Irritable bowel syndrome pathophysiology: Difference between revisions

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__NOTOC__
{{Irritable bowel syndrome}}
{{CMG}}; {{AE}} {{Cherry}}
==Overview==
[[Irritable bowel syndrome|Irritable Bowel Syndrome]] is caused by a complex interaction of various factors such as intrinsic [[Gastrointestinal tract|gastrointestinal]] factors, [[CNS]] dysregulation and [[psychosocial]] factors, genetic, and environmental factors. Intrinsic gastrointestinal factors include [[Motor skill|motor]] abnormalities, [[Viscus|visceral]] [[hypersensitivity]], [[Immunity (medical)|immune]] activation, [[Mucous membrane|mucosal]] inflammation, altered [[Gut flora|gut microbiota]], and abnormal [[serotonin]] pathways. [[Viscus|Visceral]] [[hypersensitivity]] refers to a decreased threshold for the perception of [[Viscus|visceral]] stimuli that affects [[Spinal cord|spinal]] excitability, [[brain stem]] and [[Cortical area|cortical]] modulation, activation of specific [[Gastrointestinal tract|gastrointestinal]] mediators, and recruitment of peripheral silent [[Nociceptor|nociceptors]]. [[Immunity (medical)|Immune]] activation and [[Mucous membrane|mucosal]] inflammation involves an interaction of [[Lymphocyte|lymphocytes]], [[Mast cell|mast cells]], and [[Cytokines|proinflammatory cytokines]]. Environmental factors encompass dietary changes and [[Infection|infections]]. [[Psychosocial]] factors such as [[Stress (medicine)|stress]], [[anxiety]], and [[depression]] directly shape adult connectivity in the executive control network consisting of structures such as the [[Insular cortex|insula]], anterior [[cingulate cortex]], and the [[thalamus]]. Semipermanent or permanent changes in complex [[Nervous system|neural]] circuits lead to central pain amplification contributing to [[abdominal pain]] in [[Irritable bowel syndrome|IBS]] patients. The dorsolateral [[prefrontal cortex]] activity (responsible for vigilance and alertness of the human brain) and the mid-[[Cingulate cortex|cingulate corte]]<nowiki/>x (engaged in attention pathways and responses) is reduced in [[Irritable bowel syndrome|IBS]] patients. This reduction may lead to alterations in the subjective sensations of pain. Genetic factors also play a role in [[Irritable bowel syndrome|IBS]]. IBS has a high twin [[Concordance (genetics)|concordance]] and familial aggregation. IBS is associated with [[single nucleotide polymorphisms]] ([[Single nucleotide polymorphism|SNPs]]) in genes involved in [[Immunity (medical)|immune]] activation, [[neuropeptide]] hormone function, [[oxidative stress]], [[Pain and nociception|nociception]], [[permeability]] of the GI tract, host-[[Microbiome|microbiota]] interaction, inflammation, and [[Tumor necrosis factors|TNF]] activity.
