Neuroinflammation in Parkinson's disease and its potential as therapeutic target

GLP-1 analogue liraglutide attenuates CIH-induced cognitive deficits by inhibiting oxidative stress, neuroinflammation, and apoptosis via the Nrf2/HO-1 and MAPK/NF-κB signaling pathways

Obstructive sleep apnea (OSA) is a common clinical condition linked to cognitive impairment, mainly characterized by chronic intermittent hypoxia (CIH). GLP-1 receptor agonist, known for promoting insulin secretion and reducing glucose levels, has demonstrated neuroprotective effects in various experimental models such as stroke, Alzheimer's disease, and Parkinson's disease. This study aims to investigate the potential role and mechanisms of the GLP-1 receptor agonist liraglutide in ameliorating OSA-induced cognitive deficits. CIH exposure, a well-established and mature OSA pathological model, was used both in vitro and in vivo. In vitro, CIH significantly activated oxidative stress, inflammation, and apoptosis in SH-SY5Y cells. Liraglutide enhanced the nuclear translocation of Nrf2, activating its downstream pathways, thereby mitigating CIH-induced injury in SH-SY5Y cells. Additionally, liraglutide modulated the MAPK/NF-κB signaling pathway, reducing the expression of inflammatory factors and proteins. In vivo, we subjected mice to an intermittent hypoxia incubator to mimic the pathogenesis of human OSA. The Morris water maze test revealed that CIH exposure substantially impaired spatial memory. Subsequent western blot analyses and histopathological examinations indicated that liraglutide could activate the Nrf2/HO-1 axis and inhibit the MAPK/NF-κB signaling pathway, thereby alleviating OSA-associated cognitive dysfunction in mice. These findings suggest that GLP-1 receptor agonists may offer a promising preventive strategy for OSA-associated cognitive impairment. By refining these findings, we provide new insights into GLP-1's protective mechanisms in combating cognitive deficits associated with CIH, underscoring its potential as a therapeutic agent for conditions linked to OSA.

NR1H4 ameliorates Parkinson's disease via inhibiting astrocyte activation and neuroinflammation in a CEBPβ/NF-κB dependent manner

Parkinson's Disease (PD) is a degenerative disease driven by neuroinflammation. Nuclear receptor subfamily 1 group H member 4 (NR1H4), a nuclear receptor involved in metabolic and inflammatory regulation, is found to be widely expressed in central nervous system. Previous studies suggested the protective role of NR1H4 in various diseases related to inflammation, whether NR1H4 participates in PD progression remains unknown. To investigate the role of NR1H4 in neuroinflammation regulation, especially astrocyte activation during PD, siRNA and adenovirus were used to manipulate Nr1h4 expression. RNA-sequencing (RNA-seq), quantitative real-time PCR, enzyme-linked immunosorbent assay, Chromatin immunoprecipitation and western blotting were performed to further study the underlying mechanisms. We identified that NR1H4 was down-regulated during PD progression. In vitro experiments suggested that Nr1h4 knockdown led to inflammatory response, reactive oxygen species generation and astrocytes activation whereasNr1h4 overexpressionhad the opposite effects. The results of RNA-seq on astrocytes revealed that NR1H4 manipulated neuroinflammation in a CEBPβ/NF-κB dependent manner. Additionally, pharmacological activation of NR1H4 via Obeticholic acid ameliorated neuroinflammation and promoted neuronal survival. Our study first proved the neuroprotective effects of NR1H4against PD via inhibiting astrocyte activation and neuroinflammation in a CEBPβ/NF-κB dependent manner.

Research progress in the mechanisms and functions of specialized pro-resolving mediators in neurological diseases

The nervous system interacts with the immune system through a variety of cellular regulators, signaling pathways, and molecular mechanisms. Disruptions in these interactions lead to the development of multiple neurological diseases. Recent studies have identified that specialized pro-resolving mediators (SPMs) play a regulatory role in the neuroimmune system. This study reviews recent research on the function of SPMs in the inflammatory process and their association with the nervous system. The review aims to provide new perspectives for studying the pathogenesis of neurological diseases and identify novel targets for clinical therapy.

Cerebral biomimetic nano-drug delivery systems: A frontier strategy for immunotherapy

Brain diseases are a significant threat to human health, especially in the elderly, and this problem is growing as the aging population increases. Efficient brain-targeted drug delivery has been the greatest challenge in treating brain disorders due to the unique immune environment of the brain, including the blood-brain barrier (BBB). Recently, cerebral biomimetic nano-drug delivery systems (CBNDSs) have provided a promising strategy for brain targeting by mimicking natural biological materials. Herein, this review explores the latest understanding of the immune microenvironment of the brain, emphasizing the immune mechanisms of the occurrence and progression of brain disease. Several brain targeting systems are summarized, including cell-based, exosome-based, protein-based, and microbe-based CBNDSs, and their immunological mechanisms are highlighted. Moreover, given the rise of immunotherapy, the latest applications of CBNDSs in immunotherapy are also discussed. This review provides a comprehensive understanding of CBNDSs and serves as a guideline for immunotherapy in treating brain diseases. In addition, it provides inspiration for the future of CBNDSs.

Fluid biomarkers of chronic traumatic brain injury

Traumatic brain injury (TBI) is a leading cause of long-term disability across the world. Evidence for the usefulness of imaging and fluid biomarkers to predict outcomes and screen for the need to monitor complications in the acute stage is steadily increasing. Still, many people experience symptoms such as fatigue and cognitive and motor dysfunction in the chronic phase of TBI, where objective assessments for brain injury are lacking. Consensus criteria for traumatic encephalopathy syndrome, a clinical syndrome possibly associated with the neurodegenerative disease chronic traumatic encephalopathy, which is commonly associated with sports concussion, have been defined only recently. However, these criteria do not fit all individuals living with chronic consequences of TBI. The pathophysiology of chronic TBI shares many similarities with other neurodegenerative and neuroinflammatory conditions, such as Alzheimer disease. As with Alzheimer disease, advancements in fluid biomarkers represent one of the most promising paths for unravelling the chain of pathophysiological events to enable discrimination between these conditions and, with time, provide prediction modelling and therapeutic end points. This Review summarizes fluid biomarker findings in the chronic phase of TBI (≥6 months after injury) that demonstrate the involvement of inflammation, glial biology and neurodegeneration in the long-term complications of TBI. We explore how the biomarkers associate with outcome and imaging findings and aim to establish mechanistic differences in biomarker patterns between types of chronic TBI and other neurodegenerative conditions. Finally, current limitations and areas of priority for future fluid biomarker research are highlighted.

GPR40 agonist ameliorates neurodegeneration and motor impairment by regulating NLRP3 inflammasome in Parkinson's disease animal models

Parkinson's disease (PD) is characterized by the progressive degeneration of dopaminergic neurons in the substantia nigra (SN) and accumulation of intracellular α-synuclein (ɑ-syn) aggregates known as Lewy bodies and Lewy neurites. Levels of polyunsaturated fatty acids (PUFAs) have previously been shown to be reduced in the SN of PD patients. G protein-coupled receptor 40 (GPR40) serves as a receptor for PUFAs, playing a role in neurodevelopment and neurogenesis. Additionally, GPR40 has been implicated in several neuropathological conditions, such as apoptosis and inflammation, suggesting its potential as a therapeutic target in PD. In this study, we investigated the neuroprotective effects of the GPR40 agonist, TUG469 in PD models. Our results demonstrated that TUG469 reduces the neurotoxicity induced by 6-OHDA in SH-SY5Y cells. In 6-OHDA-induced PD model mice, TUG469 treatment improved motor impairment, preserved dopaminergic fibers and cell bodies in the striatum (ST) or SN, and attenuated 6-OHDA-induced microgliosis and astrogliosis in the brain. Furthermore, in a PD model involving the injection of mouse ɑ-syn fibrils into the brain (mPFFs-PD model), TUG469 treatment reduced the levels of pSer129 ɑ-syn, and decreased microgliosis and astrogliosis. Our investigation also revealed that TUG469 modulates inflammasome activation, apoptosis, and autophagy in the 6-OHDA-PD model, as evidenced by the results of RNA-seq and western blotting analyses. In summary, our findings highlight the neuroprotective effects of GPR40 agonists on dopaminergic neurons and their potential as therapeutic agents for PD. These results underscore the importance of targeting GPR40 in PD treatment, particularly in mitigating neuroinflammation and preserving neuronal integrity.

The TLR4/NF-κB/NLRP3 and Nrf2/HO-1 pathways mediate the neuroprotective effects of alkaloids extracted from Uncaria rhynchophylla in Parkinson's disease

ETHNOPHARMACOLOGICAL RELEVANCE

Parkinson's disease (PD) is the second most common neurodegenerative disorder with limited therapeutic options available. Neuroinflammation plays an important role in the occurrence and development of PD. Alkaloids extracted from Uncaria rhynchophylla (URA), have emerged as a potential neuroprotective agent because of its anti-inflammatory and anti-oxidant properties. Nevertheless, the underlying mechanism by which URA exerts neuroprotective effects in PD remains obscure.

AIM OF THE STUDY

The main aim of this study was to investigate the neuroprotective effects and underlying mechanism of URA in the treatment of PD through in vivo and in vitro models, focusing on the neuroinflammation and oxidative stress pathways.

MATERIALS AND METHODS

The protective effects of URA against PD were evaluated by neurobehavioral tests, immunohistochemistry, serum biochemical assays, and real-time quantitative polymerase chain reaction in 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine (MPTP)-induced PD mice. The role of the TLR4/NF-κB/NLRP3 pathway and the Nrf2/HO-1 pathway in URA-mediated effects was examined in lipopolysaccharide (LPS)-stimulated BV-2 microglial cells and a microglia-neuron coculture system.

