Novel insights in the role of peripheral corticotropin-releasing factor and mast cells in stress-induced visceral hypersensitivity

Research Progress of Central and Peripheral Corticotropin-Releasing Hormone in Irritable Bowel Syndrome with Comorbid Dysthymic Disorders

Irritable bowel syndrome (IBS) is considered a stress disorder characterized by psychological and gastrointestinal dysfunction. IBS patients not only suffer from intestinal symptoms such as abdominal pain, diarrhea, or constipation but also, experience dysthymic disorders such as anxiety and depression. Studies have found that corticotropin-releasing hormone plays a key role in IBS with comorbid dysthymic disorders. Next, we will summarize the effects of corticotropin-releasing hormone from the central nervous system and periphery on IBS with comorbid dysthymic disorders and relevant treatments based on published literatures in recent years.

Psychosocial stress-induced intestinal permeability in healthy humans: What is the evidence?

An impaired intestinal barrier function can be detrimental to the host as it may allow the translocation of luminal antigens and toxins into the subepithelial tissue and bloodstream. In turn, this may cause local and systemic immune responses and lead to the development of pathologies. In vitro and animal studies strongly suggest that psychosocial stress is one of the factors that can increase intestinal permeability via mast-cell dependent mechanisms. Remarkably, studies have not been able to yield unequivocal evidence that such relation between stress and intestinal permeability also exists in (healthy) humans. In the current Review, we discuss the mechanisms that are involved in stress-induced intestinal permeability changes and postulate factors that influence these alterations and that may explain the translational difficulties from in vitro and animal to human studies. As human research differs highly from animal research in the extent to which stress can be applied and intestinal permeability can be measured, it remains difficult to draw conclusions about the presence of a relation between stress and intestinal permeability in (healthy) humans. Future studies should bear in mind these difficulties, and more research into in vivo methods to assess intestinal permeability are warranted.

Trypsin may be associated with duodenal eosinophils through the expression of PAR2 in early chronic pancreatitis and functional dyspepsia with pancreatic enzyme abnormalities

BACKGROUND

Early chronic pancreatitis (ECP) has been reported to advance into chronic pancreatitis, it may be critical to differentiate the pathophysiology of ECP and functional dyspepsia (FD) in patients with pancreatic enzyme abnormalities (FD-P). This study aimed to clarify differences in the pathophysiology of ECP and FD-P and to determine whether duodenal inflammatory responses in the two diseases were associated with protease-activated receptor (PAR) 2, as the trypsin receptor.

METHODS

Eighty patients who presented with FD-P and ECP were enrolled. In duodenal specimens, PAR2 mRNA levels were determined using real-time PCR. Using immunostaining, CD68-, GLP-1-, PRG2-, and CCR2-positive cells, tight junction proteins, and PAR 2 were evaluated.

RESULTS

There were no significant differences in clinical symptoms and gastric motility between ECP and FD-P patients. The CD68-positive cells infiltrations and occludin expression levels in the duodenal mucosa of patients with FD-P were significantly (p<0.001 and p = 0.048, respectively) lower than those in patients with ECP. Although serum trypsin levels in ECP and FD-P patents were significantly (p<0.05 and p<0.001, respectively) associated with duodenal eosinophils counts, elevated trypsin levels were not significantly associated with degranulated eosinophils, occludin, claudin-1 and ZO-1 expression levels in the duodenum of either group. PAR2 mRNA levels were increased in the duodenum of patients with ECP and FD-P. PAR2 was localized in the epithelial cells of the duodenal mucosa and the surface of degranulated eosinophils in ECP and FD-P patients.

CONCLUSIONS

Elevated trypsin levels might be partly associated with duodenal inflammatory responses through PAR2-related degranulated eosinophils and the reduction of occludin in patients with ECP and FD-P.

Role of the nuclear receptor subfamily 4a in mast cells in the development of irritable bowel syndrome

The activation of mast cells (MCs) and mediator release are closely related to the pathophysiology of irritable bowel syndrome (IBS). However, the exact underlying mechanisms are still not completely understood. The nuclear receptor subfamily 4a (Nr4a) is a family of orphan nuclear receptors implicated in regulating MC activation, degranulation, cytokine/chemokine synthesis and release. Acute and chronic stress trigger hypothalamic–pituitaryadrenal axis (HPA) activation to induce the release of corticotropin-releasing hormone (CRH), resulting in MC activation and induction of the Nr4a family. Our newest data showed that Nr4a members were specially over-expressed in colonic MCs of the chronic water-avoidance stress (WAS)-induced visceral hyperalgesia mice, suggesting that Nr4a members might be involved in the pathophysiology of visceral hypersensitivity. In this review, we highlight the present knowledge on roles of Nr4a members in the activation of MCs and the pathophysiology of IBS, and discuss signaling pathways that modulate the activation of Nr4a family members. We propose that a better understanding of Nr4a members and their modulators may facilitate the development of more selective and effective therapies to treat IBS patients.

Sex and Gender Differences in Overlap Syndrome of Functional Gastrointestinal Disorder and Effect of Genetic Polymorphisms in South Korea: A Long-term Follow-up Study

BACKGROUND/AIMS

Overlap functional gastrointestinal disorder (FGID) is associated with more severe gastrointestinal symptoms and lower quality of life. The aim of this study is to evaluate clinical features of non-erosive reflux disease (NERD), functional dyspepsia, irritable bowel syndrome, their overlap in terms of sex and gender, and to assess the risk factors, including genetic polymorphisms.

METHODS

A total of 494 FGIDs and 239 controls were prospectively enrolled between 2004 and 2020. FGIDs were diagnosed based on the Rome III criteria and symptoms were evaluated using a questionnaire. Follow-up questionnaires were conducted to determine the change of symptoms during the 75.8-month mean observation period. Risk factors including genetic polymorphisms in neurotransmitter receptor (SLC6A4 5-HTTLPR, GNB3, ADRA2A, CCKAR, and TRPV1) and cytokine (TNFA and IL10) genes.

RESULTS

NERD was more prevalent in men, and functional dyspepsia in women. Overlap FGIDs (n = 239) were more prevalent than nonoverlap FGIDs (n = 255) in women (P = 0.019). Anxiety and depression scores were higher in the overlaps (P = 0.012 and P < 0.001, respectively). Symptoms were more frequent and severe in the overlap FGIDs than in the non-overlaps (P < 0.001). During followup, symptoms progressed more frequently in the overlap FGIDs, especially in patients with the L/S genotype of SLC6A4 5-HTTLPR and anxiety/depression.

CONCLUSIONS

Overlap FGID patients need attention given their association with anxiety/depression and more severe symptoms, especially in women. Genetic polymorphisms also may be associated with certain symptoms of overlap FGIDs.

Sex and Gender Differences in Overlap Syndrome of Functional Gastrointestinal Disorder and Effect of Genetic Polymorphisms in South Korea: A Long-term Follow-up Study

Background/Aims

Overlap functional gastrointestinal disorder (FGID) is associated with more severe gastrointestinal symptoms and lower quality of life. The aim of this study is to evaluate clinical features of non-erosive reflux disease (NERD), functional dyspepsia, irritable bowel syndrome, their overlap in terms of sex and gender, and to assess the risk factors, including genetic polymorphisms.

