Irritable bowel syndrome pathophysiology: Difference between revisions

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*****Secondary to activation of  [[Neurotransmitter|neurotransmitters]] such as:  
*****Secondary to activation of  [[Neurotransmitter|neurotransmitters]] such as:  
*****[[NMDA receptor|N-methyl D aspartate (NMDA) receptor]]  
*****[[NMDA receptor|N-methyl D aspartate (NMDA) receptor]]  
*****[[nitric oxide]]   
*****[[Nitric oxide]]   
****'''Activation of specific [[Gastrointestinal tract|gastrointestinal]] mediators''' that lead to [[Afferent nerve|afferent]] [[nerve]] fiber sensitization:
****'''Activation of specific [[Gastrointestinal tract|gastrointestinal]] mediators''' that lead to [[Afferent nerve|afferent]] [[nerve]] fiber sensitization:
*****[[kinins]]   
*****[[Kinins]]   
*****[[serotonin]]   
*****[[Serotonin]]   
****'''Central ([[Brain stem|brainstem]] and [[Cerebral cortex|cortical]]) modulation''' with increased activation of anterior [[cingulate cortex]], [[thalamus]] and [[Insular cortex|insula]].
****'''Central ([[Brain stem|brainstem]] and [[Cerebral cortex|cortical]]) modulation''' with increased activation of anterior [[cingulate cortex]], [[thalamus]] and [[Insular cortex|insula]].
*****These structures are involved in processing of pain.   
*****These structures are involved in processing of pain.   
Line 109: Line 109:
** There is an established relationship between [[Irritable bowel syndrome|IBS]] and [[polymorphisms]] in the gene for [[serotonin]] transport causing alteration in [[Intestine|intestinal]] [[peristalsis]] due to change in the [[serotonin]] reuptake efficacy.<ref name="pmid24060757">{{cite journal |vauthors=Grasberger H, Chang L, Shih W, Presson AP, Sayuk GS, Newberry RD, Karagiannides I, Pothoulakis C, Mayer E, Merchant JL |title=Identification of a functional TPH1 polymorphism associated with irritable bowel syndrome bowel habit subtypes |journal=Am. J. Gastroenterol. |volume=108 |issue=11 |pages=1766–74 |year=2013 |pmid=24060757 |pmc=4067697 |doi=10.1038/ajg.2013.304 |url=}}</ref><ref name="pmid21073637">{{cite journal |vauthors=Jun S, Kohen R, Cain KC, Jarrett ME, Heitkemper MM |title=Associations of tryptophan hydroxylase gene polymorphisms with irritable bowel syndrome |journal=Neurogastroenterol. Motil. |volume=23 |issue=3 |pages=233–9, e116 |year=2011 |pmid=21073637 |pmc=3057463 |doi=10.1111/j.1365-2982.2010.01623.x |url=}}</ref><ref name="pmid15138209">{{cite journal |vauthors=Kim HJ, Camilleri M, Carlson PJ, Cremonini F, Ferber I, Stephens D, McKinzie S, Zinsmeister AR, Urrutia R |title=Association of distinct alpha(2) adrenoceptor and serotonin transporter polymorphisms with constipation and somatic symptoms in functional gastrointestinal disorders |journal=Gut |volume=53 |issue=6 |pages=829–37 |year=2004 |pmid=15138209 |pmc=1774073 |doi= |url=}}</ref><ref name="pmid15361494">{{cite journal |vauthors=Yeo A, Boyd P, Lumsden S, Saunders T, Handley A, Stubbins M, Knaggs A, Asquith S, Taylor I, Bahari B, Crocker N, Rallan R, Varsani S, Montgomery D, Alpers DH, Dukes GE, Purvis I, Hicks GA |title=Association between a functional polymorphism in the serotonin transporter gene and diarrhoea predominant irritable bowel syndrome in women |journal=Gut |volume=53 |issue=10 |pages=1452–8 |year=2004 |pmid=15361494 |pmc=1774243 |doi=10.1136/gut.2003.035451 |url=}}</ref>   
** There is an established relationship between [[Irritable bowel syndrome|IBS]] and [[polymorphisms]] in the gene for [[serotonin]] transport causing alteration in [[Intestine|intestinal]] [[peristalsis]] due to change in the [[serotonin]] reuptake efficacy.