Washington: A new study has demonstrated how exposure to tobacco smoke affects the development of human immune system on molecular level.
Dr. Gunda Herberth and Dr. Irina Lehmann from the UFZ investigated the relationship between smoking mothers during pregnancy on the one hand and their children's risk of developing allergies on the other, the scientists from Leipzig examined microRNA-223, microRNA-155 and regulatory T cells - not only in the blood samples of pregnant women (36 weeks pregnant) but also at birth in the cord blood of their babies.
At the same time, questionnaires were filled out and urine samples of the pregnant women were tested to substantiate the effect from exposure to tobacco smoke and/or from volatile organic compounds resulting from smoking.
From the pool of mothers participating in the LINA-study, 315 mothers (6.6 percent of whom were smokers) and 441 children were consulted in these investigations.
The focus was on miR-223 and miR-155, because their role in regulating T cells had already been proven.
By measuring the concentration of these microRNAs as well as the number of regulatory T cells in maternal and cord blood it could be shown that a high exposure to inhaled volatile organic compounds (VOCs) associated with tobacco smoke coincides with high values for miR-223.
At the same time it was also found that increased values for maternal and umbilical cord blood miR-223 correlate with low regulatory T-cell numbers.
Finally, it could be shown that low regulatory T-cell numbers in umbilical cord blood was an indication that children exposed to tobacco smoke were more likely to develop an allergy before the age of three compared to those children with normal values for miR-223 and Treg cells.
The study has been published in the Journal of Allergy and Clinical Immunology.