Melatonin Enhances the Therapeutic Effect of Plasma Exosomes Against Cerebral Ischemia-Induced Pyroptosis Through the TLR4/NF-κB Pathway

Neuroinflammation Targeting Pyroptosis: Molecular Mechanisms and Therapeutic Perspectives in Stroke

Pyroptosis is a recently identified type of pro-inflammatory programmed cell death (PCD) mediated by inflammasomes and nucleotide oligomerization domain-like receptors (NLs) and dependent on members of the caspase family. Pyroptosis has been widely reported to participate in the occurrence and progression of various inflammatory diseases, including stroke, a frequently lethal disease with high prevalence and many complications. To date, there have been no effectively therapeutic strategies and methods for treating stroke. Pyroptosis is thought to be closely related to the occurrence and development of stroke. Understanding inflammatory responses induced by the activation of pyroptosis would be hopeful to provide feasible approaches and strategies. Targeting on molecules in the upstream or downstream of pyroptosis pathway has shown promise in the treatment of stroke. The present review summarizes current research on the characteristics of pyroptosis, the function and pathological phenomena of pyroptosis in stroke, the molecule mechanisms related to inflammatory pathways, and the drugs and other molecules that can affect outcomes after stroke. These findings may help identify possible targets or new strategies for the diagnosis and treatment of stroke.

Plasma-derived exosomal hsa-miR-184 and hsa-mir-6766-3p as promising diagnostic biomarkers for early detection of children's cardiac surgery-associated acute kidney injury

There is little known about the contribution of exosomal microRNAs (exomiRs) in the children's cardiac surgery-associated acute kidney injury (CSA-AKI). This study aimed to find diagnostic biomarkers for predicting CSA-AKI in children. A prospective observational study was conducted from April 2020 to March 2021.According to the changes of serum creatinine (SCr) value and urine volume within 48 h, the children were divided into acute kidney injury (AKI) group and non-AKI group. Serum samples were collected 4 h after cardiac surgery. Isolation of extracellular vesicles (EVs) and extraction of exomiRs from serum samples. Illumina high-throughput sequencing was used to quantify exomiRs and screen candidate microRNAs (miRNAs). Expression levels of candidate miRNAs were validated using droplet digital polymerase chain reaction (ddPCR). Normal and injuried rats' kidney tissue were collected for tissue validation. In the pre-experimental stage (4 AKI vs. 4 non-AKI), hsa-miR-184, hsa-miR-4800-3p, hsa-miR-203a-3p and hsa-miR-6766-3p were selected as candidate genes. In the verification stage (8 AKI vs. 12 non-AKI), the expression of hsa-miR-184 in AKI group was significantly lower than that in non-AKI group (P = 0.031), and the expression of hsa-miR-4800-3p and hsa-miR-6766-3p in AKI group was significantly higher than that in non-AKI group (P = 0.01 and P = 0.047). There was no significant difference in the expression of hsa-miR-203a-3p between the two groups (P > 0.05). The expression of rats' kidney tissue rno-miR-184 in AKI group was significantly lower than that in the normal group (P = 0.044). The area under the curve (AUC) of AKI predicted by hsa-miR-184 is 0.7865 and the AUC of hsa-miR-6766-3p is 0.7708. Combined with two kinds of miRNAs, the area under the curve of AKI is predicted to be 0.8646. The change of exomiRs level in circulatory system occurred in the early stage after cardiac operation, and the changes of hsa-miR-184 and hsa-miR-6766-3p content in circulatory system could predict CSA-AKI well.

The role of extracellular vesicles in pyroptosis-mediated infectious and non-infectious diseases

Pyroptosis, a lytic and pro-inflammatory cell death, is important in various pathophysiological processes. Host- and bacteria-derived extracellular vesicles (EVs), as natural nanocarriers messengers, are versatile mediators of intercellular communication between different types of cells. Recently, emerging research has suggested that EVs exhibit multifaceted roles in disease progression by manipulating pyroptosis. This review focuses on new findings concerning how EVs shape disease progression in infectious and non-infectious diseases by regulating pyroptosis. Understanding the characteristics and activity of EVs-mediated pyroptotic death may conducive to the discovery of novel mechanisms and more efficient therapeutic targets in infectious and non-infectious diseases.

Exosomes: A Cellular Communication Medium That Has Multiple Effects On Brain Diseases

Exosomes, as membranous vesicles generated by multiple cell types and secreted to extracellular space, play a crucial role in a range of brain injury-related brain disorders by transporting diverse proteins, RNA, DNA fragments, and other functional substances. The nervous system's pathogenic mechanisms are complicated, involving pathological processes like as inflammation, apoptosis, oxidative stress, and autophagy, all of which result in blood-brain barrier damage, cognitive impairment, and even loss of normal motor function. Exosomes have been linked to the incidence and progression of brain disorders in recent research. As a result, a thorough knowledge of the interaction between exosomes and brain diseases may lead to the development of more effective therapeutic techniques that may be implemented in the clinic. The potential role of exosomes in brain diseases and the crosstalk between exosomes and other pathogenic processes were discussed in this paper. Simultaneously, we noted the delicate events in which exosomes as a media allow the brain to communicate with other tissues and organs in physiology and disease, and compiled a list of natural compounds that modulate exosomes, in order to further improve our understanding of exosomes and propose new ideas for treating brain disorders.

Prolonged exposure to NaAsO2 induces thyroid dysfunction and inflammatory injury in Sprague‒Dawley rats, involvement of NLRP3 inflammasome‒mediated pyroptosis

Arsenic, a well-known hazardous toxicant, has been found in recent years to act as an environmental endocrine disruptor that accumulates in various endocrine organs, impeding the normal physiological functions of these organs and altering hormone secretion levels. Moreover, some research has demonstrated a correlation between arsenic exposure and thyroid functions, suggesting that arsenic has a toxicological effect on the thyroid gland. However, the specific type of thyroid gland damage caused by arsenic exposure and its potential molecular mechanism remain poorly understood. In this study, the toxic effects of sodium arsenite (NaAsO2) exposure at different doses (0, 2.5, 5.0 and 10.0 mg/kg bw) and over different durations (12, 24 and 36 weeks) on thyroid tissue and thyroid hormone levels in Sprague‒Dawley (SD) rats were investigated, and the specific mechanisms underlying the effects were also explored. Our results showed that NaAsO2 exposure can cause accumulation of this element in the thyroid tissue of rats. More importantly, chronic exposure to NaAsO2 significantly upregulated the expression of NLRP3 inflammasome-related proteins in thyroid tissue, leading to pyroptosis of thyroid cells and subsequent development of thyroid dysfunction, inflammatory injury, epithelial-mesenchymal transition (EMT), and even fibrotic changes in the thyroid glands of SD rats. These findings increase our understanding of the toxic effects of arsenic exposure on the thyroid gland and its functions.

Exosomes as therapeutic and drug delivery vehicle for neurodegenerative diseases

Neurodegenerative disorders are complex, progressive, and life-threatening. They cause mortality and disability for millions of people worldwide. Appropriate treatment for neurodegenerative diseases (NDs) is still clinically lacking due to the presence of the blood-brain barrier (BBB). Developing an effective transport system that can cross the BBB and enhance the therapeutic effect of neuroprotective agents has been a major challenge for NDs. Exosomes are endogenous nano-sized vesicles that naturally carry biomolecular cargoes. Many studies have indicated that exosome content, particularly microRNAs (miRNAs), possess biological activities by targeting several signaling pathways involved in apoptosis, inflammation, autophagy, and oxidative stress. Exosome content can influence cellular function in healthy or pathological ways. Furthermore, since exosomes reflect the features of the parental cells, their cargoes offer opportunities for early diagnosis and therapeutic intervention of diseases. Exosomes have unique characteristics that make them ideal for delivering drugs directly to the brain. These characteristics include the ability to pass through the BBB, biocompatibility, stability, and innate targeting properties. This review emphasizes the role of exosomes in alleviating NDs and discusses the associated signaling pathways and molecular mechanisms. Furthermore, the unique biological features of exosomes, making them a promising natural transporter for delivering various medications to the brain to combat several NDs, are also discussed.

