Pain and inflammatory bowel disease

The Anti-Inflammatory and Pain-Relieving Effects of AR170, an Adenosine A3 Receptor Agonist, in a Rat Model of Colitis

The pharmacological activation of A₃ receptors has shown potential usefulness in the management of bowel inflammation. However, the role of these receptors in the control of visceral hypersensitivity in the presence of intestinal inflammation has not been investigated. The effects of AR170, a potent and selective A₃ receptor agonist, and dexamethasone (DEX) were tested in rats with 2,4-dinitrobenzene sulfonic acid (DNBS)-induced colitis to assess their tissue inflammatory parameters. The animals received AR170, DEX, or a vehicle intraperitoneally for 6 days, starting 1 day before the induction of colitis. Visceral pain was assessed by recording the abdominal responses to colorectal distension in animals with colitis. Colitis was associated with a decrease in body weight and an increase in spleen weight. The macroscopic damage score and tissue tumor necrosis factor (TNF), interleukin 1β (IL-1β), and myeloperoxidase (MPO) levels were also enhanced. AR170, but not DEX, improved body weight. Both drugs counteracted the increase in spleen weight, ameliorated macroscopic colonic damage, and decreased TNF, IL-1β, and MPO tissue levels. The enhanced visceromotor response (VMR) in rats with colitis was decreased via AR170 administration. In rats with colitis, AR170 counteracted colonic inflammatory cell infiltration and decreased pro-inflammatory cytokine levels, thereby relieving visceral hypersensitivity.

Pain matrix shift in the rat brain following persistent colonic inflammation revealed by voxel-based statistical analysis

Inflammatory bowel disease (IBD), mainly comprising Crohn’s disease and ulcerative colitis, is characterized by chronic inflammation in the digestive tract. Approximately 60% of the patients experience abdominal pain during acute IBD episodes, which severely impairs their quality of life. Both peripheral and central mechanisms are thought to be involved in such abdominal pain in IBD. Although much attention has been paid to peripheral mechanisms of abdominal pain in IBD pathophysiology, the involvement of supraspinal mechanisms remains poorly understood. To address this issue, we investigated regional brain activity in response to colorectal distension in normal and IBD model rats using voxel-based statistical analysis of 2-deoxy-2-[18F]fluoro-_D-glucose positron emission tomography imaging. The rat IBD model was generated by colorectal administration of 2,4,6-trinitrobenzene sulfonic acid, a chemical compound widely used to generate colitis. Tissue damage and inflammation were induced and dynamically changed with time after 2,4,6-trinitrobenzene sulfonic acid injection, while colorectal distension-induced visceromotor response showed corresponding temporal changes. We found that characteristic brain activations were observed in response to visceral innocuous and noxious colorectal distension and supraspinal nociception shared some physiological sensory pathway. Moreover, widespread brain regions were activated, and the functional coupling between the central medial thalamic nucleus and anterior cingulate cortex was enhanced after noxious colorectal distension in IBD model of rats. Increased brain activity in the anterior insular cortex and anterior cingulate cortex was positively correlated with noxious colorectal distension-induced pain severity in normal and IBD rats, respectively. These findings suggest that the pain matrix was shifted following persistent colonic inflammation, and thalamocortical sensitization in the pathway from the central medial thalamic nucleus to anterior cingulate cortex might be a central mechanism of the visceral hyperalgesia in IBD pathophysiology.

Transient receptor potential ankyrin 1 contributes to somatic pain hypersensitivity in experimental colitis

Pain evoked by visceral inflammation is often ‘referred’ to the somatic level. Transient receptor potential ankyrin 1 (TRPA1) has been reported to contribute to visceral pain-like behavior in dextran sulfate sodium (DSS)-evoked colitis. However, the role of TRPA1 in somatic component of hypersensitivity due to visceral inflammation is unknown. The present study investigated the role of TRPA1 in colitis-evoked mechanical hypersensitivity at the somatic level. Colitis was induced in mice by adding DSS to drinking water for one week. Control and DSS-treated mice were tested for various parameters of colitis as well as mechanical pain sensitivity in abdominal and facial regions. DSS treatment caused mechanical hypersensitivity in the abdominal and facial skin. Pharmacological blockade or genetic deletion of TRPA1 prevented the colitis-associated mechanical hypersensitivity in the abdominal and facial skin areas although the severity of colitis remained unaltered. DSS treatment increased expression of TRPA1 mRNA in cultured dorsal root ganglion (DRG) neurons, but not trigeminal ganglion neurons, and selectively enhanced currents evoked by the TRPA1 agonist, allyl isothiocyanate, in cultured DRG neurons. Our findings indicate that the TRPA1 channel contributes to colitis-associated mechanical hypersensitivity in somatic tissues, an effect associated with upregulation of TRPA1 expression and responsiveness in DRG nociceptors.

Feline Neuropathic Pain

Neuropathic pain represents the extreme in maladaptive pain processing. In itself, it is a disease in which pain has become exaggerated in some combination of scope, severity, character, field, duration, and spontaneity. It is almost certainly an underappreciated, underdiagnosed cause of possible significant patient morbidity in cats. This article explores the basic mechanisms, recognition, known and suspect syndromes, and prospective treatment of feline maladaptive and neuropathic pain.

Association Between Vulvovaginal Discomfort and Activity of Inflammatory Bowel Diseases

BACKGROUND & AIMS

Inflammatory bowel diseases (IBD) affect 200-400 people per 100,000 in the United States, about half of whom are women. We aimed to define the prevalence of vulvovaginal symptoms and association with IBD activity in a large cohort of women.

METHODS

Women more than 18 years old with IBD (1250) completed an online survey querying the presence and severity of vulvar or vaginal itch, burn, or irritation, vaginal discharge or dryness, and vulvovaginal pain. The survey collected information on demographic features and IBD activity (categorized using the Manitoba index). Women with and without symptoms were compared using bivariate analyses. Logistic regression evaluated associations between IBD severity and vulvovaginal symptoms, adjusted for diagnosis, menopause, smoking, depression, and use of medications to treat IBD.

RESULTS

A total of 512 (41%) women reported at least 1 moderate-severe vulvovaginal symptom. All vulvovaginal symptoms except vaginal dryness were more common in women with active IBD. In a multivariate model controlled for menopause, smoking, t-score from the PROMIS depression instrument, and use of IBD medications, women with constant or frequent active IBD, based on Manitoba index scores, had increased odds for moderate-severe vulvovaginal symptoms (odds ratio, 1.68; 95% CI, 1.22-2.32) compared to women in remission. Vulvovaginal discomfort frequently or always decreased interest in sex (n=336; 28%) or ability to have sex (n=207; 16%).

CONCLUSIONS

In an online survey of 1250 women, we found that women with more active IBD have increased prevalence of vulvovaginal discomfort, compared to women in remission. These symptoms affect sexual health.

Developing a better biopsychosocial understanding of pain in inflammatory bowel disease: a cross-sectional study

OBJECTIVE

Pain is frequently reported by patients with inflammatory bowel disease (IBD). Pain in IBD is not fully explained by disease activity or other clinical findings, and a recent systematic review suggested that psychosocial factors have an important role in IBD-pain. The aim of this study was to investigate psychosocial factors associated with pain in IBD.

METHODS

297 adults (>16 years) with IBD were recruited from outpatient clinics (n = 114) and online (n = 183). Participants completed validated questionnaires assessing pain and potential emotional, cognitive and behavioural correlates. Socio-demographic and clinical factors including disease activity were also recorded.

RESULTS

243 (81.8%) of participants reported pain. Of these 243, mean age was 36 years; 153 (63%) had Crohn's disease, 90 (37%) had ulcerative colitis, and 165 (67.9%) were female. 62.6% reported mild, 31.6% moderate and 5.8% severe pain. 40.3% of participants with pain met established criteria for chronic pain and 18.5% reported opioid use. Female gender, smoking, surgery and steroid use were associated with greater pain severity. Psychosocial factors associated with pain-related interference included depression, catastrophising, fear avoidance, lower self-efficacy and worse mental well-being. Regression models explained 45.6% of the variance in pain severity and 49.7% of pain interference. Psychosocial factors explained 9.5% and 24% of this variance respectively when controlling for demographic and clinical variables.

