A multimeric protein that behaves functionally as an authentic ferritin has been isolated from the Gram-positive bacterium Listeria innocua. The purified protein has a molecular mass of about 240,000 Da and is composed of a single type of subunit (18,000 Da). L. innocua ferritin is able to oxidize and sequester about 500 iron atoms inside the protein cage. The primary structure reveals a high similarity to the DNA-binding proteins designated Dps. Among the proven ferritins, the most similar sequences are those of mammalian L chains that appear to share with L. innocua ferritin the negatively charged amino acids corresponding to the iron nucleation site. In L. innocua ferritin, an additional aspartyl residue may provide a strong complexing capacity that renders the iron oxidation and incorporation processes extremely efficient. This study provides the first experimental evidence for the existence of a non-heme bacterial ferritin that is related to Dps proteins, a finding that lends support to the recent suggestion of a common evolutionary origin of these two protein families.

BackgroundCeliac Disease (CD) is an autoimmune disorder of the small intestine in which dietary gluten ingestion leads to a chronic enteropathy. Recently, scientific evidence suggested a potential role of gut microbiota in CD. To have a snapshot of dominant duodenal microbiota we analyzed the mucosa-associated microbiota of 20 children with CD, before and after a gluten-free diet (GFD) regimen, and of 10 controls. Total DNA was extracted from duodenal biopsies and amplification products of 16S ribosomal DNA were compared by temporal temperature gradient gel electrophoresis (TTGE). TTGE profiles were analyzed by statistical multivariate analysis.ResultsThe average number of bands in TTGE profiles was significantly higher (P < 0.0001) in active (n.b. 16.7 ± 0.7) and inactive states (n.b. 13.2 ± 0.8) than in controls (n.b. 3.7 ± 1.3). Mean interindividual similarity index was 54.9% ± 14.9% for active disease, 55.6% ± 15.7% for remission state and 21.8% ± 30.16% for controls. Similarity index between celiac children before and after GFD treatment was 63.9% ± 15.8%. Differences in microbiota biodiversity were among active and remission state (P = 0.000224) and amid active CD and controls (P < 0.001). Bacteroides vulgatus and Escherichia coli were detected more often in CD patients than in controls (P < 0.0001).ConclusionsOverall, the results highlighted a peculiar microbial TTGE profile and a significant higher biodiversity in CD pediatric patients' duodenal mucosa. The possible pathophysiological role of these microbial differences needs further characterization.

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BackgroundAdherent-invasive Escherichia coli (AIEC) have been implicated in the ethiopathogenesis of Crohn’s disease (CD). In this study, we analyzed a collection of intestinal mucosa-associated E. coli isolates, presenting AIEC phenotypes, isolated from biopsies of CD pediatric patients and non-inflammatory bowel diseases (IBD) controls, in order to investigate their genetic and phenotypic pathogenic features.ResultsA total of 616 E. coli isolates from biopsies of four pediatric CD patients and of four non-IBD controls were collected and individually analyzed. For AIEC identification, adherent isolates were assayed for invasiveness, and the capacity of the adhesive-invasive isolates to survive and replicate intracellularly was determined over macrophages J774. In this way we identified 36 AIEC-like isolates. Interestingly, their relative abundance was significantly higher in CD patients (10%; 31/308) than in non-IBD controls (1%; 5/308) (χ2 = 38.96 p < 0.001). Furthermore pulsed field gel electrophoresis (PFGE) and randomly amplified polymorphic DNA (RAPD) techniques were applied to analyze the clonality of the 36 AIEC-like isolates. The results obtained allowed us to identify 27 distinct genotypes (22 from CD patients and 5 from non-IBD controls). As for the AIEC prototype strain LF82, all 27 AIEC genotypes presented an aggregative pattern of adherence (AA) that was inhibited by D-mannose, indicating that adhesiveness of AIEC is likely mediated by type 1 pili. PCR analisys was used to investigate presence of virulence genes. The results indicated that among the 27 AIEC isolates, the incidence of genes encoding virulence factors K1 (χ2 = 6.167 P = 0.013), kpsMT II (χ2 = 6.167 P = 0.013), fyuA (χ2 = 6.167 P = 0.013), and ibeA (χ2 = 8.867 P = 0.003) was significantly higher among AIEC strains isolated from CD patients than non-IBD controls.ConclusionsThe identification of AIEC strains in both CD and non-IBD controls, confirmed the “pathobiont” nature of AIEC strains. The finding that AIEC-like isolates were more abundant in CD patients, indicates that a close association of these strains with CD may also exists in pediatric patients.

Conflicting data are reported on pro- or anti-inflammatory activity of bovine lactoferrin (bLf) in different cell models as phagocytes or epithelial cell lines infected by bacteria. Here we evaluated the bLf effect on epithelial models mimicking two human pathologies characterized by inflammation and infection with specific bacterial species. Primary bronchial epithelium from a cystic fibrosis (CF) patient and differentiated intestinal epithelial cells were infected with Pseudomonas aeruginosa LESB58 isolated from a CF patient and Adherent-Invasive Escherichia coli LF82 isolated from a Crohn's disease patient. Surprisingly, bLf significantly reduced the intracellular bacterial survival, but differently modulated the inflammatory response. These data lead us to hypothesize that bLf differentially acts depending on the epithelial model and infecting pathogen. To verify this hypothesis, we explored whether bLf could modulate ferroportin (Fpn), the only known cellular iron exporter from cells, that, by lowering the intracellular iron level, determines a non permissive environment for intracellular pathogens. Here, for the first time, we describe the bLf ability to up-regulate Fpn protein in infected epithelial models. Our data suggest that the mechanism underlying the bLf modulating activity on inflammatory response in epithelial cells is complex and the bLf involvement in modulating cellular iron homeostasis should be taken into account.