RESUMEN
During surveillance of Staphylococcus aureus in lesions from patients with atopic dermatitis (AD), we isolated Staphylococcus argenteus, a species registered in 2011 as a new member of the genus Staphylococcus and previously considered a lineage of S. aureus. Genome sequence comparisons between S. argenteus isolates and representative S. aureus clinical isolates from various origins revealed that the S. argenteus genome from AD patients closely resembles that of S. aureus causing skin infections. We previously reported that 17%-22% of S. aureus isolated from skin infections produce staphylococcal enterotoxin Y (SEY), which predominantly induces T-cell proliferation via the T-cell receptor (TCR) Vα pathway. Complete genome sequencing of S. argenteus isolates revealed a gene encoding a protein similar to superantigen SEY, designated as SargEY, on its chromosome. Population structure analysis of S. argenteus revealed that these isolates are ST2250 lineage, which was the only lineage positive for the SEY-like gene among S. argenteus. Recombinant SargEY demonstrated immunological cross-reactivity with anti-SEY serum. SargEY could induce proliferation of human CD4+ and CD8+ T cells, as well as production of TNF-α and IFN-γ. SargEY showed emetic activity in a marmoset monkey model. SargEY and SET (a phylogenetically close but uncharacterized SE) revealed their dependency on TCR Vα in inducing human T-cell proliferation. Additionally, TCR sequencing revealed other previously undescribed Vα repertoires induced by SEH. SargEY and SEY may play roles in exacerbating the respective toxin-producing strains in AD. IMPORTANCE: Staphylococcus aureus is frequently isolated from active lesions of atopic dermatitis (AD) patients. We reported that 17%-22% of S. aureus isolated from AD patients produced a novel superantigen staphylococcal enterotoxin Y (SEY). Unlike many S. aureus superantigens that activate T cells via T-cell receptor (TCR) Vß, SEY activates T cells via TCR Vα and stimulates cytokine secretion. Staphylococcus argenteus was isolated from AD patients during the surveillance for S. aureus. Phylogenetic comparison of the genome indicated that the isolate was very similar to S. aureus causing skin infections. The isolate encoded a SEY-like protein, designated SargEY, which, like SEY, activated T cells via the TCR Vα. ST2250 is the only lineage positive for SargEY gene. ST2250 S. argenteus harboring a superantigen SargEY gene may be a novel staphylococcal clone that infects human skin and is involved in the exacerbation of AD.
Asunto(s)
Dermatitis Atópica , Enterotoxinas , Genoma Bacteriano , Staphylococcus , Superantígenos , Humanos , Dermatitis Atópica/microbiología , Dermatitis Atópica/inmunología , Superantígenos/genética , Superantígenos/inmunología , Staphylococcus/genética , Staphylococcus/inmunología , Staphylococcus/clasificación , Enterotoxinas/genética , Enterotoxinas/inmunología , Animales , Filogenia , Genómica , Secuenciación Completa del Genoma , Infecciones Estafilocócicas/microbiología , Infecciones Estafilocócicas/inmunologíaRESUMEN
Staphylococcal toxic shock syndrome (STSS) is a rare, yet potentially fatal disease caused by Staphylococcus aureus (S. aureus) enterotoxins, known as superantigens, which trigger an intense immune response. Our previous study demonstrated the protective effect of tofacitinib against murine toxin-induced shock and a beneficial effect against S. aureus sepsis. In the current study, we examined the effects of tofacitinib on T-cell response in peripheral blood using a mouse model of enterotoxin-induced shock. Our data revealed that tofacitinib suppresses the activation of both CD4+ and CD8+ T cells in peripheral blood. Furthermore, both gene and protein levels of Th1 cytokines were downregulated by tofacitinib treatment in mice with enterotoxin-induced shock. Importantly, we demonstrated that CD4+ cells, but not CD8+ cells, are pathogenic in mice with enterotoxin-induced shock. In conclusion, our findings suggest that tofacitinib treatment suppresses CD4+ T-cell activation and Th1 response, thereby aiding in protection against staphylococcal toxic shock in mice. This insight may guide the future development of novel therapies for STSS.