Significance of Melatonin in the Regulation of Circadian Rhythms and Disease Management

Melatonin, the 'hormone of darkness' is a neuronal hormone secreted by the pineal gland and other extra pineal sites. Responsible for the circadian rhythm and seasonal behaviour of vertebrates and mammals, melatonin is responsible for regulating various physiological conditions and the maintenance of sleep, body weight and the neuronal activities of the ocular sites. With its unique amphiphilic structure, melatonin can cross the cellular barriers and elucidate its activities in the subcellular components, including mitochondria. Melatonin is a potential scavenger of oxygen and nitrogen-reactive species and can directly obliterate the ROS and RNS by a receptor-independent mechanism. It can also regulate the pro- and anti-inflammatory cytokines in various pathological conditions and exhibit therapeutic activities against neurodegenerative, psychiatric disorders and cancer. Melatonin is also found to show its effects on major organs, particularly the brain, liver and heart, and also imparts a role in the modulation of the immune system. Thus, melatonin is a multifaceted candidate with immense therapeutic potential and is still considered an effective supplement on various therapies. This is primarily due to rectification of aberrant circadian rhythm by improvement of sleep quality associated with risk development of neurodegenerative, cognitive, cardiovascular and other metabolic disorders, thereby enhancing the quality of life.

Targeting pyroptosis to treat ischemic stroke: From molecular pathways to treatment strategy

Ischemic stroke is the primary reason for human disability and death, but the available treatment options are limited. Hence, it is imperative to explore novel and efficient therapies. In recent years, pyroptosis (a pro-inflammatory cell death characterized by inflammation) has emerged as an important pathological mechanism in ischemic stroke that can cause cell death through plasma membrane rupture and release of inflammatory cytokines. Pyroptosis is closely associated with inflammation, which exacerbates the inflammatory response in ischemic stroke. The level of inflammasomes, GSDMD, Caspases, and inflammatory factors is increased after ischemic stroke, exacerbating brain injury by mediating pyroptosis. Hence, inhibition of pyroptosis can be a therapeutic strategy for ischemic stroke. In this review, we have summarized the relationship between pyroptosis and ischemic stroke, as well as a series of treatments to attenuate pyroptosis, intending to provide insights for new therapeutic targets on ischemic stroke.

Exosomes derived from HUVECs alleviate ischemia-reperfusion induced inflammation in neural cells by upregulating KLF14 expression

Neuroinflammation plays a key role in the progression of secondary brain injury after ischemic stroke, and exosomes have been increasingly recognized to eliminate inflammatory responses through various mechanisms. This study aimed to explore the effect and possible mechanism of human umbilical vein endothelial cells derived exosomes (H-EXOs) on neuroinflammation. We established a transient middle cerebral artery occlusion/reperfusion (tMCAO/R) in male rats and oxygen-glucose-deprivation/reoxygenation (OGD/R) model in cultured neurons to mimic secondary brain injury after ischemic stroke in vivo. H-EXOs were administered at the same time of reperfusion. Results showed that the production of pro-inflammatory cytokines TNF-α, IL-1β, and IL-6, and the transcription factor Krüppel-like factor 14 (KLF14) were significantly increased both in rat brain tissue and cultured neural cells after ischemic-reperfusion (I/R) injury. H-EXOs treatment significantly improved the cultured cell viability, reduced infarct sizes, mitigated neurobehavioral defects, and alleviated the expression of pro-inflammatory cytokines compared with the control group, indicating that H-EXOs exerted anti-inflammatory effect against I/R injury. Further studies revealed that the anti-inflammatory effect of H-EXOs could be weakened by small-interfering RNA (siKLF4) transfection. KLF14 was a protective factor produced during cerebral ischemia-reperfusion injury. In conclusion, H-EXOs protect neurons from inflammation after I/R injury by enhancing KLF14 expression.

STAT4-Mediated Klotho Up-Regulation Contributes to the Brain Ischemic Tolerance by Cerebral Ischemic Preconditioning via Inhibiting Neuronal Pyroptosis

Our previous study has proved that the Klotho up-regulation participated in cerebral ischemic preconditioning (CIP)-induced brain ischemic tolerance. However, the exact neuroprotective mechanism of Klotho in CIP remains unclear. We explored the hypothesis that STAT4-mediated Klotho up-regulation contributes to the CIP-induced brain ischemic tolerance via inhibiting neuronal pyroptosis. Firstly, the expressions of pyroptosis-associated proteins (i.e., NLRP3, GSDMD, pro-caspase-1, and cleaved caspase-1) in hippocampal CA1 region were determined during the process of brain ischemic tolerance. We found the expression of pyroptosis-associated proteins was significantly up-regulated in the ischemic insult (II) group, and showed no significant changes in the CIP group. The expression level of each pyroptosis-associated proteins was lower in the CIP + II group than that in the II group. Inhibition of Klotho expression increased the expression of pyroptosis-associated proteins in the CIP + II group and blocked the CIP-induced brain ischemic tolerance. Injection of Klotho protein decreased the expression of pyroptosis-associated proteins in the II group, and protected neurons from ischemic injury. Secondly, the transcription factor STAT4 of Klotho was identified by bioinformatic analysis. Double luciferase reporter gene assay and chromatin immunoprecipitation assay showed STAT4 can bind to the site between nt - 881 and - 868 on the Klotho promoter region and positively regulates Klotho expression. Moreover, we found CIP significantly enhanced the expression of STAT4. Knockdown STAT4 suppressed Klotho up-regulation after CIP and blocked the CIP-induced brain ischemic tolerance. Collectively, it can be concluded that STAT4-mediated the up-regulation of Klotho contributed to the brain ischemic tolerance induced by CIP via inhibiting pyroptosis.

Electroacupuncture Ameliorates Neuronal Injury by NLRP3/ASC/Caspase-1 Mediated Pyroptosis in Cerebral Ischemia-Reperfusion

NLRP3/ASC/Caspase-1 mediated pyroptosis is one of the important causes of cerebral ischemia-reperfusion (I/R) injury. Electroacupuncture (EA) is widely used in clinical treatment of ischemic stroke. However, mechanism of EA on ischemic stroke remains unclear. Therefore, on basis of a previous work, this study used middle cerebral artery occlusion (MCAO) 2 h and then reperfusion 7 days in rats to simulate brain I/R process. EA with Bahui (GV20) and Zusanli (ST36) and VX-765 (a specific inhibitor of Caspase-1) was performed. In this study, we found that EA improved cerebral infarct size and neuronal damage, including ultrastructural injury, and ameliorated nitro/oxidative stress in cerebral I/R. Additionally, EA treatment significantly decreased ASC, Caspase-1, GSDMD, and IL-1β expression and VX-765 treatment significantly decreased NLRP3, Caspase-1, and IL-1β expression. This proved that EA can regulate NLRP3/ASC/Caspase-1 mediated pyroptosis, improve neuronal injury during cerebral I/R, and provide basic experimental data for clinical treatment.

Therapeutic strategies targeting the NLRP3‑mediated inflammatory response and pyroptosis in cerebral ischemia/reperfusion injury (Review)

Ischemic stroke poses a major threat to human health. Therefore, the molecular mechanisms of cerebral ischemia/reperfusion injury (CIRI) need to be further clarified, and the associated treatment approaches require exploration. The NOD‑like receptor thermal protein domain associated protein 3 (NLRP3) inflammasome serves an important role in causing CIRI, and its activation exacerbates the underlying injury. Activation of the NLRP3 inflammasome triggers the maturation and production of the inflammatory molecules IL‑1β and IL‑18, as well as gasdermin‑D‑mediated pyroptosis and CIRI damage. Thus, the NLRP3 inflammasome may be a viable target for the treatment of CIRI. In the present review, the mechanisms of the NLRP3 inflammasome in the intense inflammatory response and pyroptosis induced by CIRI are discussed, and the therapeutic strategies that target the NLRP3‑mediated inflammatory response and pyroptosis in CIRI are summarized. At present, certain drugs have already been studied, highlighting future therapeutic perspectives.

