MPTP-driven NLRP3 inflammasome activation in microglia plays a central role in dopaminergic neurodegeneration

Hyperglycemia enhances brain susceptibility to lipopolysaccharide-induced neuroinflammation via astrocyte reprogramming

Hyperglycemia has been shown to modulate the immune response of peripheral immune cells and organs, but the impact of hyperglycemia on neuroinflammation within the brain remains elusive. In the present study, we provide evidences that streptozotocin (STZ)-induced hyperglycemic condition in mice drives a phenotypic switch of brain astrocytes to a proinflammatory state, and increases brain vulnerability to mild peripheral inflammation. In particular, we found that hyperglycemia led to a significant increase in the astrocyte proliferation as determined by flow cytometric and immunohistochemical analyses of mouse brain. The increased astrocyte proliferation by hyperglycemia was reduced by Glut1 inhibitor BAY-876. Transcriptomic analysis of isolated astrocytes from Aldh1l1CreERT2;tdTomato mice revealed that peripheral STZ injection induced astrocyte reprogramming into proliferative, and proinflammatory phenotype. Additionally, STZ-induced hyperglycemic condition significantly enhanced the infiltration of circulating myeloid cells into the brain and the disruption of blood-brain barrier in response to mild lipopolysaccharide (LPS) administration. Systemic hyperglycemia did not alter the intensity and sensitivity of peripheral inflammation in mice to LPS challenge, but increased the inflammatory potential of brain microglia. In line with findings from mouse experiments, a high-glucose environment intensified the LPS-triggered production of proinflammatory molecules in primary astrocyte cultures. Furthermore, hyperglycemic mice exhibited a significant impairment in cognitive function after mild LPS administration compared to normoglycemic mice as determined by novel object recognition and Y-maze tasks. Taken together, these results demonstrate that hyperglycemia directly induces astrocyte reprogramming towards a proliferative and proinflammatory phenotype, which potentiates mild LPS-triggered inflammation within brain parenchymal regions.

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.

Electroacupuncture blocked motor dysfunction and gut barrier damage by modulating intestinal NLRP3 inflammasome in MPTP-induced Parkinson's disease mice

Parkinson's disease (PD) is a neurodegenerative disorder commonly accompanied by gut dysfunction. EA has shown anti-inflammatory and neuroprotective effects. Here, we aim to explore whether EA can treat Parkinson's disease by restoring the intestinal barrier and modulating NLRP3 inflammasome. We applied 1-Methyl-4-phenyl-1,2,3,6-tetrahydropyridine (MPTP) to establish a PD mouse model and EA at the GV16, LR3, and ST36 for 12 consecutive days. The open-field test results indicated that EA alleviated depression and behavioral defects, upregulated the expressions of tyrosine hydroxylase (TH) and brain-derived neurotrophic factor (BDNF), and blocked the accumulation of α-synuclein (α-syn) in the midbrain. Moreover, EA blocked the damage to intestinal tissues of PD mice, indicative of suppressed NLRP3 inflammasome activation and increased gut barrier integrity. Notably, the antibiotic-treated mouse experiment validated that the gut microbiota was critical in alleviating PD dyskinesia and intestinal inflammation by EA. In conclusion, this study suggested that EA exhibited a protective effect against MPTP-induced PD by alleviating behavioral defects, reversing the block of motor dysfunction, and improving the gut barrier by modulating intestinal NLRP3 inflammasome. Above all, this study could provide novel insights into the pathogenesis and therapy of PD.

The interplay between mitochondrial dysfunction and NLRP3 inflammasome in multiple sclerosis: Therapeutic implications and animal model studies

Multiple sclerosis (MS) is a complex autoimmune disorder that impacts the central nervous system (CNS), resulting in inflammation, demyelination, and neurodegeneration. The NOD-like receptor (NLR) family pyrin domain-containing 3 (NLRP3) inflammasome, a multiprotein complex of the innate immune system, serves an essential role in the pathogenesis of MS by regulating the production of pro-inflammatory cytokines (IL-1β & IL-18) and the induction of pyroptotic cell death. Mitochondrial dysfunction is one of the main potential factors that can trigger NLRP3 inflammasome activation and lead to inflammation and axonal damage in MS. This highlights the importance of understanding how mitochondrial dynamics modulate NLRP3 inflammasome activity and contribute to the inflammatory and neurodegenerative features of MS. The lack of a comprehensive understanding of the pathogenesis of MS and the urge for the introduction of new therapeutic strategies led us to review the therapeutic potential of targeting the interplay between mitochondrial dysfunction and the NLRP3 inflammasome in MS. This paper also evaluates the natural and synthetic compounds that can improve mitochondrial function and/or inhibit the NLRP3 inflammasome, thereby providing neuroprotection. Moreover, it summarizes the evidence from animal models of MS that demonstrate the beneficial effects of these compounds on reducing inflammation, demyelination, and neurodegeneration. Finally, this review advocates for a deeper investigation into the molecular crosstalk between mitochondrial dynamics and the NLRP3 inflammasome as a means to refine therapeutic targets for MS.

Asiaticoside exerts neuroprotection through targeting NLRP3 inflammasome activation

BACKGROUND

Parkinson's disease (PD), a neurodegenerative disorder, is characterized by motor symptoms due to the progressive loss of dopaminergic neurons in the substantia nigra (SN) and striatum (STR), alongside neuroinflammation. Asiaticoside (AS), a primary active component with anti-inflammatory and neuroprotective properties, is derived from Centella asiatica. However, the precise mechanisms through which AS influences PD associated with inflammation are not yet fully understood.

PURPOSE

This study aimed to explore the protective mechanism of AS in PD.

METHODS

Targets associated with AS and PD were identified from the Swiss Target Prediction, Similarity Ensemble Approach, PharmMapper, and GeneCards database. A protein-protein interaction (PPI) network was constructed to identify potential therapeutic targets. Concurrently, GO and KEGG analyses were performed to predict potential signaling pathways. To validate these mechanisms, the effects of AS on 1-Methyl-4-phenyl-1,2,3,6-tetrahydropyridine (MPTP)-induced PD in mice were investigated. Furthermore, neuroinflammation and the activation of the NLRP3 inflammasome were assessed to confirm the anti-inflammatory properties of AS. In vitro experiments in BV2 cells were then performed to investigate the mechanisms of AS in PD. Moreover, CETSA, molecular docking, and molecular dynamics simulations (MDs) were performed for further validation.

RESULTS

Network pharmacology analysis identified 17 potential targets affected by AS in PD. GO and KEGG analyses suggested the biological roles of these targets, demonstrating that AS interacts with 149 pathways in PD. Notably, the NOD-like receptor signaling pathway was identified as a key pathway mediating AS's effect on PD. In vivo studies demonstrated that AS alleviated motor dysfunction and reduced the loss of dopaminergic neurons in MPTP-induced PD mice. In vitro experiments demonstrated that AS substantially decreased IL-1β release in BV2 cells, attributing this to the modulation of the NLRP3 signaling pathway. CETSA and molecular docking studies indicated that AS forms a stable complex with NLRP3. MDs suggested that ARG578 played an important role in the formation of the complex.

CONCLUSION

In this study, we first predicted that the potential target and pathway of AS's effect on PD could be NLRP3 protein and NOD-like receptor signaling pathway by network pharmacology analysis. Further, we demonstrated that AS could alleviate symptoms of PD induced by MPTP through its interaction with the NLRP3 protein for the first time by in vivo and in vitro experiments. By binding to NLRP3, AS effectively inhibits the assembly and activation of the inflammasome. These findings suggest that AS is a promising inhibitor for PD driven by NLRP3 overactivation.

TREM2 Deficiency Aggravates NLRP3 Inflammasome Activation and Pyroptosis in MPTP-Induced Parkinson's Disease Mice and LPS-Induced BV2 Cells

Microglia-mediated neuroinflammation plays a crucial role in the pathogenesis of Parkinson's disease (PD). Triggering receptor expressed on myeloid cells 2 (TREM2) confers strong neuroprotective effects in PD by regulating the phenotype of microglia. Recent studies suggest that TREM2 regulates high glucose-induced microglial inflammation through the NLRP3 signaling pathway. This study aimed to investigate the effect of TREM2 on NLRP3 inflammasome activation and neuroinflammation in PD. Mice were injected with AAV-TREM2-shRNA into both sides of the substantia nigra using a stereotactic injection method, followed by intraperitoneal injection of MPTP to establish chronic PD mouse model. Behavioral assessments including the pole test and rotarod test were conducted to evaluate the effects of TREM2 deficiency on MPTP-induced motor dysfunction. Immunohistochemistry of TREM2 and tyrosine hydroxylase (TH), immunohistochemistry and immunofluorescence Iba1, Western blot of NLRP3 inflammasome and its downstream inflammatory factors IL-1β and IL-18, and the key pyroptosis factors GSDMD and GSDMD-N were performed to explore the effect of TREM2 on NLRP3 inflammasome and neuroinflammation. In an in vitro experiment, lentivirus was used to interfere with the expression of TREM2 in BV2 microglia, and then lipopolysaccharide (LPS) and adenopterin nucleoside triphosphate (ATP) were used to stimulate inflammation to construct a cellular inflammation model. The expression differences of NLRP3 inflammasome and its components were detected by qPCR and Western blot. In vivo, TREM2 knockdown aggravated the loss of dopaminergic neuron and the decline of motor function. After TREM2 knockdown, the number of activated microglia was significantly increased, and the expression of cleaved caspase-1, NLRP3 inflammasome, IL-1β, GSDMD, and GSDMD-N was increased. In vitro, TREM2 knockdown aggravated the inflammatory response of BV2 cells stimulated by LPS and promoted the activation of NLRP3 inflammasome through the NF-κB pathway. In addition, TREM2 knockdown also promoted the expression of TLR4/MyD88, an upstream factor of the NF-κB pathway. Our vivo and vitro data showed that TREM2 knockdown promoted NLRP3 inflammasome activation and downstream inflammatory response, promoted pyroptosis, and aggravated dopaminergic neuron loss. TREM2 acts as an anti-inflammatory in PD through the TLR4/MyD88/NF-κB pathway, which extends previous findings and supports the notion that TREM2 ameliorates neuroinflammation in PD.

