MPTP-induced Parkinson's Disease Mice Research Articles

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.

Regulatory mechanism of miR-20a-5p in neuronal damage and inflammation in lipopolysaccharide-induced BV2 cells and MPTP-HCl-induced Parkinson's disease mice.

Parkinson's disease (PD) is a prevailing neurodegenerative disorder increasingly affecting the elderly population. The involvement of microRNAs (miRNAs) in PD has been confirmed. We sought to explore the molecular mechanism of miR-20a-5p in PD. Lipopolysaccharide (LPS)-induced BV2 cell model and 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine hydrochloride (MPTP-HCl)-induced PD mouse model were established. miR-20a-5p, inducible nitric oxide synthase (iNOS), interleukin (IL)-6, tumour necrosis factor (TNF)-α, transforming growth factor (TGF)-β1, and IL-10 expression in BV2 cells was examined by reverse transcription - quantitative polymerase chain reaction. Cell viability was assessed by MTT assay. The apoptotic rate and levels of Bcl-2, Bax, cleaved caspase-3, and signal transducer and activator of transmission (STAT)3 were examined by flow cytometry and Western blot. Bioinformatics software predicted the potential binding sites of miR-20a-5p and STAT3. Dual-luciferase experiment verified the binding relationship. Iba1-positive and tyrosine hydroxylase (TH)-positive cell numbers in substantia nigra pars compacta were detected by immunohistochemistry. The effect of miR-20a-5p on motor function in MPTP-induced PD mice was detected by Rota-rod test, Pole test, Traction test and Beam-crossing task. miR-20a-5p was under-expressed in LPS-induced BV2 cells. Overexpression of miR-20a-5p increased the viability of LPS-induced BV2 cells and reduced apoptosis rates. Moreover, overexpression of miR-20a-5p reduced cleaved caspase-3, Bax, iNOS, IL-6, and TNF-α and increased Bcl-2 and TGF-β1, and IL-10. miR-20a-5p targeted STAT3. STAT3 overexpression partially reversed miR-20a-5p overexpression-mediated effects on LPS-induced BV2 cell viability, apoptosis, and inflammatory responses. miR-20a-5p overexpression inhibited MPTP-induced STAT3 and α-synuclein levels, microglia activation, and inflammatory response, and reduced the loss of TH-positive cells in mice. miR-20a-5p overexpression ameliorated MPTP-induced dyskinesia in PD model mice. miR-20a-5p alleviates neuronal damage and suppresses inflammation by targeting STAT3 in PD.

Plasminogen degrades α-synuclein, Tau and TDP-43 and decreases dopaminergic neurodegeneration in mouse models of Parkinson’s disease

Parkinson's disease (PD) is the second most frequently diagnosed neurodegenerative disease, and it is characterized by the intracellular and extracellular accumulation of α-synuclein (α-syn) and Tau, which are major components of cytosolic protein inclusions called Lewy bodies, in the brain. Currently, there is a lack of effective methods that preventing PD progression. It has been suggested that the plasminogen activation system, which is a major extracellular proteolysis system, is involved in PD pathogenesis. We investigated the functional roles of plasminogen in vitro in an okadaic acid-induced Tau hyperphosphorylation NSC34 cell model, ex vivo using brains from normal controls and methyl-4-phenyl-1,2,3,6-tetrahydropyridine (MPTP)-treated mice, and in vivo in a widely used MPTP-induced PD mouse model and an α-syn overexpression mouse model. The in vitro, ex vivo and in vivo results showed that the administered plasminogen crossed the blood‒brain barrier (BBB), entered cells, and migrated to the nucleus, increased plasmin activity intracellularly, bound to α-syn through lysine binding sites, significantly promoted α-syn, Tau and TDP-43 clearance intracellularly and even intranuclearly in the brain, decreased dopaminergic neurodegeneration and increased the tyrosine hydroxylase levels in the substantia nigra and striatum, and improved motor function in PD mouse models. These findings indicate that plasminogen plays a wide range of pivotal protective roles in PD and therefore may be a promising drug candidate for PD treatment.

Human Nasal Inferior Turbinate-Derived Neural Stem Cells Improve the Niche of Substantia Nigra Par Compacta in a Parkinson's Disease Model by Modulating Hippo Signaling.

