Host immune response determines visceral hyperalgesia in a rat model of post-inflammatory irritable bowel syndrome

Identification of potential key genes for colorectal cancer based on bioinformatics analysis

This study aimed to explore key genes as potential biomarkers for colorectal cancer (CRC) diagnosis and prognosis in order to improve their clinical utility. To identify and screen candidate genes involved in CRC carcinogenesis and disease progression, we downloaded the microarray datasets GSE143939, GSE196006, and GSE200427 from the GEO database and applied the GEO2R tool to obtain differentially expressed genes (DEGs) between colorectal cancer tissue samples and normal tissue samples. Differentially expressed genes were analyzed using the DAVID online database for gene ontology and Kyoto encyclopedia of genes and genomes pathway enrichment analyses. Protein-protein interaction network was constructed and related module analysis was performed using STRING and Cytoscape. In total, 241 DEGs were identified, including 127 downregulated and 114 upregulated genes. DEGs enriched functions and pathways included cellular response to chemical stimulus, extracellular region, carbonate dehydratase activity, cell division, spindle, and cell division. The abundant functions and pathways of DEGs included cellular response to chemical stimulus, extracellular region, carbonate dehydratase activity, cell division, spindle, cell adhesion molecule binding, Aldosterone-regulated sodium reabsorption, and Cell cycle-related processes. Fifteen key genes were identified, and bioprocess analyses showed that these genes were mainly enriched in cell cycle, cell division, mitotic spindle, and tubulin binding processes. It was found that CDK1, CEP55, MKI67, and TOP2A may be involved in CRC cancer invasion and recurrence. The pivotal genes identified in this study contribute to our understanding of the molecular and pathogenic mechanisms of CRC carcinogenesis and progression, and provide possible biomarkers for the diagnosis and treatment of CRC.

Peripheral and Spinal Mechanisms Involved in Electro-Acupuncture Therapy for Visceral Hypersensitivity

One of the important characteristic features of clinically significant gastrointestinal disorders is visceral hypersensitivity (VH). Pain sensitization or VH is a big challenge for clinicians and becomes a very thorny work in clinical practices; the therapeutic efficacy for VH results in limited success. A popular second therapy that is being approved for the induction of analgesia and attenuates VH with fewer side effects includes electro-acupuncture (EA). Different peripheral and spinal neurological chemicals, including neurotransmitters, neuropeptides, and cytokines, and different signaling pathways were associated with EA treatment in VH. Despite the higher acceptance of EA, the underlying mechanism still needs to be further explored. In this paper, we review the available literature to find the peripheral and spinal mechanisms involved in EA to relieve VH.

Neuro-Immune Modulation Effects of Sacral Nerve Stimulation for Visceral Hypersensitivity in Rats

Background: Visceral hypersensitivity (VH) is one of the underlying pathophysiologies of irritable bowel syndrome. Mast cell overactivation has been found to be one of the main causes of VH. We investigated the effects and mechanisms of actions of sacral nerve stimulation (SNS) on visceral pain in a rodent model of VH.

Methods: The VH was established by an intrarectal infusion of AA in 10-day-old pups. Rats were chronically implanted with electrodes for SNS and recording electromyogram (EMG) and electrocardiogram. The acute study was performed in 2-randomized sessions with SNS (14 Hz, 330 μs, 40% motor threshold or MT, 30 min) or sham-SNS. Later on, rats were randomized into SNS/sham-SNS groups and a chronic study was performed with 2 h-daily SNS or sham-SNS for 21 days. Visceromotor reflexes were assessed by abdominal EMG and withdrawal reflex (AWR). Colon tissues were collected to study colonic acetylcholine (ACh), the enteric neurons (ChAT, nNOS, and PGP9.5), mast cells activity [Tryptase, prostaglandins E2 (PGE2), and cyclooxygenases-2 (COX2)] and pain markers [nerve growth factor (NGF) and Sub-P].

