Rhizobacteria Impact Colonization of Listeria monocytogenes on Arabidopsis thaliana Roots

In spite of its relevance as a foodborne pathogen, we have limited knowledge about Listeria monocytogenes in the environment. L. monocytogenes outbreaks have been linked to fruits and vegetables; thus, a better understanding of the factors influencing its ability to colonize plants is important. We tested how environmental factors and other soil- and plant-associated bacteria influenced L. monocytogenes\u27 ability to colonize plant roots using Arabidopsis thaliana seedlings in a hydroponic growth system. We determined that the successful root colonization of L. monocytogenes 10403S was modestly but significantly enhanced by the bacterium being pregrown at higher temperatures, and this effect was independent of the biofilm and virulence regulator PrfA. We tested 14 rhizosphere-derived bacteria for their impact on L. monocytogenes 10403S, identifying one that enhanced and 10 that inhibited the association of 10403S with plant roots. We also characterized the outcomes of these interactions under both coinoculation and invasion conditions. We characterized the physical requirements of five of these rhizobacteria to impact the association of L. monocytogenes 10403S with roots, visualizing one of these interactions by microscopy. Furthermore, we determined that two rhizobacteria (one an inhibitor, the other an enhancer of 10403S root association) were able to similarly impact 10 different L. monocytogenes strains, indicating that the effects of these rhizobacteria on L. monocytogenes are not strain specific. Taken together, our results advance our understanding of the parameters that affect L. monocytogenes plant root colonization, knowledge that may enable us to deter its association with and, thus, downstream contamination of, food crops. IMPORTANCE Listeria monocytogenes is ubiquitous in the environment, being found in or on soil, water, plants, and wildlife. However, little is known about the requirements for L. monocytogenes\u27 existence in these settings. Recent L. monocytogenes outbreaks have been associated with contaminated produce; thus, we used a plant colonization model to investigate factors that alter L. monocytogenes\u27 ability to colonize plant roots. We show that L. monocytogenes colonization of roots was enhanced when grown at higher temperatures prior to inoculation but did not require a known regulator of virulence and biofilm formation. Additionally, we identified several rhizobacteria that altered the ability of 11 different strains of L. monocytogenes to colonize plant roots. Understanding the factors that impact L. monocytogenes physiology and growth will be crucial for finding mechanisms (whether chemical or microbial) that enable its removal from plant surfaces to reduce L. monocytogenes contamination of produce and eliminate foodborne illness

Intestinal Interleukin-17 Receptor Signaling Mediates Reciprocal Control of the Gut Microbiota and Autoimmune Inflammation

Interleukin-17 (IL-17) and IL-17 receptor (IL-17R) signaling are essential for regulating mucosal host defense against many invading pathogens. Commensal bacteria, especially segmented filamentous bacteria (SFB), are a crucial factor that drives T helper 17 (Th17) cell development in the gastrointestinal tract. In this study, we demonstrate that Th17 cells controlled SFB burden. Disruption of IL-17R signaling in the enteric epithelium resulted in SFB dysbiosis due to reduced expression of α-defensins, Pigr and Nox1. When subjected to experimental autoimmune encephalomyelitis, IL-17R signaling deficient mice demonstrated earlier disease onset and worsened severity that was associated with increased intestinal Csf2 expression and elevated systemic GM-CSF cytokine concentrations. Conditional deletion of IL-17R in the enteric epithelium demonstrated that there was a reciprocal relationship between the gut microbiota and enteric IL-17R signaling that controlled dysbiosis, constrained Th17 development, and regulated the susceptibility to autoimmune inflammation

Environmental factors regulate Paneth cell phenotype and host susceptibility to intestinal inflammation in Irgm1-deficient mice

