Aggravation of bronchial eosinophilia in mice by nasal and bronchial exposure to Staphylococcus aureus enterotoxin B

The Role of Staphylococcus aureus and Its Toxins in the Pathogenesis of Allergic Asthma

Bronchial asthma is one of the most common chronic diseases worldwide and affects more than 300 million patients. Allergic asthma affects the majority of asthmatic children as well as approximately 50% of adult asthmatics. It is characterized by a Th2-mediated immune response against aeroallergens. Many aspects of the overall pathophysiology are known, while the underlying mechanisms and predisposing factors remain largely elusive today. Over the last decade, respiratory colonization with Staphylococcus aureus (S. aureus), a Gram-positive facultative bacterial pathogen, came into focus as a risk factor for the development of atopic respiratory diseases. More than 30% of the world’s population is constantly colonized with S. aureus in their nasopharynx. This colonization is mostly asymptomatic, but in immunocompromised patients, it can lead to serious complications including pneumonia, sepsis, or even death. S. aureus is known for its ability to produce a wide range of proteins including toxins, serine-protease-like proteins, and protein A. In this review, we provide an overview of the current knowledge about the pathophysiology of allergic asthma and to what extent it can be affected by different toxins produced by S. aureus. Intensifying this knowledge might lead to new preventive strategies for atopic respiratory diseases.

Cellular immune response of Staphylococcus aureus enterotoxin B in Balb/c mice through intranasal infection

Background and Aim:

Staphylococcus aureus produces various superantigen exotoxins, including staphylococcal enterotoxin B (SEB). It causes fatal anaphylactic reactions and toxic shock. This study aimed to evaluate the reaction of leukocytes and histopathological changes in the respiratory organs of Balb/c mice after intranasal infection with enterotoxigenic S. aureus (SEB).

Materials and Methods:

The presence of the seb gene in S. aureus was established in this study using polymerase chain reaction-specific primer. Two groups of 8-week-old male Balb-c mice consist of six mice in each group. The treated group was infected with 50 μL and 100 μL of SEB intranasal on days 1 and 14, respectively. NaCl was administered in the second group and was considered as a control group. Blood samples were collected through the retro-orbital plexus on days 1, 4, 7, 14, and 22 after infections. Total cell counts were analyzed with an independent sample t-test and compared using the statistical package for the social sciences (SPSS) version 16.0 (IBM Corp., NY, USA). The infected tissues of the respiratory organ were observed descriptively and compared to the control group.

Results:

The seb gene with a molecular size of 478 bp, indicating the SEB strain, is present in S. aureus used in this study. Intranasal administration of SEB showed increased leukocytes, lymphocytes, monocytes, and eosinophils on day 22 post-infection. Significant leukocytosis was seen on days 6 and 14; lymphocytosis on days 1, 4, 6, and 16; and eosinophilia on days 6, 14, and 22 compared with the control group (p > 0.05). In contrast, the neutrophil decreased after an increase of immature band cells compared to the control group, indicating a severe acute infection with SEB. The lungs and trachea of the test group had an inflammatory cell accumulation in the respiratory organ.

Conclusion:

Intranasal route infection of S. aureus containing seb gene significantly induced the cellular immune response and caused pathological changes in the respiratory tissues of the Balb/c mice model. The hematological changes were aligned with marked pathological changes in the respiratory tract. Balb/c mice could be an excellent experimental model to study toxic and anaphylactic shock against SEB to define the future therapeutic agents.

Exploring the Role of Staphylococcus aureus in Inflammatory Diseases

Staphylococcus aureus is a very common Gram-positive bacterium, and S. aureus infections play an extremely important role in a variety of diseases. This paper describes the types of virulence factors involved, the inflammatory cells activated, the process of host cell death, and the associated diseases caused by S. aureus. S. aureus can secrete a variety of enterotoxins and other toxins to trigger inflammatory responses and activate inflammatory cells, such as keratinocytes, helper T cells, innate lymphoid cells, macrophages, dendritic cells, mast cells, neutrophils, eosinophils, and basophils. Activated inflammatory cells can express various cytokines and induce an inflammatory response. S. aureus can also induce host cell death through pyroptosis, apoptosis, necroptosis, autophagy, etc. This article discusses S. aureus and MRSA (methicillin-resistant S. aureus) in atopic dermatitis, psoriasis, pulmonary cystic fibrosis, allergic asthma, food poisoning, sarcoidosis, multiple sclerosis, and osteomyelitis. Summarizing the pathogenic mechanism of Staphylococcus aureus provides a basis for the targeted treatment of Staphylococcus aureus infection.

Potent Anti-Inflammatory Effects of Tetracyclines on Human Eosinophils

Eosinophils are potent pro-inflammatory cells. Not only in allergic diseases but also in other diseases there is a need for treatment strategies to induce resolution of eosinophil-mediated inflammation. During the last years beneficial non-antibiotic activities of tetracyclines (TCNs) have been shown in different diseases in which eosinophils play a role, for example, asthma and bullous pemphigoid. The working mechanism of these effects remains to be clarified. Aim of the present study was to investigate the effects of TCNs on eosinophils. Flow cytometry analysis of apoptosis, mitochondrial membrane potential, activation of caspases, intracellular H₂O₂ and calcium, surface expression of eosinophil activation markers was performed in highly purified peripheral blood eosinophils of non-atopic donors. Tetracycline hydrochloride, minocycline and doxycycline significantly induced eosinophil apoptosis. All TCNs were able to significantly overcome the strong survival enhancing effects of pro-eosinophilic cytokines and staphylococcus aureus enterotoxins. Tetracycline hydrochloride induced eosinophil apoptosis was accompanied by intracellular production of hydrogen peroxide, loss of mitochondrial membrane potential and activation of caspases. Moreover, tetracycline hydrochloride significantly down regulated eosinophil surface expression of CD9 and CD45, and of the activation markers CD11b and CD69, but not of CD54, CD63, or CD95. Our data, propably for the first time, point to a potent anti-inflammatory role of TCNs on eosinophils.

Moulds and Staphylococcus aureus enterotoxins are relevant allergens to affect Type 2 inflammation and clinical outcomes in chronic rhinosinusitis patients

Background

Sensitisation to moulds and Staphylococcus aureus enterotoxins (SEs) is associated with the pathophysiology of both asthma and chronic rhinosinusitis (CRS). The purpose of this study was to clarify the contribution of sensitisation to these allergens to Type 2 inflammation in the blood, nose and the lower airways, and clinical outcomes in CRS patients.

Methods

We prospectively enrolled 56 CRS patients who underwent endoscopic sinus surgery (ESS) (20 with comorbid asthma) and 28 healthy controls between October 2015 and December 2017. CRS patients were followed up for 12 months after surgery. Type 2 inflammation-related biomarkers were analysed using blood, resected tissue samples and sputum. 10 allergens including Alternaria, Aspergillus and SEs were measured. Type 2 inflammation-related biomarkers and clinical outcomes were compared in the stratification with the presence or absence of allergen sensitisation.

Results

Sensitisation rate to moulds and SEs in asthmatic patients was increased when changing the cut-off value of specific IgE titre from 0.35 UA·mL⁻¹ to 0.10 UA·mL⁻¹ (1.7- and 4.5-fold, respectively). Moulds and SEs affected the prevalence of asthma and eosinophilic CRS by interacting with each other. All Type 2 inflammation-related biomarkers except for eosinophils in sinus tissue were significantly higher in patients with mould or SE (mould/SE) sensitisation (≥0.10 UA·mL⁻¹) (n=19) than in those without (n=37) and healthy subjects (all p<0.05). Meanwhile, mould/SE sensitisation did not affect longitudinal changes in clinical outcomes after ESS. Changes in serum mould/SE-IgE levels after ESS remained unclear.

