The Effects of Noninvasive Vagus Nerve Stimulation on Fatigue and Immune Responses in Patients With Primary Sjögren's Syndrome

Autonomic neuropathy is associated with an increase in type-1 cytokines in people living with HIV

PURPOSE

Pre-clinical studies have demonstrated direct influences of the autonomic nervous system (ANS) on the immune system. However, it remains unclear if ANS-immune connections delineated in these preclinical studies underlie the relationship between autonomic dysregulation and chronic inflammatory diseases in patients with human immunodeficiency virus (HIV). The aims of this study were: (1) to examine the relationship between interleukin-6 (IL-6) and the parasympathetic/vagal component of baroreflex sensitivity in people with HIV; (2) to determine whether the subtype and severity of HIV-autonomic neuropathy (AN) would predict distinct immunotypes; and (3) to compare the burden of non-acquired immunodeficiency syndrome (AIDS)-related co-morbidities between immunotypes.

METHODS

A total of 79 adults with well-controlled HIV underwent a standard battery of autonomic function tests summarized as the Composite Autonomic Severity Score (CASS) and vagal and adrenergic baroreflex sensitivity (BRS-V and BRS-A, respectively) (Low: Mayo Clin Proc 68:748-752, 1993). Levels of immune biomarkers were measured in all participants using the Target 96 Inflammation Panel on the Olink proteomics platform, and immunotypes were identified using unbiased, non-negative matrix factorization. Mass cytometry (CyTOF) was completed on a subset of participants with and without autonomic neuropathy (N = 10).

RESULTS

Reduced BRS-V predicted higher levels of IL-6 (p = 0.002). A pro-inflammatory immunotype defined by elevations in type 1 cytokines (IL-6, IL-17) and increased numbers of CD8+ T-cells was associated with autonomic neuropathy characterized by deficits in sympathetic nervous system activity (adjusted odds ratio 4.7, p = 0.017). This pro-inflammatory immunotype was older with a greater burden of co-morbidities.

CONCLUSION

Deficits in the parasympathetic/cardiovagal and the sympathetic nervous system are associated with inflammation and disease burden in people living with HIV. Future longitudinal research is needed to examine causality.

COVIVA: Effect of transcutaneous auricular vagal nerve stimulation on fatigue-syndrome in patients with Long Covid - A placebo-controlled pilot study protocol

BACKGROUND

Up to 80% of patients who develop coronavirus disease-2019 (Covid-19) infection subsequently experience long covid/post-covid syndrome. The World Health Organization (WHO) has estimated that >770 million patients have been infected with Covid-19 globally. Even if only 10% of these patients develop long covid, > 75 million patients will suffer for a long period. Among the various symptoms of post-covid syndrome, fatigue is common, affecting up to 60% of the patients. As observed in other viral infections, elevated levels of inflammatory cytokines may play a role. Transcutaneous auricular vagal nerve stimulation (taVNS) is a noninvasive method that modulates the immune system via the central nervous system and has shown promising effects in autoimmune diseases and improving fatigue. In this pilot study, we investigated the feasibility of daily taVNS in patients with long covid-related fatigue. Additionally, the effects of taVNS on fatigue and quality of life will be analyzed.

METHODS

A total of 45 adult patients with long covid associated fatigue syndrome will be enrolled in this study, and will be randomized to the above-threshold-stimulation, below-threshold-stimulation, or sham-stimulation arms, after being informed that they will feel the stimulation. The above-threshold-group will receive a 4-week-long left-sided cymba conchae taVNS with 25 Hz, 250 µs pulse width 28s/32s on/off paradigm for 4 h throughout the day. The below-threshold group will receive stimulation below the sensational threshold, whereas the sham group will receive no stimulation following application of a non-functional electrode. The daily stimulation protocol will be recorded either manually or using the provided app. Three well-established questionnaires, the Multidimensional-Fatigue-Inventory-20, Short-Form-36, and Beck-Depression-Inventory, and the newly established Post-Covid-Syndrome-Score will be completed both before and after 4 weeks of stimulation.

DISCUSSION

The primary endpoint has been set as the patients' average daily stimulation time after 4 weeks, while secondary endpoints include the effects of taVNS on fatigue and Quality of Live (QoL). As a non-invasive treatment option, taVNS may be a notable alternative for patients with post-covid related fatigue.

TRIAL REGISTRATION

This study was approved by the local ethics committee (23/7798) and registered (DRKS00031974) (see supporting information files).

ETHICS & DISSEMINATION

The ethical justifiability of this study was supported by prior research demonstrating the safety of taVNS. Patients will be recruited by general practitioners, and written informed consent will be obtained. All data will be pseudonymized for collection and storage. The study results will be published in peer-reviewed journals with the aim of providing evidence of the potential of taVNS in long covid management. The study will be conducted in accordance with the principles of the Declaration of Helsinki.

British Society for Rheumatology guideline on management of adult and juvenile onset Sjögren disease

Sjögren disease (SD) is a chronic, autoimmune disease of unknown aetiology with significant impact on quality of life. Although dryness (sicca) of the eyes and mouth are the classically described features, dryness of other mucosal surfaces and systemic manifestations are common. The key management aim should be to empower the individual to manage their condition-conserving, replacing and stimulating secretions; and preventing damage and suppressing systemic disease activity. This guideline builds on and widens the recommendations developed for the first guideline published in 2017. We have included advice on the management of children and adolescents where appropriate to provide a comprehensive guideline for UK-based rheumatology teams.

Effect of transcutaneous vagus nerve stimulation in hemodialysis patients: A randomized controlled trial

INTRODUCTION

Transcutaneous auricular vagus nerve stimulation (tVNS) has shown potential in neurological, autoimmune, and cardiovascular disorders, but its effects on HD patients remain unclear. This study aimed to evaluate the efficacy and safety of tVNS in HD patients.

METHODS

We conducted a randomized controlled clinical trial on patients receiving HD ≥6 months. The tVNS group received stimulation for 1 h during the first 2 h of HD sessions, three times weekly for 8 weeks, while the control group received standard care. The primary outcomes were dialysis efficiency (Single-pool Kt/V, Sp Kt/V) and dialysis-related symptoms (Dialysis Symptom Index, DSI), assessed every 4 weeks. Secondary outcomes included pain and fatigue scores, physical performance, Hemodialysis Comfort Scale, hemoglobin levels, Mini-Mental State Examination, and anxiety and depression scores, measured at baseline and 8 weeks after intervention.

RESULTS

A total of 63 patients were enrolled in the study, with 32 patients assigned to the tVNS group and 31 patients to the control group. At 8 weeks, the tVNS group showed significant improvements in Sp Kt/V (1.31 ± 0.11 vs. 1.25 ± 0.10, p = 0.02), and DSI (12.09 ± 5.84 vs. 16.26 ± 5.27, p = 0.004), as well as reductions in pain and fatigue, and increases in physical function, comfort, and hemoglobin. However, there were no statistically significant changes observed in cognitive function, anxiety, or depression.

CONCLUSIONS

tVNS could improve dialysis efficiency, symptoms, and physical function in HD patients, indicating it may have a role as a complementary therapy.

The Autonomic Nervous System (ANS)-Immune Network in People Living With HIV

Purpose

Pre-clinical studies have demonstrated direct influences of the autonomic nervous system (ANS) on the immune system. However, it remains unknown if connections between the peripheral ANS and immune system exist in humans and contribute to the development of chronic inflammatory disease. This study had three aims: 1.) To examine the relationship between IL-6 and the parasympathetic/vagal component of baroreflex sensitivity (BRS-V) in people with HIV; 2.) To determine if the subtype and severity of HIV-autonomic neuropathy (AN) would predict distinct immunotypes; 3.) To compare the burden of non-AIDS-related co-morbidities between immunotypes.

Methods

79 adult people with well-controlled HIV underwent a standard battery of autonomic function tests summarized as the Composite Autonomic Severity Score and vagal and adrenergic baroreflex sensitivity (BRS-V and BRS-A). Levels of immune biomarkers were measured in all participants using the Target 96 Inflammation Panel on the Olink proteomics platform and immunotypes were identified using unbiased, non-negative matrix factorization. Mass cytometry (CyTOF) was completed on a subset of participants with and without autonomic neuropathy (N = 10).

