Gouty Arthritis: Akahoshi T

Akahoshi T. · Department of General Medicine, Kitasato University School of Medicine. · Nippon Rinsho. · Pubmed #18409519 No free full text.

Abstract: Gout is a disease caused by the deposition of monosodium urate monohydrate (MSU) crystals. Precise mechanisms underlying the initiation of acute gout, however, are not known. Recent investigations provided novel evidence in the pathology of acute gout. A number of studies indicated that MSU crystals can act as a "danger signal" which resembles exogenous adjuvants, and toll-like receptor(TLR)-mediated pathways and/or MyD88-dependent IL-1 receptor pathways are involved in acute gout. Up-regulation of the triggering receptor expressed on myeloid cells 1(TREM-1) in phagocytes by the stimulation with MSU crystals has been demonstrated. Furthermore, pathological significance of NALP 3 inflammasome in gout has been also demonstrated. These findings provide a new insight into the mechanisms underlying the initiation of MSU crystal-induced acute inflammation.

Murakami Y, Akahoshi T, Hayashi I, Endo H, Hashimoto A, Kono S, Kondo H, Kawai S, Inoue M, Kitasato H. · Kitasato University School of Medicine, Sagamihara, Japan. · Arthritis Rheum. · Pubmed #14558100 links to  free full text

Abstract: OBJECTIVE: Hematopoietic prostaglandin D synthase (H-PGDS) is a key enzyme in the production of prostaglandin D and its J series metabolites. We evaluated the antiinflammatory effect of retrovirally transfected H-PGDS in order to investigate the role of H-PGDS in monosodium urate monohydrate (MSU) crystal-induced acute inflammation. METHODS: Expression of endogenous PGDS in a murine air-pouch model of MSU crystal-induced acute inflammation was determined by real-time polymerase chain reaction. H-PGDS complementary DNA (cDNA) was retrovirally transfected into C57BL/6J fibroblasts, and the cells were designated as C57-PGDS cells. Production of prostaglandins by C57-PGDS cells was measured by enzyme immunoassay. The effect of C57-PGDS cells on crystal-induced inflammation was investigated. RESULTS: Injection of the crystals caused a rapid decrease in H-PGDS expression by infiltrating cells and by the soft tissues around the air pouches. In contrast, expression of interleukin-1beta (IL-1beta) and macrophage inflammatory protein 2 (MIP-2) as well as cellular infiltration were significantly increased during the early stage of inflammation. C57-PGDS cells, but not control cells, produced an increased amount of PGD(2) in vitro, but suppressed production of PGE(2). Injection of C57-PGDS cells into air pouches inhibited cellular infiltration and MIP-2 and IL-1beta expression. CONCLUSION: In this murine air-pouch model of MSU crystal-induced inflammation, retrovirally transfected H-PGDS cDNA could reduce cellular infiltration, at least partly by inhibiting MIP-2 and IL-1beta. These findings suggest that gene therapy with H-PGDS may be useful for treating inflammatory diseases.

Akahoshi T, Namai R, Murakami Y, Watanabe M, Matsui T, Nishimura A, Kitasato H, Kameya T, Kondo H. · Department of Laboratory Medicine, Kitasato University School of Medicine, Sagamihara, Kanagawa, Japan. · Arthritis Rheum. · Pubmed #12528124 links to  free full text

Abstract: OBJECTIVE: Peroxisome proliferator-activated receptor gamma (PPAR gamma) is a member of the nuclear hormone receptor superfamily and functions as a key regulator of lipid and glucose metabolism, atherosclerosis, and inflammatory responses. This study was undertaken to evaluate the biologic role of PPAR gamma in self-limiting episodes of acute gouty arthritis. To do this, we investigated PPAR gamma expression by monosodium urate monohydrate (MSU) crystal-stimulated monocytes, and we studied the effects of PPAR gamma ligands on crystal-induced acute inflammation. METHODS: PPAR gamma expression by MSU crystal-stimulated human peripheral blood mononuclear cells was determined by reverse transcription-polymerase chain reaction and immunostaining. Expression of CD36 on monocytes was detected by flow cytometric analysis. The effects of PPAR gamma ligands on in vitro crystal-induced cytokine production and on in vivo cellular infiltration during crystal-induced acute inflammation were also investigated. RESULTS: MSU crystals rapidly and selectively induced PPAR gamma expression by monocytes. Gene expression was detected as early as 2 hours, and maximum expression was observed at 4 hours after stimulation. The induced PPAR gamma was functional, since a PPAR gamma ligand was able to up-regulate CD36 expression on monocytes. A natural ligand of PPAR gamma, 15-deoxy-Delta(12,14)-prostaglandin J(2) (15deoxy-PGJ(2)), significantly reduced the crystal-induced production of cytokines by monocytes. Indomethacin inhibited cytokine production only at high concentrations, and an antidiabetic thiazolidinedione (troglitazone) failed to exert significant effects. Administration of troglitazone and 15deoxy-PGJ(2) significantly prevented cellular accumulation in a mouse air-pouch model of MSU crystal-induced acute inflammation. CONCLUSION: Rapid induction of PPAR gamma expression on monocytes by MSU crystals may contribute, at least in part, to the spontaneous resolution of acute attacks of gout.