Metabolomic profiling of active and inactive liver cystic echinococcosis

Cystic Echinococcosis (CE) is one of the life-threatening diseases worldwide. It is a parasitic zoonosis caused by tapeworms of the species Echinococcus granulosus sensu lato (s.l). The treatment options of CE vary from simple "watch and wait" approach to invasive treatment, based on the type and especially the nature of the cyst (active/inactive). Serological tests are inadequate to distinguish between active and inactive CE. A diagnostic reference that can determine whether the cyst is active or inactive can easily guide the treatment strategy. We aimed to test whether gas chromatography-mass spectrometry (GC-MS) and liquid chromatography-quadropole time of flight mass spectrometry (LC-qTOF-MS) based metabolomics can establish a plasma metabolic fingerprint of CE patients and identify a diagnostic reference to discriminate active and inactive CE cysts. Metabolite concentrations were measured in plasma samples of 36 active CE patients, 17 inactive CE patients and 31 healthy controls. Multivariate statistical analysis on 232 identified metabolites obtained from two analytical platforms was performed by using principle component analysis (PCA) and partial least square-discriminant analysis (PLS-DA) methods. The PLS-DA scores plot of the combined data set demonstrated a good separation between the groups. Compared to the healthy control group, decreased levels of squalene and increased levels of glyceric acid, 3-phosphoglycerate, glutamic acid, palmitoleic acid and oleic acid were determined in the CE patients. However, decreased levels of 3-phosphoglycerate and increased levels of 4-hydroxyphenylacetylglutamine, docosahexanoic acid were determined in active CE patients compared to the inactive CE patients. Determination of differences in metabolites may provide detailed understandings of potential metabolic process associated with active and inactive CE patients, and altered specific metabolic changes may provide some clues to obtain diagnostic reference for CE. This study has certain limitations: a. various factors affecting results of metabolomic studies such as lifestyle and dietary habits of the patients could not be fully controlled b. other infectious or malignant diseases of the liver should also be included as a positive control to evaluate the specificity of the diagnostic references.