Differences Between the Intestinal Lumen Microbiota of Aberrant Crypt Foci (ACF)-Bearing and Non-bearing Rats

Background

Multiple factors including host–microbiota interaction could contribute to the conversion of healthy mucosa to sporadic precancerous lesions. An imbalance of the gut microbiota may be a cause or consequence of this process.

Aim

The goal was to investigate and analyze the composition of gut microbiota during the genesis of precancerous lesions of colorectal cancer.

Methods

To analyze the composition of gut microbiota in the genesis of precancerous lesions, a rat model of 1, 2-dimethylhydrazine (DMH)-induced aberrant crypt foci (ACF) was established. The feces of these rats and healthy rats were collected for 16S rRNA sequencing.

Results

The diversity and density of the rat intestinal microbiota were significantly different between ACF-bearing and non-bearing group. ACF were induced in rats treated with DMH and showed increased expression of the inflammatory cytokines IL-6, IL-8, and TNF-α. Firmicutes was the most predominant phylum in both ACF-bearing and non-bearing group, followed by Bacteroidetes. Interestingly, although the density of Bacteroidetes decreased from the fifth week to the 17th week in both groups, it was significantly reduced in ACF-bearing group at the 13th week (P?<?0.01). At the genus level, no significant difference was observed in the most predominant genus, Lactobacillus. Instead, Bacteroides and Prevotella were significantly less abundant (P?<?0.01), while Akkermansia was significantly more abundant (P?<?0.05) in ACF-bearing group at the 13th week.

Conclusion

Imbalance of the intestinal microbiota existed between ACF-bearing and non-bearing rats, which could be used as biomarker to predict the genesis of precancerous lesions in the gut.

     

Altered Gut Microbiota Composition and Immune Response in Experimental Steatohepatitis Mouse Models

Background

Although several types of diet have been used in experimental steatohepatitis models, comparison of gut microbiota and immunological alterations in the gut among diets has not yet been performed.

Aim

We attempted to clarify the difference in the gut environment between mice administrated several experimental diets.

Methods

Male wild-type mice were fed a high-fat (HF) diet, a choline-deficient amino acid-defined (CDAA) diet, and a methionine-choline-deficient (MCD) diet for 8 weeks. We compared the severity of steatohepatitis, the composition of gut microbiota, and the intestinal expression of interleukin (IL)-17, an immune modulator.

Results

Steatohepatitis was most severe in the mice fed the CDAA diet, followed by the MCD diet, and the HF diet. Analysis of gut microbiota showed that the composition of the Firmicutes phylum differed markedly at order level between the mice fed the CDAA and HF diet. The CDAA diet increased the abundance of Clostridiales, while the HF diet increased that of lactate-producing bacteria. In addition, the CDAA diet decreased the abundance of lactate-producing bacteria and antiinflammatory bacterium Parabacteroides goldsteinii in the phylum Bacteroidetes. In CDAA-fed mice, IL-17 levels were increased in ileum as well as portal vein. In addition, the CDAA diet also elevated hepatic expression of chemokines, downstream targets of IL-17.

Conclusions

The composition of gut microbiota and IL-17 expression varied considerably between mice administrated different experimental diets to induce steatohepatitis.

     

Oncogenic miR-23a in Pancreatic Ductal Adenocarcinogenesis Via Inhibiting <Emphasis Type="Italic">APAF1</Emphasis>

Background

miR-23a, which participates in invasion of pancreatic ductal adenocarcinoma cells into the mesothelial barrier, is a critical regulator in many cancers. It, however, is still unknown whether miR-23a regulates pancreatic cell proliferation and apoptosis or not.

Aims

We sought to investigate the role of miR-23a in regulation of pancreatic cell proliferation and apoptosis.

Methods

miRNA, mRNA, and protein expressions were determined by qRT-PCR and Western blot, respectively. Dual-luciferase reporter assay was used in detection for binding ability of miR-23a to APAF1. Ectopic miR-23a and APAF 1 were introduced to pancreatic cells, and their roles in proliferation and apoptosis were detected by MTT, colony formation, and apoptosis assays, respectively.

