Dextran sulfate sodium (DSS)-induced colitis is one of the most frequently used rodent models for... more Dextran sulfate sodium (DSS)-induced colitis is one of the most frequently used rodent models for inflammatory bowel disease (IBD). The aim of this study was to validate the murine DSS-induced colitis model using four therapeutic agents for IBD. C57BL/6 mice were exposed to 3% DSS for 5days followed by 7-9 days of water (acute inflammation) or 20-31 days of water (chronic phase). Clinical symptoms, plasma and colonic inflammatory markers and histology were assessed for the efficacy of cyclosporine A (CsA), methotrexate or anti-IL-12p40 in acute colitis and of anti-IL-12p40 or an agonistic anti-CD3 antibody in chronic colitis. Cyclosporine A and anti-IL-12p40 (in the acute phase) and anti-CD3 (in the chronic phase) treatment attenuated local cytokine levels, improved clinical symptoms (CsA and anti-IL-12p40) and histology (CsA and anti-CD3). Further, anti-IL-12p40 treatment was partly efficacious in the chronic phase, whereas methotrexate showed no efficacy in the acute colitis. Thus, three of the current tested agents showed efficacy in the disease model, arguing that DSS-induced colitis can be used as a relevant model for the translation of mice data to human disease.
roton pump inhibitors (PPIs) are the first line Ptreatment for many gastrointestinal conditions a... more roton pump inhibitors (PPIs) are the first line Ptreatment for many gastrointestinal conditions and, since their introduction in the 1980s, PPIs have become the third most prescribed medication in United States. Moreover, PPIs, including omeprazole, are available over the counter in many countries; yet only few realize the increased risk of side effects including developing osteoporosis, electrolyte disorders and the increased risk of Clostridium difficile infection (CDI) via alterations in gut microbiota composition. In the current issue of Gastroenterology, a small open-label intervention trial performed by Freedberg et al aimed to study the effect of relative high dose of PPI (omeprazole) on the colonic microbiota and CDIassociated species in 12 otherwise healthy subjects. Fecal samples were collected twice at baseline (with 4 weeks in between to exclude interindividual differences). Subjects were then randomized to receive either 4 or 8 weeks of PPI followed by fecal sample collection. No effect upon PPI treatment was seen on intestinal microbial diversity; however, Enterococcae and streptococcal strains were significantly increased, whereas Clostridiales species were decreased. With PPI use, fecal bacterial DNA was enriched in genes associated with epithelial bacterial invasion. This study differs from other studies in that it did not find intestinal bacterial overgrowth with PPI use; others have found contradictory results with regard to bacterial overgrowth. Although there are some methodologic shortcomings of the current trial that might have severely impacted results (eg, no dietary intake monitoring, use of relatively high daily PPI doses), the fact that even in healthy subjects the intestinal microbiota are affected by PPI underscores the drastic effects of daily acid suppression on our intestinal bacteria. Moreover, these data provide evidence that regular usage of orally administered drugs (eg, PPI and statins) might affect gut microbiota composition, thus rendering our intestine more vulnerable for pathogen colonization including C difficile. Indeed, altered gut microbiota composition is causally related to CDI overgrowth, because introducing donor feces can eradicate CDI. What are the mechanisms regulated by PPIs on the microbiota that can lead a predisposition for CDI? It has been suggested that primary bile acids can act as germinants for C difficile spores, transforming them into growing bacteria. Certain colonic bacteria can indeed convert primary bile acids to secondary bile acids, and
Annual review of food science and technology, Mar 25, 2022
Diet exerts a major influence upon host immune function and the gastrointestinal microbiota. Alth... more Diet exerts a major influence upon host immune function and the gastrointestinal microbiota. Although components of the human diet (including carbohydrates, fats, and proteins) are essential sources of nutrition for the host, they also influence immune function directly through interaction with innate and cell-mediated immune regulatory mechanisms. Regulation of the microbiota community structure also provides a mechanism by which food components influence host immune regulatory processes. Here, we consider the complex interplay between components of the modern (Western) diet, the microbiota, and host immunity in the context of obesity and metabolic disease, inflammatory bowel disease, and infection.
