Dipeptidyl Vinyl Sulfone as a Novel Chemical Tool to Inhibit HMGB1/NLRP3-Inflammasome and Inflamma-miRs in Aβ-Mediated Microglial Inflammation

Pathophysiological role of high mobility group box-1 signaling in neurodegenerative diseases

Nucleocytoplasmic translocation of HMGB1 (high mobility group box-1) plays a significant role in disease progression. Several methods contribute to the translocation of HMGB1 from the nucleus to the cytoplasm, including inflammasome activation, TNF-α signaling, CRM1-mediated transport, reactive oxygen species (ROS), JAK/STAT pathway, RIP3-mediated p53 involvement, XPO-1-mediated transport, and calcium-dependent mechanisms. Due to its diverse functions at various subcellular locations, HMGB1 has been identified as a crucial factor in several Central Nervous System (CNS) disorders, including Huntington's disease (HD), Parkinson's disease (PD), and Alzheimer's disease (AD). HMGB1 displays a wide array of roles in the extracellular environment as it interacts with several receptors, including CXCR4, TLR2, TLR4, TLR8, and RAGE, by engaging in these connections, HMGB1 can effectively regulate subsequent signaling pathways, hence exerting an impact on the progression of brain disorders through neuroinflammation. Therefore, focusing on treating neuroinflammation could offer a common therapeutic strategy for several disorders. The objective of the current literature is to demonstrate the pathological role of HMGB1 in various neurological disorders. This review also offers insights into numerous therapeutic targets that promise to advance multiple treatments intended to alleviate brain illnesses.

Mechanistic and therapeutic role of NLRP3 inflammasome in the pathogenesis of Alzheimer's disease

Alzheimer's disease (AD), a progressive neurodegenerative disorder, has emerged as the most common form of dementia in the elderly. Several pathological hallmarks have been identified, including neuroinflammation. A comprehensive insight into the underlying mechanisms that can fuel the development of novel therapeutic approaches is necessary because of the alarmingly rapid increase in the frequency of incidence. Recently, NLRP3 inflammasome was identified as a critical mediator of neuroinflammation. Activation of nucleotide-binding domain (NOD)-like receptor protein 3 (NLRP3) inflammasome by amyloid, neurofibrillary tangles, impaired autophagy and endoplasmic reticulum stress, triggers the release of pro-inflammatory cytokines such as IL-1β and IL-18. Subsequently, these cytokines can promote neurodegeneration and cognitive impairment. It is well established that genetic or pharmacological ablation of NLRP3 alleviates AD-related pathological features in in vitro and in vivo models. Therefore, several synthetic and natural compounds have been identified that exhibit the potential to inhibit NLRP3 inflammasome and alleviate AD-associated pathology. The current review article will highlight the various mechanisms by which activation of NLRP3 inflammation occurs during Alzheimer's disease, and how it influences neuroinflammation, neurodegeneration and cognitive impairment. Moreover, we will summarise the different small molecules that possess the potential to inhibit NLRP3 and can pave the path for developing novel therapeutic interventions for AD.

An ALS-associated mutation dysregulates microglia-derived extracellular microRNAs in a sex-specific manner

Evidence suggests the presence of microglial activation and microRNA (miRNA) dysregulation in amyotrophic lateral sclerosis (ALS), the most common form of adult motor neuron disease. However, few studies have investigated whether the miRNA dysregulation originates from microglia. Furthermore, TDP-43 (encoded by TARDBP), involved in miRNA biogenesis, aggregates in tissues of ∼98% of ALS cases. Thus, this study aimed to determine whether expression of the ALS-linked TDP-43M337V mutation in a transgenic mouse model dysregulates microglia-derived miRNAs. RNA sequencing identified several dysregulated miRNAs released by transgenic microglia and a differential miRNA release by lipopolysaccharide-stimulated microglia, which was more pronounced in cells from female mice. We validated the downregulation of three candidate miRNAs, namely, miR-16-5p, miR-99a-5p and miR-191-5p, by reverse transcription quantitative polymerase chain reaction (RT-qPCR) and identified their predicted targets, which primarily include genes involved in neuronal development and function. These results suggest that altered TDP-43 function leads to changes in the miRNA population released by microglia, which may in turn be a source of the miRNA dysregulation observed in the disease. This has important implications for the role of neuroinflammation in ALS pathology and could provide potential therapeutic targets.

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.

Effects of Diabetes Mellitus-Related Dysglycemia on the Functions of Blood-Brain Barrier and the Risk of Dementia

Diabetes mellitus is one of the most common metabolic diseases worldwide, and its long-term complications include neuropathy, referring both to the peripheral and to the central nervous system. Detrimental effects of dysglycemia, especially hyperglycemia, on the structure and function of the blood-brain barrier (BBB), seem to be a significant backgrounds of diabetic neuropathy pertaining to the central nervous system (CNS). Effects of hyperglycemia, including excessive glucose influx to insulin-independent cells, may induce oxidative stress and secondary innate immunity dependent inflammatory response, which can damage cells within the CNS, thus promoting neurodegeneration and dementia. Advanced glycation end products (AGE) may exert similar, pro-inflammatory effects through activating receptors for advanced glycation end products (RAGE), as well as some pattern-recognition receptors (PRR). Moreover, long-term hyperglycemia can promote brain insulin resistance, which may in turn promote Aβ aggregate accumulation and tau hyperphosphorylation. This review is focused on a detailed analysis of the effects mentioned above towards the CNS, with special regard to mechanisms taking part in the pathogenesis of central long-term complications of diabetes mellitus initiated by the loss of BBB integrity.

