Rethinking inflammation: neural circuits in the regulation of immunity

Small Heat Shock Proteins, Amyloid Fibrils, and Nicotine Stimulate a Common Immune Suppressive Pathway with Implications for Future Therapies

The α7 nicotinic acetylcholine receptor (α7nAChR) is central to the anti-inflammatory function of the vagus nerve in a physiological mechanism termed the inflammatory reflex. Studies on the inflammatory reflex have been instrumental for the current development of the field of bioelectronic medicine. An independent investigation of the biological role of αB-crystallin (HspB5), the most abundant gene transcript present in active multiple sclerosis lesions in human brains, also led to α7nAChR. Induction of experimental autoimmune encephalomyelitis (EAE) in HspB5^-/- mice results in greater paralytic signs, increased levels of proinflammatory cytokines, and T-lymphocyte activation relative to wild-type animals. Administration of HspB5 was therapeutic in animal models of multiple sclerosis, retinal and cardiac ischemia, and stroke. Structure-activity studies established that residues 73-92 were as potent as the parent protein, but only when it formed amyloid fibrils. Amyloid fibrils and small heat shock proteins (sHsps) selectively bound α7nAChR on peritoneal macrophages (MΦs) and B lymphocytes, converting the MΦs to an immune suppressive phenotype and mobilizing the migration of both cell types from the peritoneum to secondary lymph organs. Here, we review multiple aspects of this work, which may be of interest for developing future therapeutic approaches for multiple sclerosis and other disorders.

Therapeutic ultrasound attenuates DSS-induced colitis through the cholinergic anti-inflammatory pathway

BACKGROUND

Ulcerative Colitis (UC) is an Inflammatory Bowel Disease (IBD) characterized by uncontrolled immune response, diarrhoea, weight loss and bloody stools, where sustained remission is not currently achievable. Dextran Sulphate Sodium (DSS)-induced colitis is an animal model that closely mimics human UC. Ultrasound (US) has been shown to prevent experimental acute kidney injury through vagus nerve (VN) stimulation and activation of the cholinergic anti-inflammatory pathway (CAIP). Since IBD patients may present dysfunctional VN activity, our aim was to determine the effects of therapeutic ultrasound (TUS) in DSS-induced colitis.

METHODS

Acute colitis was induced by 2% DSS in drinking water for 7 days and TUS was administered to the abdominal area for 7 min/day from days 4-10. Clinical symptoms were analysed, and biological samples were collected for proteomics, macroscopic and microscopic analysis, flow cytometry and immunohistochemistry.

FINDINGS

TUS attenuated colitis by reducing clinical scores, colon shortening and histological damage, inducing proteomic tolerogenic response in the gut during the injury phase and early recovery of experimental colitis. TUS did not improve clinical and pathological outcomes in splenectomised mice, while α7nAChR (α7 nicotinic acetylcholine receptor - indicator of CAIP involvement) knockout animals presented with disease worsening. Increased levels of colonic F4/80+α7nAChR+ macrophages in wild type mice suggest CAIP activation.

INTERPRETATION

These results indicate TUS improved DSS-induced colitis through stimulation of the splenic nerve along with possible contribution by VN with CAIP activation. FUND: Intramural Research Programs of the Clinical Centre, the National Institute of Biomedical Imaging and Bioengineering at the NIH and CAPES/Brazil.

Immunomodulatory role of non-neuronal cholinergic signaling in myocardial injury

Whereas prior studies have demonstrated an important immunomodulatory role for the neuronal cholinergic system in the heart, the role of the non-neuronal cholinergic system is not well understood. To address the immunomodulatory role of the non-neuronal cholinergic system in the heart we used a previously validated diphtheria toxin (DT)-induced cardiomyocyte ablation model (Rosa26-DTMlc2v-Cre mice). DT-injected Rosa26-DTMlc2v-Cre mice were treated with diluent or Pyridostigmine Bromide (PYR), a reversible cholinesterase inhibitor. PYR treatment resulted in increased survival and decreased numbers of MHC-IIlowCCR2+ macrophages in DT-injected Rosa26-DTMlc2v-Cre mice compared to diluent treated Rosa26-DTMlc2v-Cre mice. Importantly, the expression of CCL2/7 mRNA and protein was reduced in the hearts of PYR-treated mice. Backcrossing Rosa26-DTMlc2v-Cre mice with a transgenic mouse line (Chat-ChR2) that constitutively overexpresses the vesicular acetylcholine transporter (VAChT) resulted in decreased expression of Ccl2/7 mRNA and decreased numbers of CD68+ cells in DT-injured Rosa26-DTMlc2v-Cre/Chat-ChR2 mouse hearts, consistent with the pharmacologic studies with PYR. In vitro studies with cultures of LPS-stimulated peritoneal macrophages revealed a concentration-dependent reduction in CCL2 secretion following stimulation with ACh, nicotine and muscarine. Viewed together, these findings reveal a previously unappreciated immunomodulatory role for the non-neuronal cholinergic system in regulating homeostatic responses in the heart following tissue injury.

Nicotine Attenuates Osteoarthritis Pain and Matrix Metalloproteinase-9 Expression via the α7 Nicotinic Acetylcholine Receptor

Osteoarthritis (OA) is a degenerative joint disease that causes chronic disability among the elderly. Despite recent advances in symptomatic management of OA by pharmacological and surgical approaches, there remains a lack of optimal approaches to manage inflammation in the joints, which causes cartilage degradation and pain. In this study, we investigated the efficacy and underlying mechanisms of nicotine exposure in attenuating joint inflammation, cartilage degradation, and pain in a mouse model of OA. A mouse model of OA was induced by injection of monosodium iodoacetate into the knee joint. Cell culture models were also used to study the efficacy and underlying mechanisms of nicotine treatment in attenuating symptoms of OA. Nicotine treatment reduced mechanical allodynia, cartilage degradation, and the upregulation of matrix metalloproteinase-9 (MMP-9), a hallmark of joint inflammation in OA, in mice treated with monosodium iodoacetate. The effects of nicotine were abolished by the selective α7 nicotinic acetylcholine receptor (nAChR) blocker, methyllycaconitine . In RAW264.7 cells and murine primary bone marrow-derived macrophages, nicotine significantly inhibited MMP-9 production induced by LPS. In addition, nicotine significantly enhanced PI3K/Akt and inhibited NF-κB translocation from the cytosol to the nucleus in an α7-nAChR-dependent manner, suggesting that nicotine acts on α7-nAChRs to inhibit MMP-9 production by macrophages through modulation of the PI3K/Akt-NF-κB pathway. Our results provide novel evidence that nicotine can attenuate joint inflammation and pain in experimental OA via α7-nAChRs. α7-nAChR could thus serve as a highly promising target to manage joint inflammation and pain in OA.

Splenic Blood Flow Increases after Hypothermic Stimulus (Cold Pressor Test): A Perfusion Magnetic Resonance Study

The Cold Pressor Test (CPT) is a novel diagnostic strategy to noninvasively assess the myocardial microvascular endothelial-dependent function using perfusion magnetic resonance imaging (MRI). Spleen perfusion is modulated by a complex combination of several mechanisms involving the autonomic nervous system and vasoactive mediators release. In this context, the effects of cold temperature on splenic blood flow (SBF) still need to be clarified. Ten healthy subjects were studied by MRI. MRI protocol included the acquisition of GRE T1-weighted sequence (“first pass perfusion”) during gadolinium administration (0.1mmol/kg of Gd-DOTA at flow of 3.0 ml/s), at rest and after CPT. Myocardial blood flow (MBF) and SBF were measured by applying Fermi function deconvolution, using the blood pool input function sampled from the left ventricle cavity. MBF and SBF values after performing CPT were significantly higher than rest values (SBF at rest: 0.65 ± 0.15 ml/min/g Vs. SBF after CPT: 0.90 ± 0.14 ml/min/g, p: <0.001; MBF at rest: 0.90 ± 0.068 ml/min/g Vs. MBF after CPT: 1.22 ± 0.098 ml/min/g, p<0.005). Both SBF and MBF increased in all patients during the CPT. In particular, the CPT-induced increase was 43% ± 29% for SBF and 36.5% ± 17% for MBF. CPT increases SBF in normal subjects. The characterization of a standard perfusion response to cold might allow the use of the spleen as reference marker for the adequacy of cold stimulation during myocardial perfusion MRI.

