Staphylococcal Superantigens Research Articles

Distribution of superantigenic toxin genes in Staphylococcus aureus isolates from milk samples of bovine subclinical mastitis cases in two major diary production regions of China

To evaluate the distribution of most known staphylococcal superantigen (SAg) genes in Staphylococcus aureus isolated from bovine mastitis cases, a genetic analysis of 15 SAg genes and genotypes was performed in a total of 283 S. aureus isolates collected from milk samples of cows with subclinical mastitis in two major diary production regions of China. Almost 65% of the isolates possessed at least one toxin gene. The most frequently found genes were sea (36.0%) followed by sei (31.8%), seg (31.4%) and selm (26.9%). The genes see, selk, or selo were not found in any of the isolates tested. Overall, 28 SAg genotypes were observed, among which the genotypes sea– seg– sei– selm, seg– sei– selm– seln, and sea– sed– selj predominated at the rate of 8.8%, 7.4%, and 6.7%, respectively. Marked geographical variations were noticed in the distribution of individual SAg genes and genotypes among S. aureus isolates from the two different regions. The relationship between toxin genotypes and toxin genes encoding profiles of mobile genetic elements (MGEs) was analyzed, revealing that majority of SAg genes were present in certain MGEs, which were in accordance with current knowledge about MGEs carrying those genes. However, some gene combinations suggest the possibility of the existence of variants or new types of MGEs.

Superantigen-mediated differentiation of bovine monocytes into dendritic cells

Although many effects of staphylococcal superantigens (SAg) on T cells are well established, less is known about their effects on APC. In this study, bovine PBMC were stimulated with a low dose of staphylococcal enterotoxin C1 (SEC1). The phenotype of adherent cells (Ac) derived from bovine PBMC cultured with SEC1 [SEC1-stimulated Ac (sAc)] for 192 h was CD14(-), CD68(-), CD163(-), dendritic cell (DC)-specific ICAM-3-grabbing nonintegrin(+), MHC class II (MHC II)(high), CD11a(low), CD11b(high), CD11c(high), and CD1b(high), suggesting these cells were dendritic cells (DC). SEC1 also induced transcription of the CXCL1, -2, and -3 family, CXCL6, CCL2, and CCL5 genes in sAc, which increased rapidly but returned to basal levels by 48 h. In contrast, increased transcription of CCL3, CCL8, and CXCL12, responsible for mononuclear cell migration and chronic inflammation, was sustained. In vitro cell migration assays showed vigorous migration of granulocytes, followed by migration of mononuclear cells. The autologous MLR showed that sAc induced a dose-dependent proliferation of CD4(+) T cells and an even stronger proliferation of CD8(+) T cells. This effect was inhibited or reduced by pretreatment with mAb to CD11b, MHC II, or MHC II plus CD18. These results indicate that stimulation of bovine PBMC by SAg induces differentiation of monocytes into DC.

Linking Innate and Adaptive Immunity: Human Vγ9Vδ2 T Cells Enhance CD40 Expression and HMGB-1 Secretion

γδ T cells play an important role in regulating the immune response to stress stimuli; however, the mean by which these innate lymphocytes fulfill this function remains poorly defined. The main subset of human peripheral blood γδ T cells responds to nonpeptidic antigens, such as isopentylpyrophosphate (IPP), a metabolite in the mevalonate pathway for both eukaryote and prokaryote cells. IPP-primed γδ T cells significantly augment the inflammatory response mediated by monocytes and αβ T cells to TSST-1, the staphylococcal superantigen that is the major causative agent of toxic shock syndrome. Here we show that the small pool of activated peripheral γδ T cells induces an early upregulation of CD40 on monocytes and the local release of High Mobility Group Box-1 (HMGB-1), the molecule designated as the late mediator of systemic inflammation. This finding provides a new basis for how γδ T cells may serve as influential modulators of both endogenous and exogenous stress stimuli.

