Central sensitization and severity of gastrointestinal symptoms in irritable bowel syndrome, chronic pain syndromes, and inflammatory bowel disease

The Development of Persistent Gastrointestinal Symptoms in Patients With Melanoma Who Have Had an Immune Checkpoint Inhibitor-Related Gastrointestinal Toxicity

INTRODUCTION

Immune-related adverse events (irAE) secondary to immune checkpoint inhibitors (ICI) have gastrointestinal (GI) manifestations, including gastritis, enteritis, and/or colitis. The long-term sequelae of ICI-associated GI toxicities (GI-irAE), particularly the development of disorders of gut-brain interaction, are not well known. We characterized the incidence of persistent GI symptoms after GI-irAE.

METHODS

This is a retrospective study of adults with melanoma treated with ICI and diagnosed with GI-irAE at our institution from 2013 to 2021. All patients had endoscopic and histologic evidence of GI-irAE. The primary outcome was incidence of persistent GI symptoms (diarrhea, abdominal pain, bloating, constipation, fecal incontinence, nausea, vomiting) after resolution of GI-irAE. Hazard ratios evaluated the association between parameters and time to persistent GI symptoms.

RESULTS

One hundred four patients with melanoma (90% stage IV disease) and GI-irAE met inclusion criteria. Thirty-four percent received anti-cytotoxic T lymphocyte-associated protein-4 therapy, 33% anti-programmed death-1, and 34% dual therapy. Patients were treated for GI-irAE for an average of 9 ± 6 weeks. Twenty-eight (27%) patients developed persistent GI symptoms 1.6 ± 0.8 years after GI-irAE. The most common symptom was constipation (17%), followed by bloating (8%) and diarrhea (5%). Over 453 person-years, the incident rate was 6.2% per 100 person-years. Use of cytotoxic T lymphocyte-associated protein-4 single or dual therapy was associated with a 3.51× risk of persistent GI symptoms (95% confidence interval 1.20-10.23).

DISCUSSION

In this cohort of melanoma patients who experienced GI-irAE, 26% developed persistent GI symptoms, most frequently constipation. Future studies should characterize the GI sequelae after GI-irAE, which may shed light on disorders of gut-brain interaction pathogenesis and improve the lives of cancer survivors.

Dorsoventral hippocampus distinctly modulates visceral sensitivity and anxiety behaviors in male IBS-like rats

Accumulating evidences suggest dysfunctions in the hippocampus are associated with chronic pain. Nevertheless, the role of hippocampal circuitry in pain memories and emotional responses is not yet fully understood. In this study, we utilized a comprehensive approach that combined electromyography (EMG), photochemical genetic techniques, and anxiety-related behavioral paradigms to investigate the involvement of dorsal hippocampus (DH) and ventral hippocampus (VH) in visceral sensitivity and anxiety behaviors in male rats. Our results demonstrated that IBS-like rats exhibited comorbid visceral hypersensitivity and anxiety, along with the number of activated neurons in the VH was higher than that in the DH. Manipulation of glutamatergic neurons in the hippocampus was identified as a crucial mechanism underlying the mediation of both visceral sensitivity and anxiety behaviors. Specifically, optogenetic activation of the DH induced both visceral hypersensitivity and anxiety, while activation of the VH induced anxiety but did not affect visceral sensitivity. Conversely, chemogenetic inhibition of the DH reduced both visceral hypersensitivity and anxiety, whereas inhibition of the VH alleviated anxiety but did not alleviate visceral hypersensitivity in IBS-like rats. Our study highlights the important role of early life stress in inducing visceral hypersensitivity and anxiety, and further elucidates the distinct functional contributions of the DH and VH to these behavioral changes. These findings provide a theoretical basis for the diagnosis and treatment of IBS, and suggest that targeting specific hippocampal neuron subtypes may represent a promising therapeutic approach.

