The lacdiNAc-specific adhesin LabA mediates adhesion of Helicobacter pylori to human gastric mucosa

Adhesion of Helicobacter pylori to the gastric mucosa is a necessary prerequisite for the pathogenesis of H. pylori-related diseases. In this study, we investigated the GalNAcβ1-4GlcNAc motif (also known as N,N'-diacetyllactosediamine [lacdiNAc]) carried by MUC5AC gastric mucins as the target for bacterial binding to the human gastric mucosa. The expression of LacdiNAc carried by gastric mucins was correlated with H. pylori localization, and all strains tested adhered significantly to this motif. Proteomic analysis and mutant construction allowed the identification of a yet uncharacterized bacterial adhesin, LabA, which specifically recognizes lacdiNAc. These findings unravel a target of adhesion for H. pylori in addition to moieties recognized by the well-characterized adhesins BabA and SabA. Localization of the LabA target, restricted to the gastric mucosa, suggests a plausible explanation for the tissue tropism of these bacteria. These results pave the way for the development of alternative strategies against H. pylori infection, using adherence inhibitors.

Interleukin-22 reduces lung inflammation during influenza A virus infection and protects against secondary bacterial infection

Interleukin-22 (IL-22) has redundant, protective, or pathogenic functions during autoimmune, inflammatory, and infectious diseases. Here, we addressed the potential role of IL-22 in host defense and pathogenesis during lethal and sublethal respiratory H3N2 influenza A virus (IAV) infection. We show that IL-22, as well as factors associated with its production, are expressed in the lung tissue during the early phases of IAV infection. Our data indicate that retinoic acid receptor-related orphan receptor-γt (RORγt)-positive αβ and γδ T cells, as well as innate lymphoid cells, expressed enhanced Il22 transcripts as early as 2 days postinfection. During lethal or sublethal IAV infections, endogenous IL-22 played no role in the control of IAV replication and in the development of the IAV-specific CD8(+) T cell response. During lethal infection, where wild-type (WT) mice succumbed to severe pneumonia, the lack of IL-22 did not accelerate or delay IAV-associated pathogenesis and animal death. In stark contrast, during sublethal IAV infection, IL-22-deficient animals had enhanced lung injuries and showed a lower airway epithelial integrity relative to WT littermates. Of importance, the protective effect of endogenous IL-22 in pulmonary damages was associated with a more controlled secondary bacterial infection. Indeed, after challenge with Streptococcus pneumoniae, IAV-experienced Il22(-/-) animals were more susceptible than WT controls in terms of survival rate and bacterial burden in the lungs. Together, IL-22 plays no major role during lethal influenza but is beneficial during sublethal H3N2 IAV infection, where it limits lung inflammation and subsequent bacterial superinfections.

[Cutaneous polymorph manifestations of familial Mediterranean fever in a child]

We describe the case of a 4-year-old child with Mediterranean fever characterized by cutaneous features. Familial Mediterranean fever is an autosomal recessive disorder characterized by recurrent attacks of fever and polyserositis including peritonitis, pleuritis, and arthritis. Skin involvement is less common. In our case, the successively patient presented erysipelas-like erythema, edemas of the palmar and plantar regions, and purpuric lesions. From these clinical observations, several diagnoses were raised: infectious erysipelas, Kawasaki disease, Henoch-Schönlein purpura, and familial Mediterranean fever. Only the latter diagnosis was confirmed after exploration and then confirmed with genetic analysis, which found a M694V homozygous mutation. Erysipelas-like erythema is the most frequent cutaneous sign reported in the literature and the only one to be associated with the M694V homozygous mutation. The originality of this case is the dominancy and polymorphism of the skin lesions.

