Japonicum Egg Antigens Research Articles

Schistosome eggs stimulate reactive oxygen species production to enhance M2 macrophage differentiation and promote hepatic pathology in schistosomiasis.

Schistosomiasis is a neglected tropical disease of public health concern. The most devastating pathology in schistosomiasis japonica and mansoni is mainly attributed to the egg-induced granulomatous response and secondary fibrosis in host liver, which may lead to portal hypertension or even death of the host. Schistosome eggs induce M2 macrophages-rich granulomas and these M2 macrophages play critical roles in the maintenance of granuloma and subsequent fibrosis. Reactive oxygen species (ROS), which are highly produced by stimulated macrophages during infection and necessary for the differentiation of M2 macrophages, are massively distributed around deposited eggs in the liver. However, whether ROS are induced by schistosome eggs to subsequently promote M2 macrophage differentiation, and the possible underlying mechanisms as well, remain to be clarified during S. japonicum infection. Herein, we observed that extensive expression of ROS in the liver of S. japonicum-infected mice. Injection of ROS inhibitor in infected mice resulted in reduced hepatic granulomatous responses and fibrosis. Further investigations revealed that inhibition of ROS production in S. japonicum-infected mice reduces the differentiation of M2, accompanied by increased M1 macrophage differentiation. Finally, we proved that S. japonicum egg antigens (SEA) induce a high level of ROS production via both nicotinamide adenine dinucleotide phosphate (NADPH) oxidase 2 (NOX2) and mitochondria in macrophages. Our study may help to better understand the mechanism of schistosomiasis japonica-induced hepatic pathology and contribute to the development of potential therapeutic strategies by interfering with ROS production.

Xiaochaihu decorction relieves liver fibrosis caused by Schistosoma japonicum infection via the HSP47/TGF-\u03b2 pathway

BackgroundHepatic fibrosis caused by chronic infection with Schistosoma japonica remains a serious public health problem in the world. Symptoms include inflammation, liver granuloma and fibrosis, whilst treatment options are still limited. This study aims to investigate whether and how traditional Chinese medicine Xiaochaihu decoction (XCH) could mitigate liver fibrosis caused by S. japonicum infection.MethodsBALB/c mice were infected with S. japonicum cercariae and treated with XCH for 16 weeks. Liver pathological changes were assessed by H&E and Masson staining. NIH3T3 and Raw264.7 cells were treated with S. japonicum egg antigens with or without XCH treatment. Quantitative real-time PCR, western blot, immunfluorescence and ELISA were performed to determine the changes of levels of fibrogenic markers.ResultsXCH protected mouse liver from injuries and fibrosis caused by S. japonicum infection and considerably reduced egg burden in a dose-dependent manner. Infection with S. japonicum caused elevation of serum ALT, AST, ALP, HA and PIIINP levels and reduction of ALB and GLOB levels, which was markedly suppressed by XCH. The upregulation of TGF-β1, Hsp47, α-SMA, Col1A1 and Col3A1 in S. japonicum-infected mouse liver was also significantly inhibited by XCH. Schistosoma japonicum egg antigens promoted the expression of Hsp47, TGF-β1, Timp-1, α-SMA, Col1A1 and Col3A1 in NIH3T3 cells, and TGF-β1, CTGF, IL-13, IL-17 and IL-6 in Raw264.7 cells, which was inhibited by XCH, LY2157299 and shRNA-Hsp47.ConclusionsThese results demonstrated that the hepatic protective effects of Xiaochaihu decoction were mediated by HSP47/TGF-β axis.

RSjP40 suppresses hepatic stellate cell activation by promoting microRNA-155 expression and inhibiting STAT5 and FOXO3a expression.

Activation of hepatic stellate cells (HSCs) is the central event of the evolution of hepatic fibrosis. Schistosomiasis is one of the pathogenic factors which could induce hepatic fibrosis. Previous studies have shown that recombinant Schistosoma japonicum egg antigen P40 (rSjP40) can inhibit the activation and proliferation of HSCs. MicroRNA‐155 is one of the multifunctional noncoding RNA, which is involved in a series of important biological processes including cell development, proliferation, differentiation and apoptosis. Here, we try to observe the role of microRNA‐155 in rSjP40‐inhibited HSC activation and explore its potential mechanisms. We found that microRNA‐155 was raised in rSjP40‐treated HSCs, and further studies have shown that rSjP40 enhanced microRNA‐155 expression by inhibiting STAT5 transcription. Up‐regulated microRNA‐155 can down‐regulate the expression of FOXO3a and then participate in rSjP40‐inhibited expression of α‐smooth muscle actin (α‐SMA) and collagen I. Furthermore, we observed microRNA‐155 inhibitor could partially restore the down‐regulation of FOXO3a, α‐SMA and collagen I expression in LX‐2 cells induced by rSjP40. Therefore, our research provides further insight into the mechanism by which rSjP40 could inhibit HSC activation via miR‐155.

