The alarming prevalence of inflammatory bowel disease (IBD) in early childhood is associated with imbalances in the microbiome, the immune response, and environmental factors. Some pathogenic Escherichia coli (E. coli) strains have been found in IBD patients, where they may influence disease progression. Therefore, the discovery of new harmful bacterial strains that have the potential to drive the inflammatory response is of great importance. In this study, we compared the immunomodulatory properties of two E. coli strains of serotype O6: the probiotic E. coli Nissle 1917 and the uropathogenic E. coli O6:K13:H1. Using the epithelial Caco-2 cell line, we investigated the different abilities of the strains to adhere to and invade epithelial cells. We confirmed the potential of E. coli Nissle 1917 to modulate the Th1 immune response in a specific manner in an in vitro setting by stimulating mouse bone marrow-derived dendritic cells (BM-DCs). In gnotobiotic in vivo experiments, we demonstrated that neonatal colonization with E. coli Nissle 1917 achieves a stable high concentration in the intestine and protects mice from the progressive effect of E. coli O6:K13:H1 in developing ulcerative colitis in an experimental model. In contrast, a single-dose treatment with E. coli Nissle 1917 is ineffective in achieving such high concentrations and does not protect against DSS-induced ulcerative colitis in mice neonatally colonized with pathobiont E. coli O6:K13:H1. Despite the stable coexistence of both E. coli strains in the intestinal environment of the mice, we demonstrated a beneficial competitive interaction between the early colonizing E. coli Nissle 1917 and the late-arriving strain O6:K13:H1, suggesting its anti-inflammatory potential for the host. This study highlights the importance of the sequence of bacterial colonization, which influences the development of the immune response in the host gut and potentially impacts future quality of life.

• Keywords
• DSS-experimental colitis, Escherichia coli, immune modulation, mouse model, priority effect,
• Publication type
• Journal Article MeSH

Butyrate, a metabolite produced by gut bacteria, has demonstrated beneficial effects in the colon and has been used to treat inflammatory bowel diseases. However, the mechanism by which butyrate operates remains incompletely understood. Given that oral butyrate can exert either a direct impact on the gut mucosa or an indirect influence through its interaction with the gut microbiome, this study aimed to investigate three key aspects: (1) whether oral intake of butyrate modulates the expression of genes encoding short-chain fatty acid (SCFA) transporters (Slc16a1, Slc16a3, Slc16a4, Slc5a8, Abcg2) and receptors (Hcar2, Ffar2, Ffar3, Olfr78, Olfr558) in the colon, (2) the potential involvement of gut microbiota in this modulation, and (3) the impact of oral butyrate on the expression of colonic SCFA transporters and receptors during colonic inflammation. Specific pathogen-free (SPF) and germ-free (GF) mice with or without DSS-induced inflammation were provided with either water or a 0.5% sodium butyrate solution. The findings revealed that butyrate decreased the expression of Slc16a1, Slc5a8, and Hcar2 in SPF but not in GF mice, while it increased the expression of Slc16a3 in GF and the efflux pump Abcg2 in both GF and SPF animals. Moreover, the presence of microbiota was associated with the upregulation of Hcar2, Ffar2, and Ffar3 expression and the downregulation of Slc16a3. Interestingly, the challenge with DSS did not alter the expression of SCFA transporters, regardless of the presence or absence of microbiota, and the effect of butyrate on the transporter expression in SPF mice remained unaffected by DSS. The expression of SCFA receptors was only partially affected by DSS. Our results indicate that (1) consuming a relatively low concentration of butyrate can influence the expression of colonic SCFA transporters and receptors, with their expression being modulated by the gut microbiota, (2) the effect of butyrate does not appear to result from direct substrate-induced regulation but rather reflects an indirect effect associated with the gut microbiome, and (3) acute colon inflammation does not lead to significant changes in the transcriptional regulation of most SCFA transporters and receptors, with the effect of butyrate in the inflamed colon remaining intact.

