Green Tea Polyphenol-Sensitive Calcium Signaling in Immune T Cell Function

Abstract

Polyphenol compounds found in green tea have a great therapeutic potential to influence multiple human diseases including malignancy and inflammation. In this mini review, we describe effects of green tea and the most important component EGCG in malignancy and inflammation. We focus on cellular mechanisms involved in the modification of T cell function by green tea polyphenol EGCG. The case is made that EGCG downregulates calcium channel activity by influencing miRNAs regulating expression of the channel at the post-transcriptional level.

Keywords: Ca2+ influx; EGCG; SOCE; T cells; miR-15b.

Figure 1

Gut microbiota in modulation of green tea into different metabolites and possible immune T cells dysregulation. EGCG and EGCG derived metabolites produced by gut microbiota could be modifying the effector functions of immune T cells by different mechanisms such as upregulating the miRNAs, cytokine production, or Ca²⁺ activity.

Figure 2

Effect of EGCG on miRNA and Ca²⁺ signaling in T cells. EGCG is able to upregulate miR-15b-5p, thus decreasing Calcium influx (SOCE) proteins Orai1/STIM2. As a result, Ca²⁺-sensitive functions of T cells such as cell proliferation and cell growth in mice CD4⁺ T cells are blunted. As shown in human Jurkat lymphoblasts, EGCG also downregulates the PTEN/mTOR pathway and mitochondrial potential in addition to the Calcium influx, thus affecting the cell growth and proliferation.