Results

First, we found reduced BRS-V predicted higher levels of IL-6 (p = 0.002). Second, a pro-inflammatory immunotype defined by elevations in type 1 cytokines (IL-6, IL-17) and increased numbers of CD8 + T-cells was associated with autonomic neuropathy characterized by deficits in sympathetic nervous system activity (aOR = 4.7, p = 0.017). This pro-inflammatory immunotype was older with a greater burden of co-morbidities.

Conclusion

Deficits in the parasympathetic/cardiovagal and the sympathetic nervous system are associated with inflammation and disease burden in people living with HIV. Future longitudinal research is needed to examine causality.

Autonomic and Immune Stress Response Networks in Patients Living With HIV

Background and Objectives

Stress response systems are frequently dysregulated in patients with chronic inflammatory disorders. Pre-clinical studies have demonstrated direct influences of the sympathetic and vagal/parasympathetic branches of the autonomic nervous system (ANS) on the immune system. However, these connections have not been examined in humans. We hypothesized that the subtype and severity of autonomic neuropathy (AN) would predict immune phenotypes with distinct clinical and demographic characteristics in people living with HIV.

Methods

This is a cross-sectional study of 79 adult people with a history of well-controlled HIV on stable combination antiretroviral treatment (CART) recruited from a primary care clinic network within the Mount Sinai Health System in New York City. All participants underwent a standardized battery of autonomic function tests summarized as the Composite Autonomic Severity Score (CASS) and vagal and adrenergic baroreflex sensitivity (BRS-V and BRS-A). Immune profiling included: 1) measurement of interleukin-6 (IL-6) as part of the Olink assay Target 96 Inflammation Panel, 2) non-negative matrix factorization (NMF) clustering analyses on Olink immune biomarkers, and 3) mass cytometry (CyTOF) on a subset of participants with and without autonomic neuropathy (N = 10).

Results

Reduced activity of caudal vagal circuitry involved in the cholinergic anti-inflammatory pathway (CAP) predicted higher levels of IL-6 (Spearman's rho = -0.352, p=0.002). The comprehensive assessment of the ANS-immune network showed four immunotypes defined by NMF analyses. A pro-inflammatory immunotype defined by elevations in type 1 cytokines (IL-6, IL-17) and increased numbers of CD8+ T-cells was associated with autonomic neuropathy (AN). This association was driven by deficits in the cardiovascular sympathetic nervous system and remained strongly significant after controlling for the older age and greater burden of co-morbid illness among participants with this immunotype (aOR=4.7, p=0.017).

Discussion

Our results provide novel support for the clinical relevance of the CAP in patients with chronic inflammatory AN. These data also provide insight regarding the role of the sympathetic nervous system and aging in the progression and development of co-morbidities in patients with chronic HIV and support future research aimed at developing therapies focused on modulation of the sympathetic and parasympathetic/vagal nervous system.

Improved Fatigue Management in Primary Sjögren's Syndrome: A Retrospective Analysis of the Efficacy of Methotrexate in Chinese Patients

Objective

To assess the efficacy of methotrexate (MTX) and hydroxychloroquine (HCQ) in improving fatigue symptoms in patients with primary Sjögren's syndrome (pSS).

Methods

A single-center retrospective study was conducted on pSS patients experiencing fatigue symptoms. All patients received either MTX, HCQ, or a combination of MTX + HCQ for a period of six months. Clinical efficacy was measured using the European League Against Rheumatism (EULAR) Sjögren's Syndrome Disease Activity Index (ESSDAI), EULAR Sjögren's Syndrome Patient Reported Index (ESSPRI), Functional Assessment of Chronic Illness Therapy-Fatigue (FACIT-F), fatigue severity scale (FSS), and visual analog scale (VAS) score. These measures were assessed at baseline and at 1, 2, 3, and 6 months.

Results

A total of 86 pSS patients with fatigue symptoms were enrolled (27 received MTX, 29 received HCQ, and 30 received MTX + HCQ). Patients receiving MTX and MTX + HCQ showed significant improvements at 6th month in ESSDAI, ESSPRI, FSS, FACIT-F, and VAS scores (all P < 0.01) compared with baseline. Repeated-measures analysis of variance revealed that patients treated with MTX and MTX + HCQ experienced significant improvements in ESSDAI, FSS, FACIT-F, and VAS scores (all P < 0.01) from baseline to the 6th month. The HCQ group did not show significant improvement in FSS, FACIT-F, and VAS scores (all P > 0.05), although their ESSDAI and ESSPRI scores did improve significantly (all P < 0.01). Patients in the MTX group showed the most improvement in mean changes of ESSDAI score, FSS score, FACIT-F score, and VAS score from baseline to the 6th month. And patients received MTX treatment significantly had more fatigue remission numbers (all P < 0.05).

Conclusion

In clinical practice, methotrexate is more effective than hydroxychloroquine in improving fatigue symptoms, as measured by patient-reported fatigue scales (FSS, FACIT-F, and VAS scores) in patients with pSS.

Unraveling the fatigue puzzle: insights into the pathogenesis and management of IBD-related fatigue including the role of the gut-brain axis

A significant percentage of patients with an inflammatory bowel disease (IBD) encounter fatigue which can profoundly diminish patients' quality of life, particularly during periods of disease remission when gastrointestinal symptoms have receded. Various contributing risk factors have been identified including active inflammation, anemia, psychological, lifestyle and drug-related factors. While addressing these risk factors has been suggested as the initial approach to managing fatigue, a considerable number of patients still experience persisting symptoms, the primary causes of which remain incompletely understood. Recent insights suggest that dysfunction of the gut-brain axis may play a pathogenic role. This review provides an overview of established risk factors for fatigue, alongside emerging perspectives on the role of the gut-brain axis, and potential treatment strategies.

The immunomodulatory effect of oral NaHCO3 is mediated by the splenic nerve: multivariate impact revealed by artificial neural networks

Stimulation of the inflammatory reflex (IR) is a promising strategy for treating systemic inflammatory disorders. Recent studies suggest oral sodium bicarbonate (NaHCO3) as a potential activator of the IR, offering a safe and cost-effective treatment approach. However, the mechanisms underlying NaHCO3-induced anti-inflammatory effects remain unclear. We investigated whether oral NaHCO3's immunomodulatory effects are mediated by the splenic nerve. Female rats received NaHCO3 or water (H2O) for four days, and splenic immune markers were assessed using flow cytometry. NaHCO3 led to a significant increase (p < 0.05, and/or partial eta squared > 0.06) in anti-inflammatory markers, including CD11bc + CD206 + (M2-like) macrophages, CD3 + CD4 + FoxP3 + cells (Tregs), and Tregs/M1-like ratio. Conversely, proinflammatory markers, such as CD11bc + CD38 + TNFα + (M1-like) macrophages, M1-like/M2-like ratio, and SSChigh/SSClow ratio of FSChighCD11bc + cells, decreased in the spleen following NaHCO3 administration. These effects were abolished in spleen-denervated rats, suggesting the necessity of the splenic nerve in mediating NaHCO3-induced immunomodulation. Artificial neural networks accurately classified NaHCO3 and H2O treatment in sham rats but failed in spleen-denervated rats, highlighting the splenic nerve's critical role. Additionally, spleen denervation independently influenced Tregs, M2-like macrophages, Tregs/M1-like ratio, and CD11bc + CD38 + cells, indicating distinct effects from both surgery and treatment. Principal component analysis (PCA) further supported the separate effects. Our findings suggest that the splenic nerve transmits oral NaHCO3-induced immunomodulatory changes to the spleen, emphasizing NaHCO3's potential as an IR activator with therapeutic implications for a wide spectrum of systemic inflammatory conditions.