Which heart rate variability index is an independent predictor of mortality in cirrhosis?

BACKGROUND

Liver cirrhosis is associated with reduced heart rate variability (HRV), which indicates impaired integrity of cardiovascular control in this patient population. There are several different indices for HRV quantification. The present study was designed to: 1) determine which of the HRV indices is best at predicting mortality in patients with cirrhosis; 2) verify if such ability to predict mortality is independent of the severity of hepatic failure.

METHODS

Ten minutes electrocardiogram was recorded in 74 patients with cirrhosis. Heart rate fluctuations were quantified using statistical, geometrical and non-linear analysis. The patients were followed-up for 18months and information was collected on the occurrence of death/liver transplantation.

RESULTS

During the follow-up period, 24 patients (32%) died or were transplanted for hepatic decompensation. Cox's regression analysis showed that SDNN (total HRV), cSDNN (corrected SDNN), SD1 (short-term HRV), SD2 (long-terms HRV) and spectral indices could predict survival in these patients. However, only SD2 and cSDNN were shown to be independent of MELD in predicting survival. The prognostic value of HRV indices was independent of age, gender, use of beta blockers, and the aetiology of liver disease.

CONCLUSION

Two HRV indices were identified that could predict mortality in patients with cirrhosis, independently of MELD. These indices are potentially useful tools for survival prediction.

From Probiotics to Psychobiotics: Live Beneficial Bacteria Which Act on the Brain-Gut Axis

There is an important relationship between probiotics, psychobiotics and cognitive and behavioral processes, which include neurological, metabolic, hormonal and immunological signaling pathways; the alteration in these systems may cause alterations in behavior (mood) and cognitive level (learning and memory). Psychobiotics have been considered key elements in affective disorders and the immune system, in addition to their effect encompassing the regulation of neuroimmune regulation and control axes (the hypothalamic-pituitary-adrenal axis or HPA, the sympathetic-adrenal-medullary axis or SAM and the inflammatory reflex) in diseases of the nervous system. The aim of this review is to summarize the recent findings about psychobiotics, the brain-gut axis and the immune system. The review focuses on a very new and interesting field that relates the microbiota of the intestine with diseases of the nervous system and its possible treatment, in neuroimmunomodulation area. Indeed, although probiotic bacteria will be concentrated after ingestion, mainly in the intestinal epithelium (where they provide the host with essential nutrients and modulation of the immune system), they may also produce neuroactive substances which act on the brain-gut axis.

Investigational treatment of rheumatoid arthritis with a vibrotactile device applied to the external ear

Background

Rheumatoid arthritis (RA) is a chronic and debilitating inflammatory disease characterized by extensive joint tissue inflammation. Implantable bioelectronic devices targeting the inflammatory reflex reduce TNF production and inflammation in preclinical models of inflammatory disease, and in patients with RA and Crohn’s disease. Here, we assessed the effect of applying a vibrotactile device to the cymba concha of the external ear on inflammatory responses in healthy subjects, as well as its effect on disease activity in RA patients.

Methods

Six healthy subjects received vibrotactile treatment at the cymba concha, and TNF production was analyzed at different time points post-stimulation. In a separate study, nineteen healthy subjects were enrolled in a randomized cross-over study, and effects of vibrotactile treatment at either the cymba concha or gastrocnemius on cytokine levels were assessed. In addition, the clinical efficacy of vibrotactile treatment on disease activity in RA was assessed in nine patients with RA in a prospective interventional study.

Results

Vibrotactile treatment at the cymba concha reduced TNF levels, and the suppressive effect persisted up to 24 h. In the cross-over study with 19 healthy subjects, vibrotactile treatment at the cymba concha but not at the gastrocnemius significantly reduced TNF, IL-1β, and IL-6 levels compared to pre-treatment baseline (TNF p < 0.05, IL-6 p < 0.01, IL-1β p < 0.001). In healthy subjects, vibrotactile treatment at the cymba concha inhibited TNF by 80%, IL-6 by 73%, and IL-1β by 50% as compared to pre-treatment baseline levels. In RA patients, a significant decrease in DAS28-CRP scores was observed two days post-vibrotactile stimulation at the cymba concha (DAS28-CRP score pre-treatment = 4.19 ± 0.33 vs post-treatment = 3.12 ± 0.25, p < 0.05). Disease activity remained significantly reduced 7 days following vibrotactile treatment (DAS28-CRP score 7 days post-treatment = 2.79 ± 0.21, p < 0.01). In addition, a persistent improvement in visual analogue scale scores, a patient derived measure of global health assessment, was observed in RA patients following vibrotactile treatment.

Conclusion

Application of a vibrotactile device to the cymba concha inhibits peripheral blood production of TNF, IL-1β, and IL-6 in healthy subjects, and attenuates systemic inflammatory responses in RA patients.

Trial registrations

ClinicalTrials.gov Identifier: NCT01569789 and NCT00859859. The AMC trial conducted in The Netherlands does not have a ClinicalTrials.gov Identifier.

Innervation of cervical carcinoma is mediated by cancer-derived exosomes

OBJECTIVE

Recently, our laboratory identified sensory innervation within head and neck squamous cell carcinomas (HNSCCs) and subsequently defined a mechanism whereby HNSCCs promote their own innervation via the release of exosomes that stimulate neurite outgrowth. Interestingly, we noted that exosomes from human papillomavirus (HPV)-positive cell lines were more effective at promoting neurite outgrowth than those from HPV-negative cell lines. As nearly all cervical tumors are HPV-positive, we hypothesized that these findings would extend to cervical cancer.

METHODS

We use an in vitro assay with PC12 cells to quantify the axonogenic potential of cervical cancer exosomes. PC12 cells are treated with cancer-derived exosomes, stained with the pan-neuronal marker (β-III tubulin) and the number of neurites quantified. To assess innervation in cervical cancer, we immunohistochemically stained cervical cancer patient samples for β-III tubulin and TRPV1 (sensory marker) and compared the staining to normal cervix.

RESULTS

Here, we show the presence of sensory nerves within human cervical tumors. Additionally, we show that exosomes derived from HPV-positive cervical cancer cell lines effectively stimulate neurite outgrowth.

CONCLUSIONS

These data identify sensory nerves as components of the cervical cancer microenvironment and suggest that tumor- derived exosomes promote their recruitment.

Psychological Stress and Mitochondria: A Conceptual Framework

BACKGROUND

The integration of biological, psychological, and social factors in medicine has benefited from increasingly precise stress response biomarkers. Mitochondria, a subcellular organelle with its own genome, produce the energy required for life and generate signals that enable stress adaptation. An emerging concept proposes that mitochondria sense, integrate, and transduce psychosocial and behavioral factors into cellular and molecular modifications. Mitochondrial signaling might in turn contribute to the biological embedding of psychological states.

METHODS

A narrative literature review was conducted to evaluate evidence supporting this model implicating mitochondria in the stress response, and its implementation in behavioral and psychosomatic medicine.

RESULTS

Chronically, psychological stress induces metabolic and neuroendocrine mediators that cause structural and functional recalibrations of mitochondria, which constitutes mitochondrial allostatic load. Clinically, primary mitochondrial defects affect the brain, the endocrine system, and the immune systems that play a role in psychosomatic processes, suggesting a shared underlying mechanistic basis. Mitochondrial function and dysfunction also contribute to systemic physiological regulation through the release of mitokines and other metabolites. At the cellular level, mitochondrial signaling influences gene expression and epigenetic modifications, and modulates the rate of cellular aging.

