The Natural Polyphenol Epigallocatechin Gallate Protects Intervertebral Disc Cells from Oxidative Stress

Abstract

Oxidative stress-related phenotypic changes and a decline in the number of viable cells are crucial contributors to intervertebral disc degeneration. The polyphenol epigallocatechin 3-gallate (EGCG) can interfere with painful disc degeneration by reducing inflammation, catabolism, and pain. In this study, we hypothesized that EGCG furthermore protects against senescence and/or cell death, induced by oxidative stress. Sublethal and lethal oxidative stress were induced in primary human intervertebral disc cells with H2O2 (total n = 36). Under sublethal conditions, the effects of EGCG on p53-p21 activation, proliferative capacity, and accumulation of senescence-associated β-galactosidase were tested. Further, the effects of EGCG on mitochondria depolarization and cell viability were analyzed in lethal oxidative stress. The inhibitor LY249002 was applied to investigate the PI3K/Akt pathway. EGCG inhibited accumulation of senescence-associated β-galactosidase but did not affect the loss of proliferative capacity, suggesting that EGCG did not fully neutralize exogenous radicals. Furthermore, EGCG increased the survival of IVD cells in lethal oxidative stress via activation of prosurvival PI3K/Akt and protection of mitochondria. We demonstrated that EGCG not only inhibits inflammation but also can enhance the survival of disc cells in oxidative stress, which makes it a suitable candidate for the development of novel therapies targeting disc degeneration.

An Inflammatory Nucleus Pulposus Tissue Culture Model to Test Molecular Regenerative Therapies: Validation with Epigallocatechin 3-Gallate

“…EGCG inhibited the expression of inflammatory markers (IL-6, IL-8, PTGS2, TLR2, and iNOS), collagenases (MMP1, MMP3, and MMP13) and NGF in human IVD cells cultured adherently and in alginate beads [11]. EGCG also protected IVD cells from oxidative stress caused by exogenous radicals [37] and, moreover, locally delivered EGCG reduced radicular pain in a rat model of NP herniation [11]. Therefore, we selected this compound for validation of the new inflammation-induced NP culture model.…”

“…Compounds derived from traditional medicinal plants act on several signal transduction and apoptotic cascades at the same time, while having minimal side effects [33]. We have shown before that natural compounds such as resveratrol [34], curcumin [35], triptolide [36] and epigallocatechin 3-gallate (EGCG) [11,37] exhibit anti-inflammatory, anti-catabolic and anti-oxidant activity in disc cells. Although more research is needed to fully understand the effects of these compounds on the integrity of the IVD, it has been suggested that they can delay degeneration of the NP or even reverse it.…”

ROS: Crucial Intermediators in the Pathogenesis of Intervertebral Disc Degeneration

“…H 2 O 2 resulted in a rapid increase in ROS production and DNA damage in human NP cells. Consequently, the ATM-Chk2-p53-p21-Rb pathway and the p16-Rb pathway were activated to induce premature senescence of human NP cells [15, 34]. H 2 O 2 also induced premature senescence of human CEP cells through the p53-p21-Rb pathway [91].…”

“…Polyphenol epigallocatechin 3-gallate is a polyphenol redox scavenger. In vitro investigations have found that polyphenol epigallocatechin 3-gallate not only suppresses the senescence and apoptosis of human NP cells under oxidative stress, but also inhibits the expression of cytokines and MMPs in human NP cells through regulating the MAPK pathway and the NF- κ B pathway [34, 35]. …”

TRPC6 in simulated microgravity of intervertebral disc cells

“…Primary cells were isolated from human IVD biopsies from patients undergoing spinal surgery (approved by the ethical committees in Zurich and Lucerne, Switzerland, and after informed consent), as previously described [32]. For patient demographics, see Table 1.…”