Kunitz domain-containing proteins are ubiquitous serine protease inhibitors with promising therapeutic potential. They target key proteases involved in major cellular processes such as inflammation or hemostasis through competitive inhibition in a substrate-like manner. Protease inhibitors from the Kunitz superfamily have a low molecular weight (18-24 kDa) and are characterized by the presence of one or more Kunitz motifs consisting of α-helices and antiparallel β-sheets stabilized by three disulfide bonds. Kunitz-type inhibitors are an important fraction of the protease inhibitors found in tick saliva. Their roles in inhibiting and/or suppressing host homeostatic responses continue to be shown to be additive or synergistic with other protease inhibitors such as cystatins or serpins, ultimately mediating successful blood feeding for the tick. In this review, we discuss the biochemical features of tick salivary Kunitz-type protease inhibitors. We focus on their various effects on host hemostasis and immunity at the molecular and cellular level and their potential therapeutic applications. In doing so, we highlight that their pharmacological properties can be exploited for the development of novel therapies and vaccines.

• Klíčová slova
• Kunitz-type, hemostasis, immunomodulation, parasite-host interactions, protease inhibitors, ticks,
• MeSH
• cystatiny * metabolismus   MeSH
• inhibitory serinových proteinas farmakologie   terapeutické užití   metabolismus   MeSH
• klíšťata * MeSH
• serpiny * metabolismus   MeSH
• sliny metabolismus   MeSH
• zvířata MeSH
• Check Tag
• zvířata MeSH
• Publikační typ
• časopisecké články MeSH
• přehledy MeSH
• Názvy látek
• cystatiny * MeSH
• inhibitory serinových proteinas MeSH
• serpiny * MeSH

The last three decades of research into tick salivary components have revealed several proteins with important pharmacological and immunological activities. Two primary interests have driven research into tick salivary secretions: the search for suitable pathogen transmission blocking or "anti-tick" vaccine candidates and the search for novel therapeutics derived from tick salivary components. Intensive basic research in the field of tick salivary gland transcriptomics and proteomics has identified several major protein families that play important roles in tick feeding and overcoming vertebrate anti-tick responses. Moreover, these families contain members with unrealized therapeutic potential. Here we review the major tick salivary protein families exploitable in medical applications such as immunomodulation, inhibition of hemostasis and inflammation. Moreover, we discuss the potential, opportunities, and challenges in searching for novel tick-derived drugs.

• Klíčová slova
• anti-inflammatory proteins, hemostasis, immunomodulation, salivary proteins, therapeutics, ticks,
• Publikační typ
• časopisecké články MeSH
• přehledy MeSH

BACKGROUND: Ticks are blood-sucking arthropods and a primary function of tick salivary proteins is to counteract the host's immune response. Tick salivary Kunitz-domain proteins perform multiple functions within the feeding lesion and have been classified as venoms; thereby, constituting them as one of the important elements in the arms race with the host. The two main mechanisms advocated to explain the functional heterogeneity of tick salivary Kunitz-domain proteins are gene sharing and gene duplication. Both do not, however, elucidate the evolution of the Kunitz family in ticks from a structural dynamic point of view. The Red Queen hypothesis offers a fruitful theoretical framework to give a dynamic explanation for host-parasite interactions. Using the recent salivary gland Ixodes ricinus transcriptome we analyze, for the first time, single Kunitz-domain encoding transcripts by means of computational, structural bioinformatics and phylogenetic approaches to improve our understanding of the structural evolution of this important multigenic protein family. RESULTS: Organizing the I. ricinus single Kunitz-domain peptides based on their cysteine motif allowed us to specify a putative target and to relate this target specificity to Illumina transcript reads during tick feeding. We observe that several of these Kunitz peptide groups vary in their translated amino acid sequence, secondary structure, antigenicity, and intrinsic disorder, and that the majority of these groups are subject to a purifying (negative) selection. We finalize by describing the evolution and emergence of these Kunitz peptides. The overall interpretation of our analyses discloses a rapidly emerging Kunitz group with a distinct disulfide bond pattern from the I. ricinus salivary gland transcriptome. CONCLUSIONS: We propose a model to explain the structural and functional evolution of tick salivary Kunitz peptides that we call target-oriented evolution. Our study reveals that combining analytical approaches (transcriptomes, computational, bioinformatics and phylogenetics) improves our understanding of the biological functions of important salivary gland mediators during tick feeding.