Egg antigen p40 of Schistosoma japonicum promotes senescence in activated hepatic stellate cells via SKP2/P27 signaling pathway

Schistosomiasis is characterized by egg deposition, granulomatous inflammatory reaction and then subsequent hepatic fibrosis formation. Activated HSCs are regarded as the main effector cells in the progression of liver fibrosis and induction of senescence in hepatic stellate cells (HSCs) is vital to the reversion of hepatic fibrosis. Our previous work has showed that S. japonicum egg antigen p40 (Sjp40) could promote HSCs senescence via a STAT3/p53/p21 mechanism. In this paper, the major aim was to explore whether there are other signaling pathways in the process of Sjp40-induced HSCs aging and the underlying effect of SKP2/P27 signal pathway in this procedure. We observed the Sjp40-induced decrease of α-SMA and the senescence of LX-2 cells, and Sjp40 could upregulate P27 and downregulate the protein level of SKP2. The senescence induced by Sjp40 might be reversed in LX-2 cells that treated with P27-specific siRNA or with SKP2-special over-expression plasmid. In addition, we also demonstrated that the decreased expression of P-Rb and α-SMA induced by Sjp40 were partly restored by SKP2-overexpression. These data suggest that Sjp40 might inhibit HSCs activation by promoting cellular senescence via SKP2/P27 signaling pathway, which put forward novel mechanism in the treatment of liver fibrosis.

Heat Shock Protein 60 in Eggs Specifically Induces Tregs and Reduces Liver Immunopathology in Mice with Schistosomiasis Japonica.

BackgroundParasitic helminths need to suppress the host immune system to establish chronic infections. Paradoxically, immunosuppression induced by the worm also benefits the host by limiting excessive inflammation and tissue damage, which remains the major cause leading to serious morbidity and mortality. Regulatory T cells (Tregs) are key immune regulators of this mutualism. The successive rise in Tregs during schistosome infection plays a critical role in immunoregulation. We and others previously showed that Schistosoma japonicum (S. japonicum) egg antigens (SEA) induce Tregs both in vitro and in vivo. In addition, we identified that SjHSP60 derived from SEA significantly induces Tregs in vivo and in vitro. However, the contribution of SjHSP60 in SEA to Treg induction and the related mechanisms of the Treg induction have not yet been identified.Methodology/Principal FindingsIn this study, we showed that S. japonicum stress protein HSP60 (SjHSP60) was constitutively and extensively expressed in eggs of S. japonicum. SjHSP60 specially induced Tregs in vivo and in vitro without inducing other CD4+ T sub-populations including Th1, Th2 and Th17 cells. Furthermore, we showed that the SjHSP60-depleted SEA almost lost the ability in vitro and displayed a significant impaired ability to induce Tregs in vivo. Finally, our study illustrated that the mechanisms of SjHSP60-mediated induction of Tregs are through both conversion of CD4+CD25- T cells into CD4+CD25+Foxp3+ Tregs and expansion of preexisting CD4+CD25+Foxp3+ Tregs in a TLR4-dependent manner.Conclusions/SignificanceCollectively, our findings identify SjHSP60 as a major parasitic contributor of Treg induction in S. japonicum egg antigens, which not only contributes to the better understanding of the mechanism of immunoregulation during helminth infection, but also suggests its potential as a therapeutic target for control of immunopathology, allergic and autoimmune diseases.

Protective immunity against Schistosoma japonicum infection can be provided by IgG antibodies towards periodate-sensitive or periodate-resistant glycans.

