Quercetin attenuates cerebral ischemic injury by inhibiting ferroptosis via Nrf2/HO-1 signaling pathway

AIMS

Ischemic stroke is a severe cerebrovascular disease in which neuronal death continually occurs through multiple forms, including apoptosis, autophagy, pyroptosis and ferroptosis. Quercetin (QRC), as a natural flavonoid compound, has been reported to have pharmacological effects on ischemic injury accompanied by unclear anti-ferroptotic mechanisms. This study is designed to investigate the therapeutic effects of QRC against ferroptosis in ischemic stroke.

MATERIALS AND METHODS

In vivo, the model of MCAO rats were used to assess the protective effect of QRC on cerebral ischemic. Additionally, we constructed oxidative stressed and ferroptotic cell models to explore the effects and mechanisms of QRC on ferroptosis. The related proteins were analysed by western blotting, immunohistochemical and immunofluorescence techniques.

RESULTS

The experiments demonstrated that QRC improves neurological deficits, infarct volume, and pathological features in MCAO rats, also increased the viability of HT-22 cells exposed to H2O2 and erastin. These results, including MDA, SOD, GSH, ROS levels and iron accumulation, indicated that QRC suppresses the generation of lipid peroxides and may involve in the regulatory of ferroptosis. Both in vitro and in vivo, QRC was found to inhibit ferroptosis by up-regulating GPX4 and FTH1, as well as down-regulating ACSL4. Furthermore, we observed that QRC enhances the nuclear translocation of Nrf2 and activates the downstream antioxidative proteins. Importantly, the effect of QRC on ferroptosis can be reversed by the Nrf2 inhibitor ML385.

CONCLUSIONS

This study provides evidence that QRC has a neuroprotective effect by inhibiting ferroptosis, demonstrating the therapeutic potential for cerebral ischemic stroke.

Protective Role of Myricetin and Fisetin Against Nephrotoxicity Caused by Lead Acetate Exposure through Up-regulation of Nrf2/HO-1 Signalling Pathway

The effect of various flavonoids against oxidative stress and inflammation caused by lead exposure has been investigated. However, the protective effects of myricetin (MYC) and fisetin (FST), which are known to have potent antioxidant properties, against nephrotoxicity caused by exposure to lead acetate (LA), the water-soluble form of lead, have not been investigated. Our study investigated the protective role of these flavonoids against LA intoxication-induced nephrotoxicity. In our study, 42 male rats were used. The rats were randomly selected and divided into 6 groups. These groups were: control, LA (100 g/kg), LA + MYC (100 mg/kg), LA + MYC (200 mg/kg), LA + FST (100 mg/kg) and LA + FST (200 mg/kg). All chemicals were administered daily by gavage for 28 days. According to the experimental protocol, the animals were sacrificed and their kidney tissues were isolated. Serum biochemical parameters, histological examinations, levels of several trace elements, oxidative stress and inflammatory parameters at both biochemical and molecular levels in kidney tissues were examined. After LA administration, tissue lead levels increased and zinc levels decreased. This situation was reversed by MYC and FST treatment. Oxidative stress and inflammatory response were increased in the kidney tissue of LA-treated rats and renal function was impaired. It was observed that both doses of MYC and high dose of FST could prevent nephrotoxicity. Oral administration of both doses of MYC and high dose FST ameliorated the changes in biochemical, oxidative and inflammatory parameters. Restoration of normal renal tissue architecture was also demonstrated by histological studies. MYC and FST were found to have promising biological activity against LA-induced nephrotoxicity, acting by attenuating inflammation and oxidative stress and improving antioxidant status.

Cu-Zn SOD suppresses epilepsy in pilocarpine-treated rats and alters SCN2A/Nrf2/HO-1 expression

Objective

Copper-zinc superoxide dismutase (Cu-Zn SOD) is downregulated in epilepsy, however, the role of Cu-Zn SOD in epilepsy remains unclear.

Methods

Based on the pilocarpine hydrochloride-induced rat model of epilepsy, cortical-striatum brain slices of rats were examined based on field excitatory post-synaptic potentials. Pathological changes were observed by transmission electron microscope. Also using SH-SY5Y cells, flow cytometry and TUNEL staining were applied to investigate cell apoptosis, and ELISA was applied to detect SOD activity. In addition, qRT-PCR and western blot were performed to detect SCN2A/Nrf2/HO-1 gene and protein expression levels, respectively.

Results

Cu-Zn SOD over-expression suppressed epilepsy in vivo. In addition, Cu-Zn SOD knockdown notably decreased SOD activity and induced apoptosis in SH-SY5Y cells. Moreover, Cu-Zn SOD silencing decreased the levels of SCN2A, Nrf2 and HO-1. Lastly, Cu-Zn SOD was shown to modulate the NaV1.2/Nrf2/HO-1 axis in rats.

Significance

In this model, Cu-Zn SOD attenuated epilepsy and was shown to alter the expression level of proteins of the NaV1.2 /Nrf2/HO-1 signalling pathway, indicating that Cu-Zn SOD might be a target for the treatment of epilepsy.

Knockdown of ALK7 inhibits high glucose-induced oxidative stress and apoptosis in retinal pigment epithelial cells

Diabetic retinopathy (DR) is one of the diabetic complications associated with hyperglycaemia-mediated oxidative stress. Activin receptor-like kinase 7 (ALK7) has been proven to be a potential therapeutic approach for diabetic cardiomyopathy, which is another diabetic complication. However, the role of ALK7 in DR remains unclear. In the current study, ALK7 was found to be up-regulated in clinical samples from DR patients and high glucose (HG)-induced human retinal pigment epithelial cells (ARPE-19). In vitro studies demonstrated that knockdown of ALK7 in ARPE-19 cells through transfection with siRNA-ALK7 (si-ALK7) improved cell viability in HG-induced ARPE-19 cells. Knockdown of ALK7 suppressed HG-induced reactive oxygen species (ROS) production, as well elevating the activities of superoxide dismutase (SOD), catalase (CAT), and glutathione (GSH) in ARPE-19 cells. The number of apoptotic cells was significantly decreased after transfection with si-ALK7. ALK7 knockdown also caused a significant decrease in bax expression and an increase in bcl-2 expression in HG-induced ARPE-19 cells. In addition, ALK7 knockdown resulted in remarkable increase in the expressions of nuclear factor (erythroid-derived 2)-like 2 (Nrf2) and heme oxygenase-1 (HO-1) in ARPE-19 cells in response to HG induction. Taken together, knockdown of ALK7 protected ARPE-19 cells from HG-induced oxidative injury, which might be mediated by the activation of the Nrf2/HO-1 signalling pathway.