Maintenance of remission in inflammatory bowel disease using omega-3 fatty acids (fish oil): a systematic review and meta-analyses

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

INTRODUCTION

Dietary fats influence intestinal inflammation and regulate mucosal immunity. Data on the association between dietary fat and risk of Crohn's disease (CD) and ulcerative colitis (UC) are limited and conflicting.

METHODS

We conducted a prospective study of women enrolled in the Nurses' Health Study cohorts. Diet was prospectively ascertained every 4 years using a validated semi-quantitative food frequency questionnaire. Self-reported CD and UC were confirmed through medical record review. We examined the effect of energy-adjusted cumulative average total fat intake and specific types of fat and fatty acids on the risk of CD and UC using Cox proportional hazards models adjusting for potential confounders.

RESULTS

Among 170,805 women, we confirmed 269 incident cases of CD (incidence 8/100,000 person-years) and 338 incident cases of UC (incidence 10/100,000 person-years) over 26 years and 3,317,338 person-years of follow-up. Cumulative energy-adjusted intake of total fat, saturated fats, unsaturated fats, n-6 and n-3 polyunsaturated fatty acids (PUFAs) were not associated with risk of CD or UC. However, greater intake of long-chain n-3 PUFAs was associated with a trend towards lower risk of UC (HR 0.72, 95% CI 0.51 to 1.01). In contrast, high long-term intake of trans-unsaturated fatty acids was associated with a trend towards an increased incidence of UC (HR 1.34, 95% CI 0.94 to 1.92).

CONCLUSIONS

A high intake of dietary long-chain n-3 PUFAs may be associated with a reduced risk of UC. In contrast, high intake of trans-unsaturated fats may be associated with an increased risk of UC.

Popular exclusionary diets for inflammatory bowel disease: the search for a dietary culprit

The evolving understanding of the role of the microbiome and environmental factors in the pathogenesis of inflammatory bowel disease makes diet an interesting and potentially powerful tool in the treatment of disease. However, at this time, evidence is limited but anecdotal reports of success abound. There is a bewildering array of new diets being tried by patients in an attempt to control diseases. This review attempts to summarize the most common diets for the treating physician.

Nutrition optimization prior to surgery

Optimization of metabolic state prior to major surgery leads to improved surgical outcomes. Nutrition screening protocols should be implemented in the preoperative evaluation, possibly as part of a bundle. Strategies to minimize hyperglycemia and insulin resistance by aggressive preoperative nutrition and carbohydrate loading may promote maintenance of a perioperative anabolic state, improving healing, reducing complications, and shortening the time to recovery of bowel function and hospital discharge. Short courses of preoperative immune-modulating formulas, using combinations of arginine, ω-3 fatty acids, and other nutrients, have been associated with improved surgical outcomes. These immune-modulating nutrients are key elements of metabolic pathways that promote attenuation of the metabolic response to stress and improve both wound healing and immune function. Patients with severe malnutrition and gastrointestinal dysfunction may benefit from preoperative parenteral nutrition. Continuation of feeding through the intraoperative period for severely stressed hypermetabolic patients undergoing nongastrointestinal surgery is another strategy to optimize metabolic state and reduce prolonged nutrition deficits. In this paper, we review the importance of preoperative nutrition and strategies for effective preoperative nutrition optimization.

Review article: evidence-based dietary advice for patients with inflammatory bowel disease

BACKGROUND

The therapeutic effect of enteral nutrition in Crohn's disease (CD) and the epidemiological associations between diet and inflammatory bowel disease (IBD) implicate diet in IBD causation. There is little evidence, however, to support specific dietary changes and patients often receive contradictory advice.

AIM

To review the literature on the impacts of diet on IBD causation and activity to produce guidance based on 'best available evidence'.

METHOD

Review of Medline, Embase and Cochrane databases from 1975 to 2012 using MeSH headings 'crohn's disease' 'ulcerative colitis' 'enteral' 'diet' 'nutrition' 'fatty acid' and 'food additives'.