CONCLUSIONS

Pain in IBD is significantly associated with cognitive and behavioural factors as well as low mood. This study contributes to a biopsychosocial understanding of pain in IBD and identifies important targets for future interventions.

Modelling symptoms to suicide risk in individuals with inflammatory bowel disease

Given that suicidal behaviour is a pressing concern in inflammatory bowel disease populations, this study sought to model the sequence of variables that lead to its development. Participants (n = 282) completed online self-report questionnaires regarding predictors of suicidal behaviour. A cross-sectional model of the progression from symptoms to suicide risk revealed that biomedical variables were significantly associated with psychosocial predictors of suicidal behaviour, which were significantly related to theory-driven predictors of suicidal behaviour, which were ultimately associated with suicide risk. Evidently, interventions need to target distal predictors of suicidal behaviour to mitigate harmful downstream effects.

Epithelial-Neuronal Communication in the Colon: Implications for Visceral Pain

Visceral hypersensitivity and pain result, at least in part, from increased excitability of primary afferents that innervate the colon. In addition to intrinsic changes in these neurons, emerging evidence indicates that changes in lining epithelial cells may also contribute to increased excitability. Here we review recent studies on how colon epithelial cells communicate directly with colon afferents. Specifically, anatomical studies revealed specialized synaptic connections between epithelial cells and nerve fibers and studies using optogenetic activation of the epithelium showed initiation of pain-like responses. We review the possible mechanisms of epithelial-neuronal communication and provide an overview of the possible neurotransmitters and receptors involved. Understanding the biology of this interface and how it changes in pathological conditions may provide new treatments for visceral pain conditions.

CD3+ T cells are critical for the resolution of comorbid inflammatory pain and depression-like behavior

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T cells are necessary for resolution of CFA-induced mechanical allodynia and spontaneous pain.

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T cells are required for the resolution of inflammation-induced depression-like behavior.

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T cells did not contribute to onset or severity of indicators of pain and depression-like behavior.

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T cells did not affect cytokine expression in the paw, spinal cord and brain.

Background

Chronic pain and depression often co-occur. The mechanisms underlying this comorbidity are incompletely understood. Here, we investigated the role of CD3⁺ T cells in an inflammatory model of comorbid persistent mechanical allodynia, spontaneous pain, and depression-like behavior in mice.

Methods

C57Bl/6 wt and Rag2^−/− mice were compared in their response to intraplantar administration of complete Freund’s adjuvant (CFA). Mechanical allodynia, spontaneous pain and depression-like behavior were assessed by von Frey, conditioned place preference and forced swim test respectively.

Results

Resolution of mechanical allodynia, spontaneous pain, and depression-like behavior was markedly delayed in Rag2^−/− mice that are devoid of adaptive immune cells. Reconstitution of Rag2^−/− mice with CD3⁺ T cells from WT mice before CFA injection normalized the resolution of indicators of pain and depression-like behavior. T cells did not contribute to onset or severity of indicators of pain and depression-like behavior. The lack of T cells did not affect cytokine expression in the paw, spinal cord and brain, indicating that the delayed resolution was not resulting from prolonged (neuro)inflammation.

Conclusions

Our findings show that T cells are critical for the natural resolution of mechanical allodynia, spontaneous pain, and depression-like behavior after an inflammatory challenge. Dysregulation of this T cell-mediated resolution pathway could contribute to the comorbidity of chronic pain and depression.

Significance

Chronic pain and depression are frequently associated with signs of inflammation. However, general immunosuppression is not sufficient to resolve comorbid pain and depression. Here we demonstrate that T cells are required for resolution of comorbid persistent mechanical allodynia, spontaneous pain, and depression in a model of peripheral inflammation, indicating the immune system can contribute to both onset and resolution of these comorbidities. Enhancing pro-resolution effects of T cells may have a major impact to treat patients with comorbid persistent pain and depression.

Happiness in dermatology: a holistic evaluation of the mental burden of skin diseases

BACKGROUND

According to the World Health Organization, mental health is a state of well-being and not merely the absence of disease. However, studies exploring subjective well-being in patients with skin diseases are very rare.

OBJECTIVES

To assess subjective well-being, i.e. 'happiness', in patients with different skin diseases and to compare them to other patient groups and healthy controls.

METHODS

A cross-sectional study was conducted from 12/2017 to 04/2019. Patients receiving in- or outpatient care for psoriasis, atopic eczema, nummular eczema, mastocytosis, skin cancer (malignant melanoma and keratinocyte carcinoma), human immunodeficiency virus (HIV) or chronic inflammatory bowel diseases (Crohn's disease and ulcerative colitis) were recruited at two hospitals in Bavaria, Germany. Healthy individuals living in or near Munich served as a control group. All participants filled in a questionnaire assessing happiness, measured as positive affect (PA), negative affect and satisfaction with life (SWL; together representing subjective well-being) and a heuristic evaluation of one's own happiness.

RESULTS

Data from 229 dermatologic patients (53.3 ± 18.5 years, 48% women), 49 patients with inflammatory bowel diseases (48.9 ± 18.7 years, 43% women), 49 patients with HIV (46 ± 10.1 years, 10% women) and 106 healthy controls (38.4 ± 13.4 years, 49% women) were analysed. Compared to the controls, dermatologic patients reported lower heuristic happiness (P = 0.023) and PA (P = 0.001) but higher SWL (P = 0.043). Patients with psoriasis and atopic eczema reported the lowest happiness, as they reported significantly lower PA (P = 0.032 and P < 0.001) and heuristic happiness (P = 0.002 and P = 0.015) than the control group. Patients with skin cancer reported higher SWL than the control group (P = 0.003). Dermatologic patients reported lower happiness than patients with HIV but reported greater happiness than patients with IBD.

CONCLUSIONS

Dermatologic patients experience lower levels of happiness, especially PA, compared to healthy controls. As PA is linked to desirable health outcomes, targeting PA could be a promising holistic approach for the treatment of skin diseases.

Gastrointestinal pain

Gastrointestinal (GI) pain - a form of visceral pain - is common in some disorders, such as irritable bowel syndrome, Crohn's disease and pancreatitis. However, identifying the cause of GI pain frequently represents a diagnostic challenge as the clinical presentation is often blurred by concomitant autonomic and somatic symptoms. In addition, GI pain can be nociceptive, neuropathic and associated with cancer, but in many cases multiple aetiologies coexist in an individual patient. Mechanisms of GI pain are complex and include both peripheral and central sensitization and the involvement of the autonomic nervous system, which has a role in generating the symptoms that frequently accompany pain. Treatment of GI pain depends on the precise type of pain and the primary disorder in the patient but can include, for example, pharmacological therapy, cognitive behavioural therapies, invasive surgical procedures, endoscopic procedures and lifestyle alterations. Owing to the major differences between organ involvement, disease mechanisms and individual factors, treatment always needs to be personalized and some data suggest that phenotyping and subsequent individual management of GI pain might be options in the future.

