2.2 Animal studies
Mdr2−/− mice (7 weeks old, 20-22 g, male and female) were housed and maintained under specific pathogen-free conditions in a standard environment with a 12-hour light–dark cycle and fed a diet of normal chow ad libitum . All animal studies and procedures were sanctioned by the Institutional Animal Care and Use Committee of Beijing University of Chinese Medicine and performed in compliance with all guidelines and regulations. After acclimatization for 1 week, mice were randomly divided into 4 groups (n = 6): (1) wild type (WT) group; (2) Mdr2−/− group; (3) Mdr2−/− + PIC Ⅱ low dose (L) group (5 mg/kg); (4) Mdr2−/− + PIC Ⅱ high dose (H) group (10 mg/kg). Mice in group (1) and (2) were given saline and mice in groups (3)-(4) were administrated with two different doses of PIC Ⅱ for 14 days. In the macrophage depletion experiment, mice were randomly divided into 4 groups (n = 6): (1) WT group; (2) Mdr2−/− + empty liposome (Neg) group; (3) Mdr2−/− + clodronate liposome (CL) group; (4) Mdr2−/− + CL + PIC Ⅱ group (10 mg/kg). Mice in group (2) were given empty liposome and mice in groups (3)-(4) were administrated with clodronate-liposomes (1 mg/ml, 50 μl/mouse, YEASEN, Shanghai, China) through tail vein once every three days until the day before sacrificed. Mice in group (4) were also administrated with 10 mg/kg PIC Ⅱ for 14 days. After treatment, all mice in different groups were sacrificed to obtain blood and liver samples for following experiments.