Intestinal disorders

Inflammatory bowel disease (IBD)
This includes Crohn’s disease and Ulcerative colitis (1). The exact cause of these diseases is unknown. The current view is that these diseases are the result of an exaggerated immune response to micro-organisms in the gut, triggered by a combination of genetic predisposition and environmental factors (2). Interestingly, the identified risk-increasing genes are often involved in the recognition and response to bacteria and the functioning of the gut wall (2). The composition of the microbiome is altered in IBD patients and the absence of certain commensal bacterial species (particularly those that make short chain fatty acids) and the presence of pathogenic species correlate with disease activity (3,4). In addition, unlike healthy subjects, the microbiome composition is not stable over time, even in patients in remission (5). So it seems reasonable to say that in IBD there is something drastically wrong in the interaction between immune system and microbiome. Modification of the microbiome appears to lead to disease emission, as shown by a study using “poo transplantation” (6).

Irritable bowel syndrome (IBS)
This is also called irritable bowel syndrome or spastic bowel. IBS is common in Western countries; between 10% and 20% of the population is affected (7). It is therefore one of the most researched conditions. The exact cause is unknown and several factors have been cited, including impaired brain-gut communication, food hypersensitivity, low-grade inflammation (8), and a disrupted microbiome. A strong indication that a disrupted microbiome plays a role is the fact that many cases of disease are preceded by acute intestinal infection by a bacteria, parasite, or sometimes a virus (7,8). Antibiotic use also appears to be a risk factor for the development of IBS. A second indication of a role of the microbiome is various studies have found a reduced diversity and altered composition thereof (9). Sterile laboratory animals colonized with faeces from IBS patients show different gut physiology (such as slower flow and increased pain sensitivity) compared to colonization with faeces from healthy humans (7). A final clue to the role of the microbiome in IBS comes from the observation that influencing the microbiome through probiotics leads to symptom relief in many cases. Although one form of probiotics is not the other (each bacterial species and even strain has different effects) and therefore, care should be taken when lumping clinical studies, several meta-analyzes have been published showing that certain types of probiotics leads to a reduction in complaints in some of the patients (10–12).

Chronic diarrhea
About one in 20 people suffer from this complaint, with about 40% of the cases being elderly (60+) (13). In some of these patients, chronic diarrhea is the result of a condition such as IBD, IBS, or celiac disease, but this is not the case for every patient with chronic diarrhea. Chronic diarrhea can have a variety of causes, and finding the right cause is important for proper treatment (13). Some of these causes, such as infection with parasites, poor digestion, small intestinal bacterial disruption, or food intolerance, are unmistakably related to the microbiome, given its normal function. In patients whose cause of chronic diarrhea is unknown, the composition and distribution of the microbiome in stool samples has been found to differ from healthy participants (14). Moreover, treatment with a probiotic causes little or no change in microbiome properties, nor in complaints or bowel movements in healthy participants, while in patients it leads to clear changes and a decrease in complaints (14). Also in patients for whom the cause of diarrhea is known (e.g. IBD, infection with pathogenic bacteria, or use of antibiotics), active modification of the microbiome by means of probiotics appears to lead to improvements (15), which is a clear indication of the involvement of the disease. microbiome in such cases of chronic diarrhea.

References
1. Clemente JC, Manasson J, Scher JU. The role of the gut microbiome in systemic inflammatory disease. BMJ. 2018; 360: j5145.
2. Matsuoka K, Kanai T. The gut microbiota and inflammatory bowel disease. Semin Immunopathol. 2015; 37: 47–55.
3. Machiels K, Joossens M, Sabino J, Preter VD, Arijs I, Eeckhaut V, Ballet V, Claes K, Immerseel FV, Verbeke K, et al. A decrease of the butyrate-producing species Roseburia hominis and Faecalibacterium prausnitzii defines dysbiosis in patients with ulcerative colitis. Gut. 2014; 63: 1275–83.
4. Forbes JD, Van Domselaar G, Bernstein CN. The Gut Microbiota in Immune-Mediated Inflammatory Diseases. Front Microbiol [Internet]. 2016 [cited 2018 Jan 14]; 7. Available from: https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4939298/
5. Martinez C, Antolin M, Santos J, Torrejon A, Casellas F, Borruel N, Guarner F, Malagelada JR. Unstable Composition of the Fecal Microbiota in Ulcerative Colitis During Clinical Remission. Am J Gastroenterol. 2008; 103: 643.
6. Moayyedi P, Surette MG, Kim PT, Libertucci J, Wolfe M, Onischi C, Armstrong D, Marshall JK, Kassam Z, Reinisch W, et al. Fecal Microbiota Transplantation Induces Remission in Patients With Active Ulcerative Colitis in a Randomized Controlled Trial. Gastroenterology. 2015; 149: 102-109.e6.
7. Ringel Y, Ringel-Kulka T. The Intestinal Microbiota and Irritable Bowel Syndrome. J Clin Gastroenterol. 2015; 49 Suppl 1: S56-59.
8. Ohman L, Simrén M. Intestinal microbiota and its role in irritable bowel syndrome (IBS). Curr Gastroenterol Rep. 2013; 15: 323.
9. Hong SN, Rhee P-L. Unraveling the ties between irritable bowel syndrome and intestinal microbiota. World J Gastroenterol WJG. 2014; 20: 2470–81.
10. Didari T, Mozaffari S, Nikfar S, Abdollahi M. Effectiveness of probiotics in irritable bowel syndrome: Updated systematic review with meta-analysis. World J Gastroenterol WJG. 2015; 21: 3072–84.
11. Ortiz-Lucas M, Tobías A, Saz P, Sebastián JJ. Effect of probiotic species on irritable bowel syndrome symptoms: A bring up to date meta-analysis. Rev Espanola Enfermedades Dig Organo Or Soc Espanola Patol Dig. 2013; 105: 19–36.
12. Moayyedi P, Ford AC, Talley NJ, Cremonini F, Foxx-Orenstein AE, Brandt LJ, Quigley EMM. The efficacy of probiotics in the treatment of irritable bowel syndrome: a systematic review. Gut. 2010; 59: 325–32.
13. Fernández-Bañares F, Accarino A, Balboa A, Domènech E, Esteve M, Garcia-Planella E, Guardiola J, Molero X, Rodríguez-Luna A, Ruiz-Cerulla A, et al. Chronic diarrhea: Definition, classification and diagnosis. Gastroenterol Hepatol Engl Ed. 2016; 39: 535–59.
14. Swidsinski A, Loening – Baucke V, Verstraelen H, Osowska S, Doerffel Y. Biostructure of Fecal Microbiota in Healthy Subjects and Patients With Chronic Idiopathic Diarrhea. Gastroenterology. 2008; 135: 568-579.e2.
15. Scaldaferri F, Pizzoferrato M, Pecere S, Forte F, Gasbarrini A. Bacterial Flora as a Cause or Treatment of Chronic Diarrhea. Gastroenterol Clin North Am. 2012; 41: 581–602.