[Recombinant expression of Schistosoma japonicum fructose-1, 6-bisphos- phate aldolase and its expression in different developmental stages of S. japonicum].

OBJECTIVE: To clone, express and purify Schistosoma japonicum fructose-1, 6-bisphosphate aldolase (SjFBPA) in E. coli and observe its expression in different developmental stages of S. japonicum. METHODS: FBPA gene was amplified from S. japonicum adult worm cDNA by using PCR. The amplified product was recombined into pET28a plasmid, and inducibly expressed with IPTG in E. coli BL21. SDS-PAGE and Western blotting were employed to analyze and identify the recombinant protein SjFBPA (rSjFBPA). Then, rSjFBPA was purified by chromatographic purification and its purity was analyzed by SDS- PAGE. The protein concentration of rSjFBPA purified was measured by the BCA method. Furthermore, SjFBPA mRNA was ana- lyzed in different developmental stages of S. japonicum by RT-PCR. RESULTS: SjFBPA was successfully amplified by using PCR and identified by restriction enzyme digestion and sequencing. The Western blotting analysis confirmed that the recombinant pro- tein could specifically reactive to the anti-His-tag monoclonal antibody. The concentration of the purified recombinant protein was about 4 mg/ml. The result of RT-PCR showed that SjFBPA mRNA was expressed in cercaria, schistosomulum, adult worm and egg of S. japonicum. CONCLUSION: SjFBPA is successfully recombined and expressed in a prokaryotic system, and SjFBPA mRNA is expressed in cercaria, schistosomulum, adult worm and egg of S. japonicum.

Schwann cells induce Proliferation and Migration of Oligodendrocyte Precursor Cells Through Secretion of PDGF-AA and FGF-2.

Our previous study has showed that co-grafted Schwann cells (SCs) promote proliferation and migration of the grafted oligodendrocyte precursor cells (OPCs). However, how the co-grafted SCs affect OPCs has not been clarified. In the present study, we confirmed that SC-induced proliferation and migration of OPCs were mediated by SC-secreted factors using SC-conditioned medium (SCM). Then, we detected several candidate factors, PDGF-AA, FGF-2, and IGF-1, in SCs and SCM, and their receptors in OPCs. Finally, by using the selective inhibitors, the effects of these candidate factors on proliferation and migration of OPCs were examined. Our results showed that SCM-stimulated proliferation and migration of OPCs could be markedly decreased by both AG1295 (the inhibitor of PDGFR) and PD173074 (the inhibitor of FGFR). Together, our study suggests that SCs affect proliferation and migration of OPCs through secreting PDGF-AA and FGF-2. Identity of these molecules not only contributes to understand the mechanism of SC-induced proliferation and migration of OPCs but also provides possible target for treatment of CNS diseases.

Level of hepatitis B surface antigen might serve as a new marker to predict hepatocellular carcinoma recurrence following curative resection in patients with low viral load.

To investigate the association between preoperative HBsAg (hepatitis B surface antigen) level and risk of HCC (hepatocellular carcinoma) recurrence following curative resection, we enrolled 826 HBV-related HCC patients who underwent curative resection and received long-term follow-up at the Eastern Hepatobiliary Surgery Hospital (Shanghai, China). Multivariate analyses showed that serum HBsAg ≥ 2000 S/CO, seropositive hepatitis B e antigen (HBeAg), γ-glutamyl transpeptidase > 61 U/L, prothrombin time > 13 s, multinodularity, lager tumor size, and major portal vein invasion were independently associated with a increased risk of HCC recurrence. Compared with HCC patients with HBsAg level < 2000 S/CO, HCC patients with HBsAg level ≥ 2000 S/CO had a higher prevalence of seropositive HBeAg, antiviral therapy, and cirrhosis; were younger; and had a higher levels of alanine transaminase (ALT), aspartate aminotransferase (AST), and HBV viral load. Multivariable stratified analyses showed HCC patients with HBsAg level < 2000 S/CO tended to have a lower incidence of HCC recurrence in following subgroups of patients, including for noncirrhotic (HR, 0.561; 95% CI, 0.345-0.914), HBV DNA < 2000 IU/mL (HR, 0.604; 95% CI, 0.401-0.912), ALT ≤ 41 U/L (HR, 0.643; 95% CI, 0.440-0.942), AST ≤ 37 U/L (HR, 0.672; 95% CI, 0.459-0.983), and seronegative HBeAg (HR, 0.682; 95% CI, 0.486-0.958). When we evaluated HBeAg-negative patients with HBV DNA < 2000 IU/mL, HBsAg level still determined risk of HCC recurrence (p = 0.014), but not HBV DNA (p = 0.550) and ALT (p = 0.186). These results suggest high levels of HBsAg increase risk of HCC recurrence following curative resection. HBsAg level might serve as a new marker to complement HBV DNA level in predicting HCC recurrence, especially in HBeAg-negative patients with low viral load.