Causal role of myeloid cells in Parkinson's disease: Mendelian randomization study

BACKGROUND

Previous studies have observed elevated myeloid cells in the peripheral blood of patients with Parkinson's disease (PD), but the causal relationship between them remains to be elucidated. We investigated whether there is a causal relationship between different subtypes of peripheral blood myeloid cells and PD using Mendelian randomization (MR) combined with bioinformatics analysis. Exploring the etiology of PD from the perspective of genetics can remove confounding factors and provide a more reliable theoretical basis for elucidating the pathogenesis of PD.

METHODS

Comprehensive two-sample MR analysis and sensitivity analyses were conducted to explore the causal associations between 64 myeloid cell signatures and PD risk. The Venn diagram and protein-protein interaction network analysis of instrumental variables (IV) corresponding genes were used to further investigate the potential mechanism of myeloid cells influencing the pathogenesis of PD.

RESULTS

We investigated the impact of four immunophenotypes on the risk of PD, including Im MDSC% CD33dim HLA DR- CD66b- (relative count), CD33dim HLA DR+ CD11b+% CD33dim HLA DR+ (relative count), and CD11b on Mo MDSC (MFI) and CD11b on CD33br HLA DR+ CD14dim (MFI), while an immunophenotype's protective effect on PD was observed CD45 on Im MDSC (MFI). The results of bioinformatics analysis showed that CD33, NTRK2, PLD2, GRIK2 and RELN had protein interactions with the risk genes of PD.

CONCLUSIONS

Our study has demonstrated a close genetic correlation between different subtypes of myeloid cells and PD, providing guidance for early identification and immunotherapeutic development in patients with PD.

Dose-Ranging Effects of the Intracerebral Administration of Atsttrin in Experimental Model of Parkinson's Disease Induced by 1-Methyl-4-phenyl-1,2,3,6-tetrahydropyridine (MPTP) in Mice

Parkinson's disease is one of the most common neurodegenerative disorders characterized by a multitude of motor and non-motor clinical symptoms resulting from the progressive and long-lasting abnormal loss of nigrostriatal dopaminergic neurons. Currently, the available treatments for patients with Parkinson's disease are limited and exert only symptomatic effects, without adequate signs of delaying or stopping the progression of the disease. Atsttrin constitutes the bioengineered protein which ultrastructure is based on the polypeptide chain frame of the progranulin (PGRN), which exerts anti-inflammatory effects through the inhibition of TNFα. The conducted preclinical studies suggest that the therapeutic implementation of Atsttrin may be potentially effective in the treatment of neurodegenerative diseases that are associated with the occurrence of neuroinflammatory processes. The aim of the proposed study was to investigate the effect of direct bilateral intracerebral administration of Atsttrin using stereotactic methods in the preclinical C57BL/6 mouse model of Parkinson's disease inducted by 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine (MPTP) intoxication. The analysis of the dose dependency effects of the increasing doses of Atsttrin has covered a number of parameters and markers regarding neurodegenerative processes and inflammatory responses including IL-1α, TNFα, IL-6, TH, and TG2 mRNA expressions. Accordingly, the evaluation of the changes in the neurochemical profile included DA, DOPAC, 3-MT, HVA, NA, MHPG, 5-HT, and 5-HIAA concentration levels. The intracerebral administration of Atsttrin into the striatum effectively attenuated the neuroinflammatory reaction in evaluated neuroanatomical structures. Furthermore, the partial restoration of monoamine content and its metabolic turnover were observed. In this case, taking into account the previously described pharmacokinetic profile and extrapolated bioavailability as well as the stability characteristics of Atsttrin, an attempt was made to describe as precisely as possible the quantitative and qualitative effects of increasing doses of the compound within the brain tissue microenvironment in the presented preclinical model of the disease. Collectively, this findings demonstrated that the intracerebral administration of Atsttrin may represent a potential novel therapeutic method for the treatment of Parkinson's disease.

V-set and immunoglobulin domain containing 4 inhibits oxidative stress, mitochondrial dysfunction, and inflammation to attenuate Parkinson's disease progression by activating the JAK2/STAT3 pathway

OBJECTIVE

V-set and immunoglobulin domain containing 4 (VSIG4) inhibits neurological dysfunction, microglial M1 polarization, and inflammation to participate in the progression of neurological disorders, but evidence regarding Parkinson's disease (PD) is scarce. The present study intended to investigate the engagement of VSIG4 in PD progression, and the potential mechanism.

METHODS

BV-2 cells were treated with 1-Methyl-4-phenylpyridinium (MPP+) to establish PD model. MPP+ treated BV-2 cells were infected with VSIG4 overexpression adenovirus-associated virus (AAV) (oeVSIG4) and negative control AAV (oeNC), and AZD1480 (JAK2 inhibitor) was added to these cells.

RESULTS

MPP+ reduced VSIG4 mRNA (P < 0.05) and protein (P < 0.05) in BV-2 cells. Interestingly, VSIG4 reduced malondialdehyde (P < 0.01), reactive oxygen species (P < 0.01), NOD-like receptor family pyrin domain containing 3 (P < 0.05), cleaved-caspase1 (P < 0.05), tumor necrosis factor-α (P < 0.05), and interleukin-1β (P < 0.05), but increased glutathione (P < 0.05), mitochondrial membrane potential (P < 0.05), phosphorylation (p)-JAK2 (P < 0.05), and p-STAT3 (P < 0.01) in MPP+ treated BV-2 cells, which indicated that VSIG4 inhibited oxidative stress, mitochondrial dysfunction, and inflammation, as well as activated the JAK2/STAT3 pathway in PD model. Moreover, AZD1480 inhibited the JAK2/STAT3 pathway and aggravated oxidative stress, mitochondrial dysfunction, and inflammation in PD model (all P < 0.05). Importantly, AZD1480 attenuated the influence of VSIG4 on oxidative stress, mitochondrial dysfunction, inflammation, and the JAK2/STAT3 pathway in PD model (all P < 0.05).

CONCLUSION

VSIG4 suppresses oxidative stress, mitochondrial dysfunction, and inflammation by activating the JAK2/STAT3 pathway, which may be helpful in attenuating PD progression.

Role of NLRP3 in Parkinson's disease: Specific activation especially in dopaminergic neurons

Parkinson's disease (PD) is a neurodegenerative disorder with motor symptoms like bradykinesia, tremors, and balance issues. The pathology is recognized by progressively degenerative nigrostriatal dopaminergic neurons (DANs) loss. Its exact pathogenesis is unclear. Numerous studies have shown that nucleotide-binding oligomerization domain-like receptor protein 3 (NLRP3) contributes to the pathogenesis of PD. Previous studies have demonstrated that the over-activation of NLRP3 inflammasome in microglia indirectly leads to the loss of DANs, which can worsen PD. In recent years, autopsy analyses of PD patients and studies in PD models have revealed upregulation of NLRP3 expression within DANs and demonstrated that activation of NLRP3 inflammasome in neurons is sufficient to drive neuronal loss, whereas microglial activation occurs after neuronal death, and that inhibition of intraneuronal NLRP3 inflammasome prevents degeneration of DANs. In this review, we provide research evidence related to NLRP3 inflammasome in DANs in PD as well as focus on possible mechanisms of NLRP3 inflammasome activation in neurons, aiming to provide a new way of thinking about the pathogenesis and prevention of PD.

Liraglutide ameliorates delirium-like behaviors of aged mice undergoing cardiac surgery by mitigating microglia activation via promoting mitophagy

OBJECTIVE

Postoperative delirium (POD) is a prevalent complication in cardiac surgery patients, particularly the elderly, with neuroinflammation posited as a crucial contributing factor. We investigated the prophylactic effects of liraglutide, a GLP-1 analog, on delirium-like behaviors in aged mice undergoing cardiac surgery and explored the underlying mechanisms focusing on neuroinflammation, mitochondrial dysfunction, and synaptic plasticity.