ABSTRACTConflicting evidence exists on the association between consumption of non-steroidal anti-... more ABSTRACTConflicting evidence exists on the association between consumption of non-steroidal anti-inflammatory drugs (NSAIDs) and symptomatic worsening of inflammatory bowel disease (IBD). We hypothesise that the heterogeneous prevalence of pathobionts [e.g., adherent-invasiveEscherichiacoli (AIEC)], might explain this inconsistent NSAIDs/IBD correlation. UsingIL10-/-mice, we show aggravation of colitis in AIEC-colonised animals fed NSAID. This is accompanied by activation of the NLRP3 inflammasome, Caspase-8, apoptosis and pyroptosis; features not seen in mice exposed to AIEC or NSAID alone, revealing an AIEC/NSAID synergistic effect. Inhibition of NLRP3 or Caspase-8 activity ameliorated colitis, with reduction in NLRP3 inflammasome activation, cell death markers and activated T-cells and macrophages, improved histology and increased abundance ofClostridiumcluster XIVa species. Our findings provide mechanistic insights into how NSAID and an opportunistic gut-pathobiont can synergise to worsen IBD symptoms. Thus, targeting the NLRP3 inflammasome and Caspase-8 could be a potential therapeutic strategy in patients with NSAID-worsened inflammation.
Increased levels of chemokines and prostaglandins have been reported in patients with inflammator... more Increased levels of chemokines and prostaglandins have been reported in patients with inflammatory bowel disease, although their changes during disease development are less understood. The aim of this study was to investigate the local production of nine selected chemokines and prostaglandin E(2) (PGE(2)) to elucidate their role in colitis progression in BALB/c and C57BL/6 mice exposed to dextran sulphate sodium. The acute inflammation in both strains was accompanied by a significant up-regulation of CXCL1, CXCL2/3, CXCL10, CCL2, CCL4 and CCL22 and a downregulation of PGE(2). In the recovery phase in BALB/c, one-week post-DSS, PGE(2) levels were significantly increased with a concomitant downregulation of CXCL1, CXCL2/3, CXCL10, CCL2, and CCL4. In contrast, in C57BL/6 mice CXCL1, CXCL2/3, CXCL10, CCL2, CCL3 and CCL4 production remained high during the chronic phase, without any up-regulation of PGE(2). In addition, CCL5 was significantly increased at d26 and 33 compared to d5. Interestingly, the number of macrophages was significantly increased during the acute phase, whereas T cells were significantly increased in both the acute and chronic phase in C57BL/6 mice. Thus, our results show that chemokines are produced in a dynamic manner during colitis progression.
The intestine, with its large mucosal surface area, digests and absorbs food nutrients and mainta... more The intestine, with its large mucosal surface area, digests and absorbs food nutrients and maintains a beneficial microbial flora in the colon. Local protective immune responses against intestinal pathogens ensure the survival of the individual. These immune reactions are both specific and non-specific in nature. The intestinal epithelium is single-layered and constantly renewed with differentiating epithelial cells moving from the crypt to the luminal surface. Intraepithelial lymphocytes (IEL) are interspersed between the epithelial cells. Ulcerative colitis (UC) is a life-threatening chronic inflammation affecting colon.In this study three molecules belonging to the carcinoembryonic antigen (CEA) family, namely CEA proper, nonspecific cross-reacting antigen 50/90 (NCA 50/90) and biliary glycoprotein (BGP), were found to be specifically localized to the apical surface of colonic epithelial cells. Full expression of these molecules occurs when the cells reach the upper 1/3 