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

Integrative metabolomics and transcriptomics analysis of hippocampus reveals taurine metabolism and sphingolipid metabolism dysregulation associated with sleep deprivation-induced memory impairment

Sleep plays a crucial role in restoring and repairing the body, consolidating memory, regulating emotions, maintaining metabolic and so on. Sleep deprivation is known to impair cognitive functions. In this study, we investigated the mechanisms underlying memory impairment induced by sleep deprivation through a combined metabolomic and transcriptomic analysis of hippocampus. Eight-week-old mice were selected as the study subjects and the sleep deprivation chamber was used to establish a sleep deprivation model. Novel object recognition tests (NOR), and Y-maze tests were used to assess the behavioral outcomes in mice. The hippocampus were extracted and studied using the untargeted metabolomics or transcriptomics high-throughput sequencing method. An integrative analysis was conducted to elucidate the metabolic and genetic changes. Behavioral tests showed that sleep-deprived mice exhibited memory impairment. Metabolomic analysis identified 84 differentially expressed metabolites (DEMs), including 12 under the positive ion mode and 72 under the negative ion mode. The analysis revealed that sleep deprivation caused abnormalities in several metabolic pathways, with particularly pronounced effects observed in glycerophospholipid metabolism, linoieic acid metabolism, alanine, aspartate, glutamate metabolism, taurine and hypotaurine metabolism, and purine metabolism. While transcriptomic analysis releaved 97 differentially expressed genes (DEGs) (51 were down-regulated and 46 were up-regulated DEGs). Integrative analysis of the metabolomic and transcriptomic identified profiles showed that sleep deprivation may regulate taurine and hypotaurine metabolism and sphingolipid metabolism, there by influencing memory. Our results prompt severe metabolic disturbances occur in the hippocampus with sleep deprivation in mice, which can provide a basis for the mechanism research.

Causal relationship between gut microbiota, lipids, and neuropsychiatric disorders: A Mendelian randomization mediation study

BACKGROUND

Numerous studies have shown an interconnection between the gut microbiota and the brain via the "gut-brain" axis. However, the causal relationships between gut microbiota, lipids, and neuropsychiatric disorders remain unclear. This study aimed to analyze potential associations among gut microbiota, lipids, and neuropsychiatric disorders-including AD, PD, ALS, MS, SCZ, MDD, and BD-using summary data from large-scale GWAS.

METHODS

Bidirectional Mendelian randomization (MR) with inverse variance weighting (IVW) was the primary method. Supplementary analyses included sensitivity analyses, Steiger tests, and Bayesian weighted MR (BWMR). Mediation analyses used two-step MR (TSMR) and multivariable MR (MVMR).

RESULTS

The analyses revealed 51 positive correlations (risk factors) (β > 0, P < 0.05) and 47 negative correlations (protective factors) (β < 0, P < 0.05) between gut microbiota and neuropsychiatric disorders. In addition, 35 positive correlations (β > 0, P < 0.05) and 22 negative correlations (β < 0, P < 0.05) between lipids and neuropsychiatric disorders were observed. Assessment of reverse causality with the seven neuropsychiatric disorders as exposures and the identified gut microbiota and lipids as outcomes revealed no evidence of reverse causality (P > 0.05). Mediation analysis indicated that the effect of the species Bacteroides plebeius on MDD is partially mediated through the regulation of phosphatidylcholine (16:0_20:4) levels (mediation proportion = 10.9 % [95 % CI = 0.0110-0.2073]).

CONCLUSION

This study provides evidence of a causal relationship between gut microbiota and neuropsychiatric disorders, suggesting lipids as mediators. These findings offer new insights into the mechanisms by which gut microbiota may influence neuropsychiatric disorders.

