Under normal circumstances, the immune system is designed to defend the body against infectious diseases, while hosting its own healthy cells and related tissues. An AID occurs when the self-tolerance mechanisms become defective, allowing autoreactive lymphocytes to attack certain areas of the body. The immune system then becomes pathogenic, inducing tissue or cell damage. These diseases evolve chronically throughout life, with phases of relapses and remissions. Co-stimulatory signals are necessary to enable the harmful T-cell activation to continue.
There are currently more than 80 AID, the most common being rheumatoid arthritis, colitis, multiple sclerosis, psoriasis, diabetes mellitus type 1 and lupus erythematous. In western countries, AID are the primary cause of disability in young adults.
AID may be divided into two classes: organ or tissue-specific AID (for example, autoimmune thyroiditis, myasthenia, pemphygus, etc.) and non-organ specific AID, also called systemic diseases. AID are multifactorial (genetic, endocrine, environmental factors).
The occurrence of AID makes this group of diseases a major health issue, similar to cardiovascular disease or cancer. Autoimmune diseases are chronic, affect young patients and require long term treatments.
Each AID has its own specific treatment regimen with treatment indications strictly symptomatic, anti-inflammatory, immunosuppressive and/or substitutive. The most widely used therapies include corticoids, immunosuppressors and immunomodulators. The use of such chronic treatments is limited, however, due to treatment intolerance and frequent therapeutic escape.