• Keywords
• butyrate, butyrate receptors, butyrate transporters, colitis, dextran sulfate, germ-free (GF), microbiota, short chain fatty acid (SCFA),
• Publication type
• Journal Article MeSH

Several studies have indicated the beneficial anti-inflammatory effect of butyrate in inflammatory bowel disease (IBD) therapy implying attempts to increase butyrate production in the gut through orally administered dietary supplementation. Through the gut-liver axis, however, butyrate may reach directly the liver and influence the drug-metabolizing ability of hepatic enzymes, and, indirectly, also the outcome of applied pharmacotherapy. The focus of our study was on the liver microsomal cytochrome P450 (CYP) 2A5, which is a mouse orthologue of human CYP2A6 responsible for metabolism of metronidazole, an antibiotic used to treat IBD. Our findings revealed that specific pathogen-free (SPF) and germ-free (GF) mice with dextran sulfate sodium (DSS)-induced colitis varied markedly in enzyme activity of CYP2A and responded differently to butyrate pre-treatment. A significant decrease (to 50%) of the CYP2A activity was observed in SPF mice with colitis; however, an administration of butyrate prior to DSS reversed this inhibition effect. This phenomenon was not observed in GF mice. The results highlight an important role of gut microbiota in the regulation of CYP2A under inflammatory conditions. Due to the role of CYP2A in metronidazole metabolism, this phenomenon may have an impact on the IBD therapy. Butyrate administration, hence, brings promising therapeutic potential for improving symptoms of gut inflammation; however, possible interactions with drug metabolism need to be further studied.

• Keywords
• butyrate, cytochromes P450, germ-free mice, gut inflammation, gut–liver axis, hepatic drug metabolism, microbiome,
• MeSH
• Anti-Bacterial Agents adverse effects   pharmacology   therapeutic use   MeSH
• Anti-Inflammatory Agents pharmacology   MeSH
• Butyrates * pharmacology   MeSH
• Metronidazole pharmacology   MeSH
• Disease Models, Animal MeSH
• Mice, Inbred C57BL MeSH
• Mice MeSH
• Dextran Sulfate adverse effects   MeSH
• Gastrointestinal Microbiome * MeSH
• Cytochrome P-450 Enzyme System metabolism   MeSH
• Colitis, Ulcerative * chemically induced   drug therapy   MeSH
• Animals MeSH
• Check Tag
• Mice MeSH
• Animals MeSH
• Publication type
• Journal Article MeSH
• Names of Substances
• Anti-Bacterial Agents MeSH
• Anti-Inflammatory Agents MeSH
• Butyrates * MeSH
• Metronidazole MeSH
• Dextran Sulfate MeSH
• Cytochrome P-450 Enzyme System MeSH

The development of inflammatory bowel disease (IBD) is associated with alterations in the gut microbiota. There is currently no universal treatment for this disease, thus emphasizing the importance of developing innovative therapeutic approaches. Gut microbiome-derived metabolite butyrate with its well-known anti-inflammatory effect in the gut is a promising candidate. Due to increased intestinal permeability during IBD, butyrate may also reach the liver and influence liver physiology, including hepatic drug metabolism. To get an insight into this reason, the aim of this study was set to clarify not only the protective effects of the sodium butyrate (SB) administration on colonic inflammation but also the effects of SB on hepatic drug metabolism in experimental colitis induced by dextran sodium sulfate (DSS) in mice. It has been shown here that the butyrate pre-treatment can alleviate gut inflammation and reduce the leakiness of colonic epithelium by restoration of the assembly of tight-junction protein Zonula occludens-1 (ZO-1) in mice with DSS-induced colitis. In this article, butyrate along with inflammation has also been shown to affect the expression and enzyme activity of selected cytochromes P450 (CYPs) in the liver of mice. In this respect, CYP3A enzymes may be very sensitive to gut microbiome-targeted interventions, as significant changes in CYP3A expression and activity in response to DSS-induced colitis and/or butyrate treatment have also been observed. With regard to medications used in IBD and microbiota-targeted therapeutic approaches, it is important to deepen our knowledge of the effect of gut inflammation, and therapeutic interventions were followed concerning the ability of the organism to metabolize drugs. This gut-liver axis, mediated through inflammation as well as microbiome-derived metabolites, may affect the response to IBD therapy.

