Systemic activation of NLRP3 inflammasome and plasma α-synuclein levels are correlated with motor severity and progression in Parkinson's disease

Structure based design, synthesis and identification of novel covalent reversible dual TLR2/TLR9 small molecule antagonists

Inflammation is a key driver of the onset and progression of neurodegenerative diseases and cancer and can be caused by aggregated proteins, injured neurons or synapses, dysregulation of inflammatory control mechanisms, and other factors. Tolllike receptors (TLRs) are important mediators of inflammatory pathways, and their activation leads to pro-inflammatory cytokine release by immune cells in the periphery or in the central nervous system (CNS). TLR2 and TLR9 are implicated in the inflammatory pathogenesis of CNS degenerative diseases such as Parkinson's Disease (PD) and amyotrophic lateral sclerosis (ALS). They are also held to be important in the etiology of certain malignancies like inflammatory pancreatic ductal adenocarcinoma and glioblastoma. Inactivation of TLR2/9 in animal models of neurodegeneration has reduced pathological markers and diminished neuronal loss, while in animal models of cancer it has suppressed tumors. Therefore, TLR2 and TLR9 may be potential targets for the treatment of neurodegenerative disorders and cancers. We identified for the first time a key binding locus in TLR2/9 TIR domain which guided reversible covalent drug (RCD) design of a novel, first-in class series of dual TLR2/9 antagonists. Sub-micromolar antagonist concentrations potently inhibited TLR2 and TLR9 signaling induced by TLR2/9 specific agonists. Importantly, this series of antagonists did not discernably activate other TLRs and exhibited favorable in-vitro ADME and safety. The analogs described here may help realize effective TLR2/9 antagonism as a viable therapeutic strategy for inflammation driven CNS diseases and various malignancies with an inflammatory etiology.

α-Synuclein in Parkinson's Disease: From Bench to Bedside

α-Synuclein (α-syn), a pathological hallmark of PD, is emerging as a bridging element at the crossroads between neuro/immune-inflammatory responses and neurodegeneration in PD. Several evidence show that pathological α-syn accumulates in neuronal and non-neuronal cells (i.e., neurons, microglia, macrophages, skin cells, and intestinal cells) in central and peripheral tissues since the prodromal phase of the disease, contributing to brain pathology. Indeed, pathological α-syn deposition can promote neurogenic/immune-inflammatory responses that contribute to systemic and central neuroinflammation associated with PD. After providing an overview of the structure and functions of physiological α-syn as well as its pathological forms, we review current studies about the role of neuronal and non-neuronal α-syn at the crossroads between neuroinflammation and neurodegeneration in PD. In addition, we provide an overview of the correlation between the accumulation of α-syn in central and peripheral tissues and PD, related symptoms, and neuroinflammation. Special attention was paid to discussing whether targeting α-syn can represent a suitable therapeutical approach for PD.

The interplay between α-synuclein aggregation and necroptosis in Parkinson's disease: a spatiotemporal perspective

Parkinson's disease (PD) is a common neurodegenerative disorder characterized by the death of dopaminergic neurons and the aggregation of alpha-synuclein (α-Syn). It presents with prominent motor symptoms, and by the time of diagnosis, a significant number of neurons have already been lost. Current medications can only alleviate symptoms but cannot halt disease progression. Studies have confirmed that both dopaminergic neuronal loss and α-Syn aggregation are associated with necroptosis mechanisms. Necroptosis, a regulated form of cell death, has been recognized as an underexplored hotspot in PD pathogenesis research. In this review, we propose a spatiotemporal model of PD progression, highlighting the interactions between α-Syn aggregation, mitochondrial dysfunction, oxidative stress, neuroinflammation and necroptosis. These processes not only drive motor symptoms but also contribute to early non-motor symptoms, offering insights into potential diagnostic markers. Finally, we touch upon the therapeutic potential of necroptosis inhibition in enhancing current PD treatments, such as L-Dopa. This review aims to provide a new perspective on the pathogenesis of PD and to identify avenues for the development of more effective therapeutic strategies.

NLRP3 inflammasome in neuroinflammation and central nervous system diseases

Neuroinflammation plays an important role in the pathogenesis of various central nervous system (CNS) diseases. The NLRP3 inflammasome is an important intracellular multiprotein complex composed of the innate immune receptor NLRP3, the adaptor protein ASC, and the protease caspase-1. The activation of the NLRP3 inflammasome can induce pyroptosis and the release of the proinflammatory cytokines IL-1β and IL-18, thus playing a central role in immune and inflammatory responses. Recent studies have revealed that the NLRP3 inflammasome is activated in the brain to induce neuroinflammation, leading to further neuronal damage and functional impairment, and contributes to the pathological process of various neurological diseases, such as multiple sclerosis, Parkinson's disease, Alzheimer's disease, and stroke. In this review, we summarize the important role of the NLRP3 inflammasome in the pathogenesis of neuroinflammation and the pathological course of CNS diseases and discuss potential approaches to target the NLRP3 inflammasome for the treatment of CNS diseases.

Targeting the NLRP3 inflammasome in Parkinson's disease: From molecular mechanism to therapeutic strategy

Parkinson's disease is the second most common neurodegenerative disease, characterized by substantial loss of dopaminergic (DA) neurons, the formation of Lewy bodies (LBs) in the substantia nigra, and pronounced neuroinflammation. The nucleotide-binding domain like leucine-rich repeat- and pyrin domain-containing protein 3 (NLRP3) inflammasome is one of the pattern recognition receptors (PRRs) that function as intracellular sensors in response to both pathogenic microbes and sterile triggers associated with Parkinson's disease. These triggers include reactive oxygen species (ROS), misfolding protein aggregation, and potassium ion (K+) efflux. Upon activation, it recruits and activates caspase-1, then processes the pro-inflammatory cytokines interleukin-1β (IL-1β) and IL-18, which mediate neuroinflammation in Parkinson's disease. In this review, we provide a comprehensive overview of NLRP3 inflammasome, detailing its structure, activation pathways, and the factors that trigger its activation. We also explore the pathological mechanisms by which NLRP3 contributes to Parkinson's disease and discuss potential strategies for targeting NLRP3 as a therapeutic approach.

New Insights on the Potential Role of Pyroptosis in Parkinson's Neuropathology and Therapeutic Targeting of NLRP3 Inflammasome with Recent Advances in Nanoparticle-Based miRNA Therapeutics

Parkinson's disease (PD) is a widespread neurodegenerative disorder characterized by the gradual degeneration of dopaminergic neurons in the substantia nigra pars compacta (SNc). This review aims to summarize the recent advancements in the pathophysiological mechanisms of pyroptosis, mediated by NLRP3 inflammasome, in advancing PD and the anti-pyroptotic agents that target NLRP3 inflammatory pathways and miRNA. PD pathophysiology is primarily linked to the aggregation of α-synuclein, the overproduction of reactive oxygen species (ROS), and the development of neuroinflammation due to microglial activation. Prior research indicated that a significant quantity of microglia is activated in both PD patients and 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine (MPTP) mouse models, triggering neuroinflammation and resulting in a cascade of cellular death. Microglia possess an inflammatory complex pathway termed the nucleotide-binding oligomerization domain-, leucine-rich repeat, and pyrin domain-containing 3 (NLRP3) inflammasome. Activation of the NLRP-3 inflammasome results in innate cytokines maturation, including IL-18 and IL-1β, which initiates the neuroinflammatory signal and induces a type of inflammatory cell death known as pyroptosis. Upon neuronal damage, intracellular levels of damage-associated molecular patterns (DAMPs), including reactive oxygen species (ROS), would build. DAMPs induce unregulated cell death and subsequent release of oxidative intermediates and pro-inflammatory cytokines, leading to the progression of PD. Thus, targeting of neuroinflammation using antipyroptotic medications can be efficiently achieved by blocking NLRP3 and obstructing IL-1β signaling and release. Furthermore, many research studies showed that miRNAs have been identified as regulators of the NLRP3 inflammasome and Nrf2 signal, which subsequently modulate the NLRP3-Nrf2 axis in PD. Nanotechnology promises potential for the advancement of miRNA-based therapies. Nanoparticles that ensure miRNA stability, traverse the blood-brain barrier (BBB) and distribute miRNA targeting regions needed to be created. In conclusion, targeting the pyroptosis pathway via NLRP3 or miRNA may serve as a prospective therapeutic strategy for PD in the future.

