Interrogating the Gut-Brain Axis in the Context of Inflammatory Bowel Disease: A Translational Approach

Alleviating depressive-like behavior in DSS-induced colitis mice: Exploring naringin and poncirin from Poncirus trifoliata extracts

Patients with inflammatory bowel diseases (IBDs), including ulcerative colitis (UC) and Crohn's disease (CD), often have concomitant mental disorders such as depression and anxiety. Therefore, a bidirectional approach involving the gut and brain axes is necessary for the prevention and treatment thereof. In this study, we explored the potential of Poncirus trifoliata extract (PT), traditionally known for its neuroprotective effects against gastrointestinal diseases, as a natural treatment agent for IBD in a dextran sulfate sodium (DSS)-induced colitis model. Oral administration of PT ameliorated weight loss and inflammatory responses in mice with DSS-induced colitis. Furthermore, PT treatment effectively restored the colon length and ameliorated enterocyte death by inhibiting DSS-induced reactive oxygen species (ROS)-mediated necroptosis. The main bioactive components of PT, poncirin and naringin, confirmed using ultra-performance liquid chromatography-quadrupole time-of-flight (UPLC-qTOF), can be utilized to regulate necroptosis. The antidepressant-like effects of PT were confirmed using open field test (OFT) and tail suspension test (TST). PT treatment also restored vascular endothelial cell integrity in the hippocampus. In the Cornu Ammonis 1 (CA1) and dentate gyrus (DG) regions of the hippocampus, PT controlled the neuroinflammatory responses of proliferated microglia. In conclusion, PT, which contains high levels of poncirin and naringin, has potential as a bidirectional therapeutic agent that can simultaneously improve IBD-associated intestinal and mental disorders.

Postbiotics: An alternative and innovative intervention for the therapy of inflammatory bowel disease

Inflammatory Bowel Disease (IBD) is a persistent gastrointestinal (GI) tract inflammatory disease characterized by downregulated mucosal immune activities and a disrupted microbiota environment in the intestinal lumen. The involvement of bacterium postbiotics as mediators between the immune system and gut microbiome could be critical in determining why host-microbial relationships are disrupted in IBD. Postbiotics including Short-chain fatty acids (SCFAs), Organic acids, Proteins, Vitamins, Bacteriocins, and Tryptophan (Trp) are beneficial bioactive compounds formed via commensal microbiota in the gut environment during the fermentation process that can be used to improve consumer health. The use of metabolites or fragments from microorganisms can be a very attractive treatment and prevention technique in modern medicine. Postbiotics are essential in the immune system's development since they alter the barrier tightness, and the gut ecology and indirectly shape the microbiota's structure. As a result, postbiotics may be beneficial in treating or preventing various diseases, even some for which there is no effective causative medication. Postbiotics may be a promising tool for the treatment of IBD in individuals of all ages, genders, and even geographical locations. Direct distribution of postbiotics may provide a new frontier in microbiome-based therapy for IBD since it allows both the management of host homeostasis and the correction of the negative implications of dysbiosis. Further studies of the biological effects of these metabolites are expected to reveal innovative applications in medicine and beyond. This review attempts to explore the possible postbiotic-based interventions for the treatment of IBD.

Association between selective serotonin reuptake inhibitor use and developing irritable bowel syndrome through retrospective analysis

BACKGROUND AND AIM

Serotonin affects the balance and integrity of the gut microbiome; however, studies have confirmed the influence of selective serotonin reuptake inhibitors (SSRIs) on irritable bowel syndrome (IBS). We evaluated the association between SSRI use and subsequent IBS occurrence in a real-world setting.

METHODS

A multivariate Cox proportional hazard model was adopted, and the National Health Insurance Service cohort claims database between 2010 and 2019 was used. Non-SSRI users were selected using the propensity score matching method. Subgroup analyses were performed using the point of use, cumulative dose, and duration of SSRI use. Additional analysis was performed using a control group without psychiatric medications.

RESULTS

We included 2901 SSRI users and 2727 non-SSRI users. After adjusting covariates, the risk of developing IBS in SSRI users was 1.54 times that in non-SSRI users (95% confidence interval [CI]: 1.01-2.33). The hazard ratio (HR) of the recent, heavy, and short-term user groups were 3.19 (95% CI: 2.03-4.99), 2.22 (95% CI: 1.50-3.29), and 4.83 (95% CI: 3.02-7.73), respectively, compared with that of non-users. In patients without a history of psychiatric medications, the risk of IBS incidence after SSRI use increased significantly (HR: 1.61, 95% CI: 1.06-2.42), whereas HR was insignificant in patients with a history of psychiatric medications (HR: 1.25, 95% CI: 0.98-1.60).

CONCLUSIONS

The risk of subsequent IBS occurrence following SSRI use was high in patients who initially took a heavy SSRI dose and those who did not have a history of psychiatric drug use.