<ref name="pmid24060757">{{cite journal |vauthors=Grasberger H, Chang L, Shih W, Presson AP, Sayuk GS, Newberry RD, Karagiannides I, Pothoulakis C, Mayer E, Merchant JL |title=Identification of a functional TPH1 polymorphism associated with irritable bowel syndrome bowel habit subtypes |journal=Am. J. Gastroenterol. |volume=108 |issue=11 |pages=1766–74 |year=2013 |pmid=24060757 |pmc=4067697 |doi=10.1038/ajg.2013.304 |url=}}</ref><ref name="pmid21073637">{{cite journal |vauthors=Jun S, Kohen R, Cain KC, Jarrett ME, Heitkemper MM |title=Associations of tryptophan hydroxylase gene polymorphisms with irritable bowel syndrome |journal=Neurogastroenterol. Motil. |volume=23 |issue=3 |pages=233–9, e116 |year=2011 |pmid=21073637 |pmc=3057463 |doi=10.1111/j.1365-2982.2010.01623.x |url=}}</ref><ref name="pmid15138209">{{cite journal |vauthors=Kim HJ, Camilleri M, Carlson PJ, Cremonini F, Ferber I, Stephens D, McKinzie S, Zinsmeister AR, Urrutia R |title=Association of distinct alpha(2) adrenoceptor and serotonin transporter polymorphisms with constipation and somatic symptoms in functional gastrointestinal disorders |journal=Gut |volume=53 |issue=6 |pages=829–37 |year=2004 |pmid=15138209 |pmc=1774073 |doi= |url=}}</ref><ref name="pmid15361494">{{cite journal |vauthors=Yeo A, Boyd P, Lumsden S, Saunders T, Handley A, Stubbins M, Knaggs A, Asquith S, Taylor I, Bahari B, Crocker N, Rallan R, Varsani S, Montgomery D, Alpers DH, Dukes GE, Purvis I, Hicks GA |title=Association between a functional polymorphism in the serotonin transporter gene and diarrhoea predominant irritable bowel syndrome in women |journal=Gut |volume=53 |issue=10 |pages=1452–8 |year=2004 |pmid=15361494 |pmc=1774243 |doi=10.1136/gut.2003.035451 |url=}}</ref>   
** Increased [[serotonin]] production contributes to [[postprandial]] symptoms in [[Irritable bowel syndrome|IBS]] patients, hence providing the rationale for the therapeutic efficacy of 5-HT 3 receptor [[Receptor antagonist|antagonists]] and 5-HT 4 receptor [[Agonist|agonists]] on symptoms in [[Irritable bowel syndrome|IBS]] patients.<ref name="pmid17241888">{{cite journal |vauthors=Gershon MD, Tack J |title=The serotonin signaling system: from basic understanding to drug development for functional GI disorders |journal=Gastroenterology |volume=132 |issue=1 |pages=397–414 |year=2007 |pmid=17241888 |doi=10.1053/j.gastro.2006.11.002 |url=}}</ref><ref name="pmid22071696">{{cite journal |vauthors=Camilleri M |title=Pharmacology of the new treatments for lower gastrointestinal motility disorders and irritable bowel syndrome |journal=Clin. Pharmacol. Ther. |volume=91 |issue=1 |pages=44–59 |year=2012 |pmid=22071696 |doi=10.1038/clpt.2011.261 |url=}}</ref>
** Increased [[serotonin]] production contributes to [[postprandial]] symptoms in [[Irritable bowel syndrome|IBS]] patients, hence providing the rationale for the therapeutic efficacy of 5-HT 3 receptor [[Receptor antagonist|antagonists]] and 5-HT 4 receptor [[Agonist|agonists]] on symptoms in [[Irritable bowel syndrome|IBS]] patients.<ref name="pmid17241888">{{cite journal |vauthors=Gershon MD, Tack J |title=The serotonin signaling system: from basic understanding to drug development for functional GI disorders |journal=Gastroenterology |volume=132 |issue=1 |pages=397–414 |year=2007 |pmid=17241888 |doi=10.1053/j.gastro.2006.11.002 |url=}}</ref><ref name="pmid22071696">{{cite journal |vauthors=Camilleri M |title=Pharmacology of the new treatments for lower gastrointestinal motility disorders and irritable bowel syndrome |journal=Clin. Pharmacol. Ther. |volume=91 |issue=1 |pages=44–59 |year=2012 |pmid=22071696 |doi=10.1038/clpt.2011.261 |url=}}</ref>
==='''[[Psychosocial]] factors and [[CNS]] dysregulation'''===
==='''[[Psychosocial]] factors and [[CNS]] dysregulation'''===
* [[Symptom]] exacerbation occurs in [[Irritable bowel syndrome|IBS]] patients with emotional disturbances,[[Stress (medicine)|stress]], [[anxiety]] or [[depression]]. Traumatic experiences before 18 years of age directly shape adult connectivity in the executive control network consisting of structures such as the [[Insular cortex|insula]], anterior [[cingulate cortex]] and the [[thalamus]].  
* [[Symptom]] exacerbation occurs in [[Irritable bowel syndrome|IBS]] patients with emotional disturbances,[[Stress (medicine)|stress]], [[anxiety]] or [[depression]]. Traumatic experiences before 18 years of age directly shape adult connectivity in the executive control network consisting of structures such as the [[Insular cortex|insula]], anterior [[cingulate cortex]] and the [[thalamus]].  