α-Synuclein orchestrates Th17 responses as antigen and adjuvant in Parkinson's disease

Recently, the role of T cells in the pathology of α-synuclein (αS)-mediated neurodegenerative disorders called synucleinopathies, including Parkinson's disease (PD), dementia with Lewy bodies (DLB), and multiple system atrophy, has attracted increasing attention. Although the existence of αS-specific T cells and the immunogenicity of the post-translationally modified αS fragment have been reported in PD and DLB, the key cellular subset associated with disease progression and its induction mechanism remain largely unknown.Peripheral blood mononuclear cells (PBMCs) from synucleinopathy patients and healthy controls were cultured in the presence of the αS peptide pools. Cytokine analysis using culture supernatants revealed that C-terminal αS peptides with a phosphorylated serine 129 residue (pS129), a feature of pathological αS aggregates, promoted the production of IL-17A, IL-17F, IL-22, IFN-γ and IL-13 in PD patients compared with that in controls. In pS129 peptide-reactive PD cases, Ki67 expression was increased in CD4 T cells but not in CD8 T cells, and intracellular cytokine staining assay revealed the existence of pS129 peptide-specific Th1 and Th17 cells. The pS129 peptide-specific Th17 responses, but not Th1 responses, demonstrated a positive correlation with the Movement Disorder Society-Unified Parkinson's Disease Rating Scale (MDS-UPDRS) Part III scores. A similar correlation was observed for IL-17A levels in the culture supernatant of PBMCs from PD patients with disease duration < 10 years. Interestingly, enhanced Th17 responses to pS129 peptides were uniquely found in PD patients among the synucleinopathies, suggesting that Th17 responses are amplified by certain mechanisms in PD patients. To investigate such mechanisms, we analyzed Th17-inducible capacity of αS-exposed dendritic cells (DCs). In vitro stimulation with αS aggregates generated Th17-inducible DCs with IL-6 and IL-23 production through the signaling of TLR4 and spliced X-box binding protein-1 (XBP1s). In fact, the levels of IL-6 and IL-23 in plasma, and the XBP1s ratio in type 2 conventional DCs were increased in PD patients compared with those in controls.Here, we propose the importance of αS-specific Th17 responses in the progression of PD and the underlying mechanisms inducing Th17 responses. These findings may provide novel therapeutic strategies to prevent disease development through the suppression of TLR4-XBP1s-IL-23 signaling in DCs.

Curcumin prevents neurodegeneration by blocking HDAC6-NLRP3 pathway-dependent neuroinflammation in Parkinson's disease

Curcumin is a hydrophobic polyphenolic compound with potent anti-inflammatory properties. However, whether it can achieve therapeutic effects by alleviating neuroinflammation in patients with Parkinson's disease (PD) and its potential mechanism are still unknown. This study explored the effects of curcumin on neuroinflammation in dopaminergic neurons and deciphered its direct target in the histone deacetylase 6 (HDAC6)-Nucleotide-binding domain, leucine-rich repeat, and pyrin domain-containing protein 3 (NLRP3) pathway, revealing the potential role of curcumin in the treatment of Parkinson's disease. Here, we show that curcumin alleviated the degeneration of neurons in a PD model by mitigating the activation of the NLRP3-mediated inflammatory response both in vivo and in vitro. Furthermore, we discovered that curcumin prevented neuroinflammation by blocking the HDAC6-NLRP3 pathway in a PD model. Moreover, overexpression of HDAC6 could eliminate the effect of curcumin on the neuroinflammatory response mediated by NLRP3. Curcumin and the HDAC6 inhibitor WT161 could alleviate neurodegeneration. In addition, activated HDAC6 directly deacetylated NLRP3 at lysine 84 to maintain its stability, which increased the inflammatory response and promoted neurodegeneration. These findings show that curcumin, a neuroinflammation inhibitor, blocks neurodegeneration via the HDAC6-NLRP3 pathway and represents a potentially practical pharmacological approach for treating neuroinflammation-driven neurodegenerative diseases. For the first time, HDAC6 was shown to directly regulate the acetylation of NLRP3.

Microglial NLRP3-gasdermin D activation impairs blood-brain barrier integrity through interleukin-1β-independent neutrophil chemotaxis upon peripheral inflammation in mice

Blood-brain barrier (BBB) disintegration is a key contributor to neuroinflammation; however, the biological processes governing BBB permeability under physiological conditions remain unclear. Here, we investigate the role of NLRP3 inflammasome in BBB disruption following peripheral inflammatory challenges. Repeated intraperitoneal lipopolysaccharide administration causes NLRP3-dependent BBB permeabilization and myeloid cell infiltration into the brain. Using a mouse model with cell-specific hyperactivation of NLRP3, we identify microglial NLRP3 activation as essential for peripheral inflammation-induced BBB disruption. Conversely, NLRP3 and microglial gasdermin D (GSDMD) deficiency markedly attenuates lipopolysaccharide-induced BBB breakdown. Notably, IL-1β is not required for NLRP3-GSDMD-mediated BBB disruption. Instead, microglial NLRP3-GSDMD axis upregulates CXCL chemokines and matrix metalloproteinases around BBB via producing GDF-15, promoting the recruitment of CXCR2-containing neutrophils. Inhibition of neutrophil infiltration and matrix metalloproteinase activity significantly reduces NLRP3-mediated BBB impairment. Collectively, these findings reveal the important role of NLRP3-driven chemokine production in BBB disintegration, suggesting potential therapeutic targets to mitigate neuroinflammation.

Crosstalk between SIRT1/Nrf2 signaling and NLRP3 inflammasome/pyroptosis as a mechanistic approach for the neuroprotective effect of linagliptin in Parkinson's disease

In recent years, special attention has been paid to highlighting the antiparkinsonian effect of linagliptin. However, the mechanism of its action has not yet been well investigated. The present study aimed to verify the neuroprotective effect of linagliptin in the rotenone model of Parkinson's disease (PD) and further explore its potential molecular mechanisms. Rats were intoxicated with rotenone (2 mg/kg/day; sc) and treated with linagliptin (10  mg/kg/day; po) for 14 consecutive days. The present finding showed that linagliptin ameliorated the histopathological changes of rotenone on substantia nigra and striata. Linagliptin decreased α-synuclein immunoreactivity along with an increase in tyrosine hydroxylase immunoreactivity and striatal dopamine content. This was reflected in the marked improvement of the behavior and motor deficits in rotenone-intoxicated rats. On the molecular level, linagliptin upregulated sirtuin 1 (SIRT1)/ nuclear factor erythroid 2-related factor 2 (Nrf2) signaling, reduced ionized calcium-binding adaptor molecule 1 (Iba1) protein expression, restored glutathione (GSH) content, and elevated heme oxygenase-1 (HO-1) level in rats with rotenone intoxication. Moreover, linagliptin inhibited NOD-like receptor protein 3 (NLRP3)/caspase-1/interleukin-1β (IL-1β) cascade with subsequent reduction in gasdermin D (GSDMD) expression. Therefore, the present study reveals the ability of linagliptin, through the activation of SIRT1/Nrf2 signaling, to suppress NLRP3 inflammasome-mediated pyroptosis and protect against rotenone-induced parkinsonism.

Potential Biomarkers and Treatment of Neuroinflammation in Parkinson's Disease

Parkinson's disease (PD) is a degenerative disease of the central nervous system primarily affecting middle-aged and elderly individuals, significantly compromising their quality of life. Neuroinflammation is now recognized as a key feature in the pathogenesis of PD. This study reviews recent advances in the identification of potential biomarkers associated with neuroinflammation in PD and their significance for therapeutic strategies. These findings suggest that inflammatory factors play a pivotal role in PD treatment, and interventions involving anti-inflammatory drugs, physical exercise, and dietary modifications have shown promising results in mitigating disease progression.

α-Synuclein pathology as a target in neurodegenerative diseases

α-Synuclein misfolds into pathological forms that lead to various neurodegenerative diseases known collectively as α-synucleinopathies. In this Review, we provide a comprehensive overview of pivotal advances in α-synuclein research. We examine structural features and physiological functions of α-synuclein and summarize current insights into key post-translational modifications, such as nitration, phosphorylation, ubiquitination, sumoylation and truncation, considering their contributions to neurodegeneration. We also highlight the existence of disease-specific α-synuclein strains and their mechanisms of pathological spread, and discuss seed amplification assays and PET tracers as emerging diagnostic tools for detecting pathological α-synuclein in clinical settings. We also discuss α-synuclein aggregation and clearance mechanisms, and review cell-autonomous and non-cell-autonomous processes that contribute to neuronal death, including the roles of adaptive and innate immunity in α-synuclein-driven neurodegeneration. Finally, we highlight promising therapeutic approaches that target pathological α-synuclein and provide insights into emerging areas of research.

