Role of Antibiotics and Infection-Host Interactions in the Prevalence ofRespiratory Atopy: Experience and Perspective

We have witnessed a dramatic increase in the prevalence of respiratory allergies during the last decades. The role of infections in the prevalence of respiratory allergic diseases is attributed to the antagonism between: a) induction of T helper (Th) 1 immune response by human organism; and b) manipulation of the human immune response toward Th2 profile by common infective agents in order to increase their surviving opportunity. This review proposes an important role of massive antibiotics exposure during neonatal and early childhood on the increasing epidemiological trend. It is be- lieved that the antibiotics exposure during early childhood has also provided better surviving opportunity for atopic indi- viduals with an inadequate immune defense against common infections, deviating therefore the genetic background of general population toward Th2 profile. Taking this into account, we suggest that Th2 profile frequency (and consequently atopic phenotype prevalence) can be increased along an individual lifespan after initial massive antibiotic introduction, until the entire population is exposed to them during childhood. This hypothesis may explain findings on epidemiological surveys, which report a prevalent increase among adults in industrialized countries between 1970s and 2000s, while in re- cently-developed countries this trend begun only at the end of 1980s. These arguments may lead to the conclusion that in- fections will manipulate the human immunity along generations, whereas actual antibiotics can increase the prevalence of respiratory allergies among a population only along an individual longevity. These findings may be beneficial in the de- velopment of future strategies for management of respiratory allergic or infective pathologies.