Autoimmune disease occurs when the regulatory mechanism of the immune system in an individual fails and that causes the immune system to attack self-antigens. Such individuals will make autoantibodies or cytotoxic T cells against their own cells and cause destruction that is mostly accompanied by very intense inflammation.
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An Analogy of An Autoimmune Disease
We already explained on our homepage that your immune system acts like your dog at home. Your dog attacks unknown people and protects those that are known including yourself, your spouse, and your brothers, and sisters among others. In the same way, your immune system attacks antigens that are unknown to it and protects those antigens that belong to your body.
In autoimmunity, your immune system like a dog with rabies gets ‘mad’ and is unable to distinguish self-antigens from foreign ones. As a result, the immune system attacks your cells causing autoimmunity which gives rise to autoimmune diseases. These diseases can be organ-specific or systemic.
Research has demonstrated that autoimmune diseases are more common among women than men. However, the reason for this occurrence is not known. The exact triggers of autoimmune diseases are also unknown.
Some of the possible causes include:
Where there is a molecular similarity between microorganism antigens and cellular antigens, then it follows that when the immune system mounts an immune response (antibodies) against such microorganisms the same antibodies can bind in a specific way to the human cells. This will cause the cells to be destroyed by other components of the immune system like the phagocytes and the complement fragments.
There are some cells that may cross from the mother to the fetus through the placenta. Such cells are likely to cause autoimmune disease later in the life of such an individual.
Research has also hypothesized that estrogen can trigger the destruction of cells by CD8+ T cells. Estrogen is thought to control the immune system by regulating cellular metabolism through some receptors like ERα and ERβ.
Individuals may have hidden antigens. If such antigens are ‘seen’ by the immune system they may be treated as foreign because no tolerance has been developed for them in the past. They will therefore be destroyed in an autoimmune response.
Exposure to certain environmental factors including some viral infections may cause autoimmunity. This has been hypothesized to be one of the causes of autoimmune diseases.
Failure of the regulatory mechanisms
The immune system has control mechanisms like the CD25+ T regulatory cells that limit the immune response to foreign antigens when such a response is unnecessary. This ensures that the immune response is switched off once the antigens are cleared. If such a regulatory mechanism fails then there will be autoimmunity.
The inherited MHC genes may be of a type that causes autoimmunity along familial lines. That means that there may be a higher probability to have an autoimmune disorder if one comes from a family where someone suffered an autoimmune system in the past.
Types of Autoimmune Diseases
Autoimmune diseases are of two types. Systemic autoimmune diseases and single-organ autoimmune diseases. Single-organ autoimmune disorders affect a specific organ like diabetes mellitus type 1 affects the pancreas. The anti-beta cell autoantibodies are formed and destroy only the pancreas.
On the other hand, systemic autoimmune disorders involve the whole body. A good example here is the systemic lupus erythematosus which forms autoantibodies that can mediate the destruction of several tissues in the body.
Common Autoimmune disorders
In this disease, the immune system makes anti-thyroid gland antibodies. These antibodies attack the thyroid gland where they will mostly cause overstimulation of the gland making it produce an excess of its hormones like T3, T4, and TSH.
This causes excessive metabolic activities in the body. The most common symptom of this disease is the bulging of the eyes and the inability to align both the eyes to a specific spot.
This autoimmune disease affects the thyroid gland. The immune system produces anti-thyroid peroxidase antibodies that cause the gland to have massive inflammation. This may destroy some parts of the gland and make it unable to produce enough T3 and T4 hormones. However, laboratory findings have shown that TSH levels are elevated.
This autoimmune disease is characterized by a lack of vitamin B-12. The immune system destroyed the cells of the stomach lining that produce intrinsic factors. This protein makes it possible for the body to absorb vitamin B-12 from the diet. Lack of vitamin B-12 causes anemia.
Systemic Lupus Erythematosus (SLE)
This is a systemic disorder that may affect many organs in the body. Autoantibodies are detected using a laboratory test called the Anti-Nuclear Antibody test. Examples of organs that can be attacked through the mediation of the produced autoantibodies include the kidneys, heart, brain, and joints among others. The common symptoms include a general body rash, joint pains, and lethargy among others.
Type 1 Diabetes Mellitus
This autoimmune disorder causes the body to be unable to produce both insulin and glucagon. Insulin downregulates glucose whenever it goes beyond the norm while glucagon upregulates glucose in the blood.
The two hormones are produced by the beta cells of the pancreas. During DM type 1 the immune system produces autoantibodies that mediate the destruction of the pancreas. This is diagnosed by measuring the random blood sugar and detection of the antibodies in the pancreas and in the blood.
Rheumatoid Arthritis (RA)
This is a systemic autoimmune disease that is characterized by debilitating pain in the joints throughout the body. It is also characterized by the presence of autoantibodies called rheumatoid factors (RF) in the blood. The RF can help in making a generic diagnosis of RA before other ways (e.g., clinical manifestation, X-rays) of making a specific diagnosis can be employed.
There is very intense inflammation in RA, and this is driven by pro-inflammatory cytokines like TNF, IL-1, IL-6, IL-8, and IL-13. To detect elevation of these cytokines, laboratories can procure inflammation panel which also includes other players of inflammation including the complement mediators (C3a and C5a). Alternatively, you could procure Th1 Th2 Th17 cytokine test kit and achieve the same goal.
Other detected this cytokine-driven inflammation should be controlled before it becomes chronic. Chronic inflammation will, in the long run, cause destruction of the joints’ cartilage tissues and make them lose the flexibility to become very stiff which can cause problems with mobility.
Multiple Sclerosis (MS)
This autoimmune disease causes damage to the myelin sheath that surrounds nerve cells. Because myelin sheath surrounds the nerves that line the brain and the spinal cord, their damage affects the speed of the nerve impulse transmission in the entire body. This damage is immune-mediated. The common symptoms include numbness, general body weakness, and difficulty in walking.
This disorder is caused by the intolerance of your body to gluten-containing foods. Such foods include wheat and grain products. As gluten-containing food passes through the gut, the immune system mounts an inflammatory response that leads to the destruction of cells of the small intestines.
Addison’s Autoimmune Disease
This is an autoimmune disease in which the immune system produces autoantibodies that mediate the damage to the adrenal glands. The adrenal glands produce hormones like aldosterone, cortisol, and androgens. Each of these hormones is critical in the normal function of the body.
For instance, a lack of enough cortisol may affect the utilization of glucose in the body. A deficiency in the level of aldosterone may cause an imbalance of sodium and potassium in the intracellular and extracellular fluid compartments. Its symptoms include general malaise, weight loss, and low blood glucose.
Myasthenia Gravis (MG)
This autoimmune disease is characterized by a loss of muscle tone. The reason for this is that nerve impulse transmission is impaired. The patient becomes very weak, barely able to control simple things like facial movements, eye movements, and swallowing.
Autoimmunity is caused by the failure of the regulatory mechanisms of the immune system. The cells of your immune system attack your own body. Autoimmune disorders are characterized by intense inflammation that ultimately causes cell damage.Follow us on Social Media