Diet-driven differential response of Akkermansia muciniphila modulates pathogen susceptibility

The erosion of the colonic mucus layer by a dietary fiber-deprived gut microbiota results in heightened susceptibility to an attaching and effacing pathogen, Citrobacter rodentium. Nevertheless, the questions of whether and how specific mucolytic bacteria aid in the increased pathogen susceptibility remain unexplored. Here, we leverage a functionally characterized, 14-member synthetic human microbiota in gnotobiotic mice to deduce which bacteria and functions are responsible for the pathogen susceptibility. Using strain dropouts of mucolytic bacteria from the community, we show that Akkermansia muciniphila renders the host more vulnerable to the mucosal pathogen during fiber deprivation. However, the presence of A. muciniphila reduces pathogen load on a fiber-sufficient diet, highlighting the context-dependent beneficial effects of this mucin specialist. The enhanced pathogen susceptibility is not owing to altered host immune or pathogen responses, but is driven by a combination of increased mucus penetrability and altered activities of A. muciniphila and other community members. Our study provides novel insights into the mechanisms of how discrete functional responses of the same mucolytic bacterium either resist or enhance enteric pathogen susceptibility.

Opposing diet, microbiome, and metabolite mechanisms regulate inflammatory bowel disease in a genetically susceptible host

Inflammatory bowel diseases (IBDs) are chronic conditions characterized by periods of spontaneous intestinal inflammation and are increasing in industrialized populations. Combined with host genetics, diet and gut bacteria are thought to contribute prominently to IBDs, but mechanisms are still emerging. In mice lacking the IBD-associated cytokine, interleukin-10, we show that a fiber-deprived gut microbiota promotes the deterioration of colonic mucus, leading to lethal colitis. Inflammation starts with the expansion of natural killer cells and altered immunoglobulin-A coating of some bacteria. Lethal colitis is then driven by Th1 immune responses to increased activities of mucin-degrading bacteria that cause inflammation first in regions with thinner mucus. A fiber-free exclusive enteral nutrition diet also induces mucus erosion but inhibits inflammation by simultaneously increasing an anti-inflammatory bacterial metabolite, isobutyrate. Our findings underscore the importance of focusing on microbial functions-not taxa-contributing to IBDs and that some diet-mediated functions can oppose those that promote disease.

Diet-driven differential response of Akkermansia muciniphila modulates pathogen susceptibility

The erosion of the colonic mucus layer by a dietary fiber-deprived gut microbiota results in heightened susceptibility to an attaching and effacing pathogen, Citrobacter rodentium. Nevertheless, the questions of whether and how specific mucolytic bacteria aid in the increased pathogen susceptibility remain unexplored. Here, we leverage a functionally characterized, 14-member synthetic human microbiota in gnotobiotic mice to deduce which bacteria and functions are responsible for the pathogen susceptibility. Using strain dropouts of mucolytic bacteria from the community, we show that Akkermansia muciniphila renders the host more vulnerable to the mucosal pathogen during fiber deprivation. However, the presence of A. muciniphila reduces pathogen load on a fiber-sufficient diet, highlighting the context-dependent beneficial effects of this mucin specialist. The enhanced pathogen susceptibility is not owing to altered host immune or pathogen responses, but is driven by a combination of increased mucus penetrability and altered activities of A. muciniphila and other community members. Our study provides novel insights into the mechanisms of how discrete functional responses of the same mucolytic bacterium either resist or enhance enteric pathogen susceptibility.

Unravelling specific diet and gut microbial contributions to inflammatory bowel disease

Inflammatory bowel disease (IBD) is a chronic condition characterized by periods of spontaneous intestinal inflammation and is increasing in industrialized populations. Combined with host genetic predisposition, diet and gut bacteria are thought to be prominent features contributing to IBD, but little is known about the precise mechanisms involved. Here, we show that low dietary fiber promotes bacterial erosion of protective colonic mucus, leading to lethal colitis in mice lacking the IBD-associated cytokine, interleukin-10. Diet-induced inflammation is driven by mucin-degrading bacteria-mediated Th1 immune responses and is preceded by expansion of natural killer T cells and reduced immunoglobulin A coating of some bacteria. Surprisingly, an exclusive enteral nutrition diet, also lacking dietary fiber, reduced disease by increasing bacterial production of isobutyrate, which is dependent on the presence of a specific bacterial species, Eubacterium rectale. Our results illuminate a mechanistic framework using gnotobiotic mice to unravel the complex web of diet, host and microbial factors that influence IBD.