Revision as of 15:06, 3 January 2018

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Editor-In-Chief: C. Michael Gibson, M.S., M.D. [1]; Associate Editor(s)-in-Chief: Sudarshana Datta, MD [2]

Overview

Irritable Bowel Syndrome is caused by a complex interaction of various factors such as intrinsic gastrointestinal factors, CNS dysregulation and psychosocial factors, genetic, and environmental factors. Intrinsic gastrointestinal factors include motor abnormalities, visceral hypersensitivity, immune activation, mucosal inflammation, altered gut microbiota, and abnormal serotonin pathways. Visceral hypersensitivity refers to a decreased threshold for the perception of visceral stimuli that affects spinal excitability, brain stem and cortical modulation, activation of specific gastrointestinal mediators, and recruitment of peripheral silent nociceptors. Immune activation and mucosal inflammation involves an interaction of lymphocytes, mast cells, and proinflammatory cytokines. Environmental factors encompass dietary changes and infections. Psychosocial factors such as stress, anxiety, and depression directly shape adult connectivity in the executive control network consisting of structures such as the insula, anterior cingulate cortex, and the thalamus. Semipermanent or permanent changes in complex neural circuits lead to central pain amplification contributing to abdominal pain in IBS patients. The dorsolateral prefrontal cortex activity (responsible for vigilance and alertness of the human brain) and the mid-cingulate cortex (engaged in attention pathways and responses) is reduced in IBS patients. This reduction may lead to alterations in the subjective sensations of pain. Genetic factors also play a role in IBS. IBS has a high twin concordance and familial aggregation. IBS is associated with single nucleotide polymorphisms (SNPs) in genes involved in immune activation, neuropeptide hormone function, oxidative stress, nociception, permeability of the GI tract, host-microbiota interaction, inflammation, and TNF activity.

Pathophysiology

Pathogenesis

IBS occurs as a result of an interplay between four main factors:


 
 
 
 
 
CNS dysregulation and psychosocial factors
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
Intrinsic gastrointestinal factors:
Motor abnormalities
Visceral hypersensitivity
Immune activation and mucosal inflammation
• Altered gut microbiota
• Abnormal serotonin pathways
 
 
IRRITABLE BOWEL SYNDROME
 
 
 
Genetic factors:
• Twin concordance
• Familial aggregation
Single nucleotide polymorphisms(SNPs)
• TNF polymorphism
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
Environmental factors:
•Diet
•Infections
 
 
 

Environmental factors

Intrinsic gastrointestinal factors


 
 
 
 
 
 
 
 
 
 
 
 
Spinal hyperexcitability
 
Activation of
N-methyl D aspartate (NMDA) receptor
nitric oxide
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
Central (brainstem and cortical) modulation
 
Increased activation of:
• Anterior cingulate cortex
Thalamus
insula
 
 
 
 
 
 
 
 
 
 
 
Visceral hypersensitivity
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
Activation of specific gastrointestinal mediators
 
Kinins and serotonin activation lead to afferent nerve fiber sensitization
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
Recruitment of peripheral silent nociceptors
 
Increased end organ sensitivity due to hormonal or immune activation