METHODS

Using a cardiac ischemia-reperfusion animal model to mimic cardiac surgery, we assessed delirium-like behaviors, microglial activation, NLRP3 inflammasome activation, mitophagy, synaptic engulfment, and synaptic plasticity.

RESULTS

Cardiac surgery triggered delirium-like behaviors, concomitant with heightened microglial and NLRP3 inflammasome activation and impaired mitochondrial function and synaptic plasticity. Pretreatment with liraglutide ameliorated these adverse outcomes. Mechanistically, liraglutide enhanced mitophagy, thereby inhibiting NLRP3 inflammasome activation and subsequent microglial activation. Furthermore, liraglutide counteracted surgery-induced synaptic loss and impairment of synaptic plasticity.

CONCLUSION

Liraglutide exerts protective effects against delirium-like behaviors in aged mice post-cardiac surgery, potentially through bolstering microglia mitophagy, curtailing neuroinflammation, and preserving synaptic integrity. This highlights the potential of liraglutide as a promising perioperative strategy for delirium prevention in cardiac surgery patients.

Hypoxia inducible factor-1α regulates microglial innate immune memory and the pathology of Parkinson's disease

Neuroinflammation is one of the core pathological features of Parkinson's disease (PD). Innate immune cells play a crucial role in the progression of PD. Microglia, the major innate immune cells in the brain, exhibit innate immune memory effects and are recognized as key regulators of neuroinflammatory responses. Persistent modifications of microglia provoked by the first stimuli are pivotal for innate immune memory, resulting in an enhanced or suppressed immune response to second stimuli, which is known as innate immune training and innate immune tolerance, respectively. In this study, LPS was used to establish in vitro and in vivo models of innate immune memory. Microglia-specific Hif-1α knockout mice were further employed to elucidate the regulatory role of HIF-1α in innate immune memory and MPTP-induced PD pathology. Our results showed that different paradigms of LPS could induce innate immune training or tolerance in the nigrostriatal pathway of mice. We found that innate immune tolerance lasting for one month protected the dopaminergic system in PD mice, whereas the effect of innate immune training was limited. Deficiency of HIF-1α in microglia impeded the formation of innate immune memory and exerted protective effects in MPTP-intoxicated mice by suppressing neuroinflammation. Therefore, HIF-1α is essential for microglial innate immune memory and can promote neuroinflammation associated with PD.

Parthanatos: Mechanisms, modulation, and therapeutic prospects in neurodegenerative disease and stroke

Parthanatos is a cell death signaling pathway that has emerged as a compelling target for pharmaceutical intervention. It plays a pivotal role in the neuron loss and neuroinflammation that occurs in Parkinson's Disease (PD), Alzheimer's Disease (AD), Huntington's Disease (HD), Amyotrophic Lateral Sclerosis (ALS), and stroke. There are currently no treatments available to humans to prevent cell death in any of these diseases. This review provides an in-depth examination of the current understanding of the Parthanatos mechanism, with a particular focus on its implications in neuroinflammation and various diseases discussed herein. Furthermore, we thoroughly review potential intervention targets within the Parthanatos pathway. We dissect recent progress in inhibitory strategies, complimented by a detailed structural analysis of key Parthanatos executioners, PARP-1, AIF, and MIF, along with an assessment of their established inhibitors. We hope to introduce a new perspective on the feasibility of targeting components within the Parthanatos pathway, emphasizing its potential to bring about transformative outcomes in therapeutic interventions. By delineating therapeutic opportunities and known targets, we seek to emphasize the imperative of blocking Parthanatos as a precursor to developing disease-modifying treatments. This comprehensive exploration aims to catalyze a paradigm shift in our understanding of potential neurodegenerative disease therapeutics, advocating for the pursuit of effective interventions centered around Parthanatos inhibition.

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.

Disruption of the Na+/K+-ATPase-purinergic P2X7 receptor complex in microglia promotes stress-induced anxiety

Na+/K+-ATPase (NKA) plays an important role in the central nervous system. However, little is known about its function in the microglia. Here, we found that NKAα1 forms a complex with the purinergic P2X7 receptor (P2X7R), an adenosine 5'-triphosphate (ATP)-gated ion channel, under physiological conditions. Chronic stress or treatment with lipopolysaccharide plus ATP decreased the membrane expression of NKAα1 in microglia, facilitated P2X7R function, and promoted microglia inflammatory activation via activation of the NLRP3 inflammasome. Accordingly, global deletion or conditional deletion of NKAα1 in microglia under chronic stress-induced aggravated anxiety-like behavior and neuronal hyperexcitability. DR5-12D, a monoclonal antibody that stabilizes membrane NKAα1, improved stress-induced anxiety-like behavior and ameliorated neuronal hyperexcitability and neurogenesis deficits in the ventral hippocampus of mice. Our results reveal that NKAα1 limits microglia inflammation and may provide a target for the treatment of stress-related neuroinflammation and diseases.

TMT-based quantitative proteomics analysis of neuroprotective effects of Forsythoside A on the MPTP-induced Parkinson's disease mouse model

Parkinson's disease (PD) is a prevalent neurodegenerative disorder characteristized by the presence of dyskinesia and the progressive loss of dopaminergic neurons. Although certain drugs can mitigate the symptoms of PD, they are unable to delay the disease progression, and their prolonged use may result in complications. Therefore, there exists an urgent necessity to identify potential agents that can effectively delay PD progression with fewer side effects. Recent research has unveiled that several traditional Chinese medicines (TCM) exhibit neuroprotective properties in various models pertinent to PD. Forsythoside A (FSA), the primary bioactive compound derived from TCM Lianqiao, has undergone extensive research in animal models of Alzheimer's disease and cerebral ischemia. However, the investigation into the impact of FSA on PD is limited in existing research. In this study, we aimed to evaluate the neuroprotective effects of FSA on MPTP-induced PD mouse model. FSA demonstrated significant improvements in the behavioral and neuropathological changes triggered by MPTP in mice. Furthermore, it exerted a suppressive effect on the activations of astrocyte and microglia. Meanwhile, Tandem mass tag (TMT)-based quantitative proteomics of striatal tissue and bioinformatics analysis were performed to elucidate the underlying mechanisms of FSA on PD mouse model. Proteomics demonstrated a total of 68 differentially expressed proteins (DEPs) were identified between HFSA and MPTP groups including 26 upregulated and 42 downregulated. Systematic bioinformatics analysis of the 68 DEPs illustrated that they were predominantly related to estrogen signaling pathway and calcium signaling pathway. The related DEPs (PLCβ4, Grm2, HPAC and Cox4i1) expression levels were verified by Western blot. FSA effectively restored the altered expression of the four DEPs induced by MPTP. Summarily, FSA exerted remarkable neuroprotective effects in MPTP-induced mice. Further, our research may provide proteomics insights that contribute to the further exploration of FSA as a potential treatment for PD.

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.

Calcitriol attenuates lipopolysaccharide-induced neuroinflammation and depressive-like behaviors by suppressing the P2X7R/NLRP3/caspase-1 pathway

RATIONALE

Microglia-mediated neuroinflammation is a vital hallmark in progression of depression, while calcitriol exerts anti-inflammatory effects in the brain. The activation of the P2X7 receptor has an important link to neuroinflammation. However, it is unclear whether calcitriol treatment exerts anti-inflammatory effects in association with P2X7R activation.

OBJECTIVE

In this study, we assessed the antidepressive and neuroprotective effects of calcitriol on lipopolysaccharide (LPS)-mediated depressive-like behavior, neuroinflammation, and neuronal damage.

METHODS

In in vitro experiments, the BV2 cells were exposed to LPS, and the protective effects of calcitriol were assessed. For in vivo experiment, thirty-two male C57BL/6 mice were divided into four groups of control, calcitriol, LPS and LPS + calcitriol. Calcitriol was administered at 1 µg/kg for 14 days and LPS at 1 mg/kg once every other day for 14 days. The control group mice were given equal volumes of vehicles. All treatments were delivered intraperitoneally.

RESULTS

The in vitro experiments showed calcitriol inhibited the release of inflammatory mediators induced by LPS in BV2 cells. The in vivo experiments revealed that calcitriol alleviated LPS-induced behavioral abnormalities and spatial learning impairments. Moreover, calcitriol treatment reduced the mRNA levels of pro-inflammatory cytokines, while increasing anti-inflammatory cytokine levels in the hippocampus. Our results further revealed that calcitriol administration attenuated LPS-induced microglia activation by suppressing P2X7R/NLRP3/caspase-1 signaling. Moreover, calcitriol inhibited apoptosis of neurons in the hippocampus as evidenced by expression of apoptosis-related proteins and TUNEL assay.

CONCLUSIONS

Collectively, our findings demonstrated that calcitriol exerts antidepressive and neuroprotective effects through the suppression of the P2X7R/NLRP3/caspase-1 pathway both in LPS-induced inflammation models in vitro and in vivo.