Key Results: Sacral nerve stimulation significantly improved visceromotor reflexes assessed by the EMG and AWR, compared with sham-SNS. SNS normalized the protein expressions of ChAT and nNOS and regulated mast cells activity by downregulating Tryptase, COX2, and PGE2. Neonatal AA administration upregulated NGF and Sub-P; chronic SNS significantly decreased these pain biomarkers. Concurrently, chronic SNS increased ACh in colon tissues and vagal efferent activity.

Conclusions: Sacral nerve stimulation reduces VH in rats and this ameliorating effect might be attributed to the suppression of mast cell overactivation in the colon tissue via the modulation of autonomic nervous system functions.

Calcium Pyruvate Exerts Beneficial Effects in an Experimental Model of Irritable Bowel Disease Induced by DCA in Rats

Pyruvate is a normal constituent of the body that participates in carbohydrate metabolism and functions as a scavenger of free radicals. Calcium pyruvate monohydrate (CPM) is a more stable derivative that has proved its anti-inflammatory effect in experimental colitis, among other disorders, and that could also be considered a source of calcium. Thus, it would be useful for the treatment of diseases with an inflammatory component and a high prevalence of osteoporosis like the irritable bowel syndrome (IBS). The aim of the present study is to evaluate the effects of CPM in a rat model of chronic post-inflammatory visceral pain induced by deoxycholic acid (DCA) that resembles IBS. Rats were administered DCA for three days intracolonically and then treated daily with CPM (40 and 100 mg/kg) or gabapentin (70 mg/kg) (positive control) by oral gavage for 17 days. The treatments reduced the visceral hypersensitivity measured by response to colorectal distension and referred pain. DCA induced changes in the colonic immune response characterized by increased expression of the cytokine Il-1β and the inducible enzyme Cox-2, which was reduced by the treatments. DCA also decreased the gut expression of the mucins Muc-2 and Muc-3, which was normalized by CPM, whereas gabapentin only increased significantly Muc-3. Moreover, DCA increased the expression of Tlr3, which was decreased to basal levels by all the treatments. However, the serotonin receptor Htr-4, which was also elevated, was not affected by any of the treatments, indicating no effect through this signalling pathway. In conclusion, CPM ameliorated the visceral hypersensitivity and the referred pain caused by DCA, being as effective as the control drug. Furthermore, it improved the immune status of the animals, which could contribute to the visceral analgesia and the regeneration of the intestinal epithelial barrier integrity.

Sustained pain hypersensitivity in the stressed colon: Role of mast cell-derived nerve growth factor-mediated enteric synaptic plasticity

BACKGROUND

Sustained pain hypersensitivity is the hallmark of stressed colon which could be partially explained by central sensitization with synaptic plasticity, the key mechanism of memory. We previously identified that synaptic plasticity of enteric nerve system (ENS) contributed to peripheral pain maintaining in the gut. However, the mechanisms of enteric "memory" formation remain elusive.

METHODS

In this study, rats were exposed to water avoidance stress (WAS) or sham stress (SS), with cromolyn sodium or physiological saline injected intraperitoneally 30 minutes before stress every day. The abdominal withdrawal reflex scores, mesenteric afferent nerve activity, enteric neural c-fos expression, and enteric synaptic plasticity were assessed, and mast cell infiltration and degranulation. Furthermore, colonic mucosal mediators-induced enteric synaptic plasticity and the role of mast cell-derived nerve growth factor (NGF), tryptase, and histamine were investigated via ex vivo longitudinal muscle-myenteric plexus (LMMP) organotypic culture.

KEY RESULTS

It is shown that mast cell stabilizing inhibited WAS-induced visceral hypersensitivity through enhancing visceral pain threshold, decreasing spontaneous and distention-induced mesenteric afferent firing, and downregulating enteric neural activation (c-fos). Importantly, WAS led to evident enteric synaptic plasticity, but decreased by cromolyn. Water avoidance stress-derived mucosal supernatants markedly enhanced the c-fos expression and enteric synaptic plasticity in LMMP tissues, which could be eliminated by mast cell inhibition or NGF neutralization, but not tryptase or histamine blocking.

