BACKGROUND: Hepatic inflammatory cell accumulation and the subsequent systematic inflammation drive acute-on-chronic liver failure (ACLF) development. Previous studies showed that the vagus nerve exerts anti-inflammatory activity in many inflammatory diseases. Here, we aimed to identify the key molecule mediating the inflammatory process in ACLF and reveal the neuroimmune communication arising from the vagus nerve and immunological disorders of ACLF. METHODS: Proteomic analysis was performed and validated in ACLF model mice or patients, and intervention animal experiments were conducted using neutralizing antibodies. PNU-282987 (acetylcholine receptor agonist) and vagotomy were applied for perturbing vagus nerve activity. Single-cell RNA sequencing (scRNA-seq), flow cytometry, immunohistochemical and immunofluorescence staining, and clustered regularly interspaced short palindromic repeats/CRISPR-associated protein 9 (CRISPR/Cas9) technology were used for in vivo or in vitro mechanistic studies. RESULTS: The unbiased proteomics identified C-X-C motif chemokine ligand 9 (CXCL9) as the greatest differential protein in the livers of mice with ACLF and its relation to the systematic inflammation and mortality were confirmed in patients with ACLF. Interventions on CXCL9 and its receptor C-X-C chemokine receptor 3 (CXCR3) improved liver injury and decreased mortality of ACLF mice, which were related to the suppressing of hepatic immune cells' accumulation and activation. Vagus nerve stimulation attenuated while vagotomy aggravated the expression of CXCL9 and the severity of ACLF. Blocking CXCL9 and CXCR3 ameliorated liver inflammation and increased ACLF-associated mortality in ACLF mice with vagotomy. scRNA-seq revealed that hepatic macrophages served as the major source of CXCL9 in ACLF and were validated by immunofluorescence staining and flow cytometry analysis. Notably, the expression of CXCL9 in macrophages was modulated by vagus nerve-mediated cholinergic signaling. CONCLUSIONS Our novel findings highlighted that the neuroimmune communication of the vagus nerve-macrophage-CXCL9 axis contributed to ACLF development. These results provided evidence for neuromodulation as a promising approach for preventing and treating ACLF.
Animals ; Mice ; Chemokine CXCL9/metabolism* ; Vagus Nerve/physiology* ; Acute-On-Chronic Liver Failure/metabolism* ; Humans ; Male ; Mice, Inbred C57BL ; Proteomics ; Flow Cytometry ; Receptors, CXCR3/metabolism*

Atrial fibrillation (AF) is the most common arrhythmia in clinical practice. It has a high prevalence and poor prognosis. The application of antiarrhythmic drugs and even surgery cannot completely treat the disease, and there are many sequelae. AF can be classified into the category of "palpitation" in Chinese medicine according to its symptoms. Acupuncture has a significant effect on AF. The authors find that an important mechanism of acupuncture in AF treatment is to regulate the cardiac vagus nerve. Therefore, this article intends to review the distribution and function of vagus nerve in the heart, the application and the regulatroy effect for the treatment of AF.
Atrial Fibrillation/physiopathology* ; Humans ; Acupuncture Therapy ; Vagus Nerve/physiology* ; Animals

OBJECTIVE: To observe the effect of transcutaneous auricular vagus nerve stimulation (taVNS) on the sleep quality and nocturnal heart rate variability (HRV) in patients with primary insomnia. METHODS: Twenty-one patients with primary insomnia were included. Using SDZ-ⅡB electric acupuncture apparatus, Xin (CO₁₅) and Shen (CO₁₀) were stimulated with disperse-dense wave, 4 Hz/ 20 Hz in frequency, (0.2±30%) ms of pulse width and tolerable intensity. Electric stimulation was given once every morning and evening of a day, 30 min each time, for 4 weeks totally. Before and after treatment, the score of Pittsburgh sleep quality index (PSQI), objective sleep structure (total sleep time [TST], sleep latency [SL], wake after sleep onset [WASO], sleep efficiency [SE], the percentages of non-rapid eye movement period 1, 2, 3, and the percentage of rapid eye movement period to TST [N1%, N2%, N3%, REM%] ) and nocturnal HRV (high frequency [HF], low frequency [LF], the ratio of LF to HF [LF/HF], standard deviation for the normal RR intervals [SDNN], squared root of the mean sum of squares of differences between adjacent intervals RR [RMSSD], the percentage of adjacent RR intervals with differences larger than 50 ms in the entire recording [PNN50%], the mean of sinus RR intervals [NNMean] ) were compared in the patients separately. RESULTS: After treatment, the score of each item and the total score of PSQI and SL were all reduced as compared with those before treatment (P<0.01, P<0.001); SE, N3%, LF, HF, LF/HF, SDNN, NNMean and RMSSD were all increased compared with those before treatment (P<0.001, P<0.01). CONCLUSION The taVNS improves the sleep quality and objective sleep structure in patients with primary insomnia, which is probably related to the regulation of autonomic nervous functions.
Heart Rate/physiology* ; Humans ; Sleep/physiology* ; Sleep Initiation and Maintenance Disorders/therapy* ; Vagus Nerve ; Vagus Nerve Stimulation

