The cholinergic anti-inflammatory pathway regulates the
innate immune response
The innate, or nonspecific, immune system is one of the two main immunity strategies (the other being the adaptive immune system) in vertebrates. The innate immune system is an older evolutionary defense strategy, relatively speaking, and is th ...
to injury,
pathogen
In biology, a pathogen ( el, πάθος, "suffering", "passion" and , "producer of") in the oldest and broadest sense, is any organism or agent that can produce disease. A pathogen may also be referred to as an infectious agent, or simply a ger ...
s, and tissue
ischemia
Ischemia or ischaemia is a restriction in blood supply to any tissue, muscle group, or organ of the body, causing a shortage of oxygen that is needed for cellular metabolism (to keep tissue alive). Ischemia is generally caused by problems ...
. It is the efferent, or motor arm of the
inflammatory reflex, the neural circuit that responds to and regulates the inflammatory response.
Regulating the immune response
In 1987, a study showed that administration of
armin
Armin (Armyn) is a given name or surname, and is:
* An ancient Indo-European name:
** a German/Dutch given name,
*** a modern form of the name Arminius (18/17 BC–AD 21), a German prince who defeated a Roman army in the Battle of the Teutoburg F ...
, an irreversible inhibitor of
acetylcholinesterase
Acetylcholinesterase (HGNC symbol ACHE; EC 3.1.1.7; systematic name acetylcholine acetylhydrolase), also known as AChE, AChase or acetylhydrolase, is the primary cholinesterase in the body. It is an enzyme that catalyzes the breakdown of acety ...
, by injection 24 hours before
sepsis
Sepsis, formerly known as septicemia (septicaemia in British English) or blood poisoning, is a life-threatening condition that arises when the body's response to infection causes injury to its own tissues and organs. This initial stage is foll ...
modelling invoked essential depression of a lethality of mice from experimental infectious process.
Later (in 1995) this data has been confirmed at cholinergic stimulation by other cholinomimetics.
Inhibitors of
acetylcholinesterase
Acetylcholinesterase (HGNC symbol ACHE; EC 3.1.1.7; systematic name acetylcholine acetylhydrolase), also known as AChE, AChase or acetylhydrolase, is the primary cholinesterase in the body. It is an enzyme that catalyzes the breakdown of acety ...
can cause higher accessibility of acetylcholine and activation of cholinergic anti-inflammatory pathway as well.
Tumor necrosis factors (
TNF
Tumor necrosis factor (TNF, cachexin, or cachectin; formerly known as tumor necrosis factor alpha or TNF-α) is an adipokine and a cytokine. TNF is a member of the Tumor necrosis factor superfamily, TNF superfamily, which consists of various tra ...
) (and other
cytokines) are produced by cells of the
innate immune system
The innate, or nonspecific, immune system is one of the two main immunity strategies (the other being the adaptive immune system) in vertebrates. The innate immune system is an older evolutionary defense strategy, relatively speaking, and is th ...
during local injury and infection. These contribute to initiating a cascade of mediator release, and recruiting inflammatory cells to the site of infection to contain infection, referred to as "
innate immunity
The innate, or nonspecific, immune system is one of the two main immunity strategies (the other being the adaptive immune system) in vertebrates. The innate immune system is an older evolutionary defense strategy, relatively speaking, and is th ...
.". TNF amplifies and prolongs the inflammatory response by activating other cells to release
interleukin-1
The Interleukin-1 family (IL-1 family) is a group of 11 cytokines that plays a central role in the regulation of immune and inflammatory responses to infections or sterile insults.
Discovery
Discovery of these cytokines began with studies on ...
(IL-1),
high mobility group
High-Mobility Group or HMG is a group of chromosomal proteins that are involved in the regulation of DNA-dependent processes such as
transcription, replication, recombination, and DNA repair.
Families
The HMG proteins are subdivided into 3 super ...
B1 (
HMGB1
High mobility group box 1 protein, also known as high-mobility group protein 1 (HMG-1) and amphoterin, is a protein that in humans is encoded by the ''HMGB1'' gene.
HMG-1 belongs to the high mobility group and contains a HMG-box domain.
Funct ...
) and other cytokines.
These inflammatory cytokine responses confer protective advantages to the host at the site of
bacterial infection
Pathogenic bacteria are bacteria that can cause disease. This article focuses on the bacteria that are pathogenic to humans. Most species of bacteria are harmless and are often beneficial but others can cause infectious diseases. The number of th ...
