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Guo Y, Song J, Yan M, Chen Y, Huang L, Liu J, He Y, Lü Y, Yu W. The role of NLRP6 in the development and progression of neurological diseases. Mol Biol Rep 2024; 51:351. [PMID: 38400865 DOI: 10.1007/s11033-024-09293-z] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/11/2023] [Accepted: 01/29/2024] [Indexed: 02/26/2024]
Abstract
The nervous system possesses the remarkable ability to undergo changes in order to store information; however, it is also susceptible to damage caused by invading pathogens or neurodegenerative processes. As a member of nucleotide-binding oligomerization domain-like receptor (NLR) family, the NLRP6 inflammasome serves as a cytoplasmic innate immune sensor responsible for detecting microbe-associated molecular patterns. Upon activation, NLRP6 can recruit the adapter protein apoptosis-associated speck-like protein (ASC) and the inflammatory factors caspase-1 or caspase-11. Consequently, inflammasomes are formed, facilitating the maturation and secretion of pro-inflammatory cytokines such as inflammatory factors-18 (IL-18) and inflammatory factors-1β (IL-1β). Precise regulation of NLRP6 is crucial for maintaining tissue homeostasis, as dysregulated inflammasome activation can contribute to the development of various diseases. Furthermore, NLRP6 may also play a role in the regulation of extraintestinal diseases. In cells of the brain, such as astrocytes and neurons, NLRP6 inflammasome are also present. Here, the assembly and subsequent activation of caspase-1 mediated by NLRP6 contribute to disease progression. This review aims to discuss the structure and function of NLRP6, explain clearly the mechanisms that induce and activate NLRP6, and explore its role within the central and peripheral nervous system.
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Affiliation(s)
- Yiming Guo
- Institute of Neuroscience, Chongqing Medical University, No. 1, Yixuayuan Road, Yuzhong District, Chongqing, 400016, China
| | - Jiaqi Song
- Institute of Neuroscience, Chongqing Medical University, No. 1, Yixuayuan Road, Yuzhong District, Chongqing, 400016, China
| | - Mengyu Yan
- Institute of Neuroscience, Chongqing Medical University, No. 1, Yixuayuan Road, Yuzhong District, Chongqing, 400016, China
| | - Yingxi Chen
- Institute of Neuroscience, Chongqing Medical University, No. 1, Yixuayuan Road, Yuzhong District, Chongqing, 400016, China
| | - Lihong Huang
- Institute of Neuroscience, Chongqing Medical University, No. 1, Yixuayuan Road, Yuzhong District, Chongqing, 400016, China
| | - Jiarui Liu
- Department of Geriatrics, The First Affiliated Hospital of Chongqing Medical University, Chongqing, 400016, China
| | - Yurou He
- Institute of Neuroscience, Chongqing Medical University, No. 1, Yixuayuan Road, Yuzhong District, Chongqing, 400016, China
| | - Yang Lü
- Department of Geriatrics, The First Affiliated Hospital of Chongqing Medical University, Chongqing, 400016, China
| | - Weihua Yu
- Institute of Neuroscience, Chongqing Medical University, No. 1, Yixuayuan Road, Yuzhong District, Chongqing, 400016, China.
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Yalçın MB, Bora ES, Çakır A, Akbulut S, Erbaş O. Autophagy and anti-inflammation ameliorate diabetic neuropathy with Rilmenidine. Acta Cir Bras 2023; 38:e387823. [PMID: 38055406 DOI: 10.1590/acb387823] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/26/2023] [Accepted: 09/25/2023] [Indexed: 12/08/2023] Open
Abstract
PURPOSE To evaluate the neuroprotective effects of Rilmenidine on diabetic peripheral neuropathy (DPN) in a rat model of diabetes induced by streptozotocin (STZ). METHODS STZ (60 mg/kg) was administered to adult Sprague-Dawley rats to induce diabetes. On the 30th day after STZ administration, electromyography (EMG) and motor function tests confirmed the presence of DPN. Group 1: Control (n = 10), Group 2: DM + 0.1 mg/kg Rilmenidine (n = 10), and Group 3: DM + 0.2 mg/kg Rilmenidine (n = 10) were administered via oral lavage for four weeks. EMG, motor function test, biochemical analysis, and histological and immunohistochemical analysis of sciatic nerves were then performed. RESULTS The administration of Rilmenidine to diabetic rats substantially reduced sciatic nerve inflammation and fibrosis and prevented electrophysiological alterations. Immunohistochemistry of sciatic nerves from saline-treated rats revealed increased perineural thickness, HMGB-1, tumor necrosis factor-α, and a decrease in nerve growth factor (NGF), LC-3. In contrast, Rilmendine significantly inhibited inflammation markers and prevented the reduction in NGF expression. In addition, Rilmenidine significantly decreased malondialdehyde and increased diabetic rats' total antioxidative capacity. CONCLUSIONS The findings of this study suggest that Rilmenidine may have therapeutic effects on DNP by modulating antioxidant and autophagic pathways.
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Affiliation(s)
- Mehmet Burak Yalçın
- Bahcelievler Memorial Hospital - Department of Orthopedics and Traumatology - Istanbul - Turkey
| | - Ejder Saylav Bora
- Izmir Ataturk Research and Training Hospital - Department of Emergency Medicine - Izmir - Turkey
| | - Adem Çakır
- Canakkale Mehmet Akif Ersoy State SBU Kartal Kosuyolu Training and Research Hospital - Department of Emergency Medicine - Canakkale - Turkey
| | - Sabiye Akbulut
- SBU Kartal Kosuyolu Training and Research - Hospital Department of Gastroenterology - Istanbul - Turkey
| | - Oytun Erbaş
- Demiroğlu Bilim University - Faculty of Medicine - Department of Physiology - Istanbul - Turkey
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Yao D, Wang Y, Chen Y, Chen G. The Analgesia Effect of Aucubin on CFA-Induced Inflammatory Pain by Inhibiting Glial Cells Activation-Mediated Inflammatory Response via Activating Mitophagy. Pharmaceuticals (Basel) 2023; 16:1545. [PMID: 38004411 PMCID: PMC10674556 DOI: 10.3390/ph16111545] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/18/2023] [Revised: 10/10/2023] [Accepted: 10/30/2023] [Indexed: 11/26/2023] Open
Abstract
BACKGROUND Inflammatory pain, characterized by sustained nociceptive hypersensitivity, represents one of the most prevalent conditions in both daily life and clinical settings. Aucubin, a natural plant iridoid glycoside, possesses potent biological effects, encompassing anti-inflammatory, antioxidant, and neuroprotective properties. However, its impact on inflammatory pain remains unclear. The aim of this study is to investigate the therapeutic effects and underlying mechanism of aucubin in addressing inflammatory pain induced by complete Freund's adjuvant (CFA). METHODS The CFA-induced inflammatory pain model was employed to assess whether aucubin exerts analgesic effects and its potential mechanisms. Behavioral tests evaluated mechanical and thermal hyperalgesia as well as anxiety-like behaviors in mice. The activation of spinal glial cells and the expression of pro-inflammatory cytokines were examined to evaluate neuroinflammation. Additionally, RNA sequencing was utilized for the identification of differentially expressed genes (DEGs). Molecular biology experiments were conducted to determine the levels of the PINK1 gene and autophagy-related genes, along with PINK1 distribution in neural cells. Furthermore, mitophagy induced by carbonyl cyanide m-chlorophenylhydrazone (CCCP) was employed to examine the roles of PINK1 and mitophagy in pain processing. RESULTS Aucubin significantly ameliorated pain and anxiety-like behaviors induced by CFA in mice and reduced spinal inflammation. RNA sequencing indicated PINK1 as a pivotal gene, and aucubin treatment led to a significant downregulation of PINK1 expression. Further GO and KEGG analyses suggested the involvement of mitochondrial function in the therapeutic regulation of aucubin. Western blotting revealed that aucubin markedly decreased PINK1, Parkin, and p62 levels while increasing LC3B expression. Immunofluorescence showed the predominant co-localization of PINK1 with neuronal cells. Moreover, CCCP-induced mitophagy alleviated mechanical and thermal hyperalgesia caused by CFA and reversed CFA-induced mitochondrial dysfunction. CONCLUSIONS In summary, our data suggest that aucubin effectively alleviates CFA-induced inflammatory pain, potentially through triggering the PINK1 pathway, promoting mitophagy, and suppressing inflammation. These results provide a novel theoretical foundation for addressing the treatment of inflammatory pain.
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Affiliation(s)
- Dandan Yao
- Department of Anesthesiology, Sir Run Run Shaw Hospital, School of Medicine, Zhejiang University, Hangzhou 310058, China
- Department of Anesthesiology, School of Medicine, Shaoxing University, Shaoxing 312000, China
| | - Yongjie Wang
- Key Laboratory of Elemene Class Anti-Cancer Chinese Medicines, Engineering Laboratory of Development and Application of Traditional Chinese Medicines, Collaborative Innovation Center of Traditional Chinese Medicines of Zhejiang Province, Hangzhou Normal University, Hangzhou 311121, China
| | - Yeru Chen
- Department of Anesthesiology, Sir Run Run Shaw Hospital, School of Medicine, Zhejiang University, Hangzhou 310058, China
| | - Gang Chen
- Department of Anesthesiology, Sir Run Run Shaw Hospital, School of Medicine, Zhejiang University, Hangzhou 310058, China
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Zheng G, Ren J, Shang L, Bao Y. Role of autophagy in the pathogenesis and regulation of pain. Eur J Pharmacol 2023; 955:175859. [PMID: 37429517 DOI: 10.1016/j.ejphar.2023.175859] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/02/2023] [Revised: 06/08/2023] [Accepted: 06/15/2023] [Indexed: 07/12/2023]
Abstract
Pain is a ubiquitous and highly concerned clinical symptom, usually caused by peripheral or central nervous injury, tissue damage, or other diseases. The long-term existence of pain can seriously affect daily physical function and quality of life and produce great torture on the physiological and psychological levels. However, the complex pathogenesis of pain involving molecular mechanisms and signaling pathways has not been fully elucidated, and managing pain remains highly challenging. As a result, finding new targets to pursue effective and long-term pain treatment strategies is required and urgent. Autophagy is an intracellular degradation and recycling process that maintains tissue homeostasis and energy supply, which can be cytoprotective and is vital in maintaining neural plasticity and proper nervous system function. Much evidence has shown that autophagy dysregulation is linked to the emergence of neuropathic pain, such as postherpetic neuralgia and cancer-related pain. Autophagy has also been connected to pain caused by osteoarthritis and lumbar disc degeneration. It is worth noting that in recent years, studies on traditional Chinese medicine have also proved that several traditional Chinese medicine monomers involve autophagy in the mechanism of pain relief. Therefore, autophagy can serve as a potential regulatory target to provide new ideas and inspiration for pain management.
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Affiliation(s)
- Guangda Zheng
- Department of Oncology, Guang'anmen Hospital, China Academy of Chinese Medical Sciences, Beijing, 100053, China.
| | - Juanxia Ren
- Liaoning University of Traditional Chinese Medicine, Shenyang, 110847, Liaoning Province, China.
| | - Lu Shang
- Liaoning University of Traditional Chinese Medicine, Shenyang, 110847, Liaoning Province, China.
| | - Yanju Bao
- Department of Oncology, Guang'anmen Hospital, China Academy of Chinese Medical Sciences, Beijing, 100053, China.
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Jaiswar P, Bhate M, Surolia A. Promotion of degradative autophagy by 6-bromoindirubin-3'-oxime attenuates neuropathy. Biofactors 2023; 49:1074-1084. [PMID: 37249268 DOI: 10.1002/biof.1977] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 12/02/2022] [Accepted: 04/20/2023] [Indexed: 05/31/2023]
Abstract
Damage to the central or peripheral nervous system causes neuropathic pain. Endoplasmic reticulum (ER) stress plays a role in peripheral neuropathy. Increase in ER stress is seen in diabetic neuropathy. Inducers of ER stress also give rise to peripheral neuropathy. ER stress leads to the formation of autophagosome but as their degradation is also stalled during ER stress accumulation of autophagosomes is seen. Accumulation of autophagosomes has deleterious effects on cells. In the present study, we show that treatment with tunicamycin (TM) (ER stress inducer) in mice leads to peripheral neuropathy as assessed by Von Frey and Hot plate method. Administration of a promoter of autophagy viz. 6-bromoindirubin-3'-oxime (6-BIO) subsequent to ER stress induced by TM exhibits a decrease in peripheral neuropathy. 6-BIO was also effective in reducing diabetic peripheral neuropathy. To understand the type of autophagy activated, SH-SY5Y cells were treated with 6-BIO after TM treatment. Levels of cathepsin D (CTSD), a marker for degradative autophagy was higher in cells treated with 6-BIO after TM treatment compared to only TM-treated SH-SY5Y cells while levels of Rab8A,-a marker for secretory autophagy was reduced. Furthermore, in parallel during ER stress secretory, we noted increased levels of lysozyme in autophagosomes destined for secretion. Cells treated with 6-BIO showed reduction of lysozyme in secretory autophagosomes. This shows that 6-BIO increased degradative autophagy and reduced the secretory autophagy. 6-BIO also reduced the caspase-3 activity in 6-BIO-treated cells. Thus, 6-BIO reduced neuropathy in animals by activating degradative autophagy and reducing the secretory autophagy.
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Affiliation(s)
- Praveen Jaiswar
- Molecular Biophysics Unit, Indian Institute of Science, Bangalore, India
| | - Mitali Bhate
- Molecular Biophysics Unit, Indian Institute of Science, Bangalore, India
| | - Avadhesha Surolia
- Molecular Biophysics Unit, Indian Institute of Science, Bangalore, India
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Liu X, Zhao S, Zhao Q, Chen Y, Jia S, Xiang R, Zhang J, Sun J, Xu Y, Zhao M. Butein, a potential drug for the treatment of bone cancer pain through bioinformatic and network pharmacology. Toxicol Appl Pharmacol 2023; 472:116570. [PMID: 37268026 DOI: 10.1016/j.taap.2023.116570] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/04/2022] [Revised: 05/23/2023] [Accepted: 05/26/2023] [Indexed: 06/04/2023]
Abstract
Bone cancer pain is a difficult-to-treat pathologic condition that impairs the patient's quality of life. The effective therapy options for BCP are restricted due to the unknown pathophysiology. Transcriptome data were obtained from the Gene Expression Omnibus database and differentially expressed gene extraction was performed. DEGs integrated with pathological targets found 68 genes in the study. Butein was discovered as a possible medication for BCP after the 68 genes were submitted to the Connectivity Map 2.0 database for drug prediction. Moreover, butein has good drug-likeness properties. To collect the butein targets, we used the CTD, SEA, TargetNet, and Super-PRED databases. Furthermore, Kyoto Encyclopedia of Genes and Genomes pathway enrichment analyses revealed butein's pharmacological effects, indicating that butein may aid in treating BCP by altering the hypoxia-inducible factor, NF-kappa B, angiogenesis, and sphingolipid signaling pathways. Moreover, the pathological targets integrated with drug targets were obtained as the shared gene set A, which was analyzed by ClueGO and MCODE. Biological process analysis and MCODE algorithm further analyzed that BCP related targets were mainly involved in signal transduction process and ion channel-related pathways. Next, we integrated targets related to network topology parameters and targets of core pathways, identified PTGS2, EGFR, JUN, ESR1, TRPV1, AKT1 and VEGFA as butein regulated hub genes by molecular docking, which play a critical role in its analgesic effect. This study lays the scientific groundwork for elucidating the mechanism underlying butein's success in the treatment of BCP.