of the crypts and are maintained on the mature cells at the luminal surface. Ultrastructurally, CEA, NCA50/90 and BGP are localized to microvesicles and microfilaments of the fuzzy coat/glycocalyx as well as to the microvilli of the epithelial cells. Their unique localization and documented bacterial binding capacities suggest that they have a role in innate immunity.Functional analysis of IEL in normal jejunum, ileum and colon revealed that IEL are in vivo activated T-lymphocytes expressing mRNA for the cytokines IL-1β, IL-2, IL-8, IFNγ and TNFα and that jejunal IEL have T-cell receptor (TCR)/CD3 dependent cytolytic capacity. As many as 10% of IEL actively produce IFNγ. CD4+TCRαβ+IEL, CD8+TCRαβ+IEL and CD4-CD8-TCRαβ+IEL all had a TH1/cytotoxic cytokine profile. IEL could be further stimulated in vitro to express IL-10, TNFβ and TGFβ1, to proliferate and to secrete IFNγ. Thus, active protection and/or regulation of the epithelium via cell-mediated immune reactions are prominent in the gut.UC colon was characterized by a marked lymphocyte infiltration in the lamina propria, 10-50 times the normal level. Most lymphocytes were present in follicle-like cell aggregates containing both T- and B-cells. An unexpected finding was that γδT-cells constituted about 15% of the cells in the aggregates. Such cells are only found intraepithelially in normal gut. γδT-cells of both the intestinal- (TCR-Vδ1/Vγ8) and blood type (TCR-Vδ2/Vγ9) were seen. T-cells in UC colon were activated but nonproliferating and had a down-regulated TCR/CD3 complex. RT-PCR and quantitative immunohistochemistry for cytokine mRNA (n=11) and protein respectively, revealed that the T-cells in UC colon did not produce IL-2, in marked contrast to T-cells in normal colon and to ileal T-cells from UC patients. This was a selective defect since TNFα, IFNγ, IL-1β, IL-8 and TGFβ1 were similarly expressed in normal colon. No TH2 cytokines were seen. Lamina propria leukocytes in UC colon expressed IL-6, a cytokine not found in normal colon. The epithelial cells of UC colon were activated expressing MHC class II antigens, heat shock proteins and the co-stimulatory molecule B7.1/CD80.Our study demonstrates that UC is an immunological disease. The immunopathological picture seen in UC colon probably reflects an inappropriate down-regulation of local immune responses perhaps due to a selective loss of the key cytokine IL-2 in a situation of extreme antigenic stress.
Dextran sulfate sodium (DSS)-induced colitis is one of the most frequently used rodent models for... more Dextran sulfate sodium (DSS)-induced colitis is one of the most frequently used rodent models for inflammatory bowel disease (IBD). The aim of this study was to validate the murine DSS-induced colitis model using four therapeutic agents for IBD. C57BL/6 mice were exposed to 3% DSS for 5days followed by 7-9 days of water (acute inflammation) or 20-31 days of water (chronic phase). Clinical symptoms, plasma and colonic inflammatory markers and histology were assessed for the efficacy of cyclosporine A (CsA), methotrexate or anti-IL-12p40 in acute colitis and of anti-IL-12p40 or an agonistic anti-CD3 antibody in chronic colitis. Cyclosporine A and anti-IL-12p40 (in the acute phase) and anti-CD3 (in the chronic phase) treatment attenuated local cytokine levels, improved clinical symptoms (CsA and anti-IL-12p40) and histology (CsA and anti-CD3). Further, anti-IL-12p40 treatment was partly efficacious in the chronic phase, whereas methotrexate showed no efficacy in the acute colitis. Thus, three of the current tested agents showed efficacy in the disease model, arguing that DSS-induced colitis can be used as a relevant model for the translation of mice data to human disease.
