Salidroside provides neuroprotection by modulating microglial polarization after cerebral ischemia

Mechanism of inflammatory response and therapeutic effects of stem cells in ischemic stroke: current evidence and future perspectives

Ischemic stroke is a leading cause of death and disability worldwide, with an increasing trend and tendency for onset at a younger age. China, in particular, bears a high burden of stroke cases. In recent years, the inflammatory response after stroke has become a research hotspot: understanding the role of inflammatory response in tissue damage and repair following ischemic stroke is an important direction for its treatment. This review summarizes several major cells involved in the inflammatory response following ischemic stroke, including microglia, neutrophils, monocytes, lymphocytes, and astrocytes. Additionally, we have also highlighted the recent progress in various treatments for ischemic stroke, particularly in the field of stem cell therapy. Overall, understanding the complex interactions between inflammation and ischemic stroke can provide valuable insights for developing treatment strategies and improving patient outcomes. Stem cell therapy may potentially become an important component of ischemic stroke treatment.

Salidroside improves blood-brain barrier integrity and cognitive function in hypobaric hypoxia mice by inhibiting microglia activation through GSK3β

Salidroside, an active component found in Rhodiola rosea L., has emerged as a potential therapeutic agent for the prevention and treatment of hypoxic brain injury, while the precise target and mechanism of salidroside were remain unclear. The study utilized techniques such as network pharmacology, transcriptome sequencing to investigate the mechanism and target of salidroside in regulating blood-brain barrier (BBB) function to protect hypoxic brain injury in vivo. Utilized macromolecular docking and molecular biology techniques to explore the molecular mechanism of salidroside in alleviating brain injury induced by hypoxia in BV2 cell model. The results show that salidroside alleviated the learning and memory dysfunction and pathological injury in mice exposed to hypobaric hypoxia, reduced brain water content and attenuate the inflammatory response and oxidative stress, effectively reversed S100β in serum and promoted the repair of BBB. GSK3β is an important therapeutic target of salidroside in the treatment of hypoxic cognitive impairment, and salidroside can specifically bind GSK3β in the ATP binding pocket, inducing the phosphorylation of GSK3β, targeting downstream Nrf-2 to regulate microglia activity, promoting the accumulation of β-catenin, thereby inhibiting microglial activation, improving the BBB integrity injury and achieving a neuroprotective effect. This study demonstrates that salidroside can inhibit the activation of microglia by inducing GSK3β phosphorylation, achieve neuroprotective effects and alleviate learning and memory dysfunction in hypobaric hypoxia mice. This study provides a theoretical basis for the development of salidroside and the clinical application of Rhodiola rosea L.

Epigenetic modifications of inflammation in spinal cord injury

Spinal cord injury (SCI) is a central nervous system injury that leads to neurological dysfunction or paralysis, which seriously affects patients' quality of life and causes a heavy social and economic burden. The pathological mechanism of SCI has not been fully revealed, resulting in unsatisfactory clinical treatment. Therefore, more research is urgently needed to reveal its precise pathological mechanism. Numerous studies have shown that inflammation is closely related to various pathological processes in SCI. Inflammatory response is an important pathological process leading to secondary injury, and sustained inflammatory response can exacerbate the injury and hinder the recovery of neurological function after injury. Epigenetic modification is considered to be an important regulatory mechanism in the pathological process of many diseases. Epigenetic modification mainly affects the function and characteristics of genes through the reversibility of mechanisms such as DNA methylation, histone modification, and regulation of non-coding RNA, thus having a significant impact on the pathological process of diseases and the survival state of the body. Recently, the role of epigenetic modification in the inflammatory response of SCI has gradually entered the field of view of researchers, and epigenetic modification may be a potential means to treat SCI. In this paper, we review the effects and mechanisms of different types of epigenetic modifications (including histone modifications, DNA methylation, and non-coding RNAs) on post-SCI inflammation and their potential therapeutic effects on inflammation to improve our understanding of the secondary SCI stage. This review aims to help identify new markers, signaling pathways and targeted drugs, and provide theoretical basis and new strategies for the diagnosis and treatment of SCI.

The effect of salidroside in promoting endogenous neural regeneration after cerebral ischemia/reperfusion involves notch signaling pathway and neurotrophic factors

BACKGROUND

Salidroside is the major bioactive and pharmacological active substance in Rhodiola rosea L. It has been reported to have neuroprotective effects on cerebral ischemia/reperfusion (I/R). However, whether salidroside can enhance neural regeneration after cerebral I/R is still unknown. This study investigated the effects of salidroside on the endogenous neural regeneration after cerebral I/R and the related mechanism.

METHODS

Focal cerebral I/R was induced in rats by transient middle cerebral artery occlusion/reperfusion (MCAO/R). The rats were intraperitoneally treated salidroside once daily for 7 consecutive days. Neurobehavioral assessments were performed at 3 days and 7 days after the injury. TTC staining was performed to assess cerebral infarct volume. To evaluate the survival of neurons, immunohistochemical staining of Neuronal Nuclei (NeuN) in the ischemic hemisphere were conducted. Also, immunofluorescence double or triple staining of the biomarkers of proliferating neural progenitor cells in Subventricular Zone (SVZ) and striatum of the ischemia hemisphere were performed to investigate the neurogenesis. Furthermore, reverse transcription-polymerase chain reaction (RT-PCR) and enzyme-linked immunosorbent assay (ELISA) were used to detect the expression of neurotrophic factors (NTFs) brain-derived neurotrophic factor (BDNF) and nerve growth factor (NGF). Expression of Notch1 and its target molecular Hes1 were also analyzed by western-blotting and RT-PCR.

RESULTS

Salidroside treatment ameliorated I/R induced neurobehavioral impairment, and reduced infarct volume. Salidroside also restored NeuN positive cells loss after I/R injury. Cerebral I/R injury significantly increased the expression of 5-Bromo-2'-Deoxyuridine (BrdU) and doublecotin (DCX), elevated the number of BrdU/Nestin/DCX triple-labeled cells in SVZ, and BrdU/Nestin/glial fibrillary acidic protein (GFAP) triple-labeled cells in striatum. Salidroside treatment further promoted the proliferation of BrdU/DCX labeled neuroblasts and BrdU/Nestin/GFAP labeled reactive astrocytes. Furthermore, salidroside elevated the mRNA expression and protein concentration of BDNF and NGF in ischemia periphery area, as well. Mechanistically, salidroside elevated Notch1/Hes1 mRNA expression in SVZ. The protein levels of them were also increased after salidroside administration.

CONCLUSIONS

Salidroside enhances the endogenous neural regeneration after cerebral I/R. The mechanism of the effect may involve the regulation of BDNF/NGF and Notch signaling pathway.

Exosomes from circRNA-Ptpn4 can modify ADSC treatment and repair nerve damage caused by cerebral infarction by shifting microglial M1/M2 polarization

Adipose-derived stem cells (ADSCs) have been demonstrated to improve the microenvironment after a stroke. Increasing studies have confirmed that hypoxia pretreatment of ADSCs resulted in a better therapeutic effect, but the mechanism of treatment is unclear. We isolated ADSCs and exosomes. Then, constructed a middle cerebral artery occlusion (MCAO) mice model. High-throughput sequencing was used to identify the differential expression of circRNA. Immunofluorescence and ELISAs were used to detect the therapeutic effects of ADSC exosomes on MCAO. The luciferase reporter assay was used to detect the interaction relationships among circRNA-Ptpn4, miR-153-3p, and Nrf2. This study showed that exosomes from hypoxia pretreatment of ADSCs had significant effects in promoting functional recovery following in vivo MCAO, through suppressed inflammatory factor expression, and shifting the microglial from M1 to M2 polarization activation. The results showed that circRNA-Ptpn4 was highly expressed during hypoxia pretreatment of ADSCs exosomes. Exosomes from circ-Ptpn4-modified ADSCs had a greater ability to promote functional recovery. The circ-Ptpn4 delivered from ADSC exosomes induced microglia/macrophage polarization from M1 to M2 by suppressing miR-153-3p and enhancing Nrf2 expressions. Taken together, the results showed that exosomes from circRNA-Ptpn4 modified ADSC treatment repaired nerve damage caused by cerebral infarction by inducing microglial M1/M2 polarization.

Therapeutic potential of salidroside in type I diabetic erectile dysfunction: Attenuation of oxidative stress and apoptosis via the Nrf2/HO-1 pathway

The primary objective of this work was to delve into the potential therapeutic advantages and dissect the molecular mechanisms of salidroside in enhancing erectile function in rats afflicted with diabetic microvascular erectile dysfunction (DMED), addressing both the whole-animal and cellular dimensions.We established a DMED model in Sprague‒Dawley (SD) rats and conducted in vivo experiments. The DMED rats were administered varying doses of salidroside, the effects of which on DMED were compared. Erectile function was evaluated by applying electrical stimulation to the cavernous nerves and measuring intracavernous pressure in real time. The penile tissue underwent histological examination and Western blotting. Hydrogen peroxide (H2O2) was employed in the in vitro trial to induce an oxidative stress for the purpose of identifying alterations in cell viability. The CCK-8 assay was used to measure the viability of corpus cavernous smooth muscle cells (CCSMCs) treated with vs. without salidroside. Flow cytometry was utilized to detect alterations in intracellular reactive oxygen species (ROS). Apoptosis was assessed through Western blotting and TdT-mediated dUTP nick-end labelling (TUNEL). Animal and cellular experiments indicate that the Nrf2/HO-1 signalling pathway may be upregulated by salidroside, leading to the improvement of erectile function in diabetic male rats by alleviating oxidative stress and reducing apoptosis in corpus cavernosum tissue.