Minocycline alleviates LPS-induced cognitive dysfunction in mice by inhibiting the NLRP3/caspase-1 pathway

BACKGROUND

Growing experimental evidence indicates that cognitive impairment is linked to neuroinflammation. Minocycline (MINO), an antibiotic known for its anti-inflammatory, has shown promise in alleviating cognitive impairment. Nonetheless, the exact mechanism through which MINO improves cognitive impairment is not yet understood.

METHODS

A neuroinflammatory model was establish by utilizing lipopolysaccharide. The assessment of mice's cognitive and learning abilities was conducted through the MWM and Y-maze tests. The evaluation of hippocampal neuronal injury and microglial activation were achieved by performing HE staining and IHC, respectively. To evaluate BV2 cell viability and apoptosis, the CCK-8 and Hoechst 33342/PI staining assays were employed. In order to assess the protein and RNA expression levels of NLRP3, caspase-1, IL-1β, IL-18, Iba-1, and Bcl2/Bax, WB and RT-qPCR were utilized. Additionally, the inhibitory effect of MINO on apoptosis by targeting the NLRP3/caspase-1 pathway was investigated using Nigericin.

RESULTS

MINO was effective in reducing the time it took for mice to escape from the test, increasing the number of platforms they crossed, and mitigating damage to the hippocampus while also suppressing microglial activation and the expression of Iba-1 in a neuroinflammatory model caused by LPS. Furthermore, MINO improved the viability of BV2 cell and reduced apoptosis. It also had the effect of reducing the expression levels of NLRP3/Caspase-1, IL-1β, IL-18, and BAX, while upregulating the expression of Bcl2. Additionally, MINO was found to downregulate the NLRP3 expression, which is specifically activated by nigericin.

CONCLUSION

The protective effect of MINO relies on the crucial involvement of the NLRP3/caspase-1 pathway.

Neuroprotective potentials of Lead phytochemicals against Alzheimer's disease with focus on oxidative stress-mediated signaling pathways: Pharmacokinetic challenges, target specificity, clinical trials and future perspectives

BACKGROUND

Alzheimer's diseases (AD) and dementia are among the highly prevalent neurological disorders characterized by deposition of beta amyloid (Aβ) plaques, dense deposits of highly phosphorylated tau proteins, insufficiency of acetylcholine (ACh) and imbalance in glutamatergic system. Patients typically experience cognitive, behavioral alterations and are unable to perform their routine activities. Evidence also suggests that inflammatory processes including excessive microglia activation, high expression of inflammatory cytokines and release of free radicals. Thus, targeting inflammatory pathways beside other targets might be the key factors to control- disease symptoms and progression.

PURPOSE

This review is aimed to highlight the mechanisms and pathways involved in the neuroprotective potentials of lead phytochemicals. Further to provide updates regarding challenges associated with their use and their progress into clinical trials as potential lead compounds.

METHODS

Most recent scientific literature on pre-clinical and clinical data published in quality journals especially on the lead phytochemicals including curcumin, catechins, quercetin, resveratrol, genistein and apigenin was collected using SciFinder, PubMed, Google Scholar, Web of Science, JSTOR, EBSCO, Scopus and other related web sources.

RESULTS

Literature review indicated that the drug discovery against AD is insufficient and only few drugs are clinically approved which have limited efficacy. Among the therapeutic options, natural products have got tremendous attraction owing to their molecular diversity, their safety and efficacy. Research suggest that natural products can delay the disease onset, reduce its progression and regenerate the damage via their anti-amyloid, anti-inflammatory and antioxidant potentials. These agents regulate the pathways involved in the release of neurotrophins which are implicated in neuronal survival and function. Highly potential lead phytochemicals including curcumin, catechins, quercetin, resveratrol, genistein and apigenin regulate neuroprotective signaling pathways implicated in neurotrophins-mediated activation of tropomyosin receptor kinase (Trk) and p75 neurotrophins receptor (p75NTR) family receptors.

CONCLUSIONS

Phytochemicals especially phenolic compounds were identified as highly potential molecules which ameliorate oxidative stress induced neurodegeneration, reduce Aβ load and inhibit vital enzymes. Yet their clinical efficacy and bioavailability are the major challenges which need further interventions for more effective therapeutic outcomes.

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.

Management of the Brain: Essential Oils as Promising Neuroinflammation Modulator in Neurodegenerative Diseases

Neuroinflammation, a pivotal factor in the pathogenesis of various brain disorders, including neurodegenerative diseases, has become a focal point for therapeutic exploration. This review highlights neuroinflammatory mechanisms that hallmark neurodegenerative diseases and the potential benefits of essential oils in counteracting neuroinflammation and oxidative stress, thereby offering a novel strategy for managing and mitigating the impact of various brain disorders. Essential oils, derived from aromatic plants, have emerged as versatile compounds with a myriad of health benefits. Essential oils exhibit robust antioxidant activity, serving as scavengers of free radicals and contributing to cellular defense against oxidative stress. Furthermore, essential oils showcase anti-inflammatory properties, modulating immune responses and mitigating inflammatory processes implicated in various chronic diseases. The intricate mechanisms by which essential oils and phytomolecules exert their anti-inflammatory and antioxidant effects were explored, shedding light on their multifaceted properties. Notably, we discussed their ability to modulate diverse pathways crucial in maintaining oxidative homeostasis and suppressing inflammatory responses, and their capacity to rescue cognitive deficits observed in preclinical models of neurotoxicity and neurodegenerative diseases.

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.

Total Glucosides of White Paeony Capsule ameliorates Parkinson's disease-like behavior in MPTP-induced mice model by regulating LRRK2/alpha-synuclein signaling

ETHNOPHARMACOLOGICAL RELEVANCE

The Total Glucosides of White Paeony Capsule (TGPC), one of the traditional Chinese patent medicines, has been used for the treatment of autoimmune diseases such as rheumatoid arthritis (RA) in clinical practice. Besides, the components of TGPC are extracted from Radix Paeoniae Alba (RPA) and have displayed neuroprotective properties.

AIM OF THE STUDY

The present study was designed to evaluate the anti-PD-like effects of TGPC on a 1-methyl-4-phenyl-1, 2, 3, 6-tetrahydropyridine (MPTP)-induced mice model and explore its potential molecular mechanisms.

MATERIALS AND METHODS

Behavioral tests, hematoxylin and eosin (HE) staining, Nissl staining, immunohistochemistry (IHC), western blotting (WB) and Enzyme-Linked Immunosorbent Assay (ELISA) were performed in this study.

RESULTS

It was observed that TGPC treatment (150, 300 mg/kg) significantly reversed MPTPinduced PD-like behaviors, such as reduced locomotive activity in the open field test, prolonged time to turn downward on the ball (T-turn) and to climb down the whole pole (T-descend) in the pole test, decreased movement scores in the traction test and extended the latency to fall in the hanging wire test. In addition, TGPC improved neurodegeneration, inhibited the excessive activation of microglia and suppressed the overproduction of proinflammatory cytokines induced by MPTP, partially by restoring leucine-rich repeat kinase 2 (LRRK2) activity and inhibiting alpha-synuclein (α-syn) mediated neuroinflammation signaling.

CONCLUSION

Taken together, TGPC exhibited neuroprotective effects on MPTP-induced mice model of PD, which was associated with the prevention of neuroinflammation and neurodegeneration modulated by LRRK2/α-syn pathway.

The involvement of α-synucleinopathy in the disruption of microglial homeostasis contributes to the pathogenesis of Parkinson's disease

The intracellular deposition and intercellular transmission of α-synuclein (α-syn) are shared pathological characteristics among neurodegenerative disorders collectively known as α-synucleinopathies, including Parkinson's disease (PD). Although the precise triggers of α-synucleinopathies remain unclear, recent findings indicate that disruption of microglial homeostasis contributes to the pathogenesis of PD. Microglia play a crucial role in maintaining optimal neuronal function by ensuring a homeostatic environment, but this function is disrupted during the progression of α-syn pathology. The involvement of microglia in the accumulation, uptake, and clearance of aggregated proteins is critical for managing disease spread and progression caused by α-syn pathology. This review summarizes current knowledge on the interrelationships between microglia and α-synucleinopathies, focusing on the remarkable ability of microglia to recognize and internalize extracellular α-syn through diverse pathways. Microglia process α-syn intracellularly and intercellularly to facilitate the α-syn neuronal aggregation and cell-to-cell propagation. The conformational state of α-synuclein distinctly influences microglial inflammation, which can affect peripheral immune cells such as macrophages and lymphocytes and may regulate the pathogenesis of α-synucleinopathies. We also discuss ongoing research efforts to identify potential therapeutic approaches targeting both α-syn accumulation and inflammation in PD. Video Abstract.