Parkinson's disease (PD) is one of the most prevalent neurodegenerative diseases, following Alzheimer's disease. The onset of PD is characterized by the loss of dopaminergic neurons in the substantia nigra. Stem cell therapy has great potential for the treatment of neurodegenerative diseases, and human nasal turbinate-derived stem cells (hNTSCs) have been found to share some characteristics with mesenchymal stem cells. Although the Hippo signaling pathway was originally thought to regulate cell size in organs, recent studies have shown that it can also control inflammation in neural cells. Dopaminergic neuron-like cells were differentiated from SH-SY5Y cells (DA-Like cells) and treated with 1-Methyl-4-phenylpyridinium iodide to stimulate Reactive oxidative species (ROS) production. A transwell assay was conducted to validate the effect of hNTSCs on the Hippo pathway. We generated an MPTP-induced PD mouse model and transplanted hNTSCs into the substantia nigra of PD mice via stereotaxic surgery. After five weeks of behavioral testing, the brain samples were validated by immunoblotting and immunostaining to confirm the niche control of hNTSCs. In-vitro experiments showed that hNTSCs significantly increased cell survival and exerted anti-inflammatory effects by controlling ROS-mediated ER stress and hippocampal signaling pathway factors. Similarly, the in-vivo experiments demonstrated an increase in anti-inflammatory effects and cell survival rate. After transplantation of hNTSCs, the PD mouse model showed improved mobility and relief from PD symptoms. hNTSCs improved the survival rate of dopaminergic neurons by manipulating the hippocampal pathway through Yes-associated protein (YAP)/transcriptional coactivator with a PDZ-binding motif (TAZ) by reducing inflammatory cytokines. In this study, we found that controlling the niche of hNTSCs had a therapeutic effect on PD lesions.

Mitochondrial transplantation exhibits neuroprotective effects and improves behavioral deficits in an animal model of Parkinson's disease

Mitochondria are essential organelles for cell survival that manage the cellular energy supply by producing ATP. Mitochondrial dysfunction is associated with various human diseases, including metabolic syndromes, aging, and neurodegenerative diseases. Among the diseases related to mitochondrial dysfunction, Parkinson's disease (PD) is the second most common neurodegenerative disease and is characterized by dopaminergic neuronal loss and neuroinflammation. Recently, it was reported that mitochondrial transfer between cells occurred naturally and that exogenous mitochondrial transplantation was beneficial for treating mitochondrial dysfunction. The current study aimed to investigate the therapeutic effect of mitochondrial transfer on PD in vitro and in vivo. The results showed that PN-101 mitochondria isolated from human mesenchymal stem cells exhibited a neuroprotective effect against 1-methyl-4-phenylpyridinium, 6-hydroxydopamine and rotenone in dopaminergic cells and ameliorated dopaminergic neuronal loss in the brains of C57BL/6J mice injected 30 ​mg/kg of methyl-4-phenyl-1,2,3,6-tetrahydropyridine (MPTP) intraperitoneally. In addition, PN-101 exhibited anti-inflammatory effects by reducing the expression of pro-inflammatory cytokines in microglial cells and suppressing microglial activation in the striatum. Furthermore, intravenous mitochondrial treatment was associated with behavioral improvements during the pole test and rotarod test in the MPTP-induced PD mice. These dual effects of neuroprotection and anti-neuroinflammation support the potential for mitochondrial transplantation as a novel therapeutic strategy for PD.

Inhibition of calcium-sensing receptor by its antagonist promotes gastrointestinal motility in a Parkinson’s disease mouse model