Methods

A total of 494 FGIDs and 239 controls were prospectively enrolled between 2004 and 2020. FGIDs were diagnosed based on the Rome III criteria and symptoms were evaluated using a questionnaire. Follow-up questionnaires were conducted to determine the change of symptoms during the 75.8-month mean observation period. Risk factors including genetic polymorphisms in neurotransmitter receptor (SLC6A4 5-HTTLPR, GNB3, ADRA2A, CCKAR, and TRPV1) and cytokine (TNFA and IL10) genes.

Results

NERD was more prevalent in men, and functional dyspepsia in women. Overlap FGIDs (n = 239) were more prevalent than non-overlap FGIDs (n = 255) in women (P = 0.019). Anxiety and depression scores were higher in the overlaps (P = 0.012 and P < 0.001, respectively). Symptoms were more frequent and severe in the overlap FGIDs than in the non-overlaps (P < 0.001). During follow-up, symptoms progressed more frequently in the overlap FGIDs, especially in patients with the L/S genotype of SLC6A4 5-HTTLPR and anxiety/depression.

Conclusions

Overlap FGID patients need attention given their association with anxiety/depression and more severe symptoms, especially in women. Genetic polymorphisms also may be associated with certain symptoms of overlap FGIDs.

Corticotropin-releasing factor receptor 1 (CRF-R1) antagonists: Promising agents to prevent visceral hypersensitivity in irritable bowel syndrome

Corticotropin-releasing factor (CRF) is a 41-amino acid polypeptide that coordinates the endocrine system, autonomic nervous system, immune system, and physiological behavior. CRF is a signaling regulator in the neuro-endocrine-immune (NEI) network that mediates visceral hypersensitivity. Rodent models to simulate changes in intestinal motility similar to those reported in the irritable bowel syndrome (IBS), demonstrate that the CRF receptor 1 (CRF-R1) mediates intestinal hypersensitivity under many conditions. However, the translation of preclinical studies into clinical trials has not been successful possibly due to the lack of sufficient understanding of the multiple variants of CRF-R1 and CRF-R1 antagonists. Investigating the sites of action of central and peripheral CRF is critical for accelerating the translation from preclinical to clinical studies.

Present and Future Therapeutic Approaches to Barrier Dysfunction

There is converging and increasing evidence, but also uncertainty, for the role of abnormal intestinal epithelial barrier function in the origin and development of a growing number of human gastrointestinal and extraintestinal inflammatory disorders, and their related complaints. Despite a vast literature addressing factors and mechanisms underlying changes in intestinal permeability in humans, and its connection to the appearance and severity of clinical symptoms, the ultimate link remains to be established in many cases. Accordingly, there are no directives or clinical guidelines related to the therapeutic management of intestinal permeability disorders that allow health professionals involved in the management of these patients to carry out a consensus treatment based on clinical evidence. Instead, there are multiple pseudoscientific approaches and commercial propaganda scattered on the internet that confuse those affected and health professionals and that often lack scientific rigor. Therefore, in this review we aim to shed light on the different therapeutic options, which include, among others, dietary management, nutraceuticals and medical devices, microbiota and drugs, and epigenetic and exosomes-manipulation, through an objective evaluation of the scientific publications in this field. Advances in the knowledge and management of intestinal permeability will sure enable better options of dealing with this group of common disorders to enhance quality of life of those affected.

Functional and Anatomical Characterization of Corticotropin-Releasing Factor Receptor Subtypes of the Rat Spinal Cord Involved in Somatic Pain Relief

Corticotropin-releasing factor (CRF) orchestrates our body’s response to stressful stimuli. Pain is often stressful and counterbalanced by activation of CRF receptors along the nociceptive pathway, although the involvement of the CRF receptor subtypes 1 and/or 2 (CRF-R1 and CRF-R2, respectively) in CRF-induced analgesia remains controversial. Thus, the aim of the present study was to examine CRF-R1 and CRF-R2 expression within the spinal cord of rats with Freund’s complete adjuvant-induced unilateral inflammation of the hind paw using reverse transcriptase polymerase chain reaction, Western blot, radioligand binding, and immunofluorescence confocal analysis. Moreover, the antinociceptive effects of intrathecal (i.t.) CRF were measured by paw pressure algesiometer and their possible antagonism by selective antagonists for CRF-R1 and/or CRF-R2 as well as for opioid receptors. Our results demonstrated a preference for the expression of CRF-R2 over CRF-R1 mRNA, protein, binding sites and immunoreactivity in the dorsal horn of the rat spinal cord. Consistently, CRF as well as CRF-R2 agonists elicited potent dose-dependent antinociceptive effects which were antagonized by the i.t. CRF-R2 selective antagonist K41498, but not by the CRF-R1 selective antagonist NBI35965. In addition, i.t. applied opioid antagonist naloxone dose-dependently abolished the i.t. CRF- as well as CRF-R2 agonist-elicited inhibition of somatic pain. Importantly, double immunofluorescence confocal microscopy of the spinal dorsal horn showed CRF-R2 on enkephalin (ENK)-containing inhibitory interneurons in close opposition of incoming mu-opioid receptor-immunoreactive nociceptive neurons. CRF-R2 was, however, not seen on pre- or on postsynaptic sensory neurons of the spinal cord. Taken together, these findings suggest that i.t. CRF or CRF-R2 agonists inhibit somatic inflammatory pain predominantly through CRF-R2 receptors located on spinal enkephalinergic inhibitory interneurons which finally results in endogenous opioid-mediated pain inhibition.

Effects of stress-related peptides on chloride secretion in the mouse proximal colon

BACKGROUND

Stress increases intestinal secretion and exacerbates symptoms of irritable bowel syndrome (IBS). Peripherally derived corticotropin-releasing factor (CRF) is known to mediate stress-induced intestinal secretion, presumably by activation of CRF₁ receptors in the gut. The present study aimed to ascertain the role of CRF₂ activation in intestinal secretion by three other members of CRF peptide family, urocortin (UCN) 1-3, in wild type (WT) and CRF₂ knockout (Crhr2^-/- ) mice.

METHODS

Mucosal/submucosal preparations from proximal colon of WT and Crhr2^-/- mice of both sexes were mounted in Ussing chambers for measurement of short-circuit current (I_sc ) as an indicator of ion secretion.

KEY RESULTS

Male mice demonstrated a significantly higher baseline I_sc than female in both WT and Crhr2^-/- genotypes. CRF and UCN1-3 (1 μM) caused greater increases in colonic I_sc (ΔI_sc ) in male than female. Colonic I_sc response to the selective CRF₁ agonist, stressin1, was similar in both sexes. In male mice, the selective CRF₂ agonists (UCN2 and UCN3) caused significantly greater ΔI_sc than CRF and stressin1. UCN2- and UCN3-evoked ΔI_SC was significantly reduced in preparations pretreated with the selective CRF₂ antagonist antisauvagine-30 and in Crhr2^-/- mice. The prosecretory effects of urocortins were due to increases in Cl^- secretion and involved enteric neurons and mast cells.

