyses in lung tissue.

RESULTS

In the discovery cohort, one genomewide significant hit located in phosphodiesterase 4D, cAMP-specif (PDE4D) and 26 SNPs with P-values < 1*10^-5 were found. None of our findings replicated in adult and childhood replication cohorts jointly. In adult cohorts separately, rs1344110 in pituitary tumour-transforming 1 interacting protein (PTTG1IP) and rs345983 in Mastermind-like 3 (MAML3) replicated nominally; minor alleles of rs345983 and rs1344110 were associated with less severe BHR and higher lung tissue gene expression. PTTG1IP showed significant co-expression with pituitary tumour-transforming 1, the binding factor of PTTG1lP, and with vimentin and E-cadherin1. MAML3 co-expressed significantly with Mastermind-like 2 (MAML2), both involved in Notch signalling.

CONCLUSIONS

PTTG1IP and MAML3 are associated with BHR severity in adult asthma. The relevance of these genes is supported by the eQTL analyses and co-expression of PTTG1lP with vimentin and E-cadherin1, and MAML3 with MAML2.

Genetic Variants in CHIA and CHI3L1 Are Associated with the IgE Response to the Ascaris Resistance Marker ABA-1 and the Birch Pollen Allergen Bet v 1

Helminth infections and allergic diseases are associated with IgE hyperresponsiveness but the genetics of this phenotype remain to be defined. Susceptibility to Ascaris lumbricoides infection and antibody levels to this helminth are associated with polymorphisms in locus 13q33-34. We aimed to explore this and other genomic regions to identify genetic variants associated with the IgE responsiveness in humans. Forty-eight subjects from Cartagena, Colombia, with extreme values of specific IgE to Ascaris and ABA-1, a resistance marker of this nematode, were selected for targeted resequencing. Burden analyses were done comparing extreme groups for IgE values. One-hundred one SNPs were genotyped in 1258 individuals of two well-characterized populations from Colombia and Sweden. Two low-frequency coding variants in the gene encoding the Acidic Mammalian Chitinase (CHIA rs79500525, rs139812869, tagged by rs10494133) were found enriched in high IgE responders to ABA-1 and confirmed by genetic association analyses. The SNP rs4950928 in the Chitinase 3 Like 1 gene (CHI3L1) was associated with high IgE to ABA-1 in Colombians and with high IgE to Bet v 1 in the Swedish population. CHIA rs10494133 and ABDH13 rs3783118 were associated with IgE responses to Ascaris. SNPs in the Tumor Necrosis Factor Superfamily Member 13b gene (TNFSF13B) encoding the cytokine B cell activating Factor were associated with high levels of total IgE in both populations. This is the first report on the association between low-frequency and common variants in the chitinases-related genes CHIA and CHI3L1 with the intensity of specific IgE to ABA-1 in a population naturally exposed to Ascaris and with Bet v 1 in a Swedish population. Our results add new information about the genetic influences of human IgE responsiveness; since the genes encode for enzymes involved in the immune response to parasitic infections, they could be helpful for understanding helminth immunity and allergic responses. We also confirmed that TNFSF13B has an important and conserved role in the regulation of total IgE levels, which supports potential evolutionary links between helminth immunity and allergic response.

Adrenergic regulation of innate immunity: a review

The sympathetic nervous system has a major role in the brain-immune cross-talk, but few information exist on the sympathoadrenergic regulation of innate immune system. The aim of this review is to summarize available knowledge regarding the sympathetic modulation of the innate immune response, providing a rational background for the possible repurposing of adrenergic drugs as immunomodulating agents. The cells of immune system express adrenoceptors (AR), which represent the target for noradrenaline and adrenaline. In human neutrophils, adrenaline and noradrenaline inhibit migration, CD11b/CD18 expression, and oxidative metabolism, possibly through β-AR, although the role of α₁- and α₂-AR requires further investigation. Natural Killer express β-AR, which are usually inhibitory. Monocytes express β-AR and their activation is usually antiinflammatory. On murine Dentritic cells (DC), β-AR mediate sympathetic influence on DC-T cells interactions. In human DC β₂-AR may affect Th1/2 differentiation of CD4+ T cells. In microglia and in astrocytes, β₂-AR dysregulation may contribute to neuroinflammation in autoimmune and neurodegenerative disease. In conclusion, extensive evidence supports a critical role for adrenergic mechanisms in the regulation of innate immunity, in peripheral tissues as well as in the CNS. Sympathoadrenergic pathways in the innate immune system may represent novel antiinflammatory and immunomodulating targets with significant therapeutic potential.

Host genetics and parasitic infections

Parasites still impose a high death and disability burden on human populations, and are therefore likely to act as selective factors for genetic adaptations. Genetic epidemiological investigation of parasitic diseases is aimed at disentangling the mechanisms underlying immunity and pathogenesis by looking for associations or linkages between loci and susceptibility phenotypes. Until recently, most studies used a candidate gene approach and were relatively underpowered, with few attempts at replicating findings in different populations. However, in the last 5 years, genome-wide and/or multicentre studies have been conducted for severe malaria, visceral leishmaniasis, and cardiac Chagas disease, providing some novel important insights. Furthermore, studies of helminth infections have repeatedly shown the involvement of common loci in regulating susceptibility to distinct diseases such as schistosomiasis, ascariasis, trichuriasis, and onchocherciasis. As more studies are conducted, evidence is increasing that at least some of the identified susceptibility loci are shared not only among parasitic diseases but also with immunological disorders such as allergy or autoimmune disease, suggesting that parasites may have played a role in driving the evolution of the immune system.

