Naringin Attenuates Cerebral Ischemia-Reperfusion Injury Through Inhibiting Peroxynitrite-Mediated Mitophagy Activation

Naringin attenuates cerebral ischemia-reperfusion injury in rats by inhibiting endoplasmic reticulum stress

Objective

This investigation was carried out with an aim of exploring neuroprotection by naringin (Nar) in rats with cerebral ischemia-reperfusion (CI/R) injury and its mechanism.

Methods

Rats were grouped into ischemia-reperfusion (I/R), sham operation (Sham), nimodipine control (NIM), and different doses of Nar (Nar-L, Nar-M, Nar-H) groups. With Zea Longa score for assessment of neurological deficits, dry and wet method for measurement of brain tissue water content, and (2,3,5-triphenyltetrazolium chloride) TTC staining for determination of cerebral infarction volume, the related parameters were obtained and compared. Subsequently, ELISA was introduced to detect levels of proinflammatory cytokines (TNF-α, IL-8) and anti-inflammatory cytokine (IL-10) in the serum as well as superoxide dismutase (SOD) and malondialdehyde (MDA) activities in brain tissue. Western blot was applied to evaluate endoplasmic reticulum stress (ERS)-related proteins expression, including glucose-regulated protein 78 (GRP78), C/EBP homologous protein (CHOP), caspase-12, and activating transcription factor 6 (ATF-6).

Results

Nar significantly alleviated nerve injury and decreased brain tissue water content and brain infraction volume in CI/R injury rats in a concentration-dependent manner. Reduction of TNF-α, IL-8 as well as MDA content and elevation of IL-10 as well as SOD activity were confirmed to be caused by Nar treatment in a concentration-dependent manner. Meanwhile, ERS-related proteins also markedly decreased in the Nar groups.

Conclusion

Nar may achieve neuroprotection and alleviation of CI/R injury by anti-inflammation, anti-oxidation, and inhibiting ERS, and its efficacy is concentration-dependent.

Neuroprotective Phytochemicals in Experimental Ischemic Stroke: Mechanisms and Potential Clinical Applications

Ischemic stroke is a challenging disease with high mortality and disability rates, causing a great economic and social burden worldwide. During ischemic stroke, ionic imbalance and excitotoxicity, oxidative stress, and inflammation are developed in a relatively certain order, which then activate the cell death pathways directly or indirectly via the promotion of organelle dysfunction. Neuroprotection, a therapy that is aimed at inhibiting this damaging cascade, is therefore an important therapeutic strategy for ischemic stroke. Notably, phytochemicals showed great neuroprotective potential in preclinical research via various strategies including modulation of calcium levels and antiexcitotoxicity, antioxidation, anti-inflammation and BBB protection, mitochondrial protection and antiapoptosis, autophagy/mitophagy regulation, and regulation of neurotrophin release. In this review, we summarize the research works that report the neuroprotective activity of phytochemicals in the past 10 years and discuss the neuroprotective mechanisms and potential clinical applications of 148 phytochemicals that belong to the categories of flavonoids, stilbenoids, other phenols, terpenoids, and alkaloids. Among them, scutellarin, pinocembrin, puerarin, hydroxysafflor yellow A, salvianolic acids, rosmarinic acid, borneol, bilobalide, ginkgolides, ginsenoside Rd, and vinpocetine show great potential in clinical ischemic stroke treatment. This review will serve as a powerful reference for the screening of phytochemicals with potential clinical applications in ischemic stroke or the synthesis of new neuroprotective agents that take phytochemicals as leading compounds.

The role and mechanism of citrus flavonoids in cardiovascular diseases prevention and treatment

Cardiovascular diseases (CVDs) have been ranked as the leading cause of death in the world, whose global incidence is increasing year by year. Citrus, one of the most popular fruits in the world, is rich in flavonoids. Citrus flavonoids attract special attention due to a variety of biological activities, especially in the prevention and treatment of CVDs. The research progress of citrus flavonoids on CVDs have been constantly updated, but relatively fragmented, which needed to be systematically summarized. Hence, the recent research about citrus flavonoids and CVDs were reviewed, including the types and in vivo processes of citrus flavonoids, epidemiology study and mechanism on prevention and treatment of CVDs by citrus flavonoids. This review would provide a theoretical basis for the citrus flavonoids research and a new idea in the citrus industry development and application.

Danggui-Shaoyao-San (DSS) Ameliorates Cerebral Ischemia-Reperfusion Injury via Activating SIRT1 Signaling and Inhibiting NADPH Oxidases

Danggui-Shayao-San (DSS) is a famous Traditional Chinese Medicine formula that used for treating pain disorders and maintaining neurological health. Recent studies indicate that DSS has neuroprotective effects against ischemic brain damage but its underlining mechanisms remain unclear. Herein, we investigated the neuroprotective mechanisms of DSS for treating ischemic stroke. Adult male Sprague-Dawley (S.D.) rats were subjected to 2 h of middle cerebral artery occlusion (MCAO) plus 22 h of reperfusion. Both ethanol extract and aqueous extract of DSS (12 g/kg) were orally administrated into the rats at 30 min prior to MCAO ischemic onset. We found that 1) ethanol extract of DSS, instead of aqueous extract, reduced infarct sizes and improved neurological deficit scores in the post-ischemic stroke rats; 2) Ethanol extract of DSS down-regulated the expression of the cleaved-caspase 3 and Bax, up-regulated bcl-2 and attenuated apoptotic cell death in the ischemic brains; 3) Ethanol extract of DSS decreased the production of superoxide and peroxynitrite; 4) Ethanol extract of DSS significantly down-regulated the expression of p67^phox but has no effect on p47^phox and iNOS statistically. 5) Ethanol extract of DSS significantly up-regulated the expression of SIRT1 in the cortex and striatum of the post-ischemic brains; 6) Co-treatment of EX527, a SIRT1 inhibitor, abolished the DSS’s neuroprotective effects. Taken together, DSS could attenuate oxidative/nitrosative stress and inhibit neuronal apoptosis against cerebral ischemic-reperfusion injury via SIRT1-dependent manner.