. A “beneficial” inflammatory response is limited, resolves in 48–72 hours, and does not spread systemically. The cholinergic anti-inflammatory pathway provides a braking effect on the innate immune response which protects the body against the damage that can occur if a localized inflammatory response spreads beyond the local tissues, which results in toxicity or damage to the
kidney
The kidneys are two reddish-brown bean-shaped organs found in vertebrates. They are located on the left and right in the retroperitoneal space, and in adult humans are about in length. They receive blood from the paired renal arteries; bloo ...
,
liver
The liver is a major organ only found in vertebrates which performs many essential biological functions such as detoxification of the organism, and the synthesis of proteins and biochemicals necessary for digestion and growth. In humans, it ...
,
lungs
The lungs are the primary organs of the respiratory system in humans and most other animals, including some snails and a small number of fish. In mammals and most other vertebrates, two lungs are located near the backbone on either side of ...
, and other organs.
Neurophysiological and immunological mechanism
The
vagus nerve
The vagus nerve, also known as the tenth cranial nerve, cranial nerve X, or simply CN X, is a cranial nerve that interfaces with the parasympathetic control of the heart, lungs, and digestive tract. It comprises two nerves—the left and rig ...
is the tenth
cranial nerve
Cranial nerves are the nerves that emerge directly from the brain (including the brainstem), of which there are conventionally considered twelve pairs. Cranial nerves relay information between the brain and parts of the body, primarily to and f ...
. It regulates
heart rate
Heart rate (or pulse rate) is the frequency of the heartbeat measured by the number of contractions (beats) of the heart per minute (bpm). The heart rate can vary according to the body's physical needs, including the need to absorb oxygen and e ...
,
broncho-constriction, digestion, and the innate immune response. The vagus nerve innervates the celiac ganglion, the site of origin of the splenic nerve. Stimulation of the efferent vagus nerve slows heart rate, induces
gastrointestinal motility Gastrointestinal physiology is the branch of human physiology that addresses the physical function of the gastrointestinal (GI) tract. The function of the GI tract is to process ingested food by mechanical and chemical means, extract nutrients and ...
, and inhibits
TNF
Tumor necrosis factor (TNF, cachexin, or cachectin; formerly known as tumor necrosis factor alpha or TNF-α) is an adipokine and a cytokine. TNF is a member of the Tumor necrosis factor superfamily, TNF superfamily, which consists of various tra ...
production in spleen.
Stimulation of the efferent pathway of the vagus nerve releases acetylcholine, the neurotransmitter which interacts with the α7 subunit of the
nicotinic AChR (α7 nAChR). nAChR is expressed on the
cell membrane
The cell membrane (also known as the plasma membrane (PM) or cytoplasmic membrane, and historically referred to as the plasmalemma) is a biological membrane that separates and protects the interior of all cells from the outside environment (the ...
of
macrophages and other
cytokine
Cytokines are a broad and loose category of small proteins (~5–25 kDa) important in cell signaling. Cytokines are peptides and cannot cross the lipid bilayer of cells to enter the cytoplasm. Cytokines have been shown to be involved in a ...
secreting cells. Binding of acetylcholine to nAChR activates intracellular signal transduction which inhibits the release of pro-inflammatory cytokines. Ligand receptor signaling does suppress production of anti-inflammatory cytokines (IL-10).
Relationship with psychological stress
Inflammatory markers tend to be elevated in people who experience various forms of
psychological stress
In psychology, stress is a feeling of emotional strain and pressure. Stress is a type of psychological pain. Small amounts of stress may be beneficial, as it can improve athletic performance, motivation and reaction to the environment. Excess ...
.
Psychological stress increases activation in the sympathetic branch of the
autonomic nervous system (ANS) resulting in increased adrenergic input to the spleen via sympathetic nerve fibers descending into lymphoid tissues.
The main neural structure responsible for down-regulating psychological stress levels is the
prefrontal cortex
In mammalian brain anatomy, the prefrontal cortex (PFC) covers the front part of the frontal lobe of the cerebral cortex. The PFC contains the Brodmann areas BA8, BA9, BA10, BA11, BA12, BA13, BA14, BA24, BA25, BA32, BA44, BA45, BA ...
