Immunomodulators secreted from parasitic helminths act on pattern recognition receptors

Excretory-secretory (ES) products from parasitic helminths contain immunomodulatory molecules, which can regulate host immune responses. These immunomodulatory molecules are crucial for successful parasitism, and play roles in tissue migration, maturation, and reproduction. Some target pattern recognition receptors (PRRs), including toll-like receptor, C-type lectin receptor, receptor for advanced glycation end products, and nucleotide-binding oligomerization domain-like receptor. PRRs trigger activation of signaling cascades, inducing innate inflammatory responses and adaptive immunity in hosts. This article reviews ES immunomodulators identified in parasitic helminths that act on PRRs, and their PRR-facilitated immune-regulatory mechanisms. In addition, we describe the therapeutic potential of ES immunomodulators for allergic and inflammatory diseases.