Vagal efferent fiber stimulation ameliorates pulmonary microvascular endothelial cell injury by downregulating inflammatory responses

Preservation of the pulmonary branches of the vagus nerve during three-dimensional thoracoscopic radical resection of lung cancer: a retrospective study

BACKGROUND

In this study, we investigated the effect of preservation of the pulmonary branches of the vagus nerve during systematic dissection of mediastinal lymph nodes, when performing radical resection of lung cancer, on the postoperative complication rate.

METHODS

The clinical data for 80 patients who underwent three-dimensional thoracoscopic radical resection of lung cancer in the Department of Thoracic Surgery at Huizhou Municipal Central Hospital between 2020 and 2022 were analyzed. The patients were divided into two groups according to whether the pulmonary branches of the vagus nerve were retained during intraoperative carinal lymph node dissection. The operation time, time until first postoperative defecation, duration for which a chest tube was needed, total chest drainage volume, average pain intensity during the first 5 postoperative days, incidence of postoperative pneumonia, and postoperative length of stay were compared between the two groups.

RESULTS

There was no statistically significant difference in histological staging or in time until first postoperative defecation between the two groups (p > 0.05). However, there were significant differences in operation time, the duration for which a chest tube was needed, total chest drainage volume, average pain intensity during the first 5 postoperative days, white blood cell count and procalcitonin level on postoperative days 1 and 5, and postoperative length of stay between the two groups (p < 0.05).

CONCLUSION

Preserving the pulmonary branches of the vagus nerve during carinal lymph node dissection when performing three-dimensional thoracoscopic radical resection of lung cancer can reduce the risk of postoperative complications.

Critical evaluation of established risk prediction models for acute respiratory distress syndrome in adult patients: A systematic review and meta-analysis

AIM

To assess the performance of validated prediction models for acute respiratory distress syndrome (ARDS) by systematic review and meta-analysis.

METHODS

Eight databases (Medline, CINAHL, Embase, The Cochrane Library, CNKI, WanFang Data, Sinomed, and VIP) were searched up to March 26, 2023. Studies developed and validated a prediction model for ARDS in adult patients were included. Items on study design, incidence, derivation methods, predictors, discrimination, and calibration were collected. The risk of bias was assessed by the Prediction model Risk of Bias Assessment Tool. Models with a reported area under the curve of the receiver operating characteristic (AUC) metric were analyzed.

RESULTS

A total of 25 studies were retrieved, including 48 unique prediction models. Discrimination was reported in all studies, with AUC ranging from 0.701 to 0.95. Emerged AUC value of the logistic regression model was 0.837 (95% CI: 0.814 to 0.859). Besides, the value in the ICU group was 0.856 (95% CI: 0.812 to 0.899), the acute pancreatitis group was 0.863 (95% CI: 0.844 to 0.882), and the postoperation group was 0.835 (95% CI: 0.808 to 0.861). In total, 24 of the included studies had a high risk of bias, which was mostly due to the improper methods in predictor screening (13/24), model calibration assessment (9/24), and dichotomization of continuous predictors (6/24).

CONCLUSIONS

This study shows that most prediction models for ARDS are at high risk of bias, and the discrimination ability of the model is excellent. Adherence to standardized guidelines for model development is necessary to derive a prediction model of value to clinicians.

Exploring the Modulatory Effect of High-Fat Nutrition on Lipopolysaccharide-Induced Acute Lung Injury in Vagotomized Rats and the Role of the Vagus Nerve

