Alterations of sensori-motor functions of the digestive tract in the pathophysiology of irritable bowel syndrome

Helicobacter pylori Infection and Extragastric Diseases-A Focus on the Central Nervous System

Helicobacter pylori (H. pylori) is most known to cause a wide spectrum of gastrointestinal impairments; however, an increasing number of studies indicates that H. pylori infection might be involved in numerous extragastric diseases such as neurological, dermatological, hematologic, ocular, cardiovascular, metabolic, hepatobiliary, or even allergic diseases. In this review, we focused on the nervous system and aimed to summarize the findings regarding H. pylori infection and its involvement in the induction/progression of neurological disorders. Neurological impairments induced by H. pylori infection are primarily due to impairments in the gut-brain axis (GBA) and to an altered gut microbiota facilitated by H. pylori colonization. Currently, regarding a potential relationship between Helicobacter infection and neurological disorders, most of the studies are mainly focused on H. pylori.

Duodenal mucosal secretory disturbances in functional dyspepsia

BACKGROUND

There is increased recognition of duodenal disturbances (inflammation, altered mucosal protein expression, and chemosensitivity) in functional dyspepsia (FD). Besides sensorimotor functions, enteric submucosal neurons also regulate epithelial ion transport. We hypothesized that duodenal mucosal ion transport and expression of associated genes are altered in FD.

METHODS

Duodenal mucosal ion transport (basal and acetylcholine- and glucose-evoked changes in short-circuit current [Isc]) and expression of associated genes and regulatory miRNAs were evaluated in 40 FD patients and 24 healthy controls.

RESULTS

Basal Isc (FD: 88.2 [52.6] μA/cm² vs healthy: 20.3 [50.2] μA/cm² ; P ≤ .0001), acetylcholine-evoked Isc (FD: Emax 50.4 [35.8] μA/cm² vs healthy: 16.6 [15] μA/cm² ; P ≤ .001), and glucose-evoked Isc responses (FD: E_max 69.8 [42.1] μA/cm² vs healthy: 40.3 [24.6] μA/cm² ; P = .02) were greater in FD than in controls. The Emax for glucose was greater in FD patients on selective serotonin reuptake inhibitors. In FD, the mRNA expression of SLC4A7 and SLC4A4, which transport bicarbonate into cells at the basolateral surface, and the apical anion exchanger SLC26A3 were reduced (false discovery rate <0.05), the serotonin receptor HTR4 was increased, and the serotonin transporter SLC6A4 was decreased. Selected miRNAs (hsa-miR-590-3p, hsa-miR-32-5p) that target genes associated with ionic transport were upregulated in FD.

CONCLUSIONS

Compared to controls, FD patients had greater baseline and agonist-evoked duodenal mucosal secretory responses. These findings may be explained by reduced gene expression, which would be anticipated to reduce luminal bicarbonate secretion. The upregulated miRNAs may partly explain the downregulation of these genes in FD.

[Diet low in fermentable oligosaccharides, disaccharides, monosaccharides and polyols, and quality of life in patients with irritable bowel syndrome in Colombia]

INTRODUCTION

A growing body of evidence has pointed out the effectiveness of a diet low in fermentable oligosaccharides, disaccharides, monosaccharides and polyols (FODMAP) in patients with irritable bowel syndrome. However, there are no local studies to estimate the effects of this strategy on the symptoms and the health-related quality of life in these patients in Colombia or Latin America.

OBJECTIVE

To determine the effect of a diet low in FODMAP on the quality of life and the severity of symptoms in patients with irritable bowel syndrome in Colombia.

MATERIALS AND METHODS

We collected clinical and demographic information of all patients at the time of inclusion. Immediately afterwards, a trained interviewer applied the IBS-QoL survey to estimate the quality of life of patients. Then, we evaluated the intensity of the symptoms using an analogue visual scale, before and after the diet low in FODMAP.

RESULTS

We included 50 subjects in the final analysis. We observed an increase in all the IBS-QoL scales (average increase in overall summary: 14.7 points, 95% CI: 9.4 to 20.1; p<0.001) and a significant reduction in all symptoms (-19.8 mm; 95% CI: 23.4 mm 16.2 mm; p<0.001). Sex, age, body mass index, socioeconomic status and the health care provider were not associated with the improvement in the health-related quality of life.

CONCLUSION

A low diet in FODMAP reduced symptoms and improved quality of life in Colombian patients with irritable bowel syndrome. Controlled studies taking into account other factors linked to the severity of irritable bowel syndrome are required.