Inflammation in Metal-Induced Neurological Disorders and Neurodegenerative Diseases

Essential metals play critical roles in maintaining human health as they participate in various physiological activities. Nonetheless, both excessive accumulation and deficiency of these metals may result in neurotoxicity secondary to neuroinflammation and the activation of microglia and astrocytes. Activation of these cells can promote the release of pro-inflammatory cytokines. It is well known that neuroinflammation plays a critical role in metal-induced neurotoxicity as well as the development of neurological disorders, such as Alzheimer's disease (AD), Parkinson's disease (PD), and multiple sclerosis (MS). Initially seen as a defense mechanism, persistent inflammatory responses are now considered harmful. Astrocytes and microglia are key regulators of neuroinflammation in the central nervous system, and their excessive activation may induce sustained neuroinflammation. Therefore, in this review, we aim to emphasize the important role and molecular mechanisms underlying metal-induced neurotoxicity. Our objective is to raise the awareness on metal-induced neuroinflammation in neurological disorders. However, it is not only just neuroinflammation that different metals could induce; they can also cause harm to the nervous system through oxidative stress, apoptosis, and autophagy, to name a few. The primary pathophysiological mechanism by which these metals induce neurological disorders remains to be determined. In addition, given the various pathways through which individuals are exposed to metals, it is necessary to also consider the effects of co-exposure to multiple metals on neurological disorders.

Immunological dimensions of neuroinflammation and microglial activation: exploring innovative immunomodulatory approaches to mitigate neuroinflammatory progression

The increasing life expectancy has led to a higher incidence of age-related neurodegenerative conditions. Within this framework, neuroinflammation emerges as a significant contributing factor. It involves the activation of microglia and astrocytes, leading to the release of pro-inflammatory cytokines and chemokines and the infiltration of peripheral leukocytes into the central nervous system (CNS). These instances result in neuronal damage and neurodegeneration through activated nucleotide-binding domain and leucine-rich repeat containing (NLR) family pyrin domain containing protein 3 (NLRP3) and nuclear factor kappa B (NF-kB) pathways and decreased nuclear factor erythroid 2-related factor 2 (Nrf2) activity. Due to limited effectiveness regarding the inhibition of neuroinflammatory targets using conventional drugs, there is challenging growth in the search for innovative therapies for alleviating neuroinflammation in CNS diseases or even before their onset. Our results indicate that interventions focusing on Interleukin-Driven Immunomodulation, Chemokine (CXC) Receptor Signaling and Expression, Cold Exposure, and Fibrin-Targeted strategies significantly promise to mitigate neuroinflammatory processes. These approaches demonstrate potential anti-neuroinflammatory effects, addressing conditions such as Multiple Sclerosis, Experimental autoimmune encephalomyelitis, Parkinson's Disease, and Alzheimer's Disease. While the findings are promising, immunomodulatory therapies often face limitations due to Immune-Related Adverse Events. Therefore, the conduction of randomized clinical trials in this matter is mandatory, and will pave the way for a promising future in the development of new medicines with specific therapeutic targets.

The role of inflammasomes in human diseases and their potential as therapeutic targets

Inflammasomes are large protein complexes that play a major role in sensing inflammatory signals and triggering the innate immune response. Each inflammasome complex has three major components: an upstream sensor molecule that is connected to a downstream effector protein such as caspase-1 through the adapter protein ASC. Inflammasome formation typically occurs in response to infectious agents or cellular damage. The active inflammasome then triggers caspase-1 activation, followed by the secretion of pro-inflammatory cytokines and pyroptotic cell death. Aberrant inflammasome activation and activity contribute to the development of diabetes, cancer, and several cardiovascular and neurodegenerative disorders. As a result, recent research has increasingly focused on investigating the mechanisms that regulate inflammasome assembly and activation, as well as the potential of targeting inflammasomes to treat various diseases. Multiple clinical trials are currently underway to evaluate the therapeutic potential of several distinct inflammasome-targeting therapies. Therefore, understanding how different inflammasomes contribute to disease pathology may have significant implications for developing novel therapeutic strategies. In this article, we provide a summary of the biological and pathological roles of inflammasomes in health and disease. We also highlight key evidence that suggests targeting inflammasomes could be a novel strategy for developing new disease-modifying therapies that may be effective in several conditions.

Baicalin exerts neuroprotective actions by regulating the Nrf2-NLRP3 axis in toxin-induced models of Parkinson's disease

Baicalin, a potent anti-oxidative and anti-inflammatory flavonoid compound derived from Scutellaria baicalensis, has emerged as a neuroprotective agent. However, the mechanisms by which baicalin is neuroprotective in Parkinson's disease (PD) remain unclear. In this research, α-syn/MPP+ and MPTP were used to establish PD models in BV2 cells and C57BL/6 mice, respectively. The effect and mechanism of action of baicalin in PD were investigated by Western blotting, RT-qPCR, ELISA, Immunohistochemistry (IHC) staining, Immunofluorescence (IF) staining, HPLC and methods. Results demonstrate that baicalin mitigates oxidative stress, microglia activation and inflammatory response caused by α-syn/MPP+ and MPTP. It protects against dopaminergic neuron loss and relieves motor deficits. Meanwhile, baicalin not only significantly up-regulates the expression of Nrf2 and its downstream antioxidant enzyme, but also suppresses the activation of NLRP3 inflammasome simultaneously. Notably, the beneficial effects of baicalin in PD treatment are blocked by Nrf2 knockdown. This research reveals that baicalin may exert neuroprotective effects in PD treatment by suppressing the activation of NLRP3 inflammasome and it is dependent on the Nrf2-mediated antioxidative response.

Drugging the NLRP3 inflammasome: from signalling mechanisms to therapeutic targets

Diseases associated with chronic inflammation constitute a major health burden across the world. As central instigators of the inflammatory response to infection and tissue damage, inflammasomes - and the NACHT, LRR and PYD domain-containing protein 3 (NLRP3) inflammasome in particular - have emerged as key regulators in diverse rheumatic, metabolic and neurodegenerative diseases. Similarly to other inflammasome sensors, NLRP3 assembles a cytosolic innate immune complex that activates the cysteine protease caspase-1, which in turn cleaves gasdermin D (GSDMD) to induce pyroptosis, a regulated mode of lytic cell death. Pyroptosis is highly inflammatory, partly because of the concomitant extracellular release of the inflammasome-dependent cytokines IL-1β and IL-18 along with a myriad of additional danger signals and intracellular antigens. Here, we discuss how NLRP3 and downstream inflammasome effectors such as GSDMD, apoptosis-associated speck-like protein containing a CARD (ASC) and nerve injury-induced protein 1 (NINJ1) have gained significant traction as therapeutic targets. We highlight the recent progress in developing small-molecule and biologic inhibitors that are advancing into the clinic and serving to harness the broad therapeutic potential of modulating the NLRP3 inflammasome.

Echinacoside exerts neuroprotection via suppressing microglial α-synuclein/TLR2/NF-κB/NLRP3 axis in parkinsonian models

BACKGROUND

Echinacoside (ECH), a natural active compound, was found to exert neuroprotection in Parkinson's disease (PD). However, the underlying molecular mechanisms remain controversial.

PURPOSE

This study aimed to explore the roles of ECH in PD and its engaged mechanisms.

CONCLUSION

In vivo, MPTP was adapted to construct subacute PD mouse model to explore the regulation of ECH on NLRP3 inflammasome. In vitro, α-synuclein (α-syn)/MPP+ was used to mediate the activation of NLRP3 inflammasome in BV2 cells, and the mechanism of ECH regulation of it was explored with molecular docking, immunofluorescence, Western blotting, and small molecule inhibitors.

CONCLUSION

The activation of microglial NLRP3 inflammasome could be evoked by MPTP in vitro, but its toxic metabolite MPP+ alone cannot trigger the activation of NLRP3 inflammasome in vitro, which requires α-synuclein (α-syn) priming. Exogenous α-syn could evoke microglial TLR2/NF-κB/NLRP3 axis, playing the priming role in MPP+ -mediated NLRP3 inflammasome activation. ECH can suppress the upregulation of α-syn in MPTP-treated mice and BV2 microglia. It can also suppress the activation of the TLR2/NF-κB/NLRP3 axis induced by α-syn.

CONCLUSION

ECH exerts neuroprotective effects by downregulating the TLR2/NF-κB/NLRP3 axis via reducing the expression of α-syn in the PD models.

Gut microbiota-associated taurine metabolism dysregulation in a mouse model of Parkinson's disease

IMPORTANCE

PD is recognized as a multisystem disease concerning GI dysfunction and microbiota dysbiosis but still lacks ideal therapies. Recently, aberrant microbiota-derived metabolites are emerging as important participants in PD etiology. However, the alterations of gut microbiota community and serum untargeted metabolite profile have not been fully investigated in a PD mice model. Here, we discover sharply reduced levels of Lactobacillus and taurine in MPTP-treated mice. Moreover, Lactobacillus, Adlercreutzia, and taurine-related metabolites showed the most significant correlation with pathological and GI performance of PD mice. The abundances of microbial transporter and enzymes participating in the degeneration of taurine were disturbed in PD mice. Most importantly, taurine supplement ameliorates MPTP-induced motor deficits, DA neuron loss, and microglial activation. Our data highlight the impaired taurine-based microbiome-metabolism axis during the progression of PD and reveal a novel and previously unrecognized role of genera in modulating taurine metabolism.

