Mice exposed to nicotine during pregnancy and in their first days of life showed a stronger inflammatory response to influenza later in life, according to new research. The changes to their blood-forming stem cells and immune systems persisted into adulthood, even though exposure had stopped shortly after birth.
How the study was carried out
The research team, led by the University of California, Santa Cruz, exposed pregnant mice to nicotine to study the effects of perinatal exposure on the blood-forming system. The findings were published in the scientific journal Stem Cell Reports.
Effects on blood-forming stem cells
The offspring exposed to nicotine had fewer blood-forming stem cells, which give rise to the mature immune cells that respond to threats.
The researchers also identified changes within these cells in the gene-expression patterns that regulate the immune system.
Effects largely invisible under normal conditions
Under normal conditions, the effects on the immune system were largely invisible. Mice exposed to nicotine had a normal number of immune cells circulating in their blood.
However, their lungs contained fewer macrophages, immune cells that form one of the body’s first lines of defence against pathogens.
Response to influenza infection
After infection with influenza, the immune systems of the exposed mice responded with more intense inflammation and increased movement of immune cells into the lungs.
This excessive response was associated with more severe damage to lung tissue and greater loss of body weight.
Limits of the findings
The researchers note that findings from studies in mice cannot necessarily be applied directly to humans.
The study nevertheless raises questions about nicotine exposure during pregnancy and the earliest stages of life, including exposure through products such as e-cigarettes and nicotine-replacement therapies.
Source: CNA