RESULTS

URA significantly alleviated motor deficits and dopaminergic neurotoxicity, and reversed the abnormal secretion of inflammatory and oxidative stress factors in the serum of MPTP-induced mice. URA suppressed the gene expression of Toll-like receptor 4 (TLR4), NOD-like receptor protein 3, and cyclooxygenase 2 (COX2) in the striatum of PD mice. Further studies indicated that URA inhibited activation of the TLR4/NF-κB/NLRP3 pathway and enhanced activation of the Nrf2/HO-1 pathway, reduced reactive oxygen species (ROS) production, and reversed the secretion of inflammatory mediators in LPS-stimulated BV-2 microglial cells, thereby alleviating neuroinflammatory damage to SH-SY5Y neuronal cells.

CONCLUSION

URA exerted neuroprotective effects against PD mainly by the inhibition of the TLR4/NF-κB/NLRP3 pathway and activation of the Nrf2/HO-1 antioxidant pathway, highlighting URA as a promising candidate for PD treatment.

Polo-like kinase 2 promotes microglial activation via regulation of the HSP90α/IKKβ pathway

Polo-like kinase 2 (PLK2) is a serine/threonine protein kinase associated with the regulation of synaptic plasticity and centriole duplication. We identify PLK2 as a crucial early-response gene in lipopolysaccharide (LPS)-stimulated microglial cells. Knockdown or inhibition of PLK2 remarkably attenuates LPS-induced expression of proinflammatory factors in microglial cells by suppressing the inhibitor of nuclear factor kappa B kinase subunit beta (IKKβ)-nuclear factor (NF)-κB signaling pathway. We identify heat shock protein 90 alpha (HSP90α), a regulator of IKKβ activity, as a novel PLK2 substrate. Knockdown or pharmacological inhibition of HSP90α abolishes PLK2-mediated activation of NF-κB transcriptional activity and microglial inflammatory activation. Furthermore, phosphoproteomic analysis pinpoints Ser252 and Ser263 on HSP90α as novel phosphorylation targets of PLK2. Lastly, conditional knockout of PLK2 in microglial cells dramatically ameliorates neuroinflammation and subsequent dopaminergic neuron loss in an intracranial LPS-induced mouse Parkinson's disease (PD) model. The present study reveals that PLK2 promotes microglial activation through the phosphorylation of HSP90α and subsequent activation of the IKKβ-NF-κB signaling pathway.

Mitochondrial Dysfunction as a Potential Mechanism Mediating Cardiac Comorbidities in Parkinson's Disease

Individuals diagnosed with Parkinson's disease (PD) often exhibit heightened susceptibility to cardiac dysfunction, reflecting a complex interaction between these conditions. The involvement of mitochondrial dysfunction in the development and progression of cardiac dysfunction and PD suggests a plausible commonality in some aspects of their molecular pathogenesis, potentially contributing to the prevalence of cardiac issues in PD. Mitochondria, crucial organelles responsible for energy production and cellular regulation, play important roles in tissues with high energetic demands, such as neurons and cardiac cells. Mitochondrial dysfunction can occur in different and non-mutually exclusive ways; however, some mechanisms include alterations in mitochondrial dynamics, compromised bioenergetics, biogenesis deficits, oxidative stress, impaired mitophagy, and disrupted calcium balance. It is plausible that these factors contribute to the increased prevalence of cardiac dysfunction in PD, suggesting mitochondrial health as a potential target for therapeutic intervention. This review provides an overview of the physiological mechanisms underlying mitochondrial quality control systems. It summarises the diverse roles of mitochondria in brain and heart function, highlighting shared pathways potentially exhibiting dysfunction and driving cardiac comorbidities in PD. By highlighting strategies to mitigate dysfunction associated with mitochondrial impairment in cardiac and neural tissues, our review aims to provide new perspectives on therapeutic approaches.

Novel neuroprotective 5,6-dihydropyrido[2',1':2,3]imidazo[4,5-c]quinoline derivatives acting through cholinesterase inhibition and CB2 signaling modulation

A novel group of 5,6-dihydropyrido [2',1':2,3]imidazo [4,5-c]quinolines was prepared via a microwave assisted one-pot telescopic approach. The synthetic sequence involves the formation of an amine precursor of imidazo [1,2-a]pyridine via condensation and reduction under microwave irradiation. Subsequently, the Pictet-Spengler cyclisation reaction occurs with ketones (cyclic or acyclic) to obtain substituted 5,6-dihydropyrido [2',1':2,3]imidazo [4,5-c]quinolines in excellent yields. The compounds were tested as neuroprotective agents. Observed protection of neuron-like cells, SH-SY5Y differentiated with ATRA, in Parkinson's and Huntington's disease models inspired further mechanistic studies of protective activity against damage induced by 1-methyl-4-phenylpyridinium (MPP+), a compound causing Parkinson's disease. The novel compounds exhibit similar or higher potency than ebselen, an established drug with antioxidant activity, in the cells against MPP + -induced total cellular superoxide production and cell death. However, they exhibit a significantly higher capacity to reduce mitochondrial superoxide and preserve mitochondrial membrane potential. We also observed marked differences between a selected derivative and ebselen in terms of normalizing MPP + -induced phosphorylation of Akt and ERK1/2. The cytoprotective activity was abrogated when signaling through cannabinoid receptor CB2 was blocked. The compounds also inhibit both acetylcholine and butyrylcholine esterases. Overall the data show that novel 5,6-dihydropyrido [2',1':2,3]imidazo [4,5-c]quinoline have a broad cytoprotective activity which is mediated by several mechanisms including mitoprotection.

Copper and its isotopes: a brief overview of its implications in geology, environmental system, and human health

Copper, a malleable and ductile transition metal, possesses two stable isotopes. These copper isotopic composition data have recently found diverse applications in various fields and disciplines. In geology, copper isotopes serve as tracers that aid in investigating ore formation processes and the mechanisms of copper deposits Likewise, it has emerged as a valuable tracer in polluted environments. In plant biology, copper acts as an essential micronutrient crucial for photosynthesis, respiration, and growth. Copper isotopes contribute to understanding how plants uptake and dispense copper from the soil within their tissues. Similarly, in animals, copper serves as an essential trace element, playing a vital role in growth, white blood cell function, and enzyme activity. In humans, copper acts as an antioxidant, neutralising harmful free radicals within the body. It also helps in maintaining the nervous and immune system. Furthermore, copper isotopes find medical applications, particularly in cancer diagnostics, neurodegenerative diseases, and targeted radiotherapy. However, excessive copper can have detrimental effects in humans such as it can cause liver damage, nausea, and abdominal pain, whilst in plants it can affect the growth of plants, photosynthesis, and membrane permeability. This review emphasises the significance of copper and its isotopes in geology, the environment, and human health.

Coumarin-chalcone derivatives as dual NLRP1 and NLRP3 inflammasome inhibitors targeting oxidative stress and inflammation in neurotoxin-induced HMC3 and BE(2)-M17 cell models of Parkinson's disease

Background

In Parkinson's disease (PD) brains, microglia are activated to release inflammatory factors to induce the production of reactive oxygen species (ROS) in neuron, and vice versa. Moreover, neuroinflammation and its synergistic interaction with oxidative stress contribute to the pathogenesis of PD.

Methods

In this study, we investigated whether in-house synthetic coumarin-chalcone derivatives protect human microglia HMC3 and neuroblastoma BE(2)-M17 cells against 1-methyl-4-phenyl pyridinium (MPP+)-induced neuroinflammation and associated neuronal damage.

Results

Treatment with MPP+ decreased cell viability as well as increased the release of inflammatory mediators including cytokines and nitric oxide in culture medium, and enhanced expression of microglial activation markers CD68 and MHCII in HMC3 cells. The protein levels of NLRP3, CASP1, iNOS, IL-1β, IL-6, and TNF-α were also increased in MPP+-stimulated HMC3 cells. Among the four tested compounds, LM-016, LM-021, and LM-036 at 10 μM counteracted the inflammatory action of MPP+ in HMC3 cells. In addition, LM-021 and LM-036 increased cell viability, reduced lactate dehydrogenase release, ameliorated cellular ROS production, decreased caspase-1, caspase-3 and caspase-6 activities, and promoted neurite outgrowth in MPP+-treated BE(2)-M17 cells. These protective effects were mediated by down-regulating inflammatory NLRP1, IL-1β, IL-6, and TNF-α, as well as up-regulating antioxidative NRF2, NQO1, GCLC, and PGC-1α, and neuroprotective CREB, BDNF, and BCL2.

Conclusion

The study results strengthen the involvement of neuroinflammation and oxidative stress in PD pathogenic mechanisms, and indicate the potential use of LM-021 and LM-036 as dual inflammasome inhibitors in treating both NLRP1- and NLRP3-associated PD.

Unraveling neuroprotection in Parkinson's disease: Nrf2-Keap1 pathway's vital role amidst pathogenic pathways

Parkinson's disease (PD) is an age-related chronic neurological condition characterized by progressive degeneration of dopaminergic neurons and the presence of Lewy bodies, primarily composed of alpha-synuclein and ubiquitin. The pathophysiology of PD encompasses alpha-synuclein aggregation, oxidative stress, neuroinflammation, mitochondrial dysfunction, and impaired autophagy and ubiquitin-proteasome systems. Among these, the Keap1-Nrf2 pathway is a key regulator of antioxidant defense mechanisms. Nrf2 has emerged as a crucial factor in managing oxidative stress and inflammation, and it also influences ubiquitination through p62 expression. Keap1 negatively regulates Nrf2 by targeting it for degradation via the ubiquitin-proteasome system. Disruption of the Nrf2-Keap1 pathway in PD affects cellular responses to oxidative stress and inflammation, thereby playing a critical role in disease progression. In addition, the role of neuroinflammation in PD has gained significant attention, highlighting the interplay between immune responses and neurodegeneration. This review discusses the various mechanisms responsible for neuronal degeneration in PD, with a special emphasis on the neuroprotective role of the Nrf2-Keap1 pathway. Furthermore, it explores the implications of inflammopharmacology in modulating these pathways to provide therapeutic insights for PD.

