The Anti-Inflammatory Effect of the β1-Adrenergic Receptor Antagonist Metoprolol on High Glucose Treated Human Microvascular Retinal Endothelial Cells

Abstract

Hyperglycemia-induced impairment of the blood-retinal barrier represents the main pathological event in diabetic retinopathy that is elicited by a reduced cellular response to an accumulation of reactive oxygen species (ROS) and increased inflammation. The purpose of the study was to evaluate whether the selective β1-adrenoreceptor (β1-AR) antagonist metoprolol could modulate the inflammatory response to hyperglycemic conditions. For this purpose, human retinal endothelial cells (HREC) were treated with normal (5 mM) or high glucose (25 mM, HG) in the presence of metoprolol (10 μM), epinephrine (1 μM), or both compounds. Metoprolol prevented both the HG-induced reduction of cell viability (MTT assays) and the modulation of the angiogenic potential of HREC (tube formation assays) reducing the TNF-α, IL-1β, and VEGF mRNA levels (qRT-PCR). Moreover, metoprolol prevented the increase in phospho-ERK1/2, phospho-cPLA2, COX2, and protein levels (Western blot) as well as counteracting the translocation of ERK1/2 and cPLA2 (high-content screening). Metoprolol reduced ROS accumulation in HG-stimulated HREC by activating the anti-oxidative cellular response mediated by the Keap1/Nrf2/HO-1 pathway. In conclusion, metoprolol exerted a dual effect on HG-stimulated HREC, decreasing the activation of the pro-inflammatory ERK1/2/cPLA2/COX2 axis, and counteracting ROS accumulation by activating the Keap1/Nrf2/HO-1 pathway.

Vitamin D3 preserves blood retinal barrier integrity in an in vitro model of diabetic retinopathy

“…We evaluated the effects of vitamin D 3 regarding the mRNA levels of inflammatory cytokines, ICAM-1, IL-1β, and TLR-4 in endothelial cells treated with HG. As previously reported, HG treatment led to a significant increase in the pro-inflammatory cytokines mRNA levels, as well as TLR-4 (Xie et al, 2014;Wang et al, 2018;Zhou et al, 2019;Giurdanella et al, 2021). It has been demonstrated that high glucose promotes the activation of TLR (2/4) and, through myeloid differentiation proteins (MyD88)-dependent and -independent signaling pathway, it stimulates the release of inflammatory mediators (Devaraj et al, 2008;Dasu and Jialal, Frontiers in Pharmacology frontiersin.org 2011), which are also significantly increased in the vitreous fluid of DR patients (Boss et al, 2017;Iyer et al, 2021;Wu et al, 2021).…”

Role of apigenin in high glucose-induced retinal microvascular endothelial cell dysfunction via regulating NOX4/p38 MAPK pathway in vitro

“…Oxidative stress has been evidenced as the main target in DR pathophysiology [28] . In addition, the excessive accumulation of ROS is a pivotal factor contributing to retinal endothelial cell dysfunction and inflammation processes under hyperglycemia [29] . Therefore, vascular permeability, neovascularization, oxidative stress and inflammation are the main research directions for discovering therapeutic strategies for the treatment of DR. For example, Yu et al [30] disclosed circ-UBAP2 as a promising therapeutic target for DR as knockdown of circ-UBAP2 relieved HG-induced oxidative stress and vascular dysfunction of HRMECs.…”

Pericytes of Stria Vascularis Are Targets of Cisplatin-Induced Ototoxicity: New Insights into the Molecular Mechanisms Involved in Blood-Labyrinth Barrier Breakdown

“…After treatments, BCPs were lysed as previously described [68]. The protein content of the cell lysate was quantified by the Bradford assay, 40 µg proteins were loaded into polyacrylamide gels, run in SDS-PAGE and blotted as described elsewhere [69].…”