Proinflammatory and GABA eating bacteria in Parkinson's disease gut microbiome from a meta-analysis prospective

Parkinson's disease (PD) is the second most common neurodegenerative disorder, characterized by motor dysfunction coupled with gastrointestinal disturbances. Recent studies implicate the gut microbiome with the development of PD, yet pinpointing the exact microbial players is still to be determined. This meta-analysis is the first to consolidate five homogenous case-control studies, covering the same variable regions of the 16S rRNA of 1007 fecal samples. Utilizing our unified pipeline, we identified several key players potentially contributing to PD. Our findings reveal higher microbial diversity characterized by elevated levels GABA consuming species particularly Evtepia gabavorous, contributing to neuronal excitability. We also report the abundance of the proinflammatory Klebsiella variicola and the H2S-producing Streptococcus anginosus bacteria, potentially promoting α-synuclein accumulation in the brain. This comprehensive analysis highlights the potential of gut microbiota as a biomarker and a therapeutic strategy to mitigate the progression of PD, possibly facilitating diagnosis and enhancing patient outcomes.

Lipid metabolism in health and disease: Mechanistic and therapeutic insights for Parkinson's disease

ABSTRACT

Parkinson's disease (PD) is a neurodegenerative disorder characterized by the progressive loss of dopaminergic neurons and the accumulation of Lewy bodies, leading to motor and nonmotor symptoms. While both genetic and environmental factors contribute to PD, recent studies highlight the crucial role of lipid metabolism disturbances in disease progression. Altered lipid homeostasis promotes protein aggregation and oxidative stress, with significant changes in lipid classes such as sphingolipids and glycerolipids observed in patients with PD. These disturbances are involved in key pathological processes, such as α-synuclein aggregation, organelle dysfunction, lipid-mediated neuroinflammation, and impaired lipid homeostasis. This review examines the relationship between lipid species and PD progression, focusing on the physiological roles of lipids in the central nervous system. It explores the mechanistic links between lipid metabolism and PD pathology, along with lipid-related genetic risk factors. Furthermore, this review discusses lipid-targeting therapeutic strategies to mitigate PD progression, emphasizing the potential of lipid modulation for effective treatment development.

Nose-to-brain drug delivery: from bench to bedside

There is increasing interest in nose-to-brain delivery as an innovative drug delivery strategy for neurodegenerative disorders such as Parkinson's or Alzheimer's disease. The unique anatomy of the nose-brain interface facilitates direct drug transport via the olfactory and trigeminal pathways to the brain, bypassing the blood-brain barrier. Different administration techniques as well as advanced drug formulations like targeted nanoparticles and thermoresponsive systems have been explored to improve the delivery efficiency and the therapeutic efficacy. This review provides an up-to-date perspective on this fast-developing field, and discusses different studies on safety and pharmacokinetic properties. A thorough evaluation of preclinical and clinical studies reveals both promises and challenges of this delivery method, highlighting approved drugs for the treatment of epilepsy and migraine that successfully utilize intranasal routes. The current landscape of research on nose-to-brain delivery is critically discussed, and a rationale is provided for ongoing research to optimize therapeutic strategies.

HucMSCs-Derived Extracellular Vesicles Deliver RPS27A Protein to Manipulate the MDM2-P53 Axis and Ameliorate Neurological Dysfunction in Parkinson's Disease

Extracellular vesicles released from mesenchymal stem cells (MSCs-EV) have shown anti-inflammatory effects in Parkinson's disease (PD). This study was designed to assess the neuroprotective effects of human umbilical cord MSCs (hucMSCs) and the possible mechanisms involved. SH-SY5Y cells were induced with MPP+, and the impact of hucMSCs-EV on the damage to SH-SY5Y cells was examined. Mice were induced with PD-like symptoms by MPTP and the effects of hucMSCs-EV on neurological damage in mouse brain tissue were detected as well. HucMSCs-EV inhibited apoptosis and oxidative stress in MPP+-induced SH-SY5Y cells. HucMSCs-EV suppressed behavioral deficits and neuronal apoptosis in MPTP-induced mice, with an increased number of dopamine neurons in brain tissues and decreased p-alpha-syn expression in dopamine neurons. The expression of ribosomal protein S27A (RPS27A) in SH-SY5Y cells was elevated after co-culture of neurons and hucMSCs-EV, and RPS27A silencing abated the effect of hucMSCs-EV in vivo and in vitro. RPS27A bound to the MDM2 promoter, thus promoting P53 ubiquitination and degradation. MDM2 overexpression strengthened the therapeutic effect of hucMSCs-EV. We conclude that hucMSCs-EV promote the interaction between RPS27A and MDM2 by delivering RPS27A, which regulates the MDM2-P53 axis to promote degradation of P53 to ameliorate neurological damage in PD.