Histomorphological Spectrum of Duodenal Pathology in Functional Dyspepsia Patients

INTRODUCTION

Functional Dyspepsia (FD) is one of the most common causes of gastrointestinal symptoms aetiology of which is poorly understood.

AIM

To study duodenal histomorphological features and their relationship with Helicobacter pylori (H Pylori) infection in patients of FD.

MATERIALS AND METHODS

This case control study included 50 cases of FD patients selected according to Rome III criteria and 30 age and sex matched controls. These were subjected to oesophago-gastro-duodenoscopy, rapid urease test for detection of H. pylori on gastric antral biopsy and duodenal biopsy from second part of duodenum for histopathological evaluation by light microscopy. Ten antral urease positive cases of FD with highest Intraepithelial Lymphocyte Count (IEL) were subjected to Immunohistochemistry (IHC).

RESULTS

Duodenal inflammation was an invariable feature noted in FD. Morphological spectrum consisted of increased IEL in 72%, increased duodenal eosinophils in 92%, presence of focal villous atrophy in 16%, lymphoid aggregates, colonic metaplasia, and duodenal H. pylori infection in 4% each. Gastric H. pylori positivity was noted in 48% cases of FD. Increased duodenal IEL count and duodenal eosinophilia was noted in 75%, 87.5% such cases. Same was noted respectively, with 61.5% and 95.15% cases with gastric H. pylori negativity. In cases of FD, duodenal IEL and eosinophil count in lamina propria showed statistically significant rise when compared with control and had positive correlation with gastric H pylori infection. On IHC, increased expression of CD 8 was noted in duodenal IEL and lymphocytes in lamina propria as compared to CD4.

CONCLUSION

Our study provided some insight in pathogenesis of FD and role of H. pylori in its aetiology.

Biomarkers as a diagnostic tool for irritable bowel syndrome: where are we?

Irritable bowel syndrome (IBS) is a common condition in clinical practice. There are currently no objective tests to rule in the disease, but rather tests to rule out other diseases. Biomarkers in IBS may provide the tools needed for diagnosis, prognosis and therapy. These include identification of differences in microbial composition, immune activation, bile acid composition, colonic transit, and alteration in sensation in subgroups of IBS patients. Areas covered: Studies included in our review were chosen based on a PubMed search for 'biomarkers' and 'IBS'. We have reviewed the literature on biomarkers to appraise their accuracy, validity and whether they are actionable. We have not covered genetic associations as biomarkers in this review. Expert commentary: There is significant promise in the usefulness of biomarkers for IBS. The most promising actionable biomarkers are markers of changes in bile acid balance, such as elevated bile acid in the stool, and altered colonic transit. However, there is also potential for microbial studies and mucosal proteases as future actionable biomarkers.

Toll like receptor-2 regulates production of glial-derived neurotrophic factors in murine intestinal smooth muscle cells

Gut microbiota-innate immunity axis is emerging as a key player to guarantee the structural and functional integrity of the enteric nervous system (ENS). Alterations in the composition of the gut microbiota, derangement in signaling of innate immune receptors such as Toll-like receptors (TLRs), and modifications in the neurochemical coding of the ENS have been associated with a variety of gastrointestinal disorders. Indeed, TLR2 activation by microbial products controls the ENS structure and regulates intestinal neuromuscular function. However, the cellular populations and the molecular mechanisms shaping the plasticity of enteric neurons in response to gut microbes are largely unexplored. In this study, smooth muscle cells (SMCs), enteric glial cells (EGCs) and macrophages/dendritic cells (MΦ/DCs) were isolated and cultured from the ileal longitudinal muscle layer of wild-type (WT) and Toll-like receptor-2 deficient (TLR2(-/-)) mice. Quantification of mRNA levels of neurotrophins at baseline and following stimulation with TLR ligands was performed by RT-PCR. To determine the role of neurotrophins in supporting the neuronal phenotype, we performed co-culture experiments of enteric neurons with the conditioned media of cells isolated from the longitudinal muscle layer of WT or TLR2(-/-) mice. The neuronal phenotype was investigated evaluating the expression of βIII-tubulin, HuC/D, and nNOS by immunocytochemistry. As detected by semi-quantitative RT-PCR, SMCs expressed mRNA coding TLR1-9. Among the tested cell populations, un-stimulated SMCs were the most prominent sources of neurotrophins. Stimulation with TLR2, TLR4, TLR5 and TLR9 ligands further increased Gdnf, Ngf, Bdnf and Lif mRNA levels in SMCs. Enteric neurons isolated from TLR2(-/-) mice exhibited smaller ganglia, fewer HuC/D(+ve) and nNOS(+ve) neurons and shorter βIII-tubulin axonal networks as compared to neurons cultured from WT mice. The co-culture with the conditioned media from WT-SMCs but not with those from WT-EGCs or WT-MΦ/DCs corrected the altered neuronal phenotype of TLR2(-/-) mice. Supplementation of TLR2(-/-) neuronal cultures with GDNF recapitulated the WT-SMC co-culture effect whereas the knockdown of GDNF expression in WT-SMCs using shRNA interference abolished the effect on TLR2(-/-) neurons. These data revealed that by exploiting the repertoire of TLRs to decode gut-microbial signals, intestinal SMCs elaborate a cocktail of neurotrophic factors that in turn supports neuronal phenotype. In this view, the SMCs represent an attractive target for novel therapeutic strategies.

