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Pathophysiology of stress-induced visceral hypersensitivity

Stanisor, O.I.

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Citation for published version (APA):Stanisor, O. I. (2014). Pathophysiology of stress-induced visceral hypersensitivity.

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Download date: 14 Jul 2020

Introduction

Cha

pter

HYPOTHESIS

6

Figure 1. Schematic representation of the working hypothesis addressed in the different chapters

(CH) of this thesis. Stress is a major trigger for visceral hypersensitivity because it leads to central and

peripheral release of corticotrophin releasing hormone (CRH). Peripheral CRH induces the release of

mast cell mediators like histamine, that modulate (e.g. via the histamine 1 receptor (H1R) afferent

expressed transient receptor ion channel 1 (TRPV1). Next to TRPV1 mediated afferent activation, mast

cell mediators induce gut barrier dysfunction. The subsequent influx of antigens may explain prolonged

post-stress mast cell dependent visceral hypersensitivity. Finally, we hypothesize that susceptibility to

stress induced visceral hypersensitivity can be transferred across generations via so called ‘soft

inheritance’.

Introduction

7

INTRODUCTION

Irritable bowel syndrome (IBS) is the most common functional gastrointestinal disorder. It affects 10

to 20% of the general population in Western countries and involves chronic abdominal pain or

discomfort and alterations in bowel movements in the absence of an organic explanation.1 Next to

restrictions in daily life it also leads to high medical costs. Despite the prevalence and socioeconomic

impact of IBS the pipeline for novel drugs is limited. One of the main reasons for this lack of therapeutic

possibilities is the poor understanding of mechanisms relevant to this disorder. Nevertheless, enhanced

sensitivity to colon or recto-sigmoid distension can be diagnosed in an approximate 30%-60% of

patients. This so called visceral hypersensitivity is considered a pathophysiological mechanism that

may explain abdominal pain complaints. In patients stress is a known trigger for visceral

hypersensitivity2, 3 and indications are that mast cells may be involved in the occurrence of the post-

stress phenotype.4, 5 However, the exact mechanisms are still poorly understood. Therefore, the aim of

the work described in this thesis was to obtain a better understanding of the stress related

pathophysiology of visceral hypersensitivity. Investigations were carried out in the rat model of

maternal separation. Early life stressors are known to contribute to IBS in adults6, 7 and maternal

separation in rats is often used to mimic such predisposing factor.8 In maternal separated rats, the

adverse early life experience pre-disposes for complaints like visceral hypersensitivity and barrier

dysfunction in adult animals. In contrast to others who reported differences in baseline responsiveness

to distension between nonhandled and maternally-separated rats,9, 10 previously separated Long Evans

rats need an acute stress at adult age to bring out the hypersensitive phenotype.11 Since this feature

mimics observations in IBS patients we used Long Evans rats true out our investigations. The possible

role of mast cells, their mediators and triggers for their activation are an important focus of this thesis

(figure 1).

Because others already indicated that mast cells may be involved in post stress visceral hypersensitivity,

we first set out to confirm these observations in our animal model. These experiments are described in

chapter 2. Next to pre-stress administration of the mast cell stabilizer doxantrazole we investigated the

role of nerve growth factor (NGF) by administering anti-NGF antibodies. NGF was evaluated because,

in addition to histamine, it is one of the mast cell mediators known to modulate transient receptor ion

channel 1 (TRPV1).12 This non-selective ligand-gated cation channel is essential for selective

modalities of pain sensation.13 Investigations by Akbar et al. showed that TRPV1 expression was up

regulated in recto-sigmoid biopsies of IBS patients and that increased expression correlated with the

Chapter 1

8

degree of abdominal pain.14 Therefore, we also used two different TRPV1 antagonists to evaluate the

functional role of TRPV1 in post stress visceral hypersensitivity. In addition, we compared TRPV1

expression levels in DRG neurons of nonhandled and maternal separated rats.

We next focused on the possible role of corticotrophin releasing hormone (CRH). Others already

indicated that central expression of this stress hormone is highly relevant in the occurrence of post-

stress IBS like features in animal models. Later it was shown that stress-induced colonic mast cell

degranulation depends on peripheral CRH.15 Despite these evidences, two large clinical trials with

CRH-receptor antagonists failed.16, 17 In chapter 3 we attempted to clarify these contrasting findings.

In relation with this, most investigations concerning a role for peripheral CRH only evaluated pre-stress

administration of CRH-receptor antagonists. Clearly such results elucidate the role of CRH in an acute

stress setting but extrapolating these data to post stress time points may not be appropriate; continued

post-stress mast cell activation may depend on factors other than CRH. Here, we first evaluated whether

there is such a thing as prolonged post-stress mast cell dependent visceral hypersensitivity in maternally

separated rats. Subsequently, we used the CRH-receptor antagonist α-helical CRF (9-41) to compare

the possible role of CRH in pre- and post-stress intervention protocols.

