IgE response to staphylococcal enterotoxins in adenoid tissues from atopic children

Superantigens, a Paradox of the Immune Response

Staphylococcal enterotoxins are a wide family of bacterial exotoxins with the capacity to activate as much as 20% of the host T cells, which is why they were called superantigens. Superantigens (SAgs) can cause multiple diseases in humans and cattle, ranging from mild to life-threatening infections. Almost all S. aureus isolates encode at least one of these toxins, though there is no complete knowledge about how their production is triggered. One of the main problems with the available evidence for these toxins is that most studies have been conducted with a few superantigens; however, the resulting characteristics are attributed to the whole group. Although these toxins share homology and a two-domain structure organization, the similarity ratio varies from 20 to 89% among different SAgs, implying wide heterogeneity. Furthermore, every attempt to structurally classify these proteins has failed to answer differential biological functionalities. Taking these concerns into account, it might not be appropriate to extrapolate all the information that is currently available to every staphylococcal SAg. Here, we aimed to gather the available information about all staphylococcal SAgs, considering their functions and pathogenicity, their ability to interact with the immune system as well as their capacity to be used as immunotherapeutic agents, resembling the two faces of Dr. Jekyll and Mr. Hyde.

The histological and microbiological characteristics of bacterial microcolonies in paediatric tonsillar hyperplasia

INTRODUCTION

Paediatric tonsillar hyperplasia (TH) is associated with a spectrum of presentations ranging from recurrent tonsillitis (RT) to sleep-disordered breathing (SDB). The underlying pathogenesis of tonsillar hyperplasia remains poorly understood. Previous studies have implicated bacterial microcolonies as targets of host inflammatory cells and as a potential driver of the chronic inflammation seen in TH. The role of atopy in tonsillar hyperplasia is also largely unknown. In this study, we aimed to determine the allergic responses and microbial factors that may influence TH in children.

MATERIALS AND METHODS

Paired tonsils and a serum sample were collected from 21 children undergoing tonsillectomy for RT or SDB in the Auckland region. The disposition of immunoglobulin isotypes (IgG, A, M and E) and local inflammatory cells on histological sections of tonsil tissue were determined using immunohistochemistry techniques. Aeroallergen specific IgE (sIgE) and Staphylococcal enterotoxin C specific IgE (SEC-specific IgE) were measured in serum and tonsil tissue using the ImmunoCAP® system. Finally, tonsil bacterial microcolonies were then excised from histological slides using laser microdissection techniques, before undergoing bacterial and fungal amplicon sequencing.

RESULTS

There were no significant differences in any of the measured variables between children with RT and SDB symptoms. IgE staining was not associated with increased levels of mast cells, leukocytes or plasma cells. However, sIgE positivity was more frequently found in local tissue than in serum (p = 0.025). A significant association was observed between tissue sIgE levels and tissue SEC-specific IgE levels (r² = 0.95, p = 0.0001). The most abundant bacterial and fungal genera identified in the microcolonies were Fusobacterium, Sphingomonas, Porphyromonas, Prevotella and Malassezia.

DISCUSSION

These results suggest that there is a local IgE response in children with TH. Local IgE production is unrelated to systemic atopy and may play a key role in the pathogenesis of TH. This is the first study to determine the microbial composition of microcolonies in tonsil tissue. These findings enhance current understanding of the microbiology of tonsils in children with TH and have important implications for antibiotic strategies.

Down-regulation of anti-inflammatory TIPE2 may aggravate adenoidal hypertrophy in children

Adenoidal hypertrophy (AH) is a common disorder in the pediatric population, with common symptoms including mouth breathing, nasal congestion, hyponasal speech, snoring and obstructive sleep apnea. Although the pathogenesis of AH has not been fully elucidated, recent studies have indicated that immune responses may play an important role in AH. Tumor necrosis factor‐alpha (TNF‐α)‐induced protein‐8 like‐2 (TIPE2) is a newly identified protein that negatively regulates the activation of inflammatory pathways. Here, we investigated the effect of TIPE2 in AH in children. We observed that the levels of TNF‐α and interleukin‐6 were greater in the adenoid tissue of AH children than in healthy control subjects (P < 0.01), and this increase was positively correlated with the severity of AH. The level of TIPE2 expression was decreased compared with control and was negatively correlated with AH. TIPE2 overexpression in primary human monocytes (isolated from adenoid tissue of children with AH) inhibited the activation of nuclear factor‐κB and the expression of TNF‐α and interleukin‐6. These results suggest that overexpression of TIPE2 may attenuate AH through inactivation of the nuclear factor‐κB signaling pathway.

