Oleoylethanolamide facilitates PPARα and TFEB signaling and attenuates Aβ pathology in a mouse model of Alzheimer's disease

The compound (E)-2-(3,4-dihydroxystyryl)-3-hydroxy-4H-pyran-4-one alleviates neuroinflammation and cognitive impairment in a mouse model of Alzheimer's disease

JOURNAL/nrgr/04.03/01300535-202511000-00034/figure1/v/2024-12-20T164640Z/r/image-tiff Previous studies have shown that the compound (E)-2-(3,4-dihydroxystyryl)-3-hydroxy-4H-pyran-4-one (D30), a pyromeconic acid derivative, possesses antioxidant and anti-inflammatory properties, inhibits amyloid-β aggregation, and alleviates scopolamine-induced cognitive impairment, similar to the phase III clinical drug resveratrol. In this study, we established a mouse model of Alzheimer's disease via intracerebroventricular injection of fibrillar amyloid-β to investigate the effect of D30 on fibrillar amyloid-β-induced neuropathology. Our results showed that D30 alleviated fibrillar amyloid-β-induced cognitive impairment, promoted fibrillar amyloid-β clearance from the hippocampus and cortex, suppressed oxidative stress, and inhibited activation of microglia and astrocytes. D30 also reversed the fibrillar amyloid-β-induced loss of dendritic spines and synaptic protein expression. Notably, we demonstrated that exogenous fibrillar amyloid-β introduced by intracerebroventricular injection greatly increased galectin-3 expression levels in the brain, and this increase was blocked by D30. Considering the role of D30 in clearing amyloid-β, inhibiting neuroinflammation, protecting synapses, and improving cognition, this study highlights the potential of galectin-3 as a promising treatment target for patients with Alzheimer's disease.

Dicyclohexyl phthalate derails trophoblast function and lipid metabolism through NDRG1 by targeting PPARα:RXRα

Phthalates (PAEs) can impair trophoblast cell and subsequent placental development, adversely affecting pregnancy. The effects of dicyclohexyl phthalate (DCHP), the main PAE homologue in urban household dust, on trophoblast function and placental development are unknown. In this study, we investigated the effects and potential mechanisms of DCHP on trophoblast function and placental development by constructing in vitro trophoblast (10, 20, 30 μM) and in vivo mouse pregnancy (25, 50, 100 mg/kg bw) exposure models. We found that exposure to DCHP during pregnancy led to the accumulation of placental lipid droplets and foetal weight gain. Consistently, DCHP induced the uptake of fatty acids by HTR-8/SVneo cells, leading to intracellular lipid droplet accumulation and mitochondrial dysfunction while inhibiting cell migration and invasion. This suggests that metabolic processes can serve as important links for environmental pollutants to interfere with bodily functions. Knocking down N-myc Downstream-Regulated Gene 1 (NDRG1) can alleviate lipid metabolism abnormalities caused by DCHP exposure while restoring cell migration and invasion abilities. Further research has found that the enhanced transcriptional activity of PPARα:RXRα is an important molecular initiating event for the role of DCHP, which promotes the transcription of downstream target gene NDRG1 by binding to PPARα:RXRα. These findings fill the research gap regarding the effects and related mechanisms of DCHP exposure on the placenta, help explore prevention and treatment strategies for DCHP reproductive toxicity, and provide new insights into toxicological research on environmental pollutants.

Molecular mechanisms of MAPK9, BAX, and TFEB proteins: Genetic correlations between oxidative stress and autophagy pathways in Alzheimer's disease

Alzheimer's disease (AD) is a complex neurodegenerative disease whose pathological mechanisms involve dysregulation of oxidative stress and autophagy pathways. MAPK9, BAX and TFEB were used as key proteins. Wayne analysis was used to identify genes associated with autophagy and oxidative stress, and protein-protein interaction (PPI) networks were constructed to study the associations between key genes. The key genes were mined by machine learning algorithm and prognostic marker models were constructed. The immune characteristics of AD were investigated by gene collection enrichment analysis (GSEA) and immunoresponse pathway enrichment analysis, and the clinical application potential was evaluated by drug prediction and molecular docking analysis. Finally, Mendelian randomization (MR) analysis was used to verify the causal relationship between key genes and AD. The results showed that we successfully identified several genes associated with Alzheimer's disease, including MAPK9, BAX, and TFEB. GSEA analysis showed their active involvement in the immune response, indicating the importance of immune function in AD. Drug prediction models reveal potential therapeutic targets for these key genes.

