C/EBPβ is a key transcription factor for APOE and preferentially mediates ApoE4 expression in Alzheimer's disease

Immunotherapy against tau fragment diminishes AD pathology, improving synaptic function and cognition

BACKGROUND

Asparagine endopeptidase (AEP) is implicated in the pathogenesis of Alzheimer's disease (AD) by cleaving Tau at residue N368, accelerating its hyperphosphorylation and aggregation. The Tau N368/t-Tau ratio in cerebrospinal fluid (CSF) serves as a superior biomarker compared to established biomarkers (p-Tau 181/217) for correlating with tau pathology and synaptic dysfunction in patients with AD, highlighting its diagnostic and therapeutic potential.

METHODS

We evaluated the therapeutic efficacy of a Tau N368-specific antibody in two mouse models: Tau P301S (tauopathy) and 3xTg (AD with Aβ/tau pathology). We conducted chronic intraperitoneal administration of the antibody to evaluate its effects on tau aggregation, synaptic integrity, and cognitive function. Neuropathological changes, synaptic plasticity (through electrophysiology), and behavioral outcomes were analyzed alongside Aβ pathology and neuroinflammation in 3xTg mice.

RESULTS

Treatment with the anti-Tau N368 antibody significantly diminished neurofibrillary tangles (NFTs) formed of hyperphosphorylated/truncated Tau in both models. Clearance of Tau restored BDNF/TrkB neurotrophic signaling, improved synaptic plasticity, and alleviated cognitive deficits. In 3xTg mice, this treatment also reduced Aβ deposition and neuroinflammation, resulting in enhanced learning and memory. Notably, the antibody's effectiveness in alleviating both tau and Aβ pathologies indicates a potential interaction between these pathways.

CONCLUSIONS

Targeting Tau N368 through immunotherapy alleviates tau-driven neurodegeneration, restores synaptic function, and improves accompanying Aβ pathology in AD models. Our results confirmed that Tau N368 is an exceptional biomarker and a promising therapeutic target, disrupting AD progression by addressing tau aggregation and its downstream effects.

Impaired ApoB secretion triggers enhanced secretion of ApoE to maintain triglyceride homeostasis in hepatoma cells

Apolipoprotein B (ApoB) is essential for the assembly and secretion of triglyceride (TG)-rich VLDL particles, and its dysfunction is linked to metabolic disorders, including dyslipidemia and liver steatosis. However, less attention has been paid to whether and how other apolipoproteins play redundant or compensatory roles when the ApoB function is compromised. Here, we investigated the effects of microsomal triglyceride transfer protein (MTP), which mediates lipidation of nascent ApoB, on ApoE function. We observed a paradoxical increase in ApoE secretion resulting from increased expression in MTP inhibitor (MTPi)-treated human hepatoma cells. This phenotype was recapitulated in APOB-knockout cells and was associated with impaired ApoB secretion. While MTP-dependent transfer of neutral lipids is dispensable for ApoE secretion, TG biosynthesis, redundantly catalyzed by DGAT1 and DGAT2, is required for efficient ApoE secretion in hepatoma cells. ApoE colocalizes with lipid droplets near the Golgi apparatus and mediates TG export in an ApoB-independent fashion. We found that simultaneous inhibition of both ApoE and ApoB, but not inhibition of either alone, led to TG accumulation in hepatoma cells, indicating that both proteins function redundantly to control TG content. Validation studies in primary human hepatocytes (PHHs) demonstrated DGAT2-dependent secretion of ApoE. While MTPi treatment did not elevate ApoE secretion, it induced increased sialylation of ApoE in the supernatants of PHHs. These results show that enhanced ApoE secretion compensates for the impaired ApoB function to maintain the lipid homeostasis, providing an alternative route to modulate lipid turnover in hepatoma cells.

New mechanisms highlight the complex relationship of Apolipoprotein E and tau pathogenesis

A rare variant of Apolipoprotein E3 with neuroprotective properties has been identified in autosomal-dominant Alzheimer's disease. In this issue of Neuron, Chen et al.1 show that direct interaction between this variant and tau blocks tau pathogenesis in rodent models.

ApoE3 R136S binds to Tau and blocks its propagation, suppressing neurodegeneration in mice with Alzheimer's disease

PSEN1 E280A carrier for the APOE3 Christchurch variant (R136S) is protected against Alzheimer's disease (AD) symptoms with a distinct anatomical pattern of Tau pathology. However, the molecular mechanism accounting for this protective effect remains incompletely understood. Here, we show that the ApoE3 R136S mutant strongly binds to Tau and reduces its uptake into neurons and microglia compared with ApoE3 wild type (WT), diminishing Tau fragmentation by asparagine endopeptidase (AEP), proinflammatory cytokines by Tau pre-formed fibrils (PFFs) or β-amyloid (Aβ), and neurotoxicity. Further, ApoE3 R136S demonstrates more robust effects in attenuating AEP activation and Tau PFF spreading in the brains of both 5xFAD and Tau P301S mice than in ApoE3 WT, leading to improved cognitive functions. Thus, our findings support the idea that ApoE3 R136S strongly binds Tau and decreases its cellular uptake, abrogating Tau pathology propagation in AD brains.

From Genetics to Neuroinflammation: The Impact of ApoE4 on Microglial Function in Alzheimer's Disease

Alzheimer's disease (AD) is a debilitating neurodegenerative disorder marked by progressive cognitive decline and memory loss, impacting millions of people around the world. The apolipoprotein E4 (ApoE4) allele is the most prominent genetic risk factor for late-onset AD, dramatically increasing disease susceptibility and accelerating onset compared to its isoforms ApoE2 and ApoE3. ApoE4's unique structure, which arises from single-amino-acid changes, profoundly alters its function. This review examines the critical interplay between ApoE4 and microglia-the brain's resident immune cells-and how this relationship contributes to AD pathology. We explore the molecular mechanisms by which ApoE4 modulates microglial activity, promoting a pro-inflammatory state, impairing phagocytic function, and disrupting lipid metabolism. These changes diminish microglia's ability to clear amyloid-beta peptides, exacerbating neuroinflammation and leading to neuronal damage and synaptic dysfunction. Additionally, ApoE4 adversely affects other glial cells, such as astrocytes and oligodendrocytes, further compromising neuronal support and myelination. Understanding the ApoE4-microglia axis provides valuable insights into AD progression and reveals potential therapeutic targets. We discuss current strategies to modulate ApoE4 function using small molecules, antisense oligonucleotides, and gene editing technologies. Immunotherapies targeting amyloid-beta and ApoE4, along with neuroprotective approaches to enhance neuronal survival, are also examined. Future directions highlight the importance of personalized medicine based on individual ApoE genotypes, early biomarker identification for risk assessment, and investigating ApoE4's role in other neurodegenerative diseases. This review emphasizes the intricate connection between ApoE4 and microglial dysfunction, highlighting the necessity of targeting this pathway to develop effective interventions. Advancing our understanding in this area holds promise for mitigating AD progression and improving outcomes for those affected by this relentless disease.

C/EBPβ in Alzheimer's disease: An integrative regulator of pathological mechanisms

Alzheimer's disease (AD) stands as one of the most prevalent neurodegenerative disorders, characterized by a progressive decline in cognitive function, neuroinflammation, amyloid-beta (Aβ) plaques, and neurofibrillary tangles (NFTs). With the global aging population, the incidence of AD continues to rise, yet current therapeutic strategies remain limited in their ability to significantly alleviate cognitive impairments. Therefore, a deeper understanding of the molecular mechanisms underlying AD is imperative for the development of more effective treatments. In recent years, the transcription factor C/EBPβ has emerged as a pivotal regulator in several pathological processes of AD, including neuroinflammation, lipid metabolism, Aβ processing, and tau phosphorylation. Through intricate post-translational modifications, C/EBPβ modulates these processes and may influence the progression of AD on multiple fronts. This review systematically explores the multifaceted roles of C/EBPβ in the pathogenesis of AD, delving into its crucial involvement in neuroinflammation, Aβ production, tau pathology, and lipid metabolism dysregulation. Furthermore, we critically assess therapeutic strategies targeting C/EBPβ, examining the challenges and opportunities in regulating this factor. By synthesizing the latest research findings, we offer a more comprehensive understanding of the role of C/EBPβ in AD and discuss its potential as a therapeutic intervention target.

