Long-term intake of dietary fat and risk of ulcerative colitis and Crohn's disease

A Potential Role of Salmonella Infection in the Onset of Inflammatory Bowel Diseases

Inflammatory bowel disease (IBD) includes a set of pathologies that result from a deregulated immune response that may affect any portion of the gastrointestinal tract. The most prevalent and defined forms of IBD are Crohn’s disease and ulcerative colitis. Although the etiology of IBD is not well defined, it has been suggested that environmental and genetic factors contribute to disease development and that the interaction between these two factors can trigger the pathology. Diet, medication use, vitamin D status, smoking, and bacterial infections have been proposed to influence or contribute to the onset or development of the disease in susceptible individuals. The infection with pathogenic bacteria is a key factor that can influence the development and severity of this disease. Here, we present a comprehensive review of studies performed in human and mice susceptible to IBD, which supports the notion that infection with bacterial pathogens, such as Salmonella, could promote the onset of IBD due to permanent changes in the intestinal microbiota, disruption of the epithelial barrier and alterations of the intestinal immune response after infection.

Diet as a Trigger or Therapy for Inflammatory Bowel Diseases

The most common question asked by patients with inflammatory bowel disease (IBD) is, "Doctor, what should I eat?" Findings from epidemiology studies have indicated that diets high in animal fat and low in fruits and vegetables are the most common pattern associated with an increased risk of IBD. Low levels of vitamin D also appear to be a risk factor for IBD. In murine models, diets high in fat, especially saturated animal fats, also increase inflammation, whereas supplementation with omega 3 long-chain fatty acids protect against intestinal inflammation. Unfortunately, omega 3 supplements have not been shown to decrease the risk of relapse in patients with Crohn's disease. Dietary intervention studies have shown that enteral therapy, with defined formula diets, helps children with Crohn's disease and reduces inflammation and dysbiosis. Although fiber supplements have not been shown definitively to benefit patients with IBD, soluble fiber is the best way to generate short-chain fatty acids such as butyrate, which has anti-inflammatory effects. Addition of vitamin D and curcumin has been shown to increase the efficacy of IBD therapy. There is compelling evidence from animal models that emulsifiers in processed foods increase risk for IBD. We discuss current knowledge about popular diets, including the specific carbohydrate diet and diet low in fermentable oligo-, di-, and monosaccharides and polyols. We present findings from clinical and basic science studies to help gastroenterologists navigate diet as it relates to the management of IBD.

The Importance and Challenges of Dietary Intervention Trials for Inflammatory Bowel Disease

Inflammatory bowel disease is believed to be caused by a combination of genetic and environmental stimuli such as our diet. Diets high in meat and fats and low in fruits and vegetables have been associated with new-onset inflammatory bowel disease. This has triggered interest in using dietary modification as a treatment. The 3 principle models of dietary intervention are supplementation with selected dietary components, exclusion of selected dietary components, or use of dietary formulas in place of a normal diet. Despite the high level of interest in dietary interventions as a treatment for inflammatory bowel disease, few well-designed clinical trials have been conducted to firmly establish the optimal diet to induce or maintain remission. This may be in part related to the challenges of conducting dietary intervention trials. This review examines these challenges and potential approaches to be used in dietary intervention trials.

HADHA, the alpha subunit of the mitochondrial trifunctional protein, is involved in long-chain fatty acid-induced autophagy in intestinal epithelial cells

Genome-wide association studies have identified autophagy-related susceptibility genes for inflammatory bowel disease (IBD); however, whether autophagy regulators can be utilized as therapeutic targets remains unclear. To identify novel microtubule-associated protein 1 light chain 3 (LC3)-interacting proteins in intestinal epithelial cells (IECs), we isolated primary IECs from green fluorescent protein (GFP)-LC3 mice. We performed immunoprecipitation with a GFP antibody and then analyzed co-immunoprecipitates by mass spectrometry. HADHA was identified as an LC3-interacting protein from primary IECs. The HADHA gene encodes the alpha subunit of the mitochondrial trifunctional protein. Given that HADHA catalyzes the last three steps of mitochondrial beta-oxidation of long-chain fatty acids, we investigated whether long-chain fatty acids induce autophagy in IECs. We found that palmitic acid induced autophagy in DLD-1, HT29, and HCT116 cells. HADHA was expressed in not only the mitochondria but also the cytosol. LC3 puncta co-localized with HADHA, which were enhanced by palmitic acid stimulation. However, LC3 puncta did not co-localize with Tom20, suggesting that HADHA was induced to associate with LC3 puncta at sites other than the mitochondria. Thus, HADHA may have extra-mitochondrial functions. Furthermore, we found that palmitic acid induced cell death in IECs, which was accelerated by bafilomycin A and chloroquine. These findings suggested that palmitic acid-induced autophagy supports the survival of IECs. Taken together, these results suggested that HADHA is involved in long-chain fatty acid-induced autophagy in IECs, thus providing new insights into the pathology of IBD and revealing novel therapeutic targets of IBD.

Effects of Herb-Partitioned Moxibustion on the miRNA Expression Profiles in Colon from Rats with DSS-Induced Ulcerative Colitis

Objective. This study explored the mechanism of herb-partitioned moxibustion (HM) on dextran sulfate sodium- (DSS-) induced ulcerative colitis (UC) from the miRNA perspective. Methods. Rats were randomly divided into 3 groups [normal control (NC) group, UC model (UC) group, and herb-partitioned moxibustion (UCHM) group]. The UC and UCHM groups were administered 4% DSS for 7 days. The UCHM group received HM at the Tianshu (bilateral, ST25). The effect of HM on UC was observed and the miRNA expression profile in the colon tissues was analyzed. Results. Compared with the UC group, the body weights were significantly higher in the UCHM group on day 14 (P < 0.001); the macroscopic colon injury scores and microscopic histopathology scores in the UCHM group decreased (P < 0.05); and there were 15 differentially expressed miRNAs in the UCHM group. The changes in miR-184 and miR-490-5p expression levels on the UC were reversed by HM intervention. Validation using qRT-PCR showed that two miRNAs expression trend was consistent with the sequencing results. Conclusion. HM at ST25 might regulate miR-184 and miR-490-5p expression, act on the transcription of their target genes to regulate inflammatory signaling pathways, and attenuate inflammation and tissue injury in the colons of rats with DSS-induced UC.

Fat intake and risk of ulcerative colitis: Systematic review and dose-response meta-analysis of epidemiological studies

BACKGROUND AND AIM

Fat intake is generally thought as a risk factor for onset of ulcerative colitis (UC), while epidemiological data had been controversial. This study aimed to evaluate the role of fat intake in the development of UC.

METHODS

Comprehensive search in PubMed and Embase was conducted to identify all relevant studies, and the role of fat intake in the development of UC was quantitatively assessed by dose-response meta-analysis.

RESULTS

Nine studies (four case-control and five prospective cohort) were indentified with a total of 966 UC cases and 171 589 controls. No evidence of a nonlinear dose-response association was found between fat intake and UC risk. Overall, the summary relative risks (RR) for per 30 g increment/day were 1.023 (95%confidence interval [CI]: 0.963-1.087; I²  = 24%; n = 6) for total fat intake, 1.063 (95%CI: 0.845-1.337; I²  = 44.5%; n = 4) for saturated fat intake, 1.214 (95%CI: 0.911-1.618; I²  = 63.1%; n = 4) for monounsaturated fat (MUFA) intake, and 1.247 (95%CI: 0.948-1.640; I²  = 25.4%; n = 4) for polyunsaturated fat (PUFA) intake, respectively. Subgroup and sensitivity analyses showed inconsistent results on PUFA intake, which was significantly related with UC risk after adjusting for smoking (RR: 1.617, 95%CI: 1.045-2.502; I²  = 0%; n = 3). For PUFA and MUFA subtypes, no subtypes were significantly associated with UC risk (P > 0.05), and only docosahexaenoic acid showed a potential protective effect in the development of UC (RR for the highest versus lowest intake level: 0.642, 95%CI: 0.403-1.024; I²  = 34.4%; n = 3) CONCLUSIONS: This meta-analysis suggested a lack of association between fat intake and UC risk, and large-scale prospective designed studies are warranted to confirm our findings.

ESPEN guideline: Clinical nutrition in inflammatory bowel disease

INTRODUCTION

The ESPEN guideline presents a multidisciplinary focus on clinical nutrition in inflammatory bowel disease (IBD).

