Autonomic regulation of cellular immune function

Growth differentiation factor 15 alleviates diastolic dysfunction in mice with experimental diabetic cardiomyopathy

Growth differentiation factor 15 (GDF15) is a peptide with utility in obesity, as it decreases appetite and promotes weight loss. Because obesity increases the risk for type 2 diabetes (T2D) and cardiovascular disease, it is imperative to understand the cardiovascular actions of GDF15, especially since elevated GDF15 levels are an established biomarker for heart failure. As weight loss should be encouraged in the early stages of obesity-related prediabetes/T2D, where diabetic cardiomyopathy is often present, we assessed whether treatment with GDF15 influences its pathology. We observed that GDF15 treatment alleviates diastolic dysfunction in mice with T2D independent of weight loss. This cardioprotection was associated with a reduction in cardiac inflammation, which was likely mediated via indirect actions, as direct treatment of adult mouse cardiomyocytes and differentiated THP-1 human macrophages with GDF15 failed to alleviate lipopolysaccharide-induced inflammation. Therapeutic manipulation of GDF15 action may thus have utility for both obesity and diabetic cardiomyopathy.

Valsalva maneuver pressure recovery time is prolonged following spinal cord injury with correlations to autonomically-influenced secondary complications

PURPOSE

This work's purpose was to quantify rapid sympathetic activation in individuals with spinal cord injury (SCI), and to identify associated correlations with symptoms of orthostatic hypotension and common autonomically mediated secondary medical complications.

METHODS

This work was a cross-sectional study of individuals with SCI and uninjured individuals. Symptoms of orthostatic hypotension were recorded using the Composite Autonomic Symptom Score (COMPASS)-31 and Autonomic Dysfunction following SCI (ADFSCI) survey. Histories of secondary complications of SCI were gathered. Rapid sympathetic activation was assessed using pressure recovery time of Valsalva maneuver. Stepwise multiple linear regression models identified contributions to secondary medical complication burden.

RESULTS

In total, 48 individuals (24 with SCI, 24 uninjured) underwent testing, with symptoms of orthostatic hypotension higher in those with SCI (COMPASS-31, 3.3 versus 0.6, p < 0.01; ADFSCI, 21.2 versus. 3.2, p < 0.01). Pressure recovery time was prolonged after SCI (7.0 s versus. 1.7 s, p < 0.01), though poorly correlated with orthostatic symptom severity. Neurological level of injury after SCI influenced pressure recovery time, with higher injury levels associated with more prolonged time. Stepwise multiple linear regression models identified pressure recovery time as the primary explanation for variance in number of urinary tract infections (34%), histories of hospitalizations (12%), and cumulative secondary medical complication burden (24%). In all conditions except time for bowel program, pressure recovery time outperformed current clinical tools for assessing such risk.

CONCLUSIONS

SCI is associated with impaired rapid sympathetic activation, demonstrated here by prolonged pressure recovery time. Prolonged pressure recovery time after SCI predicts higher risk for autonomically mediated secondary complications, serving as a viable index for more "autonomically complete" injury.

What is the Vagal-Adrenal Axis?

Some recent publications have used the term "vagal-adrenal axis" to account for mechanisms involved in the regulation of inflammation by electroacupuncture. This concept proposes that efferent parasympathetic nerve fibers in the vagus directly innervate the adrenal glands to influence catecholamine secretion. Here, we discuss evidence for anatomical and functional links between the vagi and adrenal glands that may be relevant in the context of inflammation and its neural control by factors, including acupuncture. First, we find that evidence for any direct vagal parasympathetic efferent innervation of the adrenal glands is weak and likely artifactual. Second, we find good evidence that vagal afferent fibers directly innervate the adrenal gland, although their function is uncertain. Third, we highlight a wealth of evidence for indirect pathways, whereby vagal afferent signals act via the central nervous system to modify adrenal-dependent anti-inflammatory responses. Vagal afferents, not efferents, are thus the likely key to these phenomena.

Beta-adrenergic signaling and T-lymphocyte-produced catecholamines are necessary for interleukin 17A synthesis

Background

Post-traumatic stress disorder (PTSD) is a debilitating psychological disorder that also presents with neuroimmune irregularities. Patients display elevated sympathetic tone and are at an increased risk of developing secondary autoimmune diseases. Previously, using a preclinical model of PTSD, we demonstrated that elimination of sympathetic signaling to T-lymphocytes specifically limited their ability to produce pro-inflammatory interleukin 17A (IL-17A); a cytokine implicated in the development of many autoimmune disorders. However, the mechanism linking sympathetic signaling to T-lymphocyte IL-17A production remained unclear.

Methods

Using a modified version of repeated social defeat stress (RSDS) that allows for both males and females, we assessed the impact of adrenergic receptor blockade (genetically and pharmacologically) and catecholamine depletion on T-lymphocyte IL-17A generation. Additionally, we explored the impact of adrenergic signaling and T-lymphocyte-produced catecholamines on both CD4+ and CD8+ T-lymphocytes polarized to IL-17A-producing phenotypes ex vivo.

Results

Only pharmacological inhibition of the beta 1 and 2 adrenergic receptors (β1/2) significantly decreased circulating IL-17A levels after RSDS, but did not impact other pro-inflammatory cytokines (e.g., IL-6, TNF-α, and IL-10). This finding was confirmed using RSDS with both global β1/2 receptor knock-out mice, as well as by adoptively transferring β1/2 knock-out T-lymphocytes into immunodeficient hosts. Furthermore, ex vivo polarized T-lymphocytes produced significantly less IL-17A with the blockade of β1/2 signaling, even in the absence of exogenous sympathetic neurotransmitter supplementation, which suggested T-lymphocyte-produced catecholamines may be involved in IL-17A production. Indeed, pharmacological depletion of catecholamines both in vivo and ex vivo abrogated T-lymphocyte IL-17A production demonstrating the importance of immune-generated neurotransmission in pro-inflammatory cytokine generation.

Conclusions

Our data depict a novel role for β1/2 adrenergic receptors and autologous catecholamine signaling during T-lymphocyte IL-17A production. These findings provide a new target for pharmacological therapy in both psychiatric and autoimmune diseases associated with IL-17A-related pathology.

Psychosocial and behavioural predictors of immune response to influenza vaccination: a systematic review and meta-analysis

High variability of influenza vaccine efficacy requires the identification of modulators of immunisation that may be targeted as adjuvants in health psychology interventions. Psychosocial and behavioural variables such as psychological stress, greater negative and lower positive affectivity, poor sleep, loneliness, and lack of social support, have been associated with abnormal immune and inflammatory responses and negative health outcomes, yet their effects in modulating vaccine efficacy are yet to be fully understood. We conducted an updated systematic review of longitudinal and experimental studies examining the effects of such variables in predicting immune response to influenza vaccine. PubMed, Medline, PsycINFO, CINAHL and Scopus were searched up to November 2022. Twenty-five studies met the inclusion criteria for qualitative synthesis and 16 provided data for meta-analysis. Low positive and high negative affect were associated with low antibodies and weak cell-mediated immunity following vaccination in qualitative synthesis. Literature on sleep disturbance, loneliness and social support was limited and yielded inconsistent results. Psychological stress was associated with poorer antibody response in meta-analysis. In conclusion, findings from this review suggest a need for further longitudinal and experimental studies on these factors to support their inclusion as target variables in vaccine adjuvant interventions.

Pathological mechanisms of cold and mechanical stress in modulating cancer progression

Environmental temperature and cellular mechanical force are the inherent factors that participate in various biological processes and regulate cancer progress, which have been hot topics worldwide. They occupy a dominant part in the cancer tissues through different approaches. However, extensive investigation regarding pathological mechanisms in the carcinogenic field. After research, we found cold stress via two means to manipulate tumors: neuroscience and mechanically sensitive ion channels (MICHs) such as TRP families to regulate the physiological and pathological activities. Excessive cold stimulation mediated neuroscience acting on every cancer stage through the hypothalamus-pituitary-adrenocorticoid (HPA) to reach the target organs. Comparatively speaking, mechanical force via Piezo of MICHs controls cancer development. The progression of cancer depends on the internal activation of proto-oncogenes and the external tumorigenic factors; the above two means eventually lead to genetic disorders at the molecular level. This review summarizes the interaction of bidirectional communication between them and the tumor. It covers the main processes from cytoplasm to nucleus related to metastasis cascade and tumor immune escape.