Convergent effects of synthetic glucocorticoid dexamethasone and amyloid beta in human olfactory neurosphere-derived cells

Stressful life events and glucocorticoid (stress) hormones appear to increase the risk of Alzheimer's disease and hasten its progression, but the reasons for this remain unclear. One potential explanation is that when amyloid β (Aβ) pathology is accumulating in the preclinical disease stage, glucocorticoid receptor signalling during stressful events exacerbates cellular dysfunction caused by Aβ. Alternatively, Aβ may disrupt glucocorticoid receptor signalling. To explore these possibilities, we investigated whether the synthetic glucocorticoid dexamethasone and Aβ have overlapping effects on the cellular proteome and whether Aβ influences canonical glucocorticoid receptor function. Human olfactory neurosphere-derived (ONS) cells, collected from the olfactory mucosa of six adult donors, were treated with soluble Aβ40 or Aβ42 followed by dexamethasone. Proteins were quantified by mass spectrometry. After 32 h treatment, Aβ40 and Aβ42 both induced profound changes in innate immunity-related proteins. After 72 h, Aβ42 formed widespread aggregates and induced few proteomic changes, whereas Aβ40 remained soluble and altered expression of mitochondrial and innate immunity-related proteins. ONS cells revealed overlapping impacts of Aβ40 and dexamethasone, with 23 proteins altered by both treatments. For 16 proteins (including eight mitochondrial proteins) dexamethasone counteracted the effects of Aβ40. For example, caspase 4 and methylmalonate-semialdehyde dehydrogenase were increased by Aβ40 and decreased by dexamethasone. Consistent with this finding, Aβ40 increased, but dexamethasone decreased, ONS cell proliferation. For seven proteins, including superoxide dismutase [Mn] mitochondrial, dexamethasone exacerbated the effects of Aβ40. For some proteins, including complement C3, the effects of dexamethasone differed depending on whether Aβ40 was present or absent. Neither Aβ species influenced glucocorticoid receptor nuclear translocation. Overall, this study revealed that glucocorticoid receptor signalling modifies the intracellular effects of Aß40, counteracting some effects and exacerbating others. It suggests that cellular mechanisms through which glucocorticoid receptor signalling influences Alzheimer's disease risk/progression are complex and determined by the balance of beneficial and detrimental glucocorticoid effects.

Exploring TNFR1: from discovery to targeted therapy development

This review seeks to elucidate the therapeutic potential of tumor necrosis factor receptor 1 (TNFR1) and enhance our comprehension of its role in disease mechanisms. As a critical cell-surface receptor, TNFR1 regulates key signaling pathways, such as nuclear factor kappa-B (NF-κB) and mitogen-activated protein kinase (MAPK), which are associated with pro-inflammatory responses and cell death. The intricate regulatory mechanisms of TNFR1 signaling and its involvement in various diseases, including inflammatory disorders, infectious diseases, cancer, and metabolic syndromes, have attracted increasing scholarly attention. Given the potential risks associated with targeting tumor necrosis factor-alpha (TNF-α), selective inhibition of the TNFR1 signaling pathway has been proposed as a promising strategy to reduce side effects and enhance therapeutic efficacy. This review emphasizes the emerging field of targeted therapies aimed at selectively modulating TNFR1 activity, identifying promising therapeutic strategies that exploit TNFR1 as a drug target through an evaluation of current clinical trials and preclinical studies. In conclusion, this study contributes novel insights into the biological functions of TNFR1 and presents potential therapeutic strategies for clinical application, thereby having substantial scientific and clinical significance.

NLRP3 inflammasome-modulated angiogenic function of EPC via PI3K/ Akt/mTOR pathway in diabetic myocardial infarction

BACKGROUND

Inflammatory diseases impair the reparative properties of endothelial progenitor cells (EPC); however, the involvement of diabetes in EPC dysfunction associated with myocardial infarction (MI) remains unknown.

METHODS

A model was established combining high-fat diet (HFD)/streptozotocin (STZ)-induced diabetic mice with myocardial infarction. The therapeutic effects of transplanted wild-type EPC, Nlrp3 knockout EPC, and Nlrp3 overexpression EPC were evaluated. Chip and Luciferase assay revealed CEBPB regulated the transcriptional expression of Nlrp3 as a transcription factor in EPC stimulated by high glucose (HG) or advanced glycation end products (AGEs). CO-IP results suggested that USP14 selectively suppressed NLRP3 degradation. KEGG enrichment revealed PI3K/ Akt/mTOR signaling showed striking significance in the entire pathway.

RESULTS

In our study, wild-type, Nlrp3 knockout and Nlrp3 overexpressed EPC, intracardiac injections effectively improved cardiac function, increased angiogenesis, and reduced infarct size in mice with myocardial infarction. However, in the HFD/STZ-induced diabetic mice model combined with myocardial infarction, Nlrp3 knockout EPC significantly restored angiogenic capacity. Mechanically, CEBPB regulated the transcriptional level of Nlrp3 as a transcription factor in EPC. Meanwhile, we found that USP14 selectively suppressed NLRP3 protein degradation through the USP motif on the NACHT domain in mediating inflammasome activation. Cardiac functional outcomes in recipient mice after intramyocardial injection of shNlrp3 EPC overexpressing CEBPB or USP14 validated the modulation of EPC function by regulating Nlrp3 transcription or post-translational modification. Furthermore, KEGG enrichment and validation at the protein levels revealed PI3K/ Akt/mTOR cascade might be a downstream signal for NLRP3 inflammasome.

CONCLUSION

Our study provides a new understanding of how diabetes affected progenitor cell-mediated cardiac repair and identifies NLRP3 as a new therapeutic target for improving myocardial infarction repair in inflammatory diseases.

Advancements and challenges in mouse models of Alzheimer's disease

Alzheimer's disease (AD) poses a significant health challenge worldwide, and the development of effective treatments necessitates a comprehensive understanding of its pathophysiology. Mouse models have been instrumental in offering insights into the crucial pathogenesis of AD. However, current models rarely recapitulate all aspects of AD pathology in patients; thus, translating the findings from mouse to human clinical trials has proved to be complex. In this review, we outline the development of some prevalently used AD mice, with a particular emphasis on the latest advances in newly generated models. In addition, we discuss the advantages and limitations in mouse models of AD and their applications in blood-based biomarkers. Finally, we speculate on potential future research directions.

N-terminal acetylation of transcription factor LIP induces immune therapy resistance via suppression of PD-L1 expression in non-small cell lung cancer

BACKGROUND

Programmed death-1 (PD-1) checkpoint blockade has revolutionized cancer therapy, yet its clinical success is confined to a subset of patients, underscoring the urgent need to understand the molecular underpinnings of programmed cell death ligand 1 (PD-L1) expression to combat immunotherapy resistance.

METHODS

Employing CRISPR/Cas9 screening, we identified key regulators of PD-L1 in non-small cell lung cancer (NSCLC) cells, focusing on the transcription factor CEBPB and its isoform liver-enriched inhibitory protein (LIP). Through chromatin immunoprecipitation (ChIP) and luciferase reporter assays, we explored the interaction between LIP and basic-helix-loop-helix E22 (BHLHE22) in controlling PD-L1 transcription. We also used immunofluorescence and NBD-CI assays to examine how N-terminal acetylation affects LIP's subcellular localization. The impact of LIP on tumor growth was assessed via subcutaneous tumorigenicity assays, while immunohistochemistry and immunofluorescence were used to analyze LIP-induced alterations in the tumor immune microenvironment.

