Overexpression of SIRT1 Induced by Resveratrol and Inhibitor of miR-204 Suppresses Activation and Proliferation of Microglia

Whole Transcriptome RNA-Seq Reveals Drivers of Pathological Dysfunction in a Transgenic Model of Alzheimer's Disease

Alzheimer's disease (AD) affects more than 55 million people worldwide, yet current theories cannot fully explain its aetiology. Accordingly, gene expression profiling has been used to provide a holistic view of the biology underpinning AD. Focusing primarily on protein-coding genes, such approaches have highlighted a critical involvement of microglia-related inflammatory processes. Simultaneous investigation of transcriptional regulators and noncoding RNA (ncRNA) can offer further insight into AD biology and inform the development of disease-modifying therapies. We previously described a method for whole transcriptome sampling to simultaneously investigate protein-coding genes and ncRNA. Here, we use this technique to explore transcriptional changes in a murine model of AD (15-month-old APP/PS1 mice). We confirmed the extensive involvement of microglia-associated genes and gene networks, consistent with literature. We also report a wealth of differentially-expressed non-coding RNA - including microRNA, long non-coding RNA, small nuclear and small nucleolar RNA, and pseudogenes - many of which have been overlooked previously. Transcription factor analysis determined that six transcription factors likely regulate gene expression changes in this model (Irf8, Junb, c-Fos, Lmo2, Runx1, and Nfe2l2). We then utilised validated miRNA-target interactions, finding 60 interactions between 15 miRNA and 42 mRNA (messenger RNA) with largely consistent directionality. Furthermore, we found that eight transcription factors (Clock, Lmo2, Runx1, Nfe2l2, Egr2, c-Fos, Junb, and Nr4a1) are likely responsible for the regulation of miRNA expression. Taken together, these data indicate a complex interplay of coding and non-coding RNA, driven by a small number of specific transcription factors, contributing to transcriptional changes in 15-month-old APP/PS1 mice.

Therapeutic potential and microRNA regulating properties of phytochemicals in Alzheimer's disease

Alzheimer's disease (AD) is the leading cause of dementia in the elderly and is characterized by the aggregation of Aβ (peptide) and neurofibrillary tangles along with inflammatory processes. Aging is a significant driver of these alterations, and dementia is a major cause of disability and mortality. Despite extensive clinical trials over the past two decades, no effective drug has been developed to improve AD symptoms or slow its progression, indicating the inefficiency of current treatment targets. In AD development, the molecular microenvironment plays a significant role. MicroRNAs (miRNAs) are a key component of this microenvironment, regulate post-transcriptional gene expression, and are expressed more abundantly in the brain than in other tissues. Several dysregulated miRNAs in AD have been linked to neuropathological changes, such as plaque and tangle accrual, as well as altered expression of notorious molecules. Preclinical studies have confirmed the efficacy of phytochemicals/food bioactive compounds (PCs/FBCs) in regulating miRNA expression, which makes them immensely beneficial for targeting miRNA-altered expression patterns in neuronal diseases. This review highlights the potential of miRNAs in driving AD pathology and its development. Furthermore, it discusses the therapeutic efficacy of PCs/FBCs and their miRNA-regulatory properties, especially focusing on antiinflammatory and antioxidant capacities for their development as effective AD agents.

Flavonoids as Natural Anti-Inflammatory Agents in the Atopic Dermatitis Treatment

Eczema is a complex autoimmune condition characterised mainly by inflammation and skin lesions along with physical and psychological comorbidities. Although there have been significant advances in understanding the mechanisms behind atopic dermatitis, conventionally available treatments yield inconsistent results and have some unintended consequences. In today's digital age, where knowledge is just a click away, natural-based supplements have been on the rise for a more "natural" treatment towards any type of disease. Natural compounds, particularly derived from medicinal plants, have piqued significant interest in the development of herbal remedies for chronic inflammatory skin conditions. Among many compounds, flavonoids have shown promise in treating eczema due to their strong anti-inflammatory, antioxidant, and anti-allergic properties, making them helpful in preventing allergic reactions, inflammation, and skin irritation. This review highlights the therapeutic potential of flavonoid-based bioactive compounds to manage eczema, emphasising the mechanisms of action. Additionally, providing a comprehensive analysis of the potential of emerging and established compounds, while bridging a gap between traditional and modern medicine. Flavonoids offer a variety of opportunities for further research and innovative formulations that can maximise its full benefits. Further combination of flavonoids with various approaches such as nanoencapsulation for enhanced bioavailability, hydrogel-based delivery systems for a controlled release, and additive manufacturing for personalised topical formulations, could align with future precision medicine needs.

3-Methyladenine attenuates neuroinflammation and improves cognitive function in sepsis-associated encephalopathy by inhibiting autophagy

OBJECTIVE

Sepsis-associated encephalopathy (SAE) can lead to severe cerebral dysfunction as well as cognitive dysfunction, resulting in a significant disease burden. 3-Methyladenine (3-MA) has been confirmed to have anti-inflammatory effects on diseases characterized by enhanced autophagy. However, its role in SAE has not been clarified.

METHODS

An SAE mouse model was generated by intraperitoneal injection of lipopolysaccharide (LPS). Mice were given 5, 20, or 80 mg/kg 3-MA to determine the therapeutic dose. The mice in the different groups were given 20 mg/kg 3-MA or saline, and survival, body temperature, body weight and neurobehavioral scores were measured at different time points. The expression of autophagy-related proteins and inflammatory factors was detected by Western blotting, enzyme linked immunosorbent assay (ELISA) and real-time quantitative polymerase chain reaction (RT-qPCR) 12 h after LPS induction. Glial activation and neuronal injury in the hippocampus were detected by immunofluorescence staining and HE staining. The open Field test, novel object recognition (NOR) test, Y-maze test, and Morris water maze (MWM) test were performed to assess cognitive function.

RESULTS

Treatment with 20 or 80 mg/kg 3-MA reduced the increase in hippocampal TNF-α, IL-6, and IL-1β expression in SAE model mice, with 20 mg/kg 3-MA having the greatest therapeutic effect. Treatment with 20 mg/kg 3-MA effectively reduced the expression of hippocampal autophagy-related proteins and mortality, ameliorated hypothermia, decreased body weight and electroencephalography (EEG) performance, and attenuated the activation of neuroglia and neuronal damage. Moreover, it alleviated the cognitive dysfunction 2 weeks after LPS induction.

CONCLUSIONS

3-MA reduced neuroglial activation and neuronal damage, attenuated neuroinflammation, and improved cognitive deficits during recovery period by inhibiting autophagy in SAE.

Exploration of lncRNA/circRNA-miRNA-mRNA network in patients with chronic atrophic gastritis in Tibetan plateau areas based on DNBSEQ-G99 RNA sequencing

A higher incidence of chronic atrophic gastritis (CAG) is generally considered as a precancerous lesion in gastric cancer (GC). The aim of this study was to identify potential molecules involved in the pathogenesis of CAG in the Tibetan plateau, hoping to help the diagnosis and management of the disease. Atrophic and non-atrophic gastric mucosal tissue samples were collected from seven patients with chronic gastritis (CG). Differentially expressed lncRNAs, circRNAs, miRNAs, and mRNAs between CAG and chronic non-atrophic gastritis (CNAG) groups were identified based on DNBSEQ-G99 RNA sequencing. Subsequently, competitive endogenous RNA (ceRNA) regulatory networks (lncRNA/circRNA-miRNA-mRNA networks) were constructed. Two datasets (GSE153224 and GSE163416), involving data from non-Tibetan plateau areas, were used to further screen out Tibetan plateau key mRNAs, followed by the common genes of Tibetan plateau key and ferroptosis-related mRNAs were also identified. Functional enrichment analyses were performed to investigate the biological functions of Tibetan plateau mRNAs in the CAG. A total of seven lncRNA-miRNA-mRNA relationship pairs and 424 circRNA-miRNA-mRNA relationship pairs were identified in this study. The relationship pairs of hsa_circ_0082984-hsa-miR-204-5p-CACNG8, lncRNA DRAIC/has_circ_0008561-hsa-miR-34a-5p-AR/GXYLT2, lncRNA GAS1RR/RGMB-AS1/hsa_circ_0008561-hsa-miR-3614-5p-TMEM216/SUSD5, and LINC00941/hsa_circ_0082984-hsa-miR-873-3p-TMC5 can be involved in the pathogenesis of CAG. Additionally, eight common genes of Tibetan plateau key and ferroptosis-related differentially expressed mRNAs (DEmRNAs) (CBS, SLC2A4, STAT3, ALOX15B, ATF3, IDO1, NOX4, and SOCS1) were identified in CAG. The common genes of Tibetan plateau key and ferroptosis-related DEmRNAs can play a role in the JAK-STAT signaling pathway. This study identified important molecular biomarkers that may be involved in regulating the pathological mechanisms of CAG in the Tibetan plateau, which provides potential research directions for future research.

