The mystery of what causes the fatal autoimmune disease Systemic Lupus Erythematosis has been solved by the identification of a possible genetic link.
Researchers at the University of California, San Diego School of Medicine (UCSD) uncovered the possible genetic link to SLE. Their report in a nationa journal say that a gene has been identified in mice which, if absent, causes symptoms remarkably similar to human SLE.
SLE is an incurable and potentially fatal multi-organ disease that turns victims' immune systems against them. The disease affects about one in 300 people, 90 per cent of them being women.It causes damage to kidneys, liver, brain, heart, spleen, joints, and lungs.
The investigators from UCSD,found that mice with a genetic mutation in an enzyme called alpha-mannosidase II develop lupus-type symptoms. This enzyme helps to form cell-surface carbohydrate structures called N-glycans, which enable the immune system to distinguish self from non-self.
In people with lupus and other autoimmune diseases such as arthritis, the body's white blood cells, instead of destroying invading bacteria and viruses, attack normal organs. While these cells appear normal in lupus sufferers, the victims' tissues and organs still appear ravaged by an attacking immune system.
Researchers had previously noticed that changes in N-glycans could lead to autoimmune disease. After pinpointing a gene which produces an enzyme that starts the glycan formation pathway, researchers bred mice without this gene. They found the gene-deficient mice had much lower levels of N-glycans, and abnormally shaped N-glycans molecules. At the same time, these mice had high levels of antibodies, kidney inflammation and other tissue damage.
Senior author of the study, Professor Jamey Marth said: "this is an entirely new manner by which autoimmune disease can occur, by a gene controlling carbohydrate formation. These findings provide new insights into understanding autoimmune disease and suggest new diagnostic tests for possible causes of human SLE ".