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1.
PLoS Pathog ; 16(5): e1008393, 2020 05.
Artigo em Inglês | MEDLINE | ID: mdl-32433711

RESUMO

Infection with (SAg)-producing bacteria may precede or follow infection with or vaccination against influenza A viruses (IAVs). However, how SAgs alter the breadth of IAV-specific CD8+ T cell (TCD8) responses is unknown. Moreover, whether recall responses mediating heterosubtypic immunity to IAVs are manipulated by SAgs remains unexplored. We employed wild-type (WT) and mutant bacterial SAgs, SAg-sufficient/deficient Staphylococcus aureus strains, and WT, mouse-adapted and reassortant IAV strains in multiple in vivo settings to address the above questions. Contrary to the popular view that SAgs delete or anergize T cells, systemic administration of staphylococcal enterotoxin B (SEB) or Mycoplasma arthritidis mitogen before intraperitoneal IAV immunization enlarged the clonal size of 'select' IAV-specific TCD8 and reshuffled the hierarchical pattern of primary TCD8 responses. This was mechanistically linked to the TCR Vß makeup of the impacted clones rather than their immunodominance status. Importantly, SAg-expanded TCD8 retained their IFN-γ production and cognate cytolytic capacities. The enhancing effect of SEB on immunodominant TCD8 was also evident in primary responses to vaccination with heat-inactivated and live attenuated IAV strains administered intramuscularly and intranasally, respectively. Interestingly, in prime-boost immunization settings, the outcome of SEB administration depended strictly upon the time point at which this SAg was introduced. Accordingly, SEB injection before priming raised CD127highKLRG1low memory precursor frequencies and augmented the anamnestic responses of SEB-binding TCD8. By comparison, introducing SEB before boosting diminished recall responses to IAV-derived epitopes drastically and indiscriminately. This was accompanied by lower Ki67 and higher Fas, LAG-3 and PD-1 levels consistent with a pro-apoptotic and/or exhausted phenotype. Therefore, SAgs can have contrasting impacts on anti-IAV immunity depending on the naïve/memory status and the TCR composition of exposed TCD8. Finally, local administration of SEB or infection with SEB-producing S. aureus enhanced pulmonary TCD8 responses to IAV. Our findings have clear implications for superinfections and prophylactic vaccination.


Assuntos
Memória Imunológica/imunologia , Vírus da Influenza A/imunologia , Superantígenos/imunologia , Animais , Linfócitos T CD8-Positivos/imunologia , Epitopos/imunologia , Feminino , Humanos , Memória Imunológica/fisiologia , Vírus da Influenza A/metabolismo , Influenza Humana/imunologia , Influenza Humana/metabolismo , Ativação Linfocitária/imunologia , Camundongos , Camundongos Endogâmicos BALB C , Staphylococcus aureus/imunologia , Superantígenos/fisiologia , Superinfecção/imunologia , Vacinação
2.
PLoS One ; 15(2): e0228751, 2020.
Artigo em Inglês | MEDLINE | ID: mdl-32049976

RESUMO

BACKGROUND: Primary cutaneous CD30+ lymphoproliferative disorders (CD30CLPD) are the second most common type of cutaneous T cell lymphoma (CTCL) and include lymphomatoid papulosis (LyP) and primary cutaneous anaplastic large cell lymphoma (pcALCL). Case reports and small patient series suggest an association of CD30CLPD with atopic disorders. However, the prevalence of atopy in patients with CD30CLPD in retrospective studies depends on patients' recall which is not always reliable. More objective criteria of atopy include evidence of skin reactivity to allergens (positive prick test) and evidence of allergen-specific IgE in serum. This study was undertaken to test the hypothesis that atopy is prevalent in patients with CD30CLPD using serologic criteria of allergen-specific IgE antibodies to aeroallergens and Staphylococcal aureus enterotoxin superantigens (SSAgs). METHODS: We tested serum samples of CD30CLPD for common IgE-specific airborne allergens with the Phadiatop test, which if positive, is regarded as serologic evidence of atopy in adults. Sera were also tested for IgE antibodies reactive to three Staphylococcal enterotoxins with superantigenic properties (SSAg-IgE). Control sera were obtained from adult subjects evaluated for rhino-sinusitis and a negative Phadiatop test. Patients' history of an atopic disorder was obtained by retrospective chart review. FINDINGS: Nearly 50% of patients with the most common LyP types (A and C) had a positive Phadiatop test for allergic sensitization to common airborne allergens, and total serum IgE (IgE-t) was increased compared to non-atopic controls. At the IgE antibody concentration generally used to define serologic atopy (≥ 0.35 kUA/L), 8/31 (26%) samples of CD30CLPD and 7/28 (25%) samples of LyP were reactive to at least one SSAg-IgE compared to 3/52 (6%) control specimens (P = 0.016 and P = 0.028, respectively). TSST1-IgE was detected in 7 (23%) specimens of CD30CLPD, often together with SEB-IgE; SEA-IgE ≥ 0.35 kUA/L was not detected. For control specimens, TSST1-IgE exceeded the 0.35 kUA/L threshold in 3 (6%) specimens. CONCLUSIONS: Patients with LyP types A and C have serologic evidence of atopy against common airborne antigens and SSAgs when compared to control adult subjects who had rhino-sinusitis and a negative Phadiatop test for aero-IgEs. Serologic evidence of atopy exceeded that determined by LyP patients' personal history. The findings support our hypothesis that an atopic diathesis may contribute to the pathogenesis of the most common types of LyP (A and C).


