Polymorphisms of endotoxin pathway and endotoxin exposure: in vitro IgE synthesis and replication in a birth cohort

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.

[Association of gene polymorphisms of MyD88 and TICAM1 and their interactions with community-acquired pneumonia in children]

OBJECTIVES

To investigate the association of single nucleotide polymorphisms (SNPs) of myeloid differentiation factor 88 (MyD88) and Toll-like receptor adaptor molecule 1 (TICAM1) and their interactions with community-acquired pneumonia (CAP) in children.

METHODS

Improved multiple ligase detection reaction assay was used for detecting the polymorphisms of nine tagging SNPs of the MyD88 and TICAM1 genes in 375 children with CAP who attended the Department of Pediatrics of the Second Affiliated Hospital of Yan'an University Medical School from August 2015 to September 2017 and 306 healthy children who underwent physical examination. A logistic regression analysis was used to evaluate the association between the distribution of genotypes and their interactions with CAP in children.

RESULTS

The polymorphism of the TICAM1 gene at rs11466711T/C locus was closely associated with the susceptibility to CAP in children (P<0.05). The AA genotype of rs35747610G/A locus significantly reduced risk of sepsis in children with CAP (P<0.05). The AA genotype of rs6510826G/A locus was significantly associated with the increase in C-reactive protein level in children with CAP (P<0.05). The GG genotype of the MyD88 gene at rs7744A/G locus significantly increased the risk of respiratory failure and circulatory failure (P<0.05). The multiplicative interactions between MyD88 gene rs7744A/G and TICAM1 gene rs11466711T/C, rs2292151G/A, rs35299700C/T, and rs35747610G/A loci were significantly associated with the susceptibility to CAP, the severity of CAP, and the risk of sepsis in children (P<0.05).

CONCLUSIONS

The gene polymorphisms of MyD88 and TICAM1 and their interactions are closely associated with CAP in children, with a synergistic effect on the development and progression of CAP in children.

The Genetic Variants of Interferon Regulatory Factor-3 in Children with Asthma

Interferon Regulatory Factor-3 (IRF-3) is one of the key players in the inflammatory response mediated by the innate immune system. Although many studies have implicated a role for IRF-3 in the pathogenesis of inflammatory airway diseases, information about the possible association of IRF-3 genetic variants with asthma is scarce. We aimed to investigate the potential effects of IRF-3 polymorphisms in childhood asthma and asthma-related phenotypes. IRF-3 polymorphisms were first determined by sequencing 25 asthmatic and 25 healthy children. For further analysis, 609 asthmatic children and 191 healthy controls were screened for the genetic variants, such as rs2304204, rs2304205, rs320440, rs34739574, and rs7251. In addition, the relationship between these polymorphisms and asthma-related phenotypic features, including forced expiratory volume in one second values, eosinophil counts, and IgE levels was determined. rs7251 was associated with asthma in the codominant (P = 0.049) and G dominant (P = 0.025) model, however this significance was lost after False Discovery Rate analysis. Other investigated single nucleotide polymorphisms (SNPs) showed no significant association with asthma or asthma-related phenotypes. In conclusion, the seven SNPs of IRF-3 gene are not associated with asthma or asthma-related phenotypes in Turkish asthmatic children.

Correlation between TICAM1 gene polymorphisms and community-acquired pneumonia in children

This study aims to explore the relationship between single nucleotide polymorphisms (SNPs) of the TICAM1 gene and community-acquired pneumonia (CAP) in Chinese children. The polymorphisms of eight tag SNP (TagSNP) locus of TICAM1 were detected using the improved multiplex ligation detection reaction (iMLDR) assay in 375 children with CAP (average age, 37.8 ± 21.6 months) and 306 healthy children (average age, 38.5 ± 23.8 months). The correlation between polymorphisms of these TagSNPs and the risk, severity, sepsis, and CRP level of childhood CAP were evaluated using logistic regression analysis. The CC genotype of rs11466711T/C locus of TICAM1 is correlated with childhood CAP susceptibility, which significantly reduced the risk of childhood CAP (P < .05), The AA genotype of the rs6510826G/A locus and haplotype CCCA were associated with CRP level in childhood CAP, which significantly increased the risk of CRP increase (P < .05 and P < .01, respectively), The AA genotype of rs35747610G/A site is associated with sepsis in childhood CAP, significantly reduced risk of sepsis (P < .05). While the haplotype CCCG of this locus led to a significant reduction in the risks of childhood CAP, severe pneumonia and pneumonia sepsis (all P < .05). TICAM1 has multiple functional variants closely related to the development and progression of childhood CAP, and these variations may have a synergistic effect on the development of childhood CAP.