==Pathophysiology==
==Pathophysiology==


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* IBS is a [[brain]] [[Gastrointestinal tract|gut]] disorder as [[Rectum|rectal]] distension in patients causes increased engagement of regions of the [[brain]] associated with attentional and [[Behavior|behavioral]] responses.<ref name="pmid22108191">{{cite journal |vauthors=Larsson MB, Tillisch K, Craig AD, Engström M, Labus J, Naliboff B, Lundberg P, Ström M, Mayer EA, Walter SA |title=Brain responses to visceral stimuli reflect visceral sensitivity thresholds in patients with irritable bowel syndrome |journal=Gastroenterology |volume=142 |issue=3 |pages=463–472.e3 |year=2012 |pmid=22108191 |pmc=3288538 |doi=10.1053/j.gastro.2011.11.022 |url=}}</ref><ref name="pmid20600024">{{cite journal |vauthors=Elsenbruch S, Rosenberger C, Bingel U, Forsting M, Schedlowski M, Gizewski ER |title=Patients with irritable bowel syndrome have altered emotional modulation of neural responses to visceral stimuli |journal=Gastroenterology |volume=139 |issue=4 |pages=1310–9 |year=2010 |pmid=20600024 |doi=10.1053/j.gastro.2010.06.054 |url=}}</ref><ref name="pmid19651629">{{cite journal |vauthors=Elsenbruch S, Rosenberger C, Enck P, Forsting M, Schedlowski M, Gizewski ER |title=Affective disturbances modulate the neural processing of visceral pain stimuli in irritable bowel syndrome: an fMRI study |journal=Gut |volume=59 |issue=4 |pages=489–95 |year=2010 |pmid=19651629 |doi=10.1136/gut.2008.175000 |url=}}</ref>
* IBS is a [[brain]] [[Gastrointestinal tract|gut]] disorder as [[Rectum|rectal]] distension in patients causes increased engagement of regions of the [[brain]] associated with attentional and [[Behavior|behavioral]] responses.<ref name="pmid22108191">{{cite journal |vauthors=Larsson MB, Tillisch K, Craig AD, Engström M, Labus J, Naliboff B, Lundberg P, Ström M, Mayer EA, Walter SA |title=Brain responses to visceral stimuli reflect visceral sensitivity thresholds in patients with irritable bowel syndrome |journal=Gastroenterology |volume=142 |issue=3 |pages=463–472.e3 |year=2012 |pmid=22108191 |pmc=3288538 |doi=10.1053/j.gastro.2011.11.022 |url=}}</ref><ref name="pmid20600024">{{cite journal |vauthors=Elsenbruch S, Rosenberger C, Bingel U, Forsting M, Schedlowski M, Gizewski ER |title=Patients with irritable bowel syndrome have altered emotional modulation of neural responses to visceral stimuli |journal=Gastroenterology |volume=139 |issue=4 |pages=1310–9 |year=2010 |pmid=20600024 |doi=10.1053/j.gastro.2010.06.054 |url=}}</ref><ref name="pmid19651629">{{cite journal |vauthors=Elsenbruch S, Rosenberger C, Enck P, Forsting M, Schedlowski M, Gizewski ER |title=Affective disturbances modulate the neural processing of visceral pain stimuli in irritable bowel syndrome: an fMRI study |journal=Gut |volume=59 |issue=4 |pages=489–95 |year=2010 |pmid=19651629 |doi=10.1136/gut.2008.175000 |url=}}</ref>
* [[Stress (medicine)|Psychological stress]] also impacts the release of gut [[Inflammation|proinflammatory]] [[Cytokine|cytokines]], contributing to pain in [[Irritable bowel syndrome|IBS]] patients.<ref name="pmid19997094" />
* [[Stress (medicine)|Psychological stress]] also impacts the release of gut [[Inflammation|proinflammatory]] [[Cytokine|cytokines]], contributing to pain in [[Irritable bowel syndrome|IBS]] patients.<ref name="pmid19997094" />
==Genetic factors==
