Disturbed autonomic nerve function in patients with Crohn's disease

From gut to brain: understanding the role of microbiota in inflammatory bowel disease

With the proposal of the "biological-psychological-social" model, clinical decision-makers and researchers have paid more attention to the bidirectional interactive effects between psychological factors and diseases. The brain-gut-microbiota axis, as an important pathway for communication between the brain and the gut, plays an important role in the occurrence and development of inflammatory bowel disease. This article reviews the mechanism by which psychological disorders mediate inflammatory bowel disease by affecting the brain-gut-microbiota axis. Research progress on inflammatory bowel disease causing "comorbidities of mind and body" through the microbiota-gut-brain axis is also described. In addition, to meet the needs of individualized treatment, this article describes some nontraditional and easily overlooked treatment strategies that have led to new ideas for "psychosomatic treatment".

Dysfunction of peripheral somatic and autonomic nervous system in patients with severe forms of Crohn's disease on biological therapy with TNFα inhibitors-A single center study

OBJECTIVE

Crohn's disease (CD) can be associated with a wide range of extraintestinal manifestations (EIMs), including neurological ones. Published studies differ in their conclusions about the epidemiology and etiopathogenesis of neurological EIMs. The aims of this study were to demonstrate the presence and find risk factors of peripheral (somatic and autonomic) neuropathy patients with severe CD on anti-TNFα biological therapy.

MATERIAL AND METHODS

A clinical examination focusing on detection of peripheral sensor-motor nervous dysfunction (including Sudoscan) and examination of autonomic nervous system dysfunction (using Ewing´s battery tests and spectral analysis) together with laboratory tests and collection of demographic data followed by administration of questionnaires were performed on a total of 30 neurologically asymptomatic outpatients with severe CD on anti-TNFα biological therapy.

RESULTS

Peripheral sensor-motor nervous function via clinical neurological examination was pathological in 36.7% and Sudoscan in 33.3% of cases. Statistically significant associations between vibration perception test and age, CD and biological therapy duration, body mass index and Crohn's Disease Activity Index were proved while statistically significant associations between temperature perception test and age and BMI were proved as well. Additionally, a decrease of total protein in a patient´s serum below the physiological cut-off in the 6 months prior to measurement was associated with a pathological result of a Sudoscan. Cardiovascular autonomic neuropathy based on Ewing´s battery tests was present in 56.7% of patients, no statistically significant risk factors were found. Our peripheral neuropathy questionnaire correlated with the results of the Sudoscan test and some tests of the clinical examination of peripheral sensor-motor nervous function (discriminatory contact perception test, temperature perception test).

CONCLUSIONS

This study demonstrated a relatively high prevalence of peripheral (especially autonomic) neuropathy and verified some risk factors for the development of peripheral somatic neuropathy in asymptomatic patients with severe form of CD on anti-TNFα biological therapy.

Transcutaneous auricular vagus nerve stimulation attenuates inflammatory bowel disease in children: a proof-of-concept clinical trial

BACKGROUND

Vagus nerve stimulation is an investigational anti-inflammatory therapy targeting the nervous system to modulate immune activity. This study evaluated the efficacy and safety of transcutaneous auricular VNS (ta-VNS) in patients with pediatric-onset Crohn's disease (CD) or ulcerative colitis (UC).

METHODS

Participants were 10-21 years of age with mild/moderate CD or UC and fecal calprotectin (FC) > 200 ug/g within 4 weeks of study entry. Subjects were randomized to receive either ta-VNS targeting the cymba conchae of the external left ear, or sham stimulation, of 5 min duration once daily for a 2-week period, followed by a cross over to the alternative stimulation for an additional 2 weeks. At week 4, all subjects received ta-VNS of 5 min duration twice daily until week 16. Primary study endpoints were clinical remission, and a ≥ 50% reduction in FC level from baseline to week 16. Heart rate variability measurements and patient-reported outcome questionnaires were completed during interval and week 16 assessments.

RESULTS

Twenty-two subjects were enrolled and analyzed (10 CD, 12 UC). Six of 10 with CD had a wPCDAI > 12.5 and 6/12 with UC had a PUCAI > 10 at baseline, correlating to mild to moderate symptom activity. Among the 12 subjects with active symptomatic disease indices at baseline, clinical remission was achieved in 3/6 (50%) with CD and 2/6 (33%) with UC at week 16. Despite all subjects having FC levels ≥ 200 within 4 weeks of enrollment, five subjects (4 UC, 1 CD) had FC levels < 200 at the baseline visit and were excluded from the FC analysis. Of the remaining 17, median baseline FC was 907 µg/g (IQR 411-2,120). At week 16, 11/17 (64.7%) of those with baseline FC ≥ 200 had a ≥ 50% reduction in FC (95% CI 38.3-85.8). In the UC subjects, there was an 81% median reduction in FC vs baseline (833 µg/g; p = 0.03) while in the CD subjects, median reduction in FC at 16 weeks was 51% (357 µg/g; p = 0.09). There were no safety concerns.

CONCLUSION

Noninvasive ta-VNS attenuated signs and symptoms in a pediatric cohort with mild to moderate inflammatory bowel disease.

TRIAL REGISTRATION

NCT03863704-Date of registration 3/4/2019.

Cardiovascular manifestations of inflammatory bowel diseases and the underlying pathogenic mechanisms

Inflammatory bowel disease (IBD), consisting of ulcerative colitis and Crohn's disease, mainly affects the gastrointestinal tract but is also known to have extraintestinal manifestations because of long-standing systemic inflammation. Several national cohort studies have found that IBD is an independent risk factor for the development of cardiovascular disorders. However, the molecular mechanisms by which IBD impairs the cardiovascular system are not fully understood. Although the gut-heart axis is attracting more attention in recent years, our knowledge of the organ-to-organ communication between the gut and the heart remains limited. In patients with IBD, upregulated inflammatory factors, altered microRNAs and lipid profiles, as well as dysbiotic gut microbiota, may induce adverse cardiac remodeling. In addition, patients with IBD have a three- to four times higher risk of developing thrombosis than people without IBD, and it is believed that the increased risk of thrombosis is largely due to increased procoagulant factors, platelet count/activity, and fibrinogen concentration, in addition to decreased anticoagulant factors. The predisposing factors for atherosclerosis are present in IBD and the possible mechanisms may involve oxidative stress system, overexpression of matrix metalloproteinases, and changes in vascular smooth muscle phenotype. This review focuses mainly on 1) the prevalence of cardiovascular diseases associated with IBD, 2) the potential pathogenic mechanisms of cardiovascular diseases in patients with IBD, and 3) adverse effects of IBD drugs on the cardiovascular system. Also, we introduce here a new paradigm for the gut-heart axis that includes exosomal microRNA and the gut microbiota as a cause for cardiac remodeling and fibrosis.

Inflammatory Bowel Disease: Role of Vagus Nerve Stimulation

Vagus nerve stimulation (VNS) is an accepted therapy for the treatment of refractory forms of epilepsy and depression. The brain–gut axis is increasingly being studied as a possible etiological factor of chronic inflammatory diseases, including inflammatory bowel diseases (IBD). A significant percentage of IBD patients lose response to treatments or experience side effects. In this perspective, VNS has shown the first efficacy data. The aim of this narrative review is to underline the biological plausibility of the use of VNS in patients affected by IBD, collect all clinical data in the literature, and hypothesize a target IBD population on which to focus the next clinical study.

Longitudinal Autonomic Nervous System Measures Correlate With Stress and Ulcerative Colitis Disease Activity and Predict Flare

BACKGROUND

Differences in autonomic nervous system function, measured by heart rate variability (HRV), have been observed between patients with inflammatory bowel disease and healthy control patients and have been associated in cross-sectional studies with systemic inflammation. High HRV has been associated with low stress.

METHODS

Patients with ulcerative colitis (UC) were followed for 9 months. Their HRV was measured every 4 weeks using the VitalPatch, and blood was collected at baseline and every 12 weeks assessing cortisol, adrenocorticotropin hormone, interleukin-1β, interleukin-6, tumor necrosis factor-α, and C-reactive protein (CRP). Stool was collected at enrollment and every 6 weeks for fecal calprotectin. Surveys assessing symptoms, stress, resilience, quality of life, anxiety, and depression were longitudinally collected.

