Diabetes, arthritis and multiple sclerosis trace back to the Black Death

Hamilton, Ontario – Diabetes, arthritis and multiple sclerosis can all trace their origins back to the Black Death, according to new research. McMaster University researchers say the bubonic plague that ravaged medieval Europe fueled the genes that make people vulnerable to autoimmune diseases today.

The Black Death has shaped human evolution by affecting responses to pathogens, and pandemics may continue to do so in the future, scientists warn. Natural selection has sped up among survivors, increasing the risk to their offspring, their research shows.

“When an epidemic of this nature – killing 30 to 50 percent of the population – is bound to select for protective alleles in humans, which means that those susceptible to circulating pathogens will die. Even a small advantage can mean the difference between survival or passing. Of course, Those who survive will pass on their genes to reproductive age,” explains evolutionary geneticist Hendrik Poiner, director of McMaster’s Ancient DNA Center. University liberation.

How did the plague lead the body to attack itself?

The findings are based on 516 ancient DNA samples obtained from the teeth of people who died before, during or shortly after the outbreak in the United Kingdom and Denmark. A century-long “window” enabled the international team to identify genetic differences that indicate who survived the virus.

Some of the remains were in a mass grave at East Smithfield outside London. Historical records and radiocarbon dating reveal that they all died between 1348 and 1349. The analysis showed that those who The protective variant is known as ERAP2 About 40 to 50 percent were more likely to survive.

“Selective advantages associated with selected loci have been reported to be the strongest in humans, showing how a single pathogen can have such a strong effect on the evolution of the immune system,” said human geneticist Luis Barreiro, a professor of genetic medicine. University of Chicago.

Over time, our immune systems have evolved to respond to pathogens in different ways. It’s a delicate balancing act. Some variants increase the risk of autoimmune diseases such as rheumatoid arthritis and Crohn’s disease. This may not have mattered during the Black Death, as the urgency made the cessation of trade inevitable. Thus, what was once a protective gene against plague in the Middle Ages may today increase susceptibility to the disease.

Autoimmune disease Occurs when the body’s natural defense system cannot tell the difference between your own healthy cells and foreign bodies. The body mistakenly attacks itself. There are more than 80 types that affect different organs.

The Black Death was the deadliest epidemic recorded in history

Bubonic plague killed up to 200 million Between 1346 and 1353. It was caused by bacteria Yersinia pestis Carried by flies and spread across Europe, the Middle East and North Africa — killing half the population.

The results suggest little to no prior immunological adaptation of the bug. Later on Bubonic plague outbreak Over the next 400 years, the death rate decreased. This may be the result of changing cultural practices, pathogen evolution or human genetic resistance.

Researchers found evidence of positive selection of mutations in immune-related genes during and after the Black Death. When comparing pre- and post-Black Death samples from London they identified 245 variants that were “highly divergent” – four of which were replicated in the Danish sample group.

Individuals who carried some or all likely had immune defenses that responded efficiently to Y. pestis, and as a result, were much more likely to survive infection. The study authors added that the variants are associated with protection from Y. pestis and overlap with mutations associated with increased susceptibility to autoimmune disease.

The findings highlight how past epidemics may have played a role Current disease risk. The Black Death remains the single greatest human death toll in recorded history, wiping out communities in some densely populated areas.

Those with two identical copies of ERAP2 survived the epidemic at a much higher rate than their counterparts in the opposite set. They neutralize Y. pestis by immune cells. Europeans living at that time were initially very vulnerable because they had no recent exposure to Yersinia pestis. Death rates declined as waves of epidemics recurred over the following centuries.

“Key to understanding the dynamics that have shaped the human immune system is how past epidemics like the plague contribute to our susceptibility to disease in modern times”.

The research is published in the journal the natureResults of seven years of work that took an unprecedented look at the immune genes of Black Death victims.

Southwest News Service writer Mark Waghorn contributed to this report.