roton pump inhibitors (PPIs) are the first line Ptreatment for many gastrointestinal conditions a... more roton pump inhibitors (PPIs) are the first line Ptreatment for many gastrointestinal conditions and, since their introduction in the 1980s, PPIs have become the third most prescribed medication in United States. Moreover, PPIs, including omeprazole, are available over the counter in many countries; yet only few realize the increased risk of side effects including developing osteoporosis, electrolyte disorders and the increased risk of Clostridium difficile infection (CDI) via alterations in gut microbiota composition. In the current issue of Gastroenterology, a small open-label intervention trial performed by Freedberg et al aimed to study the effect of relative high dose of PPI (omeprazole) on the colonic microbiota and CDIassociated species in 12 otherwise healthy subjects. Fecal samples were collected twice at baseline (with 4 weeks in between to exclude interindividual differences). Subjects were then randomized to receive either 4 or 8 weeks of PPI followed by fecal sample collection. No effect upon PPI treatment was seen on intestinal microbial diversity; however, Enterococcae and streptococcal strains were significantly increased, whereas Clostridiales species were decreased. With PPI use, fecal bacterial DNA was enriched in genes associated with epithelial bacterial invasion. This study differs from other studies in that it did not find intestinal bacterial overgrowth with PPI use; others have found contradictory results with regard to bacterial overgrowth. Although there are some methodologic shortcomings of the current trial that might have severely impacted results (eg, no dietary intake monitoring, use of relatively high daily PPI doses), the fact that even in healthy subjects the intestinal microbiota are affected by PPI underscores the drastic effects of daily acid suppression on our intestinal bacteria. Moreover, these data provide evidence that regular usage of orally administered drugs (eg, PPI and statins) might affect gut microbiota composition, thus rendering our intestine more vulnerable for pathogen colonization including C difficile. Indeed, altered gut microbiota composition is causally related to CDI overgrowth, because introducing donor feces can eradicate CDI. What are the mechanisms regulated by PPIs on the microbiota that can lead a predisposition for CDI? It has been suggested that primary bile acids can act as germinants for C difficile spores, transforming them into growing bacteria. Certain colonic bacteria can indeed convert primary bile acids to secondary bile acids, and
Annual review of food science and technology, Mar 25, 2022
Diet exerts a major influence upon host immune function and the gastrointestinal microbiota. Alth... more Diet exerts a major influence upon host immune function and the gastrointestinal microbiota. Although components of the human diet (including carbohydrates, fats, and proteins) are essential sources of nutrition for the host, they also influence immune function directly through interaction with innate and cell-mediated immune regulatory mechanisms. Regulation of the microbiota community structure also provides a mechanism by which food components influence host immune regulatory processes. Here, we consider the complex interplay between components of the modern (Western) diet, the microbiota, and host immunity in the context of obesity and metabolic disease, inflammatory bowel disease, and infection.
ABSTRACTConflicting evidence exists on the association between consumption of non-steroidal anti-... more ABSTRACTConflicting evidence exists on the association between consumption of non-steroidal anti-inflammatory drugs (NSAIDs) and symptomatic worsening of inflammatory bowel disease (IBD). We hypothesise that the heterogeneous prevalence of pathobionts [e.g., adherent-invasiveEscherichiacoli (AIEC)], might explain this inconsistent NSAIDs/IBD correlation. UsingIL10-/-mice, we show aggravation of colitis in AIEC-colonised animals fed NSAID. This is accompanied by activation of the NLRP3 inflammasome, Caspase-8, apoptosis and pyroptosis; features not seen in mice exposed to AIEC or NSAID alone, revealing an AIEC/NSAID synergistic effect. Inhibition of NLRP3 or Caspase-8 activity ameliorated colitis, with reduction in NLRP3 inflammasome activation, cell death markers and activated T-cells and macrophages, improved histology and increased abundance ofClostridiumcluster XIVa species. Our findings provide mechanistic insights into how NSAID and an opportunistic gut-pathobiont can synergise to worsen IBD symptoms. Thus, targeting the NLRP3 inflammasome and Caspase-8 could be a potential therapeutic strategy in patients with NSAID-worsened inflammation.
Increased levels of chemokines and prostaglandins have been reported in patients with inflammator... more Increased levels of chemokines and prostaglandins have been reported in patients with inflammatory bowel disease, although their changes during disease development are less understood. The aim of this study was to investigate the local production of nine selected chemokines and prostaglandin E(2) (PGE(2)) to elucidate their role in colitis progression in BALB/c and C57BL/6 mice exposed to dextran sulphate sodium. The acute inflammation in both strains was accompanied by a significant up-regulation of CXCL1, CXCL2/3, CXCL10, CCL2, CCL4 and CCL22 and a downregulation of PGE(2). In the recovery phase in BALB/c, one-week post-DSS, PGE(2) levels were significantly increased with a concomitant downregulation of CXCL1, CXCL2/3, CXCL10, CCL2, and CCL4. In contrast, in C57BL/6 mice CXCL1, CXCL2/3, CXCL10, CCL2, CCL3 and CCL4 production remained high during the chronic phase, without any up-regulation of PGE(2). In addition, CCL5 was significantly increased at d26 and 33 compared to d5. Interestingly, the number of macrophages was significantly increased during the acute phase, whereas T cells were significantly increased in both the acute and chronic phase in C57BL/6 mice. Thus, our results show that chemokines are produced in a dynamic manner during colitis progression.
