The virulence profiles of most atypical enteropathogenic Escherichia coli (EPEC) strains are unknown. A total of 118 typical and atypical strains of EPEC serotypes and non-EPEC serogroups isolated from children with or without acute diarrhea who were from different cities in Brazil were examined for virulence-associated markers and adherence to HEp-2 cells, and also had random amplified polymorphic DNA (RAPD) analysis performed. Atypical strains were identical to typical strains with regard to the virulence factors encoded on the locus of enterocyte effacement (LEE). In contrast with typical EPEC strains, none of the atypical strains reacted with the bfpA probe, and half of the strains hybridized with the perA probe. Most atypical strains presented Tir sequences that correlated with enteropathogenic or enterohemorrhagic E. coli (98%), had LEE inserted in either selC or pheU (88%), and presented a typeable intimin (52%). Eighteen new serotypes were found in the EPEC strains. Atypical and typical EPEC strains belonged to different RAPD clusters. Most atypical strains showed a localized-like adherence pattern (61.5%). Of the non-LEE-encoded virulence factors, enteroaggregative E. coli heat-stable enterotoxin was noted most frequently (45%) and was significantly associated with diarrhea (P=.01). Thus, this virulence marker may be used as an additional tool for the diagnosis of truly atypical pathogenic strains.

No abstract

We previously described – studying transcriptional signatures of hippocampal CA3 explants – that febrile (FS) and afebrile (NFS) forms of refractory mesial temporal lobe epilepsy constitute two distinct genomic phenotypes. That network analysis was based on a limited number (hundreds) of differentially expressed genes (DE networks) among a large set of valid transcripts (close to two tens of thousands). Here we developed a methodology for complex network visualization (3D) and analysis that allows the categorization of network nodes according to distinct hierarchical levels of gene-gene connections (node degree) and of interconnection between node neighbors (concentric node degree). Hubs are highly connected nodes, VIPs have low node degree but connect only with hubs, and high-hubs have VIP status and high overall number of connections. Studying the whole set of CA3 valid transcripts we: i) obtained complete transcriptional networks (CO) for FS and NFS phenotypic groups; ii) examined how CO and DE networks are related; iii) characterized genomic and molecular mechanisms underlying FS and NFS phenotypes, identifying potential novel targets for therapeutic interventions. We found that: i) DE hubs and VIPs are evenly distributed inside the CO networks; ii) most DE hubs and VIPs are related to synaptic transmission and neuronal excitability whereas most CO hubs, VIPs and high hubs are related to neuronal differentiation, homeostasis and neuroprotection, indicating compensatory mechanisms. Complex network visualization and analysis is a useful tool for systems biology approaches to multifactorial diseases. Network centrality observed for hubs, VIPs and high hubs of CO networks, is consistent with the network disease model, where a group of nodes whose perturbation leads to a disease phenotype occupies a central position in the network. Conceivably, the chance for exerting therapeutic effects through the modulation of particular genes will be higher if these genes are highly interconnected in transcriptional networks.

Objective: To evaluate the frequency of primary immunodeficiencies (PID) in juvenile systemic lupus erythematosus (JSLE) patients. Methods: Some 72 JSLE patients were analyzed for levels of immunoglobulin classes and IgG subclasses and early components of the classical complement pathway. Determination of C4 gene copy number (GCN) and detection of type I C2 deficiency (D) were also performed. Results: PID was identified in 16 patients (22%): C2D in three, C4D in three, C1qD in two, IgG2D (<20 mg/dl) in four, IgAD (<7 mg/dl) in three, and IgMD (<35 mg/dl) in three; one of these patients presented IgA, C2 and C4D. Two patients had low C4 GCN and two had type I C2D. Demographic data, family history of autoimmune disease and PID, JSLE clinical findings, occurrence of infections, disease activity and therapies were similar in patients with and without PID (p > 0.05). Remarkably, the median of Systemic Lupus International Collaborating Clinics/ACR-damage index (SLICC/ ACR-DI) was significantly higher in JSLE patients with PID compared with patients without these abnormalities (p ¼ 0.0033), likewise the high frequency of SLICC/ACR-DI > 1 (p ¼ 0.023). Conclusions: A high frequency of PID was observed in JSLE patients, suggesting that these defects may contribute to lupus development. Our findings indicate that these two groups of PID should be investigated in severe pediatric lupus. Lupus (2011) 20, 1275-1284.