Asunto(s)
Linfocitos T CD4-Positivos , Activación de Linfocitos , Piperidinas , Pirimidinas , Choque Séptico , Infecciones Estafilocócicas , Células TH1 , Animales , Piperidinas/farmacología , Piperidinas/uso terapéutico , Células TH1/inmunología , Células TH1/efectos de los fármacos , Células TH1/metabolismo , Pirimidinas/farmacología , Pirimidinas/uso terapéutico , Choque Séptico/tratamiento farmacológico , Choque Séptico/inmunología , Choque Séptico/inducido químicamente , Ratones , Linfocitos T CD4-Positivos/inmunología , Linfocitos T CD4-Positivos/efectos de los fármacos , Linfocitos T CD4-Positivos/metabolismo , Activación de Linfocitos/efectos de los fármacos , Infecciones Estafilocócicas/tratamiento farmacológico , Infecciones Estafilocócicas/inmunología , Infecciones Estafilocócicas/microbiología , Enterotoxinas , Staphylococcus aureus/efectos de los fármacos , Citocinas/metabolismo , Linfocitos T CD8-positivos/efectos de los fármacos , Linfocitos T CD8-positivos/inmunología , Linfocitos T CD8-positivos/metabolismo , Ratones Endogámicos C57BL , Femenino , Modelos Animales de Enfermedad , Superantígenos/inmunologíaRESUMEN
BACKGROUND/AIMS: Sensitization to staphylococcal superantigens (SAgs) could contribute to asthma severity. However, its relevance with eosinophilic phenotype has not yet been clarified. This study aimed to investigate associations between serum specific IgE levels to SAg and eosinophilic airway inflammation in adult asthmatics. METHODS: The serum specific IgE levels to 3 SAgs, including staphylococcal enterotoxin A (SEA) and B (SEB), and toxic shock syndrome toxin-1 (TSST-1) were measured by ImmunoCAP in 230 adult asthmatic patients and 50 healthy controls (HCs). Clinical characteristics and laboratory parameters, including serum total/free IgE, and 2 eosinophil-activation markers, eosinophil cationic protein (ECP), and eosinophil-derived neurotoxin (EDN), were analyzed according to blood eosinophil counts (BEC; 150 cells/µL) and serum specific IgE levels to 3 SAgs (0.35 kU/L). RESULTS: Asthmatic patients showed higher serum specific IgE levels to 3 SAgs than HCs (p < 0.05 for all). The serum total/clinfree IgE levels were significantly higher in asthmatics with positive IgE responses to 3 SAgs than those without (p < 0.05 for all). There were no significant differences in clinical parameters including age, asthma severity, comorbidities, or smoking according to IgE responses to 3 SAgs. Patients with positive IgE responses to SEB (not to SEA/TSST-1) had higher serum specific IgE levels to house dust mites and ECP/EDN as well as higher BEC with positive correlations between serum SEB-specific IgE levels and BEC/ECP/EDN (p < 0.05 for all). CONCLUSION: These findings suggest that serum SEB-specific IgE levels could contribute to eosinophil activation as well as IgE production in adult asthma.
Asunto(s)
Asma , Enterotoxinas , Eosinófilos , Inmunoglobulina E , Fenotipo , Superantígenos , Humanos , Enterotoxinas/inmunología , Inmunoglobulina E/sangre , Masculino , Asma/inmunología , Asma/sangre , Asma/diagnóstico , Femenino , Persona de Mediana Edad , Adulto , Eosinófilos/inmunología , Estudios de Casos y Controles , Superantígenos/inmunología , Superantígenos/sangre , Biomarcadores/sangre , Anciano , Eosinofilia/inmunología , Eosinofilia/sangre , Eosinofilia/diagnóstico , Proteína Catiónica del Eosinófilo/sangre , Toxinas Bacterianas/inmunología , Toxinas Bacterianas/sangre , Neurotoxina Derivada del Eosinófilo/sangreRESUMEN
Staphylococcal Enterotoxin B (SEB), produced by Staphylococcus aureus (S. aureus), is a powerful superantigen that induces severe immune disruption and toxic shock syndrome (TSS) upon binding to MHC-II and TCR. Despite its significant impact on the pathogenesis of S. aureus, there are currently no specific therapeutic interventions available to counteract the mechanism of action exerted by this toxin. In this study, we have identified a human monoclonal antibody, named Hm0487, that specifically targets SEB by single-cell sequencing using PBMCs isolated from volunteers enrolled in a phase I clinical trial of the five-antigen S. aureus vaccine. X-ray crystallography studies revealed that Hm0487 exhibits high affinity for a linear B cell epitope in SEB (SEB138-147), which is located distantly from the site involved in the formation of the MHC-SEB-TCR ternary complex. Furthermore, in vitro studies demonstrated that Hm0487 significantly impacts the interaction of SEB with both receptors and the binding to immune cells, probably due to an allosteric effect on SEB rather than competing with receptors for binding sites. Moreover, both in vitro and in vivo studies validated that Hm0487 displayed efficient neutralizing efficacy in models of lethal shock and sepsis induced by either SEB or bacterial challenge. Our findings unveil an alternative mechanism for neutralizing the pathogenesis of SEB by Hm0487, and this antibody provides a novel strategy for mitigating both SEB-induced toxicity and S. aureus infection.
