Parasite-derived microRNAs in plasma as novel promising biomarkers for the early detection of hydatid cyst infection and post-surgery follow-up.

Currently, cystic echinococcosis (CE) follow-up is a serious concern among surgeons. MicroRNAs (miRNAs) are small, endogenous, non-coding RNAs which are present in human body fluids in a highly stable form. Recently, it is observed that Echinococcus granulosus expresses a large number of miRNAs in its developmental stages. The current study aimed at evaluating the capacity of parasitic miRNAs to serve as plasma biomarkers for hydatid cysts before and after CE surgery. Hydatidosis patients were identified using radiological and histopathological examinations. Following RNA extraction and cDNA synthesis, the expression levels of parasite-derived miRNAs including egr-miR-71 and egr-let-7 were quantitatively evaluated using real-time polymerase chain reaction (RT-PCR) in 30 hydatid cyst-infected individuals before surgery and an equal number of healthy controls. Then, three- and six-month follow-ups were performed after cystectomy. To analyze parasite-derived miRNAs, the relative fold change between uninfected and infected samples was determined and normalized to hsa-miR-16-5p as the housekeeping internal control. RT-PCR demonstrated that egr-miR-71 and egr-let-7 were specifically amplified in all the plasma samples from the infected individuals with hydatid cyst; yet they were significantly down-regulated at three and six months' post-surgery (P < 0.05). The egr-miR-71 had a higher level of expression in larval stage compared with egr-let-7. The results of the current study indicated that hydatid cyst-derived miRNAs including egr-miR-71 and egr-let-7 can be detected in human plasma. Considering the changes in the expression levels of these miRNAs after three and six months, it seems that these miRNAs, especially egr-miR-71, could serve as novel promising biomarkers for the early diagnosis and monitoring of hydatidosis.