Immune modulation by rural exposures and allergy protection

BACKGROUND

Growing up on traditional farms protects children from the development of asthma and allergies. However, we have identified distinct asthma-protective factors, such as poultry exposure. This study aims to examine the biological effect of rural exposure in China.

METHODS

We recruited 67 rural children (7.4 ± 0.9 years) and 79 urban children (6.8 ± 0.6 years). Depending on the personal history of exposure to domestic poultry (DP), rural children were further divided into those with DP exposure (DP+ , n = 30) and those without (DP- , n = 37). Blood samples were collected to assess differential cell counts and expression of immune-related genes. Dust samples were collected from poultry stables inside rural households. In vivo activities of nasal administration of DP dust extracts were tested in an ovalbumin-induced asthma model.

RESULTS

There was a stepwise increase in the percentage of eosinophils (%) from rural DP+ children (median = 1.65, IQR = [1.28, 3.75]) to rural DP- children (3.40, [1.70, 6.50]; DP+ vs. DP- , p = .087) and to the highest of their urban counterparts (4.00, [2.00, 7.25]; urban vs. DP+ , p = .017). Similarly, rural children exhibited reduced mRNA expression of immune markers, both at baseline and following lipopolysaccharide (LPS) stimulation. Whereas LPS stimulation induced increased secretion of Th1 and proinflammatory cytokines in rural DP+ children compared to rural DP- children and urban children. Bronchoalveolar lavage of mice with intranasal instillation of dust extracts from DP household showed a significant decrease in eosinophils as compared to those of control mice (p < .05). Furthermore, DP dust strongly inhibited gene expression of Th2 signature cytokines and induced IL-17 expression in the murine asthma model.

CONCLUSIONS

Immune responses of rural children were dampened compared to urban children and those exposed to DP had further downregulated immune responsiveness. DP dust extracts ameliorated Th2-driven allergic airway inflammation in mice. Determining active protective components in the rural environment may provide directions for the development of primary prevention of asthma.

From preschool wheezing to asthma: Environmental determinants

Wheezing is common among preschool children, representing a group of highly heterogeneous conditions with varying natural history. Several phenotypes of wheezing have been proposed to facilitate the identification of young children who are at risk of subsequent development of asthma. Epidemiological and immunological studies across different populations have revealed the key role of environmental factors in influencing the progression from preschool wheezing to childhood asthma. Significant risk factors include severe respiratory infections, allergic sensitization, and exposure to tobacco smoke. In contrast, a farming/rural environment has been linked to asthma protection in both human and animal studies. Early and intense exposures to microorganisms and microbial metabolites have been demonstrated to alter host immune responses to allergens and viruses, thereby driving the trajectory away from wheezing illness and asthma. Ongoing clinical trials of candidate microbes and microbial products have shown promise in shaping the immune function to reduce episodes of viral-induced wheezing. Moreover, restoring immune training may be especially important for young children who had reduced microbial exposure due to pandemic restrictions. A comprehensive understanding of the role of modifiable environmental factors will pave the way for developing targeted prevention strategies for preschool wheezing and asthma.

Meteorin-β/Meteorin like/IL-41 attenuates airway inflammation in house dust mite-induced allergic asthma

We sought to examine the regulatory effect of Meteorin-β (Metrnβ)/Meteorin like (Metrnl)/IL-41 on lung inflammation in allergic asthma. We found that Metrnβ was elevated significantly in asthmatic patients and in mice with allergic asthma induced by house dust mite (HDM) extract. Upon exposure to HDM, Metrnβ was secreted predominantly by airway epithelial cells and inflammatory cells, including macrophages and eosinophils. The increased Metrnβ effectively blocked the development of airway hyperreactivity (AHR) and decreased inflammatory cell airway infiltration and type 2 cytokine production, which was associated with downregulated DC-mediated adaptive immune responses. Moreover, Metrnβ impaired the maturation and function of bone marrow-derived dendritic cells in vitro. Asthmatic mice adoptively transferred with dendritic cells isolated from Metrnβ-treated allergic mice displayed decreased AHR, airway inflammation, and lung injury. Metrnβ also displayed anti-inflammatory properties in immunodeficient SCID mice with allergic asthma and in in vitro 3D ALI airway models. Moreover, blockade of Metrnβ by anti-Metrnβ antibody treatment promoted the development of allergic asthma. These results revealed the unappreciated protective roles of Metrnβ in alleviating DC-mediated Th2 inflammation in allergic asthma, providing the novel treatment strategy of therapeutic targeting of Metrnβ in allergic asthma.

Guidelines for the prevention and management of children and adolescents with COVID-19

Children are the future of the world, but their health and future are facing great uncertainty because of the coronavirus disease 2019 (COVID-19) pandemic. In order to improve the management of children with COVID-19, an international, multidisciplinary panel of experts developed a rapid advice guideline at the beginning of the outbreak of COVID-19 in 2020. After publishing the first version of the rapid advice guideline, the panel has updated the guideline by including additional stakeholders in the panel and a comprehensive search of the latest evidence. All recommendations were supported by systematic reviews and graded using the Grading of Recommendations Assessment, Development and Evaluation (GRADE) system. Expert judgment was used to develop good practice statements supplementary to the graded evidence-based recommendations. The updated guideline comprises nine recommendations and one good practice statement. It focuses on the key recommendations pertinent to the following issues: identification of prognostic factors for death or pediatric intensive care unit admission; the use of remdesivir, systemic glucocorticoids and antipyretics, intravenous immunoglobulin (IVIG) for multisystem inflammatory syndrome in children, and high-flow oxygen by nasal cannula or non-invasive ventilation for acute hypoxemic respiratory failure; breastfeeding; vaccination; and the management of pediatric mental health.

CONCLUSION

This updated evidence-based guideline intends to provide clinicians, pediatricians, patients and other stakeholders with evidence-based recommendations for the prevention and management of COVID-19 in children and adolescents. Larger studies with longer follow-up to determine the effectiveness and safety of systemic glucocorticoids, IVIG, noninvasive ventilation, and the vaccines for COVID-19 in children and adolescents are encouraged.

WHAT IS KNOWN

• Several clinical practice guidelines for children with COVID-19 have been developed, but only few of them have been recently updated. • We developed an evidence-based guideline at the beginning of the COVID-19 outbreak and have now updated it based on the results of a comprehensive search of the latest evidence.

WHAT IS NEW

• The updated guideline provides key recommendations pertinent to the following issues: identification of prognostic factors for death or pediatric intensive care unit admission; the use of remdesivir, systemic glucocorticoids and antipyretics, intravenous immunoglobulin for multisystem inflammatory syndrome in children, and high-flow oxygen by nasal cannula or non-invasive ventilation for acute hypoxemic respiratory failure; breastfeeding; vaccination; and the management of pediatric mental health.

Environmental Influences and Allergic Diseases in the Asia-Pacific Region: What Will Happen in Next 30 Years?

Asia-Pacific is a populous region with remarkable variations in socioeconomic development and environmental exposure among countries. The prevalence rates of asthma and allergic rhinitis appear to have recently reached a plateau in Western countries, whereas they are still increasing in many Asian countries. Given the large population in Asia, even a slight increase in the prevalence rate will translate into an overwhelming number of patients. To reduce the magnitude of the increase in allergic diseases in next few decades in Asia, we must understand the potential factors leading to the occurrence of these disorders and the development of potential preventive strategies. The etiology of allergic disorders is likely due to complex interactions among genetic, epigenetic, and environmental factors for the manifestations of inappropriate immune responses. As urbanization and industrialization inevitably progress in Asia, there is an urgent need to curtail the upcoming waves of the allergy epidemic. Potentially modifiable risk exposure, such as air pollution, should be minimized through timely implementation of effective legislations. Meanwhile, re-introduction of protective factors that were once part of the traditional farming lifestyle might give new insight into primary prevention of allergy.

Comparison of Clinical Characteristics Among COVID-19 and Non-COVID-19 Pediatric Pneumonias: A Multicenter Cross-Sectional Study

Background

The pandemic of Coronavirus Disease 2019 (COVID-19) brings new challenges for pediatricians, especially in the differentiation with non-COVID-19 pneumonia in the peak season of pneumonia. We aimed to compare the clinical characteristics of pediatric patients with COVID-19 and other respiratory pathogens infected pneumonias.