Depression in Women With Inflammatory Bowel Disease: A Multifaceted Approach for a Multidimensional Problem

The prevalence of depression is higher in patients with inflammatory bowel disease (IBD) than in the general population. Women are more significantly affected by depression among those with IBD and in the general population. This review presents evidence on sex-based differences in depression pathogenesis and the effect of depression on various factors associated with IBD that affect women's lives, including sexual dysfunction, body image dissatisfaction, fertility, and overall quality of life. We also discuss sex-specific effects on IBD treatment, disease activity, and health care costs. Interestingly, women with IBD tend to seek and are more receptive to depression-related information. Given the underdiagnosis and undertreated nature of depression in individuals with IBD, effective screening and an optimal integrative treatment approach with relevant sex-specific needs are discussed. Evidence regarding the efficacy of psychotherapy, antidepressant pharmacotherapy, and IBD-specific therapy for depression is discussed. This review summarizes evidence of the effect of depression on both personal and professional aspects of the daily lives of women with IBD, which extends beyond negative moods. It applies this information to screening and integrative treatment, resulting in a holistic approach to this multidimensional problem. We also discuss how depression affects males with IBD differently from females. Finally, we discuss the need for gender-based studies on depression in individuals with IBD.

Brain signatures of chronic gut inflammation

Gut inflammation is thought to modify brain activity and behaviour via modulation of the gut-brain axis. However, how relapsing and remitting exposure to peripheral inflammation over the natural history of inflammatory bowel disease (IBD) contributes to altered brain dynamics is poorly understood. Here, we used electroencephalography (EEG) to characterise changes in spontaneous spatiotemporal brain states in Crohn's Disease (CD) (n = 40) and Ulcerative Colitis (UC) (n = 30), compared to healthy individuals (n = 28). We first provide evidence of a significantly perturbed and heterogeneous microbial profile in CD, consistent with previous work showing enduring and long-standing dysbiosis in clinical remission. Results from our brain state assessment show that CD and UC exhibit alterations in the temporal properties of states implicating default-mode network, parietal, and visual regions, reflecting a shift in the predominance from externally to internally-oriented attentional modes. We investigated these dynamics at a finer sub-network resolution, showing a CD-specific and highly selective enhancement of connectivity between the insula and medial prefrontal cortex (mPFC), regions implicated in cognitive-interoceptive appraisal mechanisms. Alongside overall higher anxiety scores in CD, we also provide preliminary support to suggest that the strength of chronic interoceptive hyper-signalling in the brain co-occurs with disease duration. Together, our results demonstrate that a long-standing diagnosis of CD is, in itself, a key factor in determining the risk of developing altered brain network signatures.

Enteric Glia and Brain Astroglia: Complex Communication in Health and Disease along the Gut-Brain Axis

Several studies have provided interesting evidence about the role of the bidirectional communication between the gut and brain in the onset and development of several pathologic conditions, including inflammatory bowel diseases (IBDs), neurodegenerative diseases, and related comorbidities. Indeed, patients with IBD can experience neurologic disorders, including depression and cognitive impairment, besides typical intestinal symptoms. In parallel, patients with neurodegenerative disease, such as Parkinson disease and Alzheimer disease, are often characterized by the occurrence of functional gastrointestinal disorders. In this context, enteric glial cells and brain astrocytes are emerging as pivotal players in the initiation/maintenance of neuroinflammatory responses, which appear to contribute to the alterations of intestinal and neurologic functions observed in patients with IBD and neurodegenerative disorders. The present review was conceived to provide a comprehensive and critical overview of the available knowledge on the morphologic, molecular, and functional changes occurring in the enteric glia and brain astroglia in IBDs and neurologic disorders. In addition, our intent is to identify whether such alterations could represent a common denominator involved in the onset of comorbidities associated with the aforementioned disorders. This might help to identify putative targets useful to develop novel pharmacologic approaches for the therapeutic management of such disturbances.

Predicting Neurodegenerative Disease Using Prepathology Gut Microbiota Composition: a Longitudinal Study in Mice Modeling Alzheimer's Disease Pathologies

The gut microbiota-brain axis is suspected to contribute to the development of Alzheimer's disease (AD), a neurodegenerative disease characterized by amyloid-β plaque deposition, neurofibrillary tangles, and neuroinflammation. To evaluate the role of the gut microbiota-brain axis in AD, we characterized the gut microbiota of female 3xTg-AD mice modeling amyloidosis and tauopathy and wild-type (WT) genetic controls. Fecal samples were collected fortnightly from 4 to 52 weeks, and the V4 region of the 16S rRNA gene was amplified and sequenced on an Illumina MiSeq. RNA was extracted from the colon and hippocampus, converted to cDNA, and used to measure immune gene expression using reverse transcriptase quantitative PCR (RT-qPCR). Diversity metrics were calculated using QIIME2, and a random forest classifier was applied to predict bacterial features that are important in predicting mouse genotype. Gene expression of glial fibrillary acidic protein (GFAP; indicating astrocytosis) was elevated in the colon at 24 weeks. Markers of Th1 inflammation (il6) and microgliosis (mrc1) were elevated in the hippocampus. Gut microbiota were compositionally distinct early in life between 3xTg-AD mice and WT mice (permutational multivariate analysis of variance [PERMANOVA], 8 weeks, P = 0.001, 24 weeks, P = 0.039, and 52 weeks, P = 0.058). Mouse genotypes were correctly predicted 90 to 100% of the time using fecal microbiome composition. Finally, we show that the relative abundance of Bacteroides species increased over time in 3xTg-AD mice. Taken together, we demonstrate that changes in bacterial gut microbiota composition at prepathology time points are predictive of the development of AD pathologies. IMPORTANCE Recent studies have demonstrated alterations in the gut microbiota composition in mice modeling Alzheimer's disease (AD) pathologies; however, these studies have only included up to 4 time points. Our study is the first of its kind to characterize the gut microbiota of a transgenic AD mouse model, fortnightly, from 4 weeks of age to 52 weeks of age, to quantify the temporal dynamics in the microbial composition that correlate with the development of disease pathologies and host immune gene expression. In this study, we observed temporal changes in the relative abundances of specific microbial taxa, including the genus Bacteroides, that may play a central role in disease progression and the severity of pathologies. The ability to use features of the microbiota to discriminate between mice modeling AD and wild-type mice at prepathology time points indicates a potential role of the gut microbiota as a risk or protective factor in AD.

