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

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BACKGROUND: Schistosomiasis, one of the most prevalent neglected tropical diseases, is treated exclusively with praziquantel, which targets only adult worms. High reinfection rates and the potential emergence of drug resistance emphasize the need for a deeper understanding of host-parasite developmental biology for innovative therapeutic targets. Most studies have focused on parasite-derived immunomodulators and proteolytic enzymes essential for host invasion, while the contribution of host-derived factors to parasite development has remained largely unexplored. Here, we identify and functionally characterize a host phospholipase that modulates parasite diacylglycerophospholipid metabolism and development. METHODS: Large-scale proteomic screening identified host platelet-activating factor acetylhydrolase (PAFAH) as a candidate schistosomicidal factor. Using a mouse model of schistosomiasis, we produced recombinant mouse PAFAH (MsPAFAH) and performed ex vivo killing assays on juvenile stages and adult worms. Parasite morphology and reproductive organ integrity were assessed by confocal and scanning electron microscopy. Alterations in glycerophospholipid distribution were quantified by UPLC-MS/MS-based fatty acid profiling, followed by rescue experiments with free fatty acid supplementation. RESULTS: MsPAFAH was upregulated in schistosome-infected mice and exhibited potent schistosomicidal activity against all life stages in the host. 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. MsPAFAH specifically decreased the availability of phospholipid species containing namely eicosenoic (20:1) and docosatetraenoic acid (22:4), while increasing levels of respective hydrolysis (lyso) products 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. CONCLUSIONS: Our findings reveal a previously unrecognized host-derived regulator of schistosome development, highlighting phospholipid metabolism as a promising therapeutic axis for consideration in schistosomiasis interventions.

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