Crohn's disease (CD) represents a chronic inflammatory disorder of the intestinal tract. Several susceptibility genes have been linked to CD, though their precise role in the pathogenesis of this disorder remains unclear. Immunity-related GTPase M (IRGM) is an established risk allele in CD. We have shown previously that conventionally raised (CV) mice lacking the IRGM ortholog, Irgm1 exhibit abnormal Paneth cells (PCs) and increased susceptibility to intestinal injury. In the present study, we sought to utilize this model system to determine if environmental conditions impact these phenotypes, as is thought to be the case in human CD. To accomplish this, wild-type and Irgm1−/− mice were rederived into specific pathogen-free (SPF) and germ-free (GF) conditions. We next assessed how these differential housing environments influenced intestinal injury patterns, and epithelial cell morphology and function in wild-type and Irgm1−/− mice. Remarkably, in contrast to CV mice, SPF Irgm1−/− mice showed only a slight increase in susceptibility to dextran sodium sulfate-induced inflammation. SPF Irgm1−/− mice also displayed minimal abnormalities in PC number and morphology, and in antimicrobial peptide expression. Goblet cell numbers and epithelial proliferation were also unaffected by Irgm1 in SPF conditions. No microbial differences were observed between wild-type and Irgm1−/− mice, but gut bacterial communities differed profoundly between CV and SPF mice. Specifically, Helicobacter sequences were significantly increased in CV mice; however, inoculating SPF Irgm1−/− mice with Helicobacter hepaticus was not sufficient to transmit a pro-inflammatory phenotype. In summary, our findings suggest the impact of Irgm1-deficiency on susceptibility to intestinal inflammation and epithelial function is critically dependent on environmental influences. This work establishes the importance of Irgm1−/− mice as a model to elucidate host-environment interactions that regulate mucosal homeostasis and intestinal inflammatory responses. Defining such interactions will be essential for developing novel preventative and therapeutic strategies for human CD

Collecting Biospecimens From an Internet-Based Prospective Cohort Study of Inflammatory Bowel Disease (CCFA Partners): A Feasibility Study

BACKGROUND: The Internet has successfully been used for patient-oriented survey research. Internet-based translational research may also be possible. OBJECTIVE: Our aim was to study the feasibility of collecting biospecimens from CCFA Partners, an Internet-based inflammatory bowel disease (IBD) cohort. METHODS: From August 20, 2013, to January 4, 2014, we randomly sampled 412 participants, plus 179 from a prior validation study, and invited them to contribute a biospecimen. Participants were randomized to type (blood, saliva), incentive (none, US $20, or US$50), and collection method for blood. The first 82 contributors were also invited to contribute stool. We used descriptive statistics and t tests for comparisons. RESULTS: Of the 591 participants, 239 (40.4%) indicated interest and 171 (28.9%) contributed a biospecimen. Validation study participants were more likely to contribute than randomly selected participants (44% versus 23%, P<.001). The return rate for saliva was higher than blood collected by mobile phlebotomist and at doctors’ offices (38%, 31%, and 17% respectively, P<.001). For saliva, incentives were associated with higher return rates (43-44% versus 26%, P=.04); 61% contributed stool. Fourteen IBD-associated single nucleotide polymorphisms were genotyped, and risk allele frequencies were comparable to other large IBD populations. Bacterial DNA was successfully extracted from stool samples and was of sufficient quality to permit quantitative polymerase chain reaction for total bacteria. CONCLUSIONS: Participants are willing to contribute and it is feasible to collect biospecimens from an Internet-based IBD cohort. Home saliva kits yielded the highest return rate, though mobile phlebotomy was also effective. All samples were sufficient for genetic testing. These data support the feasibility of developing a centralized collection of biospecimens from this cohort to facilitate IBD translational studies

Akkermansia muciniphila mediates negative effects of IFN gamma on glucose metabolism.

