Publications by authors named "Kathryn A Eaton"

72 Publications

Dendritic cell-derived TGF-β mediates the induction of mucosal regulatory T-cell response to Helicobacter infection essential for maintenance of immune tolerance in mice.

Helicobacter 2020 Dec 6;25(6):e12763. Epub 2020 Oct 6.

Department of Internal Medicine (Division of Gastroenterology), University of Michigan Health System, Ann Arbor, MI, USA.

Background: Helicobacter pylori infection leads to regulatory T-cell (Treg) induction in infected mice, which contributes to H. pylori immune escape. However, the mechanisms responsible for H. pylori induction of Treg and immune tolerance remain unclear. We hypothesized DC-produced TGF-β may be responsible for Treg induction and immune tolerance.

Materials And Methods: To test this hypothesis, we generated TGF-β mice (CD11c DC-specific TGF-β deletion) and assessed the impact of DC-specific TGF-β deletion on DC function during Helicobacter infection in vitro and in vivo. To examine the T cell-independent DC function, we crossed TGF-β mice onto Rag1KO background to generate TGF-β xRag1KO mice.

Results: When stimulated with H. pylori, TGF-β BMDC/splenocyte cocultures showed increased levels of proinflammatory cytokines and decreased levels of anti-inflammatory cytokines compared to control, indicating a proinflammatory DC phenotype. Following 6 months of H. felis infection, TGF-β mice developed more severe gastritis and a trend toward more metaplasia compared to TGF-β with increased levels of inflammatory Th1 cytokine mRNA and lower gastric H. felis colonization compared to infected TGF-β mice. In a T cell-deficient background using TGF-β xRag1KO mice, H. felis colonization was significantly lower when DC-derived TGF-β was absent, revealing a direct, innate function of DC in controlling H. felis infection independent of Treg induction.

Conclusions: Our findings indicate that DC-derived TGF-β mediates Helicobacter-induced Treg response and attenuates the inflammatory Th1 response. We also demonstrated a previously unrecognized innate role of DC controlling Helicobacter colonization via a Treg-independent mechanism. DC TGF-β signaling may represent an important target in the management of H. pylori.
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http://dx.doi.org/10.1111/hel.12763DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7885176PMC
December 2020

The Gene Expression Profile of Uropathogenic Escherichia coli in Women with Uncomplicated Urinary Tract Infections Is Recapitulated in the Mouse Model.

mBio 2020 08 11;11(4). Epub 2020 Aug 11.

Department of Microbiology and Immunology, University of Michigan, Ann Arbor, Michigan, USA

Uropathogenic (UPEC) is the primary causative agent of uncomplicated urinary tract infections (UTIs). UPEC fitness and virulence determinants have been evaluated in a variety of laboratory settings, including a well-established mouse model of UTI. However, the extent to which bacterial physiologies differ between experimental models and human infections remains largely understudied. To address this important issue, we compared the transcriptomes of three different UPEC isolates in human infection and under a variety of laboratory conditions, including LB culture, filter-sterilized urine culture, and the UTI mouse model. We observed high correlation in gene expression between the mouse model and human infection in all three strains examined (Pearson correlation coefficients of 0.86 to 0.87). Only 175 of 3,266 (5.4%) genes shared by all three strains had significantly different expression levels, with the majority of them (145 genes) downregulated in patients. Importantly, gene expression levels of both canonical virulence factors and metabolic machinery were highly similar between the mouse model and human infection, while the conditions displayed more substantial differences. Interestingly, comparison of gene expression between the mouse model and human infection hinted at differences in bladder oxygenation as well as nutrient composition. In summary, our work strongly validates the continued use of this mouse model for the study of the pathogenesis of human UTI. Different experimental models have been used to study UPEC pathogenesis, including cultures in different media, tissue culture, and mouse models of infection. The last is especially important since it allows evaluation of mechanisms of pathogenesis and potential therapeutic strategies against UPEC. Bacterial physiology is greatly shaped by environment, and it is therefore critical to understand how closely bacterial physiology in any experimental model relates to human infection. In this study, we found strong correlation in bacterial gene expression between the mouse model and human UTI using identical strains, suggesting that the mouse model accurately mimics human infection, definitively supporting its continued use in UTI research.
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http://dx.doi.org/10.1128/mBio.01412-20DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7439467PMC
August 2020

The Intermucosal Connection between the Mouth and Gut in Commensal Pathobiont-Driven Colitis.

Cell 2020 07 16;182(2):447-462.e14. Epub 2020 Jun 16.

Division of Gastroenterology and Hepatology, Department of Internal Medicine, University of Michigan, Ann Arbor, MI, USA. Electronic address:

The precise mechanism by which oral infection contributes to the pathogenesis of extra-oral diseases remains unclear. Here, we report that periodontal inflammation exacerbates gut inflammation in vivo. Periodontitis leads to expansion of oral pathobionts, including Klebsiella and Enterobacter species, in the oral cavity. Amassed oral pathobionts are ingested and translocate to the gut, where they activate the inflammasome in colonic mononuclear phagocytes, triggering inflammation. In parallel, periodontitis results in generation of oral pathobiont-reactive Th17 cells in the oral cavity. Oral pathobiont-reactive Th17 cells are imprinted with gut tropism and migrate to the inflamed gut. When in the gut, Th17 cells of oral origin can be activated by translocated oral pathobionts and cause development of colitis, but they are not activated by gut-resident microbes. Thus, oral inflammation, such as periodontitis, exacerbates gut inflammation by supplying the gut with both colitogenic pathobionts and pathogenic T cells.
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http://dx.doi.org/10.1016/j.cell.2020.05.048DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7414097PMC
July 2020

Gut Microbiota Modulate CD8 T Cell Responses to Influence Colitis-Associated Tumorigenesis.

Cell Rep 2020 04;31(1):107471

Graduate Program in Immunology, University of Michigan, Ann Arbor, MI 48109, USA; Department of Internal Medicine, University of Michigan, Ann Arbor, MI 48109, USA. Electronic address:

There is increasing evidence that gut microbiome perturbations, also known as dysbiosis, can influence colorectal cancer development. To understand the mechanisms by which the gut microbiome modulates cancer susceptibility, we examine two wild-type mouse colonies with distinct gut microbial communities that develop significantly different tumor numbers using a mouse model of inflammation-associated tumorigenesis. We demonstrate that adaptive immune cells contribute to the different tumor susceptibilities associated with the two microbial communities. Mice that develop more tumors have increased colon lamina propria CD8 IFNγ T cells before tumorigenesis but reduced CD8 IFNγ T cells in tumors and adjacent tissues compared with mice that develop fewer tumors. Notably, intratumoral T cells in mice that develop more tumors exhibit increased exhaustion. Thus, these studies suggest that microbial dysbiosis can contribute to colon tumor susceptibility by hyperstimulating CD8 T cells to promote chronic inflammation and early T cell exhaustion, which can reduce anti-tumor immunity.
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http://dx.doi.org/10.1016/j.celrep.2020.03.035DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7934571PMC
April 2020

Interleukin-22-mediated host glycosylation prevents Clostridioides difficile infection by modulating the metabolic activity of the gut microbiota.

