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

Effects of psychological stress on inflammatory bowel disease via affecting the microbiota-gut-brain axis

ABSTRACT

Inflammatory bowel disease (IBD) is an idiopathic intestinal inflammatory condition with chronic and relapsing manifestations and is characterized by a disturbance in the interplay between the intestinal microbiota, the gut, and the brain. The microbiota-gut-brain axis involves interactions among the nervous system, the neuroendocrine system, the gut microbiota, and the host immune system. Increasing published data indicate that psychological stress exacerbates the severity of IBD due to its negative effects on the microbiota-gut-brain axis, including alterations in the stress response of the hypothalamic-pituitary-adrenal (HPA) axis, the balance between the sympathetic nervous system and vagus nerves, the homeostasis of the intestinal flora and metabolites, and normal intestinal immunity and permeability. Although the current evidence is insufficient, psychotropic agents, psychotherapies, and interventions targeting the microbiota-gut-brain axis show the potential to improve symptoms and quality of life in IBD patients. Therefore, further studies that translate recent findings into therapeutic approaches that improve both physical and psychological well-being are needed.

A biodegradable capacitive-coupling neurostimulator for wireless electroceutical treatment of inflammatory bowel diseases

Electroceuticals based on peripheral nerve stimulation offer promising treatment for refractory inflammatory diseases such as inflammatory bowel diseases (IBDs). For pediatric IBD (PIBD) patients, wireless, biodegradable miniaturized bioelectronic devices are crucial to prevent neural damage and support neural development during and after therapy. Here we demonstrate a battery-free, miniaturized neurostimulator based on biodegradable materials and capacitive-coupling wireless power transfer. The biodegradable capacitive-coupling (BCC) neurostimulator consists of molybdenum (Mo) electronic components and self-healing biodegradable polyurethane elastomer (SBPUE) encapsulations. The self-healing property of SBPUE enables a stable neural interface. Capacitive coupling wirelessly transfers high-frequency electric fields through a single capacitor between wearable transmitters and implanted BCC neurostimulators. Programmed electrical stimulation of the vagus nerve alleviates PIBD symptoms by restoring CD4+ T cell balance, enhancing anti-inflammatory effects and suppressing pro-inflammatory effects in the intestines.

Targeting the cholinergic anti-inflammatory pathway: an innovative strategy for treating diseases

The cholinergic anti-inflammatory pathway (CAP) is comprised of the vagus nerve, acetylcholine, nicotinic acetylcholine receptors, the spleen, and the splenic nerve. It represents a sophisticated neuroimmune axis that critically regulates the crosstalk between the nervous system and the immune response via the vagus nerve. Here, we provided a nuanced exploration of the CAP's role in curbing inflammatory processes and its broad therapeutic potential across a spectrum of diseases. We meticulously dissect the intricate mechanisms by which the CAP modulates key signaling cascades, including the NF-κB, JAK2/STAT3, MAPK/ERK, PI3K/AKT, COX2/PGE2, and NRF2/HO-1 pathways, which are quintessential in the pathogenesis of various conditions. Additionally, we also summarized the CAP's profound implications in the management of inflammatory diseases, neurodegenerative disorders, metabolic syndromes, and oncological malignancies, elucidating its capacity to mitigate disease severity and progression through sophisticated immune modulation. The modulation of the CAP is suggested as a novel strategy that could potentially transform treatment approaches for a variety of conditions. However, the precise cellular and molecular underpinnings of the CAP's effects, as well as its translatability to clinical settings, remain subjects of ongoing investigation. The review calls for further research to demystify the mechanisms of the CAP and to harness its therapeutic potential fully, with the aim of developing innovative and efficacious treatment modalities that exploit the pathway's unique attributes.

Applications of transcranial direct current stimulation over vagus nerve on dysphagia after stroke

Vagus nerve stimulation (VNS) has been commonly employed for the functional rehabilitation of stroke patients. This study aimed to investigate the therapeutic effects of transcranial direct current stimulation on the vagus nerve (TDCSVN) in improving dysphagia in stroke patients. Patients experiencing dysphagia following a stroke were diagnosed with dysphagia by a water swallow test. Swallowing function was evaluated with the standard swallowing scale score and the functional dysphagia scale. Serum levels of interleukin (IL)-1β and IL-8 were measured with enzyme-linked immunosorbent assays. TDCSVN treatment resulted in a significantly greater reduction in both the standard swallowing scale and functional dysphagia scale scores compared to conventional treatment. Furthermore, TDCSVN treatment led to a notable increase in hemoglobin and albumin levels, suggesting a more substantial improvement in dysphagia compared to conventional methods. Additionally, TDCSVN treatment was more effective in decreasing serum levels of IL-1β and IL-8 in dysphagic patients after a stroke. TDCSVN treatment demonstrated a significant inhibitory effect on inflammatory cytokines, resulting in a more pronounced improvement in dysphagia among stroke patients.NEW & NOTEWORTHY The present study demonstrates that transcranial direct current stimulation on the vagus nerve (TDCSVN) treatment shows a significant inhibitory effect on the production of inflammatory factors, resulting in a more pronounced improvement in dysphagia among stroke patients.

Bioelectronic Medicines-A Novel Approach of Therapeutics in Current Epoch

BACKGROUND

Bioelectronic medicines aim to diagnose and treat a wide range of illnesses and ailments, including cancer, rheumatoid arthritis, inflammatory bowel disease, obesity, diabetes, asthma, paralysis, blindness, bleeding, ischemia, organ transplantation, cardiovascular disease, and neurodegenerative diseases. The focus of bioelectronic medicine is on electrical signaling of the nervous system. Understanding the nervous system's regulatory roles and developing technologies that record, activate, or inhibit neural signaling to influence particular biological pathways.

OBJECTIVE

Bioelectronic medicine is an emerging therapeutic option with the interconnection between molecular medicine, neuroscience, and bioengineering. The creation of nerve stimulating devices that communicate with both the central and peripheral nervous systems has the potential to completely transform how we treat disorders. Although early clinical applications have been largely effective across entire nerves, the ultimate goal is to create implantable, miniature closed-loop systems that can precisely identify and modulate individual nerve fibers to treat a wide range of disorders.

METHODOLOGY

The data bases such as PubMed, and Clinicaltrial.gov.in were searched for scientific research, review and clinical trials on bioelectronic medicine.

CONCLUSION

The field of bioelectronic medicine is trending at present. In recent years, researchers have extended the field's applications, undertaken promising clinical trials, and begun delivering therapies to patients, thus creating the groundwork for significant future advancements. Countries and organizations must collaborate across industries and regions to establish an atmosphere and guidelines that foster the advancement of the field and the fulfillment of its prospective advantages.

Exploring the efficacy of Transcutaneous Auricular Vagus nerve stimulation (taVNS) in modulating local and systemic inflammation in experimental models of colitis

BACKGROUND

Current inflammatory bowel disease (IBD) treatments often fail to achieve lasting remission and have adverse effects. Vagus nerve stimulation (VNS) offers a promising therapy due to its anti-inflammatory effects. Its invasive nature, however, has led to the development of non-invasive methods like transcutaneous auricular VNS (taVNS). This study assesses taVNS's impact on acute colitis progression, inflammatory, anti-inflammatory, and apoptosis-related markers.

METHODS

Male C57BL/6 mice (11-12 weeks) were used for dextran sulfate sodium (DSS)- and dinitrobenzene sulfonic acid (DNBS)-induced colitis studies. The administration of taVNS or no stimulation (anesthesia without stimulation) for 10 min per mouse began one day before colitis induction and continued daily until sacrifice. Ulcerative colitis (UC)-like colitis was induced by administering 5% DSS in drinking water for 5 days, after which the mice were sacrificed. Crohn's disease (CD)-like colitis was induced through a single intrarectal injection of DNBS/ethanol, with the mice sacrificed after 3 days. Disease activity index (DAI), macroscopic evaluations, and histological damage were assessed. Colon, spleen, and blood samples were analyzed via qRT-PCR and ELISA. One-way or two-way ANOVA with Bonferroni and Šídák tests were applied.

RESULTS

taVNS improved DAI, macroscopic, and histological scores in DSS colitis mice, but only partially mitigated weight loss and DAI in DNBS colitis mice. In DSS colitis, taVNS locally decreased colonic inflammation by downregulating pro-inflammatory markers (IL-1β, TNF-α, Mip1β, MMP 9, MMP 2, and Nos2) at the mRNA level and upregulating anti-inflammatory TGF-β in non-colitic conditions at both mRNA and protein levels and IL-10 mRNA levels in both non-colitic and colitic conditions. Systemically, taVNS decreased splenic TNF-α in non-colitic mice and increased serum levels of TGF-β in colitic mice and splenic levels in non-colitic and colitic mice. Effects were absent in DNBS-induced colitis. Additionally, taVNS decreased pro-apoptotic markers (Bax, Bak1, and caspase 8) in non-colitic and colitic conditions and increased the pro-survival molecule Bad in non-colitic mice.

