Reflex control of immunity.

Inflammation can cause damage and even death. What controls this primitive and potentially lethal innate immune response to injury and infection? Molecular and neurophysiological studies during the past decade have revealed a pivotal answer: immunity is coordinated by neural circuits that operate reflexively. The afferent arc of the reflex consists of nerves that sense injury and infection.

Role of toll-like receptors 2 and 4, and the receptor for advanced glycation end products in high-mobility group box 1-induced inflammation in vivo.

High-mobility group box 1 (HMGB-1) has been reported as a "late" proinflammatory mediator in sepsis. In vitro data have shown that HMGB-1 can induce activation of intracellular signaling pathways via interaction with at least three pattern recognition receptors: Toll-like receptor (TLR) 2, TLR-4, and the receptor for advanced glycation end products (RAGE). The objective of this study was to investigate the role of these receptors in the in vivo response to HMGB-1.

Experimental therapeutic strategies for severe sepsis: mediators and mechanisms.

Severe sepsis is the leading cause of mortality in intensive care units. The limited ability of current therapies to reduce sepsis mortality rates has fueled research efforts for the development of novel treatment strategies. Through the close collaboration between clinicians and scientists, progress can be seen in the struggle to develop effective therapeutic approaches for the treatment of sepsis and other immune and inflammatory disorders.

The HMGB1 receptor RAGE mediates ischemic brain damage.

In ischemic stroke, the necrotic core is surrounded by a zone of inflammation, in which delayed cell death aggravates the initial insult. Here, we provide evidence that the receptor for advanced glycation end products (RAGE) functions as a sensor of necrotic cell death and contributes to inflammation and ischemic brain damage. The RAGE ligand high mobility group box 1 (HMGB1) was elevated in serum of stroke patients and was released from ischemic brain tissue in a mouse model of cerebral ischemia.

Acetylcholine regulation of synoviocyte cytokine expression by the alpha7 nicotinic receptor.

Objective: The central nervous system can regulate peripheral inflammation, but the efferent neuronal routes and the mediators remain poorly defined. One candidate is the cholinergic pathway, which releases acetylcholine (ACh). This neurotransmitter can bind to the alpha7 cholinergic receptor (alpha7R) expressed by nonneuronal cells and reduce inflammation.

Splenectomy protects against sepsis lethality and reduces serum HMGB1 levels.

High mobility group box 1 (HMGB1) is a critical mediator of lethal sepsis. Previously, we showed that apoptotic cells can activate macrophages to release HMGB1. During sepsis, apoptosis occurs primarily in lymphoid organs, including the spleen and thymus.

Splenic nerve is required for cholinergic antiinflammatory pathway control of TNF in endotoxemia.

The autonomic nervous system maintains homeostasis through its sympathetic and parasympathetic divisions. During infection, cells of the immune system release cytokines and other mediators that cause fever, hypotension, and tissue injury. Although the effect of cytokines on the nervous system has been known for decades, only recently has it become evident that the autonomic nervous system, in turn, regulates cytokine production through neural pathways.

Brain acetylcholinesterase activity controls systemic cytokine levels through the cholinergic anti-inflammatory pathway.

The excessive release of cytokines by the immune system contributes importantly to the pathogenesis of inflammatory diseases. Recent advances in understanding the biology of cytokine toxicity led to the discovery of the "cholinergic anti-inflammatory pathway," defined as neural signals transmitted via the vagus nerve that inhibit cytokine release through a mechanism that requires the alpha7 subunit-containing nicotinic acetylcholine receptor (alpha7nAChR). Vagus nerve regulation of peripheral functions is controlled by brain nuclei and neural networks, but despite considerable importance, little is known about the molecular basis for central regulation of the vagus nerve-based cholinergic anti-inflammatory pathway.

Modulation of TNF release by choline requires alpha7 subunit nicotinic acetylcholine receptor-mediated signaling.