Reproducible microbiome composition signatures of anxiety and depressive symptoms

The gut microbiome is a significant contributor to mental health, with growing evidence linking its composition to anxiety and depressive disorders. Gut microbiome composition is associated with signs of anxiety and depression both in clinically diagnosed mood disorders and subclinically in the general population and may be influenced by dietary fibre intake and the presence of chronic pain. We provide an update of current evidence on the role of gut microbiome composition in depressive and anxiety disorders or symptoms by reviewing available studies. Analysing data from three independent cohorts (osteoarthritis 1 (OA1); n = 46, osteoarthritis 2 (OA2); n = 58, and healthy controls (CON); n = 67), we identified microbial composition signatures of anxiety and depressive symptoms at genus level and cross-validated our findings performing meta-analyses of our results with results from previously published studies. The genera Bifidobacterium (fixed-effect beta (95% CI) = -0.22 (-0.34, -0.10), p = 3.90e-04) and Lachnospiraceae NK4A136 group (fixed-effect beta (95% CI) = -0.09 (-0.13, -0.05), p = 2.53e-06) were found to be the best predictors of anxiety and depressive symptoms, respectively, across our three cohorts and published literature taking into account demographic and lifestyle covariates, such as fibre intake. The association with anxiety was robust in accounting for heterogeneity between cohorts and supports previous observations of the potential prophylactic effect of Bifidobacterium against anxiety symptoms.

Does sourdough bread provide clinically relevant health benefits?

During the last decade, scientific interest in and consumer attention to sourdough fermentation in bread making has increased. On the one hand, this technology may favorably impact product quality, including flavor and shelf-life of bakery products; on the other hand, some cereal components, especially in wheat and rye, which are known to cause adverse reactions in a small subset of the population, can be partially modified or degraded. The latter potentially reduces their harmful effects, but depends strongly on the composition of sourdough microbiota, processing conditions and the resulting acidification. Tolerability, nutritional composition, potential health effects and consumer acceptance of sourdough bread are often suggested to be superior compared to yeast-leavened bread. However, the advantages of sourdough fermentation claimed in many publications rely mostly on data from chemical and in vitro analyzes, which raises questions about the actual impact on human nutrition. This review focuses on grain components, which may cause adverse effects in humans and the effect of sourdough microbiota on their structure, quantity and biological properties. Furthermore, presumed benefits of secondary metabolites and reduction of contaminants are discussed. The benefits claimed deriving from in vitro and in vivo experiments will be evaluated across a broader spectrum in terms of clinically relevant effects on human health. Accordingly, this critical review aims to contribute to a better understanding of the extent to which sourdough bread may result in measurable health benefits in humans.

Sadness and Anxiety Modify the Relationship Between COVID-19 and Gastrointestinal Symptoms at 6-12 Months of Follow-up

Background and Aims

It is unclear to what degree post-COVID-19 gastrointestinal (GI) symptoms are caused by the SARS-CoV-2 virus vs psychological factors related to the stress of the pandemic. To evaluate this, we compared rates of long-term GI and mental health symptoms in patients testing positive vs negative for SARS-CoV-2.

Methods

Adults presenting for SARS-CoV-2 testing from April to November 2020 were prospectively enrolled in a longitudinal cohort. Six to 12 months later, the presence and severity of current GI and mental health symptoms were assessed on a 5-point Likert scale. A multivariable logistic regression model was used to estimate the odds of a positive COVID test for predicting GI symptoms, stratified by sadness/anxiety.

Results

749 COVID-positive and 107 COVID-negative patients completed the survey. The prevalence of at least one GI symptom was higher in patients with COVID-19 (29 vs 18%, P = .01). However, after stratifying by sadness/anxiety, differences in GI symptoms according to COVID status were no longer significant. On multivariable analysis, the adjusted odds ratio for GI symptoms was 8.26 (95% CI 4.04-16.9) for positive COVID with sadness/anxiety, 8.74 (95% CI 2.63-29.0) for negative COVID with sadness/anxiety, and 1.16 (95% CI 0.57-2.39) for positive COVID without sadness/anxiety, compared to a reference group of negative COVID without sadness/anxiety.

Conclusion

After accounting for sadness and anxiety, there was no association between COVID-19 and the development of long-term GI symptoms. Post-COVID GI symptoms may be mediated bidirectionally through coexisting anxiety and depression, similar to disorders of gut-brain interaction.

