Figure 1: The mechanism of cockroach allergen-induced allergic sensitization. Cockroach-derived proteases can disturb airway epithelial integrity and lead to an increased penetration of cockroach allergen, which can activate innate immune cells (e.g., dendritic cells (DCs)) via binding to Toll-like receptors (TLRs) or C-type lectin receptors. The activated DCs can direct cells of the adaptive immune system to a promotion of Th2 cell response and subsequently increase risk of sensitization. On the other hand, genetic factors, particularly genetic variants in TLRs, CLRs, CD14, either alone or in interaction with cockroach exposure, confer the susceptibility to increased risk of cockroach sensitization and subsequently inflammation in the lung and asthma.