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Semin Immunol. 2014 Aug;26(4):329-40. doi: 10.1016/j.smim.2014.06.003. Epub 2014 Jul 11.

Host protective roles of type 2 immunity: parasite killing and tissue repair, flip sides of the same coin.

Author information

1
Centre for Immunity, Infection & Evolution, School of Biological Sciences, University of Edinburgh, Edinburgh, UK. Electronic address: j.allen@ed.ac.uk.
2
Centre for Immunity, Infection & Evolution, School of Biological Sciences, University of Edinburgh, Edinburgh, UK.

Abstract

Metazoan parasites typically induce a type 2 immune response, characterized by T helper 2 (Th2) cells that produce the cytokines IL-4, IL-5 and IL-13 among others. The type 2 response is host protective, reducing the number of parasites either through direct killing in the tissues, or expulsion from the intestine. Type 2 immunity also protects the host against damage mediated by these large extracellular parasites as they migrate through the body. At the center of both the innate and adaptive type 2 immune response, is the IL-4Rα that mediates many of the key effector functions. Here we highlight the striking overlap between the molecules, cells and pathways that mediate both parasite control and tissue repair. We have proposed that adaptive Th2 immunity evolved out of our innate repair pathways to mediate both accelerated repair and parasite control in the face of continual assault from multicellular pathogens. Type 2 cytokines are involved in many aspects of mammalian physiology independent of helminth infection. Therefore understanding the evolutionary relationship between helminth killing and tissue repair should provide new insight into immune mechanisms of tissue protection in the face of physical injury.

KEYWORDS:

Eosinophils; Helminths; IL-4Rα; Macrophages; Th2 cells; Wound repair

PMID:
25028340
PMCID:
PMC4179909
DOI:
10.1016/j.smim.2014.06.003
[Indexed for MEDLINE]
Free PMC Article

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