Brain, Gut, and Immune Interconnections in Psychiatric Disorders: Implications for Treatment

Recent studies have linked the gut microbiota to psychiatric symptoms and disorders through complex bidirectional networks. The purpose of the current article is to describe the associations between the gut microbiota and brain in psychiatric disorders. Although there are no approved treatments, there are global efforts underway to find more accurate measures to guide treatment and research. In this brief review, we describe current conceptualizations regarding the complex interconnections between psychiatric disorders and the gut microbiota. [Journal of Psychosocial Nursing and Mental Health Services, 61(3), 7-11.].

Electrophysiology as a Tool to Decipher the Network Mechanism of Visceral Pain in Functional Gastrointestinal Disorders

Abdominal pain, including visceral pain, is prevalent in functional gastrointestinal (GI) disorders (FGIDs), affecting the overall quality of a patient's life. Neural circuits in the brain encode, store, and transfer pain information across brain regions. Ascending pain signals actively shape brain dynamics; in turn, the descending system responds to the pain through neuronal inhibition. Pain processing mechanisms in patients are currently mainly studied with neuroimaging techniques; however, these techniques have a relatively poor temporal resolution. A high temporal resolution method is warranted to decode the dynamics of the pain processing mechanisms. Here, we reviewed crucial brain regions that exhibited pain-modulatory effects in an ascending and descending manner. Moreover, we discussed a uniquely well-suited method, namely extracellular electrophysiology, that captures natural language from the brain with high spatiotemporal resolution. This approach allows parallel recording of large populations of neurons in interconnected brain areas and permits the monitoring of neuronal firing patterns and comparative characterization of the brain oscillations. In addition, we discussed the contribution of these oscillations to pain states. In summary, using innovative, state-of-the-art methods, the large-scale recordings of multiple neurons will guide us to better understanding of pain mechanisms in FGIDs.

Association of inflammatory bowel disease with suicidal ideation, suicide attempts, and suicide: A systematic review and meta-analysis

OBJECTIVE

Inflammatory bowel disease (IBD) is associated with psychiatric comorbidities. However, the association between IBD and suicidal ideation or suicide attempts has not been well established. This study aimed to perform a systematic review and meta-analysis to elucidate the relationship between IBD and suicidal ideation, suicide attempts, and suicide.

METHODS

We systematically searched five electronic databases - PubMed, Embase, CENTRAL, Web of Science, and PsycINFO - from their inception to January 28, 2022. Quality assessment, data synthesis, subgroup analyses, sensitivity analyses, and publication bias assessment were performed on the included studies.

RESULTS

We identified 28 studies with 1,047,755 patients with IBD. The pooled prevalence of suicidal ideation in patients with IBD was 17.3% (95% CI, 9.5%-25.2%). Patients with IBD were associated with an increased risk of suicide attempts (relative risk [RR], 1.39; 95% CI, 1.08-1.79) and suicide deaths (RR, 1.25; 95% CI, 1.09-1.43) than the controls without IBD. Patients with Crohn's disease subtypes, female IBD, pediatric-onset IBD, young adult IBD, and short-duration IBD had a particularly high risk for suicide.

CONCLUSION

Patients with IBD had a high prevalence of suicidal ideation and a significantly higher likelihood of suicide attempts and suicide. Caring for patients with IBD, including their mental health needs, may require concerted efforts among gastroenterologists and other healthcare providers.

Measuring Mood and Anxiety Disorders by Patient Reported Outcomes in Inflammatory Bowel Disease: A Literature Review Update

Background Anxiety and depression are the most common psychological disorders found in Inflammatory Bowel Disease (IBD) patients. Accurate measuring of these disorders should be proposed for a prompt management. Patient-reported outcome measurements (PROMs) allow patients to self-report their psychological symptoms. Objective To highlight the presence of PROMs measuring anxiety and depression in IBD setting evaluating the most used psychometric tools. Methods We reviewed the literature from 2010 up to September 2021. Articles on adult IBD patients assessing depression and anxiety by PROMs in English language were included. Results Thirty-six studies, including 11 psychometric tools were found. Hospital Anxiety and Depression Scale (21 studies), Beck Depression Inventory II (5 studies), Spielberg State-Trait Anxiety Inventory (3 studies), Patient-Reported Outcomes Measurement Information System (3 studies), Symptom Checklist-90 (2 studies), Euro Quality of Life (2 studies) mostly used psychometric tools for anxiety and depression in IBD settings. Conclusion Our review analyzed psychometric tools used for PROMs evaluating anxiety and depression in IBD setting. No chronological differences have emerged, all have been used in the last ten years, highlighting a lack of specificity. The strong association between IBD and mood disorders suggests that clinicians should consider the evaluation of depression and anxiety as integral parts of IBD clinical care. It is essential to identify tools enabling these items to be detected better. A global view of IBD patients, accounting not only for physical but also for psychical symptoms with an early and feasible assessment of unrecognized psychiatric disorders, can have a strong impact on their management strategy.