CONCLUSIONS

This study demonstrates that taVNS has model-dependent local and systemic effects, reducing inflammation and apoptosis in UC-like colitis while offering protective benefits in non-colitic conditions. These findings encourage further research into underlying mechanisms and developing adjunct therapies for UC.

Projections from subfornical organ to bed nucleus of the stria terminalis modulate inflammation-induced anxiety-like behaviors in mice

Peripheral inflammation is closely related to the pathogenesis of sickness behaviors and psychiatric disorders such as anxiety and depression. The circumventricular organs (CVOs) are important brain sites to perceive peripheral inflammatory signals, but few studies have reported their role in inflammation-induced anxiety or depression. Using a mouse model of lipopolysaccharide (LPS)-induced inflammation, we identified a previously unreported role of the subfornical organ (SFO), one of the CVOs, in combating inflammation-induced anxiety. LPS treatment induced anxiety-like and sickness behaviors in mice. Although both the SFO and the organum vasculosum of the lamina terminalis (a CVO) neurons were activated after LPS treatment, only manipulating SFO neurons modulated LPS-induced anxiety-like behaviors. Activating or inhibiting SFO neurons alleviated or aggravated LPS-induced anxiety-like behaviors. In addition, SFO exerted this effect through glutamatergic projections to the bed nucleus of the stria terminalis. Manipulating SFO neurons did not affect LPS-induced sickness behaviors. Thus, we uncovered an active role of SFO neurons in counteracting peripheral inflammation-induced anxiety.

Non-invasive vagus nerve stimulation in anti-inflammatory therapy: mechanistic insights and future perspectives

Non-invasive vagus nerve stimulation (VNS) represents a transformative approach for managing a broad spectrum of inflammatory and autoimmune conditions, including rheumatoid arthritis and inflammatory bowel disease. This comprehensive review delineates the mechanisms underlying VNS, emphasizing the cholinergic anti-inflammatory pathway, and explores interactions within the neuro-immune and vagus-gut axes based on both clinical outcomes and pre-clinical models. Clinical applications have confirmed the efficacy of VNS in managing specific autoimmune diseases, such as rheumatoid arthritis, and chronic inflammatory conditions like inflammatory bowel disease, showcasing the variability in stimulation parameters and patient responses. Concurrently, pre-clinical studies have provided insights into the potential of VNS in modulating cardiovascular and broader inflammatory responses, paving the way for its translational application in clinical settings. Innovations in non-invasive VNS technology and precision neuromodulation are enhancing its therapeutic potential, making it a viable option for patients who are unresponsive to conventional treatments. Nonetheless, the widespread adoption of this promising therapy is impeded by regulatory challenges, patient compliance issues, and the need for extensive studies on long-term efficacy and safety. Future research directions will focus on refining VNS technology, optimizing treatment parameters, and exploring synergistic effects with other therapeutic modalities, which could revolutionize the management of chronic inflammatory and autoimmune disorders.

Caloric restriction mimetics improve gut microbiota: a promising neurotherapeutics approach for managing age-related neurodegenerative disorders

The gut microbiota (GM) produces various molecules that regulate the physiological functionality of the brain through the gut-brain axis (GBA). Studies suggest that alteration in GBA may lead to the onset and progression of various neurological dysfunctions. Moreover, aging is one of the prominent causes that contribute to the alteration of GBA. With age, GM undergoes a shift in population size and species of microflora leading to changes in their secreted metabolites. These changes also hamper communications among the HPA (hypothalamic-pituitary-adrenal), ENS (enteric nervous system), and ANS (autonomic nervous system). A therapeutic intervention that has recently gained attention in improving health and maintaining communication between the gut and the brain is calorie restriction (CR), which also plays a critical role in autophagy and neurogenesis processes. However, its strict regime and lifelong commitment pose challenges. The need is to produce similar beneficial effects of CR without having its rigorous compliance. This led to an exploration of calorie restriction mimetics (CRMs) which could mimic CR's functions without limiting diet, providing long-term health benefits. CRMs ensure the efficient functioning of the GBA through gut bacteria and their metabolites i.e., short-chain fatty acids, bile acids, and neurotransmitters. This is particularly beneficial for elderly individuals, as the GM deteriorates with age and the body's ability to digest the toxic accumulates declines. In this review, we have explored the beneficial effect of CRMs in extending lifespan by enhancing the beneficial bacteria and their effects on metabolite production, physiological conditions, and neurological dysfunctions including neurodegenerative disorders.

Heart rate variability and autonomic nervous system imbalance: Potential biomarkers and detectable hallmarks of aging and inflammaging

The most cutting-edge issue in the research on aging is the quest for biomarkers that transcend molecular and cellular domains to encompass organismal-level implications. We recently hypothesized the role of Autonomic Nervous System (ANS) imbalance in this context. Studies on ANS functions during aging highlighted an imbalance towards heightened sympathetic nervous system (SNS) activity, instigating a proinflammatory milieu, and attenuated parasympathetic nervous system (PNS) function, which exerts anti-inflammatory effects via the cholinergic anti-inflammatory pathway (CAP) and suppression of the hypothalamic-pituitary-adrenal (HPA) axis. This scenario strongly suggests that ANS imbalance can fuel inflammaging, now recognized as one of the most relevant risk factors for age-related disease development. Recent recommendations have increasingly highlighted the need for actionable strategies to improve the quality of life for older adults by identifying biomarkers that can be easily measured, even in asymptomatic individuals. We advocate for considering ANS imbalance as a biomarker of aging and inflammaging. Measures of ANS imbalance, such as heart rate variability (HRV), are relatively affordable, non-invasive, and cost-effective, making this hallmark easily diagnosable. HRV gains renewed significance within the aging research landscape, offering a tangible link between pathophysiological perturbations and age-related health outcomes.

Nutraceuticals in the management of autonomic function and related disorders: A comprehensive review

Nutraceuticals have been described as phytocomplexes when derived from foods of plant origin or a pool of secondary metabolites when derived from foods of animal origin, which are concentrated and administered in an appropriate form and can promote beneficial health effects in the prevention/treatment of diseases. Considering that pharmaceutical medications can cause side effects, there is a growing interest in using nutraceuticals as an adjuvant therapeutic tool for several disorders involving autonomic dysfunction, such as obesity, atherosclerosis and other cardiometabolic diseases. This review summarizes and discusses the evidence from the literature on the effects of various nutraceuticals on autonomic control, addressing the gut microbiota modulation, production of secondary metabolites from bioactive compounds, and improvement of physical and chemical properties of cell membranes. Additionally, the safety of nutraceuticals and prospects are discussed. Probiotics, resveratrol, quercetin, curcumin, nitrate, inositol, L-carnosine, and n-3 polyunsaturated fatty acids (n-3 PUFAs) are among the nutraceuticals most studied to improve autonomic dysfunction in experimental animal models and clinical trials. Further human studies are needed to elucidate the effects of nutraceuticals formulated of multitarget compounds and their underlying mechanisms of action, which could benefit conditions involving autonomic dysfunction.

GSK3β Substrate-competitive Inhibitors Regulate the gut Homeostasis and Barrier Function to Inhibit Neuroinflammation in Scopolamine-induced Alzheimer's Disease Model Mice

Alzheimer's disease (AD) is a neurodegenerative disease mainly characterized by cognitive impairment. Glycogen synthase kinase 3 (GSK3β) is a potential therapeutic target against AD. Isoorientin (ISO), a GSK3β substrate competitive inhibitor, plays anti-AD effects in in vitro and in vivo AD model. TFGF-18 is an ISO synthetic analog with improved potency, but its neuroprotective effect in vivo remains to be elucidated, and the underlying mechanisms of GSK3β inhibitor against AD need to be clarified. This study investigated the TFGF-18 and ISO effects on gut homeostasis and neuroinflammation in scopolamine (SCOP)-induced AD mice. And the protection on barrier function was observed in in vitro blood-brain barrier (BBB) model of mouse brain microvascular endothelial cells (bEnd.3). The results show that TFGF-18 and ISO improved cognitive function in SCOP-induced mice, and inhibited cholinergic system disorders and inflammation in the brain and intestine, decreased the level of lipopolysaccharides (LPS) in serum and intestine, protected the diversity and balance of intestinal microbiome, increased the expressions of tight junction protein (ZO-1, occludin), brain derived neurotrophic factor (BDNF) and glial cell-derived neurotrophic factor (GDNF) in the mouse brain and intestine. In addition, TFGF-18 and ISO protected against barrier damage in LPS-stimulated BBB model of bEnd.3 cells in vitro. TFGF-18 and ISO increased the ratio of p-GSK3β/GSK3β, suppressed toll-like receptors 4 (TLR-4) expression and nuclear factor kappa-B (NF-κB) activation in vivo and in vitro, and increased the expressions of β-catenin, nuclear factor erythroid 2-related factor 2 (Nrf2) and heme oxygenase-1 (HO-1) in vitro. In conclusion, The GSK3β inhibitors TFGF-18 and ISO modulate the gut homeostasis and barrier function to inhibit neuroinflammation and attenuate cognitive impairment by regulating NF-κB, β-catenin and Nrf2/HO-1 pathways.

