Effection Of The Th2Polarization Mediated By ICOS–ICOSL Signaling Pathway On The Conformation Of Hepatic Granuloma And Fibrosis In Mice Infected With Schistosoma Japonicum

The main immunopathological leisons in hosts is granulomatous inflammatoryreaction, a cellular immune response to antigens secreted by schistosome eggs, whichmay lead to cumulative hepatic fibrosis. The Th2dominant immune response inducedby Schistosoma japonicum soluble egg antigen (SEA) in chronic pathogenesis ofschistosomiasis that leads to Th1/Th2polarization and plays a key role in the formationof the hepatic egg granuloma and fibrosis.In this study, we established ICOS transgenic (ICOS-Tg) mice and ICOSLknockout (ICOSL-KO) mice as experimental schistosomiasis model for Schistosomajaponicum. To further understand how ICOS–ICOSL interaction contributes to thedevelopment of immunopathology and polarizing Th1/Th2immune responses in miceinfected with Schistosoma japonicum. Also, to analyze the Th2polarization mediated byICOS–ICOSL signaling pathway correlated with hepatic egg granuloma and fibrosisformation. Furthermore, to explore the new effective way for controlling the hepatic egggranuloma formation and the development of hepatic fibrosis.1. Expression of costimulatory molecules related with polarizing Th1/Th2immune responses in ICOS-Tg/ICOSL-KO mice infected with Schistosomajaponicum.Objective: To investigate the enhance or down-regulation of ICOS–ICOSLsignaling effection on CD28–CD80/CD86and CD40–CD154signaling pathways inICOS-Tg/ICOSL-KO mice infected with Schistosoma japonicum.Methods: The expression of CD28, ICOS and CD154on CD4+T splenocytes andof CD80, CD86, ICOSL and CD40on CD19+B splenocytes from ICOS-Tg/ICOSL-KO mice infected with Schistosoma japonicum were analyzed by flow cytometry on the daybefore infection (0week), and in early infected stage (4weeks postinfection), in acuteinfected stage (7weeks postinfection), in chronic infected stage (12weekspostinfection), in early stage of fibrosis (16weeks postinfection) and in late stage offibrosis (20weeks postinfection). The expression of costimulatory molecules oninflammatory cells around granulomatous infiltration in liver from ICOS-Tg/ICOSL-KO mice was assessed by immunohistochemical staining in the development ofschistosomiasis.Results: The flow cytometry analysis results showed that the expression of CD28on CD4+T splenocytes and of CD80and ICOSL on CD19+B splenocytes from infectedmice increased in4weeks postinfection and peaked at7weeks postinfection, thenslowly declined. Furthermore, the expression of ICOS and CD154on CD4+Tsplenocytes and of CD86and CD40on CD19+B splenocytes from infected miceincreased in4weeks postinfection and peaked at12weeks postinfection, then slowlydecreased, remained a high level at20weeks postinfection. Immunohistochemistry datashowed the expression of costimulatory molecules on inflammatory cells aroundgranulomatous infiltration in liver from ICOS-Tg/ICOSL-KO mice presented at a highlevel in7weeks postinfection, and peaked at12weeks postinfection, then slightlydeclined, but remained at high level.Compared with wildtype FVB/NJ mice, the expression of CD28, ICOS and CD154on CD4+T splenocytes and of CD80, CD86, ICOSL and CD40on CD19+B splenocytesin ICOS-Tg mice significantly increased. Morever, the expressions of costimulatorymolecules on inflammatory cells around granulomatous infiltration in liver fromICOS-Tg mice were higher than that of wildtype FVB/NJ mice.Compared with wildtype C57BL/6J mice, the expression of CD28and ICOS onCD4+T splenocytes and of CD80on CD19+B splenocytes in ICOSL-KO micesignificantly increased, however, the expression of CD154on CD4+T splenocytes andof CD86and CD40on CD19+B splenocytes in ICOSL-KO mice significantly reduced.In addition, the expression of CD28, ICOS and CD80on inflammatory cells aroundgranulomatous infiltration in liver from ICOSL-KO mice were higher than that of wildtype C57BL/6J mice, and the expression of CD154, CD86and CD40ofICOSL-KO mice were lower than that of wildtype C57BL/6J mice.Conclusion: The ICOS–ICOSL signaling pathway has a regulatory effect onCD28–CD80/CD86and CD40–CD154signaling pathway, especially for CD40–CD154signaling pathway.2. Effection of ICOS–ICOSL signaling pathway on polarizing Th2immuneresponse in ICOS-Tg/ICOSL-KO mice infected with schistosoma japonicum.Objective: To explore the enhance or down-regulation of ICOS–ICOSL signalingeffection on Th1/Th2polarization in ICOS-Tg/ICOSL-KO mice infected withSchistosoma japonicum.Methods: The spleen lymphocytes of mice were stimulated with SEA for72hourson the day before infection (0week), and at4,7,12,16and20weeks postinfection. Theconcentrations of Th1cytokines (IFN-γ, IL-12) and Th2cytokines (IL-4, IL-10, IL-13)in the culture supernatants were measured by a sandwich ELISA according to themanufacturer’s guideline. The levels of SEA-specific antibodies of IgG and its subtypes(IgG1and IgG2a) were