Objective: This study aims elucidate the pathophysiological link between the environment in the colon (mainly the microbiota), the local immune system and activation of the enteric nervous system in patients with post-infectious IBS (PI-IBS) and microscopic colitis (MC) with special emphasis on microbial-mucosa interactions and evaluation of the effect on the immune activation/response as well as how afferent gut-brain signalling leads to abdominal discomfort.

Method: The project is based on data from three cohorts of patients, one with PI-IBS and one with MC as well as a gender- and age-matched cohort of healthy individuals. Measurement of perceived sensitivity in the gut will be evaluated by pain-response under mechanical stress using a barostat. The HIT (Human intestinal Tissue)-Chip array will be used to characterize the diversity, stability and functionality of the intestinal microbiota on mucosa level, giving a clue to the interactions with the host and insight to changes leading to the development of the two diseases.

Immunohistochemistry and flowcytometry will be used to analyse the location, frequency and phenotype characteristics of lymphoid- and mast cells. Functional analysis of mucosal lymphocytes activated in vitro by products from the intestinal microbiota will be examined by cytokine production using the LuminexTM system. The Ussing chamber technique will allow investigation of the impact of the microbiota and its metabolites on intestinal barrier functions. In this method the sample has access to stressors under standard conditions.

We will make a characterization of lymphocytes, mast cells and gut microflora. Depending on these results we will make stimulations of patient biopsies to find if tissue from patients react differently then patients from healthy.

Inclusion Criteria:

• Over 18 years
• Healthy and not eating any prescription medication except birth control in pill form

Exclusion Criteria:

• Have or had a history of gastrointestinal disease that has required specialist medical care
• Being lactose intolerance
• Have high blood pressure requiring treatment
• Have premenstrual syndrome
• Lose Weight
• Being pregnant or breast-feed

Patients will be recruited from clinic (endoskopimotagningen) at Örebro University Hospital.