Heat shock protein 70 suppresses neuroinflammation induced by α-synuclein in astrocytes

Aberrant CHCHD2-associated mitochondriopathy in Kii ALS/PDC astrocytes

Amyotrophic Lateral Sclerosis/Parkinsonism-Dementia Complex (ALS/PDC), a rare and complex neurological disorder, is predominantly observed in the Western Pacific islands, including regions of Japan, Guam, and Papua. This enigmatic condition continues to capture medical attention due to affected patients displaying symptoms that parallel those seen in either classical amyotrophic lateral sclerosis (ALS) or Parkinson's disease (PD). Distinctly, postmortem examinations of the brains of affected individuals have shown the presence of α-synuclein aggregates and TDP-43, which are hallmarks of PD and classical ALS, respectively. These observations are further complicated by the detection of phosphorylated tau, accentuating the multifaceted proteinopathic nature of ALS/PDC. The etiological foundations of this disease remain undetermined, and genetic investigations have yet to provide conclusive answers. However, emerging evidence has implicated the contribution of astrocytes, pivotal cells for maintaining brain health, to neurodegenerative onset, and likely to play a significant role in the pathogenesis of ALS/PDC. Leveraging advanced induced pluripotent stem cell technology, our team cultivated multiple astrocyte lines to further investigate the Japanese variant of ALS/PDC (Kii ALS/PDC). CHCHD2 emerged as a significantly dysregulated gene when disease astrocytes were compared to healthy controls. Our analyses also revealed imbalances in the activation of specific pathways: those associated with astrocytic cilium dysfunction, known to be involved in neurodegeneration, and those related to major neurological disorders, including classical ALS and PD. Further in-depth examinations revealed abnormalities in the mitochondrial morphology and metabolic processes of the affected astrocytes. A particularly striking observation was the reduced expression of CHCHD2 in the spinal cord, motor cortex, and oculomotor nuclei of patients with Kii ALS/PDC. In summary, our findings suggest a potential reduction in the support Kii ALS/PDC astrocytes provide to neurons, emphasizing the need to explore the role of CHCHD2 in maintaining mitochondrial health and its implications for the disease.

Fibrillar Alpha-Synuclein Alters the Intracellular Chaperone Levels within Hours of Its Internalization

Parkinson's disease (PD) is the second most prevalent neurodegenerative disorder worldwide. According to the Braak hypothesis, the disease spreads along specific neuroanatomical pathways. Studies indicate that fibrillar alpha-synuclein (F-αSyn) can propagate from cell-to-cell by following intercellular connections, leading to the selective death of certain cell groups like substantia nigra dopaminergic neurons and advancing the pathology. Internalized F-αSyn can be eliminated by lysosomes, proteasomes, or chaperones before it replicates inside the cell. Research has shown that F-αSyn can somehow escape from endosomes, lysosomes, and proteasomes and replicate itself. However, the impact of chaperones on intracellular levels during the initial hours of their internalization remains unknown. The present study investigates the effect of F-αSyn on chaperone levels within the first 6 and 12 h after internalization. Our findings showed that within the first 6 h, Hsc70 and Hsp90 levels were increased, while within 12 h, F-αSyn leads to a decrease or suppression of numerous intracellular chaperone levels. Exploring the pathological effects of PD on cells will contribute to identifying more targets for therapeutic interventions.

Heat shock response during the resolution of inflammation and its progressive suppression in chronic-degenerative inflammatory diseases

The heat shock response (HSR) is a crucial biochemical pathway that orchestrates the resolution of inflammation, primarily under proteotoxic stress conditions. This process hinges on the upregulation of heat shock proteins (HSPs) and other chaperones, notably the 70 kDa family of heat shock proteins, under the command of the heat shock transcription factor-1. However, in the context of chronic degenerative disorders characterized by persistent low-grade inflammation (such as insulin resistance, obesity, type 2 diabetes, nonalcoholic fatty liver disease, and cardiovascular diseases) a gradual suppression of the HSR does occur. This work delves into the mechanisms behind this phenomenon. It explores how the Western diet and sedentary lifestyle, culminating in the endoplasmic reticulum stress within adipose tissue cells, trigger a cascade of events. This cascade includes the unfolded protein response and activation of the NOD-like receptor pyrin domain-containing protein-3 inflammasome, leading to the emergence of the senescence-associated secretory phenotype and the propagation of inflammation throughout the body. Notably, the activation of the NOD-like receptor pyrin domain-containing protein-3 inflammasome not only fuels inflammation but also sabotages the HSR by degrading human antigen R, a crucial mRNA-binding protein responsible for maintaining heat shock transcription factor-1 mRNA expression and stability on heat shock gene promoters. This paper underscores the imperative need to comprehend how chronic inflammation stifles the HSR and the clinical significance of evaluating the HSR using cost-effective and accessible tools. Such understanding is pivotal in the development of innovative strategies aimed at the prevention and treatment of these chronic inflammatory ailments, which continue to take a heavy toll on global health and well-being.

Relationship among α‑synuclein, aging and inflammation in Parkinson's disease (Review)

Parkinson's disease (PD) is a common neurodegenerative pathology whose major clinical symptoms are movement disorders. The main pathological characteristics of PD are the selective death of dopaminergic (DA) neurons in the pars compacta of the substantia nigra and the presence of Lewy bodies containing α-synuclein (α-Syn) within these neurons. PD is associated with numerous risk factors, including environmental factors, genetic mutations and aging. In many cases, the complex interplay of numerous risk factors leads to the onset of PD. The mutated α-Syn gene, which expresses pathologicalα-Syn protein, can cause PD. Another important feature of PD is neuroinflammation, which is conducive to neuronal death. α-Syn is able to interact with certain cell types in the brain, including through phagocytosis and degradation of α-Syn by glial cells, activation of inflammatory pathways by α-Syn in glial cells, transmission of α-Syn between glial cells and neurons, and interactions between peripheral immune cells and α-Syn. In addition to the aforementioned risk factors, PD may also be associated with aging, as the prevalence of PD increases with advancing age. The aging process impairs the cellular clearance mechanism, which leads to chronic inflammation and the accumulation of intracellular α-Syn, which results in DA neuronal death. In the present review, the age-associated α-Syn pathogenicity and the interactions between α-Syn and certain types of cells within the brain are discussed to facilitate understanding of the mechanisms of PD pathogenesis, which may potentially provide insight for the future clinical treatment of PD.

Investigating the neuroprotective potential of rAAV2-PCBP1-EGFP gene therapy against a 6-OHDA-induced model of Parkinson's disease

OBJECTIVES

Previous studies have suggested a potential link between poly(rC)-binding protein 1 (PCBP1) and neurodegenerative diseases, including Parkinson's disease (PD). However, the precise role of PCBP1 in the pathogenesis of PD remains unclear. Therefore, the main objective of this study was to investigate the neuroprotective effects of PCBP1 in a PD model.

