| Schistosomiasis remains a major public health problem affecting some 200 million people in many parts of the developing world. Although chemical treatment has well effective in our country, we faced these reinfection and chemical resistence problems. Development of a vaccine against the disease remains a worth-while and desirable goal in view of controlling the trans- mission of schistosomiasis .Although the 6 promised vaccines by WHO (Sm97、GST、rIrVs、Sm23、TPI and Sm14) candidates against S. japonicum have been studied so far, none of them have more than 40% affective rate and been proven to be as effective as irradiated cercariae, the gold standard in terms of an experimental anti-schistosome vaccine.Schistosomiasis vaccine development, another alternative means and strategies to induce a state of natural infection does not appear normal immune response, in order to produce a high level of protection force. Studies show that the attenuated vaccine is all sera of schistosome vaccine for the protection of the strongest of the extent which rendered attenuated early stage in the invasion of local skin, skin, lymph nodes and lungs caused by strong stimulation of the immune response and induction of a factor protective immunity. It is generally believed that the human body in the whole process of schistosomiasis infection in the development of the host immune response through at least three changes of phase, the first 3 to 5 weeks after infection, the host exposed to the migration of schistosomula,express the dominant Th1 response presented,to 5 to 6 weeks, when the adults began to lay eggs, Th1 response decreased and showed dominant Th2 response, in subsequent infection into the chronic phase, Th2 response was significantly regulation, if the radiation-attenuated cercariae enter the body, it can not develop into adult worms and lay eggs,In this process, the attenuated parasite morphology, developmental, biological behavior (migration speed) and the antigen composition compared with normal cercariae, significant changes have occurred:Cercariae palate, urge sympathy sucker swollen; body contraction; end was wrinkled like change; neural coordination of muscle damage, the length of time remaining in the skin, the body of the migration was "cut" short, some remain in the skin, the rest of the farthest can migrate to the lung. After increasing the radiation dose resulted in only a limited period of migration of the skin and can not be effectively attenuated the induction of immune protection, it is caused by the weak child of the migration of worms in the lung induced an effective immune effect on the more important. Recent studies also show that the schistosomula of lung stage may produce high protective immune response and have important part. Comparison of UV irradiation attenuated Schistosoma mansoni cercariae and Sm23 (Schistosoma mansoni membrane protein)-induced mice (C57BL/6) produced protective immune response and the similarities and differences, the protective groups were 60% and 45% , significant differences appear in the lung of inflammatory response, attenuated the lung of immune inflammatory reaction, mononuclear cells accumulated in the vicinity of inflammatory lesions, and associated with the migration of Juvenile worms. Attenuated in the immune system before migrating to the major, such as spleen, thymus, and migration in the body before the need for some distance, the protective response mainly from the skin, draining lymph nodes to the lungs caused by the combined result of various effects of reaction. The three parts of the immune response induced by various forces on the protection of vital cells from the Th1 to Th2 regulatory activities related to the antibody response.Dendritic cells (Dentric cell, DC) is currently the most powerful known antigen presenting cells (antigen presenting cell, APC), in congenital, acquired immune role as a bridge between the play better. CD11c molecule is theαX subunit molecular weight of 150kDβ2 integrin family, is widely used dendritic cell specific marker, but also DC maturation is one of the important surface markers, the expression of some representatives of local organizations to aggregation in DC. T cells are the immune response of the central link for rejection of non-material strength has been mainly caused by the immune system of its activation of the decision. Determine the degree of T cell activation status of immune function key indicators. CD25 molecular gp55kD, also known as IL-2Rα, composed of high affinity IL-2 receptor, to promote the growth of T cells, activated T cells is an important symbol of the molecules, the molecular expression testing may reflect the activation of T cells. The ultraviolet radiation in the establishment of Schistosoma japonicum induced by weak immune BALB / c mouse model, we focused on immune responses in mice immunized with the early stages - mice infected with attenuated cercariae remain in the lungs and pathological