METHODOLOGY

The guideline is based on extensive systematic review of the literature, but relies on expert opinion when objective data were lacking or inconclusive. The conclusions and 64 recommendations have been subject to full peer review and a Delphi process in which uniformly positive responses (agree or strongly agree) were required.

RESULTS

IBD is increasingly common and potential dietary factors in its aetiology are briefly reviewed. Malnutrition is highly prevalent in IBD - especially in Crohn's disease. Increased energy and protein requirements are observed in some patients. The management of malnutrition in IBD is considered within the general context of support for malnourished patients. Treatment of iron deficiency (parenterally if necessary) is strongly recommended. Routine provision of a special diet in IBD is not however supported. Parenteral nutrition is indicated only when enteral nutrition has failed or is impossible. The recommended perioperative management of patients with IBD undergoing surgery accords with general ESPEN guidance for patients having abdominal surgery. Probiotics may be helpful in UC but not Crohn's disease. Primary therapy using nutrition to treat IBD is not supported in ulcerative colitis, but is moderately well supported in Crohn's disease, especially in children where the adverse consequences of steroid therapy are proportionally greater. However, exclusion diets are generally not recommended and there is little evidence to support any particular formula feed when nutritional regimens are constructed.

CONCLUSIONS

Available objective data to guide nutritional support and primary nutritional therapy in IBD are presented as 64 recommendations, of which 9 are very strong recommendations (grade A), 22 are strong recommendations (grade B) and 12 are based only on sparse evidence (grade 0); 21 recommendations are good practice points (GPP).

miR-301a promotes intestinal mucosal inflammation through induction of IL-17A and TNF-α in IBD

OBJECTIVE

MicroRNA (miR)-301a is known to be involved in the tumourigenesis and pathogenesis of several autoimmune diseases, but it remains unclear whether miR-301a is associated with the pathogenesis of IBD.

METHODS

miR-301a expression was assessed in peripheral blood mononuclear cells (PBMC) and inflamed mucosa of patients with IBD by quantitative real-time-PCR. Peripheral blood CD4+ T cells were transduced with lentivirus-encoding pre-miR-301a (LV-miR-301a) or a reverse complementary sequence of miR-301a (LV-anti-miR-301a), and their differentiation and activation were investigated in vitro. Antisense miR-301a was administered into mice during trinitrobenzene sulphonic acid (TNBS)-induced colitis to determine its role in colitis.

RESULTS

miR-301a expression was significantly upregulated in PBMC and inflamed mucosa of patients with IBD compared with healthy controls. Stimulation with tumour necrosis factor-α (TNF-α) significantly enhanced miR-301a expression in IBD CD4+ T cells, which was markedly reversed by anti-TNF-α mAb (Infliximab) treatment. Transduction of LV-miR-301a into CD4+ T cells from patients with IBD promoted the Th17 cell differentiation and TNF-α production compared with the cells with expression of LV-anti-miR-301a. SNIP1 as a functional target of miR-301a was reduced in miR-301a expression but increased in LV-anti-miR-301a expression. Knockdown of SNIP1 could enhance Th17 cell differentiation. Furthermore, intracolonical administration of antisense miR-301a in TNBS-induced mouse colitis model significantly decreased numbers of interleukin (IL)-17A+ cells and amounts of pro-inflammatory cytokines (eg, IL-17A, TNF-α) in inflamed colon.

CONCLUSIONS

Our data reveal a novel mechanism in which the elevated miR-301a in PBMC and inflamed mucosa of IBD promotes Th17 cell differentiation through downregulation of SNIP1. Blockade of miR-301a in vivo may serve as a novel therapeutic approach in the treatment of IBD.

Docosahexaenoyl serotonin, an endogenously formed n-3 fatty acid-serotonin conjugate has anti-inflammatory properties by attenuating IL-23-IL-17 signaling in macrophages

Conjugates of fatty acids and amines, including endocannabinoids, are known to play important roles as endogenous signaling molecules. Among these, the ethanolamine conjugate of the n-3 poly unsaturated long chain fatty acid (PUFA) docosahexaenoic acid (22:6n-3) (DHA) was shown to possess strong anti-inflammatory properties. Previously, we identified the serotonin conjugate of DHA, docosahexaenoyl serotonin (DHA-5-HT), in intestinal tissues and showed that its levels are markedly influenced by intake of n-3 PUFAs. However, its biological roles remain to be elucidated. Here, we show that DHA-5-HT possesses potent anti-inflammatory properties by attenuating the IL-23-IL-17 signaling cascade in lipopolysaccharide (LPS)-stimulated RAW264.7 macrophages. Transcriptome analysis revealed that DHA-5-HT down-regulates LPS-induced genes, particularly those involved in generating a CD4+ Th17 response. Hence, levels of PGE2, IL-6, IL-1β, and IL-23, all pivotal macrophage-produced mediators driving the activation of pathogenic Th17 cells in a concerted way, were found to be significantly suppressed by concentrations as low as 100-500nM DHA-5-HT. Furthermore, DHA-5-HT inhibited the ability of RAW264.7 cells to migrate and downregulated chemokines like MCP-1, CCL-20, and gene-expression of CCL-22 and of several metalloproteinases. Gene set enrichment analysis (GSEA) suggested negative overlap with gene sets linked to inflammatory bowel disease (IBD) and positive overlap with gene sets related to the Nrf2 pathway. The specific formation of DHA-5-HT in the gut, combined with increasing data underlining the importance of the IL-23-IL-17 signaling pathway in the etiology of many chronic inflammatory diseases merits further investigation into its potential as therapeutic compound in e.g. IBD or intestinal tumorigenesis.

Polyunsaturated Fatty Acids and Their Derivatives: Therapeutic Value for Inflammatory, Functional Gastrointestinal Disorders, and Colorectal Cancer

Polyunsaturated fatty acids (PUFAs) are bioactive lipids which modulate inflammation and immunity. They gained recognition in nutritional therapy and are recommended dietary supplements. There is a growing body of evidence suggesting the usefulness of PUFAs in active therapy of various gastrointestinal (GI) diseases. In this review we briefly cover the systematics of PUFAs and their metabolites, and elaborate on their possible use in inflammatory bowel disease (IBD), functional gastrointestinal disorders (FGIDs) with focus on irritable bowel syndrome (IBS), and colorectal cancer (CRC). Each section describes the latest findings from in vitro and in vivo studies, with reports of clinical interventions when available.

Combination of metformin and VSL#3 additively suppresses western-style diet induced colon cancer in mice

Western-style diet (WD) and dysbiosis are known to be associated with colonic inflammation, which contributes to carcinogenesis. Metformin (Met) exerts anti-inflammatory effects to induce AMP-activated protein kinase (AMPK), resulting in suppressed protein synthesis and reduced cell proliferation. Probiotic VSL#3 (V) modifies microbial composition. We investigated the chemopreventive mechanisms of Met and V in WD-induced colitis-associated colon carcinogenesis. Male BALB/c mice were randomly divided into five groups: a control diet (CD) group, WD group, WD+ Met (250mg/kg/day) group, WD+V (1.3 million bacteria/day) group, and WD+Met+V group. All mice were exposed to azoxymethane (10mg/kg) followed by 2% dextran sodium sulfate (DSS) for 7 days. Using HCT-116 human colon cancer cell line, expression of AMPK, extracellular signal-regulated kinase (ERK), cyclin D1, and Bcl-2 was investigated and cell cycle arrest was assessed. WD enhanced the severity of colitis and tumor growth compared with CD. The combination of Met and V significantly ameliorated colitis and tumor growth by inhibiting macrophage infiltration and maintaining epithelial integrity. In vitro assays showed that the combination therapy promoted late apoptosis by inhibiting cyclin D1 and Bcl-2 and activating pro-apoptotic ERK. A combination therapy with Met and V attenuates tumor growth in a mouse model of WD-induced colitic cancer, suggesting that this strategy could be useful for the chemoprevention of colon cancer.

Translating nutritional immunology into drug development for inflammatory bowel disease

PURPOSE OF REVIEW

To highlight recent advances in the understanding of nutritional immunology and in the development of novel therapeutics for inflammatory bowel disease (IBD).