Methods

We conducted a multi-center, cross-sectional study of pediatric inpatients in China. Based on pathogenic test results, pediatric patients were divided into three groups, including COVID-19 pneumonia group, Non-COVID-19 viral (NCV) pneumonia group and Non-viral (NV) pneumonia group. Their clinical characteristics were compared by Kruskal-Wallis H test or chi-square test.

Results

A total of 636 pediatric pneumonia inpatients, among which 87 in COVID-19 group, 194 in NCV group, and 355 in NV group, were included in analysis. Compared with NCV and NV patients, COVID-19 patients were older (median age 6.33, IQR 2.00-12.00 years), and relatively fewer COVID-19 patients presented fever (63.2%), cough (60.9%), shortness of breath (1.1%), and abnormal pulmonary auscultation (18.4%). The results were verified by the comparison of COVID-19, respiratory syncytial virus (RSV) and influenza A (IFA) pneumonia patients. Approximately 42.5%, 44.8%, and 12.6% of the COVID-19 patients presented simply ground-glass opacity (GGO), simply consolidation, and the both changes on computed tomography (CT) scans, respectively; the proportions were similar as those in NCV and NV group (p>0.05). Only 47.1% of COVID-19 patients had both lungs pneumonia, which was significantly lower than that proportion of nearly 80% in the other two groups. COVID-19 patients presented lower proportions of increased white blood cell count (16.5%) and abnormal procalcitonin (PCT) (10.7%), and a higher proportion of decreased lymphocyte count (44.0%) compared with the other two groups.

Conclusion

Majority clinical characteristics of pediatric COVID-19 pneumonia patients were milder than non-COVID-19 patients. However, lymphocytopenia remained a prominent feature of COVID-19 pediatric pneumonia.

Consensus on DEfinition of Food Allergy SEverity (DEFASE) an integrated mixed methods systematic review

BACKGROUND AND AIMS

The term "Food Allergy" refers to a complex global health problem with a wide spectrum of severity. However, a uniform definition of severe food allergy is currently missing. This systematic review is the preliminary step towards a state-of-the-art synopsis of the current evidence relating to the severity of IgE-mediated food allergy; it will inform attempts to develop a consensus to define food allergy severity by clinicians and other stakeholders.

METHODS

We undertook a mixed-methods systematic review, which involved searching 11 international biomedical databases for published studies from inception to 31 December 2019. Studies were independently screened against pre-defined eligibility criteria and critically appraised by established instruments. The substantial heterogeneity of included studies precluded meta-analyses and, therefore, narrative synthesis of quantitative and qualitative data was performed.

RESULTS

We found 23 studies providing eligible primary data on symptom-specific severity of food allergic reactions, and 31 previously published symptom-severity scoring systems referred to food allergic reactions. There were seven studies which assessed quality-of-life measures in patients (and family members) with different food allergy severity and two studies that investigated the economic burden of food allergy severity. Overall, the quality and the global rating of all included studies were judged as being moderate.

CONCLUSIONS

There is heterogeneity among severity scoring systems used and even outcomes considered in the context of severity of food allergy. No score has been validated. Our results will be used to inform the development of an international consensus to define the severity of food allergy.

SYSTEMATIC REVIEW REGISTRATION

A protocol was prospectively registered with the International Prospective Register of Systematic Reviews (PROSPERO) database with the registration number CRD42020183103 (https://www.crd.york.ac.uk/prospero/#recordDetails).

Consensus on DEfinition of Food Allergy SEverity (DEFASE): Protocol for a systematic review

Background and aims

The term “Food Allergy” refers to a complex global health problem with a wide spectrum of severity. However, a uniform definition of severe food allergy is currently missing. This systematic review is the preliminary step towards a state-of-the-art synopsis of the current evidence relating to the severity of IgE-mediated food allergy; it will inform attempts to develop a consensus to define food allergy severity by clinicians and other stakeholders.

Methods

We will undertake a systematic review, which will involve searching international biomedical databases for published studies. Studies will be independently screened against pre-defined eligibility criteria and critically appraised by established instruments. Data will be descriptively and, if possible and applicable, quantitatively synthesised.

Ethics and dissemination

This study does not require any specific ethical approval since it is a systematic review. We plan to report results from this systematic review in a peer reviewed journal. These results will be used to inform the development of an international consensus to define severe food allergy. Author's potential conflicts of interest are clearly stated.

PROSPERO registration number

CRD42020183103.

COVID-19: lessons to date from China

The pandemic due to a novel coronavirus has been sweeping across different regions of the globe since January 2020. Early reports of this infection due to severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) consisted of mostly adult patients. As the outbreak spreads rapidly beyond the epicentre of Wuhan, it becomes clear that infants and children of all ages are susceptible to this infection. In China, there have been more than 1200 paediatric cases. Most paediatric patients acquire the infection through household contact with infected adults. The disease in children is usually self-limiting and most infected children will recover uneventfully within 7-10 days. Other than symptoms of the respiratory tract, many children may present with gastrointestinal symptoms. Older children are more likely to have asymptomatic infection. Although deaths related to SARS-CoV-2 are rarely reported in the paediatric age group, young children and those with underlying medical conditions are more likely to develop severe illness. Only a small fraction of neonates born to infected mother would acquire the virus by vertical transmission. Because a large proportion of children and adolescents may have asymptomatic or mildly symptomatic infection, children are likely to play an important role in community transmission of this infection. Screening of children who have a definitive contact history will facilitate early diagnosis and isolation of all infected children. This review summarises the lessons learned in China with regard to the current understanding of SARS-CoV-2 infection in the paediatric population.

SARS-CoV-2 infection in children - Understanding the immune responses and controlling the pandemic

In December 2019, a cluster of patients with severe pneumonia caused by a novel coronavirus (SARS-CoV-2) emerged in the city of Wuhan, China. The disease is now termed coronavirus disease 2019 (COVID-19). In the early reports, the patients were mainly middle-aged and elderly men, and children appeared to be less susceptible to this infection. With modern and efficient transportation, the disease quickly spread to almost all corners of the world and the mortality far exceeds that caused by severe acute respiratory syndrome (SARS) coronavirus or Middle East respiratory syndrome (MERS) coronavirus. As the number of children with COVID-19 gradually increases, the disease has been documented in premature babies, infants, children, and adolescents. Severe and fatal cases in children are relatively rare. The burden of disease in children has been relatively low, but the high proportions of asymptomatic or mildly symptomatic infections in children deserve careful attention. A clear understanding of the immune responses to the virus in children and the transmission potential of asymptomatic children is of paramount importance for the development of specific treatments and vaccine in order to effectively control the ongoing pandemic.

Prolonged viral shedding in feces of pediatric patients with coronavirus disease 2019

OBJECTIVE

To determine the dynamic changes of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) RNA in respiratory and fecal specimens in children with coronavirus disease 2019 (COVID-19).

METHODS

From January 17, 2020 to February 23, 2020, three paediatric cases of COVID-19 were reported in Qingdao, Shandong Province, China. Epidemiological, clinical, laboratory, and radiological characteristics and treatment data were collected. Patients were followed up to March 10, 2020, and dynamic profiles of nucleic acid testing results in throat swabs and fecal specimens were closely monitored.

RESULTS

Clearance of SARS-CoV-2 in respiratory tract occurred within two weeks after abatement of fever, whereas viral RNA remained detectable in stools of pediatric patients for longer than 4 weeks. Two children had fecal SARS-CoV-2 undetectable 20 days after throat swabs showing negative, while that of another child lagged behind for 8 days.

CONCLUSIONS

SARS-CoV-2 may exist in children's gastrointestinal tract for a longer time than respiratory system. Persistent shedding of SARS-CoV-2 in stools of infected children raises the possibility that the virus might be transmitted through contaminated fomites. Massive efforts should be made at all levels to prevent spreading of the infection among children after reopening of kindergartens and schools.

Frequency of food group consumption and risk of allergic disease and sensitization in schoolchildren in urban and rural China

BACKGROUND

Diet is a potential determinant of allergic diseases.

OBJECTIVE

To examine in schoolchildren the association between food intake and allergic diseases and determine whether there is effect of environment - rural vs. urban.