*IBS has high '''[[twin]] [[Concordance (genetics)|concordance]] and [[Family|familial]] [[aggregation]]''':<ref name="pmid11606493">{{cite journal |vauthors=Levy RL, Jones KR, Whitehead WE, Feld SI, Talley NJ, Corey LA |title=Irritable bowel syndrome in twins: heredity and social learning both contribute to etiology |journal=Gastroenterology |volume=121 |issue=4 |pages=799–804 |year=2001 |pmid=11606493 |doi= |url=}}</ref><ref name="pmid9707057">{{cite journal |vauthors=Morris-Yates A, Talley NJ, Boyce PM, Nandurkar S, Andrews G |title=Evidence of a genetic contribution to functional bowel disorder |journal=Am. J. Gastroenterol. |volume=93 |issue=8 |pages=1311–7 |year=1998 |pmid=9707057 |doi=10.1111/j.1572-0241.1998.440_j.x |url=}}</ref><ref name="pmid17509102">{{cite journal |vauthors=Lembo A, Zaman M, Jones M, Talley NJ |title=Influence of genetics on irritable bowel syndrome, gastro-oesophageal reflux and dyspepsia: a twin study |journal=Aliment. Pharmacol. Ther. |volume=25 |issue=11 |pages=1343–50 |year=2007 |pmid=17509102 |doi=10.1111/j.1365-2036.2007.03326.x |url=}}</ref><ref name="pmid16271334">{{cite journal |vauthors=Saito YA, Petersen GM, Locke GR, Talley NJ |title=The genetics of irritable bowel syndrome |journal=Clin. Gastroenterol. Hepatol. |volume=3 |issue=11 |pages=1057–65 |year=2005 |pmid=16271334 |doi= |url=}}</ref><ref name="pmid24041540">{{cite journal |vauthors=Wouters MM, Lambrechts D, Knapp M, Cleynen I, Whorwell P, Agréus L, Dlugosz A, Schmidt PT, Halfvarson J, Simrén M, Ohlsson B, Karling P, Van Wanrooy S, Mondelaers S, Vermeire S, Lindberg G, Spiller R, Dukes G, D'Amato M, Boeckxstaens G |title=Genetic variants in CDC42 and NXPH1 as susceptibility factors for constipation and diarrhoea predominant irritable bowel syndrome |journal=Gut |volume=63 |issue=7 |pages=1103–11 |year=2014 |pmid=24041540 |doi=10.1136/gutjnl-2013-304570 |url=}}</ref><ref name="pmid20234344">{{cite journal |vauthors=Saito YA, Petersen GM, Larson JJ, Atkinson EJ, Fridley BL, de Andrade M, Locke GR, Zimmerman JM, Almazar-Elder AE, Talley NJ |title=Familial aggregation of irritable bowel syndrome: a family case-control study |journal=Am. J. Gastroenterol. |volume=105 |issue=4 |pages=833–41 |year=2010 |pmid=20234344 |pmc=2875200 |doi=10.1038/ajg.2010.116 |url=}}</ref>
**IBS has higher [[Concordance (genetics)|concordance]] in [[Twin|monozygotic]] as compared to [[Twin|dizygotic]] twins.<ref name="pmid11606493" /><ref name="pmid9707057" /><ref name="pmid17509102" /><ref name="pmid17008364">{{cite journal |vauthors=Bengtson MB, Rønning T, Vatn MH, Harris JR |title=Irritable bowel syndrome in twins: genes and environment |journal=Gut |volume=55 |issue=12 |pages=1754–9 |year=2006 |pmid=17008364 |pmc=1856463 |doi=10.1136/gut.2006.097287 |url=}}</ref>
**Individuals with a biologic relative with [[Irritable bowel syndrome|IBS]] have two times a higher risk of developing [[Irritable bowel syndrome|IBS]]. <ref name="pmid10994826">{{cite journal |vauthors=Locke GR, Zinsmeister AR, Talley NJ, Fett SL, Melton LJ |title=Familial association in adults with functional gastrointestinal disorders |journal=Mayo Clin. Proc. |volume=75 |issue=9 |pages=907–12 |year=2000 |pmid=10994826 |doi=10.4065/75.9.907 |url=}}</ref>
*'''[[Single nucleotide polymorphism|Single nucleotide polymorphisms (SNPs)]] in genes:'''
**IBS has [[Single nucleotide polymorphism|SNPs]] in genes playing an important role in host-[[Microbiome|microbiota]] interaction ([[Toll-like receptor|TLR9]], [[Interleukin 6|IL-6]] and [[CDH11|CDH1]]), [[Immunity (medical)|immune]] activation and [[Epithelium|epithelial]] barriers. 