Nat Med 2020 04 17;26(4):608-617. Epub 2020 Feb 17.

Division of Gastroenterology, University of Michigan Medical School, Ann Arbor, MI, USA.

The involvement of host immunity in the gut microbiota-mediated colonization resistance to Clostridioides difficile infection (CDI) is incompletely understood. Here, we show that interleukin (IL)-22, induced by colonization of the gut microbiota, is crucial for the prevention of CDI in human microbiota-associated (HMA) mice. IL-22 signaling in HMA mice regulated host glycosylation, which enabled the growth of succinate-consuming bacteria Phascolarctobacterium spp. within the gut microbiome. Phascolarctobacterium reduced the availability of luminal succinate, a crucial metabolite for the growth of C. difficile, and therefore prevented the growth of C. difficile. IL-22-mediated host N-glycosylation is likely impaired in patients with ulcerative colitis (UC) and renders UC-HMA mice more susceptible to CDI. Transplantation of healthy human-derived microbiota or Phascolarctobacterium reduced luminal succinate levels and restored colonization resistance in UC-HMA mice. IL-22-mediated host glycosylation thus fosters the growth of commensal bacteria that compete with C. difficile for the nutritional niche.
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http://dx.doi.org/10.1038/s41591-020-0764-0DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7160049PMC
April 2020

Dietary L-serine confers a competitive fitness advantage to Enterobacteriaceae in the inflamed gut.

Nat Microbiol 2020 01 4;5(1):116-125. Epub 2019 Nov 4.

Division of Gastroenterology, Department of Internal Medicine, University of Michigan, Ann Arbor, MI, USA.

Metabolic reprogramming is associated with the adaptation of host cells to the disease environment, such as inflammation and cancer. However, little is known about microbial metabolic reprogramming or the role it plays in regulating the fitness of commensal and pathogenic bacteria in the gut. Here, we report that intestinal inflammation reprograms the metabolic pathways of Enterobacteriaceae, such as Escherichia coli LF82, in the gut to adapt to the inflammatory environment. We found that E. coli LF82 shifts its metabolism to catabolize L-serine in the inflamed gut in order to maximize its growth potential. However, L-serine catabolism has a minimal effect on its fitness in the healthy gut. In fact, the absence of genes involved in L-serine utilization reduces the competitive fitness of E. coli LF82 and Citrobacter rodentium only during inflammation. The concentration of luminal L-serine is largely dependent on dietary intake. Accordingly, withholding amino acids from the diet markedly reduces their availability in the gut lumen. Hence, inflammation-induced blooms of E. coli LF82 are significantly blunted when amino acids-particularly L-serine-are removed from the diet. Thus, the ability to catabolize L-serine increases bacterial fitness and provides Enterobacteriaceae with a growth advantage against competitors in the inflamed gut.
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http://dx.doi.org/10.1038/s41564-019-0591-6DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6925351PMC
January 2020

A Rare Opportunist, , Decreases Severity of Polymicrobial Catheter-Associated Urinary Tract Infection.

Infect Immun 2019 12 17;88(1). Epub 2019 Dec 17.

Department of Microbiology and Immunology, Jacobs School of Medicine and Biomedical Sciences, State University of New York at Buffalo, Buffalo, New York, USA

Catheter-associated urinary tract infections (CAUTIs) are common hospital-acquired infections and frequently polymicrobial, which complicates effective treatment. However, few studies experimentally address the consequences of polymicrobial interactions within the urinary tract, and the clinical significance of polymicrobial bacteriuria is not fully understood. is one of the most common causes of monomicrobial and polymicrobial CAUTI and frequently cocolonizes with , , , and infections are particularly challenging due to its potent urease enzyme, which facilitates formation of struvite crystals, catheter encrustation, blockage, and formation of urinary stones. We previously determined that interactions between and other uropathogens can enhance urease activity, resulting in greater disease severity during experimental polymicrobial infection. Our present work reveals that acts on in a contact-independent manner to decrease urease activity. Furthermore, actively prevents urease enhancement by , , and Importantly, these interactions translate to modulation of disease severity during experimental CAUTI, predominantly through a urease-dependent mechanism. Thus, products secreted by multiple bacterial species in the milieu of the catheterized urinary tract can directly impact prognosis.
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http://dx.doi.org/10.1128/IAI.00691-19DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6921659PMC
December 2019

Characterizing intestinal strictures of Crohn's disease by endoscopic photoacoustic imaging.

Biomed Opt Express 2019 May 24;10(5):2542-2555. Epub 2019 Apr 24.

Department of Radiology, University of Michigan Medical School, Ann Arbor, MI 48109, USA.

Crohn's disease (CD) is one type of inflammatory bowel disease where both inflammation and fibrosis cause the thickening of the bowel wall and development of the strictures. Accurate assessment of the strictures is critical for the management of CD because the fibrotic strictures must be removed surgically. In this study, a prototype capsule-shaped acoustic resolution photoacoustic (PA) endoscope, which can perform mulitwavelength side-view scanning, was developed to characterize the intestinal strictures of CD. The imaging performance of the probe was tested in phantom experiments and a rabbit trinitrobenzene sulfonic acid (TNBS) model with acute (inflammatory only) or chronic (mixed fibrotic and inflammatory) colitis . The motion artifacts due to intestinal peristalsis and the respiratory motion of the animals were compensated to improve image qualities. Quantitative molecular component images derived from multi-wavelength PA measurements of normal, acute and chronic intestinal strictures demonstrated statistically significant differences among the three groups that were confirmed by histopathology. A longitudinal study demonstrated the capability of the system in monitoring the development of fibrosis. The results suggest that the proposed novel, capsule-shaped acoustic resolution PA endoscope can be used to characterize fibrostenotic disease .
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http://dx.doi.org/10.1364/BOE.10.002542DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6524586PMC
May 2019

Regulation of Gastric Lgr5+ve Cell Homeostasis by Bone Morphogenetic Protein (BMP) Signaling and Inflammatory Stimuli.