RESULTS

Longitudinally evaluated perceived stress was significantly associated with systemic inflammation (CRP, P = 0.03) and UC symptoms (P = 0.02). There was a significant association between HRV and stress (low-frequency to high-frequency power [LFHF], P = 0.04; root mean square of successive differences [RMSSD], P = 0.04). The HRV was associated with UC symptoms (LFHF, P = 0.03), CRP (high frequency, P < 0.001; low frequency, P < 0.001; RMSSD, P < 0.001), and fecal calprotectin (high frequency, P < 0.001; low frequency, P < 0.001; RMSSD, P < 0.001; LFHF, P < 0.001). Significant changes in HRV indices from baseline developed before the identification of a symptomatic or inflammatory flare (P < 0.001).

CONCLUSIONS

Longitudinally evaluated HRV was associated with UC symptoms, inflammation, and perceived and physiological measures of stress. Significant changes in HRV were observed before the development of symptomatic or inflammatory flare.

Bioelectronics in the brain-gut axis: focus on inflammatory bowel disease (IBD)

Accumulating evidence shows that intestinal homeostasis is mediated by cross-talk between the nervous system, enteric neurons and immune cells, together forming specialized neuroimmune units at distinct anatomical locations within the gut. In this review, we will particularly discuss how the intrinsic and extrinsic neuronal circuitry regulates macrophage function and phenotype in the gut during homeostasis and aberrant inflammation, such as observed in inflammatory bowel disease (IBD). Furthermore, we will provide an overview of basic and translational IBD research using these neuronal circuits as a novel therapeutic tool. Finally, we will highlight the different challenges ahead to make bioelectronic neuromodulation a standard treatment for intestinal immune-mediated diseases.

A Review of Inflammatory Bowel Disease: A Model of Microbial, Immune and Neuropsychological Integration

Objective: Inflammatory bowel diseases (IBDs) are complex chronic inflammatory disorders of the gastro-intestinal (GI) tract with uncertain etiology. IBDs comprise two idiopathic disorders: Crohn's disease (CD) and ulcerative colitis (UC). The aetiology, severity and progression of such disorders are still poorly understood but thought to be influenced by multiple factors (including genetic, environmental, immunological, physiological, psychological factors and gut microbiome) and their interactions. The overarching aim of this review is to evaluate the extent and nature of the interrelationship between these factors with the disease course. A broader conceptual and longitudinal framework of possible neuro-visceral integration, core microbiome analysis and immune modulation assessment may be useful in accurately documenting and characterizing the nature and temporal continuity of crosstalk between these factors and the role of their interaction (s) in IBD disease activity. Characterization of these interactions holds the promise of identifying novel diagnostic, interventions, and therapeutic strategies. Material and Methods: A search of published literature was conducted by exploring PubMed, EMBASE, MEDLINE, Medline Plus, CDSR library databases. Following search terms relating to key question were set for the search included: "Inflammatory bowel diseases," "gut microbiota," "psychological distress and IBD," "autonomic reactivity and IBD," "immune modulation," "chronic inflammation," "gut inflammation," "enteric nervous system," "gut nervous system," "Crohn's disease," "Ulcerative colitis", "depression and IBD", "anxiety and IBD", "quality of life in IBD patients," "relapse in IBDs," "remission in IBDs," "IBD disease activity," "brain-gut-axis," "microbial signature in IBD," "validated questionnaires in IBD," "IBD activity indices," "IBD aetiology," "IBDs and stress," "epidemiology of IBDs", "autonomic nervous system and gut inflammation", "IBD and environment," "genetics of IBDs," "pathways of immune response in IBDs," "sleep disturbances in IBD," "hypothalamic-pituitary-adrenal axis (HPA)," "sympatho-adrenal axis," "CNS and its control of gut function" "mucosal immune response," "commensal and pathogenic bacteria in the gut," "innate and adaptive immunity." Studies evaluating any possible associations between gut microbiome, psychological state, immune modulation, and autonomic function with IBDs were identified. Commonly cited published literatures with high quality research methodology/results and additional articles from bibliographies of recovered papers were examined and included where relevant. Results: Although there is a substantial literature identifying major contributing factors with IBD, there has been little attempt to integrate some factors over time and assess their interplay and relationship with IBD disease activity. Such contributing factors include genetic and environmental factors, gut microbiota composition and function, physiological factors, psychological state and gut immune response. Interdependences are evident across psychological and biological factors and IBD disease activity. Although from the available evidence, it is implausible that a single explanatory model could elucidate the interplay between such factors and the disease course as well as the sequence of the effect during the pathophysiology of IBD. Conclusion: Longitudinal monitoring of IBD patients and integrating data related to the contributing/risk factors including psychological state, physiological conditions, inflammatory/immune modulations, and microbiome composition/function, could help to explain how major factors associate and interrelate leading to exacerbation of symptoms and disease activity. Identifying the temporal trajectory of biological and psychosocial disturbances may also help to assess their effects and interdependence on individuals' disease status. Moreover, this allows greater insight into understanding the temporal progressions of subclinical events as potential ground for disease severity in IBD. Furthermore, understanding the interaction between these risk factors may help better interventions in controlling the disease, reducing the costs related to disease management, further implications for clinical practice and research approaches in addition to improving patients' mental health and quality of life.

Therapeutic Potential of Vagus Nerve Stimulation for Inflammatory Bowel Diseases

The vagus nerve is a mixed nerve, comprising 80% afferent fibers and 20% efferent fibers. It allows a bidirectional communication between the central nervous system and the digestive tract. It has a dual anti-inflammatory properties via activation of the hypothalamic pituitary adrenal axis, by its afferents, but also through a vago-vagal inflammatory reflex involving an afferent (vagal) and an efferent (vagal) arm, called the cholinergic anti-inflammatory pathway. Indeed, the release of acetylcholine at the end of its efferent fibers is able to inhibit the release of tumor necrosis factor (TNF) alpha by macrophages via an interneuron of the enteric nervous system synapsing between the efferent vagal endings and the macrophages and releasing acetylcholine. The vagus nerve also synapses with the splenic sympathetic nerve to inhibit the release of TNF-alpha by splenic macrophages. It can also activate the spinal sympathetic system after central integration of its afferents. This anti-TNF-alpha effect of the vagus nerve can be used in the treatment of chronic inflammatory bowel diseases, represented by Crohn’s disease and ulcerative colitis where this cytokine plays a key role. Bioelectronic medicine, via vagus nerve stimulation, may have an interest in this non-drug therapeutic approach as an alternative to conventional anti-TNF-alpha drugs, which are not devoid of side effects feared by patients.

Neuronal innervation of the intestinal crypt

Mucosal damage is a key feature of inflammatory bowel diseases (IBD) and healing of the mucosa is an endpoint of IBD treatment that is often difficult to achieve. Autonomic neurons of the parasympathetic and sympathetic nervous system may influence intestinal epithelial cell growth and modulating epithelial innervation could for that reason serve as an interesting therapeutic option to improve mucosal healing. Understanding of the biological processes triggered by nonspecific and specific epithelial adrenergic and cholinergic receptor activation is of key importance. At present, with rising technological advances, bioelectronic neuromodulation as treatment modality has gained momentum. We discuss the current view on state-of-the-art innervation of the intestinal crypt and its impact on epithelial cell growth and differentiation. Furthermore, we outline bioelectronic technology and review its relevance to wound healing processes.

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.

