Accelerated induction of experimental allergic encephalomyelitis in PL/J mice by a non-V beta 8-specific superantigen.

Superantigens such as the staphylococcal enterotoxins can play an important role in exacerbation of autoimmune disorders such as experimental allergic encephalomyelitis (EAE) in mice. In fact, superantigens can reactivate EAE in PL/J mice that have been sensitized to rat myelin basic protein (MBP). The T-cell subset predominantly responsible for disease in PL/J mice bears the V beta 8+ T-cell antigen receptor (TCR). The question arises as to whether T cells bearing other V beta specificities are involved in induction or reactivation of EAE with superantigen. Thus, we have investigated the ability of a non-V beta 8-specific superantigen, staphylococcal enterotoxin A (SEA) (V beta specificities 1, 3, 10, 11, and 17), to induce EAE in PL/J mice that have been previously protected from disease by anergy and deletion of V beta 8+ T cells. PL/J mice were first pretreated with the V beta 8-specific superantigen staphylococcal enterotoxin B (SEB) and then immunized with MBP. These mice exhibited V beta 8-specific anergy and depletion and did not develop EAE, even when further treated with SEB. However, administration of SEA to these same mice induced an initial episode of EAE which was characterized by severe hindleg paralysis and accelerated onset of disease. In contrast to SEB pretreatment, PL/J mice pretreated with SEA did develop EAE when immunized with MBP, and after resolution of clinical signs of disease these mice were susceptible to relapse of EAE induced by SEB but not by SEA. Thus, superantigens can activate encephalitogenic MBP-specific non-V beta 8+ T cells to cause EAE in PL/J mice. These data suggest that superantigens can play a central role in autoimmune disorders and that they introduce a profound complexity to autoimmune diseases such as EAE, akin to the complexity seen in multiple sclerosis.

Avaliação fenotípica e funcional de células dendríticas inflamatórias na dermatite atópica do adulto

Introdução: A dermatite atópica (DA) é uma enfermidade cutânea inflamatória de caráter crônico, na qual o prurido é constante, e com marcada xerose. Dermatose que geralmente se inicia na infância, e pode surgir em indivíduos com história pessoal ou familiar de asma, rinite alérgica e/ou DA. A pele com DA apresenta colonização por Staphylococcus aureus (S. aureus) em 80-100% dos casos, sendo responsável pela produção enterotoxinas, capazes de exacerbar a resposta inflamatória na DA. Nesta enfermidade, existem distintos subtipos de células apresentadoras de antígeno ou dendríticas (DC), tanto na pele quanto circulantes. As DC exercem papel relevante na inflamação da DA, em especial um subgrupo de células dendríticas mieloides (mDC), as chamadas células dendríticas inflamatórias epidérmicas (IDEC). Objetivo: Avaliar o fenótipo e a função das mDC (IDEC-like) em células mononucleares do sangue periférico (PBMC) na DA do adulto. Métodos: Foram selecionados 21 pacientes com DA (idades entre18 e 65 anos, sendo 13 homens e oito mulheres) e 21 controles (idades entre 21 e 41 anos, sendo oito homens e 13 mulheres), nos quais foram realizadas as avaliações fenotípica e funcional das mDC (IDEC-like) em PBMC. Para tal, foram analisadas as expressões de: Fc?RI, TNF, IFN-y, IL-10, CD36 e CD83 nas mDC, estimuladas com enterotoxina estafilocócica B (SEB), agonistas de TLR2 (Pam3CSK4), TLR4 (LPS) e de TLR7/8 (CL097) através da citometria de fluxo. Resultados: Os principais achados nos pacientes com DA foram: aumento da frequência de células IDEC-like frente ao estímulo com agonista de TLR2 (Pam3CSK4); aumento da frequência de IFN-y em condição não estimulada, e de IL-10 frente a estímulo com agonista de TLR7/8 (CL097) nesta população de células dendríticas. Conclusão: A caracterização das mDC circulantes na DA evidencia perfil pró-inflamatório em condição não estimulada, impactando na resposta imune adaptativa. O aumento significativo na frequência de células IDEC-like nos pacientes com DA sugere sua participação na perpetuação do processo inflamatório da DA

Pathotypes and serogroups of enterotoxigenic Escherichia coli isolated from pre-weaning pigs in north Vietnam

The contribution of enterotoxigenic Escherichia coli (ETEC) to pre-weaning diarrhoea was investigated over a 6 month period at five selected commercial piggeries (CPs) in north Vietnam with at least 100 sows each. Diarrhoea was found to affect 71(.)5% of the litters born during the period of study. Of 406 faecal specimens submitted for bacteriological culture, 200 (49(.)3%) yielded a heavy pure culture of E coli and 126(31 %)were confirmed by PCR to carry at least one of eight porcine ETEC virulence genes. ETEC was responsible for 43% of cases of diarrhoea in neonatal pigs during the first 4 days of life and 23(.)9% of the remaining cases up until the age of weaning. Pathotypes were determined by PCR for the 126 ETEC isolates together with 44 ETEC isolates obtained from village pigs (VPs) raised by smallholder farmers. The CP isolates belonged to five pathotypes, four of which were also identified in VP isolates. Haemolytic serogroup O149: K91 isolates that belonged to F4/STa/STb/LT were most commonly identified in both CPs (33 % of isolates) and VPs (45(.)5%). Other combinations identified in both production systems included O64 (F5/STa), O101 (F4/STa/STb) and O-nontypable (F-/STb). A high proportion of CP isolates (22(.)3 %) possessed all three enterotoxins (STa/STWLT), lacked the genes for all five tested fimbriae (F4, F5, F6, F41 and F18) and belonged to serogroup O8. These unusual 08 F- isolates were haemolytic and were isolated from all ages of diarrhoeic piglets at each CP, suggesting that they have pathogenic potential.

Relationship between super antigenicity, antimicrobial resistance and origin of Staphylococcus aureus isolated

Introduction: Staphylococcus aureus is a pathogen that causes food poisoning as well as hospital and community acquired infections. Objective: Establish the profile of superantigen genes among hospital isolates in relation to clinical specimen type, susceptibility to antibiotics and hospital or community acquisition. Methods: Eighty one isolates obtained from patients at Colombian hospital, were classified by antimicrobial susceptibility, specimen type and hospital or community acquired . The PCR uniplex and multiplex was used for detection of 22 superantigen genes (18 enterotoxins, tsst-1 and three exfoliative toxins). Results: Ninety five point one percent of isolates harbored one or more of the genes with an average of 5.6 genes. Prevalence of individual genes was variable and the most prevalent was seg (51.9%). Thirty nine genotypes were obtained, and the genotype gimnou (complete egc cluster) was the most prevalent alone (16.0%) and in association with other genes (13.6%). The correlation between presence of superantigens and clinical specimen or antimicrobial susceptibility showed no significant difference. But there was significant difference between presence of superantigens and the origin of the isolates, hospital or community acquired (p= 0.049). Conclusions: The results show the variability of the superantigen genes profile in hospital isolates and shows no conclusive relationship with the clinical sample type and antimicrobial susceptibility, but there was correlation with community and hospital isolates. The analysis of the interplay between virulence, epidemic and antibiotic resistance of bacterial populations is needed to predict the future of infectious diseases.