Does Neuroinflammation Underlie the Cognitive Changes Observed With Dietary Interventions?

Dietary interventions, such as calorie restriction and ketogenic diet, have been extensively studied in ageing research, including in cognitive decline. Epidemiological studies indicate beneficial effects of certain dietary regimes on mental health, including mood disorders and dementia. However, randomised-controlled trials (the gold-standard of evidence-based medicine) on calorie restriction diets and the ketogenic diet have yet to show clinically convincing effects in neuropsychiatric disorders. This review will examine the quality of studies and evidence base for the ketogenic and calorie restriction diets in common neuropsychiatric conditions, collating findings from preclinical experiments, case reports or small clinical studies, and randomised controlled clinical trials. The major cellular mechanisms that mediate the effects of these dietary interventions on brain health include neuroinflammation, neuroprotection, and neuromodulation. We will discuss the studies that have investigated the roles of these pathways and their interactions. Popularity of the ketogenic and calorie restriction diets has grown both in the public domain and in psychiatry research, allowing for informed review of the efficacy, the limitations, and the side effects of these diets in specific patient populations. In this review we will summarise the clinical evidence for these diets in neuropsychiatry and make suggestions to improve clinical translation of future research studies.

A Framework for Clinical Trials of Neurobiological Interventions That Target the Gut-Brain Axis in Inflammatory Bowel Disease

A growing body of evidence from preclinical, translational, and clinical studies supports a bidirectional relationship within the gut-brain axis that contributes to neurobiological symptoms including anxiety, depression, fatigue, stress, and sleep disturbance. These symptoms have a significant impact on health-related quality of life and functional ability in individuals with inflammatory bowel disease. Clinical studies that generate high-quality evidence on pharmacological and nonpharmacological (eg, psychosocial, behavioral) interventions are needed to ultimately improve access to safe and effective therapies that have a meaningful impact on patients and to guide medical and regulatory decisions. This review outlines a framework for designing and conducting randomized controlled trials for interventions that target neurobiological symptoms in patients with inflammatory bowel disease based on the most recent guidance published within the past 5 years from policy makers, clinicians specialized in inflammatory bowel disease, patient-reported outcomes methodologists, health economists, patient advocates, industry representatives, ethicists, and clinical trial experts.

Colitis-associated microbiota drives changes in behaviour in male mice in the absence of inflammation

Inflammatory bowel diseases (IBD) are chronic inflammatory conditions of the gastrointestinal tract. IBD are associated with a high prevalence of cognitive, behavioural and emotional comorbidities, including anxiety and depression. The link between IBD and the development of behavioural comorbidities is poorly understood. As the intestinal microbiota profoundly influences host behaviour, we sought to determine whether the altered gut microbiota associated with intestinal inflammation contributes to the development of behavioural abnormalities. Using the dextran sulphate sodium (DSS) model of colitis, we characterized intestinal inflammation, behaviour (elevated plus maze and tail suspension test) and the composition of the microbiota in male mice. Cecal contents from colitic mice were transferred into germ-free (GF) or antibiotic (Abx)-treated mice, and behaviour was characterized in recipient mice. Gene expression was measured using qPCR. DSS colitis was characterized by a significant reduction in body weight and an increase in colonic inflammatory markers. These changes were accompanied by increased anxiety-like behaviour, an altered gut microbiota composition, and increased central Tnf expression. Transfer of the cecal matter from colitic mice induced similar behavioural changes in both GF and Abx-treated recipient mice, with no signs of colonic or neuroinflammation. Upon characterization of the microbiota in donor and recipient mice, specific taxa were found to be associated with behavioural changes, notably members of the Lachnospiraceae family. Behavioural abnormalities associated with intestinal inflammation are transmissible via transfer of cecal matter, suggesting that alterations in the composition of the gut microbiota play a key role in driving behavioural changes in colitis.

The exercise-induced inflammatory response in inflammatory bowel disease: A systematic review and meta-analysis

BACKGROUND

This study investigated selected inflammatory responses to acute and chronic exercise in individuals with inflammatory bowel disease (IBD).

METHODS

A systematic review and meta-analysis was conducted on all relevant exercise-based intervention publications with IBD participants. The study included articles that utilised a broad range of acute and chronic exercise interventions, with inflammatory biomarkers measured and symptoms documented, both pre- and post-exercise for those with IBD. The search was limited to studies published in English, the use of human participants, and primary studies, with no restrictions on date of publication or participant's age. Articles were retrieved through the electronic databases: PubMed, SPORTDiscus, and Scopus. This study adhered to Preferred Reporting Items for Systematic Reviews and Meta-Analysis (PRISMA) guidelines.

RESULTS

Six inflammatory markers were included in the meta-analysis which consisted of five studies. Exercise interventions resulted in no significant difference in IL-6 (SMD = -0.09; 95% CI = -0.49, 0.30; P = 0.64), TNF-α (SMD = 0.08; 95% CI = -0.31, 0.48; P = 0.68), CRP (SMD = -0.04; 95% CI = -0.58, 0.50; P = 0.89), IL-17 (SMD = 0.15; 95% CI = -0.45, 0.76; P = 0.62), leukocytes (SMD = 0.40; 95% CI = -0.53, 1.33; P = 0.40) or lymphocytes (SMD = 0.32; 95% CI = -0.33, 0.97; P = 0.33), thus, indicating exercise may have no effect on inflammatory markers in IBD. Bowel symptoms improved following regular moderate exercise that incorporated stress management.