ROLE OF MICROGLIA IN SEPSIS-ASSOCIATED ENCEPHALOPATHY PATHOGENESIS: AN UPDATE

ABSTRACT

Sepsis-associated encephalopathy (SAE) is a serious complication of sepsis, which is characterized by cognitive dysfunction, a poor prognosis, and high incidences of morbidity and mortality. Substantial levels of systemic inflammatory factors induce neuroinflammatory responses during sepsis, ultimately disrupting the central nervous system's (CNS) homeostasis. This disruption results in brain dysfunction through various underlying mechanisms, contributing further to SAE's development. Microglia, the most important macrophage in the CNS, can induce neuroinflammatory responses, brain tissue injury, and neuronal dysregulation, resulting in brain dysfunction. They serve an important regulatory role in CNS homeostasis and can be activated through multiple pathways. Consequently, activated microglia are involved in several pathogenic mechanisms related to SAE and play a crucial role in its development. This article discusses the role of microglia in neuroinflammation, dysfunction of neurotransmitters, disruption of the blood-brain barrier, abnormal control of cerebral blood flow, mitochondrial dysfunction, and reduction in the number of good bacteria in the gut as main pathogenic mechanisms of SAE and focuses on studies targeting microglia to ameliorate SAE to provide a theoretical basis for targeted microglial therapy for SAE.

Dexmedetomidine mitigates neuroinflammation in an Alzheimer's disease mouse model via the miR-204-3p/FBXL7 signaling axis

Alzheimer's disease (AD) is a prevalent neurodegenerative disorder characterized by neuroinflammation. Dexmedetomidine (Dex) is known for its neuroprotective properties in clinical settings. In this study, we investigated the potential of Dex in protecting against neuroinflammation in an AD mouse model induced by amyloid-beta (Aβ) injection. First, in the AD mouse model, Aβ injection were administered, and the model was confirmed through behavioral tests, including the Morris water maze and Y-maze. Neuroinflammatory states in Aβ-injected mice were assessed using hematoxylin and eosin staining and enzyme-linked immunosorbent assay. Expression levels of microRNA (miR)-204-3p and F-box/LRR-repeat protein 7 (FBXL7) in mouse tissues were determined through real-time quantitative polymerase chain reaction and Western blot. The binding interaction between miR-204-3p and FBXL7 was elucidated using dual-luciferase analysis. Aβ-injected mice exhibited cognitive impairment, neuroinflammation, and downregulated miR-204-3p. Upregulation of miR-204-3p reduced inflammatory infiltration and mitigated neuroinflammation in Aβ-injected mice. Dex treatment reduced inflammation in hippocampal tissues of Aβ-injected mice. Dex treatment upregulated miR-204-3p, leading to suppressed FBXL7 expression in tissues. Inhibition of miR-204-3p or overexpression of FBXL7 reversed the alleviating effect of Dex on neuroinflammation in Aβ-injected mice. Overall, Dex increased miR-204-3p expression, resulting in the inhibition of FBXL7, and subsequently alleviated neuroinflammation in Aβ-injected mice.

Molecular Mechanism of SOX18 in Lipopolysaccharide-Induced Injury of Human Umbilical Vein Endothelial Cells

Endothelial dysfunction is associated with the progression of sepsis. This study sought to probe the molecular route of sex-determining region on the Y chromosome-box transcription factor 18 (SOX18) in sepsis-associated endothelial injury. Human umbilical vein endothelial cells (HUVECs) were treated with lipopolysaccharide (LPS) to establish the sepsis cell model. Cell viability, lactate dehydrogenase (LDH) release, oxidative stress (reactive oxygen species/malondialdehyde/superoxide dismutase), and inflammation (interleukin-1β/tumor necrosis factor-α/interleukin-6) were evaluated by cell counting kit-8 assay and relevant assay kits. The expression levels of SOX18, microRNA (miR)-204-5p, and cadherin-2 (CDH2) in cells were determined by real-time quantitative polymerase chain reaction and Western blot assay. The interaction of SOX18, miR-204-5p, and CDH2 was analyzed by chromatin immunoprecipitation and dual-luciferase assay. LPS induced HUVECs injury and downregulation of SOX18. SOX18 overexpression increased cell viability, while decreased LDH activity, oxidative stress, and inflammation. SOX18 bound to the miR-204-5p promoter to promote miR-204-5p expression, and further repressed CDH2 expression. miR-204-5p knockdown and CDH2 overexpression abrogated the protective role of SOX18 in HUVECs injury. Overall, SOX18 alleviated LPS-induced injury of HUVECs by promoting miR-204-5p and repressing CDH2, suggesting it as a potential target for sepsis treatment.

Non-Coding RNA in Microglia Activation and Neuroinflammation in Alzheimer's Disease

Alzheimer's disease (AD) is a neurodegenerative disorder characterized by complex pathophysiological features. Amyloid plaques resulting from extracellular amyloid deposition and neurofibrillary tangles formed by intracellular hyperphosphorylated tau accumulation serve as primary neuropathological criteria for AD diagnosis. The activation of microglia has been closely associated with these pathological manifestations. Non-coding RNA (ncRNA), a versatile molecule involved in various cellular functions such as genetic information storage and transport, as well as catalysis of biochemical reactions, plays a crucial role in microglial activation. This review aims to investigate the regulatory role of ncRNAs in protein expression by directly targeting genes, proteins, and interactions. Furthermore, it explores the ability of ncRNAs to modulate inflammatory pathways, influence the expression of inflammatory factors, and regulate microglia activation, all of which contribute to neuroinflammation and AD. However, there are still significant controversies surrounding microglial activation and polarization. The categorization into M1 and M2 phenotypes may oversimplify the intricate and multifaceted regulatory processes in microglial response to neuroinflammation. Limited research has been conducted on the role of ncRNAs in regulating microglial activation and inducing distinct polarization states in the context of neuroinflammation. Moreover, the regulatory mechanisms through which ncRNAs govern microglial function continue to be refined. The current understanding of ncRNA regulatory pathways involved in microglial activation remains incomplete and may be influenced by spatial, temporal, and tissue-specific factors. Therefore, further in-depth investigations are warranted. In conclusion, there are ongoing debates and uncertainties regarding the activation and polarization of microglial cells, particularly concerning the categorization into M1 and M2 phenotypes. The study of ncRNA regulation in microglial activation and polarization, as well as its mechanisms, is still in its early stages and requires further investigation. However, this review offers new insights and opportunities for therapeutic approaches in AD. The development of ncRNA-based drugs may hold promise as a new direction in AD treatment.

A comprehensive insight into the molecular and cellular mechanisms of action of resveratrol on complications of sepsis a systematic review

Sepsis and septic shock are still one of the most important medical challenges. Sepsis is an extreme and uncontrolled response of the innate immune system to invading pathogenesis. Resveratrol (3,5,4'-trihydroxytrans-stilbene), is a phenolic and non-flavonoid compound naturally produced by some plants and fruits. The object of the current study is to systematically review the impacts of resveratrol and its mechanisms of function in the management of sepsis and its related complications. The guidelines of the Preferred Reporting Items for Systematic Review and Meta-Analysis (PRISMA) statements were applied to perform the study (PROSPERO: CRD42021289357). We searched Embase, Web of Science, Google Scholar, Science Direct, PubMed, ProQuest, and Scopus databases up to January 2023 by using the relevant keywords. Study criteria were met by 72 out of 1415 articles screened. The results of this systematic review depict that resveratrol can reduces the complications of sepsis by affecting inflammatory pathways, oxidative stress, and modulating immune responses. Future human randomized clinical trials are necessary due to the promising therapeutic effects of resveratrol on sepsis complications and the lack of clinical trials in this regard.

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.

Immune Regulatory Functions of Macrophages and Microglia in Central Nervous System Diseases

Macrophages can be characterized as a very multifunctional cell type with a spectrum of phenotypes and functions being observed spatially and temporally in various disease states. Ample studies have now demonstrated a possible causal link between macrophage activation and the development of autoimmune disorders. How these cells may be contributing to the adaptive immune response and potentially perpetuating the progression of neurodegenerative diseases and neural injuries is not fully understood. Within this review, we hope to illustrate the role that macrophages and microglia play as initiators of adaptive immune response in various CNS diseases by offering evidence of: (1) the types of immune responses and the processes of antigen presentation in each disease, (2) receptors involved in macrophage/microglial phagocytosis of disease-related cell debris or molecules, and, finally, (3) the implications of macrophages/microglia on the pathogenesis of the diseases.