RESULTS

Our research indicates that CEBPB, particularly its LIP isoform, significantly suppresses PD-L1 expression in NSCLC cells. This suppression is contingent on LIP's N-terminal acetylation by the N-terminal acetyltransferase A complex, which facilitates LIP's nuclear entry and interaction with BHLHE22. This interaction leads to the formation of a co-repressor complex at the PD-L1 promoter, effectively reducing PD-L1 expression and enhancing the tumor immune response.

CONCLUSIONS

Identifying CEBPB, especially the LIP isoform, as a pivotal regulator of PD-L1 expression sheds light on the mechanisms behind PD-1 blockade resistance in NSCLC. Our findings suggest that modulating LIP's function or its molecular interactions might offer a novel approach to boosting the efficacy of immunotherapies.

G-CSF resistance of ELANE-mutant neutropenia depends on SERF1-containing truncated-neutrophil elastase aggregates

Severe congenital neutropenia (SCN) is frequently associated with dominant point mutations in ELANE, the gene encoding neutrophil elastase (NE). Chronic administration of granulocyte colony-stimulating factor (G-CSF) is a first-line treatment of ELANE-mutant (ELANEmut) SCN. However, some ELANEmut patients, including patients with ELANE start codon mutations, do not respond to G-CSF. Here, through directed granulopoiesis of gene-edited isogenic normal and patient-derived iPSCs, we demonstrate that ELANE start codon mutations suffice to induce G-CSF-resistant granulocytic precursor cell death and refractory SCN. ELANE start codon-mutated neutrophil precursors express predominantly nuclear N-terminally truncated alternate NE. Unlike G-CSF-sensitive ELANE mutations that induce endoplasmic reticulum and unfolded protein response stress, we found that the mutation of the ELANE translation initiation codon resulted in NE aggregates and activated proapoptotic aggrephagy, as determined by downregulated BAG1 expression, decreased BAG1/BAG3 ratio, NE colocalization with BAG3, and localized expression of autophagic LC3B. We found that SERF1, an RNA-chaperone protein, known to localize in misfolded protein aggregates in neurodegenerative diseases, was highly upregulated and interacted with cytoplasmic NE of mutant neutrophil precursors. Silencing of SERF1 enhanced survival and differentiation of iPSC-derived neutrophil precursors, restoring their responsiveness to G-CSF. These observations provide a mechanistic insight into G-CSF-resistant ELANEmut SCN, revealing targets for therapeutic intervention.

NLRP3/1-mediated pyroptosis: beneficial clues for the development of novel therapies for Alzheimer's disease

The inflammasome is a multiprotein complex involved in innate immunity that mediates the inflammatory response leading to pyroptosis, which is a lytic, inflammatory form of cell death. There is accumulating evidence that nucleotide-binding domain and leucine-rich repeat pyrin domain containing 3 (NLRP3) inflammasome-mediated microglial pyroptosis and NLRP1 inflammasome-mediated neuronal pyroptosis in the brain are closely associated with the pathogenesis of Alzheimer's disease. In this review, we summarize the possible pathogenic mechanisms of Alzheimer's disease, focusing on neuroinflammation. We also describe the structures of NLRP3 and NLRP1 and the role their activation plays in Alzheimer's disease. Finally, we examine the neuroprotective activity of small-molecule inhibitors, endogenous inhibitor proteins, microRNAs, and natural bioactive molecules that target NLRP3 and NLRP1, based on the rationale that inhibiting NLRP3 and NLRP1 inflammasome-mediated pyroptosis can be an effective therapeutic strategy for Alzheimer's disease.

NLRP3/1-mediated pyroptosis: beneficial clues for the development of novel therapies for Alzheimer's disease

The inflammasome is a multiprotein complex involved in innate immunity that mediates the inflammatory response leading to pyroptosis, which is a lytic, inflammatory form of cell death. There is accumulating evidence that nucleotide-binding domain and leucine-rich repeat pyrin domain containing 3 (NLRP3) inflammasome-mediated microglial pyroptosis and NLRP1 inflammasome-mediated neuronal pyroptosis in the brain are closely associated with the pathogenesis of Alzheimer's disease. In this review, we summarize the possible pathogenic mechanisms of Alzheimer's disease, focusing on neuroinflammation. We also describe the structures of NLRP3 and NLRP1 and the role their activation plays in Alzheimer's disease. Finally, we examine the neuroprotective activity of small-molecule inhibitors, endogenous inhibitor proteins, microRNAs, and natural bioactive molecules that target NLRP3 and NLRP1, based on the rationale that inhibiting NLRP3 and NLRP1 inflammasome-mediated pyroptosis can be an effective therapeutic strategy for Alzheimer's disease.

Thy1-ApoE4/C/EBPβ double transgenic mice act as a sporadic model with Alzheimer's disease

Early onset familial Alzheimer's disease (FAD) with APP, PS1/2 (presenilins) mutation accounts for only a small portion of AD cases, and most are late-onset sporadic. However, majority of AD mouse models are developed to mimic the genetic cause of human AD by overexpressing mutated forms of human APP, PS1/2, and/or Tau protein, though there is no Tau mutation in AD, and no single mouse model recapitulates all aspects of AD pathology. Here, we report Thy1-ApoE4/C/EBPβ double transgenic mouse model that demonstrates key AD pathologies in an age-dependent manner in absence of any human APP or PS1/2 mutation. Using the clinical diagnosis criteria, we show that this mouse model exhibits tempo-spatial features in AD patient brains, including progressive cognitive decline associated with brain atrophy, which is accompanied with extensive neuronal degeneration. Remarkably, the mice display gradual Aβ aggregation and neurofibrillary tangles formation in the brain validated by Aβ PET and Tau PET. Moreover, the mice reveal widespread neuroinflammation as shown in AD brains. Hence, Thy1-ApoE4/C/EBPβ mouse model acts as a sporadic AD mouse model, reconstituting the major AD pathologies.

Comparative gene regulatory networks modulating APOE expression in microglia and astrocytes

Background

Single-cell technologies have unveiled various transcriptional states in different brain cell types. Transcription factors (TFs) regulate the expression of related gene sets, thereby controlling these diverse expression states. Apolipoprotein E (APOE), a pivotal risk-modifying gene in Alzheimer's disease (AD), is expressed in specific glial transcriptional states associated with AD. However, it is still unknown whether the upstream regulatory programs that modulate its expression are shared across brain cell types or specific to microglia and astrocytes.

Methods

We used pySCENIC to construct state-specific gene regulatory networks (GRNs) for resting and activated cell states within microglia and astrocytes based on single-nucleus RNA sequencing data from AD patients' cortices from the Knight ADRC-DIAN cohort. We then identified replicating TF using data from the ROSMAP cohort. We identified sets of genes co-regulated with APOE by clustering the GRN target genes and identifying genes differentially expressed after the virtual knockout of TFs regulating APOE. We performed enrichment analyses on these gene sets and evaluated their overlap with genes found in AD GWAS loci.

Results

We identified an average of 96 replicating regulators for each microglial and astrocyte cell state. Our analysis identified the CEBP, JUN, FOS, and FOXO TF families as key regulators of microglial APOE expression. The steroid/thyroid hormone receptor families, including the THR TF family, consistently regulated APOE across astrocyte states, while CEBP and JUN TF families were also involved in resting astrocytes. AD GWAS-associated genes (PGRN, FCGR3A, CTSH, ABCA1, MARCKS, CTSB, SQSTM1, TSC22D4, FCER1G, and HLA genes) are co-regulated with APOE. We also uncovered that APOE-regulating TFs were linked to circadian rhythm (BHLHE40, DBP, XBP1, CREM, SREBF1, FOXO3, and NR2F1).

Conclusions

Our findings reveal a novel perspective on the transcriptional regulation of APOE in the human brain. We found a comprehensive and cell-type-specific regulatory landscape for APOE, revealing distinct and shared regulatory mechanisms across microglia and astrocytes, underscoring the complexity of APOE regulation. APOE-co-regulated genes might also affect AD risk. Furthermore, our study uncovers a potential link between circadian rhythm disruption and APOE regulation, shedding new light on the pathogenesis of AD.