Results

Up-regulation of miR-23a and down-regulation of APAF 1 were found in pancreatic ductal cancer, respectively. miR-23a significantly inhibited the luciferase activity by targeting APAF 1 3′UTR. Ectopic miR-23a significantly suppressed the APAF 1 gene expression in pancreatic cancer cells. Similar to siAPAF1, miR-23a significantly promoted pancreatic cancer cell proliferation and repressed apoptosis. Furthermore, miR-23a inhibitor and exogenous APAF 1 could recover the effects.

Conclusions

It is suggested that miR-23a, acting as an oncogenic regulator by directly targeting APAF 1 in pancreatic cancer, is a useful potential biomarker in diagnosis and treatment of pancreatic cancer.

     

The DPP-4 inhibitor vildagliptin impacts the gut microbiota and prevents disruption of intestinal homeostasis induced by a Western diet in mice

Aims/hypothesis

Dipeptidyl peptidase 4 (DPP-4) inhibitors are agents designed to increase the half-life of incretins. Although they are administered orally, little is known about their effects on the gut microbiota and functions, despite the fact that some bacteria present in the gut microbiota exhibit DPP-4-like activity. Our objective was to study the impact of the DPP-4 inhibitor vildagliptin on gut functions and the intestinal ecosystem in a murine model of obesity induced by a Western diet (WD).

Methods

Twenty seven male C57BL/6J mice were randomised to receive a control diet, a WD (45% kJ from fat and 17% kJ from sucrose) or a WD + vildagliptin (0.6 mg/ml in drinking water) for 8 weeks.

Results

Vildagliptin significantly reduced DPP-4 activity in the caecal content and faeces. Vildagliptin impacted on the composition of the gut microbiota and its metabolic activity. It mainly decreased Oscillibacter spp. (a direct effect independent of DPP-4 activity was shown on cultured O. valericigenes), increased Lactobacillus spp. and propionate, and reduced the ligands of Toll-like receptors 2 and 4. Vildagliptin protected against the reductions in crypt depth and ileal expression of antimicrobial peptides induced by the WD. In the liver, the expression of immune cell populations (Cd3g and Cd11c [also known as Itgax]) and cytokines was decreased in the WD + vildagliptin-fed mice compared with the WD-fed group. Ex vivo exposure of precision-cut liver slices to vildagliptin showed that this response was not related to a direct effect of the drug on the liver tissue.

Conclusions/interpretation

Our study is the first to consider the DPP-4-like activity of the gut microbiota as a target of DPP-4 inhibition. We propose that vildagliptin exerts beneficial effects at the intestinal level in association with modulation of gut microbiota, with consequences for hepatic immunity. If relevant in humans, this could open new therapeutic uses of DPP-4 inhibition to tackle gut dysfunctions in different pathophysiological contexts.

Data availability

The sequences used for analysis can be found in the MG-RAST database under the project name MYNEWGUT3.

     

Stool Microbiota Composition Differs in Patients with Stomach,Colon, and Rectal Neoplasms

Background

Microbial ecosystems that inhabit the human gut form central component of our physiology and metabolism, regulating and modulating both health and disease. Changes or disturbances in the composition and activity of this gut microbiota can result in altered immunity, inflammation, and even cancer.

Aim

To compare the composition and diversity of gut microbiota in stool samples from patient groups based on the site of neoplasm in the gastrointestinal tract (GIT) and to assess the possible contribution of the bacterial composition to tumorigenesis.

Methods

We studied gut microbiota by16S RNA gene sequencing from stool DNA of 83 patients, who were diagnosed with different GIT neoplasms, and 13 healthy individuals.