CONCLUSION

Heterogeneity among the identified literature may have led to exercise interventions being ineffective in reducing inflammation. Although the limited number of eligible studies may reduce the reliability of results, it emphasises the need for additional research in this domain. Importantly, no adverse symptomatic responses to exercise indicate that exercise is safe for IBD patients.

Effects of standard treatments on depressive/anxiety symptoms in patients with inflammatory bowel disease: A systematic review and meta-analysis

OBJECTIVE

A combination of inflammatory bowel disease (IBD) and psychological comorbidities can influence the natural course of IBD. A systematic review and meta-analysis was performed to examine whether a standard IBD medical therapy without any antipsychotic intervention has beneficial effects on depression/anxiety in IBD patients.

METHODS

PubMed and Web of Science databases were systematically searched for related literature from their inception to March 2020. The random-effects model was used to calculate the standardized mean difference (SMD). A total of 16 eligible studies were included in the present meta-analysis.

RESULTS

Compared with baseline assessments, IBD patients with standard IBD medication had significantly reduced depression assessment scores (pooled SMD = 0.500; 95% confidence interval: 0.207, 0.793; P = 0.001). These results were obtained without any psychological interventions. Additionally, no significant differences in anxiety-related scores were detected between the baseline assessments and the end of therapy assessments (pooled SMD = 0.083; 95% confidence interval: -0.120, 0.285; P = 0.425). The meta-regression and subgroup analyses revealed that differences in assessment tools and medications might be the main source of heterogeneity.

CONCLUSION

Standard IBD treatments can significantly alleviate the depressive symptoms in IBD patients. However, more studies are needed to analyze this association.

Clinical health issues, reproductive hormones, and metabolic hormones associated with gut microbiome structure in African and Asian elephants

Background

The gut microbiome is important to immune health, metabolism, and hormone regulation. Understanding host–microbiome relationships in captive animals may lead to mediating long term health issues common in captive animals. For instance, zoo managed African elephants (Loxodonta africana) and Asian elephants (Elephas maximus) experience low reproductive rates, high body condition, and gastrointestinal (GI) issues. We leveraged an extensive collection of fecal samples and health records from the Elephant Welfare Study conducted across North American zoos in 2012 to examine the link between gut microbiota and clinical health issues, reproductive hormones, and metabolic hormones in captive elephants. We quantified gut microbiomes of 69 African and 48 Asian elephants from across 50 zoos using Illumina sequencing of the 16S rRNA bacterial gene.

Results

Elephant species differed in microbiome structure, with African elephants having lower bacterial richness and dissimilar bacterial composition from Asian elephants. In both species, bacterial composition was strongly influenced by zoo facility. Bacterial richness was lower in African elephants with recent GI issues, and richness was positively correlated with metabolic hormone total triiodothyronine (total T3) in Asian elephants. We found species-specific associations between gut microbiome composition and hormones: Asian elephant gut microbiome composition was linked to total T3 and free thyroxine (free T4), while fecal glucocorticoid metabolites (FGM) were linked to African elephant gut microbiome composition. We identified many relationships between bacterial relative abundances and hormone concentrations, including Prevotella spp., Treponema spp., and Akkermansia spp.

Conclusions

We present a comprehensive assessment of relationships between the gut microbiome, host species, environment, clinical health issues, and the endocrine system in captive elephants. Our results highlight the combined significance of host species-specific regulation and environmental effects on the gut microbiome between two elephant species and across 50 zoo facilities. We provide evidence of clinical health issues, reproductive hormones, and metabolic hormones associated with the gut microbiome structure of captive elephants. Our findings establish the groundwork for future studies to investigate bacterial function or develop tools (e.g., prebiotics, probiotics, dietary manipulations) suitable for conservation and zoo management.

Supplementary Information

The online version contains supplementary material available at 10.1186/s42523-021-00146-9.

Altered Brain Structure in Chronic Visceral Pain: Specific Differences in Gray Matter Volume and Associations With Visceral Symptoms and Chronic Stress

Structural brain alterations in chronic pain conditions remain incompletely understood, especially in chronic visceral pain. Patients with chronic-inflammatory or functional bowel disorders experience recurring abdominal pain in concert with other gastrointestinal symptoms, such as altered bowel habits, which are often exacerbated by stress. Despite growing interest in the gut-brain axis and its underlying neural mechanisms in health and disease, abnormal brain morphology and possible associations with visceral symptom severity and chronic stress remain unclear. We accomplished parallelized whole-brain voxel-based morphometry analyses in two patient cohorts with chronic visceral pain, i.e., ulcerative colitis in remission and irritable bowel syndrome, and healthy individuals. In addition to analyzing changes in gray matter volume (GMV) in each patient cohort vs. age-matched healthy controls using analysis of covariance (ANCOVA), multiple regression analyses were conducted to assess correlations between GMV and symptom severity and chronic stress, respectively. ANCOVA revealed reduced GMV in frontal cortex and anterior insula in ulcerative colitis compared to healthy controls, suggesting alterations in the central autonomic and salience networks, which could however not be confirmed in supplemental analyses which rigorously accounted for group differences in the distribution of sex. In irritable bowel syndrome, more widespread differences from healthy controls were observed, comprising both decreased and increased GMV within the sensorimotor, central executive and default mode networks. Associations between visceral symptoms and GMV within frontal regions were altered in both patient groups, supporting a role of the central executive network across visceral pain conditions. Correlations with chronic stress, on the other hand, were only found for irritable bowel syndrome, encompassing numerous brain regions and networks. Together, these findings complement and expand existing brain imaging evidence in chronic visceral pain, supporting partly distinct alterations in brain morphology in patients with chronic-inflammatory and functional bowel disorders despite considerable overlap in symptoms and comorbidities. First evidence pointing to correlations with chronic stress in irritable bowel syndrome inspires future translational studies to elucidate the mechanisms underlying the interconnections of stress, visceral pain and neural mechanisms of the gut-brain axis.