Unlocking Hope: Therapeutic Advances and Approaches in Modulating the Wnt Pathway for Neurodegenerative Diseases

Neurodegenerative diseases (NDs) are conditions characterized by sensory, motor, and cognitive impairments due to alterations in the structure and function of neurons in the central nervous system (CNS). Despite their widespread occurrence, the exact causes of NDs remain largely elusive, and existing treatments fall short in efficacy. The Wnt signaling pathway is an emerging molecular pathway that has been linked to the development and progression of various NDs. Wnt signaling governs numerous cellular processes, such as survival, polarity, proliferation, differentiation, migration, and fate specification, via a complex network of proteins. In the adult CNS, Wnt signaling regulates synaptic transmission, plasticity, memory formation, neurogenesis, neuroprotection, and neuroinflammation, all essential for maintaining neuronal function and integrity. Dysregulation of both canonical and non-canonical Wnt signaling pathways contributes to neurodegeneration through various mechanisms, such as amyloid-β accumulation, tau protein hyperphosphorylation, dopaminergic neuron degeneration, and synaptic dysfunction, prompting investigations into Wnt modulation as a therapeutic target to restore neuronal function and prevent or delay neurodegenerative processes. Modulating Wnt signaling has the potential to restore neuronal function and impede or postpone neurodegenerative processes, offering a therapeutic approach for targeting NDs. In this article, the current knowledge about how Wnt signaling works in Alzheimer's disease and Parkinson's disease is discussed. Our study aims to explore the molecular mechanisms, recent discoveries, and challenges involved in developing Wnt-based therapies.

Discovery of novel SS-31 (d-Arg-dimethylTyr-Lys-Phe-NH2) derivatives as potent agents to ameliorate inflammation and increase mitochondrial ATP synthesis

Neuroinflammation and mitochondrial function are crucial for neuronal function and survival. SS-31 is a novel mitochondria-targeted peptide antioxidant that reduces mitochondrial reactive oxygen species production, increases ATP generation, protects the integrity of mitochondrial cristae and the mitochondrial respiratory chain, and reduces inflammatory responses. Exploring novel SS-31 derivatives is important for the treatment of neurodegenerative diseases. In this study, nineteen SS-31 derived peptides (5a-5s) were synthesized. Through cellular activity screening, we discovered that 5f and 5g exhibited significantly greater anti-inflammatory activity compared to SS-31, reducing LPS-induced TNF-α levels by 43% and 45%, respectively, at a concentration of 10 μM. Furthermore, treatment with 50 nM of 5f and 5g increased ATP synthesis by 42% and 41% in rotenone-induced HT22 cells and attenuated mitochondrial ROS production by preserving mitochondrial integrity. These findings demonstrate their direct protective effects on neuronal mitochondria. This work highlights the potential of 5f and 5g in the treatment of neurodegenerative diseases associated with inflammation and mitochondrial damage, offering a promising therapeutic avenue for mitochondrial-related conditions such as Alzheimer's disease.

Unveiling citicoline's mechanisms and clinical relevance in the treatment of neuroinflammatory disorders

Citicoline, a compound produced naturally in small amounts in the human body, assumes a pivotal role in phosphatidylcholine synthesis, a dynamic constituent of membranes of neurons. Across diverse models of brain injury and neurodegeneration, citicoline has demonstrated its potential through neuroprotective and anti-inflammatory effects. This review aims to elucidate citicoline's anti-inflammatory mechanism and its clinical implications in conditions such as ischemic stroke, head trauma, glaucoma, and age-associated memory impairment. Citicoline's anti-inflammatory prowess is rooted in its ability to stabilize cellular membranes, thereby curbing the excessive release of glutamate-a pro-inflammatory neurotransmitter. Moreover, it actively diminishes free radicals and inflammatory cytokines productions, which could otherwise harm neurons and incite neuroinflammation. It also exhibits the potential to modulate microglia activity, the brain's resident immune cells, and hinder the activation of NF-κB, a transcription factor governing inflammatory genes. Clinical trials have subjected citicoline to rigorous scrutiny in patients grappling with acute ischemic stroke, head trauma, glaucoma, and age-related memory impairment. While findings from these trials are mixed, numerous studies suggest that citicoline could confer improvements in neurological function, disability reduction, expedited recovery, and cognitive decline prevention within these cohorts. Additionally, citicoline boasts a favorable safety profile and high tolerability. In summary, citicoline stands as a promising agent, wielding both neuroprotective and anti-inflammatory potential across a spectrum of neurological conditions. However, further research is imperative to delineate the optimal dosage, treatment duration, and underlying mechanisms. Moreover, identifying specific patient subgroups most likely to reap the benefits of citicoline as a new therapy remains a critical avenue for exploration.

Intercellular Adhesion Molecule 1 (ICAM-1): An Inflammatory Regulator with Potential Implications in Ferroptosis and Parkinson's Disease

Intercellular adhesion molecule 1 (ICAM-1/CD54), a transmembrane glycoprotein, has been considered as one of the most important adhesion molecules during leukocyte recruitment. It is encoded by the ICAM1 gene and plays a central role in inflammation. Its crucial role in many inflammatory diseases such as ulcerative colitis and rheumatoid arthritis are well established. Given that neuroinflammation, underscored by microglial activation, is a key element in neurodegenerative diseases such as Parkinson's disease (PD), we investigated whether ICAM-1 has a role in this progressive neurological condition and, if so, to elucidate the underpinning mechanisms. Specifically, we were interested in the potential interaction between ICAM-1, glial cells, and ferroptosis, an iron-dependent form of cell death that has recently been implicated in PD. We conclude that there exist direct and indirect (via glial cells and T cells) influences of ICAM-1 on ferroptosis and that further elucidation of these interactions can suggest novel intervention for this devastating disease.

Clinical, mechanistic, biomarker, and therapeutic advances in GBA1-associated Parkinson's disease

Parkinson's disease (PD) is the second most common neurodegenerative disease. The development of PD is closely linked to genetic and environmental factors, with GBA1 variants being the most common genetic risk. Mutations in the GBA1 gene lead to reduced activity of the coded enzyme, glucocerebrosidase, which mediates the development of PD by affecting lipid metabolism (especially sphingolipids), lysosomal autophagy, endoplasmic reticulum, as well as mitochondrial and other cellular functions. Clinically, PD with GBA1 mutations (GBA1-PD) is characterized by particular features regarding the progression of symptom severity. On the therapeutic side, the discovery of the relationship between GBA1 variants and PD offers an opportunity for targeted therapeutic interventions. In this review, we explore the genotypic and phenotypic correlations, etiologic mechanisms, biomarkers, and therapeutic approaches of GBA1-PD and summarize the current state of research and its challenges.

Neurotoxicity, Neuroprotection, In Vitro MAOA/MAOB Inhibitory Activity Assessment, Molecular Docking, and Permeability Assay Studies of Newly Synthesized Hydrazones Containing a Pyrrole Ring

Neurodegenerative diseases such as Parkinson's and Alzheimer's continue to be some of the most significant challenges in modern medicine. Recent research related to the molecular mechanisms of parkinsonism has opened up new approaches to antiparkinsonian therapy. In response to this, we present the evaluation of the potential neuroprotective and MAOA/MAOB inhibitory effects of newly synthesized hydrazones, containing a pyrrole moiety in the carboxyl fragment of the structure. The substances were studied on different brain subcellular fractions, including rat brain synaptosomes, mitochondria, and microsomes. The single application of 50 µM of each compound to the subcellular fractions showed that all substances exhibit a weak neurotoxic effect, with 7b, 7d, and 8d being the least neurotoxic representatives. The corresponding neuroprotective and antioxidant effects were also evaluated in different injury models on subcellular fractions, single out 7b, 7d, and 8d as the most prominent derivatives. A 1 µM concentration of each molecule from the series was also studied for potential hMAOA/hMAOB inhibitory effects. The results revealed a lack of hMAOA activity for all evaluated structures and the appearance of hMAOB effects, with compounds 7b, 7d, and 8d showing effects similar to those of selegiline. The best hMAOB selectivity index (>204) was determined for 7d and 8d, distinguishing these two representatives as the most promising molecules for further studies as potential selective MAOB inhibitors. The performed molecular docking simulations defined the appearance of selective MAOB inhibitory effects based on the interaction of the tested molecules with Tyr398, which is one of the components of the aromatic cage of MAOB and participated in π-π stabilization with the aromatic pyrrole ring. The preliminary PAMPA testing indicated that in relation to the blood-brain barrier (BBB) permeability, the tested pyrrole-based hydrazones may be considered as high permeable, except for 8a and 8e, which were established to be permeable in the medium range with -logP of 5.268 and 5.714, respectively, compared to the applied references.

Activation of bitter taste receptors (TAS2R) protects against rotenone-induced neurotoxicity: Could ghrelin have a role?