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Affiliation(s)
- Xin Liu
- School of Life Sciences and Biopharmaceutical Science, Shenyang Pharmaceutical University, Shenyang 110016, PR China
| | - Shangfeng Zhao
- School of Life Sciences and Biopharmaceutical Science, Shenyang Pharmaceutical University, Shenyang 110016, PR China
| | - Qianqian Zhao
- School of Life Sciences and Biopharmaceutical Science, Shenyang Pharmaceutical University, Shenyang 110016, PR China
| | - Yiwei Chen
- School of Life Sciences and Biopharmaceutical Science, Shenyang Pharmaceutical University, Shenyang 110016, PR China
| | - Shubing Jia
- School of Life Sciences and Biopharmaceutical Science, Shenyang Pharmaceutical University, Shenyang 110016, PR China
| | - Rongwu Xiang
- School of Medical Devices, Shenyang Pharmaceutical University, Shenyang 110016, PR China
| | - Jinghai Zhang
- School of Medical Devices, Shenyang Pharmaceutical University, Shenyang 110016, PR China
| | - Jianfang Sun
- School of Life Sciences and Biopharmaceutical Science, Shenyang Pharmaceutical University, Shenyang 110016, PR China
| | - Yijia Xu
- School of Life Sciences and Biopharmaceutical Science, Shenyang Pharmaceutical University, Shenyang 110016, PR China.
| | - Mingyi Zhao
- School of Life Sciences and Biopharmaceutical Science, Shenyang Pharmaceutical University, Shenyang 110016, PR China.
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Qiu XT, Guo C, Ma LT, Li XN, Zhang QY, Huang FS, Zhang MM, Bai Y, Liang GB, Li YQ. Transcriptomic and proteomic profiling of the anterior cingulate cortex in neuropathic pain model rats. Front Mol Neurosci 2023; 16:1164426. [PMID: 37396788 PMCID: PMC10311218 DOI: 10.3389/fnmol.2023.1164426] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/12/2023] [Accepted: 05/25/2023] [Indexed: 07/04/2023] Open
Abstract
Background Neuropathic pain (NP) takes a heavy toll on individual life quality, yet gaps in its molecular characterization persist and effective therapy is lacking. This study aimed to provide comprehensive knowledge by combining transcriptomic and proteomic data of molecular correlates of NP in the anterior cingulate cortex (ACC), a cortical hub responsible for affective pain processing. Methods The NP model was established by spared nerve injury (SNI) in Sprague-Dawley rats. RNA sequencing and proteomic data from the ACC tissue isolated from sham and SNI rats 2 weeks after surgery were integrated to compare their gene and protein expression profiles. Bioinformatic analyses were performed to figure out the functions and signaling pathways of the differentially expressed genes (DEGs) and differentially expressed proteins (DEPs) enriched in. Results Transcriptomic analysis identified a total of 788 DEGs (with 49 genes upregulated) after SNI surgery, while proteomic analysis found 222 DEPs (with 89 proteins upregulated). While Gene Ontology and Kyoto Encyclopedia of Genes and Genomes enrichment analyses of the DEGs suggested that most of the altered genes were involved in synaptic transmission and plasticity, bioinformatics analysis of the DEPs revealed novel critical pathways associated with autophagy, mitophagy, and peroxisome. Notably, we noticed functionally important NP-related changes in the protein that occurred in the absence of corresponding changes at the level of transcription. Venn diagram analysis of the transcriptomic and proteomic data identified 10 overlapping targets, among which only three genes (XK-related protein 4, NIPA-like domain-containing 3, and homeodomain-interacting protein kinase 3) showed concordance in the directions of change and strong correlations between mRNA and protein levels. Conclusion The present study identified novel pathways in the ACC in addition to confirming previously reported mechanisms for NP etiology, and provided novel mechanistic insights for future research on NP treatment. These findings also imply that mRNA profiling alone fails to provide a complete landscape of molecular pain in the ACC. Therefore, explorations of changes at the level of protein are necessary to understand NP processes that are not transcriptionally modulated.
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Affiliation(s)
- Xin-Tong Qiu
- Department of Anatomy, Histology and Embryology, Preclinical School of Medicine, Air Force Medical University, Xi’an, China
| | - Chen Guo
- Department of Neurosurgery, General Hospital of Northern Theater Command, Shenyang, China
| | - Li-Tian Ma
- Department of Gastroenterology, Tangdu Hospital, Air Force Medical University, Xi'an, China
| | - Xin-Ning Li
- Department of Neurosurgery, General Hospital of Northern Theater Command, Shenyang, China
| | - Qi-Yan Zhang
- Department of Neurosurgery, General Hospital of Northern Theater Command, Shenyang, China
| | - Fen-Sheng Huang
- Institute of Neuroscience and Physiology, University of Göteborg, Göteborg, Sweden
| | - Ming-Ming Zhang
- Department of Anatomy, Histology and Embryology, Preclinical School of Medicine, Air Force Medical University, Xi’an, China
| | - Yang Bai
- Department of Neurosurgery, General Hospital of Northern Theater Command, Shenyang, China
| | - Guo-Biao Liang
- Department of Neurosurgery, General Hospital of Northern Theater Command, Shenyang, China
| | - Yun-Qing Li
- Department of Anatomy, Histology and Embryology, Preclinical School of Medicine, Air Force Medical University, Xi’an, China
- Department of Geriatrics, Tangdu Hospital, Air Force Medical University, Xi’an, China
- Department of Human Anatomy, Basic Medical College, Zunyi Medical University, Zunyi, China
- Department of Anatomy, College of Basic Medicine, Dali University, Dali, China
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Zargani M, Ramirez-Campillo R, Arabzadeh E. Swimming and L-arginine loaded chitosan nanoparticles ameliorates aging-induced neuron atrophy, autophagy marker LC3, GABA and BDNF-TrkB pathway in the spinal cord of rats. Pflugers Arch 2023; 475:621-635. [PMID: 36869900 DOI: 10.1007/s00424-023-02795-y] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/04/2022] [Revised: 01/05/2023] [Accepted: 02/08/2023] [Indexed: 03/05/2023]
Abstract
Aging is associated with muscle atrophy, and erosion and destruction of neuronal pathways in the spinal cord. The study aim was to assess the effect of swimming training (Sw) and L-arginine loaded chitosan nanoparticles (LA-CNPs) on the sensory and motor neuron population, autophagy marker LC3, total oxidant status/total antioxidant capacity, behavioural test, GABA and BDNF-TrkB pathway in the spinal cord of aging rats. The rats were randomized to five groups: young (8-weeks) control (n = 7), old control (n = 7), old Sw (n = 7), old LA-CNPs (n = 7) and old Sw + LA-CNPs (n = 7). Groups under LA-CNPs supplementation received 500 mg/kg/day. Sw groups performed a swimming exercise programme 5 days per week for 6 weeks. Upon the completion of the interventions the rats were euthanized and the spinal cord was fixed and frozen for histological assessment, IHC, and gene expression analysis. The old group had more atrophy in the spinal cord with higher changes in LC3 as an indicator of autophagy in the spinal cord compared to the young group (p < 0.0001). The old Sw + LA-CNPs group increased (improved) spinal cord GABA (p = 0.0187), BDNF (p = 0.0003), TrkB (p < 0.0001) gene expression, decreased autophagy marker LC3 protein (p < 0.0001), nerve atrophy and jumping/licking latency (p < 0.0001), improved sciatic functional index score and total oxidant status/total antioxidant capacity compared to the old group (p < 0.0001). In conclusion, swimming and LA-CNPs seems to ameliorate aging-induced neuron atrophy, autophagy marker LC3, oxidant-antioxidant status, functional restoration, GABA and BDNF-TrkB pathway in the spinal cord of aging rats. Our study provides experimental evidence for a possible positive role of swimming and L-arginine loaded chitosan nanoparticles to decrease complications of aging.
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Affiliation(s)
- Mehdi Zargani
- Department of Exercise Physiology, Karaj Branch, Islamic Azad University, Karaj, Iran
| | - Rodrigo Ramirez-Campillo
- Exercise and Rehabilitation Sciences Laboratory, School of Physical Therapy, Faculty of Rehabilitation Sciences, Universidad Andres Bello, 7591538, Santiago, Chile
| | - Ehsan Arabzadeh
- Exercise Physiology Research Center, Life Style Institute, Baqiyatallah University of Medical Sciences, Tehran, Iran.
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Mei X, Yin C, Pan Y, Chen L, Wu C, Li X, Feng Z. The role of ectopic P granules protein 5 homolog (EPG5) in DHPG-induced pain sensitization in mice. J Neurochem 2023; 165:196-210. [PMID: 36748629 DOI: 10.1111/jnc.15779] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/01/2022] [Revised: 01/29/2023] [Accepted: 02/01/2023] [Indexed: 02/08/2023]
Abstract
Nociplastic pain is a severe health problem, while its mechanisms are still unclear. (R, S)-3,5-Dihydroxyphenylglycine (DHPG) is a group I metabotropic glutamate receptor (mGluR) agonist that can cause central sensitization, which plays a role in nociplastic pain. In this study, after intrathecal injection of 25 nmol DHPG for three consecutive days, whole proteins were extracted from the L4~6 lumbar spinal cord of mice 2 h after intrathecal administration on the third day for proteomics analysis. Based on the results, 15 down-regulated and 20 up-regulated proteins were identified in mice. Real-time quantitative PCR (RT-qPCR) and western blotting (WB) revealed that the expression of ectopic P granules protein 5 homolog (EPG5) mRNA and protein were significantly up-regulated compared with the control group, which was consistent with the proteomics results. Originally identified in the genetic screening of Caenorhabditis elegans, EPG5 is mainly involved in regulating autophagy in the body, and in our study, it was mainly expressed in spinal neurons, as revealed by immunohistochemistry staining. After the intrathecal injection of 8 μL adeno-associated virus (AAV)-EPG5 short hairpin RNA (shRNA) to knock down spinal EPG5, the hyperalgesia caused by DHPG was relieved. Altogether, these results suggest that EPG5 plays an important role in DHPG-induced pain sensitization in mice.
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Affiliation(s)
- Xiangyang Mei
- Department of Pain Medicine, The First Affiliated Hospital, Zhejiang University School of Medicine, Hangzhou, China
| | - Chengyu Yin
- Department of Neurobiology and Acupuncture Research, The Third Clinical Medical College, Zhejiang Chinese Medical University, Key Laboratory of Acupuncture and Neurology of Zhejiang Province, Hangzhou, China
| | - Yushuang Pan
- Department of Neurobiology and Acupuncture Research, The Third Clinical Medical College, Zhejiang Chinese Medical University, Key Laboratory of Acupuncture and Neurology of Zhejiang Province, Hangzhou, China
| | - Lei Chen
- Department of Pain Medicine, The First Affiliated Hospital, Zhejiang University School of Medicine, Hangzhou, China
| | - Cheng Wu
- Institute of Neuroscience, Key Laboratory of Medical Neurobiology of the Ministry of Health of China, School of Medicine, Zhejiang University, Hangzhou, China
| | - Xiangyao Li
- Institute of Neuroscience, Key Laboratory of Medical Neurobiology of the Ministry of Health of China, School of Medicine, Zhejiang University, Hangzhou, China
| | - Zhiying Feng
- Department of Pain Medicine, The First Affiliated Hospital, Zhejiang University School of Medicine, Hangzhou, China
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Mesenchymal stem cell-derived extracellular vesicles carrying miR-99b-3p restrain microglial activation and neuropathic pain by stimulating autophagy. Int Immunopharmacol 2023; 115:109695. [PMID: 36638658 DOI: 10.1016/j.intimp.2023.109695] [Citation(s) in RCA: 9] [Impact Index Per Article: 9.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/17/2022] [Revised: 12/19/2022] [Accepted: 01/03/2023] [Indexed: 01/13/2023]
Abstract
Neuropathic pain is a complex condition that seriously affects human quality of life. This study aimed to investigate the therapeutic mechanism of mesenchymal stem cell-derived extracellular vesicles (MSC-EVs) and try to discover new targets for alleviating neuropathic pain. Extracellular vesicles were isolated and identified via ultracentrifugation. BV-2 microglial cells were stimulated with lipopolysaccharide (LPS) in the presence or absence of MSC-EVs. Further, microglial activation and neuroinflammation were evaluated by flow cytometry, RT-qPCR, and ELISA. High-throughput sequencing analysis was performed to reveal the differentially expressed (DE) miRNAs in BV-2 microglia. Autophagy-related regulators were assessed by Western blotting and Immunofluorescence staining. Chronic constriction injury (CCI) model was used to induce neuropathic pain in rats, and the mechanical withdrawal threshold (MWT) was measured. High-throughput sequencing analysis identified 17 DE miRNAs, which were mainly enriched in PI3K-AKT and mTOR signaling pathways. MSC-EVs inhibited the activation of PI3K/AKT/mTOR signaling pathway in LPS-stimulated microglia. Moreover, MSC-EVs treatment enhanced the autophagy level in activated microglia, whereas autophagy inhibitor 3-MA reversed the suppressing effects of MSC-EVs on microglial activation and neuroinflammation. The MSC-EV-mediated transfer of miR-99b-3p was verified to promote microglial autophagy, and miR-99b-3p overexpression suppressed the expression of pro-inflammatory factors in activated microglia. During in vivo studies, intrathecal injection of MSC-EVs significantly up-regulated the expression of miR-99b-3p, and alleviated mechanical allodynia caused by activated microglia in the spinal cord dorsal horn of CCI rats. Moreover, MSC-EVs treatment repaired CCI-induced autophagic impairment by stimulating autophagy in the spinal cord. Collectively, our findings demonstrated that MSC-EVs had an analgesic effect on neuropathic pain via promoting autophagy, and these antinociceptive effects were at least in part caused by MSC-EV-mediated transfer of miR-99b-3p, thereby inhibiting microglial activation and pro-inflammatory cytokines expression.