Conclusion

Mould/SE sensitisation (≥0.10 UA·mL⁻¹) may affect the development of Type 2 inflammation and clinical outcomes in CRS patients.

Alternaria,Aspergillusand S. aureus enterotoxins are important allergens affecting Type 2 inflammation and clinical outcomes in CRS patients. Sensitisation to moulds/SEs (≥0.10 UA·mL⁻¹) would be meaningful in the pathophysiology of CRS.https://bit.ly/3bUG8ZT

Airways exposure of bacterial superantigen SEB enhances bone marrow eosinophil population and facilitates its egress to blood and lung tissue

BACKGROUND

Differentiation of bone marrow eosinophils (BM-EO) and its trafficking to peripheral blood and respiratory mucosa are a hallmark of inflammatory diseases. Staphylococcal enterotoxin B (SEB) has been shown to aggravate airways eosinophilic inflammation. This study aimed to investigate the effects of mouse airways SEB exposure on BM-EO population, as well as its adhesive properties and release of cytokines/chemokines that orchestrate BM-EO trafficking to lungs.

METHODS

Male BALB/c mice were intranasally exposed to SEB (1 μg), and at 4, 16, 24 and 48 h thereafter, bone marrow (BM), circulating blood and bronchoalveolar lavage (BAL) fluid were collected. Levels of cytokines/chemokines and expressions of VLA-4 and CCR3 in BM were evaluated. Adhesion of BM to ICAM-1 and VCAM-1 were also evaluated.

RESULTS

SEB exposure promoted a marked eosinophil influx to BAL at 16 and 24 h after exposure, which was accompanied by significant increases in counts of immature (16 h) and mature (4 to 48 h) forms of eosinophil in BM, along with blood eosinophilia (16 h). In BM, higher levels of eotaxin, IL-5, IL-4, IL-3 and IL-7 were detected at 16 to 48 h. SEB also significantly increased CCR3 expression and calcium levels in BM-EO, and enhanced the cell adhesion to ICAM-1 (24 h) and ICAM-1 (48 h).

CONCLUSION

Airways SEB exposure increases the number of eosinophils in BM by mechanisms involving a network of cytokine and chemokine release, facilitating the BM-EO adhesion to ICAM-1 and VCAM-1 to gain access to the peripheral blood and lung tissues.

Modulation of Allergic Sensitization and Allergic Inflammation by Staphylococcus aureus Enterotoxin B in an Ovalbumin Mouse Model

The superantigen Staphylococcus aureus (S. aureus) enterotoxin B (SEB) has been proposed a central player in the associations between S. aureus nasal colonization and the development of allergic asthma. Previously, SEB has been shown to aggravate allergic sensitization and allergic airway inflammation (AAI) in experimental mouse models. Aiming at understanding the underlying immunological mechanisms, we tested the hypothesis that intranasal (i.n.) SEB-treatment divergently modulates AAI depending on the timing and intensity of the SEB-encounter. In an ovalbumin-mediated mouse model of AAI, we treated mice i.n. with 50 ng or 500 ng SEB either together with the allergic challenge or prior to the peripheral sensitization. We observed SEB to affect different hallmark parameters of AAI depending on the timing and the dose of treatment. SEB administered i.n. together with the allergic challenge significantly modulated respiratory leukocyte accumulation, intensified lymphocyte activation and, at the higher dose, induced a strong type-1 and pro-inflammatory cytokine response and alleviated airway hyperreactivity in AAI. SEB administered i.n. prior to the allergic sensitization at the lower dose significantly boosted the specific IgE response while administration of the higher dose led to a significantly reduced recruitment of immune cells, including eosinophils, to the respiratory tract and to a significantly dampened Th-2 cytokine response without inducing a Th-1 or pro-inflammatory response. We show a remarkably versatile potential for SEB to either aggravate or alleviate different parameters of allergic sensitization and AAI. Our study thereby not only highlights the complexity of the associations between S. aureus and allergic asthma but possibly even points at prophylactic and therapeutic pathways.

Efficacy of mepolizumab for patients with severe asthma and eosinophilic chronic rhinosinusitis

Background

Several major randomized control studies have demonstrated that mepolizumab, an anti-IL-5 monoclonal antibody, is effective for patients with severe eosinophilic asthma who show exacerbation or require systemic corticosteroid maintenance therapy. However, the predictive factors of the response to mepolizumab other than blood eosinophil count are unclear in clinical practice.

Objective

To elucidate the predictive factors of the response to mepolizumab for patients with severe eosinophilic asthma.

Methods

From July 2016 to December 2017, 28 patients with severe asthma received mepolizumab in our hospital. To determine the predictive factors, we retrospectively evaluated patient characteristics, comorbidities, biomarkers, pulmonary function, maintenance dose of systemic corticosteroids and number of exacerbations.

Results

The response rate to mepolizumab treatment was 70% (19/27; one pregnant woman was excluded from analysis). Compared with 11 patients without eosinophilic chronic rhinosinusitis (ECRS), 16 patients with ECRS showed significantly improved systemic corticosteroid-sparing effects [− 71.3 ± 37.0% vs − 10.7 ± 20.1%, P = 0.006], change from baseline FeNO [− 19 ± 57 (%) vs 30 ± 77 (%), P = 0.023] and symptoms [14 patients (88%) vs five patients (45%), P = 0.033]. ECRS was identified as a predictive factor of the response to mepolizumab in a multivariate logistic regression analysis [odds ratio = 22.5, 95% CI (1.5–336), P = 0.024]. Of the eight patients previously administered omalizumab, five responded to mepolizumab. Staphylococcus aureus enterotoxin B IgE results were negative in 80% of responders (P = 0.14).

Conclusion

Both groups showed improved symptom scores and a decreased number of exacerbations. Mepolizumab substantially improved the clinical variables of patients with eosinophilic asthma complicated with ECRS.

Staphylococcus aureus Induces a Mucosal Type 2 Immune Response via Epithelial Cell-derived Cytokines

RATIONALE

Chronic rhinosinusitis with nasal polyps is characterized by a T-helper cell type 2-skewed upper airway inflammation. Mucosal Staphylococcus aureus colonization is found in the majority of patients with nasal polyps. S. aureus is known to induce type 2 cytokine release via enterotoxins.

OBJECTIVES

To investigate the impact of non-enterotoxin-producing S. aureus on type 2 cytokine release.

METHODS

TSLP (thymic stromal lymphopoietin), IL-33, and type 2 cytokines were assessed in a human mucosal tissue model upon S. aureus infection.

MEASUREMENTS AND MAIN RESULTS

S. aureus exposure increased the expression of IL-33, TSLP, IL-5, and IL-13 in nasal polyp tissue, accompanied by elevated expression levels of TSLP and IL-33 receptors, predominantly on CD3⁺ T cells. S. aureus infection led to the release of TSLP, but not IL-33, IL-5, or IL-13, from healthy inferior turbinate tissue. In contrast, S. epidermidis did not induce any epithelial cell-derived cytokines in nasal polyp or healthy tissue. S. aureus infection also increased the release of IL-33 and TSLP in BEAS-2B epithelial cells, accompanied by activation of NF-κB (nuclear factor κB) pathways. Incubation with CU-CPT22, a specific Toll-like receptor 2 antagonist, significantly reduced the S. aureus-induced release of TSLP and IL-33, and the activity of the NF-κB signal in BEAS-2B cells.

CONCLUSIONS

This study demonstrates for the first time that S. aureus can directly induce epithelial cell-derived cytokine release via binding to Toll-like receptor 2, and may thereby propagate type 2 cytokine expression in nasal polyp tissue.