What the Genetic Background of Individuals with Asthma and Obesity Can Reveal: Is β2-Adrenergic Receptor Gene Polymorphism Important?

The goal of this review was to evaluate the association of β2-adrenergic receptor (ADRB2) gene polymorphisms with asthma and obesity. Asthma is the most common pediatric inflammatory disorder. The prevalence, severity, and hospitalization index for asthma have increased markedly in the last several decades. Interestingly, asthma is often diagnosed along with obesity. Genetic factors are essential for both conditions, and some of the candidate pleiotropic genes thought to be involved in the development of these diseases are ADRB2, vitamin D receptor (VDR), leptin (LEP), protein kinase C alpha (PRKCA), and tumor necrosis factor alpha (TNFα). The ADRB2 has been studied in multiple populations and more than 80 polymorphisms, mainly single-nucleotide polymorphisms, have been identified. For nonsynonymous Arg16Gly, Gln27Glu, and Thr164Ile, functional effects have been shown. In vivo, these polymorphisms have been evaluated to determine their association with both obesity and asthma, but the results are inconsistent and depend on the population studied or how the disease was defined. Currently, there are only few reports describing the genetic background for the comorbidity of asthma and obesity.

High malnutrition rate in Venezuelan Yanomami compared to Warao Amerindians and Creoles: significant associations with intestinal parasites and anemia

BACKGROUND

Children in rural areas experience the interrelated problems of poor growth, anemia and parasitic infections. We investigated the prevalence of and associations between intestinal helminth and protozoan infections, malnutrition and anemia in school-age Venezuelan children.

METHODS

This cross-sectional study was conducted in 390 children aged 4-16 years from three rural areas of Venezuela: the Amazon Region, Orinoco Delta and Carabobo State. Stool samples were collected for direct parasitic examinations. Anthropometric indicators of chronic (height-for-age Z score) and acute (weight-for-height and Body Mass Index (BMI)-for-age Z score in respectively children under 5 years of age and children aged 5 years and above) malnutrition were calculated. Multivariate linear and logistic regression models were built to determine factors associated with nutritional status and polyparasitism.

RESULTS

Hookworm and Strongyloides stercoralis prevalences were highest in children from the Amazon rainforest (respectively 72% and 18%) while children from the Orinoco Delta and Carabobo State showed higher rates of Ascaris lumbricoides (respectively 28% and 37%) and Trichuris trichiura (40% in both regions). The prevalence of Giardia lamblia infection was not significantly different between regions (average: 18%). Anemia prevalence was highest in the Amazon Region (24%). Hemoglobin levels were significantly decreased in children with a hookworm infection. Malnutrition was present in respectively 84%, 30% and 13% of children from the Amazon Region, Orinoco Delta and Carabobo State. In multivariate analysis including all regions, G. lamblia and helminth infections were significantly and negatively associated with respectively height-for-age and weight-for-height/BMI-for-age Z scores. Furthermore, hemoglobin levels were positively associated with the height-for-age Z score (0.11, 95% CI 0.02 - 0.20).

CONCLUSIONS

In rural populations in Venezuela helminthiasis and giardiasis were associated with acute and chronic nutritional status respectively. These data highlight the need for an integrated approach to control transmission of parasites and improve the health status of rural Venezuelan children.

Patterns and processes in parasite co-infection

Co-infection of individual hosts by multiple parasite species is a pattern that is very commonly observed in natural populations. Understanding the processes that generate these patterns poses a challenge. For example, it is difficult to discern the relative roles of exposure and susceptibility in generating the mixture and density of parasites within hosts. Yet discern them we must, if we are to design and deliver successful medical interventions for co-infected populations. Here, we synthesise an emergent understanding of how processes operate and interact to generate patterns of co-infection. We consider within-host communities (or infracommunities) generally, that is including not only classical parasites but also the microbiota that are so abundant on mucosal surfaces and which are increasingly understood to be so influential on host biology. We focus on communities that include a helminth, but we expect similar inferences to pertain to other taxa. We suggest that, thanks to recent research at both the within-host (e.g. immunological) and between-host (e.g. epidemiological) scales, researchers are poised to reveal the processes that generate the observed distribution of parasite communities among hosts. Progress will be facilitated by using new technologies as well as statistical and experimental tools to test competing hypotheses about processes that might generate patterns in co-infection data. By understanding the multiple interactions that underlie patterns of co-infection, we will be able to understand and intelligently predict how a suite of co-infections (and thus the host that bears them) will together respond to medical interventions as well as other environmental changes. The challenge for us all is to become scholars of co-infections.