A steamed broccoli sprout diet preparation that reduces colitis via the gut microbiota

Sulforaphane is a bioactive metabolite with anti-inflammatory activity and is derived from the glucosinolate glucoraphanin, which is highly abundant in broccoli sprouts. However, due to its inherent instability its use as a therapeutic against inflammatory diseases has been limited. There are few studies to investigate a whole food approach to increase sulforaphane levels with therapeutic effect and reduce inflammation. In the current study, using a mouse model of inflammatory bowel disease, we investigated the ability of steamed broccoli sprouts to ameliorate colitis and the role of the gut microbiota in mediating any effects. We observed that despite inactivation of the plant myrosinase enzyme responsible for the generation of sulforaphane via steaming, measurable levels of sulforaphane were detectable in the colon tissue and feces of mice after ingestion of steamed broccoli sprouts. In addition, this preparation of broccoli sprouts was also capable of reducing chemically-induced colitis. This protective effect was dependent on the presence of an intact microbiota, highlighting an important role for the gut microbiota in the metabolism of cruciferous vegetables to generate bioactive metabolites and promote their anti-inflammatory effects.

Prototype endoscopic photoacoustic-ultrasound balloon catheter for characterizing intestinal obstruction

In our previous studies, we have demonstrated the feasibility of characterizing intestinal inflammation and fibrosis using endoscopic photoacoustic imaging. Purposed at te clinical translation of the imaging technology, we developed a photoacoustic/ultrasound imaging probe by integrating a miniaturized ultrasound array and an angle-tipped optical fiber in a hydrostatic balloon catheter. When collapsed, the catheter probe may potentially be compatible with a clinical ileo-colonoscope. In addition, the flexible surface of the hydrostatic balloon allows for acoustic coupling at the uneven surfaces of the gas-filled intestine. Tissue phantom studies show that the catheter probe possesses an imaging penetration of at least 12 mm. Experiments with a rabbit model in vivo validated the probe in differentiating normal, acute and chronic conditions in intestinal obstruction.

Effect of ABT-263 on Intestinal Fibrosis in Human Myofibroblasts, Human Intestinal Organoids, and the Mouse Salmonella typhimurium Model

BACKGROUND

Intestinal fibrosis and subsequent intestinal obstruction are common complications of Crohn's disease (CD). Current therapeutics combat inflammation, but no pharmacological therapy exists for fibrostenotic disease. Pathological persistence of activated intestinal myofibroblasts is a key driver of fibrosis in CD. In other organ systems, BH-3 mimetic drugs that affect Bcl-2 apoptotic pathways induce apoptosis in activated myofibroblasts and reduce fibrogenic gene expression, thereby reducing fibrosis.

METHODS

We evaluated the proapoptotic and antifibrotic efficacy of several classes of BH-3 mimetics in 2 in vitro fibrogenesis models. The candidate molecule, ABT-263, was advanced to a 3-dimensional human intestinal organoid (HIO) model. Finally, the therapeutic efficacy of ABT-263 was evaluated in the mouse Salmonella typhimurium intestinal fibrosis model.

RESULTS

The BH-3 mimetics induced apoptosis, repressed fibrotic protein expression, and reduced fibrogenic gene expression in normal human intestinal myofibroblasts. The BH-3 mimetics that target Bcl-2 and Bcl-xl demonstrated the greatest efficacy in vitro. The ABT-199 and ABT-263 induced apoptosis and ameliorated fibrogenesis in the in vitro myofibroblast models. In the HIO model, ABT-263 inhibited fibrogenesis and induced apoptosis. In the mouse S. typhimurium model, dose-dependent reduction in macroscopic pathology, histological inflammation, inflammatory and fibrotic gene expression, and extracellular matrix protein expression indicated ABT-263 may reduce intestinal fibrosis.