CONCLUSIONS AND INFERENCE

The findings revealed sex differences in baseline colonic secretion and responses to stress-related peptides. CRF₂ receptors play a more prominent role in colonic secretion in male mice. The greater baseline secretion and responses to UCNs may contribute to the higher prevalence of diarrhea-predominant IBS in males.

Psychological Factors Influence the Overlap Syndrome in Functional Gastrointestinal Disorder and Quality of Life among Psychiatric Patients in South Korea

OBJECTIVE

The aim of this study was to investigate the predictor variables that could influence overlap syndrome in functional gastrointestinal disorders (FGID) among psychiatric patients.

METHODS

Data collected from 170 outpatients visiting the psychiatric clinic at a university hospital. FGIDs were screened according to the Rome III questionnaire-Korean version. Demographic factors were investigated, and psychosocial factors were evaluated using the Hospital Anxiety Depression Scale, Patient Health Questionnaire-15, Childhood Trauma Questionnaire-Korean and the Short form health survey. Chi-squared test, Student's t-test, one-way ANOVA, and Pearson's correlation test were used as statistical analysis methods.

RESULTS

There were no differences in the epidemiologic data between the two groups divided according to the FGID status. In those with FGID overlap syndrome, FD-NERD was most common (n=29), followed by IBS-NERD (n=20). Patients with overlap syndrome had the highest depressive, anxiety, and somatic symptoms. The overlap syndrome group had the lowest physical component summary and mental component summary. FGID symptom severity was significantly correlated with PCS and MCS in the overlap syndrome group.

CONCLUSION

Psychological factors are associated with the overlap syndrome of FGID. Acknowledging this common comorbidity may facilitate the recognition and treatment of patients with FGID.

The role of peripheral corticotropin-releasing factor signaling in a rat model of stress-induced gastric hyperalgesia

BACKGROUND

Functional dyspepsia (FD) is a common gastrointestinal disorder associated with persistent or recurrent upper gastrointestinal tract symptoms such as pain without any obvious pathological changes. Psychological and psychiatric factors might have a pathogenic role in FD. Changes in the sensation of stomach pain were determined after application of stress to adult rats. The involvement of corticotropin-releasing factor (CRF), Type 2 CRF receptor (CRF₂) and inflammatory cytokine interleukin-6 (IL-6) was also investigated in the gastric hyperalgesia observed in this model.

RESULTS

Repeated water avoidance stress (WA-S) produced gastric hyperalgesia, with no obvious lesions in the gastric mucosa. Gastric hyperalgesia was inhibited by CRF and CRF₂ antagonists, suggesting their involvement in gastric hyperalgesia observed after application of stress. Gastric hyperalgesia was inhibited by IL-6 neutralizing antibody. Immunofluorescence staining demonstrated CRF, CRF₂, urocortin (Ucn)1, and Ucn2-positive cells in the gastric mucosa. CRF₂-positive cells increased after WA-S, compared to sham stress. CRF₂ and Ucn2 were expressed in the mast cells in the gastric mucosa.

CONCLUSIONS

CRF₂ plays an important role in gastric hyperalgesia produced by stress. CRF₂ signaling may be a useful therapeutic target for functional dyspepsia.

The transcripts of CRF and CRF receptors under fasting stress in Dabry's sturgeon (Acipenser dabryanus Dumeril)

Dabry's sturgeon (Acipenser dabryanus Dumeril, 1868) belongs to Sturgeon and is distributed throughout the mainstream of the upper Yangtze River. While there is little research onphysiological mechanism of Dabry's sturgeon, such as feeding regulation by the CRF system. At present, CRF is thought to regulate feeding via CRF receptors (CRF-Rs) in several mammals, but relatively few studies of CRF and feeding exist in teleosts. Herein, the transcripts of CRF and CRF-Rs under fasting stress in Dabry's sturgeon (Acipenser dabryanus Dumeril) have been explored. A full length Dabry's sturgeon CRF cDNA of 953 bp was identified, which contained a 447 bp open reading frame (ORF). A partial CRF-R1 cDNA of 1053 bp and CRF-R2 cDNA of 906 bp corresponding to the coding sequences (CDS) was obtained. In addition, analysis of the tissue distribution of CRF and CRF-Rs mRNAs revealed they were widely distributed in the central and peripheral nervous systems. Furthermore, periprandial (preprandial and postprandial), fasting, and re-feeding experiments revealed CRF mRNA was significantly increased 1 h and 3 h after feeding and CRF and CRF-Rs transcripts were significantly decreased after 10 days fasting, and significantly increased on re-feeding on day 10. These results suggest that CRF and CRF-Rs might regulate feeding by acting as satiety factors.

Mast Cells in Gut and Brain and Their Potential Role as an Emerging Therapeutic Target for Neural Diseases

The mast cells (MCs) are the leader cells of inflammation. They are well known for their involvement on allergic reactions through degranulation and release of vasoactive, inflammatory, and nociceptive mediators. Upon encountering potential danger signal, MCs are true sensors of the environment, the first to respond in rapid and selective manner. The MC activates the algic response and modulates the evolution of nociceptive pain, typical of acute inflammation, to neuropathic pain, typical not only of chronic inflammation but also of the dysregulation of the pain system. Yet, MC may contribute to modulate intensity of the associated depressive and anxiogenic component on the neuronal and microglial biological front. Chronic inflammation is a common mediator of these co-morbidities. In parallel to the removal of the etiological factors of tissue damage, the modulation of MC hyperactivity and the reduction of the release of inflammatory factors may constitute a new frontier of pharmacological intervention aimed at preventing the chronicity of inflammation, the evolution of pain, and also the worsening of the depression and anxiogenic state associated with it. So, identifying specific molecules able to modify MC activity may be an important therapeutic tool. Various preclinical evidences suggest that the intestinal microbiota contributes substantially to mood and behavioral disorders. In humans, conditions of the microbiota have been linked to stress, anxiety, depression, and pain. MC is likely the crucial neuroimmune connecting between these components. In this review, the involvement of MCs in pain, stress, and depression is reviewed. We focus on the MC as target that may be mediating stress and mood disorders via microbiota-gut-brain axis.

Brain and Gut CRF Signaling: Biological Actions and Role in the Gastrointestinal Tract

BACKGROUND

Corticotropin-releasing factor (CRF) pathways coordinate behavioral, endocrine, autonomic and visceral responses to stress. Convergent anatomical, molecular, pharmacological and functional experimental evidence supports a key role of brain CRF receptor (CRF-R) signaling in stress-related alterations of gastrointestinal functions. These include the inhibition of gastric acid secretion and gastric-small intestinal transit, stimulation of colonic enteric nervous system and secretorymotor function, increase intestinal permeability, and visceral hypersensitivity. Brain sites of CRF actions to alter gut motility encompass the paraventricular nucleus of the hypothalamus, locus coeruleus complex and the dorsal motor nucleus while those modulating visceral pain are localized in the hippocampus and central amygdala. Brain CRF actions are mediated through the autonomic nervous system (decreased gastric vagal and increased sacral parasympathetic and sympathetic activities). The activation of brain CRF-R2 subtype inhibits gastric motor function while CRF-R1 stimulates colonic secretomotor function and induces visceral hypersensitivity. CRF signaling is also located within the gut where CRF-R1 activates colonic myenteric neurons, mucosal cells secreting serotonin, mucus, prostaglandin E2, induces mast cell degranulation, enhances mucosal permeability and propulsive motor functions and induces visceral hyperalgesia in animals and humans. CRF-R1 antagonists prevent CRF- and stressrelated gut alterations in rodents while not influencing basal state.