Asunto(s)
Anticuerpos Monoclonales , Anticuerpos Neutralizantes , Enterotoxinas , Enterotoxinas/inmunología , Enterotoxinas/antagonistas & inhibidores , Humanos , Anticuerpos Monoclonales/inmunología , Anticuerpos Neutralizantes/inmunología , Animales , Cristalografía por Rayos X , Staphylococcus aureus/inmunología , Infecciones Estafilocócicas/inmunología , Infecciones Estafilocócicas/prevención & control , Epítopos de Linfocito B/inmunología , Ratones , Choque Séptico/inmunología , Choque Séptico/prevención & control , Femenino , Leucocitos Mononucleares/inmunología , Vacunas Estafilocócicas/inmunología , Anticuerpos Antibacterianos/inmunología , Superantígenos/inmunologíaRESUMEN
Streptococcus pyogenes is a significant human pathogen, producing a range of virulence factors, including streptococcal pyrogenic exotoxin B (SpeB) that is associated with foodborne outbreaks. It was only known that this cysteine protease mediates cleavage of transmembrane proteins to permit bacterial penetration and is found in 25% of clinical isolates from streptococcal toxic shock syndrome patients with extreme inflammation. Its interaction with host and streptococcal proteins has been well characterized, but doubt remains about whether it constitutes a superantigen. In this study, for the first time it is shown that SpeB acts as a superantigen, similarly to other known superantigens such as staphylococcal enterotoxin A or streptococcal pyrogenic exotoxin type C, by inducing proliferation of murine splenocytes and cytokine secretion, primarily of interleukin-2 (IL-2), as shown by cytometric bead array analysis. IL-2 secretion was confirmed by enzyme-linked immunosorbent assay (ELISA) as well as secretion of interferon-γ. ELISA showed a dose-dependent relationship between SpeB concentration in splenocyte cells and IL-2 secretion levels, and it was shown that SpeB retains activity in milk pasteurized for 30 min at 63°C.
Asunto(s)
Proteínas Bacterianas , Proliferación Celular , Exotoxinas , Interferón gamma , Interleucina-2 , Bazo , Streptococcus pyogenes , Superantígenos , Animales , Interleucina-2/metabolismo , Superantígenos/inmunología , Superantígenos/metabolismo , Exotoxinas/metabolismo , Exotoxinas/inmunología , Interferón gamma/metabolismo , Interferón gamma/inmunología , Ratones , Bazo/microbiología , Bazo/citología , Bazo/inmunología , Proteínas Bacterianas/metabolismo , Proteínas Bacterianas/genética , Streptococcus pyogenes/inmunología , Streptococcus pyogenes/metabolismo , Femenino , Ratones Endogámicos BALB CRESUMEN
Staphylococcus aureus is a significant bacterial pathogen in both community and hospital settings, and the escalation of antimicrobial-resistant strains is of immense global concern. Vaccination is an inviting long-term strategy to curb staphylococcal disease, but identification of an effective vaccine has proved to be challenging. Three well-characterized, ubiquitous, secreted immune evasion factors from the staphylococcal superantigen-like (SSL) protein family were selected for the development of a vaccine. Wild-type SSL3, 7 and 11, which inhibit signaling through Toll-like receptor 2, cleavage of complement component 5 and neutrophil function, respectively, were successfully combined into a stable, active fusion protein (PolySSL7311). Vaccination of mice with an attenuated form of the PolySSL7311 protein stimulated significantly elevated specific immunoglobulin G and splenocyte proliferation responses to each component relative to adjuvant-only controls. Vaccination with PolySSL7311, but not a mixture of the individual proteins, led to a > 102 reduction in S. aureus tissue burden compared with controls after peritoneal challenge. Comparable antibody responses were elicited after coadministration of the vaccine in either AddaVax (an analog of MF59) or an Alum-based adjuvant; but only AddaVax conferred a significant reduction in bacterial load, aligning with other studies that suggest both cellular and humoral immune responses are necessary for protective immunity to S. aureus. Anti-sera from mice immunized with PolySSL7311, but not individual proteins, partially neutralized the functional activities of SSL7. This study confirms the importance of these SSLs for the survival of S. aureus in vivo and suggests that PolySSL7311 is a promising vaccine candidate.
Asunto(s)
Proteínas Bacterianas , Infecciones Estafilocócicas , Vacunas Estafilocócicas , Staphylococcus aureus , Superantígenos , Animales , Staphylococcus aureus/inmunología , Vacunas Estafilocócicas/inmunología , Superantígenos/inmunología , Infecciones Estafilocócicas/inmunología , Infecciones Estafilocócicas/prevención & control , Ratones , Proteínas Bacterianas/inmunología , Anticuerpos Antibacterianos/inmunología , Anticuerpos Antibacterianos/sangre , Femenino , Proteínas Recombinantes de Fusión/inmunología , Inmunoglobulina G/inmunología , Inmunoglobulina G/sangre , Estudios de Factibilidad , Vacunación , Antígenos Bacterianos/inmunología , Ratones Endogámicos BALB C , Adyuvantes InmunológicosRESUMEN
Bacterial T cell superantigens (SAgs) are a family of microbial exotoxins that function to activate large numbers of T cells simultaneously. SAgs activate T cells by direct binding and crosslinking of the lateral regions of MHC class II molecules on antigen-presenting cells with T cell receptors (TCRs) on T cells; these interactions alter the normal TCR-peptide-MHC class II architecture to activate T cells in a manner that is independent of the antigen specificity of the TCR. SAgs have well-recognized, central roles in human diseases such as toxic shock syndrome and scarlet fever through their quantitative effects on the T cell response; in addition, numerous other consequences of SAg-driven T cell activation are now being recognized, including direct roles in the pathogenesis of endocarditis, bloodstream infections, skin disease and pharyngitis. In this Review, we summarize the expanding family of bacterial SAgs and how these toxins can engage highly diverse adaptive immune receptors. We highlight recent findings regarding how SAg-driven manipulation of the adaptive immune response may operate in multiple human diseases, as well as contributing to the biology and life cycle of SAg-producing bacterial pathogens.