Biopsychosocial Correlates of Presence and Intensity of Pain in Adolescents With Inflammatory Bowel Disease

Background: There is growing consensus that pain in pediatric inflammatory bowel disease (IBD) is not fully explained by disease-related processes. However, previous studies have largely measured individual biological, psychological, or social risk factors for pain in isolation. Further, not all youth with IBD presenting to clinic will report presence of pain, and those who do vary in their reports of pain intensity. This study therefore extends prior research by determining biopsychosocial correlates of both presence and intensity of pain in adolescents with IBD, in order to inform targeted pain management intervention approaches. Methods: Adolescents with IBD followed at SickKids, Toronto, and their parents were consecutively enrolled from outpatient clinic. IBD characteristics (diagnosis, time since diagnosis, patient-reported disease activity) were collected. Adolescents reported on current pain (NRS-10), internalizing symptoms (Strengths and Difficulties Questionnaire), and pain catastrophizing (Pain Catastrophizing Scale-Child). Parents reported on protective responses to child pain (Adult Responses to Child Pain) and pain catastrophizing (Pain Catastrophizing Scale-Child). Hurdle models were conducted to examine predictors of presence and intensity of pain in the same model. Biological (patient-reported disease activity, IBD diagnosis subtype, illness duration), psychological (internalizing symptoms, pain catastrophizing), and social (parent pain catastrophizing, parent protective responses) factors were entered as predictors, adjusting for age and sex. Results: Participants included 100 adolescents (12-18; Mean = 15 years) with IBD (60% Crohn's Disease, 40% Ulcerative Colitis or IBD-unclassified) and 76 parents. The majority of the sample was in clinical remission or reported minimal symptoms. Half of participants reported no current pain; for those reporting pain, intensity ranged 1-7 (M = 3.43, SD = 1.98). Disease activity (OR = 53.91, p < 0.001) and adolescent internalizing symptoms (OR = 7.62, p = 0.03) were significant predictors of presence of pain. Disease activity (RR = 1.37, p = 0.03) and parent protective responses (RR = 1.45, p = 0.02) were significant predictors of intensity of pain. Conclusions: Results suggest that the experience of pain in pediatric IBD is biopsychosocially determined. Patient-reported disease activity and internalizing symptoms predicted presence of pain, while disease activity and parent protective responses predicted intensity of pain. While medical intervention in pediatric IBD is focused on disease management, results suggest that depression/anxiety symptoms as well as parent protective responses may be important targets of pain management interventions in pediatric IBD.

Pain Severity and Vitamin D Deficiency in IBD Patients

Background: Pain and vitamin D deficiency are common in inflammatory bowel disease (IBD). Disease activity, fatigue, frequent relapses, prior surgery and psychological factors all seem to influence the experience of pain in IBD. Vitamin D deficiency has been associated with muscle and skeletal pain. This study aimed to determine whether there is an association between vitamin D deficiency and severity of pain in patients with IBD, and to investigate the influence of other socio-demographic and psychological variables on the experience of pain. Methods: Patients with IBD were recruited from nine hospitals in Norway in a multicenter cross-sectional study. The Brief Pain Inventory (BPI) questionnaire was used to measure pain. Disease activity was assessed using clinical disease activity indices, C-reactive protein (CRP) and fecal calprotectin. Regression models were fitted to explore a possible association between 25-hydroxyvitamin D and pain severity. Results: Of 407 patients included in the analyses, 229 (56%) had Crohn’s disease (CD) and 178 (44%) had ulcerative colitis (UC). Vitamin D deficiency was present in half (203/407) of patients. Presence of pain was reported by 76% (309/407). More severe pain was associated with female gender and increased disease activity scores, but not with increased CRP or fecal calprotectin. In CD, patients without prior intra-abdominal surgery reported more severe pain. In multivariate analyses, there was no association between 25-hydroxyvitamin D and pain severity. Conclusions: In this study, no significant association between pain severity and vitamin D deficiency was revealed in patients with IBD.

Influence of Acrylamide Administration on the Neurochemical Characteristics of Enteric Nervous System (ENS) Neurons in the Porcine Duodenum

The digestive tract, especially the small intestine, is one of the main routes of acrylamide absorption and is therefore highly exposed to the toxic effect of acrylamide contained in food. The aim of this experiment was to elucidate the effect of low (tolerable daily intake—TDI) and high (ten times higher than TDI) doses of acrylamide on the neurochemical phenotype of duodenal enteric nervous system (ENS) neurons using the pig as an animal model. The experiment was performed on 15 immature gilts of the Danish Landrace assigned to three experimental groups: control (C) group—pigs administered empty gelatine capsules, low dose (LD) group—pigs administered capsules with acrylamide at the TDI dose (0.5 μg/kg body weight (b.w.)/day), and the high dose (HD) group—pigs administered capsules with acrylamide at a ten times higher dose than the TDI (5 μg/kg b.w./day) with a morning feeding for 4 weeks. Administration of acrylamide, even in a low (TDI) dose, led to an increase in the percentage of enteric neurons immunoreactive to substance P (SP), calcitonin gene-related peptide (CGRP), galanin (GAL), neuronal nitric oxide synthase (nNOS), and vesicular acetylcholine transporter (VACHT) in the porcine duodenum. The severity of the changes clearly depended on the dose of acrylamide and the examined plexus. The obtained results suggest the participation of these neuroactive substances in acrylamide-inducted plasticity and the protection of ENS neurons, which may be an important line of defence from the harmful action of acrylamide.

Gastrointestinal hypoalgesia in inflammatory bowel disease

Background:

Pain perception is critical for detection of noxious bodily insults. Gastrointestinal hypoalgesia in inflammatory bowel disease (IBD) is a poorly understood phenomenon previously linked to poor patient outcomes. We aimed to evaluate the risk factors associated with this condition and to discern characteristics that might differentiate these patients from pain-free quiescent counterparts.

Methods:

We performed a retrospective analysis using an IBD natural history registry based in a single tertiary care referral center. We compared demographic and clinical features in 3 patient cohorts defined using data from simultaneous pain surveys and ileocolonoscopy: a) active IBD without pain (hypoalgesic IBD); b) active IBD with pain; and c) inactive IBD without pain.

Results:

One hundred fifty-three IBD patients had active disease and 43 (28.1%) exhibited hypoalgesia. Hypoalgesic IBD patients were more likely to develop non-perianal fistulae (P=0.03). On logistic regression analysis, hypoalgesic IBD was independently associated with male sex, advancing age and mesalamine use, and inversely associated with anxious/depressed state and opiate use. Hypoalgesic IBD patients were demographically and clinically similar to the pain-free quiescent IBD cohort (n=59). Platelet count and C-reactive protein were more likely to be pathologically elevated in hypoalgesic IBD (P=0.03), though >25% did not exhibit elevated inflammatory markers.

Conclusions:

Hypoalgesia is common in IBD, particularly in male and older individuals, and is associated with an increased incidence of fistulae and corticosteroid use. Novel noninvasive diagnostic tools are needed to screen for this population, as inflammatory markers are not always elevated.

Opioid Use Is Associated With Higher Health Care Costs and Emergency Encounters in Inflammatory Bowel Disease

BACKGROUND

We aimed to examine opioid use among adult patients with inflammatory bowel disease (IBD) in the United States and the impact of extended opioid use on emergency health care services and health care costs among patients.

METHODS

We conducted a retrospective cohort study using medical claims data from the Truven Health MarketScan research databases, consisting of patients across the United States with employer-based health insurance. Subjects with IBD were identified in 2009. The occurrence of an emergent encounter in 2010 and health care costs were assessed.

RESULTS

There were 76,171 subjects with 35,993 emergent encounters among the study population, for an overall rate of 0.47 per patient-year. However, these encounters were confined to 6.9% of patients overall. The median total charges per patient in 2010 were $5372. Extended opioid use in 2009 was associated with a higher odds of an emergent encounter in 2010 (odds ratio [OR], 1.82; 95% confidence interval [CI], 1.67-1.98), higher incidence rate of emergent encounters (incidence rate ratio, 2.07; 95% CI, 1.91-2.24), and higher odds of being in the top quartile of cost in 2010 (OR, 1.90; 95% CI, 1.79-2.02). Depression was a strong predictor of extended opioid use (OR, 2.64; 95% CI, 2.49-2.81; P < 0.001).

CONCLUSIONS

Extended opioid use among patients with IBD is an important predictor of emergent encounters and is associated with higher total health care costs. Psychosocial comorbidities are significant predictors of extended opioid use in patients with IBD.