• Keywords
• butyrate, cytochromes P450, drug metabolism, gut inflammation, gut–liver axis,
• Publication type
• Journal Article MeSH

Cancer, bacteria, and immunity relationships are much-debated topics in the last decade. Microbiome's importance for metabolic and immunologic modulation of the organism adaptation and responses has become progressively evident, and models to study these relationships, especially about carcinogenesis, have acquired primary importance. The availability of germ-free (GF) animals, i.e., animals born and maintained under completely sterile conditions avoiding the microbiome development offers a unique tool to investigate the role that bacteria can have in carcinogenesis and tumor development. The comparison between GF animals with the conventional (CV) counterpart with microbiome can help to evidence conditions and mechanisms directly involving bacterial activities in the modulation of carcinogenesis processes. Here, we review the literature about spontaneous cancer and cancer modeling in GF animals since the early studies, trying to offer a practical overview on the argument.

• Keywords
• colorectal cancer, germ-free animals, induced tumors, microbiome, spontaneous tumors,
• MeSH
• Bacteria MeSH
• Germ-Free Life * MeSH
• Carcinogenesis MeSH
• Microbiota * MeSH
• Animals MeSH
• Check Tag
• Animals MeSH
• Publication type
• Journal Article MeSH
• Review MeSH

The aim of this study was to investigate the use of a standardized animal model subjected to antibiotic treatment, and the effects of this treatment on the course of dextran sodium sulphate (DSS)-induced colitis in mice. By decontamination with selective antibiotics and observation of pathogenesis of ulcerative colitis (UC) induced chemically by exposure of mice to various concentrations of DSS, we obtained an optimum animal PGF model of acute UC manifested by mucin depletion, epithelial degeneration and necrosis, leading to the disappearance of epithelial cells, infiltration of lamina propria and submucosa with neutrophils, cryptitis, and accompanied by decreased viability of intestinal microbiota, loss of body weight, dehydration, moderate rectal bleeding, and a decrease in the selected markers of cellular proliferation and apoptosis. The obtained PGF model did not exhibit changes that could contribute to inflammation by means of alteration of the metabolic status and the induced dysbiosis did not serve as a bearer of pathogenic microorganisms participating in development of ulcerative colitis. The inflammatory process was induced particularly by exposure to DSS and its toxic action on compactness and integrity of mucosal barrier in the large intestine. This offers new possibilities of the use of this animal model in studies with or without participation of pathogenic microbiota in IBD pathogenesis.

• Keywords
• DSS-induced colitis, antibiotics, gut microbiota, histopathology, pseudo germ-free model,
• MeSH
• Anti-Bacterial Agents pharmacology   MeSH
• Apoptosis physiology   MeSH
• Epithelial Cells pathology   MeSH
• Disease Models, Animal MeSH
• Mice, Inbred BALB C MeSH
• Mice MeSH
• Cell Proliferation physiology   MeSH
• Dextran Sulfate pharmacology   MeSH
• Gastrointestinal Microbiome drug effects   physiology   MeSH
• Intestinal Mucosa microbiology   pathology   MeSH
• Colitis, Ulcerative chemically induced   drug therapy   pathology   MeSH
• Inflammation drug therapy   pathology   MeSH
• Animals MeSH
• Check Tag
• Mice MeSH
• Female MeSH
• Animals MeSH
• Publication type
• Journal Article MeSH
• Research Support, Non-U.S. Gov't MeSH
• Names of Substances
• Anti-Bacterial Agents MeSH
• Dextran Sulfate MeSH

Diet is a major factor determining gut microbiota composition and perturbances in this complex ecosystem are associated with the inflammatory bowel disease (IBD). Here, we used gnotobiotic approach to analyze, how interaction between diet rich in proteins and gut microbiota influences the sensitivity to intestinal inflammation in murine model of ulcerative colitis. We found that diet rich in animal protein (aHPD) exacerbates acute dextran sulfate sodium (DSS)-induced colitis while diet rich in plant protein (pHPD) does not. The deleterious effect of aHPD was also apparent in chronic DSS colitis and was associated with distinct changes in gut bacteria and fungi. Therefore, we induced acute DSS-colitis in germ-free mice and transferred gut microbiota from aCD or aHPD fed mice to find that this effect requires presence of microbes and aHPD at the same time. The aHPD did not change the number of regulatory T cells or Th17 cells and still worsened the colitis in immuno-deficient RAG2 knock-out mice suggesting that this effect was not dependent on adaptive immunity. The pro-inflammatory effect of aHPD was, however, abrogated when splenic macrophages were depleted with clodronate liposomes. This treatment prevented aHPD induced increase in colonic Ly-6Chigh pro-inflammatory monocytes, but the ratio of resident Ly-6C-/low macrophages was not changed. These data show that the interactions between dietary protein of animal origin and gut microbiota increase sensitivity to intestinal inflammation by promoting pro-inflammatory response of monocytes.