Autophagy and Mitophagy as Essential Components of Atherosclerosis

Cardiovascular disease (CVD) is one of the greatest health problems affecting people worldwide. Atherosclerosis, in turn, is one of the most common causes of cardiovascular disease. Due to the high mortality rate from cardiovascular diseases, prevention and treatment at the earliest stages become especially important. This requires developing a deep understanding of the mechanisms underlying the development of atherosclerosis. It is well-known that atherogenesis is a complex multi-component process that includes lipid metabolism disorders, inflammation, oxidative stress, autophagy disorders and mitochondrial dysfunction. Autophagy is a cellular control mechanism that is critical to maintaining health and survival. One of the specific forms of autophagy is mitophagy, which aims to control and remove defective mitochondria from the cell. Particularly defective mitophagy has been shown to be associated with atherogenesis. In this review, we consider the role of autophagy, focusing on a special type of it—mitophagy—in the context of its role in the development of atherosclerosis.

Naringin Exhibits Mas Receptor-Mediated Neuroprotection Against Amyloid Beta-Induced Cognitive Deficits and Mitochondrial Toxicity in Rat Brain

Alzheimer's disease (AD) is a progressive neurodegenerative disorder with clinical manifestation of loss in cognitive functions in an individual. Though several drug candidates have been developed in the management of AD, an alternative option is still required due to serious adverse effects of the former. Recently, naringin exerts therapeutic benefits through rennin angiotensin system in experimental animals. However, its report  on Mas receptor-mediated action against amyloid beta (Aβ)-induced mitochondrial dysfunction in AD-like animals is lacking. The experimental dementia was induced in the male rats by intracerebroventricular administration of Aβ_(1-42) on day 1 (D-1) of the experimental schedule of 14 days. Naringin treatment for 14 days attenuated Aβ-induced cognitive impairments of the animals in Morris water maze (MWM) and Y-maze tests. Further, naringin ameliorated the Aβ-induced cholinergic dysfunction in terms of decrease in the activity of choline acetyl transferase (ChAT) and level of acetylcholine (ACh) and increase in the activity of acetylcholine esterase (AChE) in rat hippocampus, prefrontal cortex, and amygdala. Furthermore, naringin attenuated Aβ-induced decrease in mitochondrial function, integrity, and bioenergetics in all the brain regions. Naringin also attenuated Aβ-induced increase in mitochondrial and cytosolic calcium level in all the brain regions. Moreover, naringin reversed Aβ-induced increase in apoptosis and level of mitochondrial calcium uniporter and decrease in the level of hemeoxygenase-1 in all the brain regions. On the contrary, A779 significantly abolished the therapeutic potential of naringin on Aβ-induced alteration in behavioral, biochemical, and molecular observations in these experimental animals. Thus, these observations indicate that naringin could be potential alternative in the management of AD.

Fundamental Mechanisms of the Cell Death Caused by Nitrosative Stress

Nitrosative stress, as an important oxygen metabolism disorder, has been shown to be closely associated with cardiovascular diseases, such as myocardial ischemia/reperfusion injury, aortic aneurysm, heart failure, hypertension, and atherosclerosis. Nitrosative stress refers to the joint biochemical reactions of nitric oxide (NO) and superoxide (O₂ ^-) when an oxygen metabolism disorder occurs in the body. The peroxynitrite anion (ONOO^-) produced during this process can nitrate several biomolecules, such as proteins, lipids, and DNA, to generate 3-nitrotyrosine (3-NT), which further induces cell death. Among these, protein tyrosine nitration and polyunsaturated fatty acid nitration are the most studied types to date. Accordingly, an in-depth study of the relationship between nitrosative stress and cell death has important practical significance for revealing the pathogenesis and strategies for prevention and treatment of various diseases, particularly cardiovascular diseases. Here, we review the latest research progress on the mechanisms of nitrosative stress-mediated cell death, primarily involving several regulated cell death processes, including apoptosis, autophagy, ferroptosis, pyroptosis, NETosis, and parthanatos, highlighting nitrosative stress as a unique mechanism in cardiovascular diseases.

The Role of Mitophagy in Ischemic Stroke

Mitochondria are important places for eukaryotes to carry out energy metabolism and participate in the processes of cell differentiation, cell information transmission, and cell apoptosis. Autophagy is a programmed intracellular degradation process. Mitophagy, as a selective autophagy, is an evolutionarily conserved cellular process to eliminate dysfunctional or redundant mitochondria, thereby fine-tuning the number of mitochondria and maintaining energy metabolism. Many stimuli could activate mitophagy to regulate related physiological processes, which could ultimately reduce or aggravate the damage caused by stimulation. Stroke is a common disease that seriously affects the health and lives of people around the world, and ischemic stroke, which is caused by cerebral vascular stenosis or obstruction, accounts for the vast majority of stroke. Abnormal mitophagy is closely related to the occurrence, development and pathological mechanism of ischemic stroke. However, the exact mechanism of mitophagy involved in ischemic stroke has not been fully elucidated. In this review, we discuss the process and signal pathways of mitophagy, the potential role of mitophagy in ischemic stroke and the possible signal transduction pathways. It will help deepen the understanding of mitophagy and provide new ideas for the treatment of ischemic stroke.