Variations in CD14 Gene Are Associated With Autoimmune Thyroid Diseases in the Chinese Population

Autoimmune thyroid diseases (AITDs) are chronic organ-specific autoimmune diseases and mainly include Graves' disease (GD) and Hashimoto's thyroiditis (HT). CD14 is an important component of the immune system as a receptor for gram-negative lipopolysaccharide (LPS). The genetic polymorphisms of CD14 have been confirmed to be associated with a variety of autoimmune diseases. However, its relationship with AITDs is still unclear. The study was aimed to determine whether four single nucleotide polymorphisms (rs2915863, rs2569190, rs2569192, and rs2563298) of CD14 are associated with AITDs and its subgroups of GD and HT. The results showed significant association of rs2915863 and rs2569190 with GD. The frequencies of rs2915863 genotypes and T allele in patients with GD differed significantly from their controls (P = 0.007 and P = 0.021, respectively). For rs2569190, frequencies of genotypes and G allele in GD patients also showed positive P-values (P = 0.038 and P = 0.027, respectively). The correlations between these two loci and GD are more pronounced in female GD patients and patients with a family history. In genetic model analysis, the allele model, recessive model, and homozygous model of rs2569190 and rs2915863 embodied strong correlations with GD after the adjusting of age and gender (P = 0.014, P = 0.015, P = 0.009, and P = 0.014, P = 0.001, P = 0.006, respectively). However, these four sites are not related to HT. We firstly discovered the relationship between CD14 gene polymorphism and GD, and the results indicate that CD14 is an important risk locus for AITD and its SNPs may contribute to host's genetic predisposition to GD.

Features of asthma which provide meaningful insights for understanding the disease heterogeneity

BACKGROUND

Data-driven methods such as hierarchical clustering (HC) and principal component analysis (PCA) have been used to identify asthma subtypes, with inconsistent results.

OBJECTIVE

To develop a framework for the discovery of stable and clinically meaningful asthma subtypes.

METHODS

We performed HC in a rich data set from 613 asthmatic children, using 45 clinical variables (Model 1), and after PCA dimensionality reduction (Model 2). Clinical experts then identified a set of asthma features/domains which informed clusters in the two analyses. In Model 3, we reclustered the data using these features to ascertain whether this improved the discovery process.

RESULTS

Cluster stability was poor in Models 1 and 2. Clinical experts highlighted four asthma features/domains which differentiated the clusters in two models: age of onset, allergic sensitization, severity, and recent exacerbations. In Model 3 (HC using these four features), cluster stability improved substantially. The cluster assignment changed, providing more clinically interpretable results. In a 5-cluster model, we labelled the clusters as: "Difficult asthma" (n = 132); "Early-onset mild atopic" (n = 210); "Early-onset mild non-atopic: (n = 153); "Late-onset" (n = 105); and "Exacerbation-prone asthma" (n = 13). Multinomial regression demonstrated that lung function was significantly diminished among children with "Difficult asthma"; blood eosinophilia was a significant feature of "Difficult," "Early-onset mild atopic," and "Late-onset asthma." Children with moderate-to-severe asthma were present in each cluster.

CONCLUSIONS AND CLINICAL RELEVANCE

An integrative approach of blending the data with clinical expert domain knowledge identified four features, which may be informative for ascertaining asthma endotypes. These findings suggest that variables which are key determinants of asthma presence, severity, or control may not be the most informative for determining asthma subtypes. Our results indicate that exacerbation-prone asthma may be a separate asthma endotype and that severe asthma is not a single entity, but an extreme end of the spectrum of several different asthma endotypes.

Correlation between cell aggregation and antibody production in IgE-producing plasma cells

Allergic conditions result in the increase of immunoglobulin (Ig)E-producing plasma cells (IgE-PCs); however, it is unclear how IgE production is qualitatively controlled. In this study, we found that IgE-PCs in spleen of immunized mice formed homotypic cell aggregates. By employing IgE-producing hybridomas (IgE-hybridomas) as a model of IgE-PCs, we showed that these cells formed aggregates in the presence of specific antigens (Ags). The formation of the Ag-induced cell aggregation involved secreted IgE and Fcγ receptor (FcγR)II/FcγRIII, but not FcεRs. Ag-induced cell aggregation plus lipopolysaccharide signaling resulted in an enhancement of IgE production in aggregated IgE-hybridomas. Furthermore, the administration of anti-FcγRII/FcγRIII antagonistic monoclonal antibody to immunized mice tended to reduce the splenic IgE-PC aggregation as well as the serum IgE levels. Taken together, our results suggested that Ag-IgE complexes induced IgE-PCs aggregation via FcγRII/FcγRIII, leading to the enhancement of IgE production. These findings suggest the presence of a novel mechanism for regulation of IgE production.

Asthma phenotypes in childhood

PURPOSE OF REVIEW

This review describes the literature over the past 18 months that evaluated childhood asthma phenotypes, highlighting the key aspects of these studies, and comparing these studies to previous ones in this area.

RECENT FINDINGS

Recent studies on asthma phenotypes have identified new phenotypes on the basis of statistical analyses (using cluster analysis and latent class analysis methodology) and have evaluated the outcomes and associated risk factors of previously established early childhood asthma phenotypes that are based on asthma onset and patterns of wheezing illness. There have also been investigations focusing on immunologic, physiologic, and genetic correlates of various phenotypes, as well as identification of subphenotypes of severe childhood asthma.