In a clinical trial with the supposed mast cell stabilizer ketotifen this compound decreased visceral

hypersensitivity and improved intestinal symptoms in IBS patients.18 However, when pre- and post-

therapy rectal biopsies were compared for release of histamine and tryptase, results showed no signs of

ketotifen induced mast cell stabilization. Since ketotifen is also a histamine-1-receptor (H1R)

antagonist, these data suggested that the observed therapeutic effect depended on the blocking of this

receptor. This may open up new possibilities for therapy because a long list of H1R antagonists is

available for use in the treatment of allergic rhinitis and urticaria.19 Importantly, in contrast to ketotifen,

these second generation H1-antihistamines do not cross the blood-brain barrier; they are safe, effective

and well tolerated. Therefore, in chapter 4, we tested 2 of these peripherally restricted H1R-antagonists

(ebastine and fexofenadine) for their capacity to reverse post-stress visceral hypersensitivity.

IBS clusters in families, therefore an important line of international research is directed towards the

identification of relevant genetic factors.20 Although twin-studies confirmed that there is a genetic

component in IBS, they also indicated that environmental factors have equal or perhaps even greater

influence.21-25 Similar conclusions can be drawn from studies showing an increased frequency of IBS

in first degree relatives of IBS patients26-30 genetic and intra-familial environmental factors may both

play a role in the observed familial aggregation. Thus, IBS transfer across generations may largely

depend on environmental factors. This is, however, difficult to establish in the human setting.

Therefore, in chapter 5, we used our animal model to investigate whether susceptibility to stress

Introduction

9

induced visceral hypersensitivity in maternal separated Long Evans rats can be transferred across

generations without further separation protocols and, if so, whether this depends on maternal care.

Finally, the possible role of mast cells in the post stress phenotype of these second generation animals

was investigated by the use of the mast cell stabilizer doxantrazole.

Chapter 1

10

REFERENCE LIST

1. Longstreth GF, Thompson WG, Chey WD, Houghton LA, Mearin F, Spiller RC. Functional

bowel disorders. Gastroenterology 2006;130:1480-1491.

2. Posserud I, Agerforz P, Ekman R, Bjornsson ES, Abrahamsson H, Simren M. Altered visceral

perceptual and neuroendocrine response in patients with irritable bowel syndrome during mental

stress. Gut 2004;53:1102-1108.

3. Posserud I, Syrous A, Lindstrom L, Tack J, Abrahamsson H, Simren M. Altered rectal perception

in irritable bowel syndrome is associated with symptom severity. Gastroenterology

2007;133:1113-1123.

4. Gue M, Del Rio-Lacheze C, Eutamene H, Theodorou V, Fioramonti J, Bueno L. Stress-induced

visceral hypersensitivity to rectal distension in rats: role of CRF and mast cells.

Neurogastroenterol Motil 1997;9:271-279.

5. Santos J, Yang PC, Soderholm JD, Benjamin M, Perdue MH. Role of mast cells in chronic stress

induced colonic epithelial barrier dysfunction in the rat. Gut 2001;48:630-636.

6. Chitkara DK, van Tilburg MA, Blois-Martin N, Whitehead WE. Early life risk factors that

contribute to irritable bowel syndrome in adults: a systematic review. Am J Gastroenterol

2008;103:765-774.

7. Klooker TK, Braak B, Painter RC, de R, Sr., van Elburg RM, Van Den Wijngaard RM, Roseboom

TJ, Boeckxstaens GE. Exposure to severe wartime conditions in early life is associated with an

increased risk of irritable bowel syndrome: a population-based cohort study. Am J Gastroenterol

2009;104:2250-2256.

8. Barreau F, Ferrier L, Fioramonti J, Bueno L. New insights in the etiology and pathophysiology

of irritable bowel syndrome: contribution of neonatal stress models. Pediatr Res 2007;62:240-

245.

9. Barreau F, Cartier C, Ferrier L, Fioramonti J, Bueno L. Nerve growth factor mediates alterations

of colonic sensitivity and mucosal barrier induced by neonatal stress in rats. Gastroenterology

2004;127:524-534.

Introduction

11

10. Coutinho SV, Plotsky PM, Sablad M, Miller JC, Zhou H, Bayati AI, McRoberts JA, Mayer EA.

Neonatal maternal separation alters stress-induced responses to viscerosomatic nociceptive

stimuli in rat. Am J Physiol Gastrointest Liver Physiol 2002;282:G307-G316.

11. Welting O, Van Den Wijngaard RM, De Jonge WJ, Holman R, Boeckxstaens GE. Assessment of

visceral sensitivity using radio telemetry in a rat model of maternal separation.