Results

As compared to healthy individuals, stools of patients with stomach neoplasms had elevated levels of Enterobacteriaceae, and those with rectal neoplasms had lower levels of Bifidobacteriaceae. Lower abundance of Lactobacillaceae was seen in patients with colon neoplasms. Abundance of Lactobacillaceae was higher in stools of GIT patients sampled after cancer treatment compared to samples collected before start of any treatment. In addition to site-specific differences, higher abundances of Ruminococcus, Subdoligranulum and lower abundances of Lachnoclostridium and Oscillibacter were observed in overall GIT neoplasms as compared to healthy controls

Conclusion

Our study demonstrates that the alterations in gut microbiota vary according to the site of GIT neoplasm. The observed lower abundance of two common families, Lactobacillaceae and Bifidobacteriaceae, and the increased abundance of Enterobacteriaceae could provide indicators of compromised gut health and potentially facilitate GIT disease monitoring.

     

A human stool-derived <Emphasis Type="Italic">Bilophila wadsworthia</Emphasis> strain caused systemic inflammation in specific-pathogen-free mice

Background

Bilophila wadsworthia is a major member of sulfidogenic bacteria in human gut, it was originally recovered from different clinical specimens of intra-abdominal infections and recently was reported potentially linked to different chronic metabolic disorders. However, there is still insufficient understanding on its detailed function and mechanism to date.

Methods

A B. wadsworthia strain was isolated from fresh feces of a latent autoimmune diabetes in adults patient and we investigated its pathogenicity by oral administration to specific-pathogen-free mice. Tissue samples and serum were collected after sacrifice. Stool samples were collected at different time points to profile the gut microbiota.

Results

Bilophila wadsworthia infection resulted in the reduction of body weight and fat mass, apparent hepatosplenomegaly and elevated serum inflammatory factors, including serum amyloid A and interleukin-6, while without significant change of the overall gut microbiota structure.

Conclusions

These results demonstrated that higher amount of B. wadsworthia caused systemic inflammatory response in SPF mice, which adds new evidence to the pathogenicity of this bacterium and implied its potential role to the chronic inflammation related metabolic diseases like diabetes.

     

Gut Microbiota Composition Before and After Use of Proton Pump Inhibitors

Background

Recently, problems associated with proton pump inhibitor (PPI) use have begun to surface. PPIs influence the gut microbiota; therefore, PPI use may increase the risk of enteric infections and cause bacterial translocation. In this study, we investigated fecal microbiota composition, fecal organic acid concentrations and pH, and gut bacteria in the blood of the same patients before and after PPI use.

Methods

Twenty patients with reflux esophagitis based on endoscopic examination received 8 weeks of treatment with PPIs. To analyze fecal microbiota composition and gut bacteria in blood and organic acid concentrations, 16S and 23S rRNA-targeted quantitative RT-PCR and high-performance liquid chromatography were conducted.

Results

Lactobacillus species were significantly increased at both 4 and 8 weeks after PPI treatment compared with bacterial counts before treatment (P?=?0.011 and P?=?0.002, respectively). Among Lactobacillus spp., counts of the L. gasseri subgroup, L. fermentum, the L. reuteri subgroup, and the L. ruminis subgroup were significantly increased at 4 and 8 weeks after treatment compared with counts before treatment. Streptococcus species were also significantly increased at 4 and 8 weeks after PPI treatment compared with counts before treatment (P?<?0.01 and P?<?0.001, respectively). There was no significant difference in the total organic acid concentrations before and after PPI treatment. Detection rates of bacteria in blood before and after PPI treatment were 22 and 28%, respectively, with no significant differences.

Conclusions

Our quantitative RT-PCR results showed that gut dysbiosis was caused by PPI use, corroborating previous results obtained by metagenomic analysis.

     

Sphenoid sinus microbiota in pituitary apoplexy: a preliminary study

Purpose

There is a high incidence of abnormal sphenoid sinus changes in patients with pituitary apoplexy (PA). Their pathophysiology is currently unexplored and may reflect an inflammatory or infective process. In this preliminary study, we characterised the microbiota of sphenoid sinus mucosa in patients with PA and compared findings to a control group of surgically treated non-functioning pituitary adenomas (NFPAs).