Dominant mechanism in spinal cord injury-induced immunodeficiency syndrome (SCI-IDS): sympathetic hyperreflexia

Clinical studies have shown that individuals with spinal cord injury (SCI) are particularly susceptible to infectious diseases, resulting in a syndrome called SCI-induced immunodeficiency syndrome (SCI-IDS), which is the leading cause of death after SCI. It is believed that SCI-IDS is associated with exaggerated activation of sympathetic preganglionic neurons (SPNs). After SCI, disruption of bulbospinal projections from the medulla oblongata C1 neurons to the SPNs results in the loss of sympathetic inhibitory modulation from the brain and brainstem and the occurrence of abnormally high levels of spinal sympathetic reflexes (SSR), named sympathetic hyperreflexia. As the post-injury survival time lengthens, mass recruitment and anomalous sprouting of excitatory interneurons within the spinal cord result in increased SSR excitability, resulting in an excess sympathetic output that disrupts the immune response. Therefore, we first analyze the structural underpinnings of the spinal cord-sympathetic nervous system-immune system after SCI, then demonstrate the progress in highlighting mechanisms of SCI-IDS focusing on norepinephrine (NE)/Beta 2-adrenergic receptor (β2-AR) signal pathways, and summarize recent preclinical studies examining potential means such as regulating SSR and inhibiting β2-AR signal pathways to improve immune function after SCI. Finally, we present research perspectives such as to promote the effective regeneration of C1 neurons to rebuild the connection of C1 neurons with SPNs, to regulate excitable or inhibitory interneurons, and specifically to target β2-AR signal pathways to re-establish neuroimmune balance. These will help us design effective strategies to reverse post-SCI sympathetic hyperreflexia and improve the overall quality of life for individuals with SCI.

Therapeutic Use of Low-Dose Local Anesthetics in Pain, Inflammation, and Other Clinical Conditions: A Systematic Scoping Review

The use of low-dose local anesthetics (LAs) has significantly transformed patient care by providing rapid and effective relief of pain and other clinical conditions while minimizing recovery time. This study aims to identify and describe the existing scientific evidence on the therapeutic use of low-dose LAs in various conditions and to identify gaps in the current literature in order to prioritize future research. This systematic scoping review adhered to the methodological guidelines outlined in the Arksey and O'Malley framework, which includes five distinct stages. Of the 129 studies included, 37.98% (n = 49) were clinical trials, 55.03% (n = 71) were observational studies, and 6.97% (n = 9) were systematic reviews. The most commonly reported indication for the use of low-dose LAs was chronic pain management (72.86%), followed by acute pain management (13.17%). Additionally, non-pain-related indications were also identified (13.95%). Overall, the administration of low-dose, short-acting LAs demonstrated favorable outcomes in terms of pain management and reduction in anxiety and depression scales, thereby having a positive impact on the patients' quality of life. This review represents the first systematic scoping review regarding the therapeutic role of LAs. To substantiate the reported positive effects on efficacy and safety, further rigorous research comprising larger, well-designed randomized controlled trials (RCTs) and long-term outcome monitoring is imperative.

Depletion of Neural Crest-Derived Cells Leads to Plasma Noradrenaline Decrease and Alters T Cell Development

The differentiation of neural crest (NC) cells into various cell lineages contributes to the formation of many organs, including the thymus. In this study, we explored the role of NC cells in thymic T cell development. In double-transgenic mice expressing NC-specific Cre and the Cre-driven diphtheria toxin receptor, plasma noradrenaline and adrenaline levels were significantly reduced, as were thymic T cell progenitors, when NC-derived cells were ablated with short-term administration of diphtheria toxin. Additionally, yellow fluorescent protein+ NC-derived mesenchymal cells, perivascular cells, and tyrosine hydroxylase+ sympathetic nerves in the thymus significantly decreased. Furthermore, i.p. administration of 6-hydroxydopamine, a known neurotoxin for noradrenergic neurons, resulted in a significant decrease in thymic tyrosine hydroxylase+ nerves, a phenotype similar to that of depleted NC-derived cells, whereas administration of a noradrenaline precursor for ablating NC-derived cells or sympathetic nerves rarely rescued this phenotype. To clarify the role of NC-derived cells in the adult thymus, we transplanted thymus into the renal capsules of wild-type mice and observed abnormal T cell development in lethally irradiated thymus with ablation of NC-derived cells or sympathetic nerves, suggesting that NC-derived cells inside and outside of the thymus contribute to T cell development. In particular, the ablation of NC-derived mesenchymal cells in the thymus decreases the number of thymocytes and T cell progenitors. Overall, ablation of NC-derived cells, including sympathetic nerves, in the thymus leads to abnormal T cell development in part by lowering plasma noradrenalin levels. This study reveals that NC-derived cells including mesenchymal cells and sympathetic nerves within thymus regulate T cell development.

Vagus Nerve Stimulation and Inflammation in Cardiovascular Disease: A State-of-the-Art Review

Vagus nerve stimulation (VNS) has been found to exert anti-inflammatory effects in different clinical settings and has been associated with improvement of clinical outcomes. However, evidence on the mechanistic link between the potential association of inflammatory status with clinical outcomes following VNS is scarce. This review aims to summarize the existing knowledge linking VNS with inflammation and its potential link with major outcomes in cardiovascular diseases, in both preclinical and clinical studies. Existing data show that in the setting of myocardial ischemia and reperfusion, VNS seems to reduce inflammation resulting in reduced infarct size and reduced incidence of ventricular arrhythmias during reperfusion. Furthermore, VNS has a protective role in vascular function following myocardial ischemia and reperfusion. Atrial fibrillation burden has also been reduced by VNS, whereas suppression of inflammation may be a potential mechanism for this effect. In the setting of heart failure, VNS was found to improve systolic function and reverse cardiac remodeling. In summary, existing experimental data show a reduction in inflammatory markers by VNS, which may cause improved clinical outcomes in cardiovascular diseases. However, more data are needed to evaluate the association between the inflammatory status with the clinical outcomes following VNS.

Neuroanatomy of lymphoid organs: Lessons learned from whole-tissue imaging studies

Decades of extensive research have documented the presence of neural innervations of sensory, sympathetic, or parasympathetic origin in primary and secondary lymphoid organs. Such neural inputs can release neurotransmitters and neuropeptides to directly modulate the functions of various immune cells, which represents one of the essential aspects of the body's neuroimmune network. Notably, recent studies empowered by state-of-the-art imaging techniques have comprehensively assessed neural distribution patterns in BM, thymus, spleen, and LNs of rodents and humans, helping clarify several controversies lingering in the field. In addition, it has become evident that neural innervations in lymphoid organs are not static but undergo alterations in pathophysiological contexts. This review aims to update the current information on the neuroanatomy of lymphoid organs obtained through whole-tissue 3D imaging and genetic approaches, focusing on anatomical features that may designate the functional modulation of immune responses. Moreover, we discuss several critical questions that call for future research, which will advance our in-depth understanding of the importance and complexity of neural control of lymphoid organs.

Psychological distress influences lung cancer: Advances and perspectives on the immune system and immunotherapy

Lung cancer has the highest incidence rate and mortality worldwide. Moreover, multiple factors may cause heterogeneity in the efficacy of immunotherapy for lung cancer, and preclinical studies have gradually uncovered the promotive effects of psychological distress (PD) on tumor hallmarks. Therefore, treatment targeted at PD may be a vital factor in adjusting and improving immunotherapy for lung cancer. Here, by focusing on the central nervous system, as well as stress-related crucial neurotransmitters and hormones, we highlight the effects of PD on the lung immune system, the lung tumor microenvironment (TME) and immunotherapy, which brings a practicable means and psychosocial perspective to lung cancer treatment.