DISCUSSION

These preclinical studies contrast with the limited clinical positive outcome of CRF-R1 antagonists to alleviate stress-sensitive functional bowel diseases such as irritable bowel syndrome.

CONCLUSION

The translational potential of CRF-R1 antagonists in gut diseases will require additional studies directed to novel anti-CRF therapies and the neurobiology of brain-gut interactions under chronic stress.

Antagonizing the corticotropin releasing hormone receptor 1 with antalarmin reduces the progression of endometriosis

Endometriosis is a disorder in which endometrial tissue is found outside the uterus causing pain, infertility and stress. Finding effective, non-hormonal and long-term treatments for endometriosis still remains one of the most significant challenges in the field. Corticotropin releasing hormone (CRH) is one of the main signaling peptides within the hypothalamic pituitary adrenal (HPA) axis released in response to stress. CRH can affect nervous and visceral tissues such as the uterus and gut via activation of two types of CRH receptors: CRHR1 and CRHR2. Our aim was to determine if blocking CRHR1 with antalarmin will reduce endometriosis progression. In experiment 1 we induced endometriosis in female rats by suturing uterine horn tissue next to the intestinal mesentery and allowed to progress for 7 days. We determined that after 7 days, there was a significant increase in CRHR1 within endometriotic vesicles as compared to normal uterus. In Experiment 2, we induced endometriosis and administered either antalarmin (20 mg/kg, i.p.) or vehicle during the first 7 days after surgery. A separate group of sham surgery rats served as non-endometriosis controls. Endometriosis was allowed to progress until 60 days after surgery, at which time rats were tested for anxiety behaviors. At the time of sacrifice, endometriotic vesicles, uterus and blood were collected. Treatment with antalarmin significantly reduced the size (67% decrease) and number (30% decrease) of endometriotic vesicles. Antalarmin also prevented the increase in CRH and CRHR1 mRNA within endometriotic vesicles but not of glucocorticoid receptor. Endometriosis did not change anxiety behaviors in the open field and zero-maze tests and prior antalarmin administration did not modify this. Our data provides the first in-vivo demonstration for use of CRHR1 antagonist for the treatment of endometriosis opening the possibility for further exploring CRH signaling as a treatment target for this debilitating disease.

Electroacupuncture Relieves Visceral Hypersensitivity by Inactivating Protease-Activated Receptor 2 in a Rat Model of Postinfectious Irritable Bowel Syndrome

Background

The role of protease-activated receptor 2 (PAR2) in the analgesic effect of electroacupuncture (EA) on visceral hypersensitivity (VH) in postinfectious irritable bowel syndrome (PI-IBS) has yet to be elucidated.

Aim

In this study, we investigated the molecular mechanisms underlying the analgesic effect of EA in a rat model of PI-IBS.

Methods

Visceral hypersensitivity was evaluated by the abdominal withdrawal reflex test before and after administration of the PAR2 agonist, PAR2-AP, and/or EA. The protein expression and mRNA levels of PAR2, CGRP, SP, and TPSP in colon tissues were measured by immunofluorescence, western blot, and RT-PCR.

Results

We found that EA could alleviate VH and significantly decrease protein and mRNA levels of PAR2, TPSP, CGRP, and SP in PI-IBS rats. The analgesic effect of EA on VH was slightly reduced in the presence of PAR2-AP.

Conclusions

These results suggest that EA alleviates VH symptoms through downregulation of the levels of the TPSP/PAR2/SP/CGRP signaling axis in colon tissues in PI-IBS rats. Together, our data suggests that PAR2 plays a critical role in the analgesic effect of EA on VH in PI-IBS.

Microstructural changes in the brain in elderly patients with irritable bowel syndrome

OBJECTIVE

It is unclear how alterations in gray matter volume and white matter density affect elderly patients with irritable bowel syndrome (IBS). This study aimed to investigate the relationship between structural changes in the brain and psychological stress in elderly IBS patients.

METHODS

Eighteen IBS patients and 12 healthy controls underwent structural magnetic resonance imaging. Voxel-based morphometry and diffusion tensor imaging analysis were used to identify abnormalities in cortical regions and white matter, respectively.

RESULTS

The IBS group showed a significant GMV reduction in the cingulate gyrus, occipital lobe, hippocampus, frontal lobe, medial frontal gyrus, superior frontal gyrus, and limbic lobe as well as a higher GMV in the insula, superior temporal gyrus, angular gyrus, and supramarginal gyrus. Diffusion tensor imaging indicated that the IBS group had lower fractional anisotropy in the corpus callosum, upper corona, fornix, internal capsule, and brainstem. Additionally, IBS patients showed higher mean diffusivity in the cingulate gyrus, corpus callosum, upper corona, internal capsule, external capsule, fornix, and superior longitudinal fasciculus.

CONCLUSION

Structural changes in the brain play a role in the condition of elderly IBS patients. Psychological stress is an important factor for developing IBS via the hypothalamic-pituitary-adrenal axis.

VIP is involved in peripheral CRF-induced stimulation of propulsive colonic motor function and diarrhea in male rats

We investigated whether vasoactive intestinal peptide (VIP) and/or prostaglandins contribute to peripheral corticotropin-releasing factor (CRF)-induced CRF1 receptor-mediated stimulation of colonic motor function and diarrhea in rats. The VIP antagonist, [4Cl-D-Phe6, Leu17]VIP injected intraperitoneally completely prevented CRF (10 µg/kg ip)-induced fecal output and diarrhea occurring within the first hour after injection, whereas pretreatment with the prostaglandins synthesis inhibitor, indomethacin, had no effect. In submucosal plexus neurons, CRF induced significant c-Fos expression most prominently in the terminal ileum compared with duodenum and jejunum, whereas no c-Fos was observed in the proximal colon. c-Fos expression in ileal submucosa was colocalized in 93.4% of VIP-positive neurons and 31.1% of non-VIP-labeled neurons. CRF1 receptor immunoreactivity was found on the VIP neurons. In myenteric neurons, CRF induced only a few c-Fos-positive neurons in the ileum and a robust expression in the proximal colon (17.5 ± 2.4 vs. 0.4 ± 0.3 cells/ganglion in vehicle). The VIP antagonist prevented intraperitoneal CRF-induced c-Fos induction in the ileal submucosal plexus and proximal colon myenteric plexus. At 60 min after injection, CRF decreased VIP levels in the terminal ileum compared with saline (0.8 ± 0.3 vs. 2.5 ± 0.7 ng/g), whereas VIP mRNA level detected by qPCR was not changed. These data indicate that intraperitoneal CRF activates intestinal submucosal VIP neurons most prominently in the ileum and myenteric neurons in the colon. It also implicates VIP signaling as part of underlying mechanisms driving the acute colonic secretomotor response to a peripheral injection of CRF, whereas prostaglandins do not play a role. NEW & NOTEWORTHY Corticotropin-releasing factor (CRF) in the gut plays a physiological role in the stimulation of lower gut secretomotor function induced by stress. We showed that vasoactive intestinal peptide (VIP)-immunoreactive neurons in the ileal submucosal plexus expressed CRF1 receptor and were prominently activated by CRF, unlike colonic submucosal neurons. VIP antagonist abrogated CRF-induced ileal submucosal and colonic myenteric activation along with functional responses (defecation and diarrhea). These data point to VIP signaling in ileum and colon as downstream effectors of CRF.