Neuroinflammation-mediated white matter injury in Parkinson's disease and potential therapeutic strategies targeting NLRP3 inflammasome

Parkinson's disease (PD) is the second most common neurodegenerative disease in the world, severely affecting the quality of life of patients. Recent studies have shown that white matter (WM) plays a vital role in higher neurological functions such as behavior and cognition. In PD patients, neurodegeneration occurs not only in neuronal soma, but also in WM fiber bundles, which are composed of neural axons. The clinical symptoms of PD patients are related not only to the degeneration of neuronal soma, but also to the degeneration of WM. Most previous studies have focused on neuronal soma in substantia nigra (SN), while WM injury (WMI) in PD has been less studied. Moreover, most previous studies have focused on intracerebral lesions in PD, while less attention has been paid to the spinal cord distal to the brain. The above-mentioned factors may be one of the reasons for the poor treatment of previous drug outcomes. Neuroinflammation has been shown to exert a significant effect on the pathological process of brain and spinal cord neurodegeneration in PD. The NOD-like receptor family, pyrin domain-containing 3 (NLRP3) inflammasome has been shown to activate and mediate neuroinflammation and exacerbate neurodegeneration in PD. NLRP3 inflammasome inhibition may be a potential strategy for the treatment of WMI in PD. This review summarizes recent advances and future directions regarding neuroinflammation-mediated WMI in PD and potential therapeutic strategies for targeting NLRP3 inflammasome in the brain and spinal cord, providing new insights for researchers to develop more effective therapeutic approaches for PD patients.

Inflammasomes in neurodegenerative diseases

Inflammasomes represent a crucial component of the innate immune system, which respond to threats by recognizing different molecules. These are known as pathogen-associated molecular patterns (PAMPs) or host-derived damage-associated molecular patterns (DAMPs). In neurodegenerative diseases and neuroinflammation, the accumulation of misfolded proteins, such as beta-amyloid and alpha-synuclein, can lead to inflammasome activation, resulting in the release of interleukin (IL)-1β and IL-18. This activation also induces pyroptosis, the release of inflammatory mediators, and exacerbates neuroinflammation. Increasing evidence suggests that inflammasomes play a pivotal role in neurodegenerative diseases. Therefore, elucidating and investigating the activation and regulation of inflammasomes in these diseases is of paramount importance. This review is primarily focused on evidence indicating that inflammasomes are activated through the canonical pathway in these diseases. Inflammasomes as potential targets for treating neurodegenerative diseases are also discussed.

Integrating bioinformatics and machine learning to uncover lncRNA LINC00269 as a key regulator in Parkinson's disease via pyroptosis pathways

BACKGROUND

Pyroptosis, a specific type of programmed cell death, which has become a significant factor to Parkinson's disease (PD). Concurrently, long non-coding RNAs (lncRNAs) have garnered attention for their regulatory roles in neurodegenerative disorders. This study was designed to ascertain the key lncRNAs in pyroptosis pathways of PD and elucidate their regulatory mechanisms.

METHODS

Employing a combination of bioinformatics and machine learning, we analyzed PD data sets GSE133347 and GSE110716. Gene Ontology (GO) and Kyoto Encyclopedia of Genes and Genomes (KEGG) recognized different lncRNAs. Through various algorithms such as Least Absolute Shrinkage and Selection Operator (LASSO), Random Forest (RF), and Weighted Gene Co-expression Network Analysis (WGCNA), we recognized LINC01606 and LINC00269, which are key factors during the emergence and development of PD. Furthermore, experimental validation was conducted in PD mouse models to confirm these bioinformatics findings.

RESULTS

The analysis showed that there were a large number of apoptosis-related gene expression changes in Parkinson's syndrome, for example, CASP1 and GSDME were up-regulated, and CASP9 and AIM2 were down-regulated. Among the lncRNAs, LINC01606 and LINC00269 were identified as potential modulators of pyroptosis. Notably, LINC00269 was observed to be significantly downregulated in the brain tissues of a PD mouse model, supporting its involvement in PD. The study also highlighted potential interactions of these lncRNAs with genes like ONECUT2, PRLR, CTNNA3, and LRP2.

CONCLUSIONS

This study identifies LINC00269 as a potential contributor to pyroptosis pathways in PD. While further investigation is required to fully elucidate its role, these findings provide new insights into PD pathogenesis and suggest potential avenues for future research on diagnostic and therapeutic targets. The study underscores the importance of integrating bioinformatics with experimental validation in neurodegenerative disease research.

Impact of Mast Cell Activation on Neurodegeneration: A Potential Role for Gut-Brain Axis and Helicobacter pylori Infection

BACKGROUND

The innate immune response aims to prevent pathogens from entering the organism and/or to facilitate pathogen clearance. Innate immune cells, such as macrophages, mast cells (MCs), natural killer cells and neutrophils, bear pattern recognition receptors and are thus able to recognize common molecular patterns, such as pathogen-associated molecular patterns (PAMPs), and damage-associated molecular patterns (DAMPs), the later occurring in the context of neuroinflammation. An inflammatory component in the pathology of otherwise "primary cerebrovascular and neurodegenerative" disease has recently been recognized and targeted as a means of therapeutic intervention. Activated MCs are multifunctional effector cells generated from hematopoietic stem cells that, together with dendritic cells, represent first-line immune defense mechanisms against pathogens and/or tissue destruction.

METHODS

This review aims to summarize evidence of MC implication in the pathogenesis of neurodegenerative diseases, namely, Alzheimer's disease, Parkinson's disease, amyotrophic lateral sclerosis, Huntington's disease, and multiple sclerosis.

RESULTS

In view of recent evidence that the gut-brain axis may be implicated in the pathogenesis of neurodegenerative diseases and the characterization of the neuroinflammatory component in the pathology of these diseases, this review also focuses on MCs as potential mediators in the gut-brain axis bi-directional communication and the possible role of Helicobacter pylori, a gastric pathogen known to alter the gut-brain axis homeostasis towards local and systemic pro-inflammatory responses.

CONCLUSION

As MCs and Helicobacter pylori infection may offer targets of intervention with potential therapeutic implications for neurodegenerative disease, more clinical and translational evidence is needed to elucidate this field.

LncRNA KCNQ1OT1 promotes NLRP3 inflammasome activation in Parkinson's disease by regulating pri-miR-186/mature miR-186/NLRP3 axis

Increasing evidence indicated that neuroinflammation was involved in progression of Parkinson's disease (PD). Long noncoding RNAs (lncRNAs) played important roles in regulating inflammatory processes in multiple kinds of human diseases such as cancer diabetes, cardiomyopathy, and neurodegenerative disorders. The mechanisms by which lncRNAs regulated PD related inflammation and dopaminergic neuronal loss have not yet been fully elucidated. In current study, we intended to explore the function and potential mechanism of lncRNA KCNQ1 opposite strand/antisense transcript 1 (KCNQ1OT1) in regulating inflammasome activation in PD. Functional assays confirmed that knockdown of KCNQ1OT1 suppress microglial NLR family pyrin domain containing 3 (NLRP3) inflammasome activation and attenuated dopaminergic neuronal loss in PD model mice. As KCNQ1OT1 located in both cytoplasm and nucleus of microglia, we demonstrated that KCNQ1OT1 promoted microglial NLRP3 inflammasome activation by competitive binding with miR-186 in cytoplasm and inhibited pri-miR-186 mediated NLRP3 silencing through recruitment of DiGeorge syndrome critical region gene 8 (DGCR8) in nucleus, respectively. Our study found a novel lncRNA-pri-miRNA/mature miRNA-mRNA regulatory network in microglia mediated NLRP3 inflammasome activation and dopaminergic neuronal loss, provided further insights for the treatment of Parkinson's disease.

