Ileal and colonic fatty acid profiles in patients with active Crohn's disease

Evaluation of the fatty acid-based erythrocyte membrane lipidome in cats with food responsive enteropathy, inflammatory bowel disease and low-grade intestinal T-cell lymphoma

Feline chronic enteropathies (FCE), include food-responsive-enteropathy (FRE), inflammatory bowel disease (IBD), and low-grade intestinal T-cell lymphoma (LGITL), and are common causes of chronic gastrointestinal signs in cats. Distinguishing between different subgroups of FCE can be challenging due to the frequent overlap of anamnestic, clinical, and laboratory data. While dysregulation in lipid metabolism has been reported in humans and dogs with chronic IBD, similar changes in cats are not yet completely understood. Assessing the fatty acid (FA) profile of red blood cell (RBC) membranes offers a valuable method for evaluating the quantity and quality of structural and functional molecular components in the membranes. Therefore, this study aimed to examine the FA composition of RBC membranes in FCE in comparison to healthy cats (HC). Gas-chromatography was used to quantitatively analyze a cluster of 11 FA, and based on these results, parameters of lipid homeostasis and enzyme activity indexes were calculated. A total of 41 FCE cats (17 FRE, 15 IBD, 9 LGITL) and 43 HC were enrolled. In FCE cats, the values of docosapentaenoic acid (p = 0.0002) and docosahexaenoic acid (p = 0.0246), were significantly higher, resulting in an overall increase in ω-3 polyunsaturated fatty acids (PUFA) (p = 0.006), and that of linoleic acid (p = 0.0026) was significantly lower. Additionally, FCE cats exhibited an increased PUFA balance (p = 0.0019) and Δ6-desaturase index (p = 0.0151), along with a decreased ω-6/ω-3 ratio (p = 0.0019). No differences were observed among cats affected by FRE, IBD and LGITL. Like humans and dogs, the results of this study indicate that FCE cats also display changes in their FA lipid profile at the level of the RBC membrane. The non-invasive analysis of RBC membrane shows promise as a potential tool for gaining a better understanding of lipid imbalances in this disease.

Aged oolong tea alleviates dextran sulfate sodium-induced colitis in mice by modulating the gut microbiota and its metabolites

In this study, the mechanism of aged oolong tea (AOT) to alleviate colitis was investigated in terms of microbiome, metabolome, and fecal microbiota transplantation (FMT). AOT storage period could alleviate colitis in mice and there were some differences in AOT between storage periods, especially AOT-10. AOT improves UC by modulating oxidative stress and inflammatory factors and upregulating intestinal tight junction protein expression (Occludin, Claudin-1, ZO-1 and MUC2), which is associated with the recovery of gut microbiota. FMT and targeted metabolomics further demonstrate that the anti-inflammatory effects of AOT can reshape the gut microbiota through faecal bacterial transfer. Anti-inflammatory effects are exerted through the stimulation of metabolic pathways associated with amino acid, fatty acid and bile acid metabolites. Importantly, the study identified key bacteria (e.g., Sutterella, Clostridiaceae_Clostridium, Mucispirillum, Oscillospira and Ruminococcus) for the development and remission of inflammation. Conclusively, AOT may have great potential in the future adjuvant treatment of colitis.

Fatty acids and lipid mediators in inflammatory bowel disease: from mechanism to treatment

Inflammatory Bowel Disease (IBD) is a chronic, relapsing inflammatory disorder of the gastrointestinal tract. Though the pathogenesis of IBD remains unclear, diet is increasingly recognized as a pivotal factor influencing its onset and progression. Fatty acids, essential components of dietary lipids, play diverse roles in IBD, ranging from anti-inflammatory and immune-regulatory functions to gut-microbiota modulation and barrier maintenance. Short-chain fatty acids (SCFAs), products of indigestible dietary fiber fermentation by gut microbiota, have strong anti-inflammatory properties and are seen as key protective factors against IBD. Among long-chain fatty acids, saturated fatty acids, trans fatty acids, and ω-6 polyunsaturated fatty acids exhibit pro-inflammatory effects, while oleic acid and ω-3 polyunsaturated fatty acids display anti-inflammatory actions. Lipid mediators derived from polyunsaturated fatty acids serve as bioactive molecules, influencing immune cell functions and offering both pro-inflammatory and anti-inflammatory benefits. Recent research has also highlighted the potential of medium- and very long-chain fatty acids in modulating inflammation, mucosal barriers, and gut microbiota in IBD. Given these insights, dietary intervention and supplementation with short-chain fatty acids are emerging as potential therapeutic strategies for IBD. This review elucidates the impact of various fatty acids and lipid mediators on IBD and delves into potential therapeutic avenues stemming from these compounds.

Colonic mucosal biopsy location can not affect the results of mucosal metabolomics and mucosal microbiota analysis in IBS

Objective

To compare and analyze the mucosal metabolites and mucosal microbiota of different parts of colon in patients with IBS.

Methods

A total of 10 patients with IBS-D and six healthy controls (HC) were enrolled. All enrolled participants underwent two biopsies of the ileocecal and sigmoid colon during colonoscopy. Metabolomic profiling of one piece of tissue was conducted using desorption electrospray ionization-mass spectrometry (DESI-MS), and the gut flora of the other piece was examined using 16S rRNA sequencing. The metabolic profiles and flora of the ileocecal and sigmoid colonic mucosa in each group were further analyzed in this study.

