The Gut-Immune-Brain Axis: An Important Route for Neuropsychiatric Morbidity in Inflammatory Bowel Disease

Mechanism of Wuling powder modulating proBDNF/p75NTR/sortilin and BDNF/TrkB pathways in the treatment of ulcerative colitis complicated with depression

BACKGROUND

Ulcerative colitis (UC) is a chronic inflammatory disease affecting the colon. The most common psychological issue in UC patients is varying degrees of depression, which affects the condition and quality of life of UC patients and may lead to deterioration of the patient’s condition. UC drugs combined with antianxiety and antidepression drugs can alleviate symptoms of both depression and UC. Brain-derived neurotrophic factor (BDNF) precursor (proBDNF)/p75 neurotrophin receptor (p75NTR)/sortilin and BDNF/tropomyosin receptor kinase B (TrkB) signalling balance is essential for maintaining brain homeostasis and preventing the development of depressive behaviours.

AIM

To explore the mechanism by which Wuling powder regulates the proBDNF/p75NTR/sortilin and BDNF/TrkB pathways in the treatment of UC with depression.

METHODS

Depression was established in C57BL/6J mice via chronic restraint stress, and the UC model was induced with dextran sodium sulfate (DSS). In the treatment stage, mesalazine (MS) was the basic treatment, Wuling powder was the experimental treatment, and fluoxetine was the positive control drug for treating depression. Changes in intestinal mucosal inflammation, behaviour, and the proBDNFp75NTR/sortilin and BDNF/TrkB pathways were evaluated.

RESULTS

In the depression groups, Wuling powder decreased the immobility time, increased the distance travelled in the central zone and the total distance travelled, and restored balance in the proBDNF/p75NTR/sortilin and BDNF/TrkB signalling pathways. In the DSS and chronic restraint stress + DSS groups, immobility time increased, distance travelled in the central zone and total distance travelled decreased, activity of the proBDNF/p75NTR/sortilin pathway was upregulated, and activity of the BDNF/TrkB pathway was downregulated, indicating that mice with UC often have comorbid depression. Compared with those of MS alone, Wuling powder combined with MS further decreased the colon histopathological scores and the expression levels of tumor necrosis factor-alpha and interleukin-6 mRNAs.

CONCLUSION

This study confirmed that Wuling powder may play an antidepressant role by regulating the balance of the proBDNF/p75NTR/sortilin and BDNF/TrkB signalling pathways and further relieve intestinal inflammation in UC.

Research progress on edible mushroom polysaccharides as a novel therapeutic strategy for inflammatory bowel disease

Inflammatory bowel disease (IBD) is a complex condition linked to the gut microbiota, host metabolism, and the immune system. Edible mushroom polysaccharides (EMPs) are gaining attention for their benefits, particularly as prebiotics that help balance gut microbial, a key factor in IBD. With their scalable production, diverse hydrophilic properties, and demonstrated anti-inflammatory effects in both laboratory and animal studies, EMPs show promise for easing IBD symptoms. By supporting a healthy gut microbiome through various mechanisms, EMPs can play an important role in preventing and managing IBD, ultimately benefiting overall health and opening new treatment avenues. This review examines how EMPs affect IBD, focusing on their role in shaping gut microbiota, restoring gut barriers, regulating immune function, and influencing pathways related to colitis. It also explores their impact on the microbiota-gut-multi organ axis and overall host health, as well as the relationship between EMPs preparation, structure, and bioactivity, along with their potential applications in food and medicine. This investigation provides valuable insights into the intricate connections between the gut, immune system, and systemic inflammation system, highlighting how EMPs are key players in this complex interaction.

Dual Role of α-MSH in Colitis Progression: Mediating Neutrophil Differentiation via Bone Marrow

Background

Inflammatory bowel disease (IBD) comprises a group of autoimmune disorders characterized by chronicity and resistance to cure, with an unknown etiology. Recent studies on the brain-gut axis suggest that the central nervous system (CNS), particularly the hypothalamic-pituitary axis (HPA), may play a crucial role in modulating the immune system and influencing disease progression. However, the specific role and mechanism of the HPA in IBD pathogenesis remain unclear. This study aims to investigate the alterations in the HPA and its potential roles during IBD development.

Methods

We utilized a dextran sodium sulfate (DSS)-induced colitis model in mice and employed immunofluorescence, real-time quantitative PCR (RT-qPCR), enzyme-linked immunosorbent assay (ELISA), among other techniques, to evaluate the impact of colitis on the HPA. Additionally, we used flow cytometry, adeno-associated virus-mediated gene silence, parabiosis and single-cell RNA sequencing to uncover the specific roles and mechanisms of the HPA in colitis.