RESULTS

Enteral nutrition with a formula-defined feed is effective treatment for CD, but approximately 50% of patients relapse within 6 months of return to normal diet. There is no direct evidence of benefit from any other specific dietary modification in CD, but indirect evidence supports recommendation of a low intake of animal fat, insoluble fibre and processed fatty foods containing emulsifiers. Foods tolerated in sustained remission may not be tolerated following relapse. Some evidence supports vitamin D supplementation. In ulcerative colitis (UC), evidence is weaker, but high intakes of meat and margarine correlate with increased UC incidence and high meat intake also correlates with increased likelihood of relapse.

CONCLUSIONS

There is little evidence from interventional studies to support specific dietary recommendations. Nevertheless, people with IBD deserve advice based on 'best available evidence' rather than no advice at all, although dietary intake should not be inappropriately restrictive. Further interventional studies of dietary manipulation are urgently required.

Systematic review: the efficacy of herbal therapy in inflammatory bowel disease

BACKGROUND

Complementary and alternative medicine (CAM), particularly herbal therapy, is widely used by patients with inflammatory bowel disease (IBD) but controlled data are limited.

AIM

To systematically review the literature on the efficacy of herbal therapy in the treatment of ulcerative colitis (UC) and Crohn's disease (CD).

METHODS

Publications in English and non-English literatures (MEDLINE, EMBASE, EBM Reviews, AMED, Global Health) were searched from 1947 to 2013 for controlled clinical studies of herbal therapy in IBD. Outcome measures included response and remission rates.

RESULTS

Twenty-one randomised controlled trials (14 UC; 7 CD) including a total of 1484 subjects (mean age 41, 50% female) were analysed. In UC, aloe vera gel, Triticum aestivum (wheat grass juice), Andrographis paniculata extract (HMPL-004) and topical Xilei-san were superior to placebo in inducing remission or response, and curcumin was superior to placebo in maintaining remission; Boswellia serrata gum resin and Plantago ovata seeds were as effective as mesalazine, whereas Oenothera biennis (evening primrose oil) had similar relapse rates as omega-3 fatty acids in the treatment of UC. In CD, Artemisia absinthium (wormwood) and Tripterygium wilfordii were superior to placebo in inducing remission, and preventing clinical recurrence of post-operative CD respectively.

CONCLUSIONS

Randomised controlled trials of herbal therapy for the treatment of IBD show encouraging results but studies remain limited and heterogenous. Larger controlled studies with stricter endpoints and better-defined patient groups are required to obtain more conclusive results on the use of CAM therapies in IBD.

Prevention of colitis-associated cancer: natural compounds that target the IL-6 soluble receptor

The risk of developing colorectal cancer increases in patients with inflammatory bowel disease (IBD) and a growing body of evidence shows the critical role of interleukin (IL-6) in this process. IL-6 is both a pro- and anti-inflammatory cytokine whose effects are mediated through activation of STAT3. Recent studies have also demonstrated that IL-6 trans-signaling through its soluble receptor occurs in IBD and cancer. IL-6 trans-signaling therefore is emerging as an attractive approach to diminish the inflammatory signals in conditions of chronic inflammation. The purpose of cancer chemoprevention is to either delay the onset or progression from precancerous lesions. Natural compounds because of their low toxicity render themselves excellent candidates that can be administered over the lifetime of an individual. With the focus of managing IBD over a long time and preventing onset of colitis-associated cancer, we believe that there should be increased research focus on identifying chemopreventive compounds that can render themselves to long term use possibly for the lifetime of predisposed individuals. Here, we review the role of IL-6 signaling in IBD and colitis-associated cancer and underscore the importance of searching for natural compounds that would target the IL-6 trans-signaling pathway as a way to diminish chronic inflammatory conditions in the gastrointestinal tract and possibly hamper the progression to colon cancer. We propose that effective screening and identification of natural chemopreventive compounds that target IL-6 trans-signaling has important implications for the development of optimal strategies against cancer development triggered by inflammation.

