Role of activated cannabinoid receptor 2 in lipopolysaccharide-induced secretion of RAW264.7 macrophage inflammatory cytokines and its possible mechanism / 中华急诊医学杂志

ABSTRACT

Objective To investigate the role of activated cannabinoid receptor 2 (CB2R) in lipopolysaccharide (LPS)-induced secretion of RAW264.7 macrophage inflammatory cytokines and its possible mechanism. Methods Macrophages were seeded in 6-well plates (2 mL/well) at the density of 1×105 cells/mL and randomly divided into four groups (n=6 each group) control group (group C), LPS group (group LPS), LPS plus CB2R agonist HU308 group (group LPS+HU308), and LPS plus HU308 plus 3-Methyladenine group (group LPS+HU308+3-MA). LPS with the final concentration of 1 μg/mL were added in group LPS, group LPS+HU308 and group LPS+HU308+3-MA. After incubation for 15 min, 3-MA with a final concentration of 10 mmol/L was added into group LPS+HU308+3-MA . HU308 with the final concentration of 10 μmol/L was added in group LPS+HU308 and group LPS+HU308+3-MA at 15 min after 3-MA intervention, and the cells were then incubated for 24 h. The concentrations of TNF-α, IL-18 and IL-1β in supernatant serum of each group were determined by ELISA. The expressions of ICAM-1 and NLRP3 mRNA were detected by RT-PCR. The expressions of LC3 and Beclin1 were detected by Western blot, and the ratio of LC3-Ⅱ/LC3-Ⅰ was calculated. LSD-t test was used for sample pairwise comparison, and one way ANOVA for inter-group comparison. A P<0.05 was considered statistically significant. Results Compared with group C, the concentrations of TNF-α [(228.86±10.20) pg/mL vs (140.05±5.54) pg/mL], IL-1β [(363.62±8.14) pg/mL vs (244.82±9.11) pg/mL], and IL-18 [(293.28±13.57) pg/mL vs (202.84±9.54) pg/mL] in supernatant serum were increased (all P<0.05), the expressions of ICAM-1 [(5.88±0.32) vs (1.00±0.03)] and NLRP3 [(8.07±0.93) vs (1.01±0.05)] mRNA were increased (all P<0.05), the expressions of LC3-Ⅱ/LC3-Ⅰ ratio [(0.50±0.03) vs (0.40±0.06)] and Beclin1 [(0.51±0.04) vs (0.16±0.03)] were up-regulated in group LPS (all P<0.05). Compared with group LPS, the concentrations of TNF-α [(165.44±7.07) pg/mL], IL-1β [(272.09±3.35) pg/mL] and IL-18 [(220.41±6.01) pg/mL] in supernatant serum were significantly decreased (all P<0.05), the expressions of ICAM-1 [(3.21±0.35)] and NLRP3 [(1.54±0.30)] mRNA were decreased (all P<0.05), the expressions of LC3-Ⅱ/LC3-Ⅰ ratio [(0.71±0.03)] and Beclin1 [(0.71±0.02)] were up-regulated in group LPS+HU308 (all P<0.05). Compared with group LPS+HU308, the concentrations of TNF-α [(197.06±5.59) pg/mL], IL-1β [(318.98±11.54) pg/mL] and IL-18 [(243.33±8.71) pg/mL] in supernatant serum were significantly increased (all P<0.05), the expressions of ICAM-1 [(4.04±0.21)] and NLRP3 [(5.87±0.77)] mRNA were increased (all P<0.05), the expressions of LC3-Ⅱ/LC3-Ⅰ ratio [(0.44±0.08)] and Beclin1 [(0.32±0.03)] were down-regulated in group LPS+HU308+3-MA (all P<0.05). Conclusions Activation of cannabinoid receptor 2 can alleviate LPS-induced the secretion of RAW264.7 macrophage inflammatory cytokines, and its mechanism may be related to enhanced autophagy.