Stem Cell Reports: Nicotine Exposure During Pregnancy Permanently Weakens Offspring’s Immune Systems

A research team led by Camilla Forsberg of the University of California, Santa Cruz, in the United States exposed pregnant mice to nicotine to investigate the effects of perinatal exposure on the blood-forming system. Their offspring had fewer hematopoietic stem cells — the cells that produce mature immune cells — as well as altered patterns of immune-regulatory gene activity in these cells. The changes persisted into adulthood, even though nicotine exposure had stopped shortly after birth.

The immune impairment was almost undetectable under normal conditions: adult mice had normal numbers of immune cells in their blood. However, their lungs contained fewer resident macrophages, immune cells that provide the first line of defense against pathogens. When mice exposed to nicotine during the perinatal period were later infected with influenza, their immune systems responded with increased inflammation and a greater influx of immune cells into the lungs. This resulted in more severe lung damage and greater weight loss.

“This shows how sensitive the developing blood-forming system is to its environment. Blood stem cells establish the balance of the immune system and retain a memory of what they encounter early in life. Exposure during the first weeks of life can shift this balance in ways that remain hidden until the body encounters an infection, ultimately influencing immune health in adulthood,” explained Dr. Marcel Rommel.

Smoking during pregnancy is known to negatively affect fetal development, including the development of the immune system. Children born to mothers who smoke are more likely to experience respiratory infections, which can also be more severe.

However, tobacco smoke contains many harmful substances besides nicotine, making it difficult to assess the effects of nicotine alone. The study helps address this question by isolating nicotine exposure in a mouse model. “What happens during early development can determine health throughout life. Our findings show how perinatal nicotine exposure can irreversibly alter the stem cells responsible for building the immune system,” noted Dr. Taylor Kuhl.

Although findings from mice cannot necessarily be directly extrapolated to humans, the study raises important questions about nicotine exposure during pregnancy and early development, including exposure through e-cigarettes and nicotine replacement therapy.