METHODS

A questionnaire survey was performed in 11 473 children aged 7-12 years in 20 schools from urban Guangzhou and rural Shaoguan, China. A nested case-control group, 402 from Guangzhou and 349 from Shaoguan, was recruited. Food ingestion frequency data were collected. Serum-specific IgE to 34 food and airborne allergens was determined. Associations between food ingestion frequency and clinical outcomes were sought by logistic analyses.

RESULTS

The prevalence of self-reported asthma (6.6% vs. 2.5%), rhinitis (23.2% vs. 5.3%) and eczema (34.1% vs. 25.9%) was significantly higher in Guangzhou subjects compared to Shaoguan, whereas prevalence of food hypersensitivity (9.7% vs. 9.2%) and food allergy (4.0% vs. 3.5%) was not significantly different. In this case-control study, seafood and fruits were two major food groups causing food hypersensitivity. Urban children consumed more milk, egg, chocolate, fruits, vegetable and cereals compared to rural children. Significantly higher percentage of Guangzhou children was sensitized to egg and milk, whereas more Shaoguan children were sensitized to seafood, nuts and seeds, fruit, vegetables, legumes and cereals. High consumption of milk (OR 2.604, 95 CI% 1.569-4.322, P < 0.001) and vegetables (OR 0.382, 95% CI 0.180-0.809, P = 0.012) were positively and reversely associated with asthma, respectively.

CONCLUSION

Difference in prevalence of asthma but not food allergy was observed. Diets of schoolchildren are affected by disease-related modification and country's urbanization. High vegetable intake and low milk intake might protect against asthma.

Prevalence of vitamin D insufficiency among adolescents and its correlation with bone parameters using high-resolution peripheral quantitative computed tomography

Vitamin D deficiency and insufficiency are highly prevalent among adolescents in Hong Kong, which is a sub-tropical city with ample sunshine. Vitamin D level is significantly correlated with key bone density and bone quality parameters. Further interventional studies are warranted to define the role of vitamin D supplementation for improvement of bone health among adolescents.

INTRODUCTION

The relationship between bone quality parameters and vitamin D (Vit-D) status remains undefined among adolescents. The aims of this study were to evaluate Vit-D status and its association with both bone density and bone quality parameters among adolescents.

METHODS

Three hundred thirty-three girls and 230 boys (12-16 years old) with normal health were recruited in summer and winter separately from local schools. Serum 25(OH) Vit-D level, bone density and quality parameters by Dual Energy X-ray Absorptiometry (DXA) and High-Resolution peripheral Quantitative Computed Tomography (HR-pQCT), dietary calcium intake, and physical activity level were assessed.

RESULTS

Sixty-four point seven percent and 11.4 % of subjects were insufficient [25 ≤ 25(OH)Vit-D ≤ 50 nmol/L] and deficient [25(OH)Vit-D < 25 nmol/L] in Vit-D, respectively. The mean level of serum 25(OH)Vit-D in summer was significantly higher than that in winter (44.7 ± 13.6 and 35.9 ± 12.6 nmol/L, respectively) without obvious gender difference. In girls, areal bone mineral density (aBMD) and bone mineral content (BMC) of bilateral femoral necks, cortical area, cortical thickness, total volumetric bone mineral density (vBMD), and trabecular thickness were significantly correlated with 25(OH)Vit-D levels. In boys, aBMD of bilateral femoral necks, BMC of the dominant femoral neck, cortical area, cortical thickness, total vBMD, trabecular vBMD, BV/TV, and trabecular separation were significantly correlated with 25(OH)Vit-D levels.

CONCLUSION

Vit-D insufficiency was highly prevalent among adolescents in Hong Kong with significant correlation between Vit-D levels and key bone density and bone quality parameters being detected in this study. Given that this is a cross-sectional study and causality relationship cannot be inferred, further interventional studies investigating the role of Vit-D supplementation on improving bone health among adolescents are warranted.

House dust mite sensitization is the main risk factor for the increase in prevalence of wheeze in 13- to 14-year-old schoolchildren in Guangzhou city, China

BACKGROUND

Little is known about time trend of prevalence of asthma and the association between the changing prevalence and allergen sensitization in Chinese children.

OBJECTIVE

To determine the changes in prevalence of asthma and allergen sensitization in schoolchildren over a period of 15 years.

METHODS

A total of 6928 schoolchildren aged 13-14 years in 2009 were recruited for the study using the Phase III Protocol of the International Study of Asthma and Allergic disease in Childhood (ISAAC) and 2531 of them underwent skin prick test for seven common aeroallergens. The results were compared with those obtained in the Phase I (1994/95) and III (2001/02) ISAAC studies.

RESULTS

The prevalence of asthma ever and current wheeze increased from 3.9% and 3.4% in 1994, to 4.6% and 4.8% in 2001 (P<0.001), and to 6.9% and 6.1% in 2009 (P ≤ 0.008). The prevalence of higher degree of skin response to house dust mites (HDMs) and cat, and atopic index increased significantly in all children in 2010 when compared with those in 2002 (P<0.001). Prevalence of wheeze remained unchanged in subjects without sensitization to any tested allergen including HDMs (P > 0.05). Sensitization to HDMs, especially Dermatophagoides Pteronyssinus was associated with increase in prevalence of wheeze.

CONCLUSION

The prevalence of wheeze and sensitization to common aeroallergens in secondary schoolchildren in Guangzhou China has increased significantly since 1994. Sensitization to HDMs is an important risk factor associated with the increase in prevalence of wheeze in this group of population in Guangzhou city.

Case-control association study of polymorphisms in the voltage-gated sodium channel genes SCN1A, SCN2A, SCN3A, SCN1B, and SCN2B and epilepsy

High-frequency action potentials are mediated by voltage-gated sodium channels, composed of one large α subunit and two small β subunits, encoded mainly by SCN1A, SCN2A, SCN3A, SCN1B, and SCN2B genes in the brain. These play a key role in epilepsy, with the most commonly mutated gene in epilepsy being SCN1A. We examined whether polymorphisms in the above genes affect epilepsy risk in 1,529 epilepsy patients and 1,935 controls from four ethnicities or locations: Malay, Indian, and Chinese, all from Malaysia, and Chinese from Hong Kong. Of patients, 19 % were idiopathic, 42 % symptomatic, and 40 % cryptogenic. We genotyped 43 polymorphisms: 27 in Hong Kong, 28 in Malaysia, and 12 in both locations. The strongest association with epilepsy was rs3812718, or SCN1A IVS5N+5G>A: odds ratio (OR) = 0.85 for allele G (p = 0.0009) and 0.73 for genotype GG versus AA (p = 0.003). The OR was between 0.76 and 0.87 for all ethnicities. Meta-analysis confirmed the association (OR = 0.81 and p = 0.002 for G, and OR = 0.67 and p = 0.007 for GG versus AA), which appeared particularly strong for Indians and for febrile seizures. Allele G affects splicing and speeds recovery from inactivation. Since SCN1A is preferentially expressed in inhibitory neurons, G may decrease epilepsy risk. SCN1A rs10188577 displayed OR = 1.20 for allele C (p = 0.003); SCN2A rs12467383 had OR = 1.16 for allele A (p = 0.01), and displayed linkage disequilibrium with rs2082366 (r (2) = 0.67), whose genotypes tended toward association with SCN2A brain expression (p = 0.10). SCN1A rs2298771 was associated in Indians (OR = 0.56, p = 0.005) and SCN2B rs602594 with idiopathic epilepsy (OR = 0.62, p = 0.002). Therefore, sodium channel polymorphisms are associated with epilepsy.

Spirometric reference standards for preschool children in Hong Kong

1. Prediction equations and normograms are established using incentive spirometry in a community cohort of 770 Hong Kong Chinese children aged 2 to 6 years. 2. All spirometric parameters depend mainly on standing height. Boys have higher values than girls. 3. Forced expiratory volumes depend on birth weight, place of birth, history of wheezing, and environmental tobacco smoke (ETS) exposure. 4. High urinary cotinine level as a biomarker of ETS exposure is noted in about one tenth of the children. 5. Urinary cotinine level is inversely associated with all spirometric parameters. This supports implementation of the smoking cessation programme.