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Liao MF, Lu KT, Hsu JL, Lee CH, Cheng MY, Ro LS. The Role of Autophagy and Apoptosis in Neuropathic Pain Formation. Int J Mol Sci 2022; 23:ijms23052685. [PMID: 35269822 PMCID: PMC8910267 DOI: 10.3390/ijms23052685] [Citation(s) in RCA: 17] [Impact Index Per Article: 8.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/29/2021] [Revised: 02/26/2022] [Accepted: 02/27/2022] [Indexed: 01/18/2023] Open
Abstract
Neuropathic pain indicates pain caused by damage to the somatosensory system and is difficult to manage and treat. A new treatment strategy urgently needs to be developed. Both autophagy and apoptosis are critical adaptive mechanisms when neurons encounter stress or damage. Recent studies have shown that, after nerve damage, both autophagic and apoptotic activities in the injured nerve, dorsal root ganglia, and spinal dorsal horn change over time. Many studies have shown that upregulated autophagic activities may help myelin clearance, promote nerve regeneration, and attenuate pain behavior. On the other hand, there is no direct evidence that the inhibition of apoptotic activities in the injured neurons can attenuate pain behavior. Most studies have only shown that agents can simultaneously attenuate pain behavior and inhibit apoptotic activities in the injured dorsal root ganglia. Autophagy and apoptosis can crosstalk with each other through various proteins and proinflammatory cytokine expressions. Proinflammatory cytokines can promote both autophagic/apoptotic activities and neuropathic pain formation, whereas autophagy can inhibit proinflammatory cytokine activities and further attenuate pain behaviors. Thus, agents that can enhance autophagic activities but suppress apoptotic activities on the injured nerve and dorsal root ganglia can treat neuropathic pain. Here, we summarized the evolving changes in apoptotic and autophagic activities in the injured nerve, dorsal root ganglia, spinal cord, and brain after nerve damage. This review may help in further understanding the treatment strategy for neuropathic pain during nerve injury by modulating apoptotic/autophagic activities and proinflammatory cytokines in the nervous system.
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Affiliation(s)
- Ming-Feng Liao
- Linkou Medical Center, Department of Neurology, Chang Gung Memorial Hospital, College of Medicine, Chang Gung University, Taoyuan 333, Taiwan; (M.-F.L.); (J.-L.H.); (C.-H.L.); (M.-Y.C.)
- Department of Life Science, School of Life Science, National Taiwan Normal University, Taipei 106, Taiwan;
| | - Kwok-Tung Lu
- Department of Life Science, School of Life Science, National Taiwan Normal University, Taipei 106, Taiwan;
| | - Jung-Lung Hsu
- Linkou Medical Center, Department of Neurology, Chang Gung Memorial Hospital, College of Medicine, Chang Gung University, Taoyuan 333, Taiwan; (M.-F.L.); (J.-L.H.); (C.-H.L.); (M.-Y.C.)
- Department of Neurology, New Taipei Municipal TuCheng Hospital, Chang Gung Memorial Hospital, Chang Gung University, New Taipei City 236, Taiwan
- Graduate Institute of Mind, Brain and Consciousness, Taipei Medical University, Taipei 110, Taiwan
- Brain and Consciousness Research Center, Shuang Ho Hospital, New Taipei City 235, Taiwan
| | - Chih-Hong Lee
- Linkou Medical Center, Department of Neurology, Chang Gung Memorial Hospital, College of Medicine, Chang Gung University, Taoyuan 333, Taiwan; (M.-F.L.); (J.-L.H.); (C.-H.L.); (M.-Y.C.)
| | - Mei-Yun Cheng
- Linkou Medical Center, Department of Neurology, Chang Gung Memorial Hospital, College of Medicine, Chang Gung University, Taoyuan 333, Taiwan; (M.-F.L.); (J.-L.H.); (C.-H.L.); (M.-Y.C.)
| | - Long-Sun Ro
- Linkou Medical Center, Department of Neurology, Chang Gung Memorial Hospital, College of Medicine, Chang Gung University, Taoyuan 333, Taiwan; (M.-F.L.); (J.-L.H.); (C.-H.L.); (M.-Y.C.)
- Correspondence: ; Tel.: +886-3-3281200 (ext. 8351)
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12
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Wang S, Dai Y. Roles of AMPK and Its Downstream Signals in Pain Regulation. Life (Basel) 2021; 11:life11080836. [PMID: 34440581 PMCID: PMC8401922 DOI: 10.3390/life11080836] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/09/2021] [Revised: 08/06/2021] [Accepted: 08/12/2021] [Indexed: 12/20/2022] Open
Abstract
Pain is an unpleasant sensory and emotional state that decreases quality of life. A metabolic sensor, adenosine monophosphate-activated protein kinase (AMPK), which is ubiquitously expressed in mammalian cells, has recently attracted interest as a new target of pain research. Abnormal AMPK expression and function in the peripheral and central nervous systems are associated with various types of pain. AMPK and its downstream kinases participate in the regulation of neuron excitability, neuroinflammation and axonal and myelin regeneration. Numerous AMPK activators have reduced pain behavior in animal models. The current understanding of pain has been deepened by AMPK research, but certain issues, such as the interactions of AMPK at each step of pain regulation, await further investigation. This review examines the roles of AMPK and its downstream kinases in neurons and non-neuronal cells, as well as their contribution to pain regulation.
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Affiliation(s)
- Shenglan Wang
- School of Acupuncture-Moxibustion and Tuina, Beijing University of Chinese Medicine, Beijing 100029, China
- Department of Pharmacy, School of Pharmacy, Hyogo University of Health Sciences, Kobe 650-8530, Japan
- Correspondence: (S.W.); (Y.D.); Tel.: +86-10-53912197 (S.W.); +81-78-304-3147 (Y.D.)
| | - Yi Dai
- Department of Pharmacy, School of Pharmacy, Hyogo University of Health Sciences, Kobe 650-8530, Japan
- Traditional Medicine Research Center, Chinese Medicine Confucius Institute, Hyogo College of Medicine, Kobe 663-8501, Japan
- Department of Anatomy and Neuroscience, Hyogo College of Medicine, Nishinomiya 663-8501, Japan
- Correspondence: (S.W.); (Y.D.); Tel.: +86-10-53912197 (S.W.); +81-78-304-3147 (Y.D.)
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13
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IKBKB siRNA-Encapsulated Poly (Lactic- co-Glycolic Acid) Nanoparticles Diminish Neuropathic Pain by Inhibiting Microglial Activation. Int J Mol Sci 2021; 22:ijms22115657. [PMID: 34073390 PMCID: PMC8203094 DOI: 10.3390/ijms22115657] [Citation(s) in RCA: 9] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/13/2021] [Revised: 05/19/2021] [Accepted: 05/21/2021] [Indexed: 01/08/2023] Open
Abstract
Activation of nuclear factor-kappa B (NF-κB) in microglia plays a decisive role in the progress of neuropathic pain, and the inhibitor of kappa B (IκB) is a protein that blocks the activation of NF-κB and is degraded by the inhibitor of NF-κB kinase subunit beta (IKBKB). The role of IKBKB is to break down IκB, which blocks the activity of NF-kB. Therefore, it prevents the activity of NK-kB. This study investigated whether neuropathic pain can be reduced in spinal nerve ligation (SNL) rats by reducing the activity of microglia by delivering IKBKB small interfering RNA (siRNA)-encapsulated poly (lactic-co-glycolic acid) (PLGA) nanoparticles. PLGA nanoparticles, as a carrier for the delivery of IKBKB genes silencer, were used because they have shown potential to enhance microglial targeting. SNL rats were injected with IKBKB siRNA-encapsulated PLGA nanoparticles intrathecally for behavioral tests on pain response. IKBKB siRNA was delivered for suppressing the expression of IKBKB. In rats injected with IKBKB siRNA-encapsulated PLGA nanoparticles, allodynia caused by mechanical stimulation was reduced, and the secretion of pro-inflammatory mediators due to NF-κB was reduced. Delivering IKBKB siRNA through PLGA nanoparticles can effectively control the inflammatory response and is worth studying as a treatment for neuropathic pain.
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14
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Zhu S, Ying Y, Ye J, Chen M, Wu Q, Dou H, Ni W, Xu H, Xu J. AAV2-mediated and hypoxia response element-directed expression of bFGF in neural stem cells showed therapeutic effects on spinal cord injury in rats. Cell Death Dis 2021; 12:274. [PMID: 33723238 PMCID: PMC7960741 DOI: 10.1038/s41419-021-03546-6] [Citation(s) in RCA: 30] [Impact Index Per Article: 10.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/30/2020] [Revised: 02/08/2021] [Accepted: 02/10/2021] [Indexed: 12/12/2022]
Abstract
Neural stem cell (NSCs) transplantation has been one of the hot topics in the repair of spinal cord injury (SCI). Fibroblast growth factor (FGF) is considered a promising nerve injury therapy after SCI. However, owing to a hostile hypoxia condition in SCI, there remains a challenging issue in implementing these tactics to repair SCI. In this report, we used adeno-associated virus 2 (AAV2), a prototype AAV used in clinical trials for human neuron disorders, basic FGF (bFGF) gene under the regulation of hypoxia response element (HRE) was constructed and transduced into NSCs to yield AAV2-5HRE-bFGF-NSCs. Our results showed that its treatment yielded temporally increased expression of bFGF in SCI, and improved scores of functional recovery after SCI compared to vehicle control (AAV2-5HRE-NSCs) based on the analyses of the inclined plane test, Basso-Beattie-Bresnahan (BBB) scale and footprint analysis. Mechanistic studies showed that AAV2-5HRE-bFGF-NSCs treatment increased the expression of neuron-specific neuronal nuclei protein (NeuN), neuromodulin GAP43, and neurofilament protein NF200 while decreased the expression of glial fibrillary acidic protein (GFAP) as compared to the control group. Further, the expressions of autophagy-associated proteins LC3-II and Beclin 1 were decreased, whereas the expression of P62 protein was increased in AAV2-5HRE-bFGF-NSCs treatment group. Taken together, our data indicate that AAV2-5HRE-bFGF-NSCs treatment improved the recovery of SCI rats, which is accompanied by evidence of nerve regeneration, and inhibition of SCI-induced glial scar formation and cell autophagy. Thus, this study represents a step forward towards the potential use of AAV2-5HRE-bFGF-NSCs for future clinical trials of SCI repair.
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Affiliation(s)
- Sipin Zhu
- Department of Orthopaedics, The Second Affiliated Hospital and Yuying Children's Hospital of Wenzhou Medical University, Wenzhou, 325000, Zhejiang, China.
- The Second School of Medicine, Wenzhou Medical University, 325027, Wenzhou, China.
- School of Biomedical Sciences, The University of Western Australia, Perth, WA, 6009, Australia.
| | - Yibo Ying
- Department of Orthopaedics, The Second Affiliated Hospital and Yuying Children's Hospital of Wenzhou Medical University, Wenzhou, 325000, Zhejiang, China
- The Second School of Medicine, Wenzhou Medical University, 325027, Wenzhou, China
| | - Jiahui Ye
- Department of Orthopaedics, The Second Affiliated Hospital and Yuying Children's Hospital of Wenzhou Medical University, Wenzhou, 325000, Zhejiang, China
- The Second School of Medicine, Wenzhou Medical University, 325027, Wenzhou, China
| | - Min Chen
- Department of Orthopaedics, The Second Affiliated Hospital and Yuying Children's Hospital of Wenzhou Medical University, Wenzhou, 325000, Zhejiang, China
- The Second School of Medicine, Wenzhou Medical University, 325027, Wenzhou, China
| | - Qiuji Wu
- Department of Orthopaedics, The Second Affiliated Hospital and Yuying Children's Hospital of Wenzhou Medical University, Wenzhou, 325000, Zhejiang, China
- The Second School of Medicine, Wenzhou Medical University, 325027, Wenzhou, China
| | - Haicheng Dou
- Department of Orthopaedics, The Second Affiliated Hospital and Yuying Children's Hospital of Wenzhou Medical University, Wenzhou, 325000, Zhejiang, China
| | - Wenfei Ni
- Department of Orthopaedics, The Second Affiliated Hospital and Yuying Children's Hospital of Wenzhou Medical University, Wenzhou, 325000, Zhejiang, China
| | - Huazi Xu
- Department of Orthopaedics, The Second Affiliated Hospital and Yuying Children's Hospital of Wenzhou Medical University, Wenzhou, 325000, Zhejiang, China
| | - Jiake Xu
- School of Biomedical Sciences, The University of Western Australia, Perth, WA, 6009, Australia.
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15
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NFAT5 Deficiency Alleviates Formalin-Induced Inflammatory Pain Through mTOR. Int J Mol Sci 2021; 22:ijms22052587. [PMID: 33806698 PMCID: PMC7961436 DOI: 10.3390/ijms22052587] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/04/2021] [Revised: 02/25/2021] [Accepted: 03/01/2021] [Indexed: 01/13/2023] Open
Abstract
Nuclear factor of activated T cells (NFAT5) is a well-known transcription factor that regulates the expression of genes involved in osmotic stress. However, the role of NFAT5 in inflammatory pain remains unknown. Here, we studied the function of NFAT5 in inflammatory pain using NFAT5-heterozygous (Het) mice. To study inflammatory pain, we injected 10 µL of 2% formalin into the right hind paws of mice and monitored pain behaviors, such as licking, lifting, and flinching, for 60 min. After the first 15 min (phase I), there were no significant differences in pain behaviors between wild-type (WT) and NFAT5-Het mice. However, from 15–60 min (phase II), NFAT5-Het mice displayed significantly fewer pain behaviors compared to WT mice. Further, the expression levels of inflammatory-pain-related factors, including c-Fos, phosphorylated extracellular signal-regulated kinase (p-ERK), and phosphorylated n-methyl-D-aspartate receptor subunit 2B (p-NR2B), were significantly elevated in the spinal dorsal neurons of formalin-treated WT mice but was not elevated in NFAT5-Het mice. Similarly, c-Fos, p-ERK, and p-NR2B levels were significantly higher in glutamate-treated PC12 neuronal cells but were not affected by Nfat5 silencing in glutamate-treated PC12 cells. Altogether, our findings suggest that NFAT5 deficiency may mitigate formalin-induced inflammatory pain by upregulating mammalian target of rapamycin (mTOR) expression and downregulating its downstream factors in spinal dorsal neurons. Therefore, NFAT5 is a potential therapeutic target for the treatment of inflammatory pain.
