Untargeted serum metabolomics analysis of Trichinella spiralis-infected mouse

Abstract

Background Trichinellosis, caused by a parasitic nematode of the genus Trichinella, is a zoonosis that affects people worldwide. After ingesting raw meat containing Trichinella spp. larvae, patients show signs of myalgia, headaches, and facial and periorbital edema, and severe cases may die from myocarditis and heart failure. The molecular mechanisms of trichinellosis are unclear, and the sensitivity of the diagnostic methods used for this disease are unsatisfactory. Metabolomics is an excellent tool for studying disease progression and biomarkers; however, it has never been applied to trichinellosis. We aimed to elucidate the impacts of Trichinella infection on the host body and identify potential biomarkers using metabolomics. Methodology/Principal findings Mice were infected with T. spiralis larvae, and sera were collected before and 2, 4, and 8 weeks after infection. Metabolites in the sera were extracted and identified using untargeted mass spectrometry. Metabolomic data were annotated via the XCMS online platform and analyzed with Metaboanalyst version 5.0. A total of 10,221 metabolomic features were identified, and the levels of 566, 330, and 418 features were significantly changed at 2-, 4-, and 8-weeks post-infection, respectively. The altered metabolites were used for further pathway analysis and biomarker selection. A major pathway affected by Trichinella infection was glycerophospholipid metabolism, and glycerophospholipids comprised the main metabolite class identified. Receiver operating characteristic revealed 244 molecules with diagnostic power for trichinellosis, with phosphatidylserines (PS) being the primary lipid class. Some lipid molecules, e.g., PS (18:0/19:0)[U] and PA (O-16:0/21:0), were not present in metabolome databases of humans and mice, thus they may have been secreted by the parasites. Conclusions/Significance Our study highlighted glycerophospholipid metabolism as the major pathway affected by trichinellosis, hence glycerophospholipid species are potential markers of trichinellosis. The findings of this study represent the initial steps in biomarker discovery that may benefit future trichinellosis diagnosis. Author summary Trichinellosis is a zoonosis caused by consuming raw meat containing infective larvae of genus Trichinella nematodes. Trichinellosis patients can be found globally, and severe cases may die from myocarditis and heart failure. Currently, information on the molecular mechanisms of trichinellosis and precise biomarkers for the infection are scarce. To improve disease diagnosis and treatment, better understanding in these areas is required. Therefore, this study aimed to elucidate impacts of Trichinella infection on the host body and identify potential biomarkers with metabolomics, a holistic approach to studying global compound changes in organisms. Our study used a mouse model of trichinellosis, and sera were collected before and three timepoints after infection and explored for metabolomic data. Trichinella infection affected the glycerophospholipid metabolism pathway within the host body, and glycerophospholipid species were highlighted as potential biomarkers of the disease. Lipid molecules have never been proposed as markers of trichinellosis before; hence, the development of biomarkers based on findings of our study could be a novel approach to improve disease diagnosis in the future.