Tick saliva injected into the vertebrate host contains bioactive anti-proteolytic proteins from the cystatin family; however, the molecular basis of their unusual biochemical and physiological properties, distinct from those of host homologs, is unknown. Here, we present Ricistatin, a novel secreted cystatin identified in the salivary gland transcriptome of Ixodes ricinus ticks. Recombinant Ricistatin inhibited host-derived cysteine cathepsins and preferentially targeted endopeptidases, while having only limited impact on proteolysis driven by exopeptidases. Determination of the crystal structure of Ricistatin in complex with a cysteine cathepsin together with characterization of structural determinants in the Ricistatin binding site explained its restricted specificity. Furthermore, Ricistatin was potently immunosuppressive and anti-inflammatory, reducing levels of pro-inflammatory cytokines IL-6, IL-1β, and TNF-α and nitric oxide in macrophages; IL-2 and IL-9 levels in Th9 cells; and OVA antigen-induced CD4+ T cell proliferation and neutrophil migration. This work highlights the immunotherapeutic potential of Ricistatin and, for the first time, provides structural insights into the unique narrow selectivity of tick salivary cystatins determining their bioactivity.

• Klíčová slova
• Cystatins, Host–parasite interactions, Ixodes ricinus, Protease inhibition, Protein structure, Tick saliva,
• MeSH
• cystatiny * farmakologie   MeSH
• cystein metabolismus   MeSH
• endopeptidasy metabolismus   MeSH
• kathepsiny metabolismus   MeSH
• klíště * chemie   MeSH
• obratlovci MeSH
• proteasy metabolismus   MeSH
• slinné cystatiny chemie   MeSH
• zvířata MeSH
• Check Tag
• zvířata MeSH
• Publikační typ
• časopisecké články MeSH
• Názvy látek
• cystatiny * MeSH
• cystein MeSH
• endopeptidasy MeSH
• kathepsiny MeSH
• proteasy MeSH
• slinné cystatiny MeSH

Extracellular vesicles are thought to facilitate pathogen transmission from arthropods to humans and other animals. Here, we reveal that pathogen spreading from arthropods to the mammalian host is multifaceted. Extracellular vesicles from Ixodes scapularis enable tick feeding and promote infection of the mildly virulent rickettsial agent Anaplasma phagocytophilum through the SNARE proteins Vamp33 and Synaptobrevin 2 and dendritic epidermal T cells. However, extracellular vesicles from the tick Dermacentor andersoni mitigate microbial spreading caused by the lethal pathogen Francisella tularensis. Collectively, we establish that tick extracellular vesicles foster distinct outcomes of bacterial infection and assist in vector feeding by acting on skin immunity. Thus, the biology of arthropods should be taken into consideration when developing strategies to control vector-borne diseases.

• MeSH
• Anaplasma phagocytophilum patogenita   MeSH
• bakteriální infekce imunologie   metabolismus   MeSH
• buněčné linie MeSH
• členovci metabolismus   mikrobiologie   fyziologie   MeSH
• Dermacentor metabolismus   mikrobiologie   fyziologie   MeSH
• extracelulární vezikuly metabolismus   ultrastruktura   MeSH
• Francisella tularensis patogenita   MeSH
• genová ontologie MeSH
• intravitální mikroskopie MeSH
• klíšťata metabolismus   mikrobiologie   MeSH
• klíště metabolismus   mikrobiologie   fyziologie   MeSH
• kůže imunologie   mikrobiologie   parazitologie   MeSH
• lidé MeSH
• membránový protein 2 asociovaný s vezikuly metabolismus   MeSH
• myši inbrední C57BL MeSH
• myši knockoutované MeSH
• myši MeSH
• proteiny R-SNARE metabolismus   MeSH
• proteomika MeSH
• T-lymfocyty metabolismus   MeSH
• tandemová hmotnostní spektrometrie MeSH
• transmisní elektronová mikroskopie MeSH
• zánět imunologie   metabolismus   parazitologie   MeSH
• zvířata MeSH
• Check Tag
• lidé MeSH
• mužské pohlaví MeSH
• myši MeSH
• zvířata MeSH
• Publikační typ
• časopisecké články MeSH
• Research Support, N.I.H., Extramural MeSH
• Research Support, U.S. Gov't, Non-P.H.S. MeSH
• Názvy látek
• membránový protein 2 asociovaný s vezikuly MeSH
• proteiny R-SNARE MeSH

