Introduction

The Monash Pouch diet is a multi-prong diet strategy that theoretically targets ‘correction’ of the microbial metabolic activities, namely excessive sulphide reduction and protein fermentation in the pouch. The diet has previously been shown to be a feasible, highly tolerated and acceptable diet to patients with an ileoanal pouch with signals for clinical improvements¹.

Aims & Methods

The study aimed to assess the effects of the 5-week dietary intervention on the pouch microenvironment via volatile organic metabolites in patients with an ileoanal pouch. In a pilot, open-label study, patients with an ileoanal pouch for ulcerative colitis received dietary advice on a Monash Pouch diet for 5 weeks. They were instructed to restrict osmotically active carbohydrates, total and animal protein, sulphate/sulphite preservatives and carrageenan while increasing oligosaccharide intake. Faecal samples were collected at baseline and at the end of the 5-week intervention and analysed for VOCs using gas-chromatography-mass spectrometry. Changes in VOC were compared particularly for bacterial fermentative metabolites. Results were analysed using Metaboanalyst (version 5.0) and metabolites of interest were defined by paired fold-change analysis.

Results

Eleven patients (6 men, mean age 55 years) completed the dietary intervention and provided faecal samples. Average number of VOCs detected between baseline and post-diet intervention (53 (9) vs 55 (7); p=0.59; paired t-test) were not significantly different. At baseline, percentage occurrence of protein fermentation metabolite was the highest for phenols (9/11, 81%) whereas the branched-chain fatty acids, 2- and 3-methylbutanoic acid (isovalerate) (45% and 64% respectively) and 2-methylpropanoic acid (isobutyrate) (54%), were detected. No volatile sulphur compounds were detected. The dietary intervention saw no significant changes in ethanoate (acetate) (p=0.88), propanoate (propionate) (p=0.44), butanoic (butyrate) (p=0.57) or any of protein fermentation metabolites (p>0.15). Fold-change analysis identified six important features that were altered from pre- to post-intervention. Ethyl-2-methylbutanoate (fold change: 4.07; Log₂ 2.03), 3-isothiocyanatoprop-1-ene (2.01; Log₂ 1.01) increased whilst pentane-2,3-dione (0.48; Log₂ -1.07), propanal (0.49; Log₂ -1.02) and 7-methyl-3-methylideneocta-1,6-diene (0.49; Log₂-1.02) decreased. Of the known bacterial fermentation metabolites, there was a trend for changes in intake of animal protein to correlate with changes in 3-methylbutanoic acid(r=0.57; p=0.07) and a significant correlation between fibre intake and propanoic acid (r=-0.66; p=0.03).

Conclusion

VOC analysis of ileal effluent has provided signals that protein fermentation may not be prominent (low concentrations of metabolites associated with protein fermentation) and that the Monash Pouch diet paradoxically shifted pouch microbial fermentation towards increased proteolytic activities (increased ethyl-2-methylbutanoate), suggesting the dietary strategy may require modification. However, given the small sample size of this cohort, these results should be interpreted with caution and the fold-change data be regarded as clues to VOCs that may be significant in a larger cohort of ileoanal UC pouch patients.

References

1. Ardalan ZS, Yao CK, Gill P et al. Tolerability and effects of a novel dietary strategy(the 5-SURE diet) in patients with an ileoanal pouch: A pilot study. Journal of gastroenterology and hepatology. 2020;35:144.

Disclosure

ZSA: None to declare
KG: None to declare
MS: None to declare
PRG: Consultant or advisory board member for Anatara, Atmo Biosciences, Immunic Therapeutics, Novozymes, Novoviah and Comvita. He has received research grants for investigator‐driven studies from Atmo Biosciences. He holds shares in Atmo Biosciences. His Department financially benefits from the sales of a digital application, booklets and online courses on the FODMAP diet.
CP: None to declare
CKY: CK is a recipient of the Angela McAvoy Crohn's Colitis Australia research scholarship. She also works in a department that financially benefits from the sales of a digital application, booklets and online courses on the FODMAP diet.

Introduction

Recent research has shown that there is considerable interest in studying inflammatory bowel diseases (IBD) due to the potential for dietary interventions to be used as a therapeutic approach for their onset and progression. Evidence suggests that Western-style diets, with high intake of processed foods, food additives, red meat, and animal fat, have been associated with an increased risk of IBD.