Potential of Electrical Neuromodulation for Inflammatory Bowel Disease

Inflammatory bowel disease (IBD) is a common chronic inflammatory disease of the digestive tract that is often debilitating. It affects patients' quality of life and imposes a financial burden. Despite advances in treatment with medications such as biologics, a large proportion of patients do not respond to medical therapy or develop adverse events. Therefore, alternative treatment options such as electrical neuromodulation are currently being investigated. Electrical neuromodulation, also called bioelectronic medicine, is emerging as a potential new treatment for IBD. Over the past decade, advancements have been made in electrical neuromodulation. A number of electrical neuromodulation methods, such as vagus nerve stimulation, sacral nerve stimulation, and tibial nerve stimulation, have been tested to treat IBD. A series of animal and clinical trials have been performed to evaluate efficacy with promising results. Although the exact underlying mechanisms of action for electrical neuromodulation remain to be explored, this modality is promising. Further randomized controlled trials and basic experiments are needed to investigate efficacy and clarify intrinsic mechanisms.

Neuropathy and primary headaches affect different subgroups of inflammatory bowel disease patients

BACKGROUND

Peripheral neuropathies (PN) and primary headaches (PH) are common comorbidities in inflammatory bowel disease (IBD) patients. We aimed to evaluate whether PN and PH affect the same subgroups of IBD patients.

METHODS

Since 2004, we established a cohort study to evaluate neurological diseases in IBD patients. Over 2 years, all consecutive (N = 155) IBD patients (either Crohn's disease (CD) or ulcerative colitis (UC) were evaluated for the presence of PN and PH. PH were also evaluated in dyspeptic patients (N = 84) and IBD relatives (controls, N = 101). After neurological evaluation, symptomatic patients underwent skin wrinkling test to evaluate small fiber function and/or electromyography.

RESULTS

Headaches and migraine were more prevalent in IBD than control patients: 52.3 and 34.2% vs. 40.6 and 20.8% (P < 0.05). Migraine was 2.6 times more common in CD patients than controls (CI = 1.34-5.129) and 8.6 times (13.3 times in the CD group) more common in men with IBD (P < 0.05). Headache and migraine were also more common in dyspeptic patients (P < 0.05). Chi-square, univariate, and multivariate regression analysis did not disclose any association between PN, headache, or PH (P > 0.05). Multivariate regression analysis disclosed that headaches were more prevalent in women, co-existing psychiatric disease, IBD, CD, and UC. After age, gender distribution, and prevalence of hypertension and psychiatric diseases were matched among the groups, there were still differences in the prevalence of headaches and migraine among IBD, CD, and UC versus control patients.

CONCLUSION

In summary, PH and PN are common in IBD and do not affect the same subgroups of patients.

A novel method of sacral nerve stimulation for colonic inflammation

BACKGROUND

Vagal nerve stimulation has been reported to treat inflammation with promising results. The aims of our study were to optimize sacral nerve stimulation (SNS) methodologies for colonic inflammation in a rodent model of colitis and to investigate autonomic and cytokine mechanisms.

METHODS

Three major efforts were made in optimizing SNS: (a) to determine the best stimulation duration: SNS-0.5h daily, SNS-1h daily, and SNS-3h daily with the parameters set at 5 Hz, 10 seconds on, 90 seconds off; (b) to determine the best stimulation position: bilateral, bipolar, and unipolar stimulation; (c) to determine the best stimulation parameters: our 5 Hz intermittent stimulation vs 14 Hz-210 μs continuous stimulation. Inflammatory responses were assessed by the disease activity index (DAI), histological analyses, and the myeloperoxidase (MPO) activity. Levels of inflammatory cytokines, norepinephrine (NE), and pancreatic polypeptide (PP) in both plasma and colon tissues were assessed.

KEY RESULTS

Both SNS-1h and SNS-3h significantly ameliorated intestinal inflammation; SNS-1h was superior to SNS-3h. Bipolar but not bilateral or unipolar stimulation improved the inflammation in colitis. SNS with 5 Hz intermittent stimulation but not the 14 Hz continuous SNS was better for treating colitis in rats. SNS with the optimized stimulation parameters increased vagal activity and decreased sympathetic activity. CONCLUSION & INFERENCES: Bipolar stimulation for 1 hour daily using intermittent 5 Hz parameters is most effective in improving colonic inflammation in TNBS-treated rats by inhibiting pro-inflammatory cytokines and increasing anti-inflammatory cytokines via the modulation of the autonomic function.

Sacral nerve stimulation improves colonic inflammation mediated by autonomic-inflammatory cytokine mechanism in rats

BACKGROUND

Vagal nerve stimulation (VNS) was reported to have a therapeutic potential for inflammatory bowel disease (IBD). This study was designed to determine effects and mechanisms of SNS on colonic inflammation of in rodent models of IBD and compare the difference among SNS, VNS, and SNS plus VNS.

METHODS

Intestinal inflammation in rats was induced by intrarectal administration of TNBS (2,4,6-Trinitrobenzenesulfonic acid) on the first day. Five days after intrarectal TNBS, the rats were treated with sham-VNS, VNS, Sham-SNS, SNS, and SNS + VNS for 10 days. In another experiment, after 10 days of 4% DSS (dextran sodium sulfate) in drinking water, rats were treated with 10-day sham-SNS and SNS. Various inflammatory responses were assessed; mechanisms involving autonomic functions and inflammatory cytokines were investigated.

KEY RESULTS

(a) VNS, SNS, and VNS + SNS significantly and equally decreased the disease activity index and macroscopic scores, and normalized colon length; (b) IL-10 was decreased by TNBS but increased with SNS, VNS, and SNS + VNS; pro-inflammatory cytokines, IL-6, IL-17A, MCP-1 and TNF-α, were increased by TNBS but decreased with SNS, VNS, and SNS + VNS (P < .05); MPO activity was decreased by SNS, VNS, and SNS + VNS; (c) SNS, VNS, and SNS + VNS remarkably increased vagal activity that was suppressed by TNBS (P < .05); (d) smilar SNS effects were noted in rats with DSS-induced colitis.

CONCLUSIONS & INFERENCES

SNS presents similar anti-inflammatory effects as VNS by inhibiting pro-inflammatory cytokines and increasing anti-inflammatory cytokines via the autonomic pathway. Similar to VNS, SNS may also have a therapeutic potential for colonic inflammation.

Review article: the role of the autonomic nervous system in the pathogenesis and therapy of IBD

BACKGROUND

There is a growing body of evidence implicating a role for the brain-gut axis in the pathogenesis of inflammation in patients with IBD.

AIMS

To perform a narrative review of published literature regarding the association of the autonomic nervous system and intestinal inflammation and to describe the rationale for and emerging use of autonomic manipulation as a therapeutic agent METHODS: Current relevant literature was summarised and critically examined.

RESULTS

There is substantial pre-clinical and clinical evidence for a multifaceted anti-inflammatory effect of the vagus at both systemic and local intestinal levels. It acts via acetylcholine-mediated activation of α-7-acetylcholine receptors involving multiple cell types in innate and adaptive immunity and the enteric nervous system with subsequent protective influences on the intestinal barrier, inflammatory mechanisms and the microbiome. In patients with IBD, there is evidence for a sympatho-vagal imbalance, functional enteric neuronal depletion and hyporeactivity of the hypothalamic-pituitary-adrenal axis. Direct or transcutaneous vagal neuromodulation up-regulates the cholinergic anti-inflammatory pathway in pre-clinical and clinical models with down-regulation of systemic and local intestinal inflammation. This is supported by two small studies in Crohn's disease although remains to be investigated in ulcerative colitis.

CONCLUSIONS

Modulating the cholinergic anti-inflammatory pathway influences inflammation both systemically and at a local intestinal level. It represents a potentially underutilised anti-inflammatory therapeutic strategy. Given the likely pathogenic role of the autonomic nervous system in patients with IBD, vagal neuromodulation, an apparently safe and successful means of increasing vagal tone, warrants further clinical exploration.