RECENT FINDINGS

We highlight the variety of factors that contribute to the interaction of the immune system and nutrition including the microbiome and the nervous system stimulation of the gut. We describe the potential for therapeutic development in IBD. Further, we review the cellular metabolic effects on immune activation and promising therapeutic targets. Finally, we show how the progression of understanding the role of lanthionine synthetase C-like 2 has encompassed both nutritional and therapeutic advances and led to the development of novel oral small molecule therapeutics for IBD.

SUMMARY

Nutritional immunology and drug development research centered around immunoregulatory pathways can provide safer and more effective drugs while accelerating the path to cures.

IBD: In Food We Trust

BACKGROUND AND AIMS

Both science and patients associate diet with inflammatory bowel disease [IBD]. There is no doubt that links between IBD and diet are numerous, based on both epidemiological studies and experimental studies. However, scientific evidence to support dietary advice is currently lacking, and dietary counselling for IBD patients is often limited in clinical practice to the improvement of nutrient intake. This review aimed to focus on both patient's beliefs about and molecular mechanisms for crosstalk between nutrients and inflammation.

METHODS

A literature search using PubMed was performed to identify relevant studies on diet and/or nutrients and their role in IBD. Pubmed [from inception to January 20, 2016] was searched using the terms: 'Crohn', 'colitis',' intestinal epithelial cells', and a list of terms relating to diet or numerous specific nutrients. Terms associated with nutrients were individually tested in the context of IBD. Reference lists from studies selected were manually searched to identify further relevant reports. Manuscripts about diet in the context of IBD from basic science, epidemiological studies, or clinical trials were selected and reviewed. Only articles published in English were included.

RESULTS

Epidemiological studies highlight the key role of diet in IBD development, and many IBD patients report diet as a triggering factor in relapse of disease. In addition, we present research on the impact of nutrients on innate immunity.

CONCLUSION

Diet may offer an alternative approach to restoring deficient innate immunity in IBD, and this may be the scientific rationale for providing dietary counselling for IBD patients.

Oral Contraceptive Use and Risk of Ulcerative Colitis Progression: A Nationwide Study

OBJECTIVES

Oral contraceptive (OC) use has been consistently linked to increased risk of inflammatory bowel disease. Nonetheless, a specific role of OC in the natural history of ulcerative colitis (UC) is unknown.

METHODS

We identified 6,104 incident female UC cases aged 16-51 years at diagnosis from the Swedish National Patient Register starting in January of 2003. Information on current OC use was obtained from the Prescribed Drug Register starting in July of 2005. We followed cases through December of 2014 for primary outcome defined as first UC-related surgery, and the secondary outcomes defined by recipient of the first prescription of oral steroids or anti-tumor necrosis factor (anti-TNF) use. We used Cox proportional hazard modeling with time-varying covariates to estimate multivariable-adjusted hazard ratio (aHR) and 95% confidence interval (CI).

RESULTS

Over 31,421 person-years of follow up, we observed 162 cases of UC-related surgery. Compared with nonusers, current and past use of OC were not significantly associated with risk of UC-related surgery (aHR=0.79; 95% CI, 0.52-1.18; and aHR=0.74, 95% CI, 0.46-1.18, respectively). The association did not appear to be modified by type of OC use (progestin-only vs. combination of progestin and estrogen), longer duration of use, or higher number of dispensed prescriptions (All P_trend>0.28). Similarly, longer use or higher cumulative number of OC prescriptions were not associated with increased risk of receiving a steroid prescription (P_trend=0.68 and 0.63, respectively). In exploratory analyses restricted to Stockholm county, current OC use was not associated with increased risk of receiving anti-TNF therapy (aHR=0.83, 95% CI, 0.59-1.18).

CONCLUSIONS

In a large nationwide registry of UC patients, we found no association between OC use and UC progression. Our data offer reassurance regarding the safety of OC assessed by its effect on risk of surgery and steroid or anti-TNF use in women with established UC.

Faecal calprotectin: factors affecting levels and its potential role as a surrogate marker for risk of development of Crohn's Disease

Background

Faecal calprotectin (FC) is one of the most widely used non-invasive tests for the diagnosis and assessment of Crohn’s disease (CD) activity. Despite this, factors other than disease activity which affect levels have not been extensively reviewed. This is of importance when using FC in the diagnostic setting but also may be of utility in studying the aetiology of disease.

Objectives

Our review outlines environmental risk factors that affect FC levels influencing diagnostic accuracy and how these may be associated with risk of developing CD. FC as a surrogate marker could be used to validate risk factors established in case control studies where prospective studies are not feasible. Proof of this concept is provided by our identification of obesity as being associated with elevated FC, our subsequent confirmation of obesity as risk factor for CD and the subsequent verification in prospective studies, as well as associations of lack of physical activity and dietary fibre intake with elevated FC levels and their subsequent confirmation as risk factors in prospective studies.

Conclusion

We believe that FC is likely to prove a useful surrogate marker for risk of developing CD. This review has given a theoretical basis for considering the epidemiological determinants of CD which to date has been missing.

Zinc intake and risk of Crohn’s disease and ulcerative colitis: a prospective cohort study

BACKGROUND

Diet plays a role in the pathogenesis of Crohn’s disease (CD) and ulcerative colitis (UC). Dietary zinc may influence risk of disease through effects on autophagy, innate and adaptive immune response and maintenance of the intestinal barrier.

METHODS

We analysed data from 170 776 women from the Nurses Health Study I and Nurses Health Study II, who were followed for 26 years. Zinc intake was assessed using semi-quantitative food frequency questionnaires administered every 4 years. Incident CD and UC were ascertained by medical record review. Cox proportional hazards models adjusting for potential confounders determined the independent association between zinc intake and incident disease.

RESULTS

Over 3 317 550 person-years (p-y) of follow-up, we identified 269 incident cases of CD and 338 incident cases of UC. Zinc intake ranged from 9 mg/day in the lowest quintile to 27 mg/day in the highest quintile. Compared with women with the lowest quintile of intake, the multivariate hazard ratios (HR) for CD were 0.92 [95% confidence interval (CI), 0.65 – 1.29) for women in the second quintile of intake, 0.60 (95% CI, 0.40 – 0.89) for the third quintile, 0.57 (95% CI, 0.38 – 0.86) for fourth quintile and 0.74 (95% CI, 0.50 – 1.10) for the highest quintile (Ptrend = 0.003). The association was stronger for dietary zinc (HR 0.63, 95% CI, 0.43 – 0.93, comparing extreme quintiles) than for zinc intake from supplements. Neither dietary nor supplemental zinc modified risk of UC.

CONCLUSIONS

In two large prospective cohorts of women, intake of zinc was inversely associated with risk of CD but not UC.

Periodontal manifestations of inflammatory bowel disease: emerging epidemiologic and biologic evidence

Inflammatory bowel disease and periodontitis are both described as a disproportionate mucosal inflammatory response to a microbial environment in susceptible patients. Moreover, these two conditions share major environmental and lifestyle-related risk factors. Despite this intriguing pathogenic parallel, large-scale studies and basic research have only recently considered periodontal outcomes as relevant data. There are mounting and consistent arguments, from recent epidemiologic studies and animal models, that these two conditions might be related. This article is a comprehensive and critical up-to-date review of the current evidence and future prospects in understanding the biologic and epidemiologic relationships between periodontal status and inflammatory bowel disease.

Progress in Our Understanding of the Gut Microbiome: Implications for the Clinician

The investigation of the role of the microbial communities of our gastrointestinal tract (microbiota) has accelerated dramatically in recent years thanks to rapid developments in the technologies that allow us to fully enumerate and evaluate the full complement of bacterial species and strains that normally inhabit the gut. Laboratory studies in a range of inventive animal models continue to provide insights into the role of the microbiota in health and to generate plausible hypotheses relating to its potential involvement in the pathogenesis of human disease. Studies of the composition of human gut microbiota continue to accumulate but their interpretation needs to be tempered by an appreciation of the limitations of single-point-in-time studies of fecal samples from small study populations. Nevertheless, clinically important examples of a central role for microbiota-host interactions in disease pathogenesis have emerged and many more have been postulated but await confirmation in appropriately powered and conducted studies.

