Green Tea Catechins (EGCG) for Neurovascular Health in Glaucoma and Aging

This audio article is from VisualFieldTest.com.Read the full article here: https://visualfieldtest.com/en/green-tea-catechins-egcg-for-neurovascular-health-in-glaucoma-and-agingTest your visual field online: https://visualfieldtest.comExcerpt:EGCG and Neurovascular Health in Glaucoma and AgingGreen tea cultures have long prized their tea’s catechins—particularly epigallocatechin-3-gallate (EGCG)—for promoting health. Modern research suggests EGCG’s potent antioxidant, anti-inflammatory and vasodilatory effects might benefit the neurovascular system in glaucoma and aging. In glaucoma, retinal ganglion cells (RGCs) degenerate under stress, and intraocular pressure (IOP) rises due to trabecular meshwork (TM) dysfunction. We review animal and cell studies of EGCG on RGC survival, TM extracellular matrix (MMPs) and blood flow, then summarize limited human data on vision and ocular structure. We connect these to EGCG’s known effects on cardiovascular and cognitive aging, and discuss its bioavailability, caffeine content, and safety.Retinal Ganglion Cell Protection (Preclinical)Preclinical studies consistently show EGCG helps RGC survival after injury or elevated IOP. In a mouse glaucoma model (microbead-induced high IOP), oral EGCG (50 mg/kg·d) preserved RGC density: treated mice had significantly more fluorogold-labeled RGCs versus untreated controls (). In rats with acute IOP elevation, EGCG treatment markedly reduced optic nerve damage and inflammatory cytokines. For example, in one study EGCG lowered IL-6, TNF-α and other inflammatory signals, and inhibited NF-κB activation, thereby attenuating glaucoma symptoms and RGC injury (). These neuroprotective effects likely derive from EGCG’s ability to quench free radicals and block stress pathways (e.g. activating Nrf2/HO-1 in ischemia models ()). In cell culture, EGCG blocked oxidative and ultraviolet stress in RGC lines. Thus, multiple lines of evidence indicate that EGCG can mitigate RGC degeneration in animal glaucoma or optic nerve injury models (often via anti-oxidant and anti-inflammatory mechanisms) () (). Trabecular Meshwork and Aqueous OutflowMMPs (matrix metalloproteinases) regulate the extracellular matrix of the TM and thus aqueous outflow and IOP. Adequate MMP activity “elevates aqueous outflow, reducing IOP,” whereas reduced MMPs increase outflow resistance (). EGCG and other catechins are known MMP modulators. For instance, catechin treatment can suppress MMP-9 expression in humans (e.g. lowering MMP-9 in hypertension) (). In ocular models, EGCG has anti-fibrotic and cell-protective effects on TM cells. Zhou et al. found 40 μM EGCG dramatically improved human and porcine TM cell survival under ER stress: EGCG curtailed stress markers (ATF4, HSPA5, DDIT3) by ~50-70% and rescued cell viability () (). By reducing TM cell dysfunction, EGCG pretreatment may help maintain normal outflow. Similarly, EGCG strongly inhibited TGF-β1–induced fibrotic changes in human Tenon’s fibroblasts: treated cells showed dramatically lower α-smooth muscle actin and collagen expression (). This suggests EGCG can blunt ECM deposition, which in TM would preserve lumen. In sum, preclinical data imply EGCG’s anti-oxidant/anti-fibrotic actions protect TM cells and could facilitate aqueous clearance, complementing its IOP-lowering potential () ().Ocular Perfusion and Vascular EffectsEGCG has vasoactive properties that may boost ocular perfusion. Mechanistically, EGCG activates endothelial nitric oxide synthase (eNOS) and increases nitric oxide (NO) production via PI3K/Akt pathways (). This causes vasodilation and improved microcirculation. In the retina, enhanced NO-mediated blood flow supplies oxygen and nutrients to neurons. As a review notes, EGCG “activating eSupport the show