Mast cell

A mast cell is a type of white blood cell that protects the body from immune threats by promoting inflammation. Mast cells are present in all tissues. They are most commonly known for their role in the immune system of mucosal membranes; however, they are necessary in maintaining basic human health and defending against pathogens.

When a mast cell encounters a perceived immune threat, pro-inflammatory mediators are released through a process known as degranulation. Some anti-inflammatory mediators may include histamine, cytokines, proteases, or heparin.

Mast cell activation

Degranulation

Mast cells can become activated when they encounter a foreign substance. A cascade response allows for degranulation to begin and a subsequent release of inflammatory granules into the bloodstream.

Mechanisms of inhibition

There are several proposed supplements or treatments that might grant temporary mast cell degranulation inhibition:

Antioxidants: these are substances that are considered to remove potentially harmful reactive oxygen species from the body. Vitamin C, vitamin A, vitamin E, and beta-carotene are examples of antioxidants. The properties of such antioxidants have been noted to be capable of reducing blood histamine levels. The exact mechanisms that cause blood histamine levels to decrease are still unknown. However, antioxidants have been noted to be capable of inhibiting mast cell production and altering the enzymes that form (diamine oxidase) or breakdown (histidine decarboxylase) histidine.

Phototherapy: UVA and UVA1 phototherapy has been observed to significantly inhibit histamine release from mast cells and other white blood cells.

Infection

Past findings have suggested that mast cell activation due to a viral infection may play part in initiating autoimmune disease. The Coxsackievirus infection has been observed to up-regulate toll-like receptor 4 (TLR4) on mast cells in mice, immediately following the period of infection.TLR4 up-regulation can have negative consequences on the immune system because TLR4 activation indirectly activates the innate immune system and the inflammatory response system.

Gastrointestinal Tract and the Nervous system

Mast cells are found within the nervous system and are capable of crossing the blood-brain barrier (this separates blood from the central nervous system). The gastrointestinal tract and the brain are capable of communicating through the blood brain barrier, also known as the gut-brain axis (GBA). Exchange of information between the central (brain) and peripheral (gut) nervous systems ensures that the stomach and intestines are communicating with the brain. "Immune activation, intestinal permeability, enteric reflex, and entero-endocrine signaling" are all influenced by the GBA. Therefore mast cells are likely a type of cell that indirectly affect neurological functioning when the gut is inflammed.

Role in human disease

Mast cell activation disorder

See full article: Mast cell activation disorder

Mast cell activation disorder (MCAD) is a condition in which mast cells are over-responsive to various environmental triggers. When mast cells are over-responsive the result can be an increase in the release histamine and other inflammatory molecules. Excessive inflammation can result from such a condition.

MCAD is often found in patients with Ehlers-Danlos syndrome (EDS) and postural orthostatic tachycardia syndrome (POTS), a form of orthostatic intolerance, two conditions commonly co-morbid with ME. The overlap between EDS, POTS, and MCAD is thought to be due to increased tryptase production owing to an extra copy of a gene called TPSAB .

MCAD should be distinguished from mastocytosis, a genetic disorder causing excessive production of mast cells.

Myalgic encephalomyelitis

Individuals diagnosed with moderate to severe ME have been noted to have higher amounts of dysfunctional mast cells in circulation.

Fibromyalgia

Over expression of mast cells has been observed in the skin of patients with fibromyalgia.

Notable studies

• 2017, Novel characterisation of mast cell phenotypes from peripheral blood mononuclear cells in chronic fatigue syndrome/myalgic encephalomyelitis patients (Full Text)

See also

• Mast cell activation disorder
• Theoharis Theoharides

membrane The word "membrane" can have different meanings in different fields of biology. In cell biology, a membrane is a layer of molecules that surround its contents. Examples of cell-biology membranes include the "cell membrane" that surrounds a cell, the "mitochondrial membranes" that form the outer layers of mitochondria, and the "viral envelope" that surrounds enveloped viruses. In anatomy or tissue biology, a membrane is a barrier formed by a layer of cells. Examples of anatomical membranes include the pleural membranes that surrounds the lungs, the pericardium which surrounds the heart, and some of the layers within the blood-brain barrier.

β β / Β. Greek letter beta (a symbol used in science), equivalent to "b".

enzyme a substance produced by a living organism which acts as a catalyst to bring about a specific biochemical reaction.

central nervous system (CNS) - One of the two parts of the human nervous system, the other part being the peripheral nervous system. The central nervous system consists of the brain and spinal cord, while the peripheral nervous system consists of nerves that travel from the central nervous system into the various organs and tissues of the body.

postural orthostatic tachycardia syndrome (POTS) - A form of orthostatic intolerance where the cardinal symptom is excessive tachycardia due to changing position (e.g. from lying down to sitting up).

myalgic encephalomyelitis (M.E.) - A disease often marked by neurological symptoms, but fatigue is sometimes a symptom as well. Some diagnostic criteria distinguish it from chronic fatigue syndrome, while other diagnostic criteria consider it to be a synonym for chronic fatigue syndrome. A defining characteristic of ME is post-exertional malaise (PEM), or post-exertional neuroimmune exhaustion (PENE), which is a notable exacerbation of symptoms brought on by small exertions. PEM can last for days or weeks. Symptoms can include cognitive impairments, muscle pain (myalgia), trouble remaining upright (orthostatic intolerance), sleep abnormalities, and gastro-intestinal impairments, among others. An estimated 25% of those suffering from ME are housebound or bedbound. The World Health Organization (WHO) classifies ME as a neurological disease.

microbiome The full collection of microscopic organisms (especially bacteria and fungi) which are present in a particular environment, particularly inside the human body.

dysautonomia disorders of the autonomic nervous system that cause disturbances in all or some autonomic functions, may cause problems regulating autonomic functions, including heart rate, blood pressure, body temperature, and digestion. Can cause symptoms including lightheadedness, fainting, unstable blood pressure, and orthostatic intolerance.

phase one A drug trial involving only a small group of humans, often healthy volunteers, to assess drug safety and side effects. Typically 20-80 participants, often using a comparison group.