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.

Probiotics against airway allergy: host factors to consider

The worldwide prevalence of allergic diseases has drastically increased in the past decades. Recent studies underline the importance of microbial exposure for the development of a balanced immune system. Consequently, probiotic bacteria are emerging as a safe and natural strategy for allergy prevention and treatment. However, clinical probiotic intervention studies have so far yielded conflicting results. There is increasing awareness about the importance of host-associated factors that determine whether an individual will respond to a specific probiotic treatment, and it is therefore crucial to promote a knowledge-based instead of an empirical selection of promising probiotic strains and their administration regimen.In this Review, we summarize the insights from animal model studies of allergic disease, which reveal how host-related factors - such as genetic makeup, sex, age and microbiological status - can impact the outcomes of preventive or curative probiotic treatment. We explore why and how these factors can influence the results of probiotic studies and negatively impact the reproducibility in animal experiments. These same factors might profoundly influence the outcomes of human clinical trials, and can potentially explain the conflicting results from probiotic intervention studies. Therefore, we also link these host-related factors to human probiotic study outcomes in the context of airway allergies.

Pediatric rhinosinusitis and asthma

Both asthma and rhinosinusitis are complex and heterogeneous diseases and, importantly, they often coexist: these diseases can be concomitant in 35-65% of affected children, according to different studies. Thus, evaluating this comorbidity in the clinical practice should be paramount. In this review, we focused our discussion on the multiple pathophysiological aspects that may link rhinosinusitis and asthma in the pediatric population. Although rhinosinusitis may exacerbate asthma through several mechanisms occurring by contiguity, actually this aspect seems to be only one component of the complex interplay between upper and lower airways. In particular, the onset of an important and persistent Th2-driven inflammatory process dominated by eosinophils presence at one site of the airways, may release into the bloodstream several cytokines; in their turn, those can lead to the stimulation of the bone marrow, which may function as a systemic amplifier of such an eosinophilic inflammation.

MHC Class II Activation and Interferon-γ Mediate the Inhibition of Neutrophils and Eosinophils by Staphylococcal Enterotoxin Type A (SEA)

Staphylococcal enterotoxins are classified as superantigens that act by linking T-cell receptor with MHC class II molecules, which are expressed on classical antigen-presenting cells (APC). Evidence shows that MHC class II is also expressed in neutrophils and eosinophils. This study aimed to investigate the role of MHC class II and IFN-γ on chemotactic and adhesion properties of neutrophils and eosinophils after incubation with SEA. Bone marrow (BM) cells obtained from BALB/c mice were resuspended in culture medium, and incubated with SEA (3–30 ng/ml; 1–4 h), after which chemotaxis and adhesion were evaluated. Incubation with SEA significantly reduced the chemotactic and adhesive responses in BM neutrophils activated with IL-8 (200 ng/ml). Likewise, SEA significantly reduced the chemotactic and adhesive responses of BM eosinophils activated with eotaxin (300 ng/ml). The inhibitory effects of SEA on cell chemotaxis and adhesion were fully prevented by prior incubation with an anti-MHC class II blocking antibody (2 μg/ml). SEA also significantly reduced the intracellular Ca²⁺ levels in IL-8- and eotaxin-activated BM cells. No alterations of MAC-1, VLA4, and LFA-1α expressions were observed after SEA incubation. In addition, SEA elevated by 3.5-fold (P < 0.05) the INF-γ levels in BM cells. Incubation of BM leukocytes with IFN-γ (10 ng/ml, 2 h) reduced both neutrophil and eosinophil chemotaxis and adhesion, which were prevented by prior incubation with anti-MHC class II antibody (2 μg/ml). In conclusion, SEA inhibits neutrophil and eosinophil by MHC class II-dependent mechanism, which may be modulated by concomitant release of IFN-γ.

Sensitization to Staphylococcus aureus enterotoxins in smokers with asthma

BACKGROUND

Sensitization to Staphylococcus aureus enterotoxins (SEs) augments eosinophilic inflammation in asthma. Recent epidemiologic studies demonstrate that sensitization to SEs is increased in healthy smokers; however, there is no evidence on the association between sensitization to SEs and eosinophilic inflammation in smokers with asthma.

OBJECTIVE

To clarify the role of SEs on clinical indexes, including eosinophilic inflammation and lung function in smokers with asthma.

METHODS

The frequency of atopic sensitization to SEs was examined in adult patients with asthma. In current or ex-smokers with asthma, the association of sensitization to SEs with eosinophilic inflammation, airflow limitation, or treatment steps was determined. Clinical indexes were examined at the first visit, and treatment steps were assessed 6 months after enrollment.

RESULTS

Overall, 23 current smokers, 40 ex-smokers, and 118 never smokers with asthma were enrolled. The frequency of sensitization to SEs, but not to other aeroallergens, was significantly higher in current, ex-, and never smokers, in decreasing order. In current or ex-smokers with asthma, patients with sensitization to SEs exhibited higher serum levels of total and specific IgE to aeroallergens, higher blood eosinophil counts, greater airflow limitation, and more severe disease 6 months later than those without sensitization to SE. A longer smoking abstinence period was associated with serum specific IgE levels to SEs, and 3 years was the best cutoff of abstinence period to predict the absence of sensitization to SEs.

CONCLUSION

Sensitization to SEs is increased in smokers with asthma, and it may be a marker of eosinophilic inflammation and severe asthma in smokers with asthma.

TRIAL REGISTRATION

umin.ac.jp Identifier: UMIN000007818.

An inhibitor peptide of toll-like receptor 2 shows therapeutic potential for allergic conjunctivitis

Allergic conjunctivitis (AC) is an inflammatory disease of the conjunctiva, which is characterized by antigen challenge and toll-like receptor 2 (TLR2) activation. Here, a designed small peptide ZY12 was found to contain therapeutic potential in staphylococcal enterotoxin B (SEB)-induced AC model. ZY12 treatment showed the remission of clinical signs, plasma total IgE levels, number of mast cells and the proportion of degranulated mast cell in AC mice. Levels of Th2 cytokines (IL-4, IL-5, IL-13) in the lymph nodes or spleen were significantly decreased while those of Th1 cytokine (IFN-γ) were increased in ZY12 treated group, suggesting a protective role of ZY12 in AC by mediating the balance of Th1/Th2 cytokines. Importantly, ZY12 significantly inhibited TLR2 expression in conjunctival tissue. Combined its therapeutic effects with TLR2 inhibitory function, ZY12 might be an ideal candidate for the development of new therapeutic agent for allergic disease.

Pathophysiology of chronic rhinosinusitis, pharmaceutical therapy options

Research in immunology has brought great progress in knowledge of inflammatory processes in the last 2 decades, which also has an impact on the upper airways. Our understanding of the pathophysiology of chronic rhinosinusitis developed from a rather mechanistic point of view with a focus on narrow clefts and mucociliary clearance to the appreciation of a complex network of immunological pathways forming the basis of disease. We today differentiate various forms of inflammation, we start to understand complex immune-regulatory networks and the reasons for their failure, and have already developed innovative approaches for therapy for the most severely ill subjects. Due to this new knowledge in inflammation and remodeling processes within mucosal tissue, specifically on the key driving factors, new diagnostic tools and therapeutic approaches for chronic rhinosinusitis have developed; the differentiation of endotypes based on pathophysiological principles will be crucial for the use of innovative therapies, mostly humanized monoclonal antibodies. Several hundred of those antibodies are currently developed for various indications and will impact our specialty as well as pneumology to a great extent.