**[[Single nucleotide polymorphism|SNPs]] cause [[inflammation]] and increased [[permeability]] of the [[Gastrointestinal tract|GI tract]], leading to [[Abdominal pain|abdominal discomfort]] and increased [[motility]].<ref name="pmid20044998">{{cite journal |vauthors=Villani AC, Lemire M, Thabane M, Belisle A, Geneau G, Garg AX, Clark WF, Moayyedi P, Collins SM, Franchimont D, Marshall JK |title=Genetic risk factors for post-infectious irritable bowel syndrome following a waterborne outbreak of gastroenteritis |journal=Gastroenterology |volume=138 |issue=4 |pages=1502–13 |year=2010 |pmid=20044998 |doi=10.1053/j.gastro.2009.12.049 |url=}}</ref><ref name="pmid12477767">{{cite journal |vauthors=Gonsalkorale WM, Perrey C, Pravica V, Whorwell PJ, Hutchinson IV |title=Interleukin 10 genotypes in irritable bowel syndrome: evidence for an inflammatory component? |journal=Gut |volume=52 |issue=1 |pages=91–3 |year=2003 |pmid=12477767 |pmc=1773523 |doi= |url=}}</ref>
**Mutation of type V (alpha [[Protein subunit|subunit]]) of ''SCN5A''-encoded [[Voltage-gated ion channel|voltage gated]] [[sodium channel]] causes [[Irritable bowel syndrome|IBS]].<ref name="pmid16771953">{{cite journal |vauthors=Locke GR, Ackerman MJ, Zinsmeister AR, Thapa P, Farrugia G |title=Gastrointestinal symptoms in families of patients with an SCN5A-encoded cardiac channelopathy: evidence of an intestinal channelopathy |journal=Am. J. Gastroenterol. |volume=101 |issue=6 |pages=1299–304 |year=2006 |pmid=16771953 |doi=10.1111/j.1572-0241.2006.00507.x |url=}}</ref><ref name="pmid19056759">{{cite journal |vauthors=Saito YA, Strege PR, Tester DJ, Locke GR, Talley NJ, Bernard CE, Rae JL, Makielski JC, Ackerman MJ, Farrugia G |title=Sodium channel mutation in irritable bowel syndrome: evidence for an ion channelopathy |journal=Am. J. Physiol. Gastrointest. Liver Physiol. |volume=296 |issue=2 |pages=G211–8 |year=2009 |pmid=19056759 |pmc=2643921 |doi=10.1152/ajpgi.90571.2008 |url=}}</ref>
**[[Genome]] wide [[DNA methylation]] profiling is impaired in [[Irritable bowel syndrome|IBS]] and this involves genes linked to [[neuropeptide]] [[hormone]] function and [[Oxidative stress|oxidative]] stress.<ref name="pmid26670691">{{cite journal |vauthors=Mahurkar S, Polytarchou C, Iliopoulos D, Pothoulakis C, Mayer EA, Chang L |title=Genome-wide DNA methylation profiling of peripheral blood mononuclear cells in irritable bowel syndrome |journal=Neurogastroenterol. Motil. |volume=28 |issue=3 |pages=410–22 |year=2016 |pmid=26670691 |pmc=4760882 |doi=10.1111/nmo.12741 |url=}}</ref>
**IBS causes [[mutation]] in the [[neuropeptide]] S [[Receptor (biochemistry)|receptor]] [[gene]] (NPSR1) involved in [[Pain and nociception|nociception]], [[inflammation]] and [[anxiety]] with [[abdominal pain]].