(PFC). The PFC counters sympathetic nervous system activation by inhibiting arousal-eliciting activity in pre-autonomic neural structures such as the
amygdala
The amygdala (; plural: amygdalae or amygdalas; also '; Latin from Greek, , ', 'almond', 'tonsil') is one of two almond-shaped clusters of nuclei located deep and medially within the temporal lobes of the brain's cerebrum in complex v ...
and
hypothalamus
The hypothalamus () is a part of the brain that contains a number of small nuclei with a variety of functions. One of the most important functions is to link the nervous system to the endocrine system via the pituitary gland. The hypothalamus ...
and by increasing activity in the vagal branch of the ANS.
Thus, the prefrontal input to the ANS modulate the inflammatory response to psychological stress in part via the cholinergic anti-inflammatory pathway.
In recent years, this PFC-Vagus Nerve-Spleen axis has been linked to
cellular senescence
Cellular senescence is a phenomenon characterized by the cessation of cell division. In their experiments during the early 1960s, Leonard Hayflick and Paul Moorhead found that normal human fetal fibroblasts in culture reach a maximum of approxi ...
and various pathologies such as
neurodegenerative diseases and
cancer
Cancer is a group of diseases involving abnormal cell growth with the potential to invade or spread to other parts of the body. These contrast with benign tumors, which do not spread. Possible signs and symptoms include a lump, abnormal bl ...
.
See also
Branches of medicine
*
Behavioral neuroscience
*
Biological psychiatry
Biological psychiatry or biopsychiatry is an approach to psychiatry that aims to understand mental disorder in terms of the biological function of the nervous system. It is interdisciplinary in its approach and draws on sciences such as neuroscie ...
*
Epidemiology
Epidemiology is the study and analysis of the distribution (who, when, and where), patterns and determinants of health and disease conditions in a defined population.
It is a cornerstone of public health, and shapes policy decisions and evide ...
*
Immunology
Immunology is a branch of medicineImmunology for Medical Students, Roderick Nairn, Matthew Helbert, Mosby, 2007 and biology that covers the medical study of immune systems in humans, animals, plants and sapient species. In such we can see ther ...
*
Molecular biology
Molecular biology is the branch of biology that seeks to understand the molecular basis of biological activity in and between cells, including biomolecular synthesis, modification, mechanisms, and interactions. The study of chemical and phys ...
*
Neuroanatomy
Neuroanatomy is the study of the structure and organization of the nervous system. In contrast to animals with radial symmetry, whose nervous system consists of a distributed network of cells, animals with bilateral symmetry have segregated, defin ...
*
Neurobiology
Neuroscience is the scientific study of the nervous system (the brain, spinal cord, and peripheral nervous system), its functions and disorders. It is a multidisciplinary science that combines physiology, anatomy, molecular biology, developmen ...
*
Neurochemistry
Neurochemistry is the study of chemicals, including neurotransmitters and other molecules such as psychopharmaceuticals and neuropeptides, that control and influence the physiology of the nervous system. This particular field within neuroscience e ...
*
Neurophysics
*
Neurology
Neurology (from el, νεῦρον (neûron), "string, nerve" and the suffix -logia, "study of") is the branch of medicine dealing with the diagnosis and treatment of all categories of conditions and disease involving the brain, the spinal ...
*
Neuropharmacology
Neuropharmacology is the study of how drugs affect function in the nervous system, and the neural mechanisms through which they influence behavior. There are two main branches of neuropharmacology: behavioral and molecular. Behavioral neuropharmac ...
*
Psychiatry
Psychiatry is the medical specialty devoted to the diagnosis, prevention, and treatment of mental disorders. These include various maladaptations related to mood, behaviour, cognition, and perceptions. See glossary of psychiatry.
Initial p ...
*
Psychoneuroendocrinology
*
Psychoneuroimmunology
Psychoneuroimmunology (PNI), also referred to as psychoendoneuroimmunology (PENI) or psychoneuroendocrinoimmunology (PNEI), is the study of the interaction between psychological processes and the nervous and immune systems of the human body. It is ...
Related topics
*
Allostatic load
Allostatic load is "the wear and tear on the body" which accumulates as an individual is exposed to repeated or chronic stress. The term was coined by Bruce McEwen and Eliot Stellar in 1993. It represents the physiological consequences of chro ...
*
Cancer
Cancer is a group of diseases involving abnormal cell growth with the potential to invade or spread to other parts of the body. These contrast with benign tumors, which do not spread. Possible signs and symptoms include a lump, abnormal bl ...
*
Cellular senescence
Cellular senescence is a phenomenon characterized by the cessation of cell division. In their experiments during the early 1960s, Leonard Hayflick and Paul Moorhead found that normal human fetal fibroblasts in culture reach a maximum of approxi ...