Ginsenoside 1 mitigates postoperative cognitive dysfunction by enhancing microglial Aβ clearance through the endo-lysosomal pathway

BACKGROUND

Postoperative cognitive dysfunction (POCD) is a common complication in patients after surgery, especially in the elderly. The incidence of POCD not only impaired learning and memory, but also increased morbidity and mortality in patients. However, the exploration of therapeutic agents is limited. Ginsenoside 1 (Rg1) is one of the main compounds of ginseng, which exhibits bioactive and neuroprotective efficiency. In the present study, we aimed to investigate the effects of Rg1 on POCD.

METHODS

The POCD model was established by performing aseptic laparotomy surgery under anesthesia in 18-month mice. The cognition and anxiety of mice were assessed with MWM, OFT, and NOR tests. An in vitro model was performed on BV2 microglial cells. RNA sequencing, Western blotting, electrophysiology, Golgi staining, engulfment, and immunofluorescence analysis were performed.

RESULTS

Our results showed that Rg1 effectively alleviated the cognitive dysfuncion and anxiety of POCD mice. Transcriptomic sequencing data in microglia indicated that Rg1 mainly affects endosomes and lysosomes. By upregulating Rab7 and TFEB expression, Rg1 promoted microglial engulfment of Aβ through the endo-lysosomal pathway. Additionally, Rg1 reduced inflammatory levels, increased synaptic plasticity, and mitigated neuronal damage caused by Aβ. Moreover, the effects of Rg1 on TFEB depended on MEK/ERK signaling, while activation of MEK reversed Rg1's protective effects.

CONCLUSIONS

In conclusion, our study demonstrates that Rg1 can effectively ameliorate cognitive and synaptic deficit by enhancing microglial Aβ clearance through the endo-lysosomal pathway in aged POCD mice, which provides a potential strategy for the prevention of POCD.

Regulatory Mechanisms and Therapeutic Implications of Lysosomal Dysfunction in Alzheimer's Disease

Alzheimer's disease (AD) is characterized by the accumulation of amyloid-beta (Aβ) plaques, neurofibrillary tangles (NFTs) formed from hyperphosphorylated Tau, and widespread neuronal loss. The autophagy-lysosomal pathway plays a crucial role in maintaining cellular homeostasis by degrading and recycling of damaged organelles and aggregate amyloid proteins implicated in AD. Lysosomes are key effectors of autophagic process, responsible for the breakdown of a variety of damaged organelles and aggregate or dysfunctional proteins. This review examines the role of lysosomal dysfunction in AD pathophysiology, focusing on genetic factors, acidification abnormalities, and other contributing factors. We also explore the involvement of lysosomal dysfunction of microglia in AD pathology, and cover the role of lysosomal stress response (LSR) in cellular response to neuronal injury associated with AD. Furthermore, we discuss potential therapeutic strategies targeting lysosomal proteolysis pathway and addressing lysosomal dysfunction for AD treatment, including the pharmacologically activating lysosomal activity, regulating TFEB, and considering other emerging approaches.

Unveiling the role of astrogliosis in Alzheimer's disease Pathology: Insights into mechanisms and therapeutic approaches