MLKL deficiency alleviates neuroinflammation and motor deficits in the α-synuclein transgenic mouse model of Parkinson's disease

Parkinson's disease (PD), one of the most devastating neurodegenerative brain disorders, is characterized by the progressive loss of dopaminergic neurons in the substantia nigra (SN) and deposits of α-synuclein aggregates. Currently, pharmacological interventions for PD remain inadequate. The cell necroptosis executor protein MLKL (Mixed-lineage kinase domain-like) is involved in various diseases, including inflammatory bowel disease and neurodegenerative diseases; however, its precise role in PD remains unclear. Here, we investigated the neuroprotective role of MLKL inhibition or ablation against primary neuronal cells and human iPSC-derived midbrain organoids induced by toxic α-Synuclein preformed fibrils (PFFs). Using a mouse model (Tg-Mlkl-/-) generated by crossbreeding the SNCA A53T synuclein transgenic mice with MLKL knockout (KO)mice, we assessed the impact of MLKL deficiency on the progression of Parkinsonian traits. Our findings demonstrate that Tg-Mlkl-/- mice exhibited a significant improvement in motor symptoms and reduced phosphorylated α-synuclein expression compared to the classic A53T transgenic mice. Furthermore, MLKL deficiency alleviated tyrosine hydroxylase (TH)-positive neuron loss and attenuated neuroinflammation by inhibiting the activation of microglia and astrocytes. Single-cell RNA-seq (scRNA-seq) analysis of the SN of Tg-Mlkl-/- mice revealed a unique cell type-specific transcriptome profile, including downregulated prostaglandin D synthase (PTGDS) expression, indicating reduced microglial cells and dampened neuron death. Thus, MLKL represents a critical therapeutic target for reducing neuroinflammation and preventing motor deficits in PD.

Bridging the Gap: Investigating the Link between Inflammasomes and Postoperative Cognitive Dysfunction

Postoperative cognitive dysfunction (POCD) is a cluster of cognitive problems that may arise after surgery. POCD symptoms include memory loss, focus inattention, and communication difficulties. Inflammasomes, intracellular multiprotein complexes that control inflammation, may have a significant role in the development of POCD. It has been postulated that the NLRP3 inflammasome promotes cognitive impairment by triggering the inflammatory response in the brain. Nevertheless, there are many gaps in the current literature to understand the underlying pathophysiological mechanisms and develop future therapy. This review article underlines the limits of our current knowledge about the NLRP3 (NOD-, LRR- and pyrin domain-containing protein 3) inflammasome and POCD. We first discuss inflammasomes and their types, structures, and functions, then summarize recent evidence of the NLRP3 inflammasome's involvement in POCD. Next, we propose a hypothesis that suggests the involvement of inflammasomes in multiple organs, including local surgical sites, blood circulation, and other peripheral organs, leading to systemic inflammation and subsequent neuronal dysfunction in the brain, resulting in POCD. Research directions are then discussed, including analyses of inflammasomes in more clinical POCD animal models and clinical trials, studies of inflammasome types that are involved in POCD, and investigations into whether inflammasomes occur at the surgical site, in circulating blood, and in peripheral organs. Finally, we discuss the potential benefits of using new technologies and approaches to study inflammasomes in POCD. A thorough investigation of inflammasomes in POCD might substantially affect clinical practice.

β-Caryophyllene decreases neuroinflammation and exerts neuroprotection of dopaminergic neurons in a model of hemiparkinsonism through inhibition of the NLRP3 inflammasome

INTRODUCTION

Parkinson's disease represents a neurodegenerative condition characterized by the progressive loss of dopaminergic neurons within the Substantia Nigra pars compacta (SNpc), resulting in diminished dopamine levels in the striatum (STR) and chronic neuroinflammation. Recent investigations have proposed the neuroprotective potential of the endocannabinoid system in neurodegenerative disorders. β-caryophyllene (BCP) is recognized for its antioxidant and anti-inflammatory properties, attributed to its activation of the type 2 cannabinoid receptor. This study aimed to assess the neuroprotective impact of BCP on dopaminergic neurons, with a particular focus on inhibiting the NLRP3 inflammasome.

METHODS

A model of hemiparkinsonism, induced by 6-hydroxydopamine (6-OHDA), served as the experimental framework. Motor function was evaluated using the cylinder test, and inflammasome inhibition was determined by assessing the expression of NLRP3, caspase-1, and the pro-inflammatory cytokine IL-1β in both the SNpc and STR through ELISA analysis. Furthermore, the evaluation of oxidative stress was facilitated by quantifying malondialdehyde (MDA) levels in the same regions.

RESULTS

BCP treatment demonstrated significant improvements in motor dysfunction, as assessed by the cylinder test (p=0.0011) and exhibited a neuroprotective effect on dopaminergic neurons within the SNpc (p=0.0017), as well as nerve fibers in the STR (p=0.0399). In terms of its ability to inhibit the inflammasome, BCP led to decreased expression levels of NLRP3 (p=0.0401 in STR and p = 0.0139 in SNpc), caspase-1 (p=0.0004 in STR), and MDA (p=0.0085 in STR and p=0.0414 in SNpc).

CONCLUSION

These results point to BCP's potential in mitigating the motor deficit, inhibiting NLRP3 inflammasome activation, and attenuating lipid peroxidation induced by 6-OHDA.

The interplay between α-Synuclein and NLRP3 inflammasome in Parkinson's disease

α-Synuclein is a member of a protein of synucleins, which is a presynaptic neuron protein. It is usually highly expressed in the brain and participates in the formation and transmission of nerve synapses. It has been reported that abnormal aggregation of α-Syn can induce the activation of NLRP3 inflammasome in microglia, increase the production of IL-1β, and aggravate neuroinflammation. Therefore, it is recognized as one of the important factors leading to neuroinflammation in Parkinson's disease. In this paper, we aimed to explore the influence of post-translational modification of α-Syn on its pathological aggregation and summarize various pathways that activate NLRP3 triggered by α-Syn and targeted therapeutic strategies, which provided new insights for further exploring the origin and targeted therapy of Parkinson's disease.

To re-examine the intersection of microglial activation and neuroinflammation in neurodegenerative diseases from the perspective of pyroptosis

Neurodegenerative diseases (NDs), such as Alzheimer's disease, Parkinson's disease, Huntington's disease, and motor neuron disease, are diseases characterized by neuronal damage and dysfunction. NDs are considered to be a multifactorial disease with diverse etiologies (immune, inflammatory, aging, genetic, etc.) and complex pathophysiological processes. Previous studies have found that neuroinflammation and typical microglial activation are important mechanisms of NDs, leading to neurological dysfunction and disease progression. Pyroptosis is a new mode involved in this process. As a form of programmed cell death, pyroptosis is characterized by the expansion of cells until the cell membrane bursts, resulting in the release of cell contents that activates a strong inflammatory response that promotes NDs by accelerating neuronal dysfunction and abnormal microglial activation. In this case, abnormally activated microglia release various pro-inflammatory factors, leading to the occurrence of neuroinflammation and exacerbating both microglial and neuronal pyroptosis, thus forming a vicious cycle. The recognition of the association between pyroptosis and microglia activation, as well as neuroinflammation, is of significant importance in understanding the pathogenesis of NDs and providing new targets and strategies for their prevention and treatment.

Targeting NLRP3 inflammasome for neurodegenerative disorders

Neuroinflammation is a key pathological feature in neurological diseases, including Alzheimer's disease (AD). The nucleotide-binding domain leucine-rich repeat-containing proteins (NLRs) belong to the pattern recognition receptors (PRRs) family that sense stress signals, which play an important role in inflammation. As a member of NLRs, the NACHT, LRR and PYD domains-containing protein 3 (NLRP3) is predominantly expressed in microglia, the principal innate immune cells in the central nervous system (CNS). Microglia release proinflammatory cytokines to cause pyroptosis through activating NLRP3 inflammasome. The active NLRP3 inflammasome is involved in a variety of neurodegenerative diseases (NDs). Recent studies also indicate the key role of neuronal NLRP3 in the pathogenesis of neurological disorders. In this article, we reviewed the mechanisms of NLRP3 expression and activation and discussed the role of active NLRP3 inflammasome in the pathogenesis of NDs, particularly focusing on AD. The studies suggest that targeting NLRP3 inflammasome could be a novel approach for the disease modification.