The alpha7 subunit-containing nicotinic acetylcholine receptor (alpha7nAChR) is an essential component in the vagus nerve-based cholinergic anti-inflammatory pathway that regulates the levels of TNF, high mobility group box 1 (HMGB1), and other cytokines during inflammation. Choline is an essential nutrient, a cell membrane constituent, a precursor in the biosynthesis of acetylcholine, and a selective natural alpha7nAChR agonist. Here, we studied the anti-inflammatory potential of choline in murine endotoxemia and sepsis, and the role of the alpha7nAChR in mediating the suppressive effect of choline on TNF release.

Cholinergic agonists attenuate renal ischemia-reperfusion injury in rats.

Inflammation plays a significant role in the pathophysiology of renal ischemia-reperfusion injury. Local inflammation is modulated by the brain via the vagus nerve and nicotinic acetylcholine receptors such that electrical or pharmacologic stimulation of this cholinergic anti-inflammatory pathway results in suppression of proinflammatory cytokine production. We examined the effects of cholinergic stimulation using agonists, nicotine or GTS-21, given before or after bilateral renal ischemia-reperfusion injury in rats.

High Mobility Group Box Protein-1 correlates with renal function in chronic kidney disease (CKD).

Chronic kidney disease (CKD) is associated with inflammation and malnutrition and carries a markedly increased risk of cardiovascular disease (CVD). High Mobility Group Box Protein-1 (HMGB-1) is a 30-kDa nuclear and cytosolic protein known as a transcription and growth factor, recently identified as a proinflammatory mediator of tissue injury. Recent data implicates HMGB-1 in endotoxin lethality, rheumatoid arthritis, and atherosclerosis.

From CNI-1493 to the immunological homunculus: physiology of the inflammatory reflex.

The inflammatory reflex is a neurophysiological mechanism that regulates the immune system. The efferent branch of the reflex the cholinergic anti-inflammatory pathway, which inhibits inflammation by suppressing cytokine synthesis via release of acetylcholine in organs of the reticuloendothelial system, including the spleen, liver, and gastrointestinal tract. Acetylcholine binds to alpha7 nicotinic acetylcholine receptors expressed by macrophages and other cytokine-producing cells.

IL-1alpha and IL-1beta are endogenous mediators linking cell injury to the adaptive alloimmune response.

Preoperative or perioperative ischemic injury of allografts predisposes to graft arteriosclerosis, the major cause of late graft failure. We hypothesize that injured tissues release mediators that increase the production of pathogenic cytokines by alloreactive T cells. We find that freeze-thaw lysates of human endothelial cells (EC) increase both IFN-gamma and IL-17 production by human CD4(+) T cells activated by HLA-DR(+) allogeneic EC.

Transcutaneous vagus nerve stimulation reduces serum high mobility group box 1 levels and improves survival in murine sepsis.

Objective: Electrical vagus nerve stimulation inhibits proinflammatory cytokine production and prevents shock during lethal systemic inflammation through an alpha7 nicotinic acetylcholine receptor (alpha7nAChR)-dependent pathway to the spleen, termed the cholinergic anti-inflammatory pathway. Pharmacologic alpha7nAChR agonists inhibit production of the critical proinflammatory mediator high mobility group box 1 (HMGB1) and rescue mice from lethal polymicrobial sepsis. Here we developed a method of transcutaneous mechanical vagus nerve stimulation and then investigated whether this therapy can protect mice against sepsis lethality.

HMGB1 is a bone-active cytokine.

High mobility group box 1 (HMGB1) is a chromatin protein that acts as an immunomodulatory cytokine upon active release from myeloid cells. HMGB1 is also an alarmin, an endogenous molecule released by dying cells that acts to initiate tissue repair. We have previously reported that osteoclasts and osteoblasts release HMGB1 and release by the latter is regulated by parathyroid hormone (PTH), an agent of bone remodeling.

Systemic inflammation and remote organ injury following trauma require HMGB1.

High-mobility group box 1 (HMGB1) is a 30-kDa DNA-binding protein that displays proinflammatory cytokine-like properties. HMGB1-dependent inflammatory processes have been demonstrated in models of sterile injury, including ischemia-reperfusion injury and hemorrhagic shock. Here, we tested the hypothesis that the systemic inflammatory response and associated remote organ injury that occur after peripheral tissue injury are highly dependent on HMGB1.

