Sympathetic Nerve Hyperactivity in the Spleen: Causal for Nonpathogenic-Driven Chronic Immune-Mediated Inflammatory Diseases (IMIDs)?

Inflammatory bowel disease and rheumatoid arthritis share a common genetic structure

Background

The comorbidity rate of inflammatory bowel disease (IBD) and rheumatoid arthritis (RA) is high; nevertheless, the reasons behind this high rate remain unclear. Their similar genetic makeup probably contributes to this comorbidity.

Methods

Based on data obtained from the genome-wide association study of IBD and RA, we first assessed an overall genetic association by performing the linkage disequilibrium score regression (LDSC) analysis. Further, a local correlation analysis was performed by estimating the heritability in summary statistics. Next, the causality between the two diseases was analyzed by two-sample Mendelian randomization (MR). A genetic overlap was analyzed by the conditional/conjoint false discovery rate (cond/conjFDR) method.LDSC with specific expression of gene analysis was performed to identify related tissues between the two diseases. Finally, GWAS multi-trait analysis (MTAG) was also carried out.

Results

IBD and RA are correlated at the genomic level, both overall and locally. The MR results suggested that IBD induced RA. We identified 20 shared loci between IBD and RA on the basis of a conjFDR of <0.01. Additionally, we identified two tissues, namely spleen and small intestine terminal ileum, which were commonly associated with both IBD and RA.

Conclusion

Herein, we proved the presence of a polygenic overlap between the genetic makeup of IBD and RA and provided new insights into the genetic architecture and mechanisms underlying the high comorbidity between these two diseases.

Autonomic nervous system imbalance during aging contributes to impair endogenous anti-inflammaging strategies

Inflammaging refers to the age-related low grade, sterile, chronic, systemic, and long-lasting subclinical, proinflammatory status, currently recognized as the main risk factor for development and progression of the most common age-related diseases (ARDs). Extensive investigations were focused on a plethora of proinflammatory stimuli that can fuel inflammaging, underestimating and partly neglecting important endogenous anti-inflammaging mechanisms that could play a crucial role in such age-related proinflammatory state. Studies on autonomic nervous system (ANS) functions during aging highlighted an imbalance toward an overactive sympathetic nervous system (SNS) tone, promoting proinflammatory conditions, and a diminished parasympathetic nervous system (PNS) activity, playing anti-inflammatory effects mediated by the so called cholinergic anti-inflammatory pathway (CAP). At the molecular level, CAP is characterized by signals communicated via the vagus nerve (with the possible involvement of the splenic nerves) through acetylcholine release to downregulate the inflammatory actions of macrophages, key players of inflammaging. Notably, decreased vagal function and increased burden of activated/senescent macrophages (macrophaging) probably precede the development of several age-related risk factors and diseases, while increased vagal function and reduced macrophaging could be associated with relevant reduction of risk profiles. Hypothalamic-pituitary-adrenal axis (HPA axis) is another pathway related to ANS promoting some anti-inflammatory response mainly through increased cortisol levels. In this perspective review, we highlighted that CAP and HPA, representing broadly "anti-inflammaging" mechanisms, have a reduced efficacy and lose effectiveness in aged people, a phenomenon that could contribute to fuel inflammaging. In this framework, strategies aimed to re-balance PNS/SNS activities could be explored to modulate systemic inflammaging especially at an early subclinical stage, thus increasing the chances to reach the extreme limit of human lifespan in healthy status.

Central stress pathways in the development of cardiovascular disease

PURPOSE

Mental stress is of essential consideration when assessing cardiovascular pathophysiology in all patient populations. Substantial evidence indicates associations among stress, cardiovascular disease and aberrant brain-body communication. However, our understanding of the flow of stress information in humans, is limited, despite the crucial insights this area may offer into future therapeutic targets for clinical intervention.

METHODS

Key terms including mental stress, cardiovascular disease and central control, were searched in PubMed, ScienceDirect and Scopus databases. Articles indicative of heart rate and blood pressure regulation, or central control of cardiovascular disease through direct neural innervation of the cardiac, splanchnic and vascular regions were included. Focus on human neuroimaging research and the flow of stress information is described, before brain-body connectivity, via pre-motor brainstem intermediates is discussed. Lastly, we review current understandings of pathophysiological stress and cardiovascular disease aetiology.

RESULTS

Structural and functional changes to corticolimbic circuitry encode stress information, integrated by the hypothalamus and amygdala. Pre-autonomic brain-body relays to brainstem and spinal cord nuclei establish dysautonomia and lead to alterations in baroreflex functioning, firing of the sympathetic fibres, cellular reuptake of norepinephrine and withdrawal of the parasympathetic reflex. The combined result is profoundly adrenergic and increases the likelihood of cardiac myopathy, arrhythmogenesis, coronary ischaemia, hypertension and the overall risk of future sudden stress-induced heart failure.

CONCLUSIONS

There is undeniable support that mental stress contributes to the development of cardiovascular disease. The emerging accumulation of large-scale multimodal neuroimaging data analytics to assess this relationship promises exciting novel therapeutic targets for future cardiovascular disease detection and prevention.

Locus coeruleus tyrosine hydroxylase positive neurons mediated the peripheral and central therapeutic effects of transcutaneous auricular vagus nerve stimulation (taVNS) in MRL/lpr mice

OBJECTIVE

This study aims to investigate the effects of transcutaneous auricular vagus nerve stimulation (taVNS) on the development of systemic lupus erythematosus (SLE) in MRL/lpr mice.

METHODS

MRL/lpr mice were treated with taVNS for ten weeks. Locus coeruleus (LC) tyrosine hydroxylase positive (TH+) neurons were selectively lesioned by stereotactic injection of 6-hydroxydopamine (6-OHDA) or selectively activated by chemogenetic methods. Sympathetic denervation was conducted by intraperitoneal injection of 6-OHDA.

RESULTS

TaVNS activated the TH + neurons in LC. TaVNS produced central therapeutic effects by reducing the number of hippocampal microglia, and increasing the number of surviving LC TH+ neurons in MRL/lpr mice. TaVNS also retarded the development of lymphadenectasis and splenomegaly, decreased the proportion of double-negative T (DNT) cells, and alleviated nephritis in MRL/lpr mice. The lesion of LC TH+ neurons eliminated both these central and peripheral therapeutic effects of taVNS, while chemogenetic activation of LC TH+ neurons mimicked most central and peripheral protective effects of taVNS in MRL/lpr mice. Furthermore, taVNS regulated the autonomic nervous system in MRL/lpr mice.

CONCLUSION

This study provides direct evidence that taVNS can retard the development of peripheral and central symptoms of SLE, which is mediated by the LC TH+ neurons.

The mechanisms underlying alcohol-induced decreased splenic size: A network meta-analysis study

BACKGROUND

Organ weight change is widely accepted as a measure of toxicologic pathology. We and other groups have shown that excessive alcohol exposure leads to decreased spleen weight in rodents. This study explores the mechanisms underlying alcohol-induced splenic injury through a network meta-analysis.

METHODS

QIAGEN Ingenuity Pathway Analysis (IPA) and Mammalian Phenotype (MP) Ontology were used to identify alcohol-related molecules associated with the small spleen phenotype. Search Tool for the Retrieval of Interacting Genes/Proteins (STRING) and IPA bioinformatics tools were then used to analyze the biologic processes and enriched signaling pathways engaging these molecules. In addition, the "downstream effects analysis" algorithm was used to quantify alcohol's effects.

RESULTS

IPA identified 623 molecules affected by alcohol and a Venn diagram revealed that 26 of these molecules overlapped with those associated with the MP Ontology of small spleen. The 26 molecules are TGFB1, CASP8, MTOR, ESR1, CXCR4, CAMK4, NFKBIA, DRD2, BCL2, FAS, PEBP1, TRAF2, ATM, IGHM, EDNRB, MDM2, GLRA1, PRF1, TLR7, IFNG, ALOX5, FOXO1, IL15, APOE, IKBKG, and RORA. Some of the 26 molecules were also associated with the MP Ontology of abnormal white pulp and red pulp morphology of the spleen, abnormal splenic cell ratio, decreased splenocyte number, abnormal spleen physiology, increased splenocyte apoptosis, and reduced splenocyte proliferation. STRING and IPA "Core Analysis" showed that these molecules were mainly involved in pathways related to cell apoptosis, proliferation, migration, and immune responses. IPA's "Molecular Activity Predictor" tool showed that concurrent effects of activation and inhibition of these molecules led to decreased spleen size by modulating apoptosis, proliferation, and migration of splenocytes.