Neuroinflammation in Age-Related Neurodegenerative Diseases: Role of Mitochondrial Oxidative Stress

A shared hallmark of age-related neurodegenerative diseases is the chronic activation of innate immune cells, which actively contributes to the neurodegenerative process. In Alzheimer's disease, this inflammatory milieu exacerbates both amyloid and tau pathology. A similar abnormal inflammatory response has been reported in Parkinson's disease, with elevated levels of cytokines and other inflammatory intermediates derived from activated glial cells, which promote the progressive loss of nigral dopaminergic neurons. Understanding the causes that support this aberrant inflammatory response has become a topic of growing interest and research in neurodegeneration, with high translational potential. It has been postulated that the phenotypic shift of immune cells towards a proinflammatory state combined with the presence of immunogenic cell death fuels a vicious cycle in which mitochondrial dysfunction plays a central role. Mitochondria and mitochondria-generated reactive oxygen species are downstream effectors of different inflammatory signaling pathways, including inflammasomes. Dysfunctional mitochondria are also recognized as important producers of damage-associated molecular patterns, which can amplify the immune response. Here, we review the major findings highlighting the role of mitochondria as a checkpoint of neuroinflammation and immunogenic cell deaths in neurodegenerative diseases. The knowledge of these processes may help to find new druggable targets to modulate the inflammatory response.

The potential role of CGRP in synuclein-associated neurodegenerative disorders

In this hypothesis article, the potential clinicopathological associations of Calcitonin Gene Related Peptide (CGRP) with the development of synuclein-associated neurodegenerative disorders (SAND) are discussed. The presence of α-syn and CGRP in the CNS and the ENS and the intricate role of CGRP and its related pathways in inflammation, apoptosis, metabolism, neuromodulation, and brain-gut communication are analyzed. Since this hypothesis is confirmed, modulating CGRP-potential related pathways may lead to novel disease-modifying therapies.

Unveiling Parkinson's disease through biomarker research: current insights and future prospects

Parkinson's disease (PD) is a neurodegenerative condition marked by the gradual depletion of dopaminergic neurons in the substantia nigra. Despite substantial strides in comprehending potential causative mechanisms, the validation of biomarkers with unequivocal evidence for routine clinical application remains elusive. Consequently, the diagnosis heavily relies on patients' clinical assessments and medical backgrounds. The imperative need for diagnostic and prognostic biomarkers arises due to the prevailing limitations of treatments, which predominantly address symptoms without modifying the disease course. This comprehensive review aims to elucidate the existing landscape of diagnostic and prognostic biomarkers for PD, drawing insights from contemporary literature.

Expression of NLRP3 in serum and induced sputum of children with asthma and their relationship with disease severity

OBJECTIVES

The aim of this cross-sectional study is to investigate the levels of NLRP3 in the serum and induced sputum of children with asthma and their potential association with lung function and disease severity.

METHODS

This cross-sectional study included 83 children with bronchial asthma who sought medical care at our hospital from May 2023 to February 2024. Portable spirometry was used to monitor lung function parameters, including forced vital capacity, forced expiratory volume in 1 s, peak expiratory flow. The expression of C-reactive protein (CRP), interleukin (IL)-6, IL-1β, TNF-α, and Nod-like receptor family pyrin domain-containing 3 (NLRP3) in the serum and induced sputum were measured by enzyme-linked immunosorbent assay. Data analysis was performed using SPSS 25.0 and differences with P < 0.05 were considered statistically significant.

RESULTS

Children with asthma exhibited significantly elevated levels of serum NLRP3, CRP, IL-6, IL-1β, and TNF-α compared to healthy controls. In addition, children with moderate-severe asthma had significantly higher levels of serum and induced sputum NLRP3 and IL-1β compared to children with mild asthma. Spearman's correlation analysis revealed a positive correlation between induced sputum NLRP3 and IL-6. Moreover, induced sputum NLRP3 was negatively correlated with lung function parameters. The results of receiver operating characteristic curves showed that induced sputum NLRP3 could be used for diagnosing children with moderate-severe asthma, with an AUC was 0.758, cutoff value of 3.33 ng/mL, sensitivity of 66.1%, and specificity of 70.8%. Furthermore, the logistic regression analysis revealed that serum and induced sputum NLRP3, induced sputum IL-6 and IL-1β were risk factors for children with moderate-severe asthma.

CONCLUSIONS

In this cross-sectional study, we found a significant increase in NLRP3 levels in induced sputum of children with asthma, which further increased in those with moderate-severe disease. The levels of NLRP3 in induced sputum could serve as potential biomarkers for assessing disease severity.

Parkinson's disease models and death signaling: what do we know until now?

Parkinson's disease (PD) is the second neurodegenerative disorder most prevalent in the world, characterized by the loss of dopaminergic neurons in the Substantia Nigra (SN). It is well known for its motor and non-motor symptoms including bradykinesia, resting tremor, psychiatric, cardiorespiratory, and other dysfunctions. Pathological apoptosis contributes to a wide variety of diseases including PD. Various insults and/or cellular phenotypes have been shown to trigger distinct signaling events leading to cell death in neurons affected by PD. The intrinsic or mitochondrial pathway, inflammatory or oxidative stress-induced extrinsic pathways are the main events associated with apoptosis in PD-related neuronal loss. Although SN is the main brain area studied so far, other brain nuclei are also affected by the disease leading to non-classical motor symptoms as well as non-motor symptoms. Among these, the respiratory symptoms are often overlooked, yet they can cause discomfort and may contribute to patients shortened lifespan after disease diagnosis. While animal and in vitro models are frequently used to investigate the mechanisms involved in the pathogenesis of PD in both the SN and other brain regions, these models provide only a limited understanding of the disease's actual progression. This review offers a comprehensive overview of some of the most studied forms of cell death, including recent research on potential treatment targets for these pathways. It highlights key findings and milestones in the field, shedding light on the potential role of understanding cell death in the prevention and treatment of the PD. Therefore, unraveling the connection between these pathways and the notable pathological mechanisms observed during PD progression could enhance our comprehension of the disease's origin and provide valuable insights into potential molecular targets for the developing therapeutic interventions.

The NLRP3 inflammasome: Mechanisms of activation, regulation, and role in diseases

Because of numerous stress signals, intracellular protein complexes are called inflammasomes. They function as catalysts for the proteolytic transformation of pro-interleukin into the active form of interleukin. Inflammasomes can promote a type of cell death process known as pyroptosis. The NLRP3 inflammasome, comprised of the NLRP3 protein, procaspase-1, and ASC, tightly regulates inflammation. The NLRP3 inflammasome is activated by a variety of stimuli, and several molecular and cellular events, such as ion influx, mitochondrial dysfunction, reactive oxygen species production, and lysosomal damage have been shown to trigger its activation. Inflammation plays a major role in almost all types of human diseases. The NLRP3 inflammasome has been the most widely studied and plays an important pathogenic role in various inflammatory pathologies. This review briefly presents the basic features of NLRP3 inflammasome and their mechanisms of activation and regulation. In addition, recent studies report the role of NLRP3 inflammasome in several diseases have been summarized.

Atractylenolide-I Ameliorates Motor Deficits and Reduces Inflammation of the Spinal Cord by SIRT1/PGC-1α Pathway in MPTP Subacute Mouse Model of Parkinson's Disease

Background

Parkinson's disease (PD) is a neurodegenerative movement disorder that impacts various systems, including the substantia nigra (SN) par compacta (SNpc) and extranigral regions like the spinal cord. The presence of persistent inflammation in the SN and spinal cord is associated with movement difficulties in PD. Atractylenolide-I (ATR-I) is a natural sesquiterpene recognized for its anti-inflammatory and neuroprotective effects. This research aimed to assess the impact of ATR-I treatment on motor function and inflammation in MPTP-induced subacute PD mice, particularly focusing on the role of ATR-I in spinal cord inflammation.

Methods

The motor functions of the mice were assessed using suspension and gait tests. Dopaminergic neuronal loss in the SNpc and microglial activation in both the SNpc and spinal cord were evaluated through immunofluorescence staining. The levels of inflammatory mediators in the spinal cord were measured using RT-qPCR analysis. The expressions of SIRT1 and PGC-1α in the spinal cord were analyzed through Western blotting and RT-qPCR.

Results

ATR-I treatment improved motor deficits in MPTP-induced mice. Moreover, ATR-I reduced the loss of dopamine neurons and microglial activation in the SNpc of MPTP-induced mice. Additionally, ATR-I suppressed spinal cord inflammation by decreasing microglial activation and the mRNA expression of TNF-α, IL-1β, and iNOS in MPTP-induced mice. Interestingly, ATR-I also upregulated SIRT1 and PGC-1α levels in the spinal cord of MPTP-induced mice.

Conclusion

These findings suggest that ATR-I exhibits anti-inflammatory and neuroprotective properties in PD. The attenuation of spinal cord inflammation via the SIRT1/PGC-1α pathway may contribute to enhancing motor function, highlighting ATR-I as a potential therapeutic avenue for PD.

