Acute asthma in children: Relationships among CD14 and CC16 genotypes, plasma levels, and severity

Associations of Serum Clara Cell Protein 16 with Severity and Prognosis in Adults with Community-Acquired Pneumonia

Background

Clara cell protein 16 (CC16) has multiple functions, including antioxidant, anti-inflammatory, and immune regulation properties. Nevertheless, the concrete function of CC16 in adult patients with community-acquired pneumonia (CAP) remained blurred.

Methods

A total of 541 adult patients with CAP were recruited on admission. Peripheral blood specimens, clinical parameters, and demographic characteristics were collected. The concentration of serum CC16 was evaluated through ELISA. The relationships between serum CC16 and clinical parameters were appraised by Spearman or Pearson correlative analyses. The correlations of serum CC16 with severity and prognosis were assessed using linear or logistic regression models.

Results

The level of CC16 was gradually decreased across with the elevated severity scores system of CAP. After treatment, the level of serum CC16 was upregulated. Correlative analyses found that serum CC16 was negatively related to inflammatory cytokines. Additionally, multivariate linear and logistic regression models revealed that serum CC16 was inversely associated with severity scores system. In addition, reduced serum CC16 on admission elevated the risks of vasoactive agent usage, ICU admission, and death during hospitalization. We observed an almost discriminatory ability for severity and death between serum CC16 and severity scores system, and were all obviously elevated compared to routine inflammatory and infectious markers.

Conclusion

There are substantially inverse correlations between serum CC16 level on admission with severity scores and poorly prognostic outcomes, indicating that CC16 is involved in the pathophysiological process of CAP. This study is helpful for establishing the potential application of serum CC16 in risk evaluation and targeted treatment.

LPS binding protein and activation signatures are upregulated during asthma exacerbations in children

Asthma exacerbations in children are associated with respiratory viral infection and atopy, resulting in systemic immune activation and infiltration of immune cells into the airways. The gene networks driving the immune activation and subsequent migration of immune cells into the airways remains incompletely understood. Cellular and molecular profiling of PBMC was employed on paired samples obtained from atopic asthmatic children (n = 19) during acute virus-associated exacerbations and later during convalescence. Systems level analyses were employed to identify coexpression networks and infer the drivers of these networks, and validation was subsequently obtained via independent samples from asthmatic children. During exacerbations, PBMC exhibited significant changes in immune cell abundance and upregulation of complex interlinked networks of coexpressed genes. These were associated with priming of innate immunity, inflammatory and remodelling functions. We identified activation signatures downstream of bacterial LPS, glucocorticoids and TGFB1. We also confirmed that LPS binding protein was upregulated at the protein-level in plasma. Multiple gene networks known to be involved positively or negatively in asthma pathogenesis, are upregulated in circulating PBMC during acute exacerbations, supporting the hypothesis that systemic pre-programming of potentially pathogenic as well as protective functions of circulating immune cells preceeds migration into the airways. Enhanced sensitivity to LPS is likely to modulate the severity of acute asthma exacerbations through exposure to environmental LPS.

Club Cell Secretory Protein in Lung Disease: Emerging Concepts and Potential Therapeutics

Club cell secretory protein (CCSP), also known as secretoglobin 1A1 (gene name SCGB1A1), is one of the most abundant proteins in the lung, primarily produced by club cells of the distal airway epithelium. At baseline, CCSP is found in large concentrations in lung fluid specimens and can also be detected in the blood and urine. Obstructive lung diseases are generally associated with reduced CCSP levels, thought to be due to decreased CCSP production or club cell depletion. Conversely, several restrictive lung diseases have been found to have increased CCSP levels both in the lung and in the circulation, likely related to club cell dysregulation as well as increasedlung permeability. Recent studies demonstrate multiple mechanisms by which CCSP dampens acute and chronic lung inflammation. Given these anti-inflammatory effects, CCSP represents a novel potential therapeutic modality in lung disease.

Viral Induced Effects on a Vulnerable Epithelium; Lessons Learned From Paediatric Asthma and Eosinophilic Oesophagitis

The epithelium is integral to the protection of many different biological systems and for the maintenance of biochemical homeostasis. Emerging evidence suggests that particular children have epithelial vulnerabilities leading to dysregulated barrier function and integrity, that resultantly contributes to disease pathogenesis. These epithelial vulnerabilities likely develop in utero or in early life due to various genetic, epigenetic and environmental factors. Although various epithelia are uniquely structured with specific function, prevalent allergic-type epithelial diseases in children potentially have common or parallel disease processes. These include inflammation and immune response dysregulation stemming from atypical epithelial barrier function and integrity. Two diseases where aetiology and pathogenesis are potentially linked to epithelial vulnerabilities include Paediatric Asthma and Eosinophilic Oesophagitis (EoE). For example, rhinovirus C (RV-C) is a known risk factor for paediatric asthma development and is known to disrupt respiratory epithelial barrier function causing acute inflammation. In addition, EoE, a prevalent atopic condition of the oesophageal epithelium, is characterised by similar innate immune and epithelial responses to viral injury. This review examines the current literature and identifies the gaps in the field defining viral-induced effects on a vulnerable respiratory epithelium and resulting chronic inflammation, drawing from knowledge generated in acute wheezing illness, paediatric asthma and EoE. Besides highlighting the importance of epithelial structure and barrier function in allergic disease pathogenesis regardless of specific epithelial sub-types, this review focuses on the importance of examining other parallel allergic-type disease processes that may uncover commonalities driving disease pathogenesis. This in turn may be beneficial in the development of common therapeutics for current clinical management and disease prevention in the future.

CC16 as a Marker of COE-Induced the Early Change of Blood Composition of Coke Oven Workers: A Case Control Study

OBJECTIVE

This project aims to enhance the occupational health insurance for coke oven workers.

METHODS

A total of 136 coke oven emissions workers and 61 oxygen plant workers were recruited to receive physical examinations. The coke oven emissions concentration at the workplace was measured by weighing method. The CC16 concentration was detected by enzyme-linked immunosorbent assay.

RESULTS

Logistic regression analysis revealed that exposure to coke oven emissions was correlated with CC16. Correlation analysis revealed that CC16 was related to some physical examination indicators. Multivariate general linear models showed that CC16 was indeed positively correlated with albumin after adjusting for confounding factors.

CONCLUSIONS

Coke oven emissions affected multiple tissues and multiple systems. The blood system might be the earliest system affected and could be detected by the CC16 protein concentration.

Vernal keratoconjunctivitis activity induces decrease of ocular surface CD14, TLR-4 and TLR-9 expression

PURPOSE

CD14 is involved in the modulation of immune reaction via toll-like receptors (TLR) and may influence the development of allergic diseases. The role of CD14 in vernal keratoconjunctivitis (VKC) has not yet been investigated. The aim of this study is to evaluate changes of tear soluble sCD14 and conjunctival CD14, TLR-4 and 9 expression in patients with VKC in the active and quiescent phases.

METHODS

Eighteen patients with VKC during active inflammation (group A, N = 9), in the quiescent phase (group Q, N = 5) and after recovery (group R, N = 4) and 10 healthy subjects were included. Expression of sCD14 in tears and of CD14, TLR-4, and TLR-9 by conjunctival epithelium were evaluated by Western Blot in all groups.

RESULTS

Expression of tear sCD14 and of conjunctival CD14, TLR-4, and TLR-9 was significantly decreased in group A when compared with healthy subjects and with VKC group Q and R. Lower expression of sCD14, CD14, TLR-4, and TLR-9 were significantly correlated with the severity of papillary reaction, while the lower sCD14 was correlated with severity of conjunctival hyperemia.

CONCLUSIONS

Tear sCD14, and conjunctival CD14, TLR4, and TLR-9 decreased during ocular surface inflammatory reaction in patients with VKC. CD14 and TLRs ocular surface evaluation may represent biomarkers of VKC activity and novel therapeutic target.

