Role of staphylococcal superantigens in airway disease

Analysis of olfactory function in patients with chronic rhinosinusitis and Staphylococcus aureus enterotoxin positivity

To investigate disparities in sensitisation to Staphylococcus aureus enterotoxin A/B (SEA/SEB) and olfactory function in patients with chronic rhinosinusitis (CRS) with nasal polyps (CRSwNP), those with CRS without nasal polyps (CRSsNP), and healthy controls who underwent septoplasty only. We retrospectively reviewed the medical records of 388 subjects aged ≥ 8 years, collected between January 2021 and June 2023. We analysed patient demographics, medical history, serum IgE levels against staphylococcal enterotoxins (SEs), and serum total IgE levels against inhalant allergens. We performed olfactory and taste function tests in the participants to evaluate the relationship between olfactory function and SEs. Of 388 patients enrolled, 145 were healthy controls, 111 had CRSsNP, and 133 had CRSwNP. The prevalence of SEA/SEB positivity was significantly higher among the patients with CRSwNP than among those in the CRSsNP and healthy controls. The olfactory test results showed significant differences among the groups; anosmia was observed in 9.7% of healthy controls, 22.7% of patients with CRSsNP, and 45.1% of patients with CRSwNP. Olfactory threshold deterioration was evident in patients with CRS. Distinction and identification were more impaired in patients with CRSwNP than in those of the other groups. Finally, the olfactory function scores decreased as the serum levels of SEs increased. Sinusitis patients seem to suffer from perceiving odours, and patients with CRSwNP have difficulty distinguishing odours. Olfactory function test scores decreased in patients with a history of asthma, and as serum levels of staphylococcus enterotoxin and blood eosinophil percentage increase. Furthermore, our result suggests a potential role for SE sensitisation and eosinophil percentage in deteriorating olfaction, especially in patients with CRSwNP.

Association between interleukin-6-174G/C gene polymorphism and asthma severity: exploring the role of total serum IgE, blood eosinophils, and FeNO as markers of type 2 inflammation

BACKGROUND

While a connection has been established between serum interleukin-6 (IL-6) levels and the IL-6 gene (- 174G/C) polymorphism in allergic diseases such as asthma, its specific association with severe asthma remains unexplored. This study examined the relationship between the IL-6 (- 174G/C) gene polymorphism and mild and severe asthma, focusing on its influence on type 2 inflammation.

METHODS

Our study comprised 98 patients with mild asthma and 116 with severe asthma. Additionally, we recruited 121 healthy participants to serve as controls for comparative analyses. The IL-6 gene (- 174G/C) polymorphism was assessed utilizing the polymerase chain reaction-restriction fragment length polymorphism (PCR-RFLP) method.

RESULTS

In our study, the risk of mild asthma exhibited a significant fourfold increase in individuals with the GG genotype pattern compared to healthy controls, yielding an odds ratio (OR) of 4.4 (p < 0.001). Conversely, we found no significant correlation between the IL-6 - 174G/C gene polymorphism and severe asthma when compared to the healthy control group. However, a noteworthy pattern emerged when we compared subgroups of mild and severe asthma. The risk of severe asthma increased fivefold in individuals with the GC polymorphism pattern, with an OR of 4.99 (p < 0.001), while the likelihood of mild asthma showed a similar fourfold increase with the GG polymorphism pattern, OR = 4.4 (p < 0.001). Consequently, we observed a significantly higher frequency of the C allele in patients with severe asthma, whereas the G allele was more prevalent in individuals with mild asthma (p = 0.05). Additionally, the correlation between markers of type 2 inflammation and the dominant model of the IL-6 gene -174G/C polymorphism (CC + CG vs GG) revealed a significant increase in total serum immunoglobulin E (IgE), Blood Eosinophil Counts (BEC), and Fractional Exhaled Nitric Oxide (FeNO) levels in asthmatic patients with the CC + CG gene pattern compared to those with GG, with p-values of 0.04, 0.03, and 0.04, respectively. Furthermore, after adjusting for other risk factors, the likelihood of developing severe asthma increased from fourfold to eightfold, with an OR of 8.12 (p = 0.01) with (CC + CG) gene pattern. Other predictors for severe asthma included older age and childhood-onset disease (OR = 1.13 and 19.19, p < 0.001). Allergic rhinitis (AR) and nasal polyps (NP) also demonstrated a substantial association with an increased risk of severe asthma, with odds ratios of 5 and 32.29 (p = 0.01 and < 0.001), respectively. Additionally, elevated Body Mass Index (BMI), BEC, and FeNO were linked to severe asthma, with ORs of 1.11, 1.00, and 1.04, respectively (p = 0.04, 0.05, and 0.001).

CONCLUSION

This study illuminated the intricate relationship between the IL-6 gene polymorphism, type 2 inflammation markers, and diverse risk factors in shaping asthma severity. As a significant association between the GG polymorphism of the IL-6 gene (- 174G/C) and mild asthma was found, while possessing at least one C allele, whether in a homozygous (CC) or heterozygous (CG) combination, independently predicts the likelihood of severe asthma.

2B4: A potential target in Staphylococcus aureus associated allergic inflammation

Staphylococcus aureus (SA) and its exotoxins activate eosinophils (Eos) and mast cells (MCs) via CD48, a GPI-anchored receptor belonging to the signaling lymphocytes activation molecules (SLAM) family. 2B4 (CD244), an immuno-regulatory transmembrane receptor also belonging to the SLAM family, is the high-affinity ligand for CD48. 2B4 is expressed on several leukocytes including NK cells, T cells, basophils, monocytes, dendritic cells (DCs), and Eos. In the Eos and MCs crosstalk carried out by physical and soluble interactions (named the 'allergic effector unit', AEU), 2B4-CD48 binding plays a central role. As CD48 and 2B4 share some structural characteristics and SA colonization accompanies most of the allergic diseases, we hypothesized that SA exotoxins (e.g. Staphylococcus enterotoxin B, SEB) can also bind and activate 2B4 and thereby possibly further aggravate inflammation. To check our hypothesis, we used in vitro, in silico, and in vivo methods. By enzyme-linked immunosorbent assay (ELISA), flow cytometry (FC), fluorescence microscopy, and microscale thermophoresis, we have shown that SEB can bind specifically to 2B4. By Eos short- and long-term activation assays, we confirmed the functionality of the SEB-2B4 interaction. Using computational modeling, we identified possible SEB-binding sites on human and mouse 2B4. Finally, in vivo, in an SEB-induced peritonitis model, 2B4-KO mice showed a significant reduction of inflammatory features compared with WT mice. Altogether, the results of this study confirm that 2B4 is an important receptor in SEB-mediated inflammation, and therefore a role is suggested for 2B4 in SA associated inflammatory conditions.

Association between poly-sensitisation and sensitisation to staphylococcal enterotoxin A and B affecting allergic severity in children

PURPOSE

Accumulating evidence suggests that Staphylococcus aureus plays a significant role as a disease modifier in upper and lower airway diseases. We aimed to assess the association between staphylococcal enterotoxins (SEs) with allergic diseases and the degree of allergen sensitisation in children, which remains unclear.

METHODS

We retrospectively reviewed the medical records of 455 patients aged 3-18 years between March 2018 and March 2022. Clinical history and demographic data were obtained. The baseline study included paranasal sinus X-ray scan, multiple allergen simultaneous test, and ImmunoCAP® for measuring serum total and specific immunoglobulin E (IgE) levels to allergens and staphylococcal enterotoxin A and B (SEA and SEB).