Cell Mol Gastroenterol Hepatol 2018 31;5(4):523-538. Epub 2018 Jan 31.

Department of Internal Medicine, University of Michigan Medical Center, Ann Arbor, Michigan.

Background & Aims: Gastric Leucine-rich repeat-containing G-protein-coupled receptor 5 (Lgr5) cells exert important functions during injury and homeostasis. Bone morphogenetic protein (BMP) signaling regulates gastric inflammation and epithelial homeostasis. We investigated if BMP signaling controls the fate of Lgr5 cells during inflammation.

Methods: The promoter was used to express the BMP inhibitor noggin () in the stomach ( mice). Inhibition of BMP signaling in Lgr5 cells was achieved by crossing () mice to mice with floxed alleles of BMP receptor 1A ( mice). Lgr5/GFP cells were isolated using flow cytometry. Lineage tracing studies were conducted by crossing mice to mice that express and (). Infection with was used to induce inflammation. Morphology of the mucosa was analyzed by H&E staining. Distribution of H/K-adenosine triphosphatase-, IF-, Ki67-, CD44-, CD44v9-, and bromodeoxyuridine-positive cells was analyzed by immunostaining. Expression of neck and pit cell mucins was determined by staining with the lectins Griffonia (Bandeiraea) simplicifolia lectin II and Ulex europaeus agglutinin 1, respectively. , , , , and messenger RNAs were measured by quantitative reverse-transcription polymerase chain reaction.

Results: mice showed diminished expression of in Lgr5/GFP cells. Infection of mice with led to enhanced inflammation, increased cell proliferation, parietal cell loss, and to the development of metaplasia and dysplasia. Infected mice, but not control mice, showed the presence of tomato glands lining the lesser curvature that stained positively with Griffonia (Bandeiraea) simplicifolia lectin II and Ulex europaeus agglutinin 1, and with anti-IF, -CD44, -CD44v9, and -bromodeoxyuridine antibodies.

Conclusions: Inflammation and inhibition of BMP signaling activate Lgr5 cells, which give rise to metaplastic, dysplastic, proliferating lineages that express markers of mucus neck and zymogenic cell differentiation.
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http://dx.doi.org/10.1016/j.jcmgh.2018.01.007DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6009760PMC
January 2018

NLRP6 Protects Il10 Mice from Colitis by Limiting Colonization of Akkermansia muciniphila.

Cell Rep 2017 04;19(4):733-745

Division of Hematology/Oncology, Department of Internal Medicine University of Michigan, Ann Arbor, MI 48109, USA. Electronic address:

Dysfunction in host immune responses and pathologic alterations in the gut microbiota, referred to as dysbiosis, can both contribute to the development of inflammatory bowel disease (IBD). However, it remains unclear how specific changes in host immunity or the microbiota cause disease. We previously demonstrated that the loss of the innate immune receptor NLRP6 in mice resulted in impaired production of interleukin-18 (IL-18) and increased susceptibility to epithelial-induced injury. Here, we show that NLRP6 is important for suppressing the development of spontaneous colitis in the Il10 mice model of IBD and that NLRP6 deficiency results in the enrichment of Akkermansia muciniphila. A. muciniphila was sufficient for promoting intestinal inflammation in both specific-pathogen-free and germ-free Il10 mice. Our results demonstrate that A. muciniphila can act as a pathobiont to promote colitis in a genetically susceptible host and that NLRP6 is a key regulator of its abundance.
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http://dx.doi.org/10.1016/j.celrep.2017.03.080DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC5528001PMC
April 2017

Reduced infectivity of waterborne viable but nonculturable Helicobacter pylori strain SS1 in mice.

Helicobacter 2017 Aug 24;22(4). Epub 2017 Apr 24.

Department of Environmental Health Sciences, University of Michigan, Ann Arbor, MI, USA.

Background: Helicobacter pylori infection has been consistently associated with lack of access to clean water and proper sanitation, but no studies have demonstrated that the transmission of viable but nonculturable (VBNC) H. pylori can occur from drinking contaminated water. In this study, we used a laboratory mouse model to test whether waterborne VBNCH. pylori could cause gastric infection.

Materials And Methods: We performed five mouse experiments to assess the infectivity of VBNCH. pylori in various exposure scenarios. VBNC viability was examined using Live/Dead staining and Biolog phenotype metabolism arrays. High doses of VBNCH. pylori in water were chosen to test the "worst-case" scenario for different periods of time. One experiment also investigated the infectious capabilities of VBNC SS1 using gavage. Further, immunocompromised mice were exposed to examine infectivity among potentially vulnerable groups. After exposure, mice were euthanized and their stomachs were examined for H. pylori infection using culture and PCR methodology.

Results: VBNC cells were membrane intact and retained metabolic activity. Mice exposed to VBNCH. pylori via drinking water and gavage were not infected, despite the various exposure scenarios (immunocompromised, high doses) that might have permitted infection with VBNCH. pylori. The positive controls exposed to viable, culturable H. pylori did become infected.

Conclusions: While other studies that have used viable, culturable SS1 via gavage or drinking water exposures to successfully infect mice, in our study, waterborne VBNC SS1 failed to colonize mice under all test conditions. Future studies could examine different H. pylori strains in similar exposure scenarios to compare the relative infectivity of the VBNC vs the viable, culturable state, which would help inform future risk assessments of H. pylori in water.
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http://dx.doi.org/10.1111/hel.12391DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC5518193PMC
August 2017

Host Determinants of Expression of the Helicobacter pylori BabA Adhesin.

Sci Rep 2017 04 18;7:46499. Epub 2017 Apr 18.

Center for Comparative Medicine, University of California, Davis, School of Medicine, Davis, CA 95616, USA.

Expression of the Helicobacter pylori blood group antigen binding adhesin A (BabA) is more common in strains isolated from patients with peptic ulcer disease or gastric cancer, rather than asymptomatic colonization. Here we used mouse models to examine host determinants that affect H. pylori BabA expression. BabA expression was lost by phase variation as frequently in WT mice as in RAG2-/- mice that do not have functional B or T cells, and in MyD88-/-, TLR2-/- and TLR4-/- mice that are defective in toll like receptor signaling. The presence of other bacteria had no effect on BabA expression as shown by infection of germ free mice. Moreover, loss of BabA expression was not dependent on Le expression or the capacity of BabA to bind Le. Surprisingly, gender was the host determinant most associated with loss of BabA expression, which was maintained to a greater extent in male mice and was associated with greater bacterial load. These results suggest the possibility that loss of BabA expression is not driven by adaptive immunity or toll-like receptor signaling, and that BabA may have other, unrecognized functions in addition to serving as an adhesin that binds Le.
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http://dx.doi.org/10.1038/srep46499DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC5394467PMC
April 2017

The Pathogenic Potential of Proteus mirabilis Is Enhanced by Other Uropathogens during Polymicrobial Urinary Tract Infection.