CONCLUSIONS

In vitro, the antifibrotic efficacy of BH-3 mimetics identifies the Bcl-2 pathway as a druggable target and BH-3 mimetics as putative therapeutics. Reduction of inflammation and fibrosis in the mouse intestinal fibrosis model by ABT-263 indicates BH-3 mimetics as potential, novel antifibrotic therapeutics for Crohn's disease.

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

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^∆DC 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^∆DC mice onto Rag1KO background to generate TGF-β^∆DC xRag1KO mice.

RESULTS

When stimulated with H. pylori, TGF-β^∆DC 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^∆DC mice developed more severe gastritis and a trend toward more metaplasia compared to TGF-β^fl/fl with increased levels of inflammatory Th1 cytokine mRNA and lower gastric H. felis colonization compared to infected TGF-β^fl/fl mice. In a T cell-deficient background using TGF-β^∆DC 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.

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

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.

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

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.

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

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.

Brexit - Consequences for the UK's Oral Health Workforce?

On Friday, 20 December 2019, after three and a half years of discussion the Parliament of the United Kingdom (UK) voted decisively that this country should leave the European Union (EU). For many of us this was a sad day. However, this political decision has been made and intensive negotiations will now take place between the UK and the EU's negotiating teams to agree the details for the UK's future relationship with the EU. It is still far from clear exactly what the consequences of the resulting deal will be for both parties. A number of previous articles and editorials have speculated on the possible consequences for health and oral health in the UK. Key areas include workforce, research and regulations for medicines and medical and dental equipment. This editorial will consider the implications for the UK's Oral healthcare workforce.

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

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. Proteus mirabilis is one of the most common causes of monomicrobial and polymicrobial CAUTI and frequently cocolonizes with Enterococcus faecalis, Escherichia coli, Providencia stuartii, and Morganella morganiiP. mirabilis 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 P. mirabilis and other uropathogens can enhance P. mirabilis urease activity, resulting in greater disease severity during experimental polymicrobial infection. Our present work reveals that M. morganii acts on P. mirabilis in a contact-independent manner to decrease urease activity. Furthermore, M. morganii actively prevents urease enhancement by E. faecalis, P. stuartii, and E. coli 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.

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

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.

The gut microbiome can contribute to colon tumor susceptibility via an effect on CD8+ T cell responses

There is increasing evidence that colorectal cancer patients have altered gut microbiomes compared to healthy controls, but the mechanisms by which the microbiota contribute to colon carcinogenesis remain to be fully elucidated. Using the azoxymethane (AOM)/dextran sulfate sodium (DSS) mouse model of inflammation-associated colon tumorigenesis, our lab discovered two colonies of specific pathogen free (SPF) C57BL/6J wild type (WT) mice housed in the same mouse room that develop differential tumor burdens. Mice from the “WT1” colony developed five tumors on average while mice from the “WT2” colony developed 15 tumors on average. The increased tumor susceptibility in WT2 mice can be directly attributed to the gut microbiome as germ-free (GF) mice colonized with WT2 bacteria developed more tumors compared to that of GF mice colonized with WT1 bacteria. Additionally, 16S rRNA gene sequencing of fecal bacteria from WT1 and WT2 mice revealed distinct microbiomes with certain bacteria consistently associated with high or low tumor numbers. Furthermore, naïve and acutely-inflamed (day 10 of AOM/DSS) WT2 mice have increased colon lamina propria CD8+ IFNγ+ T cells compared to WT1 mice as measured by flow cytometry. However, in tumor-bearing WT2 mice, there was decreased tumor-infiltrating CD8+ T cells with reduced IFNγ production, possibly due to T cell exhaustion. GF Rag1−/− mice as well as SPF CD8−/− mice inoculated with WT2 gut microbiota developed fewer tumors than SPF WT2 mice, suggesting that the WT2 gut microbiome increases tumor susceptibility, in part, through an effect on CD8+ T cells. Altogether, our data reveal a potential novel role of microbiota in altering colon CD8+ T cell function that ultimately impacts colon cancer risk.

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

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 in vivo. 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 in vivo.

