Autoimmune disease can be a side effect of a strong immune system.
Evolution can be blamed for our autoimmune diseases such as lupus, multiple sclerosis and rheumatoid arthritis. For the first time, we have evidence that people who are more susceptible to these types of disorders are in this way because their immune systems are better equipped to fight dangerous infections, allowing them to live longer. Can live
“There are a lot of autoimmune diseases that affect all types of tissues,” said evolutionary biologist Andrea Graham of Princeton University at the annual meeting of the International Society for Evolution, Medicine, and Public Health in Durham, North Carolina. , last month. So what can explain the existence of these conditions? “One possible answer is that vulnerability to immune-mediated disease is just the price we should pay for a powerful and rapid rescue for infection.”
Graham and colleagues have found evidence for this idea using long-term studies of older people in Taiwan. It has tracked over 1000 people born between 1892 and 1953 during the last 27 years.
The team analyzed blood samples collected from 639 of these people in 2000 and 2006, measuring levels of “self-reactive” antibodies capable of attacking the body’s own tissues. They found that people with high levels of these antibodies were likely to live longer.
For a particular age, participants with a high level of self-reactive antibodies had an average 33% lower risk of dying that year. These people also seemed less likely to have a type of chronic viral infection.
Its disadvantage is that these antibodies are involved in autoimmune diseases. The kidney affected by autoimmune lupus disorder is one of the first organs, so the team also analyzed urine samples, which could impair kidney health. They found that people who had higher levels of autoreactive antibodies may also have the potential to develop lupus.
What makes this study remarkable is that it explains in evolutionary terms why human development has failed to eradicate autoimmune diseases, says evolutionist Gabriel Sorsi of the University of Bogerogne in France.
The work was inspired by Graham’s findings from a similar study in the United Kingdom that includes humans but not sheep. For the past 30 years, researchers have been recording the health and life details of more than 7,000 flocks on the Scottish island of St Kilda.
When analyzing antibodies in sheep blood samples, Graham’s team found that there was an association between self-reactive antibody levels and parasitic antibody levels, and that a higher level of self-reactive antibodies was found in sheep families goes. Together, the findings suggest that genetics affect autoreactive antibody levels, and this is related to a stronger defense against parasites. This provides an evolutionary advantage: sheep with high levels of self-reactive antibodies live longer.
Aaron Autowell, an evolutionary anthropologist at the University of California at Santa Barbara, says “autoimmunity was previously thought to be the worst thing and immune system failure to attack rather than what it should do.” “These studies suggest that there may be a function for autoimmunity,” Blackwell says.
Statistical analysis of sheep data showed that the association between living and high-level autoactive antibodies is not superior to defeating parasites. This may mean that autoreactive antibodies are not just a side effect of a strong immune system, they can also do something useful. Other studies suggest that autoreactive antibodies may help remove dying cells and other wastes from the body, and it is possible that they may play a role in the observation of cancer cells.
The emerging picture is that physiological responses are the product of long evolutionary processes, and often complete a task that makes an animal more likely to survive under the right conditions, Blackwell says. “I hope that these results apply in many species and in various human populations,” he says.