The role of Intelectin-2 in resistance toAscaris suumlung larval burdens in susceptible and resistant mouse strains

The underlying mechanism of predisposition toAscarisinfection is not yet understood but host genetics are thought to play a fundamental role. We investigated the association between the Intelectin-2 gene and resistance in F2mice derived from mouse strains known to be susceptible and resistant to infection.Ascarislarvae were isolated from murine lungs and the number of copies of the Intelectin-2 gene was determined in F2mice. Intelectin-2 gene copy number was not significantly linked to larval burden. In a pilot experiment, the response to infection in parental mice of both sexes was observed in order to address the suitablity of female F2mice. No overall significant sex effect was detected. However, a divergence in resistance/susceptibility status was observed between male and, female hybrid offspring. The responsiveness toAscarisin mice is likely to be controlled by multiple genes and, despite a unique absence from the susceptible C57BL/6j strain, the Intelectin-2 gene does not play a significant role in resistance. The observed intra-strain variation in larval burden requires further investigation but we hypothesize that it stems from social/dominance hierarchies created by the presence of female mice and possibly subsequent hormonal perturbations that modify the intensity of the immune response.

Investigating the underlying mechanism of resistance to Ascaris infection

The generative mechanism(s) of predisposition to Ascaris infection are currently unknown. While many factors play a role in interindividual infection intensity, much focus has been placed on the host's immunological response to infection and the underlying genetics. The present review describes the research conducted that has examined various immunological parameters and genetic factors that may play a role in resistance to ascariasis. We also discuss the contribution that animal models have made to our understanding of resistance to the parasitic roundworm and their role in possible future work.

Probable role of Beta 2-adrenergic receptor gene haplotype in toluene diisocyanate-induced asthma

PURPOSE

A genetic polymorphism of the beta 2-adrenergic receptor is a major factor associated with the asthmatic phenotype. The association of this polymorphism with toluene diisocyanate (TDI)-induced asthma has not been investigated. We examined 103 TDI-induced asthma patients (TDI-OA), 60 asymptomatic exposed controls (AEC), and 263 unexposed healthy controls (NC) in order to identify beta 2-adrenergic receptor gene (ADRB2) polymorphisms and the possible association with TDI-induced asthma.

METHODS

Single nucleotide polymorphisms (SNPs) of ADRB2 were genotyped by direct sequencing. Serum-specific IgE and IgG levels were measured using an enzyme-linked immunosorbent assay. Phenotypes and clinical patient parameters were compared.

RESULTS

SNPs were identified (-47 T>C, -20 T>C, Arg16Gly A>G, Gln27Glu C>G, Leu134Leu G>A, Arg175Arg C>A) during ADRB2 screening (from -231 to 793 bp). No significant differences in allelic and genotypic frequencies were noted for any of the six ADRB2 SNPs. The Arg16Gly A>G, Leu134Leu G>A, and Arg175Arg C>A SNPs and haplotype 1 [TTACGC] were significantly associated with specific IgE antibodies to the TDI-human serum albumin (HSA) conjugate in TDI-exposed subjects (P<0.05). Exposed workers with the ADRB2 ht1/ht1 homozygote had a significantly higher TDI-HSA conjugate-specific IgE sensitization rate than did those with the null ht1 haplotype (odds ratio, 15.40; 95% confidence interval, 1.81-131.06).

CONCLUSIONS

ADRB2 polymorphisms may affect IgE-specific sensitization to TDI-HSA conjugate in TDI-exposed workers.

Increased parasite resistance and recurrent airway obstruction in horses of a high-prevalence family

BACKGROUND

Equine recurrent airway obstruction (RAO) shares many characteristics with human asthma. In humans, an inverse relationship between susceptibility to asthma and resistance to parasites is suspected.

HYPOTHESIS/OBJECTIVES

Members of a high-incidence RAO half-sibling family (F) shed fewer strongylid eggs compared with RAO-unaffected pasture mates (PM) and that RAO-affected horses shed fewer eggs than RAO-unaffected half-siblings.

ANIMALS

Seventy-three F and 73 unrelated, age matched PM.

METHODS

Cases and controls kept under the same management and deworming regime were examined. Each individual was classified as RAO affected or RAO unaffected and fecal samples were collected before and 1-3 weeks and 3 months after deworming. Samples were analyzed by combined sedimentation-flotation and modified McMaster methods and classified into 3 categories of 0 eggs per gram of feces (EpG), 1-100 EpG, and > 100 EpG, respectively.

RESULTS

PM compared with RAO-affected F had a 16.7 (95% confidence interval [CI]: 2.0-136.3) times higher risk for shedding > 100 EpG compared with 0 EpG and a 5.3 (95% CI: 1.0-27.4) times higher risk for shedding > 100 EpG compared with 0 EpG. There was no significant effect when RAO-unaffected F were compared with their PM. RAO-unaffected compared with RAO-affected offspring had a 5.8 (95% CI: 0.0-1.0) times higher risk for shedding 1-100 EpG. Age, sex, breed, and sharing pastures with other species had no significant confounding effects.

CONCLUSION AND CLINICAL IMPORTANCE

RAO is associated with resistance against strongylid parasites in a high-prevalence family.

