TIMP3 attenuates cerebral ischemia/reperfusion-induced apoptosis and oxidative stress in neurocytes by regulating the AKT pathway

A matrix metalloproteinase-responsive hydrogel system controls angiogenic peptide release for repair of cerebral ischemia/reperfusion injury

JOURNAL/nrgr/04.03/01300535-202502000-00028/figure1/v/2024-05-28T214302Z/r/image-tiff Vascular endothelial growth factor and its mimic peptide KLTWQELYQLKYKGI (QK) are widely used as the most potent angiogenic factors for the treatment of multiple ischemic diseases. However, conventional topical drug delivery often results in a burst release of the drug, leading to transient retention (inefficacy) and undesirable diffusion (toxicity) in vivo. Therefore, a drug delivery system that responds to changes in the microenvironment of tissue regeneration and controls vascular endothelial growth factor release is crucial to improve the treatment of ischemic stroke. Matrix metalloproteinase-2 (MMP-2) is gradually upregulated after cerebral ischemia. Herein, vascular endothelial growth factor mimic peptide QK was self-assembled with MMP-2-cleaved peptide PLGLAG (TIMP) and customizable peptide amphiphilic (PA) molecules to construct nanofiber hydrogel PA-TIMP-QK. PA-TIMP-QK was found to control the delivery of QK by MMP-2 upregulation after cerebral ischemia/reperfusion and had a similar biological activity with vascular endothelial growth factor in vitro. The results indicated that PA-TIMP-QK promoted neuronal survival, restored local blood circulation, reduced blood-brain barrier permeability, and restored motor function. These findings suggest that the self-assembling nanofiber hydrogel PA-TIMP-QK may provide an intelligent drug delivery system that responds to the microenvironment and promotes regeneration and repair after cerebral ischemia/reperfusion injury.

NDRG2 alleviates photoreceptor apoptosis by regulating the STAT3/TIMP3/MMP pathway in mice with retinal degenerative disease

Photoreceptor apoptosis is the main pathological feature of retinal degenerative diseases; however, the underlying molecular mechanism has not been elucidated. Recent studies have shown that N-myc downstream regulated gene 2 (NDRG2) exerts a neuroprotective effect on the brain and spinal cord. In addition, our previous studies have confirmed that NDRG2 is expressed in mouse retinal photoreceptors and counteracts N-methyl-N-nitrosourea (MNU)-induced apoptosis. However, the underlying molecular mechanism remains unclear. In this study, we observed that the expression of NDRG2 was not only significantly inhibited in photoreceptors after MNU treatment but also after hydrogen peroxide treatment, and photoreceptor apoptosis was alleviated or aggravated after overexpression or knockdown of NDRG2 in the 661W photoreceptor cell line, respectively. The apoptosis inhibitor Z-VAD-FMK rescued photoreceptor apoptosis induced by MNU after NDRG2 knockdown. Next, we screened and identified tissue inhibitor of metalloproteinases 3 (TIMP3) as the downstream molecule of NDRG2 in 661W cells by using quantitative real-time polymerase chain reaction. TIMP3 exerts a neuroprotective effect by inhibiting the expression of matrix metalloproteinases (MMPs). Subsequently, we found that signal transducer and activator of transcription 3 (STAT3) mediated the NDRG2-associated regulation of TIMP3. Finally, we overexpressed NDRG2 in mouse retinal tissues by intravitreally injecting an adeno-associated virus with mouse NDRG2 in vivo. Results showed that NDRG2 upregulated the expression of phospho-STAT3 (p-STAT3) and TIMP3, while suppressing MNU-induced photoreceptor apoptosis and MMP expression. Our findings revealed how NDRG2 regulates the STAT3/TIMP3/MMP pathway and uncovered the molecular mechanism underlying its neuroprotective effect on mouse retinal photoreceptors.

Proteomic analysis of Biliverdin protected cerebral ischemia-reperfusion injury in rats

Biliverdin, a heme metabolite, has been previously reported to alleviate cerebral ischemic reperfusion injury (CIRI). However, the alterations of brain proteome profiles underlying this treatment remain elusive. The objective of this study is to analyze the differential protein expression profile in cerebral cortex of rats involved in anti-CIRI effects of Biliverdin, providing experimental foundation for searching specific marker proteins. Rat model of MCAO/R was established, HE staining, TTC staining, TUNEL staining, and neurological behavioral examination, corner turning test, adhesive removal test, were performed to validate the effects of Biliverdin, and the results indicated that Biliverdin plays a significant role in alleviating CIRI. Furthermore, proteomic analysis of brain tissues of rats subjected to CIRI following Biliverdin treatment was performed using an integrated TMT-based quantitative proteomic approach coupled with LC-MS/MS technology to clarify the comprehensive mechanisms of Biliverdin in CIRI. First, we conducted strict quality control data for TMT experiments. Finally, a total of 7366 proteins were identified, of which 95 proteins were differentially expressed (DEPs) between the CIRI group and the Sham group and 52 between the CIRI and BV groups. In addition, two overlapping proteins among the 147 DEPs, Atg4c and Camlg, were validated by RT-qPCR and western blotting, and their levels were consistent with the results of TMT analysis. Taken together, the current findings firstly mapped comprehensive proteomic changes after CIRI treated with Biliverdin, providing a foundation for developing potentially therapeutic targets of anti-CIRI of Biliverdin and clinically prognostic biomarkers of stroke.

