title: Novel immunomodulators from hard ticks selectively reprogramme human dendritic cell responses.
abstract: Hard ticks subvert the immune responses of their vertebrate hosts in order to feed for much longer periods than other blood-feeding ectoparasites; this may be one reason why they transmit perhaps the greatest diversity of pathogens of any arthropod vector. Tick-induced immunomodulation is mediated by salivary components, some of which neutralise elements of innate immunity or inhibit the development of adaptive immunity. As dendritic cells (DC) trigger and help to regulate adaptive immunity, they are an ideal target for immunomodulation. However, previously described immunoactive components of tick saliva are either highly promiscuous in their cellular and molecular targets or have limited effects on DC. Here we address the question of whether the largest and globally most important group of ticks (the ixodid metastriates) produce salivary molecules that specifically modulate DC activity. We used chromatography to isolate a salivary gland protein (Japanin) from Rhipicephalus appendiculatus ticks. Japanin was cloned, and recombinant protein was produced in a baculoviral expression system. We found that Japanin specifically reprogrammes DC responses to a wide variety of stimuli in vitro, radically altering their expression of co-stimulatory and co-inhibitory transmembrane molecules (measured by flow cytometry) and their secretion of pro-inflammatory, anti-inflammatory and T cell polarising cytokines (assessed by Luminex multiplex assays); it also inhibits the differentiation of DC from monocytes. Sequence alignments and enzymatic deglycosylation revealed Japanin to be a 17.7 kDa, N-glycosylated lipocalin. Using molecular cloning and database searches, we have identified a group of homologous proteins in R. appendiculatus and related species, three of which we have expressed and shown to possess DC-modulatory activity. All data were obtained using DC generated from at least four human blood donors, with rigorous statistical analysis. Our results suggest a previously unknown mechanism for parasite-induced subversion of adaptive immunity, one which may also facilitate pathogen transmission.
authors.affiliation: Nuffield Department of Surgical Sciences, University of Oxford, John Radcliffe Hospital, Oxford, United Kingdom.
authors.forename: Stephen G
authors.initials: SG
authors.lastname: Preston
authors.forename: Juraj
authors.initials: J
authors.lastname: Majtán
authors.forename: Chrisoula
authors.initials: C
authors.lastname: Kouremenou
authors.forename: Oliwia
authors.initials: O
authors.lastname: Rysnik
authors.forename: Lena F
authors.initials: LF
authors.lastname: Burger
authors.forename: Alejandro
authors.initials: A
authors.lastname: Cabezas Cruz
authors.forename: Maylin
authors.initials: M
authors.lastname: Chiong Guzman
authors.forename: Miles A
authors.initials: MA
authors.lastname: Nunn
authors.forename: Guido C
authors.initials: GC
authors.lastname: Paesen
authors.forename: Patricia A
authors.initials: PA
authors.lastname: Nuttall
authors.forename: Jonathan M
authors.initials: JM
authors.lastname: Austyn
mesh_terms: D056704:Adaptive Immunity / Q000187:drug effects / Q000235:genetics / Q000276:immunology; D000818:Animals; D060829:Arthropod Proteins / Q000235:genetics / Q000276:immunology* / Q000494:pharmacology; D002454:Cell Differentiation / Q000187:drug effects / Q000235:genetics / Q000276:immunology; D002460:Cell Line; D016207:Cytokines / Q000235:genetics / Q000276:immunology; D003713:Dendritic Cells / Q000276:immunology* / Q000473:pathology; D005786:Gene Expression Regulation / Q000187:drug effects / Q000235:genetics / Q000276:immunology; D006801:Humans; D007155:Immunologic Factors / Q000235:genetics / Q000276:immunology* / Q000494:pharmacology; D009000:Monocytes / Q000276:immunology* / Q000473:pathology; D011994:Recombinant Proteins / Q000235:genetics / Q000276:immunology / Q000494:pharmacology; D048494:Rhipicephalus / Q000235:genetics / Q000276:immunology*; D012471:Salivary Proteins and Peptides / Q000235:genetics / Q000276:immunology* / Q000494:pharmacology
chemical_list: D060829:Arthropod Proteins; D016207:Cytokines; D007155:Immunologic Factors; D011994:Recombinant Proteins; D012471:Salivary Proteins and Peptides