Impaired Autonomic Nervous System-Microbiome Circuit in Hypertension

Hypertension affects an estimated 103 million Americans, yet gaps in knowledge continue to limit its successful management. Rapidly emerging evidence is linking gut dysbiosis to many disorders and diseases including hypertension. The evolution of the -omics techniques has allowed determination of the abundance and potential function of gut bacterial species by next-generation bacterial sequencing, whereas metabolomics techniques report shifts in bacterial metabolites in the systemic circulation of hypertensive patients and rodent models of hypertension. The gut microbiome and host have evolved to exist in balance and cooperation, and there is extensive crosstalk between the 2 to maintain this balance, including during regulation of blood pressure. However, an understanding of the mechanisms of dysfunctional host-microbiome interactions in hypertension is still lacking. Here, we synthesize some of our recent data with published reports and present concepts and a rationale for our emerging hypothesis of a dysfunctional gut-brain axis in hypertension. Hopefully, this new information will improve the understanding of hypertension and help to address some of these knowledge gaps.

Intestinal macrophages and their interaction with the enteric nervous system in health and inflammatory bowel disease

Over the past decades, there has been an increasing understanding of cellular and molecular mechanisms that mediate modulation of the immune system by the autonomic nervous system. The discovery that vagal nerve stimulation (VNS) attenuates endotoxin-induced experimental sepsis paved the way for further studies investigating neuro-immune interaction. In particular, great attention is now given to intestinal macrophages: several studies report the existence of both intrinsic and extrinsic neural mechanisms by which intestinal immune homoeostasis can be regulated in different layers of the intestine, mainly by affecting macrophage activation through neurotransmitter release. Given the important role of inflammation in numerous disease processes, such as inflammatory bowel disease (IBD), cholinergic anti-inflammatory mechanisms are under intense investigation both from a basic and clinical science perspective in immune-mediated diseases such as IBD. This review discusses recent insights on the cross-talk between enteric neurons and the immune system, especially focusing on macrophages, and provides an overview of basic and translational aspects of the cholinergic anti-inflammatory response as therapeutic alternative to reinstall immune homoeostasis in intestinal chronic inflammation.

Chronic Sinonasal Disease in Patients with Inflammatory Bowel Disease

Background

The objective of this study was to explore the possible relationship between inflammatory bowel disease (IBD) and chronic sinonasal disease.

Methods

A cross-sectional study was undertaken of 241 patients with Crohn's disease (CD) or ulcerative colitis from a tertiary medical center IBD clinic. Patient demographic data and information regarding IBD diagnosis and management, sinonasal disease diagnosis and management, and complications related to these diagnoses were gathered by retrospective chart review and a standardized patient survey.

Results

One hundred sixty surveys (67%) were returned and analyzed. Overall, 48% of patients with IBD reported chronic sinonasal disease symptoms. Patients with CD had a higher prevalence of sinonasal disease than patients with ulcerative colitis (53% versus 32%; p < 0.02). The subgroup of CD patients with obstructive bowel complications had the highest prevalence of sinonasal disease (68% versus 27%; p = < 0.001), with 23% reporting chronic rhinosinusitis, 13% reporting chronic rhinitis, and an additional 32% reporting chronic nasal or sinus symptoms.

Conclusion

The prevalence of chronic sinonasal disease is elevated in patients with IBD, occurring in approximately one-half of patients followed at a tertiary IBD center. Patients with CD experiencing obstructive complications had significantly increased rates of sinonasal disease. The relationship between chronic sinonasal disease and obstructive CD is not defined, but several hypotheses are generated.

Neuromodulation in Inflammatory Skin Disease

Inflammatory skin diseases are difficult to treat because of a lack of available treatment options for severe disease. However, recent advances have shown that vagus nerve stimulation can be used to decrease inflammation and reduce disease severity in rheumatoid arthritis and inflammatory bowel disease. Changes in cytokine profiles observed in these studies are similar to those seen with use of biologics in inflammatory skin disease, suggesting that they act along similar pathways to disrupt chronic inflammation and treat inflammatory disease. This commentary explores the existing evidence demonstrating the efficacy of neuromodulation in inflammatory disease, and outlines reasons why these findings could translate to the dermatology setting to treat inflammatory skin disease.

The role of alpha7 nicotinic acetylcholine receptors in inflammatory bowel disease: involvement of different cellular pathways

INTRODUCTION

Autonomic imbalance plays a pivotal role in the pathophysiology of inflammatory bowel diseases (IBD). The central nervous system (CNS) cooperates dynamically with the immune system to regulate inflammation through humoral and neural pathways. In particular, acetylcholine (Ach), the main neurotransmitter in the vagus nerve, decreases the production of pro-inflammatory cytokines through a mechanism dependent on the α7 nicotinic Ach receptors (α7nAChRs). Areas covered: Here, we review the evidence for involvement of the cholinergic anti-inflammatory pathway (CAP) in IBD. We also elaborate the role of α7nAChRs and subsequent cellular pathways in CAP. Finally, we review potential therapeutic implications of modulators of these receptors. Expert opinion: Alpha7nAChR modulators possess both cognitive improving and anti-inflammatory properties. Although, these agents demonstrated therapeutic benefits in experimental models, their efficacy has not always been translated in clinical trials. Thus, development of more specific α7nAChR ligands as well as more experimental studies and better controlled trials, especially in the field of IBD, are encouraged for a progress in this field.

The Vagus Nerve in the Neuro-Immune Axis: Implications in the Pathology of the Gastrointestinal Tract

The vagus nerve (VN) is the longest nerve of the organism and a major component of the parasympathetic nervous system which constitutes the autonomic nervous system (ANS), with the sympathetic nervous system. There is classically an equilibrium between the sympathetic and parasympathetic nervous systems which is responsible for the maintenance of homeostasis. An imbalance of the ANS is observed in various pathologic conditions. The VN, a mixed nerve with 4/5 afferent and 1/5 efferent fibers, is a key component of the neuro-immune and brain-gut axes through a bidirectional communication between the brain and the gastrointestinal (GI) tract. A dual anti-inflammatory role of the VN is observed using either vagal afferents, targeting the hypothalamic–pituitary–adrenal axis, or vagal efferents, targeting the cholinergic anti-inflammatory pathway. The sympathetic nervous system and the VN act in synergy, through the splenic nerve, to inhibit the release of tumor necrosis factor-alpha (TNFα) by macrophages of the peripheral tissues and the spleen. Because of its anti-inflammatory effect, the VN is a therapeutic target in the treatment of chronic inflammatory disorders where TNFα is a key component. In this review, we will focus on the anti-inflammatory role of the VN in inflammatory bowel diseases (IBD). The anti-inflammatory properties of the VN could be targeted pharmacologically, with enteral nutrition, by VN stimulation (VNS), with complementary medicines or by physical exercise. VNS is one of the alternative treatments for drug resistant epilepsy and depression and one might think that VNS could be used as a non-drug therapy to treat inflammatory disorders of the GI tract, such as IBD, irritable bowel syndrome, and postoperative ileus, which are all characterized by a blunted autonomic balance with a decreased vagal tone.

Vagus nerve stimulation: a new promising therapeutic tool in inflammatory bowel disease

Inflammatory bowel disease (IBD), that is Crohn's disease (CD) and ulcerative colitis, affects about 1.5 million persons in the USA and 2.2 million in Europe. The pathophysiology of IBD involves immunological, genetic and environmental factors. The treatment is medico-surgical but suspensive. Anti-TNFα agents have revolutionized the treatment of IBD but have side effects. In addition, a non-negligible percentage of patients with IBD stop or take episodically their treatment. Consequently, a nondrug therapy targeting TNFα through a physiological pathway, devoid of major side effects and with a good cost-effectiveness ratio, would be of interest. The vagus nerve has dual anti-inflammatory properties through its afferent (i.e. hypothalamic-pituitary-adrenal axis) and efferent (i.e. the anti-TNFα effect of the cholinergic anti-inflammatory pathway) fibres. We have shown that there is an inverse relationship between vagal tone and plasma TNFα level in patients with CD, and have reported, for the first time, that chronic vagus nerve stimulation has anti-inflammatory properties in a rat model of colitis and in a pilot study performed in seven patients with moderate CD. Two of these patients failed to improve after 3 months of vagus nerve stimulation but five were in deep remission (clinical, biological and endoscopic) at 6 months of follow-up and vagal tone was restored. No major side effects were observed. Thus, vagus nerve stimulation provides a new therapeutic option in the treatment of CD.

