title: Activation of TLR2 and TLR4 by glycosylphosphatidylinositols derived from Toxoplasma gondii.
abstract: GPIs isolated from Toxoplasma gondii, as well as a chemically synthesized GPI lacking the lipid moiety, activated a reporter gene in Chinese hamster ovary cells expressing TLR4, while the core glycan and lipid moieties cleaved from the GPIs activated both TLR4- and TLR2-expressing cells. MyD88, but not TLR2, TLR4, or CD14, is absolutely needed to trigger TNF-alpha production by macrophages exposed to T. gondii GPIs. Importantly, TNF-alpha response to GPIs was completely abrogated in macrophages from TLR2/4-double-deficient mice. MyD88(-/-) mice were more susceptible to death than wild-type (WT), TLR2(-/-), TLR4(-/-), TLR2/4(-/-), and CD14(-/-) mice infected with the ME-49 strain of T. gondii. The cyst number was higher in the brain of TLR2/4(-/-), but not TLR2(-/-), TLR4(-/-), and CD14(-/-), mice, as compared with WT mice. Upon infection with the ME-49 strain of T. gondii, we observed no decrease of IL-12 and IFN-gamma production in TLR2-, TLR4-, or CD14-deficient mice. Indeed, splenocytes from T. gondii-infected TLR2(-/-) and TLR2/4(-/-) mice produced more IFN-gamma than cells from WT mice in response to in vitro stimulation with parasite extracts enriched in GPI-linked surface proteins. Together, our results suggest that both TLR2 and TLR4 receptors may participate in the host defense against T. gondii infection through their activation by the GPIs and could work together with other MyD88-dependent receptors, like other TLRs or even IL-18R or IL-1R, to obtain an effective host response against T. gondii infection.
authors.affiliation: Institut für Virologie, AG Parasitologie, Philipps University, Marburg, Germany. debierre@staff.uni-marburg.de
authors.forename: Françoise
authors.initials: F
authors.lastname: Debierre-Grockiego
authors.forename: Marco A
authors.initials: MA
authors.lastname: Campos
authors.forename: Nahid
authors.initials: N
authors.lastname: Azzouz
authors.forename: Jörg
authors.initials: J
authors.lastname: Schmidt
authors.forename: Ulrike
authors.initials: U
authors.lastname: Bieker
authors.forename: Marianne Garcia
authors.initials: MG
authors.lastname: Resende
authors.forename: Daniel Santos
authors.initials: DS
authors.lastname: Mansur
authors.forename: Ralf
authors.initials: R
authors.lastname: Weingart
authors.forename: Richard R
authors.initials: RR
authors.lastname: Schmidt
authors.forename: Douglas T
authors.initials: DT
authors.lastname: Golenbock
authors.forename: Ricardo T
authors.initials: RT
authors.lastname: Gazzinelli
authors.forename: Ralph T
authors.initials: RT
authors.lastname: Schwarz
mesh_terms: D000818:Animals; D016466:CHO Cells; D006224:Cricetinae; D003412:Cricetulus; D005434:Flow Cytometry; D017261:Glycosylphosphatidylinositols / Q000737:chemistry / Q000276:immunology / Q000378:metabolism*; D018950:Lipopolysaccharide Receptors / Q000276:immunology / Q000378:metabolism; D008264:Macrophages / Q000276:immunology / Q000378:metabolism; D008297:Male; D051379:Mice; D018345:Mice, Knockout; D053594:Myeloid Differentiation Factor 88 / Q000276:immunology / Q000378:metabolism; D051195:Toll-Like Receptor 2 / Q000276:immunology / Q000378:metabolism*; D051197:Toll-Like Receptor 4 / Q000276:immunology / Q000378:metabolism*; D014122:Toxoplasma / Q000276:immunology; D014124:Toxoplasmosis, Animal / Q000276:immunology*
chemical_list: D017261:Glycosylphosphatidylinositols; D018950:Lipopolysaccharide Receptors; C507780:Myd88 protein, mouse; D053594:Myeloid Differentiation Factor 88; C495345:TLR4 protein, human; C493486:Tlr2 protein, mouse; D051195:Toll-Like Receptor 2; D051197:Toll-Like Receptor 4