Results

(1) Principal components analysis (PCA) indicated that mucosal metabolites did not differ in different parts of the colon in either the IBS-D or HC groups. (2) In the mucosal microbiome analyses, no differences between the microbiota of the two parts of the colon were found by using Principal Co-ordinates Analysis (PCoA). In IBS group, comparing with sigmoid mucosa, the chao1 richness indice was higher and the Shannon index was lower in the ileocecal mucosa (p = 0.40, p = 0.22). However, in the HC group, microbiome analysis of the ileocecal mucosa showed lower values for Chao 1 and Shannon indices than those of the sigmoid colon mucosa (p = 0.06, p = 0.86). (3) Compared with the HC group, 1,113 metabolic signal peaks were upregulated, whereas 594 metabolites were downregulated in the IBS-D samples. Moreover, the PCA of the metabolites showed significant separation between the IBS-D and HC groups. (4) Chao1 expression was significantly higher in the mucosal microbiota with IBS-D than in the HC (p = 0.03). The Shannon index was lower in IBS-D, but the difference was not statistically significant (p = 0.53). PCoA revealed a significant difference in the microflora structure between the IBS-D and HC groups.

Conclusion

The mucosal metabolic profile and mucosal flora structure of the colon were similar, despite different locations in IBS and healthy subjects. IBS had abnormal colonic mucosal metabolism and flora disturbances.

The Fatty Acid-Based Erythrocyte Membrane Lipidome in Dogs with Chronic Enteropathy

Canine chronic enteropathies (CEs) are inflammatory processes resulting from complex interplay between the mucosal immune system, intestinal microbiome, and dietary components in susceptible dogs. Fatty acids (FAs) play important roles in the regulation of physiologic and metabolic pathways and their role in inflammation seems to be dual, as they exhibit pro-inflammatory and anti-inflammatory functions. Analysis of red blood cell (RBC) membrane fatty acid profile represents a tool for assessing the quantity and quality of structural and functional molecular components. This study was aimed at comparing the FA membrane profile, determined by Gas Chromatography and relevant lipid parameter of 48 CE dogs compared with 68 healthy dogs. In CE patients, the levels of stearic (p < 0.0001), dihomo-gamma-linolenic, eicosapentaenoic (p = 0.02), and docosahexaenoic (p = 0.02) acids were significantly higher, and those of palmitic (p < 0.0001) and linoleic (p = 0.0006) acids were significantly lower. Non-responder dogs presented higher percentages of vaccenic acid (p = 0.007), compared to those of dogs that responded to diagnostic trials. These results suggest that lipidomic status may reflect the "gut health", and the non-invasive analysis of RBC membrane might have the potential to become a candidate biomarker in the evaluation of dogs affected by CE.

Deletion of Stearoyl-CoA Desaturase-1 From the Intestinal Epithelium Promotes Inflammation and Tumorigenesis, Reversed by Dietary Oleate

BACKGROUND & AIMS

The enzyme stearoyl-coenzyme A desaturase 1 (SCD or SCD1) produces monounsaturated fatty acids by introducing double bonds into saturated bonds between carbons 9 and 10, with oleic acid as the main product. SCD1 is present in the intestinal epithelium, and fatty acids regulate cell proliferation, so we investigated the effects of SCD1-induced production of oleic acid in enterocytes in mice.

METHODS

We generated mice with disruption of Scd1 selectively in the intestinal epithelium (iScd1^-/- mice) on a C57BL/6 background; iScd1^+/+ mice were used as controls. We also generated iScd1^-/-Apc^Min/+ mice and studied cancer susceptibility. Mice were fed a chow, oleic acid-deficient, or oleic acid-rich diet. Intestinal tissues were collected and analyzed by histology, reverse transcription quantitative polymerase chain reaction, immunohistochemistry, and mass spectrometry, and tumors were quantified and measured.

RESULTS

Compared with control mice, the ileal mucosa of iScd1^-/- mice had a lower proportion of palmitoleic (C16:1 n-7) and oleic acids (C18:1 n-9), with accumulation of stearic acid (C18:0); this resulted a reduction of the Δ9 desaturation ratio between monounsaturated (C16:1 n-7 and C18:1 n-9) and saturated (C16:0 and C18:0) fatty acids. Ileal tissues from iScd1^-/- mice had increased expression of markers of inflammation activation and crypt proliferative genes compared with control mice. The iScd1^-/-Apc^Min/+ mice developed more and larger tumors than iScd1^+/+Apc^Min/+ mice. iScd1^-/-Apc^Min/+ mice fed the oleic acid-rich diet had reduced intestinal inflammation and significantly lower tumor burden compared with mice fed a chow diet.

CONCLUSIONS

In studies of mice, we found intestinal SCD1 to be required for synthesis of oleate in the enterocytes and maintenance of fatty acid homeostasis. Dietary supplementation with oleic acid reduces intestinal inflammation and tumor development in mice.

