Innate microbial sensors and their relevance to allergy

Integrative Transcriptomics Reveals Activation of Innate Immune Responses and Inhibition of Inflammation During Oral Immunotherapy for Egg Allergy in Children

We previously reported the results of a randomized, open-label trial of egg oral immunotherapy (OIT) in 50 children where 44% were desensitized and 46% were partially desensitized after 8 months of treatment. Here we focus on cell-mediated molecular mechanisms driving desensitization during egg OIT. We sought to determine whether changes in genome-wide gene expression in blood cells during egg OIT correlate with humoral responses and the clinical outcome. The blood cell transcriptome of 50 children receiving egg OIT was profiled using peripheral blood mononuclear cell (PBMC) samples obtained at baseline and after 3 and 8 months of OIT. We identified 467 differentially expressed genes (DEGs) after 3 or 8 months of egg OIT. At 8 months, 86% of the DEGs were downregulated and played a role in the signaling of TREM1, IL-6, and IL-17. In correlation analyses, Gal d 1–4-specific IgG4 antibodies associated positively with DEGs playing a role in pathogen recognition and antigen presentation and negatively with DEGs playing a role in the signaling of IL-10, IL-6, and IL-17. Desensitized and partially desensitized patients had differences in their antibody responses, and although most of the transcriptomic changes were shared, both groups had also specific patterns, which suggest slower changes in partially desensitized and activation of NK cells in the desensitized group. OIT for egg allergy in children inhibits inflammation and activates innate immune responses regardless of the clinical outcome at 8 months. Changes in gene expression patterns first appear as posttranslational protein modifications, followed by more sustained epigenetic gene regulatory functions related to successful desensitization.

The infant gut bacterial microbiota and risk of pediatric asthma and allergic diseases

Among the many areas being revolutionized by the recent introduction of culture-independent microbial identification techniques is investigation of the relationship between close contact with large animals, antibiotics, breast feeding, mode of birth, and other exposures during infancy as related to a reduced risk of asthma and allergic disease. These exposures were originally clustered under the "Hygiene Hypothesis" which has evolved into the "Microbiota Hypothesis". This review begins by summarizing epidemiologic studies suggesting that the common feature of these allergy risk-related exposures is their influence on the founding and early development of a child's gut microbiota. Next, studies using culture-independent techniques are presented showing that children who have experienced the exposures of interest have altered gut microbiota. Finally, selected mouse and human studies are presented which begin to corroborate the protective exposures identified in epidemiologic studies by elucidating mechanisms through which microbes can alter immune development and function. These microbially driven immune alterations demonstrate that microbial exposures in many cases could alter the risk of subsequent allergic disease and asthma. Hopefully, a better understanding of how microbes influence allergic disease will lead to safe and effective methods for reducing the prevalence of all forms of allergic disease.

Controlled diesel exhaust and allergen coexposure modulates microRNA and gene expression in humans: Effects on inflammatory lung markers

BACKGROUND

Air pollution's association with asthma may be due to its augmentation of allergenic effects, but the role of microRNA (miRNA) and gene expression in this synergy is unknown.

OBJECTIVE

We sought to determine whether exposure to allergen, exposure to diesel exhaust (DE), or coexposures modulate miRNA, gene expression, or inflammatory pathways and whether these measurements are correlated.

METHODS

Fifteen participants with atopy completed this controlled study of 2 hours of filtered air or DE (300 μg PM_2.5/m³) exposure, followed by saline-controlled segmental bronchial allergen challenge. Gene and miRNA expression in bronchial brushings and lung inflammatory markers were measured 48 hours later, in study arms separated by approximately 4 weeks. Expression of miRNAs, messenger RNAs, and inflammatory markers and their interrelationships were determined using regression.

RESULTS

Robust linear models indicated that DE plus saline and DE plus allergen significantly modulated the highest number of miRNAs and messenger RNAs, respectively, relative to control (filtered air plus saline). In mixed models, allergen exposure modulated (q ≤ 0.2) miRNAs including miR-183-5p, miR-324-5p, and miR-132-3p and genes including NFKBIZ and CDKN1A, but DE did not significantly modify this allergenic effect. Repression of CDKN1A by allergen-induced miR-132-3p may contribute to shedding of bronchial epithelial cells.