Infect Immun 2017 02 26;85(2). Epub 2017 Jan 26.

Department of Microbiology and Immunology, University of Michigan Medical School, Ann Arbor, Michigan, USA

Urinary catheter use is prevalent in health care settings, and polymicrobial colonization by urease-positive organisms, such as Proteus mirabilis and Providencia stuartii, commonly occurs with long-term catheterization. We previously demonstrated that coinfection with P. mirabilis and P. stuartii increased overall urease activity in vitro and disease severity in a model of urinary tract infection (UTI). In this study, we expanded these findings to a murine model of catheter-associated UTI (CAUTI), delineated the contribution of enhanced urease activity to coinfection pathogenesis, and screened for enhanced urease activity with other common CAUTI pathogens. In the UTI model, mice coinfected with the two species exhibited higher urine pH values, urolithiasis, bacteremia, and more pronounced tissue damage and inflammation compared to the findings for mice infected with a single species, despite having a similar bacterial burden within the urinary tract. The presence of P. stuartii, regardless of urease production by this organism, was sufficient to enhance P. mirabilis urease activity and increase disease severity, and enhanced urease activity was the predominant factor driving tissue damage and the dissemination of both organisms to the bloodstream during coinfection. These findings were largely recapitulated in the CAUTI model. Other uropathogens also enhanced P. mirabilis urease activity in vitro, including recent clinical isolates of Escherichia coli, Enterococcus faecalis, Klebsiella pneumoniae, and Pseudomonas aeruginosa We therefore conclude that the underlying mechanism of enhanced urease activity may represent a widespread target for limiting the detrimental consequences of polymicrobial catheter colonization, particularly by P. mirabilis and other urease-positive bacteria.
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http://dx.doi.org/10.1128/IAI.00808-16DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC5278182PMC
February 2017

Regulation and function of bone morphogenetic protein signaling in colonic injury and inflammation.

Am J Physiol Gastrointest Liver Physiol 2017 01 17;312(1):G24-G33. Epub 2016 Nov 17.

Department of Internal Medicine, University of Michigan Medical Center, Ann Arbor, Michigan;

The bone morphogenetic proteins (BMPs) regulate gastrointestinal homeostasis. We investigated the expression of BMP-4 and the localization and function of BMP signaling during colonic injury and inflammation. Mice expressing the β-galactosidase (β-gal) gene under the control of a BMP-responsive element (BRE), BMP-4-β-gal/ mice, and animals generated by crossing villin-Cre mice to mice with floxed alleles of BMP receptor 1A (villin-Cre;Bmpr1a) were treated with dextran sodium sulfate (DSS) to induce colonic injury and inflammation. Expression of BMP-4, β-gal, BMPR1A, IL-8, α-smooth muscle actin, and phosphorylated Smad1, -5, and -8 was assessed by X-Gal staining, quantitative RT-PCR, and immunohistochemistry. Morphology of the colonic mucosa was examined by staining with hematoxylin and eosin. The effect of IFN-γ, TNF-α, IL-1β, and IL-6 on BMP-4 mRNA expression was investigated in human intestinal fibroblasts, whereas that of BMP-4 on IL-8 was assessed in human colonic organoids. BMP-4 was localized in α-smooth muscle actin-positive mesenchymal cells while the majority of BMP-generated signals targeted the epithelium. DSS caused injury and inflammation leading to reduced expression of BMP-4 and of BMPR1A mRNAs, and to decreased BMP signaling. Deletion of BMPR1A enhanced colonic inflammation and damage. Administration of anti-TNF-α antibodies to DSS-treated mice ameliorated colonic inflammation and increased the expression of BMP-4 and BMPR1A mRNAs. TNF-α and IL-1β inhibited both basal and IFN-γ-stimulated BMP-4 expression, whereas IL-6 had no effect. BMP-4 reduced TNF-α-stimulated IL-8 mRNA expressor IL-8 mRNA expression in the organoids. Inflammation and injury inhibit BMP-4 expression and signaling, leading to enhanced colonic damage and inflammation. These observations underscore the importance of BMP signaling in the regulation of intestinal inflammation and homeostasis.

New & Noteworthy: In this study we report a series of novel observations that underscore the importance of bone morphogenetic protein (BMP) signaling in the regulation of colonic homeostasis during the development of injury and inflammation. In particular, we present evidence that BMP signaling mitigates the response of the colonic epithelium to injury and inflammation and that cytokines, such as TNF-α and IL-1β, inhibit the expression of BMP-4.
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http://dx.doi.org/10.1152/ajpgi.00169.2016DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC5283904PMC
January 2017

Siderophore vaccine conjugates protect against uropathogenic Escherichia coli urinary tract infection.

Proc Natl Acad Sci U S A 2016 11 7;113(47):13468-13473. Epub 2016 Nov 7.

Department of Microbiology and Immunology, University of Michigan Medical School, Ann Arbor, MI 48109

Uropathogenic Escherichia coli (UPEC) is the primary cause of uncomplicated urinary tract infections (UTIs). Whereas most infections are isolated cases, 1 in 40 women experience recurrent UTIs. The rise in antibiotic resistance has complicated the management of chronic UTIs and necessitates new preventative strategies. Currently, no UTI vaccines are approved for use in the United States, and the development of a highly effective vaccine remains elusive. Here, we have pursued a strategy for eliciting protective immunity by vaccinating with small molecules required for pathogenesis, rather than proteins or peptides. Small iron-chelating molecules called siderophores were selected as antigens to vaccinate against UTI for this vaccine strategy. These pathogen-associated stealth siderophores evade host immune defenses and enhance bacterial virulence. Previous animal studies revealed that vaccination with siderophore receptor proteins protects against UTI. The poor solubility of these integral outer-membrane proteins in aqueous solutions limits their practical utility. Because their cognate siderophores are water soluble, we hypothesized that these bacterial-derived small molecules are prime vaccine candidates. To test this hypothesis, we immunized mice with siderophores conjugated to an immunogenic carrier protein. The siderophore-protein conjugates elicited an adaptive immune response that targeted bacterial stealth siderophores and protected against UTI. Our study has identified additional antigens suitable for a multicomponent UTI vaccine and highlights the potential use of bacterial-derived small molecules as antigens in vaccine therapies.
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http://dx.doi.org/10.1073/pnas.1606324113DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC5127358PMC
November 2016

Schlafen 4-expressing myeloid-derived suppressor cells are induced during murine gastric metaplasia.

