在MRSA系统性感染模型中Pam3CSK4预处理降低小鼠肾组织的炎症反应

Pretreatment with Pam3CSK4 decreases inflammation in renal tissue from mice with systemic MRSA infection

目的:在耐甲氧西林金葡菌(MRSA)系统性感染模型中,观察低剂量TLR2激动剂Pam3CSK4预处理对小鼠肾组织中炎症反应的影响并初步探讨其机制。方法:于感染前48 h、24 h对BALB/c小鼠行尾静脉注射Pam3CSK4(10μg/100μl/只);2×10~7CFU/只MRSA经静脉感染小鼠,ELISA和荧光实时定量PCR(Q-PCR)检测细胞因子水平,Q-PCR检测TLR2、IRAKs等相对表达量,Western blot检测NF-κB p65磷酸化、IRAK-M及A20表达。结果:与对照组相比,预处理组在感染6 h后肾组织中TNF-α、IL-6、IL-1β、CCL3和IFN-γ含量显著减少,i NOS表达量降低,IL-10和TGF-β表达量增高,TLR2表达下降;处理组肾组织在感染12 h后IRAK-1表达无明显增加,而IRAK-M表达量显著增加;Western blot结果显示Pam3CSK4预处理组NF-κBp65磷酸化降低,IRAK-M表达明显增高。结论:Pam3CSK4预处理降低MRSA系统性感染小鼠肾组织的炎症反应,这可能与诱导IRAK-M表达相关。

Objective： To observe whether pretreatment with Pam3CSK4,a TLR2 agonist,could decrease the inflammation response in kidney from mice with systemic MRSA infection,and to investigate the mechanism of the attenuation of inflammation with Pam3CSK4 pretreatment. Methods： BALB/c mice were pretreated with Pam3CSK4（ 10 μg/100 μl/each mouse） or PBS via tail vein once daily for two consecutive days. All mice were infected with live MRSA（ ATCC43300） at 2×10~7CFU/each mouse（ via tail vein）24 h after the second treatment. The levels of cytokines in kidney were measured by ELISA and real-time PCR,respectively. The relative expression of TLR2,IRAKs etc. were detected by real-time PCR. Western blot was performed to detect the phosphorylation of NF-κB,the expression of IRAK-M and A20,respectively. Results： The level of TNF-α,IL-6,IL-1β,CCL3 and IFN-γ in renal tissue from mice pretreated with Pam3CSK4 was decreased significantly compared with that from PBS-treated mice,respectively. Pam3CSK4 pretreatment down-regulated the relative expression of TLR2,inhibited the expression of IRAK-1 and the phosphorylation of NF-κB post infection. The expression of IRAK-M,one of the negative regulators in TLRs signaling pathway was increased significantly in renal tissue from Pam3CSK4-treated mice post infection. Conclusion： Pam3CSK4 pretreatment attenuated the inflammation response in kidney from mice with systemic MRSA infection,and these attenuation is related with up-regulation of IRAK-M.