Association between total immunoglobulin E and antibody responses to naturally acquired Ascaris lumbricoides infection and polymorphisms of immune system-related LIG4, TNFSF13B and IRS2 genes

The 13q33-34 region harbours a susceptibility locus to Ascaris lumbricoides, although the underlying genes are unknown. Immunoglobulin (Ig)E and IgG confer protective immunity and here we sought to investigate in an endemic population whether LIG4, TNFSF13B and IRS2 genes influence IgE and IgG levels against Ascaris and the ABA-1 allergen as a putative resistance marker. Mite-allergic asthmatic patients were analysed for potential relationships between Ascaris predisposition and allergy. One thousand and sixty-four subjects from Cartagena, Colombia, were included. Single nucleotide polymorphisms (SNPs) were genotyped using TaqMan assays. Antibody levels were measured by enzyme-linked immunosorbent assay. Linear and logistic regressions were used to model effects of genotypes on antibody levels. The GG genotype of LIG4 (rs1805388) was associated with higher IgE levels to Ascaris compared with other genotypes. TNFSF13B (rs10508198) was associated positively with IgG levels against Ascaris extract and IgE levels against ABA-1. In asthmatics, IRS2 (rs2289046) was associated with high total IgE levels. Associations held up after correction by population stratification using a set of 52 ancestry markers, age, sex and disease status. There was no association with asthma or mite sensitization. In a tropical population, LIG4 and TNFSF13B polymorphisms are associated with specific IgE and IgG to Ascaris, supporting previous linkage studies implicating the 13q33 region. Our results suggest that genes protecting against parasite infections can be different to those predisposing to asthma and atopy.

Diverse evolutionary histories for beta-adrenoreceptor genes in humans

In humans, three genes--ADRB1, ADRB2 and ADRB3--encode beta-adrenoreceptors (ADRB); these molecules mediate the action of catecholamines in multiple tissues and play pivotal roles in cardiovascular, respiratory, metabolic, and immunological functions. Genetic variants in ADRB genes have been associated with widespread diseases and conditions, but inconsistent results have often been obtained. Here, we addressed the recent evolutionary history of ADRB genes in human populations. Although ADRB1 is neutrally evolving, most tests rejected neutral evolution for ADRB2 in European, African, and Asian population samples. Analysis of inferred haplotypes for ADRB2 revealed three major clades with a coalescence time of 1-1.5 million years, suggesting that the gene is either subjected to balancing selection or undergoing a selective sweep. Haplotype analysis also revealed ethnicity-specific differences. Additionally, we observed significant deviations from Hardy-Weinberg equilibrium (HWE) for ADRB2 genotypes in distinct European cohorts; HWE deviation depends on sex (only females are in disequilibrium), and genotypes displaying maximum and minimum relative fitness differ across population samples, suggesting a complex situation possibly involving epistasis or maternal selection. Overall, our data indicate that future association studies involving ADRB2 will benefit from taking into account ethnicity-specific haplotype distributions and sex-based effects. With respect to ADRB3, our data indicate that the gene has been subjected to a selective sweep in African populations, the Trp64 variant possibly representing the selection target. Given the previous association of the ancestral ADRB3 Arg64 allele with obesity and type 2 diabetes, dietary adaptations might represent the underlying selective force.

Sensitization to Ascaris lumbricoides and severity of childhood asthma in Costa Rica

BACKGROUND

Little is known about sensitization (defined as a positive IgE) to helminths and disease severity in patients with asthma.

OBJECTIVES

To examine the relationship between sensitization (defined as a positive IgE) to Ascaris lumbricoides and measures of asthma morbidity and severity in a Costa Rican population with low prevalence of parasitic infection but high prevalence of parasitic exposure.

METHODS

Cross-sectional study of 439 children (ages 6 to 14 years) with asthma. Linear regression and logistic regression were used for the multivariate statistical analysis.

RESULTS

After adjustment for parental education and other covariates, sensitization to Ascaris lumbricoides was associated with having at least 1 positive skin test to allergens (odds ratio, 5.15; 95% CI, 2.36-11.21; P < .001), increased total serum IgE and eosinophils in peripheral blood, reductions in FEV(1) and FEV(1)/forced vital capacity, increased airway responsiveness and bronchodilator responsiveness, and hospitalizations for asthma in the previous year (odds ratio, 3.08; 95% CI, 1.23-7.68; P = .02).

CONCLUSION

Sensitization to Ascaris lumbricoides is associated with increased severity and morbidity of asthma among children in Costa Rica. This association is likely mediated by an increased degree of atopy among children with asthma who are sensitized to Ascaris.

CLINICAL IMPLICATIONS

In areas with a low prevalence of helminthiasis such as Costa Rica, Ascaris sensitization may be an important marker of severe atopy and disease morbidity in children with asthma.

