The effects of aerobic exercise on the intestinal tumors and flora of the ApcMin/+ mouse.

INTRODUCTION: Intestinal tumor is one of the most common tumors that seriously threaten the health of residents all over the world. Studies suggest that the imbalance of intestinal flora is associated with tumorgenesis; meanwhile, long-term regular aerobic exercise can improve the occurrence and development of tumors. However, moderate aerobic exercise affecting the development of intestinal tumors and their related flora has not been explored. Thus, the purpose of our study is to explore the effects of aerobic exercise on intestinal tumor growth and flora changes in ApcMin/+ mice, and try to answer whether there is a correlation between them after exercise intervention. METHODS: In this study, 18 required ApcMin/+ mice were randomly divided into Model group (n = 6), Exercise group (n = 6), and Aspirin group (positive control, n = 6), while C57BL/6 J wild-type mice were used as the blank control group. Each group is given corresponding intervention. Weight monitoring, tumor counts, hematoxylin-eosin staining, TdT-mediated dUTP nick-end labeling (TUNEL) fluorescence assay, immunohistochemistry (IHC), fecal sampling and grouping, and bacterial 16S rDNA gene analysis were completed after 12 weeks' intervention for each group of mice. RESULTS: As a result, we were able to show significant improvements in mice' body weight changing rates (Exercise group 8.6% higher than Model control group), tumor numbers (Exercise group 4.33 ± 0.94 vs. Model control group 7.33 ± 2.49, Then put the slides into xylenewith tumor inhibition rate 40.93%), tumor pathological staging (Exercise group mainly low-grade tumorous adenomas vs. Model group mainly high-grade adenomas), and TUNEL staining (Exercise group 8.59% higher positive rate of apoptotic cells in tumors than Model group). The 16s rRNA sequencing analysis results showed that aerobic exercise could regulate the abundance of some genus (16/149, P < 0.01), and the number of intestinal tumors correlates with changes in the abundance of some bacteria in the intestinal flora (positive correlation with probiotics abundance and negative correlation with conditioned pathogens). DISCUSSION: Changes in flora abundance may be one of the reasons for aerobic exercise to reduce the number of intestinal tumors, probably mediated by cell apoptosis. Future studies should focus on the potential mechanism of aerobic exercise in preventing intestinal tumorgenesis, especially the molecular mechanism through intestinal flora. CONCLUSION: Aerobic exercise has a preventive effect on intestinal tumors in ApcMin/+ mice, and can regulate the abundance of intestinal flora.

GMrepo v2: a curated human gut microbiome database with special focus on disease markers and cross-dataset comparison.

GMrepo (data repository for Gut Microbiota) is a database of curated and consistently annotated human gut metagenomes. Its main purposes are to increase the reusability and accessibility of human gut metagenomic data, and enable cross-project and phenotype comparisons. To achieve these goals, we performed manual curation on the meta-data and organized the datasets in a phenotype-centric manner. GMrepo v2 contains 353 projects and 71,642 runs/samples, which are significantly increased from the previous version. Among these runs/samples, 45,111 and 26,531 were obtained by 16S rRNA amplicon and whole-genome metagenomics sequencing, respectively. We also increased the number of phenotypes from 92 to 133. In addition, we introduced disease-marker identification and cross-project/phenotype comparison. We first identified disease markers between two phenotypes (e.g. health versus diseases) on a per-project basis for selected projects. We then compared the identified markers for each phenotype pair across datasets to facilitate the identification of consistent microbial markers across datasets. Finally, we provided a marker-centric view to allow users to check if a marker has different trends in different diseases. So far, GMrepo includes 592 marker taxa (350 species and 242 genera) for 47 phenotype pairs, identified from 83 selected projects. GMrepo v2 is freely available at: https://gmrepo.humangut.info.

Analysis of abnormal intestinal flora on risk of intestinal cancer and effect of heparin on formation of bacterial biofilm.