IgE response to staphylococcal enterotoxins in adenoid tissues from atopic children

To evaluate local production of staphylococcal superantigen (SAg)-specific IgE in adenoid tissue and to compare its prevalence with that in the tonsil and serum, as well as its relationship with markers of allergic inflammation within adenoid tissue. Prospective randomized study. We recruited 18 atopic children who had rhinitis symptoms and were sensitized to more than one common aeroallergen, and 22 nonatopic children undergoing adenotonsillectomy. Immunoassays were performed using adenoid tissue homogenate to quantify the levels of three staphylococcal SAg-specific IgE (SEA, SEB, and TSST-1), total IgE, eosinophil cationic protein (ECP), mast cell tryptase, and soluble CD23. Three kinds of SAg-specific IgE were detected in the adenoid and tonsil tissues of atopic patients, but not in those of nonatopic patients. In atopic children, the prevalence of SEA-, SEB-, and TSST-1-specific IgE in adenoid tissues (61.1%, 27.8%, 33.3%, respectively) were higher than those in tonsil tissues (38.9%, 5.6%, 11.1%, respectively) and in sera (11.1%, 27.8%, 16.7%, respectively). Subjects with high SEA levels showed significantly higher serum and adenoid total IgE, with higher eosinophilia. Significant correlations were noted between SAg-specific IgE levels and tryptase levels in adenoid tissue. Local specific IgE response to staphylococcal SAgs, especially SEA may contribute to ongoing allergic inflammation in adenoid tissue from atopic children.

A broad-spectrum inhibitory peptide against staphylococcal enterotoxin superantigen SEA, SEB and SEC

The family of staphylococcal enterotoxin (SE) superantigen has been known to contribute to a broad-spectrum of diseases. In an attempt to screen the peptides with broad-spectrum inhibition against the superantigen activity of SEs, nine low-molecular peptides were designed on the basis of high conservative regions of amino acid sequences and structures of the SEs, the effects of these inhibitory peptides on the biological activity of SEs were detected by cellular and animal models, competition assay was used to detect the ability of the inhibitory peptide binding to MHC class II molecules. The results indicated that one dodecapeptide P72 possessed a broad-spectrum antagonist activity against superantigen SEA, SEB and SEC. The peptide P72 could protect mice from lethal toxic shock in the “two-hit” animal model. Competition experiment demonstrated peptide P72 could not bind to MHC class II molecules, which indicated the inhibitory activity of P72 may not due to binding to MHC class II. The peptide P72 with effective inhibition against the superantigen SEA, SEB and SEC may lead to a novel therapeutic modality in treatment of superantigen-mediated diseases.

Development of monoclonal antibodies to detect bovine FOXP3 in PBMCs exposed to a staphylococcal superantigen

The role of regulatory T cells (Tregs) is well documented in immune homeostasis and protection against autoimmune disease. Forkhead box protein 3 (FOXP3) has been shown to be essential for the development and function of Treg. Due to the lack of tools for FOXP3 detection in certain species, understanding the role of Treg in a variety of ruminant diseases has been hampered. In this study, we developed monoclonal antibodies (mAbs) against bovine FOXP3 using recombinant bovine FOXP3 lacking the forkhead domain as an immunogen. The specificity of the mAbs was confirmed by immunoblot and mass spectrometry. Expression of FOXP3 was induced in bovine PBMCs after 6 d of exposure to staphylococcal enterotoxin type C1 (SEC1) in vitro. Similar to findings in mice and humans, expression of FOXP3 was restricted to CD4+ CD25+ T cells. Transcriptional analysis of bovine TCR variable regions of the β chain (boVβ) showed that transcription of boVβ sequences reactive with SEC1 increased for 6 d, and then boVβ sequences non-reactive with SEC1 rapidly increased in the cultures. This indicates that induction of FOXP3+ CD4+ CD25+ Tregs by SEC1 is not Vβ restricted. The FOXP3 mAbs developed in this study will be useful in the further investigation of the role of Treg in staphylococcal pathogenesis in bovine mastitis and other ruminant diseases.