Association between specific IgE to Staphylococcus aureus enterotoxins A and B and asthma control

BACKGROUND

Recent studies have found that serum levels of Staphylococcus aureus enterotoxin (SE)-IgE are higher in patients with severe asthma compared with patients with nonsevere asthma. However, the association between SE-IgE and asthma control is not fully understood. Furthermore, SEA and SEB were the first reported SEs and subdivided into different groups. The influences of SEA-IgE and SEB-IgE on asthma control have not been elucidated.

OBJECTIVE

To determine the relevance of SEA- and SEB-IgE in patients with adult asthma and to investigate the association of SEA-IgE, SEB-IgE, and asthma control, respectively.

METHODS

The serum concentrations of SEA- and SEB-IgE in 172 adults with asthma were measured with a fluorescent enzyme immunoassay.

RESULTS

The prevalence of SEA- and SEB-IgE was 16.2% and 22.1%, respectively. Total IgE levels and the prevalence of atopic dermatitis were higher in SEA-IgE- and SEB-IgE-positive patients than in SEA-IgE- and SEB-IgE-negative patients, respectively; more SEA-IgE- and SEB-IgE-positive patients owned pets. Sensitization to SEA was associated with a younger mean age and a younger mean age at asthma onset. Multiple regression analysis indicated an association between total IgE levels and SEB-IgE. The prevalence of poorly uncontrolled asthma was significantly higher in SEA-IgE-positive patients than in SEA-IgE-negative patients. In addition, fractional exhaled nitric oxide levels were higher in SEA-IgE-positive patients than in SEA-IgE-negative patients. Logistic regression analysis also identified an association between SEA-IgE and poor asthma control.

CONCLUSION

Our findings indicate that sensitization to SE, in particular SEA rather than SEB, is associated with poor asthma control in adults with asthma.

Staphylococcal enterotoxin sensitization in a community-based population: a potential role in adult-onset asthma

BACKGROUND

Recent studies suggest that Staphylococcus aureus enterotoxin sensitization is a risk factor for asthma. However, there is a paucity of epidemiologic evidence on adult-onset asthma in community-based populations.

OBJECTIVE

We sought to evaluate the epidemiology and the clinical significance of staphylococcal enterotoxin sensitization in community-based adult populations.

METHODS

The present analyses were performed using the baseline data set of Korean adult population surveys, consisting of 1080 adults (mean age = 60.2 years) recruited from an urban and a rural community. Questionnaires, methacholine challenge tests, and allergen skin tests were performed for defining clinical phenotypes. Sera were analysed for total IgE and enterotoxin-specific IgE using ImmunoCAP.

RESULTS

Staphylococcal enterotoxin sensitization (≥ 0.35 kU/L) had a prevalence of 27.0%. Risk factors were identified as male sex, current smoking, advanced age (≥ 61 years), and inhalant allergen sensitization. Current asthma was mostly adult onset (≥ 18 years old) and showed independent associations with high enterotoxin-specific IgE levels in multivariate logistic regression tests. In multivariate linear regressions, staphylococcal enterotoxin-specific IgE level was identified as the major determinant factor for total IgE level.

CONCLUSIONS AND CLINICAL RELEVANCE

Staphylococcal enterotoxin sensitization was independently associated with adult-onset asthma in adult community populations. Strong correlations between the enterotoxin-specific IgE and total IgE levels support the clinical significance. The present findings warrant further studies for the precise roles of staphylococcal enterotoxin sensitization in the asthma pathogenesis.

Staphylococcus aureus enterotoxins A and B inhibit human and mice eosinophil chemotaxis and adhesion in vitro

Staphylococcus aureus aggravates the allergic eosinophilic inflammation. We hypothesized that Staphylococcus aureus-derived enterotoxins directly affect eosinophil functions. Therefore, this study investigated the effects of Staphylococcal enterotoxins A and B (SEA and SEB) on human and mice eosinophil chemotaxis and adhesion in vitro, focusing on p38 MAPK phosphorylation and intracellular Ca(2+) mobilization. Eosinophil chemotaxis was evaluated using a microchemotaxis chamber, whereas adhesion was performed in VCAM-1 and ICAM-1-coated plates. Measurement of p38 MAPK phosphorylation and intracellular Ca(2+) levels were monitored by flow cytometry and fluorogenic calcium-binding dye, respectively. Prior incubation (30 to 240 min) of human blood eosinophils with SEA (0.5 to 3 ng/ml) significantly reduced eotaxin-, PAF- and RANTES-induced chemotaxis (P<0.05). Likewise, SEB (1 ng/ml, 30 min) significantly reduced eotaxin-induced human eosinophil chemotaxis (P<0.05). The reduction of eotaxin-induced human eosinophil chemotaxis by SEA and SEB was prevented by anti-MHC monoclonal antibody (1 μg/ml). In addition, SEA and SEB nearly suppressed the eotaxin-induced human eosinophil adhesion in ICAM-1- and VCAM-1-coated plates. SEA and SEB prevented the increases of p38 MAPK phosphorylation and Ca(2+) levels in eotaxin-activated human eosinophils. In separate protocols, we evaluated the effects of SEA on chemotaxis and adhesion of eosinophils obtained from mice bone marrow. SEA (10 ng/ml) significantly reduced the eotaxin-induced chemotaxis along with cell adhesion to both ICAM-1 and VCAM-1-coated plates (P<0.05). In conclusion, the inhibition by SEA and SEB of eosinophil functions (chemotaxis and adhesion) are associated with reductions of p38 MAPK phosphorylation and intracellular Ca(2+) mobilization.

Sinusitis, Rhinitis, Asthma, and the Single Airway Hypothesis

The one airway, one disease hypothesis proposes that the upper and lower airways share the same physiology and histomorphology. Epidemiological clinical studies support a link between rhinosinusitis and asthma. The relationship can occur in both directions, with nasal allergen challenge leading to inflammatory changes in the lower airway and bronchoprovocation studies of the lower airway leading to inflammatory changes in the upper airway. In addition, both similarities and differences exist in the pathogenesis of nasal polyps and asthma. The mechanism for the connection between the upper and lower airways is a matter of great debate. It has been proposed that inflammatory changes in the lower airway may lead to systemic inflammatory effects that play a role in increased bronchial hyperresponsiveness. Similarly, lower airway inflammatory changes may affect nasal airway patency via systemic effects. Moreover, nasopharyngeal-bronchial reflexes may play a non-immunologic role in the interaction between the lower and upper airways. An example of the connection between the upper and lower airways is found in aspirin-exacerbated respiratory disease whereby leukotrienes play a role in the pathology of chronic rhinosinusitis with polyps and asthma. It is also been observed that the treatment of asthma is hindered by untreated rhinosinusitis.

Long-term results of endoscopic sinus surgery-oriented treatment for chronic rhinosinusitis with asthma

OBJECTIVES/HYPOTHESIS

The aims of this study were to evaluate the efficacy of functional endoscopic sinus surgery (FESS)-oriented multimodality treatment in chronic rhinosinusitis (CRS) patients with asthma and its impact on asthma.

STUDY DESIGN

Prospective, nonrandomized cohort.

METHODS

Twenty-seven CRS patients with asthma who underwent FESS with postoperative topical corticosteroid spray were evaluated preoperatively; 25 of them were evaluated 1 year and 3 years postoperatively. CRS was evaluated by visual analogue scale, clinical control of CRS, and objective measurement endoscopy Lund-Kennedy scores. Asthma was assessed by subjective asthma control test and asthma control level, also by objective antiasthma medication use and pulmonary function tests.