Cellular and Molecular Pathways of COVID-19 and Potential Points of Therapeutic Intervention

With the objective of linking early findings relating to the novel SARS-CoV-2 coronavirus with potentially informative findings from prior research literature and to promote investigation toward therapeutic response, a coherent cellular and molecular pathway is proposed for COVID-19. The pathway is consistent with a broad range of observed clinical features and biological markers and captures key mediators of pathophysiology. In this proposed pathway, membrane fusion and cytoplasmic entry of SARS-CoV-2 virus via ACE2 and TMPRSS2-expressing respiratory epithelial cells, including pulmonary type-II pneumocytes, provoke an initial immune response featuring inflammatory cytokine production coupled with a weak interferon response, particularly in IFN-λ-dependent epithelial defense. Differentiation of non-classic pathogenic T-cells and pro-inflammatory intermediate monocytes contributes to a skewed inflammatory profile, mediated by membrane-bound immune receptor subtypes (e.g., FcγRIIA) and downstream signaling pathways (e.g., NF-κB p65 and p38 MAPK), followed by chemotactic infiltration of monocyte-derived macrophages and neutrophils into lung tissue. Endothelial barrier degradation and capillary leakage contribute to alveolar cell damage. Inflammatory cytokine release, delayed neutrophil apoptosis, and NETosis contribute to pulmonary thrombosis and cytokine storm. These mechanisms are concordant with observed clinical markers in COVID-19, including high expression of inflammatory cytokines on the TNF-α/IL-6 axis, elevated neutrophil-to-lymphocyte ratio (NLR), diffuse alveolar damage via cell apoptosis in respiratory epithelia and vascular endothelia, elevated lactate dehydrogenase (LDH) and CRP, high production of neutrophil extracellular traps (NETs), depressed platelet count, and thrombosis. Although certain elements are likely to be revised as new findings emerge, the proposed pathway suggests multiple points of investigation for potential therapeutic interventions. Initial candidate interventions include prophylaxis to augment epithelial defense (e.g., AT1 receptor blockade, type III and type I interferons, melatonin, calcitriol, camostat, and lopinavir) and to reduce viral load (e.g., remdesivir, ivermectin, emetine, Abelson kinase inhibitors, dopamine D2 antagonists, and selective estrogen receptor modulators). Additional interventions focus on tempering inflammatory signaling and injury (e.g., dexamethasone, doxycycline, Ang1-7, estradiol, alpha blockers, and DHA/EPA, pasireotide), as well as inhibitors targeted toward molecular mediators of the maladaptive COVID-19 immune response (e.g., IL-6, TNF-α, IL-17, JAK, and CDK9).

Vitamin D receptor polymorphisms are associated with severity of wheezing illnesses and asthma exacerbations in children

Single nucleotide polymorphisms (SNPs) of the vitamin D receptor (VDR) gene have shown linkage and association with asthma development in multiple cohort studies. However, the majority of investigations have focused on asthma phenotypes in cohorts with stable disease. We investigated the relationship between VDR SNPs and the frequency and severity of acute episodes of wheeze/asthma in a cohort of Australian children, as the ability to identify children at risk of more severe exacerbations could lead to personalized and improved genotype-specific treatment pathways. We successfully genotyped five SNPs of the VDR gene (rs2525046, rs9729, rs1544410 (BsmI), rs22239179, and rs2228570 (FokI)) in 657 children presenting to a tertiary children's hospital with acute asthma, bronchiolitis, or a wheezing illness. The relationships between VDR SNPs and exacerbation severity scores, β₂-agonist use, and frequency of respiratory exacerbations were analysed using multiple regression. The rs2525046 (FokI) CT genotype was associated with higher VDR mRNA intensity levels (p = 0.007) compared to the CC genotype. A trend towards significance (p=0.056) was identified between the rs2525046 TT genotype and higher VDR mRNA intensity levels compared to the CC genotype. Children with rs2228570 AA genotype had higher exacerbation severity scores (p=0.001) and poorer β₂-agonist treatment response (doses at 6 h: p = 0.009 and 12 h: p=0.033) compared to those with the GG genotype. Children with rs1544410 (BsmI) TT genotype had lower exacerbation severity scores (p = 0.005) compared to those with the CC genotype. Children with rs2228570 GA genotype presented to and/or were admitted to hospital more times since birth with respiratory (p = 0.011) and wheezing (p = 0.021) illnesses than children with the GG genotype. No associations were identified between rs9729, rs2525046 and r2239179 polymorphisms and acute wheezing/asthma variables. These findings suggest that genetic variants at the VDR locus may play a role in acute wheeze/asthma severity in children.

Urinary club cell protein 16 (CC16): Utility of its assay during acute bronchiolitis

Acute bronchiolitis is responsible for high morbidity in infants. Club cell protein 16 kDa (CC16) is a major pneumoprotein secreted by club cells of the bronchial epithelium and eliminated by the renal pathway. CC16 seems to be a biomarker of epithelial damage in asthma. However, its value as a marker of acute bronchiolitis severity and later recurrent wheezing are uncertain, especially the value of its urinary assay for this purpose. A prospective, observational, analytical study was conducted at Clermont-Ferrand University Hospital to correlate serum CC16 level with clinical severity of bronchiolitis in hospitalized infants aged less than 1 year. We analyzed correlations between serum and urinary CC16, CC16 levels and Wainwright score, immediate morbidity due to bronchiolitis, causal viruses, and recurrent wheezing 1 year after inclusion. In 166 infants, serum CC16 did not correlate with acute bronchiolitis severity (P = .49), but urinary CC16 did (P < .001). In multivariate analysis, urinary CC16 correlated mainly with urinary retinol binding protein (RBP; r = 0.70; P < .001). The logCC16u/logRBPu ratio correlated significantly with severity (P = .02). CC16 levels were not correlated with recurrent wheezing at 1 year. Urinary CC16 could be a useful biomarker in acute bronchiolitis for specific indications. This noninvasive assay would be particularly useful in the young infant population. Several factors must be taken into account in its interpretation, mainly tubular function. Further studies are needed to assess these factors.

Association of plasma soluble CD14 level with asthma severity in adults: a case control study in China

Background

Soluble CD14 (sCD14) shedding from CD14 could regulate T lymphocyte activation and function, which has implicated in the pathogenesis of bronchial asthma. The level of sCD14 expression is obviously increased in asthmatic patients during acute asthma attacks. The objective of this study was to investigate the association between plasma sCD14 level and asthma severity in adults.

Methods

The plasma sCD14 level in asthma patients (n = 910) and healthy controls (n = 881) was quantified by commercially available enzyme-linked immunosorbent assay (ELISA) kits. The asthma cases were subdivided into intermittent asthma (n = 537), mild (n = 246), moderate (n = 96) and severe (n = 31) persistent asthma patients. Association between plasma sCD14 level and asthma severity, lung function parameters as well as asthma symptoms and signs in adults were performed using multivariate logistic regression models.

Results

We observed significant relationships of plasma sCD14 level with asthma severity, lung function parameters as well as asthma symptoms and signs in adults. After adjusting for multiple potential confounders, each one-unit increase in log sCD14 was significantly associated with 67, 82, 79 and 85% reduced ORs for intermittent asthma, mild, moderate and severe persistent asthma, respectively (all P < 0.0001). Compared with the participants of FEV₁/FVC ≥75%, each one-unit increase in log sCD14 was significantly associated with a 37% decreased OR of FEV₁/FVC < 75% (P < 0.0001). However, the adjusted odds ratios (ORs) of severe dyspnea, wheeze and cyanosis in asthma patients were 1.88, 1.46 and 2.20 for each one-unit increase in log sCD14, respectively. In addition, compared with health controls, the adjusted area under the curve (AUC) of sCD14 was 0.814 at a cut-off points of 0.53, and the sensitivity and specificity were 71.0 and 76.8% for predicting asthma in adults. And the adjusted AUC of sCD14 reached 0.786, 0.847, 0.887 and 0.917 in predicting intermittent asthma, mild, moderate and severe persistent asthma, respectively.

Conclusions

Our results indicated that plasma sCD14 level is negatively associated with asthma severity, suggesting a protective role for sCD14 in the development of asthma in adults. And plasma sCD14 level might be a potential biomarker in prediction of asthma severity in adults.

Electronic supplementary material

The online version of this article (10.1186/s12931-019-0987-0) contains supplementary material, which is available to authorized users.