RESULTS

The mean age was 9.77 ± 4.3 years. 133 patients (29.2%) were sensitised to one inhalant allergen, and 188 patients (41.3%) showed polysensitisation. Patients sensitised to SEs showed higher total and specific IgE levels and total eosinophil counts compared to non-SE-sensitised patients. Sensitisation to SEs is closely associated with polysensitisation to inhalant allergens and allergic multimorbidity. When the SE-IgE value was 0.35 or higher, the odds ratio for allergen polysensitisation was significantly higher than when the SE-IgE value was lower than 0.35.

CONCLUSIONS

Association between polysensitisation and sensitisation to SEs in children shows the higher the specific IgE levels for SEs, the higher the likelihood of polysensitisation. Considering the relationship between polysensitisation, high IgE levels, and the severity of allergic morbidity, sensitisation to SEs is thought to be related to allergy severity.

Pathogenesis of Nasal Polyposis: Current Trends

Chronic Rhinosinusitis (CRS) is characterized by edema of the sub-epithelial layers, but, only specific types of CRS are developing polyps. Nasal polyposis may develop under different pathogenetic mechanisms rendering the typical macroscopic classification of CRS, with or without nasal polyps, rather deficient. Currently, we approach nasal polyposis, in terms of diagnosis and treatment, according to its endotype, which means that we focus on the specific cells and cytokines that are participating in its pathogenesis. It appears that the molecular procedures that contribute to polyp formation, initiating with a Th-2 response of the adaptive immune system, are local phenomena occurring in the sub-epithelial layers of the mucosa. Several hypotheses are trying to approach the etiology that drives the immune response towards Th-2 type. Extrinsic factors, like fungi, Staphylococcus superantigens, biofilms, and altered microbiome can contribute to a modified and intense local reaction of the immune system. Some hypotheses based on intrinsic factors like the elimination of Treg lymphocytes, low local vitamin-D levels, high levels of leukotrienes, epithelial to mesenchymal transition (EMT) induced by hypoxia, and altered levels of NO, add pieces to the puzzle of the pathogenesis of nasal polyposis. Currently, the most complete theory is that of epithelial immune barrier dysfunction. Intrinsic and extrinsic conditions can damage the epithelial barrier rendering sub-epithelial layers more vulnerable to invasion by pathogens that trigger a Th-2 response of the adaptive immune system. Th2 cytokines, subsequently, induce the accumulation of eosinophils and IgE together with the remodeling of the stroma in the sub-epithelial layers leading, eventually, to the formation of nasal polyps.

Divergent dynamics of inflammatory mediators and multiplex PCRs during airway infection in cystic fibrosis patients and healthy controls: Serial upper airway sampling by nasal lavage

Background

In cystic fibrosis (CF), acute respiratory exacerbations critically enhance pulmonary destruction. Since these mainly occur outside regular appointments, they remain unexplored. We previously elaborated a protocol for home-based upper airway (UAW) sampling obtaining nasal-lavage fluid (NLF), which, in contrast to sputum, does not require immediate processing. The aim of this study was to compare UAW inflammation and pathogen colonization during stable phases and exacerbations in CF patients and healthy controls.

Methods

Initially, we obtained NLF by rinsing 10 ml of isotonic saline/nostril during stable phases. During exacerbations, subjects regularly collected NLF at home. CF patients directly submitted one aliquot for microbiological cultures. The remaining samples were immediately frozen until transfer on ice to our clinic, where PCR analyses were performed and interleukin (IL)-1β/IL-6/IL-8, neutrophil elastase (NE), matrix metalloproteinase (MMP)-9, and tissue inhibitor of metalloproteinase (TIMP)-1 were assessed.

Results

Altogether, 49 CF patients and 38 healthy controls (HCs) completed the study, and 214 NLF samples were analyzed. Of the 49 CF patients, 20 were at least intermittently colonized with P. aeruginosa and received azithromycin and/or inhaled antibiotics as standard therapy. At baseline, IL-6 and IL-8 tended to be elevated in CF compared to controls. During infection, inflammatory mediators increased in both cohorts, reaching significance only for IL-6 in controls (p=0.047). Inflammatory responses tended to be higher in controls [1.6-fold (NE) to 4.4-fold (MMP-9)], while in CF, mediators increased only moderately [1.2-1.5-fold (IL-6/IL-8/NE/TIMP-1/MMP-9)]. Patients receiving inhalative antibiotics or azithromycin (n=20 and n=15, respectively) revealed lower levels of IL-1β/IL-6/IL-8 and NE during exacerbation compared to CF patients not receiving those antibiotics. In addition, CF patients receiving azithromycin showed MMP-9 levels significantly lower than CF patients not receiving azithromycin at stable phase and exacerbation. Altogether, rhinoviruses were the most frequently detected virus, detected at least once in n=24 (49.0%) of the 49 included pwCF and in n=26 (68.4%) of the 38 healthy controls over the 13-month duration of the study. Remarkably, during exacerbation, rhinovirus detection rates were significantly higher in the HC group compared to those in CF patients (65.8% vs. 22.4%; p<0.0001).

Conclusion

Non-invasive and partially home-based UAW sampling opens new windows for the assessment of inflammation and pathogen colonization in the unified airway system.

Immunopathologic Role of Eosinophils in Eosinophilic Chronic Rhinosinusitis

Chronic rhinosinusitis (CRS) is a diverse chronic inflammatory disease of the sinonasal mucosa. CRS manifests itself in a variety of clinical and immunologic patterns. The histological hallmark of eosinophilic CRS (ECRS) is eosinophil infiltration. ECRS is associated with severe disease severity, increased comorbidity, and a higher recurrence rate, as well as thick mucus production. Eosinophils play an important role in these ECRS clinical characteristics. Eosinophils are multipotential effector cells that contribute to host defense against nonphagocytable pathogens, as well as allergic and nonallergic inflammatory diseases. Eosinophils interact with Staphylococcus aureus, Staphylococcal enterotoxin B, and fungi, all of which were found in the tissue of CRS patients. These interactions activate Th2 immune responses in the sinonasal mucosa and exacerbate local inflammation. Activated eosinophils were discovered not only in the tissue but also in the sinonasal cavity secretion. Eosinophil extracellular traps (EETs) are extracellular microbes trapping and killing structures found in the secretions of CRS patients with intact granule protein and filamentous chromatic structures. At the same time, EET has a negative effect by causing an epithelial barrier defect. Eosinophils also influence the local tissue microenvironment by exchanging signals with other immune cells and structural cells. As a result, eosinophils are multifaceted leukocytes that contribute to various physiologic and pathologic processes of the upper respiratory mucosal immune system. The goal of this review is to summarize recent research on the immunopathologic properties and immunologic role of eosinophils in CRS.