Respiratory viruses and atypical bacteria triggering severe asthma exacerbation in children

1. Respiratory viruses and atypical bacteria were detected in 51.0% of Hong Kong children with asthma exacerbations, which was significantly higher than the detection rate of 27.3% in children with chronic stable asthma. 2. Co-infections of two or more respiratory pathogens were more commonly found in children with asthma exacerbations (10.7%) than in patients with stable asthma (2.6%). 3. Human rhinovirus infection was a significant risk factor for asthma exacerbations. 4. There was no significant association between the severity of asthma exacerbations and respiratory viral or atypical bacterial infections. 5. Routine use of macrolide antibiotics in the treatment of childhood asthma exacerbations should be discouraged.

Roles of pollution in the prevalence and exacerbations of allergic diseases in Asia

The prevalence of asthma and allergic diseases has been found to be increasingly rapidly, especially in developing countries. Environmental factors have been found to be important contributors to the manifestations of allergic diseases. Air pollution has been extensively studied in different regions of the world. The levels of ambient air pollutants in many Asian countries are very high when compared with those in developed Western countries. However, the prevalence of asthma was relatively low across many Asian countries. Many studies have clearly documented that environmental air pollution is an important factor resulting in exacerbations of asthma. In particular, levels of traffic-related pollutants are increasing rapidly across many Asian countries in parallel with the level of urbanization and economic development. The loss of protective factors associated with a rural environment will further contribute to the adverse effect on patients with allergic diseases such as asthma. In this review the roles of air pollution were examined in relation to the inception and exacerbations of allergic diseases in Asia.

Circulating LL-37 is a biomarker for eczema severity in children

BACKGROUND

Eczema lesions are characterized by impaired expression of antimicrobial peptides such as cathelicidin, which play crucial roles in the innate immune defence against cutaneous infections. LL-37 corresponds to amino acids 134-170 of human cathelicidin and is a multifunctional host defence molecule essential for normal immune responses to infection and tissue injury.

OBJECTIVES

The aim of this study was to investigate the relationship between childhood eczema and circulating LL-37 levels.

METHODS

One hundred and forty-four eczema children and 36 controls were recruited. Eczema severity was assessed by SCORing Atopic Dermatitis (SCORAD) and serum LL-37 concentration measured using enzyme immunoassay. Patients' skin hydration and transepidermal water loss at forearms were measured using Corneometer and Tewameter.

RESULTS

Patients' mean SCORAD was 49.2 and their disease was classified as mild (n=28; 12.8%), moderate (n=95; 43.6%) and severe (n=95; 43.6%). Serum LL-37 concentrations did not differ between eczema patients and controls (mean: 832 pg/mL vs. 952 pg/mL, P=0.471). However, serum LL-37 concentrations increased with increasing eczema severity among the patients (P=0.005 for trend). This biomarker shows weakly positive correlation with patients' objective SCORAD (r=0.207, P=0.013) and age (r=0.170, P=0.041), but not skin hydration or transepidermal water loss (P>0.09). Linear regression confirmed significant association between objective SCORAD and serum LL-37 when adjusted for age and gender as covariates (β=0.171, P=0.038). On the other hand, serum LL-37 did not differ between patients with and without heavy growth of staphylococci (P=0.151).

CONCLUSIONS

Circulating LL-37 may be a biomarker for severity of childhood eczema, which supports the importance of innate immunity in eczema pathogenesis.

Associations of insulin-like growth factor binding protein-3 gene polymorphisms with IGF-I activity and lipid parameters in adolescents

OBJECTIVE

Childhood obesity is a growing global epidemic. Recent studies indicate that obesity and related metabolic traits are highly heritable. Increasing evidence suggests that growth hormone (GH) and the insulin-like growth factor-I (IGF-I) axis have important functions in regulating adiposity and insulin sensitivity. Five single-nucleotide polymorphisms (SNPs) at IGF-binding protein-3 (IGFBP3) were genotyped to find their associations with IGF-1 activity level and common clinical metabolic traits.

PATIENTS AND METHODS

We examined the associations of five SNPs at IGFBP3 with serum IGF-I and IGFBP-3 levels, as well as with obesity-related metabolic traits in 981 Hong Kong Chinese adolescents. Factor analysis was used to reduce the intercorrelated variables to five factor scores indicating body composition, blood pressure, IGF-I activity, triglyceride (TG)+high-density lipoprotein cholesterol (HDL-C) and total cholesterol (TC)+low-density lipoprotein cholesterol (LDL-C) factor scores.

RESULTS

There was a strong association between the -202A/C polymorphism (rs2854744) and IGF-I activity (P=1.2 x 10(-6)) and TC+LDL-C factor scores (P=0.0085), corrected for age and sex. The C allele was associated with decreased IGFBP-3 levels (P=1.21 x 10(-13)), increased IGF-I/IGFBP-3 molar ratio (P=5.22 x 10(-6)) and decreased LDL-C (P=0.020). There was also a significant association between a G/A polymorphism at the 3' flanking sequence (rs13223993) of the IGFBP3 gene and the TG+HDL-C factor score (P=0.0013). The minor A allele carriers of rs13223993 had a lower HDL-C (P=0.0067) level and a tendency toward a high TG level. Haplotype analysis did not increase the significance of associations between single SNPs and phenotypes.

CONCLUSION

Our results support the function of IGFBP3 gene polymorphisms in modulating IGF-I activity and lipid levels in adolescents. Given the prognostic significance of IGF-I, IGFBPs and lipids on risk of diabetes, obesity and cancer, long-term studies are required to clarify the clinical meaning of these findings.

A multi-centre study of candidate genes for wheeze and allergy: the International Study of Asthma and Allergies in Childhood Phase 2

BACKGROUND

Common polymorphisms have been identified in genes suspected to play a role in asthma. We investigated their associations with wheeze and allergy in a case-control sample from Phase 2 of the International Study of Asthma and Allergies in Childhood.

METHODS

We compared 1105 wheezing and 3137 non-wheezing children aged 8-12 years from 17 study centres in 13 countries. Genotyping of 55 candidate single nucleotide polymorphisms (SNPs) in 14 genes was performed using the Sequenom System. Logistic regression models were fitted separately for each centre and each SNP. A combined per allele odds ratio and measures of heterogeneity between centres were derived by random effects meta-analysis.

RESULTS

Significant associations with wheeze in the past year were detected in only four genes (IL4R, TLR4, MS4A2, TLR9, P<0.05), with per allele odds ratios generally <1.3. Variants in IL4R and TLR4 were also related to allergen-specific IgE, while polymorphisms in FCER1B (MS4A2) and TLR9 were not. There were also highly significant associations (P<0.001) between SPINK5 variants and visible eczema (but not IgE levels) and between IL13 variants and total IgE. Heterogeneity of effects across centres was rare, despite differences in allele frequencies.

CONCLUSIONS

Despite the biological plausibility of IgE-related mechanisms in asthma, very few of the tested candidates showed evidence of association with both wheeze and increased IgE levels. We were unable to confirm associations of the positional candidates DPP10 and PHF11 with wheeze, although our study had ample power to detect the expected associations of IL13 variants with IgE and SPINK5 variants with eczema.

The EuroPrevall-INCO surveys on the prevalence of food allergies in children from China, India and Russia: the study methodology

BACKGROUND

Very little is known regarding the global variations in the prevalence of food allergies. The EuroPrevall-INCO project has been developed to evaluate the prevalence of food allergies in China, India and Russia using the standardized methodology of the EuroPrevall protocol used for studies in the European Union. The epidemiological surveys of the project were designed to estimate variations in the prevalence of food allergy and exposure to known or suspected risk factors for food allergy and to compare the data with different European countries.

METHODS

Random samples of primary schoolchildren were recruited from urban and rural regions of China, Russia and India for screening to ascertain possible adverse reactions to foods. Cases and controls were then selected to answer a detailed questionnaire designed to evaluate the possible risk factors of food allergies. Objective evidence of sensitisation including skin-prick test and serum specific IgE measurement was also collected.

RESULTS

More than 37 000 children from the three participating countries have been screened. The response rates for the screening phase ranged from 83% to 95%. More than 3000 cases and controls were studied in the second phase of the study. Further confirmation of food allergies by double blind food challenge was conducted.

CONCLUSIONS

This will be the first comparative study of the epidemiology of food allergies in China, India, and Russia using the same standardized methodology. The findings of these surveys will complement the data obtained from Europe and provide insights into the development of food allergy.