Dietary oils modify the host immune response and colonic tissue damage following Citrobacter rodentium infection in mice

Inflammatory bowel disease is an intestinal inflammatory disorder of multifactorial origin, in which diets that favor high n-6 and low n-3 fatty acids have been implicated. The present study addressed whether dietary n-6 and n-3 fatty acids alter colonic mucosal response to Citrobacter rodentium (C. rodentium) infection. Mice were fed diets identical except for fatty acids, with an energy percentage of 15% 18:2n-6 and <0.06% 18:3n-3, 4.2% 18:2n-6 and 1.9% 18:3n-3, or 1.44% 20:5n-3, 4.9% 22:6n-3, 0.32% 18:2n-6, and 0.12% 18:3n-3 from safflower, canola, or fish oil, respectively for 3 wk before infection. Dietary oils had no effect on colonic C. rodentium growth but altered colon 20:4n-6/(20:5n-3+22:6n-3) with 9.40 ± 0.06, 1.94 ± 0.08, and 0.32 ± 0.03% in colon phosphatidylcholine and 3.82 ± 0.18, 1.14 ± 0.02, and 0.30 ± 0.02% in phosphatidylethanolamine of mice fed safflower, canola, or fish oil, respectively. At 10 days postinfection, histological damage, F4/80-positive macrophages, and myeloperoxidase-positive neutrophils in colonic mucosa were higher in infected mice fed safflower than fish oil. Colon gene transcripts for macrophage inflammatory protein 2, keratinocyte cytokine, and monocyte chemoattractant protein 1 expression were significantly higher in infected mice fed safflower than canola or fish oil; IFN-γ, IL-6, and IL-17A expression were significantly elevated in mice fed safflower rather than fish oil; and IL-10 was significantly higher in mice fed fish oil rather than canola or safflower oil. This study demonstrates that oils high in 18:2n-6 with minimal n-3 fatty acids exacerbate mucosal immune response, whereas oils high in n-3 fatty acids attenuate mucosal immune response to C. rodentium. These studies implicate dietary oils as environmental modifiers of intestinal inflammation in response to infection.

Fish consumption by children in Canada: Review of evidence, challenges and future goals

Fish consumption is of great importance to children's health and is essential for neurodevelopment, which begins in pregnancy and continues throughout early childhood and into adolescence. However, fish consumption presents conflicting health outcomes associated with its nutritional benefits and its adverse contaminant risks, because both avoiding fish as well as the consumption of contaminated fish can potentially harm children. This may be challenging to communicate. The present review was performed to assess the current knowledge and recommendations around 'smart' fish-consumption decisions. Health Canada advises, as well as other advisories and guides, that fish should be consumed for its health benefits, while also informing consumers, especially women and children, to limit certain fish consumption. The current literature must attempt to handle the challenges inherent in communicating the dilemmas of children's fish consumption. Incorporation of new knowledge translation strategies are proposed as a means to raise the level of knowledge about optimal fish consumption practices.

Ulcerative colitis: prevention of relapse

The clinical management of ulcerative colitis (UC) involves first treating the acute symptoms to induce remission, and then successfully maintaining it. Oral 5-aminosalicylic acids are safe and useful for maintaining remission in patients with UC. In terms of adherence, a once-daily form of 5-aminosalicylic acid is superior in maintaining remission as compared with split dosing. Patients at high risk of relapse may be candidates for treatment with thiopurines and/or biologics in the early stages of UC. Calcineurin inhibitors, such as cyclosporine and tacrolimus, are effective for severe, steroid-refractory UC patients. It is suggested that these patients use thiopurines as their maintenance therapy once they achieve remission with calcineurin inhibitors. Recent studies have confirmed that biologics are effective for inducing clinical and endoscopic remission of UC, and thus they may improve long-term prognosis of UC.

Nutrition and diet in inflammatory bowel disease

PURPOSE OF REVIEW

Diet is known to have a major role in the expression of inflammatory bowel disease (IBD). The role of dietary interventions and enteral nutrition in the management of IBD remains unelucidated. This study was to review the current evidence for dietary risk factors for the development of IBD and the efficacies of dietary and enteral interventions.

