环孢素A体外抗AF18标记的曼氏血吸虫童虫的研究

目的　探讨环孢素A体外抗AF18标记的曼氏血吸虫童虫的作用以及虫体表膜流动性。　方法　制备童虫,环孢素A体外作用,AF18标记,荧光显微镜观察。　结果　童虫损伤或死亡,虫体逐渐从绿色变成黄色,虫体表面损伤。　结论　环孢素A增加童虫AF18的含量,减低童虫表膜流动性。     

环孢素A体外抗AF18标记的曼氏血吸虫童虫的作用

目的探讨环孢素A抗曼氏血吸虫童虫的作用机制。方法制备童虫,环孢素A体外作用,AF18标记,荧光显微镜观察;定量童虫荧光素的分布以及测定光漂洗后童虫荧光素的复原率。结果童虫损伤或死亡,虫体逐渐从绿色变成黄色,虫体表面损伤;随着环孢素A剂量加大,童虫荧光素定量增加;童虫光漂洗后荧光素的复原率大幅度降低。结论环孢素A增加童虫AF18的含量,降低童虫荧光素的复原率,减低童虫表膜流动性;提示,表膜是药物作用的靶标。     

环孢素A体外抗FITC-ConA标记的曼氏血吸虫童虫的作用

目的 探讨环孢素A体外抗FITC—ConA标记的曼氏血吸虫童虫的作用以及虫体表膜通透性。方法 人工制备曼氏血吸虫童虫，使用FITC—ConA进行标记，环孢素A体外作用，荧光显微镜下观察并摄照。结果 童虫损伤或死亡，虫体逐渐从淡蓝色变成亮蓝色，虫体可见多个亮蓝色小点，虫体表面损伤。结论 环孢素A能增加童虫表膜流动性。     

环孢素A对体外培养的曼氏血吸虫雌虫超微结构的影响

ＭＦ１小鼠人工感染曼氏血吸虫六周后，经主动脉和门静脉灌注收虫。雌虫暴露在含有不同剂量环抱素Ａ的１９９培养液中体外培养。２４小时后，经药物作用后的虫体分别作扫描电镜和透射电镜观察。雌虫体表嵴结构肿胀；外皮层基质出现空泡；卵黄细胞崩解、卵黄球减少；肠上皮细胞破坏，微绒毛缺损。本结果表明，环孢素Ａ对曼氏血吸虫雌虫具有直接作用，虫体外皮层、卵黄细胞和肠上皮似乎是药物攻击的靶结构。     

环孢素A体外抗曼氏血吸虫作用的观察

ＭＦ１小鼠实验感染曼氏血吸虫尾蚴１周、３周和６周后，分别经肺静脉和门静脉灌注取虫。实验显示，药物体外抗曼氏血吸虫的作用呈时间、剂量和虫龄依赖方式，童虫和雄虫对药物更敏感。     

环孢素A体外抗曼氏血吸虫雄虫的时间生物学研究

目的：探讨环孢素Ａ体外抗曼氏血吸虫的作用。方法：ＭＦ１小鼠实验感染曼氏血吸虫６ｗｋ后，经主动脉和门静脉灌注收虫。将雄虫放入含有１μｇ／ｍｌ、１０μｇ／ｍｌ、１５μｇ／ｍｌ、２０μｇ／ｍｌ和２５μｇ／ｍｌ环孢素Ａ的１９９培养液中体外培养。用扫描电镜对药物所致的虫体皮层损害作时间生物学观察。结果：在体外，雄虫经１μｇ／ｍｌ环孢素Ａ作用后，体嵴的结构疏松；经１０μｇ／ｍｌ环孢素Ａ作用２４ｈ后，雄虫皮层肿胀；雄虫经１５μｇ／ｍｌ环孢素Ａ作用８ｈ－２４ｈ后，虫体皮层破溃；虫体经２０μｇ／ｍｌ药物作用２４ｈ后，雄虫皮层明显破溃；雄虫经２５μｇ／ｍｌ环孢素Ａ作用８ｈ后，皮层褶嵴受损；作用１６ｈ后，皮层肿胀；作用２４ｈ后，皮层极度破溃，皮棘脱落。药物所致的虫体皮层损害与剂量和时间呈依赖关系。结论：环孢素Ａ具有直接杀曼氏血吸虫的作用。     

环孢素A体外抗曼氏血吸虫合胞体超微结构的变化

[目的 ]探讨环孢素A体外抗曼氏血吸虫超微病理改变。 [方法 ]MF1小鼠实验感染曼氏血吸虫 6wk后 ,经主动脉和门静脉灌注收集虫体。将虫体放入含有 2 0 μg/ml环孢素A的M199培养液中体外培养。用扫描电镜和透射电镜观察药物所致的虫体损害。 [结果 ]药物作用后 ,大多数雄虫皮层肿胀、表面出现大小不一的结节、皮层外膜破溃、皮棘脱落、合胞体极度破坏 ;个别雄虫皮层出现空泡 ;雌虫皮层极度空泡变及合胞体受损。 [结论 ]环孢素A具有直接抗曼氏血吸虫的作用 ,合胞体受损是药物作用的主要机制。     