Assuntos
Antígenos de Bactérias/imunologia , Papulose Linfomatoide/imunologia , Neoplasias Cutâneas/imunologia , Staphylococcus aureus/imunologia , Superantígenos/imunologia , Adolescente , Corticosteroides/farmacologia , Adulto , Idoso , Feminino , Humanos , Imunoglobulina E/imunologia , Papulose Linfomatoide/sangue , Masculino , Pessoa de Meia-Idade , Recidiva , Estudos Retrospectivos , Neoplasias Cutâneas/sangue , Fumar , Adulto Jovem
3.
Asian Pac J Allergy Immunol ; 38(1): 52-63, 2020 Mar.
Artigo em Inglês | MEDLINE | ID: mdl-30660176

RESUMO

BACKGROUND: Staphylococcal enterotoxin A (SEA) is a well-known superantigen and stimulates human peripheral blood mononuclear cells (PBMCs) involving in the pathogenesis of inflammatory disorders and cancer. OBJECTIVE: To better understand the biological activities of SEA and the possible intracellular mechanisms by which SEA plays its roles in conditions like staphylococcal inflammatory and/or autoimmune disorders and immunotherapy. METHODS: Recombinant SEA (rSEA) was expressed in a prokaryotic expression system and its effects on the cytokine and chemokine production was examined by Enzyme-linked Immunospot (ELISpot) Assay and ELISA analysis. RESULTS: In vitro experiments showed rSEA could significantly enhance secretion of a broad spectrum of cytokines and chemokines from PBMCs dose-dependently. Increased secretion of cytokines and chemokines from rSEA stimulated PBMCs was barely affected by C-C motif chemokine receptor 2 (CCR2) antagonist INCB3344. However, Src, ERK and STAT pathway inhibitors were able to successfully block the enhanced secretion of most of cytokines and chemokines produced by rSEA stimulated PBMCs. CONCLUSIONS: Our work suggested that rSEA serves as a potent stimulant of PBMCs, and induces the release of cytokines and chemokines through Src, ERK and STAT pathways upon a relatively independent network. Our work also strongly supported that Src, ERK and STAT signaling inhibitors could be effective therapeutic agents against diseases like toxic shock syndrome or infection by microbes resistant to antibiotics.


Assuntos
Quimiocinas/imunologia , Citocinas/imunologia , Enterotoxinas/imunologia , Leucócitos Mononucleares/imunologia , Transdução de Sinais , Adolescente , Adulto , Células Cultivadas , Feminino , Humanos , Sistema de Sinalização das MAP Quinases , Masculino , Pessoa de Meia-Idade , Proteínas Proto-Oncogênicas pp60(c-src)/metabolismo , Fatores de Transcrição STAT/metabolismo , Superantígenos/imunologia , Adulto Jovem
4.
Sci Adv ; 5(9): eaax3013, 2019 09.
Artigo em Inglês | MEDLINE | ID: mdl-31517054

RESUMO

Invasive streptococcal disease (ISD) and toxic shock syndrome (STSS) result in over 160,000 deaths each year. We modelled these in HLA-transgenic mice infected with a clinically lethal isolate expressing Streptococcal pyrogenic exotoxin (Spe) C and demonstrate that both SpeC and streptococcal M protein, acting cooperatively, are required for disease. Vaccination with a conserved M protein peptide, J8, protects against STSS by causing a dramatic reduction in bacterial burden associated with the absence of SpeC and inflammatory cytokines in the blood. Furthermore, passive immunotherapy with antibodies to J8 quickly resolves established disease by clearing the infection and ablating the inflammatory activity of the M protein, which is further enhanced by addition of SpeC antibodies. Analysis of 77 recent isolates of Streptococcus pyogenes causing ISD, demonstrated that anti-J8 antibodies theoretically recognize at least 73, providing strong support for using antibodies to J8, with or without antibodies to SpeC, as a therapeutic approach.


Assuntos
Anticorpos Antibacterianos/imunologia , Antígenos de Bactérias/imunologia , Proteínas da Membrana Bacteriana Externa/imunologia , Proteínas de Bactérias/imunologia , Proteínas de Transporte/imunologia , Exotoxinas/imunologia , Antígenos HLA/imunologia , Choque Séptico/imunologia , Infecções Estreptocócicas/imunologia , Streptococcus pyogenes/imunologia , Superantígenos/imunologia , Animais , Antígenos HLA/genética , Humanos , Camundongos , Camundongos Endogâmicos BALB C , Camundongos Transgênicos , Choque Séptico/genética , Infecções Estreptocócicas/genética
5.
Int J Mol Sci ; 20(16)2019 Aug 13.
Artigo em Inglês | MEDLINE | ID: mdl-31412561