Modulation by luminal factors on the functions and migration of intestinal innate immunity

Luminal antigens, nutrients, metabolites from commensal bacteria, bile acids, or neuropeptides influence the function and trafficking of immune cells in the intestine. Among the immune cells in the gut, innate lymphoid cells, including macrophages, neutrophils, dendritic cells, mast cells, and innate lymphoid cells, play an important role for the maintenance of intestinal homeostasis through a rapid immune response to luminal pathogens. These innate cells are influenced by several luminal factors, possibly leading to dysregulated gut immunity and intestinal disorders such as inflammatory bowel disease (IBD), irritable bowel syndrome (IBS), and intestinal allergy. Luminal factors are sensed by distinct neuro-immune cell units, which also have a strong impact on immunoregulation of the gut. Immune cell trafficking from the blood stream through the lymphatic organ to lymphatics, an essential function for immune responses, is also modulated by luminal factors. This mini-review examines knowledge of luminal and neural factors that regulate and modulate response and migration of leukocytes including innate immune cells, some of which are clinically associated with pathological intestinal inflammation.

Peripheral Beta-2 Adrenergic Receptors Mediate the Sympathetic Efferent Activation from Central Nervous System to Splenocytes in a Mouse Model of Fibromyalgia

Abnormalities in the peripheral immune system are involved in the pathophysiology of fibromyalgia, although their contribution to the painful symptoms remains unknown. Our previous study reported the ability of splenocytes to develop pain-like behavior and an association between the central nervous system (CNS) and splenocytes. Since the spleen is directly innervated by sympathetic nerves, this study aimed to examine whether adrenergic receptors are necessary for pain development or maintenance using an acid saline-induced generalized pain (AcGP) model (an experimental model of fibromyalgia) and whether the activation of these receptors is also essential for pain reproduction by the adoptive transfer of AcGP splenocytes. The administration of selective β2-blockers, including one with only peripheral action, prevented the development but did not reverse the maintenance of pain-like behavior in acid saline-treated C57BL/6J mice. Neither a selective α1-blocker nor an anticholinergic drug affects the development of pain-like behavior. Furthermore, β2-blockade in donor AcGP mice eliminated pain reproduction in recipient mice injected with AcGP splenocytes. These results suggest that peripheral β2-adrenergic receptors play an important role in the efferent pathway from the CNS to splenocytes in pain development.

Sympathetic innervation of human and porcine spleens: implications for between species variation in function

BACKGROUND

The vagus nerve affects innate immune responses by activating spleen-projecting sympathetic neurons, which modulate leukocyte function. Recent basic and clinical research investigating vagus nerve stimulation to engage the cholinergic anti-inflammatory pathway (CAP) has shown promising therapeutic results for a variety of inflammatory diseases. Abundant sympathetic innervation occurs in rodent spleens, and use of these species has dominated mechanistic research investigating the CAP. However, previous neuroanatomical studies of human spleen found a more restricted pattern of innervation compared to rodents. Therefore, our primary goal was to establish the full extent of sympathetic innervation of human spleens using donor tissue with the shortest procurement to fixation time. Parallel studies of porcine spleen, a large animal model, were performed as a positive control and for comparison.

METHODS

Human and porcine spleen tissue were fixed immediately after harvest and prepared for immunohistochemistry. Human heart and porcine spleen were stained in conjunction as positive controls. Several immunohistochemical protocols were compared for best results. Tissue was stained for tyrosine hydroxylase (TH), a noradrenergic marker, using VIP purple chromogen. Consecutive tissue slices were stained for neuropeptide Y (NPY), which often co-localizes with TH, or double-labelled for TH and CD3, a T cell marker. High-magnification images and full scans of the tissue were obtained and analyzed for qualitative differences between species.

RESULTS

TH had dominant perivascular localization in human spleen, with negligible innervation of parenchyma, but such nerves were abundant throughout ventricular myocardium. In marked contrast, noradrenergic innervation was abundant in all regions of porcine spleen, with red pulp having more nerves than white pulp. NPY stain results were consistent with this pattern. In human spleen, noradrenergic nerves only ran close to T cells at the boundary of the periarterial lymphatic sheath and arteries. In porcine spleen, noradrenergic nerves were closely associated with T cells in both white and red pulp as well as other leukocytes in red pulp.

CONCLUSION

Sympathetic innervation of the spleen varies between species in both distribution and abundance, with humans and pigs being at opposite extremes. This has important implications for sympathetic regulation of neuroimmune interactions in the spleen of different species and focused targeting of the CAP in humans.

Effects of α and β-adrenergic signaling on innate immunity and Porphyromonas gingivalis virulence in an invertebrate model

To investigate the role of adrenergic signalling (AS) in the host immune response and Porphyromonas gingivalis virulence, we compared norepinephrine (NE) and isoproterenol (ISO) responses in Galleria mellonella. P. gingivalis infection was evaluated by survival; humoral immune responses (i.e. melanization and cecropin and gloverin mRNA expression); cellular immune responses (i.e. haemocyte count, nodulation by histology); and P. gingivalis recovery (CFU/mL). P. gingivalis was cultivated in the presence of ISO (PgISO) or NE and injected into the larvae for survival evaluation. Finally, we co-injected ISO and PgISO to evaluate the concomitant effects on the immune response and bacterial virulence. None of the ligands were toxic to the larvae; ISO increased haemocyte number, even after P. gingivalis infection, by mobilizing sessile haemocytes in a β-adrenergic-specific manner, while NE showed the opposite effect. ISO treatment reduced larval mortality and the number of recovered bacteria, while NE increased mortality and showed no effect on bacterial recovery. ISO and NE had similar effects on melanization and decreased the expression of cecropin. Although co-cultivation with NE and ISO increased the gene expression of bacterial virulence factors in vitro, only the injection of PgISO increased larval death, which was partially reversed by circulating ISO. Therefore, α- and β-adrenergic signalling had opposite effects after P. gingivalis infection. Ultimately, the catecholamine influence on the immune response overcame the effect of more virulent strains. The effect of AS directly on the pathogen found in vitro did not translate to the in vivo setting.

Divergent splanchnic sympathetic efferent nerve pathways regulate interleukin-10 and tumour necrosis factor-α responses to endotoxaemia

The efferent branches of the splanchnic sympathetic nerves that enhance interleukin-10 (IL-10) and suppress tumour necrosis factor-α (TNF) levels in the reflex response to systemic immune challenge were investigated in anaesthetized, ventilated rats. Plasma levels of TNF and IL-10 were measured 90 min after intravenous lipopolysaccharide (LPS, 60 µg/kg). Splanchnic nerve section, ganglionic blockade with pentolinium tartrate or β₂ adrenoreceptor antagonism with ICI 118551 all blocked IL-10 responses. Restoring plasma adrenaline after splanchnic denervation rescued IL-10 responses. TNF responses were disinhibited by splanchnic denervation or pentolinium treatment, but not by ICI 118551. Splanchnic nerve branches were cut individually or in combination in vagotomized rats, ruling out any vagal influence on results. Distal splanchnic denervation, sparing the adrenal nerves, disinhibited TNF but did not reduce IL-10 responses. Selective adrenal denervation depressed IL-10 but did not disinhibit TNF responses. Selective denervation of either spleen or liver did not affect IL-10 or TNF responses, but combined splenic and adrenal denervation did so. Finally, combined section of the cervical and lumbar sympathetic nerves did not affect cytokine responses to LPS. Together, these results show that the endogenous anti-inflammatory reflex is mediated by sympathetic efferent fibres that run in the splanchnic, but not other sympathetic nerves, nor the vagus. Within the splanchnic nerves, divergent pathways control these two cytokine responses: neurally driven adrenaline, acting via β₂ adrenoreceptors, regulates IL-10, while TNF is restrained by sympathetic nerves to abdominal organs including the spleen, where non-β₂ adrenoreceptor mechanisms are dominant. KEY POINTS: An endogenous neural reflex, mediated by the splanchnic, but not other sympathetic nerves, moderates the cytokine response to systemic inflammatory challenge. This reflex suppresses the pro-inflammatory cytokine tumour necrosis factor-α (TNF), while enhancing levels of the anti-inflammatory cytokine interleukin-10 (IL-10). The reflex enhancement of IL-10 depends on the splanchnic nerve supply to the adrenal gland and on β₂ adrenoreceptors, consistent with mediation by circulating adrenaline. After splanchnic nerve section it can be rescued by restoring circulating adrenaline. The reflex suppression of TNF depends on splanchnic nerve branches that innervate abdominal tissues including, but not restricted to, spleen: it is not blocked by adrenal denervation or β₂ adrenoreceptor antagonism. Distinct sympathetic efferent pathways are thus responsible for pro- and anti-inflammatory cytokine components of the reflex regulating inflammation.