Novel Pyrido[3,4-d]pyrimidin-4-one and Pyrimido[5,4-d]pyrimidin-4-one Derivatives as TREM2 Agonists for Treating Parkinson's Disease

Provided herein are novel pyrido[3,4-d]pyrimidin-4-one and pyrimido[5,4-d]pyrimidin-4-one derivatives as TREM2 agonists, pharmaceutical compositions, use of such compounds in treating Parkinson's disease, and processes for preparing such compounds.

Mechanistic insights into impaired β-oxidation and its role in mitochondrial dysfunction: A comprehensive review

Mitochondria, also known as the powerhouse of cells, have an important role in cellular metabolism and energy production. However, during Mitochondrial Dysfunction (MD), it is known to generate reactive oxidative species and induce cellular apoptosis. A number of research findings have linked MD to various diseases, highlighting its critical role in maintaining health and contributing to disease development. In this regard, recent research has revealed that disruptions in lipid metabolism, especially in fatty acid oxidation, are significant contributors to MD. However, the precise mechanisms by which these defects lead to disease remain poorly understood. This review explores how disruptions in lipid metabolism are responsible for triggering oxidative stress, inflammation, and cellular damage, leading to impaired mitochondrial function. By examining specific fatty acid oxidation disorders, such as carnitine palmitoyltransferase deficiency, medium-chain acyl-CoA dehydrogenase deficiency, and very long-chain acyl-CoA dehydrogenase deficiency, this review aims to uncover the underlying molecular pathways connecting lipid metabolism to mitochondrial dysfunction. Furthermore, MD is a common underlying mechanism in a wide array of diseases, including neurodegenerative disorders and metabolic syndromes. Understanding the mechanisms behind mitochondrial malfunction may aid in the development of tailored therapies to restore mitochondrial health and treat intricate health conditions.

A Lipidomic Approach to Studying the Downregulation of Free Fatty Acids by Cytosolic Phospholipase A2 Inhibitors

Inhibitors of cytosolic phospholipase A2 (GIVA cPLA2) have received great attention, since this enzyme is involved in a number of inflammatory diseases, including cancer and auto-immune and neurodegenerative diseases. Traditionally, the effects of GIVA cPLA2 inhibitors in cells have been studied by determining the inhibition of arachidonic acid release. However, although to a lesser extent, GIVA cPLA2 may also hydrolyze glycerophospholipids, releasing other free fatty acids (FFAs), such as linoleic acid or oleic acid. In the present work, we applied a liquid chromatography-high-resolution mass spectrometry method to study the levels of intracellular FFAs, after treating cells with selected GIVA cPLA2 inhibitors. Six inhibitors belonging to different chemical classes were studied, using SH-SY5Y neuroblastoma cells as a model. This lipidomic approach revealed that treatment with each inhibitor created a distinct intracellular FFA profile, suggesting not only inhibitory potency against GIVA cPLA2, but also other parameters affecting the outcome. Potent inhibitors were found to reduce not only arachidonic acid, but also other long-chain FAs, such as adrenic or linoleic acid, even medium-chain FAs, such as caproic or caprylic acid, suggesting that GIVA cPLA2 inhibitors may affect FA metabolic pathways in general. The downregulation of intracellular FFAs may have implications in reprogramming FA metabolism in neurodegenerative diseases and cancer.