The role of the gut microbiota in neurodegenerative diseases targeting metabolism

In recent years, the incidence of neurodegenerative diseases (NDs) has gradually increased over the past decades due to the rapid aging of the global population. Traditional research has had difficulty explaining the relationship between its etiology and unhealthy lifestyle and diets. Emerging evidence had proved that the pathogenesis of neurodegenerative diseases may be related to changes of the gut microbiota's composition. Metabolism of gut microbiota has insidious and far-reaching effects on neurodegenerative diseases and provides new directions for disease intervention. Here, we delineated the basic relationship between gut microbiota and neurodegenerative diseases, highlighting the metabolism of gut microbiota in neurodegenerative diseases and also focusing on treatments for NDs based on gut microbiota. Our review may provide novel insights for neurodegeneration and approach a broadly applicable basis for the clinical therapies for neurodegenerative diseases.

Glycation Produces Topologically Different α-Synuclein Oligomeric Strains and Modulates Microglia Response via the NLRP3-Inflammasome Pathway

α-Synuclein, a key player in Parkinson's disease and other synucleinopathies, possesses an inherently disordered structure that allows for versatile structural changes during aggregation. Microglia, the brain immune cells, respond differently to various α-synuclein strains, influencing their activation and release of harmful molecules, leading to neuronal death. Post-translational modifications, such as glycation in α-synuclein, add a layer of complexity to microglial activation. This study aimed to explore the impact of glycation on α-synuclein aggregation and microglial responses, which have not been studied before. Biophysical analyses revealed that glycated α-synuclein oligomers had distinct morphologies with a more negative and hydrophobic surface, preventing fibril formation and interfering with membrane interactions. Notably, there was increased cytosolic Ca2+ dysregulation, redox stress, and mitochondrial instability compared to cells exposed to unmodified α-synuclein oligomers. Additionally, glycated α-synuclein oligomers exhibited impaired binding to Toll-like receptor 2, compromising downstream signaling. Surprisingly, these oligomers promoted TLR4 endocytosis and degradation. In our experiments with oligomers, glycated α-synuclein oligomers preferred NLRP3 inflammasome-mediated neuroinflammation, contributing differently from unmodified α-synuclein oligomers. In summary, this study unveils the mechanism underlying the effect of glycation on α-synuclein oligomers and highlights the conformation-specific microglial responses toward extracellular α-synuclein.

Parkinson's disease is associated with clonal hematopoiesis with TET2 mutation

Clonal hematopoiesis of indeterminate potential (CHIP), a premalignant expansion of mutated hematopoietic stem cells, is linked to immune alterations. Given the role of neuroinflammation and immune dysfunction in Parkinson's disease (PD), we hypothesized a connection between CHIP and PD. We analyzed peripheral blood DNA from 341 PD, 92 isolated REM sleep behavior disorder (iRBD) patients, and 5003 controls using targeted sequencing of 24 genes associated with hematologic neoplasms. PD cases were classified by clinical progression mode: fast, slow, and typical. Using multivariable logistic regression models, CHIP prevalence was assessed against controls with a 1.0% variant allele fraction threshold. CHIP with TET2 mutations was more prevalent in PD than controls (aOR 1.75, 95% CI 1.11-2.77, p = 0.017), particularly in the fast motor progression subgroup (aOR 3.19, p = 0.004). No distinct associations were observed with iRBD. PD is linked to increased odds of CHIP with TET2 mutations, suggesting immune dysregulation in PD pathophysiology.

The genetic advantage of healthy centenarians: unraveling the central role of NLRP3 in exceptional healthspan

Despite extensive research into extending human healthspan (HS) and compressing morbidity, the mechanisms underlying aging remain elusive. However, a better understanding of the genetic advantages responsible for the exceptional HS of healthy centenarians (HC), who live in good physical and mental health for one hundred or more years, could lead to innovative health-extending strategies. This review explores the role of NLRP3, a critical component of innate immunity that significantly impacts aging. It is activated by pathogen-associated signals and self-derived signals that increase with age, leading to low-grade inflammation implicated in age-related diseases. Furthermore, NLRP3 functions upstream in several molecular aging pathways, regulates cellular senescence, and may underlie the robust health observed in HC. By targeting NLRP3, mice exhibit a phenotype akin to that of HC, the HS of monkeys is extended, and aging symptoms are reversed in humans. Thus, targeting NLRP3 could offer a promising approach to extend HS. Additionally, a paradigm shift is proposed. Given that the HS of the broader population is 30 years shorter than that of HC, it is postulated that they suffer from a form of accelerated aging. The term 'auto-aging' is suggested to describe accelerated aging driven by NLRP3.

Therapeutic Potential Effect of Glycogen Synthase Kinase 3 Beta (GSK-3β) Inhibitors in Parkinson Disease: Exploring an Overlooked Avenue

Parkinson's disease (PD) is a progressive neurodegenerative disease of the brain due to degeneration of dopaminergic neurons in the substantia nigra (SN). Glycogen synthase kinase 3 beta (GSK-3β) is implicated in the pathogenesis of PD. Therefore, the purpose of the present review was to revise the mechanistic role of GSK-3β in PD neuropathology, and how GSK-3β inhibitors affect PD neuropathology. GSK-3 is a conserved threonine/serine kinase protein that is intricate in the regulation of cellular anabolic and catabolic pathways by modulating glycogen synthase. Over-expression of GSK-3β is also interconnected with the development of different neurodegenerative diseases. However, the underlying mechanism of GSK-3β in PD neuropathology is not fully clarified. Over-expression of GSK-3β induces the development of PD by triggering mitochondrial dysfunction and oxidative stress in the dopaminergic neurons of the SN. NF-κB and NLRP3 inflammasome are activated in response to dysregulated GSK-3β in PD leading to progressive neuronal injury. Higher expression of GSK-3β in the early stages of PD neuropathology might contribute to the reduction of neuroprotective brain-derived neurotrophic factor (BDNF). Thus, GSK-3β inhibitors may be effective in PD by reducing inflammatory and oxidative stress disorders which are associated with degeneration of dopaminergic in the SN.

Association between osteoarthritis with Parkinson's disease in the US (NHANES 2011-2020)

Objected

To evaluate the association between osteoarthritis (OA) and Parkinson's disease (PD) in adults in the United States.

Methods

Using 2011-2020 NHANES data, a cross-sectional study of 11,117 adults over the age of 40 was conducted. Univariate logistic regression and multivariate logistic regression were used to analyze the relationship between arthritis and PD. In addition, stratified analysis was used to examine whether the relationship between arthritis and PD was interactive with age, gender, race, education, BMI.

Results

In this study, a total of 11,117 participants were included, and we found that osteoarthritis was positively correlated with the development of PD compared with non-arthritis patients [1.95 (1.44 ~ 2.62)] (p < 0.001). After adjusting the covariates, the results are still stable.

Conclusion

PD patients were positively correlated with OA. Among people with OA, there was a 95% increased risk of PD compared to people without arthritis. Therefore, when treating OA, attention should be paid to the increased risk of PD. In the meantime, further studies are needed to explore the link between OA and PD patients.

Implication of the LRR Domain in the Regulation and Activation of the NLRP3 Inflammasome

The NLRP3 inflammasome is a critical component of the innate immune response. NLRP3 activation is a tightly controlled process involving an initial priming to express NLRP3, pro-IL-1 β, and pro-IL-18, followed by an activation signal. The precise mechanism of activation is not fully understood due to the diverse range of activators, yet it effectively orchestrates the activation of caspase-1, which subsequently triggers the release of proinflammatory cytokines IL-1β and IL-18. NLRP3 dysregulation can lead to a variety of inflammatory diseases, highlighting its significant role in immune response and disease pathogenesis. NLRP3 is divided into three domains: the PYD, the NACHT, and the LRR domains. This review focuses on the LRR domain of NLRP3, detailing its structural characteristics, its function in pathogen sensing, its role in the degradation process, and its involvement in inflammasome auto-inhibition and activation. Additionally, we discuss the impact of mutations within the LRR domain found in atypical Cryopyrin-Associated Periodic Syndromes (CAPS), highlighting the clinical relevance of this domain.