Emerging role of exosomes in ulcerative colitis: Targeting NOD-like receptor family pyrin domain containing 3 inflammasome

Ulcerative colitis (UC) is a chronic recurrent inflammatory bowel disease. Despite ongoing advances in our understanding of UC, its pathogenesis is yet unelucidated, underscoring the urgent need for novel treatment strategies for patients with UC. Exosomes are nanoscale membrane particles that mediate intercellular communication by carrying various bioactive molecules, such as proteins, RNAs, DNA, and metabolites. The NOD-like receptor family pyrin domain containing 3 (NLRP3) inflammasome is a cytosolic tripartite protein complex whose activation induces the maturation and secretion of proinflammatory cytokines interleukin-1β (IL-1β) and IL-18, triggering the inflammatory response to a pathogenic agent or injury. Growing evidence suggests that exosomes are new modulators of the NLRP3 inflammasome, with vital roles in the pathological process of UC. Here, recent evidence is reviewed on the role of exosomes and NLRP3 inflammasome in UC. First, the dual role of exosomes on NLRP3 inflammasome and the effect of NLRP3 inflammasome on exosome secretion are summarized. Finally, an outlook on the directions of exosome-NLRP3 inflammasome crosstalk research in the context of UC is proposed and areas of further research on this topic are highlighted.

Exosomes-Mediated Signaling Pathway: A New Direction for Treatment of Organ Ischemia-Reperfusion Injury

Ischemia reperfusion (I/R) is a common pathological process which occurs mostly in organs like the heart, brain, kidney, and lung. The injury caused by I/R gradually becomes one of the main causes of fatal diseases, which is an urgent clinical problem to be solved. Although great progress has been made in therapeutic methods, including surgical, drug, gene therapy, and transplant therapy for I/R injury, the development of effective methods to cure the injury remains a worldwide challenge. In recent years, exosomes have attracted much attention for their important roles in immune response, antigen presentation, cell migration, cell differentiation, and tumor invasion. Meanwhile, exosomes have been shown to have great potential in the treatment of I/R injury in organs. The study of the exosome-mediated signaling pathway can not only help to reveal the mechanism behind exosomes promoting reperfusion injury recovery, but also provide a theoretical basis for the clinical application of exosomes. Here, we review the research progress in utilizing various exosomes from different cell types to promote the healing of I/R injury, focusing on the classical signaling pathways such as PI3K/Akt, NF-κB, Nrf2, PTEN, Wnt, MAPK, toll-like receptor, and AMPK. The results suggest that exosomes regulate these signaling pathways to reduce oxidative stress, regulate immune responses, decrease the expression of inflammatory cytokines, and promote tissue repair, making exosomes a competitive emerging vector for treating I/R damage in organs.

The role and therapeutic potential of nuclear factor κB (NF-κB) in ischemic stroke

Stroke is a prevalent cerebrovascular condition with a global impact, causing significant rates of illness and death. Despite extensive research, the available treatment options for stroke remain restricted. Hence, it is crucial to gain a deeper understanding of the molecular mechanisms associated with the onset and advancement of stroke in order to establish a theoretical foundation for novel preventive and therapeutic approaches. NF-κB, also known as nuclear factor κB, is a transcription factor responsible for controlling the expression of numerous genes and plays a crucial role in diverse physiological processes. NF-κB is triggered and regulates neuroinflammation and other processes after stroke, promoting the generation of cytokine storms and contributing to the advancement of ischemic stroke (IS). Therefore, NF-κB could potentially play a vital role in stroke by regulating diverse pathophysiological processes. This review provides an overview of the functions of NF-κB in stroke and its governing mechanisms. In addition, our attention is directed towards various potential therapies that aim to inhibit the NF-κB signaling pathway in order to offer valuable insights for the advancement of innovative treatment approaches for stroke.

MiR-184-5p represses neuropathic pain by regulating CCL1/CCR8 signaling interplay in the spinal cord in diabetic mice

BACKGROUND

Diabetic neuropathic pain (DNP) is a serious complication for diabetic patients involving nervous system. MicroRNAs (miRNAs) are small-noncoding RNAs which are dysregulated in neuropathic pain, and might be critical molecules for pain treatment. Our previous study has shown miR-184-5p was significantly downregulated in DNP. Therefore, the mechanism of miR-184-5p in DNP was investigated in this study.

METHODS

A DNP model was established through streptozotocin (STZ). The pharmacological tools were injected intrathecally, and pain behavior was evaluated by paw withdrawal mechanical thresholds (PWMTs). Bioinformatics analysis, Dual-luciferase reporter assay and fluorescence-in-situ-hybridization (FISH) were used to seek and confirm the potential target genes of miR-184-5p. The expression of relative genes and proteins was analyzed by quantitative reverse transcriptase real-time PCR (qPCR) and western blotting.

RESULTS

MiR-184-5p expression was down-regulated in spinal dorsal on days 7 and 14 after STZ, while intrathecal administration of miR-184-5p agomir attenuates neuropathic pain induced by DNP and intrathecal miR-184-5p antagomir induces pain behaviors in naïve mice. Chemokine CC motif ligand 1 (CCL1) was found to be a potential target of miR-184-5p and the protein expression of CCL1 and the mRNA expression of CCR8 were up-regulated in spinal dorsal on days 7 and 14 after STZ. The luciferase reporter assay and FISH demonstrated that CCL1 is a direct target of miR-184-5p. MiR-184-5p overexpression attenuated the expression of CCL1/CCR8 in DNP; intrathecal miR-184-5p antagomir increased the expression of CCL1/CCR8 in spinal dorsal of naïve mice.

CONCLUSION

This research illustrates that miR-184-5p alleviates DNP through the inhibition of CCL1/CCR8 signaling expression.

Regulated necrosis pathways: a potential target for ischemic stroke

Globally, ischemic stroke causes millions of deaths per year. The outcomes of ischemic stroke are largely determined by the amount of ischemia-related and reperfusion-related neuronal death in the infarct region. In the infarct region, cell injuries follow either the regulated pathway involving precise signaling cascades, such as apoptosis and autophagy, or the nonregulated pathway, which is uncontrolled by any molecularly defined effector mechanisms such as necrosis. However, numerous studies have recently found that a certain type of necrosis can be regulated and potentially modified by drugs and is nonapoptotic; this type of necrosis is referred to as regulated necrosis. Depending on the signaling pathway, various elements of regulated necrosis contribute to the development of ischemic stroke, such as necroptosis, pyroptosis, ferroptosis, pathanatos, mitochondrial permeability transition pore-mediated necrosis and oncosis. In this review, we aim to summarize the underlying molecular mechanisms of regulated necrosis in ischemic stroke and explore the crosstalk and interplay among the diverse types of regulated necrosis. We believe that targeting these regulated necrosis pathways both pharmacologically and genetically in ischemia-induced neuronal death and protection could be an efficient strategy to increase neuronal survival and regeneration in ischemic stroke.

Neural Stem Cell Extracellular Vesicles Carrying YBX1 Inhibited Neuronal Pyroptosis Through Increasing m6A-modified GPR30 Stability and Expression in Ischemic Stroke

Neural stem cell-derived extracellular vesicles (NSC-derived EVs) alleviated ischemic stroke (IS) by suppressing the activation of nucleotide-binding domain leucine-rich repeats family protein 3 (NLRP3) inflammasome and neuronal pyroptosis. However, the specific mechanism needs further investigation. qRT-qPCR, Western blotting, and immunofluorescence detected related gene expression. Immunofluorescent analyzed the expression of Ki-67, βIII-Tubulin (Tuj1), and GFAP. Lactate dehydrogenase (LDH) release and IL-1β and IL-18 levels were analyzed by LDH and ELISA kits. TTC staining evaluated the infarction of brain tissues. Flow cytometric analysis measured caspase-1 activity. M6A methylated RNA immunoprecipitation PCR (MeRIP-PCR) measured methylation levels of G protein-coupled receptor 30 (GPR30). RIP and Co-IP analyzed the interactions of Y box binding protein (YBX1)/GPR30, YBX1/IGF2BP1 and NLRP3/speckle-type POZ protein (SPOP), as well as the ubiquitination levels of NLRP3. NSC-derived EVs inhibited the ischemia-reperfusion (I/R) injury of rats and the neuronal pyroptosis induced by oxygen-glucose deprivation/reoxygenation (OGD/R). Knockdown of EVs carrying YBX1 or GPR30 silencing abolished these inhibiting effects. GPR30 mRNA and IGF2BP1 protein were enriched by YBX1 antibody. YBX1 enhanced the stability of m6A-modified GPR30 by interacting with IGF2BP1 and thus promoting GPR30 expression. Knockdown of IGF2BP1 suppressed the binding between YBX1 and GPR30 mRNA. GPR30 promoted NLRP3 ubiquitination by interacting with SPOP. EVs carrying YBX1 could reduce the infarction of brain tissues and inhibit neuronal pyroptosis in rats with I/R injury. NSC-derived EVs carrying YBX1 increased the stability of m6A-modified GPR30 by interacting with IGF2BP1; the upregulation of GPR30 inhibited the activation of NLRP3 inflammasome through promoting NLRP3 ubiquitination by SPOP, ultimately suppressing the neuronal pyroptosis in IS.