CONCLUSIONS

Expression of specific miRNAs and genes associated with bronchial immune responses were significantly modulated by DE or allergen. However, DE did not augment the effect of allergen at 48 hours, suggesting that adjuvancy may be transient or require higher or prolonged exposure. In silico analysis suggested a possible mechanism contributing to epithelial wall damage following allergen exposure.

Food allergy: temporal trends and determinants

This review summarizes studies discussing temporal trends in the prevalence of food allergy as well as potential factors associated with the development of food allergy. In addition, we will address the potential hypotheses accounting for the apparent increase in food allergy prevalence. Studies suggest increased prevalence of food allergy. However, relatively little is known about its pathogenesis. This review aims to assess temporal trends in the prevalence of food allergy and discuss potential genetic, environmental, and demographic determinants. The search strategy examined the medical literature database MEDLINE (using PubMed) for the time period of January 1, 2002 to January 31, 2012. In recent decades, the prevalence of food allergy in general has increased by 0.60 % [95 % confidence interval (CI), 0.59 %-0.61 %] and the prevalence of peanut allergy by 0.027 % (95 % CI, 0.026 %-0.028 %), but it has now likely stabilized in developed countries. Genes, the environment, and demographic characteristics play a role in the pathogenesis of food allergy. Numerous environmental and demographic factors as well as gene-environment interactions may account for this increase in prevalence, but further studies are required to tease out their relative contribution.

Role of NOD1-mediated signals in a mouse model of allergic rhinitis

OBJECTIVES

The purpose of the present study was to investigate the effect of nucleotide-binding oligomerization domain 1 (NOD1), an innate immune sensor, on allergic inflammation and induction of regulatory T cells in a mouse model of allergic rhinitis. We also aimed to explore whether there were differences in the effect of NOD1 ligand according to the timing of administration. Study Design An in vivo study using an animal model.

SETTING

Catholic Research Institutes of Medical Science.

SUBJECTS AND METHODS

Forty BALB/c mice were divided into 4 groups: control, OVA, pre-NOD1, and post-NOD1. Ovalbumin (OVA) was used for sensitization and challenge. The pre-NOD1 group received NOD1 ligand intranasally before sensitization, whereas the post-NOD1 group received it after sensitization. The effects of allergic inflammation and regulatory T cells were compared among the groups.

RESULTS

In the post-NOD1 group, serum OVA-specific IgE, eosinophil counts, interleukin (IL)-13 levels, and GATA-3 mRNA expression were significantly increased and Foxp3(+) mRNA expression and CD4(+) Foxp3(+) T cells were decreased compared with the OVA group. In the pre-NOD1 group, Foxp3 mRNA expression and CD4(+) Foxp3(+) T cells were significantly decreased compared with the OVA group. Although not significant, the pre-NOD1 group showed increases in serum OVA-specific IgE, eosinophil counts, IL-13 levels, and GATA-3 mRNA expression compared with the OVA group.

CONCLUSION

The innate immune response through NOD1 enhances allergen-specific Th2 response and suppresses induction of regulatory T cells in a mouse model of allergic rhinitis, and the effects are different depending on the timing of exposure to NOD1 ligand.

Does treatment of the laryngeal mucosa reduce dystonic symptoms? A prospective clinical cohort study of mannose binding lectin and other immunological parameters with diagnostic use of phonatory function studies

This study examined efficacy of the innate immune defence via the mannose binding lectin (MBL) in a cohort of 55 dystonic patients prospectively referred to the clinic with laryngeal mucosal complaints, who were placed on local steroids (budesonid inhaler, 400 μg 2 times daily) and antihistamines (fexofenadin 180 mg mostly 3 times daily) with adjuvant lifestyle corrections. Treatment efficacy of the larynx was assessed based on mucosal findings of the vocal folds examined with phonatory function studies (PhFS) comprising simultaneous high-speed digital images, kymography, electroglottography and voice acoustics combined with a visual score of arytenoids oedema, as these measures are indicative of the magnitude of laryngitis. Lactose and gluten intolerance and immunological analyses of the innate system were made systematically. Results showed that the genetic aspects of immunology did not reveal a role for the innate immune system, represented by the MBL. But an unexpected positive effect of the larynx treatment on dystonia symptoms was found evidenced by reduction of dystonic complaints and more normative results of PhFS, and a reduction of oedema of the inter arytenoids region. Symptoms relieve and better quality of life was observed on follow-up for the dystonia complaints.