Therapeutic Potential of Mesenchymal Stem Cell-Derived Extracellular Vesicles in the Treatment of Parkinson's Disease

Parkinson's disease (PD) is a progressive neurodegenerative disorder characterized by the gradual loss of dopamine-producing neurons. Oxidative stress, mitochondrial dysfunction, detrimental immune response, and neuroinflammation are mainly responsible for the injury and degeneration of dopaminergic neurons in the brains of patients suffering from PD. Mesenchymal stem cell-derived extracellular vesicles (MSC-EVs) have emerged as a promising therapeutic approach for treating PD due to their ability to suppress the activation of inflammatory immune cells and enhance the viability and function of dopamine-producing neurons. MSC-EVs can easily bypass the blood-brain barrier and deliver their cargo (neuroprotective factors, immunosuppressive proteins, and microRNAs) to injured dopamine-producing neurons and brain-infiltrated inflammatory immune cells. A large number of recently published experimental studies demonstrated that MSC-EVs efficiently alleviated PD-related motor and behavioral deficits in animal models, indicating that MSC-EVs should be considered as potentially new therapeutic agents for the treatment of PD. Accordingly, in this review article, we summarized current knowledge about the therapeutic potential of MSCs-EVs in the treatment of PD, paving the way for their future clinical use in the treatment of neurodegenerative and neuroinflammatory disorders.

Time restricted feeding alters the behavioural and physiological outcomes to repeated mild traumatic brain injury in male and female rats

Mild traumatic brain injury (mTBI) research has had limited success translating treatments from preclinical models to clinical application for concussion. One major factor that has been overlooked is the near 24-hour availability of food, both for experimental nocturnal rodents and patients suffering from mTBI. Here, we characterised the impact of food restriction limited to either the inactive (day) or the active phase (night), on repetitive mTBI (RmTBI) - induced outcomes in male and female rats. We found that active phase fed rats consumed more food, had increased body weight, and reduced brain weights. Behaviourally, active phase feeding increased motor coordination deficits and caused changes to thermal nociceptive processing following RmTBI. Hypothalamic transcriptomic analysis revealed minor changes in response to RmTBI, and genes associated with oxytocin-vasopressin regulation in response to inactive phase, but not active phase feeding. These transcript changes were absent in females, where the overall effect of RmTBI was minor. Prefrontal cortex lipidomics revealed an increase in sphingomyelin synthesis following injury and marked sex differences in response to feeding. Of the lipids that changed and overlapped between the prefrontal cortex and serum, dihydroceramides, sphingomyelins, and hexosylceramides, were higher in the serum but lower in the prefrontal cortex. Together, these results demonstrate that feeding time alters outcomes to RmTBI, independent of the hypothalamic transcriptome, and injury-specific lipids may serve as useful biomarkers in RmTBI diagnosis.

The Inflammatory Mechanism of Parkinson's Disease: Gut Microbiota Metabolites Affect the Development of the Disease Through the Gut-Brain Axis

Parkinson's disease is recognized as the second most prevalent neurodegenerative disorder globally, with its incidence rate projected to increase alongside ongoing population growth. However, the precise etiology of Parkinson's disease remains elusive. This article explores the inflammatory mechanisms linking gut microbiota to Parkinson's disease, emphasizing alterations in gut microbiota and their metabolites that influence the disease's progression through the bidirectional transmission of inflammatory signals along the gut-brain axis. Building on this mechanistic framework, this article further discusses research methodologies and treatment strategies focused on gut microbiota metabolites, including metabolomics detection techniques, animal model investigations, and therapeutic approaches such as dietary interventions, probiotic treatments, and fecal transplantation. Ultimately, this article aims to elucidate the relationship between gut microbiota metabolites and the inflammatory mechanisms underlying Parkinson's disease, thereby paving the way for novel avenues in the research and treatment of this condition.