<ref name="pmid19732772">{{cite journal |vauthors=Camilleri M, Carlson P, Zinsmeister AR, McKinzie S, Busciglio I, Burton D, Zucchelli M, D'Amato M |title=Neuropeptide S receptor induces neuropeptide expression and associates with intermediate phenotypes of functional gastrointestinal disorders |journal=Gastroenterology |volume=138 |issue=1 |pages=98–107.e4 |year=2010 |pmid=19732772 |pmc=2813358 |doi=10.1053/j.gastro.2009.08.051 |url=}}</ref> 
**[[Gene|Genes]] involved in the regulation of [[Liver|hepatic]] [[bile acid]] [[Chemical synthesis|synthesis]] such as a functional ''Klothoβ'' [[gene]] are mutated in [[Irritable bowel syndrome|IBS]].<ref name="pmid22610000">{{cite journal |vauthors=Wong BS, Camilleri M, Carlson P, McKinzie S, Busciglio I, Bondar O, Dyer RB, Lamsam J, Zinsmeister AR |title=Increased bile acid biosynthesis is associated with irritable bowel syndrome with diarrhea |journal=Clin. Gastroenterol. Hepatol. |volume=10 |issue=9 |pages=1009–15.e3 |year=2012 |pmid=22610000 |pmc=3565429 |doi=10.1016/j.cgh.2012.05.006 |url=}}</ref><ref name="pmid21396369">{{cite journal |vauthors=Wong BS, Camilleri M, Carlson PJ, Guicciardi ME, Burton D, McKinzie S, Rao AS, Zinsmeister AR, Gores GJ |title=A Klothoβ variant mediates protein stability and associates with colon transit in irritable bowel syndrome with diarrhea |journal=Gastroenterology |volume=140 |issue=7 |pages=1934–42 |year=2011 |pmid=21396369 |pmc=3109206 |doi=10.1053/j.gastro.2011.02.063 |url=}}</ref>
*'''TNF polymorphisms:'''
**[[Single nucleotide polymorphism|SNPs]] in [[Tumour necrosis factor|tumour necrosis factor alpha]] ([[Tumor necrosis factor-alpha|TNFα)]] and genes coding for superfamily member 15 (''TNFSF15'') have proven associations with [[Irritable bowel syndrome|IBS]].<ref name="pmid12477767" /><ref name="pmid22684480">{{cite journal |vauthors=Swan C, Duroudier NP, Campbell E, Zaitoun A, Hastings M, Dukes GE, Cox J, Kelly FM, Wilde J, Lennon MG, Neal KR, Whorwell PJ, Hall IP, Spiller RC |title=Identifying and testing candidate genetic polymorphisms in the irritable bowel syndrome (IBS): association with TNFSF15 and TNFα |journal=Gut |volume=62 |issue=7 |pages=985–94 |year=2013 |pmid=22684480 |doi=10.1136/gutjnl-2011-301213 |url=}}</ref><ref name="pmid21636646">{{cite journal |vauthors=Zucchelli M, Camilleri M, Andreasson AN, Bresso F, Dlugosz A, Halfvarson J, Törkvist L, Schmidt PT, Karling P, Ohlsson B, Duerr RH, Simren M, Lindberg G, Agreus L, Carlson P, Zinsmeister AR, D'Amato M |title=Association of TNFSF15 polymorphism with irritable bowel syndrome |journal=Gut |volume=60 |issue=12 |pages=1671–1677 |year=2011 |pmid=21636646 |pmc=3922294 |doi=10.1136/gut.2011.241877 |url=}}</ref>
**[[Tumor necrosis factors|TNF]] [[polymorphisms]] are also associated with post [[Infection|infectious]] [[Irritable bowel syndrome|IBS]] such as ''rs4263839'' in ''TNFSF15'' and [[Irritable bowel syndrome|IBS]], particularly IBS associated with [[constipation]].<ref name="pmid22684480" /><ref name="pmid21636646" />
==Associated conditions==
Several medical [[comorbidities]] appear with greater frequency in [[Irritable bowel syndrome|IBS]] patients. 