RESULTS

VAS scores of general symptoms (8.09 ± 0.87 preoperatively) were significantly improved at 1 year (2.94 ± 2.21) and 3 years (3.77 ± 2.16) postoperation (P = .000). No difference in these items was found between 1 year and 3 years (P = .463). Endoscopy Lund-Kennedy scores at 1 year (4.34 ± 3.09) and 3 years (5.80 ± 3.38) postoperatively were significantly better (9.33 ± 2.03 preoperatively, P = .000), and there was no difference between 1 year and 3 years of follow-up (P > .05). Significantly, asthma control level improved postoperatively (P = .025). However, antiasthma drug and pulmonary function showed no significant change postoperatively (P > .05).

CONCLUSIONS

FESS-oriented multimodality treatment improves CRS with asthma significantly and persistently. Asthma control level improved. Antiasthma medication use and pulmonary function remained stable.

Bacterial superinfection following lung inflammatory disorders

The lung environment is designed to prevent innate responses to harmless commensal microorganisms and environmental antigens. Features of an intact respiratory epithelium are critical to this process. A damaged or altered lung epithelial surface will therefore remove or alter the suppressive signals delivered to local innate immune cells, and inflammation ensues. Timely resolution of inflammation is important to prevent bystander tissue damage. However, if resolving pathways themselves are prolonged or repeated, they too can cause undesirable consequences, including bacterial superinfections, which we discuss here.

Role of staphylococcal superantigens in airway disease

Staphylococcus aureus is a common human pathogen, which is regularly part of the normal microflora found in the nose and skin. It represents a significant threat to human health, not in the least because of its capability to produce exotoxins, which have superantigenic properties. These exotoxins, in particular the staphylococcal enterotoxins (SEs), are known to be involved in the modulation and aggravation of airway inflammation. Indeed, recent studies show an important impact of SEs on the natural course of allergic rhinitis, nasal polyposis, asthma and COPD. This review outlines the current knowledge on the influence of SEs on airway inflammation. We highlight, in particular, the recent evidence on their role in asthma.

The adjuvant-like activity of staphylococcal enterotoxin B in a murine asthma model is independent of IL-1R signaling

BACKGROUND

Staphylococcal enterotoxin B (SEB) is a superantigen known to be a modulator of chronic airway inflammation in mice and humans, yet little is known about the mechanisms that regulate its interaction with the innate immune system. We investigated this mechanism in a murine model of allergic airway inflammation induced by OVA (ovalbumin) in the presence of SEB.

METHODS

Superantigen-induced allergic inflammation was studied in IL-1R knockout (KO) mice exposed to OVA+SEB. Multicolor flow cytometry was used to analyze the inflammatory cell profile in airways and lymph nodes. Production of IL-4, IL-5, IL-10, and IL-13 in lymph nodes was assessed by Luminex technology.

RESULTS

In wild-type mice, endonasal instillation of OVA+SEB induced a pulmonary inflammation, characterized by an increase in the number of eosinophils, T cells, and dendritic cells and in the production of Th2 cytokines and OVA-specific IgE. In IL-1R KO mice exposed to OVA+SEB, attraction of CD4+ cells and production of Th2 cytokines were reduced. However, knocking out IL-1R did not affect any of the features of allergic airway inflammation, such as bronchial eosinophilia, OVA-specific IgE production and goblet cell metaplasia.

CONCLUSION

We provide new insights into the mechanisms of airways allergy development in the presence of bacterial superantigen. The asthma features induced by OVA+SEB, such as bronchial eosinophilia, goblet cell proliferation, production of OVA-specific IgE and increase in inflammatory dendritic cells, are IL-1R independent. Yet, IL-1R signaling is crucial for CD4 cell accumulation and Th2 cytokine production.

Airway exposure to staphylococcal enterotoxin A potentiates allergen-induced bone marrow eosinophilia and trafficking to peripheral blood and airways

Bone marrow (BM) eosinopoiesis is a common feature during allergen exposure in atopic individuals. Airway exposure to staphylococcal superantigens aggravates allergic airway disease and increases the output of BM eosinophils. However, the exact mechanisms regulating eosinophil mobilization and trafficking to the peripheral circulation and airways remain to be elucidated. Therefore, this study aimed to investigate the mechanisms determining the BM eosinopoiesis in allergic mice under exposure to staphylococcal enterotoxin A (SEA). Ovalbumin (OVA)-sensitized male BALB/C mice were intranasally exposed to SEA (1 μg), and at 4, 12, 24, and 48 h later animals were challenged with OVA (10 μg, twice a day). Measurement of IL-5, eotaxin, and granulocyte-macrophage colony-stimulating factor (GM-CSF) levels, flow cytometry for CCR3(+), VLA4(+), and CCR3(+)VLA4(+), as well as adhesion assays to VCAM-1 were performed in BM. Prior airway exposure to SEA time dependently increased the BM eosinophil number in OVA-challenged mice. Eosinophils gradually disappear from peripheral blood, being recruited over time to the airways, where they achieve a maximal infiltration at 24 h. SEA exposure increased the levels of IL-5 and eotaxin (but not GM-CSF) in BM of OVA-challenged mice. Marked increases in CCR3(+) and CCR3(+)VLA4(+) expressions in BM eosinophils of OVA-challenged mice were observed, an effect largely reduced by prior exposure to SEA. Adhesion of BM eosinophils to VCAM-1 was increased in OVA-challenged mice, but prior SEA exposure abrogated this enhanced cell adhesion. Accumulation of BM eosinophils by airway SEA exposure takes place through IL-5- and CCR3-dependent mechanisms, along with downregulation of CCR3/VL4 and impaired cell adhesion to VCAM-1.

Chronic rhinosinusitis and asthma: novel understanding of the role of IgE 'above atopy'

Chronic rhinosinusitis (CRS) affects more than 10% of the European population and is often associated with asthma. Phenotypes of CRS can be differentiated based on mucosal remodelling and inflammatory patterns. Understanding the role of central mediators, such as interleukin-5, in these different phenotypes may lead to the development of specific therapeutic approaches. The impact of staphylococcal superantigens has been shown to further modify the immune response, contributing to persistent severe disease via the activation of T and B cells and the formation of local IgE. It is clear that these mechanisms are involved in the systemic spread of upper airway disease with resulting asthma comorbidity, when IgE antibodies to staphylococcal enterotoxins are present at measurable levels in serum. Recent findings point to superantigens as possible causal agents in the intrinsic form of severe asthma, and an anti-IgE strategy has shown promising therapeutic potential in nonatopic patients with nasal polyps and asthma. These findings should lead to a clinically relevant endotyping of patients with upper and lower airway disease and to a new understanding of the role of IgE 'above atopy'.

Specific IgE against Staphylococcus aureus enterotoxins: an independent risk factor for asthma

BACKGROUND

The role of IgE in patients with severe asthma is not fully understood.

OBJECTIVE

We sought to investigate whether IgE to Staphylococcus aureus enterotoxins might be relevant to disease severity in adult asthmatic patients.

METHODS

Specific IgE antibody concentrations in serum against enterotoxins, grass pollen (GP), and house dust mite allergens and total IgE levels were measured in adult cohorts of 69 control subjects, 152 patients with nonsevere asthma, and 166 patients with severe asthma. Severe asthma was defined as inadequately controlled disease despite high-dose inhaled corticosteroids plus at least 2 other controller therapies, including oral steroids.

RESULTS

Enterotoxin IgE positivity was significantly greater in patients with severe asthma (59.6%) than in healthy control subjects (13%, P< .001). Twenty-one percent of patients with severe asthma with enterotoxin IgE were considered nonatopic. Logistic regression analyses demonstrated significantly increased risks for enterotoxin IgE-positive subjects to have any asthma (OR, 7.25; 95% CI, 2.7-19.1) or severe asthma (OR, 11.09; 95% CI, 4.1-29.6) versus enterotoxin IgE-negative subjects. The presence of GP or house dust mite IgE antibodies was not associated with either significantly increased risk for asthma or severity. Oral steroid use and hospitalizations were significantly increased in patients with enterotoxin IgE and nonatopic asthma. GP IgE was associated with a higher FEV(1) percent predicted value, and enterotoxin IgE was associated with a lower FEV(1) percent predicted value.