Vector-borne diseases cause over 700,000 deaths annually and represent 17% of all infectious illnesses worldwide. This public health menace highlights the importance of understanding how arthropod vectors, microbes and their mammalian hosts interact. Currently, an emphasis of the scientific enterprise is at the vector-host interface where human pathogens are acquired and transmitted. At this spatial junction, arthropod effector molecules are secreted, enabling microbial pathogenesis and disease. Extracellular vesicles manipulate signaling networks by carrying proteins, lipids, carbohydrates and regulatory nucleic acids. Therefore, they are well positioned to aid in cell-to-cell communication and mediate molecular interactions. This Review briefly discusses exosome and microvesicle biogenesis, their cargo, and the role that nanovesicles play during pathogen spread, host colonization and disease pathogenesis. We then focus on the role of extracellular vesicles in dictating microbial pathogenesis and host immunity during transmission of vector-borne pathogens.

• Klíčová slova
• Arthropod-borne disease, Cell communication, Extracellular vesicle, Immunomodulation, Microbial transmission,
• MeSH
• amébiáza parazitologie   přenos   MeSH
• členovci - vektory * mikrobiologie   parazitologie   MeSH
• Culicidae mikrobiologie   parazitologie   MeSH
• exozómy imunologie   mikrobiologie   parazitologie   MeSH
• extracelulární vezikuly * imunologie   mikrobiologie   parazitologie   MeSH
• filarióza parazitologie   přenos   MeSH
• Hemiptera mikrobiologie   parazitologie   MeSH
• imunomodulace MeSH
• infekce přenášené vektorem MeSH
• interakce hostitele a parazita imunologie   fyziologie   MeSH
• leishmanióza parazitologie   přenos   MeSH
• lidé MeSH
• malárie parazitologie   přenos   MeSH
• nemoci přenášené vektory * mikrobiologie   parazitologie   přenos   MeSH
• Psychodidae mikrobiologie   parazitologie   MeSH
• trypanozomiáza parazitologie   přenos   MeSH
• virové nemoci mikrobiologie   přenos   MeSH
• zvířata MeSH
• Check Tag
• lidé MeSH
• zvířata MeSH
• Publikační typ
• časopisecké články MeSH
• přehledy MeSH
• Research Support, N.I.H., Extramural MeSH

The publication of the first tick sialome (salivary gland transcriptome) heralded a new era of research of tick protease inhibitors, which represent important constituents of the proteins secreted via tick saliva into the host. Three major groups of protease inhibitors are secreted into saliva: Kunitz inhibitors, serpins, and cystatins. Kunitz inhibitors are anti-hemostatic agents and tens of proteins with one or more Kunitz domains are known to block host coagulation and/or platelet aggregation. Serpins and cystatins are also anti-hemostatic effectors, but intriguingly, from the translational perspective, also act as pluripotent modulators of the host immune system. Here we focus especially on this latter aspect of protease inhibition by ticks and describe the current knowledge and data on secreted salivary serpins and cystatins and their role in tick-host-pathogen interaction triad. We also discuss the potential therapeutic use of tick protease inhibitors.

• Klíčová slova
• cystatins, immunomodulation, protease inhibitors, serpins, tick-host interaction,
• MeSH
• cystatiny fyziologie   terapeutické užití   MeSH
• imunomodulace MeSH
• inhibitory proteas klasifikace   metabolismus   terapeutické užití   MeSH
• inhibitory serinových proteinas fyziologie   terapeutické užití   MeSH
• interakce hostitele a parazita MeSH
• klíšťata metabolismus   MeSH
• lidé MeSH
• serpiny fyziologie   terapeutické užití   MeSH
• sliny enzymologie   metabolismus   MeSH
• transkriptom MeSH
• zvířata MeSH
• Check Tag
• lidé MeSH
• zvířata MeSH
• Publikační typ
• časopisecké články MeSH
• práce podpořená grantem MeSH
• přehledy MeSH
• Názvy látek
• cystatiny MeSH
• inhibitory proteas MeSH
• inhibitory serinových proteinas MeSH
• serpiny MeSH