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16
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Park H, Hong J, Yin Y, Joo Y, Kim Y, Shin J, Kwon HH, Shin N, Shin HJ, Beom J, Kim DW, Kim J. TAP2, a peptide antagonist of Toll-like receptor 4, attenuates pain and cartilage degradation in a monoiodoacetate-induced arthritis rat model. Sci Rep 2020; 10:17451. [PMID: 33060735 PMCID: PMC7567100 DOI: 10.1038/s41598-020-74544-5] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/16/2020] [Accepted: 09/29/2020] [Indexed: 01/29/2023] Open
Abstract
Because inflammation in osteoarthritis (OA) is related to the Toll-like receptor 4 (TLR4) signaling cascades, TLR4 is a reasonable target for developing therapeutics for OA. Thus, we investigated whether TAP2, a peptide antagonist of TLR4, reduces the monoiodoacetate (MIA)-induced arthritic pain and cartilage degradation in rats. TLR4 expression of human OA chondrocytes and synoviocytes and the knee joint tissue of MIA-induced arthritis were evaluated. MIA-induced arthritic model using Sprague–Dawley rats (6 week-old-male) were treated with TAP2, a TLR4 antagonist, and evaluated with behavioral test, immunohistochemistry, and quantitative PCR. TLR4 was highly expressed in the knee joints of patients with OA and the MIA-induced rat model. Further, a single intraarticular injection of TAP2 (25 nmol/rat) molecules targeting TLR4 on day 7 after MIA injection dramatically attenuated pain behavior for about 3 weeks and reduced cartilage loss in the knee joints and microglial activation in the spinal dorsal horns. Likewise, the mRNA levels of TNFα and IL-1β, reactive oxygen species, and the expression of MMP13 in the knee joints of TAP2-treated rats was significantly decreased by TAP2 treatment compared with the control. Moreover, interestingly, the duration of OA pain relief by TAP2 was much longer than that of chemical TLR4 antagonists, such as C34 and M62812. In conclusion, TAP2 could effectively attenuate MIA-induced arthritis in rats by blocking TLR4 and its successive inflammatory cytokines and MMP13. Therefore, TAP2 could be a prospective therapeutic to treat patients with OA.
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Affiliation(s)
- Hyewon Park
- Department of Medical Science, Chungnam National University College of Medicine, Daejeon, Republic of Korea.,Department of Anatomy and Cell Biology, Brain Research Institute, Chungnam National University College of Medicine, Daejeon, 35015, Republic of Korea
| | - Jinpyo Hong
- Department of Neuroscience and Physiology, Dental Research Institute, Seoul National University School of Dentistry, Seoul, Republic of Korea
| | - Yuhua Yin
- Department of Medical Science, Chungnam National University College of Medicine, Daejeon, Republic of Korea.,Department of Anatomy and Cell Biology, Brain Research Institute, Chungnam National University College of Medicine, Daejeon, 35015, Republic of Korea
| | - Yongbum Joo
- Department of Orthopedics, Chungnam National University College of Medicine, Daejeon, Republic of Korea
| | - Youngmo Kim
- Department of Orthopedics, Chungnam National University College of Medicine, Daejeon, Republic of Korea
| | - Juhee Shin
- Department of Medical Science, Chungnam National University College of Medicine, Daejeon, Republic of Korea.,Department of Anatomy and Cell Biology, Brain Research Institute, Chungnam National University College of Medicine, Daejeon, 35015, Republic of Korea
| | - Hyeok Hee Kwon
- Department of Medical Science, Chungnam National University College of Medicine, Daejeon, Republic of Korea.,Department of Anatomy and Cell Biology, Brain Research Institute, Chungnam National University College of Medicine, Daejeon, 35015, Republic of Korea
| | - Nara Shin
- Department of Medical Science, Chungnam National University College of Medicine, Daejeon, Republic of Korea.,Department of Anatomy and Cell Biology, Brain Research Institute, Chungnam National University College of Medicine, Daejeon, 35015, Republic of Korea
| | - Hyo Jung Shin
- Department of Medical Science, Chungnam National University College of Medicine, Daejeon, Republic of Korea.,Department of Anatomy and Cell Biology, Brain Research Institute, Chungnam National University College of Medicine, Daejeon, 35015, Republic of Korea
| | - Jaewon Beom
- Department of Rehabilitation Medicine, Seoul National University Bundang Hospital, Seongnam, Gyeonggi-do, Republic of Korea
| | - Dong Woon Kim
- Department of Medical Science, Chungnam National University College of Medicine, Daejeon, Republic of Korea. .,Department of Anatomy and Cell Biology, Brain Research Institute, Chungnam National University College of Medicine, Daejeon, 35015, Republic of Korea.
| | - Jinhyun Kim
- Department of Internal Medicine, Chungnam National University College of Medicine, Daejeon, 35015, Republic of Korea.
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17
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Agthong S, Rodtayoy M, Roumwong A. Expression of autophagic and ubiquitin–proteasome proteins in the peripheral nervous system after nerve injury. ASIAN BIOMED 2020. [DOI: 10.1515/abm-2019-0057] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/15/2022]
Abstract
Abstract
Background
Autophagy and ubiquitin–proteasome (UPS) are two main degradation systems for intracellular proteins. They are essential for homeostasis of neurons during normal and pathological conditions, but their changes after nerve injury remain unclear.
Objective
To examine the protein expression of autophagy and UPS in the dorsal root ganglia (DRG), including intact and injured sciatic nerves after crush injury in rats.
Methods
Left sciatic nerve crush was done in all Wistar rats and the specimens were removed at 1, 3, 7, and 14 days after injury. Expression of the autophagic (Beclin-1 and p62) and UPS proteins [muscle ring finger-1 (MuRF1) and ubiquitinated proteins] was measured using Western blot analysis.
Results
Expression of p62 was significantly increased in the injured versus intact sciatic nerves on day 1 and day 7 (P < 0.05 and P < 0.01, respectively). There was a trend toward higher expression of Beclin-1 on the crushed nerve. In the DRG, expression of p62 and Beclin-1 was not significantly different between the two sides. Expression of MuRF1 and ubiquitinated proteins was not significantly different between the left and right DRG. The low quantity of MuRF1 and high variations in the ubiquitinated protein levels in the nerve prevented further analysis.
Conclusions
These results indicated the induction of autophagy with accumulation of autophagosomes in the nerve, but not DRG, after nerve injury. Future studies on the effects of the autophagic changes and the precise activity of UPS in nerve trauma are crucial.
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Affiliation(s)
- Sithiporn Agthong
- Department of Anatomy, Faculty of Medicine , Chulalongkorn University , Bangkok 10330 , Thailand
| | - Marisa Rodtayoy
- Department of Anatomy, Faculty of Medicine , Chulalongkorn University , Bangkok 10330 , Thailand
| | - Atitaya Roumwong
- Department of Anatomy, Faculty of Medicine , Chulalongkorn University , Bangkok 10330 , Thailand
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18
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CX3CR1-Targeted PLGA Nanoparticles Reduce Microglia Activation and Pain Behavior in Rats with Spinal Nerve Ligation. Int J Mol Sci 2020; 21:ijms21103469. [PMID: 32423102 PMCID: PMC7279022 DOI: 10.3390/ijms21103469] [Citation(s) in RCA: 14] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/23/2020] [Revised: 05/08/2020] [Accepted: 05/12/2020] [Indexed: 02/07/2023] Open
Abstract
Activation of CX3CR1 in microglia plays an important role in the development of neuropathic pain. Here, we investigated whether neuropathic pain could be attenuated in spinal nerve ligation (SNL)-induced rats by reducing microglial activation through the use of poly(D,L-lactic-co-glycolic acid) (PLGA)-encapsulated CX3CR1 small-interfering RNA (siRNA) nanoparticles. After confirming the efficacy and specificity of CX3CR1 siRNA, as evidenced by its anti-inflammatory effects in lipopolysaccharide-stimulated BV2 cells in vitro, PLGA-encapsulated CX3CR1 siRNA nanoparticles were synthesized by sonication using the conventional double emulsion (W/O/W) method and administered intrathecally into SNL rats. CX3CR1 siRNA-treated rats exhibited significant reductions in the activation of microglia in the spinal dorsal horn and a downregulation of proinflammatory mediators, as well as a significant attenuation of mechanical allodynia. These data indicate that the PLGA-encapsulated CX3CR1 siRNA nanoparticles effectively reduce neuropathic pain in SNL-induced rats by reducing microglial activity and the expression of proinflammatory mediators. Therefore, we believe that PLGA-encapsulated CX3CR1 siRNA nanoparticles represent a valuable new treatment option for neuropathic pain.
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Shin N, Shin HJ, Yi Y, Beom J, Lee W, Lee CH, Kim DW. p66shc siRNA-Encapsulated PLGA Nanoparticles Ameliorate Neuropathic Pain Following Spinal Nerve Ligation. Polymers (Basel) 2020; 12:polym12051014. [PMID: 32365512 PMCID: PMC7284875 DOI: 10.3390/polym12051014] [Citation(s) in RCA: 13] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/18/2020] [Revised: 04/17/2020] [Accepted: 04/22/2020] [Indexed: 12/17/2022] Open
Abstract
p66shc, a member of the shc adaptor protein family, has been shown to participate in regulation of mitochondrial homeostasis, apoptosis, and autophagosome formation. The present study was performed to investigate whether p66shc siRNA-encapsulated poly(d,l-lactic-co-glycolic acid) nanoparticles (p66shc siRNA-PLGA NPs) can attenuate spinal nerve ligation (SNL)-induced neuropathic pain in rats. The SNL-induced pain behavior was decreased in the p66shc siRNA-PLGA NP-treated group compared with the scrambled siRNA-PLGA NP-treated group. In the L5 spinal cord of the p66shc siRNA-PLGA NP-treated group, expression levels of phosphorylated p66shc, cleaved caspase-3, p62, and PINK1, as well as microglial activation, were also decreased. In addition, p66shc knockdown using p66shc siRNA reduced the expression levels of cleaved caspase-3, p62, and PINK1, as well as proinflammatory mediators in the H2O2-treated HT22 neuronal cells. These results suggest that downregulation of p66shc expression in the spinal cord using p66shc siRNA-PLGA NPs could reduce the SNL-induced neuropathic pain by attenuating the SNL-induced aberrant autophagic, mitophagic, and neuroinflammatory processes in rats.
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Affiliation(s)
- Nara Shin
- Department of Medical Science, Chungnam National University College of Medicine, Daejeon 35015, Korea
- Department of Anatomy, Brain Research Institute, Chungnam National University College of Medicine, Daejeon 35015, Korea
| | - Hyo Jung Shin
- Department of Medical Science, Chungnam National University College of Medicine, Daejeon 35015, Korea
- Department of Anatomy, Brain Research Institute, Chungnam National University College of Medicine, Daejeon 35015, Korea
| | - Yoonyoung Yi
- Department of Pediatrics, College of Medicine, Hallym University and Gangdong Sacred Heart Hospital, Seoul 05355, Korea
| | - Jaewon Beom
- Department of Rehabilitation Medicine, Seoul National University Bundang Hospital, Seongnam 13620, Korea
| | - Wonhyung Lee
- Department of Anesthesia and Pain Medicine, Chungnam National University Hospital, Daejeon 35015, Korea
| | - Choong-Hyun Lee
- Department of Pharmacy, College of Pharmacy, Dankook University, Cheonan 31116, Korea
- Correspondence: (C.-H.L.); (D.W.K.); Tel.: +82-41-550-1441 (C.-H.L.); +82-42-580-8201 (D.W.K.); Fax: +82-41-559-7899 (C.-H.L.); +82-42-586-4800 (D.W.K.)
| | - Dong Woon Kim
- Department of Medical Science, Chungnam National University College of Medicine, Daejeon 35015, Korea
- Department of Anatomy, Brain Research Institute, Chungnam National University College of Medicine, Daejeon 35015, Korea
- Correspondence: (C.-H.L.); (D.W.K.); Tel.: +82-41-550-1441 (C.-H.L.); +82-42-580-8201 (D.W.K.); Fax: +82-41-559-7899 (C.-H.L.); +82-42-586-4800 (D.W.K.)
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20
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Meng XL, Fu P, Wang L, Yang X, Hong G, Zhao X, Lao J. Increased EZH2 Levels in Anterior Cingulate Cortex Microglia Aggravate Neuropathic Pain by Inhibiting Autophagy Following Brachial Plexus Avulsion in Rats. Neurosci Bull 2020; 36:793-805. [PMID: 32346844 DOI: 10.1007/s12264-020-00502-w] [Citation(s) in RCA: 15] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/12/2019] [Accepted: 01/07/2020] [Indexed: 12/19/2022] Open
Abstract
After brachial plexus avulsion (BPA), microglia induce inflammation, initiating and maintaining neuropathic pain. EZH2 (enhancer of zeste homolog 2) has been implicated in inflammation and neuropathic pain, but the mechanisms by which it regulates neuropathic pain remain unclear. Here, we found that EZH2 levels were markedly upregulated during BPA-induced neuropathic pain in vivo and in vitro, stimulating pro-inflammatory cytokines (IL-1β, TNF-α, and IL-6) secretion in vivo. In rats with BPA-induced neuropathic pain, mechanical and cold hypersensitivities were induced by EZH2 upregulation and inhibited by EZH2 downregulation in the anterior cingulate cortex. Microglial autophagy was also significantly inhibited, with EZH2 inhibition activating autophagy and reducing neuroinflammation in vivo. However, this effect was impaired by inhibiting autophagy with 3-methyladenine, suggesting that the MTOR signaling pathway is a functional target of EZH2. These data suggest that EZH2 regulates neuroinflammation and neuropathic pain via a novel MTOR-mediated autophagy signaling pathway, providing a promising approach for managing neuropathic pain.
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Affiliation(s)
- Xiang-Lei Meng
- Department of Hand Surgery, Huashan Hospital, Fudan University, Shanghai, 200040, China
- Key Laboratory of Hand Reconstruction, Ministry of Health, Shanghai, 200032, China
- Shanghai Key Laboratory of Peripheral Nerve and Microsurgery, Shanghai, 200032, China
| | - Pengfei Fu
- Department of Neurosurgery, Huashan Hospital, Fudan University, Shanghai, 200040, China
| | - Lin Wang
- Health Management Center, The First Affiliated Hospital of Zhengzhou University, Zhengzhou, 450001, China
| | - Xun Yang
- Department of Hand Surgery, Huashan Hospital, Fudan University, Shanghai, 200040, China
- Key Laboratory of Hand Reconstruction, Ministry of Health, Shanghai, 200032, China
- Shanghai Key Laboratory of Peripheral Nerve and Microsurgery, Shanghai, 200032, China
| | - Guanghui Hong
- Department of Hand Surgery, Huashan Hospital, Fudan University, Shanghai, 200040, China
- Key Laboratory of Hand Reconstruction, Ministry of Health, Shanghai, 200032, China
- Shanghai Key Laboratory of Peripheral Nerve and Microsurgery, Shanghai, 200032, China
| | - Xin Zhao
- Department of Hand Surgery, Huashan Hospital, Fudan University, Shanghai, 200040, China
- Key Laboratory of Hand Reconstruction, Ministry of Health, Shanghai, 200032, China
- Shanghai Key Laboratory of Peripheral Nerve and Microsurgery, Shanghai, 200032, China
| | - Jie Lao
- Department of Hand Surgery, Huashan Hospital, Fudan University, Shanghai, 200040, China.