AIMS

Bitter taste receptors (TAS2Rs) and their downstream signaling pathways are expressed not only in the oral tissues but also in extraoral tissues. Emerging data has demonstrated the beneficial effect of ghrelin in neurodegenerative diseases. Gaining more insight into the interaction between TAS2Rs and gut hormones may expand their therapeutic applications. Herein, we aimed to assess the possible effect of TAS2R activation by denatonium benzoate (DB) in modulating functional and neurobiochemical alterations in a model of Parkinson's disease (PD).

MAIN METHODS

PD model was induced by daily injection of rotenone (2 mg/kg). Rats received DB (5 mg/kg), atenolol (10 mg/kg), or both concomitantly with rotenone, daily for 28 days. Evaluation of the motor abnormalities and histological examination of brain tissues were conducted. In addition, striatal dopamine contents, immunohistochemical expression of tyrosine hydroxylase, plasma ghrelin level, and biochemical analysis of markers of inflammation and oxidative stress were assessed.

KEY FINDINGS

Treatment with DB increased serum levels of ghrelin and striatal dopamine contents with consequent amelioration of oxidative stress and attenuation of inflammatory cytokines. Moreover, DB treatment significantly ameliorated motor disturbance and histological abnormalities compared to untreated rats. Atenolol inhibited ghrelin release and abolished the positive effect of DB suggesting the involvement of ghrelin on such effects.

SIGNIFICANCE

The current study suggests that TAS2Rs agonists are promising candidates for ameliorating rotenone-induced PD pathology in rats, an action that could be linked to the enhancement of ghrelin release with consequent antioxidant and anti-inflammatory activities.

The humoral immune landscape in Parkinson's disease: Unraveling antibody and B cell changes

Parkinson's disease (PD) is a complex neurodegenerative disorder characterized by the accumulation of α-synuclein (α-syn) in the brain and progressive loss of dopaminergic neurons in the substantia nigra (SN) region of the brain. Although the role of neuroinflammation and cellular immunity in PD has been extensively studied, the involvement of humoral immunity mediated by antibodies and B cells has received less attention. This article provides a comprehensive review of the current understanding of humoral immunity in PD. Here, we discuss alterations in B cells in PD, including changes in their number and phenotype. Evidence mostly indicates a decrease in the quantity of B cells in PD, accompanied by a shift in the population from naïve to memory cells. Furthermore, the existence of autoantibodies that target several antigens in PD has been investigated (i.e., anti-α-syn autoantibodies, anti-glial-derived antigen antibodies, anti-Tau antibodies, antineuromelanin antibodies, and antibodies against the renin-angiotensin system). Several autoantibodies are generated in PD, which may either provide protection or have harmful effects on disease progression. Furthermore, we have reviewed studies focusing on the utilization of antibodies as a potential treatment for PD, both in animal and clinical trials. This review sheds light on the intricate interplay between antibodies and the pathological processes in PD, including complement system activation.

Navitoclax safety, tolerability, and effect on biomarkers of senescence and neurodegeneration in aged nonhuman primates

Alzheimer's disease (AD) is the most common global dementia and is universally fatal. Most late-stage AD disease-modifying therapies are intravenous and target amyloid beta (Aβ), with only modest effects on disease progression: there remains a high unmet need for convenient, safe, and effective therapeutics. Senescent cells (SC) and the senescence-associated secretory phenotype (SASP) drive AD pathology and increase with AD severity. Preclinical senolytic studies have shown improvements in neuroinflammation, tau, Aβ, and CNS damage; most were conducted in transgenic rodent models with uncertain human translational relevance. In this study, aged cynomolgus monkeys had significant elevation of biomarkers of senescence, SASP, and neurological damage. Intermittent treatment with the senolytic navitoclax induced modest reversible thrombocytopenia; no serious drug-related toxicity was noted. Navitoclax reduced several senescence and SASP biomarkers, with CSF concentrations sufficient for senolysis. Finally, navitoclax reduced TSPO-PET frontal cortex binding and showed trends of improvement in CSF biomarkers of neuroinflammation, neuronal damage, and synaptic dysfunction. Overall, navitoclax administration was safe and well tolerated in aged monkeys, inducing trends of biomarker changes relevant to human neurodegenerative disease.

Autism-associated CHD8 controls reactive gliosis and neuroinflammation via remodeling chromatin in astrocytes

Reactive changes of glial cells during neuroinflammation impact brain disorders and disease progression. Elucidating the mechanisms that control reactive gliosis may help us to understand brain pathophysiology and improve outcomes. Here, we report that adult ablation of autism spectrum disorder (ASD)-associated CHD8 in astrocytes attenuates reactive gliosis via remodeling chromatin accessibility, changing gene expression. Conditional Chd8 deletion in astrocytes, but not microglia, suppresses reactive gliosis by impeding astrocyte proliferation and morphological elaboration. Astrocyte Chd8 ablation alleviates lipopolysaccharide-induced neuroinflammation and septic-associated hypothermia in mice. Astrocytic CHD8 plays an important role in neuroinflammation by altering the chromatin landscape, regulating metabolic and lipid-associated pathways, and astrocyte-microglia crosstalk. Moreover, we show that reactive gliosis can be directly mitigated in vivo using an adeno-associated virus (AAV)-mediated Chd8 gene editing strategy. These findings uncover a role of ASD-associated CHD8 in the adult brain, which may warrant future exploration of targeting chromatin remodelers in reactive gliosis and neuroinflammation in injury and neurological diseases.

Chronic Cocaine Use and Parkinson's Disease: An Interpretative Model

Over the years, the growing "epidemic" spread of cocaine use represents a crucial public health and social problem worldwide. According to the 2023 World Drug Report, 0.4% of the world's population aged 15 to 64 report using cocaine; this number corresponds to approximately 24.6 million cocaine users worldwide and approximately 1 million subjects with cocaine use disorder (CUD). While we specifically know the short-term side effects induced by cocaine, unfortunately, we currently do not have exhaustive information about the medium/long-term side effects of the substance on the body. The scientific literature progressively highlights that the chronic use of cocaine is related to an increase in cardio- and cerebrovascular risk and probably to a greater incidence of psychomotor symptoms and neurodegenerative processes. Several studies have highlighted an increased risk of antipsychotic-induced extrapyramidal symptoms (EPSs) in patients with psychotic spectrum disorders comorbid with psychostimulant abuse. EPSs include movement dysfunction such as dystonia, akathisia, tardive dyskinesia, and characteristic symptoms of Parkinsonism such as rigidity, bradykinesia, and tremor. In the present paper, we propose a model of interpretation of the neurobiological mechanisms underlying the hypothesized increased vulnerability in chronic cocaine abusers to neurodegenerative disorders with psychomotor symptoms. Specifically, we supposed that the chronic administration of cocaine produces significant neurobiological changes, causing a complex dysregulation of various neurotransmitter systems, mainly affecting subcortical structures and the dopaminergic pathways. We believe that a better understanding of these cellular and molecular mechanisms involved in cocaine-induced neuropsychotoxicity may have helpful clinical implications and provide targets for therapeutic intervention.

MicroRNAs Modulating Neuroinflammation in Parkinson's disease

Parkinson's disease (PD) is one of the most frequent age-associated neurodegenerative disorder. Presence of α-synuclein-containing aggregates in the substantia nigra pars compacta (SNpc) and loss of dopaminergic (DA) neurons are among the characteristic of PD. One of the hallmarks of PD pathophysiology is chronic neuroinflammation. Activation of glial cells and elevated levels of pro-inflammatory factors are confirmed as frequent features of the PD brain. Chronic secretion of pro-inflammatory cytokines by activated astrocytes and microglia exacerbates DA neuron degeneration in the SNpc. MicroRNAs (miRNAs) are among endogenous non-coding small RNA with the ability to perform post-transcriptional regulation in target genes. In that regard, the capability of miRNAs for modulating inflammatory signaling is the center of attention in many investigations. MiRNAs could enhance or limit inflammatory signaling, exacerbating or ameliorating the pathological consequences of extreme neuroinflammation. This review summarizes the importance of inflammation in the pathophysiology of PD. Besides, we discuss the role of miRNAs in promoting or protecting neural cell injury in the PD model by controlling the inflammatory pathway. Modifying the neuroinflammation by miRNAs could be considered a primary therapeutic strategy for PD.

Effect of Capsaicin on 3-NP-Induced Neurotoxicity: A Pre-Clinical Study

The study objectives are to investigate the ability of capsaicin to revert the toxic effects in glutamate and lipopolysaccharide (LPS)-induced neurotoxicity in Neuro2a (N2a) cells as well as thwarting cognitive impairments, mitochondrial deficits, and oxidative insults induced by 3-nitropropanoic acid (3-NP) in a rodent model of Huntington's disease. In-vitro study with N2a cells was performed through MTT and LDH assay and their biochemical examinations were also performed. 3-NP-administered mice (n = 6) were treated with capsaicin (5, 10, and 20 mg/kg) through the per-oral (p.o.) route for 7 consecutive days. Physiological and behavioral studies were performed in drug-treated mice. After behavioral studies, biochemical parameters were performed for cytokines levels, various oxidative stress parameters, and mitochondrial enzyme complex activities with mitochondrial permeability. N2a cells treated with capsaicin demonstrated neuroprotective effects and reduced neurotoxicity. Based on experimental observation, in an in-vitro study, the effective dose of CAP was 50 µM. Moreover, a 100 µM dose of capsaicin had toxic effects on neuronal cells (N2a cells). On the other hand, the effective dose of 3-NP was 20 mg/kg, (p.o.) in animals (in-vivo). All tested doses of capsaicin upturned the cognitive impairment and motor in-coordination effects induced by 3-NP. 3-NP-injected mice demonstrated substantially increased pro-inflammatory cytokine concentrations, defective mitochondrial complex activity, and augmented oxidative insult. However, capsaicin at different doses reduced oxidative damage and cytokines levels and improved mitochondrial complex activity along with mitochondrial permeability. Furthermore, capsaicin (10 and 20 mg/kg) improved the TNF-α concentration. These findings suggested because of the anti-inflammatory and antioxidant effect, capsaicin can be considered a novel treatment for the management of neurodegenerative disorders by reverting the antioxidant enzyme activity, pro-inflammatory cytokines concentration, and mitochondrial functions.