Chronic functional bowel syndrome enhances gut-brain axis dysfunction, neuroinflammation, cognitive impairment, and vulnerability to dementia

The irritable bowel syndrome (IBS) is a common chronic functional gastrointestinal disorder world wide that lasts for decades. The human gut harbors a diverse population of microbial organisms which is symbiotic and important for well being. However, studies on conventional, germ-free, and obese animals have shown that alteration in normal commensal gut microbiota and an increase in pathogenic microbiota-termed "dysbiosis", impact gut function, homeostasis, and health. Diarrhea, constipation, visceral hypersensitivity, and abdominal pain arise in IBS from the gut-induced dysfunctional metabolic, immune, and neuro-immune communication. Dysbiosis in IBS is associated with gut inflammation. Gut-related inflammation is pivotal in promoting endotoxemia, systemic inflammation, and neuroinflammation. A significant proportion of IBS patients chronically consume alcohol, non-steroidal anti-inflammatories, and fatty diet; they may also suffer from co-morbid respiratory, neuromuscular, psychological, sleep, and neurological disorders. The above pathophysiological substrate is underpinned by dysbiosis, and dysfunctional bidirectional "Gut-Brain Axis" pathways. Pathogenic gut microbiota-related systemic inflammation (due to increased lipopolysaccharide and pro-inflammatory cytokines, and barrier dysfunction), may trigger neuroinflammation enhancing dysfunctional brain regions including hippocampus and cerebellum. These as well as dysfunctional vago-vagal gut-brain axis may promote cognitive impairment. Indeed, inflammation is characteristic of a broad spectrum of neurodegenerative diseases that manifest demntia. It is argued that an awareness of pathophysiological impact of IBS and implementation of appropriate therapeutic measures may prevent cognitive impairment and minimize vulnerability to dementia.

Inflammation- and axotomy-induced changes in cocaine- and amphetamine-regulated transcript peptide-like immunoreactive (CART-LI) nervous structures in the porcine descending colon

This study reports on changes in CART-like immunoreactive (CART-LI) nerve structures in the porcine descending colon during chemically driven inflammation and after axotomy. The distribution pattern of CART-LI nerve structures was studied using doublelabeling immunofluorescence technique in the circular muscle layer, myenteric (MP), outer submucous (OSP) and inner submucous plexuses (ISP) and also in the mucosal layer of the porcine descending colon in physiological conditions as well as under pathological factors. In the control animals, CART-LI perikarya have been shown to constitute 5.11% +/- 0.64, 4.03% +/- 1.17 and 0.05% +/- 0.04 in MP, OSP and ISP, respectively. Changes in CART-immunoreactivity depended on the pathological factor and the part of the enteric nervous system (ENS) studied. Numbers of CART-LI perikarya amounted to 2.77% +/- 0.64, 2.60% +/- 0.36 and 0.26% +/- 0.19 during chemically-induced colitis and 3.04% +/- 0.88, 2.46% +/- 0.8 and 0.43% +/- 0.09 after axotomy in MP, OSP and ISP, respectively. Both studied pathological processes also caused an increase in the number of CART-LI nerve fibers in the circular muscle as well as in the mucosal layer.

SERT and TPH-1 mRNA expression are reduced in irritable bowel syndrome patients regardless of visceral sensitivity state in large intestine