BackgroundIt has been well accepted that glycans present in schistosomes are highly antigenic. However, it is not clear what kind of worm glycans can affect the infected host to mount IgG responses and whether mounted anti-glycan IgG responses are protective.MethodsThe contribution of antigenicity by glycans was measured by using competitive ELISA assay in sera from infected mice and humans. Monoclonal antibodies towards soluble Schistosoma japonicum egg antigens (SjEA) were generated from SjEA immunizated mice. The expression of glycans on surfaces of cercaria or young worm and their distributions were examined by immunofluorescence assay. The protective roles of glycans-specific mAbs were assayed by determination of the worm and egg burden in infected mice.ResultsBoth periodate-resistant glycans and periodate-sensitive glycans are antigenic in schistosome infections. When monoclonal antibodies against either periodate-sensitive or periodate-resistant glycans were administered prior to schistosome infections in mice, both kinds of anti-glycan antibodies were found to successfully provide protective immunity to infected mice.ConclusionsBoth periodate-resistant and periodate-sensitive glycans are antigenic, and dominant anti-glycan IgG responses can play important roles in protective immunity in schistosome infected hosts.Electronic supplementary materialThe online version of this article (doi:10.1186/s13071-015-0842-1) contains supplementary material, which is available to authorized users.

Schistosoma japonicum egg antigen up-regulates fibrogenesis and inhibits proliferation in primary hepatic stellate cells in a concentration-dependent manner

To investigate the effects of different concentrations of Schistosoma japonicum (S. japonicum) egg antigen on fibrogenesis and apoptosis in primary hepatic stellate cells (HSCs). A mouse model of schistosomiasis-associated liver fibrosis (SSLF) was established by infecting mice with schistosomal cercaria via the abdomen. HSCs were isolated from SSLF mice by discontinuous density gradient centrifugation, and their identity was confirmed by immunofluorescence double staining of α-smooth muscle actin (α-SMA) and desmin. The growth inhibitory effect and 50% inhibitory concentration (IC50) of S. japonicum egg antigen for primary HSCs (24 h) were determined using a cell counting kit-8 (CCK-8) assay. The expression levels of α-SMA, matrix metalloproteinase-9 (MMOL/LP-9) and tissue inhibitor of metalloproteinases-1 (TIMP-1) in HSCs in response to different concentrations of S. japonicum egg antigen were detected by Western blotting and real-time reverse transcription-polymerase chain reaction. The levels of phospho-P38 (P-P38), phospho-Jun N-terminal kinase (P-JNK) and phospho-Akt (P-AKT) in HSCs were detected by Western blotting. An SSLF mouse model was established, and primary HSCs were successfully isolated and cultured. S. japonicum egg antigen inhibited HSC proliferation in a concentration-dependent manner. The IC50 of the S. japonicum egg antigen was 244.53 ± 35.26 μg/mL. S. japonicum egg antigen enhanced α-SMA expression at both the mRNA and protein levels and enhanced TIMP-1 expression at the mRNA level in HSCs (P < 0.05), whereas the expression of MMOL/LP-9 was attenuated at both the mRNA and protein levels in a concentration-dependent manner (P < 0.05). A high concentration of S. japonicum egg antigen enhanced P-P38, P-JNK and P-AKT activation (P < 0.05). The changes in α-SMA and MMOL/LP-9 expression induced by S. japonicum egg antigen were closely correlated with P-P38 and P-JNK activation (P < 0.05). The attenuation of MMOL/LP-9 was also correlated with P-AKT activation (P < 0.05), but the increase in α-SMA expression was not. TIMP-1 expression was not correlated with P-P38, P-JNK or P-AKT activation. S. japonicum egg antigen promotes fibrogenesis, activates the P38/JNK mitogen-activated protein kinase and AKT/PI3K signaling pathways and inhibits proliferation in primary HSCs isolated from SSLF mice in a concentration-dependent manner.

Comparison of Schistosoma mansoni Soluble Cercarial Antigens and Soluble Egg Antigens for Serodiagnosing Schistosome Infections

A Schistosoma mansoni cercarial antigen preparation (cercarial transformation fluid – SmCTF) was evaluated for detection of anti-schistosome antibodies in human sera in 4 collaborating laboratories. The performance of SmCTF was compared with that of S. mansoni egg antigens (SmSEA) in an indirect enzyme-immunoassay (ELISA) antigen assay, the latter being used routinely in 3 of the 4 participating laboratories to diagnose S. mansoni and S. haematobium infections. In the fourth laboratory the performance of SmCTF was compared with that of S. japonicum egg antigens (SjSEA) in ELISA for detection of anti-S. japonicum antibodies. In all 4 laboratories the results given by SmCTF in ELISA were very similar to those given by the antigen preparation routinely used in the respective laboratory to detect anti-schistosome antibodies in human infection sera. In so far as the ELISA results from SmCTF are thus so little different from those given by schistosome egg antigens and also cheaper to produce, the former is a potentially useful new diagnostic aid for schistosomiasis.