Comprehensive genetic study of fatty acids helps explain the role of noncoding inflammatory bowel disease associated SNPs and fatty acid metabolism in disease pathogenesis

Fatty acids and their derivatives play an important role in inflammation. Diet and genetics influence fatty acid profiles. Abnormalities of fatty acid profiles have been observed in inflammatory bowel diseases (IBD), a group of complex diseases defined by chronic gastrointestinal inflammation. IBD associated fatty acid profile abnormalities were observed independently of nutritional status or disease activity, suggesting a common genetic background. However, no study so far has attempted to look for overlap between IBD loci and fatty acid associated loci or investigate the genetics of fatty acid profiles in IBD. To this end, we conducted a comprehensive genetic study of fatty acid profiles in IBD using iCHIP, a custom microarray platform designed for deep sequencing of immune-mediated disease associated loci. This study identifies 10 loci associated with fatty acid profiles in IBD. The most significant associations were a locus near CBS (p = 7.62 × 10^-8) and a locus in LRRK2 (p = 1.4 × 10^-7). Of note, this study replicates the FADS gene cluster locus, previously associated with both fatty acid profiles and IBD pathogenesis. Furthermore, we identify 18 carbon chain trans-fatty acids (p = 1.12 × 10^-3), total trans-fatty acids (p = 4.49 × 10^-3), palmitic acid (p = 5.85 × 10^-3) and arachidonic acid (p = 8.58 × 10^-3) as significantly associated with IBD pathogenesis.

Metabolic phenotyping of an adoptive transfer mouse model of experimental colitis and impact of dietary fish oil intake

Inflammatory bowel diseases are acute and chronic disabling inflammatory disorders with multiple complex etiologies that are not well-defined. Chronic intestinal inflammation has been linked to an energy-deficient state of gut epithelium with alterations in oxidative metabolism. Plasma-, urine-, stool-, and liver-specific metabonomic analyses are reported in a naïve T cell adoptive transfer (AT) experimental model of colitis, which evaluated the impact of long-chain n-3 polyunsaturated fatty acid (PUFA)-enriched diet. Metabolic profiles of AT animals and their controls under chow diet or fish oil supplementation were compared to describe the (i) consequences of inflammatory processes and (ii) the differential impact of n-3 fatty acids. Inflammation was associated with higher glycoprotein levels (related to acute-phase response) and remodeling of PUFAs. Low triglyceride levels and enhanced PUFA levels in the liver suggest activation of lipolytic pathways that could lead to the observed increase of phospholipids in the liver (including plasmalogens and sphingomyelins). In parallel, the increase in stool excretion of most amino acids may indicate a protein-losing enteropathy. Fecal content of glutamine was lower in AT mice, a feature exacerbated under fish oil intervention that may reflect a functional relationship between intestinal inflammatory status and glutamine metabolism. The decrease in Krebs cycle intermediates in urine (succinate, α-ketoglutarate) also suggests a reduction in the glutaminolytic pathway at a systemic level. Our data indicate that inflammatory status is related to this overall loss of energy homeostasis.

The Mediterranean diet: effects on proteins that mediate fatty acid metabolism in the colon

A Mediterranean diet appears to have health benefits in many domains of human health, mediated perhaps by its anti-inflammatory effects. Metabolism of fatty acids and subsequent eicosanoid production is a key mechanism by which a Mediterranean diet can exert anti-inflammatory effects. Both dietary fatty acids and fatty acid metabolism determine fatty acid availability for cyclooxygenase- and lipoxygenase-dependent production of eicosanoids, namely prostaglandins and leukotrienes. In dietary intervention studies and in observational studies of the Mediterranean diet, blood levels of fatty acids do reflect dietary intakes but are attenuated. Small differences in fatty acid levels, however, appear to be important, especially when exposures occur over long periods of time. This review summarizes how fat intakes from a Greek-style Mediterranean diet can be expected to affect fatty acid metabolizing proteins, with an emphasis on the metabolic pathways that lead to the formation of proinflammatory eicosanoids. The proteins involved in these pathways are ripe for investigation using proteomic approaches and may be targets for colon cancer prevention.

Metabolic phenotyping of the Crohn's disease-like IBD etiopathology in the TNF(ΔARE/WT) mouse model

The underlying biochemical consequences of inflammatory bowel disease (IBD) on the systemic and gastrointestinal metabolism have not yet been fully elucidated but could help to better understand the disease pathogenesis and to identify tissue-specific markers associated with the different disease stages. Here, we applied a metabonomic approach to monitor metabolic events associated with the gradual development of Crohn's disease (CD)-like ileitis in the TNF(ΔARE/WT) mouse model. Metabolic profiles of different intestinal compartments from the age of 4 up to 24 weeks were generated by combining proton nuclear magnetic resonance ((1)H NMR) spectroscopy and liquid chromatography-mass spectrometry (LC-MS). From 8 weeks onward, mice developed CD similar to the immune and tissue-related phenotype of human CD with ileal involvement, including ileal histological abnormalities, reduced fat mass and body weight, as well as hallmarks of malabsorption with higher energy wasting. The metabonomic approach highlighted shifts in the intestinal lipid metabolism concomitant to the histological onset of inflammation. Moreover, the advanced disease status was characterized by a significantly altered metabolism of cholesterol, triglycerides, phospholipids, plasmalogens, and sphingomyelins in the inflamed tissue (ileum) and the adjacent intestinal parts (proximal colon). These results describe different biological processes associated with the disease onset, including modifications of the general cell membrane composition, alteration of energy homeostasis, and finally the generation of inflammatory lipid mediators. Taken together, this provides novel insights into IBD-related alterations of specific lipid-dependant processes during inflammatory states.