A Reappraisal of the Pathophysiology of Cushing Ulcer: A Narrative Review

In 1932, Harvey Cushing described peptic ulceration secondary to raised intracranial pressure and attributed this to vagal overactivity, causing excess gastric acid secretion. Cushing ulcer remains a cause of morbidity in patients, albeit one that is preventable. This narrative review evaluates the evidence pertaining to the pathophysiology of neurogenic peptic ulceration. Review of the literature suggests that the pathophysiology of Cushing ulcer may extend beyond vagal mechanisms for several reasons: (1) clinical and experimental studies have shown only a modest increase in gastric acid secretion in head-injured patients; (2) increased vagal tone is found in only a minority of cases of intracranial hypertension, most of which are related to catastrophic, nonsurvivable brain injury; (3) direct stimulation of the vagus nerve does not cause peptic ulceration, and; (4) Cushing ulcer can occur after acute ischemic stroke, but only a minority of strokes are associated with raised intracranial pressure and/or increased vagal tone. The 2005 Nobel Prize in Medicine honored the discovery that bacteria play key roles in the pathogenesis of peptic ulcer disease. Brain injury results in widespread changes in the gut microbiome in addition to gastrointestinal inflammation, including systemic upregulation of proinflammatory cytokines. Alternations in the gut microbiome in patients with severe traumatic brain injury include colonization with commensal flora associated with peptic ulceration. The brain-gut-microbiome axis integrates the central nervous system, the enteric nervous system, and the immune system. Following the review of the literature, we propose a novel hypothesis that neurogenic peptic ulcer may be associated with alterations in the gut microbiome, resulting in gastrointestinal inflammation leading to ulceration.

Clinical safety and feasibility of a novel implantable neuroimmune modulation device for the treatment of rheumatoid arthritis: initial results from the randomized, double-blind, sham-controlled RESET-RA study

BACKGROUND

Rheumatoid arthritis (RA) is a chronic inflammatory autoimmune disease that causes persistent synovitis, bone damage, and progressive joint destruction. Neuroimmune modulation through electrical stimulation of the vagus nerve activates the inflammatory reflex and has been shown to inhibit the production and release of inflammatory cytokines and decrease clinical signs and symptoms in RA. The RESET-RA study was designed to determine the safety and efficacy of an active implantable device for treating RA.

METHODS

The RESET-RA study is a randomized, double-blind, sham-controlled, multi-center, two-stage pivotal trial that enrolled patients with moderate-to-severe RA who were incomplete responders or intolerant to at least one biologic or targeted synthetic disease-modifying anti-rheumatic drug. A neuroimmune modulation device (SetPoint Medical, Valencia, CA) was implanted on the left cervical vagus nerve within the carotid sheath in all patients. Following post-surgical clearance, patients were randomly assigned (1:1) to active stimulation or non-active (control) stimulation for 1 min once per day. A predefined blinded interim analysis was performed in patients enrolled in the study's initial stage (Stage 1) that included demographics, enrollment rates, device implantation rates, and safety of the surgical procedure, device, and stimulation over 12 weeks of treatment.

RESULTS

Sixty patients were implanted during Stage 1 of the study. All device implant procedures were completed without intraoperative complications, infections, or surgical revisions. No unanticipated adverse events were reported during the perioperative period and at the end of 12 weeks of follow-up. No study discontinuations were due to adverse events, and no serious adverse events were related to the device or stimulation. Two serious adverse events were related to the implantation procedure: vocal cord paresis and prolonged hoarseness. These were reported in two patients and are known complications of surgical implantation procedures with vagus nerve stimulation devices. The adverse event of vocal cord paresis resolved after vocal cord augmentation injections with filler and speech therapy. The prolonged hoarseness had improved with speech therapy, but mild hoarseness persists.

CONCLUSIONS

The surgical procedures for implantation of the novel neuroimmune modulation device for the treatment of RA were safe, and the device and its use were well tolerated.

TRIAL REGISTRATION

NCT04539964; August 31, 2020.

Analgesic Effects of Vagus Nerve Stimulation on Visceral Hypersensitivity: A Direct Comparison Between Invasive and Noninvasive Methods in Rats

OBJECTIVES

The aims of this study were to investigate analgesic effects of vagus nerve stimulation (VNS) on visceral hypersensitivity (VH) in a rodent model of functional dyspepsia (FD) and to compare invasive VNS with noninvasive auricular VNS (aVNS).

MATERIALS AND METHODS

Eighteen ten-day-old male rats were gavaged with 0.1% iodoacetamide (IA) or 2% sucrose solution for six days. After eight weeks, IA-treated rats were implanted with electrodes for VNS or aVNS (n = 6 per group). Different parameters, varying in frequency and stimulation duty cycle, were tested to find the best parameter based on the improvement of VH assessed by electromyogram (EMG) during gastric distension.

RESULTS

Compared with sucrose-treated rats, visceral sensitivity was increased significantly in IA-treated "FD" rats and ameliorated remarkably by VNS (at 40, 60, and 80 mm Hg; p ≤ 0.02, respectively) and aVNS (at 60 and 80 mm Hg; p ≤ 0.05, respectively) with the parameter of 100 Hz and 20% duty cycle. There was no significant difference in area under the curve of EMG responses between VNS and aVNS (at 60 and 80 mm Hg, both p > 0.05). Spectral analysis of heart rate variability revealed a significant enhancement in vagal efferent activity while applying VNS/aVNS compared with sham stimulation (p < 0.01). In the presence of atropine, no significant differences were noted in EMG after VNS/aVNS. Naloxone blocked the analgesic effects of VNS/aVNS.

CONCLUSIONS

VNS/aVNS with optimized parameter elicits ameliorative effects on VH, mediated by autonomic and opioid mechanisms. aVNS is as effective as direct VNS and has great potential for treating visceral pain in patients with FD.

Sacral Nerve Stimulation Alleviates Intestinal Inflammation Through Regulating the Autophagy of Macrophages and Activating the Inflammasome Mediated by a Cholinergic Antiinflammatory Pathway in Colitis Rats

BACKGROUND

Inflammatory bowel disease (IBD) is characterized by chronic progressive intestinal inflammation. Sacral nerve stimulation (SNS) ameliorates colon inflammation caused by IBD. The aim of this study was to investigate the antiinflammatory benefits of SNS in colitis rats and explore the roles of the cholinergic antiinflammatory pathway, macrophage autophagy, and nucleotide oligomerization domain-like receptor thermal protein domain associated protein 3 (NLRP3) inflammatory bodies.

MATERIALS AND METHODS

Rats were divided into four groups: healthy control, dextran sulfate sodium (DSS), DSS + sham-SNS, and DSS + SNS groups. An electrode was surgically placed in the right sacral nerve (S3) for stimulation. The disease activity index (DAI) score was recorded each day, and the degree of inflammatory injury was evaluated using hematoxylin and eosin staining. The alpha7 nicotinic acetylcholine receptor (α7nAChR) and autophagy- and NLRP3-related factors were assessed using immunofluorescence staining and Western blotting.

RESULTS

The DSS group showed a higher DAI score, colon shortening, upregulated proinflammatory action, and colon damage, and the DSS + SNS group showed significantly improved symptoms. The number of α7nAChR+ cells and the expression level of autophagy decreased in the DSS group but increased in the DSS + SNS group. Conversely, the DSS group showed increased activation of NLRP3 inflammatory bodies, whereas the DSS + SNS group showed decreased activation of NLRP3 inflammatory bodies.

CONCLUSION

In this study, SNS ameliorated colon inflammation by enhancing macrophage autophagy and inhibiting the activation of NLRP3 inflammatory bodies, which may be related to the opening of the cholinergic antiinflammatory pathway.

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.

Recent Advancements in Bioelectronic Medicine: A Review

Bioelectronic medicine is a multidisciplinary field that combines molecular medicine, neurology, engineering, and computer science to design devices for diagnosing and treating diseases. The advancements in bioelectronic medicine can improve the precision and personalization of illness treatment. Bioelectronic medicine can produce, suppress, and measure electrical activity in excitable tissue. Bioelectronic devices modify specific neural circuits using electrons rather than pharmaceuticals and uses of bioelectronic processes to regulate the biological processes underlining various diseases. This promotes the potential to address the underlying causes of illnesses, reduce adverse effects, and lower costs compared to conventional medication. The current review presents different important aspects of bioelectronic medicines with recent advancements. The area of bioelectronic medicine has a lot of potential for treating diseases, enabling non-invasive therapeutic intervention by regulating brain impulses. Bioelectronic medicine uses electricity to control biological processes, treat illnesses, or regain lost capability. These new classes of medicines are designed by the technological developments in the detection and regulation of electrical signaling methods in the nervous system. Peripheral nervous system regulates a wide range of processes in chronic diseases; it involves implanting small devices onto specific peripheral nerves, which read and regulate the brain signaling patterns to achieve therapeutic effects specific to the signal capacity of a particular organ. The potential for bioelectronic medicine field is vast, as it investigates for treatment of various diseases, including rheumatoid arthritis, diabetes, hypertension, paralysis, chronic illnesses, blindness, etc.