Glucocorticoid-induced leucine zipper is downregulated in human alveolar macrophages upon Toll-like receptor activation

Induction of the glucocorticoid-induced leucine zipper (GILZ) by glucocorticoids plays a role in their antiinflammatory action, whereas GILZ expression is reduced under inflammatory conditions. The mechanisms regulating GILZ expression during inflammation, however, have not yet been characterized. Here, we investigated GILZ expression in human alveolar macrophages (AMs) following Toll-like receptor (TLR) activation. Macrophages were shown to predominantly express GILZ transcript variant 2. Lipopolysaccharide-treated AMs, THP-1 cells, and lungs of lipopolysaccharide-exposed mice displayed decreased GILZ protein and mRNA levels. The effect was strictly dependent on the adapter molecule MyD88, as shown by using specific ligands or a knockdown strategy. Investigations on the functional significance of GILZ downregulation performed by GILZ knockdown revealed a proinflammatory response, as indicated by increased cytokine expression and NF-κB activity. We found that TLR activation reduced GILZ mRNA stability, which was mediated via the GILZ 3'-untranslated region. Finally, involvement of the mRNA-binding protein tristetraprolin (TTP) is suggested, since TTP overexpression or knockdown modulated GILZ expression and TTP was induced in a MyD88-dependent fashion. Taken together, our data show a MyD88- and TTP-dependent GILZ downreg-ulation in human macrophages upon TLR activation. Suppression of GILZ is mediated by mRNA destabilization, which might represent a regulatory mechanism in macrophage activation.

Disturbed cytokine production at the systemic level in difficult-to-control atopic asthma: evidence for raised interleukin-4 and decreased interferon-γ release following lipopolysaccharide stimulation

BACKGROUND

Disturbed cytokine production is thought to govern inflammation in asthma, which, in its turn, may lead to uncontrolled disease. The aim of this study was to assess the relationship between cytokine production from blood leucocytes and the level of asthma control.

METHODS

We compared the production of interleukin (IL)-4, IL-6, IL-10, interferon (IFN)-γ and tumour necrosis factor-α from peripheral blood leucocytes in non-atopic healthy subjects (n = 22), atopic non-asthmatics (n = 10), well-controlled asthmatics [Juniper asthma control questionnaire (ACQ) score <1.5; n = 20] and patients with uncontrolled asthma despite inhaled or oral corticoids (ACQ score ≥1.5; n = 20). Fifty microlitres of peripheral blood was incubated for 24 h with RPMIc, lipopolysaccharide (LPS; 1 ng/ml) or phytohaemagglutinin (1 μg/ml), and cytokines were measured by immunotrapping (ELISA).

RESULTS

Both controlled and uncontrolled asthmatics as well as atopic non-asthmatics spontaneously produced more IL-4 than non-atopic healthy subjects (p < 0.001). IL-4 production induced by LPS was significantly greater (p < 0.05) in both asthma groups compared to atopic non-asthmatics and non-atopic healthy subjects. By contrast, IFN-γ release induced by LPS was lower in uncontrolled asthmatics than in non-atopic healthy subjects (p < 0.05) and controlled asthmatics (p < 0.05). IL-10 release after LPS was greater in uncontrolled asthmatics than in atopic non-asthmatics (p < 0.05). No difference was observed regarding other cytokines.

CONCLUSION

Blood cells from patients with difficult-to-control atopic asthma display highly skewed Th2 cytokine release following LPS stimulation.

Allergic rhinitis and genetic components: focus on Toll-like receptors (TLRs) gene polymorphism

Allergic rhinitis represents a global health issue affecting 10% to 25% of the population worldwide. Over the years, studies have found that allergic diseases, including allergic rhinitis, are associated with immunological responses to antigens driven by a Th2-mediated immune response. Because Toll-like receptors (TLRs) are involved in both innate and adaptive immune responses to a broad variety of antigens, the association between polymorphisms of TLRs and allergic diseases has been the focus in many animal and human studies. Although the etiology of allergic rhinitis is still unknown, extensive research over the years has confirmed that the underlying causes of allergic diseases are due to many genetic and environmental factors, along with the interactions among them, which include gene-environment, gene-gene, and environment-environment interactions. Currently, there is great inconsistency among studies mainly due to differences in genetic background and unique gene-environment interactions. This paper reviews studies focusing on the association between TLR polymorphisms and allergic diseases, including allergic rhinitis, which would help researchers better understand the role of TLR polymorphisms in the development of allergic rhinitis, and ultimately lead to more efficient therapeutic interventions being developed.