The STING inhibitor C-176 attenuates MPTP-induced neuroinflammation and neurodegeneration in mouse parkinsonian models

Recent emerging evidence reveals that cGAS-STING-mediated Type I interferon (IFN) signaling axis takes part in the microglial-associated neuroinflammation. However, the potential role of pharmacological inhibition of STING on neuroinflammation and dopaminergic neurodegeneration remains unknown. In the present study, we investigated whether pharmacological inhibition of STING attenuates neuroinflammation and neurodegeneration in experimental models of Parkinson's disease. We report that therapeutic inhibition of STING with C-176 significantly inhibited the activation of downstream signaling pathway, suppressed neuroinflammation, and ameliorated MPTP-induced dopaminergic neurotoxicity and motor deficit. Furthermore, pharmacological inhibition of STING with C-176 attenuated proinflammatory response in BV2 microglial cells exposed to LPS/MPP+. More importantly, C-176 also reduced NLRP3 inflammasome activation both in vitro and in vivo. The results of our study suggest that pharmacologic inhibition of STING protects against dopaminergic neurodegeneration and neuroinflammation that may act at least in part through suppressing NLRP3 inflammasome activation. STING signaling may hold great promise for the development of new treatment strategy for PD.

A review of studies on the implication of NLRP3 inflammasome for Parkinson's disease and related candidate treatment targets

Parkinson's disease (PD) is a neurodegenerative disease for which the prevalence is second only to Alzheimer's disease (AD). This disease primarily affects people of middle and old age, significantly impacting their health and quality of life. The main pathological features include the degenerative nigrostriatal dopaminergic (DA) neuron loss and Lewy body (LB) formation. Currently, available PD medications primarily aim to alleviate clinical symptoms, however, there is no universally recognized therapy worldwide that effectively prevents, clinically treats, stops, or reverses the disease. Consequently, the evaluation and exploration of potential therapeutic targets for PD are of utmost importance. Nevertheless, the pathophysiology of PD remains unknown, and neuroinflammation mediated by inflammatory cytokines that prompts neuron death is fundamental for the progression of PD. The nucleotide-binding oligomerization domain-like receptor pyrin domain-containing 3 (NLRP3) inflammasome is a key complex of proteins linking the neuroinflammatory cascade in PD. Moreover, mounting evidence suggests that traditional Chinese medicine (TCM) alleviates PD by suppressing the NLRP3 inflammasome. This article aims to comprehensively review the available studies on the composition and activating mechanism of the NLRP3 inflammasome, along with its significance in PD pathogenesis and potential treatment targets. We also review natural products or synthetic compounds which reduce neuroinflammation via modulating NLRP3 inflammasome activity, aiming to identify new targets for future PD diagnosis and treatment through the exploration of NLRP3 inhibitors. Additionally, this review offers valuable references for developing new PD treatment methods.

Complement C1q-dependent engulfment of alpha-synuclein induces ENS-resident macrophage exhaustion and accelerates Parkinson's-like gut pathology

Deposition of misfolded α-synuclein (αsyn) in the enteric nervous system (ENS) is found in multiple neurodegenerative diseases. It is hypothesized that ENS synucleinopathy contributes to both the pathogenesis and non-motor morbidity in Parkinson's Disease (PD), but the cellular and molecular mechanisms that shape enteric histopathology and dysfunction are poorly understood. Here, we demonstrate that ENS-resident macrophages, which play a critical role in maintaining ENS homeostasis, initially respond to enteric neuronal αsyn pathology by upregulating machinery for complement-mediated engulfment. Pharmacologic depletion of ENS-macrophages or genetic deletion of C1q enhanced enteric neuropathology. Conversely, C1q deletion ameliorated gut dysfunction, indicating that complement partially mediates αsyn-induced gut dysfunction. Internalization of αsyn led to increased endo-lysosomal stress that resulted in macrophage exhaustion and temporally correlated with the progression of ENS pathology. These novel findings highlight the importance of enteric neuron-macrophage interactions in removing toxic protein aggregates that putatively shape the earliest stages of PD in the periphery.

Association between the risk and severity of Parkinson's disease and plasma homocysteine, vitamin B12 and folate levels: a systematic review and meta-analysis

Background

Parkinson's disease (PD) is recognized as the second most prevalent progressive neurodegenerative disease among the elderly. However, the relationship between PD and plasma homocysteine (Hcy), vitamin B12, and folate has yielded inconsistent results in previous studies. Hence, in order to address this ambiguity, we conducted a meta-analysis to summarize the existing evidence.

Methods

Suitable studies published prior to May 2023 were identified by searching PubMed, EMBASE, Medline, Ovid, and Web of Science. The methodological quality of eligible studies was assessed using the Newcastle-Ottawa Quality Assessment Scale (NOS). Meta-analysis and publication bias were then performed using R version 4.3.1.

Results

The results of our meta-analysis, consisting of case-control and cross-sectional studies, showed that PD patients had lower folate and vitamin B12 levels (SMD [95%CI]: -0.30[-0.39, -0.22], p < 0.001 for Vitamin B12; SMD [95%CI]: -0.20 [-0.28, -0.13], p < 0.001 for folate), but a significant higher Hcy level (SMD [95%CI]: 0.86 [0.59, 1.14], p < 0.001) than healthy people. Meanwhile, PD was significantly related to hyperhomocysteinemia (SMD [95%]: 2.02 [1.26, 2.78], p < 0.001) rather than plasma Hcy below 15 μmol/L (SMD [95%]: -0.31 [-0.62, 0.00], p = 0.05). Subgroup analysis revealed associations between the Hcy level of PD patients and region (p = 0.03), age (p = 0.03), levodopa therapy (p = 0.03), Hoehn and Yahr stage (p < 0.001), and cognitive impairment (p < 0.001). However, gender (p = 0.38) and sample size (p = 0.49) were not associated.

Conclusion

Hcy, vitamin B12, and folic acid potentially predict the onset and development of PD. Additionally, multiple factors were linked to Hcy levels in PD patients. Further studies are needed to comprehend their roles in PD.

Role of Nanoparticle-Conjugates and Nanotheranostics in Abrogating Oxidative Stress and Ameliorating Neuroinflammation

Oxidative stress is a deteriorating condition that arises due to an imbalance between the reactive oxygen species and the antioxidant system or defense of the body. The key reasons for the development of such conditions are malfunctioning of various cell organelles, such as mitochondria, endoplasmic reticulum, and Golgi complex, as well as physical and mental disturbances. The nervous system has a relatively high utilization of oxygen, thus making it particularly vulnerable to oxidative stress, which eventually leads to neuronal atrophy and death. This advances the development of neuroinflammation and neurodegeneration-associated disorders such as Alzheimer's disease, Parkinson's disease, epilepsy, dementia, and other memory disorders. It is imperative to treat such conditions as early as possible before they worsen and progress to irreversible damage. Oxidative damage can be negated by two mechanisms: improving the cellular defense system or providing exogenous antioxidants. Natural antioxidants can normally handle such oxidative stress, but they have limited efficacy. The valuable features of nanoparticles and/or nanomaterials, in combination with antioxidant features, offer innovative nanotheranostic tools as potential therapeutic modalities. Hence, this review aims to represent novel therapeutic approaches like utilizing nanoparticles with antioxidant properties and nanotheranostics as delivery systems for potential therapeutic applications in various neuroinflammation- and neurodegeneration-associated disease conditions.

Pharmacological intervention of curcumin via the NLRP3 inflammasome in ischemic stroke

Ischemic-induced neuronal injury arises due to low oxygen/nutrient levels and an inflammatory response that exacerbates neuronal loss. NOD-like receptor family pyrin domain-containing 3 (NLRP3) is an important regulator of inflammation after ischemic stroke, with its inhibition being involved in nerve regeneration. Curcumin, a main active ingredient in Chinese herbs, plays a positive role in neuronal repair and neuroprotection by regulating the NLRP3 signaling pathway. Nevertheless, the signaling mechanisms relating to how curcumin regulates NLRP3 inflammasome in inflammation and neural restoration following ischemic stroke are unknown. In this report, we summarize the main biological functions of the NLRP3 inflammasome along with the neuroprotective effects and underlying mechanisms of curcumin via impairment of the NLRP3 pathway in ischemic brain injury. We also discuss the role of medicinal interventions that target the NLRP3 and potential pathways, as well as possible directions for curcumin therapy to penetrate the blood-brain barrier (BBB) and hinder inflammation in ischemic stroke. This report conclusively demonstrates that curcumin has neuroprotective properties that inhibit inflammation and prevent nerve cell loss, thereby delaying the progression of ischemic brain damage.

Mefloquine targets NLRP3 to reduce lipopolysaccharide-induced systemic inflammation and neural injury

The NLR family pyrin domain containing 3 (NLRP3) inflammasome plays an important role in the pathogenesis of a wide variety of human diseases. So far, drugs directly and specifically targeting the NLRP3 inflammasome are not available for clinical use since the safety and efficacy of new compounds are often unclear. A promising approach is thus to identify NLRP3 inhibitors from existing drugs that are already in clinical use. Here, we show that mefloquine, a well-known antimalarial drug, is a highly selective and potent NLRP3 inhibitor by screening a FDA-approved drug library. Mechanistically, mefloquine directly binds to the NLRP3 NACHT and LRR domains to prevent NLRP3 inflammasome activation. More importantly, mefloquine treatment attenuates the symptoms of lipopolysaccharide-induced systemic inflammation and Parkinson's disease-like neural damage in mice. Our findings identify mefloquine as a potential therapeutic agent for NLRP3-driven diseases and migth expand its clinical use considerably.