Anti-Inflammatory Therapeutic Mechanisms of Natural Products: Insight from Rosemary Diterpenes, Carnosic Acid and Carnosol

Carnosic acid (CA) and carnosol (CAR) are two major diterpenes of the rosemary plant (Rosmarinus officinalis). They possess a phenolic structural moiety and are endowed with the power to remove cellular reactive oxygen species (ROS) either through direct scavenging reaction or indirectly through upregulation of antioxidant defences. Hand in hand with these activities are their multiple biological effects and therapeutic potential orchestrated through modulating various signalling pathways of inflammation, including the NF-κB, MAPK, Nrf2, SIRT1, STAT3 and NLRP3 inflammasomes, among others. Consequently, they ameliorate the expression of pro-inflammatory cytokines (e.g., TNF-α, IL-1 and IL-6), adhesion molecules, chemokines and prostaglandins. These anti-inflammatory mechanisms of action as a therapeutic link to various effects of these compounds, as in many other natural products, are scrutinised.

Sirt1 regulates microglial activation and inflammation following oxygen-glucose deprivation/reoxygenation injury by targeting the Shh/Gli-1 signaling pathway

BACKGROUND

Cerebral ischemic injury leads to over-activation of microglia, which release pro-inflammatory factors that deteriorate neurological function during the acute phase of stroke. Thus, inhibiting microglial over-activation is crucial for reducing ischemic injury. Sirtuin 1 (Sirt1) has been shown to play a critical role in stroke, neurodegenerative diseases and aging. However, the effect of Sirt1 on the regulation of microglial activation following cerebral ischemic injury, as well as the underlying mechanism, remain unknown. Therefore, the purpose of the present study is to mainly investigate the effect of Sirt1 on oxygen-glucose deprivation/reoxygenation (OGD/R)-treated N9 microglia following treatment with the Sirt1 agonists resveratrol and SRT1720 and the Sirt1 antagonist sirtinol.

METHODS

Cell viability, Apoptosis, activation and inflammatory responses of microglia, expressions and activity of Shh signaling pathway proteins were detected by Cell Counting Kit 8, Flow Cytometry, immunocytochemistry, ELISA, and Western blotting, respectively.

RESULTS

The results demonstrated that treatment with resveratrol or SRT1720 could inhibit the activation of microglia and inflammation during OGD/R. Moreover, these treatments also led to the translocation of the GLI family zinc finger-1 (Gli-1) protein from the cytoplasm to the nucleus and upregulated the expression of Sonic hedgehog (Shh), Patched homolog-1 (Ptc-1), smoothened frizzled class receptor and Gli-1. By contrast, the inhibition of Sirt1 using sirtinol had the opposite effect.

CONCLUSION

These findings suggested that Sirt1 may regulate microglial activation and inflammation by targeting the Shh/Gli-1 signaling pathway following OGD/R injury. Schematic representation of Sirt1 regulating the microglial activation and inflammation following oxygen-glucose deprivation/reoxygenation injury via mediation of Shh/Gli-1 signaling pathway.

Microglial Activation in Metal Neurotoxicity: Impact in Neurodegenerative Diseases

Neurodegenerative processes encompass a large variety of diseases with different pathological patterns and clinical features, such as Alzheimer's and Parkinson's diseases. Exposure to metals has been hypothesized to increase oxidative stress in brain cells leading to cell death and neurodegeneration. Neurotoxicity of metals has been demonstrated by several in vitro and in vivo experimental studies, and most probably, each metal has its specific pathway to trigger cell death. As a result, exposure to essential metals, such as manganese, iron, copper, zinc, and cobalt, and nonessential metals, including lead, aluminum, and cadmium, perturbs metal homeostasis at the cellular and organism levels leading to neurodegeneration. In this contribution, a comprehensive review of the molecular mechanisms by which metals affect microglia physiology and signaling properties is presented. Furthermore, studies that validate the disruption of microglia activation pathways as an essential mechanism of metal toxicity that can contribute to neurodegenerative disease are also presented and discussed.

Knockdown of SEMA7A alleviates MPP+ -induced apoptosis and inflammation in BV2 microglia via PPAR-γ activation and MAPK inactivation

INTRODUCTION

The inflammation mediated by microglial cells plays an important role in the process of neurodegenerative diseases. Recent evidence indicates that semaphorin 7A (SEMA7A) is implicated in various neurodegenerative diseases, but whether it plays a role in Parkinson's disease (PD) remains unclear.

METHODS

In this study, 1.0 mmol/L 1-methyl-4-phenylpyridinium (MPP+ )-stimulated mouse microglia (BV2) cells were used as an in vitro model of PD. The expression of SEMA7A was detected by quantitative polymerase chain reaction. Cell Counting Kit-8 and apoptosis kits were used to analyze the viability and apoptosis of BV-2 cells. The content of IL-6, IL-β, and tumor necrosis factor-α was determined by ELISA (enzyme-linked immunosorbent assay) kit. Western blot was used to detect the protein expression level of the inducible NO synthase and cyclooxygenase-2.

RESULTS

Our findings indicated that SEMA7A expression in BV2 cells was upregulated after MPP+ stimulation. Knockdown of SEMA7A promoted cell viability while it inhibited apoptosis and the expression of proinflammatory enzymes and proinflammatory cytokines. Silencing SEMA7A-induced peroxisome proliferator-activated receptor-gamma (PPAR-γ) activation and mitogen-activated protein kinase (MAPK) signaling pathway inactivation. Furthermore, a PPAR-γ inhibitor and an MAPK activator promoted the effect of MPP+ on cell viability, apoptosis, and inflammation of BV2 cells; what is more, the PPAR-γ inhibitor and MAPK activator blocked the inhibitory effect of SEMA7A downregulation on MPP+ -induced injury.

CONCLUSION

In general, knockdown of SEMA7A inhibits MPP+ -induced BV2 cell apoptosis and inflammation via PPAR-γ activation and MAPK inactivation, which may provide a new therapy target for PD.

Central role of microglia in sepsis-associated encephalopathy: From mechanism to therapy

Sepsis-associated encephalopathy (SAE) is a cognitive impairment associated with sepsis that occurs in the absence of direct infection in the central nervous system or structural brain damage. Microglia are thought to be macrophages of the central nervous system, devouring bits of neuronal cells and dead cells in the brain. They are activated in various ways, and microglia-mediated neuroinflammation is characteristic of central nervous system diseases, including SAE. Here, we systematically described the pathogenesis of SAE and demonstrated that microglia are closely related to the occurrence and development of SAE. Furthermore, we comprehensively discussed the function and phenotype of microglia and summarized their activation mechanism and role in SAE pathogenesis. Finally, this review summarizes recent studies on treating cognitive impairment in SAE by blocking microglial activation and toxic factors produced after activation. We suggest that targeting microglial activation may be a putative treatment for SAE.

Disease-Associated Regulation of Non-Coding RNAs by Resveratrol: Molecular Insights and Therapeutic Applications

There have been significant advances, particularly over the last 20 years, in the identification of non-coding RNAs (ncRNAs) and their pathophysiological role in a wide range of disease states, particularly cancer and other chronic conditions characterized by excess inflammation and oxidative stress such as atherosclerosis, diabetes, obesity, multiple sclerosis, osteoporosis, liver and lung fibrosis. Such discoveries have potential therapeutic implications as a better understanding of the molecular mechanisms underpinning the effects of ncRNAs on critical homeostatic control mechanisms and biochemical pathways might lead to the identification of novel druggable targets. In this context, increasing evidence suggests that several natural compounds can target ncRNAs at different levels and, consequently, influence processes involved in the onset and progression of disease states. The natural phenol resveratrol has been extensively studied for therapeutic purposes in view of its established anti-inflammatory and antioxidant effects, particularly in disease states such as cancer and cardiovascular disease that are associated with human aging. However, increasing in vitro and in vivo evidence also suggests that resveratrol can directly target various ncRNAs and that this mediates, at least in part, its potential therapeutic effects. This review critically appraises the available evidence regarding the resveratrol-mediated modulation of different ncRNAs in a wide range of disease states characterized by a pro-inflammatory state and oxidative stress, the potential therapeutic applications, and future research directions.

Neuroprotective Potential of Dendritic Cells and Sirtuins in Multiple Sclerosis

Myeloid cells, including parenchymal microglia, perivascular and meningeal macrophages, and dendritic cells (DCs), are present in the central nervous system (CNS) and establish an intricate relationship with other cells, playing a crucial role both in health and in neurological diseases. In this context, DCs are critical to orchestrating the immune response linking the innate and adaptive immune systems. Under steady-state conditions, DCs patrol the CNS, sampling their local environment and acting as sentinels. During neuroinflammation, the resulting activation of DCs is a critical step that drives the inflammatory response or the resolution of inflammation with the participation of different cell types of the immune system (macrophages, mast cells, T and B lymphocytes), resident cells of the CNS and soluble factors. Although the importance of DCs is clearly recognized, their exact function in CNS disease is still debated. In this review, we will discuss modern concepts of DC biology in steady-state and during autoimmune neuroinflammation. Here, we will also address some key aspects involving DCs in CNS patrolling, highlighting the neuroprotective nature of DCs and emphasizing their therapeutic potential for the treatment of neurological conditions. Recently, inhibition of the NAD⁺-dependent deac(et)ylase sirtuin 6 was demonstrated to delay the onset of experimental autoimmune encephalomyelitis, by dampening DC trafficking towards inflamed LNs. Thus, a special focus will be dedicated to sirtuins’ role in DCs functions.

