Most cited article - PubMed ID 36675071
Tick Salivary Kunitz-Type Inhibitors: Targeting Host Hemostasis and Immunity to Mediate Successful Blood Feeding
INTRODUCTION: The Neotropical tick Amblyomma sculptum is the primary vector of Rickettsia rickettsii, the causative agent of Brazilian spotted fever, a disease associated with high fatality rates. Tick saliva, a complex mixture of bioactive molecules essential for successful blood feeding, facilitates pathogen transmission and modulates host immune responses. A comprehensive evaluation of the salivary gland transcriptome database reveals that protease inhibitors are abundantly expressed molecules in tick saliva during feeding. Thus, this study aims to describe and characterize the most expressed member of the cystatin family identified in Amblyomma sculptum salivary transcriptome, named Amblyostatin-1. METHODS: Bioinformatic tools were employed for in silico analysis of the Amblyostatin-1 sequence and structure. A recombinant version of Amblyostatin-1 was expressed in an Escherichia coli system, evaluated against a panel of cysteine proteases in biochemical assays, and used to generate antibodies in immunized mice. The biological activities of Amblyostatin-1 were assessed by its effects on dendritic cell maturation in vitro and in a carrageenan-induced inflammation model in vivo. RESULTS: Based on its sequence and predicted three-dimensional structure, Amblyostatin-1 is classified as an I25B cystatin, and its recombinant form selectively inhibits cathepsins L, C, and S at different rates, with a low nanomolar Ki value of 0.697 ± 0.22 nM against cathepsin L. Regarding its biological activities, recombinant Amblyostatin-1 partially affects LPS-induced dendritic cell maturation by downmodulating the costimulatory molecules CD80 and CD86 at higher micromolar concentrations (3 µM) while promoting IL-10 production at nanomolar concentrations (100 nM). The apparent lack of Amblyostatin-1-specific antibody responses in immunized mice suggests an impairment of antigen processing and presentation in vivo. Furthermore, in a carrageenan-induced inflammation model, Amblyostatin-1 decreased edema formation and neutrophil infiltration into the skin without affecting other myeloid cells. DISCUSSION: These findings establish Amblyostatin-1 as a novel salivary cystatin with immunomodulatory and anti-inflammatory properties, highlighting its potential as an immunobiological agent.
- Keywords
- Amblyomma sculptum, Amblyostatin-1, immunomodulation, inflammation, tick saliva, tick-host interaction,
- MeSH
- Amblyomma * immunology metabolism MeSH
- Anti-Inflammatory Agents * pharmacology MeSH
- Arachnid Vectors * immunology MeSH
- Cystatins * immunology MeSH
- Dendritic Cells immunology drug effects MeSH
- Mice MeSH
- Arthropod Proteins * genetics immunology MeSH
- Salivary Cystatins * genetics immunology pharmacology chemistry metabolism MeSH
- Animals MeSH
- Check Tag
- Mice MeSH
- Female MeSH
- Animals MeSH
- Publication type
- Journal Article MeSH
- Names of Substances
- Anti-Inflammatory Agents * MeSH
- Cystatins * MeSH
- Arthropod Proteins * MeSH
- Salivary Cystatins * MeSH
BACKGROUND: Ticks, hematophagous Acari, pose a significant threat by transmitting various pathogens to their vertebrate hosts during feeding. Despite advances in tick genomics, high-quality genomes were lacking until recently, particularly in the genus Ixodes, which includes the main vectors of Lyme disease. RESULTS: Here, we present the genome sequences of four tick species, derived from a single female individual, with a particular focus on the European species Ixodes ricinus, achieving a chromosome-level assembly. Additionally, draft assemblies were generated for the three other Ixodes species, I. persulcatus, I. pacificus, and I. hexagonus. The quality of the four genomes and extensive annotation of several important gene families have allowed us to study the evolution of gene repertoires at the level of the genus Ixodes and of the tick group. We have determined gene families that have undergone major amplifications during the evolution of ticks, while an expression atlas obtained for I. ricinus reveals striking patterns of specialization both between and within gene families. Notably, several gene family amplifications are associated with a proliferation of single-exon genes-most strikingly for fatty acid elongases and sulfotransferases. CONCLUSIONS: The integration of our data with existing genomes establishes a solid framework for the study of gene evolution, improving our understanding of tick biology. In addition, our work lays the foundations for applied research and innovative control targeting these organisms.
- Keywords
- Comparative genomics, Duplication, Hematophagy, Parasite, Retroposition,
- MeSH
- Biological Evolution * MeSH
- Phylogeny MeSH
- Genome * MeSH
- Ixodes * genetics classification MeSH
- Evolution, Molecular * MeSH
- Animals MeSH
- Check Tag
- Female MeSH
- Animals MeSH
- Publication type
- Journal Article MeSH
Protease inhibitors regulate various biological processes and prevent host tissue/organ damage. Specific inhibition/regulation of proteases is clinically valuable for treating several diseases. Psoriasis affects the skin in the limbs and scalp of the body, and the contribution of cysteine and serine proteases to the development of skin inflammation is well documented. Cysteine protease inhibitors from ticks have high specificity, selectivity, and affinity to their target proteases and are efficient immunomodulators. However, their potential therapeutic effect on psoriasis pathogenesis remains to be determined. Therefore, we tested four tick cystatins (Sialostatin L, Sialostatin L2, Iristatin, and Mialostatin) in the recently developed, innate immunity-dependent mannan-induced psoriasis model. We explored the effects of protease inhibitors on clinical symptoms and histological features. In addition, the number and percentage of immune cells (dendritic cells, neutrophils, macrophages, and γδT cells) by flow cytometry, immunofluorescence/immunohistochemistry and, the expression of pro-inflammatory cytokines (TNF-a, IL-6, IL-22, IL-23, and IL-17 family) by qPCR were analyzed using skin, spleen, and lymph node samples. Tick protease inhibitors have significantly decreased psoriasis symptoms and disease manifestations but had differential effects on inflammatory responses and immune cell populations, suggesting different modes of action of these inhibitors on psoriasis-like inflammation. Thus, our study demonstrates, for the first time, the usefulness of tick-derived protease inhibitors for treating skin inflammation in patients.
- Keywords
- autoimmune disease, immune responses, protease inhibitors, psoriasis, tick,
- MeSH
- Dermatitis * MeSH
- Endopeptidases MeSH
- Cysteine Proteinase Inhibitors MeSH
- Protease Inhibitors MeSH
- Humans MeSH
- Mannans MeSH
- Immunity, Innate MeSH
- Peptide Hydrolases MeSH
- Psoriasis * chemically induced drug therapy MeSH
- Inflammation drug therapy MeSH
- Check Tag
- Humans MeSH
- Publication type
- Journal Article MeSH
- Research Support, Non-U.S. Gov't MeSH
- Names of Substances
- Endopeptidases MeSH
- Cysteine Proteinase Inhibitors MeSH
- Protease Inhibitors MeSH
- Mannans MeSH
- Peptide Hydrolases MeSH
Arthropod disease vectors not only transmit malaria but many other serious diseases, many of which are, to a greater or lesser degree, neglected [...].