Colorectal visceral hypersensitivity has been demonstrated in a subset of irritable bowel syndrome (IBS) patients. Serine protease and serotonergic signaling modulate gastrointestinal visceral sensitivity. We evaluated whether altered mucosal serine protease and serotonergic pathway components are related to rectal visceral hypersensitivity in IBS patients. Colorectal mucosal biopsies of 23 IBS patients and 15 controls were collected. Gene transcripts of protease-activated receptor (PAR)-2, trypsinogen IV, tryptophan hydroxylase (TPH)-1, and serotonin reuptake transporter (SERT) were quantified using real-time polymerase chain reaction. Substance P and 5-HT contents were measured by ELISA. The number of enterochromaffin cells, mast cells, and intraepithelial lymphocytes was determined using immunohistochemistry. Rectal visceral sensitivity was determined in IBS patients using barostat programmed for phasic ascending distension. Rectal hypersensitivity (+) and (-) IBS patients showed lower TPH-1 and SERT mRNA levels in the rectum compared with controls (P ≤ 0.05). Rectal hypersensitivity (+) IBS patients (n = 12) showed lower TPH-1 mRNA level in the sigmoid compared with controls (P = 0.015). No significant differences were observed in PAR-2 and trypsinogen IV expression between controls and IBS patients. Rectal substance P content was increased in IBS patients compared with controls (P = 0.045). No significant differences were found in transcript levels, cell counts, and substance P and 5-HT contents between rectal hypersensitivity (+) and (-) IBS patients. In conclusion, regardless of visceral hypersensitivity state, several serotonergic signaling components are altered in IBS patients.

Maternal separation as a model of brain-gut axis dysfunction

RATIONALE

Early life stress has been implicated in many psychiatric disorders ranging from depression to anxiety. Maternal separation in rodents is a well-studied model of early life stress. However, stress during this critical period also induces alterations in many systems throughout the body. Thus, a variety of other disorders that are associated with adverse early life events are often comorbid with psychiatric illnesses, suggesting a common underlying aetiology. Irritable bowel syndrome (IBS) is a functional gastrointestinal disorder that is thought to involve a dysfunctional interaction between the brain and the gut. Essential aspects of the brain-gut axis include spinal pathways, the hypothalamic pituitary adrenal axis, the immune system, as well as the enteric microbiota. Accumulating evidence suggest that stress, especially in early life, is a predisposing factor to IBS.

OBJECTIVE

The objective of this review was to assess and compile the most relevant data on early life stress and alterations at all levels of the brain gut axis.

RESULTS

In this review, we describe the components of the brain-gut axis individually and how they are altered by maternal separation. The separated phenotype is characterised by alterations of the intestinal barrier function, altered balance in enteric microflora, exaggerated stress response and visceral hypersensitivity, which are all evident in IBS.

CONCLUSION

Thus, maternally separated animals are an excellent model of brain-gut axis dysfunction for the study of disorders such as IBS and for the development of novel therapeutic interventions.

Anorectal function and visceral hypersensitivity in celiac disease

OBJECTIVE

To evaluate anorectal function and rectal sensitivity thresholds in patients with celiac disease (CD).

METHODS

In 25 unselected patients with CD (16 female, 9 male; mean age 45, range 24 to 75 y) and 20 controls (12 female, 8 male; mean age 41, range 20 to 65 y) anorectal manometry and rectal balloon distension test were conducted using a 4 lumen water perfused catheter with a polyethylene balloon (Zinectics Manometric Catheter, Medtronic).

RESULTS

In celiac patients the maximal anal resting pressure, reflecting the internal anal sphincter function, was significantly higher than that in the controls: 87.8±21.7 mm Hg versus 66.7±15.2 mm Hg (P<0.001). There were no considerable differences between both the groups neither in the maximal anal squeeze nor in the cough pressures. Celiac patients had significantly lower first sensation threshold: 25.6±10.8 mL versus 37.5±12.5 mL (P<0.05). Visceral hypersensitivity (rectal pain/discomfort threshold ≤100 mL) was observed in 36% of celiac patients and in none of the controls (P<0.01).

CONCLUSIONS

The increased anal resting pressure and rectal hypersensitivity are observed in CD. Disturbances in gastrointestinal motility and visceral perception in the course of CD may occur at different levels of the brain-gut axis including direct changes in the enteric nervous system.

Migration of eosinophils and CCR2-/CD68-double positive cells into the duodenal mucosa of patients with postinfectious functional dyspepsia

OBJECTIVES

Recent studies have shown that postinfectious functional dyspepsia (FD) symptoms may persist after elimination of gastrointestinal (GI) infection as well as postinfectious irritable bowel syndrome accompanying colonic inflammation. However, it is unclear whether intestinal chronic inflammation can contribute to clinical symptoms of certain FD patients such as postinfectious FD. To determine the relationship between local inflammation of the duodenum and clinical symptoms, we evaluated the infiltration of several phenotypes of duodenal inflammatory cells as well as gastric motility using (13)C urea breath test in postinfectious FD patients.