Role of Superantigens in Allergic Inflammation: Their Relationship to Allergic Rhinitis, Chronic Rhinosinusitis, Asthma, and Atopic Dermatitis

OBJECTIVES

Our intention was to review all material published to date regarding superantigens (SAgs) and allergy from an otorhinolaryngological viewpoint to understand this association more clearly.

METHODS

We identified all materials published mentioning both SAg and allergic rhinitis (AR), chronic sinusitis, asthma, and atopic dermatitis (AD) that are indexed on PubMed, Google, or the ProQuest Central databases.

RESULTS

Staphylococcus aureus is a significant bacterial pathogen in humans and has the ability to produce enterotoxins with superantigenic features. The inflammatory response in allergy seen in both B cell and T cell may be attributed to SAgs. Sufferers of both allergic asthma with rhinitis and AR alone produce serological evidence of immunoglobulin E formation to SAgs produced by S. aureus. Perennial AR sufferers carry S. aureus more frequently and the presence of the organism within the nasal cavity may exacerbate perennial AR. SAg produced by S. aureus potentially worsens the asthmatic inflammatory response within the airway and may lead to the airways becoming hyperresponsive, as well as possibly activating T cells if asthmatic control is poor. Staphylococcal SAgs potentially increase the risk of developing chronic rhinosinusitis with nasal polyposis, additionally being a marker for more severe disease. If SAgs bring about chronic inflammatory responses in the nose and sinuses, then T cells excreting interferon-gamma may be a crucial mediator. In allergic dermatitis, S. aureus could be a key player in exacerbation of the condition. Even in younger pediatric patients with allergic dermatitis, allergic hypersensitivity to SAgs is frequent and may be a factor explaining how severe the condition becomes.

CONCLUSION

Just as SAgs are known to feature in many allergic conditions, they play their part in AR, chronic rhinosinusitis, asthma, and AD. Further research is required before the relationship between SAgs and allergy can be adequately explained.

Long-term effects of adenotonsillectomy on serum-specific immunoglobulin E

BackgroundThe biased immune reactions of the adenotonsillar tissues are not always reflected by the serum immunoglobulin E (IgE); thus, we hypothesize that the systemic atopic status may not be changed after the adenotonsillectomy (AT) in children.MethodsTwenty-five children with AT and 23 age-matched healthy children were enrolled into this study, and followed up for ~4 years. Nasal Symptoms Scores (NSS), Quality of Life Scores (QOLS), specific IgE (sIgE), cytokines, and inflammatory cell were documented in all the subjects before and after study.ResultsFourteen patients and three healthy controls had positive serum sIgE levels (>0.35 kU/l) at the study-start that was not changed by the study-end. Two patients and two sIgE-negative healthy controls showed the Dermatophagoidespteronyssinus sensitization at the study-end. NSS and QOLS showed significant improvement after the surgery in the sIgE-positive patients (P<0.05), whereas no significant changes were found in the sIgE-negative patients (P=1.00). In addition, the serum sIgE-negative patients showed significant increases in interleukin (IL)-4, IL-5, and IL-10 levels in the serum (P<0.001), although no significant differences were found post surgery (P=0.667, 0.408, and 0.714, respectively).ConclusionsOur study showed that AT did not affect the pediatric atopic status. The systemic atopy may be independent of the tonsillar and adenoid tissues in children.

Allergens, germs and asthma

Objective

To explore asthma pathogenesis using data from upper and lower airways.

Data Source

English-language papers on human asthma and nasal polyp subjects from 1990 onwards.

Study Selection

High-quality studies in established journals.

Results

The recognition of its inflammatory nature led to a quantum leap in the understanding and treatment of asthma, with lives saved by inhaled corticosteroids. Further work at genetic, molecular, histological and clinical levels has shown that asthma is polymorphic and rarely involves isolated Th2 bronchial inflammation.

