血吸虫病肝纤维化小鼠IL-22表达及肝星状细胞衰老的意义

Dynamic expressions of IL-22 and hepatic stellate cells senescence in mice infected with Schistosoma japonicum

目的观察血吸虫病肝纤维化小鼠模型中白介素22(IL-22)及其受体(IL-22R1)的表达状况,并对与IL-22相关的肝星状细胞(HSC)衰老机制进行探讨。方法建立血吸虫病肝纤维化小鼠模型,按感染后第4、6、8周及12周时间点取材,行生化功能检测、HE染色和Masson染色、β-半乳糖苷酶染色检测HSC衰老状况、ELISA检测肝组织中IL-22蛋白水平、荧光定量PCR检测肝组织中IL-22及IL-22R1mRNA表达水平,另设未感染小鼠为对照组。结果感染后第8、12周时血清中丙氨酸氨基转移酶和天冬氨酸氨基转移酶水平较对照组明显增高(P均<0.05)。肝组织中IL-22蛋白于感染后第4、6周时表达较对照组明显增加(P均<0.05),感染后第8周时,其表达水平较前下降,第12周时仍维持在较低水平,较第4、6周差异均有统计学意义(P均<0.01)。IL-22mRNA动态变化与蛋白水平一致,感染后第4周时表达升高,第6周时达高峰,与对照组比较差异均有统计学意义(P均<0.05),第8、12周表达持续下降,较第6周差异均有统计学意义(P均<0.05)。IL-22R1mRNA表达随病程进展逐渐升高,于12周时达高峰,较对照组、第6周差异均有统计学意义(P均<0.05)。检测发现HSC衰老,随着IL-22在晚期病程中下降,HSC衰老减少。结论 IL-22及其受体参与血吸虫病肝纤维化病程进展,早期作为炎症因子之一,参与炎症反应;至肝纤维化病程后期,可部分通过诱导HSC衰老,限制肝纤维化发展。

Objective To investigate the dynamic expressions of interleukin-22（IL-22）,Interleukin-22 receptor 1（IL-22R1）,and hepatic stellate cells（HSC）senescence in mice with Schistosoma japonicum infection. Methods A murine model of S. japonicum infection was established and the serum samples and liver tissues were collected 4,6,8,12 weeks post-infection. The serum samples were detected for the levels of alanine aminotransferase（ALT）and aspartate aminotransferase（AST）. The pathological changes and proliferation of hepatic collagen fibers in the liver tissue were observed after HE staining and Masson staining. The HSC senescence in fibrotic livers was determined by the detection of senescence-associatedβ-galactosidase（SA-β-Gal）. Sandwich ELISA was used to measure the expressions of IL-22,and Real-time PCR was used to test the mRNA levels of IL-22 and IL-22R1. The control group without S. japonicum infection was set up. Results The serum levels of ALT and AST signifi-cantly increased 8 weeks and 12 weeks after the infection（vs. 0 week,all P＆lt;0.05）. The level of IL-22 increased 4 weeks and 6 weeks after the infection（vs. 0 week,both P＆lt;0.05）,but reduced 8 weeks post-infection,and was even lower 12 weeks post-in-fection（vs. 4 weeks and 6 weeks,both P＆lt;0.01）. Being consistent with the dynamic expression of IL-22 protein,the mRNA ex-pression of IL-22 began to increase 4 weeks and reached the peak 6 weeks after the infection（vs. 0 week,both P＆lt;0.05）,and continuously declined 8 weeks and 12 weeks post-infections（vs. 6 weeks,both P＆lt;0.05）. The increase of the expression of IL-22R1 mRNA was correlated with the progression of fibrosis,and the peak was in 12 weeks post-infections（vs. 0 week and 6 weeks,both P＆lt;0.05）. The number of senescence-associated beta-galactosidase-positive HSCs was reduced with the decreasing＆amp;nbsp;expression of IL-22 in the advanced liver fibrosis. Conclusion IL-22 and IL-22R1 are involved in the pathogenesis of schistoso-miasis liver fibrosis. As an inflammation factor,IL-22 significantly increases in the early stage of fibrosis. The expression of IL-22 decreases in the late stage of fibrosis,which may contribute to HSC senescence and restrict liver fibrosis.