Results

Our results indicate that colitis activates HPA secretion and increases α-MSH. α-MSH acts on the MC5R present on the surface of hematopoietic stem cells (HSCs) in the bone marrow, altering the bone marrow microenvironment and promoting HSCs proliferation and differentiation into neutrophils. This process enhances the clearance of pathogenic microorganisms during the acute phase of colitis, while inducing sustained inflammatory responses during the remission phase.

Conclusion

In summary, our study demonstrates the dual role of HPA activation and α-MSH secretion induced by colitis in the pathogenesis of IBD. These findings offer vital guidance for optimizing personalized treatment of IBD, emphasizing the importance of carefully managing the timing and dosage of α-MSH for its effective clinical application.

Neuroprotective role of mirabegron: Targeting beta-3 adrenergic receptors to alleviate ulcerative colitis-associated cognitive impairment

While cognitive impairment has been documented in ulcerative colitic patients, the possible influence of central β3-adrenergic receptor (β3-AR) signaling on this extraintestinal manifestation remains unclear. Previously, we identified an imperative role for mirabegron (MA) as an agonist of β3-AR, in decreasing the BACE-1/beta-amyloid (Aβ) cue in the colons of UC rats. Consequently, we investigated its therapeutic potential for alleviating cognitive impairment associated with UC. To fulfil our aim, rats administered iodoacetamide were treated with the β3-AR agonist (MA) alone, with the antagonist (SR59230A) for 8 days, or kept untreated. The animals' behavior (MWM and NOR tests) and hippocampal structure were assessed. Mechanistically, necroptosis, ER stress (ERS), Aβ-amyloidosis, inflammation/oxidative burden, and gut/BBB dysfunction were analyzed. Post-administration of MA improved weight gain, colon/hippocampal structures, and memory. Additionally, it inhibited serum levels of lipopolysaccharide and Annexin-1, indicating recovered gut and BBB integrity. MA turned off the pathogenic BACE-1/Aβ axis in the hippocampus, necroptosis trajectory (TNFR-1/RIPK1/RIPK3/MLKL), and the IRE-1α/JNK signal. Moreover, MA enhanced the transcription factor PPAR-γ, decreased NF-κΒ/TNF-α inflammatory hub, and modulated the redox imbalance by decreasing malondialdehyde and increasing catalase. Notably, MA's behavioral, structural, and molecular beneficial actions were hindered by the pre-administration of SR59230A. From a novel standpoint, we recognized the β3-AR as a therapeutic target for UC-associated cognitive impairment in the hippocampus. In this context, the aptitude of MA to inhibit UC-induced hippocampal amyloidogenesis, alongside its anti-necroptotic, anti-ERS, anti-inflammatory, and antioxidant effects, contribute to these central enhancements, while also regulating permeability in both gut and BBB barriers.

Milk-derived extracellular vesicles and gut health

Milk is a nutrient-rich liquid produced by mammals, offering various health benefits due to its composition of proteins, fats, carbohydrates, vitamins, and minerals. Beyond traditional nutritional aspects, recent research has focused on extracellular vesicles (EVs) found in milk and their potential health benefits, especially for gastrointestinal (GI) health. Milk-derived EVs have been shown to influence gut microbiota, promote gut barrier integrity, support tissue repair and regeneration, modulate immune responses, and potentially aid in managing conditions like inflammatory bowel disease (IBD) and colorectal cancer. This review discusses the current understanding of milk-EVs' effects on gut health, highlighting their potential therapeutic applications and future research directions. These findings underscore the promising role of milk-derived EVs in advancing GI health and therapeutics, paving the way for innovative approaches in oral drug delivery and targeted treatments for GI disorders.

Neuroprotective effects of whey and buttermilk-based formulas on a DSS-induced colitis murine model

Inflammatory bowel disease is a gut-brain axis disorder that comprises chronic inflammatory conditions affecting the gastrointestinal tract, where alterations in the mood of patients are common. Gut-brain axis is a bidirectional communication that link gut and brain. The close association between inflammatory bowel disease and neuroinflammation has far-reaching implications, as is increasingly recognized as a contributing factor to neuropsychiatric and neurodegenerative diseases. The increasing prevalence and high economic cost, together with the loss of life quality of people suffering from these diseases, point to the need to find alternatives to alleviate them. Exploring new therapeutic avenues prompts us to consider the potential benefits of milk fractions, taking advantage of the use of dairy by-products, such as whey and buttermilk. This study examines the impact of cow's whey- and buttermilk-based formulas supplemented with bovine lactoferrin and milk fat globule membrane on the expression of cytokines, as well as on the components of immune and serotonergic system of the brain in a murine model of dextran sodium sulfate-induced colitis. Our results show the potential of these dairy by-products, especially whey, as functional foods in ameliorating neuroinflammation and safeguarding the central nervous system function amid the neurological complications induced or concomitant with intestinal inflammatory processes.