To study the effect of abnormal intestinal flora on the risk of colorectal cancer and the effect of heparin on the formation of bacterial biofilm, 50 patients with colorectal cancer and 50 healthy subjects were selected. The distribution and quantity of bacteria in feces, the levels of D-lactic acid and endotoxin in serum of the two groups were detected. Intestinal flora strains and biofilm growth were also detected in patients with colorectal cancer cultured in different heparin concentrations (0 mg/mL, 5 mg /mL, 10 mg/mL, and 20 mg/mL). The results showed that there was significant difference in the number of major strains of intestinal flora between healthy subjects and colorectal cancer patients before and after operation (P < 0.05). The serum D-lactic acid levels (1.41 ± 0.39, 6.38 ± 1.42 µg/mL) and endotoxin levels (0.62 ± 0.09, 0.80 ± 0.15 EU/mL) in the experimental group were higher than those in the control group (0.91 ± 0.52 µg/mL) (0.05 ± 0.02 EU/mL) before and after operation (P < 0.05). The amount of biofilm formation increased significantly with the increase of heparin concentration (P < 0.05). In summary, there was a close relationship between the occurrence of colorectal cancer and abnormal intestinal flora. Heparin may have a positive effect on regulating intestinal flora in patients with colorectal cancer, which provided certain reference value for the treatment of colorectal cancer.

Molecular profiling and identification of prognostic factors in Chinese patients with small bowel adenocarcinoma.

Small bowel adenocarcinoma (SBA) is a rare malignancy with a poor prognosis and limited treatment options. Despite prior studies, molecular characterization of this disease is not well defined, and little is known regarding Chinese SBA patients. In this study, we conducted multigene next-generation sequencing and 16S ribosomal RNA gene sequencing on samples from 76 Chinese patients with surgically resected primary SBA. Compared with colorectal cancer and Western SBA cohorts, a distinctive genomic profile was revealed in Chinese SBA cohorts. According to the levels of clinical actionability to targetable alterations stratified by OncoKB system, 75% of patients harbored targetable alterations, of which ERBB2, BRCA1/2, and C-KIT mutations were the most common targets of highest-level actionable alterations. In DNA mismatch repair-proficient (pMMR) patients, significant associations between high tumor mutational burden and specific genetic alterations were identified. Moreover, KRAS mutations/TP53 wild-type/nondisruptive mutations (KRASmut /TP53wt/non-dis ) were independently associated with an inferior recurrence-free survival (hazard ratio [HR] = 4.21, 95% confidence interval [CI] = 1.94-9.14, P < .001). The bacterial profile revealed Proteobacteia, Actinobacteria, Firmicutes, Bacteroidetes, Fusobacteria, and Cyanobacteria were the most common phyla in SBA. Furthermore, patients were clustered into three subgroups based on the relative abundance of bacterial phyla, and the distributions of the subgroups were significantly associated with the risk of recurrence stratified by TP53 and KRAS mutations. In conclusion, these findings provided a comprehensive molecular basis for understanding SBA, which will be of great significance in improving the treatment strategies and clinical management of this population.

Functions of Dendritic Cells and Its Association with Intestinal Diseases.

Dendritic cells (DCs), including conventional DCs (cDCs) and plasmacytoid DCs (pDCs), serve as the sentinel cells of the immune system and are responsible for presenting antigen information. Moreover, the role of DCs derived from monocytes (moDCs) in the development of inflammation has been emphasized. Several studies have shown that the function of DCs can be influenced by gut microbes including gut bacteria and viruses. Abnormal changes/reactions in intestinal DCs are potentially associated with diseases such as inflammatory bowel disease (IBD) and intestinal tumors, allowing DCs to be a new target for the treatment of these diseases. In this review, we summarized the physiological functions of DCs in the intestinal micro-environment, their regulatory relationship with intestinal microorganisms and their regulatory mechanism in intestinal diseases.

Helicobacter pylori cagE, cagG, and cagM can be a prognostic marker for intestinal and diffuse gastric cancer.