Aerobic exercise attenuates inducible TNF production in humans.

Aerobic exercise reduces coronary heart disease risk, but the mechanisms of this protection are not fully understood. Atherosclerosis is an inflammatory disease mediated by monocyte-derived macrophages, which accumulate in arterial plaques and become activated to release factors, including cytokines, that cause damage. Here we studied the effects of aerobic training on monocyte production of tumor necrosis factor (TNF) in whole blood ex vivo.

Cholinergic anti-inflammatory pathway activity and High Mobility Group Box-1 (HMGB1) serum levels in patients with rheumatoid arthritis.

High Mobility Group Box-1 (HMGB1) is a cytokine implicated in the pathogenesis of rheumatoid arthritis (RA) and other inflammatory diseases. The cholinergic anti-inflammatory pathway, a vagus nerve-dependent mechanism, inhibits HMGB1 release in experimental disease models. Here, we examine the relationship between vagus nerve activity and HMGB1 in patients with RA.

RR interval variability is inversely related to inflammatory markers: the CARDIA study.

Recent evidence reveals that the immune system is under the direct control of the vagus nerve via the "cholinergic anti-inflammatory pathway." Stimulation of vagus nerve activity significantly inhibits cytokine levels in animal models, and cholinergic agents inhibit cytokine release by human macrophages. Moreover, when vagus nerve activity is decreased or absent, cytokines are overproduced.

Hemorrhagic shock induces NAD(P)H oxidase activation in neutrophils: role of HMGB1-TLR4 signaling.

Hemorrhagic shock/resuscitation (HS/R)-induced generation of reactive oxygen species (ROS) plays an important role in posthemorrhage inflammation and tissue injury. We have recently reported that HS/R-activated neutrophils (PMN), through release of ROS, serve an important signaling function in mediating alveolar macrophage priming and lung inflammation. PMN NAD(P)H oxidase has been thought to be an important source of ROS following HS/R.

HMGB1 as a potential therapeutic target.

Despite recent advances in antibiotic therapy and intensive care, sepsis remains the most common cause of death in the intensive care units, claiming approximately 225000 victims annually in the USA alone. The pathogenesis of sepsis is attributable, at least in part, to dysregulated systemic inflammatory responses characterized by excessive accumulation of various proinflammatory cytokines. A ubiquitous nuclear protein, high mobility group box 1 (HMGB1), is released by activated macrophages/monocytes, and functions as a late mediator of lethal endotoxaemia and sepsis.

A cardiovascular drug rescues mice from lethal sepsis by selectively attenuating a late-acting proinflammatory mediator, high mobility group box 1.

The pathogenesis of sepsis is mediated in part by bacterial endotoxin, which stimulates macrophages/monocytes to sequentially release early (e.g., TNF, IL-1, and IFN-gamma) and late (e.

Circulating high-mobility group box 1 (HMGB1) concentrations are elevated in both uncomplicated pneumonia and pneumonia with severe sepsis.

Objective: High-mobility group box 1 (HMGB1) has been proposed as a late mediator of sepsis, but human data are sparse and conflicting. We describe plasma HMGB1 concentrations in humans with community-acquired pneumonia (CAP), the most common cause of severe sepsis, and test the hypotheses that HMGB1 levels are higher in CAP than healthy controls, higher in CAP with severe sepsis than CAP without severe sepsis, and higher in severe sepsis nonsurvivors than survivors.

Design: Random, outcome-stratified sample from a prospective study of 1,895 subjects hospitalized with CAP.

Selective alpha7-nicotinic acetylcholine receptor agonist GTS-21 improves survival in murine endotoxemia and severe sepsis.

Objective: Tumor necrosis factor and high mobility group box 1 are critical cytokine mediators of inflammation. The efferent vagus nerve inhibits cytokine release through alpha7-nicotinic acetylcholine receptor-mediated cholinergic signaling. Here we studied whether GTS-21, a selective alpha7-nicotinic acetylcholine receptor agonist, inhibits proinflammatory cytokines in vitro and in vivo and improves survival in murine endotoxemia and severe sepsis.