The genetics of bronchial asthma in children

Bronchial asthma is a chronic inflammatory disease based on an inappropriate stimulation of the immune system, for instance by environmental aeroallergens. It is characterised by bronchial hyperreactivity, reversible airway obstruction and mucus overproduction. During the last decades bronchial asthma has become the most common disease of childhood. Accordingly, many epidemiological and genetic studies have dealt with its origin. In fact, hundreds of genome-wide linkage analyses and association studies have identified several chromosomal regions harbouring asthma susceptibility genes like chromosome 2q, 5q, 6q, 11q, 12q and 13q. Also about 100 candidate genes for asthma have been described. However, not all of them have been confirmed in independent studies. Besides the genetic predisposition environmental factors play an important role in the development of allergic diseases. Studies predominantly performed in farmer children have shown that exposure to bacterial endotoxin early in life reduces the risk to develop asthma or atopy later on. Thus, recent studies focussed also on the interaction of genes variants with environmental factors which is summarised under the term genetic epidemiology. Further dissection of asthma genetics and its complex interaction with surrounding factors will hopefully help us in the development of new very specific drugs. In addition, the generation of a genetic risk profile for bronchial asthma should enable us for the first time to take well-directed preventive measurements early in live.

Efficacy of tricyclic antidepressant is associated with beta2-adrenoceptor genotype in patients with interstitial cystitis

We examined the relationship between the Arg16Gly polymorphism of beta2-adrenoceptor (ADRB2) and the efficacy of tricyclic antidepressant therapy in patients with interstitial cystitis (IC). We studied 55 IC patients and 113 controls. The IC patients were treated with imipramine hydrochloride, and the efficacy of treatment was categorized by patients' satisfaction (no change, fair, or good). Genomic DNA was extracted from the controls and IC patients, and the Arg16Gly polymorphism of ADRB2 was analyzed. The Arg16Gly polymorphism showed a significant difference in prevalence between IC patients and controls, and Arg/Arg was associated with increase in the risk of IC than Arg/Gly or Gly/Gly. Regarding the tricyclic antidepressant therapy, there was a significant difference in the prevalence of this polymorphism between IC patients with no change or a fair response to treatment and controls, and Arg/Arg was associated with decrease in the response rate to tricyclic antidepressant therapy than Arg/Gly or Gly/Gly. Therefore, these results suggest that the Arg16Gly polymorphism of ADRB2 is related to down-regulation of ADRB2 expression in the detrusor muscle, so that the response of IC to tricyclic antidepressant therapy depends on the Arg16Gly polymorphism.

Association between beta2-adrenergic receptor genetic polymorphisms and total serum IgE in asthmatic patients of Chinese Han nationality

BACKGROUND

beta(2)-Adrenergic receptor (beta(2)-AR) polymorphisms occurring at amino acid position 16 (Arg-Gly) and 27 (Gln-Glu) are known to be functionally relevant and also disease-modifying in subjects with asthma. It has been found in Caucasoid asthmatic patients that the Gln27 genotype beta(2)-AR was associated with an increase in total serum IgE levels. The association between beta(2)-AR genetic polymorphisms and total serum IgE in asthmatic patients of Chinese Han nationality remains to be established.

OBJECTIVES

It was the aim of this study to investigate the association between beta(2)-AR genetic polymorphisms and total serum IgE in asthmatic patients of Chinese Han nationality.

METHODS

All 59 asthmatic patients investigated (27 males and 32 females, aged between 16 and 60 years) were people of Chinese Han nationality. They were tested for their total serum IgE levels with the enzyme-linked immunosorbent assay test, and beta(2)-AR genetic polymorphisms were tested with the polymerase chain reaction allele-specific oligonucleotide hybridization assay.

RESULTS

There was a significant difference of serum IgE levels among three beta(2)-AR 27 loci groups (p < 0.0001), with the highest IgE level [(1.24 +/- 0.25) x 10(6) IU/l] in the Gln/Gln group and the lowest IgE level [(0.48 +/- 0.06) x 10(6) IU/l] in the Glu/Glu group. No polymorphism of beta(2)-AR 16 loci was found to be associated with total serum IgE (p > 0.05).

CONCLUSIONS

Our research suggested that in asthmatic patients of Chinese Han nationality, the beta(2)-AR genetic polymorphism at 27 loci could be associated with serum IgE levels and it might therefore play an important role in the determination of phenotypes of bronchial asthma.

Asthma and current intestinal parasite infection: systematic review and meta-analysis

RATIONALE

Epidemiologic studies suggest that intestinal parasite infections may protect against asthma.

OBJECTIVES

A systematic review and meta-analysis of epidemiologic studies to determine whether total or species-specific current parasite infection is associated with a reduced risk of asthma or wheeze.

METHODS

We searched MEDLINE, EMBASE, and CINAHL (up to January 2006); reviews; and reference lists from publications, with no language restrictions. We included studies that reported asthma or wheeze as an outcome measure and ascertained parasite infection by fecal examination. We estimated pooled odds ratios (OR) and 95% confidence intervals (CI) using data extracted from published papers, or where available, original data provided by authors, using random effect models.

MEASUREMENTS AND MAIN RESULTS

Thirty-three studies met the inclusion criteria. Infection with any parasite was associated with a small, nonsignificant increase in asthma risk (OR, 1.24; 95% CI, 0.98-1.57; 29 studies). In species-specific analysis, Ascaris lumbricoides was associated with significantly increased odds of asthma (OR, 1.34; 95% CI, 1.05-1.71; 20 studies), while hookworm infection was associated with a significantly strong reduction (OR, 0.50; 95% CI, 0.28-0.90; 9 studies) that was directly and significantly related to infection intensity (p < 0.001; OR for highest tertile of infection, 0.34; 95% CI, 0.19-0.62). Other species had no significant effects on asthma. Infection effects on wheeze were derived from smaller numbers, but revealed a broadly similar pattern of results.

