Microbial Imbalance and IBS Symptoms

Many symptoms of IBS are now being connected to microbial imbalance and its impact on gut physiology.

Altered Fermentation

Increased bacterial fermentation of poorly absorbable carbohydrates resulting from alterations in gut microbial composition contributes to the production of excessive intestinal gases. These gases can cause bloating, flatulence, abdominal pain, and distension.4-7 Additionally, increased production of methane gas has been associated with constipation in IBS-C and increased production of hydrogen gas has been associated with diarrhea in IBS-D.7

Altered GI Motility

The gut microbiota play a critical role in regulating serotonin (5-HT) levels in the colon and systemic circulation.20 Changes in microbial composition can increase the production of both short-chain fatty acids and 5-HT.1,6,7,20 The resulting colonic contraction, increased motility, accelerated intestinal transit, and changes in water and electrolyte transport contribute to the development of diarrhea.1,6,7 Certain intestinal bacteria can also suppress intestinal motility resulting in constipation through the metabolites they produce.21

Visceral Hypersensitivity

Changes in gut microbiota may alter visceral pain perception.8,22 Recent data have shown that gut dysbiosis may cause local or systemic immune activation, which can contribute to visceral hypersensitivity by disrupting epithelial barrier function.4,22 Altered fermentation due to microbial imbalance and gut bacteria modulation of intestinal sensory nerve endings may also contribute to visceral hypersensitivity.22 Studies have shown visceral hypersensitivity development in rats after receiving a fecal transplant from patients with IBS.23

Altered Barrier Function and Immune System Activation

Microbial imbalance can contribute to increased intestinal permeability and immune system activation.1,4,23,24 These changes may lead to inflammatory cell infiltration and the release of cytokines or chemokines that interact with the intestinal environment to cause abdominal pain and diarrhea.1,4,25

Disrupted Signaling Along the Gut-Brain Axis

Dysregulation of the gut-brain axis may contribute to IBS symptoms.1,22 The microbiome-gut-brain axis enables bidirectional communication between the gut microbiota, enteric nervous system, and central nervous system. These neural pathways connect cognitive and emotional activity with peripheral intestinal functions.1,23,26

Changes in cognition and behavior have been observed as a result of disrupted communication between the gut and brain due to dysbiosis.1,20,23,27 According to animal studies, this disruption is caused by the release of inflammatory mediators and neuroactive substances into the systemic circulation. Psychological stress is thought to further influence mucosal immunity, gut microbiota, and gut barrier function, which may perpetuate symptoms similar to those experienced by patients with IBS.20,27,28

disrupted gut-brain axis signaling changes thoughts, behavior, pain perception, psychological stress, mental illness

Adapted, with permission, from: Quigley EMM. The gut-brain axis and the microbiome: clues to pathophysiology and opportunities for novel management strategies in irritable bowel syndrome (IBS). J Clin Med. 2018;7(1):1-8. doi:10.3390/jcm7010006.

 
 
TARGETING GUT MICROBIOTA IN IBS >>
IBS = irritable bowel syndrome.
GI = gastrointestinal.