Gastric emptying and disease activity in inflammatory bowel disease

BACKGROUND

Gastric emptying (GE) is delayed in a subset of patients with inflammatory bowel disease (IBD). We have shown before that altered release of gastrointestinal hormones may contribute to GE disturbances, but overall effects of disease activity remain unclear. Thus, we aimed to evaluate GE in patients with IBD during active disease and following therapy.

DESIGN

A total of 20 healthy subjects (HC) and 26 patients with IBD hospitalized because of an acute episode of their disease (Crohn's disease (CD) n = 13, ulcerative colitis (UC) n = 13) underwent a standardized (13) C-octanoic acid GE breath test (baseline test). Plasma glucose, cholecystokinin (CCK), peptide YY (PYY) and glucagon-like peptide-1 (GLP-1) were measured periodically throughout the test. A total of 16 patients underwent a second GE test after 3-4 months of therapy.

RESULTS

At baseline, nine patients with IBD had pathologically delayed GE half-time (T½ > 150 min) (P = 0·028 vs. HC). Moreover, T½ was significantly longer in the total group of patients with IBD than in HC (129 ± 12 min vs. 96 ± 7, P = 0·030). Postprandial GLP-1 responses were elevated in IBD (P = 0·002 vs. HC) and correlated with T½ (P = 0·05). Following therapy clinical activity indices and T½ were decreased in IBD (P ≤ 0·01 vs. baseline), and T½ no longer differed from HC (P > 0·5). Moreover, GLP-1 plasma levels decreased significantly (P = 0·031).

CONCLUSIONS

Higher disease activity in IBD is associated with prolonged GE and increased release of GLP-1. Following effective therapy, GE is accelerated and GLP-1 release decreases significantly. Thus, increased release of GLP-1 from the inflamed mucosa might contribute to GE disturbances in IBD.

Autonomic Dysfunction Correlates with Clinical and Inflammatory Activity in Patients with Crohn's Disease

BACKGROUND

Autonomic dysfunction has been implicated in Crohn's disease (CD). We aimed to investigate heart rate variability (HRV) as a marker of possible autonomic imbalance in patients with CD.

METHODS

Thirty patients with CD and 30 age- and gender-matched healthy controls were enrolled in a prospective cohort study and underwent HRV study. Anxiety level was scored using the STAI questionnaire and CD clinical activity was assessed by Harvey-Bradshaw index. Blood tests including inflammatory markers were obtained for all participants.

RESULTS

CD subjects had lower mean blood pressure (85.51 ± 11.07 mm Hg, 91.51 ± 6.99, P = 0.015) and albumin and significantly higher CRP and IL-6 compared with controls (P < 0.002 for all comparisons). Mean HRV values of very low-frequency power and low-frequency power components were significantly lower among CD subjects (P = 0.038 and 0.027, respectively), implying a predominant sympathetic tone. Anxiety level scores were significantly higher among patients with CD for both state anxiety (P = 0.001) and trait anxiety (P < 0.0001). However, patients with active disease had similar anxiety scores as patients in remission, yet had a significantly lower BMI, lower albumin level, and higher CRP and IL-6 levels (P < 0.05 for all comparisons). Moreover, despite similar anxiety scores, patients with active disease had higher pulse rate (P = 0.02) and lower HRV indexes, which correlated with albumin levels(r = 0.7, P = 0.001).

CONCLUSIONS

Although patients with CD have higher anxiety levels compared with controls, they exhibit depressed HRV independent of this anxiety state and in direct correlation with disease activity and inflammatory markers. These observations suggest an inherent imbalance of autonomic function associated with active inflammation.

Peripheral neuropathy: an underreported neurologic manifestation of inflammatory bowel disease

BACKGROUND AND AIMS

One of the most frequent neurologic complications reported in inflammatory bowel disease population is peripheral neuropathy; however, clinical aspects of peripheral nerve damage are not well characterized. The aim of the review is to present the existing literature on peripheral neuropathy in inflammatory bowel disease patients.

METHODS

A literature search identified the publications reporting on epidemiology, clinical features, underlying mechanisms and management of ulcerative colitis and Crohn's disease patients with peripheral nerve involvement.

RESULTS

The pathogenesis of peripheral nervous system damage in inflammatory bowel disease has yet to be elucidated, although it seems to be related to immune mechanisms; therefore, treatment with immunotherapy is recommended. In addition, peripheral neuropathy may appear as iatrogenic-related disorders associated with several drugs used in controlling inflammatory bowel disease activity; finally, peripheral neuropathy may also be caused by micronutrient deficiencies secondary to malabsorption-related disorders.

CONCLUSIONS

Although peripheral nervous nerve damage associated with inflammatory bowel disease is rarely reported, clinicians should be aware of the peripheral neuropathy clinical manifestations in order to recognize it and provide early treatment, which is crucial for preventing major neurologic morbidity. Heightened awareness is necessary for the successful management of these patients.

Alterations in the distal colon innervation in Winnie mouse model of spontaneous chronic colitis

The gastrointestinal tract is innervated by extrinsic sympathetic, parasympathetic and sensory nerve fibers as well as by intrinsic fibers from the neurons in myenteric and submucosal ganglia embedded into the gastrointestinal wall. Morphological and functional studies of intestinal innervation in animal models are important for understanding the pathophysiology of inflammatory bowel disease (IBD). The recently established Winnie mouse model of spontaneous chronic colitis caused by a point mutation in the Muc2 mucin gene develops inflammation due to a primary epithelial defect. Winnie mice display symptoms of diarrhea, ulcerations and rectal bleeding similar to those in IBD. In this study, we investigated myenteric neurons, noradrenergic, cholinergic and sensory nerve fibers in the distal colon of Winnie (Win/Win) mice compared to C57/BL6 and heterozygote littermates (Win/Wt) using histological and immunohistochemical methods. All Win/Win mice used in this study had inflammation with signs of mucosal damage, goblet cell loss, thickening of muscle and mucosal layers, and increased CD45-immunoreactivity in the distal colon. The density of sensory, cholinergic and noradrenergic fibers innervating the myenteric plexus, muscle and mucosa significantly decreased in the distal colon of Win/Win mice compared to C57/BL6 and Win/Wt mice, while the total number of myenteric neurons as well as subpopulations of cholinergic and nitrergic neurons remained unchanged. In conclusion, changes in the colon morphology and innervation found in Winnie mice have multiple similarities with changes observed in patients with ulcerative colitis.

Autonomic effects of music in health and Crohn's disease: the impact of isochronicity, emotional valence, and tempo

BACKGROUND

Music can evoke strong emotions and thus elicit significant autonomic nervous system (ANS) responses. However, previous studies investigating music-evoked ANS effects produced inconsistent results. In particular, it is not clear (a) whether simply a musical tactus (without common emotional components of music) is sufficient to elicit ANS effects; (b) whether changes in the tempo of a musical piece contribute to the ANS effects; (c) whether emotional valence of music influences ANS effects; and (d) whether music-elicited ANS effects are comparable in healthy subjects and patients with Crohn´s disease (CD, an inflammatory bowel disease suspected to be associated with autonomic dysfunction).

METHODS

To address these issues, three experiments were conducted, with a total of n = 138 healthy subjects and n = 19 CD patients. Heart rate (HR), heart rate variability (HRV), and electrodermal activity (EDA) were recorded while participants listened to joyful pleasant music, isochronous tones, and unpleasant control stimuli.

RESULTS

Compared to silence, both pleasant music and unpleasant control stimuli elicited an increase in HR and a decrease in a variety of HRV parameters. Surprisingly, similar ANS effects were elicited by isochronous tones (i.e., simply by a tactus). ANS effects did not differ between pleasant and unpleasant stimuli, and different tempi of the music did not entrain ANS activity. Finally, music-evoked ANS effects did not differ between healthy individuals and CD patients.

CONCLUSIONS

The isochronous pulse of music (i.e., the tactus) is a major factor of music-evoked ANS effects. These ANS effects are characterized by increased sympathetic activity. The emotional valence of a musical piece contributes surprisingly little to the ANS activity changes evoked by that piece.