Effect of Vagus Nerve Stimulation on the GASH/Sal Audiogenic-Seizure-Prone Hamster

Vagus nerve stimulation (VNS) is an adjuvant neuromodulation therapy for the treatment of refractory epilepsy. However, the mechanisms behind its effectiveness are not fully understood. Our aim was to develop a VNS protocol for the Genetic Audiogenic Seizure Hamster from Salamanca (GASH/Sal) in order to evaluate the mechanisms of action of the therapy. The rodents were subject to VNS for 14 days using clinical stimulation parameters by implanting a clinically available neurostimulation device or our own prototype for laboratory animals. The neuroethological assessment of seizures and general behavior were performed before surgery, and after 7, 10, and 14 days of VNS. Moreover, potential side effects were examined. Finally, the expression of 23 inflammatory markers in plasma and the left-brain hemisphere was evaluated. VNS significantly reduced seizure severity in GASH/Sal without side effects. No differences were observed between the neurostimulation devices. GASH/Sal treated with VNS showed statistically significant reduced levels of interleukin IL-1β, monocyte chemoattractant protein MCP-1, matrix metalloproteinases (MMP-2, MMP-3), and tumor necrosis factor TNF-α in the brain. The described experimental design allows for the study of VNS effects and mechanisms of action using an implantable device. This was achieved in a model of convulsive seizures in which VNS is effective and shows an anti-inflammatory effect.

Gut liver brain axis in diseases: the implications for therapeutic interventions

Gut-liver-brain axis is a three-way highway of information interaction system among the gastrointestinal tract, liver, and nervous systems. In the past few decades, breakthrough progress has been made in the gut liver brain axis, mainly through understanding its formation mechanism and increasing treatment strategies. In this review, we discuss various complex networks including barrier permeability, gut hormones, gut microbial metabolites, vagus nerve, neurotransmitters, immunity, brain toxic metabolites, β-amyloid (Aβ) metabolism, and epigenetic regulation in the gut-liver-brain axis. Some therapies containing antibiotics, probiotics, prebiotics, synbiotics, fecal microbiota transplantation (FMT), polyphenols, low FODMAP diet and nanotechnology application regulate the gut liver brain axis. Besides, some special treatments targeting gut-liver axis include farnesoid X receptor (FXR) agonists, takeda G protein-coupled receptor 5 (TGR5) agonists, glucagon-like peptide-1 (GLP-1) receptor antagonists and fibroblast growth factor 19 (FGF19) analogs. Targeting gut-brain axis embraces cognitive behavioral therapy (CBT), antidepressants and tryptophan metabolism-related therapies. Targeting liver-brain axis contains epigenetic regulation and Aβ metabolism-related therapies. In the future, a better understanding of gut-liver-brain axis interactions will promote the development of novel preventative strategies and the discovery of precise therapeutic targets in multiple diseases.

Does a pickle a day keep Alzheimer's away? Fermented food in Alzheimer's disease: A review

Fermented food is commonly viewed as healthy, mostly due to its probiotic and digestion-enhancing properties and recently it has been examined with regard to the development of new therapeutic and preventive measures for Alzheimer's disease. Fermented food has been shown to have anti-inflammatory and antioxidant properties and to alter the gut microbiota. However, the exact pathogenesis of Alzheimer's disease is still unknown and its connections to systemic inflammation and gut dysbiosis, as potential targets of fermented food, require further investigation. Therefore, to sum up the current knowledge, this article reviews recent research on the pathogenesis of Alzheimer's disease with emphasis on the role of the gut-brain axis and studies examining the use of fermented foods. The analysis of the fermented food research includes clinical and preclinical in vivo and in vitro studies. The fermented food studies have shown promising effects on amyloid-β metabolism, inflammation, and cognitive impairment in animals and humans. Fermented food has great potential in developing new approaches to Alzheimer's disease treatment.

Linear and non‑linear indices of vagal nerve in relation to sex and inflammation in patients with Covid‑19

Hyperinflammation is one of the most important pathophysiological risk factors for poor prognosis in patients with coronavirus disease-2019 (Covid-19). Low vagal neuro-immune modulation can lead into this kind of immune dysregulation. The association between vagal activity, sex and inflammatory markers were investigated in patients with Covid-19. A total of 19 patients with Covid-19 were included in the present study. Vagus nerve activity was indexed by heart rate variability (HRV) derived from electrocardiogram at hospital admission. Linear HRV parameters included the root mean square of successive RR interval differences (RMSSD) and high-frequency HRV (HF-HRV), while non-linear parameters included 2 UV%. Immune/inflammatory parameters included C-reactive protein (CRP), interleukin-6 (IL-6), neutrophil/lymphocyte ratio (NLR), systemic inflammatory index (SII), and procalcitonin (PCT). It has been revealed that both linear HRV indices HF-HRV and RMSSD, are significantly negatively correlated with CRP and IL-6, independent of age. The non-linear index of 2 UV% is significantly negatively correlated with NLR and SII, which reflect subtle changes in the response of immunocompetent cells. Patients that received high-flow nasal oxygen therapy had significantly higher IL-6 and CRP levels and lower levels of HF-HRV and RMSSD. These patients also had a significantly longer length of stay in hospital (LOS) than patients receiving low-flow oxygen therapy. Men had higher plasma PCT levels and longer LOS in hospital than women, and PCT statistically explained (mediated) the association between sex and LOS. The present study showed different correlations of linear and non-linear vagal indexes of HRV and inflammatory markers in patients with Covid-19. Significant sex differences in certain inflammatory markers were also observed, which may very well verify previous findings of poor prognosis in men with Covid-19. HRV reflects a continuous interaction between the sympathetic and parasympathetic autonomic nervous systems, which are affected by mental or physical stress, and certain disease states. The increased sympathetic and decreased parasympathetic vagal tone contribute to a higher risk of diseases associated with inflammation, cardiovascular disease, cancer, pulmonary diseases and other pathologies, including infectious diseases such as Covid-19. The present study showed that higher RMSSD (a marker of vagal activity) in Covid-19 patients is associated with lower levels of inflammatory biomarkers, a lower need for treatment and is negatively correlated with intensive care unit admission, leading to a shorter hospital stay. These findings support the idea that activation of vagus nerve may help certain Covid-19 patients by reducing the cytokine storm and excessive inflammation.

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.

Neuroimmunomodulation of vagus nerve stimulation and the therapeutic implications

Vagus nerve stimulation (VNS) is a technology that provides electrical stimulation to the cervical vagus nerve and can be applied in the treatment of a wide variety of neuropsychiatric and systemic diseases. VNS exerts its effect by stimulating vagal afferent and efferent fibers, which project upward to the brainstem nuclei and the relayed circuits and downward to the internal organs to influence the autonomic, neuroendocrine, and neuroimmunology systems. The neuroimmunomodulation effect of VNS is mediated through the cholinergic anti-inflammatory pathway that regulates immune cells and decreases pro-inflammatory cytokines. Traditional and non-invasive VNS have Food and Drug Administration (FDA)-approved indications for patients with drug-refractory epilepsy, treatment-refractory major depressive disorders, and headaches. The number of clinical trials and translational studies that explore the therapeutic potentials and mechanisms of VNS is increasing. In this review, we first introduced the anatomical and physiological bases of the vagus nerve and the immunomodulating functions of VNS. We covered studies that investigated the mechanisms of VNS and its therapeutic implications for a spectrum of brain disorders and systemic diseases in the context of neuroimmunomodulation.

Acceleration of postoperative recovery with brief intraoperative vagal nerve stimulation mediated via the autonomic mechanism

Introduction

Postoperative recovery is largely dependent on the restoration of gastrointestinal motility. The aim of this study was to investigate the effects and mechanisms of intraoperative vagus nerve stimulation (iVNS) on postoperative recovery from abdominal surgery in rats.

Methods

The Nissen fundoplication surgery was performed on two groups of rats: sham-iVNS group and iVNS group (VNS was performed during surgery). Animal's behavior, eating, drinking and feces' conditions were monitored at specific postoperative days. Gastric slow waves (GSWs) and electrocardiogram (ECG) were recorded; blood samples were collected for the assessment of inflammatory cytokines.

Results

(1) iVNS shortened initiate times to water and food intake (p = 0.004) and increased the number of fecal pellets (p < 0.05, vs. sham-iVNS) and the percentage of water content in fecal pellets (p < 0.05). (2) iVNS improved gastric pace-making activity at 6 h after surgery reflected as a higher percentage of normal slow waves (p = 0.015, vs. sham-iVNS). (3) iVNS suppressed inflammatory cytokines at 24 h after surgery compared to sham-iVNS (TNF-α: p = 0.001; IL-1β: p = 0.037; IL-6: p = 0.002). (4) iVNS increased vagal tone compared to sham-iVNS group at 6 h and 24 h after the surgery (p < 0.05). Increased vagal tone was correlated with a faster postoperative recovery to start water and food intake.