Cystathionine β-Synthase Suppresses NLRP3 Inflammasome Activation via Redox Regulation in Microglia

Aims: Cystathionine β-synthase (CBS) is essential for homocysteine (Hcy) transsulfuration, yielding cysteine as a common precursor of hydrogen sulfide (H2S), glutathione (GSH), and other sulfur molecules, which produce neuroprotective effects in neurological conditions. We previously reported a disruption of microglial CBS/H2S signaling in a Parkinson's disease (PD) mouse model. Yet, it remains unclear whether CBS affects nucleotide-binding oligomerization domain, leucine-rich repeat and pyrin domain-containing 3 (NLRP3) inflammasome activity and other pathologies in PD. Results: Microglial CBS expression decreased after lipopolysaccharide (LPS) stimulation. Elevated GSSG (the oxidized GSH) content and decreased H2S generation were found in the brains of microglial cbs conditional-knockout (cbscKO) mice, whereas serum and brain Hcy levels remained unaltered. Moreover, microglial cbscKO mice were susceptible to NLRP3 inflammasome activation and dopaminergic neuron losses caused by LPS injection into the substantia nigra, whereas cbs overexpression or activation produced opposite effects. In vitro studies showed that cbs overexpression or activation suppressed microglial NLRP3 inflammasome activation and interleukin (IL)-1β secretion by reducing mitochondrial reactive oxygen species (mitoROS) level. Conversely, ablation of cbs enhanced NLRP3 expression and mitoROS generation and augmented microglial NLRP3 inflammasome activity in response to adenosine triphosphate challenge, which was blocked by the mitoROS scavenger. Innovation and Conclusion: The study demonstrated an elevated GSSG level and reduced H2S generation, which correlated with a susceptible status of microglia in the brain of cbscKO mice. Our findings reveal a critical role of CBS in restraining the microglial NLRP3 inflammasome by controlling redox homeostasis and highlight that activation or upregulation of CBS may become a potential strategy for PD treatment.

Metabolic reprogramming and polarization of microglia in Parkinson's disease: Role of inflammasome and iron

Parkinson's disease (PD) is a slowly progressive neurodegenerative disease characterized by α-synuclein aggregation and dopaminergic neuronal death. Recent evidence suggests that neuroinflammation is an early event in the pathogenesis of PD. Microglia are resident immune cells in the central nervous system that can be activated into either pro-inflammatory M1 or anti-inflammatory M2 phenotypes as found in peripheral macrophages. To exert their immune functions, microglia respond to various stimuli, resulting in the flexible regulation of their metabolic pathways. Inflammasomes activation in microglia induces metabolic shift from oxidative phosphorylation to glycolysis, and leads to the polarization of microglia to pro-inflammatory M1 phenotype, finally causing neuroinflammation and neurodegeneration. In addition, iron accumulation induces microglia take an inflammatory and glycolytic phenotype. M2 phenotype microglia is more sensitive to ferroptosis, inhibition of which can attenuate neuroinflammation. Therefore, this review highlights the interplay between microglial polarization and metabolic reprogramming of microglia. Moreover, it will interpret how inflammasomes and iron regulate microglial metabolism and phenotypic shifts, which provides a promising therapeutic target to modulate neuroinflammation and neurodegeneration in PD and other neurodegenerative diseases.

Cyclophilin D in Mitochondrial Dysfunction: A Key Player in Neurodegeneration?

Mitochondrial dysfunction plays a pivotal role in numerous complex diseases. Understanding the molecular mechanisms by which the "powerhouse of the cell" turns into the "factory of death" is an exciting yet challenging task that can unveil new therapeutic targets. The mitochondrial matrix protein CyPD is a peptidylprolyl cis-trans isomerase involved in the regulation of the permeability transition pore (mPTP). The mPTP is a multi-conductance channel in the inner mitochondrial membrane whose dysregulated opening can ultimately lead to cell death and whose involvement in pathology has been extensively documented over the past few decades. Moreover, several mPTP-independent CyPD interactions have been identified, indicating that CyPD could be involved in the fine regulation of several biochemical pathways. To further enrich the picture, CyPD undergoes several post-translational modifications that regulate both its activity and interaction with its clients. Here, we will dissect what is currently known about CyPD and critically review the most recent literature about its involvement in neurodegenerative disorders, focusing on Alzheimer's Disease and Parkinson's Disease, supporting the notion that CyPD could serve as a promising therapeutic target for the treatment of such conditions. Notably, significant efforts have been made to develop CyPD-specific inhibitors, which hold promise for the treatment of such complex disorders.

Coumarin-chalcone hybrid LM-021 and indole derivative NC009-1 targeting inflammation and oxidative stress to protect BE(2)-M17 cells against α-synuclein toxicity

Parkinson's disease (PD) is featured mainly by the loss of dopaminergic neurons and the presence of α-synuclein-containing aggregates in the substantia nigra of brain. The α-synuclein fibrils and aggregates lead to increased oxidative stress and neural toxicity in PD. Chronic inflammation mediated by microglia is one of the hallmarks of PD pathophysiology. In this report, we showed that coumarin-chalcone hybrid LM-021 and indole derivative NC009-1 reduced the expression of major histocompatibility complex-II, NLR family pyrin domain containing (NLRP) 3, caspase-1, inducible nitric oxide synthase, interleukin (IL)-1β, IL-6, and tumor necrosis factor (TNF)-α in α-synuclein-activated mouse BV-2 microglia. Release of pro-inflammatory mediators including nitric oxide, IL-1β, IL-6 and TNF-α was also mitigated. In BE(2)-M17 cells expressing A53T α-synuclein aggregates, LM-021 and NC009-1 reduced α-synuclein aggregation, neuroinflammation, oxidative stress and apoptosis, and promoted neurite outgrowth. These protective effects were mediated by downregulating NLRP1, IL-1β and IL-6, and their downstream pathways including nuclear factor (NF)-κB inhibitor alpha (IκBα)/NF-κB P65 subunit (P65), c-Jun N-terminal kinase (JNK)/proto-oncogene c-Jun (JUN), mitogen-activated protein kinase 14 (P38)/signal transducer and activator of transcription (STAT) 1, and Janus kinase 2 (JAK2)/STAT3. The study results indicate LM-021 and NC009-1 as potential new drug candidates for PD.

NLRP3 mediates the neuroprotective effects of SVHRSP derived from scorpion venom in rotenone-induced experimental Parkinson's disease model

ETHNOPHARMACOLOGICAL RELEVANCE

In traditional Chinese medicine, scorpion is used to treat diseases with symptoms such as trembling, convulsion and dementia. Our laboratory employs patented technology to extract and purify the active single component from scorpion venom. We then utilize mass spectrometry to determine the amino acid sequence of the polypeptide and synthesize it artificially to acquire the polypeptide with a purity of 99.3%, named SVHRSP (Scorpion Venom Heat-Resistant Peptide). SVHRSP has been demonstrated to display potent neuroprotective efficacy in Parkinson's disease.

AIM OF THE STUDY

To explore the molecular mechanisms and potential molecular targets of SVHRSP-afforded neuroprotection in PD mouse models, as well as to investigate the role of NLRP3 in SVHRSP-mediated neuroprotection.

MATERIALS AND METHODS

The PD mouse model was induced by rotenone and the neuroprotective role of SVHRSP on the PD mouse model was measured using the gait test, rotarod test, the number of dopaminergic neurons, and the activation of microglia. RNA sequencing and GSEA analysis were performed to find the differentially biological pathways regulated by SVHRSP. Primary mid-brain neuron-glial cultures and NLRP3-/- mice were applied to verify the role of NLRP3 by using qRT-PCR, western blotting, enzyme-linked immunosorbent assay (ELISA) and immunostaining.

RESULTS

SVHRSP-afforded dopaminergic neuroprotection was accompanied with inhibition of microglia-mediated neuroinflammatory pathways. Importantly, depletion of microglia markedly reduced the neuroprotective efficacy of SVHRSP against rotenone-induced dopaminergic neurotoxicity in vitro. SVHRSP inhibited microglial NOD-like receptor pathway, mRNA expression and protein level of NLRP3 in rotenone PD mice. SVHRSP also reduced rotenone-induced caspse-1 activation and IL-1β maturation, indicating that SVHRSP mitigated activation of NLRP3 inflammasome. Moreover, inactivation of NLRP3 inflammasome by MCC950 or genetic deletion of NLRP3 almost abolished SVHRSP-afforded anti-inflammatory, neuroprotective effects and improvement of motor performance in response to rotenone.

CONCLUSIONS

NLRP3 mediated the neuroprotective effects of SVHRSP in rotenone-induced experimental PD model, providing additional evidence for the mechanisms of SVHRSP-afforded anti-inflammatory and neuroprotective effects in PD.