• Keywords
• colitis, dietary protein, germ-free, macrophage, microbiota,
• MeSH
• Adaptive Immunity immunology   MeSH
• Th17 Cells immunology   metabolism   MeSH
• Diet adverse effects   MeSH
• Dietary Proteins administration & dosage   adverse effects   MeSH
• DNA-Binding Proteins metabolism   MeSH
• Colitis immunology   metabolism   pathology   MeSH
• Colon immunology   metabolism   pathology   MeSH
• Macrophages immunology   metabolism   pathology   MeSH
• Disease Models, Animal MeSH
• Monocytes immunology   metabolism   pathology   MeSH
• Mice, Inbred BALB C MeSH
• Mice, Knockout MeSH
• Mice MeSH
• T-Lymphocytes, Regulatory immunology   metabolism   MeSH
• Intestines immunology   pathology   MeSH
• Gastrointestinal Microbiome immunology   physiology   MeSH
• Inflammation immunology   metabolism   pathology   MeSH
• Animals MeSH
• Check Tag
• Mice MeSH
• Female MeSH
• Animals MeSH
• Publication type
• Journal Article MeSH
• Research Support, Non-U.S. Gov't MeSH
• Names of Substances
• Dietary Proteins MeSH
• DNA-Binding Proteins MeSH

The microbiota is a crucial modulator of the immune system. Here, we evaluated how its absence or reduction modifies the inflammatory response in the murine model of experimental autoimmune uveoretinitis (EAU). We induced EAU in germ-free (GF) or conventionally housed (CV) mice and in CV mice treated with a combination of broad-spectrum antibiotics either from the day of EAU induction or from one week prior to induction of disease. The severity of the inflammation was assessed by fundus biomicroscopy or by histology, including immunohistology. The immunophenotyping of T cells in local and distant lymph nodes was performed by flow cytometry. We found that GF mice and mice where the microbiota was reduced one week before EAU induction were protected from severe autoimmune inflammation. GF mice had lower numbers of infiltrating macrophages and significantly less T cell infiltration in the retina than CV mice with EAU. GF mice also had reduced numbers of IFN-γ and IL-17-producing T cells and increased numbers of regulatory T cells in the eye-draining lymph nodes. These data suggest that the presence of microbiota during autoantigen recognition regulates the inflammatory response by influencing the adaptive immune response.

• MeSH
• Adaptive Immunity MeSH
• Lymphocyte Activation MeSH
• Anti-Bacterial Agents pharmacology   MeSH
• Autoantigens immunology   MeSH
• Autoimmune Diseases chemically induced   immunology   microbiology   MeSH
• Bacterial Load drug effects   MeSH
• Germ-Free Life MeSH
• Interferon-gamma biosynthesis   MeSH
• Interleukin-17 biosynthesis   MeSH
• Macrophages immunology   MeSH
• Microbiota * immunology   MeSH
• Disease Models, Animal MeSH
• Mice, Inbred C57BL MeSH
• Mice MeSH
• Eye immunology   pathology   MeSH
• Eye Proteins immunology   MeSH
• Retinol-Binding Proteins immunology   MeSH
• Flow Cytometry MeSH
• T-Lymphocytes, Regulatory immunology   MeSH
• Retina immunology   MeSH
• Retinitis chemically induced   etiology   immunology   microbiology   MeSH
• Uveitis chemically induced   immunology   microbiology   MeSH
• Animals MeSH
• Check Tag
• Male MeSH
• Mice MeSH
• Female MeSH
• Animals MeSH
• Publication type
• Journal Article MeSH
• Evaluation Study MeSH
• Names of Substances
• Anti-Bacterial Agents MeSH
• Autoantigens MeSH
• Interferon-gamma MeSH
• Interleukin-17 MeSH
• interstitial retinol-binding protein MeSH Browser
• Eye Proteins MeSH
• Retinol-Binding Proteins MeSH