RESUMO

Bacterial superantigens (SAgs) are exotoxins that promote a fulminant activation of the immune system. The subsequent intense release of inflammatory cytokines often results in hypotension, shock, and organ failure with high mortality rates. In the current paradigm, the direct and simultaneous binding of SAgs with T-cell receptor (TCR)-bearing Vß regions and conserved structures on major histocompatibility complex class II (MHC class II) on antigen-presenting cells (APCs) induces the activation of both cell types. However, by crosslinking MHC class II molecules, APCs can be activated by SAgs independently of T lymphocytes. Recently, we showed that streptococcal pyrogenic exotoxin A (SPEA) of Streptococcus pyogenes stimulates an immunogenic APC phenotype with upregulated costimulatory molecules and inflammatory cytokines. Additionally, we revealed that SPEA triggers immunosuppressive programs in monocytes that facilitate the accumulation of regulatory T cells (Tregs) in in vitro monocyte/CD4+ T-cell cocultures. Immunosuppressive factors include anti-inflammatory interleukin 10 (IL-10), co-inhibitory surface molecule programmed cell death 1 ligand 1 (PD-L1), and the inhibitory indoleamine 2,3-dioxygenase (IDO)/kynurenine effector system. In the present study, we investigated the underlying mechanism of SPEA-stimulated monocyte-mediated accumulation of Tregs. Blood-derived monocytes from healthy donors were stimulated with SPEA for 48 h (SPEA-monocytes). For the evaluation of SPEA-monocyte-mediated modulation of CD4+ T lymphocytes, SPEA was removed from the culture through extensive washing of cells before adding allogeneic CD3/CD28-activated T cells. Results: In coculture with allogeneic CD4+ T cells, SPEA-monocytes mediate apoptosis of CD4+Foxp3- lymphocytes and accumulation of CD4+Foxp3+ Tregs. PD-L1 and kynurenine are critically involved in the mediated cell death because blocking both factors diminished apoptosis and decreased the proportion of the CD25+/Foxp3+ Treg subpopulation significantly. Upregulation of PD-L1 and kynurenine as well as SPEA-monocyte-mediated effects on T cells depend on inflammatory IL-1ß. Our study shows that monocytes activated by SPEA mediate apoptosis of CD4+Foxp3- T effector cells through PD-L1 and kynurenine. CD4+Foxp3+ T cells are resistant to apoptosis and accumulate in SPEA-monocyte/CD4+ T-cell coculture.


Assuntos
Proteínas de Bactérias/imunologia , Comunicação Celular , Exotoxinas/imunologia , Cinurenina/metabolismo , Proteínas de Membrana/imunologia , Monócitos/imunologia , Monócitos/metabolismo , Linfócitos T Reguladores/imunologia , Linfócitos T Reguladores/metabolismo , Apresentação do Antígeno/imunologia , Células Apresentadoras de Antígenos/imunologia , Células Apresentadoras de Antígenos/metabolismo , Antígenos de Bactérias/imunologia , Biomarcadores , Humanos , Imunofenotipagem , Ativação Linfocitária/imunologia , Superantígenos/imunologia
6.
Arch Razi Inst ; 74(2): 157-164, 2019 06.
Artigo em Inglês | MEDLINE | ID: mdl-31232565

RESUMO

Staphylococcus aureus is a gram-positive coccus that, in specific conditions, is able to generate various diseases. By secreting different enterotoxins, this bacterium prepares the settings to attack the host; among these, enterotoxins A and B play the most important roles in food poisoning. This study was performed to trace the genes coding enterotoxins A and B in Staphylococcus aureus isolated from the clinic and poultry slaughterhouse. In addition, the present study analyzed the relation between the prevalence of these genes and resistance to erythromycin and tetracycline. This study was performed from October 2015 to December 2016. A total of 200 samples of noses and cloaca from broiler poultry farms in Ilam, Iran, were collected, including 150 samples from the slaughterhouse and 50 samples from the clinic isolated for separating Staphylococcus aureus. After bacterial culture and confirmation of biochemical tests, the samples were evaluated for the identification of Staphylococcus aureus and the resistance pattern to antibiotics regarding the presence of femA, tets, ermb, sea, and seb genes using the disk diffusion method and polymerase chain reaction test. Out of 200 tested samples, 112 strains of Staphylococcus aureus (56%) were identified from which 91 and 21 strains were associated with the poultry slaughterhouse and clinic, respectively, and all the samples were identified using biochemical tests. After the detection of femA gene as an exclusive gene for the identification of Staphylococcus aureus strain, 100 strains (50%) were confirmed to be contaminated with this bacterium. Out of 100 strains, 46%, 14%, and 5% possessed the genes coding enterotoxin A, the genes coding enterotoxin B, and both genes, respectively. The results of antibiotic tests showed that 85% and 86% of the examined strains were resistant to erythromycin and tetracycline, respectively. In the present study, the analysis performed using QuickCalcs software showed that the strains resistant to these two antibiotics possessing the sea gene were more prevalent than those possessing seb genes in the samples isolated from the poultry slaughterhouse. This comparison revealed that during the short period of broiler poultry farms growth, resistant strains were able to proliferate sea gene among the herd, and its prevalence increased until reaching into the slaughterhouse. This study showed that the relation between the genes resistant to erythromycin and tetracycline and the sea gene was close and significant.


Assuntos
Antibacterianos/farmacologia , Farmacorresistência Bacteriana/imunologia , Eritromicina/farmacologia , Staphylococcus aureus/imunologia , Superantígenos/imunologia , Tetraciclina/farmacologia , Animais , Galinhas , Enterotoxinas/imunologia , Irã (Geográfico)
7.
Mol Biol Rep ; 46(4): 4085-4094, 2019 Aug.
Artigo em Inglês | MEDLINE | ID: mdl-31087247

RESUMO

The aetiology of inflammatory myopathies is not clearly known. A predominance of activated Cd8+ T lymphocytes in inflammatory infiltrates has already been detected. Superantigens activate lymphocytes in an oligoclonal manner. In the present investigation, we investigated local effects after injection of the superantigen (Sag) Staphylococcus enterotoxin A (SEA) in the quadriceps femoris muscle of Lewis rats. Histopathology and gene expression profiling was performed after injection of SEA or saline (control group) after one, three and 10 days. Histology revealed focal myositis predominated by Cd8+ T lymphocytes with a perimysial, endomysial and perivascular distribution, peaking 3 days after SEA injection. Using DNA microarray analysis (Affymetrix Rat Genome 230 2.0) genes that were differentially over-expressed at least 15 times at days one, three or ten after SEA injection were further analysed. One day after SEA injection over-expressed genes were related to the immune response (e.g. Fcnb, CD8a) but also to cell proliferation, differentiation and migration (e.g. Mpp2). Three days after SEA injection, differentially overexpressed genes were mainly related to the immune reaction with a clear signature for a Cd8+ T lymphocyte response (e.g. Cd3d, Cd8, Prf1, Gzmb). Ten days after SEA injection, the differentially overexpressed genes were again associated with the immune reaction (e.g. Cd3d, Il2) but also with regenerative processes and wound healing (e.g. Tgfa, Tpm1, Ripply1). The inflammatory response induced by SEA in Lewis rats shares histological and molecular similarities to polymyositis in humans. Therefore, SEA induced myositis can be taken as a new and apt model for polymyositis.