The healthcare system and the provision of oral healthcare in European Union member states. Part 7: Republic of Ireland

The Irish oral healthcare system is a hybrid model with a public/private mix of service provision, predominantly organised on the basis of fee-per-item remuneration. The system is structured around three long standing publicly funded schemes: the Public Dental Service (PDS) for all children and adults with special needs and provided by salaried dentists, the Dental Treatment Services Scheme (DTSS) for low income adults, and the Dental Treatment Benefit Scheme (DTBS) for insured persons, the latter two both provided by private independent dental practitioners. Ireland introduced systemic water fluoridation in 1963 and currently 73% of the population has access to fluoridated water. Ireland currently has a dentist density ratio of 6.1 dentists per 10,000 inhabitants and on average, 43% of the population (30% for those aged 70+ years) visit a dentist annually. In 2014, 83% of expenditure on oral healthcare was from out-of-pocket payments by patients, with less than 1% of overall government expenditure on healthcare allotted to oral healthcare. After the economic downturn of 2008 and the severe recession that followed in Ireland, substantial cutbacks in government expenditure resulted in extensive cuts to the public sector supply of dental services and to the extent of cover provided by the publicly funded schemes. The Department of Health has recognised the major post recessionary challenges facing the Irish health system, not least, significantly reduced budgets and capacity deficits, and acknowledges the need for change in Ireland's health service. In 2014, a three-year project commenced at the Department of Health, to develop a new national oral health policy for Ireland.

The healthcare system and the provision of oral healthcare in European Union member states. Part 8: Italy

In Italy healthcare is provided for all Italian citizens and residents and it is delivered mainly by public providers, with some private or private-public entities. Italy's public healthcare system - the Servizio Sanitario Nazionale (SSN) - is organised by the Ministry of Health and administered on a devolved regional basis. It is financed by general taxation that provides universal coverage, largely free of charge at the point of service. The central government establishes the basic national health benefits package, which must be uniformly provided throughout the country, through services guaranteed under the NHS provision called LEA - (Livelli Essenziali di Assistenza [Essential Level of Assistance]) and allocates national funds to the regions. The regions, through their regional health departments, are responsible for organising, administering and delivering primary, secondary and tertiary healthcare services as well as preventive and health promotion services. Regions are allowed a large degree of autonomy in how they perform this role and regarding decisions about the local structure of the system. Complementary and supplementary private health insurance is also available. However, as in most other Mediterranean European countries, in Italy oral healthcare is mainly provided under private arrangements. The public healthcare system provides only 5-8% of oral healthcare services and this percentage varies from region to region. Oral healthcare is included in the Legislation on Essential levels of care (LEAs) for specific populations such as children, vulnerable people (medically compromised and those on low income) and individuals who need oral healthcare in some urgent/emergency cases. For other people, oral healthcare is generally not covered. Apart from the national benefits package, regions may also carry out their own initiatives autonomously, but must finance these themselves. The number of dentists working in Italy has grown rapidly in the last few years. In December 2014, there were 59,324 practicing dentists with a ratio of one dentist every 1025 inhabitants, about 90,000 dental chair-side assistants, about 26,000 dental technicians and about 4000 dental hygienists. To enrol in an Italian dental school a student must pass a competitive national entrance examination after obtaining a high school leaving certificate. For entry in the 2015-2016 cycle, there were 792 places for dentistry. In comparison with dental schools in other EU member states, the number of dental students per school is low with an average of 20 students per year, per school and a range of 10 to 60. The aims of this paper are to give a brief description of the organisation of healthcare in Italy, to outline the system for the provision of oral healthcare in Italy and to explain and discuss the latest changes.

Looking after the mouth - Evaluation of a pilot for a new approach to training care home carers in Kent, Surrey and Sussex

Objective This pilot study aimed to produce and evaluate training resources and training in oral health care, including oral hygiene, for carers in care homes in Surrey and Medway.Methods During two training days, for carers from these homes, short, interactive presentations were given on a range of topics relevant to oral health care and oral hygiene of older people, followed by practical training. Prior to any training all attendees completed a 39 question questionnaire to establish their baseline knowledge of oral health and hygiene. At the end of the training day they completed an evaluation form. Fourteen weeks later, they were visited at their place of work and completed the same questionnaire again. Differences in responses between baseline and after 14 weeks were statistically tested using the chi-squared test.Results Sixty-six carers attended the training sessions and 44 were followed up 14 weeks later. The results showed an improvement in carer knowledge at follow up. The majority of carers (36/44) spoke English as their first language. They had a mean age of 41 years, 37 were female and 7 male. They had worked as carers for a mean of 10.9 years (range 4 months-34 years). Over 90% stated that the training day fully met or exceeded their requirements and expectations.Conclusions The results indicated improvements in carer knowledge. However, the carers were atypical of carers in general, as they were self-selected and well-motivated. Nevertheless the content of the training day and the questionnaire should inform future work in this area.

