Dose-dependent responses of I3C and DIM on T-cell activation in the human T lymphocyte Jurkat cell line

Authors: LIU, MAN - Jiangsu Normal University; Yasmeen, Rumana; Fukagawa, Naomi; YU, LIANGLI - University Of Maryland; KIM, YOUNG - National Cancer Institute (NCI, NIH); Wang, Thomas - Tom

Submitted to: International Journal of Molecular Sciences
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 6/28/2017
Publication Date: 7/1/2017
Citation: Liu, M., Yasmeen, R., Fukagawa, N.K., Yu, L., Kim, Y.S., Wang, T.T. 2017. Dose-dependent responses of I3C and DIM on T-cell activation in the human T lymphocyte Jurkat cell line. International Journal of Molecular Sciences. 18(7). pii: E1409. https://doi.org/10.3390/ijms18071409.
DOI: https://doi.org/10.3390/ijms18071409

Interpretive Summary: Indole-3-carbinol (I3C) and its dimer diindolylmethane (DIM) are bioactive metabolites of a glucosinolate glucobrassicin found in cruciferous vegetables. Both I3C and DIM have been reported to possess anti-apoptotic, anti-proliferative and anti-carcinogenic properties via the modulation of immune pathways. However, results from these studies remain inconclusive since they lack thorough evaluation of these bioactive’s physiological versus pharmacological effects. In the present study, we investigated I3C and DIM’s dose-dependent effects on cytokines' production in human T lymphocytes Jurkat Clone E6-1. The results showed that I3C and DIM pretreatment, at higher concentrations of 50 and 10 µM respectively, significantly increased PMA/ionomycin-induced IL-2, IL-8 and TNF-alpha a production, measured by RT-PCR and ELISA. As a plausible mechanism underlying such pronounced cytokine release, we found robust increase in downstream NF-kappa B and NFAT1 signaling with I3C pretreatment, whereas, DIM pretreatment only significantly induced NF-kappa B activation, but not NFAT1. We hypothesize that I3C/DIM pretreatment primes the T cells for rapid calcium release upon PMA/ionomycin stimulation, which in turn differentially induces two major downstream Ca2+-dependent inflammatory pathways, NF-kappa B and NFAT. Our data show novel insights into the mechanisms underlying induction of pro-inflammatory cytokine released by pharmacological concentrations of I3C and DIM, an effect negligible under physiological conditions. This study provides mechanistic information about cruciferous vegetable-derived compounds on the immune system and can benefit basic, as well as translation scientists who perform work on diet and immune responses.

Technical Abstract: Indole-3-carbinol (I3C) and its dimer diindolylmethane (DIM) are bioactive metabolites of a glucosinolate glucobrassicin found in cruciferous vegetables. Both I3C and DIM have been reported to possess anti-apoptotic, anti-proliferative and anti-carcinogenic properties via the modulation of immune pathways. However, results from these studies remain inconclusive since they lack thorough evaluation of these bioactive physiological versus pharmacological effects. In the present study, we investigated I3C and DIM’s dose-dependent effects on cytokines production in human T lymphocytes Jurkat (Clone E6-1). The results showed that I3C and DIM pretreatment, at higher concentrations of 50 and 10 µM respectively, significantly increased PMA/ionomycin-induced IL-2, IL-8 and TNF-alpha a production, measured by RT-PCR and ELISA. As a plausible mechanism underlying such pronounced cytokine release, we found robust increase in downstream NF-kappa B and NFAT1 signaling with I3C pretreatment, whereas, DIM pretreatment only significantly induced NF-kappa B activation, but not NFAT1. We hypothesize that I3C/DIM pretreatment primes the T cells for rapid calcium released upon PMA/ionomycin stimulation which in turn differentially induces two major downstream Ca2+-dependent inflammatory pathways, NF-kappa B and NFAT. Our data show novel insights into the mechanisms underlying the induction of pro-inflammatory cytokine released by pharmacological concentrations of I3C and DIM, an effect negligible under physiological conditions.