Alzheimer's disease (AD) is one of the most debilitating age-related disorders that affect people globally. It impacts social and cognitive behavior of the individual and is characterized by phosphorylated tau and Aβ accumulation. Astrocytesmaintain a quiescent, anti-inflammatory state on anatomical level, expressing few cytokines and exhibit phagocytic activity to remove misfolded proteins. But in AD, in response to specific stimuli, astrocytes overstimulate their phagocytic character with overexpressing cytokine gene modules. Upon interaction with generated Aβ and neurofibrillary tangle, astrocytes that are continuously activated release a large number of inflammatory cytokines. This cytokine storm leads to neuroinflammation which is also one of the recognizable features of AD. Astrogliosis eventually promotes cholinergic dysfunction, calcium imbalance, oxidative stress and excitotoxicity. Furthermore, C5aR1, Lcn2/, BDNF/TrkB and PPARα/TFEB signaling dysregulation has a major impact on the disease progression. This review clarifies numerous ways that lead to astrogliosis, which is stimulated by a variety of processes that exacerbate AD pathology and make it a suitable target for AD treatment. Drugs under clinical and preclinical investigations that target several pathways managing astrogliosis and are efficacious in ameliorating the pathology of the disease are also included in this study. D-ALA2GIP, TRAM-34, Genistein, L-serine, MW150 and XPro1595 are examples of few drugs targeting astrogliosis. Therefore, this study may aid in the development of a potent therapeutic agent for ameliorating astrogliosis mediated AD progression.

Compound (E)-2-(3,4-dihydroxystyryl)-3-hydroxy-4H-pyran-4-one downregulation of Galectin-3 ameliorates Aβ pathogenesis-induced neuroinflammation in 5 × FAD mice

AIMS

Alzheimer's disease (AD) is characterized by β-amyloid (Aβ) aggregation and neuroinflammation, leading to progressive synaptic loss and cognitive decline. Recent evidence suggests that Galectin-3 (Gal-3) plays a critical role in Aβ pathogenesis. However, strategies to simultaneously target Gal-3 and Aβ are currently insufficient. This study evaluates the therapeutic efficacy of (E)-2-(3,4-dihydroxystyryl)-3-hydroxy-4H-pyran-4-one (D30), in reducing Gal-3 and Aβ pathogenesis.

MATERIALS AND METHODS

We applied exogenous oligomeric Aβ and used 5 × FAD mice to assess the impact of Aβ on Gal-3 deposition, microglial activation, and cognitive function. Thy1-EGFP mice were employed to observe dendritic spines. Comprehensive evaluations of D30's effects included behavioral studies, transcriptomic analysis, Western blotting, and immunofluorescent staining. The interaction between D30 and Gal-3 was examined using fluorescence resonance energy transfer (FRET) and microscale thermophoresis (MST).

KEY FINDINGS

D30 effectively reduced Aβ monomer production by inhibiting Amyloid Precursor Protein (APP) and presenilin 1 (PS1) expression, and decreased Aβ aggregation. Treatment with D30 improved cognitive functions, reversed dendritic spine loss, and increased PSD95 expression in 5 × FAD mice. Additionally, D30 significantly lowered Gal-3 levels in both plasma and hippocampal tissues. D30 binds to Gal-3 and disrupts the interaction between Gal-3 and TREM2, as confirmed by FRET and MST.

SIGNIFICANCE

Our findings underscore the interaction between Gal-3 and Aβ in AD and its role in systemic inflammation using the 5 × FAD mouse model. Being able to target and regulate Gal-3 together with Aβ is crucial for preventing neuroinflammation and protecting synapses, D30 emerged as a novel compound with promising potential for AD treatment.

Gastrodin ameliorates oxidative stress-induced RPE damage by facilitating autophagy and phagocytosis through PPARα-TFEB/CD36 signal pathway

Age-related macular degeneration (AMD), the leading cause of irreversible blindness in the elderly, is primarily characterized by the degeneration of the retinal pigment epithelium (RPE). However, effective therapeutic options for dry AMD are currently lacking, necessitating further exploration into preventive and pharmaceutical interventions. This study aimed to investigate the protective effects of gastrodin on RPE cells exposed to oxidative stress. We constructed an in vitro oxidative stress model of 4-hydroxynonenal (4-HNE) and performed RNA-seq, and demonstrated the protective effect of gastrodin through mouse experiments. Our findings reveal that gastrodin can inhibit 4-HNE-induced oxidative stress, effectively improving the mitochondrial and lysosomal dysfunction of RPE cells. We further elucidated that gastrodin promotes autophagy and phagocytosis through activating the PPARα-TFEB/CD36 signaling pathway. Interestingly, these outcomes were corroborated in a mouse model, in which gastrodin maintained retinal integrity and reduced RPE disorganization and degeneration under oxidative stress. The accumulation of LC3B and SQSTM1 in mouse RPE-choroid was also reduced. Moreover, activating PPARα and downstream pathways to restore autophagy and phagocytosis, thereby countering RPE injury from oxidative stress. In conclusion, this study demonstrated that gastrodin maintains the normal function of RPE cells by reducing oxidative stress, enhancing their phagocytic function, and restoring the level of autophagic flow. These findings suggest that gastrodin is a novel formulation with potential applications in the development of AMD disease.

