Anti-inflmatory Effect And Immune-tolerance Mechanism Of Hongmasu

Objective: To explore effects of a novel dicoumarin analog (Hongmasu) isolated from Urtica dentate Hand (UDH) on the development of typeⅡcollagen (CⅡ)-induced arthritis (CIA) in BALB/c mice.Methods: BALB/c mice were immunized with an emulsion of 200mg CⅡand complete Freund's adjuvant (CFA) before or after the onset of CIA. The mice were then given a suspension of Hongmasu (60mg/kg, 40mg/kg, 20mg/kg) or saline by intragastric (i.g.) administration every day. The incidence and severity of disease and histopathology of inflammation were assessed. Inflammatory response was determined by measuring the levels of different inflammation mediators in serum. The effect of Hongmasu on differentiation of CD4~+CD25~+ Treg cells was examined by flow cytometry. The phenotype of bone marrow-derived dendritic cells (BMDC), mRNA level of DC T-bet and IL-12p70 secreted by DC were also detected. The toxicity of Hongmasu was detected by calculating IC50 of HepG2 cells in vitro.Results: Pharmacologically, treatment with Hongmasu for typeⅡcollagen induced arthritis in mouse through oral administration demonstrated significant suppressed the clinical arthritis score and paw swelling in a dose-dependent manner, compared with the untreated CIA mice. Pathologic changes showed that Hongmasu protected tissues against bone destruction, whereas an almost complete destruction occurred in CIA model group. The protective status was associated with a substantial decrease in the production of IFN-γand IL-2, an increase of IL-10 and TGF-βand suppressive expression of T-bet in BMDC. Hongmasu also induced the generation of CD4~+CD25~+ Treg cells with a Treg phenotype Foxp3. TC-treated DC was characterized as low expression of MHC classⅡand CD86 molecules, as well as a reduction of IL-12p70. The liver index and kidney index of were not affected after the treatment of Hongmasu. Hongmasu could not inhibit the proliferation of HepG2 cells.Conclusions: Our data suggests that Hongmasu provides substantial therapeutic protection against CIA by eliciting immune tolerance and it would be a valuable candidate for further investigation as a new anti-arthritic drug.