Multifunctional Selenium Nanoparticles with Different Surface Modifications Ameliorate Neuroinflammation through the Gut Microbiota-NLRP3 Inflammasome-Brain Axis in APP/PS1 Mice

Neuroinflammation plays a critical role in Alzheimer's disease (AD). However, it is still unknown if neuroinflammation can be effectively treated using selenium nanoparticles (SeNPs) with different surface modifications. In this study, SeNPs were coated with dihydromyricetin (DMY), a natural polyphenol, to obtain DMY@SeNPs. Given that DMY@SeNPs are unstable under physiological conditions, they were decorated step-by-step with chitosan (CS/DMY@SeNPs) and with the blood brain barrier (BBB) targeting peptide Tg (TGNYKALHPHNG) to yield Tg-CS/DMY@SeNPs, which significantly reduced the aggregation of Aβ and improved the anti-inflammatory effects of SeNPs in vitro. The mechanisms of CS/DMY@SeNPs and Tg-CS/DMY@SeNPs on regulating neuroinflammation are different. Only Tg-CS/DMY@SeNPs can cross the BBB; therefore, Tg-CS/DMY@SeNPs more successfully inhibited Aβ aggregation and reduced inflammatory cytokine secretion via the NF-κB pathway in the brain of APP/PS1 mice compared to CS/DMY@SeNPs. Furthermore, both types of nanoparticles, however, were able to repair the gut barrier and regulate the population of inflammatory-related gut microbiota such as Bifidobacterium, Dubosiella, and Desulfovibrio. Of note, the relative abundance of Gordonibacter was only enhanced by Tg-CS/DMY@SeNPs, thereby downregulating the protein expression of the NLRP3 inflammasome and the concentrations of serum inflammatory factors. This demonstrates that Tg-CS/DMY@SeNPs ameliorate neuroinflammation through the gut microbiota-NLRP3 inflammasome-brain axis. Overall, our data suggest that Tg-CS/DMY@SeNPs are an ideal drug candidate for AD treatment.

HMGB1 signaling pathway in diabetes-related dementia: Blood-brain barrier breakdown, brain insulin resistance, and Aβ accumulation

Diabetes contributes to the onset of various diseases, including cancer and cardiovascular and neurodegenerative diseases. Recent studies have highlighted the similarities and relationship between diabetes and dementia as an important issue for treating diabetes-related cognitive deficits. Diabetes-related dementia exhibits several features, including blood-brain barrier disruption, brain insulin resistance, and Aβ over-accumulation. High-mobility group box1 (HMGB1) is a protein known to regulate gene transcription and cellular mechanisms by binding to DNA or chromatin via receptor for advanced glycation end-products (RAGE) and toll-like receptor 4 (TLR4). Recent studies have demonstrated that the interplay between HMGB1, RAGE, and TLR4 can impact both neuropathology and diabetic alterations. Herein, we review the recent research regarding the roles of HMGB1-RAGE-TLR4 axis in diabetes-related dementia from several perspectives and emphasize the importance of the influence of HMGB1 in diabetes-related dementia.

Role of Lipocalin-2 in Amyloid-Beta Oligomer-Induced Mouse Model of Alzheimer's Disease

Lipocalin-2 (LCN2) is an inflammatory protein with diverse functions in the brain. Although many studies have investigated the mechanism of LCN2 in brain injuries, the effect of LCN2 on amyloid-toxicity-related memory deficits in a mouse model of Alzheimer’s disease (AD) has been less studied. We investigated the role of LCN2 in human AD patients using a mouse model of AD. We created an AD mouse model by injecting amyloid-beta oligomer (AβO) into the hippocampus. In this model, animals exhibited impaired learning and memory. We found LCN2 upregulation in the human brain frontal lobe, as well as a positive correlation between white matter ischemic changes and serum LCN2. We also found increased astrocytic LCN2, microglia activation, iron accumulation, and blood–brain barrier disruption in AβO-treated hippocampi. These findings suggest that LCN2 is involved in a variety of amyloid toxicity mechanisms, especially neuroinflammation and oxidative stress.

Overexpression of TRIM3 protects against LPS-induced acute kidney injury via repressing IRF3 pathway and NLRP3 inflammasome

PURPOSE

The pathological process of sepsis involves multiple system organs, including kidney. Sepsis-induced acute kidney injury (AKI) has high morbidity and high mortality. Overproduced inflammatory factors contribute to the occurrence and evolvement of AKI. Here, the role and underlying mechanism of tripartite motif containing 3 (TRIM3) and in AKI was explored.

METHODS

Lipopolysaccharide (LPS) was used for constructing AKI model both in vitro and in vivo. RT-PCR and western blot were performed to detect TRIM3, Interferon regulatory factor 3 (IRF3) and NLRP3-ASC-Caspase1 inflammasome. Upon selectively regulating the TRIM3 or IRF3 expression, the proliferation, apoptosis and inflammatory response were detected. The interaction between TRIM3 and IRF3 was verified by Immunoprecipitation (IP).

RESULTS

TRIM3 was down-regulated in mediated injury renal tubular epithelial cell line HK-2 treated with LPS. Overexpression of TRIM3 promoted cell viability and reduced apoptosis. In addition, overexpression of TRIM3 inhibited the expression of inflammatory factors (IL-1β, IL-6, TNF-α and IL-18), dampened the phosphorylation of IRF3 and repressed NLRP3 inflammasome activation. Furthermore, TRIM3 overexpression significantly eased the LPS-induced damage on AKI rat model and decreased the serum creatinine and urea nitrogen levels in rat kidney tissues. The results of immunohistochemistry (IHC) and Western blot manifested that TRIM3 was increased dramatically after TRIM3 was overexpressed in the rat kidney tissues, while IRF3 and NLRP3-ASC-Caspase1 inflammasome were significantly repressed following TRIM3 upregulation in the kidney tissues. Mechanistically, TRIM3 interacted with IRF3 and inhibited its phosphorylation.

CONCLUSION

Overexpression of TRIM3 protected against LPS-induced AKI by inhibiting the IRF3 pathway and NLRP3 inflammasome activation.

Capillin protects against non-alcoholic steatohepatitis through suppressing NLRP3 inflammasome activation and oxidative stress

BACKGROUND

Non-alcoholic steatohepatitis (NASH) is an extreme form of non-alcoholic fatty liver disease. The present study concentrated on the role of Capillin, a polyacetylene compound isolated from Artemisia capillaris Thunb., in NASH development.

MATERIALS AND METHODS

Palmitic acid (PA) was treated with FL83B hepatocytes, and high-fat diet was given to mouse to construct the NASH model in vivo. The 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) method, flow cytometry, and terminal deoxynucleotidyl transferase-mediated dUTP nick end labeling (TUNEL) assay were carried out to measure the viability and apoptosis of FL83B hepatocytes. Quantitative reverse transcription-polymerase chain reaction (qRT-PCR) was performed to measure the mRNA expressions of infiltration markers (Cd11c, Ccr2, and Ly6c), fibrosis genes (Tgfβ1, Col1a1, and Timp1), and alpha-smooth muscle actin (α-SMA). Western blot, immunofluorescence, and Enzyme-linked immunosorbent assay (ELISA) were implemented to examine the proteins of Caspase-3, Bcl2, Nrf2, HO-1, NLRP3, ASC, and Caspase-1, the ROS level, and oxidative stress markers (MDA, GSH-ST, SOD, and GSH-Px), and the lipid peroxidation level, respectively. Moreover, HE staining was manipulated to observe the histopathological changes in liver tissue.