Assuntos
Enterotoxinas/imunologia , Miosite/imunologia , Superantígenos/imunologia , Animais , Linfócitos T CD8-Positivos/efeitos dos fármacos , Antígenos de Histocompatibilidade Classe II , Peptídeos e Proteínas de Sinalização Intracelular , Ativação Linfocitária , Masculino , Proteínas de Membrana , Modelos Animais , Ratos , Ratos Endogâmicos Lew , Superantígenos/metabolismo
8.
Microb Pathog ; 133: 103543, 2019 Aug.
Artigo em Inglês | MEDLINE | ID: mdl-31102653

RESUMO

PURPOSE: Whole genome sequencing (WGS) analysis of Staphylococcus aureus is increasingly used in clinical practice. Although bioinformatics tools used in WGS analysis readily define the S. aureus virulome, the clinical value of this type of analysis is unclear. Here, virulence genes in S. aureus bacteremia (SAB) isolates were evaluated by WGS, with superantigens (SAgs) further evaluated by conventional PCR and functional assays, and results correlated with mortality. METHODS: 152 SAB isolates collected throughout 2015 at a large Minnesota medical center were studied and associated clinical data analyzed. Virulence genes were identified from previously-reported WGS data (https://doi.org/10.1371/journal.pone.0179003). SAg genes sea, seb, sec, sed, see, seg, seh, sei, sej, and tst were also assessed by individual PCR assays. Mitogenicity of SAgs was assessed using an in vitro proliferation assay with splenocytes from HLA-DR3 transgenic mice. RESULTS: Of the 152 SAB isolates studied, 106 (69%) were methicillin-susceptible S. aureus (MSSA). The number of deaths attributed and not attributed to SAB, and 30-day survivors were 24 (16%), 2 (1%), and 128 (83%), respectively. From WGS data, both MSSA and MRSA had high proportions of adhesion (>80%) and immune-evasion (>70%) genes. There was no difference in virulomes between survivor- and non-survivor-associated isolates. Although over 60% of SAB isolates produced functional SAgs, there were no differences in the distribution or prevalence of SAg genes between survivor- and non-survivor-associated isolates. CONCLUSION: In this study of one year of SAB isolates from a large medical center, the S. aureus virulome, as assessed by WGS, and also for SAgs using individual PCRs and phenotypic characterization, did not impact mortality.


Assuntos
Bacteriemia/microbiologia , Bacteriemia/mortalidade , Farmacorresistência Bacteriana/genética , Infecções Estafilocócicas/microbiologia , Infecções Estafilocócicas/mortalidade , Staphylococcus aureus/genética , Staphylococcus aureus/patogenicidade , Idoso , Idoso de 80 Anos ou mais , Animais , Bacteriemia/imunologia , Aderência Bacteriana/genética , Sequência de Bases , Proliferação de Células , Feminino , Antígeno HLA-DR3 , Humanos , Evasão da Resposta Imune/genética , Masculino , Staphylococcus aureus Resistente à Meticilina/genética , Camundongos , Camundongos Transgênicos , Pessoa de Meia-Idade , Minnesota , Reação em Cadeia da Polimerase , Infecções Estafilocócicas/imunologia , Superantígenos/genética , Superantígenos/imunologia , Virulência/genética , Fatores de Virulência/genética
9.
Int J Mol Sci ; 20(8)2019 Apr 12.
Artigo em Inglês | MEDLINE | ID: mdl-31013832

RESUMO

B cell superantigens, also called immunoglobulin superantigens, bind to the variable regions of either the heavy or light chain of immunoglobulins mirroring the lymphocyte-activating properties of classical T cell superantigens. Protein A of Staphylococcus aureus, protein L of Peptostreptococcus magnus, and gp120 of HIV are typical immunoglobulin superantigens. Mast cells are immune cells expressing the high-affinity receptor for IgE (FcεRI) and are strategically located in the human heart, where they play a role in several cardiometabolic diseases. Here, we investigated whether immunoglobulin superantigens induced the activation of human heart mast cells (HHMCs). Protein A induced the de novo synthesis of cysteinyl leukotriene C4 (LTC4) from HHMCs through the interaction with IgE VH3+ bound to FcεRI. Protein L stimulated the production of prostaglandin D2 (PGD2) from HHMCs through the interaction with κ light chains of IgE. HIV glycoprotein gp120 induced the release of preformed (histamine) and de novo synthesized mediators, such as cysteinyl leukotriene C4 (LTC4), angiogenic (VEGF-A), and lymphangiogenic (VEGF-C) factors by interacting with the VH3 region of IgE. Collectively, our data indicate that bacterial and viral immunoglobulin superantigens can interact with different regions of IgE bound to FcεRI to induce the release of proinflammatory, angiogenic, and lymphangiogenic factors from human cardiac mast cells.