Vagus nerve stimulation: Potential for treating chronic wounds

Vagus nerve stimulation (VNS) has been approved as a treatment for various conditions, including drug-resistant epilepsy, migraines, chronic cluster headaches and treatment-resistant depression. It is known to have anti-inflammatory, anti-nociceptive and anti-adrenergic effects, and its therapeutic potential for diverse pathologies is being investigated. VNS can be achieved through invasive (iVNS) or non-invasive (niVNS) means, targeting different branches of the vagus nerve. iVNS devices require surgical implantation and have associated risks, while niVNS devices are generally better tolerated and have a better safety profile. Studies have shown that both iVNS and niVNS can reduce inflammation and pain perception in patients with acute and chronic conditions. VNS devices, such as the VNS Therapy System and MicroTransponder Vivistim, have received Food and Drug Administration approval for specific indications. Other niVNS devices, like NEMOS and gammaCore, have shown effectiveness in managing epilepsy, pain and migraines. VNS has also demonstrated potential in autoimmune disorders, such as rheumatoid arthritis and Crohn's disease, as well as neurological disorders like epilepsy and migraines. In addition, VNS has been explored in cardiovascular disorders, including post-operative atrial fibrillation and myocardial ischemia-reperfusion injury, and has shown positive outcomes. The mechanisms behind VNS's effects include the cholinergic anti-inflammatory pathway, modulation of cytokines and activation of specialised pro-resolving mediators. The modulation of inflammation by VNS presents a promising avenue for investigating its potential to improve the healing of chronic wounds. However, more research is needed to understand the specific mechanisms and optimise the use of VNS in wound healing. Ongoing clinical trials may support the use of this modality as an adjunct to improve healing.

Transcutaneous auricular vagus nerve stimulation for the treatment of myoarthropatic symptoms in patients with craniomandibular dysfunction - a protocol for a randomized and controlled pilot trial

BACKGROUND

Temporomandibular disorders (TMD) are a collective term for pain and dysfunction of the masticatory muscles and the temporomandibular joints. The most common types of TMD are pain-related, which may impact the psychological behavior and quality of life. Currently, the most popular methods for the treatment of TMD patients are occlusal splint therapy, often in combination with physical- and/or pharmacotherapy. However, due to the complexity of etiology, the treatment of chronic TMD remains a challenge. Recently, CE-certified systems for non-invasive VNS (transcutaneous auricular vagus nerve stimulation, taVNS) have become available and show positive effects in the treatment of chronic pain conditions, like migraine or fibromyalgia, with which TMD shares similarities. Therefore, it is the main purpose of the study to evaluate the feasibility of daily taVNS against chronic TMD and to assess whether there is an improvement in pain severity, quality of life, and kinetic parameters.

METHODS

This study is designed as a single-blinded, double-arm randomized controlled trial (RCT) in a 1:1 allocation ratio. Twenty adult patients with chronical TMD symptoms will be enrolled and randomized to stimulation or sham group. In the stimulation group, taVNS is performed on the left tragus (25 Hz, pulse width 250 µs, 28 s on/32 s off, 4 h/day). The sham group will receive no stimulation via a non-functional identical-looking electrode. Validated questionnaire data and clinical parameters will be collected at the beginning of the study and after 4 and 8 weeks. The compliance of a daily taVNS of patients with chronical TMD will be evaluated via a smartphone app recording daily stimulation time and average intensity. Additionally, the treatment impact on pain severity and quality of life will be assessed with different questionnaires, and the effect on the mandibular mobility and muscle activity will be analyzed.

DISCUSSION

This is the first clinical trial to assess the feasibility of taVNS in patients with chronic TMD symptoms. If taVNS improves the symptoms of TMD, it will be a significant gain in quality of life for these chronic pain patients. The results of this pilot study will help to determine the feasibility of a large-scale RCT.

TRIAL REGISTRATION

This study has been registered in the DRKS database (DRKS00029724).

Stimulation of the vagus nerve as a therapeutic principle

Modulation of the parasympathetic tone leads to extensive physiological reactions at several levels, including the decreased production of proinflammatory cytokines. Many studies have demonstrated that chronic inflammatory diseases are associated with reduced parasympathetic and increased sympathetic activities. Moreover, it was demonstrated that a low parasympathetic and a high sympathetic activity in patients with rheumatoid arthritis (RA) predicts a poor therapeutic response to anti-tumor necrosis factor (TNF) treatment compared to RA patients with a more balanced autonomic nervous system. The autonomic equilibrium could be restored by electrical stimulation of the vagus nerve. Considering the patients who do not sufficiently respond to the available drugs, patients for whom the effectiveness of the drugs wanes over time, or have drug-related adverse events, a nonpharmacological approach such as bioelectronics might be a useful supplement as an instrument in the successful extension of the therapeutic armamentarium for rheumatic diseases; however, there is a great need for further studies and the development of novel therapeutic strategies in the field of neuroimmunology.

No consistent evidence for the anti-inflammatory effect of vagus nerve stimulation in humans: A systematic review and meta-analysis

Vagus nerve stimulation (VNS) has been identified as an innovative immunosuppressive treatment strategy in rodent studies. However, its' clinical potential is still unclear. Therefore, we aimed to assess whether VNS can reduce inflammatory proteins and/or immune cells in humans, through a pre-registered systematic review and meta-analysis according to PRISMA guidelines. The databases Cochrane, Pubmed and World of Knowledge were searched in duplicate up to the 3rd of March 2022 and publications from identified clinical trial registrations were identified until 20th of August 2023. Studies were included if they provided peer-reviewed data for humans who received VNS as short-term (<=1 day) or long-term (>=2 days-365 days) stimulation and reported at least one cytokine or immune cell after treatment.Screening of title, abstract, full text, and data extraction was performed in duplicate by two independent reviewers. Data were pooled using a random-effects model and meta-regression was performed for moderating factors. Reporting bias was assessed. The standardized mean difference (Hedge's g) was used to indicate overall differences of cytokine data (mean and standard deviation or median and interquartile range at the study level) to test our a-priori hypothesis. The systematic review of 36 studies with 1135 participants (355 receiving a control/sham condition and 780 receiving VNS) revealed anti-inflammatory effects of VNS for cytokines in several reports, albeit often in subgroup analyses, but our meta-analyses of 26 studies did not confirm these findings. Although most cytokines were numerically reduced, the reduction did not reach statistical significance after VNS: not in the between-group comparisons (short-term: TNF-α: g = -0.21, p = 0.359; IL-6: g = -0.94, p = 0.112; long-term: TNF-α: g = -0.13, p = 0.196; IL-6: g = -0.67, p = 0.306); nor in the within-study designs (short-term: TNF-α: g = -0.45, p = 0.630; IL-6: g = 0.28, p = 0.840; TNF-α: g = -0.53, p = 0.297; IL-6:g = -0.02, p = 0.954). Only the subgroup analysis of 4 long-term studies with acute inflammation was significant: VNS decreased CRP significantly more than sham stimulation. Additional subgroup analyses including stimulation duration, stimulation method (invasive/non-invasive), immune stimulation, and study quality did not alter results. However, heterogeneity was high, and most studies had poor to fair quality. Given the low number of studies for each disease, a disease-specific analysis was not possible. In conclusion, while numeric effects were reported in individual studies, the current evidence does not substantiate the claim that VNS impacts inflammatory cytokines in humans. However, it may be beneficial during acute inflammatory events. To assess its full potential, high-quality studies and technological advances are required.

Vagus nerve stimulation as a therapeutic option in inflammatory rheumatic diseases

The vagus nerve forms intricate neural connections with an extensive number of organs, particularly the digestive system. The vagus nerve has a pivotal role as a fundamental component of the autonomic nervous system, exhibiting an essential effect. It establishes a direct link with the parasympathetic system, consequently eliciting the synaptic release of acetylcholine. Recent studies have revealed the potential anti-inflammatory function of the vagus nerve. The activation of the hypothalamic system through the stimulation of vagal afferents is fundamentally involved in regulating inflammation. This activation process leads to the production of cortisol. The other mechanism, defined as the cholinergic anti-inflammatory pathway, is characterized by the involvement of vagal efferents. These fibers release the neurotransmitter acetylcholine at particular synaptic connections, involving interactions with macrophages and enteric neurons. The mechanism under consideration is ascribed to the α-7-nicotinic acetylcholine receptors. The fusion of acetylcholine receptors is responsible for the restricted secretion of inflammatory mediators by macrophages. A potential mechanism for anti-inflammatory effects involves the stimulation of the sympathetic system through the vagus nerve, leading to the control of immunological responses within the spleen. This article offers an extensive summary of the present knowledge regarding the therapeutic effectiveness of stimulating the vagus nerve in managing inflammatory rheumatic conditions based on the relationship of inflammation with the vagus nerve. Furthermore, the objective is to present alternatives that may be preferred while applying vagus nerve stimulation approaches.