Altered Function and Structure of the Cerebellum Associated with Gut-Brain Regulation in Crohn's Disease: a Structural and Functional MRI Study

This study employed structural and functional magnetic resonance imaging (MRI) to investigate changes in the function and structure of the cerebellum associated with gut-brain axis (GBA) regulation in patients diagnosed with Crohn's disease (CD). The study comprised 20 CD patients, including 12 with active disease (CD-A) and 8 in remission (CD-R), as well as 21 healthy controls. Voxel-based morphometry (VBM) was utilized for structural analysis of cerebellar gray matter volume, while independent component analysis (ICA) was applied for functional analysis of cerebellar functional connectivity (FC). The results showed significant GMV reduction in the left posterior cerebellar lobe across all CD patients compared to HCs, with more pronounced differences in the CD-A subgroup. Additionally, an increase in mean FC of the cerebellar network was observed in all CD patients, particularly in the CD-A subgroup, which demonstrated elevated FC in the vermis and bilateral posterior cerebellum. Correlation analysis revealed a positive relationship between cerebellar FC and the Crohn's Disease Activity Index (CDAI) and a trend toward a negative association with the reciprocal of the Self-rating Depression Scale (SDS) score in CD patients. The study's findings suggest that the cerebellum may play a role in the abnormal regulation of the GBA in CD patients, contributing to a better understanding of the neural mechanisms underlying CD and highlighting the cerebellum's potential role in modulating gut-brain interactions.

State-specific GluCEST alterations in insular subregions are associated with depression and plasma inflammatory biomarker levels in patients with inflammatory bowel disease

BACKGROUND

Depression commonly co-occurs with inflammatory bowel disease (IBD). Abnormal glutamate levels in the insula and altered plasma inflammatory biomarkers are observed in IBD and depression. However, the changes in glutamate concentrations in insular subregions in IBD and their relationship with depression and inflammatory markers remain unclear. This study aimed to investigate differences in glutamate concentrations in insular subregions between IBD patients and healthy controls (HCs) and their correlation with depression scores and inflammatory markers.

METHODS

Forty-two IBD patients (19 active, IBD-A; 23 in remission, IBD-R) and 46 HCs underwent glutamate chemical exchange saturation transfer (GluCEST) magnetic resonance imaging. Blood samples from 37 IBD patients were collected for plasma inflammatory biomarker analysis. GluCEST indices in insular subregions were measured. The Hospital Anxiety and Depression Scale (HADS-D) was used to estimate depression symptoms. Whole-brain voxel-based analysis using one-way ANOVA explored between-group differences in GluCEST indices within the insula. FDR-corrected partial correlation analysis evaluated the relationships between GluCEST, depression symptoms, and inflammatory factors.

RESULTS

GluCEST indices decreased in IBD patients in the left dorsal dysgranular subregion of the insula (dId) (uncorrected p < 0.001, cluster-level FWE-corrected p < 0.05). GluCEST indices in the left dId showed a significant positive correlation with HADS-D in IBD-R (FDR corrected q < 0.05). Additionally, GluCEST indices in the left dId were negatively correlated with CXCL9 (FDR corrected q < 0.05).

CONCLUSION

State-specific GluCEST alterations in the left dId are a cerebral metabolic feature of IBD. These changes are associated with depression and inflammatory biomarkers, suggesting that the brain-immune-gut axis might underlie depression in IBD patients.

Abdominal ultrasound stimulation alleviates DSS-induced colitis and behavioral disorders in mice by mediating the microbiota-gut-brain axis balance

Inflammatory bowel disease (IBD) has the potential to induce neuroinflammation, which may increase the risk of developing neurodegenerative disorders. Ultrasound stimulation to the abdomen is a potential treatment for dextran sulfate sodium (DSS)-induced acute colitis. The present study aimed to investigate whether abdominal low-intensity pulsed ultrasound (LIPUS) can alleviate DSS-induced neuroinflammation through the microbiota-gut-brain axis. Male mice were fed DSS to induce ulcerative colitis. LIPUS stimulation was then applied to the abdomen at intensities of 0.5 and 1.0 ​W/cm2. Mouse biological samples were analyzed, and behavior was evaluated. [18F]FEPPA PET/CT imaging was employed to track and quantify inflammation in the abdomen and brain. Changes in the gut microbiota composition were analyzed using 16S rRNA sequencing. Abdominal LIPUS significantly inhibited the DSS-induced inflammatory response, repaired destroyed crypts, and partially preserved the epithelial barrier. [18F]FEPPA accumulation in the colitis-induced neuroinflammation in the abdomen and specific brain regions significantly decreased after LIPUS treatment. LIPUS maintained intestinal integrity by increasing zonula occludens and occludin levels, reduced lipopolysaccharide-binding protein and lipopolysaccharide levels in the serum, and improved behavioral dysfunctions. Moreover, LIPUS, at an intensity of 0.5 ​W/cm2, reshaped the gut microbiota in colitis-induced mice by increasing the relative abundance of the Firmicutes and decreasing the relative abundance of the Bacteroidota. Our findings demonstrated that abdominal LIPUS stimulation has the potential to be a novel therapeutic strategy to improve colitis-induced behavioral disorders through microbiota-gut-brain axis signaling.

