title: PTX3 function as an opsonin for the dectin-1-dependent internalization of zymosan by macrophages.
abstract: Pentraxin 3 (PTX3) is a tumor necrosis factor and interleukin-1beta-stimulated gene that encodes a long PTX with proinflammatory activity. Here, we show that peritoneal macrophages derived from PTX3 transgenic (Tg) mice express higher levels of PTX3 mRNA than macrophages from wild-type (WT) mice, at basal level as well as upon stimulation with zymosan (Zy). Macrophages from Tg mice also showed improved opsonin-independent phagocytosis of Zy particles and the yeast form of the fungus Paracoccidioides brasiliensis. In the case of P. brasiliensis, an enhanced microbicidal activity accompanied by higher production of nitric oxide was also observed in macrophages from Tg mice. Using fluorescein-activated cell sorter analysis and reverse transcriptase-polymerase chain reaction, we demonstrated that basal level of Toll-like receptor-6 and Zy-induced dectin-1 expression was slightly but consistently higher in macrophages from Tg mice than in macrophages from WT mice. Recombinant (r)PTX3 protein binds to Zy particles as well as to yeast cells of P. brasiliensis and addition of rPTX3, to a culture of WT-derived macrophages containing Zy leads to an increase in the phagocytic index, which parallels that of Tg-derived macrophages, demonstrating the opsonin-like activity of PTX3. It is important that blockade of dectin-1 receptor inhibited the phagocytosis of Zy particles by WT and PTX3 Tg macrophages, pointing out the relevant role of dectin-1 as the main receptor involved in Zy uptake. Our results provide evidence for a role of PTX3 as an important component of the innate-immune response and as part of the host mechanisms that control fungal recognition and phagocytosis.
authors.affiliation: Ludwig Institute for Cancer Research, São Paulo, Brazil.
authors.forename: S N
authors.initials: SN
authors.lastname: Diniz
authors.forename: R
authors.initials: R
authors.lastname: Nomizo
authors.forename: P S
authors.initials: PS
authors.lastname: Cisalpino
authors.forename: M M
authors.initials: MM
authors.lastname: Teixeira
authors.forename: G D
authors.initials: GD
authors.lastname: Brown
authors.forename: A
authors.initials: A
authors.lastname: Mantovani
authors.forename: S
authors.initials: S
authors.lastname: Gordon
authors.forename: L F L
authors.initials: LF
authors.lastname: Reis
authors.forename: A A M
authors.initials: AA
authors.lastname: Dias
mesh_terms: D000818:Animals; D001665:Binding Sites / Q000187:drug effects / Q000235:genetics; D002097:C-Reactive Protein / Q000235:genetics* / Q000378:metabolism; D005260:Female; D007113:Immunity, Innate / Q000235:genetics; D037181:Lectins, C-Type; D017737:Macrophages, Peritoneal / Q000187:drug effects / Q000276:immunology / Q000378:metabolism*; D008297:Male; D008562:Membrane Glycoproteins / Q000187:drug effects / Q000378:metabolism; D008565:Membrane Proteins / Q000037:antagonists & inhibitors / Q000378:metabolism*; D051379:Mice; D008822:Mice, Transgenic; D009419:Nerve Tissue Proteins / Q000037:antagonists & inhibitors / Q000378:metabolism*; D009569:Nitric Oxide / Q000378:metabolism; D009895:Opsonin Proteins / Q000235:genetics* / Q000378:metabolism; D010228:Paracoccidioides / Q000276:immunology; D010587:Phagocytosis / Q000187:drug effects / Q000235:genetics* / Q000276:immunology; D012333:RNA, Messenger / Q000187:drug effects / Q000378:metabolism; D011956:Receptors, Cell Surface / Q000187:drug effects / Q000378:metabolism; D011993:Recombinant Fusion Proteins / Q000378:metabolism; D000683:Serum Amyloid P-Component / Q000235:genetics* / Q000378:metabolism; D051216:Toll-Like Receptor 6; D015054:Zymosan / Q000276:immunology* / Q000378:metabolism / Q000494:pharmacology; D000099153:Pentraxins; D000099181:Dectin-1
chemical_list: D002097:C-Reactive Protein; D037181:Lectins, C-Type; D008562:Membrane Glycoproteins; D008565:Membrane Proteins; D009419:Nerve Tissue Proteins; D009569:Nitric Oxide; D009895:Opsonin Proteins; D012333:RNA, Messenger; D011956:Receptors, Cell Surface; D011993:Recombinant Fusion Proteins; D000683:Serum Amyloid P-Component; D051216:Toll-Like Receptor 6; D015054:Zymosan; D000099153:Pentraxins; D000099181:Dectin-1; C495369:Tlr6 protein, mouse