Sulforaphane Induces Glioprotection After LPS Challenge

Sulforaphane is a natural compound that presents anti-inflammatory and antioxidant properties, including in the central nervous system (CNS). Astroglial cells are involved in several functions to maintain brain homeostasis, actively participating in the inflammatory response and antioxidant defense systems. We, herein, investigated the potential mechanisms involved in the glioprotective effects of sulforaphane in the C6 astrocyte cell line, when challenged with the inflammogen, lipopolysaccharide (LPS). Sulforaphane prevented the LPS-induced increase in the expression and/or release of pro-inflammatory mediators, possibly due to nuclear factor κB and hypoxia-inducible factor-1α activation. Sulforaphane also modulated the expressions of the Toll-like and adenosine receptors, which often mediate inflammatory processes induced by LPS. Additionally, sulforaphane increased the mRNA levels of nuclear factor erythroid-derived 2-like 2 (Nrf2) and heme oxygenase-1 (HO1), both of which mediate several cytoprotective responses. Sulforaphane also prevented the increase in NADPH oxidase activity and the elevations of superoxide and 3-nitrotyrosine that were stimulated by LPS. In addition, sulforaphane and LPS modulated superoxide dismutase activity and glutathione metabolism. Interestingly, the anti-inflammatory and antioxidant effects of sulforaphane were blocked by HO1 pharmacological inhibition, suggesting its dependence on HO1 activity. Finally, in support of a glioprotective role, sulforaphane prevented the LPS-induced decrease in glutamate uptake, glutamine synthetase activity, and glial-derived neurotrophic factor (GDNF) levels, as well as the augmentations in S100B release and Na+, K+ ATPase activity. To our knowledge, this is the first study that has comprehensively explored the glioprotective effects of sulforaphane on astroglial cells, reinforcing the beneficial effects of sulforaphane on astroglial functionality.

Expression and clinical significance of miR-204 in patients with hypertensive disorder complicating pregnancy

Objective

Hypertensive disorder complicating pregnancy (HDCP) is a unique and common obstetrical complication in pregnancy. The current study sought to investigate the diagnostic value of serum miR-204 in HDCP patients.

Methods

A total of 196 HDCP patients were enrolled, with 54 healthy pregnant women as controls. The expression levels of miR-204 and inflammatory factors in the serum were determined. Receiver operating characteristic (ROC) curve was used to assess the diagnostic value of miR-204 in HDCP patients. Person coefficient was introduced to analyze the correlation between miR-204 and inflammatory indexes. Kaplan–Meier method was employed to analyze the effect of miR-204 expression on the incidence of adverse pregnancy outcomes. Logistic regression was adopted to assess the risk factors for adverse pregnancy outcomes.

Results

miR-204 expression was upregulated in the serum of HDCP patients. The serum miR-204 level > 1.432 could assist the diagnosis of HDCP. miR-204 level in the serum was positively correlated with TNF-α, IL-6, and hs-CRP concentrations in HDCP patients. The risk of adverse outcomes was higher in pregnant women with high miR-204 expression. High miR-204 expression was associated with an increased risk of adverse pregnancy outcomes after adjusting the family history of HDCP, systolic pressure, diastolic pressure, AST, ALT, LDH, 24-h urinary protein, TNF-α, IL-6, and hs-CRP.

Conclusion

The high expression of miR-204 assists the diagnosis of HDCP and is an independent risk factor for adverse pregnancy outcomes in HDCP patients.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12884-022-04501-9.

MiR-200c-3p inhibits LPS-induced M1 polarization of BV2 cells by targeting RIP2

BACKGROUND

Microglia are important immune cells, which can be induced by lipopolysaccharide (LPS) into M1 phenotype that express pro-inflammatory cytokines. Some studies have shown that microRNAs play critical roles in microglial activation.

OBJECTIVE

This study was designed to investigate the role of miR-200c-3p in regulating inflammatory responses of LPS-treated BV2 cells.

METHODS

The expression of miR-200c-3p in BV2 cells was detected by real-time PCR. Receptor-interacting protein 2 (RIP2) was predicted as a target gene of miR-200c-3p. Their relationship was verified by dual-luciferase reporter assay. The function of miR-200c-3p and RIP2 in microglial polarization and NF-κB signaling was further evaluated.

RESULTS

LPS treatment reduced miR-200c-3p expression in a dose-dependent and time-dependent manner in BV2 cells. LPS treatment increased the expression of M1 phenotype markers inducible nitric oxide synthase (iNOS) and major histocompatibility complex class (MHC)-II, promoted the release of pro-inflammatory cytokines interleukin (IL)-1β, IL-6 and tumor necrosis factor (TNF)-α, and enhanced the nuclear translocation and phosphorylation of nuclear factor-kappaB (NF-κB) p65. Reversely, miR-200c-3p mimics down-regulated the levels of these inflammatory factors. Furthermore, RIP2 was identified to be a direct target of miR-200c-3p. RIP2 knockdown had a similar effect to miR-200c-3p mimics. Overexpression of RIP2 eliminated the inhibitory effect of miR-200c-3p on LPS-induced M1 polarization and NF-κB activation in BV2 cells.

CONCLUSIONS

MiR-200c-3p mimics suppressed LPS-induced microglial M1 polarization and NF-κB activation by targeting RIP2. MiR-200c-3p/RIP2 might be a potential therapeutic target for the treatment of neuroinflammation-associated diseases.

Apple phenolic extract ameliorates lead-induced cognitive impairment, depression- and anxiety-like behavior in mice through abating oxidative stress, inflammation and apoptosis via miR-22-3p/SIRT1 axis

Lead can lead to neurotoxicity and cognitive impairment. In this study, for the first time, the protective effects and working mechanisms of apple phenolic extract (APE) against lead acetate (Pb(Ac)2)-induced...

MicroRNAs as Potential Orchestrators of Alzheimer's Disease-Related Pathologies: Insights on Current Status and Future Possibilities

Alzheimer's disease (AD) is a progressive and deleterious neurodegenerative disease, strongly affecting the cognitive functions and memory of seniors worldwide. Around 58% of the affected patients live in low and middle-income countries, with estimates of increasing deaths caused by AD in the coming decade. AD is a multifactor pathology. Mitochondrial function declines in AD brain and is currently emerging as a hallmark of this disease. It has been considered as one of the intracellular processes severely compromised in AD. Many mitochondrial parameters decline already during aging; mitochondrial efficiency for energy production, reactive oxygen species (ROS) metabolism and the de novo synthesis of pyrimidines, to reach an extensive functional failure, concomitant with the onset of neurodegenerative conditions. Besides its impact on cognitive functions, AD is characterized by loss of synapses, extracellular amyloid plaques composed of the amyloid-β peptide (Aβ), and intracellular aggregates of hyperphosphorylated Tau protein, accompanied by drastic sleep disorders, sensory function alterations and pain sensitization. Unfortunately, till date, effective management of AD-related disorders and early, non-invasive AD diagnostic markers are yet to be found. MicroRNAs (miRNAs) are small non-coding nucleic acids that regulate key signaling pathway(s) in various disease conditions. About 70% of experimentally detectable miRNAs are expressed in the brain where they regulate neurite outgrowth, dendritic spine morphology, and synaptic plasticity. Increasing studies suggest that miRNAs are intimately involved in synaptic function and specific signals during memory formation. This has been the pivotal key for considering miRNAs crucial molecules to be studied in AD. MicroRNAs dysfunctions are increasingly acknowledged as a pivotal contributor in AD via deregulating genes involved in AD pathogenesis. Moreover, miRNAs have been proved to control pain sensitization processes and regulate circadian clock system that affects the sleep process. Interestingly, the differential expression of miRNA panels implies their emerging potential as diagnostic AD biomarkers. In this review, we will present an updated analysis of miRNAs role in regulating signaling processes that are involved in AD-related pathologies. We will discuss the current challenges against wider use of miRNAs and the future promising capabilities of miRNAs as diagnostic and therapeutic means for better management of AD.

Sodium P-aminosalicylic Acid Inhibits Manganese-Induced Neuroinflammation in BV2 Microglial Cells via NLRP3-CASP1 Inflammasome Pathway

BACKGROUND

Sodium p-aminosalicylic acid (PAS-Na) was reported to exhibit anti-inflammatory effect in the nervous system. However, the mechanism by which PAS-Na exhibits anti-inflammatory effects on manganese (Mn)-stimulated BV2 microglia cells remains unclear. Thus, this study investigated the role of PAS-Na in Mn-stimulated BV2 microglial cells.

