New Microbiota-endocrine Axis in Fructose Malabsorption-caused Visceral Hypersensitivity in Irritable Bowel Syndrome.

Condition(s) studied

Investigational drug(s) / intervention(s)

urine intestinal permeability test or lactulose/mannitol test: Patients will be required to fast for 12 hours and, after emptying their bladder, patients will be asked to drink 100 mL of water containing 10 g of lactulose and 5 g of mannitol. At the patient's inclusion visit, and before the test at the V1 follow-up visit, the patient will be given an explanation with recommendations on their food intake in the 24 hours before and 24 hours during the test (urine collection). Patients will be asked not to drink for 2 hours and not to eat for 5 hours after taking the lactulose and mannitol. An exhaustive urine collection will then be carried out at the patient's home over the 24 hours following the intake of the sugars. The 24-hour urine will be collected in a plastic 24-hour urine container suitable for hospital use. This urine collection will be brought back for visit 2 the following day. On receipt of the urine, the volume of urine will be noted and the appearance of the urine recorded and stored before analysis.

Blood test: A fasting blood sample will be taken in 1 x 4ml EDTA-Aprotinin tube on the morning of the urine test (V1 follow-up visit). The tube will be centrifuged within 15 minutes at 4°C and then aliquoted into 3 x 500μL tubes which will be immediately frozen at -80°C for storage in a biocollection with a view to later measuring gastrointestinal peptides such as CCK, neurotensin and GLP-1.

food diary: On the day of inclusion, all patients were given a food diary to fill in. They will have to fill it in over a period of 4 days, including 1 weekend day. They will be asked to note down all the food they eat during this period, as well as the quantities. The diary will be collected at the V1 visit and will then be analysed by a dietician, who will assess the average daily consumption of fructose in g/d (total fructose consumption, consumption of fructose in excess of glucose, dietary origin of fructose).

stool samples: All patients will have their stools collected. Patients will have their stool collected at home using a collector given to them at the inclusion visit. They will have to bring back the stool within 6 hours for preparation and storage at -80°C.

Microbiota analysis: Stools will be used to analyse the composition of the intestinal microbiota by sequencing amplicons from the V3-V4 region of bacterial 16S rRNA.

Study summary

Irritable bowel syndrome (IBS) affects around 4% of the general population and remains the most common functional bowel disorder. It is defined by the Rome criteria as the presence of abdominal pain associated with transit disorders. The impact on quality of life and the associated costs make it a public health problem.

Visceral hypersensitivity is one of the functional markers of the disease and plays a part in the genesis of symptoms. It could therefore also be a therapeutic target to be explored. Diet and the intestinal microbiota are also part of the recognised pathophysiological mechanisms of this disease. Carbohydrates malabsorbed by the intestine are metabolised by the microbiota, which may contribute to the genesis of symptoms. Among these carbohydrates, fructose appears to be of particular interest. Its absorption capacity is limited, yet fructose consumption is increasing. Fructose malabsorption at a dose of 25 g is present in 22% of IBS patients. Fructose malabsorption is also associated with visceral hypersensitivity. However, the mechanism of this association remains unknown. In models of malabsorbed mice with visceral hypersensitivity, an increase in cholecystokinin was found in the terminal ileum and cecum, suggesting a potential role for this hormone in this model of IBS. However, the underlying mechanism remains poorly understood.

The objective is to determine if microbiota signature is specific of visceral hypersensitivity associated with fructose malabsorption in IBS patients.

60 patients with IBS will be included in the study in 4 groups:

1. n=15 patients with visceral hypersensitivity and fructose malabsorption
2. n=15 patients with visceral hypersensitivity and without fructose malabsorption
3. n=15 patients without visceral hypersensitivity and with fructose malabsorption
4. n=15 patients without visceral hypersensitivity and without fructose malabsorption

All patients will filled validated questionnaires and 4-days food diary. They will also have a urinary permeability test (lactulose/mannitol test) and collected stools samples for microbiota analysis.

Eligibility

Primary outcome measure(s)

• microbiota analysis — from enrollment up to 18 months
  16S RNA gene sequencing
• metabolites analysis — from enrollment up to 18 months
  Mass spectrometry-based metabolomics

Trial sites (1)

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