To re-examine the intersection of microglial activation and neuroinflammation in neurodegenerative diseases from the perspective of pyroptosis

Neurodegenerative diseases (NDs), such as Alzheimer's disease, Parkinson's disease, Huntington's disease, and motor neuron disease, are diseases characterized by neuronal damage and dysfunction. NDs are considered to be a multifactorial disease with diverse etiologies (immune, inflammatory, aging, genetic, etc.) and complex pathophysiological processes. Previous studies have found that neuroinflammation and typical microglial activation are important mechanisms of NDs, leading to neurological dysfunction and disease progression. Pyroptosis is a new mode involved in this process. As a form of programmed cell death, pyroptosis is characterized by the expansion of cells until the cell membrane bursts, resulting in the release of cell contents that activates a strong inflammatory response that promotes NDs by accelerating neuronal dysfunction and abnormal microglial activation. In this case, abnormally activated microglia release various pro-inflammatory factors, leading to the occurrence of neuroinflammation and exacerbating both microglial and neuronal pyroptosis, thus forming a vicious cycle. The recognition of the association between pyroptosis and microglia activation, as well as neuroinflammation, is of significant importance in understanding the pathogenesis of NDs and providing new targets and strategies for their prevention and treatment.

Non-Excitatory Amino Acids, Melatonin, and Free Radicals: Examining the Role in Stroke and Aging

The aim of this review is to explore the relationship between melatonin, free radicals, and non-excitatory amino acids, and their role in stroke and aging. Melatonin has garnered significant attention in recent years due to its diverse physiological functions and potential therapeutic benefits by reducing oxidative stress, inflammation, and apoptosis. Melatonin has been found to mitigate ischemic brain damage caused by stroke. By scavenging free radicals and reducing oxidative damage, melatonin may help slow down the aging process and protect against age-related cognitive decline. Additionally, non-excitatory amino acids have been shown to possess neuroprotective properties, including antioxidant and anti-inflammatory in stroke and aging-related conditions. They can attenuate oxidative stress, modulate calcium homeostasis, and inhibit apoptosis, thereby safeguarding neurons against damage induced by stroke and aging processes. The intracellular accumulation of certain non-excitatory amino acids could promote harmful effects during hypoxia-ischemia episodes and thus, the blockade of the amino acid transporters involved in the process could be an alternative therapeutic strategy to reduce ischemic damage. On the other hand, the accumulation of free radicals, specifically mitochondrial reactive oxygen and nitrogen species, accelerates cellular senescence and contributes to age-related decline. Recent research suggests a complex interplay between melatonin, free radicals, and non-excitatory amino acids in stroke and aging. The neuroprotective actions of melatonin and non-excitatory amino acids converge on multiple pathways, including the regulation of calcium homeostasis, modulation of apoptosis, and reduction of inflammation. These mechanisms collectively contribute to the preservation of neuronal integrity and functions, making them promising targets for therapeutic interventions in stroke and age-related disorders.

Mechanism of Resveratrol Improving Ischemia-Reperfusion Injury by Regulating Microglial Function Through microRNA-450b-5p/KEAP1/Nrf2 Pathway

Alterations in the M1/M2 polarization phenotype significantly affect disease progression. Antioxidant and anti-inflammatory protective effects of resveratrol (Res) have been demonstrated. This paper tested the hypothesis that Res could protect against cerebral ischemia-reperfusion injury (CI/RI) by modulating microglial polarization via the miR-450b-5p/KEAP1/Nrf2 pathway. Rats were first treated with Res and adenovirus that interfered with miR-450b-5p or KEAP1, and then established a middle cerebral artery occlusion-reperfusion model using modified nylon sutures. Rats were then evaluated for neurological and behavioral functions, and markers of M2 microglia were detected by immunofluorescence staining. Additionally, the signature patterns of miR-450b-5p, KEAP1, and Nrf2 were determined. The collected data demonstrated that Res exerted neuroprotective effects in CI/RI by promoting microglial M2 polarization. Additionally, Res could regulate the Nrf2 pathway by targeting KEAP1 by up-regulating miR-450b-5p. Up-regulating miR-450b-5p or down-regulating KEAP1 could further promote the protective effect of Res, while down-regulating miR-450b-5p or up-regulating KEAP1 worked oppositely. Our study demonstrates that Res exerts neuroprotective effects on microglial M2 polarization through the miR-450b-5p/KEAP1/Nrf2 pathway during CI/RI.

Biliverdin modulates the Nrf2/A20/eEF1A2 axis to alleviate cerebral ischemia-reperfusion injury by inhibiting pyroptosis

This study aimed to examine whether Biliverdin, which is a common metabolite of haem, can alleviate cerebral ischemia reperfusion injury (CIRI) by inhibiting pyroptosis. Here, CIRI was induced by middle cerebral artery occlusion-reperfusion (MCAO/R) in C57BL/6 J mice and modelled by oxygen and glucose deprivation/reoxygenation (OGD/R) in HT22 cells, it was treated with or without Biliverdin. The spatiotemporal expression of GSDMD-N and infarction volumes were assessed by immunofluorescence staining and triphenyltetrazolium chloride (TTC), respectively. The NLRP3/Caspase-1/GSDMD pathway, which is central to the pyroptosis process, as well as the expression of Nrf2, A20, and eEF1A2 were determined by Western-blots. Nrf2, A20, and eEF1A2 interactions were verified using dual-luciferase reporter assays, chromatin immunoprecipitation, or co-immunoprecipitation. Additionally, the role of Nrf2/A20/eEF1A2 axis in modulating the neuroprotective properties of Biliverdin was investigated using A20 or eEF1A2 gene interference (overexpression and/or silencing). 40 mg/kg of Biliverdin could significantly alleviate CIRI both in vivo and in vitro, promoted the activation of Nrf2, elevated A20 expression, but decreased eEF1A2 expression. Nrf2 can bind to the promoter of A20, thereby transcriptionally regulating the expression of A20. A20 can furthermore interacted with eEF1A2 through its ZnF4 domain to ubiquitinate and degrade it, leading to the downregulation of eEF1A2. Our studies have also demonstrated that either the knock-down of A20 or over-expression of eEF1A2 blunted the protective effect of Biliverdin. Rescue experiments further confirmed that Biliverdin could regulate the NF-κB pathway via the Nrf2/A20/eEF1A2 axis. In summary, our study demonstrates that Biliverdin ameliorates CIRI by inhibiting the NF-κB pathway via the Nrf2/A20/eEF1A2 axis. Our findings can help identify novel therapeutic targets for the treatment of CIRI.

Melatonin: a promising neuroprotective agent for cerebral ischemia-reperfusion injury

Cerebral ischemia-reperfusion (CIR) injury is initiated by the generation of reactive oxygen species (ROS), which leads to the oxidation of cellular proteins, DNA, and lipids as an initial event. The reperfusion process impairs critical cascades that support cell survival, including mitochondrial biogenesis and antioxidant enzyme activity. Failure to activate prosurvival signals may result in increased neuronal cell death and exacerbation of CIR damage. Melatonin, a hormone produced naturally in the body, has high concentrations in both the cerebrospinal fluid and the brain. However, melatonin production declines significantly with age, which may contribute to the development of age-related neurological disorders due to reduced levels. By activating various signaling pathways, melatonin can affect multiple aspects of human health due to its diverse range of activities. Therefore, understanding the underlying intracellular and molecular mechanisms is crucial before investigating the neuroprotective effects of melatonin in cerebral ischemia-reperfusion injury.

