Schistosoma japonicum infection induces macrophage polarization

The role of macrophages （MФ） as the first line of host defense is well accepted. These cells play a central role in orchestrating crucial functions during schistosomal infection. Thus, understanding the functional diversity of these cells in the process of infection as well as the mechanisms underlying these events is crucial for developing disease control strategies. In this study, we adopted a Mqb polarization recognition system. M1 macrophage was characterized by expressing CD16/32, IL-12 and iNOS. M2 macrophage was characterized by expressing CD206, IL-10 and arg-1. In vivo （mouse peritoneal macrophages of different infection stages were obtained） and in vitro （different S. japonicum antigens were used to stimulate RAW264.7） were characterized by using the above mentioned system. NCA and ACA stimulated RAW264.7 express significantly higher levels of IL-12 while significantly higher levels of IL-10 were detected after soluble egg antigen （SEA） stimulation. The results showed that dramatic changes of antigen in the microenvironment before and after egg production led to macrophage polarization. Furthermore, through TLR blocking experiments, the TLR4 signaling pathway was found to play a role in the process of macrophage polarization toward M1. Our data suggest that macrophage polarization during S. japonicum infection had significant effects on host immune responses to S. japonicum.

Ultraviolet-attenuated cercariae ofSchistosoma japonicum fail to effectively induce a Th1 response in spite of up-regulating expression of cytotoxicity-related genes in C57BL/6 mice

Objective： To better understand the reason that Schistosoma japonicurn （S. japonicum） ultraviolet （UV）- radiated cercariae could not induce high level of protection in C57BL/6 mice. Methods： Microarray technology was performed to investigate the gene transcription profile in skin draining lymph nodes （sdLNs） at 1 w after exposure to attenuated cercariae （AC） or normal cercariae （NC） of S. japonicum in C57BL/6 mice. The expressions of some representative genes were further confirmed by real-time PCR. Subsequently, the expressions of Th1/Th2 cytokine genes, cytotoxicity-related genes, as well as co-stimulator genes in spleens from AC-vaccinated and NC- infected mice were analyzed by real-time PCR at w 3 and 6 post-exposure. Results： The gene expressions of Th1 cytokines, including interferon-y （IFN-γ）, interleukin （IL）-12 and tumor necrosis factor-α （TNF-α） in the sdLNs were significantly lower in AC-vaccinated mice than in NC-infected mice. Furthermore, the gene expressions of Th1- and Th2- cytokines, including IFN-γ, IL-12, TNF-α, IL-4 and IL-10, in the spleens from AC-vaccinated mice showed little changes at w 3 and 6 post-vaccination. In addition, cytotoxicity-related molecules including granzyme A, granzyme B, granzyme K, perforin 1 and Fas L were up-regulated from the early stage of vaccination, and peaked at the 3rd w after vaccination with UV-AC. Conclusion： UV-AC of S. japonicum could not ef- fectively induce a Thl response in C57BL/6 mice, which may be an explanation for the low protection against parasite challenge, and the role played by up-regulated expression of cytotoxicity-related genes in mice needs to be further investigated.

Antigen presenting cells may be able to distinguish between normal and radiatedSchistosoma japonicum cercaria:anin vitro observation

Objective： To observe the discrepancies of responses induced by Schistosoma japonicum （S. japonicum） normal cercaria antigen （NCA） and ultraviolet （UV） -radiation-attenuated cercaria antigen （UVACA） in an in vitro system. Methods： S. japonicum cercariae were collected and UVACA and NCA were prepared. Mouse macro- phage model cells （RAW 264.7） were treated with medium, NCA （40 μg/mL） or UVACA （40 μg/mL） in the presence or absence of recombinant mouse interferon gamma （rmIFN-γ; 4 ng/mL） for 48 h. Cell surface staining and flow cytometry were used to assess the major histocompatibility complex （MHC） Ⅱ expression, and data were expressed as mean fluorescence intensities （MFI）. Interleukin （IL） -10, IL-6 and prostaglandin E2 （PGE2） in cell culture supernatant were evaluated by commercial enzyme-linked immunosorbent assays. Results： NCA significantly suppressed IFN-7-induced MHC Ⅱ expression on RAW 264.7 cells. In the presence of 1FN-7, NCA significantly promoted IL-6, IL-10 and PGE2 secretion from RAW 264.7 cells. In the presence of IFN-γ, UVACA significantly promoted IL-10 but not IL-6 and PGE2 secretion from RAW 264.7 cells and showed no effect on IFN-γ-induced MHC Ⅱ expression. Compared with UVACA, NCA significantly suppressed IFN-γ-induced MHC Ⅱ expression and significantly promoted IL-6, PGE2 and IL-10 secretion from RAW 264.7 cells. Conclusion： RAW 264.7 cells respond differently to NCA and UVACA. NCA can significantly suppress IFN-γ-induced MHC Ⅱ expression and significantly promote IL-6, IL-10 and PGE2 secretion from RAW 264.7 cells compared with UVACA.

IFN-inducible p47 GTPases display differential responses to Schistosoma japonicum acute infection

Interferon gamma induced GTPase(IGTP)(also named lrgm3)and interferon gamma inducible protein 47(IRG-47)(also named lIrgd)are interferon(IFN)-inducible p47 GTPases that have been shown to regulate host resistance to intracellular pathogens.Little knowledge has been known about the role of p47 GTPases in host responses against extracellular pathogens.To investigate possible roles of IGTP and IRG-47 in the course of Schistosoma japonicum infection,IGTP and IRG-47 knockout and wild-type(WT)mice were challenged with cercariae of S.japonicum,and host responses were analyzed.At the acute stage of S.japonicum infection,mice that lacked IGTP displayed similar parasite burden and pathological damage to WT mice.Importantly,S.japonicum-infected lRG-47-deficient mice,in contrast to IGTP-deficient mice and WT mice,showed significantly reduced worms and lower egg-burden,but intense granulomatous reaction evoked by schistosome eggs in peripheral parts of liver lobes.In addition,upregulation of inflammation-related gene expression was observed in the spleen of IRG-47-deficient mice using oligonucleotide microarrays,in which multiple pathways of cytokine-cytokine receptor interaction,T-cell receptor signaling,complement,coagulation cascades and cell adhesion molecules were highlighted.Taken together,these data suggest that IGTP and IRG-47 might have distinct features that were differentially required for resistance to S.japonicum.