METHODS

To evaluate the neuroprotective potential of PCBP1, we conducted cell count assays and observed the expression of heat shock protein 70 (HSP70) in SH-SY5Y cells exposed to 6-OHDA-induced neurotoxicity. Additionally, we utilized recombinant adeno-associated virus (rAAV2) vectors encoding PCBP1 or EGFP, which were injected into the rat striatum. After 2 weeks of vector or saline injection, 6-OHDA was administered to the rat striatum. Behavioral assessments using the open field test (OFT) were performed weekly for 7 weeks. At the seventh week after 6-OHDA injection, immunohistochemistry and protein expression analyses were conducted in the three groups.

RESULTS

The results indicated that PCBP1 treatment significantly reduced the proliferation of 6-OHDA-induced SH-SY5Y cells. Additionally, in surviving cells, overexpression of PCBP1 enhanced the expression of HSP70. Similarly, rAAV2 vectors effectively delivered PCBP1 into the brain, resulting in sustained expression of rAAV2-PCBP1-EGFP. In the OFT, PCBP1 exhibited significant improvements in behavioral abnormalities and reduced anxiety in the PD model rats (p < .01). Moreover, PCBP1 effectively prevented the decrease of tyrosine hydroxylase and HSP70 expression in the lesioned side induced by 6-OHDA (p < .01). Consistent with expectations, PCBP1 efficiently protected against cell death caused by 6-OHDA (p < .01).

CONCLUSIONS

In conclusion, our findings provide compelling evidence for the beneficial effects of PCBP1 in the PD model, suggesting that PCBP1 could be a potential therapeutic target for PD.

LRRK2 G2019S and Parkinson's disease: insight from Neuroinflammation

The multiple hypothesis holds that the pathogenesis of Parkinson's disease (PD) requires many factors such as heredity, environment and ageing. Mutations in Leucine-rich repeat kinase 2 (LRRK2) are recognized the risk factors of PD, and closely related to sporadic and familial PD and can regulate a variety of cellular pathways and processes. An Increasing number of studies has shown that glial hyperactivation-mediated neuroinflammation participates in dopaminergic neuron degeneration and pathogenesis of PD. LRRK2 is essential to the regulaton of chronic inflammation, especially for the central nervous system. The review spotlights on the novel development of LRRK2 on microglia and astrocytes, and explore their potential therapeutic targets, in order to provide a new insights in PD. Key messages: What is already known on this topic The G2019S mutation of LRRK2 is now recognised as a pathogenic mutation in PD. Previous studies have focused on the relationship between neurons and LRRK2 G2019S. What this study adds Neuroinflammation mediated by LRRK2 G2019S of glial cells affects the progress and development of PD and attention must be paid to the role of LRRK2 G2019S in glial cells in PD. How this study might affect research, practice or policy Developing anti-inflammatory drugs from the perspective of LRRK2 G2019S of glial cells is a new direction for the treatment of PD.

Linking Heat Shock Protein 70 and Parkin in Parkinson's Disease

Parkinson's disease (PD) is a neurodegenerative disease that affects millions of elderly people worldwide and is characterized by the progressive loss of dopaminergic neurons in the substantia nigra pars compacta (SNpc). The precise mechanisms underlying the pathogenesis of PD are still not fully understood, but it is well accepted that the misfolding, aggregation, and abnormal degradation of proteins are the key causative factors of PD. Heat shock protein 70 (Hsp70) is a molecular chaperone that participates in the degradation of misfolded and aggregated proteins in living cells and organisms. Parkin, an E3 ubiquitin ligase, participates in the degradation of proteins via the proteasome pathway. Recent studies have indicated that both Hsp70 and Parkin play pivotal roles in PD pathogenesis. In this review, we focus on discussing how dysregulation of Hsp70 and Parkin leads to PD pathogenesis, the interaction between Hsp70 and Parkin in the context of PD and their therapeutic applications in PD.

Modulating Stress Proteins in Response to Therapeutic Interventions for Parkinson's Disease

Parkinson's disease (PD) is a neurodegenerative illness characterized by the degeneration of dopaminergic neurons in the substantia nigra, resulting in motor symptoms and without debilitating motors. A hallmark of this condition is the accumulation of misfolded proteins, a phenomenon that drives disease progression. In this regard, heat shock proteins (HSPs) play a central role in the cellular response to stress, shielding cells from damage induced by protein aggregates and oxidative stress. As a result, researchers have become increasingly interested in modulating these proteins through pharmacological and non-pharmacological therapeutic interventions. This review aims to provide an overview of the preclinical experiments performed over the last decade in this research field. Specifically, it focuses on preclinical studies that center on the modulation of stress proteins for the treatment potential of PD. The findings display promise in targeting HSPs to ameliorate PD outcomes. Despite the complexity of HSPs and their co-chaperones, proteins such as HSP70, HSP27, HSP90, and glucose-regulated protein-78 (GRP78) may be efficacious in slowing or preventing disease progression. Nevertheless, clinical validation is essential to confirm the safety and effectiveness of these preclinical approaches.

Early clues and molecular mechanism involved in neurodegenerative diseases induced in immature mice by combined exposure to polypropylene microplastics and DEHP

Studies have shown that exposure to either microplastics (MPs) or di-(2-ethylhexyl) phthalic acid (DEHP) alone can cause neurotoxicity in animals, but it remains uncertain whether and to what extent co-exposure to these two substances, which often occur together in reality, can also induce neurotoxicity. This study aimed to investigate the neurotoxicity and molecular mechanisms of combined exposure to DEHP and polypropylene microplastics (synthetic PP-MPs were used), the microplastics most commonly encountered by young children, in immature mice. The results showed that exposure to PP-MPs and/or DEHP did cause neurotoxic effects in immature mice, including induction of neurocognitive and memory deficits, damage to the CA3 region of the hippocampus, increased oxidative stress, and decreased AChE activity in the brain. The severity of the neurotoxicity increased with increasing concentrations of PP-MPs, combined exposure to PP-MPs and DEHP exhibited additive or synergistic effects. Transcriptomic analyses revealed that the PP-MPs and/or DEHP exposure altered the expression profiles of gene clusters involved in the stress response, and in protein processing in endoplasmic reticulum. Quantitative analyses further indicated that PP-MPs and/or DEHP exposure inhibited the activity of the heat shock response mediated by heat shock transcription factor 1, while chronically activated the unfolded protein response, consequently inducing neurotoxicity through neuronal apoptosis and neuroinflammation in the immature mice. As a pioneer study to highlight the neurotoxicity induced by combined exposure to PP-MPs and DEHP in immature mice, this research provides new insights into mitigating the health risks of PP-MPs and DEHP exposure in young children.