Tim-2 up-regulation and galectin-9-Tim-3 pathway activation in Th2-biased response in Schistosoma japonicum infection in mice.

T cell immunoglobulin domain and mucin domain (Tim) family, a new gene that expresses on the surface of T cells, plays a critical role in regulation of T cells response. Previous data have shown that Tim-3 expressed on Th1 cells promotes itself apoptosis. Tim-2 is preferentially up-regulated during Th2 differentiation and functions as a potent costimulatory molecule for T-cell immunity. The present study aims to learn whether Tims are responsible for Th2-biased response evoked by Schistosoma japonicum infection. The expressions of Tim-2 and Tim-3 in spleen lymphocytes from S. japonicum-infected mice were examined, and the possible role of galectin-9-Tim-3 pathway in Th2-biased response triggered by schistosome infection was discussed. Our results showed that Tim-2 mRNAs were up-regulated in the spleen of schistosome-infected mice, which coincided with elevated IL-4 gene expression. Administration of galectin-9 significantly induced apoptosis of naïve spleen lymphocytes with down-regulation IFN-γexpression in vitro. Additionally, Tim-3-Fc fusion protein notably enhanced Th1 cells and decreased Th2 cells in vitro. Thus, we concluded that pro-apoptotic effects on Th1 population through galectin-9-Tim-3 pathway and the up-regulation of Tim-2 on Th2 cells might be critical to Th2-biased response of host with schistosomiasis japonica.

Evaluation of recombinant SjLAP and SjFBPA in detecting antibodies to Schistosoma japonicum.

OBJECTIVE: To investigate the early response of immunoglobulin G (IgG) antibody responses to Schistosoma japonicum infection in mice by using the recombinant proteins, S. japonicum leucine aminopeptidase (rSjLAP) and S. japonicum fructose-1, 6-bisphosphate aldolase (rSjFBPA), and evaluate the potential of rSjLAP and rSjFBPA in diagnosis as well as in assessment of therapeutic efficacy in human schistosomiasis. METHODS: rSjLAP or rSjFBPA was induced from Escherichia coli BL21 strain transfected with the expression vectors, pET-28a-rSjFBPA/BL21 or pET-28a-rSjLAP/BL21 using isopropyl-beta-D-thiogalactoside (IPTG), and purified by Ni-NTA His Bind resin. 88 BALB/c female mice, inbred and 6 to 8 weeks old, were randomly divided into 4 groups. Groups A, B and C each made up of 21 mice and group D comprised 25 mice. Groups A, B and C were infected with 5, 15 and 25 S. japonicum cercariae respectively. As control, mice in group D were left uninfected. 3 mice from each of groups A, B and C were sacrificed and sera collected on days 3, 7, 10, 14, 20, 30, and 60 post infection. All the 25 mice in group D were sacrificed on the first day of the experiment for serum collection. rSjLAP and rSjFBPA were screened and used in ELISA to test the antibody response of the serum samples. Also, sera of 38 acute patients, 96 chronic patients with schistosomiasis japonica, 90 healthy donors and patients with other parasite infections including Clonorchis sinensis (33 cases), Paragonimus westermani (40) and hookworms (37) were tested using the recombinant protein-based ELISA. In addition, 36 sera each from the acute and chronic patients 12 months after treatment with praziquantel and 64 of the chronic patients in more than 2 years post-treatment of praziquantel were tested. The dosage of praziquantel for both acute and chronic patients was 60 mg/kg, 2 times/dx2 d. RESULTS: IgG antibody response was first detected at day 10 post infection by rSjLAP, rSjFBPA or the combined antigen assay. The mean absorbance (A450) on this day were 0.535 +/- 0.053, 0.595 +/- 0.033, 0.696 +/- 0.104 for group B; 0.548 +/- 0.060, 0.608 +/- 0.063, 0.621 +/- 0.090 for group C; and 0.415 +/- 0.038, 0.455 +/- 0.056, 0.498 +/- 0.077 for group A for rSjLAP, rSjFBPA and the combined assay respectively (P < 0.05). Early antibody level to both antigens was significantly higher in mice infected with 15 or 25 cercariae than those with 5 cercariae (P < 0.05). However, ELISA results in patients with confirmed schistosomiasis revealed positive rates of 97.4% (37/38) and 87.5% (84/96) for acute and chronic schistosomiasis with rSjLAP , 94.7% (36/38) and 88.5% (85/96) for acute and chronic schistosomiasis with rSjFBPA and 94.7% (36/38)and 85.4%(82/96) with both rSjLAP and rSjFBPA respectively. Statistical analysis showed no significant difference in the positive rate (P > 0.05). Also, rSjLAP and combined antigens showed a specificity of 96.7% (87/90) while that of rSjFBPA was 97.8% (88/90). There was a general decrease in the antibody titer of the patients after treatment. In 12 months after treatment it was 0.236 +/- 0.212 with rSjLAP, 0.287 +/- 0.191 with rSjFBPA, and 0.235 +/- 0.120 with both antigens respectively for acute cases; For chronic patients, it was 0.266 +/- 0.124, 0.261 +/- 0.143 and 0.265 +/- 0.140 in 12 months post-treatment, and 0.204 +/- 0.074, 0.176 +/- 0.074, and 0.176 +/- 0.073 in 2 years, respectively. For healthy control, it was 0.188 +/- 0.056, 0.173 +/- 0.45, and 0.184 +/- 0.051, respectively. No significant difference on antibody titer was found between treated patients and control (P > 0.05). The cross reaction with C. sinensis was 15.2% (5/33) for rSjLAP, 12.1% (4/33) for rSjFBPA and 9.2% (3/33) for combined antigens. With P. westermani, it was 15.0% (6/40), 12.5% (5/40) and 15.0% (6/40), respectively, and 8.1% (3/37) with hookworm infection. CONCLUSION: The study showed a satisfactory sensitivity and specificity of rSjLAP and rSjFBPA by ELISA which is promising for the immunological diagnosis of schistosomiasis.