Aims & Methods

The purpose of this study is to evaluate the link between an anti-inflammatory exclusion diet and the maintenance of IBD remission, as well as to assess the potential therapeutic advantages of this dietary approach in preserving IBD remission.The inclusion and exclusion criteria were applied to a total of 189 individuals with IBD, with 21 individuals not meeting the criteria. Therefore, 168 eligible patients were enrolled in the study and allocated to either an exclusion diet or a regular diet, based on their personal preference.

Results

A cohort of 84 adult patients with inflammatory bowel disease (IBD) was recruited for the study. The cohort included 47.6% males, with 44 patients having ulcerative colitis (UC) and 40 having Crohn's disease (CD). The intervention group received an exclusion diet consisting of the removal of red and processed meat, fried foods, high-lactose foods, fast food, white bread, sweetened drinks, and vegetable oils rich in omega-6 for a period of 1 year. An equivalent number of IBD patients with similar demographics and disease types formed the control group. The exclusion diet was well tolerated, with 90% of participants adhering to it frequently or always. The study demonstrated that the clinical response was maintained in 80 patients (95.2%) in the intervention group, which was significantly higher than the 72 patients (85.7%) in the control group (p-value=0.036). Although not statistically significant, fecal calprotectin was higher in the control group than in the intervention group at the one-year follow-up interval. Additional information is provided in Table 1.

Conclusion

Patients who adhere to an exclusion diet have the chance of a significantly higher rate of maintenance of clinical remission (95% versus 86% in the control group). A trend toward improvement in inflammation tests was observed in the intervention group, confirming once again that Western-style diet is an important etiological factor in IBD. Therefore, it is recommended that the exclusion, anti-inflammatory diet be presented to all patients diagnosed with IBD as a potential intervention.

Introduction

Inflammatory bowel disease (IBD) is a complex chronic and relapsing inflammatory disorder of the gastrointestinal tract with unclear pathogenesis. Accumulating evidence suggests food emulsifiers as a risk factor for the development of IBD. It is indicated that food emulsifiers carboxymethylcellulose (CMC) can alter gut microbiota and promote intestinal inflammation in IBD under normal diet. Since high-fat diet is the main life scenario for CMC use, little is known about the effect of CMC on colitis model in different high-fat diet.

Aims & Methods

C57/BL6 mice (3-5 weeks old) were randomly divided into three high-fat diet (HFD) groups, which only differed by fat composition (40 %), derived from corn oil (HCO, n-6 polyunsaturated fatty acids), olive oil (HOO, monounsaturated fatty acids) and milk fat (HMF, saturated fatty acids), and exposed to CMC (1.0% w/v) in drinking water for 4 weeks before the establishment of dextran sulfate sodium (DSS) induced acute colitis mice model. Colon inflammation severity was evaluated using survival rate, HE staining, colon length, body weight change and DAI score. Ki67 and TUNEL assays were performed to detect proliferation and apoptosis.

Results

Compared with the CMC+DSS group, the HMF+CMC+DSS group markedly increased survival rate (P=0.013), colon length (P=0.027) and body weight (day4, day5, day6 and day7, P<0.05, respectively), and relieved DAI score (day4 and day6, P<0.05, respectively) and histological damage (P<0.0001). The HOO+CMC+DSS group seemly had no significant difference from the CMC+DSS group. In contrast, the HCO+CMC+DSS group developed more aggressive colitis with increased DAI score (day5, P<0.01) and decreased body weight (day1, day2, day5 and day6, P<0.05, respectively). In terms of maintaining homeostasis of the intestinal barrier, the HMF+CMC+DSS group showed the highest Ki67 (P=0.012, P=0.0002 P=0.042, respectively) and TUNEL positive cells (P=0.324, P<0.0001, P<0.0001, respectively) compared with the CMC+DSS, HOO+CMC+DSS or HCO+CMC+DSS group. Between CMC+DSS and HOO+CMC+DSS or HCO+CMC+DSS group, there was no difference in Ki67 positive cells, while TUNEL positive cells significantly decreased (P=0.002, P=0.008, respectively).

Conclusion

The function of CMC on DSS colitis varies in different high-fat. Unexpectedly, CMC protects against the development of high-milk-fat related colitis by maintaining homeostasis of proliferation and apoptosis.

References

The function of CMC on DSS colitis varies in different high-fat. Unexpectedly, CMC protects against the development of high-milk-fat related colitis by maintaining homeostasis of proliferation and apoptosis.

