Genetic variants in endotoxin signalling pathway, domestic endotoxin exposure and asthma exacerbations

Chalcone-derivative L6H21 attenuates the OVA-induced asthma by targeting MD2

Asthma represents a significant global challenge that affects individuals across all age groups and imposes substantial social and economic burden. Due to heterogeneity of the disease, not all patients obtain benefit with current treatments. The objective of this study was to explore the impact of MD2 on the progression of asthma using L6H21, a novel MD2 inhibitor, to identify potential targets and drug candidates for asthma treatment. To establish an asthma-related murine model and evaluate the effects of L6H21, ovalbumin (OVA) was used to sensitize and challenge mice. Pathological changes were examined with various staining techniques, such as H&E staining, glycogen staining, and Masson staining. Inflammatory cell infiltration and excessive cytokine secretion were evaluated by analyzing BALF cell count, RT-PCR, and ELISA. The TLR4/MD2 complex formation, as well as the activation of the MAPK and NF-кB pathways, was examined using western blot and co-IP. Treatment with L6H21 demonstrated alleviation of increased airway resistance, lung tissue injury, inflammatory cell infiltration and excessive cytokine secretion triggered by OVA. In addition, it also ameliorated mucus production and collagen deposition. In the L6H21 treatment group, inhibition of MAPK and NF-кB activation was observed, along with the disruption of TLR4/MD2 complex formation, in contrast to the model group. Thus, L6H21 effectively reduced the formation of the MD2 and TLR4 complex induced by OVA in a dose-dependent manner. This reduction resulted in the attenuation of MAPKs/NF-κB activation, enhanced suppression of inflammatory factor secretion, reduced excessive recruitment of inflammatory cells, and ultimately mitigated airway damage. MD2 emerges as a crucial target for asthma treatment, and L6H21, as an MD2 inhibitor, shows promise as a potential drug candidate for the treatment of asthma.

Association of genetic variants of oxidative stress responsive kinase 1 (OXSR1) with asthma exacerbations in non-smoking asthmatics

BACKGROUND

Asthma exacerbation threatens patient's life. Several genetic studies have been conducted to determine the risk factors for asthma exacerbation, but this information is still lacking. We aimed to determine whether genetic variants of Oxidative Stress Responsive Kinase 1 (OXSR1), a gene with functions of salt transport, immune response, and oxidative stress, are associated with exacerbation of asthma.

METHODS

Clinical data were obtained from 1454 asthmatics and single nucleotide polymorphisms (SNPs) of OXSR1 were genotyped. Genetic associations with annual exacerbation rate were analyzed depending on smoking status.

RESULTS

Eleven SNPs were selected using Asian data in the International HapMap database. The common allele of rs1384006 C > T of OXSR1 showed a significantly higher annual exacerbation rate than the rare allele in non-smoking asthmatics (CC vs. CT vs. TT: 0.43 ± 0.04 vs. 0.28 ± 0.03 vs. 0.31 ± 0.09, P = 0.004, Pcorr = 0.039). The frequent exacerbators had a significantly higher frequency of the common allele of rs1384006 C > T than did the infrequent exacerbators (74.4% vs. 55.2%, P = 0.004, Pcorr = 0.038).

CONCLUSION

The common allele of rs1384006 C > T of OXSR1 was associated with the asthma exacerbation rate and a higher risk of being a frequent exacerbator, indicating that non-smoking asthmatics who carry common alleles may be vulnerable to asthma exacerbations.

The Impact of Ambient Environmental Exposures to Microbial Products on Asthma Outcomes from Birth to Childhood

Purpose of Review

Asthma is a chronic respiratory condition with increasing domestic and worldwide prevalence that burdens individuals and the healthcare system with high costs associated with long-term treatments and acute emergency room (ER) visits. It can be triggered by ambient microbes, including bacteria, viruses, and fungi. In this review, we examine the outcomes of asthma patients in relation to environmental exposures to ambient microbe products, focusing on whether exposure leads to asthma development from birth to childhood and if particular microbes are associated with worsened asthma exacerbations.

Recent Findings

Bacterial endotoxin is more prominent in homes with pets and may cause cytokine cascades that lead to asthma exacerbation. However, some studies have demonstrated a protective effect with early exposure. Patients with positive Aspergillus skin testing are more prone to moderate-severe or severe-uncontrolled asthma. Fungal sensitization is also associated with earlier onset of asthma and demonstrates a dose-dependent relationship of symptom severity and duration. Among viruses, rhinovirus has the greatest association with decreased lung function, severe asthma, and asthma-related hospital admissions. Distribution of microbial products and associated asthma symptoms depends on the geographical climate. Genetic variations among individuals also mitigate the effects of microbial products on asthma development and symptom severity.

Summary

Microbial products of bacteria, fungi, and viruses are associated with the development of asthma, more severe asthma symptoms, and worse outcomes. However, some early exposure studies have also demonstrated a protective effect. Bacterial and fungal products are related to decreased lung function and earlier onset of asthma. Viral products are related to asthma-associated hospital admissions; and the climate and patient genetics can also temper or intensify the relationships between microbial products, asthma development, and asthma symptom severity. Further research should focus on the effects of early microbe exposure and its interaction with human immune systems and asthma-related outcomes.

House Dust Endotoxin Levels Are Associated with Adult Asthma in a U.S. Farming Population

RATIONALE

Endotoxin initiates a proinflammatory response from the innate immune system. Studies in children suggest that endotoxin exposure from house dust may be an important risk factor for asthma, but few studies have been conducted in adult populations.