Serological proteome-oriented screening and application of antigens for the diagnosis of Schistosomiasis japonica.

Schistosomiasis remains a major parasitic disease, with 200 million people infected and 779 million people at risk worldwide. The lack of reliable diagnostic techniques makes this disease difficult to control. In an attempt to discover useful candidates for the diagnosis of schistosomiasis, proteomics in combination with western blotting were employed in this study. This serological proteome assay yielded more than 30 immunodominant spots. Ten of these spots were precisely matched with a homologous two-dimensional electrophoresis (2-DE) gel and successfully identified by LC/MS-MS as corresponding to four different proteins. Of these proteins, SjLAP and SjFBPA were successfully expressed, and their recombinant protein products were further applied in the diagnosis of human Schistosomiasis japonica using ELISA. The ELISA results revealed sensitivities of 98.1% and 87.8% for acute and chronic schistosomiasis with rSjLAP and 100% and 84.7% with rSjFBPA, whereas the assays showed a specificity of 96.7% with both recombinant proteins. After treatment with praziquantel, the titres of the antibodies against both antigens declined significantly (P<0.001). Our data therefore suggest that these antibody-oriented recombinant proteins had a high efficacy for the diagnosis of S. japonica, and 2-DE based screening followed by LC/MS-MS has promising potential in the screening of candidate antigens for the diagnosis of schistosomiasis.

Application of signaling protein 14-3-3 and 26 kDa glutathione-S-transferase to serological diagnosis of Schistosomiasis japonica.

Schistosomiasis japonica is currently one of the most serious parasitic diseases and over 670000 people are infected in China by the end of 2006. In order to establish an effective diagnostic method, the gene coding for Sj14-3-3 and Sj26kDa GST were cloned and expressed separately in Escherichia coli as fusion protein with His-tag. The rSj14-3-3 and 26kDa rSjGST were combinedly used as antigens for enzyme-linked immunosorbent assays (ELISA) to diagnose acute and chronic S. japonica. Our results showed that the sensitivity in diagnoses of both acute and chronic schistosomiasis was 94.4% (67/71) and 80.7% (96/119), respectively. The specificity was 94.7% applying 132 sera from people living in S. japonicum-free areas. The data also showed that the recombinant proteins cross-react with Clonorchis sinensis and hookworms at a rate of 11.8% and 5.3% respectively. Parallel tests were conducted among ELISA, indirect hemagglutination assay (IHA) and circular ovum precipitin test (COPT) to determine anti-S. japonicum antibodies in sera of patients with schistosomiasis, healthy control, and those infected with other parasites and the results showed no significant difference in sensitivity for acute schistosomiasis between ELISA and IHA assays (chi(2)=1.33, P>0.05), but significant between ELISA and COPT assays (chi(2)=6.72, P<0.01). Our results also revealed significant difference in positive rate between ELISA and IHA (chi(2)=24.74, P<0.005), as well as between ELISA and COPT (chi(2)=58.14, P<0.005). These results suggest that the rSj14-3-3 and r26kDa SjGST would be effective diagnostic antigens for detection of antibodies to S. japonicum in human. Due to the easy production, high sensitivity and specificity, the recombinant proteins tested in this study can be considered as candidate reagent for immunological diagnosis of human schistosomiasis.