The autoimmune disease is in which the immune system triggers an aggressive response against a structure of the body. There are organ-specific diseases, which are limited to a particular organ or tissue, or systemic autoimmune diseases in which various organs or organ systems are involved. Autoimmune diseases affect about 7-8 percent of the total population.
Women have a genetic predisposition. Approximately 75 percent of the affected are female. The disease is often appearing in young, healthy people.
A combination of environmental factors also play a role in the development of autoimmune diseases, but the exact cause is unknown in most cases. Frequently, they occur cumulatively, meaning that a patient with an autoimmune disease may have another one after a certain period. They have a variety of symptoms and typically have a chronic course, some with life-threatening complications.
Autoimmune diseases can’t be cured permanently, but they can be treated more efficiently. Their therapy is primarily immunosuppressive drugs (immunosuppressants). Recently, some targeted biological therapies have also become available, which have proved to be effective in many often untreatable cases. Because treatments are often quite expensive, and the illness usually accompanies people throughout their lives, autoimmune diseases are a significant burden on healthcare systems.
Causes of autoimmune diseases
The development of autoimmune diseases are very complex and are not yet fully understood. The situation is further complicated by the fact that the causes may vary for each condition. Research has shown that certain environmental factors (such as infections) cause disease in individuals who are genetically susceptible to it. But in many cases, neither the exact mechanism of the disease nor the factors that lead to the cause are known. Since there may be a long time between the causative factor and the clinical appearance of the illness, it is virtually impossible to determine afterward what the exact cause was. The problem is that it is difficult to tell how many of the immunological abnormalities contribute to the onset of the disease.
There are several theories about the exact mechanisms of autoimmune diseases.
The molecular mimicry can be defined as the structural similarity between foreign (microbial) and self-molecules of the host. The theory is that some immune responses against some of the exogenous antigens (e.g., some proteins of the pathogens) cross-react with some of the body’s own structures. That is, lymphocytes recognizing foreign antigens partially recognize their own antigens and develop a non-discriminatory immune response against it. Which later, since its own antigen is permanently present does not stop and leads to self-sustaining autoimmune disease. Part of this explains why some infections can trigger the illness. Molecular mimicry is believed to be the cause of many autoimmune diseases, e.g., various food-induced immune responses, optic neuritis, or rheumatic fever.
Mechanisms that are dependent on the recognition of autoantigens may be important immunological triggers. Numerical or functional differences in T cells involved in the regulation of immune response and maintenance of immunological tolerance may also lead to autoimmune diseases.
It is known that some autoimmune diseases may accumulate in families. For example, Hashimoto’s thyroiditis, autoimmune hemolytic anemia. With few exceptions, all of them are linked to a specific HLA (human leukocyte antigen) specificity. For example, patients with type 1 diabetes have HLA-DR-3 or HLA-DR-4 variants, whereas the presence of the HLA-DR-2 variant works against the disease.
Mutations of genes essential for the development of immunological tolerance can also lead to autoimmune diseases. A good example is AIRE (Autoimmune regulator), which is a protein. Mutations in the AIRE gene lead to a variety of autoimmune diseases affecting multiple organ systems.
It has long been known that infections (infectious diseases) can cause autoimmune diseases in susceptible people. Pathogens can damage the mechanisms of immunological tolerance in a variety of ways.
Occasionally, the immune cell that is already disabling the pathogen releases various co-stimulating compounds that activate T cells, including autoreactive T-cells, and thereby inhibit the process from modifying the immune system to prevent self-destruction.
Some pathogens have a similar or identical epitope (part the antigen recognized by the antibodies or antigen receptors = antibody recognition site) as the autoantigens. As a result, the immune response to the external pathogen is also directed against its own protein and creates an autoimmune reaction with consequent tissue destruction. Some streptococcal infections may cause an immune response against the kidney, joints, and above all, to the heart (rheumatic fever).
Viral infections can cause similar cross-reactions, for example, during multiple sclerosis and type 1 diabetes.
Some microorganisms or their products (endotoxins, such as LPS) may act as superantigens, i.e., upon activation of the immune system, may induce an antigen-independent immune response. In this process, a large number of immune cells are activated, including autoreactive T cells, which are not eliminated during clonal anergy. These autoreactive T cells induce autoimmunity. Such processes may play a role in causing rheumatoid arthritis and presumably in type 1 diabetes mellitus.
Certain events or environmental exposures may cause or make worse of some autoimmune diseases. Sunlight, pesticides, chemicals called solvents, organic mercury are linked to many autoimmune diseases.
A new study has raised the possibility that stress may cause autoimmune disease, such as lupus or rheumatoid arthritis because it found a higher incidence of autoimmune diseases among people who were previously diagnosed with stress-related disorders.
I have patients who heard about this research and are saying, “I knew it!” – said Robert H. Shmerling, MD Faculty Editor, Harvard Health Publishing
The role of gender
It plays a vital role in the development of autoimmune diseases. Most of them are more common in women, although there are exceptions. The female to male ratio of the more common diseases in Lupus, Sjögren’s syndrome and autoimmune thyroid diseases are 9: 1, while in rheumatoid arthritis and multiple sclerosis 3: 1.
Also, the co-occurrence of autoimmune diseases in women is more common. The reason for this gender preference is unknown, but in addition to genetic factors, sex hormones are also likely to play a role. Mild cellular exchange during pregnancy may also play a role in the gender gap between the fetus and the mother.