The effect of transcutaneous auricular vagus nerve stimulation on cycling ergometry and recovery in healthy young individuals

BACKGROUND

It is aimed to examine the potential benefits and effects of the use of transcutaneous auricular vagus nerve stimulation (VNS) for sporting purposes on recovery, fatigue, and sportive performance level.

METHODS

In this study, 90 people between the ages of 18-23 were participated. They were randomly divided into three groups as bilateral sham, unilateral left, and bilateral VNS. A 4-day protocol was applied to the participants. Cycling exercise was performed with maximum performance for 30 min under the same watt load. Pulse, systolic and diastolic blood pressure, distance, pain, fatigue, lactic acid level, and autonomic nervous system were evaluated.

RESULTS

Within the groups, there was a statistically significant difference between the data (p < .05) except for the distance covered parameter. When we compare the groups, in addition to the distance traveled in all groups, there is no statistically significant difference in the 1st day 1st measurement and 2nd measurement data of all parameters (p > .05 When we compared the data according to days, there was a statistically significant difference between bilateral stimulation (BS) and unilateral stimulation, only pain and fatigue levels (p < .05).

CONCLUSION

In our study, we saw that BS application gave positive results in reducing pain and fatigue due to cycling exercise compared to other applications. Similar results were obtained when we evaluated the data on a daily basis. We believe that VNS will be beneficial in reducing pain and fatigue, especially during and after the competition halftime.

Sleep disorders in Lewy body dementia: Mechanisms, clinical relevance, and unanswered questions

In Lewy body dementia (LBD), disturbances of sleep and/or arousal including insomnia, excessive daytime sleepiness, rapid eye movement (REM) sleep behavior disorder, obstructive sleep apnea, and restless leg syndrome are common. These disorders can each exert a significant negative impact on both patient and caregiver quality of life; however, their etiology is poorly understood. Little guidance is available for assessing and managing sleep disorders in LBD, and they remain under-diagnosed and under-treated. This review aims to (1) describe the specific sleep disorders which occur in LBD, considering their putative or potential mechanisms; (2) describe the history and diagnostic process for these disorders in LBD; and (3) summarize current evidence for their management in LBD and consider some of the ongoing and unanswered questions in this field and future research directions.

Optimizing Noninvasive Vagus Nerve Stimulation for Systemic Lupus Erythematosus: Protocol for a Multicenter Randomized Controlled Trial

BACKGROUND

Systemic lupus erythematosus is a chronic, multisystem, inflammatory disease of autoimmune etiology occurring predominantly in women. A major hurdle to the diagnosis, treatment, and therapeutic advancement of this disease is its heterogeneous nature, which presents as a wide range of symptoms such as fatigue, fever, musculoskeletal involvement, neuropsychiatric disorders, and cardiovascular involvement with varying severity. The current therapeutic approach to this disease includes the administration of immunomodulatory drugs that may produce unfavorable secondary effects.

OBJECTIVE

This study explores the known relationship between the autonomic nervous system and inflammatory pathways to improve patient outcomes by treating autonomic nervous system dysregulation in patients via noninvasive vagus nerve stimulation. In this study, data including biomarkers, physiological signals, patient outcomes, and patient quality of life are being collected and analyzed. After completion of the clinical trial, a computer model will be developed to identify the biomarkers and physiological signals related to lupus activity in order to understand how they change with different noninvasive vagus nerve stimulation frequency parameters. Finally, we propose building a decision support system with integrated noninvasive wearable technologies for continuous cardiovascular and peripheral physiological sensing for adaptive, patient-specific optimization of the noninvasive vagus nerve stimulation frequency parameters in real time.

METHODS

The protocol was designed to evaluate the efficacy and safety of transauricular vagus nerve stimulation in patients with systemic lupus erythematosus. This multicenter, national, randomized, double-blind, parallel-group, placebo-controlled study will recruit a minimum of 18 patients diagnosed with this disease. Evaluation and treatment of patients will be conducted in an outpatient clinic and will include 12 visits. Visit 1 consists of a screening session. Subsequent visits up to visit 6 involve mixing treatment and evaluation sessions. Finally, the remaining visits correspond with early and late posttreatment follow-ups.

RESULTS

On November 2022, data collection was initiated. Of the 10 participants scheduled for their initial appointment, 8 met the inclusion criteria, and 6 successfully completed the entire protocol. Patient enrollment and data collection are currently underway and are expected to be completed in December 2023.

CONCLUSIONS

The results of this study will advance patient-tailored vagus nerve stimulation therapies, providing an adjunctive treatment solution for systemic lupus erythematosus that will foster adoption of technology and, thus, expand the population with systemic lupus erythematosus who can benefit from improved autonomic dysregulation, translating into reduced costs and better quality of life.

TRIAL REGISTRATION

ClinicalTrials.gov NCT05704153; https://clinicaltrials.gov/study/NCT05704153.

INTERNATIONAL REGISTERED REPORT IDENTIFIER (IRRID)

DERR1-10.2196/48387.

Pharmacological and Electroceutical Targeting of the Cholinergic Anti-Inflammatory Pathway in Autoimmune Diseases

Continuous dialogue between the immune system and the brain plays a key homeostatic role in various immune responses to environmental cues. Several functions are under the control of the vagus nerve-based inflammatory reflex, a physiological mechanism through which nerve signals regulate immune functions. In the cholinergic anti-inflammatory pathway, the vagus nerve, its pivotal neurotransmitter acetylcholine, together with the corresponding receptors play a key role in modulating the immune response of mammals. Through communications of peripheral nerves with immune cells, it modulates proliferation and differentiation activities of various immune cell subsets. As a result, this pathway represents a potential target for treating autoimmune diseases characterized by overt inflammation and a decrease in vagal tone. Consistently, converging observations made in both animal models and clinical trials revealed that targeting the cholinergic anti-inflammatory pathway using pharmacologic approaches can provide beneficial effects. In parallel, bioelectronic medicine has recently emerged as an alternative approach to managing systemic inflammation. In several studies, nerve electrostimulation was reported to be clinically relevant in reducing chronic inflammation in autoimmune diseases, including rheumatoid arthritis and diabetes. In the future, these new approaches could represent a major therapeutic strategy for autoimmune and inflammatory diseases.

[Stimulation of the vagus nerve as a therapeutic principle. German Version]

Modulation of the parasympathetic tone leads to extensive physiological reactions at several levels, including the decreased production of proinflammatory cytokines. Many studies have demonstrated that chronic inflammatory diseases are associated with reduced parasympathetic and increased sympathetic activities. Moreover, it was demonstrated that a low parasympathetic and a high sympathetic activity in patients with rheumatoid arthritis (RA) predicts a poor therapeutic response to anti-tumor necrosis factor (TNF) treatment compared to RA patients with a more balanced autonomic nervous system. The autonomic equilibrium could be restored by electrical stimulation of the vagus nerve. Considering the patients who do not sufficiently respond to the available drugs, patients for whom the effectiveness of the drugs wanes over time, or have drug-related adverse events, a nonpharmacological approach such as bioelectronics might be a useful supplement as an instrument in the successful extension of the therapeutic armamentarium for rheumatic diseases; however, there is a great need for further studies and the development of novel therapeutic strategies in the field of neuroimmunology.

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.

Acupoint stimulation for long COVID: A promising intervention:

"Long COVID" is a sustained symptom following infection with severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2). According to recent statistics, at least 65 million people have long COVID, which poses a long-term threat to human health. The pathogenic mechanisms of coronavirus disease 2019 (COVID-19) are complex and affect multiple organs and systems. Common symptoms include palpitations, breathing difficulties, attention and memory deficits, fatigue, anxiety, and depression. It is difficult to achieve satisfactory treatment effect with a single intervention. Currently, treatment strategies for long COVID are still in the exploratory stage, and there is an urgent need to find appropriate and effective methods for long COVID treatment. Traditional Chinese medicine is effective in treating the various phases of COVID-19. Previous studies have shown that acupoint stimulation therapy is effective in improving palpitations, dyspnea, cognitive impairment, anxiety, depression, and other symptoms in patients. According to previous studies, acupoint stimulation may improve various symptoms related to long COVID. This paper discusses the potential application value of acupoint stimulation in the treatment of long COVID-related symptoms, based on the common sequelae of various systems involved in long COVID, and the effect of acupoint stimulation in the treatment of similar symptoms and diseases in recent years.