Experimental colitis is comorbid with social interaction deficits and anxiety-like behaviors in mice: mechanistic intuitions into neuroinflammation and Claudin 5 expression in the hippocampus

Inflammatory bowel disease (IBD) is accompanied by psychiatric disorders, including Schizophrenic-like manifestations. Although incompletely illustrated, intestinal mucosal membrane damage and blood-brain barrier (BBB) penetrability may have significant roles in psychiatric symptoms of IBD. This study aimed to investigate role of the Claudin-5 (CLDN5) (a regulator of the permeability of BBB) and neuroinflammatory response in the comorbid behavioral disorders in experimental colitis in mice. Acetic acid was used to induce colitis in mice. 7 days after induction of colitis, behaviors including social interaction and locomotor activity as well as anxiety-like behaviors were evaluated. Then, the colon was extracted for gross and microscopic evaluations. The expression of CLDN5, TNF-α, IL1β and IL23 was measured by RT-PCR in the colon and hippocampus. Histopathologic evaluations demonstrated mucosal, submucosal, and crypt-related damages in the colon. The negative and positive number of social interactions significantly increased in the colitis group. A considerable increase in locomotor activities (horizontal and vertical components) shown in the colitis group. Mice in colitis group spent less time in the central zone in the open field apparatus. Gene expressions of TNF-α, IL1β, and IL23 increased and CLDN5 decreased in the colitis group. The barrier function of the intestine and brain would be impaired, partially at least, following colitis (as we observed decrease in CLDN5 gene expression). Furthermore, we found that beside inflammatory response in the colon, a neuro-immune response triggered in the hippocampus following colitis. These alterations probably, mediated comorbid behavioral disorders in acetic acid-induced colitis in mice.

Motor, mood, and memory impairments persist during remission periods in chronic colitis and are influenced by neuroinflammation and sex

Ulcerative colitis is a chronic pathology characterized by relapsing-remitting phases of intestinal inflammation. Additionally, some patients develop neuropsychiatric disorders, such as depression and anxiety, or cognitive deficits. We aimed to investigate whether the development of chronic colitis elicits memory, locomotion, and mood impairments. It further examined whether these impairments are influenced by the relapsing-remitting phases of the colitis or by sex. Here, we used a chronic colitis model in male and female rats, induced with sodium dextran sulfate, mirroring the phases of human ulcerative colitis. Our results revealed that the severity of colitis was slightly higher in males than females. Chronic colitis triggered motor and short-term memory deficits and induced anxiety- and depression-like behaviors that remained throughout the development of the disease. There are also sex differences under control or inflammatory conditions. Therefore, in both situations, females compared to males displayed: (i) slightly lower locomotion, (ii) increased anxiety-like behaviors, (iii) similar depression-like behaviors, and (iv) similar short-term memory deficit. Additionally, under control conditions, the mRNA levels of IL-1β, IL-6, and TNF-α were higher in the female hippocampus. In both sexes, when chronic colitis was established, the neuroinflammation was evidenced by increased mRNA levels of these three cytokines in the hippocampus and in the motor and prefrontal cortices. Interestingly, this neuroinflammation was slightly greater in males. In summary, we show that the development of chronic colitis caused persistent behavioral abnormalities, highlighting sex differences, and that could be a consequence, at least in part, of the increase in IL-1β, IL-6, and TNF-α in the brain.

A Comprehensive Review of Coptidis Rhizoma and Magnoliae Officinalis Cortex Drug Pair and Their Chemical Composition, Pharmacological Effects and Pharmacokinetics Analysis

