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Effects of dietary curcumin and rutin on colonic inflammation and gene expression in mdr1a-/- mice, a model of IBD

ABSTRACT: Damage of the intestinal epithelial barrier by xenobiotics or reactive oxygen species and a dysregulated immune response are both factors involved in the pathogenesis of inflammatory bowel diseases (IBD). Curcumin and rutin are polyphenolic compounds known to have anti-oxidant and anti-inflammatory activities, but their mechanism(s) of action are yet to be fully elucidated. Mdr1a-/- mice spontaneously develop intestinal inflammation, predominantly in the colon, with pathology similar to IBD, so this mouse model is relevant for studying diet-gene interactions and potential effects of foods on remission or development of IBD. This study tested whether the addition of curcumin or rutin to the diet would alleviate colonic inflammation in mdr1a-/- mice. Using whole-genome microarrays, the effect of dietary curcumin on gene expression in colon tissue was also investigated. Twelve mice were randomly assigned to each of three diets; control (AIN-76A), control + 0.2% curcumin or control + 0.1% rutin and monitored from the age of 7 to 24 weeks. Curcumin, but not rutin, significantly reduced histological signs of colonic inflammation in mdr1a-/- mice. Microarray and pathway analyses suggested that the effect of dietary curcumin on colon inflammation could be via an up-regulation of xenobiotic metabolism and a down-regulation of pro-inflammatory pathways probably mediated by PXR and PPARalpha activation of RXR. These results reveal the potential of global gene expression and pathway analyses to study and better understand the effect of foods in colonic inflammation. Keywords: Colonic inflammation, gene expression, curcumin, rutin, genome-wide microarrays

ORGANISM(S): Mus musculus

PROVIDER: GSE10684 | GEO | 2008/04/10

SECONDARY ACCESSION(S): PRJNA107673

REPOSITORIES: GEO

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Project description:Damage of the intestinal epithelial barrier by xenobiotics or reactive oxygen species and a dysregulated immune response are both factors involved in the pathogenesis of inflammatory bowel diseases (IBD). Curcumin and rutin are polyphenolic compounds known to have anti-oxidant and anti-inflammatory activities, but their mechanism(s) of action are yet to be fully elucidated. Mdr1a-/- mice spontaneously develop intestinal inflammation, predominantly in the colon, with pathology similar to IBD, so this mouse model is relevant for studying diet-gene interactions and potential effects of foods on remission or development of IBD. This study tested whether the addition of curcumin or rutin to the diet would alleviate colonic inflammation in mdr1a-/- mice. Using whole-genome microarrays, the effect of dietary curcumin on gene expression in colon tissue was also investigated. Twelve mice were randomly assigned to each of three diets; control (AIN-76A), control + 0.2% curcumin or control + 0.1% rutin and monitored from the age of 7 to 24 weeks. Curcumin, but not rutin, significantly reduced histological signs of colonic inflammation in mdr1a-/- mice. Microarray and pathway analyses suggested that the effect of dietary curcumin on colon inflammation could be via an up-regulation of xenobiotic metabolism and a down-regulation of pro-inflammatory pathways probably mediated by PXR and PPARï¡ activation of RXR. These results reveal the potential of global gene expression and pathway analyses to study and better understand the effect of foods in colonic inflammation. Experiment Overall Design: Twelve mice were randomly assigned to each of three diets; control (AIN-76A), control + 0â¢2% curcumin or control + 0â¢1% rutin and monitored from the age of 7 to 24 weeks. As only curcumin significantly reduced colonic HIS, comparison of the gene expression levels in colon was carried out using total RNA from colon tissue of four mdr1a-/- mice from the control group (high HIS) and four mdr1a-/- mice from the curcumin group (low HIS). A reference design with eight arrays was used for this comparison, where each individual RNA sample was hybridized in the array with the reference RNA, totalizing 4 biological replicates per treatment.