C/EBPβ: A transcription factor associated with the irreversible progression of Alzheimer's disease

BACKGROUND

Alzheimer's disease (AD) is a neurodegenerative disorder distinguished by a swift cognitive deterioration accompanied by distinctive pathological hallmarks such as extracellular Aβ (β-amyloid) peptides, neuronal neurofibrillary tangles (NFTs), sustained neuroinflammation, and synaptic degeneration. The elevated frequency of AD cases and its proclivity to manifest at a younger age present a pressing challenge in the quest for novel therapeutic interventions. Numerous investigations have substantiated the involvement of C/EBPβ in the progression of AD pathology, thus indicating its potential as a therapeutic target for AD treatment.

AIMS

Several studies have demonstrated an elevation in the expression level of C/EBPβ among individuals afflicted with AD. Consequently, this review predominantly delves into the association between C/EBPβ expression and the pathological progression of Alzheimer's disease, elucidating its underlying molecular mechanism, and pointing out the possibility that C/EBPβ can be a new therapeutic target for AD.

METHODS

A systematic literature search was performed across multiple databases, including PubMed, Google Scholar, and so on, utilizing predetermined keywords and MeSH terms, without temporal constraints. The inclusion criteria encompassed diverse study designs, such as experimental, case-control, and cohort studies, restricted to publications in the English language, while conference abstracts and unpublished sources were excluded.

RESULTS

Overexpression of C/EBPβ exacerbates the pathological features of AD, primarily by promoting neuroinflammation and mediating the transcriptional regulation of key molecular pathways, including δ-secretase, apolipoprotein E4 (APOE4), acidic leucine-rich nuclear phosphoprotein-32A (ANP32A), transient receptor potential channel 1 (TRPC1), and Forkhead BoxO (FOXO).

DISCUSSION

The correlation between overexpression of C/EBPβ and the pathological development of AD, along with its molecular mechanisms, is evident. Investigating the pathways through which C/EBPβ regulates the development of AD reveals numerous multiple vicious cycle pathways exacerbating the pathological progression of the disease. Furthermore, the exacerbation of pathological progression due to C/EBPβ overexpression and its molecular mechanism is not limited to AD but also extends to other neurodegenerative diseases such as amyotrophic lateral sclerosis (ALS), Parkinson's disease (PD), and multiple sclerosis (MS).

CONCLUSION

The overexpression of C/EBPβ accelerates the irreversible progression of AD pathophysiology. Additionally, C/EBPβ plays a crucial role in mediating multiple pathways linked to AD pathology, some of which engender vicious cycles, leading to the establishment of feedback mechanisms. To sum up, targeting C/EBPβ could hold promise as a therapeutic strategy not only for AD but also for other degenerative diseases.

Cell type-specific roles of APOE4 in Alzheimer disease

The ɛ4 allele of the apolipoprotein E gene (APOE), which translates to the APOE4 isoform, is the strongest genetic risk factor for late-onset Alzheimer disease (AD). Within the CNS, APOE is produced by a variety of cell types under different conditions, posing a challenge for studying its roles in AD pathogenesis. However, through powerful advances in research tools and the use of novel cell culture and animal models, researchers have recently begun to study the roles of APOE4 in AD in a cell type-specific manner and at a deeper and more mechanistic level than ever before. In particular, cutting-edge omics studies have enabled APOE4 to be studied at the single-cell level and have allowed the identification of critical APOE4 effects in AD-vulnerable cellular subtypes. Through these studies, it has become evident that APOE4 produced in various types of CNS cell - including astrocytes, neurons, microglia, oligodendrocytes and vascular cells - has diverse roles in AD pathogenesis. Here, we review these scientific advances and propose a cell type-specific APOE4 cascade model of AD. In this model, neuronal APOE4 emerges as a crucial pathological initiator and driver of AD pathogenesis, instigating glial responses and, ultimately, neurodegeneration. In addition, we provide perspectives on future directions for APOE4 research and related therapeutic developments in the context of AD.

Inhibition of asparagine endopeptidase (AEP) effectively treats sporadic Alzheimer's disease in mice

Alzheimer's disease (AD) is a progressive neurodegenerative disease with cognitive dysfunction as its major clinical symptom. However, there is no disease-modifying small molecular medicine to effectively slow down progression of the disease. Here, we show an optimized asparagine endopeptidase (AEP, also known as δ-secretase) inhibitor, #11 A, that displays an orderly in vivo pharmacokinetics/pharmacodynamics (PK/PD) relationship and robustly attenuates AD pathologies in a sporadic AD mouse model. #11 A is brain permeable with great oral bioavailability. It blocks AEP cleavage of APP and Tau dose-dependently, and significantly decreases Aβ40 and Aβ42 and p-Tau levels in APP/PS1 and Tau P301S mice after oral administration. Notably, #11 A strongly inhibits AEP and prevents mouse APP and Tau fragmentation by AEP, leading to reduction of mouse Aβ42 (mAβ42), mAβ40 and mouse p-Tau181 levels in Thy1-ApoE4/C/EBPβ transgenic mice in a dose-dependent manner. Repeated oral administration of #11 A substantially decreases mAβ aggregation as validated by Aβ PET assay, Tau pathology, neurodegeneration and brain volume reduction, resulting in alleviation of cognitive impairment. Therefore, our results support that #11 A is a disease-modifying preclinical candidate for pharmacologically treating AD.

Single nuclei transcriptomics in human and non-human primate striatum in opioid use disorder

In brain, the striatum is a heterogenous region involved in reward and goal-directed behaviors. Striatal dysfunction is linked to psychiatric disorders, including opioid use disorder (OUD). Striatal subregions are divided based on neuroanatomy, each with unique roles in OUD. In OUD, the dorsal striatum is involved in altered reward processing, formation of habits, and development of negative affect during withdrawal. Using single nuclei RNA-sequencing, we identified both canonical (e.g., dopamine receptor subtype) and less abundant cell populations (e.g., interneurons) in human dorsal striatum. Pathways related to neurodegeneration, interferon response, and DNA damage were significantly enriched in striatal neurons of individuals with OUD. DNA damage markers were also elevated in striatal neurons of opioid-exposed rhesus macaques. Sex-specific molecular differences in glial cell subtypes associated with chronic stress were found in OUD, particularly female individuals. Together, we describe different cell types in human dorsal striatum and identify cell type-specific alterations in OUD.

Mapping enhancer and chromatin accessibility landscapes charts the regulatory network of Alzheimer's disease

BACKGROUND

Enhancers are regulatory elements that target and modulate gene expression and play a role in human health and disease. However, the roles of enhancer regulatory circuit abnormalities driven by epigenetic alterations in Alzheimer's disease (AD) are unclear.

METHODS

In this study, a multiomic integrative analysis was performed to map enhancer and chromatin accessibility landscapes and identify regulatory network abnormalities in AD. We identified differentially methylated enhancers and constructed regulatory networks across brain regions using AD brain tissue samples. Through the integration of snATAC-seq and snRNA-seq datasets, we mapped enhancers with DNA methylation alterations (DMA) and chromatin accessibility landscapes. Core regulatory triplets that contributed to AD neuropathology in specific cell types were further prioritized.

RESULTS

We revealed widespread DNA methylation alterations (DMA) in the enhancers of AD patients across different brain regions. In addition, the genome-wide transcription factor (TF) binding profiles showed that enhancers with DMA are pervasively regulated by TFs. The TF-enhancer-gene regulatory network analysis identified core regulatory triplets that are associated with brain and immune cell proportions and play important roles in AD pathogenesis. Enhancer regulatory circuits with DMA exhibited distinct chromatin accessibility patterns, which were further characterized at single-cell resolutions.

CONCLUSIONS

Our study comprehensively investigated DNA methylation-mediated regulatory circuit abnormalities and provided novel insights into the potential pathogenesis of AD.

