Allergies can be a real annoyance for most people. However, what if the reason for an individual's allergy was their own mother? A new multi-institutional study by researchers from Singapore has found that mothers can pass on allergies to their offspring during development in the womb.
According to the study, an antibody known as immunoglobulin E (IgE), responsible for the triggering of allergic reactions, can enter the fetus from the mother's body through the placenta, and bind with immune cells responsible for triggering allergic reactions. This imbibed the fetus during their development with the predisposition for developing allergies in the future.
"Allergies begin very early in life. Infants experience allergic responses closely linked with the mother's allergic response in ways that cannot only be explained by genetics. This work emphasizes one way that allergic responses can pass from the mother to the developing fetus, and shows how allergies can then persist after birth," said Prof.Ashley St. John, a senior co-author of the study, in a statement.
Evidence of Allergy Inheritance
The transmission of diseases and other health conditions from mother to fetus is not unheard of. However, the transmission of allergies is a rather unexplored area. For the study, the authors utilized a mice model. Prior to their pregnancy, the mice were exposed to a common allergen, ragweed pollen.
The offspring born to these mothers also exhibited allergic reactions to ragweed pollen. However, the sensitivity developed by the mice was allergen-specific (i.e) the offspring showed no allergic reaction towards dust mites and other common allergens. So how did this happen?
Crossing Over from Mother to Fetus
According to the researchers, IgE enters the fetus via the placenta from the mother's body. Upon entering the fetus, it binds with fetal mast cells, which are immune cells that release chemicals responsible for the triggering of allergic reactions such as runny nose and asthma. Following birth, the baby mice also end up developing an allergy to the same kind of allergens as their mothers at the very first exposure; unlike adult mice who need two exposures.
It was noted that the transferred sensitivity appeared to with time. When tested at four weeks, the newborn mice exhibited sensitivity. However, they less or no reactions at six weeks. Nevertheless, laboratory studies also demonstrated that maternal IgE can bind to human fetal mast cells, suggesting that a similar crossover takes place in humans in a similar manner.
"There is currently a significant lack of knowledge on mast cells that are present early on in the developing fetus. Here, we discovered that fetal mast cells phenotypically mature through the course of pregnancy, and can be sensitized by IgE of maternal origin that cross the placental barrier. The study suggests that a highly allergic pregnant mother may potentially transfer her IgE to her baby that consequently develop allergic reactions when exposed to the first time to the allergen," said Dr. Florent Ginhoux, senior co-author of the study.
New Avenues for Treatment
The findings of the research were also supported by cellular imaging and tests, which illustrated that maternal IgE bound to fetal mast cells, thereby, initiating the release of chemicals by mast cells in response to an allergen, through the process known as degranulation. Additionally, the study also found that the transfer of IgE through the placenta required the assistance of another protein known as FcRN. Mice in whom FcRN'was deactivated, did not possess a maternal IgE attached to their mast cells. Therefore they did not develop allergies post-birth.
As nearly 10 to 30 percent of the world's population has some allergy or another, the findings of the study can help minimize and restrict neonatal allergies through the development of interventional strategies. "Our research has really exciting findings that may explain the high incidence of early onset atopic dermatitis (eczema) in children of mothers with clinically proven eczema, which parallel findings in our local birth cohort findings," said Prof. Jerry Chan, co-author of the study
Prof. Chan concluded, "From a clinical point of view, developing a further understanding in placental transfer of IgE, and the mechanism of foetal mast cell activation would be key to developing strategies to reduce the chance of eczema or other allergies from being transferred from mother to baby."