Lack of genetic evidence for NLRP3 inflammasome involvement in Parkinson's disease pathogenesis

Activation of the NLRP3 inflammasome has been implicated in Parkinson's disease (PD) based on in vitro and in vivo studies. Clinical trials targeting the NLRP3 inflammasome in PD are ongoing. However, the evidence supporting NLRP3's involvement in PD from human genetics data is limited. We analyzed common and rare variants in NLRP3 inflammasome-related genes in PD cohorts, performed pathway-specific polygenic risk score (PRS) analyses, and studied causal associations using Mendelian randomization (MR) with the NLRP3 components and the cytokines IL-1β and IL-18. Our findings showed no associations of common or rare variants, nor of the pathway PRS with PD. MR suggests that altering the expression of the NLRP3 inflammasome, IL-1β, or IL-18, does not affect PD risk or progression. Therefore, our results do not support a role for the NLRP3 inflammasome in PD pathogenesis or as a target for drug development.

Fecal microbiota from patients with Parkinson's disease intensifies inflammation and neurodegeneration in A53T mice

AIMS

We evaluated the potential of Parkinson's disease (PD) fecal microbiota transplantation to initiate or exacerbate PD pathologies and investigated the underlying mechanisms.

METHODS

We transplanted the fecal microbiota from PD patients into mice by oral gavage and assessed the motor and intestinal functions, as well as the inflammatory and pathological changes in the colon and brain. Furthermore, 16S rRNA gene sequencing combined with metabolomics analysis was conducted to assess the impacts of fecal delivery on the fecal microbiota and metabolism in recipient mice.

RESULTS

The fecal microbiota from PD patients increased intestinal inflammation, deteriorated intestinal barrier function, intensified microglia and astrocyte activation, abnormal deposition of α-Synuclein, and dopaminergic neuronal loss in the brains of A53T mice. A mechanistic study revealed that the fecal microbiota of PD patients stimulated the TLR4/NF-κB/NLRP3 pathway in both the brain and colon. Additionally, multiomics analysis found that transplantation of fecal microbiota from PD patients not only altered the composition of the gut microbiota but also influenced the fecal metabolic profile of the recipient mice.

CONCLUSION

The fecal microbiota from PD patients intensifies inflammation and neurodegeneration in A53T mice. Our findings demonstrate that imbalance and dysfunction in the gut microbiome play significant roles in the development and advancement of PD.

Biomarkers of Parkinson's Disease: From Basic Research to Clinical Practice

Parkinson's disease (PD) is a common neurodegenerative disease characterized pathologically by dopaminergic neuron loss and the formation of Lewy bodies, which are enriched with aggregated α-synuclein (α-syn). PD currently has no cure, but therapeutic strategies are available to alleviate symptoms. Early diagnosis can greatly improve therapeutic interventions, but the clinical diagnosis of PD remains challenging and depends mainly on clinical features and imaging tests. Efficient and specific biomarkers are crucial for the diagnosis, monitoring, and evaluation of PD. Here, we reviewed the biomarkers of PD in different tissues and biofluids, along with the current clinical biochemical detection methods. We found that the sensitivity and specificity of single biomarkers are limited, and selecting appropriate indicators for combined detection can improve the diagnostic accuracy of PD.

Pyroptosis-mediator GSDMD promotes Parkinson's disease pathology via microglial activation and dopaminergic neuronal death

GSDMD-mediated pyroptosis occurs in the nigrostriatal pathway in Parkinson's disease animals, yet the role of GSDMD in neuroinflammation and death of dopaminergic neurons in Parkinson's disease remains elusive. Here, our in vivo and in vitro studies demonstrated that GSDMD, as a pyroptosis executor, contributed to glial reaction and death of dopaminergic neurons across different Parkinson's disease models. The ablation of the Gsdmd attenuated Parkinson's disease damage by reducing dopaminergic neuronal death, microglial activation, and detrimental transformation. Disulfiram, an inhibitor blocking GSDMD pore formation, efficiently curtailed pyroptosis, thereby lessening the pathology of Parkinson's disease. Additionally, a modification in GSDMD was identified in the blood of Parkinson's disease patients in contrast to healthy subjects. Therefore, the detected alteration in GSDMD within the blood of Parkinson's disease patients and the protective impact of disulfiram could be promising for the diagnostic and therapeutic approaches against Parkinson's disease.

Potential convergence of olfactory dysfunction in Parkinson's disease and COVID-19: The role of neuroinflammation

Parkinson's disease (PD) is a prevalent neurodegenerative disorder that affects 7-10 million individuals worldwide. A common early symptom of PD is olfactory dysfunction (OD), and more than 90% of PD patients suffer from OD. Recent studies have highlighted a high incidence of OD in patients with SARS-CoV-2 infection. This review investigates the potential convergence of OD in PD and COVID-19, particularly focusing on the mechanisms by which neuroinflammation contributes to OD and neurological events. Starting from our fundamental understanding of the olfactory bulb, we summarize the clinical features of OD and pathological features of the olfactory bulb from clinical cases and autopsy reports in PD patients. We then examine SARS-CoV-2-induced olfactory bulb neuropathology and OD and emphasize the SARS-CoV-2-induced neuroinflammatory cascades potentially leading to PD manifestations. By activating microglia and astrocytes, as well as facilitating the aggregation of α-synuclein, SARS-CoV-2 could contribute to the onset or exacerbation of PD. We also discuss the possible contributions of NF-κB, the NLRP3 inflammasome, and the JAK/STAT, p38 MAPK, TLR4, IL-6/JAK2/STAT3 and cGAS-STING signaling pathways. Although olfactory dysfunction in patients with COVID-19 may be reversible, it is challenging to restore OD in patients with PD. With the emergence of new SARS-CoV-2 variants and the recurrence of infections, we call for continued attention to the intersection between PD and SARS-CoV-2 infection, especially from the perspective of OD.

Lack of genetic evidence for NLRP3-inflammasome involvement in Parkinson's disease pathogenesis

Activation of the NLRP3-inflammasome has been implicated in Parkinson's disease based on in vitro and in vivo studies. Clinical trials targeting the NLRP3-inflammasome in Parkinson's disease are ongoing. However, the evidence supporting NLRP3's involvement in Parkinson's disease from human genetics data is limited. In this study, we conducted analyses of common and rare variants in NLRP3-inflammasome related genes in Parkinson's disease cohorts. We performed pathway-specific analyses using polygenic risk scores and studied potential causal associations using Mendelian randomization with the NLRP3 components and the cytokines IL-1β and IL-18. Our findings showed no associations of common or rare variants, nor of the pathway polygenic risk score with Parkinson's disease. Mendelian randomization suggests that altering the expression of the NLRP3-inflammasome, IL-1β or IL-18, does not affect Parkinson's disease risk or progression. Therefore, our results do not support a role for the NLRP3-inflammasome in Parkinson's disease pathogenesis or as a target for drug development.

Research on the signaling pathways related to the intervention of traditional Chinese medicine in Parkinson's disease:A literature review

ETHNOPHARMACOLOGICAL RELEVANCE

Parkinson's disease (PD) is the most common progressive neurodegenerative disorder affecting more than 10 million people worldwide and is characterized by the progressive loss of Daergic (DA) neurons in the substantia nigra pars compacta. It has been reported that signaling pathways play a crucial role in the pathogenesis of PD, while the active ingredients of traditional Chinese medicine (TCM) have been found to possess a protective effect against PD. TCM has demonstrated significant potential in mitigating oxidative stress (OS), neuroinflammation, and apoptosis of DA neurons via the regulation of signaling pathways associated with PD.

AIM OF THE REVIEW

This study discussed and analyzed the signaling pathways involved in the occurrence and development of PD and the mechanism of active ingredients of TCM regulating PD via signaling pathways, with the aim of providing a basis for the development and clinical application of therapeutic strategies for TCM in PD.

MATERIALS AND METHODS

With "Parkinson's disease", "Idiopathic Parkinson's Disease", "Lewy Body Parkinson's Disease", "Parkinson's Disease, Idiopathic", "Parkinson Disease, Idiopathic", "Parkinson's disorders", "Parkinsonism syndrome", "Traditional Chinese medicine", "Chinese herbal medicine", "active ingredients", "medicinal plants" as the main keywords, PubMed, Web of Science and other online search engines were used for literature retrieval.

RESULTS

PD exhibits a close association with various signaling pathways, including but not limited to MAPKs, NF-κB, PI3K/Akt, Nrf2/ARE, Wnt/β-catenin, TLR/TRIF, NLRP3, Notch. The therapeutic potential of TCM lies in its ability to regulate these signaling pathways. In addition, the active ingredients of TCM have shown significant effects in improving OS, neuroinflammation, and DA neuron apoptosis in PD.