Region-Specific Gene Expression Changes Associated with Oleoylethanolamide-Induced Attenuation of Alcohol Self-Administration

Oleoylethanolamide (OEA) is a lipid with anti-inflammatory activity that modulates multiple reward-related behaviors. Previous studies have shown that OEA treatment reduces alcohol self-administration (SA) while inhibiting alcohol-induced inflammatory signaling. Nevertheless, the specific mechanisms that OEA targets to achieve these effects have not been widely explored. Here, we tested the effects of OEA treatment during alcohol SA, extinction or previous to cue-induced reinstatement of alcohol seeking. In addition, we measured gene expression changes in the striatum and hippocampus of relevant receptors for alcohol consumption (Drd1, Drd2, Cnr1, Oprm) as well as immune-related proteins (Il-6, Il-1β, Tlr4) and the brain-derived neurotrophic factor (Bdnf). Our results confirmed that when administered contingently, systemic OEA administration reduced alcohol SA and attenuated cue-induced reinstatement. Interestingly, we also observed that OEA treatment reduced the number of sessions needed for the extinction of alcohol seeking. Biochemical analyses showed that OEA induced gene expression changes in dopamine and cannabinoid receptors in the striatum and hippocampus. In addition, OEA treatment modulated the long-term immune response and increased Bdnf expression. These results suggest that boosting OEA levels may be an effective strategy for reducing alcohol SA and preventing relapse.

Complement C3aR signaling: Immune and metabolic modulation and its impact on Alzheimer's disease

Alzheimer's disease (AD) is a progressive neurodegenerative disorder and the most common cause of dementia among the elderly population. Despite its widespread prevalence, our comprehension of the intricate mechanisms governing the pathogenesis of the disease remains incomplete, posing a challenge for the development of efficient therapies. Pathologically characterized by the presence of amyloid β plaques and neurofibrillary tau tangles, AD is also accompanied by the hyperactivation of glial cells and the immune system. The complement cascade, the evolutionarily conserved innate immune pathway, has emerged as a significant contributor to AD. This review focuses on one of the complement components, the C3a receptor (C3aR), covering its structure, ligand-receptor interaction, intracellular signaling and its functional consequences. Drawing insights from cellular and AD mouse model studies, we present the multifaceted role of complement C3aR signaling in AD and attempt to convey to the readers that C3aR acts as a crucial immune and metabolic modulator to influence AD pathogenesis. Building on this framework, the objective of this review is to inform future research endeavors and facilitate the development of therapeutic strategies for this challenging condition.

Targeting dysregulated lipid metabolism for the treatment of Alzheimer's disease and Parkinson's disease: Current advancements and future prospects

Alzheimer's and Parkinson's diseases are two of the most frequent neurological diseases. The clinical features of AD are memory decline and cognitive dysfunction, while PD mainly manifests as motor dysfunction such as limb tremors, muscle rigidity abnormalities, and slow gait. Abnormalities in cholesterol, sphingolipid, and glycerophospholipid metabolism have been demonstrated to directly exacerbate the progression of AD by stimulating Aβ deposition and tau protein tangles. Indirectly, abnormal lipids can increase the burden on brain vasculature, induce insulin resistance, and affect the structure of neuronal cell membranes. Abnormal lipid metabolism leads to PD through inducing accumulation of α-syn, dysfunction of mitochondria and endoplasmic reticulum, and ferroptosis. Great progress has been made in targeting lipid metabolism abnormalities for the treatment of AD and PD in recent years, like metformin, insulin, peroxisome proliferator-activated receptors (PPARs) agonists, and monoclonal antibodies targeting apolipoprotein E (ApoE). This review comprehensively summarizes the involvement of dysregulated lipid metabolism in the pathogenesis of AD and PD, the application of Lipid Monitoring, and emerging lipid regulatory drug targets. A better understanding of the lipidological bases of AD and PD may pave the way for developing effective prevention and treatment methods for neurodegenerative disorders.