Herbal pairs are unique combinations of two relatively fixed herbs that are used in clinical practice. This is the most fundamental and straightforward form of multiple herbal treatment that aims to attain specific efficacy through unique methods. Coptidis Rhizoma ("Huanglian" in Chinese) and Magnoliae Officinalis Cortex ("Houpo" in Chinese) which are commonly used in combination and could also be used as important components of other prescriptions to treat damp-heat dysentery, splenic and stomach disorders, and qi stagnation in clinical practice. However, there is currently no summary on the compatibility of Huanglian and Houpo about traditional use, phytochemistry, and pharmacological activity. It was found the combination or separate extraction of the two drugs may affect the main active components, and new components may be produced after the combined extraction. At the same time, Huanglian and Houpo herb pair exhibited antiviral, anti-inflammatory, antibacterial and other pharmacological effects. At present, research mainly focuses on the indicator components of Huanglian and Houpo, such as berberine, magnolol, and magnolol. The models used for pharmacological validation are limited, mainly including ulcerative colitis, pneumonia, bacterial infections, etc. In order to verify the pharmacological activity of the combination of Huanglian and Houpo, it is necessary to try more in vitro and in vivo models. It's still need to study the compatibility mechanism of the Huanglian and Houpo drug pair, including but not limited to the interactions between different components and the impact of compatibility on efficacy, bioequivalence studies, and the impact of different dosage forms on pharmacokinetics in the future. It's believed that the systematic review provided comprehensive information for the study of Huanglian-Houpo drug pair, which will help highlight the importance of the Huanglian-Houpo herb pair and provide some clues for future research on this herb pair.

Exploring the Therapeutic Potential of Terpenoids for Depression and Anxiety

This review focus on the terpenoids as potential therapeutic agents for depression and anxiety disorders, which naturally found in a variety of plants and exhibit a wide range of biological activities. Among the terpenoids discussed in this review are α-pinene, β-caryophyllene, α-phellandrene, limonene, β-linalool, 1, 8-cineole, β-pinene, caryophyllene oxide, p-cymene, and eugenol. All of these compounds have been studied extensively regarding their pharmacological properties, such as neuroprotective effect, anti-inflammation, antibacterial, regulation of neurotransmitters and antioxidant effect. Preclinical evidence are reviewed to highlight their diverse mechanisms of action and therapeutic potential to support antidepressant and anxiolytic properties. Additionally, challenges and future directions are also discussed to emphasize therapeutic utility of terpenoids for mental health disorders. Overall, this review provides a promising role of terpenoids as novel therapeutic agents for depression and anxiety, with potential implications for the development of more effective and well-tolerated treatments in the field of psychopharmacology.

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.

The microbiota-gut-brain-immune interface in the pathogenesis of neuroinflammatory diseases: a narrative review of the emerging literature

Importance

Research is beginning to elucidate the sophisticated mechanisms underlying the microbiota-gut-brain-immune interface, moving from primarily animal models to human studies. Findings support the dynamic relationships between the gut microbiota as an ecosystem (microbiome) within an ecosystem (host) and its intersection with the host immune and nervous systems. Adding this to the effects on epigenetic regulation of gene expression further complicates and strengthens the response. At the heart is inflammation, which manifests in a variety of pathologies including neurodegenerative diseases such as Alzheimer's disease, Parkinson's disease, and Multiple Sclerosis (MS).

Observations

Generally, the research to date is limited and has focused on bacteria, likely due to the simplicity and cost-effectiveness of 16s rRNA sequencing, despite its lower resolution and inability to determine functional ability/alterations. However, this omits all other microbiota including fungi, viruses, and phages, which are emerging as key members of the human microbiome. Much of the research has been done in pre-clinical models and/or in small human studies in more developed parts of the world. The relationships observed are promising but cannot be considered reliable or generalizable at this time. Specifically, causal relationships cannot be determined currently. More research has been done in Alzheimer's disease, followed by Parkinson's disease, and then little in MS. The data for MS is encouraging despite this.

Conclusions and relevance

While the research is still nascent, the microbiota-gut-brain-immune interface may be a missing link, which has hampered our progress on understanding, let alone preventing, managing, or putting into remission neurodegenerative diseases. Relationships must first be established in humans, as animal models have been shown to poorly translate to complex human physiology and environments, especially when investigating the human gut microbiome and its relationships where animal models are often overly simplistic. Only then can robust research be conducted in humans and using mechanistic model systems.

Dangers of the chronic stress response in the context of the microbiota-gut-immune-brain axis and mental health: a narrative review

More than 20% of American adults live with a mental disorder, many of whom are treatment resistant or continue to experience symptoms. Other approaches are needed to improve mental health care, including prevention. The role of the microbiome has emerged as a central tenet in mental and physical health and their interconnectedness (well-being). Under normal conditions, a healthy microbiome promotes homeostasis within the host by maintaining intestinal and brain barrier integrity, thereby facilitating host well-being. Owing to the multidirectional crosstalk between the microbiome and neuro-endocrine-immune systems, dysbiosis within the microbiome is a main driver of immune-mediated systemic and neural inflammation that can promote disease progression and is detrimental to well-being broadly and mental health in particular. In predisposed individuals, immune dysregulation can shift to autoimmunity, especially in the presence of physical or psychological triggers. The chronic stress response involves the immune system, which is intimately involved with the gut microbiome, particularly in the process of immune education. This interconnection forms the microbiota-gut-immune-brain axis and promotes mental health or disorders. In this brief review, we aim to highlight the relationships between stress, mental health, and the gut microbiome, along with the ways in which dysbiosis and a dysregulated immune system can shift to an autoimmune response with concomitant neuropsychological consequences in the context of the microbiota-gut-immune-brain axis. Finally, we aim to review evidenced-based prevention strategies and potential therapeutic targets.

