Anisuzzaman, A. | bioRxiv Science

bioRxiv2025

Host-specific platelet-activating factor acetylhydrolase selectively remodels diacylglycerophospholipids to control schistosome development

BackgroundSchistosomiasis, a major neglected tropical disease, is currently treated with only one drug, praziquantel (PZQ), effective only against adult worms. However, high reinfection rates and potential development of drug resistance following widespread use of PZQ emphasize the need for a deeper molecular understanding of the host-parasite crosstalk as a basis for urgently needed novel drugs. Here, we identify and characterize a soluble host-derived schistosomicidal phospholipase that influences the diacylglycerophospholipid metabolism and, thereby, the survival and development of Schistosoma mansoni. MethodsLarge-scale proteomic screening identified host platelet-activating factor acetylhydrolase (PAFAH) as a potential schistosomicidal factor. Ultra-performance tandem mass spectrometry and electron microscopy imaging were employed to demonstrate the relevance and the lethal effects of recombinant expressed mouse PAFAH (MsPAFAH) on all juvenile stages and adult parasites from a mouse model of schistosomiasis. Quantitative lipidomic analysis revealed MsPAFAH-impaired glycerophospholipid distribution and metabolism and following free fatty acid supplementation. ResultsMsPAFAH was upregulated in schistosome-infected mice and exhibited potent schistosomicidal activity against all parasite life stages ex vivo. In contrast, human PAFAH had no effect on parasite viability. MsPAFAH treatment led to profound impairments in worm fecundity, pairing stability, reproductive organ integrity, and stem cell development. This activity was associated with substantial sex-dependent changes in ether-phospholipid composition and distribution within the schistosome tegument. MsPAFAH specifically decreased the availability of phospholipid species containing unsaturated fatty acids, namely eicosenoic (20:1) and docosatetraenoic acid (22:4), while increasing levels of respective hydrolysis (lyso) products of diacyl- and ether-phospholipids (carrying 20:1 or stearic acid (18:0)), predominantly in males. Supplementation of metabolized fatty acids C20:1/eicosenoic acid and 22:4/adrenic acid rescued the viability of female worms, confirming the essential role of the metabolism of these diacylglycerophospholipids in schistosome survival. ConclusionsThese findings unravel how a host phospholipase interferes with schistosome biology and development by regulating diacylglycerophospholipid availability and can thus open new avenues for schistosomiasis drug development and control.

systems biology↗

bioRxiv2018

A novel cell-free method to culture Schistosoma mansoni from cercariae to juvenile worm stages for in vitro drug testing

BackgroundThe arsenal in anthelminthic treatment against schistosomiasis is limited and relies almost exclusively on a single drug, praziquantel (PZQ). Thus, resistance to PZQ could constitute a major threat. Even though PZQ is potent in killing adult worms, it has been shown to be limited in its activity against earlier developmental stages. Current in vitro screening strategies for new drugs depend on newly transformed schistosomulae (NTS) for initial hit identification, thereby limiting sensitivity to new compounds predominantly active in later developmental stages. Therefore, the aim of this study was to establish a highly standardized, straightforward and reliable culture method to generate and maintain advanced larval stages in vitro. We present here how this method can be a valuable tool to test drug efficacy at each discrete intermediate larval stage, reducing the reliance on animal use (3Rs).\n\nMethodology/principal findingsCercariae were mechanically transformed into skin-stage (SkS) schistosomulae and successfully cultured under serum-free and cell-independent conditions for up to four weeks with no loss in viability. Under these conditions, larval development halted at the lung-stage (LuS). Addition of human serum (HSe) propelled further development into juvenile worms within eight weeks. Skin and lung stages, as well as juvenile worms, were submitted to 96-well format drug screening assays using known anti-schistosomal compounds such as PZQ, oxamniquine (OXM), mefloquine (MFQ) and artemether (ART). Our findings showed stage-dependent differences in larval susceptibility.\n\nConclusionWith this robust and highly standardized in vitro assay, important developmental stages of S. mansoni up to juvenile worms can be generated and maintained over prolonged periods of time. The phenotype of juvenile worms when exposed to reference drugs was comparable to previously published works for ex vivo harvested adult worms. Therefore, this in vitro assay can help reduce reliance on animal experiments in the search for new anti-schistosomal drugs.\n\nAuthor SummarySchistosomiasis remains a major health threat, predominantly in developing countries. Even though there has been some progress in search of new drugs, praziquantel remains the only available drug. Probably the most important advance in the search for new drugs was in vitro transformation of cercariae and their subsequent culture. However, hit identification in compound screenings is exclusively tested in skin stage parasites and is only confirmed for more mature worms in a subsequent step. This is in part due to the lack of an easy culture system for advanced-stage parasites. We present here a reliable and highly standardized way to generate juvenile worms in vitro in a cell-free culture system. The inclusion of in vitro drug tests on advanced-stage parasites in initial hit identification will help to identify compounds that might otherwise be overlooked. Furthermore, the ability to continuously observe the parasites development in vitro will provide an important platform for a better understanding of its maturation in the human host. Taken together, this opens up new avenues to investigate the influence of specific cell types or host proteins on the development of Schistosoma mansoni and provides an additional tool to reduce animal use in future drug discovery efforts (3Rs).

microbiology↗