===Headache, Fibromyalgia, and Depression===
[[Irritable bowel syndrome|IBS]] patients may be identified with comorbidities such as [[headache]], [[fibromyalgia]] and [[depression]].<ref>{{cite journal |author=Cole JA, Rothman KJ, Cabral HJ, Zhang Y, Farraye FA |title=Migraine,[[fibromyalgia]], and depression among people with IBS:  a prevalence study |journal=BMC gastroenterology |volume=6 |issue=|pages=26 |year=2006 |pmid=17007634 |doi=10.1186/1471-230X-6-26}}</ref><ref name="pmid16614951">{{cite journal |author=Kurland JE, Coyle WJ, Winkler A, Zable E |title=Prevalence of irritable bowel syndrome and depression in [[fibromyalgia]] |journal=Dig. Dis. Sci. |volume=51 |issue=3 |pages=454-60 |year=2006|pmid=16614951 |doi=10.1007/s10620-006-3154-7}}</ref><ref name="pmid16042909">{{cite journal |author=Frissora CL, Koch KL|title=Symptom overlap and comorbidity of irritable bowel syndrome with other conditions |journal=Current gastroenterology reports|volume=7 |issue=4 |pages=264-71 |year=2005 |pmid=16042909 |doi=}}</ref>
===Inflammatory Bowel Disease===
* [[Irritable bowel syndrome|IBS]] and [[Inflammatory bowel disease|IBD]] are interrelated diseases, as patients with [[Inflammatory bowel disease|IBD]] experience [[Irritable bowel syndrome|IBS]]-like symptoms when their [[Inflammatory bowel disease|IBD]] is in remission.<ref name="SIMREN_2002">{{cite journal |author=Simrén M, Axelsson J, Gillberg R, Abrahamsson H, Svedlund J, Björnsson ES|title=Quality of life in inflammatory bowel disease in remission: the impact of IBS-like symptoms and associated psychological factors |journal=Am. J. Gastroenterol. |volume=97 |issue=2 |pages=389-96 |year=2002 |pmid=11866278 |doi=}}</ref><ref name="MINDERHOUD_2004">{{cite journal |author=Minderhoud IM, Oldenburg B, Wismeijer JA, van Berge Henegouwen GP, Smout AJ|title=IBS-like symptoms in patients with inflammatory bowel disease in remission; relationships with quality of life and coping behavior |journal=Dig. Dis. Sci. |volume=49 |issue=3 |pages=469-74 |year=2004 |pmid=15139501 |doi=}}</ref><ref name="QUIGLEY_2005">{{cite journal |author=Quigley EM |title=Irritable bowel syndrome and inflammatory bowel disease: interrelated diseases? |journal=Chinese journal of digestive diseases |volume=6 |issue=3 |pages=122-32 |year=2005 |pmid=16045602|doi=10.1111/j.1443-9573.2005.00202.x}}</ref>
* [[Irritable bowel syndrome|IBS]] is believed to be a type of low-grade [[inflammatory bowel disease]] as serum markers associated with [[inflammation]] have also been found in patients with [[Irritable bowel syndrome|IBS]] .<ref name="BERCIK_2005">{{cite journal |author=Bercik P, Verdu EF, Collins SM |title=Is irritable bowel syndrome a low-grade inflammatory bowel disease? |journal=Gastroenterol. Clin. North Am. |volume=34 |issue=2 |pages=235-45, vi-vii |year=2005|pmid=15862932 |doi=10.1016/j.gtc.2005.02.007}}</ref>
* [[Irritable bowel syndrome|IBS]] patients are16.3 times more likely to develop [[Inflammatory bowel disease|IBD]].<ref name="GARCIA_2000">{{cite journal |author=García Rodríguez LA, Ruigómez A, Wallander MA, Johansson S, Olbe L |title=Detection of colorectal tumor and inflammatory bowel disease during follow-up of patients with initial diagnosis of irritable bowel syndrome |journal=Scand. J. Gastroenterol. |volume=35 |issue=3 |pages=306-11 |year=2000 |pmid=10766326 |doi=}}</ref> 
