How Do Viruses Elicit Autoimmunity?

Viral impact in triggering autoimmunity has been discovered by a study at the Washington University School of Medicine in St. Louis, published in the Journal of Experimental Medicine.

Autoimmune diseases occur as a result of immune systems attacking their body cells. Apart from genetic factors that increase the susceptibility to autoimmunity, environmental triggers have also been proven more elusive.

‘Viral infection is found to set a destructive process that may culminate in autoimmunity even long after the infection has resolved.’

The study in mice investigated the impact of viral infection on T cells (a group of immune cells) that play a key role in many autoimmune conditions. The team state that the human roseoloviruses, close relatives of murine roseolovirus, warrant investigation as possible causes of autoimmunity in people.

"It is very hard to find the culprit of a crime that was never even at the scene of the crime. As clinicians, we often look directly in the diseased tissue, and if we find no virus we conclude that the disease was not caused by a virus. But here we have a situation in which a virus is doing its damage someplace else entirely. This virus goes to the thymus, which is where T cells undergo a process to select those cells useful for immune defense but also get rid of T cells that are too likely to damage the body's own tissues. And what we find is that this whole process, which is called central tolerance, is affected. T cells that shouldn't leave the thymus get out, and they manifest months later in the stomach, causing an autoimmune disease in a location that was never infected with the virus," says senior author Wayne M. Yokoyama, MD, the Sam J. Levin and Audrey Loew Levin professor of Arthritis Research.

The team also plans to further investigate other factors that make some people more susceptible to the autoimmune effects of the virus.

Source: Medindia