OBJECTIVE: To explore the modulation of transcutaneous auricular vagus nerve stimulation (taVNS) on default mode network (DMN) in patients with primary insomnia (PI). METHODS: A total of 22 PI patients (one patient dropped off and two patients were excluded) were included and treated with taVNS. The bilateral auricular points of Xin (CO₁₅) and Shen (CO₁₀) were selected and treated with disperse-dense wave at frequency of 4 Hz/20 Hz, the intensity was based on the patient's tolerance. taVNS was given once in the morning and once in the evening for 30 minutes each time. The treatment lasted for at least 5 days a week for 4 weeks. At the same time, 16 healthy subjects matched with gender and age were recruited. The Pittsburgh sleep quality index (PSQI) score was evaluated before and after treatment in PI patients. The resting-state functional magnetic resonance imaging (rs-fMRI) data of PI patients before and after treatment and healthy subjects at baseline period were collected to observe the effect of taVNS on the functional connection (FC) between posterior cingulate cortex (PCC) and whole brain. RESULTS: After treatment, the total score of PSQI in PI patients was lower than that before treatment (P<0.01). Compared with healthy subjects, the FC of the left PCC was increased either with the left orbital superior frontal gyrus or with left middle frontal gyrus (P<0.001), and the FC between right PCC and left middle frontal gyrus was increased in PI patients before treatment (P<0.001). Compared before treatment, the FC between left PCC and left middle frontal gyrus was decreased (P<0.05), and the FC of the right PCC was decreased either with the right medial prefrontal cortex or with the left middle frontal gyrus in PI patients after treatment (P<0.001, P<0.01). CONCLUSION taVNS can modulate the FC between anterior and posterior DMN, and between DMN and cognitive control network of PI patients, which may be one of the brain effect mechanisms of taVNS in the treatment of PI patients.
Brain/physiology* ; Default Mode Network ; Humans ; Magnetic Resonance Imaging/methods* ; Sleep Initiation and Maintenance Disorders/therapy* ; Vagus Nerve ; Vagus Nerve Stimulation/methods*

Excessive reactive oxygen species (ROS) (such as the superoxide radical) are commonly associated with cardiac autonomic dysfunctions. Though superoxide dismutase 1 (SOD1) overexpression may protect against ROS damage to the autonomic nervous system, superoxide radical reduction may change normal physiological functions. Previously, we demonstrated that human SOD1 (hSOD1) overexpression does not change baroreflex bradycardia and tachycardia but rather increases aortic depressor nerve activity in response to arterial pressure changes in C57B6SJL-Tg (SOD1)2 Gur/J mice. Since the baroreflex arc includes afferent, central, and efferent components, the objective of this study was to determine whether hSOD1 overexpression alters the central and vagal efferent mediation of heart rate (HR) responses. Our data indicate that SOD1 overexpression decreased the HR responses to vagal efferent nerve stimulation but did not change the HR responses to aortic depressor nerve (ADN) stimulation. Along with the previous study, we suggest that SOD1 overexpression preserves normal baroreflex function but may differentially alter the functions of the ADN, vagal efferents, and central components. While SOD1 overexpression likely enhanced ADN function and the central mediation of bradycardia, it decreased vagal efferent control of HR.
Animals ; Baroreflex ; physiology ; Blood Pressure ; physiology ; Bradycardia ; metabolism ; Heart Rate ; physiology ; Humans ; Mice, Transgenic ; Superoxide Dismutase-1 ; metabolism ; Vagus Nerve ; metabolism

