Metformin prevents methylglyoxal-induced apoptosis by suppressing oxidative stress in vitro and in vivo

Abstract

Methylglyoxal (MGO) is an active metabolite of glucose and plays a prominent role in the pathogenesis of diabetic vascular complications, including endothelial cell apoptosis induced by oxidative stress. Metformin (MET), a widely prescribed antidiabetic agent, appears to reduce excessive reactive oxygen species (ROS) generation and limit cell apoptosis. However, the molecular mechanisms underlying this process are still not fully elucidated. We reported here that MET prevents MGO-induced apoptosis by suppressing oxidative stress in vitro and in vivo. Protein expression and protein phosphorylation were investigated using western blotting, ELISA, and immunohistochemical staining, respectively. Cell viability and apoptosis were assessed by the MTT assay, TUNEL staining, and Annexin V-FITC and propidium iodide double staining. ROS generation and mitochondrial membrane potential (MMP) were measured with fluorescent probes. Our results revealed that MET prevented MGO-induced HUVEC apoptosis, inhibited apoptosis-associated biochemical changes such as loss of MMP, the elevation of the Bax/Bcl-2 ratio, and activation of cleaved caspase-3, and attenuated MGO-induced mitochondrial morphological alterations in a dose-dependent manner. MET pretreatment also significantly suppressed MGO-stimulated ROS production, increased signaling through the ROS-mediated PI3K/Akt and Nrf2/HO-1 pathways, and markedly elevated the levels of its downstream antioxidants. Finally, similar results were obtained in vivo, and we demonstrated that MET prevented MGO-induced oxidative damage, apoptosis, and inflammation. As expected, MET reversed MGO-induced downregulation of Nrf2 and p-Akt. In addition, a PI3K inhibitor (LY-294002) and a Nrf2 inhibitor (ML385) observably attenuated the protective effects of MET on MGO-induced apoptosis and ROS generation by inhibiting the Nrf2/HO-1 pathways, while a ROS scavenger (NAC) and a permeability transition pores inhibitor (CsA) completely reversed these effects. Collectively, these findings broaden our understanding of the mechanism by which MET regulates apoptosis induced by MGO under oxidative stress conditions, with important implications regarding the potential application of MET for the treatment of diabetic vascular complications.

Dicarbonyl-Dependent Modification of LDL as a Key Factor of Endothelial Dysfunction and Atherosclerotic Vascular Wall Damage

“…Moreover, the data presented in this review indicate that in order to suppress atherogenesis and endothelial dysfunction it is necessary to inhibit not only (and perhaps not so much) the accumulation of primary products (LOOH) in LDL, but also the accumulation of secondary products of free radical oxidation—low molecular weight dicarbonyls. Positive examples of influencing the intensity of free radical oxidation using biguanides—dicarbonyl scavengers [ 101 , 113 , 114 , 115 ] and aldehyde-binding imidazole-containing peptides [ 116 , 117 ] already exist. In particular, the use of biguanides significantly suppressed the manifestation of oxidative and carbonyl stress in diabetic patients without the administration of any antioxidants (the so-called “quasi-antioxidant effect”) [ 101 ].…”

Is metformin a possible treatment for diabetic neuropathy?

“…Intrathecal injection of metformin also significantly reduced the upregulated MGO in the dorsal horn and mechanical pain induced by bortezomib treatment, which may be related to RAGE/STAT3 signalling pathway 68 . Metformin also reduced MGO‐induced apoptosis by inhibiting oxidative stress in vivo and in vitro 69 . Taken together, the data suggested that metformin, as an MGO scavenger, may serve as a disease reliever in PDPN.…”

“… 68 Metformin also reduced MGO‐induced apoptosis by inhibiting oxidative stress in vivo and in vitro. 69 Taken together, the data suggested that metformin, as an MGO scavenger, may serve as a disease reliever in PDPN.…”

Vaccarin alleviates endothelial inflammatory injury in diabetes by mediating miR-570-3p/HDAC1 pathway

“…In addition, it was found that the production of MDA increased and the activity of GSH-Px decreased in HG-induced HUVEC cells, vaccarin treatment could reverse these phenomena ( Figures 4F, G ), indicating that vaccarin could also play an anti-inflammatory role in vitro . Metformin (MET) had been widely proven to relieve inflammatory injury in T2DM( Karam and Radwan 2019 ; Raj, Natarajan et al, 2021 ; Wang, Wang et al, 2022 ). Therefore, we used metformin as a positive control to compare the effects of vaccarin and found that the effect of vaccarin on the inflammatory injury was similar to that of metformin ( Figures 4A–G ).…”