Lost among the trees? The autonomic nervous system and paediatrics

The autonomic nervous system (ANS) has been strikingly neglected in Western medicine. Despite its profound importance for regulation, adjustment and coordination of body systems, it lacks priority in training and practice and receives scant attention in numerous major textbooks. The ANS is integral to manifestations of illness, underlying familiar physical and psychological symptoms. When ANS activity is itself dysfunctional, usual indicators of acute illness may prove deceptive. Recognising the relevance of the ANS can involve seeing the familiar through fresh eyes, challenging assumptions in clinical assessment and in approaches to practice. Its importance extends from physical and psychological well-being to parenting and safeguarding, public services and the functioning of society. Exploration of its role in conditions ranging from neurological, gastrointestinal and connective tissue disorders, diabetes and chronic fatigue syndrome, to autism, behavioural and mental health difficulties may open therapeutic avenues. The ANS offers a mechanism for so-called functional illnesses and illustrates the importance of recognising that 'stress' takes many forms, physical, psychological and environmental, desirable and otherwise. Evidence of intrauterine and post-natal programming of ANS reactivity suggests that neonatal care and safeguarding practice may offer preventive opportunity, as may greater understanding of epigenetic change of ANS activity through, for example, accidental or psychological trauma or infection. The aim of this article is to accelerate recognition of the importance of the ANS throughout paediatrics, and of the potential physical and psychological cost of neglecting it.

Brain-gut interactions and inflammatory bowel disease: Implications for acupuncture and moxibustion treatment

Inflammatory bowel disease is a chronic recurrent intestinal inflammatory disorder. The role of dysfunction of brain-gut interactions in the pathogenesis of IBD has recently been intensively investigated. Numerous studies have shown that the central nervous system, the hypothalamus - pituitary - adrenal axis (HPA axis), the hypothalamus - the autonomic nervous system axis (HANS axis), and intestinal response functions develop varying degrees of dysfunction in IBD patients and are closely related to disease activity. It has been proven that acupuncture and moxibustion therapy is an effective means for the treatment of IBD, and the holistic regulation of the function of brain-gut interactions may be the key effect mechanism of acupuncture and moxibustion treatment in IBD. In this paper, we aim to explain the mechanism of brain-gut interactions in IBD as well as traditional Chinese medicine theory on brain-gut interactions, and on this basis, we explore the possible mechanism of acupuncture and moxibution treatment.

Neurologic complications in patients with inflammatory bowel disease: increasing relevance in the era of biologics

Extraintestinal manifestations of inflammatory bowel disease (IBD) can involve almost every organ system. Neurologic complications are not infrequent in patients with IBD, but are poorly recognized and underreported. Pathophysiologically, these may represent immune-mediated phenomenon, nonimmunologic complications due to micronutrient deficiencies, thromboembolism, or be medication-induced. Peripheral neuropathy is the most common neurologic complication of IBD and may be immune-mediated, or caused by therapy with anti-tumor necrosis factor-alpha (TNF-α) therapy or metronidazole. Multiple sclerosis occurs with a greater frequency in patients with IBD. Anti-TNF-α therapy can cause neurologic disease characterized by central demyelination that mimics multiple sclerosis. Hence, patients with a history of demyelinating diseases or with symptoms of polyneuropathy should be carefully evaluated before initiation of anti-TNF-α therapy. Natalizumab has been associated with fatal progressive multifocal leukoencephalopathy due to reactivation of JC virus, and occurs with greater frequency in patients with previous JC virus infection. Stroke secondary to venous or arterial thromboembolism can be seen in patients with active Crohn's disease. It is important for gastroenterologists to be aware of the neurologic complications in patients with IBD. Neurologic symptoms in these patients should be promptly evaluated.

Decreased neuromuscular function in Crohn's disease patients is not associated with low serum vitamin D levels

BACKGROUND

Neuromuscular fatigue is a common complaint in Crohn's disease (CD) patients. A correlation between serum vitamin D concentrations and neuromuscular function has been found in the elderly or non-ambulant populations.

AIMS

The aim of this study was to determine whether CD patients exhibit impaired neuromuscular function and if so, is there a link between vitamin D and neuromuscular function.

METHODS

Crohn's disease patients (n = 19) with at least one prior small bowel resection and matched controls (n = 19) underwent muscle strength and endurance testing, vitamin D, and nerve function analysis.

RESULTS

Knee extension and flexion peak torque (Nm/kg) were greater in the control group than in the CD patients (P = 0.04 and 0.014, respectively. A significant difference was found between fatigue rates of the rectus femoris (P = 0.015) between CD patients and controls, but no difference was found in serum vitamin D levels between groups (P = 0.317). Knee extension and flexion torque measurements, with age as a covariate, were compared with high and low vitamin D levels. Those subjects with high serum vitamin D levels had a significantly greater extension peak torque (P = 0.045) and extension average torque (Nm/kg) (P = 0.014) than those with low levels.

CONCLUSION

Crohn's disease patients with sufficient vitamin D levels experienced a 43 % greater extension peak torque. Although vitamin D deficiency has been associated with neuromuscular dysfunction, there were no differences in serum vitamin D levels between the CD and healthy controls to explain the decreased muscle strength.

Impaired gastric emptying in primary Sjogren's syndrome

OBJECTIVE

To investigate the prevalence of impaired gastric emptying (IGE) and its relation to autonomic nervous dysfunction (AD), functional bowel syndrome, and inflammatory and serological variables in patients with primary Sjögren's syndrome (pSS).

METHODS

Twenty-eight patients with pSS according to the American-European Consensus Criteria were included in the study. Gastric emptying was evaluated by the octanoate breath test from which half-time (t(half)) and lag-time (t(lag)) were determined and compared with the results from 50 healthy controls. Autonomic nervous function was evaluated by 5 objective autonomic reflex tests (ART) and by the Autonomic Symptom Profile (ASP) questionnaire evaluating AD symptoms. These results were compared with previously investigated healthy ART controls and population-based ASP controls. Patients were also assessed regarding symptoms of functional bowel syndrome.

RESULTS

The t(half) and the t(lag) were significantly prolonged in patients compared to controls. Forty-three percent of patients with pSS presented signs of IGE and 29% fulfilled the criteria for gastroparesis. Significant correlations were found between t(lag) and increased levels of IgG (p = 0.02) and erythrocyte sedimentation rate (ESR; p = 0.01). In addition, rheumatoid factor (RF) seropositives showed objective signs of IGE to a greater extent than RF seronegatives. No associations between IGE, ART variables, ASP variables, or gastrointestinal symptoms were found.

CONCLUSION

IGE was common in pSS. Associations with inflammatory and serological features of pSS could imply immunological mechanisms behind the IGE. Objective signs of IGE were not associated with objective signs or subjective symptoms of AD or functional bowel syndrome.

Impact of autonomic dysfunction on inflammatory bowel disease

Functional symptoms are common in patients with inflammatory bowel disease (IBD). The autonomic nervous system has been proposed to be involved in the pathogenesis of IBD. Autonomic dysfunction (AD) is associated with systemic manifestations and altered gut motility that may contributed to functional symptoms.

AIM

To examine the impact of clinically manifest AD on patients with IBD.

METHODS

This was a retrospective case-control study from a single tertiary referral IBD center. The cases comprised 43 IBD patients with AD diagnosed using a standardized battery of tests. Three disease-matched controls were selected for each case. We performed multivariate regression to compare health-related quality of life (SIBDQ), disease activity scores, and healthcare utilization.

RESULTS

Female sex (83.7% vs. 53.5%, P<0.001) and psychiatric comorbidity (41.9% vs. 10.9%, P<0.001) were more common among IBD patients with AD than IBD controls. Small bowel transit times were significantly longer in cases (92.7 min) compared with controls (62.9 min, P=0.02). On multivariate analysis, AD was associated with a 7-point lower adjusted SIBDQ score compared with IBD controls [odds ratio (OR)-7.50; 95% confidence interval (CI), -12.0--3.03]. AD was also significantly associated with having more than 3 annual gastroenterology office visits (OR 2.84; 95% CI, 1.09-7.35), and 1 or more IBD-related medical hospitalizations (OR 2.49; 95% CI, 1.09-5.71).