SUMMARY

Childhood asthma remains a heterogeneous condition, and investigations into these various presentations, risk factors, and outcomes are important since they can offer therapeutic and prognostic relevance. Further investigation into the immunopathology and genetic basis underlying childhood phenotypes is important so therapy can be tailored accordingly.

Domestic dog exposure at birth reduces the incidence of atopic dermatitis

BACKGROUND

While the etiopathogenesis of atopic dermatitis is complex and poorly understood, neonatal exposures are important for disease occurrence. However, the effect of dog exposure on the risk of atopic dermatitis is unresolved.

OBJECTIVE

We investigated whether domestic dog exposure affected the risk of atopic dermatitis in children during the first 3 years of life.

METHODS

Copenhagen Prospective Studies on Asthma in Childhood (COPSAC) are ongoing prospective clinical birth cohort studies. Data from 411 children born to mothers with asthma (COPSAC₂₀₀₀ ) and 700 unselected children (COPSAC₂₀₁₀ ) were analyzed following the same protocols at the same research site. Atopic dermatitis was diagnosed prospectively according to the Hanifin-Rajka criteria. Parental history of asthma, eczema, or rhinitis was defined by self-reported physician diagnosis. In the COPSAC₂₀₀₀ , maternal specific serum IgE against eight inhalant allergens was sampled after the children's birth and at pregnancy week 24 in the COPSAC₂₀₁₀ cohort. Associations between dog exposure and atopic dermatitis were analyzed by Cox proportional hazard regression models and adjusted for lifestyle confounders.

RESULTS

In the COPSAC₂₀₀₀ and COPSAC₂₀₁₀ cohorts, the risk of atopic dermatitis was significantly lower in children with domestic dog exposure (_adjusted HR = 0.46 [0.25-0.87], P = 0.02; and _adjusted HR = 0.58 [0.36-0.93], P = 0.03, respectively). The risk of atopic dermatitis decreased in a dose-dependent manner with increasing number of dogs (_adjusted HR = 0.58 [0.38-0.89], P = 0.01) in the COPSAC₂₀₁₀ . The protective effect was restricted to children born to mothers with atopic disease in the unselected COPSAC₂₀₁₀ cohort (_adjusted HR = 0.39 [0.19-0.82], P = 0.01), as no effect was observed in children born to mothers without atopic disease (_adjusted HR = 0.92 [0.49-1.73], P = 0.79). Paternal atopic status did not affect the risk of atopic dermatitis. We found no significant interaction between the CD14 T/T genotype and domestic dog exposure in either cohort (COPSAC₂₀₀₀ , P = 0.36; and COPSAC₂₀₁₀ cohort, P = 0.42).

CONCLUSION

Neonatal domestic dog exposure was associated with a strongly reduced risk of atopic dermatitis in two independent birth cohorts and in a dose-dependent manner. While the mechanisms involved are unclear, our findings raise the question of whether in utero exposures may affect the risk of atopic dermatitis and emphasize the importance of the early environment for disease trajectory.

Latest developments in allergic rhinitis in Allergy for clinicians and researchers

Research efforts in allergic rhinitis have always been intense. Over the past 3 years, numerous breakthroughs in basic science and clinical research have been made, augmenting our understanding of this condition that afflicts a significant proportion of the global population. New epidemiological findings, novel insights into the molecular and cellular mechanisms of allergy, enhancement of current developmental theories, new concepts of the goals and endpoints of management, and latest therapeutic modalities that includes the harnessing of information technology and big data are some areas where important advances were made. We attempt to bring you a summary of the key research advances made in the field of allergic rhinitis from 2013 to 2015.

TRIF Deficiency does not Affect Severity of Ovalbumin-induced Airway Inflammation in Mice

Allergic asthma is a chronic pulmonary inflammatory disease characterized by reversible airway obstruction, hyperresponsiveness and eosinophils infiltration. Toll-like receptors (TLRs) signaling are closely associated with asthma and have emerged as a novel therapeutic target in allergic disease. The functions of TLR3 and TLR4 in allergic airway inflammation have been studied; however, the precise role of TIR-domain-containing adapter-inducing interferon-β (TRIF), the adaptor molecule for both TLR3 and TLR4, is not yet fully understood. To investigate this, we developed a mouse model of OVA-induced allergic airway inflammation and compared the severity of allergic airway inflammation in WT and TRIF^-/- mice. Histopathological assessment revealed that the severity of inflammation in airway inflammation in TRIF-deficient mice was comparable to that in WT mice. The total number of cells recovered from bronchoalveolar lavage fluid did not differ between WT and TRIF-deficient mice. Moreover, TRIF deficiency did not affect Th1 and Th2 cytokine production in lung tissue nor the level of serum OVA-specific IgE, IgG₁ and IgG_2c. These findings suggest that TRIF-mediated signaling may not be critical for the development of allergic airway inflammation.