The role of gut and genital microbiota and the estrobolome in endometriosis, infertility and chronic pelvic pain

BACKGROUND

Endometriosis is a chronic, burdensome condition that is historically understudied. Consequently, there is a lack of understanding of the etiology of the disease and its associated symptoms, including infertility and chronic pelvic pain (CPP). Endometriosis development is influenced by estrogen metabolism and inflammation, which are modulated by several factors including the microbiome and the estrobolome (the collection of genes encoding estrogen-metabolizing enzymes in the gut microbiome). Therefore, there is increasing interest in understanding the role of microbiota in endometriosis etiology.

OBJECTIVE AND RATIONALE

To date, there is no cure for endometriosis and treatment options often are ineffective. This manuscript will review the potential relationship between the microbiome and endometriosis, infertility and CPP and highlight the available data on the microbiome in relation to endometriosis and its related symptoms. The overarching goal of this manuscript is to inform future microbiome research that will lead to a deeper understanding of the etiology of the disease and possible diagnostic modalities and treatments. The potential impact of the microbiome on estrogen regulation modulated by the estrobolome, as well as inflammation and other endometriosis-promoting mechanisms within the genital tract, will be reviewed. The methodological limitations of microbiome-related studies will be critically assessed to provide improved guidelines for future microbiome and clinical studies.

SEARCH METHODS

PubMed databases were searched using the following keywords: endometriosis AND microbiome, infertility AND microbiome, pelvic pain AND microbiome, IVF (in-vitro fertilization) AND microbiome, endometriosis AND infertility. Clinical and preclinical animal trials that were eligible for review, and related to microbiome and endometriosis, infertility or CPP were included. All available manuscripts were published in 2002-2021.

OUTCOMES

In total, 28 clinical and 6 animal studies were included in the review. In both human and animal studies, bacteria were enriched in endometriosis groups, although there was no clear consensus on specific microbiota compositions that were associated with endometriosis, and no studies included infertility or CPP with endometriosis. However, bacterial vaginosis-associated bacteria and Lactobacillus depletion in the cervicovaginal microbiome were associated with endometriosis and infertility in the majority (23/28) of studies. Interpretation of endometrial studies is limited owing to a variety of methodological factors, discussed in this review. In addition, metadata outlining antibiotic usage, age, race/ethnicity, menopausal status and timing of sample collection in relation to diagnosis of endometriosis was not consistently reported. Animal studies (6/6) support a bidirectional relationship between the gut microbiota and endometriosis onset and progression.

WIDER IMPLICATIONS

There is evidence that a dysbiotic gut or genital microbiota is associated with multiple gynecologic conditions, with mounting data supporting an association between the microbiome and endometriosis and infertility. These microbiomes likely play a role in the gut-brain axis, which further supports a putative association with the spectrum of symptoms associated with endometriosis, including infertility and CPP. Collectively, this review highlights the demand for more rigorous and transparent methodology and controls, consistency across the field, and inclusion of key demographic and clinical characteristics of disease and comparison participants. Rigorous study designs will allow for a better understanding of the potential role of the microbiome in endometriosis etiology and the relationship to other disorders of the female reproductive tract.

Health-related quality of life in youth with abdominal pain: An examination of optimism and pain self-efficacy

OBJECTIVES

Abdominal pain adversely impacts children with functional gastrointestinal disorders (FGIDs) or organic gastrointestinal disorders (OGIDs); findings are inconsistent regarding diagnosis and health-related quality of life (HRQoL). This study utilizes a positive psychology framework to understand the experience of youth with abdominal pain (i.e., do positive psychological factors, such as optimism and pain self-efficacy, relate to higher HRQoL?). Consistent with a protective factor model of resilience, in which personal assets may serve as buffers between risk factors and negative outcomes, optimism and pain self-efficacy were examined as they relate to HRQoL in youth with abdominal pain. Specifically, exploratory moderational analyses examined a) if optimism and pain self-efficacy moderate the relation between pain and HRQoL, and b) whether diagnostic status moderated the relation between optimism/pain self-efficacy and HRQoL.

METHODS

In a cross-sectional, observational study, youth (n = 98; M_age = 13, SD = 3) experiencing abdominal pain related to FGIDs or OGIDs and one of their parents participated. Measures included pain intensity, optimism, pain self-efficacy, and HRQoL. Analyses controlled for diagnosis, age, and gender.

RESULTS

Higher pain and age related to lower HRQoL. Higher levels of optimism and pain self-efficacy associated with HRQoL beyond demographics. Optimism and pain self-efficacy did not moderate the relation between pain and HRQoL. Diagnostic status did not moderate the relation between optimism or pain self-efficacy and HRQoL.

DISCUSSION

Our results suggest positive relations between positive psychological factors (optimism, pain self-efficacy) and HRQoL in youth with abdominal pain. Such factors could be further examined in intervention studies.

