Glia Maturation Factor Dependent Inhibition of Mitochondrial PGC-1α Triggers Oxidative Stress-Mediated Apoptosis in N27 Rat Dopaminergic Neuronal Cells

Study insights in the role of PGC-1α in neurological diseases: mechanisms and therapeutic potential

Peroxisome proliferator-activated receptor-γ coactivator-1α (PGC-1α), which is highly expressed in the central nervous system, is known to be involved in the regulation of mitochondrial biosynthesis, metabolic regulation, neuroinflammation, autophagy, and oxidative stress. This knowledge indicates a potential role of PGC-1α in a wide range of functions associated with neurological diseases. There is emerging evidence indicating a protective role of PGC-1α in the pathogenesis of several neurological diseases. As such, a deeper and broader understanding of PGC-1α and its role in neurological diseases is urgently needed. The present review provides a relatively complete overview of the current knowledge on PGC-1α, including its functions in different types of neurons, basic structural characteristics, and its interacting transcription factors. Furthermore, we present the role of PGC-1α in the pathogenesis of various neurological diseases, such as intracerebral hemorrhage, ischemic stroke, Alzheimer's disease, Parkinson's disease, Amyotrophic lateral sclerosis, Huntington's disease, and other PolyQ diseases. Importantly, we discuss some compounds or drug-targeting strategies that have been studied to ameliorate the pathology of these neurological diseases and introduce the possible mechanistic pathways. Based on the available studies, we propose that targeting PGC-1α could serve as a promising novel therapeutic strategy for one or more neurological diseases.

Potential effect of acupuncture on mitochondrial biogenesis, energy metabolism and oxidation stress in MCAO rat via PGC-1α/NRF1/TFAM pathway

PURPOSE

To explore possible mechanism(s) underlying beneficial effects of acupuncture treatment for alleviating focal cerebral infarction-induced neuronal injury, mitochondrial biogenesis, energy metabolism, oxidative stress and dendrite regeneration were evaluated in rats with experimentally induced cerebral ischemia and dendron reperfusion.

MATERIALS AND METHODS

Rats were randomly assigned to three groups (sham-operated, operated group without acupuncture, operated group with acupuncture). RT-PCR and Western blotting were used to assess variations of hippocampal cell mitochondrial DNA (mtDNA) copy number and mRNA and protein expression levels associated with key mitochondrial biogenesis proteins, namely peroxisome proliferator-activated receptor γ coactivator 1α (PGC-1α), nuclear respiration factor 1 (NRF-1) and mitochondrial transcription factor A (TFAM). To evaluate mitochondrial oxidative phosphorylation and respiratory function in ischemic tissues, oxidative phosphorylation protein complex expression levels were assessed via Western blot analysis, mitochondrial membrane potential (MMP) was assessed via confocal microscopy and flow cytometry and adenosine triphosphate (ATP) concentration was assessed using an enzymatic fluorescence-based assay. Immunofluorescence staining was used to evaluate the expression of the neuronal dendron formation marker-Microtubule Associated Protein 2 (MAP2). Additionally, oxidative stress levels were assessed based on superoxide dismutase (SOD) activity, lipid oxidation levels (malondialdehyde, MDA) and glutathione (GSH) levels. Meanwhile, 2,3,5-triphenyltetrazolium chloride (TTC) staining, Nissl staining, transmission electron microscopy observation and neuro behavioral status were used to determine cerebral infarction volume and extent of brain injury.

RESULTS

Acupuncture treatment effectively stimulated mRNA-level and protein-level expression associated with PGC-1α, NRF-1 and TFAM and increased levels of electron transport chain complexes I, IV and V, thereby increasing the ATP concentration, maintaining mitochondrial membrane potential, and promoting dendron regeneration levels. Meanwhile, in hippocampal neurons SOD activity and the glutathione/glutathione disulfide (GSH/GSSG) ratio increased and MDA level decreased.

CONCLUSION

Acupuncture treatment after ischemic injury promoted mitochondrial biogenesis, as reflected by beneficially increased mitochondrial oxidative phosphorylation complex protein levels and brain tissue energy supply, while preventing oxidative stress injury. These results should guide future explorations to elucidate acupuncture-based mechanisms for alleviating neuronal injury triggered by acute cerebral ischemia.

Intranasal Delivery of Mitochondria Attenuates Brain Injury by AMPK and SIRT1/PGC-1α Pathways in a Murine Model of Photothrombotic Stroke

Ischemic stroke is one of the major causes of morbidity and mortality worldwide. Mitochondria play a vital role in the pathological processes of cerebral ischemic injury, but its transplantation and underlying mechanisms remain unclear. In the present study, we examined the effects of mitochondrial therapy on the modulation of AMPK and SIRT1/PGC-1α signaling pathway, oxidative stress, and NLRP3 inflammasome activation after photothrombotic ischemic stroke (pt-MCAO). The adult male mice were subjected to the pt-MCAO in which the proximal-middle cerebral artery was exposed with a 532-nm laser beam for 4 min by retro-orbital injection of a photosensitive dye (Rose Bengal: 15 mg/kg) before the laser light exposure and isolated mitochondria (100 μg protein) were administered intranasally at 30 min, 24 h, and 48 h following post-stroke. After 72 h, mice were tested for neurobehavioral outcomes and euthanized for infarct volume, brain edema, and molecular analysis. First, we found that mitochondria therapy significantly decreased brain infarct volume and brain edema, improved neurological dysfunction, attenuated ischemic stroke-induced oxidative stress, and neuroinflammation. Second, mitochondria treatment inhibited NLRP3 inflammasome activation. Finally, mitochondria therapy accelerated p-AMPKα(Thr172) and PGC-1α expression and resorted SIRT1 protein expression levels in pt-MCAO mice. In conclusion, our results demonstrate that mitochondria therapy exerts neuroprotective effects by inhibiting oxidative damage and inflammation, mainly dependent on the heightening activation of the AMPK and SIRT1/PGC-1α signaling pathway. Thus, intranasal delivery of mitochondria might be considered a new therapeutic strategy for ischemic stroke treatment.

