title: Toll-like receptors and aseptic loosening of hip endoprosthesis-a potential to respond against danger signals?
abstract: Bacterial remnants and subclinical biofilms residing on prosthesis surfaces have been speculated to play a role in hip implant loosening by opsonizing otherwise relatively inert wear particles. The innate immune system recognizes these microbial pathogen-associated molecular patterns (PAMPs) using Toll-like receptors (TLRs). Our objective was to evaluate the possible presence of TLRs in aseptic synovial membrane-like interface tissue. Bacterial culture-negative, aseptic (n = 4) periprosthetic synovial membrane-like tissue was compared to osteoarthritis synovial membrane (n = 5) for the presence of cells positive for all known human functional TLRs, stained using specific antibodies by immunohistochemistry, and evaluated using morphometry. In comparison to osteoarthtritic synovium, the number of TLR-positive cells was found to be increased in the aseptic setting, reflecting the considerable macrophage infiltration to the tissues investigated. Thus aseptic periprosthetic tissue seems to be very reactive to PAMPs. It has been recently recognized that TLR do not only respond to traditional PAMPs, but also to endogenous alarmings or danger signals released from necrotic and activated cells. Alarming-TLR interaction in the periprosthetic tissue might be a novel mechanism of aseptic loosening of endoprosthesis.
authors.affiliation: Institute of Clinical Medicine, Department of Medicine, Biomedicum Helsinki, Helsinki University Central Hospital, Helsinki FIN-00029 HUS, Finland.
authors.forename: Tuomas
authors.initials: T
authors.lastname: Lähdeoja
authors.forename: Jukka
authors.initials: J
authors.lastname: Pajarinen
authors.forename: Vesa-Petteri
authors.initials: VP
authors.lastname: Kouri
authors.forename: Tarvo
authors.initials: T
authors.lastname: Sillat
authors.forename: Jari
authors.initials: J
authors.lastname: Salo
authors.forename: Yrjö T
authors.initials: YT
authors.lastname: Konttinen
mesh_terms: D000368:Aged; D000369:Aged, 80 and over; D019644:Arthroplasty, Replacement, Hip / Q000009:adverse effects* / Q000295:instrumentation; D016022:Case-Control Studies; D005260:Female; D005549:Foreign-Body Reaction / Q000209:etiology* / Q000276:immunology*; D006621:Hip Joint / Q000276:immunology / Q000473:pathology / Q000601:surgery; D006622:Hip Prosthesis / Q000009:adverse effects*; D006801:Humans; D008264:Macrophages / Q000276:immunology; D008297:Male; D008875:Middle Aged; D010003:Osteoarthritis / Q000276:immunology / Q000473:pathology / Q000601:surgery; D011475:Prosthesis Failure; D013583:Synovial Membrane / Q000276:immunology / Q000473:pathology; D051193:Toll-Like Receptors / Q000276:immunology*
chemical_list: D051193:Toll-Like Receptors