Neurogastroenterol Motil 2005;17:838-845.

12. Chuang HH, Prescott ED, Kong H, Shields S, Jordt SE, Basbaum AI, Chao MV, Julius D.

Bradykinin and nerve growth factor release the capsaicin receptor from PtdIns(4,5)P2-mediated

inhibition. Nature 2001;411:957-962.

13. Geppetti P, Trevisani M. Activation and sensitisation of the vanilloid receptor: role in

gastrointestinal inflammation and function. Br J Pharmacol 2004;141:1313-1320.

14. Akbar A, Yiangou Y, Facer P, Walters JR, Anand P, Ghosh S. Increased capsaicin receptor

TRPV1-expressing sensory fibres in irritable bowel syndrome and their correlation with

abdominal pain. Gut 2008;57:923-929.

15. Tache Y, Kiank C, Stengel A. A role for corticotropin-releasing factor in functional

gastrointestinal disorders. Curr Gastroenterol Rep 2009;11:270-277.

16. Dukes GE, Mayer EA, Kelleher DL, Hicks KJ, Boardley RL, Alpers DH. A randomised double

blind, placebo controlled, crossover study to evaluate the efficacy and safety of the corticotrophin

releasing factor 1 (CRF1) receptor antagonist GW876008 in IBS patients. Neurogastroenterol

Motil 2009;21(Suppl.).

17. Sweetser S, Camilleri M, Linker Nord SJ, Burton DD, Castenada L, Croop R, Tong G, Dockens

R, Zinsmeister AR. Do corticotropin releasing factor-1 receptors influence colonic transit and

bowel function in women with irritable bowel syndrome? Am J Physiol Gastrointest Liver Physiol

2009;296:G1299-G1306.

18. Klooker TK, Braak B, Koopman KE, Welting O, Wouters MM, van der HS, Schemann M,

Bischoff SC, Van Den Wijngaard RM, Boeckxstaens GE. The mast cell stabiliser ketotifen

decreases visceral hypersensitivity and improves intestinal symptoms in patients with irritable

bowel syndrome. Gut 2010;59:1213-1221.

Chapter 1

12

19. Simons FE, Simons KJ. Histamine and H1-antihistamines: celebrating a century of progress. J

Allergy Clin Immunol 2011;128:1139-1150.

20. Saito YA, Talley NJ. Genetics of irritable bowel syndrome. Am J Gastroenterol 2008;103:2100-

2104.

21. Bengtson MB, Ronning T, Vatn MH, Harris JR. Irritable bowel syndrome in twins: genes and

environment. Gut 2006;55:1754-1759.

22. Lembo A, Zaman M, Jones M, Talley NJ. Influence of genetics on irritable bowel syndrome,

gastro-oesophageal reflux and dyspepsia: a twin study. Aliment Pharmacol Ther 2007;25:1343-

1350.

23. Levy RL, Jones KR, Whitehead WE, Feld SI, Talley NJ, Corey LA. Irritable bowel syndrome in

twins: heredity and social learning both contribute to etiology. Gastroenterology 2001;121:799-

804.

24. Mohammed I, Cherkas LF, Riley SA, Spector TD, Trudgill NJ. Genetic influences in irritable

bowel syndrome: a twin study. Am J Gastroenterol 2005;100:1340-1344.

25. Morris-Yates A, Talley NJ, Boyce PM, Nandurkar S, Andrews G. Evidence of a genetic

contribution to functional bowel disorder. Am J Gastroenterol 1998;93:1311-1317.

26. Kalantar JS, Locke GR, III, Zinsmeister AR, Beighley CM, Talley NJ. Familial aggregation of

irritable bowel syndrome: a prospective study. Gut 2003;52:1703-1707.

27. Kanazawa M, Endo Y, Whitehead WE, Kano M, Hongo M, Fukudo S. Patients and nonconsulters

with irritable bowel syndrome reporting a parental history of bowel problems have more impaired

psychological distress. Dig Dis Sci 2004;49:1046-1053.

28. Saito YA, Zimmerman JM, Harmsen WS, De AM, Locke GR, III, Petersen GM, Talley NJ.

Irritable bowel syndrome aggregates strongly in families: a family-based case-control study.

Neurogastroenterol Motil 2008;20:790-797.

29. Saito YA, Petersen GM, Larson JJ, Atkinson EJ, Fridley BL, De AM, Locke GR, III, Zimmerman

JM, mazar-Elder AE, Talley NJ. Familial aggregation of irritable bowel syndrome: a family case-

control study. Am J Gastroenterol 2010;105:833-841.

Introduction

13

30. Whorwell PJ, McCallum M, Creed FH, Roberts CT. Non-colonic features of irritable bowel

syndrome. Gut 1986;27:37-40.