It is known that Helicobacter pylori is the main cause of peptic ulceration and gastric cancer. However, there is a lack of information on whether H. pylori strains may differ in gastric cancer histological subtypes. This study aimed to investigate different H. pylori strains considering six cag Pathogenicity Island - cagPAI genes (cagA, cagE, cagG, cagM, cagT, and virb11), and vacuolating cytotoxin - vacA alleles, and their relation to gastric cancer histologic subtypes. For this purpose, tumor samples from 285 patients with gastric carcinoma were used. H. pylori infection and genotypes were determined by polymerase chain reaction (PCR). H. pylori was detected in 93.9% of gastric tumors. For comparative analyzes between histopathological subtypes considering H. pylori cagPAI genes the strains were grouped according to the vacA s1/s2 alleles. In the vacAs1 group, the strains cagA(-)cagE(+), cagA(+)cagE(+)cagG(+), cagA(+)cagM(+), or only cagE(+) strains were more frequent in the intestinal subtype (P = .009; P = .024; P = .046, respectively). In contrast, cagM(+)cagG(+)cagA(-) and cagE(-) were associated with diffuse tumors (P = .036), highlighting the presence of cagE in the development of intestinal tumors, and the presence of cagG and absence of cagE in diffuse tumors. Furthermore, WEKA software and Decision Tree (CART) analyses confirmed these findings, in which cagE presence was associated with intestinal tumors, and cagE absence and cagG(+) with diffuse tumors. In conclusion our results showed that vacAs1 (cagG + cagM) strains, mainly cagG positive with cagE absence, were relevant in the studied population for the diffuse outcome, while the presence of cagE was relevant for the intestinal outcome. These findings suggest the relevance of these H. pylori genes as potential markers for gastric cancer histological outcomes.

Endogenous murine microbiota member Faecalibaculum rodentium and its human homologue protect from intestinal tumour growth.

The microbiota has been shown to promote intestinal tumourigenesis, but a possible anti-tumourigenic effect has also been postulated. Here, we demonstrate that changes in the microbiota and mucus composition are concomitant with tumourigenesis. We identified two anti-tumourigenic strains of the microbiota-Faecalibaculum rodentium and its human homologue, Holdemanella biformis-that are strongly under-represented during tumourigenesis. Reconstitution of ApcMin/+ or azoxymethane- and dextran sulfate sodium-treated mice with an isolate of F. rodentium (F. PB1) or its metabolic products reduced tumour growth. Both F. PB1 and H. biformis produced short-chain fatty acids that contributed to control protein acetylation and tumour cell proliferation by inhibiting calcineurin and NFATc3 activation in mouse and human settings. We have thus identified endogenous anti-tumourigenic bacterial strains with strong diagnostic, therapeutic and translational potential.

Clostridium butyricum, a butyrate-producing probiotic, inhibits intestinal tumor development through modulating Wnt signaling and gut microbiota.

Gut microbiota dysbiosis is closely involved in intestinal carcinogenesis. A marked reduction in butyrate-producing bacteria has been observed in patients with colorectal cancer (CRC); nevertheless, the potential benefit of butyrate-producing bacteria against intestinal tumor development has not been fully investigated. We found that Clostridium butyricum (C. butyricum, one of the commonly used butyrate-producing bacteria in clinical settings) significantly inhibited high-fat diet (HFD)-induced intestinal tumor development in Apcmin/+ mice. Moreover, intestinal tumor cells treated with C. butyricum exhibited decreased proliferation and increased apoptosis. Additionally, C. butyricum suppressed the Wnt/ß-catenin signaling pathway and modulated the gut microbiota composition, as demonstrated by decreases in some pathogenic bacteria and bile acid (BA)-biotransforming bacteria and increases in some beneficial bacteria, including short-chain fatty acid (SCFA)-producing bacteria. Accordingly, C. butyricum decreased the fecal secondary BA contents, increased the cecal SCFA quantities, and activated G-protein coupled receptors (GPRs), such as GPR43 and GPR109A. The anti-proliferative effect of C. butyricum was blunted by GPR43 gene silencing using small interfering RNA (siRNA). The analysis of clinical specimens revealed that the expression of GPR43 and GPR109A gradually decreased from human normal colonic tissue to adenoma to carcinoma. Together, our results show that C. butyricum can inhibit intestinal tumor development by modulating Wnt signaling and gut microbiota and thus suggest the potential efficacy of butyrate-producing bacteria against CRC.

Detection of the Bacteroides fragilis toxin gene in sheep with and without small intestinal adenocarcinoma.