METHODS

Microglia-like BV2 were treated with MnCl₂ with or without the non-steroidal anti-inflammatory drug PAS-Na for 12 or 24 h to examine cell viability using MTT; for 24 or 48 h to examine levels of NLRP3, CASP1, IL-1β, and IL-18 mRNA using Real-Time quantitative PCR; for 48 h to examine levels of NLRP3 and CASP1 inflammasomes, measured by western blot analysis; and for 48 h to examine levels of inflammatory cytokines, measured by enzyme-linked immunosorbent assay.

RESULTS

The MTT assay showed that PAS-Na produced significant neuroprotective effect by preventing Mn-induced inflammation in BV2 microglial cells. PAS-Na significantly concentration and time dependently inhibited Mn-induced production of NLRP3, CASP1, IL-1β, and IL-18.

CONCLUSION

Taken together, our results suggest that PAS-Na exerts anti-inflammatory effects in Mn-stimulated BV2 microglial cells via downregulation of NLRP3, CASP1, IL-1β, and I L-18. Furthermore, a high concentration and prolonged PAS-Na treatment appear necessary for its therapeutic efficacy. Taken together, we conclude that PAS-Na affords therapeutic efficacy in mitigating neurological conditions associated with neuroinflammation.

Formyl Peptide Receptor (FPR)1 Modulation by Resveratrol in an LPS-Induced Neuroinflammatory Animal Model

Among therapeutic approaches that have been investigated, targeting of receptors implicated in managing neuroinflammation has been described. One such family of receptors comprises the formyl peptide receptors (FPRs) whose ligands could play a role in host defense. The murine FPR gene family includes at least six members while in humans there are only three. The two most important members are the Fpr1 and Fpr2. Fpr1encodes murine FPR1, which is considered the murine orthologue of human FPR. Resveratrol, a non-flavonoid polyphenol rich in red wine and grapes, apart from its beneficial health effects and anti-inflammatory properties, has been reported to reduce neuroinflammation in different neurodegenerative disease models. Resveratrol anti-inflammatory responses involve the activation of the protein deacetylase sirtuin 1 (SIRT1) gene. In this work we have investigated in an LPS-based murine model of neuroinflammation the role of FPR1, examining not only if this receptor undergoes a reduction of its expression during neuroinflammation, but also whether treatment with resveratrol was able to modulate its expression leading to an amelioration of neuroinflammatory picture in a murine model of neuroinflammation. Results of this work showed that FPR1 together with SIRT1 resulted upregulated by resveratrol treatment and that this increase is associated with an amelioration of the neuroinflammatory picture, as demonstrated by the induction of IL-10 and IL1-RA expression and the downregulation of proinflammatory mediators, such as TNF-α and IL-1β. The expression and the modulation of FPR1 by resveratrol may be evaluated in order to propose a novel anti-inflammatory and pro-resolving therapeutic approach for the reduction of the detrimental effects associated with neuro-inflammation based neurodegenerative diseases and also as a promising strategy to promote human health by a diet rich in antioxidative bioactive compounds.

LPS promotes the progression of sepsis by activation of lncRNA HULC/miR-204-5p/TRPM7 network in HUVECs

Sepsis is a systemic inflammatory response syndrome caused by infection. Lipopolysaccharide (LPS) has been reported to induce inflammatory responses, and long non-coding RNA highly up-regulated in liver cancer (HULC) expression was associated with the progression of sepsis. But the role and underlying mechanism of HULC in LPS-induced sepsis remain unclear. Cell viability and apoptosis were measured by methyl thiazolyl tetrazolium (MTT) and flow cytometry assays, respectively. The levels of apoptosis-related proteins, inflammatory cytokines and transient receptor potential melastatin7 (TRPM7) were detected by western blot. Reactive oxygen species (ROS), superoxide dismutase (SOD) and malondialdehyde (MDA) levels were detected by dichloro-dihydro-fluorescein diacetate (DCFH-DA) method using commercial kit. HULC, microRNA-204-5p (miR-204-5p) and TRPM7 expressions in serum of sepsis patients and human umbilical vein endothelial cells (HUVECs) were examined by quantitative real-time polymerase chain reaction (qRT-PCR). Dual-luciferase reporter and RNA immunoprecipitation (RIP) assays were used to confirm the interaction between HULC and miR-204-5p, miR-204-5p and TRPM7. LPS stimulation restrained cell viability and facilitated apoptosis, inflammatory injury and oxidative stress in HUVECs. HULC and TRPM7 were increased and accompanied with decreased miR-204-5p expression in serum of sepsis patients. A significant negative correlation between miR-204-5p and HULC or TRPM7 was observed, and there was a positive relationship between expressions of HULC and TRPM7. Importantly, LPS inhibited the cell viability and induced apoptosis, inflammatory injury and oxidative stress of HUVECs by up-regulating the expressions of HULC and TRPM7, and down-modulating miR-204-5p expression. Mechanically, HULC positively regulated TRPM7 expression by sponging miR-204-5p in HUVECs. LPS impaired cell viability, and promoted cell apoptosis, inflammatory response and oxidative stress in HUVECs by regulating HULC/miR-204-5p/TRPM7 axis.

miRNAs in Microglia: Important Players in Multiple Sclerosis Pathology

Microglia are the resident immune cells of the central nervous system and important regulators of brain homeostasis. Central to this role is a dynamic phenotypic plasticity that enables microglia to respond to environmental and pathological stimuli. Importantly, different microglial phenotypes can be both beneficial and detrimental to central nervous system health. Chronically activated inflammatory microglia are a hallmark of neurodegeneration, including the autoimmune disease multiple sclerosis (MS). By contrast, microglial phagocytosis of myelin debris is essential for resolving inflammation and promoting remyelination. As such, microglia are being explored as a potential therapeutic target for MS. MicroRNAs (miRNAs) are short non-coding ribonucleic acids that regulate gene expression and act as master regulators of cellular phenotype and function. Dysregulation of certain miRNAs can aberrantly activate and promote specific polarisation states in microglia to modulate their activity in inflammation and neurodegeneration. In addition, miRNA dysregulation is implicated in MS pathogenesis, with circulating biomarkers and lesion specific miRNAs identified as regulators of inflammation and myelination. However, the role of miRNAs in microglia that specifically contribute to MS progression are still largely unknown. miRNAs are being explored as therapeutic agents, providing an opportunity to modulate microglial function in neurodegenerative diseases such as MS. This review will focus firstly on elucidating the complex role of microglia in MS pathogenesis. Secondly, we explore the essential roles of miRNAs in microglial function. Finally, we focus on miRNAs that are implicated in microglial processes that contribute directly to MS pathology, prioritising targets that could inform novel therapeutic approaches to MS.

Neuroinflammation in Ischemic Stroke: Focus on MicroRNA-mediated Polarization of Microglia

Ischemic stroke is one of the most common causes of death and disability worldwide. Neuroinflammation is a major pathological event involved in the process of ischemic injury and repair. In particular, microglia play a dual role in neuroinflammation. During the acute phase of stroke onset, M2 microglia are the dominant phenotype and exert protective effects on neuronal cells, whereas permanent M1 microglia contribute to prolonged inflammation and are detrimental to brain tissue. Emerging evidence indicates that microRNAs (miRNAs) may have regulatory effects on microglia-associated inflammation. Thus, we briefly reviewed the dynamic response of microglia after a stroke and assessed how specific miRNAs affect the behavior of reactive microglia. We concluded that miRNAs may be useful novel therapeutic targets to improve stroke outcomes and modulate neuroinflammation.

Resveratrol inhibits ACHN cells via regulation of histone acetylation

Context: The relationship between resveratrol and histone acetylation in renal cell carcinoma (RCC) has not yet been reported.Objective: To explore the functional role of resveratrol in RCC.Materials and methods: Functional experiments were performed to determine proliferatio n of ACHN cells with treatment of resveratrol (0, 7.8125, 15.625, 31.25 and 62.5 μg/mL, for 12, 24 and 48 h of culture) or 0.1 μM SAHA. The enzyme activities of MMP-2/-9 were measured by gelatine zymography and histone acetylation by Western blot.Results: When the cells were treated with 15.625, 31.25 and 62.5 μg/mL resveratrol, ACHN cells viability was 73.2 ± 3.5%, 61.4 ± 3.1%, 50.2 ± 4.7% for 12 h, 62.7 ± 4.5%, 52.4 ± 5.5%, 40.2 ± 3.8% for 24 h, and 60.8 ± 3.7%, 39.4 ± 5.1%, 37.6 ± 2.7% for 48 h, and the wound closure (%) of migration was increased from 0.6 to 0.7, 0.85, 0.9 for 12 h and from 0.23 to 0.3, 0.48, 0.59 for 24 h. The invasion rate was 8.5 ± 0.9%, 7.4 ± 0.3% and 5.8 ± 0.6%, and cell cycle was arrested at G1 from 42.5 ± 2.9% to 55.3 ± 5.7%, 59.8 ± 3.4%, 68.7 ± 4.6%. MMP-2/-9 expression (p < 0.05) was inhibited by resveratrol. The protein levels of histone acetylation (p < 0.01) was increased by resveratrol.Discussion and conclusions: Our results suggest that these effects might be related to a high level of histone acetylation, and resveratrol can be considered as an alternative treatment for RCC.