CONCLUSIONS

Our network meta-analysis revealed that excessive alcohol exposure can damage the spleen through a variety of molecular mechanisms, thereby affecting immune function and human health. We found that alcohol-mediated splenic atrophy is largely mediated by increased apoptosis signaling, migration of cells, and inhibition of splenocyte proliferation.

CP-25 inhibits the hyperactivation of rheumatic synoviocytes by suppressing the switch in Gαs-Gαi coupling to the β2-adrenergic receptor

In essence, the β2 adrenergic receptor (β2AR) plays an antiproliferative role by increasing the intracellular cyclic 3',5'-adenosine monophosphate (cAMP) concentration through Gαs coupling, but interestingly, β2AR antagonists are able to effectively inhibit fibroblast-like synoviocytes (FLSs) proliferation, thus ameliorating experimental RA, indicating that the β2AR signalling pathway is impaired in RA FLSs via unknown mechanisms. The local epinephrine (Epi) level was found to be much higher in inflammatory joints than in normal joints, and high-level stimulation with Epi or isoproterenol (ISO) directly promoted FLSs proliferation and migration due to impaired β2AR signalling and cAMP production. By applying inhibitor of receptor internalization, and small interfering RNA (siRNA) of Gαs and Gαi, and by using fluorescence resonance energy transfer and coimmunoprecipitation assays, a switch in Gαs-Gαi coupling to β2AR was observed in inflammatory FLSs as well as in FLSs with chronic ISO stimulation. This Gαi coupling was then revealed to be initiated by G protein coupled receptor kinase 2 (GRK2) but not β-arrestin2 or protein kinase A-mediated phosphorylation of β2AR. Inhibiting the activity of GRK2 with the novel GRK2 inhibitor paeoniflorin-6'-O-benzene sulfonate (CP-25), a derivative of paeoniflorin, or the accepted GRK2 inhibitor paroxetine effectively reversed the switch in Gαs-Gαi coupling to β2AR during inflammation and restored the intracellular cAMP level in ISO-stimulated FLSs. As expected, CP-25 significantly inhibited the hyperplasia of FLSs in a collagen-induced arthritis (CIA) model (CIA FLSs) and normal FLSs stimulated with ISO and finally ameliorated CIA in rats. Together, our findings revealed the pathological changes in β2AR signalling in CIA FLSs, determined the underlying mechanisms and identified the pharmacological target of the GRK2 inhibitor CP-25 in treating CIA. Video Abstract.

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

BACKGROUND

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

OBJECTIVE

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

METHODS

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

RESULTS

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

CONCLUSIONS

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

TRIAL REGISTRATION

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

INTERNATIONAL REGISTERED REPORT IDENTIFIER (IRRID)

DERR1-10.2196/48387.

Sympathetic Nerves Coordinate Corneal Epithelial Wound Healing by Controlling the Mobilization of Ly6Chi Monocytes From the Spleen to the Injured Cornea

Purpose

This study aims to investigate the potential involvement of spleen-derived monocytes in the repair process following corneal epithelial abrasion.

Methods

A corneal epithelial abrasion model was established in male C57BL/6J mice, and the dynamic changes of monocyte subpopulations in the injured cornea were analyzed using flow cytometry. The effects of Ly6Chi monocyte depletion and local adoptive transfer of purified Ly6Chi monocytes on wound closure and neutrophil recruitment to the injured cornea were observed. The effect of sympathetic nerves on the recruitment of spleen-derived Ly6Chi monocytes to the injured cornea was also investigated using multiple methods. The emigration of fluorescence-labeled monocytes to the injured cornea was validated through intravital microscopy. Finally, differential genes between different groups were identified through high-throughput RNA sequencing and analyzed for functional enrichment, followed by verification by quantitative PCR.

Results

Ly6Chi monocytes were present in large numbers in the injured cornea prior to neutrophil recruitment. Predepletion of Ly6Chi monocytes significantly inhibited neutrophil recruitment to the injured cornea. Furthermore, surgical removal of the spleen significantly reduced the number of Ly6Chi monocytes in the injured cornea. Further observations revealed that sympathetic blockade significantly reduced the number of Ly6Chi monocytes recruited to the injured cornea. In contrast, administration of the β2-adrenergic receptor agonist significantly increased the number of Ly6Chi monocytes recruited to the injured cornea in animals treated with sympathectomy and catecholamine synthesis inhibition.

Conclusions

Our results suggest that spleen-derived Ly6Chi monocytes, under the control of the sympathetic nervous system, play a critical role in the inflammatory response following corneal injury.

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.

The widespread myofascial pain of fibromyalgia is sympathetically maintained and immune mediated

The recent demonstration of antibody-induced passive transfer of pain hypersensitivity from fibromyalgia (FM) subjects to mice brings renewed focus to the role of the immune system in generating FM pain. However, this data must be interpreted in the context of known myofascial pathology in FM, which includes impaired muscle relaxation and elevated intramuscular pressure. In addition, FM fascial biopsies demonstrate elevated inflammatory and oxidative stress markers and increased endomysial collagen deposition. This article proposes a unifying hypothesis for FM pain generation that connects known muscle and fascia abnormalities with the newly discovered role of antibodies. FM is characterized by persistent sympathetic nervous system hyperactivity which results in both pathologic muscle tension and an impaired tissue healing response. Although autoantibodies play a key role in normal tissue healing, sympathetic nervous system hyperactivity impairs the resolution of inflammation, and promotes autoimmunity and excessive autoantibody production. These autoantibodies can then bind with myofascial-derived antigen to create immune complexes, which are known to trigger neuronal hyperexcitability in the dorsal root ganglion. These hyperexcited sensory neurons activate the surrounding satellite glial cells and spinal microglia leading to pain hypersensitivity and central sensitization. Although immune system modulation may become an important treatment tool in FM, direct manual treatments that lessen myofascial inflammation and tension must not be neglected. Myofascial release therapy significantly reduces FM pain, with residual benefits even after the conclusion of treatment. Self-myofascial release techniques and gentle stretching programs also ease fibromyalgia pain, as do trigger point injections and dry-needling.

β2-adrenergic receptor agonist corrects immune thrombocytopenia by reestablishing the homeostasis of T cell differentiation

BACKGROUND

The sympathetic nerve is known to regulate immune responses in autoimmunity. Aberrant T cell immunity plays a vital role in immune thrombocytopenia (ITP) pathogenesis. The spleen is the primary site of platelet destruction. However, little is known whether and how splenic sympathetic innervation and neuroimmune modulation contribute to ITP pathogenesis.

OBJECTIVES

To determine the sympathetic distribution in the spleen of ITP mice and the association between splenic sympathetic nerves and T cell immunity in ITP development, and to evaluate the treatment potential of β2-adrenergic receptor (β2-AR) in ITP.

METHODS

Chemical sympathectomy was performed in an ITP mouse model with 6-hydroxydopamine and treated with β2-AR agonists to evaluate the effects of sympathetic denervation and activation.

RESULTS

Decreased sympathetic innervation in the spleen of ITP mice was observed. Significantly increased percentages of Th1 and Tc1 cells and reduced percentages of regulatory T cells (Tregs) were also observed in ITP mice with chemical sympathectomy (ITP-syx mice) relative to mice without sympathectomy (controls). Expression of genes associated with Th1, including IFN-γ and IRF8, was significantly upregulated, whereas genes associated with Tregs, including Foxp3 and CTLA4, were significantly downregulated in ITP-syx mice compared with controls. Furthermore, β2-AR restored the percentage of Tregs and increased platelet counts at days 7 and 14 in ITP mice.

CONCLUSION

Our findings indicate that decreased sympathetic distribution contributes to ITP pathogenesis by disturbing the homeostasis of T cells and that β2-AR agonists have potential as a novel treatment for ITP.

