Epigallocatechin-3-gallate (EGCG) attenuates inflammation in MRL/lpr mouse mesangial cells.
Epigallocatechin-3-gallate (EGCG), a bioactive component of green tea, has been reported to exert anti-inflammatory effects on immune cells. EGCG is also shown to activate the metabolic regulator, adenosine 5'-monophosphate-activated protein kinase (AMPK). Reports have also indicated that EGCG inhibits the immune-stimulated phosphoinositide 3-kinase (PI3K)/Akt/mammalian target of rapamycin (mTOR) pathway. The PI3K/Akt/mTOR pathway has been implicated in mesangial cell activation in lupus. Mesangial cells from MRL/lpr lupus-like mice are hyper-responsive to immune stimulation and overproduce nitric oxide (NO) and other inflammatory mediators when stimulated. In our current studies, we sought to determine the mechanism by which EGCG attenuates immune-induced expression of pro-inflammatory mediators. Cultured mesangial cells from MRL/lpr mice were pre-treated with various concentrations of EGCG and stimulated with lipopolysaccharide (LPS)/interferon (IFN)-gamma. EGCG activated AMPK and blocked LPS/IFN-gamma-induced inflammatory mediator production (iNOS expression, supernatant NO and interleukin-6). Interestingly, EGCG attenuated inflammation during AMPK inhibition indicating that the anti-inflammatory effect of EGCG may be partially independent of AMPK activation. Furthermore, we found that EGCG effectively inhibited the immune-stimulated PI3K/Akt/mTOR pathway independently of AMPK, by decreasing phosphorylation of Akt, suggesting an alternate mechanism for EGCG-mediated anti-inflammatory action in mesangial cells. Taken together, these studies show that EGCG attenuated inflammation in MRL/lpr mouse mesangial cells via the PI3K/Akt/mTOR pathway. Our findings suggest a potential therapeutic role for the use of EGCG to regulate inflammation and control autoimmune disease.
Virginia College of Osteopathic Medicine, Blacksburg, VA 24060, USA. apeairs@vcom.vt.edu
Abigail
A
Peairs
Rujuan
R
Dai
Lu
L
Gan
Samuel
S
Shimp
M Nichole
MN
Rylander
Liwu
L
Li
Christopher M
CM
Reilly
D055372:AMP-Activated Protein Kinases / Q000378:metabolism; D000818:Animals; D002392:Catechin / Q000031:analogs & derivatives* / Q000494:pharmacology; D002470:Cell Survival / Q000187:drug effects; D005260:Female; D007249:Inflammation / Q000276:immunology; D007371:Interferon-gamma / Q000276:immunology; D047908:Intracellular Signaling Peptides and Proteins / Q000378:metabolism; D008070:Lipopolysaccharides / Q000276:immunology; D050527:Mesangial Cells / Q000166:cytology / Q000187:drug effects* / Q000276:immunology* / Q000378:metabolism; D051379:Mice; D019463:Mice, Inbred MRL lpr; D019869:Phosphatidylinositol 3-Kinases / Q000378:metabolism; D010766:Phosphorylation; D017346:Protein Serine-Threonine Kinases / Q000378:metabolism; D051057:Proto-Oncogene Proteins c-akt / Q000378:metabolism; D015398:Signal Transduction / Q000187:drug effects; D058570:TOR Serine-Threonine Kinases
D055372:AMP-Activated Protein Kinases; D002392:Catechin; D007371:Interferon-gamma; D047908:Intracellular Signaling Peptides and Proteins; D008070:Lipopolysaccharides; D019869:Phosphatidylinositol 3-Kinases; D017346:Protein Serine-Threonine Kinases; D051057:Proto-Oncogene Proteins c-akt; D058570:TOR Serine-Threonine Kinases; C045651:epigallocatechin gallate; C546843:mTOR protein, mouse