Microcalorimetric Investigations of Reversible Staphylococcal Enterotoxin Unfolding

Staphylococcal food poisoning (SFP) is a common food-borne illness often associated with contamination during food handling. The genes for Staphylococcal enterotoxin (SE) isoforms SEA and SEB are frequently detected in human nasal Staphylococcus aureus isolates and these toxins are commonly associated with SFP. Past studies described the resistance of preformed SE proteins to heat inactivation and their reactivation upon cooling in foods. Full thermodynamic analyses for these processes have not been reported, however. The thermal stabilities of SEA, SEB, and SEH and reversibility of unfolding in simple buffers were investigated at pH 4.5 and pH 6.8 using differential scanning calorimetry (DSC). SEA and SEB unfolding was irreversible at pH 6.8 and at least partially reversible at pH 4.5 while SEH unfolding was irreversible at pH 4.5 and reversible at pH 6.8. Additional studies showed maximum refolding for SEB at pH 3.5–4.0 and diminished refolding at pH 4.5 with increasing ionic strength. SE-stimulated secretion of interferon-gamma by human peripheral blood mononuclear cells was used to assess residual SE biological activity following heat treatments using conditions matching those used for DSC studies. The biological activities of SEB and SEH exhibited greater resistance to heat inactivation than that of SEA. The residual activities of heat-treated SEB and SEH were measurable but diminished further in the presence of reconstituted nonfat dry milk adjusted to pH 4.5 or pH 6.8. To different extents, the pH and ionic strengths typical for foods influenced the thermal stabilities of SEA, SEB, and SEH and their potentials to renature spontaneously after heat treatments.

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.

The role of Staphylococcus aureus enterotoxin B in chronic rhinosinusitis with nasal polyposis

CRS with nasal polyps (CRSwNP) is a multifactorial disease, and various etiological factors like bacterial superantigens are known to develop this disease. Recent studies reported that Staphylococcus aureus nasal colonization was detected in 67% of the patients with CRSwNP. Moreover, it was reported that specific IgE against S. aureus enterotoxins are discovered in almost half of the nasal tissue homogenates from nasal polyps. Thus, investigations have highlighted the role of staphylococcal enterotoxins, especially enterotoxin B (SEB), in pathogenesis of CRSwNP. The destruction of mucosal integrity was reported as a main SEB-related pathogenic mechanisms in CRSwNP. SEB activates Toll Like Receptor 2 and triggers the production of pro-inflammatory cytokines; furthermore, it induces reactive oxygen species and endoplasmic reticulum stress-induced inflammation that may cause epithelial cell integrity disruption and enhance their permeability. SEB-induced Type 2/Th2 pathway results in degranulation of eosinophils, cationic proteins production, and localized eosinophilic inflammation. Furthermore, SEB may be involved in the expression of RORC and HIF-1α in Tregs and by maintaining the inflammation in sinonasal mucosa that could have a main role in the pathogenesis of nasal polyposis. Different in vitro findings were confirmed in animal studies; however, in vivo analysis of SEB-induced nasal polyps and CRS remains unfulfilled due to the lack of appropriate animal models. Finally, after elucidating different aspects of SEB pathogenesis in CRSwNP, therapeutic agents have been tested in recent studies with some encouraging results. The purpose of this article is to summarize the most important findings regarding SEB-induced CRS and nasal polyposis.

DNA methylation profile in patients with indolent systemic mastocytosis

BACKGROUND

Mastocytosis is a clinically heterogeneous, usually acquired disease of the mast cells with a survival time that depends on the onset of the disease and ranges from skin-limited to systemic disease, including indolent and more aggressive variants. The crucial element in pathogenesis is the presence of oncogenic KIT somatic mutation D816V. Further epigenetic alterations are responsible for regulating the expression of genes. It is essential to identify indicators of disease progression, and the specific clinical picture to establish an appropriate therapeutic strategy.

OBJECTIVE

The aim of this study was to analyze the relation of mastocytosis symptoms and epigenetic changes, and to identify epigenetic predictors of the disease.

METHODS

Global DNA methylation profile analysis was performed in peripheral blood collected from 73 patients with indolent systemic mastocytosis (ISM) and 43 healthy adult volunteers. Levels of 5-methylcytosine (5-mC) and 5-hydroxymethylcytosine (5-hmC) were determined using an ELISA-based method, while the methylation of the Alu and LINE-1 repeats were assayed with the quantitative methylation-specific PCR technique. A questionnaire interview was conducted among the study participants to collect data on possible epigenetic modifiers. Additionally, the methylation profile was compared between three human mast cell lines: ROSA KIT D816V, ROSA KIT WT, and HMC-1.1 KIT V560G, in order to assess the association between KIT mutations and methylation profile.

RESULTS

A significantly lower level of DNA hydroxymethylation (5-hmC) in the blood was found in patients with ISM as compared to the controls (0.022% vs. 0.042%, p = 0.0001). Differences in the markers of global DNA methylation (5-mC, Alu, LINE-1) were not statistically significant, although they did indicate generally higher DNA methylation in patients with mastocytosis. The 5-hmC level was significantly associated with allergy (p = 0.011) in patients with ISM, showing a higher level of 5-hmC in patients with allergy as compared to patients without allergy. The in vitro study revealed significant differences between the studied cell lines at the level of 5-mC, Alu, and LINE-1.

CONCLUSIONS

This study confirms that epigenetic changes are involved in mastocytosis, and suggests that allergy may be an important epigenetic modifier of the disease. A possible association between KIT mutations and methylation status observed in human mast cell lines requires further investigation in human studies.

CLINICAL IMPLICATIONS

Epigenetic alterations are involved in mastocytosis pathology. The possible role of allergy as an important epigenetic modifier suggests the more impaired function of mast cells in ISM patients without allergy.

CAPSULE SUMMARY

Decreased DNA demethylation in the blood DNA of patients with ISM confirms that epigenetic alterations are involved in mastocytosis pathology. We observed a possible role of allergy as an important epigenetic modifier. There is a possible association between KIT mutations and the methylation status observed in human mast cell lines.

The Role of Atopy in COPD and Asthma

Common to several allergic diseases is the generation of immunoglobulin E (IgE) by plasma cells, when exposed to an innocuous antigen. Asthma and chronic obstructive pulmonary disease (COPD) are two prevalent chronic airway inflammatory diseases. Asthma is mediated in some patients through eosinophilic inflammatory mechanisms that include allergic sensitization and Th2-mediated immune airway response. COPD, on the other hand is mainly considered a Th1-mediated inflammatory process with neutrophilic predominance or a non-Th2 inflammation, occasionally associated with the presence of airway bacteria or viruses. IgE production appears to play an important role in the development of both COPD and asthma, as it has been associated to respiratory symptoms, lung function, bacterial and viral infections, airway remodeling and bronchial hyperreactivity in both diseases. The aim of this review is to summarize all current data concerning the role of specific and total IgE in COPD and asthma and to highlight similarities and differences in view of possible therapeutic interventions.

Can the sensitisation to staphylococcal enterotoxin predict the severity of chronic rhinosinusitis?

BACKGROUND

Evidence is accumulating that Staphylococcus aureus plays an important role as a disease modifier in upper and lower airway disease. We aimed to assess the association of staphylococcal enterotoxins (SEs) with allergic multimorbidity as well as the severity of chronic rhinosinusitis.

METHODS

We retrospectively reviewed the medical records of 97 subjects aged 6 years or older between March 2018 and June 2019 and analysed symptom scores, computed tomography scores, serum IgE levels to SEs, serum total and specific IgE levels to inhalant allergens. To evaluate eosinophilic chronic rhinosinusitis (ECRS), we used refractory ECRS score from the Japanese epidemiological survey.

RESULTS

Of the 97 patients enrolled, 29 (29.9%) were non-sensitised, 33 (34.0%) were mono-sensitised, and 35 (36.1%) were poly-sensitised. Sensitisation to SEs was closely associated with poly-sensitisation to inhalant allergens. SE-sensitised participants had higher median values for total and specific IgE levels to inhalant allergens than did non-SE-sensitised participants. SE sensitisation was associated with allergic multimorbidity and severe allergic diseases, such as ECRS.