CONCLUSIONS

Staphylococcal enterotoxin IgE antibodies, but not IgE against inhalant allergens, are risk factors for asthma severity. We hypothesize that the presence of enterotoxin IgE in serum indicates the involvement of staphylococcal superantigens in the pathophysiology of patients with severe asthma.

B cell immunity in allergic nasal mucosa induces T helper 2 cell differentiation

BACKGROUND

The pathogenesis of allergic diseases is to be further understood. Recent studies indicate that B cells are involved in the immune regulation. The present study aimed to investigate the role of B cells in the initiation of skewed T helper (Th)2 polarization.

METHODS

The surgically removed nasal mucosal specimens from 24 patients with allergic rhinitis (AR) and 22 patients with non-AR (nAR) were collected. B cells isolated from the AR nasal mucosa were characterized. The effect of B cells on inducing naïve CD4+ T cells to differentiate into Th2 cells was evaluated with a cell culture model.

RESULTS

Abundant B cells were detected in the nasal mucosa of patients with AR, which also expressed high levels of T cell immunoglobulin mucin domain (TIM)4 and costimulatory molecules. High levels of Staphylococcal enterotoxin B (SEB) were detected in the AR nasal mucosa. Expression of TIM4 could be induced in naïve B cells in the presence of SEB in culture. TIM4+ B cells could induce naïve CD4+ T cells to differentiate into Th2 cells.

CONCLUSIONS

TIM4+ B cells from AR nasal mucosa can induce skewed Th2 polarization. It may be a potential therapeutic target in the treatment of AR. B cells plays an important role in the initiation of Th2 polarization.

KEY MESSAGES

• High frequency of B cells exists in nasal mucosa of allergic rhinitis • These B cells express high levels of TIM4 • TIM4+ B cells can initiate the skewed Th2 polarization.

Placental growth factor contributes to bronchial neutrophilic inflammation and edema in allergic asthma

Placental growth factor (PlGF) and its receptor vascular endothelial growth factor receptor 1 (VEGFR1) play an important role in pathological conditions related to angiogenesis, vascular leakage, and inflammation. This study investigated their contributions to inflammation and the formation of edema in allergic asthma. The expression of PlGF and VEGFR1 was measured in induced sputum of patients with asthma (n = 11) and healthy subjects (n = 11), and in bronchial biopsies of house dust mite (HDM)-allergic patients stimulated with HDM allergens. The effects of the endonasal administration of human PlGF-2 and PlGF deficiency on inflammation and edema were evaluated in a murine model of allergic asthma. The migration of human neutrophils in response to hPlGF-2 was tested in vitro. The expression of PlGF and VEGFR1 was significantly higher in the sputum of patients with asthma, and in Der p 1-induced PlGF in biopsies from HDM-allergic patients. PlGF was increased in the bronchi of ovalbumin (OVA)-challenged mice compared with control mice (65 ± 17 pg/mg versus 18 ± 1 pg/mg, respectively; P < 0.01), and VEGFR1 was expressed in bronchial epithelium, endothelium (control mice), and inflammatory cells (OVA-challenged mice). The endonasal instillation of hPlGF-2 in wild-type, OVA-challenged mice led to an increase in bronchial neutrophils, lung tissue wet/dry ratio, and IL-17. PlGF-deficient mice showed lower numbers of BAL-infiltrating neutrophils, a reduced lung wet/dry ratio, and lower production of IL-17, macrophage inflammatory protein-2, and granulocyte chemotactic protein-2/LPS-induced chemokine compared with wild-type, OVA-challenged mice. hPlGF-2 induced the migration of human neutrophils in vitro in a VEGFR1-dependent way. PlGF and its receptor VEGFR1 are up-regulated in allergic asthma and play a proinflammatory role by inducing tissue edema, and increasing tissue neutrophilia and the production of IL-17.

Correlation between cytokine levels in nasal fluid and scored clinical parameters in patients with nasal polyposis

The aim of this study was to compare the cytokine levels in nasal fluid in subjects with nasal polyposis (NP) and co-morbid asthma and NP patients without asthma and to correlate these levels with clinical parameters of severity of disease. Forty NP patients (20 asthmatic and 20 nonasthmatic) were enrolled. Nasal secretion samples were collected from nasal cavities of all 40 subjects. The levels of Th1 cytokines IL-2, IL-12 and IFN-γ, Th2 cytokines IL-4, IL-5, IL-6, and IL-10, chemokine IL-8, and proinflammatory cytokines IL-1β, TNF-α and TNF-β were measured using flow cytometric method. Each of the 40 patients was staged clinically according to global nasal symptom score, endoscopic score, and Lund-Mackay computed tomography (CT) score. The concentrations of Th2 cytokines IL-5, IL-6 and IL-10 were significantly higher (P < 0.01, P < 0.01, P < 0.05) in patients with NP and asthma compared with NP patients without asthma. Positive correlations were observed between concentration of IL-2 in nasal secretions and global nasal symptom score, endoscopic score, and Lund-Mackay score only in NP patients without asthma. We also found positive correlation between CT score and the levels of IL-8, IL-4, and IL-1β in nonasthmatic patients. Finally, our results showed a positive correlation between IL-5 levels in nasal fluid and endoscopic score only in asthmatic patients. NP in asthmatic patients have different immunological patterns compared to those without asthma. We also concluded that concentrations of cytokines measured in nasal fluid were not sensitive enough to determine the severity of disease.

Immunopathogenesis of Staphylococcus aureus pulmonary infection

Staphylococcus aureus is a common human pathogen highly evolved as both a component of the commensal flora and as a major cause of invasive infection. Severe respiratory infection due to staphylococci has been increasing due to the prevalence of more virulent USA300 CA-MRSA strains in the general population. The ability of S. aureus to adapt to the milieu of the respiratory tract has facilitated its emergence as a respiratory pathogen. Its metabolic versatility, the ability to scavenge iron, coordinate gene expression, and the horizontal acquisition of useful genetic elements have all contributed to its success as a component of the respiratory flora, in hospitalized patients, as a complication of influenza and in normal hosts. The expression of surface adhesins facilitates its persistence in the airways. In addition, the highly sophisticated interactions of the multiple S. aureus virulence factors, particularly the α-hemolysin and protein A, with diverse immune effectors in the lung such as ADAM10, TNFR1, EGFR, immunoglobulin, and complement all contribute to the pathogenesis of staphylococcal pneumonia.

Exacerbation of cigarette smoke-induced pulmonary inflammation by Staphylococcus aureus enterotoxin B in mice

Background

Cigarette smoke (CS) is a major risk factor for the development of COPD. CS exposure is associated with an increased risk of bacterial colonization and respiratory tract infection, because of suppressed antibacterial activities of the immune system and delayed clearance of microbial agents from the lungs. Colonization with Staphylococcus aureus results in release of virulent enterotoxins, with superantigen activity which causes T cell activation.

Objective

To study the effect of Staphylococcus aureus enterotoxin B (SEB) on CS-induced inflammation, in a mouse model of COPD.

Methods

C57/Bl6 mice were exposed to CS or air for 4 weeks (5 cigarettes/exposure, 4x/day, 5 days/week). Endonasal SEB (10 μg/ml) or saline was concomitantly applied starting from week 3, on alternate days. 24 h after the last CS and SEB exposure, mice were sacrificed and bronchoalveolar lavage (BAL) fluid and lung tissue were collected.