Assuntos
Mastócitos/imunologia , Mastócitos/metabolismo , Miocárdio/imunologia , Miocárdio/metabolismo , Superantígenos/imunologia , Antígenos de Bactérias/imunologia , Antígenos Virais/imunologia , Biomarcadores , Liberação de Histamina , Humanos , Imunoglobulina E/imunologia , Imunoglobulina G/imunologia , Imunoglobulina M/imunologia , Infarto do Miocárdio/etiologia , Infarto do Miocárdio/metabolismo , Infarto do Miocárdio/patologia , Miocárdio/patologia
10.
Curr Allergy Asthma Rep ; 19(4): 21, 2019 03 11.
Artigo em Inglês | MEDLINE | ID: mdl-30859336

RESUMO

PURPOSE OF REVIEW: Staphylococcus aureus (S. aureus) is correlated with the development of persistent severe inflammatory disease of the upper airway including chronic rhinosinusitis with nasal polyps (CRSwNP). The presence of S. aureus is associated with atopic disease including allergic rhinitis and atopic dermatitis and is associated with poor outcomes. RECENT FINDINGS: Several different strains of S. aureus generate different toxins and gene products that can account for organism pathogenicity. S. aureus bacteria and its antigens shape the bacterial and fungal microbiome and the mucosal niche which generates host responses that can account for inflammation. The multiple disease phenotypes and molecular endotypes seen in CRSwNP can be characterized by T-helper cell environment within the inflammatory milieu, the presence of epithelial barrier dysfunction, aberrant eicosanoid metabolism, poor wound healing, and dysfunctional host-bacteria interactions which lead to recalcitrant disease and worse surgical outcomes. Understanding the pathomechanisms that S. aureus utilizes to promote nasal polyp formation, prolonged tissue inflammation, and bacterial dysbiosis are essential in our efforts to identify new therapeutic approaches to resolve this chronic inflammatory process.


Assuntos
Pólipos Nasais/microbiologia , Rinite Alérgica/microbiologia , Sinusite/microbiologia , Infecções Estafilocócicas/microbiologia , Staphylococcus aureus/patogenicidade , Antígenos de Bactérias/imunologia , Doença Crônica , Enterotoxinas/imunologia , Humanos , Pólipos Nasais/diagnóstico , Pólipos Nasais/imunologia , Rinite Alérgica/diagnóstico , Rinite Alérgica/imunologia , Sinusite/diagnóstico , Sinusite/imunologia , Infecções Estafilocócicas/diagnóstico , Infecções Estafilocócicas/imunologia , Staphylococcus aureus/imunologia , Superantígenos/imunologia
11.
Clin Exp Immunol ; 197(1): 83-94, 2019 07.
Artigo em Inglês | MEDLINE | ID: mdl-30815853

RESUMO

Streptococcal pyrogenic exotoxin (Spe) A expression is epidemiologically linked to streptococcal tonsillo-pharyngitis and outbreaks of scarlet fever, although the mechanisms by which superantigens confer advantage to Streptococcus pyogenes are unclear. S. pyogenes is an exclusively human pathogen. As the leucocyte profile of tonsil is unique, the impact of SpeA production on human tonsil cell function was investigated. Human tonsil cells from routine tonsillectomy were co-incubated with purified streptococcal superantigens or culture supernatants from isogenic streptococcal isolates, differing only in superantigen production. Tonsil cell proliferation was quantified by tritiated thymidine incorporation, and cell surface characteristics assessed by flow cytometry. Soluble mediators including immunoglobulin were measured using enzyme-linked immunosorbent assay. Tonsil T cells proliferated in response to SpeA and demonstrated typical release of proinflammatory cytokines. When cultured in the absence of superantigen, tonsil preparations released large quantities of immunoglobulin over 7 days. In contrast, marked B cell apoptosis and abrogation of total immunoglobulin (Ig)A, IgM, and IgG production occurred in the presence of SpeA and other superantigens. In SpeA-stimulated cultures, T follicular helper (Tfh) cells showed a reduction in C-X-C chemokine receptor (CXCR)5 (CD185) expression, but up-regulation of OX40 (CD134) and inducible T cell co-stimulator (ICOS) (CD278) expression. The phenotypical change in the Tfh population was associated with impaired chemotactic response to CXCL13. SpeA and other superantigens cause dysregulated tonsil immune function, driving T cells from Tfh to a proliferating phenotype, with resultant loss of B cells and immunoglobulin production, providing superantigen-producing bacteria with a probable survival advantage.


Assuntos
Proteínas de Bactérias/imunologia , Exotoxinas/imunologia , Proteínas de Membrana/imunologia , Tonsila Palatina/imunologia , Streptococcus pyogenes/imunologia , Imunidade Adaptativa , Antígenos de Bactérias/imunologia , Antígenos de Bactérias/toxicidade , Linfócitos B/imunologia , Linfócitos B/patologia , Proteínas de Bactérias/toxicidade , Morte Celular/imunologia , Proliferação de Células , Citocinas/metabolismo , Exotoxinas/toxicidade , Humanos , Imunoglobulinas/biossíntese , Técnicas In Vitro , Ativação Linfocitária , Proteínas de Membrana/toxicidade , Tonsila Palatina/patologia , Fenótipo , Infecções Estreptocócicas/imunologia , Infecções Estreptocócicas/patologia , Streptococcus pyogenes/patogenicidade , Superantígenos/imunologia , Superantígenos/toxicidade , Linfócitos T Auxiliares-Indutores/imunologia , Linfócitos T Auxiliares-Indutores/patologia
12.
Biochem Biophys Res Commun ; 511(2): 350-355, 2019 04 02.
Artigo em Inglês | MEDLINE | ID: mdl-30795864