Cellulose ether treatment inhibits amyloid beta aggregation, neuroinflammation and cognitive deficits in transgenic mouse model of Alzheimer's disease

Alzheimer's disease (AD) is an incurable, progressive and devastating neurodegenerative disease. Pathogenesis of AD is associated with the aggregation and accumulation of amyloid beta (Aβ), a major neurotoxic mediator that triggers neuroinflammation and memory impairment. Recently, we found that cellulose ether compounds (CEs) have beneficial effects against prion diseases by inhibiting protein misfolding and replication of prions, which share their replication mechanism with Aβ. CEs are FDA-approved safe additives in foods and pharmaceuticals. Herein, for the first time we determined the therapeutic effects of the representative CE (TC-5RW) in AD using in vitro and in vivo models. Our in vitro studies showed that TC-5RW inhibits Aβ aggregation, as well as neurotoxicity and immunoreactivity in Aβ-exposed human and murine neuroblastoma cells. In in vivo studies, for the first time we observed that single and weekly TC-5RW administration, respectively, improved memory functions of transgenic 5XFAD mouse model of AD. We further demonstrate that TC-5RW treatment of 5XFAD mice significantly inhibited Aβ oligomer and plaque burden and its associated neuroinflammation via regulating astrogliosis, microgliosis and proinflammatory mediator glial maturation factor beta (GMFβ). Additionally, we determined that TC-5RW reduced lipopolysaccharide-induced activated gliosis and GMFβ in vitro. In conclusion, our results demonstrate that CEs have therapeutic effects against Aβ pathologies and cognitive impairments, and direct, potent anti-inflammatory activity to rescue neuroinflammation. Therefore, these FDA-approved compounds are effective candidates for developing therapeutics for AD and related neurodegenerative diseases associated with protein misfolding.

Matrine promotes mitochondrial biosynthesis and reduces oxidative stress in experimental optic neuritis

Optic neuritis (ON), characterized by inflammation of the optic nerve and apoptosis of retinal ganglion cells (RGCs), is one of the leading causes of blindness in patients. Given that RGC, as an energy-intensive cell, is vulnerable to mitochondrial dysfunction, improving mitochondrial function and reducing oxidative stress could protect these cells. Matrine (MAT), an alkaloid derived from Sophoraflavescens, has been shown to regulate immunity and protect neurons in experimental autoimmune encephalomyelitis (EAE), an animal model of multiple sclerosis and ON. However, the protective mechanism of MAT on RGCs is largely unknown. In this study, we show that MAT treatment significantly reduced the degree of inflammatory infiltration and demyelination of the optic nerve and increased the survival rate of RGCs. The expression of Sirtuin 1 (SIRT1), a member of an evolutionarily conserved gene family (sirtuins), was upregulated, as well as its downstream molecules Nrf2 and PGC-1α. The percentage of TOMM20-positive cells was also increased remarkably in RGCs after MAT treatment. Thus, our results indicate that MAT protects RGCs from apoptosis, at least in part, by activating SIRT1 to regulate PGC-1α and Nrf2, which, together, promote mitochondrial biosynthesis and reduce the oxidative stress of RGCs.

Recent advances in the use of CRISPR/Cas for understanding the early development of molecular gaps in glial cells

Glial cells are non-neuronal elements of the nervous system (NS) and play a central role in its development, maturation, and homeostasis. Glial cell interest has increased, leading to the discovery of novel study fields. The CRISPR/Cas system has been widely employed for NS understanding. Its use to study glial cells gives crucial information about their mechanisms and role in the central nervous system (CNS) and neurodegenerative disorders. Furthermore, the increasingly accelerated discovery of genes associated with the multiple implications of glial cells could be studied and complemented with the novel screening methods of high-content and single-cell screens at the genome-scale as Perturb-Seq, CRISP-seq, and CROPseq. Besides, the emerging methods, GESTALT, and LINNAEUS, employed to generate large-scale cell lineage maps have yielded invaluable information about processes involved in neurogenesis. These advances offer new therapeutic approaches to finding critical unanswered questions about glial cells and their fundamental role in the nervous system. Furthermore, they help to better understanding the significance of glial cells and their role in developmental biology.

Covering the Role of PGC-1α in the Nervous System

The peroxisome proliferator-activated receptor-γ coactivator-1α (PGC-1α) is a well-known transcriptional coactivator involved in mitochondrial biogenesis. PGC-1α is implicated in the pathophysiology of many neurodegenerative disorders; therefore, a deep understanding of its functioning in the nervous system may lead to the development of new therapeutic strategies. The central nervous system (CNS)-specific isoforms of PGC-1α have been recently identified, and many functions of PGC-1α are assigned to the particular cell types of the central nervous system. In the mice CNS, deficiency of PGC-1α disturbed viability and functioning of interneurons and dopaminergic neurons, followed by alterations in inhibitory signaling and behavioral dysfunction. Furthermore, in the ALS rodent model, PGC-1α protects upper motoneurons from neurodegeneration. PGC-1α is engaged in the generation of neuromuscular junctions by lower motoneurons, protection of photoreceptors, and reduction in oxidative stress in sensory neurons. Furthermore, in the glial cells, PGC-1α is essential for the maturation and proliferation of astrocytes, myelination by oligodendrocytes, and mitophagy and autophagy of microglia. PGC-1α is also necessary for synaptogenesis in the developing brain and the generation and maintenance of synapses in postnatal life. This review provides an outlook of recent studies on the role of PGC-1α in various cells in the central nervous system.

Comparison of Rat Primary Midbrain Neurons Cultured in DMEM/F12 and Neurobasal Mediums

Introduction:

Midbrain dopaminergic neurons are involved in various brain functions, including motor behavior, reinforcement, motivation, learning, and cognition. Primary dopaminergic neurons and also several lines of these cells are extensively used in cell culture studies. Primary dopaminergic neurons prepared from rodents have been cultured in both DMEM/F12 and neurobasal mediums in several studies. However, there is no document reporting the comparison of these two mediums. So in this study, we evaluated the neurons and astroglial cells in primary midbrain neurons from rat embryos cultured in DMEM/F12 and neurobasal mediums.

Methods:

Primary mesencephalon cells were prepared from the E14.5 rat embryo. Then they were seeded in two different mediums (Dulbecco's Modified Eagle Medium/Nutrient Mixture F-12 [DMEM/F12] and neurobasal). On day 3 and day 5, half of the medium was replaced with a fresh medium. On day 7, β3-tubulin-, GFAP (Glial fibrillary acidic protein)- and Tyrosine Hydroxylase TH-positive cells were characterized as neurons, astrocytes, and dopaminergic neurons, respectively, using immunohistochemistry. Furthermore, the morphology of the cells in both mediums was observed under light microscopy on days 1, 3, and 5.

Results:

The cells cultured in both mediums were similar under light microscopy regarding the cell number, but in a neurobasal medium, the cells have aggregated and formed clustering structures. Although GFAP-immunoreactive cells were lower in neurobasal compared to DMEM/F12, the number of β3-tubulin- and TH-positive cells in both cultures was the same.