Chronic psychological stress aggravates psoriasis-like skin inflammation via overactivation of β2-adrenoceptor and nuclear factor kappa B pathways

The relationship between psoriasis severity and psychological stress has been described in several studies. However, the mechanism by which chronic stress exacerbates psoriasis is not completely understood. This study aimed at investigating whether chronic psychological stress can aggravate psoriasis-like skin inflammation. Mice were subjected to a restraint stress model and topically treated with imiquimod (IMQ). Differentiated human keratinocytes were treated with high epinephrine levels and IMQ in vitro. Stress aggravated macroscopic features and the increase in epidermal thickness induced by IMQ in mouse skin. The increase in NF-κB and IL-17A expression induced by IMQ was potentiated by chronic stress in mouse skin. The skin of stressed mice treated with IMQ showed higher levels of β2-adrenergic receptors (β2-AR). In human keratinocytes, high epinephrine levels exacerbated the increase in the levels of β2-AR and IL-17A induced by IMQ. β-AR antagonist reversed the effects of chronic stress in IMQ-induced inflammation both in vivo and in vitro. In conclusion, stress-stimulated overactivation of the β2-AR and NF-κB pathways potentiates a Th1/Th17 profile leading to an exacerbation of psoriasis.

ProBDNF and its receptors in immune-mediated inflammatory diseases: novel insights into the regulation of metabolism and mitochondria

Immune-mediated inflammatory diseases (IMIDs) consist of a common and clinically diverse group of diseases. Despite remarkable progress in the past two decades, no remission is observed in a large number of patients, and no effective treatments have been developed to prevent organ and tissue damage. Brain-derived neurotrophic factor precursor (proBDNF) and receptors, such as p75 neurotrophin receptor (p75^NTR) and sortilin, have been proposed to mediate intracellular metabolism and mitochondrial function to regulate the progression of several IMIDs. Here, the regulatory role of proBDNF and its receptors in seven typical IMIDs, including multiple sclerosis, rheumatoid arthritis, systemic lupus erythematosus, allergic asthma, type I diabetes, vasculitis, and inflammatory bowel diseases, was investigated.

Role of neurotransmitters in immune-mediated inflammatory disorders: a crosstalk between the nervous and immune systems

Immune-mediated inflammatory diseases (IMIDs) are a group of common heterogeneous disorders, characterized by an alteration of cellular homeostasis. Primarily, it has been shown that the release and diffusion of neurotransmitters from nervous tissue could result in signaling through lymphocyte cell-surface receptors and the modulation of immune function. This finding led to the idea that the neurotransmitters could serve as immunomodulators. It is now manifested that neurotransmitters can also be released from leukocytes and act as autocrine or paracrine modulators. Increasing data indicate that there is a crosstalk between inflammation and alterations in neurotransmission. The primary goal of this review is to demonstrate how these two pathways may converge at the level of the neuron and glia to involve in IMID. We review the role of neurotransmitters in IMID. The different effects that these compounds exert on a variety of immune cells are also reviewed. Current and future developments in understanding the cross-talk between the immune and nervous systems will undoubtedly identify new ways for treating immune-mediated diseases utilizing agonists or antagonists of neurotransmitter receptors.

Heart rate variability and fatigue in MS: two parallel pathways representing disseminated inflammatory processes?

BACKGROUND

Fatigue is a disabling symptom of multiple sclerosis. Its biological causes are still poorly understood. Several years ago, we proposed that fatigue might be the subjective representation of inflammatory processes. An important step for a straight-forward evaluation of our model would be to show that the level of fatigue is associated with vagal activation. The heart rate is under partial control of the vagus nerve. Using power spectrum analysis allows to separate, at least partly, sympathetic and parasympathetic impact on heart rate variability.

METHODS

This narrative review summarizes the evidence for heart rate variability changes in MS patients, their relationship with fatigue and disease course. To do this, we conducted a literature search, including 45 articles relevant to the topic treated in this review.

RESULTS

We illustrate that (1) inflammation leads to a change in cardiac behavior during acute and chronic phases, both in animals and in humans; (2) MS patients show changes of heart rate variability (HRV) that resemble those during acute and chronic inflammation due to multiple causes; (3) existing evidence favors a set of specific predictions about fatigue and parallel HRV changes; and (4) that MS-related brainstem lesions or neurological impairments do not completely explain HRV changes, leaving enough place for an explanatory relation between HRV and fatigue.

DISCUSSION

We discuss the results of this review in relation to our model of fatigue and propose several observational and experimental studies that could be conducted to gain a better insight into whether fatigue and HRV can be interpreted as a common pathway, both reflecting activated autoimmune processes in MS patients.

Sympatho-Vagal Dysfunction in Systemic Sclerosis: A Follow-Up Study

Systemic sclerosis (SSc) patients often present cardiovascular autonomic dysfunction, which is associated with the risk of arrhythmic complications and mortality. However, little is known regarding the progression of cardiac autonomic impairment over time. We aimed to evaluate the cardiac autonomic modulation among SSc with limited cutaneous (lcSSc), diffuse cutaneous (dcSSc) subset, and age-matched healthy control (HC) at baseline (t0) and five-year follow-up (t1). In this follow-up study, ECG was recorded at t0 and t1 in twenty-four SSc patients (dcSSc; n = 11 and lcSSc; n = 13) and 11 HC. The heart rate variability (HRV) analysis was conducted. The spectral analysis identified two oscillatory components, low frequency (LF) and high frequency (HF), and the sympatho-vagal balance was assessed by the LF/HF ratio. The LF/HF increased (p = 0.03), and HF reduced at t1 compared to t0 in dcSSc (p = 0.03), which did not occur in the lcSSc and HC groups. Otherwise, both lcSSc and dcSSc groups presented augmented LF/HF at t0 and t1 compared to HC (p < 0.01). In conclusion, a worsening of cardiac autonomic dysfunction is related to the dcSSc subset, in which a more extent of skin fibrosis and internal organs fibrosis is present.

The Relationship between Stress, Inflammation, and Depression

A narrative review about the relationship between stress, inflammation, and depression is made as follows: Chronic stress leads to various stress-related diseases such as depression. Although most human diseases are related to stress exposure, the common pathways between stress and pathophysiological processes of different disorders are still debatable. Chronic inflammation is a crucial component of chronic diseases, including depression. Both experimental and clinical studies have demonstrated that an increase in the levels of pro-inflammatory cytokines and stress hormones, such as glucocorticoids, substantially contributes to the behavioral alterations associated with depression. Evidence suggests that inflammation plays a key role in the pathology of stress-related diseases; however, this link has not yet been completely explored. In this study, we aimed to determine the role of inflammation in stress-induced diseases and whether a common pathway for depression exists. Recent studies support pharmacological and non-pharmacological treatment approaches significantly associated with ameliorating depression-related inflammation. In addition, major depression can be associated with an activated immune system, whereas antidepressants can exert immunomodulatory effects. Moreover, non-pharmacological treatments for major depression (i.e., exercise) may be mediated by anti-inflammatory actions. This narrative review highlights the mechanisms underlying inflammation and provides new insights into the prevention and treatment of stress-related diseases, particularly depression.