Depression in Sjögren's syndrome mediates the relationship between pain, fatigue, sleepiness, and overall quality of life

Objectives

Sjögren's syndrome (SS) includes many extra-glandular symptoms such as fatigue, pain, sleepiness and depression, which impact on quality of life (QoL). These symptoms also influence each other and could be linked by autonomic nervous system (ANS) dysregulation. Our aim was to model the role of putative predictive variables, including depression in the relationships between ANS function, fatigue, and QoL in SS.

Methods

Cross-sectional analysis of self-reported data from the multicentre UK primary SS registry. The Composite Autonomic Symptom Scale (COMPASS) was used to assess autonomic function, the Hospital Anxiety and Depression Scale (HADS) to assess anxiety and depression and the EuroQol-5 Dimension (EQ-5D) to assess QoL. Validated scales were used for other clinical variables. Using multiple regression analysis and structural equation modelling (SEM), we investigated how the QoL of people with SS is impacted by the direct and indirect effects of fatigue, sleepiness, depression, symptom burden and ANS function, and their interactions.

Results

Data was obtained for 1046 people with SS, 56% COMPASS completers. Symptoms of ANS dysregulation were common. Participants with ANS dysregulation had more severe depression, anxiety, dryness, fatigue, pain, sleepiness and QoL (P < 0.01 for all). Depression, anxiety, dryness, and pain were independent predictors of ANS function in the multiple regression model (P < 0.05 for all). ANS function could not be included in the SEM. The SEM model had good fit to the data (comparative fit index = 0.998) and showed that, in people with SS, depression mediates the effects of pain, fatigue and sleepiness on QoL.

Conclusion

Our results show that diagnosing and treating depression in people with SS could have direct positive impact on QoL, and significantly ameliorate the impact of fatigue and pain.

Effect of transcutaneous auricular vagal nerve stimulation on the fatigue syndrome in patients with gastrointestinal cancers - FATIVA: a randomized, placebo-controlled pilot study protocol

BACKGROUND

Cancer-related fatigue (CRF) is defined as a "distressing, persistent, subjective sense of physical, emotional, and/or cognitive tiredness or exhaustion related to cancer or cancer treatment that is not proportional to recent activity and interferes with usual functioning." CRF is frequently observed in cancer patients even before the initiation of tumor therapy. Its cause is not clear, but in addition to primary effects of therapy, a tumor-induced elevated level of inflammatory cytokines may play a role. Transcutaneous auricular vagal nerve stimulation (taVNS) is a noninvasive way to activate central nervous pathways and modulate pain perception and the immune system. It has positive effects on autoimmune conditions and can also improve fatigue associated with Sjogren's syndrome. It is the main purpose of this feasibility study to investigate the feasibility of daily taVNS against CRF. Therefore, the stimulation protocol of the newly introduced smartphone app of the manufacturer is evaluated. Additionally, the effect taVNS on CRF and quality of life (QoL) shall be evaluated.

METHODS

Thirty adult patients with gastrointestinal tumors during or after treatment, relevant CRF (Hornheide questionnaire) and life expectancy > 1 year, are enrolled. Patients are randomized to treatment or sham arm and be informed that they will either feel the stimulation or not. Treatment group will receive left-sided tragus above-threshold stimulation with 25 Hz, 250 µs pulse width, and 28-s/32-s on/off paradigm for 4 h throughout the day for 4 weeks. Sham group will receive no stimulation via a nonfunctional electrode. A daily stimulation protocol with time and average intensity is automatically created by a smartphone app connected to the stimulator via Bluetooth®. Multidimensional Fatigue Inventory-20, Short-Form 36 and Beck Depression Inventory questionnaires will be filled out before and after 4 weeks of stimulation.

DISCUSSION

Primarily, the patients' daily stimulation time and intensity will be evaluated through the electronic protocol after 4 weeks. Secondarily, the effect of taVNS on cancer-related fatigue and QoL will be measured through the questionnaires. As taVNS seems to modulate inflammatory cytokines, this noninvasive method may - if accepted by the patients - be a promising adjunct in the treatment of cancer-related fatigue.

TRIAL REGISTRATION

The study was approved by local ethics committee (21-7395) and registered at the DRKS database (DRKS00027481).

Neural dysregulation in post-COVID fatigue

Following infection with SARS-CoV-2, a substantial minority of people develop lingering after-effects known as 'long COVID'. Fatigue is a common complaint with a substantial impact on daily life, but the neural mechanisms behind post-COVID fatigue remain unclear. We recruited 37 volunteers with self-reported fatigue after a mild COVID infection and carried out a battery of behavioural and neurophysiological tests assessing the central, peripheral and autonomic nervous systems. In comparison with age- and sex-matched volunteers without fatigue (n = 52), we show underactivity in specific cortical circuits, dysregulation of autonomic function and myopathic change in skeletal muscle. Cluster analysis revealed no subgroupings, suggesting post-COVID fatigue is a single entity with individual variation, rather than a small number of distinct syndromes. Based on our analysis, we were also able to exclude dysregulation in sensory feedback circuits and descending neuromodulatory control. These abnormalities on objective tests may aid in the development of novel approaches for disease monitoring.

The Effects of Noninvasive Vagus Nerve Stimulation on Fatigue in Participants With Primary Sjögren's Syndrome

OBJECTIVES

Fatigue is one of the most important symptoms needing improvement in Primary Sjögren's syndrome (PSS). Previous data from our group suggest that noninvasive stimulation of the vagus nerve (nVNS) may improve symptoms of fatigue. This experimental medicine study uses the gammaCore device (electroCore) and a sham device to investigate the relationship between nVNS and fatigue in PSS, and to explore potential mechanisms involved.

MATERIALS AND METHODS

Forty participants with PSS were randomly assigned to use active (n = 20) or sham (n = 20) nVNS devices twice daily for 54 days in a double-blind manner. Patient-reported measures of fatigue were collected at baseline and day 56: Profile of Fatigue (PRO-F)-Physical, PRO-F-Mental and Visual Analogue Scale of abnormal fatigue (fVAS). Neurocognitive tests, immunologic responses, electroencephalography alpha reactivity, muscle acidosis, and heart rate variability were compared between devices from baseline to day 56 using analysis of covariance.

RESULTS

PRO-F-Physical, PRO-F-Mental, and fVAS scores were significantly reduced at day 56 in the active group only (p = 0.02, 0.02, and 0.04, respectively). Muscle bioenergetics and heart rate variability showed no change between arms. There were significant improvements in digit span and a neurocognitive test (p = 0.03), and upon acute nVNS stimulation, frontal region alpha reactivity showed a significant negative relationship with fatigue scores in the active group (p < 0.01).

CONCLUSIONS

We observed significant improvements in three measures of fatigue at day 56 with the active device but not the sham device. Directly after device use, fatigue levels correlate with measures of alpha reactivity, suggesting modulation of cholinergic system integrity as a mechanism of action for nVNS.

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.

Safety and tolerability of adjunct non-invasive vagus nerve stimulation in people with parkinson's: a study protocol

BACKGROUND

Parkinson's disease (PD) is the fastest growing neurological condition worldwide. Recent theories suggest that symptoms of PD may arise due to spread of Lewy-body pathology where the process begins in the gut and propagate transynaptically via the vagus nerve to the central nervous system. In PD, gait impairments are common motor manifestations that are progressive and can appear early in the disease course. As therapies to mitigate gait impairments are limited, novel interventions targeting these and their consequences, i.e., reducing the risk of falls, are urgently needed. Non-invasive vagus nerve stimulation (nVNS) is a neuromodulation technique targeting the vagus nerve. We recently showed in a small pilot trial that a single dose of nVNS improved (decreased) discrete gait variability characteristics in those receiving active stimulation relative to those receiving sham stimulation. Further multi-dose, multi-session studies are needed to assess the safety and tolerability of the stimulation and if improvement in gait is sustained over time.

