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Alcohol-related liver disease is the most prevalent chronic liver disease worldwide, accounting for 30% of hepatocellular carcinoma (HCC) cases and HCC-specific deaths. However, the knowledge on mechanisms by which alcohol consumption leads to cancer progression and its aggressiveness is limited. Better understanding of the clinical features and the mechanisms of alcohol-induced HCC are of critical importance for prevention and the development of novel treatments.Early stage Huh-7 and advanced SNU449 liver cancer cell lines were subjected to Chronic Alcohol Exposure (CAE), at different doses for 6 months followed by one-month alcohol withdrawal period. ADH activity and ALDH expression were much lower in SNU449 compared with Huh-7 cells and at the 270mM dose, CAE decreased cell viability by about 50% and 80%, respectively in Huh-7 and SNU449 cells but induced mortality only in Huh-7 cells. Thus, Huh-7 may be more vulnerable to ethanol toxicity because of the higher levels of acetaldehyde. CAE induced a dose-dependent increase in cell migration and invasion and also in the expression of Cancer Stem Cells markers (CD133, CD44, CD90). CAE in Huh-7 cells selectively activated ERK1/2 and inhibited GSK3β signaling pathways. Most of the changes induced by CAE were reversed after alcohol withdrawal. Interestingly we confirmed the increase in CD133 mRNA levels in the tumoral tissue of patients with ethanol-related HCC compared to other HCC etiologies.Our results may explain the benefits observed in epidemiological studies showing a significant increase of overall survival in abstinent compared with non-abstinent patients.

BACKGROUND Multiple ethanol binge drinking-like exposures during adolescence in rat induce neuroinflammation, neurogenesis loss and cognitive deficits at adulthood. Interestingly, the very first ethanol binge drinking-like exposures during adolescence also induce cognitive and synaptic plasticity impairments in the hippocampus at short term while the cellular mechanisms of these effects remain unclear. Here, we sought to determine which of the cellular effects of ethanol might play a role in cognitive and synaptic plasticity disturbances observed in adolescent male rat after only two binge-like ethanol exposures. METHODS Using immunochemistry, we determined neurogenesis, neuronal loss, astrogliosis, neuroinflammation and synaptogenesis in the hippocampus of adolescent rat 48h after two binge-like ethanol exposures (3 g/kg, i.p, 9 hours apart). Flow cytometry was used to analyze activated microglia and to identify the TLR4 expressing cell types. RESULTS Increased DCX immunoreactivity was detected in the subgranular zone (SGZ) of the dentate gyrus (DG) together with astrogliosis in the SGZ and a lower number of mature neurons in the DG and in CA3, suggesting compensatory neurogenesis. Synaptic density decreased in the stratum oriens of CA1 revealing structural plasticity. There was no change in microglial TLR4 expression nor in the number of activated microglia, suggesting a lack of neuroinflammatory processes although neuronal TLR4 was decreased in CA1 and DG. CONCLUSIONS Our findings demonstrate that the cognitive deficits associated with hippocampal synaptic plasticity alterations that we previously characterized 48h after the very first binge-like exposures are associated with hippocampal structural plasticity, astrogliosis and decreased neuronal TLR4 expression, but not with microglia reactivity.

Alcohol-related liver disease is the most prevalent chronic liver disease worldwide, accounting for 30% of hepatocellular carcinoma (HCC) cases and HCC-specific deaths. However, the knowledge on mechanisms by which alcohol consumption leads to cancer progression and its aggressiveness is limited. Better understanding of the clinical features and the mechanisms of alcohol-induced HCC are of critical importance for prevention and the development of novel treatments. Early stage Huh-7 and advanced SNU449 liver cancer cell lines were subjected to chronic alcohol exposure (CAE), at different doses for 6 months followed by 1-month alcohol withdrawal period. ADH activity and ALDH expression were much lower in SNU449 compared with Huh-7 cells and at the 270 mM dose, CAE decreased cell viability by about 50% and 80%, respectively, in Huh-7 and SNU449 cells but induced mortality only in Huh-7 cells. Thus, Huh-7 may be more vulnerable to ethanol toxicity because of the higher levels of acetaldehyde. CAE induced a dose-dependent increase in cell migration and invasion and also in the expression of cancer stem cells markers (CD133, CD44, CD90). CAE in Huh-7 cells selectively activated ERK1/2 and inhibited GSK3β signaling pathways. Most of the changes induced by CAE were reversed after alcohol withdrawal. Interestingly, we confirmed the increase in CD133 mRNA levels in the tumoral tissue of patients with ethanol-related HCC compared to other HCC etiologies. Our results may explain the benefits observed in epidemiological studies showing a significant increase of overall survival in abstinent compared with non-abstinent patients.