Exploring Electrical Neuromodulation as an Alternative Therapeutic Approach in Inflammatory Bowel Diseases

Background and Objectives: This review systematically evaluates the potential of electrical neuromodulation techniques-vagus nerve stimulation (VNS), sacral nerve stimulation (SNS), and tibial nerve stimulation (TNS)-as alternative treatments for inflammatory bowel disease (IBD), including ulcerative colitis (UC) and Crohn's Disease (CD). It aims to synthesize current evidence on the efficacy and safety of these modalities, addressing the significant burden of IBD on patient quality of life and the limitations of existing pharmacological therapies. Materials and Methods: We conducted a comprehensive analysis of studies from PubMed, focusing on research published between 1978 and 2024. The review included animal models and clinical trials investigating the mechanisms, effectiveness, and safety of VNS, SNS, and TNS in IBD management. Special attention was given to the modulation of inflammatory responses and its impact on gastrointestinal motility and functional gastrointestinal disorders associated with IBD. Results: Preliminary findings suggest that VNS, SNS, and TNS can significantly reduce inflammatory markers and improve symptoms in IBD patients. These techniques also show potential in treating related gastrointestinal disorders during IBD remission phases. However, the specific mechanisms underlying these benefits remain to be fully elucidated, and there is considerable variability in treatment parameters. Conclusions: Electrical neuromodulation holds promise as a novel therapeutic avenue for IBD, offering an alternative to patients who do not respond to traditional treatments or experience adverse effects. The review highlights the need for further rigorous studies to optimize stimulation parameters, understand long-term outcomes, and integrate neuromodulation effectively into IBD treatment protocols.

Psychiatric Comorbidities of Inflammatory Bowel Disease: It Is a Matter of Microglia's Gut Feeling

Inflammatory bowel disease (IBD), a common term for Crohn's disease and ulcerative colitis, is a chronic, relapse-remitting condition of the gastrointestinal tract that is increasing worldwide. Psychiatric comorbidities, including depression and anxiety, are more prevalent in IBD patients than in healthy individuals. Evidence suggests that varying levels of neuroinflammation might underlie these states in IBD patients. Within this context, microglia are the crucial non-neural cells in the brain responsible for innate immune responses following inflammatory insults. Alterations in microglia's functions, such as secretory profile, phagocytic activity, and synaptic pruning, might play significant roles in mediating psychiatric manifestations of IBD. In this review, we discuss the role played by microglia in IBD-associated comorbidities.

Gut-brain axis interacts with immunomodulation in inflammatory bowel disease

The brain and the gastrointestinal (GI) tract are important sensory organs in the body and the two-way interaction that exists between them regulates key physiological and homeostatic functions. A growing body of research suggests that this bidirectional communication influences the development and progression of functional GI disorders and plays an important role in the treatment of central nervous system (CNS) disorders. Inflammatory bowel disease (IBD) is a classic intestinal disorder with a high prevalence but still unclear pathogenesis that has been widely discussed in recent years. However, in the studies available to date, we find that many authors have chosen to discuss the influence of the brain on intestinal disorders from the top down, starting with physical and psychological disorders. Coming very naturally, based on these substantial research evidence, we focus on exploring the links between bidirectional communication in the gut-brain axis and IBD, and highlight the role of the gut microbiota, vagus nerve (VN), receptors and immune cells involved in regulating IBD through the gut-brain axis in this review.

Association between inflammatory bowel disease and subsequent depression or anxiety disorders - A retrospective cohort study of 31,728 outpatients

BACKGROUND

Crohn's disease (CD) and ulcerative colitis (UC) are characterized by chronic intestinal and systemic inflammation. The extraintestinal sequelae of inflammatory bowel disease (IBD) are major contributors to disease morbidity and significantly affect patients' quality of life. Here, we evaluated the association between IBD and subsequent depression or anxiety disorder in a large outpatient collective from Germany.

METHODS

15,864 individual IBD patients (CD: n = 6,791, UC: n = 9073) and 15,864 nearest neighbor propensity score matched patients without IBD were included from the Disease Analyzer database (IQVIA). Diagnoses of depression and anxiety disorders were compared between IBD and non-IBD patients during a five-year follow-up period using Kaplan-Meier estimators and Cox-regression models.

