Early life environmental exposure protection or risk for allergic diseases

The development of allergic diseases is dependent on genetic, epigenetic and environmental factors and their influence on immune regulation early in childhood. The rapid increase in recent decades underlines the importance of environmental factors. Different environmental exposures, especially in early childhood, can have distinct effects on the pathogenesis of allergic diseases depending on their type, time, duration and frequency of exposure. Environmental pollutants, aeroallergens and molds as well as delivery by caesarean section, smoking and certain early childhood infections are classified as harmful factors. In contrast, early contact to children, growing up on farms or in rural areas and a balanced diet are associated with a lower prevalence of allergies. The underlying immunological mechanisms include different cell populations and signaling pathways as well as (epi) genetic factors.