Bromocriptine-QR Therapy Reduces Sympathetic Tone and Ameliorates a Pro-Oxidative/Pro-Inflammatory Phenotype in Peripheral Blood Mononuclear Cells and Plasma of Type 2 Diabetes Subjects

Bromocriptine-QR is a sympatholytic dopamine D2 agonist for the treatment of type 2 diabetes that has demonstrated rapid (within 1 year) substantial reductions in adverse cardiovascular events in this population by as yet incompletely delineated mechanisms. However, a chronic state of elevated sympathetic nervous system activity and central hypodopaminergic function has been demonstrated to potentiate an immune system pro-oxidative/pro-inflammatory condition and this immune phenotype is known to contribute significantly to the advancement of cardiovascular disease (CVD). Therefore, the possibility exists that bromocriptine-QR therapy may reduce adverse cardiovascular events in type 2 diabetes subjects via attenuation of this underlying chronic pro-oxidative/pro-inflammatory state. The present study was undertaken to assess the impact of bromocriptine-QR on a wide range of immune pro-oxidative/pro-inflammatory biochemical pathways and genes known to be operative in the genesis and progression of CVD. Inflammatory peripheral blood mononuclear cell biology is both a significant contributor to cardiovascular disease and also a marker of the body’s systemic pro-inflammatory status. Therefore, this study investigated the effects of 4-month circadian-timed (within 2 h of waking in the morning) bromocriptine-QR therapy (3.2 mg/day) in type 2 diabetes subjects whose glycemia was not optimally controlled on the glucagon-like peptide 1 receptor agonist on (i) gene expression status (via qPCR) of a wide array of mononuclear cell pro-oxidative/pro-inflammatory genes known to participate in the genesis and progression of CVD (OXR1, NRF2, NQO1, SOD1, SOD2, CAT, GSR, GPX1, GPX4, GCH1, HMOX1, BiP, EIF2α, ATF4, PERK, XBP1, ATF6, CHOP, GSK3β, NFkB, TXNIP, PIN1, BECN1, TLR2, TLR4, TLR10, MAPK8, NLRP3, CCR2, GCR, L-selectin, VCAM1, ICAM1) and (ii) humoral measures of sympathetic tone (norepinephrine and normetanephrine), whole-body oxidative stress (nitrotyrosine, TBARS), and pro-inflammatory factors (IL-1β, IL-6, IL-18, MCP-1, prolactin, C-reactive protein [CRP]). Relative to pre-treatment status, 4 months of bromocriptine-QR therapy resulted in significant reductions of mRNA levels in PBMC endoplasmic reticulum stress-unfolded protein response effectors [GRP78/BiP (34%), EIF2α (32%), ATF4 (29%), XBP1 (25%), PIN1 (14%), BECN1 (23%)], oxidative stress response proteins [OXR1 (31%), NRF2 (32%), NQO1 (39%), SOD1 (52%), CAT (26%), GPX1 (33%), GPX4 (31%), GCH1 (30%), HMOX1 (40%)], mRNA levels of TLR pro-inflammatory pathway proteins [TLR2 (46%), TLR4 (20%), GSK3β (19%), NFkB (33%), TXNIP (18%), NLRP3 (32%), CCR2 (24%), GCR (28%)], mRNA levels of pro-inflammatory cellular receptor proteins CCR2 and GCR by 24% and 28%, and adhesion molecule proteins L-selectin (35%) and VCAM1 (24%). Relative to baseline, bromocriptine-QR therapy also significantly reduced plasma levels of norepinephrine and normetanephrine by 33% and 22%, respectively, plasma pro-oxidative markers nitrotyrosine and TBARS by 13% and 10%, respectively, and pro-inflammatory factors IL-18, MCP1, IL-1β, prolactin, and CRP by 21%,13%, 12%, 42%, and 45%, respectively. These findings suggest a unique role for circadian-timed bromocriptine-QR sympatholytic dopamine agonist therapy in reducing systemic low-grade sterile inflammation to thereby reduce cardiovascular disease risk.

Is PTSD an Evolutionary Survival Adaptation Initiated by Unrestrained Cytokine Signaling and Maintained by Epigenetic Change?

INTRODUCTION

Treatment outcomes for PTSD with current psychological therapies are poor, with very few patients achieving sustained symptom remission. A number of authors have identified physiological and immune disturbances in Post Traumatic Stress Disorder (PTSD) patients, but there is no unifying hypothesis that explains the myriad features of the disorder.

MATERIALS AND METHODS

The medical literature was reviewed over a 6-year period primarily using the medical database PUBMED.

RESULTS

The literature contains numerous papers that have identified a range of physiological and immune dysfunction in association with PTSD. This paper proposes that unrestrained cytokine signaling induces epigenetic changes that promote an evolutionary survival adaptation, which maintains a defensive PTSD phenotype. The brain can associate immune signaling with past threat and initiate a defensive behavioral response. The sympathetic nervous system is pro-inflammatory, while the parasympathetic nervous system is anti-inflammatory. Prolonged cholinergic withdrawal will promote a chronic inflammatory state. The innate immune cytokine IL-1β has pleiotropic properties and can regulate autonomic, glucocorticoid, and glutamate receptor functions, sleep, memory, and epigenetic enzymes. Changes in epigenetic enzyme activity can potentially alter phenotype and induce an adaptation. Levels of IL-1β correlate with severity and duration of PTSD and PTSD can be prevented by bolus administration of hydrocortisone in acute sepsis, consistent with unrestrained inflammation being a risk factor for PTSD. The nervous and immune systems engage in crosstalk, governed by common receptors. The benefits of currently used psychiatric medication may arise from immune, as well as synaptic, modulation. The psychedelic drugs (3,4-Methylenedioxymethamphetamine (MDMA), psilocybin, and ketamine) have potent immunosuppressive and anti-inflammatory effects on the adaptive immune system, which may contribute to their reported benefit in PTSD. There may be distinct PTSD phenotypes induced by innate and adaptive cytokine signaling.

CONCLUSION

In order for an organism to survive, it must adapt to its environment. Cytokines signal danger to the brain and can induce epigenetic changes that result in a persistent defensive phenotype. PTSD may be the price individuals pay for the genomic flexibility that promotes adaptation and survival.

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.

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

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

Therapeutic effects of menstrual blood-derived endometrial stem cells on mouse models of streptozotocin-induced type 1 diabetes

BACKGROUND

Type 1 diabetes (T1D), a chronic metabolic and autoimmune disease, seriously endangers human health. In recent years, mesenchymal stem cell (MSC) transplantation has become an effective treatment for diabetes. Menstrual blood-derived endometrial stem cells (MenSC), a novel MSC type derived from the decidual endometrium during menstruation, are expected to become promising seeding cells for diabetes treatment because of their noninvasive collection procedure, high proliferation rate and high immunomodulation capacity.

AIM

To comprehensively compare the effects of MenSC and umbilical cord-derived MSC (UcMSC) transplantation on T1D treatment, to further explore the potential mechanism of MSC-based therapies in T1D, and to provide support for the clinical application of MSC in diabetes treatment.

METHODS

A conventional streptozotocin-induced T1D mouse model was established, and the effects of MenSC and UcMSC transplantation on their blood glucose and serum insulin levels were detected. The morphological and functional changes in the pancreas, liver, kidney, and spleen were analyzed by routine histological and immunohistochemical examinations. Changes in the serum cytokine levels in the model mice were assessed by protein arrays. The expression of target proteins related to pancreatic regeneration and apoptosis was examined by western blot.

RESULTS

MenSC and UcMSC transplantation significantly improved the blood glucose and serum insulin levels in T1D model mice. Immunofluorescence analysis revealed that the numbers of insulin⁺ and CD31⁺ cells in the pancreas were significantly increased in MSC-treated mice compared with control mice. Subsequent western blot analysis also showed that vascular endothelial growth factor (VEGF), Bcl2, Bcl-xL and Proliferating cell nuclear antigen in pancreatic tissue was significantly upregulated in MSC-treated mice compared with control mice. Additionally, protein arrays indicated that MenSC and UcMSC transplantation significantly downregulated the serum levels of interferon γ and tumor necrosis factor α and upregulated the serum levels of interleukin-6 and VEGF in the model mice. Additionally, histological and immunohistochemical analyses revealed that MSC transplantation systematically improved the morphologies and functions of the liver, kidney, and spleen in T1D model mice.

CONCLUSION

MenSC transplantation significantly improves the symptoms in T1D model mice and exerts protective effects on their main organs. Moreover, MSC-mediated angiogenesis, antiapoptotic effects and immunomodulation likely contribute to the above improvements. Thus, MenSC are expected to become promising seeding cells for clinical diabetes treatment due to their advantages mentioned above.

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.

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.

Otitis Media in Childhood and Disease in Adulthood: A 40-Year Follow-Up Study

OBJECTIVES

The pathogenesis of chronic suppurative otitis media (CSOM) includes complex interactions between microbial, immunologic, and genetic factors. To our knowledge, no study has focused on the association between childhood otitis media, immune regulation, inflammatory conditions, and chronic disease in adulthood. The present study aims to assess whether CSOM in childhood predicts immune-related inflammatory disorders or cardiovascular disease in adulthood. Another aim is to assess the association with oto-vestibular diseases in adulthood.