Aims: To determine if presence of the Bacteroides fragilis toxin (bft) gene, a molecular marker of colonic carriage of entertoxigenic Bacteroides fragilis (ETBF) in humans, was associated with a finding of small intestinal adenocarcinomas (SIA) in sheep in New Zealand. Methods: Samples of jejunal tissue were collected from the site of tumours and from grossly normal adjacent tissue in 20 sheep, in different consignments, diagnosed with SIA based on gross examination of viscera following slaughter. Two jejunal samples were also collected from a control sheep in the same consignment that had no gross evidence of SIA. A PCR assay was used to detect the presence of the bft gene in the samples. Results: Of the sheep with SIA, the bft gene was amplified from one or both samples from 7/20 (35%) sheep, and in sheep that had no gross evidence of SIA the bft gene was amplified from at least one sample in 11/20 (55%) sheep (RR 0.61; 95% CI = 0.30-1.25; p = 0.34). Of 11 positive samples analysed, ETBF subtype bft-1 was detected in one, bft-2 was detected in 10, and none were bft-3. Conclusions and Clinical Relevance: There was a high prevalence of detection of the bft gene in both SIA-affected and non-affected sheep, but there was no apparent association between carriage of ETBF, evidenced by detection of the bft gene, and the presence of SIA. ETBF are increasingly implicated in the aetiology of human colorectal cancer, raising the possibility that sheep may provide a zoonotic reservoir of this potentially carcinogenic bacterium. Abbreviation: Bft: Bacteroides fragilis toxin; ETBF: Enterotoxigenic Bacteroides fragilis; SIA: Small intestinal adenocarcinoma.

Relationship of the mucosal microbiota to gastrointestinal inflammation and small cell intestinal lymphoma in cats.

BACKGROUND: The gastrointestinal (GI) microbiota in healthy cats is altered in IBD. Little research has been performed to identify whether specific bacterial groups are associated with small cell GI lymphoma (LSA). HYPOTHESIS: Mucosal bacteria, including Enterobacteriaceae and Fusobacterium spp., are abundant in intestinal biopsies of cats with small cell GI LSA compared to cats with IBD. ANIMALS: Fourteen cats with IBD and 14 cats with small cell GI LSA. METHODS: Retrospective case control study. A search of the medical records was performed to identify cats diagnosed with IBD and with GI LSA. Bacterial groups identified by FISH in GI biopsies were compared between cohorts and correlated to CD11b+ and NF-κB expression. RESULTS: Fusobacterium spp. (median; IQR bacteria/region) were higher in cats with small cell GI LSA in ileal (527; 455.5 - 661.5; P = .046) and colonic (404.5; 328.8 - 455.5; P = .016) adherent mucus, and combined colonic compartments (free mucus, adherent mucus, attaching to epithelium) (8; 0 - 336; P = .017) compared to cats with IBD (ileum: 67; 31.5 - 259; colon: 142.5; 82.3 - 434.5; combined: 3; 0 - 34). Bacteroides spp. were higher in ileal adherent mucus (P = .036) and 3 combined ileal compartments (P = .034) of cats with small cell GI LSA. There were significant correlations between Fusobacterium spp. totals and CD11b+ cell (P = .009; rs .476) and NF-κB expression (P = .004; rs .523). CONCLUSIONS: The bacterial alterations appreciated might be influential in development of small cell GI LSA, and should drive further studies to elucidate the effects of microbial-mediated inflammation on GI cancer progression.

Transmission of a common intestinal neoplasm in zebrafish by cohabitation.

Intestinal neoplasms are common in zebrafish (Danio rerio) research facilities. These tumours are most often seen in older fish and are classified as small cell carcinomas or adenocarcinomas. Affected fish populations always contain subpopulations with preneoplastic lesions, characterized by epithelial hyperplasia or inflammation. Previous observations indicated that these tumours are unlikely caused by diet, water quality or genetic background, suggesting an infectious aetiology. We performed five transmission experiments by exposure of naïve fish to affected donor fish by cohabitation or exposure to tank effluent water. Intestinal lesions were observed in recipient fish in all exposure groups, including transmissions from previous recipient fish, and moribund fish exhibited a higher prevalence of neoplasms. We found a single 16S rRNA sequence, most similar to Mycoplasma penetrans, to be highly enriched in the donors and exposed recipients compared to unexposed control fish. We further tracked the presence of the Mycoplasma sp. using a targeted PCR test on individual dissected intestines or faeces or tank faeces. Original donor and exposed fish populations were positive for Mycoplasma, while corresponding unexposed control fish were negative. This study indicates an infectious aetiology for these transmissible tumours of zebrafish and suggests a possible candidate agent of a Mycoplasma species.