- Key Laboratory of Hand Reconstruction, Ministry of Health, Shanghai, 200032, China.
- Shanghai Key Laboratory of Peripheral Nerve and Microsurgery, Shanghai, 200032, China.
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21
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Phạm TL, Yin Y, Kwon HH, Shin N, Kim SI, Park H, Shin J, Shin HJ, Hwang JA, Song HJ, Kim SR, Lee JH, Hwang PTJ, Jun HW, Kim DW. miRNA 146a-5p-loaded poly(d,l-lactic-co-glycolic acid) nanoparticles impair pain behaviors by inhibiting multiple inflammatory pathways in microglia. Nanomedicine (Lond) 2020; 15:1113-1126. [PMID: 32292108 DOI: 10.2217/nnm-2019-0462] [Citation(s) in RCA: 15] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/23/2022] Open
Abstract
Aims: We investigated whether miRNA (miR) 146a-5p-loaded nanoparticles (NPs) can attenuate neuropathic pain behaviors in the rat spinal nerve ligation-induced neuropathic pain model by inhibiting activation of the NF-κB and p38 MAPK pathways in spinal microglia. Materials & methods: After NP preparation, miR NPs were assessed for their physical characteristics and then injected intrathecally into the spinal cords of rat spinal nerve ligation rats to test their analgesic effects. Results: miR NPs reduced pain behaviors for 11 days by negatively regulating the inflammatory response in spinal microglia. Conclusion: The anti-inflammatory effects of miR 146a-5p along with nanoparticle-based materials make miR NPs promising tools for treating neuropathic pain.
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Affiliation(s)
- Thuỳ Linh Phạm
- Department of Medical Science, Chungnam National University College of Medicine, Daejeon, 35015, Republic of Korea.,Department of Anatomy and Cell Biology, Brain Research Institute, Chungnam National University College of Medicine, Daejeon, 35015, Republic of Korea
| | - Yuhua Yin
- Department of Medical Science, Chungnam National University College of Medicine, Daejeon, 35015, Republic of Korea.,Department of Anatomy and Cell Biology, Brain Research Institute, Chungnam National University College of Medicine, Daejeon, 35015, Republic of Korea.,Department of Anesthesia, Guangzhou Women and Children's Medical Center, Guangzhou, 510623, Guangdong Province, PR China
| | - Hyeok Hee Kwon
- Department of Medical Science, Chungnam National University College of Medicine, Daejeon, 35015, Republic of Korea.,Department of Anatomy and Cell Biology, Brain Research Institute, Chungnam National University College of Medicine, Daejeon, 35015, Republic of Korea
| | - Nara Shin
- Department of Medical Science, Chungnam National University College of Medicine, Daejeon, 35015, Republic of Korea.,Department of Anatomy and Cell Biology, Brain Research Institute, Chungnam National University College of Medicine, Daejeon, 35015, Republic of Korea
| | - Song I Kim
- Department of Medical Science, Chungnam National University College of Medicine, Daejeon, 35015, Republic of Korea.,Department of Anatomy and Cell Biology, Brain Research Institute, Chungnam National University College of Medicine, Daejeon, 35015, Republic of Korea
| | - Hyewon Park
- Department of Medical Science, Chungnam National University College of Medicine, Daejeon, 35015, Republic of Korea.,Department of Anatomy and Cell Biology, Brain Research Institute, Chungnam National University College of Medicine, Daejeon, 35015, Republic of Korea
| | - Juhee Shin
- Department of Medical Science, Chungnam National University College of Medicine, Daejeon, 35015, Republic of Korea.,Department of Anatomy and Cell Biology, Brain Research Institute, Chungnam National University College of Medicine, Daejeon, 35015, Republic of Korea
| | - Hyo Jung Shin
- Department of Medical Science, Chungnam National University College of Medicine, Daejeon, 35015, Republic of Korea.,Department of Anatomy and Cell Biology, Brain Research Institute, Chungnam National University College of Medicine, Daejeon, 35015, Republic of Korea
| | - Jeong-Ah Hwang
- Department of Medical Science, Chungnam National University College of Medicine, Daejeon, 35015, Republic of Korea.,Department of Anatomy and Cell Biology, Brain Research Institute, Chungnam National University College of Medicine, Daejeon, 35015, Republic of Korea
| | - Hee-Jung Song
- Department of Neurology, Brain Research Institute, Chungnam National University College of Medicine, Daejeon, 35015, Republic of Korea
| | - Sang Ryong Kim
- School of Life Sciences, BK21 Plus KNU Creative BioResearch Group, Institute of Life Science & Biotechnology, Brain Science & Engineering Institute, Kyungpook National University, Daegu, 41566, Republic of Korea
| | - Joo Hyoung Lee
- Department of Pathology, University of Alabama at Birmingham, Birmingham, AL 35294, USA
| | - Patrick T J Hwang
- Department of Biomedical Engineering, University of Alabama at Birmingham, Birmingham, AL 35294, USA
| | - Ho-Wook Jun
- Department of Biomedical Engineering, University of Alabama at Birmingham, Birmingham, AL 35294, USA
| | - Dong Woon Kim
- Department of Medical Science, Chungnam National University College of Medicine, Daejeon, 35015, Republic of Korea.,Department of Anatomy and Cell Biology, Brain Research Institute, Chungnam National University College of Medicine, Daejeon, 35015, Republic of Korea
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22
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Romeo-Guitart D, Casas C. NeuroHeal Treatment Alleviates Neuropathic Pain and Enhances Sensory Axon Regeneration. Cells 2020; 9:E808. [PMID: 32230770 PMCID: PMC7226810 DOI: 10.3390/cells9040808] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/11/2020] [Revised: 03/16/2020] [Accepted: 03/24/2020] [Indexed: 01/06/2023] Open
Abstract
Peripheral nerve injury (PNI) leads to the loss of motor, sensory, and autonomic functions, and often triggers neuropathic pain. During the last years, many efforts have focused on finding new therapies to increase axonal regeneration or to alleviate painful conditions. Still only a few of them have targeted both phenomena. Incipient or aberrant sensory axon regeneration is related to abnormal unpleasant sensations, such as hyperalgesia or allodynia. We recently have discovered NeuroHeal, a combination of two repurposed drugs; Acamprosate and Ribavirin. NeuroHeal is a neuroprotective agent that also enhances motor axon regeneration after PNI. In this work, we investigated its effect on sensory fiber regeneration and PNI-induced painful sensations in a rat model of spare nerve injury and nerve crush. The follow up of the animals showed that NeuroHeal treatment reduced the signs of neuropathic pain in both models. Besides, the treatment favored sensory axon regeneration, as observed in dorsal root ganglion explants. Mechanistically, the effects observed in vivo may improve the resolution of cell-protective autophagy. Additionally, NeuroHeal treatment modulated the P2X4-BDNF-KCC2 axis, which is an essential driver of neuropathic pain. These data open a new therapeutic avenue based on autophagic modulation to foster endogenous regenerative mechanisms and reduce the appearance of neuropathic pain in PNI.
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Affiliation(s)
- David Romeo-Guitart
- Institut de Neurociències (INc) and Department of Cell Biology, Physiology and Immunology, Universitat Autònoma de Barcelona (UAB), 08193 Bellaterra, Barcelona, Spain;
- Institut Necker Enfants-Malades (INEM), INSERM U1151, Laboratory “Hormonal regulation of brain development and functions”—Team 8, Université Paris Descartes, Sorbonne Paris Cité, 75015 Paris, France
| | - Caty Casas
- Institut de Neurociències (INc) and Department of Cell Biology, Physiology and Immunology, Universitat Autònoma de Barcelona (UAB), 08193 Bellaterra, Barcelona, Spain;
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23
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Yin Y, Hong J, Phạm TL, Shin J, Gwon DH, Kwon HH, Shin N, Shin HJ, Lee SY, Lee WH, Kim DW. Evans Blue Reduces Neuropathic Pain Behavior by Inhibiting Spinal ATP Release. Int J Mol Sci 2019; 20:ijms20184443. [PMID: 31505901 PMCID: PMC6770806 DOI: 10.3390/ijms20184443] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/23/2019] [Revised: 08/19/2019] [Accepted: 09/05/2019] [Indexed: 12/21/2022] Open
Abstract
Upon peripheral nerve injury, vesicular ATP is released from damaged primary afferent neurons. This extracellular ATP subsequently activates purinergic receptors of the spinal cord, which play a critical role in neuropathic pain. As an inhibitor of the vesicular nucleotide transporter (VNUT), Evans blue (EB) inhibits the vesicular storage and release of ATP in neurons. Thus, we tested whether EB could attenuate neuropathic pain behavior induced by spinal nerve ligation (SNL) in rats by targeting VNUT. An intrathecal injection of EB efficiently attenuated mechanical allodynia for five days in a dose-dependent manner and enhanced locomotive activity in an SNL rat model. Immunohistochemical analysis showed that EB was found in VNUT immunoreactivity on neurons in the dorsal root ganglion and the spinal dorsal horn. The level of ATP in cerebrospinal fluid in rats with SNL-induced neuropathic pain decreased upon administration of EB. Interestingly, EB blocked ATP release from neurons, but not glial cells in vitro. Eventually, the loss of ATP decreased microglial activity in the ipsilateral dorsal horn of the spinal cord, followed by a reduction in reactive oxygen species and proinflammatory mediators, such as interleukin (IL)-1β and IL-6. Finally, a similar analgesic effect of EB was demonstrated in rats with monoiodoacetate-induced osteoarthritis (OA) pain. Taken together, these data demonstrate that EB prevents ATP release in the spinal dorsal horn and reduces the ATP/purinergic receptor-induced activation of spinal microglia followed by a decline in algogenic substances, thereby relieving neuropathic pain in rats with SNL.
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Affiliation(s)
- Yuhua Yin
- Department of Medical Science, Chungnam National University School of Medicine, Daejeon 35015, Korea.
- Department of Anesthesiology and Pain Medicine, Chungnam National University Hospital, Daejeon 35015, Korea.
| | - Jinpyo Hong
- Department of Anatomy, Brain Research Institute, Chungnam National University School of Medicine, Daejeon 35015, Korea.
| | - Thuỳ Linh Phạm
- Department of Medical Science, Chungnam National University School of Medicine, Daejeon 35015, Korea.
| | - Juhee Shin
- Department of Medical Science, Chungnam National University School of Medicine, Daejeon 35015, Korea.
| | - Do Hyeong Gwon
- Department of Medical Science, Chungnam National University School of Medicine, Daejeon 35015, Korea.
| | - Hyeok Hee Kwon
- Department of Medical Science, Chungnam National University School of Medicine, Daejeon 35015, Korea.
| | - Nara Shin
- Department of Medical Science, Chungnam National University School of Medicine, Daejeon 35015, Korea.
| | - Hyo Jung Shin
- Department of Medical Science, Chungnam National University School of Medicine, Daejeon 35015, Korea.
| | - Sun Yeul Lee
- Department of Anesthesiology and Pain Medicine, Chungnam National University Hospital, Daejeon 35015, Korea.
| | - Won-Hyung Lee
- Department of Anesthesiology and Pain Medicine, Chungnam National University Hospital, Daejeon 35015, Korea.
| | - Dong Woon Kim
- Department of Medical Science, Chungnam National University School of Medicine, Daejeon 35015, Korea.
- Department of Anatomy, Brain Research Institute, Chungnam National University School of Medicine, Daejeon 35015, Korea.
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24
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Wu J, Lipinski MM. Autophagy in Neurotrauma: Good, Bad, or Dysregulated. Cells 2019; 8:E693. [PMID: 31295858 PMCID: PMC6678153 DOI: 10.3390/cells8070693] [Citation(s) in RCA: 73] [Impact Index Per Article: 14.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/31/2019] [Revised: 07/06/2019] [Accepted: 07/09/2019] [Indexed: 12/12/2022] Open
Abstract
Autophagy is a physiological process that helps maintain a balance between the manufacture of cellular components and breakdown of damaged organelles and other toxic cellular constituents. Changes in autophagic markers are readily detectable in the spinal cord and brain following neurotrauma, including traumatic spinal cord and brain injury (SCI/TBI). However, the role of autophagy in neurotrauma remains less clear. Whether autophagy is good or bad is under debate, with strong support for both a beneficial and detrimental role for autophagy in experimental models of neurotrauma. Emerging data suggest that autophagic flux, a measure of autophagic degradation activity, is impaired in injured central nervous systems (CNS), and interventions that stimulate autophagic flux may provide neuroprotection in SCI/TBI models. Recent data demonstrating that neurotrauma can cause lysosomal membrane damage resulting in pathological autophagosome accumulation in the spinal cord and brain further supports the idea that the impairment of the autophagy-lysosome pathway may be a part of secondary injury processes of SCI/TBI. Here, we review experimental work on the complex and varied responses of autophagy in terms of both the beneficial and detrimental effects in SCI and TBI models. We also discuss the existing and developing therapeutic options aimed at reducing the disruption of autophagy to protect the CNS after injuries.
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Affiliation(s)
- Junfang Wu
- Department of Anesthesiology and Center for Shock, Trauma and Anesthesiology Research (STAR), University of Maryland School of Medicine, Baltimore, MD 21201, USA.
- Department of Anatomy and Neurobiology, University of Maryland School of Medicine, Baltimore, MD 21201, USA.