BackgroundProlonged febrile seizures constitute an initial precipitating injury (IPI) commonly associated with refractory mesial temporal lobe epilepsy (RMTLE). In order to investigate IPI influence on the transcriptional phenotype underlying RMTLE we comparatively analyzed the transcriptomic signatures of CA3 explants surgically obtained from RMTLE patients with (FS) or without (NFS) febrile seizure history. Texture analyses on MRI images of dentate gyrus were conducted in a subset of surgically removed sclerotic hippocampi for identifying IPI-associated histo-radiological alterations.Methodology/Principal FindingsDNA microarray analysis revealed that CA3 global gene expression differed significantly between FS and NFS subgroups. An integrative functional genomics methodology was used for characterizing the relations between GO biological processes themes and constructing transcriptional interaction networks defining the FS and NFS transcriptomic signatures and its major gene-gene links (hubs). Co-expression network analysis showed that: i) CA3 transcriptomic profiles differ according to the IPI; ii) FS distinctive hubs are mostly linked to glutamatergic signalization while NFS hubs predominantly involve GABAergic pathways and neurotransmission modulation. Both networks have relevant hubs related to nervous system development, what is consistent with cell genesis activity in the hippocampus of RMTLE patients. Moreover, two candidate genes for therapeutic targeting came out from this analysis: SSTR1, a relevant common hub in febrile and afebrile transcriptomes, and CHRM3, due to its putative role in epilepsy susceptibility development. MRI texture analysis allowed an overall accuracy of 90% for pixels correctly classified as belonging to FS or NFS groups. Histological examination revealed that granule cell loss was significantly higher in FS hippocampi.Conclusions/SignificanceCA3 transcriptional signatures and dentate gyrus morphology fairly correlate with IPI in RMTLE, indicating that FS-RMTLE represents a distinct phenotype. These findings may shed light on the molecular mechanisms underlying refractory epilepsy phenotypes and contribute to the discovery of novel specific drug targets for therapeutic interventions.

SummaryDiarrhoeagenic Escherichia coli strains of serotype O111:H12 are characterized by their aggregative pattern of adherence on cultured epithelial cells and thus are considered enteroaggregative E. coli (EAEC). We have previously shown that these EAEC strains lack the genes encoding the aggregative fimbriae I and II described in other heterologous EAEC strains. In this paper, we show compelling data suggesting that a plasmid-encoded outer membrane 58 kDa protein termed aggregative protein 58 (Ap58) produced by EAEC O111:H12 strains, is associated with the adherence capabilities and haemagglutination of animal red blood cells. This conclusion is supported by several lines of evidence: (i) adherent O111:H12 strains are able to produce Ap58; (ii) non-adherent O111:H12 strains are unable to produce Ap58; (iii) antibodies raised against Ap58 inhibited adherence and haemagglutination of epithelial and bovine red blood cells, respectively; (iv) a non-adherent E. coli K-12 host strain containing the ap58 gene determinant on plasmid pVM15 displayed abundant adherence to cultured HEp-2 cells; and (v) the purified Ap58 bound specifically to HEp-2 and bovine red blood cells. Our findings indicate that the aggregative adherence in the O111:H12 strains may be also mediated by nonfimbrial adhesins. We believe our data contribute to the understanding of the adherence mechanisms of these organisms.

Atypical enteropathogenic Escherichia coli (aEPEC) has been associated with infantile diarrhea in many countries. The clonal structure of aEPEC is the object of active investigation but few works have dealt with its genetic relationship with other diarrheagenic E. coli (DEC). This study aimed to evaluate the genetic relationship of aEPEC with other DEC pathotypes. The phylogenetic relationships of DEC strains were evaluated by multilocus sequence typing. Genetic diversity was assessed by pulsed-field gel electrophoresis (PFGE). The phylogram showed that aEPEC strains were distributed in four major phylogenetic groups (A, B1, B2 and D). Cluster I (group B1) contains the majority of the strains and other pathotypes [enteroaggregative, enterotoxigenic and enterohemorrhagic E. coli (EHEC)]; cluster II (group A) also contains enteroaggregative and diffusely adherent E. coli; cluster III (group B2) has atypical and typical EPEC possessing H6 or H34 antigen; and cluster IV (group D) contains aEPEC O55:H7 strains and EHEC O157:H7 strains. PFGE analysis confirmed that these strains encompass a great genetic diversity. These results indicate that aEPEC clonal groups have a particular genomic background--especially the strains of phylogenetic group B1--that probably made possible the acquisition and expression of virulence factors derived from non-EPEC pathotypes.

No abstract