Ticks, as obligate hematophagous ectoparasites, impact greatly on animal and human health because they transmit various pathogens worldwide. Over the last decade, several cystatins from different hard and soft ticks were identified and biochemically analyzed for their role in the physiology and blood feeding lifestyle of ticks. All these cystatins are potent inhibitors of papain-like cysteine proteases, but not of legumain. Tick cystatins were either detected in the salivary glands and/or the midgut, key tick organs responsible for blood digestion and the expression of pharmacologically potent salivary proteins for blood feeding. For example, the transcription of two cystatins named HlSC-1 and Sialostatin L2 was highly upregulated in these tick tissues during feeding. Vaccinating hosts against Sialostatin L2 and Om-cystatin 2 as well as silencing of a cystatin gene from Amblyomma americanum significantly inhibited the feeding ability of ticks. Additionally, Om-cystatin 2 and Sialostatin L possessed strong host immunosuppressive properties by inhibiting dendritic cell maturation due to their interaction with cathepsin S. These two cystatins, together with Sialostatin L2 are the first tick cystatins with resolved three-dimensional structure. Sialostatin L, furthermore, showed preventive properties against autoimmune diseases. In the case of the cystatin Hlcyst-2, experimental evidence showed its role in tick innate immunity, since increased Hlcyst-2 transcript levels were detected in Babesia gibsoni-infected larval ticks and the protein inhibited Babesia growth. Other cystatins, such as Hlcyst-1 or Om-cystatin 2 are assumed to be involved in regulating blood digestion. Only for Bmcystatin was a role in tick embryogenesis suggested. Finally, all the biochemically analyzed tick cystatins are powerful protease inhibitors, and some may be novel antigens for developing anti-tick vaccines and drugs of medical importance due to their stringent target specificity.

• MeSH
• cystatiny farmakologie   MeSH
• inhibitory cysteinových proteinas farmakologie   MeSH
• klíšťata účinky léků   fyziologie   MeSH
• lidé MeSH
• molekulární modely MeSH
• molekulární sekvence - údaje MeSH
• sekvence aminokyselin MeSH
• sekvenční seřazení MeSH
• stravovací zvyklosti účinky léků   MeSH
• zvířata MeSH
• Check Tag
• lidé MeSH
• zvířata MeSH
• Publikační typ
• časopisecké články MeSH
• práce podpořená grantem MeSH
• přehledy MeSH
• Research Support, N.I.H., Extramural MeSH
• Názvy látek
• cystatiny MeSH
• inhibitory cysteinových proteinas MeSH

The saliva of blood-feeding parasites is a rich source of peptidase inhibitors that help to overcome the host's defence during host-parasite interactions. Using proteomic analysis, the cystatin OmC2 was demonstrated in the saliva of the soft tick Ornithodoros moubata, an important disease vector transmitting African swine fever virus and the spirochaete Borrelia duttoni. A structural, biochemical and biological characterization of this peptidase inhibitor was undertaken in the present study. Recombinant OmC2 was screened against a panel of physiologically relevant peptidases and was found to be an effective broad-specificity inhibitor of cysteine cathepsins, including endopeptidases (cathepsins L and S) and exopeptidases (cathepsins B, C and H). The crystal structure of OmC2 was determined at a resolution of 2.45 A (1 A=0.1 nm) and was used to describe the structure-inhibitory activity relationship. The biological impact of OmC2 was demonstrated both in vitro and in vivo. OmC2 affected the function of antigen-presenting mouse dendritic cells by reducing the production of the pro-inflammatory cytokines tumour necrosis factor alpha and interleukin-12, and proliferation of antigen-specific CD4+ T-cells. This suggests that OmC2 may suppress the host's adaptive immune response. Immunization of mice with OmC2 significantly suppressed the survival of O. moubata in infestation experiments. We conclude that OmC2 is a promising target for the development of a novel anti-tick vaccine to control O. moubata populations and combat the spread of associated diseases.

• MeSH
• imunologické faktory chemie   fyziologie   MeSH
• krystalizace MeSH
• krystalografie rentgenová MeSH
• molekulární sekvence - údaje MeSH
• myši inbrední C3H MeSH
• myši inbrední C57BL MeSH
• myši transgenní MeSH
• myši MeSH
• Ornithodoros chemie   imunologie   MeSH
• sekvence aminokyselin MeSH
• slinné cystatiny chemie   fyziologie   MeSH
• zvířata MeSH
• Check Tag
• myši MeSH
• ženské pohlaví MeSH
• zvířata MeSH
• Publikační typ
• časopisecké články MeSH
• práce podpořená grantem MeSH
• srovnávací studie MeSH
• Názvy látek
• imunologické faktory MeSH
• slinné cystatiny MeSH