There are so many autoimmune disorders that I want to write posts about this year. Most of them I have never heard of, and today’s autoimmune disorder/disease autoimmune angioedema is no exception.
There are two types of angioedema: hereditary or acquired. Acquired angiodema is the type I’m writing about today. It can develop with systemic lupus erythematosus (lupus) or dermatomyositis.
What is Autoimmune Angioedema?
It is clinically characterized by recurrent episodes of non-pitting asymmetric edema of the face, lips, tongue, limbs, and genitals; severe abdominal pain due to edema of the gastrointestinal mucosa; and life-threatening edema of the upper respiratory tract.
Let’s break this definition down.
What is edema? A condition characterized by an excess of watery fluid collecting in the cavities or tissues of the body.
What is non-pitting edema? When pressure is applied to the area where there is watery fluid, no indentation is made in the skin.
Asymmetric means that the fluid is collecting evenly.
What is the gastrointestinal mucosa? The gastric mucosa is the mucous membrane layer of the stomach which contains the glands and the gastric pits. In humans it is about 1 mm thick and its surface is smooth, soft, and velvety.
Acquired angioedema, a rare disorder, differs from hereditary angioedema. It develops when certain cancers, such as lymphoma, or autoimmune disorders, such as systemic lupus erythematosus (lupus) or dermatomyositis, cause a deficiency of C1 inhibitor. Symptoms usually start later in life, after people have developed a disorder that can cause this deficiency.
In both hereditary and acquired angioedema, swelling (angioedema) may be triggered by:
- A minor injury, as may occur during a dental procedure
- A viral infection
- Certain foods
- Exposure to cold
Stress, such as that due to anticipating or having a dental or surgical procedure, can make angioedema worse.
C1–inhibitor (C1-inh, C1 esterase inhibitor) is a protease inhibitor belonging to the serpin superfamily. Its main function is the inhibition of the complement system to prevent spontaneous activation.
What is protease? An enzyme that breaks down proteins and peptides.
What is a protease inhibitor? A substance that breaks down protease, thereby inhibiting the replication of certain cells and viruses, including HIV.
What is a serpin? Serpins are a superfamily of proteins with similar structures that were first identified for their protease inhibition activity and are found in all kingdoms of life.
What is a complement system? The complement system is a part of the immune system that enhances the ability of antibodies and phagocytic cells (a cell,that has the ability to engulf and destroy pathogens, waste material, and other particulate matter.) to clear microbes and damaged cells from an organism, promotes inflammation, and attacks the pathogen’s cell membrane.
Swelling may occur in the:
- the back of the hands or feet
- and/or other areas of the body may swell
- as may the membranes lining the mouth, throat, airways, and digestive tract.
Typically, the swollen areas are slightly painful, not itchy. Hives do not appear. Nausea, vomiting, and cramps are common.
Swelling in the voice box (larynx), throat, or tongue can interfere with breathing. People may make a gasping sound when they breathe in.
- Drugs such as ecallantide or purified C1 inhibitor
- Fresh frozen plasma
Drugs to prevent future attacks
Certain drugs, such as ecallantide or purified C1 inhibitor (which is derived from human blood), can sometimes relieve the swelling. However, these drugs are not always available. In such cases, fresh frozen plasma or, in the European Union, tranexamic acid may be given. Antihistamines and corticosteroids are not effective.
Pain relievers, drugs to relieve nausea (antiemetic drugs), and fluids may help relieve symptoms.