CONCLUSIONS

This preliminary study suggested that sensitisation to SEs may play a role in the initiation of type-2 inflammatory responses, such as allergic rhinitis, ECRS, and allergic multimorbidity. Furthermore, sensitisation to SEs correlated with the severity of ECRS.

Staphylococcus aureus and its Effects on the Prognosis of Bronchiectasis

Bronchiectasis, which is an abnormal and irreversible dilation of one or several bronchial segments, causes significant morbidity and impaired quality of life to patients, mainly as the result of recurrent and chronic respiratory infections. Staphylococcus aureus is a microorganism known for its high infectious potential related to the production of molecules with great pathogenic power, such as enzymes, toxins, adhesins, and biofilm, which determine the degree of severity of systemic symptoms and can induce exacerbated immune response. This review highlighted the clinical significance of S. aureus colonization/infection in bronchiectasis patients, since little is known about it, despite its increasing frequency of isolation and potential serious morbidity.

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.

Molecular docking analysis of Enterotoxin I from Staphylococcus aureus with Nafcillin analogues

Staphylococcal enterotoxins (SEs) are liked with food poisoning and other related infections. Nafcillin is an antibiotic used to treat S. aureus. Therefore, it is of interest to study the molecular interactions of 25 nafcillin analogues with enterotoxin I using molecular docking analysis. The analysis shows optimal interaction features of Nafcillin analogues with Enterotoxin I from Staphylococcus aureus for further consideration.

Staphylococcus aureus enterotoxin B disrupts nasal epithelial barrier integrity

BACKGROUND

Staphylococcus aureus colonization and release of enterotoxin B (SEB) has been associated with severe chronic rhinosinusitis with nasal polyps (CRSwNP). The pathogenic mechanism of SEB on epithelial barriers, however, is largely unexplored.

OBJECTIVE

We investigated the effect of SEB on nasal epithelial barrier function.

METHODS

SEB was apically administered to air-liquid interface (ALI) cultures of primary polyp and nasal epithelial cells of CRSwNP patients and healthy controls, respectively. Epithelial cell integrity and tight junction expression were evaluated. The involvement of Toll-like receptor 2 (TLR2) activation was studied in vitro with TLR2 monoclonal antibodies and in vivo in tlr2^-/- knockout mice.

RESULTS

SEB applied to ALI cultures of polyp epithelial cells decreased epithelial cell integrity by diminishing occludin and zonula occludens (ZO)-1 protein expression. Antagonizing TLR2 prevented SEB-induced barrier disruption. SEB applied in the nose of control mice increased mucosal permeability and decreased mRNA expression of occludin and ZO-1, whereas mucosal integrity and tight junction expression remained unaltered in tlr2^-/- mice. Furthermore, in vitro SEB stimulation resulted in epithelial production of IL-6 and IL-8, which was prevented by TLR2 antagonization.

CONCLUSION & CLINICAL RELEVANCE

SEB damages nasal polyp epithelial cell integrity by triggering TLR2 in CRSwNP. Our results suggest that SEB might represent a driving factor of disease exacerbation, rather than a causal factor for epithelial defects in CRSwNP. Interfering with TLR2 triggering might provide a way to avoid the pathophysiological consequences of S. aureus on inflammation in CRSwNP.

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.

Biologics for the Treatment of Allergic Rhinitis, Chronic Rhinosinusitis, and Nasal Polyposis

Allergic rhinitis (AR), most presentations of nasal polyposis (NP), and many presentations of chronic rhinosinusitis are type 2^high disorders characterized by expression of interleukin (IL)-4, IL-5, and IL-13. Neutralization of IgE with anti-IgE (omalizumab) has proven efficacy in AR. Similarly, in addition to anti-IgE, blockade of IL-5/IL-5 (mepolizumab, reslizumab, benralizumab) and dual blockade of IL-4 and IL-13 with anti-IL-4R (dupilumab) have demonstrated efficacy in NP. However, these agents are expensive and future studies are essential to evaluate cost effectiveness in comparison with current medical and surgical therapies. This article reviews biologics as potential interventions in AR, chronic rhinosinusitis, and NP.

Allergy-A New Role for T Cell Superantigens of Staphylococcus aureus?

Staphylococcus aureus superantigens (SAgs) are among the most potent T cell mitogens known. They stimulate large fractions of T cells by cross-linking their T cell receptor with major histocompatibility complex class-II molecules on antigen presenting cells, resulting in T cell proliferation and massive cytokine release. To date, 26 different SAgs have been described in the species S. aureus; they comprise the toxic shock syndrome toxin (TSST-1), as well as 25 staphylococcal enterotoxins (SEs) or enterotoxin-like proteins (SEls). SAgs can cause staphylococcal food poisoning and toxic shock syndrome and contribute to the clinical symptoms of staphylococcal infection. In addition, there is growing evidence that SAgs are involved in allergic diseases. This review provides an overview on recent epidemiological data on the involvement of S. aureus SAgs and anti-SAg-IgE in allergy, demonstrating that being sensitized to SEs—in contrast to inhalant allergens—is associated with a severe disease course in patients with chronic airway inflammation. The mechanisms by which SAgs trigger or amplify allergic immune responses, however, are not yet fully understood. Here, we discuss known and hypothetical pathways by which SAgs can drive an atopic disease.

Use of endotypes, phenotypes, and inflammatory markers to guide treatment decisions in chronic rhinosinusitis

OBJECTIVE

With the advent of new treatment options for Chronic Rhinosinusitis (CRS) comes the ability for physicians to provide more individualized patient care. Physicians are now tasked with identifying who may be the best candidate for a particular therapy. In this review, existing biomarkers and potentially new methods that could guide treatment choices in CRS patients will be discussed.

DATA SOURCES

Published literature obtained through PubMed searches.

STUDY SELECTION

Studies relevant to inflammatory endotypes, phenotypes, and biomarkers in CRS were included.

RESULTS

Currently, there are no clinically validated tools that determine the best therapeutic modality for CRS patients with or without nasal polyps (CRSwNP or CRSsNP). Patients with CRS can be classified into three endotypes based on the presence of type 1, type 2, or type 3 inflammation. CRS endotypes can be influenced by age and geographic location. Clinical application however may be limited since endotyping current requires basic research laboratory support. Clinical symptoms may also predict inflammatory endotypes with smell loss being indicative of type 2 inflammation. Numbers of tissue and/or peripheral eosinophils as well as levels of IgE may predict disease severity in CRSwNP but not necessarily treatment responses. Unique clinical phenotypes or biomarkers are especially lacking that predict type 1 or type 3 inflammation in CRSwNP or type 1, type 2, or type 3 inflammation in CRSsNP.

CONCLUSION

While significant progress has been made in characterizing endotypes, phenotypes, and biomarkers in CRS, additional studies are needed to determine if and how these factors could assist physicians in providing more individualized clinical care.

Airway exposure to Staphylococcal enterotoxin type B (SEB) enhances the number and activity of bone marrow neutrophils via the release of multiple cytokines

BACKGROUND

The lung infections by Staphylococcus aureus are strongly associated with its ability to produce enterotoxins. However, little is known about the mechanisms underlying trafficking of bone marrow (BM) neutrophils during airway inflammation induced by Staphylococcal enterotoxin B (SEB). We therefore aimed to investigate the effects of mouse airways SEB exposure on BM neutrophil counts and its adhesive properties as well as on the release of cytokines/chemokines that orchestrate BM neutrophils trafficking to lung tissue.