Potential application of heat shock proteins as therapeutic targets in Parkinson's disease

Parkinson's disease (PD) is a common chronic neurodegenerative disease, and the heat shock proteins (HSPs) are proved to be of great value for PD. In addition, HSPs can maintain protein homeostasis, degrade and inhibit protein aggregation by properly folding and activating intracellular proteins in PD. This study mainly summarizes the important roles of HSPs in PD and explores their feasibility as targets. We introduced the structural and functional characteristics of HSPs and the physiological functions of HSPs in PD. HSPs can protect neurons from damage by degrading aggregates with three mechanisms, including the aggregation and removing α-Synuclein (α-Syn) aggregates, promotion the autophagy of abnormal proteins, and inhibition the apoptosis of degenerated neurons. This study underscores the importance of HSPs as targets in PD and helps to expand new mechanisms in PD treatment strategies.

Caveolin-1 Promotes the Imbalance of Th17/Treg in Chronic Obstructive Pulmonary Disease by Regulating Hsp70 Expression

Objective

To investigate whether the expression of Hsp70 is associated with Cav-1 in promoting the imbalance of Th17/Treg cells in COPD.

Methods

The plasma Cav-1, Hsp70 expression were quantified by enzyme-linked immunosorbent assay (ELISA). The frequencies of circulating Th17, Treg cells and Th17/Treg ratio were determined by flow cytometry. Peripheral blood mononuclear cells (PBMCs) from subjects were transfected with Cav-1 or control plasmids and Hsp70 plasmid.

Results

We found that Cav-1 expression was lower but the levels of Hsp70 and Th17 cells were higher in COPD than in healthy control (HC). Hsp70 expressions were positively correlated with Cav-1 levels, Th17 cells, and Th17/Treg ratio in COPD but not in HC. Cav-1 over-expression resulted in an increase in Hsp70 and Th17 levels. Suppressing Hsp70 expressing by small interfering RNA (siRNA), the decline of Th17 frequency was observed in Cav-1-overexpressed PBMCs.

Conclusion

Collectively, our results illuminate that Cav-1 contributes to the imbalance of Th17/Treg through potentially regulating Hsp70 expression.

Exogenous recombinant Hsp70 attenuates sevoflurane anesthesia-induced cognitive dysfunction in aged mice

BACKGROUND

Postoperative cognitive dysfunction (POCD) is a severe postoperative neurological sequela in elderly patients, and there is currently no standard treatment for POCD. In this study, whether recombinant human heat shock protein 70 (rHsp70) could alleviate sevoflurane-induced cognitive impairment in aged mice is investigated.

METHODS

To determine the prophylactic effect of rHsp70 in sevoflurane-induced cognitive dysfunction, aged mice were pretreated with different concentrations of rHsp70 (29.4, 58.8, and 117.6 μg/kg; intranasal injected; N = 12) every day for 1 week; then, 3% sevoflurane was utilized to anesthetize the aged mice. Cognitive function, neurotoxicity, and serum and hippocampal Hsp70 levels in aged mice undergoing sevoflurane anesthesia were assessed by the Morris water maze test and enzyme-linked immunosorbent assay. The effects of rHsp70 on inflammatory response were assessed by proinflammatory cytokine production and nuclear factor-κB (NF-κB) activation assays.

RESULTS

We found that aged mice exposed to sevoflurane showed reduced learning and memory ability and reduced Hsp70 expression, which were both restored by rHsp70 pretreatment. RHsp70 also reversed sevoflurane-induced up-regulated Bax and Bcl-2 expression and interleukin-1, IL-6, and monocyte chemoattractant protein-1 overproduction. Finally, rHsp70 pretreatment suppressed sevoflurane-induced NF-κB activation. Our study indicated that rHsp70 was sufficient to suppress sevoflurane-induced cognitive decline and neurotoxicity.

CONCLUSION

Our important finding warrants further study on the clinical application of rHsp70 in elderly patients undergoing anesthesia.

Natural medicine HLXL targets multiple pathways of amyloid-mediated neuroinflammation and immune response in treating alzheimer's disease

BACKGROUND

Based on the complex pathology of AD, a single chemical approach may not be sufficient to deal simultaneously with multiple pathways of amyloid-tau neuroinflammation. A polydrug approach which contains multiple bioactive components targeting multiple pathways in AD would be more appropriate. Here we focused on a Chinese medicine (HLXL), which contains 56 bioactive natural products identified in 11 medicinal plants and displays potent anti-inflammatory and immuno-modulatory activity.

HYPOTHESIS/PURPOSE

We investigated the neuroimmune and neuroinflammation mechanisms by which HLXL may attenuate AD neuropathology. Specifically, we investigated the effects of HLXL on the neuropathology of AD using both transgenic mouse models as well as microglial cell-based models.

STUDY DESIGN

The 5XFAD transgenic animals and microglial cell models were respectively treated with HLXL and Aβ42, and/or lipopolysaccharide (LPS), and then analyzed focusing on microglia mediated Aβ uptake and clearance, as well as pathway changes.

METHODS

We showed that HLXL significantly reduced amyloid neuropathology by upregulation of microglia-mediated phagocytosis of Aβ both in vivo and in vitro. HLXL displayed multi-modal mechanisms regulating pathways of phagocytosis and energy metabolism.

RESULTS

Our results may not only open a new avenue to support pharmacologic modulation of neuroinflammation and the neuroimmune system for AD intervention, but also identify HLXL as a promising natural medicine for AD.

CONCLUSION

It is conceivable that the traditional wisdom of natural medicine in combination with modern science and technology would be the best strategy in developing effective therapeutics for AD.

Biological aging of CNS-resident cells alters the clinical course and immunopathology of autoimmune demyelinating disease

Biological aging is the strongest factor associated with the clinical phenotype of multiple sclerosis (MS). Relapsing-remitting MS typically presents in the third or fourth decade, whereas the mean age of presentation of progressive MS (PMS) is 45 years old. Here, we show that experimental autoimmune encephalomyelitis (EAE), induced by the adoptive transfer of encephalitogenic CD4⁺ Th17 cells, was more severe, and less likely to remit, in middle-aged compared with young adult mice. Donor T cells and neutrophils were more abundant, while B cells were relatively sparse, in CNS infiltrates of the older mice. Experiments with reciprocal bone marrow chimeras demonstrated that radio-resistant, nonhematopoietic cells played a dominant role in shaping age-dependent features of the neuroinflammatory response, as well as the clinical course, during EAE. Reminiscent of PMS, EAE in middle-aged adoptive transfer recipients was characterized by widespread microglial activation. Microglia from older mice expressed a distinctive transcriptomic profile suggestive of enhanced chemokine synthesis and antigen presentation. Collectively, our findings suggest that drugs that suppress microglial activation, and acquisition or expression of aging-associated properties, may be beneficial in the treatment of progressive forms of inflammatory demyelinating disease.