BackgroundThe Calcium-sensing receptor (CaSR) participates in the regulation of gastrointestinal (GI) motility under normal conditions and might be involved in the regulation of GI dysmotility in patients with Parkinson's disease (PD). MethodsCaSR antagonist-NPS-2143 was applied in in vivo and ex vivo experiments to study the effect and underlying mechanisms of CaSR inhibition on GI dysmotility in the MPTP-induced PD mouse model. FindingsOral intake of NPS-2143 promoted GI motility in PD mice as shown by the increased gastric emptying rate and shortened whole gut transit time together with improved weight and water content in the feces of PD mice, and the lack of influence on normal mice. Meanwhile, the number of cholinergic neurons, the proportion of serotonergic neurons, as well as the levels of acetylcholine and serotonin increased, but the numbers of nitrergic and tyrosine hydroxylase immunoreactive neurons, and the levels of nitric oxide synthase and dopamine decreased in the myenteric plexus in the gastric antrum and colon of PD mice in response to NPS-2143 treatment. Furthermore, the numbers of c-fos positive neurons in the nucleus tractus solitarius (NTS) and cholinergic neurons in the dorsal motor nucleus of the vagus (DMV) increased in NPS-2143 treated PD mice, suggesting the involvement of both the enteric (ENS) and central (CNS) nervous systems. However, ex vivo results showed that NPS-2143 directly inhibited the contractility of antral and colonic strips in PD mice via a non-ENS mediated mechanism. Further studies revealed that NPS-2143 directly inhibited the voltage gated Ca2+ channels, which might, at least in part, explain its direct inhibitory effects on the GI muscle strips. InterpretationCaSR inhibition by its antagonist ameliorated GI dysmotility in PD mice via coordinated neuronal regulation by both ENS and CNS in vivo, although the direct effects of CaSR inhibition on GI muscle strips were suppressive.

Neuroprotective effects of cordycepin on MPTP-induced Parkinson's disease mice via suppressing PI3K/AKT/mTOR and MAPK-mediated neuroinflammation

Parkinson's disease (PD) is a prevalent progressive and multifactorial neurodegenerative disorder. Cordycepin is known to exhibit antitumor, anti-inflammatory, antioxidative stress, and neuroprotective effects; however, few studies have explored the neuroprotective mechanism of cordycepin in PD. Using a 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine (MPTP)-induced mouse model, we investigated the impact of cordycepin on PD and its underlying molecular mechanisms. The findings indicated that cordycepin significantly mitigated MPTP-induced behavior disorder and neuroapoptosis, diminished the loss of dopaminergic neurons in the striatum–substantia nigra pathway, elevated striatal monoamine levels and its metabolites, and inhibited the polarization of microglia and the expression of pro-inflammatory factors. Subsequent proteomic and phosphoproteomic analyses revealed the involvement of the MAPK, mTOR, and PI3K/AKT signaling pathways in the protective mechanism of cordycepin. Cordycepin treatment inhibited the activation of the PI3K/AKT/mTOR signaling pathway and enhanced the expression of autophagy proteins in the striatum and substantia nigra. We also demonstrated the in vivo inhibition of the ERK/JNK signaling pathway by cordycepin treatment. In summary, our investigation reveals that cordycepin exerts neuroprotective effects against PD by promoting autophagy and suppressing neuroinflammation and neuronal apoptosis by inhibiting the PI3K/AKT/mTOR and ERK/JNK signaling pathways. This finding highlights the favorable characteristics of cordycepin in neuroprotection and provides novel molecular insights into the neuroprotective role of natural products in PD.

Imperatorin inhibits oxidative stress injury and neuroinflammation via the PI3K/AKT signaling pathway in the MPTP-induced Parkinson's disease mouse.

Parkinson's disease (PD) is a disorder of neurodegeneration. Imperatorin is an active natural furocoumarin characterized by antioxidant, anti-inflammatory, and potent vasodilatory properties. Therefore, we aimed to investigate the biological functions of imperatorin and its mechanisms against PD progression. C57BL/6 mice were intraperitoneally injected with 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine (MPTP; 30 mg/kg) daily for 5 consecutive days to mimic PD conditions in vivo. The MPTP-induced PD model mice were intraperitoneally injected with imperatorin (5 mg/kg) for 25 consecutive days after MPTP administration. The motor and cognitive functions of mice were examined by rotarod test, hanging test, narrow beam test and Morris water maze test. After analysis of MWM test, the expression levels of tyrosine hydroxylase and Iba-1 in the substantia nigra pars compacta were measured by immunohistochemistry staining, immunofluorescence staining and western blotting. The expression levels of striatal dopamine and its metabolite 3,4-dihydroxyphenylacetic acid were also measured. The protein levels of inducible nitric-oxide synthase, cyclooxygenase-2, phosphorylated phosphatidylinositol 3-kinase (PI3K) and phosphorylated protein kinase B (Akt) in the mouse striatum were estimated by western blotting. The expression levels of proinflammatory cytokines including tumor necrosis factor, interleukin (IL)-1β and IL-6 in the mouse striatum were measured by ELISA kits. The expression levels of superoxide dismutase, malondialdehyde and glutathione in the mouse midbrains were measured with commercially available kits. TUNEL staining was performed to identify the apoptosis of midbrain cells. Histopathologic changes in the mouse striata were assessed by hematoxylin-eosin staining. Imperatorin treatment markedly improved spatial learning and memory abilities of MPTP-induced PD mice. The MPTP-induced dopaminergic neuron loss in the mouse striata was inhibited by imperatorin. Imperatorin also suppressed neuroinflammation and neuronal oxidative stress in the midbrains of MPTP-induced PD mice. Mechanistically, imperatorin treatment inhibited the MPTP-induced reduction in the PI3K/Akt pathway. Imperatorin treatment can prevent dopaminergic neuron degeneration and improve cognitive functions via its potent antioxidant and anti-inflammatory properties in an MPTP-induced PD model in mice by regulating the PI3K/Akt pathway.