METHODS

Male BALB/c mice were intranasally exposed to SEB (1 µg), and at 4, 16 and 24 h thereafter, BM, circulating blood, bronchoalveolar lavage (BAL) fluid and lung tissue were collected. BM neutrophils adhesion, MAC-1 and LFA1-α expressions (by flow cytometry) as well as measurement of cytokine and/or chemokines levels were assayed after SEB-airway exposure.

RESULTS

Prior exposure to SEB promoted a marked influx of neutrophils to BAL and lung tissue, which was accompanied by increased counts of BM immature neutrophils and blood neutrophilia. BM neutrophil expressions of LFA1-α and MAC-1 were unchanged by SEB exposure whereas a significant enhancement of adhesion properties to VCAM-1 was observed. The early phase of airway SEB exposure was accompanied by high levels of GM-CSF, G-CSF, IFN-γ, TNF-α and KC/CXCL1, while the latter phase by the equilibrated actions of SDF1-α and MIP-2.

CONCLUSION

Mouse airways exposure to SEB induces BM cytokines/chemokines release and their integrated actions enhance the adhesion of BM neutrophils leading to acute lung injury.

Sensitisation to staphylococcal enterotoxins and asthma severity: a longitudinal study in the EGEA cohort

INTRODUCTION

Evidence is accumulating that Staphylococcus aureus plays an important role as disease modifier in upper and lower airway diseases. Sensitisation to S. aureus enterotoxins (SEs) was associated with an increased risk of severe asthma in previous cross-sectional studies, but evidence from longitudinal studies is lacking. We aimed to assess associations between SE-sensitisation and the subsequent risk for asthma severity and exacerbations.

METHODS

This is a nested case-control study from the 20-year Epidemiological Study of the Genetics and Environment of Asthma (EGEA) cohort, including 225 adults (75 without asthma, 76 with mild asthma and 74 with severe asthma) in EGEA2 (2003-2007). For 173 of these individuals, SE-sensitisation was measured on samples collected 11 years earlier (EGEA1). Cross-sectional associations were conducted for EGEA1 and EGEA2. Longitudinal analyses estimated the association between SE-sensitisation in EGEA1 and the risk of severe asthma and asthma exacerbations assessed in the follow-up. Models were adjusted for sex, age, smoking, parental asthma/allergy and skin-prick test to house dust mite.

RESULTS

SE-sensitisation varied between 39% in controls to 58% and 76% in mild and severe asthma, respectively, in EGEA1. An adjusted cross-sectional association showed that SE-sensitisation was associated with an increased risk of severe, but not for mild asthma. SE-sensitisation in EGEA1 was associated with severe asthma (adjusted OR 2.69, 95% CI 1.18-6.15) and asthma exacerbations (adjusted OR 4.59, 95% CI 1.40-15.07) assessed 10-20 years later.

CONCLUSION

For the first time, this study shows that being sensitised to SEs is associated with an increased subsequent risk of severe asthma and asthma exacerbations.

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.

Filaggrin mutations increase allergic airway disease in childhood and adolescence through interactions with eczema and aeroallergen sensitization

BACKGROUND

Filaggrin loss-of-function (FLG-LOF) mutations are an established genetic cause of eczema. These mutations have subsequently been reported to increase the risk of aeroallergen sensitization and allergic airway disease. However, it is unclear whether FLG variants require both eczema and aeroallergen sensitization to influence airway disease development long-term outcomes.

OBJECTIVE

To examine the effects of FLG-LOF mutations on allergic airway disease outcomes, with eczema and aeroallergen sensitization as intermediate variables, using the Isle of Wight birth cohort.

METHODS

Study participants were evaluated at ages 1, 2, 4, 10 and 18 years to ascertain the development of allergic diseases (eczema, asthma and allergic rhinitis) and aeroallergen sensitization (determined by skin prick tests). FLG-LOF mutations were genotyped in 1150 subjects. To understand the complex associations between FLG mutations, intermediate variables (eczema and aeroallergen sensitization) and airway disease, path analysis was performed.

RESULTS

There were significant total effects of FLG-LOF mutations on both asthma and allergic rhinitis at all ages as well as on aeroallergen sensitization up till 10 years old. In the filaggrin-asthma analysis, a direct effect of FLG-LOF mutations was observed on early childhood eczema (age 1 and 2 years) (relative risk (RR) 2.01, 95% CI: 1.74-2.31, P < .001), and all significant indirect pathways on asthma outcomes passed through eczema at these ages. In contrast, for the filaggrin-rhinitis model, FLG-LOF mutations exerted significant direct effects on early eczema as well as rhinitis at 10 years (RR 1.99; 95% CI: 1.72-2.29, P = .002).

CONCLUSION

FLG-LOF mutations are a significant risk factor for later childhood asthma and rhinitis. However, the pathway to asthma is only through early childhood eczema while a direct effect was observed for childhood rhinitis.

A biodiversity hypothesis

Biodiversity hypothesis states that contact with natural environments enriches the human microbiome, promotes immune balance and protects from allergy and inflammatory disorders. We are protected by two nested layers of biodiversity, microbiota of the outer layer (soil, natural waters, plants, animals) and inner layer (gut, skin, airways). The latter inhabits our body and is colonized from the outer layer. Explosion of human populations along with cultural evolution is profoundly changing our environment and lifestyle. Adaptive immunoregulatory circuits and dynamic homeostasis are at stake in the newly emerged urban surroundings. In allergy, and chronic inflammatory disorders in general, exploring the determinants of immunotolerance is the key for prevention and more effective treatment. Loss of immunoprotective factors, derived from nature, is a new kind of health risk poorly acknowledged until recently. The paradigm change has been implemented in the Finnish allergy programme (2008-2018), which emphasized tolerance instead of avoidance. The first results are promising, as allergy burden has started to reduce. The rapidly urbanizing world is facing serious biodiversity loss with global warming, which are interconnected. Biodiversity hypothesis of health and disease has societal impact, for example, on city planning, food and energy production and nature conservation. It has also a message for individuals for health and well-being: take nature close, to touch, eat, breathe, experience and enjoy. Biodiverse natural environments are dependent on planetary health, which should be a priority also among health professionals.

Staphylococcus aureus internalization in mast cells in nasal polyps: Characterization of interactions and potential mechanisms

BACKGROUND

Chronic rhinosinusitis (CRS) with nasal polyps is a common chronic condition. The exact cause of nasal polyps remains unknown. Recently, we made the novel observation of intracellular localization of Staphylococcus aureus within mast cells in nasal polyps.

OBJECTIVE

This follow-up study aimed to further characterize interactions between S aureus and mast cells in this setting and elucidate potential internalization mechanisms with particular emphasis on the role of staphylococcal enterotoxin B (SEB).

METHODS

A prospective study was performed using an explant tissue model with ex vivo inferior turbinate mucosa obtained from patients with chronic rhinosinusitis with nasal polyps (n = 7) and patients without CRS (n = 5). Immunohistochemistry was used to characterize S aureus uptake into mast cells and investigate the effects of SEB on this process. An in vitro cell-culture model was used to investigate mast cell-S aureus interactions by using a combination of fluorescent in situ hybridization, confocal laser scanning microscopy, scanning electron microscopy, transmission electron microscopy, and proliferation assays.