CONCLUSIONS & INFERENCES

In conclusion, mast cells/NGF pathway may be the key regulator of synaptic plasticity of ENS and participate in the formation of chronic stress-induced sustained visceral hypersensitivity.

Oral probiotic treatment of Lactobacillus rhamnosus Lcr35® prevents visceral hypersensitivity to a colonic inflammation and an acute psychological stress

AIMS

This study evaluated the efficacy of a repeated oral treatment with two active pharmaceutical ingredients (Lcr Lenio^® and Lcr Restituo^® ) derivated from the probiotic bacterial strain Lactobacillus rhamnosus Lcr35^® in two animal models mimicking different features of irritable bowel syndrome (IBS). IBS is characterized by visceral pain associated with alteration of bowel transit. IBS patients present visceral hypersensitivity with peripheral and central origins.

METHODS AND RESULTS

The injection of 2,4,6-trinitrobenzenesulfonic acid (TNBS) into the proximal colon as well as an acute partial restraint stress (PRS) produces colonic hypersensitivity measured in conscious rats by a decrease in pain threshold in response to distal colonic distension. Visceral hypersensitivity was produced by injection of TNBS 7 days before colonic distension or by acute PRS on testing day. Treatments were performed once a day during eight consecutive days.

CONCLUSIONS

This study indicates that an 8-day probiotic treatment (Lcr Lenio and Lcr Restituo) produces an antihypersensitivity activity in both TNBS and PRS visceral pain models. As this probiotic strain attenuates peripherally and centrally induced visceral hypersensitivity in rats, it may be active in treatment of IBS symptoms. An immunomodulatory effect of the probiotics was highlighted in the TNBS model on the IL-23 secretion, suggesting a mechanism of action involving a regulation of the local IL-23/Th17 immune activation.

SIGNIFICANCE AND IMPACT OF THE STUDY

Two formulas of Lcr35^® probiotic strain show very encouraging results for the treatment of IBS patients. Further studies are needed to better understand the role and mechanisms of probiotics on the pathogenesis of IBS.

A novel model for studying ileitis-induced visceral hypersensitivity in goats

BACKGROUND

Visceral hypersensitivity (VH) is a common condition in many gastrointestinal disorders such as inflammatory bowel diseases (IBDs) in human and animals. Most studies often induce Crohn's disease/colitis to investigate VH in small experimental animals. Although farm animals commonly suffer from IBDs, their VH has not been investigated so far. Because goats can suffer from Johne's disease, a naturally occurring Crohn's-like disease, they may be suitable to be used for studying the mechanism underlying VH in common intestinal disorders of large animals. In the present study, 60 healthy goats of either sex were equally divided into a 2, 4, 6-trinitrobenzenesulfonic acid (TNBS) group and saline group. A volume of 1.2 ml of TNBS-ethanol solution (30 mg TNBS in 40 % ethanol) or an equal volume of isotonic saline was injected into the wall of the terminal ileum through laparotomy. The severity of the developing ileitis was determined according to macro- and microscopic pathologic scores and the levels of myeloperoxidase, interleukin-1β, interleukin-6 and tumor necrosis factor-α, and VH was evaluated with visceromotor responses (VMR) to colorectal distension on days 3, 7, 14, 21 and 28. VMRs were assessed with a continuous ramp distention mode with 6 s for each pressure (20, 40, 60, 80 and 100 mmHg).

RESULTS

Compared to the saline group, the TNBS-treated goats showed apparent transmural pathological changes and a significant increase (P < 0.05) in macroscopic and microscopic change scores, and levels of myeloperoxidase, interleukin-1β, interleukin-6 and tumor necrosis factor-α in the ileum, and VMR to colorectal distension. The goats exhibited apparent ileitis at days 3 to 21, and VH at days 7 to 28 following TNBS treatment.

CONCLUSION

This experiment successfully established a reproducible ileitis and VH with administration of TNBS-ethanol solution in the ileal wall of goats. This model is useful for studying the pathogenesis of the IBD and the mechanism underlying VH, and for evaluating the efficacy of new therapeutic regimens.