Immunomodulator-Derived Nanoparticles Induce Neuroprotection and Regulatory T Cell Action to Alleviate Parkinsonism

Post-translational modification, mitochondrial abruptions, neuroinflammation, and α-synuclein (α-Syn) aggregation are considered as major causes of Parkinson's disease (PD) pathogenesis. The recent literature highlights neuroimmune cross talk and the negative role of immune effector T (Teff) and positive regulation by regulatory T (Treg) cells in PD treatment. Herein, a strategy to endow Treg action paves the path for development of PD treatment. Thus, we explored the neuroprotective efficiency of the immunomodulator and PP2A (protein phosphatase 2) activator, FTY720 nanoparticles in in vivo experimental PD models. Repurposing of FTY720 for PD is known due to its protective effect by reducing PD and its camouflaged role in endowing EZH2-mediated epigenetic regulation of PD. EZH2-FOXP3 interaction is necessary for the neuroprotective Treg cell activity. Therefore, we synthesized FTY720 nanoparticles to improve FTY720 protective efficacy in an in vivo PD model to explore the PP2A mediated signaling. We confirmed the formation of FTY720NPs, and the results of the behavioral and protein expression study showed the significant neuroprotective efficiency of our nanoformulations. In the exploration of neuroprotective mechanism, several lines of evidence confirmed FTY720NPs mediated induction of PP2A/EZH2/FOXP3 signaling in the induction of Treg cells effect in in vivo PD treatment. In summary, our nanoformulations have novel potential to alleviate PD by inducing PP2A-induced epigenetic regulation-mediated neuroimmunomodulation at the clinical setup.

TMEM106B Knockdown Exhibits a Neuroprotective Effect in Parkinson's Disease via Decreasing Inflammation and Iron Deposition

Parkinson's disease (PD) is closely related to iron accumulation and inflammation. Emerging evidence indicates that TMEM106B plays an essential role in PD. But whether TMEM106B could act on neuroinflammation and iron metabolism in PD has not yet been investigated. The aim of this study was to investigate the pathological mechanisms of inflammation and iron metabolism of TMEM106B in PD. 1-methyl-4-phenylpyridinium (MPP+)- and 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine (MPTP)-induced SH-SY5Y cells and mice were treated with LV-shTMEM106B and AAV-shTMEM106B to construct PD cellular and mouse models. Pole tests and open-field test (OFT) were performed to evaluate the locomotion of the mice. Immunohistochemistry and iron staining were used to detect TH expression and iron deposition in the SN. Iron staining was used to measure the levels of iron. Western blotting was used to detect the expression of inflammatory factors (tumor necrosis factor-α (TNF-α), interleukin-6 (IL-6)), NOD-like receptor protein 3 (NLRP3) inflammasome, divalent metal transporter 1 (DMT1), and Ferroportin1 (FPN1)). Knockdown of TMEM106B improved motor ability and rescued dopaminergic (DA) neuron loss. TMEM106B knockdown attenuated the increases of TNF-α, IL-6, NLRP3 inflammasome, and DMT1 expression in the MPP+ and MPTP-induced PD models. Furthermore, TMEM106B knockdown also increases the expression of FPN1. This study provides the first evidence that knockdown of TMEM106B prevents dopaminergic neurodegeneration by modulating neuroinflammation and iron metabolism.

Genus Sambucus: Exploring Its Potential as a Functional Food Ingredient with Neuroprotective Properties Mediated by Antioxidant and Anti-Inflammatory Mechanisms

The genus Sambucus, mainly Sambucus nigra, has emerged as a valuable source of bioactive compounds with potential neuroprotective properties. This review explores the antioxidant, anti-inflammatory, and neuroregenerative effects of Sambucus-derived compounds and their implications for brain health and cognitive function. In vitro studies have demonstrated the ability of Sambucus extracts to mitigate oxidative stress, modulate inflammatory responses, and promote neural stem cell proliferation and differentiation. In vivo studies using animal models of neurodegenerative diseases, such as Alzheimer's and Parkinson's, have shown that Sambucus compounds can improve cognitive function, motor performance, and neuronal survival while attenuating neuroinflammation and oxidative damage. The neuroprotective effects of Sambucus are primarily attributed to its rich content of polyphenols, particularly anthocyanins, which exert their benefits through multiple mechanisms, including the modulation of signaling pathways involved in inflammation, apoptosis, mitochondrial function, and oxidative stress. Furthermore, the potential of Sambucus as a functional food ingredient is discussed, highlighting its application in various food products and the challenges associated with the stability and bioavailability of its bioactive compounds. This review provides a comprehensive overview of the current state of research on the neuroprotective potential of Sambucus and its derivatives, offering valuable insights for the development of dietary strategies to promote brain health and prevent age-related cognitive decline.

Delivery of CDNF by AAV-mediated gene transfer protects dopamine neurons and regulates ER stress and inflammation in an acute MPTP mouse model of Parkinson's disease

Cerebral dopamine neurotrophic factor (CDNF) and its close structural relative, mesencephalic astrocyte-derived neurotrophic factor (MANF), are proteins with neurotrophic properties. CDNF protects and restores the function of dopamine (DA) neurons in rodent and non-human primate (NHP) toxin models of Parkinson's disease (PD) and therefore shows promise as a drug candidate for disease-modifying treatment of PD. Moreover, CDNF was found to be safe and to have some therapeutic effects on PD patients in phase 1/2 clinical trials. However, the mechanism underlying the neurotrophic activity of CDNF is unknown. In this study, we delivered human CDNF (hCDNF) to the brain using an adeno-associated viral (AAV) vector and demonstrated the neurotrophic effect of AAV-hCDNF in an acute 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine (MPTP) mouse model of PD. AAV-hCDNF resulted in the expression of hCDNF in the striatum (STR) and substantia nigra (SN), and no toxic effects on the nigrostriatal pathway were observed. Intrastriatal injection of AAV-hCDNF reduced motor impairment and partially alleviated gait dysfunction in the acute MPTP mouse model. In addition, gene therapy with AAV-hCDNF had significant neuroprotective effects on the nigrostriatal pathway and decreased the levels of interleukin 1beta (IL-1β) and complement 3 (C3) in glial cells in the acute MPTP mouse model. Moreover, AAV-hCDNF reduced C/EBP homologous protein (CHOP) and glucose regulatory protein 78 (GRP78) expression in astroglia. These results suggest that the neuroprotective effects of CDNF may be mediated at least in part through the regulation of neuroinflammation and the UPR pathway in a mouse MPTP model of PD in vivo.

Postbiotics as Molecules Targeting Cellular Events of Aging Brain-The Role in Pathogenesis, Prophylaxis and Treatment of Neurodegenerative Diseases

Aging is the most prominent risk factor for neurodegeneration occurrence. The most common neurodegenerative diseases (NDs), Alzheimer's (AD) and Parkinson's (PD) diseases, are characterized by the incidence of proteinopathy, abnormal activation of glial cells, oxidative stress, neuroinflammation, impaired autophagy and cellular senescence excessive for the patient's age. Moreover, mitochondrial disfunction, epigenetic alterations and neurogenesis inhibition, together with increased blood-brain barrier permeability and gut dysbiosis, have been linked to ND pathogenesis. Since NDs still lack curative treatment, recent research has sought therapeutic options in restoring gut microbiota and supplementing probiotic bacteria-derived metabolites with beneficial action to the host-so called postbiotics. The current review focuses on literature explaining cellular mechanisms involved in ND pathogenesis and research addressing the impact that postbiotics as a whole mixture and particular metabolites, such as short-chain fatty acids (SCFAs), lactate, polyamines, polyphenols, tryptophan metabolites, exopolysaccharides and bacterial extracellular vesicles, have on the ageing-associated processes underlying ND occurrence. The review also discusses the issue of implementing postbiotics into ND prophylaxis and therapy, depicting them as compounds addressing senescence-triggered dysfunctions that are worth translating from bench to pharmaceutical market in response to "silver consumers" demands.

Emerging Role of Long Noncoding RNAs in Regulating Inflammasome-Mediated Neurodegeneration in Parkinson's Disease

Parkinson's disease (PD) is one of the complex neurodegenerative disorders, primarily characterized by motor deficits, including bradykinesia, tremor, rigidity, and postural instability. The underlying pathophysiology involves the progressive loss of dopaminergic neurons within the substantia nigra pars compacta, leading to dopamine depletion in the basal ganglia circuitry. While motor symptoms are hallmark features of PD, emerging research highlights a wide range of non-motor symptoms, including cognitive impairments, mood disturbances, and autonomic dysfunctions. Inflammasome activation is pivotal in inducing neuroinflammation and promoting disease onset, progression, and severity of PD. Several studies have shown that long noncoding RNAs (lncRNAs) modulate inflammasomes in the pathogenesis of neurodegenerative diseases. Dysregulation of lncRNAs is linked to aberrant gene expression and cellular processes in neurodegeneration, causing the activation of inflammasomes that contribute to neuroinflammation and neurodegeneration. Inflammasomes are cytosolic proteins that form complexes upon activation, inducing inflammation and neuronal cell death. This review explores the significance of lncRNAs in regulating inflammasomes in PD, primarily focusing on specific lncRNAs such as nuclear paraspeckle assembly transcript 1 (NEATNEAT1), X-inactive specific transcript (XIST), growth arrest-specific 5 (GAS5), and HOX transcript antisense RNA (HOTAIR), which have been shown to activate or inhibit the NLRP3 inflammasome and induce the release of proinflammatory cytokines. Moreover, some lncRNAs mediate inflammasome activation through miRNA interactions. Understanding the roles of lncRNAs in inflammasome regulation provides new therapeutic targets for controlling neuroinflammation and reducing the progression of neurodegeneration. Identifying lncRNA-mediated regulatory pathways paves the way for novel therapies in the battle against these devastating neurodegenerative disorders.