Staphylococcal toxin-induced T cell proliferation in atopic eczema correlates with increased use of superantigen-reactive Vbeta-chains in cutaneous lymphocyte-associated antigen (CLA)-positive lymphocytes.

Staphylococcal superantigens have been implicated in the pathogenesis of atopic dermatitis (AD). This may occur through superantigenic activation of T lymphocytes and their subsequent induction of the skin homing receptor CLA on activated cells. We investigated the proliferative responses of peripheral blood mononuclear cells (PBMC) from 10 patients with an infective exacerbation of AD and six normal controls to the staphylococcal superantigens, staphylococcal enterotoxin A and B (SEA, SEB) and toxic shock syndrome toxin-1 (TSST-1), and the mitogens phytohaemagglutinin (PHA) and concanavalin A (Con A). We also assessed CLA and T cell receptor (TCR) Vbeta-chain expression by immunofluorescence and flow cytometry before and after stimulation. PBMC from AD patients showed two-fold increased proliferation to SEA and SEB (P < 0.01) compared with normals, whereas the response to mitogenic stimulation was identical. Analysis of (TCR) Vbeta-chain expression demonstrated increased use of superantigen-reactive Vbeta families in freshly isolated PBMC in AD patients compared with controls. This pattern of Vbeta-chain expression was only observed in the CLA+ but not the total population of T cells. Furthermore, there was a positive correlation between the enhanced PBMC proliferative response and increased expression of superantigen-reactive Vbeta families in atopic patients. These data support the concept that superantigens are important in the pathogenesis of this common condition, and also provide evidence that the increased use of certain Vbeta families in circulating, CLA+, skin homing lymphocytes is of functional significance.

Neutralization of Multiple Staphylococcal Superantigens by a Single‐Chain Protein Consisting of Affinity‐Matured, Variable Domain Repeats

Staphylococcus aureus secretes various toxins that act as superantigens by stimulating a large fraction of the host's T cells. Toxin binding to variable domains of T cell receptor beta chains (Vbeta) leads to massive release of inflammatory molecules and potentially to toxic shock syndrome (TSS). Previously, we generated soluble forms of different Vbeta domains with a high affinity for binding superantigens. However, a broader spectrum antagonist is required for the neutralization of multiple toxins. In the present study, we expressed Vbeta domains in tandem as a single-chain protein and neutralized the clinically important superantigens staphylococcal enterotoxin B and TSS toxin-1 with a single agent.

Association of Staphylococcal Superantigen-Specific Immunoglobulin E with Mild and Moderate Atopic Dermatitis

To examine the frequency of allergic sensitization to staphylococcal superantigens in young children with mild to moderate atopic dermatitis (AD). AD severity was assessed with objective Scoring AD. Serum IgE to staphylococcal enterotoxin (SE) A, SEB, SEC, SED, and toxic shock syndrome toxin-1 were measured with ImmunoCAP. Comparisons between mild AD and moderate AD were performed by using logistic regressions. The prevalence of allergic sensitization to staphylococcal superantigens in patients with mild and moderate AD was 38% and 63%, respectively. Allergic sensitization to staphylococcal superantigens, particularly SEA and SED, was found to be associated with moderate AD, compared with mild AD. Our results suggest that allergic sensitization to staphylococcal superantigens is common even in young children with mild to moderate AD, and such sensitization may contribute to the disease severity of these patients.

