OBJECTIVE: In gout, incompletely defined molecular factors alter recognition of dormant articular and bursal monosodium urate monohydrate (MSU) crystal deposits, thereby inducing self-limiting bouts of characteristically severe neutrophilic inflammation. To define primary determinants of cellular recognition, uptake, and inflammatory responses to MSU crystals, we conducted a study to test the role of Toll-like receptor 2 (TLR-2), TLR-4, and the cytosolic TLR adapter protein myeloid differentiation factor 88 (MyD88), which are centrally involved in innate immune recognition of microbial pathogens. METHODS: We isolated bone marrow-derived macrophages (BMDMs) in TLR-2-/-, TLR-4-/-, MyD88-/-, and congenic wild-type mice, and assessed phagocytosis and cytokine expression in response to endotoxin-free MSU crystals under serum-free conditions. MSU crystals also were injected into mouse synovium-like subcutaneous air pouches. RESULTS: TLR-2-/-, TLR-4-/-, and MyD88-/- BMDMs demonstrated impaired uptake of MSU crystals in vitro. MSU crystal-induced production of interleukin-1beta (IL-1beta), tumor necrosis factor alpha, keratinocyte-derived cytokine/growth-related oncogene alpha, and transforming growth factor beta1 also were significantly suppressed in TLR-2-/- and TLR-4-/- BMDMs and were blunted in MyD88-/- BMDMs in vitro. Neutrophil influx and local induction of IL-1beta in subcutaneous air pouches were suppressed 6 hours after injection of MSU crystals in TLR-2-/- and TLR-4-/- mice and were attenuated in MyD88-/- mice. CONCLUSION: The murine host requires TLR-2, TLR-4, and MyD88 for macrophage activation and development of full-blown neutrophilic, air pouch inflammation in response to MSU crystals. Our findings implicate innate immune cellular recognition of naked MSU crystals by specific TLRs as a major factor in determining the inflammatory potential of MSU crystal deposits and the course of gouty arthritis.
OBJECTIVE: In gout, incompletely defined molecular factors alter recognition of dormant articular and bursal monosodium urate monohydrate (MSU) crystal deposits, thereby inducing self-limiting bouts of characteristically severe neutrophilic inflammation. To define primary determinants of cellular recognition, uptake, and inflammatory responses to MSU crystals, we conducted a study to test the role of Toll-like receptor 2 (TLR-2), TLR-4, and the cytosolic TLR adapter protein myeloid differentiation factor 88 (MyD88), which are centrally involved in innate immune recognition of microbial pathogens. METHODS: We isolated bone marrow-derived macrophages (BMDMs) in TLR-2-/-, TLR-4-/-, MyD88-/-, and congenic wild-type mice, and assessed phagocytosis and cytokine expression in response to endotoxin-free MSU crystals under serum-free conditions. MSU crystals also were injected into mouse synovium-like subcutaneous air pouches. RESULTS:TLR-2-/-, TLR-4-/-, and MyD88-/- BMDMs demonstrated impaired uptake of MSU crystals in vitro. MSU crystal-induced production of interleukin-1beta (IL-1beta), tumor necrosis factor alpha, keratinocyte-derived cytokine/growth-related oncogene alpha, and transforming growth factor beta1 also were significantly suppressed in TLR-2-/- and TLR-4-/- BMDMs and were blunted in MyD88-/- BMDMs in vitro. Neutrophil influx and local induction of IL-1beta in subcutaneous air pouches were suppressed 6 hours after injection of MSU crystals in TLR-2-/- and TLR-4-/- mice and were attenuated in MyD88-/- mice. CONCLUSION: The murine host requires TLR-2, TLR-4, and MyD88 for macrophage activation and development of full-blown neutrophilic, air pouch inflammation in response to MSU crystals. Our findings implicate innate immune cellular recognition of naked MSU crystals by specific TLRs as a major factor in determining the inflammatory potential of MSU crystal deposits and the course of gouty arthritis.
Authors: Edward M Greenfield; Michelle A Beidelschies; Joscelyn M Tatro; Victor M Goldberg; Amy G Hise Journal: J Biol Chem Date: 2010-08-19 Impact factor: 5.157
Authors: Hal M Hoffman; Peter Scott; James L Mueller; Amir Misaghi; Sean Stevens; George D Yancopoulos; Andrew Murphy; David M Valenzuela; Ru Liu-Bryan Journal: Arthritis Rheum Date: 2010-07
Authors: G F Bomfim; C Echem; C B Martins; T J Costa; S M Sartoretto; R A Dos Santos; M A Oliveira; E H Akamine; Z B Fortes; R C Tostes; R C Webb; M H C Carvalho Journal: Life Sci Date: 2014-12-11 Impact factor: 5.037