CD14 promoter polymorphisms in atopic families: implications for modulated allergen-specific immunoglobulin E and G1 responses

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.

International consensus (ICON) on: clinical consequences of mite hypersensitivity, a global problem

Since mite allergens are the most relevant inducers of allergic diseases worldwide, resulting in significant morbidity and increased burden on health services, the International Collaboration in Asthma, Allergy and Immunology (iCAALL), formed by the American Academy of Allergy, Asthma and Immunology (AAAAI), the American College of Allergy, Asthma and Immunology (ACAAI), the European Academy of Allergy and Clinical Immunology (EAACI), and the World Allergy Organization (WAO), has proposed to issue an International Consensus (ICON) on the clinical consequences of mite hypersensitivity. The objectives of this document are to highlight aspects of mite biology that are clinically relevant, to update the current knowledge on mite allergens, routes of sensitization, the genetics of IgE responses to mites, the epidemiologic aspects of mite hypersensitivity, the clinical pictures induced by mites, the diagnosis, specific immunotherapeutic approaches, and prevention.

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.

Racial differences in the association of CD14 polymorphisms with serum total IgE levels and allergen skin test reactivity

Background

The CD14 C-159T single nucleotide polymorphism (SNP) has been investigated widely as a candidate genetic locus in patients with allergic disease. There are conflicting results for the association of the CD14 C-159T SNP with total serum immunoglobulin E (IgE) levels and atopy. There are limited data regarding the association of the CD14 C-159T SNP in subjects of African ancestry. The aim of the study was to determine whether the C-159T SNP and other CD14 SNPs (C1188G, C1341T) were associated with total serum IgE levels and with allergy skin test results in nonatopic and atopic subjects; as well as in Caucasian and African American subjects.

Methods

A total of 291 participants, 18–40 years old, were screened to determine whether they were atopic and/or asthmatic. Analyses were performed to determine the association between CD14 C-159T, C1188G, or C1341T genotypes with serum IgE levels and with the number of positive skin tests among Caucasian or African American subjects.

Results

We found no significant association of serum total IgE level with CD14 C-159T, C1188G, or C1341T genotypes within nonatopic or atopic subjects. Subjects with CD14-159 T alleles had significantly more positive allergen skin tests than subjects without CD14-159 T alleles (P = 0.0388). There was a significant association between the CD14 1188 G allele, but not the CD14 1341 T allele, with the number of positive skin-test results in Caucasians, but not in African Americans.

Conclusion

These results support a possible association between CD14 polymorphisms and atopy. CD14-159 T or CD14 1188 G alleles were associated with atopic disease. For subjects with CD14 1188 G alleles, the association with atopic disease was stronger in Caucasians compared to African Americans.

Toll-like receptors and human disease: lessons from single nucleotide polymorphisms

Toll-like receptors (TLRs), a large group of proteins which recognize various pathogen-associated molecular patterns, are critical for the normal function of the innate immune system. Following their discovery many single nucleotide polymorphisms within TLRs and components of their signaling machinery have been discovered and subsequently implicated in a wide range of human diseases including atherosclerosis, sepsis, asthma, and immunodeficiency. This review discusses the effect of genetic variation on TLR function and how they may precipitate disease.

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.

Sensitization to cockroach allergen: immune regulation and genetic determinants

Asthma is a major public health concern. Cockroach allergen exposure and cockroach allergic sensitization could contribute to the higher prevalence of asthma. However, the underlying immune mechanism and the genetic etiology remain unclear. Recent advances have demonstrated that several receptors (PAR-2, TLRs, CLRs) and their pathways mediate antigen uptake from the environment and induce allergies by signaling T cells to activate an inappropriate immune response. Cockroach-derived protease can disturb airway epithelial integrity via PAR-2 and leads to an increased penetration of cockroach allergen, resulting in activation of innate immune cells (e.g., DCs) via binding to either TLRs or CLRs. The activated DCs can direct cells of the adaptive immune system to facilitate promotion of Th2 cell response and subsequently increase risk of sensitization. Mannose receptor (MR), as a CLR, has been shown to mediate Bla g2 (purified cockroach allergen) uptake by DCs and to determine allergen-induced T cell polarization. Additionally, genetic factors may play an important role in conferring the susceptibility to cockroach sensitization. Several genes have been associated with cockroach sensitization and related phenotypes (HLA-D, TSLP, IL-12A, MBL2). In this review, we have focused on studies on the cockroach allergen induced immunologic responses and genetic basis for cockroach sensitization.

CD14, a key candidate gene associated with a specific immune response to cockroach

BACKGROUND

Sensitization to cockroach allergen is one of the strongest predictors of asthma morbidity, especially among African Americans.

OBJECTIVE

Our aims were to determine the genomic basis of cockroach sensitization and the specific response to cockroach antigen.

METHODS

We investigated the Th1/Th2 cytokine profile of co-cultured plasmacytoid dendritic cells (pDCs) and CD4+ T cells and the 'transcript signature' of the immune response to cockroach antigen using high-throughput expression profiling of co-cultured cells.