The Role of Superantigens in Chronic Rhinosinusitis with Nasal Polyps

Recent reports suggest that staphylococcal exotoxins, acting as superantigens, activate T cells with subsequent massive proliferation, thereby contributing to the etiology of chronic rhinosinusitis with nasal polyps (CRSwNP). The objectives of this study are (1) to demonstrate directly the presence of staphylococcal exotoxins in nasal mucosa and sinonasal polyp tissue, and (2) provide indirect evidence of the effect of superantigens on the T cells expressing the target of superantigen, i.e., the β variable chain receptor (TCRBV) in polyp tissue and peripheral blood of patients with CRSwNP. Sinonasal polyp tissue and peripheral blood specimens were obtained from 37 patients with chronic rhinosinusitis (22 patients with bilateral nasal polyps, 15 without nasal polyps) and 12 normal subjects for comparative negative controls. Tissue specimens were assayed by enzyme-linked immunosorbent assay (ELISA) for the most common staphylococcal exotoxins (A–D) and toxic shock syndrome toxin type 1. Fresh tissue and blood samples were analyzed by flow cytometry to determine the expression of TCRBV. In the CRSwNP subjects 12 of 22 samples (54.54%) demonstrated reactivity for at least 1 staphylococcal exotoxin, while 2 of the 12 were positive for 2 toxins. There were no positive results in the CRS without nasal polyps or control groups. There was a clear trend of increased TCRBV expression in the ELISA-positive group both for tissue and blood specimens. Staphylococcal superantigens were present in the nasal cavity of patients with CRSwNP with a high percentage of TCRBV, which suggests the possibility of superantigens as etiological agents of CRSwNP.

Role of staphylococcal superantigens in upper airway disease

Chronic rhinosinusitis with nasal polyps often represents a chronic severe inflammatory disease of the upper airways and may serve as a model for lower airway diseases such as late-onset intrinsic asthma. Enterotoxins derived from Staphylococcus aureus have been implicated in the pathophysiology of nasal polyps as disease-modifying factors; recent findings using therapeutic proof-of-concept approaches support this hypothesis. Nasal polyps (chronic rhinosinusitis with nasal polyps) are characterized by a T-helper-2 dominated cytokine pattern that includes interleukin-5 and formation of immunoglobulin E. This is in contrast to chronic rhinosinusitis without polyps, which exhibits T-helper-1 biased cytokine release. It is now evident that the cytokine environment is decisive regarding the impact of S. aureus derived enterotoxins, which function as superantigens. S. aureus enterotoxin B further shifts the cytokine pattern in nasal polyps toward T-helper-2 cytokines (increases greater than twofold for interleukin-2, interleukin-4 and interleukin-5), but it disfavours the T-regulatory cytokines interleukin-10 and transforming growth factor-beta1. Furthermore, S. aureus derived enterotoxins influence local immunoglobulin synthesis and induce polyclonal immunoglobulin E production, which may contribute to severe inflammation via activation of mast cells. From this new understanding of chronic rhinosinusitis with nasal polyps, new therapeutic approaches emerge such as anti-interleukin-5, anti-immunoglobulin E, and antibiotic treatment. These may enlarge the nonsurgical armentarium.

Staphylococcal Toxic Shock Syndrome Toxin‐1 Induces the Translocation and Secretion of High Mobility Group‐1 Protein from Both Activated T Cells and Monocytes

High mobility group box-1 (HMGB-1) is a DNA-binding protein secreted by activated monocytes and has been identified as a key late mediator of endotoxic shock. We investigated the regulation of HMGB-1 in human peripheral blood mononuclear cells (PBMCs) following stimulation with the staphylococcal superantigen, toxic shock syndrome toxin-1 (TSST-1), and found that TSST-1, like LPS, induced the secretion of HMGB-1 from human PBMC. However, unlike monocyte-driven sepsis caused by endotoxin, translocation and secretion of HMGB-1 mediated by TSST-1 was dependent on the presence of both activated T cells and monocytes. Furthermore, we show that nuclear HMGB-1 is released from TSST-1 stimulated T cells. This finding presents a basis for investigating the potential of targeting HMGB-1 for the treatment of toxic shock syndrome, and provides further insight on the role of HMGB-1 in the cross-talk between activated monocytes and T cells.