Evidence that independent gut-to-brain and brain-to-gut pathways operate in the irritable bowel syndrome and functional dyspepsia: a 1-year population-based prospective study

BACKGROUND

Traditionally, functional gastrointestinal disorders (FGIDs) are conceptualised as originating in the brain via stress pathways (brain-to-gut). It is uncertain how many with irritable bowel syndrome (IBS) and functional dyspepsia (FD) have a gut origin of symptoms (gut-to-brain pathway).

AIMS

To determine if there is a distinct brain-to-gut FGID (where psychological symptoms begin first) and separately a distinct gut-to-brain FGID (where gut symptoms start first).

METHODS

A prospective random population sample from Newcastle, Australia who responded to a validated survey in 2012 and completed a 1-year follow-up survey (n = 1900). The surveys contained questions on Rome III IBS and FD and the Hospital Anxiety and Depression Scale.

RESULTS

We found that higher levels of anxiety and depression at baseline were significant predictors of developing IBS (OR = 1.31; 95% CI 1.06-1.61, P = 0.01; OR = 1.54; 95% CI 1.29-1.83, P < 0.001) and FD (OR = 1.28; 95% CI 1.05-1.55, P = 0.01; OR = 1.55, 95% CI 1.32-1.83, P < 0.001), respectively, at the 1-year follow-up. Among those people who did not have elevated levels of anxiety and depression at baseline, subjects at baseline with documented IBS (mean difference 0.34; 95% CI 0.13-0.55, P = 0.002; 0.81; 95% CI 0.47-1.15, P < 0.001) and FD (0.38; 95% CI 0.14-0.63, P = 0.002; 0.92; 95% CI 0.57-1.27, P < 0.001), reported significantly higher levels of anxiety and depression at the 1-year follow-up. We calculated in one-third of individuals a mood disorder precedes FGID but in two-thirds an FGID precedes the mood disorder.

CONCLUSION

While brain-gut pathways are bidirectional, a major subset begin with gut symptoms first and only then psychological distress develops, implicating primary gut mechanisms as drivers of the gut and extra-intestinal features in many cases.

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.

Age, Gender and Women's Health and the Patient

Patients with functional gastrointestinal disorders (FGIDs) often experience distress, reduced quality of life, a perceived lack of validation, and an unsatisfactory experience with health care providers. A health care provider can provide the patient with a framework in which to understand and legitimize their symptoms, remove self-doubt or blame, and identify factors that contribute to symptoms that the patient can influence or control. This framework is implemented with the consideration of important factors that impact FGIDs, such as gender, age, society, and the patient's perspective. Although the majority of FGIDs, including globus, rumination syndrome, IBS, bloating, constipation, functional abdominal pain, sphincter of Oddi dyskinesia, pelvic floor dysfunction, and extra-intestinal manifestations, are more prevalent in women than men, functional chest pain, dyspepsia, vomiting, and anorectal pain do not appear to vary by gender. Studies suggest sex differences in somatic but not visceral pain perception, motility, and central processing of visceral pain; although further research is required in autonomic nervous system dysfunction, genetics and immunologic/microbiome. Gender differences in response to psychological treatments, antidepressants, fiber, probiotics, and anticholinergics have not been adequately studied. However, a greater clinical response to 5-HT3 antagonists but not 5-HT4 agonists has been reported in women compared with men.

Associations among gut permeability, inflammatory markers, and symptoms in patients with irritable bowel syndrome

BACKGROUND

Alterations in gastrointestinal (GI) permeability and immune measures are present in some patients with irritable bowel syndrome (IBS) but the relationship to symptoms is poorly defined. In adults with IBS, we compared permeability, unstimulated peripheral blood monocyte (PBMC) interleukin-10 (IL-10) levels, IBS life interference, and GI and psychological distress symptoms.

METHODS

In 88 women and 18 men with IBS, GI permeability was quantitated as percent recovery of urinary sucrose and the lactulose/mannitol (L/M) ratio. IL-10 was measured in supernatants from 72-h incubated, unstimulated PBMCs. Participants completed a 4-week daily diary recording IBS life interference on daily activities and work, IBS symptoms, and psychological distress symptoms. They also completed the Brief Symptom Inventory.

