Objectives To investigate the effect of the imbalance of Th17/Treg on egg
granuloma formation of liver with
Schistosomiasis japonicum. Methods The BALB/c mice were infected with Schistosoma japonicum cercariae to establish a model of
Schistosomiasis japonica. The blood samples, liver tissues and spleen tissue were harvested at the 2nd, 4th, 6th, 8th week, respectively. HE staining and Masson staining were performed to assess the pathological characteristics of the liver. Flow cytometry (FCM) was conducted to evaluate the proportion of CD4+ T cell subsets including Th17 cells and Tregs in liver and spleen tissue. The quantitative real-time PCR (qRT-PCR) was carried out to investigate the
mRNA level of
cytokines including RORγt, FOXP3,
IL-6,
IL-17,
IL-23 and
IL-10 in liver tissues. Finally, ELISA was performed to assess the serum level of
cytokines including
IL-6,
IL-17,
IL-23 and TGF-β. Schistosoma japonicium soluble egg
antigen (SjSEA) were prepared to stimulate mouse spleen cells in vitro. qRT-PCR was carried out to investigate the
mRNA level of
cytokine including RORγt and FOXP3 and ELISA was performed to assess the expression level of
cytokines including
IL-6,
IL-17,
IL-23 and TGF-β at different time points. Results HE and Masson staining demonstrated that inflammatory cell infiltration, schistosome egg
granuloma formation and the
collagen deposition increased in the liver tissue after the 4th week. The longer the
infection, the more severe the liver pathology. In the liver and spleen tissues, the percentage of Th17 cells of
infection group (2nd, 4th and 6th weeks) were significantly higher than the healthy group. The percentage of Tregs in the liver tissues of
infection group (4th, 6th and 8th weeks) were significantly higher than the healthy group, and the percentage of Tregs in the spleen of
infection group (2nd and 4th weeks) were significantly higher than the healthy group. Th17/Treg ratios in the liver of
infection group were lower than the healthy group. Th17/Treg ratios in the spleen of
infection group (2nd and 4th weeks) were lower than the healthy group, while it increased in the 6th week. At the same time, the levels of Th17 cells and Tregs related nuclear
transcription factors and
cytokines showed similar dynamic changes as the percentages of T cell subsets. SjSEA can induce the differentiation of Th17 and Tregs and the expression of related
cytokines and
transcription factors. Conclusion Th17 cells may play a major role in liver pathology, and the imbalance of Th17 cells/Tregs was closely related to the schistosome egg
granuloma formation.