Conclusion:

This study’s findings demonstrated that primary midbrain cells from the E14.5 rat embryo could grow in both DMEM/F12 and neurobasal mediums. Therefore, considering the high price of a neurobasal medium, it can be replaced with DMEM/F12 for culturing primary dopaminergic neurons.

Intracellular metabolic reprogramming mediated by micro-RNAs in differentiating and proliferating cells under non-diseased conditions

Intracellular metabolic reprogramming is a critical process the cells carry out to increase biomass, energy fulfillment and genome replication. Cells reprogram their demands from internal catabolic or anabolic activities in coordination with multiple genes and microRNAs which further control the critical processes of differentiation and proliferation. The microRNAs reprogram the metabolism involving mitochondria, the nucleus and the biochemical processes utilizing glucose, amino acids, lipids, and nucleic acids resulting in ATP production. The processes of glycolysis, tricarboxylic acid cycle, or oxidative phosphorylation are also mediated by micro-RNAs maintaining cells and organs in a non-diseased state. Several reports have shown practical applications of metabolic reprogramming for clinical utility to assess various diseases, mostly studying cancer and immune-related disorders. Cells under diseased conditions utilize glycolysis for abnormal growth or proliferation, respectively, affecting mitochondrial paucity and biogenesis. Similar metabolic processes also affect gene expressions and transcriptional regulation for carrying out biochemical reactions. Metabolic reprogramming is equally vital for regulating cell environment to maintain organs and tissues in non-diseased states. This review offers in depth insights and analysis of how miRNAs regulate metabolic reprogramming in four major types of cells undergoing differentiation and proliferation, i.e., immune cells, neuronal cells, skeletal satellite cells, and cardiomyocytes under a non-diseased state. Further, the work systematically summarizes and elaborates regulation of genetic switches by microRNAs through predominantly through cellular reprogramming and metabolic processes for the first time. The observations will lead to a better understanding of disease initiation during the differentiation and proliferation stages of cells, as well as fresh approaches to studying clinical onset of linked metabolic diseases targeting metabolic processes.

Transcriptional Activity of Neurotrophins Genes and Their Receptors in the Peripheral Blood in Patients with Thyroid Diseases in Bukovinian Population of Ukraine

Objective. Thyroid hormone has an especially strong impact on central nervous system development, and thyroid hormone deficiency has been shown to result in severe mental retardation. It is crucial to identify compensatory mechanisms that can be involved in improving cognitive function and the quality of life of patients with hypothyroidism. Methods: We used the pathway-specific PCR array (Neurotrophins and Receptors RT2 Profiler PCR Array, QIAGEN, Germany) to identify and validate neurotrophins genes and their receptor expression in patients with thyroid pathology and control group. Results: The analysis of gene expression of neurotrophins and their receptors showed that CRHBP, FRS2, FRS3, GFRA1, GFRA2, GMFB, NGF, NRG2, NRG4, NTF4, TRO, and VGF significantly decreased their expression in Group 3, which includes the patients with postoperative hypothyroidism. The patients with primary hypothyroidism stemming from AIT had significantly reduced expression of CRHBP, GFRA1, GFRA2, GMFB, NGF, PTGER2, and VGF, while the expression of NRG4 and TRO increased. In Group 3, which includes the patients with AIT and elevated serum anti-Tg and anti-TPO autoantibodies, the mRNA levels of GFRA2, NGF, NRG2, NTF4, NGF, PTGER were reduced, and the expression of CRHBP, FRS2, FRS3 GFRA1, GMFB, NRG4, TRO, and VGF significantly increased. Conclusion: These results indicate significant variability in the transcriptional activity of the genes of encoding neurotrophins and their receptors in the peripheral blood in people with thyroid diseases.

PGC-1ɑ Mediated-EXOG, a Specific Repair Enzyme for Mitochondrial DNA, Plays an Essential Role in the Rotenone-Induced Neurotoxicity of PC12 Cells

Mitochondria harbor small circular genomes (mtDNA) that encode 13 oxidative phosphorylation (OXPHOS) proteins, and types of damage to mtDNA may contribute to neuronal damage. Recent studies suggested that regulation of mtDNA repair proteins may be a potential strategy for treating neuronal damage. The mtDNA repair system contains its own repair enzymes and is independent from the nuclear DNA repair system. Endo/exonuclease G-like(EXOG) is a mitochondria-specific 5-exo/endonuclease required for repairing endogenous single-strand breaks (SSBs) in mtDNA. However, whether EXOG plays a key role in neuronal damage induced by rotenone remains unknown. Thus, in this study, we aimed to investigate the effect of EXOG on mtDNA repair and mitochondrial functional maintenance in rotenone-induced neurotoxicity. Our results indicated that rotenone influenced the expression and location of EXOG in PC12 cells. Meanwhile, after rotenone exposure, the expression was reduced for proteins responsible for mtDNA repair, including DNA polymerase γ (POLG), high-temperature requirement protease A2 (HtrA2), and the heat-shock factor 1-single-stranded DNA-binding protein 1 (HSF1-SSBP1) complex. Further analysis demonstrated that EXOG knockdown led to reduced mtDNA copy number and mtDNA transcript level and increased mtDNA deletion, which further aggravated the mtDNA damage and mitochondrial dysfunction under rotenone stress. In turn, EXOG overexpression protected PC12 cells from mtDNA damage and mitochondrial dysfunction induced by rotenone. As a result, EXOG knockdown reduced cell viability and tyrosine hydroxylase expression, while EXOG overexpression alleviated rotenone's effect on cell viability and tyrosine hydroxylase expression in PC12 cells. Further, we observed that EXOG influenced mtDNA repair by regulating protein expression of the HSF1-SSBP1 complex and POLG. Furthermore, our study showed that PGC-1α upregulation with ZLN005 led to increased protein levels of EXOG, POLG, HSF1, and SSBP1, all of which contribute to mtDNA homeostasis. Therefore, PGC-1α may be involved in mtDNA repair through interacting with multiple mtDNA repair proteins, especially with the help of EXOG. In summary, EXOG regulation by PGC-1α plays an essential role in rotenone-induced neurotoxicity in PC12 cells. EXOG represents a protective effect strategy in PC12 cells exposed to rotenone.