Uric Acid Mitigates Cognitive Deficits via TFEB-Mediated Microglial Autophagy in Mice Models of Alzheimer's Disease

Clinical trials have demonstrated the potential neuroprotective effects of uric acid (UA) in Alzheimer's disease (AD). However, the specific mechanism underlying the neuroprotective effect of UA remains unclear. In the present study, we investigated the neuroprotective effect and underlying mechanism of UA in AD mouse models. Various behavioral tests including an elevated plus maze, Barnes maze, and Morris water maze were conducted to evaluate the impact of UA on cognitive function in β-amyloid (Aβ) microinjection and APP23/PS45 double transgenic mice models of AD. Immunohistochemical staining was employed to visualize pathological changes in the brains of AD model mice. Western blotting and immunofluorescence techniques were used to assess levels of autophagy-related proteins and transcription factor EB (TFEB)-related signaling pathways. BV2 cells were used to investigate the association between UA and microglial autophagy. We reported that UA treatment significantly alleviated memory decline in Aβ-induced AD model mice and APP23/PS45 double transgenic AD model mice. Furthermore, UA activated microglia and upregulated the autophagy-related proteins such as LC3II/I ratio, Beclin-1, and LAMP1 in the hippocampus of AD model mice. Similarly, UA protected BV2 cells from Aβ toxicity by upregulating the expressions of Beclin-1, LAMP1, and the LC3II/I ratio, whereas genetic inhibition of TFEB completely abolished these protective effects. Our results indicate that UA may serve as a novel activator of TFEB to induce microglia autophagy and facilitate Aβ degradation, thereby improving cognitive function in AD model mice. Therefore, these findings suggest that UA may be a novel therapeutic agent for AD treatment.

Impact of TRPV1 on Pathogenesis and Therapy of Neurodegenerative Diseases

Transient receptor potential vanilloid 1 (TRPV1) is a transmembrane and non-selective cation channel protein, which can be activated by various physical and chemical stimuli. Recent studies have shown the strong pathogenetic associations of TRPV1 with neurodegenerative diseases (NDs), in particular Alzheimer's disease (AD), Parkinson's disease (PD) and multiple sclerosis (MS) via regulating neuroinflammation. Therapeutic effects of TRPV1 agonists and antagonists on the treatment of AD and PD in animal models also are emerging. We here summarize the current understanding of TRPV1's effects and its agonists and antagonists as a therapeutic means in neurodegenerative diseases, and highlight future treatment strategies using natural TRPV1 agonists. Developing new targets and applying natural products are becoming a promising direction in the treatment of chronic disorders, especially neurodegenerative diseases.

Metabolic regulation of microglial phagocytosis: Implications for Alzheimer's disease therapeutics

Microglia, the resident immune cells of the brain, are increasingly implicated in the regulation of brain health and disease. Microglia perform multiple functions in the central nervous system, including surveillance, phagocytosis and release of a variety of soluble factors. Importantly, a majority of their functions are closely related to changes in their metabolism. This natural inter-dependency between core microglial properties and metabolism offers a unique opportunity to modulate microglial activities via nutritional or metabolic interventions. In this review, we examine the existing scientific literature to synthesize the hypothesis that microglial phagocytosis of amyloid beta (Aβ) aggregates in Alzheimer's disease (AD) can be selectively enhanced via metabolic interventions. We first review the basics of microglial metabolism and the effects of common metabolites, such as glucose, lipids, ketone bodies, glutamine, pyruvate and lactate, on microglial inflammatory and phagocytic properties. Next, we examine the evidence for dysregulation of microglial metabolism in AD. This is followed by a review of in vivo studies on metabolic manipulation of microglial functions to ascertain their therapeutic potential in AD. Finally, we discuss the effects of metabolic factors on microglial phagocytosis of healthy synapses, a pathological process that also contributes to the progression of AD. We conclude by enlisting the current challenges that need to be addressed before strategies to harness microglial phagocytosis to clear pathological protein deposits in AD and other neurodegenerative disorders can be widely adopted.