How well do questionnaires perform compared with physical examination in detecting flexural eczema? Findings from the International Study of Asthma and Allergies in Childhood (ISAAC) Phase Two

BACKGROUND

Questionnaires are widely used in epidemiological studies to measure eczema symptom prevalence, but there are concerns regarding their accuracy if used as a diagnostic tool.

OBJECTIVES

To compare the performance of a validated eczema symptom questionnaire and a standardized skin examination protocol employed in the second phase of the International Study of Asthma and Allergies in Childhood (ISAAC).

METHODS

A total of 30,358 schoolchildren aged 8-12 years from 18 countries were examined for flexural eczema. Parents also completed an eczema symptom questionnaire. We compared prevalence estimates at the population level based on the questionnaire vs. physical examination. We also compared the skin examination and the ISAAC questionnaire in making a diagnosis of flexural eczema.

RESULTS

The point prevalences for flexural eczema at centre level based on a single examination were lower than the questionnaire-based 12-month period prevalences (mean centre prevalence 3.9% vs. 9.4%). Correlation between prevalences of both outcome measures was high (r = 0.77, P < 0.001). At the individual level, questionnaire-derived symptoms of 'persistent flexural eczema in the past 12 months' missed < 10% of cases of flexural eczema detected on physical examination. However, between 33% and 100% of questionnaire-based symptoms of 'persistent flexural eczema in the past 12 months' were not confirmed on examination.

CONCLUSIONS

ISAAC questionnaire-derived symptom prevalences are sufficiently precise for comparisons between populations. Where diagnostic precision at the individual level is important, questionnaires should be validated and potentially modified in those populations beforehand, or a standardized skin examination protocol should be used.

Asthma and atopy are associated with chromosome 17q21 markers in Chinese children

BACKGROUND

Single-nucleotide polymorphism (SNP)-based genome-wide association study revealed that markers on chromosome 17q21 were linked to childhood asthma but not atopy in Caucasians, with the strongest signal being detected for the SNP rs7216389 in the ORMDL3 gene. Such association was unknown in Chinese. This study delineated the allele and genotype frequencies of 10 SNPs at chromosome 17q21, and investigated the relationship between these SNPs and asthma and plasma IgE in southern Chinese children.

METHODS

Asthmatic children and non-allergic controls were recruited from pediatric clinics. Their plasma total and aeroallergen-specific IgE concentrations were measured by immunoassay. Ten SNPs on 17q21 region were genotyped by multiplex SNaPshot, and their genotype associations with asthma traits analyzed using multivariate regression.

RESULTS

315 patients and 192 controls were enrolled. The allele frequency for C allele of rs7216389 varied significantly from 0.232 in our controls, 0.389 in Han Chinese to 0.536 in Caucasians. Asthma diagnosis was associated with rs11650680 and five other SNPs including rs7216389 (P = 0.019-0.034), whereas atopy was associated only with rs11650680 (P = 0.0004). Linear regression revealed the covariates for plasma total IgE to be significant for rs11650680 (P = 0.008-0.0002). Haplotypic associations were found with atopy and increased plasma total IgE, with the respective odds ratios and 95% confidence intervals for TTTCCGTT haplotype to be 0.21 and 0.09-0.52 (P = 0.0002) and 0.41 and 0.18-0.90 (P = 0.025).

CONCLUSION

Childhood asthma and atopy are associated with chromosome 17q21 in Chinese, but such association may involve genes other than ORMDL3 in this region.

Identifying uncontrolled asthma in young children: clinical scores or objective variables?

OBJECTIVE

Several international asthma guidelines emphasize the importance of assessing asthma control. However, there is limited data on the usefulness of available assessment tools in indicating disease control in young asthmatics. This study investigated the ability of Chinese version of Childhood Asthma Control Test (C-ACT) and other disease-related factors in identifying uncontrolled asthma (UA) in young children.

METHODS

During the same clinic visit, asthma patients 4 to 11 years of age completed C-ACT and underwent exhaled nitric oxide and spirometric measurements. Blinded to these results, the same investigator assigned Disease Severity Score (DSS) and rated asthma control according to Global Initiative for Asthma.

RESULTS

The mean (SD) age of 113 recruited patients was 9.1 (2.0) years, and 35% of them had UA. C-ACT, DSS and forced expiratory volume in 1 second (FEV(1)) differed among patients with different control status (p < 0.001 for C-ACT and DSS; p = 0.014 for FEV(1)). Logistic regression confirmed that UA was associated with DSS (p < 0.001), PEF (p = 0.002), C-ACT (p = 0.011), and FEV(1) (p = 0.012). By ROC analysis, C-ACT and DSS were the best predictors for UA (p < 0.001), followed by PEF (p = 0.006) and FEV(1) (p = 0.007). When analyzed by the Classification and Regression Tree (CART) approach, the sequential use of DSS and C-ACT had 77% sensitivity and 84% specificity in identifying UA.

CONCLUSIONS

C-ACT is better than objective parameters in identifying young Chinese children with UA.

Asthma and atopy are associated with DEFB1 polymorphisms in Chinese children

Human beta-defensin (HBD)-1 is constitutively expressed in the airway, and hBD-1 plays crucial roles in innate immunity against respiratory pathogens. Asthma was associated with DEFB1 polymorphisms in Caucasians. This study investigates whether three single nucleotide polymorphisms (SNPs) in 5'-untranslated region of DEFB1 are associated with asthma phenotypes in Chinese children. Subjects aged 5-18 years were recruited from general pediatric clinics. Plasma IgE concentrations were measured by immunoassays. DEFB1 SNPs were characterized by restriction fragment length polymorphism. In all, 305 asthmatics and 156 controls were recruited. For asthma diagnosis, atopy and plasma total IgE, higher percentages of subjects with these outcomes had the minor alleles -20A and -52G (P = 0.041-0.0002). For log-transformed total IgE, the covariate was positive and significant for G-20A under recessive model (P = 0.001) and for G-52A under both recessive and codominant models (P = 0.008 and 0.035). The recessive model covariate was also positive and significant (P = 0.020) for C-44G on peripheral blood eosinophil count. The GCA haplotype of DEFB1 was significantly associated with asthma (odds ratio (95% confidence interval): 1.64 (1.05-2.57); P = 0.029). These results suggest that DEFB1 is a candidate gene for asthma and atopy in children.

Quality-of-life assessment in Chinese families with food-allergic children

BACKGROUND

Caucasian families with food-allergic children have a compromised quality of life (QoL) for fear of life-threatening food reactions. Such data are limited in Asian children. Based on our recent questionnaire-based survey, 8.1% of young children recruited from local nurseries and kindergartens had parent-reported adverse food reactions (AFRs).

OBJECTIVE

This study tested the robustness of the Chinese Food Allergy Quality of Life-Parental Burden questionnaire (FAQL-PB) and assessed QoL in families with childhood AFR. The correlations among FAQL-PB items were evaluated by factor analysis.

METHODS

Two hundred and ninety-eight of 3677 children aged 2-7 years had parent-reported AFR, and 197 (66.1%) of them completed the 17 items of our self-administered FAQL-PB. Six hundred and thirty-nine (18.9%) children without AFR returned this questionnaire. Factor analysis was used to delineate the inter-relationship among the FAQL-PB items.

RESULTS

Cronbach alpha for our Chinese FAQL-PB was 0.976, and the median (interquartile range) FAQL-PB scores of children with and without parent-reported AFR were 0.10 (0.02-0.32) and 0 (0-0.18), respectively (P < 0.001). Factor analysis confirmed excellent correlations between FAQL-PB items. The 17 items were clustered into two factors, which explained 79.7% of the total variance. Among children with AFR, FAQL-PB scores increased with increasing numbers of foods that caused AFRs (P < 0.001 for trend). Thirty (15.2%) children had impaired QoL, defined as average item FAQL-PB score > or = 0.5. Impaired QoL was associated with AFR that was caused by >3 foods (P = 0.001), current food avoidance (P = 0.005) and AFR caused by peanut (P = 0.003), egg (P = 0.011) and cow's milk (P = 0.028), and current flexural dermatitis (P = 0.011).

