Hyun-Hee Shin

Recombinant glucocorticoid induced tumor necrosis factor receptor (rGITR) induces NOS in murine macrophage.

Glucocorticoid induced tumor necrosis factor receptor (GITR) is a new member of the tumor necrosis factor–nerve growth factor receptor superfamily of which the function has not been well studied. The extracellular domain of GITR was produced in Escherichia coli and purified as a single band of predicted M r of 18.0 kDa. GITR and GITR ligand were expressed constitutively on the surface of Raw 264.7 macrophage cell line and murine peritoneal macrophages. An extracellular domain of GITR can activate murine macrophages to express inducible nitric oxide synthase and to generate nitric oxide in a dose‐ and time‐dependent manner.

Soluble glucocorticoid‐induced tumor necrosis factor receptor (sGITR) increased MMP‐9 activity in murine macrophage

Glucocorticoid induced tumor necrosis factor receptor (GITR), a new TNFR family, increased production of matrix matalloproteinase (MMP‐9) in murine macrophages. Murine macrophages produced a band of gelatinolytic activity at 100 kDa when stimulated for 18 h with soluble GITR. MMP‐9 was identified by gelatin zymography and Western blot. Previous results demonstrated that murine macrophages express GITR and GITR ligand constitutively. Induction of MMP‐9 was synergistic with co‐treatment of INF‐γ. MMPs could play a critical role in progression and promotion of tissue injury after inflammation stimulated by GITR/ligand system. J. Cell. Biochem. 88: 1048–1056, 2003.

Rutin inhibits osteoclast formation by decreasing reactive oxygen species and TNF-α by inhibiting activation of NF-κB

Rutin, a glycoside of flavonol, inhibits osteoclast formation induced by receptor activator of NF-κB ligand (RANKL) in bone marrow-derived macrophages. It reduces reactive oxygen species produced by RANKL and its inhibitory effect results from reduced levels of TNF-α. Rutin also lowers NF-κB activation in response to RANKL.

Enhanced osteoclastogenesis in 4-1BB-deficient mice caused by reduced interleukin-10.

Enhanced osteoclastogenesis was observed in bone marrow—derived macrophage cells from 4‐1BB—deficient mice than in those from wildtype mice. 4‐1BB and 4‐1BB ligand interaction may play a role at a certain stage of osteoclast formation through increased level of IL‐10, a negative regulator of osteoclastogenesis.

A signal through 4-1BB ligand inhibits receptor for activation of nuclear factor-κB ligand (RANKL)-induced osteoclastogenesis by increasing interferon (IFN)-beta production

We tested whether any intracellular signals are transmitted through 4‐1BB/CD137 ligand (4‐1BBL), using a 4‐1BB‐Fc fusion protein and 4‐1BB‐deficient mice. Immobilized 4‐1BB‐Fc fusion protein strongly inhibited osteoclastogenesis induced by macrophage colony‐stimulating factor (M‐CSF) and receptor activator of nuclear factor‐κB ligand (RANKL) derived from bone marrow macrophages (BMM). Incubation of BMM with M‐CSF increased 4‐1BBL mRNA and surface expression of 4‐1BBL protein. Cross‐linking 4‐1BBL with immobilized 4‐1BB‐Fc also dramatically reduced the number of tartrate‐resistant acid phosphatase (TRAP)‐positive multinuclear cells (MNC) derived from the BMM from 4‐1BB‐deficient mice, suggesting that the inhibitory effect of immobilized 4‐1BB on osteoclastogenesis is due to a signal through 4‐1BBL. Reverse signaling by 4‐1BB‐Fc increased the level of interferon (IFN)‐β in BMM and neutralization of IFN‐β reversed the inhibitory effect of immobilized 4‐1BB‐Fc. Inhibition of osteoclastogenesis by immobilized 4‐1BB‐Fc is, therefore, at least in part, due to elevation of the level of the negative regulator, IFN‐β in BMM.

Soluble glucocorticoid-induced TNF receptor (sGITR) induces inflammation in mice

Glucocorticoid-induced TNF receptor (GITR) was a new member of the TNF/nerve growth factor receptor (TNFR/ NGFR) family and induced in murine T cells by dexamathasone. Recombinant soluble GITR (sGITR) induced an inflammation in peritoneal membrane and changes in spleen after i.p. injection of 3 mg/kg in C57BL/6 mice. Spleen was enlarged and percentage of neutrophils and monocytes were increased. The area of red pulp in spleen was increased, while that of white pulp was decreased after GITR injection. The thickening of membrane and neutrophil infiltration was observed in peritoneal membrane with increased myeloperoxidase activity. At later time, neutrophil infiltration moved to inside the tissue with tissue damage. GITR ligand and GITR were expressed constitutively on the surface of spleen cells and cells from peritoneal fluid. In contrast, no significant change in the spleen and in peritoneal membrane was observed in mice treated with LPS. GITR may play a role in bodys inflammatory processes.

Absence of 4-1BB increases cell influx into the peritoneal cavity in response to LPS stimulation by decreasing macrophage IL-10 levels.

Peritoneal injection of lipopolysaccharide (LPS) increased the influx of polymorphonuclear leukocytes and macrophages into the peritoneal cavity (PEC), with significantly higher cell numbers in the 4‐1BB‐deficient (KO) mice than in wild‐type (WT) mice. The peritoneal macrophages of KO mice contained less IL‐10 transcripts and protein than those of WT after LPS treatment, and immobilization of 4‐1BB‐Fc increased the level of IL‐10. Injection of IL‐10 resulted in lower cell numbers into the PEC of KO mice, suggesting that lower level of IL‐10 is responsible for stimulated cell influx in KO mice due to lack of 4‐1BB and 4‐1BBL interaction.

Corn Silk Induced Cyclooxygenase-2 in Murine Macrophages

Stimulation of murine macrophages with corn silk induced cyclooxygenase (COX)-2 with secretion of PGE2. Expression of COX-2 was inhibited by pyrolidine dithiocarbamate (PDTC), and increased DNA binding by nuclear factor kappa B (NF-κB), indicating that COX-2 induction proceeds also via the NF-κB signaling pathway. A specific inhibitor of COX-2 decreased the expression level of inducible nitric oxide synthase (iNOS) stimulated by corn silk. PGE2 elevated the expression level of iNOS, probably via EP2 and EP4 receptors on the surface of the macrophages.