Naked Science Forum
Life Sciences => Physiology & Medicine => Topic started by: scientizscht on 07/04/2019 14:58:05
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Hello
I am interested in how the autoimmune diseases work, not how they start.
Any input?
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Autoimmunity is the inappropriate attack by elements of the immune system on the body's own tissues. Usually the target is a discrete tissue or cell type, although sometimes the ensuing inflammatory process also causes "bystander" damage to nearby otherwise unaffected tissues. SLE (lupus), which causes damage in tissues throughout the body ranging from joint problems to heart, muscle, brain, skin and eye conditions, is a good example of this.
As a family of disorders, autoimmune conditions tend to be more common in females than males, particularly post-partum, perhaps as a consequence of immune reprogramming during pregnancy, or microchimerism where foetal cells take up residence in maternal tissues (https://www.thenakedscientists.com/articles/science-features/microchimera-mixture). See also https://www.thenakedscientists.com/articles/science-news/foetal-dna-mum%E2%80%99s-brain
The trigger for an autoimmune condition can be genetic, as evidenced by a family history of allergic or inflammatory diseases like psoriasis and arthritis. Prior infection is also thought to be a trigger in some susceptible individuals. Type 1 diabetes mellitus, for example, has been linked to antecedent viral infections, perhaps with members of the coxsackie virus family. These agents are believed to provoke a state of immune cross-reactivity where the infection leads to the formation of immune elements targeted at the pathogen but which also have an affinity for markers carried by healthy tissue.
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Ok but how the immune system attacks the normal tissues?
Autoantibodies go and bind to normal tissues and then?
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how the immune system attacks the normal tissues?
In autoimmune diseases, the immune system uses the same mechanisms it uses against genuine invaders (eg bacteria and viruses) and false invaders (eg food allergies).
A good description of the immune system is given here, in the context of food allergies:
https://player.fm/series/the-after-on-podcast/episode-46-kari-nadeau-defeating-food-allergies
Also see: https://en.wikipedia.org/wiki/Autoimmune_disease
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Ok but how the immune system attacks the normal tissues?
Autoantibodies go and bind to normal tissues and then?
It depends upon the disease.
Some conditions arise through the production of abnormal clones of antibodies. A good example of this would be myasthenia gravis, where antibodies are produced against the acetyl choline receptor at the neuromuscular junction, causing problems with the transmission of nerve impulses into muscles to initiate movements.
Other autoimmune conditions are caused by T cells attacking the body's own tissues directly in the same way that they would wipe out a virally-infected cell. Examples of this include type 1 diabetes, rheumatoid arthritis and MS.
Often, both manifestations occur, so the tissue is damaged by a combination of autoreactive T cells and antibodies.
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Ordinarily, immune system produces antibodies (proteins that recognize and destroy specific substances) against harmful invaders-including: viruses, bacteria, parasites and fungi-in your body. When you have an autoimmune disease, your body produces antibodies against some of your own tissues. Diagnosing an autoimmune disease involves identifying the antibodies your body is producing.