CONCLUSIONS

Clinically manifest AD is associated with lower quality of life and higher healthcare utilization in IBD patients. They may represent a cohort at risk for worse outcomes.

Clinical and experimental evidence of sympathetic neural dysfunction during inflammatory bowel disease

1. Inflammatory bowel diseases (IBD) alter the function of the enteric nervous system and the sensory innervation of the gastrointestinal (GI) tract. Less is known about whether IBD also affects the sympathetic nervous system (SNS). Given the importance of the SNS in regulating GI function and possibly immune system activation, the present review examines the evidence of sympathetic dysfunction during IBD and its possible consequences. 2. Sympathetic axons within the GI tract innervate several cell types, including vascular myocytes, enteric neurons and immune cells. The major neurotransmitters released from sympathetic varicosities are noradrenaline, neuropeptide Y and ATP or a related purine. 3. Clinical studies of IBD patients have provided evidence of an association between IBD and axonal or demyelinating neuropathy. Assays of autonomic function suggest that ulcerative colitis and Crohn's disease, the two major forms of IBD, have contrasting effects on sympathetic neural activity. 4. Animal models of IBD have been used to examine the effects of these diseases on sympathetic neurophysiology. A decrease in the release of noradrenaline from sympathetic varicosities in inflamed and uninflamed regions of the GI tract has consistently been reported. Recent findings suggest that the decrease in neurotransmitter release may be due to inhibition of N-type voltage-gated Ca(2+) current in post-ganglionic sympathetic neurons. 5. Interest in the role of the SNS in IBD is rapidly increasing. However, much work needs to be done to enhance understanding of how SNS function is altered during IBD and what contribution, if any, these changes make to pathogenesis.

The relationship between intestinal microbiota and the central nervous system in normal gastrointestinal function and disease

Although many people are aware of the communication that occurs between the gastrointestinal (GI) tract and the central nervous system, fewer know about the ability of the central nervous system to influence the microbiota or of the microbiota's influence on the brain and behavior. Within the GI tract, the microbiota have a mutually beneficial relationship with their host that maintains normal mucosal immune function, epithelial barrier integrity, motility, and nutrient absorption. Disruption of this relationship alters GI function and disease susceptibility. Animal studies suggest that perturbations of behavior, such as stress, can change the composition of the microbiota; these changes are associated with increased vulnerability to inflammatory stimuli in the GI tract. The mechanisms that underlie these alterations are likely to involve stress-induced changes in GI physiology that alter the habitat of enteric bacteria. Furthermore, experimental perturbation of the microbiota can alter behavior, and the behavior of germ-free mice differs from that of colonized mice. Gaining a better understanding of the relationship between behavior and the microbiota could provide insight into the pathogenesis of functional and inflammatory bowel disorders.

[Neurological complications of inflammatory bowel disease]

Although ulcerative colitis and Crohn's disease have traditionally been considered to be inflammatory diseases limited to the gastrointestinal tract, it has been shown that both pathologies are frequently accompanied by various extraintestinal disorders. There is an increasing evidence that they may also manifest in the nervous system, including the peripheral and the central parts. Although some of these neurological complications have been known for a long time, such as cerebrovascular disease, vasculitis and autoinmune processes including neuropathies and cerebral demyelination, others have been recently described. With the exception of some of this complications such as the thromboembolism, evidence for a casual relationship relies merely on single case reports or case series. In this article, we try to review the existing evidence on neurological manifestations of both variants of inflammatory bowel disease.

Analysis of innervation of human mesenteric vessels in non-inflamed and inflamed bowel--a confocal and functional study

We investigated the distribution and density of perivascular nerves in human mesenteric arteries and veins and their responses to noradrenaline (NA), ATP and neuropeptide Y (NPY) in control (non-inflamed) and inflamed bowel, using confocal microscopy and in vitro pharmacology. The density of innervation at the adventitial-medial border of arteries and within the medial muscle coat of veins was increased in inflammatory bowel disease (IBD). Expression of markers for both sympathetic nerves and sensory-motor nerves was significantly increased in IBD. Calcitonin gene-related peptide-containing sensory-motor nerves were present in control arteries and IBD, but not in control veins. The density of 5-hydroxytryptamine-containing nerves was variable in controls, but consistently increased (three to four times) in IBD. Vasoactive intestinal peptide (VIP) expression increased (doubled) in arteries and veins. Arteries and veins contracted to NA and ATP, but only veins constricted to NPY. ATP contractions were reduced in arteries and veins in IBD, while contractions to NA were only slightly reduced. Neuropeptide Y induced significantly greater (20%) contractions of IBD veins. In summary, the density of sympathetic and sensory-motor innervation of both mesenteric arteries and veins was increased in IBD. Both 5-hydroxytryptamine and VIP immunoreactivity were also increased. The responses of both arteries and veins to ATP, and to a lesser extent NA, were reduced in IBD while responses to NPY were greater in veins. Decreased responses to ATP indicate changes in purinergic-mediated transmission in the pathological state.

Peripheral neuropathy and neurological disorders in an unselected Brazilian population-based cohort of IBD patients

BACKGROUND

Several neurological disorders have been described in inflammatory bowel disease (IBD) patients, but their exact frequency is unknown.

METHODS

We prospectively studied the prevalence of neurological disorders (especially peripheral neuropathy) in a group of 82 patients with Crohn's disease (CD, n = 31) or ulcerative colitis (UC, n = 51) from 2 Brazilian tertiary care university clinics and followed them through a period of at least 1 year. All patients were interviewed and had complete neurological evaluations.

RESULTS

Large-fiber sensory or sensorimotor polyneuropathy (PN) was observed in 16.1% of the CD and 19.6% of the UC patients. PN was usually mild, predominantly symmetric, and distal with axonal involvement. One patient had demyelinating PN at the diagnosis of CD. Mild carpal tunnel syndrome was common in female UC patients. Sensory symptoms without electromyography abnormalities, suggestive of small-fiber neuropathy or subclinical myelopathy, affected 29% and 11.8%, respectively. After excluding other known etiological or contributory factors for PN, 13.4% of the IBD patients had otherwise unexplained large-fiber or small-fiber PN (7.3% with large-fiber SM PN). Nondebilitating headache was the most common neurological complaint. Three patients had ischemic strokes, 5 were epileptic, and 1 transient chorea.

CONCLUSIONS

Neurological disorders, especially PN, are common in our Brazilian cohort of IBD patients. They are diverse, multifactorial, and more common in women. Despite the mild phenotype in most cases, attention should be given by the general practitioner and gastroenterologist since they are frequently undiagnosed. Further studies are necessary to confirm these findings in populations with different genetic and nutritional backgrounds.

The effect of the cholinergic anti-inflammatory pathway on experimental colitis

Inflammatory bowel diseases (IBD) are characterized by proinflammatory cytokines, tissue damage and loss of neuron in inflamed mucosa, which implies the cholinergic anti-inflammatory pathway may be destroyed during the process of inflammatory response. In the study, we identified the effect of cholinergic agonist as anabaseine (AN) and nicotinic receptor antagonist as chlorisondamine diiodide (CHD) on trinitrobenzene sulfonic acid (TNBS)-induced colitis, to investigate the potential therapeutic effect of the cholinergic anti-inflammatory pathway on IBD. Experimental colitis was induced by TNBS at day 1, 10 mug AN or 1.5 mug CHD was injected i.p. to mouse right after the induction of colitis, and repeated on interval day till the mice were sacrificed at day 8. Colonic inflammation was examined by histological analysis, myeloperoxidase (MPO) activity, and the production of tumour necrosis factor (TNF)-alpha in tissue. Lamina propria mononuclear cells (LPMC) were isolated, and NF-kappaB activation was detected by western blot. The mice with colitis treated by AN showed less tissue damage, less MPO activity, less TNF-alpha production in colon, and inhibited NF-kappaB activation in LPMC, compared with those mice with colitis untreated, whereas the mice with colitis treated by CHD showed the worst tissue damage, the highest MPO activity, the highest TNF-alpha level, and enlarged NF-kappaB activation in LPMC. Agonist of the cholinergic anti-inflammatory pathway inhibits colonic inflammatory response by downregulating the production of TNF-alpha, and inhibiting NF-kappaB activation, which suggests that modulating the cholinergic anti-inflammatory pathway may be a new potential management for IBD.