- Center to Advance Chronic Pain Research, University of Maryland, Baltimore, MD 21201, USA.
| | - Marta M Lipinski
- Department of Anesthesiology and Center for Shock, Trauma and Anesthesiology Research (STAR), University of Maryland School of Medicine, Baltimore, MD 21201, USA
- Department of Anatomy and Neurobiology, University of Maryland School of Medicine, Baltimore, MD 21201, USA
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25
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Yin Y, Park H, Lee SY, Lee WH, Song HJ, Kim J, Kim DW, Hong J. Analgesic Effect of Toll-like Receptor 4 Antagonistic Peptide 2 on Mechanical Allodynia Induced with Spinal Nerve Ligation in Rats. Exp Neurobiol 2019; 28:352-361. [PMID: 31308795 PMCID: PMC6614064 DOI: 10.5607/en.2019.28.3.352] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/31/2019] [Revised: 05/11/2019] [Accepted: 05/28/2019] [Indexed: 01/06/2023] Open
Abstract
Neuroinflammation is one of the key mechanisms of neuropathic pain, which is primarily mediated by the Toll-like receptor 4 (TLR4) signaling pathways in microglia. Therefore, TLR4 may be a reasonable target for treatment of neuropathic pain. Here, we examined the analgesic effect of TLR4 antagonistic peptide 2 (TAP2) on neuropathic pain induced by spinal nerve ligation in rats. When lipopolysaccharide (LPS)-stimulated BV2 microglia cells were treated with TAP2 (10 µM), the mRNA levels of proinflammatory mediators, such as tumor necrosis factor (TNF)-α, interleukin (IL)-1β, IL-6, cyclooxygenase (COX)-2, and inducible nitric oxide synthase (iNOS), were markedly decreased by 54-83% as determined by quantitative PCR (qPCR) analysis. Furthermore, when TAP2 (25 nmol in 20 µL PBS) was intrathecally administered to the spinal nerve ligation-induced rats on day 3 after surgery, the mechanical allodynia was markedly decreased for approximately 2 weeks in von Frey filament tests, with a reduction in microglial activation. On immunohistochemical and qPCR analyses, both the level of reactive oxygen species and the gene expression of the proinflammatory mediators, such as TNF-α, IL-1β, IL-6, COX-2, and iNOS, were significantly decreased in the ipsilateral spinal dorsal horn. Finally, the analgesic effect of TAP2 was reproduced in rats with monoiodoacetate-induced osteoarthritic pain. The findings of the present study suggest that TAP2 efficiently mitigates neuropathic pain behavior by suppressing microglial activation, followed by downregulation of neuropathic pain-related factors, such as reactive oxygen species and proinflammatory molecules. Therefore, it may be useful as a new analgesic for treatment of neuropathic pain.
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Affiliation(s)
- Yuhua Yin
- Department of Medical Science, Chungnam National University School of Medicine, Daejeon 35015, Korea.,Department of Anatomy, Brain Research Institute, Chungnam National University School of Medicine, Daejeon 35015, Korea
| | - Hyewon Park
- Department of Medical Science, Chungnam National University School of Medicine, Daejeon 35015, Korea.,Department of Anatomy, Brain Research Institute, Chungnam National University School of Medicine, Daejeon 35015, Korea
| | - Sun Yeul Lee
- Department of Anesthesia and Pain Medicine, Chungnam National University Hospital, Daejeon 35015, Korea
| | - Won-Hyung Lee
- Department of Anesthesia and Pain Medicine, Chungnam National University Hospital, Daejeon 35015, Korea
| | - Hee-Jung Song
- Department of Neurology, Chungnam National University Hospital, Daejeon 35015, Korea
| | - Jinhyun Kim
- Department of Anesthesia and Pain Medicine, Chungnam National University Hospital, Daejeon 35015, Korea
| | - Dong Woon Kim
- Department of Medical Science, Chungnam National University School of Medicine, Daejeon 35015, Korea.,Department of Anatomy, Brain Research Institute, Chungnam National University School of Medicine, Daejeon 35015, Korea
| | - Jinpyo Hong
- Department of Anatomy, Brain Research Institute, Chungnam National University School of Medicine, Daejeon 35015, Korea
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26
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Liu X, Zhu M, Ju Y, Li A, Sun X. Autophagy dysfunction in neuropathic pain. Neuropeptides 2019; 75:41-48. [PMID: 30910234 DOI: 10.1016/j.npep.2019.03.005] [Citation(s) in RCA: 24] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 10/31/2018] [Revised: 02/28/2019] [Accepted: 03/18/2019] [Indexed: 01/13/2023]
Abstract
Autophagy is a lysosomal degradation pathway that maintains tissue homeostasis by recycling damaged and aged cellular components, which plays important roles in development of the nervous system, as well as in neuronal function and survival. In addition, autophagy dysfunction underlies neuropathic pain. Thus, the modulation of autophagy can alleviate neuropathic pain. Here, we describe the definition, mechanisms of autophagy and neuropathic pain. On this basis, we further discuss the role of autophagy dysfunction in neuropathic pain. This review updates our knowledge on autophagy mechanisms which propose potential therapeutic targets for the treatment of neuropathic pain.
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Affiliation(s)
- Xiaojuan Liu
- Department of Pathogen Biology, Medical College, Nantong University, Nantong 226001, Jiangsu, China
| | - Manhui Zhu
- Department of Ophthalmology, Affiliated Lixiang Eye Hospital of Soochow University, Suzhou 210005, Jiangsu, China
| | - Yuanyuan Ju
- Medical College, Nantong University, Nantong 2266001, Jiangsu, China
| | - Aihong Li
- Department of Neurology, Affiliated Hospital of Nantong University, Nantong 226001, Jiangsu, China.
| | - Xiaolei Sun
- Department of Pathogen Biology, Medical College, Nantong University, Nantong 226001, Jiangsu, China.
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27
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Shin J, Yin Y, Kim DK, Lee SY, Lee W, Kang JW, Kim DW, Hong J. Foxp3 plasmid-encapsulated PLGA nanoparticles attenuate pain behavior in rats with spinal nerve ligation. NANOMEDICINE-NANOTECHNOLOGY BIOLOGY AND MEDICINE 2019; 18:90-100. [DOI: 10.1016/j.nano.2019.02.023] [Citation(s) in RCA: 21] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/04/2019] [Revised: 02/11/2019] [Accepted: 02/24/2019] [Indexed: 11/29/2022]
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28
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Yi MH, Shin J, Shin N, Yin Y, Lee SY, Kim CS, Kim SR, Zhang E, Kim DW. PINK1 mediates spinal cord mitophagy in neuropathic pain. J Pain Res 2019; 12:1685-1699. [PMID: 31239755 PMCID: PMC6554001 DOI: 10.2147/jpr.s198730] [Citation(s) in RCA: 15] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/18/2018] [Accepted: 04/24/2019] [Indexed: 01/13/2023] Open
Abstract
Background: Mitophagy is the selective engulfment of mitochondria by autophagosomes and the subsequent mitochondrial catabolism by lysosomes. Evidence has suggested an important role for mitochondrial dynamics and mitophagic flux in the development of many different neurodegenerative diseases. Objectives: The potential role of the mechanism underlying mitochondrial dynamics and mitophagic flux as it may relate to neuropathic pain is not well understood. This is a disease that largely remains an area of mechanistic uncertainty. PINK1 is a PTEN-induced mitochondrial kinase that can be selectively activated under mitochondrial stress conditions and lead to the induction of mitophagy. Materials and methods: A neuropathic pain rat model was established via spinal nerve ligation (SNL) and nociception was assayed via the von Frey filament method. Increased expression of PINK1 and the mechanism of mitophagy was detected in GABAergic interneurons of dorsal horn neurons of mice that underwent L5 SNL in comparison to control mice counterparts (n=8, P<0.001) by Western blotting, immunohistochemistry and double immunofluorescence staining. Results: Elevated expression of PINK1 appeared to localize selectively to GABAergic interneurons, particularly within autophagic mitochondria as evidenced by co-localization studies of PINK1 with BECN1, LC3II and COX IV on immunofluorescent microscopy. Furthermore, we also detected a significant increase in autophagosomes in dorsal horn neurons of SNL mice and this was consistent with increased autophagic activity as measured by the p62 autophagic substrate. Conclusion: These results demonstrate that neuropathic pain causes aberrant mitophagic flux selectively in GABAergic interneurons and provide evidence implicating mitophagy as an important area of future molecular studies to enhance our understanding of neuropathic pain.
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Affiliation(s)
- Min-Hee Yi
- Department of Neurology, Mayo Clinic, Rochester, MN 55905, USA
| | - Juhee Shin
- Department of Anatomy, Brain Research Institute, Chungnam National University School of Medicine, Daejeon 301-747, Republic of Korea.,Department of Medical Science, Chungnam National University School of Medicine, Daejeon 301-747, Republic of Korea
| | - Nara Shin
- Department of Anatomy, Brain Research Institute, Chungnam National University School of Medicine, Daejeon 301-747, Republic of Korea.,Department of Medical Science, Chungnam National University School of Medicine, Daejeon 301-747, Republic of Korea
| | - Yuhua Yin
- Department of Anatomy, Brain Research Institute, Chungnam National University School of Medicine, Daejeon 301-747, Republic of Korea.,Department of Anesthesiology and Pain Medicine, Chungnam National University Hospital, Daejeon 301-747, South Korea
| | - Sun Yeul Lee
- Department of Anesthesiology and Pain Medicine, Chungnam National University Hospital, Daejeon 301-747, South Korea
| | - Cuk-Seong Kim
- Department of Medical Science, Chungnam National University School of Medicine, Daejeon 301-747, Republic of Korea.,Department of Physiology, Chungnam National University School of Medicine, Daejeon 301-747, Republic of Korea
| | - Sang Ryong Kim
- School of Life Sciences, BK21 Plus KNU Creative BioResearch Group, Institute of Life Science & Biotechnology, Brain Science and Engineering Institute, Kyungpook National University, Daegu 41566, Republic of Korea
| | - Enji Zhang
- Department of Anesthesia Medicine, Yanbian University Hospital, Yanbian 133000, People's Republic of China
| | - Dong Woon Kim
- Department of Anatomy, Brain Research Institute, Chungnam National University School of Medicine, Daejeon 301-747, Republic of Korea.,Department of Medical Science, Chungnam National University School of Medicine, Daejeon 301-747, Republic of Korea
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29
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Liu YD, Wang ZB, Han G, Jin L, Zhao P. Hyperbaric oxygen relieves neuropathic pain through AKT/TSC2/mTOR pathway activity to induce autophagy. J Pain Res 2019; 12:443-451. [PMID: 30774414 PMCID: PMC6361320 DOI: 10.2147/jpr.s189353] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/03/2023] Open
Abstract
Background Our previous study suggested that HBO treatment attenuated neuropathic pain by inhibiting mTOR to induce autophagy in SNL neuropathic pain model. The aim of this study was to evaluate the role of AKT/TSC2/mTOR pathway in SNL and autophagy and determine whether HBO treatment could relieve neuropathic pain via modulating AKT/TSC2/mTOR pathway. Materials and methods Rats were randomly divided into sham, SNL, SNL + HBO treatment, SNL + vehicle, and SNL + AKT inhibitor groups. Neuropathic pain was induced following SNL procedure. Rats in the SNL + HBO group received HBO treatment for 7 consecutive days beginning on postoperative day 1. The SNL + vehicle group received 10 µL of 3% dimethyl sulfoxide in saline. SNL + AKT inhibitor group received 10 µL AKT inhibitor IV intrathecally. Mechanical withdrawal threshold tests were performed to evaluate mechanical hypersensitivity. AKT, p-AKT, TSC2, mTOR, p-mTOR, and LC3-II protein expressions were examined by Western blot analysis. Results HBO reversed AKT/TSC2/mTOR upregulation induced by SNL and attenuated neuropathic pain. Intrathecal injection of AKT inhibitor IV decreased the activity of AKT/TSC2/mTOR pathway and increased LC3-II expression accompanied by analgesic effect in SNL rats. Conclusion Taken together, our findings demonstrated AKT/TSC2/mTOR pathway was activated in SNL-induced neuropathic pain, and HBO treatment attenuated neuropathic pain via neutralizing AKT/TSC2/mTOR pathway activation.
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Affiliation(s)
- Yong-Da Liu
- Department of Anesthesiology and Pain Management, Shengjing Hospital of China Medical University, Shenyang 110004, China,
| | - Zhi-Bin Wang
- Department of Anesthesiology and Pain Management, Shengjing Hospital of China Medical University, Shenyang 110004, China,
| | - Guang Han
- Department of Anesthesiology and Pain Management, Shengjing Hospital of China Medical University, Shenyang 110004, China,
| | - Li Jin
- Department of Orthopaedic Surgery, University of Virginia, Charlottesville, VA 22908, USA
| | - Ping Zhao
- Department of Anesthesiology and Pain Management, Shengjing Hospital of China Medical University, Shenyang 110004, China,
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30
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Feng XL, Deng HB, Wang ZG, Wu Y, Ke JJ, Feng XB. Suberoylanilide Hydroxamic Acid Triggers Autophagy by Influencing the mTOR Pathway in the Spinal Dorsal Horn in a Rat Neuropathic Pain Model. Neurochem Res 2018; 44:450-464. [PMID: 30560396 DOI: 10.1007/s11064-018-2698-1] [Citation(s) in RCA: 15] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/28/2018] [Revised: 11/05/2018] [Accepted: 12/10/2018] [Indexed: 02/08/2023]
Abstract
Histone acetylation levels can be upregulated by treating cells with histone deacetylase inhibitors (HDACIs), which can induce autophagy. Autophagy flux in the spinal cord of rats following the left fifth lumber spinal nerve ligation (SNL) is involved in the progression of neuropathic pain. Suberoylanilide hydroxamic acid (SAHA), one of the HDACIs can interfere with the epigenetic process of histone acetylation, which has been shown to ease neuropathic pain. Recent research suggest that SAHA can stimulate autophagy via the mammalian target of rapamycin (mTOR) pathway in some types of cancer cells. However, little is known about the role of SAHA and autophagy in neuropathic pain after nerve injury. In the present study, we aim to investigate autophagy flux and the role of the mTOR pathway on spinal cells autophagy activation in neuropathic pain induced by SNL in rats that received SAHA treatment. Autophagy-related proteins and mTOR or its active form were assessed by using western blot, immunohistochemistry, double immunofluorescence staining and transmission electron microscopy (TEM). We found that SAHA decreased the paw mechanical withdrawal threshold (PMWT) of the lower compared with SNL. Autophagy flux was mainly disrupted in the astrocytes and neuronal cells of the spinal cord dorsal horn on postsurgical day 28 and was reversed by daily intrathecal injection of SAHA (n = 100 nmol/day or n = 200 nmol/day). SAHA also decreased mTOR and phosphorylated mTOR (p-mTOR) expression, especially p-mTOR expression in astrocytes and neuronal cells of the spinal dorsal horn. These results suggest that SAHA attenuates neuropathic pain and contributes to autophagy flux in astrocytes and neuronal cells of the spinal dorsal horn via the mTOR signaling pathway.