Melatonin modulates the aggravation of pyroptosis, necroptosis, and neuroinflammation following cerebral ischemia and reperfusion injury in obese rats

Obesity is well-established as a common comorbidity in ischemic stroke. The increasing evidence has revealed that it also associates with the exacerbation of brain pathologies, resulting in increasingly severe neurological outcomes following cerebral ischemia and reperfusion (I/R) damage. Mechanistically, pyroptosis and necroptosis are novel forms of regulated death that relate to the propagation of inflammatory signals in case of cerebral I/R. Previous studies noted that pyroptotic and necroptotic signaling were exacerbated in I/R brain of obese animals and led to the promotion of brain tissue injury. This study aimed to investigate the roles of melatonin on pyroptosis, necroptosis, and pro-inflammatory pathways occurring in the I/R brain of obese rats. Male Wistar rats were given a high-fat diet for 16 weeks to induce the obese condition, and then were divided into 4 groups: Sham-operated, I/R treated with vehicle, I/R treated with melatonin (10 mg/kg), and I/R treated with glycyrrhizic acid (10 mg/kg). All drugs were administered via intraperitoneal injection at the onset of reperfusion. The development of neurological deficits, cerebral infarction, histological changes, neuronal death, and glial cell hyperactivation were investigated. This study revealed that melatonin effectively improved these detrimental parameters. Furthermore, the processes of pyroptosis, necroptosis, and inflammation were all diminished by melatonin treatment. A summary of the findings is that melatonin effectively reduces ischemic brain pathology and thereby improves post-stroke outcomes in obese rats by modulating pyroptosis, necroptosis, and inflammation.

Gut microbiome plays a vital role in post-stroke injury repair by mediating neuroinflammation

Cerebral stroke is a common neurological disease and often causes severe neurological deficits. With high morbidity, mortality, and disability rates, stroke threatens patients' life quality and brings a heavy economic burden on society. Ischemic cerebral lesions incur pathological changes as well as spontaneous nerve repair following stroke. Strategies such as drug therapy, physical therapy, and surgical treatment, can ameliorate blood and oxygen supply in the brain, hamper the inflammatory responses and maintain the structural and functional integrity of the brain. The gut microbiome, referred to as the "second genome" of the human body, participates in the regulation of multiple physiological functions including metabolism, digestion, inflammation, and immunity. The gut microbiome is not only inextricably associated with dangerous factors pertaining to stroke, including high blood pressure, diabetes, obesity, and atherosclerosis, but also influences stroke occurrence and prognosis. AMPK functions as a hub of metabolic control and is responsible for the regulation of metabolic events under physiological and pathological conditions. The AMPK mediators have been found to exert dual roles in regulating gut microbiota and neuroinflammation/neuronal apoptosis in stroke. In this study, we reviewed the role of the gut microbiome in cerebral stroke and the underlying mechanism of the AMPK signaling pathway in stroke. AMPK mediators in nerve repair and the regulation of intestinal microbial balance were also summarized.

The role of NLRP3 inflammasome-mediated pyroptosis in ischemic stroke and the intervention of traditional Chinese medicine

Ischemic stroke (IS) is the second leading cause of death and disability in the world. Pyroptosis, a form of programmed cell death initiated by caspases, participates in the occurrence and development of IS. Because it can increase cell membrane permeability, mediate the release of inflammatory factors, and aggravate inflammation, inhibiting this process can significantly reduce the pathological injury of IS. The nucleotide binding oligomerization domain-like receptor family pyrin domain protein 3 (NLRP3) is a multiprotein complex whose activation is the core link of pyroptosis. In recent years, studies have reported that traditional Chinese medicine (TCM) could regulate pyroptosis mediated by NLRP3 inflammasome through multi-channel and multi-target networks and thus exert the effect against IS. This article reviews 107 papers published in recent years in PubMed, Chinese National Knowledge Infrastructure (CNKI), and WanFang Data in recent years. It has found that the activation factors of NLRP3 inflammasome include ROS, mitochondrial dysfunction, K⁺, Ca²⁺, lysosome rupture, and trans-Golgi breakdown. TLR4/NF-κB/NLRP3, ROS/TXNIP/NLRP3, AMPK/Nrf2/NLRP3, DRP1/NLRP3, TAK1/JNK/NLRP3 signaling pathways regulate the initiation and assembly of the NLRP3 inflammasome, subsequently induce pyroptosis, affecting the occurrence and development of IS. TCM can affect the above signaling pathways and regulate the pyroptosis mediated by NLRP3 inflammasome, so as to play a protective role against IS, which provides a new entry point for discussing the pathological mechanism of IS and a theoretical basis for developing TCM treasure house.

Biopharmaceutical, preclinical pharmacokinetic and pharmaco-dynamic investigations of an orally administered novel 3-nbutylphthalide prodrug for ischemic stroke treatment

Ischemic stroke (IS) has been contributing in leading causes of disability and death worldwide and the cases are still increasing. In China, naturally sourced compound 3-n-butylphthalide (NBP) is widely applied in clinical practice for IS treatment with established evidences of efficacy and safety. However, NBP is an oily liquid at room temperature and has no active brain targeting ability, quite limiting its broader application in clinical practice. Via intravenous injection (i.v.) a prodrug compound (DB1) we previously developed deriving from NBP had dramatically enhanced the pharmacological effects, where however, this i.v. route still discount future patient compliance. As druggability of DB1 in oral administration has yet to be elaborated, the current study intended to systemically investigate its biopharmaceutical properties, so as to further consider clinical applicability of DB1 oral preparations. Additionally, pharmacokinetics and pharmacodynamics of DB1 via oral administered route were also studied, illustrating broad potential of further DB1 medicine development. After the derivation, aqueous solubility of DB1 improved 3∼400 folds compared with NBP in various pH media, and n-octanol/water partition coefficient kept in the range of 0∼2. In situ single-pass intestinal perfusion on rats showed effective permeability coefficient of DB1 over 10^-2 cm/s. In contrast to NBP, oral administration of DB1 could display significant enhanced bioavailability in rats and achieve increased accumulation in brain tissues. As expected, DB1 effectively alleviated oxidative stress damage and reduced infarct volume on ischemia/reperfusion (I/R) modeled rats, resulting in reduced mortality. Additionally, this new prodrug did not add any safety concerns based on NBP. Therefore, biopharmaceutical results and preclinical pharmacodynamic evidences support the conclusion that an oral administration of DB1 may have a good potential for clinical IS treatment.

Exosomes in pathogenesis, diagnosis, and therapy of ischemic stroke

Ischemic stroke is one of the major contributors to death and disability worldwide. Thus, there is an urgent need to develop early brain tissue perfusion therapies following acute stroke and to enhance functional recovery in stroke survivors. The morbidity, therapy, and recovery processes are highly orchestrated interactions involving the brain with other tissues. Exosomes are natural and ideal mediators of intercellular information transfer and recognized as biomarkers for disease diagnosis and prognosis. Changes in exosome contents express throughout the physiological process. Accumulating evidence demonstrates the use of exosomes in exploring unknown cellular and molecular mechanisms of intercellular communication and organ homeostasis and indicates their potential role in ischemic stroke. Inspired by the unique properties of exosomes, this review focuses on the communication, diagnosis, and therapeutic role of various derived exosomes, and their development and challenges for the treatment of cerebral ischemic stroke.

Inappropriate Activation of TLR4/NF-κB is a Cause of Heart Failure

Significance: Heart failure, a disease with extremely high incidence, is closely associated with inflammation and oxidative stress. The Toll-like receptor 4 (TLR4)/nuclear factor kappa-B (NF-κB) pathway plays an important role in the occurrence and development of heart failure.

Recent advances: Previous studies have shown that TLR4/NF-κB causes heart failure by inducing oxidative stress and inflammation; damaging the endothelia; promoting fibrosis; and inducing myocardial hypertrophy, apoptosis, pyroptosis, and autophagy.

Critical issues: Understanding the pathogenesis of heart failure is essential for the treatment of this disease. In this review, we outline the mechanisms underlying TLR4/NF-κB pathway-mediated heart failure and discuss drugs that alleviate heart failure by regulating the TLR4/NF-κB pathway.

Future directions: During TLR4/NF-κB overactivation, interventions targeting specific receptor antagonists may effectively alleviate heart failure, thus providing a basis for the development of new anti-heart failure drugs.

Research progress on the role of hormones in ischemic stroke

Ischemic stroke is a major cause of death and disability around the world. However, ischemic stroke treatment is currently limited, with a narrow therapeutic window and unsatisfactory post-treatment outcomes. Therefore, it is critical to investigate the pathophysiological mechanisms following ischemic stroke brain injury. Changes in the immunometabolism and endocrine system after ischemic stroke are important in understanding the pathophysiological mechanisms of cerebral ischemic injury. Hormones are biologically active substances produced by endocrine glands or endocrine cells that play an important role in the organism's growth, development, metabolism, reproduction, and aging. Hormone research in ischemic stroke has made very promising progress. Hormone levels fluctuate during an ischemic stroke. Hormones regulate neuronal plasticity, promote neurotrophic factor formation, reduce cell death, apoptosis, inflammation, excitotoxicity, oxidative and nitrative stress, and brain edema in ischemic stroke. In recent years, many studies have been done on the role of thyroid hormone, growth hormone, testosterone, prolactin, oxytocin, glucocorticoid, parathyroid hormone, and dopamine in ischemic stroke, but comprehensive reviews are scarce. This review focuses on the role of hormones in the pathophysiology of ischemic stroke and discusses the mechanisms involved, intending to provide a reference value for ischemic stroke treatment and prevention.