Recent advances on signaling pathways and their inhibitors in spinal cord injury

Spinal cord injury (SCI) is a serious and disabling central nervous system injury. Its complex pathological mechanism can lead to sensory and motor dysfunction. It has been reported that signaling pathway plays a key role in the pathological process and neuronal recovery mechanism of SCI. Such as PI3K/Akt, MAPK, NF-κB, and Wnt/β-catenin signaling pathways. According to reports, various stimuli and cytokines activate these signaling pathways related to SCI pathology, thereby participating in the regulation of pathological processes such as inflammation response, cell apoptosis, oxidative stress, and glial scar formation after injury. Activation or inhibition of relevant pathways can delay inflammatory response, reduce neuronal apoptosis, prevent glial scar formation, improve the microenvironment after SCI, and promote neural function recovery. Based on the role of signaling pathways in SCI, they may be potential targets for the treatment of SCI. Therefore, understanding the signaling pathway and its inhibitors may be beneficial to the development of SCI therapeutic targets and new drugs. This paper mainly summarizes the pathophysiological process of SCI, the signaling pathways involved in SCI pathogenesis, and the potential role of specific inhibitors/activators in its treatment. In addition, this review also discusses the deficiencies and defects of signaling pathways in SCI research. It is hoped that this study can provide reference for future research on signaling pathways in the pathogenesis of SCI and provide theoretical basis for SCI biotherapy.

Salidroside directly activates HSC70, revealing a new role for HSC70 in BDNF signalling and neurogenesis after cerebral ischemia

Salidroside, a principal bioactive component of Rhodiola crenulata, is neuroprotective across a wide time window in stroke models. We investigated whether salidroside induced neurogenesis after cerebral ischemia and aimed to identify its primary molecular targets. Rats, subjected to transient 2 h of middle cerebral artery occlusion (MCAO), received intraperitoneal vehicle or salidroside ± intracerebroventricular HSC70 inhibitor VER155008 or TrkB inhibitor ANA-12 for up to 7 days. MRI, behavioural tests, immunofluorescent staining and western blotting measured effects of salidroside. Reverse virtual docking and enzymatic assays assessed interaction of salidroside with purified recombinant HSC70. Salidroside dose-dependently decreased cerebral infarct volumes and neurological deficits, with maximal effects by 50 mg/kg/day. This dose also improved performance in beam balance and Morris water maze tests. Salidroside significantly increased BrdU+/nestin+, BrdU+/DCX+, BrdU+/NeuN+, BrdU-/NeuN+ and BDNF+ cells in the peri-infarct cortex, with less effect in striatum and no significant effect in the subventricular zone. Salidroside was predicted to bind with HSC70. Salidroside dose-dependently increased HSC70 ATPase and HSC70-dependent luciferase activities, but it did not activate HSP70. HSC70 immunoreactivity concentrated in the peri-infarct cortex and was unchanged by salidroside. However, VER155008 prevented salidroside-dependent increases of neurogenesis, BrdU-/NeuN+ cells and BDNF+ cells in peri-infarct cortex. Salidroside also increased BDNF protein and p-TrkB/TrkB ratio in ischemic brain, changes prevented by VER155008 and ANA-12, respectively. Additionally, ANA-12 blocked salidroside-dependent neurogenesis and increased BrdU-/NeuN+ cells in the peri-infarct cortex. Salidroside directly activates HSC70, thereby stimulating neurogenesis and neuroprotection via BDNF/TrkB signalling after MCAO. Salidroside and similar activators of HSC70 might provide clinical therapies for ischemic stroke.

Efficient Biosynthesis of Salidroside via Artificial in Vivo enhanced UDP-Glucose System Using Cheap Sucrose as Substrate

Salidroside, a valuable phenylethanoid glycoside, is obtained from plants belonging to the Rhodiola genus, known for its diverse biological properties. At present, salidroside is still far from large-scale industrial production due to its lower titer and higher process cost. In this study, we have for the first time increased salidroside production by enhancing UDP-glucose supply in situ. We constructed an in vivo UDP-glucose regeneration system that works in conjunction with UDP-glucose transferase from Rhodiola innovatively to improve UDP-glucose availability. And a coculture was formed in order to enable de novo salidroside synthesis. Confronted with the influence of tyrosol on strain growth, an adaptive laboratory evolution strategy was implemented to enhance the strain's tolerance. Similarly, salidroside production was optimized through refinement of the fermentation medium, the inoculation ratio of the two microbes, and the inoculation size. The final salidroside titer reached 3.8 g/L. This was the highest titer achieved at the shake flask level in the existing reports. And this marked the first successful synthesis of salidroside in an in situ enhanced UDP-glucose system using sucrose. The cost was reduced by 93% due to the use of inexpensive substrates. This accomplishment laid a robust foundation for further investigations into the synthesis of other notable glycosides and natural compounds.

Extracellular vesicles released by transforming growth factor-beta 1-preconditional mesenchymal stem cells promote recovery in mice with spinal cord injury

Spinal cord injury (SCI) causes neuroinflammation, neuronal death, and severe axonal connections. Alleviating neuroinflammation, protecting residual cells and promoting neuronal regeneration via endogenous neural stem cells (eNSCs) represent potential strategies for SCI treatment. Extracellular vesicles (EVs) released by mesenchymal stem cells have emerged as pathological mediators and alternatives to cell-based therapies following SCI. In the present study, EVs isolated from untreated (control, C-EVs) and TGF-β1-treated (T-EVs) mesenchymal stem cells were injected into SCI mice to compare the therapeutic effects and explore the underlying mechanisms. Our study demonstrated for the first time that the application of T-EVs markedly enhanced the proliferation and antiapoptotic ability of NSCs in vitro. The infusion of T-EVs into SCI mice increased the shift from the M1 to M2 polarization of reactive microglia, alleviated neuroinflammation, and enhanced the neuroprotection of residual cells during the acute phase. Moreover, T-EVs increased the number of eNSCs around the epicenter. Consequently, T-EVs further promoted neurite outgrowth, increased axonal regrowth and remyelination, and facilitated locomotor recovery in the chronic stage. Furthermore, the use of T-EVs in Rictor-/- SCI mice (conditional knockout of Rictor in NSCs) showed that T-EVs failed to increase the activation of eNSCs and improve neurogenesis sufficiently, which suggested that T-EVs might induce the activation of eNSCs by targeting the mTORC2/Rictor pathway. Taken together, our findings indicate the prominent role of T-EVs in the treatment of SCI, and the therapeutic efficacy of T-EVs for SCI treatment might be optimized by enhancing the activation of eNSCs via the mTORC2/Rictor signaling pathway.

Salidroside promotes angiogenesis after cerebral ischemia in mice through Shh signaling pathway

AIMS

The purpose of this study was to explore the impacts of salidroside on vascular regeneration, vascular structural changes and long-term neurological recuperation following cerebral ischemia and its possible mechanism.

MAIN METHODS

From Day 1 to Day 28, young male mice with middle cerebral artery blockage received daily doses of salidroside and measured neurological deficits. On the 7th day after stroke, the volume of cerebral infarction was determined using TTC and HE staining. Microvascular density, astrocyte coverage, angiogenesis and the expression of the Shh signaling pathway were detected by IF, qRTPCR and WB at 7, 14 and 28 days after stroke. Changes in blood flow, blood vessel density and diameter from stroke to 28 days were measured by the LSCI and TPMI.

KEY FINDINGS

Compared with the dMACO group, the salidroside treatment group significantly promoted the recovery of neurological function. Salidroside was found to enhance cerebral blood flow perfusion and reduce the infarct on the 7th day after stroke. From the 7th to the 28th day after stroke, salidroside treatment boosted the expression of CD31, CD31+/BrdU+, and GFAP in the cortex around the infarction site. On the 14th day after stroke, salidroside significantly enhanced the width and density of blood vessels. Salidroside increased the expression of histones and genes in the Shh signaling pathway during treatment, and this effect was weakened by the Shh inhibitor Cyclopamine.

SIGNIFICANCE

Salidroside can restore nerve function, improve cerebral blood flow, reduce cerebral infarction volume, increase microvessel density and promote angiogenesis via the Shh signaling pathway.

A One-Stone-Two-Birds Strategy of Targeting Microbubbles with "Dual" Anti-Inflammatory and Blood-Brain Barrier "Switch" Function for Ischemic Stroke Treatment

Inflammation is considered to be the main target of the development of new stroke therapies. There are three key issues in the treatment of stroke inflammation: the first one is how to overcome the blood-brain barrier (BBB) to achieve drug delivery, the second one is how to select drugs to treat stroke inflammation, and the third one is how to achieve targeted drug delivery. In this study, we constructed hydrocortisone-phosphatidylserine microbubbles and combined them with ultrasound (US)-targeted microbubble destruction technology to successfully open the BBB to achieve targeted drug delivery. Phosphatidylserine on the microbubbles was used for its "eat me" effect to increase the targeting of the microvesicles. In addition, we found that hydrocortisone can accelerate the closure of the BBB, achieving efficient drug delivery while reducing the entry of peripheral toxins into the brain. In the treatment of stroke inflammation, it was found that hydrocortisone itself has anti-inflammatory effects and can also change the polarization of microglia from the harmful pro-inflammatory M1 phenotype to the beneficial anti-inflammatory M2 phenotype, thus achieving dual anti-inflammatory effects and enhancing the anti-inflammatory effects in ischemic areas after stroke, well reducing the cerebellar infarction volume by inhibiting the inflammatory response after cerebral ischemia. A confocal microendoscope was used to directly observe the polarization of microglial cells in living animal models for dynamic microscopic visualization detection showing the advantage of being closer to clinical work. Taken together, this study constructed a multifunctional targeted US contrast agent with the function of "one-stone-two-birds", which can not only "on-off" the BBB but also have "two" anti-inflammatory functions, providing a new strategy of integrated anti-inflammatory targeted delivery and imaging monitoring for ischemic stroke treatment.