CONCLUSIONS

This evidence suggests that mitochondrial allostatic load represents a potential subcellular mechanism for transducing psychosocial experiences and the resulting emotional responses-both adverse and positive-into clinically meaningful biological and physiological changes. The associated article in this issue of Psychosomatic Medicine presents a systematic review of the effects of psychological stress on mitochondria. Integrating mitochondria into biobehavioral and psychosomatic research opens new possibilities to investigate how psychosocial factors influence human health and well-being across the life-span.

Modulating the Inflammatory Reflex in Rats Using Low-Intensity Focused Ultrasound Stimulation of the Vagus Nerve

Tumor necrosis factor α (TNF-α) is linked to several chronic inflammatory diseases. Electrical vagus nerve stimulation reduces serum TNF-α levels but may cause chronic nerve damage and requires surgery. Alternatively, we proposed focused ultrasound stimulation of the vagus nerve (uVNS), which can be applied non-invasively. In this study, we induced an inflammatory response in rats using lipopolysaccharides (LPS) and collected blood to analyze the effects of uVNS on cytokine concentrations. We applied one or three 5-min pulsed focused ultrasound stimulation treatments to the vagus nerve (250 kHz, I_SPPA = 3 W/cm²). Animals receiving a single ultrasound application had an average reduction in TNF-α levels of 19%, similar to the 16% reduction observed in electrically stimulated animals. With multiple applications, uVNS therapy statistically reduced serum TNF-α levels by 73% compared with control animals without any observed damage to the nerve. These findings suggest that uVNS is a suitable way to attenuate TNF-α levels.

Propranolol and ascorbic acid in control of fibrodysplasia ossificans progressiva flare-ups due to accidental falls

Fibrodysplasia ossificans progressiva (FOP) is a rare, intractable and devastating genetic connective tissue disorder characterized by progressive ectopic ossification in the soft tissues and skeleton. Three patients, one teenage girl (P1), one male adult (P2) and one male child (P3), were studied and treated with FOPCON (combined formulation of 14 mg of propranolol and 250 mg of ascorbic acid), given three times per day. P1 started treatment in March 2012, P2 in October 2012 and P3 in July 2015. The clinical follow-up of these three patients, before initiating treatment with FOPCON, showed that FOP flare-ups used to occur frequently and that under FOPCON therapy, none of these patients had flare-ups. The striking feature of this treatment with FOPCON, is that, all three cases suffered accidental falls with documented injures until complete healing and that where major flare-ups should occur, injures or sequels, there was none. The present clinical observation shows that ascorbic acid plus the nonspecific beta blocker propranolol can be effectively useful, when administered previously and continually, in the prophylaxis of FOP flare-ups, especially for accidental falls. In this regard, FOPCON could be a prophylactic aid in cases of surgery of patients with FOP, hoping that it may benefit patients from having the severe sequels, characteristic of heterotopic bone formation. All three patients reported, to date, they no longer had flare-ups nor heterotopic ossification and showed normal scar healing.

In Vivo Effects of Neostigmine and Physostigmine on Neutrophil Functions and Evaluation of Acetylcholinesterase and Butyrylcholinesterase as Inflammatory Markers during Experimental Sepsis in Rats

Introduction

Recent studies have shown that acetylcholinesterase (AChE) and butyrylcholinesterase (BChE) may serve as important diagnostic and therapeutic targets in sepsis. Since polymorphonuclear neutrophils (PMNs) play a pivotal role in the early phase of sepsis, we evaluated the potential therapeutic effects of cholinesterase inhibitors on PMN functions during cecal ligation and puncture- (CLP-) induced sepsis and investigated the roles of AChE and BChE as inflammatory markers under standardized experimental conditions.

Methods

Sham surgery or CLP was performed in male Wistar rats (n = 60). Animals were randomized into four groups: physostigmine, 100 μg/kg; neostigmine, 75 μg/kg; 0.9% saline (control group); and sham group, each applied four times over 24 h. The levels of reactive oxygen species (ROS) production and CD11b/CD62l expression were quantified by flow cytometry at t = 0, 6, 15, 20, and 24 h. Blood gas analysis as well as AChE and BChE activity levels was measured by validated point-of-care measurements. Clinical scores and survival times were determined.

Results

CLP induced a significant increase in ROS production and CD11b upregulation by rat PMNs. Treatment with physostigmine or neostigmine significantly reduced ROS production and CD11b upregulation by PMNs 20 h after CLP induction. In physostigmine-treated animals, survival times were significantly improved compared to the control animals, but not in neostigmine-treated animals. While AChE activity significantly decreased in the control animals at t > 6 h, AChE activity did not change in the sham group. BChE activity decreased at t > 20 h in the control animals.

Conclusion

While AChE activity may serve as an acute inflammatory marker, BChE activity shows a delayed decrease. Administration of centrally acting physostigmine in CLP-induced sepsis in rats has protective effects on PMN functions and improves survival times, which may be of interest in clinical practice.

Perioperative Inflammation and Its Modulation by Anesthetics

Surgery and other invasive procedures, which are routinely performed during general anesthesia, may induce an inflammatory response in the patient. This inflammatory response is an inherent answer of the body to the intervention and can be both beneficial and potentially harmful. The immune system represents a unique evolutionary achievement equipping higher organisms with an effective defense mechanism against exogenous pathogens. However, not only bacteria might evoke an immune response but also other noninfectious stimuli like the surgical trauma or mechanical ventilation may induce an inflammatory response of varying degree. In these cases, the immune system activation is not always beneficial for the patients and might carry the risk of concomitant, harmful effects on host cells, tissues, or even whole organ systems. Research over the past decades has contributed substantial information in which ways surgical patients may be affected by inflammatory reactions. Modulations of the patient's immune system may be evoked by the use of anesthetic agents, the nature of surgical trauma and the use of any supportive therapy during the perioperative period. The effects on the patient may be manifold, including various proinflammatory effects. This review focuses on the causes and effects of inflammation in the perioperative period. In addition, we also highlight possible approaches by which inflammation in the perioperative may be modulated in the future.

Adenylyl Cyclase 6 Mediates Inhibition of TNF in the Inflammatory Reflex

Macrophage cytokine production is regulated by neural signals, for example in the inflammatory reflex. Signals in the vagus and splenic nerves are relayed by choline acetyltransferase⁺ T cells that release acetylcholine, the cognate ligand for alpha7 nicotinic acetylcholine subunit-containing receptors (α7nAChR), and suppress TNF release in macrophages. Here, we observed that electrical vagus nerve stimulation with a duration of 0.1–60 s significantly reduced systemic TNF release in experimental endotoxemia. This suppression of TNF was sustained for more than 24 h, but abolished in mice deficient in the α7nAChR subunit. Exposure of primary human macrophages and murine RAW 264.7 macrophage-like cells to selective ligands for α7nAChR for 1 h in vitro attenuated TNF production for up to 24 h in response to endotoxin. Pharmacological inhibition of adenylyl cyclase (AC) and knockdown of adenylyl cyclase 6 (AC6) or c-FOS abolished cholinergic suppression of endotoxin-induced TNF release. These findings indicate that action potentials in the inflammatory reflex trigger a change in macrophage behavior that requires AC and phosphorylation of the cAMP response element binding protein (CREB). These observations further our mechanistic understanding of neural regulation of inflammation and may have implications for development of bioelectronic medicine treatment of inflammatory diseases.

Preoperative smoking history is associated with decreased risk of early postoperative cognitive dysfunction in patients of advanced age after noncardiac surgery: a prospective observational cohort study

Objective

Prevention of postoperative cognitive dysfunction (POCD) in patients of advanced age remains unclear. Studies have shown that the cholinergic anti-inflammatory pathway contributes to a decreased risk of POCD and that nicotine stimulates the cholinergic anti-inflammatory pathway. We investigated whether patients of advanced age with a preoperative smoking history have a decreased risk of POCD.