CONCLUSIONS

Parasite infections do not in general protect against asthma, but infection with hookworm may reduce the risk of this disease.

Recall of intestinal helminthiasis by HIV-infected South Africans and avoidance of possible misinterpretation of egg excretion in worm/HIV co-infection analyses

BACKGROUND

Ascariasis and HIV/AIDS are often co-endemic under conditions of poverty in South Africa; and discordant immune responses to the respective infections could theoretically be affecting the epidemic of HIV/AIDS in various ways. It is well-known that sensitisation to helminthic antigens can aggravate or ameliorate several non-helminthic diseases and impair immunisation against cholera, tetanus and tuberculosis. The human genotype can influence immune responses to Ascaris strongly. With these factors in mind, we have started to document the extent of long-term exposure to Ascaris and other helminths in a community where HIV/AIDS is highly prevalent. In more advanced studies, objectives are to analyse relevant immunological variables (e.g. cytokine activity and immunoglobulin levels). We postulate that when Ascaris is hyperendemic, analysis of possible consequences of co-infection by HIV cannot be based primarily on excretion vs non-excretion of eggs.

METHODS

Recall of worms seen in faeces was documented in relation to the age of adult volunteers who were either seropositive (n = 170) or seronegative (n = 65) for HIV. Reasons for HIV testing, deworming treatments used or not used, date and place of birth, and duration of residence in Cape Town, were recorded. Confidence intervals were calculated both for group percentages and the inter-group differences, and were used to make statistical comparisons.

RESULTS

In both groups, more than 70% of participants were aware of having passed worms, often both when a child and as an adult. Most of the descriptions fitted Ascaris. Evidence for significantly prolonged exposure to helminthic infection in HIV-positives was supported by more recall of deworming treatment in this group (p < 0.05). Over 90% of the participants had moved to the city from rural areas.

CONCLUSION

There was a long-term history of ascariasis (and probably other helminthic infections) in both of the groups that were studied. In women in the same community, and in children living where housing and sanitation are better, Ascaris sero-prevalence exceeded egg-prevalence by two- and three-fold, respectively. For ongoing and future analyses of possible consequences of co-infection by Ascaris (and/or other helminths) and HIV/AIDS (and/or other bystander conditions), comparisons must be based mainly on disease-related immunological variables. Especially in adults, comparisons cannot be based only on the presence or absence of eggs in excreta.

A review of the genetic epidemiology of resistance to parasitic disease and atopic asthma: common variants for common phenotypes?

PURPOSE OF REVIEW

An inverse relationship between resistance to certain parasitic diseases and measures of atopy and asthma has long been observed. A possible explanation is that genetic determinants which confer protection against detrimental worm burdens are the same determinants involved in atopic asthma. The focus of this review is to consider the potential candidate genes that have been elucidated as part of molecular, genomic and genetic studies of parasite biology, host-parasite interactions and classic genetic epidemiology studies on parasitic disease and allergic asthma.

RECENT FINDINGS

Comparative studies of the Plasmodium and Schistosoma spp. genomes have revealed a number of proteins that are homologous to humans. A number of linkage and association studies on susceptibility/resistance to parasitic diseases, including malaria and schistosomiasis, overlap with associations that have been identified for susceptibility to atopy and asthma.

SUMMARY

In response to parasitic approaches in maintaining survival, the human host has evolved genetic adaptations that minimize severe manifestations of disease, which conversely appear to contribute to allergic disease. A clearer understanding of this process will elucidate the complex pathways and mechanisms involved in these traits.

Genetic epidemiology of health disparities in allergy and clinical immunology

The striking racial and ethnic disparities in disease prevalence for common disorders, such as allergic asthma, cannot be explained entirely by environmental, social, cultural, or economic factors, and genetic factors should not be ignored. Unfortunately, genetic studies in underserved minorities are hampered by disagreements over the biologic construct of race and logistic issues, including admixture of different races and ethnicities. Current observations suggest that the frequency of high-risk variants in candidate genes can differ between African Americans, Puerto Ricans, and Mexican Americans, and this might contribute to the differences in disease prevalence. Maintenance of certain allelic variants in the population over time might reflect selective pressures in previous generations. For example, significant associations between markers in certain candidate genes (eg, STAT6, ADRB2, and IFNGR1) for traits such as high total IgE levels observed in resistance to extracellular parasitic disease in one population and atopic asthma in another supports the common disease/common variant model for disease. Herein is a discussion of how genetic variants might explain, at least in part, the marked disparities observed in risk to allergic asthma.

Respiratory symptoms in greenlanders living in Greenland and Denmark: a population-based study

BACKGROUND

Knowledge of respiratory diseases in an arctic population with increasingly westernized lifestyles provides the opportunity to obtain new information in this field.