CONCLUSIONS

FAQL-PB is a robust measure of AFR-specific parental QoL, which is impaired in Chinese children with parent-reported AFR. Flexural dermatitis, current food avoidance and AFR caused by multiple foods are independent risk factors for lower parental QoL.

Study of gene-gene interactions for endophenotypic quantitative traits in Chinese asthmatic children

BACKGROUND

Asthma is a complex disease resulting from interactions between multiple genes and environmental factors. Study of gene-gene interactions could provide insight into the pathophysiology of asthma.

METHODS

We investigated the interactions among 18 single-nucleotide polymorphisms in eight candidate genes for plasma total immunoglobulin E (IgE) concentration and peripheral blood (PB) eosinophil count in 298 Chinese asthmatic children and 175 controls. Generalized multifactor dimensionality reduction and generalized linear model were used to analyze gene-gene interactions for the quantitative traits.

RESULTS

A significant interaction was found between R130Q in IL13 and I50V in IL4RA for plasma total IgE concentration, with a cross-validation (CV) consistency of nine of 10 and a prediction error of 41.1% (P = 0.013). Plasma total IgE concentration was significantly higher in the high-risk than the low-risk groups (P < 0.0001). For PB eosinophil count, significant interaction was found between C-431T in TARC and RsaI_in2 in FCERIB, with a CV consistency of nine of 10 and a prediction error of 40.2% (P = 0.009). PB eosinophil count was significantly higher in the high-risk group than the low-risk groups (P < 0.0001). Generalized linear model also revealed significant gene-gene interaction for the above two endophenotypes with P = 0.013 for plasma total IgE concentration and P = 0.029 for PB eosinophil count respectively.

CONCLUSIONS

Our data suggest significant interactions between IL13 and IL4RA for plasma total IgE concentration, and this is the first report to show significant interaction between TARC and FCERIB for PB eosinophil count in Chinese asthmatic children.

Association between candidate genes and lung function growth in Chinese asthmatic children

BACKGROUND

Asthma is caused by a complex interaction between multiple candidate genes and environmental factors. The Childhood Asthma Management Program reported lung function decline in a significant proportion of Caucasian asthmatic children, but such a relation has not been studied in other populations. Our group recently reported that interleukin-13 (IL13), interleukin-4 receptor-alpha and thymus and the activation-regulated chemokine interacted to influence asthma and raised plasma total IgE. However, there has not been any study that has addressed the genetic influences for longitudinal lung function growth.

OBJECTIVE

We studied the longitudinal changes in spirometric variables in Chinese asthmatic children, and investigated the influence and interactions between eight different loci in six candidate genes as well as environmental factors affecting lung function growth in these children.

METHODS

Spirometry was performed at baseline and study completion. Genotyping was performed by restriction fragment length polymorphism. Multi-factor dimensionality reduction (MDR) was used to detect any gene-gene or gene-environment interaction.

RESULTS

We prospectively followed 131 Chinese children, aged 9.9 (3.0) years, for 4.5 (0.8) years. Their mean (standard deviation) baseline forced expiratory volume in 1 s (FEV1) was 98.6 (20.6)% of predicted, and FEV1 to forced vital capacity (FVC) ratio was 77.8 (11.3)%. FEV1 and FVC increased by 210 (115) and 248 (148) mL/year during this study, and these changes were significantly larger among males (P<0.0001). Univariate analysis revealed a significant association between annual FEV1 change and C1570T of signal transducer and activator of transcription 6 gene (STAT6; P=0.009). Linear regression confirmed this finding (P=0.041). Using MDR, we detected a significant 3-locus interaction between IL13 R130Q, ADRB2 R16G and STAT6 C1570T for determining change in FVC (P=0.045).

CONCLUSION

Our data suggest that STAT6 may influence lung function growth in asthmatic children. We also found significant interactions among several atopy-related genetic polymorphisms for influencing FVC change.

Effects of air pollution on asthma hospitalization rates in different age groups in Hong Kong

AIMS

To assess the relationship between levels of ambient air pollutants and hospitalization rates for asthma in Hong Kong (HK).

METHODS

This is a retrospective ecological study. Data of daily emergency hospital admissions to 15 major hospitals in HK for asthma and indices of air pollutants [sulphur dioxide (SO(2)), nitrogen dioxide (NO(2)), ozone (O(3)), particulates with an aerodynamic diameter of <10 microm particulate matter (PM(10)) and 2.5 microm (PM(2.5))] and meteorological variables from January 2000 to December 2005 were obtained from several government departments. Analysis was performed by the generalized additive models with Poisson distribution. The effects of time trend, season, other cyclical factors, temperature and humidity were adjusted. Autocorrelation and overdispersion were corrected.

RESULTS

Altogether, 69 716 admissions were assessed. Significant associations were found between hospital admissions for asthma and levels of NO(2), O(3), PM(10) and PM(2.5). The relative risks (RR) for hospitalization for every 10 microg/m(3) increase in NO(2), O(3), PM(10) and PM(2.5) were 1.028, 1.034, 1.019 and 1.021, respectively, at a lag day that ranged from cumulative lag 0-4 to 0-5. In a multi-pollutant model, O(3) was significantly associated with increased admissions for asthma. The younger age group (0-14 years) tended to have a higher RR for each 10 microg/m(3) increase in pollutants than those aged 15-65 years. The elderly (aged >/=65 years) had a shorter 'best' lag time to develop asthma exacerbation following exposure to pollutants than those aged <65 years.

CONCLUSION

Adverse effects of ambient concentrations of air pollutants on hospitalization rates for asthma are evident. Measures to improve air quality in HK are urgently needed.

Symptoms of asthma and atopic disorders in preschool children: prevalence and risk factors

BACKGROUND

Published epidemiological data suggested that asthma and allergies may be increasing in preschool children. Identification of the risk factors is important for planning possible early intervention to prevent asthma. This study was designed to measure the prevalence of, and risk factors for, asthma and atopic disorders in preschool children from Hong Kong.

METHODS

Children aged 2-6 years living in Hong Kong were recruited through the local nurseries and kindergartens for this study to ascertain the presence of symptoms of asthma and various possible risk factors. The parental questionnaire was developed based on the International Study of Asthma and Allergies in Childhood questionnaire.

RESULTS

A total of 3089 children (1506 boys) from 14 nurseries and kindergartens participated in this study. The prevalence of wheeze ever and current wheeze were 16.7% and 9.3%. Two hundred and thirty-four subjects were born in mainland China and migrated to Hong Kong subsequently. When compared with children born and raised in Hong Kong, children born in mainland China had significantly lower prevalence of current wheeze (3.4% vs. 9.6%, P<0.01). Two environmental factors in the first year of life were associated with wheezing attacks within the last 12 months. They were the use of foam pillow (Odds ratio: 1.45; 95% Confidence interval: 1.04-2.00) and the use of gas as cooking fuel (1.68; 1.03-2.75). Frequent use of paracetamol was also associated with wheezing attack in the past 12 months.

CONCLUSIONS

This study confirms the high prevalence of symptoms of atopic disorders in preschool children from Hong Kong. Early environmental exposure factors are important determinants of subsequent development of asthma symptoms in the preschool years. Further studies are needed to evaluate the possible pathogenetic role of the identified risk factors.

Association of prostaglandin-endoperoxide synthase 2 gene polymorphisms with asthma and atopy in Chinese children

BACKGROUND

Cyclooxygenase-2 (COX-2) plays essential roles in inflammation. Previous studies have suggested associations between prostaglandin-endoperoxide synthase 2 (PTGS2) polymorphisms and prostaglandins production in asthma.

OBJECTIVE

We have investigated the effects of Chinese tagging single nucleotide polymorphisms (SNPs) of PTGS2 on asthma traits in 299 Chinese asthmatic children and 175 controls.

METHODS

Plasma total and allergen-specific IgE were measured by enzyme immunoassay. PTGS2.8473T-->C in the 3'-untranslated region of exon 10 and three tag SNPs covering most of the variations in PTGS2 haplotypes in Chinese were genotyped by restriction fragment length polymorphism.