Rehmapicroside ameliorates cerebral ischemia-reperfusion injury via attenuating peroxynitrite-mediated mitophagy activation

Peroxynitrite (ONOO^-)-mediated mitophagy activation represents a vital pathogenic mechanism in ischemic stroke. Our previous study suggests that ONOO^- mediates Drp1 recruitment to the damaged mitochondria for excessive mitophagy, aggravating cerebral ischemia/reperfusion injury and the ONOO^--mediated mitophagy activation could be a crucial therapeutic target for improving outcome of ischemic stroke. In the present study, we tested the neuroprotective effects of rehmapicroside, a natural compound from a medicinal plant, on inhibiting ONOO^--mediated mitophagy activation, attenuating infarct size and improving neurological functions by using the in vitro cultured PC12 cells exposed to oxygen glucose deprivation with reoxygenation (OGD/RO) condition and the in vivo rat model of middle cerebral artery occlusion (MCAO) for 2 h of transient cerebral ischemia plus 22 h of reperfusion. The major discoveries include following aspects: (1) Rehmapicroside reacted with ONOO^- directly to scavenge ONOO^-; (2) Rehmapicroside decreased O₂^- and ONOO^-, up-regulated Bcl-2 but down-regulated Bax, Caspase-3 and cleaved Caspase-3, and down-regulated PINK1, Parkin, p62 and the ratio of LC3-II to LC3-I in the OGD/RO-treated PC12 cells; (3) Rehmapicroside suppressed 3-nitrotyrosine formation, Drp1 nitration as well as NADPH oxidases and iNOS expression in the ischemia-reperfused rat brains; (4) Rehmapicroside prevented the translocations of PINK1, Parkin and Drp1 into the mitochondria for mitophagy activation in the ischemia-reperfused rat brains; (5) Rehmapicroside ameliorated infarct sizes and improved neurological deficit scores in the rats with transient MCAO cerebral ischemia. Taken together, rehmapicroside could be a potential drug candidate against cerebral ischemia-reperfusion injury, and its neuroprotective mechanisms could be attributed to inhibiting the ONOO^--mediated mitophagy activation.

Improvement of cerebral ischemia-reperfusion injury by L-3-n-butylphthalide through promoting angiogenesis

Cerebral ischemia/reperfusion (I/R) injury may lead to a poor prognosis for ischemic stroke patients after reperfusion therapy, and currently, lacks effective therapeutic intervention. This study aimed to investigate the effects of L-3-n-butylphthalide (L-NBP) on cerebral I/R injury in rats. Rat models of cerebral I/R injury were established using the middle cerebral artery occlusion/refusion (MACO/R) surgery and were administrated intragastrically with L-NBP or vehicle. We found that L-NBP attenuated the histological damages and reduced the brain hematoma in MACO/R rats. L-NBP also significantly improved the neurological function, alleviated the brain edema, and reduced the permeability of blood-brain barrier of MACO/R rats. Moreover, we detected that L-NBP considerably facilitated microvessel formation in the lesion area of brain in MACO/R rats. Finally, we found that L-NBP significantly increased the protein and mRNA expression levels of Nrf2, HIF-1α, and VEGF in the brain of MACO/R rats. In conclusion, our results demonstrated that L-NBP exerted significant beneficial effects on cerebral I/R injury in rats through promoting angiogenesis, which may be associated with the activation of Nrf2/HIF-1α/VEGF signaling pathway. Our results suggested that L-NBP could be a potential therapeutic drug for cerebral I/R injury.

Melatonin and regulation of autophagy: Mechanisms and therapeutic implications

Mitochondria are essential subcellular units that generate basic energy for the cell, as well as influence Ca²⁺ flux, apoptosis, and cell signaling. Mitophagy can selectively remove impaired mitochondria to preserve mitochondrial function, which is crucial for normal cellular maintenance. Mitochondrial dysfunction and mitophagy are widely reported to be linked to various pathogeneses. In addition, there is increasing evidence regarding the beneficial role of melatonin in the regulation and intervention of mitophagy progression. In this review, we focus on specific pathological conditions, including ischemia/reperfusion injury (IRI), cancer and neurodegenerative diseases, and elucidate the essential role of melatonin in the modulation of mitophagy in each of these distinct disorders.

Melatonin attenuates ovarian ischemia reperfusion injury in rats by decreasing oxidative stress index and peroxynitrite

Background/aim

To evaluate the protective effect of melatonin on ovarian ischemia reperfusion injury in a rat model.

Materials and methods

Forty-eight rats were separated equally into 6 groups. Group 1: sham; Group 2: surgical control with 3-h bilateral ovarian torsion and detorsion; Group 3: intraperitoneal 5% ethanol (1 mL) just after detorsion (as melatonin was dissolved in ethanol); Group 4: 10 mg/kg intraperitoneal melatonin 30 min before 3-h torsion; Group 5:10 mg/kg intraperitoneal melatonin just after detorsion; Group 6:10 mg/kg intraperitoneal melatonin 30 min before torsion and just after detorsion. Both ovaries and blood samples were obtained 7 days after detorsion for histopathological and biochemical analysis.