Dissecting the role of cell signaling versus CD8+ T cell modulation in propranolol antitumor activity

Preclinical and early clinical mechanistic studies of antitumor activity from the beta-adrenergic receptor (β-AR) blocker propranolol have revealed both cell signaling and immune function pathway effects. Intertumoral studies were performed using propranolol, a β₁-AR selective agent (atenolol), and a β₂-AR selective agent (ICI 118,551) in a preclinical in vivo model, as a step to dissect the contribution of cell signaling and CD8⁺ immunological effects on anticancer activity. We found that repression of β₂-AR but not β₁-AR signaling selectively suppressed cell viability and inhibited xenograft growth in vivo. Moreover, western blot analysis indicated that the phosphorylation levels of AKT/MEK/ERK were significantly decreased following the inhibition of β₂-AR. Furthermore, propranolol was found to activate the tumor microenvironment by inducing an increased intratumoral frequency of CD8⁺ T cells, whereas neither selective β₁ nor β₂-AR blockers had a significant effect on the tumor immune microenvironment. Thus, the results of this mechanistic dissection support a predominant role of tumor cell signaling, rather than the accumulation of CD8⁺ T cells, as the basis for propranolol antitumor activity. KEY MESSAGES : Molecular signaling of AKT/MAPK pathway contributes to propranolol caused cancer control. CD8+ T cells in tumor microenvironment were activated upon propranolol exposure. The basis for propranolol antitumor activity was predominantly dependent on cell signaling, rather than the activation of CD8+ T cells.

A Sedentary and Unhealthy Lifestyle Fuels Chronic Disease Progression by Changing Interstitial Cell Behaviour: A Network Analysis

Managing chronic diseases, such as heart disease, stroke, diabetes, chronic lung disease and Alzheimer’s disease, account for a large proportion of health care spending, yet they remain in the top causes of premature mortality and are preventable. It is currently accepted that an unhealthy lifestyle fosters a state of chronic low-grade inflammation that is linked to chronic disease progression. Although this is known to be related to inflammatory cytokines, how an unhealthy lifestyle causes cytokine release and how that in turn leads to chronic disease progression are not well known. This article presents a theory that an unhealthy lifestyle fosters chronic disease by changing interstitial cell behavior and is supported by a six-level hierarchical network analysis. The top three networks include the macroenvironment, social and cultural factors, and lifestyle itself. The fourth network includes the immune, autonomic and neuroendocrine systems and how they interact with lifestyle factors and with each other. The fifth network identifies the effects these systems have on the microenvironment and two types of interstitial cells: macrophages and fibroblasts. Depending on their behaviour, these cells can either help maintain and restore normal function or foster chronic disease progression. When macrophages and fibroblasts dysregulate, it leads to chronic low-grade inflammation, fibrosis, and eventually damage to parenchymal (organ-specific) cells. The sixth network considers how macrophages change phenotype. Thus, a pathway is identified through this hierarchical network to reveal how external factors and lifestyle affect interstitial cell behaviour. This theory can be tested and it needs to be tested because, if correct, it has profound implications. Not only does this theory explain how chronic low-grade inflammation causes chronic disease progression, it also provides insight into salutogenesis, or the process by which health is maintained and restored. Understanding low-grade inflammation as a stalled healing process offers a new strategy for chronic disease management. Rather than treating each chronic disease separately by a focus on parenchymal pathology, a salutogenic strategy of optimizing interstitial health could prevent and mitigate multiple chronic diseases simultaneously.

Neuronal-Immune Cell Units in Allergic Inflammation in the Nose

Immune cells and immune-derived molecules, endocrine glands and hormones, the nervous system and neuro molecules form the combined tridirectional neuroimmune network, which plays a significant role in the communication pathways and regulation at the level of the whole organism and local levels, in both healthy persons and patients with allergic rhinitis based on an allergic inflammatory process. This review focuses on a new research paradigm devoted to neuronal-immune cell units, which are involved in allergic inflammation in the nose and neuroimmune control of the nasal mucociliary immunologically active epithelial barrier. The categorization, cellular sources of neurotransmitters and neuropeptides, and their prevalent profiles in constituting allergen tolerance maintenance or its breakdown are discussed. Novel data on the functional structure of the nasal epithelium based on a transcriptomic technology, single-cell RNA-sequencing results, are considered in terms of neuroimmune regulation. Notably, the research of pathogenesis and therapy for atopic allergic diseases, including recently identified local forms, from the viewpoint of the tridirectional interaction of the neuroimmune network and discrete neuronal-immune cell units is at the cutting-edge.

The Role of β-Adrenergic Receptors in the Regulation of the Functions of Innate Immune Cells during Cold Stress In Vivo

It was found that 10-min cold stress enhanced stimulated production of ROS, while 60-min cold stress increased both spontaneous and stimulated ROS production by peritoneal macrophages. β-Adrenergic receptor blockade leveled the effect of 10-min stress in stimulated cultures and the effect of 60-min stress in spontaneous cultures. None variants of cold stress affected spontaneous and stimulated production of IL-1β. We observed an increase in the production of IL-1β in stimulated cultures from animals subjected to 10- and 60-min stress against the background of propranolol. At the same time, both variants of cold exposure, irrespective of β-adrenergic receptor blockade, stimulated IL-10 synthesis in spontaneous and activated samples. None of the used models of cold exposure affected the phagocytic activity of peritoneal macrophages. Thus, β-adrenergic receptors are directly involved in the regulation of cytokine production and microbicidal potential of macrophages in acute cold stress.

A Hypothesis Regarding Neurosecretory Inhibition of Stress Mediators by Colchicine in Preventing Stress-Induced Familial Mediterranean Fever Attacks

Familial Mediterranean fever (FMF) is a monogenic autoinflammatory disease characterized by recurrent episodes of fever and serositis. Colchicine (Col) has a crucial role in the prevention of amyloidosis and FMF attacks. The effect of Col on innate immune cells is based on the inhibition of the microtubule system. The microtubule system is also very important for neurosecretory functions. The inhibitory effect of Col on neurosecretory functions is an overlooked issue. Considering that the neuroimmune cross-talk process plays a role in the development of inflammatory diseases, the effect of Col on the neuronal system becomes important. FMF attacks are related to emotional stress. Therefore, the effect of Col on stress mediators is taken into consideration. In this hypothetical review, we discuss the possible effects of Col on the central nervous systems (CNS) and peripheral nervous systems (PNS) in light of mostly experimental study findings using animal models. Studies to be carried out on this subject will shed light on the pathogenesis of FMF attacks and the other possible mechanisms of action of Col apart from the anti-inflammatory features.

Neuroimmune Interactions in Peripheral Organs

Interactions between the nervous and immune systems were recognized long ago, but recent studies show that this crosstalk occurs more frequently than was previously appreciated. Moreover, technological advances have enabled the identification of the molecular mediators and receptors that enable the interaction between these two complex systems and provide new insights on the role of neuroimmune crosstalk in organismal physiology. Most neuroimmune interaction occurs at discrete anatomical locations in which neurons and immune cells colocalize. Here, we describe the interactions of the different branches of the peripheral nervous system with immune cells in various organs, including the skin, intestine, lung, and adipose tissue. We highlight how neuroimmune crosstalk orchestrates physiological processes such as host defense, tissue repair, metabolism, and thermogenesis. Unraveling these intricate relationships is invaluable to explore the therapeutic potential of neuroimmune interaction. Expected final online publication date for the Annual Review of Neuroscience, Volume 45 is July 2022. Please see http://www.annualreviews.org/page/journal/pubdates for revised estimates.

