title: Ankylosing spondylitis macrophage production of higher levels of interleukin-23 in response to lipopolysaccharide without induction of a significant unfolded protein response.
abstract: OBJECTIVE
  Previous studies of the HLA-B27-transgenic rat model of ankylosing spondylitis (AS) suggested that macrophages develop an intracellular stress response called the unfolded protein response (UPR) and, as a result, secrete increased amounts of cytokines in response to Toll-like receptor agonists such as lipopolysaccharide (LPS). Our objective was to determine whether macrophages from AS patients also undergo a UPR and secrete increased cytokines/chemokines in response to LPS.
  
  
  METHODS
  Peripheral blood monocytes isolated from 10 AS patients and 10 healthy controls were differentiated in vitro with macrophage colony-stimulating factor. Select samples were treated with interferon-γ (IFNγ) to up-regulate class I major histocompatibility complex (HLA-B) expression prior to stimulation with LPS for either 3 hours (for RNA) or 8-24 hours (for supernatant). UPR induction was assessed by measuring the expression of messenger RNA for ERdj4, BiP, and CCAAT/enhancer binding protein homologous protein 10 (CHOP).
  
  
  RESULTS
  Although IFNγ treatment up-regulated HLA-B expression (2-fold; P < 0.0001), neither IFNγ nor LPS substantially enhanced BiP or CHOP expression (<1.3-fold). ERdj4 expression increased weakly, but not significantly, in AS samples treated with IFNγ plus LPS (2.2-fold; P = 0.31). In response to LPS, AS macrophages secreted more CXCL9, interleukin-10 (IL-10), IL-12p70, IL-23, and tumor necrosis factor α than did control macrophages (P ≤ 0.025). The most striking difference was observed for IL-23 (median 265 pg/ml in AS patients versus 9 pg/ml in controls; P = 0.0007). We did not detect significant differences in IL-6, IL-8, or IFNβ production.
  
  
  CONCLUSIONS
  The greater production of IL-23 by AS patient macrophages in response to LPS provides further support for the development of Th17/IL-23-directed therapy. Since significant UPR induction was not detected in AS patient macrophages, the relationship between UPR and inflammatory cytokine production remains unclear.
authors: University of Wisconsin Madison, School of Medicine and Public Health, Madison, WI 53792-4108, USA.
authors: Ling
authors: L
authors: Zeng
authors: Mary J
authors: MJ
authors: Lindstrom
authors: Judith A
authors: JA
authors: Smith
mesh_terms: D000293:Adolescent; D000328:Adult; D022762:CCAAT-Enhancer-Binding Proteins / Q000378:metabolism; D016022:Case-Control Studies; D002478:Cells, Cultured; D018925:Chemokines / Q000378:metabolism; D016207:Cytokines / Q000378:metabolism; D005260:Female; D015235:HLA-B Antigens / Q000378:metabolism; D006801:Humans; D007371:Interferon-gamma / Q000494:pharmacology; D053759:Interleukin-23 / Q000378:metabolism*; D008070:Lipopolysaccharides / Q000494:pharmacology*; D008264:Macrophages / Q000187:drug effects* / Q000378:metabolism* / Q000473:pathology; D008297:Male; D008875:Middle Aged; D009842:Oligopeptides / Q000378:metabolism; D013167:Spondylitis, Ankylosing / Q000378:metabolism* / Q000473:pathology; D051742:Transcription Factor CHOP / Q000378:metabolism; D056811:Unfolded Protein Response / Q000187:drug effects* / Q000502:physiology; D055815:Young Adult
chemical_list: C539791:Bax-inhibiting peptide, BIP; D022762:CCAAT-Enhancer-Binding Proteins; D018925:Chemokines; D016207:Cytokines; C497249:DDIT3 protein, human; D015235:HLA-B Antigens; D053759:Interleukin-23; D008070:Lipopolysaccharides; D009842:Oligopeptides; D051742:Transcription Factor CHOP; D007371:Interferon-gamma