Secretory Clusterin Inhibits Dopamine Neuron Apoptosis in MPTP Mice by Preserving Autophagy Activity

Secretory clusterin (sCLU) plays an important role in the research progress of nervous system diseases. However, the physiological function of sCLU in Parkinson's disease (PD) are unclear. The purpose of this study was to examine the effects of sCLU-mediated autophagy on cell survival and apoptosis inhibition in a 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine (MPTP)-induced mouse model of PD. We found that MPTP administration induced prolonged pole-climbing time, shortened traction time and rotarod time, significantly decreased TH protein expression in the SN tissue of mice. In contrast, sCLU -treated mice took less time to climb the pole and had an extended traction time and rotating rod time. Meanwhile, sCLU intervention induced increased expression of the TH protein in the SN of mice. These results indicated that sCLU intervention could reduce the loss of dopamine neurons in the SN area and alleviate dyskinesia in mice. Furthermore, MPTP led to suppressed viability, enhanced apoptosis, an increased Bax/Bcl-2 ratio, and cleaved caspase-3 in the SN of mice, and these effects were abrogated by sCLU intervention. In addition, MPTP increased the levels of P62 protein, decreased Beclin1 protein, decreased the ratio of LC3B-II/LC3B-I, and decreased the numbers of autophagosomes and autophagolysosomes in the SN tissues of mice. These effects were also abrogated by sCLU intervention. Activation of PI3K/AKT/mTOR signaling with MPTP inhibited autophagy in the SN of MPTP mice; however, sCLU treatment activated autophagy in MPTP-induced PD mice by inhibiting PI3K/AKT/mTOR signaling. These data indicated that sCLU treatment had a neuroprotective effect in an MPTP-induced model of PD.

Cath-KP, a novel peptide derived from frog skin, prevents oxidative stress damage in a Parkinson's disease model.

Parkinson's disease (PD) is a neurodegenerative condition that results in dyskinesia, with oxidative stress playing a pivotal role in its progression. Antioxidant peptides may thus present therapeutic potential for PD. In this study, a novel cathelicidin peptide (Cath-KP; GCSGRFCNLFNNRRPGRLTLIHRPGGDKRTSTGLIYV) was identified from the skin of the Asiatic painted frog ( Kaloula pulchra). Structural analysis using circular dichroism and homology modeling revealed a unique αββ conformation for Cath-KP. In vitro experiments, including free radical scavenging and ferric-reducing antioxidant analyses, confirmed its antioxidant properties. Using the 1-methyl-4-phenylpyridinium ion (MPP +)-induced dopamine cell line and 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine (MPTP)-induced PD mice, Cath-KP was found to penetrate cells and reach deep brain tissues, resulting in improved MPP +-induced cell viability and reduced oxidative stress-induced damage by promoting antioxidant enzyme expression and alleviating mitochondrial and intracellular reactive oxygen species accumulation through Sirtuin-1 (Sirt1)/Nuclear factor erythroid 2-related factor 2 (Nrf2) pathway activation. Both focal adhesion kinase (FAK) and p38 were also identified as regulatory elements. In the MPTP-induced PD mice, Cath-KP administration increased the number of tyrosine hydroxylase (TH)-positive neurons, restored TH content, and ameliorated dyskinesia. To the best of our knowledge, this study is the first to report on a cathelicidin peptide demonstrating potent antioxidant and neuroprotective properties in a PD model by targeting oxidative stress. These findings expand the known functions of cathelicidins, and hold promise for the development of therapeutic agents for PD.