Cancer inflammation and regulatory T cells

Chronic inflammation is essential for cancer growth and metastasis. It follows that factors reducing inflammation would abrogate cancer and restore tissue health. However, roles for anti-inflammatory CD4+ regulatory cells (T(REG)) in cancer are enigmatic and controversial. Our recent data reveal that T(REG) may function in cancer similarly to inflammatory bowel disease or multiple sclerosis, whereby T(REG) accumulate but lack potency to restore tissue homeostasis under inflammatory conditions. Interestingly, early life exposures to diverse environmental organisms reinforce a protective T(REG) phenotype that inhibits cancer. In contrast, hygienic individuals with few exposures earlier in life suffer from a dysregulated T(REG) feedback loop. Consequently, hygienic subjects have increased risk of malignancy later in life. This cancer condition is reversible by blocking underlying inflammation. Taken together, these data help explain increased inflammation-associated cancer rates in hygienic societies and identify targets to abrogate cancer and restore overall health.

Siglec-E is up-regulated and phosphorylated following lipopolysaccharide stimulation in order to limit TLR-driven cytokine production

Although production of cytokines by TLR is essential for viral and bacterial clearance, overproduction can be detrimental, thus controlling these responses is essential. CD33-related sialic acid binding Ig-like lectin receptors (Siglecs) have been implicated in the control of leukocyte responses. In this study, we report that murine Siglec-E is induced by TLRs in a MyD88-specific manner, is tyrosine phosphorylated following LPS stimulation, and negatively regulates TLR responses. Specifically, we demonstrate the Siglec-E expression inhibits TLR-induced NF-kappaB and more importantly, the induction of the antiviral cytokines IFN-beta and RANTES. Siglec-E mediates its inhibitory effects on TIR domain containing adaptor inducing IFN-beta (TRIF)-dependent cytokine production via recruitment of the tyrosine [corrected] phosphatase SHP2 and subsequent inhibition of TBK1 activity as evidenced by enhanced TBK1 phosphorylation in cells following knockdown of Siglec-E expression. Taken together, our results demonstrate a novel role for Siglec-E in controlling the antiviral response to TLRs and thus helping to maintain a healthy cytokine balance following infection.

Soluble immune receptor serum levels are associated with age, but not with clinical phenotype or disease severity in childhood atopic dermatitis

BACKGROUND

Soluble immune receptors (SIRs) have been proposed as biomarkers in patients with atopic dermatitis (AD). However, their clinical applicability in affected children has rarely been studied.

OBJECTIVE

To assess the diagnostic usefulness of serum SIRs in childhood AD by correlating the obtained receptor profiles with serological parameters and clinical features such as age, AD phenotype and disease severity.

METHODS

We investigated 100 children with AD. The sCD14, sCD23, sCD25, sCD30, total IgE (tIgE) and eosinophilic cationic protein (ECP) were determined using sera of all children. The clinical phenotype was classified as extrinsic AD (ADe) or intrinsic AD (ADi) by the presence of allergen-specific IgE antibodies.

RESULTS

A total of 55 male and 45 female children were recruited. The sCD23, sCD25 and sCD30 serum levels revealed significant age-dependency. At a mean SCORAD of 40 (range 8-98), none of the evaluated SIRs was correlated to disease severity. In all, 73% of patients suffered from ADe while 27% showed the ADi phenotype. None of the analysed SIRs differed significantly between ADe and ADi patients, while tIgE and ECP levels were elevated in the ADe subgroup.

CONCLUSION

The current study provides evidence that sCD23, sCD25 and sCD30 serum levels are highly age-dependent. Serum concentrations of all investigated SIRs did not significantly correlate with disease severity in children with AD and were not differentially expressed in patients of different AD phenotypes. Therefore, we believe that the studied SIRs cannot be regarded as clinically useful biomarkers for the assessment of childhood AD.