The role of LPS and CpG in the farm ef- fect against allergies, and beyond

The prevalence of allergic disease has increased significantly over the past decades. Although allergies are inherently multifactorial and heterogenous; environmental, maternal, and early life microbial exposures could strongly modify disease risk. The effects of environmental microbiota are illustrated by the "farm effect", showing protection against asthma when growing up on traditional farms. Recent studies have further revealed an important role for early-life exposure to a microbe-rich environment imposing lung and gut microbiome maturation and immune education, preventing allergic disease in childhood. Advances are made in the field of immunology and microbiome research, which identified entire microbial taxa, as well as specific microbial metabolites and bacterial products associated with reducing disease risk. Here we discuss the cross-talk between the microbiota and allergic disease pathogenesis, including bacterial products as lipopolysaccharide and CpG in the farm effect