The Construction and Validation of a Novel Ferroptosis-Related Gene Signature in Parkinson's Disease.

As a newly discovered regulated cell death mode, ferroptosis is associated with the development of Parkinson's disease (PD) and has attracted much attention. Nonetheless, the relationship between ferroptosis and PD pathogenesis remains unclear. The GSE8397 dataset includes GPL96 and GPL97 platforms. The differential genes were analyzed by immune infiltration and Gene Set Enrichment Analysis (GSEA) (p < 0.05), and differential multiple |logFC| > 1 and weighted gene coexpression network analysis (WGCNA) were used to screen differential expression genes (DEGs). The intersection with 368 ferroptosis-related genes (FRGs) was conducted for gene ontology/Kyoto encyclopedia of gene and genome (GO/KEGG) enrichment analysis, gene expression analysis, correlation analysis, single-cell sequencing analysis, and prognosis analysis (area under the curve, AUC) and to predict relevant miRNAs and construct network diagrams using Cytoscape. The intersection genes of differentially expressed ferroptosis-related genes (DEFRGs) and mitochondrial dysfunction genes were validated in the substantia nigra of MPTP-induced PD mice models by Western blotting and immunohistochemistry, and the protein-binding pocket was predicted using the DoGSiteScorer database. According to the results, the estimated scores were positively correlated with the stromal scores or immune scores in the GPL96 and GPL97 platforms. In the GPL96 platform, the GSEA showed that differential genes were mainly involved in the GnRH signaling pathway, B cell receptor signaling pathway, inositol phosphate metabolism, etc. In the GPL97 platform, the GSEA showed that differential genes were mainly involved in the ubiquitin-mediated proteolysis, axon guidance, Wnt signaling pathway, MAPK signaling pathway, etc. We obtained 26 DEFRGs, including 12 up-regulated genes and 14 down-regulated genes, with good correlation. The area under the prognostic analysis curve (AUC > 0.700) showed a good prognostic ability. We found that they were enriched in different neuronal cells, oligodendrocytes, astrocytes, oligodendrocyte precursor cells, and microglial cells, and their expression scores were positively correlated, and selected genes with an AUC curve ≥0.9 were used to predict miRNA, including miR-214/761/3619-5p, miR-203, miR-204/204b/211, miR-128/128ab, miR-199ab-5p, etc. For the differentially expressed ferroptosis-mitochondrial dysfunction-related genes (DEF-MDRGs) (AR, ISCU, SNCA, and PDK4), in the substantia nigra of mice, compared with the Saline group, the expression of AR and ISCU was decreased (p < 0.05), and the expression of α-Syn and PDK4 was increased (p < 0.05) in the MPTP group. Therapeutic drugs that target SNCA include ABBV-0805, Prasinezumab, Cinpanemab, and Gardenin A. The results of this study suggest that cellular DEF-MDRGs might play an important role in PD. AR, ISCU, SNCA, and PDK4 have the potential to be specific biomarkers for the early diagnosis of PD.

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.

Metabolomic analysis of serum short-chain fatty acid concentrations in a mouse of MPTP-induced Parkinson's disease after dietary supplementation with branched-chain amino acids.