J Clin Invest 2016 08 18;126(8):2867-80. Epub 2016 Jul 18.

Chronic Helicobacter pylori infection triggers neoplastic transformation of the gastric mucosa in a small subset of patients, but the risk factors that induce progression to gastric metaplasia have not been identified. Prior to cancer development, the oxyntic gastric glands atrophy and are replaced by metaplastic cells in response to chronic gastritis. Previously, we identified schlafen 4 (Slfn4) as a GLI1 target gene and myeloid differentiation factor that correlates with spasmolytic polypeptide-expressing metaplasia (SPEM) in mice. Here, we tested the hypothesis that migration of SLFN4-expressing cells from the bone marrow to peripheral organs predicts preneoplastic changes in the gastric microenvironment. Lineage tracing in Helicobacter-infected Slfn4 reporter mice revealed that SLFN4+ cells migrated to the stomach, where they exhibited myeloid-derived suppressor cell (MDSC) markers and acquired the ability to inhibit T cell proliferation. SLFN4+ MDSCs were not observed in infected GLI1-deficient mice. Overexpression of sonic hedgehog ligand (SHH) in infected WT mice accelerated the appearance of SLFN4+ MDSCs in the gastric corpus. Similarly, in the stomachs of H. pylori-infected patients, the human SLFN4 ortholog SLFN12L colocalized to cells that expressed MDSC surface markers CD15+CD33+HLA-DRlo. Together, these results indicate that SLFN4 marks a GLI1-dependent population of MDSCs that predict a shift in the gastric mucosa to a metaplastic phenotype.
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http://dx.doi.org/10.1172/JCI82529DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC4966326PMC
August 2016

Spontaneous Dilated Cardiomyopathy and Right-Sided Heart Failure as a Differential Diagnosis for Hepatosis Dietetica in a Production Pig.

Comp Med 2015 Aug;65(4):327-32

Unit for Laboratory Animal Medicine, In-Vivo Animal Core, University of Michigan Medical School, Ann Arbor, Michigan, USA.

An experimentally naïve 37.7-kg Yorkshire-crossbred gilt died unexpectedly 2 d after arrival. Necropsy revealed severe dilated cardiomyopathy characterized grossly by markedly dilated ventricles and thinned ventricular walls and interventricular septum. Histologically there was multifocal myofiber attenuation and patchy loss of myofiber cross striations. The liver contained submassive to massive, diffuse hepatic centrilobular hemorrhage and degeneration. These lesions supported a diagnosis of dilated cardiomyopathy with right heart failure and secondary hepatic degeneration due to marked acute passive congestion. To our knowledge, this case is the first report of spontaneous dilated cardiomyopathy in swine and represents a potential diagnostic challenge regarding the differentiation of the cardiac-associated liver lesion from hepatosis dietetica. The diagnosis of dilated cardiomyopathy and right-sided heart failure was supported by the character of the hepatic lesion, absence of typical gross or histologic lesions of mulberry heart disease, and normal selenium levels.
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http://www.ncbi.nlm.nih.gov/pmc/articles/PMC4549678PMC
August 2015

Regulation of gastric epithelial cell homeostasis by gastrin and bone morphogenetic protein signaling.

Physiol Rep 2015 Aug;3(8)

Laboratory Animal Medicine Unit, University of Michigan Medical Center, Ann Arbor, Michigan.

We reported that transgenic expression of the bone morphogenetic protein (BMP) signaling inhibitor noggin in the mouse stomach, leads to parietal-cell (PC) loss, expansion of transitional cells expressing markers of both mucus neck and zymogenic lineages, and to activation of proliferative mechanisms. Because these cellular changes were associated with increased levels of the hormone gastrin, we investigated if gastrin mediates the expression of the phenotypic changes of the noggin transgenic mice (NogTG mice). Three-month-old NogTG mice were crossed to gastrin-deficient (GasKO mice) to generate NogTG;GasKO mice. Morphology of the corpus of wild type, NogTG, GasKO, and NogTG;GasKO mice was analyzed by H&E staining. Distribution of PCs and zymogenic cells (ZCs) was analyzed by immunostaining for the H(+)/K(+)-ATPase and intrinsic factor (IF). Expression of the H(+)/K(+)-ATPase and IF genes and proteins were measured by QRT-PCR and western blots. Cell proliferation was assessed by immunostaining for proliferating cell nuclear antigen. The corpus of the NogTG;GasKO mice displayed a marked reduction in the number of PCs and ZCs in comparison to NogTG mice. Further, cellular proliferation was significantly lower in NogTG;GasKO mice, than in the NogTG mice. Thus, gastrin mediates the increase in gastric epithelial cell proliferation induced by inhibition of BMP signaling in vivo. Moreover, gastrin and BMP signaling exert cooperative effects on the maturation and differentiation of both the zymogenic and PC lineages. These findings contribute to a better understanding of the factors involved in the control of gastric epithelial cell homeostasis.
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http://dx.doi.org/10.14814/phy2.12501DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC4562585PMC
August 2015

Humanized microbiota mice as a model of recurrent Clostridium difficile disease.

Microbiome 2015 Aug 20;3:35. Epub 2015 Aug 20.

Baylor College of Medicine, Department of Molecular Virology and Microbiology, Alkek Center for Metagenomics and Microbiome Research, Houston, TX, USA.

Background: Clostridium difficile disease is the leading antibiotic-associated cause of diarrhea and nosocomial acquired infection in the western world. The per annum burden in the USA alone amounts to 250,000 cases with 14,000 ascribed deaths and medical costs in excess of a billion dollars. Novel models for the study of C. difficile infection are therefore pertinent.

Results: Germ free C57BL/6 mice gavaged with a healthy human fecal microbiota maintained a stable "humanized" microbiota over multiple generations when housed under specific pathogen-free (SPF) conditions. As with mice containing a conventional microbiota, treatment with a five-antibiotic cocktail followed by a single dose of clindamycin renders the animals susceptible to C. difficile infection (CDI). Interestingly, after recovery from the initial CDI infection, a single intraperitoneal injection of clindamycin is sufficient to induce CDI relapse. Relapse of CDI can be induced up to 35 days postinfection after recovery from the initial infection, and multiple episodes of relapse can be induced.

