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Peng Y, Chen X, Rao Z, Wu W, Zuo H, Chen K, Li K, Lin H, Liu S, Xiao Y, Wang B, Quan D, Qing X, Bai Y, Shao Z. Multifunctional annulus fibrosus matrix prevents disc-related pain via inhibiting neuroinflammation and sensitization. Acta Biomater 2023; 170:288-302. [PMID: 37598791 DOI: 10.1016/j.actbio.2023.08.028] [Citation(s) in RCA: 5] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/16/2023] [Revised: 07/25/2023] [Accepted: 08/15/2023] [Indexed: 08/22/2023]
Abstract
Chronic low back pain mainly attributed to intervertebral disc (IVD) degeneration. Endogenous damage-associated molecular patterns (DAMPs) in the injured IVD, particularly mitochondria-derived nucleic acid molecules (CpG DNA), play a primary role in the inflammatory responses in macrophages. M1-type macrophages form a chronic inflammatory microenvironment by releasing pro-inflammatory factors and nerve growth factor (NGF) that induce nerve growth into the inner annulus fibrosus, resulting in persistent hyperalgesia. We fabricated an amphiphilic polycarbonate that naturally forms cationic nanoparticles (cNP) in aqueous solutions, with the hydrophobic core loaded with TrkA-IN-1, an antagonist against the NGF receptor (TrkA). The drug delivery nanoparticles were denoted as TI-cNP. TrkA-IN-1 and TI-cNP were added to the decellularized annulus fibrosus matrix (DAF) hydrogel to form hybrid hydrogels, denoted as TI-DAF and TI-cNP-DAF, respectively. As a result, TrkA-IN-1 showed a delayed release profile both in TI-DAF and TI-cNP-DAF. Each mole of cNP could bind approximately 3 mol of CpG DNA to inhibit inflammation. cNP-DAF and TI-cNP-DAF significantly inhibited the M1 phenotype induced by CpG DNA. TI-DAF and TI-cNP-DAF reduced neurite branching and axon length, and inhibited the expression of neurogenic mediators (CGRP and substance P) in the presence of NGF. Besides, TI-cNP-DAF relieved mechanical hyperalgesia, reduced CGRP and substance P expression in the dorsal root ganglion, and downregulated GFAP and c-FOS signaling in the spinal cord in the rat disc herniation model. Summarily, TI-cNP-DAF, a novel composite IVD hydrogel, efficiently mediated the inflammatory environment, inhibited nerve ingrowth and sensitization, and could be clinically applied for treating discogenic pain. STATEMENT OF SIGNIFICANCE: Discogenic lower back pain, related to intervertebral disc degeneration (IDD), imposes a tremendous health and economic burden globally. M1-type macrophages release pro-inflammatory factors and nerve growth factor (NGF) that induce nerve growth into the inner annulus fibrosus, resulting in persistent hyperalgesia and discogenic pain. Reconstructing matrix integrity and modulating the inflammatory microenvironment are promising strategies for preventing the ingrowth and activation of neurites. The TI-cNP-DAF hydrogel recovers tissue integrity, alleviates inflammation, and delivers the TrkA antagonist to inhibit the activity of NGF, thus restraining hyperinnervation and nociceptive input. Due to its simple production process, injectability, and acellular strategy, the hydrogel is operable and holds great potential for treating discogenic lower back pain.
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Affiliation(s)
- Yizhong Peng
- Department of Orthopaedics, Union Hospital, Tongji Medical College, Huazhong University of Science and Technology, Wuhan 430022, China
| | - Xuanzuo Chen
- Department of Orthopaedics, Union Hospital, Tongji Medical College, Huazhong University of Science and Technology, Wuhan 430022, China
| | - Zilong Rao
- School of Materials Science and Engineering, Sun Yat-sen University, Guangzhou 510127, China
| | - Wei Wu
- Department of Orthopaedics, Union Hospital, Tongji Medical College, Huazhong University of Science and Technology, Wuhan 430022, China
| | - Huiying Zuo
- School of Materials Science and Engineering, Sun Yat-sen University, Guangzhou 510127, China
| | - Kaibin Chen
- School of Materials Science and Engineering, Sun Yat-sen University, Guangzhou 510127, China
| | - Kanglu Li
- Department of Orthopaedics, Union Hospital, Tongji Medical College, Huazhong University of Science and Technology, Wuhan 430022, China
| | - Hui Lin
- Department of Orthopaedics, Union Hospital, Tongji Medical College, Huazhong University of Science and Technology, Wuhan 430022, China
| | - Sheng Liu
- Department of Orthopaedics, Union Hospital, Tongji Medical College, Huazhong University of Science and Technology, Wuhan 430022, China
| | - Yan Xiao
- Department of Radiology, Union Hospital, Tongji Medical College, Huazhong University of Science and Technology, Wuhan 430022, China
| | - BaiChuan Wang
- Department of Orthopaedics, Union Hospital, Tongji Medical College, Huazhong University of Science and Technology, Wuhan 430022, China
| | - Daping Quan
- School of Materials Science and Engineering, Sun Yat-sen University, Guangzhou 510127, China
| | - Xiangcheng Qing
- Department of Orthopaedics, Union Hospital, Tongji Medical College, Huazhong University of Science and Technology, Wuhan 430022, China.