The CD14 (-159 C/T) SNP is associated with sCD14 levels and allergic asthma, but not with CD14 expression on monocytes

LPS-ligation to CD14/TLR-4 on monocytes/macrophages triggers the production of IL-12-family cytokines. IL12/18 promote TH₁-differentiation, counteracting the TH₂-driven asthma. Therefore, CD14 modulation could alter the TH₂-differentiation and should be taken into account when studying asthma. To analyse the alteration in CD14 levels and its association with CD14 (−159 C/T) SNP (rs2569190) in Caucasian adults with stable allergic asthma, we performed a cross-sectional study (277 healthy subjects vs. 277 patients) where clinical parameters, CD14 values and the CD14 (−159 C/T) SNP were studied. Apart from typical biomarkers, we found an increment of neuron-specific enolase (NSE) in allergic asthma, probably linked to monocyte activity. Indeed, we evidenced increased monocyte numbers, but lower CD14 expression and normalised sCD14 values in patients. Moreover, we noticed an association of the T allele (P = 0.0162) and TT genotype (P = 0.0196) of the CD14 SNP with a decreased risk of allergic asthma and augmented sCD14 levels. In conclusion, monocyte CD14 expression and normalized sCD14 values were reduced in stable state asthmatics, and this could be related to the presence of an expanded CD14^low monocyte subset. This study also demonstrates that the CD14 (−159 C/T) polymorphism is a risk factor for moderate-severe allergic asthma in adult Caucasians.

Urinary polycyclic aromatic hydrocarbon metabolites, Club cell secretory protein and lung function

BACKGROUND

Exposure to polycyclic aromatic hydrocarbons (PAHs) has been associated with lung function decline. However, the underlying mechanisms for the association remain unclear.

OBJECTIVES

To explore potential role of a lung epithelial biomarker, Club cell secretory protein (CC16), in associations between PAH exposures and lung function decline.

METHODS

We investigated 3384 adults from the Wuhan-Zhuhai cohort, and followed up at three years after first examination. Linear mixed models was used to quantify dose-response relationships between urinary monohydroxylated PAH metabolites (OH-PAHs) and lung function, as well as OH-PAHs and plasma CC16. Mediation analysis was conducted to investigate role of CC16 in the association between OH-PAHs and lung function. We also estimated the relationships between OH-PAHs and lung function change in three years among participants with different levels of CC16.

RESULTS

Each 1-unit increase of log-transformed total urinary high and low molecular weight OH-PAHs (∑HMW OH-PAH and ∑LMW OH-PAHs) were associated with a 22.59 and 25.25ml reduction of FEV₁ respectively, while∑HMW OH-PAH was associated with a 30.38ml reduction of FVC. Moreover, these negative associations between OH-PAHs and lung function levels were significant only among low CC16 group (<15.83ng/ml). CC16 concentration decreased monotonically with increased high molecular weight OH-PAHs (∑HMW OH-PAHs) when ∑HMW OH-PAH concentration was over 0.67μg/mmol Cr. CC16 mediated 22.13% of the association between ∑HMW OH-PAH and FVC among individuals with higher ∑HMW OH-PAH. After three years of follow-up, subjects with low level of plasma CC16 had a significant decline of FVC when exposed to high level of ∑HMW OH-PAH.

CONCLUSIONS

CC16 play an important role in the association between high molecular weight PAHs and FVC. Individuals with low plasma CC16 level might suffer a decline in lung function when exposed to high level of high molecular weight PAHs.

No simple answers for the Finnish and Russian Karelia allergy contrast: Methylation of CD14 gene

BACKGROUND

Finnish and Russian Karelian children have a highly contrasting occurrence of asthma and allergy. In these two environments, we studied associations between total serum immunoglobulin E (IgE) with methylation levels in cluster of differentiation 14 (CD14).

METHODS

Five hundred Finnish and Russian Karelian children were included in four groups: Finnish children with high IgE (n = 126) and low IgE (n = 124) as well as Russian children with high IgE (n = 125) and low IgE (n = 125). DNA was extracted from whole blood cells and pyrosequenced. Three CpG sites were selected in the promoter region of CD14.

RESULTS

Methylation levels in two of the three CpG sites were higher in the Finnish compared to Russian Karelian children. In the promoter area of CD14, the Finnish compared to Russian children with low IgE had a significant (p < 0.0001) increase in methylation levels at the Amp5Site 2. Likewise, the Finnish compared to Russian children with high IgE had a significant (p = 0.003) increase in methylation levels at the Amp5Site 3. In Russian children with low vs. high IgE, there were significant differences in methylation levels, but this was not the case on the Finnish side. In the regression analysis, adding the methylation variation of CD14 to the model did not explain the higher asthma and allergy risk in the Finnish children.

CONCLUSIONS

The methylation levels in the promoter region of CD14 gene were higher in the Finnish compared to Russian Karelian children. However, the methylation variation of this candidate gene did not explain the asthma and allergy contrast between these two areas.

Cord Blood Soluble CD14 Predicts Wheeze and Prolonged Cough in Young Children: The PATCH Study

BACKGROUND

Soluble cluster of differentiation 14 (sCD14) plays a role in the development and manifestation of atopic symptoms, although the results of previous studies have been inconclusive. The aim of this study is to evaluate the practical use of sCD14 as a predictive biomarker of allergy in young children.

METHODS

Children aged 0-1 year from a birth cohort in the Prediction of Allergies in Taiwanese Children (PATCH) study were enrolled. Cord blood sCD14 concentrations were measured. Pediatrician evaluation and questionnaire interviews were performed periodically until 1 year of age to determine the children's allergic and respiratory symptoms.

RESULTS

Two hundred and six 1-year-old subjects were enrolled. Wheeze was positively associated with cord blood sCD14, a family member with asthma and parental smoking. Prolonged cough was associated with cord blood sCD14, older maternal age and more siblings. In the multivariate logistic regression analysis, cord blood sCD14 was the only independent predictive biomarker for wheeze and prolonged cough by 1 year of age. Every 100-ng/ml increase in cord blood sCD14 resulted in a 1.56-fold higher risk of developing wheeze and a 1.62-fold higher risk of prolonged cough in children by 1 year of age.

CONCLUSIONS

Cord blood sCD14 may be a useful biomarker for predicting infant wheeze and prolonged cough by 1 year of age.

Recurrent rhinovirus detections in children following a rhinovirus-induced wheezing exacerbation: A retrospective study

INTRODUCTION

It is unclear if children with a rhinovirus (RV)-induced wheezing exacerbation are more susceptible to viruses longitudinally, and whether a parental history of asthma and/or allergy impacts their susceptibility. The objective of this study was to determine if RV, RV-A and RV-C related wheezing exacerbations in children were associated with prior or subsequent viral detections and investigate the role of parental history of asthma and allergy.

MATERIALS AND METHODS

Children presenting to hospital with acute wheeze were prospectively recruited and tested for respiratory viruses. Data on viruses detected in other respiratory samples (May 1997 to December 2012) were collected from hospital microbiology records and additional RV testing was performed on stored hospital respiratory samples (September 2009 to December 2012). A positive parental history was defined as either parent with self-reported asthma and/or allergy.

RESULTS

At recruitment, RV was detected in 69.2% of samples from children with an acute wheezing episode (n=373, 0-16 years of age), with RV-C the most common virus (65.5%). Children with a history of parental asthma and/or allergy and RV at recruitment had a 14-fold increased incidence rate ratio (IRR) of subsequent RV detection (IRR 14.0, 95% CI 1.9-104.1; p=0.01) compared with children without RV at recruitment. Children without this parental history had a reduced incident rate ratio for samples assessed during this time (IRR 0.5, 95% CI 0.3-0.9; p=0.03).

CONCLUSION

Children with a parental history of asthma and/or allergy may become more susceptible to recurrent symptomatic RV infections.

The effect of CD14 and TLR4 gene polymorphisms on asthma phenotypes in adult Turkish asthma patients: a genetic study

BACKGROUND

Endotoxins stimulate T helper 1 cell maturation and send a negative signal to T helper 2 polarisation. This causes a decrease IgE levels and prevents atopy (Hygiene hypothesis). It is shown that this response is under genetic control by polymorphisms in CD14 and TLR4 genes in some researchs. We aimed to investigate the effects of genetic variants of CD14 (-) and TLR4 (Asp299Gly, Thr399Ile) genes on asthma phenotypes in adults with asthma.

