Helminth immunoregulation: the role of parasite secreted proteins in modulating host immunity.
Helminths are masterful immunoregulators. A characteristic feature of helminth infection is a Th2-dominated immune response, but stimulation of immunoregulatory cell populations, such as regulatory T cells and alternatively activated macrophages, is equally common. Typically, Th1/17 immunity is blocked and productive effector responses are muted, allowing survival of the parasite in a "modified Th2" environment. Drug treatment to clear the worms reverses the immunoregulatory effects, indicating that a state of active suppression is maintained by the parasite. Hence, research has focussed on "excretory-secretory" products released by live parasites, which can interfere with every aspect of host immunity from initial recognition to end-stage effector mechanisms. In this review, we survey our knowledge of helminth secreted molecules, and summarise current understanding of the growing number of individual helminth mediators that have been shown to target key receptors or pathways in the mammalian immune system.
Hewitson
James P
JP
Centre for Immunity, Infection and Evolution, Institute of Immunology and Infection Research, University of Edinburgh, West Mains Road, Edinburgh EH9 3JT, UK.
Grainger
John R
JR
Maizels
Rick M
RM
D000818:Animals; D015801:Helminth Proteins / Q000502:physiology*; D006376:Helminths / Q000276:immunology* / Q000472:pathogenicity*; D006801:Humans; D007155:Immunologic Factors / Q000502:physiology*; D037521:Virulence Factors / Q000502:physiology*
D015801:Helminth Proteins; D007155:Immunologic Factors; D037521:Virulence Factors