Predictive Value of Heat-Shock Protein Gene Expression on Severe Neonatal Hypoxic-Ischemic Encephalopathy

This study aims to evaluate significant gene expression in severe hypoxic ischemic encephalopathy (HIE) in newborns, which can be used as a predictable measure for high-risk HIE infants. The study prospectively recruited 77 inborn near-term or term HIE newborns between January 2018 and December 2020. We measured six different genes within 6 h of life among the HIE infants and compared the gene levels between the mild- and severe-HIE groups. Among these, 64 HIE infants (83.1%) did not receive therapeutic hypothermia (TH) because they were categorized as mild HIE, and the 13 remaining (16.9%) infants were categorized as ≥ moderate-HIE group and received TH. More abnormal MRI findings, seizure, and use of anti-convulsant were more found in the ≥ moderate = HIE group along with longer mechanical ventilation days and hospitalization. Heat-shock protein 70 family 1 A (HSPA1A) and serpin family H member 1 (SERPINH1) genes, which encode heat-shock protein (HSP) 70 and 47, respectively, were significantly elevated in the ≥ moderate-HIE, seizure, and abnormal MRI groups. HSP 70 and 47 were significantly elevated in the severe-HIE group, possibly playing protective roles in inhibiting exacerbated neuroinflammation and maintaining a cellular homeostasis. At 18–24 months, ≥ moderate-HIE group manifested a significant language delay.

Glial changes in schizophrenia: Genetic and epigenetic approach

BACKGROUND

Schizophrenia (SCZ) is a severe mental illness that affects one percent of the population, affecting how people think, feel, and behave. Evidence suggests glial cell alteration and some researchers have found genetic risk loci and epigenetic marks that may regulate glia-related genes implicated in SCZ.

AIM

The aim of this study is to identify genetic and epigenetic changes that have been reported in glial cells or glial-associated genes in SCZ.

MATERIALS AND METHODS

We searched the articles from PubMed, PubMed Central, Medline, Medscape, and Embase databases up to December 2020 to identify relevant peer-reviewed articles in English. The titles and abstracts were screened to eliminate irrelevant citations.

RESULTS

Twenty-four original articles were included in the review. Studies were categorized into the following four thematic via: (1) oligodendrocytes, (2) microglia, (3) astrocytes, and (4) perspectives.

CONCLUSION

This study is the first of its kind to review research on genetic variants and epigenetic modifications associated with glia-related genes implicated in SCZ. Epigenetic evidence is considerably less than genetic evidence in this field. Understanding the pathways of some risk genes and their genetic and epigenetic regulation allows us to understand and find potential targets for future interventions in this mental illness.

Impact of Low Humidity on Damage-associated Molecular Patterns at the Ocular Surface during Dry Eye Disease

SIGNIFICANCE

Dry eye is one of the leading causes for individuals to seek eye care, whereas the pathogenesis is poorly understood. One mechanism in which dry eye inflammation may ensue is by the release of damage-associated molecular patterns (DAMPs) by damaged cells to stimulate the production of cytokines and matrix metalloproteinases. Examining DAMP levels on the ocular surface during dry eye disease (DED) will increase our understanding of their potential involvement in the pathogenesis of DED.

PURPOSE

This study aimed to quantitate DAMPs, high-mobility group box 1 (HMGB1), and heat shock proteins on the ocular surface of normal and dry eye subjects and to examine the impact of low-humidity environment (LHE) on DAMPs and inflammation in dry eye subjects.

METHODS

Basal tears (10 to 20 μL) and conjunctival impression cytology samples were analyzed for HMGB1, HSP-27, HSP-60, HSP-70, and HSP-90α by ELISA or Luminex assays in normal (n = 15) and DED (n = 15) subjects. In addition, a subset of DED subjects were exposed to LHE for 2 hours. The level of DAMPs in the tear film was evaluated by ELISA or Luminex assay. Interleukin 6, interleukin 8, or metalloproteinase (MMP) 9 mRNA were quantitated by real-time polymerase chain reaction from conjunctival impression cytology samples.

RESULTS

Compared with age-matched normal subjects, HMGB1 was significantly elevated in the tear film of DED subjects (P = .03), whereas there was no significant difference in heat shock proteins. Conjunctival impression cytology samples revealed no significant difference in intracellular DAMP levels between both groups. After exposure to an LHE, there was an increase in corneal staining (P = .005), HSP-60 levels in the tear film (P = .01), and MMP-9 mRNA in the conjunctiva (P = .001).

CONCLUSIONS

Dry eye subjects had higher levels of HMGB1 in their tear film. Exposure to an LHE worsened corneal staining, increased conjunctival MMP-9 mRNA expression, and increased tear film HSP-60 levels. Larger studies are needed to understand the involvement of DAMPs in stimulating dry eye inflammation.

Astrocytes, a Promising Opportunity to Control the Progress of Parkinson's Disease

At present, there is no efficient treatment to prevent the evolution of Parkinson’s disease (PD). PD is generated by the concurrent activity of multiple factors, which is a serious obstacle for the development of etio-pathogenic treatments. Astrocytes may act on most factors involved in PD and the promotion of their neuroprotection activity may be particularly suitable to prevent the onset and progression of this basal ganglia (BG) disorder. The main causes proposed for PD, the ability of astrocytes to control these causes, and the procedures that can be used to promote the neuroprotective action of astrocytes will be commented upon, here.

Dexamethasone-induced activation of heat shock response ameliorates seizure susceptibility and neuroinflammation in mouse models of Lafora disease

Heat shock response (HSR) is a conserved cytoprotective pathway controlled by the master transcriptional regulator, the heat shock factor 1 (HSF1), that activates the expression of heat shock proteins (HSPs). HSPs, as chaperones, play essential roles in minimizing stress-induced damages and restoring proteostasis. Therefore, compromised HSR is thought to contribute to neurodegenerative disorders. Lafora disease (LD) is a fatal form of neurodegenerative disorder characterized by the accumulation of abnormal glycogen as Lafora bodies in neurons and other tissues. The symptoms of LD include progressive myoclonus epilepsy, dementia, and cognitive deficits. LD is caused by the defects in the gene coding laforin phosphatase or the malin ubiquitin ligase. Laforin and malin are known to work upstream of HSF1 and are essential for the activation of HSR. Herein, we show that mice deficient for laforin or malin show reduced levels of HSF1 and their targets in their brain tissues, suggesting compromised HSR; this could contribute to the neuropathology in LD. Intriguingly, treatment of LD animals with dexamethasone, a synthetic glucocorticoid analogue, partially restored the levels of HSF1 and its targets. Dexamethasone treatment was also able to ameliorate the neuroinflammation and susceptibility to induced seizures in the LD animals. However, dexamethasone treatment did not show a significant effect on Lafora bodies or autophagy defects. Taken together, the present study establishes a role for HSR in seizure susceptibility and neuroinflammation and dexamethasone as a potential antiepileptic agent, suitable for further studies in LD.

