How helminths use excretory secretory fractions to modulate dendritic cells

Abstract

It is well known that helminth parasites have immunomodulatory effects on their hosts. They characteristically cause a skew toward T(H)2 immunity, stimulate Treg cells while simultaneously inhibiting T(H)1 and T(H)17 responses. Additionally, they induce eosinophilia and extensive IgE release. The exact mechanism of how the worms achieve this effect have yet to be fully elucidated; however, parasite-derived secretions and their interaction with antigen presenting cells have been centrally implicated. Herein, we will review the effects of helminth excretory-secretory fractions on dendritic cells and discuss how this interaction is crucial in shaping the host response.

Keywords: ES; TLR; Th2; dendritic cell; helminth; parasite.

Figure 1. The molecular interactions involved in DC conditioning by components found in helminth excretory-secretory products (ES) and in S. mansoni soluble egg antigen (SEA) are illustrated. ES and SEA contain a mixture of immunogenic proteins and lipids, many of which are glycosylated. Many of the most potent antigens in SEA are also found in ES. Interactions are C-type lectin (CLR) or Toll-like receptor (TLR) dependent or pattern recognition receptor (PRR) independent. DCs are polarized toward a T_H2 phenotype and Treg cells are stimulated. Each interaction is numbered based on the corresponding reference in which it was reported.