Fecal microbiome in dogs with inflammatory bowel disease and intestinal lymphoma.

Although alteration of commensal microbiota is associated with chronic gastrointestinal (GI) diseases such as inflammatory bowel disease (IBD) in dogs, the microbiota composition in intestinal lymphoma, an important differential diagnosis of canine IBD, has not been investigated. The objective of this study was to compare the fecal microbiota in dogs with IBD, dogs with intestinal lymphoma, and healthy dogs. Eight dogs with IBD, eight dogs with intestinal lymphoma, and fifteen healthy dogs were included in the study. Fecal samples were analyzed by 16S rRNA gene next-generation sequencing. Rarefaction analysis failed to reveal any difference in bacterial diversity among healthy dogs and diseased dogs. Based on PCoA plots of unweighted UniFrac distances, the bacterial composition in dogs with intestinal lymphoma was different from those observed in dogs with IBD and healthy dogs. When compared with healthy dogs, intestinal lymphoma subjects showed significant increases in organisms belonging to the Eubacteriaceae family. The proportion of the family Paraprevotellaceae and the genus Porphyromonas was significantly higher in dogs with IBD compared to healthy dogs. These observations suggest that dysbiosis is associated with intestinal lymphoma as well as IBD in dogs.

Helicobacter pylori genotypes determine risk of non-cardia gastric cancer and intestinal- or diffuse-type GC in Ardabil: A very high-risk area in Northwestern Iran.

Frequency of the Helicobacter pylori vacA gene polymorphism and its association with gastric cancer (GC) was assessed in Ardabil, a very high-risk area in Northwestern Iran. We determined the presence of the H. pylori 16S rDNA gene and the vacA s-, m-, i-, and d-region genotypes in DNA from fresh gastric biopsies. Patients with GC were classified based on both the anatomic site and the histopathologic type of tumor Of 135 patients, including 57 with non-atrophic gastritis (NAG) and 78 with GC, 103 were infected by H. pylori. The vacA i1 and d1 genotypes were significantly linked to an increased risk of GC, where both cardia (CGC) and non-cardia GC (NCGC) patients were entered into the analysis. The adjusted OR was 9.59 for i1 and 4.39 for d1. Furthermore, i1 was significantly linked to an increased risk of the intestinal-type adenocarcinoma (OR = 14.04) and d1 to the risk of the diffuse-type adenocarcinoma (OR = 7.71). The presence of the m1-type of vacA in combination with i1 or d1 further increased the risk of GC. When the analysis was restricted to NCGC, the adjusted OR for i1 and d1, was 37.52 and 7.17, respectively. No significant association was found between genotypes and the risk of GC in the cardia site of the stomach. It is proposed that the new types of H. pylori vacA, i1 and d1, might be important determinants of NCGC risk in Ardabil. The m1, not independently, but in combination might further define the risk of GC. i1and d1 might also predict the risk of the intestinal- and diffuse-type adenocarcinomas, respectively.

Risk factors for intestinal metaplasia in a southeastern Chinese population: an analysis of 28,745 cases.

PURPOSE: To identify risk factors for intestinal metaplasia in a southeastern Chinese population. METHODS: Subjects who underwent upper GI endoscopy and endoscopic biopsy in the First Affiliated Hospital of Nanjing Medical University from 2008 to 2013 were included into this study. Various demographic, geographic, clinical and pathological data were analyzed separately to identify risk factors for intestinal metaplasia. RESULTS: The incidence of intestinal metaplasia differed significantly in 17 municipal areas ranging from 16.79 to 38.56% and was positively correlated with the age range of 40-70 years, male gender, gastric ulcer, bile reflux, Helicobacter pylori infection, atrophic gastritis, dysplasia, gastric cancer, degree of chronic and acute inflammation, and gross domestic product per capita (P < 0.01). Multivariate linear regression analysis indicated that only gross domestic product per capita revealed a significant difference in the incidence of intestinal metaplasia among all factors mentioned. CONCLUSION: This study confirms age, male gender, gastric ulcer, bile reflux, H. pylori infection, severe degree of chronic and acute inflammation to be the risk factors for intestinal metaplasia. We speculate that the gross domestic product per capita of different areas may be a potential independent risk factor impacting the incidence of intestinal metaplasia.