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Affiliation(s)
- Xiang-Lan Feng
- Department of Anesthesiology, Zhongnan Hospital of Wuhan University, No. 169 Donghu Rd, Wuhan, 430071, Hubei, China
| | - Hong-Bo Deng
- Department of Anesthesiology, Zhongnan Hospital of Wuhan University, No. 169 Donghu Rd, Wuhan, 430071, Hubei, China
| | - Zheng-Gang Wang
- Department of Anesthesiology, Zhongnan Hospital of Wuhan University, No. 169 Donghu Rd, Wuhan, 430071, Hubei, China
| | - Yun Wu
- Department of Anesthesiology, Zhongnan Hospital of Wuhan University, No. 169 Donghu Rd, Wuhan, 430071, Hubei, China
| | - Jian-Juan Ke
- Department of Anesthesiology, Zhongnan Hospital of Wuhan University, No. 169 Donghu Rd, Wuhan, 430071, Hubei, China
| | - Xiao-Bo Feng
- Department of Anesthesiology, Zhongnan Hospital of Wuhan University, No. 169 Donghu Rd, Wuhan, 430071, Hubei, China.
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31
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Weng W, Yao C, Poonit K, Zhou X, Sun C, Zhang F, Yan H. Metformin relieves neuropathic pain after spinal nerve ligation via autophagy flux stimulation. J Cell Mol Med 2018; 23:1313-1324. [PMID: 30451370 PMCID: PMC6349176 DOI: 10.1111/jcmm.14033] [Citation(s) in RCA: 30] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/02/2017] [Revised: 10/07/2018] [Accepted: 10/26/2018] [Indexed: 12/15/2022] Open
Abstract
Neuropathic pain is a well‐known type of chronic pain caused by damage to the nervous system. Autophagy is involved in the development and/or progression of many diseases, including neuropathic pain. Emerging evidence suggests that metformin relieves neuropathic pain in several neuropathic pain models; however, metformin's cellular and molecular mechanism for pain relief remains unknown. In this study, we investigated the therapeutic effects of metformin on pain relief after spinal nerve ligation (SNL) and its underlying mechanism of autophagy regulation. Behavioural analysis, histological assessment, expression of c‐Fos and molecular biological changes, as well as ultrastructural features, were investigated. Our findings showed that the number of autophagosomes and expression of autophagy markers, such as LC3 and beclin1, were increased, while the autophagy substrate protein p62, as well as the ubiquitinated proteins, were accumulated in the ipsilateral spinal cord. However, metformin enhanced the expression of autophagy markers, while it abrogated the abundance of p62 and ubiquitinated proteins. Blockage of autophagy flux by chloroquine partially abolished the apoptosis inhibition and analgesic effects of metformin on SNL. Taken together, these results illustrated that metformin relieved neuropathic pain through autophagy flux stimulation and provided a new direction for metformin drug development to treat neuropathic pain.
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Affiliation(s)
- Weidong Weng
- Department of Orthopedics, Division of Plastic and Hand Surgery, The Second Affiliated Hospital and Yuying Children's Hospital of Wenzhou Medical University, Wenzhou, China
| | - Chenglun Yao
- Department of Orthopedics, Division of Plastic and Hand Surgery, The Second Affiliated Hospital and Yuying Children's Hospital of Wenzhou Medical University, Wenzhou, China
| | - Keshav Poonit
- Department of Orthopedics, Division of Plastic and Hand Surgery, The Second Affiliated Hospital and Yuying Children's Hospital of Wenzhou Medical University, Wenzhou, China
| | - Xijie Zhou
- Department of Orthopedics, Division of Plastic and Hand Surgery, The Second Affiliated Hospital and Yuying Children's Hospital of Wenzhou Medical University, Wenzhou, China
| | - Chao Sun
- Department of Orthopedics, Division of Plastic and Hand Surgery, The Second Affiliated Hospital and Yuying Children's Hospital of Wenzhou Medical University, Wenzhou, China
| | - Feng Zhang
- Joseph M. Still Burn and Reconstructive Center, Jackson, Mississippi
| | - Hede Yan
- Department of Orthopedics, Division of Plastic and Hand Surgery, The Second Affiliated Hospital and Yuying Children's Hospital of Wenzhou Medical University, Wenzhou, China
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Impaired Autophagy of GABAergic Interneurons in Neuropathic Pain. Pain Res Manag 2018; 2018:9185368. [PMID: 30356379 PMCID: PMC6176324 DOI: 10.1155/2018/9185368] [Citation(s) in RCA: 24] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/20/2018] [Accepted: 09/12/2018] [Indexed: 12/30/2022]
Abstract
Neuropathic pain (NP) is caused by lesions of the peripheral fibers and central neurons in the somatosensory nervous system and affects 7-10% of the general population. Although the distinct cause of neuropathic pain has been investigated in primary afferent neurons over the years, pain modulation by central sensitization remains controversial. NP is believed to be driven by cell type-specific spinal synaptic plasticity in the dorsal horn. Upon intense afferent stimulation, spinothalamic tract neurons are potentiated, whereas GABAergic interneurons are inhibited leading to long-term depression. Growing evidences suggest that the inhibition of GABAergic neurons plays pivotal roles in the manifestation of neuropathic and inflammatory pain states. Downregulation of GABA transmission and impairment of GABAergic interneurons in the dorsal horn are critical consequences after spinal cord and peripheral nerve injuries. These impairments in GABAergic interneurons may be associated with dysfunctional autophagy, resulting in neuropathic pain. Here, we review an emerging number of investigations that suggest a pivotal role of impaired autophagy of GABAergic interneurons in NP. We discuss relevant research spurring the development of new targets and therapeutic agents of NP and emphasize the need for a multidisciplinary approach to manage NP in the future.
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Oh SH, Yoon MH, Lim KJ, Yu BS, Jee IG, Jung KT. Nefopam downregulates autophagy and c-Jun N-terminal kinase activity in the regulation of neuropathic pain development following spinal nerve ligation. BMC Anesthesiol 2018; 18:97. [PMID: 30053799 PMCID: PMC6064146 DOI: 10.1186/s12871-018-0559-8] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/22/2018] [Accepted: 07/13/2018] [Indexed: 02/03/2023] Open
Abstract
Background Neurodegeneration is associated with changes in basal cellular function due to the dysregulation of autophagy. A recent study introduced the involvement of autophagy during spinal nerve ligation (SNL). Nefopam has shown potential for reducing neuropathic pain, but the underlying mechanisms are unknown. Here, we investigated the effects of nefopam on neuropathic pain development following SNL, focusing on the involvement of autophagy. Methods The functional role of nefopam in capsaicin-induced autophagy was assessed by human glioblastoma M059 K cells. The neuropathic pain model was used to determine whether the effect of nefopam on pain control was mediated through autophagy control. Neuropathic pain was induced by L5 and L6 SNL in male rats randomized into three groups: Group S (sham-operated), Group C (received normal saline), and Group E (received nefopam). A behavioral test using a von Frey was examined. Expression changes of autophagy in response to nefopam was analyzed in spinal cord tissues (L4-L6) by immunoblotting and immunohistochemistry. Results The paw withdrawal threshold examined on days 3, 5, 7, and 14 post-SNL was significantly higher in Group E than in Group C. SNL increased the levels of microtubule-associated protein 1 light chain 3B (LC3B-1), with concomitant reduction of sequestosome 1 (SQTSM1/p62), compared with Group S, indicating that SNL induced autophagy. These effects were reversed by nefopam injection, and the results were confirmed by immunohistochemistry for LC3-I/II. Furthermore, SNL-mediated JNK activation was markedly decreased following nefopam injection. Hematoxylin and eosin staining on Day 14 post-SNL revealed that SNL caused lymphocyte infiltration and oligodendrocyte localization in the substantia gelatinosa of the dorsal gray horn, which were reduced by nefopam injection. Conclusion Collectively, the mode of action of nefopam on neuropathic pain appears to be associated with downregulation of phospho-JNK and autophagy, as well as modulation of the immune response.
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Affiliation(s)
- Seon-Hee Oh
- School of Medicine, Chosun University, 309 Pilmundaero, Dong-gu, Gwangju, 501-759, South Korea
| | - Myung Ha Yoon
- Department of Anesthesiology and Pain Medicine, Medical School, Chonnam National University, 42 Jebongro, Donggu, Gwangju, 501-757, South Korea
| | - Kyung Joon Lim
- Department of Anesthesiology and Pain Medicine, School of Medicine, Chosun University, Chosun University Hospital, 365 Pilmun-daero, Dong-gu, Gwangju, 61453, South Korea
| | - Byung Sik Yu
- Department of Anesthesiology and Pain Medicine, School of Medicine, Chosun University, Chosun University Hospital, 365 Pilmun-daero, Dong-gu, Gwangju, 61453, South Korea
| | - In Gook Jee
- Department of Anesthesiology and Pain Medicine, Chosun University Hospital, 365 Pilmun-daero, Dong-gu, Gwangju, 61453, South Korea
| | - Ki Tae Jung
- Department of Anesthesiology and Pain Medicine, School of Medicine, Chosun University, Chosun University Hospital, 365 Pilmun-daero, Dong-gu, Gwangju, 61453, South Korea.
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Muñoz-Galdeano T, Reigada D, Del Águila Á, Velez I, Caballero-López MJ, Maza RM, Nieto-Díaz M. Cell Specific Changes of Autophagy in a Mouse Model of Contusive Spinal Cord Injury. Front Cell Neurosci 2018; 12:164. [PMID: 29946241 PMCID: PMC6005838 DOI: 10.3389/fncel.2018.00164] [Citation(s) in RCA: 23] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/25/2018] [Accepted: 05/28/2018] [Indexed: 12/15/2022] Open
Abstract
Autophagy is an essential process of cellular waist clearance that becomes altered following spinal cord injury (SCI). Details on these changes, including timing after injury, underlying mechanisms, and affected cells, remain controversial. Here we present a characterization of autophagy in the mice spinal cord before and after a contusive SCI. In the undamaged spinal cord, analysis of LC3 and Beclin 1 autophagic markers reveals important differences in basal autophagy between neurons, oligodendrocytes, and astrocytes and even within cell populations. Following moderate contusion, western blot analyses of LC3 indicates that autophagy increases to a maximum at 7 days post injury (dpi), whereas unaltered Beclin 1 expression and increase of p62 suggests a possible blockage of autophagosome clearance. Immunofluorescence analyses of LC3 and Beclin 1 provide additional details that reveal a complex, cell-specific scenario. Autophagy is first activated (1 dpi) in the severed axons, followed by a later (7 dpi) accumulation of phagophores and/or autophagosomes in the neuronal soma without signs of increased initiation. Oligodendrocytes and reactive astrocytes also accumulate phagophores and autophagosomes at 7 dpi, but whereas the accumulation in astrocytes is associated with an increased autophagy initiation, it seems to result from a blockage of the autophagic flux in oligodendrocytes. Comparison with previous studies highlights the complex and heterogeneous autophagic responses induced by the SCI, leading in many cases to contradictory results and interpretations. Future studies should consider this complexity in the design of therapeutic interventions based on the modulation of autophagy to treat SCI.
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Affiliation(s)
- Teresa Muñoz-Galdeano
- Laboratory of Molecular Neuroprotection, UDI-HNP, Hospital Nacional de Parapléjicos (SESCAM), Toledo, Spain
| | - David Reigada
- Laboratory of Molecular Neuroprotection, UDI-HNP, Hospital Nacional de Parapléjicos (SESCAM), Toledo, Spain
| | - Ángela Del Águila
- Laboratory of Molecular Neuroprotection, UDI-HNP, Hospital Nacional de Parapléjicos (SESCAM), Toledo, Spain.,Division of Developmental Biology, Cincinnati Children's Hospital Medical Center, Cincinnati, OH, United States
| | - Irene Velez
- Laboratory of Molecular Neuroprotection, UDI-HNP, Hospital Nacional de Parapléjicos (SESCAM), Toledo, Spain
| | - Marcos J Caballero-López
- Laboratory of Molecular Neuroprotection, UDI-HNP, Hospital Nacional de Parapléjicos (SESCAM), Toledo, Spain
| | - Rodrigo M Maza
- Laboratory of Molecular Neuroprotection, UDI-HNP, Hospital Nacional de Parapléjicos (SESCAM), Toledo, Spain
| | - Manuel Nieto-Díaz
- Laboratory of Molecular Neuroprotection, UDI-HNP, Hospital Nacional de Parapléjicos (SESCAM), Toledo, Spain
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Hydrogen-Rich Saline Activated Autophagy via HIF-1 α Pathways in Neuropathic Pain Model. BIOMED RESEARCH INTERNATIONAL 2018; 2018:4670834. [PMID: 29888265 PMCID: PMC5985079 DOI: 10.1155/2018/4670834] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 07/16/2017] [Revised: 10/04/2017] [Accepted: 10/26/2017] [Indexed: 12/01/2022]
Abstract
Background Neuropathic pain is a chronic and intractable pain, with very few effective analgesics. It involves an impaired cell autophagy process. Hydrogen-rich saline (HRS) reportedly reduces allodynia and hyperalgesia in a neuropathic pain model; however, it is unknown whether these effects involve autophagy induction. Methods We investigated the relationship between HRS and cell autophagy in a neuropathic pain model generated by chronic constriction injury (CCI) in Sprague–Dawley rats. Rats received an intraperitoneal injection of HRS (10 mL/kg daily, from 1 day before until 14 days after CCI), 3MA (autophagy inhibitor), 2ME2 (HIF-1α inhibitor), or EDHB (HIF-1α agonist). The mechanical withdrawal threshold (MWT) and thermal withdrawal latency (TWL) were tested 1 day before and 1, 3, 7, 10, and 14 days after the operation. HIF-1α and cell autophagy markers in the spinal cord were evaluated by western blotting and real-time PCR assays at 14 days after CCI. Autophagosomes with double membranes were identified by transmission electron microscopy. Results CCI caused behavioral hypersensitivity to mechanical and thermal stimulation in the hind-paw of the injured side. HRS improved MWT and TWL, activated autophagy, and increased autophagosomes and autolysosomes in CCI rats. 3-MA aggravated hyperalgesia and allodynia and suppressed autophagy, while EDHB attenuated hyperalgesia and activated the autophagy procedure and the HIF-1α downstream target gene BNIP3. HIF-1α inhibitors reversed the regulatory effects of HRS on autophagy in CCI rats at 14 days after spinal cord injury. Conclusion HRS reduced mechanical hyperalgesia and activation of cell autophagy in neuropathic pain through a HIF1-dependent pathway.
