An improved medium for in vitro studies of female reproduction and oviposition in Schistosoma japonicum.

BACKGROUND: Schistosomiasis is a disease primarily caused by eggs laid by pathogens called schistosomes. Among the schistosome species infecting humans, Schistosoma japonicum possesses the largest fecundity; each adult female produces an average of 3500 eggs per day. The lack of proper culture conditions supporting continuous oviposition in vitro has precluded detailed investigation of mechanisms regulating sexual maturation and egg production in Schistosoma japonicum. METHODS: We optimized in vitro culture conditions by replacing reagents that are part of the classical ABC169 medium. Fast Blue BB staining and 4',6-diamidino-2-phenylindole (DAPI) labeling were applied to observe the sexual development status of the females. In vitro RNA interference (RNAi) technology was used to validate the capability of the modified medium. The detection of male ß-alanyl-tryptamine (BATT) was conducted using liquid chromatography-mass spectrometry (LC-MS). RESULTS: Both m-AB169 (1640) and AB169 (1640) media are capable of facilitating the sexual development of paired virgin female S. japonicum, as well as sustaining the mature reproductive organs and egg production of adult S. japonicum for at least 22 days in vitro. M-AB169 (1640) provided a more stable condition for supporting the sexual maturity of female S. japonicum, as evidenced by the consistent initiation of egg production compared with AB169 (1640). Through a comparative analysis of S. japonicum and S. mansoni in diverse media, we demonstrated that these closely related species display distinct demands for their sexual development and egg production, suggesting a potential influence of nutritional factors on the observed variations in host ranges among different schistosome species. Importantly, we successfully identified the presence of the pheromone ß-alanyl-tryptamine (BATT) in S. japonicum, previously identified in S. mansoni, highlighting its conserved role in schistosome reproductive development. Through the employment of double-stranded RNA (dsRNA) treatment to silence two genes that are involved in either the male (gli1, glioma-associated oncogene homolog 1) or female (vf1, vitellogenic factor 1) side in male-induced female reproductive development of S. mansoni, we confirmed that the combination of m-AB169 (1640) and RNAi technology has the capacity to facilitate in vitro studies of S. japonicum's reproductive and oviposition processes. CONCLUSIONS: We developed a novel medium, m-AB169 (1640), that not only maintains the mature reproductive organs and continuous oviposition of adult female Schistosoma japonicum for up to 22 days but also supports the reproductive development and subsequent egg-laying of virgin females after pairing with male worms. This study provides a valuable in vitro platform for functional studies of the mechanisms underlying the fascinating biology of the female sexual development and egg production of S. japonicum, which may accelerate the development of new strategies targeting schistosome egg production.

Suppressive effect of pseudolaric acid B on Echinococcus multilocularis involving regulation of TGF-ß1 signaling in vitro and in vivo.

Echinococcus multilocularis, the causative agent of alveolar echinococcosis (AE), severely threats human health and livestock farming. The first line of chemotherapeutic drug for AE is albendazole, which limits rapid extension of E. multilocularis metacestodes, but is rarely curative for AE, with severe side effects in long-term use, thus development of new anti-echinococcal drugs is mandated. Pseudolaric acid B (PAB) has long been used to treat fungal-infected dermatosis, and exerted anti-tumor, -fertility, -angiogenesis, -tubulin and antiparasitic activity. However, the effect of PAB against Echinococcus spp. remains unclear. The present study is to understand the effect of PAB against E. multilocularis in vitro and in vivo, and identify potential anti-echinococcal mechanism, as well as its toxicity. After exposure to PAB at 20 µg/ml, significant reduction of the survival rate and substantial ultrastructural destructions in E. multilocularis protoscoleces were observed in vitro. Furthermore, the wet weight of E. multilocularis cysts in the infected mice was significantly decreased after treatment with PAB (40, 20 or 10 mg/kg) for 12 weeks. Meanwhile, significant increase of both protein and mRNA expression of transforming growth factor beta 1 (TGF-ß1) was detected in the serum and liver of the infected mice, whereas PAB administration lowered its expression significantly. The toxicity tests demonstrated that PAB displayed lower cytotoxicity to human liver and kidney cells (HL-7702 and HK-2 cell) with IC50 = 25.29 and 42.94 µg/ml than albendazole with IC50 = 3.71 and 21.22 µg/ml in vitro, and caused lower hepatoxicity and nephrotoxicity in mice than ABZ. Our findings indicated that PAB possesses potent anti-echinococcal effect, with lower toxicity than albendazole, implying a potential chemotherapeutic agent for AE. Additionally, the present study demonstrated that the suppressive effect of PAB on the parasite may involve down-regulation of TGF-ß1 signaling.

