A novel Kunitz protein with proposed dual function from Eudiplozoon nipponicum (Monogenea) impairs haemostasis and action of complement in vitro
Language English Country England, Great Britain Media print-electronic
Document type Journal Article, Research Support, Non-U.S. Gov't
PubMed
30796952
DOI
10.1016/j.ijpara.2018.11.010
PII: S0020-7519(19)30026-8
Knihovny.cz E-resources
- Keywords
- Anticoagulant, Diplozoidae, Factor X, Haematophagy, Helminth, Kunitz, Peptidase inhibitor, Plasmin,
- MeSH
- Antifibrinolytic Agents chemistry immunology MeSH
- Anticoagulants chemistry immunology MeSH
- Factor Xa immunology MeSH
- Hemostasis * MeSH
- Trematode Infections blood immunology parasitology veterinary MeSH
- Enzyme Inhibitors chemistry immunology MeSH
- Factor Xa Inhibitors chemistry immunology MeSH
- Host-Parasite Interactions MeSH
- Carps blood immunology parasitology MeSH
- Complement System Proteins immunology MeSH
- Fish Diseases blood immunology parasitology MeSH
- Fibrinolysin immunology MeSH
- Plasma Kallikrein antagonists & inhibitors immunology MeSH
- Helminth Proteins chemistry genetics immunology MeSH
- Amino Acid Sequence MeSH
- Sequence Alignment MeSH
- Trematoda chemistry genetics immunology MeSH
- Animals MeSH
- Check Tag
- Animals MeSH
- Publication type
- Journal Article MeSH
- Research Support, Non-U.S. Gov't MeSH
- Names of Substances
- Antifibrinolytic Agents MeSH
- Anticoagulants MeSH
- Factor Xa MeSH
- Enzyme Inhibitors MeSH
- Factor Xa Inhibitors MeSH
- Complement System Proteins MeSH
- Fibrinolysin MeSH
- Plasma Kallikrein MeSH
- Helminth Proteins MeSH
Serine peptidases are involved in many physiological processes including digestion, haemostasis and complement cascade. Parasites regulate activities of host serine peptidases to their own benefit, employing various inhibitors, many of which belong to the Kunitz-type protein family. In this study, we confirmed the presence of potential anticoagulants in protein extracts of the haematophagous monogenean Eudiplozoon nipponicum which parasitizes the common carp. We then focused on a Kunitz protein (EnKT1) discovered in the E. nipponicum transcriptome, which structurally resembles textilinin-1, an antihemorrhagic snake venom factor from Pseudonaja textilis. The protein was recombinantly expressed, purified and biochemically characterised. The recombinant EnKT1 did inhibit in vitro activity of Factor Xa of the coagulation cascade, but exhibited a higher activity against plasmin and plasma kallikrein, which participate in fibrinolysis, production of kinins, and complement activation. Anti-coagulation properties of EnKT1 based on the inhibition of Factor Xa were confirmed by thromboelastography, but no effect on fibrinolysis was observed. Moreover, we discovered that EnKT1 significantly impairs the function of fish complement, possibly by inhibiting plasmin or Factor Xa which can act as a C3 and C5 convertase. We localised Enkt1 transcripts and protein within haematin digestive cells of the parasite by RNA in situ hybridisation and immunohistochemistry, respectively. Based on these results, we suggest that the secretory Kunitz protein of E. nipponicum has a dual function. In particular, it impairs both haemostasis and complement activation in vitro, and thus might facilitate digestion of a host's blood and protect a parasite's gastrodermis from damage by the complement. This study presents, to our knowledge, the first characterisation of a Kunitz protein from monogeneans and the first example of a parasite Kunitz inhibitor that impairs the function of the complement.
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