人源性抗日本血吸虫肌球蛋白Fab噬菌体抗体体外杀童虫作用

目的观察人源性抗日本血吸虫肌球蛋白Fab噬菌体抗体体外杀伤血吸虫童虫作用。方法利用日本血吸虫肌球蛋白(Sj myosin)对人源性抗日本血吸虫Fab噬菌体抗体库进行富集筛选,获得抗Sjmyosin的特异性噬菌体抗体,将该抗体和巨噬细胞或补体与日本血吸虫童虫共培养,测定体外杀伤日本血吸虫童虫作用。结果将抗Sj myosin噬菌体抗体和巨噬细胞及补体与血吸虫童虫共培养时,在培养后24h即出现杀伤作用(童虫死亡率为4.69%),48h童虫死亡率达84.06%,96h童虫死亡率达89.38%。结论人源性抗Sj myosin Fab噬菌体抗体具有体外杀伤日本血吸虫童虫活性。     

环孢菌素A体外抗曼氏血吸虫的透射电镜观察

ＭＦ１小鼠实验感染曼氏血吸虫６ｗｋ后，经主动脉和门静脉灌注收虫。虫体暴露在含有２５μｇ／ｍｌ环孢菌Ａ的１９９型培养液中体外培养。药物所致的虫体损害作透射电镜观察。结果表明，雄虫较雌虫体外对环孢菌素Ａ更敏感，药物作用８ｈ后，雌虫皮质基层有空泡形成；药物作用１６ｈ后，雌虫外质膜破溃、皮棘松动；药物作用２４ｈ后，雌虫实质中有空泡形成、卵黄腺细胞破坏、卵黄小滴减少，雄虫基质有巨大空泡形成、皮棘缺损。结果显     

日本血吸虫与曼氏血吸虫的致病差异

曼氏血吸虫和日本血吸虫是全球范围内两种主要的肠道血吸虫病病原体,所致基本病理均为虫卵引起的肝脏肉芽肿和纤维化,但两者在产卵方式以及肉芽肿的组成细胞等方面均存在明显差异。 目前,我国的血吸虫病研究主要以日本血吸虫病为对象,国外主要以曼氏血吸虫病为对象,而介绍两种血吸虫致病差异的综述较少。 为更好地理解两种血吸虫的致病差异,本文从血吸虫的基因组和进化路径、幼虫迁移、成虫寄生位置及产卵方式、局部组织病理、肉芽肿的形成机制以及肉芽肿的细胞组成等 6 个方面对日本血吸虫和曼氏血吸虫的致病差异进行了综述。     

Suppression of macrophage-mediated antibody-dependent killing of Schistosoma mansoni larvae by concanavalin A stimulated spleen cell-derived factor(s)

Culture supernatants (sup) from rat spleen cells stimulated with concanavalin A (Con A) sepharose 4B suppressed schistosomulum killing by macrophages in a system of antibody-dependent cell-mediated cytotoxicity (ADCC). (a) The suppressive effect of the sup was strongest when they were added to cultures at the start of the ADCC assay, and it was decreased when sup were added to cultures in which the ADCC assay had begun more than 3 h previously. (b) From the results of various experiments in ADCC reaction, it was suggested that the suppressive factor(s) inhibited at least in part the interaction between macrophages and antibodies which had been bound to schistosomula, and that the suppressive factor(s) was bound to the macrophage side. (c) The suppressive activity was partially inactivated by treatment at 56 degrees C for 30 min, and it was lost almost completely by the treatment at 100 degrees C for 10 min. (d) The suppressive factor(s) differed from known cytokines such as interleukin 1 (IL-1), interleukin 2 (IL-2), granulocyte-macrophage-colony stimulating factor (GM-CSF), interferon-gamma (IFN-gamma), and tumour necrosis factor (TNF).     

In vivo expression of cytokine mRNA in rats infected with Schistosoma mansoni

As an animal model, rat schistosomiasis mansoni has provided considerable knowledge of immune mechanisms involved in the expulsion of worms and in a subsequent development of immunity to reinfection. Although it is clear that ADCC mechanisms participate in immunity to reinfection; the nature of the cytokines involved in immunity is unknown. To analyse the pattern of cytokines involved, the mRNA levels of different cytokines were assessed by RT-PCR as they occur within tissues during the course of infection. In spleens from infected rats, a significant elevation in IL-2 and IL-5 mRNA was observed during the early phase of infection (day 7). Analysis of pulmonary cytokine responses showed a dramatic increase in IL-4 and IL-5 on day 7. This was accompanied with a low but significant increase in IL-2 (day 11) and IL-12 (day 7) in the absence of augmented IFN-γ expression. The cytokine expression patterns of draining lymph nodes (LN) from infected rats showed a significant increase of IL-2, IL-4 and IL-5 on day 21. Analysis of IL-10 expression showed exclusively a significant increase in LN on day 11. IFN-γ mRNA was not detected in any tissue sample. Thus, rats develop a predominately Th2-type cytokine response during a primary infection which may be involved at least in part, in the expression of immunity against Schistosoma mansoni infection .     

