The Altitude Inflammatory Bowel Disease Study

Not Applicable

Brief Summary: This is a prospective, controlled and observational study. Participants underwent a 3-hour exposure to hypoxic conditions simulating an altitude of 4,000 meters above sea level (m.a.s.l.) in a hypobaric pressure chamber. Clinical parameters, as well as blood and stool samples and biopsies from the sigmoid colon (by sigmoidoscopy) are collected at subsequent time points. The investigators goal is to evaluate if a 3-hour stay at high altitude (4, 000 m) can alter disease activity and can modulate a pro inflammatory reaction.

Detailed Description: To evaluate the potential influence of hypoxia on the course of IBD on a biomolecular level, and to test the effects of hypoxia under standardized conditions, the investigators initiated a prospective and controlled investigation in healthy controls and IBD patients in stable remission. the investigators primary aim is to show that a 3-hour stay at high altitude can alter disease activity of IBD. Ten healthy volunteers, 11 Crohn's disease (CD) patients and 9 ulcerative colitis (UC) patients underwent a 3-hour exposure to hypoxic conditions simulating an altitude of 4,000 m.a.s.l. in a hypobaric low-pressure chamber situated at the Swiss Aeromedical Center, Dubendorf, Switzerland. Stool samples for the analysis of calprotectin and microbiotal composition, biopsy samples from the rectosigmoid region, and blood samples were repetitively collected and analysed in conjunction with detailed records of clinical symptoms over a subsequent interval of 4 weeks.

Recruitment & Eligibility

Inclusion Criteria

had a diagnosis of Crohn's disease or ulcerative colitis at least 6 months prior to inclusion
gave written consent
were in clinical remission (measured by Harvey Bradshaw Activity Index (HBI) in CD and the partial Mayo Score for UC)

Exclusion Criteria

had contraindications for a sigmoidoscopy
had intercurrent bacterial or viral intestinal disease (by culture or serology)
were pregnant or breast feeding
had a severe concomitant disease which excluded from participating in the study by means of the study physician
were likely to or showed no cooperation for the study procedures
had active infection or systemic antibiotic, antiviral or antifungal treatment 3 weeks before baseline
were suffering from short-bowel syndrome
were receiving parenteral nutrition
had a clinical condition which did not allow a stay at heights of 4,000 m.a.s.l.
were claustrophobic

Arm && Interventions

Group	Intervention	Description
hypobaric pressure chamber	hypobaric pressure chamber	The healthy volunteers and IBD patients will have a 3-hour exposure to hypoxic conditions simulating an altitude of 4,000 meters above sea level (m.a.s.l.) in a hypobaric pressure chamber. Before and after the pressure chamber sigmoidoscopy will be performed. During stay in the pressure chamber repetitive measurements of bladder volume will be performed by sonography.
hypobaric pressure chamber	Sigmoidoscopy	The healthy volunteers and IBD patients will have a 3-hour exposure to hypoxic conditions simulating an altitude of 4,000 meters above sea level (m.a.s.l.) in a hypobaric pressure chamber. Before and after the pressure chamber sigmoidoscopy will be performed. During stay in the pressure chamber repetitive measurements of bladder volume will be performed by sonography.

Primary Outcome Measures

Name	Time	Method
Change of partial Mayo Score	4 weeks	partial Mayo Score for Ulcerative Colitis (UC): To calculate the clinical activity of patients with UC the partial Mayo Score was used. This clinical index includes the stool frequency, the amount of blood in the stool and the physician rating of disease activity. Each category has a point value assigned from 0 to 3 and from the sum of all categories a point value was calculated. Remission is defined as 0-1 points, mild disease 2-4 points, moderate disease 5-6 points and severe disease as 7-9 points.
Change of Harvey Bradshaw Activity Index (HBI)	4 weeks	Harvey Bradshaw Activity Index (HBI) in Crohn's disease (CD): To calculate the clinical activity of patients with CD the Harvey Bradshaw Activity Index (HBI) was used. This index includes general wellbeing, abdominal pain, the number of bowel movements, abdominal resistance and CD associated extraintestinal diseases. Each category has a point value assigned and from the sum of all categories a point value is calculated.

Secondary Outcome Measures

Name	Time	Method
change in levels of hypoxia-inducible factor (HIF)-1	4 weeks
Change in levels of angiotensin and vasopressin in urine	4 weeks
Change in levels of catecholamines (adrenaline and noradrenaline) in blood	4 weeks
Inflammation in sigmoid colon	4 weeks	Assessed by sigmoidoscopy: signs of inflammation: * decreased vascular pattern * ulcers * bleeding
Change in bladder volume	4 weeks	measured by sonography (ml)
Change in pro- and anti-inflammatory cytokins	4 weeks	tumor necrosis factor alpha (TNF-α), tumor necrosis factor (TNF), interleukin-1β (IL-1β), interferon-gamma (IFNg), interleukin-10 (IL-10)