Recombinant Schistosoma japonicum egg ribonuclease SjCP1412 inhibits the activation of LX-2 hepatic stellate cells in vitro / 中国血吸虫病防治杂志

Objective To investigate the effect of recombinant Schistosoma japonicum egg ribonuclease SjCP1412 (rSjCP1412) on proliferation, cell cycle, apoptosis and activation of human hepatic stellate cells LX-2 in vitro, and explore the underlying mechanisms. Methods The rSjCP1412 protein was expressed in Escherichia coli BL21 by prokaryotic expression, and the highly purified soluble rSjCP1412 protein was prepared by Ni NTA affinity chromatography and urea gradient refolding dialysis. Yeast RNA was digested using 12.5, 25.0, 50.0 µg rSjCP1412 proteins at 37 °C for 2, 3, 4 h, and the enzymatic products were electrophoresed on 1.5% agarose gel to observe the RNAase activity of rSjCP1412 protein. The proliferation of LX-2 cells stimulated by different doses of rSjCP1412 protein for 48 hours was measured using CCK-8 assay, and the apoptosis of LX-2 cells stimulated by different doses of rSjCP1412 protein for 48 hours was detected using the Annexin V-FITC/PI double staining, while the percentage of LX-2 cells at G0/G1, S and G2/M phases of cell cycle following stimulation with different doses of rSjCP1412 protein for 48 h was detected by DAPI staining. The type I collagen, type III collagen and α-smooth muscle actin (α-SMA) mRNA expression was quantified using quantitative florescent real-time PCR (qPCR) assay and Western blotting at transcriptional and translational levels in LX-2 cells following stimulation with different doses of rSjCP1412 protein for 48 h, while soluble egg antigen (SEA) served a positive control and PBS without rSjCP1412 protein as a normal control in the above experiments. The expression of collagen I, α-SMA and Smad4 protein was determined using Western blotting in LX-2 cells following stimulation with rSjCP1412 protein, transforming growth factor-β1 (TGF-β1) alone or in combination, to examine the signaling for the effect of rSjCP1412 protein on LX-2 cells. Results The rSjCP1412 protein was successfully expressed and the highly purified soluble rSjCP1412 protein was prepared, which had a RNase activity. Compared with the normal group, the survival rates of LX-2 cells significantly decreased post-treatment with 12.5, 25.0, 50.0 µg/mL rSjCP1412 protein and SEA for 48 h (F = 22.417 and 20.448, both P values < 0.05). The apoptotic rates of LX-2 cells significantly increased post-treatment with 12.5, 25.0, 50.0 µg/mL rSjCP1412 protein for 48 h (F = 11.350, P < 0.05), and treatment with 12.5, 25.0, 50.0 µg/mL rSjCP1412 protein for 48 h resulted in arrest of LX-2 cells in G0/G1 phase (F = 20.710, P < 0.05). Treatment with 12.5, 25.0, 50.0 µg/mL rSjCP1412 protein for 48 h caused a significant reduction in relative expression levels of collagen I (F = 11.340, P < 0.05), collagen III (F = 456.600, P < 0.05) and α-SMA mRNA (F = 23.100, P < 0.05) in LX-2 cells, and both rSjCP1412 protein and SEA treatment caused a significant reduction in collagen I (F = 1 302.000, P < 0.05), α-SMA (F = 49.750, P < 0.05) and Smad4 protein expression (F = 52.420, P < 0.05) in LX-2 cells. In addition, rSjCP1412 protein treatment inhibited collagen I (F = 66.290, P < 0.05), α-SMA (F = 31.300, P < 0.05) and Smad4 protein expression (F = 27.010, P < 0.05) in LX-2 cells activated by TGF-β1. Conclusion rSjCP1412 protein may induce apoptosis of LX-2 cells and inhibit proliferation, cell cycle and activation of LX-2 cells through down-regulating Smad4 signaling molecules.

[Preliminary research on prokaryotic expression and immune protection of triosephosphate isomerase of Toxoplasma gondii].

OBJECTIVE: To study the prokaryotic expression and immune protection of triosephosphate isomerase (TPI) of Toxoplasma gondii in mice. METHODS: Total RNA was extracted from toxoplasma tachyzoites, and TPI fragment was amplified by PCR and cloned into the prokaryotic expression vector pET-28a (+). The target protein was induced with IPTG and purified by Ni-NTA affinity chromatography. The mice were immunized 4 times by emulsified TPI with adjuvant, and the last time was the strengthen immunization. At the same time, an adjuvant group and a normal group were set as controls. The blood samples were got from the tail vein of the mice, and the serum antibody titres were detected. All the mice were challenged with 400 toxoplasma tachyzoites to observe the survival time. RESULTS: The TPI gene was amplified from T. gondii cDNA by PCR. The recombinant vector TPI/pET-28a (+) was usefully constructed, and the TPI protein was expressed and purified. The serum antibody titre could be more than 100 thousand. After infected with toxoplasma tachyzoites, the survival time of the mice in the experimental group was longer than that of the mice in the control groups. CONCLUSIONS: The TPI protein of T. gondii could trigger the immunoprotection against T. gondii challenge in the mice.

[Progress of researches on diagnostic methods of current Schistosoma infection].

Now schistosomiasis is still a serious zoonosis which affects human health and hinders the economy development in endemic areas. Accurate diagnosis of the infection of Schistosoma is very significant in reducing hazards to human health and controlling the epidemic of schistosomiasis. This review summarizes recent advances in the laboratory diagnostic methods for current schistosome infection (including pathogenic, immunologic and molecular biologic methods) so as to provide the reference for prevention and control of schistosomiasis in the field.