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BACKGROUND Schistosomiasis is a neglected tropical disease caused by trematodes of the genus Schistosoma, with a limited treatment, mainly based on the use of praziquantel (PZQ). Currently, several aspartic proteases genes have already been identified within the genome of Schistosoma species. At least one enzyme encoded from this gene family (SmAP), named SmCD1, has been validated for the development of schistosomicidal drugs, since it has a key role in haemoglobin digestion by worms. OBJECTIVE In this work, we integrated a structure-based virtual screening campaign, enzymatic assays and adult worms ex vivo experiments aiming to discover the first classes of SmCD1 inhibitors. METHODS Initially, the 3D-structures of SmCD1, SmCD2 and SmCD3 were generated using homology modelling approach. Using these models, we prioritised 50 compounds from 20,000 compounds from ChemBridge database for further testing in adult worm aqueous extract (AWAE) and recombinant SmCD1 using enzymatic assays. FINDINGS Seven compounds were confirmed as hits and among them, two compounds representing new chemical scaffolds, named 5 and 19, had IC50 values against SmCD1 close to 100 μM while presenting binding efficiency indexes comparable to or even higher than pepstatin, a classical tight-binding peptide inhibitor of aspartyl proteases. Upon activity comparison against mammalian enzymes, compound 50 was selective and the most potent against the AWAE aspartic protease activity (IC50 = 77.7 μM). Combination of computational and experimental results indicate that compound 50 is a selective inhibitor of SmCD2. Compounds 5, 19 and 50 tested at low concentrations (10 uM) were neither cytotoxic against WSS-1 cells (48 h) nor could kill adult worms ex-vivo, although compounds 5 and 50 presented a slight decrease on female worms motility on late incubations times (48 or 72 h). MAIN CONCLUSION Overall, the inhibitors identified in this work represent promising hits for further hit-to-lead optimisation.
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Objective @#To investigate the role and mechanism of bone formation caused by the ratio of advanced platelet-rich fibrin (A-PRF) and β-tricalcium phosphate (β-TCP) in rabbit femur defect model, which provides a new idea for clinical treatment of bone defect.@*Methods @#Twenty-four New Zealand white rabbits were divided into model group, 1∶1 complex group (A-PRF∶β-TCP=1∶1), 2∶1 complex group (A-PRF∶β- TCP=2∶1) and 4∶1 complex group (A-PRF∶β- TCP=4∶1）, with 6 rabbits in each group. Femoral defect models were constructed in each group. In the composite group, the bone defect was filled with composite material, while in the model group, no material was filled. After 8 weeks, the animals were euthanized and specimens were collected. Bone mineral density (BMD), bone volume fraction (BV/TV), trabecular thickness (Tb.Th), trabecular separation (Tb.SP) and trabecular number (Tb.N) in femoral defect tissue were measured by micro-CT and photographed. Hematoxylin - eosin staining was used to detect the pathological changes of new bone tissue. The morphological changes of the new bone tissue were observed by scanning electron microscopy. Determination of phospho-mitogen activated protein kinase p38 (p-p38MAPK), CCAAT/enhancer binding protein homologous protein (CHOP) and phospho-cysteine aspartic protease-3 (p-Caspase3) in newborn femur by ELISA. The mRNA expressions of osteoprotegerin (OPG), bone morphogenetic protein-2 (BMP-2), receptor activator of nuclear factor kappa-B ligand (RANKL) and p38MAPK were detected by real-time quantitative PCR. The expression of OPG, BMP-2, RANKL, p-p38MAPK and p-Caspase3 protein in the new bone tissue was observed by immunohistochemistry. @*Results @#In the model group, bone formation in the femoral defect area was slow and osteogenic quality was poor. Compared with the model group, the bone formation and neocapillaries of femoral defect area in the complex group was good, BMD, BV.TV, Tb.Th, Tb.N were increased, and Tb.Sp were decreased, the expressions of p-p38MAPK, CHOP and p-Caspase3 were decreased, and the mRNA and protein expressions of OPG and BMP-2 were increased. The mRNA expression of RANKL and p38MAPK was decreased. Apoptosis in new bone tissue of each group showed the lowest apoptosis rate in samples of the 2∶1 complex group (P<0.05); A-PRF: β-TCP=2∶1 ratio has the best osteogenic effect. @*Conclusion@#The complex composed of A-PRF and β-TCP can promote the expression of OPG, inhibit the expression of RANKL and phosphorylation of p38MAPK, reduce the apoptosis of new bone tissue cells, and promote osteogenic differentiation.