DESIGN

Population cohort study in Norway comprised 51,626 participants (mean age 52 years) who underwent a hearing investigation at 7 to 13 years of age where 189 were diagnosed with CSOM (otorhinolaryngologist diagnose) and 51,437 had normal hearing thresholds (controls). Data on adult disease were obtained from the Norwegian Patient Registry (ICD-10 codes from the specialist health services). We estimated associations with logistic regression analyses.

RESULTS

The associations between CSOM in childhood and disease in adulthood were as follows: chronic sinusitis (odds ratio 3.13, 95% confidence interval 1.15 to 8.52); cardiovascular disease (1.38, 1.01 to 1.88); hearing loss (5.58, 3.78 to 8.22); tinnitus (2.62, 1.07 to 6.41). The adult hearing loss among cases with childhood CSOM was most frequently registered as sensorineural. There was no statistically significant increased risk of later asthma (1.84 [0.98 to 3.48]), inflammatory bowel disease, inflammatory joint disease, systemic tissue disease, or vestibulopathy. The estimates were adjusted for age, sex, socio-economic status, and smoking.

CONCLUSION

Our large cohort study, which is the first to focus on the link between otitis media in childhood and immune-related inflammatory disorders later in life, does not confer a clear association. CSOM in childhood was strongly related to adult tinnitus and hearing loss, which was most frequently registered as sensorineural.

Driving β2- While Suppressing α-Adrenergic Receptor Activity Suppresses Joint Pathology in Inflammatory Arthritis

Objective

Hypersympathetic activity is prominent in rheumatoid arthritis, and major life stressors precede onset in ~80% of patients. These findings and others support a link between stress, the sympathetic nervous system and disease onset and progression. Here, we extend previous research by evaluating how selective peripherally acting α/β2-adrenergic drugs affect joint destruction in adjuvant-induced arthritis.

Methods

Complete Freund's adjuvant induced inflammatory arthritis in male Lewis rats. Controls received no treatment. Arthritic rats then received vehicle or twice-daily treatment with the α-adrenergic antagonist, phentolamine (0.5 mg/day) and the β2-adrenergic agonist, terbutaline (1200 µg/day, collectively named SH1293) from day (D) of disease onset (D12) through acute (D21) and severe disease (D28). Disease progression was assessed in the hind limbs using dorsoplantar widths, X-ray analysis, micro-computed tomography, and routine histology on D14, D21, and D28 post-immunization.

Results

On D21, SH1293 significantly attenuated arthritis in the hind limbs, based on reduced lymphocytic infiltration, preservation of cartilage, and bone volume. Pannus formation and sympathetic nerve loss were not affected by SH1293. Bone area and osteoclast number revealed high- and low-treatment-responding groups. In high-responding rats, treatment with SH1293 significantly preserved bone area and decreased osteoclast number, data that correlated with drug-mediated joint preservation. SH1293 suppressed abnormal bone formation based on reduced production of osteophytes. On D28, the arthritic sparing effects of SH1293 on lymphocytic infiltration, cartilage and bone sparing were maintained at the expense of bone marrow adipocity. However, sympathetic nerves were retracted from the talocrural joint.

Conclusion and Significance

Our findings support a significant delay in early arthritis progression by treatment with SH1293. Targeting sympathetic neurotransmission may provide a strategy to slow disease progression.

Peripheral Vascular Abnormalities in Anorexia Nervosa: A Psycho-Neuro-Immune-Metabolic Connection

Immune, neuroendocrine, and autonomic nervous system dysregulation in anorexia nervosa lead to cardiovascular complications that can potentially result in increased morbidity and mortality. It is suggested that a complex non-invasive assessment of cardiovascular autonomic regulation-cardiac vagal control, sympathetic vascular activity, and cardiovascular reflex control-could represent a promising tool for early diagnosis, personalized therapy, and monitoring of therapeutic interventions in anorexia nervosa particularly at a vulnerable adolescent age. In this view, we recommend to consider in the diagnostic route, at least in the subset of patients with peripheral microvascular symptoms, a nailfold video-capillaroscopy as an easy not invasive tool for the early assessing of possible cardiovascular involvement.

Bidirectional Brain-Systemic Interactions and Outcomes After TBI

Traumatic brain injury (TBI) is a debilitating disorder associated with chronic progressive neurodegeneration and long-term neurological decline. Importantly, there is now substantial and increasing evidence that TBI can negatively impact systemic organs, including the pulmonary, gastrointestinal (GI), cardiovascular, renal, and immune system. Less well appreciated, until recently, is that such functional changes can affect both the response to subsequent insults or diseases, as well as contribute to chronic neurodegenerative processes and long-term neurological outcomes. In this review, we summarize evidence showing bidirectional interactions between the brain and systemic organs following TBI and critically assess potential underlying mechanisms.

Early-life-trauma triggers interferon-β resistance and neurodegeneration in a multiple sclerosis model via downregulated β1-adrenergic signaling

Environmental triggers have important functions in multiple sclerosis (MS) susceptibility, phenotype, and trajectory. Exposure to early life trauma (ELT) has been associated with higher relapse rates in MS patients; however, the underlying mechanisms are not well-defined. Here we show ELT induces mechanistic and phenotypical alterations during experimental autoimmune encephalitis (EAE). ELT sustains downregulation of immune cell adrenergic receptors, which can be attributed to chronic norepinephrine circulation. ELT-subjected mice exhibit interferon-β resistance and neurodegeneration driven by lymphotoxin and CXCR2 involvement. These phenotypic changes are observed in control EAE mice treated with β1 adrenergic receptor antagonist. Conversely, β1 adrenergic receptor agonist treatment to ELT mice abrogates phenotype changes via restoration of immune cell β1 adrenergic receptor function. Our results indicate that ELT alters EAE phenotype via downregulation of β1 adrenergic signaling in immune cells. These results have implications for the effect of environmental factors in provoking disease heterogeneity and might enable prediction of long-term outcomes in MS.

Heart rate variability and inflammatory bowel disease in humans: A systematic review and meta-analysis

The autonomic nervous system (ANS) maintains homeostasis in the gastrointestinal tract, including immunity, inflammation and motility, through the brain-gut axis. To date, the associations between ANS function and inflammatory bowel disease (IBD) have been controversial and inconclusive in human studies. PubMed, Cochrane Library, and Embase were searched through February 2020 for articles reporting these association between heart rate variability (HRV), an indirect measure of ANS activity, and IBD. The standardized mean differences and 95% confidence intervals (CIs) were calculated. Ten eligible studies involving 273 ulcerative colitis patients, 167 Crohn's disease patients and 208 healthy controls were included. The values of the total power (SMD = -0.83, 95% CI = -1.44, -0.21), high frequency (SMD = -0.79, 95% CI = -1.20, -0.38), RR interval (SMD = -0.66, 95% CI = -1.04, -0.27), standard deviation of the RR intervals (SMD = -1.00, 95% CI = -1.73, -0.27), percentage of RR intervals with a greater than 50-millisecond variation (SMD = -0.82, 95% CI = -1.33, -0.30) and the square root of the mean squared differences in successive RR intervals (SMD = -0.71, 95% CI = -1.15, -0.26) of the IBD patients were lower than those of the healthy controls, and moderate to large effect sizes were observed in all HRV indices, except for low frequency (SMD = -0.41, 95% CI = 0.95, 0.13). IBD was strongly associated with an overall decrease in HRV, indicating substantially decreased ANS activity. Furthermore, the parasympathetic nerve displayed a stronger inverse association with ANS activity than the sympathetic nerve, indicating ANS dysfunction in patients with IBD.

