Treatment of Schistosoma mansoni with miltefosine in vitro enhances serological recognition of defined worm surface antigens

Abstract

BackgroundMiltefosine, an anti-cancer drug that has been successfully repositioned for treatment of Leishmania infections, has recently also shown promising effects against Schistosoma spp targeting all life cycle stages of the parasite. The current study examined the effect of treating Schistosoma mansoni adult worms with miltefosine on exposure of worm surface antigens in vitro.Methodology/Principal findingsIn an indirect immunofluorescence assay, rabbit anti-S.mansoni adult worm homogenate and anti-S. mansoni infection antisera gave strong immunofluorescence of the S. mansoni adult worm surface after treatment with miltefosine, the latter antiserum having previously been shown to synergistically enhance the schistosomicidal activity of praziquantel. Rabbit antibodies that recognised surface antigens exposed on miltefosine-treated worms were recovered by elution off the worm surface in low pH buffer and were used in a western immunoblotting assay to identify antigenic targets in a homogenate extract of adult worms (SmWH). Four proteins reacting with the antibodies in immunoblots were purified and proteomic analysis (MS/MS) combined with specific immunoblotting indicated they were the S. mansoni proteins: fructose-1,6 bisphosphate aldolase (SmFBPA), Sm22.6, alkaline phosphatase and malate dehydrogenase. These antibodies were also found to bind to the surface of 3-hour schistosomula and induce immune agglutination of the parasites, suggesting they may have a role in immune protection.Conclusion/SignificanceThis study reveals a novel mode of action of miltefosine as an anti-schistosome agent. The immune-dependent hypothesis we investigated has previously been lent credence with praziquantel (PZQ), whereby treatment unmasks parasite surface antigens not normally exposed to the host during infection. Antigens involved in this molecular mechanism could have potential as intervention targets and antibodies against these antigens may act to increase the drug’s anti-parasite efficacy and be involved in the development of resistance to re-infection.

Praziquantel&ndash;lipid nanocapsules: an oral nanotherapeutic with potential <em>Schistosoma mansoni</em> tegumental targeting

“…43 More recently, MFS was shown to unmask parasite surface antigens not normally exposed to the host during infection, enhancing their serological recognition. 53 In the present study, inclusion of MFS and OA in PZQ-OA-MFS-LNCs did not significantly enhance antischistosomal activity (Tables 2 and 3), probably because of the lower MFS dose used (10 mg/kg) and masking of OA effects by Span 80 (sorbitan monoleate), reported to exert a fusogenic effect on phospholipid vesicles. 54 PK data indicated an increased PZQ bioavailability (Table 4), contributing to an enhanced PD activity by LNCs.…”

Multi-center screening of the Pathogen Box collection for schistosomiasis drug discovery

“…The mechanism of action of miltefosine may depend on the interplay between parasite and host. Thus, El-Faham and colleagues [45] demonstrated that treating parasites with miltefosine enhances serological recognition of defined adult worm surface antigens. The absence of activity here may suggest a stage-specific mode of action, i.e.…”

Arachidonic acid: Physiological roles and potential health benefits – A review

“…The schistosomicidal action of ARA is based on excessive hydrolysis of parasite surface membrane SM. Interestingly, Miltefosine, a hexa -decyl-phosphocholine, which interferes with proper biosynthesis of SM, was recently documented as a potent schistosomicide in vitro and in vi vo [106] .…”

“…Disruption of the tight SM-based hydrogen bond network around cancer cells may allow contact inhibition processes to proceed and cell proliferation to stop [77] , whereby the primary SM catabolite, ceramide released following SM hydrolysis is a renowned secondary messenger involved in programmed cell death [117] . It is of importance to recall that Miltefosine, which has been approved for the treatment of breast cancer metastasis, and is currently used for the treatment of cutaneous metastases of mammary carcinoma significantly inhibits SM biosynthesis in human hepatoma and other tumor cells [106] , [118] , [119] , [120] , [121] . The likely mechanism of action of this phospholipid analogue is inhibition of phosphatidylcholine biosynthesis, thus hindering SM metabolism, and substantially increasing the levels of ceramide [120] , [121] .…”