Activation of HSP70 impedes tert-butyl hydroperoxide (t-BHP)-induced apoptosis and senescence of human nucleus pulposus stem cells via inhibiting the JNK/c-Jun pathway

The endogenous repair failure of degenerated intervertebral disk (IVD) is highly related to the exhaustion of nucleus pulposus stem cells (NPSCs). Excessive oxidative stress could induce apoptosis and senescence of NPSCs, thus, declining the quantity and quality of NPSCs. Heat shock protein 70 (HSP70) is a family of cytoprotective and antioxidative proteins. However, there is no report on the protective effects of HSP70 on oxidative stress-induced NPSC impairments and underlying mechanisms. In the present study, we treated NPSCs with tert-butyl hydroperoxide (t-BHP) in vitro to simulate an oxidative stress condition. HSP70 inducer TRC051384 was used to evaluate the cytoprotective effects of HSP70. The results suggested that HSP70 impeded t-BHP-mediated cell viability loss and protected the ultrastructure of NPSCs. Moreover, t-BHP could induce mitochondrial apoptosis and p53/p21-mediated senescence of NPSCs, both of which were significantly inhibited in HSP70 activation groups. Excessive oxidative stress and mitochondrial dysfunction reinforced each other and contributed to the cellular damage processes. HSP70 decreased reactive oxygen species (ROS) production, rescued mitochondrial membrane potential (MMP) collapse, and blocked ATP depletion. Finally, our data showed that HSP70 downregulated the JNK/c-Jun pathway. Taken together, activation of HSP70 could protect against t-BHP-induced NPSC apoptosis and senescence, thus, improving the quantity and quality of NPSCs. Therefore, HSP70 may be a promising therapeutic target for IVD degeneration.

Phloretin and phloridzin guard against cisplatin-induced nephrotoxicity in mice through inhibiting oxidative stress and inflammation

AIM

Cisplatin (Cis) is widely used chemotherapeutic and has some serious side effects as nephrotoxicity. Phloretin (PH) and Phloridzin (PZ) are known their anti-oxidant anti-inflammatory effects. We aimed to examine the protective effects of PH and PZ on cisplatin-induced nephrotoxicity.

MAIN METHODS

Totally, 48 Balb/C female mice were separated into eight groups (n = 6). First day, single dose of cisplatin (20 mg/kg intraperitoneal) was administered to induce toxicity. PH and PZ were given (50 and 100 mg/kg orally) to treatment groups during 3 days. After the experimental procedures serum renal function enzymes (BUN and Creatinine), oxidative parameters (SOD, GSH and MDA), nuclear agent NFKβ, inflammatory cytokines (Tnf-α and IL1β) and HSP70 expressions and histopathological assessments were analyzed.

KEY FINDINGS

Serum enzymes, tissue cytokines and oxidative stress were increased after the Cis treatment. PH and PZ treatments normalized all parameters compared to Cis administrated group. After the treatments, SOD activities and GSH levels were increased while MDA levels were decreased. PH and PZ treatments decreased Tnf-α, IL1β and NFKβ mRNA expressions. Cis significantly increased the HSP70 expression while PH and PZ administrations significantly decreased. Similar the biochemical and molecular results, PH and PZ showed positive effects on tissue pathological parameters. Cisplatin cause a lot of abnormal structures as tubular and glomeruli damages on the kidney.

SIGNIFICANCE

PH and PZ play important physiological roles in the prevention of nephrotoxicity. Antioxidant and anti-inflammatory effects of PH and PZ demonstrated visible protective effects in the cisplatin-induced nephrotoxicity model.

The Role of Glial Mitochondria in α-Synuclein Toxicity

The abnormal accumulation of alpha-synuclein (α-syn) aggregates in neurons and glial cells is widely known to be associated with many neurodegenerative diseases, including Parkinson's disease (PD), Dementia with Lewy bodies (DLB), and Multiple system atrophy (MSA). Mitochondrial dysfunction in neurons and glia is known as a key feature of α-syn toxicity. Studies aimed at understanding α-syn-induced toxicity and its role in neurodegenerative diseases have primarily focused on neurons. However, a growing body of evidence demonstrates that glial cells such as microglia and astrocytes have been implicated in the initial pathogenesis and the progression of α-Synucleinopathy. Glial cells are important for supporting neuronal survival, synaptic functions, and local immunity. Furthermore, recent studies highlight the role of mitochondrial metabolism in the normal function of glial cells. In this work, we review the complex relationship between glial mitochondria and α-syn-mediated neurodegeneration, which may provide novel insights into the roles of glial cells in α-syn-associated neurodegenerative diseases.

Alarmins and c-Jun N-Terminal Kinase (JNK) Signaling in Neuroinflammation

Neuroinflammation is involved in the progression or secondary injury of multiple brain conditions, including stroke and neurodegenerative diseases. Alarmins, also known as damage-associated molecular patterns, are released in the presence of neuroinflammation and in the acute phase of ischemia. Defensins, cathelicidin, high-mobility group box protein 1, S100 proteins, heat shock proteins, nucleic acids, histones, nucleosomes, and monosodium urate microcrystals are thought to be alarmins. They are released from damaged or dying cells and activate the innate immune system by interacting with pattern recognition receptors. Being principal sterile inflammation triggering agents, alarmins are considered biomarkers and therapeutic targets. They are recognized by host cells and prime the innate immune system toward cell death and distress. In stroke, alarmins act as mediators initiating the inflammatory response after the release from the cellular components of the infarct core and penumbra. Increased c-Jun N-terminal kinase (JNK) phosphorylation may be involved in the mechanism of stress-induced release of alarmins. Putative crosstalk between the alarmin-associated pathways and JNK signaling seems to be inherently interwoven. This review outlines the role of alarmins/JNK-signaling in cerebral neurovascular inflammation and summarizes the complex response of cells to alarmins. Emerging anti-JNK and anti-alarmin drug treatment strategies are discussed.