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

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^+ve cells during inflammation.

METHODS

The H⁺/K⁺-adenosine triphosphatase β-subunit promoter was used to express the BMP inhibitor noggin (Nog) in the stomach (H⁺/K⁺-Nog mice). Inhibition of BMP signaling in Lgr5 cells was achieved by crossing Lgr5-EGFP-ires-CreERT2 (Lgr5-Cre) mice to mice with floxed alleles of BMP receptor 1A (Lgr5-Cre;Bmpr1a^flox/flox mice). Lgr5/GFP^+ve cells were isolated using flow cytometry. Lineage tracing studies were conducted by crossing Lgr5-Cre mice to mice that express Nog and tdTomato (Lgr5-Cre;H⁺/K⁺-Nog;Rosa26-tdTom). Infection with Helicobacter felis 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. Id1, Bmpr1a, Lgr5, c-Myc, and Cd44 messenger RNAs were measured by quantitative reverse-transcription polymerase chain reaction.

RESULTS

Lgr5-Cre;Bmpr1a^flox/flox mice showed diminished expression of Bmpr1a in Lgr5/GFP^+ve cells. Infection of Lgr5-Cre;Bmpr1a^flox/flox mice with H felis led to enhanced inflammation, increased cell proliferation, parietal cell loss, and to the development of metaplasia and dysplasia. Infected Lgr5-Cre;H⁺/K⁺-Nog;Rosa26-tdTom mice, but not control mice, showed the presence of tomato^+ve 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^+ve cells, which give rise to metaplastic, dysplastic, proliferating lineages that express markers of mucus neck and zymogenic cell differentiation.

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

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.

Variation in methods used to determine national mean DMFT scores for 12-year-old children in European countries

Aim

The aim of this study was to investigate the methods used to identify national mean DMFT scores for 12-year-old children in all the Member States of the European Union and European Economic Area, and in 11 other European countries.

Methods

The most recent national mean DMFT scores were accessed from the World Health Organisation Oral Health CAPP and the Council of European Chief Dental Officers databanks. A literature search was then performed to access the reports of the studies that had produced these DMFT scores, cited on these databanks. The reports were then analysed to determine: the year in which the survey/study that produced the score took place, the year the results were published, the geographical area (national, regional or local) covered, the number of children examined, how many examiners took part, how they were trained and calibrated, and the criteria used for the detection of caries.

Results

Data and information from 43 European countries were accessed. The years when the studies were performed ranged from 1990 to 2014. There were doubts over the representativeness of some samples. A wide range of different methods were used. Examiner training and calibration were very variable both in terms of duration and reported inter and intra-examiner consistency. There were important variations in the criteria employed for the detection of caries.

Conclusions

These findings support the view that most of current national caries data for DMFT levels in 12-year-old children are not comparable across Europe.

Compliance of referral and hospital documentation with National Institute of Health and Care Excellence guidelines for the extraction of third molars: a comparative analysis of two NHS Trusts

To find out whether documentation for the extraction of wisdom teeth complies with National Institute of Health and Care Excellence (NICE) guidelines, we reviewed the referral letters and hospital notes of patients treated at the maxillofacial unit of two NHS Trusts (A: 314 records and B: 280) over 12 months (1 September 2012 to 31 August 2013). Compliance was assessed as unsatisfactory ("indication for extraction not mentioned", "incorrect indication", "indication unclear") or satisfactory ("correct indication implied", "correct indication explicit"). The grade of the clinician who examined the patient was also recorded. A total of 194/314 (62%) referral letters in Trust A and 126/280 (45%) in Trust B were unsatisfactory (p<0.001). Hospital notes were unsatisfactory in 168/323 (52%) and 87/297 (29%) of cases, respectively (p<0.001). In Trust A, middle grades saw 23% (75/323) of the patients, as compared with 53% (157/297) in Trust B. In both, junior staff produced the highest percentage of satisfactory documentation, but in Trust A they were also responsible for most of the unsatisfactory examples. However, senior house officers saw 60% (195/323) of the patients in Trust A, and only 28% (83/297) in Trust B. Consultants were responsible for significantly more unsatisfactory documentation (p<0.001). One referral letter (0.2%) and seven hospital records (1%) explicitly and accurately complied with the guidelines. We conclude that compliance of documentation with the current NICE guidelines is poor and inconsistent.