Cardiac Autonomic Modulation Is Different in Terms of Clinical Variant of Multiple Sclerosis

This study evaluates whether the cardiac autonomic response to head-up tilt test (HUTT) differs between patients with relapsing-remitting multiple sclerosis (RRMS) and those with progressive MS (PMS) as compared to healthy controls (HC). Baroreflex sensitivity, cardiac parameters, heart rate (HRV) and blood pressure variability (BPV) were compared between 28 RRMS, 21PMS and 25 HC during HUTT. At rest, PMS patients had higher values of the sympathovagal ratio, a low-frequency band HRV (LFnu-RRI) and lower values of parasympathetic parameters (HFnu-RRI, HF-RRI) compared to RRMS and HC. Resting values of cardiac parameters were significantly lower in RRMS compared to PMS patients. No intergroup differences were observed for post-tilt cardiac and autonomic parameters, except for delta HF-RRI with lower values in the PMS group. The MS variant corrected for age, sex and Expanded Disability Status Scale (EDSS) score was an independent predictor of changes in the sympathovagal ratio as measured by HRV. Furthermore, a higher overall EDDS score was related to a higher sympathovagal ratio, lower parasympathetic parameters at rest, and decrease post-tilt changes of the sympathovagal ratio of sBP BPV. Autonomic imbalance is markedly altered in the MS patient group compared to control changes were most pronounced in the progressive variant of MS disease. The MS variant appeared to have a potential influence on cardiac autonomic imbalance at rest.

Altered splenic [89Zr]Zr-rituximab uptake in patients with interstitial lung disease not responding to rituximab: could this indicate a splenic immune-mediated mechanism?

Rituximab (RTX) for immune-mediated inflammatory disease (IMID) with interstitial pneumonitis (IP) results in non-response in about a third of patients for reasons not well understood. Complete peripheral B-cell depletion in IMID-IP does not seem to correlate with successful treatment outcome. A hypothesis is that splenic B cells might play a role in B-cell recovery and attraction of naïve B cells in non-responsive patients. The aim of this post hoc analysis of clinical trial data is to search for indicators in [⁸⁹Zr]Zr-rituximab PET/CT data from the spleen that might explain non-responsiveness. PET/CT data of 20 patients with IMID-IP, who were enrolled in a phase II trial and treated with RTX were analyzed. Clinical outcome was categorized into responders (RSP) and non-responders (NR) after 6 months of initial RTX by two independent pulmonologists. Patients were examined separately to search for associations between clinical outcome, splenic activity on PET/CT, lymphocyte counts and other biomarkers. Treatment failure was found in 6/20 patients (30%) while all patients exhibited B-cell depletion from the circulation. NR patients demonstrated significantly higher splenic activity than RSP patients (non-preload protocol: SUV 4.9±1.96 and SUV 2.3±1.08 respectively, P=0.025). No correlations between treatment outcome and serum lymphocyte subsets were found. Our findings suggest a potential splenic mechanism in IMID-IP patients non-responding to RTX and warrant further consideration and investigation.

Local Sympathectomy Promotes Anti-inflammatory Responses and Relief of Paclitaxel-induced Mechanical and Cold Allodynia in Mice

BACKGROUND

Patients undergoing cancer treatment often experience chemotherapy-induced neuropathic pain at their extremities, for which there is no U.S. Food and Drug Administration-approved drug. The authors hypothesized that local sympathetic blockade, which is used in the clinic to treat various pain conditions, can also be effective to treat chemotherapy-induced neuropathic pain.

METHODS

A local sympathectomy (i.e., cutting the ipsilateral gray rami entering the spinal nerves near the L3 and L4 dorsal root ganglia) was performed in mice receiving intraperitoneal injections every other day of the chemotherapeutic drug paclitaxel. Sympathectomy effects were then assessed in chemotherapy-induced pain-like behaviors (i.e., mechanical and cold allodynia) and neuroimmune and electrophysiologic responses.

RESULTS

Local microsympathectomy produced a fast recovery from mechanical allodynia (mean ± SD: sympathectomy vs. sham at day 5, 1.07 ± 0.34 g vs. 0.51 ± 0.17g, n = 5, P = 0.030 in male mice, and 1.08 ± 0.28 g vs. 0.62 ± 0.16 g, n = 5, P = 0.036 in female mice) and prevented the development of cold allodynia in both male and female mice after paclitaxel. Mechanistically, microsympathectomy induced transcriptional increases in dorsal root ganglia of macrophage markers and anti-inflammatory cytokines, such as the transforming growth factor-β. Accordingly, depletion of monocytes/macrophages and blockade of transforming growth factor-β signaling reversed the relief of mechanical allodynia by microsympathectomy. In particular, exogenous transforming growth factor-β was sufficient to relieve mechanical allodynia after paclitaxel (transforming growth factor-β 100 ng/site vs. vehicle at 3 h, 1.21 ± 0.34g vs. 0.53 ± 0.14 g, n = 5, P = 0.001 in male mice), and transforming growth factor-β signaling regulated neuronal activity in dorsal root ganglia.

CONCLUSIONS

Local sympathetic nerves control the progression of immune responses in dorsal root ganglia and pain-like behaviors in mice after paclitaxel, raising the possibility that clinical strategies already in use for local sympathetic blockade may also offer an effective treatment for patients experiencing chemotherapy-induced neuropathic pain.

Sympathetic function and markers of inflammation in well-controlled HIV

PURPOSE

HIV-associated autonomic neuropathy (HIV-AN) is common and may be associated with both sympathetic and parasympathetic dysfunction. Sympathetic nervous system (SNS) dysfunction occurs on a continuum of hyper-to hypo-adrenergic function, and may be a mediator between psychological stress and chronic inflammation. We sought to describe patterns of SNS dysfunction in people living with HIV, and to determine whether SNS dysfunction is associated with markers of systemic inflammation (focusing on IL-6 and TNF-α) and pain and anxiety.

METHODS

Forty-seven people with well-controlled HIV and without confounding medical conditions or medications completed the Medical Outcomes Survey (MOS-HIV), quantification of a panel of 41 plasma cytokines/chemokines, and a standardized, non-invasive autonomic reflex screen (ARS). Adrenergic baroreflex sensitivity (BRSA) was calculated from the ARS as a measure of SNS function.

RESULTS

Pain (46%) and anxiety (52%) were commonly reported on the MOS-HIV. BRSA was reduced in 30% of participants and elevated in 9% with the latter occurring only in participants with normal to mild HIV-AN. BRSA was significantly associated with IL-6, but not with TNF-α, pain or anxiety. Exploratory analyses also revealed positive associations of BRSA with numerous other cytokines with no significant inverse associations.

CONCLUSION

Higher BRSA, indicative of a more hyperadrenergic state, can be part of the spectrum of early HIV-AN, and may be associated with elevations in multiple cytokines including IL-6. These associations do not appear to be driven by stressors such as pain or anxiety.

Effect of rapamycin on repeated immobilization stress-induced immune alterations in the rat spleen

Chronic stress modulates immune system functions via neuroendocrine pathways. Rapamycin inhibits activity of immune cells through the mTOR signaling pathway. We investigated the effect of rapamycin (15 mg/kg, 3-times/week) on neuroimmune-endocrine system in the spleen of rats exposed to 42 cycles of 2-h immobilization. Rapamycin enhanced the activity of hypothalamic-pituitary-adrenocortical axis induced by stress exposure, prevented stress-induced expression of natural killer cell markers while reversed stress-evoked decline of Th2 immune response markers. Overall, our findings suggest that rapamycin may act on immune functions not only directly by inhibiting of mTOR in immune cells but also indirectly via modulation of neuroendocrine system.

The fatty acid amide hydrolase inhibitor URB597 modulates splenic catecholamines in chronically stressed female and male rats

The changes in sympathetic innervations in lymphoid organs could be a key factor in immune dysregulation. The endocannabinoid system has been shown to exhibit potent immunomodulatory effects that may differ between males and females, representing a potential therapeutic target for peripheral and central inflammatory disorders. Thus, in the present study, an examination was made of the effect of fatty acid amide hydrolase inhibitor URB597 treatment on splenic catecholamine content, synthesis, uptake and degradation in chronically unpredictably stressed (CUS) female and male rats. The results show that CUS increases anxiety-like behaviors and that URB597 had an anxiolytic effect on chronically stressed animals of both sexes. CUS induced the expression of plasma interleukin - 6 (IL-6), interleukin - 10 (IL-10) and IL-6 in the spleen, whereas the expression of IL-10 was reduced in the spleen of both sexes. URB597 treatment did not cause changes in IL-6 in plasma or the spleen, whereas it increased IL-10 in the spleen in CUS animals of both sexes. CUS caused a significant depletion of noradrenaline content in the spleen of female rats and a reduction in noradrenaline uptake in the spleen of female rats, while stressed males had a small but insignificant decrease of splenic noradrenaline levels and an enhanced uptake. The FAAH inhibitor URB597 enhances reduced noradrenaline content, affecting its uptake directly at the level of the spleen. It gives rise to the possibility that endocannabinoids exert a neurorestorative effect on the sympathetic nerve system and cell-mediated immune responses in the spleen of chronically stressed rats.

