Summary and Future Directions
There have been exciting new developments in understanding the role of
the environment in mediating allergic diseases. Epigenetics has provided
us better insight into how pollution and other environmental factors
alter gene expression. Novel high throughput technologies are enabling
characterization of a healthy microbiota and the imbalance that is
created with microbial dysbiosis. This knowledge can assist with
preventative strategies that can restore a healthy microbiota. It is now
recognized that early infancy offers a ”critical window” of colonization
during which microbial communities shape immune maturation and this
window may enable opportunities for preventative treatments with pre-
and probiotics.94 In humans, this critical period
appears to be within the first 100 days of life.95 A
study found that supplementing infants with a probiotic mixture together
with at least partial breastfeeding corrected undesired changes in
microbiota composition and function caused by antibiotic treatments or
caesarean birth.96 Host microbe interactions are
highly complex and their role in medicating allergy and asthma continues
to be an area of intense research.97 Development of
tolerance towards food allergens also appears to occur at an early age.
A large study, the Learning Early About Peanuts (LEAP) study, found that
the early introduction of peanuts significantly decreased the frequency
of the development of peanut allergy among children at high risk for
this allergy.98 Current guidelines for allergy
prevention now encourage active introduction of allergenic foods to all
infants from 4-6 months of age.99
Atopic diseases have common underlying mechanisms. Epidemiological
studies show a natural history for the progression of these diseases,
starting with atopic dermatitis in early infancy and progressing to food
allergy, allergic rhinitis, and allergic asthma. This natural
progression of atopic diseases is termed the Atopic March. Studies are
now evaluating if by prevention of atopic dermatitis, we can prevent the
subsequent manifestation of other atopic diseases. In addition to the
development of targeted therapeutics, studies are determining if the use
of emollients to treat skin barrier disruption can prevent atopic
dermatitis and other atopic diseases.100
Ultimately understanding the role that genes, epigenetics, and the
environment play in shaping our immune health at the DNA, RNA, and
protein level is key to developing targeted therapies for preventing and
treating allergic diseases.