changes caused by the immune.The mechanism of induction of immune protection may be on the spleen and lung cells CD11c dendritic cell surface molecule expression and T cell activation response characteristics.Study of mice immunized with attenuated cercariae play a decisive role models of lung schistosomula induced lung tissue and the immune response induced by pathological T cells in the spleen and other immune organs and peripheral blood immune response characteristics. In addition, this study extend the observation time to attenuated cercariae immunized mice against infection of the liver after 6～8w granuloma formation of CD4~+CD25~+Foxp3~+Treg cells in normal infected mice and mice immunized against the infection of differential expression analysis characteristics of the induction of immune responses and its possible mechanism, and thus the currently accepted maximum immune protection induced by the vaccine - attenuated cercariae irradiated immune response and provide a reference for the schistosomiasis control.PartⅠStudy on the protection of BALB /c mice vaccinated with UV-attenuated Schistosoma japonicum cercariaeObjective To investigate the protection against Schistosoma japonicum(S.j)infection induced by UV-attenuated S. j cercariae in BALB/c mice.Methods The protection induced by appropriate attenuated cercariae infected on the abdomen skin of the BALB /c mice.3 weeks later the normal cercariae infected the mice again and the control group without any immunization was infected too. The reduction of eggs in liver and the worms were calculated and immune response in the liver and the worms development were observed.Results The results showed that the hepatic total eggs reduction rate induced by attenuated cercariae was 51.16%and the worm reduction rate was37.90%. In the immunized group, the development of S.j is delayed and the liver egg- granulomas are reduced. UV-attenuated S. j cercariae can induce middle level of protection in BALB/c mice.Conclusion It suggested that BALB/c mice might be a moderately responder to UV-attenuated S. j cercariae. PartⅡUV-attenuated cercariae of Schistosoma japonicum infection in mice induced lung tissue response and worm scanning electron microscopy observationObjective To find out how the ultraviolet (UV) attenuation (UV-attenuated) cercariae can induce high protective responses in mouse.Methods Scanning electron microscopical(SEM) studies on Schistosoma japonicum cercariae exposed to UV attenuation and lung-stage schistosomulum developed from the UV-attenuated cercariae were done.Results The present observations showed that there were no significant changes on the surface of S. japonicum cercariae exposed to UV. But the schistosomula or adults worm that developed from the attenuated cercaria in the mice were apparently damaged.Conclusion Scanning electron microscope found that ultraviolet radiation attenuated cercariae and normal cercariae slightly different form, this two groups of mice were infected with cercariae attenuated schistosomula in the lung of normal mice can not mature, developed the ultraviolet attenuated cercariae come attenuated lung-stage schistosomula may be associated with attenuated cercariae induced host immune response is not entirely direct irradiation damage; attenuated cercariae of stay longer in the lungs, causing damage mainly to the pathology in the lungs diffuse hemorrhage, inflammatory cell infiltration, eosinophilic abscess formation of the pathological changes of the lung, the lungs may be related to the pathological changes in mice immunized with attenuated cercariae induced high immune protection mechanism. PartⅢDynamic changes of IgG levels and passive transfer of resistance with sera from BALB/c mice vaccinated with attemuated cercariae of Schistosoma JaponicumObjective To resaerch if the sera from BALB/c mice vaccinated with UV-attenuation cercariae of Schistosoma Japonicum can reduced the protecting resistance.Methods BALB/c mice were vaccinated multiply with ultraviolet-attenuated cercariae of Schistosoma japonicum, of which the levels of IgG antibody in serum were observed dynamically. At the same time, sera with vaccinated BALB/c mice transferred passively to another group of BALB/c mice at different time to detect the resistance.Results The results showed attenuated BALB/c mice sera conferred significant levels of protection (55%) when transferred before challenge.Conclusion The results suggested that antibody might play an important role in the protective immunity elicited by UV-attenuated Schistosoma japonicum cercariae multiply.PartⅣDynamic changes of early immune response in BALB/c mice vaccinated with UV attenuated Schistosoma japonicumObjective To explore the dynamic changes of early stage immune responses in the BALB/c mice vaccinated with UV-attenuated Schistosoma japonicum.Methods The mice were divided into two groups in average except 14 acted as the group of day 0 (naive). Each mouse was infected with 80±2 