RESULTS

Capillin hampered PA-mediated hepatocytes apoptosis and enhanced cell viability. Furthermore, Capillin suppressed PA-mediated oxidative stress in hepatocytes, promoted Nrf2/HO-1 expression, and repressed NLRP3-ASC-Caspase1 inflammasome. The in vivo studies indicated that Capillin vigorously improves liver fat accumulation, oxidative stress, and liver injury in NASH mice. Mechanistically, Capillin repressed NLRP3-ASC-Caspase1 inflammasome and up-regulated the Nrf2-HO-1 pathway in the liver.

CONCLUSION

Capillin ameliorates hepatocyte injury by dampening oxidative stress and repressing NLRP3 inflammasome in NASH mice.

MiR-216a-5p ameliorates learning-memory deficits and neuroinflammatory response of Alzheimer's disease mice via regulation of HMGB1/NF-κB signaling

OBJECTIVE

The objective of this study was to explore whether miR-216a-5p could affect the learning-memory ability and inflammatory response of Alzheimer's disease (AD) mice via regulation of the HMGB1/NF-κB pathway.

METHODS

Mice were divided into the normal (wild-type C57BL/6 mice), AD (APP/PS1 double-transgenic mice), AD + miR-216a-5p, and AD + vector groups. The Morris water maze test was used to examine learning and memory ability. Nissl staining and TUNEL staining were performed to observe the survival and apoptosis of hippocampal neurons. In addition, Aβ deposition and the expression of inflammatory cytokines were determined, while miR-216a-5p expression and HMGB1/NF-κB pathway-related proteins were detected by qRT-PCR and Western blotting, respectively.

RESULTS

AD mice exhibited decreased miR-216a-5p expression but increased HMGB-1 protein expression in the hippocampus, and these mice had a prolonged escape latency, fewer number of times crossing the platform location and shortened time in the target quadrant compared to those in normal mice. AD mice also had an elevated number of TUNEL-positive cells, increased deposition of Aβ, increased expression of inflammatory cytokines and decreased number of Nissl-positive cells. In addition, AD mice presented with downregulated expression of cytoplasmic NF-κB p65 protein but upregulated expression of nuclear NF-κB p65 protein. However, AD mice treated with miR-216a-5p exhibited significant improvements of the abovementioned parameters. The dual-luciferase reporter assay confirmed that HMGB1 is a target gene of miR-216a-5p.

CONCLUSION

MiR-216a-5p can improve learning-memory ability and attenuate the inflammatory response of AD mice through targeted inhibition of the HMGB1/NF-κB pathway.

Meta-Analysis of Methamphetamine Modulation on Amyloid Precursor Protein through HMGB1 in Alzheimer's Disease

The deposition of amyloid-beta (Aβ) through the cleavage of amyloid-beta precursor protein (APP) is a biomarker of Alzheimer’s disease (AD). This study used QIAGEN Ingenuity Pathway Analysis (IPA) to conduct meta-analysis on the molecular mechanisms by which methamphetamine (METH) impacts AD through modulating the expression of APP. All the molecules affected by METH and APP were collected from the QIAGEN Knowledge Base (QKB); 78 overlapping molecules were identified. Upon simulation of METH exposure using the “Molecule Activity Predictor” feature, eight molecules were found to be affected by METH and exhibited activation relationships on APP expression at a confidence of p = 0.000453 (Z-score = 3.51, two-tailed). Core Analysis of these eight molecules identified High Mobility Group Box protein 1 (HMGB1) signaling pathway among the top 5 canonical pathways with most overlap with the 8-molecule dataset. Simulated METH exposure increased APP expression through HMGB1 at a confidence of p < 0.00001 (Z-score = 7.64, two-tailed). HMGB1 is a pathogenic hallmark in AD progression. It not only increases the production of inflammatory mediators, but also mediates the disruption of the blood-brain barrier. Our analyses suggest the involvement of HMGB1 signaling pathway in METH-induced modulation of APP as a potential casual factor of AD.

Recovery of Depleted miR-146a in ALS Cortical Astrocytes Reverts Cell Aberrancies and Prevents Paracrine Pathogenicity on Microglia and Motor Neurons

Reactive astrocytes in Amyotrophic Lateral Sclerosis (ALS) change their molecular expression pattern and release toxic factors that contribute to neurodegeneration and microglial activation. We and others identified a dysregulated inflammatory miRNA profile in ALS patients and in mice models suggesting that they represent potential targets for therapeutic intervention. Such cellular miRNAs are known to be released into the secretome and to be carried by small extracellular vesicles (sEVs), which may be harmful to recipient cells. Thus, ALS astrocyte secretome may disrupt cell homeostasis and impact on ALS pathogenesis. Previously, we identified a specific aberrant signature in the cortical brain of symptomatic SOD1-G93A (mSOD1) mice, as well as in astrocytes isolated from the same region of 7-day-old mSOD1 mice, with upregulated S100B/HMGB1/Cx43/vimentin and downregulated GFAP. The presence of downregulated miR-146a on both cases suggests that it can be a promising target for modulation in ALS. Here, we upregulated miR-146a with pre-miR-146a, and tested glycoursodeoxycholic acid (GUDCA) and dipeptidyl vinyl sulfone (VS) for their immunoregulatory properties. VS was more effective in restoring astrocytic miR-146a, GFAP, S100B, HMGB1, Cx43, and vimentin levels than GUDCA, which only recovered Cx43 and vimentin mRNA. The miR-146a inhibitor generated typical ALS aberrancies in wild type astrocytes that were abolished by VS. Similarly, pre-miR-146a transfection into the mSOD1 astrocytes abrogated aberrant markers and intracellular Ca²⁺ overload. Such treatment counteracted miR-146a depletion in sEVs and led to secretome-mediated miR-146a enhancement in NSC-34-motor neurons (MNs) and N9-microglia. Secretome from mSOD1 astrocytes increased early/late apoptosis and FGFR3 mRNA in MNs and microglia, but not when derived from pre-miR-146a or VS-treated cells. These last strategies prevented the impairment of axonal transport and synaptic dynamics by the pathological secretome, while also averted microglia activation through either secretome, or their isolated sEVs. Proteomic analysis of the target cells indicated that pre-miR-146a regulates mitochondria and inflammation via paracrine signaling. We demonstrate that replenishment of miR-146a in mSOD1 cortical astrocytes with pre-miR-146a or by VS abrogates their phenotypic aberrancies and paracrine deleterious consequences to MNs and microglia. These results propose miR-146a as a new causal and emerging therapeutic target for astrocyte pathogenic processes in ALS.