Evolution of Alzheimer's Disease Therapeutics: From Conventional Drugs to Medicinal Plants, Immunotherapy, Microbiotherapy and Nanotherapy

Alzheimer's disease (AD) represents an escalating global health crisis, constituting the leading cause of dementia among the elderly and profoundly impairing their quality of life. Current FDA-approved drugs, such as rivastigmine, donepezil, galantamine, and memantine, offer only modest symptomatic relief and are frequently associated with significant adverse effects. Faced with this challenge and in line with advances in the understanding of the pathophysiology of this neurodegenerative condition, various innovative therapeutic strategies have been explored. Here, we review novel approaches inspired by advanced knowledge of the underlying pathophysiological mechanisms of the disease. Among the therapeutic alternatives, immunotherapy stands out, employing monoclonal antibodies to specifically target and eliminate toxic proteins implicated in AD. Additionally, the use of medicinal plants is examined, as their synergistic effects among components may confer neuroprotective properties. The modulation of the gut microbiota is also addressed as a peripheral strategy that could influence neuroinflammatory and degenerative processes in the brain. Furthermore, the therapeutic potential of emerging approaches, such as the use of microRNAs to regulate key cellular processes and nanotherapy, which enables precise drug delivery to the central nervous system, is analyzed. Despite promising advances in these strategies, the incidence of Alzheimer's disease continues to rise. Therefore, it is proposed that achieving effective treatment in the future may require the integration of combined approaches, maximizing the synergistic effects of different therapeutic interventions.

Revolutionizing Neuroimmunology: Unraveling Immune Dynamics and Therapeutic Innovations in CNS Disorders

Neuroimmunology is reshaping the understanding of the central nervous system (CNS), revealing it as an active immune organ rather than an isolated structure. This review delves into the unprecedented discoveries transforming the field, including the emerging roles of microglia, astrocytes, and the blood-brain barrier (BBB) in orchestrating neuroimmune dynamics. Highlighting their dual roles in both repair and disease progression, we uncover how these elements contribute to the intricate pathophysiology of neurodegenerative diseases, cerebrovascular conditions, and CNS tumors. Novel insights into microglial priming, astrocytic cytokine networks, and meningeal lymphatics challenge the conventional paradigms of immune privilege, offering fresh perspectives on disease mechanisms. This work introduces groundbreaking therapeutic innovations, from precision immunotherapies to the controlled modulation of the BBB using nanotechnology and focused ultrasound. Moreover, we explore the fusion of immune modulation with neuromodulatory technologies, underscoring new frontiers for personalized medicine in previously intractable diseases. By synthesizing these advancements, we propose a transformative framework that integrates cutting-edge research with clinical translation, charting a bold path toward redefining CNS disease management in the era of precision neuroimmunology.

Transcriptome Signatures for Cognitive Resilience Among Individuals with Pathologically Confirmed Alzheimer Disease

INTRODUCTION

Limited success to date in development of drugs that target hallmark Alzheimer disease (AD) proteins as a means to slow AD-related cognitive decline has sparked interest in approaches focused on cognitive resilience. We sought to identify transcriptome signatures among brain donors with neuropathologically confirmed AD that distinguish those with cognitive impairment from those that were cognitively intact.

METHODS

We compared gene expression patterns in brain tissue from donors in four cohorts who were cognitively and pathologically normal (controls), met clinical and pathological criteria for AD (SymAD), or were cognitively normal prior to death despite pathological evidence of AD (cognitively resilient or AsymAD). Differentially expressed genes (DEGs) at the transcriptome-wide significance (TWS) level (P<10 -6 ) in the total sample and nominally significant (P<0.05) in at least two datasets were further evaluated in analyses testing association of gene expression with co-calibrated and harmonized cognitive domain scores and AD-related neuropathological traits.

