SIX2-Mediated Microglial M2 Polarization and Exosomal miR-3470b Delivery Protect Dopaminergic Neurons in Parkinson's Disease [EV treatment]
Ontology highlight
ABSTRACT: Parkinson's disease (PD) is characterized by the progressive loss of dopaminergic neurons, with neuroinflammation playing a critical role in disease progression. The transcription factor SIX2 has been identified as an anti-inflammatory factor in microglial cells; however, the underlying mechanisms remain poorly understood. In this study, we demonstrated that SIX2 overexpression protects dopaminergic cells by promoting the polarization of microglial cells from the pro-inflammatory M1 phenotype to the anti-inflammatory M2 phenotype. Mechanistically, SIX2 upregulates DDIT4 expression by binding to its promoter region. DDIT4, in turn, facilitates microglial M2 polarization by inhibiting mTOR, thereby activating autophagy. Furthermore, SIX2-induced M2-polarized microglial cells secrete exosomes carrying miR-3470b. These exosomes are taken up by dopaminergic neurons, where miR-3470b inhibits GREM1 expression and enhances TGF-β signaling activity. Consequently, SIX2-mediated mechanisms prevent and restore damaged dopaminergic neurons in PD mice. Our findings reveal a novel regulatory mechanism of microglial M2 polarization and provide new insights into PD immunotherapy. Additionally, the discovery of exosome-mediated miR-3470b communication between microglia and dopaminergic neurons offers a theoretical foundation for developing exosome-based miRNA therapies.
Project description:Parkinson's disease (PD) is characterized by the progressive loss of dopaminergic neurons, with neuroinflammation playing a critical role in disease progression. The transcription factor SIX2 has been identified as an anti-inflammatory factor in microglial cells; however, the underlying mechanisms remain poorly understood. In this study, we demonstrated that SIX2 overexpression protects dopaminergic cells by promoting the polarization of microglial cells from the pro-inflammatory M1 phenotype to the anti-inflammatory M2 phenotype. Mechanistically, SIX2 upregulates DDIT4 expression by binding to its promoter region. DDIT4, in turn, facilitates microglial M2 polarization by inhibiting mTOR, thereby activating autophagy. Furthermore, SIX2-induced M2-polarized microglial cells secrete exosomes carrying miR-3470b. These exosomes are taken up by dopaminergic neurons, where miR-3470b inhibits GREM1 expression and enhances TGF-β signaling activity. Consequently, SIX2-mediated mechanisms prevent and restore damaged dopaminergic neurons in PD mice. Our findings reveal a novel regulatory mechanism of microglial M2 polarization and provide new insights into PD immunotherapy. Additionally, the discovery of exosome-mediated miR-3470b communication between microglia and dopaminergic neurons offers a theoretical foundation for developing exosome-based miRNA therapies.
Project description:Parkinson's disease is the second most common neurodegenerative disorder, whose characteristic pathology involves progressive loss of dopaminergic neurons and formation of Lewy bodies(LBs) in the substantia nigra(SN). Aggregated and misfolded α-synuclein(α-syn) is the major constituent of LBs. As the newly discovered pathway of renin-angiotensin system (RAS), Angiotensin-(1-7)(Ang-(1-7)) and its receptor Mas have attracted increasing attentions for their correlation with PD progression, but underlying mechanisms remain not very clear. Based on the above, this study established PD models of mice and primary dopaminergic neurons with overexpression of α-syn, then discussed the effect of Ang-(1-7)/Mas on these models combined with downstream lncRNA and miRNA. The findings show that Ang-(1-7) alleviates behavioral disorders, rescues dopaminergic neurons loss and lowers α-syn expression in the SN of hα-syn(A53T) overexpressed PD mice. We also discover that Ang-(1-7) decreases the level of α-syn and apoptosis in the hα-syn(A53T) overexpressed dopaminergic neurons through NEAT1/miR-153-3p axis. Moreover, miR-153-3p expression in peripheral blood is found negatively correlated with that of α-syn. These results not only uncovered the significance and related mechanisms of Ang-(1-7)/Mas on α-syn pathology, but also throwed a new light upon miR-153-3p and NEAT1 as biomarkers and therapeutic targets in PD.
Project description:Systemic inflammatory reactions mediated by chronic infections activate microglia in the central nervous system (CNS) and have been postulated to exacerbate neurodegenerative diseases. We now demonstrate in vivo that repeated systemic challenge of mice with bacterial lipopolysaccharides (LPS) maintains an elevated microglial inflammatory response and triggers neurodegeneration. Repeated chronic intraperitoneal application of LPS over four consecutive days induced loss of dopaminergic neurons in the substantia nigra, a process that was accompanied by decreased levels of dopamine in the striatum. In contrast, total cumulative LPS dose given intraperitoneally within a single acute application did not induce a decrease in dopamine levels nor neurodegeneration. Mice that received repeated systemic LPS application showed increased microglial activation, elevated production of proinflammatory cytokines and activation of the classical complement and its associated phagosome pathway in the brain. Loss of dopaminergic neurons induced by repeated systemic LPS application was rescued in complement C3 deficient mice, confirming an involvement of the complement system in neurodegeneration. Thus, our data demonstrate that repeated systemic exposure to bacterial LPS induces a microglial phagosomal inflammatory response, leading to complement-dependent damage of dopaminergic neurons.
