Suppression of early T-cell-receptor-triggered cellular activation by the Janus kinase 3 inhibitor WHI-P-154.
BACKGROUND
Therapeutic targeting of Janus kinase 3 (JAK3) has received particular attention, because it is associated with the common gamma signaling of cytokine receptors and thus vitally influences T-cell growth and survival. Recent evidence, however, indicates a critical role for JAK3 in signaling linked to the T-cell antigen receptor.


METHODS
In this study we investigated whether targeting JAK3 with a rationally designed inhibitor affects early T-cell activation events. T cells were stimulated by CD3 and CD28 cross-linking, and interleukin (IL)-2 production, activation marker expression, increase of free intracellular Ca2+ concentration, activation of the extracellular-related kinase, and nuclear translocation of transcription factors were evaluated.


RESULTS
We found that JAK3 inhibitor treatment dramatically impaired T-cell-receptor (TCR)-induced IL-2 production, surface activation marker expression (CD69, CD154), and homotypic T-cell aggregation. Accordingly, mRNA production of IL-2, interferon-gamma, and IL-10 was profoundly inhibited. Molecular analysis revealed that TCR-triggered phosphorylation of phospholipase C-gamma1, increase in cytoplasmic Ca2+ concentration, and activation of extracellular-related kinase were markedly reduced by the JAK3 inhibitor, resulting in substantially decreased DNA binding of nuclear factor of activated T cells and alkaline phosphatase-1 and subsequent IL-2 promoter activation. Remarkably, on TCR-independent stimulation, IL-2 production, CD69 expression, and blast formation were completely insensitive to JAK3 inhibitor treatment.


CONCLUSIONS
These data indicate that pharmacologic targeting of JAK3 uncouples early TCR-triggered signaling from essential downstream events, which may have important implications for the use of such compounds in T-cell-mediated disorders such as allograft rejection or graft-versus-host disease.
Säemann
Marcus D
MD
Institute of Immunology, Vienna, Austria.
Zeyda
Maximilian
M
Diakos
Christos
C
Szekeres
Andreas
A
Böhmig
Georg A
GA
Kelemen
Peter
P
Parolini
Ornella
O
Stockinger
Hannes
H
Prieschl
Eva E
EE
Stulnig
Thomas M
TM
Baumruker
Thomas
T
Zlabinger
Gerhard J
GJ
D000469:Alkaline Phosphatase / Q000378:metabolism; D002449:Cell Aggregation / Q000187:drug effects / Q000276:immunology; D004268:DNA-Binding Proteins / Q000378:metabolism; D004791:Enzyme Inhibitors / Q000494:pharmacology; D015870:Gene Expression / Q000187:drug effects / Q000276:immunology; D006084:Graft Rejection / Q000188:drug therapy / Q000276:immunology; D006801:Humans; D007376:Interleukin-2 / Q000235:genetics; D053616:Janus Kinase 3; D019169:Jurkat Cells; D008213:Lymphocyte Activation / Q000187:drug effects / Q000276:immunology*; D050778:NFATC Transcription Factors; D009687:Nuclear Proteins; D010766:Phosphorylation / Q000187:drug effects; D011401:Promoter Regions, Genetic / Q000187:drug effects / Q000276:immunology; D011505:Protein-Tyrosine Kinases / Q000037:antagonists & inhibitors* / Q000378:metabolism; D011799:Quinazolines / Q000494:pharmacology*; D011948:Receptors, Antigen, T-Cell / Q000276:immunology*; D015398:Signal Transduction / Q000187:drug effects / Q000276:immunology; D013601:T-Lymphocytes / Q000187:drug effects / Q000276:immunology*; D014157:Transcription Factors / Q000378:metabolism; D014158:Transcription, Genetic / Q000187:drug effects / Q000276:immunology; D014443:Tyrosine / Q000378:metabolism
D004268:DNA-Binding Proteins; D004791:Enzyme Inhibitors; D007376:Interleukin-2; D050778:NFATC Transcription Factors; D009687:Nuclear Proteins; D011799:Quinazolines; D011948:Receptors, Antigen, T-Cell; D014157:Transcription Factors; C113888:WHI P154; D014443:Tyrosine; D011505:Protein-Tyrosine Kinases; C507933:JAK3 protein, human; D053616:Janus Kinase 3; D000469:Alkaline Phosphatase