The gut microbiota and microbial metabolites influence the enteric nervous system and the central nervous system via the microbial-gut-brain axis. Increasing body of evidence suggests that disturbances in the metabolism of peripheral branched-chain amino acids (BCAAs) can contribute to the development of neurodegenerative diseases through neuroinflammatory signaling. Preliminary research has shown that longitudinal changes in serum amino acid levels in mouse models of Parkinson's disease (PD) are negatively correlated with disease progression. Therefore, the aim of the present study was to determine the changes in serum levels of short-chain fatty acids (SCFAs) in a mouse model of 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine (MPTP)-induced PD after dietary BCAA supplementation. In our research, gas chromatography-mass spectrometry was used to detect serum SCFA concentrations. The data were then analyzed with principal component analysis and orthogonal partial least squares discriminant analysis. Finally, the correlations of serum SCFA levels with gut and motor function in MPTP-induced PD mice were explored. Propionic acid, acetic acid, butyric acid, and isobutyric acid concentrations were elevated in MPTP + H-BCAA mice compared with MPTP mice. Propionic acid concentration was increased the most, while the isovaleric acid concentration was decreased. Propionic acid concentration was positively correlated with fecal weight and water content and negatively correlated with the pole-climbing duration. In conclusion, these results not only suggest that propionic acid may be a potential biomarker for PD, but also indicate the possibility that PD may be treated by altering circulating levels of SCFA.

MiR-100a-5p-enriched exosomes derived from mesenchymal stem cells enhance the anti-oxidant effect in a Parkinson’s disease model via regulation of Nox4/ROS/Nrf2 signaling

BackgroundThe pathogenesis of Parkinson's disease (PD) has not been fully elucidated, and there are no effective disease-modifying drugs for the treatment of PD. Mesenchymal stem cells have been used to treat several diseases, but are not readily available.MethodsHere, we used phenotypically uniform trophoblast stage-derived mesenchymal stem cells (T-MSCs) from embryonic stem cells, which are capable of stable production, and their exosomes (T-MSCs-Exo) to explore the molecular mechanisms involved in dopaminergic (DA) neuron protection in PD models using experimental assays (e.g., western blotting, immunofluorescence and immunohistochemistry staining).ResultsWe assessed the levels of DA neuron injury and oxidative stress in MPTP-induced PD mice and MPP+-induced MN9D cells after treating them with T-MSCs or T-MSCs-Exo. Furthermore, T-MSCs-Exo miRNA sequencing analysis revealed that miR-100-5p-enriched T-MSCs-Exo directly targeted the 3′ UTR of NOX4, which could protect against the loss of DA neurons, maintain nigro-striatal system function, ameliorate motor deficits, and reduce oxidative stress via the Nox4-ROS-Nrf2 axis in PD models.ConclusionsThe study suggests that miR-100-5p-enriched T-MSCs-Exo may be a promising biological agent for the treatment of PD.Graphical Schematic summary of the mechanism underlying the neuroprotective actions of T-MSCs-Exo in PD. T-MSCs Exo may inhibit the expression level of the target gene NOX4 by delivering miR-100-5p, thereby reducing ROS production and alleviating oxidative stress via the Nox4-ROS-Nrf2 axis, thus improving DA neuron damage in PD.

Alpha-Synuclein-Specific Regulatory T Cells Ameliorate Parkinson's Disease Progression in Mice.

Parkinson's disease (PD) is a long-term neurodegenerative disease characterized by dopaminergic neuronal loss and the aggregation of alpha-synuclein (α-syn) in the brain. Cell therapy using regulatory T cells (Tregs) has therapeutic potential on PD progression in a mouse model; however, several challenges were associated with its applications. Here, we propose a strategy for α-syn specific Treg expansion (α-syn Treg). We presented α-syn to T cells via dendritic cells. This method increased the mobility of Tregs towards the site of abundant α-syn in vitro (p < 0.01; α-syn Tregs versus polyclonal Tregs (poly Tregs)) and in vivo. Consequently, α-syn Tregs showed noteworthy neuroprotective effects against motor function deficits (p < 0.05, p < 0.01; α-syn Tregs versus poly Tregs), dopaminergic neuronal loss (p < 0.001; α-syn Tregs versus poly Tregs), and α-syn accumulation (p < 0.05; α-syn Tregs versus poly Tregs) in MPTP-induced PD mice. Furthermore, the adoptive transfer of α-syn Tregs exerted immunosuppressive effects on activated microglia, especially pro-inflammatory microglia, in PD mice. Our findings suggest that α-syn presentation may provide a significant improvement in neuroprotective activities of Tregs and suggest the effective clinical application of Treg therapy in PD.

5-HT4 Receptor is Protective for MPTP-induced Parkinson's Disease Mice Via Altering Gastrointestinal Motility or Gut Microbiota.