Alzheimer's Disease Pathogenesis: Role of Autophagy and Mitophagy Focusing in Microglia

Alzheimer's disease (AD) is a debilitating neurological disorder, and currently, there is no cure for it. Several pathologic alterations have been described in the brain of AD patients, but the ultimate causative mechanisms of AD are still elusive. The classic hallmarks of AD, including amyloid plaques (Aβ) and tau tangles (tau), are the most studied features of AD. Unfortunately, all the efforts targeting these pathologies have failed to show the desired efficacy in AD patients so far. Neuroinflammation and impaired autophagy are two other main known pathologies in AD. It has been reported that these pathologies exist in AD brain long before the emergence of any clinical manifestation of AD. Microglia are the main inflammatory cells in the brain and are considered by many researchers as the next hope for finding a viable therapeutic target in AD. Interestingly, it appears that the autophagy and mitophagy are also changed in these cells in AD. Inside the cells, autophagy and inflammation interact in a bidirectional manner. In the current review, we briefly discussed an overview on autophagy and mitophagy in AD and then provided a comprehensive discussion on the role of these pathways in microglia and their involvement in AD pathogenesis.

Downregulation of lncRNA SNHG14 attenuates osteoarthritis by inhibiting FSTL-1 mediated NLRP3 and TLR4/NF-κB pathway through miR-124-3p

Osteoarthritis (OA) is the joint pain and dysfunction syndrome caused by severe joint degeneration. The overproduced inflammatory mediators contribute greatly to OA development. It is reported that long non-coding RNA (lncRNA) takes part in many inflammatory diseases. Here, we mainly explored the function of lncRNA SNHG14 in OA process and its specific mechanisms. An OA rat model was induced by destabilizing the medial meniscus (DMM) and IL-1β (5 ng/mL) was used to mediate an OA cell model in particular chondrocytes (AC). Gain- or loss-of functional assays of SNHG14 and miR-124-3p were carried out to explore their roles in OA development. The experimental statistics illustrated that lncRNA SNHG14 and IL-1β mRNA expression were both increased in OA tissues, while miR-124-3p was lowly-expressed. Linear regression analysis showed that SNHG14 and miR-124-3p had negative relationship in the OA tissues. In the in vitro experiments, downregulation of lncRNA SNHG14 promoted the proliferation of IL-1β-treated AC and inhibited cell apoptosis and COX-2, iNOS, TNF-α, IL-6 expression. Moreover, lncRNA SNHG14 inhibited miR-124-3p expression as a miRNA sponge. MiR-124-3p targeted the 3'non-translated region (3'UTR) of FSTL-1 and TLR4 and inhibited their expressions. Also, the in vivo experiments confirmed that knocking down SNHG14 relieved the progression of OA in rats via inhibiting inflammatory responses. In conclusion, this study confirmed that downregulation of lncRNA SNHG14 inhibits FSTL-1-mediated activation of NLRP3 and TLR4/NF-κB signalling pathway activation by targeting miR-124-3p, thus attenuating inflammatory reactions in OA.

LncRNA OIP5‑AS1 aggravates house dust mite‑induced inflammatory responses in human bronchial epithelial cells via the miR‑143‑3p/HMGB1 axis

Bronchial asthma poses a serious threat to human health. Previous studies have documented the role of long non‑coding RNAs (lncRNAs) in asthma. However, the molecular mechanism underlying bronchial asthma remains unclear. The aim of the present study was to evaluate the role of the lncRNA Opa‑interacting protein 5 antisense RNA1 (OIP5‑AS1) in the house dust mite‑induced inflammatory response in human bronchial epithelial cells. BEAS‑2B cells were treated with Dermatophagoides pteronyssinus peptidase 1 (Der p1) to establish an in vitro model of asthma. OIP5‑AS1 expression levels increased in BEAS‑2B cells following Der p1 treatment, while microRNA (miR)‑143‑3p was downregulated. Additionally, the levels of the pro‑inflammatory factors tumor necrosis factor‑α, interleukin (IL)‑6 and IL‑8 were measured, and apoptosis was evaluated following OIP5 silencing. OIP5‑AS1 knockdown reduced the inflammatory response and apoptosis in BEAS‑2B cells. Furthermore, using dual luciferase reporter assays and co‑transfection experiments, it was demonstrated that the function of OIP5‑AS1 was mediated by miR‑143‑3p. miR‑143‑3p overexpression attenuated the Der p1‑induced inflammatory response and apoptosis of BEAS‑2B cells by targeting high mobility group box 1 (HMGB1). In summary, OIP5‑AS1 exacerbated Der p1‑induced inflammation and apoptosis in BEAS‑2B cells by targeting miR‑143‑3p via HMGB1.

Lychee seed polyphenol protects the blood-brain barrier through inhibiting Aβ(25-35)-induced NLRP3 inflammasome activation via the AMPK/mTOR/ULK1-mediated autophagy in bEnd.3 cells and APP/PS1 mice

Blood-brain barrier (BBB) dysfunction has been implicated in Alzheimer's disease (AD) and is closely linked to the release of proinflammatory cytokines in brain capillary endothelial cells. We have previously reported that lychee seed polyphenols (LSP) exerted anti-neuroinflammatory effect. In this study, we aimed to explore the protective effect of LSP on BBB integrity. The monolayer permeability of bEnd.3 cells, and the mRNA level and protein expression of tight junction proteins (TJs), including Claudin 5, Occludin, and ZO-1, were examined. In addition, the inhibition of Aβ(25-35)-induced NLRP3 inflammasome activation, and the autophagy induced by LSP were investigated by detecting the expression of NLRP3, caspase-1, ASC, LC3, AMPK, mTOR, and ULK1. Furthermore, the cognitive function and the expression of TJs, NLRP3, caspase-1, IL-1β, and p62 were determined in APP/PS1 mice. The results showed that LSP significantly decreased the monolayer permeability and inhibited the NLRP3 inflammasome in Aβ(25-35)-induced bEnd3 cells. In addition, LSP induced autophagy via the AMPK/mTOR/ULK1 pathway in bEnd.3 cells, and improved the spatial learning and memory function, increased the TJs expression, and inhibited the expression of NLRP3, caspase-1, IL-1β, and p62 in APP/PS1 mice. Therefore, LSP protects BBB integrity in AD through inhibiting Aβ(25-35)-induced NLRP3 inflammasome activation via the AMPK/mTOR/ULK1-mediated autophagy.