The Association between Inflammatory Biomarkers and Cardiovascular Autonomic Dysfunction after Bacterial Infection

Heart rate variability (HRV) is a known measure of cardiac autonomic function. A cardiovascular autonomic dysfunction (CAD), measured as changes in HRV, is usually presented after an infectious process. The aim of the present study is to assess the association between serum inflammatory markers and CAD. For this purpose, 50 volunteers (13 of them recovering from an infection) were recruited and followed-up for 6 weeks. Their serum inflammatory biomarkers (CRP, IL1, IL4, IL6, IL10, and TNFalpha) were quantified throughout those weeks, along with their HRV resting, in response to the Valsalva maneuver, metronome breathing, standing and sustained handgrip. The correlation of within-subject changes in both HRV and inflammatory biomarkers was assessed to evaluate the concurrent changes. An inverse within-subject correlation was found between CRP and HRV in response to the Valsalva maneuver (rho (95% CI): −0.517 (−0.877 to −0.001); p = 0.032) and HRV standing (rho (95% CI): −0.490 (−0.943 to −0.036); p = 0.034). At the beginning, increased values of CRP are found along with reduced levels of HRV. Then, the CRP was reduced, accompanied by an improvement (increase) in HRV. These results suggest that CRP is a potential marker of CAD. Whether it is the cause, the consequence or a risk indicator non-causally associated is still to be determined.

Inflammation and Cardiovascular Diseases in the Elderly: The Role of Epicardial Adipose Tissue

Human aging is a complex phenomenon characterized by a wide spectrum of biological changes which impact on behavioral and social aspects. Age-related changes are accompanied by a decline in biological function and increased vulnerability leading to frailty, thereby advanced age is identified among the major risk factors of the main chronic human diseases. Aging is characterized by a state of chronic low-grade inflammation, also referred as inflammaging. It recognizes a multifactorial pathogenesis with a prominent role of the innate immune system activation, resulting in tissue degeneration and contributing to adverse outcomes. It is widely recognized that inflammation plays a central role in the development and progression of numerous chronic and cardiovascular diseases. In particular, low-grade inflammation, through an increased risk of atherosclerosis and insulin resistance, promote cardiovascular diseases in the elderly. Low-grade inflammation is also promoted by visceral adiposity, whose accumulation is paralleled by an increased inflammatory status. Aging is associated to increase in epicardial adipose tissue (EAT), the visceral fat depot of the heart. Structural and functional changes in EAT have been shown to be associated with several heart diseases, including coronary artery disease, aortic stenosis, atrial fibrillation, and heart failure. EAT increase is associated with a greater production and secretion of pro-inflammatory mediators and neuro-hormones, so that thickened EAT can pathologically influence, in a paracrine and vasocrine manner, the structure and function of the heart and is associated to a worse cardiovascular outcome. In this review, we will discuss the evidence underlying the interplay between inflammaging, EAT accumulation and cardiovascular diseases. We will examine and discuss the importance of EAT quantification, its characteristics and changes with age and its clinical implication.

Surgical stress quickly affects the numbers of circulating B-cells and neutrophils in murine septic and aseptic models through a β2 adrenergic receptor

Sepsis is a pathology accompanied by increases in myeloid cells and decreases in lymphoid cells in circulation. In a murine sepsis model induced by cecum ligation and puncture (CLP), increasing numbers of neutrophils and decreasing levels of B-cells in circulation are among the earliest changes in the immune system. However, to date, the mechanisms for these changes remain to be elucidated. The study here sought to elucidate mechanisms underlying the changes in the leukocyte levels after CLP and also to determine what, if any, role for an involvement of the sympathetic nervous system (SNS). Here, male C57/BL6 mice were subjected to CLP or sham-CLP (abdominal wall incised, but cecum was not punctured). The changes in the number of circulating leukocytes over time were then investigated using flow cytometry. The results showed that a sham-CLP led to increased polymorphonuclear cells (PMN; most of which are neutrophils) and decreased B-cells in the circulation to an extent similar to that induced by CLP. Effects of adrenergic agonists and antagonists, as well as of adrenalectomy, were also examined in mice that underwent CLP or sham-CLP. Administering adrenaline or a β₂ adrenergic receptor agonist (clenbuterol) to mice 3 h before sacrifice produced almost identical changes to as what was seen 2 h after performing a sham-CLP. In contrast, giving a β₂ adrenergic receptor antagonist ICI118,551 1 h before a CLP or sham-CLP suppressed the expected changes 2 h after the operations. Noradrenaline and an α1 adrenergic receptor agonist phenylephrine did not exert significant effects. Adrenalectomy 24 h before a sham-CLP significantly abolished the expected sham-CLP-induced changes seen earlier. Clenbuterol increased splenocyte expression of Cxcr4 (a chemokine receptor gene); adrenalectomy abolished sham-CLP-induced Cxcr4 expression. A CXCR4 antagonist AMD3100 repressed the sham-CLP-induced changes. From these results, it may be concluded that sepsis-induced activation of the SNS may be one cause for immune dysfunction in sepsis - regardless of the pathogenetic processes.

17β-Estradiol Concentration and Direct β2-Adrenoceptor Inhibition Determine Estrogen-Mediated Reversal of Adrenergic Immunosuppression

Background:

Sympathetic innervation of lymphoid organs, and the presence of 17β-estradiol (estrogen or E2) and adrenergic receptors (ARs) on lymphocytes, suggests that sympathetic stimulation and hormonal activation may influence immune functions.

Purpose:

Modeling and simulating these pathways may help to understand the dynamics of neuroendocrine-immune modulation at the cellular and molecular levels.

Methods:

Dose- and receptor-dependent effects of E2 and AR subtype-specific agonists were established in vitro on lymphocytes from young male Sprague-Dawley rats and were modeled in silico using the MATLAB Simbiology toolbox. Kinetic principles were assigned to define receptor–ligand dynamics, and concentration/time plots were obtained using Ode15s solvers at different time intervals for key regulatory molecules. Comparisons were drawn between in silico and in vitro data for validating the constructed model with sensitivity analysis of key regulatory molecules to assess their individual impacts on the dynamics of the system. Finally, docking studies were conducted with key ligands E2 and norepinephrine (NE) to understand the mechanistic principles underlying their interactions.

Results:

Adrenergic activation triggered proapoptotic signals, while E2 enhanced survival signals, showing opposing effects as observed in vitro. Treatment of lymphocytes with E2 shows a 10-fold increase in survival signals in a dose-dependent manner. Cyclic adenosine monophosphate (cAMP) activation is crucial for the activation of survival signals through extracellular signal-regulated kinase (p-ERK) and cAMP responsive element binding (p-CREB) protein. Docking studies showed the direct inhibition of ERK by NE and β2-AR by E2 explaining how estrogen signaling overrides NE-mediated immunosuppression in vitro.

Conclusion:

The cross-talk between E2 and adrenergic signaling pathways determines lymphocyte functions in a receptor subtype and coactivation-dependent manner in health and disease.

Role of autonomic system imbalance in neurogenic pulmonary oedema

Neurogenic pulmonary oedema (NPE) is a life-threatening complication that develops rapidly and dramatically after an injury to the central nervous system (CNS). The autonomic system imbalance produced by severe brain damage may play an important role in the development of NPE. Activation of the sympathetic nervous system and inhibition of the vagus nerve system are essential prerequisites for autonomic system imbalance. The more severe the damage, the more pronounced the phenomenon. Sympathetic hyperactivity is associated with increased release of catecholamines from peripheral sympathetic nerve endings, which can cause dramatic changes in haemodynamics and cause pulmonary oedema. On the other hand, the abnormal inflammatory response caused by vagus nerve inhibition may also play an important role in the pathogenesis of NPE. The perspective of autonomic system imbalance seems to perfectly integrate the existing pathogenesis of NPE and can explain the entire development progression of NPE.

The Interplay between Autonomic Nervous System and Inflammation across Systemic Autoimmune Diseases

The autonomic nervous system (ANS) and the immune system are deeply interrelated. The ANS regulates both innate and adaptive immunity through the sympathetic and parasympathetic branches, and an imbalance in this system can determine an altered inflammatory response as typically observed in chronic conditions such as systemic autoimmune diseases. Rheumatoid arthritis, systemic lupus erythematosus, and systemic sclerosis all show a dysfunction of the ANS that is mutually related to the increase in inflammation and cardiovascular risk. Moreover, an interaction between ANS and the gut microbiota has direct effects on inflammation homeostasis. Recently vagal stimulation techniques have emerged as an unprecedented possibility to reduce ANS dysfunction, especially in chronic diseases characterized by pain and a decreased quality of life as well as in chronic inflammation.