Do "central sensitization" questionnaires reflect measures of nociceptive sensitization or psychological constructs? A systematic review and meta-analyses

ABSTRACT

Central sensitization (CS) is defined as an increased nociceptive responsiveness due to sensitization of neurons in the central nervous system, usually the result of prolonged nociceptive input or a disease state associated with noxious inputs (eg, polyarthritis). The concept of CS has recently been adopted in clinical assessments of chronic pain, but its diagnosis in humans may now include a wide range of hypervigilant responses. The purpose of this review is to ascertain whether self-report questionnaires linked with CS are associated with enhanced nociceptive responses or whether they measure sensitivity in a broader sense (ie, emotional responses). According to our published, PROSPERO-registered review protocol (CRD42021208731), a predefined search of studies that involve the Central Sensitization Inventory (CSI) or Pain Sensitivity Questionnaire (PSQ), correlated with either nociceptive sensory tests or emotional hypervigilance was conducted on MEDLINE, PsycINFO, and Web of Science. Correlations between the CSI or PSQ with our primary outcomes were extracted and meta-analysed. A review of 66 studies totalling 13,284 participants found that the CSI (but not the PSQ) strongly correlated with psychological constructs: depression, anxiety, stress, pain catastrophising, sleep, and kinesiophobia. The CSI and PSQ showed weak or no correlations with experimental measures of nociceptive sensitivity: pain thresholds, temporal summation, or conditioned pain modulation. The PSQ did, however, correlate strongly with phasic heat and tonic cold pain tests. The studies reviewed did not provide sufficient evidence that self-report measures reflect a canonical understanding of CS. The CSI more closely reflects psychological hypervigilance than increased responsiveness of nociceptive neurons.

Comorbid extra-intestinal central sensitization conditions worsen irritable bowel syndrome in primary care patients

BACKGROUND

Irritable bowel syndrome (IBS) is characterized as a central sensitization syndrome (CSS), a group of conditions including fibromyalgia, chronic fatigue, and restless leg syndrome (RLS) among others with frequent comorbidities of anxiety, depression, and chemical sensitivity. The prevalence of comorbid conditions and their impact on IBS symptom severity and quality of life in rural community populations has not been described.

METHODS

We administered a cross-sectional survey to patients with a documented CSS diagnosis in rural primary care practices to evaluate the relationship between CSS diagnoses, quality of life, symptom severity, and interactions with healthcare providers utilizing validated questionnaires. Subgroup analysis was performed on the IBS cohort. Mayo Clinic IRB approved the study.

KEY RESULTS

Seven hundred seventy-five individuals out of 5000 completed the survey (15.5% response rate) with 264 (34%) reporting IBS. Only 3% (n = 8) of IBS patients reported IBS alone without comorbid CSS condition. Most respondents reported overlapping migraine (196, 74%), depression (183, 69%), anxiety (171, 64%), and fibromyalgia (139, 52%). IBS patients with more than two comorbid CS condition showed significantly higher symptom severity with linear increase. Quality of life was lower in IBS with comorbid conditions, particularly in patients with IBS and RLS (mean EQ5-D 0.36 vs. 0.8 in IBS only, p < 0.01). Quality of life declined as number of comorbid conditions increased.

CONCLUSIONS & INFERENCES

Patients with IBS often have multiple CS disorders which increases symptom severity and lowers quality of life. Understanding the impact of multiple CSS diagnoses and treating these as a global condition may improve patient experience.

