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Childhood Asthma Risk Starts Before Birth

Kathleen Blanchard's picture

A finding from Cincinnati researchers shows that the risk of childhood asthma may start before birth. Children born to women who live in high traffic areas are now shown to develop gene "reprogramming" that starts in the womb, affecting normal lung development.

Children born in high traffic areas seem to have a greater risk of asthma because of gene altering exposure to polycyclic aromatic hydrocarbons (PAHs), byproducts of incomplete combustion from carbon-containing fuels. PAH's also linked to increased risk of cancer, heart disease, respiratory ailments, and other inflammatory related diseases.

The study findings are published in the Feb. 16, 2009, issue of PLoS ONE. The results may provide information for predicting environmentally induced asthma resulting from exposure to pollution during pregnancy.

The study contributes to a growing body of evidence that shows us the role of epigenetics (how our genes change expression) and disease. Epigenetic studies focus on how genes misbehave to cause illness. The current study explores how exposure to PAH from traffic alters gene programming in the womb, during fetal development, leading to airway inflammation and asthma in childhood.

Shuk-mei Ho, PhD, senior author of the paper says, "Our data support the concept that environmental exposures can interact with genes during key developmental periods to trigger disease onset later in life, and that tissues are being reprogrammed to become abnormal later." Dr. Ho is chair of University of Cincinnati's Department of Environmental Health and the director of the Center for Environmental Genetics where the study was conducted.

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The specific alteration involves the gene ACSL3. The researchers measured white blood cell counts from the umbilical cords of 56 children living in Northern Manhattan and the South Bronx. The expectant mothers wore pack back monitors to measure air quality and PAH exposure during pregnancy. The scientists looked for epigenetic gene alterations that occur in the womb that put children at risk for asthma before age five.

The study found a significant risk of asthma in childhood as the result of pollution exposure in the womb, during fetal development. Exposure to PAH leads to changes in ACSL3 methylation, a gene that is important for normal lung development.

Study co-author, Rachel Miller, MD, director of the Columbia Center for Children's Environmental Health (CCCEH) asthma project says, "Understanding early predictors of asthma is an important area of investigation, because they represent potential clinical targets for intervention."

The study is important to the public. Finding ways to intervene is crucial for any child suffering from asthma. A greater focus on disease prevention by targeting air quality could certainly decrease the risk of childhood asthma from maternal exposure to PAH, along with a variety of other diseases.

Pollution is linked to increased heart disease, respiratory disease, and other inflammatory processes in the body that promote human illness. The new study shows that the risk of asthma in children starts in the womb, during critical stages of fetal development. Maternal exposure to air pollution before birth is now linked to increased asthma risk in children before age five.

Source: UC.edu