Inhibition of proteolysis by the hematophagous Eudiplozoon nipponicum
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| Year of publication | 2017 |
| Type | Conference abstract |
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| Description | Eudiplozoon nipponicum (Monogenea: Diplozoidae) is an obligatory hematophagous parasite of the common carp (Cyprinus carpio). The blood degradation by this species involves a cascade of cysteine and aspartic proteases hypothetically regulated by protease inhibitors (e.g. cystatins and stefins). These inhibitory molecules are also known to have impact on immunomodulation of the host and the repair of its tissue damaged by the parasite. Our study aims to reveal the biological function of the stefin of E. nipponicum which was detected in the transcriptome and excretory-secretory products of adult individuals. We prepared recombinant form of E. nipponicum stefin (rEnStef) in E. coli BL21 bacterial strain using pET19b expression plasmid vector. By adoption of fluorometric assay we observed efficient inhibition of cysteine peptidases (cathepsins L and B from E. nipponicum and mouse cathepsin L) via its conserved papain-binding domain. Surprisingly legumain (asparaginyl endopeptidase) inhibition was detected probably due to legumain-binding domain, untypical for stefins. rEnStef blocked proteolytic degradation of hemoglobin mediated by cysteine peptidases in the excretory-secretory products, soluble protein extracts from E. nipponicum and by recombinant cathepsins L3 and B of E. nipponicum, which manifests its role in blood digestion. rEnStef any effect on the activation of complement in carp’s plasma or oxidative burst in full blood studied using luminol-enhanced chemiluminescence. Significant downregulation of selected cytokines (IL-1beta, IL-8, TNF-alfa, IL-6 and IL-10) by LPS stimulated porcine alveolar macrophages and monocyte derived macrophages caused by rEnStef might indicate possible role of E. nipponicum stefin in immunomodulation of the host. |
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