RESULTS

We identified 52 TWS DEGs, including 14 that surpassed a significance threshold of P<5×10 -8 . The three most significant DEGs, ADAMTS2 (Log2 fold change [Log2FC]=0.46, P=2.94×10 -14 ), S100A4 (Log2FC=0.61, P=3.98×10 -11 ) and NRIP2 (Log2FC=0.32, P=9.52×10 -11 ) were up-regulated in SymAD compared to AsymAD brains. ADAMTS2 and SLC6A9 were also significantly and nominally differentially expressed between AsymAD cases and controls (FDR P=0.45 and FDR P=0.57, respectively). Significant associations (P<0.0038) were identified for executive function with expression of ADAMTS2 (P=4.15×10 -8 ) and ARSG (P=1.09×10 -3 ), and for memory with PRELP (P=3.92×10 -5 ) and EMP3 (P=7.75×10 -4 ), and for language with SLC38A2 (P=6.76×10 -5 ) and SLC6A9 (P=2.13 ×10 -3 ). Expression of ARSG and FHIP1B were associated with measures of Tau pathology (AT8: P=1.5×10 -3 , and pTau181: P=3.64×10 -3 , respectively), and SLC6A9 expression was associated with multiple pTau isoforms including pTau181 (P=1.5×10 -3 ) and pTau396 (P=2.05×10 -3 ). PRELP expression was associated with synaptic density (PSD.95: P=6.18 ×10 -6 ). DEGs were significantly enriched in pathways involving E2F targets, cholesterol homeostasis, and oxidative phosphorylation.

CONCLUSION

We identified multiple DEGs that differentiate neuropathologically confirmed AD cases with and without cognitive impairment prior to death. Expression of several of these genes was also associated with measures of cognitive performance and AD-related neuropathological traits, thus providing important insights into cognitive resilience mechanisms and strategies for delaying clinical symptoms of AD.

Underneath the Gut-Brain Axis in IBD-Evidence of the Non-Obvious

The gut-brain axis (GBA) plays a pivotal role in human health and wellness by orchestrating complex bidirectional regulation and influencing numerous critical processes within the body. Over the past decade, research has increasingly focused on the GBA in the context of inflammatory bowel disease (IBD). Beyond its well-documented effects on the GBA-enteric nervous system and vagus nerve dysregulation, and gut microbiota misbalance-IBD also leads to impairments in the metabolic and cellular functions: metabolic dysregulation, mitochondrial dysfunction, cationic transport, and cytoskeleton dysregulation. These systemic effects are currently underexplored in relation to the GBA; however, they are crucial for the nervous system cells' functioning. This review summarizes the studies on the particular mechanisms of metabolic dysregulation, mitochondrial dysfunction, cationic transport, and cytoskeleton impairments in IBD. Understanding the involvement of these processes in the GBA may help find new therapeutic targets and develop systemic approaches to improve the quality of life in IBD patients.

Associations of human blood metabolome with optic neurodegenerative diseases: a bi-directionally systematic mendelian randomization study

BACKGROUND

Metabolic disruptions were observed in patients with optic neurodegenerative diseases (OND). However, evidence for the causal association between metabolites and OND is limited.

METHODS

Two-sample Mendelian randomization (MR). Summary data for 128 blood metabolites was selected from three genome-wide association study (GWASs) involving 147,827 participants of European descent. GWASs Data for glaucoma (20906 cases and 391275 controls) and age-related macular degeneration (AMD, 9721 cases and 381339 controls) came from FinnGen consortium. A bi-directional MR was conducted to assess causality, and a Mediation MR was further applied to explore the indirect effect, a phenome-wide MR analysis was then performed to identify possible side-effects of the therapies.

RESULTS

All the results underwent correction for multiple testing and rigorous sensitivity analyses. We identified N-acetyl glycine, serine, uridine were linked to an elevated risk of glaucoma. 1-arachidonic-glycerol-phosphate-ethanolamine, 4-acetamido butanoate, o-methylascorbate, saturated fatty acids, monounsaturated fatty acids, VLDL cholesterol, serum total cholesterol, X-11,529 were linked to reduced risk of glaucoma. There were 4 metabolites linked to a reduced risk of AMD, including tryptophan betaine, 4-androsten-3beta-17beta-diol disulfate, apolipoprotein B, VLDL cholesterol. We discovered IOP, AS, T2D as glaucoma risk factors, while BMI, AS, GCIPL as AMD factors. And 6 metabolites showed associations with risk factors in the same direction as their associations with glaucoma/AMD. Phenome-wide MR indicated that selected metabolites had protective/adverse effects on other diseases.

