The defense system that usually protects patients from external aggression turns on its own cells ; and attacks them for reasons that are not know. Scientists from the Institut Pasteur have shown that ancient viruses are involve ; therefore in the acute inflammatory defense response that may contribute to the disease. Autoimmune diseases result from a dysfunction of the immune system. The immune system protects you from disease and infection.
Immune system protects
Autoimmune diseases can affect any part of the body. More than 80 autoimmune diseases are identify. Some are relatively well know, such as type 1 diabetes, multiple sclerosis, lupus, and rheumatoid arthritis, while others are rare and difficult to diagnose. The causes of autoimmune diseases remain largely unknown.
Sometimes, though, the immune system can produce auto antibodies that attack healthy cells, tissues, and organs. This can lead to autoimmune disease. Multiple sclerosis (MS) is an incurable inflammatory autoimmune disease that leads to irreversible damage to the brain and spinal cord. This disease is also associate with the reactivation of ancient viruses, which were insert in our DNA during the evolution of humankind.
Attack healthy cells
It was therefore long thought that multiple sclerosis was due to a viral infection. Multiple sclerosis (MS) is an autoimmune disease. “Our study shows that reactivation of ancient viruses does not correspond to an infectious phenomenon, but to a defense response of the body when faced with an acute inflammatory phenomenon” explains Christian Muchardt, Head of the Epigenetic Regulation Unit at the Institut Pasteur.
Viral sequences were neutralized during evolution and no longer represent a source of infection. But these sequences are a source of external DNA containing information about virus behavior. Cells have therefore been able to control these sequences to detect infections as quickly as possible and turn on their defense genes during an attack.
Neutralized during evolution
These viral sequences are, above all, used to control defense genes in stem cells. They lie dormant in adult cells and it is the more traditional sequences that become active. By examining samples from patients with MS, the scientists observe that regulatory sequences of viral origin emerge from their dormant state and were responsible for abnormal expression of several pro-inflammatory genes.
To conclude, in multiple sclerosis, activation of viral sequences does not correspond to an infectious phenomenon but to the unexpected use of regulatory sequences, leading to chronic excessive inflammation. “The discovery of this mechanism, linked to epigenetic phenomena, may one day pave the way for management of MS using small molecules that inhibit chromatin modification enzymes” sums up Christian Muchardt.