Methods

In total, 382 patients (190 smokers, 192 nonsmokers) aged ≥60 years who underwent major noncardiac surgery were enrolled. Cognitive function was assessed, and multivariate logistic regression analyses were performed to identify risk factors.

Results

On postoperative days 5 and 7, 111 (29.05%) and 90 (23.56%) patients exhibited POCD, respectively. A preoperative smoking history was significantly correlated with a decreased risk of POCD. A high serum tumor necrosis factor-α (TNF-α) level on the operative day was significantly associated with an increased risk of POCD. Early POCD was significantly associated with the sufentanil dosage, age, and education level. The hospital stay in patients with and without POCD was 10.54 ± 2.03 and 8.33 ± 1.58 days, respectively.

Conclusion

A preoperative smoking history was associated with a decreased risk of early POCD, and a high serum TNF-α level was significantly associated with an increased risk of POCD.

Health, pre-disease and critical transition to disease in the psycho-immune-neuroendocrine network: Are there distinct states in the progression from health to major depressive disorder?

The psycho-immune-neuroendocrine (PINE) network is a regulatory network of interrelated physiological pathways that have been implicated in major depressive disorder (MDD). A model of disease progression for MDD is presented where the stable, healthy state of the PINE network (PINE physiome) undergoes progressive pathophysiological changes to an unstable but reversible pre-disease state (PINE pre-diseasome) with chronic stress. The PINE network may then undergo critical transition to a stable, possibly irreversible disease state of MDD (PINE pathome). Critical transition to disease is heralded by early warning signs which are detectible by biomarkers specific to the PINE network and may be used as a screening test for MDD. Critical transition to MDD may be different for each individual, as it is reliant on diathesis, which comprises genetic predisposition, intrauterine and developmental factors. Finally, we propose the PINE pre-disease state may form a "universal pre-disease state" for several non-communicable diseases (NCDs), and critical transition of the PINE network may lead to one of several frequently associated disease states (influenced by diathesis), supporting the existence of a common Chronic Illness Risk Network (CIRN). This may provide insight into both the puzzle of multifinality and the growing clinical challenge of multimorbidity.

Pharmacological potentiation of the efferent vagus nerve attenuates blood pressure and renal injury in a murine model of systemic lupus erythematosus

Recent evidence suggests hypertension may be secondary to chronic inflammation that results from hypoactive neuro-immune regulatory mechanisms. To further understand this association, we used systemic lupus erythematosus (SLE) as a model of inflammation-induced hypertension. In addition to prevalent inflammatory kidney disease and hypertension, SLE patients suffer from dysautonomia in the form of decreased efferent vagal tone. Based on this, the cholinergic anti-inflammatory pathway, an endogenous vagus-to-spleen mechanism that, when activated results in decreases in systemic inflammation, may be compromised in SLE. We hypothesized that stimulation of the cholinergic anti-inflammatory pathway via pharmacological potentiation of the efferent vagus nerve would reduce inflammation and halt the development of hypertension and renal injury in SLE. Female NZBWF1 mice, an established model of murine SLE, and female control mice were treated with galantamine (4 mg/kg daily ip), an acetylcholinesterase inhibitor, or saline for 14 days. At the end of therapy, carotid catheters were surgically implanted and were used to measure mean arterial pressure before the animals were euthanized. Chronic galantamine administration attenuated both splenic and renal cortical inflammation, which likely explains why the hypertension and renal injury (i.e., glomerulosclerosis and fibrosis) typically observed in murine SLE was attenuated following therapy. Based on this, the anti-inflammatory, antihypertensive, and renoprotective effects of galantamine may be mediated through activation of the cholinergic anti-inflammatory pathway. It is possible that dysfunction of the cholinergic anti-inflammatory pathway exists in SLE at the level of the efferent vagus nerve and promoting restoration of its activity through central cholinergic receptor activation may be beneficial.

Connection between Systemic Inflammation and Neuroinflammation Underlies Neuroprotective Mechanism of Several Phytochemicals in Neurodegenerative Diseases

Oxidative damage, mitochondrial dysfunction, and neuroinflammation are strongly implicated in the pathogenesis of neurodegenerative diseases including Alzheimer's disease (AD) and Parkinson's disease (PD), and a substantial portion of elderly population at risk of these diseases requires nutritional intervention to benefit health due to lack of clinically relevant drugs. To this end, anti-inflammatory mechanisms of several phytochemicals such as curcumin, resveratrol, propolis, polyunsaturated fatty acids (PUFAs), and ginsenosides have been extensively studied. However, correlation of the phytochemicals with neuroinflammation or brain nutrition is not fully considered, especially in their therapeutic mechanism for neuronal damage or dysfunction. In this article, we review the advance in antioxidative and anti-inflammatory effects of phytochemicals and discuss the potential communication with brain microenvironment by improved gastrointestinal function, enhanced systemic immunity, and neuroprotective outcomes. These data show that phytochemicals may modulate and suppress neuroinflammation of the brain by several approaches: (1) reducing systemic inflammation and infiltration via the blood-brain barrier (BBB), (2) direct permeation into the brain parenchyma leading to neuroprotection, (3) enhancing integrity of disrupted BBB, and (4) vagal reflex-mediated nutrition and protection by gastrointestinal function signaling to the brain. Therefore, many phytochemicals have multiple potential neuroprotective approaches contributing to therapeutic benefit for pathogenesis of neurodegenerative diseases, and development of strategies for preventing these diseases represents a considerable public health concern and socioeconomic burden.

The mouse autonomic nervous system modulates inflammation and epithelial renewal after corneal abrasion through the activation of distinct local macrophages

Inflammation and reepithelialization after corneal abrasion are critical for the rapid restoration of vision and the prevention of microbial infections. However, the endogenous regulatory mechanisms are not completely understood. Here we report that the manipulation of autonomic nervous system (ANS) regulates the inflammation and healing processes. The activation of sympathetic nerves inhibited reepithelialization after corneal abrasion but increased the influx of neutrophils and the release of inflammatory cytokines. Conversely, the activation of parasympathetic nerves promoted reepithelialization and inhibited the influx of neutrophils and the release of inflammatory cytokines. Furthermore, we observed that CD64⁺CCR2⁺ macrophages in the cornea preferentially expressed the β-2 adrenergic receptor (AR), whereas CD64⁺CCR2^- macrophages preferentially expressed the α-7 nicotinic acetylcholine receptor (α7nAChR). After abrasion, the topical administration of a β2AR agonist further enhanced the expression of the proinflammatory genes in the CD64⁺CCR2⁺ cell subset sorted from injured corneas. In contrast, the topical administration of an α7nAChR agonist further enhanced the expression of the anti-inflammatory genes in the CD64⁺CCR2^- subset. Thus crosstalk between the ANS and local macrophage populations is necessary for the progress of corneal wound repair. Manipulation of ANS inputs to the wounded cornea may represent an alternative approach to the treatment of impaired wound healing.

C-Reactive Protein Stimulates Nicotinic Acetylcholine Receptors to Control ATP-Mediated Monocytic Inflammasome Activation

Blood levels of the acute phase reactant C-reactive protein (CRP) are frequently measured as a clinical marker for inflammation, but the biological functions of CRP are still controversial. CRP is a phosphocholine (PC)-binding pentraxin, mainly produced in the liver in response to elevated levels of interleukin-1β (IL-1β) and of the IL-1β-dependent cytokine IL-6. While both cytokines play important roles in host defense, excessive systemic IL-1β levels can cause life-threatening diseases such as trauma-associated systemic inflammation. We hypothesized that CRP acts as a negative feedback regulator of monocytic IL-1β maturation and secretion. Here, we demonstrate that CRP, in association with PC, efficiently reduces ATP-induced inflammasome activation and IL-1β release from human peripheral blood mononuclear leukocytes and monocytic U937 cells. Effective concentrations are in the range of marginally pathologic CRP levels (IC50 = 4.9 µg/ml). CRP elicits metabotropic functions at nicotinic acetylcholine (ACh) receptors (nAChRs) containing subunits α7, α9, and α10 and suppresses the function of ATP-sensitive P2X7 receptors in monocytic cells. Of note, CRP does not induce ion currents at conventional nAChRs, suggesting that CRP is a potent nicotinic agonist controlling innate immunity without entailing the risk of adverse effects in the nervous system. In a prospective study on multiple trauma patients, IL-1β plasma concentrations negatively correlated with preceding CRP levels, whereas inflammasome-independent cytokines IL-6, IL-18, and TNF-α positively correlated. In conclusion, PC-laden CRP is an unconventional nicotinic agonist that potently inhibits ATP-induced inflammasome activation and might protect against trauma-associated sterile inflammation.