Viral infections may act as an initiating event in children and adults, showing synergy with atopy. Chronic staphylococcal colonization of the mucosa may act as a promoter, as in atopic dermatitis. These two observations may be linked, with viruses providing an entry for bacteria into the mucosal epithelium.

Conclusions

Most asthma begins in the nose and involves allergy and infection: both viral and bacterial. The combination of atopy and infection suggests new possibilities for therapy.

Paediatric rhinitis: position paper of the European Academy of Allergy and Clinical Immunology

Rhinitis is a common problem in childhood and adolescence and impacts negatively on physical, social and psychological well-being. This position paper, prepared by the European Academy of Allergy and Clinical Immunology Taskforce on Rhinitis in Children, aims to provide evidence-based recommendations for the diagnosis and therapy of paediatric rhinitis. Rhinitis is characterized by at least two nasal symptoms: rhinorrhoea, blockage, sneezing or itching. It is classified as allergic rhinitis, infectious rhinitis and nonallergic, noninfectious rhinitis. Similar symptoms may occur with other conditions such as adenoidal hypertrophy, septal deviation and nasal polyps. Examination by anterior rhinoscopy and allergy tests may help to substantiate a diagnosis of allergic rhinitis. Avoidance of relevant allergens may be helpful for allergic rhinitis (AR). Oral and intranasal antihistamines and nasal corticosteroids are both appropriate for first-line AR treatment although the latter are more effective. Once-daily forms of corticosteroids are preferred given their improved safety profile. Potentially useful add-on therapies for AR include oral leukotriene receptor antagonists, short bursts of a nasal decongestant, saline douches and nasal anticholinergics. Allergen-specific immunotherapy is helpful in IgE-mediated AR and may prevent the progression of allergic disease. There are still a number of areas that need to be clarified in the management of rhinitis in children and adolescents.

Detection of Staphylococcal Exotoxins in Antrochoanal Polyps and Chronic Rhinosinusitis with Nasal Polyps

Objective

Staphylococcal exotoxins have been reported in the pathogenesis of many chronic inflammatory diseases. Recent reports have hypothesized that staphylococcal exotoxins might be related to inflammatory mucosal changes seen in chronic sinusitis with nasal polyps (CRS-NPs). Staphylococcal exotoxins have the capacity to act as superantigens (SAgs), bypassing normal antigen processing and directly stimulating a massive inflammatory response. The objective of this study was to analyze polyp tissue samples from patients with antrochoanal polyps (ACPs) and CRS-NPs for the presence of staphylococcal exotoxins.

Study Design

Prospective cohort study.

Setting

Tertiary medical center.

Subjects and Methods

Tissue samples were obtained from 29 patients and 16 controls. Thirteen of 29 patients had ACPs, and 16 had CRS-NPs. Specimens were analyzed for the presence of 5 staphylococcal exotoxins (SEA, SEB, SEC, SED, and toxic shock syndrome toxin–1) using enzyme-linked immunosorbent assay (ELISA).

Results

At least 1 toxin was detected in 7 of 13 patients with ACPs and in 13 of 16 patients with CRS-NPs, whereas it was detected in only 4 controls. There were no statistically significant differences between ACP and control groups ( P = .063). Our results showed a statistically significant association between toxin detection and patients with CRS-NPs ( P = .003).

Conclusion

Inflammatory triggers in ACP remain a subject of debate, and this study does not support the hypothesis that staphylococcal exotoxins may play a role in ACP ethiopathogenesis. Our research is consistent with the possibility of SAgs as etiological agents in the development of bilateral nasal polyposis.

Local IgE-mediated hypersensitivity to Alternaria in pediatric adenoid tissue

OBJECTIVE

Fungus may contribute to the development and exacerbation of allergic airway diseases. Several studies have demonstrated the presence of humoral immune responses to fungi, including Alternaria and Aspergillus, in patients with nasal polyposis, asthma, or rhinitis. The purpose of this study was to evaluate the role of Alternaria- and Aspergillus-specific IgE antibodies in allergic inflammation of adenoid tissue.