Signaling mechanisms underlying inhibition of neuroinflammation by resveratrol in neurodegenerative diseases

Neurodegenerative diseases (NDs), including Alzheimer's disease (AD), and Parkinson's disease (PD), are characterized by the progressive loss of the structure and function of neurons and most commonly occur in the elderly population. Microglia are resident macrophages of the central nervous system (CNS). The neuroinflammation caused by excessive microglial activation is closely related to the onset and progression of many NDs. Therefore, inhibiting excessive microglial activation is a potential drug target for controlling neuroinflammation. In recent years, natural products as modulators of microglial polarization have attracted considerable attention in the field of NDs therapy. Furthermore, resveratrol (RES) has been found to have a protective effect in NDs through the inhibition of microglial activation and the regulation of neuroinflammation. In this review, we mainly summarize the therapeutic potential of RES and its various molecular mechanisms in the treatment of NDs through the modulation of microglial activation.

The Beneficial Roles of SIRT1 in Neuroinflammation-Related Diseases

Sirtuins are the class III of histone deacetylases whose deacetylate of histones is dependent on nicotinamide adenine dinucleotide (NAD+). Among seven sirtuins, SIRT1 plays a critical role in modulating a wide range of physiological processes, including apoptosis, DNA repair, inflammatory response, metabolism, cancer, and stress. Neuroinflammation is associated with many neurological diseases, including ischemic stroke, bacterial infections, traumatic brain injury, Alzheimer's disease (AD), and Parkinson's disease (PD). Recently, numerous studies indicate the protective effects of SIRT1 in neuroinflammation-related diseases. Here, we review the latest progress regarding the anti-inflammatory and neuroprotective effects of SIRT1. First, we introduce the structure, catalytic mechanism, and functions of SIRT1. Next, we discuss the molecular mechanisms of SIRT1 in the regulation of neuroinflammation. Finally, we analyze the mechanisms and effects of SIRT1 in several common neuroinflammation-associated diseases, such as cerebral ischemia, traumatic brain injury, spinal cord injury, AD, and PD. Taken together, this information implies that SIRT1 may serve as a promising therapeutic target for the treatment of neuroinflammation-associated disorders.

LncRNA TUG1 reduces inflammation and enhances insulin sensitivity in white adipose tissue by regulating miR-204/SIRT1 axis in obesity mice

Prevalence of obesity becomes an important health issue worldwide, but the management of obesity remains unsatisfied. This study aimed to explore the mechanism of long non-coding RNA TUG/miR-204/SIRT1 axis, which was involved in the pathogenesis of obesity. Obesity mouse model was induced by high-fat diet and treated with taurine upregulated gene1 (TUG1) virus via tail intravenous injection. Then, body weight, serum glucose, insulin tolerance, testicular fat weight were detected, as well as the expression of TUG1, microRNA-204 (miR-204), sirtuin1 (SIRT1), and inflammation and fatty accumulation associated proteins and cytokines. Regulatory relationship between TUG1/SIRT1 and miR-204 was confirmed by dual-luciferase reporter activity assay. A high-glucose-induced 3T3-L1 cell model was also constructed to explore the regulatory mechanism of TUG/miR-204/SIRT1 axis in the pathogenesis of obesity at cell level after altering the expression of TUG1, miR-204, and SIRT1. Overexpression of TUG1 could significantly attenuate the weight, serum glucose, glucose, insulin tolerance, fatty accumulation, and inflammation in obesity mice, as well as the elevation of miR-204, but increase the expression of SIRT1, phosphorylated AKT (p-AKT), glucose transporter4 (GLUT4), and peroxisome proliferator activated receptorγ (PPARγ). Both TUG1 and SIRT1 were targets of miR-204 and could be negatively regulated by miR-204. Overexpression of TUG1 could suppress the inflammation in adipocytes via downregulating miR-204 and promote GLUT4/PPARγ/AKT pathway high-glucose-induced inflammation in 3T3-L1 cells. miR-204 inhibitors could also suppress high-glucose-induced inflammation in 3T3-L1 cells via promoting SIRT1/ GLUT4/PPARγ/AKT pathway. LncRNA TUG1 could negatively regulate miR-204 to alleviate inflammation and insulin tolerance via promoting SIRT1/GLUT4/PPARγ/AKT pathway.

The Regulation of microRNAs in Alzheimer's Disease

MicroRNAs are small non-coding nucleic acids that are responsible for regulating the gene expression by binding to the coding region and 3' and 5' un-translated region of target messenger RNA. Approximately 70% of known microRNAs are expressed in the brain and increasing evidences demonstrate the possible involvement of microRNAs in Alzheimer's disease (AD) according to the statistics. The characteristic symptoms of AD are the progressive loss of memory and cognitive functions due to the deposition of amyloid β (Aβ) peptide, intracellular aggregation of hyperphosphorylated Tau protein, the loss of synapses, and neuroinflammation, as well as dysfunctional autophagy. Therefore, microRNA-mediated regulation for above-mentioned changes may be the potential therapeutic strategies for AD. In this review, the role of specific microRNAs involved in AD and corresponding applications are systematically discussed, including positive effects associated with the reduction of Aβ or Tau protein, the protection of synapses, the inhibition of neuroinflammation, the mitigation of aging, and the induction of autophagy in AD. It will be beneficial to develop effective targets for establishing a cross link between pharmacological intervention and AD in the near future.

Antioxidant Alternatives in the Treatment of Amyotrophic Lateral Sclerosis: A Comprehensive Review

Amyotrophic lateral sclerosis (ALS) is a neurodegenerative disease that produces a selective loss of the motor neurons of the spinal cord, brain stem and motor cortex. Oxidative stress (OS) associated with mitochondrial dysfunction and the deterioration of the electron transport chain has been shown to be a factor that contributes to neurodegeneration and plays a potential role in the pathogenesis of ALS. The regions of the central nervous system affected have high levels of reactive oxygen species (ROS) and reduced antioxidant defenses. Scientific studies propose treatment with antioxidants to combat the characteristic OS and the regeneration of nicotinamide adenine dinucleotide (NAD+) levels by the use of precursors. This review examines the possible roles of nicotinamide riboside and pterostilbene as therapeutic strategies in ALS.

Triptolide Suppressed the Microglia Activation to Improve Spinal Cord Injury Through miR-96/IKKβ/NF-κB Pathway

STUDY DESIGN

The effect of triptolide on spinal cord injury (SCI) and inflammatory response was observed by establishing SCI rat model. And in vitro experiments were conducted to determine the underlying mechanism of triptolide-mediated in murine microglial cell line BV2.

OBJECTIVE

To determine the underlying mechanism of triptolide in suppressing the microglia activation to improve SCI.

SUMMARY OF BACKGROUND DATA

Triptolide, as a major active ingredient of Chinese herb Tripterygium wilfordii, can promote spinal cord repair through inhibiting microglia activation, but the underlying mechanism is not clear.

METHODS

Locomotion recovery was accessed by Basso, Beattie, and Bresnahan score, the number of footfalls, stride length, and angle of rotation analysis. Expressions of microRNA 96 (miR-96), microglia activation marker Iba-1, and IκB kinase (IKKβ)/nuclear factor (NF)-κB-related proteins were detected by qRT-PCR or western blot. Inflammatory cytokines tumor necrosis factor-α and interleukin -1β were measured by enzyme-linked immuno sorbent assay. The regulation of miR-96 on IKKβ was confirmed by dual luciferase reporter assay.

RESULTS

Triptolide promoted locomotion recovery of SCI rats, upregulated the expression of miR-96, decreased microglia activation marker Iba-1 and IKKβ/NF-κB-related proteins, and inhibited inflammatory cytokines tumor necrosis factor-α and interleukin-1β levels in spinal cord tissues and lipopolysaccharide -induced microglia. Triptolide suppressed the microglia activation and inflammatory cytokines secretion in BV2 cells through up-regulating miR-96. We confirmed the interaction between miR-96 and IKKβ, and IKKβ expression was negatively regulated by miR-96. Finally, we determined that triptolide suppressed the microglia activation and inflammatory cytokines secretion through miR-96/IKKβ pathway.

CONCLUSION

Triptolide suppressed microglia activation after SCI through miR-96/IKKβ/NF-κB pathway.