RECENT FINDINGS

High dietary intakes of total fats, polyunsaturated fatty acids, omega-6 fatty acids, and meat are associated with an increased risk of Crohn's disease and ulcerative colitis. Further prospective studies are required to confirm these observations. Among various dietary interventions, none has shown striking efficacy. Meta-analyses have shown enteral nutrition to be inferior to corticosteroids in adults with active Crohn's disease. However, in children, a meta-analysis has shown no significant difference in the remission rates between enteral nutrition and corticosteroid therapy. Although the evidence level is not striking, enteral nutrition may be useful for maintaining remission in patients with quiescent Crohn's disease.

SUMMARY

Dietary risk factors for IBD and the therapeutic benefit of dietary and enteral interventions need to be confirmed by further well designed studies in large cohorts of patients.

Polyunsaturated fatty acids in inflammatory bowel diseases: a reappraisal of effects and therapeutic approaches

Recent epidemiological studies highlight the key role of the type of consumed unsaturated fatty acid and the development of ulcerative colitis (UC). We aimed to review the potential mechanisms behind the antiinflammatory effects of unsaturated fatty acids on intestinal inflammation, to discuss their potential limitations, and to propose a new reappraisal of polyunsaturated fatty acids (PUFAs) in the pathophysiology of inflammatory bowel disease (IBD). A literature search using PubMed was carried out to identify relevant studies (basic science, epidemiological studies, or clinical trials) with unsaturated fatty acids and IBD. Only articles published in English were included. IBD patients exhibit an altered lipid metabolism. While in vitro and in vivo studies have demonstrated the antiinflammatory properties of n-3 polyunsaturated fatty acids in experimental models IBD, results of clinical trials have been disappointing. In addition, the impact of fatty acid on innate immunity as an alternative therapeutic approach is explored. This may offer insight into therapeutic avenues for designing n-3 PUFA diet therapy for IBD.

Nutritional modulators of ulcerative colitis: Clinical efficacies and mechanistic view

Ulcerative colitis (UC) is an inflammation-associated disease of the colon and rectum. The onset and progress of the disease are directly influenced by the nature of the intestinal microflora, the intestinal barrier function, and the immunological responses of the host. The epithelial invasion of pathogenic bacteria due to excess contact and/or barrier dysfunction is related to inflammation mediated by intestinal immune responses. Although the etiology of UC is not clearly understood, recent studies have shown a rising incidence of UC worldwide, and this phenomenon is more prominent in Asian countries and in Asian immigrants in Western countries. The increased prevalence of UC also contributes to an increased risk of developing colorectal cancer. Environmental factors, including changes in dietary habits, have been suggested as major risk factors of UC. A systematic review showed a negative association between UC risk and vegetable intake, whereas total fat, omega-6 fatty acids and meat intake were positively associated with an increased risk of UC. Individual dietary factors and energy balance have been suggested as having important roles in inducing changes in the microbial population and intestinal barrier integrity and in regulating inflammatory immune responses, directly or indirectly. Excess energy intake is now known to increase pathogenic microbial populations. Likewise, the application of appropriate probiotics may reverse the pathogenic progression of the disease. In the meantime, dietary anti-inflammatory compounds, including omega-3 fatty acids and other phytochemicals, may directly suppress inflammatory responses in the course of UC development. In this review, the increased prevalence of UC and its management are interpreted from the standpoint of nutritional modulation to regulate the intestinal microflora population, intestinal epithelium permeability, and inflammatory responses.

Inhibitory effects of omega-3 fatty acids on injury-induced epidermal growth factor receptor transactivation contribute to delayed wound healing