FSH and ApoE4 contribute to Alzheimer's disease-like pathogenesis via C/EBPβ/δ-secretase in female mice

Alzheimer's disease (AD) is the most common dementia. It is known that women with one ApoE4 allele display greater risk and earlier onset of AD compared with men. In mice, we previously showed that follicle-stimulating hormone (FSH), a gonadotropin that rises in post-menopausal females, activates its receptor FSHR in the hippocampus, to drive AD-like pathology and cognitive impairment. Here we show in mice that ApoE4 and FSH jointly trigger AD-like pathogenesis by activating C/EBPβ/δ-secretase signaling. ApoE4 and FSH additively activate C/EBPβ/δ-secretase pathway that mediates APP and Tau proteolytic fragmentation, stimulating Aβ and neurofibrillary tangles. Ovariectomy-provoked AD-like pathologies and cognitive defects in female ApoE4-TR mice are ameliorated by anti-FSH antibody treatment. FSH administration facilitates AD-like pathologies in both young male and female ApoE4-TR mice. Furthermore, FSH stimulates AD-like pathologies and cognitive defects in ApoE4-TR mice, but not ApoE3-TR mice. Our findings suggest that in mice, augmented FSH in females with ApoE4 but not ApoE3 genotype increases vulnerability to AD-like process by activating C/EBPβ/δ-secretase signalling.

Bacteroides Fragilis in the gut microbiomes of Alzheimer's disease activates microglia and triggers pathogenesis in neuronal C/EBPβ transgenic mice

Gut dysbiosis contributes to Alzheimer's disease (AD) pathogenesis, and Bacteroides strains are selectively elevated in AD gut microbiota. However, it remains unknown which Bacteroides species and how their metabolites trigger AD pathologies. Here we show that Bacteroides fragilis and their metabolites 12-hydroxy-heptadecatrienoic acid (12-HHTrE) and Prostaglandin E2 (PGE2) activate microglia and induce AD pathogenesis in neuronal C/EBPβ transgenic mice. Recolonization of antibiotics cocktail-pretreated Thy1-C/EBPβ transgenic mice with AD patient fecal samples elicits AD pathologies, associated with C/EBPβ/Asparaginyl endopeptidase (AEP) pathway upregulation, microglia activation, and cognitive disorders compared to mice receiving healthy donors' fecal microbiota transplantation (FMT). Microbial 16S rRNA sequencing analysis shows higher abundance of proinflammatory Bacteroides fragilis in AD-FMT mice. Active components characterization from the sera and brains of the transplanted mice revealed that both 12-HHTrE and PGE2 activate primary microglia, fitting with poly-unsaturated fatty acid (PUFA) metabolites enrichment identified by metabolomics. Strikingly, recolonization with live but not dead Bacteroides fragilis elicited AD pathologies in Thy1-C/EBPβ transgenic mice, so did 12-HHTrE or PGE2 treatment alone. Collectively, our findings support a causal role for Bacteroides fragilis and the PUFA metabolites in activating microglia and inducing AD pathologies in Thy1- C/EBPβ transgenic mice.

C/EBPβ/AEP Signaling Drives Alzheimer's Disease Pathogenesis

Alzheimer's disease (AD) is the most common type of dementia. Almost two-thirds of patients with AD are female. The reason for the higher susceptibility to AD onset in women is unclear. However, hormone changes during the menopausal transition are known to be associated with AD. Most recently, we reported that follicle-stimulating hormone (FSH) promotes AD pathology and enhances cognitive dysfunctions via activating the CCAAT-enhancer-binding protein (C/EBPβ)/asparagine endopeptidase (AEP) pathway. This review summarizes our current understanding of the crucial role of the C/EBPβ/AEP pathway in driving AD pathogenesis by cleaving multiple critical AD players, including APP and Tau, explaining the roles and the mechanisms of FSH in increasing the susceptibility to AD in postmenopausal females. The FSH-C/EBPβ/AEP pathway may serve as a novel therapeutic target for the treatment of AD.

Neuronal ApoE4 in Alzheimer's disease and potential therapeutic targets

The most prevalent genetic risk factor for Alzheimer's disease (AD) is Apolipoprotein E (ApoE), a gene located on chromosome 19 that encodes three alleles (e2, e3, and e4) that give rise to the ApoE subtypes E2, E3, and E4, respectively. E2 and E4 have been linked to increased plasma triglyceride concentrations and are known to play a critical role in lipoprotein metabolism. The prominent pathological features of AD mainly include senile plaques formed by amyloid β (Aβ₄₂) aggregation and neuronal fibrous tangles (NFTs), and the deposited plaques are mainly composed of Aβ hyperphosphorylation and truncated head. In the central nervous system, the ApoE protein is primarily derived from astrocytes, but ApoE is also produced when neurons are stressed or affected by certain stress, injury, and aging conditions. ApoE4 in neurons induces Aβ and tau protein pathologies, leading to neuroinflammation and neuronal damage, impairing learning and memory functions. However, how neuronal ApoE4 mediates AD pathology remains unclear. Recent studies have shown that neuronal ApoE4 may lead to greater neurotoxicity, which increases the risk of AD development. This review focuses on the pathophysiology of neuronal ApoE4 and explains how neuronal ApoE4 mediates Aβ deposition, pathological mechanisms of tau protein hyperphosphorylation, and potential therapeutic targets.

A comprehensive signature based on endoplasmic reticulum stress-related genes in predicting prognosis and immunotherapy response in melanoma

Melanoma is considered as one of the most invasion types of skin cancer with high mortality rates. Although combination of immune checkpoint therapy with local surgical excision provide a novel promising therapeutic strategies, the overall prognosis of melanoma patients remains unsatisfactory. Endoplasmic reticulum (ER) stress, a process of protein misfolding and undue accumulation, has been proven to play an indispensable regulatory role in tumor progression and tumor immunity. However, whether the signature based ER genes has predictive value for the prognosis and immunotherapy of melanoma has not been systematically manifested. In this study, the LASSO regression and multivariate Cox regression were applied to construct a novel signature for predicting melanoma prognosis both in the training and testing set. Intriguingly, we found that patients endowed with high- and low-risk scores displayed differences in clinicopathologic classification, immune cell infiltration level, tumor microenvironment, and immune checkpoint treatment response. Subsequently, based on molecular biology experiments, we validated that silencing the expression of RAC1, an ERG composed of the risk signature, could restrain the proliferation and migration, promote apoptosis, as well as increase the expression of PD-1/PD-L1 and CTLA4 in melanoma cells. Taken together, the risk signature was regarded as promising predictors for melanoma prognosis and might provide prospective strategies to ameliorate patients' response to immunotherapy.

APOE expression and secretion are modulated by mitochondrial dysfunction

Mitochondria influence cellular function through both cell-autonomous and non-cell autonomous mechanisms, such as production of paracrine and endocrine factors. Here, we demonstrate that mitochondrial regulation of the secretome is more extensive than previously appreciated, as both genetic and pharmacological disruption of the electron transport chain caused upregulation of the Alzheimer's disease risk factor apolipoprotein E (APOE) and other secretome components. Indirect disruption of the electron transport chain by gene editing of SLC25A mitochondrial membrane transporters as well as direct genetic and pharmacological disruption of either complexes I, III, or the copper-containing complex IV of the electron transport chain elicited upregulation of APOE transcript, protein, and secretion, up to 49-fold. These APOE phenotypes were robustly expressed in diverse cell types and iPSC-derived human astrocytes as part of an inflammatory gene expression program. Moreover, age- and genotype-dependent decline in brain levels of respiratory complex I preceded an increase in APOE in the 5xFAD mouse model. We propose that mitochondria act as novel upstream regulators of APOE-dependent cellular processes in health and disease.

Relationship of Apolipoprotein E with Alzheimer's Disease and Other Neurological Disorders: An Updated Review

Alzheimer's disease (AD) and other neurodegenerative diseases, for which there is no effective cure, cause great social burden. Apolipoprotein E (APOE) is an important lipid transporter, which has been shown to have a close relationship with AD and other neurological disorders in an increasing number of studies, suggesting its potential as a therapeutic target. In this review, we summarize the recent advances in clinical and basic research on the role of APOE in the pathogenesis of multiple neurological diseases, with an emphasis on the new associations between APOE and AD, and between APOE and depression. The progress of APOE research in Parkinson's disease (PD) and some other neurological diseases is briefly discussed.