Intestinal Organoids: New Frontiers in the Study of Intestinal Disease and Physiology.

The development of sustainable intestinal organoid cell culture has emerged as a new modality for the study of intestinal function and cellular processes. Organoid culture is providing a new testbed for therapeutic research and development. Intestinal organoids, self-renewing 3-dimensional structures comprised intestinal stem cells and their differentiated epithelial progeny allow for more facile and robust exploration of cellular activity, cell organization and structure, genetic manipulation, and vastly more physiologic modeling of intestinal response to stimuli as compared to traditional 2-dimensional cell line cultures. Intestinal organoids are affecting a wide variety of research into gastrointestinal pathology. The purpose of this review is to discuss the current state-of-the-art and future effect of research using enteroids and colonoids (organoids grown from the small and large intestines, respectively).

Identification of Mucosa-Invading and Intravascular Bacteria in Feline Small Intestinal Lymphoma.

Persistent bacterial infections of the gastrointestinal mucosa are causally linked to gastric carcinoma and mucosa-associated lymphoid tissue (MALT) lymphoma in people and laboratory animals. We examined the relationship of mucosa-associated bacteria to alimentary lymphoma in cats. Intestinal biopsies from 50 cats with alimentary lymphoma (small cell, n = 33; large cell, n = 17) and 38 controls without lymphoma (normal to minimal change on histopathology, n = 18; lymphocytic-plasmacytic enteritis, n = 20) were evaluated. The number and spatial distribution of bacteria (ie, in luminal cellular debris, villus-associated mucus, adherent to epithelium, mucosal invasion, intravascular, or serosal) were determined by fluorescence in situ hybridization with the eubacterial probe EUB-338. Mucosa-invasive bacteria were more frequently observed in cats with large cell lymphoma (82%, P ≤ .001) than in cats with small cell lymphoma (18%), normal to minimal change on histopathology, and lymphocytic-plasmacytic enteritis (3%). Intravascular bacteria were observed solely in large cell lymphoma (29%), and serosal colonization was more common in cats with large cell lymphoma (57%) than with small cell lymphoma (11%, P ≤ .01), normal to minimal change (8%, P ≤ .01), and lymphocytic-plasmacytic enteritis (6%, P ≤ .001). The high frequency of invasive bacteria within blood vessels and serosa of cats with large cell lymphoma may account for the sepsis-related complications associated with large cell lymphoma and inform clinical management. Further studies are required to determine the role of intramucosal bacteria in the etiopathogenesis of feline alimentary lymphoma.

Changes in intestinal immunity, gut microbiota, and expression of energy metabolism-related genes explain adenoma growth in bilberry and cloudberry-fed ApcMin mice.

We showed previously that ellagitannin-rich cloudberries and anthocyanin-rich bilberries reduce the number of intestinal adenomas in multiple intestinal neoplasia/+ (ApcMin) mice. We also found that cloudberries decreased the size of adenomas, whereas bilberries increased it. Here we hypothesized that the difference in adenoma growth could be explained by dissimilar effects of the berries on intestinal immune responses and gut microbiota, potentially driven by the distinct polyphenol compositions of the 2 berries. Our objectives were to investigate lymphocyte subtypes and the predominant cecal bacterial diversity in mice fed with bilberries and cloudberries, and to analyze global gene expression profiles in the intestinal mucosa. Immunostainings of CD3+ T lymphocytes, FoxP3+ regulatory T lymphocytes, and CD45R+ B lymphocytes revealed a smaller ratio of intraepithelial to all mucosal CD3+ T lymphocytes in the cloudberry-fed mice compared with controls, suggesting an attenuation of inflammation. Bilberry feeding induced no changes in the density of any of the lymphocyte subtypes. The predominant bacterial diversity in cecal contents, analyzed using polymerase chain reaction-denaturating gradient gel electrophoresis, was higher in the bilberry group than in the control or cloudberry groups. The microbial profiles of cloudberry-fed mice clustered together and were associated with small adenoma size. Pathway analyses of gene expression data showed that cloudberry down-regulated and bilberry up-regulated the expression of energy metabolism-related genes in the intestinal mucosa. In conclusion, attenuation of intestinal inflammation, changes in microbial profiles, and down-regulation of mucosal energy metabolism may account for the smaller adenoma size in cloudberry-fed mice in comparison to bilberry-fed mice.