Epidermal growth factor receptor (EGFR)-mediated signaling is required for optimal intestinal wound healing. Since n-3 polyunsaturated fatty acids (PUFA), specifically docosahexaenoic acid (DHA), alter EGFR signaling and suppress downstream activation of key signaling pathways, we hypothesized that DHA would be detrimental to the process of intestinal wound healing. Using a mouse immortalized colonocyte model, DHA uniquely reduced EGFR ligand-induced receptor activation, whereas DHA and its metabolic precursor eicosapentaenoic acid (EPA) reduced wound-induced EGFR transactivation compared with control (no fatty acid or linoleic acid). Under wounding conditions, the suppression of EGFR activation was associated with a reduction in downstream activation of cytoskeletal remodeling proteins (PLCγ1, Rac1, and Cdc42). Subsequently, DHA and EPA reduced cell migration in response to wounding. Mice were fed a corn oil-, DHA-, or EPA-enriched diet prior to intestinal wounding (2.5% dextran sodium sulfate for 5 days followed by termination after 0, 3, or 6 days of recovery). Mortality was increased in EPA-fed mice and colonic histological injury scores were increased in EPA- and DHA-fed mice compared with corn oil-fed (control) mice. Although kinetics of colonic EGFR activation and downstream signaling (PLCγ1, Rac1, and Cdc42) were delayed by both n-3 PUFA, colonic repair was increased in EPA- relative to DHA-fed mice. These results indicate that, during the early response to intestinal wounding, DHA and EPA uniquely delay the activation of key wound-healing processes in the colon. This effect is mediated, at least in part, via suppression of EGFR-mediated signaling and downstream cytoskeletal remodeling.

Gene alterations and intestinal mucosal changes following growth factor and omega-3 exposure in a rat model of inflammatory bowel disease

BACKGROUND

We have previously shown that there is synergism between Hepatocyte Growth Factor (HGF) and Omega-3 (OM-3) enriched feeds using an immunologic model of inflammatory bowel disease (IBD). This combination decreased inflammation and cytokine levels and increased microvascular density and mucosal mass. This study evaluates the gene alterations that occurred using this same model.

METHODS

Twenty adult female transgenic HLA-B27 rats were divided into four groups: Group 1: (Regular feeds, IV saline); Group 2: (OM-3 feeds, IV saline); Group 3: (Regular feeds, IV HGF 150 μg/kg/day); Group 4: (OM-3 feeds, IV HGF 150 μg/kg/day). Rats were sacrificed 14 days after pump placement. Bowel was harvested and RNA extracted. Microarray gene chips were used. Statistical analysis was done by analysis of variance using Partek Genomics Suite. Results were significant if fold change was more than 2 or less than -2, with P<0.05.

RESULTS

In the ileum, HGF up- or down-regulated 34 genes, while OM-3 affected 60 genes. Together 68 genes were affected. Families with a synergistic effect included Solute Carrier Proteins, ATP Binding Cassette Proteins, and Matrix Metalloproteinases. In the colon, 23 genes were affected by HGF, while 66 genes were affected with OM-3. Combined exposure affected 32 genes, including a synergistic effect on solute carrier proteins, aquaporins, and immunologic factors.

CONCLUSIONS

There is a synergistic gene alteration effect of exposure of two (HGF and Omega-3 enriched feeds) agents on bowel mucosa. Of most interest was the synergistic effect on the solute carrier protein family, a previously identified gene family up-regulated in response to intestinal failure.

Design of foods with bioactive lipids for improved health

Numerous studies have found an association between the consumption of certain bioactive lipids and improved human health, e.g., the prevention, delay, or treatment of chronic and acute diseases, such as cancer, cardiovascular disease (CVD), osteoporosis, and immune disorders. In this review, we discuss food-based sources and potential beneficial attributes of major dietary bioactive lipids: polyunsaturated fatty acids; carotenoids; phytosterols and phytostanols; and fat-soluble vitamins. We summarize the various challenges associated with incorporating these bioactive lipids into foods and beverages, such as poor water solubility, high melting point, and low chemical stability. Finally, we propose several techniques that have been used to solve the challenges and integrate dietary bioactive lipids into foods for improved health.

