title: TLR ligands and cytokines induce CXCR3 ligands in endothelial cells: enhanced CXCL9 in autoimmune arthritis.
abstract: CXC chemokines are potent attractants of neutrophil granulocytes, T cells or natural killer cells. Toll-like receptors (TLR) recognize microbial components and are also activated by endogenous molecules possibly implicated in autoimmune arthritis. In contrast to CXC chemokine ligand 8 (CXCL8), no CXC chemokine receptor 3 (CXCR3) ligand (ie CXCL9, CXCL10 and CXCL11) was induced by bacterial TLR ligands in human microvascular endothelial cells (HMVEC). However, peptidoglycan (PGN), double-stranded (ds) RNA or lipopolysaccharide (LPS) (TLR2, TLR3 or TLR4 ligands, respectively) synergized with interferon-gamma (IFN-gamma) at inducing CXCL9 and CXCL10. In contrast, enhanced CXCL11 secretion was only obtained when IFN-gamma was combined with TLR3 ligand. Furthermore, flagellin, loxoribine and unmethylated CpG oligonucleotide (TLR5, TLR7 and TLR9 ligands, respectively) did not enhance IFN-gamma-dependent CXCR3 ligand production in HMVEC. In analogy with TLR ligands, tumor necrosis factor-alpha (TNF-alpha) or interleukin-1beta (IL-1beta), in combination with IFN-gamma, synergistically induced CXCL9 and CXCL11 in HMVEC and human fibroblasts, two fundamental cell types delineating the joint cavity. Etanercept, a humanized soluble recombinant p75 TNF-receptor/IgG(1)Fc fusionprotein, neutralized synergistic CXCL9 production induced by TNF-alpha plus IFN-gamma, but not synergy between IFN-gamma and the TLR ligands PGN or LPS. Synovial chemokine concentrations exemplify the physiopathological relevance of the observed in vitro chemokine production patterns. In synovial fluids of patients with spondylarthropathies (ie ankylosing spondylitis or psoriatic arthritis) or rheumatoid arthritis, significantly enhanced CXCL9, but not CXCL11 levels, were detected compared to concentrations in synovial fluids of patients with metabolic crystal-induced arthritis. Thus, CXCL9 is an important chemokine in autoimmune arthritis.
authors.affiliation: Laboratory of Molecular Immunology, Rega Institute for Medical Research, University of Leuven, Leuven, Belgium.
authors.forename: Tamara
authors.initials: T
authors.lastname: Loos
authors.forename: Lies
authors.initials: L
authors.lastname: Dekeyzer
authors.forename: Sofie
authors.initials: S
authors.lastname: Struyf
authors.forename: Evemie
authors.initials: E
authors.lastname: Schutyser
authors.forename: Klara
authors.initials: K
authors.lastname: Gijsbers
authors.forename: Mieke
authors.initials: M
authors.lastname: Gouwy
authors.forename: Annelies
authors.initials: A
authors.lastname: Fraeyman
authors.forename: Willy
authors.initials: W
authors.lastname: Put
authors.forename: Isabelle
authors.initials: I
authors.lastname: Ronsse
authors.forename: Bernard
authors.initials: B
authors.lastname: Grillet
authors.forename: Ghislain
authors.initials: G
authors.lastname: Opdenakker
authors.forename: Jo
authors.initials: J
authors.lastname: Van Damme
authors.forename: Paul
authors.initials: P
authors.lastname: Proost
mesh_terms: D000293:Adolescent; D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D000942:Antigens, Bacterial; D000956:Antigens, Viral; D015535:Arthritis, Psoriatic / Q000378:metabolism*; D001172:Arthritis, Rheumatoid / Q000378:metabolism*; D002478:Cells, Cultured; D019743:Chemokines, CXC / Q000276:immunology / Q000378:metabolism*; D018899:CpG Islands; D042783:Endothelial Cells; D005260:Female; D005347:Fibroblasts / Q000378:metabolism; D006801:Humans; D007371:Interferon-gamma; D007375:Interleukin-1; D008024:Ligands; D008297:Male; D008875:Middle Aged; D009841:Oligonucleotides; D054367:Receptors, CXCR3; D019707:Receptors, Chemokine / Q000378:metabolism*; D013582:Synovial Fluid / Q000378:metabolism; D051193:Toll-Like Receptors / Q000378:metabolism*; D014409:Tumor Necrosis Factor-alpha
chemical_list: D000942:Antigens, Bacterial; D000956:Antigens, Viral; C515187:CXCR3 protein, human; D019743:Chemokines, CXC; D007375:Interleukin-1; D008024:Ligands; D009841:Oligonucleotides; D054367:Receptors, CXCR3; D019707:Receptors, Chemokine; D051193:Toll-Like Receptors; D014409:Tumor Necrosis Factor-alpha; D007371:Interferon-gamma