CONCLUSIONS

By integrating genomics and metabolomics, this study supports new insights into the intricate mechanisms, and helps prevent and screen glaucoma and AMD.

Single-cell RNA sequencing reveals peripheral immunological features in Parkinson's Disease

Although many researchers of Parkinson's disease (PD) have shifted their focus from the central nervous system (CNS) to the peripheral blood, a significant knowledge gap remains between PD severity and the peripheral immune response. In the current study, we aimed to map the peripheral immunity atlas in peripheral blood mononuclear cells (PBMCs) from PD patients and healthy controls using single-cell RNA sequencing (scRNA-seq). Our study employed scRNA-seq analysis to map the peripheral immunity atlas in PD by profiling PBMCs from PD-Early, PD-Late patients and matched controls. By enlarging the blood sample size, we validated the roles of NK cells in numerous immune-related biological processes. We also detected the infiltration of NK cells into the cerebral motor cortex as the disease progressed, using human brain sections, and elucidated the communication between the periphery and CNS and its implications for PD. As a result, cell subpopulation atlases in PBMCs from PD patients and healthy controls along with differentially expressed genes in NK cells were identified by scRNA-seq analysis, representing 6 major immune cell subsets among which NK cells declined in the progression of PD. We further validated NK cell reduction in increasing samples and found that they participated in numerous immune-related biological processes and infiltration into the cerebral motor cortex as the disease proceeded, evidencingd the close communication between the peripheral immune response and CNS. Strikingly, XCL2 positively correlated with PD severity, with good predictive performance of PD and specific expression in subclusters C2 and C5 of NK cells. All these findings delineated the critical role of peripheral immune response mediated by NK cells in the pathogenesis of PD. NK cell-specific XCL2 could be used as a diagnostic marker for treating PD. The indispensable function of NK cells and NK cell-specific molecular biomarkers highlighted the implication of the peripheral immune response in PD progression. Trial registration: ChiCTR, ChiCTR1900023975. Registered 20 June 2019 - Retrospectively registered, https://www.chictr.org.cn/showproj.html?proj=31035 .

Omega-3 polyunsaturated fatty acids and Parkinson's disease: A systematic review of animal studies

Parkinson's disease (PD) is the second most common neurodegenerative disorder. The primary pathological features of PD include the presence of α-synuclein aggregates and Lewy bodies, mitochondrial dysfunction, oxidative stress, and neuroinflammation. Recently, omega-3 fatty acids (ω-3 PUFAs) have been under investigation as a preventive and/or therapeutic strategy for PD, primarily owing to their antioxidant and anti-inflammatory properties. Therefore, the objective of this study was to conduct a systematic review of the literature, focusing on studies that assessed the effects of ω-3 PUFAs in rodent models mimicking human PD. The search was performed using the terms "Parkinson's disease," "fish oil," "omega 3," "docosahexaenoic acid," and "eicosapentaenoic acid" across databases PUBMED, Web of Science, Science Direct, Scielo, and Google Scholar. Following analysis based on predefined inclusion and exclusion criteria, 39 studies were included. Considering behavioral parameters, pathological markers of the disease, quantification of ω-3 PUFAs in the brain, as well as anti-inflammatory, antioxidant, and anti-apoptotic effects, it can be observed that ω-3 PUFAs exhibit a potential neuroprotective effect in PD. In summary, this systematic review presents significant scientific evidence regarding the effects and mechanisms underlying the neuroprotective properties of ω-3 PUFAs, offering valuable insights for the development of future clinical investigations.