Dietary n-3 polyunsaturated fatty acids (PUFA) decrease obesity-associated Th17 cell-mediated inflammation during colitis

Clinical and experimental evidence suggests that obesity-associated inflammation increases disease activity during colitis, attributed in part to the effects of Th17 cells. Using a model of concurrent obesity and colitis, we monitored changes in critical immune cell subsets and inflammatory biomarker expression in three key tissues: visceral adipose tissue, colon (local inflammatory site) and spleen (systemic inflammatory site), and we hypothesized that n-3 PUFA would reduce the percentage of inflammatory immune cell subsets and suppress inflammatory gene expression, thereby improving the disease phenotype. Obesity was induced in C57BL/6 mice by feeding a high fat (HF) diet (59.2% kcal) alone or an isocaloric HF diet supplemented with fish oil (HF-FO) for 12 weeks. Colitis was induced via a 2.5% trinitrobenzene sulfonic acid (TNBS) enema. The HF-FO diet improved the obese phenotype by reducing i) serum hormone concentrations (leptin and resistin), ii) adipose tissue mRNA expression of inflammatory cytokines (MCP-1, IFNγ, IL-6, IL17F and IL-21) and iii) total (F4/80⁺ CD11b⁺) and inflammatory adipose tissue M1 (F4/80⁺ CD11c⁺) macrophage content compared to HF (P<0.05). In addition, the HF-FO diet reduced both colitis-associated disease severity and colonic mRNA expression of the Th17 cell master transcription factor (RORγτ) and critical cytokines (IL-6, IL-17A, IL-17F, IL-21, IL-23 and IFNγ) versus HF (P<0.05). Compared to HF, the percentage of both splenic Th17 and Th1 cells were reduced by the HF-FO group (P<0.05). Under ex vivo polarizing conditions, the percentage of HF-FO derived CD4⁺ T cells that reached Th17 cell effector status was suppressed (P = 0.05). Collectively, these results indicate that n-3 PUFA suppress Th1/Th17 cells and inflammatory macrophage subsets and reconfigure the inflammatory gene expression profile in diverse tissue sites in obese mice following the induction of colitis.

Impact of environmental and dietary factors on the course of inflammatory bowel disease

Besides their possible effects on the development of inflammatory bowel disease (IBD), some environmental factors can modulate the clinical course of both ulcerative colitis (UC) and Crohn’s disease (CD). This review is mainly devoted to describing the current knowledge of the impact of some of these factors on the outcome of IBD, with special emphasis on smoking and diet. Although the impact of smoking on the susceptibility to develop CD and UC is firmly established, its influence on the clinical course of both diseases is still debatable. In CD, active smoking is a risk factor for postoperative recurrence. Beyond this clinical setting, smoking cessation seems to be advantageous in those CD patients who were smokers at disease diagnosis, while smoking resumption may be of benefit in ex-smokers with resistant UC. The role of dietary habits on the development of IBD is far from being well established. Also, food intolerances are very frequent, but usually inconsistent among IBD patients, and therefore no general dietary recommendations can be made in these patients. In general, IBD patients should eat a diet as varied as possible. Regarding the possible therapeutic role of some dietary components in IBD, lessons should be drawn from the investigation of the primary therapeutic effect of enteral nutrition in CD. Low-fat diets seem to be particularly useful. Also, some lipid sources, such as olive oil, medium-chain triglycerides, and perhaps omega-3 fatty acids, might have a therapeutic effect. Fermentable fiber may have a role in preventing relapses in inactive UC.

Novel methodologies for assessing omega-3 fatty acid status - a systematic review

Over the last few decades n-3 long chain polyunsaturated fatty acid status became of special interest for scientists. Biochemical measures on the n-3 fatty acid status vary depending on body compartment assessed and measures chosen. Plasma phospholipids and red blood cell membrane phospholipids are mainly used as n-3 fatty acid status marker. The conventional analysis of phospholipid fatty acids involves lipid extraction and consecutive chromatographic separation of phospholipids from other lipid fractions, which is time-consuming and costly. In recent years, different investigators have tried to overcome these limitations by using other biological markers or by modifying the analytical procedures used to assess n-3 fatty acid status. The aim of this systematic review was to provide an overview on these novel analytical methods developed for the fatty acid quantification by gas chromatography, highlights the methodological limitations, and discusses advantages or disadvantages of the biological markers used. Seventeen papers were identified that fulfilled the inclusion criteria. New opportunities arise from sensitive and precise high-throughput methodologies for assessment of plasma total lipid and plasma glycerophospholipid fatty acids, as well as cheek cell fatty acid composition.