Results

In Group 1, serum levels of total oxidant status (TOS) (μmol H2O2 equivalent/g wet tissue)were significantly lower than in Group2 (P = 0.0023), while tissue TOS levels were lower than in Group 3 (P = 0.0030). Similarly, serum and tissue levels of peroxynitrite in Group 6were significantly lower than those ofGroup 2 (P = 0.0023 and P = 0.040, respectively). Moreover, serum oxidative stress index (OSI) (arbitrary unit) levels were significantly increased in Group 2 when compared to groups 1 and 6 (P = 0.0023 and P= 0.0016, respectively) and in Group 3 with respect to groups 1, 4, 5, and 6 (P = 0.0023, P = 0.0026, P = 0.0008, and P = 0.0011, respectively). Furthermore, there was a significant decrease in histopathological scores including follicular degeneration, vascular congestion, hemorrhage, and inflammation in the melatonin and sham groups in comparison with control groups. Additionally, primordial follicle count was significantly higher in Group 6 than in Group 2 (P = 0.0002).

Conclusion

Melatonin attenuates ischemia reperfusion damage in a rat torsion/detorsion model by improving histopathological and biochemical findings including OSI and peroxynitrite.

A sphingosine kinase 2-mimicking TAT-peptide protects neurons against ischemia-reperfusion injury by activating BNIP3-mediated mitophagy

We have previously shown that sphingosine kinase 2 (SPK2) interacts with Bcl-2 via its BH3 domain, activating autophagy by inducing the dissociation of Beclin-1/Bcl-2 complexes, and that a TAT-SPK2 peptide containing the BH3 domain of SPK2 protects neurons against ischemic injury. The goals of the present study were to establish the functional significance of these findings, by testing whether TAT-SPK2 was effective in a mouse model of ischemic stroke, and to explore potential underlying mechanisms. Mice were administered with TAT-SPK2 by intraperitoneal injection before or after transient middle cerebral artery occlusion (tMCAO). Infarct volume, neurological deficit and brain water content were assessed 24 h after reperfusion. Mitophagy inhibitor Mdivi-1 and BNIP3 siRNAs were used to examine the involvement of BNIP3-dependent mitophagy in the neuroprotection of TAT-SPK2. Mitophagy was quantified by immunoblotting, immunofluorescence and electron microscopy. The interaction between TAT-SPK2 and Bcl-2, Bcl-2 and BNIP3 was detected by co-immunoprecipitation. In the tMCAO model, pre-treatment with TAT-SPK2 significantly reduced infarct volume, improved neurological function and decreased brain edema. Neuroprotection by TAT-SPK2 was still seen when the peptide was administered 3 h after reperfusion. TAT-SPK2 also significantly improved functional recovery and reduced long-term brain atrophy of the ischemic hemisphere 30 days after administration. Our studies further showed that TAT-SPK2 directly binds to Bcl-2 and disrupts Bcl-2/Beclin-1 or Bcl-2/BNIP3 complexes to induce mitophagy. These results suggest that TAT-SPK2 protects neurons against ischemia reperfusion injury by activating BNIP3-mediated mitophagy. Agents exploiting this molecular mechanism are potential candidates for the treatment of ischemic stroke.

Complex interplay between autophagy and oxidative stress in the development of pulmonary disease

The autophagic pathway involves the encapsulation of substrates in double-membraned vesicles, which are subsequently delivered to the lysosome for enzymatic degradation and recycling of metabolic precursors. Autophagy is a major cellular defense against oxidative stress, or related conditions that cause accumulation of damaged proteins or organelles. Selective forms of autophagy can maintain organelle populations or remove aggregated proteins. Dysregulation of redox homeostasis under pathological conditions results in excessive generation of reactive oxygen species (ROS), leading to oxidative stress and the associated oxidative damage of cellular components. Accumulating evidence indicates that autophagy is necessary to maintain redox homeostasis. ROS activates autophagy, which facilitates cellular adaptation and diminishes oxidative damage by degrading and recycling intracellular damaged macromolecules and dysfunctional organelles. The cellular responses triggered by oxidative stress include the altered regulation of signaling pathways that culminate in the regulation of autophagy. Current research suggests a central role for autophagy as a mammalian oxidative stress response and its interrelationship to other stress defense systems. Altered autophagy phenotypes have been observed in lung diseases such as chronic obstructive lung disease, acute lung injury, cystic fibrosis, idiopathic pulmonary fibrosis, and pulmonary arterial hypertension, and asthma. Understanding the mechanisms by which ROS regulate autophagy will provide novel therapeutic targets for lung diseases. This review highlights our current understanding on the interplay between ROS and autophagy in the development of pulmonary disease.

Octreotide and lanreotide decrease ovarian ischemia-reperfusion injury in rats by improving oxidative and nitrosative stress

AIM

To investigate the protective effect of octreotide and lanreotide on ovarian damage in experimental ovarian ischemia-reperfusion injury.

METHODS

Fifty-six rats were separated into seven groups; group 1: sham group, group 2: surgical control group with 3-h torsion and detorsion, group 3: 0.02 mg/kg s.c. octreotide 30 min before 3-h torsion, group 4; octreotide just after detorsion for 7 days, group 5: octreotide 30 min before torsion and just after detorsion for 7 days, group 6: single time 20 mg/kg s.c. lanreotide before torsion, group 7: single time lanreotide just after detorsion.