Brain Stimulation Differentially Modulates Nociception and Inflammation in Aversive and Non-aversive Behavioral Conditions

Inflammation and pain are major clinical burdens contributing to multiple disorders and limiting the quality of life of patients. We previously reported that brain electrical stimulation can attenuate joint inflammation in experimental arthritis. Here, we report that non-aversive electrical stimulation of the locus coeruleus (LC), the paraventricular hypothalamic nucleus (PVN) or the ventrolateral column of the periaqueductal gray matter (vlPAG) decreases thermal pain sensitivity, knee inflammation and synovial neutrophilic infiltration in rats with intra-articular zymosan. We also analyzed the modulation of pain and inflammation during aversive neuronal stimulation, which produces defensive behavioral responses such as freezing immobility to avoid predator detection. Electrical stimulation with higher intensity to induce freezing immobility in rats further reduces pain but not inflammation. However, tonic immobility further reduces pain, knee inflammation and synovial neutrophilic infiltration in guinea pigs. The duration of the tonic immobility increases the control of pain and inflammation. These results reveal survival behavioral and neuromodulatory mechanisms conserved in different species to control pain and inflammation in aversive life-threatening conditions. Our results also suggest that activation of the LC, PVN, or vlPAG by non-invasive methods, such as physical exercise, meditation, psychological interventions or placebo treatments may reduce pain and joint inflammation in arthritis without inducing motor or behavioral alterations.

Sex differences in how inflammation affects behavior: What we can learn from experimental inflammatory models in humans

Human models demonstrate that experimental activation of the innate immune system has profound effects on brain activation and behavior, inducing fatigue, worsened mood and pain sensitivity. It has been proposed that inflammation is a mechanism involved in the etiology and maintenance of depression, chronic pain and long-term fatigue. These diseases show a strong female overrepresentation, suggesting that a better understanding of sex differences in how inflammation drives behavior could help the development of individualized treatment interventions. For this purpose, we here review sex differences in studies using experimental inflammatory models to investigate changes in brain activity and behavior. We suggest a model in which inflammation accentuates sex differences in brain networks and pre-existing vulnerability factors. This effect could render women more vulnerable to the detrimental effects of immune-to-brain communication over time. We call for systematic and large scale investigations of vulnerability factors for women in the behavioral response to inflammation.

Mechanisms in hypertension and target organ damage: Is the role of the thymus key? (Review)

A variety of cells and cytokines have been shown to be involved in the whole process of hypertension. Data from experimental and clinical studies on hypertension have confirmed the key roles of immune cells and inflammation in the process. Dysfunction of the thymus, which modulates the development and maturation of lymphocytes, has been shown to be associated with the severity of hypertension. Furthermore, gradual atrophy, functional decline or loss of the thymus has been revealed to be associated with aging. The restoration or enhancement of thymus function via upregulation in the expression of thymus transcription factors forkhead box N1 or thymus transplantation may provide an option to halt or reverse the pathological process of hypertension. Therefore, the thymus may be key in hypertension and associated target organ damage, and may provide a novel treatment strategy for the clinical management of patients with hypertension in addition to different commercial drugs. The purpose of this review is to summarize and discuss the advances in our understanding of the impact of thymus function on hypertension from data from animal and human studies, and the potential mechanisms.

Identification of a common immune regulatory pathway induced by small heat shock proteins, amyloid fibrils, and nicotine

Although certain dogma portrays amyloid fibrils as drivers of neurodegenerative disease and neuroinflammation, we have found, paradoxically, that amyloid fibrils and small heat shock proteins (sHsps) are therapeutic in experimental autoimmune encephalomyelitis (EAE). They reduce clinical paralysis and induce immunosuppressive pathways, diminishing inflammation. A key question was the identification of the target for these molecules. When sHsps and amyloid fibrils were chemically cross-linked to immune cells, a limited number of proteins were precipitated, including the α7 nicotinic acetylcholine receptor (α7 NAChR). The α7 NAChR is noteworthy among the over 20 known receptors for amyloid fibrils, because it plays a central role in a well-defined immune-suppressive pathway. Competitive binding between amyloid fibrils and α-bungarotoxin to peritoneal macrophages (MΦs) confirmed the involvement of α7 NAChR. The mechanism of immune suppression was explored, and, similar to nicotine, amyloid fibrils inhibited LPS induction of a common set of inflammatory cytokines while inducing Stat3 signaling and autophagy. Consistent with this, previous studies have established that nicotine, sHsps, and amyloid fibrils all were effective therapeutics in EAE. Interestingly, B lymphocytes were needed for the therapeutic effect. These results suggest that agonists of α7 NAChR might have therapeutic benefit for a variety of inflammatory diseases.

Cortical stimulation in conscious rats controls joint inflammation

The neuronal control of the immune system is fundamental to the development of new therapeutic strategies for inflammatory disorders. Recent studies reported that afferent vagal stimulation attenuates peripheral inflammation by activating specific sympathetic central and peripheral networks, but only few subcortical brain areas were investigated. In the present study, we report that afferent vagal stimulation also activates specific cortical areas, as the parietal and cingulate cortex. Since these cortical structures innervate sympathetic-related areas, we investigate whether electrical stimulation of parietal cortex can attenuate knee joint inflammation in non-anesthetized rats. Our results show that cortical stimulation in rats increased sympathetic activity and improved joint inflammatory parameters, such as local neutrophil infiltration and pro-inflammatory cytokine levels, without causing behavioral disturbance, brain epileptiform activity or neural damage. In addition, we superposed the areas activated by afferent vagal or cortical stimulation to map common central structures to depict a brain immunological homunculus that can allow novel therapeutic approaches against inflammatory joint diseases, such as rheumatoid arthritis.

Nasal priming by a murine coronavirus provides protective immunity against lethal heterologous virus pneumonia

The nasal mucosa is an important component of mucosal immunity. Immunogenic particles in inspired air are known to activate the local nasal mucosal immune system and can lead to sinonasal inflammation; however, little is known about the effect of this activation on the lung immune environment. Here, we showed that nasal inoculation of murine coronavirus (CoV) in the absence of direct lung infection primes the lung immune environment by recruiting activated monocytes (Ly6C+ inflammatory monocytes) and NK cells into the lungs. Unlike infiltration of these cells into directly infected lungs, a process that requires type I IFN signaling, nasally induced infiltration of Ly6C+ inflammatory monocytes into the lungs is IFN-I independent. These activated macrophages ingested antigen and migrated to pulmonary lymph nodes, and enhanced both innate and adaptive immunity after heterologous virus infection. Clinically, such nasal-only inoculation of MHV-1 failed to cause pneumonia but significantly reduced mortality and morbidity of lethal pneumonia caused by severe acute respiratory syndrome CoV (SARS-CoV) or influenza A virus. Together, the data indicate that the nose and upper airway remotely prime the lung immunity to protect the lungs from direct viral infections.

