Tirapazamine combined with photodynamic therapy improves the efficacy of ABZSO nanoparticles on Echinococcosis granulosus via further enhancing "breaking-then-curing".

BACKGROUND: Photodynamic therapy (PDT) has a promising application prospect in Echinococcus granulosus (Egs), however, the hypoxic environment of Egs and the hypoxia associated with PDT will greatly limit its effects. As a hypoxic-activated pre-chemotherapeutic drug, tirapazamine (TPZ) can be only activated and produce cytotoxicity under hypoxia environment. Albendazole sulfoxide (ABZSO) is the first choice for the treatment of Egs. This study aimed to explore the effects of ABZSO nanoparticles (ABZSO NPs), TPZ combined with PDT on the activity of Egs in vitro and in vivo. METHODS: The Egs were divided into control, ABZSO NPs, ABZSO NPs + PDT, and ABZSO NPs + TPZ + PDT groups, and the viability of Egs was determined using methylene blue staining. Then, the ROS, LDH and ATP levels were measured using their corresponding assay kit, and H2AX and TopoI protein expression was detected by western blot. The morphology of Egs with different treatments was observed using hematoxylin eosin (HE) staining and scanning electron microscopy (SEM). After that, the in vivo efficacy of ABZSO NPs, TPZ and PDT on Egs was determined in a Egs infected mouse model. RESULTS: In vitro experiments showed that the combined treatment of TPZ, ABZSO NPs and PDT significantly inhibited Egs viability; and significantly increased ROS levels and LDH contents, while decreased ATP contents in Egs; as well as up-regulated H2AX and down-regulated TopoI protein expression. HE staining and SEM results showed that breaking-then-curing treatment seriously damaged the Egs wall. Additionally, in vivo experiments found that the combination of ABZSO NPs, PDT and TPZ had more serious calcification and damage of the wall structure of cysts. CONCLUSIONS: ABZSO NPs combined with TPZ and PDT has a better inhibitory effect on the growth of Egs in vitro and in vivo based on the strategy of "breaking-then-curing".

Effect of Harmine and Its Derivatives Against Echinococcus granulosus and Comparison of DNA Damage Targets.

Cystic echinococcosis (CE) is a worldwide zoonotic disease. At present, the treatment options of CE are limited. The main drugs used in clinical chemotherapy of echinococcosis are albendazole and mebendazole, but they mainly exert longterm antiparasitic effects based on high doses. Therefore, there is an urgent need for effective and safe anti-CE drugs. Previous studies have identified harmine (HM) as a new anti-CE drug. In this study, the efficacy of harmine derivatives was evaluated in vitro and in vivo. The harmine derivatives were tested against E. granulosus protoscoleces (PSC) in vitro. The effect of harmine derivatives was time and concentration dependent at different concentrations, and the anti-CE effect was better than that of harmine. The mortality rate of PSC reached 100% on the 5th day after exposure to harmine derivatives at a concentration of 100 µmol · L -1. Compared with the untreated model control mice, the weight of the cyst was significantly reduced in infected mice treated with harmine derivatives. The effect of harmine derivatives was better than that of harmine, and there was significant difference between harmine derivatives and albendazole (P <0.001). Histopathological examination of experimental mice organs (liver, spleen, lung, brain and small intestine) showed that there was no change in the tissues except for mild inflammation in the liver. The neurotoxicity test in Caenorhabditis elegans showed that the derivative inhibited the movement, feeding, perceptual behavior and acetylcholinesterase activity of C. elegans , and its effect was lower than that of harmine. In addition, intervention with HM derivatives was preliminarily proved to cause DNA damage. This study reveals the potential of HM derivatives as a new class of anti-CE agents and indicates that Topo2a may be a promising target for the development of anti-CE drugs.