'It's about willpower in the end. You've got to keep going': a qualitative study exploring the experience of pain in inflammatory bowel disease

BACKGROUND

Pain is a widely experienced symptom of inflammatory bowel disease (IBD), which has significant psychological and functional impacts on patients. Understanding the aetiology and management of chronic pain is a poorly understood area of IBD research. This qualitative study aimed to explore the experiences of individuals with IBD and pain, the pain management strategies they use and any needs for future pain management interventions.

METHODS

In all, 14 individuals with IBD were purposively recruited and interviewed (face-to-face or telephone) using a topic guide. Interviews were transcribed and analysed using inductive thematic analysis.

RESULTS

Themes identified were 'vicious cycles', 'findings solutions' and 'attitudes'. The experience and impact of pain were rarely viewed in isolation, but rather within the context of a cycle of IBD symptoms. Other 'vicious cycles' identified included anxiety, avoidance and inactivity, and poor understanding and communication. Pain management included short- and long-term strategies. Searching for a solution for pain had an emotional impact on individuals. There were contrasting attitudes from participants, including defeat, tolerance and acceptance.

CONCLUSION

This study provides an understanding of the experience of pain in IBD. The interaction of pain with accompanying IBD symptoms has an emotional and physical impact on individuals, and creates a barrier to adequate assessment, understanding and treatment of pain. Patients rely on their own experiences, and a trial and error approach to apply helpful strategies. Adjuvant behavioural therapies may be beneficial for patients experiencing pain and psychological distress, and to facilitate self-management.

The Role of Distress and Pain Catastrophizing on the Health-related Quality of Life of Children With Inflammatory Bowel Disease

OBJECTIVES

Inflammatory bowel disease (IBD) can be particularly challenging during the pediatric age with a relevant impact on patient's health-related quality of life (HRQoL). Disease activity accounts for only a small part of the variability in HRQoL, and psychological factors can play a significant role. We aimed to evaluate the impact of patient's distress and pain catastrophizing on children and adolescents with IBD.

METHODS

We prospectively recruited children aged 8 to 18 with IBD and recorded demographic and disease characteristics. Patients answered questionnaires on HRQoL (IMPACT III), distress (distress thermometer [DT]), and pain catastrophizing (Pain Catastrophizing Scale-Children [PCS-C]). Univariate and multivariate regression models analysis were used to evaluate correlations between patients' characteristics, disease activity, distress, pain catastrophizing, and HRQoL.

RESULTS

Seventy-one patients were enrolled (median age 13.6, 49.3% Crohn disease, 50.7% ulcerative colitis). Median HRQoL, DT, and PCS-C scores were 78.6 (interquartile range 68.0-87.1), 3.0 (1.0-5.0), and 12.0 (4.0-23.0), respectively. Patient's distress and pain catastrophizing levels significantly correlated with HRQoL. Pain catastrophizing had the strongest impact on HRQoL (Spearman correlation coefficient, ρ = 0.73), followed by distress (ρ = 0.67), and ulcerative colitis severity (ρ = 0.67). The DT and the PCS-C scores were significantly associated (ρ = 0.46).

CONCLUSIONS

Distress and pain catastrophizing have a significative impact on HRQoL in young patients with IBD. Physicians should recognize the role of these psychological factors and consider cognitive-behavioral therapy to optimize the patient's health.

Association of Psoriasis With Inflammatory Bowel Disease: A Systematic Review and Meta-analysis

Importance

Patients with psoriasis may experience comorbidities involving cardiovascular diseases, chronic kidney disease, uveitis, psychiatric disturbances, and metabolic syndrome. However, the association between psoriasis and inflammatory bowel disease (IBD) has been largely unclear.

Objective

To investigate the association of psoriasis with IBD.

Data Sources

For this systematic review and meta-analysis, MEDLINE, Embase, and the Cochrane Central Register of Controlled Trials were searched for relevant studies from inception to January 17, 2018.

Study Selection

Case-control, cross-sectional, or cohort studies that examined either the odds or risk of IBD in patients with psoriasis were included. No geographic or language limitations were used in the search.

Data Extraction and Synthesis

The PRISMA and MOOSE guidelines were followed for data extraction. The Newcastle-Ottawa Scale was used to evaluate the risk of bias of included studies. Crohn disease and ulcerative colitis were analyzed separately and random-effects model meta-analysis was conducted. A subgroup analysis was performed on psoriatic arthritis.

Main Outcomes and Measures

The risk and odds of IBD, Crohn disease, and ulcerative colitis in patients with psoriasis.

Results

A total of 5 case-control or cross-sectional studies and 4 cohort studies with 7 794 087 study participants were included. Significant associations were found between psoriasis and Crohn disease (odds ratio, 1.70; 95% CI, 1.20-2.40) and between psoriasis and ulcerative colitis (odds ratio, 1.75; 95% CI, 1.49-2.05). Patients with psoriasis had an increased risk of Crohn disease (risk ratio, 2.53; 95% CI, 1.65-3.89) and ulcerative colitis (risk ratio, 1.71; 95% CI, 1.55-1.89).

Conclusions and Relevance

These findings suggest that psoriasis is significantly associated with IBD. Gastroenterology consultation may be indicated when patients with psoriasis present with bowel symptoms.

Bacterial modulation of visceral sensation: mediators and mechanisms

The potential role of the intestinal microbiota in modulating visceral pain has received increasing attention during recent years. This has led to the identification of signaling pathways that have been implicated in communication between gut bacteria and peripheral pain pathways. In addition to the well-characterized impact of the microbiota on the immune system, which in turn affects nociceptor excitability, bacteria can modulate visceral afferent pathways by effects on enterocytes, enteroendocrine cells, and the neurons themselves. Proteases produced by bacteria, or by host cells in response to bacteria, can increase or decrease the excitability of nociceptive dorsal root ganglion (DRG) neurons depending on the receptor activated. Short-chain fatty acids generated by colonic bacteria are involved in gut-brain communication, and intracolonic short-chain fatty acids have pronociceptive effects in rodents but may be antinociceptive in humans. Gut bacteria modulate the synthesis and release of enteroendocrine cell mediators, including serotonin and glucagon-like peptide-1, which activate extrinsic afferent neurons. Deciphering the complex interactions between visceral afferent neurons and the gut microbiota may lead to the development of improved probiotic therapies for visceral pain.

Pharmacological inhibition of NPY receptors illustrates dissociable features of experimental colitis in the mouse DSS model: Implications for preclinical evaluation of efficacy in an inflammatory bowel disease model

Administration of dextran sodium sulfate (DSS) to rodents at varying concentrations and exposure times is commonly used to model human inflammatory bowel disease (IBD). Currently, the criteria used to assess IBD-like pathology seldom include surrogate measures of visceral pain. Thus, we sought to standardize the model and then identify surrogate measures to assess effects on visceral pain. We used various 4% DSS protocols and evaluated effects on weight loss, colon pathology, biochemistry, RNA signature, and open field behavior. We then tested the therapeutic potential of NPY Y1 and/or Y2 receptor inhibition for the treatment of IBD pathology using this expanded panel of outcome measures. DSS caused weight loss and colon shrinkage, increased colon NPY and inflammatory cytokine expression, altered behaviors in the open field and induced a distinct gene metasignature that significantly overlapped with that of human IBD patients. Inhibition of Y1 and/or Y2 receptors failed to improve gross colon pathology. Y1 antagonism significantly attenuated colon inflammatory cytokine expression without altering pain-associated behaviors while Y2 antagonism significantly inhibited pain-associated behaviors in spite of a limited effect on inflammatory markers. A protocol using 7 days of 4% DSS most closely modeled human IBD pathology. In this model, rearing behavior potentially represents a tool for evaluating visceral pain/discomfort that may be pharmacologically dissociable from other features of pathology. The finding that two different NPY receptor antagonists exhibited different efficacy profiles highlights the benefit of including a variety of outcome measures in IBD efficacy studies to most fully evaluate the therapeutic potential of experimental treatments.