RESULTS

All histopathological scores except congestion were significantly lower in group 1 than other groups. In addition, hemorrhage (group 2 vs 4: P < 0.05), degeneration (group 2 vs 4: P < 0.05, group 2 vs 5: P < 0.01 and group 2 vs 6: P < 0.05) and total damage score (group 2 vs 4: P < 0.05, group 2 vs 5: P < 0.05, group 2 vs 6: P < 0.05 and group 2 vs 7: P < 0.05) were significantly lower than other groups. Moreover, ovarian tissue total oxidant status and oxidative stress index levels were significantly decreased in groups 5 (both P < 0.05) and 7 (both P < 0.05) when compared to group 2. Furthermore, tissue levels of peroxynitrite were significantly higher in group 2 than groups 1, 3 and 5 (all P < 0.05).

CONCLUSIONS

Octreotide and lanreotide have a protective role against ischemia-reperfusion damage in rat torsion detorsion model by improving histopathological and biochemical findings including tissue levels of total oxidant status, oxidative stress index and peroxynitrite.

CRISPR/Cas9-mediated whole genomic wide knockout screening identifies mitochondrial ribosomal proteins involving in oxygen-glucose deprivation/reperfusion resistance

Recanalization therapy by intravenous thrombolysis or endovascular therapy is critical for the treatment of cerebral infarction. However, the recanalization treatment will also exacerbate acute brain injury and even severely threatens human life due to the reperfusion injury. So far, the underlying mechanisms for cerebral ischaemia-reperfusion injury are poorly understood and effective therapeutic interventions are yet to be discovered. Therefore, in the research, we subjected SK-N-BE(2) cells to oxygen-glucose deprivation/reperfusion (OGDR) insult and performed a pooled genome-wide CRISPR (clustered regularly interspaced short palindromic repeats)/Cas9 (CRISPR-associated protein 9) knockout screen to discover new potential therapeutic targets for cerebral ischaemia-reperfusion injury. We used Metascape to identify candidate genes which might involve in OGDR resistance. We found that the genes contributed to OGDR resistance were primarily involved in neutrophil degranulation, mitochondrial translation, and regulation of cysteine-type endopeptidase activity involved in apoptotic process and response to oxidative stress. We then knocked down some of the identified candidate genes individually. We demonstrated that MRPL19, MRPL32, MRPL52 and MRPL51 inhibition increased cell viability and attenuated OGDR-induced apoptosis. We also demonstrated that OGDR down-regulated the expression of MRPL19 and MRPL51 protein. Taken together, our data suggest that genome-scale screening with Cas9 is a reliable tool to analyse the cellular systems that respond to OGDR injury. MRPL19 and MRPL51 contribute to OGDR resistance and are supposed to be promising targets for the treatment of cerebral ischaemia-reperfusion damage.

Neuroprotective effect of cajaninstilbene acid against cerebral ischemia and reperfusion damages by activating AMPK/Nrf2 pathway

Introduction

Ischemic stroke is one of the leading causes of death worldwide. Recently, neuroprotection is regarded as an important preventative and therapeutic strategy for ischemic stroke. Cajaninstilbene acid (CSA), a unique stilbenoid with a styryl group, is a potential neuroprotective agent.

Objectives

Hence, this study aimed to evaluate the neuroprotective effect and molecular mechanism of CSA against cerebral ischemia/reperfusion (I/R) damages.

Methods

Cerebral ischemia was modeled by oxygen and glucose deprivation (OGD) in SH-SY5Y cells or transient intraluminal suture middle cerebral artery occlusion (MCAO) in rats, and tert-butyl hydroperoxide (t-BHP) was used to induce oxidative stress in SH-SY5Y cells. CSA (2.5, 5 mg/kg) was intraperitoneally given upon reperfusion after 2 h of MCAO. The signaling pathways were analyzed by Western blotting and inhibitor blocking.

Results

CSA possessed significant neuroprotective activity, as evidenced by the reduced cell death in OGD/R or t-BHP injured SH-SY5Y cells, and decreased infarct volume and neurological deficits in MCAO/R rats. Further studies indicated that the protective effect was achieved via the antioxidant activity of CSA, which decreased the oxidative stress and its related mitochondrial dysfunction in SH-SY5Y cells. Notably, Nrf2 was activated in SH-SY5Y cells and MCAO/R rats by CSA, and the inhibition of Nrf2 by brusatol weakened CSA-mediated neuroprotection. Furthermore, after applying a series of kinase inhibitors, CSA-induced Nrf2 activation was markedly inhibited by BML-275 (an AMPK inhibitor), implying that AMPK was the dominant kinase to regulate the Nrf2 pathway for CSA’s neuroprotective effects with enhanced AMPK phosphorylation observed both in vivo and in vitro.

Conclusion

CSA exerted neuroprotection via activating the AMPK/Nrf2 pathway to reduce I/R-induced cellular oxidative stress and mitochondrial disfunction. CSA could be a potential neuroprotective drug candidate for the treatment of ischemic stroke.

Flavonoids and Mitochondria: Activation of Cytoprotective Pathways?