The neurobiology of irritable bowel syndrome

Irritable bowel syndrome (IBS) is the most prevalent disorder of brain-gut interactions that affects between 5 and 10% of the general population worldwide. The current symptom criteria restrict the diagnosis to recurrent abdominal pain associated with altered bowel habits, but the majority of patients also report non-painful abdominal discomfort, associated psychiatric conditions (anxiety and depression), as well as other visceral and somatic pain-related symptoms. For decades, IBS was considered an intestinal motility disorder, and more recently a gut disorder. However, based on an extensive body of reported information about central, peripheral mechanisms and genetic factors involved in the pathophysiology of IBS symptoms, a comprehensive disease model of brain-gut-microbiome interactions has emerged, which can explain altered bowel habits, chronic abdominal pain, and psychiatric comorbidities. In this review, we will first describe novel insights into several key components of brain-gut microbiome interactions, starting with reported alterations in the gut connectome and enteric nervous system, and a list of distinct functional and structural brain signatures, and comparing them to the proposed brain alterations in anxiety disorders. We will then point out the emerging correlations between the brain networks with the genomic, gastrointestinal, immune, and gut microbiome-related parameters. We will incorporate this new information into a systems-based disease model of IBS. Finally, we will discuss the implications of such a model for the improved understanding of the disorder and the development of more effective treatment approaches in the future.

An investigation of the relationship between cutaneous allodynia and kinesiophobia, gastrointestinal system symptom severity, physical activity and disability in individuals with migraine

Background

To investigate the relationship between cutaneous allodynia (CA) and kinesiophobia, gastrointestinal system (GIS) symptom severity, physical activity, and disability, and to determine whether CA, pain, and disability were influencing factors for kinesiophobia, GIS symptoms, and physical activity in individuals with migraine.

Methods

The study included 144 individuals with migraine. CA, kinesiophobia, GIS symptoms, physical activity level, and migraine-related disability were evaluated with the Allodynia Symptom Checklist, the Tampa Kinesiophobia Scale (TKS), the Gastrointestinal Symptom Rating Scale (GSRS), the International Physical Activity Questionnaire-7, and the Migraine Disability Assessment Scale (MIDAS), respectively.

Results

The CA severity was only associated with TKS (r = 0.515; P < 0.001), GSRS-total (r = 0.336; P < 0.001), GSRS-abdominal pain (r = 0.323; P < 0.001), GSRS-indigestion (r = 0.257; P = 0.002), GSRS-constipation (r = 0.371; P < 0.001), and MIDAS scores (r = 0.178; P = 0.033). Attack frequency (P = 0.015), attack duration (P = 0.035) and presence of CA (P < 0.001) were risk factors for kinesiophobia. Attack frequency (P = 0.027) and presence of CA (P = 0.004) were risk factors for GIS symptoms.

Conclusions

There was a relationship between the CA and kinesiophobia, GIS symptoms, and disability. CA and attack frequency were found to be risk factors for kinesiophobia and GIS symptoms. Migraine patients with CA should be assessed in terms of kinesiophobia, GIS, and disability. Lifestyle changes such as exercise and dietary changes and/or pharmacological treatment options for CA may increase success in migraine management.

Adaptation and validation of the Chinese version of the Central Sensitisation Inventory in patients with chronic pain

Background

The 25-item Central Sensitisation Inventory (CSI-25) is a patient-reported instrument used to screen patients at risk of central sensitisation, a pathophysiological mechanism implicated in many chronic pain syndromes.

Aims

To adapt and validate a Chinese version of the CSI-25 in the Chinese population.

Methods

The Chinese CSI-25 was developed by the translation of the original English version, back translation, cultural adaptation and revision using the Delphi method. The Chinese CSI-25 was administered to 237 patients with chronic pain and 55 healthy controls. Structural validity (confirmatory factor analysis), construct validity (correlations with other instruments), test-retest reliability and internal consistency were evaluated.

Results

Confirmatory factor analysis extracted four main factors ('physical symptoms', 'emotional distress', 'headache/jaw symptoms' and 'urological symptoms'). The Chinese CSI-25 score was positively correlated with the Pain Catastrophic Scale (PCS) total score (r=0.709), PCS subscale scores (r=0.630-0.695), Brief Pain Inventory (BPI) mean item score (r=0.773), BPI total score (r=0.773) and the number of painful sites (r=0.636). The Chinese CSI-25 had excellent test-retest reliability (intragroup correlation coefficient=0.975) and good internal consistency (Cronbach's α=0.930 in the overall population and 0.882 in the chronic pain population).

Conclusions

The Chinese CSI-25 had excellent test-retest reliability and satisfactory structural validity and construct validity. This instrument could potentially be used in China as a self-report questionnaire in both clinical practice and research settings.

