烟酰胺核糖对EAE小鼠的外周抗炎作用及其机制研究

Peripheral anti-inflammatory effect of nicotinamide riboside in EAE mice

目的探讨烟酰胺核糖(NR)对实验性自身免疫性脑脊髓炎(EAE)小鼠的外周抗炎作用及机制。方法采用髓鞘少突胶质细胞糖蛋白35~55肽段(MOG35-55)诱导C57BL/6雌性小鼠制备EAE模型,随机分为EAE模型组和NR治疗组。EAE模型组每只小鼠按200μl/d剂量灌胃给予生理盐水,NR治疗组每只小鼠按500 mg/kg、200μl/d剂量灌胃给予NR,观察并记录各组小鼠临床评分和体质量。免疫后第28天处死小鼠,制备脾脏和脊髓冰冻切片,提取脊髓组织蛋白。HE染色检测外周炎性细胞浸润脊髓,免疫荧光染色检测小鼠脊髓CD4^(+)T细胞、CD68^(+)巨噬细胞数量,Western blot检测小鼠脊髓IFN-γ、IL-1β表达,免疫荧光染色检测小鼠脾脏ROCK-Ⅰ^(+)细胞、TLR4^(+)细胞、p-NF-κB^(+)细胞、TNF-α^(+)细胞、IL-1β^(+)细胞、IFN-γ^(+)细胞、IL-6^(+)细胞、IL-10^(+)细胞、IL-17^(+)细胞、i NOS^(+)细胞、Arg-1^(+)细胞数量。结果与EAE模型组相比,NR显著推迟EAE小鼠发病时间(P<0.05),降低临床评分(P<0.05或P<0.01),减轻体质量丢失,阻止外周炎性细胞浸润脊髓(P<0.01),减少脊髓CD4^(+)T细胞、CD68^(+)巨噬细胞数量(P<0.01),下调脊髓IFN-γ、IL-1β炎性因子表达(P<0.05),抑制小鼠脾脏ROCK-Ⅰ、TLR4、p-NF-κB表达(P<0.01),减少脾脏IFN-γ、i NOS、IL-6等促炎因子分泌(P<0.05或P<0.01),促进脾脏抗炎因子Arg-1、IL-10分泌(P<0.05或P<0.01)。结论NR能够有效缓解EAE小鼠临床症状,显著减轻外周和中枢神经系统炎症反应,其机制可能与抑制EAE小鼠脾脏Rho/ROCK信号通路和TLR4/NF-κB信号通路有关。

The study was designed to investigate the peripheral anti-inflammatory effect of nicotinamide riboside(NR)in experimental autoimmune encephalomyelitis(EAE)mice and its mechanisms.Female C57BL/6 mice were induced by MOG35-55 to prepare EAE model,which then randomly divided into EAE model group and NR treatment group.Mice in EAE model group were given normal saline at a dose of 200μl/d and mice in NR treatment group were given NR at a dose of 500 mg/kg(200μl/d)by intragastric administration.Clinical score and body weight of mice in each group were observed and recorded.After mice were sacrificed on the 28th day after immunization,frozen sections of spleen and spinal cord were prepared and proteins of spinal cord were extracted.HE staining was used to detect peripheral inflammatory cells infiltrating spinal cord;immunofluorescence staining was used to detect the number of CD4^(+)T cells and CD68^(+)macrophages in TNF-spinal cord of mice;Western blot was used to detect the expression of IFN-γand IL-1βin spinal cord of mice;immunofluorescence staining was used to detect the number of ROCK-Ⅰ^(+)cells,TLR4^(+)cells,p-NF-κB^(+)cells,TNF-α^(+)cells,IL-1β^(+)cells,IFN-γ^(+)cells,IL-6^(+)cells,IL-10^(+)cells,IL-17^(+)cells,iNOS^(+)cells and Arg-1^(+)cells in spleen of mice.Data showed that compared with EAE model group,NR significantly delayed the onset time of EAE mice(P<0.05),decreased clinical score(P<0.05 or P<0.01),alleviated weight loss,prevented peripheral inflammatory cells from infiltrating spinal cord,decreased the number of CD4^(+)T cells and CD68^(+)macrophages in spinal cord(P<0.01),down-regulated the expression of IFN-γand IL-1βof spinal cord(P<0.05),inhibited the expression of ROCK-Ⅰ,TLR4 and p-NF-κB in spleen of mice(P<0.01),reduced the secretion of IFN-γ,iNOS,IL-6 and other pro-inflammatory factors in spleen(P<0.05 or P<0.01),and increased the secretion of anti inflammatory factors Arg-1 and IL-10 in spleen(P<0.05 or P<0.01).In conclusion,NR can effectively alleviate the clinical symptoms of EAE mice and significantly reduce inflammatory response of peripheral and central nervous system,and its mechanism may be related to the inhibition of Rho/ROCK signaling pathway and TLR4/NF-κB signaling pathway in spleen of EAE mice.