Conclusion

Brief iVNS accelerates postoperative recovery by ameliorating postoperative animal behaviors, improving gastrointestinal motility and inhibiting inflammatory cytokines mediated via the enhanced vagal tone.

Electrical Sympathetic Neuromodulation Protects Bone Marrow Niche and Drives Hematopoietic Regeneration during Chemotherapy

The sympathetic nervous system (SNS) of the bone marrow regulates the regeneration and mobilization of hematopoietic stem cells. Chemotherapy can damage bone marrow SNS, which impairs hematopoietic regeneration and aggravates hematologic toxicities. This leads to long-term bone marrow niche damage and increases mortality in patients undergoing chemotherapy. Electrical neuromodulation has been used to improve functional recovery after peripheral nerve injury. This study demonstrates that electrical sympathetic neuromodulation (ESN) of bone marrow can protect the bone marrow niche from chemotherapy-induced injury. Using carboplatin-treated rats, the SNS via the sciatic nerve innervating the femoral marrow with the effective protocol for bone marrow sympathetic activation is electrically stimulated. ESN can mediate several hematopoietic stem cells maintenance factors and promote hematopoietic regeneration after chemotherapy. It also activates adrenergic signals and reduces the release of pro-inflammatory cytokines, particularly interleukin-1 β, which contribute to chemotherapy-related nerve injury. Consequently, the severity of chemotherapy-related leukopenia, thrombocytopenia, and mortality can be reduced by ESN. As a result, in contrast to current drug-based treatment, such as granulocyte colony-stimulating factor, ESN can be a disruptive adjuvant treatment by protecting and modulating bone marrow function to reduce hematologic toxicity during chemotherapy.

Lower ultra-short-term heart rate variability can predict worse mucosal healing in ulcerative colitis

BACKGROUND

Psychological stress has been proved to be a risk factor for exacerbation for ulcerative colitis (UC). However, traditional approaches of quantifying psychological stress using psychological scales are time-consuming and the results may not be comparable among patients with different educational levels and cultural backgrounds. Alternatively, heart rate variability (HRV) is an indicator for psychological stress and not biased by educational and cultural backgrounds.

AIMS

In this study, we try to explore the relationship between psychological stress and UC by analyzing the effect of ultra-short-term HRV on mucosal and histological remission status of UC.

METHODS

This is a retrospective case-control study on UC inpatients from 2018 through 2020. Ultra-short-term HRV were calculated using baseline electrocardiography. Patients were divided intocase and control groups according to their Mayo endoscopic scores or histological Geboes scores. Three variables of ultra-short-term HRV (the standard deviation of normal to normal R-R intervals (SDNN), the standard deviation of successive differences between adjacent normal to normal R-R intervals (SDSD), the root mean square of successive differences of normal to normal R-R intervals (RMSSD)) were compared between different groups. And for those variables with significant differences, we built univariate and multivariate logistic regressions to depict the relationship between HRV variables and remission status of UC.

RESULTS

All three HRV variables showed significant differences between the mucosal groups. However, none of them showed significant difference between the histological groups. In further logistic regression analyses, smaller RMSSD can predict severe mucosal healing status (OR = 5.21).

CONCLUSIONS

Lower ultra-short-term HRV (i.e. smaller RMSSD) is shown to positively correlate with worse mucosal healing status. However, ultra-short-term HRV cannot predict histological healing status according to our data.

Childhood maltreatment predicts physical health in college students

Objective: Childhood maltreatment (CM) is associated with physical health problems throughout the lifespan, yet more research is needed regarding the trajectory of health problems (e.g., onset of health risk indicators) in young adults. The current study examined whether college students self-reporting higher levels of CM exhibited poorer physical health outcomes. Method: Young adults in college (N = 100) completed a physical health assessment (heart rate, body mass index (BMI), blood pressure, blood sugar, waist circumference), self-reported measures of health (symptoms of illness), and CM during spring semester 2018. Results: CM scores predicted higher heart rate and increased symptoms of illness. Females with maltreatment history presented higher levels of obesity and more metabolic syndrome conditions than their peers. Conclusions: Findings support the importance of examining the trajectory of CM to chronic disease, as health risk indicators are present in young adults.

Prefrontal tDCS modulates autonomic responses in COVID-19 inpatients

BACKGROUND

maladaptive changes in the autonomic nervous system (ANS) have been observed in short and long-term phases of COVID-19 infection. Identifying effective treatments to modulate autonomic imbalance could be a strategy for preventing and reducing disease severity and induced complications.

OBJECTIVE

to investigate the efficacy, safety, and feasibility of a single session of bihemispheric prefrontal tDCS on indicators of cardiac autonomic regulation and mood of COVID-19 inpatients.

METHODS

patients were randomized to receive a single 30-minute session of bihemispheric active tDCS over the dorsolateral prefrontal cortex (2mA; n = 20) or sham (n = 20). Changes in time [post-pre intervention] in heart rate variability (HRV), mood, heart rate, respiratory rate, and oxygen saturation were compared between groups. Additionally, clinical worsening indicators and the occurrence of falls and skin injuries were evaluated. The Brunoni Adverse Effects Questionary was employed after the intervention.

RESULTS

there was a large effect size (Hedges' g = 0.7) of intervention on HRV frequency parameters, suggesting alterations in cardiac autonomic regulation. An increment in oxygen saturation was observed in the active group but not in the sham after the intervention (P = 0.045). There were no group differences regarding mood, incidence and intensity of adverse effects, no occurrence of skin lesions, falls, or clinical worsening.

CONCLUSIONS

a single prefrontal tDCS session is safe and feasible to modulate indicators of cardiac autonomic regulation in acute COVID-19 inpatients. Further research comprising a thorough assessment of autonomic function and inflammatory biomarkers is required to verify its potential to manage autonomic dysfunctions, mitigate inflammatory responses and enhance clinical outcomes.

Continuous vagus nerve stimulation exerts beneficial effects on rats with experimentally induced Parkinson's disease: Evidence suggesting involvement of a vagal afferent pathway

BACKGROUND

Vagus nerve stimulation (VNS) exerts neuroprotective and anti-inflammatory effects in preclinical models of central nervous system disorders, including Parkinson's disease (PD). VNS setting applied for experimental models is limited into single-time or intermittent short-duration stimulation. We developed a VNS device which could deliver continuous stimulation for rats. To date, the effects of vagal afferent- or efferent-selective stimulation on PD using continuous electrical stimulation remains to be determined.

OBJECTIVE

To investigate the effects of continuous and selective stimulation of vagal afferent or efferent fiber on Parkinsonian rats.

METHODS

Rats were divided into 5 group: intact VNS, afferent VNS (left VNS in the presence of left caudal vagotomy), efferent VNS (left VNS in the presence of left rostral vagotomy), sham, vagotomy. Rats underwent the implantation of cuff-electrode on left vagus nerve and 6-hydroxydopamine administration into the left striatum simultaneously. Electrical stimulation was delivered just after 6-OHDA administration and continued for 14 days. In afferent VNS and efferent VNS group, the vagus nerve was dissected at distal or proximal portion of cuff-electrode to imitate the selective stimulation of afferent or efferent vagal fiber respectively.

RESULTS

Intact VNS and afferent VNS reduced the behavioral impairments in cylinder test and methamphetamine-induced rotation test, which were accompanied by reduced inflammatory glial cells in substantia nigra with the increased density of the rate limiting enzyme in locus coeruleus. In contrast, efferent VNS did not exert any therapeutic effects.

CONCLUSION

Continuous VNS promoted neuroprotective and anti-inflammatory effect in experimental PD, highlighting the crucial role of the afferent vagal pathway in mediating these therapeutic outcomes.

A novel statistical methodology for quantifying the spatial arrangements of axons in peripheral nerves

A thorough understanding of the neuroanatomy of peripheral nerves is required for a better insight into their function and the development of neuromodulation tools and strategies. In biophysical modeling, it is commonly assumed that the complex spatial arrangement of myelinated and unmyelinated axons in peripheral nerves is random, however, in reality the axonal organization is inhomogeneous and anisotropic. Present quantitative neuroanatomy methods analyze peripheral nerves in terms of the number of axons and the morphometric characteristics of the axons, such as area and diameter. In this study, we employed spatial statistics and point process models to describe the spatial arrangement of axons and Sinkhorn distances to compute the similarities between these arrangements (in terms of first- and second-order statistics) in various vagus and pelvic nerve cross-sections. We utilized high-resolution transmission electron microscopy (TEM) images that have been segmented using a custom-built high-throughput deep learning system based on a highly modified U-Net architecture. Our findings show a novel and innovative approach to quantifying similarities between spatial point patterns using metrics derived from the solution to the optimal transport problem. We also present a generalizable pipeline for quantitative analysis of peripheral nerve architecture. Our data demonstrate differences between male- and female-originating samples and similarities between the pelvic and abdominal vagus nerves.