RESULTS

S aureus was captured by extracellular traps and entered mast cells through phagocytosis. Proliferating intracellular S aureus led to the expansion and eventual rupture of mast cells, resulting in release of viable S aureus into the extracellular space. The presence of SEB appeared to promote internalization of S aureus into mast cells.

CONCLUSION

This study provides new insights into the interactions between S aureus and mast cells, including the internalization process, and demonstrates a prominent role for SEB in promoting uptake of the bacteria into these cells.

CD80/CD86 signaling contributes to the proinflammatory response of Staphylococcus aureus in the airway

It was posited that the initial host response to Staphylococcus aureus is a contributing factor in the pathogenesis of acute pneumonia. Having previously observed that T cells play a negative role in the pathogenesis of acute pneumonia to S. aureus the contribution of the CD80/CD86 pathway in pathogenesis was investigated. Mice lacking CD80 and CD86 had significantly improved survival in a mouse model of acute S. aureus pneumonia. This was accompanied by significant reductions in several proinflammatory cytokines, including TNF, MIP-2, IL-1β, IL-17 and IL-6, as well as increased numbers of viable alveolar macrophages. Early during infection reductions in cytokine production were evident and cytokine production in response to S. aureus in bone marrow derived macrophages showed decreases in TNF, KC, IL-1α and GM-CSF. Our data suggest that CD80/CD86 signaling plays a significant role in the initial inflammatory response to S. aureus in the airway and could be a potential acute target to reduce the initial inflammatory insult.

Interaction of host and Staphylococcus aureus protease-system regulates virulence and pathogenicity

Staphylococcus aureus causes various health care- and community-associated infections as well as certain chronic TH2 driven inflammatory diseases. It is a potent pathogen with serious virulence and associated high morbidity. Severe pathogenicity is accredited to the S. aureus secreted virulence factors such as proteases and host protease modulators. These virulence factors promote adhesion and invasion of bacteria through damage of tight junction barrier and keratinocytes. They inhibit activation and transmigration of various immune cells such as neutrophils (and neutrophil proteases) to evade opsono-phagocytosis and intracellular bacterial killing. Additionally, they protect the bacteria from extracellular killing by disrupting integrity of extracellular matrix. Platelet activation and agglutination is also impaired by these factors. They also block the classical as well as alternative pathways of complement activation and assist in spread of infection through blood and tissue. As these factors are exquisite factors of S. aureus mediated disease development, we have focused on review of diversification of various protease-system associated virulence factors, their structural building, diverse role in disease development and available therapeutic counter measures. This review summarises the role of protease-associated virulence factors during invasion and progression of disease.

In vitro characteristics of an airway barrier-disrupting factor secreted by Staphylococcus aureus

BACKGROUND

Staphylococcus aureus is a major contributor to the pathophysiology of chronic rhinosinusitis (CRS). Previous research has shown that S. aureus-secreted products disrupt the airway barrier.

METHODS

S. aureus ATCC 13565 and 25923 strains were grown at exponential, postexponential, and stationary phases. Microbial conditioned media (CM) was collected from the cultures and ultrafiltered (UF). Liquid chromatography-electrospray ionization tandem mass spectrometry (LC-ESI-MS/MS) was performed on the UF-CM. UF-CM was subjected to heat and protease treatment, size fractionation, and ultracentrifugation (UC) separation. Human nasal epithelial cells grown at air-liquid interface (HNEC-ALI) cultures were exposed to purified alpha hemolysin (Hla), staphylococcal enterotoxin A (SEA), lipoteichoic acid (LTA), and UF-CM. Barrier function outcomes were measured by transepithelial electrical resistance (TEER) and apparent permeability (Papp). UC fraction exposed cultures were subjected to immunofluorescence microscopy for tight junction (TJ) protein zonula occludens-1 (ZO-1).

RESULTS

LC-ESI-MS/MS identified 107 proteins, with Hla being most abundant. Hla, SEA, and LTA did not alter the HNEC-ALI barrier as measured by TEER or Papp. Barrier disruption caused by UF-CM peaked in the postexponential phase, was sensitive to heat and protease treatment, >30-kDa in size, and enriched in the UC fraction. HNEC-ALI exposed to UF-CM and UC demonstrated loss of ZO-1 localization.

CONCLUSION

These results suggest that the S. aureus factor responsible for TJ disruption in HNEC-ALI cultures is either a protein-macromolecule or a combination of secreted factors. The product is enriched in the UC fraction, suggesting it is associated with large structures such as membrane components or vesicles.

Allergic conversion of protective mucosal immunity against nasal bacteria in patients with chronic rhinosinusitis with nasal polyposis

BACKGROUND

Chronic rhinosinusitis with nasal polyposis (CRSwNP) is characterized by eosinophilic inflammation and polyposis at the nose and paranasal sinus and a high concentration of IgE in nasal polyps (NPs). The causative antigen and pathogenesis of CRSwNP remain unknown.

OBJECTIVE

We aimed to identify reactive allergens of IgE antibodies produced locally in NPs of patients with CRSwNP. We also attempted to unravel the differentiation pathway of IgE-producing B cells in NPs.

METHODS

IgE reactivity of patients with CRSwNP was investigated by characterizing single cell-derived mAbs. T-cell response against identified allergens was investigated in vitro. NP-infiltrating lymphocytes were characterized by using flow cytometry. Immunoglobulins expressed in NPs were analyzed by using high-throughput DNA sequencing for immunoglobulin.

RESULTS

About 20% of isolated IgE antibodies derived from NP-residing plasmablasts specifically recognized surface determinants of nasal bacteria, such as Staphylococcus aureus, Streptococcus pyogenes, and Haemophilus influenzae. A T_H2 response against S pyogenes was observed in patients with CRSwNP. Flow cytometric analysis revealed sizable germinal center B-like cell and plasmablast subsets expressing IgE on the cell surface in NPs. High-throughput DNA sequencing immunoglobulin analysis highlighted the clonal connectivity of IgE with IgG and IgA₁. The Iε-Cα₁ circle transcript was detected in NPs.

CONCLUSIONS

In patients with CRSwNP, nasal bacteria-reactive B cells differentiate into IgE-producing B cells through IgG/IgA₁-IgE class switching, suggesting that allergic conversion of the mucosal response against nasal bacteria underlies disease pathogenesis.

Immunochemical assay with monoclonal antibodies for detection of staphylococcal enterotoxin H

Staphylococcal enterotoxins cause food poisoning of various degrees of severity. For milk and meat products, there is a high probability of contamination with staphylococcal enterotoxin H (SEH). In this regard specific and sensitive methods are required to be developed for its detection and monitoring. In this work, the gene seh was expressed and a preparation of recombinant toxin was obtained. Using hybridoma technology, a panel of high-affinity monoclonal antibodies (mAbs) to SEH was produced. The antibodies were characterized and shown to have no cross-reactivity towards the main staphylococcal enterotoxins (A, B, C1, D, E, G and I). Based on these mAbs, a method for specific and quantitative detection of SEH was developed in the format of sandwich enzyme immunoassay (linear range, 0.2–3 ng/ml). All the mAbs produced revealed SEH by immunoblotting. Immunochemical analysis of the culture fluids of staphylococcal isolates obtained from the milk of mastitis-infected cows by immunoblotting and sandwich enzyme immunoassay demonstrated the conformity of these methods. Using the developed method, the toxin was revealed in blood serum and liquid food products practically to 100%. From non-liquid foods, it was shown to be extracted to a maximum with a buffer of pH 4.0–4.5.