Association of Specific IgE to Staphylococcal Superantigens with the Phenotype of Chronic Urticaria

It has been well established that bacterial superantigens lead to the induction and aggravation of chronic inflammatory skin diseases. We investigated the clinical significance of serum specific immunoglobulin E (lgE) to the staphylococcal superantigens staphylococcal enterotoxin A (SEA), staphylococcal enterotoxin B (SEB), and toxic shock syndrome toxin (TSST)-1 in patients with chronic urticaria (CU), focusing on the differences in these prevalences between aspirin-intolerant CU (AICU) and aspirin-tolerant CU (ATCU) patients. Aspirin sensitivity was confirmed by oral aspirin provocation test. There were 66 patients AICU and 117 patients ATCU in the study. Serum IgE antibodies specific for SEA, SEB, and TSST-1 were measured by the ImmunoCAP test and the patients were compared with 93 normal controls (NC). The prevalences of serum specific IgE to staphylococcal superantigens were significantly higher in CU than in NC patients (IgE to SEA, 13.7% vs. 5.4%; IgE to SEB, 12.0% vs. 4.3%; IgE to TSST-1, 18.0% vs. 6.5%; p< 0.05, respectively). The patients with specific IgE to SEA, SEB, and TSST-1 had higher serum total IgE levels and higher rates of atopy. Significant associations were noted between the prevalence of specific IgE to SEA and SEB and the HLA DQB1*0609 and DRB1*1302 alleles in the AICU group. We confirmed that a sub-population of patients with CU possesses serum IgE antibodies to SEA, SEB, and TSST-1. Particularly, the IgE immune response to TSST-1 is associated with aspirin sensitivity in CU patients.

PCR detection of Staphylococcal enterotoxins (SEs) N, O, P, Q, R, U, and survey of SE types in Staphylococcus aureus isolates from food-poisoning cases in Taiwan

Staphylococcal enterotoxins (SEs) are superantigenic toxins. They are five major classical types, i.e., SEA, SEB, SEC, SED, SEE, and new SEs or SE-like superantigens, such as SEG to SEU. Only the staphylococcal superantigens (SAgs) that induce emesis following oral administration in a monkey model are designated as SEs while other related toxins are called SE-like (SEl) superantigens. To survey the enterotoxin genotypes for S. aureus strains isolated from food-poisoning cases in Taiwan, we developed PCR primers specific for SEN, SEO, SEP, SEQ, SER, and SEU genes. The complete SE sequences and their expression potential for strains positive to sen, seo, sep, seq, ser, and seu specific primers were also determined. These strains were used as reference strains. With the PCR primers specific for all SEs or SAgs, including toxic shock syndrome toxin I (TSST-1), we assayed the genotypes of 147 S. aureus strains isolated from patients associated with staphylococcal food-poisoning outbreaks occurred during 2001–2003. For these147 strains, 135 (91.8%) were found positive for one or more SE or SAg genes. For classical enterotoxin and TSST-1 types, the major one was tsst-1 (59.1%) following by sea (29.2%), seb (19.7%), sec (6.8%), and sed (2.0%). For new SE and SAg types, the major one was sei (29.9%) and sep (27.9%) followed by, sek (16.3%), seo (14.3%), seu (14.2%), sem (11.6%), sen (10.9%), seq (10.9%), seh (8.2%), sel (6.8%), and ser (5.4%) etc. This report reveals the whole SE and SAg genotypes for S. aureus strains isolated from staphylococcal food-poisoning cases in Taiwan.