Role of mast cell activation and degranulation in irritable bowel syndrome

Irritable bowel syndrome (IBS) is a common functional gastrointestinal disorder whose treatment is unsatisfactory as its pathophysiology is multifactorial. The factors involved in IBS pathophysiology include visceral hypersensitivity, intestinal dysmotility, psychological factors, dysregulated gut-brain axis, intestinal microbiota alterations, impaired intestinal permeability, and mucosal immune alterations. Recently, mucosal immune alterations have received much attention in IBS. Mast cells are abundant in the intestine, and they communicate with adjacent cells such as epithelial, neuronal, smooth muscle cells or other immune cells through the mediators released when they are activated. Many studies have suggested that mast cells play a role in the pathophysiology of IBS. This review will focus on the role of mast cells in IBS.

Chronic early life stress induced by limited bedding and nesting (LBN) material in rodents: critical considerations of methodology, outcomes and translational potential

The immediate and long-term effects of exposure to early life stress (ELS) have been documented in humans and animal models. Even relatively brief periods of stress during the first 10 days of life in rodents can impact later behavioral regulation and the vulnerability to develop adult pathologies, in particular an impairment of cognitive functions and neurogenesis, but also modified social, emotional, and conditioned fear responses. The development of preclinical models of ELS exposure allows the examination of mechanisms and testing of therapeutic approaches that are not possible in humans. Here, we describe limited bedding and nesting (LBN) procedures, with models that produce altered maternal behavior ranging from fragmentation of care to maltreatment of infants. The purpose of this paper is to discuss important issues related to the implementation of this chronic ELS procedure and to describe some of the most prominent endpoints and consequences, focusing on areas of convergence between laboratories. Effects on the hypothalamic-pituitary adrenal (HPA) axis, gut axis and metabolism are presented in addition to changes in cognitive and emotional functions. Interestingly, recent data have suggested a strong sex difference in some of the reported consequences of the LBN paradigm, with females being more resilient in general than males. As both the chronic and intermittent variants of the LBN procedure have profound consequences on the offspring with minimal external intervention from the investigator, this model is advantageous ecologically and has a large translational potential. In addition to the direct effect of ELS on neurodevelopmental outcomes, exposure to adverse early environments can also have intergenerational impacts on mental health and function in subsequent generation offspring. Thus, advancing our understanding of the effect of ELS on brain and behavioral development is of critical concern for the health and wellbeing of both the current population, and for generations to come.

Clinical Characteristics, Comorbidities and Hospital Outcomes in Hospitalizations with Cyclic Vomiting Syndrome: A Nationwide Analysis

BACKGROUND

Data on cyclic vomiting syndrome (CVS) are limited to studies from tertiary care centers. There is a paucity of information about CVS on a national scale.

AIM

To study the clinical characteristics, comorbidities, and hospital outcomes in patients hospitalized with CVS using a nationwide database.

METHODS

We identified all hospitalizations associated with a primary diagnosis of CVS in 2010 and 2011 using the Nationwide Inpatient Sample with an age category of 18-55 years. A 1:2 random sample of non-CVS hospitalizations with the same age category was obtained, and comparisons between groups were made. Multivariate logistic regression analysis was used to determine comorbidities independently associated with CVS.

RESULTS

Our study included 20,952 CVS and 44,262 non-CVS patients. CVS patients tended to be younger, male, and white compared to non-CVS patients. On multivariate analysis, CVS was significantly associated with comorbidities including dysautonomia, migraine, anxiety, marijuana use, irritable bowel syndrome, gastroparesis, gastroesophageal reflux disease, asthma, cigarette smoking, and hypertension. CVS patients underwent esophagogastroduodenoscopy, colonoscopy, and gastric emptying tests more frequently. They had more favorable hospital outcomes like more routine discharges (discharge to home/self-care), lower mortality, and shorter length of stay but tended to leave against medical advice more frequently. CVS patients incurred total hospital charges of about $400 million over the 2 years.

CONCLUSIONS

Our study showed that CVS is associated with several comorbidities and incurred substantial health care costs despite benign outcomes. Efforts to optimize therapy of CVS, manage comorbid conditions and reduce healthcare utilization are warranted.

The effect of intravenous corticotropin-releasing hormone administration on esophageal sensitivity and motility in health

Esophageal hypersensitivity is important in gastroesophageal reflux disease (GERD) patients who are refractory to acid-suppressive therapy. Stress affects visceral sensitivity and exacerbates heartburn in GERD. Peripheral CRH is a key mediator of the gut stress response. We hypothesize that CRH increases esophageal sensitivity and alters esophageal motility in health. Esophageal sensitivity to thermal, mechanical, electrical, and chemical stimuli was assessed in 14 healthy subjects after administration of placebo or CRH (100 μg iv). Perception scores were assessed for first perception, pain perception threshold (PPT), and pain tolerance threshold (PTT). Esophageal motility was investigated by high-resolution impedance manometry, before and after CRH and evaluated by distal contractile integral (DCI) and intrabolus pressure (IBP). Pressure flow analysis assessed bolus clearance (impedance ratio), degree of pressurization needed to propel bolus onward (IBP slope), and pressure flow (pressure flow index, PFI). Stress and mood were assessed during the study. Sensitivity to mechanical distention was increased after CRH compared with placebo (PPT: P = 0.0023; PTT: P = 0.0253). CRH had no influence on the other stimulations. DCI was increased for all boluses (liquid, P = 0.0012; semisolid, P = 0.0017; solid, P = 0.0107). Impedance ratio for liquid (P < 0.0001) and semisolid swallows (P = 0.0327) decreased after CRH. IBP slope increased after CRH for semisolid (P = 0.0041) and solid (P = 0.0003) swallows. PFI increased for semisolid (P = 0.0017) and solid swallows (P = 0.0031). CRH increased esophageal sensitivity to mechanical distention, not to the other stimulation modalities. CRH increased esophageal contractility and tone, decreased LES relaxation, increased esophageal bolus pressurization, improved esophageal bolus clearance, and increased pressure flow.NEW & NOTEWORTHY This is the first study to address the effect of corticotropin-releasing hormone (CRH) on esophageal sensitivity and alterations in motility in health. CRH administration increased esophageal sensitivity to mechanical distention. This effect is accompanied by an increase in esophageal contractility and tone and a decrease in lower esophageal sphincter relaxation. CRH increased esophageal bolus pressurization, improved esophageal bolus clearance, and increased pressure flow. The changes in esophageal contractile properties may underlie the increased sensitivity to mechanical distention after CRH.