Silencing TUBB3 Expression Destroys the Tegument and Flame Cells of Echinococcus multilocularis Protoscoleces.

Alveolar echinococcosis (AE), caused by infection with the larvae of Echinococcus multilocularis, is a neglected tropical disease and zoonosis that causes remarkable morbidity in humans and has economic importance in the livestock industry worldwide. The growth of this parasite resembles the invasion and proliferation of malignant tumours. Microtubules, especially the ß-tubulin subunit in the exposed end, are the targets of many antitumour drugs. However, the role of TUBB3, which is the most studied isotype in solid tumours and is also a marker of biological aggressiveness associated with the modulation of tumour metastatic abilities in the growth and development of platyhelminths, is unknown. In this study, protoscoleces (PSCs) are cultivated in monophasic medium in vitro. Using electroporated short interfering RNA (siRNA), EmTUBB3 knockdown was performed with two EmTUBB3-specific siRNAs (siRNA-1 and siRNA-2). qRT-PCR was performed to detect the expression of TUBB3. PSCs viability and the evagination rate and number of body contractions were quantified under a light microscope. Scanning electron microscopy (SEM) and transmission electron microscopy (TEM) were used to observe the ultra-morphological changes of the parasites. After siRNA interference, the EmTUBB3 expression in E. multilocularis PSCs was significantly reduced. Reduced viability, a decreased evagination rate and a decreased number of body contractions were also documented. In particular, shrinkage and roughness of the tegument were observed. Ultrastructural changes included marked damage to flame cells, cracked cilia structures enclosed in the cell body and ruptured microtubule structures. EmTUBB3 possibly plays a crucial role in tegument and flame cell integrity in E. multilocularis PSCs. Novel drugs targeting this specific beta-tubulin isotype in E. multilocularis are potential methods for disease control and deserve further attention.

Antitumor Effect of Pseudolaric Acid B Involving Regulation of Notch1/Akt Signaling Response in Human Hepatoma Cell In Vitro.