Neuroinflammation is dependent on sex and ovarian hormone presence following acute woodsmoke exposure

Woodsmoke (WS) exposure is associated with significant health-related sequelae. Different populations can potentially exhibit varying susceptibility, based on endocrine phenotypes, to WS and investigating neurological impacts following inhaled WS is a growing area of research. In this study, a whole-body inhalation chamber was used to expose both male and female C57BL/6 mice (n = 8 per group) to either control filtered air (FA) or acute WS (0.861 ± 0.210 mg/m3) for 4 h/d for 2 days. Neuroinflammatory and lipid-based biological markers were then assessed. In a second set of studies, female mice were divided into two groups: one group was ovariectomized (OVX) to simulate an ovarian hormone-deficient state (surgical menopause), and the other underwent Sham surgery as controls, to mechanistically assess the impact of ovarian hormone presence on neuroinflammation following FA and acute WS exposure to simulate an acute wildfire episode. There was a statistically significant impact of sex (P ≤ 0.05) and statistically significant interactions between sex and treatment in IL-1β, CXCL-1, TGF-β, and IL-6 brain relative gene expression. Hippocampal and cortex genes also exhibited significant changes in acute WS-exposed Sham and OVX mice, particularly in TGF-β (hippocampus) and CCL-2 and CXCL-1 (cortex). Cortex GFAP optical density (OD) showed a notable elevation in male mice exposed to acute WS, compared to the control FA. Sham and OVX females demonstrated differential GFAP expression, depending on brain region. Overall, targeted lipidomics in phosphatidylcholine (PC) and phosphatidylethanolamine (PE) serum and brain lipids demonstrated more significant changes between control FA and acute WS exposure in female mice, compared to males. In summary, male and female mice show distinct neuroinflammatory markers in response to acute WS exposure. Furthermore, ovarian hormone deficiency may impact the neuroinflammatory response following an acute WS event.

Innovative approaches to Alzheimer's therapy: Harnessing the power of heterocycles, oxidative stress management, and nanomaterial drug delivery system

Alzheimer's disease (AD) presents a complex pathology involving amyloidogenic proteolysis, neuroinflammation, mitochondrial dysfunction, and cholinergic deficits. Oxidative stress exacerbates AD progression through pathways like macromolecular peroxidation, mitochondrial dysfunction, and metal ion redox potential alteration linked to amyloid-beta (Aβ). Despite limited approved medications, heterocyclic compounds have emerged as promising candidates in AD drug discovery. This review highlights recent advancements in synthetic heterocyclic compounds targeting oxidative stress, mitochondrial dysfunction, and neuroinflammation in AD. Additionally, it explores the potential of nanomaterial-based drug delivery systems to overcome challenges in AD treatment. Nanoparticles with heterocyclic scaffolds, like polysorbate 80-coated PLGA and Resveratrol-loaded nano-selenium, show improved brain transport and efficacy. Micellar CAPE and Melatonin-loaded nano-capsules exhibit enhanced antioxidant properties, while a tetra hydroacridine derivative (CHDA) combined with nano-radiogold particles demonstrates promising acetylcholinesterase inhibition without toxicity. This comprehensive review underscores the potential of nanotechnology-driven drug delivery for optimizing the therapeutic outcomes of novel synthetic heterocyclic compounds in AD management. Furthermore, the inclusion of various promising heterocyclic compounds with detailed ADMET (Absorption, Distribution, Metabolism, Excretion, and Toxicity) data provides valuable insights for planning the development of novel drug delivery treatments for AD.

Therapeutic Targeting of Krüppel-Like Factor 4 and Its Pharmacological Potential in Parkinson's Disease: a Comprehensive Review

Krüppel-like factor 4 (KLF4), a zinc finger transcription factor, is found in different human tissues and shows diverse regulatory activities in a cell-dependent manner. In the brain, KLF4 controls various neurophysiological and neuropathological processes, and its contribution to various neurological diseases has been widely reported. Parkinson's disease (PD) is an age-related neurodegenerative disease that might have a connection with KLF4. In this review, we discussed the potential implication of KLF4 in fundamental molecular mechanisms of PD, including aberrant proteostasis, neuroinflammation, apoptosis, oxidative stress, and iron overload. The evidence collected herein sheds new light on KLF4-mediated pathways, which manipulation appears to be a promising therapeutic target for PD management. However, there is a gap in the knowledge on this topic, and extended research is required to understand the translational value of the KLF4-oriented therapeutical approach in PD.

Indoleamine 2,3-dioxygenase (IDO1) - Can dendritic cells and monocytes expressing this moonlight enzyme change the phase of Parkinson's Disease?

Parkinson's Disease (PD) is the second most common neurodegenerative disease where central and peripheral immune dysfunctions have been pointed out as a critical component of susceptibility and progression of this disease. Dendritic cells (DCs) and monocytes are key players in promoting immune response regulation and can induce the enzyme indoleamine 2,3-dioxygenase 1 (IDO1) under pro-inflammatory environments. This enzyme with catalytic and signaling activity supports the axis IDO1-KYN-aryl hydrocarbon receptor (AhR), promoting disease-specific immunomodulatory effects. IDO1 is a rate-limiting enzyme of the kynurenine pathway (KP) that begins tryptophan (Trp) catabolism across this pathway. The immune functions of the pathway, which are extensively described in cancer, have been forgotten so far in neurodegenerative diseases, where a chronic inflammatory environment underlines the progression of the disease. Despite dysfunctions of KP have been described in PD, these are mainly associated with neurotoxic functions. With this review, we aim to focus on the immune properties of IDO1+DCs and IDO1+monocytes as a possible strategy to balance the pro-inflammatory profile described in PD. We also highlight the importance of exploring the role of dopaminergic therapeutics in IDO1 modulation to possibly optimize current PD therapeutic strategies.

Orexin B protects dopaminergic neurons from 1-Methyl-4-phenyl-1,2,3,6-tetrahydropyridine-induced neurotoxicity associated with reduced extracellular signal-regulated kinase phosphorylation

BACKGROUND

The loss of dopaminergic (DA) neurons in the substantia nigra pars compacta (SNpc) is a major pathological hallmark of Parkinson's disease (PD). Orexin B (OXB) has been reported to promote the growth of DA neurons. However, the roles of OXB in the degeneration of DA neurons still remained not fully clear.

METHODS

An in vivo PD model was constructed by administrating 1-Methyl-4-phenyl-1,2,3,6-tetrahydropyridine (MPTP) in mice. Pole test was performed to investigate the motor function of mice and the number of DA neurons was detected by immunofluorescence (IF). A PD cell model was established by treating SH-SY5Y cells with 1-methyl-4-phenylpyridinium (MPP+). OXB was added to the culture medium 2 h after MPP + treatment. Microscopic analysis was carried out to investigate the function of OXB in the cell model of PD 24 h after MPP + challenge. RNA-Seq analysis of the PD cell model was performed to explore the possible mechanisms. Western blot was used to detect the phosphorylation levels of extracellular signal-regulated kinase (ERK).

RESULTS

OXB significantly decreased the DA neurons death caused by MPTP, alleviated MPP+-induced neurotoxicity in SH-SY5Y cells, and robustly enhanced the weight and motor ability of PD mice. Besides, RNA-Seq analysis demonstrated that the mitogen-activated protein kinase (MAPK) pathway was involved in the pathology of PD. Furthermore, MPP + led to increased levels of phosphorylation of ERK (p-ERK), OXB treatment significantly decreased the levels of p-ERK in MPP+-treated SH-SY5Y cells.

CONCLUSIONS

This study demonstrated that OXB exerts a neuroprotective role associated with reduced ERK phosphorylation in the PD model. This suggests that OXB may have therapeutic potential for treatment of PD.

Thioketal-Based Electrochemical Sensor Reveals Biphasic Effects of l-DOPA on Neuroinflammation

Neuroinflammation is linked closely to neurodegenerative diseases, with reactive oxygen species (ROS) exacerbating neuronal damage. Traditional electrochemical sensors show promise in targeting cellular ROS to understand their role in neuropathogenesis and assess therapies. Nevertheless, these sensors face challenges in mitigating the ROS oxidation overpotential. We herein introduce an ROS oxidation-independent nucleic acid sensor for in situ ROS analysis and therapeutic assessment. The sensor comprises ionizable and thioketal (TK)-based lipids with methylene blue-tagged nucleic acids on a glass carbon electrode. ROS exposure triggers cleavage within the sensor's thioketal moiety, detaching the nucleic acid from the electrode and yielding quantifiable results via square-wave voltammetry. Importantly, the sensor's low potential window minimizes interference, ensuring precise ROS measurements with high selectivity. Using this sensor, we unveil levodopa's dose-dependent biphasic effect on neuroinflammation: low doses alleviate oxidative stress, while high doses exacerbate it. The TK-based sensor offers a promising methodology for investigating neuroinflammation's pathogenesis and screening potential treatments, advancing neurodegenerative disease research.