Project description:This study assessed gene expression changes associated with inflammation in the colon tissue of multi-drug resistance targeted mutation (Mdr1a-/-) mice, a model of human IBD. It also tested the anti-inflammatory potential of curcumin in the colon of these mice with a particular focus on the proteome. A colonic histological injury score was determined for each mouse to assess the level of colon inflammation in Mdr1a-/- mice, and to establish the effect of curcumin on inflammation. Insights into mechanisms of colonic inflammation in the Mdr1a-/- mice were gained using transcriptome (microarray) and proteome (2-D gel electrophoresis and LCMS protein identification) analyses. These data were compared to changes in the colon proteome in response to curcumin, and to previously described transcriptomic analyses [Nones et al, PMID: 18761777; GSE10684] in response to curcumin, in this model. A total of 24 male Mdr1a-/- mice, and 24 male FVB/N mice, purchased from Taconic (Hudson, NY, USA) at 4-5 weeks of age, were used for this study. 12 mice were randomly assigned to each of two different dietary groups: control (AIN-76A powdered diet), or curcumin (AIN-76A + 0.2% curcumin). At 21 and 24 weeks of age, mice were euthanized and colon samples taken for histological, microarray, and proteomics analyses. The total histology score (HIS) in the colon was determined according to previously described criteria. Total RNA was isolated using TRIzolM-BM-. reagent. Colon RNA from four Mdr1a-/- mice (with high HIS) on the control diet (i.e. AIN-76A powdered diet) was compared with colon RNA from four FVB/N mice with low HIS also on the control diet (i.e. AIN-76A powdered diet). All individual RNA samples were hybridized against a common reference RNA on separate slides. The reference RNA was prepared using equimolar RNA extracts from small intestine, colon, kidney and liver of normal healthy growing Swiss mice plus RNA extracts from Swiss mouse fetuses. These data were compared with previously reported transcriptomics analysis of colon RNA from the same four Mdr1a-/- mice on the AIN-76A diet (with high HIS) compared with colon RNA from four Mdr1a-/- mice on the curcumin diet (with low HIS; Nones et al 2009, PMID: 18761777)

Project description:Study 1: Transcriptomic profiles in colon tissue from inflammatory bowel diseases patients in relation to N-nitroso compound exposure and colorectal cancer risk Study 1: N-nitroso compounds (NOC) have been suggested to play a role in human cancer development but definitive evidence is still lacking. In this study we investigated gene expression modifications induced in human colon tissue in relation to NOC exposure to gain insight in the relevance of these compounds in human colorectal cancer (CRC) development. Since there are indications that inflammation stimulates endogenous NOC formation, the study population consisted of patients with inflammatory bowel disease (IBD) and irritable bowel syndrome patients as controls without inflammation. Strong transcriptomic differences were identified in colonic biopsies from IBD patients and compared to controls that enhance the understanding of IBD pathophysiology. However, fecal NOC levels were not increased in IBD patients, suggesting that inflammation did not stimulate NOC formation. By relating gene expression changes of all subjects to fecal NOC levels, we did, however, identify a NOC exposure-associated transcriptomic response that suggests that physiological NOC concentrations may induce genotoxic responses and chromatin modifications in human colon tissue, both of which are linked to carcinogenicity. In a network analysis, chromatin modifications were linked to 11 significantly modulated histone genes, pointing towards a possible epigenetic mechanism that may be relevant in comprehending the molecular basis of NOC-induced carcinogenesis. We conclude that NOC exposure is associated with gene expression modifications in the colon that may increase CRC risk in humans. Study 2: Red meat intake-induced increases in fecal water genotoxicity correlate with pro-carcinogenic gene expression changes in the human colon Study 2: Red meat consumption is associated with an increased colorectal cancer (CRC) risk, which may be due to an increased endogenous formation of genotoxic N-nitroso compounds (NOCs). To assess the impact of red meat intake on potential risk factors of CRC, we investigated the effect of a 7-day dietary red meat intervention in human subjects on endogenous NOC formation and fecal water genotoxicity in relation to transcriptomic changes induced in colonic tissue. In order to evaluate the potential effect of an inflamed colon on endogenous nitrosation, the study population consisted of inflammatory bowel disease (IBD) and irritable bowel syndrome (IBS) control subjects without inflammation. The intervention had no effect on fecal NOC formation but fecal water genotoxicity significantly increased in response to red meat intake. Since IBD patients showed no difference in fecal NOC formation or fecal water genotoxicity levels as compared to IBS controls, for transcriptomic analyses, all subjects were grouped together. Genes significantly correlating with the increase in fecal water genotoxicity were involved in biological pathways indicative of genotoxic effects, including modifications in DNA damage, cell cycle, and apoptosis pathways. Moreover, WNT signaling and nucleosome remodeling pathways were modulated that are known to play a part in the carcinogenic process in the human colon. These results are in line with a possible oxidative effect of dietary heme. We conclude that the gene expression changes identified in this study corroborate the genotoxic potential of diets high in red meat and point towards a possible risk of CRC development in humans. The study investigated transcription levels in human colon biopsies obtained during a colonoscopic exam in 32 subjects suffering from either inflammatory bowel disease (IBD) or irritable bowel syndrome (IBS). IBS patients served as control patients for comparison with IBD patients (see Study 1). 12 of these patients (6 IBD and 6 IBS) also followed a 7-day diet high in red meat (300 grams/day) after which a second colonscopic exam was performed to obtain colon biopsies to investigate the effect of the red meat intervention (Study 2). For each subject, cRNA copies of mRNA isolated from the colon biopsies were labeled with one dye (Cy3) and each sample was hybridized on a separate array. One replicate per subject or before/after red meat intervention (so 44 arrays in total, i.e. 20 before patients and 12 before and after patients).

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Effects of dietary curcumin and rutin on colonic inflammation and gene expression in mdr1a-/- mice, a model of IBD

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