LEVEL OF EVIDENCE

N/A.

Sirtuins in Multiple Sclerosis: The crossroad of neurodegeneration, autoimmunity and metabolism

Multiple Sclerosis (MS) is a challenging and disabling condition particularly in the secondary progressive (SP) phase of this disease. The available treatments cannot ameliorate or stop disease progression in this phase, and there is an urgent need to focus on effective therapies and the molecular pathways involved SPMS. Given the significant impact of neurodegeneration, autoimmunity and metabolic alterations in MS, focusing on the molecules that target these different pathways could help in finding new treatments. Sirtuins (SIRTs) are NAD⁺ dependent epigenetic and metabolic regulators, which have critical roles in the physiology of central nervous system, immune system and metabolism. Based on these facts, SIRTs are crucial candidates of therapeutic targets in MS and collecting the information related to MS disease for each SIRT individually is noteworthy and highlights the lack of investigation in each part. In this review we summarized the role of different sirtuins as key regulator in neurodegeneration, autoimmunity and metabolism pathways. We also clarify the rationale behind selecting SIRTs as therapeutic targets in MS disease by collecting the researches showing alteration of these proteins in human samples of MS patients and animal model of MS, and also the improvement of modeled animals after SIRT-directed treatments.

Screening Analysis of Sirtuins Family Expression on Anti-Inflammation of Resveratrol in Endothelial Cells

Background

Resveratrol has been shown to possess beneficial activities including antioxidant, anti-inflammatory, and cardioprotective effects through activating a nicotinamide adenine dinucleotide (NAD)-dependent histone deacetylase family member sirtuin-1 (SIRT1) protein. The current study was undertaken to investigate the role of sirtuin family members (SIRT1–SIRT7) on the anti-inflammation activities of resveratrol in endothelial cells.

Material/Methods

Primary human umbilical vein endothelial cells (HUVECs) were pretreated with resveratrol before tumor necrosis factor (TNF)-α (10–20 μg/L) stimulation. Cell viability was measured using the Cell Counting Kit-8 method. Total RNA was extracted after different treatments and the NimbleGen Human 12×135K Gene Expression Array was applied to screen and analyze SIRTs expression. Quantitative real-time polymerase chain reaction and western blot were applied to verify the results of the gene expression microarrays. Reactive oxygen species (ROS) production was examined using flow cytometry analysis.

Results

Microarray analysis showed that the expressions of SIRT1, SIRT2, SIRT3, SIRT5, SIRT6, and SIRT7 showed the tendency to increase while SIRT4 showed the tendency to decrease. SIRT1, SIRT2, SIRT5, and SIRT7 gene expression could be upregulated by pretreatment with resveratrol compared with TNF-α alone while there were no obvious differences of SIRT3, SIRT4, and SIRT6 expressions observed in TNF-α alone treated cells and resveratrol-TNF-α co-treated cells. Interestingly, SIRT1, SIRT2, SIRT3, SIRT4, and SIRT5 siRNA could reverse the effect of resveratrol on ROS production; SIRT1 and SIRT5 siRNA could significantly increase CD40 expression inhibited by resveratrol in TNF-α treated cells.

Conclusions

Our results suggest that resveratrol inhibiting oxidative stress production is associated with SIRT1, SIRT2, SIRT3, SIRT4, and SIRT5 pathways; attenuating CD40 expression was only associated with SIRT1 and SIRT5 pathways in TNF-α-induced endothelial cells injury.

MicroRNAs in Microglia: How do MicroRNAs Affect Activation, Inflammation, Polarization of Microglia and Mediate the Interaction Between Microglia and Glioma?

The essential roles of microglia in maintaining homeostasis in the healthy brain and contributing to neuropathology are well documented. Emerging evidence suggests that epigenetic modulation regulates microglial behavior in both physiological and pathological conditions. MicroRNAs (miRNAs) are short, non-coding epigenetic regulators that repress target gene expression mostly via binding to 3'-untranslated region (3'-UTR) of mRNA in a Dicer-dependent manner. Dysregulation of certain miRNAs can contribute to microglial hyper-activation, persistent neuroinflammation, and abnormal macrophage polarization in the brain. These abnormal conditions can support the pathogenesis of neurological disorders such as glioma, Alzheimer's disease (AD), amyotrophic lateral sclerosis (ALS), stroke, ischemia, and spinal cord injury (SCI). However, the roles of miRNAs in microglia in health and neurological disease have not been systematically summarized. This review will first report the role of Dicer, a key endoribonulease that is responsible for most miRNA biogenesis in microglia. Second, we will focus on recent research about the function of miRNAs in activation, inflammation and polarization of microglia, respectively. In addition, potential crosstalk between microglia and glioma cells via miRNAs will be discussed in this part. Finally, the role of two essential miRNAs, miR-124, and miR-155, in microglia will be highlighted.

Natural products as a potential modulator of microglial polarization in neurodegenerative diseases

Neurodegenerative diseases (NDs) are characterized by the progressive loss of structure and function of neurons most common in elderly population, mainly including Alzheimer's disease (AD), Parkinson's disease (PD), amyotrophic lateral sclerosis (ALS) and multiple sclerosis (MS). Neuroinflammation caused by microglia as the resident macrophages of the central nervous system (CNS) plays a contributory role in the onset and progression of NDs. Activated microglia, as in macrophages, to be heterogeneous, can polarize into M1 (pro-inflammatory) and M2 (anti-inflammatory) functional phenotypes. The former elaborate pro-inflammatory mediators promoting neuroinflammation and neuronal damage. In contrast, the latter generate anti-inflammatory mediators and neurotrophins that inhibit neuroinflammation and promote neuronal healing. Consistently, the regulation of microglial polarization from M1 to M2 phenotype appears as an outstanding therapeutic and preventive approach for NDs treatment. Although non-steroidal anti-inflammatory drugs (NSAIDs) currently used to alleviate M1 microglia-associated neuroinflammation responsible for the development of NDs, these drugs have different degrees of adverse effects and limited efficacy. As the advantages of novel structure, multi-target, high efficiency and low toxicity, natural products as the modulators of microglial polarization have attracted considerable concerns in the therapeutic areas of NDs. In this review, we mainly summarized the therapeutic potential of natural products and their various molecular mechanisms for NDs treatment through modulating microglial polarization. The aim of the current review is expected to be useful to develop innovative modulators of microglial polarization from natural products for the amelioration and treatment of NDs.

MicroRNA-204-5p suppresses IL6-mediated inflammatory response and chemokine generation in HK-2 renal tubular epithelial cells by targeting IL6R

During the pathogenetic process of varied kidney diseases, renal tubules are the major sites in response to detrimental insults, including pro-inflammatory stimuli. MicroRNA-204-5p (miR-204-5p) can be detected in the renal tubular epithelial cells in the normal kidney; its expression, however, is downregulated in the kidney with pathological changes. This study aimed to investigate the role of miR-204-5p in interleukin 6 (IL6) mediated inflammatory response and chemokine production in HK-2 renal tubular cells. In HK-2 cells, the expression of miR-204-5p was downregulated in response to exogenous pro-inflammatory stimulus, tumor necrosis factor α (TNFα), or IL1β, while that of IL6 receptor α (IL6R) was upregulated. Dual-luciferase results confirmed that miRNA-204-5p directly targeted IL6R. In addition to suppressing IL6R expression, miRNA-204-5p agomir also inhibited the phosphorylation of signal transducer and activator of transcription 3 (STAT3) in HK-2 cells exposed to exogenous IL6. Further, miRNA-204-5p suppressed the overproduction of pro-inflammatory mediators (cyclooxygenase 2 and prostaglandin E2) and chemokines (C–C motif chemokine ligand 2 and C–X–C motif chemokine ligand 8). The anti-inflammatory effects of miRNA-204-5p were attenuated when IL6R was reexpressed in HK-2 cells. Collectively, our study reveals that miR-204-5p inhibits the inflammation and chemokine generation in renal tubular epithelial cells by modulating the IL6/IL6R axis.

Induction of Autophagy and Activation of SIRT-1 Deacetylation Mechanisms Mediate Neuroprotection by the Pomegranate Metabolite Urolithin A in BV2 Microglia and Differentiated 3D Human Neural Progenitor Cells

SCOPE

Urolithin A is an anti-inflammatory and neuroprotective gut-derived metabolite from ellagitannins and ellagic acid in pomegranate, berries, and nuts. The roles of SIRT-1 and autophagy in the neuroprotective activity of urolithin A are investigated.