Dynamics of Th17 Cells and Their Role in Schistosoma japonicum Infection in C57BL/6 Mice

BackgroundThe current knowledge of immunological responses to schistosomiasis, a major tropical helminthic disease, is insufficient, and a better understanding of these responses would support vaccine development or therapies to control granuloma-associated immunopathology. CD4+ T cells play critical roles in both host immune responses against parasitic infection and immunopathology in schistosomiasis. The induction of T helper (Th)1, Th2 and T regulatory (Treg) cells and their roles in schistosome infections are well-illustrated. However, little in vivo data are available on the dynamics of Th17 cells, another important CD4+ T cell subset, after Schistosoma japonicum infection or whether these cells and their defining IL-17 cytokine mediate host protective responses early in infection.MethodologyLevels of Th17 and the other three CD4+ T cell subpopulations and the cytokines related to induction or repression of Th17 cell generation in different stages of S. japonicum infection were observed. Contrary to reported in vitro studies, our results showed that the Th17 cells were induced along with the Th1, Th2, Treg cells and the IFN-γ and IL-4 cytokines in S. japonicum infected mice. The results also suggested that S. japonicum egg antigens but not adult worm antigens preferentially induced Th17 cell generation. Furthermore, decreasing IL-17 with a neutralizing anti-IL-17 monoclonal antibody (mAb) increased schistosome-specific antibody levels and partial protection against S. japonicum infection in mice.ConclusionsOur study is the first to report the dynamics of Th17 cells during S. japonicum infection and indicate that Th17 cell differentiation results from the integrated impact of inducing and suppressive factors promoted by the parasite. Importantly, our findings suggest that lower IL-17 levels may result in favorable host protective responses. This study significantly contributes to the understanding of immunity to schistosomiasis and may aid in developing interventions to protect hosts from infection or restrain immunopathology.

Regulatory role of interleukin-10 and interferon-gamma in severe hepatic central and peripheral fibrosis in humans infected with Schistosoma japonicum.

Schistosoma japonicum is the most pathogenic agent of hepatosplenic schistosomiasis. It causes fibrosis of the central (CentF) and peripheral (PerF) portal areas. We investigated whether CentF and PerF in Chinese fishermen infected with S. japonicum were associated with an abnormal production of cytokines and chemokines that, in experimental models, have been implicated in the regulation of fibrosis. Cytokines were measured by enzyme-linked immunosorbent assay in cultures of peripheral blood mononuclear cells from 127 patients, after stimulation with S. japonicum egg antigens. Data were analyzed by logistic regression that included age, sex, number of treatment episodes, alcohol use, and exposure as covariates. CentF was associated with low levels of interleukin (IL)-10 (P= .0004), regulated on activation normally T cell expressed and secreted (P= .0004), and macrophage inflammatory protein-1alpha (P= .007). In a multivariate analysis, only IL-10 was associated with CentF (odds ratio [OR], 10.8; 95% confidence interval [CI], 3.2-38; P= .0004). Splenomegaly was also associated with low IL-10 production and, independently, with CentF. In multivariate analysis, PerF was associated with low production of interferon (IFN)-gamma (OR, 8.2; 95% CI, 2-33; P= .0035) but not with production of IL-10. IL-10 is associated with protection against central fibrosis, because of its anti-inflammatory and antifibrosis effects. IFN-gamma is associated with protection against PerF, which depends more on egg load and egg-associated toxicity.

