Inhibitory Effect And Molecular Mechanism Of Blue Honeysuckle (Lonicera Caerulea L) Extracts On Adjuvant-Induced Arthritis In Rats

In the present study, we have investigated the inhibitory effect of blue honeysuckle extracts (BHE) on adjuvant-induced arthritis (AIA) in vivo, and further clarified the underling molecular mechanism in vitro.In vivo experiments were conducted to investigate the anti-inflammatory effect of BHE in a Complete Freund’s Adjuvant (CFA) induced arthritis rat model.50six-week-old male Sprague-Dawley rats were assigned into five groups (n=10): Control group (CTL), CFA induced arthritis group (CFA), Low-dose group of BHE (CFA+BHE75), Middle-dose group of BHE (CFA+BHE150) and High-dose group of BHE (CFA+BHE300). The rats were treated with0,0,75,150or300mg·kg-1·d-1of BHE by oral gavage respectively. After the first given, arthritis was induced by injecting100μl CFA or saline as control into the right hind paw of rats. Our results demonstrated that BHE inhibited CFA-induced arthritis in a dose-dependent manner. Specially,150or300mg/kg of BHE inhibited CFA-induced rat paw edema significantly (P<0.05). The levels of inflammatory mediators including TNF-α, IL-1β, IL-6and NO were increased significantly in CFA-induced rats (P<0.05), and300mg/kg of BHE suppressed all of these mediators significantly (P<0.05). BHE also increased total antioxidant activity (T-AOC) and the levels of super oxygen dehydrogenises (SOD) and glutathione peroxidase (GSH-Px) in serum, while malonaldehyde (MDA), a production of oxidation, was decreased, CFA+BHE300group had significant difference compared with CFA group (P<0.05). In addition, three doses of BHE reduced the serum levels of glutamic-pyruvic transaminase (GPT) and glutamic oxalo acetic transaminase (GOT) in AIA rats significantly (P<0.05).To study the anti-inflammatory molecular mechanisms of BHE, we further used a lipopolysaccharide (LPS)-induced murine macrophage-like RAW264.7cell model. RAW264.7cells were pretreated with75,150,300μg/ml of BHE for30min, and then exposure to40ng/ml LPS for different times. The results indicated that the levels of TNF-a, IL-ip, IL-6and NO were increased significantly (P<0.05) in LPS-induced RAW264.7cells, and BHE reduced all of these inflammatory mediators in a dose-dependent manner, which was consistent with the results in vivo. Molecular data further clarified that BHE suppressed LPS-induced iNOS and COX-2expression by down-regulating transforming growth factor β activated kinase-1(TAK1)-mediated mitogen-activated protein kinase (MAPK) and nuclear factor κB (NF-κB) pathways with the attenuated activation of activator protein-1(AP-1) and interferon regulatory factor3(IRF3). Finally, anthocyanins in BHE were identified as bioactive compounds for these inhibitory actions by HPLC. Our findings provide the first molecular basis for the anti-inflammatory properties of BHE.This study demonstrated that BHE suppressed CFA-induced arthritis with attenuated levels of inflammatory mediators including IL-1β, IL-6, TNF-a and NO in rats. In addition, BHE improved antioxidative capacity and liver function in AIA rats. Molecular data further clarified that BHE suppressed LPS-induced production of proinflammatory mediators by down-regulating TAK1-mediated NF-κB and MAPK pathways.