Results

Combined exposure to CS and SEB resulted in a raised number of lymphocytes and neutrophils in BAL, as well as increased numbers of CD8⁺ T lymphocytes and granulocytes in lung tissue, compared to sole CS or SEB exposure. Moreover, concomitant CS/SEB exposure induced both IL-13 mRNA expression in lungs and goblet cell hyperplasia in the airway wall. In addition, combined CS/SEB exposure stimulated the formation of dense, organized aggregates of B- and T- lymphocytes in lungs, as well as significant higher CXCL-13 (protein, mRNA) and CCL19 (mRNA) levels in lungs.

Conclusions

Combined CS and SEB exposure aggravates CS-induced inflammation in mice, suggesting that Staphylococcus aureus could influence the pathogenesis of COPD.

Airway exposure to hypochlorite prior to ovalbumin induces airway hyperreactivity without evidence for allergic sensitization

BACKGROUND

Some epidemiologic studies have indicated that attendance to chlorinated swimming pools is associated with airway hyperreactivity (AHR), allergies and asthma.

AIM

To investigate the effects of sodium hypochlorite (NaClO), the main pool disinfectant, on allergic sensitization and airway inflammation in mice.

METHODS

In a first series of experiments, mice were sensitized to ovalbumin (OVA), followed by OVA aerosols with or without prior nasal instillation of NaClO (3ppm active chlorine). In a second series, naïve mice received 1-7 nasal instillations of OVA, 10min after instillations of NaClO or water. After 1, 3, 5 and 7 exposures airway reactivity to methacholine, cellular inflammation in bronchoalveolar lavage (BAL), serum OVA-specific IgEs and lung Th2 cytokines were measured.

RESULTS

In the first mouse model, airway allergy parameters were not significantly altered upon NaClO administration. However in the second model, NaClO exposure prior to OVA did induce AHR, already after 1 combined application. Combined NaClO+OVA exposure did not lead to an influx of inflammatory cells in BAL fluid or production of anti-OVA IgEs. No AHR developed when OVA was heat-denatured, pre-chlorinated, or replaced by bovine serum albumin or lipopolysaccharide.

CONCLUSION

Nasal instillation of NaClO prior to OVA induces AHR without allergic sensitization. This response is OVA-specific.

Correlation between cytokine levels in nasal fluid and eosinophil counts in nasal polyp tissue in asthmatic and non-asthmatic patients

BACKGROUND/AIMS

Concentrations of mediators in nasal secretions could reflect the inflammatory status of the nasal mucosa and evolution of sinus disease. So, the aim of our study was to evaluate local immune reaction by measuring crucial Th1, Th2 and inflammatory cytokines in nasal fluid samples of patients with nasal polyps (NP), and to correlate them to clinical, radiological findings and to the degree of eosinophil infiltration of polyp tissue. Therefore, in our study we compared the cytokine levels in nasal fluid of asthmatic and non-asthmatic patients with nasal polyposis, the eosinophil counts in NP tissues of these patients, and we correlated cytokine levels with eosinophil counts in NP tissue specimens.

MATERIAL AND METHODS

Thirty patients with nasal polyposis (NP) (15 asthmatic and 15 non-asthmatic) were included in this prospective study. Nasal secretion samples were collected from nasal cavities of all subjects. The levels of 11 cytokines (TNF-α, TNF-β, IL-1β, IL-2, IL-4, IL-5, IL-6, IL-8, IL-10, IL-12, and IFN-γ) were measured using commercial flow cytometric kit. Eosinophils were counted in haematoxylin-and-eosin-stained NP sections.

RESULTS

The concentrations of Th2 cytokines IL-5, IL-6, IL-10, and Th1 cytokine IFN-γ were significantly higher in patients with NP and asthma compared with non-asthmatic subjects. A positive correlation was found between IL-6 and TNF-α levels in nasal fluid and eosinophil counts in polyp tissue in non-asthmatic subjects. In asthmatic NP patients, we found positive correlation between level of IL-6 and eosinophil counts and negative correlation between IFN-γ level and number of eosinophils in NP tissue specimens.

CONCLUSION

Our results showed that these patients with similar clinical findings had significantly different mediator profiles in their nasal secretions, implying clear differences in pathogenesis of their NP.

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.

Superantigens

Superantigens (SAgs) are derived from diverse sources, including bacteria, viruses, and human hepatic tissue. SAgs initially cause lymphocyte activation but then result in clonal deletion and anergy, leading to immune tolerance. They can also act as superallergens by stimulating a broad spectrum of mast cells and basophils in patients with allergic conditions. The newly described staphylococcal SAg-like proteins subvert innate immune function by several mechanisms, which are distinct from SAgs' effects on lymphocytes and other acquired immune processes. There is mounting evidence to suggest that SAgs play a role in the pathophysiology of inflammatory airway disease. The pathophysiologic role of SAg-like proteins awaits clarification.

Global airway disease beyond allergy

Besides the anatomic continuity of the upper and lower airways, inflammation in one part of the airway influences the homeostasis of the other. The mechanisms underlying this interaction have been studied primarily in allergic disease, showing systemic immune activation, induction of inflammation at a distance, and a negative impact of nasal inflammation on bronchial homeostasis. In addition to allergy, other inflammatory conditions of the upper airways are associated with lower airway disease. Rhinosinusitis is frequently associated with asthma and chronic obstructive pulmonary disease. The impairment of purification, humidification, and warming up of the inspired air by the nose in rhinosinusitis may be responsible in part for bronchial pathology. The resolution of sinonasal inflammation via medical and/or surgical treatment is responsible for the beneficial effect of the treatment on bronchial disease. This article provides a comprehensive overview of the current knowledge of upper and lower airway communication beyond allergic disease.

Rhinosinusitis and asthma: a link for asthma severity

The term rhinosinusitis describes an inflammation of the mucosal lining of the nose and sinuses; however, recent evidence points to the need to differentiate patients with chronic rhinosinusitis without nasal polyps from those with nasal polyps. Asthma comorbidity is especially common in nasal polyp disease and may be associated with aspirin-exacerbated respiratory disease. Of interest, asthma comorbidity is uncommon in some parts of the world but common in others. A further analysis of the inflammatory patterns also revealed that nasal polyps do not represent one single entity; interleukin (IL)-5-positive nasal polyps can be differentiated from IL-5-negative forms by different inflammatory patterns (predominance of eosinophils vs neutrophils). Staphylococcus aureus superantigens frequently colonize IL-5-positive nasal polyps and may amplify the eosinophilic inflammation, induce a polyclonal local IgE formation, and increase the risk of asthma comorbidity. Recent findings in severe asthma patients confirm the role of superantigens in lower airway disease.

Staphylococcus aureus enterotoxin B augments granulocyte migration and survival via airway epithelial cell activation

BACKGROUND

Staphylococcus aureus enterotoxin B (SEB) has recently been postulated to be involved in the pathology of granulocyte-dominated disease. Studying the immunologic interaction between SEB and airway epithelial cells in immortalized cell lines or long-term epithelial cell cultures has obvious disadvantages.

METHODS

We used a novel technique of freshly isolated and purified human nasal epithelial cells (HNEC) from healthy, nonallergic individuals, which were incubated for 24 h without/with SEB at different concentrations. Chemokine production was evaluated in the supernatant using Cytometric Bead Array. The chemotactic activity of the supernatant was studied in vitro using a Boyden chamber. Survival was evaluated with flow cytometry, using propidium iodide to identify dead cells.