BACKGROUND: Disturbances in the intestinal microbial community (i.e. dysbiosis) or presence of the microbes with deleterious effects on colonic mucosa has been linked to the pathogenesis of inflammatory bowel diseases. However the role of microbiota in induction and progression of ulcerative colitis (UC) has not yet been fully elucidated. METHODS: Three lines of human microbiota-associated (HMA) mice were established by gavage of colon biopsy from three patients with active UC. The shift in microbial community during its transferring from humans to mice was analyzed by next-generation sequencing using Illumina MiSeq sequencer. Spontaneous or dextran sulfate sodium (DSS)-induced colitis and microbiota composition profiling in germ-free mice and HMA mice over 3-4 generations were assessed to decipher the features of the distinctive and crucial events occurring during microbial colonization and animal reproduction. RESULTS: None of the HMA mice developed colitis spontaneously. When treated with DSS, mice in F4 generation of one line of colonized mice (aHMA) developed colitis. Compared to the DSS-resistant earlier generations of aHMA mice, the F4 generation have increased abundance of Clostridium difficile and decrease abundance of C. symbiosum in their cecum contents measured by denaturing gradient gel electrophoresis and DNA sequencing. CONCLUSION: In our study, mucosa-associated microbes of UC patients were not able to induce spontaneous colitis in gnotobiotic BALB/c mice but they were able to increase the susceptibility to DSS-induced colitis, once the potentially deleterious microbes found a suitable niche.

• Keywords
• Dysbiosis, Germ-free mice, Microbiota, Ulcerative colitis,
• Publication type
• Journal Article MeSH

BACKGROUND: Reduced microbial diversity has been associated with inflammatory bowel disease (IBD) and probiotic bacteria have been proposed for its prevention and/or treatment. Nevertheless, comparative studies of strains of the same subspecies for specific health benefits are scarce. Here we compared two Bifidobacterium longum ssp. longum strains for their capacity to prevent experimental colitis. METHODS: Immunomodulatory properties of nine probiotic bifidobacteria were assessed by stimulation of murine splenocytes. The immune responses to B. longum ssp. longum CCM 7952 (Bl 7952) and CCDM 372 (Bl 372) were further characterized by stimulation of bone marrow-derived dendritic cell, HEK293/TLR2 or HEK293/NOD2 cells. A mouse model of dextran sulphate sodium (DSS)-induced colitis was used to compare their beneficial effects in vivo. RESULTS: The nine bifidobacteria exhibited strain-specific abilities to induce cytokine production. Bl 372 induced higher levels of both pro- and anti-inflammatory cytokines in spleen and dendritic cell cultures compared to Bl 7952. Both strains engaged TLR2 and contain ligands for NOD2. In a mouse model of DSS-induced colitis, Bl 7952, but not Bl 372, reduced clinical symptoms and preserved expression of tight junction proteins. Importantly, Bl 7952 improved intestinal barrier function as demonstrated by reduced FITC-dextran levels in serum. CONCLUSIONS: We have shown that Bl 7952, but not Bl 372, protected mice from the development of experimental colitis. Our data suggest that although some immunomodulatory properties might be widespread among the genus Bifidobacterium, others may be rare and characteristic only for a specific strain. Therefore, careful selection might be crucial in providing beneficial outcome in clinical trials with probiotics in IBD.

• MeSH
• Bifidobacterium classification   physiology   MeSH
• Dendritic Cells microbiology   pathology   MeSH
• HEK293 Cells MeSH
• Immunoenzyme Techniques MeSH
• Colitis chemically induced   prevention & control   MeSH
• Humans MeSH
• Disease Models, Animal * MeSH
• Mice, Inbred BALB C MeSH
• Mice MeSH
• Probiotics pharmacology   MeSH
• Nod2 Signaling Adaptor Protein genetics   metabolism   MeSH
• Dextran Sulfate toxicity   MeSH
• Intestines microbiology   physiopathology   MeSH
• Toll-Like Receptor 2 genetics   metabolism   MeSH
• Animals MeSH
• Check Tag
• Humans MeSH
• Mice MeSH
• Female MeSH
• Animals MeSH
• Publication type
• Journal Article MeSH
• Research Support, Non-U.S. Gov't MeSH
• Names of Substances
• Nod2 Signaling Adaptor Protein MeSH
• Dextran Sulfate MeSH
• Tlr2 protein, mouse MeSH Browser
• Toll-Like Receptor 2 MeSH