Unravelling the Role of HSP70 as the Unexplored Molecular Target in Age-Related Macular Degeneration

The motive behind writing this paper was to highlight the relationship between heat shock protein 70 (HSP70) and age-related macular degeneration (AMD) to explore the potential role of HSP70 as a molecular target in AMD therapy. We performed a comprehensive literature search in various databases and finally found 43 relevant studies related to our objective. In our research, we found that in AMD, oxidative stress causes increased inflammation and excessive apoptosis due to the accumulation of aberrant proteins in retinal pigment epithelium (RPE) cells. The long-lasting overstimulation of the defence system leads to RPE degeneration and results in visual impairment or vision loss. However, after thorough research, it was found that HSP70's role as an immunomodulator, the guardian of the proteolytic pathway and regulator of apoptosis makes it a potential therapeutic target in AMD.

Astrocytes autophagy in aging and neurodegenerative disorders

Astrocytes can serve multiple functions in maintaining cellular homeostasis of the central nervous system (CNS), and normal functions for autophagy in astrocytes is considered to have very vital roles in the pathogenesis of aging and neurodegenerative diseases. Autophagy is a major intracellular lysosomal (or its yeast analog, vacuolar) clearance pathways involved in the degradation and recycling of long-lived proteins, oxidatively damaged proteins and dysfunctional organelles by lysosomes. Current evidence has shown that autophagy might influence inflammation, oxidative stress, aging and function of astrocytes. Although the interrelation between autophagy and inflammation, oxidative stress, aging or neurological disorders have been addressed in detail, the influence of astrocytes mediated-autophagy in aging and neurodegenerative disorders has yet to be fully reviewed. In this review, we will summarize the most up-to-date findings and highlight the role of autophagy in astrocytes and link autophagy of astrocytes to aging and neurodegenerative diseases. Due to the prominent roles of astrocytic autophagy in age-related neurodegenerative diseases, we believe that we can provide new suggestions for the treatment of these disorders.

Neurochemical regulation of the expression and function of glial fibrillary acidic protein in astrocytes

Glial fibrillary acidic protein (GFAP), a type III intermediate filament, is a marker of mature astrocytes. The expression of GFAP gene is regulated by many transcription factors (TFs), mainly Janus kinase-2/signal transducer and activator of transcription 3 cascade and nuclear factor κ-light-chain-enhancer of activated B cell signaling. GFAP expression is also modulated by protein kinase and other signaling molecules that are elicited by neuronal activity and hormones. Abnormal expression of GFAP proteins occurs in neuroinflammation, neurodegeneration, brain edema-eliciting diseases, traumatic brain injury, psychiatric disorders and others. GFAP, mainly in α-isoform, is the major component of cytoskeleton and the scaffold of astrocytes, which is essential for the maintenance of astrocytic structure and shape. GFAP also has highly morphological plasticity because of its quick changes in assembling and polymerizing states in response to environmental challenges. This plasticity and its corresponding cellular morphological changes endow astrocytes the functions of physical barrier between adjacent neurons and stabilizer of extracellular environment. Moreover, GFAP colocalizes and even molecularly associates with many functional molecules. This feature allows GFAP to function as a platform for direct interactions between different molecules. Last, GFAP involves transportation and localization of other functional proteins and thus serves as a protein transport guide in astrocytes. This guiding role of GFAP involves an elastic retraction and extension cytoskeletal network that couples with GFAP reassembling, transporting, and membrane protein recycling machinery. This paper reviews our current understanding of the expression and functions of GFAP as well as their regulation.

4-HNE induces proinflammatory cytokines of human retinal pigment epithelial cells by promoting extracellular efflux of HSP70

Oxidative stress and subsequent chronic inflammation result in dysfunction of the retinal pigment epithelium (RPE) and represent therapeutic targets in the context of age-related macular degeneration (AMD). However, molecular mechanisms that linked oxidative stress and inflammation still unclear. As an important byproduct of oxidative stress, 4-hydroxynonenal (4-HNE) induces apoptosis and lysosome dysregulation of RPE cells. In the present study, we evaluated cytokines production of RPE cells induced by 4-HNE by using cytokine array and confirmed that 4-HNE induced IL-6, IL-1β and TNF-α production in a concentration dependent manner. Specifically, 4-HNE also induced IL-10 and TGF-β production in low concentration. Molecular analysis revealed that intracellular HSP70 inhibited 4-HNE-induced production of pro-inflammatory cytokines, and 4-HNE exerted proinflammatory effects in RPE cells by enhancing extracellular release of HSP70, as efflux inhibitor Methyl-β-cyclodextrin (MBC) treatment significantly blocked the release of HSP70 and decreased IL-6 production of RPE cells induced by 4-HNE. Meanwhile, HSP70 inducer arimoclomol increased intracellular HSP70 production, but showed no influence on its extracellular level, also performed anti-inflammatory effects in 4-HNE-stimulated RPE cells. Whereas the anti-inflammatory effects of paeoniflorin, an HSP70 inducer simultaneously promoted its extracellular efflux, was lower than arimoclomol. In addition, we further confirmed that MBC exhibited synergetic effect with both paeoniflorin and arimoclomol to inhibit the production of proinflammatory cytokines induced by 4-HNE. Taken together, these results indicate that HSP70 plays a vital role in regulating inflammation of RPE cells induced by oxidative stress and might be a potential novel target for clinical treatment of AMD.

Physical Exercise Inhibits Inflammation and Microglial Activation

Accumulating evidence indicates that exercise can enhance brain function and attenuate neurodegeneration. Besides improving neuroplasticity by altering the synaptic structure and function in various brain regions, exercise also modulates multiple systems that are known to regulate neuroinflammation and glial activation. Activated microglia and several pro-inflammatory cytokines play active roles in the pathogenesis of neurodegenerative diseases, such as Alzheimer’s disease and Parkinson’s disease. The purpose of this review is to highlight the impacts of exercise on microglial activation. Possible mechanisms involved in exercise-modulated microglial activation are also discussed. Undoubtedly, more studies are needed in order to disclose the detailed mechanisms, but this approach offers therapeutic potential for improving the brain health of millions of aging people where pharmacological intervention has failed.