RESULTS

After 5 years of follow-up, depression was diagnosed in 14.4% of CD patients versus 10.2% of matched pairs (p < 0.001) and in 13.1% of UC patients versus 10.1% of matched pairs (p < 0.001). In line, the incidence of anxiety order was significantly higher among CD (4.7% vs. 4.4%, p = 0.009) and UC patients (4.3% vs. 3.5%, p = 0.005). Regression analysis confirmed a significant association between IBD and both mental conditions (Hazard Ratio (HR)CD/depression: 1.40, HRUC/depression: 1.32, HRCD/anxiety disorder: 1.21, HRUC/anxiety disorder: 1.28). Subgroup analyses revealed a stronger association for CD and depression (HR: 1.51) and UC and depression (HR:1.49) among male patients as well as UC and anxiety disorders (HR: 1.51) among female patients.

CONCLUSION

Our data argue for a significant association between IBD and mental diseases including depression and anxiety disorders. Although further pathophysiological research is warranted, we hypothesize that specific psychological screening measures in IBD patients could improve quality of life and outcome.

Disruption of the microbiota-gut-brain axis is a defining characteristic of the α-Gal A (-/0) mouse model of Fabry disease

Fabry disease (FD) is an X-linked metabolic disease caused by a deficiency in α-galactosidase A (α-Gal A) activity. This causes accumulation of glycosphingolipids, especially globotriaosylceramide (Gb3), in different cells and organs. Neuropathic pain and gastrointestinal (GI) symptoms, such as abdominal pain, nausea, diarrhea, constipation, and early satiety, are the most frequent symptoms reported by FD patients and severely affect their quality of life. It is generally accepted that Gb3 and lyso-Gb3 are involved in the symptoms; nevertheless, the origin of these symptoms is complex and multifactorial, and the exact mechanisms of pathogenesis are still poorly understood. Here, we used a murine model of FD, the male α-Gal A (-/0) mouse, to characterize functionality, behavior, and microbiota in an attempt to elucidate the microbiota-gut-brain axis at three different ages. We provided evidence of a diarrhea-like phenotype and visceral hypersensitivity in our FD model together with reduced locomotor activity and anxiety-like behavior. We also showed for the first time that symptomology was associated with early compositional and functional dysbiosis of the gut microbiota, paralleled by alterations in fecal short-chain fatty acid levels, which partly persisted with advancing age. Interestingly, most of the dysbiotic features suggested a disruption of gut homeostasis, possibly contributing to accelerated intestinal transit, visceral hypersensitivity, and impaired communication along the gut-brain axis.

Impact of Microbiome-Brain Communication on Neuroinflammation and Neurodegeneration

The gut microbiome plays a pivotal role in maintaining human health, with numerous studies demonstrating that alterations in microbial compositions can significantly affect the development and progression of various immune-mediated diseases affecting both the digestive tract and the central nervous system (CNS). This complex interplay between the microbiota, the gut, and the CNS is referred to as the gut-brain axis. The role of the gut microbiota in the pathogenesis of neurodegenerative diseases has gained increasing attention in recent years, and evidence suggests that gut dysbiosis may contribute to disease development and progression. Clinical studies have shown alterations in the composition of the gut microbiota in multiple sclerosis patients, with a decrease in beneficial bacteria and an increase in pro-inflammatory bacteria. Furthermore, changes within the microbial community have been linked to the pathogenesis of Parkinson's disease and Alzheimer's disease. Microbiota-gut-brain communication can impact neurodegenerative diseases through various mechanisms, including the regulation of immune function, the production of microbial metabolites, as well as modulation of host-derived soluble factors. This review describes the current literature on the gut-brain axis and highlights novel communication systems that allow cross-talk between the gut microbiota and the host that might influence the pathogenesis of neuroinflammation and neurodegeneration.

Key elements determining the intestinal region-specific environment of enteric neurons in type 1 diabetes

Diabetes, as a metabolic disorder, is accompanied with several gastrointestinal (GI) symptoms, like abdominal pain, gastroparesis, diarrhoea or constipation. Serious and complex enteric nervous system damage is confirmed in the background of these diabetic motility complaints. The anatomical length of the GI tract, as well as genetic, developmental, structural and functional differences between its segments contribute to the distinct, intestinal region-specific effects of hyperglycemia. These observations support and highlight the importance of a regional approach in diabetes-related enteric neuropathy. Intestinal large and microvessels are essential for the blood supply of enteric ganglia. Bidirectional morpho-functional linkage exists between enteric neurons and enteroglia, however, there is also a reciprocal communication between enteric neurons and immune cells on which intestinal microbial composition has crucial influence. From this point of view, it is more appropriate to say that enteric neurons partake in multidirectional communication and interact with these key players of the intestinal wall. These interplays may differ from segment to segment, thus, the microenvironment of enteric neurons could be considered strictly regional. The goal of this review is to summarize the main tissue components and molecular factors, such as enteric glia cells, interstitial cells of Cajal, gut vasculature, intestinal epithelium, gut microbiota, immune cells, enteroendocrine cells, pro-oxidants, antioxidant molecules and extracellular matrix, which create and determine a gut region-dependent neuronal environment in diabetes.

