E-Cigarette Residue Exposure in Utero Shows Lasting Effects on Immune Response

Results from a new animal study found that maternal exposure to e-cigarette residues, with or without nicotine, affected offspring's immune response later in life. The study findings are published in the American Journal of Physiology-Lung Cellular and Molecular Physiology. The study has been chosen as an APSselect for November.

When e-cigarettes are used inside a building or vehicle, the vapor condenses on surfaces forming a thick oily layer. Despite growing evidence that direct and second-hand e-cigarette exposure is harmful, less is known about the potential effects of exposure to these vaping residues—known as third-hand exposure.

To find out how maternal third-hand e-cigarette exposure might affect a developing fetus, researchers conducted an experiment examining how this exposure in pregnant mice affects immune response and susceptibility to infections in their offspring later in life.

The researchers mimicked third-hand exposure by using low or high-power e-cigarette settings to deposit e-vapor residues with and without nicotine on to towels, which were changed daily. Mice were exposed to these towels or towels with no e-cigarette residue before, during and after pregnancy.

Once the offspring grew to adulthood, the researchers assessed various markers of immune system functioning. Some of the male adult offspring were also infected with mouse-adapted influenza A virus, and lung and bone marrow immune cell responses were assessed seven days after infection.

The researchers found that maternal third-hand exposure to low- or high-power e-vapor in the presence or absence of nicotine was associated with changes in both the innate and adaptive immune cell responses in offspring. Innate immune cells provide immediate, non-specific defense against pathogens while adaptive immune cells like B and T cells develop a specific and lasting response to specific pathogens.

The flu-infected offspring from the nicotine-exposed groups showed fewer lung alveolar macrophages, cells that play a critical role in the immune response to respiratory infections. These offspring also had more pronounced increases in neutrophils in the bone marrow, which could potentially hinder recovery from infections. Importantly, the e-vapor exposure led to lower activation of the CD4+ T cells and CD8+ T cells in the lungs of the flu-infected offspring, which could potentially compromise the ability to mount an effective immune response.

The researchers said that the study “shows that maternal third-hand exposure to e-vapor, irrespective of the presence of nicotine, exerts long-lasting, potentially detrimental, effects on the immune response of offspring in later life.”