The phosphorycholine moiety of the filarial nematode immunomodulator ES-62 is responsible for its anti-inflammatory action in arthritis

Harnett, M.M. and Kean, Dorothy E. and Boitelle, A. and McGuiness, S. and Thalhamer, T. and Steiger, C.N. and Egan, Caitlin and Al-Riyami, Lamyaa and Alcocer, Marcos J.C. and Houston, Katrina M. and Gracie, J.A. and McInnes, I.B. and Harnett, W. (2008) The phosphorycholine moiety of the filarial nematode immunomodulator ES-62 is responsible for its anti-inflammatory action in arthritis. Annals of the Rheumatic Diseases, 67 (4). pp. 518-523. ISSN 0003-4967 (https://doi.org/10.1136/ard.2007.073502)

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Abstract

In countries where parasitic infections are endemic, autoimmune disease is relatively rare, leading to the hypothesis that parasite-derived immunomodulators may protect against its development. Consistent with this, we have previously demonstrated that ES-62, a 62 kDa phosphorylcholine (PC)-containing glycoprotein that is secreted by filarial nematodes, can exert anti-inflammatory action in the murine collagen-induced arthritis (CIA) model and human rheumatoid arthritis-derived synovial tissue cultures. As a first step to developing ES-62-based drugs, the aim of this study was to determine whether the PC-moiety of ES-62 was responsible for its anti-inflammatory actions. We compared the anti-inflammatory activity of a PC-free form of recombinant ES-62 (rES-62) and a synthetic PC-ovalbumin conjugate (OVA-PC) with that of native ES-62 in the CIA model and synovial tissues from patients with rheumatoid arthritis. Results: The anti-inflammatory actions of ES-62 in CIA appear to be dependent on the PC moiety as indicated by the reduction in severity of disease and also suppression of collagen-specific T helper 1 cytokine production observed when testing OVA-PC, but not rES-62. Interestingly, the anti-inflammatory activity of PC did not correlate with a reduction in anti-collagen IgG2a levels. Also, the ES-62-mediated suppression of interferon- from human patient tissues could be mimicked by OVA-PC but not rES-62 or ovalbumin. In countries where filariasis is endemic the reduced detection of inflammatory diseases, such as rheumatoid arthritis may be because of the anti-inflammatory action of the PC moieties of ES-62. PC may thus provide the starting point for the development of novel, safe immunomodulatory therapies.