Schistosoma japonicum egg antigens stimulate CD4+ CD25+ T cells and modulate airway inflammation in a murine model of asthma

A number of epidemiological and clinical studies have suggested an inverse association between allergy and helminth infection, such as Schistosomiasis. Therefore, we hypothesize that Schistosoma japonicum egg antigens, a type of native antigen, can induce production of CD4(+) CD25(+) T cells with regulatory activity, modulating airway inflammation and inhibiting asthma development. The frequency of CD4(+) CD25(+) T cells was determined by flow cytometry for mice treated with ovalbumin (OVA), CD25(+) depletion/OVA, schistosome egg antigens, schistosome egg antigens/OVA and for control mice. The ability of CD25(+) T cells from these mice to suppress T-cell proliferation and cytokine production was investigated both in vivo and in vitro. Results showed that the CD4(+) CD25(+) T cells of OVA-treated mice exhibited impaired control of dysregulated mucosal T helper 2 responses compared to the controls (P < 0.05). Depletion of CD25(+) cells accelerated OVA-induced airway inflammation and increased the expression of interleukin (IL)-5 and IL-4. Treatment with schistosome egg antigens increased the number and suppressive activity of CD4(+) CD25(+) T cells, which made IL-10, but little IL-4. In a murine model of asthma, S. japonicum egg antigens decreased the expression of Th2 cytokines, relieved antigen-induced airway inflammation, and inhibited asthma development. Thus, we provided evidence that S. japonicum egg antigens induced the production of CD4(+) CD25(+) T cells, resulting in constitutive immunosuppressive activity and inhibition of asthma development. These results reveal a novel form of protection against asthma and suggest a mechanistic explanation for the protective effect of helminth infection on the development of allergy.

Characterization of CD4&amp;lt;sup&amp;gt;+&amp;lt;/sup&amp;gt; T Cell Responses in Mice Infected with &amp;lt;italic&amp;gt;Schistosoma japonicum&amp;lt;/italic&amp;gt;

To better understand the interaction between Schistosoma japonicum and its murine host, we characterized the immune response of CD4+ T cells generated during an experimental S. japonicum infection based on different key aspects, from gene expression to cell behavior. Mouse oligonucleotide microarrays were used to compare gene expression profiles of CD4+ T cells from spleens of mice at 0, 3, 6 and 13 weeks post-infection. Flow cytometry analysis was used to determine type 1 and type 2 cytokine-secreting CD4+ T cells, to test apoptosis of CD4+ T cells and to count CD4+CD25+ T cells, a kind of regulatory subpopulation of CD4+ T cells. The percentage of interleukin-4-producing CD4+ T cells was found to be much higher than that of gamma-interferon-producing cells, especially after stimulation with S. japonicum egg antigen, which was consistent with type 1 and type 2 cytokine gene expression in the genechip. Microarray data also showed that S. japonicum induced the increased expression of Th2 response-related genes, whereas some transcripts related to the Th1 responsive pathway were depressed. Flow cytometry analysis showed a marked increase in the apoptotic CD4+ T cells from 6 weeks post-infection and in the ratio of CD4+CD25+ to CD4+ T cells in infected mice after 13 weeks. We therefore concluded that experimental infection of mice with S. japonicum resulted in a Th2-skewed immune response, which was to a great extent monitored by the immune regulatory network, including cytokine cross-modulation, cell apoptosis and the subpopulation of regulatory cells.

Serodiagnosis of Schistosoma mansoni infections in an endemic area of Burkina Faso: performance of several immunological tests with different parasite antigens

The performance of indirect haemagglutination assays (IHA), enzyme-linked immunosorbent assays (ELISA) and indirect immunofluorescent antibody tests (IFAT) were compared with 450 sera from a Schistosoma mansoni-endemic area in Burkina Faso. All participants in this survey provided at least one sample each of stool, urine and serum. From those with an egg-negative Kato–Katz thick smear, a second stool sample was examined. IHA was based on either extracts of adult S. mansoni worms (SmIHA) or S. japonicum egg antigen (SjIHA). For ELISA, three antigen preparations were used, namely: (i) soluble S. mansoni adult worm antigens (SWAP); (ii) soluble S. mansoni egg antigens (SEA); and (iii) a cationic exchange fraction of S. mansoni eggs (CEF6). IFAT was performed with S. mansoni male worm sections. Among the egg-excretors, the sensitivity of ELISA was high and egg antigens performed slightly better (SEA, 96%; CEF6, 97%) than worm antigen (94%). Sensitivity of IHA was satisfactory with homologous (Sm, >85%), but not heterologous (Sj, 56%) parasite antigen. In IFAT, the parenchyma-associated fluorescence showed high sensitivity (95%), but gut-associated fluorescence, which is known to be a sensitive diagnostic marker for schistosome-infected European travelers, was observed only in 76% of a sub-sample of 100 of the endemic sera. Among sera from egg-negative individuals, many gave positive reactions in several or all of the tests employed. These reactions (formally “false positive”) are considered to represent true infections, since chemotherapy had not yet been delivered to this population. For the purpose of further surveys in Burkina Faso or other resource-poor settings, we suggest IHA as an accurate diagnostic test and propose to further improve its performance by including egg rather than worm antigens.