The autonomic nervous system plays critical roles in maintaining homeostasis in humans, directly regulating inflammation by altering the activity of the immune system. The cholinergic anti-inflammatory pathway is a well-studied neuroimmune interaction involving the vagus nerve. CD4-positive T cells expressing β2 adrenergic receptors and macrophages expressing the alpha 7 subunit of the nicotinic acetylcholine receptor in the spleen receive neurotransmitters such as norepinephrine and acetylcholine and are key mediators of the cholinergic anti-inflammatory pathway. Recent studies have demonstrated that vagus nerve stimulation, ultrasound, and restraint stress elicit protective effects against renal ischemia-reperfusion injury. These protective effects are induced primarily via activation of the cholinergic anti-inflammatory pathway. In addition to these immunological roles, nervous systems are directly related to homeostasis of renal physiology. Whole-kidney three-dimensional visualization using the tissue clearing technique CUBIC (clear, unobstructed brain/body imaging cocktails and computational analysis) has illustrated that renal sympathetic nerves are primarily distributed around arteries in the kidneys and denervated after ischemia-reperfusion injury. In contrast, artificial renal sympathetic denervation has a protective effect against kidney disease progression in murine models. Further studies are needed to elucidate how neural networks are involved in progression of kidney disease.
Acetylcholine ; Arteries ; Autonomic Nervous System ; Cholinergic Neurons ; Homeostasis ; Humans ; Immune System ; Inflammation ; Kidney Diseases ; Kidney ; Macrophages ; Nervous System ; Neurotransmitter Agents ; Norepinephrine ; Optogenetics ; Physiology ; Receptors, Adrenergic ; Receptors, Nicotinic ; Reperfusion Injury ; Spleen ; Sympathectomy ; Sympathetic Nervous System ; T-Lymphocytes ; Ultrasonography ; Vagus Nerve ; Vagus Nerve Stimulation

Obesity is a prevalent disease with significant morbidity and mortality. It is a state of chronic low-grade inflammation due to excess body fat. Weight homeostasis is maintained through changes in various gastrointestinal hormones caused by dietary intake. However, being overweight or obese breaks the balance of these appetite-related gastrointestinal hormones and creates resistance to the actions of these hormones. The sensitivity of vagal afferent neurons to peripheral signals becomes blunted. Cytokines produced by excessive fat tissue damage our normal immune system, making us vulnerable to infection. In addition, various changes in gastrointestinal motility occur. Therefore, this review focuses on the various changes in gastrointestinal hormones, the immune state, the vagus nerve, and gastrointestinal movement in obese patients.
Adipose Tissue ; Cytokines ; Gastrointestinal Hormones ; Gastrointestinal Motility ; Homeostasis ; Humans ; Immune System ; Inflammation ; Mortality ; Neurons, Afferent ; Obesity ; Overweight ; Physiology ; Vagus Nerve

Treatment by auricular acupuncture has a long history. Ear-acupoint research has been advancing step by step in China and also in Europe. Auricles are rich in nerves, therefore a close relationship with different functions of the human body has been proved by the research teams of the two main authors of this article from China and Austria. In recent years, great progress has been made in the research of regulating human body functions through electroacupuncture at the auricular branch of the vagus nerve, which is part of auricular acupuncture therapy. It is well known that the auricular branch of the vagus nerve is the only peripheral pathway to the cerebral cortex. Studies of the Chinese team on hypertension, diabetes, epilepsy and depression have shown that the mechanism of auricular vagus nerve stimulation (VNS) may be comparable with cervical VNS in terms of pathways. Auricular VNS has a broad clinical application prospect.
Acupuncture, Ear ; Animals ; Austria ; Biomedical Research ; China ; Depression ; therapy ; Electric Stimulation Therapy ; Electroacupuncture ; Electroencephalography ; Epilepsy ; therapy ; Humans ; International Cooperation ; Reflex ; physiology ; Vagus Nerve ; physiology

OBJECTIVETo observe abnormalities in heart rate variability (HRV) in diabetic rats and to explore the effects of treatment with Guizhi Decoction ([symbols; see text]) on cardiac autonomic nervous (CAN) imbalance.