Conclusions: This model enables the study of recurrent C. difficile disease in a host containing a human-derived microbiota. Probiotic treatments using human-derived microbes, either prophylactic or curative, can be tested within the model. The identification and testing of human-derived microbial communities within a humanized microbiota mouse model may enable a higher rate of successful transfer of bacteria-based treatments from the lab to human patients due to the microbes involved initiating from, and being adapted to, the human GI tract.
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http://dx.doi.org/10.1186/s40168-015-0097-2DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC4546040PMC
August 2015

Increased Expression of DUOX2 Is an Epithelial Response to Mucosal Dysbiosis Required for Immune Homeostasis in Mouse Intestine.

Gastroenterology 2015 Dec 7;149(7):1849-59. Epub 2015 Aug 7.

Division of Gastroenterology, Department of Internal Medicine, University of Michigan Medical School, Ann Arbor, Michigan. Electronic address:

Background & Aims: Dual oxidase 2 (DUOX2), a hydrogen-peroxide generator at the apical membrane of gastrointestinal epithelia, is up-regulated in patients with inflammatory bowel disease (IBD) before the onset of inflammation, but little is known about its effects. We investigated the role of DUOX2 in maintaining mucosal immune homeostasis in mice.

Methods: We analyzed the regulation of DUOX2 in intestinal tissues of germ-free vs conventional mice, mice given antibiotics or colonized with only segmented filamentous bacteria, mice associated with human microbiota, and mice with deficiencies in interleukin (IL) 23 and IL22 signaling. We performed 16S ribosomal RNA gene quantitative polymerase chain reaction of intestinal mucosa and mesenteric lymph nodes of Duoxa(-/-) mice that lack functional DUOX enzymes. Genes differentially expressed in Duoxa(-/-) mice compared with co-housed wild-type littermates were correlated with gene expression changes in early-stage IBD using gene set enrichment analysis.

Results: Colonization of mice with segmented filamentous bacteria up-regulated intestinal expression of DUOX2. DUOX2 regulated redox signaling within mucosa-associated microbes and restricted bacterial access to lymphatic tissues of the mice, thereby reducing microbiota-induced immune responses. Induction of Duox2 transcription by microbial colonization did not require the mucosal cytokines IL17 or IL22, although IL22 increased expression of Duox2. Dysbiotic, but not healthy human microbiota, activated a DUOX2 response in recipient germ-free mice that corresponded to abnormal colonization of the mucosa with distinct populations of microbes. In Duoxa(-/-) mice, abnormalities in ileal mucosal gene expression at homeostasis recapitulated those in patients with mucosal dysbiosis.

Conclusions: DUOX2 regulates interactions between the intestinal microbiota and the mucosa to maintain immune homeostasis in mice. Mucosal dysbiosis leads to increased expression of DUOX2, which might be a marker of perturbed mucosal homeostasis in patients with early-stage IBD.
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http://dx.doi.org/10.1053/j.gastro.2015.07.062DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC4663159PMC
December 2015

Coculture of Escherichia coli O157:H7 with a Nonpathogenic E. coli Strain Increases Toxin Production and Virulence in a Germfree Mouse Model.

Infect Immun 2015 Nov 10;83(11):4185-93. Epub 2015 Aug 10.

Department of Food Science, Penn State University, University Park, Pennsylvania, USA Center for Immunology and Infectious Disease, Penn State University, University Park, Pennsylvania, USA

Escherichia coli O157:H7 is a notorious foodborne pathogen due to its low infectious dose and the disease symptoms it causes, which include bloody diarrhea and severe abdominal cramps. In some cases, the disease progresses to hemorrhagic colitis (HC) and hemolytic uremic syndrome (HUS), due to the expression of one or more Shiga toxins (Stx). Isoforms of Stx, including Stx2a, are encoded within temperate prophages. In the presence of certain antibiotics, phage induction occurs, which also increases the expression of toxin genes. Additionally, increased Stx2 accumulation has been reported when O157:H7 was cocultured with phage-susceptible nonpathogenic E. coli. This study characterized an E. coli O157:H7 strain, designated PA2, that belongs to the hypervirulent clade 8 cluster. Stx2a levels after ciprofloxacin induction were lower for PA2 than for the prototypical outbreak strains Sakai and EDL933. However, during coculture with the nonpathogenic strain E. coli C600, PA2 produced Stx2a levels that were 2- to 12-fold higher than those observed during coculture with EDL933 and Sakai, respectively. Germfree mice cocolonized by PA2 and C600 showed greater kidney damage, increased Stx2a accumulation in feces, and more visible signs of disease than mice given PA2 or C600 alone. These data suggest one mechanism by which microorganisms associated with the colonic microbiota could enhance the virulence of E. coli O157:H7, particularly a subset of clade 8 strains.
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http://dx.doi.org/10.1128/IAI.00663-15DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC4598395PMC
November 2015

Use of Femoral Head and Neck Ostectomy and Physical Therapy to Manage Osteoarthritis in a Rhesus Macaque (Macaca mulatta).

Comp Med 2015 Jun;65(3):260-5

University of Michigan, Unit for Laboratory Animal Medicine. Ann Arbor, Michigan, USA.

Osteoarthritis is associated with pain and immobility in both humans and animals. However, available resources for osteoarthritis management in captive NHP are limited. This case report describes a novel management strategy for a 10-y-old male macaque with unilateral hindlimb lameness, prominent muscle wasting, and severely limited range of motion. Radiographs of the affected limb showed lytic lesions of the femoral head. To relieve pain and improve mobility, femoral head and neck ostectomy (FHO) was performed, and multiple pharmacotherapies were initiated. The macaque also received a unique method of physical therapy that required no sedation, acted as enrichment, and was implemented by using a conventional caging system. The response to therapy was monitored by measuring thigh circumference in the operated and nonoperated limbs, which demonstrated improvement in both legs. The unique physical therapy in conjunction with surgery and pharmacotherapy benefited the macaque with osteoarthritis by reducing discomfort and improving mobility.
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http://www.ncbi.nlm.nih.gov/pmc/articles/PMC4485634PMC
June 2015

How free of germs is germ-free? Detection of bacterial contamination in a germ free mouse unit.

Gut Microbes 2015 Jul 27;6(4):225-33. Epub 2015 May 27.

a Department of Microbiology and Immunology ; University of Michigan Medical School ; Ann Arbor , MI USA.