Designer Cathinones N-Ethylhexedrone and Buphedrone Show Different In Vitro Neurotoxicity and Mice Behaviour Impairment

N-Ethylhexedrone (NEH) and buphedrone (Buph) are emerging synthetic cathinones (SC) with limited information about their detrimental effects within central nervous system. Objectives: To distinguish mice behavioural changes by NEH and Buph and validate their differential harmful impact on human neurons and microglia. In vivo safety data showed the typical induced behaviour of excitation and stereotypies with 4-64 mg/kg, described for other SC. Buph additionally produced jumping and aggressiveness signs, while NEH caused retropulsion and circling. Transient reduction in body-weight gain was obtained with NEH at 16 mg/kg and induced anxiolytic-like behaviour mainly with Buph. Both drugs generated place preference shift in mice at 4 and 16 mg/kg, suggestive of abuse potential. In addition, mice withdrawn NEH displayed behaviour suggestive of depression, not seen with Buph. When tested at 50-400 μM in human nerve cell lines, NEH and Buph caused neuronal viability loss at 100 μM, but only NEH produced similar results in microglia, indicating different cell susceptibilities. NEH mainly induced microglial late apoptosis/necrosis, while Buph caused early apoptosis. NEH was unique in triggering microglia shorter/thicker branches indicative of cell activation, and more effective in increasing microglial lysosomal biogenesis (100 μM vs. 400 μM Buph), though both produced the same effect on neurons at 400 μM. These findings indicate that NEH and Buph exert neuro-microglia toxicities by distinct mechanisms and highlight NEH as a specific inducer of microglia activation. Buph and NEH showed in vivo/in vitro neurotoxicities but enhanced specific NEH-induced behavioural and neuro-microglia dysfunctionalities pose safety concerns over that of Buph.

New mechanism of neuroinflammation in Alzheimer's disease: The activation of NLRP3 inflammasome mediated by gut microbiota

Alzheimer's disease (AD) is a central degenerative disease characterized by cognitive impairment. Polymerization of β-amyloid has been reported to cause the entanglement of nerve cells, leading to the progressive loss of nerve cells. Accumulative studies have confirmed the important roles of neuroinflammation in the development of AD. In this study, the gut microbiota from AD patients were transplanted into APP/PS1 double transgenic mice. As a result, the expression of NLRP3 was increased in the intestinal tract of mice, and the expression levels of inflammatory factors in peripheral blood were also increased. Consistently, the cognitive impairment was more severe in mice receiving gut microbiota from AD patients than those did not, with activation of microglia in the central hippocampus of mice, and increased expression of neuroinflammatory factors. In APP/PS1 mice transplanted with gut microbiota from AD patients, transplantation of healthy human gut microbiota or oral administration of minocycline was further used to improve the composition of gut microbiota. Consequently, the intestinal expression of NLRP3 was down-regulated, the cognitive ability of mice was improved, the activation of microglia in central hippocampus was suppressed and the expression of neuroinflammatory factors was also down-regulated. After transplantation of gut microbiota from AD patients in C57BL/6 mice, the intestinal expression of NLRP3 was up-regulated. Although the cognitive ability of mice was not significantly changed, the microglia in the hippocampus of mice were still activated and the expression of inflammatory factors was up-regulated. In this study, we found that gut microbiota in AD patients could induce the activation of NLRP3 inflammasome in the intestinal tract of mice, subsequently causing the release of inflammatory factors. The absorption and circulation of inflammatory factors through the intestinal tract could further aggravate the inflammation in the nervous tissues and the activation of microglia. Therefore, improving the composition of gut microbiota in AD patients can further attenuate neuroinflammation, which is considered as a novel idea for AD treatment.

Experimental Study Using Multiple Strains of Prion Disease in Cattle Reveals an Inverse Relationship between Incubation Time and Misfolded Prion Accumulation, Neuroinflammation, and Autophagy

Proteinopathies result from aberrant folding and accumulation of specific proteins. Currently, there is a lack of knowledge about the factors that influence disease progression, making this a key challenge for the development of therapies for proteinopathies. Because of the similarities between transmissible spongiform encephalopathies (TSEs) and other protein misfolding diseases, TSEs can be used to understand other proteinopathies. Bovine spongiform encephalopathy (BSE) is a TSE that occurs in cattle and can be subdivided into three strains: classic BSE and atypical BSEs (H and L types) that have shorter incubation periods. The NACHT, LRR, and PYD domains-containing protein 3 inflammasome is a critical component of the innate immune system that leads to release of IL-1β. Macroautophagy is an intracellular mechanism that plays an essential role in protein clearance. In this study, the retina was used as a model to investigate the relationship between disease incubation period, prion protein accumulation, neuroinflammation, and changes in macroautophagy. We demonstrate that atypical BSEs present with increased prion protein accumulation, neuroinflammation, and decreased autophagy. This work suggests a relationship between disease time course, neuroinflammation, and the autophagic stress response, and may help identify novel therapeutic biomarkers that can delay or prevent the progression of proteinopathies.

Impact of HMGB1, RAGE, and TLR4 in Alzheimer's Disease (AD): From Risk Factors to Therapeutic Targeting

Alzheimer’s disease (AD) is a devastating neurodegenerative disorder and a leading cause of dementia, with accumulation of amyloid-beta (Aβ) and neurofibrillary tangles (NFTs) as defining pathological features. AD presents a serious global health concern with no cure to date, reflecting the complexity of its pathogenesis. Recent evidence indicates that neuroinflammation serves as the link between amyloid deposition, Tau pathology, and neurodegeneration. The high mobility group box 1 (HMGB1) protein, an initiator and activator of neuroinflammatory responses, has been involved in the pathogenesis of neurodegenerative diseases, including AD. HMGB1 is a typical damage-associated molecular pattern (DAMP) protein that exerts its biological activity mainly through binding to the receptor for advanced glycation end products (RAGE) and toll-like receptor 4 (TLR4). RAGE and TLR4 are key components of the innate immune system that both bind to HMGB1. Targeting of HMGB1, RAGE, and TLR4 in experimental AD models has demonstrated beneficial effects in halting AD progression by suppressing neuroinflammation, reducing Aβ load and production, improving spatial learning, and inhibiting microglial stimulation. Herein, we discuss the contribution of HMGB1 and its receptor signaling in neuroinflammation and AD pathogenesis, providing evidence of its beneficial effects upon therapeutic targeting.