RESUMO

Staphylococcal superantigen-like (SSL) protein is a family of exotoxins that consists of 14 SSLs, and the roles of several SSLs in immune evasion of the cocci have been revealed. However little is known whether they act as immune activators and are involved in inflammatory disorders such as atopic dermatitis. In this study we examined whether SSLs activate mast cells, the key player of local inflammation. SSL12 evoked the release of a granule enzyme ß-hexosaminidase from bone marrow derived mast cells (BMMCs) in the absence of IgE. The release of the granule enzyme caused by SSL12 was not accompanied with the leakage of a cytosolic enzyme lactate dehydrogenase (LDH), unlike staphylococcal δ-toxin that was reported to induce both the release of ß-hexosaminidase and the leakage of LDH from the cells, suggesting that SSL12 evokes the degranulation of mast cells without cell membrane damage. Furthermore SSL12 induced IL-6 and IL-13 in both mRNA and protein levels indicating that SSL12 induces de novo synthesis of the cytokines. Evans blue extravasation was elevated by the intradermal injection of SSL12, suggesting that SSL12 is also able to evoke local inflammation in vivo. These findings indicate the novel mast cell activating activity of SSLs, and SSL12 is likely an important factor in both initiation phase and effector phase of allergic and immune responses.


Assuntos
Mastócitos/microbiologia , Staphylococcus/imunologia , Superantígenos/imunologia , Animais , Degranulação Celular , Células Cultivadas , Citocinas/imunologia , Interações Hospedeiro-Patógeno , Mastócitos/imunologia , Mastócitos/fisiologia , Camundongos Endogâmicos BALB C , Camundongos Endogâmicos C57BL , Infecções Estafilocócicas/imunologia , Infecções Estafilocócicas/microbiologia
13.
Microbiol Spectr ; 7(1)2019 01.
Artigo em Inglês | MEDLINE | ID: mdl-30737912

RESUMO

Streptococcus pyogenes (i.e., the group A Streptococcus) is a human-restricted and versatile bacterial pathogen that produces an impressive arsenal of both surface-expressed and secreted virulence factors. Although surface-expressed virulence factors are clearly vital for colonization, establishing infection, and the development of disease, the secreted virulence factors are likely the major mediators of tissue damage and toxicity seen during active infection. The collective exotoxin arsenal of S. pyogenes is rivaled by few bacterial pathogens and includes extracellular enzymes, membrane active proteins, and a variety of toxins that specifically target both the innate and adaptive arms of the immune system, including the superantigens; however, despite their role in S. pyogenes disease, each of these virulence factors has likely evolved with humans in the context of asymptomatic colonization and transmission. In this article, we focus on the biology of the true secreted exotoxins of the group A Streptococcus, as well as their roles in the pathogenesis of human disease.


Assuntos
Toxinas Bacterianas/metabolismo , Exotoxinas/metabolismo , Infecções Estreptocócicas/patologia , Streptococcus pyogenes/imunologia , Streptococcus pyogenes/patogenicidade , Superantígenos/imunologia , Sequência de Aminoácidos/genética , Proteínas de Bactérias/metabolismo , Toxinas Bacterianas/genética , Humanos , Filogenia , Infecções Estreptocócicas/microbiologia , Streptococcus pyogenes/genética , Superantígenos/genética , Fatores de Virulência/metabolismo
14.
J Infect Dis ; 219(8): 1307-1317, 2019 04 08.
Artigo em Inglês | MEDLINE | ID: mdl-30418594

RESUMO

Superantigens (SAgs) released by common Gram-positive bacterial pathogens have been reported to delete, anergize, or activate mouse T cells. However, little is known about their effects on preexisting memory CD8+ T cell (TCD8) pools. Furthermore, whether SAgs manipulate human memory TCD8 responses to cognate antigens is unknown. We used a human peripheral blood mononuclear cell culture system and a nontransgenic mouse model in which the impact of stimulation by two fundamentally distinct SAgs, staphylococcal enterotoxin B and Mycoplasma arthritidis mitogen, on influenza virus- and/or cytomegalovirus-specific memory TCD8 could be monitored. Bacterial SAgs surprisingly expanded antiviral memory TCD8 generated naturally through infection or artificially through vaccination. Mechanistically, this was a T cell-intrinsic and T cell receptor ß-chain variable-dependent phenomenon. Importantly, SAg-expanded TCD8 displayed an effector memory phenotype and were capable of producing interferon-γ and destroying target cells ex vivo or in vivo. These findings have clear implications for antimicrobial defense and rational vaccine design.


Assuntos
Linfócitos T CD8-Positivos/imunologia , Superantígenos/imunologia , Adulto , Animais , Antígenos de Bactérias/imunologia , Enterotoxinas/imunologia , Feminino , Humanos , Memória Imunológica/imunologia , Vacinas contra Influenza/imunologia , Ativação Linfocitária/imunologia , Masculino , Camundongos , Camundongos Endogâmicos BALB C , Orthomyxoviridae/imunologia , Adulto Jovem
15.
MAbs ; 11(2): 411-421, 2019.
Artigo em Inglês | MEDLINE | ID: mdl-30526311

