Staphylococcus aureus Bacteria (artificially colored) were injected into mice to cause a serious condition called sepsis.Credit: Science Source/SPL
Genes that protect the body from infection during youth can be harmful in old age, a study shows1 In mice. The findings suggest that aging reduces immunity in unexpected ways, and not just by weakening the immune response.
The presence of a specific heart gene helped mice survive malignant infections, but only if the mice were young, the study authors reported. As for elderly mice, this gene led to an increased risk of death.
“In one case, this drug is protective,” says Andrew Wang, an immunologist at Yale University in New Haven, Connecticut, who was not involved in the research. “In another case, it actually leads to death.” The study shows that “the mechanisms that protect organs can vary greatly.”
These findings were published on how age affects the body’s ability to withstand invasion from pathogens nature The discovery, which will be made on January 14, could be a step toward developing treatments for diseases characterized by widespread immune dysfunction that wreaks havoc on the body, researchers say.
Withstand attack and defense
Surviving an infection requires your immune system to fight off harmful invaders. But it also requires the body to avoid damage from pathogens and overactive immune cells.
Young people often endure infections and immune defenses that their bodies launch to kill infectious organisms. “But as you get older, your ability to do this diminishes,” says Manu Shankar Hari, an immunologist at the University of Edinburgh in the United Kingdom.
Aging is associated with inflammation, but only in the industrialized world
To understand why this tolerance declines over the animal’s life, Janelle Ayres — co-author of the mouse study and an immunologist at the Salk Institute for Biological Studies in San Diego, California — and her colleagues studied a life-threatening condition called sepsis, which occurs when the immune system overreacts to an infection. The resulting immune storm causes organ damage and sometimes death. There are no targeted treatments beyond general antibiotics.
The researchers injected mice with large doses of bacteria, which led to sepsis in many of the animals. One group included young mice (equivalent to 20-30 years of age in humans); The mice in the other group were older (equivalent to 56-69 years in humans).