Gravity and the Gut: A Hypothesis of Irritable Bowel Syndrome

The pathogenesis of irritable bowel syndrome (IBS)-a disorder of gut-brain interaction that affects up to 10% of the world's population-remains uncertain. It is puzzling that a disorder so prevalent and archetypal among humans can be explained by disparate theories, respond to treatments with vastly different mechanisms of action, and present with a dazzling array of comorbidities. It is reasonable to question whether there is a unifying factor that binds these divergent theories and observations, and if so, what that factor might be. This article offers a testable hypothesis that seeks to accommodate the manifold theories, clinical symptoms, somatic comorbidities, neuropsychological features, and treatment outcomes of IBS by describing the syndrome in relation to a principal force of human evolution: gravity. In short, the hypothesis proposed here is that IBS may result from ineffective anatomical, physiological, and neuropsychological gravity management systems designed to optimize gastrointestinal form and function, protect somatic and visceral integrity, and maximize survival in a gravity-bound world. To explain this unconventional hypothesis of IBS pathogenesis, referred to herein as the gravity hypothesis, this article reviews the influence of gravity on human evolution; discusses how Homo sapiens imperfectly evolved to manage this universal force of attraction; and explores the mechanical, microbial, and neuropsychological consequences of gravity intolerance with a focus on explaining IBS. This article concludes by considering the diagnostic and therapeutic implications of this new hypothesis and proposes experiments to support or reject this line of inquiry. It is hoped that the ideas in this thought experiment may also help encourage new or different ways of thinking about this common disorder.

Editorial: natural history of irritable bowel syndrome in inflammatory bowel disease

LINKED CONTENT

This article is linked to Fairbrass et al papers. To view these articles, visit https://doi.org/10.1111/apt.17193 and https://doi.org/10.1111/apt.17215

Risk Factors for Self-reported Irritable Bowel Syndrome With Prior Psychiatric Disorder: The Lifelines Cohort Study

Background/Aims

The role of psychiatric disorder in irritable bowel syndrome (IBS) is not clear. This study aims to assess whether individuals who have psychiatric disorder prior to IBS onset differ in their risk factors from the remainder.

Methods

The prospective, population-based Lifelines cohort study includes 132 922 adults without prior IBS or taking IBS medication at baseline. Baseline data included socio-demographic status, physical and psychiatric disorders, psycho-social and behavioral variables. At follow-up (mean 2.4 years later) new onsets of IBS were recorded by self-report. The predictors of new onsets of IBS were assessed using logistic regression; participants with and without prior psychiatric disorders were analyzed separately.

Results

At follow-up 1507 (1.1%) participants reported new onset IBS. Of these, 27% reported prior psychiatric disorder. Predictors of IBS in this group were 2 or more psychiatric disorders (OR, 2.74; 95% CI, 1.3-5.6), female sex, proton pump inhibitors, numerous bodily symptoms, impaired sleep, low BMI and negative health perception. These variables, except psychiatric disorders and BMI, also predicted IBS in those without prior psychiatric disorder but, in this group, gallstones, asthma, fibromyalgia, reported allergies, impairment through bodily pain, and frequent healthcare were also predictors.

Conclusions

Despite its limitations this study suggests that prior psychiatric disorder is an important risk factor in a quarter of IBS onsets. Negative health perception and multiple bodily symptoms are associated with all IBS onsets in line with the cognitive-behavior model of IBS. Prior psychiatric disorder may predict an optimal response to psychiatric treatment. Further studies could usefully study mechanisms linking IBS to prior psychiatric disorder.

Advances in the management of fibromyalgia: what is the state of the art?

INTRODUCTION

Fibromyalgia (FM) is a chronic pain syndrome associated with fatigue, insomnia, dyscognition, and emotional distress. Critical illness mechanisms include central sensitization to nociceptive and non-nociceptive stimuli often resulting in hypersensitivity to all sensory input.

AREAS COVERED

The clinical presentation of FM can vary widely and therefore requires therapies tailored to each patient's set of symptoms. This manuscript examines currently prescribed therapeutic approaches supported by empirical evidence as well as promising novel treatments. Although pharmacological therapy until now has been only moderately effective for FM symptoms, it represents a critical component of every treatment plan.

