ABSTRACT
Objective To evaluate the role of programmed cell death ligand-1 (PD-L1) in a mouse model of bone cancer pain.Methods Ninety-six male C3H/HeN mice (20-25 g,4-6 weeks old),which inoculated with osteolytic NCTC 2472 cells,were used to build the model of bone cancer pain.Part one:sixtyfour male C3H/HeJ mice were randomly divided into sham group (group Sham,n =32) and tumor group (group Tumor,n=32).Part two:Twenty-four male C3H/HeJ mice which were inoculated with osteolytic NCTC 2472 cells were randomly divided into group T (tumor,n=8),group PD-L1 (intrathecal injection with PLX3397,1 μg/5μl,n=8) and group NS (intrathecal injection with normal saline,n=8).Also,there were eight male C3H/HeJ mice in group S which were intra-femur inoculated with α-MEM.The pain behaviors of Sham group and Tumor group were observed and the expression of PD-L1 was detected before inoculation and on 4,7,10,14 and 21 days after inoculation,including paw withdrawal mechanical threshold (PWMT) and the number of spontaneous flinches (NSF).On 14 d after inoculation,the mice of group PD-L1 and group NS were intrathecal injected with drugs respectively.Pain behaviors were observed before injection and 2,4,6,24h after injection.Results Compared with group Sham,PWMT was significantly decreased and NSF was increased on 7～ 21 d after inoculation in group Tumor (P＜0.05).Compared with baseline and group S (baseline (0.38±0.06),group Sham (0.35±0.08),(0.38±0.08),(0.36±0.07)),the expression of PDL1 was up-regulated on 10-21 d after inoculation in group Tumor ((0.77±0.06),(1.21±0.04),(1.18±0.06)) (P＜0.05).Compared with group NS,PWMT was significantly increased (group NS (0.25t0.12),(0.25±0.12),(0.31±0.12),group PD-L1 (1.43±0.49),(1.35±0.44),(0.95±0.26)),and NSF was decreased on 2-6 h after injection in group PD-L1 (group NS(11.74± 1.31),(13.78±0.0.91),(13.63±1.06),group P D-L1 (4.90± 0.82),(4.15± 0.71),(7.65±0.56)) (P＜0.05).Conclusion Expression of PD-L1 in spinal cord was up-regulated in the mouse model of bone cancer pain.Intrathecal injection of recombinant PD-L1 has an analgesic effect on mice with bone cancer.
ABSTRACT
Objective To evaluate the role of spinal neuronal Mas-related gene receptor C (MrgC) in the maintenance of bone cancer pain (BCP) in mice.Methods A total of 132 SPF male C3H/HeJ mice, aged 8-10 weeks, weighing 18-22 g, were randomly divided into 4 groups (n=33 each) using a random number table: sham operation group (S group) , BCP group, bovine adrenal medulla peptide 8-22 (BAM8-22, a highly selective MrgC agonist) group (group BAM), and MrgC antibody group (group MA).BCP was produced by injecting α-MEM 20 μl containing 2×105NCTC2472 cells into the distal medullary cavity of right femur bone.While α-MEM 20 μl was injected only in group S.The artificial cerebrospinal fluid 5 μl was injected intrathecally in S and BCP groups, and BAM 8-22 8 nmol/5 μl and MrgC antibody 5 μl were injected intrathecally in BAM and MA groups, respectively, once a day for 7 consecutive days starting from the day 14 after inoculation of the tumor cells.At 1 day before inoculation (T0), before administration (T1) , and at 14, 16 19 and 21 days after inoculation (T2-5, at 0.5 h before the initial administration and 2 h after each administration) , the number of spontaneous flinches (NSF) and mechanical paw withdrawal threshold (MWT) were measured.Five animals selected from each group at each time point were sacrificed, and the lumbar enlargement segments of the spinal cord were removed for determination of MrgC expression in the spinal neurons (by immunofluorescence).Results Compared with group S, NSF was significantly increased, MWT was decreased, and the expression of MrgC was up-regulated at T1-5 in BCP, BAM and MA groups.Compared with group BCP, NSF was significantly decreased, MWT was increased, and the expression of MrgC was up-regulated at T2-5 in group BAM, and NSF was significantly increased, MWT was decreased, and the expression of MrgC was down-regulated at T2-5 in group MA.Conclusion Spinal neuronal MrgC is involved in the maintenance of BCP in mice.