The intestine, with its large mucosal surface area, digests and absorbs food nutrients and mainta... more The intestine, with its large mucosal surface area, digests and absorbs food nutrients and maintains a beneficial microbial flora in the colon. Local protective immune responses against intestinal pathogens ensure the survival of the individual. These immune reactions are both specific and non-specific in nature. The intestinal epithelium is single-layered and constantly renewed with differentiating epithelial cells moving from the crypt to the luminal surface. Intraepithelial lymphocytes (IEL) are interspersed between the epithelial cells. Ulcerative colitis (UC) is a life-threatening chronic inflammation affecting colon.In this study three molecules belonging to the carcinoembryonic antigen (CEA) family, namely CEA proper, nonspecific cross-reacting antigen 50/90 (NCA 50/90) and biliary glycoprotein (BGP), were found to be specifically localized to the apical surface of colonic epithelial cells. Full expression of these molecules occurs when the cells reach the upper 1/3 of the crypts and are maintained on the mature cells at the luminal surface. Ultrastructurally, CEA, NCA50/90 and BGP are localized to microvesicles and microfilaments of the fuzzy coat/glycocalyx as well as to the microvilli of the epithelial cells. Their unique localization and documented bacterial binding capacities suggest that they have a role in innate immunity.Functional analysis of IEL in normal jejunum, ileum and colon revealed that IEL are in vivo activated T-lymphocytes expressing mRNA for the cytokines IL-1β, IL-2, IL-8, IFNγ and TNFα and that jejunal IEL have T-cell receptor (TCR)/CD3 dependent cytolytic capacity. As many as 10% of IEL actively produce IFNγ. CD4+TCRαβ+IEL, CD8+TCRαβ+IEL and CD4-CD8-TCRαβ+IEL all had a TH1/cytotoxic cytokine profile. IEL could be further stimulated in vitro to express IL-10, TNFβ and TGFβ1, to proliferate and to secrete IFNγ. Thus, active protection and/or regulation of the epithelium via cell-mediated immune reactions are prominent in the gut.UC colon was characterized by a marked lymphocyte infiltration in the lamina propria, 10-50 times the normal level. Most lymphocytes were present in follicle-like cell aggregates containing both T- and B-cells. An unexpected finding was that γδT-cells constituted about 15% of the cells in the aggregates. Such cells are only found intraepithelially in normal gut. γδT-cells of both the intestinal- (TCR-Vδ1/Vγ8) and blood type (TCR-Vδ2/Vγ9) were seen. T-cells in UC colon were activated but nonproliferating and had a down-regulated TCR/CD3 complex. RT-PCR and quantitative immunohistochemistry for cytokine mRNA (n=11) and protein respectively, revealed that the T-cells in UC colon did not produce IL-2, in marked contrast to T-cells in normal colon and to ileal T-cells from UC patients. This was a selective defect since TNFα, IFNγ, IL-1β, IL-8 and TGFβ1 were similarly expressed in normal colon. No TH2 cytokines were seen. Lamina propria leukocytes in UC colon expressed IL-6, a cytokine not found in normal colon. The epithelial cells of UC colon were activated expressing MHC class II antigens, heat shock proteins and the co-stimulatory molecule B7.1/CD80.Our study demonstrates that UC is an immunological disease. The immunopathological picture seen in UC colon probably reflects an inappropriate down-regulation of local immune responses perhaps due to a selective loss of the key cytokine IL-2 in a situation of extreme antigenic stress.
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Papers by Silvia Melgar