METHODS AND RESULTS

Analyses of culture supernatants from lipopolysaccharide-stimulated BV2 microglia show that urolithin A (2.5-10 µm) produced significant reduction in the production of nitrite, tumor necrosis factor (TNF)-α and IL-6. The anti-inflammatory effect of the compound is reversed in the presence of sirtuin (SIRT)-1 and the autophagy inhibitors EX527 and chloroquine, respectively. Protein analyses reveal reduction in p65 and acetyl-p65 protein. Treatment of BV2 microglia with urolithin A results in increased SIRT-1 activity and nuclear protein, while induction of autophagy by the compound is demonstrated using autophagy fluorescent and autophagy LC3 HiBiT reporter assays. Viability assays reveal that urolithin A produces a neuroprotective effect in APPSwe-transfected ReNcell VM human neural cells, which is reversed in the presence of EX527 and chloroquine. Increase in both SIRT-1 and autophagic activities are also detected in these cells following treatment with urolithin A.

CONCLUSIONS

It has been proposed that SIRT-1 activation and induction of autophagy are involved in the neuroprotective activity of urolithin A in brain cells.

Adenosine receptors as a new target for resveratrol-mediated glioprotection

Resveratrol, a natural polyphenolic compound, has been studied as a neuroprotective molecule. Our group has demonstrated that such effect is closely associated with modulation of glial functionality, but the underlying mechanisms are not fully understood. Because astrocytes actively participate in the brain inflammatory response, and activation of adenosine receptors can attenuate inflammatory processes, the aim of this study was to investigate the role of adenosine receptors as a mechanism for resveratrol glioprotection, particularly regarding to neuroinflammation. Therefore, primary astrocyte cultures were co-incubated with resveratrol and selective antagonists of A₁, A_2A, and A₃ adenosine receptors, as well as with caffeine (a non-selective adenosine receptor antagonist), and then challenged with bacterial inflammogen lipopolysaccharide (LPS). Caffeine and selective adenosine receptor antagonists abolished the anti-inflammatory effect of resveratrol. In accordance with these effects, resveratrol prevented LPS-induced decrease in mRNA levels of adenosine receptors. Resveratrol could also prevent the activation of pro-inflammatory signaling pathways, such as nuclear factor κB (NFκB) and p38 mitogen-activated protein kinase (p38 MAPK) in a mechanism dependent on adenosine receptors. Conversely, trophic factors and protective signaling pathways, including sirtuin 1 (SIRT1), nuclear factor erythroid 2-related factor 2 (Nrf2), heme oxygenase-1 (HO-1), and phosphoinositide 3-kinase (PI3K)/Akt were positively modulated by resveratrol in both LPS-stimulated and unstimulated astrocytes, but adenosine receptor antagonism did not abrogate all effects of resveratrol. To our knowledge, our data provide the first evidence that adenosine receptors are involved in the anti-inflammatory activity of resveratrol in astrocytes, thus exerting an important role for resveratrol-mediated glioprotection.

Visfatin is regulated by interleukin‑6 and affected by the PPAR‑γ pathway in BeWo cells

Visfatin, an adipocytokine and cytosolic enzyme with nicotinamide phosphoribosyltransferase (Nampt) activity, is involved in the pathogenesis of numerous metabolic disorders. In addition, the nuclear receptor peroxisome proliferator-activated receptor-γ (PPAR-γ) serves important roles in anti-inflammatory reactions and regulates glucose and lipid metabolism. The aim of the present study was to investigate the effect of interleukin-6 (IL-6) on the expression and secretion of visfatin in BeWo cells, and to determine whether the PPAR-γ pathway is involved in the regulation of visfatin by IL-6. Therefore, BeWo cells were stimulated with serial concentrations of IL-6 or pioglitazone, and the expression levels of visfatin and PPAR-γ were determined by reverse transcription-quantitative polymerase chain reaction and western blotting. The results of the present study demonstrated that IL-6 downregulated the mRNA levels of visfatin and PPAR-γ, which were strongly associated. Activation of PPAR-γ by pioglitazone resulted in significantly increased expression of visfatin, which abrogated the inhibitory effect of IL-6 on visfatin in BeWo cells. Furthermore, treatment using pioglitazone alone increased the expression and secretion of the visfatin protein, compared with the control or IL-6 alone group. In summary, the findings of the present study suggested that IL-6 inhibited the expression of visfatin and PPAR-γ at the transcriptional level; in addition, activation of PPAR-γ upregulated visfatin at the mRNA and protein expression levels. Therefore, the PPAR-γ signaling pathway may be involved in the regulation of visfatin by IL-6 in BeWo cells. These results may provide novel insight into the roles of visfatin in trophoblastic cells. Furthermore, thiazolidinedione pioglitazone, by upregulating visfatin expression, may promote the energy metabolism of trophoblastic cells, maintain the function of the placenta and improve the outcome of pregnancy.

Probing the mechanism of SIRT1 activation by a 1,4-dihydropyridine

The NAD⁺-dependent deacetylase SIRT1 plays important roles in several physiological processes such as transcription, genome stability, stress responses, and aging. Due to its diverse role in metabolisms, SIRT1 has emerged as a potential therapeutic target in many human disorders such as type II diabetes, cardiovascular and neurodegenerative diseases, and cancer. Recent studies have reported that modulation of SIRT1 activity by phenolic activators like resveratrol and some 1,4-dihydropyridines (1,4-DHPs) can inhibit tumor growth by promoting apoptosis in cancer cells. However, the mechanism of SIRT1 activation is still not clear. In this report, we have tried to elucidate the mechanism of SIRT1 activation from studies on its interaction with a synthetic 1,4-DHP derivative (DHP-8; 3,5-diethoxy carbonyl-4-(4-nitrophenyl)-2,6-dimethyl-1,4-dihydropyridine) using molecular modeling, docking, simulation, and free energy analyses. Owing to the absence of full-length human SIRT1 structure, multi-template based modeling approach was opted followed by docking of DHP-8 at its allosteric site. In presence of DHP-8, the overall conformation of SIRT1 was found to be more stable (especially at its substrate binding sites) with a large structural variation at its N-terminal domain while bound to substrate p53 or p53-W. Determination of the MM/PBSA free energy indicated that the binding of DHP-8 to SIRT1 significantly increased the binding affinity of SIRT1 to its substrate p53-W as well as to NAD⁺. Overall, this study depicts the atomistic detailed mechanism for the direct activation of SIRT1 by a 1,4-DHP. This would serve to develop new SIRT1 activators for future therapeutic perspectives.

RNA-Seq transcriptomic profiling of primary murine microglia treated with LPS or LPS + IFNγ

Microglia, the main resident immune cells in the CNS, are thought to participate in the pathogenesis of various neurological disorders. LPS and LPS + IFNγ are stimuli that are widely used to activate microglia. However, the transcriptomic profiles of microglia treated with LPS and LPS + IFNγ have not been properly compared. Here, we treated murine primary microglial cultures with LPS or LPS + IFNγ for 6 hours and then performed RNA-Sequencing. Gene expression patterns induced by the treatments were obtained by WGCNA and 11 different expression profiles were found, showing differential responses to LPS and LPS + IFNγ in many genes. Interestingly, a subset of genes involved in Parkinson’s, Alzheimer’s and Huntington’s disease were downregulated by both treatments. By DESeq analysis we found differentially upregulated and downregulated genes that confirmed LPS and LPS + IFNγ as inducers of microglial pro-inflammatory responses, but also highlighted their involvement in specific cell functions. In response to LPS, microglia tended to be more proliferative, pro-inflammatory and phagocytic; whereas LPS + IFNγ inhibited genes were involved in pain, cell division and, unexpectedly, production of some inflammatory mediators. In summary, this study provides a detailed description of the transcriptome of LPS- and LPS + IFNγ treated primary microglial cultures. It may be useful to determine whether these in vitro phenotypes resemble microglia in in vivo pathological conditions.

How to reprogram microglia toward beneficial functions

Microglia, brain cells of nonneural origin, orchestrate the inflammatory response to diverse insults, including hypoxia/ischemia or maternal/fetal infection in the perinatal brain. Experimental studies have demonstrated the capacity of microglia to recognize pathogens or damaged cells activating a cytotoxic response that can exacerbate brain damage. However, microglia display an enormous plasticity in their responses to injury and may also promote resolution stages of inflammation and tissue regeneration. Despite the critical role of microglia in brain pathologies, the cellular mechanisms that govern the diverse phenotypes of microglia are just beginning to be defined. Here we review emerging strategies to drive microglia toward beneficial functions, selectively reporting the studies which provide insights into molecular mechanisms underlying the phenotypic switch. A variety of approaches have been proposed which rely on microglia treatment with pharmacological agents, cytokines, lipid messengers, or microRNAs, as well on nutritional approaches or therapies with immunomodulatory cells. Analysis of the molecular mechanisms relevant for microglia reprogramming toward pro‐regenerative functions points to a central role of energy metabolism in shaping microglial functions. Manipulation of metabolic pathways may thus provide new therapeutic opportunities to prevent the deleterious effects of inflammatory microglia and to control excessive inflammation in brain disorders.