Exploring Chinese herbal medicine for ischemic stroke: insights into microglia and signaling pathways

Ischemic stroke is a prevalent clinical condition affecting the central nervous system, characterized by a high mortality and disability rate. Its incidence is progressively rising, particularly among younger individuals, posing a significant threat to human well-being. The activation and polarization of microglia, leading to pro-inflammatory and anti-inflammatory responses, are widely recognized as pivotal factors in the pathogenesis of cerebral ischemia and reperfusion injury. Traditional Chinese herbal medicines (TCHMs) boasts a rich historical background, notable efficacy, and minimal adverse effects. It exerts its effects by modulating microglia activation and polarization, suppressing inflammatory responses, and ameliorating nerve injury through the mediation of microglia and various associated pathways (such as NF-κB signaling pathway, Toll-like signaling pathway, Notch signaling pathway, AMPK signaling pathway, MAPK signaling pathway, among others). Consequently, this article focuses on microglia as a therapeutic target, reviewing relevant pathway of literature on TCHMs to mitigate neuroinflammation and mediate IS injury, while also exploring research on drug delivery of TCHMs. The ultimate goal is to provide new insights that can contribute to the clinical management of IS using TCHMs.

Mechanisms of immune response and cell death in ischemic stroke and their regulation by natural compounds

Ischemic stroke (IS), which is the third foremost cause of disability and death worldwide, has inflammation and cell death as its main pathological features. IS can lead to neuronal cell death and release factors such as damage-related molecular patterns, stimulating the immune system to release inflammatory mediators, thereby resulting in inflammation and exacerbating brain damage. Currently, there are a limited number of treatment methods for IS, which is a fact necessitating the discovery of new treatment targets. For this review, current research on inflammation and cell death in ischemic stroke was summarized. The complex roles and pathways of the principal immune cells (microglia, astrocyte, neutrophils, T lymphocytes, and monocytes/macrophage) in the immune system after IS in inflammation are discussed. The mechanisms of immune cell interactions and the cytokines involved in these interactions are summarized. Moreover, the cell death mechanisms (pyroptosis, apoptosis, necroptosis, PANoptosis, and ferroptosis) and pathways after IS are explored. Finally, a summary is provided of the mechanism of action of natural pharmacological active ingredients in the treatment of IS. Despite significant recent progress in research on IS, there remain many challenges that need to be overcome.

Effect of salidroside on neuroprotection and psychiatric sequelae during the COVID-19 pandemic: A review

The coronavirus disease 2019 (COVID-19) pandemic has affected the mental health of individuals worldwide, and the risk of psychiatric sequelae and consequent mental disorders has increased among the general population, health care workers and patients with COVID-19. Achieving effective and widespread prevention of pandemic-related psychiatric sequelae to protect the mental health of the global population is a serious challenge. Salidroside, as a natural agent, has substantial pharmacological activity and health effects, exerts obvious neuroprotective effects, and may be effective in preventing and treating psychiatric sequelae and mental disorders resulting from stress stemming from the COVID-19 pandemic. Herein, we systematically summarise, analyse and discuss the therapeutic effects of salidroside in the prevention and treatment of psychiatric sequelae as well as its roles in preventing the progression of mental disorders, and fully clarify the potential of salidroside as a widely applicable agent for preventing mental disorders caused by stress; the mechanisms underlying the potential protective effects of salidroside are involved in the regulation of the oxidative stress, neuroinflammation, neural regeneration and cell apoptosis in the brain, the network homeostasis of neurotransmission, HPA axis and cholinergic system, and the improvement of synaptic plasticity. Notably, this review innovatively proposes that salidroside is a potential agent for treating stress-induced health issues during the COVID-19 pandemic and provides scientific evidence and a theoretical basis for the use of natural products to combat the current mental health crisis.

Betaine eliminates CFA-induced depressive-like behaviour in mice may be through inhibition of microglia and astrocyte activation and polarization

Chronic pain can induce not only nociceptive but also depressive emotions. A previous study demonstrated that betaine, a commonly used nutrient supplement, has an anti-nociceptive effect, but whether betaine can alleviate chronic pain-induced depressive emotion is elusive. Our current study found that betaine administration significantly eliminated complete Freund's adjuvant (CFA)-induced pain-related depressive-like behaviour. Mechanistically, betaine treatment inhibited microglia and astrocyte activation. Furthermore, betaine significantly promoted the transition of microglia from the M1 to the M2 phenotype, as well as the transition of astrocytes from the A1 to the A2 phenotype. Additionally, the release of pro-inflammatory factors such as IL-18, IL-1β and IL-6 and anti-inflammatory factors such as IL-10 in the hippocampus induced by CFA were also reversed by betaine administration. Overall, betaine has therapeutic effects on pain-related depressive-like phenotypes caused by CFA, possibly through altering the polarization of microglia and astrocytes to reduce neuroinflammation.

Development of dual-mode ELISA based on ALP-catalyzed APP hydrolysis for IL-6 detection

Sensitive and accurate detection of interleukin 6 (IL-6) is crucial for the early diagnosis of cerebral infarction to improve patient survival rates. However, the low-abundance of IL-6 in cerebral infarction presents a significant challenge in developing effective diagnosis method. Herein, we studied and analyzed the strong fluorescence property of 4-aminophenol phosphate (APP) and developed an enzyme-linked immunosorbent assay (ELISA) for IL-6 detection. The detection was based on the integration of optical signal change induced by alkaline phosphatase (ALP)-catalyzed APP hydrolysis and ALP-mediated ELISA. The generated colorimetric signal of 4-aminophenol, APP hydrolysis product, was used for ELISA of IL-6 with a detection limit of 0.1 ng/mL, and the visual detection of IL-6 was achieved. The changes in APP fluorescence have a good linear relationship with the logarithm of IL-6 concentration in the range of 0.005 ng/mL to 5.0 ng/mL, with a detection limit of 0.001 ng/mL, which was 100 times lower than that of conventional pNPP-based ELISA. Furthermore, the constructed ELISA effectively distinguished between samples from patients with cerebral infarction and volunteers with non-cerebral infarction, and the severity of symptoms was well distinguished based on IL-6 measurement. The dual-mode ELISA demonstrated high feasibility of low-abundance biomarker detection and displayed good potential for accurate in vitro diagnosis.

Salidroside ameliorated the pulmonary inflammation induced by cigarette smoke via mitigating M1 macrophage polarization by JNK/c-Jun

Pulmonary inflammation induced by cigarette smoke (CS) promoted the development of chronic obstructive pulmonary disease (COPD), and macrophage polarization caused by CS modulated inflammatory response. Previous studies indicated that salidroside exerted therapeutic effects in COPD, but the anti-inflammatory mechanisms were not clear. This study aimed to explore the effects and mechanisms of salidroside on macrophage polarization induced by CS. Wistar rats received passively CS exposure and were treated intraperitoneally with salidroside at a low, medium or high dose. Lung tissues were stained with hematoxylin-eosin. Emphysema and inflammatory scores were evaluated by histomorphology. Lung function, cytokines, and cell differential counts in BALF were detected. The macrophage polarization was determined by immunohistochemistry in lung tissues. Alveolar macrophages (AMs) were isolated and treated with cigarette smoke extract (CSE), salidroside or inhibitors of relative pathways. The polarization status was determined by qPCR, and the protein level was detected by Western blotting. CS exposure induced emphysema and lung function deterioration. The inflammatory scores, cytokines level and neutrophils counts were elevated after CS exposure. Salidroside treatment partly ameliorated above abnormal. CS exposure activated M1 and M2 polarization of AMs in vivo and in vitro, and salidroside mitigated M1 polarization induced by CS. CSE activated the JNK/c-Jun in AMs and the M1 polarization of AMs was inhibited by the inhibitors of JNK and AP-1. Salidroside treatment deactivated the JNK/c-Jun, which indicated that salidroside mitigated the M1 polarization of AMs induced by CS via inhibiting JNK/c-Jun. Salidroside treatment ameliorated the pulmonary inflammation and M1 polarization of AMs induced by CS, and the process might be mediated by the deactivation of JNK/c-Jun.

The NF-κB Pathway: a Focus on Inflammatory Responses in Spinal Cord Injury

Spinal cord injury (SCI) is a type of central nervous system trauma that can lead to severe nerve injury. Inflammatory reaction after injury is an important pathological process leading to secondary injury. Long-term stimulation of inflammation can further deteriorate the microenvironment of the injured site, leading to the deterioration of neural function. Understanding the signaling pathways that regulate responses after SCI, especially inflammatory responses, is critical for the development of new therapeutic targets and approaches. Nuclear transfer factor-κB (NF-κB) has long been recognized as a key factor in regulating inflammatory responses. The NF-κB pathway is closely related to the pathological process of SCI. Inhibition of this pathway can improve the inflammatory microenvironment and promote the recovery of neural function after SCI. Therefore, the NF-κB pathway may be a potential therapeutic target for SCI. This article reviews the mechanism of inflammatory response after SCI and the characteristics of NF-κB pathway, emphasizing the effect of inhibiting NF-κB on the inflammatory response of SCI to provide a theoretical basis for the biological treatment of SCI.

Network pharmacology analysis combined with experimental validation to explore the therapeutic mechanism of salidroside on intestine ischemia reperfusion

ETHNOPHARMACOLOGICAL RELEVANCE

Salidroside (SAL), a phenolic natural product present in Rhodiola rosea, are commonly used in the treatment of various ischemic-hypoxic diseases, including intestinal ischemia-reperfusion (IR) injury. However, their efficacy and potential mechanisms in the treatment of intestinal IR injury have not been investigated.