Sympathetic Nerves and Innate Immune System in the Spleen: Implications of Impairment in HIV-1 and Relevant Models

The immune and sympathetic nervous systems are major targets of human, murine and simian immunodeficiency viruses (HIV-1, MAIDS, and SIV, respectively). The spleen is a major reservoir for these retroviruses, providing a sanctuary for persistent infection of myeloid cells in the white and red pulps. This is despite the fact that circulating HIV-1 levels remain undetectable in infected patients receiving combined antiretroviral therapy. These viruses sequester in immune organs, preventing effective cures. The spleen remains understudied in its role in HIV-1 pathogenesis, despite it hosting a quarter of the body’s lymphocytes and diverse macrophage populations targeted by HIV-1. HIV-1 infection reduces the white pulp, and induces perivascular hyalinization, vascular dysfunction, tissue infarction, and chronic inflammation characterized by activated epithelial-like macrophages. LP-BM5, the retrovirus that induces MAIDS, is a well-established model of AIDS. Immune pathology in MAIDs is similar to SIV and HIV-1 infection. As in SIV and HIV, MAIDS markedly changes splenic architecture, and causes sympathetic dysfunction, contributing to inflammation and immune dysfunction. In MAIDs, SIV, and HIV, the viruses commandeer splenic macrophages for their replication, and shift macrophages to an M2 phenotype. Additionally, in plasmacytoid dendritic cells, HIV-1 blocks sympathetic augmentation of interferon-β (IFN-β) transcription, which promotes viral replication. Here, we review viral–sympathetic interactions in innate immunity and pathophysiology in the spleen in HIV-1 and relevant models. The situation remains that research in this area is still sparse and original hypotheses proposed largely remain unanswered.

Effects of Exercise Training on the Autonomic Nervous System with a Focus on Anti-Inflammatory and Antioxidants Effects

Studies show that the autonomic nervous system (ANS) has an important impact on health in general. In response to environmental demands, homeostatic processes are often compromised, therefore determining an increase in the sympathetic nervous system (SNS)’s functions and a decrease in the parasympathetic nervous system (PNS)’s functions. In modern societies, chronic stress associated with an unhealthy lifestyle contributes to ANS dysfunction. In this review, we provide a brief introduction to the ANS network, its connections to the HPA axis and its stress responses and give an overview of the critical implications of ANS in health and disease—focused specifically on the immune system, cardiovascular, oxidative stress and metabolic dysregulation. The hypothalamic–pituitary–adrenal axis (HPA), the SNS and more recently the PNS have been identified as regulating the immune system. The HPA axis and PNS have anti-inflammatory effects and the SNS has been shown to have both pro- and anti-inflammatory effects. The positive impact of physical exercise (PE) is well known and has been studied by many researchers, but its negative impact has been less studied. Depending on the type, duration and individual characteristics of the person doing the exercise (age, gender, disease status, etc.), PE can be considered a physiological stressor. The negative impact of PE seems to be connected with the oxidative stress induced by effort.

The Influence of Modern Neurophysiology on the Previous Definitions of "Segment" and "Interference Field" in Neural Therapy

BACKGROUND

In neural therapy, local anesthetics are injected for diagnostic and therapeutic purposes. Up until now, a distinction has been made between "local/segmental neural therapy" and "interference field therapy". This division dating back to the middle of the last century was based on the assumption that anatomical and clinical segments were identical. However, this is only true for the projection symptoms, which are limited to metamerism. All pathophysiological processes beyond this segment were called "interference field events" ("outside of any segmental order" and "not explainable by neuroanatomical circuitry").

SUMMARY

However, modern neurophysiology no longer recognizes segmental boundaries, taking into account the occurrence of cross-segmental sensitization processes, neuroplastic changes, immune processes, and neurogenic inflammation. In addition, new insights into neuroanatomical circuitry have also contributed to segmental expansion. Thus, the former definition of the interference field effect (considered to be outside any segmental order) is considered obsolete. Nowadays, interference fields are called "neuromodulatory triggers". They can act anywhere, both locally and fairly distant, and even systemically. Key Message: Thus, it is no longer tenable to classify interference field therapy as "unscientific" and "not recognized" while local and segmental neural therapy is being scientifically recognized.

Reflex regulation of systemic inflammation by the autonomic nervous system

This short review focusses on the inflammatory reflex, which acts in negative feedback manner to moderate the inflammatory consequences of systemic microbial challenge. The historical development of the inflammatory reflex concept is reviewed, along with evidence that the endogenous reflex response to systemic inflammation is mediated by the splanchnic sympathetic nerves rather than by the vagi. We describe the coordinated nature of this reflex anti-inflammatory action: suppression of pro-inflammatory cytokines coupled with enhanced levels of the anti-inflammatory cytokine, interleukin 10. The limited information on the afferent and central pathways of the reflex is noted. We describe that the efferent anti-inflammatory action of the reflex is distributed among the abdominal viscera: several organs, including the spleen, can be removed without disabling the reflex. Understanding of the effector mechanism is incomplete, but it probably involves a very local action of neurally released noradrenaline on beta₂ adrenoceptors on the surface of tissue resident macrophages and other innate immune cells. Finally we speculate on the biological and clinical significance of the reflex, citing evidence of its power to influence the resolution of experimental bacteraemia.

Immunity and pain in the eye: focus on the ocular surface

Most ocular diseases are associated with pain. While pain has been generally considered a mere (deleterious) additional symptom, it is now emerging that it is a key modulator of innate/adaptive immunity. Because the cornea receives the highest nerve density of the entire body, it is an ideal site to demonstrate interactions between pain and the immune response. Indeed, most neuropeptides involved in pain generation are also potent regulators of innate and adaptive leukocyte physiology. On the other hand, most inflammatory cells can modulate the generation of ocular pain through release of specific mediators (cytokines, chemokines, growth factors, and lipid mediators). This review will discuss the reciprocal role(s) of ocular surface (and specifically: corneal) pain on the immune response of the eye. Finally, we will discuss the clinical implications of such reciprocal interactions in the context of highly prevalent corneal diseases.

Regulation of acute reflectory hyperinflammation in viral and other diseases by means of stellate ganglion block. A conceptual view with a focus on Covid-19

Whereas the autonomic nervous system (ANS) and the immune system used to be assigned separate functions, it has now become clear that the ANS and the immune system (and thereby inflammatory cascades) work closely together. During an acute immune response (e. g., in viral infection like Covid-19) the ANS and the immune system establish a fast interaction resulting in "physiological" inflammation. Based on our knowledge of the modulation of inflammation by the ANS we propose that a reflectory malfunction of the ANS with hyperactivity of the sympathetic nervous system (SNS) may be involved in the generation of acute hyperinflammation. We believe that sympathetic hyperactivity triggers a hyperresponsiveness of the immune system ("cytokine storm") with consecutive tissue damage. These reflectory neuroimmunological and inflammatory cascades constitute a general reaction principle of the organism under the leadership of the ANS and does not only occur in viral infections, although Covid-19 is a typical current example therefore. Within the overreaction several interdependent pathological positive feedback loops can be detected in which the SNS plays an important part. Consequently, there is a chance to regulate the hyperinflammation by influencing the SNS. This can be achieved by a stellate ganglion block (SGB) with local anesthetics, temporarily disrupting the pathological positive feedback loops. Thereafter, the complex neuroimmune system has the chance to reorganize itself. Previous clinical and experimental data have confirmed a favorable outcome in hyperinflammation (including pneumonia) after SGB (measurable e. g. by a reduction in proinflammatory cytokines).