Methods

In this prospective observational study of patients undergoing trans-sphenoidal surgery for PA or NFPA, sphenoid sinus mucosal specimens were microbiologically profiled through PCR-cloning of the 16S rRNA gene.

Results

Ten patients (five with PA and five with NFPAs) with a mean age of 51 years (range 23–71) were included. Differences in the sphenoid sinus microbiota of the PA and NFPA groups were observed. Four PA patients harboured Enterobacteriaceae (Enterobacter spp., N = 3; Escherichia coli, N = 1). In contrast, patients with NFPAs had a sinus microbiota more representative of health, including Staphylococcus epidermidis (N = 2) or Corynebacterium spp. (N = 2).

Conclusions

PA may be associated with an abnormal sphenoid sinus microbiota that is similar to that seen in patients with sphenoid sinusitis.

     

A decrease in anaerobic bacteria promotes <Emphasis Type="Italic">Candida glabrata</Emphasis> overgrowth while β-glucan treatment restores the gut microbiota and attenuates colitis

Background

The intestinal microbiota plays a crucial role in the maintenance of gut homeostasis. Changes in crosstalk between the intestinal epithelial cells, immune cells and the microbiota are critically involved in the development of inflammatory bowel disease. In the experimental mouse model, the development of colitis induced by dextran sulfate sodium (DSS) promotes overgrowth of the opportunistic yeast pathogen Candida glabrata. Conversely, fungal colonization aggravates inflammatory parameters. In the present study, we explored the effect of C. glabrata colonization on the diversity of the gut microbiota in a DSS-induced colitis model, and determined the impact of soluble β-glucans on C. glabrata-host interactions.

Results

Mice were administered a single inoculum of C. glabrata and were exposed to DSS treatment for 2 weeks in order to induce acute colitis. For β-glucan treatment, mice were administered with soluble β-glucans purified from C. glabrata (3?mg per mouse), orally and daily, for 5 days, starting on day 1. The number of C. glabrata colonies and changes in microbiota diversity were assessed in freshly collected stool samples from each tagged mouse, using traditional culture methods based on agar plates. An increase in Escherichia coli and Enterococcus faecalis populations and a reduction in Lactobacillus johnsonii and Bacteroides thetaiotaomicron were observed during colitis development. This decrease in L. johnsonii was significantly accentuated by C. glabrata overgrowth. Oral administration of β-glucans to mice decreased the overgrowth of aerobic bacteria and IL-1β expression while L. johnsonii and B. thetaiotaomicron populations increased significantly. β-glucan treatment increased IL-10 production via PPARγ sensing, promoting the attenuation of colitis and C. glabrata elimination.

Conclusions

This study shows that the colonic inflammation alters the microbial balance, while β-glucan treatment increases the anaerobic bacteria and promotes colitis attenuation and C. glabrata elimination.

     

Update on the Gastrointestinal Microbiome in Systemic Sclerosis

Purpose of Review

Accumulating evidence suggests that gut microbiota affect the development and function of the immune system and may play a role in the pathogenesis of autoimmune diseases. The purpose of this review is to summarize recent studies reporting gastrointestinal microbiota aberrations associated with the systemic sclerosis disease state.

Recent Findings

The studies described herein have identified common changes in gut microbial composition. Specifically, patients with SSc have decreased abundance of beneficial commensal genera (e.g., Faecalibacterium, Clostridium, and Bacteroides) and increased abundance of pathobiont genera (e.g., Fusobacterium, Prevotella, Erwinia). In addition, some studies have linked specific genera with the severity of gastrointestinal symptoms in systemic sclerosis.

Summary

More research is needed to further characterize the gastrointestinal microbiota in systemic sclerosis and understand how microbiota perturbations can affect inflammation, fibrosis, and clinical outcomes. Interventional studies aimed at addressing/correcting these perturbations, either through dietary modification, pro/pre-biotic supplementation, or fecal transplantation, may lead to improved outcomes for patients with systemic sclerosis.