A comparison of autonomic function in patients with inflammatory bowel disease and in healthy controls

We evaluated autonomic function, symptoms and psychological parameters in patients with ulcerative colitis (UC), Crohn's disease (CD) and matched controls to assess whether UC patients have greater basal sympathetic autonomic activity. Outpatients with UC (n = 15), CD (n = 13) and healthy controls (n = 28) underwent spectral analysis of heart rate variability to assess cardiac autonomic function, a methacholine challenge to assess cholinergic pulmonary responsiveness, and questionnaires assessing disease severity, anxiety and depression. UC but not CD patients had greater sympathetic activity than controls with increased absolute (6600 vs 5884; P = 0.04) and relative (62.8%vs 54.8%; P = 0.02) low frequency areas. This was not because of increased overall autonomic nervous system (ANS) activation and was independent of disease activity. In UC patients, trait (personality-related) anxiety correlated strongly with disease symptoms (R = 0.84; P < 0.001) and quality of life (R = -0.81; P < 0.001) while situational (state) anxiety did not. In CD patients, ANS measures were similar to controls and disease activity was unrelated to psychological measures. Cholinergic pulmonary responsiveness was normal in both UC and CD patients. UC patients have an increased sympathetic ANS activity which is independent of symptom severity. In these patients symptom severity is strongly associated with measures of personality related (but not current) anxiety.

The protective effect of the vagus nerve in a murine model of chronic relapsing colitis

The vagus nerve inhibits the response to systemic administration of endotoxin, and we have recently extended this observation to show that the vagus attenuates acute experimental colitis in mice. The purpose of the present study was to determine whether there is a tonic counterinflammatory influence of the vagus on colitis maintained over several weeks. We assessed disease activity index, macroscopic and histological damage, myeloperoxidase (MPO) activity, and Th1 and Th2 cytokine profiles in chronic colitis induced by administration of dextran sodium sulfate (DSS) in drinking water for three cycles during 5 days with 11 days of rest between each cycle (DSS 3, 2, 2%) in healthy and vagotomized C57BL/6 mice and in mice deficient in macrophage-colony stimulating factor (M-CSF). A pyloroplasty was performed in vagotomized mice. Vagotomy accelerated the onset and the severity of inflammation during the first and second but not the third cycle. Although macroscopic scores were not significantly changed, histological scores as well as MPO activity and colonic tissue levels of IL-1alpha, TNF-alpha, IFN-gamma, and IL-18 but not IL-4 were significantly increased in vagotomized mice compared with sham-operated mice that received DSS. In control mice (without colitis), vagotomy per se did not affect any inflammatory marker. Vagotomy had no effect on the colitis in M-CSF-derived macrophage-deficient mice. These results indicate that the vagus protects against acute relapses on a background of chronic inflammation. Identification of the molecular mechanisms underlying the protective role of parasympathetic nerves opens a new therapeutic avenue for the treatment of acute relapses of chronic inflammatory bowel disease.

Vagus nerve integrity and experimental colitis

Previous studies have identified a counterinflammatory vagal reflex in the context of endotoxic shock. We have extended this observation to show that the vagus confers protection against acute (5 days) colitis induced by dextran sodium sulfate (DSS) or by dinitrobenzene sulfonic acid (DNBS). We have shown that this is mediated via macrophages and involves the suppression of proinflammatory cytokines. In this study, we have examined whether the vagal integrity confers long-lasting protection by studying DNBS- and DSS-induced inflammatory responses in the colon at 9 to 61 days postvagotomy. The integrity of vagotomy was confirmed at all time points using CCK-induced satiety. As previously described in a DNBS and DSS model, vagotomy associated with the pyloroplasty increased all indices of inflammation. Vagotomy increased the disease activity index as well as the macroscopic and histological scores by 75 and 41%, respectively. In addition, myeloperoxidase (MPO) activity, serum levels of C-reactive protein (CRP), and colonic tissue levels of proinflammatory cytokine increased when colitis was induced 9 days postvagotomy. However, these increases in inflammatory indices were substantially diminished in mice with colitis induced 21, 33, and 61 days postvagotomy. This was accompanied by an increased production of interleukin-10, transforming growth factor-beta, Forkhead Box P3 (FOXP3) staining in colonic tissue, and serum corticosterone. These findings indicate that although vagal integrity is an important protective factor, other counterinflammatory mechanisms come into play if vagal integrity is compromised beyond 2 wk.

Subclinical sympathetic neuropathy appears early in the course of Crohn's disease

BACKGROUND

We have previously demonstrated that patients with Crohn's disease (CD) of long duration have signs of autonomic neuropathy. The aim of this study was to examine whether autonomic neuropathy is an early manifestation of CD, or a sign appearing late in the course.

METHODS

Twenty patients, median age 40 years, with a short duration of CD were included. Examination of autonomic reflexes included heart rate reaction to tilt (acceleration index - AI, brake index - BI) and heart rate variation to deep-breathing (expiration/inspiration index-E/I). Seven years later the same examinations were repeated, and in addition we examined the vasoconstriction response to indirect cooling by laser Doppler (vasoconstriction-index - VAC-index). The results were compared with healthy individuals.

RESULTS

There was no difference in the blood pressure between controls and the patients with CD at rest, but eight minutes after tilt, the systolic blood pressure was lowered in patients compared to controls, both at the first assessment (p = 0.016) and after seven years (p = 0.042). The change in systolic blood pressure between rest and eight minutes after tilt was not significant at the first assessment, while a significant change compared to controls was observed seven years later (p = 0.028). This indicates a progressive dysfunction. There were no differences in E/I, AI, BI or VAC indexes between patients and controls.

CONCLUSION

Patients with CD suffer from autonomic neuropathy early in their disease, suggesting involvement of many different organ systems in this entity.

The vagus nerve: a tonic inhibitory influence associated with inflammatory bowel disease in a murine model

BACKGROUND & AIMS

The recently proposed Inflammatory Reflex describes an interaction between the vagus nerve and peripheral macrophages, resulting in attenuation of proinflammatory cytokine release in response to systemic exposure to bacterial endotoxin. The purpose of this study was to determine whether a similar vagus/macrophage axis modulates the inflammatory responses in the colon in mice.

METHODS

We assessed the Disease Activity Index (DAI), macroscopic and histologic damage, serum amyloid-P level, and myeloperoxidase activity in colitis induced by administration of dextran sodium sulfate (DSS) in healthy and vagotomized C57BL/6 and in mice deficient in macrophage-colony stimulating factor (M-CSF)-induced and in hapten-induced colitis. A pyloroplasty was performed in vagotomized mice.

RESULTS

DAI, macroscopic and histologic scores, myeloperoxidase activity, levels of serum amyloid-P, and colonic tissue levels of interleukin (IL)-1beta, IL-6, and tumor necrosis factor-alpha were increased significantly in vagotomized mice 5 days post-DSS and 3 days after hapten-induced colitis compared with sham-operated mice that received DSS or the hapten. Pretreatment with nicotine significantly decreased each of these markers in vagotomized mice with DSS colitis, and all markers except DAI and IL-6 in sham-operated DSS-treated mice. Conversely, hexamethonium treatment significantly increased each of these markers in the sham-operated DSS-treated mice. Vagotomy had no effect on the colitis in M-CSF-deficient mice.

CONCLUSIONS

The vagus nerve plays a counterinflammatory role in acute colitis via a macrophage-dependent mechanism, involving hexamethonium-sensitive nicotinic receptors. The identification of a counterinflammatory neural pathway would open new therapeutic avenues for treating acute exacerbations of inflammatory bowel disease.