International audience; Store Operated Calcium Entry (SOCE) is the main route for calcium entry in breast cells. After it’s activation by STromal Interaction Molecule (STIM) during endoplasmic reticulum store depletion, membrane channels ORAI are the main actors of this cell calcium entry. STIM, ORAI and SOCE alterations might contribute to Breast Cancer (BC) carcinogenesis. Recently, we reported the tumor suppressor role of Signaling Lymphocytic Activation Molecule Family member 3 (SLAMF3) on HepatoCellular Carcinoma (HCC) progression. SLAMF3 has been shown to regulate the activity of immune cells by modulating the calcium influx. In this report, we aimed at exploring the role of SLAMF3 in regulating SOCE and migration of BC cells. We quantified and compared the expression of SLAMF3 and STIM1 by quantitative RT-PCR in tumor and healthy resections of 14 patients followed at the University Hospital of Amiens. The expressions of SLAMF3 and STIM1 were also quantified and compared in non-invasive T47D and invasive MDA-MB-231 cell lines by quantitative RT-PCR, Western blot and flow cytometry. We determined the Ca2+ basal entry as well as SOCE by Mn2+ quenching and calcium imaging, respectively, in T47D and MDA-MB-231 cells overexpressing SLAMF3 ectopically. The cell proliferation and migration/invasion were investigated by MTT, wound healing assay and Boyden chambers tests, respectively. First, we report the expression of SLAMF3 in mammary epithelial cells. We highlight the complete loss of SLAMF3 expression in invasive BC cell lines compared to non-invasive cells. In addition, we show that the forced expression of SLAMF3 in invasive cells down-regulate specifically the STIM1 expression in invasive compared to non-invasive mammary cell lines. Interestingly, an inverse correlation is observed between the low expression of SLAMF3 and the high expression of STIM1 in primary human BC tissues. Our results indicate that SLAMF3 reduces SOCE and therefore restricts BC cell migration by decreasing STIM1 expression. Therefore, SLAMF3 might be used as a predictive marker of BC evolution and aggressiveness.

International audience; Simple Summary Sorafenib is a treatment for advanced HCC which demonstrated a poor objective response rate due to important induction of resistance. We demonstrated that induction of acquired-resistance to sorafenib in Huh-7 cell line leads to the loss of SLAMF3 expression, a tumor suppressor receptor in HCC. In these cells, the sorafenib-resistant phenotype is characterized by the increase of aggressiveness and induction of the epithelial-to-mesenchymal transition. Acquired-resistance to sorafenib induce a multipotent mesenchymal stem cells characteristic. Interestingly, SLAMF3 overexpression reversed the epithelial-to-mesenchymal transition and decreased metastatic potential in sorafenib-resistant cells through the control of ERK1/2 and mTOR signaling pathways. SLAMF3 seems to be a theranostics tools to the management of sorafenib treatment. Background: Acquired resistance to sorafenib in hepatocellular carcinoma (HCC) patients results in poor prognosis. Epithelial-to-mesenchymal transition (EMT) is the major mechanism implicated in the resistance to sorafenib. We have reported the tumor suppressor role of SLAMF3 (signaling lymphocytic activation molecules family 3) in HCC progression and highlighted its implication in controlling the MRP-1 transporter activity. These data suggest the implication of SLAMF3 in sorafenib resistance mechanisms. Methods: We evaluated the resistance to sorafenib in Huh-7 cells treated with progressive doses (Res cells). We investigated the link between acquired resistance to sorafenib and SLAMF3 expression by flow cytometry and Western blot methods. Furthermore, we analyzed the EMT and the stem cell potential of cells resistant to sorafenib. Results: Sorafenib resistance was confirmed in Res cells by analyzing the cell viability in the presence of sorafenib. The mesenchymal transition, in Res cells, was confirmed by high migratory index and the expression of EMT antigens. Interestingly, we found that loss of SLAMF3 expression corresponded to sorafenib-resistant phenotypes. The overexpression of SLAMF3 reversed EMT, decreased metastatic potential and inhibited mTOR/ERK1/2 in Res cells. Conclusions: We propose that rescuing SLAMF3 expression in resistant cells could represent a potential therapeutic strategy to enhance sorafenib efficacy in HCC patients.