Serotonergic dysfunction is related to both motor and nonmotor symptoms in Parkinson's disease (PD). As a 5-HT receptor, 5-HT4 receptor (5-HT4R) is well-studied and already-used in clinical therapy of constipation, which is a typical non-motor symptom in PD. In this study, we investigated the role of 5-HT4R as a regulator of gut function in MPTP-induced acute PD mice model. Daily intraperitoneal injection of GR 125487 (5-HT4R antagonist) was administered 3 days before MPTP treatment until sacrifice. Seven days post-MPTP treatment, feces were collected and gastrointestinal transit time (GITT) was measured, 8 days post-MPTP treatment, behavioral tests were performed, and then animals were sacrificed for the further analysis. We found GR 125487 pretreatment not only increased GITT, but also aggravated MPTP-induced motor bradykinesia. In addition, GR 125487 pretreatment exacerbated the loss of dopaminergic neurons probably by suppressing JAK2/PKA/CREB signaling pathway and increased reactive glia and neuroinflammation in the striatum. 16S rRNA sequencing of fecal microbiota showed that GR 125487 pretreatment altered the composition of gut microbiota, in which the abundance of Akkermansia muciniphila and Clostridium clostridioforme was increased, whereas that of Parabacteroides distasonis and Bacteroides fragilis was decreased, which are closely associated with inflammation condition. Taken together, we demonstrated that GR 125487 pretreatment exacerbates MPTP-induced striatal neurodegenerative processes possibly via the JAK2/PKA/CREB pathway and neuroinflammation by altering gut microbiota composition. In the microbiota-gut-brain axis of PD, 5-HT4R should be further explored and might serve as a target for PD diagnosis and treatment.

NRF1 mitigates motor dysfunction and dopamine neuron degeneration in mice with Parkinson's disease by promoting GLRX m6 A methylation through upregulation of METTL3 transcription.

The feature of Parkinson's disease (PD) is the heavy dopaminergic neuron loss of substantia nigra pars compacta (SNpc), while glutaredoxin (GLRX) has been discovered to modulate the death of dopaminergic neurons. In this context, this study was implemented to uncover the impact of GRX1 on motor dysfunction and dopamine neuron degeneration in PD mice and its potential mechanism. A PD mouse model was established via injection with 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine (MPTP) into mice. After gain- and loss-of-function assays in mice, motor coordination was assessed using rotarod, pole, and open-field tests, and neurodegeneration in mouse SNpc tissues was determined using immunohistochemistry of tyrosine hydroxylase and Nissl staining. NRF1, methyltransferase-like 3 (METTL3), and GLRX expression in SNpc tissues were evaluated using qRT-PCR, Western blot, and immunohistochemistry. The N6-methyladenosine (m6 A) levels of GLRX mRNA were examined using MeRIP. The relationship among NRF1, METTL3, and GLRX was determined by RIP, ChIP, and dual luciferase assays. Low GLRX, METTL3, and NRF1 expression were observed in MPTP-induced mice, accompanied by decreased m6 A modification level of GLRX mRNA. GLRX overexpression alleviated motor dysfunction and dopamine neuron degeneration in MPTP-induced mice. METTL3 promoted m6 A modification and IGF2BP2-dependent stability of GLRX mRNA, and NRF1 increased METTL3 expression by binding to METTL3 promoter. NRF1 overexpression increased m6 A modification of GLRX mRNA and repressed motor dysfunction and dopamine neuron degeneration in MPTP-induced mice, which was counteracted by METTL3 knockdown. Conclusively, NRF1 constrained motor dysfunction and dopamine neuron degeneration in MPTP-induced PD mice by activating the METTL3/GLRX axis.

Compound Dihuang Granule Changes Gut Microbiota of MPTP-Induced Parkinson's Disease Mice via Inhibiting TLR4/NF-κB Signaling.