Management of germ free animals has changed little since the beginning of the 20th century. The current upswing in their use, however, has led to interest in improved methods of screening and housing. Traditionally, germ free colonies are screened for bacterial colonization by culture and examination of Gram stained fecal samples, but some investigators have reported using PCR-based methods of microbial detection, presumably because of perceived increased sensitivity. The accuracy and detection limit for traditional compared to PCR-based screening assays are not known. The purpose of this study was to determine the limit of detection of bacterial contamination of mouse feces by aerobic and anaerobic culture, Gram stain, and qPCR, and to compare the accuracy of these tests in the context of a working germ free mouse colony. We found that the limit of detection for qPCR (approximately 10(5) cfu/g of feces) was lower than for Gram stain (approximately 10(9) cfu/g), but that all 3 assays were of similar accuracy. Bacterial culture was the most sensitive, but the least specific, and qPCR was the least sensitive and most specific. Gram stain but not qPCR detected heat-killed bacteria, indicating that bacteria in autoclaved diet are unlikely to represent a potential confounding factor for PCR screening. We conclude that as a practical matter, bacterial culture and Gram stain are adequate for screening germ free mouse colonies for bacterial contaminants, but that should low numbers of unculturable bacteria be present, they would not be detected with any of the currently available means.
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http://dx.doi.org/10.1080/19490976.2015.1054596DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC4615677PMC
July 2015

Animal Model Reveals Potential Waterborne Transmission of Helicobacter pylori Infection.

Helicobacter 2015 Oct 9;20(5):326-33. Epub 2015 Feb 9.

Department of Environmental Health Sciences, University of Michigan, Ann Arbor, MI, USA.

Background: Helicobacter pylori infection has been consistently associated with lack of access to clean water and proper sanitation, but no studies have demonstrated that the transmission of H. pylori can occur from drinking contaminated water. In this study, we used a laboratory mouse model to test whether waterborne H. pylori could cause gastric infection.

Materials And Methods: Groups of immunocompetent C57/BL6 Helicobacter-free mice were exposed to static concentrations (1.29 × 10(5), 10(6), 10(7), 10(8), and 10(9) CFU/L) of H. pylori in their drinking water for 4 weeks. One group of Helicobacter-free mice was exposed to uncontaminated water as a negative control. H. pylori morphology changes in water were examined using microscopy Live/Dead staining. Following exposure, H. pylori infection and inflammation status in the stomach were evaluated using quantitative culture, PCR, the rapid urease test, and histology.

Results: None of the mice in the negative control or 10(5) groups were infected. One of 20 cages (one of 40 mice) of the 10(6) group, three of 19 cages (four of 38 mice) of the 10(7) CFU/L group, 19 of 20 cages (33 of 40 mice) of the 10(8) group, and 20 of 20 cages (39 of 40 mice) of the 10(9) CFU/L group were infected. Infected mice had significantly higher gastric inflammation than uninfected mice (27.86% higher inflammation, p < .0001).

Conclusions: We offer proof that H. pylori in water is infectious in mice, suggesting that humans drinking contaminated water may be at risk of contracting H. pylori infection. Much work needs to be performed to better understand the risk of infection from drinking H. pylori-contaminated water.
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http://dx.doi.org/10.1111/hel.12216DOI Listing
October 2015

Anti-inflammatory activity of bone morphogenetic protein signaling pathways in stomachs of mice.

Gastroenterology 2014 Aug 18;147(2):396-406.e7. Epub 2014 Apr 18.

Department of Internal Medicine, University of Michigan Medical Center, Ann Arbor, Michigan. Electronic address:

Background & Aims: Bone morphogenetic protein (BMP)4 is a mesenchymal peptide that regulates cells of the gastric epithelium. We investigated whether BMP signaling pathways affect gastric inflammation after bacterial infection of mice.

Methods: We studied transgenic mice that express either the BMP inhibitor noggin or the β- galactosidase gene under the control of a BMP-responsive element and BMP4(βgal/+) mice. Gastric inflammation was induced by infection of mice with either Helicobacter pylori or Helicobacter felis. Eight to 12 weeks after inoculation, gastric tissue samples were collected and immunohistochemical, quantitative, reverse-transcription polymerase chain reaction and immunoblot analyses were performed. We used enzyme-linked immunosorbent assays to measure cytokine levels in supernatants from cultures of mouse splenocytes and dendritic cells, as well as from human gastric epithelial cells (AGS cell line). We also measured the effects of BMP-2, BMP-4, BMP-7, and the BMP inhibitor LDN-193189 on the expression of interleukin (IL)8 messenger RNA by AGS cells and primary cultures of canine parietal and mucus cells. The effect of BMP-4 on NFkB activation in parietal and AGS cells was examined by immunoblot and luciferase assays.

Results: Transgenic expression of noggin in mice increased H pylori- or H felis-induced inflammation and epithelial cell proliferation, accelerated the development of dysplasia, and increased expression of the signal transducer and activator of transcription 3 and activation-induced cytidine deaminase. BMP-4 was expressed in mesenchymal cells that expressed α-smooth muscle actin and activated BMP signaling pathways in the gastric epithelium. Neither BMP-4 expression nor BMP signaling were detected in immune cells of C57BL/6, BRE-β-galactosidase, or BMP-4(βgal/+) mice. Incubation of dendritic cells or splenocytes with BMP-4 did not affect lipopolysaccharide-stimulated production of cytokines. BMP-4, BMP-2, and BMP-7 inhibited basal and tumor necrosis factor α-stimulated expression of IL8 in canine gastric epithelial cells. LDN-193189 prevented BMP4-mediated inhibition of basal and tumor necrosis factor α-stimulated expression of IL8 in AGS cells. BMP-4 had no effect on TNFα-stimulated phosphorylation and degradation of IκBα, or on TNFα induction of a NFκβ reporter gene.

Conclusions: BMP signaling reduces inflammation and inhibits dysplastic changes in the gastric mucosa after infection of mice with H pylori or H felis.
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http://dx.doi.org/10.1053/j.gastro.2014.04.015DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC4197994PMC
August 2014

The effects of intestinal microbial community structure on disease manifestation in IL-10-/- mice infected with Helicobacter hepaticus.

Microbiome 2013 May 10;1(1):15. Epub 2013 May 10.

Department of Internal Medicine/Infectious Diseases Division, University of Michigan Medical School, Ann Arbor, MI, 48109, USA.

Background: The aberrant inflammation that is the hallmark of the inflammatory bowel diseases (IBD) is associated with several factors, including changes in the intestinal microbiota. Here, we confirmed that an intestinal microbiota is needed for development of typhlocolitis in Helicobacter hepaticus infected IL-10-/- C57BL/6 mice, and investigated the role of the microbiota in modulating disease.