Neuroimmune connections between corticotropin-releasing hormone and mast cells: novel strategies for the treatment of neurodegenerative diseases

Corticotropin-releasing hormone is a critical component of the hypothalamic–pituitary–adrenal axis, which plays a major role in the body’s immune response to stress. Mast cells are both sensors and effectors in the interaction between the nervous and immune systems. As first responders to stress, mast cells can initiate, amplify and prolong neuroimmune responses upon activation. Corticotropin-releasing hormone plays a pivotal role in triggering stress responses and related diseases by acting on its receptors in mast cells. Corticotropin-releasing hormone can stimulate mast cell activation, influence the activation of immune cells by peripheral nerves and modulate neuroimmune interactions. The latest evidence shows that the release of corticotropin-releasing hormone induces the degranulation of mast cells under stress conditions, leading to disruption of the blood-brain barrier, which plays an important role in neurological diseases, such as Alzheimer’s disease, Parkinson’s disease, multiple sclerosis, autism spectrum disorder and amyotrophic lateral sclerosis. Recent studies suggest that stress increases intestinal permeability and disrupts the blood-brain barrier through corticotropin-releasing hormone-mediated activation of mast cells, providing new insight into the complex interplay between the brain and gastrointestinal tract. The neuroimmune target of mast cells is the site at which the corticotropin-releasing hormone directly participates in the inflammatory responses of nerve terminals. In this review, we focus on the neuroimmune connections between corticotropin-releasing hormone and mast cells, with the aim of providing novel potential therapeutic targets for inflammatory, autoimmune and nervous system diseases.

Analysis of the Clinical Diagnostic Value of GMFB in Cerebral Infarction

BACKGROUND

Glial Maturation Factor Beta (GMFB) is a highly conserved brain-enriched protein implicated in immunoregulation, neuroplasticity and apoptosis, processes central to neural injury and repair following cerebral ischaemia. Therefore, we examined if changes in neurocellular GMFB expression and release can be used to assess brain injury following ischaemia.

METHODS AND RESULTS

Immunofluorescence staining, Western blotting, immunohistochemistry and ELISA were used to measure GMFB in cultured neurons and astrocytes, rat brain tissues and plasma samples from stroke model rats and stroke patients, while cell viability assays, TTC staining and micro- PET were used to assess neural cell death and infarct severity. Immunofluorescence and immunohistochemistry revealed GMFB expression mainly in astrocyte and neuronal nuclei but also in neuronal axons and dendrites. Free GMFB concentration increased progressively in the culture medium during hypoxia-hypoglycaemia treatment. Plasma GMFB concentration increased in rats subjected to middle cerebral artery occlusion (MCAO, a model of stroke-reperfusion) and in stroke patients. Plasma GMFB in MCAO model rats was strongly correlated with infarct size (R2=0.9582). Plasma GMFB concentration was also markedly elevated in stroke patients within 24 h of onset and remained elevated for more than one week. Conversely, plasma GMFB elevations were not significant in myocardial infarct patients and stroke patients without infarction.

CONCLUSION

GMFB has the prerequisite stability, expression specificity and response dynamics to serve as a reliable indicator of ischaemic injury in animal models and stroke patients. Plasma GMFB may be a convenient non-invasive adjunct to neuroimaging for stroke diagnosis and prognosis.

Activation of CB1R-Dependent PGC-1α Is Involved in the Improved Mitochondrial Biogenesis Induced by Electroacupuncture Pretreatment

Electroacupuncture (EA) pretreatment induces cerebral ischemic tolerance; however, the mechanism remains poorly understood. This study aimed to determine the participation of peroxisome proliferator-activated receptor γ coactivator-1α (PGC-1α)-mediated mitochondrial biogenesis in the neuroprotection of EA and whether cannabinoid receptor 1 (CB1R) is involved in this mechanism. At 2 hours after EA pretreatment, adult male C57BL/6j mice were subjected to 60-minute right middle cerebral artery occlusion (MCAO). Mitochondrial function, the level of mitochondrial biogenesis-related proteins (nuclear transcription factor 1, NRF1; mitochondrial transcription factor A, TFAM), and mitochondrial DNA (mtDNA) were measured. A small interfering RNA (siRNA) targeting PGC-1α and the CB1R antagonists AM251 and SR141716A were given to the animals before EA pretreatment, and mitochondrial function and biogenesis were examined after MCAO. EA ameliorated the mitochondrial function, upregulated the NRF1 and TFAM expression, and increased the mtDNA levels and the volume and number of mitochondria. EA pretreatment increased the expression of PGC-1α, whereas the PGC-1α siRNA and CB1R antagonists reversed the improved neuroprotection and increased mitochondrial biogenesis induced by EA. Our results indicated that EA pretreatment protects the mitochondria and promotes mitochondrial biogenesis by activating CB1R-dependent PGC-1α, which provides a novel mechanism for EA pretreatment-induced ischemic tolerance.

Glia Maturation Factor (GMF) Regulates Microglial Expression Phenotypes and the Associated Neurological Deficits in a Mouse Model of Traumatic Brain Injury

Traumatic brain injury (TBI) induces inflammatory responses through microglial activation and polarization towards a more inflammatory state that contributes to the deleterious secondary brain injury. Glia maturation factor (GMF) is a pro-inflammatory protein that is responsible for neuroinflammation following insult to the brain, such as in TBI. We hypothesized that the absence of GMF in GMF-knockout (GMF-KO) mice would regulate microglial activation state and the M1/M2 phenotypes following TBI. We used the weight drop model of TBI in C57BL/6 mice wild-type (WT) and GMF-KO mice. Immunofluorescence staining, Western blot, and ELISA assays were performed to confirm TBI-induced histopathological and neuroinflammatory changes. Behavioral analysis was done to check motor coordination ability and cognitive function. We demonstrated that the deletion of GMF in GMF-KO mice significantly limited lesion volume, attenuated neuronal loss, inhibited gliosis, and activated microglia adopted predominantly anti-inflammatory (M2) phenotypes. Using an ELISA method, we found a gradual decrease in pro-inflammatory cytokines (TNF-α and IL-6) and upregulation of anti-inflammatory cytokines (IL-4 and IL-10) in GMF-KO mice compared with WT mice, thus, promoting the transition of microglia towards a more predominantly anti-inflammatory (M2) phenotype. GMF-KO mice showed significant improvement in motor ability, memory, and cognition. Overall, our results demonstrate that GMF deficiency regulates microglial polarization, which ameliorates neuronal injury and behavioral impairments following TBI in mice and concludes that GMF is a regulator of neuroinflammation and an ideal therapeutic target for the treatment of TBI.