Asunto(s)
Receptores de Antígenos de Linfocitos T , Superantígenos , Linfocitos T , Superantígenos/inmunología , Humanos , Linfocitos T/inmunología , Receptores de Antígenos de Linfocitos T/inmunología , Antígenos Bacterianos/inmunología , Activación de Linfocitos/inmunología , Animales , Antígenos de Histocompatibilidad Clase II/inmunología , Bacterias/inmunologíaRESUMEN
Severe bacterial or viral infections can induce a state of immune hyperactivation that can culminate in a potentially lethal cytokine storm. The classic example is toxic shock syndrome, a life-threatening complication of Staphylococcus aureus or Streptococcus pyogenes infection, which is driven by potent toxins known as superantigens (SAgs). SAgs are thought to promote immune evasion via the promiscuous activation of T cells, which subsequently become hyporesponsive, and act by cross-linking major histocompatibility complex class II molecules on antigen-presenting cells to particular ß-chain variable (TRBV) regions of αß T cell receptors (TCRs). Although some of these interactions have been defined previously, our knowledge of SAg-responsive TRBV regions is incomplete. In this study, we found that CD4+ and CD8+ T cells expressing TRBV12-3/12-4+ TCRs were highly responsive to streptococcal pyrogenic exotoxin C (SpeC) and toxic shock syndrome toxin-1 (TSST-1). In particular, SpeC and TSST-1 specifically induced effector cytokine production and the upregulation of multiple coinhibitory receptors among TRBV12-3/12-4+ CD4+ and CD8+ memory T cells, and importantly, these biological responses were dependent on human leukocyte antigen (HLA)-DR. Collectively, these data provided evidence of functionally determinative and therapeutically relevant interactions between SpeC and TSST-1 and CD4+ and CD8+ memory T cells expressing TRBV12-3/12-4+ TCRs, mediated via HLA-DR.
Asunto(s)
Activación de Linfocitos , Células T de Memoria , Superantígenos , Humanos , Linfocitos T CD8-positivos/inmunología , Células T de Memoria/inmunología , Receptores de Antígenos de Linfocitos T , Superantígenos/inmunologíaRESUMEN
Staphylococcus aureus is a foremost bacterial pathogen responsible for a vast array of human diseases. Staphylococcal superantigens (SAgs) constitute a family of exotoxins from S. aureus that bind directly to major histocompatibility complex (MHC) class II and T cell receptors to drive extensive T cell activation and cytokine release. Although these toxins have been implicated in serious disease, including toxic shock syndrome, the specific pathological mechanisms remain unclear. Herein, we aimed to elucidate how SAgs contribute to pathogenesis during bloodstream infections and utilized transgenic mice encoding human MHC class II to render mice susceptible to SAg activity. We demonstrate that SAgs contribute to S. aureus bacteremia by massively increasing bacterial burden in the liver, and this was mediated by CD4+ T cells that produced interferon gamma (IFN-γ) to high levels in a SAg-dependent manner. Bacterial burdens were reduced by blocking IFN-γ, phenocopying SAg-deletion mutant strains, and inhibiting a proinflammatory response. Infection kinetics and flow cytometry analyses suggested that this was a macrophage-driven mechanism, which was confirmed through macrophage-depletion experiments. Experiments in human cells demonstrated that excessive IFN-γ allowed S. aureus to replicate efficiently within macrophages. This indicates that SAgs promote bacterial survival by manipulating the immune response to inhibit effective clearing of S. aureus Altogether, this work implicates SAg toxins as critical therapeutic targets for preventing persistent or severe S. aureus disease.
Asunto(s)
Interferón gamma/inmunología , Infecciones Estafilocócicas/inmunología , Superantígenos/inmunología , Animales , Bacteriemia , Enterotoxinas/inmunología , Exotoxinas/inmunología , Antígenos de Histocompatibilidad Clase II/inmunología , Humanos , Interferón gamma/metabolismo , Activación de Linfocitos/inmunología , Macrófagos/inmunología , Ratones , Ratones Endogámicos C57BL , Ratones Transgénicos , Receptores de Antígenos de Linfocitos T/inmunología , Staphylococcus aureus/patogenicidad , Linfocitos T/inmunología , Factores de Virulencia/inmunologíaRESUMEN
Streptococcus pyogenes (group A Streptococcus) is a globally disseminated and human-adapted bacterial pathogen that causes a wide range of infections, including scarlet fever. Scarlet fever is a toxin-mediated disease characterized by the formation of an erythematous, sandpaper-like rash that typically occurs in children aged 5 to 15. This infectious disease is caused by toxins called superantigens, a family of highly potent immunomodulators. Although scarlet fever had largely declined in both prevalence and severity since the late 19th century, outbreaks have now reemerged in multiple geographical regions over the past decade. Here, we review recent findings that address the role of superantigens in promoting a fitness advantage for S. pyogenes within human populations and discuss how superantigens may be suitable targets for vaccination strategies.