New insights into the role of fatty acids in the pathogenesis and resolution of inflammatory bowel disease

Dietary and endogenously modified lipids modulate inflammation by functioning as intra- and intercellular signaling molecules. Proinflammatory lipid mediators such as the eicosanoids compete against the signaling actions of newly discovered modified fatty acids that act to resolve inflammation. In inflammatory bowel disease, multiple aberrancies in lipid metabolism have been discovered, which shed further light on the pathogenesis of intestinal inflammation. Mechanisms by which lipids modulate inflammation, abnormalities of lipid metabolism in the setting of inflammatory bowel disease, and potential therapeutic application of lipid derivatives in this setting are discussed.

Crohn's disease: evidence for involvement of unregulated transcytosis in disease etio-pathogenesis

Crohn's disease (CD) is a chronic inflammatory bowel disease. Research has identified genetic predisposition and environmental factors as key elements in the development of the disease. However, the precise mechanism that initiates immune activation remains undefined. One pathway for luminal antigenic molecules to enter the sterile lamina propria and activate an immune response is via transcytosis. Transcytosis, although tightly regulated by the cell, has the potential for transepithelial transport of bacteria and highly antigenic luminal molecules whose uncontrolled translocation into the lamina propria can be the source of immune activation. Viewed as a whole, the evidence suggests that unregulated intestinal epithelial transcytosis is involved in the inappropriate presentation of immunogenic luminal macromolecules to the intestinal lamina propria. Thus fulfilling the role of an early pre-morbid mechanism that can result in antigenic overload of the lamina propria and initiate an immune response culminating in chronic inflammation characteristic of this disease. It is the aim of this paper to present evidence implicating enterocyte transcytosis in the early etio-pathogenesis of CD.

Lipid mapping of colonic mucosa by cluster TOF-SIMS imaging and multivariate analysis in cftr knockout mice

The cftr knockout mouse model of cystic fibrosis (CF) shows intestinal obstruction; malabsorption and inflammation; and a fatty acid imbalance in intestinal mucosa. We performed a lipid mapping of colon sections from CF and control (WT) mice by cluster time of flight secondary-ion mass spectrometry (TOF-SIMS) imaging to localize lipid alterations. Data were processed either manually or by multivariate statistical methods. TOF-SIMS analysis showed a particular localization for cholesteryl sulfate at the epithelial border, C16:1 fatty acid in Lieberkühn glands, and C18:0 fatty acid in lamina propria and submucosa. Significant increases in vitamin E (vE) and C16:0 fatty acid in the epithelial border of CF colon were detected. Principal component analysis (PCA) and partitioning clustering allowed us to characterize different structural regions of colonic mucosa according to variations in C14:0, C16:0, C16:1, C18:0, C18:1, C18:2, C20:3, C20:4, and C22:6 fatty acids; phosphatidylethanolamine, phosphatidylcholine, and phosphatidylinositol glycerolipids; cholesterol; vitamin E; and cholesteryl sulfate. PCA on spectra from Lieberkühn glands led to separation of CF and WT individuals. This study shows for the first time the spatial distribution of lipids in colonic mucosa and suggests TOF-SIMS plus multivariate analyses as a powerful tool to investigate disease-related tissue spatial lipid signatures.

Abnormal glucose, lipid and protein metabolism in patients with Crohn's disease

Inflammatory bowel disease (IBD), consisting of Crohn's disease (CD) and ulcerative colitis (UC), poses a great threat to human health. It results from an inappropriate immune response, in genetically susceptible individuals, to microbial antigens of commensal microorganisms. This paper reviews abnormal glucose, lipid and protein metabolism in patients with CD and highlights the application of metabonomics in biomarker revelation for CD.

An arachidonic acid-enriched diet does not result in more colonic inflammation as compared with fish oil- or oleic acid-enriched diets in mice with experimental colitis

Fish oils (FO) – rich in EPA and DHA – may protect against colitis development. Moreover, inflammatory bowel disease patients have elevated colonic arachidonic acid (AA) proportions. So far, effects of dietary AAv.FO on colitis have never been examined. We therefore designed three isoenergetic diets, which were fed to mice for 6 weeks preceding and during 7 d dextran sodium sulfate colitis induction. The control diet was rich in oleic acid (OA). For the other two diets, 1·0 % (w/w) OA was exchanged for EPA+DHA (FO group) or AA. At 7 d after colitis induction, the AA group had gained weight (0·46 (sem0·54) g), whereas the FO and OA groups had lost weight ( − 0·98 (sem0·81) g and − 0·79 (sem1·05) g, respectively;P < 0·01v.AA). The AA group had less diarrhoea than the FO and OA groups (P < 0·05). Weight and length of the colon, histological scores and cytokine concentrations in colon homogenates showed no differences. Myeloperoxidase concentrations in plasma and polymorphonuclear cell infiltration in colon were decreased in the FO group as compared with the OA group. We conclude that in this mice model an AA-enriched diet increased colonic AA content, but did not result in more colonic inflammation as compared with FO- and OA-enriched diets. As we only examined effects after 7 d and because the time point for evaluating effects seems to be important, the present results should be regarded as preliminary. Future studies should further elucidate differential effects of fatty acids on colitis development in time.

Altered status of antioxidant vitamins and fatty acids in patients with inactive inflammatory bowel disease

BACKGROUND & AIMS

Data regarding the nutritional status, antioxidant compounds and plasma fatty acid (FA) composition in inactive IBD are conflicting. We compared plasma levels of antioxidants and FA of patients with inactive IBD with active IBD and controls.