Valeriana officinalis Counteracts Rotenone Effects on Spreading Depression in the Rat Brain in vivo and Protects Against Rotenone Cytotoxicity Toward Rat Glioma C6 Cells in vitro

Astrocytes can protect neurons against oxidative stress and excitability-dependent disorders, such as epilepsy. Valeriana officinalis has been used as anticonvulsant and can exert an antioxidant effect, which may underlie its opposing action against the toxic effects of the pesticide rotenone. We investigated the V. officinalis/rotenone interaction in the cortical spreading depression (CSD), a phenomenon that depends upon brain excitability (in vivo model). In addition, we analyzed the protective action of V. officinalis against the cytotoxic effects of rotenone in cultures of rat C6 glioma cells (in vitro model). For the CSD study, Wistar rats received either V. officinalis (250 mg/kg/day via gavage for 15 days; n = 8) or 10 mg/kg/day rotenone via subcutaneous injections for 7 days (n = 7), or they received both substances (n = 5). Two control groups received either saline (vehicle for V. officinalis; n = 8) or 1% Tween-80 aqueous solution (vehicle for rotenone; n = 9). After treatment, CSD was recorded for 4 h. The rotenone- and V. officinalis-treated groups presented, respectively, with lower (2.96 ± 0.14 mm/min), and higher CSD propagation velocity (3.81 ± 0.10 mm/min) when compared with the controls (Tween-80, 3.37 ± 0.06 mm/min and saline, 3.35 ± 0.08 mm/min; p < 0.05). The rotenone plus V. officinalis-treated group displayed a CSD velocity (3.38 ± 0.07 mm/min) that was similar to controls. In line with these results, in vitro experiments on rat glioma C6 cells revealed a protective effect (MTT assay) of V. officinalis against rotenone-induced cytotoxicity. These results suggest the therapeutic potential of V. officinalis for treating neurological diseases involving redox imbalance and astrocyte dysfunction.

A role for glia maturation factor dependent activation of mast cells and microglia in MPTP induced dopamine loss and behavioural deficits in mice

The molecular mechanism mediating degeneration of nigrostriatal dopaminergic neurons in Parkinson's disease (PD) is not yet fully understood. Previously, we have shown the contribution of glia maturation factor (GMF), a proinflammatory protein in dopaminergic neurodegeneration mediated by activation of mast cells (MCs). In this study, methyl-4-phenyl-1,2,3,6-tetrahydropyridine (MPTP)-induced nigrostriatal neurodegeneration and astro-glial activations were determined by western blot and immunofluorescence techniques in wild type (WT) mice, MC-deficient (MC-KO) mice and GMF-deficient (GMF-KO) mice, with or without MC reconstitution before MPTP administration. We show that GMF-KO in the MCs reduces the synergistic effects of MC and Calpain1 (calcium-activated cysteine protease enzyme)-dependent dopaminergic neuronal loss that reduces motor behavioral impairments in MPTP-treated mouse. Administration of MPTP increase in calpain-mediated proteolysis in nigral dopaminergic neurons further resulting in motor decline in mice. We found that MPTP administered WT mice exhibits oxidative stress due to significant increases in the levels of malondialdehyde, superoxide dismutase and reduction in the levels of reduced glutathione and glutathione peroxidase activity as compared with both MC-KO and GMF-KO mice. The number of TH-positive neurons in the ventral tegmental area, substantia nigra and the fibers in the striatum were significantly reduced while granulocyte macrophage colony-stimulating factor (GM-CSF), MC-Tryptase, GFAP, IBA1, Calpain1 and intracellular adhesion molecule 1 expression were significantly increased in WT mice. Similarly, tyrosine hydroxylase, dopamine transporters and vesicular monoamine transporters 2 proteins expression were significantly reduced in the SN of MPTP treated WT mice. The motor behavior as analyzed by rotarod and hang test was significantly reduced in WT mice as compared with both the MC-KO and GMF-KO mice. We conclude that GMF-dependent MC activation enhances the detrimental effect of astro-glial activation-mediated oxidative stress and neuroinflammation in the midbrain, and its inhibition may slowdown the progression of PD.

Immune Suppression of Glia Maturation Factor Reverses Behavioral Impairment, Attenuates Amyloid Plaque Pathology and Neuroinflammation in an Alzheimer's Disease Mouse Model

Alzheimer's disease (AD) is an irreversible progressive neurodegenerative disorder recognized by accumulation of amyloid-plaques (APs) and neurofibrillary tangles (NFTs) and eventually loss of memory. Glia maturation factor (GMF), a neuroinflammatory protein first time isolated and cloned in our laboratory plays an important role in the pathogenesis of AD. However, no studies have been reported on whether anti-GMF antibody administration could downregulate neuroinflammation and attenuate amyloid pathology in AD brain. We investigated the potential effect of single dose of (2 mg/kg b.wt/mouse) intravenously (iv) injected with anti-GMF antibodyon cognitive function, neuroprotection, neuroinflammation and Aβ load in the brain of 9-month-old 5XFAD mice. Following 4 weeks of anti-GMF antibody delivery in mice, we found reduced expression of GMF, astrocytic glial fibrillary acidic protein (GFAP) and microglial ionizing calcium binding adaptor molecule 1 (Iba1) as well as improvement inneuroinflammatory response via inhibition of pro-inflammatory cytokines (TNF-α, IL-1β and IL-6) production and amyloid pathology in the cerebral cortex and hippocampal CA1 region of 5XFAD mice. Correspondingly, blockade of GMF function with anti-GMF antibody improved spatial learning, memory, and long-term recognition memory in 5XFAD mice. The present study demonstrates that the immune checkpoint blockade of GMF function with anti-GMF antibody coordinates anti-inflammatory effects to attenuate neurodegeneration in the cortex and hippocampal CA1 region of 5XFAD mouse brain. Further, our data suggest, that pharmacological immune neutralization of GMF is a promising neuroprotective strategy totherapeutically target neuroinflammation and neurodegeneration in AD. Graphical Abstract 5XFAD mice Polyclonal anti-GMF antibody.

Neuroinflammation Mediated by Glia Maturation Factor Exacerbates Neuronal Injury in an in vitro Model of Traumatic Brain Injury

Traumatic brain injury (TBI) is the primary cause of death and disability affecting over 10 million people in the industrialized world. TBI causes a wide spectrum of secondary molecular and cellular complications in the brain. However, the pathological events are still not yet fully understood. Previously, we have shown that the glia maturation factor (GMF) is a mediator of neuroinflammation in neurodegenerative diseases. To identify the potential molecular pathways accompanying TBI, we used an in vitro cell culture model of TBI. A standardized injury was induced by scalpel cut through a mixed primary cell culture of astrocytes, microglia and neurons obtained from both wild type (WT) and GMF-deficient (GMF-KO) mice. Cell culture medium and whole-cell lysates were collected at 24, 48, and 72 h after the scalpel cuts injury and probed for oxidative stress using immunofluorescence analysis. Results showed that oxidative stress markers such as glutathione and glutathione peroxidase were significantly reduced, while release of cytosolic enzyme lactate dehydrogenase along with nitric oxide and prostaglandin E2 were significantly increased in injured WT cells compared with injured GMF-KO cells. In addition, injured WT cells showed increased levels of oxidation product 4-hydroxynonenal and 8-oxo-2'-deoxyguanosine compared with injured GMF-KO cells. Further, we found that injured WT cells showed a significantly increased expression of glial fibrillary acidic protein, ionized calcium binding adaptor molecule 1, and phosphorylated ezrin/radixin/moesin proteins, and reduced microtubule associated protein expression compared with injured GMF-KO cells after injury. Collectively, our results demonstrate that GMF exacerbates the oxidative stress-mediated neuroinflammation that could be brought about by TBI-induced astroglial activation.