Intestinal microbiota was connected to Parkinson's Disease (PD) pathology. The ancient Chinese medication for PD is Compound Dihuang Granule (CDG), and we found a neuroprotective function in treating the constipation of PD patients. Nevertheless, the mechanism of action still needs to be clarified. We predicted the probable targets of CDG against PD through Traditional Chinese medicine (TCM) network pharmacology and verified the analysis through animal experiments in vivo. The protein-protein interaction (PPI) network analysis screened PD-related genes, including Toll-like receptor 4(TLR4), TANK-binding kinase 1(TBK1), Nuclear Factor- Kappa B (NF-κB), and Tumor necrosis factor (TNF). Gene Ontology (GO) and Kyoto Encyclopedia of Genes and Genomes (KEGG) analyses proved that the NF-κB and toll-like receptor signaling pathways serve a key function in CDG therapy of PD. Molecular docking analysis demonstrated that CDG strongly connected to TLR4/NF-κB. Experiments findings indicated that CDG improved the damage of dopaminergic neurons and gut microbial dysbiosis, ameliorated motor impairments, and suppressed the PD-associated inflammation and oxidative stress in mice induced by 1-methyl-4-phenyl-1,2,3,6-tetrahy dropyridine (MPTP). CDG suppressed the inflammatory proteins in the colon and protected the intestinal barrier. Overall, CDG improved gut microbial in PD by blocking the pathway of TLR4/NF-κB.

Wuzi Yanzong Pill relieves MPTP-induced motor dysfunction and neuron loss by inhibiting NLRP3 inflammasome-mediated neuroinflammation.

Parkinson disease (PD) is an age-related neurodegenerative disease, which is associated with the loss of dopaminergic neurons (DA neurons) in the substantia nigra pars compacta (SNpc), and neuroinflammation may lead to the occurrence of PD. Wuzi Yanzong Pill (WYP) has demonstrated neuroprotective and anti-inflammatory properties, but its molecular mechanism of action is still unclear. In this study, we used 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine (MPTP)-induced PD mice and LPS-mediated BV2 microglia to explore WYP intervention, anti-inflammatory effect and molecular mechanism in vivo and in vitro. The results showed that oral administration of WYP in MPTP-induced PD mice for 2 weeks ameliorated abnormal motor dysfunction, attenuated the loss of TH + neurons in SNpc, protected dopaminergic neurons, and inhibited the activation of microglia in MPTP-induced PD mice and LPS-stimulated BV2 cell. Meanwhile, WYP intervention inhibited the expression of IL-6, TNF-α, Pro-IL-1β, IL-1β, Pro-IL-18, IL-18 and enhanced the expression of IL-10 in the SNpc of PD mice. Simultaneously, WYP intervention inhibited the expression of NLRP3 inflammasome, accompanied by the decrease of the TLR4/MyD88/NF-κB pathway. However, the exact target and interaction of WYP on NLRP3 inflammasome and TLR4/MyD88/NF-κB pathway still needs to be further investigated.

Integrative multilevel exploration of the mechanism by which Er-Zhi-Wan alleviates the Parkinson's disease (PD)-like phenotype in the MPTP-induced PD mouse model

The neuroprotective effects of Er-Zhi-Wan (EZW), a well-known traditional Chinese formulation, in MPTP-induced Parkinson’s disease (PD) models are poorly understood and require evaluation. A model of PD induced by MPTP was used to evaluate the neuroprotective effects of EZW in mice. The underlying pharmacological mechanisms of EZW for the prevention and treatment of PD were then explored using a combination of multilevel databases, network pharmacology, biological experiments, and LCMS/MS. In vivo data showed that pretreatment with EZW can be neuroprotective against MPTP-induced motor dysfunction and can effectively rescue dopaminergic neurons from MPTP-induced degeneration in mice. Furthermore, data from combined multilevel databases and network pharmacology analysis strategies suggested that the neuroprotective activity of EZW in the treatment of PD is mediated by a complicated multicomponent, multitarget network. Genes such as Grm2, Grm5, Drd2, and Grik2 were identified as important therapeutic targets. Subsequent experimental validation showed that EZW can broadly regulate the mRNA levels of these receptor genes as well as BDNF, and consequently increase the phosphorylation levels of CREB to stimulate CREB signaling. These targets and signaling systems may be responsible for the reversal of neuronal death by EZW after MPTP exposure. The LC-MS/MS results also identified a wide range of chemical components of EZW, including at least 53 precise compounds, further demonstrating the complexity of the network in which EZW exerts its neuroprotective activity. Our work provides evidence for the mechanism of EZW in MPTP-PD models and supports the neuroprotective function of EZW in neurodegenerative diseases.