===Abdominal Surgery===
* [[Irritable bowel syndrome|IBS]] patients are 87% more likely to undergo [[Abdomen|abdominal]] and [[Pelvis|pelvic]] [[surgery]], and three times more likely to undergo [[gallbladder]] [[surgery]].<ref name="pmid16416174">{{cite journal |author=Cole JA, Yeaw JM, Cutone JA, ''et al'' |title=The incidence of abdominal and pelvic surgery among patients with irritable bowel syndrome |journal=Dig. Dis. Sci. |volume=50 |issue=12 |pages=2268–75 |year=2005 |pmid=16416174|doi=10.1007/s10620-005-3047-1}}</ref> 
* [[Irritable bowel syndrome|IBS]] patients were twice as likely to undergo [[hysterectomy]].<ref name="pmid15188159">{{cite journal |author=Longstreth GF, Yao JF|title=Irritable bowel syndrome and surgery: a multivariable analysis |journal=Gastroenterology |volume=126 |issue=7 |pages=1665–73|year=2004 |pmid=15188159 |doi=}}</ref>
===Endometriosis===
There is a statistically significant link between [[Migraine|migraine headaches]], [[Irritable bowel syndrome|IBS]], and [[endometriosis]].<ref name="pmid17635599">{{cite journal |author=Tietjen GE, Bushnell CD, Herial NA, Utley C, White L, Hafeez F|title=Endometriosis is associated with prevalence of comorbid conditions in migraine |journal=Headache |volume=47 |issue=7|pages=1069-78 |year=2007 |pmid=17635599 |doi=10.1111/j.1526-4610.2007.00784.x}}</ref>
==Gross Pathology==
*On [[Gross examination|gross]] [[pathology]], the [[Gastrointestinal tract|GI tract]] appears normal in [[Irritable bowel syndrome|IBS]].
==Microscopic Pathology==
[[Microscopic]] changes that may be found in [[Irritable bowel syndrome|IBS]] patients are as follows:<ref name="pmid10026328">{{cite journal |vauthors=Gwee KA, Leong YL, Graham C, McKendrick MW, Collins SM, Walters SJ, Underwood JE, Read NW |title=The role of psychological and biological factors in postinfective gut dysfunction |journal=Gut |volume=44 |issue=3 |pages=400–6 |year=1999 |pmid=10026328 |pmc=1727402 |doi= |url=}}</ref><ref name="pmid12454854">{{cite journal |vauthors=Törnblom H, Lindberg G, Nyberg B, Veress B |title=Full-thickness biopsy of the jejunum reveals inflammation and enteric neuropathy in irritable bowel syndrome |journal=Gastroenterology |volume=123 |issue=6 |pages=1972–9 |year=2002 |pmid=12454854 |doi=10.1053/gast.2002.37059 |url=}}</ref><ref name="pmid14988823">{{cite journal |vauthors=Barbara G, Stanghellini V, De Giorgio R, Cremon C, Cottrell GS, Santini D, Pasquinelli G, Morselli-Labate AM, Grady EF, Bunnett NW, Collins SM, Corinaldesi R |title=Activated mast cells in proximity to colonic nerves correlate with abdominal pain in irritable bowel syndrome |journal=Gastroenterology |volume=126 |issue=3 |pages=693–702 |year=2004 |pmid=14988823 |doi= |url=}}</ref><ref name="pmid14724817">{{cite journal |vauthors=Dunlop SP, Jenkins D, Neal KR, Spiller RC |title=Relative importance of enterochromaffin cell hyperplasia, anxiety, and depression in postinfectious IBS |journal=Gastroenterology |volume=125 |issue=6 |pages=1651–9 |year=2003 |pmid=14724817 |doi= |url=}}</ref><ref name="pmid11076879">{{cite journal |vauthors=Spiller RC, Jenkins D, Thornley JP, Hebden JM, Wright T, Skinner M, Neal KR |title=Increased rectal mucosal enteroendocrine cells, T lymphocytes, and increased gut permeability following