Rectus sheath catheters-a novel approach to perioperative analgesia for colorectal surgery in an enhanced recovery after surgery (ERAS) protocol: a case series

INTRODUCTION

Opioids have played a critical role in the management of perioperative pain following abdominal surgery. Increasing attention is being paid to the deleterious side effects and limitations of this practice. This case report offers a novel alternative to opioid-based analgesia in the form of rectus sheath catheters (RSCs) which we employed as part of an enhanced recovery after surgery (ERAS) protocol.

METHODS

Three patients underwent laparoscopic- assisted colorectal surgery and were treated intra- and postoperatively with local anesthesia administered via bilateral rectus sheath catheters as well as by multimodal adjuncts. Evaluations of the patients' pain scores, opioid usage, and abdominal sensitivity to sharp stimuli were conducted daily.

RESULTS

The patients demonstrated a substantially lessened opioid requirement over their hospital stay with two of them requiring no opioid analgesic medications postoperatively.

DISCUSSION

We suggest that the incorporation of these catheters into an ERAS protocol can play an important role in further reducing perioperative opioid usage for procedures in which pain control can be especially challenging.

Evaluating the psychometric properties of the Widespread Pain Index and the Symptom Severity scale in youth with painful conditions

Background

Assessing features of centralized pain may prove to be clinically meaningful in pediatric populations. However, we are currently limited by the lack of validated pediatric measures.

Aim

We examined the psychometric properties of the Widespread Pain Index (WPI) and Symptom Severity (SS) scale, to assess features of centralized pain, in youth with painful conditions from three clinical samples: (1) musculoskeletal surgery, (2) headache, and (3) chronic pain.

Methods

Participants were 240 youth aged 10-18 years (Mage=14.8, SD=1.9) who completed the WPI and SS scale. Subsets of participants also completed additional measures of pain region, pain intensity, quality of life, pain interference and physical function.

Results

Increased features of centralized pain by age were seen for the WPI (r=0.27, p<0.01) and SS scale (r=0.29, p<0.01). Expected differences in sex were seen for the WPI (sex:t₁₃₂=-3.62, p<0.01), but not the SS scale (sex:t₂₂₃=-1.73, p=0.09). Reliability for the SS scale was adequate (α=.70). Construct validity was demonstrated through relationships between the WPI and pain regions (r=.57, p<0.01), and between the SS scale and quality of life (r=-.59, p<0.01) and pain interference (r=.56, p<0.01). Criterion validity was demonstrated by differences on the WPI between the surgery sample and the headache and chronic pain samples (F_2,237=17.55, p<0.001). Comprehension of the SS scale items was problematic for some youth.

Conclusions

The WPI showed adequate psychometric properties in youth; however the SS scale may need to be modified. Our findings support the need to develop psychometrically sound instruments for comprehensive assessment of pain in pediatric samples.

Eosinophils in Inflammatory Bowel Disease

Clinical investigations in inflammatory bowel disease (IBD) patients have provided increasing evidence that eosinophils contribute to chronic intestinal inflammation. Accumulation of eosinophils in the gastrointestinal tract correlates with the variations of eosinophil regulatory molecules; however, their role in gastrointestinal dysfunction in IBD has not been fully elucidated. This review will describe the development and characterization of gastrointestinal eosinophils, mechanisms of eosinophil recruitment to the gastrointestinal tract. Moreover, the eosinophil-induced changes to the enteric nervous system associated with disease severity and gastrointestinal dysfunction will be analyzed with suggestive molecular pathways for enteric neuronal injury. Current and potential therapeutic interventions targeting eosinophils will be discussed.

Acupuncture in Inflammatory Bowel Disease

Scientific research into the effects and mechanisms of acupuncture for gastrointestinal diseases including inflammatory bowel disease has been rapidly growing in the past several decades. In this review, we discuss the history, theory, and methodology of acupuncture and review potentially beneficial mechanisms of action of acupuncture for managing inflammatory bowel disease. Acupuncture has been shown to decrease disease activity and inflammation via increase of vagal activity in inflammatory bowel disease. Acupuncture has demonstrated beneficial roles in the regulation of gut dysbiosis, intestinal barrier function, visceral hypersensitivity, gut motor dysfunction, depression/anxiety, and pain, all of which are factors that can significantly impact quality of life in patients with inflammatory bowel disease. A number of clinical trials have been performed to investigate the therapeutic effects of acupuncture in ulcerative colitis and Crohn's disease. Although the data from these trials are promising, more studies are needed given the heterogeneous and multifactorial aspects of inflammatory bowel disease. There is also an important need to standardize acupuncture methodology, study designs, and outcome measurements.

Rectal enema of bupivacaine in cancer patients with tenesmus pain - case series

Introduction: Rectal tenesmus pain in cancer patients most frequently appears in patients with colon cancer, and as a consequence of radiotherapy of the hypogastrium region. Treatment with opioids and adjuvant analgesics is often ineffective. Patients and methods: Here, we report on two female patients diagnosed with colon and ovary cancer, respectively, who had very severe tenesmus pain (numerical rating scale 8-10) despite using high doses of opioids, including methadone with corticosteroids, anticonvulsants, antidepressants and ketamine. Results: In both patients, bupivacaine was administered via a rectal enema. In the first patient, bupivacaine was administered at a dose of 100 mg 0.1% (100 mL), and subsequently 100 mg 0.2% (50 mL), leading to effective analgesia for 8 and 12 hrs, respectively. In the second patient, 100 mg 0.1% (100 mL) was initially administered, followed by 100 mg 0.2% (50 mL), leading to effective analgesia for 12 and 17 hrs, respectively, with only dull abdominal pain reported that was relieved by 100 mg IV ketoprofen and complete disappearance of tenesmus pain. Rectal bupivacaine administration did not cause neurologic adverse effects, heart function disturbances or decreased blood pressure. A volume of 50 mL was enough to cover a painful area in the colon. Initial bupivacaine concentrations in the blood serum did not exceed 50 ng/mL and eventually dropped to 20 ng/mL and below. Conclusions: Administration of 100 mg bupivacaine as a rectal enema is safe and provides effective analgesia, and this procedure may be conducted in hospital departments and out-patient clinics. Furthermore, this procedure in the case of pain recurrence, can be repeated, and by providing effective pain relief often allows time for the patient to be transferred to a specialized pain center.

Painful neurotrophins and their role in visceral pain

Beyond their well-known role in embryonic development of the central and peripheral nervous system, neurotrophins, particularly nerve growth factor and brain-derived neurotrophic factor, exert an essential role in pain production and sensitization. This has mainly been studied within the framework of somatic pain, and even antibodies (tanezumab and fasinumab) have recently been developed for their use in chronic somatic painful conditions, such as osteoarthritis or low back pain. However, data suggest that neurotrophins also exert an important role in the occurrence of visceral pain and visceral sensitization. Visceral pain is a distressing symptom that prompts many consultations and is typically encountered in both 'organic' (generally inflammatory) and 'functional' (displaying no obvious structural changes in routine clinical evaluations) disorders of the gut, such as inflammatory bowel disease and irritable bowel syndrome, respectively. The present review provides a summary of neurotrophins as a molecular family and their role in pain in general and addresses recent investigations of the involvement of nerve growth factor and brain-derived neurotrophic factor in visceral pain, particularly that associated with inflammatory bowel disease and irritable bowel syndrome.