A large number of diverse mechanisms that lead to cytoprotection have been described to date. Perhaps, not surprisingly, the role of mitochondria in these phenomena is notable. In addition to being metabolic centers, due to their role in cell catabolism, ATP synthesis, and biosynthesis these organelles are triggers and/or end-effectors of a large number of signaling pathways. Their role in the regulation of the intrinsic apoptotic pathway, calcium homeostasis, and reactive oxygen species signaling is well documented. In this review, we aim to characterize the prospects of influencing cytoprotective mitochondrial signaling routes by natural substances of plant origin, namely, flavonoids (e.g., flavanones, flavones, flavonols, flavan-3-ols, anthocyanidins, and isoflavones). Flavonoids are a family of widely distributed plant secondary metabolites known for their beneficial effects on human health and are widely applied in traditional medicine. Their pharmacological characteristics include antioxidative, anticarcinogenic, anti-inflammatory, antibacterial, and antidiabetic properties. Here, we focus on presenting mitochondria-mediated cytoprotection against various insults. Thus, the role of flavonoids as antioxidants and modulators of antioxidant cellular response, apoptosis, mitochondrial biogenesis, autophagy, and fission and fusion is reported. Finally, an emerging field of flavonoid-mediated changes in the activity of mitochondrial ion channels and their role in cytoprotection is outlined.

Naringin Targets NFKB1 to Alleviate Oxygen-Glucose Deprivation/Reoxygenation-Induced Injury in PC12 Cells Via Modulating HIF-1α/AKT/mTOR-Signaling Pathway

This study was designed to investigate the effect of naringin in oxygen-glucose deprivation/reoxygenation (OGD/R) model and its mechanism. The target gene of naringin and the enriched pathways of the gene were searched and identified using bioinformatics analysis. Then OGD/R model was built using PC12 cells, after which the cells were treated with different concentrations of naringin. Subsequently, cell proliferation and apoptosis were evaluated by cell counting kit-8 (CCK-8) and flow cytometry assays, respectively. Meanwhile, the expression of NFKB1 in PC12 cells underwent OGD/R-induced injury was detected by qRT-PCR, while apoptosis-related and pathway-related proteins were checked by Western blot. DCF-DA kit was utilized to measure the level of ROS. Our results revealed that NFKB1, which was upregulated in MACO rats and OGD/R-treated PC12 cells, was a target gene of naringin. Naringin could alleviate OGD/R-induced injury via promoting the proliferation, and repressing the apoptosis of PC12 cells through regulating the expression of NFKB1 and apoptosis-associated proteins and ROS level. Besides, the depletion of NFKB1 was positive to cell proliferation but negative to cell apoptosis. Moreover, the depletion of NFKB1 enhanced the influences of naringin on cell proliferation and apoptosis as well as the expression of apoptosis-related proteins and ROS level. Western blotting indicated that both naringin treatment and depletion of NFKB1 could increase the expression of HIF-1α, p-AKT, and p-mTOR compared with OGD/R group. What's more, treatment by naringin and si-NFKB1 together could significantly increase these effects. Nevertheless, the expression of AKT and mTOR among each group was almost not changed. In conclusion, naringin could prevent the OGD/R-induced injury in PC12 cells in vitro by targeting NFKB1 and regulating HIF-1α/AKT/mTOR-signaling pathway, which might provide novel ideas for the therapy of cerebral ischemia-reperfusion (I/R) injury.

Targeting Myeloperoxidase (MPO) Mediated Oxidative Stress and Inflammation for Reducing Brain Ischemia Injury: Potential Application of Natural Compounds

Oxidative stress and inflammation are two critical pathological processes of cerebral ischemia-reperfusion injury. Myeloperoxidase (MPO) is a critical inflammatory enzyme and therapeutic target triggering both oxidative stress and neuroinflammation in the pathological process of cerebral ischemia-reperfusion injury. MPO is presented in infiltrated neutrophils, activated microglial cells, neurons, and astrocytes in the ischemic brain. Activation of MPO can catalyze the reaction of chloride and H2O2 to produce HOCl. MPO also mediates oxidative stress by promoting the production of reactive oxygen species (ROS) and reactive nitrogen species (RNS), modulating the polarization and inflammation-related signaling pathways in microglia and neutrophils. MPO can be a therapeutic target for attenuating oxidative damage and neuroinflammation in ischemic stroke. Targeting MPO with inhibitors or gene deficiency significantly reduced brain infarction and improved neurological outcomes. This article discusses the important roles of MPO in mediating oxidative stress and neuroinflammation during cerebral ischemia-reperfusion injury and reviews the current understanding of the underlying mechanisms. Furthermore, we summarize the active compounds from medicinal herbs with potential as MPO inhibitors for anti-oxidative stress and anti-inflammation to attenuate cerebral ischemia-reperfusion injury, and as adjunct therapeutic agents for extending the window of thrombolytic treatment. We highlight that targeting MPO could be a promising strategy for alleviating ischemic brain injury, which merits further translational study.

Therapeutic targets of oxidative/nitrosative stress and neuroinflammation in ischemic stroke: Applications for natural product efficacy with omics and systemic biology

Oxidative/nitrosative stress and neuroinflammation are critical pathological processes in cerebral ischemia-reperfusion injury, and their intimate interactions mediate neuronal damage, blood-brain barrier (BBB) damage and hemorrhagic transformation (HT) during ischemic stroke. We review current progress towards understanding the interactions of oxidative/nitrosative stress and inflammatory responses in ischemic brain injury. The interactions between reactive oxygen species (ROS)/reactive nitrogen species (RNS) and innate immune receptors such as TLR2/4, NOD-like receptor, RAGE, and scavenger receptors are crucial pathological mechanisms that amplify brain damage during cerebral ischemic injury. Furthermore, we review the current progress of omics and systematic biology approaches for studying complex network regulations related to oxidative/nitrosative stress and inflammation in the pathology of ischemic stroke. Targeting oxidative/nitrosative stress and neuroinflammation could be a promising therapeutic strategy for ischemic stroke treatment. We then review recent advances in discovering compounds from medicinal herbs with the bioactivities of simultaneously regulating oxidative/nitrosative stress and pro-inflammatory molecules for minimizing ischemic brain injury. These compounds include sesamin, baicalin, salvianolic acid A, 6-paradol, silymarin, apocynin, 3H-1,2-Dithiole-3-thione, (-)-epicatechin, rutin, Dl-3-N-butylphthalide, and naringin. We finally summarize recent developments of the omics and systematic biology approaches for exploring the molecular mechanisms and active compounds of Traditional Chinese Medicine (TCM) formulae with the properties of antioxidant and anti-inflammation for neuroprotection. The comprehensive omics and systematic biology approaches provide powerful tools for exploring therapeutic principles of TCM formulae and developing precision medicine for stroke treatment.