RESULTS

We observed significantly elevated levels of IL-13, IL-10, and TNF-alpha, but undetectable levels of IL-12p70 and IFN-alpha, when cultures were exposed to crude cockroach antigen. A significant difference was observed for IL-13 between cockroach-allergic and non-allergic individuals (P=0.039). Microarray analyses demonstrated a greater response at 48 h compared with 4 h, with 50 genes being uniquely expressed in cockroach antigen-treated cells, including CD14, S100A8, CCL8, and IFI44L. The increased CD14 expression was further observed in purified pDCs, human monocytic THP-1 cells, and the supernatant of co-cultured pDCs and CD4+ T cells on exposure to cockroach extract. Furthermore, the most differential expression of CD14 between cockroach allergy and non-cockroach allergy was only observed among individuals with the CC 'high-risk' genotype of the CD14-260C/T. Ingenuity Pathways Analysis analyses suggested the IFN signalling as the most significant canonical pathway.

CONCLUSION

Our results suggest that these differentially expressed genes, particularly CD14, and genes in the IFN signalling pathway may be important candidates for further investigation of their role in the immune response to cockroach allergen.

Genetic factors in the treatment of bronchial asthma

Owing to the recent vast progress in analytical tools and procedures to elucidate the relationship between genes and diseases, many candidate genes leading to the development of bronchial asthma have been reported. However, the quantitative phenotypes of asthma, such as decrease in forced expiratory volume in the first second, serum hyper-IgE, bronchial hyperresponsiveness and blood hyper-eosinophilia, do not represent this disease completely. On the other hand, eosinophilic inflammation of the bronchial mucosa represents accurately the feature of bronchial asthma, although accurate quantification of its status is difficult. While the production of interleukin (IL)-5 in peripheral CD4(+) T cells probably correlates with eosinophilic inflammation of the airway, the effectiveness of anti-IL-5 antibody for the treatment of bronchial asthma is controversial. Since intervention with asthma-causing gene products may not be sufficient for the treatment of this disease, identification of therapy-responsive genes should become more important in the near future.

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.

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.

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.

Association between CD14 polymorphisms and serum soluble CD14 levels: effect of atopy and endotoxin inhalation

BACKGROUND

A prerequisite for activation of the innate immune response by endotoxin is its binding to CD14.

OBJECTIVE

The aim of this study was to evaluate the role of CD14 polymorphisms, atopy, and inhaled endotoxin in modulating serum CD14 levels.

METHODS

Healthy volunteers (n = 88) were genotyped for CD14 polymorphisms at the -1619, -1359, and -159 loci, relative to the transcription start site. Subjects inhaled 20 mug of endotoxin, and white blood cell, C-reactive protein, LPS-binding protein, and soluble CD14 (sCD14) levels were measured before and after exposure.

RESULTS

Homozygotes for the -1619G, -1359G, and -159T alleles had higher baseline levels of sCD14 than carriers of the CD14/-1619AA (P = .015), -1359GT/TT (P = .015), or -159CC (P = 0.017) genotypes. sCD14 levels increased within 24 hours of endotoxin inhalation (P < .0001 for all biomarkers); however, the association between CD14 polymorphisms and sCD14 levels was no longer present after exposure. The atopic status of an individual did not alter these associations. CD14 polymorphisms were not associated with levels of white blood cells, C-reactive protein, and LPS-binding protein before or after endotoxin challenge.

CONCLUSION

These data suggest that CD14 promoter polymorphisms and inhaled endotoxin modulate sCD14 levels.

Allergen-specific IgG1 provides parsimonious heritability estimates for atopy-associated immune responses to allergens

Although serum total immunoglobulin E (IgE) is generally elevated in atopic conditions, it is an unreliable trait for dissecting the genetic and environmental components contributing to atopic immune responses, because it can be significantly confounded by demographic factors (age, gender, and race) and clinical status (atopic vs nonatopic). Allergen-specific IgE is a discontinuous trait present only in those with sensitivity to allergens. However, all people will produce allergen-specific immunoglobulin G1 (IgG1), which is elevated among those atopically sensitized to specific allergens. We screened 91 Caucasian nuclear families (N = 367) with medical histories of atopic diseases and used variance components analysis to compare heritability estimates for total IgE and IgG1 produced against the common major allergen from house dust mite Dermatophagoides pteronyssinus (Der p 1). An estimate of total IgE heritability was about 48%, although this was significantly confounded by age, gender, and clinical atopic status. In contrast, Der p 1-IgG1 demonstrated a significant inherited component of about 62% that was not influenced by age, gender, or clinical status. For genetic studies of atopic humoral responses, allergen-specific IgG1 may be a more reliable quantitative trait than serum IgE. Moreover, atopy is an inherited deregulation of immune responses to noninfectious antigens, involving antibody isotypes other than IgE.