Ankylosing spondylitis macrophage production of higher levels of interleukin-23 in response to lipopolysaccharide without induction of a significant unfolded protein response

Arthritis Rheum. 2011 Dec;63(12):3807-17. doi: 10.1002/art.30593.


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.

Conclusion: 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.

Publication types

  • Research Support, N.I.H., Extramural
  • Research Support, Non-U.S. Gov't

MeSH terms

  • Adolescent
  • Adult
  • CCAAT-Enhancer-Binding Proteins / metabolism
  • Case-Control Studies
  • Cells, Cultured
  • Chemokines / metabolism
  • Cytokines / metabolism
  • Female
  • HLA-B Antigens / metabolism
  • Humans
  • Interferon-gamma / pharmacology
  • Interleukin-23 / metabolism*
  • Lipopolysaccharides / pharmacology*
  • Macrophages / drug effects*
  • Macrophages / metabolism*
  • Macrophages / pathology
  • Male
  • Middle Aged
  • Oligopeptides / metabolism
  • Spondylitis, Ankylosing / metabolism*
  • Spondylitis, Ankylosing / pathology
  • Transcription Factor CHOP / metabolism
  • Unfolded Protein Response / drug effects*
  • Unfolded Protein Response / physiology
  • Young Adult


  • Bax-inhibiting peptide, BIP
  • CCAAT-Enhancer-Binding Proteins
  • Chemokines
  • Cytokines
  • DDIT3 protein, human
  • HLA-B Antigens
  • Interleukin-23
  • Lipopolysaccharides
  • Oligopeptides
  • Transcription Factor CHOP
  • Interferon-gamma