Elevated A20 contributes to age-dependent macrophage dysfunction in the lungs

Cecilia A. Hinojosa, Ramya Akula Suresh Babu, Md M. Rahman, Gabriel Fernandes, Angela R. Boyd, Carlos J. Orihuela

Research output: Contribution to journalArticle

25 Scopus citations

Abstract

Advanced age is associated with chronic low-grade inflammation (i.e. inflamm-aging) and poor macrophage function that includes a weak pro-inflammatory cytokine response to bacteria and diminished phagocytosis (i.e. age-dependent macrophage dysfunction [ADMD]). One reason for this is that ADMD is associated with poor NFκB and MAPK activation following Toll-like receptor stimulation. Herein, we tested the hypothesis that inflamm-aging induces production of A20, a cytosolic and homeostatic suppressor of the NFκB and MAPK signaling cascades that deubiquitinates (i.e. inactivates) the common upstream signaling molecule TRAF6, and this is responsible for ADMD. Western blots and immunohistochemistry comparing tissues from young, mature, and aged C57BL/6 mice indicated that A20 was strongly elevated in the lungs of aged mice but not in other tissues. Elevated A20 was also detected in alveolar macrophages (AM) from aged mice. In contrast CYLD, a second deubiquitinase that also negatively regulates the NFκB pathway was decreased with aging. Following co-incubation of AM with the bacteria Streptococcus pneumoniae, TRAF6 polyubiquitination was diminished in AM isolated from aged versus young mice. A20 production was inducible in the J774A.1 macrophage cell line and C57BL/6. AM by overnight incubation with TNFα but not IL-6. Retrovirus-induced expression of A20 in J774A.1 cells resulted in their diminished production of IL-6 following exposure to S. pneumoniae but had no effect on levels of phagocytosis. Overnight incubation of AM from young mice with TNFα also resulted in a dampened IL-6 response to S. pneumoniae. Finally, dietary supplementation of aged mice with anti-inflammatory n-3 polyunsaturated fatty acids in the form of fish oil lowered lung A20 levels and enhanced resistance, including a 100-fold reduction in bacterial titers in the lungs, to experimental challenge with S. pneumoniae. We conclude that elevated A20 due to TNFα partially explains the ADMD phenotype and that ADMD is potentially reversible.

Original languageEnglish (US)
Pages (from-to)58-66
Number of pages9
JournalExperimental Gerontology
Volume54
DOIs
StatePublished - Jun 2014

Keywords

  • Aging
  • Infection
  • Inflammation
  • Innate immunity
  • Macrophage
  • Pneumonia

ASJC Scopus subject areas

  • Biochemistry
  • Aging
  • Molecular Biology
  • Genetics
  • Endocrinology
  • Cell Biology

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  • Cite this

    Hinojosa, C. A., Akula Suresh Babu, R., Rahman, M. M., Fernandes, G., Boyd, A. R., & Orihuela, C. J. (2014). Elevated A20 contributes to age-dependent macrophage dysfunction in the lungs. Experimental Gerontology, 54, 58-66. https://doi.org/10.1016/j.exger.2014.01.007