Posted on Oct 07, 2019, 7 p.m.
Maternal exposure to common forms of industrial pollution has been shown to harm the immune system of offspring, and this can be passed onto subsequent generations to weaken the body’s defenses against infections, including the influenza virus.
"The old adage 'you are what you eat' is a touchstone for many aspects of human health," said Paige Lawrench, Ph.D with URMC Department of Environmental Medicine. "But in terms of the body's ability to fight off infections, this study suggests that, to a certain extent, you may also be what your great-grandmother ate."
Environmental pollution exposure has been shown to affect the reproductive, respiratory, and nervous system function across multiple generations, this new study published in the Cell Press journal iScience reveals for the first time that the immune system is also impacted.
Immune system multigenerational weakening may explain variations observed during seasonal and pandemic flu outbreaks such as annual flu vaccines providing some people protection, and during an outbreak some will get severely ill while others are able to fight off infections. Virus mutations, age, and other factors may explain some of this variation, but this doesn’t account for the diversity of responses to the flu infection.
"When you are infected or receive a flu vaccine, the immune system ramps up production of specific kinds of white blood cells in response," said Lawrence. "The larger the response, the larger the army of white blood cells, enhancing the ability of the body to successfully fight off an infection. Having a smaller size army -- which we see across multiple generations of mice in this study -- means that you're at risk for not fighting the infection as effectively."
Pregnant mice were exposed to environmentally relevant levels of PCBs which is a common byproduct of industrial production, waste incineration, and is found in some products; such chemicals manage to find their way into the food system to be eventually consumed by humans, these PCBs and dioxins bioaccumulate as they move up the food chain, as such they can be found in greater levels in animal based food products.
Production and function of cytotoxic T-cells was observed to be impaired when the animals were infected with influenza A virus; weakened immune response was observed in the offspring of dioxin exposed mothers and in subsequent generations as far as the equivalent of great grandchildren, and it was found to be more pronounced in female mice.
Exposure to dioxin binds AHR cells, the team hypothesized this to alter transcription of genetic instructions in some manner; exposure itself doesn’t trigger genetic mutations rather the cellular machinery by which genes are expressed is altered, and the phenomenon is then passed onto subsequent generations.
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