Characterization of Schistosoma japonicum specific egg antigen recognized by circumoval precipitin (COP) producing monoclonal antibodies

In order to analyze the antigens concerned with circumoval precipitin (COP) reactions, four monoclonal antibodies (18-4-1, 56-8-38, 85-16-1, 48-39-2) were obtained from spleen cells of mice infected with Schistosoma japonicum. All four gave positive COP reactions against S. japonicum eggs. All except 18-4-1, however, also reacted with S. mansoni eggs. Monoclonal antibodies 18-4-1 and 48-39-2 reacted specifically with schistosome egg antigens but not with antigens derived from adult schistosomes and 10 other species of helminths in enzyme-linked immunosorbent assay (ELISA), suggesting that these antibodies have high specificity and would be useful for characterization of the antigens concerned with COP reactions. The egg antigens recognized by antibodies 18-4-1 and 48-39-2 were identified by immunoblotting. Antibody 18-4-1 reacted only with S. japonicum egg antigens of mol. wt. 330 and 360 kDa, while 48-39-2 reacted with S. japonicum egg antigens of mol. wt. ranging from 58 to 265 kDa and with S. mansoni egg antigens of mol. wt. 62 kDa. The epitope recognized by 18-4-1 can be regarded as carbohydrate and peptide, whereas that recognized by 48-39-2 appears to be only carbohydrate. The COP antigens characterized by antibodies 18-4-1 and 48-39-2 have not been identified so far, on the grounds of differences in their specificity and molecular weight from those in previous reports.

Comparison of immune repertoires of Chinese and Philippine patients infected with Schistosoma japonicum

Chinese and Philippine patients exhibited detectable titers of serum antibodies to Schistosoma japonicum worm and egg antigens. Western blot (immunoblot) data revealed differing antigenic profiles. Antigen inhibition studies showed low and high levels of cross-reactivity with anti-worm and anti-egg antibodies, respectively, derived from both Chinese and Philippine patients. Thus, anti-egg antibodies and egg antigens are more conserved than anti-worm antibodies and worm antigens.

Reactivity ofSchistosoma japonicumandS. mansoniantigen preparations in indirect haemagglutination (IHA) with sera of patients with homologous and heterologous schistosomiasis

Sera of patients infected with Schistosoma japonicum, S. mansoni or S. haematobium were tested in an indirect haemagglutination assay (IHA) using soluble S. japonicum egg antigen (SjSEA) and soluble S. mansoni adult antigen prepared either from a Puerto Rican strain (SmAWA) or an Egyptian strain (SmBW; Cellognost-Schistosomiasis Kit). Reactions were best, in terms of titres and sensitivity, in homologous systems. Heterologous systems were less reliable, particularly those using sera from urinary schistosomiasis patients. It is suggested that IHA is a suitable test to detect Schistosoma infections, especially when homologous systems are used.

Regulation of the human T-cell response toSchistosoma japonicum egg antigen by concomitant cellular and humoral mechanisms in vitro

Serum-mediated regulation of T-cell responses specific for soluble egg antigen (SEA) of Schistosoma japonicum was tested in human hosts. When we added autologous serum to SEA-specific human T-cell lines (CD3+, 4+, 8-), we observed suppression of T-cell proliferation, and this suppressive activity was detected in the immunoglobulin-G2 (IgG2) subclass. Suppression was dose-dependent and antigen-specific. T-cell proliferation induced by only one SEA fraction of greater than 18 kDa was modulated in the presence of 100 micrograms/ml autologous as well as allogeneic infected IgG2. This SEA fraction-driven proliferation was also regulated by suppressor T-cells through distinct suppressive mechanisms. Our results suggest that T-cell responses to a particular component(s) of SEA are strictly regulated through both cellular and humoral mechanisms in human chronic S. japonicum infection.

