Abstract text

Introduction

Schistosomiasis, caused among others by the parasitic trematode species Schistosoma mansoni, leads to chronic inflammation and finally to liver fibrosis. If untreated, the disease can cause life-threatening complications. The current treatment of schistosomiasis is mainly based on a single drug, Praziquantel (PZQ). Due to the frequent use of PZQ, there is upcoming fear of emerging resistance. Therefore, it is necessary to find alternative drugs. Screening of potential drugs is currently based on in vitro tests against different stages of the parasite. An attractive alternative is the establishment of enzyme assays with potential target proteins found in the parasite. With the use of such assays, large compound libraries can be tested in high‑throughput screenings (HTS) without the need for animal experiments and in a time- and cost-efficient manner.

Objectives

A potential target protein for such HTS, based on its role in detoxification processes in other organisms, is an aldose reductase (AR) orthologue in S. mansoni (Smp_053220, SmAR). This assumption is supported by the ubiquitous and sex-independent expression in S. mansoni [1, 2] and by a study in Schistosoma japonicum where treatment with a specific AR inhibitor showed a clear decrease in worm activity [3].

Materials & Methods

SmAR was recombinantly expressed in Escherichia coli strain BL21(DE3) and purified by immobilized metal ion affinity chromatography. The following buffer exchange was carried out performing size exclusion chromatography. Enzyme activity and IC50‑values for potential inhibitors were determined using the established enzyme assay.

Results

The enzyme was found to be active in vitro. A number of tested compounds, synthesized in the working group of Prof. Schlitzer (Philipps Universität Marburg), showed a clear inhibition of the enzyme and provide a solid basis for optimization and further development.

Conclusion

The successful purification of SmAR in sufficient amounts and the confirmed activity in the enzyme assay enabled first inhibitor screenings. Next steps will be further characterisation of the enzyme itself and possibly later on the performance of HTS.

Literature

[1] Wendt G, et al. Science. 2020;39(6511):1644-1649

[2] Lu Z, et al. Sci Data. 2017;4:170118

[3] Liu J, et al. Parasites & Vectors. 2013;6:162