Pathogenesis of Colitis in Germ-Free Mice Infected With EHEC O157:H7

Enterohemorrhagic Escherichia coli (EHEC) are strains of E. coli that express Shiga toxins (Stx) and cause hemorrhagic colitis. In some cases, disease can progress to hemolytic uremic syndrome, a potentially fatal form of kidney disease. Both enteric and renal disease are associated with the expression of stx genes, which are often carried on lysogenic phage. Toxin is expressed following induction and conversion of the phage to lytic growth. The authors previously used a germ-free mouse model to demonstrate that toxin gene expression is enhanced during growth in vivo and that renal disease is dependent on both prophage induction and expression of Stx2. In the current study, the authors document and quantify necrotizing colitis, examine the progression of enteric and renal disease, and determine the role of Stx2, phage genes, and the type 3 secretion system (T3SS) in bacterial colonization and colitis and systemic disease. By 1 day after inoculation, EHEC-monocolonized mice developed colitis, which decreased in severity thereafter. Systemic disease developed subsequently. Infection with EHEC mutant strains revealed that renal failure and splenic necrosis were absolutely dependent on the expression of Stx2 but that T3SS function and prophage excision were not necessary for systemic disease. In contrast, colitis was only partly dependent on Stx2. This study demonstrates that in germ-free mice, like in human patients, EHEC causes early colitis followed by renal failure and that systemic disease but not colitis is Stx2 dependent.

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

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^flox/flox) 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.

Siderophore vaccine conjugates protect against uropathogenic Escherichia coli urinary tract infection

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.

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

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.

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

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.

Animal Model Reveals Potential Waterborne Transmission of Helicobacter pylori Infection

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.

Humanized microbiota mice as a model of recurrent Clostridium difficile disease

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.

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

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.

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

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.

A pilot project to improve the oral health of orphans and of the elderly in residential care in Constanta, Romania

AIM

A pilot project to improve the oral health of Romanian orphans and elderly people in residential homes.

MATERIAL AND METHODS

The orphanage and old persons' home were in Constanta. After training, 50 fifth-year dental students made 14 weekly residential home visits to improve carers' oral health knowledge and oral hygiene (OH) procedures and to monitor progress in one orphan and one old person. At baseline and after 14 weeks a local dental school staff member examined each orphan and old person's oral health using WHO (1997) criteria and the Simplified Oral Hygiene Index (OHI-S). The carers' knowledge of OH and attitudes to providing and the students' knowledge and attitudes were assessed at baseline and again after 14 weeks with a questionnaire.

RESULTS

All 56 orphans (mean age 9.6 years, mean DMFT 2.39) living in the home participated and their mean OHI-S improved (1.40 to 0.80, p < 0.0001). Fifty old people (mean age 75.9 years) participated, of whom 22 (44%) were edentulous. There was no significant improvement in mean OHI-S (p < 0.10). The carers' oral health knowledge improved (mean scores from 65 to 88, p < 0.001) as did their attitude score (p < 0.013). Students noted changes in their understanding of the needs of the carers, orphans and elderly people. Their perception of their capability to provide OH education or train others to do so, or their inclination to do so remained substantially unchanged.

CONCLUSIONS

This pilot study met its aims suggesting that with suitable management, senior dental students can play a significant role in residential homes for orphans and old people by training carers and improving the residents' oral hygiene. Further similar studies in other settings are indicated.

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

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.

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

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.

Introducing dental hygienists in general practice to research - an in-practice evaluation programme in the United Kingdom

AIM

To introduce dental hygienists (DHs) in the UK to the principles of research through a practice-based product evaluation programme.

