a b s t r a c tIn this study we aimed to identify the physiological roles of G protein-coupled receptor 84 (GPR84) in adipose tissue, together with medium-chain fatty acids (MCFAs), the specific ligands for GPR84. In mice, high-fat diet up-regulated GPR84 expression in fat pads. In 3T3-L1 adipocytes, co-culture with a macrophage cell line, RAW264, or TNFa remarkably enhanced GPR84 expression. In the presence of TNFa, MCFAs down-regulated adiponectin mRNA expression in 3T3-L1 adipocytes. Taken together, our results suggest that GPR84 emerges in adipocytes in response to TNFa from infiltrating macrophages and exacerbates the vicious cycle between adiposity and diabesity.

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Previously we have isolated the quaternary base alkaloids, magnoflorine and phellodendrine, from Phellodendri Cortex (cortex of Phellodendron amurense Rupr., Rutaceae) as the biologically active principles to suppress local graft-versus-host (GvH) reactions in mice. In this paper, we focus on phellodendrine. Phellodendrine suppressed local semisyngeneic GvH reactions and systemic allogeneic GvH reactions in X-ray irradiated recipient mice. Phellodendrine also suppressed the induction phase of sheep red blood cell (SRBC)-induced delayed type hypersensitivity in mice and tuberculin-induced delayed type hypersensitivity in guinea pigs, but did not suppress the effector phase of these reactions. Surprisingly, phellodendrine, unlike prednisolone and cyclophosphamide, did not affect antibody production in mice to SRBC. Phellodendrine was expected to be a valuable new type of immunosuppressor against the cellular immune response.

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We previously reported that Wen-Qing-Yin (Unsei-in), a traditional Chinese blended medicine, inhibited the induction phase of various kinds of delayed type hypersensitivity (DTH) and local graft-versus-host (GvH) reactions, but did not affect humoral immune responses or the effector phase of DTH in experimental animals. In another report, we demonstrated that Phellodendri Cortex (bark of Phellodendron amurense Rupr. Rutaceae) was a component having the most potent suppressive effect on the cellular immune response among the 8 medical plants composing Unsei-in. In the present study, we isolated OB-1 and OB-5 from Phellodendri Cortex as the biologically active principles to suppress local GvH reactions in mice. OB-1 and OB-5 are quaternary base alkaloids known as magnoflorine and phellodendrine, respectively. They suppressed the local GvH reaction, when given i.p. to the host mice at 5-20 mg/kg for 8 consecutive days from the day of spleen cell transfer to cause the reaction. Both OB-1 and OB-5 suppressed picryl chloride-induced delayed type hypersensitivity (PC-DTH) when given i.p. to mice at 10 and 20 mg/kg for 5 consecutive days from the day of the sensitization, but did not suppress it when given at the time of the challenge. These results suggest that OB-1 and OB-5 suppress the induction phase but not the effector phase of the cellular immune response. They are expected to have a value as a new type of immunosuppressor.

In conclusion, the results of this study indicate not only considerable therapeutic potential of CCR2 antagonists for diabetic nephropathy and atherosclerosis, but also that TLK-19705 would serve as a powerful tool in mechanistic investigation of these inflammatory diseases.

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