Role Of Extracellular Matrix Protein 1 In Host Liver Fibrosis Induced By Echinococcus Multilocularis Infection

Objective:To explore the role of extracellular matrix protein 1（ECM1）in patients with alveolar echinococcosis（AE）and mouse liver fibrosis induced by Echinococcus multilocularis（E.multilocularis）infection.Methods:（1）Intraoperative liver samples were collected from 15 patients with AE.H&E staining was used to observe the pathological changes in liver tissue.Sirius red and Masson staining were used to detect the degree of liver fibrosis.Immunohistochemical staining was used to detect expression ofα-SMA,CD68 and ECM1 in liver tissue.Pearson correlation coefficient method was used to analyze the correlation between ECM1 expression level and the degree of liver fibrosis and CD68 expression level.（2）E.multilocularis protoscolex was collected under aseptic condition and inoculated through hepatic portal vein to establish E.multilocularis infection mild mice model.Control group mice were injected with the same amount of normal saline.Meanwhile,ECM1 knock-out mice of Kuffer cells(Lyz-cre/ECM1^flox/flox)and the control ECM1 mild mice(ECM1^flox/flox)were also used to establish E.multilocularis infection model.Liver tissue of the mice was collected at 1,6,12 and 24 weeks after infection.Pathological changes were observed by H&E staining.The degree of liver fibrosis was detected by Sirius red staining.Expression ofα-SMA and ECM1 in liver tissues was detected by immunohistochemical staining.m RNA expression level of COL1a1,COL3a1,α-SMA,Itgav and ECM1 in liver tissues of mice was detected by q RT-PCR analysis.Pearson correlation coefficient method was used for detecting the correlation between ECM1 expression level and the degree of liver fibrosis.Results:（1）Fibrous connective tissue hyperplasia and inflammatory cell infiltration were found in the peri-lesion liver tissue in patients with AE,but no obvious abnormality was found in the distal liver tissue.The positive areas of Sirius red staining,Masson staining,α-SMA,CD68 and ECM1 in the peri-lesion liver tissue were significantly higher than those in the distal liver tissue（P<0.05）.Pearson correlation analysis showed that there was positive correlation between ECM1 expression level and the degree of liver fibrosis and CD68expression level（P<0.05）.（2）Histopathological analysis showed that there was no significant lesion formed after 6 weeks of E.multilocularis infection in mice,but numerous infiltrating immune cells and hyperplasia fibrosis connective tissue were observed around the lesion.The positive areas of Sirius red,α-SMA and ECM1 staining in E.multilocularis infection group were significantly higher than those in control group at 1,6,12 and 24 weeks of infection（P<0.05）.q RT-PCR analysis demonstrated that m RNA expression of COL1a1,COL1a3,α-SMA and Itgav in E.multilocularis infection group were significantly increased compared with the control group at 24 weeks of infection（P<0.05）.Pearson correlation analysis showed that ECM1 expression level was positively correlated with positive areas of Sirius red andα-SMA staining（P<0.05）.Moreover,immunohistochemical staining showed that ECM1 expression around the lesion in Lyz-Cre/ECM1^flox/flox mice was significantly decreased than that in ECM1^flox/flox mice.At2 weeks after E.multilocularis infection,percentage of Sirius red andα-SMA positive areas in the peri-lesion liver of ECM1^flox/flox mice was significantly higher compared with Lyz-Cre/ECM1^flox/flox mice（P<0.05）.Relatively,at 4 weeks of E.multilocularis infection,there was no significant difference in the percentage of Sirius red andα-SMA postive areas between ECM1^flox/floxmice and Lyz-Cre/ECM1^flox/flox mice（P>0.05）.Conclusion:ECM1 may participate in the promotion process of liver fibrosis induced by E.multilocularis infection.Thus,ECM1 is expected to be a new target for the treatment of liver fibrosis caused by E.muitilocularis.