High fat diet exacerbates dextran sulfate sodium induced colitis through disturbing mucosal dendritic cell homeostasis

Epidemiological studies have shown that fat rich western diet contributes to the high incidence of inflammatory bowel disease (IBD). Moreover, accumulated data indicated that fat dietary factor might promote the change of the composition and metabolism in commensal flora. But, the exact mechanisms for fatty diet in gut inflammation are not well demonstrated. In this study, we found that high fat diet (HFD) promoted inflammation and exacerbated the disease severity of dextran sulfate sodium (DSS) induced colitis in mice. Compared with low fat diet (LFD)/DSS mice, shorter colon length, more epithelial loss and crypt destruction and more Gr-1⁺ myeloid inflammatory cells infiltration in colons were observed in HFD/DSS cohorts. Interestingly, such HFD mediated inflammation accompanied with the dys-regulation of hematopoiesis, and more hematopoiesis stem and progenitor cells were detected in colon and spleen. We further analyzed the effects of HFD and DSS treatment on mucosal DC subsets, and found that DSS treatment in LFD mice mainly dramatically increased the percentage of CD11c⁺CD103^-CD11b⁺ DCs in lamina propria (LP). While, in HFD/DSS mice, HFD pre-treatment not only increased the percentage of CD11c⁺CD103^-CD11b⁺ DCs, but also decreased CD11c⁺CD103⁺CD11b⁺ in both LP and mesenteric lymph nodes (MLN) in mice with colitis. This disequilibrium of mucosal dendritic cells in HFD/DSS mice may depend on the reduced levels of buytrate and retinoic acid. Thus, this study declared the effects of HFD on gut microenviroment, and further indicated its potential role in the development of DSS induced colitis.

Diet, gut microbes, and the pathogenesis of inflammatory bowel diseases

The rising incidence of inflammatory bowel diseases in recent decades has notably paralleled changing lifestyle habits in Western nations, which are now making their way into more traditional societies. Diet plays a key role in IBD pathogenesis, and there is a growing appreciation that the interaction between diet and microbes in a susceptible person contributes significantly to the onset of disease. In this review, we examine what is known about dietary and microbial factors that promote IBD. We summarize recent findings regarding the effects of diet in IBD epidemiology from prospective population cohort studies, as well as new insights into IBD-associated dysbiosis. Microbial metabolism of dietary components can influence the epithelial barrier and the mucosal immune system, and understanding how these interactions generate or suppress inflammation will be a significant focus of IBD research. Our knowledge of dietary and microbial risk factors for IBD provides important considerations for developing therapeutic approaches through dietary modification or re-shaping the microbiota. We conclude by calling for increased sophistication in designing studies on the role of diet and microbes in IBD pathogenesis and disease resolution in order to accelerate progress in response to the growing challenge posed by these complex disorders.

WISP1 Is Increased in Intestinal Mucosa and Contributes to Inflammatory Cascades in Inflammatory Bowel Disease

Inflammatory bowel disease (IBD) is mainly characterized by intestinal tissue damage, which is caused by excessive autoimmune responses poorly controlled by corresponding regulatory mechanisms. WISP1, which belongs to the CCN protein family, is a secreted matricellular protein regulating several inflammatory pathways, such as Wnt/β-catenin pathway, and has been reported in several diseases including cancer. Here we examined the expression, regulatory mechanisms, and functions of WISP1 in IBD. WISP1 mRNA and protein expression was upregulated in colonic biopsies and lamina propria mononuclear cells (LPMC) of IBD patients compared with those of healthy controls. Tumor necrosis factor- (TNF-) α induced WISP1 expression in LPMC from healthy controls. Consistently, WISP1 mRNA expression was downregulated in colonic biopsies from IBD patients who had achieved clinical remission with infliximab (IFX). Furthermore, WISP1 expression was also found to be increased in colons from 2,4,6-trinitrobenzenesulfonic acid- (TNBS-) induced mice compared with those from control mice. Further studies confirmed that administration of rWISP1 could aggravate TNBS-induced colitis in vivo. Therefore, we concluded that WISP1 is increased in IBD and contributes to the proinflammatory cascades in the gut.

Food, nutrients and nutraceuticals affecting the course of inflammatory bowel disease

Inflammatory bowel diseases (ulcerative colitis; Crohn's disease) are debilitating relapsing inflammatory disorders affecting the gastrointestinal tract, with deleterious effect on quality of life, and increasing incidence and prevalence. Mucosal inflammation, due to altered microbiota, increased intestinal permeability and immune system dysfunction underlies the symptoms and may be caused in susceptible individuals by different factors (or a combination of them), including dietary habits and components. In this review we describe the influence of the Western diet, obesity, and different nutraceuticals/functional foods (bioactive peptides, phytochemicals, omega 3-polyunsaturated fatty acids, vitamin D, probiotics and prebiotics) on the course of IBD, and provide some hints that could be useful for nutritional guidance. Hopefully, research will soon offer enough reliable data to slow down the spread of the disease and to make diet a cornerstone in IBD therapy.

Nutrition in Pediatric Inflammatory Bowel Disease: From Etiology to Treatment. A Systematic Review

Nutrition is involved in several aspects of pediatric inflammatory bowel disease (IBD), ranging from disease etiology to induction and maintenance of disease. With regards to etiology, there are pediatric data, mainly from case-control studies, which suggest that some dietary habits (for example consumption of animal protein, fatty foods, high sugar intake) may predispose patients to IBD onset. As for disease treatment, exclusive enteral nutrition (EEN) is an extensively studied, well established, and valid approach to the remission of pediatric Crohn’s disease (CD). Apart from EEN, several new nutritional approaches are emerging and have proved to be successful (specific carbohydrate diet and CD exclusion diet) but the available evidence is not strong enough to recommend this kind of intervention in clinical practice and new large experimental controlled studies are needed, especially in the pediatric population. Moreover, efforts are being made to identify foods with anti-inflammatory properties such as curcumin and long-chain polyunsaturated fatty acids n-3, which can possibly be effective in maintenance of disease. The present systematic review aims at reviewing the scientific literature on all aspects of nutrition in pediatric IBD, including the most recent advances on nutritional therapy.

Inflammatory Potential of Diet and Risk of Ulcerative Colitis in a Case-Control Study from Iran

Diet and inflammation have been suggested to be important risk factors for ulcerative colitis (UC). In this case-control study conducted in Iran, we examined the ability of the dietary inflammatory index (DII) to predict UC. This study included 62 UC cases and 124 controls hospitalized for acute non-neoplastic diseases. The DII was computed based on dietary intake assessed by a previously validated food frequency questionnaire. Multivariable logistic regression models were used to estimate odds ratios (ORs) and the DII was analyzed as both continuous and as tertiles. Energy was adjusted using the residual method. Subjects with higher DII scores (i.e., with a more pro-inflammatory diet) had a higher risk of UC, with the DII being used as both a continuous variable (OR(continuous) 1.55, 95% confidence interval (CI) 1.04-2.32; one unit increase corresponding to ≈8% of its range in the current study) and as tertiles (OR(tertile3vstertile1) 2.58, 95% CI 1.03-6.48, P(trend)| = |0.04). These results indicate that a pro-inflammatory diet is associated with increased risk of UC.

Diet therapy for inflammatory bowel diseases: The established and the new

Although patients with inflammatory bowel diseases (IBD) have a strong interest in dietary modifications as part of their therapeutic management, dietary advice plays only a minor part in published guidelines. The scientific literature shows that dietary factors might influence the risk of developing IBD, that dysbiosis induced by nutrition contributes to the pathogenesis of IBD, and that diet may serve as a symptomatic treatment for irritable bowel syndrome-like symptoms in IBD. The role of nutrition in IBD is underscored by the effect of various dietary therapies. In paediatric patients with Crohn’s disease (CD) enteral nutrition (EN) reaches remission rates similar to steroids. In adult patients, however, EN is inferior to corticosteroids. EN is not effective in ulcerative colitis (UC). Total parenteral nutrition in IBD is not superior to steroids or EN. The use of specific probiotics in patients with IBD can be recommended only in special clinical situations. There is no evidence for efficacy of probiotics in CD. By contrast, studies in UC have shown a beneficial effect in selected patients. For patients with pouchitis, antibiotic treatment followed by probiotics, like VSL#3 or Lactobacillus GG, is effective. When probiotics are used, the risk of bacterial translocation and subsequent bacteremia has to be considered. More understanding of the normal intestinal microflora, and better characterization of probiotic strains at the phenotypic and genomic levels is needed as well as clarification of the mechanisms of action in different clinical settings. A FODMAP reduced diet may improve symptoms in IBD.