Organ System Crosstalk in Cardiometabolic Disease in the Age of Multimorbidity

The close association among cardiovascular, metabolic, and kidney diseases suggests a common pathological basis and significant interaction among these diseases. Metabolic syndrome and cardiorenal syndrome are two examples that exemplify the interlinked development of disease or dysfunction in two or more organs. Recent studies have been sorting out the mechanisms responsible for the crosstalk among the organs comprising the cardiovascular, metabolic, and renal systems, including heart-kidney and adipose-liver signaling, among many others. However, it is also becoming clear that this crosstalk is not limited to just pairs of organs, and in addition to organ-organ crosstalk, there are also organ-system and organ-body interactions. For instance, heart failure broadly impacts various organs and systems, including the kidney, liver, lung, and nervous system. Conversely, systemic dysregulation of metabolism, immunity, and nervous system activity greatly affects heart failure development and prognosis. This is particularly noteworthy, as more and more patients present with two or more coexisting chronic diseases or conditions (multimorbidity) due in part to the aging of society. Advances in treatment also contribute to the increase in multimorbidity, as exemplified by cardiovascular disease in cancer survivors. To understand the mechanisms underlying the increasing burden of multimorbidity, it is vital to elucidate the multilevel crosstalk and communication within the body at the levels of organ systems, tissues, and cells. In this article, we focus on chronic inflammation as a key common pathological basis of cardiovascular and metabolic diseases, and discuss emerging mechanisms that drive chronic inflammation in the context of multimorbidity.

Autonomic nervous system and inflammation interaction in endometriosis-associated pain

Endometriosis is a chronic inflammatory disease. Pain is the most common symptom in endometriosis. Endometriosis-associated pain is caused by inflammation, and is related to aberrant innervation. Although the specific mechanism between endometriosis-associated pain and the interaction of aberrant innervation and inflammation remains unclear, many studies have confirmed certain correlations between them. In addition, we found that some chronic inflammatory autoimmune diseases (AIDs) such as inflammatory bowel disease (IBD) and rheumatoid arthritis (RA) share similar characteristics: the changes in dysregulation of inflammatory factors as well as the function and innervation of the autonomic nervous system (ANS). The mechanisms underlying the interaction between the ANS and inflammation have provided new advances among these disorders. Therefore, the purpose of this review is to compare the changes in inflammation and ANS in endometriosis, IBD, and RA; and to explore the role and possible mechanism of sympathetic and parasympathetic nerves in endometriosis-associated inflammation by referring to IBD and RA studies to provide some reference for further endometriosis research and treatment.

Exploration of the Molecular Mechanism of FUZI (Aconiti Lateralis Radix Praeparata) in Allergic Rhinitis Treatment Based on Network Pharmacology

FUZI (Aconiti Lateralis Radix Praeparata) is a traditional Chinese medicine herb used extensively for nourishing yang (regarded as the positive, male universal force), which is critical in treatment of allergic rhinitis. In this paper, FUZI was explored based on network pharmacology. The active components of FUZI were screened out, its protein targets were assessed, and the protein interaction network map was built with the differential protein of allergic rhinitis, as an attempt to determine the critical targets of FUZI for treating allergic rhinitis. Subsequently, DAVID was employed to explore the biological function and pathway enrichment to determine the biological pathway of FUZI for treating allergic rhinitis.

As suggested by the results, FUZI is likely to affect the inhibition of inflammation and the regulation of immunity, probably reducing the incidence of allergic rhinitis, or alleviating nasal discomfort attributed to allergic inflammation. The targets and pathways of FUZI for treating allergic rhinitis assessed by network pharmacology provided a direction for our subsequent studies and may be a novel therapeutic target.

The sympathetic nervous system in acute kidney injury

Acute kidney injury (AKI) is frequently accompanied by activation of the sympathetic nervous system (SNS). This may result from pre-exisiting chronic diseases associated with sympathetic activation prior to AKI or it may be induced by stressors that ultimately lead to AKI such as endotoxins and arterial hypotension in circulatory shock. Conversely, sympathetic activation may also result from acute renal injury. Focusing on studies in experimental renal ischaemia and reperfusion (IR), this review summarizes the current knowledge on how the SNS is activated in IR-induced AKI and on the consequences of sympathetic activation for the development of acute renal damage. Experimental studies show beneficial effects of sympathoinhibitory interventions on renal structure and function in response to IR. However, few clinical trials obtained in scenarios that correspond to experimental IR, namely major elective surgery, showed that peri-operative treatment with centrally acting sympatholytics reduced the incidence of AKI. Apparently, discrepant findings on how sympathetic activation influences renal responses to acute IR-induced injury are discussed and future areas of research in this field are identified.

Proinflammatory α-Adrenergic Neuronal Regulation of Splenic IFN-γ, IL-6, and TGF-β of Mice from Day 15 onwards in Arthritis

INTRODUCTION

In arthritic mice, a sympathetic influence is proinflammatory from the time point of immunization until the onset of disease (days 0-32), but reasons are unknown. Disruption of the major anti-inflammatory pathway through Gαs-coupled receptors probably play a role. For example, noradrenaline cannot operate via anti-inflammatory β2-adrenoceptors but through proinflammatory α1/2-ad-renoceptors. This might happen, first, through a loss of sympathetic nerve fibers in inflamed tissue with low neurotransmitter levels (noradrenaline only binds to high-affinity α-adrenoceptors) and, second, through an alteration in G-protein receptor coupling with a predominance of α-adrenergic signaling. We hypothesized that both mechanisms play a role in the course of collagen type II-induced arthritis (CIA) in the spleen in mice.

METHODS

In CIA mice, nerve fiber density in the spleen was quantified by immunohistochemistry techniques. The functional impact of sympathetic nerve fibers in the spleen was studied by a micro-superfusion technique of spleen slices with a focus on the secretion of IFN-γ and IL-6 (proinflammatory) and TGF-β (anti-inflammatory).

RESULTS

During CIA, sympathetic nerve fibers get increasingly lost from day14 until day 55 after immunization. The influence of electrically released noradrenaline diminishes in the course of arthritis. At all investigated time points (days 14, 32, and 55), only proinflammatory neuronal α-adrenergic effects on cytokine secretion were demonstrated (i.e., stimulation of IFN-γ and IL-6 and inhibition of TGF-β).

CONCLUSION

Sympathetic nerve fibers are rapidly lost in the spleen, and only proinflammatory α-adrenergic neuronal regulation of cytokine secretion takes place throughout the course of arthritis. These results support a predominance of a proinflammatory α-adrenergic sympathetic influence in arthritis.

Splenic artery denervation: target micro-anatomy, feasibility, and early preclinical experience

This study sought to evaluate perisplenic artery nerve distribution and the feasibility of splenic artery denervation (SDN). The NEXION radiofrequency catheter was used to perform SDN in healthy and inflammatory arthritis pigs. Splenic artery anatomy, nerve distribution, and splenic norepinephrine (NEPI) levels were evaluated before and after SDN. Perisplenic artery nerves were primarily distributed within 2.5 mm of the arterial lumen and were largely sympathetic on the basis of tyrosine hydroxylase expression. The pancreas, tended to be circumferentially positioned around the proximal splenic artery, typically >2.5 mm from the lumen, ensuring that most of the nerves could be targeted without affecting this sensitive organ. The mid segment of the splenic artery was relatively free of contact with the adjacent pancreas. Splenic NEPI levels and nerve abundance followed a decreasing gradient from the proximal to distal splenic artery. SDN resulted in significant reductions in splenic NEPI levels at day 14 (60.7%, P = 0.024) in naïve pigs and day 45 (100%, P = 0.001) in inflammatory arthritis pigs. There was no significant effect of SDN on joint soft tissue injury or circulating inflammatory markers in the inflammatory arthritis model. The majority of perisplenic arterial nerves are within close proximity of the lumen and are primarily sympathetic efferent fibers. Nerves in the mid-segment may be the preferred SDN target given their proximity to the artery and paucity of periarterial off-target organs. SDN appears safe and effective at reducing splenic NEPI levels.

