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Age-dependent decrease in Toll-like receptor 4-mediated proinflammatory cytokine production and mitogen-activated

Eric D Boehmer1, Joanna Goral, Douglas E Faunce

  • 1Neurobiology and Anatomy, Loyola University Medical Center, 2160 South First Avenue, Bldg. 110, Rm. 4220, Maywood, IL 60153, USA.

Journal of Leukocyte Biology
|November 25, 2003
PubMed

Insights

Aging impairs macrophage function, reducing proinflammatory cytokine production. This is linked to lower levels and activation of mitogen-activated protein kinases (MAPKs), suggesting a mechanism for age-related immune decline.

Area of Science:

  • Immunology
  • Gerontology
  • Cellular Biology

Background:

  • Elderly individuals exhibit increased susceptibility to infections due to age-related immune changes.
  • Macrophages, key immune cells, are known to be functionally impaired in aged individuals.
  • Proinflammatory cytokine production (TNF-alpha, IL-6) by macrophages is crucial for immune response but can be dysregulated with age.

Purpose of the Study:

  • To investigate age-associated alterations in TNF-alpha and IL-6 production in mouse macrophages.
  • To examine changes in mitogen-activated protein kinase (MAPK) expression and activation in aged macrophages.
  • To determine the correlation between MAPK alterations and cytokine production in aging immune cells.

Main Methods:

  • Thioglycollate-elicited peritoneal macrophages were isolated from young and aged mice.
  • Macrophages were stimulated with lipopolysaccharide (LPS) to assess cytokine production (TNF-alpha, IL-6).
  • Levels of total and activated MAPKs (p38, JNK) and surface Toll-like receptor-4 (TLR4) were measured.

Main Results:

  • LPS-stimulated macrophages from aged mice showed significantly reduced production of TNF-alpha and IL-6 compared to young mice.
  • Aged macrophages exhibited diminished levels of total p38 and JNK MAPKs (>25% reduction).
  • Activation of p38 and JNK MAPKs in response to LPS was also reduced in aged macrophages (<70% of young controls).

Conclusions:

  • Macrophages from aged mice display suppressed proinflammatory cytokine production.
  • Decreased total levels and LPS-stimulated activation of p38 and JNK MAPKs correlate with reduced cytokine production.
  • Reduced MAPK expression may represent a key mechanism underlying age-related immune system deterioration.

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