METHODS

Plasma levels of vitamin C, vitamin E, carotenoids, saturated, monounsaturated and polyunsaturated FA, inflammatory markers and nutritional status were determined after an overnight fast in 132 patients with quiescent IBD (40.6+/-13.2 years, 87F/45M), 35 patients with active disease (37.9+/-12.1 years, 25F/10M) and 45 age- and BMI-matched healthy controls (38.1+/-10.5 years, 39F/6M). Results are expressed as mean+/-SD or median [25th percentile;75th percentile].

RESULTS

Body mass index (BMI) was normal in inactive (23.9+/-4.7 kg/m(2)), active IBD (22.7+/-4.2 kg/m(2)) and controls (22.3+/-1.9 kg/m(2)). Compared with controls patients with quiescent IBD showed significantly decreased plasma levels of carotenoids (1.85 [1.37;2.56] vs 1.39 [0.88;1.87] micromol/L) and vitamin C (62.3 [48.7;75.0] vs 51.0 [36.4;77.6] micromol/L), increased levels of saturated FA (3879 [3380;4420] vs 3410 [3142;3989] micromol/L) and monounsaturated FA (2578 [2258;3089] vs 2044 [1836;2434] micromol/L) and similar levels of vitamin E and polyunsaturated FA. Results in active disease were similar to inactive disease.

CONCLUSION

This study shows that antioxidant status and FA profile in a larger population of IBD patients are disturbed independently from disease activity and despite normal overall nutritional status.

Changes in mucosal fatty acid profile in inflammatorybowel disease and in experimental colitis: a common response to bowel inflammation

BACKGROUND AND AIMS

Plasma polyunsaturated fatty acid profile in patients with inflammatory bowel disease is abnormal. We aimed to assess the mucosal fatty acid pattern in patients with ulcerative colitis and Crohn's disease, and in rats with trinitrobenzene-sulfonic acid (TNB) induced colitis.

METHODS

Fatty acids were measured in colonic mucosa of patients with ulcerative colitis (n = 30), Crohn's disease (n = 21), and healthy controls (n = 13). Likewise, they were assessed in the colonic mucosa of rats with TNB- and sham-colitis.

RESULTS

There was an increase of the end-products (C22:5n3, C22:6n3, C20:4n6, C22:5n6) and a decrease of the precursors (C18:3n3, C18:2n6) of both n3 and n6 polyunsaturated fatty acids in the mucosa of active ulcerative colitis and TNB-colitis. Also, high values of saturated (C16:0, C18:0) and low values of monounsaturated fatty acids (C18:1n9) were observed. Furthermore, the mucosa of active Crohn's disease showed substantial changes in saturated, monounsaturated and essential fatty acids, but not in polyunsaturated fatty acids. Mucosa of patients with inactive disease showed intermediate fatty acid values between the mucosa of active patients and healthy controls.

CONCLUSIONS

Colonic inflammation causes a characteristic modification of the mucosal fatty acid profile which appears to be common to different aetiologies and seems to be related to the degree of inflammation.

Arachidonic acid but not eicosapentaenoic acid (EPA) and oleic acid activates NF-kappaB and elevates ICAM-1 expression in Caco-2 cells

In patients with inflammatory bowel disease (IBD), intestinal activation of the transcription factor NF-κB as well as intercellular adhesion molecule (ICAM)-1 expression, which is involved in recruiting leukocytes to the side of inflammation is increased. Moreover, colonic arachidonic acid (ARA) proportions are increased and oleic acid (OA) proportions are decreased. Fish oils are protective in IBD patients however, a side-by-side comparison between effects of fish oils, ARA and OA has not been made. We therefore, compared effects of eicosapentaenoic acid (EPA) versus ARA and OA on ICAM-1 expression in Caco-2 enterocytes. To validate our model we showed that dexamethasone, sulfasalazine and PPARα (GW7647) or PPARγ (troglitazone) agonists significantly lowered ICAM-1 expression. ICAM-1 expression of non-stimulated and cytokine stimulated Caco-2 cells cultured for 22 days with ARA was significant higher as compared to EPA and OA. Furthermore, ARA increased NF-κB activation in a reporter cell-line as compared to EPA. Antibody array analysis of multiple inflammatory proteins particularly showed an increased monocyte chemotactic protein (MCP)-1 and angiogenin production and a decreased interleukin (IL)-6 and IL-10 production by ARA as compared to EPA. Our results showed that ARA but not EPA and OA activates NF-κB and elevates ICAM-1 expression in Caco-2 enterocytes. It suggests that replacement of ARA by EPA or OA in the colon mucosa might have beneficial effects for IBD patients. Finally, we suggest that the pro-inflammatory effects of ARA versus EPA and OA are not related to PPARγ activation and/or eicosanoid formation.

Lipoprotein docosapentaenoic acid is associated with serum matrix metalloproteinase-9 concentration

BACKGROUND

Polyunsaturated fatty acids (PUFA) are thought to play important roles in inflammation. The n-3 series is considered as anti-inflammatory, and some studies have reported increased plasma n-3 polyunsaturated fatty acid pattern in chronic inflammatory conditions. In this study we sought to clarify relationships of the levels of arachidonic acid and the polyunsaturated n-3 fatty acid compositions of isolated LDL, HDL2 and HDL3 particles with matrix metalloproteinase-9 (MMP-9), a marker of inflammation.