     

Effects of hepatic glycogen on food intake and glucose homeostasis are mediated by the vagus nerve in mice

Aims/hypothesis

Liver glycogen plays a key role in regulating food intake and blood glucose. Mice that accumulate large amounts of this polysaccharide in the liver are protected from high-fat diet (HFD)-induced obesity by reduced food intake. Furthermore, these animals show reversal of the glucose intolerance and hyperinsulinaemia caused by the HFD. The aim of this study was to examine the involvement of the hepatic branch of the vagus nerve in regulating food intake and glucose homeostasis in this model.

Methods

We performed hepatic branch vagotomy (HBV) or a sham operation on mice overexpressing protein targeting to glycogen (Ptg ^OE). Starting 1 week after surgery, mice were fed an HFD for 10 weeks.

Results

HBV did not alter liver glycogen or ATP levels, thereby indicating that this procedure does not interfere with hepatic energy balance. However, HBV reversed the effect of glycogen accumulation on food intake. In wild-type mice, HBV led to a significant reduction in body weight without a change in food intake. Consistent with their body weight reduction, these animals had decreased fat deposition, adipocyte size, and insulin and leptin levels, together with increased energy expenditure. Ptg ^OE mice showed an increase in energy expenditure and glucose oxidation, and these differences were abolished by HBV. Moreover, Ptg ^OE mice showed an improvement in HFD-induced glucose intolerance, which was suppressed by HBV.

Conclusions/interpretation

Our results demonstrate that the regulation of food intake and glucose homeostasis by liver glycogen is dependent on the hepatic branch of the vagus nerve.

     

Differences in the gut microbiota of dogs (<Emphasis Type="Italic">Canis lupus familiaris</Emphasis>) fed a natural diet or a commercial feed revealed by the Illumina MiSeq platform

Background

Recent advances in next-generation sequencing technologies have enabled comprehensive analysis of the gut microbiota, which is closely linked to the health of the host. Consequently, several studies have explored the factors affecting gut microbiota composition. In recent years, increasing number of dog owners are feeding their pets a natural diet i.e., one consisting of bones, raw meat (such as chicken and beef), and vegetables, instead of commercial feed. However, the effect of these diets on the microbiota of dogs (Canis lupus familiaris) is unclear.

Methods and results

Six dogs fed a natural diet and five dogs fed a commercial feed were selected; dog fecal metagenomic DNA samples were analyzed using the Illumina MiSeq platform. Pronounced differences in alpha and beta diversities, and taxonomic composition of the core gut microbiota were observed between the two groups. According to alpha diversity, the number of operational taxonomic units, the richness estimates, and diversity indices of microbiota were significantly higher (p < 0.05) in the natural diet group than in the commercial feed group. Based on beta diversity, most samples clustered together according to the diet type (p = 0.004). Additionally, the core microbiota between the two groups was different at the phylum, family, and species levels. Marked differences in the taxonomic composition of the core microbiota of the two groups were observed at the species level; Clostridium perfringens (p = 0.017) and Fusobacterium varium (p = 0.030) were more abundant in the natural diet group.

Conclusions

The gut microbiota of dogs is significantly influenced by diet type (i.e., natural diet and commercial feed). Specifically, dogs fed a natural diet have more diverse and abundant microbial composition in the gut microbiota than dogs fed a commercial feed. In addition, this study suggests that in dogs fed a natural diet, the potential risk of opportunistic infection could be higher, than in dogs fed a commercial feed. The type of diet might therefore play a key role in animal health by affecting the gut microbiota. This study could be the basis for future gut microbiota research in dogs.

     

Exposure to environmental microbiota explains persistent abdominal pain and irritable bowel syndrome after a major flood

Background

After an environmental disaster, the affected community is at increased risk for persistent abdominal pain but mechanisms are unclear. Therefore, our study aimed to determine association between abdominal pain and poor water, sanitation and hygiene (WaSH) practices, and if small intestinal bacterial overgrowth (SIBO) and/or gut dysbiosis explain IBS, impaired quality of life (QOL), anxiety and/or depression after a major flood.