Influence of environmental factors in the development of inflammatory bowel diseases

Idiopathic inflammatory bowel diseases (IBD), Crohn's disease (CD) and ulcerative colitis (UC), are multifactorial diseases that are manifested after disruption of a genetic predisposed individual and its intestinal microflora through an environmental stimulus. Urbanization and industrialization are associated with IBD. Epidemiological data, clinical observations and family/immigrants studies indicate the significance of environmental influence in the development of IBD. Some environmental factors have a different effect on the subtypes of IBD. Smoking and appendectomy is negatively associated with UC, but they are aggravating factors for CD. A westernized high fat diet, full of refined carbohydrates is strongly associated with the development of IBD, contrary to a high in fruit, vegetables and polyunsaturated fatty acid-3 diet that is protective against these diseases. High intake of nonsteroidal antiinflammatory drug and oral contraceptive pills as well as the inadequacy of vitamin D leads to an increased risk for IBD and a more malignant course of disease. Moreover, other factors such as air pollution, psychological factors, sleep disturbances and exercise influence the development and the course of IBD. Epigenetic mechanism like DNA methylation, histone modification and altered expression of miRNAS could explain the connection between genes and environmental factors in triggering the development of IBD.

Microbiome-Epigenome Interactions and the Environmental Origins of Inflammatory Bowel Diseases

The incidence of pediatric inflammatory bowel disease (IBD), which includes Crohn disease and ulcerative colitis, has risen alarmingly in the Western and developing world in recent decades. Epidemiologic (including monozygotic twin and migrant) studies highlight the substantial role of environment and nutrition in IBD etiology. Here we review the literature supporting the developmental and environmental origins hypothesis of IBD. We also provide a detailed exploration of how the human microbiome and epigenome (primarily through DNA methylation) may be important elements in the developmental origins of IBD in both children and adults.

Dietary Patterns and Risk of Inflammatory Bowel Disease in Europe: Results from the EPIC Study

BACKGROUND

Specific nutrients or foods have been inconsistently associated with ulcerative colitis (UC) or Crohn's disease (CD) risks. Thus, we investigated associations between diet as a whole, as dietary patterns, and UC and CD risks.

METHODS

Within the prospective EPIC (European Prospective Investigation into Cancer) study, we set up a nested matched case-control study among 366,351 participants with inflammatory bowel disease data, including 256 incident cases of UC and 117 of CD, and 4 matched controls per case. Dietary intake was recorded at baseline from validated food frequency questionnaires. Incidence rate ratios of developing UC and CD were calculated for quintiles of the Mediterranean diet score and a posteriori dietary patterns produced by factor analysis.

RESULTS

No dietary pattern was associated with either UC or CD risks. However, when excluding cases occurring within the first 2 years after dietary assessment, there was a positive association between a "high sugar and soft drinks" pattern and UC risk (incidence rate ratios for the fifth versus first quintile, 1.68 [1.00-2.82]; Ptrend = 0.02). When considering the foods most associated with the pattern, high consumers of sugar and soft drinks were at higher UC risk only if they had low vegetables intakes.

CONCLUSIONS

A diet imbalance with high consumption of sugar and soft drinks and low consumption of vegetables was associated with UC risk. Further studies are needed to investigate whether microbiota alterations or other mechanisms mediate this association.

Diet and nutritional factors in inflammatory bowel diseases

Inflammatory bowel disease (IBD) development is affected by complex interactions between environmental factors, changes in intestinal flora, various predisposing genetic properties and changes in the immune system. Dietary factors seem to play an underestimated role in the etiopathogenesis and course of the disease. However, research about food and IBD is conflicting. An excessive consumption of sugar, animal fat and linoleic acid is considered a risk factor for IBD development, whereas a high fiber diet and citrus fruit consumption may play a protective role. Also, appropriate nutrition in particular periods of the disease may facilitate achieving or prolonging remissions and most of all, improve the quality of life for patients. During disease exacerbation, a low fiber diet is recommended for most patients. In the remission time, an excessive consumption of alcohol and sulfur products may have a negative effect on the disease course. Attempts are also made at employing diets composed in detail in order to supplement IBD therapy. A diet with a modified carbohydrate composition, a semi-vegetarian diet and a diet low in fermentable oligosaccharides, disaccharides, monosaccharides and polyols are under investigation. Due to chronic inflammation as well as side effects of chronically used medications, patients with IBD are also at increased risk of nutritional factor deficiencies, including iron, calcium, vitamin D, vitamin B12, folic acid, zinc, magnesium and vitamin A. It should also be remembered that there is no single common diet suitable for all IBD patients; each of them is unique and dietary recommendations must be individually developed for each patient, depending on the course of the disease, past surgical procedures and type of pharmacotherapy.

The epidemiology and risk factors of inflammatory bowel disease

This review aimed to summarize the epidemiology (incidence, prevalence and morality) and risk factors of inflammatory bowel disease (IBD). IBD is a chronic, relapsing, inflammatory disorder of the gastrointestinal tract and includes Crohn's Disease (CD) and ulcerative colitis (UC). IBD has increasing incidence and prevalence in most of countries and becomes a global emerging disease. A westernized lifestyle or habits and some environmental factors have been found to contribute to the pathogenesis of IBD. The relevant risk factors include Smoking, hygiene hypothesis, microorganisms, appendectomy, medication, nutrition, and stress have all been found to be associated with the modality of IBD, but results are inconsistent on this issue in available studies. Therefore, more studies are required to identify and understand the environmental determinants of IBD.

Incidence Trends and Geographical Variability of Pediatric Inflammatory Bowel Disease in Slovenia: A Nationwide Study

Background. The aims of the study were to determine the incidence rate of pediatric inflammatory bowel disease (PIBD) and its trends for the period of 2002–2010 and to assess the geographical distribution of PIBD in Slovenia. Materials and Methods. Medical records of patients (0–18 years) with newly diagnosed IBD during the study period were retrospectively reviewed. Results. The mean incidence rate for IBD in 2002–2010 was 7.6 per 100,000 children and adolescents per year, 4.5 for Crohn's disease (CD), 2.9 for ulcerative colitis (UC), and 0.2 for IBD-unclassified, respectively. The incidence rate increased from 5.8 per 100,000 per year in 2002–2004 to 8.6 in 2005–2007 and remained stable afterwards. Statistically significant difference in the incidence rate between the Northeastern and Southwestern parts of the country was observed (p = 0.025). Conclusion. This nationwide study demonstrates that Slovenia is among the European countries with the highest PIBD incidence. During the study period a substantial rise of PIBD incidence was observed during the first half of the study and it seems to have stabilized in the second half. The significant difference in PIBD incidence between Northeastern and Southwestern parts of the country merits further exploration of the possible environmental factors.

DHA protects against experimental colitis in IL-10-deficient mice associated with the modulation of intestinal epithelial barrier function

A defect in the intestinal barrier is one of the characteristics of Crohn's disease (CD). The tight junction (TJ) changes and death of epithelial cells caused by intestinal inflammation play an important role in the development of CD. DHA, a long-chain PUFA, has been shown to be helpful in treating inflammatory bowel disease in experimental models by inhibiting the NF-κB pathway. The present study aimed at investigating the specific effect of DHA on the intestinal barrier function in IL-10-deficient mice. IL-10-deficient mice (IL-10(-/-)) at 16 weeks of age with established colitis were treated with DHA (i.g. 35.5 mg/kg per d) for 2 weeks. The severity of their colitis, levels of pro-inflammatory cytokines, epithelial gene expression, the distributions of TJ proteins (occludin and zona occludens (ZO)-1), and epithelial apoptosis in the proximal colon were measured at the end of the experiment. DHA treatment attenuated the established colitis and was associated with reduced infiltration of inflammatory cells in the colonic mucosa, lower mean histological scores and decreased levels of pro-inflammatory cytokines (IL-17, TNF-α and interferon-γ). Moreover, enhanced barrier function was observed in the DHA-treated mice that resulted from attenuated colonic permeability, rescued expression and corrected distributions of occludin and ZO-1. The results of the present study indicate that DHA therapy may ameliorate experimental colitis in IL-10(-/-) mice by improving the intestinal epithelial barrier function.

