title: Pleiotropic effects of Blastocystis spp. Subtypes 4 and 7 on ligand-specific toll-like receptor signaling and NF-κB activation in a human monocyte cell line.
abstract: Blastocystis spp. is a common enteric stramenopile parasite that colonizes the colon of hosts of a diverse array of species, including humans. It has been shown to compromise intestinal epithelial cell barrier integrity and mediate the production of pro-inflammatory cytokines and chemokines. Mucosal epithelial surfaces, including the intestinal epithelium, are increasingly recognized to perform a vital surveillance role in the context of innate immunity, through the expression of pathogen recognition receptors, such as Toll-like receptors (TLRs). In this study, we use the human TLR reporter monocytic cell line, THP1-Blue, which expresses all human TLRs, to investigate effects of Blastocystis on TLR activation, more specifically the activation of TLR-2, -4 and -5. We have observed that live Blastocystis spp. parasites and whole cell lysate (WCL) alone do not activate TLRs in THP1-Blue. Live ST4-WR1 parasites inhibited LPS-mediated NF-κB activation in THP1-Blue. In contrast, ST7-B WCL and ST4-WR1 WCL induced pleiotropic modulation of ligand-specific TLR-2 and TLR-4 activation, with no significant effects on flagellin-mediated TLR-5 activation. Real time-qPCR analysis on SEAP reporter gene confirmed the augmenting effect of ST7-B on LPS-mediated NF-κB activation in THP1-Blue. Taken together, this is the first study to characterize interactions between Blastocystis spp. and host TLR activation using an in vitro reporter model.
authors.affiliation: Laboratory of Molecular and Cellular Parasitology, Department of Microbiology, Yong Loo Lin School of Medicine, National University of Singapore, Singapore, Singapore.
authors.forename: Joshua D W
authors.initials: JD
authors.lastname: Teo
authors.affiliation: Laboratory of Molecular and Cellular Parasitology, Department of Microbiology, Yong Loo Lin School of Medicine, National University of Singapore, Singapore, Singapore ; Immunology Program, National University of Singapore, Singapore, Singapore.
authors.forename: Paul A
authors.initials: PA
authors.lastname: Macary
authors.affiliation: Laboratory of Molecular and Cellular Parasitology, Department of Microbiology, Yong Loo Lin School of Medicine, National University of Singapore, Singapore, Singapore.
authors.forename: Kevin S W
authors.initials: KS
authors.lastname: Tan
mesh_terms: D000818:Animals; D016844:Blastocystis / Q000187:drug effects / Q000502:physiology*; D002457:Cell Extracts; D002460:Cell Line; D005408:Flagellin / Q000494:pharmacology; D006358:Hot Temperature; D006801:Humans; D008024:Ligands; D008070:Lipopolysaccharides / Q000494:pharmacology; D009000:Monocytes / Q000187:drug effects / Q000378:metabolism* / Q000469:parasitology*; D016328:NF-kappa B / Q000378:metabolism*; D010271:Parasites / Q000187:drug effects; D015398:Signal Transduction / Q000187:drug effects; D051193:Toll-Like Receptors / Q000378:metabolism*; D015054:Zymosan / Q000494:pharmacology
chemical_list: D002457:Cell Extracts; D008024:Ligands; D008070:Lipopolysaccharides; D016328:NF-kappa B; D051193:Toll-Like Receptors; D005408:Flagellin; D015054:Zymosan