METHODS

We enrolled 136 consecutive patients diagnosed with FD according to Rome III criteria, and 20 healthy controls, after upper GI endoscopy. Gastric motility was evaluated by gastric emptying time (T-max) using the (13)C-acetate breath test. Upper abdominal symptoms including epigastric pain, epigastric burning, postprandial fullness, abdominal distension, and early satiety were assessed by questionnaire scores. We obtained biopsy specimens from the stomach and duodenum during upper GI endoscopy. Histological gastritis and duodenitis were assessed as mild, moderate, or severe according to previously described criteria. Characteristics of inflammatory cells and neuroendocrine cells were determined immunohistochemically with antibodies to CD3, CD68, CCR2, Vdelta1 TCR, and serotonin.

RESULTS

Endoscopic duodenitis was observed in only 5.7% of postinfectious FD patients. However, the rates of histological duodenitis in duodenal biopsies of postinfectious FD patients were 17% for mild, 26% for moderate, and 57% for severe grades of duodenitis. The degree of histological duodenitis of postinfectious FD patients was significantly greater than that of healthy volunteers. There was a significant correlation between epigastric burning and the degree of duodenitis in postinfectious FD patients. There was no significant difference in histological duodenitis and T-max value in the postinfectious FD patients with or without Helicobacter pylori infection. In addition, CD68-positive cell number in postinfectious FD patients was significantly increased compared with the numbers in subjects with epigastric pain syndrome or postprandial distress syndrome and in healthy volunteers. CCR2-/CD68-double positive cell number in postinfectious FD patients was significantly (P=0.009) increased compared with those in healthy volunteers.

CONCLUSIONS

Migration of inflammatory cells, in particular, duodenal CCR2-positive macrophages, may have an important function in the pathophysiology of postinfectious FD patients.

Testing a biobehavioral model of irritable bowel syndrome

OBJECTIVE

The pathogenesis of irritable bowel syndrome (IBS) is probably multifactorial with dysfunction at different levels of the brain-gut axis. The aim of this study was to evaluate an existing biobehavioral model of IBS symptom generation in a large group of patients.

MATERIAL AND METHODS

In 104 IBS patients, we assessed symptom severity by a symptom diary, visceral hypersensitivity using a barostat, autonomic function by measuring arterial baroreflex sensitivity and psychological functioning using questionnaires. Structural equation modeling was used to calculate the reciprocal and chronological relationships between the model variables.

RESULTS

Analysis of the adjusted original model indicated poor fit [Satorra-Bentler chi=28.47; degrees of freedom (df)=11, P<0.01; comparative fit index (CFI)=0.78], which was caused by omission of two paths (illness behavior-IBS symptoms and trauma-IBS symptoms). The revised model yielded a reasonable fit (chi=13.88, df=9, P=0.13; CFI=0.94). The model explained 18.7% of the variance in IBS symptoms. Illness behavior completely mediated the effect of cognitions on IBS symptoms and partly mediated the effect of trauma on IBS symptoms. The fit of this alternative model was good (chi=9.85, df=8, P=0.28; CFI=0.98). The alternative model explained 20.0% of the variance in IBS symptoms.

CONCLUSION

The proposed biobehavioral model could not be validated. Although visceral hypersensitivity and IBS symptom severity significantly correlate, autonomic function and IBS symptoms do not. Cognitive-behavioral aspects are important in the clinical expression of IBS, with illness behavior playing an intermediate and central role.

Update on irritable bowel syndrome and gender differences

Irritable bowel syndrome (IBS) is a chronic functional GI disorder characterized by abdominal pain associated with alterations in defecation or stool frequency and consistency. In Western industrialized countries, women seek health care services for their symptoms more frequently than men. The cause of IBS is likely multifactorial involving altered motility, visceral hypersensitivity, and dysregulation of the autonomic nervous system. Many patients note that their symptoms are exacerbated by diet and stress, and women frequently report menstrual cycle fluctuations in symptoms. Current approaches to IBS management include behavioral management therapies such as dietary intake changes and stress reduction cognitive restructuring. Drug therapies are targeted at altering pain sensitivity, motility, and secretion. This review provides an overview of the pathogenesis of IBS, factors that contribute to gender differences, and current therapeutic approaches for symptom management.

Relation between clinical symptoms and experimental visceral hypersensitivity in pediatric patients with functional abdominal pain

OBJECTIVE

The association between clinical symptoms and laboratory visceral sensitivity remains poorly defined and controversial. It has even been suggested that laboratory observations of visceral sensitivity are irrelevant to the clinical presentation of chronic visceral pain. To better understand this association, gastrointestinal and psychological features of pediatric patients' clinical presentation were examined in relation to a laboratory-based measure of visceral sensitivity.