Results

New onset abdominal pain, IBS based on the Rome III criteria, WaSH practices, QOL, anxiety and/or depression, SIBO (hydrogen breath testing) and stools for metagenomic sequencing were assessed in flood victims. Of 211 participants, 37.9% (n = 80) had abdominal pain and 17% (n = 36) with IBS subtyped diarrhea and/or mixed type (n = 27 or 12.8%) being the most common. Poor WaSH practices and impaired quality of life during flood were significantly associated with IBS. Using linear discriminant analysis effect size method, gut dysbiosis was observed in those with anxiety (Bacteroidetes and Proteobacteria, effect size 4.8), abdominal pain (Fusobacteria, Staphylococcus, Megamonas and Plesiomonas, effect size 4.0) and IBS (Plesiomonas and Trabulsiella, effect size 3.0).

Conclusion

Disturbed gut microbiota because of environmentally-derived organisms may explain persistent abdominal pain and IBS after a major environmental disaster in the presence of poor WaSH practices.

     

AICAR ameliorates high-fat diet-associated pathophysiology in mouse and ex vivo models,independent of adiponectin

Aims/hypothesis

In this study, we aimed to evaluate the therapeutic potential of 5-aminoimidazole-4-carboxamide ribonucleotide (AICAR), an activator of AMP-activated protein kinase, for ameliorating high-fat diet (HFD)-induced pathophysiology in mice. We also aimed to determine whether the beneficial effects of AICAR were dependent on adiponectin. Furthermore, human adipose tissue was used to examine the effect of AICAR ex vivo.

Methods

Six-week-old male C57BL/6J wild-type and Adipoq ^?/? mice were fed a standard-fat diet (10% fat) or an HFD (60% fat) for 12 weeks and given vehicle or AICAR (500 μg/g) three times/week from weeks 4–12. Diet-induced pathophysiology was examined in mice after 11 weeks by IPGTT and after 12 weeks by flow cytometry and western blotting. Human adipose tissue biopsies from obese (BMI 35–50 kg/m²) individuals were incubated with vehicle or AICAR (1 mmol/l) for 6 h at 37°C, after which inflammation was characterised by ELISA (TNF-α) and flow cytometry.

Results

AICAR attenuated adipose inflammation in mice fed an HFD, promoting an M1-to-M2 macrophage phenotype switch, while reducing infiltration of CD8⁺ T cells. AICAR treatment of mice fed an HFD partially restored glucose tolerance and attenuated hepatic steatosis and kidney disease, as evidenced by reduced albuminuria (p?<?0.05), urinary H₂O₂ (p?<?0.05) and renal superoxide levels (p?<?0.01) in both wild-type and Adipoq ^?/? mice. AICAR-mediated protection occurred independently of adiponectin, as similar protection was observed in wild-type and Adipoq ^?/? mice. In addition, AICAR promoted an M1-to-M2 macrophage phenotype switch and reduced TNF-α production in tissue explants from obese human patients.

Conclusions/interpretation

AICAR may promote metabolic health and protect against obesity-induced systemic diseases in an adiponectin-independent manner. Furthermore, AICAR reduced inflammation in human adipose tissue explants, suggesting by proof-of-principle that the drug may reduce obesity-induced complications in humans.

Trial registration:

ClinicalTrials.gov NCT02322073

     

Cecal microbiome profile altered by <Emphasis Type="Italic">Salmonella enterica</Emphasis>, serovar Enteritidis inoculation in chicken

Background

Salmonella enterica, serovar Enteritidis (S. Enteritidis), an important zoonotic foodborne pathogen, can affect the microbiota of the chicken intestine and cause many enteric diseases, such as acute gastroenteritis. The gut microbiota contributes to the development and function of the host immune system and competes with pathogenic microbes. The interaction between S. Enteritidis and the host cecal microbiota is still not fully understood. We investigated the microbiome composition in both treated and control groups through 16S ribosomal RNA (rRNA) gene sequencing at 1, 3, 7, 14, 21, 28, and 35 days post-S. Enteritidis inoculation (dpi) in the current study.