During esophagectomy, the vagus nerve is transected, which may add to the development of postoperative complications. The vagus nerve has been shown to attenuate inflammation and can be activated by a high-fat nutrition via the release of acetylcholine. This binds to α7 nicotinic acetylcholine receptors (α7nAChR) and inhibits α7nAChR-expressing inflammatory cells. This study investigates the role of the vagus nerve and the effect of high-fat nutrition on lipopolysaccharide (LPS)-induced lung injury in rats. Firstly, 48 rats were randomized in 4 groups as follows: sham (sparing vagus nerve), abdominal (selective) vagotomy, cervical vagotomy and cervical vagotomy with an α7nAChR-agonist. Secondly, 24 rats were randomized in 3 groups as follows: sham, sham with an α7nAChR-antagonist and cervical vagotomy with an α7nAChR-antagonist. Finally, 24 rats were randomized in 3 groups as follows: fasting, high-fat nutrition before sham and high-fat nutrition before selective vagotomy. Abdominal (selective) vagotomy did not impact histopathological lung injury (LIS) compared with the control (sham) group (p > 0.999). There was a trend in aggravation of LIS after cervical vagotomy (p = 0.051), even after an α7nAChR-agonist (p = 0.090). Cervical vagotomy with an α7nAChR-antagonist aggravated lung injury (p = 0.004). Furthermore, cervical vagotomy increased macrophages in bronchoalveolar lavage (BAL) fluid and negatively impacted pulmonary function. Other inflammatory cells, TNF-α and IL-6, in the BALF and serum were unaffected. High-fat nutrition reduced LIS after sham (p = 0.012) and selective vagotomy (p = 0.002) compared to fasting. vagotomy. This study underlines the role of the vagus nerve in lung injury and shows that vagus nerve stimulation using high-fat nutrition is effective in reducing lung injury, even after selective vagotomy.

The role of age-associated autonomic dysfunction in inflammation and endothelial dysfunction

Aging of the cardiovascular regulatory function manifests as an imbalance between the sympathetic and parasympathetic (vagal) components of the autonomic nervous system (ANS). The most characteristic change is sympathetic overdrive, which is manifested by an increase in the muscle sympathetic nerve activity (MSNA) burst frequency with age. Age-related changes that occur in vagal nerve activity is less clear. The resting tonic parasympathetic activity can be estimated noninvasively by measuring the increase in heart rate occurring in response to muscarinic cholinergic receptor blockade; animal study models have shown this to diminish with age. Humoral, cellular, and neural mechanisms work together to prevent non-resolving inflammation. This review focuses on the mechanisms underlying age-related alternations in the ANS and how an imbalance in the ANS, evaluated by MSNA and heart rate variability (HRV), potentially facilitates inflammation when the homeostatic mechanisms between reflex neural circuits and the immune system are compromised, particularly the dysfunction of the cholinergic anti-inflammatory reflex. Physiologically, the efferent arm of this reflex acts via the [Formula: see text] 7 nicotinic acetylcholine receptors expressed in macrophages, monocytes, dendritic cells, T cells, and endothelial cells to curb the release of inflammatory cytokines, in which inhibition of NF‑κB nuclear translocation and activation of a JAK/STAT-mediated signaling cascade in macrophages and other immune cells are implicated. This reflex is likely to become less adequate with advanced age. Consequently, a pro-inflammatory state induced by reduced vagus output with age is associated with endothelial dysfunction and may significantly contribute to the development and propagation of atherosclerosis, heart failure, and hypertension. The aim of this review is to summarize the relationship between ANS dysfunction, inflammation, and endothelial dysfunction in the context of aging. Meanwhile, this review also attempts to describe the role of HRV measures as a predictor of the level of inflammation and endothelial dysfunction in the aged population and explore the possible therapeutical effects of vagus nerve stimulation.

Effects of Preserving the Pulmonary Vagus Nerve Branches on Cough After Pneumonectomy During Video-Assisted Thoracic Surgery

Background

Cough is one of the most common complications of early-stage non-small cell lung cancer (NSCLC) after video-assisted thoracoscopic surgery (VATS). The vagus nerve plays an important role in pulmonary inflammation and the cough reflex. In this study, we attempted to reduce the incidence of postoperative chronic cough and other complications by preserving the pulmonary vagus nerve branches.

Patients and Methods

This study was a randomized controlled double-blinded trial of subjects and observers. A total of 158 NSCLC patients were enrolled. We randomly assigned 79 patients to Group A (pulmonary branch of vagus nerve preservation group) and 79 cases to Group B (conventional surgical treatment group). In the final analysis, 72 patients from Group A and 69 patients from Group B were included. The main outcome measure of the study was the occurrence of CAP or other postoperative complications within five weeks. This trial was registered with ClinicalTrials.gov (number NCT03921828).