NLRP3 inflammasome and glia maturation factor coordinately regulate neuroinflammation and neuronal loss in MPTP mouse model of Parkinson's disease

Neuroinflammation plays an active role in the pathogenesis of several neurodegenerative diseases, including Parkinson's disease (PD). Earlier studies from this laboratory showed that glia maturation factor (GMF), a proinflammatory mediator; is up-regulated in the brain in neurodegenerative diseases and that deficiency of GMF showed decreased production of IL-1β and improved behavioral abnormalities in mouse model of PD. However, the mechanisms linking GMF and dopaminergic neuronal death have not been completely explored. In the present study, we have investigated the expression of NLRP3 inflammasome and caspase-1 in the substantia nigra (SN) of human PD and non-PD brains by immunohistochemistry. Wild-type (WT) and GMF^-/- (GMF knock-out) mice were treated with 1-methyl-4-phenyl-1,2,3,6-tetrahydro pyridine (MPTP) and the brains were isolated for neurochemical and morphological examinations. NLRP3 and caspase-1 positive cells were found significantly increased in PD when compared to non-PD control brains. Moreover, GMF co-localized with α-Synuclein within reactive astrocytes in the midbrain of PD. Mice treated with MPTP exhibit glial activation-induced inflammation, and nigrostriatal dopaminergic neurodegeneration. Interestingly, increased expression of the inflammasome components in astrocytes and microglia observed in the SN of MPTP-treated WT mice were significantly reduced in GMF^-/- mice. Additionally, we show that NLRP3 activation in microglia leads to translocation of GMF and NLRP3 to the mitochondria. We conclude that downregulation of GMF may have beneficial effects in prevention of PD by modulating the cytotoxic functions of microglia and astrocytes through reduced activation of the NLRP3 inflammasome; a major contributor of neuroinflammation in the CNS.

Bexarotene treatment increases dendritic length in the nucleus accumbens without change in the locomotor activity and memory behaviors, in old mice

The aged brain has biochemical and morphological alterations in the dendrites of the pyramidal neurons of the limbic system, which consequently trigger motor and cognitive deficits. Bexarotene 4-[1-(3,5,5,8,8-pentamethyl-6,7-dihydronaphthalen-2-yl)ethenyl]benzoic acid is a selective agonist of X-retinoid receptors which acts by binding to the intracellular retinoic acid receptors (RAR). It decreases oxidative and inflammatory activity, in addition to the transport of lipids, mechanisms that together could have a neuroprotective effect. Our objective was to evaluate the effect of bexarotene on the motor and cognitive processes, as well as its influence on the dendritic morphology of neurons in the limbic system of elderly mice. Dendritic morphology was evaluated with the Golgi-Cox staining procedure followed by the Sholl analysis. Bexarotene was administered at different doses: 0.0; 0.5; 2.5 and 5.0 mg/kg for 60 days in 18-month-old mice. After the treatment, locomotor activity in a novel environment and spatial memory in the water labyrinth were evaluated. Mice treated with bexarotene did not show significant changes in their behavior. Moreover, bexarotene-treated mice only showed a significant increase in the density of the dendritic spines and the dendritic length in the nucleus accumbens (NAcc) neurons. In conclusion, the administration of bexarotene improves the plasticity of the NAcc of aged mice, and therefore could be a pharmacological alternative to prevent or delay neuroplasticity disruptions in brain aging.

Glia Maturation Factor in the Pathogenesis of Alzheimer's disease

Alzheimer's disease (AD) is a neurodegenerative and neuroinflammatory disease characterized by the presence of extracellular amyloid plaques (APs) and intracellular neurofibrillary tangles (NFTs) in the brain. There is no disease modifying therapeutic options currently available for this disease. Hippocampus, entorhinal cortex (Broadmann area 28), perirhinal cortex (Broadmann area 35) and insular cortices are areas within the brain that are first ones to be severely affected in AD. Neuroinflammation is an important factor that induces neurodegeneration in AD. Glia maturation factor (GMF), a proinflammatory factor plays a crucial role in AD through activation of microglia and astrocytes to release proinflammatory mediators in the brain. Through immunohistochemical studies, we have previously shown that GMF is highly expressed in the vicinity of APs and NFTs in AD brains. Glial fibrillary acidic protein (GFAP), reactive astrocytes, ionized calcium binding adaptor molecule-1 (Iba-1) labelled activated microglia and GMF immunoreactive glial cells are increased in the entorhinal cortical layers especially at the sites of APs and Tau containing NFTs indicating a role for GMF. Overexpression of GMF in glial cells leads to neuroinflammation and neurodegeneration. Inhibition of GMF expression reduces neurodegeneration. Therefore, we suggest that GMF is a novel therapeutic target not only for AD but also for various other neurodegenerative diseases.

Next Generation Precision Medicine: CRISPR-mediated Genome Editing for the Treatment of Neurodegenerative Disorders

Despite significant advancements in the field of molecular neurobiology especially neuroinflammation and neurodegeneration, the highly complex molecular mechanisms underlying neurodegenerative diseases remain elusive. As a result, the development of the next generation neurotherapeutics has experienced a considerable lag phase. Recent advancements in the field of genome editing offer a new template for dissecting the precise molecular pathways underlying the complex neurodegenerative disorders. We believe that the innovative genome and transcriptome editing strategies offer an excellent opportunity to decipher novel therapeutic targets, develop novel neurodegenerative disease models, develop neuroimaging modalities, develop next-generation diagnostics as well as develop patient-specific precision-targeted personalized therapies to effectively treat neurodegenerative disorders including Alzheimer's disease, Parkinson's disease, Huntington's disease, Amyotrophic lateral sclerosis, Frontotemporal dementia etc. Here, we review the latest developments in the field of CRISPR-mediated genome editing and provide unbiased futuristic insights regarding its translational potential to improve the treatment outcomes and minimize financial burden. However, despite significant advancements, we would caution the scientific community that since the CRISPR field is still evolving, currently we do not know the full spectrum of CRISPR-mediated side effects. In the wake of the recent news regarding CRISPR-edited human babies being born in China, we urge the scientific community to maintain high scientific and ethical standards and utilize CRISPR for developing in vitro disease in a dish model, in vivo testing in nonhuman primates and lower vertebrates and for the development of neurotherapeutics for the currently incurable neurodegenerative disorders. Graphical Abstract.