METHODS

Asthma patients (n = 131) and healthy control cases (n = 75) were included in the study. Relations between CD14 C-159 T, TLR4 299 and TLR4 399 genotypes and duration of asthma history of allergic rhinitis-dermatitis, total IgE, eosinophil, skin prick test, forced expiratory volume 1 (FEV1) and severity of disease were evaluated. Real time PCR (RT-PCR) was used for genotyping.

RESULTS

For CD14-159, presence of the C allele (CC + CT) was more frequent among those with low median log (logarithm) IgE levels, but no statistically significant difference in all asthma group (p = 0.09). C allele was significantly correlated with low total IgE levels and T allele with high total IgE levels in atopics (p = 0.04). CC + CT genotype was more frequent in moderate and severe asthma group in atopics (p = 0.049). TLR4 299 and TLR4 399 genotypes and asthma phenotypes were not found to be significantly correlated (p > 0.05).

CONCLUSIONS

Total IgE levels were found to be low among patients with the CC + CT genotype, and high among patients with the TT genotype contrary to the results of many other studies, which is therefore an important finding. Another important finding was that the C allele is a risk factor for moderate and severe asthma.

Epistatic effects of multiple receptor genes on pathophysiology of asthma - its limits and potential for clinical application

To date, genome-wide association studies (GWAS) permit a comprehensive scan of the genome in an unbiased manner, with high sensitivity, and thereby have the potential to identify candidate genes for the prevalence or development of multifactorial diseases such as bronchial asthma. However, most studies have only managed to explain a small additional percentage of hereditability estimates, and often fail to show consistent results among studies despite large sample sizes. Epistasis is defined as the interaction between multiple different genes affecting phenotypes. By applying epistatic analysis to clinical genetic research, we can analyze interactions among more than 2 molecules (genes) considering the whole system of the human body, illuminating dynamic molecular mechanisms. An increasing number of genetic studies have investigated epistatic effects on the risk for development of asthma. The present review highlights a concept of epistasis to overcome traditional genetic studies in humans and provides an update of evidence on epistatic effects on asthma. Furthermore, we review concerns regarding recent trends in epistatic analyses from the perspective of clinical physicians. These concerns include biological plausibility of genes identified by computational statistics, and definition of the diagnostic label of 'physician-diagnosed asthma'. In terms of these issues, further application of epistatic analysis will prompt identification of susceptibility of diseases and lead to the development of a new generation of pharmacological strategies to treat asthma.

Human rhinovirus species C infection in young children with acute wheeze is associated with increased acute respiratory hospital admissions

RATIONALE

Human rhinovirus species C (HRV-C) is the most common cause of acute wheezing exacerbations in young children presenting to hospital, but its impact on subsequent respiratory illnesses has not been defined.

OBJECTIVES

To determine whether acute wheezing exacerbations due to HRV-C are associated with increased hospital attendances due to acute respiratory illnesses (ARIs).

METHODS

Clinical information and nasal samples were collected prospectively from 197 children less than 5 years of age, presenting to hospital with an acute wheezing episode. Information on hospital attendances with an ARI before and after recruitment was subsequently obtained.

MEASUREMENTS AND MAIN RESULTS

HRV was the most common virus identified at recruitment (n = 135 [68.5%]). From the 120 (88.9%) samples that underwent typing, HRV-C was the most common HRV species identified, present in 81 (67.5%) samples. Children with an HRV-related wheezing illness had an increased risk of readmission with an ARI (relative risk, 3.44; 95% confidence interval, 1.17-10.17; P = 0.03) compared with those infected with any other virus. HRV-C, compared with any other virus, was associated with an increased risk of a respiratory hospital admission before (49.4% vs. 27.3%, respectively; P = 0.004) and within 12 months (34.6% vs. 17.0%; P = 0.01) of recruitment. Risk for subsequent ARI admissions was further increased in atopic subjects (relative risk, 6.82; 95% confidence interval, 2.16-21.55; P = 0.001). Admission risks were not increased for other HRV species.

CONCLUSIONS

HRV-C-related wheezing illnesses were associated with an increased risk of prior and subsequent hospital respiratory admissions. These associations are consistent with HRV-C causing recurrent severe wheezing illnesses in children who are more susceptible to ARIs.

CD14 tobacco gene-environment interaction in atopic children

Studying gene-environment interactions may elucidate the complex origins of atopic diseases. The aim of this study was to evaluate the association of CD14 polymorphisms and atopy in Egyptian children and to study whether atopy is influenced by CD14 interaction with tobacco smoke exposure. CD14 -159 C/T and CD14 -550 C/T were genotyped in 500 asthmaic children, 150 allergic rhinitis children and 150 controls. We found that CD14 -159T allele, CD14 -550T allele and CD14 -159T/-550T haplotype were significantly associated with atopic asthma and allergic rhinitis groups. CD14 -159 TT and CD14 -550 TT genotypes associated with elevated IgE levels in children exposed to tobacco smoke. The TT genotype of CD14 -159 C/T and CD14 -550 C/T was associated with higher serum levels of sCD14. The present study indicated that CD14 gene polymorphisms may contribute to susceptibility to atopy in Egyptian children and influenced with tobacco smoke exposure.

Role of biomarkers in understanding and treating children with asthma: towards personalized care

Asthma is one of the most common chronic diseases affecting children. Despite publicized expert panels on asthma management and the availability of high-potency inhaled corticosteroids, asthma continues to pose an enormous burden on quality of life for children. Research into the genetic and molecular origins of asthma are starting to show how distinct disease entities exist within the syndrome of "asthma". Biomarkers can be used to diagnose underlying molecular mechanisms that can predict the natural course of disease or likely response to drug treatment. The progress of personalized medicine in the care of children with asthma is still in its infancy. We are not yet able to apply stratified asthma treatments based on molecular phenotypes, although that time may be fast approaching. This review discusses some of the recent advances in asthma genetics and the use of current biomarkers that can help guide improved treatment. For example, the fraction of expired nitric oxide and serum Immunoglobulin E (IgE) (including allergen-specific IgE), when evaluated in the context of recurrent asthma symptoms, are general predictors of allergic airway inflammation. Biomarker assays for secondhand tobacco smoke exposure and cysteinyl leukotrienes are both promising areas of study that can help personalize management, not just for pharmacologic management, but also education and prevention efforts.

A systematic review of CD14 and toll-like receptors in relation to asthma in Caucasian children

The aetiology of childhood asthma is complex. An early dysfunction in the immunological development of the innate immune system in combination with environmental factors possibly triggers asthma. CD14 and toll-like receptors are important components of the innate immune system. The aim of this systematic review was to obtain a better insight into the relation between CD14 and toll-like receptors and childhood asthma in Caucasians. We searched PubMed and EMBASE for relevant articles. In total, 44 articles were included. The quality of the selected studies was independently assessed by the first two authors using the Newcastle-Ottawa quality assessment scale. Toll-like receptor 2, toll-like receptor 6, toll-like receptor 9, and toll-like receptor 10 appear to have some association with childhood asthma in Caucasians. The evidence for a relation of CD14 with childhood asthma is limited. In conclusion, there is no convincing evidence yet for a role of CD14 and toll-like receptors in relation to childhood asthma. Future studies should include haplotype analysis and take environmental factors into account to further clarify the role of CD14 and toll-like receptors on childhood asthma.

Symptomatic viral infection is associated with impaired response to treatment in children with acute asthma

OBJECTIVE

To examine the influence of viral respiratory infection (VRI) on treatment response in acute asthma in children.

STUDY DESIGN

A total of 218 children (mean age, 6.6 years) with acute asthma were recruited. Symptoms were recorded, an asthma severity score was determined, and whenever possible, a per-nasal aspirate was obtained for detection of viruses. Each child's response to inhaled β(2)-agonists was assessed after 6, 12, and 24 hours.

RESULTS

The 168 children with VRI symptoms received more treatment with inhaled β(2)-agonists after 6 hours (P = .010), 12 hours (P = .002), and 24 hours (P = .0005) compared with the 50 children without such symptoms. Asthma severity did not differ between the 2 groups. A per-nasal aspirate was obtained from 77% of the children. The most frequently identified virus was rhinovirus (61.4%). Among children with symptoms of a VRI, those with rhinovirus had an impaired response to β(2)-agonists at 6 hours (P = .032).

