Khaberni - Doctors have long noticed that children who grow up in environments rich in biodiversity, such as farms or homes with pets, are less likely to develop allergies compared to their peers in highly sterilized environments. However, the precise scientific reason has been unclear for decades.
Now, researchers from Yale University have discovered a biological explanation for this, after their study showed that early and varied exposure to microbes and natural proteins forms a "broad immune memory," which helps the immune system respond in a balanced manner rather than overreacting to harmless substances.
In the study published in the journal Nature, researchers compared two groups of mice, where one group was raised in a natural environment rich in microbes, resembling realistic conditions outside the lab, while the other was raised in a sterile environment inside laboratories.
When both groups were exposed to common allergens, such as proteins from peanuts, soy, and peas, the mice raised in the natural environment showed clear resistance to severe allergic reactions, compared to the "clean" mice, which exhibited stronger reactions.
The results demonstrated that early environmental exposure encourages the immune system to produce a type of antibody known as IgG, which is different from the IgE antibodies responsible for most cases of allergies in humans.
This shift in immune response reduces the likelihood of allergic reactions and makes the body more capable of handling allergens as non-hazardous elements.
The lead researcher in the study, Professor of Immunology at Yale University Russlan Medzhitov, stated that the immune system in natural environments "learns" how to balance protection and not to overreact, whereas the immune system in highly clean environments remains "untrained" and more prone to deviate towards allergies.
The price of "extreme cleanliness"
The study suggests that industrial advancement and widespread reliance on sterilization and antibiotics, despite their great benefits in fighting serious diseases, have contributed to reducing human exposure to beneficial microbes, leaving the immune system in an unprepared state.
Researchers believe that this imbalance might explain the noticeable increase in rates of allergies and autoimmune diseases in modern societies, affirming that environmental factors are just as important as genetic factors in this context.
The significance of these findings extends not just to prevention but also opens the door to developing new therapeutic strategies for allergies, based on enhancing protective immune responses instead of merely suppressing symptoms. It may also contribute to reevaluating modern lifestyles, especially during the early years of a child's life.
The researchers conclude that deliberate and natural exposure to the environment might be an essential element in building a healthy immune system, scientifically reminding us that "a little dirt" can sometimes be more beneficial than we might think.
