title: Soluble immune complexes shift the TLR-induced cytokine production of distinct polarized human macrophage subsets towards IL-10.
abstract: BACKGROUND
  Costimulation of murine macrophages with immune complexes (ICs) and TLR ligands leads to alternative activation. Studies on human myeloid cells, however, indicate that ICs induce an increased pro-inflammatory cytokine production. This study aimed to clarify the effect of ICs on the pro- versus anti-inflammatory profile of human polarized macrophages.
  
  
  METHODS
  Monocytes isolated from peripheral blood of healthy donors were polarized for four days with IFN-γ, IL-4, IL-10, GM-CSF, M-CSF, or LPS, in the presence or absence of heat aggregated gamma-globulins (HAGGs). Phenotypic polarization markers were measured by flow cytometry. Polarized macrophages were stimulated with HAGGs or immobilized IgG alone or in combination with TLR ligands. TNF, IL-6, IL-10, IL-12, and IL-23 were measured by Luminex and/or RT-qPCR.
  
  
  RESULTS
  HAGGs did not modulate the phenotypic polarization and the cytokine production of macrophages. However, HAGGs significantly altered the TLR-induced cytokine production of all polarized macrophage subsets, with the exception of MΦ(IL-4). In particular, HAGGs consistently enhanced the TLR-induced IL-10 production in both classically and alternatively polarized macrophages (M1 and M2). The effect of HAGGs on TNF and IL-6 production was less pronounced and depended on the polarization status, while IL-23p19 and IL-12p35 expression was not affected. In contrast with HAGGs, immobilized IgG induced a strong upregulation of not only IL-10, but also TNF and IL-6.
  
  
  CONCLUSIONS
  HAGGs alone do not alter the phenotype and cytokine production of in vitro polarized human macrophages. In combination with TLR-ligands, however, HAGGs but not immobilized IgG shift the cytokine production of distinct macrophage subsets toward IL-10.
authors.affiliation: Department of Clinical Immunology and Rheumatology, Academic Medical Center/University of Amsterdam, Amsterdam, The Netherlands. c.a.ambarus@amc.nl
authors.forename: Carmen A
authors.initials: CA
authors.lastname: Ambarus
authors.forename: Kim C M
authors.initials: KC
authors.lastname: Santegoets
authors.forename: Lenny
authors.initials: L
authors.lastname: van Bon
authors.forename: Mark H
authors.initials: MH
authors.lastname: Wenink
authors.forename: Paul P
authors.initials: PP
authors.lastname: Tak
authors.forename: Timothy R D J
authors.initials: TR
authors.lastname: Radstake
authors.forename: Dominique L P
authors.initials: DL
authors.lastname: Baeten
mesh_terms: D000936:Antigen-Antibody Complex / Q000494:pharmacology; D002478:Cells, Cultured; D016207:Cytokines / Q000235:genetics / Q000378:metabolism*; D006801:Humans; D055767:Immobilized Proteins / Q000737:chemistry / Q000494:pharmacology; D007074:Immunoglobulin G / Q000737:chemistry / Q000494:pharmacology; D016753:Interleukin-10 / Q000235:genetics / Q000378:metabolism*; D053759:Interleukin-23 / Q000378:metabolism; D008024:Ligands; D008070:Lipopolysaccharides / Q000633:toxicity; D008264:Macrophages / Q000187:drug effects / Q000276:immunology / Q000378:metabolism*; D010641:Phenotype; D013696:Temperature; D051193:Toll-Like Receptors / Q000737:chemistry / Q000378:metabolism*; D015854:Up-Regulation; D005719:gamma-Globulins / Q000494:pharmacology
chemical_list: D000936:Antigen-Antibody Complex; D016207:Cytokines; D055767:Immobilized Proteins; D007074:Immunoglobulin G; D053759:Interleukin-23; D008024:Ligands; D008070:Lipopolysaccharides; D051193:Toll-Like Receptors; D005719:gamma-Globulins; D016753:Interleukin-10