Role of Bacterial Pathogens in Atopic Dermatitis

The skin of atopic dermatitis (AD) patients exhibits a striking susceptibility to colonization and infection with Staphylococcus aureus. This review summarizes our understanding about the role of S. aureus in AD. Indeed, S. aureus colonization is both a cause and a consequence of allergic skin inflammation. The mechanisms that allergic skin inflammation of AD promotes the increase of S. aureus colonization include skin barrier dysfunction, increased synthesis of the extracellular matrix adhesins for S. aureus, and defective innate immune responses due to decreased production of endogenous antimicrobial peptides. On the other hand, the exotoxins secreted by S. aureus are superantigens. Staphylococcal superantigens (SsAgs) may penetrate the skin barrier and contribute to the persistence and exacerbation of allergic skin inflammation in AD through the stimulation of massive T cells, the role of allergens, direct stimulation of antigen-presenting cells and keratinocytes, the expansion of skin-homing cutaneous lymphocyte-associated antigen-positive T cells, and the augmentation of allergen-induced skin inflammation. SsAgs also induce corticosteroid resistance. In therapeutic interventions, anti-inflammatory therapy alone is very effective in reducing S. aureus colonization on the skin, but antibiotic treatment alone is unable to improve the allergic skin inflammation of AD. Therefore, we recommend the combination therapy of anti-inflammatory drugs and antibiotics in the AD patients with secondary bacterial infection, exacerbated AD, or poorly controlled AD. However, when AD is well controlled by anti-inflammatory drugs alone, we do not recommend the antibiotic therapy.

The role of superantigens of group A Streptococcus and Staphylococcus aureus in Kawasaki disease

Since the first suggestion of a superantigen hypothesis for Kawasaki disease over a decade ago, debate on the aetiology remains inconclusive. This article reviews recent publications that address the role of superantigens of group A Streptococcus and Staphylococcus aureus in the pathogenesis of Kawasaki disease. Over the past few years, new superantigens produced by group A Streptococcus and S. aureus have been increasingly identified, bringing the total known number to more than 30. Several studies on T-cell Vbeta repertoires and seroloepidemiology have demonstrated evidence for the involvement of single or multiple superantigens produced by the two pathogens. The associated superantigens differed in those studies, including streptococcal pyrogenic toxins A and C, staphylococcal enterotoxins A-C, and toxic shock syndrome toxin 1. These disparate findings suggest that the inflammation of Kawasaki disease does not result from a single agent but rather a final common inflammatory pathway in genetically susceptible individuals after numerous infectious agents. Certain staphylococcal and streptococcal superantigens are suggested to be responsible for the development of Kawasaki disease. A better understanding of the precise role of the causative agents will lead to accurate diagnosis, more targeted therapy and an improvement of coronary outcomes.

Higher Bcl‐2 levels decrease staphylococcal superantigen‐induced apoptosis of CD4+ T cells in atopic dermatitis

Staphylococcal superantigens (SsAgs) contribute to the persistence of allergic skin inflammation in atopic dermatitis (AD). The aims of this study were to (1) determine whether there are differences between AD patients and healthy subjects in SsAg-induced caspase-3 activation and SsAg-induced changes of anti-apoptotic protein Bcl-2 and Bcl-2 mRNA levels of CD4+ T cells; (2) investigate the effect of interleukin (IL)-4 on SsAg-induced caspase-3 activation and SsAg-induced changes of Bcl-2 and Bcl-2 mRNA levels of CD4+ T cells. Using immunofluorescence staining followed by flow cytometric analysis and real-time PCR, we analyzed peripheral blood mononuclear cells with or without staphylococcal enterotoxin B (SEB) stimulation in the presence or absence of recombinant IL-4 or anti-IL-4 neutralizing antibodies in 16 AD patients and 14 healthy subjects. SEB-reactive (TCRVbeta3+, Vbeta12+, and Vbeta17+) CD4+ T cells from AD patients were more resistant to SEB-induced caspase-3 activation and SEB-induced decrease of Bcl-2 and Bcl-2 mRNA than those from healthy subjects. Exogenously added IL-4 inhibited SEB-induced caspase-3 activation and SEB-induced decrease of Bcl-2 and Bcl-2 mRNA in SEB-reactive CD4+ T cells from healthy subjects. Inhibition of endogenous IL-4 by using anti-IL-4 neutralizing antibodies up-regulated SEB-induced caspase-3 activation and SEB-induced decrease of Bcl-2 and Bcl-2 mRNA in SEB-reactive CD4+ T cells from AD patients. Following SsAg stimulation, IL-4 produced by T cells in AD patients down-regulates SsAg-induced caspase-3 activation and apoptosis of CD4+ T cells through inhibiting the decrease of Bcl-2. This may impair deletion of SsAg-activated T cells and resolution of allergic skin inflammation.