MicroRNA214 Is Associated With Progression of Ulcerative Colitis, and Inhibition Reduces Development of Colitis and Colitis-Associated Cancer in Mice

BACKGROUND & AIMS

Persistent activation of the inflammatory response contributes to the development of inflammatory bowel diseases, which increase the risk of colorectal cancer. We aimed to identify microRNAs that regulate inflammation during the development of ulcerative colitis (UC) and progression to colitis-associated colon cancer (CAC).

METHODS

We performed a quantitative polymerase chain reaction analysis to measure microRNAs in 401 colon specimens from patients with UC, Crohn's disease, irritable bowel syndrome, sporadic colorectal cancer, or CAC, as well as subjects without these disorders (controls); levels were correlated with clinical features and disease activity of patients. Colitis was induced in mice by administration of dextran sodium sulfate (DSS), and carcinogenesis was induced by addition of azoxymethane; some mice also were given an inhibitor of microRNA214 (miR214).

RESULTS

A high-throughput functional screen of the human microRNAome found that miR214 regulated the activity of nuclear factor-κB. Higher levels of miR214 were detected in colon tissues from patients with active UC or CAC than from patients with other disorders or controls and correlated with disease progression. Bioinformatic and genome-wide profile analyses showed that miR214 activates an inflammatory response and is amplified through a feedback loop circuit mediated by phosphatase and tensin homolog (PTEN) and PDZ and LIM domain 2 (PDLIM2). Interleukin-6 induced signal transducer and activator of transcription 3 (STAT3)-mediated transcription of miR214. A miR214 chemical inhibitor blocked this circuit and reduced the severity of DSS-induced colitis in mice, as well as the number and size of tumors that formed in mice given azoxymethane and DSS. In fresh colonic biopsy specimens from patients with active UC, the miR214 inhibitor reduced inflammation by increasing levels of PDLIM2 and PTEN.

CONCLUSIONS

Interleukin-6 up-regulates STAT3-mediated transcription of miR214 in colon tissues, which reduces levels of PDLIM2 and PTEN, increases phosphorylation of AKT, and activates nuclear factor-κB. The activity of this circuit correlates with disease activity in patients with UC and progression to colorectal cancer.

High School Diet and Risk of Crohn's Disease and Ulcerative Colitis

BACKGROUND

Diet may play an important role in the pathogenesis of Crohn's disease (CD) and ulcerative colitis (UC); yet, there are few prospective studies of dietary factors. None have examined the association between adolescent diet and risk of inflammatory bowel diseases (CD and UC).

METHODS

This study included women enrolled in Nurses' Health Study II who completed a validated high school dietary questionnaire in 1998. We examined the effect of dietary patterns (prudent or Western diet) and individual components of each patterns. We documented incident cases of CD and UC through 2011 based on physician review of medical records and used Cox proportional hazards models adjusting for confounders to estimate hazard ratios and confidence intervals for CD and UC.

RESULTS

Over 763,229 person-years of follow-up, we identified 70 incident cases of CD and 103 cases of UC. Compared with women in the lowest quartile of a prudent diet score (characterized by greater intake of fruits, vegetables, and fish), women in the highest quartile had a 53% lower risk of CD (hazard ratio, 0.47; 95% confidence interval, 0.23-0.98; P trend = 0.04). Specifically, greater intake of fish (P trend = 0.01) and fiber (P trend = 0.06) were associated with lower risk of CD. In contrast, Western diet score was not associated with risk of CD. Neither dietary patterns nor individual food or nutrient groups was associated with UC.

CONCLUSIONS

Adolescent diet is associated with risk of CD, but not UC, offering insights into disease pathogenesis.

Environmental risk factors in inflammatory bowel disease: a population-based case-control study in Asia-Pacific

OBJECTIVE

The rising incidence of inflammatory bowel disease in Asia supports the importance of environmental risk factors in disease aetiology. This prospective population-based case-control study in Asia-Pacific examined risk factors prior to patients developing IBD.

DESIGN

442 incident cases (186 Crohn's disease (CD); 256 UC; 374 Asians) diagnosed between 2011 and 2013 from eight countries in Asia and Australia and 940 controls (frequency-matched by sex, age and geographical location; 789 Asians) completed an environmental factor questionnaire at diagnosis. Unconditional logistic regression models were used to estimate adjusted ORs (aOR) and 95% CIs.

RESULTS

In multivariate model, being breast fed >12 months (aOR 0.10; 95% CI 0.04 to 0.30), antibiotic use (aOR 0.19; 0.07 to 0.52), having dogs (aOR 0.54; 0.35 to 0.83), daily tea consumption (aOR 0.62; 0.43 to 0.91) and daily physical activity (aOR 0.58; 0.35 to 0.96) decreased the odds for CD in Asians. In UC, being breast fed >12 months (aOR 0.16; 0.08 to 0.31), antibiotic use (aOR 0.48; 0.27 to 0.87), daily tea (aOR 0.63; 0.46 to 0.86) or coffee consumption (aOR 0.51; 0.36 to 0.72), presence of hot water tap (aOR 0.65; 0.46 to 0.91) and flush toilet in childhood (aOR 0.71; 0.51 to 0.98) were protective for UC development whereas ex-smoking (aOR 2.02; 1.22 to 3.35) increased the risk of UC.

CONCLUSIONS

This first population-based study of IBD risk factors in Asia-Pacific supports the importance of childhood immunological, hygiene and dietary factors in the development of IBD, suggesting that markers of altered intestinal microbiota may modulate risk of IBD later in life.

Oral Diets and Nutrition Support for Inflammatory Bowel Disease: What Is the Evidence?

Inflammatory bowel disease (IBD), which primarily includes Crohn's disease and ulcerative colitis, involves chronic inflammation of the gastrointestinal tract. The mechanisms of IBD pathogenesis are not well understood at this time, but likely involve an interaction between genetic, gut microbial, immune, and environmental factors. Emerging epidemiologic studies have suggested a relationship between specific dietary nutrients as an environmental factor and IBD risk. Clinical trials have also shown oral diets to have variable efficacy in affecting clinical outcomes for IBD. This review discusses the key studies that evaluated the use of various oral diets as well as nutrition support in the management of IBD.

What is known about the mechanisms of dietary influences in Crohn's disease?

Much has been written about the role of diet and risk for Crohn's disease (CD). However, the evidence is contradictory. Recent evidence has pointed to fiber playing an important role along with the possibility that dietary fat and overnutrition also have a role. Diet has a clearer place in disease modification, with some diets used in the treatment of CD. The lack of clarity stems from a poor understanding of the mechanisms underlying the relationship between diet and CD. Gut permeability is likely to play a key role in the risk for CD. Mechanisms whereby diet can affect gut permeability, including the effects of the gut microbiota, are reviewed. Modification of disease behavior is likely to be influenced by additional mechanisms, including recognition of complex food antigens. As with many other chronic diseases, a surrogate marker of CD risk would greatly aid evaluation of the dietary factors involved. Formal measures of gut permeability are too cumbersome for large-scale use, but fecal calprotectin may be a convenient measure of this. There are only preliminary data on the effect of diet and microbiota composition on fecal calprotectin and these require further investigation.

Pouring fuel on the fire: Th17 cells, the environment, and autoimmunity

Cytokines play a critical role in controlling the differentiation of CD4 Th cells into distinct subsets, including IL-17-producing Th17 cells. Unfortunately, the incidence of a number of autoimmune diseases, particularly those in which the IL-23/IL-17 axis has been implicated, has risen in the last several decades, suggesting that environmental factors can promote autoimmunity. Here we review the role of cytokines in Th17 differentiation, particularly the role of IL-23 in promoting the differentiation of a pathogenic subset of Th17 cells that potently induce autoimmune tissue inflammation. Moreover, we highlight emerging data that indicate that environmental factors, including the intestinal microbiota and changes in diet, can alter normal cytokine regulation with potent effects on Th17 differentiation and thus promote autoimmunity, which has strong implications for human disease.