RESULTS

The subjects were divided into two groups: those with lower and those with higher than the median serum MMP-9 concentration. In all lipoprotein fractions, the mean percentage of docosapentaenoic acid (C22:5n-3) was higher in the group of subjects with higher MMP-9 level than in those with lower serum MMP-9 concentration (P < 0.01 for all). Likewise, the ratio of docosapentaenoic acid to arachidonic acid (C20:4n-6) was higher in the subjects with higher MMP-9 compared with the lower MMP-9 group (P < 0.001 for all).

CONCLUSION

So far, the evidence for an anti-inflammatory role of the n-3 PUFA has come from dietary interventions. Our results were obtained from a free-living population and indicate that there is a positive correlation between n-3 docosapentaenoic acid and MMP-9. What had triggered the rise in MMP-9 is not known, since serum level of MMP-9 is raised in many inflammatory conditions. These findings may indicate an increased biosynthesis of n-3 polyunsaturated fatty acids in subclinical inflammation.

Linoleic acid induces interleukin-8 production by Crohn's human intestinal smooth muscle cells via arachidonic acid metabolites

Previously we reported that linoleic acid (LA), but not oleic acid, caused a marked increase in the secretion of IL-8 by Crohn's human intestinal smooth muscle (HISM) cells. Antioxidants inhibited this response, implicating a role for oxidative stress and NF-kappaB, a transcription factor for IL-8 that is activated by oxidative stress. In this study, we examined two mechanisms whereby LA, the dietary precursor for arachidonic acid (AA), could increase the production of IL-8 via activation of AA pathways: 1) by generation of reactive oxygen species by the AA-pathway enzymes to activate NF-kappaB or 2) by AA metabolites. Normal and Crohn's HISM cells were exposed to LA, oxidizing solution (Ox), or oxidizing solution enriched with LA (OxLA). Exposure of cells to Ox or OxLA induced oxidative stress as determined by thiobarbituric acid reactive substances. In normal cells, Ox but not LA activated NF-kappaB as determined by transfection experiments and Western blot. In Crohn's cells, NF-kappaB was spontaneously activated and was not further activated by Ox or LA. In contrast, TNF-alpha markedly increased activation of NF-kappaB in both normal and Crohn's cells. These results indicated that LA did not increase IL-8 by activating NF-kappaB, so we evaluated the second mechanism of an effect of AA metabolites. In normal cells, OxLA, but not LA, markedly stimulated IL-8, whereas in Crohn's cells, both OxLA and LA stimulated IL-8. OxLA, also stimulated production of AA metabolites leukotriene B(4) (LTB(4)), PGE(2), and thromboxane B(2) (TXB(2)) by normal and Crohn's cells. To determine whether AA metabolites mediated the IL-8 response, cells were treated with OxLA plus indomethacin (Indo), a cyclooxygenase inhibitor, and nordihydroguaiaretic acid (NDGA), a lipoxygenase inhibitor. Both Indo and NDGA blocked the IL-8 response to OxLA. To determine more specifically a role for AA metabolites, AA was used. Similar to OxLA, OxAA stimulated production of IL-8 and AA metabolites. Pinane thromboxane, a selective thromboxane synthase inhibitor and receptor blocker, inhibited OxAA stimulation of TXB(2) and IL-8 in a dose-response manner. MK886, a selective 5-lipoxygenase inhibitor, inhibited OxAA stimulation of LTB(4) and IL-8 also in a dose-response manner. Analysis of specific gene products by RT-PCR demonstrated that HISM cells expressed receptors for both thromboxane and LTB(4). We conclude that AA metabolites mediated the IL-8 response to LA in HISM cells. Both cyclooxygenase and lipoxygenase pathways were involved. LA did not increase IL-8 by activating NF-kappaB, but NF-kappaB appeared to be involved, because LA increased IL-8 only in situations where NF-kappaB was activated, either spontaneously in Crohn's cells or by Ox in normal cells. We speculate that AA metabolites increased IL-8 production by enhancing NF-kappaB-dependent transcription of IL-8.

Bile composition in inflammatory bowel disease: ileal disease and colectomy, but not colitis, induce lithogenic bile

BACKGROUND

Inflammatory bowel disease is a risk factor for gall-bladder stones, but there is controversy about the composition of these stones and whether such patients develop lithogenic bile.

METHODS

In 54 gallstone-free inflammatory bowel disease patients and 13 non-inflammatory bowel disease patients with cholesterol-rich gallstones, we measured the biliary cholesterol saturation indices, nucleation times and bilirubin concentrations, and determined the bile acid composition and molecular species of phosphatidylcholine, in gall-bladder bile.

RESULTS

Patients with Crohn's colitis or ulcerative colitis had less saturated bile (mean cholesterol saturation index, 0.9) and longer nucleation times (median, 21 days) than those with ileal Crohn's disease (1.5; 14 days) or those who had undergone colectomy (1.6; 5 days). In patients with ileal Crohn's disease, the mean biliary bilirubin concentration was two- to three-fold higher than that in the other groups, and was associated with a decrease in the percentage of biliary deoxycholate and an increase in the percentage of ursodeoxycholate, compared with disease controls, but phosphatidylcholine species were similar.

CONCLUSIONS

Patients with small bowel Crohn's disease, or who have undergone colonic resection, have supersaturated bile and an increased risk of cholesterol gallstone formation. In patients with ileal disease, the presence of high biliary bilirubin concentrations and low percentage of deoxycholic acid may also favour the formation of mixed, pigment-rich, gallstones.