METHODS

The programme consisted of an initial training and orientation day with presentations on evidence-based practice, research methods and the structure of research papers. The programme and its aims were explained in detail, and participants were briefed on the methods to be used. Participants then recruited seven to ten patients from their practices (offices), carried out a baseline assessment of: plaque, gingival health, calculus and staining at anterior teeth, and gave the patients a questionnaire asking about their teeth and then provided a 3-month supply of a test toothpaste. About 10 weeks later, a follow-up assessment of the same variables was performed and the questionnaire was repeated. A second training day followed during which the DHs provided feedback of their experiences and received training in literature searching and critical appraisal of literature including interpretation of results.

RESULTS

Sixty-five DHs attended the first training day; 31 were able to recruit sufficient patients and attend the second training day. The DHs recruited 168 patients who received baseline and follow-up assessments. All the variables improved overall. Feedback from the DHs was very positive, and patients expressed delight with the care they had received.

CONCLUSIONS

Qualitative feedback for participating DHs suggests the programme met its aim and could be used in the future as a mechanism for helping DHs who want to increase their understanding of research methodology.

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

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.

How is research publishing going to progress in the next 20 years? Transcription of session for editors, associate editors, publishers and others with an interest in scientific publishing held at IADR meeting in Seattle on Wednesday, 20 March 2013

On March 20th 2013, a one-hour session for Editors, Associate Editors, Publishers and others with an interest in scientific publishing was held at the IADR International Session in Seattle. Organised by Kenneth Eaton and Chris Lynch (Chair and Secretary, respectively, of the British Dental Editors Forum), the meeting sought to bring together leading international experts in dental publishing, as well as authors, reviewers and students engaged in research. The meeting was an overwhelming success, with more than 100 attendees. A panel involving four leading dental editors led a discussion on anticipated developments in publishing dental research with much involvement and contribution from audience members. This was the third such meeting held at the IADR for Editors, Associate Editors, Publishers and others with an interest in scientific publishing. A follow up session will take place in Cape Town on 25 June 2014 as part of the annual IADR meeting. The transcript of the meeting is reproduced in this article. Where possible speakers are identified by name. At the first time of mention their role/ position is also stated, thereafter only their name appears. We are grateful to Stephen Hancocks Ltd for their generous sponsorship of this event. For those who were not able to attend the authors hope this article gives a flavour of the discussions and will encourage colleagues to attend future events. Involvement is open to Editors, Associate Editors, Publishers and others with an interest in scientific publishing. It is a very open group and all those with an interest will be welcome to join in.

Gut microbiota protects against gastrointestinal tumorigenesis caused by epithelial injury

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.

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

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.

Gli1 deletion prevents Helicobacter-induced gastric metaplasia and expansion of myeloid cell subsets

Chronic inflammation in the stomach induces metaplasia, the pre-cancerous lesion that precedes inflammation-driven neoplastic transformation. While Hedgehog signaling contributes to the initiation of some cancers, its role in gastric transformation remains poorly defined. We found that Helicobacter-infected C57BL/6 mice develop extensive mucous cell metaplasia at 6 month but not at 2 months post-infection. Gastric metaplasia coincided with the appearance of CD45⁺MHCII⁺CD11b⁺CD11c⁺ myeloid cells that were normally not present in the chronic gastritis at 2 months. The myeloid regulatory gene Schlafen-4 was identified in a microarray analysis comparing infected WT versus Gli1 null mice and was expressed in the CD11b⁺CD11c⁺ myeloid population. Moreover this same population expressed IL-1β and TNFα pro-inflammatory cytokines. By 6 months, the mucous neck cell metaplasia (SPEM) expressed IL-6, phosphorylated STAT3 and the proliferative marker Ki67. Expression was not observed in Gli1 mutant mice consistent with the requirement of Gli1 to induce this pre-neoplastic phenotype. Ectopic Shh ligand expression alone was not sufficient to induce SPEM, but with Helicobacter infection synergistically increased the histologic severity observed with the inflammation. Therefore Hedgehog signaling is required, but is not sufficient to generate pre-neoplastic changes during chronic gastritis. Gli1-dependent myeloid cell differentiation plays a pivotal role in the appearance of myeloid cell subtypes ostensibly required for SPEM development. Moreover, it suggests that therapies capable of targeting this phenotypic switch might prevent progression to metaplasia, the pre-neoplastic change that develops prior to dysplasia and gastric cancer, which also occurs in other epithelial-derived neoplasias initiated by chronic inflammation.

