Relative corticosteroid insensitivity of peripheral blood mononuclear cells in severe asthma

Am J Respir Crit Care Med. 2006 Jul 15;174(2):134-41. doi: 10.1164/rccm.200512-1930OC. Epub 2006 Apr 13.


Rationale and objectives: Patients with severe asthma have a poor therapeutic response to corticosteroid therapy, and corticosteroid responsiveness cannot be easily measured in these patients. We hypothesized that this poor response is associated with a reduced effect of corticosteroids to inhibit cytokine release from activated peripheral blood mononuclear cells (PBMCs).

Methods: Patients with severe asthma were defined by American Thoracic Society criteria. We compared the suppression of LPS-induced cytokine release (monocyte chemotactic protein-1 [MCP-1], macrophage inflammatory protein [MIP] 1alpha, RANTES, tumor necrosis factor alpha, interleukin 1beta (IL-1beta), IL-8, IFN-gamma, IL-6, IL-10, and granulocyte-macrophage colony-stimulating factor [GM-CSF]) by dexamethasone from PBMCs of patients with severe asthma (n = 16), patients with nonsevere asthma (n = 19), and normal volunteers (n = 10).

Results: There was no difference in baseline spontaneous or stimulated release of these cytokines among groups. LPS-induced release of 10 cytokines was less suppressed by dexamethasone (10(-6) M) in patients with severe asthma compared with patients with nonsevere asthma, with statistical significance achieved for IL-1beta (p < 0.03), IL-8 (p < 0.03), and MIP-1alpha (p < 0.003), and borderline significance for IL-6 (p = 0.054). There was less difference between the two groups for dexamethasone at 10(-8) M. Nuclear histone deacetylase (HDAC) and histone acetyltransferase activities were reduced in patients with severe asthma compared with patients with nonsevere asthma (p < 0.01). HDAC activity reduction correlated directly to the degree of steroid insensitivity of GM-CSF (r = 0.57, p < 0.01) and IFN-gamma (r = 0.56, p < 0.05) release. Reduction in histone acetyltransferase activity related to corticosteroid use rather than asthma severity.

Conclusions: Patients with severe asthma have diminished corticosteroid sensitivity of PBMCs when compared with patients with nonsevere asthma, associated with a reduction in HDAC activity that parallels the impaired corticosteroid sensitivity.

Publication types

  • Research Support, N.I.H., Extramural

MeSH terms

  • Adult
  • Asthma / blood
  • Asthma / drug therapy
  • Asthma / physiopathology*
  • Cell Nucleus / enzymology
  • Cytokines / analysis
  • Dexamethasone / pharmacology
  • Drug Resistance
  • Female
  • Glucocorticoids / pharmacology*
  • Glucocorticoids / therapeutic use
  • Histone Acetyltransferases / metabolism
  • Histone Deacetylases / metabolism
  • Humans
  • Leukocytes, Mononuclear / drug effects*
  • Leukocytes, Mononuclear / enzymology
  • Lipopolysaccharides
  • Male
  • Middle Aged


  • Cytokines
  • Glucocorticoids
  • Lipopolysaccharides
  • Dexamethasone
  • Histone Acetyltransferases
  • Histone Deacetylases