Diet in the pathogenesis and treatment of inflammatory bowel diseases

Some of the most common symptoms of the inflammatory bowel diseases (IBD, which include ulcerative colitis and Crohn's disease) are abdominal pain, diarrhea, and weight loss. It is therefore not surprising that clinicians and patients have wondered whether dietary patterns influence the onset or course of IBD. The question of what to eat is among the most commonly asked by patients, and among the most difficult to answer for clinicians. There are substantial variations in dietary behaviors of patients and recommendations for them, although clinicians do not routinely endorse specific diets for patients with IBD. Dietary clinical trials have been limited by their inability to include a placebo control, contamination of study groups, and inclusion of patients receiving medical therapies. Additional challenges include accuracy of information on dietary intake, complex interactions between foods consumed, and differences in food metabolism among individuals. We review the roles of diet in the etiology and management of IBD based on plausible mechanisms and clinical evidence. Researchers have learned much about the effects of diet on the mucosal immune system, epithelial function, and the intestinal microbiome; these findings could have significant practical implications. Controlled studies of patients receiving enteral nutrition and observations made from patients on exclusion diets have shown that components of whole foods can have deleterious effects for patients with IBD. Additionally, studies in animal models suggested that certain nutrients can reduce intestinal inflammation. In the future, engineered diets that restrict deleterious components but supplement beneficial nutrients could be used to modify the luminal intestinal environment of patients with IBD; these might be used alone or in combination with immunosuppressive agents, or as salvage therapy for patients who do not respond or lose responsiveness to medical therapies. Stricter diets might be required to induce remission, and more sustainable exclusion diets could be used to maintain long-term remission.

Epidemiology and risk factors for IBD

IBD, comprising Crohn's disease and ulcerative colitis, is a chronic immunologically mediated disease at the intersection of complex interactions between genetics, environment and gut microbiota. Established high-prevalence populations of IBD in North America and Europe experienced the steepest increase in incidence towards the second half of the twentieth century. Furthermore, populations previously considered 'low risk' (such as in Japan and India) are witnessing an increase in incidence. Potentially relevant environmental influences span the spectrum of life from mode of childbirth and early-life exposures (including breastfeeding and antibiotic exposure in infancy) to exposures later on in adulthood (including smoking, major life stressors, diet and lifestyle). Data support an association between smoking and Crohn's disease whereas smoking cessation, but not current smoking, is associated with an increased risk of ulcerative colitis. Dietary fibre (particularly fruits and vegetables), saturated fats, depression and impaired sleep, and low vitamin D levels have all been associated with incident IBD. Interventional studies assessing the effects of modifying these risk factors on natural history and patient outcomes are an important unmet need. In this Review, the changing epidemiology of IBD, mechanisms behind various environmental associations and interventional studies to modify risk factors and disease course are discussed.

Tumour necrosis factor-α inhibition with lenalidomide alleviates tissue oxidative injury and apoptosis in ob/ob obese mice

Lenalidomide (Revlimid; Selleck Chemicals, Houston, TX, USA), an analogue of thalidomide, possesses potent cytokine modulatory capacity through inhibition of cytokines such as tumour necrosis factor (TNF)-α, a cytokine pivotal for the onset and development of complications in obesity and diabetes mellitus. The present study was designed to evaluate the effect of lenalidomide on oxidative stress, protein and DNA damage in multiple organs in an ob/ob murine model of obesity. To this end, C57BL/6 lean and ob/ob obese mice were administered lenalidomide (50 mg/kg per day, p.o.) for 5 days. Oxidative stress, protein and DNA damage were assessed using the conversion of reduced glutathione (GSH) to oxidized glutathione (GSSG), carbonyl formation and Comet assay, respectively. Apoptosis was evaluated using caspase 3 activity, and levels of Bax, Bcl-2, Bip, caspase 8, caspase 9 and TNF-α were assessed using western blot analysis. Lenalidomide treatment did not affect glucose clearance in lean or ob/ob mice. Obese mice exhibited a reduced GSH/GSSG ratio in the liver, gastrocnemius skeletal muscle and small intestine, as well as enhanced protein carbonyl formation, DNA damage and caspase 3 activity in the liver, kidney, skeletal muscle and intestine; these effects were alleviated by lenalidomide, with the exception of obesity-associated DNA damage in the liver and kidney. Western blot analysis revealed elevated TNF-α, Bax, Bcl-2, Bip, caspase 8 and caspase 9 in ob/ob mice with various degrees of reversal by lenalidomide treatment. Together, these data indicate that lenalidomide protects against obesity-induced tissue injury and protein damage, possibly in association with antagonism of cytokine production and cytokine-induced apoptosis and oxidative stress.

Dietary management of IBD--insights and advice

The current general interest in the use of food choice or diet in maintaining good health and in preventing and treating disease also applies to patients with IBD, who often follow poor or nutritionally challenging dietary plans. Unfortunately, dietary advice plays only a minor part in published guidelines for management of IBD, which sends a message that diet is not of great importance. However, a considerable evidence base supports a focused and serious attention to nutrition and diet in patients with IBD. In this Review, a step-wise approach in the evaluation and management of these patients is proposed. First, dietary intake and eating habits as well as current nutritional state should be documented, and corrective measures instituted. Secondly, dietary strategies as primary or adjunctive therapy for the reduction of inflammation and/or prevention of relapse of IBD should be seriously contemplated. Thirdly, use of diet to improve symptoms or lessen the effects of complications should be considered. Finally, dietary advice regarding disease prevention should be discussed when relevant. An increasing need exists for applying improved methodologies into establishing the value of current and new ways of using food choice as a therapeutic and preventive tool in IBD.

Environmental risk factors for inflammatory bowel diseases: a review

Inflammatory bowel diseases comprising Crohn's disease (CD) and ulcerative colitis (UC) are chronic immunologically mediated diseases. The key mechanism underlying the pathogenesis of these diseases is a dysregulated immune response to commensal flora in a genetically susceptible host. Thus intestinal microbial dysbiosis, host genetics, and the external environment all play an important role in the development of incident disease and in determining subsequent disease behavior and outcomes. There are several well-defined or putative environmental risk factors including cigarette smoking, appendectomy, diet, stress and depression, vitamin D as well as hormonal influence. The effect of some of the risk factors appears to differ between CD and UC suggesting that despite shared genetic and immunologic mechanisms, distinct pathways of pathogenesis exist. There is a growing body of literature identifying risk factors for incident disease. There is less rigorous literature defining triggers of relapse, and few controlled clinical trials examining if modification of such risk factors results in an improvement in patient outcomes. This is an area of considerable patient, physician, and scientific interest, and there is an important unmet need for rigorous studies of the external environment in disease pathogenesis and subsequent course.

Measures of obesity and risk of Crohn's disease and ulcerative colitis

BACKGROUND

Obesity is associated with intestinal-specific inflammation. Nonetheless, a specific role of obesity in the etiology of inflammatory bowel disease is unclear.

METHODS

We conducted a prospective cohort study of U.S. women enrolled in 1989 in the Nurses' Health Study II. At baseline, we collected information on height, weight, waist and hip circumference, weight at age 18, and body shape at age 20. We used Cox proportional hazard models to calculate hazard ratios and 95% confidence intervals (CIs).

RESULTS

Among 111,498 women (median age, 35 yr), we documented 153 cases of Crohn's disease (CD) and 229 cases of ulcerative colitis (UC) more than 18 years of follow-up, encompassing 2,028,769 person-years. Compared with women with normal BMI, the multivariate-adjusted hazard ratios of CD were 2.33 (95% CI, 1.15-4.69) for obese women at age 18 and 1.58 (95% CI, 1.01-2.47) for obese women at baseline. Increasing weight gain between age 18 and baseline was associated with increased risk of CD (Ptrend = 0.04). Adolescent body habitus was also associated with risk of CD with a multivariate-adjusted hazard ratio of CD of 1.63 (95% CI, 1.07-2.50) for women with overweight/obese body shape compared with women with a thin/slender body shape. We did not observe a significant association between any of these anthropometric measures and risk of UC.

CONCLUSIONS

In a large prospective cohort of U.S. women, measures of adiposity were associated with an increased risk of CD but not UC. Additional studies are needed to elucidate the biological mechanisms by which excess adiposity may increase the risk of CD.

Fish consumption and risk of non-gallstone-related acute pancreatitis: a prospective cohort study

BACKGROUND

Epidemiologic data on the role of diet in acute pancreatitis are sparse.

OBJECTIVE

We examined the association of total fish consumption, as well as of consumption of fatty fish and lean fish separately, with risk of non-gallstone-related acute pancreatitis.

DESIGN

We used data from 2 prospective cohorts, the Cohort of Swedish Men and the Swedish Mammography Cohort, that included 39,267 men and 32,191 women who were aged 45-84 y at the start of a 13-y follow-up period (1998-2010). Fish consumption was assessed by using a food-frequency questionnaire at baseline, and cases of incident non-gallstone-related acute pancreatitis were identified by linkage to the Swedish National Patient Register. HRs were estimated by using Cox proportional hazard models.