PATIENTS AND METHODS

At the time of their medical evaluation, 101 patients with medically unexplained abdominal pain (ages 8-15 years) completed validated questionnaires assessing recent depressive symptoms, functional disability, pain efficacy beliefs, gastrointestinal (GI), and non-GI symptoms. These clinical features were examined in relation to visceral sensitivity assessed 2 months later in the laboratory. The measure of visceral sensitivity was based on increases in GI complaints in response to the water load symptom provocation task.

RESULTS

More severe GI symptoms and functional disability in the weeks before patients' clinical evaluation were associated with significantly greater increases in GI symptoms in the laboratory in response to the water load symptom provocation task (all P < 0.04). Patients believing that they had the ability to alleviate their pain (high problem-focused pain efficacy) had significantly lower laboratory visceral sensitivity (P < 0.01). Clinical depressive symptoms and non-GI symptoms were not associated with laboratory visceral sensitivity.

CONCLUSIONS

Clinical presentations of more severe GI symptoms and disability as well as low perceived pain efficacy are significant predictors of laboratory visceral sensitivity in children with functional abdominal pain. Depression does not account for the association between clinical presentation of GI symptoms and a laboratory measure of visceral sensitivity.

Sympathetic (electrodermal) activity during repeated maximal rectal distensions in patients with irritable bowel syndrome and constipation

Irritable bowel syndrome (IBS) is associated with visceral hypersensitivity, stress and autonomic dysfunction. Sympathetic activity during repeated events indicates excitatory or inhibitory mechanisms such as sensitization or habituation. We investigated skin conductance (SC) during repetitive rectal distensions at maximal tolerable pressure in patients with IBS and chronic constipation. Twenty-seven IBS patients, 13 constipation patients and 18 controls underwent two sets of isobaric rectal distensions. First, maximal tolerable distension was determined and then it was repeated five times. Skin conductance was measured continuously. Subjective symptom assessment remained steady in all groups. The baseline values of SC were higher in IBS patients than in patients with constipation and significantly lower in constipation patients than in controls. The maximal SC response to repetitive maximal distensions was higher in IBS patients compared with constipation patients. The amplitude of the initial SC response decreased successively with increased number of distensions in patients with IBS and constipation but not in controls. Irritable bowel syndrome and constipation patients habituated to maximal repetitive rectal distensions with decreasing sympathetic activity. Irritable bowel syndrome patients had higher sympathetic reactivity and baseline activity than constipation patients. A lower basal SC in constipation patients compared with controls suggests an inhibition of the sympathetic drive in constipation patients.

Pain in chronic pancreatitis: a salutogenic mechanism or a maladaptive brain response?

Pain in chronic pancreatitis is frequently refractory to medical and even surgical treatment. This refractoriness leads us to believe that a pancreas-independent, brain-mediated mechanism must be responsible. If so, several scenarios are worth considering. First, chronic pain could be the consequence of undesirable neuroplastic changes, by which pathology becomes established and causes disability. Alternatively, pain may be linked to the salutogenic (from salutogenesis, the Latin word for health and well-being) central nervous system response (we defined 'salutogenic response' as the specific modulation of the immune system induced by brain activity changes) to promote healing of the injured viscera. If so, chronic pain could index the ongoing nervous system attempt to promote healing. In this review, we discuss (1) the mechanisms of pain in chronic pancreatitis; (2) potential brain-related salutogenic mechanisms, and (3) the potential relationship of these two factors to the disease status. Furthermore, we consider these aspects in light of a new approach to treat visceral pain: transcranial magnetic stimulation, a noninvasive method of brain stimulation.

Acute exacerbation of pain in irritable bowel syndrome: efficacy of phloroglucinol/trimethylphloroglucinol. A randomized, double-blind, placebo-controlled study

BACKGROUND

Abdominal pain is the predominant symptom in irritable bowel syndrome patients. Phloroglucinol and its methylated derivative are antispasmodic agents acting on smooth muscle.

AIM

To evaluate the efficacy of phloroglucinol/trimethylphloroglucinol on pain intensity during an acute exacerbation of pain of irritable bowel syndrome over a 1-week period treatment.

METHODS

Irritable bowel syndrome Rome II patients seeking medical advice for an acute exacerbation of abdominal pain were randomized to phloroglucinol/trimethylphloroglucinol (62.2 mg P + 80 mg TMP) two pills three times daily or placebo for 7 days. Patients were included if they had a pain with a minimal intensity of 40 on a 100-mm visual analogue scale, and if pain occurred at least 2 days during the week previous inclusion.