How many autoimmune diseases are known?
More than 80 diseases occur as a result of the immune system attacking the body’s own organs, tissues, and cells. Some of the more common autoimmune diseases include type 1 diabetes, rheumatoid arthritis, systemic lupus erythematosus, and inflammatory bowel disease.
Autoimmune diseases list
- Type 1 Diabetes Mellitus – An autoimmune reaction against pancreatic beta cells that kill insulin-producing beta cells.
- Acute disseminated encephalomyelitis (ADEM) – encephalitis after viral infection or vaccination, caused by an autoimmune reaction.
- Addison’s disease – often caused by autoimmune death of the adrenal cortex.
- Anemia, “pernicious anemia” – a disease that causes a reduction in the number of red blood cells. After discovering that the disease is essentially due to vitamin B12 deficiency or absorption disorder, the disease can no longer be said to be “dangerous.”
- Antiphospholipid syndrome (APS) produces antiphospholipid antibodies that can cause arterial and venous thrombosis, as well as abortion and premature birth.
- Aplastic anemia often occurs as a result of an autoimmune reaction against bone marrow.
- Giant cell arteritis – a vascular inflammation that most often attacks the large and medium arteries of the head. It can cause loss of vision without treatment.
- Autoimmune hemolytic anemia – occurs when the immunoglobulin attacks the red blood cells.
- Autoimmune hepatitis – the immune system attacks the liver.
- Celiac disease – a chronic inflammation of the small intestine caused by cereal protein gluten in food.
- Goodpasture Syndrome – a rare illness characterized by lung hemorrhage and ever-worsening kidney failure. The autoimmune reaction is directed against an autoantigen found in both organs.
- Graves Disease – autoimmune hypothyroidism, the most common cause of hyperthyroidism, is characterized by the production of antibodies to TSH receptors on thyroid cells, with consequent overactive thyroid hormone.
- Guillain-Barré Syndrome (GBS) – an immune-mediated disorder of the surrounding nervous system that causes damage to peripheral neurons.
- Hashimoto’s disease – An autoimmune hypothyroidism, one of the most common causes of hypothyroidism. The immune system produces antibodies against specific proteins in the thyroid cells. Chronic inflammation develops, causing the thyroid to die over time.
- Thrombocytopenia – During the immune thrombocytopenic purpura (ITP), the immune system produces antibodies against platelets. The number of platelets decreases.
- Crohn disease – affecting the entire gastrointestinal tract, especially the small and large intestines, with inflammation of the digestive tract, causing abdominal pain, and diarrhea.
- Multiple Sclerosis – Immune-mediated demyelinating disease of the central nervous system, leading to a decrease in neuronal function.
- Myasthenia gravis – an antibody produced against the acetylcholine receptors of the motor endplate. Symptoms: fluctuating muscle weakness, exhaustion.
- Optic Neuritis – inflammation of the optic nerve that can cause partial or complete loss of vision.
- Opsoclonus Myoclonus Syndrome (OMS) – a neurological disease caused by an autoimmune attack on the nervous system. Symptoms include uncontrolled eye movement, involuntary twitching of a muscle, ataxia, intentive tremor, dysphasia, difficulty speaking, hypotonia, lethargy, irritability. About half of the cases are related to neuroblastoma.
- Pemphigus – a rare, chronic skin disease.
- Primary Biliary Cirrhosis (PBC) attacks the small bile ducts in the liver.
- Reactive Arthritis develops following bacterial enteritis or urethritis. It is associated with conjunctivitis, urethritis, inflammation of the skin, and mucous membranes.
- Rheumatoid arthritis – is the inflammation of the joints.
- Sjögren’s syndrome (sicca syndrome) – a chronic illness characterized by inflammation of the exocrine glands (especially saliva and tear glands). As a result of this process, the eyes, mucous membranes, and skin gradually dry out.
- Bechterew’s disease is a chronic, painful, progressive arthritis that causes inflammation of the vertebrae.
- Lupus or Systemic Lupus Erythematosus (SLE) It has many forms of appearance. Most often occurs in young women with symptoms of non-deforming arthritis, fever, low white blood cell count, skin symptoms, blood, or protein in the urine.
- Takayasu’s arteritis is a giant cell vascular inflammation that causes the aorta and its main branches to narrow. Symptoms: dizziness, syncope, visual disturbances, missing pulse, blood pressure difference on the limbs.
- Vitiligo – Spontaneously appearing white spots on the skin. There are no melanocytes in the pigment deficient area. Anti-melanocyte antibodies cause the disease.
- Wegener Granulomatosis – Vascular inflammation that attacks the lungs, kidneys, and other organs.
- Lichen ruber planus – Chronic inflammatory disease that affects the skin, nails, hair, and mucous membranes.
Note that: a person may have more than one autoimmune disorder at the same time
List of autoimmune diseases categorized by the organ
- “Molecular Mimicry.” Molecular Mimicry – an overview | ScienceDirect Topics. Accessed November 21, 2019. https://www.sciencedirect.com/topics/medicine-and-dentistry/molecular-mimicry.
- “Autoimmune Diseases,” n.d. https://www.niaid.nih.gov/diseases-conditions/autoimmune-diseases.