Pre-birth bacteria exposure may prevent allergies
Wednesday December 9th, 2009
It's been thought for a long time that child-hood exposure to bacteria reduces the risk of asthma and allergy - but new findings suggest this begins in the womb.
The bacteria that pregnant women encounter may affect their child's risk of allergies, according to a new study.
Exposure to bacteria during pregnancy could trigger a reaction which protects the unborn child, say Dr Melanie Conrad and her team at Philipps-University of Marburg in Germany.
It is widely thought that young children's exposure to bacteria may cause their immune system to tolerate allergens later in life. But the researchers believe this process may begin during pregnancy.
They exposed pregnant mice to bacteria from a barn-yard. Their babies were born resistant to asthma symptoms like allergies of the airways.
This was probably due to the bacteria causing mild inflammation, increasing proteins called "Toll-like receptors", and dampening down the immune system.
The experts aren't sure how Toll-like receptors are linked to allergy resistance in offspring, only that they "play a pivotal role". They also don't know whether the protection applies to a broad range of allergens, including foods.
Details are published in the Journal of Experimental Medicine.
Dr Conrad writes that the experiment shows a "direct relationship" between bacterial exposure during pregnancy and asthma protection in the child. It could lead to better ways of preventing asthma, she hopes.
Child health expert Dr Patrick Holt of the University of Western Australia, says there is now good evidence that allergy protection can "occur in the developing foetus as a result of microbial stimulation of the pregnant mother".
He also predicts that this mechanism, if confirmed, could apply to many other diseases.
Conrad, M. L. et al. Maternal TLR signaling is required for prenatal asthma protection by the nonpathogenic microbe Acinetobacter lwoffii F78. The Journal of Experimental Medicine, published online December 7, 2008.
Holt, P. G. and Strickland, D. H. Soothing signals: transplacental transmission of resistance to asthma and allergy. The Journal of Experimental Medicine, published online December 7, 2008.
Tags: Allergies & Asthma | Child Health | Childbirth and Pregnancy | Europe | Women’s Health & Gynaecology
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