Peripheral monocyte functions and activation in patients with quiescent Crohn's disease

PLoS One. 2013 Apr 26;8(4):e62761. doi: 10.1371/journal.pone.0062761. Print 2013.

Abstract

Recent developments suggest a causal link between inflammation and impaired bacterial clearance in Crohn's disease (CD) due to alterations of intestinal macrophages. Studies suggest that excessive inflammation is the consequence of an underlying immunodeficiency rather than the primary cause of CD pathogenesis. We characterized phenotypic and functional features of peripheral blood monocytes of patients with quiescent CD (n = 18) and healthy controls (n = 19) by analyses of cell surface molecule expression, cell adherence, migration, chemotaxis, phagocytosis, oxidative burst, and cytokine expression and secretion with or without lipopolysaccharide (LPS) priming. Peripheral blood monocytes of patients with inactive CD showed normal expression of cell surface molecules (CD14, CD16, CD116), adherence to plastic surfaces, spontaneous migration, chemotaxis towards LTB4, phagocytosis of E. coli, and production of reactive oxygen species. Interestingly, peripheral blood monocytes of CD patients secreted higher levels of IL1β (p<.05). Upon LPS priming we found a decreased release of IL10 (p<.05) and higher levels of CCL2 (p<.001) and CCL5 (p<.05). The expression and release of TNFα, IFNγ, IL4, IL6, IL8, IL13, IL17, CXCL9, and CXCL10 were not altered compared to healthy controls. Based on our phenotypic and functional studies, peripheral blood monocytes from CD patients in clinical remission were not impaired compared to healthy controls. Our results highlight that defective innate immune mechanisms in CD seems to play a role in the (inflamed) intestinal mucosa rather than in peripheral blood.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Adult
  • Antigens, CD / genetics
  • Antigens, CD / immunology
  • Case-Control Studies
  • Cell Adhesion / drug effects
  • Cells, Cultured
  • Chemotaxis / drug effects
  • Crohn Disease / genetics
  • Crohn Disease / immunology*
  • Crohn Disease / pathology
  • Escherichia coli / immunology
  • Female
  • Gene Expression / drug effects*
  • Gene Expression / immunology
  • Humans
  • Interferon-gamma / genetics
  • Interferon-gamma / immunology
  • Interleukins / genetics
  • Interleukins / immunology
  • Lipopolysaccharides / pharmacology*
  • Male
  • Middle Aged
  • Monocytes / drug effects*
  • Monocytes / immunology
  • Monocytes / pathology
  • Phagocytosis / drug effects
  • Remission Induction
  • Tumor Necrosis Factor-alpha / genetics
  • Tumor Necrosis Factor-alpha / immunology

Substances

  • Antigens, CD
  • Interleukins
  • Lipopolysaccharides
  • Tumor Necrosis Factor-alpha
  • Interferon-gamma

Grants and funding

The study was supported by grants of the Broad Medical Research Program (BMRP Reference No. IBD0201, to DF and JD), the German Research Foundation (DFG Reference No. DA1161/4-1, to JD and DF), and the Innovative Medical Research Program of the University of Münster (IMF Reference No. DÄ120904, to JD and DF). The funders had no role in study design, data collection and analysis, decision to publish, or preparation of the manuscript.