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

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.

Isolation of gastric lamina propria leukocytes

Immune cells recruited to the infected gastric mucosa can be isolated and used for a variety of purposes. Here we describe methods for the isolation and characterization of gastric lamina propria leukocytes.

Adoptive transfer of splenocytes to immunocompromised mice

Analysis of the immune response of mice to Helicobacter infection has been greatly aided by the use of various deficient mouse strains. Here we present protocols for reconstitution of immune-deficient mice with wild-type immune cells and protocols for analysis of the outcome.

Transgenic expression of interferon-γ in mouse stomach leads to inflammation, metaplasia, and dysplasia

Gastric adenocarcinoma is one of the leading causes of cancer mortality worldwide. It arises through a stepwise process that includes prominent inflammation with expression of interferon-γ (IFN-γ) and multiple other pro-inflammatory cytokines. We engineered mice expressing IFN-γ under the control of the stomach-specific H(+)/K(+) ATPase β promoter to test the potential role of this cytokine in gastric tumorigenesis. Stomachs of H/K-IFN-γ transgenic mice exhibited inflammation, expansion of myofibroblasts, loss of parietal and chief cells, spasmolytic polypeptide expressing metaplasia, and dysplasia. Proliferation was elevated in undifferentiated and metaplastic epithelial cells in H/K-IFN-γ transgenic mice, and there was increased apoptosis. H/K-IFN-γ mice had elevated levels of mRNA for IFN-γ target genes and the pro-inflammatory cytokines IL-6, IL-1β, and tumor necrosis factor-α. Intracellular mediators of IFN-γ and IL-6 signaling, pSTAT1 and pSTAT3, respectively, were detected in multiple cell types within stomach. H/K-IFN-γ mice developed dysplasia as early as 3 months of age, and 4 of 39 mice over 1 year of age developed antral polyps or tumors, including one adenoma and one adenocarcinoma, which expressed high levels of nuclear β-catenin. Our data identified IFN-γ as a pivotal secreted factor that orchestrates complex changes in inflammatory, epithelial, and mesenchymal cell populations to drive pre-neoplastic progression in stomach; however, additional alterations appear to be required for malignant conversion.

IFNγ contributes to the development of gastric epithelial cell metaplasia in Huntingtin interacting protein 1 related (Hip1r)-deficient mice

Huntingtin interacting protein 1 related (Hip1r) is an F-actin- and clathrin-binding protein involved in vesicular trafficking that is crucial for parietal cell function and epithelial cell homeostasis in the stomach. Gastric parietal cells in Hip1r-deficient mice are lost by apoptotic cell death, which leads to a progressive epithelial cell derangement, including glandular hypertrophy, zymogenic cell loss and expansion of a metaplastic mucous cell lineage known as spasmolytic polypeptide-expressing metaplasia (SPEM). The epithelial cell changes are associated with infiltration of inflammatory cells. As inflammatory mediators, such as IFNγ, have been shown to contribute to the development of the gastric epithelial cell metaplasia after Helicobacter infection, we tested whether IFNγ played a role in the spontaneous progressive epithelial metaplasia observed in Hip1r-deficient mice. Hip1r-deficient mice were crossed with IFNγ-deficient mice and single- and double-mutant mice were analyzed at 3 and 12 months of age. Histopathology scoring showed that loss of IFNγ tempered the spontaneous development of metaplastic lesions in Hip1r-deficient mice. Loss of IFNγ was observed to abrogate the glandular hypertrophy evident in Hip1r mutant stomach, although increased epithelial cell proliferation and elevated gastrin levels were not affected by the presence or absence of this pro-inflammatory cytokine. An analysis of cell lineage markers in the double-mutant mice demonstrated that IFNγ specifically affected the development of metaplastic mucous cells in the neck region, whereas the parietal cell, surface mucous cell and zymogenic cell alterations remained similar to the histopathology in the Hip1r mutant. Morphometric analysis showed that IFNγ was required for the mucous cell hypertrophy and hyperplasia observed in Hip1r-deficient mice. Together, these findings demonstrate that IFNγ is critical for the development of the gastric epithelial cell metaplasia that results from parietal cell atrophy in the Hip1r-deficient mice.