How Biodegradable Polymers Can be Effective Drug Delivery Systems for Cannabinoids? Prospectives and Challenges

Cannabinoids are compounds found in and derived from the Cannabis plants that have become increasingly recognised as significant modulating factors of physiological mechanisms and inflammatory reactions of the organism, thus inevitably affecting maintenance of homeostasis. Medical Cannabis popularity has surged since its legal regulation growing around the world. Numerous promising discoveries bring more data on cannabinoids' pharmacological characteristics and therapeutic applications. Given the current surge in interest in the medical use of cannabinoids, there is an urgent need for an effective method of their administration. Surpassing low bioavailability, low water solubility, and instability became an important milestone in the advancement of cannabinoids in pharmaceutical applications. The numerous uses of cannabinoids in clinical practice remain restricted by limited administration alternatives, but there is hope when biodegradable polymers are taken into account. The primary objective of this review is to highlight the wide range of indications for which cannabinoids may be used, as well as the polymeric carriers that enhance their effectiveness. The current review described a wide range of therapeutic applications of cannabinoids, including pain management, neurological and sleep disorders, anxiety, and cancer treatment. The use of these compounds was further examined in the area of dermatology and cosmetology. Finally, with the use of biodegradable polymer-based drug delivery systems (DDSs), it was demonstrated that cannabinoids can be delivered specifically to the intended site while also improving the drug's physicochemical properties, emphasizing their utility. Nevertheless, additional clinical trials on novel cannabinoids' formulations are required, as their full spectrum therapeutical potential is yet to be unravelled.

Clarifying the association between Parkinson's disease and vitiligo: a population-based large-scale study

Objective

Our knowledge about the association between vitiligo and Parkinson's disease (PD) is sparse. We sought to investigate the bidirectional epidemiological association between vitiligo and PD.

Methods

A population-based study was conducted using Clalit Health Services (CHS) database (2002-2019) using both a cohort study and a case-control study design. Adjusted hazard ratio (HR) and odds ratio (OR) were calculated by multivariate Cox and logistic regressions, respectively.

Results

Overall, 20,851 vitiligo patients and 102,475 controls were included. The incidence of new-onset PD was 2.9 (95% CI, 2.1-4.1) and 4.3 (95% CI, 3.8-4.9) cases per 10,000 person-years among patients with vitiligo and controls, respectively. Patients with vitiligo had a significantly decreased risk of developing new-onset PD [adjusted HR, 0.62; 95% confidence interval (CI), 0.43-0.89, p = 0.009]. On the other hand, the likelihood of having vitiligo after a preexisting diagnosis of PD was not statistically different (adjusted OR, 0.80; 95% CI, 0.61-1.06; p = 0.117). Relative to the remaining patients with vitiligo, those with vitiligo and comorbid PD experienced an elevated risk of all-cause mortality (adjusted HR, 2.63; 95% CI, 1.82-3.80; p < 0.001) and higher prevalence of cardiometabolic comorbidities.

Conclusion

Vitiligo is associated with a lower risk of developing PD. The presence of comorbid PD predisposes patients with vitiligo to elevated mortality and cardiometabolic outcomes.

Non-HLA angiotensin-type-1 receptor autoantibodies mediate the long-term loss of grafted neurons in Parkinson's disease models

BACKGROUND

Clinical trials have provided evidence that transplants of dopaminergic precursors, which may be replaced by new in vitro stem cell sources, can integrate into the host tissue, and alleviate motor symptoms in Parkinson´s disease (PD). In some patients, deterioration of graft function occurred several months after observing a graft-derived functional improvement. Rejection of peripheral organs was initially related to HLA-specific antibodies. However, the role of non-HLA antibodies is now considered also relevant for rejection. Angiotensin-II type-1 receptor autoantibodies (AT1-AA) act as agonists of the AT1 receptors. AT1-AA are the non-HLA antibodies most widely associated with graft dysfunction or rejection after transplantation of different solid organs and hematopoietic stem cells. However, it is not known about the presence and possible functional effects of AT1-AA in dopaminergic grafts, and the effects of treatment with AT1 receptor blockers (ARBs) such as candesartan on graft survival.

METHODS

In a 6-hydroxydopamine PD rat model, we studied the short-term (10 days)- and long-term (3 months) effects of chronic treatment with the ARB candesartan on survival of grafted dopaminergic neurons and microglial graft infiltration, as well as the effects of dopaminergic denervation and grafting on serum and CSF AT1-AA levels. The expression of AT1 receptors in grafted neurons was determined by laser capture microdissection.

RESULTS

At the early period post-grafting, the number of grafted dopaminergic neurons that survived was not significantly different between treated and untreated hosts (i.e., control rats and rats treated with candesartan), probably because, just after grafting, other deleterious factors are predominant for dopaminergic cell death, such as mechanical trauma, lack of growth factors/nutrients and ischemia. However, several months post-grafting, we observed a significantly higher number of surviving dopaminergic neurons and a higher density of striatal dopaminergic terminals in the candesartan-treated group. For several months, grafted rats showed blood and cerebrospinal fluid levels of AT1-AA higher than normal controls, and also higher AT1-AA levels than non-grafted parkinsonian rats.

CONCLUSIONS

The results suggest the use of ARBs such as candesartan in PD patients, particularly before and after dopaminergic grafts, and the need to monitor AT1-AA levels in PD patients, particularly in those candidates for dopaminergic grafting.

Novel Findings on CCR1 Receptor in CNS Disorders: A Pathogenic Marker Useful in Controlling Neuroimmune and Neuroinflammatory Mechanisms in Parkinson's Disease

Parkinson's disease (PD) is recognized as the second most common neurodegenerative disease worldwide. Even if PD etiopathogenesis is not yet fully understood, in recent years, it has been advanced that a chronic state of inflammation could play a decisive role in the development of this pathology, establishing the close link between PD and neuroinflammation. In the broad panorama of inflammation and its several signaling pathways, the C-C chemokine receptor type 1 (CCR1) could play a key pathogenic role in PD progression, and could constitute a valuable target for the development of innovative anti-PD therapies. In this study, we probed the neuroprotective properties of the CCR1 antagonist BX471 compound in a mouse model of MPTP-induced nigrostriatal degeneration. BX471 treatments were performed intraperitoneally at a dose of 3 mg/kg, 10 mg/kg, and 30 mg/kg, starting 24 h after the last injection of MPTP and continuing for 7 days. From our data, BX471 treatment strongly blocked CCR1 and, as a result, decreased PD features, also reducing the neuroinflammatory state by regulating glial activation, NF-κB pathway, proinflammatory enzymes, and cytokines overexpression. Moreover, we showed that BX471's antagonistic action on CCR1 reduced the infiltration of immune cells, including mast cells and lymphocyte T activation. In addition, biochemical analyses carried out on serum revealed a considerable increase in circulating levels of CCR1 following MPTP-induced PD. In light of these findings, CCR1 could represent a useful pathological marker of PD, and its targeting could be a worthy candidate for the future development of new immunotherapies against PD.

An Update on the Potential of Tangeretin in the Management of Neuroinflammation-Mediated Neurodegenerative Disorders

Neuroinflammation is the major cause of neurodegenerative disorders such as Alzheimer's and Parkinson's disease. Currently available drugs present relatively low efficacy and are not capable of modifying the course of the disease or delaying its progression. Identifying well-tolerated and brain-penetrant agents of plant origin could fulfil the pressing need for novel treatment techniques for neuroinflammation. Attention has been drawn to a large family of flavonoids in citrus fruits, which may function as strong nutraceuticals in slowing down the development and progression of neuroinflammation. This review is aimed at elucidating and summarizing the effects of the flavonoid tangeretin (TAN) in the management of neuroinflammation-mediated neurodegenerative disorders. A literature survey was performed using various resources, including ScienceDirect, PubMed, Google Scholar, Springer, and Web of Science. The data revealed that TAN exhibited immense neuroprotective effects in addition to its anti-oxidant, anti-diabetic, and peroxisome proliferator-activated receptor-γ agonistic effects. The effects of TAN are mainly mediated through the inhibition of oxidative and inflammatory pathways via regulating multiple signaling pathways, including c-Jun N-terminal kinase, phosphoinositide 3-kinase, mitogen-activated protein kinase, nuclear factor erythroid-2-related factor 2, extracellular-signal-regulated kinase, and CRE-dependent transcription. In conclusion, the citrus flavonoid TAN has the potential to prevent neuronal death mediated by neuroinflammatory pathways and can be developed as an auxiliary therapeutic agent in the management of neurodegenerative disorders.

Neuroinflammation in Neurodegenerative Disorders: Current Knowledge and Therapeutic Implications

Neurodegenerative disorders (NDs) have become increasingly common during the past three decades. Approximately 15% of the total population of the world is affected by some form of NDs, resulting in physical and cognitive disability. The most common NDs include Alzheimer's disease, Parkinson's disease, amyotrophic lateral sclerosis, and Huntington's disease. Although NDs are caused by a complex interaction of genetic, environmental, and lifestyle variables, neuroinflammation is known to be associated with all NDs, often leading to permanent damage to neurons of the central nervous system. Furthermore, numerous emerging pieces of evidence have demonstrated that inflammation not only supports the progression of NDs but can also serve as an initiator. Hence, various medicines capable of preventing or reducing neuroinflammation have been investigated as ND treatments. While anti-inflammatory medicine has shown promising benefits in several preclinical models, clinical outcomes are often questionable. In this review, we discuss various NDs with their current treatment strategies, the role of neuroinflammation in the pathophysiology of NDs, and the use of anti-inflammatory agents as a potential therapeutic option.