Review: the role of omega 3 fatty acids in intestinal inflammation

The role of polyunsaturated fatty acids (PUFAs) in inflammatory lesions of the intestines is the subject of increasing research. This review begins with a background discussion of the source, elongation, and desaturation of PUFAs, as well as the role they have played in the human diet through evolution. The available data and hypotheses as to how manipulation of PUFAs might effect the various components of the immune system are then provided. Possible mechanisms by which PUFAs result in immunomodulation include alterations in eicosanoid synthesis, membrane fluidity, signal transduction, intraluminal bacteria, and gene expression. Attention is then turned to the known effects that these polyunsaturated fatty acids have on the various individual components of the immune system including lymphocytes, neutrophils, and antigen presenting cells, as well as the immunoregulatory process of apoptosis. Finally, laboratory data on the role of PUFAs in necrotizing enterocolitis, and to a greater extent inflammatory bowel disease, first as demonstrated in animal models of the disease, and second in human studies are then summarized.

Fat intake and fatty acid profile in plasma phospholipids and adipose tissue in patients with Crohn's disease, compared with controls

OBJECTIVES

Fatty acid metabolism is involved in the immune response and inflammation processes in patients with Crohn's disease (CD). Fatty acid changes may be relevant to the clinical course of the disease. The aim of this study was to compare the qualitative and quantitative fat intake and fatty acid composition of plasma phospholipids and adipose tissue in a defined population of CD patients with those in matched controls.

METHODS

Dietary fat intake and fatty acid profile of plasma phospholipids and adipose tissue were assessed in two patient populations: 20 patients with recently diagnosed CD and 32 patients with longstanding (> 10 yr) CD clinically in remission, matched for age and gender with healthy controls.

RESULTS

We observed no significant differences in quantitative or qualitative fat intake between CD patients and controls. Percentages of linoleic acid and alpha-linolenic acid in plasma phospholipids or adipose tissue were not significantly different between patients and controls. However, we observed a significantly (p < 0.05) lower percentage of the sum of the n-3 fatty acids, with significantly (p < 0.01) higher levels of clupanodonic acid (22:5n-3) and significantly (p < 0.05) lower levels of docosahexaenoic (22:6n-3) and arachidonic acid (20:4n-6). The aberrant fatty acid profile was more evident in patients with longstanding CD than in patients with recently diagnosed CD.

CONCLUSION

The aberrant fatty acid profile found in these CD patients is a result of altered metabolism rather than of essential fatty acid malabsorption. The reported findings may be important in the pathophysiology of CD and hence in the choice of fatty acids to be used when therapeutic supplementation is considered in CD patients.

Changes in plasma and colonic mucosa fatty acid profiles in rats with ulcerative colitis induced by trinitrobenzene sulfonic acid

Polyunsaturated fatty acids have a key role in the pathogenesis of inflammatory bowel disease since some of the arachidonic acid-derived eicosanoids have been found to be increased in inflamed intestinal mucosa in the acute phase of human disease. The aim of this study was to prospectively assess plasma and colon mucosa fatty acid patterns in rats with experimental ulcerative colitis. Twenty rats were treated with trinitrobenzene sulfonic acid and 20 with NaCl; two groups were killed after one week and two after two weeks to evaluate colon damage. Plasma was obtained by aortic puncture and colonic mucosa was scraped off and the fatty acid pattern was determined by gas-liquid chromatography. Total, saturated, and monounsaturated plasma fatty acids were significantly higher in both periods of ulcerative colitis as compared to controls. Plasma n-6 fatty acids were increased after treatment, but no significant changes were observed concerning to n-3 fatty acids. With regard to colon mucosa, saturated and monounsaturated fatty acids did not change because of the disease; however, n-6 fatty acids decreased in the first week and increased in the second week and n-3 fatty acids were increased. Changes on the fatty acid distribution in plasma did not parallel to those of colonic mucosa except for 22:6(n-3). We have also found that experimental ulcerative colitis induced by trinitrobenzene sulfonic acid reproduces many of the features related to changes in plasma and colon mucosa fatty acids observed in the human disease.

Plasma and mucosal fatty acid pattern in colectomized ulcerative colitis patients

Patients with inflammatory bowel disease (IBD) have increased plasma n3 polyunsaturated fatty acids (PUFAs), which in ulcerative colitis (UC) patients persists six months after colectomy, suggesting a primary abnormality in fatty acid (FA) metabolism in IBD. This finding needed to be confirmed in a larger series of UC long-term colectomized patients. We aimed to assess the plasma FA pattern in UC colectomized patients with either Brooke's ileostomy (UC-BI) or ileal pouch anal anastomosis (UC-IPAA) and the mucosal FA pattern in the ileal reservoir of the UC-IPAA patients. Plasma FAs were assessed in 63 UC colectomized patients (31 with BI and 32 with IPAA) and 30 controls. In 26 UC-IPAA (8 with pouchitis and 18 without pouchitis) and in 13 healthy controls gut mucosal FAs were also investigated. FAs were detected by capillary column gas-liquid chromatography. Increased levels of saturated fatty acids (SFAs) and decreased percentages of monounsaturated fatty acids (MUFAs) were observed in both groups of patients. There were no changes in plasma n3 and n6 PUFAs. The mucosal FA pattern of the ileal reservoir consisted of increased long-chain PUFAs, specially n6 PUFA, and a decrease of their essential precursors. High percentages of SFAs and low percentages of MUFAs were also seen. The plasma FA profile previously described in IBD is not observed long-term after colectomy in UC, suggesting that it is related with the presence of inflamed intestine. High concentrations of SFAs and decreased percentages of MUFAs might represent early events in disturbed FA metabolism in IBD. The changes in FAs of the ileal reservoir, which closely resemble those found in human and experimental IBD, probably represent a common pattern of intestinal inflammation.