Postoperative recurrent luminal Crohn's disease: a systematic review

Despite improved immunosuppressive therapy, surgical resection is still often required for uncontrolled inflammatory disease and the stenosing and perforating complications of Crohn's disease. However, surgery is not curative. A majority of patients develop disease recurrence at or above the anastomosis. Subclinical endoscopically identifiable recurrence precedes the development of clinical symptoms; identification and treatment of early mucosal recurrence may therefore prevent clinical recurrence. Therapy to achieve mucosal healing should now be the focus of postoperative therapy. A number of clinical risk factors for the development of earlier postoperative recurrence have been identified, and reasonable evidence is now available regarding the efficacy of drug therapies in preventing recurrence. This evidence now needs to be incorporated into prospective treatment strategies.

Dietary α-linolenic acid-rich formula reduces adhesion molecules in rats with experimental colitis

OBJECTIVE

The ω-3 polyunsaturated fatty acid therapy in inflammatory bowel disease is focused on the effects on fish oil-derived polyunsaturated fatty acids. We speculated that a vegetal oil rich in α-linolenic acid (ALA) might also inhibit colitis. Therefore, we evaluated whether dietary ALA would decrease the expression of adhesion molecules by inducing the protective enzyme heme oxygenase-1 (HO-1) in a rat colitis model.

METHODS

Colitis was induced at day 0 by an intrarectal injection of 2-4-6-trinitrobenzen sulfonic acid (TNBS), whereas control rats received the vehicle. Rats were fed an ALA-rich formula 450 mg · kg⁻¹ · d⁻¹, whereas the other colitic group (TNBS) and the control group were fed an isocaloric corn oil formula for 14 d (from day -7 to day 7). The colonic expressions of intercellular adhesion molecule-1 (ICAM-1), vascular cell adhesion molecule-1 (VCAM-1), vascular endothelial growth factor A receptor-2 (VEGFR2), and HO-1 were studied by immunohistochemistry.

RESULTS

The ALA-rich diet significantly decreased the expression of ICAM-1, VCAM-1, and VEGFR-2 compared the TNBS group, but it did not affect the expression of HO-1.

CONCLUSION

A vegetal ALA-rich formula decreases the expression of ICAM-1, VCAM-1, and VEGFR-2 and independently of HO-1 in rats with TNBS-induced colitis. Further studies are required to evaluate its therapeutic potential in inflammatory bowel disease as an alternative to fish oil.

Th17 cell accumulation is decreased during chronic experimental colitis by (n-3) PUFA in Fat-1 mice

During colon inflammation, Th17 cells and immunosuppressive regulatory T cells (Treg) are thought to play promotive and preventative roles, respectively. Dietary (n-3) PUFA favorably modulate intestinal inflammation in part by downregulating T-cell activation and functionality. We used the Fat-1 mouse, a genetic model that synthesizes long-chain (n-3) PUFA de novo, to test the hypothesis that (n-3) PUFA protect against colonic inflammation by modulating the polarization of Treg and Th17 cells during colitis. Male and female wild-type (WT) and Fat-1 mice were administered dextran sodium sulfate (DSS) in the drinking water (2.5%) to induce acute (5 d DSS) or chronic (3 cycles DSS) colitis and the percentage of Treg and Th17 cells residing locally [colonic lamina propria (cLP)] and systemically (spleen) was determined by flow cytometry. The percentage of Treg in either tissue site was unaffected by genotype (P > 0.05); however, during chronic colitis, the percentage of Th17 cells residing in both the spleen and cLP was lower in Fat-1 mice compared to WT mice (P < 0.05). Colonic mucosal mRNA expression of critical Th17 cell cytokines and chemokine receptors (IL-17F, IL-21, and CCR6) were lower, whereas expression of the Th17 cell suppressive cytokine, IL-27, was greater in Fat-1 mice compared to WT mice during chronic colitis (P < 0.05). Moreover, colon histological scores were improved in Fat-1 mice (P < 0.05). Collectively, these results demonstrate for the first time, to our knowledge, that (n-3) PUFA can modulate the colonic mucosal microenvironment to suppress Th17 cell accumulation and inflammatory damage following the induction of chronic colitis.