Tout patient consommateur chronique et excessif d’alcool avec un ictère récent doit être évalué par le score de Maddrey à la recherche d’une hépatite alcoolique aiguë sévère. Les corticostéroïdes représentent le traitement de première ligne, associés à un soutien nutritionnel adapté et à une abstinence alcoolique. La combinaison corticostéroïdes plus N-acétylcystéine (perfusée pendant les cinq premiers jours) améliore la survie à court terme par rapport aux corticostéroïdes seuls, constituant une option thérapeutique de première ligne. La réponse au traitement est évaluée au septième jour par le modèle de Lille inférieur ou égal à 0,45. Le pronostic des patients non répondeurs aux corticostéroïdes avec un modèle de Lille supérieur à 0,45 est sombre avec une survie de 23 % à six mois. Pour des patients non répondeurs aux corticostéroïdes et sélectionnés, la transplantation hépatique précoce améliore significativement la survie à six mois et à long terme.

All chronic and excessive consumer of alcohol with recent jaundice should be assessed using a Maddrey's score for severe acute alcoholic hepatitis. Corticosteroids are the first line of treatment, associated with an appropriate nutritional support and alcohol abstinence. Corticosteroids plus N-acetylcysteine combination improves short-term survival over corticosteroids alone, and could be proposed as a first line therapy. The response to treatment is evaluated at the 7th day of treatment, with the Lille model≤0.45. Prognostic of non-responders to corticosteroids with Lille model>0.45 is dramatically low with 23% survival at 6 month. Early liver transplantation in a selected group of patients with non-response to corticosteroids significantly improves 6th month and long-term survival.

Ethanol (EtOH) induces cognitive impairment through modulation of synaptic plasticity notably in the hippocampus. The cellular mechanism(s) of these EtOH effects may range from synaptic signaling modulation to alterations of the epigenome. Previously, we reported that two binge-like exposures to EtOH (3 g/kg, ip, 9 h apart) in adolescent rats abolished long-term synaptic depression (LTD) in hippocampus slices, induced learning deficits, and increased N-methyl-d-aspartate (NMDA) receptor signaling through its GluN2B subunit after 48 hours. Here, we tested the hypothesis of EtOH-induced epigenetic alterations leading to modulation of GluN2B and GluN2A NMDA receptor subunits. Forty-two days old rats were treated with EtOH or the histone deacetylase inhibitor (HDACi) sodium butyrate (NaB, 600 mg/kg, ip) injected alone or 30 minutes before EtOH. After 48 hours, learning was tested with novel object recognition while synaptic plasticity and the role of GluN2A and GluN2B subunits in NMDA-fEPSP were measured in CA1 field of hippocampus slices. LTD and memory were impaired 48 hours after EtOH and NMDA-fEPSP analysis unraveled changes in the GluN2A/GluN2B balance. These results were associated with an increase in histone deacetylase (HDAC) activity and HDAC2 mRNA and protein while Ac-H4K12 labelling was decreased. EtOH increases expression of HDAC2 and mRNA level for GluN2B subunit (but not GluN2A), while HDAC2 modulates the promoter of the gene encoding GluN2B. Interestingly, NaB pretreatment prevented all the cellular and memory-impairing effects of EtOH. In conclusion, the memory-impairing effects of two binge-like EtOH exposure involve NMDA receptor-dependent LTD deficits due to a GluN2A/GluN2B imbalance resulting from changes in GluN2B expression induced by HDAC2.

