Eupatilin inhibits T-cell activation by modulation of intracellular calcium flux and NF-kappaB and NF-AT activity.
Eupatilin, one of the pharmacologically active ingredients of Artemisia princeps, exhibits a potent anti-ulcer activity, but its effects on T-cell immunity have not been investigated. Here, we show that eupatilin has a profound inhibitory effect on IL-2 production in Jurkat T cells as well as in human peripheral blood leukocytes. Eupatilin neither influenced clustering of CD3 and LFA-1 to the immunological synapse nor inhibited conjugate formation between T cells and B cells in the presence or absence of superantigen (SEE). Eupatilin also failed to inhibit T-cell receptor (TCR) internalization, thereby, suggesting that eupatilin does not interfere with TCR-mediated signals on the membrane proximal region. In unstimulated T cells, eupatilin significantly induced apoptotic cell death, as evidenced by an increased population of annexin V(+)/PI(+) cells and cleavage of caspase-3 and PARP. To our surprise, however, once cells were activated, eupatilin had little effect on apoptosis, and instead slightly protected cells from activation-induced cell death, suggesting that apoptosis also is not a mechanism for eupatilin-induced T-cell suppression. On the contrary, eupatilin dramatically inhibited I-kappaBalpha degradation and NF-AT dephosphorylation and, consequently, inhibited NF-kappaB and NF-AT promoter activities in PMA/A23187-stimulated T cells. Interestingly, intracellular calcium flux was significantly perturbed in cells pre-treated with eupatilin, suggesting that calcium-dependent cascades might be targets for eupatilin action. Collectively, our results provide evidence for dual regulatory functions of eupatilin: (1) a pro-apoptotic effect on resting T cells and (2) an immunosuppressive effect on activated T cells, presumably through modulation of Ca(2+) flux.
Kim
Young-Dae
YD
Department of Life Science, Cell Dynamics Research Center, BioImaging Research Center, and Research Center for Biomolecular Nanotechnology, GIST, Gwangju 500-712, Republic of Korea.
Choi
Suck-Chei
SC
Oh
Tae-Young
TY
Chun
Jang-Soo
JS
Jun
Chang-Duk
CD
D017209:Apoptosis; D002118:Calcium / Q000378:metabolism*; D002478:Cells, Cultured; D005419:Flavonoids / Q000494:pharmacology*; D006801:Humans; D007376:Interleukin-2 / Q000378:metabolism; D019169:Jurkat Cells; D008213:Lymphocyte Activation / Q000187:drug effects*; D016328:NF-kappa B / Q000235:genetics / Q000378:metabolism*; D050778:NFATC Transcription Factors / Q000235:genetics / Q000378:metabolism*; D015398:Signal Transduction; D013601:T-Lymphocytes / Q000378:metabolism*
D005419:Flavonoids; D007376:Interleukin-2; D016328:NF-kappa B; D050778:NFATC Transcription Factors; C045325:eupatilin; D002118:Calcium