CONCLUSION

Children with acute asthma and symptoms of VRI respond less effectively to β(2)-agonists after 6, 12, or 24 hours and thus may benefit from more intense therapy and monitoring.

Comparable effect of conventional ventilation versus early high-frequency oscillation on serum CC16 and IL-6 levels in preterm neonates

OBJECTIVE

Clara cell 16 kD protein (CC16) and interleukin (IL)-6 have been used as peripheral blood biomarkers of alveolar leakage and inflammation, respectively. Thus, their measurement in the bloodstream could be used to assess ventilator-induced lung injury. The objective of this study was to evaluate the effect of optimized synchronized intermittent mandatory ventilation (SIMV) and high-frequency oscillatory ventilation (HFOV) on circulating CC16 and IL-6 levels when used as the initial ventilation modes in preterm neonates.

STUDY DESIGN

Single center, prospective, randomized clinical study in preterm neonates (gestational age 30 weeks) requiring mechanical ventilation within the first 2 h of life. Serum CC16 and IL-6 were measured on establishment of the assigned ventilation mode after admission, at days 3 and 14 of life as well as at 36 weeks postmenstrual age. Demographic-perinatal data and clinical parameters were also recorded.

RESULT

Of the 30 neonates studied, 24 (gestational age 27.1±1.7 weeks, birth weight 942±214 g) were finally analyzed, equally assigned into the SIMV and HFOV groups. Both groups had comparable demographic-perinatal characteristics and clinical parameters. Serum CC16 and IL-6 altered significantly over time (repeated-measures analysis of variance, both P<0.001). However, changes were not affected by the ventilation mode. Post hoc analysis showed a significant decrease in CC16 and IL-6 from birth up to 36 weeks postmenstrual age in both groups.

CONCLUSION

In preterm neonates, SIMV and HFOV are associated with comparable circulating CC16 and IL-6 levels. These findings suggest a similar alveolar leakage and systemic inflammation with any of the ventilation modes evaluated when their usage is optimized.

A pathway-based approach to find novel markers of local glucocorticoid treatment in intermittent allergic rhinitis

BACKGROUND

Glucocorticoids (GCs) may affect the expression of hundreds of genes in different cells and tissues from patients with intermittent allergic rhinitis (IAR). It is a formidable challenge to understand these complex changes by studying individual genes. In this study, we aimed to identify (i) pathways affected by local GC treatment and (ii) examine if those pathways could be used to find novel markers of local GC treatment in nasal fluids from patients with IAR.

METHODS

Gene expression microarray- and iTRAQ-based proteomic analyses of nasal fluids, nasal fluid cells and nasal mucosa from patients with IAR were performed to find pathways enriched for differentially expressed genes and proteins. Proteins representing those pathways were analyzed with ELISA in an independent material of nasal fluids from 23 patients with IAR before and after treatment with a local GC.

RESULTS

Transcriptomal and proteomic high-throughput analyses of nasal fluids, nasal fluid cells and nasal mucosal showed that local GC treatment affected a wide variety of pathways in IAR such as the glucocorticoid receptor pathway and the acute phase response pathway. Extracellular proteins encoded by genes in those pathways were analyzed in an independent material of nasal fluids from patients. Proteins that changed significantly in expression included known biomarkers such as eosinophil cationic protein but also proteins that had not been previously described in IAR, namely CCL2, M-CSF, CXCL6 and apoH.

CONCLUSION

Pathway-based analyses of genomic and proteomic high-throughput data can be used as a complementary approach to identify novel potential markers of GC treatment in IAR.

The role of GSTP1 polymorphisms and tobacco smoke exposure in children with acute asthma

BACKGROUND

The glutathione S-transferase enzymes (GSTs) play an important role in the detoxification of environmental tobacco smoke (ETS), which contributes to airway inflammation, a key component of asthma. Genetic variation in GST genes may influence individuals' ability to detoxify environmental pollutants.

OBJECTIVE

To examine the role of polymorphisms in GSTP1 (Ile105Val and Ala114Val), alone and in combination with ETS exposure, on atopy and asthma severity.

METHODS

GSTP1 Ile105Val and Ala114Val were genotyped and ETS exposure was assessed by parental questionnaire, which was validated by urinary cotinine measurements. Associations between ETS exposure, GSTP1 polymorphisms, and their interaction on atopy and asthma severity were investigated.

RESULTS

For the functional GSTP1 105 SNP, those with the Ile/Ile genotype had odds for atopy of 2.77 (p = .054) when assessed by genotype alone, which increased to 9.02 (p = .050) when ETS was included, relative to individuals with other genotypes. Likewise, compared to children with other GSTP1 114 genotypes, those with Ala/Ala genotype had a 5.47-fold (p = .002) increased risk of atopy (p = .020) when assessed by genotype alone, increasing to 9.17-fold when ETS was included. The 105 Ile/Ile individuals all had the AA (105 Ile/Ile and 114 Ala/Ala) haplotype group; therefore, the odds for atopy were the same. Individuals without any *C haplotype (105 Val and 114 Val allele) who were exposed to ETS had a 9.17-fold increased risk of atopy when compared with individuals with at least one *C haplotype and not exposed to ETS (p = .020).

CONCLUSION

There were significant interactions between GSTP1 SNPs, atopy, and ETS exposure in this cohort.

Association of STR polymorphisms in CMA1 and IL-4 with asthma and atopy: the SAPALDIA cohort

Asthma is a chronic pulmonary disorder that is characterized by airway inflammation and bronchial hyperreactivity. Several genetic loci have been associated with asthma, and some of these associations have been replicated in independent studies. However, larger population-based replication studies for the association of short tandem repeat (STR) polymorphisms with asthma are limited. In this study, we investigated the association of STR polymorphisms in genes encoding mast cell chymase (CMA1), uteroglobin (UGB), tumor necrosis factor-α (TNF-α) and interleukin-4 (IL-4) with asthma and atopic phenotypes in the large population-based Swiss Cohort Study SAPALDIA. Our results show that the STR polymorphism in the CMA1 gene is associated with asthma and that this association is even stronger with atopic asthma. Similarly, we observed a weak association of the IL-4 2-allele with asthma that tended to be stronger for atopic asthma than for nonatopic asthma. This minor IL-4 2-allele was also associated with higher IgE levels, with a higher risk for a positive skin prick test and with a trend for a higher risk for bronchial hyperresponsiveness. These results support previous findings suggesting a role for CMA1 and IL-4 in atopic asthma and for IL-4 in atopy in general.

Association between human rhinovirus C and severity of acute asthma in children

A new and potentially more pathogenic group of human rhinovirus (HRV), group C (HRVC), has recently been discovered. We hypothesised that HRVC would be present in children with acute asthma and cause more severe attacks than other viruses or HRV groups. Children with acute asthma (n = 128; age 2-16 yrs) were recruited on presentation to an emergency department. Asthma exacerbation severity was assessed, and respiratory viruses and HRV strains were identified in a nasal aspirate. The majority of the children studied had moderate-to-severe asthma (85.2%) and 98.9% were admitted to hospital. HRV was detected in 87.5% and other respiratory viruses in 14.8% of children, most of whom also had HRV. HRVC was present in the majority of children with acute asthma (59.4%) and associated with more severe asthma. Children with HRVC (n = 76) had higher asthma severity scores than children whose HRV infection was HRVA or HRVB only (n = 34; p = 0.018), and all other children (n = 50; p = 0.016). Of the 19 children with a non-HRV virus, 13 had HRV co-infections, seven of these being HRVC. HRVC accounts for the majority of asthma attacks in children presenting to hospital and causes more severe attacks than previously known HRV groups and other viruses.