Auricular Vagus Nerve Stimulation Improves Visceral Hypersensitivity and Gastric Motility and Depression-like Behaviors via Vago-Vagal Pathway in a Rat Model of Functional Dyspepsia

Transcutaneous auricular vagus nerve stimulation was recently reported to have a therapeutic potential for functional dyspepsia (FD). This study aimed to explore the integrative effects and mechanisms of auricular vagus nerve stimulation (aVNS) in a rodent model of FD.

METHODS

We evaluated the effects of aVNS on visceral hypersensitivity, gastric motility and open field test (OFT) activity in iodoacetamide (IA)-treated rats. The autonomic function was assessed; blood samples and tissues were collected and analyzed by an enzyme-linked immunosorbent assay and western blot. Vagotomy was performed to investigate the role of vagal efferent nerve.

RESULTS

aVNS reduced the electromyography response to gastric distension, improved gastric emptying and increased the horizontal and vertical motion scores of the OFT in IA-treated rats. The sympathovagal ratio was increased in IA-treated rats but normalized with aVNS. The serum cytokines TNF-α, IL-6, IL-1β and NF-κBp65 were increased in IA-treated rats and decreased with aVNS. The hypothalamus-pituitary-adrenal axis was hyperactive in IA-treated rats but inhibited by aVNS. The expression of duodenal desmoglein 2 and occludin were all decreased in IA-treated rats and increased with aVNS but not sham-aVNS. Vagotomy abolished the ameliorating effects of aVNS on gastric emptying, horizontal motions, serum TNF-α and duodenal NF-κBp65.

CONCLUSION

aVNS improves gastric motility and gastric hypersensitivity probably by anti-inflammatory mechanisms via the vago-vagal pathways. A better understanding on the mechanisms of action involved with aVNS would lead to the optimization of the taVNS methodology and promote taVNS as a non-pharmacological alternative therapy for FD.

Transient Receptor Potential Ankyrin-1-expressing vagus nerve fibers mediate IL-1β induced hypothermia and reflex anti-inflammatory responses

BACKGROUND

Inflammation, the physiological response to infection and injury, is coordinated by the immune and nervous systems. Interleukin-1β (IL-1β) and other cytokines produced during inflammatory responses activate sensory neurons (nociceptors) to mediate the onset of pain, sickness behavior, and metabolic responses. Although nociceptors expressing Transient Receptor Potential Ankyrin-1 (TRPA1) can initiate inflammation, comparatively little is known about the role of TRPA1 nociceptors in the physiological responses to specific cytokines.

METHODS

To monitor body temperature in conscious and unrestrained mice, telemetry probes were implanted into peritoneal cavity of mice. Using transgenic and tissue specific knockouts and chemogenetic techniques, we recorded temperature responses to the potent pro-inflammatory cytokine IL-1β. Using calcium imaging, whole cell patch clamping and whole nerve recordings, we investigated the role of TRPA1 during IL-1β-mediated neuronal activation. Mouse models of acute endotoxemia and sepsis were used to elucidate how specific activation, with optogenetics and chemogenetics, or ablation of TRPA1 neurons can affect the outcomes of inflammatory insults. All statistical tests were performed with GraphPad Prism 9 software and for all analyses, P ≤ 0.05 was considered statistically significant.

RESULTS

Here, we describe a previously unrecognized mechanism by which IL-1β activates afferent vagus nerve fibers to trigger hypothermia, a response which is abolished by selective silencing of neuronal TRPA1. Afferent vagus nerve TRPA1 signaling also inhibits endotoxin-stimulated cytokine storm and significantly reduces the lethality of bacterial sepsis.

CONCLUSION

Thus, IL-1β activates TRPA1 vagus nerve signaling in the afferent arm of a reflex anti-inflammatory response which inhibits cytokine release, induces hypothermia, and reduces the mortality of infection. This discovery establishes that TRPA1, an ion channel known previously as a pro-inflammatory detector of cold, pain, itch, and a wide variety of noxious molecules, also plays a specific anti-inflammatory role via activating reflex anti-inflammatory activity.

Vagus Nerve Stimulation: A Personalized Therapeutic Approach for Crohn's and Other Inflammatory Bowel Diseases

Inflammatory bowel diseases, including Crohn's disease and ulcerative colitis, are incurable autoimmune diseases characterized by chronic inflammation of the gastrointestinal tract. There is increasing evidence that inappropriate interaction between the enteric nervous system and central nervous system and/or low activity of the vagus nerve, which connects the enteric and central nervous systems, could play a crucial role in their pathogenesis. Therefore, it has been suggested that appropriate neuroprosthetic stimulation of the vagus nerve could lead to the modulation of the inflammation of the gastrointestinal tract and consequent long-term control of these autoimmune diseases. In the present paper, we provide a comprehensive overview of (1) the cellular and molecular bases of the immune system, (2) the way central and enteric nervous systems interact and contribute to the immune responses, (3) the pathogenesis of the inflammatory bowel disease, and (4) the therapeutic use of vagus nerve stimulation, and in particular, the transcutaneous stimulation of the auricular branch of the vagus nerve. Then, we expose the working hypotheses for the modulation of the molecular processes that are responsible for intestinal inflammation in autoimmune diseases and the way we could develop personalized neuroprosthetic therapeutic devices and procedures in favor of the patients.

Recognizing the role of the vagus nerve in depression from microbiota-gut brain axis

Depression is a worldwide disease causing severe disability, morbidity, and mortality. Despite abundant studies, the precise mechanisms underlying the pathophysiology of depression remain elusive. Recently, cumulate research suggests that a disturbance of microbiota-gut-brain axis may play a vital role in the etiology of depression while correcting this disturbance could alleviate depression symptoms. The vagus nerve, linking brain and gut through its afferent and efferent branches, is a critical route in the bidirectional communication of this axis. Directly or indirectly, the vagus afferent fibers can sense and relay gut microbiota signals to the brain and induce brain disorders including depression. Also, brain changes in response to stress may result in gut hyperpermeability and inflammation mediating by the vagal efferents, which may be detrimental to depression. Notably, vagus nerve stimulation owns an anti-inflammatory effect and was proved for depression treatment. Nevertheless, depression was accompanied by a low vagal tone, which may derive from response to stress and contribute to pathogenesis of depression. In this review, we aim to explore the role of the vagus nerve in depression from the perspective of the microbiota-gut-brain axis, highlighting the relationship among the vagal tone, the gut hyperpermeability, inflammation, and depression.

Flaxseed Bioactive Compounds: Chemical Composition, Functional Properties, Food Applications and Health Benefits-Related Gut Microbes

Flaxseed (Linum usitatissimum L.) has gained worldwide recognition as a health food because of its abundance in diverse nutrients and bioactive compounds such as oil, fatty acids, proteins, peptides, fiber, lignans, carbohydrates, mucilage, and micronutrients. These constituents attribute a multitude of beneficial properties to flaxseed that makes its use possible in various applications, such as nutraceuticals, food products, cosmetics, and biomaterials. The importance of these flaxseed components has also increased in modern times because of the newer trend among consumers of greater reliance on a plant-based diet for fulfilling their nutritional requirements, which is perceived to be hypoallergenic, more environmentally friendly, sustainable, and humane. The role of flaxseed substances in the maintenance of a healthy composition of the gut microbiome, prevention, and management of multiple diseases has recently been elucidated in various studies, which have highlighted its importance further as a powerful nutritional remedy. Many articles previously reported the nutritive and health benefits of flaxseed, but no review paper has been published reporting the use of individual flaxseed components in a manner to improve the techno-functional properties of foods. This review summarizes almost all possible applications of flaxseed ingredients in food products from an extensive online literature survey; moreover, it also outlines the way forward to make this utilization even better.

A randomized clinical trial to stimulate the cholinergic anti-inflammatory pathway in patients with moderate COVID-19-pneumonia using a slow-paced breathing technique

Purpose

A characteristic problem occurring in COVID-19 is excessive elevations of pro-inflammatory cytokines (e.g. IL-6 and CRP) which are associated with worse clinical outcomes. Stimulation of the vagally-mediated cholinergic anti-inflammatory reflex by slow paced breathing with prolonged exhalation may present a clinically relevant way to reduce circulating IL-6.

Method

Single-center randomized controlled clinical trial with enrolment of 46 patients hospitalized with confirmed severe acute respiratory syndrome Coronavirus 2 (SARS-CoV-2) infection and moderate COVID-19 pneumonia (primary diagnosis). Differences between intervention (4sec inhalation, 6sec exhalation for 20 minutes 3x daily) and control group in IL-6 calculated using multilevel mixed-effect linear regression models with random slope including the covariates relevant comorbidities, COVID-19 medication, and age. Both groups received standard care.