RESULTS

The L/M ratio but not percent sucrose recovery was significantly correlated with IBS interference with activities and work and retrospectively measured anxiety and depression. Unstimulated PBMC production of IL-10 correlated significantly with IBS interference with daily work, IBS symptom score, and abdominal pain. We identified a subgroup of IBS subjects with higher IL-10 and/or higher L/M ratio who had substantially higher IBS interference and IBS symptom scores.

CONCLUSIONS

Our findings suggest a distinct subgroup of IBS patients with alterations in gut barrier function. This subgroup is characterized by increased GI permeability and/or increased PBMC production of IL-10. These physiologic alterations reflect more severe IBS as measured by interference of IBS with daily activities and daily IBS symptoms.

The effect of chemically induced colitis, psychological stress and their combination on visceral pain in female Wistar rats

Visceral sensitivity is of pathophysiological importance in abdominal pain disorders and can be modulated by inflammation and stress. However, it is unclear whether inflammation and stress alter visceral perception independently of each other or in conjunction through neuroendocrine interactions. Therefore, we compared the short- and long-term effects of experimental colitis and water avoidance stress (WAS), alone or in combination, on visceral sensitivity in female Wistar rats. Colitis was induced by trinitrobenzene sulfonic acid (TNBS) and colonoscopically confirmed. During WAS, rats were placed on a platform surrounded by water for 1 h. Visceral sensitivity was assessed by quantifying the visceromotor responses (VMRs) to colorectal distension. Activation of the hypothalamic-pituitary-adrenal axis was determined by measuring serum corticosterone in a separate protocol. TNBS instillation resulted in overt colitis, associated with significant visceral hypersensitivity during the acute inflammatory phase (3 days post-TNBS; n = 8/group); after colitis had subsided (28 days post-TNBS), hypersensitivity was resolved (n = 4-8/group). Single WAS was associated with increased VMRs of a magnitude comparable to acute TNBS-induced hypersensitivity (n = 8/group). However, after repetitive WAS no significant hypersensitivity was present (n = 8/group). No additive effect of colitis and stress was seen on visceral pain perception (n = 6-8/group). Corticosterone levels were only increased in acute TNBS-colitis, acute WAS and their combination. To conclude, both colitis and stress successfully induced short-term visceral hypersensitivity and activated the hypothalamic-pituitary-adrenal axis, but long-term effects were absent. In addition, our current findings do not support an additive effect of colitis and stress on visceral sensitivity in female Wistar rats.

A nationwide population cohort study: irritable bowel syndrome is a risk factor of osteoporosis

BACKGROUND

The goal of the study is to determine the relationship between irritable bowel syndrome (IBS) and osteoporosis in Taiwan.

MATERIALS AND METHODS

We collected data from the National Health Insurance (NHI) program in Taiwan. The sample in this study consisted of 31,892 patients enrolled from 2000 to 2009 and diagnosed by the International Classification of Diseases, 9th Revision, Clinical Modification (ICD-9-CM). We divided the sample into 2 cohorts based on whether they had IBS, and formed subgroups based on age, sex, enrolment year, and enrolment month.

RESULTS

Age and gender did not differ statistically among the 2 cohorts. Results show that IBS is more correlated with urbanization and the occupation of business. The IBS cohort had a higher incidence of osteoporosis than the non-IBS cohort (6.90 vs 4.15 per 1000 person-years; HR=1.65, 955 CI=1.54-1.77). Female patients aged 40-59years had the highest risk of developing osteoporosis (HR=4.42, 95% CI=3.37-5.79 in the IBS cohort; HR=4.41, 95% CI=3.67-5.29 in the non-IBS cohort, respectively). In IBS patients less than 40years of age, female patients had a significant 2.18-fold greater risk of developing osteoporosis than male patients (HR=2.18, 95% CI=1.09-4.38).

CONCLUSIONS

IBS is a risk factor for osteoporosis in Taiwan.