Drs. Kanneganti and van der Meer contributed equally to this work.
Engagement of fatty acids with toll-like receptor 2 drives interleukin-1β production via the ASC/caspase 1 pathway in monosodium urate monohydrate crystal–induced gouty arthritis
Article first published online: 29 OCT 2010
Copyright © 2010 by the American College of Rheumatology
Arthritis & Rheumatism
Volume 62, Issue 11, pages 3237–3248, November 2010
How to Cite
Joosten, L. A. B., Netea, M. G., Mylona, E., Koenders, M. I., Malireddi, R. K. S., Oosting, M., Stienstra, R., van de Veerdonk, F. L., Stalenhoef, A. F., Giamarellos-Bourboulis, E. J., Kanneganti, T.-D. and van der Meer, J. W. M. (2010), Engagement of fatty acids with toll-like receptor 2 drives interleukin-1β production via the ASC/caspase 1 pathway in monosodium urate monohydrate crystal–induced gouty arthritis. Arthritis & Rheumatism, 62: 3237–3248. doi: 10.1002/art.27667
- Issue published online: 29 OCT 2010
- Article first published online: 29 OCT 2010
- Manuscript Accepted: 13 JUL 2010
- Manuscript Received: 18 FEB 2010
- NIH. Grant Number: AR-056296
- American Lebanese and Syrian Associated Charities
- Vici grant from the Netherlands Organization for Scientific Research
The concept that intraarticular crystals of uric acid by themselves trigger episodes of painful gouty arthritis is inconsistent with the clinical reality. Patients with large deposits of monosodium urate monohydrate (MSU) crystals (tophi) do not necessarily experience gouty attacks. In fact, it is the excessive consumption of food or alcohol that elicits the inflammation of the acute gout attack. The aim of this study was to identify the precise mechanism that initiates flares of gouty arthritis.
Human peripheral blood mononuclear cells (PBMCs) and murine macrophages were stimulated in vitro with MSU, free fatty acids (FFAs), or both in combination. Thereafter, production of interleukin-1β (IL-1β) and activation of caspase 1 were determined. Gouty arthritis was induced in mice with deficiencies in the genes for caspase 1, ASC, NALP3, or IL-1β, and the lack of inflammasome activity during joint swelling or other joint pathologic features was investigated in these mice.
MSU crystals had no biologic effects on PBMCs from healthy subjects, whereas the FFA C18:0 in the presence of MSU crystals induced the release of large amounts of IL-1β following engagement of Toll-like receptor 2 (TLR-2). Interaction of FFAs, but not alcohol, with TLR-2 synergized with MSU crystals to induce an inflammatory reaction. An important event of MSU/FFA-induced acute joint inflammation is the activation of the inflammasome. MSU/FFA-induced release of IL-1β was dependent on activation of caspase 1 and ASC, but surprisingly, not NALP3.
The synergistic effect between FFAs and MSU crystals leads to ASC/caspase 1–driven IL-1β release. This mechanism could explain how constitutionally derived metabolic events initiate attacks of gout via the induction of IL-1β–mediated joint inflammation.