RESULTS

Staphylococcus aureus enterotoxin B showed a dose-dependent induction of interferon-inducible protein-10, monokine induced by interferon-gamma, regulated upon activation normal T cell expressed and secreted, monocyte chemoattractant protein 1 (MCP-1) and granulocyte colony stimulating factor production by epithelial cells in vitro. The supernatant of epithelial cells had chemotactic activity for granulocytes in vitro, which was enhanced in the supernatant of SEB-stimulated epithelial cells. Reduced number of propidium iodide positive granulocytes was found in the conditions where supernatant of SEB-stimulated epithelial cells was applied.

CONCLUSION

Staphylococcus aureus enterotoxin B exerts a direct pro-inflammatory effect on HNEC, with induction of chemokine and growth factor release, resulting in the migration and prolonged survival of granulocytes in vitro.

The systemic and pulmonary immune response to staphylococcal enterotoxins

In response to environmental cues the human pathogen Staphylococcus aureus synthesizes and releases proteinaceous enterotoxins. These enterotoxins are natural etiologic entities of severe food poisoning, toxic shock syndrome, and acute diseases. Staphylococcal enterotoxins are currently listed as Category B Bioterrorism Agents by the Center for Disease Control and Prevention. They are associated with respiratory illnesses, and may contribute to exacerbation of pulmonary disease. This likely stems from the ability of Staphylococcal enterotoxins to elicit powerful episodes of T cell stimulation resulting in release of pro-inflammatory cytokines. Here, we discuss the role of the immune system and potential mechanisms of disease initiation and progression.

Rhinosinusitis and the lower airways

The interaction between upper and lower airway disease has been recognized for centuries, with recent studies showing a direct link between upper and airway inflammation in allergic patients. The mechanisms underlying the interaction between nasal and bronchial inflammation have primarily been studied in allergic disease, showing systemic immune activation after allergen inhalation, induction of inflammation at a distance, and a negative impact of nasal inflammation on bronchial homeostasis. Therefore, allergic rhinitis and asthma are considered part of the global airway allergy syndrome. Besides allergy, other inflammatory conditions such as the common cold, acute rhinosinusitis, and chronic rhinosinusitis are associated with lower airway disease. Chronic sinus disease with or without nasal polyps are frequently found in patients with asthma and chronic obstructive pulmonary disease with improvement of bronchial symptoms and respiratory function by adequate medical and surgical therapy for rhinosinusitis. The resolution of sinonasal inflammation and hence sinonasal functions by medical or surgical treatment is considered responsible for the beneficial effect of treatment on bronchial disease. This article aims at providing a comprehensive overview of the current knowledge on the interaction between common cold, acute and chronic rhinosinusitis, and lower airway biology.

Staphylococcus aureus enterotoxin B facilitates allergic sensitization in experimental asthma

BACKGROUND

Staphylococcus aureus Enterotoxin B (SEB) has immunomodulatory effects in allergic airway disease. The potential contribution of SEB to the sensitization process to allergens remains obscure.

OBJECTIVE

In order to study the effects of staphylococcal-derived toxins on the sensitization to ovalbumin (OVA) and induction of allergic airway inflammation, we have combined the nasal application of OVA with different toxins.

METHODS

Nasal applications of OVA and saline, SEA, SEB, toxic shock syndrome toxin (TSST)-1, protein A or lipopolysaccharide (LPS) were performed on alternate days from day 0 till 12. On day 14, mice were killed for the evaluation of OVA-specific IgE, cytokine production by mediastinal lymph node (MLN) cells and bronchial hyperreactivity (BHR) to inhaled metacholine. The effect of SEB on dendritic cell (DC) migration and maturation, and on T cell proliferation was evaluated.

RESULTS

Concomitant endonasal application of OVA and SEB resulted in OVA-specific IgE production, whereas this was not found with SEA, TSST-1, protein A, LPS or OVA alone. Increased DC maturation and migration to the draining lymph nodes were observed in OVA/SEB mice, as well as an increased T cell proliferation. Bronchial inflammation with an influx of eosinophils and lymphocytes was demonstrated in OVA/SEB mice, together with hyperresponsiveness and the production of IL-4, IL-5, IL-10 and IL-13 by MLN stimulated with OVA.

CONCLUSIONS

Our data demonstrate that SEB facilitates sensitization to OVA and consecutive bronchial inflammation with features of allergic asthma. This is likely due to augmentation of DC migration and maturation, as well as the allergen-specific T cell proliferation upon concomitant OVA and SEB application.

Cytokine Profiles in Nasal Fluid in Patients with Nasal Polyps: A Flow Cytometric Study

Biological markers in nasal fluid provide valuable information on nasal pathophysiology. The aims of this study were to compare the cytokine profiles of nasal fluid in subjects with nasal polyps (NP) and co-morbid asthma and NP patients without asthma and to determine the role of these cytokines in the development of NP. Thirty patients with NP (15 asthmatic and 15 non asthmatic) were included in this prospective study. Nasal secretion samples were collected from nasal cavities of all 30 subjects. The levels of eleven cytokines (TNF-α, TNF-β, IL-1β, IL-2, IL-4, IL-5, IL-6, IL-8, IL-10, IL-12, and IFN-γ) were measured using flow cytometry. The concentrations of Th2 cytokines IL-5, IL-6 and IL-10 were significantly higher in patients with NP and asthma compared with subjects with NP without asthma. We also found significantly higher levels of IFN-α, IL-4, IL-6 and IL-10 in allergic patients with NP and asthma compared with those without asthma. In nonallergic patients with NP and asthma, the concentrations of TNF-α, IL-5 and IL-6 were significantly higher than in nonallergic patients with NP without asthma. Our results show that the presence of Th2 cytokines, especially IL-5 and IL-6 in patients with NP and asthma is a more prominent feature than in those without asthma that relates to the increased eosinophilic inflammation. We have also found a significant influence of allergy on the cytokine profiles both in asthmatic and nonasthmatic patients.

Pre-exposure to Staphylococcal enterotoxin A exacerbates the pulmonary allergic eosinophil recruitment in rats

Gram-positive Staphylococcus aureus releases classical enterotoxins which aggravates allergic airway diseases. However, little is known about the mechanisms underlying the cell influx exacerbation in asthmatic individuals under exposure to Staphylococcal enterotoxins. We therefore aimed to investigate the effects of airways exposure to Staphylococcal enterotoxin A (SEA) to pulmonary leukocyte recruitment in rats sensitized and challenged with ovalbumin (OVA). Rats were exposed to SEA at 4h prior to OVA challenge or at 4h post-OVA challenge. Bronchoalveolar lavage (BAL) fluid, bone marrow and lung tissue were obtained at 24h after OVA challenge. Pre-exposure to SEA markedly enhanced the eosinophil counts in both BAL fluid and pulmonary tissue in OVA-challenged rats, whereas neutrophil and mononuclear cell counts remained unchanged. In bone marrow, pre-exposure to SEA alone significantly increased the number of eosinophils, and that was further increased in OVA-challenged rats. Exposure to SEA post-OVA challenge did not affect the number of eosinophils, neutrophils and mononuclear cells in BAL fluid. Pre-exposure to the endotoxin lipopolyssacharide (LPS) in OVA-challenged animals rather enhanced the neutrophil number in BAL fluid. In rats pre-exposed to SEA and OVA-challenged, a marked elevation in the levels of TNF-alpha and eotaxin (but not of IL-10) in BAL fluid was observed. The eotaxin levels increased by about of 3-fold in alveolar macrophages treated with SEA in vitro. In conclusion, airways pre-exposure to SEA causes a selective increase in eosinophil number in BAL fluid and bone marrow of OVA-challenged rats by mechanisms involving enhancement of TNF-alpha and eotaxin synthesis.