DESIGN

This will be an investigator-initiated, single-site, proof-of-concept, double-blind sham-controlled randomised pilot trial in 40 people with PD. Participants will be randomly assigned on a 1:1 ratio to receive either active or sham transcutaneous cervical VNS. All participants will undergo comprehensive cognitive, autonomic and gait assessments during three sessions over 24 weeks, in addition to remote monitoring of ambulatory activity and falls, and exploratory analyses of cholinergic peripheral plasma markers. The primary outcome measure is the safety and tolerability of multi-dose nVNS in PD. Secondary outcomes include improvements in gait, cognition and autonomic function that will be summarised using descriptive statistics.

DISCUSSION

This study will report on the proportion of eligible and enrolled patients, rates of eligibility and reasons for ineligibility. Adverse events will be recorded informing on the safety and device tolerability in PD. This study will additionally provide us with information for sample size calculations for future studies and evidence whether improvement in gait control is enhanced when nVNS is delivered repeatedly and sustained over time.

TRIAL REGISTRATION

This trial is prospectively registered at www.isrctn.com/ISRCTN19394828 . Registered August 23, 2021.

Brain mapping inflammatory-arthritis-related fatigue in the pursuit of novel therapeutics

Despite developments in pharmacological treatments, chronic fatigue is an unresolved issue for most people with inflammatory arthritis that severely disrupts their personal and working lives. Fatigue in these patients is not strongly linked with peripheral disease activity but is associated with CNS-derived symptoms such as chronic pain, sleep disturbance, and depression. Therefore, a neurobiological basis should be considered when pursuing novel fatigue-specific therapeutics. In this Review, we focus on clinical imaging biomarkers that map candidate brain regions and are crucial in fatigue pathophysiology. We then evaluate neuromodulation techniques that could affect these candidate brain regions and are potential treatment strategies for fatigue in patients with inflammatory arthritis. We delineate work that is still required for neuroimaging and neuromodulation to eventually become part of a clinical pathway to treat and manage fatigue.

Long COVID: mechanisms, risk factors and recovery

NEW FINDINGS

What is the topic of this review? The emerging condition of long COVID, its epidemiology, pathophysiological impacts on patients of different backgrounds, physiological mechanisms emerging as explanations of the condition, and treatment strategies being trialled. The review leads from a Physiological Society online conference on this topic. What advances does it highlight? Progress in understanding the pathophysiology and cellular mechanisms underlying Long COVID and potential therapeutic and management strategies.

ABSTRACT

Long COVID, the prolonged illness and fatigue suffered by a small proportion of those infected with SARS-CoV-2, is placing an increasing burden on individuals and society. A Physiological Society virtual meeting in February 2022 brought clinicians and researchers together to discuss the current understanding of long COVID mechanisms, risk factors and recovery. This review highlights the themes arising from that meeting. It considers the nature of long COVID, exploring its links with other post-viral illnesses such as myalgic encephalomyelitis/chronic fatigue syndrome, and highlights how long COVID research can help us better support those suffering from all post-viral syndromes. Long COVID research started particularly swiftly in populations routinely monitoring their physical performance - namely the military and elite athletes. The review highlights how the high degree of diagnosis, intervention and monitoring of success in these active populations can suggest management strategies for the wider population. We then consider how a key component of performance monitoring in active populations, cardiopulmonary exercise training, has revealed long COVID-related changes in physiology - including alterations in peripheral muscle function, ventilatory inefficiency and autonomic dysfunction. The nature and impact of dysautonomia are further discussed in relation to postural orthostatic tachycardia syndrome, fatigue and treatment strategies that aim to combat sympathetic overactivation by stimulating the vagus nerve. We then interrogate the mechanisms that underlie long COVID symptoms, with a focus on impaired oxygen delivery due to micro-clotting and disruption of cellular energy metabolism, before considering treatment strategies that indirectly or directly tackle these mechanisms. These include remote inspiratory muscle training and integrated care pathways that combine rehabilitation and drug interventions with research into long COVID healthcare access across different populations. Overall, this review showcases how physiological research reveals the changes that occur in long COVID and how different therapeutic strategies are being developed and tested to combat this condition.

Bioelectronic medicine: Preclinical insights and clinical advances

The nervous system maintains homeostasis and health. Homeostatic disruptions underlying the pathobiology of many diseases can be controlled by bioelectronic devices targeting CNS and peripheral neural circuits. New insights into the regulatory functions of the nervous system and technological developments in bioelectronics drive progress in the emerging field of bioelectronic medicine. Here, we provide an overview of key aspects of preclinical research, translation, and clinical advances in bioelectronic medicine.

Transcutaneous Auricular Vagus Nerve Stimulation Improves Inflammation but Does Not Interfere with Cardiac Modulation and Clinical Symptoms of Individuals with COVID-19: A Randomized Clinical Trial

Transcranial auricular vagus nerve stimulation (taVNS) has shown effectiveness in reducing inflammation and depression. Thus, this study evaluated its effect on inflammation, cardiac autonomic modulation, and clinical symptoms in individuals affected by COVID-19. Methods: There were 52 randomized participants hospitalized with COVID-19 diagnosis who were to receive active (a-taVNS) or sham taVNS (s-taVNS) for 90 min twice a day for seven consecutive days. Interleukin 6 (IL-6), 10 (IL-10), cortisol, C-reactive protein (CRP), heart rate variability (HRV), and clinical symptoms were assessed before and after seven days of treatment. There were also seven- and fourteen-day follow-ups for clinical symptoms, including anxiety and depression levels, as well as a six-month follow-up for memory and attention levels. Results: There was significant reduction in CRP −23.9%, (95% CI −46.3 to −1.4) and IL-6 −37.7%, (95% CI −57.6 to −17.7) for the a-taVNS group. There were no changes in IL-10, cortisol levels, or in HRV results (p > 0.05) in both groups. There were no changes regarding clinical symptoms, except for a significant decrease in depression level (−2.85, 95% CI −5.44 to −0.27) in the a-taVNS group. Conclusion: taVNS showed effects on CRP, IL-6, and depression levels; however, it did not affect other clinical symptoms.

Vagus nerve stimulation as a novel treatment for systemic lupus erythematous: study protocol for a randomised, parallel-group, sham-controlled investigator-initiated clinical trial, the SLE-VNS study

INTRODUCTION

Systemic lupus erythematosus (SLE) is a chronic autoimmune disease. SLE is treated with immunosuppressants with suboptimal efficacy and high risk of serious side effects. Patients with SLE have increased risk of mortality, organ damage and debilitating treatment-resistant fatigue. Autonomic nervous system dysfunction (AD) is present in approximately half of the patients and may promote autoimmunity by weakening the vagally mediated anti-inflammatory reflex. Recent studies suggest that transcutaneous vagus nerve stimulation (tVNS) has few side effects and beneficial effects on fatigue, pain, disease activity and organ function. This study investigates whether adjuvant tVNS improves measures of fatigue (primary end point), AD, clinical disease activity, inflammation, pain, organ function and quality of life.Hence, this study will contribute to the understanding of AD as a potentially important precursor of fatigue, disease activity, progression and complications in SLE, and how tVNS mechanistically may attenuate this. As adjuvant tVNS use may reduce the need for traditional immunosuppressive therapy, this trial may prompt a shift in the treatment of SLE and potentially other autoimmune disorders.

METHODS AND ANALYSIS

Eighty-four patients with SLE with fatigue and AD will be randomised 1:1 to active or sham tVNS in this double-blinded parallel-group study. In period 1 (1 week), participants will receive a 4 min tVNS 4 times daily and report on fatigue daily. After a 2-week pause, period 2 (8 weeks) will entail tVNS twice daily and participants will report on fatigue, pain and disease activity weekly. Secondary end points will be assessed before and after each period and after 1 week in period 2.

ETHICS AND DISSEMINATION

The study is approved by the Danish Medical Research Ethical Committees (case no: 2120231) and results will be published in international peer-reviewed journals.

TRIAL REGISTRATION NUMBER

NCT05315739.