Role of Mitophagy in Cardiovascular Disease

Cardiovascular disease is the leading cause of mortality worldwide, and mitochondrial dysfunction is the primary contributor to these disorders. Recent studies have elaborated on selective autophagy-mitophagy, which eliminates damaged and dysfunctional mitochondria, stabilizes mitochondrial structure and function, and maintains cell survival and growth. Numerous recent studies have reported that mitophagy plays an important role in the pathogenesis of various cardiovascular diseases. This review summarizes the mechanisms underlying mitophagy and advancements in studies on the role of mitophagy in cardiovascular disease.

Acteoside ameliorates experimental autoimmune encephalomyelitis through inhibiting peroxynitrite-mediated mitophagy activation

Multiple sclerosis (MS) is an inflammatory disease in central nervous system (CNS) with limited therapeutic drugs. In the present study, we explored the anti-inflammatory/neuroprotective properties of Acteoside (AC), an active compound from medicinal herb Radix Rehmanniae (RR), and neuroprotective effects of AC on MS pathology by using an experimental autoimmune encephalomyelitis (EAE) model. We tested the hypothesis that AC could alleviate EAE pathogenesis through inhibiting inflammation and ONOO^--mediated mitophagy activation in vivo and in vitro. The results showed that AC treatment effectively ameliorated neurological deficit score and postponed disease onset in the EAE mice. AC treatment inhibited inflammation/demyelination, alleviated peripheral activation and CNS infiltration of encephalitogenic CD4⁺ T cells and CD11b⁺ activated microglia/macrophages in the spinal cord of EAE mice. Meanwhile, AC treatment reduced ONOO^- production, down-regulated the expression of iNOS and NADPH oxidases, and inhibited neuronal apoptotic cell death and mitochondrial damage in the spinal cords of the EAE mice. Furthermore, AC treatment decreased the ratio of LC3-II to LC3-I in mitochondrial fraction, and inhibited the translocation of Drp1 to the mitochondria. In vitro studies further proved that AC possessed strong ONOO^- scavenging capability and protected the neuronal cells from nitrative cytotoxicity via suppressing ONOO^--mediated excessive mitophagy. Taken together, Acteoside could be a potential therapeutic agent for multiple sclerosis treatment. The suppression of ONOO^--induced excessive mitophagy activation could be one of the critical mechanisms contributing to its anti-inflammatory and anti-demyelinating properties.

Overexpression of transcription factor EB regulates mitochondrial autophagy to protect lipopolysaccharide-induced acute lung injury

BACKGROUND

Acute lung injury (ALI) is characterized by an acute inflammatory process, and oxidative stress in the lung tissue leads to a lack of effective therapeutics. This study aimed to identify whether the overexpression of transcription factor EB (TFEB) regulates mitophagy to protect against lipopolysaccharide (LPS)-induced ALI.

METHODS

We detected the expression of inflammatory factors, cytochrome c (Cyt.c) and nicotinamide adenine dinucleotide phosphate (NADPH), and autophagy-related proteins and observed the changes in lung histopathology induced by ALI in rats and the changes in the cell ultrastructure of primary alveolar type II epithelial cells induced by changing the expression of TFEB in the context of ALI.

RESULTS

The overexpression of TFEB could reduce the expression of proinflammatory factors, such as IL-1 and IL-6, and increase the expression of anti-inflammatory factors, such as IL-10, both in vitro and in vivo. In addition, the overexpression of TFEB could reduce the Cyt.c and NADPH levels both in vivo and in vitro. The overexpression of TFEB could upregulate the expression of autophagy-related proteins, such as lysosomal-associated membrane protein 1 (LAMP1), microtubule-associated protein light chain 3B (LC3B), and Beclin both in vivo and in vitro, and promote mitochondrial autophagy. The overexpression of TFEB significantly improved the histopathologic changes induced by LPS-induced ALI in rats. However, low TFEB expression produced the opposite results.

CONCLUSION

TFEB overexpression can decrease inflammation and mitochondrial damage in the lung tissue and alveolar epithelial cells through regulating mitochondrial autophagy to protect against LPS-induced ALI. Therefore, TFEB is likely a potential therapeutic target in LPS-induced ALI.

Therapeutic potential of naringin in neurological disorders

Neurological illnesses are multifactorial incurable debilitating disorders that may cause neurodegeneration. These diseases influence approximately 30 million people around the world. Despite several therapies, effective management of such disorders remains a global challenge. Thus, natural products might offer an alternative therapy for the treatment of various neurological disorders. Polyphenols, such as curcumin, resveratrol, myricetin, mangiferin and naringin (NRG) have been shown to possess promising potential in the treatment of neurogenerative illness. In this review, we have targeted the therapeutic potential of naringin as a neuroprotective agent. The overall neuroprotective effects and different possible underlying mechanisms related to NRG are discussed. In light of the strong evidence for the neuropharmacological efficacy of NRG in various experimental paradigms, it is concluded that this molecule should be further considered and studied as a potential candidate for neurotherapeutics, focusing on mechanistic and clinical trials to ascertain its efficacy.