Serum n3 polyunsaturated fatty acids are depleted in Crohn's disease

To determine fatty acid patterns in Crohn's disease, we measured various serum fatty acids by gas chromatography in 20 patients with the disease and compared them with those in 18 healthy controls. All the patients had been free from any nutritional supplementation during preceding six months or had no history of intestinal resection. Eight of the patients were affected in the small bowel only, three in the large bowel only, and the remaining nine in both the small and large bowel. Both serum concentrations and percentages of C20:4n6, C20:5n3, C22:0, C22:6n3, total n3 polyunsaturated fatty acids, and total polyunsaturated fatty acids were lower in the patients than in the controls. Both essential fatty acids (C18:2n6, C18:3n3) and C20:3n9 levels were not different between the two groups. Among nine fatty acids that correlated with the Crohn's disease activity index, C20:5n3 and total n3 polyunsaturated fatty acids showed the most significant negative correlations. These findings suggest that essential fatty acid deficiency rarely occurs in Crohn's disease and also that n3 polyunsaturated fatty acids may be relevant to the activity of the disease.

Polyunsaturated fat in the diet may improve intestinal function in patients with Crohn's disease

To investigate the effect of increasing dietary polyunsaturated fat intake on fat absorption in Crohn's patients, normal subjects and subjects with inactive Crohn's disease consumed a high polyunsaturated to saturated fat ratio diet. Subjects participated in breath tests before and after six months of a high polyunsaturated to saturated (P/S) fat ratio diet to measure their response to [1-13C] 10:0 and [1-13C] 16:0 ingested with a test meal. Whole body absorption-oxidation of C10:0 was not affected by the diet treatment. Before diet treatment, whole body absorption-oxidation of C16:0 in Crohn's patients was 80% of that observed for control subjects. After consuming a high polyunsaturated to saturated fatty acid ratio diet, subjects increased oxidation of C16:0 by 85% compared to before the diet treatment period. It is concluded that (1) absorption of labelled C16:0 from a test meal is reduced in Crohn's patients, and (2) consumption of a high polyunsaturated to saturated fatty acid ratio diet improves the utilization of dietary C16:0 by Crohn's patients.

Influence of heated and nonheated partially hydrogenated dietary fats on ileal chyme fat and fatty acid composition of ileal mucosa in pigs

In this study the effects of partially hydrogenated chemically processed fats (CPF) and non-CPF on the ileal chyme fat and the fatty acid (FA) profile of the ileal mucosa and the subcutaneous tissue were analyzed. Samples were collected via an ileocutaneous fistula. For three months pigs were fed a control meal or diets containing either non-CPF high on 16:0, non-CPF high on 18:2 n6, CPF with 50% trans-18:1 or 20% trans-18:1. The latter fat was used after heat treatment. With both CPF diets, the fat content in the ileal chyme was three times higher than with non-CPF. In contrast to subcutaneous tissue reflecting dietary composition, changes in FA profile of ileal mucosa were restricted. Each non-CPF resulted in an increase of the characteristic major dietary FA. Both CPF increased the mucosal trans-FA percentage from 0 to 12% on average, although dietary composition was different. This study suggests: (1) less effects of trans-FA on the regulation of intraluminal fat load compared to saturated and cis-polyunsaturated FA, and (2) higher mucosal incorporation of trans-FA with heated CPF. This may play a role in the development of epithelial lesions in the ileum, which are known following ingestion of these fats.

[What is the role of nutrition in ulcerative colitis? A contribution to the current status of diet therapy in treatment of inflammatory bowel diseases]

Nutritional therapy for ulcerative colitis (UC) is controversial. Studies are usually designed to investigate total parenteral (TPN) or total enteral nutrition (TEN), and before these can be compared it is necessary to differentiate between the different therapeutic aims. The aims of artificial nutritional support in patients with UC are the readjustment of the nutritional status, possible remission of disease activity, and decrease in the incidence of surgical intervention or postoperative complication. Owing to the heterogeneity of the results published so far, it is still difficult to compare studies. Nevertheless, they indicate that the extent and severity of the colitis and the patient selection are of paramount importance in the implementation of nutritional therapy. Positive effects of TPN reported from non-controlled studies were not confirmed by controlled trials. Moreover, TPN was no more effective than an oral diet. Regarding remission rates or operative interventions needed, TPN had more side effects than and no defined advantages over TEN. TEN seems to be useful for certain patients. In some patients with UC, it seems to be accompanied by fewer postoperative complications. However, a definitive conclusion on the effects of TEN or TPN is not yet possible. In this context, certain fatty acids may have an important role in the treatment of UC. In prospective, randomized and controlled studies omega-3 fatty acids were found to be therapeutically useful. A reduction of the steroid doses needed is particularly important. Another therapeutic approach in distal UC is seen in the rectal administration of short chain fatty acids.