OBJECTIVE

The objective of the present study is to investigate the pharmacological mechanism of action of SAL on intestinal IR injury using a network pharmacology approach combined with experimental validation.

METHODS

In the present study, we used the Traditional Chinese Medicine Systematic Pharmacology (TCMSP) database and analysis platform and Comparative Toxicogenomics Database (CTD) to predict possible target genes of SAL, collected relevant target genes of intestinal IR injury from GeneCards and DisGenet websites, and collected summary data to screen common target genes. Then, the protein-protein interaction (PPI) target network was constructed and analyzed by STRING database and Cytoscape 3.8.2 with the above intersecting genes. Then, gene ontology (GO) and Kyoto Encyclopedia of Genes and Genomes (KEGG) pathway analyses were performed and the component-target-pathway network was constructed, followed by the use of molecular docking and molecular dynamic simulation to verify the possible binding conformation between SAL and candidate targets to further explore the potential targets of SAL in the treatment of intestinal IR injury. Finally, an in vivo model of mouse superior mesenteric artery ligation was established to assess the anti-intestinal IR injury effect of SAL by assessing histopathological changes in mouse small intestine by HE staining, detecting inflammatory factor expression by ELISA kit, and detecting the expression of key protein targets by Western blotting.

RESULTS

A total of 166 SAL target genes and 1740 disease-related targets were retrieved, and 88 overlapping proteins were obtained as potential therapeutic targets. The pathway enrichment analysis revealed that the pharmacological effects of SAL on intestinal IR injury were anti-hypoxic, anti-inflammatory and metabolic pathway related, and the molecular docking and molecular dynamic simulation results showed that the core bioactive components had good binding affinity for TXNIP and AMPK, and the immunoblotting results indicated that the expression levels of TXNIP and AMPK in the small intestinal tissues of mice in the drug-treated group compared with the model group were significantly changed.

CONCLUSION

SAL may target AMPK and TXNIP domains to act as a therapeutic agent for intestinal IR. These findings comprehensively reveal the potential therapeutic targets for SAL against intestinal IR and provide theoretical basis for the clinical application of SAL in the treatment of intestinal IR.

Salidroside ameliorates memory impairment following long-term ethanol intake in rats by modulating the altered intestinal microbiota content and hippocampal gene expression

Background

Salidroside (Sal), the main component of a famous herb Rhodiola rosea L, enhances memory performance and reduces fatigue. Therefore, this study assessed the effect of Sal on memory impairment induced by a long-term intake of ethanol (EtOH) in rats and investigated its relevant mechanisms using gut microbiota metagenomic analysis and hippocampal transcriptomic analysis.

Methods

Eighteen male SD rats were divided into the normal control group (CON group), EtOH model group (Model group), and Sal treatment group (Sal group). The rats in the Model and Sal groups intragastrically (i.g.) received 2 g/kg EtOH for 30 consecutive days, whereas the CON group was given an equal volume of distilled water. Meanwhile, the rats in the Sal group were administered i.g. 30 mg/kg Sal 60 min after EtOH intake. All rats were tested in the eight-arm maze for their memory function every 3 days. On the 30th day, metagenomic analyses of gut microbiota and transcriptomic analyses of the hippocampus were performed.

Results

Compared with the Model group, Sal treatment reduced the total time to complete the eight-arm maze task, decreased the number of arm entries, and abated the working memory error that was significant from the 9th day. Additionally, Sal intervention improved the gut microbiota composition, such as the increased abundance of Actinobacteria and Bifidobacterium, which was related to the metabolism of amino acids and terpenoid carbohydrate, endocrine function, and signal transduction by neurotransmitters. In the hippocampus, the EtOH intake differentially expressed 68 genes (54 genes increased, whereas 14 genes decreased), compared with the CON group, whereas Sal intervention affected these changes: 15 genes increased whereas 11 genes decreased. And, enrichment analyses revealed these genes were related to the structural components of the ribosome, mRNA splicing process, protein translation, mitochondria function, and immunological reaction. Finally, a correlation analysis found the memory impairment was positively correlated with the abnormal upregulation of Tomm7 but negatively correlated with decreased abundance of gut Alistipes_indistinctus, Lactobacillus_taiwanensis, Lactobacillus_paragasseri, and Lactobacillus johnsonii.

Conclusion

Sal improved memory impairment caused by long-term EtOH intake in rats, which may be related to its regulation of gut dysbiosis and hippocampal dysfunction.

Transcriptome Profiling of Hippocampus After Cerebral Hypoperfusion in Mice

Chronic cerebral hypoperfusion (CCH) is considered to be one of the major mechanism in the pathogenesis of vascular cognitive impairment (VCI). Increased inflammatory cells, particularly microglia, often parallel hypoperfusion-induced gray matter damage such as hippocampal lesions, but the exact mechanism remains largely unknown. To understand the pathological mechanisms, we analyzed hippocampus-specific transcriptome profiles after cerebral hypoperfusion. The mouse hypoperfusion model was induced by employing the 0.16/0.18 mm bilateral common carotid artery stenosis (BCAS) procedure. Cerebral blood flow (CBF) was assessed after 3-week hypoperfusion. Pathological changes were evaluated via hematoxylin staining and immunofluorescence staining. RNA-sequencing (RNA-seq) was performed using RNA samples of sham- or BCAS-operated mice, followed by quantitative real-time PCR (qRT-PCR) validation. We found that the 0.16/0.18 mm BCAS induced decreased CBF, hippocampal neuronal loss, and microglial activation. Furthermore, GSEA between sham and BCAS mice showed activation of interferon-beta signaling along with inflammatory immune responses. In addition, integrative analysis with published single-cell RNA-seq revealed that up-regulated differentially expressed genes (DEGs) were enriched in a distinct cell type of "microglia," and down-regulated DEGs were enriched in "CA1 pyramidal," not in "interneurons" or "S1 pyramidal." This database of transcriptomic profiles of BCAS-hypoperfusion will be useful for future studies to explore potential targets for vascular cognitive dysfunction.

Salidroside alleviates cognitive impairment by inhibiting ferroptosis via activation of the Nrf2/GPX4 axis in SAMP8 mice

BACKGROUND

Alzheimer's disease (AD) is a neurogenerative disease and remains no effective method for stopping its progress. Ferroptosis and adaptive immunity have been proven to contribute to AD pathogenesis. Salidroside exhibits neuroprotective and immunomodulatory effects. However, the underlying mechanisms linking salidroside, ferroptosis, and adaptive immunity in AD remain uncertain.

PURPOSE

The objective of this study is to explore the neuroprotective effects and the potential molecular mechanisms of salidroside against neuronal ferroptosis and CD8⁺ T cell infiltration in senescence-accelerated mouse prone 8 (SAMP8) mice.

STUDY DESIGN AND METHODS

SAMP8 mice were employed as an AD model and were treated with salidroside for 12 weeks. Behavioral tests, immunohistochemistry, HE and Nissl staining, immunofluorescence, transmission electron microscopy, quantitative proteomics, bioinformatic analysis, flow cytometry, iron staining, western blotting, and molecular docking were performed.

RESULTS

Treatment with salidroside dose-dependently attenuated cognitive impairment, reduced the accumulation of Aβ plaques and restored neuronal damage. Salidroside also suppressed the infiltration of CD8⁺T cells, oxidative stress, and inflammatory cytokines, and improved mitochondrial metabolism, iron metabolism, lipid metabolism, and redox in the SAMP8 mice brain. The administration of salidroside decreased iron deposition, reduced TFR1, and ACSL4 protein expression, upregulated SLC7A11, and GPX4 protein expression, and promoted the Nrf2/GPX4 axis activation.

CONCLUSION

In conclusion, neuronal ferroptosis and CD8⁺T cells are involved in the process of cognitive impairment in SAMP8 mice. Salidroside alleviates cognitive impairment and inhibits neuronal ferroptosis. The underlying mechanisms may involve the Nrf2/GPX4 axis activation and reduction in CD8⁺T cells infiltration. This study provides some evidence for the roles of salidroside in adaptive immunity and neuronal ferroptosis in SAMP8 mice.

Salidroside pretreatment alleviates PM2.5 caused lung injury via inhibition of apoptosis and pyroptosis through regulating NLRP3 Inflammasome

Ambient fine particulate matter (PM_2.5) is considered a leading cause of pathogenic particulate matter induced lung injury. And Salidroside (Sal), the major bioactive constituent isolated from Rhodiola rosea L., has been shown to ameliorate lung injury in various conditions. To uncover the possible therapy for PM_2.5 related pulmonary disease, we evaluated the protective role of Sal pre-treatment on PM_2.5 induced lung injury in mice by utilizing the survival analysis, hematoxylin and eosin (H&E) staining, lung injury score, lung wet-to-dry weight ratio, enzyme-linked immunosorbent assay (ELISA) kits, immunoblot, immunofluorescence, and transmission electron microscopy (TEM). Impressively, our findings strongly indicated Sal as an effective precaution against PM_2.5 induced lung injury. Pre-administration of Sal before PM_2.5 treatment reduced the mortality within 120 h and alleviated inflammatory responses by reducing the release of proinflammatory cytokines, including TNF-α, IL-1β, and IL-18. Meanwhile, Sal pretreatment blocked apoptosis and pyroptosis that introduced the tissue damage under PM_2.5 treatment via regulating Bax/Bcl-2/caspase-3 and NF-κB/NLRP3/caspase-1 signal pathways. In summary, our research demonstrated that Sal could be a potential preventative therapy for PM_2.5 caused lung injury by inhibiting the initiation and development of apoptosis and pyroptosis through down-regulating NLRP3 inflammasome pathway.