Clinical Significance of High-Mobility Group Box 1 Protein (HMGB1) and Nod-Like Receptor Protein 3 (NLRP3) in Patients with Ulcerative Colitis

Background

The aim of this study was to investigate the clinical significance of NLRP3 and HMGB1 in patients with active ulcerative colitis.

Material/Methods

This was a prospective observational study which included a total of 62 cases with active ulcerative colitis during January 2017 to December 2018. The patients were divided into a mild/moderate group or a severe group according to Sutherland Disease Activity Index (DAI) score. Clinical activity index and endoscopic index were used to determine the severity of UC. Serum levels of NLRP3, HMGB1, endothelin-1, IL-1β, and TNF-α were determined by enzyme-linked immunosorbent assay (ELISA).

Results

Sutherland DAI score, clinical activity index, and endoscopic index were all significantly higher in severe patients than in the mild/moderate group. NLRP3, HMGB1, endothelin-1, IL-1β, and TNF-α were significantly higher in severe UC patients. NLRP3 level was positively correlated with HMGB1, ET-1, IL-1β, and TNF-α levels. Both NLRP3 and HMGB1 were positively correlated with Sutherland DAI score, clinical activity index, and endoscopic index.

Conclusions

Both serum NLRP3 and HMGB1 were elevated in UC patients, and the serum levels of NLRP3 were positively correlated with serum levels of HMGB1, ET-1, IL-1β, and TNF-α, as well as severity of UC patients.

The Potential Markers of Circulating microRNAs and long non-coding RNAs in Alzheimer's Disease

Alzheimer’s disease (AD) is a neurodegenerative disorder and one of the leading causes of disability and mortality in the late life with no curative treatment currently. Thus, it is urgently to establish sensitive and non-invasive biomarkers for AD diagnosis, particularly in the early stage. Recently, emerging number of microRNAs (miRNAs) and long-noncoding RNAs (lncRNAs) are considered as effective biomarkers in various diseases as they possess characteristics of stable, resistant to RNAase digestion and many extreme conditions in circulatory fluid. This review highlights recent advances in the identification of the aberrantly expressed miRNAs and lncRNAs in circulatory network for detection of AD. We summarized the abnormal expressed miRNAs in blood and cerebrospinal fluid (CSF), and detailed discussed the functions and molecular mechanism of serum or plasma miRNAs-miR-195, miR-155, miR-34a, miR-9, miR-206, miR-125b and miR-29 in the regulation of AD progression. In addition, we also elaborated the role of circulating lncRNA major including beta-site APP cleaving enzyme 1 (BACE1) and its antisense lncRNA BACE1-AS in AD pathological advancement. In brief, confirming the aberrantly expressed circulating miRNAs and lncRNAs will provide an effective testing tools for treatment of AD in the future.

Cathepsin-sensitive nanoscale drug delivery systems for cancer therapy and other diseases

Cathepsins are an important category of enzymes that have attracted great attention for the delivery of drugs to improve the therapeutic outcome of a broad range of nanoscale drug delivery systems. These proteases can be utilized for instance through actuation of polymer-drug conjugates (e.g., triggering the drug release) to bypass limitations of many drug candidates. A substantial amount of work has been witnessed in the design and the evaluation of Cathepsin-sensitive drug delivery systems, especially based on the tetra-peptide sequence (Gly-Phe-Leu-Gly, GFLG) which has been extensively used as a spacer that can be cleaved in the presence of Cathepsin B. This Review Article will give an in-depth overview of the design and the biological evaluation of Cathepsin-sensitive drug delivery systems and their application in different pathologies including cancer before discussing Cathepsin B-cleavable prodrugs under clinical trials.

Phenotypic Effects of Wild-Type and Mutant SOD1 Expression in N9 Murine Microglia at Steady State, Inflammatory and Immunomodulatory Conditions

Accumulation of mutated superoxide dismutase 1 (mSOD1) in amyotrophic lateral sclerosis (ALS) involves injury to motor neurons (MNs), activation of glial cells and immune unbalance. However, neuroinflammation, besides its detrimental effects, also plays beneficial roles in ALS pathophysiology. Therefore, the targeting of microglia to modulate the release of inflammatory neurotoxic mediators and their exosomal dissemination, while strengthening cell neuroprotective properties, has gained growing interest. We used the N9 microglia cell line to identify phenotype diversity upon the overexpression of wild-type (WT; hSOD1WT) and mutated G93A (hSOD1G93A) protein. To investigate how each transduced cell respond to an inflammatory stimulus, N9 microglia were treated with lipopolysaccharide (LPS). Glycoursodeoxycholic acid (GUDCA) and dipeptidyl vinyl sulfone (VS), known to exert neuroprotective properties, were tested for their immunoregulatory properties. Reduced Fizz1, IL-10 and TLR4 mRNAs were observed in both transduced cells. However, in contrast with hSOD1WT-induced decreased of inflammatory markers, microglia transduced with hSOD1G93A showed upregulation of pro-inflammatory (TNF-α/IL-1β/HMGB1/S100B/iNOS) and membrane receptors (MFG-E8/RAGE). Importantly, their derived exosomes were enriched in HMGB1 and SOD1. When inflammatory-associated miRNAs were evaluated, increased miR-146a in cells with overexpressed hSOD1WT was not recapitulated in their exosomes, whereas hSOD1G93A triggered elevated exosomal miR-155/miR-146a, but no changes in cells. LPS stimulus increased M1/M2 associated markers in the naïve microglia, including MFG-E8, miR-155 and miR-146a, whose expression was decreased in both hSOD1WT and hSOD1G93A cells treated with LPS. Treatment with GUDCA or VS led to a decrease of TNF-α, IL-1β, HMGB1, S100B and miR-155 in hSOD1G93A microglia. Only GUDCA was able to increase cellular IL-10, RAGE and TLR4, together with miR-21, while decreased exosomal miR-155 cargo. Conversely, VS reduced MMP-2/MMP-9 activation, as well as upregulated MFG-E8 and miR-146a, while producing miR-21 shuttling into exosomes. The current study supports the powerful role of overexpressed hSOD1WT in attenuating M1/M2 activation, and that of hSOD1G93A in switching microglia from the steady state into a reactive phenotype with low responsiveness to stimuli. This work further reveals GUDCA and VS as promising modulators of microglia immune response by eliciting common and compound-specific molecular mechanisms that may promote neuroregeneration.