Neuroimmune Connectomes in the Gut and Their Implications in Parkinson's Disease

The gastrointestinal tract is the largest immune organ and it receives dense innervation from intrinsic (enteric) and extrinsic (sympathetic, parasympathetic, and somatosensory) neurons. The immune and neural systems of the gut communicate with each other and their interactions shape gut defensive mechanisms and neural-controlled gut functions such as motility and secretion. Changes in neuroimmune interactions play central roles in the pathogenesis of diseases such as Parkinson's disease (PD), which is a multicentric disorder that is heterogeneous in its manifestation and pathogenesis. Non-motor and premotor symptoms of PD are common in the gastrointestinal tract and the gut is considered a potential initiation site for PD in some cases. How the enteric nervous system and neuroimmune signaling contribute to PD disease progression is an emerging area of interest. This review focuses on intestinal neuroimmune loops such as the neuroepithelial unit, enteric glial cells and their immunomodulatory effects, anti-inflammatory cholinergic signaling and the relationship between myenteric neurons and muscularis macrophages, and the role of α-synuclein in gut immunity. Special consideration is given to the discussion of intestinal neuroimmune connectomes during PD and their possible implications for various aspects of the disease.

Causal role of immune cells on risk of Parkinson's disease: a Mendelian randomization study

Background

Previous observational studies have suggested a correlation between immune cells and Parkinson's disease (PD), yet specific investigations into the causal relationship between the two remain limited. This study aims to explore this potential causal relationship.

Methods

We utilized genome-wide association study (GWAS) data on immune cells and Parkinson's Disease, conducting a two-sample Mendelian randomization (MR) analysis using single nucleotide polymorphisms (SNPs). To estimate causality, we employed inverse variance weighting (IVW), MR-Egger, and weighted median (WM) methods. For sensitivity analysis, we used Cochran's Q-test, MR-Egger intercept, leave-one-out analysis, and funnel plots.

Results

After false discovery rate (FDR) correction, the effects of PD on immune cells, and vice versa, were not statistically significant. These include CX3CR1 on CD14+ CD16-monocyte (OR = 0.91, 95% CI = 0.86-0.96, p = 0.0003 PFDR = 0.152), CD62L-CD86+ myeloid DC AC (OR = 0.93, 95% CI = 0.89-0.97, p = 0.0005, PFDR = 0.152),CD11b on Mo (OR = 1.08, 95% CI = 1.03-1.13, p = 0.001, PFDR = 0.152), CD38 on igd+ cd24- (OR = 1.14, 95% CI = 1.06-1.23, p = 0.001, PFDR = 0.152), D14+ cd16+ monocyte %monocyte (OR = 1.10, 95% CI = 1.04-1.17, p = 0.001, PFDR = 0.159). Additionally, PD may be causally related to the immune phenotype of CM CD8br %T cell (beta = 0.10, 95% CI = 1.14-1.16, p = 0.0004, PFDR = 0.151), SSC-A on monocyte (beta = 0.11, 95% CI = 1.15-1.18, p = 0.0004, PFDR = 0.1 SSC-A on monocyte). No pleiotropy was determined.

Conclusion

This study suggested a potential causal link between immune cells and Parkinson's Disease through the MR method, which could provide a new direction for the mechanistic research and clinical treatment of PD.

Withania somnifera (L.) Dunal, a Potential Source of Phytochemicals for Treating Neurodegenerative Diseases: A Systematic Review

Withania somnifera (L.) Dunal is a medicinal plant belonging to the traditional Indian medical system, showing various therapeutic effects such as anti-cancer, anti-inflammatory, anti-microbial, anti-diabetic, and hepatoprotective activity. Of great interest is W. somnifera's potential beneficial effect against neurodegenerative diseases, since the authorized medicinal treatments can only delay disease progression and provide symptomatic relief and are not without side effects. A systematic search of PubMed and Scopus databases was performed to identify preclinical and clinical studies focusing on the applications of W. somnifera in preventing neurodegenerative diseases. Only English articles and those containing the keywords (Withania somnifera AND "neurodegenerative diseases", "neuroprotective effects", "Huntington", "Parkinson", "Alzheimer", "Amyotrophic Lateral Sclerosis", "neurological disorders") in the title or abstract were considered. Reviews, editorials, letters, meta-analyses, conference papers, short surveys, and book chapters were not considered. Selected articles were grouped by pathologies and summarized, considering the mechanism of action. The quality assessment and the risk of bias were performed using the Cochrane Handbook for Systematic Reviews of Interventions checklist. This review uses a systematic approach to summarize the results from 60 investigations to highlight the potential role of W. somnifera and its specialized metabolites in treating or preventing neurodegenerative diseases.

Mechanistic insights into the role of amyloid-β in innate immunity

Colocalization of microbial pathogens and the β-amyloid peptide (Aβ) in the brain of Alzheimer's disease (AD) patients suggests that microbial infection may play a role in sporadic AD. Aβ exhibits antimicrobial activity against numerous pathogens, supporting a potential role for Aβ in the innate immune response. While mammalian amyloid is associated with disease, many bacteria form amyloid fibrils to fortify the biofilm that protects the cells from the surrounding environment. In the microbial AD hypothesis, Aβ aggregates in response to infection to combat the pathogen. We hypothesize that this occurs through toxic Aβ oligomers that contain α-sheet structure and form prior to fibrillization. De novo designed α-sheet peptides specifically bind to the α-sheet structure present in the oligomers of both bacterial and mammalian amyloidogenic proteins to neutralize toxicity and inhibit aggregation. Here, we measure the effect of E. coli on Aβ, including upregulation, aggregation, and toxicity. Additionally, we determined the effect of Aβ structure on E. coli amyloid fibrils, or curli comprised of the CsgA protein, and biofilm formation. We found that curli formation by E. coli increased Aβ oligomer production, and Aβ oligomers inhibited curli biogenesis and reduced biofilm cell density. Further, curli and biofilm inhibition by Aβ oligomers increased E. coli susceptibility to gentamicin. Toxic oligomers of Aβ and CsgA interact via α-sheet interactions, neutralizing their toxicity. These results suggest that exposure to toxic oligomers formed by microbial pathogens triggers Aβ oligomer upregulation and aggregation to combat infection via selective interactions between α-sheet oligomers to neutralize toxicity of both species with subsequent inhibition of fibrillization.

Causal relationships between Sjögren's syndrome and Parkinson's disease: A Mendelian randomization study

BACKGROUND

Epidemiological and observational studies have indicated an association between Sjögren's syndrome (SS) and Parkinson's disease (PD). However, consistent conclusions have not been reached due to various limitations. In order to determine whether SS and PD are causally related, we conducted a Mendelian randomization study (MR) with two samples.

METHODS

Data for SS derived from the FinnGen consortium's R9 release (2495 cases and 365 533 controls). Moreover, data for PD were acquired from the publicly available GWAS of European ancestry, which involved 33 674 cases and 449 056 controls. The inverse variance weighted, along with four other effective methodologies, were employed to comprehensively infer the causal relationships between SS and PD. To assess the estimation's robustness, a number of sensitivity studies were performed. To determine the probability of reverse causality, we performed a reverse MR analysis.

RESULTS

There was no evidence of a significant causal effect of SS on PD risks based on the MR [odds ratio (OR) = 1.03; 95% confidence interval (CI) = 0.95-1.11; p = .45]. Similarly, no evidence supported the causal effects of PD on SS (OR = 0.92; 95% CI = 0.81-1.04; p = .20). These findings held up under rigorous sensitivity analysis.

CONCLUSIONS

MR bidirectional analysis did not reveal any cause-and-effect relationship between SS and PD, or vice versa. Further study of the mechanisms that may underlie the probable causal association between SS and PD is needed.

Systemic inflammation and risk of Parkinson's disease: A prospective cohort study and genetic analysis

BACKGROUND

Multiple evidence has suggested the complex interplay between Parkinson's disease (PD) and systemic inflammation marked by C-reactive protein (CRP) and interleukin 6 (IL-6). Nevertheless, the findings across studies have shown inconsistency, and the direction of the effect remains controversial. Here, we aimed to explore the link between CRP and IL-6 and the risk of PD.

METHODS

Based on data from the UK Biobank, we investigated the association between baseline CRP and IL-6 and the risk of incident PD with Cox proportional hazards regression analysis. We further performed extensive genetic analyses including genetic correlation, polygenic risk score (PRS), and pleiotropic enrichment based on summary statistics from previous genome-wide association studies.

RESULTS

A higher level of CRP at baseline was associated with a lower risk of PD (HR = 0.85, 95 % CI: 0.79-0.90, P = 4.23E-07). The results remained consistent in the subgroup analyses stratified by sex, age and body mass index. From the genetic perspective, a significant negative genetic correlation was identified between CRP and PD risk (correlation: -0.14, P = 6.31E-05). Higher PRS of CRP was associated with a lower risk of PD (P = 0.015, beta = -0.04, SE = 0.017). Moreover, we observed significant pleiotropic enrichment for PD conditional on CRP, and identified 13 risk loci for PD, some of which are implicated in immune functionality and have been linked to PD, including CTSB, HNF4A, PPM1G, ACMSD, and NCOR1. In contrast, no significant association was identified between IL-6 and PD.

CONCLUSIONS

Systemic inflammation at baseline measured by CRP level is associated with decreased future risk of PD. These discoveries contribute to a deeper comprehension of the role of inflammation in the risk of PD, and hold implications for the design of therapeutic interventions in clinical trials.