OBJECTIVE

To investigate the influence of environment and lifestyle on the presence of respiratory symptoms in a genetically homogenous population sample living under widely differing conditions.

METHODS

Greenland is a part of Denmark, but its climate is mainly arctic, as opposed to the temperate climate of southern Denmark. A random sample of Inuits who had immigrated to Denmark and Inuits from 3 towns and 4 remote settlements in Greenland were studied. Of the 6,695 invited Inuits, 4,162 (62%) completed a questionnaire concerning respiratory symptoms and risk factors.

RESULTS

Of the 4,162 Inuits, 847 (20%) had respiratory symptoms. Bronchitis was more frequent in the areas of Greenland than in Denmark (26% and 20% vs 13%; P < .001), whereas the pattern of asthma was contradictory (6% and 9% vs 10%; P = .057). Bronchitis was associated with living area (P = .01), tobacco consumption (P < .001), and asthma (P = .001), whereas asthma was related to living area (P = .03), hay fever (P < .001), low intake of whale (P = .04), years in Denmark (P = .09), and bronchitis (P < .001).

CONCLUSIONS

Inuits' prevalence of bronchitis and asthma differed, with a higher frequency of bronchitis and a lower frequency of asthma in Inuits living in Greenland compared with Denmark. Living conditions or areas, diet, tobacco use, climate, and atopy are important for the presence of symptoms.

Genetics of susceptibility to human helminth infection

Recent studies have shown that host genetics is an important determinant of the intensity of infection and morbidity due to human helminths. Epidemiological studies of a number of parasite species have shown that the intensity of infection (worm burden) is a heritable phenotype. The proportion of variance in human worm burden explained by genetic effects varies from 0.21 to 0.44. Human genome scans have identified a locus responsible for controlling Schistosoma mansoni infection intensity on chromosome 5q31-q33, and loci controlling Ascaris lumbricoides intensity on chromosomes 1 and 13, although the genes involved have not yet been identified. There is also evidence for genetic control of pathology due to S. mansoni, and linkage has been reported to a region containing the gene for the interferon-gamma receptor 1 subunit. There is some evidence for genetic control of filarial infection, though little information on filarial disease. Association studies have provided evidence for major histocompatibility complex control of pathology in schistosomiasis and onchocerciasis. Recent candidate gene studies suggest a role of other immune response genes in controlling helminth infection and pathology, but require replication. Identification of the genetic loci involved may be important in the understanding of helminth epidemiology and the mechanisms of resistance and pathology.

Pharmacology and physiology of human adrenergic receptor polymorphisms

Adrenergic receptors are expressed on virtually every cell type in the body and are the receptors for epinephrine and norepinephrine within the sympathetic nervous system. They serve critical roles in maintaining homeostasis in normal physiologic settings as well as pathologic states. These receptors are also targets for therapeutically administered agonists and antagonists. Recent studies have shown that at least seven adrenergic receptor subtypes display variation in amino acid sequence in the human population due to common genetic polymorphisms. Variations in potential regulatory domains in noncoding sequence are also present. Here, we review the consequences of these polymorphisms in terms of signaling, human physiology and disease, and response to therapy.

Sequence variation in the promoter region of the cholinergic receptor muscarinic 3 gene and asthma and atopy

BACKGROUND

Muscarinic acetylcholine receptors are members of the superfamily of G protein-coupled, 7 transmembrane- spanning proteins. They are important in the development of airway hyperresponsiveness. In the lung the M3 receptor, encoded by the cholinergic receptor muscarinic 3 gene, is present in airway smooth muscle and mediates smooth muscle contraction.

OBJECTIVE

We considered the cholinergic receptor muscarinic 3 gene as a possible candidate gene for bronchial asthma and initiated studies to identify polymorphisms in the promoter region.

METHOD

We identified 4 single-nucleotide polymorphisms (-708A/G, -627G/C, -513C/A, and -492C/T) and 2 short tandem repeat polymorphisms, a tetranucleotide (CTTT)12-20 and a dinucleotide (GT)6-19 repeat.

RESULTS

None of the identified single nucleotide polymorphisms were significantly more frequent in asthmatic patients (n = 76) compared with in healthy control subjects (n = 81). Furthermore, there was no evidence for nonrandom transmission of short tandem repeat polymorphism haplotypes to individuals with asthma or bronchial hyperresponsiveness (P >.50) in a large Hutterite pedigree. However, there was significant nonrandom transmission of haplotypes to individuals with skin test reactivity to cockroach allergens (global transmission disequilibrium test: chi2 = 38.55, P =.013).

CONCLUSIONS

These results suggest a possible role for this gene in atopic disorders.

Molecular analysis of adrenergic receptor genes and interleukin-4/interleukin-4 receptor genes in patients with interstitial cystitis

PURPOSE

Interstitial cystitis is a chronic and sterile inflammatory disease of the bladder. Clinically many patients with interstitial cystitis also have allergic or autoimmune diseases. Recent studies have suggested that allelic variations in the adrenergic receptor beta2 gene, the interleukin (IL)-4 gene and its receptor gene are closely associated with immune diseases. Therefore, we studied adrenergic receptor genes alpha1d (ADRA1d), beta2 (ADRB2) and beta3 (ADRB3), and IL-4/IL-4 receptor genes in patients with interstitial cystitis.