OBJECTIVES

To investigate the association of house dust endotoxin levels with asthma and related phenotypes (wheeze, atopy, and pulmonary function) in a large U.S. farming population.

METHODS

Dust was collected from the bedrooms (n = 2,485) of participants enrolled in a case-control study of current asthma (927 cases) nested within the Agricultural Health Study. Dust endotoxin was measured by Limulus amebocyte lysate assay. Outcomes were measured by questionnaire, spirometry, and blood draw. We evaluated associations using linear and logistic regression.

MEASUREMENTS AND MAIN RESULTS

Endotoxin was significantly associated with current asthma (odds ratio [OR], 1.30; 95% confidence interval [CI], 1.14-1.47), and this relationship was modified by early-life farm exposure (born on a farm: OR, 1.18; 95% CI, 1.02-1.37; not born on a farm: OR, 1.67; 95% CI, 1.26-2.20; Interaction P = 0.05). Significant positive associations were seen with both atopic and nonatopic asthma. Endotoxin was not related to either atopy or wheeze. Higher endotoxin was related to lower FEV₁/FVC in asthma cases only (Interaction P = 0.01). For asthma, there was suggestive evidence of a gene-by-environment interaction for the CD14 variant rs2569190 (Interaction P = 0.16) but not for the TLR4 variants rs4986790 and rs4986791.

CONCLUSIONS

House dust endotoxin was associated with current atopic and nonatopic asthma in a U.S. farming population. The degree of the association with asthma depended on early-life farm exposures. Furthermore, endotoxin was associated with lower pulmonary function in patients with asthma.

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.

Genetic Signatures of Asthma Exacerbation

Asthma exacerbation (AE) usually denotes worsening of asthma symptoms that requires intense management to prevent further deterioration. AE has been reported to correlate with clinical and demographic factors, such as race, gender, and treatment compliance as well as environmental factors, such as viral infection, smoking, and air pollution. In addition, recent observations suggest that there are likely to be genetic factors specific to AE. Understanding genetic factors specific to AE is essential to develop therapy tailored for exacerbation-prone asthma. Here, we summarize the results of studies involving genetic risk factors for AE. To simplify and enhance understanding, we reviewed the studies according to the following categories: hypothesis-driven approaches, hypothesis-free approaches, gene-environment interactions, and pharmacogenetics.

Association of CD14 -159 (-260C/T) polymorphism and asthma risk: an updated genetic meta-analysis study

BACKGROUND

It has been reported that the cluster of differentiation 14 (CD14) gene -159C/T variant may be associated with asthma risk. However, some studies yielded conflicting results. Therefore, a comprehensive meta-analysis was designed to assess the precise association.

METHODS

A systematic search in PubMed, Embase (Ovid), China National Knowledge Internet (CNKI), and Wan fang databases was conducted up to August 15, 2015. Odds ratio (OR) and 95% confidence interval (CI) were used to pool the effect size. We used I to assess heterogeneity, and a funnel plot and Egger test to assess publication bias.

RESULTS

In total, 34 studies involving 15,641 subjects were included in this meta-analysis. There was a statistically significant association between CD14 -159C/T polymorphism and asthma risk observed in dominant model (TT+TC vs CC: OR = 0.86, 95% CI = 0.77-0.97, P = 0.012) and codominant model (TC vs CC: OR = 0.88, 95% CI = 0.78-0.99, P = 0.035) in adults. However, there may be no significant association between CD14 159C/T and atopic and nonatopic asthma risk.

CONCLUSION

In summary, the overall results suggested that the CD14 -159C/T variant may decrease the risk of asthma susceptibility in adults. However, no significant association between CD14 159C/T and atopic and nonatopic asthma susceptibility was identified. More studies with larger sample size are needed to validate the findings from this study.

Patterns of IgE responses to multiple allergen components and clinical symptoms at age 11 years

BACKGROUND

The relationship between sensitization to allergens and disease is complex.

OBJECTIVE

We sought to identify patterns of response to a broad range of allergen components and investigate associations with asthma, eczema, and hay fever.

METHODS

Serum specific IgE levels to 112 allergen components were measured by using a multiplex array (Immuno Solid-phase Allergen Chip) in a population-based birth cohort. Latent variable modeling was used to identify underlying patterns of component-specific IgE responses; these patterns were then related to asthma, eczema, and hay fever.

RESULTS

Two hundred twenty-one of 461 children had IgE to 1 or more components. Seventy-one of the 112 components were recognized by 3 or more children. By using latent variable modeling, 61 allergen components clustered into 3 component groups (CG1, CG2, and CG3); protein families within each CG were exclusive to that group. CG1 comprised 27 components from 8 plant protein families. CG2 comprised 7 components of mite allergens from 3 protein families. CG3 included 27 components of plant, animal, and fungal origin from 12 protein families. Each CG included components from different biological sources with structural homology and also nonhomologous proteins arising from the same biological source. Sensitization to CG3 was most strongly associated with asthma (odds ratio [OR], 8.20; 95% CI, 3.49-19.24; P < .001) and lower FEV1 (P < .001). Sensitization to CG1 was associated with hay fever (OR, 12.79; 95% CI, 6.84-23.90; P < .001). Sensitization to CG2 was associated with both asthma (OR, 3.60; 95% CI, 2.05-6.29) and hay fever (OR, 2.52; 95% CI, 1.38-4.61).

CONCLUSIONS

Latent variable modeling with a large number of allergen components identified 3 patterns of IgE responses, each including different protein families. In 11-year-old children the pattern of response to components of multiple allergens appeared to be associated with current asthma and hay fever but not eczema.