Results: We altered the murine microbiota by treatment with the antibiotics vancomycin or cefoperazone prior to H. hepaticus infection. Through surveys of the 16S rRNA encoding-gene, analyses of histology and changes in expression of host mediators, we correlated alterations in the microbiota with host responses. We found that resident microbes are essential for initiation of disease, as animals mono-associated with H. hepaticus did not develop colitis. Despite the requirement for an indigenous microbiota for the initiation of disease, the severity of disease was independent of antibiotic-induced changes in the microbial community structure. Despite differences in the expression of host inflammatory mediators associated with shifts in the microbiota, H. hepaticus infection led to similar histopathologic lesions in microbial communities exposed to either cefoperazone or vancomycin.

Conclusion: In conclusion, we demonstrate that colitis due to H. hepaticus infection can be initiated and progress in the presence of several different microbial communities. Furthermore, H. hepaticus is the main driver of inflammation in this model, while the specific structure of the microbiota may modulate the host pathways that lead to chronic inflammation.
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http://dx.doi.org/10.1186/2049-2618-1-15DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC3971628PMC
May 2013

Gut microbiota protects against gastrointestinal tumorigenesis caused by epithelial injury.

Cancer Res 2013 Dec 28;73(24):7199-210. Epub 2013 Oct 28.

Authors' Affiliations: Division of Hematology and Oncology, Department of Internal Medicine, Department of Pathology, Comprehensive Cancer Center, Unit for Laboratory Animal Medicine, and Department of Microbiology and Immunology, University of Michigan Medical School, University of Michigan, Ann Arbor, Michigan.

Inflammation is a critical player in the development of both colitis-associated and sporadic colon cancers. Several studies suggest that the microbiota contribute to inflammation and tumorigenesis; however, studies to understand the role of the microbiota in colon tumor development in germ-free (GF) mice are limited. We therefore studied the effects of the microbiota on the development of inflammation and tumors in GF and conventionally raised specific pathogen-free (SPF) mice treated with azoxymethane (AOM) and dextran sulfate sodium (DSS). We discovered that GF mice developed significantly more and larger tumors compared with that in SPF mice after AOM and DSS treatment despite the lack of early acute inflammation in response to chemically induced injury by DSS. Although the extent of intestinal epithelial damage and apoptosis was not significantly different in GF and SPF mice, there was a delay in intestinal epithelial repair to DSS-induced injury in GF mice resulting in a late onset of proinflammatory and protumorigenic responses and increased epithelial proliferation and microadenoma formation. Recolonization of GF mice with commensal bacteria or administration of lipopolysaccharide reduced tumorigenesis. Thus, although commensal bacteria are capable of driving chronic inflammation and tumorigenesis, the gut microbiota also have important roles in limiting chemically induced injury and proliferative responses that lead to tumor development.
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http://dx.doi.org/10.1158/0008-5472.CAN-13-0827DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC3883499PMC
December 2013

TLR2 mediates Helicobacter pylori-induced tolerogenic immune response in mice.

PLoS One 2013 13;8(9):e74595. Epub 2013 Sep 13.

Department of Pharmacology, School of Medicine, Shandong University, Jinan, Shandong, China ; Division of Gastroenterology, Department of Internal Medicine, University of Michigan Health System, Ann Arbor, Michigan, United States of America.

We have shown that Helicobacter pylori induces tolerogenic programming of dendritic cells and inhibits the host immune response. Toll-like receptors (TLRs) represent a class of transmembrane pattern recognition receptors essential for microbial recognition and control of the innate immune response. In this study, we examined the role of TLRs in mediating H. pylori tolerogenic programming of dendritic cells and their impact on anti-H. pylori immunity using C57BL/6 wild-type and TLR2-knockout (TLR2KO) mice. We analyzed the response of TLR2KO bone marrow-derived dendritic cells (BMDCs) to H. pylori SS1 stimulation and the outcome of chronic H. pylori infection in TLR2KO mice. We showed that H. pylori-stimulated BMDCs upregulated the expression of TLR2, but not TLR4, TLR5, or TLR9. H. pylori-stimulated BMDCs from TLRKO mice induced lower Treg and Th17 responses, but a higher IFN-γ response compared to H. pylori-stimulated BMDCs from wild-type mice. In vivo analyses following an H. pylori infection of 2 months duration showed a lower degree of gastric H. pylori colonization in TLR2KO mice and more severe gastric immunopathology compared to WT mice. The gastric mucosa of the infected TLR2KO mice showed a lower mRNA expression of Foxp3, IL-10, and IL-17A, but higher expression of IFN-γ compared to the gastric mRNA expression in infected wild-type mice. Moreover, the H. pylori-specific Th1 response was higher and the Treg and Th17 responses were lower in the spleens of infected TLR2KO mice compared to infected WT mice. Our data indicate that H. pylori mediates immune tolerance through TLR2-derived signals and inhibits Th1 immunity, thus evading host defense. TLR2 may be an important target in the modulation of the host response to H. pylori.
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http://journals.plos.org/plosone/article?id=10.1371/journal.pone.0074595PLOS
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC3772856PMC
June 2014

Prophage induction is enhanced and required for renal disease and lethality in an EHEC mouse model.

PLoS Pathog 2013 Mar 28;9(3):e1003236. Epub 2013 Mar 28.

Department of Microbiology and Immunology, University of Michigan, Ann Arbor, Michigan, United States of America.

Enterohemorrhagic Escherichia coli (EHEC), particularly serotype O157:H7, causes hemorrhagic colitis, hemolytic uremic syndrome, and even death. In vitro studies showed that Shiga toxin 2 (Stx2), the primary virulence factor expressed by EDL933 (an O157:H7 strain), is encoded by the 933W prophage. And the bacterial subpopulation in which the 933W prophage is induced is the producer of Stx2. Using the germ-free mouse, we show the essential role 933W induction plays in the virulence of EDL933 infection. An EDL933 derivative with a single mutation in its 933W prophage, resulting specifically in that phage being uninducible, colonizes the intestines, but fails to cause any of the pathological changes seen with the parent strain. Hence, induction of the 933W prophage is the primary event leading to disease from EDL933 infection. We constructed a derivative of EDL933, SIVET, with a biosensor that specifically measures induction of the 933W prophage. Using this biosensor to measure 933W induction in germ-free mice, we found an increase three logs greater than was expected from in vitro results. Since the induced population produces and releases Stx2, this result indicates that an activity in the intestine increases Stx2 production.
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http://dx.doi.org/10.1371/journal.ppat.1003236DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC3610611PMC
March 2013