Results

Chao1 richness and Shannon diversity significantly increased with chicken development in both the treated and control groups (P?<?0.05). The Chao1 index was significantly lower in the treated group than that in the control group at 14 dpi (P?<?0.05). Phyla Proteobacteria and Firmicutes were most dominant at 1 and 3 dpi. S. Enteritidis inoculation influenced cecal microbiota mainly at 7 and 14 dpi. S. Enteritidis inoculation significantly altered the relative abundance of 18 genera at different time points (P?<?0.05) with relative abundance significantly changed after 14 dpi. The abundance of those genera changed dramatically between 28 and 35 dpi in the treated group compared to control group. Positive correlations existed between Bacillus and Blautia and between Coprococcus and Flavonifractor following S. Enteritidis inoculation.

Conclusions

Our results indicated that both development and S. Enteritidis have effect on chicken cecal microbiota profiles. S. Enteritidis inoculation in young chicks influences the cecal microbiota mainly at 7 and 14 dpi. The cecal microbiota exhibited immunity to S. Enteritidis inoculation at 28 dpi. These findings will provide basic knowledge of the role that chicken cecal microbiota play in response to S. Enteritidis inoculation.

     

Aberrant intestinal microbiota in individuals with prediabetes

Aims/hypothesis

Individuals with type 2 diabetes have aberrant intestinal microbiota. However, recent studies suggest that metformin alters the composition and functional potential of gut microbiota, thereby interfering with the diabetes-related microbial signatures. We tested whether specific gut microbiota profiles are associated with prediabetes (defined as fasting plasma glucose of 6.1–7.0 mmol/l or HbA_1c of 42–48 mmol/mol [6.0–6.5%]) and a range of clinical biomarkers of poor metabolic health.

Methods

In the present case–control study, we analysed the gut microbiota of 134 Danish adults with prediabetes, overweight, insulin resistance, dyslipidaemia and low-grade inflammation and 134 age- and sex-matched individuals with normal glucose regulation.

Results

We found that five bacterial genera and 36 operational taxonomic units (OTUs) were differentially abundant between individuals with prediabetes and those with normal glucose regulation. At the genus level, the abundance of Clostridium was decreased (mean log₂ fold change ?0.64 (SEM 0.23), p _adj ?=?0.0497), whereas the abundances of Dorea, [Ruminococcus], Sutterella and Streptococcus were increased (mean log₂ fold change 0.51 (SEM 0.12), p _adj ?=?5?×?10^?4; 0.51 (SEM 0.11), p _adj ?=?1?×?10^?4; 0.60 (SEM 0.21), p _adj ?=?0.0497; and 0.92 (SEM 0.21), p _adj ?=?4?×?10^?4, respectively). The two OTUs that differed the most were a member of the order Clostridiales (OTU 146564) and Akkermansia muciniphila, which both displayed lower abundance among individuals with prediabetes (mean log₂ fold change ?1.74 (SEM 0.41), p _adj ?=?2?×?10^?3 and ?1.65 (SEM 0.34), p _adj ?=?4?×?10^?4, respectively). Faecal transfer from donors with prediabetes or screen-detected, drug-naive type 2 diabetes to germfree Swiss Webster or conventional C57BL/6 J mice did not induce impaired glucose regulation in recipient mice.

Conclusions/interpretation

Collectively, our data show that individuals with prediabetes have aberrant intestinal microbiota characterised by a decreased abundance of the genus Clostridium and the mucin-degrading bacterium A. muciniphila. Our findings are comparable to observations in overt chronic diseases characterised by low-grade inflammation.