Basis of Virulence in Enterotoxin-Mediated Staphylococcal Food Poisoning

The Staphylococcus aureus enterotoxins are a superfamily of secreted virulence factors that share structural and functional similarities and possess potent superantigenic activity causing disruptions in adaptive immunity. The enterotoxins can be separated into two groups; the classical (SEA-SEE) and the newer (SEG-SElY and counting) enterotoxin groups. Many members from both these groups contribute to the pathogenesis of several serious human diseases, including toxic shock syndrome, pneumonia, and sepsis-related infections. Additionally, many members demonstrate emetic activity and are frequently responsible for food poisoning outbreaks. Due to their robust tolerance to denaturing, the enterotoxins retain activity in food contaminated previously with S. aureus. The genes encoding the enterotoxins are found mostly on a variety of different mobile genetic elements. Therefore, the presence of enterotoxins can vary widely among different S. aureus isolates. Additionally, the enterotoxins are regulated by multiple, and often overlapping, regulatory pathways, which are influenced by environmental factors. In this review, we also will focus on the newer enterotoxins (SEG-SElY), which matter for the role of S. aureus as an enteropathogen, and summarize our current knowledge on their prevalence in recent food poisoning outbreaks. Finally, we will review the current literature regarding the key elements that govern the complex regulation of enterotoxins, the molecular mechanisms underlying their enterotoxigenic, superantigenic, and immunomodulatory functions, and discuss how these activities may collectively contribute to the overall manifestation of staphylococcal food poisoning.

House dust mites as potential carriers for IgE sensitization to bacterial antigens

Background

IgE reactivity to antigens from Gram‐positive and Gram‐negative bacteria is common in patients suffering from respiratory and skin manifestations of allergy, but the routes and mechanisms of sensitization are not fully understood. The analysis of the genome, transcriptome and microbiome of house dust mites (HDM) has shown that Staphylococcus aureus (S. aureus) and Escherichia coli (E. coli) species are abundant bacteria within the HDM microbiome. Therefore, our aim was to investigate whether HDM are carriers of bacterial antigens leading to IgE sensitization in patients suffering from atopic dermatitis.

Methods

Plasma samples from patients with AD (n = 179) were analysed for IgE reactivity to a comprehensive panel of microarrayed HDM allergen molecules and to S. aureus and E. coli by IgE immunoblotting. Antibodies specific for S. aureus and E. coli antigens were tested for reactivity to nitrocellulose‐blotted extract from purified HDM bodies, and the IgE‐reactive antigens were detected by IgE immunoblot inhibition experiments. IgE antibodies directed to bacterial antigens in HDM were quantified by IgE ImmunoCAP™ inhibition experiments.

Results

IgE reactivity to bacterial antigens was significantly more frequent in patients with AD sensitized to HDM than in AD patients without HDM sensitization. S. aureus and E. coli antigens were detected in immune‐blotted HDM extract, and the presence of IgE‐reactive antigens in HDM was demonstrated by qualitative and quantitative IgE inhibition experiments.

Conclusion

House dust mites (HDM) may serve as carriers of bacteria responsible for the induction of IgE sensitization to microbial antigens.

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.

Staphylococcus aureus enterotoxin sensitization is associated with allergic poly-sensitization and allergic multimorbidity in adolescents

BACKGROUND

Staphylococcus aureus (S. aureus) carriage and sensitization to S. aureus enterotoxins (SEs) have been associated with allergic diseases. From the Tromsø Study Fit Futures 2, we have previously shown an association between S. aureus carriage and severe allergic disease and allergic multimorbidity. However, the role of S. aureus carriage and SE sensitization on allergic multimorbidity and allergic sensitization is unclear.

OBJECTIVE

To study associations of both nasal S. aureus carriage and SE sensitization to allergic disease and allergic sensitization.

METHODS

A cross-sectional study of a school-based cohort in late adolescence (aged 18-19 years: The Tromsø Study Fit Futures 2). Self-reported allergic diseases were assessed using the Mechanisms of the Development of ALLergy questionnaire (MeDALL). Participants were tested for nasal S. aureus carriage, serum total IgE and specific IgE to SEs, and food and inhalant allergens.

RESULTS

A total of 868 participants were studied. Sensitization to at least one food or inhalant allergen was found in 319 of 765 (41.7%), and to at least one SE in 173 of 656 (26.2%) participants. SE sensitization, but not S. aureus carriage, was associated with poly-sensitization to food and inhalant allergens. SE-sensitized participants had higher median specific IgE to inhalant allergens (41.4 kU_A /L, IQR 10.1-118.4) compared to non-SE-sensitized participants (18.0 kU_A /L, IQR 5.5-48.6, P=.004), but not to food allergens. SE sensitization was associated with allergic multimorbidity.

CONCLUSION

Sensitization to SEs may play a role in the development of allergen poly-sensitization and allergic multimorbidity.

Endotype-driven treatment in chronic upper airway diseases

Rhinitis and rhinosinusitis are the two major clinical entities of chronic upper airway disease. Chronic rhinosinusitis (CRS) and allergic rhinitis (AR) affect respectively up to 10 and 30% of the total population, hence being associated with an important socio-economic burden. Different phenotypes of rhinitis and CRS have been described based on symptom severity and duration, atopy status, level of control, comorbidities and presence or absence of nasal polyps in CRS. The underlying pathophysiological mechanisms are diverse, with different, and sometimes overlapping, endotypes being recognized. Type 2 inflammation is well characterized in both AR and CRS with nasal polyps (CRSwNP), whereas type 1 inflammation is found in infectious rhinitis and CRS without nasal polyps (CRSsNP). The neurogenic endotype has been demonstrated in some forms of non-allergic rhinitis. Epithelial barrier dysfunction is shown in AR and CRSwNP. Emerging therapies are targeting one specific pathophysiological pathway or endotype. This endotype-driven treatment approach requires careful selection of the patient population who might benefit from a specific treatment. Personalized medicine is addressing the issue of providing targeted treatment for the right patient and should be seen as one aspect of the promising trend towards precision medicine. This review provides a comprehensive overview of the current state of endotypes, biomarkers and targeted treatments in chronic inflammatory conditions of the nose and paranasal sinuses.

Epigenetics and allergy: from basic mechanisms to clinical applications

Allergic diseases are on the rise in the Western world and well-known allergy-protecting and -driving factors such as microbial and dietary exposure, pollution and smoking mediate their influence through alterations of the epigenetic landscape. Here, we review key facts on the involvement of epigenetic modifications in allergic diseases and summarize and critically evaluate the lessons learned from epigenome-wide association studies. We show the potential of epigenetic changes for various clinical applications: as diagnostic tools, to assess tolerance following immunotherapy or possibly predict the success of therapy at an early time point. Furthermore, new technological advances such as epigenome editing and DNAzymes will allow targeted alterations of the epigenome in the future and provide novel therapeutic tools.

Staphylococcus aureus enterotoxin sensitization involvement and its association with the CysLTR1 variant in different asthma phenotypes

BACKGROUND

Sensitization to Staphylococcus aureus enterotoxin (SE) is a known risk factor for asthma susceptibility and severity. However, how SE sensitization is involved in asthma, particularly nonatopic asthma and/or late-onset asthma, remains uncertain.

OBJECTIVE

To clarify the involvement of SE sensitization in nonatopic and/or late-onset asthma and its association with a polymorphism of the cysteinyl leukotriene receptor 1 gene (CysLTR1), which was examined because CysLT signaling is closely associated with late-onset eosinophilic asthma.

