Lesser known mast cell mediators (Part 2)

Arylsulfatase A, also called cerebroside sulfatase, breaks down compounds to yield cerebrosides and sulfates. Cerebrosides can be either galactocerebrosides, which are found in all tissues of the nervous system; or glucocerebrosides, which are found in the skin, spleen, red blood cells and, to a lesser extent, tissues of the nervous system.

Arylsulfatase B, which has several other names, breaks down large sugar compounds, especially dermatan sulfate and chondroitin sulfate. Arylsulfatase B is mostly found in the liver, pancreas and kidneys.

Mutations in the gene for either arylsulfatase can lead to a variety of heritable disorders, including mucopolysaccharidosis VI and metachromatic leukodystrophy.

Chymases include mast cell protease 1, mast cell serine proteinase, skeletal muscle protease and so on. They are found almost exclusively in mast cells, but are present in small amounts in the granules of basophils. They have several functions, including generating an inflammatory response to parasites. They convert angiotension I to angiotensin II and therefore impact hypertension and atherosclerosis.

Bradykinin causes dilation of blood vessels, which induces a corresponding drop in blood pressure. It achieves its action by triggering release of prostacyclin, nitric oxide and endothelium derived hyperpolarizing factor. It also causes contraction of non-vascular smooth muscles in the respiratory and GI tracts, and is involved in the way the body senses pain. Bradykinin is important in angioedema.

Angiogenin, also called ribonuclease 5, stimulates the formation of new blood vessels. It drives the degradation of the basement membrane and local matrix so that endothelial cells can move toward the vascular spaces.

Leptin is the hormone that regulates hunger. It is mostly produced by fat cells, but is released by mast cells as well. When a specific amount of fat is stored in the body, leptin is secreted and tells the brain that it is full. It opposes the action of ghrelin, the hormone that tells your body it is hungry.

Renin, also called angiotensinogenase, is a critical component of the renin-angiotension system (RAS) that controls the volume of fluids not in cells, including blood plasma, lymph and interstitial fluid. It regulates the body’s mean arterial blood pressure. It converts angiotensinogen to angiotensin I.

Somatostatin, also growth hormone inhibiting hormone (GHIH), regulates the endocrine system, transmission of neurologic signals and cell growth by acting on somatostatin receptors and inhibiting the release of various secondary hormones. It inhibits secretion of glucagon and insulin. It is secreted throughout the GI system and decreases stomach acid production by downregulating the release of gastrin, secretin and histamine.