Interactions between the colonic transcriptome, metabolome, and microbiome in mouse models of obesity-induced intestinal cancer.

Obesity is a significant risk factor for colorectal cancer (CRC); however, the relative contribution of high-fat (HF) consumption and excess adiposity remains unclear. It is becoming apparent that obesity perturbs both the intestinal microbiome and metabolome, and each has the potential to induce protumorigenic changes in the epithelial transcriptome. The physiological consequences and the degree to which these different biologic systems interact remain poorly defined. To understand the mechanisms by which obesity drives colonic tumorigenesis, we profiled the colonic epithelial transcriptome of HF-fed and genetically obese (DbDb) mice with a genetic predisposition to intestinal tumorigenesis (Apc(1638N)); 266 and 584 genes were differentially expressed in the colonic mucosa of HF and DbDb mice, respectively. These genes mapped to pathways involved in immune function, and cellular proliferation and cancer. Furthermore, Akt was central within the networks of interacting genes identified in both gene sets. Regression analyses of coexpressed genes with the abundance of bacterial taxa identified three taxa, previously correlated with tumor burden, to be significantly correlated with a gene module enriched for Akt-related genes. Similarly, regression of coexpressed genes with metabolites found that adenosine, which was negatively associated with inflammatory markers and tumor burden, was also correlated with a gene module enriched with Akt regulators. Our findings provide evidence that HF consumption and excess adiposity result in changes in the colonic transcriptome that, although distinct, both appear to converge on Akt signaling. Such changes could be mediated by alterations in the colonic microbiome and metabolome.

Epithelial calcineurin controls microbiota-dependent intestinal tumor development.

Inflammation-associated pathways are active in intestinal epithelial cells (IECs) and contribute to the pathogenesis of colorectal cancer (CRC). Calcineurin, a phosphatase required for the activation of the nuclear factor of activated T cells (NFAT) family of transcription factors, shows increased expression in CRC. We therefore investigated the role of calcineurin in intestinal tumor development. We demonstrate that calcineurin and NFAT factors are constitutively expressed by primary IECs and selectively activated in intestinal tumors as a result of impaired stratification of the tumor-associated microbiota and toll-like receptor signaling. Epithelial calcineurin supports the survival and proliferation of cancer stem cells in an NFAT-dependent manner and promotes the development of intestinal tumors in mice. Moreover, somatic mutations that have been identified in human CRC are associated with constitutive activation of calcineurin, whereas nuclear translocation of NFAT is associated with increased death from CRC. These findings highlight an epithelial cell-intrinsic pathway that integrates signals derived from the commensal microbiota to promote intestinal tumor development.

Lipocalin 2 Protects from Inflammation and Tumorigenesis Associated with Gut Microbiota Alterations.

High mucosal and fecal concentrations of the antimicrobial siderophore-binding peptide Lipocalin-2 (Lcn2) are observed in inflammatory bowel disease. However, Lcn2 function in chronic intestinal inflammation remains unclear. Here, we demonstrate that Lcn2 protects from early-onset colitis and spontaneous emergence of right-sided colonic tumors resulting from IL-10 deficiency. Exacerbated inflammation in Lcn2(-/-)/Il10(-/-) mice is driven by IL-6, which also controls tumorigenesis. Lcn2(-/-)/Il10(-/-) mice exhibit profound alterations in gut microbial composition, which contributes to inflammation and tumorigenesis, as demonstrated by the transmissibility of the phenotype and protection conferred by antibiotics. Specifically, facultative pathogenic Alistipes spp. utilize enterobactin as iron source, bloom in Lcn2(-/-)/Il10(-/-) mice, and are sufficient to induce colitis and right-sided tumors when transferred into Il10(-/-) mice. Our results demonstrate that Lcn2 protects against intestinal inflammation and tumorigenesis associated with alterations in the microbiota.