A novel extract from Ginkgo biloba inhibits neuroinflammation and maintains white matter integrity in experimental stroke

Ginkgo biloba L. leaf extract (GBE) has been added in many commercial herbal formulations such as EGb 761 and Shuxuening Injection to treat cardiovascular diseases and stroke worldwide. However, the comprehensive effects of GBE on cerebral ischemia remained unclear. Using a novel GBE (nGBE), which consists of all the compounds of traditional (t)GBE and one new compound, pinitol, we investigated its effect on inflammation, white matter integrity, and long-term neurological function in an experimental stroke model. Both transient middle cerebral artery occlusion (MCAO) and distal MCAO were conducted in male C57/BL6 mice. We found that nGBE significantly reduced infarct volume at 1, 3, and 14 days after ischemia. Sensorimotor and cognitive functions were superior in nGBE treated mice after MCAO. nGBE inhibited the release of IL-1β in the brain, promoted microglial ramification, and regulated the microglial M1 to M2 phenotype shift at 7 days post injury. In vitro analyses showed that nGBE treatment reduced the production of IL-1β and TNFα in primary microglia. Administration of nGBE also decreased the SMI-32/MBP ratio and enhanced myelin integrity, thus exhibiting improved white matter integrity at 28 days post stroke. These findings demonstrate that nGBE protects against cerebral ischemia by inhibiting microglia-related inflammation and promoting white matter repair, suggesting that nGBE is a promising therapeutic strategy for long-term recovery after stroke.

Regulatory mechanisms of natural compounds from traditional Chinese herbal medicines on the microglial response in ischemic stroke

BACKGROUND

Development of clinically effective neuroprotective agents for stroke therapy is still a challenging task. Microglia play a critical role in brain injury and recovery after ischemic stroke. Traditional Chinese herbal medicines (TCHMs) are based on a unique therapeutic principle, have various formulas, and have long been widely used to treat stroke. Therefore, the active compounds in TCHMs and their underlying mechanisms of action are attracting increasing attention in the field of stroke drug development.

PURPOSE

To summarize the regulatory mechanisms of TCHM-derived natural compounds on the microglial response in animal models of ischemic stroke.

METHODS

We searched studies published until 10 April 2023 in the Web of Science, PubMed, and ScienceDirect using the following keywords: natural compounds, natural products or phytochemicals, traditional Chinese Medicine or Chinese herbal medicine, microglia, and ischemic stroke. This review was prepared according to PRISMA (Preferred Reporting Item for Systematic Reviews and Meta-Analysis) guidelines.

RESULTS

Natural compounds derived from TCHMs can attenuate the M1 phenotype of microglia, which is involved in the detrimental inflammatory response, via inhibition of NF-κB, MAPKs, JAK/STAT, Notch, TLR4, P2X7R, CX3CR1, IL-17RA, the NLRP3 inflammasome, and pro-oxidant enzymes. Additionally, the neuroprotective response of microglia with the M2 phenotype can be enhanced by activating Nrf2/HO-1, PI3K/AKT, AMPK, PPARγ, SIRT1, CB2R, TREM2, nAChR, and IL-33/ST2. Several clinical trials showed that TCHM-derived natural compounds that regulate microglial responses have significant and safe therapeutic effects, but further well-designed clinical studies are needed.

CONCLUSIONS

Further research regarding the direct targets and potential pleiotropic or synergistic effects of natural compounds would provide a more reasonable approach for regulation of the microglial response with the possibility of successful stroke drug development.

Oleoylethanolamide Protects against Acute Ischemic Stroke by Promoting PPARα-Mediated Microglia/Macrophage M2 Polarization

Oleoylethanolamide (OEA) has been demonstrated to be a feasible protectant in ischemic stroke. However, the mechanism for OEA-afforded neuroprotection remains elusive. The present study aimed to investigate the neuroprotective effects of OEA on peroxisome proliferator-activated receptor α (PPARα)-mediated microglia M2 polarization after cerebral ischemia. Transient middle cerebral artery occlusion (tMCAO) was induced for 1 h in wild-type (WT) or PPARα-knock-out (KO) mice. Mouse small glioma cells (BV2) microglia and primary microglia cultures were used to evaluate the direct effect of OEA on microglia. A coculture system was used to further elucidate the effect of OEA on microglial polarization and ischemic neurons' fate. OEA promoted the microglia switch from an inflammatory M1 phenotype to the protective M2 phenotype and enhanced the binding of PPARα with the arginase1 (Arg1) and Ym1 promoter in WT mice but not in KO mice after MCAO. Notably, the increased M2 microglia caused by OEA treatment were strongly linked to neuron survival after ischemic stroke. In vitro studies confirmed that OEA shifted BV2 microglia from (lipopolysaccharide) LPS-induced M1-like to M2-like phenotype through PPARα. Additionally, the activation of PPARα in primary microglia by OEA led to an M2 protective phenotype that enhanced neuronal survival against oxygen-glucose deprivation (OGD) in the coculture systems. Our findings demonstrate the novel effects of OEA in enhancing microglia M2 polarization to protect neighboring neurons by activating the PPARα signal, which is a new mechanism of OEA against cerebral ischemic injury. Therefore, OEA might be a promising therapeutic drug for stroke and targeting PPARα-mediated M2 microglia may represent a new strategy to treat ischemic stroke.

The Therapeutic Potential of Salidroside for Parkinson's Disease

Parkinson's disease (PD), a neurological disorder, is characterized by the progressive loss of dopaminergic (DA) neurons in the substantia nigra. Its incidence increases with age. Salidroside, a phenolic compound extracted from Sedum roseum, reportedly has multiple biological and pharmacological activities in the nervous system. However, its effects on PD remain unclear. In this review, we summarize the effects of salidroside on PD with regard to DA metabolism, neuronal protection, and glial activation. In addition, we summarize the susceptibility genes and their underlying mechanisms related to antioxidation, inflammation, and autophagy by regulating mitochondrial function, ubiquitin, and multiple signaling pathways involving NF-κB, mTOR, and PI3K/Akt. Although recent studies were based on animal and cellular experiments, this review provides evidence for further clinical utilization of salidroside for PD.

The Implications of Microglial Regulation in Neuroplasticity-Dependent Stroke Recovery

Stroke causes varying degrees of neurological deficits, leading to corresponding dysfunctions. There are different therapeutic principles for each stage of pathological development. Neuroprotection is the main treatment in the acute phase, and functional recovery becomes primary in the subacute and chronic phases. Neuroplasticity is considered the basis of functional restoration and neurological rehabilitation after stroke, including the remodeling of dendrites and dendritic spines, axonal sprouting, myelin regeneration, synapse shaping, and neurogenesis. Spatiotemporal development affects the spontaneous rewiring of neural circuits and brain networks. Microglia are resident immune cells in the brain that contribute to homeostasis under physiological conditions. Microglia are activated immediately after stroke, and phenotypic polarization changes and phagocytic function are crucial for regulating focal and global brain inflammation and neurological recovery. We have previously shown that the development of neuroplasticity is spatiotemporally consistent with microglial activation, suggesting that microglia may have a profound impact on neuroplasticity after stroke and may be a key therapeutic target for post-stroke rehabilitation. In this review, we explore the impact of neuroplasticity on post-stroke restoration as well as the functions and mechanisms of microglial activation, polarization, and phagocytosis. This is followed by a summary of microglia-targeted rehabilitative interventions that influence neuroplasticity and promote stroke recovery.

Possible Implications of Obesity-Primed Microglia that Could Contribute to Stroke-Associated Damage

Microglia, the resident macrophages of the central nervous system, are essential players during physiological and pathological processes. Although they participate in synaptic pruning and maintenance of neuronal circuits, microglia are mainly studied by their activity modulating inflammatory environment and adapting their phenotype and mechanisms to insults detected in the brain parenchyma. Changes in microglial phenotypes are reflected in their morphology, membrane markers, and secreted substances, stimulating neighbor glia and leading their responses to control stimuli. Understanding how microglia react in various microenvironments, such as chronic inflammation, made it possible to establish therapeutic windows and identify synergic interactions with acute damage events like stroke. Obesity is a low-grade chronic inflammatory state that gradually affects the central nervous system, promoting neuroinflammation development. Obese patients have the worst prognosis when they suffer a cerebral infarction due to basal neuroinflammation, then obesity-induced neuroinflammation could promote the priming of microglial cells and favor its neurotoxic response, potentially worsening patients' prognosis. This review discusses the main microglia findings in the obesity context during the course and resolution of cerebral infarction, involving the temporality of the phenotype changes and balance of pro- and anti-inflammatory responses, which is lost in the swollen brain of an obese subject. Obesity enhances proinflammatory responses during a stroke. Obesity-induced systemic inflammation promotes microglial M₁ polarization and priming, which enhances stroke-associated damage, increasing M₁ and decreasing M₂ responses.

Cortex-specific transcriptome profiling reveals upregulation of interferon-regulated genes after deeper cerebral hypoperfusion in mice

Background: Chronic cerebral hypoperfusion (CCH) is commonly accompanied by brain injury and glial activation. In addition to white matter lesions, the intensity of CCH greatly affects the degree of gray matter damage. However, little is understood about the underlying molecular mechanisms related to cortical lesions and glial activation following hypoperfusion. Efforts to investigate the relationship between neuropathological alternations and gene expression changes support a role for identifying novel molecular pathways by transcriptomic mechanisms.

Methods: Chronic cerebral ischemic injury model was induced by the bilateral carotid artery stenosis (BCAS) using 0.16/0.18 mm microcoils. Cerebral blood flow (CBF) was evaluated using laser speckle contrast imaging (LSCI) system. Spatial learning and memory were assessed by Morris water maze test. Histological changes were evaluated by Hematoxylin staining. Microglial activation and neuronal loss were further examined by immunofluorescence staining. Cortex-specific gene expression profiling analysis was performed in sham and BCAS mice, and then validated by quantitative RT-PCR and immunohistochemistry (IHC).