RESULTS

During a total follow-up of 860,176 person-years, 320 cases (209 cases in men and 111 cases in women) of incident non-gallstone-related acute pancreatitis were identified. We observed that total fish consumption ≤2.0-3.0 servings/wk was associated with a significantly decreased risk of the disease (P-nonlinearity = 0.017). In comparison with 0.9 servings/wk, multivariable-adjusted HRs were 0.86 (95% CI: 0.76, 0.96), 0.77 (95% CI: 0.62, 0.96), and 0.85 (95% CI: 0.65, 1.10) for 1.4, 2.4, and 3.5 servings/wk, respectively. In the analysis of fatty fish and lean fish, we observed that the consumption of each subtype had a similarly shaped association with risk of non-gallstone-related acute pancreatitis as that observed for total fish consumption, although neither was significant. Multivariable-adjusted HRs were 0.83 for fatty fish (95% CI: 0.65, 1.04) and 0.87 for lean fish (95% CI: 0.69, 1.11) when 0.6-2.0 servings/wk was compared with ≤0.5 servings/wk.

CONCLUSION

Our data suggest that the consumption of total fish (fatty fish and lean fish combined) may be associated with decreased risk of non-gallstone-related acute pancreatitis.

Effects of RAMEA-complexed polyunsaturated fatty acids on the response of human dendritic cells to inflammatory signals

The n-3 fatty acids are not produced by mammals, although they are essential for hormone synthesis and maintenance of cell membrane structure and integrity. They have recently been shown to inhibit inflammatory reactions and also emerged as potential treatment options for inflammatory diseases, such as rheumatoid arthritis, asthma and inflammatory bowel diseases. Dendritic cells (DC) play a central role in the regulation of both innate and adaptive immunity and upon inflammatory signals they produce various soluble factors among them cytokines and chemokines that act as inflammatory or regulatory mediators. In this study we monitored the effects of α-linoleic acid, eicosapentaenoic acid and docosahexaenoic acid solubilized in a dimethyl sulfoxide (DMSO)/ethanol 1:1 mixture or as complexed by randomly methylated α-cyclodextrin (RAMEA) on the inflammatory response of human monocyte-derived dendritic cells (moDC). The use of RAMEA for enhancing aqueous solubility of n-3 fatty acids has the unambiguous advantage over applying RAMEB (the β-cyclodextrin analog), since there is no interaction with cell membrane cholesterol. In vitro differentiated moDC were left untreated or were stimulated by bacterial lipopolysaccharide and polyinosinic:polycytidylic acid, mimicking bacterial and viral infections, respectively. The response of unstimulated and activated moDC to n-3 fatty acid treatment was tested by measuring the cell surface expression of CD1a used as a phenotypic and CD83 as an activation marker of inflammatory moDC differentiation and activation by using flow cytometry. Monocyte-derived DC activation was also monitored by the secretion level of the pro- and anti-inflammatory cytokines IL-1β, TNF-α, IL-6, IL-10 and IL-12, respectively. We found that RAMEA-complexed n-3 fatty acids reduced the expression of CD1a protein in both LPS and Poly(I:C) stimulated moDC significantly, but most efficiently by eicosapentaenic acid, while no significant change in the expression of CD83 protein was observed. The production of IL-6 by LPS-activated moDC was also reduced significantly when eicosapentaenic acid was added as a RAMEA complex as compared to its DMSO-solubilized form or to the other two n-3 fatty acids either complexed or not. Based on these results n-3 fatty acids solubilized by RAMEA provide with a new tool for optimizing the anti-inflammatory effects of n-3 fatty acids exerted on human moDC and mediated through the GP120 receptor without interfering with the cell membrane structure.

Sleep duration affects risk for ulcerative colitis: a prospective cohort study

BACKGROUND & AIMS

Sleep deprivation is associated with production of inflammatory cytokines. Disturbed sleep quality has been associated with increased risk of disease flare in patients with Crohn's disease (CD) or ulcerative colitis (UC). However, the association between sleep and risk of incident CD and UC has not been previously examined.

METHODS

We conducted a prospective study of women who were enrolled in the Nurses' Health Study (NHS) I since 1976 and NHS II since 1989 and followed through detailed biennial questionnaires with >90% follow-up. We examined the association of sleep duration reported in 1986 in NHS I and 2001 in NHS II with incident CD and UC, diagnosed through 2010, in NHS I and 2009 in NHS II. Cox proportional hazards models adjusting for potential confounders were used to calculate hazard ratios and 95% confidence intervals (CIs).

RESULTS

Among 151,871 women, we confirmed 191 cases of CD (incidence, 8/100,000 person-years) and 230 cases of UC (incidence, 10/100,000 person-years) over 2,292,849 person-years. Compared with women with reported usual sleep durations of 7-8 h/day (incidence, 8/100,000 person-years), women with reported sleep duration <6 h/day (11/100,000 person-years) or >9 h/day (20/100,000 person-years) had a higher incidence of UC (P < .05). The multivariate hazard ratios for UC were 1.51 (95% CI, 1.10-2.09) for sleep durations <6 h/day and 2.05 (95% CI, 1.44-2.92) for sleep durations >9 h/day, compared with sleep durations of 7-8 h/day. In contrast, sleep duration did not modify risk of CD. Duration of rotating night shift work was not associated with CD or UC.

CONCLUSIONS

On the basis of data from the NHS I and II, less than 6 hours sleep/day and more than 9 hours sleep/day are each associated with an increased risk of UC. Further studies are needed to evaluate sleep as a modifiable risk factor in the pathogenesis and progression of IBD.

Hospitalization for Inflammatory Bowel Disease is Associated with Increased Risk of Breast Cancer: A Nationwide Cohort Study of an Asian Population

PURPOSE

To learn whether women with inflammatory bowel disease (IBD) exhibit a higher risk of breast cancer.

METHODS

We identified 4,856 women with IBD symptoms from 1998 to 2008 and 19,424 control patients without the disorder, frequency matched by age, sex, and admission year. Both cohorts were followed-up until the end of 2010 to estimate the risk of breast cancer.

RESULTS

Overall, the incidence of breast cancer was similar in the IBD and control cohorts (1.31 vs. 1.25 per 1,000 person-years). The adjusted hazard ratio of breast cancer was 0.95 (95 % confidence interval 0.66-1.36) for the IBD patients. Further analysis revealed that neither Crohn disease nor ulcerative colitis was associated with the risk of developing breast cancer in women. The age-specific analysis indicated that the incidence of breast cancer was highest in the 45- to 65-year-old age group in both cohorts. The incidence of breast cancer was significantly increased in patients who required hospitalization twice or more per year, compared with the control cohort (adjusted hazard ratio 8.45; 95 % confidence interval 4.64-15.4). Moreover, age-specific analysis showed that patients aged less than 65 years old (≤44 or 45-65 years of age) exhibited a strong association between IBD hospitalization and breast cancer risk.

CONCLUSIONS

The risk of breast cancer was positively proportional to the frequency of admission for IBD. Therefore, careful surveillance of breast cancer should be sought for female IBD patients with 2 or more annual hospitalizations.

Diet and inflammatory bowel disease: review of patient-targeted recommendations

Patients have strong beliefs about the role of diet in the cause of inflammatory bowel disease (IBD) and in exacerbating or alleviating ongoing symptoms from IBD. The rapid increase in the incidence and prevalence of IBD in recent decades strongly suggests an environmental trigger for IBD, one of which may be dietary patterns. There are several pathways where diet may influence intestinal inflammation, such as direct dietary antigens, altering the gut microbiome, and affecting gastrointestinal permeability. However, data that altering diet can change the natural history of IBD are scarce, and evidence-based dietary guidelines for patients with IBD are lacking. Patients, therefore, seek nonmedical resources for dietary guidance, such as patient support groups and unverified sources on the Internet. The aim of this review is to identify patient-targeted dietary recommendations for IBD and to critically appraise the nutritional value of these recommendations. We review patient-targeted dietary information for IBD from structured Internet searches and popular defined diets. Patient-targeted dietary recommendations focus on food restrictions and are highly conflicting. High-quality dietary intervention studies are needed to facilitate creation of evidence-based dietary guidelines for patients with IBD.