It’s been more than five years since Stanford scientists discovered that 77% of the activities of the immune system are dominated by environment and lifestyle triggers, rather than genetics. Their ground-breaking research findings were published in the distinguished journal, Cell, and helped change the way we look at health and disease, particularly in immune-mediated conditions, like autoimmunity.
The role of genetics in human health is an area of intense study. And while it has been discovered that one’s DNA plays a role in the occurrence of disease, genetic make-up alone rarely explains why someone actually gets sick. In order to investigate this further, a team of researchers at Stanford University School of Medicine studied sets of twins to determine the similarities and differences in their immune function. They analyzed blood samples to measure over 200 immune system components and activities in 78 pairs of identical twins (who share 100% of their DNA) and 27 pairs of fraternal twins (who, like regular siblings, share, on average, 50% of their DNA).
The findings were striking. In more than three-quarters of the tests the researchers performed, they found that non-heritable influences – things like diet, previous infections, toxic exposures and lifestyle factors, like sleep and exercise – were responsible for the immune system’s composition and activities. In other words, in genetically identical twins, less than one-quarter of immune system behavior is similar in both siblings. Further supporting these results was the investigators’ discovery that this variability in immune system activity became more pronounced in older sets of twins, who would naturally have accumulated more diverse environmental influences as they aged.
These results have important implications for autoimmunity. In the effort to better understand, treat and prevent autoimmune diseases, the recognition that an individual’s environment has a big influence over how their immune system behaves opens the door for a whole new category of interventions – among these are interventions that address important lifestyle elements like diet, exercise, stress management and sleep. According to Dr. Fotios Koumpouras, Professor of Medicine and Director of the Lupus Program at Yale School of Medicine, "These exciting findings suggest that there may be an important role for modifying environmental and lifestyle factors to help treat diseases driven by immune system dysfunction - diseases like rheumatoid arthritis, lupus, psoriasis and dozens of other autoimmune conditions”.