Central hypersensitivity - A model for persistent musculoskeletal pain in inflammatory bowel diseases

Pain is reported to affect over 70% of individuals with inflammatory bowel diseases (IBD), with abdominal and musculoskeletal (MSK) pain representing the most common complaints. MSK pain is typically considered within the narrow framework of inflammatory extraintestinal manifestations of IBD, resulting in a limited scope for the nature and underlying mechanisms participating in MSK pain experiences in this population. Symptoms related to central sensitization have recently demonstrated association with active IBD and worse MSK pain experiences, suggesting a potential roll for central mechanisms in MSK-related pain. Current literature exploring persistent pain in chronic inflammatory and MSK populations propose complex pain models comprised of dynamic nervous system relationships influenced by primary disease features and concomitant pain states, as well as affective and cognitive components. Nervous system contributions in the development and maintenance of persistent pain are postulated to include mechanisms of peripheral and central sensitization, changes in descending central modulation, as well as structural brain changes. These models go beyond current MSK pain models described in IBD literature, highlighting the need for new frameworks for considering MSK-related pain in IBD. Consequently, this paper proposes a broader theoretical model whereby central mechanisms, such as central sensitization and grey matter changes, as well as psychological and disease factors are suggested to modulate pain experiences in this population. Exploration of relationships within the proposed framework may provide not only a deeper understanding of the generation and maintenance of persistent MSK pain in IBD, but also highlight the need for new targeted management pathways in this population. This paper hypothesizes that exploration of central sensitization in IBD patients will demonstrate altered somatosensory functioning in patients with MSK pain, and that IBD activity and psychological factors will be associated with altered somatosensory functioning and worse pain experiences.

Psychological and Social Factors Associated with Pain in Inflammatory Bowel Disease: A Systematic Literature Review of the Evidence in Adult and Pediatric Studies

Background

Pain is commonly experienced in both active and dormant inflammatory bowel disease (IBD). Psychological and social factors, which can be key to pain experience, have been relatively neglected; the only prior comprehensive review focused solely on studies of adults. The present review, therefore, sought to systematically examine relationships between pediatric and adult experience of pain and psychosocial variables.

Method

Systematic searches of 5 databases were conducted to identify studies including measures of pain and psychosocial variables, in pediatric or adult IBD populations. Quality appraisal of studies was undertaken using a qualified assessment tool.

Results

Twenty-three articles met the inclusion criteria. Ten examined relationships between pain and psychosocial variables in adults, and 13 examined in pediatric populations. Inverse relationships were identified between pain and quality of life (QOL) in both populations, with potential differences in pain localization between the two populations. Psychological distress, notably depression, was also important in both populations, with inconsistent evidence for a role for anxiety in pediatric samples. Specific coping styles, and familial responses to communications, also appeared relevant, but with weaker evidence. There was substantial heterogeneity in measures, statistical analyses and sample characteristics, and quality appraisal revealed methodological weaknesses.

Conclusions

Significant relationships were found between pain and various psychological indices, notably QOL and depression. However, most studies were underpowered, did not sufficiently control for key confounds, and almost exclusively reported on Western participants. Adequately powered, statistically sound studies encompassing diverse populations are required to further clarify relationships between pain and psychosocial variables in IBD.

Role of TRPV1 and TRPA1 Ion Channels in Inflammatory Bowel Diseases: Potential Therapeutic Targets?

Inflammatory bowel diseases (IBD) have long been recognized to be accompanied by pain resulting in high morbidity. Transient receptor potential vanilloid 1 (TRPV1) and ankyrin 1 (TRPA1) ion channels located predominantly on the capsaicin-sensitive sensory neurons play a complex role in hyperalgesia and neurogenic inflammation. This review provides an overview of their expression and role in intestinal inflammation, in particular colitis, that appears to be virtually inconsistent based on the thorough investigations of the last twenty years. However, preclinical results with pharmacological interventions, as well as scarcely available human studies, more convincingly point out the potential therapeutic value of TRPV1 and TRPA1 antagonists in colitis and visceral hypersensitivity providing future therapeutical perspectives through a complex, unique mechanism of action for drug development in IBD.

Performance of behavioral assays: the Rat Grimace Scale, burrowing activity and a composite behavior score to identify visceral pain in an acute and chronic colitis model

INTRODUCTION

The Rat Grimace Scale (RGS), a facial expression scale, quantifies the affective component of pain in rats. The RGS was developed to identify acute and inflammatory pain, and applicability in acute and chronic visceral pain is unknown. The dextran sulfate sodium (DSS) colitis model is commonly used in rats, but pain is rarely assessed, instead, disease progression is monitored with the Disease Activity Index (DAI; assessing fecal blood, stool consistency, and weight loss).

OBJECTIVES

The aim of this study was to assess whether the RGS and 2 additional behavioral tools (composite behavior score [CBS] and burrowing) could identify pain in an acute and chronic DSS colitis model.

METHODS

Male and female Sprague-Dawley rats were block randomized to (1) acute colitis (4 days DSS in drinking water); (2) chronic colitis (4 days DSS, 7 days water, and 3 days DSS); or (3) control (14 days water). Disease Activity Index, RGS, CBS, and burrowing assessments were performed daily.

RESULTS

Rat Grimace Scale scores increased as DAI scores increased during both acute and chronic phases. Burrowing only decreased during the acute phase. By contrast, CBS scores did not increase significantly during either colitis phase.

CONCLUSIONS

These data show that the RGS and burrowing did not decrease in a sustained manner during chronic phase visceral pain, and that variables assessed in the DAI are indicative of pain. This suggests that the RGS can be applied to a wider range of pain types and chronicity than originally suggested. These findings increase the application of the RGS as a pain scale and welfare improvement tool.

Implementation of an enhanced recovery program in pediatric laparoscopic colorectal patients does not worsen analgesia despite reduced perioperative opioids: a retrospective, matched, non-inferiority study

Background and objectives

Enhanced recovery protocols (ERPs) decrease length of stay and postoperative morbidity, but it is important that these benefits do not come at a cost of sacrificing proper perioperative analgesia. In this retrospective, matched cohort study, we evaluated postoperative pain intensity in pediatric patients who underwent laparoscopic colorectal surgeries before and after ERP implementation.

Methods

Patients in each cohort were randomly matched based on age, diagnosis, American Society of Anesthesiologists classification, and surgical procedure. The primary outcome was average daily postoperative pain score, while the secondary outcomes included postoperative hospital length of stay, complication rate, and 30-day readmissions. Since our hypothesis was non-inferior analgesia in the postprotocol cohort, a non-inferiority study design was used.

Results

After matching, 36 pairs of preprotocol and postprotocol patients were evaluated. ERP patients had non-inferior recovery room pain scores (difference 0 (−1.19, 0) points, 95% CI −0.22 to 0.26 points, p valuenon-inferiority <0.001) and 4-day postoperative pain scores (difference −0.3±1.9 points, 95% CI −0.82 to 0.48 points, p valuenon-inferiority <0.001) while receiving less postoperative opioids (difference −0.15 [−0.21, –0.05] intravenous morphine equivalents/kg/day, p<0.001). ERP patients also had reduced postoperative hospital stays (difference −1.5 [−4.5, 0] days, p<0.001) and 30-day readmissions (2.8% vs 27.8%, p=0.008).

Conclusions

Implementation of our ERP for pediatric laparoscopic colorectal patients was associated with less perioperative opioids without worsening postoperative pain scores. In addition, patients who received the protocol had faster return of bowel function, shorter postoperative hospital stays, and a lower rate of 30-day hospital readmissions. In pediatric laparoscopic colorectal patients, the incorporation of an ERP was associated with a pronounced decrease in perioperative morbidity without sacrificing postoperative analgesia.

Antibiotics in inflammatory bowel diseases: do we know what we're doing?

Despite the revolution in inflammatory bowel disease (IBD) treatment over the past two decades with the advent of biological therapies, there remains a substantial proportion of patients with inadequate or unsustained response to existent therapies. The overwhelming focus of IBD therapeutics has been targeting mucosal immunity, however with the developing evidence base pointing to the role of gut microbes in the inflammatory process, renewed focus should be placed on the impact of manipulating the microbiome in IBD management. This review provides an overview of the evidence implicating bacteria in the pathogenesis of gut inflammation in IBD and provides an overview of the evidence of antibiotics in IBD treatment. We also suggest a potential role of antibiotics in clinical practice based on available evidence and clinical experience.