Asunto(s)
Antígenos Bacterianos/inmunología , Escarlatina/inmunología , Streptococcus pyogenes/inmunología , Superantígenos/inmunología , Adolescente , Niño , Preescolar , Femenino , Humanos , MasculinoRESUMEN
Influenza pandemics pose public health threats annually for lacking vaccine that provides cross-protection against novel and emerging influenza viruses. Combining conserved antigens that induce cross-protective antibody responses with epitopes that activate cross-protective T cell responses might be an attractive strategy for developing a universal vaccine. In this study, we constructed a recombinant protein named NMHC that consists of influenza viral conserved epitopes and a superantigen fragment. NMHC promoted the maturation of bone marrow-derived dendritic cells and induced CD4+ T cells to differentiate into Th1, Th2, and Th17 subtypes. Mice vaccinated with NMHC produced high levels of immunoglobulins that cross-bound to HA fragments from six influenza virus subtypes with high antibody titers. Anti-NMHC serum showed potent hemagglutinin inhibition effects to highly divergent group 1 (H1 subtype) and group 2 (H3 subtype) influenza virus strains. Furthermore, purified anti-NMHC antibodies bound to multiple HAs with high affinities. NMHC vaccination effectively protected mice from infection and lung damage when exposed to two subtypes of H1N1 influenza virus. Moreover, NMHC vaccination elicited CD4+ and CD8+ T cell responses that cleared the virus from infected tissues and prevented virus spread. In conclusion, this study provides proof of concept that NMHC vaccination triggers B and T cell immune responses against multiple influenza virus infections. Therefore, NMHC might be a candidate universal broad-spectrum vaccine for the prevention and treatment of multiple influenza viruses.
Asunto(s)
Virus de la Influenza A/inmunología , Vacunas contra la Influenza/inmunología , Infecciones por Orthomyxoviridae/prevención & control , Proteínas Recombinantes/inmunología , Animales , Linfocitos B/inmunología , Protección Cruzada , Epítopos/inmunología , Femenino , Glicoproteínas Hemaglutininas del Virus de la Influenza/inmunología , Inmunidad Celular , Subtipo H1N1 del Virus de la Influenza A/inmunología , Virus de la Influenza A/genética , Ratones Endogámicos BALB C , Superantígenos/inmunología , Linfocitos T/inmunologíaRESUMEN
B cell superantigens crosslink conserved domains of B cell receptors (BCRs) and cause dysregulated, polyclonal B cell activation irrespective of normal BCR-antigen complementarity. The cells typically succumb to activation-induced cell death, which can impede the adaptive immune response and favor infection. In the present study, we demonstrate that the fucose-binding lectin of Burkholderia ambifaria, BambL, bears functional resemblance to B cell superantigens. By engaging surface glycans, the bacterial lectin activated human peripheral blood B cells, which manifested in the surface expression of CD69, CD54 and CD86 but became increasingly cytotoxic at higher concentrations. The effects were sensitive to BCR pathway inhibitors and excess fucose, which corroborates a glycan-driven mode of action. Interactome analyses in a model cell line suggest BambL binds directly to glycans of the BCR and regulatory coreceptors. In vitro, BambL triggered BCR signaling and induced CD19 internalization and degradation. Owing to the lectin's six binding sites, we propose a BCR activation model in which BambL functions as a clustering hub for receptor glycans, modulates normal BCR regulation, and induces cell death through exhaustive activation.
Asunto(s)
Linfocitos B/metabolismo , Proteínas Bacterianas/metabolismo , Burkholderia/metabolismo , Lectinas/metabolismo , Polisacáridos/metabolismo , Receptores de Antígenos de Linfocitos B/metabolismo , Superantígenos/metabolismo , Linfocitos B/inmunología , Proteínas Bacterianas/inmunología , Sitios de Unión , Humanos , Lectinas/inmunología , Polisacáridos/inmunología , Unión Proteica , Receptores de Antígenos de Linfocitos B/inmunología , Transducción de Señal , Superantígenos/inmunologíaRESUMEN
Superantigens are unconventional antigens which recognise immune receptors outside their usual recognition sites e.g. complementary determining regions (CDRs), to elicit a response within the target cell. T-cell superantigens crosslink T-cell receptors and MHC Class II molecules on antigen-presenting cells, leading to lymphocyte recruitment, induction of cytokine storms and T-cell anergy or apoptosis among many other effects. B-cell superantigens, on the other hand, bind immunoglobulins on B-cells, affecting opsonisation, IgG-mediated phagocytosis, and driving apoptosis. Here, through a review of the structural basis for recognition of immune receptors by superantigens, we show that their binding interfaces share specific physicochemical characteristics when compared with other protein-protein interaction complexes. Given that antibody-binding superantigens have been exploited extensively in industrial antibody purification, these observations could facilitate further protein engineering to optimize the use of superantigens in this and other areas of biotechnology.
