Albendazole reduces endoplasmic reticulum stress induced by Echinococcus multilocularis in mice

Background Echinococcus multilocularis causes alveolar echinococcosis (AE), a rising zoonotic disease in the northern hemisphere. Treatment of this fatal disease is limited to chemotherapy using benzimidazoles and surgical intervention, with relatively frequent disease recurrence in cases without radical surgery. Elucidating the molecular mechanisms underlying E. multilocularis infections and host-parasite interactions aids developing novel therapeutic options. This study explored an involvement of unfolded protein response (UPR) and endoplasmic reticulum-stress (ERS) during E. multilocularis infection in mice. Methods E. multilocularis- and mock-infected C57BL/6 mice were subdivided six weeks after infection into vehicle and albendazole (ABZ) treated groups. Eight weeks later, liver tissue was collected to examine mRNA, microRNA (miR) and protein expression of UPR- and ERS-related genes. Results E. multilocularis infection upregulated UPR- and ERS-related proteins, including ATF6, CHOP, GRP78, ERP72, H6PD and calreticulin, whilst PERK and its target eIF2α were not affected, and IRE1α and ATF4 were downregulated. ABZ treatment in E. multilocularis infected mice reversed the increased ATF6 and calreticulin protein expression, tended to reverse increased CHOP, GRP78, ERP72 and H6PD expression, and decreased ATF4 and IRE1α expression to levels seen in mock-infected mice. The expression of miR-146a-5p (downregulated by IRE1α) and miR-1839-5p (exhibiting a unique target site in the IRE1α 3’UTR) were significantly increased in E. multilocularis infected mice, an effect reversed by ABZ treatment. Other miRs analyzed were not altered in E. multilocularis infected mice. Conclusions and Significance AE causes UPR activation and ERS in mice. The E. multilocularis -induced ERS was ameliorated by ABZ treatment, indicating its effectiveness to inhibit parasite proliferation and downregulate its activity status. ABZ itself did not affect UPR in control mice. Identified miR-146a-5p and miR-1839-5p might represent biomarkers of E. multilocularis infection. Modulation of UPR and ERS, in addition to ABZ administration, could be exploited to treat E. multilocularis infection. Author summary Alveolar echinococcosis is a zoonotic disease caused by the fox tapeworm Echinococcus multilocularis . Treatment of this fatal disease is limited to surgical intervention, preferably radical curative surgery if possible, and the use of parasitostatic benzimidazoles. It is not yet fully understood how the parasite can remain in the host’s tissue for prolonged periods, complicating the development of therapeutic applications. This work investigated an involvement of the unfolded protein response (UPR) and endoplasmic reticulum-stress (ERS) during E. multilocularis infection and upon treatment with albendazole (ABZ) in mice. The results revealed increased expression levels of the ERS sensor ATF6 and of downstream target genes in liver tissue of E. multilocularis- compared to mock-infected mice. Additionally, H6PD, generating NADPH within the endoplasmic reticulum, and the lectin-chaperone calreticulin were increased in E. multilocularis infected liver tissue while the expression of the ERS associated genes ATF4 and IRE1α were decreased. The miR-1839-5p and miR-146-p, linked to IRE1α, were elevated upon E. multilocularis infection, offering potential as novel biomarkers of alveolar echinococcosis. The observed gene expression changes were at least partially reversed by ABZ treatment. Whether modulation of UPR and ERS targets can improve the therapy of alveolar echinococcosis remains to be investigated. * ABZ : albendazole AE : alveolar echinococcosis ATF4 : activating transcription factor 4 ATF6 : activating transcription factor 6 CHOP : CCAAT/enhancer-binding protein homologous protein CNX : calnexin CRT : calreticulin CTRL : control E. multilocularis : Echinococcus multilocularis GRP78 : glucose-binding protein 78 eIF2α : eukaryotic initiation factor 2α ER : endoplasmic reticulum ERAD : ER-associated degradation ERP72 : endoplasmic reticulum resident protein 72 ERS : endoplasmic reticulum stress H6PD : hexose-6-phosphate dehydrogenase HRP : horse-radish peroxidase IRE1α : inositol-requiring enzyme 1α microRNA(s) : miR(s) PERK : protein kinase R (PKR) like ER kinase PVDF : polyvinylidene difluoride RIPA : radioimmunoprecipitation assay RT-qPCR : real-time quantitative polymerase chain reaction UPR : unfolded protein response XBP1(-s) : X-box binding protein 1 (-spliced)