The Regulation Effect of α7nAChRs and M1AChRs on Inflammation and Immunity in Sepsis

The inflammatory storm in the early stage and immunosuppression in the late stage are responsible for the high mortality rates and multiple organ dysfunction in sepsis. In recent years, studies have found that the body's cholinergic system can spontaneously and dynamically regulate inflammation and immunity in sepsis according to the needs of the body. Firstly, the vagus nerve senses and regulates local or systemic inflammation by means of the Cholinergic Anti-inflammatory Pathway (CAP) and activation of α7-nicotinic acetylcholine receptors (α7nAChRs); thus, α7nAChRs play important roles for the central nervous system (CNS) to modulate peripheral inflammation; secondly, the activation of muscarinic acetylcholine receptors 1 (M1AChRs) in the forebrain can affect the neurons of the Medullary Visceral Zone (MVZ), the core of CAP, to regulate systemic inflammation and immunity. Based on the critical role of these two cholinergic receptor systems in sepsis, it is necessary to collect and analyze the related findings in recent years to provide ideas for further research studies and clinical applications. By consulting the related literature, we draw some conclusions: MVZ is the primary center for the nervous system to regulate inflammation and immunity. It coordinates not only the sympathetic system and vagus system but also the autonomic nervous system and neuroendocrine system to regulate inflammation and immunity; α7nAChRs are widely expressed in immune cells, neurons, and muscle cells; the activation of α7nAChRs can suppress local and systemic inflammation; the expression of α7nAChRs represents the acute or chronic inflammatory state to a certain extent; M1AChRs are mainly expressed in the advanced centers of the brain and regulate systemic inflammation; neuroinflammation of the MVZ, hypothalamus, and forebrain induced by sepsis not only leads to their dysfunctions but also underlies the regulatory dysfunction on systemic inflammation and immunity. Correcting the neuroinflammation of these regulatory centers and adjusting the function of α7nAChRs and M1AChRs may be two key strategies for the treatment of sepsis in the future.

The sympathies of the body: functional organization and neuronal differentiation in the peripheral sympathetic nervous system

During the last 30 years, our understanding of the development and diversification of postganglionic sympathetic neurons has dramatically increased. In parallel, the list of target structures has been critically extended from the cardiovascular system and selected glandular structures to metabolically relevant tissues such as white and brown adipose tissue, lymphoid tissues, bone, and bone marrow. A critical question now emerges for the integration of the diverse sympathetic neuron classes into neural circuits specific for these different target tissues to achieve the homeostatic regulation of the physiological ends affected.

Cancer as a homeostatic challenge: the role of the hypothalamus

The initiation, progression, and metastatic spread of cancer elicits diverse changes in systemic physiology. In this way, cancer represents a novel homeostatic challenge to the host system. Here, we discuss how the hypothalamus, a critical brain region involved in homeostasis senses, integrates and responds to cancer-induced changes in physiology. Through this lens, cancer-associated changes in behavior (e.g., sleep disruption) and physiology (e.g., glucocorticoid dysregulation) can be viewed as the result of an inability to re-establish homeostasis. We provide examples at each level (receptor sensing, integration of systemic signals, and efferent regulatory pathways) of how homeostatic organization becomes disrupted across different cancers. Finally, we lay out predictions of this hypothesis and highlight outstanding questions that aim to guide further work in this area.

Inhaled Beta2-Agonists Increase In-Hospital Mortality in ICU Patients with Heart Failure

The impact of beta2-agonists (B2As) on heart failure (HF) remains controversial. This study aimed to investigate whether inhaled B2As increased in-hospital mortality in ICU patients with HF.The Multiparameter Intelligent Monitoring in Intensive Care III database was initially searched to identify adult patients (≥ 18 years old) with HF in ICU. Then, patients using or not using inhaled B2As were matched using propensity score matching on a 1:1 basis to control for baseline confounders. In-hospital mortality was compared between the two groups, and logistic regression analysis was performed to assess the association between B2As and in-hospital mortality.The initial search retrieved 2345 eligible patients with HF from the database. After propensity score matching, 705 pairs of patients were included in the final analysis. Patients using B2As had markedly higher in-hospital mortality than those not using B2As (4.68% versus 2.27%; P = 0.013). In the multivariate logistic regression analysis, B2A use (odd ratios (OR), 2.471; 95% confidence interval (CI), 1.289-4.734; P = 0.006), stroke (OR, 4.581; 95% CI, 1.621-12.948; P = 0.004), and simplified acute physiology score II (SAPS-II) scores (OR, 1.090; 95% CI, 1.064-1.116; P < 0.001) were significantly associated with increased risk of in-hospital mortality, whereas renin angiotensin system inhibitor use (OR, 0.396; 95% CI, 0.202-0.778; P = 0.007) was significantly associated with decreased risk of in-hospital mortality. Subgroup analysis further indicated that the association between B2A use and mortality was significant only in patients with HF without chronic pulmonary disease (OR, 2.427; 95% CI, 1.351-4.362; P = 0.003), but not in those with chronic pulmonary disease (OR, 2.094; 95% CI, 0.582-7.537; P = 0.258).In ICU patients with HF but without chronic pulmonary disease, the use of inhaled B2As is associated with increased in-hospital mortality.

Investigation of the Sympathetic Regulation in Delayed Onset Muscle Soreness: Results of an RCT

Sports-related pain and injury is directly linked to tissue inflammation, thus involving the autonomic nervous system (ANS). In the present experimental study, we disable the sympathetic part of the ANS by applying a stellate ganglion block (SGB) in an experimental model of delayed onset muscle soreness (DOMS) of the biceps muscle. We included 45 healthy participants (female 11, male 34, age 24.16 ± 6.67 years [range 18-53], BMI 23.22 ± 2.09 kg/m2) who were equally randomized to receive either (i) an SGB prior to exercise-induced DOMS (preventive), (ii) sham intervention in addition to DOMS (control/sham), or (iii) SGB after the induction of DOMS (rehabilitative). The aim of the study was to determine whether and to what extent sympathetically maintained pain (SMP) is involved in DOMS processing. Focusing on the muscular area with the greatest eccentric load (biceps distal fifth), a significant time × group interaction on the pressure pain threshold was observed between preventive SGB and sham (p = 0.034). There was a significant effect on pain at motion (p = 0.048), with post hoc statistical difference at 48 h (preventive SGB Δ1.09 ± 0.82 cm VAS vs. sham Δ2.05 ± 1.51 cm VAS; p = 0.04). DOMS mediated an increase in venous cfDNA -as a potential molecular/inflammatory marker of DOMS- within the first 24 h after eccentric exercise (time effect p = 0.018), with a peak at 20 and 60 min. After 60 min, cfDNA levels were significantly decreased comparing preventive SGB to sham (unpaired t-test p = 0.008). At both times, 20 and 60 min, cfDNA significantly correlated with observed changes in PPT. The 20-min increase was more sensitive, as it tended toward significance at 48 h (r = 0.44; p = 0.1) and predicted the early decrease of PPT following preventive stellate blocks at 24 h (r = 0.53; p = 0.04). Our study reveals the broad impact of the ANS on DOMS and exercise-induced pain. For the first time, we have obtained insights into the sympathetic regulation of pain and inflammation following exercise overload. As this study is of a translational pilot character, further research is encouraged to confirm and specify our observations.

Glucocorticoid resistance and β2-adrenergic receptor signaling pathways promote peripheral pro-inflammatory conditions associated with chronic psychological stress: A systematic review across species

Activation of the HPA-axis and SNS are widely accepted to link chronic stress with elevated levels of peripheral pro-inflammatory markers in blood. Yet, empirical evidence showing that peripheral levels of glucocorticoids and/or catecholamines mediate this effect is equivocal. Recent attention has turned to the possibility that cellular sensitivity to these ligands may contribute to inflammatory mediators that accompany chronic stress. We review current evidence for the association of chronic stress with glucocorticoid receptor (GR) and β-adrenergic receptor (β-AR) signaling sensitivity. Across 15 mouse, 7 primate, and 19 human studies, we found that chronic stress reliably associates with downregulation in cellular GR sensitivity, alterations in intracellular β-AR signaling, and upregulation in pro-inflammatory biomarkers in peripheral blood. We also present evidence that alterations in GR and β-AR signaling may be specific to myeloid progenitor cells such that stress-related signaling promotes release of cells that are inherently less sensitive to glucocorticoids and differentially sensitive to catecholamines. Our findings have broad implications for understanding mechanisms by which chronic stress may contribute to pro-inflammatory phenotypes.