CONCLUSION

The active ingredients of TCM have unique advantages in regulating PD-related signaling pathways. It is suggested to combine network pharmacology and bioinformatics to study the specific targets of TCM. This not only provides a new way for the prevention and treatment of PD with the active ingredients of TCM, but also provides a scientific basis for the selection and development of TCM preparations.

Mitochondrial dysfunction in chronic neuroinflammatory diseases (Review)

Chronic neuroinflammation serves a key role in the onset and progression of neurodegenerative disorders. Mitochondria serve as central regulators of neuroinflammation. In addition to providing energy to cells, mitochondria also participate in the immunoinflammatory response of neurodegenerative disorders including Alzheimer's disease, Parkinson's disease, multiple sclerosis and epilepsy, by regulating processes such as cell death and inflammasome activation. Under inflammatory conditions, mitochondrial oxidative stress, epigenetics, mitochondrial dynamics and calcium homeostasis imbalance may serve as underlying regulatory mechanisms for these diseases. Therefore, investigating mechanisms related to mitochondrial dysfunction may result in therapeutic strategies against chronic neuroinflammation and neurodegeneration. The present review summarizes the mechanisms of mitochondria in chronic neuroinflammatory diseases and the current treatment approaches that target mitochondrial dysfunction in these diseases.

Innate immune activation in neurodegenerative diseases

Activation of the innate immune system following pattern recognition receptor binding has emerged as one of the major pathogenic mechanisms in neurodegenerative disease. Experimental, epidemiological, pathological, and genetic evidence underscores the meaning of innate immune activation during the prodromal as well as clinical phases of several neurodegenerative disorders including Alzheimer's disease, Parkinson's disease, amyotrophic lateral sclerosis, and frontotemporal dementia. Importantly, innate immune activation and the subsequent release of inflammatory mediators contribute mechanistically to other hallmarks of neurodegenerative diseases such as aberrant proteostatis, pathological protein aggregation, cytoskeleton abnormalities, altered energy homeostasis, RNA and DNA defects, and synaptic and network disbalance and ultimately to the induction of neuronal cell death. In this review, we discuss common mechanisms of innate immune activation in neurodegeneration, with particular emphasis on the pattern recognition receptors (PRRs) and other receptors involved in the detection of damage-associated molecular patterns (DAMPs).

An adapted protocol to derive microglia from stem cells and its application in the study of CSF1R-related disorders

BACKGROUND

Induced pluripotent stem cell-derived microglia (iMGL) represent an excellent tool in studying microglial function in health and disease. Yet, since differentiation and survival of iMGL are highly reliant on colony-stimulating factor 1 receptor (CSF1R) signaling, it is difficult to use iMGL to study microglial dysfunction associated with pathogenic defects in CSF1R.

METHODS

Serial modifications to an existing iMGL protocol were made, including but not limited to changes in growth factor combination to drive microglial differentiation, until successful derivation of microglia-like cells from an adult-onset leukoencephalopathy with axonal spheroids and pigmented glia (ALSP) patient carrying a c.2350G > A (p.V784M) CSF1R variant. Using healthy control lines, the quality of the new iMGL protocol was validated through cell yield assessment, measurement of microglia marker expression, transcriptomic comparison to primary microglia, and evaluation of inflammatory and phagocytic activities. Similarly, molecular and functional characterization of the ALSP patient-derived iMGL was carried out in comparison to healthy control iMGL.

RESULTS

The newly devised protocol allowed the generation of iMGL with enhanced transcriptomic similarity to cultured primary human microglia and with higher scavenging and inflammatory competence at ~ threefold greater yield compared to the original protocol. Using this protocol, decreased CSF1R autophosphorylation and cell surface expression was observed in iMGL derived from the ALSP patient compared to those derived from healthy controls. Additionally, ALSP patient-derived iMGL presented a migratory defect accompanying a temporal reduction in purinergic receptor P2Y12 (P2RY12) expression, a heightened capacity to internalize myelin, as well as heightened inflammatory response to Pam3CSK4. Poor P2RY12 expression was confirmed to be a consequence of CSF1R haploinsufficiency, as this feature was also observed following CSF1R knockdown or inhibition in mature control iMGL, and in CSF1RWT/KO and CSF1RWT/E633K iMGL compared to their respective isogenic controls.

CONCLUSIONS

We optimized a pre-existing iMGL protocol, generating a powerful tool to study microglial involvement in human neurological diseases. Using the optimized protocol, we have generated for the first time iMGL from an ALSP patient carrying a pathogenic CSF1R variant, with preliminary characterization pointing toward functional alterations in migratory, phagocytic and inflammatory activities.

Locus coeruleus injury modulates ventral midbrain neuroinflammation during DSS-induced colitis

Parkinson's disease (PD) is characterized by a decades-long prodrome, consisting of a collection of non-motor symptoms that emerges prior to the motor manifestation of the disease. Of these non-motor symptoms, gastrointestinal dysfunction and deficits attributed to central norepinephrine (NE) loss, including mood changes and sleep disturbances, are frequent in the PD population and emerge early in the disease. Evidence is mounting that injury and inflammation in the gut and locus coeruleus (LC), respectively, underlie these symptoms, and the injury of these systems is central to the progression of PD. In this study, we generate a novel two-hit mouse model that captures both features, using dextran sulfate sodium (DSS) to induce gut inflammation and N-(2-chloroethyl)-N-ethyl-2-bromobenzylamine (DSP-4) to lesion the LC. We first confirmed the specificity of DSP-4 for central NE using neurochemical methods and fluorescence light-sheet microscopy of cleared tissue, and established that DSS-induced outcomes in the periphery, including weight loss, gross indices of gut injury and systemic inflammation, the loss of tight junction proteins in the colonic epithelium, and markers of colonic inflammation, were unaffected with DSP-4 pre-administration. We then measured alterations in neuroimmune gene expression in the ventral midbrain in response to DSS treatment alone as well as the extent to which prior LC injury modified this response. In this two-hit model we observed that DSS-induced colitis activates the expression of key cytokines and chemokines in the ventral midbrain only in the presence of LC injury and the typical DSS-associated neuroimmune is blunted by pre-LC lesioning with DSP-4. In all, this study supports the growing appreciation for the LC as neuroprotective against inflammation-induced brain injury and draws attention to the potential for NEergic interventions to exert disease-modifying effects under conditions where peripheral inflammation may compromise ventral midbrain dopaminergic neurons and increase the risk for development of PD.

New Insights on NLRP3 Inflammasome: Mechanisms of Activation, Inhibition, and Epigenetic Regulation

Inflammasomes are important modulators of inflammation. Dysregulation of inflammasomes can enhance vulnerability to conditions such as neurodegenerative diseases, autoinflammatory diseases, and metabolic disorders. Among various inflammasomes, Nucleotide-binding oligomerization domain leucine-rich repeat and pyrin domain-containing protein 3 (NLRP3) is the best-characterized inflammasome related to inflammatory and neurodegenerative diseases. NLRP3 is an intracellular sensor that recognizes pathogen-associated molecular patterns and damage-associated patterns resulting in the assembly and activation of NLRP3 inflammasome. The NLRP3 inflammasome includes sensor NLRP3, adaptor apoptosis-associated speck-like protein (ASC), and effector cysteine protease procaspase-1 that plays an imperative role in caspase-1 stimulation which further initiates a secondary inflammatory response. Regulation of NLRP3 inflammasome ameliorates NLRP3-mediated diseases. Much effort has been invested in studying the activation, and exploration of specific inhibitors and epigenetic mechanisms controlling NLRP3 inflammasome. This review gives an overview of the established NLRP3 inflammasome assembly, its brief molecular mechanistic activations as well as a current update on specific and non-specific NLRP3 inhibitors that could be used in NLRP3-mediated diseases. We also focused on the recently discovered epigenetic mechanisms mediated by DNA methylation, histone alterations, and microRNAs in regulating the activation and expression of NLRP3 inflammasome, which has resulted in a novel method of gaining insight into the mechanisms that modulate NLRP3 inflammasome activity and introducing potential therapeutic strategies for CNS disorders.