Effects and Mechanisms of Exosomes from Different Sources in Cerebral Ischemia

Cerebral ischemia refers to the symptom of insufficient blood supply to the brain. Cells of many different origins participate in the process of repairing damage after cerebral ischemia occurs, in which exosomes secreted by the cells play important roles. For their characteristics, such as small molecular weight, low immunogenicity, and the easy penetration of the blood-brain barrier (BBB), exosomes can mediate cell-to-cell communication under pathophysiological conditions. In cerebral ischemia, exosomes can reduce neuronal damage and improve the brain microenvironment by regulating inflammation, mediating pyroptosis, promoting axonal growth, and stimulating vascular remodeling. Therefore, exosomes have an excellent application prospect for the treatment of cerebral ischemia. This article reviews the roles and mechanisms of exosomes from different sources in cerebral ischemia and provides new ideas for the prevention and treatment of cerebral ischemia.

Anti-PANoptosis is involved in neuroprotective effects of melatonin in acute ocular hypertension model

Acute ocular hypertension (AOH) is the most important characteristic of acute glaucoma, which can lead to retinal ganglion cell (RGC) death and permanent vision loss. So far, approved effective therapy is still lacking in acute glaucoma. PANoptosis (pyroptosis, apoptosis, and necroptosis), which consists of three key modes of programmed cell death-apoptosis, necroptosis, and pyroptosis-may contribute to AOH-induced RGC death. Previous studies have demonstrated that melatonin (N-acetyl-5-methoxytryptamine) exerts a neuroprotective effect in many retinal degenerative diseases. However, whether melatonin is anti-PANoptotic and neuroprotective in the progression of acute glaucoma remains unclear. Thus, this study aimed to explore the role of melatonin in AOH retinas and its underlying mechanisms. The results showed that melatonin treatment attenuated the loss of ganglion cell complex thickness, retinal nerve fiber layer thickness, and RGC after AOH injury, and improved the amplitudes of a-wave, b-wave, and oscillatory potentials in the electroretinogram. Additionally, the number of terminal deoxynucleotidyl transferase dUTP nick-end labeling-positive cells was decreased, and the upregulation of cleaved caspase-8, cleaved caspase-3, Bax, and Bad and downregulation of Bcl-2 and p-Bad were inhibited after melatonin administration. Meanwhile, both the expression and activation of MLKL, RIP1, and RIP3, along with the number of PI-positive cells, were reduced in melatonin-treated mice, and p-RIP3 was in both RGC and microglia/macrophage after AOH injury. Furthermore, melatonin reduced the expression of NLRP3, ASC, cleaved caspase-1, gasdermin D (GSDMD), and cleaved GSDMD, and decreased the number of Iba1/interleukin-1β-positive cells. In conclusion, melatonin ameliorated retinal structure, prevented retinal dysfunction after AOH, and exerted a neuroprotective effect via inhibition of PANoptosis in AOH retinas.

Serum MicroRNAs Predict Isolated Rapid Eye Movement Sleep Behavior Disorder and Lewy Body Diseases

BACKGROUND

Isolated rapid eye movement sleep behavior disorder (IRBD) is a well-established clinical risk factor for Lewy body diseases (LBDs), such as Parkinson's disease (PD) and dementia with Lewy bodies (DLB).

OBJECTIVE

To elucidate whether serum microRNA (miRNA) deregulation in IRBD can antedate the diagnosis of LBD by performing a longitudinal study in different progression stages of IRBD before and after LBD diagnosis and assessing the predictive performance of differentially expressed miRNAs by machine learning-based modeling.

METHODS

Using genome-wide miRNA analysis and real-time quantitative polymerase chain reaction validation, we assessed serum miRNA profiles from patients with IRBD stratified by dopamine transporter (DaT) single-photon emission computed tomography into DaT-negative IRBD (n = 17) and DaT-positive IRBD (n = 21), IRBD phenoconverted into LBD (n = 13), and controls (n = 20). Longitudinally, we followed up the IRBD cohort by studying three time point serum samples over 26 months.

RESULTS

We found sustained cross-sectional and longitudinal deregulation of 12 miRNAs across the RBD continuum, including DaT-negative IRBD, DaT-positive IRBD, and LBD phenoconverted IRBD (let-7c-5p, miR-19b-3p, miR-140, miR-22-3p, miR-221-3p, miR-24-3p, miR-25-3p, miR-29c-3p, miR-361-5p, miR-425-5p, miR-4505, and miR-451a) (false discovery rate P < 0.05). Age- and sex-adjusted predictive modeling based on the 12 differentially expressed miRNA biosignatures discriminated IRBD and PD or DLB from controls with an area under the curve of 98% (95% confidence interval: 89-99%).

CONCLUSIONS

Besides clinical diagnosis of IRBD or imaging markers such as DaT single-photon emission computed tomography, specific miRNA biosignatures alone hold promise as progression biomarkers for patients with IRBD for predicting PD and DLB clinical outcomes. Further miRNA studies in other PD at-risk populations, such as LRRK2 mutation asymptomatic carriers or hyposmic subjects, are warranted. © 2022 The Authors. Movement Disorders published by Wiley Periodicals LLC on behalf of International Parkinson and Movement Disorder Society.

Neuroprotective Effect of Corosolic Acid Against Cerebral Ischemia-Reperfusion Injury in Experimental Rats

Several therapeutic approaches were also urgently needed as ischaemic stroke was one of the most common brain disorders. Many phytochemicals have recently been discovered for the advancement of lead-like libraries that are concentrated on the peripheral and central nervous systems. Science does not yet understand how these drugs work, nor do they comprehend their in vivo characteristics. We investigated the potential benefits of corosolic acid (CA) in the treatment of brain injury caused by ischemia/reperfusion (I/R) in adult male Sprague-Dawley rats. Injury occurs after a 2-hour transient occlusion of the posterior cerebral artery and subsequent reperfusion (after 20 hours). Furthermore, the experiment assessed the size of the infarct, the amount of brain water present, as well as the neurofunctional conditions in rats. In the study, several markers of inflammation and cytokines associated with brain injury were measured. The Elisa kit was used in this study to measure the mRNA expression of interleukin-6 (IL-6), interleukin-10 (IL-10), interleukin 1β, TNF-α (tumor necrosis factor), cyclooxygenase-2 (COX-2), prostaglandin E2 (PGE2), and nitrous oxide (NO). The CA treatment significantly reduced brain water content, brain infarction volume, neurological scores, and Evans blue leakage (p < 0.001 and p < 0.001). Experimental rats were treated with CA after a significantly reduced level of anti-inflammatory, pro-inflammatory, and oxidative stress mediators was noted in their body tissues and serum (p < 0.001). By suppressing inflammatory responses in rats, CA demonstrated anti-inflammatory and neuroprotective properties.

Melatonin pretreatment on exosomes: Heterogeneity, therapeutic effects, and usage

The therapeutic outcomes of exosome-based therapies have greatly exceeded initial expectations in many clinically intractable diseases due to the safety, low toxicity, and immunogenicity of exosomes, but the production of the exosomes is a bottleneck for wide use. To increase the yield of the exosomes, various solutions have been tried, such as hypoxia, extracellular acidic pH, etc. With a limited number of cells or exosomes, an alternative approach has been developed to improve the efficacy of exosomes through cell pretreatment recently. Melatonin is synthesized from tryptophan and secreted in the pineal gland, presenting a protective effect in pathological conditions. As a new pretreatment method, melatonin can effectively enhance the antioxidant, anti-inflammatory, and anti-apoptotic function of exosomes in chronic kidney disease, diabetic wound healing, and ischemia-reperfusion treatments. However, the current use of melatonin pretreatment varies widely. Here, we discuss the effects of melatonin pretreatment on the heterogeneity of exosomes based on the role of melatonin and further speculate on the possible mechanisms. Finally, the therapeutic use of exosomes and the usage of melatonin pretreatment are described.