Toward the Existence of a Sympathetic Neuroplasticity Adaptive Mechanism Influencing the Immune Response. A Hypothetical View-Part II

In the preceding work, a hypothesis on the existence of a specific neural plasticity program from sympathetic fibers innervating secondary lymphoid organs was introduced. This proposed adaptive mechanism would involve segmental retraction and degeneration of noradrenergic terminals during the immune system (IS) activation followed by regeneration once the IS returns to the steady-state. Starting from such view, this second part presents clinical and experimental evidence allowing to envision that this sympathetic neural plasticity mechanism is also operative on inflamed non-lymphoid peripheral tissues. Importantly, the sympathetic nervous system regulates most of the physiological bodily functions, ranging from cardiovascular, respiratory and gastro-intestinal functions to endocrine and metabolic ones, among others. Thus, it seems sensible to think that compensatory programs should be put into place during inflammation in non-lymphoid tissues as well, to avoid the possible detrimental consequences of a sympathetic blockade. Nevertheless, in many pathological scenarios like severe sepsis, chronic inflammatory diseases, or maladaptive immune responses, such compensatory programs against noradrenergic transmission impairment would fail to develop. This would lead to a manifest sympathetic dysfunction in the above-mentioned settings, partly accounting for their underlying pathophysiological basis; which is also discussed. The physiological/teleological significance for the whole neural plasticity process is postulated, as well.

Identification of candidate genes and miRNAs associated with neuropathic pain induced by spared nerve injury

Neuropathic pain (NP) is a complex, chronic pain condition caused by injury or dysfunction affecting the somatosensory nervous system. This study aimed to identify crucial genes and miRNAs involved in NP. Microarray data (access number GSE91396) were downloaded from the Gene Expression Omnibus (GEO). Murine RNA-seq samples from three brain regions [nucleus accumbens, (NAc); medial prefrontal cortex, (mPFC) and periaqueductal gray, (PAG)] were compared between the spared nerve injury (SNI) model and a sham surgery. After data normalization, differentially expressed RNAs were screened using the limma package and functional enrichment analysis was performed with Database for Annotation, Visualization and Integrated Discovery. The microRNA (miRNA/miR)-mRNA regulatory network and miRNA-target gene-pathway regulatory network were constructed using Cytoscape software. A total of 2,776 differentially expressed RNAs (219 miRNAs and 2,557 mRNAs) were identified in the SNI model compared with the sham surgery group. A total of two important modules (red and turquoise module) were found to be related to NP using weighed gene co-expression network analysis (WGCNA) for the 2,325 common differentially expressed RNAs in three brain regions. The differentially expressed genes (DEGs) in the miRNA-mRNA regulatory network were significantly enriched in 21 Gene Ontology terms and five pathways. A total of four important DEGs (CXCR2, IL12B, TNFSF8 and GRK1) and five miRNAs (miR-208a-5p, miR-7688-3p, miR-344f-3p, miR-135b-3p and miR-135a-2-3p) were revealed according to the miRNA-target gene-pathway regulatory network to be related to NP. Four important DEGs (CXCR2, IL12B, TNFSF8 and GRK1) and five miRNAs (miR-208a-5p, miR-7688-3p, miR-344f-3p, miR-135b-3p and miR-135a-2-3p) were differentially expressed in SNI, indicating their plausible roles in NP pathogenesis.

Neuromodulation of metabolic functions: from pharmaceuticals to bioelectronics to biocircuits

Neuromodulation of central and peripheral neural circuitry brings together neurobiologists and neural engineers to develop advanced neural interfaces to decode and recapitulate the information encoded in the nervous system. Dysfunctional neuronal networks contribute not only to the pathophysiology of neurological diseases, but also to numerous metabolic disorders. Many regions of the central nervous system (CNS), especially within the hypothalamus, regulate metabolism. Recent evidence has linked obesity and diabetes to hyperactive or dysregulated autonomic nervous system (ANS) activity. Neural regulation of metabolic functions provides access to control pathology through neuromodulation. Metabolism is defined as cellular events that involve catabolic and/or anabolic processes, including control of systemic metabolic functions, as well as cellular signaling pathways, such as cytokine release by immune cells. Therefore, neuromodulation to control metabolic functions can be used to target metabolic diseases, such as diabetes and chronic inflammatory diseases. Better understanding of neurometabolic circuitry will allow for targeted stimulation to modulate metabolic functions. Within the broad category of metabolic functions, cellular signaling, including the production and release of cytokines and other immunological processes, is regulated by both the CNS and ANS. Neural innervations of metabolic (e.g. pancreas) and immunologic (e.g. spleen) organs have been understood for over a century, however, it is only now becoming possible to decode the neuronal information to enable exogenous controls of these systems. Future interventions taking advantage of this progress will enable scientists, engineering and medical doctors to more effectively treat metabolic diseases.

Immunohistochemical analysis of the mouse celiac ganglion: An integrative relay station of the peripheral nervous system

Celiac ganglia are important sites of signal integration and transduction. Their complex neurochemical anatomy has been studied extensively in guinea pigs but not in mice. The goal of this study was to provide detailed neurochemical characterization of mouse celiac ganglia and noradrenergic nerves in two target tissues, spleen and stomach. A vast majority of mouse celiac neurons express a noradrenergic phenotype, which includes tyrosine hydroxylase (TH), vesicular monoamine transporter 2, and the norepinephrine transporter. Over 80% of these neuron also express neuropeptide Y (NPY), and this coexpression is maintained by dissociated neurons in culture. Likewise, TH and NPY were colocalized in noradrenergic nerves throughout the spleen and in stomach blood vessels. Somatostatin was not detected in principal neurons but did occur in small, TH-negative cells presumed to be interneurons and in a few varicose nerve fibers. Cholinergic nerves provided the most abundant input to the ganglia, and small percentages of these also contained nitric oxide synthase or vasoactive intestinal polypeptide. A low-to-moderate density of nerves also stained separately for the latter markers. Additionally, nerve bundles and varicose nerve fibers containing the sensory neuropeptides, calcitonin gene-related polypeptide, and substance P, occurred at variable density throughout the ganglia. Collectively, these findings demonstrate that principal neurons of mouse celiac ganglia have less neurochemical diversity than reported for guinea pig and other species but receive input from nerves expressing an array of neurochemical markers. This profile suggests celiac neurons integrate input from many sources to influence target tissues by releasing primarily norepinephrine and NPY.

Role of the End-Point Mediators of Sympathoadrenal and Sympathoneural Stress Axes in the Pathogenesis of Experimental Autoimmune Encephalomyelitis and Multiple Sclerosis

The role of stress effector systems in the initiation and progression of multiple sclerosis (MS) and experimental autoimmune encephalomyelitis (EAE), the most commonly used experimental model of MS, has strongly been suggested. To corroborate this notion, alterations in activity of the sympathoadrenal and sympathoneural axes of sympathoadrenal system (a major communication pathway between the central nervous system and the immune system), mirrored in altered release of their end-point mediators (adrenaline and noradrenaline, respectively), are shown to precede (in MS) and/or occur during development of MS and EAE in response to immune cell activation (in early phase of disease) and disease-related damage of sympathoadrenal system neurons and their projections (in late phase of disease). To add to the complexity, innate immunity cells and T-lymphocytes synthesize noradrenaline that may be implicated in a local autocrine/paracrine self-amplifying feed-forward loop to enhance myeloid-cell synthesis of proinflammatory cytokines and inflammatory injury. Furthermore, experimental manipulations targeting noradrenaline/adrenaline action are shown to influence clinical outcome of EAE, in a disease phase-specific manner. This is partly related to the fact that virtually all types of cells involved in the instigation and progression of autoimmune inflammation and target tissue damage in EAE/MS express functional adrenoceptors. Although catecholamines exert majority of immunomodulatory effects through β₂-adrenoceptor, a role for α-adrenoceptors in EAE pathogenesis has also been indicated. In this review, we summarize all aforementioned aspects of immunopathogenetic action of catecholamines in EAE/MS as possibly important for designing new strategies targeting their action to prevent/mitigate autoimmune neuroinflammation and tissue damage.