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.