Results

There was no significant difference in preoperative general clinical data between the two groups. No death during the perioperative period occurred in either of the two groups. There was no significant difference between the two groups in operation time, intraoperative bleeding, number of lymph nodes sent for examination, number of cases transferred to ICU after operation, postoperative catheterization time, or postoperative hospital stay (P>0.05). There was no significant difference in other pulmonary and cardiovascular complications between the two groups, including pulmonary infection (2.78% vs. 8.70%, P = 0.129), atelectasis (1.39% vs. 0%, P = 0.326), pleural effusion (2.78% vs. 1.45%, P = 0.585), persistent pulmonary leakage (2.78% vs. 2.90%, P = 0.965), arrhythmia (2.78% vs. 1.45%, P = 0.585), and heart failure (0% vs. 1.45%, P = 0.305). The incidence of CAP in Group A was significantly lower than that in Group B (13.89% vs. 30.43%, P = 0.018). The LCQ-MC scores in Group A were significantly higher than those in Group B at two and five weeks after operation (P<0.05). Univariate and multivariate analysis showed that the risk factors for postoperative CAP were surgical side (right lung), surgical lung lobe (upper lobe), preservation of pulmonary branch of the vagus nerve during operation, and duration of anesthesia.

Conclusions

Preserving the pulmonary vagus nerve branches during VATS in patients with stage IA1-2 NSCLC can reduce the incidence of postoperative CAP.

Chemokine production induced by Corynebacterium pseudotuberculosis in a murine model

Corynebacterium pseudotuberculosis is the etiological agent of caseous lymphadenitis. The main clinical sign of this disease is the development of granulomas, especially in small ruminants; however, the pathways that are involved in the formation and maintenance of these granulomas are unknown. Cytokines and chemokines are responsible for the migration of immune cells to specific sites and tissues; therefore, it is possible that chemokines participate in abscess formation. This study aimed to evaluate the induction of chemokine production by two C. pseudotuberculosis strains in a murine model. A highly pathogenic (VD57) and an attenuated (T1) strain of C. pseudotuberculosis, as well as somatic and secreted antigens derived from these strains, was used to stimulate murine splenocytes. Then, the concentrations of the chemokines CCL-2, CCL-3, CCL-4, and CCL-5 and the cytokines IL-1 and TNF were measured in the culture supernatants. The VD57 strain had a higher ability to stimulate the production of chemokines when compared to T1 strain, especially in the early stages of stimulation, which can have an impact on granuloma formation. The T1 lysate antigen was able to stimulate most of the chemokines studied herein when compared to the other antigenic fractions of both strains. These results indicate that C. pseudotuberculosis is a chemokine production inducer, and the bacterial strains differ in their induction pattern, a situation that can be related to the specific behavior of each strain.

Protective Effects of a Rho Kinase Inhibitor on Paraquat-Induced Acute Lung Injuries in Rats

Fasudil, a rock kinase inhibitor, can inhibit systemic inflammation and prevent paraquat (PQ)-induced acute lung injuries in rats; however, the mechanisms for these protective effects remain elusive. This study investigated how the Rho/ROCK signaling pathway enables fasudil to protect against acute lung injuries in PQ-treated rats. Wistar rats (n = 240) were pretreated with fasudil (10 and 30 mg/kg, i.p.) 1 h prior to PQ administration. When compared to rats with PQ-induced lung injuries, rats pretreated with fasudil had significantly fewer polymorphonuclear neutrophils and lower concentrations of protein, TNF-α, IL-1β, and IL-6 in their bronchoalveolar lavage fluid. Moreover, fasudil also reduced the Evans Blue content, wet-to-dry weight ratio, lung injury scores, and levels malondialdehyde and 8-hydroxy-2 deoxyguanosine, but increased superoxide dismutase activity in lung tissue. Furthermore, Rho, ROCK1 expression and the levels of phosphorylated MYPT-1 in lung tissues were drastically decreased in fasudil-treated rats, whereas ZO-1 protein expression was significantly increased (p < 0.05). We found that fasudil downregulated bax and activated caspase-3 mRNA expression but upregulated Bcl-2 mRNA expression. In vitro experiments showed that the levels of TNF-α, IL-1β, and IL-6 secreted by human pulmonary microvascular endothelial cells treated with PQ were attenuated by fasudil. Fasudil inhibited the upregulation Rho and ROCK protein expression and downregulation of ZO-1 protein expression in HPMVECs induced with PQ. Higher concentrations of fasudil produced greater affects than lower concentrations. Fasudil improved endothelial permeability and inhibited inflammation, oxidative stress, and cell apoptosis to alleviate acute lung injuries in PQ-treated rats. Fasudil exerted these therapeutic effects by inhibiting the Rho/ROCK signaling pathway.