Human Intestinal Barrier Function in Health and Disease

The gastrointestinal tract consists of an enormous surface area that is optimized to efficiently absorb nutrients, water, and electrolytes from food. At the same time, it needs to provide a tight barrier against the ingress of harmful substances, and protect against a reaction to omnipresent harmless compounds. A dysfunctional intestinal barrier is associated with various diseases and disorders. In this review, the role of intestinal permeability in common disorders such as infections with intestinal pathogens, inflammatory bowel disease, irritable bowel syndrome, obesity, celiac disease, non-celiac gluten sensitivity, and food allergies will be discussed. In addition, the effect of the frequently prescribed drugs proton pump inhibitors and non-steroidal anti-inflammatory drugs on intestinal permeability, as well as commonly used methods to assess barrier function will be reviewed.

Comparison of Electroacupuncture and Moxibustion for Relieving Visceral Hypersensitivity in Rats with Constipation-Predominant Irritable Bowel Syndrome

Aim. To compare whether there is different effect between electroacupuncture (EA) and moxibustion (Mox) on visceral hypersensitivity (their analgesic effects) in constipation-predominant irritable bowel syndrome (C-IBS). Methods. EA at 1 mA and 3 mA and Mox at 43°C and 46°C were applied to the Shangjuxu (ST37, bilateral) acupoint in rats with C-IBS and normal rats. An abdominal withdrawal reflex (AWR) score was used to assess visceral hypersensitivity. Toluidine blue staining was used to assess mast cell (MC) activity in colon of rats. Immunochemistry was used to measure 5-HT and 5-HT4 receptor expression in the colon. Results. AWR scores in all EA (1 mA and 3 mA) and Mox (43°C and 46°C) treatment groups after colorectal distention (CRD) stimulation pressure of 20, 40, 60, and 80 mmHg were significantly lower than those of the model (MC) group (P all < 0.01). The MC counts and degranulation rates in the colon of all EA and Mox treatment groups and the MC group were significantly higher than those of the NC group (P all < 0.01). MC degranulation rates in the colon of all EA and Mox treatment groups were lower than those of the MC group (P all < 0.05). 5-HT expression in colon of all EA and Mox treatment groups was significantly lower than that of the MC group (P all < 0.01), and 5-HT4R expression in colon of both EA groups was significantly higher than that of the MC group (P both < 0.01). Conclusion. EA and Mox treatments may both ameliorate visceral hypersensitivity at different degree in rats with C-IBS, and EA treatment was better than Mox.

The joint power of sex and stress to modulate brain-gut-microbiota axis and intestinal barrier homeostasis: implications for irritable bowel syndrome

BACKGROUND

Intestinal homeostasis is a dynamic process that takes place at the interface between the lumen and the mucosa of the gastrointestinal tract, where a constant scrutiny for antigens and toxins derived from food and microorganisms is carried out by the vast gut-associated immune system. Intestinal homeostasis is preserved by the ability of the mucus layer and the mucosal barrier to keep the passage of small-sized and antigenic molecules across the epithelium highly selective. When combined and preserved, immune surveillance and barrier's selective permeability, the host capacity of preventing the development of intestinal inflammation is optimized, and viceversa. In addition, the brain-gut-microbiome axis, a multidirectional communication system that integrates distant and local regulatory networks through neural, immunological, metabolic, and hormonal signaling pathways, also regulates intestinal function. Dysfunction of the brain-gut-microbiome axis may induce the loss of gut mucosal homeostasis, leading to uncontrolled permeation of toxins and immunogenic particles, increasing the risk of appearance of intestinal inflammation, mucosal damage, and gut disorders. Irritable bowel syndrome is prevalent stress-sensitive gastrointestinal disorder that shows a female predominance. Interestingly, the role of stress, sex and gonadal hormones in the regulation of intestinal mucosal and the brain-gut-microbiome axis functioning is being increasingly recognized.

PURPOSE

We aim to critically review the evidence linking sex, and stress to intestinal barrier and brain-gut-microbiome axis dysfunction and the implications for irritable bowel syndrome.

Mast Cells and Irritable Bowel Syndrome: From the Bench to the Bedside

Irritable bowel syndrome (IBS) is traditionally defined as a functional disorder since it lacks demonstrable pathological abnormalities. However, in recent years, low grade inflammatory infiltration, often rich in mast cells, in both the small and large bowel, has been observed in some patients with IBS. The close association of mast cells with major intestinal functions, such as epithelial secretion and permeability, neuroimmune interactions, visceral sensation, and peristalsis, makes researchers and gastroenterologists to focus attention on the key roles of mast cells in the pathogenesis of IBS. Numerous studies have been carried out to identify the mechanisms in the development, infiltration, activation, and degranulation of intestinal mast cells, as well as the actions of mast cells in the processes of mucosal barrier disruption, mucosal immune dysregulation, visceral hypersensitivity, dysmotility, and local and central stress in IBS. Moreover, therapies targeting mast cells, such as mast cell stabilizers (cromoglycate and ketotifen) and antagonists of histamine and serotonin receptors, have been tried in IBS patients, and have partially exhibited considerable efficacy. This review focuses on recent advances in the role of mast cells in IBS, with particular emphasis on bridging experimental data with clinical therapeutics for IBS patients.

Stress and the Microbiota-Gut-Brain Axis in Visceral Pain: Relevance to Irritable Bowel Syndrome

Visceral pain is a global term used to describe pain originating from the internal organs of the body, which affects a significant proportion of the population and is a common feature of functional gastrointestinal disorders (FGIDs) such as irritable bowel syndrome (IBS). While IBS is multifactorial, with no single etiology to completely explain the disorder, many patients also experience comorbid behavioral disorders, such as anxiety or depression; thus, IBS is described as a disorder of the gut-brain axis. Stress is implicated in the development and exacerbation of visceral pain disorders. Chronic stress can modify central pain circuitry, as well as change motility and permeability throughout the gastrointestinal (GI) tract. More recently, the role of the gut microbiota in the bidirectional communication along the gut-brain axis, and subsequent changes in behavior, has emerged. Thus, stress and the gut microbiota can interact through complementary or opposing factors to influence visceral nociceptive behaviors. This review will highlight the evidence by which stress and the gut microbiota interact in the regulation of visceral nociception. We will focus on the influence of stress on the microbiota and the mechanisms by which microbiota can affect the stress response and behavioral outcomes with an emphasis on visceral pain.

Mast cell activation is involved in stress-induced epithelial barrier dysfunction in the esophagus

OBJECTIVE

We aimed to investigate the role of mast cell in stress-induced barrier dysfunction in the esophagus and its possible pathway involved using mast cell-deficient (Ws/Ws) rats.

METHODS

Ws/Ws rats and normal (+/+) rats were submitted to chronic restraint stress (CRS) 2 h/day for 7 days. Tissues were obtained from distal esophagus. Mast cells were counted under Alcian blue-safranin O stain. Activation of mast cells was assessed using transmission electron microscope. Esophageal epithelial barrier dysfunction was evaluated by measuring intercellular spaces (ICS) and by quantifying tight junction (TJ) proteins. The localization and expression of mast cell-derived tryptase and proteinase activated receptor 2 (PAR-2) were assessed.

