Dynamics Expression Of The Cytokine And Chemokine Associated With Th17 Cell In The Liver Of Mouse Infected With Schistosoma Japonicum

Objective: The purpose of this study was to observe the dynamic changes of inflammatory cytokines and chemokines related to Th17 cells in the liver of C57BL / 6 mouse infected with S. japonicum, and explore the role in granuloma formation. Methods: Mice were infected subcutaneously with cercariae of S. japonicum, and then sacrificed to observe the pathological changes of livers and record the liver index regularly 2, 4, 6, 8, 10 and 12 weeks following cercarial exposure. Liver samples were embedded in paraffin for routine histological examination. The sizes of egg granuloma were observed dynamically by HE stain. IL-17, IL-6, TGF-β, TNF-α, IL-23, CXCL1, CXCL2 and CCL11mRNA level in the mouse liver were measured by using real time quantitative PCR (RT-PCR); And liver IL-17, CXCL1, CXCL2 and CCL11 protein levels were determined by ELISA assay. Results: PCR (RT-PCR) analysis of cytokine messenger RNA (mRNA) expression in granulomatous livers of C57BL/6 mice infected with S. japonicum demonstrated that IL-17, IL-23, CXCL1, CXCL2, CCL11mRNA was barely detectable and closed to the basic expression of the normal control mouse two weeks following cercarial exposure, but at week 6 of infection, cytokine (IL-17, IL-23, CXCL1, CXCL2 and CCL11)mRNAs were expressed strongly, and compared with the normal controls, P <0.05; Thereafter, they began to decayed gradually, and dropped to background levels by week 12. Whereas TGF-β, TNF-αmRNA were first appeared at week 2, then gradually increased, peaked at the 8th week after exposition, compared with the control mouse, P <0.05, and subsequently reduced to low levels of expression by 12 week. In addition, IL-17, CXCL1, CXCL2 and CCL11 protein secretion level was significantly increased compared with the control mouse ( P <0.05 ) at the 6th and 8th week after exposition. The result of HE staining showed that the normal lobular architecture, portal area without egg deposition, no inflammatory cell infiltration, no fibrosis and liver cell cord radial order appear at the 2nd weeks of infection. At the 4th weeks of infection, we can see the egg granuloma, as well as a small amount of infiltrating inflammatory cell surrounded the eggs, granuloma area is (5.23±O.65)×103μm 2; At week 6 of infection, granulomatous reaction reached a peak, and accompanied with a large amounts of inflammatory cells infiltration, a broad of liver cell necrosis and a red radial structure of necrosis without substance arounding the eggs, granuloma area raised to (144.30±40.32)×103μm2; thereafter, the granuloma became smaller and we can find that a few of fibre cells were around the eggs at 8 week, and granuloma area reduced to (89.43±15.94)×103μm2 by 10 week ; The egg granuloma got smaller significantly at 12 week; furthermore, part of the liver cell degeneration, necrosis and infiltration of inflammatory cells, the small spindle-shaped fibroblasts and epithelioid cells can be seen around the eggs. Compared acute and chronic granulomatous size, the difference was statistically significant (P <0. 05) Conclusion: cytokine-17 and TNF-α, produced by Th17cell in the liver of mice infected with S. japonicum, expressed increasingly during the development of liver granuloma following soluble egg antigen stimulating the immune system of the mice, and cytokines related to Th17 cell differentiation, expansion and maintenance are also rapidly elevated at the acute phase of desease, suggesting that Th17 cell proliferation is stronger, and in accompany with high levels of interleukin-17 (IL-17) when large, vigorous granulomas are formed in the liver. Together with the data, suggested that Th17/ IL-17 may be indirectly mediate the liver egg granuloma formation. The cytokine IL-17 producted by Th17 cells can induce many pro-inflammatory cytokines and chemokines to express in the livers of mice infected with S. japonicum, inflammatory chemokines (CXCL1, CXCL2) attracted to neutrophils and CCL11 recruited eosinophils were significantly higher than control mice in the acute stage (6 weeks, 8 weeks), suggesting IL-17 may be through induction of chemokines CXCL1, CXCL2 and CCL11 expression, attract neutrophils, eosinophils to the egg deposition site, and control the infection in the development granuloma in the liver of mice infected with S. japonicum, The results show that Th17/IL-17 may be play a crucial role in the development of granuloma in the liver of the mice infected with S. japonicum.