Molecular Mechanisms of the Anti-Inflammatory Effects of Epigallocatechin 3-Gallate (EGCG) in LPS-Activated BV-2 Microglia Cells

Abstract

Chronic neuroinflammation is associated with many neurodegenerative diseases, such as Alzheimer’s. Microglia are the brain’s primary immune cells, and when activated, they release various proinflammatory cytokines. Several natural compounds with anti-inflammatory and antioxidant properties, such as epigallocatechin 3-gallate (EGCG), may provide a promising strategy for inflammation-related neurodegenerative diseases involving activated microglia cells. The objective of the current study was to examine the molecular targets underlying the anti-inflammatory effects of EGCG in activated microglia cells. BV-2 microglia cells were grown, stimulated, and treated with EGCG. Cytotoxicity and nitric oxide (NO) production were evaluated. Immunoassay, PCR array, and WES™ Technology were utilized to evaluate inflammatory, neuroprotective modulators as well as signaling pathways involved in the mechanistic action of neuroinflammation. Our findings showed that EGCG significantly inhibited proinflammatory mediator NO production in LPS-stimulated BV-2 microglia cells. In addition, ELISA analysis revealed that EGCG significantly decreases the release of proinflammatory cytokine IL-6 while it increases the release of TNF-α. PCR array analysis showed that EGCG downregulated MIF, CCL-2, and CSF2. It also upregulated IL-3, IL-11, and TNFS10. Furthermore, the analysis of inflammatory signaling pathways showed that EGCG significantly downregulated mRNA expression of mTOR, NF-κB2, STAT1, Akt3, CCL5, and SMAD3 while significantly upregulating the expression of mRNA of Ins2, Pld2, A20/TNFAIP3, and GAB1. Additionally, EGCG reduced the relative protein expression of NF-κB2, mTOR, and Akt3. These findings suggest that EGCG may be used for its anti-inflammatory effects to prevent neurodegenerative diseases.

Development of dietary small molecules as multi-targeting treatment strategies for Alzheimer's disease

“…A similar study reported that EGCG administration significantly inhibited IL-6, IL-8, VEGF, and PGE2 production, decreased COX-2 expression, and inhibited NF-κB activation, with subsequent inhibition of phosphorylation of p38, JNK, and ERK in IL-1β+Aβ (25-35) -induced U373MG cells [ 219 ]. Furthermore, in microglial BV-2 cells stimulated with LPS, pretreatment with EGCG significantly inhibited the production of the proinflammatory mediator NO, decreased the release of proinflammatory cytokine IL-6 while increasing TNF-α, downregulated MIF, CCL-2, and CSF2 and upregulated IL-3, IL-11, and TNFS10, significantly downregulated mTOR, NF-κB2, STAT1, Akt3, CCL5, and SMAD3 while significantly upregulating the expression of mRNA of Ins2, Pld2, A20/TNFAIP3, and GAB1 [ 220 ]. Similarly, EGCG is associated with protection against Aβ and LPS-induced neurotoxicity in SH-SY5Y and BV-2 microglial cells through the inhibition of proinflammatory cytokines (IL-1β and IL-18), the reduction in Iba-1 over-expression, and the suppression of the co-localization of caspase-1 and Iba-1 activation as shown by immunofluorescence staining.…”

Evidence-Based Approach for Secondary Prevention of Uterine Fibroids (The ESCAPE Approach)

“…EGCG possesses immunomodulatory properties, which can help regulate and balance the immune system's response. EGCG has been shown to inhibit the production of pro-inflammatory molecules, such as cytokines and chemokines, while promoting the production of anti-inflammatory substances [162]. Additionally, EGCG has been found to modulate immune cell function by enhancing the activity of natural killer (NK) cells, T cells, and B cells [163].…”

Structural Modification of Epigallocatechin-3-gallate to (2R,3R)-5,7-dimethoxy-2-(3,4,5-trimethoxyphenyl)chroman-3-yl l-valinate in Four Steps

“…Unlike green tea, black tea involves a fermentation process in its preparation, during which these phenolic compounds are oxidized to form new compounds, such as theobromine and theaflavin, thereby diminishing the EGCG content in black tea. EGCG exhibits a broad spectrum of biological activities, including hypoglycemic [1], antibacterial [2], antiviral [3], antioxidant [4], anti-atherosclerotic [5], antitumor [6] and anti-inflammatory [7] effects. Therefore, tea and its extract have been widely commercialized, commonly in the pharmaceutical, healthcare, and food industries [8][9][10].…”