Results

Mean age was 57 years ± 13 years, N= 28 (60%) male, N=30 (65%) with relevant comorbidities. The model including group-by-time interaction revealed a significantly lower trajectory of IL-6 in the intervention group (effect size Cohens f² = 0.11, LR-test p=.040) in the intention-to-treat sample, confirmed by per-protocol analysis (f² = 0.15, LR-test p=.022). Exploratory analysis using the median split of practice time to predict IL-6 of the next morning indicated a dose-response relationship with beneficial effects of practice time above 45 minutes per day. Oxygen saturation remained unchanged during slow-paced breathing (95.1% ± 2.1% to 95.4% ± 1.6%).

Conclusion

Patients practicing slow-paced breathing had significantly lower IL-6 values than controls with a small to medium effect size and without relevant side effects. Further trials should evaluate clinical outcomes and an earlier start of the intervention. Slow-paced breathing could be an easy to implement, low-cost, safe and feasible adjuvant therapeutic approach to reduce circulating IL-6 in moderate COVID-19 pneumonia.

Clinical Trial Registration

https://www.drks.de, identifier DRKS00023971, Universal Trial Number (UTN) U1111-1263-8658.

Electrical neuromodulation therapy for inflammatory bowel disease

Inflammatory bowel disease (IBD) is an inflammatory disease of the gastrointestinal (GI) tract. It has financial and quality of life impact on patients. Although there has been a significant advancement in treatments, a considerable number of patients do not respond to it or have severe side effects. Therapeutic approaches such as electrical neuromodulation are being investigated to provide alternate options. Although bioelectric neuromodulation technology has evolved significantly in the last decade, sacral nerve stimulation (SNS) for fecal incontinence remains the only neuromodulation protocol commonly utilized use for GI disease. For IBD treatment, several electrical neuromodulation techniques have been studied, such as vagus NS, SNS, and tibial NS. Several animal and clinical experiments were conducted to study the effectiveness, with encouraging results. The precise underlying mechanisms of action for electrical neuromodulation are unclear, but this modality appears to be promising. Randomized control trials are required to investigate the efficacy of intrinsic processes. In this review, we will discuss the electrical modulation therapy for the IBD and the data pertaining to it.

Functional anatomy of the vagus system: How does the polyvagal theory comply?

Due to its pivotal role in autonomic networks and interoception, the vagus attracts continued interest from both basic scientists and therapists of various clinical disciplines. In particular, the widespread use of heart rate variability as an index of autonomic cardiac control and a proposed central role of the vagus in biopsychological concepts, e.g., the polyvagal theory, provide a good opportunity to recall basic features of vagal anatomy. In addition to the "classical" vagal brainstem nuclei, i.e., dorsal motor nucleus, nucleus ambiguus and nucleus tractus solitarii, the spinal trigeminal and paratrigeminal nuclei come into play as targets of vagal afferents. On the other hand, the nucleus of the solitary tract receives and integrates not only visceral but also somatic afferents.

Protective effect of α7 nicotinic acetylcholine receptor activation on experimental colitis and its mechanism

Background

Inflammatory bowel disease (IBD) is a common chronic remitting disease with no satisfactory treatment. The aim of this study was to investigate the protective effect of α7 nicotinic acetylcholine receptor (α7nAChR), and to determine the underlying mechanism of its activity.

Methods

The expression and distribution of α7nAChR in the intestinal tissue of patients with ulcerative colitis and Crohn’s disease were analyzed. The effects of vagal excitation on murine experimental colitis were investigated. The colitis model was induced in C57BL/6 mice by the administration of 3% dextran sulfate sodium (DSS). The therapeutic group received treatment with the α7nAChR agonist PNU-282987 by intraperitoneal injection.

Results

Our results showed that there was significantly increased expression of α7nAChR in colitis and Crohn’s disease intestinal tissue, and its expression was mainly located in macrophages and neutrophils, which were extensively infiltrated in the disease status. Treatment with an α7nAChR agonist potently ameliorated the DSS-induced illness state, including weight loss, stool consistency, bleeding, colon shortening, and colon histological injury. α7nAChR agonist exerted anti-inflammatory effects in DSS colitis mice by suppressing the secretion of multiple types of proinflammatory factors, such as IL6, TNFα, and IL1β, and it also inhibited the colonic infiltration of inflammatory cells by blocking the DSS-induced overactivation of the NF-κB and MAPK signaling pathways. Mechanistically, activation of α7nAChR decreased the number of infiltrated M1 macrophages in the colitis intestine and inhibited the phagocytosis ability of macrophages, which were activated in response to LPS stimulation.

Conclusion

Thus, an α7nAChR agonist ameliorated colonic pathology and inflammation in DSS-induced colitis mice by blocking the activation of inflammatory M1 macrophages.

Impact of Non-Pharmacological Interventions on the Mechanisms of Atherosclerosis

Atherosclerosis remains the leading cause of mortality and morbidity worldwide characterized by the deposition of lipids and fibrous elements in the form of atheroma plaques in vascular areas which are hemodynamically overloaded. The global burden of atherosclerotic cardiovascular disease is steadily increasing and is considered the largest known non-infectious pandemic. The management of atherosclerotic cardiovascular disease is increasing the cost of health care worldwide, which is a concern for researchers and physicians and has caused them to strive to find effective long-term strategies to improve the efficiency of treatments by managing conventional risk factors. Primary prevention of atherosclerotic cardiovascular disease is the preferred method to reduce cardiovascular risk. Fasting, a Mediterranean diet, and caloric restriction can be considered useful clinical tools. The protective impact of physical exercise over the cardiovascular system has been studied in recent years with the intention of explaining the mechanisms involved; the increase in heat shock proteins, antioxidant enzymes and regulators of cardiac myocyte proliferation concentration seem to be the molecular and biochemical shifts that are involved. Developing new therapeutic strategies such as vagus nerve stimulation, either to prevent or slow the disease’s onset and progression, will surely have a profound effect on the lives of millions of people.

HFAC Dose Repetition and Accumulation Leads to Progressively Longer Block Carryover Effect in Rat Sciatic Nerve

This paper describes high-frequency nerve block experiments carried out on rat sciatic nerves to measure the speed of recovery of A fibres from block carryover. Block carryover is the process by which nerve excitability remains suppressed temporarily after High Frequency Alternative (HFAC) block is turned off following its application. In this series of experiments 5 rat sciatic nerves were extracted and prepared for ex-vivo stimulation and recording in a specially designed perfusion chamber. For each nerve repeated HFAC block and concurrent stimulation trials were carried out to observe block carryover after signal shutoff. The nerve was allowed to recover fully between each trial. Time to recovery from block was measured by monitoring for when relative nerve activity returned to within 90% of baseline levels measured at the start of each trial. HFAC block carryover duration was found to be dependent on accumulated dose by statistical test for two different HFAC durations. The carryover property of HFAC block on A fibres could enable selective stimulation of autonomic nerve fibres such as C fibres for the duration of carryover. Block carryover is particularly relevant to potential chronic clinical applications of block as it reduces power requirements for stimulation to provide the blocking effect. This work characterizes this process toward the creation of a model describing its behavior.

Ultrasound Neuromodulation of the Spleen Has Time-Dependent Anti-Inflammatory Effect in a Pneumonia Model

Interfaces between the nervous and immune systems have been shown essential for the coordination and regulation of immune responses. Non-invasive ultrasound stimulation targeted to the spleen has recently been shown capable of activating one such interface, the splenic cholinergic anti-inflammatory pathway (CAP). Over the past decade, CAP and other neuroimmune pathways have been activated using implanted nerve stimulators and tested to prevent cytokine release and inflammation. However, CAP studies have typically been performed in models of severe, systemic (e.g., endotoxemia) or chronic inflammation (e.g., collagen-induced arthritis or DSS-induced colitis). Herein, we examined the effects of activation of the splenic CAP with ultrasound in a model of local bacterial infection by lung instillation of 10⁵ CFU of Streptococcus pneumoniae. We demonstrate a time-dependent effect of CAP activation on the cytokine response assay during infection progression. CAP activation-induced cytokine suppression is absent at intermediate times post-infection (16 hours following inoculation), but present during the early (4 hours) and later phases (48 hours). These results indicate that cytokine inhibition associated with splenic CAP activation is not observed at all timepoints following bacterial infection and highlights the importance of further studying neuroimmune interfaces within the context of different immune system and inflammatory states.

PARK7/DJ-1 as a Therapeutic Target in Gut-Brain Axis Diseases

It is increasingly known that Parkinson's (PD) and Alzheimer's (AD) diseases occur more frequently in patients with inflammatory gastrointestinal diseases including inflammatory bowel (IBD) or celiac disease, indicating a pathological link between them. Although epidemiological observations suggest the existence of the gut-brain axis (GBA) involving systemic inflammatory and neural pathways, little is known about the exact molecular mechanisms. Parkinson's disease 7 (PARK7/DJ-1) is a multifunctional protein whose protective role has been widely demonstrated in neurodegenerative diseases, including PD, AD, or ischemic stroke. Recent studies also revealed the importance of PARK7/DJ-1 in the maintenance of the gut microbiome and also in the regulation of intestinal inflammation. All these findings suggest that PARK7/DJ-1 may be a link and also a potential therapeutic target in gut and brain diseases. In this review, therefore, we discuss our current knowledge about PARK7/DJ-1 in the context of GBA diseases.