Exosome in Crosstalk between Inflammation and Angiogenesis: A Potential Therapeutic Strategy for Stroke

The endothelial dysfunction, associated with inflammation and vascular permeability, remains the key event in the pathogenesis of cerebral ischemic stroke. Angiogenesis is essential for neuroprotection and neural repair following stroke. The neuroinflammatory reaction plays a vital role in stroke, and inhibition of inflammation contributes to establishing an appropriate external environment for angiogenesis. Exosomes are the heterogeneous population of extracellular vesicles which play critical roles in intercellular communication through transmitting various proteins and nucleic acids to nearby and distant recipient cells by body fluids and circulation. Recent reports have shown that exosomal therapy is a valuable and potential treatment strategy for stroke. In this review, we discussed the exosomes in complex interaction mechanisms of angiogenesis and inflammation following stroke as well as the challenges of exosomal studies such as secretion, uptake, modification, and application.

Storax Protected Primary Cortical Neurons from Oxygen-Glucose Deprivation/Reoxygenation Injury via Inhibiting the TLR4/TRAF6/NF-κB Signaling Pathway

Storax is a traditional Chinese herb that is widely applied in stroke treatment. However, its neuroprotective effects and mechanisms are yet to be fully elucidated. This study aimed to elucidate the neuroprotective effects and underlying mechanisms of storax on oxygen-glucose deprivation/reoxygenation (OGD/R) in injured cortical neurons. The cortical neurons of Wistar rats were primarily cultured in vitro. TheTUNELmethod and CM-H2DCFDA probe were used to detect cell apoptosis and reactive oxygen species (ROS) expression. Enzyme-linked immunosorbent assay, reverse transcription-polymerase chain reaction, and Western blot were used to detect the expression of inflammatory cytokines and proteins of the TLR4/TRAF6/NF-κB signaling pathway. Immunofluorescence was used to measure NF-κB nuclear translocation. Transfection of TLR4 siRNA was used to detect the potential anti-inflammatory mechanisms of storax. The present results have shown that storax protected primary cortical neurons from OGD/R-induced injury by suppressing ROS generation and cell apoptosis; alleviating HMGB-1, TNF-α, IL-1β, and ICAM-1 expression; and promoting IL-10 expression. In addition, storax inhibited the activation of TLR4, TRAF6, IκBα, IKKβ, and NF-κBp65 caused by OGD/R. It is suggested that storax prevents OGD/R-induced primary cortical neuron injury by inhibiting the TLR4/TRAF6/NF-κB signaling pathway.

Microglia Pyroptosis: A Candidate Target for Neurological Diseases Treatment

In addition to its profound implications in the fight against cancer, pyroptosis have important role in the regulation of neuronal injury. Microglia are not only central members of the immune regulation of the central nervous system (CNS), but are also involved in the development and homeostatic maintenance of the nervous system. Under various pathological overstimulation, microglia pyroptosis contributes to the massive release of intracellular inflammatory mediators leading to neuroinflammation and ultimately to neuronal damages. In addition, microglia pyroptosis lead to further neurological damage by decreasing the ability to cleanse harmful substances. The pathogenic roles of microglia in a variety of CNS diseases such as neurodegenerative diseases, stroke, multiple sclerosis and depression, and many other neurological disorders have been gradually unveiled. In the context of different neurological disorders, inhibition of microglia pyroptosis by targeting NOD-like receptor family pyrin domain containing (NLRP) 3, caspase-1 and gasdermins (GSDMs) by various chemical agents as well as natural products significantly improve the symptoms or outcome in animal models. This study will provide new ideas for immunomodulatory treatment of CNS diseases.

Melatonin Alters the miRNA Transcriptome of Inflammasome Activation in Murine Microglial Cells

Systemic inflammation can have devastating effects on the central nervous system via its resident immune cells, the microglia. One of the primary mediators of this inflammation is inflammasomes, multiprotein complexes that trigger a release of inflammatory proteins when activated. Melatonin, a hormone with anti-inflammatory effects, is an attractive candidate for suppressing such inflammation. In this study, we have investigated how melatonin alters the microRNA (miRNA) transcriptome of microglial cells. For that purpose, we have performed RNA sequencing on a lipopolysaccharide and adenosine triphosphate (LPS + ATP) induced NLR family pyrin domain containing 3 (NLRP3) inflammasome activation model in the N9 mouse microglial cell line, with and without melatonin pre-treatment. We have identified 136 differentially expressed miRNAs in cells exposed to LPS + ATP compared to controls and 10 differentially expressed miRNAs in melatonin pre-treated cells compared to the inflammasome group. We have identified miR-155-3p as a miRNA that is upregulated with inflammasome activation and downregulated with melatonin treatment. We further confirmed this pattern of miR-155-3p expression in the brains of mice injected intraperitoneally with LPS. Moreover, an overexpression study with miRNA-155-3p mimic supported the idea that the protective effects of melatonin in NLRP3 inflammasome activation are partly associated with miRNA-155-3p inhibition.

Spotlight on pyroptosis: role in pathogenesis and therapeutic potential of ocular diseases

Pyroptosis is a programmed cell death characterized by swift plasma membrane disruption and subsequent release of cellular contents and pro-inflammatory mediators (cytokines), including IL‐1β and IL‐18. It differs from other types of programmed cell death such as apoptosis, autophagy, necroptosis, ferroptosis, and NETosis in terms of its morphology and mechanism. As a recently discovered form of cell death, pyroptosis has been demonstrated to be involved in the progression of multiple diseases. Recent studies have also suggested that pyroptosis is linked to various ocular diseases. In this review, we systematically summarized and discussed recent scientific discoveries of the involvement of pyroptosis in common ocular diseases, including diabetic retinopathy, age-related macular degeneration, AIDS-related human cytomegalovirus retinitis, glaucoma, dry eye disease, keratitis, uveitis, and cataract. We also organized new and emerging evidence suggesting that pyroptosis signaling pathways may be potential therapeutic targets in ocular diseases, hoping to provide a summary of overall intervention strategies and relevant multi-dimensional evaluations for various ocular diseases, as well as offer valuable ideas for further research and development from the perspective of pyroptosis.

miRNA Involvement in Cerebral Ischemia-Reperfusion Injury

Cerebral ischemia reperfusion injury is a debilitating medical condition, currently with only a limited amount of therapies aimed at protecting the cerebral parenchyma. Micro RNAs (miRNAs) are small, non-coding RNA molecules that via the RNA-induced silencing complex either degrade or prevent target messenger RNAs from being translated and thus, can modulate the synthesis of target proteins. In the neurological field, miRNAs have been evaluated as potential regulators in brain development processes and pathological events. Following ischemic hypoxic stress, the cellular and molecular events initiated dysregulate different miRNAs, responsible for long-terming progression and extension of neuronal damage. Because of their ability to regulate the synthesis of target proteins, miRNAs emerge as a possible therapeutic strategy in limiting the neuronal damage following a cerebral ischemic event. This review aims to summarize the recent literature evidence of the miRNAs involved in signaling and modulating cerebral ischemia-reperfusion injuries, thus pointing their potential in limiting neuronal damage and repair mechanisms. An in-depth overview of the molecular pathways involved in ischemia reperfusion injury and the involvement of specific miRNAs, could provide future perspectives in the development of neuroprotective agents targeting these specific miRNAs.

Dexmedetomidine Inhibits Gasdermin D-Induced Pyroptosis via the PI3K/AKT/GSK3β Pathway to Attenuate Neuroinflammation in Early Brain Injury After Subarachnoid Hemorrhage in Rats

Subarachnoid hemorrhage (SAH) is one kind of life-threatening stroke, which leads to severe brain damage. Pyroptosis plays a critical role in early brain injury (EBI) after SAH. Previous reports suggest that SAH-induced brain edema, cell apoptosis, and neuronal injury could be suppressed by dexmedetomidine (Dex). In this study, we used a rat model of SAH to investigate the effect of Dex on pyroptosis in EBI after SAH and to determine the mechanisms involved. Pyroptosis was found in microglia in EBI after SAH. Dex significantly alleviated microglia pyroptosis via reducing pyroptosis executioner GSDMD and inhibited the release of proinflammatory cytokines induced by SAH. Furthermore, the reduction of GSDMD by Dex was abolished by the PI3K inhibitor LY294002. In conclusion, our data demonstrated that Dex reduces microglia pyroptosis in EBI after SAH via the activation of the PI3K/AKT/GSK3β pathway.

