Immunomodulation via Novel Use of TLR4 by the Filarial Nematode Phosphorylcholine-Containing Secreted Product, ES-621

Goodridge, H.S. and Marshall, F.A. and Else, K.J. and Houston, K.M. and Egan, C. and Al-Riyami, L.R. and Liew, F.Y. and Harnett, W. and Harnett, M.M. (2005) Immunomodulation via Novel Use of TLR4 by the Filarial Nematode Phosphorylcholine-Containing Secreted Product, ES-621. Journal of Immunology, 174 (1). pp. 284-293. ISSN 0022-1767

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Abstract

Filarial nematodes, parasites of vertebrates, including humans, secrete immunomodulatory molecules into the host environment. We have previously demonstrated that one such molecule, the phosphorylcholine-containing glycoprotein ES-62, acts to bias the immune response toward an anti-inflammatory/Th2 phenotype that is conducive to both worm survival and host health. For example, although ES-62 initially induces macrophages to produce low levels of IL-12 and TNF-α, exposure to the parasite product ultimately renders the cells unable to produce these cytokines in response to classic stimulators such as LPS/IFN-γ. We have investigated the possibility that a TLR is involved in the recognition of ES-62 by target cells, because phosphorylcholine, a common pathogen-associated molecular pattern, appears to be responsible for many of the immunomodulatory properties of ES-62. We now demonstrate that ES-62-mediated, low level IL-12 and TNF-α production by macrophages and dendritic cells is abrogated in MyD88 and TLR4, but not TLR2, knockout, mice implicating TLR4 in the recognition of ES-62 by these cells and MyD88 in the transduction of the resulting intracellular signals. We also show that ES-62 inhibits IL-12 induction by TLR ligands other than LPS, bacterial lipopeptide (TLR2) and CpG (TLR9), via this TLR4-dependent pathway. Surprisingly, macrophages and dendritic cells from LPS-unresponsive, TLR4-mutant C3H/HeJ mice respond normally to ES-62. This is the first report to demonstrate that modulation of cytokine responses by a pathogen product can be abrogated in cells derived from TLR4 knockout, but not C3H/HeJ mice, suggesting the existence of a novel mechanism of TLR4-mediated immunomodulation.

ORCID iDs

Goodridge, H.S., Marshall, F.A., Else, K.J., Houston, K.M., Egan, C., Al-Riyami, L.R., Liew, F.Y., Harnett, W. ORCID logoORCID: https://orcid.org/0000-0001-9545-9401 and Harnett, M.M.;
CORE (COnnecting REpositories)