Generation and functional characterization of T cell lines and clones specific for Schistosoma japonicum egg antigen in humans.

T cell lines specific for Schistosoma japonicum egg Ag were established in vitro from patients with chronic schistosomiasis japonica, and investigated their possible immunopathologic roles by testing lymphokines production and in vitro granuloma formation assay. All lines tested had surface phenotypes of CD3+ CD4+ CD8-, and showed S. japonicum soluble egg Ag (SEA)-specific proliferation requiring HLA-DR-restricted Ag presentation. Of these fractions of SEA separated by gel filtration, Fraction II (m.w. 7,000 to 18,000) and III (m.w. 7,000) induced strong proliferation of T cell lines, whereas fraction I (m.w. 18,000+) failed to induce detectable proliferation to any T cell lines tested. One of the T cell lines was cloned by micromanipulation: two of eight clones responded only to fraction II, and six to both fractions II and III. We observed that four of eight clones tested produced IL-2 in response to SEA, and three of them were able to transfer S. japonicum egg-specific granulomatous hypersensitivity in vitro to an HLA haplo-identical individual without previous schistosome infection. These immunopathologic functions of T cell clones seemed to be activated by at least two distinct epitopes of SEA. Our present observations suggest that at least two distinct CD4+ human T cells, both of which recognize epitopes expressed on SEA molecules of less than 18 kDa, might have critical roles in granulomatous hypersensitivity to eggs of S. japonicum in humans.

Schistosoma japonicum egg antigen-specific T cell lines in man. Induction of helper and suppressor T cell lines and clones in vitro in a patient with chronic schistosomiasis japonica.

T cell lines (TCLs) specific for Schistosoma japonicum egg antigen were established from a patient with chronic schistosomiasis japonica to investigate the regulatory mechanism of S.japonicum egg antigen-driven T cell responses in man. All five TCLs tested were CD2+, CD4+, CD8-, and were strongly proliferative only to S. japonicum egg antigen in the absence of exogenous IL-2. All but one TCL produced IL-2-like lymphokines in vitro, indicating their helper T cell functions. One TCL, SjE-3, failed to produce IL-2-like lymphokines. Moreover, this TCL suppressed the specific proliferation of autologous peripheral blood lymphocytes to S. japonicum egg antigen. This TCL produced a soluble suppressor factor(s). These functional diversities among established TCLs were also confirmed by cloned T cells. Our observations might suggest that the regulatory system through helper and suppressor T-T interactions somehow involved in T cell responses to the egg antigen in human chronic schistosomiasis japonica.

Modulation of Schistosoma japonicum pulmonary egg granulomas with monoclonal antibodies.

We have examined the ability of various Schistosoma japonicum egg antigens to sensitize mice for subsequent secondary pulmonary egg granuloma formation. Further, we produced monoclonal antibodies (Mabs) specific for egg antigens and evaluated their abilities to modulate pulmonary granuloma formation and inhibit soluble egg antigen (SEA)-stimulated lymphocyte blastogenesis. A homogeneous, 140 Kd egg glycoprotein, SJe; 140-GP was nearly as effective as intact eggs in sensitizing for egg-focused pulmonary granuloma formation, while SEA, or the heterogeneous immunoaffinity (IA)-purified C10 antigens were ineffective. The in vivo administration of chronic infection serum (CIS) or Mabs reactive with SJe; 140-GP, to egg-sensitized/egg-challenged mice, modulated pulmonary granuloma formation. Two of these modulatory SJe; 140-GP-specific Mabs (1 A1-1 or 14B3-8), an IgG1, and an IgG3, respectively, did not alter the responses of SEA-stimulated lymph node cells from mice with acute or chronic schistosomiasis japonica. In contrast, another SJe; 140-GP-specific IgG3 Mab (7A6-5), CIS, immunoaffinity purified anti-SEA from CIS, or the non-SEA-binding fraction of CIS, all resulted in dose-related inhibition of SEA-induced proliferation. These data confirm the antibody-driven nature of some immunoregulatory networks in murine schistosomiasis japonica, and extend these observations to include certain Mabs. The immunogenic nature of SJe; 140-GP, and the modulatory and inhibitory activities of Mabs specific for this glycoprotein, indicate it may play a central role in granuloma formation and modulation in this infection.