References

  1. Ringel Y. The gut microbiome in irritable bowel syndrome and other functional bowel disorders. Gastroenterol Clin North Am. 2017;46(1):91-101.
  2. Klem F, Wadhwa A, Prokop LJ, et al. Prevalence, risk factors, and outcomes of irritable bowel syndrome after infectious enteritis: a systematic review and meta-analysis. Gastroenterology. 2017;152(5):1042-1054.
  3. DuPont HL. Review article: evidence for the role of gut microbiota in irritable bowel syndrome and its potential influence on therapeutic targets. Aliment Pharmacol Ther. 2014;39(10):1033-1042.
  4. Lee KN, Lee OY. Intestinal microbiota in pathophysiology and management of irritable bowel syndrome. World J Gastroenterol. 2014;20(27):8886-8897.
  5. Zhuang X, Xiong L, Li L, Li M, Chen M. Alterations of gut microbiota in patients with irritable bowel syndrome: a systematic review and meta-analysis. J Gastroenterol Hepatol. 2017;32(1):28-38.
  6. Passos MDCF, Moraes-Filho JP. Intestinal microbiota in digestive diseases. Arq Gastroenterol. 2017;54(3):255-262.
  7. Ghoshal UC, Shukla R, Ghoshal U, Gwee KA, Ng SC, Quigley EM. The gut microbiota and irritable bowel syndrome: friend or foe? Int J Inflam. 2012;2012:151085.
  8. Stern EK, Brenner DM. Gut microbiota-based therapies for irritable bowel syndrome. Clin Transl Gastroenterol. 2018;9(2):e-134.
  9. Posserud I, Stotzer PO, Björnsson ES, Abrahamsson H, Simrén M. Small intestinal bacterial overgrowth in patients with irritable bowel syndrome. Gut. 2007;56(6):802-808.
  10. Giamarellos-Bouboulis E, Tang J, Pyleris E, et al. Molecular assessment of differences in duodenal microbiome in subjects with irritable bowel syndrome. Scand J Gastroenterol. 2015;50(9):1076-1087.
  11. Pimentel M, Morales W, Pokkunuri V et al. Autoimmunity links vinculin to the pathophysiology of chronic functional bowel changes following campylobacter jejuni infection in a rat model. Dig Dis Sci. 2015;60:1195-1205.
  12. Menees S, Chey W. The gut microbiome and irritable bowel syndrome. F1000Res. 2018;7(F1000 Faculty Rev):1029.
  13. Harris LA, Baffy N. Modulation of the gut microbiota: a focus on treatments for irritable bowel syndrome. Postgrad Med. 2017;129(8):872-888.
  14. Kassinen A, Krogius-Kurikka L, Mäkivuokko H, et al. The fecal microbiota of irritable bowel syndrome patients differs significantly from that of healthy subjects. Gastroenterology. 2007;133(1):24-33.
  15. Carroll IM, Ringel-Kulka T, Keku TO, et al. Molecular analysis of the luminal- and mucosal-associated intestinal microbiota in diarrhea-predominant irritable bowel syndrome. Am J Physiol Gastrointest Liver Physiol. 2011;301(5):G799-G807.
  16. Carroll IM, Ringel-Kulka T, Siddle JP, Ringel Y. Alterations in composition and diversity of the intestinal microbiota in patients with diarrhea-predominant irritable bowel syndrome. Neurogastroenterol Motil. 2012;24(6):521-530.
  17. Tap J, Derrien M, Törnblom H, et al. Identification of an intestinal microbiota signature associated with severity of irritable bowel syndrome. Gastroenterology. 2017;152(1):111-123.
  18. Pyleris E, Giamarellos-Bourboulis EJ, Tzivras D, Koussoulas V, Barbatzas C, Pimentel M. The prevalence of overgrowth by aerobic bacteria in the small intestine by small bowel culture: relationship with irritable bowel syndrome. Dig Dis Sci. 2012;57(5):1321-1329.
  19. König J, Brummer RJ. Alteration of the intestinal microbiota as a cause of and a potential therapeutic option in irritable bowel syndrome. Benef Microbes. 2014;5(3):247-261.
  20. Raskov H, Burcharth J, Pommergaard HC, Rosenberg J. Irritable bowel syndrome, the microbiota and the gut-brain axis. Gut Microbes. 2016;7(5):365-383.
  21. Ohkusa T, Koldo S, Nishikawa Y, Sato N. Gut microbiota and chronic constipation: A review and update. Front Med. 2019;6(19): doi: 10.3389/fmed.2019.00019.
  22. Distrutti E, Monaldi L, Ricci P, Fiorucci S. Gut microbiota role in irritable bowel syndrome: new therapeutic strategies. World J Gastroenterol. 2016;22(7):2219-2241.
  23. Kennedy PJ, Cryan JF, Dinan TG, Clarke G. Irritable bowel syndrome: a microbiome-gut-brain axis disorder? World J Gastroenterol. 2014;20(39):14105-14125.
  24. Quigley EMM. Gut bacteria in health and disease. Gastroenterol Hepatol. 2013;9(9):560-569.
  25. Fan WT, Ding C, Xu NN, Zong S, Ma P, Gu B. Close association between intestinal microbiota and irritable bowel syndrome. Eur J Clin Microbiol Infect Dis. 2017;36(12):2303-2317.
  26. Mayer EA, Tillisch K, Gupta A. Gut/brain axis and the microbiota. J Clin Invest. 2015;125(3):926-938.
  27. Quigley EMM. The gut-brain axis and the microbiome: clues to pathophysiology and opportunities for novel management strategies in irritable bowel syndrome (IBS). J Clin Med. 2018;7(1). doi:10.3390/jcm7010006.
  28. Skonieczna-Zydecka K, Marlicz W, Misera A, Koulaouzidis A, Loniewski I. Microbiome – the missing link in the gut-brain axis: focus on its role in gastrointestinal and mental health. J Clin Med. 2018;7(12). doi:10.3390/jcm7120521.
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