Association between CD14 gene polymorphisms and disease phenotype in sarcoidosis

Although the etiology of sarcoidosis is unknown, genetic susceptibility has been demonstrated. Granuloma formation is a key feature in the pathophysiology of sarcoidosis and Crohn's Disease, raising the possibility that these diseases share common pathogenetic pathways. An association between sarcoidosis and the protein "CD14", a molecule that is part of the lipopolysaccharide (LPS) cell surface receptor complex, has been suggested. In the current study we evaluated the CD14 gene promoter 159 C-->T polymorphic site and soluble CD14 levels in a cohort of 74 sarcoidosis patients compared to 85 healthy controls. We further sought to identify correlations between clinical phenotype, specific genotypes and soluble CD14 levels. We found the TT genotype to be more prevalent in the sarcoidosis patient group than in controls (p=0.03). Serum levels of soluble CD14 were higher in the sarcoidosis patients (p=0.001). Within the patient cohort, CC homozygous patients presented at an older age with milder disease as assessed with the SAC score, longer time to diagnosis, and less impairment of pulmonary function tests. Our study suggests a role of CD14 in the pathogenesis of sarcoidosis, and a clinical phenotype-genotype association. Further mechanistic and epidemiologic studies are needed in order to establish the specific role of CD14 in the etiology, pathogenesis and clinical phenotype of sarcoidosis.

CD14 polymorphisms and serum CD14 levels through childhood: a role for gene methylation?

BACKGROUND

CD14 is a pattern-recognition receptor for environmental LPS, and engagement of the CD14-LPS complex activates innate host defense mechanisms. Single nucleotide polymorphisms (SNPs) in the CD14 gene have been associated with soluble CD14 (sCD14) levels, but inconsistencies between studies suggest the presence of regulatory mechanisms hitherto not well understood.

OBJECTIVE

We sought to investigate possible associations between CD14 SNPs and sCD14 levels at different time points in childhood (at birth [cord blood] and 2 and 10 years) and to explore whether these associations were related to CD14 gene methylation.

METHODS

Four SNPs, rs2569191 (-1145GA), rs5744455 (-550CT or -651CT), rs2569190 (-159CT or -260CT), and rs4914 in CD14 were genotyped in 762 children from the Environmental and Childhood Asthma study. Genotype frequencies were analyzed for association with sCD14 levels in 660 babies, 346 children at age 2 years, and 360 children at age 10 years. In a subgroup of 157 children with DNA available at both 2 and 10 years of age, CD14 methylation patterns were determined and analyzed against detected CD14 gene-sCD14 associations.

RESULTS

rs2569191, rs5744455, and rs2569190 were associated with sCD14 levels at birth and 2 years, but only rs5744455 was associated with sCD14 levels at 10 years. CD14 methylation increased significantly from age 2 to 10 years, and the level of methylation was inversely correlated with sCD14 levels at 10 years.

CONCLUSION

The reduced effect of CD14 polymorphisms on sCD14 levels from early to late childhood paralleled a small but significant increase in CD14 methylation during the same period.

Airway regeneration: the role of the Clara cell secretory protein and the cells that express it

Clara cell secretory protein (CCSP) is one of the most abundant proteins in the airway surface fluid, and has many putative functions. Recent advances in the field of stem cells and lung regeneration have identified potentially new roles of CCSP and CCSP-expressing cell populations in airway maintenance, repair and regeneration. This review focuses on the airway regenerative potential of CCSP and the cells that express this protein. The use of this protein or CCSP-expressing cells as an indication of biologic processes that contribute to lung injury or repair is highlighted.

Opposite gene by environment interactions in Karelia for CD14 and CC16 single nucleotide polymorphisms and allergy

BACKGROUND

Finnish Karelians have a higher prevalence of allergic disease than Russian Karelians. As both populations are generally from the same ethnic group, the Karelian population offers a unique opportunity to analyse genetic and allergic disease interactions between 'Western' and 'Eastern' environments.

OBJECTIVES

We investigated associations between allergic diseases and CD14 and CC16 polymorphisms in Finnish vs Russian Karelian women.

METHODS

Adult female Karelians (330 Finnish and 274 Russian) were recruited, examined for a range of symptoms and conditions including rhinitis, itchy rash, asthma and atopy and genotyped for CD14 C-159T and CC16 A38G.

RESULTS

For both CD14 C-159T and CC16 A38G, the risk allele for atopic phenotypes in Finnish Karelia was the protective allele in Russian Karelia. For CD14 C-159T, an interactive effect on ever itchy rash (P(interaction) = 0.004), itchy rash <12 mo (P(interaction) = 0.001) and dry cough at night in the past 12 months (<12 months) (P(interaction) = 0.011) was found; the risk allele was C in Russians and T in Finns. For CC16 A38G, an interaction was significant for ever rhinitis (P(interaction) = 0.006), rhinitis <12 mo (P(interaction) = 0.004), and marginally significant for ever hayfever (P(interaction) = 0.07), allergic eye symptoms <12 mo (P(interaction) = 0.09); their risk allele was G in Russians and A in Finns.

CONCLUSION

An Eastern vs Western environment appears to exert an effect via opposite alleles on risk of allergic diseases in adult women.

Leukotriene pathway polymorphisms are associated with altered cysteinyl leukotriene production in children with acute asthma

Cysteinyl leukotrienes (cysLTs) are pro-inflammatory mediators with increasing evidence for a role in childhood acute asthma. This study examined the influence of polymorphisms in cysLT pathway genes on urinary leukotriene E(4) (uLTE(4)) levels and clinical status in acute asthmatic children. Children aged 2-16 years were recruited during an asthma attack (n=205). Where possible, asthma severity scores were assigned, ALOX5AP G-336A, ALOX5 G-1708A, LTC4S A-444C and G-1072A, GPX4 C718T, and CYSTLTR1 T927C genotypes were determined and uLTE(4) was measured in acute and convalescent samples. uLTE(4) levels were higher acutely compared with convalescence (acute GM: 115.7pg/mg creatinine; 95% CI 88.6-151.1, convalescence GM: 66.4pg/mg creatinine; 95% CI 51.5-85.6; n=50 paired samples, p=0.003) and paired sample analysis showed genotype-specific effects with significantly increased uLTE(4) for LTC(4)S-444AA (acute GM: 127.9pg/mg creatinine; 95% CI 91.8-178.3, convalescence GM: 68.2pg/mg creatinine; 95% CI 50.5-92.0; n=32, p=0.002), LTC(4)S-1072 GG (acute GM: 126.7pg/mg creatinine; 95% CI 95.4-168.3, convalescence GM: 78.9pg/mg creatinine; 95% CI 59.7-104.1; n=39, p=0.019) and CYSLTR1 927 TT/T_ (acute GM: 96.8pg/mg creatinine; 95% CI 73.8-126.9, convalescence GM: 62.4pg/mg creatinine; 95% CI 46.8-83.3; n=28, p=0.036) but not AC/CC, GA/AA, or TC/CC/C_, respectively. When we compared the allele frequencies of the CYSLTR1 SNP between asthmatics and non-asthmatics, the 927C allele was found to be a risk allele for asthma (OR=2.13, 95% CI: 1.06-4.26, p=0.033). Genotypes were not associated with acute or convalescent uLTE(4) levels alone and neither the SNPs nor uLTE(4) correlated with acute asthma severity. Leukotriene pathway gene polymorphisms may influence the magnitude of cysLT production during an attack, yet their influence alone may not be substantial enough to alter the severity of exacerbations.

Serum sCD14, polymorphism of CD14(-260) and periodontal infection

BACKGROUND AND AIMS

CD14 is a co-receptor involved in the recognition of Gram-negative and positive bacteria. Infections are known to influence serum sCD14 levels, and CD14 gene promoter polymorphism (CD14 C-260T) has been reported to be associated with many infectious diseases. Our aim was to investigate whether serum sCD14 concentration is associated with periodontal infection and the CD14(-260) genotype.

SUBJECTS AND METHODS

The periodontal status of 56 subjects with chronic periodontitis and 28 controls was clinically examined. Serum sCD14 concentration was analyzed using ELISA and CD14(-260) genotype using polymerase chain reaction (PCR).

RESULTS

The mean concentration of sCD14 in serum was significantly higher in subjects with periodontitis than in control subjects (4.9 microg ml(-1)vs 3.8 microg ml(-1), P < 0.001). Serum sCD14 concentration associated significantly with the extent of advanced periodontal disease. In a regression analysis including both subject groups, the CD14(-260) genotype was a significant determinant for serum sCD14 concentration. After stratification by periodontal health status (periodontitis vs controls), the influence of the CD14(-260) genotype on serum sCD14 concentration was seen only in the control group.