All chronic and excessive consumer of alcohol with recent jaundice should be assessed using a Maddrey's score for severe acute alcoholic hepatitis. Corticosteroids are the first line of treatment, associated with an appropriate nutritional support and alcohol abstinence. Corticosteroids plus N-acetylcysteine combination improves short-term survival over corticosteroids alone, and could be proposed as a first line therapy. The response to treatment is evaluated at the 7th day of treatment, with the Lille model≤0.45. Prognostic of non-responders to corticosteroids with Lille model0.45 is dramatically low with 23% survival at 6 month. Early liver transplantation in a selected group of patients with non-response to corticosteroids significantly improves 6th month and long-term survival.

// Gregory Fouquet 1, * , Ingrid Marcq 1, * , Veronique Debuysscher 1 , Jagadeesh Bayry 2 , Amrathlal Rabbind Singh 3 , Abderrahmane Bengrine 4 , Eric Nguyen-Khac 1, 5 , Mickael Naassila 1 and Hicham Bouhlal 1 1 INSERM 1247-GRAP, Centre Universitaire de Recherche en Sante CURS, Universite de Picardie Jules Verne, CHU Sud, Amiens, France 2 INSERM UMRS 1138, Centre de Recherche des Cordeliers–Paris, Paris, France 3 Department of Microbiology, Aravind Medical Research Foundation, Anna Nagar, Madurai-India 4 Biobanque de Picardie, Centre Hospitalier Universitaire Sud, Amiens, France 5 Service Hepato-Gastroenterologie, Centre Hospitalier Universitaire Sud, Amiens, France * These authors contributed equally to this work Correspondence to: Hicham Bouhlal, email: hicham.bouhlal@u-picardie.fr Ingrid Marcq, email: Ingrid.marcq@u-picardie.fr Keywords: SLAMF molecules; cancer; pathophysiology; therapy Received: October 19, 2016 Accepted: December 03, 2017 Epub: February 26, 2018 Published: March 23, 2018 ABSTRACT Signaling Lymphocytic Activation Molecules (SLAM) family receptors are initially described in immune cells. These receptors recruit both activating and inhibitory SH2 domain containing proteins through their Immunoreceptor Tyrosine based Switch Motifs (ITSMs). Accumulating evidence suggest that the members of this family are intimately involved in different physiological and pathophysiological events such as regulation of immune responses and entry pathways of certain viruses. Recently, other functions of SLAM, principally in the pathophysiology of neoplastic transformations have also been deciphered. These new findings may prompt SLAM to be considered as new tumor markers, diagnostic tools or potential therapeutic targets for controlling the tumor progression. In this review, we summarize the major observations describing the implications and features of SLAM in oncology and discuss the therapeutic potential attributed to these molecules.