Asunto(s)
Células Presentadoras de Antígenos/metabolismo , Linfocitos B/metabolismo , Antígenos de Histocompatibilidad Clase II/metabolismo , Fragmentos de Inmunoglobulinas/metabolismo , Activación de Linfocitos , Receptores de Antígenos de Linfocitos T/metabolismo , Superantígenos/metabolismo , Linfocitos T/metabolismo , Animales , Anticuerpos/aislamiento & purificación , Células Presentadoras de Antígenos/inmunología , Apoptosis , Linfocitos B/inmunología , Linfocitos B/patología , Anergia Clonal , Síndrome de Liberación de Citoquinas/inmunología , Síndrome de Liberación de Citoquinas/metabolismo , Antígenos de Histocompatibilidad Clase II/inmunología , Humanos , Fragmentos de Inmunoglobulinas/inmunología , Ingeniería de Proteínas , Receptores de Antígenos de Linfocitos T/inmunología , Transducción de Señal , Superantígenos/inmunología , Linfocitos T/inmunología , Linfocitos T/patologíaRESUMEN
Atopic dermatitis (AD) is a condition affecting 30 million persons in the United States. AD patients are heavily infected with Staphylococcus aureus on the skin. A particularly severe form of AD is eczema herpeticum (ADEH), where the patients' AD is complicated by S. aureus and herpes simplex virus (HSV) infection. This study examined the S. aureus strains from 15 ADEH patients, provided blinded, and showed a high association of ADEH with strains that produce toxic shock syndrome toxin-1 (TSST-1; 73%) compared to 10% production by typical AD isolates from patients without EH and those from another unrelated condition, cystic fibrosis. The ADEH isolates produced the superantigens associated with TSS (TSST-1 and staphylococcal enterotoxins A, B, and C). This association may in part explain the potential severity of ADEH. We also examined the effect of TSST-1 and HSV-1 on human epithelial cells and keratinocytes. TSST-1 used CD40 as its receptor on epithelial cells, and HSV-1 either directly or indirectly interacted with CD40. The consequence of these interactions was chemokine production, which is capable of causing harmful inflammation, with epidermal/keratinocyte barrier disruption. Human epithelial cells treated first with TSST-1 and then HSV-1 resulted in enhanced chemokine production. Finally, we showed that TSST-1 modestly increased HSV-1 replication but did not increase viral plaque size. Our data suggest that ADEH is associated with production of the major TSS-associated superantigens, together with HSV reactivation. The superantigens plus HSV may damage the skin barrier by causing harmful inflammation, thereby leading to increased symptoms. IMPORTANCE Atopic dermatitis (eczema, AD) with concurrent herpes simplex virus infection (eczema herpeticum, ADEH) is a severe form of AD. We show that ADEH patients are colonized with Staphylococcus aureus that primarily produces the superantigen toxic shock syndrome toxin-1 (TSST-1); however, significantly but to a lesser extent the superantigens staphylococcal enterotoxins A, B, and C are also represented in ADEH. Our studies showed that TSST-1 uses the immune costimulatory molecule CD40 as its epithelial cell receptor. Herpes simplex virus (HSV) also interacted directly or indirectly with CD40 on epithelial cells. Treatment of epithelial cells with TSST-1 and then HSV-1 resulted in enhanced chemokine production. We propose that this combination of exposures (TSST-1 and then HSV) leads to opening of epithelial and skin barriers to facilitate potentially serious ADEH.
Asunto(s)
Toxinas Bacterianas/genética , Toxinas Bacterianas/metabolismo , Enterotoxinas/genética , Enterotoxinas/metabolismo , Herpesvirus Humano 1/metabolismo , Erupción Variceliforme de Kaposi/microbiología , Staphylococcus aureus/patogenicidad , Superantígenos/genética , Superantígenos/metabolismo , Toxinas Bacterianas/inmunología , Toxinas Bacterianas/farmacología , Antígenos CD40/inmunología , Quimiocinas/inmunología , Enterotoxinas/inmunología , Enterotoxinas/farmacología , Células Epiteliales/efectos de los fármacos , Células Epiteliales/inmunología , Células Epiteliales/microbiología , Células Epiteliales/virología , Células HaCaT , Herpesvirus Humano 1/inmunología , Humanos , Queratinocitos/efectos de los fármacos , Queratinocitos/inmunología , Queratinocitos/microbiología , Queratinocitos/virología , Staphylococcus aureus/metabolismo , Superantígenos/inmunología , Superantígenos/farmacologíaRESUMEN
The binding of nickel by immune proteins can manifest as Type IV contact dermatitis (Ni-specific T cells mediated) and less frequently as Type I hypersensitivity with both mechanisms remaining unknown to date. Since there are reports of patients co-manifesting the two hypersensitivities, a common mechanism may underlie both the TCR and IgE nickel binding. Focusing on Trastuzumab and Pertuzumab IgE variants as serendipitous investigation models, we found Ni-NTA interactions independent of Her2 binding to be due to glutamine stretches. These stretches are both Ni-inducible and in fixed pockets at the antibody complementarity-determining regions (CDRs) and framework regions (FWRs) of both the antibody heavy and light chains with influence from the heavy chain constant region. Comparisons with TCRs structures revealed similar interactions, demonstrating the possible underlying mechanism in selecting for Ni-binding IgEs and TCRs respectively. With the elucidation of the interaction, future therapeutic antibodies could also be sagaciously engineered to utilize such nickel binding for biotechnological purposes.