     

Gastrointestinal Tract Pathology in a BALB/c Niemann–Pick Disease Type C1 Null Mouse Model

Background

Niemann–Pick disease, type C (NPC) is a rare lysosomal storage disorder characterized by progressive neurodegeneration, splenomegaly, hepatomegaly, and early death. NPC is caused by mutations in either the NPC1 or NPC2 gene. Impaired NPC function leads to defective intracellular transport of unesterified cholesterol and its accumulation in late endosomes and lysosomes. A high frequency of Crohn disease has been reported in NPC1 patients, suggesting that gastrointestinal tract pathology may become a more prominent clinical issue if effective therapies are developed to slow the neurodegeneration. The Npc1 ^nih mouse model on a BALB/c background replicates the hepatic and neurological disease observed in NPC1 patients. Thus, we sought to characterize the gastrointestinal tract pathology in this model to determine whether it can serve as a model of Crohn disease in NPC1.

Methods

We analyzed the gastrointestinal tract and isolated macrophages of BALB/cJ cNctr-Npc1m1N/J (Npc1^?/?) mouse model to determine whether there was any Crohn-like pathology or inflammatory cell activation. We also evaluated temporal changes in the microbiota by 16S rRNA sequencing of fecal samples to determine whether there were changes consistent with Crohn disease.

Results

Relative to controls, Npc1 mutant mice demonstrate increased inflammation and crypt abscesses in the gastrointestinal tract; however, the observed pathological changes are significantly less than those observed in other Crohn disease mouse models. Analysis of Npc1 mutant macrophages demonstrated an increased response to lipopolysaccharides and delayed bactericidal activity; both of which are pathological features of Crohn disease. Analysis of the bacterial microbiota does not mimic what is reported in Crohn disease in either human or mouse models. We did observe significant increases in cyanobacteria and epsilon-proteobacteria. The increase in epsilon-proteobacteria may be related to altered cholesterol homeostasis since cholesterol is known to promote growth of this bacterial subgroup.

Conclusions

Macrophage dysfunction in the BALB/c Npc1^?/? mouse is similar to that observed in other Crohn disease models. However, neither the degree of pathology nor the microbiota changes are typical of Crohn disease. Thus, this mouse model is not a good model system for Crohn disease pathology reported in NPC1 patients.

     

Wireless Capsule Motility: Comparison of the SmartPill<Superscript>?</Superscript> GI Monitoring System with Scintigraphy for Measuring Whole Gut Transit

Introduction

Assessment of whole gut transit, by radio-opaque markers or scintigraphy, is used to evaluate patients with constipation for slow gastrointestinal transit. Wireless capsule motility, using the SmartPill^® GI monitoring system, samples and transmits intraluminal pH, pressure, and temperature data from a capsule at regular intervals as it traverses through the gastrointestinal tract; from these, gastric emptying and whole gastrointestinal tract transit can be assessed. The objective of this study was to compare the SmartPill^® with whole gut transit scintigraphy to determine whether the SmartPill system could serve as a test for measurement of whole gut motility and transit.

Methods

Ten healthy, asymptomatic subjects underwent simultaneous whole gut scintigraphy and SmartPill^® assessment of whole gut transit.

Results

All subjects completed the study per protocol and experienced natural passage of the pill. Capsule residence time in the stomach correlated very strongly with percent gastric retention of the Tc-99 radiolabel at 120 min (r = 0.95) and at 240 min (r = 0.73). Small bowel contraction-min^?1 measured by the SmartPill correlated with small bowel transit % (r = 0.69; P = 0.05) and with isotopic colonic geometric center at 24 h after ingestion (r = 0.70, P = 0.024). Capsule transit time correlated with scintigraphic assessment of whole gut transit.

Conclusions

SmartPill^® capsule assessment of gastric emptying and whole gut transit compares favorably with that of scintigraphy. Wireless capsule motility shows promise as a useful diagnostic test to evaluate patients for GI transit disorders and to study the effect of prokinetic agents on GI transit.