normal cercariae in Group One while each was vaccinated with 80±2 attenuated cercariae in Group Two. All mice were infected or vaccniated through abdoman skin. On days 4,7,14,21 days after the exposure, seven mice were sacrificed respectively in each group and the abdoman skin and the lungs were collected to stain with HE to observe dynamic changes of inflammation and the other halves were dealth with immunohistochemistry to observe the expression of CD11c.Results Inflammation of the skins derived from mice infected with boamal cercariae fell off gradually after it got to peak on day 7 and received on the whole on day 21. However as the attenuated abdoman skin were concerned, the immune response did not get the strongest until day 14 and still intensive on day 21.Conclusion Compared with the infection with normal cercariae, immune responses induce by attenuated cercariae are longer and more intensive. 7,14,21 days after infection in the attack, attenuated cercariae Representative immunohistochemistry of lung dendritic cell maturation molecule CD11c positive cells were higher than those infected with the control group, suggesting that the lungs could be attenuated cercariae antigen to raise more presenting cells and to the activation, 14,21 days after infection, caused by weak T cell activation cercariae group represents the degree of CD3 + CD25 + / CD3 + T infection rate was also higher than the normal control group, mice immunized with radiation attenuated cercariae model in another attack on S. japonicum infection, "intercept" effect occurs mainly in the lung stage, anti-Schistosoma japonicum in the process, mice immunized with attenuated cercariae of lung dendritic cells and T cell activation was significantly higher than the normal infection control group , the removal of parasites play a key role.PartⅤStudy on the expression of T regulatory cells in BALB /c mice vaccinated with UV-attenuated Schistosoma japonicum cercariaeObjective To investigate the expressoion of CD4+CD25+Foxp3+T regulatory cells in peripheral blood, hepat-spleen tissues and its significance in BALB /c mice vaccinated with UV-attenuated Schistosoma japonicum cercariae.Methods The intraspleen and hepar expression of Foxp3 in UV-attenuated Schistosoma japonicum cercariae immunsed mice and the hepat-spleen tissues from normal cercariae infected mice as controls were analysed by immunohistochemical method and the frequency of CD4~+CD25~+Foxp3~+T cells derived from spleen and peripheral blood monocytes were detected from both groups of mice by flow cytometry.Results The expression of Foxp3 in the liver and spleen were much lower P <0. 05 than that in the control. The percentage of CD4~+CD25~+ Foxp3~+T cells both in spleen and the peripheral blood monocytes from UV-attenuated S. japonicum cercariae immused group was lower than that in control P <0. 05.Conclusion The increase expression of Foxp3 and degrade of intraspleen and liver CD4~+CD25~+Foxp3~+T regulatory cells has an important relationship with the UV-attenuated S. japonicum cercariae immused mice, the potential mechanisms of the UV-attenuated S. japonicum cercariae immused mice was it can reduce the S. japonicum excreting the inhibiting factor,and keep the stationary immune responses in the immused mice.Further investigation on the changesof frequency and function of the Treg cells would conduce to understand the mechanism of UV-attenuated S. japonicum cercariae’immunoprotection.In summary, this paper has successfully accomplished the investigations as follows:Ultraviolet radiation attenuated cercariae of Schistosoma japonicum in BALB/c mice mainly in the skin and the lungs were removed, and of "intercept" mainly in the lung .Transitional stage of lung schistosomula attenuated immune cells can induce a strong response. The immunized mice by the normal cercariae could induce higher immune protection against infection. Repeatedly irradiated cercariae attenuated by the passive transfer of immune serum in mice can induce higher immune protection, suggesting that the UV radiation attenuated cercariae induced immune protection mechanisms are also involved in humoral immune protection. Normal cercariae infection attacks the immunised mice infected with attenuated cercariae , in the mouse lung and spleen dendritic cells can induce the activation of more to mediate the late activation of T cells. Extend the observation time to infection after 6 weeks, 8 weeks, immunized mice liver and spleen CD4~+CD25~+Foxp3~+ T regulatory cells infected with the control group was higher than normal. The possible mechanism for the effect of UV radiation may destroy some of the normal secretion of inhibitory factor schistosome function, so that the immune response in a relatively stable state and not subject to the secretion of cytokines in schistosomiasis, the above characteristics and immunity induced by high radiation attenuated cercariae protective immune mechanism remains to be further studied. |