RESULTS

Three hundred and seven patients were included by 78 general practitioners. The intent-to-treat population included 300 patients, aged of 46.9 +/- 14.8 years (73% female). The relative decrease of pain intensity at day 7 was 57.8 +/- 31.7% vs. 46.3 +/- 34.7% (Delta = 11.5 +/- 3.8%, [CI(95%): 4.0 ; 19.1], P = 0.0029) and the percentage of patients with at least a 50% decrease of pain intensity was 62% vs. 47% (Delta = 15.3 +/- 5.7%, [CI(95%): 4.1 ; 26.5], P = 0.0078) in phloroglucinol/trimethylphloroglucinol and placebo groups, respectively.

CONCLUSIONS

A 1-week phloroglucinol/trimethylphloroglucinol treatment significantly reduces pain intensity in irritable bowel syndrome patients consulting their general practitioners for pain exacerbation.

Duodenal intraepithelial T lymphocytes in patients with functional dyspepsia

AIM: To quantify the intraepithelial lymphocytes (IELs) and to document the membrane expression of CD4, CD8, TCRγδ and adhesion and/or activation-associated molecules (CD103, CD28, CD44, CD69, HLA-DR, CD95/Fas) in the duodenal mucosa of patients with functional dyspepsia (FD) in order to provide arguments for an immunological process in FD.

METHODS: Twenty-six FD patients according to Rome II criteria (20 were H pylori negative) were studied and compared to 12 healthy adults. IELs were isolated from five duodenal biopsy samples, then quantified by microscopy and flow cytometry while the membrane phenotypes were determined by cytofluorometry.

RESULTS: Duodenal histological examination was normal. In H pylori negative patients, the number of IELs was not different from that in healthy controls. Median percentage expression of CD4, CD8, or TCRγδ and CD103, CD44, CD28, CD69 on CD3+ IELs, among the adhesion/activation associated molecules tested, was not different from that in healthy controls. In contrast, the median percentage expression of CD95/Fas [22 (9-65) vs 45 (19-88), P = 0.03] and HLA-DR expressing CD3+ IELs [4 (0-30) vs 13 (4-42), P = 0.04] was significantly lower in the H pylori negative FD group than in healthy controls, respectively. The number of IELs was significantly greater in H pylori positive FD patients than in healthy controls [median ratiofor 100 enterocytes 27.5 (6.7-62.5) vs 10.8 (3-33.3), P = 0.02] due to a higher number of CD8+ CD3+ IELs.

CONCLUSION: In H pylori negative FD patients, the phenotypic characterization of IELs suggests that we cannot exclude a role of IELs in FD.

Somatic referral of visceral sensations and rectal sensory threshold for pain in children with functional gastrointestinal disorders

OBJECTIVE

To test the hypothesis that abdominal pain related to functional gastrointestinal disorders is associated with visceral hypersensitivity and abnormal perception of visceral sensations.

STUDY DESIGN

We examined 35 children (10-17.6 years old) fulfilling the Rome II criteria with irritable bowel syndrome (IBS; n = 21), functional abdominal pain (FAP; n = 8) or functional dyspepsia (FD; n = 6) compared with 10 control subjects (10.2-16.1 years). All underwent a rectal barostat examination. Painful sensations were reported on a human body diagram. The projections of sensations induced by rectal distension, the rectal sensory threshold for pain (RSTP) and the diagnostic value of RSTP measurements were measured.

RESULTS

Rectal distension induced sensations that projected to the S3 dermatome in the control subjects and FD and to aberrant sites in children with IBS and FAP. The RSTP was decreased in children with IBS and FAP compared with control subjects (P <.002) and was not different in children with FD compared with control subjects. At 30.8 mm Hg, the 5th percentile for the control subjects, the RSTP had a sensitivity rate of 89% and a specificity rate of 83% for IBS and FAP diagnosis.

CONCLUSION

Children with IBS and FAP are characterized by the association of rectal hypersensitivity and abnormal pain referral after rectal distension.

Cortical effects of anticipation and endogenous modulation of visceral pain assessed by functional brain MRI in irritable bowel syndrome patients and healthy controls

