Oxidative stress is involved in the heat stress-induced downregulation of TCR zeta chain expression and TCR/CD3-mediated [Ca(2+)](i) response in human T-lymphocytes.
Exposure of human T-lymphocytes to heat downregulates TCR zeta chain expression and inhibits (TCR)/CD3-mediated production of inositol triphosphate and [Ca(2+)](i) signaling. Here we investigated whether oxidative stress is involved in the heat-induced downregulation of TCR/CD3-mediated signaling. To this end, we have studied the effect of a thiol antioxidant, N-acetyl-L-cysteine (NAC), and a non-thiol antioxidant, allopurinol, on heat-induced downregulation of TCR/CD3-mediated signaling. We found that preincubation of cells with 10mM NAC significantly reversed the downregulation of TCR/CD3-mediated [Ca(2+)](i) response and restored the suppression of TCR zeta chain protein expression as well as prevented its increased membrane distribution in heat-treated cells. NAC also reversed the downregulation of TCR zeta chain mRNA expression and the active 94kDa TCR zeta chain transcription factor, Elf-1, in heat-treated cells. Consistent with the increase in the TCR zeta chain, preincubation with NAC increased the levels of antigen receptor-induced tyrosine phosphorylation of several cytosolic proteins. Finally, treatment with NAC was able to reverse the suppression of IL-2 production in heat-treated cells. Inactive analog, N-acetylserine, failed to reverse the heat-induced downregulation of TCR/CD3-mediated signaling. Allopurinol, another potent non-thiol antioxidant, also restored the TCR/CD3-mediated [Ca(2+)](i) response in heat-treated cells. These results demonstrate that antioxidants restore the expression of TCR zeta chain and reverse the TCR/CD3-mediated signaling abnormalities associated with heat stress and suggest that heat shock-induced oxidative stress is a mediator of the heat-induced biochemical damage that leads to downregulation of signaling in human T-lymphocytes.
Nambiar
Madhusoodana P
MP
Department of Cellular Injury, Walter Reed Army Institute of Research, Silver Spring, MD 20910-7500, USA.
Fisher
Carolyn U
CU
Enyedy
Edith J
EJ
Warke
Vishal G
VG
Kumar
Anil
A
Tsokos
George C
GC
D000111:Acetylcysteine / Q000494:pharmacology; D000493:Allopurinol / Q000494:pharmacology; D002118:Calcium / Q000378:metabolism; D020013:Calcium Signaling / Q000502:physiology*; D002458:Cell Fractionation; D004268:DNA-Binding Proteins / Q000235:genetics / Q000378:metabolism; D015536:Down-Regulation; D005434:Flow Cytometry; D016166:Free Radical Scavengers / Q000494:pharmacology; D006358:Hot Temperature; D006801:Humans; D007166:Immunosuppressive Agents / Q000494:pharmacology; D007376:Interleukin-2 / Q000378:metabolism; D008213:Lymphocyte Activation; D008565:Membrane Proteins / Q000235:genetics / Q000378:metabolism*; D016853:Muromonab-CD3 / Q000494:pharmacology; D018384:Oxidative Stress; D017382:Reactive Oxygen Species / Q000378:metabolism; D017260:Receptor-CD3 Complex, Antigen, T-Cell / Q000378:metabolism*; D011948:Receptors, Antigen, T-Cell / Q000235:genetics / Q000378:metabolism*; D013601:T-Lymphocytes / Q000187:drug effects / Q000276:immunology / Q000378:metabolism*; D014157:Transcription Factors / Q000235:genetics / Q000378:metabolism
D004268:DNA-Binding Proteins; D016166:Free Radical Scavengers; D007166:Immunosuppressive Agents; D007376:Interleukin-2; D008565:Membrane Proteins; D016853:Muromonab-CD3; D017382:Reactive Oxygen Species; D017260:Receptor-CD3 Complex, Antigen, T-Cell; D011948:Receptors, Antigen, T-Cell; D014157:Transcription Factors; C054979:antigen T cell receptor, zeta chain; D000493:Allopurinol; D002118:Calcium; D000111:Acetylcysteine