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Objective: To investigate the morphological structure of ovarian follicular cells and biochemical parameters of both ovaries and fat bodies (sites of vitellogenesis) from Rhodnius (R.) prolixus infected with Trypanosoma (T.) rangeli. Methods: Adult virgin females of R. prolixus were fed upon a membrane apparatus containing heat-inactivated citrated rabbit blood and a suspension of T. rangeli epimastigotes (Macias strain). Females from the control group and all the males received parasitefree blood. Transmission electron microscopy was used to reveal the morphological aspects of ovarian follicle cells in both control and parasite-infected groups. Protein profile, proteolytic activities and Western blotting analyses were performed in either ovary or fat body samples of control and parasite-infected groups. Results: According to the ultrastructural data, T. rangeli infection elicited a degeneration process in the ovarian follicular cells of R. prolixus. Proteolytic assays indicated a reduction in the activity of aspartic peptidases in the ovary and fat body from parasite-infected group, while a significant increase in the cysteine peptidase activity was measured in both insect organs. Additionally, immunoblotting revealed that vitellogenin was overexpressed in the ovary of parasite-infected insects. Conclusions: T. rangeli infection seems to elicit an early programmed cell death in the ovarian follicle cells as well as induces the modulation on the activities of different peptidase classes in either ovaries or fat bodies and the overexpression of the vitellogenin in the ovary of R. prolixus.
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@#Trichinella spiralis is an important foodborne zoonotic parasite and it is necessary to develop vaccine to prevent T. spiralis infection in food animals. T. spiralis aspartic protease-2 (TsASP2) has been demonstrated to play a crucial role in larval invasion of intestinal epithelium cells (IECs). The purpose of this study was to assess the interaction between TsASP2 and IECs and to investigate the immune protection elicited by vaccination with rTsASP2. The results showed that the enzymatic activity of native aspartic protease was detected in crude proteins of all T. spiralis development stages other than NBL stage, the highest activity was observed in the IIL stage. The results of Western blot showed that TsASP2 protein was expressed at ML, IIL and AW but not NBL, and the TsASP2 expression level at IIL stage was significantly higher than those of other three worm stages (P < 0.05). The specific binding between rTsASP2 and IECs was observed by immunofluorescence test (IFT) and confocal microscopy, and the binding site was localized at the IEC membrane and this binding ability was inhibited by aspartic protease specific inhibitor pepstain A. The results of ELISA showed that the binding ability was protein dose-dependent. Vaccination with rTsASP2 triggered a mixed Th1/Th2 humoral and mucosal immune responses, as demonstrated by the elevation levels of Th1/Th2 cytokines (IFN-γ and IL-4) secreted by the spleen and mesenteric lymph nodes (MLNs) of immunized mice. The mice vaccinated with rTsASP2 exhibited a 54.17% reduction in enteral adult worms and a 54.58% reduction in muscle larvae after T. spiralis challenge. The results demonstrated that TsASP2 might be a potential molecular target for anti-Trichinella vaccines.
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AIM: To explore the effect of inhibiting proliferation and inducing apoptosis in human primary gastric tumor by the Agkis-trodon halys venom anti-tumor component (AHVAC-). METHODS: Human primary gastric cancer cells were isolated by trypsin digestion, serum-free culture, and purified by differential adherence method, and cells were identified by immunohistochemistry. Cell proliferation and toxicity assay (CCK-8) was used to detect the inhibition rate of AHVAC- in different concentrations of primary gastric cancer cells. Immunohistochemistry was used to verify the apoptosis of human primary gastric cancer cells induced by AHVAC- and the morphological changes were observed by Hematoxylin-Eosin staining (HE staining). AHVAC--induced primary gastric cancer cell transformation rate was detected by flow cytometry Annexin V/PI double staining.RESULTS: Seven human primary gastric cancer cells were successfully isolated and purified, and 11 cases failed. Immunohistochemical identifications of carcinoembryonic antigen (CEA) and broad-spectrum keratin protein (AE1/AE3) were positive for both antibodies. AHVAC- inhibited the proliferation of human primary gastric cancer cells and showed a dose-dependent effect (P<0.01). Immunohistochemistry showed that the expression level of cysteine aspartic protease-3 (Caspase-3) up-regulated with the increase of AHVAC- concentration. HE staining showed that with the increase of AHVAC- concentration, the cell gap increased, nuclear pyknosis, and apoptosis cells increased. Flow cytometry showed that the apoptosis rate of human primary gastric cancer cells up-regulated with the increase of AHVAC- concentration (P<0.05). CONCLUSION: AHVAC- can inhibit the proliferation and induce apoptosis in human primary gastric cancer cells in a dose-dependent manner.
