Autoimmunity is a condition in which the body’s immune system, which is responsible for protecting it from foreign bodies and pathogens, loses control and begins to attack its own cells. Let us first understand how the immune system works normally. Our body has two types of mechanisms to protect us against an infection.
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Cell Mediated Protection
Few types of large cells are present in our body namely macrophages, neutrophils, and dendritic cells, mast cells, eosinophils, basophils, and natural killer cells. These cells are programmed to kill foreign body as and when they come into contact with one. The common mechanism of killing involves engulfing, sucking the foreign body and then killing it with the help of various enzymes. The phagocytes form the base of what is the Innate Immunity and are present at birth. Other forms of innate immunity include surface barriers such as the presence of killer enzymes in saliva.
Our body may already have antibodies against the known pathogens. When these pathogens enter the bloodstream, antibodies can eliminate them through three different ways. First, the antibody may completely cover the foreign particle. Second, the antibody can act as a watchdog, and activate other cells that kill the foreign body. Third, the antibody may attach to the foreign body, which allows other guard cells to engulf the pathogen. This type of immune system is referred to as an Adaptive Immunity. The word adaptive indicates the ability of the body to develop new antibody when it comes into contact with a new disease pathogen.
Adaptive or antibody-based protection process is most susceptible to the development of autoimmune diseases. Many complexities are still unsolved as to why body mistakenly learns to attack its cells. Autoimmune diseases variety is mind-boggling. Research suggests over 80 types that vary from each other based on the body part they attack, whereas some have a system wide impact.
While individual diseases by itself are rare, collectively, if all autoimmune diseases are combined, they affect roughly 5-8% of the human population. Several variations are also seen between ethnic races. For instance, Type 1 diabetes is more commonly seen in the white or Caucasian race, whereas Lupus is seen more in the African-American and Hispanic race. In terms of gender, autoimmune diseases are also more prevalent in women than men. Estimates suggest that nearly 80% of individuals with the autoimmune disease are women.
Cause of Autoimmune Diseases
Autoimmune diseases are known to be polygenic i.e. persons who acquire an autoimmune disease have a family of genes that have some mutation or defect. However, every person who has such genes may not have the disease. However, heredity alone accounts for only 30% risk of getting the disease, with the remaining 70% risk attributed to environmental factors such as hormones, diet, drugs, toxins exposure, and infections.
Hormones, especially sex-related hormones such as estrogen and androgen are known to amplify the immune response. Women either produce more of these naturally or have a higher synthetic intake in the form of birth control pills.
Components in our diets may also contribute to the development of autoimmunity. The presence of pesticides albeit within safe limits may still trigger. In some individuals, gluten may trigger an autoimmune response. Excess intake of Iodine through Iodized products is believed to increase the autoimmune disease related to Thyroid gland. The presence of heavy metals such as mercury, silver or gold is found to induce an autoantibody response in laboratory tests.
Viral and bacterial infections are also known to trigger autoimmunity. Several different mechanisms as to how infections can trigger the disease are cited in medical research and laboratory tests in animals prove some.
Autoimmune Damage Mechanism
Antibody assisted damage includes the presence of autoantibody which binds to healthy cells and induces a response by other immune cells, resulting in lysis of the healthy cell. Alternatively, they can also bind to a healthy cell surface and alter its functioning. Presence of specific autoantibody is a good predictor of a particular disease type.
When there is an overabundance of specific immune cell types called T-helper cells, it signifies that immune system is in a hyperactive mode. These cells secrete certain chemicals called Cytokines that invite the macrophages to arrive and destroy even healthy cells.
Another mechanism that can cause autoimmunity is when the regulatory cells which prevent body’s immune system from going into a hyper-drive become ineffective. Due to this mechanism, sometimes the absence of an autoantibody is not enough to rule out a particular autoimmune disease.
The Autoimmune Disease Challenge
Autoimmune diseases are often very challenging to diagnose even for the most experienced physicians. When a particular autoantibody is present, it does not always imply that the person has a disease, but it is a good indication of his or her susceptibility to a disease.