Connexin 43 hemichannels and pannexin-1 channels contribute to the α-synuclein-induced dysfunction and death of astrocytes

Diverse studies have suggested that cytoplasmic inclusions of misfolded α-synuclein in neuronal and glial cells are main pathological features of different α-synucleinopathies, including Parkinson's disease and dementia with Lewy bodies. Up to now, most studies have focused on the effects of α-synuclein on neurons, whereas the possible alterations of astrocyte functions and neuron-glia crosstalk have received minor attention. Recent evidence indicates that cellular signaling mediated by hemichannels and pannexons is critical for astroglial function and dysfunction. These channels constitute a diffusional route of communication between the cytosol and the extracellular space and during pathological scenarios they may lead to homeostatic disturbances linked to the pathogenesis and progression of different diseases. Here, we found that α-synuclein enhances the opening of connexin 43 (Cx43) hemichannels and pannexin-1 (Panx1) channels in mouse cortical astrocytes. This response was linked to the activation of cytokines, the p38 MAP kinase, the inducible nitric oxide synthase, cyclooxygenase 2, intracellular free Ca²⁺ concentration ([Ca²⁺ ]_i ), and purinergic and glutamatergic signaling. Relevantly, the α-synuclein-induced opening of hemichannels and pannexons resulted in alterations in [Ca²⁺ ]_i dynamics, nitric oxide (NO) production, gliotransmitter release, mitochondrial morphology, and astrocyte survival. We propose that α-synuclein-mediated opening of astroglial Cx43 hemichannels and Panx1 channels might constitute a novel mechanism involved in the pathogenesis and progression of α-synucleinopathies.

Hapln2 in Neurological Diseases and Its Potential as Therapeutic Target

Hyaluronan and proteoglycan link protein 2 (Hapln2) is important for the binding of chondroitin sulfate proteoglycans to hyaluronan. Hapln2 deficiency leads to the abnormal expression of extracellular matrix (ECM) proteins and dysfunctional neuronal conductivity, demonstrating the vital role of Hapln2 in these processes. Studies have revealed that Hapln2 promotes the aggregation of α-synuclein, thereby contributing to neurodegeneration in Parkinson’s disease (PD), and it was recently suggested to be in intracellular neurofibrillary tangles (NFTs). Additionally, the expression levels of Hapln2 showed lower in the anterior temporal lobes of individuals with schizophrenia than those of healthy subjects. Together, these studies implicate the involvement of Hapln2 in the pathological processes of neurological diseases. A better understanding of the function of Hapln2 in the central nervous system (CNS) will provide new insights into the molecular mechanisms of these diseases and help to establish promising therapeutic strategies. Herein, we review the recent progress in defining the role of Hapln2 in brain physiology and pathology.

Therapeutic effect of oligomeric proanthocyanidin in cuprizone-induced demyelination

NEW FINDINGS

What is the central question of this study? Oligomeric proanthocyanidin has the capacity to alleviate abnormalities in neurological functioning. However, whether oligomeric proanthocyanidin can reduce the progression of demyelination or promote remyelination in demyelinating diseases remains unknown. What is the main finding and its importance? Oligomeric proanthocyanidin can improve cuprizone-induced demyelination by inhibiting immune cell infiltration, reversing overactivated microglia, decreasing the inflammatory cytokines secreted by inflammatory cells and decreasing the production of myelin oligodendrocyte glycoprotein_35-55 -specific antibody in the brain.

ABSTRACT

Demyelinating diseases of the CNS, including multiple sclerosis, neuromyelitis optica and acute disseminated encephalomylitis, are characterized by recurrent primary demyelination-remyelination and progressive neurodegeneration. In the present study, we investigated the therapeutic effect of oligomeric proanthocyanidin (OPC), the most effective component of grape seed extract, in cuprizone-fed C57BL/6 mice, a classic demyelination-remyelination model. Our results showed that OPC attenuated abnormal behaviour, reduced demyelination and increased expression of myelin basic protein and expression of O4⁺ oligodendrocytes in the corpus callosum. Oligomeric proanthocyanidin also reduced the numbers of B and T cells, activated microglia in the corpus callosum and inhibited secretion of inflammatory factors. Furthermore, concentrations of myelin oligodendrocyte glycoprotein-specific antibodies were significantly reduced in serum and brain homogenates after OPC treatment. Together, these results demonstrate a potent therapeutic effect for OPC in cuprizone-mediated demyelination and clearly highlight multiple effects of this natural product in attenuating myelin-specific autoantibodies and the inflammatory microenvironment in the brain.

Differential Exosomic Proteomic Patterns and Their Influence in Resveratrol Sensitivities of Glioblastoma Cells

Glioblastoma multiforme (GBM) is the commonest primary brain malignancy with extremely poor prognosis. Resveratrol posseses anti-cancer effects, while GBM cells respond differently to it due to certain unknown reason(s). Because the tumor-derived exosomes are supposed to influence chemosensitivity, the exosomic proteins released from resveratrol-sensitive U251 and resveratrol-resistant glioblastoma LN428 cells are profiled before (N/Exo) and after drug treatment (Res/Exo) by label-free liquid chromatography-mass spectrometry (LC-MS). The therapeutic implications of the proteomic findings are estimated by gene ontology enrichment analysis (GO) and the Kyoto Encyclopedia of Genes and Genomes (KEGG)-based bioinformatic analyses and further elucidated by exosome co-incubating. The results reveal that U251/N/Exo but not U251/Res/Exo enhances resveratrol sensitivity of resveratrol-resistant LN428 cells. The resveratrol sensitive properties of U251 cells are not altered by either LN428/N/Exo or LN428/Res/Exo. U251/N/Exo contains higher levels of chromatin silencing and epidermis development proteins, while U251/Res/Exo has more oxygen transport and G protein-coupled receptor. Both of LN428/N/Exo and LN428/Res/Exo are rich in the proteins related with nucleosome assembly, microtubule-based process and chromatin silencing. In conclusion, U251/N/Exo sensitizes LN428 cells to resveratrol via delivering drug sensitizing signals, suggesting the presence of additional factor(s) that may determine the resveratrol sensitivities of glioblastoma cells.

Patient-Derived Induced Pluripotent Stem Cells and Organoids for Modeling Alpha Synuclein Propagation in Parkinson's Disease

Parkinson's disease (PD) is an age-associated, progressive neurodegenerative disorder characterized by motor impairment and in some cases cognitive decline. Central to the disease pathogenesis of PD is a small, presynaptic neuronal protein known as alpha synuclein (a-syn), which tends to accumulate and aggregate in PD brains as Lewy bodies or Lewy neurites. Numerous in vitro and in vivo studies confirm that a-syn aggregates can be propagated from diseased to healthy cells, and it has been suggested that preventing the spread of pathogenic a-syn species can slow PD progression. In this review, we summarize the works of recent literature elucidating mechanisms of a-syn propagation, and discussed the advantages in using patient-derived induced pluripotent stem cells (iPSCs) and/or induced neurons to study a-syn transmission.