Mitochondria Profoundly Influence Apolipoprotein E Biology

BACKGROUND

Mitochondria can trigger Alzheimer's disease (AD)-associated molecular phenomena, but how mitochondria impact apolipoprotein E (APOE; apoE) is not well known.

OBJECTIVE

Consider whether and how mitochondrial biology influences APOE and apoE biology.

METHODS

We measured APOE expression in human SH-SY5Y neuronal cells with different forms of mitochondrial dysfunction including total, chronic mitochondrial DNA (mtDNA) depletion (ρ0 cells); acute, partial mtDNA depletion; and toxin-induced mitochondrial dysfunction. We further assessed intracellular and secreted apoE protein levels in the ρ0 cells and interrogated the impact of transcription factors and stress signaling pathways known to influence APOE expression.

RESULTS

SH-SY5Y ρ0 cells exhibited a 65-fold increase in APOE mRNA, an 8-fold increase in secreted apoE protein, and increased intracellular apoE protein. Other models of primary mitochondrial dysfunction including partial mtDNA-depletion, toxin-induced respiratory chain inhibition, and chemical-induced manipulations of the mitochondrial membrane potential similarly increased SH-SY5Y cell APOE mRNA. We explored potential mediators and found in the ρ0 cells knock-down of the C/EBPα and NFE2L2 (Nrf2) transcription factors reduced APOE mRNA. The activity of two mitogen-activated protein kinases, JNK and ERK, also strongly influenced ρ0 cell APOE mRNA levels.

CONCLUSION

Primary mitochondrial dysfunction either directly or indirectly activates APOE expression in a neuronal cell model by altering transcription factors and stress signaling pathways. These studies demonstrate mitochondrial biology can influence the biology of the APOE gene and apoE protein, which are implicated in AD.

Risperidone ameliorated 1,2-Diacetylbenzene-induced cognitive impairments in mice via activating prolactin signaling pathways

Cognitive impairment and organic solvent exposure have been becoming public health concerns due to an increasingly aging population, increased life expectancy, urbanization, and industrialization. Converging evidence indicates the link between 1,2-diacetylbenzene (DAB), prolactin (PRL), risperidone, and cognitive impairment. However, these relationships remain unclear. We investigated the therapeutic properties of risperidone in DAB-induced cognitive impairment using both in vivo and in silico methods. Risperidone alleviated DAB-induced cognitive impairment in hippocampal mice, possibly by inhibiting GSK-3β, β-amyloid, CDK5, BACE, and tau hyperphosphorylation. Risperidone also attenuated the activation of TREM-1/DAP12/NLRP3/caspase-1/IL-1β, and TLR4/NF-κB pathways caused by DAB. Furthermore, risperidone inhibited DAB-induced oxidative stress, advanced glycation end products, and proinflammatory cytokines, as well as increased the expression of Nrf2, IL-10, Stat3, MDM2, and catalase activity. On the other hand, risperidone activated the expression of IRS1, PI3K, AKT, BDNF, Drd2, Scna5, and Trt as well as reduced the Bax/Bcl2 ratio and Caspase-3 levels. In silico analyses identified the prolactin signaling pathway, miR-155-5p, miR-34a-5p, and CEBPB as the main molecular mechanisms involved in the pathophysiology of DAB-induced cognitive impairment and targeted by risperidone. Our results suggest that risperidone could be used to treat cognitive impairment caused by organic solvents, especially DAB.

Aging-associated REGγ proteasome decline predisposes to tauopathy

The REGγ-20S proteasome is an ubiquitin- and ATP-independent degradation system, targeting selective substrates, possibly helping to regulate aging. The studies we report here demonstrate that aging-associated REGγ decline predisposes to decreasing tau turnover, as in a tauopathy. The REGγ proteasome promotes degradation of human and mouse tau, notably phosphorylated tau and toxic tau oligomers that shuttle between the cytoplasm and nuclei. REGγ-mediated proteasomal degradation of tau was validated in 3- to 12-month-old REGγ KO mice, REGγ KO;PS19 mice, and PS19 mice with forebrain conditional neuron-specific overexpression of REGγ (REGγ OE) and behavioral abnormalities. Coupled with tau accumulation, we found with REGγ-deficiency, neuron loss, dendrite reduction, tau filament accumulation, and microglial activation are much more prominent in the REGγ KO;PS19 than the PS19 model. Moreover, we observed that the degenerative neuronal lesions and aberrant behaviors were alleviated in REGγ OE;PS19 mice. Memory and other behavior analysis substantiate the role of REGγ in prevention of tauopathy-like symptoms. In addition, we investigated the potential mechanism underlying aging-related REGγ decline. This study provides valuable insights into the novel regulatory mechanisms and potential therapeutic targets for tau-related neurodegenerative diseases.

Somatic Mutations and Alzheimer’s Disease

Alzheimer’s disease (AD) represents a global health challenge, with an estimated 55 million people suffering from the non-curable disease across the world. While amyloid-β plaques and tau neurofibrillary tangles in the brain define AD proteinopathy, it has become evident that diverse coding and non-coding regions of the genome may significantly contribute to AD neurodegeneration. The diversity of factors associated with AD pathogenesis, coupled with age-associated damage, suggests that a series of triggering events may be required to initiate AD. Since somatic mutations accumulate with aging, and aging is a major risk factor for AD, there is a great potential for somatic mutational events to drive disease. Indeed, recent data from the Gozes team/laboratories as well as other leading laboratories correlated the accumulation of somatic brain mutations with the progression of tauopathy. In this review, we lay the current perspectives on the principal genetic factors associated with AD and the potential causes, highlighting the contribution of somatic mutations to the pathogenesis of late onset Alzheimer’s disease. The roles that artificial intelligence and big data can play in accelerating the progress of causal somatic mutation markers/biomarkers identification, and the associated drug discovery/repurposing, have been highlighted for future AD and other neurodegenerative studies, with the aim to bring hope for the vulnerable aging population.

C/EBPβ/AEP signaling couples atherosclerosis to the pathogenesis of Alzheimer's disease

Atherosclerosis (ATH) and Alzheimer's disease (AD) are both age-dependent inflammatory diseases, associated with infiltrated macrophages and vascular pathology and overlapping molecules. C/EBPβ, an Aβ or inflammatory cytokine-activated transcription factor, and AEP (asparagine endopeptidase) are intimately implicated in both ATH and AD; however, whether C/EBPβ/AEP signaling couples ATH to AD pathogenesis remains incompletely understood. Here we show that C/EBPβ/AEP pathway mediates ATH pathology and couples ATH to AD. Deletion of C/EBPβ or AEP from primary macrophages diminishes cholesterol load, and inactivation of this pathway reduces foam cell formation and lesions in aorta in ApoE-/- mice, fed with HFD (high-fat-diet). Knockout of ApoE from 3xTg AD mouse model augments serum LDL and increases lesion areas in the aorta. Depletion of C/EBPβ or AEP from 3xTg/ApoE-/- mice substantially attenuates these effects and elevates cerebral blood flow and vessel length, improving cognitive functions. Strikingly, knockdown of ApoE from the hippocampus of 3xTg mice decreases the cerebral blood flow and vessel length and aggravates AD pathologies, leading to cognitive deficits. Inactivation of C/EBPβ/AEP pathway alleviates these events and restores cognitive functions. Hence, our findings demonstrate that C/EBPβ/AEP signaling couples ATH to AD via mediating vascular pathology.

Mining comorbidities of opioid use disorder from FDA adverse event reporting system and patient electronic health records

BACKGROUND

Opioid use disorder (OUD) has become an urgent health problem. People with OUD often experience comorbid medical conditions. Systematical approaches to identifying co-occurring conditions of OUD can facilitate a deeper understanding of OUD mechanisms and drug discovery. This study presents an integrated approach combining data mining, network construction and ranking, and hypothesis-driven case-control studies using patient electronic health records (EHRs).