Circadian rhythm and sleep-wake systems share the dynamic extracellular synaptic milieu

The mammalian circadian and sleep-wake systems are closely aligned through their coordinated regulation of daily activity patterns. Although they differ in their anatomical organization and physiological processes, they utilize overlapping regulatory mechanisms that include an assortment of proteins and molecules interacting within the extracellular space. These extracellular factors include proteases that interact with soluble proteins, membrane-attached receptors and the extracellular matrix; and cell adhesion molecules that can form complex scaffolds connecting adjacent neurons, astrocytes and their respective intracellular cytoskeletal elements. Astrocytes also participate in the dynamic regulation of both systems through modulating neuronal appositions, the extracellular space and/or through release of gliotransmitters that can further contribute to the extracellular signaling processes. Together, these extracellular elements create a system that integrates rapid neurotransmitter signaling across longer time scales and thereby adjust neuronal signaling to reflect the daily fluctuations fundamental to both systems. Here we review what is known about these extracellular processes, focusing specifically on areas of overlap between the two systems. We also highlight questions that still need to be addressed. Although we know many of the extracellular players, far more research is needed to understand the mechanisms through which they modulate the circadian and sleep-wake systems.

Identification of cytokine-specific sensory neural signals by decoding murine vagus nerve activity

The nervous system maintains physiological homeostasis through reflex pathways that modulate organ function. This process begins when changes in the internal milieu (e.g., blood pressure, temperature, or pH) activate visceral sensory neurons that transmit action potentials along the vagus nerve to the brainstem. IL-1β and TNF, inflammatory cytokines produced by immune cells during infection and injury, and other inflammatory mediators have been implicated in activating sensory action potentials in the vagus nerve. However, it remains unclear whether neural responses encode cytokine-specific information. Here we develop methods to isolate and decode specific neural signals to discriminate between two different cytokines. Nerve impulses recorded from the vagus nerve of mice exposed to IL-1β and TNF were sorted into groups based on their shape and amplitude, and their respective firing rates were computed. This revealed sensory neural groups responding specifically to TNF and IL-1β in a dose-dependent manner. These cytokine-mediated responses were subsequently decoded using a Naive Bayes algorithm that discriminated between no exposure and exposures to IL-1β and TNF (mean successful identification rate 82.9 ± 17.8%, chance level 33%). Recordings obtained in IL-1 receptor-KO mice were devoid of IL-1β-related signals but retained their responses to TNF. Genetic ablation of TRPV1 neurons attenuated the vagus neural signals mediated by IL-1β, and distal lidocaine nerve block attenuated all vagus neural signals recorded. The results obtained in this study using the methodological framework suggest that cytokine-specific information is present in sensory neural signals within the vagus nerve.

Impaired CD8 T cell antiviral immunity following acute spinal cord injury

BACKGROUND

Spinal cord injury (SCI) disrupts essential neuroimmune communication, leading to severe immune depression. Previous studies confirmed immune dysfunction in mice with chronic SCI and following high thoracic level injury where sympathetic innervation of the spleen is disrupted. Here, we induced a mid-thoracic injury where integrity of the sympathetic response is maintained and investigated the antiviral T cell response to influenza virus after acute SCI.

METHODS

One week following a contusion SCI at thoracic level T9, mice were infected intranasally with influenza virus. Profiles of immune cell populations were analyzed before infection, and virus-specific CD8 T cell response was analyzed 7 days post-infection.

RESULTS

Following intranasal infection, injured mice had prolonged recovery and significant weight loss. Importantly, expansion and effector functions of virus-specific CD8 T cells were decreased in injured mice. The compromised CD8 T cell response was associated with inflammation and stress responses initiated after injury. Regulatory mechanisms, including increased regulatory T cells (Tregs) and upregulated PD-1/PD-L1, were induced following SCI. Furthermore, we show that increased corticosterone (CORT) levels can inhibit CD8 T cells and that blocking CORT in vivo following SCI enhances CD8 T cell antiviral responses.

CONCLUSIONS

Our results show that mice with mid-thoracic SCI have impaired CD8 T cell function during the acute stage of injury, indicating that impaired antiviral responses occur rapidly following SCI and is not dependent on injury level.

Divergent humoral responses to 23-valent pneumococcal polysaccharide vaccine in critically-ill burn and neurosurgical patients

INTRODUCTION

Critically ill hospitalized patients are at increased risk of infection so we assessed the immunogenicity of 23-valent pneumococcal polysaccharide vaccine (PPSV23) administered within six days of injury.

METHODS

This prospective observational study compared the immunogenicity of PPSV23 among critically ill burn and neurosurgical patients at a tertiary, academic medical center. Patients received PPSV23 vaccination within six days of ICU admission per standard of care. Consent was obtained to measure concentrations of vaccine-specific IgG to 14 of 23 serotype capsule-specific IgG in serum prior to and 14-35 days following PPSV23. A successful immunologic response was defined as both a ≥2-fold rise in capsule-specific IgG from baseline and concentrations of >1 mcg/mL to 10 of 14 measured vaccine serotypes. Immunologic response was compared between burn and neurosurgical patients. Multiple variable regression methods were used to explore associations of clinical and laboratory parameters to immunologic responses.

RESULTS

Among the 16 burn and 27 neurosurgical patients enrolled, 87.5% and 40.7% generated a successful response to the vaccine, respectively (p = 0.004). Both median post-PPSV23 IgG concentrations (7.79 [4.56-18.1] versus 2.93 [1.49-8.01] mcg/mL; p = 0.006) and fold rises (10.66 [7.44-14.56] versus 3.48 [1.13-6.59]; p<0.001) were significantly greater in burn compared with neurosurgical patients. Presence of burn injury was directly and days from injury to immunization were inversely correlated with successful immunologic response (both p<0.03). Burn injury was associated with both increased median antibody levels post-PPSV23 and fold rise to 14 vaccine serotypes (p<0.03), whereas absolute lymphocyte count was inversely correlated with median antibody concentrations (p = 0.034).

CONCLUSION

Critically ill burn patients can generate successful responses to PPSV23 during acute injury whereas responses among neurosurgical patients is comparatively blunted. Further study is needed to elucidate the mechanisms of differential antigen responsiveness in these populations, including the role of acute stress responses, as well as the durability of these antibody responses.

Objecthood, Agency and Mutualism in Valenced Farm Animal Environments

Genetic selection of farm animals for productivity, and intensification of farming practices have yielded substantial improvements in efficiency; however, the capacity of animals to cope with environmental challenges has diminished. Understanding how the animal and environment interact is central to efforts to improve the health, fitness, and welfare of animals through breeding and management strategies. The review examines aspects of the environment that are sensed by the animal. The predictive brain model of sensory perception and motor action (the Bayesian brain model) and its recent extension to account for anticipatory, predictive control of physiological activities is described. Afferent sensory input from the immune system, and induction of predictive immune functions by the efferent nervous system are also in accord with the Bayesian brain model. In this model, expected sensory input (from external, physiological and immunological environments) is reconciled with actual sensory input through behavioural, physiological and immune actions, and through updating future expectations. Sustained discrepancy between expected and actual sensory inputs occurs when environmental encounters cannot be predicted and controlled resulting in stress and negative affective states. Through these processes, from the animal's perspective, aspects of the environment acquire a negative or positive character: that is the environment becomes valenced. In a homeostatic manner, affective experience guides the animal towards synchronisation and a greater degree of mutualism with its environment. A better understanding of the dynamic among environmental valence, animal affect and mutualism may provide a better understanding of genetic and phenotypic links between temperament, immune function, metabolic performance, affective state, and resilience in farm animals, and provide further opportunities to improve their welfare.

Heart Rate Variability Markers as Correlates of Survival in Recipients of Hematopoietic Cell Transplantation

OBJECTIVES

To assess pre-/post-transplantation changes in autonomic tone, as measured by heart rate variability (HRV), among patients undergoing hematopoietic cell transplantation (HCT) and to look at those changes as they relate to post-transplantation survival rates. 
.

SAMPLE & SETTING

Data were derived from a sample of 27 English-speaking patients undergoing allogeneic or autologous HCT at Stanford University. 
.