Focus on current and future management possibilities in inflammatory bowel disease-related chronic pain

INTRODUCTION

Visceral pain is a symptom reported by over 70% of inflammatory bowel disease (IBD) sufferers. So far, a single, specific cause of this debilitating state has not been established. Chronic pain is one of the most important factors decreasing the quality of life in IBD course. Concurrently, management of pain is the most challenging issue encountered by clinicians in IBD treatment.

AREAS COVERED

This review focuses on pathophysiology of inflammatory bowel disease-caused visceral pain and explores currently available approaches to its management. We also covered recent pharmacological developments in the field.

CONCLUSIONS

Pain-related disability has major effects on quality of life and on functional and social outcomes in IBD patients. Currently, there is no one standardized method of managing chronic visceral pain in IBD. Therefore, future development, focusing primarily on alleviating the pain, but also on reducing inflammation, is essential.

Homozygosity for the SCN10A Polymorphism rs6795970 Is Associated With Hypoalgesic Inflammatory Bowel Disease Phenotype

Background: Hypoalgesic inflammatory bowel disease (IBD), a condition in which patients with active disease do not perceive and/or report abdominal pain, is associated with serious complications and there is a lack of cost-effective, reliable diagnostic methods to identify “at-risk” patients. The voltage-gated sodium channels (VGSC's), Na_v1.7, Na_v1.8, and Na_v1.9, are preferentially expressed on nociceptive neurons, and have been implicated in visceral inflammatory pain. At least 29 VGSC single nucleotide polymorphisms (SNPs) have been implicated in chronic somatic pain syndromes, but little is known about their role in human visceral sensation. We hypothesized that disruptive VGSC polymorphisms result in anti-nociceptive behavior in IBD.

Methods and Findings: We performed targeted exome sequencing and/or TaqMan genotyping to evaluate the Na_v1.7, Na_v1.8, and Na_v1.9 genes (SCN9A, SCN10A and SCN11A) in 121 IBD patients (including 41 “hypoalgesic” IBD patients) and 86 healthy controls. Allelic and genotypic frequencies of polymorphisms were compared among study groups who had undergone characterization of intestinal inflammatory status and abdominal pain experience. Forty-nine total exonic SNPs were identified. The allelic frequency of only one non-synonymous SNP (rs6795970 [SCN10A]) approached significance in hypoalgesic IBD patients when compared to other IBD patients (p = 0.096, Fisher's exact test). Hypoalgesic IBD patients were more likely to be homozygous for this polymorphism (46 vs. 22%, p = 0.01, Fisher's exact test).

Conclusions: This is the first human study to demonstrate a link between a genetic variant of SCN10A and abdominal pain perception in IBD. These findings provide key insights into visceral nociceptive physiology and new diagnostic and therapeutic targets to consider in IBD and other gastrointestinal conditions associated with chronic abdominal pain. Further studies are required to elucidate the precise pathophysiological impact of the rs6795970 polymorphism on human gastrointestinal nociception.

Enteric Glia: A New Player in Abdominal Pain

Chronic abdominal pain is the most common gastrointestinal issue and contributes to the pathophysiology of functional bowel disorders and inflammatory bowel disease. Current theories suggest that neuronal plasticity and broad alterations along the brain-gut axis contribute to the development of chronic abdominal pain, but the specific mechanisms involved in chronic abdominal pain remain incompletely understood. Accumulating evidence implicates glial cells in the development and maintenance of chronic pain. Astrocytes and microglia in the central nervous system and satellite glia in dorsal root ganglia contribute to chronic pain states through reactive gliosis, the modification of glial networks, and the synthesis and release of neuromodulators. In addition, new data suggest that enteric glia, a unique type of peripheral glia found within the enteric nervous system, have the potential to modify visceral perception through interactions with neurons and immune cells. Understanding these emerging roles of enteric glia is important to fully understand the mechanisms that drive chronic pain and to identify novel therapeutic targets. In this review, we discuss enteric glial cell signaling mechanisms that have the potential to influence chronic abdominal pain.

Targeting eotaxin-1 and CCR3 receptor alleviates enteric neuropathy and colonic dysfunction in TNBS-induced colitis in guinea pigs

BACKGROUND

The accumulation of eosinophils is mediated by the chemokine receptor-3 (CCR3)-eotaxin axis. Increased expression of eotaxin and its receptor is associated with inflammatory bowel disease (IBD). Activation of eosinophils causes the release of cationic proteins that are neurotoxic such as eosinophil-derived neurotoxin (EDN). Damage to enteric neurons alters neurally controlled functions of the gut correlated with intestinal inflammation. We hypothesized that inhibition of the CCR3-eotaxin axis will prevent inflammation-induced functional changes to the gastrointestinal tract.

METHODS

Hartley guinea pigs were administered with trinitrobenzene sulfonate (TNBS; 30 mg/kg in 30% ethanol) intrarectally to induce colitis. A CCR3 receptor antagonist (SB 328437 [SB3]) was injected intraperitoneally 1 hour postinduction of colitis. Animals were euthanized 7 days post-treatment and colon tissues were collected for ex vivo studies. The EDN-positive eosinophils in the colon, indicating eosinophil activation, were quantified by immunohistochemistry. Effects of SB3 treatment on gross morphological damage, enteric neuropathy, and colonic dysmotility were determined by histology, immunohistochemistry, and organ bath experiments.

KEY RESULTS

The number of EDN-positive eosinophils was significantly increased in the lamina propria in close proximity to myenteric ganglia in inflamed colon. The TNBS-induced inflammation caused significant damage to colonic architecture and inhibition of colonic motility. Treatment with SB3 antagonist attenuated inflammation-associated morphological damage in the colon, reduced infiltration of EDN-positive eosinophils and restored colonic motility to levels comparable to control and sham-treated guinea pigs.

CONCLUSION & INFERENCES

This is the first study demonstrating that inhibition of CCR3-eotaxin axis alleviates enteric neuropathy and restores functional changes in the gut associated with TNBS-induced colitis.

Colitis-induced alterations in response properties of visceral nociceptive neurons in the rat caudal medulla oblongata and their modulation by 5-HT3 receptor blockade

There is considerable clinical and experimental evidence that intestinal inflammation is associated with altered visceral nociceptive processing in the spinal cord and brain, but the underlying neuronal mechanisms, especially acting at the supraspinal level, remain unclear. Considering that the caudal ventrolateral medulla (CVLM) and the nucleus tractus solitarius (NTS) are the first sites for supraspinal processing of visceral pain signals, in the present study we evaluated the experimental colitis-induced changes in response properties of CVLM and NTS medullary neurons to noxious colorectal distension (CRD) in urethane-anesthetized adult male Wistar rats. To determine if gut inflammation alters the 5-HT₃ receptor-dependent modulation of visceral pain-related CVLM and NTS cells, we examined the effects of intravenously administered selective 5-HT₃ antagonist granisetron on ongoing and CRD-evoked activity of CVLM and NTS neurons in healthy control and colitic animals. In the absence of colonic pathology, the CVLM neurons were more excited by noxious CRD that the NTS cells, which demonstrated a greater tendency to be inhibited by the stimulation. The difference was eliminated after the development of colitis due to the increase in the proportion of CRD-excited neurons in both medullary regions associated with enhanced magnitude of the neuronal nociceptive responses. Intravenous granisetron (1 or 2 mg/kg) produced the dose-dependent suppression of the ongoing and evoked firing of CRD-excited cells within both the CVLM and NTS in normal conditions as well as was able to substantially reduce excitability of the caudal medullary neurons in the presence of colonic inflammation, arguing for the potential efficacy of the 5-HT₃ receptor blockade with granisetron against both acute and inflammatory abdominal pain. Taken together, the data obtained can contribute to a deeper understanding of supraspinal serotonergic mechanisms responsible for the persistence of visceral hypersensitivity and hyperalgesia triggered by colonic inflammation.