Vagus nerve stimulation for conservative therapy-refractive epilepsy and depression

Numerous studies confirm that the vagus nerve stimulation (VNS) is an efficient, indirect neuromodulatory therapy with electrically induced current for epilepsy that cannot be treated by epilepsy surgery and is therapy-refractory and for drug therapy-refractory depression. VNS is an established, evidence-based and in the long-term cost-effective therapy in an interdisciplinary overall concept.Long-term data on the safety and tolerance of the method are available despite the heterogeneity of the patient populations. Stimulation-related side effects like hoarseness, paresthesia, cough or dyspnea depend on the stimulation strength and often decrease with continuing therapy duration in the following years. Stimulation-related side effects of VNS can be well influenced by modifying the stimulation parameters. Overall, the invasive vagus nerve stimulation may be considered as a safe and well-tolerated therapy option.For invasive and transcutaneous vagus nerve stimulation, antiepileptic and antidepressant as well as positive cognitive effects could be proven. In contrast to drugs, VNS has no negative effect on cognition. In many cases, an improvement of the quality of life is possible.iVNS therapy has a low probability of complete seizure-freedom in cases of focal and genetically generalized epilepsy. It must be considered as palliative therapy, which means that it does not lead to healing and requires the continuation of specific medication. The functional principle is a general reduction of the neuronal excitability. This effect is achieved by a slow increase of the effectiveness sometimes over several years. Responders are those patients who experience a 50% reduction of the seizure incidence. Some studies even reveal seizure-freedom in 20% of the cases. Currently, it is not possible to differentiate between potential responders and non-responders before therapy/implantation.The current technical developments of the iVNS generators of the new generation like closed-loop system (cardiac-based seizure detection, CBSD) reduce also the risk for SUDEP (sudden unexpected death in epilepsy patients), a very rare, lethal complication of epilepsies, beside the seizure severity.iVNS may deteriorate an existing sleep apnea syndrome and therefore requires possible therapy interruption during nighttime (day-night programming or magnet use) beside the close cooperation with sleep physicians.The evaluation of the numerous iVNS trials of the past two decades showed multiple positive effects on other immunological, cardiological, and gastroenterological diseases so that additional therapy indications may be expected depending on future study results. Currently, the vagus nerve stimulation is in the focus of research in the disciplines of psychology, immunology, cardiology as well as pain and plasticity research with the desired potential of future medical application.Beside invasive vagus nerve stimulation with implantation of an IPG and an electrode, also devices for transdermal and thus non-invasive vagus nerve stimulation have been developed during the last years. According to the data that are currently available, they are less effective with regard to the reduction of the seizure severity and duration in cases of therapy-refractory epilepsy and slightly less effective regarding the improvement of depression symptoms. In this context, studies are missing that confirm high evidence of effectiveness. The same is true for the other indications that have been mentioned like tinnitus, cephalgia, gastrointestinal complaints etc. Another disadvantage of transcutaneous vagus nerve stimulation is that the stimulators have to be applied actively by the patients and are not permanently active, in contrast to implanted iVNS therapy systems. So they are only intermittently active; furthermore, the therapy adherence is uncertain.

Is it time to include older adults in inflammatory bowel disease trials? A call for action

The therapeutic management of older patients with inflammatory bowel disease (IBD) is challenging, particularly because of the absence of evidence-based guidelines for these patients, who seem to frequently be excluded from clinical trials. In this systematic review we investigated the exclusion of older patients with IBD from phase 3 studies registered on PubMed and ClinicalTrials.gov, by assessing the upper limit of age exclusion criteria and the percentage of patients older than 65 years included in the trials. Exclusion criteria other than age were also recorded, and comorbidities were analysed separately. Our review of 222 phase 3 studies shows that older patients are frequently excluded from IBD clinical trials because of their age, which was used as an exclusion criterion in 129 (58%) of the 222 assessed trials. Of the 32 trials that detailed the percentage of included patients who were 65 years or older, only 763 (5·4%) patients of the 14 124 patients included were older than 65 years. In addition to age, patients were also excluded because of comorbidities (mainly renal, hepatic, and cardiovascular, and used as an exclusion criterion in 76% of trials), a history of dysplasia (45% of trials), and previous treatment for IBD (19% of trials). We propose a three-step process that should enable the inclusion of all older patients in IBD clinical trials, regardless of their age, comorbidities, and frailty.

Cholinergic immunomodulation in inflammatory bowel diseases

Inflammatory bowel diseases (IBD) are chronic intestinal disorders characterized by dysregulated immune responses to resident microbiota in genetically susceptible hosts. The activation of the cholinergic system has been proposed for the treatment of IBD patients according to its potential anti-inflammatory effect in vivo. The α-7-nicotinic-acetylcholine receptor (α7nAChR) is involved in the inhibition of inflammatory processes, modulating the production of cytokines, suppressing dendritic cells and macrophage activity, leading to the suppression of T cells. In this review, we address the most recent studies and clinical trials concerning cholinergic signaling and its therapeutic potential for inflammatory bowel diseases.

A potential treatment approach for subclinical mastitis in dairy cows: auriculotherapy of the auricular branch of the vagus nerve

This research aims to test the hypothesis that neural therapy (NT) on the auricular branch of the vagus nerve (ABVN) in dairy cows diagnosed with subclinical mastitis (SCM) results in a reduction of the somatic cell count. Therapeutic options for SCM are mostly based on use of antibiotics and often lead to unsatisfactory results. An alternative therapy targeting the anti-inflammatory properties of the vagus nerve showing good efficacy, economic viability and without major side effects would be of considerable interest. Auriculotherapy (AT) was performed using three repeated infiltrations of 8.0 mg (0.4 ml) procaine hydrochloride (2%) at the location of the ear tag associated with the auricular acupuncture point (AAP) of the udder. Some 85 clinically healthy cows from nine dairy farms were sampled for evaluation of quarter somatic cell count (QSCC) on four days (d0, d2, d4 and d6). Quarters with a QSCC > 100 000 cells/ml on d0 were included in the analysis. Over the study period, a total of 784 quarters were analysed, 385 control (CON) quarters from 40 cows and 399 treated (TRE) quarters from 45 cows. Results showed that AT of the ABNV resulted in a significant reduction of the QSCC after three treatments. The effect was independent of bacteriological culture results of the quarter milk samples. The bacteriological cure rate, however, was not influenced by AT. To our knowledge this is the first report of AT reducing QSCC in dairy cows with SCM. Before AT can be regarded as an alternative therapeutic approach, further research should focus on possible long-term effects of AT on the reduction of SCC, any bacterial elimination and the neural pathways of AT in dairy cows with SCM.

Norwegian population-based study of long-term effects, safety, and predictors of response of vagus nerve stimulation treatment in drug-resistant epilepsy: The NORPulse study

OBJECTIVE

This study was undertaken to evaluate the efficacy of vagus nerve stimulation (VNS) over time, and to determine which patient groups derive the most benefit.

METHODS

Long-term outcomes are reported in 436 epilepsy patients from a VNS quality registry (52.8% adults, 47.2% children), with a median follow-up of 75 months. Patients were stratified according to evolution of response into constant responders, fluctuating responders, and nonresponders. The effect was evaluated at 6, 12, 24, 36, and 60 months. Multivariate regression analysis was used to identify predictors of response.

RESULTS

The cumulative probability of ≥50% seizure reduction was 60%; however, 15% of patients showed a fluctuating course. Of those becoming responders, 89.5% (230/257) did so within 2 years. A steady increase in effect was observed among constant responders, with 48.7% (19/39) of those becoming seizure-free and 29.3% (39/133) with ≥75% seizure reduction achieving these effects within 2-5 years. Some effect (25%-<50%) at 6 months was a positive predictor of becoming a responder (odds ratio [OR] = 10.18, p < .0001) and having ≥75% reduction at 2 years (OR = 3.34, p = .03). Patients without intellectual disability had ORs of 3.34 and 3.11 of having ≥75% reduction at 2 and 5 years, respectively, and an OR of 6.22 of being seizure-free at last observation. Patients with unchanged antiseizure medication over the observation period showed better responder rates at 2 (63.0% vs. 43.1%, p = .002) and 5 years (63.4% vs. 46.3%, p = .031) than patients whose antiseizure medication was modified. Responder rates were higher for posttraumatic (70.6%, p = .048) and poststroke epilepsies (75.0%, p = .05) than other etiologies (46.5%).

SIGNIFICANCE

Our data indicate that the effect of VNS increases over time and that there are important clinical decision points at 6 and 24 months for evaluating and adjusting the treatment. There should be better selection of candidates, as certain patient groups and epilepsy etiologies respond more favorably.