RESUMO

A new modality in antibody engineering has emerged in which the antigen affinity is designed to be pH dependent (PHD). In particular, combining high affinity binding at neutral pH with low affinity binding at acidic pH leads to a novel antibody that can more effectively neutralize the target antigen while avoiding antibody-mediated antigen accumulation. Here, we studied how the in vivo pharmacokinetics of the superantigen, Staphylococcal enterotoxin B (SEB), is affected by an engineered antibody with pH-dependent binding. PHD anti-SEB antibodies were engineered by introducing mutations into a high affinity anti-SEB antibody, 3E2, by rational design and directed evolution. Three antibody mutants engineered in the study have an affinity at pH 6.0 that is up to 68-fold weaker than the control antibody. The pH dependency of each mutant, measured as the pH-dependent affinity ratio (PAR - ratio of affinity at pH 7.4 and pH 6.0), ranged from 6.7-11.5 compared to 1.5 for the control antibody. The antibodies were characterized in mice by measuring their effects on the pharmacodynamics and pharmacokinetics (PK) of SEB after co-administration. All antibodies were effective in neutralizing the toxin and reducing the toxin-induced cytokine production. However, engineered PHD antibodies led to significantly faster elimination of the toxin from the circulation than wild type 3E2. The area under the curve computed from the SEB PK profile correlated well with the PAR value of antibody, indicating the importance of fine tuning the pH dependency of binding. These results suggest that a PHD recycling antibody may be useful to treat intoxication from a bacterial toxin by accelerating its clearance.


Assuntos
Anticorpos Monoclonais/química , Anticorpos Monoclonais/imunologia , Enterotoxinas/imunologia , Engenharia de Proteínas/métodos , Animais , Afinidade de Anticorpos , Concentração de Íons de Hidrogênio , Camundongos , Superantígenos/imunologia
16.
Toxins (Basel) ; 10(11)2018 Nov 06.
Artigo em Inglês | MEDLINE | ID: mdl-30404186

RESUMO

During severe bacterial infections, death and disease are often caused by an overly strong immune response of the human host. Acute toxic shock is induced by superantigen toxins, a diverse set of proteins secreted by Gram-positive staphylococcal and streptococcal bacterial strains that overstimulate the inflammatory response by orders of magnitude. The need to protect from superantigen toxins led to our discovery that in addition to the well-known MHC class II and T cell receptors, the principal costimulatory receptor, CD28, and its constitutively expressed coligand, B7-2 (CD86), previously thought to have only costimulatory function, are actually critical superantigen receptors. Binding of the superantigen into the homodimer interfaces of these costimulatory receptors greatly enhances B7-2/CD28 engagement, leading to excessive pro-inflammatory signaling. This finding led to the design of short receptor dimer interface mimetic peptides that block the binding of superantigen and thus protect from death. It then turned out that such a peptide will protect also from Gram-negative bacterial infection and from polymicrobial sepsis. One such CD28 mimetic peptide is advancing in a Phase 3 clinical trial to protect from lethal wound infections by flesh-eating bacteria. These host-oriented therapeutics target the human immune system itself, rendering pathogens less likely to become resistant.


Assuntos
Toxinas Bacterianas/imunologia , Antígenos CD28/imunologia , Desenvolvimento de Medicamentos , Superantígenos/imunologia , Animais , Humanos
17.
Front Immunol ; 9: 2011, 2018.
Artigo em Inglês | MEDLINE | ID: mdl-30283436

RESUMO

Staphylococcus aureus is a common commensal and frequent opportunistic pathogen that causes invasive infections that often recur. Co-evolution with the host has led to the development of toxins that affect diverse immune cell types. Recent reports have highlighted the contributions of staphylococcal protein A (SpA). This small oligomeric secreted protein contains 4-5 homologous domains with two distinct immunoglobulin-binding sites; one for IgG Fc domains, while a separate site binds an evolutionarily conserved surface on Fab encoded by VHIII clan related genes. The Fab-binding site has been implicated in in vivo supraclonal VHIII-BCR targeted B-cell depletion by an activation induced death pathway. Yet the concept of a superantigen for B lymphocytes poses a seeming paradox. Unlike TCR that are expressed only in a membrane-associated form, BCR are expressed in both a membrane BCR form and in secreted Ig forms, which permeate virtually every part of the body at high levels. We therefore asked, why circulating immunoglobulin do not block the superantigen properties of SpA? Herein, we show that soluble IgG molecules are not in vivo inhibitors of these B-cell superantigen effects but are instead essential for potentiating these properties. We also show that the Fc subclass of circulating IgG is an indirect critical determinant of the B-cell superantigen effect. In contrast, host FcγR and complement are not required for SpA mediated in vivo B-cell depletion. Unexpectedly, after VHIII-IgG2a pretreatment SpA challenge resulted in fatal anaphylactic reactions, which we speculate may have involved FcγR interactions with mast cells and basophils. Cumulatively, our findings illuminate a cunning and potent molecular strategy by which a bacterial toxin effectively confounds the contributions of host B-lymphocytes to immune defenses.


Assuntos
Linfócitos B/imunologia , Imunoglobulina G/imunologia , Proteína Estafilocócica A/imunologia , Superantígenos/imunologia , Animais , Linfócitos B/metabolismo , Sítios de Ligação , Células Cultivadas , Fragmentos Fab das Imunoglobulinas/imunologia , Fragmentos Fab das Imunoglobulinas/metabolismo , Imunoglobulina G/metabolismo , Camundongos Endogâmicos C57BL , Camundongos Knockout , Camundongos Transgênicos , Receptores de Antígenos de Linfócitos B/genética , Receptores de Antígenos de Linfócitos B/imunologia , Receptores de Antígenos de Linfócitos B/metabolismo , Proteína Estafilocócica A/genética , Proteína Estafilocócica A/metabolismo , Superantígenos/metabolismo
18.
Monoclon Antib Immunodiagn Immunother ; 37(5): 212-217, 2018 Nov.
Artigo em Inglês | MEDLINE | ID: mdl-30362929