Results: In our study, compared with the sham group, the right hemisphere CBF of BCAS mice decreased to 69% and the cognitive function became impaired at 4 weeks postoperation. Besides, the BCAS mice displayed profound gray matter damage, including atrophy and thinning of the cortex, accompanied by neuronal loss and increased activated microglia. Gene set enrichment analysis (GSEA) revealed that hypoperfusion-induced upregulated genes were significantly enriched in the pathways of interferon (IFN)-regulated signaling along with neuroinflammation signaling. Ingenuity pathway analysis (IPA) predicted the importance of type I IFN signaling in regulating the CCH gene network. The obtained RNA-seq data were validated by qRT-PCR in cerebral cortex, showing consistency with the RNA-seq results. Also, IHC staining revealed elevated expression of IFN-inducible protein in cerebral cortex following BCAS-hypoperfusion.

Conclusion: Overall, the activation of IFN-mediated signaling enhanced our understanding of the neuroimmune responses induced by CCH. The upregulation of IFN-regulated genes (IRGs) might exert a critical impact on the progression of cerebral hypoperfusion. Our improved understanding of cortex-specific transcriptional profiles will be helpful to explore potential targets for CCH.

Salidroside alleviates ulcerative colitis via inhibiting macrophage pyroptosis and repairing the dysbacteriosis-associated Th17/Treg imbalance

Ulcerative colitis (UC) is a chronic inflammatory bowel disease characterized by flora disequilibrium and mucosal immunity disorder. Here, we report that salidroside effectively restricts experimental colitis from two aspects of intestinal macrophage pyroptosis and dysbacteriosis-derived colonic Th17/Treg imbalance. In innate immunity, the upregulated TREM1 and pyroptosis-related proteins in inflamed colons were inhibited by salidroside administration and further experiments in vitro showed that salidroside suppressed LPS/ATP-induced bone marrow-derived macrophages (BMDMs) pyroptosis evident by the decline of LDH and IL-1β release as well as the protein level of NLRP3, caspase-1, and GSDMD p30. Moreover, the TREM1 inhibitor weakened the effect of salidroside on BMDMs pyroptosis, whereas salidroside still could downregulate TREM1 when NLRP3 was inhibited. In adaptive immunity, salidroside improved the gut microflora diversity and Th17/Treg ratio in DSS-induced mice, especially promoting the abundance of Firmicutes. Clearance of the gut flora blocked the benefit of salidroside on colonic inflammation and Th17/Treg adaptive immunity, but transplanting salidroside-treated foecal bacterium into flora-depleted wild mice reproduced the resistance of salidroside to gut inflammation. Taken together, our data demonstrated that salidroside protected experimental colitis via skewing macrophage pyroptosis and Th17/Treg balance, indicating its potential effect on UC and other immune disorders.

Autophagy in glaucoma pathogenesis: Therapeutic potential and future perspectives

Glaucoma is a common blinding eye disease characterized by progressive loss of retinal ganglion cells (RGCs) and their axons, progressive loss of visual field, and optic nerve atrophy. Autophagy plays a pivotal role in the pathophysiology of glaucoma and is closely related to its pathogenesis. Targeting autophagy and blocking the apoptosis of RGCs provides emerging guidance for the treatment of glaucoma. Here, we provide a systematic review of the mechanisms and targets of interventions related to autophagy in glaucoma and discuss the outlook of emerging ideas, techniques, and multidisciplinary combinations to provide a new basis for further research and the prevention of glaucomatous visual impairment.

Betaine Inhibits NLRP3 Inflammasome Hyperactivation and Regulates Microglial M1/M2 Phenotypic Differentiation, Thereby Attenuating Lipopolysaccharide-Induced Depression-Like Behavior

Depression is one of the most important mental illnesses and is closely related to inflammation. Betaine is a natural product with an anti-inflammatory and antioxidant activities. However, the mechanism by which betaine ameliorates depression-like behaviors induced by lipopolysaccharide (LPS) is poorly understood. The purpose of this study was to investigate the neuroprotective effect of betaine on LPS-induced depression-like behavior in mice and its mechanism of action. ICR mice were randomly divided into four groups: the control group, the LPS model group (0.83 mg/kg), the positive drug group (MIDO, 50 mg/kg), and the betaine group (5% and 1% in drinking water). The betaine group was administered for 21 days, and on the 22nd day, except for the blank group, LPS (0.83 mg/kg) was intraperitoneally injected to establish a lipopolysaccharide-induced mice depression-like model. Twenty-four hours after LPS injection, the tail suspension test (TST), open field test (OFT), and sucrose preference test (SPT) were performed to evaluate the effect of betaine on LPS-induced depressive behavior in mice. After the behavioral study, the mouse brain, hippocampus, and serum were taken for detection. The expressions of cytokines and inflammatory mediators were detected by ELISA, HE staining, immunofluorescence, immunohistochemistry, and western blotting. Western blotting was used to detect the protein expression levels of the nucleotide-binding oligomerization domain-like receptor protein 3 (NLRP3), caspase-1, and ASC, the protein expression levels of the microglial polarization markers COX-2, inducible nitric oxide synthase (iNOS), and CD206. The results showed that betaine significantly ameliorated the depression-like behavior in LPS-induced mice, significantly attenuated the production of proinflammatory cytokines and increased the release of an anti-inflammatory cytokines. Betaine decreased the expression of the NLRP3 inflammasome, decreased the expression of M1 polarization markers, tumor necrosis factor-alpha (TNF-α), interleukin-1β (IL-1β), COX-2, and iNOS and promoted the expression of M2 polarization marker CD206. Our study suggests that betaine may promote the transition of microglia from the M1 to the M2 phenotype by inhibiting NLRP3 inflammasome activation, thereby attenuating lipopolysaccharide-induced depression-like behavior.

The mechanism of ferroptosis regulating oxidative stress in ischemic stroke and the regulation mechanism of natural pharmacological active components

Cerebrovascular diseases, such as ischemic stroke, pose serious medical challenges worldwide due to their high morbidity and mortality and limitations in clinical treatment strategies. Studies have shown that reactive oxygen species (ROS)-mediated inflammation, excitotoxicity, and programmed cell death of each neurovascular unit during post-stroke hypoxia and reperfusion play an important role in the pathological cascade. Ferroptosis, a programmed cell death characterized by iron-regulated accumulation of lipid peroxidation, is caused by abnormal metabolism of lipids, glutathione (GSH), and iron, and can accelerate acute central nervous system injury. Recent studies have gradually uncovered the pathological process of ferroptosis in the neurovascular unit of acute stroke. Some drugs such as iron chelators, ferrostatin-1 (Fer-1) and liproxstatin-1 (Lip-1) can protect nerves after neurovascular unit injury in acute stroke by inhibiting ferroptosis. In addition, combined with our previous studies on ferroptosis mediated by natural compounds in ischemic stroke, this review summarized the progress in the regulation mechanism of natural chemical components and herbal chemical components on ferroptosis in recent years, in order to provide reference information for future research on ferroptosis and lead compounds for the development of ferroptosis inhibitors.

Chuanzhitongluo regulates microglia polarization and inflammatory response in acute ischemic stroke

BACKGROUND AND PURPOSE

Chuanzhitongluo (CZTL), a traditional Chinese medicine mixture, is used in the recovery period of acute ischemic stroke (AIS), and effectively improves the prognosis of AIS patients. This study aims to evaluate whether CZTL regulates microglia polarization and inflammatory response to reduce brain damage in the acute phase of AIS.

METHODS

A mouse model of AIS was prepared by the photochemical method. Cerebral infarct volume was detected by 2,3,5-Triphenyltetrazolium chloride (TTC) staining. Terminal deoxynucleotidyl transferase dUTP nick end labeling (TUNEL) assay was used to assess neuronal apoptosis. Gene expression profile change was explored by Gene chip. Inflammatory factors were analyzed by Protein microarray. The Immunofluorescence double-labeling assay was executed to elucidate the effects of CD16⁺ / Iba-1⁺ and CD206⁺ / Iba-1⁺ in the peripheral area of cerebral ischemia.

RESULTS

Results revealed that CZTL treatment alleviated the neurological impairment, reduced cerebral infarct volume, and inhibited neuronal apoptosis. CZTL altered gene expression profiles, which indicate that CZTL may be involved in regulating neuroinflammation. CZTL restrained inflammatory responses by down-regulated pro-inflammatory cytokines expression and enhanced anti-inflammatory cytokines level. Further experiments demonstrated that CZTL inhibited the activation of NLRP3 inflammasome, which decreasing the inflammatory response. In addition, CZTL promoted the transformation of microglia from M1 to M2 phenotype.

CONCLUSIONS

These results indicate that CZTL alleviates neuroinflammation and brain damage after AIS in mice, which may be mediated by modulating microglia polarization.

Microglial phagocytosis and regulatory mechanisms after stroke

Stroke, including ischemic stroke and hemorrhagic stroke can cause massive neuronal death and disruption of brain structure, which is followed by secondary inflammatory injury initiated by pro-inflammatory molecules and cellular debris. Phagocytic clearance of cellular debris by microglia, the brain's scavenger cells, is pivotal for neuroinflammation resolution and neurorestoration. However, microglia can also exacerbate neuronal loss by phagocytosing stressed-but-viable neurons in the penumbra, thereby expanding the injury area and hindering neurofunctional recovery. Microglia constantly patrol the central nervous system using their processes to scour the cellular environment and start or cease the phagocytosis progress depending on the "eat me" or "don't eat me'' signals on cellular surface. An optimal immune response requires a delicate balance between different phenotypic states to regulate neuro-inflammation and facilitate reconstruction after stroke. Here, we examine the literature and discuss the molecular mechanisms and cellular pathways regulating microglial phagocytosis, their resulting effects in brain injury and neural regeneration, as well as the potential therapeutic targets that might modulate microglial phagocytic activity to improve neurological function after stroke.