Mitochondrial homeostasis regulation: A promising therapeutic target for Parkinson's disease

Parkinson's disease (PD) is a neurodegenerative disease characterized by progressive loss of dopaminergic (DA) neurons in the substantia nigra pars compacta (SNc) and the presence of Lewy bodies (LBs) or Lewy neurites (LNs) which consist of α-synuclein (α-syn) and a complex mix of other biomolecules. Mitochondrial dysfunction is widely believed to play an essential role in the pathogenesis of PD and other related neurodegenerative diseases. But mitochondrial dysfunction is subject to complex genetic regulation. There is increasing evidence that PD-related genes directly or indirectly affect mitochondrial integrity. Therefore, targeted regulation of mitochondrial function has great clinical application prospects in the treatment of PD. However, lots of PD drugs targeting mitochondria have been developed but their clinical therapeutic effects are not ideal. This review aims to reveal the role of mitochondrial dysfunction in the pathogenesis of neurodegenerative diseases based on the mitochondrial structure and function, which may highlight potential interventions and therapeutic targets for the development of PD drugs to recover mitochondrial dysfunction in neurodegenerative diseases.

Locus coeruleus injury modulates ventral midbrain neuroinflammation during DSS-induced colitis

Parkinson's disease (PD) is characterized by a decades-long prodrome, consisting of a collection of non-motor symptoms that emerges prior to the motor manifestation of the disease. Of these non-motor symptoms, gastrointestinal dysfunction and deficits attributed to central norepinephrine (NE) loss, including mood changes and sleep disturbances, are frequent in the PD population and emerge early in the disease. Evidence is mounting that injury and inflammation in the gut and locus coeruleus (LC), respectively, underlie these symptoms, and the injury of these systems is central to the progression of PD. In this study, we generate a novel two-hit mouse model that captures both features, using dextran sulfate sodium (DSS) to induce gut inflammation and N-(2-chloroethyl)-N-ethyl-2-bromobenzylamine (DSP-4) to lesion the LC. We first confirmed the specificity of DSP-4 for central NE using neurochemical methods and fluorescence light-sheet microscopy of cleared tissue, and established that DSS-induced outcomes in the periphery, including weight loss, gross indices of gut injury and systemic inflammation, the loss of tight junction proteins in the colonic epithelium, and markers of colonic inflammation, were unaffected with DSP-4 pre-administration. We then measured alterations in neuroimmune gene expression in the ventral midbrain in response to DSS treatment alone as well as the extent to which prior LC injury modified this response. In this two-hit model we observed that DSS-induced colitis activates the expression of key cytokines and chemokines in the ventral midbrain only in the presence of LC injury and the typical DSS-associated neuroimmune is blunted by pre-LC lesioning with DSP-4. In all, this study supports the growing appreciation for the LC as neuroprotective against inflammation-induced brain injury and draws attention to the potential for NEergic interventions to exert disease-modifying effects under conditions where peripheral inflammation may compromise ventral midbrain dopaminergic neurons and increase the risk for development of PD.

Inflammasomes in neurological disorders - mechanisms and therapeutic potential

Inflammasomes are molecular scaffolds that are activated by damage-associated and pathogen-associated molecular patterns and form a key element of innate immune responses. Consequently, the involvement of inflammasomes in several diseases that are characterized by inflammatory processes, such as multiple sclerosis, is widely appreciated. However, many other neurological conditions, including Alzheimer disease, Parkinson disease, amyotrophic lateral sclerosis, stroke, epilepsy, traumatic brain injury, sepsis-associated encephalopathy and neurological sequelae of COVID-19, all involve persistent inflammation in the brain, and increasing evidence suggests that inflammasome activation contributes to disease progression in these conditions. Understanding the biology and mechanisms of inflammasome activation is, therefore, crucial for the development of inflammasome-targeted therapies for neurological conditions. In this Review, we present the current evidence for and understanding of inflammasome activation in neurological diseases and discuss current and potential interventional strategies that target inflammasome activation to mitigate its pathological consequences.

Molecular crosstalk between circadian clock and NLRP3 inflammasome signaling in Parkinson's disease

Parkinson's disease (PD) is one of the most common neurodegenerative diseases. Research has recently found that both animal models and patients with PD have circadian dysfunction, accompanied by abnormal expression of circadian genes and proteins, which implies that the circadian clock plays a crucial role in PD etiopathogenesis. In addition, a strong relationship between NLRP3 inflammasome signaling and PD has been observed. Meanwhile, the activation of the NLRP3 inflammasome is highly relevant to dysfunctions of the molecular clock. Therefore, alleviating the neuroinflammation caused by NLRP3 inflammasome signaling by adjusting the abnormal molecular clock may be a potential strategy for preventing and treating PD. In this article, we have reviewed the potential or direct relationship between abnormalities of the circadian clock and NLRP3 inflammasome signaling in PD.

Ciita Regulates Local and Systemic Immune Responses in a Combined rAAV-α-synuclein and Preformed Fibril-Induced Rat Model for Parkinson's Disease

Background

Parkinson's disease (PD) is characterized by alpha-synuclein (α-Syn) pathology, neurodegeneration and neuroinflammation. Human leukocyte antigen (HLA) variants associated with PD and α-Syn specific CD4+ T lymphocytes in PD patients highlight the importance of antigen presentation in PD etiology. The class II transactivator (CIITA) regulates major histocompatibility complex class II (MHCII) expression. Reduced Ciita levels significantly increase α-Syn pathology, nigrostriatal neurodegeneration and behavioral deficits in α-Syn-induced rat PD models.

Objective

Characterize immune profiles associated with enhanced PD-like pathology observed in rats expressing lower Ciita levels (DA.VRA4) compared to the background strain (DA).

Methods

To model PD, we combined rAAV-mediated α-Syn overexpression in the substantia nigra with striatal injection of α-Syn preformed fibrils. Immune profiles in brain and blood were analyzed by flow cytometry and multiplexed ELISA in naïve rats, 4- and 8 weeks post rAAV injection.

Results

Flow cytometry showed Ciita-dependent regulation of MHCII on microglia, brain macrophages and circulating myeloid cells. The MHCII-dependent microglial response was highest at 4 weeks post rAAV injection, whereas the MHCII levels in circulating myeloid cells was highest at 8 weeks. There was no major infiltration of macrophages or T lymphocytes into the CNS in response to α-Syn and only subtle Ciita- and/or α-Syn-dependent changes in the T lymphocyte compartment. Lower Ciita levels were consistently associated with higher TNF levels in serum.

Conclusions

Ciita regulates susceptibility to PD-like pathology through minor but detectable changes in resident and peripheral immune cells and TNF levels, indicating that mild immunomodulatory therapies could have therapeutic effects in PD.

Clinical Trial Highlights: Anti-Inflammatory and Immunomodulatory Agents

Inflammation and immune dysregulation have been linked to the pathogenesis and progression of Parkinson's disease (PD), and represent an attractive target for therapeutic intervention, given the potential for repurposing of existing anti-inflammatory and immunomodulatory agents. Despite the fact that initial studies of drugs with secondary anti-inflammatory effects did not yield positive results, agents specifically targeting immune and inflammatory pathways may hold more promise. This article will briefly review the evidence base for targeting the immune system and neuroinflammation in PD, and discuss in detail the recently completed and currently active trials of primary anti-inflammatory/immunomodulatory drugs in PD.

Role of Brain Liver X Receptor in Parkinson's Disease: Hidden Treasure and Emerging Opportunities

Parkinson's disease (PD) is a neurodegenerative disease due to the degeneration of dopaminergic neurons (DNs) in the substantia nigra (SN). The liver X receptor (LXR) is involved in different neurodegenerative diseases. Therefore, the objective of the present review was to clarify the possible role of LXR in PD neuropathology. LXRs are the most common nuclear receptors of transcription factors that regulate cholesterol metabolism and have pleiotropic effects, including anti-inflammatory effects and reducing intracellular cholesterol accumulation. LXRs are highly expressed in the adult brain and act as endogenous sensors for intracellular cholesterol. LXRs have neuroprotective effects against the development of neuroinflammation in different neurodegenerative diseases by inhibiting the expression of pro-inflammatory cytokines. LXRs play an essential role in mitigating PD neuropathology by reducing the expression of inflammatory signaling pathways, neuroinflammation, oxidative stress, mitochondrial dysfunction, and enhancement of BDNF signaling.In conclusion, LXRs, through regulating brain cholesterol homeostasis, may be effectual in PD. Also, inhibition of node-like receptor pyrin 3 (NLRP3) inflammasome and nuclear factor kappa B (NF-κB) by LXRs could effectively prevent neuroinflammation in PD. Taken together, LXRs play a crucial role in PD neuropathology by inhibiting neuroinflammation and associated degeneration of DNs.