EXPERT OPINION

Currently approved pharmacological therapies for FM symptoms have limited but proven effectiveness. Novel therapies with cannabinoids and naltrexone appear promising. Recent functional imaging studies of FM have discovered multiple brain network abnormalities that may provide novel targets for mechanism-based therapies. Future treatment approaches, however, need to improve more than clinical pain but also other FM domains like fatigue, insomnia, and distress.

Autism and chronic ill health: an observational study of symptoms and diagnoses of central sensitivity syndromes in autistic adults

BACKGROUND

Autistic adults, particularly women, are more likely to experience chronic ill health than the general population. Central sensitivity syndromes (CSS) are a group of related conditions that are thought to include an underlying sensitisation of the central nervous system; heightened sensory sensitivity is a common feature. Anecdotal evidence suggests autistic adults may be more prone to developing a CSS. This study aimed to investigate the occurrence of CSS diagnoses and symptoms in autistic adults, and to explore whether CSS symptoms were related to autistic traits, mental health, sensory sensitivity, or gender.

METHODS

The full sample of participants included 973 autistic adults (410 men, 563 women, mean age = 44.6) registered at the Netherlands Autism Register, who completed questionnaires assessing autistic traits, sensory sensitivity, CSS, physical and mental health symptoms. The reliability and validity of the Central Sensitization Inventory (CSI) in an autistic sample was established using exploratory and confirmatory factor analyses. Chi2 analyses, independent t-tests, hierarchical regression and path analysis were used to analyse relationships between CSS symptoms, autistic traits, measures of mental health and wellbeing, sensory sensitivity, age and gender.

RESULTS

21% of participants reported one or more CSS diagnosis, and 60% scored at or above the clinical cut-off for a CSS. Autistic women were more likely to report a CSS diagnosis and experienced more CSS symptoms than men. Sensory sensitivity, anxiety, age and gender were significant predictors of CSS symptoms, with sensory sensitivity and anxiety fully mediating the relationship between autistic traits and CSS symptoms.

LIMITATIONS

Although this study included a large sample of autistic adults, we did not have a control group or a CSS only group. We also could not include a non-binary group due to lack of statistical power.

CONCLUSIONS

CSS diagnoses and symptoms appear to be very common in the autistic population. Increased awareness of an association between autism and central sensitisation should inform clinicians and guide diagnostic practice, particularly for women where CSS are common and autism under recognised.

Review article: current and future treatment approaches for pain in IBS

BACKGROUND

Abdominal pain is a core symptom of IBS and a primary driver of care seeking. Visceral hypersensitivity is a key pathophysiological mechanism and therapeutic target for pain in IBS, with components of peripheral and central sensitisation and psychological factors.

AIM

To review current and future treatment approaches specifically for the pain component of IBS.

METHODS

Pubmed search terms included combinations of irritable bowel, pain, visceral hypersensitivity, novel, new, emerging, future and advances.

RESULTS

Established non-pharmacological treatments for IBS pain include the low FODMAP diet, probiotics and psychological interventions, especially hypnotherapy. Tricyclics remain the best evidenced pharmacological approach with GCC agonists, tenapanor, lubiprostone, eluxadoline and 5HT3 antagonists second line according to patient characteristics and availability. Less well-evidenced current options include anti-spasmodics, peppermint oil, SSRIs, SNRIs, alpha 2 delta ligands, melatonin and histamine antagonists. Patients are vulnerable to iatrogenesis and harmful approaches to be avoided include opioids and unwarranted surgical interventions. For severe pain, the concept of augmentation with combined gut-brain neuromodulators and psychotherapy in a multi-disciplinary setting is considered. A plethora of molecular targets and ligands are emerging from pre-clinical studies, together with early clinical evidence for a range of pharmacological, dietary, neurostimulation and novel psychological treatment delivery methods which are reviewed. The history of such emerging approaches, however, merits both caution and optimism in equal measure.

CONCLUSIONS

Despite good in-roads and emerging options, the management of abdominal pain remains one of the biggest challenges and research priorities for patients with IBS.