Asunto(s)
Hipersensibilidad/etiología , Inmunoglobulina E/inmunología , Níquel/inmunología , Superantígenos/inmunología , Anticuerpos Monoclonales Humanizados/química , Regiones Determinantes de Complementariedad , Células HEK293 , Humanos , Inmunoglobulina E/química , Cadenas Pesadas de Inmunoglobulina/química , Región Variable de Inmunoglobulina/química , Níquel/química , Receptores de Antígenos de Linfocitos T/inmunología , Trastuzumab/químicaRESUMEN
Staphylococcus aureus, a common cause of serious and often fatal infections, is well-armed with secreted factors that disarm host immune defenses. Highly expressed in vivo during infection, Staphylococcal protein A (SpA) is reported to also contribute to nasal colonization that can be a prelude to invasive infection. Co-evolution with the host immune system has provided SpA with an Fc-antibody binding site, and a Fab-binding site responsible for non-immune superantigen interactions via germline-encoded surfaces expressed on many human BCRs. We wondered whether the recurrent exposures to S. aureus commonly experienced by adults, result in the accumulation of memory B-cell responses to other determinants on SpA. We therefore isolated SpA-specific class-switched memory B cells, and characterized their encoding VH : VL antibody genes. In SpA-reactive memory B cells, we confirmed a striking bias in usage for VH genes, which retain the surface that mediates the SpA-superantigen interaction. We postulate these interactions reflect co-evolution of the host immune system and SpA, which during infection results in immune recruitment of an extraordinarily high prevalence of B cells in the repertoire that subverts the augmentation of protective defenses. Herein, we provide the first evidence that human memory responses are supplemented by B-cell clones, and circulating-antibodies, that bind to SpA determinants independent of the non-immune Fc- and Fab-binding sites. In parallel, we demonstrate that healthy individuals, and patients recovering from S. aureus infection, both have circulating antibodies with these conventional binding specificities. These findings rationalize the potential utility of incorporating specially engineered SpA proteins into a protective vaccine.
Asunto(s)
Linfocitos B/inmunología , Evolución Clonal/inmunología , Memoria Inmunológica , Proteína Estafilocócica A/inmunología , Linfocitos B/metabolismo , Biomarcadores , Humanos , Inmunofenotipificación , Modelos Biológicos , Unión Proteica/inmunología , Conformación Proteica , Proteína Estafilocócica A/química , Proteína Estafilocócica A/metabolismo , Staphylococcus aureus/inmunología , Relación Estructura-Actividad , Superantígenos/inmunologíaRESUMEN
Staphylococcal enterotoxins are one of the most important causative agents of food poisoning. These molecules function as both gastrointestinal toxins and superantigens (SAgs) which can simultaneously bind MHC-II and T cell receptor leading to a non-specific polyclonal T cell activation and massive proinflammatory cytokine release. Common symptoms include vomiting and diarrhea; however, in more severe cases, systemic dissemination may result in toxic shock syndrome and can be lethal in a few hours. Only small amounts of these heat-stable toxins are needed to cause the disease. Therefore, it is highly important to detect quickly low concentrations of SAgs in biological samples. In this work, we report a surface plasmon resonance (SPR)-based capture immunoassay for the detection of the SAg SEG. We analyzed the use of different amplification strategies. The SPR-based double-antibody sandwich approach could detect picomolar levels of SEG. The use of antibody-coated silica nanoparticles (AbSiNPs) as an alternative enhancing reagent also detected SEG in the picomolar range. Although AbSiNPs did not improve the limit of detection, for the same amount of SAg tested, AbSiNPs gave a higher response level than free antibodies. This work highlights the suitability of silica nanoparticles for signal amplification in SPR-based biosensors. Overall, SPR biosensors offer the capability for continuous real-time monitoring and high sensitivity that can be befitting for the detection of enterotoxins in food industries, laboratories and regulatory agencies.
Asunto(s)
Enterotoxinas/análisis , Inmunoensayo/métodos , Superantígenos/análisis , Resonancia por Plasmón de Superficie/métodos , Secuencia de Aminoácidos , Animales , Anticuerpos Antibacterianos , Técnicas Biosensibles/métodos , Materiales Biocompatibles Revestidos , Enterotoxinas/genética , Enterotoxinas/inmunología , Microbiología de Alimentos , Humanos , Límite de Detección , Nanopartículas , Conejos , Proteínas Recombinantes/genética , Proteínas Recombinantes/inmunología , Dióxido de Silicio , Intoxicación Alimentaria Estafilocócica/diagnóstico , Staphylococcus aureus/química , Staphylococcus aureus/genética , Staphylococcus aureus/inmunología , Superantígenos/genética , Superantígenos/inmunologíaRESUMEN
Staphylococcus aureus causes reiterative and chronic persistent infections. This can be explained by the formidable ability of this pathogen to escape immune surveillance mechanisms. Cells of S. aureus display the abundant staphylococcal protein A (SpA). SpA binds to immunoglobulin (Ig) molecules and coats the bacterial surface to prevent phagocytic uptake. SpA also binds and cross-links variable heavy 3 (VH3) idiotype (IgM) B cell receptors, promoting B cell expansion and the secretion of nonspecific VH3-IgM via a mechanism requiring CD4+ T cell help. SpA binding to antibodies is mediated by the N-terminal Ig-binding domains (IgBDs). The so-called region X, uncharacterized LysM domain, and C-terminal LPXTG sorting signal for peptidoglycan attachment complete the linear structure of the protein. Here, we report that both the LysM domain and the LPXTG motif sorting signal are required for the B cell superantigen activity of SpA in a mouse model of infection. SpA molecules purified from staphylococcal cultures are sufficient to exert B cell superantigen activity and promote immunoglobulin secretion as long as they carry intact LysM and LPXTG motif domains with bound peptidoglycan fragments. The LysM domain binds the glycan chains of peptidoglycan fragments, whereas the LPXTG motif is covalently linked to wall peptides lacking glycan. These findings emphasize the complexity of SpA interactions with B cell receptors.IMPORTANCE The LysM domain is found in all kingdoms of life. While their function in mammals is not known, LysM domains of bacteria and their phage parasites are associated with enzymes that cleave or remodel peptidoglycan. Plants recognize microbe-associated molecular patterns such as chitin via receptors endowed with LysM-containing ectodomains. In plants, such receptors play equally important roles in defense and symbiosis signaling. SpA of S. aureus carries a LysM domain that binds glycan strands of peptidoglycan to influence defined B cell responses that divert pathogen-specific adaptive immune responses.