Disclosure

none

Introduction

Cholesterol is a key lipid involved in maintaining intestinal epithelial cell membrane structure and function. Recent studies suggest that microbiome-derived cholesterol metabolites, like ursodeoxycholic acid (UDCA) and 7-ketolithocholic acid (7-keto-LCA) promote intestinal epithelial repair and enhance Wnt signalling, thereby facilitating the self-renewal of intestinal stem cells (Li et al., Cell Host & Microbes 2024).

Aims & Methods

This study aimed to evaluate the effects of cholesterol-derived microbial metabolites—specifically lithocholic acid (LCA), deoxycholic acid (DCA), ursodeoxycholic acid (UDCA), and 7-keto-LCA—on intestinal epithelial barrier integrity, inflammatory responses, and homeostasis. Primary screening was conducted in Caco-2 monolayers co-treated with pro-inflammatory cytokines IFN-γ and TNF-α for 24 hours to mimic an inflammatory environment. Metabolites were tested at the following concentrations: LCA (10 µM, 50 µM, 75 µM), DCA (10 µM, 100 µM, 200 µM), UDCA (100 µM, 250 µM, 500 µM), and 7-keto-LCA (5 µM, 10 µM, 50 µM, 100 µM). Selected compounds showing significant effects were further validated in 3D intestinal epithelial organoid cultures. Gene expression analysis of key markers—TNF-α, CXCL9 (inflammation), OCLN, TJP1 (barrier integrity), and FGF19, NR0B2 (homeostasis)—was performed using quantitative RT-PCR. Statistical significance was determined using Student’s t-test with a threshold of p ≤ 0.05.

Results

Primary screening on Caco-2 cells revealed that 7-keto-LCA (10µM, 50µM) and LCA (75µM) downregulated the expression of genes encoding inflammatory cytokines (TNF-a and/or CXCL9; p < 0.05) and upregulated the expression of tight junction proteins (OCLN and TPJ1; p < 0.05) and FXR downstream marker (FGF19, p < 0.05). The tested concentrations of DCA and UDCA did not reduce the expression of inflammatory cytokine coding genes and reinstate the expression of tight junction proteins coding genes. For further analysis in 3D intestinal organoid model we selected 7-keto-LCA (10µM). 7-keto-LCA significantly upregulated the expression of NR0B2 (p < 0.05) and showed a tendency to reduce the expression of TNF-α in intestinal organoids (p = 0.12).

Conclusion

7-keto-LCA showed a trend to reduce inflammation and restore homeostasis in intestinal organoid model.
Study has been funded by the Research Council of Lithuania (LMTLT, agreement No. S-MIP-23-101).

References

Li T, Ding N, Guo H, Hua R, Lin Z, Tian H, Yu Y, Fan D, Yuan Z, Gonzalez FJ, Wu Y. A gut microbiota-bile acid axis promotes intestinal homeostasis upon aspirin-mediated damage. Cell Host Microbe. 2024 Feb 14;32(2):191-208.e9. doi: 10.1016/j.chom.2023.12.015.

Introduction

Crohn’s disease (CD) is characterized by chronic intestinal inflammation due to genetic and environmental factors. Microbiome studies have consistently shown dysbiosis in patients with CD. Diet is an important risk factor in the development of CD and may contribute to changes in the gut microbiota (GM). We conducted a prospective diet intervention study in CD patients and compared one time diet counseling versus catered meals that were high fiber (17g/1000 calories) and low fat (20-25% calories from fat) for 8 weeks (w) and followed for a total of 36w.

Aims & Methods

We hypothesized that metaproteomic characterization of the GM in CD in the context of dietary manipulation could edify response to diet intervention therapy. Patients chose to receive diet counseling alone (group 1), catered food for 8 weeks (group 2), or catered food for a patient (group 3P) and a household control (HHC) (group 3C) as well as participate in Dyadic Psychosocial Support (DPS) sessions (group 3P and 3C). A total of 70 patients and 22 HHC were followed prospectively and collected stool at baseline, week 8, and week 36. Samples were processed with a proven pipeline to isolate and digest bacterial proteins to perform LC-MS analysis.¹ Samples with bacterial protein groups lower than 1800 were not included for further analysis. The resulting dataset was processed with the MetaLab 2.3 application to build a sample specific database (SS-DB) from the integrated gene catalog (IGC)-DB.² Taxonomic assignment to identify peptides was performed using the Unipept desktop version.³