When autoimmunity is caused by ineffective regulatory cells, it is hard to diagnose an autoimmune disease. In such cases, physicians rely on the symptoms that differentiate a disease from others. However, symptoms too sometimes overlap or take much longer to manifest in a form that makes the disease type clear to the physician.
Another challenge with autoimmune diseases is that different diseases impact various parts of a human body. Therefore, if one has multiple sclerosis, a neurologist would need to be involved. Likewise, if someone has Rheumatoid Arthritis, a rheumatologist must be involved. Multiple opinions may sometime be necessary to analyze the disease symptoms and get closer to diagnosing the disease.
Major Disease Types and Impact Area
There are over eighty different autoimmune diseases, and they can be categorized into 2 general types:
- Localized (organ specific) – mainly one particular part of the body affected
- Systemic – multiple regions of the body affected
A person may suffer from multiple different types of autoimmune diseases, causing an overlap of symptoms.
Types of localized (organ specific) autoimmune diseases:
- Diabetes Mellitus Type 1a (pancreas)
- Autoimmune hepatitis (liver)
- Addison’s disease (adrenal)
- Coeliac disease (gastrointestinal tract)
- Crohn’s disease (gastrointestinal tract)
- Primary biliary cirrhosis (liver)
- Myasthenia gravis (nerves, muscles)
- Ulcerative colitis (gastrointestinal tract)
- Guillain-Barre syndrome (nervous system)
- Hashimoto’s thyroiditis
- Multiple sclerosis (nervous system)
- Pernicious anemia (stomach)
- Grave’s disease (thyroid)
- Sclerosing cholangitis (liver)
Systemic autoimmune diseases:
Systemic autoimmune diseases can affect many organs of body and tissues at the same time.
This can be broadly classified into:
- Rheumatological/connective tissue disease
- Vasculitis (inflammation of blood vessels)
Types of rheumatological systemic autoimmune diseases:
- Antiphospholipid antibody syndrome (multiple organs due to a blood clotting disorder)
- Dermatomyositis (muscles, skin)
- Polymyalgia rheumatica (large group muscle – pain, stiffness and inflammation in the muscles around the shoulders, neck and hips)
- Polymyositis (muscles, skin)
- Scleroderma (skin, intestine, less commonly lungs, kidneys)
- Sjögren’s syndrome (salivary glands, joints, tear glands)
- Primary Raynaud’s disease (blood vessels – spasm of the arteries in the extremities, especially the fingers)
- Rheumatic fever
- Rheumatoid arthritis (joints, less commonly lungs, eyes, skin)
- Systemic Lupus Erythematosus which affects kidneys, heart, brain, red blood cells and skin
Diagnosis of autoimmune diseases:
Autoimmune diseases are difficult to diagnose. The presence of an autoantibody can indicate the disease type or susceptibility of an individual for a particular type. However, as mentioned earlier, every individual who has a particular autoantibody need not have the disease symptoms. Autoimmunity also relies on other mechanisms which are not dependent on the presence of autoantibody. In such cases, it is even harder to diagnose a disease through laboratory tests alone. In such situations, physicians have to rely often on making an educated and experience based guess on the basis of the disease symptoms, clinical history, blood tests for inflammation and organ function. Biopsy of the affected tissues may be helpful as well as other investigations such as X-rays for diseases that affect the joints, such as the Rheumatoid Arthritis.
At present, there are no complete cures for the autoimmune diseases. Therefore, treatment objectives
- To relieve the symptoms
- To minimize organ and tissue damage
- To preserve organ function
Treatments of choice for autoimmune disease (usually under specialist supervision), include one or more of:
- NSAIDS(Non-steroidal anti-inflammatory medications)
- Replenishment for deficiency caused by disease (such as insulin in diabetes and thyroxine in autoimmune thyroid disease)
- Immunosuppressive medications
- Corticosteroid anti-inflammatory medications (such as Prednisolone)
- Immunoglobulin replacement therapy
- Physiotherapy to help with movement if the bones, joints, or muscles are affected
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