Activation of the Akt/FoxO3 signaling pathway enhances oxidative stress-induced autophagy and alleviates brain damage in a rat model of ischemic stroke

Autophagy has been implicated in stroke. Our previous study showed that the FoxO3 transcription factor promotes autophagy after transient cerebral ischemia/reperfusion (I/R). However, whether the Akt/FoxO3 signaling pathway plays a regulatory role in autophagy in cerebral I/R-induced oxidative stress injury is still unclear. The present study aims to investigate the effects of the Akt/FoxO3 signaling pathway on autophagy activation and neuronal injury in vitro and in vivo. By employing LY294002 or insulin to regulate the Akt/FoxO3 signaling pathway, we found that insulin pretreatment increased cell viability, decreased reactive oxygen species production, and enhanced the expression of antiapoptotic and autophagy-related proteins following H₂O₂ injury in HT22 cells. In addition, insulin significantly decreased neurological deficit scores and infarct volume and increased the expression of antiapoptotic and autophagy-related proteins following I/R injury in rats. However, LY294002 showed the opposite effects under these conditions. Altogether, these results indicate that Akt/FoxO3 signaling pathway activation inhibited oxidative stress-mediated cell death through activation of autophagy. Our study supports a critical role for the Akt/FoxO3 signaling pathway in autophagy activation in stroke.

Laser speckle contrast imaging for blood flow monitoring in predicting outcomes after cerebral ischemia-reperfusion injury in mice

BACKGROUND

In the treatment of ischemic cerebral stroke (ICS), most conventional treatments, including carotid endarterectomy and carotid artery stenting, may cause cerebral ischemia-reperfusion injury (CIRI). For treated ICS patients, changes in cerebral blood flow are directly related to brain function. At present, computed tomography perfusion, dynamic susceptibility contrast-enhanced perfusion weighted imaging and magnetic resonance arterial spin labeling perfusion imaging are used to monitor cerebral blood flow, but they still have some limitations. Our study aimed to monitor the changes in cerebral cortical blood flow by laser speckle contrast imaging (LSCI) in CIRI model mice and to propose a new method for predicting outcomes after CIRI. C57BL/6 N mice were used to establish a mouse CIRI model based on a modified thread-occlusion method and divided into a good outcome group and a poor outcome group according to survival within 7 days. The cerebral cortical blood flow of the area supplied by the left middle cerebral artery was monitored by LSCI at baseline (before modeling), 1 h after ischemia, immediately after reperfusion and 24 h after reperfusion. Then, the brains of the mice were removed immediately and stained with hematoxylin and eosin to observe the pathological changes in brain neurons.

RESULTS

The cerebral cortical blood flow in the poor outcome group was obviously reduced compared with that less in the good outcome group at 24 h after reperfusion (180.8 ± 20.9 vs. 113.9 ± 6.4, p = 0.001), and at 24 h after reperfusion, the cerebral cortical blood flow was negatively correlated with the severity of brain tissue injury (p = - 0.710, p = 0.010).

CONCLUSIONS

LSCI can monitor the changes in cerebral cortical blood flow during CIRI in mice and could be used as a feasible method for predicting outcomes after CIRI in mice.

Novel Flavan-3,4-diol vernicidin B from Toxicodendron Vernicifluum (Anacardiaceae) as potent antioxidant via IL-6/Nrf2 cross-talks pathways

BACKGROUND

Oxidative stress is considered to be a pathological factor of various neurodegenerative diseases. Studies have confirmed the antioxidant activity of T. vernicifluum. However, the main active components responsible for antioxidant activity remain unknown.

OBJECTIVE

The aim of this study is to explore the activities of vernicidin B on oxidative stress injury induced by H₂O₂ in SH-SY5Y cells, and the underlying mechanism of vernicidin B in oxidative stress-related neurological diseases is further discussed.

METHODS

Various separation methods were used to isolate and identify the compounds in an EtOAc extract of T. vernicifluum. The structures of the isolates were clarified by HR-TOF-MS and 1D/2D NMR data and compared with findings in previous literature. The MTT assay was used to evaluate the potential antioxidant activity of the isolated flavonoids. The apoptosis rate, mitochondrial reactive oxygen species (ROS) level and mitochondrial potential were measured by flow cytometry and fluorescence microscope. The levels of related proteins were detected by Western blotting.

RESULTS

Four new flavan-3,4-diols (1-4, vernicidins A-D) and 11 known flavonoids (5-15) were purified from the EtOAc extract of T. vernicifluum. Among these compounds, vernicidin B showed the most promising potential for protecting SH-SY5Y cells from H₂O₂-induced oxidative stress. Moreover, pretreatment with vernicidin B decreased ROS production and mitochondrial membrane potential and significantly attenuated H₂O₂-induced apoptosis in a dose-dependent manner. Mechanistically, the antioxidant stress activities of vernicidin B were confirmed to be related to the IL-6/Nrf2 cross-talks pathway and its downstream pathways, including PI3K/Akt/mToR-Gsk3β, JAK2/STAT3 and MAPKs.

CONCLUSIONS

Our findings suggested that vernicidin B can improve the oxidative stress injury induced by H₂O₂ through IL-6/Nrf2 cross-talks pathway, indicating that it may be a potential candidate drug for the treatment of oxidative stress-related neurodegenerative diseases.