It is well recognized that mothers who smoke during pregnancy increase the risk of their babies being born premature and of low birth weight. More recent research has found that exposing the fetus to tobacco smoke also increases the risk of pediatric and adult obesity, but the mechanisms responsible for it are not really understood.
Studies by a team led by the University of Kentucky now suggest that maternal smoking increases the levels of a protein called chemerin – which is linked to obesity in adults – in their newborns. The results, reported by Kevin Pearson, Ph.D., and colleagues in Experimental Physiology, suggest that smoking during pregnancy can affect the epigenetic control of chemerin in the fetus and newborn, which increases the risk of obesity later in life. Describing the studies in an article entitled "Smoking During Pregnancy Boosts Expression of Chemerin in Neonatal Tissue," the researchers concluded, "Our data provide a potentially new mechanism behind the increased risk of obesity in babies born to mothers who smoke during the pregnancy. "
In the United Kingdom, 26% of adults and 20% of children are obese, costing society around 27 billion pounds a year, according to data from the UK government cited by the Physiological Society. Obesity rates also continue to rise, suggesting that other environmental factors, in addition to diet and genetics, may be contributing. In the US, nearly 35 percent of adults and 20 percent of children ages 6 to 19 are obese, costing the US health care system about $ 200 billion a year, the authors added. "Although several factors play a role in the development of obesity and metabolic disorders, a potential contribution is not utero environment during pregnancy. "
Chemerin is an adipokine that regulates adipose cell differentiation. Chemokine levels are elevated in obese and exposed people, but if chemerin levels are altered in neonates exposed to cigarette smoke not utero was not investigated, the authors wrote. They examined the expression of the chemerin gene discarded prepuce samples of circumcised babies of mothers who smoked during pregnancy compared to newborns of nonsmokers. The foreskin is simple to collect, and the team has previously shown that it has tissue-like properties, such as fat, that it would not be possible to collect from newborns.
Tissue analyzes showed that chemerin expression was significantly higher in the prepuce tissues of infants who were exposed to cigarette smoke not utero, compared to controls. "Cells collected from babies born to smokers demonstrated high expression of chemerin mRNA compared to cells isolated from babies born to nonsmokers," the researchers wrote. Chemerin levels were also increased in primary dermal fibroblasts derived from tobacco, which were cultured and stimulated with an adipogenic cocktail.
Interestingly, subsequent analyzes showed that chemerin DNA methylation was lower in all newborn tissues of smoking mothers, suggesting that epigenetic mechanisms may be involved in smoke-induced changes in chemerin gene expression. "Current data support a potential mechanism by which exposed children or adults not utero cigarette smoke may show higher rates of obesity later in life, "the team concluded. "Others have shown that although exposed newborns not utero for cigarette smoke tend to be smaller, they have higher rates of obesity later in life, suggesting altered development schedule … "
The team acknowledged that their study has limitations, even because the results can not be extrapolated to the female offspring. In addition, the researchers write, "… we are doing these measurements on epidermal / dermal samples and predict that adipose tissue would respond in a similar way, which may not be the case. Due to limited tissue availability, we could only assess DNA methylation and mRNA expression of chemerin instead of protein expression in our samples, so this should be investigated in the future. "However, they commented:" Despite the limitations present, these findings important new evidence for a link between maternal smoking during pregnancy and increased expression of mRNA of chemerin. "
The team aims to assess the effects of other maternal behaviors on the health of offspring. "Our long-term plan is to study the impact of exercise during pregnancy and its ability to improve health outcomes in children," said Dr. Pearson. "However, as we began to transition our work from laboratory animals to humans, it quickly became apparent that a rather high percentage of the pregnant population at our hospital continued to smoke cigarettes during pregnancy. Thus, we set out to investigate the mechanisms by which babies born to smokers are at risk for subsequent diseases. In the future, we would like to work on ways to improve smoking cessation programs or ways to increase exercise levels in smokers as a way to combat negative outcomes in offspring, but we are really starting to scratch the surface in that area.