Centrally Projecting Edinger-Westphal Nucleus in the Control of Sympathetic Outflow and Energy Homeostasis

The centrally projecting Edinger-Westphal nucleus (EWcp) is a midbrain neuronal group, adjacent but segregated from the preganglionic Edinger-Westphal nucleus that projects to the ciliary ganglion. The EWcp plays a crucial role in stress responses and in maintaining energy homeostasis under conditions that require an adjustment of energy expenditure, by virtue of modulating heart rate and blood pressure, thermogenesis, food intake, and fat and glucose metabolism. This modulation is ultimately mediated by changes in the sympathetic outflow to several effector organs, including the adrenal gland, heart, kidneys, brown and white adipose tissues and pancreas, in response to environmental conditions and the animal's energy state, providing for appropriate energy utilization. Classic neuroanatomical studies have shown that the EWcp receives inputs from forebrain regions involved in these functions and projects to presympathetic neuronal populations in the brainstem. Transneuronal tracing with pseudorabies virus has demonstrated that the EWcp is connected polysynaptically with central circuits that provide sympathetic innervation to all these effector organs that are critical for stress responses and energy homeostasis. We propose that EWcp integrates multimodal signals (stress, thermal, metabolic, endocrine, etc.) and modulates the sympathetic output simultaneously to multiple effector organs to maintain energy homeostasis under different conditions that require adjustments of energy demands.

GFAP and desmin expression in lymphatic tissues leads to difficulties in distinguishing between glial and stromal cells

Recently, we found many immune cells including antigen presenting cells neurally hard wired in the T-cell zone of most lymphoid organs like amongst others, lymph nodes in rats, mice and humans. Single immune cells were reached by single neurites and enclosed with a dense neural meshwork. As it is well known that axons are always accompanied by glial cells, we were able to identify Schwann cells in the hilum, medullary and capsule region, like expected. Unexpected was the result, that we found oligodendrocyte-like cells in these regions, myelinating more than one axon. Likewise important was the finding, that one of the standard glial markers used, a polyclonal GFAP antibody equally bound to desmin and therefore marked nearly all stromal cells in cortical, paracortical and medullary cord regions. More detailed analysis showed that these results also appeared in many other non-lymphoid organs. Therefore, polyclonal GFAP antibodies are only conditionally usable for immunohistochemical analysis in peripheral tissues outside the central nervous system. It remains to be elucidated, if the binding of the GFAP antibody to desmin has its reason in a special desmin variant that can give stromal cells glial character.

Non-invasive transcutaneous vagal nerve stimulation improves myocardial performance in doxorubicin-induced cardiotoxicity

AIMS

The clinical use of antitumor agent doxorubicin (DOX) is hampered by its dose-dependent cardiotoxicity. Development of highly efficient and safe adjuvant intervention for preventing DOX-induced adverse cardiac events is urgently needed. We aimed to investigate whether transcutaneous vagal nerve stimulation (tVNS) plays a cardio-protective role in DOX-induced cardiotoxicity.

METHODS AND RESULTS

Healthy male adult Sprague Dawley rats were used in the experiment and were randomly divided into four groups including control, DOX, tVNS and DOX+tVNS groups. A cumulative dose of 15 mg/kg DOX was intraperitoneally injected into rats to generate cardiotoxicity. Non-invasive tVNS was conducted for 6 weeks (30 min/day). After six-week intervention, the indices from the echocardiography revealed that tVNS significantly improved left ventricular function compared to the DOX group. The increased malondialdehyde (MDA) and Interleukin-1β (IL-1β), and decreased superoxide dismutase (SOD) were observed in the DOX group, while tVNS significantly prevented these changes. From cardiac histopathological analysis, the DOX+tVNS group showed a mild myocardial damage, and decreases in cardiac fibrosis and myocardial apoptosis compared to the DOX group. Heart rate variability (HRV) analysis showed that tVNS significantly inhibited DOX-induced sympathetic hyperactivity compared to the DOX group. Additionally, the results of RNA-sequencing analysis showed that there were 245 differentially expressed genes in the DOX group compared to the control group, among which 39 genes were downregulated by tVNS and most of these genes were involved in immune system. Moreover, tVNS significantly downregulated the relative mRNA expressions of chemokine-related genes and macrophages recruitment compared to the DOX group.

CONCLUSION

These results suggest that tVNS prevented DOX-induced cardiotoxicity by rebalancing autonomic tone, ameliorating cardiac dysfunction and remodeling. Notably, crosstalk between autonomic neuromodulation and innate immune cells macrophages mediated by chemokines might be involved in the underlying mechanisms.

A TRANSLATIONAL PERSPECTIVE

Non-invasive tVNS has been identified an effective neuromodulation strategy exerting beneficial effects on rebalancing autonomic tone and cardiac pathological conditions. The present study provided direct evidence for a beneficial role of tVNS in preventing DOX-induced autonomic dysfunction and cardiotoxicity in vivo. Additionally, recent studies revealed the importance of sympathetic nerve fibers involving in tumorigenesis and the benefits of higher vagal tone for tumor prognosis either in animal or human trials. Together, tVNS may not only become a novel, nonpharmacological adjuvant therapy for preventing doxorubicin-induced cardiotoxicity, but also may be beneficial for prognosis of cancer patients during chemotherapy. In our future study, we would investigate the effect of tVNS on both combined chemotherapy-induced cardiotoxicity and the antitumor efficacy of DOX in tumor models.

The two-faced effects of nerves and neuropeptides in corneal diseases

Corneal nerves are instrumental to maintain cornea integrity through regulation of key physiological functions such as tear secretion, blink reflex, and neuropeptide turnover. Corneal nerve injury/stimulation can follow many insults including mechanical/chemical trauma, infections and surgeries. Nerve disruption initiates a process named neurogenic inflammation which leads to edema, pain, and recruitment and activation of leukocytes. Interestingly, leukocyte influx in the cornea can further damage nerves by releasing inflammatory mediators-including neuropeptides. The clinical outcome of neuroinflammation can be beneficial or detrimental to corneal integrity. On one side, it ensures prompt wound healing and prevents infections. On the other, prolonged and/or deranged neuroinflammation can permanently disrupt corneal integrity and impair vision. The cornea is an ideal site to study peripheral neuroinflammation and neurogenic inflammation since it receives the highest density of sensory nerves of the entire body. We will review the corneal nerve anatomy and neurochemistry, discuss the beneficial and detrimental effects of neurogenic inflammation in corneal wound healing, inflammatory processes, and pain. We will also examine the emerging remote impact of corneal nerve disruption on the trigeminal ganglion and the brain, highlighting the key role of neuropeptide Substance P. Finally, we will discuss the clinical relevance of such neuroinflammatory network in the context of severe and highly prevalent ocular diseases, including potential treatments.

Neuroimmune interactions in peripheral tissues

Neuroimmune interactions have been revealed to be at the centre stage of tissue defence, organ homeostasis, and organismal physiology. Neuronal and immune cell subsets have been shown to colocalize in discrete tissue environments, forming neuroimmune cell units that constitute the basis for bidirectional interactions. These multitissue units drive coordinated neuroimmune responses to local and systemic signals, which represents an important challenge to our current views of mucosal physiology and immune regulation. In this review, we focus on the impact of reciprocal neuroimmune interactions, focusing on the anatomy of neuronal innervation and on the neuronal regulation of immune cells in peripheral tissues. Finally, we shed light on recent studies that explore how neuroimmune interactions maximise sensing and integration of environmental aggressions, modulating immune function in health and disease.

Heart Rate Variability and Circulating Inflammatory Markers in Midlife

Theoretical perspectives and empirical evidence suggest that the parasympathetic nervous system engages in active monitoring and moderating of inflammatory processes. A clearer understanding of the bidirectional communication between the parasympathetic nervous system and the immune system could lead to novel clinical interventions for inflammatory illnesses. The current study used a large (N ​= ​836) nationally representative sample of adults in the United States to investigate the associations between resting parasympathetic modulation of the heart, indexed through both high frequency heart rate variability (HF-HRV) and low frequency heart rate variability (LF-HRV), and six circulating markers of inflammation. Statistical analyses revealed robust inverse associations of HF-HRV with interleukin-6 (IL6), C-reactive protein (CRP), and fibrinogen, with or without covariate adjustment. Similar inverse associations were observed between LF-HRV and IL6 and CRP. No significant associations were observed between HRV and either inflammatory adhesion molecules (E-selectin, intracellular adhesion molecule-1) or soluble IL6 receptor. Results are consistent with the cholinergic anti-inflammatory pathway and suggest that parasympathetic modulation of inflammation through the vagus nerve may act on specific inflammatory molecules more than others.