METHODS

First, we mined comorbidities from the US Food and Drug Administration Adverse Event Reporting System (FAERS) of 12 million unique case reports using frequent pattern-growth algorithm. The performance of OUD comorbidity mining was measured by precision and recall using manually curated known OUD comorbidities. We then constructed a disease comorbidity network using mined association rules and further prioritized OUD comorbidities. Last, novel OUD comorbidities were independently tested using EHRs of 75 million unique patients.

RESULTS

The OUD comorbidities from association rules mining achieves a precision of 38.7% and a recall of 78.2 Based on the mined rules, the global DCN was constructed with 1916 nodes and 32,175 edges. The network-based OUD ranking result shows that 43 of 55 known OUD comorbidities were in the first decile with a precision of 78.2%. Hypothyroidism and type 2 diabetes were two top-ranked novel OUD comorbidities identified by data mining and network ranking algorithms. Based on EHR-based case-control studies, we showed that patients with OUD had significantly increased risk for hyperthyroidism (AOR = 1.46, 95% CI 1.43-1.49, p value < 0.001), hypothyroidism (AOR = 1.45, 95% CI 1.42-1.48, p value < 0.001), type 2-diabetes (AOR = 1.28, 95% CI 1.26-1.29, p value < 0.001), compared with individuals without OUD.

CONCLUSION

Our study developed an integrated approach for identifying and validating novel OUD comorbidities from health records of 87 million unique patients (12 million for discovery and 75 million for validation), which can offer new opportunities for OUD mechanism understanding, drug discovery, and multi-component service delivery for co-occurring medical conditions among patients with OUD.

Neuroprotective Mechanisms of Ginsenoside Rb1 in Central Nervous System Diseases

Panax ginseng and Panax notoginseng, two well-known herbs with enormous medical value in Asian countries, have a long usage history in China for the therapy of some diseases, such as stroke. Ginsenoside Rb1 is one of most important active ingredients in Panax ginseng and Panax notoginseng. In the last two decades, more attention has focused on ginsenoside Rb1 as an antioxidative, anti-apoptotic and anti-inflammatory agent that can protect the nervous system. In the review, we summarize the neuroprotective roles of ginsenoside Rb1 and its potential mechanisms in central nervous system diseases (CNSDs), including neurodegenerative diseases, cerebral ischemia injury, depression and spinal cord injury. In conclusion, ginsenoside Rb1 has a potential neuroprotection due to its inhibition of oxidative stress, apoptosis, neuroinflammation and autophagy in CNSDs and may be a promising candidate agent for clinical therapy of CNSDs in the future.

Neuroprotective Mechanisms of Ginsenoside Rb1 in Central Nervous System Diseases

Panax ginseng and Panax notoginseng, two well-known herbs with enormous medical value in Asian countries, have a long usage history in China for the therapy of some diseases, such as stroke. Ginsenoside Rb1 is one of most important active ingredients in Panax ginseng and Panax notoginseng. In the last two decades, more attention has focused on ginsenoside Rb1 as an antioxidative, anti-apoptotic and anti-inflammatory agent that can protect the nervous system. In the review, we summarize the neuroprotective roles of ginsenoside Rb1 and its potential mechanisms in central nervous system diseases (CNSDs), including neurodegenerative diseases, cerebral ischemia injury, depression and spinal cord injury. In conclusion, ginsenoside Rb1 has a potential neuroprotection due to its inhibition of oxidative stress, apoptosis, neuroinflammation and autophagy in CNSDs and may be a promising candidate agent for clinical therapy of CNSDs in the future.

Thioredoxin-1 inhibits amyloid-β25-35-induced activation of NLRP1/caspase-1/GSDMD pyroptotic pathway in PC12 cells

BACKGROUND

Alzheimer's disease (AD), the most common neurodegenerative disease, is charactered by these accepted pathological features, such as β-amyloid (Aβ) plaques outside the neurons and neurofibrillary tangles inside the neurons. In recent years, several studies have demonstrated that pyroptosis is associated with the development of AD process. However, whether Aβ25-35 induces pyroptosis is still unclear. Thioredoxin-1 (Trx-1), an intracellular multifunctional protein, showed neuroprotective roles by inhibiting the neurotoxicity of Aβ, attenuating the apoptosis of brain neurons and improving the spatial learning and memory ability in AD models. Whether Trx-1 could inhibit pyroptosis in AD needs to be further investigated.

METHODS AND RESULTS

In the present study, MTT assay was employed to detected the viability. Western blotting was employed to detect the protein levels. Enzyme linked immunosorbent assay was used to examine the intracellular and extracellular levels of IL-18 and IL-1β. Chronic Aβ25-35 treatment remarkedly compromised the viability of PC12 cells, increased the expression of NOD-like receptor pyrin domain containing 1 (NLRP-1), caspase-1 and gasdermin D (GSDMD), and promoted the extracellular release of interleukin (IL)-18 and IL-1β. Simultaneously, Aβ25-35 treatment also significantly reduced the intracellular protein levels of Trx-1. Pharmacological inhibition of Trx-1 activity further decreased the cell viability, activated the NLRP-1/caspase-1/GSDMD pyroptotic pathway, and exacerbated the extracellular release of IL-18 and IL-1β.

CONCLUSIONS

These data suggest that Trx-1 may play a potential inhibitory effect on Aβ25-35-induced pyroptosis.

Inhibition of the CEBPβ-NFκB interaction by nanocarrier-packaged Carnosic acid ameliorates glia-mediated neuroinflammation and improves cognitive function in an Alzheimer's disease model

Neuroinflammation occurs early in Alzheimer’s disease (AD). The initial stage of AD is related to glial dysfunction, which contributes to impairment of Aβ clearance and disruption of synaptic connection. CEBPβ, a member of the CCAAT-enhancer-binding protein (CEBP) family, modulates the expression of inflammation-associated genes, and its expression is elevated in brains undergoing degeneration and injured brains. However, the mechanism underlying CEBPβ-mediated chronic inflammation in AD is unclear. In this study, we observed that increases in the levels of nuclear CEBPβ facilitated the interaction of CEBPβ with the NFκB p65 subunit, increasing the transcription of proinflammatory cytokines in the APP/PS1 mouse brain. Oral administration of nanocarrier-packaged carnosic acid (CA) reduced the aberrant activation of microglia and astrocytes and diminished mature IL-1β, TNFα and IL-6 production in the APP/PS1 mouse brain. CA administration reduced β-amyloid (Aβ) deposition and ameliorated cognitive impairment in APP/PS1 mice. We observed that CA blocked the interaction of CEBPβ with NFκB p65, and chromatin immunoprecipitation revealed that CA reduced the transcription of the NFκB target genes TNFα and IL-6. We confirmed that CA alleviated inflammatory mediator-induced neuronal degeneration and reduced Aβ secretion by inhibiting the CEBPβ-NFκB signalling pathway in vitro. Sulfobutyl ether-beta-cyclodextrin (SBEβCD) was used as the encapsulation agent for the CA-loaded nanocarrier to overcome the poor water solubility and enhance the brain bioavailability of CA. The CA nanoparticles (NPs) had no obvious toxicity. We demonstrated a feasible SBEβCD-based nanodelivery system targeting the brain. Our data provide experimental evidence that CA-loaded NPs are potential therapeutic agents for AD treatment.