The Microbiota-Gut-Brain Axis in Behaviour and Brain Disorders

The gut, along with its microbiota (MB-gut), is the largest absorption organ and reservoir of bacteria in the human body [...].

Rosiglitazone Does Not Affect the Risk of Inflammatory Bowel Disease: A Retrospective Cohort Study in Taiwanese Type 2 Diabetes Patients

Human studies on the effect of rosiglitazone on inflammatory bowel disease (IBD) are still lacking. We investigated whether rosiglitazone might affect IBD risk by using the reimbursement database of Taiwan's National Health Insurance to enroll a propensity-score-matched cohort of ever users and never users of rosiglitazone. The patients should have been newly diagnosed with diabetes mellitus between 1999 and 2006 and should have been alive on 1 January 2007. We then started to follow the patients from 1 January 2007 until 31 December 2011 for a new diagnosis of IBD. Propensity-score-weighted hazard ratios were estimated with regards to rosiglitazone exposure in terms of ever users versus never users and in terms of cumulative duration and cumulative dose of rosiglitazone therapy for dose-response analyses. The joint effects and interactions between rosiglitazone and risk factors of psoriasis/arthropathies, dorsopathies, and chronic obstructive pulmonary disease/tobacco abuse and the use of metformin were estimated by Cox regression after adjustment for all covariates. A total of 6226 ever users and 6226 never users were identified and the respective numbers of incident IBD were 95 and 111. When we compared the risk of IBD in ever users to that of the never users, the estimated hazard ratio (0.870, 95% confidence interval: 0.661-1.144) was not statistically significant. When cumulative duration and cumulative dose of rosiglitazone therapy were categorized by tertiles and hazard ratios were estimated by comparing the tertiles of rosiglitazone exposure to the never users, none of the hazard ratios reached statistical significance. In secondary analyses, rosiglitazone has a null association with Crohn's disease, but a potential benefit on ulcerative colitis (UC) could not be excluded. However, because of the low incidence of UC, we were not able to perform detailed dose-response analyses for UC. In the joint effect analyses, only the subgroup of psoriasis/arthropathies (-)/rosiglitazone (-) showed a significantly lower risk in comparison to the subgroup of psoriasis/arthropathies (+)/rosiglitazone (-). No interactions between rosiglitazone and the major risk factors or metformin use were observed. We concluded that rosiglitazone has a null effect on the risk of IBD, but the potential benefit on UC awaits further investigation.

Association between Inflammatory Bowel Disease and Subsequent Development of Restless Legs Syndrome and Parkinson’s Disease: A Retrospective Cohort Study of 35,988 Primary Care Patients in Germany

Background: In addition to the gastrointestinal symptoms, inflammatory bowel disease (IBD), which includes Crohn’s disease (CD) and ulcerative colitis (UC), is associated with extraintestinal manifestations, including neurological disorders, which are gaining increasing attention due to a recently increased focus on the gut–brain axis. Here we aim to evaluate the association between IBD and restless legs syndrome (RLS) as well as Parkinson’s disease (PD) in a cohort of primary care patients in Germany. Methods: The study included 17,994 individuals with a diagnosis of IBD (7544 with CD and 10,450 with UC) and 17,994 propensity-score-matched individuals without IBD from the Disease Analyzer database (IQVIA). An initial diagnosis of RLS or PD was assessed as a function of IBD. Associations between CD and UC with RLS and PD were analyzed using Cox regression models. Results: During the 10-year observation period, 3.6% of CD patients vs. 1.9% of matched non-IBD pairs (p < 0.001) and 3.2% of UC patients vs. 2.7% of matched pairs (p < 0.001) were diagnosed with RLS. The results were confirmed by Cox regression analysis, which showed a significant association between UC (HR: 1.26; 95% CI: 1.02–1.55) and CD (HR: 1.60; 95% CI: 1.23–2.09) and subsequent RLS. The incidence of PD in IBD patients was not significantly increased. However, we observed a non-significant trend towards a higher incidence of PD in male patients with CD but not UC (HR: 1.55; 95%CI: 0.98–2.45, p = 0.064). Conclusions: The present analysis suggests a significant association between IBD and the subsequent development of RLS. These findings should stimulate further pathophysiological research and may eventually lead to specific screening measures in patients with IBD.