measured in all mice sera by ELISA technology.Results: From4weeks postinfection, Th1/Th2cytokines begin increased.Moreover, the production of IFN-γ and IL-12mounted on peak at7weeks postinfection,and the production of IL-4, IL-10and IL-13boosted at12weeks postinfection, then, theproduction of all cytokines gradually reduced. The levels of SEA-specific antibodies ofIgG and its subtypes (IgG1and IgG2a) in sera changed with the development ofschistosomiasis. Especially, the levels of IgG1significantly increased at7weekspostinfection, and mounted the peak at12weeks postinfection, then slowly reduced.Furthermore, there were same changed tendency in Th2differentiation index and theratio of IgG1/IgG2a.The levels of Th2-type cytokines (IL-4, IL-13) of ICOS-Tg mice were significantlyhigher than that of wildtype FVB/NJ mice in7weeks postinfection. Compared withwildtype FVB/NJ mice, the levels of SEA-specific antibodies of IgG and its subtypes(IgG1and IgG2a) in sera of ICOS-Tg mice significantly increased. Moreover, Th2differentiation index of ICOS-Tg mice were significantly higher than that of wildtype FVB/NJ mice at7,12,16and20weeks postinfection. Also, the ratio of IgG1/IgG2a ofICOS-Tg mice were significantly higher than that of wildtype FVB/NJ mice at12and16weeks postinfection.The levels of Th1cytokines IFN-γ, IL-12of ICOSL-KO mice were higher thanthat of wildtype C57BL/6J mice in postinfection. Compared with wildtype C57BL/6Jmice, however, the levels of Th2-type cytokines (IL-4, IL-10, IL-13) significantlydecreased. Furthermore, the levels of SEA-specific antibodies of IgG and its subtypes(IgG1and IgG2a) in sera of ICOSL-KO mice significantly lower than that of wildtypeC57BL/6J mice. Moreover, Th2differentiation index of ICOSL-KO mice weresignificantly lower than that of wildtype C57BL/6J mice at4,7,12,16and20weekspostinfection. Also, the ratio of IgG1/IgG2a of ICOSL-KO mice were significantlylower than that of wildtype C57BL/6J mice at7,12and16weeks postinfection.Conclusion: The ICOS–ICOSL signaling pathway plays a key role on the Th2polarization in mice infected with Schistosoma japonicum.3. Effection of ICOS–ICOSL signaling pathway on formation of hapetic egggranuloma and fibrosis in ICOS-Tg/ICOSL-KO mice infected with schistosomajaponicum.Objective: To investigate the enhance or down-regulation of ICOS–ICOSLsignaling effection on formation of hapetic egg granuloma and fibrosis in mice infectedwith Schistosoma japonicum.Methods: The sura of mice were collected on the day before infection (0week),and at4,7,12,16and20weeks postinfection. The concentrations of HA and HYP insera were measured by a sandwich ELISA according to the manufacturer’s guideline.The granulomatous pathology in liver of ICOS-Tg/ICOSL-KO mice was dynamicallyobserved by hematoxylin and eosin (HE) staining. The fibrosis level in liver ofICOS-Tg/ICOSL-KO mice was dynamically observed by Masson staining. Theexpression of TGF-β1, α-SMA and Collagen-in liver from ICOS-Tg/ICOSL-KO micewas assessed by immunohistochemical staining in the development of schistosomiasis.Results: Pathology of hapetic tissue sections were observed and found that thevolume of hepatic egg granuloma in mice was biggest at7weeks postinfection and gradually shrinked with the development of schistosomiasis. Throughout the course, thevolume of liver egg granulomas of ICOS-Tg mice was significantly greater than that ofwildtype FVB/NJ mice, however, the volume of hapetic egg granulomas of ICOSL-KOmice was significantly smaller than that of wildtype C57BL/6J mice.With the development of schistosomiasis, the levels of HA and HYP in sera and thelevels of hapetic fibrosis and expression of TGF-β1, α-SMA and Collagen-in livergradually increased in infected mice.The levels of HA and HYP in sera of ICOS-Tg mice were significantly higher thanthat of wildtype FVB/NJ mice. Furthermore, the level of hapetic fibrosis in ICOS-Tgmice was significantly higher than that in wildtype FVB/NJ mice. Also, the expressionof TGF-β1, α-SMA and Collagen-in liver of ICOS-Tg mice were higher than that inwildtype FVB/NJ mice.The levels of HA and HYP in sera of ICOSL-KO mice were significantly lowerthan that of wildtype C57BL/6J mice. Furthermore, the level of hapetic fibrosis inICOSL-KO mice was significantly lower than that in wildtype C57BL/6J mice. Also,compared with wildtype C57BL/6J mice, the expression of TGF-β1, α-SMA andCollagen-in liver of ICOSL-KO mice was decreased.Conclusion: The ICOS–ICOSL signaling pathway has an important impact on theprocess of hapetic egg granuloma and fibrosis formation in mice infected withSchistosoma japonicum.In summary, the ICOS–ICOSL signaling pathway has a key regulatory role in Th2polarization in host infected with Schistosoma japonicum. In present study, this novelobservation has important theoretical values and potential applications to control thehapetic granuloma and to prevent the occurrence and development of hapetic fibrosis.