α-Synuclein disrupts the anti-inflammatory role of Drd2 via interfering β-arrestin2-TAB1 interaction in astrocytes

Background

α-Synuclein (α-Syn)-induced neuroinflammation plays a crucial role in the pathogenesis of Parkinson’s disease (PD). Dopamine D2 receptor (Drd2) has been regarded as a potential anti-inflammatory target in the therapy of neurodegenerative diseases. However, the effect of astrocytic Drd2 in α-Syn-induced neuroinflammation remains unclear.

Methods

The effect of Drd2 on neuroinflammation was examined in mouse primary astrocyte in vitro and A53T transgenic mice in vivo. The inflammatory responses of astrocyte were detected using immunofluorescence, ELISA, and qRT-PCR. The details of molecular mechanism were assessed using Western blotting and protein-protein interaction assays.

Results

We showed that the selective Drd2 agonist quinpirole suppressed inflammation in the midbrain of wild-type mice, but not in α-Syn-overexpressed mice. We also found that Drd2 agonists significantly alleviated LPS-induced inflammatory response in astrocytes, but failed to suppress α-Syn-induced inflammatory response. The anti-inflammation effect of Drd2 was dependent on β-arrestin2-mediated signaling, but not classical G protein pathway. α-Syn reduced the expression of β-arrestin2 in astrocytes. Increased the β-arrestin2 expression restored in the anti-inflammation of Drd2 in α-Syn-induced inflammation. Furthermore, we demonstrated that α-Syn disrupted the anti-inflammation of Drd2 via inhibiting the association of β-arrestin2 with transforming growth factor-beta-activated kinase 1 (TAK1)-binding protein 1 (TAB1) and promoting TAK1-TAB1 interaction in astrocytes.

Conclusions

Our study illustrates that astrocytic Drd2 inhibits neuroinflammation through a β-arrestin2-dependent mechanism and provides a new strategy for treatment of PD. Our findings also reveal that α-Syn disrupts the function of β-arrestin2 and inflammatory pathways in the pathogenesis of PD.

Topical heat shock protein 70 prevents imiquimod-induced psoriasis-like inflammation in mice

Psoriasis is a chronic inflammatory skin disease with systemic manifestations and potential genetic etiology. The newest treatments utilize antibodies against one of several cytokines known to underlie the inflammatory signaling molecules that produce the skin and systemic symptoms. However, these agents must be regularly injected, and they may compromise the normal responses of the immune system. Furthermore, they do not address the causes of the abnormal immunoregulatory responses of the disease because the etiology is not yet completely understood. In this short-term treatment study, the potential anti-inflammatory activity of an alfalfa-derived Hsp70-containing skin cream (aHsp70) was tested on imiquimod (IMQ)-induced psoriasis-like lesions in wild-type mice. Treatment of the mice with the aHsp70 skin cream simultaneously with the imiquimod application mitigated the induction of psoriatic-like lesions and correlated with altered expression of various skin cytokines.

Role of CXCR1 and Interleukin-8 in Methamphetamine-Induced Neuronal Apoptosis

Methamphetamine (METH), an extremely and widely abused illicit drug, can cause serious nervous system damage and social problems. Previous research has shown that METH use causes dopaminergic neuron apoptosis and astrocyte-related neuroinflammation. However, the relationship of astrocytes and neurons in METH-induced neurotoxicity remains unclear. We hypothesized that chemokine interleukin (IL) eight released by astrocytes and C-X-C motif chemokine receptor 1 (CXCR1) in neurons are involved in METH-induced neuronal apoptosis. We tested our hypothesis by examining the changes of CXCR1 in SH-SY5Y cells and in the brain of C57BL/6 mice exposed to METH by western blotting and immunolabeling. We also determined the effects of knocking down CXCR1 expression with small interfering ribonucleic acid (siRNA) on METH-exposed SH-SY5Y cells. Furthermore, we detected the expression levels of IL-8 and the nuclear factor-kappa B (NF-κB) pathway in U87MG cells and then co-cultured the two cell types to determine the role of CXCR1 and IL-8 in neuronal apoptosis. Our results indicated that METH exposure increased CXCR1 expression both in vitro and in vivo, with the effects obtained in vitro being dose-dependent. Silencing of CXCR1 expression with siRNAs reduced the expression of cleaved caspase-3, cleaved poly (ADP-ribose) polymerase (PARP), and other related proteins. In addition, IL-8 expression and release were increased in METH-exposed U87MG cells, which is regulated by NF-κB pathway. Neuronal apoptosis was attenuated by siCXCR1 after METH treatment in the co-cultured cells, which can be reversed after exposure to recombinant IL-8. These results demonstrate that CXCR1 plays an important role in neuronal apoptosis induced by METH and may be a potential target for METH-induced neurotoxicity therapy. Highlights -Methamphetamine exposure upregulated the expression of CXCR1.-Methamphetamine exposure increased the expression of interleukin-8 through nuclear factor-kappa B pathway.-Activation of CXCR1 by interleukin-8 induces an increase in methamphetamine-related neuronal apoptosis.

α-Synuclein activates innate immunity but suppresses interferon-γ expression in murine astrocytes

Glial activation and neuroinflammation contribute to pathogenesis of neurodegenerative diseases, linked to neuron loss and dysfunction. α-Synuclein (α-syn), as a metabolite of neuron, can induce microglia activation to trigger innate immune response. However, whether α-syn, as well as its mutants (A53T, A30P, and E46K), induces astrocyte activation and inflammatory response is not fully elucidated. In this study, we used A53T mutant and wild-type α-syns to stimulate primary astrocytes in dose- and time-dependent manners (0.5, 2, 8, and 20 μg/ml for 24 hr or 3, 12, 24, and 48 hr at 2 μg/ml), and evaluated activation of several canonical inflammatory pathway components. The results showed that A53T mutant or wild-type α-syn significantly upregulated mRNA expression of toll-like receptor (TLR)2, TLR3, nuclear factor-κB and interleukin (IL)-1β, displaying a pattern of positive dose-effect correlation or negative time-effect correlation. Such upregulation was confirmed at protein levels of TLR2 (at 20 μg/ml), TLR3 (at most doses), and IL-1β (at 3 hr) by western blotting. Blockage of TLR2 other than TLR4 inhibited TLR3 and IL-1β mRNA expressions. By contrast, interferon (IFN)-γ was significantly downregulated at mRNA, protein, and protein release levels, especially at high concentrations of α-syns or early time-points. These findings indicate that α-syn was a TLRs-mediated immunogenic agent (A53T mutant stronger than wild-type α-syn). The stimulation patterns suggest that persistent release and accumulation of α-syn is required for the maintenance of innate immunity activation, and IFN-γ expression inhibition by α-syn suggests a novel immune molecule interaction mechanism underlying pathogenesis of neurodegenerative diseases.