MicroRNAs and the Genetic Nexus of Brain Aging, Neuroinflammation, Neurodegeneration, and Brain Trauma

Aging is a complex and integrated gradual deterioration of cellular activities in specific organs of the body, which is associated with increased mortality. This deterioration is the primary risk factor for major human pathologies, including cancer, diabetes, cardiovascular disorders, neurovascular disorders, and neurodegenerative diseases. There are nine tentative hallmarks of aging. In addition, several of these hallmarks are increasingly being associated with acute brain injury conditions. In this review, we consider the genes and their functional pathways involved in brain aging as a means of developing new strategies for therapies targeted to the neuropathological processes themselves, but also as targets for many age-related brain diseases. A single microRNA (miR), which is a short, non-coding RNA species, has the potential for targeting many genes simultaneously and, like practically all other cellular processes, genes associated with many features of brain aging and injury are regulated by miRs. We highlight how certain miRs can mediate deregulation of genes involved in neuroinflammation, acute neuronal injury and chronic neurodegenerative diseases. Finally, we review the recent progress in the development of effective strategies to block specific miR functions and discuss future approaches with the prediction that anti-miR drugs may soon be used in the clinic.

Targeting NLRP3 Inflammasome in the Treatment of CNS Diseases

Central nervous system (CNS) is one of the largest killers of people’s health all over the world. The overactivation of the immune and inflammatory responses is considered as an important factor, contributing to the pathogenesis and progression of CNS disorders. Among all kinds of immune and inflammatory reaction, the inflammasome, a complex of proteins, has been drawn increasingly attention to by researchers. The initiation and activation of the inflammasome is involved in the onset of various kinds of diseases. The NLRP3 inflammasome, the most studied member of the inflammasome, is closely associated with many kinds of CNS disorders. Here in this review, the roles of the NLRP3 inflammasome in the pathogenesis and progression of several well-known CNS diseases would be discussed, including cerebrovascular diseases, neurodegenerative diseases, multiple sclerosis, depression as well as other CNS disorders. In addition, several therapeutic strategies targeting on the NLRP3 inflammasome for the treatment of CNS disorders would be described in this review.

Secretome from SH-SY5Y APPSwe cells trigger time-dependent CHME3 microglia activation phenotypes, ultimately leading to miR-21 exosome shuttling

Exosome-mediated intercellular communication has been increasingly recognized as having a broad impact on Alzheimer's disease (AD) pathogenesis. Still, limited information exists regarding their "modus operandi", as it critically depends on exosomal cargo, environmental context and target cells. Therefore, a more thorough understanding of the role of exosomes from different cell types as mediators of neuroinflammation in AD context is a decisive step to open avenues for innovative and efficient therapies. In this study, we demonstrate that SH-SY5Y cells transfected with the Swedish mutant of APP₆₉₅ (SH_Swe) remarkably express increased inflammatory markers, combined with higher APP and Aβ_1-40 production, when compared to naïve SH-SY5Y (SH) cells. Although exerting an early clearance effect on extracellular APP and Aβ accumulation when in co-culture with SH_Swe cells, human CHME3 microglia gradually lose such property, and express both pro-inflammatory (iNOS, IL-1β, TNF-α, MHC class II, IL-6) and pro-resolving genes (IL-10 and Arginase 1), while also evidence increased senescence-associated β-galactosidase activity. Interestingly, upregulation of inflammatory-associated miRNA (miR)-155, miR-146a and miR-124 by SH_Swe secretome shows to be time-dependent and to inversely correlate with their respective targets (SOCS-1, IRAK1 and C/EBP-α). We report that microglia also internalize exosomes released from SH_Swe cells, which are enriched in miR-155, miR-146a, miR-124, miR-21 and miR-125b and recapitulate the cells of origin. Furthermore, we show that SH_Swe-derived exosomes are capable of inducing acute and delayed microglial upregulation of TNF-α, HMGB1 and S100B pro-inflammatory markers, from which only S100B is found on their derived exosomes. Most importantly, our data reveal that miR-21 is a consistent biomarker that is found not only in SH_Swe cells and in their released exosomes, but also in the recipient CHME3 microglia and derived exosomes. This work contributes to the increased understanding of neuron-microglia communication and exosome-mediated neuroinflammation in AD, while highlights miR-21 as a promising biomarker/target for therapeutic intervention.

Key Aging-Associated Alterations in Primary Microglia Response to Beta-Amyloid Stimulation

Alzheimer's disease (AD) is characterized by a progressive cognitive decline and believed to be driven by the self-aggregation of amyloid-β (Aβ) peptide into oligomers and fibrils that accumulate as senile plaques. It is widely accepted that microglia-mediated inflammation is a significant contributor to disease pathogenesis; however, different microglia phenotypes were identified along AD progression and excessive Aβ production was shown to dysregulate cell function. As so, the contribution of microglia to AD pathogenesis remains to be elucidated. In this study, we wondered if isolated microglia cultured for 16 days in vitro (DIV) would react differentially from the 2 DIV cells upon treatment with 1000 nM Aβ_1-42 for 24 h. No changes in cell viability were observed and morphometric alterations associated to microglia activation, such as volume increase and process shortening, were obvious in 2 DIV microglia, but less evident in 16 DIV cells. These cells showed lower phagocytic, migration and autophagic properties after Aβ treatment than the 2 DIV cultured microglia. Reduced phagocytosis may derive from increased CD33 expression, reduced triggering receptor expressed on myeloid cells 2 (TREM2) and milk fat globule-EGF factor 8 protein (MFG-E8) levels, which were mainly observed in 16 DIV cells. Activation of inflammatory mediators, such as high mobility group box 1 (HMGB1) and pro-inflammatory cytokines, as well as increased expression of Toll-like receptor 2 (TLR2), TLR4 and fractalkine/CX3C chemokine receptor 1 (CX3CR1) cell surface receptors were prominent in 2 DIV microglia, while elevation of matrix metalloproteinase 9 (MMP9) was marked in 16 DIV cells. Increased senescence-associated β-galactosidase (SA-β-gal) and upregulated miR-146a expression that were observed in 16 DIV cells showed to increase by Aβ in 2 DIV microglia. Additionally, Aβ downregulated miR-155 and miR-124, and reduced the CD11b+ subpopulation in 2 DIV microglia, while increased the number of CD86+ cells in 16 DIV microglia. Simultaneous M1 and M2 markers were found after Aβ treatment, but at lower expression in the in vitro aged microglia. Data show key-aging associated responses by microglia when incubated with Aβ, with a loss of reactivity from the 2 DIV to the 16 DIV cells, which course with a reduced phagocytosis, migration and lower expression of inflammatory miRNAs. These findings help to improve our understanding on the heterogeneous responses that microglia can have along the progression of AD disease and imply that therapeutic approaches may differ from early to late stages.