RESULTS

Among the four SNPs, only PTGS2.8473 showed significant association with asthma (P = 0.034) and atopy (P = 0.005 when compared with non-atopic controls; P = 0.023 with all controls). Carriers of the C allele had a 1.5-fold (95% confidence interval: 1.01-2.30) risk of developing asthma than those homozygous for the T allele. Multivariate regression revealed significant correlations between PTGS2.8473 and forced expiratory volume in 1 s (FEV(1); P = 0.002) and peak expiratory flow rate (PEFR; P = 0.001) with age and gender adjusted. Patients with the C allele of PTGS2.8473 had significantly lower FEV(1) (median: 90.0%vs 98.0%; P = 0.0047) and PEFR (70.0%vs 73.5%; P = 0.0065) than those homozygous for the T allele. No significant association between plasma total and allergen-specific IgE and these SNPs or with their haplotypes was found.

CONCLUSIONS

PTGS2.8473 polymorphism is associated with asthma, atopy and lung function but not plasma IgE in Chinese children. This may help to explore the pharmacogenetics of COX-2 inhibitors.

Exhaled breath condensate levels of eotaxin and macrophage-derived chemokine in stable adult asthma patients

BACKGROUND

Asthma is associated with esoinophilic airway inflammation and overproduction of T-helper type 2 (Th2) lymphocyte-related cytokines.

OBJECTIVE

This study assessed the eosinophil chemoattractant eotaxin and Th2-specific macrophage-derived chemokine (MDC) in the adult asthmatic airway. Eotaxin and MDC levels were determined in exhaled breath condensate (EBC) obtained from adult patients with asthma.

METHODS

Fifty-four asthmatics (20 male, mean (SD) age 40 (12) years and percentage predicted forced expiratory volume in 1 s (FEV(1)) 81.7 (20.8)) and 20 age- and sex-matched controls were studied. EBC was collected using EcoScreen by 10 min of tidal breathing with a nose clip. Concentrations of eotaxin and MDC were measured by ELISA.

RESULTS

Asthma patients on inhaled corticosteroid (ICS) had a higher median interquartile range (IQR) level of eotaxin than the steroid-naïve asthmatics (18.5 (17.7-20.1) vs. 17.9 (17.0-18.6) pg/mL, P=0.02) and controls (18.5 (17.7-20.1) pg/mL vs 17.4 (16.3-18.0) pg/mL, P=0.001). Eotaxin level in EBC had a significant negative correlation with the FEV(1)/forced vital capacity ratio (r=-0.43, P=0.03) in steroid-naïve asthmatics. EBC MDC level was higher in subjects on ICS than the steroid naïve asthmatics (120 (118-125) vs. 117 (116-119) pg/mL, P=0.01) and the controls (120 (118-125) vs. 117 (116-120) pg/mL, P=0.02).

CONCLUSIONS

Eotaxin and MDC could be measured in EBC of adults with asthma. EBC eotaxin and MDC levels were higher in asthmatics on ICS than the steroid-naïve asthmatics or controls. Exhaled chemokines may be potential non-invasive markers for assessing airway inflammation in asthmatics.

Wheezing in Chinese schoolchildren: disease severity distribution and management practices, a community-based study in Hong Kong and Guangzhou

BACKGROUND

Asthma is a common chronic disease and information on its management practices at the community level is helpful in identifying problems and improving asthma care.

OBJECTIVE

To assess the severity status and management of the asthma symptom of wheeze of children at the community level in Hong Kong (HK) and Guangzhou (GZ).

METHODS

Cross-sectional study of children aged 10 years using the International Study of Asthma and Allergic disease in Childhood (ISAAC Phase II protocol). Asthma management and lung function were assessed in 178 (98 from HK and 80 from GZ) randomly selected children with wheeze over the past 12 months.

RESULTS

Eighty-three percent, 11%, 6% and 0% of children suffered from intermittent, mild persistent, moderate persistent and severe persistent asthma, respectively, according to the frequency of their symptoms. Addition of spirometric parameter only changed the asthma severity classification in 2.8% of children. Medications were used by 30.6% and 71.3% of children for wheeze in HK and GZ, respectively. In HK, inhaled beta(2)-agonist (73.3% among the drug users) was the commonest medication used followed by inhaled corticosteroid (ICS) (23.3%). In GZ, inhaled beta(2)-agonist was used by 75.4% of children, but use of ICS (26.3%), oral beta(2)-agonist (26.3%), oral theophylline (45.6%), oral ketotifen (36.8%) and oral steroid (35.1%) were also common. ICS was only used by 11.4% of children with persistent asthma. Ten percent and 18.7% of children in HK and GZ, respectively, had emergency department visits, while 16.3% and 11.6% of children in HK and GZ, respectively, had missed school secondary to asthma over the past 1 year.

CONCLUSIONS

Most children in the community had intermittent asthma and addition of lung function to symptoms did not significantly affect classification of asthma severity. Significant morbidity was seen even in this group of children with mostly intermittent and mild persistent asthma.

Environmental determinants associated with the development of asthma in childhood

Asthma is a common chronic respiratory disease, and many epidemiological studies have documented an increasing trend over the past few decades. Comparative studies have shown that asthma is more prevalent in Westernised societies than in rural or developing regions. Environmental factors are likely to be important in explaining such disparities and increasing trends. Although allergen exposure and atopic sensitisation have been thought to be important in the pathogenesis of asthma, recent cross-sectional and longitudinal studies suggest that allergic sensitisation is likely a marker rather than a causative factor for asthma. There is accumulating evidence confirming the role of early exposure to infections in altering the regulation of cytokine production and reduction of subsequent development of atopic disorders. The consistent finding of a lower prevalence of asthma in subjects brought up in a farming environment and the inverse relationship between microbial exposure and asthma symptoms further support the importance of early environmental exposure affecting the risk of subsequent development of asthma. Confirmation of the pathogenetic role of these environmental determinants may allow us to develop primary preventive strategies against the development of asthma and related atopic diseases.

Nitric oxide synthase polymorphisms and asthma phenotypes in Chinese children

BACKGROUND

Nitric oxide (NO) is a key factor for balancing T-helper type 1/T-helper type 2 immunity. Single nucleotide polymorphisms (SNPs) in nitric oxide synthase (NOS) genes have been associated with atopy and exhaled NO concentrations in Caucasians. We investigated the association between asthma traits and genetic polymorphisms in neuronal NO synthase (NOS1) and endothelial NO synthase (NOS3) in Chinese children.

METHODS

Asthmatic children between 5 and 18 years of age and non-allergic controls were recruited. Plasma total IgE was measured by microparticle immunoassay, whereas allergen-specific IgEs were measured by fluorescent enzyme immunoassay. Fractional exhaled NO concentration (FeNO) was measured by a chemiluminescence analyser. NOS1 C5266T and NOS3 G894T were genotyped by restriction fragment length polymorphism, and (AAT)n polymorphism in intron 20 of NOS1 was determined by GeneScan analysis.

RESULTS

The mean (SD) ages of 295 asthmatics and 174 controls were 11.1 (3.8) years and 11.6 (4.0) years, respectively (P=0.162). NOS1 C5266T and NOS3 G894T were not associated with asthma, atopy or FeNO. However, significantly more subjects with T/T in NOS1 C5266T had increased plasma total IgE as compared with those with C/T or C/C (P=0.017). This SNP was also associated with sensitization to Dermatophagoides pteronyssinus (P=0.049). Among asthmatic patients, log-transformed plasma total IgE levels were significantly higher among those homozygous for 5266T of NOS1 [mean (SD): 2.84 (0.44) for T/T, 2.68 (0.42) for C/T, 2.59 (0.69) for C/C; P=0.021]. This study found a significant inter-ethnic difference in the allele frequencies of AAT repeats, and this polymorphism was associated with high plasma total IgE levels (P=0.044) but not FeNO (P=0.158). NOS3 G894T was not associated with any asthma or atopy phenotype.

CONCLUSIONS

NOS1 C5266T and AAT repeats affect plasma IgE concentrations in Chinese children. On the other hand, neither NOS1 nor NOS3 SNP was associated with FeNO or the risk of having asthma.

High levels and gender difference of exhaled nitric oxide in Chinese schoolchildren

BACKGROUND

Exhaled nitric oxide (eNO) may represent a useful noninvasive marker of airway inflammation, but data on the reference population values in schoolchildren are limited. No reference eNO study in Asian children has been published.

