title: Acanthamoeba Activates Macrophages Predominantly through Toll-Like Receptor 4- and MyD88-Dependent Mechanisms To Induce Interleukin-12 (IL-12) and IL-6.
abstract: Acanthamoeba castellaniiis a ubiquitous free-living amoeba with a worldwide distribution that can occasionally infect humans, causing particularly severe infections in immunocompromised individuals. Dissecting the immunology ofAcanthamoebainfections has been considered problematic due to the very low incidence of disease, despite the high exposure rates. While macrophages are acknowledged as playing a significant role inAcanthamoebainfections, little is known about how this facultative parasite influences macrophage activity. Therefore, in this study we investigated the effects ofAcanthamoebaon the activation of resting macrophages. Consequently, murine bone marrow-derived macrophages were cocultured with trophozoites of either the laboratory Neff strain or a clinical isolate ofA. castellaniiIn vitroreal-time imaging demonstrated that trophozoites of both strains often established evanescent contact with macrophages. BothAcanthamoebastrains induced a proinflammatory macrophage phenotype characterized by the significant production of interleukin-12 (IL-12) and IL-6. However, macrophages cocultured with the clinical isolate ofAcanthamoebaproduced significantly less IL-12 and IL-6 than the Neff strain. The utilization of macrophages derived from MyD88-, TRIF-, Toll-like receptor 2 (TLR2)-, TLR4-, and TLR2/4-deficient mice indicated thatAcanthamoeba-induced proinflammatory cytokine production was through MyD88-dependent, TRIF-independent, TLR4-induced events. This study shows for the first time the involvement of TLRs expressed on macrophages in the recognition of and response toAcanthamoebatrophozoites.
authors.affiliation: Strathclyde Institute of Pharmacy & Biomedical Sciences, University of Strathclyde, Glasgow, United Kingdom.
authors.forename: Antonella
authors.initials: A
authors.lastname: Cano
authors.affiliation: Department of Biomedical Sciences, University of Sassari, Sassari, Italy.
authors.forename: Antonella
authors.initials: A
authors.lastname: Mattana
authors.affiliation: Strathclyde Institute of Pharmacy & Biomedical Sciences, University of Strathclyde, Glasgow, United Kingdom.
authors.forename: Stuart
authors.initials: S
authors.lastname: Woods
authors.affiliation: IBEHR, School of Science & Sport, University of the West of Scotland, Paisley, United Kingdom.
authors.forename: Fiona L
authors.initials: FL
authors.lastname: Henriquez
authors.affiliation: Strathclyde Institute of Pharmacy & Biomedical Sciences, University of Strathclyde, Glasgow, United Kingdom.
authors.forename: James
authors.initials: J
authors.lastname: Alexander
authors.affiliation: Strathclyde Institute of Pharmacy & Biomedical Sciences, University of Strathclyde, Glasgow, United Kingdom c.w.roberts@strath.ac.uk.
authors.forename: Craig W
authors.initials: CW
authors.lastname: Roberts
mesh_terms: D048248:Acanthamoeba castellanii / Q000276:immunology*; D000562:Amebiasis / Q000276:immunology; D000818:Animals; D018664:Interleukin-12 / Q000276:immunology*; D015850:Interleukin-6 / Q000276:immunology*; D008264:Macrophages / Q000276:immunology*; D008297:Male; D051379:Mice; D008807:Mice, Inbred BALB C; D008810:Mice, Inbred C57BL; D018345:Mice, Knockout; D053594:Myeloid Differentiation Factor 88 / Q000235:genetics / Q000378:metabolism*; D015398:Signal Transduction / Q000276:immunology; D051197:Toll-Like Receptor 4 / Q000235:genetics / Q000378:metabolism*
chemical_list: D015850:Interleukin-6; C507780:Myd88 protein, mouse; D053594:Myeloid Differentiation Factor 88; C493487:Tlr4 protein, mouse; D051197:Toll-Like Receptor 4; D018664:Interleukin-12
keywords: Acanthamoeba; macrophages