METHODSA radio-telemetry system for monitoring physiological parameters was implanted into rats to record electrocardiac signals and all indictors of HRV [time domain measures: standard deviation of all RR intervals in 24 h (SDNN), root mean square of successive differences (RMSSD), percentage of differences between adjacent RR intervals greater than 50 ms (PNN50), and standard deviation of the averages of RR intervals (SDANN); frequency domain measures: low frequency (LF), high frequency (HF), total power (TP), and LF/HF ratio]. The normal group was randomly selected, and the remaining rats were used to establish streptozocin (STZ)-induced diabetic model. After 4 weeks, the model rats were divided into the model group, the methycobal group, and the Guizhi Decoction group, 9 rats in each group. Four weeks after intragastric administration of the corresponding drugs, the right atria of the rats were collected for immunohistochemical staining of tyrosine hydroxylase (TH) and choline acetyltransferase (CHAT) to observe the distribution of the sympathetic and vagus nerves in the right atrium. The myocardial homogenate from the interventricular septum and the left ventricle was used for determination of TH, CHAT, growth-associated protein 43 (GAP-43), nerve growth factor (NGF), and ciliary neurotrophic factor (CNTF) levels using an enzyme-linked immunosorbent assay.

RESULTS(1) STZ rats had elevated blood glucose levels, reduced body weight, and decreased heart rate; there was no difference between the model group and the drug treated groups. (2) Compared with the model group, only RMSSD and TP increased in the methycobal group significantly (P<0.05); SDNN, RMSSD, PNN50, LF, HF, and TP increased, LF/HF decreased (P<0.05), and SDANN just showed a decreasing trend in the Guizhi Decoction group (P>0.05). TH increased, CHAT decreased, and TH/CHAT increased in the myocardial homogenate of the model group (P<0.05). Compared with the model group, left ventricular TH reduced in the methycobal group; and in the Guizhi Decoction group CHAT increased, while TH and TH/CHAT decreased (P<0.05). Compared with the model group, CNTF in the interventricular septum increased in the methycobal group (P<0.05); GAP-43 increased, NGF decreased, and CNTF increased (P<0.05) in the Guizhi Decoction group. There were significant differences in the reduction of NGF and elevation of CNTF between the Guizhi Decoction group and the methycobal group (P<0.05). (3) Immunohistochemical results showed that TH expression significantly increased and CHAT expression significantly decreased in the myocardia of the model group, whereas TH expression decreased and CHAT expression increased in the Guizhi Decoction group (P<0.05).

CONCLUSIONGuizhi Decoction was effective in improving the function of the vagus nerve, and it could alleviate autonomic nerve damage.

Animals ; Autonomic Nervous System ; drug effects ; physiopathology ; Choline O-Acetyltransferase ; metabolism ; Diabetes Mellitus, Experimental ; drug therapy ; physiopathology ; Diabetic Neuropathies ; drug therapy ; physiopathology ; Disease Models, Animal ; Drugs, Chinese Herbal ; pharmacology ; Heart ; innervation ; physiopathology ; Heart Rate ; drug effects ; physiology ; Male ; Monitoring, Physiologic ; methods ; Rats, Wistar ; Telemetry ; methods ; Treatment Outcome ; Tyrosine 3-Monooxygenase ; metabolism ; Vagus Nerve ; drug effects ; physiopathology

Natural toxic substances have a bitter taste and their ingestion sends signals to the brain leading to aversive oral sensations. In the present study, we investigated chronological changes in c-Fos immunoreactivity in the nucleus tractus solitarius (NTS) to study the bitter taste reaction time of neurons in the NTS. Equal volumes (0.5 mL) of denatonium benzoate (DB), a bitter tastant, or its vehicle (distilled water) were administered to rats intragastrically. The rats were sacrificed at 0, 0.5, 1, 2, 4, 8, or 16 h after treatment. In the vehicle-treated group, the number of c-Fos-positive nuclei started to increase 0.5 h after treatment and peaked 2 h after gavage. In contrast, the number of c-Fos-positive nuclei in the DB-treated group significantly increased 1 h after gavage. Thereafter, the number of c-Fos immunoreactive nuclei decreased over time. The number of c-Fos immunoreactive nuclei in the NTS was also increased in a dose-dependent manner 1 h after gavage. Subdiaphragmatic vagotomy significantly decreased DB-induced neuronal activation in the NTS. These results suggest that intragastric DB increases neuronal c-Fos expression in the NTS 1 h after gavage and this effect is mediated by vagal afferent fibers.
Adjuvants, Immunologic/pharmacology ; Afferent Pathways/physiology ; Animals ; Injections/veterinary ; Ligands ; Male ; Proto-Oncogene Proteins c-fos/*metabolism ; Quaternary Ammonium Compounds/*pharmacology ; Rats ; Rats, Sprague-Dawley ; Receptors, G-Protein-Coupled/*metabolism ; Solitary Nucleus/*physiology ; Vagus Nerve/*drug effects/*physiology