Glia Maturation Factor and Mast Cell-Dependent Expression of Inflammatory Mediators and Proteinase Activated Receptor-2 in Neuroinflammation

Parkinson's disease (PD) is characterized by the presence of inflammation-mediated dopaminergic neurodegeneration in the substantia nigra. Inflammatory mediators from activated microglia, astrocytes, neurons, T-cells and mast cells mediate neuroinflammation and neurodegeneration. Administration of neurotoxin 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine (MPTP)-induces PD like motor deficits in rodents. 1-methyl-4-phenylpyridinium (MPP+), a toxic metabolite of MPTP activates glial cells, neurons and mast cells to release neuroinflammatory mediators. Glia maturation factor (GMF), mast cells and proteinase activated receptor-2 (PAR-2) are implicated in neuroinflammation. Alpha-synuclein which induces neurodegeneration increases PAR-2 expression in the brain. However, the exact mechanisms are not yet understood. In this study, we quantified inflammatory mediators in the brains of MPTP-administered wild type (Wt), GMF-knockout (GMF-KO), and mast cell knockout (MC-KO) mice. Additionally, we analyzed the effect of MPP+, GMF, and mast cell proteases on PAR-2 expression in astrocytes and neurons in vitro. Results show that the levels of interleukin-1beta (IL-1β), tumor necrosis factor-alpha (TNF-α), and the chemokine (C-C motif) ligand 2 (CCL2) were lesser in the brains of GMF-KO mice and MC-KO mice when compared to Wt mice brain after MPTP administration. Incubation of astrocytes and neurons with MPP+, GMF, and mouse mast cell protease-6 (MMCP-6) and MMCP-7 increased the expression of PAR-2. Our studies show that the absence of mast cells and GMF reduce the expression of neuroinflammatory mediators in the brain. We conclude that GMF along with mast cell interactions with glial cells and neurons during neuroinflammation can be explored as a new therapeutic target for PD and other neuroinflammatory disorders.

Synergy in Disruption of Mitochondrial Dynamics by Aβ (1-42) and Glia Maturation Factor (GMF) in SH-SY5Y Cells Is Mediated Through Alterations in Fission and Fusion Proteins

The pathological form of amyloid beta (Aβ) peptide is shown to be toxic to the mitochondria and implicates this organelle in the progression and pathogenesis of Alzheimer's disease (AD). Mitochondria are dynamic structures constantly undergoing fission and fusion, and altering their shape and size while traveling through neurons. Mitochondrial fission (Drp1, Fis1) and fusion (OPA1, Mfn1, and Mfn2) proteins are balanced in healthy neuronal cells. Glia maturation factor (GMF), a neuroinflammatory protein isolated and cloned in our laboratory plays an important role in the pathogenesis of AD. We hypothesized that GMF, a brain-localized inflammatory protein, promotes oxidative stress-mediated disruption of mitochondrial dynamics by alterations in mitochondrial fission and fusion proteins which eventually leads to apoptosis in the Aβ (1-42)-treated human neuroblastoma (SH-SY5Y) cells. The SH-SY5Y cells were incubated with GMF and Aβ (1-42) peptide, and mitochondrial fission and fusion proteins were analyzed by immunofluorescence, western blotting, and co-immunoprecipitation. We report that SH-SY5Y cells incubated with GMF and Aβ (1-42) promote mitochondrial fragmentation, by potentiating oxidative stress, mitophagy and shifts in the Bax/Bcl2 expression and release of cytochrome-c, and eventual apoptosis. In the present study, we show that GMF and Aβ treatments significantly upregulate fission proteins and downregulate fusion proteins. The study shows that extracellular GMF is an important inflammatory mediator that mediates mitochondrial dynamics by altering the balance in fission and fusion proteins and amplifies similar effects promoted by Aβ. Upregulated GMF in the presence of Aβ could be an additional risk factor for AD, and their synergistic actions need to be explored as a potential therapeutic target to suppress the progression of AD.

CRISPR/Cas9 Editing of Glia Maturation Factor Regulates Mitochondrial Dynamics by Attenuation of the NRF2/HO-1 Dependent Ferritin Activation in Glial Cells

Microglial cells are brain specific professional phagocytic immune cells that play a crucial role in the inflammation- mediated neurodegeneration especially in Parkinson's disease (PD) and Alzheimer's disease. Glia maturation factor (GMF) is a neuroinflammatory protein abundantly expressed in the brain. We have previously shown that GMF expression is significantly upregulated in the substantia nigra (SN) of PD brains. However, its possible role in PD progression is still not fully understood. The Clustered-Regularly Interspaced Short Palindromic Repeats (CRISPR)-CRISPR Associated (Cas) protein9 (CRISPR/Cas9) system is a simple, rapid and often extremely efficient gene editing tool at desired loci, enabling complete gene knockout or homology directed repair. In this study, we examined the effect of GMF editing by using the CRISPR/Cas9 technique in BV2 microglial cells (hereafter referred to as BV2-G) on oxidative stress and nuclear factor erythroid 2-related factor 2 (NRF2)/Hemeoxygenase1 (HO-1)-dependent ferritin activation after treatment with (1-methyl-4-phenylpyridinium) MPP⁺. Knockout of GMF in BV2-G cells significantly attenuated oxidative stress via reduced ROS production and calcium flux. Furthermore, deficiency of GMF significantly reduced nuclear translocation of NRF2, which modulates HO-1 and ferritin activation, cyclooxygenase 2 (COX2) and nitric oxide synthase 2 (NOS2) expression in BV2 microglial cells. Lack of GMF significantly improved CD11b and CD68 positive microglial cells as compared with untreated cells. Our results also suggest that pharmacological and genetic intervention targeting GMF may represent a promising and a novel therapeutic strategy in controlling Parkinsonism by regulating microglial functions. Targeted regulation of GMF possibly mediates protein aggregation in microglial homeostasis associated with PD progression through regulation of iron metabolism by modulating NRF2-HO1 and ferritin expression.