Asunto(s)
Linfocitos B/inmunología , Peptidoglicano/inmunología , Peptidoglicano/metabolismo , Proteína Estafilocócica A/inmunología , Proteína Estafilocócica A/metabolismo , Staphylococcus aureus/inmunología , Superantígenos/inmunología , Inmunidad Adaptativa , Animales , Humanos , Activación de Linfocitos , Ratones , Ratones Endogámicos BALB C , Polisacáridos/inmunología , Polisacáridos/metabolismo , Unión Proteica , Receptores de Antígenos de Linfocitos B , Proteína Estafilocócica A/genéticaRESUMEN
Staphylococcus aureus is a common pathogen causing a wide range of infectious diseases in humans and animals. This bacterium secretes a variety of exoproteins, including toxins known as superantigens, such as toxic shock syndrome toxin-1 (TSST-1) and enterotoxins. Staphylococcal superantigen-like (SSL) proteins are a family of exoproteins showing structural similarities with superantigens but no superantigenic activity. This family is composed of 14 members (SSL1-SSL14), and recent studies have revealed that these members exhibit various immunomodulatory activities: e.g., inhibition of antibody and complement functions, impairment of leukocyte trafficking, modulation of receptor functions, inappropriate activation of immunocytes, and inhibition of blood coagulation. These activities have been proposed to contribute to immune evasion of the bacteria. The interactions between SSL proteins and their target molecules in the host immune system and the pathophysiological roles of SSL proteins in the bacterial infections are reviewed in this article.
Asunto(s)
Toxinas Bacterianas/inmunología , Enterotoxinas/inmunología , Exotoxinas/inmunología , Sistema Inmunológico/inmunología , Inmunomodulación , Infecciones Estafilocócicas/inmunología , Staphylococcus aureus/inmunología , Staphylococcus aureus/metabolismo , Superantígenos/inmunología , Animales , Coagulación Sanguínea , Humanos , Leucocitos/inmunología , RatonesRESUMEN
Staphylococcus aureus is a leading cause of significant morbidity and mortality and an enormous economic burden to public health worldwide. Infections caused by methicillin-resistant S. aureus (MRSA) pose a major threat as MRSA strains are becoming increasingly prevalent and multi-drug resistant. To this date, vaccines targeting surface-bound antigens demonstrated promising results in preclinical testing but have failed in clinical trials. S. aureus pathogenesis is in large part driven by immune destructive and immune modulating toxins and thus represent promising vaccine targets. Hence, the objective of this study was to evaluate the safety and immunogenicity of a staphylococcal 4-component vaccine targeting secreted bi-component pore-forming toxins (BCPFTs) and superantigens (SAgs) in non-human primates (NHPs). The 4-component vaccine proved to be safe, even when repeated vaccinations were given at a dose that is 5 to 10- fold higher than the proposed human dose. Vaccinated rhesus macaques did not exhibit clinical signs, weight loss, or changes in hematology or serum chemistry parameters related to the administration of the vaccine. No acute, vaccine-related elevation of serum cytokine levels was observed after vaccine administration, confirming the toxoid components lacked superantigenicity. Immunized animals demonstrated high level of toxin-specific total and neutralizing antibodies toward target antigens of the 4-component vaccine as well as cross-neutralizing activity toward staphylococcal BCPFTs and SAgs that are not direct targets of the vaccine. Cross-neutralization was also observed toward the heterologous streptococcal pyogenic exotoxin B. Ex vivo stimulation of PBMCs with individual vaccine components demonstrated an overall increase in several T cell cytokines measured in supernatants. Immunophenotyping of CD4 T cells ex vivo showed an increase in Ag-specific polyfunctional CD4 T cells in response to antigen stimulation. Taken together, we demonstrate that the 4-component vaccine is well-tolerated and immunogenic in NHPs generating both humoral and cellular immune responses. Targeting secreted toxin antigens could be the next-generation vaccine approach for staphylococcal vaccines if also proven to provide efficacy in humans.