Beneficial Effects of Berberine on Oxidized LDL-Induced Cytotoxicity to Human Retinal Müller Cells

Abstract

PurposeLimited mechanistic understanding of diabetic retinopathy (DR) has hindered therapeutic advances. Berberine, an isoquinolone alkaloid, has shown favorable effects on glucose and lipid metabolism in animal and human studies, but effects on DR are unknown. We previously demonstrated intraretinal extravasation and modification of LDL in human diabetes, and toxicity of modified LDL to human retinal Müller cells. We now explore pathogenic effects of modified LDL on Müller cells, and the efficacy of berberine in mitigating this cytotoxicity.MethodsConfluent human Müller cells were exposed to in vitro–modified ‘highly oxidized, glycated (HOG-) LDL versus native-LDL (N-LDL; 200 mg protein/L) for 6 or 24 hours, with/without pretreatment with berberine (5 μM, 1 hour) and/or the adenosine monophosphate (AMP)-activated protein kinase (AMPK) inhibitor, Compound C (5 μM, 1 hour). Using techniques including Western blots, reactive oxygen species (ROS) detection assay, and quantitative real-time PCR, the following outcomes were assessed: cell viability (CCK-8 assay), autophagy (LC3, Beclin-1, ATG-5), apoptosis (cleaved caspase 3, cleaved poly-ADP ribose polymerase), oxidative stress (ROS, nuclear factor erythroid 2-related factor 2, glutathione peroxidase 1, NADPH oxidase 4), angiogenesis (VEGF, pigment epithelium-derived factor), inflammation (inducible nitric oxide synthase, intercellular adhesion molecule 1, IL-6, IL-8, TNF-α), and glial cell activation (glial fibrillary acidic protein).ResultsNative-LDL had no effect on cultured human Müller cells, but HOG-LDL exhibited marked toxicity, significantly decreasing viability and inducing autophagy, apoptosis, oxidative stress, expression of angiogenic factors, inflammation, and glial cell activation. Berberine attenuated all the effects of HOG-LDL (all P < 0.05), and its effects were mitigated by AMPK inhibition (P < 0.05).ConclusionsBerberine inhibits modified LDL-induced Müller cell injury by activating the AMPK pathway, and merits further study as an agent for preventing and/or treating DR.

Berberine for prevention of dementia associated with diabetes and its comorbidities: A systematic review

“…Evidence suggests that the status of retinal neuronal structure and vasculature can reflect that of the cerebral nervous system [211]. Our literature survey revealed that berberine could prevent diabetic retinopathy [64][65][66]. Although the mechanistic link between retinal injuries and cognitive dysfunction is not clear, these data support that berberine could prevent diabetes-associated damages to the neuronal network in the central nervous system, including retina.…”

“…As shown in Table 8, berberine protected retinal Müller cells from HG-and LDL-induced damage via enhancing AMPK signaling [65,66] and prevented retinal endothelial injuries induced by HGactivated leukocytes [64].…”

“…AMPK is a serine/threonine kinase that is activated in response to adenosine triphosphate (ATP) depletion; its action is to restore cellular ATP levels and energy supply, acting as an energy sensor and a metabolic master regulator [213]. Enhanced AMPK activity, upon berberine-treatment, has been observed in several studies using diabetic animal models [63,65,102,128] as well as in vitro models [57,65,66,114,128,132,135]. However, it is not clear whether the glucose-lowering effect is indeed mediated by AMPK activation [57].…”

IL-10 inhibits retinal pigment epithelium cell proliferation and migration through regulation of VEGF in rhegmatogenous retinal detachment

“…RPE cells migrate to the vitreous body, promote secretion of a large amount of inflammatory cytokines and facilitate the secretion of ECM, ultimately leading to ECM reconstruction and the development of retinal detachment (24,25). RRD is an inflammatory pathological process, in which a tear forms on the lower surface of retina or at the interface between the vitreous body and the retina, and leads to further secretion of inflammatory cytokines, including IL-1β and IL-6.…”

A journey into the retina: Müller glia commanding survival and death

“…This factor can be primarily secreted by MGCs after prolonged exposure to high levels of glucose and fatty acids (oleic and linoleic acid), two harmful stimuli frequently observed in the metabolic syndrome (Capozzi et al., ). In this inflammatory environment, ROS levels are increased and they oxidize low‐density lipoprotein molecules, which have been shown to increase VEGF synthesis (Fu et al., ).…”