// Hicham Bouhlal 1, 2 , Hakim Ouled-Haddou 1, * , Veronique Debuysscher 1, * , Amrathlal Rabbind Singh 1 , Christele Ossart 1, 2 , Aline Reignier 1, 2 , Hakim Hocini 3 , Gregory Fouquet 1 , Mohammed Al Baghami 1, 2 , Melanie Simoes Eugenio 1 , Eric Nguyen-Khac 4 , Jean-Marc Regimbeau 5 , Ingrid Marcq 1 1 Centre Universitaire de Recherche en Sante CURS, CAP-Sante (FED 4231), Universite de Picardie Jules Verne, CHU Sud, Amiens, France 2 Service d’Hematologie Clinique et de Therapie Cellulaire Centre Hospitalier Universitaire Sud, Amiens, France 3 IMRB, Equipe 16, Genomique Medicale, UFR de Medecine, Creteil, France 4 Service Hepato-Gastroenterologie, Centre Hospitalier Universitaire Sud, Amiens, France 5 Service de Chirurgie Digestive Centre Hospitalier Universitaire Sud, Amiens, France * These authors contributed equally to this work Correspondence to: Hicham Bouhlal, e-mail: hicham.bouhlal@u-picardie.fr Amrathlal Rabbind Singh, e-mail: rabbind@gmail.com Ingrid Marcq, e-mail: ingrid.marcq@u-picardie.fr Keywords: SLAMF3, HCC, retinoblastoma factor RB, polo-like kinase 1 (PLK1), mitosis Received: June 18, 2015 Accepted: December 09, 2015 Published: January 20, 2016 ABSTRACT Polo-like kinase PLK1 is a cell cycle protein that plays multiple roles in promoting cell cycle progression. Among the many roles, the most prominent role of PLK1 is to regulate the mitotic spindle formation checkpoint at the M-phase. Recently we reported the expression of SLAMF3 in Hepatocytes and show that it is down regulated in tumor cells of hepatocellular carcinoma (HCC). We also show that the forced high expression level of SLAMF3 in HCC cells controls proliferation by inhibiting the MAPK ERK/JNK and the mTOR pathways. In the present study, we provide evidence that the inhibitory effect of SLAMF3 on HCC proliferation occurs through Retinoblastoma (RB) factor and PLK1-dependent pathway. In addition to the inhibition of MAPK ERK/JNK and the mTOR pathways, expression of SLAMF3 in HCC retains RB factor in its hypophosphorylated active form, which in turn inactivates E2F transcription factor, thereby repressing the expression and activation of PLK1. A clear inverse correlation was also observed between SLAMF3 and PLK expression in patients with HCC. In conclusion, the results presented here suggest that the tumor suppressor potential of SLAMF3 occurs through activation of RB that represses PLK1. We propose that the induction of a high expression level of SLAMF3 in cancerous cells could control cellular mitosis and block tumor progression.

International audience; Multidrug resistance MDR proteins (MRPs) are members of the C family of a group of proteins named ATP binding cassette (ABC) transporters. MRPs can transport drugs including anticancer drugs, nucleoside analogs, antimetabolites and tyrosine kinase inhibitors. Drugs used in HCC therapy, such as tyrosine kinase inhibitor sorafenib, are substrates of uptake and/or efflux transporters. Variable expression of MRPs at the plasma membrane of tumor cells may contribute to drug resistance and subsequent clinical response. Recently, we reported that the hepatocyte SLAMF3 expression (Signaling Lymphocytic Activation Molecule Family member 3) was reduced in tumor cells from hepatocellular carcinoma (HCC) compared to its high expression in adjacent tissues. In the present study, we make a strong correlation between induced SLAMF3 overexpression and the specific loss of MRP-1 expression and its functionalities as a drugs resistance transporter. No changes were observed on expression of ABCG2 and MDR. More importantly, we highlight a strong inverse correlation between MRP-1 and SLAMF3 expression in patients with HCC. We propose that the SLAMF3 overexpression in cancerous cells could represent a potential therapeutic strategy to improve the drugs sensibility of resistant cells and thus control the therapeutic failure in HCC patients.

Objective:The results of clinical applications of human Mesenchymal Stem Cells (hMSCs) depend on clinical and biological factors. The quality of stem cell culture will affect success rate. Stem cell culture contamination by fibroblasts can be happened. The identification of the differences between these two cell types plays an important role to improve the quality of the therapeutic uses of hMSCs. Our present work is the first work to compare the phenotype and functional properties of primary human Dermal fibroblasts HDF to hMSC from Bone Marrow BM to reflect the impact of the possible contamination of bone morrow derived hMSC (BM-hMSC) by fibroblasts.Methods:In this study, hMSCs were obtained from the BM of (Healthy donor, n= 5) and compared to primary HDF. The following parameters were used for this comparison: cell morphology, cell proliferation tests, cell cycle, immunophenotype, pluripotent and differentiation capacity into osteoblastic and adipogenic lineages. Genes expression profile was determined in BM-MSCs and HDF by Q-PCR.Results:Our results show that both of BM-hMSCs and HDF cells have homogenous fusiform, fibroblast-like appearance. Human derived fibroblasts showed, significantly (p