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Zhao Z, Li X, Li Q. Curcumin accelerates the repair of sciatic nerve injury in rats through reducing Schwann cells apoptosis and promoting myelinization. Biomed Pharmacother 2017. [PMID: 28622711 DOI: 10.1016/j.biopha.2017.05.099] [Citation(s) in RCA: 57] [Impact Index Per Article: 8.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/20/2023] Open
Abstract
BACKGROUND Schwann cells (SCs) play an indispensable role in the repair and regeneration of injured peripheral nerve. Curcumin can reduce SCs apoptosis, and promote the regeneration and functional recovery of injured peripheral nerves. However, the corresponding mechanisms are not clear. OBJECTIVE The article was aimed to explore the effect and corresponding mechanisms of curcumin on the repair of sciatic nerve injury in rats. METHODS After surgery induced sciatic nerve injury, the model rats were divided into three groups and treated with curcumin, curcumin+PD98059 and curcumin+IGF-1 respectively for 4days. The phosphorylation of Erk1/2 and Akt, and the expression of LC3-II, Beclin 1 and p62 were measured using western blotting. After treatment for 60days, myelination of the injured sciatic nerve was evaluated by MBP immunohistochemical staining and the expression of PMP22, Fibrin and S100 were determined using qRT-PCR and western blotting. In vitro, RSC96 cells were starved for 12h to induce autophagy, and received DMSO, curcumin, PD98059+curcumin, IGF-1+curcumin and BFA1 respectively. The phosphorylation of Erk1/2、Akt and the expression of LC3-II, Beclin 1, p62, PMP22, Fibrin and S100 were measured using western blotting, and the cell apoptosis was detected by flow cytometry. RESULTS Curcumin could promote injury-induced cell autophagy, remyelination and axon regeneration in sciatic nerve of rats. In vitro, curcumin could accelerate cell autophagy through regulating autophagy related Erk1/2 and Akt pathway, prevent cell apoptosis and promote expression of PMP22 and S100, and reduced deposition of Fibrin in cultured RSC96 SCs. CONCLUSIONS Curcumin could accelerate injured sciatic nerve repair in rats through reducing SCs apoptosis and promoting myelinization.
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Affiliation(s)
- Zhiwei Zhao
- Luoyang Orthopedic Hospital of Henan Province, Zhengzhou 450046, Henan Province, China
| | - Xiaoling Li
- Luoyang Orthopedic Hospital of Henan Province, Zhengzhou 450046, Henan Province, China.
| | - Qing Li
- Department of Orthopaedics, The First Affiliated Hospital of Kunming Medical University, 295 Xichang Road, Kunming 650032, Yunnan Province, China.
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Lipinski MM, Wu J, Faden AI, Sarkar C. Function and Mechanisms of Autophagy in Brain and Spinal Cord Trauma. Antioxid Redox Signal 2015; 23:565-77. [PMID: 25808205 PMCID: PMC4545370 DOI: 10.1089/ars.2015.6306] [Citation(s) in RCA: 147] [Impact Index Per Article: 16.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/25/2023]
Abstract
SIGNIFICANCE Traumatic brain injury (TBI) and spinal cord injury (SCI) are major causes of death and long-term disability worldwide. Despite important pathophysiological differences between these disorders, in many respects, mechanisms of injury are similar. During both TBI and SCI, some cells are directly mechanically injured, but more die as a result of injury-induced biochemical changes (secondary injury). Autophagy, a lysosome-dependent cellular degradation pathway with neuroprotective properties, has been implicated both clinically and experimentally in the delayed response to TBI and SCI. However, until recently, its mechanisms and function remained unknown, reflecting in part the difficulty of isolating autophagic processes from ongoing cell death and other cellular events. RECENT ADVANCES Emerging data suggest that depending on the location and severity of traumatic injury, autophagy flux--defined as the progress of cargo through the autophagy system and leading to its degradation--may be either increased or decreased after central nervous system trauma. CRITICAL ISSUES While increased autophagy flux may be protective after mild injury, after more severe trauma inhibition of autophagy flux may contribute to neuronal cell death, indicating disruption of autophagy as a part of the secondary injury mechanism. FUTURE DIRECTIONS Augmentation and/or restoration of autophagy flux may provide a potential therapeutic target for treatment of TBI and SCI. Development of those treatments will require thorough characterization of changes in autophagy flux, its mechanisms and function over time after injury.
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Affiliation(s)
- Marta M Lipinski
- Department of Anesthesiology and Shock, Trauma and Anesthesiology Research (STAR) Center, University of Maryland School of Medicine , Baltimore, Maryland
| | - Junfang Wu
- Department of Anesthesiology and Shock, Trauma and Anesthesiology Research (STAR) Center, University of Maryland School of Medicine , Baltimore, Maryland
| | - Alan I Faden
- Department of Anesthesiology and Shock, Trauma and Anesthesiology Research (STAR) Center, University of Maryland School of Medicine , Baltimore, Maryland
| | - Chinmoy Sarkar
- Department of Anesthesiology and Shock, Trauma and Anesthesiology Research (STAR) Center, University of Maryland School of Medicine , Baltimore, Maryland
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Increased autophagic activity in dorsal root ganglion attenuates neuropathic pain following peripheral nerve injury. Neurosci Lett 2015; 599:158-63. [DOI: 10.1016/j.neulet.2015.05.046] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/31/2015] [Revised: 05/12/2015] [Accepted: 05/21/2015] [Indexed: 01/01/2023]
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Zhang E, Yi MH, Shin N, Baek H, Kim S, Kim E, Kwon K, Lee S, Kim HW, Chul Bae Y, Kim Y, Kwon OY, Lee WH, Kim DW. Endoplasmic reticulum stress impairment in the spinal dorsal horn of a neuropathic pain model. Sci Rep 2015; 5:11555. [PMID: 26109318 PMCID: PMC4479804 DOI: 10.1038/srep11555] [Citation(s) in RCA: 47] [Impact Index Per Article: 5.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/13/2015] [Accepted: 05/28/2015] [Indexed: 12/19/2022] Open
Abstract
Endoplasmic reticulum (ER) stress has been implicated in neurodegenerative diseases, but its role in neuropathic pain remains unclear. In this study, we examined the ER stress and the unfolded protein response (UPR) activation in a L5 spinal nerve ligation (SNL)-induced rat neuropathic pain model. SNL-induced neuropathic pain was assessed behaviorally using the CatWalk system, and histologically with microglial activation in the dorsal spinal horn. L5 SNL induced BIP upregulation in the neuron of superficial laminae of dorsal spinal horn. It also increased the level of ATF6 and intracellular localization into the nuclei in the neurons. Moreover, spliced XBP1 was also markedly elevated in the ipsilateral spinal dorsal horn. The PERK-elF2 pathway was activated in astrocytes of the spinal dorsal horn in the SNL model. In addition, electron microscopy revealed the presence of swollen cisternae in the dorsal spinal cord after SNL. Additionally, inhibition of the ATF6 pathway by intrathecal treatment with ATF6 siRNA reduced pain behaviors and BIP expression in the dorsal horn. The results suggest that ER stress might be involved in the induction and maintenance of neuropathic pain. Furthermore, a disturbance in UPR signaling may render the spinal neurons vulnerable to peripheral nerve injury or neuropathic pain stimuli.
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Affiliation(s)
- Enji Zhang
- 1] Department of Anatomy, Brain Research Institute, Chungnam National University School of Medicine, Daejeon 301-747, South Korea [2] Department of Anesthesiology, Yanbian University Hospital, Yanbian, 133000, China
| | - Min-Hee Yi
- Department of Anatomy, Brain Research Institute, Chungnam National University School of Medicine, Daejeon 301-747, South Korea
| | - Nara Shin
- Department of Anatomy, Brain Research Institute, Chungnam National University School of Medicine, Daejeon 301-747, South Korea
| | - Hyunjung Baek
- Department of Anatomy, Brain Research Institute, Chungnam National University School of Medicine, Daejeon 301-747, South Korea
| | - Sena Kim
- Department of Anatomy, Brain Research Institute, Chungnam National University School of Medicine, Daejeon 301-747, South Korea
| | - Eunjee Kim
- Department of Anatomy, Brain Research Institute, Chungnam National University School of Medicine, Daejeon 301-747, South Korea
| | - Kisang Kwon
- Department of Anatomy, Brain Research Institute, Chungnam National University School of Medicine, Daejeon 301-747, South Korea
| | - Sunyeul Lee
- Department of Anesthesia and Pain Medicine, Chungnam National University Hospital, Daejeon 301-721, South Korea
| | - Hyun-Woo Kim
- Department of Physiology, Brain Research Institute, Chungnam National University School of Medicine, Daejeon 301-747, South Korea
| | - Yong Chul Bae
- Department of Oral Anatomy and Neurobiology, School of Dentistry, Kyungpook National University, Daegu 700-412, South Korea
| | - Yonghyun Kim
- Department of Chemical and Biological Engineering, The University of Alabama, Tuscaloosa, AL, USA
| | - O-Yu Kwon
- Department of Anatomy, Brain Research Institute, Chungnam National University School of Medicine, Daejeon 301-747, South Korea
| | - Won Hyung Lee
- Department of Anesthesia and Pain Medicine, Chungnam National University Hospital, Daejeon 301-721, South Korea
| | - Dong Woon Kim
- Department of Anatomy, Brain Research Institute, Chungnam National University School of Medicine, Daejeon 301-747, South Korea
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Berliocchi L, Maiarù M, Varano GP, Russo R, Corasaniti MT, Bagetta G, Tassorelli C. Spinal autophagy is differently modulated in distinct mouse models of neuropathic pain. Mol Pain 2015; 11:3. [PMID: 25645145 PMCID: PMC4417307 DOI: 10.1186/1744-8069-11-3] [Citation(s) in RCA: 48] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/14/2014] [Accepted: 01/06/2015] [Indexed: 12/11/2022] Open
Abstract
Background Autophagy is a homeostatic degradative process essential for basal turnover of long-lived proteins and organelles as well as for removal of dysfunctional cellular components. Dysregulation of the autophagic machinery has been recently associated to several conditions including neurodegenerative diseases and cancer, but only very few studies have investigated its role in pain processing. Results We previously described autophagy impairment at the spinal cord in the experimental model of neuropathic pain induced by spinal nerve ligation (SNL). In this study, we characterized the main autophagic markers in two other common experimental models of neuropathic pain, the chronic constriction injury (CCI) and the spared nerve injury (SNI). The different modulation of LC3-I, Beclin 1 and p62 suggested that autophagy is differentially affected in the spinal dorsal horn depending on the type of peripheral injury. Confocal analysis of p62 distribution in the spinal dorsal horn indicated its presence mainly in NeuN-positive cell bodies and occasionally in glial processes, thus suggesting a predominant expression in the neuronal compartment. Finally, we investigated the consequences of autophagy impairment on pain behaviour by using the autophagy blocker cloroquine. Intrathecal chloroquine injection in naïve mice induced spinal accumulation of LC3 and p62 paralleled by significant mechanical hypersensitivity thus confirming the block in autophagosome clearance and suggesting the participation of the autophagic process in spinal mechanisms of pain processing. Altogether, our data indicate that spinal autophagy is differentially altered in different experimental pain models of neuropathic pain and that this process may be relevant for pain control.
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Affiliation(s)
- Laura Berliocchi
- Department of Health Sciences, University "Magna Græcia" of Catanzaro, 88100, Catanzaro, Italy. .,Centre of Neuropharmacology of Normal and Pathological Synaptic Plasticity, University Consortium for Adaptive Disorders and Head Pain, 87036, Rende, Cosenza, Italy.
| | - Maria Maiarù
- Department of Pharmacy, Health and Nutritional Sciences, Section of Preclinical and Translational Pharmacology, University of Calabria, 87036, Rende, Cosenza, Italy.
| | | | - Rossella Russo
- Department of Pharmacy, Health and Nutritional Sciences, Section of Preclinical and Translational Pharmacology, University of Calabria, 87036, Rende, Cosenza, Italy.
| | | | - Giacinto Bagetta
- Centre of Neuropharmacology of Normal and Pathological Synaptic Plasticity, University Consortium for Adaptive Disorders and Head Pain, 87036, Rende, Cosenza, Italy. .,Department of Pharmacy, Health and Nutritional Sciences, Section of Preclinical and Translational Pharmacology, University of Calabria, 87036, Rende, Cosenza, Italy.
| | - Cristina Tassorelli
- C. Mondino National Neurological Institute, Pavia, Italy. .,Department of Brain and Behavioral Sciences, University of Pavia, Pavia, Italy.
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Rapamycin ameliorates neuropathic pain by activating autophagy and inhibiting interleukin-1β in the rat spinal cord. ACTA ACUST UNITED AC 2014; 34:830-837. [DOI: 10.1007/s11596-014-1361-6] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/24/2014] [Revised: 09/22/2014] [Indexed: 12/13/2022]
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Adenoviral-mediated glial cell line-derived neurotrophic factor gene transfer has a protective effect on sciatic nerve following constriction-induced spinal cord injury. PLoS One 2014; 9:e92264. [PMID: 24642655 PMCID: PMC3958488 DOI: 10.1371/journal.pone.0092264] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/22/2013] [Accepted: 02/20/2014] [Indexed: 12/30/2022] Open
Abstract
Neuropathic pain due to peripheral nerve injury may be associated with abnormal central nerve activity. Glial cell-line-derived neurotrophic factor (GDNF) can help attenuate neuropathic pain in different animal models of nerve injury. However, whether GDNF can ameliorate neuropathic pain in the spinal cord dorsal horn (SCDH) in constriction-induced peripheral nerve injury remains unknown. We investigated the therapeutic effects of adenoviral-mediated GDNF on neuropathic pain behaviors, microglial activation, pro-inflammatory cytokine expression and programmed cell death in a chronic constriction injury (CCI) nerve injury animal model. In this study, neuropathic pain was produced by CCI on the ipsilateral SCDH. Mechanical allodynia was examined with von Frey filaments and thermal sensitivity was tested using a plantar test apparatus post-operatively. Target proteins GDNF-1, GDNFRa-1, MMP2, MMP9, p38, phospho-p38, ED1, IL6, IL1β, AIF, caspase-9, cleaved caspase-9, caspase-3, cleaved caspase-3, PARP, cleaved PARP, SPECTRIN, cleaved SPECTRIN, Beclin-1, PKCσ, PKCγ, iNOS, eNOS and nNOS were detected. Microglial activity was measured by observing changes in immunoreactivity with OX-42. NeuN and TUNEL staining were used to reveal whether apoptosis was attenuated by GDNF. Results showed that administrating GDNF began to attenuate both allodynia and thermal hyperalgesia at day 7. CCI-rats were found to have lower GDNF and GDNFRa-1 expression compared to controls, and GDNF re-activated their expression. Also, GDNF significantly down-regulated CCI-induced protein expression except for MMP2, eNOS and nNOS, indicating that the protective action of GDNF might be associated with anti-inflammation and prohibition of microglia activation. Immunocytochemistry staining showed that GDNF reduced CCI-induced neuronal apoptosis. In sum, GDNF enhanced the neurotrophic effect by inhibiting microglia activation and cytokine production via p38 and PKC signaling. GDNF could be a good therapeutic tool to attenuate programmed cell death, including apoptosis and autophagy, consequent to CCI-induced peripheral nerve injury.
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