“When I began, autoimmune disease was a field that was nonexistent. People thought it was a crazy idea.”

— Noel R. Rose “Father of Autoimmunity”

Autoimmunity begins when, instead of targeting foreign pathogens, the immune system starts targeting its own body. Models to study autoimmunity can be either induced or spontaneous. Spontaneous models and human diseases arise from events that are currently incompletely known to us. Some infectious agents have proteins that “look” like self-proteins, so when the immune system attacks the infection they remember that it “looks” like self…. so then the immune system starts attacking the self-proteins and damaging the body.

Organ specific diseases: Hashimoto’s thyroiditis and Grave’s diseases (attack on thyroid); type 1 diabetes (attack on pancreatic beta cells). Hashimoto’s thyroiditis results from antibodies against thyroid peroxidase, Grave’s results from antibodies against thyroid-stimulating hormone receptor, type 1 diabetes results from antibodies against insulin

Systemic diseases: Systemic Lupus Erythematosus (SLE) and primary Sjogren’s syndrom (many tissues attacked – skin, brain, kideneys….). SLE results from antibodies against common cellular components (dsDNA, chromatin, sliceosome complex).

Some autoimmune diseases can be either-or, like hemolytic anemia which can be a stand-alone disease that destroys red blood cells or part of SLE.

Animals are actually “super-organisms”…

Is the microbiome an organ? Good question. If yes, then we could potentially classify Inflammatory Bowel Disease (IBD) as an autoimmune disease because it is caused by intolerance of the microbes living in the gut, which in turn affects the intestinal tissues causing inflammation. Personally, I like the idea that our identity is part bacteria, fungus, and virus. Animals are actually “super-organisms” composed of host cells and colonizing microbes.

Citations

Janeway’s Immunobiology, 9th edition, Kenneth Murphy and Casey Weaver