Salidroside Regulates Mitochondrial Homeostasis After Polarization of RAW264.7 Macrophages

ABSTRACT

Salidroside has anti-inflammatory and antiatherosclerotic effects, and mitochondrial homeostasis imbalance is closely related to cardiovascular disease. The aim of this study was to investigate the effect of salidroside on mitochondrial homeostasis after macrophage polarization and elucidate its possible mechanism against atherosclerosis. RAW264.7 cells were stimulated with 1 μg·mL -1 Lipopolysaccharide and 50 ng·mL -1 IFN-γ establish M1 polarization and were also pretreated with 400 μM salidroside. The relative expression of proinflammatory genes was detected by RT-PCR whereas that of mitochondrial homeostasis-related proteins and nuclear factor kappa-B (NF-κB) was detected by WB. Levels of intracellular reactive oxygen species (ROS), mitochondrial membrane potential, and mass were measured by chemifluorescence whereas that of NF-κB nuclear translocation was detected by immunofluorescence. Compared with the Mφ group, the M1 group demonstrated increased mRNA expression of interleukin-1β , inductible nitric oxide synthase (iNOS), and tumor necrosis factor-α ; increased protein expression of iNOS, NOD-like receptor protein 3, putative kinase 1 , and NF-κB p65 but decreased protein expression of MFN2, Tom20, and PGC-1α; decreased mitochondrial membrane potential and mass; and increased ROS levels and NF-κB p65 nuclear translocation. Salidroside intervention decreased mRNA expression of interleukin-1β and tumor necrosis factor-α compared with the M1 group but did not affect that of iNOS. Furthermore, salidroside intervention prevented the changes in protein expression, mitochondrial membrane potential and mass, ROS levels, and NF-κB p65 nuclear translocation observed in the M1 group. In summary, salidroside ultimately inhibits M1 macrophage polarization and maintains mitochondrial homeostasis after macrophage polarization by increasing mitochondrial membrane potential, decreasing ROS levels, inhibiting NF-κB activation, and in turn regulating the expression of proinflammatory factors and mitochondrial homeostasis-associated proteins.

Therapeutic potential and molecular mechanisms of salidroside in ischemic diseases

Rhodiola is an ancient wild plant that grows in rock areas in high-altitude mountains with a widespread habitat in Asia, Europe, and America. From empirical belief to research studies, Rhodiola has undergone a long history of discovery, and has been used as traditional medicine in many countries and regions for treating high-altitude sickness, anoxia, resisting stress or fatigue, and for promoting longevity. Salidroside, a phenylpropanoid glycoside, is the main active component found in all species of Rhodiola. Salidroside could enhance cell survival and angiogenesis while suppressing oxidative stress and inflammation, and thereby has been considered a potential compound for treating ischemia and ischemic injury. In this article, we highlight the recent advances in salidroside in treating ischemic diseases, such as cerebral ischemia, ischemic heart disease, liver ischemia, ischemic acute kidney injury and lower limb ischemia. Furthermore, we also discuss the pharmacological functions and underlying molecular mechanisms. To our knowledge, this review is the first one that covers the protective effects of salidroside on different ischemia-related disease.

New insight into ischemic stroke: Circadian rhythm in post-stroke angiogenesis

The circadian rhythm is an endogenous clock system that coordinates and optimizes various physiological and pathophysiological processes, which accord with the master and the peripheral clock. Increasing evidence indicates that endogenous circadian rhythm disruption is involved in the lesion volume and recovery of ischemic stroke. As a critical recovery mechanism in post-stroke, angiogenesis reestablishes the regional blood supply and enhances cognitive and behavioral abilities, which is mainly composed of the following processes: endothelial cell proliferation, migration, and pericyte recruitment. The available evidence revealed that the circadian governs many aspects of angiogenesis. This study reviews the mechanism by which circadian rhythms regulate the process of angiogenesis and its contribution to functional recovery in post-stroke at the aspects of the molecular level. A comprehensive understanding of the circadian clock regulating angiogenesis in post-stroke is expected to develop new strategies for the treatment of cerebral infarction.

WKYMVm/FPR2 Alleviates Spinal Cord Injury by Attenuating the Inflammatory Response of Microglia

Spinal cord injury (SCI) is a common traumatic disease of the nervous system. The pathophysiological process of SCI includes primary injury and secondary injuries. An excessive inflammatory response leads to secondary tissue damage, which in turn exacerbates cellular and organ dysfunction. Due to the irreversibility of primary injury, current research on SCI mainly focuses on secondary injury, and the inflammatory response is considered the primary target. Thus, modulating the inflammatory response has been suggested as a new strategy for the treatment of SCI. In this study, microglial cell lines, primary microglia, and a rat SCI model were used, and we found that WKYMVm/FPR2 plays an anti-inflammatory role and reduces tissue damage after SCI by suppressing the extracellular signal-regulated kinases 1 and 2 (ERK1/2) and nuclear factor-κB (NF-κB) signaling pathways. FPR2 was activated by WKYMVm, suppressing the secretion of tumor necrosis factor-α (TNF-α), interleukin-6 (IL-6), and interleukin-1β (IL-1β) by inhibiting M1 microglial polarization. Moreover, FPR2 activation by WKYMVm could reduce structural disorders and neuronal loss in SCI rats. Overall, this study illustrated that the activation of FPR2 by WKYMVm repressed M1 microglial polarization by suppressing the ERK1/2 and NF-κB signaling pathways to alleviate tissue damage and locomotor decline after SCI. These findings provide further insight into SCI and help identify novel treatment strategies.

The PI3K/AKT signalling pathway in inflammation, cell death and glial scar formation after traumatic spinal cord injury: Mechanisms and therapeutic opportunities

Objects

Traumatic spinal cord injury (TSCI) causes neurological dysfunction below the injured segment of the spinal cord, which significantly impacts the quality of life in affected patients. The phosphoinositide 3kinase/serine‐threonine kinase (PI3K/AKT) signaling pathway offers a potential therapeutic target for the inhibition of secondary TSCI. This review summarizes updates concerning the role of the PI3K/AKT pathway in TSCI.

Materials and Methods

By searching articles related to the TSCI field and the PI3K/AKT signaling pathway, we summarized the mechanisms of secondary TSCI and the PI3K/AKT signaling pathway; we also discuss current and potential future treatment methods for TSCI based on the PI3K/AKT signaling pathway.

Results

Early apoptosis and autophagy after TSCI protect the body against injury; a prolonged inflammatory response leads to the accumulation of pro‐inflammatory factors and excessive apoptosis, as well as excessive autophagy in the surrounding normal nerve cells, thus aggravating TSCI in the subacute stage of secondary injury. Initial glial scar formation in the subacute phase is a protective mechanism for TSCI, which limits the spread of damage and inflammation. However, mature scar tissue in the chronic phase hinders axon regeneration and prevents the recovery of nerve function. Activation of PI3K/AKT signaling pathway can inhibit the inflammatory response and apoptosis in the subacute phase after secondary TSCI; inhibiting this pathway in the chronic phase can reduce the formation of glial scar.

Conclusion

The PI3K/AKT signaling pathway has an important role in the recovery of spinal cord function after secondary injury. Inducing the activation of PI3K/AKT signaling pathway in the subacute phase of secondary injury and inhibiting this pathway in the chronic phase may be one of the potential strategies for the treatment of TSCI.

Salidroside attenuates high altitude hypobaric hypoxia-induced brain injury in mice via inhibiting NF-κB/NLRP3 pathway

Salidroside (Sal), an active ingredient from Rhodiola crenulate, has been reported to exert neuroprotection in cerebral injury from hypobaric hypoxia (HH) at high altitude. However, it remains to be understood whether its protective effects are related to inflammation suppression. In the present work, we aimed to reveal the mechanism of Sal attenuating HH-induced brain injury in mice caused by an animal hypobaric and hypoxic chamber. Our results provided that Sal could attenuate HH-evoked pathological injury and oxidative stress response by decreasing the content of ROS and MDA, and elevating the activities of SOD and GSH-Px. Sal treatment could partly enhance the energy metabolism, evidenced by increasing the activities of Na⁺-K⁺-ATPase, Ca²⁺-Mg²⁺-ATPase, ATP, SDH, HK and PK, while decreasing the release of LDH and LD. Meanwhile, Sal administration reversed the degradation of tight junction proteins ZO-1, Occludin and Claudin-5. Further, the increased levels of TNF-α, IL-1β and IL-6 were confined with Sal administration under the HH condition. Importantly, Sal could downregulate the proteins expression of p-NF-κB-p65, NLRP3, cleaved-Caspase-1 and ASC. Sal also decreased the protein expression of iNOS and COX2 with the increased CD206 and Arg1 expression. Taken together, these data provided that the inhibited NF-κB/NLRP3 pathway by Sal could attenuate HH-induced cerebral oxidative stress injury, inflammatory responses and the blood brain barrier (BBB) damage, attributing to the improved energy metabolism and the microglial phenotype of anti-inflammatory M2. The findings suggested that Sal was expected to be a promising anti-inflammatory agent for high altitude HH-induced brain injury.

