Role of redox imbalance in the molecular mechanisms responsible for immunosenescence.
The elderly suffer impairments to their immune system, evidenced by higher susceptibility to infections, cancer, and many diseases believed to be autoimmune in nature. A dysregulated overexpression of many proinflammatory cytokines also occurs with aging, as does the synthesis of enzymes that control expression of inflammatory lipid mediators and reactive oxygen species. An inappropriate activation of redox-controlled transcription factors, like nuclear factor-kappaB, occurs in many tissues from aged donors, and has been linked to excesses in cellular oxidative stress. Recently, the peroxisome proliferator-activated receptor-alpha (PPARalpha) has been evaluated for its effects on inflammatory and adaptive immune processes. PPARalpha provides redox-balancing influences on various lymphoid cell types and their inducible responses. We recently discovered that PPARalpha transiently suppresses the transcription of gamma-interferon (IFNgamma) by inhibiting the induction of T-bet. We now report that PPARalpha expression in CD4+ T cells is affected by the aging process. Lower PPARalpha levels are present in aged CD4+ T cells, and appear responsible for the suppressed interleukin-2 and exaggerated IFNgamma responses by these cells. Restoration of PPARalpha, T-bet, interleukin-2, and IFNgamma responses was found in T cells from aged animals supplemented with vitamin E, suggesting that interventions that focus on restoring redox balance might benefit the ailing aged immune system.
Daynes
Raymond A
RA
Department of Pathology, University of Utah School of Medicine, Salt Lake City, UT 84132-2501, USA. daynes.office@path.utah.edu
Enioutina
Elena Y
EY
Jones
Dallas C
DC
D000284:Administration, Oral; D000367:Age Factors; D000375:Aging / Q000276:immunology*; D000818:Animals; D000906:Antibodies / Q000494:pharmacology; D015153:Blotting, Western; D018106:CD28 Antigens / Q000276:immunology; D017252:CD3 Complex / Q000276:immunology; D015496:CD4-Positive T-Lymphocytes / Q000187:drug effects / Q000502:physiology*; D004797:Enzyme-Linked Immunosorbent Assay; D005260:Female; D005434:Flow Cytometry; D015870:Gene Expression; D007371:Interferon-gamma / Q000378:metabolism*; D007376:Interleukin-2 / Q000378:metabolism*; D019041:L-Selectin / Q000032:analysis / Q000378:metabolism; D051379:Mice; D008807:Mice, Inbred BALB C; D008810:Mice, Inbred C57BL; D018345:Mice, Knockout; D008822:Mice, Transgenic; D010047:Ovalbumin / Q000276:immunology; D010084:Oxidation-Reduction; D011948:Receptors, Antigen, T-Cell / Q000235:genetics / Q000276:immunology; D018160:Receptors, Cytoplasmic and Nuclear / Q000235:genetics / Q000378:metabolism*; D020825:T-Box Domain Proteins; D014157:Transcription Factors / Q000235:genetics / Q000378:metabolism*; D014810:Vitamin E / Q000494:pharmacology; D000098815:T-bet Transcription Factor
D000906:Antibodies; D018106:CD28 Antigens; D017252:CD3 Complex; D007376:Interleukin-2; D011948:Receptors, Antigen, T-Cell; D018160:Receptors, Cytoplasmic and Nuclear; D020825:T-Box Domain Proteins; D000098815:T-bet Transcription Factor; D014157:Transcription Factors; D019041:L-Selectin; D014810:Vitamin E; D007371:Interferon-gamma; D010047:Ovalbumin