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OBJECTIVE:To study the effect of grape seed procyanidins on protein expressions of cysteine aspartic protease 3 (Caspase-3), tumor necrosis factor-related receptors (TRAF6) in renal tissue of rats with renal ischemia-reperfusion injury (RIRI),and explore the protective mechanism of procyanidins on RIRI. METHODS:50 rats were randomly divided into sham op-eration group,model group,Shenfukang capsules group(positive control,600 mg/kg),procyanidins low-dose,high-dose groups (100,150 mg/kg),10 in each group. All rats were intragastrically administrated once a day,for 7 d. After administration,rats in other groups except for sham operation group were established the RIRI model.After the modeling successed of 24 h,levels of creati-nine(Cr),urea nitrogen(BUN)in serum,and protein expressions of Caspase-3,TRAF6 in renal tissue of rats in each group were detected,and apoptotic rate of renal tubular epithelial cells was determined. RESULTS:Compared with sham operation group,lev-els of Cr,BUN in serum in model group were significantly increased(P<0.05);protein expressions of Caspase-3,TRAF6 in re-nal tissue were obviously enhanced (P<0.05);apoptotic rate of renal tubular epithelial cells was obviously increased (P<0.05). Compared with model group,levels of Cr,BUN in serum in each administration group were obviously decreased(P<0.05);pro-tein expressions of Caspase-3,TRAF6 in renal tissue were obviously weakened(P<0.05);apoptotic rate of renal tubular epithelial cells was obviously decreased(P<0.05);and procyanidins high-dose group showed superior effect to low-dose group and Shenfu-kang granules group (P<0.05). CONCLUSIONS:Grape seed procyanidins can relieve the RIRI of rats,which may be achieved by reducing protein expressions of Caspase-3 and TRAF6 to inhibit the apoptotic rate of renal tubular epithelial cells.
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The objective of this study was to develop and validate of Structure-Based Virtual Screening (SBVS) protocol which was used to select the best pose of inhibitor-aspartic protease complex interaction in the active sites of HIV-1 protease, plasmepsin I, II, and IV. Retrospective validation was performed on enhanced dataset of ligands and decoys (DUD-E) for HIV-1 protease. The crystal structures 1XL2, 3QS1, 1SME, and 1LS5 were obtained from Protein Data Bank. The protocol was then challenged to re-dock the ligands to its origin places in the active sites by correlating Tanimoto coefficient (Tc) and binding affinity (Ei) with Root Mean Square Deviation (RMSD). Enrichment factor at 1% false positives (EF1%) values for Tc and Ei were 18.26 and 9.03, respectively, while the Area Under Curve (AUC) values for Tc and Ei were 76.84 and 60.95. The SBVS protocol was valid and showed better virtual screening qualities in ligand identification for HIV-1 protease compared to the original protocol accompanying the release of DUD-E and showed its ability to reproduce the co-crystal pose in the HIV-1 protease, plasmepsin I, II, and IV to its origin places in the active sites.
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Objective: To observe the effects of ethyl acetate extract from Huanglian Jiedu Decoction (EAHJD) on the virulence factors of Candida albicans. Methods: Egg-yolk medium, milk-plate medium, and olive oil emulsification were used respectively to test the activities of phospholipase (PL), aspartic protease (Sap), and lipase (Lip) of C. albicans. The water-hydrocarbon two-phase assay was applied to measure the cell surface hydrophobicity (CSH) of C. albicans. qRT-PCR was adopted to observe the expression of virulence factors related genes. Results: EAHJD had no effect on the activity of PL. EAHJD (1 250 μg/mL) could significantly inhibit the activity of PL and Lip better than that by 312 μg/mL EAHJD. EAHJD could reduce CSH of C. albicans in a dose-independent manner and CSH1 was down-regulated by 7.69, 3.57, and 2.95 folds by 1 250, 312, and 78 μg/mL EAHJD, respectively. The expression of secretory enzyme related genes displayed different changing folds: PLC1, Sap2, Sap3, Sap9, Lip3, Lip4, and Lip6 were down-regulated; PLB1, PLC2, Sap1, Sap10, and Lip5 had no distinct change treated by EAHJD. Conclusion: EAHJD could inhibit the activities of virulence factors of C. albicans.
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We assessed fluconazole susceptibility in 52 Candida tropicalis clinical strains using seven antifungal susceptibility methods, including broth microdilution (BMD) [standard M27 A3 (with neutral and acid pH), ATB Fungus 3, Vitek 2 system and flow cytometric analysis] and agar-based methods (disk diffusion and E-test). Trailing growth, detection of cell-associated secreted aspartic proteases (Saps) and morphological and ultrastructural traits of these clinical strains were also examined. The ranges of fluconazole 24 h-minimum inhibitory concentration (MIC) values were similar among all methods. The essential agreement among the methods used for MIC determinations was excellent and all methods categorised all strains as susceptible, except for one strain that showed a minor error. The presence of the trailing effect was assessed by six methods. Trailing positivity was observed for 86.5-100 percent of the strains. The exception was the BMD-Ac method where trailing growth was not observed. Morphological and ultrastructural alterations were detected in C. tropicalis trailing cells, including mitochondrial swelling and cell walls with irregular shapes. We tested the production of Saps in 13 C. tropicalis strains expressing trailing growth through flow cytometry. Our results showed that all of the C. tropicalis strains up-regulated surface Sap expression after 24 h or 48 h of exposure to fluconazole, which was not observed in untreated yeast strains. We concluded that C. tropicalis strains expressing trailing growth presented some particular features on both biological and ultrastructural levels.