Small-Molecule-Based Fluorescent Sensors for Selective Detection of Reactive Oxygen Species in Biological Systems

Reactive oxygen species (ROS) encompass a collection of intricately linked chemical entities characterized by individually distinct physicochemical properties and biological reactivities. Although excessive ROS generation is well known to underpin disease development, it has become increasingly evident that ROS also play central roles in redox regulation and normal physiology. A major challenge in uncovering the relevant biological mechanisms and deconvoluting the apparently paradoxical roles of distinct ROS in human health and disease lies in the selective and sensitive detection of these transient species in the complex biological milieu. Small-molecule-based fluorescent sensors enable molecular imaging of ROS with great spatial and temporal resolution and have thus been appreciated as excellent tools for aiding discoveries in modern redox biology. We review a selection of state-of-the-art sensors with demonstrated utility in biological systems. By providing a systematic overview based on underlying chemical sensing mechanisms, we wish to highlight the strengths and weaknesses in prior sensor works and propose some guiding principles for the development of future probes.

Realgar and cinnabar are essential components contributing to neuroprotection of Angong Niuhuang Wan with no hepatorenal toxicity in transient ischemic brain injury

Realgar and cinnabar are commonly used mineral medicine containing arsenic and mercury in Traditional Chinese Medicine (TCM). Angong Niuhuang Wan (AGNHW) is a representative realgar- and cinnabar-containing TCM formula for treating acute ischemic stroke, but its toxicology and neuropharmacological effects are not well addressed. In this study, we compared the neuropharmacological effects of AGNHW and modified AGNHW in an experimental ischemic stroke rat model. Male SD rats were subjected to 2 h of middle cerebral artery occlusion (MCAO) plus 22 h of reperfusion. Although oral administration of AGNHW for 7 days in the rats increased arsenic level in the blood and liver tissue, there were no significant changes in the arsenic level in kidney, mercury level in the blood, liver and kidney as well as hepatic and renal functions in MCAO rats. AGNHW revealed neuroprotective properties by reducing infarction volume, preserving blood-brain barrier integrity and improving neurological functions against cerebral ischemia-reperfusion injury. Interestingly, removing realgar and/or cinnabar from AGNHW abolished the neuroprotective effects. Meanwhile, AGNHW could scavenge peroxynitrite, down-regulate the expression of p47_phox, 3-NT and MMP-9 and up-regulate the expression of ZO-1 and claudin-5 in the ischemic brains, which were abolished by removing realgar and/or cinnabar from AGNHW. Notably, realgar or cinnabar had no neuroprotection when used alone. Taken together, oral administration of AGNHW for one week should be safe for treating ischemic stroke with neuroprotective effects. Realgar and cinnabar are necessary elements with synergetic actions with other herbal materials for the neuroprotective effects of AGNHW against cerebral ischemia-reperfusion injury.

Neuroprotective Effects and Hepatorenal Toxicity of Angong Niuhuang Wan Against Ischemia-Reperfusion Brain Injury in Rats

Angong Niuhuang Wan (AGNHW) is a classic prescription in traditional Chinese medicine (TCM) used for stroke treatment, but its efficacies remain to be confirmed. With its arsenic- and mercury-containing materials, the application of AGNHW raises great safety concerns. Herein, we aim to explore the neuropharmacological effects against cerebral ischemia-reperfusion injury and evaluate the toxicological effects of AGNHW for better use. Male SD rats were subjected to 2 h of middle cerebral artery occlusion (MCAO) and following 22 h of reperfusion. AGNHW (257 mg/kg, 1× AGNHW) were orally administered for pharmacological effects and 257, 514, and 1,028 mg/kg (equivalent to 1×, 2×, 4× AGNHW) were used for the toxicological study. The results revealed that AGNHW treatment reduced the infarct size and protected the blood-brain barrier (BBB) integrity in the MCAO rat ischemic stroke model. AGNHW treatment up-regulated bcl-2 expression and down-regulated the expressions of Bax, p47_phox, inducible nitric oxide synthase (iNOS), and 3-nitrotyrosine (3-NT), and inhibited the expressions and activities of matrix metalloproteinase-2 (MMP-2), MMP-9, and reserved tight junction protein zonula occludens-1 (ZO-1) and claudin-5 in the ischemic brains. These results indicated that the neuroprotective mechanisms of AGNHW could be associated with its antioxidant properties by inhibiting oxidative/nitrative stress-mediated MMP activation and protecting tight junction proteins in the ischemic brains. Administration of 1× AGNHW for 7 days would not induce the accumulation of mercury in blood, liver, and kidney at day 14. Administration of 2× AGNHW and 4× AGNHW for 7 days increased the level of mercury in the kidney. For arsenic level, administration of 1× AGNHW for 7 days would increase the level of arsenic in the liver and blood without increase of arsenic in the kidney at day 14. Administration of 2× AGNHW and 4× AGNHW for 7 days would further increase the level of arsenic in the liver and blood. There is no influence on body weight, organ index, histological structures, and renal and liver functions. These results suggest that short-term treatment of AGNHW within 1 week should be safe and has neuroprotective effects against cerebral ischemia-reperfusion injury.