Antibiotics in IBD: Still a Role in the Biological Era?

Despite compelling evidence pointing to a critical role of gut microflora in inflammatory bowel disease (IBD) pathogenesis, the role of antibiotics in clinical practice remains limited, largely due to heterogeneous trials with often conflicting evidence. In this review, we revisit previous randomized controlled trials and high-quality uncontrolled studies in an effort to better elucidate the role of antibiotics in contemporary treatment algorithms. The most established role of antibiotics is in perianal Crohn's disease (CD), utilizing ciprofloxacin with or without metronidazole often as an adjunct to biological therapy. Evidence also points to a likely modest role of various antibiotic classes in mild to moderate luminal CD, including ciprofloxacin, metronidazole, azithromycin, and rifaximin. The benefit of metronidazole in preventing postoperative recurrence in CD is well reported; however, the long-term benefit of this intervention remains uncertain. The use of antibiotics in ulcerative colitis (UC) is even more controversial, but studies using broad-spectrum oral antibiotic cocktails have reported a possible role in acute severe colitis and chronic persistent UC. Similarly, the role of oral vancomycin and gentamicin in very early-onset IBD has interesting preliminary results. Adverse events of antibiotics, the resulting alterations in the microbiome with its associated unknown long-term sequela, and the emergence of antibiotic-resistant strains must be carefully balanced. Therefore, although antibiotics may be underused in the treatment of IBD, their integration into clinical practice must be approached judiciously and individually.

Pediatric Crohn's Disease in Bahrain

OBJECTIVES

Our study aimed to report the epidemiology, clinical presentations, diagnostic and therapeutic approaches, and outcomes of Crohn's disease (CD) in pediatric patients in Bahrain.

METHODS

We conducted a retrospective review of the medical records of patients with CD diagnosed in the pediatric department, Salmaniya Medical Complex, Bahrain, between 1984 and 2017. We used the data to calculate the annual incidence and cumulative prevalence. Data about gender, nationality, clinical presentation, age at presentation and diagnosis, duration of illness, consanguinity, family history, contact with smokers, and comorbidities were gathered. Results of hematological, biochemical, and serological tests were also collected. All radiological, endoscopic, and histopathological findings were reviewed. Data about medical therapy, relapse episodes, hospital admissions, complications, and outcomes were collected.

RESULTS

Of 108 pediatric patients diagnosed with inflammatory bowel disease (IBD), 51 (47.2%) patients had CD. The annual incidence was 1 in 100 000 per year (range = 0-5 patients/year) with significant rise on comparing the three decades (p = 0.0001). Prevalence was 9.32 patients per 100 000 pediatric populations. Thirty-four patients (66.7%) were males, and the median age was 18.5 years (range = 6.4-35.0). Common clinical presentations were recurrent abdominal pain and weight loss. Family history of IBD was found in 10 patients. One patient had positive antineutrophil cytoplasmic antibody. The terminal ileum was involved in 68.1%, colon in 63.8%, and perianal area in 17.0% patients. Biological therapy was used in five patients. Surgical intervention was required in six patients. The mean follow-up period was 9.2±5.6 years.

CONCLUSIONS

The clinical characteristics of our population are comparable to that reported in neighboring countries and worldwide.

Co-expression of μ and δ opioid receptors by mouse colonic nociceptors

BACKGROUND AND PURPOSE

To better understand opioid signalling in visceral nociceptors, we examined the expression and selective activation of μ and δ opioid receptors by dorsal root ganglia (DRG) neurons innervating the mouse colon.

EXPERIMENTAL APPROACH

DRG neurons projecting to the colon were identified by retrograde tracing. δ receptor-GFP reporter mice, in situ hybridization, single-cell RT-PCR and μ receptor-specific antibodies were used to characterize expression of μ and δ receptors. Voltage-gated Ca²⁺ currents and neuronal excitability were recorded in small diameter nociceptive neurons (capacitance <30 pF) by patch clamp and ex vivo single-unit afferent recordings were obtained from the colon.

KEY RESULTS

In situ hybridization of oprm1 expression in Fast Blue-labelled DRG neurons was observed in 61% of neurons. μ and δ receptors were expressed by 36-46% of colon DRG neurons, and co-expressed by ~25% of neurons. μ and δ receptor agonists inhibited Ca²⁺ currents in DRG, effects blocked by opioid antagonists. One or both agonists inhibited action potential firing by colonic afferent endings. Incubation of neurons with supernatants from inflamed colon segments inhibited Ca²⁺ currents and neuronal excitability. Antagonists of μ, but not δ receptors, inhibited the effects of these supernatant on Ca²⁺ currents, whereas both antagonists inhibited their actions on neuronal excitability.

CONCLUSIONS AND IMPLICATIONS

A significant number of small diameter colonic nociceptors co-express μ and δ receptors and are inhibited by agonists and endogenous opioids in inflamed tissues. Thus, opioids that act at μ or δ receptors, or their heterodimers may be effective in treating visceral pain.

Inflammatory bowel disease and immunonutrition: novel therapeutic approaches through modulation of diet and the gut microbiome

Inflammatory bowel disease (IBD) is a chronic inflammatory condition of the gastrointestinal tract, thought to at least in part reflect an aberrant immune response to gut bacteria. IBD is increasing in incidence, particularly in populations that have recently immigrated to western countries. This suggests that environmental factors are involved in its pathogenesis. We hypothesize that the increase in IBD rates might reflect the consumption of an unhealthy Western diet, containing excess calories and lacking in key nutritional factors, such as fibre and vitamin D. Several recent studies have determined that dietary factors can dramatically influence the activation of immune cells and the mediators they release through a process called immunonutrition. Moreover, dietary changes can profoundly affect the balance of beneficial versus pathogenic bacteria in the gut. This microbial imbalance can alter levels of microbiota-derived metabolites that in turn can influence innate and adaptive intestinal immune responses. If the diet-gut microbiome disease axis does indeed underpin much of the 'western' influence on the onset and progression of IBD, then tremendous opportunity exists for therapeutic changes in lifestyle, to modulate the gut microbiome and to correct immune imbalances in individuals with IBD. This review highlights four such therapeutic strategies - probiotics, prebiotics, vitamin D and caloric restriction - that have the potential to improve and add to current IBD treatment regimens.

Altered Brain Excitability and Increased Anxiety in Mice With Experimental Colitis: Consideration of Hyperalgesia and Sex Differences

Crohn’s disease (CD) and ulcerative colitis (UC) are incurable lifelong inflammatory bowel diseases (IBD) with a rising worldwide incidence. IBD is characterized by diarrhea, rectal bleeding, severe cramping and weight loss. However, there is a growing evidence that IBD is also associated with anxiety- and depression-related disorders, which further increase the societal burden of these diseases. Given the limited knowledge of central nervous system (CNS) changes in IBD, we investigated CNS-related comorbidities in a mouse model of experimental colitis induced by dextran sulfate sodium (DSS) administration in drinking water for 5 days. In male and female C57BL6J mice, DSS treatment caused increased brain excitability, revealed by a decrease in seizure onset times after intraperitoneal administration of kainic acid. Moreover, both sexes showed increased anxiety-related behavior in the elevated plus-maze (EPM) and open field (OF) paradigms. We assessed somatic pain levels, because they may influence behavioral responses. Only male mice were hyperalgesic when tested with calibrated von Frey hairs and on the hotplate for mechanical and thermal pain sensitivity respectively. Administration of diazepam (DZP; ip, 1 mg/kg) 30 min before EPM rescued the anxious phenotype and improved locomotion, even though it significantly increased thermal sensitivity in both sexes. This indicates that the altered behavioral response is unlikely attributable to an interference with movement due to somatic pain in females. We show that experimental colitis increases CNS excitability in response to administration of kainic acid, and increases anxiety-related behavior as revealed using the EPM and OF tests.