Vagal Modulation of the Inflammatory Response in Sepsis

The vagus nerve can sense peripheral inflammation and transmit action potentials from the periphery to the brainstem. Vagal afferent signaling is integrated in the brainstem, and efferent vagus nerves carry outbound signals that terminate in spleen and other organs. Stimulation of efferent vagus nerve leads to the release of acetylcholine in these organs. In turn, acetylcholine interacts with members of the nicotinic acetylcholine receptor (nAChR) family, particularly with the alpha7 nicotinic acetylcholine receptor (α7nAChR), which is expressed by macrophages and other cytokine-producing cells. Ultimately, the production of proinflammatory cytokines is markedly inhibited. This neuroimmune communication is termed "the inflammatory reflex". The uncontrolled inflammation as a result from sepsis can lead to multiple organ failure, and even death. Experimental data show that regulation of the inflammatory reflex appears to be a useful interventional strategy for septic response. Herein, we review recent advances in the understanding of the inflammatory reflex and discuss potential therapeutics that vagal modulation of the immune system for the treatment of severe sepsis and septic shock.

Chronic functional bowel syndrome enhances gut-brain axis dysfunction, neuroinflammation, cognitive impairment, and vulnerability to dementia

The irritable bowel syndrome (IBS) is a common chronic functional gastrointestinal disorder world wide that lasts for decades. The human gut harbors a diverse population of microbial organisms which is symbiotic and important for well being. However, studies on conventional, germ-free, and obese animals have shown that alteration in normal commensal gut microbiota and an increase in pathogenic microbiota-termed "dysbiosis", impact gut function, homeostasis, and health. Diarrhea, constipation, visceral hypersensitivity, and abdominal pain arise in IBS from the gut-induced dysfunctional metabolic, immune, and neuro-immune communication. Dysbiosis in IBS is associated with gut inflammation. Gut-related inflammation is pivotal in promoting endotoxemia, systemic inflammation, and neuroinflammation. A significant proportion of IBS patients chronically consume alcohol, non-steroidal anti-inflammatories, and fatty diet; they may also suffer from co-morbid respiratory, neuromuscular, psychological, sleep, and neurological disorders. The above pathophysiological substrate is underpinned by dysbiosis, and dysfunctional bidirectional "Gut-Brain Axis" pathways. Pathogenic gut microbiota-related systemic inflammation (due to increased lipopolysaccharide and pro-inflammatory cytokines, and barrier dysfunction), may trigger neuroinflammation enhancing dysfunctional brain regions including hippocampus and cerebellum. These as well as dysfunctional vago-vagal gut-brain axis may promote cognitive impairment. Indeed, inflammation is characteristic of a broad spectrum of neurodegenerative diseases that manifest demntia. It is argued that an awareness of pathophysiological impact of IBS and implementation of appropriate therapeutic measures may prevent cognitive impairment and minimize vulnerability to dementia.

Role of stress, depression, and aging in cognitive decline and Alzheimer's disease

Late-onset Alzheimer's disease (AD) is a chronic neurodegenerative disorder and the most common cause of progressive cognitive dysfunction and dementia. Despite considerable progress in elucidating the molecular pathology of this disease, we are not yet close to unraveling its etiopathogenesis. A battery of neurotoxic modifiers may underpin neurocognitive pathology via deleterious heterogeneous pathologic impact in brain regions, including the hippocampus. Three important neurotoxic factors being addressed here include aging, stress, and depression. Unraveling "upstream pathologies" due to these disparate neurotoxic entities, vis-à-vis cognitive impairment involving hippocampal dysfunction, is of paramount importance. Persistent systemic inflammation triggers and sustains neuroinflammation. The latter targets several brain regions including the hippocampus causing upregulation of amyloid beta and neurofibrillary tangles, synaptic and neuronal degeneration, gray matter volume atrophy, and progressive cognitive decline. However, what is the fundamental source of this peripheral inflammation in aging, stress, and depression? This chapter highlights and delineates the inflammatory involvement-i.e., from its inception from gut to systemic inflammation to neuroinflammation. It highlights an upregulated cascade in which gut-microbiota-related dysbiosis generates lipopolysaccharides (LPS), which enhances inflammation and gut's leakiness, and through a Web of interactions, it induces stress and depression. This may increase neuronal dysfunction and apoptosis, promote learning and memory impairment, and enhance vulnerability to cognitive decline.