NLRP3-Dependent Pyroptosis: A Candidate Therapeutic Target for Depression

Depression, a major public health problem, imposes a significant economic burden on society. Recent studies have gradually unveiled the important role of neuroinflammation in the pathogenesis of depression. Pyroptosis, a programmed cell death mediated by Gasdermins (GSDMs), is also considered to be an inflammatory cell death with links to inflammation. Pyroptosis has emerged as an important pathological mechanism in several neurological diseases and has been found to be involved in several neuroinflammatory-related diseases. A variety of chemical agents and natural products have been found to be capable of exerting therapeutic effects by modulating pyroptosis. Studies have shown that depression is closely associated with pyroptosis and the induced neuroinflammation of relevant brain regions, such as the hippocampus, amygdala, prefrontal cortex neurons, etc., in which the nucleotide-binding oligomerization domain-like receptor protein 3 inflammasome plays a crucial role. This article provides a timely review of recent findings on the activation and regulation of pyroptosis in relation to depression.

Neuronal Death Mechanisms and Therapeutic Strategy in Ischemic Stroke

Ischemic stroke caused by intracranial vascular occlusion has become increasingly prevalent with considerable mortality and disability, which gravely burdens the global economy. Current relatively effective clinical treatments are limited to intravenous alteplase and thrombectomy. Even so, patients still benefit little due to the short therapeutic window and the risk of ischemia/reperfusion injury. It is therefore urgent to figure out the neuronal death mechanisms following ischemic stroke in order to develop new neuroprotective strategies. Regarding the pathogenesis, multiple pathological events trigger the activation of cell death pathways. Particular attention should be devoted to excitotoxicity, oxidative stress, and inflammatory responses. Thus, in this article, we first review the principal mechanisms underlying neuronal death mediated by these significant events, such as intrinsic and extrinsic apoptosis, ferroptosis, parthanatos, pyroptosis, necroptosis, and autophagic cell death. Then, we further discuss the possibility of interventions targeting these pathological events and summarize the present pharmacological achievements.

Melatonin Alleviates Neonatal Necrotizing Enterocolitis by Repressing the Activation of the NLRP3 Inflammasome

Objective

Necrotizing enterocolitis (NEC) is one of the commonest gastrointestinal critical diseases in newborns. Several researches have proven the efficacy of melatonin (MEL) on NEC, but the latent mechanisms were ambiguous. We designed the current research to evaluate the function and mechanism of MEL on NEC in a neonatal mouse model.

Methods

The newborn mice were subjected to formula milk containing LPS and hypoxia to establish a NEC model and also intraperitoneally injected with MEL. During the experiment, all mice were closely monitored and weighed. The effect of MEL on the histopathological injury of the terminal ileum tissues, inflammation, and oxidative stress of serum in NEC mice was examined by hematoxylin-eosin (H&E) staining and ELISA. The effect of MEL on the NOD-like receptor family pyrin domain containing 3 (NLRP3) inflammasome was assessed via quantitative real-time PCR and Western blot.

Results

MEL intensified the survival rate and body weight in NEC mice. The H&E staining illustrated that MEL improved the histopathological injury in NEC mice. Moreover, MEL repressed the IL-1β, TNF-α, and MDA levels of serum and enhanced the SOD and GSH-Px levels of serum in NEC mice. We also discovered that MEL attenuated the mRNA and protein levels of NLRP3, Toll-like Receptor 4 (TLR4), NF-κB, and caspase-1 of the terminal ileum tissues in NEC mice.

Conclusion

Our research illuminated that MEL attenuated the severity of NEC via weakening the activation of the NLRP3 inflammasome.

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.

Exosomal miR-152-5p and miR-3681-5p function as potential biomarkers for ST-segment elevation myocardial infarction

BACKGROUND

The strain parameters of Real-Time Three-Dimensional Spot Tracking Echocardiography (RT3D-STE) are GLS, GAS, GRS, and GCS, while each index can significantly diagnose Acute Myocardial Infarction (AMI) patients, but none of them can distinguish between NSTEMI and STEMI. MicroRNAs (miRNAs) play essential roles in Acute Myocardial Infarction (AMI), but little is known about the value of exosome miRNA combined with Real-Time Three-Dimensional Spot Tracking Echocardiography (RT3D-STE) between ST-segment Elevation Myocardial Infarction (STEMI) and Non-ST-segment Elevation Myocardial Infarction (NSTEMI).

AIM

To estimate the exosomal miRNAs related to strain parameters of RT3D-STE as biomarkers for early detection of STEMI and NSTEMI.

METHODS

The present study collected plasma samples from thirty-four (34) patients with AMI (including STEMI and NSTEMI) and employed high-throughput sequence technology and real-time quantitative polymerase chain reaction (RT-qPCR) to identify the differentially expressed miRNAs. The Pearson correlation coefficient is used to measure the strength of a linear association between differentially expressed miRNAs and strain parameters of RT3D-STE.

RESULTS

Twenty-eight (28) differentially expressed exosomal miRNAs were universally identified between STEMI, NSTEM, and normal groups. Among them, there are 10 miRNAs (miR-152-5p, miR-3681-5p, miR-193a-5p, miR-193b-5p miR-345-5p, miR-125a-5p, miR-365a-3p, miR-4520-2-3p, hsa-miR-193b-3p and hsa-miR-5579-5p) with a Pearson correlation greater than 0.6 with RT3D-STE strain parameters. Especially, miR-152-5p and miR-3681-5p showed the most significant correlation with RT3D-STE strain parameters. Target genes of these 10 miRNAs are analyzed for Gene Ontology (GO) and Kyoto Encyclopedia of Genes and Genomes (KEGG) pathways enrichment, and they were found to be mainly involved in the cellular metabolism processes and HIF-1 signaling pathway. RT-qPCR verified the significant differential expression of miR-152-5p and miR-3681-5p between STEMI and NSTEM groups.

CONCLUSION

RT3D-STE and exosome miRNAs can be used as a hierarchical diagnostic system in AMI. If the RT3D-STE is abnormal, the exosome miRNAs can be detected again to obtain more detailed and accurate diagnostic results between STEMI and NSTEM groups. Exosomal miR-152-5p and miR-3681-5p may serve as potential biomarkers for ST-segment elevation myocardial infarction.

Extracellular vesicles derived from melatonin-preconditioned mesenchymal stem cells containing USP29 repair traumatic spinal cord injury by stabilizing NRF2

Spinal cord injury (SCI) is a devastating trauma that leads to irreversible motor and sensory dysfunction and is, so far, without effective treatment. Recently, however, nano-sized extracellular vesicles derived from preconditioned mesenchymal stem cells (MSCs) have shown great promise in treating various diseases, including SCI. In this study, we investigated whether extracellular vesicles (MEVs) derived from MSCs pretreated with melatonin (MT), which is well recognized to be useful in treating diseases, including Alzheimer's disease, non-small cell lung cancer, acute ischemia-reperfusion liver injury, chronic kidney disease, and SCI, are better able to promote functional recovery in mice after SCI than extracellular vesicles derived from MSCs without preconditioning (EVs). MEVs were found to facilitate motor behavioral recovery more than EVs and to increase microglia/macrophages polarization from M1-like to M2-like in mice. Experiments in BV2 microglia and RAW264.7 macrophages confirmed that MEVs facilitate M2-like polarization and also showed that they reduce the production of reactive oxygen species (ROS) and regulate mitochondrial function. Proteomics analysis revealed that ubiquitin-specific protease 29 (USP29) was markedly increased in MEVs, and knockdown of USP29 in MEVs (shUSP29-MEVs) abolished MEVs-mediated benefits in vitro and in vivo. We then showed that USP29 interacts with, deubiquitinates and therefore stabilizes nuclear factor-like 2 (NRF2), thereby regulating microglia/macrophages polarization. In NRF2 knockout mice, MEVs failed to promote functional recovery and M2-like microglia/macrophages polarization. We also showed that MT reduced global N6-methyladenosine (m⁶ A) modification and levels of the m⁶ A "writer" methyltransferase-like 3 (METTL3). The stability of USP29 mRNA in MSCs was enhanced by treatment with MT, but inhibited by overexpression of METTL3. This study describes a very promising extracellular vesicle-based approach for treating SCI.