The Promise of Antimicrobial Peptides for Treatment of Human Schistosomiasis

Abstract

Schistosomiasis sometimes referred to as bilharzia ranks high among the common neglected human tropical diseases. Parasitic trematode flatworm belonging to the genus Schistosoma is responsible for this acute and chronic disease. Its prevalence is rapidly increasing in the tropical regions worldwide; however, its economic and global health impact is grossly underestimated. There are five recognized species of schistosome parasitizing humans but the common species causing the disease are S. haematobium, S. japonicum and S. mansoni. Over the years, praziquantel, due to its advantage over other drugs employed in the treatment of schistosomiasis especially because of its effectiveness against all schistosoma species has remained the drug of choice. Unfortunately, due to drug pressure, some reports of praziquantel resistance in the treatment of some strains of S. haematobium and S. mansoni have been documented in literature. This has necessitated the search for novel anti-schistosomal agents as alternatives to praziquantel treatment. Currently, antimicrobial peptides are gaining prominence as possible sources of novel drugs in the control and treatment of schistosomiasis. A major driving force for evaluating antimicrobial peptides is their general diverse therapeutic applications, basically due to their size and properties as well as their broad spectrum of activities. Therefore, antimicrobial peptides are attractive candidates with promising results that may overcome drug resistance problems in search for novel therapeutic agents for the control and treatment of schistosomiasis.

Natural Products with Antischistosomal Activity

“…Peptides Although antimicrobial peptides have recently gained prominence as possible sources of novel drugs in the control and treatment of schistosomiasis [107], only dermaseptin 01 has been described with antischistosomal activity to date [46,47].…”

Universal Stress Proteins as New Targets for Environmental and Therapeutic Interventions of Schistosomiasis

“…Presently, the likes of praziquantel, oxamniquine and artemisinin are considered as defence systems against the disease. However, oxamniquine does not treat all schistosome infections, its target is only limited to S. mansoni adult males, with less action against female and juvenile worms [23]. Use of the drug is mainly restricted to Brazil and South American countries but has been replaced by praziquantel as the principal drug and main line of treatment against schistosomiasis since the mid-2000s [24,25].…”

“…The drug seems stage-dependent, only effective on 1–2 weeks old larvae and 5 weeks and older adult worms [23]. Additionally, the mode of action still remains obscure despite decades of research [31].…”

“…Recently, antimicrobial peptides (AMPs) have come onto the scene as promising alternative anti-schistosomal tools due to their multifunctional properties. It has been suggested that AMPs may play a role against schistosomiasis by acting as immunostimulators, ROS scavengers or through elimination of schistosomulae by selective cytotoxicity [23]. …”

“…The worms are characterised by having a blind digestive tract, advanced neural, excretory and reproductive organs, two ending suckers and a greyish-white tegument that covers the 7–20 mm body of the worm [3,22]. Females reside in the gyneacophoric canal of the male and together form a nematode-like appearance [5,23]. …”