Dopaminergic Neurons in the Ventral Tegmental-Prelimbic Pathway Promote the Emergence of Rats from Sevoflurane Anesthesia

Dopaminergic neurons in the ventral tegmental area (VTA) play an important role in cognition, emergence from anesthesia, reward, and aversion, and their projection to the cortex is a crucial part of the "bottom-up" ascending activating system. The prelimbic cortex (PrL) is one of the important projection regions of the VTA. However, the roles of dopaminergic neurons in the VTA and the VTADA-PrL pathway under sevoflurane anesthesia in rats remain unclear. In this study, we found that intraperitoneal injection and local microinjection of a dopamine D1 receptor agonist (Chloro-APB) into the PrL had an emergence-promoting effect on sevoflurane anesthesia in rats, while injection of a dopamine D1 receptor antagonist (SCH23390) deepened anesthesia. The results of chemogenetics combined with microinjection and optogenetics showed that activating the VTADA-PrL pathway prolonged the induction time and shortened the emergence time of anesthesia. These results demonstrate that the dopaminergic system in the VTA has an emergence-promoting effect and that the bottom-up VTADA-PrL pathway facilitates emergence from sevoflurane anesthesia.

Adult-onset CNS myelin sulfatide deficiency is sufficient to cause Alzheimer's disease-like neuroinflammation and cognitive impairment

BACKGROUND

Human genetic association studies point to immune response and lipid metabolism, in addition to amyloid-beta (Aβ) and tau, as major pathways in Alzheimer's disease (AD) etiology. Accumulating evidence suggests that chronic neuroinflammation, mainly mediated by microglia and astrocytes, plays a causative role in neurodegeneration in AD. Our group and others have reported early and dramatic losses of brain sulfatide in AD cases and animal models that are mediated by ApoE in an isoform-dependent manner and accelerated by Aβ accumulation. To date, it remains unclear if changes in specific brain lipids are sufficient to drive AD-related pathology.

METHODS

To study the consequences of CNS sulfatide deficiency and gain insights into the underlying mechanisms, we developed a novel mouse model of adult-onset myelin sulfatide deficiency, i.e., tamoxifen-inducible myelinating glia-specific cerebroside sulfotransferase (CST) conditional knockout mice (CSTfl/fl/Plp1-CreERT), took advantage of constitutive CST knockout mice (CST-/-), and generated CST/ApoE double knockout mice (CST-/-/ApoE-/-), and assessed these mice using a broad range of methodologies including lipidomics, RNA profiling, behavioral testing, PLX3397-mediated microglia depletion, mass spectrometry (MS) imaging, immunofluorescence, electron microscopy, and Western blot.

RESULTS

We found that mild central nervous system (CNS) sulfatide losses within myelinating cells are sufficient to activate disease-associated microglia and astrocytes, and to increase the expression of AD risk genes (e.g., Apoe, Trem2, Cd33, and Mmp12), as well as previously established causal regulators of the immune/microglia network in late-onset AD (e.g., Tyrobp, Dock, and Fcerg1), leading to chronic AD-like neuroinflammation and mild cognitive impairment. Notably, neuroinflammation and mild cognitive impairment showed gender differences, being more pronounced in females than males. Subsequent mechanistic studies demonstrated that although CNS sulfatide losses led to ApoE upregulation, genetically-induced myelin sulfatide deficiency led to neuroinflammation independently of ApoE. These results, together with our previous studies (sulfatide deficiency in the context of AD is mediated by ApoE and accelerated by Aβ accumulation) placed both Aβ and ApoE upstream of sulfatide deficiency-induced neuroinflammation, and suggested a positive feedback loop where sulfatide losses may be amplified by increased ApoE expression. We also demonstrated that CNS sulfatide deficiency-induced astrogliosis and ApoE upregulation are not secondary to microgliosis, and that astrogliosis and microgliosis seem to be driven by activation of STAT3 and PU.1/Spi1 transcription factors, respectively.

CONCLUSION

Our results strongly suggest that sulfatide deficiency is an important contributor and driver of neuroinflammation and mild cognitive impairment in AD pathology.

Modifiable factors associated with mental health symptoms in siblings of adolescents with anorexia nervosa

PURPOSE

Research demonstrates that anorexia nervosa (AN) takes a significant toll on affected families, yet the well-being of siblings has been largely overlooked. This study examines mental health symptoms in siblings of adolescents with AN and seeks to identify modifiable factors associated with well-being.

METHOD

Participants included 34 siblings (aged 11-19) of adolescents with AN and 47 age and sex matched controls. Participants and their caregivers completed assessments of anxiety, depression, internalizing and externalizing problems, and parentification. Siblings of adolescents with AN also completed the Sibling Perception Questionnaire, an assessment of perceptions and attitudes about AN.

RESULTS

Analyses indicated that siblings of adolescents with AN reported greater anxiety and parentification than controls. On caregiver reports of participants' internalizing and externalizing symptoms, no significant differences were found across groups. In siblings of adolescents with AN, females were more vulnerable to anxiety, depression, and negative attitudes and perceptions about AN than males. Perceived negative interpersonal interactions, specific to having a brother or sister with AN, were associated with greater anxiety and depression among AN siblings.

CONCLUSION

Findings from this pilot study suggest that siblings of adolescents with AN are vulnerable to anxiety and parentification behaviors. Negative interpersonal interactions specific to having a brother or sister with AN may perpetuate risk for poorer well-being. Caregivers may not be attuned to these struggles, highlighting the importance of provider and family education about sibling vulnerabilities. Therapeutic interventions that target siblings of adolescents with AN are also indicated.

LEVEL OF EVIDENCE

Level III, case-control analytic study.

Neurotrophins as Key Regulators of Cell Metabolism: Implications for Cholesterol Homeostasis

Neurotrophins constitute a family of growth factors initially characterized as predominant mediators of nervous system development, neuronal survival, regeneration and plasticity. Their biological activity is promoted by the binding of two different types of receptors, leading to the generation of multiple and variegated signaling cascades in the target cells. Increasing evidence indicates that neurotrophins are also emerging as crucial regulators of metabolic processes in both neuronal and non-neuronal cells. In this context, it has been reported that neurotrophins affect redox balance, autophagy, glucose homeostasis and energy expenditure. Additionally, the trophic support provided by these secreted factors may involve the regulation of cholesterol metabolism. In this review, we examine the neurotrophins' signaling pathways and their effects on metabolism by critically discussing the most up-to-date information. In particular, we gather experimental evidence demonstrating the impact of these growth factors on cholesterol metabolism.

Observational Study of Chlorpromazine in Hospitalized Patients with COVID-19

Introduction

Chlorpromazine has been suggested as being potentially useful in patients with coronavirus disease 2019 (COVID-19) on the grounds of its potential antiviral and anti-inflammatory effects.

Objective

The aim of this study was to examine the association between chlorpromazine use and mortality among adult patients hospitalized for COVID-19.

Methods

We conducted an observational, multicenter, retrospective study at Assistance Publique-Hôpitaux de Paris (AP-HP) Greater Paris University hospitals. Study baseline was defined as the date of first prescription of chlorpromazine during hospitalization for COVID-19. The primary endpoint was death. Among patients who had not been hospitalized in intensive care units (ICUs), we compared this endpoint between those who received chlorpromazine and those who did not, in time-to-event analyses adjusted for patient characteristics, clinical markers of disease severity, and other psychotropic medications. The primary analysis used a Cox regression model with inverse probability weighting. Multiple sensitivity analyses were performed.

Results

Of the 14,340 adult inpatients hospitalized outside ICUs for COVID-19, 55 patients (0.4%) received chlorpromazine. Over a mean follow-up of 14.3 days (standard deviation [SD] 18.2), death occurred in 13 patients (23.6%) who received chlorpromazine and 1289 patients (9.0%) who did not. In the primary analysis, there was no significant association between chlorpromazine use and mortality (hazard ratio [HR] 2.01, 95% confidence interval [CI] 0.75–5.40; p = 0.163). Sensitivity analyses included a Cox regression in a 1:5 ratio matched analytic sample that showed a similar result (HR 1.67, 95% CI 0.91–3.06; p = 0.100) and a multivariable Cox regression that indicated a significant positive association (HR 3.10, 95% CI 1.31–7.34; p = 0.010).

Conclusion

Our results suggest that chlorpromazine prescribed at a mean daily dose of 70.8 mg (SD 65.3) was not associated with reduced mortality.

Supplementary Information

The online version contains supplementary material available at 10.1007/s40261-021-01001-0.