Modulation of intestinal barrier function and inflammation via butyrate-promoting dietary fibre

Project Information

FIBCOLIT

Grant agreement ID: 896263

DOI

10.3030/896263

Project closed

EC signature date 23 March 2020

Start date 1 September 2021

End date 31 August 2023

Funded under

• EXCELLENT SCIENCE - Marie Skłodowska-Curie Actions

Total cost

€ 203 852,16

EU contribution

€ 203 852,16

Coordinated by

OREBRO UNIVERSITY
Sweden

Periodic Reporting for period 1 - FIBCOLIT (Modulation of intestinal barrier function and inflammation via butyrate-promoting dietary fibre)

Reporting period: 2021-09-01 to 2023-08-31

Summary of the context and overall objectives of the project

Intestinal barrier function refers to the intestinal epithelium’s task of restricting the passage of noxious substances into circulation. Anomalies in the mechanisms that uphold intestinal barrier function can lead to increased passage of luminal molecules into circulation. This increase in intestinal permeability to bacterial antigens can subsequently activate pro-inflammatory signalling. Increased intestinal permeability is frequently observed in patients with disorders characterised by intestinal inflammation, such as inflammatory bowel diseases (IBDs, Crohn’s disease and ulcerative colitis) and microscopic colitis (MC). Although dietary fibres have shown promise in alleviating the symptoms of IBD, the underlying biological mechanisms remain elusive. One such mechanism could be certain dietary fibres’ capability to modify the composition and functionality of intestinal microbiota by promoting the growth of butyrate-producing bacteria. Indeed, studies have shown that IBD and MC patients display decreased abundance of butyrate-producing bacteria. Butyrate is the main energy source for colonocytes, but it also regulates cell proliferation and gene expression, strengthens intestinal barrier function, and induces anti-inflammatory signalling. Thus, increasing luminal butyrate availability via butyrate-promoting dietary fibre potentially provides a non-pharmaceutical option to restore intestinal homeostasis in certain diseases.

The overall aim of this study is to examine whether and how a 6-week intervention with a dietary fibre known to promote luminal butyrate production affects measures intestinal barrier function, intestinal inflammation, intestinal microbiota, and gastrointestinal symptoms in MC patients. This objective has considerable importance given that 1) the last 20 years have seen a significant global increase in the incidence and prevalence of inflammatory bowel diseases (IBD) , and 2) intestinal inflammation, even at a low grade, drives the development of systemic inflammation in obesity and obesity-related disorders, such as metabolic syndrome and type 2 diabetes. Considering the personal, societal, and economic burden of these diseases, there is a growing need for a better understanding of the physiological mechanisms that maintain and modulate intestinal homeostasis. Should DF supplementation prove effective at restoring intestinal homeostasis in MC, it could potentially offer a non-pharmaceutical option to disease prevention and management as well as reveal new insights about the pathophysiological mechanisms that promote intestinal inflammation.

Work performed from the beginning of the project to the end of the period covered by the report and main results achieved so far

To reach the project aims, we set up a single-centre, randomised, double-blinded, placebo-controlled intervention clinical study with a parallel design and two study arms. Patients with a confirmed diagnosis of microscopis colitis were recruited to trial and randomised to receive either a dietary fibre supplement or a placebo supplement. Both supplements were added to the participants' habitual diet as a powder (2 * 12 g per day for 6 weeks). Biological samples (blood, faecal, urine) were collected as baseline and after the intervention period. The participants were also asked to fill out specific questionnaires about the symptoms, mental health, and general well-being.

Intestinal barrier function was assessed in vivo by a standardised, non-invasive multi-sugar test that simultaneously measures gastroduodenal, small intestinal, colonic, and whole gut permeability. The test is based on the urinary excretion of five different ingested sugar probes: sucrose, rhamnose, lactulose, sucralose, and erythritol. The concentrations of these sugars are analysed by high-pressure liquid chromatography (HPLC) in urine samples collected over 24 h. Intestinal barrier function was also assessed using indirect markers from blood, namely lipopolysaccharide-binding protein (LBP) and intestinal fatty-acid binding protein (I-FABP).

The effects on inflammatory parameters were studied extensively by utilizing commercially available multiplex assays. Overall, we analysed the serum concentrations of 30 individual inflammatory parameters consisting of proinflammatory cytokines, anti-inflammatory cytokines, and chemokines. Furthermore, to examine changes in the degree of intestinal inflammation, we analysed the levels of faecal calprotectin.

The composition of intestinal microbiota before and after the intervention was assessed via shotgun metagenomics sequencing. This work was carried out by Clinical Genomics Örebro.

The effects on the patients’ symptoms, overall quality of life, and well-being were analysed by a series of validated questionnaires. The patients were asked to fill out a total of four questionnaires at baseline and after the intervention: the Gastrointestinal Symptom Rating Scale (GSRS), the Hospital Anxiety and Depression Scale (HADS), the EuroQul questionnaire, and the Short Health Scale (SHS). In addition, the patients were asked to keep a daily diary about their bowel habits (frequency and consistency) throughout the intervention period. The overall scores from each questionnaire were calculated to measure any possible changes in gastrointestinal symptom severity (GSRS), anxiety (HADS-A), depression (HADS-D), overall quality of life (EuroQul), and disease-related well-being (SHS).

Overall, the dietary fibre supplementation did not affect the patients' intestinal barrier function, markers of inflammation, and disease symptoms compared to the placebo supplementation. Due to delays in patient recruitment which has delayed the sample analyses, we are still performing comprehensive statistical analyses. These analyses will include the integration of the measured variables to create one of the most comprehensive datasets on microscopic colitis patient cohort.

The delays in patient recruitment has also delayed the project result dissemination. So far, the project results have been presented at one national and one international congress. The project results will also be presented at an upcoming European conference. The project results will be published as scientific publications when full data analyses have been completed.

Progress beyond the state of the art and expected potential impact (including the socio-economic impact and the wider societal implications of the project so far)

The data of the project forms one the most comprehensive data set on microscopic colitis patients. To our knowledge, this study is one of the first to examine the intestinal microbiota of microscopic colitis patients via shotgun sequencing. Thus, the data set also contains novel information about the virome and mycobiome of these patients. Furthermore, combining these data with measurements on in vivo intestinal permeability and several inflammatory markers as well as gastrointestinal symptoms will possibly reveal novel insights of the pathophysiological mechanisms behind chronic intestinal inflammation. The overall data set could benefit researchers working on this field in the future. The project results will potentially be of interest to nutritionists, medical doctors working with this patient group, scientists in the field of nutrition, and scientists working with similar methodology. The results could also interest patients living with the disease as they might have severe symptoms and are interested in scientific findings about the disease. These groups have been targeted in current communication activities and they will continued when the project results are published.

Study hypothesis