Manipulation of the inflammatory reflex as a therapeutic strategy

The cholinergic anti-inflammatory pathway is the efferent arm of the inflammatory reflex, a neural circuit through which the CNS can modulate peripheral immune responses. Signals communicated via the vagus and splenic nerves use acetylcholine, produced by Choline acetyltransferase (ChAT)+ T cells, to downregulate the inflammatory actions of macrophages expressing α7 nicotinic receptors. Pre-clinical studies using transgenic animals, cholinergic agonists, vagotomy, and vagus nerve stimulation have demonstrated this pathway's role and therapeutic potential in numerous inflammatory diseases. In this review, we summarize what is understood about the inflammatory reflex. We also demonstrate how pre-clinical findings are being translated into promising clinical trials, and we draw particular attention to innovative bioelectronic methods of harnessing the cholinergic anti-inflammatory pathway for clinical use.

Neuromodulation Strategies to Reduce Inflammation and Improve Lung Complications in COVID-19 Patients

Since the outbreak of the COVID-19 pandemic, races across academia and industry have been initiated to identify and develop disease modifying or preventative therapeutic strategies has been initiated. The primary focus has been on pharmacological treatment of the immune and respiratory system and the development of a vaccine. The hyperinflammatory state ("cytokine storm") observed in many cases of COVID-19 indicates a prognostically negative disease progression that may lead to respiratory distress, multiple organ failure, shock, and death. Many critically ill patients continue to be at risk for significant, long-lasting morbidity or mortality. The human immune and respiratory systems are heavily regulated by the central nervous system, and intervention in the signaling of these neural pathways may permit targeted therapeutic control of excessive inflammation and pulmonary bronchoconstriction. Several technologies, both invasive and non-invasive, are available and approved for clinical use, but have not been extensively studied in treatment of the cytokine storm in COVID-19 patients. This manuscript provides an overview of the role of the nervous system in inflammation and respiration, the current understanding of neuromodulatory techniques from preclinical and clinical studies and provides a rationale for testing non-invasive neuromodulation to modulate acute systemic inflammation and respiratory dysfunction caused by SARS-CoV-2 and potentially other pathogens. The authors of this manuscript have co-founded the International Consortium on Neuromodulation for COVID-19 to advocate for and support studies of these technologies in the current coronavirus pandemic.

Non-invasive Vagus Nerve Stimulation for COVID-19: Results From a Randomized Controlled Trial (SAVIOR I)

Background

Severe coronavirus disease 2019 (COVID-19) is characterized, in part, by an excessive inflammatory response. Evidence from animal and human studies suggests that vagus nerve stimulation can lead to reduced levels of various biomarkers of inflammation. We conducted a prospective randomized controlled study (SAVIOR-I) to assess the feasibility, efficacy, and safety of non-invasive vagus nerve stimulation (nVNS) for the treatment of respiratory symptoms and inflammatory markers among patients who were hospitalized for COVID-19 (ClinicalTrials.gov identifier: NCT04368156).

Methods

Participants were randomly assigned in a 1:1 allocation to receive either the standard of care (SoC) alone or nVNS therapy plus the SoC. The nVNS group received 2 consecutive 2-min doses of nVNS 3 times daily as prophylaxis. Efficacy and safety were evaluated via the incidence of specific clinical events, inflammatory biomarker levels, and the occurrence of adverse events.

Results

Of the 110 participants who were enrolled and randomly assigned, 97 (nVNS, n = 47; SoC, n = 50) had sufficient available data and comprised the evaluable population. C-reactive protein (CRP) levels decreased from baseline to a significantly greater degree in the nVNS group than in the SoC group at day 5 and overall (i.e., all postbaseline data points collected through day 5, combined). Procalcitonin level also showed significantly greater decreases from baseline to day 5 in the nVNS group than in the SoC group. D-dimer levels were decreased from baseline for the nVNS group and increased from baseline for the SoC group at day 5 and overall, although the difference between the treatment groups did not reach statistical significance. No significant treatment differences were seen for clinical respiratory outcomes or any of the other biochemical markers evaluated. No serious nVNS-related adverse events occurred during the study.

Conclusions

nVNS therapy led to significant reductions in levels of inflammatory markers, specifically CRP and procalcitonin. Because nVNS has multiple mechanisms of action that may be relevant to COVID-19, additional research into its potential use earlier in the course of COVID-19 and its potential to mitigate some of the symptoms associated with post-acute sequelae of COVID-19 is warranted.

Exploring the vagus nerve and the inflammatory reflex for therapeutic benefit in chronic spinal cord injury

PURPOSE OF REVIEW

To describe features and implications of chronic systemic inflammation in individuals with spinal cord injury (SCI) and to summarize the growing therapeutic possibilities to explore the vagus nerve-mediated inflammatory reflex in this context.

RECENT FINDINGS

The discovery of the inflammatory reflex provides a rationale to explore neuromodulation modalities, that is, electrical vagus nerve stimulation and pharmacological cholinergic modalities to regulate inflammation after SCI.

SUMMARY

Inflammation in individuals with SCI may negatively impact functional recovery and medical consequences after SCI. Exploring the potential of the vagus nerve-based inflammatory reflex to restore autonomic regulation and control inflammation may provide a novel approach for functional improvement in SCI.

Effect of Transcutaneous Vagus Nerve Stimulation in Erosive Hand Osteoarthritis: Results from a Pilot Trial

Beyond its effect on vegetative functions, the activation of the vagus nerve inhibits inflammation and reduces pain signaling. The aim of this open-label pilot study was to determine the efficacy and tolerance of transcutaneous auricular VNS (taVNS) on erosive hand osteoarthritis (EHOA) symptoms. Symptomatic EHOA patients with hand pain VAS ≥ 40/100 mm and ≥1 interphalangeal swollen joint(s) were included. The taVNS was performed for 4 weeks using an auricular electrode applied one hour per day and connected to a TENS device with pre-established settings. Clinical efficacy was evaluated by changes between baseline and at 4 weeks with hand pain VAS and the functional index FIHOA score, using a Wilcoxon t-test. The treatment tolerance was also evaluated. Eighteen patients (median age 69 years old, 83% women) were analyzed. At baseline, hand pain VAS was 60 mm [IQR 50; 78.2] and FIHOA 15 [10.7; 20.2]. After 4 weeks, taVNS significantly reduced hand pain VAS, with a median decrease of 23.5 mm [7.7; 37.2] (p = 0.001), as well as FIHOA, with a median decrease of 2 points [0.75; 5.2] (p = 0.01). No serious adverse events were reported. One patient stopped taVNS because of auricular discomfort. This first proof-of-concept trial indicated that taVNS is feasible and may decrease joint inflammation and clinical symptoms in EHOA, arguing for a randomized controlled study versus sham stimulation.

Structural and functional connections between the autonomic nervous system, hypothalamic-pituitary-adrenal axis, and the immune system: a context and time dependent stress response network

The autonomic nervous system (ANS), hypothalamic-pituitary-adrenal (HPA) axis, and immune system are connected anatomically and functionally. These three systems coordinate the central and peripheral response to perceived and systemic stress signals. Both the parasympathetic and sympathetic components of the autonomic nervous system rapidly respond to stress signals, while the hypothalamic-pituitary-adrenal axis and immune system have delayed but prolonged actions. In vitro, animal, and human studies have demonstrated consistent anti-inflammatory effects of parasympathetic activity. In contrast, sympathetic activity exerts context-dependent effects on immune signaling and has been associated with both increased and decreased inflammation. The location of sympathetic action, adrenergic receptor subtype, and timing of activity in relation to disease progression all influence the ultimate impact on immune signaling. This article reviews the brain circuitry, peripheral connections, and chemical messengers that enable communication between the ANS, HPA axis, and immune system. We describe findings of in vitro and animal studies that challenge the immune system with lipopolysaccharide. Next, neuroimmune connections in animal models of chronic inflammatory disease are reviewed. Finally, we discuss how a greater understanding of the ANS-HPA-immune network may lead to the development of novel therapeutic strategies that are focused on modulation of the sympathetic and parasympathetic nervous system.

Peripheral nerve stimulation and immunity: the expanding opportunities for providing mechanistic insight and therapeutic intervention

Pre-clinical research advances our understanding of the vagus nerve-mediated regulation of immunity and clinical trials successfully utilize electrical vagus nerve stimulation in the treatment of patients with inflammatory disorders. This symbiotic relationship between pre-clinical and clinical research exploring the vagus nerve-based 'inflammatory reflex' has substantially contributed to establishing the field of bioelectronic medicine. Recent studies identify a crosstalk between the vagus nerve and other neural circuitries in controlling inflammation and delineate new neural immunoregulatory pathways. Here we outline current mechanistic insights into the role of vagal and non-vagal neural pathways in neuro-immune communication and inflammatory regulation. We also provide a timely overview of expanding opportunities for bioelectronic neuromodulation in the treatment of various inflammatory disorders.

