Human milk composition differs in healthy mothers and mothers with celiac disease.

PURPOSE: To investigate whether breast-milk composition and microbiota differ in healthy mothers and mothers with celiac disease (CD) to ultimately contribute to identify additional factors determining CD risk. METHODS: Breast-milk samples from healthy mothers (n = 12) and mothers with CD (n = 12) were collected. Cytokines and secretory immunoglobulin A (sIgA) were analyzed by bead-arrays and flow cytometry and human milk oligosaccharides (HMOs) were assessed by capillary electrophoresis with laser-induced fluorescence (CE-LIF) detection. Breast-milk microbiota composition was analyzed by conventional and quantitative real-time PCR. RESULT: Breast milk from CD mothers showed significantly lower levels of interleukin (IL) 12p70 (P < 0.042), transforming growth factor (TGF)-ß1 (P < 0.018) and sIgA (P < 0.003) and almost significantly lower levels of interferon (IFN)-γ (P < 0.058). Six mothers in each group belonged to the secretor Le(a-b+) type, one to the secretor Le(a-b-) type and five to the non-secretor Le(a+b-) type. CD mothers of non-secretor Le(a+b-) type showed increased Lacto-N-tetraose content (P < 0.042) compared with healthy mothers. CD mothers' milk showed reduced gene copy numbers of Bifidobacterium spp. (P < 0.026) and B. fragilis group (P < 0.044). CONCLUSION: CD mothers' breast milk is characterized by a reduced abundance of immunoprotective compounds (TGF-ß1 and sIgA) and bifidobacteria. The reduction in these components could theoretically diminish the protective effects of breast-feeding on the child's future risk of developing CD.

RinA controls phage-mediated packaging and transfer of virulence genes in Gram-positive bacteria.

Phage-mediated transfer of microbial genetic elements plays a crucial role in bacterial life style and evolution. In this study, we identify the RinA family of phage-encoded proteins as activators required for transcription of the late operon in a large group of temperate staphylococcal phages. RinA binds to a tightly regulated promoter region, situated upstream of the terS gene, that controls expression of the morphogenetic and lysis modules of the phage, activating their transcription. As expected, rinA deletion eliminated formation of functional phage particles and significantly decreased the transfer of phage and pathogenicity island encoded virulence factors. A genetic analysis of the late promoter region showed that a fragment of 272 bp contains both the promoter and the region necessary for activation by RinA. In addition, we demonstrated that RinA is the only phage-encoded protein required for the activation of this promoter region. This region was shown to be divergent among different phages. Consequently, phages with divergent promoter regions carried allelic variants of the RinA protein, which specifically recognize its own promoter sequence. Finally, most Gram-postive bacteria carry bacteriophages encoding RinA homologue proteins. Characterization of several of these proteins demonstrated that control by RinA of the phage-mediated packaging and transfer of virulence factor is a conserved mechanism regulating horizontal gene transfer.

Immune development and intestinal microbiota in celiac disease.

Celiac disease (CD) is an immune-mediated enteropathy, triggered by dietary wheat gluten and similar proteins of barley and rye in genetically susceptible individuals. The etiology of this disorder is complex, involving both environmental and genetic factors. The major genetic risk factor for CD is represented by HLA-DQ genes, which account for approximately 40% of the genetic risk; however, only a small percentage of carriers develop the disease. Gluten is the main environmental factor responsible for the signs and symptoms of the disease, but exposure to gluten does not fully explain the manifestation of CD. Epidemiological and clinical data suggest that environmental factors other than gluten might play a role in disease development, including early feeding practices (e.g., breast milk versus formula and duration of breastfeeding), infections, and alterations in the intestinal microbiota composition. Herein, we review what is known about the influence of dietary factors, exposure to infectious agents, and intestinal microbiota composition, particularly in early life, on the risk of developing CD, as well as the possible dietary strategies to induce or increase gluten tolerance.

Staphylococcus aureus pathogenicity island DNA is packaged in particles composed of phage proteins.

Staphylococcus aureus pathogenicity islands (SaPIs) have an intimate relationship with temperate staphylococcal phages. During phage growth, SaPIs are induced to replicate and are efficiently encapsidated into special small phage heads commensurate with their size. We have analyzed by amino acid sequencing and mass spectrometry the protein composition of the specific SaPI particles. This has enabled identification of major capsid and tail proteins and a putative portal protein. As expected, all these proteins were phage encoded. Additionally, these analyses suggested the existence of a protein required for the formation of functional phage but not SaPI particles. Mutational analysis demonstrated that the phage proteins identified were involved only in the formation and possibly the function of SaPI or phage particles, having no role in other SaPI or phage functions.

Role of staphylococcal phage and SaPI integrase in intra- and interspecies SaPI transfer.

SaPIbov2 is a member of the SaPI family of staphylococcal pathogenicity islands and is very closely related to SaPIbov1. Typically, certain temperate phages can induce excision and replication of one or more of these islands and can package them into special small phage-like particles commensurate with their genome sizes (referred to as the excision-replication-packaging [ERP] cycle). We have studied the phage-SaPI interaction in some depth using SaPIbov2, with special reference to the role of its integrase. We demonstrate here that SaPIbov2 can be induced to replicate by different staphylococcal phages. After replication, SaPIbov2 is efficiently encapsidated and transferred to recipient organisms, including different non-Staphylococcus aureus staphylococci, where it integrates at a SaPI-specific attachment site, att(C), by means of a self-coded integrase (Int). Phages that cannot induce the SaPIbov2 ERP cycle can transfer the island by recA-dependent classical generalized transduction and can also transfer it by a novel mechanism that requires the expression of SaPIbov2 int in the recipient but not in the donor. It is suggested that this mechanism involves the encapsidation of standard transducing fragments containing the intact island followed by int-mediated excision, circularization, and integration in the recipient.