*
Fight-or-flight response
The fight-or-flight or the fight-flight-or-freeze response (also called hyperarousal or the acute stress response) is a physiological reaction that occurs in response to a perceived harmful event, attack, or threat to survival. It was first desc ...
*
Healing environments
Healing environment, for healthcare buildings describes a physical setting and organizational culture that supports patients and families through the stresses imposed by illness, hospitalization, medical visits, the process of healing, and someti ...
*
Heart rate variability
Heart rate variability (HRV) is the physiological phenomenon of variation in the time interval between heartbeats. It is measured by the variation in the beat-to-beat interval.
Other terms used include: "cycle length variability", "R–R variabi ...
*
Immuno-psychiatry Immuno-psychiatry, according to Pariante, is a discipline that studies the connection between the brain and the immune system. It differs from psychoneuroimmunology by postulating that behaviors and emotions are governed by peripheral immune mechani ...
*
Infectious diseases
An infection is the invasion of tissues by pathogens, their multiplication, and the reaction of host tissues to the infectious agent and the toxins they produce. An infectious disease, also known as a transmissible disease or communicable d ...
*
Inflammatory reflex
*
Neural top down control of physiology
*
Neurodegenerative diseases
*
PANDAS
Pediatric autoimmune neuropsychiatric disorders associated with streptococcal infections (PANDAS) is a controversial hypothetical diagnosis for a subset of children with rapid onset of obsessive-compulsive disorder (OCD) or tic disorders. Sy ...
*
Post-traumatic stress disorder
Post-traumatic stress disorder (PTSD) is a mental and behavioral disorder that can develop because of exposure to a traumatic event, such as sexual assault, warfare, traffic collisions, child abuse, domestic violence, or other threats on a ...
*
Psychosomatic medicine
Psychosomatic medicine is an interdisciplinary medical field exploring the relationships among social, psychological, behavioral factors on bodily processes and quality of life in humans and animals.
The academic forebear of the modern field of ...
*
Sepsis
Sepsis, formerly known as septicemia (septicaemia in British English) or blood poisoning, is a life-threatening condition that arises when the body's response to infection causes injury to its own tissues and organs. This initial stage is foll ...
*
Somatic marker hypothesis
The somatic marker hypothesis, formulated by Antonio Damasio and associated researchers, proposes that emotional processes guide (or bias) behavior, particularly decision-making. ''Descartes' Error''
"Somatic markers" are feelings in the body th ...
*
Stress management
Stress management is a wide spectrum of techniques and psychotherapies aimed at controlling a person's level of stress, especially chronic stress, usually for the purpose of and for the motive of improving everyday functioning. Stress produces ...
Neuroanatomy
*
Amygdala
The amygdala (; plural: amygdalae or amygdalas; also '; Latin from Greek, , ', 'almond', 'tonsil') is one of two almond-shaped clusters of nuclei located deep and medially within the temporal lobes of the brain's cerebrum in complex v ...
*
Hypothalamus
The hypothalamus () is a part of the brain that contains a number of small nuclei with a variety of functions. One of the most important functions is to link the nervous system to the endocrine system via the pituitary gland. The hypothalamus ...
*
Prefrontal cortex
In mammalian brain anatomy, the prefrontal cortex (PFC) covers the front part of the frontal lobe of the cerebral cortex. The PFC contains the Brodmann areas BA8, BA9, BA10, BA11, BA12, BA13, BA14, BA24, BA25, BA32, BA44, BA45, BA ...
*
Solitary nucleus
In the human brainstem, the solitary nucleus, also called nucleus of the solitary tract, nucleus solitarius, and nucleus tractus solitarii, (SN or NTS) is a series of purely sensory
nuclei (clusters of nerve cell bodies) forming a vertical column ...
*
Splenic plexus
The splenic plexus (lienal plexus in older texts) is formed by branches from the celiac plexus, the left celiac ganglion, and from the right vagus nerve.
It accompanies the lienal artery to the spleen
The spleen is an organ found in almost ...
*
Vagus nerve
The vagus nerve, also known as the tenth cranial nerve, cranial nerve X, or simply CN X, is a cranial nerve that interfaces with the parasympathetic control of the heart, lungs, and digestive tract. It comprises two nerves—the left and rig ...
Neurotransmitter Pathways
*
List of regions in the human brain § Neurotransmitter pathways
References
{{Reflist
Immunology
Neurophysiology
Psychoneuroimmunology