METHODS

We assessed associations between sensitization to SE (A and/or B) and clinical indexes in 224 patients with asthma (mean age, 62.3 years; 171 women) from a cohort of the Kinki Hokuriku Airway Disease Conference, particularly those with nonatopic asthma (not sensitized to common aeroallergens) and/or late-onset asthma. Associations between SE sensitization and CysLTR1 polymorphism (rs2806489), a potential regulatory variant for atopic predisposition in women, were also assessed in a sex-stratified manner.

RESULTS

A total of 105 patients (47%) with asthma were sensitized to SE. Among patients with nonatopic asthma (n = 67) or with late-onset asthma (n = 124), those sensitized to SE had significantly higher serum total IgE and periostin levels than those not sensitized. In nonatopic patients, a rapid decrease in forced expiratory volume in 1 second was associated with SE sensitization. In women with asthma, rs2806489 was associated with sensitization to SEB and age at asthma onset.

CONCLUSION

SE sensitization contributes to T_H2 inflammation in nonatopic and/or late-onset asthma. In women with asthma, the CysLTR1 variant might be associated with sensitization to SEB and age at asthma onset.

Allergic disease and Staphylococcus aureus carriage in adolescents in the Arctic region of Norway

BACKGROUND

Allergic diseases are common chronic diseases in children and adolescents, but limited epidemiological data are available during transition into adulthood. Nasal Staphylococcus aureus carriage has been linked to increased prevalence of allergic disease. The objective of this study was to define the prevalence of allergic diseases in adolescents above the Arctic Circle in Northern Norway and to study the associations of S. aureus carriage with allergic diseases.

METHODS

A school-based cohort in late adolescence (18-19 years) was invited to participate in a cross-sectional study on lifestyle and health, and 868 attended (71.9%). Self-reported allergic disease and severity of eczema were assessed by Mechanisms of the Development of Allergy and Patient-Oriented Eczema Measure questionnaires. Participants were tested with spirometry and exhaled nitric oxide (FeNO) and swabbed for bacterial culture from nose and eczematous skin.

RESULTS

We found asthma, eczema, allergic rhinitis (AR), and nasal S. aureus carriage among 11.9%, 10.4%, 26.0%, and 51.3% of the participants, respectively, and 10.2% had allergic multimorbidity. Lifetime prevalence for any allergic disease was 45.1%. Reduced lung function and increased FeNO were found in 11.6% and 22.1% in participants with asthma, respectively. Nasal S. aureus carriage was associated with eczema, severe asthma, and severe AR. FeNO > 25 ppb was associated with both asthma and nasal S. aureus carriage.

CONCLUSION

Asthma, eczema, and AR are common among adolescents above the Arctic Circle in Norway. Allergic disease is associated with S. aureus carriage, but its role in the pathogenesis and severity is not established.

Aspirin-Exacerbated Respiratory Disease as an Endotype of Chronic Rhinosinusitis

Aspirin-Exacerbated Respiratory Disease (AERD) and Chronic Rhinosinusitis with Nasal Polyps (CRSwNP) are both characterized by the presence of chronic sinonasal inflammation and nasal polyps. Unlike in CRSwNP, AERD patients develop respiratory reactions following ingestion of COX-1 inhibitors. AERD patients also, on average, have worse upper respiratory disease with increased sinonasal symptoms, mucosal inflammation and requirements for revision sinus surgery when compared to CRSwNP patients. While no single genetic factor has been identified in either CRSwNP or AERD to date, differences in the metabolism of arachidonic acid as well as innate immune cell activation may uniquely contribute to AERD pathogenesis.

Viruses and bacteria in Th2-biased allergic airway disease

Allergic airway diseases are typically characterized by a type 2-biased inflammation. Multiple distinct viruses and bacteria have been detected in the airways. Recently, it has been confirmed that the microbiome of allergic individuals differs from that of healthy subjects, showing a close relationship with the type 2 response in allergic airway disease. In this review, we summarize the recent findings on the prevalence of viruses and bacteria in type 2-biased airway diseases and on the mechanisms employed by viruses and bacteria in propagating type 2 responses. The understanding of the microbial composition and postinfectious immune programming is critical for the reconstruction of the normal microflora and immune status in allergic airway diseases.

Antibodies and superantibodies in patients with chronic rhinosinusitis with nasal polyps

Background

Chronic rhinosinusitis with nasal polyps is associated with local immunoglobulin hyperproduction and the presence of IgE antibodies against Staphylococcus aureus enterotoxins (SAEs). Aspirin-exacerbated respiratory disease is a severe form of chronic rhinosinusitis with nasal polyps in which nearly all patients express anti-SAEs.

Objectives

We aimed to understand antibodies reactive to SAEs and determine whether they recognize SAEs through their complementarity-determining regions (CDRs) or framework regions.

Methods

Labeled staphylococcal enterotoxin (SE) A, SED, and SEE were used to isolate single SAE-specific B cells from the nasal polyps of 3 patients with aspirin-exacerbated respiratory disease by using fluorescence-activated cell sorting. Recombinant antibodies with “matched” heavy and light chains were cloned as IgG₁, and those of high affinity for specific SAEs, assayed by means of ELISA and surface plasmon resonance, were recloned as IgE and antigen-binding fragments. IgE activities were tested in basophil degranulation assays.

Results

Thirty-seven SAE-specific, IgG- or IgA-expressing B cells were isolated and yielded 6 anti-SAE clones, 2 each for SEA, SED, and SEE. Competition binding assays revealed that the anti-SEE antibodies recognize nonoverlapping epitopes in SEE. Unexpectedly, each anti-SEE mediated SEE-induced basophil degranulation, and IgG₁ or antigen-binding fragments of each anti-SEE enhanced degranulation by the other anti-SEE.

Conclusions

SEEs can activate basophils by simultaneously binding as antigens in the conventional manner to CDRs and as superantigens to framework regions of anti-SEE IgE in anti-SEE IgE-FcεRI complexes. Anti-SEE IgG₁s can enhance the activity of anti-SEE IgEs as conventional antibodies through CDRs or simultaneously as conventional antibodies and as “superantibodies” through CDRs and framework regions to SEEs in SEE–anti-SEE IgE-FcεRI complexes.

TNF and CD28 Signaling Play Unique but Complementary Roles in the Systemic Recruitment of Innate Immune Cells after Staphylococcus aureus Enterotoxin A Inhalation

Staphylococcus aureus enterotoxins cause debilitating systemic inflammatory responses, but how they spread systemically and trigger inflammatory cascade is unclear. In this study, we showed in mice that after inhalation, Staphylococcus aureus enterotoxin A rapidly entered the bloodstream and induced T cells to orchestrate systemic recruitment of inflammatory monocytes and neutrophils. To study the mechanism used by specific T cells that mediate this process, a systems approach revealed inducible and noninducible pathways as potential targets. It was found that TNF caused neutrophil entry into the peripheral blood, whereas CD28 signaling, but not TNF, was needed for chemotaxis of inflammatory monocytes into blood and lymphoid tissue. However, both pathways triggered local recruitment of neutrophils into lymph nodes. Thus, our findings revealed a dual mechanism of monocyte and neutrophil recruitment by T cells relying on overlapping and nonoverlapping roles for the noninducible costimulatory receptor CD28 and the inflammatory cytokine TNF. During sepsis, there might be clinical value in inhibiting CD28 signaling to decrease T cell-mediated inflammation and recruitment of innate cells while retaining bioactive TNF to foster neutrophil circulation.