Sorafenib is the treatment of reference for advanced hepatocellular carcinoma (HCC), the most frequent form of primary liver tumour. The loss of function of the retinoblastoma (Rb) protein is an important event during liver carcinogenesis, but it is unclear whether the Rb status modulates the response of HCC cells to sorafenib. Here, we examined this question in HCC cells with reduced levels of Rb achieved through stable RNA interference. We show that HCC cells with reduced levels of Rb exhibit a two- to threefold increase in cell death induction upon exposure to sorafenib compared with controls. Sorafenib treatment of Balb/c nude mice that received tumour xenografts derived from HCC cells with reduced Rb levels resulted in complete tumour regression in 50% of the animals treated, compared with tumour stabilization in mice that received control cells. We show that, upon exposure to sorafenib, the Rb-negative status of HCC cells promotes the occurrence of ferroptosis, a form of oxidative necrosis. The findings highlight the role of Rb in the response of HCC cells to sorafenib and the regulation of ferroptosis.

International audience; The neonatal gut is rapidly colonized by a newly dominant group of commensal Escherichia coli strains among which a large proportion produces a genotoxin called colibactin. In order to analyze the short- and long-term effects resulting from such evolution, we developed a rat model mimicking the natural transmission of E. coli from mothers to neonates. Genotoxic and non-genotoxic E. coli strains were equally transmitted to the offspring and stably colonized the gut across generations. DNA damage was only detected in neonates colonized with genotoxic E. coli strains. Signs of genotoxic stress such as anaphase bridges, higher occurrence of crypt fission and accelerated renewal of the mature epithelium were detected at adulthood. In addition, we observed alterations of secretory cell populations and gut epithelial barrier. Our findings illustrate how critical is the genotype of E. coli strains acquired at birth for gut homeostasis at adulthood.

International audience; Sepsis is a life-threatening infection. Escherichia coli is the first known cause of bacteremia leading to sepsis. Lymphopenia was shown to predict bacteremia better than conventional markers of infection. The pks genomic island, which is harbored by extraintestinal pathogenic E. coli (ExPEC) and encodes the genotoxin colibactin, is epidemiologically associated with bacteremia. To investigate a possible relationship between colibactin and lymphopenia, we examined the effects of transient infection of lymphocytes with bacteria that were and those that were not producing the genotoxin. A mouse model of sepsis was used to compare the virulence of a clinical ExPEC isolate with its isogenic mutant impaired for the production of colibactin. We observed that colibactin induced double-strand breaks in the DNA of infected lymphocytes, leading to cell cycle arrest and to cell death by apoptosis. E. coli producing colibactin induced a more profound lymphopenia in septicemic mice, compared with the isogenic mutant unable to produce colibactin. In a sepsis model in which the mice were treated by rehydration and antibiotics, the production of colibactin by the bacteria was associated with a significantly lower survival rate. In conclusion, we demonstrate that production of colibactin by E. coli exacerbates lymphopenia associated with septicemia and could impair the chances to survive sepsis.

International audience; Hepatitis C virus (HCV) is a leading cause of cirrhosis and liver cancer worldwide. We recently characterized for the first time the expression of Signaling Lymphocyte Activating Molecule 3 (SLAMF3) in human hepatocytes and here, we report that SLAMF3 interacts with the HCV viral protein E2 and is implicated in HCV entry process. We found a strong correlation between SLAMF3 expression level and hepatocyte susceptibility to HCV infection. The use of specific siRNAs to down-modulate SLAMF3 expression and SLAMF3-blocking antibodies both decreased the hepatocytes susceptibility to HCV infection. Moreover, SLAMF3 over-expression significantly increased susceptibility to HCV infection. Interestingly, experiments with peptides derived from each SLAMF3 domain showed that the first N-terminal extracellular domain is essential for interaction with HCV particles. Finally, we showed that recombinant HCV envelop protein E2 can bind SLAMF3 and that anti-SLAMF3 antibodies inhibited specifically this interaction. Overall, our results revealed that SLAMF3 plays a role during HCV entry, likely by enhancing entry of viral particle within hepatocytes.