Hepatocyte growth factor and omega-3-enriched feeds have a synergistic effect on mucosal mass in an animal model of inflammatory bowel disease

BACKGROUND

Hepatocyte growth factor (HGF) decreases intestinal inflammation and cytokine levels in an animal model of inflammatory bowel disease (IBD). Luminal omega-3 (OM-3) is anti-angiogenic, reduces inflammation, and may decrease symptoms in patients with Crohn's disease. This study evaluates the synergism of HGF and OM-3.

METHODS

Twenty adult female transgenic HLA-B27 rats were divided into 4 groups: group 1: regular feeds, IV saline; group 2: OM-3-enriched feeds, IV saline; group 3: regular feeds, IV HGF (150 µg/kg per day); and group 4: OM-3-enriched feeds, IV HGF(150 µg/kg per day). Rats were killed at 14 days after pump placement. Small and large bowel mucosa was harvested, and DNA and protein were extracted and quantified. Statistical analysis was done by analysis of variance with post-hoc Tukey's HSD test.

RESULTS

Content of protein and DNA in the ileum were significantly increased by supplementation of HGF (P < .001, P < .01, respectively) alone. OM-3 significantly increased protein content but not DNA (P = .02, P = 0.3, respectively). Combined, they had a synergistic effect greater than either supplement alone (P = .0001, P = .002, respectively). In the colon, HGF and OM-3 did not significantly increase protein or DNA content individually or together.

CONCLUSIONS

This is the first demonstration of the synergistic effect of a growth factor (HGF) and a dietary supplement (OM-3) in an immunologic model of IBD.

Nutrition and inflammatory bowel disease: primary or adjuvant therapy

PURPOSE OF REVIEW

Our understanding of the importance of nutrition in inflammatory bowel disease (IBD) continues to improve. With increasing evidence or cumulative evidence, this article reviews the current data for the role of nutrition in IBD pathogenesis, disease exacerbation and its use in the treatment of IBD in a clinically relevant context.

RECENT FINDINGS

Irritable bowel syndrome and obesity prevalence is rising, and is increasingly being recognized in patients with IBD. Exclusive enteral nutrition remains highly relevant because of its efficacy and superior side-effect profile, even when considered against new pharmacological treatments, but requires patient motivation. We are now beginning to understand the importance of micronutrients such as iron and vitamin D, which may not only alter the bowel flora but also have an immune-modulatory effect. More recently, a prebiotic and probiotic combination has been used in a randomized trial for the treatment of IBD.

SUMMARY

Macronutrient and micronutrient assessment should be an essential part of nutritional assessment of all patients with IBD. Although research is needed to further our understanding of the immune-modulatory effects of nutrients and supplements, better and more effective therapies combining nutrition and drug treatments like immune-suppressants should be explored.

Profiling the regulatory lipids: another systemic way to unveil the biological mystery

PURPOSE OF REVIEW

The regulatory lipids are a class of bioactive lipids which regulate various important biological processes. Profiling these regulatory lipids is an attractive method to understand the role of these metabolites. This is especially true because most of these regulatory lipids are derived from several important pharmacological targets: cyclooxygenase, lipoxygenase, and cytochrome P450 enzymes. This review highlights the development of methods to profile these regulatory lipids and the recent publications employing these profiling methods.

RECENT FINDINGS

The recent development of methods for the profiling of regulatory lipids target two different directions: to expand coverage for discovery studies (fingerprinting) and to make the quantitative method more accurate, sensitive, and faster for diagnostic or more detailed studies. Recent applications of these profiling methods including assessment of in-vivo drug engagement, pathways crosstalk, and possible mechanisms for side-effects of a withdrawn anti-inflammatory drug rofecoxib are also reviewed here.

SUMMARY

The profiling of regulatory lipids is a useful tool for many investigations. The breadth of coverage, throughput limits with detection, and reproducibility of quantitation are being improved. The resulting data will assist with fundamental investigation, disease biomarker discovery, drug discovery, and drug development.