METHODS

Thirty-nine atopic subjects who were sensitized to more than one common aeroallergen and 39 non-atopic subjects undergoing adenotonsillectomy were recruited. The Phadia ImmunoCAP was used to quantify total IgE, Alternaria- and Aspergillus-specific IgE, eosinophil cationic protein (ECP), and mast cell tryptase in adenoid tissue homogenates. Alternaria- and Aspergillus-specific IgE were detected in the adenoid tissues from some of the subjects (37.2% and 24.4%, respectively) without systemic sensitization to common airborne fungi.

RESULTS

Both Alternaria- and Aspergillus-specific IgE were more prevalent in adenoid tissues from atopic children (48.7% and 38.5%, respectively) than in tissues from non-atopic children (25.6% and 10.3%, respectively). Subjects with high Alternaria-specific IgE level showed significantly higher serum and adenoid total IgE and adenoid ECP and tryptase than those without specific IgE. Alternaria-specific IgE levels were significantly correlated with serum and adenoid total IgE and with tryptase and ECP levels in adenoid tissue.

CONCLUSIONS

Adenoid tissues from atopic and non-atopic children displayed local IgE-mediated hypersensitivity to fungi in the absence of systemic fungal hypersensitivity. Locally-produced Alternaria-specific IgE may contribute to mast cell and eosinophil activation, especially in the presence of tissue eosinophilia.

IL-5 Promoter Polymorphism Enhances IgE Responses to Staphylococcal Superantigens in Adult Asthmatics

Interleukin 5 (IL-5) is a key cytokine involved in the induction of T-helper type 2 (Th2) responses in the asthmatic airway. We investigated IL-5 genetic polymorphisms associated with asthma phenotypes, including IgE responses to staphylococcal enterotoxins A and B (SEA and SEB, respectively), in asthmatics. Adult asthmatics (n=310) and normal controls (n=160) were enrolled in the present study. Serum total and specific IgE to SEA and SEB were measured. Two IL-5 polymorphisms, -746A>G and +4499T>G, were genotyped using the primer-extension method. There were no significant differences in genotype or haplotype frequencies of these polymorphisms between the two groups. Asthmatics carrying the AG/GG genotype at -746A>G had a significantly higher prevalence of serum specific IgE to SEA (P=0.008), higher total IgE levels (P=0.014), and lower PC20 methacholine levels (P=0.002) compared to those with the AA genotype. These findings suggest that the IL-5 promoter polymorphism at -746A>G enhances serum total and specific IgE responses to SEA, which may augment airway hyperresponsiveness in adult asthmatics.

Staphylococci and staphylococcal superantigens in asthma and rhinitis: a systematic review and meta-analysis

BACKGROUND

There is a need for new treatment options of allergic respiratory diseases based on a better knowledge of their pathogenesis. An association between bacterial products and allergic airway diseases has been suggested by the results of human and animal studies that describe a link between Staphylococcus aureus enterotoxins and atopic diseases. The aim of the systematic review is to assess the evidence for a role of Staphylococcus aureus enterotoxins, as an environmental risk factor, for the development and/or the severity of asthma and allergic rhinitis.

METHODS

We performed a systematic review of controlled clinical studies in adults and/or children affected by asthma/early wheeze and/or allergic rhinitis. To be eligible, studies had to use reproducible methods to provide evidence of exposure to S. aureus, clinical outcome and disease severity.

RESULTS

Ten studies, published between 2000 and 2007, fulfilled all eligibility criteria. Patients with asthma or allergic rhinitis showed an increased prevalence of positivity for measures of exposure to S. aureus in nine studies: differences were statistically significant (P < 0.05) in seven studies. In a meta-analysis of study results, patients with asthma were more likely than controls to have serum-specific IgE to Staphylococcus aureus enterotoxins (OR = 3.3, 95% CI: 1.6-7.1, P = 0.002); similarly, patients with allergic rhinitis were more likely than controls to test positive for local or systemic exposure to Staphylococcus aureus and/or or its enterotoxins (OR = 2.4, 95% CI: 1.3-4.7, P = 0.008).

CONCLUSIONS

A potential role of S. aureus superantigens in allergic respiratory diseases is supported by results of this meta-analysis of clinical studies.