Submitted by Nuzia Santos ([email protected]) on 2017-04-10T19:08:27Z No. of bitstreams: 1 ve_Greer_Renee_Akkermansia_CPqRR_2016.pdf: 8643774 bytes, checksum: 8c546cd3b0da66b7b71d02a3bdd08763 (MD5)Approved for entry into archive by Nuzia Santos ([email protected]) on 2017-04-10T19:29:03Z (GMT) No. of bitstreams: 1 ve_Greer_Renee_Akkermansia_CPqRR_2016.pdf: 8643774 bytes, checksum: 8c546cd3b0da66b7b71d02a3bdd08763 (MD5)Made available in DSpace on 2017-04-10T19:29:03Z (GMT). No. of bitstreams: 1 ve_Greer_Renee_Akkermansia_CPqRR_2016.pdf: 8643774 bytes, checksum: 8c546cd3b0da66b7b71d02a3bdd08763 (MD5) Previous issue date: 2016Oregon State University. College of Veterinary Medicine. Corvallis, Oregon, USAOregon State University. College of Veterinary Medicine. Corvallis, Oregon, USAUniversidade de São Paulo. Escola de Saúde Pública. Departamento de Epidemiologia. São Paulo, SP, BrazilOswaldo Cruz Foundation. René Rachou Research Center. Belo Horizonte, MG, BrasilOregon State University. college of Pharmacy. Corvallis, Oregon, USAOregon State University. College of Veterinary Medicine. Corvallis, Oregon, USAUniversity of North Carolina at Chapel Hill. Division of Pediatric Gastroenterology. Chapel Hill, North Carolina, USAUniversity of São Paulo Medical School. Laboratory of Genetics and Molecular Cardiology. Heart Institute. São Paulo, SP, BrazilUniversity of São Paulo Medical School. Laboratory of Genetics and Molecular Cardiology. Heart Institute. São Paulo, SP, BrazilUniversidade de São Paulo. Escola de Saúde Pública. Departamento de Epidemiologia. São Paulo, SP, BrazilNational Institute of Allergy and Infectious Diseases. Laboratory of Immune Defenses. Mucosal Immunity Section. Bethesda, Maryland , USANational Institute of Allergy and Infectious Diseases. Laboratory of Immune Defenses. Mucosal Immunity Section. Bethesda, Maryland , USANational Institute of Allergy and Infectious Diseases. Laboratory of Immune Defenses. Mucosal Immunity Section. Bethesda, Maryland , USAOregon State University. College of Pharmacy. Corvallis, Oregon, USADuke University Medical Center. Division of Geriatrics and Center for the Study of Aging and Human Development. Departments of Medicine, Molecular Genetics and Microbiology and Immunology. VA Medical Center. Education and Clinical Center. Geriatric Research. Durham, North Carolina, USAUniversity of North Carolina at Chapel Hill. Division of Pediatric Gastroenterology. Chapel Hill, North Carolina, USAOregon State University. College of Pharmacy. Corvallis, Oregon, USAOregon State University. College of Veterinary Medicine. Corvallis, Oregon, USACross-talk between the gut microbiota and the host immune system regulates host metabolism, and its dysregulation can cause metabolic disease. Here, we show that the gut microbe Akkermansia muciniphila can mediate negative effects of IFN gamma on glucose tolerance. In IFN gamma-deficient mice, A. muciniphila is significantly increased and restoration of IFN gamma levels reduces A. muciniphila abundance. We further show that IFN gamma-knockout mice whose microbiota does not contain A. muciniphila do not show improvement in glucose tolerance and adding back A. muciniphila promoted enhanced glucose tolerance. We go on to identify Irgm1 as an IFN gamma-regulated gene in the mouse ileum that controls gut A. muciniphila levels. A. muciniphila is also linked to IFN gamma-regulated gene expression in the intestine and glucose parameters in humans, suggesting that this trialogue between IFN gamma, A. muciniphila and glucose tolerance might be an evolutionally conserved mechanism regulating metabolic health in mice and human

The gene desert mammary carcinoma susceptibility locus Mcs1a regulates Nr2f1 modifying mammary epithelial cell differentiation and proliferation.

Genome-wide association studies have revealed that many low-penetrance breast cancer susceptibility loci are located in non-protein coding genomic regions; however, few have been characterized. In a comparative genetics approach to model such loci in a rat breast cancer model, we previously identified the mammary carcinoma susceptibility locus Mcs1a. We now localize Mcs1a to a critical interval (277 Kb) within a gene desert. Mcs1a reduces mammary carcinoma multiplicity by 50% and acts in a mammary cell-autonomous manner. We developed a megadeletion mouse model, which lacks 535 Kb of sequence containing the Mcs1a ortholog. Global gene expression analysis by RNA-seq revealed that in the mouse mammary gland, the orphan nuclear receptor gene Nr2f1/Coup-tf1 is regulated by Mcs1a. In resistant Mcs1a congenic rats, as compared with susceptible congenic control rats, we found Nr2f1 transcript levels to be elevated in mammary gland, epithelial cells, and carcinoma samples. Chromatin looping over ∼820 Kb of sequence from the Nr2f1 promoter to a strongly conserved element within the Mcs1a critical interval was identified. This element contains a 14 bp indel polymorphism that affects a human-rat-mouse conserved COUP-TF binding motif and is a functional Mcs1a candidate. In both the rat and mouse models, higher Nr2f1 transcript levels are associated with higher abundance of luminal mammary epithelial cells. In both the mouse mammary gland and a human breast cancer global gene expression data set, we found Nr2f1 transcript levels to be strongly anti-correlated to a gene cluster enriched in cell cycle-related genes. We queried 12 large publicly available human breast cancer gene expression studies and found that the median NR2F1 transcript level is consistently lower in 'triple-negative' (ER-PR-HER2-) breast cancers as compared with 'receptor-positive' breast cancers. Our data suggest that the non-protein coding locus Mcs1a regulates Nr2f1, which is a candidate modifier of differentiation, proliferation, and mammary cancer risk