Staphylococcal Enterotoxin-Like Toxins U2 and V, Two New Staphylococcal Superantigens Arising from Recombination within the Enterotoxin Gene Cluster

Staphylococcal Enterotoxin-Like Toxins U2 and V, Two New Staphylococcal Superantigens Arising from Recombination within the Enterotoxin Gene Cluster

The T cell response to staphylococcal superantigens is modulated by the bacterial cell wall (43.33)

Abstract Bacterial superantigens (SAgs) are pyrogenic exotoxins that cause oligoclonal T cell activation leading to toxic shock and death. The selective advantage of SAg expression by bacteria remains unknown. We hypothesized that the T cell response to SAg is modulated by the bacteria. If so, one should see intense T cell responses when SAg are introduced into the body alone, but not when the producing bacteria are also present. We examined the responses of primary T cells to a panel of pure staphylococcal SAg or in the presence of heat-killed bacteria. We found that the IL-2 response to SAg was inhibited by the presence of bacteria, while the TNF-? and IFN-? responses were not affected or were even increased. Such a modulation of T cell responses to SAg was mediated by TLR2/6 agonists but not by agonists of TLR1/2, TLR-9 or NOD proteins, involved activation of the NF-_B pathway, and was prevented by anti-TLR-2 blocking antibodies. At the cellular level, this modulation resulted from death of antigen-presenting cells (APCs) but not of T cells. Thus, we show that the response to SAg is modulated by TLR2/6 agonists from the bacterial cell wall. Such a modulation involves the induction of APC death that then limits the capacity of SAg to cause massive T cell activation. Our findings provide an explanation for the long-standing question of selective advantage of SAg expression, and point to novel therapeutic strategies for SAg-associated diseases.

Staphylococcal toxic-shock-syndrome-toxin-1 as a risk factor for disease relapse in Wegener's granulomatosis

Nasal carriage of Staphylococcus aureus constitutes a risk factor for disease exacerbation in Wegener's granulomatosis (WG). We hypothesized that staphylococcal superantigens (SAg) are a determinant of S. aureus-related risk for disease relapse in WG. In a retrospective longitudinal cohort study in 62 WG patients, we investigated the presence of the staphylococcal SAg genes sea, seb, sec, sed, see, tsst-1 and eta in S. aureus strains isolated from WG patients during an observation period of seven years. Subsequently, we assessed whether relapses of WG were associated with the presence of SAg-positive staphylococci. Of 1718 swab cultures analysed, 709 (41.2%) were S. aureus-positive. Fifty-one patients carried S. aureus, of whom 37 (72.5%) patients carried at least one SAg-positive S. aureus strain. Of the 709 S. aureus-positive cultures, 326 (46%) contained at least one SAg gene. Except for see, all assessed SAg genes were detected. sea was found most frequently, followed by sec, tsst-1 and eta and finally, by sed and seb. Using a multivariate, time-dependent Cox regression analysis we found that the presence of S. aureus was associated with relapses of WG (RR 3.2; 95% CI 1.2-8.4). The risk for relapse was modulated by the presence and type of SAg, with tsst-1 being associated with an increased risk for relapse (RR 13.3, 95% CI 4.2-42.6). The risk for relapse of WG increases with the presence of tsst-1-positive S. aureus. Eradication of tsst-1-positive S. aureus in WG may show whether disease relapses can be prevented.