RESULTS

A higher number of mast cells and higher proportion of activated mast cells were observed in CRS +/+ rats compared with non-stress controls. Increased ICS and decreased expression of some TJ proteins were observed in the CRS +/+ rats but not in the CRS Ws/Ws rats. Tryptase and its receptor PAR-2 were found elevated concomitantly by nearly 100% in CRS +/+ rats, but not in CRS Ws/Ws rats.

CONCLUSIONS

Mast cells play an important role in stress-induced epithelial barrier dysfunction in esophagus. The mechanism may involve the activation of PAR-2 by mast cell-derived tryptase, causing proinflammatory responses and the subsequent disruption of the epithelial TJ proteins and a disturbed cytoskeleton function, resulting in dilated intercellular spaces.

Role of Corticotropin-releasing Factor Signaling in Stress-related Alterations of Colonic Motility and Hyperalgesia

The corticotropin-releasing factor (CRF) signaling systems encompass CRF and the structurally related peptide urocortin (Ucn) 1, 2, and 3 along with 2 G-protein coupled receptors, CRF₁ and CRF₂. CRF binds with high and moderate affinity to CRF₁ and CRF₂ receptors, respectively while Ucn1 is a high-affinity agonist at both receptors, and Ucn2 and Ucn3 are selective CRF₂ agonists. The CRF systems are expressed in both the brain and the colon at the gene and protein levels. Experimental studies established that the activation of CRF₁ pathway in the brain or the colon recaptures cardinal features of diarrhea predominant irritable bowel syndrome (IBS) (stimulation of colonic motility, activation of mast cells and serotonin, defecation/watery diarrhea, and visceral hyperalgesia). Conversely, selective CRF₁ antagonists or CRF₁/CRF₂ antagonists, abolished or reduced exogenous CRF and stress-induced stimulation of colonic motility, defecation, diarrhea and colonic mast cell activation and visceral hyperalgesia to colorectal distention. By contrast, the CRF₂ signaling in the colon dampened the CRF₁ mediated stimulation of colonic motor function and visceral hyperalgesia. These data provide a conceptual framework that sustained activation of the CRF₁ system at central and/or peripheral sites may be one of the underlying basis of IBS-diarrhea symptoms. While targeting these mechanisms by CRF₁ antagonists provided a relevant novel therapeutic venue, so far these promising preclinical data have not translated into therapeutic use of CRF₁ antagonists. Whether the existing or newly developed CRF₁ antagonists will progress to therapeutic benefits for stress-sensitive diseases including IBS for a subset of patients is still a work in progress.

Selective agonists of somatostatin receptor subtype 1 or 2 injected peripherally induce antihyperalgesic effect in two models of visceral hypersensitivity in mice

Somatostatin interacts with five G-protein-coupled receptor (sst1-5). Octreotide, a stable sst2≫3≥5 agonist, exerts a visceral anti-hyperalgesic effect in experimental and clinical studies. Little is known on the receptor subtypes involved. We investigated the influence of the stable sst1-5 agonist, ODT8-SST and selective receptor subtype peptide agonists (3 or 10μg/mouse) injected intraperitoneally (ip) on visceral hypersensitivity in mice induced by repeated noxious colorectal distensions (four sets of three CRD, each at 55mmHg) or corticotropin-releasing factor receptor 1 agonist, cortagine given between two sets of graded CRD (15, 30, 45, and 60mmHg, three times each pressure). The mean visceromotor response (VMR) was assessed using a non-invasive manometry method and values were expressed as percentage of the VMR to the 1st set of CRD baseline or to the 60mmHg CRD, respectively. ODT8-SST (10μg) and the sst2 agonist, S-346-011 (3 and 10μg) prevented mechanically induced visceral hypersensitivity in the three sets of CRD, the sst1 agonist (10μg) blocked only the 2nd set and showed a trend at 3μg while the sst4 agonist had no effect. The selective sst2 antagonist, S-406-028 blocked the sst2 agonist but not the sst1 agonist effect. The sst1 agonist (3 and 10μg) prevented cortagine-induced hypersensitivity to CRD at each pressure while the sst2 agonist at 10μg reduced it. These data indicate that in addition to sst2, the sst1 agonist may provide a novel promising target to alleviate visceral hypersensitivity induced by mechanoreceptor sensitization and more prominently, stress-related visceral nociceptive sensitization.

Role of insular cortex in visceral hypersensitivity model in rats subjected to chronic stress

Abnormal processing of visceral sensation at the level of the central nervous system has been proven to be important in the pathophysiologic mechanisms of stress related functional gastrointestinal disorders. However, the specific mechanism is still not clear. The insular cortex (IC) was considered as one important visceral sensory area. Moreover, the IC has been shown to be involved in various neuropsychiatric diseases such as panic disorders and post-traumatic stress disorder. However, whether the IC is important in psychological stress related visceral hypersensitivity has not been studied yet. In our study, through destruction of the bilateral IC, we explored whether the IC played a critical role in the formation of visceral hypersensitivity induced by chronic stress on rats. Chronic partial restraint stress was used to establish viscerally hypersensitive rat model. Bilateral IC lesions were generated by N-methyl-D-day (door) aspartate. After a recovery period of 7 days, 14-day consecutive restraint stress was performed. The visceromotor response to colorectal distension was monitored by recording electromyogram to measure rats׳ visceral sensitivity. We found that bilateral insular cortex lesion could markedly inhibit the formation of visceral hypersensitivity induced by chronic stress. The insular cortex plays a critical role in the pathophysiology of stress-related visceral hypersensitivity.

A balance theory of peripheral corticotropin-releasing factor receptor type 1 and type 2 signaling to induce colonic contractions and visceral hyperalgesia in rats

Several recent studies suggest that peripheral corticotropin-releasing factor (CRF) receptor type 1 (CRF1) and CRF2 have a counter regulatory action on gastrointestinal functions. We hypothesized that the activity balance of each CRF subtype signaling may determine the changes in colonic motility and visceral sensation. Colonic contractions were assessed by the perfused manometry, and contractions of colonic muscle strips were measured in vitro in rats. Visceromotor response was determined by measuring contractions of abdominal muscle in response to colorectal distensions (CRDs) (60 mm Hg for 10 min twice with a 30-min rest). All drugs were administered through ip route in in vivo studies. CRF increased colonic contractions. Pretreatment with astressin, a nonselective CRF antagonist, blocked the CRF-induced response, but astressin2-B, a selective CRF2 antagonist, enhanced the response by CRF. Cortagine, a selective CRF1 agonist, increased colonic contractions. In in vitro study, CRF increased contractions of muscle strips. Urocortin 2, a selective CRF2 agonist, itself did not alter the contractions but blocked this increased response by CRF. Visceromotor response to the second CRD was significantly higher than that of the first. Astressin blocked this CRD-induced sensitization, but astressin2-B or CRF did not affect it. Meanwhile, astressin2-B together with CRF significantly enhanced the sensitization. Urocortin 2 blocked, but cortagine significantly enhanced, the sensitization. These results indicated that peripheral CRF1 signaling enhanced colonic contractility and induced visceral sensitization, and these responses were modulated by peripheral CRF2 signaling. The activity balance of each subtype signaling may determine the colonic functions in response to stress.