Gastrointestinal side effects associated with antidepressant treatments in patients with major depressive disorder: A systematic review and meta-analysis

Gastrointestinal side effects (SEs) are frequently observed in patients with major depressive disorder (MDD) while taking antidepressants and may lead to treatment discontinuation. The aim of this meta-analysis is to provide quantitative measures on short-term rates of gastrointestinal SEs in MDD patients treated with second-generation antidepressants. An electronic search of the literature was conducted by using MEDLINE, ISI Web of Science - Web of Science Core Collection, and Cochrane Library databases. Eligible studies had to focus on the use of at least one of 15 antidepressants commonly used in MDD (i.e., agomelatine, bupropion, citalopram, desvenlafaxine, duloxetine, escitalopram, fluoxetine, fluvoxamine, levomilnacipran, mirtazapine, paroxetine, reboxetine, sertraline, venlafaxine, and vortioxetine) and report data on treatment-emergent gastrointestinal SEs (i.e. nausea/vomiting, diarrhoea, constipation, abdominal pain, dyspepsia, anorexia, increased appetite and dry mouth) within 12 weeks of treatment. Overall, 304 studies were included in the meta-analyses. All the considered antidepressants showed higher rates of gastrointestinal SEs than placebo. Escitalopram and sertraline were shown to be the least tolerated antidepressants on the gastrointestinal tract, being associated with all the considered SEs with the exception of constipation and increased appetite, while mirtazapine was shown to be the antidepressant with fewer side effects on the gut, being only associated with increased appetite. In conclusion, commonly used antidepressants showed different profiles of gastrointestinal SEs, possibly related to their mechanisms of action. The specific tolerability profile of each compound should be considered by clinicians when prescribing antidepressants in order to improve adherence to treatment and increase positive outcomes in patients with MDD.

Stress and the Gut-Brain Axis: Implications for Cancer, Inflammation and Sepsis

BACKGROUND

The gut-brain axis has been discussed, directly or indirectly, for centuries, with the ideas of the gut affecting anything from moods to overall physiology being discussed across the centuries. With a recent explosion in research that looks to the microbiota as a mechanistic link between the gut and the brain, one sees that the gut-brain axis has various means of communication, such as through the vagus nerve and the enteric nervous system and can use the metabolites in the gut to communicate to the brain.

METHODS

The purpose of this review is to view the gut-brain axis through the lens of stress and how stress, from the prenatal period all the way through adulthood can impact the physiology of a human being. Studies have shown multiple mechanisms of measurable change with disruption in the microbiota that lead to behavioral changes. There are also effects of gut inflammation on the brain and the corresponding systemic response observed.

CONCLUSION

The overall literature is encouraging that the more understanding of the gut-brain axis, the greater ability to wield that understanding for therapeutic benefits.

The brain-gut axis, inflammatory bowel disease and bioelectronic medicine

The hallmark of inflammatory bowel diseases (IBD) is chronic intestinal inflammation with typical onset in adolescents and young adults. An abundance of neutrophils is seen in the inflammatory lesions, but adaptive immunity is also an important player in the chronicity of the disease. There is an unmet need for new treatment options since modern medicines such as biological therapy with anti-cytokine antibodies still leave a substantial number of patients with persisting disease activity. The role of the central nervous system and its interaction with the gut in the pathophysiology of IBD have been brought to attention both in animal models and in humans after the discovery of the inflammatory reflex. The suggested control of gut immunity by the brain-gut axis represents a novel therapeutic target suitable for bioelectronic intervention. In this review, we discuss the role of the inflammatory reflex in gut inflammation and the recent advances in the treatment of IBD by intervening with the brain-gut axis through bioelectronic devices.

Buspirone alleviates anxiety, depression, and colitis; and modulates gut microbiota in mice

Gut microbiota regulate the neurodevelopmental processes and brain functions through the regulation of the microbiota–gut interaction and gut–brain communication. Buspirone, an agonist for serotonin 5-HT1A receptors, is used for the treatment of anxiety/depression. Therefore, to understand the gut microbiota-mediated mechanism of buspirone on anxiety/depression, we examined its effect on the immobilization stress (IS) or Escherichia coli K1 (EC)-induced anxiety/depression in mice. Oral or intraperitoneal administration of buspirone significantly suppressed stressor-induced anxiety/depression-like behaviors in the elevated plus maze, light/dark transition, tail suspension, and forced swimming tasks. Their treatments also reduced TNF-α expression and NF-κB⁺/Iba1⁺ cell population in the hippocampus and myeloperoxidase activity and NF-κB⁺/CD11c⁺ cell population in the colon. Buspirone treatments partially restored IS- or EC-induced gut microbiota perturbation such as β-diversity to those of normal control mice: they reduced the IS- or EC-induced gut Proteobacteria population. In particular, the anxiolytic activity of buspirone was positively correlated with the populations of Bacteroides and PAC001066_g in EC- or IS-exposed mice, while the populations of Lachnospiraceae, KE159660_g, LLKB_g, Helicobacter, and PAC001228_g were negatively correlated. The anti-depressant effect of buspirone was positively correlated with the Roseburia population. The fecal microbiota transplantations from buspirone-treated mice with IS-induced anxiety/depression or normal control mice suppressed IS-induced anxiety/depression-like behaviors and reduced hippocampal NF-κB⁺/Iba1⁺ and colonic NF-κB⁺/CD11c⁺ cell populations in the transplanted mice. Furthermore, they modified IS-induced perturbation of gut microbiota composition, particularly Proteobacteria, in the transplanted mice. In conclusion, buspirone alleviates IS as well as EC-induced anxiety/depression and colitis. It also suppresses associated neuroinflammation and modulates gut microbiota. Future studies can help to explain the relationship, if any, in the central and peripheral effects of buspirone.

