New scientific research has demonstrated that exposure to dioxin, a common toxic chemical in industrial pollution, during pregnancy can harm the immune system of offspring and that this injury is passed along to subsequent generations, weakening the body’s defenses against infections such as the influenza virus. Exposure to dioxin in pregnancy occurs primarily in the food humans eat: These chemicals find their way into the food system where they are eventually consumed by humans. Dioxins and PCBs bio-accumulate as they move up the food chain and are found in greater concentrations in animal-based food products.
While other studies have shown that environmental exposure to pollutants can have effects on the reproductive, respiratory, and nervous system function across multiple generations, the new research shows for the first time that the immune system is impacted as well. This multi-generational weakening of the immune system could help explain variations that are observed during seasonal and pandemic flu episodes.
In the study, researchers exposed pregnant mice to environmentally relevant levels of a chemical called dioxin, which, like polychlorinated biphenyls (PCBs), is a common by-product of industrial production and waste incineration, and is also found in some consumer products. These chemicals find their way into the food system where they are eventually consumed by humans. Dioxins and PCBs bio-accumulate as they move up the food chain and are found in greater concentrations in animal-based food products.
The scientists observed the production and function of cytotoxic T cells — white blood cells that defend the body against foreign pathogens, such as viruses and bacteria, and seek out and destroy cells with mutations that could lead to cancer — was impaired when the mice were infected with influenza A virus. This weakened immune response was observed not only in the offspring of the mice whose mothers where exposed to dioxin, but in the subsequent generations, including as far out as the rodent equivalent of great-grandchildren. The researchers also found that this effect was more pronounced in female mice.
“The old adage ‘you are what you eat’ is a touchstone for many aspects of human health. But in terms of the body’s ability to fights off infections, this study suggests that, to a certain extent, you may also be what your great-grandmother ate.”
-Paige Lawrence, Ph.D., University of Rochester Medical Center’s (URMC) Department of Environmental Medicine
Journal Reference: Christina M. Post, Lisbeth A. Boule, Catherine G. Burke, Colleen T. O’Dell, Bethany Winans, B. Paige Lawrence. The Ancestral Environment Shapes Antiviral CD8 T cell Responses across Generations. iScience, 2019; 20: 168 DOI: 10.1016/j.isci.2019.09.014