RESUMO

Staphylococcus aureus secretes a family of exoproteins structurally homologous to bacterial superantigens, such as toxic shock syndrome toxin-1 (TSST-1), and those exoproteins are thus called staphylococcal superantigen-like proteins (SSLs). Recent studies have revealed that SSLs play roles in evasion of the host defense by disturbing host immune responses. We previously reported that staphylococcal superantigen-like protein 5 (SSL5; a member of the SSL family) inhibited matrix metalloproteinase-9 (MMP-9), which is crucial for leukocyte recruitment to sites of infection. In this study, we established a mouse hybridoma clone (30G5C) producing a monoclonal antibody specific for SSL5. In immunoblotting analysis using recombinant His-tagged SSL1 to SSL14 (His-SSLs), the antibody was found to specifically recognize SSL5 without crossreactivity with other His-SSLs. The antibody bound to the C-terminal region of SSL5 (ß-grasp domain), but did not interfere with the binding of SSL5 to MMP-9, suggesting that this antibody is useful for identification of SSL5-producing S. aureus and screening for inhibitors of the SSL5/MMP-9 complex formation.


Assuntos
Anticorpos Monoclonais/imunologia , Proteínas de Bactérias/imunologia , Staphylococcus aureus/imunologia , Animais , Anticorpos Monoclonais/biossíntese , Toxinas Bacterianas/imunologia , Enterotoxinas/imunologia , Humanos , Camundongos , Ligação Proteica , Staphylococcus aureus/patogenicidade , Superantígenos/imunologia
19.
Am J Rhinol Allergy ; 32(6): 502-517, 2018 Nov.
Artigo em Inglês | MEDLINE | ID: mdl-30253652

RESUMO

OBJECTIVES: Our intention was to review all material published to date regarding superantigens (SAgs) and allergy from an otorhinolaryngological viewpoint to understand this association more clearly. METHODS: We identified all materials published mentioning both SAg and allergic rhinitis (AR), chronic sinusitis, asthma, and atopic dermatitis (AD) that are indexed on PubMed, Google, or the ProQuest Central databases. RESULTS: Staphylococcus aureus is a significant bacterial pathogen in humans and has the ability to produce enterotoxins with superantigenic features. The inflammatory response in allergy seen in both B cell and T cell may be attributed to SAgs. Sufferers of both allergic asthma with rhinitis and AR alone produce serological evidence of immunoglobulin E formation to SAgs produced by S. aureus. Perennial AR sufferers carry S. aureus more frequently and the presence of the organism within the nasal cavity may exacerbate perennial AR. SAg produced by S. aureus potentially worsens the asthmatic inflammatory response within the airway and may lead to the airways becoming hyperresponsive, as well as possibly activating T cells if asthmatic control is poor. Staphylococcal SAgs potentially increase the risk of developing chronic rhinosinusitis with nasal polyposis, additionally being a marker for more severe disease. If SAgs bring about chronic inflammatory responses in the nose and sinuses, then T cells excreting interferon-gamma may be a crucial mediator. In allergic dermatitis, S. aureus could be a key player in exacerbation of the condition. Even in younger pediatric patients with allergic dermatitis, allergic hypersensitivity to SAgs is frequent and may be a factor explaining how severe the condition becomes. CONCLUSION: Just as SAgs are known to feature in many allergic conditions, they play their part in AR, chronic rhinosinusitis, asthma, and AD. Further research is required before the relationship between SAgs and allergy can be adequately explained.


Assuntos
Asma/imunologia , Dermatite Atópica/imunologia , Inflamação/imunologia , Rinite Alérgica/imunologia , Sinusite/imunologia , Infecções Estafilocócicas/imunologia , Staphylococcus aureus/imunologia , Alérgenos/imunologia , Animais , Antígenos de Bactérias/imunologia , Humanos , Imunidade Celular , Interferon gama/metabolismo , Superantígenos/imunologia
20.
Infect Immun ; 86(11)2018 11.
Artigo em Inglês | MEDLINE | ID: mdl-30201699

RESUMO

Superantigens (SAgs) represent a diverse family of bacterial toxins that induce Vß-specific T cell proliferation associated with an array of important diseases in humans and animals, including mastitis of dairy cows. However, an understanding of the diversity and distribution of SAg genes among bovine Staphylococcus aureus strains and their role in the pathogenesis of mastitis is lacking. Population genomic analysis of 195 bovine S. aureus isolates representing 57 unique sequence types revealed that strains encode 2 to 13 distinct SAgs and that the majority of isolates contain 5 or more SAg genes. A genome-scale analysis of bovine reference strain RF122 revealed a complement of 11 predicted SAg genes, which were all expressed in vitro Detection of specific antibodies in convalescent cows suggests expression of 7 of 11 SAgs during natural S. aureus infection. We determined the Vß T cell activation profile for all functional SAgs encoded by RF122, revealing evidence for bovine host-specific activity among the recently identified RF122-encoded SAgs SElY and SElZ. Remarkably, we discovered that some strains have evolved the capacity to stimulate the entire T cell repertoire of cattle through an array of diverse SAgs, suggesting a key role in bovine immune evasion.


Assuntos
Antígenos de Bactérias/imunologia , Ativação Linfocitária , Staphylococcus aureus/imunologia , Superantígenos/imunologia , Linfócitos T/imunologia , Animais , Bovinos , Proliferação de Células , Evasão da Resposta Imune , Mastite Bovina/patologia , Infecções Estafilocócicas/patologia , Infecções Estafilocócicas/veterinária
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