Bisphenol A stimulates human prostate cancer cell migration via remodelling of calcium signalling

Bisphenol A (BPA), the principal constituent of reusable water bottles, metal cans, and plastic food containers, has been shown to be involved in human prostate cancer (PCa) cell proliferation. The aim of the present study was to explore the effect of BPA on PCa cell migration and the pathways involved in these processes. Using the transwell technique, we clearly show for the first time that the pre-treatment of the cells with BPA (1–10 nM) induces human PCa cell migration. Using a calcium imaging technique, we show that BPA pre-treatment induces an amplification of Store-Operated Calcium Entry (SOCE) in LNCaP cells. RT-PCR and Western blot experiments allowed the identification of the ion channel proteins which are up-regulated by BPA pre-treatments. These include the Orai1 protein, which is known as an important SOCE actor in various cell systems, including human PCa cells. Using a siRNA strategy, we observed that BPA-induced amplification of SOCE was Orai1-dependent. Interestingly, the BPA-induced PCa cell migration was suppressed when the calcium entry was impaired by the use of SOCE inhibitors (SKF96365, BTP2), or when the extracellular calcium was chelated. Taken together, the results presented here show that BPA induces PCa cells migration via a modulation of the ion channel protein expression involved in calcium entry and in cancer cell migration. The present data provide novel insights into the molecular mechanisms involved in the effects of an environmental factor on cancer cells and suggest both the necessity of preventive measures and the possibility of targeting ion channels in the treatment of PCa cell metastasis.

Cryptosporidium parvum infection in SCID mice infected with only one oocyst: qPCR assessment of parasite replication in tissues and development of digestive cancer

Dexamethasone (Dex) treated Severe Combined Immunodeficiency (SCID) mice were previously described as developing digestive adenocarcinoma after massive infection with Cryptosporidium parvum as soon as 45 days post-infection (P.I.). We aimed to determine the minimum number of oocysts capable of inducing infection and thereby gastrointestinal tumors in this model. Mice were challenged with calibrated oocyst suspensions containing intended doses of: 1, 10, 100 or 10⁵ oocysts of C. parvum Iowa strain. All administered doses were infective for animals but increasing the oocyst challenge lead to an increase in mice infectivity (P = 0.01). Oocyst shedding was detected at 7 days P.I. after inoculation with more than 10 oocysts, and after 15 days in mice challenged with one oocyst. In groups challenged with lower inocula, parasite growth phase was significantly higher (P = 0.005) compared to mice inoculated with higher doses. After 45 days P.I. all groups of mice had a mean of oocyst shedding superior to 10,000 oocyst/g of feces. The most impressive observation of this study was the demonstration that C. parvum-induced digestive adenocarcinoma could be caused by infection with low doses of Cryptosporidium, even with only one oocyst: in mice inoculated with low doses, neoplastic lesions were detected as early as 45 days P.I. both in the stomach and ileo-caecal region, and these lesions could evolve in an invasive adenocarcinoma. These findings show a great amplification effect of parasites in mouse tissues after challenge with low doses as confirmed by quantitative PCR. The ability of C. parvum to infect mice with one oocyst and to develop digestive adenocarcinoma suggests that other mammalian species including humans could be also susceptible to this process, especially when they are severely immunocompromised.

[Preimplantation genetic diagnosis--developments to expect?]

Preimplantation genetic diagnosis (PGD) has been practiced for over 20 years. It prevents the birth of children with serious genetic diseases by selecting healthy embryos before pregnancy. In France, the initial indications of PGD have been extended in two directions: on the one hand, to allow identification of a mutation combined with embryo's HLA typing, to obtain, at birth, stem cells for therapeutic purposes, and on the other hand, to avoid transmission of late onset diseases without having to test the at-risk parent. Other applications are practiced worldwide but are not allowed in our country, such as social sexing. Technological developments can enable more complex diagnosis, research of several diseases or other genetic traits. It may be useful, for example, to use this possibility to add screening for Down's syndrome at any PDG in older women, when the risk is high. Other objectives were considered but presenting difficulties in their application, not only for regulatory and technical reasons, but also from an ethical point of view.