• MeSH
• fylogeneze MeSH
• klíště chemie   klasifikace   genetika   metabolismus   MeSH
• molekulární evoluce * MeSH
• proteiny členovců chemie   genetika   metabolismus   MeSH
• sekvence aminokyselin MeSH
• sekvenční seřazení MeSH
• slinné proteiny a peptidy chemie   genetika   metabolismus   MeSH
• terciární struktura proteinů MeSH
• transkriptom * MeSH
• výpočetní biologie MeSH
• zvířata MeSH
• Check Tag
• ženské pohlaví MeSH
• zvířata MeSH
• Publikační typ
• časopisecké články MeSH
• práce podpořená grantem MeSH
• Názvy látek
• proteiny členovců MeSH
• slinné proteiny a peptidy MeSH

BACKGROUND: A salivary proteome-transcriptome project on the hard tick Ixodes scapularis revealed that Kunitz peptides are the most abundant salivary proteins. Ticks use Kunitz peptides (among other salivary proteins) to combat host defense mechanisms and to obtain a blood meal. Most of these Kunitz peptides, however, remain functionally uncharacterized, thus limiting our knowledge about their biochemical interactions. RESULTS: We discovered an unusual cysteine motif in a Kunitz peptide. This peptide inhibits several serine proteases with high affinity and was named tryptogalinin due to its high affinity for β-tryptase. Compared with other functionally described peptides from the Acari subclass, we showed that tryptogalinin is phylogenetically related to a Kunitz peptide from Rhipicephalus appendiculatus, also reported to have a high affinity for β-tryptase. Using homology-based modeling (and other protein prediction programs) we were able to model and explain the multifaceted function of tryptogalinin. The N-terminus of the modeled tryptogalinin is detached from the rest of the peptide and exhibits intrinsic disorder allowing an increased flexibility for its high affinity with its inhibiting partners (i.e., serine proteases). CONCLUSIONS: By incorporating experimental and computational methods our data not only describes the function of a Kunitz peptide from Ixodes scapularis, but also allows us to hypothesize about the molecular basis of this function at the atomic level.

• MeSH
• aminokyselinové motivy MeSH
• cystein chemie   genetika   MeSH
• fylogeneze MeSH
• inhibitory serinových proteinas chemie   klasifikace   genetika   metabolismus   MeSH
• klíště chemie   genetika   metabolismus   MeSH
• lidé MeSH
• molekulární modely MeSH
• molekulární sekvence - údaje MeSH
• proteiny členovců chemie   klasifikace   genetika   metabolismus   MeSH
• rekombinantní proteiny chemie   klasifikace   genetika   metabolismus   MeSH
• Rhipicephalus chemie   genetika   metabolismus   MeSH
• sekvenční homologie aminokyselin MeSH
• slinné proteiny a peptidy chemie   klasifikace   genetika   metabolismus   MeSH
• terciární struktura proteinů MeSH
• tryptasy antagonisté a inhibitory   chemie   metabolismus   MeSH
• zvířata MeSH
• Check Tag
• lidé MeSH
• zvířata MeSH
• Publikační typ
• časopisecké články MeSH
• práce podpořená grantem MeSH
• Názvy látek
• cystein MeSH
• inhibitory serinových proteinas MeSH
• proteiny členovců MeSH
• rekombinantní proteiny MeSH
• slinné proteiny a peptidy MeSH
• tryptasy MeSH

When feeding on vertebrate host ticks (ectoparasitic arthropods and potential vectors of bacterial, rickettsial, protozoal, and viral diseases) induce both innate and specific acquired host-immune reactions as part of anti-tick defenses. In a resistant host immune defense can lead to reduced tick viability, sometimes resulting in tick death. Tick responds to the host immune attack by secreting saliva containing pharmacologically active molecules and modulating host immune response. Tick saliva-effected immunomodulation at the attachment site facilitates both tick feeding and enhances the success of transmission of pathogens from tick into the host. On the other hand, host immunization with antigens from tick saliva can induce anti-tick resistance and is seen to be able to induce immunity against pathogens transmitted by ticks. Many pharmacological properties of saliva described in ticks are shared widely among other blood-feeding arthropods.

• MeSH
• arachnida jako vektory MeSH
• imunita účinky léků   MeSH
• infestace klíšťaty imunologie   MeSH
• interakce hostitele a parazita účinky léků   imunologie   MeSH
• klíšťata chemie   imunologie   mikrobiologie   MeSH
• nemoci přenášené klíšťaty imunologie   přenos   MeSH
• slinné proteiny a peptidy farmakologie   MeSH
• slinné žlázy fyziologie   MeSH
• zvířata MeSH
• Check Tag
• zvířata MeSH
• Publikační typ
• časopisecké články MeSH
• práce podpořená grantem MeSH
• přehledy MeSH
• Názvy látek
• slinné proteiny a peptidy MeSH