Results

The average taxon-specific peptide distribution in the GM, especially at less specific taxonomic levels, did not show a striking difference between the groups at baseline. At the species level, after 8 weeks of a catered diet there was a general reduction of Collinsella aerofaciens that was more marked in groups 2 and 3P than in the HHC in group 3C. Collinsella aerofaciens has been linked to TLR2 activation, pro-inflammatory responses, and CD.⁴ We also observed a continuous increase in Prevotella copri over time in CD patients ultimately resulting in similar patterns as seen in the household controls. P. copri has recently been recognized as an important biomarker for diet improvements in dysbiosis⁵. In particular, there was an increase of proteins associated with carbohydrate metabolic processes in P. copri in the CD patients over time. Large scale annotation of the metaproteins and their related functions is ongoing.

Conclusion

Evidence suggests that a catered high fiber, low fat diet induces a change in the GM of CD patients more than in healthy subjects. The ability to compare the effect of a diet intervention in CD patients versus matched household controls will give additional power to understanding how diet can be used to manipulate the microbiome in the context of dysbiosis.

References

1) Levi Mortera et al. - International Journal of Molecular Science (2022) 23 (24), 15982; 2) Cheng et al. – Microbiome (2017), 5 (1), 157; 3) Verschaffelt et al. – Journal of Proteome Research (2021), 20 (4), 2083-2088; 4) Kwon J. et al. J Am Chem Soc. 2023 Apr 5; 145(13): 7071–7074; 5) Precup & Vodnar - British Journal of Nutrition (2019), 122, 131-140

Introduction

Crohn’s disease (CD) is a chronic inflammatory disorder of the gastrointestinal tract, with its etiology involving genetic, microbial and environmental factors. Dysregulated autophagy, high-fat (HF) diet and abnormal colonization of adherent-invasive E. coli (AIEC) have been identified as risk factors for CD. Physical activity (PA) represents a fundamental intervention that offers significant health benefits and has been associated with a reduced risk of developing various diseases, including CD. Although PA has been shown to induce autophagy in different tissues, exerting beneficial effects for the organism, its impact on autophagy in the intestine and its ability to suppress the deleterious effects of HF diet via the modulation of autophagy have not been investigated.

Aims & Methods

This study aims to (i) explore the influence of PA on the autophagy process in intestinal tissue, and (ii) assess the potential of PA to restore intestinal homeostasis and decrease inflammation caused by HF consumption. Mice deficient for the autophagy-related gene Atg16l1 specifically in intestinal epithelial cells (Atg16l1^flox/floxCreVillin, called by Atg16l1^∆IEC mice) or wild-type mice (WT or Atg16l1^flox/flox) were fed either a control or HF diet for 12 weeks, and then engaged in spontaneous PA on running wheels (active group) or not (sedentary control group) for the same duration. The travelled distance (km), and the speed (m/min) on the wheels were recorded continuously. At the end of the experiment, total fat mass and fat-free mass were measured with echoMRI. The weight of total mesenteric and epididymal adipose tissues were also determined post-mortem. Levels of autophagy markers were assessed by Western blot and qRT-PCR. Intestinal inflammation was assessed by quantification of fecal lipocalin-2 and intestinal pro-inflammatory cytokine levels.

Results

Under HF diet, both Atg16l1^∆IEC and WT mice exhibited substantial weight gain compared to the groups fed the control diet. Spontaneous PA notably attenuated weight gain, particularly in the HF diet-fed groups. Spontaneous PA also diminished the increase in total fat mass and the weight of mesenteric adipose tissue induced by HF consumption, while concurrently augmenting total fat-free mass. HF diet-fed mice exhibited a lower total running distance over the 12 weeks compared to those fed the control diet. Importantly, HF diet consumption led to increased fecal lipocalin-2 level compared to control diet, with a more pronounced effect in Atg16l1^∆IEC versus WT mice, and this level was reduced with spontaneous PA. In the absence of PA, HF diet-fed Atg16l1^∆IEC mice exhibited increased E. coli abundance compared to other mouse groups, and this was not observed in the active groups. Compared to control diet, HF diet led to dysregulation of expression levels of several autophagy markers and autophagy flux in intestinal tissues, and this was corrected by PA. In particular, there was a positive correlation between the total travelled distance and levels of several autophagy-related mRNAs.

Conclusion

Spontaneous PA can correct the dysregulation of autophagy and mitigate intestinal inflammation induced by the HF diet. This suggests that combining spontaneous PA with other therapeutic interventions may be a valuable strategy for CD patients with dysregulated autophagy.