Exosomes from NSC-34 Cells Transfected with hSOD1-G93A Are Enriched in miR-124 and Drive Alterations in Microglia Phenotype

Amyotrophic lateral sclerosis (ALS) is a fatal adult-onset neurodegenerative disorder affecting motor neurons (MNs). Evidences indicate that ALS is a non-cell autonomous disease in which glial cells participate in both disease onset and progression. Exosomal transfer of mutant copper-zinc superoxide dismutase 1 (mSOD1) from cell-to-cell was suggested to contribute to disease dissemination. Data from our group and others showed that exosomes from activated cells contain inflammatory-related microRNAs (inflamma-miRNAs) that recapitulate the donor cell. While glia-derived exosomes and their effects in neurons have been addressed by several studies, only a few investigated the influence of motor neuron (MN)-derived exosomes in other cell function, the aim of the present study. We assessed a set of inflamma-miRs in NSC-34 MN-like cells transfected with mutant SOD1(G93A) and extended the study into their derived exosomes (mSOD1 exosomes). Then, the effects produced by mSOD1 exosomes in the activation and polarization of the recipient N9 microglial cells were investigated. Exosomes in coculture with N9 microglia and NSC-34 cells [either transfected with either wild-type (wt) human SOD1 or mutant SOD1(G93A)] showed to be transferred into N9 cells. Increased miR-124 expression was found in mSOD1 NSC-34 cells and in their derived exosomes. Incubation of mSOD1 exosomes with N9 cells determined a sustained 50% reduction in the cell phagocytic ability. It also caused a persistent NF-kB activation and an acute generation of NO, MMP-2, and MMP-9 activation, as well as upregulation of IL-1β, TNF-α, MHC-II, and iNOS gene expression, suggestive of induced M1 polarization. Marked elevation of IL-10, Arginase 1, TREM2, RAGE, and TLR4 mRNA levels, together with increased miR-124, miR-146a, and miR-155, at 24 h incubation, suggest the switch to mixed M1 and M2 subpopulations in the exosome-treated N9 microglial cells. Exosomes from mSOD1 NSC-34 MNs also enhanced the number of senescent-like positive N9 cells. Data suggest that miR-124 is translocated from the mSOD1 MNs to exosomes, which determine early and late phenotypic alterations in the recipient N9-microglial cells. In conclusion, modulation of the inflammatory-associated miR-124, in mSOD1 NSC-34 MNs, with potential benefits in the cargo of their exosomes may reveal a promising therapeutic strategy in halting microglia activation and associated effects in MN degeneration.

Chitinase1 contributed to a potential protection via microglia polarization and Aβ oligomer reduction in D-galactose and aluminum-induced rat model with cognitive impairments

Chitinase activity is increased in Alzheimer's disease (AD). However, the role of chitinase1 in AD is unknown. We investigated the effects of chitinase1 on Alzheimer's pathology and microglia function. Artificial chitinase1 and chitinase inhibitor (chitinase-IN-2) were used to determine the effects of chitinase1 on inflammatory factors and β-amyloid (Aβ) oligomers deposition in D-galactose/AlCl₃-induced rat model with cognitive impairments. Aβ-treated N9 microglia cells were analyzed to further verify whether the changes in inflammatory factors following chitinase1 treatment were associated with microglia alternative activation. Our data displayed that the activity of chitinase1 was both improved in D-galactose/AlCl₃-injected rats and Aβ-pretreated microglia. Moreover, there was an improvement in cognitive function in chitinase1-treated AD rats. Furthermore, anti-inflammation factors (Arginase 1, Arg-1, mannose receptor type C 1, MRC1/CD206) were increased and pro-inflammation factors (tumor necrosis factor alpha, TNFα, interleukin 1 beta, IL-1β) were decreased in D-galactose/AlCl₃-induced AD rats with chitinase1 treatment. A higher level of M2 markers (Arg-1, MRC1/CD206) and a lower level of classic M1 markers (TNFa, IL-1β) were obtained in Aβ-pretreated N9 cells with chitinase1, suggesting that chitinase1 polarized the microglia into an anti-AD M2 phenotype. We also detected that chitnase1 could weaken the deposition of Aβ oligomers in the brain of D-galactose/ AlCl_3-induced AD rats. In conclusion, Chitinase1 might exert protective effects against AD by polarizing microglia to an M2 phenotype and resisting Aβ oligomer deposition.

Exploring New Inflammatory Biomarkers and Pathways during LPS-Induced M1 Polarization

Identification of mediators triggering microglia activation and transference of noncoding microRNA (miRNA) into exosomes are critical to dissect the mechanisms underlying neurodegeneration. We used lipopolysaccharide- (LPS-) induced N9 microglia activation to explore new biomarkers/signaling pathways and to identify inflammatory miRNA (inflamma-miR) in cells and their derived exosomes. Upregulation of iNOS and MHC-II (M1-markers) and downregulation of arginase 1, FIZZ1 (M2-markers), and CX3CR1 (M0/M2 polarization) confirmed the switch of N9 LPS-treated cells into the M1 phenotype, as described for macrophages/microglia. Cells showed increased proliferation, activated TLR4/TLR2/NF-κB pathway, and enhanced phagocytosis, further corroborated by upregulated MFG-E8. We found NLRP3-inflammasome activation in these cells, probably accounting for the increased extracellular content of the cytokine HMGB1 and of the MMP-9 we have observed. We demonstrate for the first time that the inflamma-miR profiling (upregulated miR-155 and miR-146a plus downregulated miR-124) in M1 polarized N9 cells, noticed by others in activated macrophages/microglia, was replicated in their derived exosomes, likely regulating the inflammatory response of recipient cells and dissemination processes. Data show that LPS-treated N9 cells behave like M1 polarized microglia/macrophages, while providing new targets for drug discovery. In particular, the study yields novel insights into the exosomal circulating miRNA during neuroinflammation important for emerging therapeutic approaches targeting microglia activation.