CONCLUSIONS

Periodontal infection is associated with the serum concentration of sCD14. Moderate to severe periodontal infection overshadows the influence of the genotype on serum sCD14 concentration.

Investigations into the role of ST2 in acute asthma in children

The ST2 gene is a member of the interleukin-1 receptor family and is located on chromosome 2q12, an area of the genome that has been associated with asthma. The soluble product of the ST2 gene, serum ST2 (sST2), has previously been shown to be elevated in adult asthmatic patients. This study investigated the potential role of ST2 in children with acute asthma. Children aged 2-16 years (n = 186) were recruited on presentation with acute asthma in the emergency department. Blood was obtained on presentation and during convalescence. Variables assessed included sST2 levels, a comprehensive assembly of clinical parameters and two polymorphisms in the ST2 gene, -26999G/A, located in the distal promoter region, and ala78glu polymorphism, on exon 3. The A allele of the -26999G/A polymorphism occurred more frequently in asthmatics compared with an unselected control group (P = 0.031). Serum ST2 levels were substantially higher during acute asthma compared with levels after the attack: 0.29 ng/ml (95% confidence interval: 0.23-0.36) and 0.14 ng/ml (0.12-0.17), respectively (P = 0.001) and were inversely related to eosinophil counts during an acute asthma attack (P = 0.002). The -26999AA genotype, as well as the AC haplotype, was associated with asthma severity scores (P = 0.05 and 0.02) compared with the -26999GA and GG genotypes. Serum ST2 levels were not associated with any of the studied genotypes or haplotypes. The observed associations of ST2 genotypes and haplotypes with acute asthma and asthma severity scores as well as the phenotypic differences associated with ST2 polymorphisms suggest that ST2 may play a role in the pathophysiology of asthma.

Anti-bacterial IgE in the antibody responses of house dust mite allergic children convalescent from asthma exacerbation

Background Atopic sensitization to the house dust mite (HDM) is associated with altered antibody responses to the nasopharyngeal colonizing bacterium Haemophilus influenzae and children admitted to the emergency department for asthma exacerbation have reduced IgG responses to HDM allergens.

Objective To investigate anti‐bacterial and anti‐allergen antibody responses during convalescence from asthma exacerbation and differences found in exacerbations associated with and without viral infection.

Results IgE antibodies to the P6 bacterial antigen increased in 60% of sera during convalescence and for many children achieved titres as high as IgE titres to allergens. In contrast IgE anti‐HDM titres declined during convalescence. The anti‐bacterial IgE titres were the same in subjects with and without virus infection while the anti‐HDM IgE declined more rapidly in virus‐infected subjects. IgG titres to the major HDM allergens showed no consistent increase and the overall IgG anti‐HDM titres even declined in subjects without a virus infection. Anti‐bacterial IgG antibodies in contrast to IgE did not change. Patients with frequent episodic or persistent asthma had similar IgE anti‐bacterial titres to patients with infrequent asthma during the acute phase, although they had reduced IgG titres to both the bacteria and the HDM.

Conclusions During the period following an acute exacerbation of asthma there was a marked and specific increase in anti‐bacterial IgE compared with a reduced IgE response to HDM. This provides further support for the concept of T‐helper type 2 responses to bacterial antigens playing a role in asthma pathogenesis.

An interdisciplinary analysis of sex and gender in relation to the pathogenesis of bronchial asthma

BACKGROUND

An increasing number of studies confirm that pathogenesis and prevalence of bronchial asthma are age and sex dependent. Detailed physiological mechanisms of the changing sex ratios with age are not fully known, however, the gender (socio-cultural) factors are also imperative. Although multiple factors definitely influence the pathogenesis of asthma, only individual or few combinations of these have been investigated.

METHODS

The terms 'sex', 'gender' and plausible combinations of both were systematically researched in selected databases (Medline, Scopus) or other sources, including publications from January 2000 to June 2007. Generated articles were categorized, either as endogenous or exogenous factors influencing the pathogenesis of asthma, and divided into the following subgroups: genetic, immunological, hormonal, gynaecological, nutritional, and environmental parameters.

RESULTS

An increasing number of studies investigate the influence of sex and gender in the aetiology, therapy and prevention of asthma. While their results are still debatable, others regarding its initiation, perpetuation and cessation have been clarified. Recent insights into interactions at biomolecular and immunological levels greatly contribute to clarifying sex-specific influences. Despite occasional oversimplifications, a trend for explanations considering the complex interplay of different factors can be observed. This work is in line with this trend and offers explanation models from our point of view.

CONCLUSIONS

Some disagreements regarding the patho-physiology, diagnosis, treatment and prevention of asthma still prevail. Nevertheless, in order to better appreciate its complexity, openness to and persistent consideration for interdisciplinary as well as sex- and gender-related factors is required of the medical-research community in future investigations.

Does the relationship between IgE and the CD14 gene depend on ethnicity?

This review considers the data from studies analysing associations between the CD14C-159T single nucleotide polymorphism (SNP) and asthmatic phenotypes and discusses the variability of the conclusions. By searching PubMed and EMBASE for articles on CD14C-159T -related population or family-based association studies, 47 were identified up till September 2007. Collectively, the studies reviewed herein consistently showed population differences in frequencies of the alleles of the SNP, with African descent having the highest C allele frequencies, followed by Caucasians and Asians. The T allele of the SNP was associated with increased sCD14 in some studies but not in others. Inconsistently, the C allele, or even occasionally the T allele, was associated with atopic phenotypes in a population subgroup. There are several explanations for these inconsistencies, including lack of power, linkage disequilibrium, gene-gene interactions, population admixture and gene-environment interactions. If the SNP was associated with functional changes to the coded protein and thus modulating susceptibility to allergic disease, its effect may be modest and dependent on other co-existent, ethnicity-specific, genetic or environmental risk factors.

Allergen-enhanced thrombomodulin (blood dendritic cell antigen 3, CD141) expression on dendritic cells is associated with a TH2-skewed immune response

BACKGROUND

Dendritic cells (DCs) are important in allergic diseases such as asthma, although little is known regarding the mechanisms by which DCs induce T(H)2-polarized responses in atopic individuals. It has been suggested that intrinsic properties of allergens can directly stimulate T(H)2 polarizing functions of DCs, but little is known of the underlying mechanisms.

OBJECTIVE

To identify novel genes expressed by house dust mite (HDM) allergen-exposed DCs.

METHODS

We screened for allergen-induced gene expression by microarray, and validated differentially expressed genes at the mRNA and protein levels.

RESULTS

Thrombomodulin (CD141, blood dendritic cell antigen 3) expression by microarray was higher on HDM-stimulated DCs from atopic (relative to nonatopic) individuals. These findings were confirmed at both the mRNA and protein levels in an independent group. Purified thrombomodulin(+) DCs induced a strongly T(H)2-polarized cytokine response by allergen-specific T cells compared with DCs lacking thrombomodulin. In vivo, thrombomodulin(+) circulating DCs were significantly more frequent in subjects with HDM allergy and asthma, compared with control subjects. Furthermore, thrombomodulin expression in blood leukocytes was higher in children with acute asthma than at convalescence 6 weeks later.

CONCLUSION

Thrombomodulin expression on DCs may be involved in the pathogenesis of atopy and asthma.

Beta2-adrenoceptor polymorphisms predict response to beta2-agonists in children with acute asthma

The aim of this study was to determine the influence of single nucleotide polymorphisms in the beta(2)-adrenoceptor gene, on the response to inhaled beta(2)-agonists in children with acute asthma. We hypothesised that children with polymorphisms that generate enhanced receptor downregulation in vitro, Gly16 and Gln27, would have a slower response to beta(2)-agonist therapy during acute asthma. One hundred and forty-eight children with acute asthma were recruited and genotyped for beta(2)Arg16Gly and beta(2)Gln27Glu. For Gln27Glu, individuals Gln27Gln took longest to stretch out to 1, 2 and 4 hourly beta(2)-agonists, followed by heterozygotes who were intermediate and Glu27Glu who responded most rapidly (1 hourly: 2.6 hr vs. 2.0 vs. 1.4, p = 0.02; 2 hourly: 10.6 hr vs. 10.7 vs. 6.8, p = 0.07; 4 hourly: 29.8 hr vs. 28.5 vs. 24.3, p = 0.30). The ability to prospectively identify children who respond less effectively to beta (2)-agonists during an acute asthma attack has the potential to allow the generation of genotype-specific treatment pathways.