Association Between Inflammatory Bowel Disease and Psychiatric Morbidity and Suicide: A Swedish Nationwide Population-Based Cohort Study With Sibling Comparisons

BACKGROUND AND AIMS

Inflammatory bowel disease [IBD] is linked to psychiatric morbidity, but few studies have assessed general population comparators. We aimed to investigate the risk of psychiatric morbidity and suicide in adult-onset IBD patients.

METHODS

We used a nationwide population-based cohort study in Sweden [1973-2013]. We studied the risk of psychiatric disorders and suicide in 69,865 adult-onset IBD patients [ulcerative colitis, UC: n = 43,557; Crohn's disease, CD: n = 21,245; and IBD-unclassified: n = 5063] compared to 3,472,913 general population references and 66 292 siblings.

RESULTS

During a median follow-up of 11 years, we found 7465 [10.7%] first psychiatric disorders in IBD [incidence rate, IR/1000 person-years 8.4] and 306 911 [9.9%] in the general population [IR 6.6], resulting in 1.8 extra psychiatric morbidity per 100 patients followed-up for 10 years and a hazard ratio [HR] of 1.3 [95% confidence interval, 95%CI = 1.2-1.3]. The highest risk of overall psychiatric morbidity was seen in the first year after IBD diagnosis [HR = 1.4, 95%CI = 1.2-1.6] and in patients with extraintestinal manifestations [HR = 1.6, 95%CI = 1.5-1.7]. Psychiatric morbidity was more common in all IBD subtypes [HR 1.3-1.5]. An increased risk of suicide attempts was observed among all IBD types [HR = 1.2-1.4], whereas completed suicide was explicitly associated with CD [HR = 1.5] and elderly-onset [diagnosed at the age of > 60 years] IBD [HR = 1.7].

CONCLUSION

Adult-onset IBD was associated with an increased risk of psychiatric disorders and suicide attempts. Psychological follow-up should be provided to patients with IBD, especially those with extraintestinal manifestations and elderly-onset IBD. This follow-up should be within the first year after IBD diagnosis.

The Brain-Gut Axis: Psychological Functioning and Inflammatory Bowel Diseases

The brain-gut axis represents a complex bi-directional system comprising multiple interconnections between the neuroendocrine pathways, the autonomous nervous system and the gastrointestinal tract. Inflammatory bowel disease (IBD), comprising Crohn's disease and ulcerative colitis, is a chronic, relapsing-remitting inflammatory disorder of the gastrointestinal tract with a multifactorial etiology. Depression and anxiety are prevalent among patients with chronic disorders characterized by a strong immune component, such as diabetes mellitus, cancer, multiple sclerosis, rheumatoid arthritis and IBD. Although psychological problems are an important aspect of morbidity and of impaired quality of life in patients with IBD, depression and anxiety continue to be under-diagnosed. There is lack of evidence regarding the exact mechanisms by which depression, anxiety and cognitive dysfunction may occur in these patients, and whether psychological disorders are the result of disease activity or determinants of the IBD occurrence. In this comprehensive review, we summarize the role of the brain-gut axis in the psychological functioning of patients with IBD, and discuss current preclinical and clinical data on the topic and therapeutic strategies potentially useful for the clinical management of these patients. Personalized pathways of psychological supports are needed to improve the quality of life in patients with IBD.

Heart rate variability and inflammatory bowel disease in humans: A systematic review and meta-analysis

The autonomic nervous system (ANS) maintains homeostasis in the gastrointestinal tract, including immunity, inflammation and motility, through the brain-gut axis. To date, the associations between ANS function and inflammatory bowel disease (IBD) have been controversial and inconclusive in human studies. PubMed, Cochrane Library, and Embase were searched through February 2020 for articles reporting these association between heart rate variability (HRV), an indirect measure of ANS activity, and IBD. The standardized mean differences and 95% confidence intervals (CIs) were calculated. Ten eligible studies involving 273 ulcerative colitis patients, 167 Crohn's disease patients and 208 healthy controls were included. The values of the total power (SMD = -0.83, 95% CI = -1.44, -0.21), high frequency (SMD = -0.79, 95% CI = -1.20, -0.38), RR interval (SMD = -0.66, 95% CI = -1.04, -0.27), standard deviation of the RR intervals (SMD = -1.00, 95% CI = -1.73, -0.27), percentage of RR intervals with a greater than 50-millisecond variation (SMD = -0.82, 95% CI = -1.33, -0.30) and the square root of the mean squared differences in successive RR intervals (SMD = -0.71, 95% CI = -1.15, -0.26) of the IBD patients were lower than those of the healthy controls, and moderate to large effect sizes were observed in all HRV indices, except for low frequency (SMD = -0.41, 95% CI = 0.95, 0.13). IBD was strongly associated with an overall decrease in HRV, indicating substantially decreased ANS activity. Furthermore, the parasympathetic nerve displayed a stronger inverse association with ANS activity than the sympathetic nerve, indicating ANS dysfunction in patients with IBD.