MATERIALS AND METHODS

We studied 55 patients with interstitial cystitis and 228 controls. Genomic DNA was extracted from a whole blood sample collected from each subject. We analyzed 5 gene polymorphisms (G404781T, Arg16Gly, Trp64Arg, C589T and Ile50Val) per gene (ADRA1d, ADRB2, ADRB3, IL-4 and IL-4 receptor, respectively) and their relationship to interstitial cystitis.

RESULTS

The frequency of the Arg/Arg genotype of the ADRB2 gene and the TT genotype of the IL-4 gene were significantly higher in patients with interstitial cystitis than in controls. A significant difference of ADRA1d genotype prevalence was also observed. However, there were no remarkable differences of IL-4 receptor or ADRB3 genotype prevalences.

CONCLUSIONS

Variants of the ADRB2, ADRA1d and IL-4 genes may be related to a predisposition to interstitial cystitis.

Risk factors and epidemiology

What we know: No one gene is a major cause of asthma. Some racial groups are more at risk of asthma than others. Early exposure to domestic animals appears to reduce the chance of developing asthma. Good hygiene may increase the likelihood of asthma. Impaired early airway function predisposes to asthma. What we need to know: How do several minor genetic factors combine to increase the risk of asthma in individuals and in population groups? Does early exposure to allergens promote sensitisation or tolerance? How do viruses precipitate asthma? Can acute asthma be treated by treating viral respiratory infections? Does impaired early airway function predispose to asthma throughout childhood?

Genotype-phenotype correlations with personality traits of healthcare professionals: a new use for the Human Genome Project

OBJECTIVE

To describe the genetic basis of various personality traits.

DESIGN

Prospective, blinded cohort study comparing questionnaire-reported personality traits with candidate genes for temperament, as revealed by genetic mapping in the Human Genome Project. Non-supervised questionnaires were mailed to MJA subscribers. DNA extracted from newborn screening blood samples of all New South Wales participants was used to perform mutation analysis for candidate personality genes.

SETTING

Tertiary medical care in New South Wales, 1 April 2000 to 1 April 2001.

PARTICIPANTS

Healthcare professionals who admitted to reading the MJA on at least a semi-regular (monthly) basis.

MAIN OUTCOME MEASURES

Correlations between occupation, personality and gene mutations were sought using a LOD score in comparison with a classic Poisson d'avril distribution.

RESULTS

Mutations were identified that suggested the existence of genes determining several personality traits. Genes coding for belligerence (bel), charisma (lub), cynicism (dub), housekeeping (vac and uum), lack of personality (dul-1), obsessive-compulsive behaviour (pic-e) and gullibility (suk-r) are described. These were found to be selectively represented in certain members of the healthcare profession.

CONCLUSIONS

The seven most important healthcare personality genes have now been described for posterity.

Interactions between genes and environmental factors in asthma and atopy: new developments

Asthma and associated phenotypes are complex traits most probably caused by an interaction of multiple disease susceptibility genes and environmental factors. Major achievements have occurred in identifying chromosomal regions and polymorphisms in candidate genes linked to or associated with asthma, atopic dermatitis, IgE levels and response to asthma therapy. The aims of this review are to explain the methodology of genetic studies of multifactorial diseases, to summarize chromosomal regions and polymorphisms in candidate genes linked to or associated with asthma and associated traits, to list genetic alterations that may alter response to asthma therapy, and to outline genetic factors that may render individuals more susceptible to asthma and atopy due to environmental changes.

Genetic polymorphisms of adrenergic receptors

Recent advances in molecular biology have enhanced the understanding of adrenergic receptors. They have allowed the characterization of the several subtypes of adrenergic receptors expressed and have expanded the research about the potential physiologic functions they mediate. Furthermore, variant forms, or polymorphims, of the genes that code for these receptors are being identified. These genetic variants may or may not result in functional differences in the receptors they encode. There is obvious interest in determining the physiologic and clinical relevance of these polymorphisms. The purpose of this review is to describe these polymorphisms and the often contradictory literature pertaining to their clinical significance. Progress in this area is being made at a rapid pace. As the allele-disease relations become less equivocal, it might be possible to predict individual differences in susceptibility to a disease, disease prognosis, and response to treatment.

Evolutionary adaptation of inflammatory immune responses in human beings

Modern man's ancestors lived in an environment where infectious, tropical diseases would have been endemic. We postulate that this relatively hostile environment would have caused genetic selection for increased proinflammatory immune responses. On migrating to temperate regions, pronounced proinflammatory responses would have been less important and selected against due to increased mortality from overly vigorous responses to harmless environmental agents. This hypothesis is supported by the observation that proinflammatory alleles in several genes involved in inflammation are more prevalent in populations with long-term tropical ancestry than those with long-term residence in temperate regions. In addition, when the former populations relocate from a tropical to a temperate region, they have a higher incidence of allergic inflammatory diseases than the latter populations. These observations suggest that there may be general patterns of recent evolutionary adaptation of the human immune system to particular regions and that these adaptations can produce differences in disease susceptibility.