Project description:Parkinson's disease (PD) is a progressive neurodegenerative disorder, which is characterised by degeneration of distinct neuronal populations, including dopaminergic neurons of the substantia nigra. Here, we use a metabolomics profiling approach to identify changes to lipids in PD observed in sebum, a non-invasively available biofluid. We used liquid chromatography-mass spectrometry (LC-MS) to analyse 274 samples from participants (80 drug naïve PD, 138 medicated PD and 56 well matched control subjects) and detected metabolites that could predict PD phenotype. Pathway enrichment analysis shows alterations in lipid metabolism related to the carnitine shuttle, sphingolipid metabolism, arachidonic acid metabolism and fatty acid biosynthesis. This study shows sebum can be used to identify potential biomarkers for PD.
Project description:Brain metastases (BrMs) are the leading cause of death in patients with solid cancers. BrMs exhibit a highly immunosuppressive milieu and poor response to immunotherapies; however, the underlying mechanism remains largely unclear. Here, we show that upregulation of HSP47 in tumor cells drives metastatic colonization and outgrowth in brain by creating an immunosuppressive microenvironment. HSP47-mediated collagen deposition in the metastatic niche promotes microglial polarization to M2 phenotype via the α2β1 integrin/NF-κB pathway, which upregulates the anti-inflammatory cytokines and represses CD8+ T cell anti-tumor responses. Depletion of microglia reverses HSP47-induced inactivation of CD8+ T cells and abolishes brain metastasis. Col003, an inhibitor disrupting HSP47-collagen association restores an anti-tumor immunity and enhances the efficacy of anti-PD-L1 immunotherapy in BrMs-bearing mice. Our study supports that HSP47 is a critical determinant of M2 microglial polarization and immunosuppression, and blocking the HSP47-collagen axis represents a promising therapeutic strategy against brain metastatic tumors.
Project description:Objective: Parkinson's disease (PD) is part of a common type of neurodegenerative disease. AVE0991, a non-peptide analogue of Ang-(1-7), by which the progression of PD has been discovered to be ameliorated, but the specific mechanism whereby AVE0991 modulates the progression of PD remains unclear. Materials and Methods: During the study, the mice overexpressing of human α-syn(A53T) were established to simulate PD pathology, and we also constructed an in vitro model of mouse dopaminergic neurons overexpressing hα-syn(A53T). The [18F] FDG-PET/CT method was also employed to assess FDG uptake in human α-syn(A53T) overexpressing mice. Level of Lnc HOTAIRM1, miR-223-3p were detected via RT-qPCR. Flow cytometry was deployed to assay cell apoptosis. Results: AVE0991 improved behavior disorder and decreased α-syn expression in the substantia nigra in mice with Parkinson's disease. AVE0991 inhibited apoptosis of dopaminergic neurons overexpressing hα-syn(A53T) by LncRNA HOTAIRM1. MiR-223-3p binds to HOTAIRM1 as a ceRNA and directly targets α-syn. Conclusion: The angiotensin-(1–7) analogue AVE0991 targeted the HOTAIRM1/miR-223-3p axis to degrade α-synuclein in PD mice, and showed neuroprotection in vitro.
Project description:Background: Parkinson's disease (PD), a neurodegenerative disease characterised by bradykinesia, rest tremor and rigidit, affects approximately 6.1 million people worldwide. Although its aetiology was attributed to accumulation of misfolded alpha-synuclein species and subsequent loss of dopaminergic neurons in the substantia nigra, recently, systemic factors contributing to its initiation and progression have gained increasing recognition. Specifically, exosomes, a kind of extracellular vesicles in the size range of ∼30 to ∼200 nm, have been highlighted as crucial mediators in orchestrating the intricate intercellular communication in PD. Among its cargos, miRNAs, with its ability to promote target mRNA degradation and inihibit translation, have been identiifed as promising biomarkers and therpaeutic targets. Nonetheless, the effect of anti-parkinsonism medication on the serum exosome miRNA profiles of PD patients remain lagrely unexplored. Objective: To examine the effects of rasagiline, a potentially neuroprotective monoamine oxidase B inihibitor, on the serum exosome miRNA profile of PD patients.
Project description:Background: Parkinson's disease (PD), a neurodegenerative disease characterised by bradykinesia, rest tremor and rigidit, affects approximately 6.1 million people worldwide. Although its aetiology was attributed to accumulation of misfolded alpha-synuclein species and subsequent loss of dopaminergic neurons in the substantia nigra, recently, systemic factors contributing to its initiation and progression have gained increasing recognition. Specifically, exosomes, a kind of extracellular vesicles in the size range of ∼30 to ∼200 nm, have been highlighted as crucial mediators in orchestrating the intricate intercellular communication in PD. Among its cargos, miRNAs, with its ability to promote target mRNA degradation and inihibit translation, have been identiifed as promising biomarkers and therpaeutic targets. Nonetheless, the effect of anti-parkinsonism medication on the serum exosome miRNA profiles of PD patients remain lagrely unexplored. Objective: To examine the effects of rasagiline, a potentially neuroprotective monoamine oxidase B inihibitor, on the serum exosome miRNA profile of PD patients.