Visceral pain processing is abnormal in a majority of irritable bowel syndrome (IBS) patients. Aberrant endogenous nociceptive modulation and anticipation are possible underlying mechanisms investigated in the current study. Twelve IBS patients and 12 matched healthy controls underwent brain fMRI scanning during the following randomised stimuli: sham and painful rectal distensions by barostat without and with simultaneous activation of endogenous descending nociceptive inhibition using ice water immersion of the foot for heterotopic stimulation. Heterotopic stimulation decreased rectal pain scores from 3.7+/-0.2 to 3.1+/-0.3 (mean+/-SE, scale 0-5) in controls (p<0.01), but not significantly in IBS. Controls differed from IBS patients in showing significantly greater activation bilaterally in the anterior insula, SII and putamen during rectal stimulation alone compared to rectal plus heterotopic stimulation. Greater activation during rectal plus heterotopic versus rectal stimulation was seen bilaterally in SI and the right superior temporal gyrus in controls and in the right inferior lobule and bilaterally in the superior temporal gyrus in IBS. Rectal pain scores were similarly low during sham stimulation in both groups, but brain activation patterns differed. In conclusion, IBS patients showed dysfunctional endogenous inhibition of pain and concomitant aberrant activation of brain areas involved in pain processing and integration. Anticipation of rectal pain was associated with different brain activation patterns in IBS involving multiple interoceptive, homeostatic, associative and emotional areas, even though pain scores were similar during sham distension. The aberrant activation of endogenous pain inhibition appears to involve circuitry relating to anticipation as well as pain processing itself.

Effects of serotonin transporter inhibition on gastrointestinal motility and colonic sensitivity in the mouse

Serotonin-selective reuptake transporter (SERT) expression is decreased in animal models of intestinal inflammation and in individuals with inflammatory bowel disease (IBD) or irritable bowel syndrome (IBS), and it is possible that resultant changes in intestinal serotonin signalling contribute to the manifestation of clinical features associated with these disorders. The objective of this investigation was to determine whether inhibition of SERT function leads to changes in gut motility and sensitivity. Mice underwent a 14-day treatment with the SERT inhibitor, paroxetine (20 mg kg(-1)), or vehicle (saline/propylene glycol). Gastrointestinal (GI) transit following charcoal gavage, colonic motility, stool frequency and visceromotor responses to colorectal distension were evaluated. In mice treated with paroxetine, stool output was decreased, upper GI transit was delayed, and colonic sensitivity to a nociceptive stimulus was attenuated. These results demonstrate that reduced SERT function (via pharmacological blockade) significantly alters GI motility and sensitivity in mice, and support the concept that altered SERT expression and function could contribute to symptoms associated with IBS and IBD.

Effect of stress on expression of neuronal nitric oxide synthase in colonic nervous system in rats

AIM: To investigate the effect of stress on the expression of neuronal nitric oxide synthase (nNOS) in colonic nerv-ous system in rats.

METHODS: Thirty male SD rats were randomly divided into control group, stress group and NG-nitro-L-arginine methyl ester (L-NAME) group. The rat model of water immersion-restraint stress (WRS) was established. The expression of nNOS in colonic submucous plexus and myenteric plexus in the rats was examined by immuno-histochemical staining and analyzed by computer image analysis system.

RESULTS: nNOS immune-positive substance was mostly expressed in the neurons of submucous plexus and myenteric plexus. In comparison with that in contr-ol group, the gray value of nNOS positive neurons in submucous plexus and myenteric plexus was signifi-cantly decreased (P = 0.02 or P = 0.005), and the den-sity of nNOS positive neurons was increased markedly (P = 0.04 or P = 0.01) in stress group. Moreover, nNOS expression in mucosal epithelial cells and lamina pro-pria lymphocytes were also observed. In comparison with that in stress group, the gray value of nNOS posi-tive neurons in submucous plexus and myenteric plexus was increased (P = 0.04), and the density of nNOS positive neurons was decreased (P = 0.04 or P = 0.03) in L-NAME group. nNOS expression was not significantly different between the rats of L-NAME and control group (P >0.05).

CONCLUSION: WRS can increase the expression of nNOS in colonic nervous system in rats, which suggests nitric oxide (NO) may play an important role in WRS-induced function disorder of colon.

Biological sensitisation and psychological amplification: gateways to subjective health complaints and somatoform disorders

Subjective health complaints without known physical pathology are common and might develop into somatoform disorders. Normalization of neuroticism and anxiety in patients with duodenal ulcer disease after a relapse-free state is acquired and maintained is an indication that biological factors influence psychological factors. Recent research has shown that psychological and behavioural changes, on the other hand, have the capacity to change the brain. Visceral hyperalgesia is an example of biological sensitisation, but the abnormal sensory perception can be normalised by hypnotherapy. The dual-etiology hypothesis of functional somatic syndromes implies that in some patients with somatoform disorders there is a predominant biological etiology, whereas in others there is a predominant psychological etiology. The theory is supported by recent research, and may result in better handling of patients. Cognitive factors like catastrofising amplifies subjective physical symptoms and emotions effect the perception of them. In preventive health care the following slogans are proposed as antidotes preventing subjective health complaints form developing into somatoform disorders: Do not listen to your body's signals! Do not trust your feelings! Do not trust your thoughts!