First description of enhanced expression of transforming growth factor-alpha (TGF-α) and glia maturation factor-beta (GMF-β) correlate with severity of neuropathology in border disease virus-infected small ruminants

Border disease (BD) is caused by Pestivirus and characterized by severe neuropathology, and histopathologically observed severe hypomyelination. We have previously shown that small ruminants infected with border disease virus (BDV) play an important role for neuropathology and pathogenesis of severe oxidative damage in brain tissue, neuronal mtDNA; in the production of high pathologic levels of nitric oxide; in glial cell activation and stimulation of intrinsic apoptosis pathway. This study aimed to investigate the relationship between glia maturation factor beta (GMF-β) and transforming growth factor alpha (TGF-α) expressions and the causes of BDV-induced neuropathology and to investigate their role in neuropathogenesis in a way that was not presented before. Expression levels of GMF-β and TGF-α were investigated. Results of the study revealed that the levels of GMF-β (P < 0.005) and TGF-α (P < 0.005) expression in the brain tissue markedly increased in the BDV-infected animals compared to the non-infected healthy control group. While TGF-α expressions were predominantly observed in neurons, GMF-β expressions were found in astrocytes, glial cells and neurons. These results were reasonable to suggest that BDV-mediated increased GMF-β might play a pivotal role neuropathogenesis and a different type of role in the mechanism of neurodegeneration/neuropathology in the process of BD. The results also indicated that increased levels of GMF up-regulation in glial cells and neurons causes neuronal destruction, suggesting pathological pathway involving GMF-mediated brain cell cytotoxicity. It is clearly indicated that the cause of astrogliosis is due to severe TGF-a expression. This is the first study to demonstrate the expression of GMF-β and TGF-α in neurons and reactive glial cells and its association with neuropathology in BD.

Targeted Gene Editing of Glia Maturation Factor in Microglia: a Novel Alzheimer's Disease Therapeutic Target

Alzheimer's disease (AD) is a devastating, progressive neurodegenerative disorder that leads to severe cognitive impairment in elderly patients. Chronic neuroinflammation plays an important role in the AD pathogenesis. Glia maturation factor (GMF), a proinflammatory molecule discovered in our laboratory, is significantly upregulated in various regions of AD brains. We have previously reported that GMF is predominantly expressed in the reactive glial cells surrounding the amyloid plaques (APs) in the mouse and human AD brain. Microglia are the major source of proinflammatory cytokines and chemokines including GMF. Recently clustered regularly interspaced short palindromic repeats (CRISPR) based genome editing has been recognized to study the functions of genes that are implicated in various diseases. Here, we investigated if CRISPR-Cas9-mediated GMF gene editing leads to inhibition of GMF expression and suppression of microglial activation. Confocal microscopy of murine BV2 microglial cell line transduced with an adeno-associated virus (AAV) coexpressing Staphylococcus aureus (Sa) Cas9 and a GMF-specific guide RNA (GMF-sgRNA) revealed few cells expressing SaCas9 while lacking GMF expression, thereby confirming successful GMF gene editing. To further improve GMF gene editing efficiency, we developed lentiviral vectors (LVs) expressing either Streptococcus pyogenes (Sp) Cas9 or GMF-sgRNAs. BV2 cells cotransduced with LVs expressing SpCas9 and GMF-sgRNAs revealed reduced GMF expression and the presence of indels in the exons 2 and 3 of the GMF coding sequence. Lipopolysaccharide (LPS) treatment of GMF-edited cells led to reduced microglial activation as shown by reduced p38 MAPK phosphorylation. We believe that targeted in vivo GMF gene editing has a significant potential for developing a unique and novel AD therapy.

Oxytocin and excitation/inhibition balance in social recognition

Social recognition is the sensitive domains of complex behavior critical for identification, interpretation and storage of socially meaningful information. Social recognition develops throughout childhood and adolescent, and is affected in a wide variety of psychiatric disorders. Recently, new data appeared on the molecular mechanisms of these processes, particularly, the excitatory-inhibitory (E/I) ratio which is modified during development, and then E/I balance is established in the adult brain. While E/I imbalance has been proposed as a mechanism for schizophrenia, it also seems to be the common mechanism in autism spectrum disorder (ASD). In addition, there is a strong suggestion that the oxytocinergic system is related to GABA-mediated E/I control in the context of brain socialization. In this review, we attempt to summarize the underpinning molecular mechanisms of E/I balance and its imbalance, and related biomarkers in the brain in healthiness and pathology. In addition, because there are increasing interest on oxytocin in the social neuroscience field, we will pay intensive attention to the role of oxytocin in maintaining E/I balance from the viewpoint of its effects on improving social impairment in psychiatric diseases, especially in ASD.

Mast Cell Proteases Activate Astrocytes and Glia-Neurons and Release Interleukin-33 by Activating p38 and ERK1/2 MAPKs and NF-κB

Inflammatory mediators released from activated microglia, astrocytes, neurons, and mast cells mediate neuroinflammation. Parkinson's disease (PD) is characterized by inflammation-dependent dopaminergic neurodegeneration in substantia nigra. 1-Methyl-4-phenylpyridinium (MPP⁺), a metabolite of parkinsonian neurotoxin 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine (MPTP), induces inflammatory mediators' release from brain cells and mast cells. Brain cells' interaction with mast cells is implicated in neuroinflammation. However, the exact mechanisms involved are not yet clearly understood. Mouse fetal brain-derived cultured primary astrocytes and glia-neurons were incubated with mouse mast cell protease-6 (MMCP-6) and MMCP-7, and mouse bone marrow-derived mast cells (BMMCs) were incubated with MPP⁺ and brain protein glia maturation factor (GMF). Interleukin-33 (IL-33) released from these cells was quantitated by enzyme-linked immunosorbent assay. Both MMCP-6 and MMCP-7 induced IL-33 release from astrocytes and glia-neurons. MPP⁺ and GMF were used as a positive control-induced IL-33 and reactive oxygen species expression in mast cells. Mast cell proteases and MPP⁺ activate p38 and extracellular signal-regulated kinases 1/2 (ERK1/2), mitogen-activated protein kinases (MAPKs), and transcription factor nuclear factor-kappa B (NF-κB) in astrocytes, glia-neurons, or mast cells. Addition of BMMCs from wt mice and transduction with adeno-GMF show higher chemokine (C-C motif) ligand 2 (CCL2) release. MPP⁺ activated glial cells and reduced microtubule-associated protein 2 (MAP-2) expression indicating neurodegeneration. IL-33 expression increased in the midbrain and striatum of PD brains as compared with age- and sex-matched control subjects. Glial cells and neurons interact with mast cells and accelerate neuroinflammation and these interactions can be explored as a new therapeutic target to treat PD.