Study association between infections and autoimmune diseases has been demonstrated

Researchers are deciphering the link between autoimmunity and infection
So far, the various forms of autoimmune diseases are poorly explained and in the end, the question remains why the immune system is directed in some people against their own body cells. Scientists at the University of Basel have now discovered a possible connection between the occurrence of autoimmune diseases and previous infections, which provides a new explanatory approach.

Previous studies have already shown that autoimmune reactions may be related to infection, but the underlying mechanism has remained unclear. The scientists of the University of Basel have now discovered a possible explanation here. "If the defense cells pick up certain proteins from the pathogen cells, errors can occur," the researchers report. This sometimes causes the phenomenon of autoimmunity after infection. The scientists published their study results in the "Proceedings of the National Academy of Sciences" (PNAS).

T lymphocytes can become active against different other cells. A defective protein uptake of the B lymphocytes leads here to an activation of the T lymphocytes against the body's own cells. (Image: Juan Gärtner / fotolia.com)

New explanation for autoimmunity
Autoimmunity, the inability of an organism to recognize its parts as endogenous, can cause serious health problems. The causes of the symptoms are still largely unclear. Although in addition to the connection with infections and a connection with the excessive everyday hygiene is given as given, but the underlying mechanisms remained unclear. Together with scientists from the Whitehead Institute in Cambridge (USA), the researchers around Professor Tobias Derfuss from the University of Basel have now pursued a new hypothesis.

Error in protein intake
Based on the special ability of the immune cells to recognize certain proteins on the surface of neighboring cells and to take them out of the cell membrane, the researchers came to the assumption that errors could occur as well. If proteins of the body's own cell membrane are taken in, this is a possible explanation for the subsequently occurring autoimmunity.

B lymphocytes absorb different proteins
In their research, the researchers found that special immune cells, called B lymphocytes, not only receive the protein of a flu virus they specialize in, but also small amounts of other neighboring membrane proteins. For example, a protein known as autoantigen from the cell membrane layer in the central nervous system. In the animal model, the immune response to this membrane protein led to autoimmune inflammation in the brain, the researchers report. In humans, it could probably also contribute to such an inflammation.

Activation of autoaggressive T lymphocytes
According to the researchers, B lymphocytes cultured with cells that had integrated both the influenza virus protein and the membrane protein not only activated other immune cells (certain T lymphocytes) against the virus, but also t-lymphocytes activates the body's own membrane protein. "Thus, a virus infection via an error in the protein uptake of B lymphocytes could lead to an activation of autoaggressive T lymphocytes," reports the University of Basel. This could trigger an autoimmune inflammation of the brain. The researchers thus provide a new explanation for the occurrence of autoimmunity. (Fp)