Host defense genes in asthma and sepsis and the role of the environment

PURPOSE OF REVIEW

There is growing evidence that innate immunity genes contribute to asthma pathogenesis. At the core of the innate immune response are ubiquitous, soluble fragments of bacterial lipopolysaccharide or endotoxin, and chronic exposure to domestic endotoxin has been shown to influence asthma severity. Asthmatic and atopic individuals are more sensitive to endotoxin than nonallergic individuals, suggesting a role for genetics in the innate immunity response, and the potential for gene-environment interactions. Variants in genes associated with classic innate immunity-related disorders, such as sepsis, may be unique candidates for asthma susceptibility.

RECENT FINDINGS

Candidate genes for asthma and allergic diseases co-associated with sepsis including innate immunity receptors and related molecules (CD14, TLR4 and AOAH) and novel genes such as MYLK provide good examples of pleitropic effects of innate immunity genes, where variants conferring risk to specific traits (i.e. sepsis) under one set of genetic and environmental circumstances confer a reduced risk in a different (but possibly related) clinical outcome (i.e. allergic asthma), and support the 'common variant/multiple disease' hypothesis.

SUMMARY

Collectively, these observations suggest a greater role for the innate immunity response in allergic asthma than previously assumed, and implicate host defense genes in disease pathology.

Soluble CD14: role in atopic disease and recurrent infections, including otitis media

Soluble CD14 (sCD14) is a part of innate immunity that has been implicated in many diseases, including allergic diseases. However, many influencing factors and confounders, including gender-gene-environment interactions, may complicate interpretations of the observed associations to allergic diseases. In this paper, we review current literature describing the functions of sCD14 and its associations with common (recurrent) infections and with allergic diseases. Because sCD14 is involved with immunologic responses to infections, and exposure to microbial compounds is debated as a protective or a trigger factor for allergy development, these factors-which include genotypes, gender, age, microbial agents (from the environment and infection), and tobacco smoke-cannot be assessed independently. We conclude that confounding effects are important and must be considered to understand the role of sCD14 in allergic development.

Role of CD14 promoter polymorphisms in Helicobacter pylori infection--related gastric carcinoma

PURPOSE

Genetic variation in CD14 may affect CD14 expression and susceptibility to Helicobacter pylori infection-related cancers. This study examined functional single nucleotide polymorphisms (SNP) in the CD14 promoter and their associations with risk of developing gastric carcinoma in relation to H. pylori infection.

EXPERIMENTAL DESIGN

Thirty individual DNAs were sequenced to identify variants, and the function of the variants was examined by reporter gene assays. Genotypes and haplotypes were analyzed in 470 patients and 470 controls, and odds ratios (OR) and 95% confidence intervals (95% CI) were estimated by logistic regression. Serologic H. pylori antibody and soluble CD14 (sCD14) levels were measured by ELISA.

RESULTS

Two SNPs (-651C>T and -260C>T) were identified, of which the -260CT and -260TT genotypes were associated with elevated risk of gastric carcinoma (OR, 1.77; 95% CI, 1.09-2.85 and OR, 1.95; 95% CI, 1.20-3.16, respectively). Haplotype analysis suggested a synergistic effect of the two SNPs (OR for the T(-651)-T(-260) haplotype, 3.39 versus OR for the C(-651)-T(-260) haplotype, 1.45; P = 0.02), which is consistent with reporter gene assays. A multiplicative joint effect between H. pylori infection and -260C>T polymorphism was observed (OR for the presence of both -260TT genotype and H. pylori infection, 4.03; 95% CI, 1.80-9.04). Patients had significantly higher sCD14 than controls (1,866 +/- 2,535 ng/mL versus 1,343 +/- 2,119 ng/mL; P < 0.001), and this difference was associated with the CD14 -260 polymorphism and H. pylori infection.

CONCLUSIONS

Functional polymorphism in CD14 is associated with greater risk of H. pylori-related gastric carcinoma, which might be mediated by elevated sCD14.

African Americans with asthma: genetic insights

It has been well established that genetic factors strongly affect susceptibility to asthma and its associated traits. It is less clear to what extent genetic variation contributes to the ethnic disparities observed for asthma morbidity and mortality. Individuals of African descent with asthma have more severe asthma, higher IgE levels, a higher degree of steroid dependency, and more severe clinical symptoms than individuals of European descent with asthma but relatively few studies have focused on this particularly vulnerable ethnic group. Similar underrepresentation exists for other minorities, including Hispanics. In this review, a summary of linkage and association studies in populations of African descent is presented, and the role of linkage disequilibrium in the dissection of a complex trait such as asthma is discussed. Consideration for the impact of population stratification in recently admixed populations (i.e., European, African) is essential in genetic association studies focusing on African ancestry groups. With the most recent update on the International HapMap Project, efficient selection of haplotype tagging single nucleotide polymorphisms (htSNPs) for African Americans has accelerated and efficiency of htSNPs chosen from one population to represent other continental groups (e.g., African) has been demonstrated. Cutting-edge approaches, such as genomewide association studies, admixture mapping, and phylogenetic analyses, offer new opportunities for dissecting the genetic basis for asthma in populations of African descent.

Inverse relation between nasal fluid Clara Cell Protein 16 levels and symptoms and signs of rhinitis in allergen-challenged patients with intermittent allergic rhinitis

BACKGROUND

Decreased levels of the anti-inflammatory Clara Cell Protein 16 (CC16) are found in intermittent allergic rhinitis (IAR) and asthma. In asthma this decrease has been associated with hyperreactivity and the A38G single nucleotide polymorphism (SNP). The aim of this study was to examine if IAR is associated with signs and symptoms of rhinitis and the A38G SNP.

METHODS

Nasal fluid CC16 was analyzed in 20 patients with IAR before allergen challenge and 1 and 6 h after challenge, and from 28 healthy controls. The A38G SNP was analyzed in 80 patients with IAR and 106 controls. Nasal biopsies were obtained from three subjects in each group for immunohistochemical analysis of CC16.

RESULTS

In the allergen-challenged patients symptoms and rhinoscopic signs of rhinitis increased after 1 h and normalized after 6 h. In contrast, nasal fluid CC16 decreased 1 h after allergen challenge and returned to baseline after 6 h. Nasal fluid CC16 levels did not differ from controls before and 6 h after challenge. Immunohistochemical investigation showed intense CC16 staining in the nasal epithelium of both patients before season and healthy controls, but weak staining in symptomatic patients during season. No significant association between the A38G SNP and IAR was found.

CONCLUSION

There was an inverse relation between nasal fluid CC16 levels and symptoms and signs of rhinitis in allergen-challenged patients with IAR. However, there was no association between IAR and the A38G SNP.

Variations in genetic influences on the development of asthma throughout childhood, adolescence and early adult life

PURPOSE OF REVIEW

Asthma is likely to be due to many aetiological factors, the effect of each varying considerably with age. Now that there are well established candidate genes for asthma, using genetics to examine age-related susceptibility to asthma offers a new approach to understanding the basic underlying mechanisms.

RECENT FINDINGS

Since few long-term, longitudinal asthma studies exist, opportunities to examine age-related genetic susceptibility have been limited, but have produced some specific findings. The CCR5Delta32 polymorphism renders the chemokine receptor nonfunctional and is associated with reduced asthma susceptibility in children but not adults. In CD14 C-159T, the -159C allele has been associated with increased atopy in mid-childhood, but not in young adults. IL-12beta is a promoter polymorphism associated with reduced lung function in girls but not boys in mid-childhood only. Regarding the beta(2)adrenoceptor, results from three studies suggest that Arg16 can be associated with impaired airway function in infancy and Gly16 with asthma and wheeze in mid-childhood.

SUMMARY

Age-related genetic susceptibility studies are likely to make a major contribution to understanding basic mechanisms in asthma, but the limited number of suitable cohorts has meant that to date few studies have been reported.