Interleukin-22 is produced by invariant natural killer T lymphocytes during influenza A virus infection: potential role in protection against lung epithelial damages

Invariant natural killer T (iNKT) cells are non-conventional lipid-reactive αβ T lymphocytes that play a key role in host responses during viral infections, in particular through the swift production of cytokines. Their beneficial role during experimental influenza A virus (IAV) infection has recently been proposed, although the mechanisms involved remain elusive. Here we show that during in vivo IAV infection, mouse pulmonary iNKT cells produce IFN-γ and IL-22, a Th17-related cytokine critical in mucosal immunity. Although permissive to viral replication, IL-22 production by iNKT cells is not due to IAV infection per se of these cells but is indirectly mediated by IAV-infected dendritic cells (DCs). We show that activation of the viral RNA sensors TLR7 and RIG-I in DCs is important for triggering IL-22 secretion by iNKT cells, whereas the NOD-like receptors NOD2 and NLRP3 are dispensable. Invariant NKT cells respond to IL-1β and IL-23 provided by infected DCs independently of the CD1d molecule to release IL-22. In vitro, IL-22 protects IAV-infected airway epithelial cells against mortality but has no role on viral replication. Finally, during early IAV infection, IL-22 plays a positive role in the control of lung epithelial damages. Overall, IAV infection of DCs activates iNKT cells, providing a rapid source of IL-22 that might be beneficial to preserve the lung epithelium integrity.

Polycyclic aromatic hydrocarbons within airborne particulate matter (PM(2.5)) produced DNA bulky stable adducts in a human lung cell coculture model

To extend current knowledge on the underlying mechanisms of air pollution particulate matter (PM(2.5))-induced human lung toxicity, the metabolic activation of polycyclic aromatic hydrocarbons (PAH) within PM(2.5) and PAH-DNA bulky stable adduct patterns in human alveolar macrophage (AM) and/or human lung epithelial L132 cells in mono- and cocultures were studied. In the coculture system, only human AM were exposed to air pollution PM(2.5), unlike L132 cells. Particles, inorganic fraction and positive controls [i.e. TiO(2), thermally desorbed PM (dPM) and benzo[a]pyrene, B[a]P, respectively] were included in the experimental design. Cytochrome P450 (CYP) 1A1 gene expression, CYP1A1 catalytic activity and PAH-DNA bulky stable adducts were studied after 24, 48 and/or 72 h. Relatively low doses of PAH within PM(2.5) induced CYP1A1 gene expression and CYP1A1 catalytic activity in human AM and, thereafter, PAH-DNA bulky stable adduct formation. Adduct spots in PM(2.5) -exposed human AM were higher than those in dPM-exposed ones, thereby showing the incomplete removal of PAH by thermal desorption. PAH within air pollution PM(2.5) induced CYP1A1 gene expression but not CYP1A1 catalytic activity in L132 cells. However, despite the absence of PAH-DNA bulky stable adduct in L132 cells from human AM/L132 cell cocultures exposed to dPM(2.5) or PM(2.5), reliable quantifiable PAH-DNA bulky stable adducts were observed in L132 cells from human AM/L132 cell coculture exposed to B[a]P. Taken together, these results support the exertion of genotoxicity of highly reactive B[a]P-derived metabolites produced within human AM not only in primary target human AM, but also in secondary target L132 cells.

Interaction between DMBT1 and galectin 3 is modulated by the structure of the oligosaccharides carried by DMBT1

DMBT1 (deleted in malignant brain tumor 1), a human mucin-like glycoprotein, belonging to the scavenger receptor cysteine-rich (SRCR) superfamily, is mainly secreted from mucosal epithelia. It has been shown previously that interaction of hensin, the rabbit ortholog of DMBT1, with galectin 3, a β-galactoside-binding lectin, induces a terminal differentiation of epithelial cells. In this paper, we have used surface plasmon resonance (SPR), to analyse the binding of galectin 3 to two purified samples of human DMBT1:recombinant DMBT1 produced in CHO cells and DMBT1 isolated from intestinal tissues. Characterization of their glycosylation profile by nano-ESI-Q-TOF tandem mass spectrometry showed significant differences in O-glycans between the two DMBT1 samples. Results obtained by SPR demonstrated that the oligosaccharide side chains of DMBT1 are recognized by the carbohydrate-recognition domain (CRD) of galectin 3 and modification in the pattern of oligosaccharides modulates the binding parameters of DMBT1 with galectin 3. Moreover, using immunohistochemistry on paraffin-embedded colonic tissue sections, we could show a co-localisation of DMBT1 and galectin 3 in human intestine, suggesting a potential physiological interaction.