acute Campylobacter enteritis and in post-dysenteric irritable bowel syndrome |journal=Gut |volume=47 |issue=6 |pages=804–11 |year=2000 |pmid=11076879 |pmc=1728147 |doi= |url=}}</ref><ref name="pmid12873581">{{cite journal |vauthors=Dunlop SP, Jenkins D, Spiller RC |title=Distinctive clinical, psychological, and histological features of postinfective irritable bowel syndrome |journal=Am. J. Gastroenterol. |volume=98 |issue=7 |pages=1578–83 |year=2003 |pmid=12873581 |doi=10.1111/j.1572-0241.2003.07542.x |url=}}</ref><ref name="pmid8359068">{{cite journal |vauthors=Weston AP, Biddle WL, Bhatia PS, Miner PB |title=Terminal ileal mucosal mast cells in irritable bowel syndrome |journal=Dig. Dis. Sci. |volume=38 |issue=9 |pages=1590–5 |year=1993 |pmid=8359068 |doi= |url=}}</ref><ref name="pmid11012945">{{cite journal |vauthors=O'Sullivan M, Clayton N, Breslin NP, Harman I, Bountra C, McLaren A, O'Morain CA |title=Increased mast cells in the irritable bowel syndrome |journal=Neurogastroenterol. Motil. |volume=12 |issue=5 |pages=449–57 |year=2000 |pmid=11012945 |doi= |url=}}</ref><ref name="pmid12692417">{{cite journal |vauthors=Park CH, Joo YE, Choi SK, Rew JS, Kim SJ, Lee MC |title=Activated mast cells infiltrate in close proximity to enteric nerves in diarrhea-predominant irritable bowel syndrome |journal=J. Korean Med. Sci. |volume=18 |issue=2 |pages=204–10 |year=2003 |pmid=12692417 |pmc=3055014 |doi=10.3346/jkms.2003.18.2.204 |url=}}</ref><ref name="pmid15247174">{{cite journal |vauthors=Wang LH, Fang XC, Pan GZ |title=Bacillary dysentery as a causative factor of irritable bowel syndrome and its pathogenesis |journal=Gut |volume=53 |issue=8 |pages=1096–101 |year=2004 |pmid=15247174 |pmc=1774156 |doi=10.1136/gut.2003.021154 |url=}}</ref><ref name="pmid2733385">{{cite journal |vauthors=Salzmann JL, Peltier-Koch F, Bloch F, Petite JP, Camilleri JP |title=Morphometric study of colonic biopsies: a new method of estimating inflammatory diseases |journal=Lab. Invest. |volume=60 |issue=6 |pages=847–51 |year=1989 |pmid=2733385 |doi= |url=}}</ref><ref name="pmid13907162">{{cite journal |vauthors=HIATT RB, KATZ L |title=Mast cells in inflammatory conditions of the gastrointestinal tract |journal=Am. J. Gastroenterol. |volume=37 |issue= |pages=541–5 |year=1962 |pmid=13907162 |doi= |url=}}</ref>
{| class="wikitable"
! align="center" style="background: #4479BA; color: #FFFFFF; " |LOCATION
! align="center" style="background: #4479BA; color: #FFFFFF; " ! |LAYER OF INTESTINE INVOLVED
! align="center" style="background: #4479BA; color: #FFFFFF; " ! |MAST CELLS
! align="center" style="background: #4479BA; color: #FFFFFF; " ! |T LYMPHOCYTES
! align="center" style="background: #4479BA; color: #FFFFFF; " ! |ENTEROCHROMAFFIN CELLS
|-
|[[Rectum]]
|[[Mucous membrane|Mucosa]]
| +++/-
| +/-
| +/-
|-
|[[Terminal ileum]]
|[[Mucous membrane|Mucosa]]
| -
| ++
| -
|-
|[[Cecum]]
|[[Mucous membrane|Mucosa]]
| ++
| -
| -
|-
|[[Colon (anatomy)|Colon]]
|[[Muscularis externa]]
| +/-
| -
| -
|-
|[[Jejunum]]
|[[Myentric]] [[plexus]]
| ++
| -
| -
|}
==References==
{{Reflist|2}}
{{WH}}
{{WS}}
[[Category: (name of the system)]]
<references />

Revision as of 22:09, 27 November 2017

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
 
 
 
 
 
 




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