METHODS

Levels of eNO in a sample of 531 schoolchildren aged 11-18 years recruited from five schools (three international schools) in Hong Kong were measured online by a chemiluminescence analyser according to ERS/ATS standard. Each student also completed an International Study of Asthma and Allergic disease in Childhood questionnaire.

RESULTS

Among the children without a physician's diagnosis of asthma or symptoms of wheeze, rhinitis and eczema, there were 258 Chinese and 33 Caucasians. In control Chinese children, the eNO level (median: interquantile range) was significantly higher (P<0.001) in males (17.0 parts per billion (p.p.b.); 10.7-36.6) than in females (10.8 p.p.b.; 7.8-17.6). When compared with Caucasian control males (11.6 p.p.b.; 8.2-19.3) and females (9.1 p.p.b.; 7.5-11.9), the Chinese children had significantly higher eNO levels for both males (P=0.011) and females (P=0.037). For Chinese asthmatic males, the median eNO (interquartile range) was 39.8 p.p.b. (12.5-73.8), and for asthmatic females, 18.0 (9.6-56.3). After controlling for sex in Chinese controls, eNO did not have any significant correlation with height, weight and body mass index or body surface area.

CONCLUSIONS

This study demonstrates a gender difference of eNO level in healthy Chinese schoolchildren. When compared with Caucasians, Chinese children have significantly higher eNO levels.

Clinical and atopic parameters and airway inflammatory markers in childhood asthma: a factor analysis

BACKGROUND

Recent studies have repeatedly shown weak correlations among lung function parameters, atopy, exhaled nitric oxide level (Feno), and airway inflammatory markers, suggesting that they are non-overlapping characteristics of asthma in adults. A study was undertaken to determine, using factor analysis, whether the above features represent separate dimensions of childhood asthma.

METHODS

Clinically stable asthmatic patients aged 7-18 years underwent spirometric testing, methacholine bronchial challenge, blood sampling for atopy markers and chemokine levels (macrophage derived chemokine (MDC), thymus and activation regulated chemokine (TARC), and eotaxin), Feno, and chemokines (MDC and eotaxin) and leukotriene B(4) measurements in exhaled breath condensate (EBC).

RESULTS

The mean (SD) forced expiratory volume in 1 second (FEV1) and Feno of 92 patients were 92.1 (15.9)% predicted and 87.3 (65.7) ppb, respectively. 59% of patients received inhaled corticosteroids. Factor analysis selected four different factors, explaining 55.5% of total variance. The Kaiser-Meyer-Olkin measure of sampling adequacy was 0.587. Plasma total and specific IgE levels, peripheral blood eosinophil percentage, and Feno loaded on factor 1; plasma TARC and MDC concentrations on factor 2; MDC, eotaxin and leukotriene B4 concentrations in EBC on factor 3; and plasma eotaxin concentration together with clinical indices including body mass index and disease severity score loaded on factor 4. Post hoc factor analyses revealed similar results when outliers were excluded.

CONCLUSIONS

The results suggest that atopy related indices and airway inflammation are separate dimensions in the assessment of childhood asthma, and inflammatory markers in peripheral blood and EBC are non-overlapping factors of asthma.

RANTES G-401A polymorphism is associated with allergen sensitization and FEV1 in Chinese children

G-401A polymorphism in RANTES promoter was associated with near-fatal asthma and atopic dermatitis in children. We studied whether gain-of-function mutations in RANTES gene were associated with asthma and atopy-related traits in Chinese children. Plasma total and aeroallergen-specific IgE concentrations were measured using micro-particle immunoassay and fluorescent enzyme immunoassay, respectively. Restriction fragment length polymorphism was used to genotype RANTES G-401A and C-28G. One hundred and twenty-nine asthmatic children and 66 controls were recruited. Their mean logarithmic plasma total IgE concentrations were 2.53 and 1.98, respectively (P<0.0001). RANTES G-401A was not associated with physician-diagnosed asthma (P = 0.408). However, RANTES G-401A allele was significantly associated with IgE sensitization to cat (odds ratio 2.35; 95% CI 1.15-4.77; P = 0.010). Those homozygous for -401A had higher plasma cat-specific IgE levels (P = 0.034). Subjects having -401A were also more likely to have mold-specific IgE (odds ratio 3.82; 95% CI 1.24-12.14; P = 0.007). On spirometry, those with -401A/ A had lower forced expiratory volume in 1-s (FEV1; P = 0.044). RANTES C-28G was not associated with any outcome in this study. In conclusion, the gain-of-function mutation at -401 of RANTES promoter is associated with sensitization to cat and mold allergens and FEV1 in Chinese children.

Declining asthma prevalence in Hong Kong Chinese schoolchildren

BACKGROUND

Many studies have reported an increase in the prevalence of asthma and related atopic disorders. The lack of standardized methodologies and 'objective' measurements make reliable comparison and monitoring of trends of asthma very difficult.

METHODS

In this study, a total of 3321 schoolchildren aged 13-14 years were recruited for study using the Phase III Protocol of the International Study of Asthma and Allergic disease in Childhood (ISAAC). The results were compared with those obtained in the Phase I ISAAC study (1994-95), which used the identical and validated core questionnaires.

RESULTS

The prevalence rates of physicians' diagnosis of asthma were similar in the two surveys (11.2% and 10.2%), but the prevalence rates of wheeze (written questionnaire) in the past year have decreased from 12.4% in 1994-95 to 8.7% in 2002 (P<0.001). For the video questionnaire, all asthmatic symptoms in the preceding 12 months were significantly lower in 2002 when compared with those in 1994-95. Among the subjects with diagnosed asthma, the prevalence rates of wheeze in the past 12 months (written questionnaire) has decreased from 39.1% to 27.6% (P<0.001). The prevalence rates of having wheezing attack at least once per month (video questionnaire) has decreased from 10.5% to 5.6% (P=0.013).

CONCLUSION

Using the same standardized and validated ISAAC questionnaire, the prevalence rates of asthma symptoms in Hong Kong Chinese schoolchildren have decreased since 1994. The exact reasons for such trend remain to be explored.

Increased macrophage-derived chemokine in exhaled breath condensate and plasma from children with asthma

BACKGROUND

Type 2 helper T lymphocyte-specific chemokines including macrophage-derived chemokine (MDC), thymus and activation-regulated chemokine (TARC) and eotaxin are important mediators for allergic airway inflammation.

OBJECTIVE

We investigated whether these chemokines can be detected in exhaled breath condensate (EBC) and their relation to childhood asthma.

METHODS

Asthmatics recruited from paediatric clinics of a university teaching hospital were classified into intermittent asthma (IA) and persistent asthma (PA) according to Global Initiative for Asthma guidelines. EBC was collected by a disposable collection kit, whereas fractional exhaled nitric oxide (FENO) was measured by a chemiluminescence analyser. Concentrations of MDC, TARC and eotaxin in both EBC and plasma were measured using sandwich enzyme immunoassay. The intra-subject reproducibility of exhaled chemokine measurements was determined by co-efficients of variation (CV).

RESULTS

Forty-eight patients with PA, 36 children with IA and 18 controls were recruited. MDC and eotaxin were present in EBC from nearly all subjects, whereas TARC could be measured in EBC from 33 (32%) subjects only. The median MDC concentration in EBC was higher in PA (117 pg/mL) as compared with IA (106 pg/mL) and controls (105 pg/mL; P=0.003 for both). The median plasma MDC concentration in PA (648 pg/mL) was also higher than that in IA (520 pg/mL; P=0.002) and controls (490 pg/mL; P=0.008). The median plasma TARC concentration was also increased in PA as compared with IA (72 pg/mL vs. 35 pg/mL; P=0.004). MDC concentrations in EBC were lower in patients with PA who received high-dose inhaled corticosteroid (P=0.005). FENO was significantly higher in asthmatics than controls (P<0.0001), but it was not associated with chemokines in EBC or plasma. The mean (range) CV for measuring MDC, TARC and eotaxin in EBC (n=6) were 5.5 (2.0-7.2%), 8.8 (3.6-14.4%) and 5.2 (2.8-7.9%), respectively.

CONCLUSIONS

Our results suggest that MDC in EBC and MDC and TARC in plasma are increased in children with PA as compared with IA or control. MDC concentrations in EBC are suppressed in patients on high-dose inhaled corticosteroid treatment.