In Escherichia coli, the biosynthetic pathways of several small iron-scavenging molecules known as siderophores (enterobactin, salmochelins and yersiniabactin) and of a genotoxin (colibactin) are known to require a 4′-phosphopantetheinyl transferase (PPTase). Only two PPTases have been clearly identified: EntD and ClbA. The gene coding for EntD is part of the core genome of E. coli, whereas ClbA is encoded on the pks pathogenicity island which codes for colibactin. Interestingly, the pks island is physically associated with the high pathogenicity island (HPI) in a subset of highly virulent E. coli strains. The HPI carries the gene cluster required for yersiniabactin synthesis except for a gene coding its cognate PPTase. Here we investigated a potential interplay between the synthesis pathways leading to the production of siderophores and colibactin, through a functional interchangeability between EntD and ClbA. We demonstrated that ClbA could contribute to siderophores synthesis. Inactivation of both entD and clbA abolished the virulence of extra-intestinal pathogenic E. coli (ExPEC) in a mouse sepsis model, and the presence of either functional EntD or ClbA was required for the survival of ExPEC in vivo. This is the first report demonstrating a connection between multiple phosphopantetheinyl-requiring pathways leading to the biosynthesis of functionally distinct secondary metabolites in a given microorganism. Therefore, we hypothesize that the strict association of the pks island with HPI has been selected in highly virulent E. coli because ClbA is a promiscuous PPTase that can contribute to the synthesis of both the genotoxin and siderophores. The data highlight the complex regulatory interaction of various virulence features with different functions. The identification of key points of these networks is not only essential to the understanding of ExPEC virulence but also an attractive and promising target for the development of anti-virulence therapy strategies., Author Summary The synthesis of numerous molecules involved in the virulence potential and fitness of pathogenic bacteria requires a particular enzyme family, i.e. phosphopantetheinyl transferases (PPTases). To date, the synthesis of a given bioactive metabolite was thought to require a specific PPTase. As PPTases are being investigated as promising targets for antibacterial development, we addressed the question of a possible functional interchangeability between PPTases in Escherichia coli. PPTases are known to be involved in the synthesis of low-molecular weight iron chelators (siderophores), and of a genotoxin named colibactin. Here we demonstrated interplay between the synthesis pathways leading to the production of siderophores and of colibactin. We showed that inactivation of both PPTases abolished the virulence of extra-intestinal pathogenic E. coli (ExPEC) in a mouse sepsis model. To our knowledge, this is the first demonstration of interplay between multiple PPTases-requiring pathways leading to the biosynthesis of functionally distinctive virulence factors, in a given microorganism. The extensive substrate specificity of PPTase ClbA could account for the co-selection and co-evolution of genomic islands encoding colibactin and yersiniabactin siderophore.

International audience; Oral administration of the probiotic bacterium Escherichia coli Nissle 1917 improves chronic inflammatory bowel diseases, but the molecular basis for this therapeutic efficacy is unknown. E. coli Nissle 1917 harbors a cluster of genes coding for the biosynthesis of hybrid nonribosomal peptide-polyketide(s). This biosynthetic pathway confers the ability for bacteria to induce DNA double strand breaks in eukaryotic cells. Here we reveal that inactivation of the clbA gene within this genomic island abrogated the ability for the strain to induce DNA damage and chromosomal abnormalities in non-transformed cultured rat intestinal epithelial cells but is required for the probiotic activity of E. coli Nissle 1917. Thus, evaluation of colitis severity induced in rodent fed with E. coli Nissle 1917 or an isogenic non-genotoxic mutant demonstrated the need for a functional biosynthetic pathway both in the amelioration of the disease and in the modulation of cytokine expression. Feeding rodents with a complemented strain for which genotoxicity was restored confirmed that this biosynthetic pathway contributes to the health benefits of the probiotic by modulating its immunomodulatory properties. Our data provide additional evidence for the benefit of this currently used probiotic in colitis but remind us that an efficient probiotic may also have side effects as any other medication.

Escherichia coli induces DNA double strand breaks in gut cells and triggers genomic instability Gabriel Cuevas-Ramos, Claude Petit, Ingrid Marcq, Fabrice Pierre, Michele Boury, Eric Oswald, Jean-Philippe Nougayrede* INRA, UMR1225, ENVT, Toulouse F-31076, France *jp.nougayrede@envt.fr