METHODS & VARIABLES

A survival analysis using the Kaplan-Meier estimator was employed to explore whether increased HRV would enhance survival probabilities over time among patients undergoing HCT.
.

RESULTS

An increased probability of survival was significantly related to increases in two HRV indexes.

IMPLICATIONS FOR NURSING

HRV may be a useful predictor of mortality among patients undergoing HCT. Interventions deliverable by nurses could be used to enhance HRV for patients identified as being at risk for early mortality.

Curcumin attenuates collagen-induced inflammatory response through the "gut-brain axis"

BACKGROUND

Previous studies have demonstrated that oral administration of curcumin exhibited an anti-arthritic effect despite its poor bioavailability. The present study aimed to explore whether the gut-brain axis is involved in the therapeutic effect of curcumin.

METHODS

The collagen-induced arthritis (CIA) rat model was induced by immunization with an emulsion of collagen II and complete Freund's adjuvant. Sympathetic and parasympathetic tones were measured by electrocardiographic recordings. Unilateral cervical vagotomy (VGX) was performed before the induction of CIA. The ChAT, AChE activities, and serum cytokine levels were determined by ELISA. The expression of the high-affinity choline transporter 1 (CHT1), ChAT, and vesicular acetylcholine transporter (VAChT) were determined by real-time PCR and immunohistochemical staining. The neuronal excitability of the vagus nerve was determined by whole-cell patch clamp recording.

RESULTS

Oral administration of curcumin restored the imbalance between the sympathetic and parasympathetic tones in CIA rats and increased ChAT activity and expression of ChAT and VAChT in the gut, brain, and synovium. Additionally, VGX eliminated the effects of curcumin on arthritis and ACh biosynthesis and transport. Electrophysiological data showed that curcumin markedly increased neuronal excitability of the vagus nerve. Furthermore, selective α7 nAChR antagonists abolished the effects of curcumin on CIA.

CONCLUSIONS

Our results demonstrate that curcumin attenuates CIA through the "gut-brain axis" by modulating the function of the cholinergic system. These findings provide a novel approach for mechanistic studies of anti-arthritic compounds with low oral absorption and bioavailability.

Neuroimmune Interactions: From the Brain to the Immune System and Vice Versa

Because of the compartmentalization of disciplines that shaped the academic landscape of biology and biomedical sciences in the past, physiological systems have long been studied in isolation from each other. This has particularly been the case for the immune system. As a consequence of its ties with pathology and microbiology, immunology as a discipline has largely grown independently of physiology. Accordingly, it has taken a long time for immunologists to accept the concept that the immune system is not self-regulated but functions in close association with the nervous system. These associations are present at different levels of organization. At the local level, there is clear evidence for the production and use of immune factors by the central nervous system and for the production and use of neuroendocrine mediators by the immune system. Short-range interactions between immune cells and peripheral nerve endings innervating immune organs allow the immune system to recruit local neuronal elements for fine tuning of the immune response. Reciprocally, immune cells and mediators play a regulatory role in the nervous system and participate in the elimination and plasticity of synapses during development as well as in synaptic plasticity at adulthood. At the whole organism level, long-range interactions between immune cells and the central nervous system allow the immune system to engage the rest of the body in the fight against infection from pathogenic microorganisms and permit the nervous system to regulate immune functioning. Alterations in communication pathways between the immune system and the nervous system can account for many pathological conditions that were initially attributed to strict organ dysfunction. This applies in particular to psychiatric disorders and several immune-mediated diseases. This review will show how our understanding of this balance between long-range and short-range interactions between the immune system and the central nervous system has evolved over time, since the first demonstrations of immune influences on brain functions. The necessary complementarity of these two modes of communication will then be discussed. Finally, a few examples will illustrate how dysfunction in these communication pathways results in what was formerly considered in psychiatry and immunology to be strict organ pathologies.

Neuropathy correlated with imbalanced Foxp3/IL-17 in bone marrow microenvironment of patients with acute myeloid leukemia

Bone marrow (BM) neural tissues are important components of bone marrow microenvironment and play important roles in normal hematopoiesis. Neuropathy of BM can cause immunological alteration in hematopoietic microenvironment. It also can induce the impairment of normal hematopoiesis and promote the development of hematologic diseases. In the present study, we determined the expression levels and clinical significances of nerve-related molecules [nestin, tyrosine hydroxylase (TH), Glial Fibrillary Acidic protein (GFAP) and S100B] and T helper-related molecules (IL-17, Foxp3) in BM of AML patients and controls by immunohistochemical analysis and RT-PCR. Our results showed that the positive rates and expression levels of nestin, TH, GFAP and IL-17 were significantly decreased while Foxp3 and the ratio of Foxp3/IL-17 were statistically elevated in BM of AML patients. We found that there were significantly positive correlations between nestin with TH and IL-17 in BM of AML patients. We also observed significantly negative correlations between nestin with TH and Foxp3/IL-17 ratio. Moreover, the expression of nestin was positively correlated with the overall survival of AML patients. Our study suggests that neuropathy together with imbalanced T helper immunology in bone marrow might play important roles in AML.

A novel flexible cuff-like microelectrode for dual purpose, acute and chronic electrical interfacing with the mouse cervical vagus nerve

OBJECTIVE

Neural reflexes regulate immune responses and homeostasis. Advances in bioelectronic medicine indicate that electrical stimulation of the vagus nerve can be used to treat inflammatory disease, yet the understanding of neural signals that regulate inflammation is incomplete. Current interfaces with the vagus nerve do not permit effective chronic stimulation or recording in mouse models, which is vital to studying the molecular and neurophysiological mechanisms that control inflammation homeostasis in health and disease. We developed an implantable, dual purpose, multi-channel, flexible 'microelectrode' array, for recording and stimulation of the mouse vagus nerve.

APPROACH

The array was microfabricated on an 8 µm layer of highly biocompatible parylene configured with 16 sites. The microelectrode was evaluated by studying the recording and stimulation performance. Mice were chronically implanted with devices for up to 12 weeks.

MAIN RESULTS

Using the microelectrode in vivo, high fidelity signals were recorded during physiological challenges (e.g potassium chloride and interleukin-1β), and electrical stimulation of the vagus nerve produced the expected significant reduction of blood levels of tumor necrosis factor (TNF) in endotoxemia. Inflammatory cell infiltration at the microelectrode 12 weeks of implantation was limited according to radial distribution analysis of inflammatory cells.

SIGNIFICANCE

This novel device provides an important step towards a viable chronic interface for cervical vagus nerve stimulation and recording in mice.

α7 Nicotinic Agonist AR-R17779 Protects Mice against 2,4,6-Trinitrobenzene Sulfonic Acid-Induced Colitis in a Spleen-Dependent Way

The existence of a cholinergic anti-inflammatory pathway negatively modulating the inflammatory and immune responses in various clinical conditions and experimental models has long been postulated. In particular, the protective involvement of the vagus nerve and of nicotinic Ach receptors (nAChRs) has been proposed in intestinal inflammation and repeatedly investigated in DSS- and TNBS-induced colitis. However, the role of α7 nAChRs stimulation is still controversial and the potential contribution of α4β2 nAChRs has never been explored in this experimental condition. Our aims were therefore to pharmacologically investigate the role played by both α7 and α4β2 nAChRs in the modulation of the local and systemic inflammatory responses activated in TNBS-induced colitis in mice and to assess the involvement of the spleen in nicotinic responses. To this end, TNBS-exposed mice were sub-acutely treated with various subcutaneous doses of highly selective agonists (AR-R17779 and TC-2403) and antagonists (methyllycaconitine and dihydro-β-erythroidine) of α7 and α4β2 nAChRs, respectively, or with sulfasalazine 50 mg/kg per os and clinical and inflammatory responses were evaluated by means of biochemical, histological and flow cytometry assays. α4β2 ligands evoked weak and contradictory effects, while α7 nAChR agonist AR-R17779 emerged as the most beneficial treatment, able to attenuate several local markers of colitis severity and to revert the rise in splenic T-cells and in colonic inflammatory cytokines levels induced by haptenization. After splenectomy, AR-R17779 lost its protective effects, demonstrating for the first time that, in TNBS-model of experimental colitis, the anti-inflammatory effect of exogenous α7 nAChR stimulation is strictly spleen-dependent. Our findings showed that the selective α7 nAChRs agonist AR-R17779 exerted beneficial effects in a model of intestinal inflammation characterized by activation of the adaptive immune system and that the spleen is essential to mediate this cholinergic protection.