Background: Liver cancer, particularly hepatocellular carcinoma (HCC), is the fourth leading cause of cancer-related death worldwide. Sorafenib is a crucial drug for the treatment of advanced HCC, but it is difficult to meet the challenge of increasing clinical demands due to its severe side effects and drug resistance. Hence, development of novel antitumor drugs is urged. Previous studies showed that pseudolaric acid B (PAB) could reduce the expression of protein kinase B (PKB/Akt), a downstream effector of Notch signaling, facilitating cell apoptosis in HCC. The disruption of Notch signaling was verified to exacerbate malignant progression and drug resistance, however, the antitumor effect of PAB on Notch signaling in HCC remains unclear. Thus, this study aims to investigate the anti-HCC effect of PAB in association with the regulation of Notch1/Akt signaling. Methods: CCK-8 assay and transwell assay were used to examine the cell proliferation and invasion in Huh7 cells after treatment with PAB and a Notch inhibitor DAPT. Moreover, the cell cycle of Huh7 cells after treatment with PAB was analyzed using flow cytometry. Finally, the changes of Notch1, Jagged1, Hes1, and Akt expression at the protein and mRNA level in Notch1/Akt signaling in Huh7 cells after treatment with PAB and DAPT were analyzed using immunofluorescence assay and real-time qPCR. Results: The proliferation rate of Huh7 cells exposed to PAB of 0.5, 1, 2, 4, 8, 10, 20, 40, 80, 100, and 200 µmol/L revealed a time-and dose-dependent decrease in vitro, showing cell cycle arrest at G2/M phase (P < 0.05). Furthermore, compared with the untreated group, at the concentration of 40 µmol/L, the proliferation rate and invasion rate of Huh7 cells in PAB, DAPT, and PAB-DAPT combination (PAB + DAPT) group were significantly decreased (P < 0.05), but the PAB + DAPT showed no synergistic antiproliferation and anti-invasion effect in comparison with PAB treatment alone (P > 0.05). In addition, compared with the untreated group, PAB and DAPT alone significantly downregulated the expression of Notch1, Jagged1, Hes1, Akt mRNA, or/and protein in Huh7 cells (P < 0.05), but there was no significant difference in synergistic downregulated effect between the PAB + DAPT group and the PAB group (P > 0.05). Conclusion: PAB can suppress proliferation and invasion of HCC cells through downregulating the expression of Notch1/Akt signaling protein and mRNA, and may be a potential novel antitumor drug candidate for the clinical treatment of HCC in the future.

Slow-release praziquantel for dogs: presentation of a new formulation for echinococcosis control.

BACKGROUND: Echinococcosis is a serious, zoonotic, parasitic disease with worldwide distribution. According to a epidemiological survey in 2012 in China, there are 20,000 infected patients and more than 50 million people at the risk. As the dog is the main, definitive host, the Government of China encourages monthly praziquantel treatment of every dog. However, this is difficult to achieve in geographically challenging areas, such as the Tibetan plateau, where there are also many dogs without owners. To overcome these problems, we investigated the transmission blocking capacity of a slow-release formulation of praziquantel administered by subcutaneous injection. METHODS: The impact of a slow-release preparation of two pharmacokinetically stereoselective praziquantel enantiomers, i.e., R-(-)-praziquantel (R-PZQ) and S-(+)-praziquantel (S-PZQ) absorbed into a biodegradable polymer was studied in beagle dogs (N = 6). The preparation was given by subcutaneous injection using a single dose of 100 mg/kg. Chiral-selective, high-performance liquid chromatography (HPLC) and high-resolution mass spectrometry (HRMS) were applied to measure the praziquantel enantiomers in the plasma of the dogs. The lower limit for estimating plasma concentrations accurately for R-PZQ was 4 ng/ml and for S-PZQ 20 ng/ml. The pharmacokinetic parameters were calculated by a noncompartmental analysis model using Drug Analyze System (DAS) software 2.0. The SPSS 19.0 software was used for statistical analysis, and the statistical comparison between enantiomers was assessed using the two-tailed t-test. RESULTS: Two hours after administration, peak concentrations of R-PZQ and S-PZQ: 321 ± 26 and 719 ± 263 ng/ml, respectively, were achieved. After 180 days, the average plasma concentration of R-PZQ in the six dogs had decreased to 13 ng/ml. The average concentration value of S-PZQ was higher than that of R-PZQ in the first 90-day period but fell afterwards and could not be accurately estimated when dropping below 20 ng/ml (the lower methodological limit for this enantiomer). Taking all the dogs into account, the average maximum concentration (Cmax) of S-PZQ in plasma over the first 3 months was higher than that of R-PZQ by 114.0% (P < 0.05), while the average mean retention time (MRT) of R-PZQ in plasma was higher than that of S-PZQ by 96.3% (P < 0.05). CONCLUSIONS: Praziquantel given as an in situ slow-release formulation by subcutaneous injection resulted in concentrations of the active principle in beagle dogs, which should be capable of resisting new Echinococcus infections for at least 6 months. The new formulation of praziquantel represents a potential, alternative way of presenting medication against tapeworm infections in dogs.