Clinical investigation of a population recently infected with Schistosoma mansoni (Richard-Toll, Senegal)

Following the introduction of large-scale irrigation, an exceptional epidemic of intestinal schistosomiasis occurred in northern Senegal when a non-immune population was exposed to massive infection. Subjects infected with Schistosoma mansoni were followed up parasitologically and clinically from the onset of the epidemic. After the initial evaluation, patients received a health education session and were treated with praziquantel in a dose of 30 mg/kg. One year after this treatment, S. mansoni eggs were found in the stools of 227/301 subjects (75%). Twenty-three per cent of subjects excreted >400 eggs per gram (e.p.g.) and 11% excreted >1000 e.p.g. of faeces. Overall, the geometric mean was 191 e.p.g. of faeces in infected individuals. The prevalence of diarrhoea was reduced from 55 to 29%, the prevalence of bloody diarrhoea from 44 to 11% and the prevalence of abdominal discomfort from 66 to 41%. No hepatomegaly was found in these patients either before or one year after treatment. Splenomegaly was reduced from 30% (measured by ultrasound) to 3% (on clinical examination). Morbidity associated with S. mansoni infection was considerably reduced one year after treatment with praziquantel (30 mg/kg).     

Antibody-independent binding and activation of complement by Schistosoma mansoni adult worms

The in vitro binding serum complement (C) components to Schistosoma mansoni worms was studied. By exposing frozen sections of adult male and female parasites to normal human serum, binding of both classical and alternative pathway C components was observed. By immunofluorescence (IFL) microscopy selective binding of Clq, C4 and C3 to the schistosomal tegument, internal structures, the intestinal tract and eggs was seen. The C4 and C3 binding was completely abolished in the presence of 10 mM EDTA. EGTA also completely inhibited binding of C4 and most of the C3 binding. These results suggest that C binding to S. mansoni adult worms occurs mostly by the classical activation pathway. However, the partial Ca2+ independence of C3 binding and the demonstrated binding of the regulatory protein beta 1H suggests that worms are capable also of C3 binding by the alternative pathway. No C binding occurred to intact worms. Although some in vivo bound immunoglobulin appeared to be present occasionally at the parasite surface and in the gut, this material did not account for the demonstrated extensive C deposition upon incubation of frozen sections with normal human serum in vitro. Antibody independence of the observed classical pathway C binding was further indicated by binding of isolated Clq to the same structures capable of binding C components from serum.     

Eosinophilic interleukin 5 (IL-5) transgenic mice: eosinophil activity and impaired clearance of Schistosoma mansoni

Eosinophilia is a feature common to many invasive helminth infections and eosinophils are often considered to be effector cells in immunity to helminths. This study examined the possible influence of constituitive eosinophilia on the clearance of Schistosoma mansoni infections in mice. Eosinophils from interleukin-5 transgenic mice exhibit normal ultrastructure and function with regard to phagocytosis and killing of bacteria and responses to chemotactic stimuli. IL-5 transgenics and non-transgenic littermates were immunized once or four (hyperimmunization) times with irradiated cercariae of S. mansoni . Animals were challenged percutaneously with unirradiated cercariae one month after their last exposure to irradiated parasites. One month after challenge transgenic animals, whether unimmunized, vaccinated or hypervaccinated, carried significantly more liver-stage parasites than non-transgenic animals. These results suggest that although eosinophils from IL-5 transgenic mice are functional for a number of key parameters, large numbers of eosinophils and/or high levels of IL-5 may in some way impair clearance of S. mansoni. A re-evaluation of the roles of eosinophils and IL-5 in infections with this and other parasites may therefore be warranted .     

The Th1 to Th2 shift induced by Schistosoma mansoni does not exacerbate murine aids (MAIDS)

Schistosoma mansoni infection in mice is associated with a switch from a Th1 to a Th2-type cytokine response. The role of Th1 and Th2 responses in immune dysregulations associated with AIDS and murine AIDS (MAIDS) is controversial, but a Th2 bias could be associated with disease progression, raising the hypothesis that helminth infections might accelerate the retroviral disease progression. Here, we used the murine model of AIDS to evaluate the course of the viral disease during co-infection with S. mansoni . C57BL/6 mice were infected with S. mansoni cercariae 8 weeks before intravenous challenge with the LP-BM5 retroviral complex. MAIDS did not progress faster in co-infected mice, in terms of spleen and inguinal lymphadenopathy size, ecotropic virus titres in the spleen, or in vitro proliferative responses to mitogen. Th2 cytokine production was not enhanced in co-infected animals, except for an isolated increase in IL-4 production 21 weeks after LP-BM5 infection. Co-infected animals had significantly lower lymph node and spleen weights than mice infected with LP-BM5 only. MAIDS did not influence the granulomatous response to S. mansoni in the liver of co-infected mice. Finally, infection with S. mansoni neither enhanced Th2 cytokine production nor accelerated MAIDS progression in animals subsequently challenged with LP-BM5 .