Salidroside inhibits NLRP3 inflammasome activation and apoptosis in microglia induced by cerebral ischemia/reperfusion injury by inhibiting the TLR4/NF-κB signaling pathway

Background

The NOD-like receptor family pyrin domain-containing 3 (NLRP3) inflammasome is an important mediator of neuroinflammatory responses that regulates inflammatory injury following cerebral ischemia and may be a potential target. Salidroside (Sal) has good anti-inflammatory effects; however, it remains unclear whether Sal can regulate NLRP3 inflammasome activation through the Toll-like receptor 4 (TLR4)/nuclear factor kappa B (NF-κB) signaling pathway after cerebral ischemia to alleviate inflammatory injury.

Methods

We established an oxygen-glucose deprivation and reoxygenation (OGD/R) model of BV2 cells and a middle cerebral artery occlusion/reperfusion (MCAO/R) rat model. Cell Counting Kit-8 (CCK-8), flow cytometry and terminal deoxynucleotidyl transferase dUTP nick-end labeling (TUNEL) assay were used to detect the viability and apoptosis of BV2 cells. Enzyme-linked immunosorbent assay (ELISA) was used to detect the level of inflammatory factors. 2,3,5-triphenyltetrazolium chloride (TTC) staining and modified Neurological Severity Score (mNSS) were used to detect cerebral infarction volume and neurological deficit in rats. Western blot, immunohistochemistry and immunofluorescence staining were used to detect the protein expression levels.

Results

Our results showed that Sal increased viability, inhibited lactate dehydrogenase (LDH) release, and reduced apoptosis in OGD/R-induced BV2 cells. Sal reduced the levels of tumor necrosis factor-α (TNF-α), interleukin (IL)-6, and IL-8. Following induction by OGD/R, BV2 cells exhibited NLRP3 inflammasome activation and increased protein levels of NLRP3, apoptosis-associated speck-like protein containing a CARD (ASC), caspase-1, IL-1β, and IL-18. Protein levels of key TLR4 signaling pathway elements, such as TLR4, myeloid differentiation primary response 88 (MyD88), and phosphorylated nuclear factor kappa B p65 (p-NF-κB p65)/NF-κB p65 were upregulated. Interestingly, it was revealed that Sal could reverse these changes. In addition, TAK242, a specific inhibitor of TLR4, had the same effect as Sal treatment on BV2 cells following induction by OGD/R. In the MCAO/R rat model, Sal was also observed to inhibit NLRP3 inflammasome activation in microglia, reduce cerebral infarction volume, and inhibit apoptosis.

Conclusions

In summary, we found that Sal inhibited NLRP3 inflammasome activation and apoptosis in microglia induced by cerebral ischemia/reperfusion injury by inhibiting the TLR4/NF-κB signaling pathway, thus playing a protective role. Therefore, Sal may be a promising drug for the clinical treatment of ischemic stroke.

Protective Effect of Mild Hypothermia on Spinal Cord Ischemia-Induced Delayed Paralysis and Spinal Cord Injury

To explore the mechanism regarding the regulation of spinal cord ischemia (SCI) in rats by mild hypothermia. A SCI rat model was established through aorta occlusion, and in some cases, the rats were intervened with mild hypothermia, after which motor function, microglia activation, and M1/M2 polarization in rats were measured. Also, the expression of inflammatory cytokines (IL-1β, IL-6 and TNF-α) and neuronal apoptosis were examined. Lipopolysaccharide (LPS)-induced M1 microglia and IL-4-induced M2 microglia were intrathecally injected into rats to evaluate the effect of microglial polarization on SCI. In in vitro experiments, primary microglial cells were treated under hypothermic condition, in which M1/M2 polarization and microglia apoptosis, the levels of iNOS, CD86, CD206, Arg-1 and inflammatory cytokines were assessed. Western blot analysis detected the activation of the TLR4/NF-κB pathway to investigate the role of this pathway in M1/M2 polarization. SCI treatment impaired motor function, induced higher M1 microglia proportion, and increased the levels of pro-inflammatory cytokines in rats, and mild hypothermic treatment attenuated these trends. Moreover, injection of M1 microglia increased M1 microglia proportion and increased the levels of pro-inflammatory cytokines, while injection of M2 microglia induced the reverse results, i.e. decreased M1 microglia proportion and reduced pro-inflammatory cytokine levels. In LPS-induced microglial cells, mild hypothermia treatment increased M2 microglia proportion and decreased pro-inflammatory cytokine levels, relative to normothermia. Mild hypothermia inactivated the TLR4/NF-κB pathway in LPS-treated microglia. TLR4 overexpression reversed the function of mild hypothermia in LPS-stimulated microglia, and under normal condition, TLR4/NF-κB pathway suppressed microglial M2 polarization. Mild hypothermia inhibits TLR4/NF-κB pathway and promotes microglial M2 polarization, thus attenuating SCI-induced injury and inflammation.

The mechanism of microglia-mediated immune inflammation in ischemic stroke and the role of natural botanical components in regulating microglia: A review

Ischemic stroke (IS) is one of the most fatal diseases. Neuroimmunity, inflammation, and oxidative stress play important roles in various complex mechanisms of IS. In particular, the early proinflammatory response resulting from the overactivation of resident microglia and the infiltration of circulating monocytes and macrophages in the brain after cerebral ischemia leads to secondary brain injury. Microglia are innate immune cells in the brain that constantly monitor the brain microenvironment under normal conditions. Once ischemia occurs, microglia are activated to produce dual effects of neurotoxicity and neuroprotection, and the balance of the two effects determines the fate of damaged neurons. The activation of microglia is defined as the classical activation (M1 type) or alternative activation (M2 type). M1 type microglia secrete pro-inflammatory cytokines and neurotoxic mediators to exacerbate neuronal damage, while M2 type microglia promote a repairing anti-inflammatory response. Fine regulation of M1/M2 microglial activation to minimize damage and maximize protection has important therapeutic value. This review focuses on the interaction between M1/M2 microglia and other immune cells involved in the regulation of IS phenotypic characteristics, and the mechanism of natural plant components regulating microglia after IS, providing novel candidate drugs for regulating microglial balance and IS drug development.

Salidroside orchestrates metabolic reprogramming by regulating the Hif-1α signalling pathway in acute mountain sickness

CONTEXT

Rhodiola crenulata (Hook. f. et Thoms.) H. Ohba (Crassulaceae) is used to prevent and treat acute mountain sickness. However, the mechanisms underlying its effects on the central nervous system remain unclear.

OBJECTIVE

To investigate the effect of Rhodiola crenulata on cellular metabolism in the central nervous system.

MATERIALS AND METHODS

The viability and Hif-1α levels of microglia and neurons at 5% O₂ for 1, 3, 5 and 24 h were examined. We performed the binding of salidroside (Sal), rhodiosin, tyrosol and p-hydroxybenzyl alcohol to Hif-1α, Hif-1α, lactate, oxidative phosphorylation and glycolysis assays. Forty male C57BL/6J mice were divided into control and Sal (25, 50 and 100 mg/kg) groups to measure the levels of Hif-1α and lactate.

RESULTS

Microglia sensed low oxygen levels earlier than neurons, accompanied by elevated expression of Hif-1α protein. Salidroside, rhodiosin, tyrosol, and p-hydroxybenzyl alcohol decreased BV-2 (IC₅₀=1.93 ± 0.34 mM, 959.74 ± 10.24 μM, 7.47 ± 1.03 and 8.42 ± 1.63 mM) and PC-12 (IC₅₀=6.89 ± 0.57 mM, 159.28 ± 8.89 μM, 8.65 ± 1.20 and 8.64 ± 1.42 mM) viability. They (10 μM) reduced Hif-1α degradation in BV-2 (3.7-, 2.5-, 2.9- and 2.5-fold) and PC-12 cells (2.8-, 2.8-, 2.3- and 2.0-fold) under normoxia. Salidroside increased glycolytic capacity but attenuated oxidative phosphorylation. Salidroside (50 and 100 mg/kg) treatment increased the protein expression of Hif-1α and the release of lactate in the brain tissue of mice.

CONCLUSIONS

These results suggest that Sal induces metabolic reprogramming by regulating the Hif-1α signalling pathway to activate compensatory responses, which may be the core mechanism underlying the effect of Rhodiola crenulata on the central nervous system.

Uncovering the Metabolic Mechanism of Salidroside Alleviating Microglial Hypoxia Inflammation Based on Microfluidic Chip-Mass Spectrometry

Microglia are the main immune cells in the brain playing a critical role in neuroinflammation, and numerous pieces of evidence have proved that energy metabolism is closely associated with inflammation in activated microglia. Salidroside (Sal) isolated from Tibetan medicine Rhodiola crenulate can inhibit microglial hypoxia inflammation (HI). However, whether the inhibition is due to the intervening energy metabolic process in microglia is not clear. In this work, the hypoxic microenvironment of BV2 microglial cells was simulated using deferoxamine (DFO) in vitro and the change of cell metabolites (lactate, succinate, malate, and fumarate) was real-time online investigated based on a cell microfluidic chip-mass spectrometry (CM-MS) system. Meanwhile, for confirming the metabolic mechanism of BV2 cells under hypoxia, the level of HI-related factors (LDH, ROS, HIF-1α, NF-κB p65, TNF-α, IL-1β, and IL-6) was detected by molecular biotechnology. Integration of the detected results revealed that DFO-induced BV2 cell HI was associated with the process of energy metabolism, in which cell energy metabolism changed from oxidative phosphorylation to glycolysis. Furthermore, administration of Sal treatment could effectively invert this change, and two metabolites of Sal were identified: tyrosol and 4-hydroxyphenylacetic acid. In general, we illustrated a new mechanism of Sal for reducing BV2 cell HI injury and presented a novel analysis strategy that opened a way for real-time online monitoring of the energy metabolic mechanism of the effect of drugs on cells and further provided a superior strategy to screen natural drug candidates for HI-related brain disease treatment.