Neutrophil polarization by IL-27 as a therapeutic target for intracerebral hemorrhage

Shortly after intracerebral hemorrhage, neutrophils infiltrate the intracerebral hemorrhage-injured brain. Once within the brain, neutrophils degranulate, releasing destructive molecules that may exacerbate brain damage. However, neutrophils also release beneficial molecules, including iron-scavenging lactoferrin that may limit hematoma/iron-mediated brain injury after intracerebral hemorrhage. Here, we show that the immunoregulatory cytokine interleukin-27 is upregulated centrally and peripherally after intracerebral hemorrhage. Data from rodent models indicate that interleukin-27 modifies neutrophil maturation in the bone marrow, suppressing their production of pro-inflammatory/cytotoxic products while increasing their production of beneficial iron-scavenging molecules, including lactoferrin. Finally, interleukin-27 or lactoferrin administration results in reduced edema, enhanced hematoma clearance, and improved neurological outcomes in an animal model of intracerebral hemorrhage. These results suggest that interleukin-27/lactoferrin-mediated modulations of neutrophil function may represent a therapeutically viable concept for the modification of neutrophils toward a “beneficial” phenotype for the treatment of intracerebral hemorrhage.

Neutrophils are important modulators of tissue damage after intracerebral hemorrhage (ICH), but how this function is regulated is not clear. Here, the authors show interleukin-27 promotes the tissue-protecting functions of neutrophils via, at least partly, the induction of lactoferrin to present a potential therapy for ICH.

Construction of a lentiviral vector containing shRNA targeting ADAM17 and its role in attenuating endotoxemia in mice

Systemic inflammatory response syndrome is a pathophysiological inflammatory response mediated largely by tumor necrosis factor-α (TNF-α), in response to infectious or non-infectious stimuli. TNF-α secretion in response to bacterial lipopolysaccharide (LPS) is regulated in part by disintegrin and metalloproteinase domain-containing protein 17 (ADAM17). Therefore, the present study aimed to identify an effective inhibitor of ADAM17, in order to control inflammation and associated processes. In the present study, a lentiviral vector expressing short hairpin (sh)RNA targeting the ADAM17 gene was constructed. U937 cells were infected with the lentivirus and stimulated with LPS. ADAM17 expression was assessed by western blotting and TNF-α secretion was assessed by ELISA analysis. The lentivirus was additionally tested in vivo in a mouse model of endotoxemia and sTNF-α expression was assessed by flow cytometry in peritoneal macrophages. In vitro, the ADAM17 shRNA lentivirus reduced ADAM17 expression, and prevented TNF-α maturation in U937 cells. In vivo, mice exposed to the ADAM17 shRNA lentivirus prior to LPS-induced endotoxemia exhibited fewer signs of inflammation and less tissue damage compared with the control mice. In conclusion, the present study successfully constructed a shRNA lentiviral vector targeting the ADAM17 gene that exhibited apparent in vitro and in vivo effects on TNF-α processing in response to an LPS challenge. The results of the present study may aid the design and improvement of drugs designed to inhibit the function of ADAM17, and suggested a novel means of controlling inflammation and associated processes.

Potential Roles of Peripheral Dopamine in Tumor Immunity

Recent years, immunotherapy has turned out to be a promising strategy against tumors. Peripheral dopamine (DA) has important roles in immune system among tumor patients. Accumulated reports demonstrate variable expression and distribution of DA receptors (DRs) in diverse immune cells. Interestingly, peripheral DA also involves in tumor progression and it exerts anticancer effects on immunomodulation, which includes inflammasomes in cancer, function of immune effector cells, such as T lymphocytes, myeloid-derived suppressor cells (MDSCs), tumor-associated macrophages (TAMs) and natural killer (NK) cells. Given the specific immunologic status, DA medication may be a valuable candidate in pancreatic cancer treatment. The major purpose of this review is to discuss the novel potential interactions between peripheral dopamine and tumor immunity.

Clinical approach to autonomic dysfunction

Patients with autonomic dysfunction may present with a variety of seemingly unrelated symptoms, both generalised and involving specific systems, including fatigue, difficulty concentrating, orthostatic intolerance, palpitations, constipation or diarrhoea, early satiety, urinary retention or incontinence and erectile dysfunction. Failure to connect the diverse symptoms with a single underlying mechanism may lead to incorrect diagnoses, inappropriate interventions and frustration on the part of both doctors and patients. We describe recent developments in the understanding of the pathophysiology of autonomic dysfunction, including the link between the autonomic and immune systems resulting in the 'inflammatory reflex'. We then provide a rationale to guide the management of patients exhibiting features of autonomic dysfunction, including postural tachycardia syndrome.

Vasovagal tonus index (VVTI) as an indirect assessment of remission status in canine multicentric lymphoma undergoing multi-drug chemotherapy

Vasovagal tonus index (VVTI) is an indirect measure of heart rate variability and may serve as a marker of disease severity. Higher heart rate variability has predicted lower tumour burden and improved survival in humans with various tumour types. The purpose of this pilot study was to evaluate VVTI as a biomarker of remission status in canine lymphoma. The primary hypothesis was that VVTI would be increased in dogs in remission compared to dogs out of remission. Twenty-seven dogs were prospectively enrolled if they had a diagnosis of intermediate to high-grade lymphoma and underwent multidrug chemotherapy. Serial electrocardiogram data were collected under standard conditions and relationships between VVTI, remission status and other clinical variables were evaluated. VVTI from dogs in remission (partial or complete) did not differ from dogs with fulminant lymphoma (naive or at time of relapse). Dogs in partial remission had higher VVTI than dogs in complete remission (p = 0.021). Higher baseline VVTI was associated with higher subsequent scores (p < 0.001). VVTI also correlated with anxiety level (p = 0.03). Based on this pilot study, VVTI did not hold any obvious promise as a useful clinical biomarker of remission status. Further investigation may better elucidate the clinical and prognostic utility of VVTI in dogs with lymphoma.

Modulation of experimental arthritis by vagal sensory and central brain stimulation

Articular inflammation is a major clinical burden in multiple inflammatory diseases, especially in rheumatoid arthritis. Biological anti-rheumatic drug therapies are expensive and increase the risk of systemic immunosuppression, infections, and malignancies. Here, we report that vagus nerve stimulation controls arthritic joint inflammation by inducing local regulation of innate immune response. Most of the previous studies of neuromodulation focused on vagal regulation of inflammation via the efferent peripheral pathway toward the viscera. Here, we report that vagal stimulation modulates arthritic joint inflammation through a novel "afferent" pathway mediated by the locus coeruleus (LC) of the central nervous system. Afferent vagal stimulation activates two sympatho-excitatory brain areas: the paraventricular hypothalamic nucleus (PVN) and the LC. The integrity of the LC, but not that of the PVN, is critical for vagal control of arthritic joint inflammation. Afferent vagal stimulation suppresses articular inflammation in the ipsilateral, but not in the contralateral knee to the hemispheric LC lesion. Central stimulation is followed by subsequent activation of joint sympathetic nerve terminals inducing articular norepinephrine release. Selective adrenergic beta-blockers prevent the effects of articular norepinephrine and thereby abrogate vagal control of arthritic joint inflammation. These results reveals a novel neuro-immune brain map with afferent vagal signals controlling side-specific articular inflammation through specific inflammatory-processing brain centers and joint sympathetic innervations.