Control of inflammation using non-invasive neuromodulation: past, present and promise

The nervous system has been increasingly recognized as a novel and accessible target in the regulation of inflammation. The use of implantable and invasive devices targeting neural circuits has yielded successful results in clinical settings but does have some risk or adverse effects. Recent advances in technology and understanding of mechanistic pathways have opened new avenues of non-invasive neuromodulation. Through this review we discuss the novel research and outcomes of major modalities of non-invasive neuromodulation in the context of inflammation including transcutaneous electrical, magnetic and ultrasound neuromodulation. In addition to highlighting the scientific observations and breakthroughs, we discuss the underlying mechanisms and pathways for neural regulation of inflammation.

Transcutaneous Cervical Vagal Nerve Stimulation in Patients with Posttraumatic Stress Disorder (PTSD): A Pilot Study of Effects on PTSD Symptoms and Interleukin-6 Response to Stress

BACKGROUND

Posttraumatic stress disorder (PTSD) is a highly disabling condition associated with alterations in multiple neurobiological systems, including increases in inflammatory and sympathetic function, responsible for maintenance of symptoms. Treatment options including medications and psychotherapies have limitations. We previously showed that transcutaneous Vagus Nerve Stimulation (tcVNS) blocks inflammatory (interleukin (IL)-6) responses to stress in PTSD. The purpose of this study was to assess the effects of tcVNS on PTSD symptoms and inflammatory responses to stress.

METHODS

Twenty patients with PTSD were randomized to double blind active tcVNS (N=9) or sham (N=11) stimulation in conjunction with exposure to personalized traumatic scripts immediately followed by active or sham tcVNS and measurement of IL-6 and other biomarkers of inflammation. Patients then self administered active or sham tcVNS twice daily for three months. PTSD symptoms were measured with the PTSD Checklist (PCL) and the Clinician Administered PTSD Scale (CAPS), clinical improvement with the Clinical Global Index (CGI) and anxiety with the Hamilton Anxiety Scale (Ham-A) at baseline and one-month intervals followed by a repeat of measurement of biomarkers with traumatic scripts. After three months patients self treated with twice daily open label active tcVNS for another three months followed by assessment with the CGI.

RESULTS

Traumatic scripts increased IL-6 in PTSD patients, an effect that was blocked by tcVNS (p<.05). Active tcVNS treatment for three months resulted in a 31% greater reduction in PTSD symptoms compared to sham treatment as measured by the PCL (p=0.013) as well as hyperarousal symptoms and somatic anxiety measured with the Ham-A p<0.05). IL-6 increased from baseline in sham but not tcVNS. Open label tcVNS resulted in improvements measured with the CGI compared to the sham treatment period p<0.05).

CONCLUSIONS

These preliminary results suggest that tcVNS reduces inflammatory responses to stress, which may in part underlie beneficial effects on PTSD symptoms.

The role of the cholinergic anti-inflammatory pathway in autoimmune rheumatic diseases

The cholinergic anti-inflammatory pathway (CAP) is a classic neuroimmune pathway, consisting of the vagus nerve, acetylcholine (ACh)-the pivotal neurotransmitter of the vagus nerve-and its receptors. This pathway can activate and regulate the activities of immune cells, inhibit cell proliferation and differentiation, as well as suppress cytokine release, thereby playing an anti-inflammatory role, and widely involved in the occurrence and development of various diseases; recent studies have demonstrated that the CAP may be a new target for the treatment of autoimmune rheumatic diseases. In this review, we will summarize the latest progress with the view of figuring out the role of the cholinergic pathway and how it interacts with inflammatory reactions in several autoimmune rheumatic diseases, and many advances are results from a wide range of experiments performed in vitro and in vivo.

Fatigue in inflammatory rheumatic diseases: current knowledge and areas for future research

Fatigue is a complex phenomenon and an important health concern for many people with chronic inflammatory rheumatic diseases, such as rheumatoid arthritis, psoriatic arthritis, primary Sjögren syndrome and systemic lupus erythematosus. Although some clinical trials have shown the benefits of cognitive behavioural therapy in fatigue management, the effect of this approach is relatively modest, and no curative treatment has been identified. The pathogenesis of fatigue remains unclear. Despite many challenges and limitations, a growing body of research points to roles for the immune system, the central and autonomic nervous systems and the neuroendocrine system in the induction and maintenance of fatigue in chronic diseases. New insights indicate that sleep, genetic susceptibility, metabolic disturbances and other biological and physiological mechanisms contribute to fatigue. Furthermore, understanding of the relationships between psychosocial factors and fatigue is increasing. However, the interrelationships between these diverse mechanisms and fatigue remain poorly defined. In this Review, we outline various biological, physiological and psychosocial determinants of fatigue in inflammatory rheumatic diseases, and propose mechanistic and conceptual models of fatigue to summarize current understanding, stimulate debate and develop further research ideas.

Noninvasive vagus nerve stimulation in Parkinson's disease: current status and future prospects

INTRODUCTION

Parkinson's disease (PD) is a common progressive neurodegenerative disorder with multifactorial etiology. While dopaminergic medication is the standard therapy in PD, it provides limited symptomatic treatment and non-pharmacological interventions are currently being trialed.

AREAS COVERED

Recent pathophysiological theories of Parkinson's suggest that aggregated α-synuclein form in the gut and spread to nuclei in the brainstem via autonomic connections. In this paper, we review the novel hypothesis that noninvasive vagus nerve stimulation (nVNS), targeting efferent and afferent vagal projections, is a promising therapeutic tool to improve gait and cognitive control and ameliorate non-motor symptoms in people with Parkinson's. We conducted an unstructured search of the literature for any studies employing nVNS in PD as well as for studies examining the efficacy of nVNS on improving cognitive function and where nVNS has been applied to co-occurring conditions in PD.

EXPERT OPINION

Evidence of nVNS as a novel therapeutic to improve gait in PD is preliminary, but early signs indicate the possibility that nVNS may be useful to target dopa-resistant gait characteristics in early PD. The evidence for nVNS as a therapeutic tool is, however, limited and further studies are needed in both brain health and disease.

Autonomic Nervous System Dysfunction in Primary Sjögren's Syndrome

Primary Sjögren's syndrome (pSS) is an autoimmune disease which primarily affects the exocrine glands, but can also affect other organs, including the nervous system. Many studies have reported evidence of autonomic nervous system (ANS) dysfunction in pSS which may contribute to a wide range of symptoms and functional burden. Symptoms of ANS dysfunction are common and widespread among patients with pSS and are associated with other features of the disease, particularly fatigue. Accumulating data on the inter-relationship between the ANS and the immune system via the vagus nerve have been reported. Vagus nerve stimulation (VNS) has also been associated with improvement in fatigue in patients with pSS. Taken together, these data suggest that the ANS may be a potential treatment target for pSS, in particularly those with fatigue being a predominant symptom. Future research to dissect the link between the ANS, immune dysregulation and clinical manifestations in pSS and to evaluate the potential of VNS as a therapy for pSS is warranted.

Understanding Fatigue in Sjögren's Syndrome: Outcome Measures, Biomarkers and Possible Interventions

Sjögren’s syndrome (SS) is an autoimmune disease affecting the salivary and lacrimal glands. Symptoms range from dryness to severe extra-glandular disease involving manifestations in the skin, lungs, nervous system, and kidney. Fatigue occurs in 70% of patients, characterizing primary SS (pSS) and significantly impacting the patient’s quality of life. There are some generic and specific instruments used to measure fatigue in SS. The mechanisms involved with fatigue in SS are still poorly understood, but it appears fatigue signaling pathways are more associated with cell protection and defense than with pro-inflammatory pathways. There are no established pharmacological treatment options for fatigue in pSS. So far, exercise and neuromodulation techniques have shown positive effects on fatigue in pSS. This study briefly reviews fatigue in pSS, with special attention to outcome measures, biomarkers, and possible treatment options.