Impact of psychological stress on irritable bowel syndrome

Psychological stress is an important factor for the development of irritable bowel syndrome (IBS). More and more clinical and experimental evidence showed that IBS is a combination of irritable bowel and irritable brain. In the present review we discuss the potential role of psychological stress in the pathogenesis of IBS and provide comprehensive approaches in clinical treatment. Evidence from clinical and experimental studies showed that psychological stresses have marked impact on intestinal sensitivity, motility, secretion and permeability, and the underlying mechanism has a close correlation with mucosal immune activation, alterations in central nervous system, peripheral neurons and gastrointestinal microbiota. Stress-induced alterations in neuro-endocrine-immune pathways acts on the gut-brain axis and microbiota-gut-brain axis, and cause symptom flare-ups or exaggeration in IBS. IBS is a stress-sensitive disorder, therefore, the treatment of IBS should focus on managing stress and stress-induced responses. Now, non-pharmacological approaches and pharmacological strategies that target on stress-related alterations, such as antidepressants, antipsychotics, miscellaneous agents, 5-HT synthesis inhibitors, selective 5-HT reuptake inhibitors, and specific 5-HT receptor antagonists or agonists have shown a critical role in IBS management. A integrative approach for IBS management is a necessary.

Randomized clinical trial on the effect of a multispecies probiotic on visceroperception in hypersensitive IBS patients

BACKGROUND

Irritable bowel syndrome (IBS) is characterized by heterogeneous pathophysiology and low response to treatment. Up to 60% of IBS patients suffers from visceral hypersensitivity, which is associated with symptom severity and underlying pathophysiological mechanisms. Recently, positive effects of probiotics in IBS have been reported, but overall the response was modest. We performed a study in IBS patients, characterized by visceral hypersensitivity measured with the rectal barostat, aiming to assess the effect of 6 weeks of multispecies probiotic mix on visceral pain perception.

METHODS

We conducted a randomized, placebo-controlled, double-blind trial in forty Rome III IBS patients with visceral hypersensitivity. Prior to intake, patients kept a 2-week symptom diary and underwent a rectal barostat measurement. When hypersensitivity was confirmed, participation was allowed and patients received a multispecies probiotic with in vitro proven potential beneficial effects on mechanisms contributing to visceral hypersensitivity (six different probiotic strains; 10(9)  cfu/g), or a placebo product of one sachet (5 g) per day for 6 weeks. At the end of the intervention period, visceroperception and symptoms were reassessed.

KEY RESULTS

Thirty-five patients completed the trial. The percentage of patients with visceral hypersensitivity decreased significantly in the probiotic and placebo group (76.5% and 71.4%, respectively; N.S. between groups). Improvement in pain scores and mean symptom score did not differ between the probiotic and placebo group.

CONCLUSIONS & INFERENCES

In this placebo-controlled trial in IBS patients with visceral hypersensitivity, no significant effect of a multispecies probiotic on viscerperception was observed. The study has been registered in the US National Library of Medicine (http://www.clinicaltrials.gov, NCT00702026).

Expression of G protein-coupled estrogen receptor in irritable bowel syndrome and its clinical significance

OBJECTIVES

Estrogen is suggested to participate in pathogenesis of irritable bowel syndrome (IBS), but expression of G protein-coupled estrogen receptor (GPER) in the colon of IBS patients has never been investigated. The aim of this study was to investigate the expression of GPER and classical estrogen receptors in the colon of IBS patients and healthy controls.

METHODS

Colonic biopsies were obtained by endoscopy from patients with IBS (n=46) and healthy subjects (n=13). Expression of GPER, estrogen receptor α (ERα) and estrogen receptor β (ERβ) in mast cells were measured by double-labelling immunofluorescence. Quantification of mRNA expression was performed for GPER, ERα and ERβ by real-time polymerase chain reaction.

RESULTS

Differential distribution of GPER, ERα and ERβ were detected in human colonic mucosa. The expression of GPER in the cytoplasm of mast cells and GPER-positive cells was significantly higher in diarrhea-predominant IBS (D-IBS) patients than that in constipation-predominant IBS (C-IBS, P<0.001) patients and healthy subjects (P=0.005). ERα and ERβ were not detected in majority of mast cells in colonic mucosa and no difference of immunostaining results for ERα and ERβ was found among these three groups. A positive correlation (r=0.451, P=0.011) between GPER-positive cell counts and abdominal pain severity was observed in D-IBS group. Relative mRNA expression of GPER in D-IBS was also higher than that in C-IBS (P=0.018) and healthy subjects (P=0.011).

CONCLUSIONS

The present study, for the first time, demonstrated the expression of GPER in human colonic mucosa and its correlation with abdominal pain severity.

Sex hormones in the modulation of irritable bowel syndrome

Compelling evidence indicates sex and gender differences in epidemiology, symptomatology, pathophysiology, and treatment outcome in irritable bowel syndrome (IBS). Based on the female predominance as well as the correlation between IBS symptoms and hormonal status, several models have been proposed to examine the role of sex hormones in gastrointestinal (GI) function including differences in GI symptoms expression in distinct phases of the menstrual cycle, in pre- and post-menopausal women, during pregnancy, hormonal treatment or after oophorectomy. Sex hormones may influence peripheral and central regulatory mechanisms of the brain-gut axis involved in the pathophysiology of IBS contributing to the alterations in visceral sensitivity, motility, intestinal barrier function, and immune activation of intestinal mucosa. Sex differences in stress response of the hypothalamic-pituitary-adrenal axis and autonomic nervous system, neuroimmune interactions triggered by stress, as well as estrogen interactions with serotonin and corticotropin-releasing factor signaling systems are being increasingly recognized. A concept of “microgenderome” related to the potential role of sex hormone modulation of the gut microbiota is also emerging. Significant differences between IBS female and male patients regarding symptomatology and comorbidity with other chronic pain syndromes and psychiatric disorders, together with differences in efficacy of serotonergic medications in IBS patients confirm the necessity for more sex-tailored therapeutic approach in this disorder.

Eosinophils and mast cells as therapeutic targets in pediatric functional dyspepsia

There is an increasing appreciation for the importance of inflammation as a pathophysiologic entity that contributes to functional gastrointestinal disorders including functional dyspepsia (FD). Importantly, inflammation may serve as a mediator between psychologic and physiologic functions. This manuscript reviews the literature implicating two inflammatory cell types, mast cells and eosinophils, in the generation of dyspeptic symptoms and explores their potential as targets for the treatment of FD. There are a number of inciting events which may initiate an inflammatory response, and the subsequent recruitment and activation of mast cells and eosinophils. These include internal triggers such as stress and anxiety, as well as external triggers such as microbes and allergens. Previous studies suggest that there may be efficacy in utilizing medications directed at mast cells and eosinophils. Evidence exists to suggest that combining “anti-inflammatory” medications with other treatments targeting stress can improve the rate of symptom resolution in pediatric FD.