| | - Ying Bai
- School of Materials Science and Engineering, Sun Yat-sen University, Guangzhou 510127, China.
| | - Zengwu Shao
- Department of Orthopaedics, Union Hospital, Tongji Medical College, Huazhong University of Science and Technology, Wuhan 430022, China.
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Paquette T, Eskandari N, Leblond H, Piché M. Spinal neurovascular coupling is preserved despite time-dependent alterations of spinal cord blood flow responses in a rat model of chronic back pain: implications for functional spinal cord imaging. Pain 2023; 164:758-770. [PMID: 36036900 DOI: 10.1097/j.pain.0000000000002762] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/20/2022] [Accepted: 08/15/2022] [Indexed: 11/26/2022]
Abstract
ABSTRACT Functional magnetic resonance imaging has been used to investigate nociceptive processes in patients with chronic pain. However, the results may be confounded with changes in neurovascular coupling induced by chronic pain. The objective of this study was to examine spinal neurovascular coupling in a rat model of chronic back pain induced by muscle inflammation. Rats received 150 µL intramuscular injections of either complete Freund adjuvant (CFA: n = 18) or saline (control [CTL]: n = 18) in L5-L6 paravertebral muscles. Under 1.2% isoflurane anesthesia, spinal cord blood flow (SCBF) and local field potentials evoked by electrical stimulation of the sciatic nerve were recorded simultaneously in the lumbar enlargement of the spinal cord, 14 or 28 days after the injections. Mechanical hypersensitivity was observed in CFA rats compared with CTL rats for the back ( P < 0.001) and hind paws ( P < 0.01). Spinal cord blood flow response amplitude and local field potential amplitude were not significantly different between groups (day 14: P > 0.5; day 28: P > 0.6). However, the time course of SCBF responses was different between groups on day 14 ( P < 0.001) and day 28 ( P < 0.001). Nevertheless, neurovascular coupling was comparable between groups on days 14 and 28, whether neurovascular coupling was calculated with the amplitude or the area under the curve of SCBF responses (all P > 0.2). These results indicate that spinal hemodynamic changes reflect neuronal activity in this animal model, although the time course of SCBF responses is affected by chronic inflammatory back pain. This warrants a careful use of spinal functional magnetic resonance imaging in animal models and patients with chronic back pain.
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Affiliation(s)
- Thierry Paquette
- Department of Anatomy, Université du Québec à Trois-Rivières, Trois-Rivières, QC, Canada
- CogNAC Research Group, Université du Québec à Trois-Rivières, Trois-Rivières, QC, Canada
| | - Nasim Eskandari
- Department of Anatomy, Université du Québec à Trois-Rivières, Trois-Rivières, QC, Canada
- CogNAC Research Group, Université du Québec à Trois-Rivières, Trois-Rivières, QC, Canada
| | - Hugues Leblond
- Department of Anatomy, Université du Québec à Trois-Rivières, Trois-Rivières, QC, Canada
- CogNAC Research Group, Université du Québec à Trois-Rivières, Trois-Rivières, QC, Canada
| | - Mathieu Piché
- Department of Anatomy, Université du Québec à Trois-Rivières, Trois-Rivières, QC, Canada
- CogNAC Research Group, Université du Québec à Trois-Rivières, Trois-Rivières, QC, Canada
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Lillyman DJ, Lee FS, Barnett EC, Miller TJ, Alvaro ML, Drvol HC, Wachs RA. Axial hypersensitivity is associated with aberrant nerve sprouting in a novel model of disc degeneration in female Sprague Dawley rats. JOR Spine 2022; 5:e1212. [PMID: 36203864 PMCID: PMC9520768 DOI: 10.1002/jsp2.1212] [Citation(s) in RCA: 8] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 03/15/2022] [Revised: 05/26/2022] [Accepted: 06/07/2022] [Indexed: 11/30/2022] Open
Abstract
Chronic low back pain is a global socioeconomic crisis and treatments are lacking in part due to inadequate models. Etiological research suggests that the predominant pathology associated with chronic low back pain is intervertebral disc degeneration. Various research teams have created rat models of disc degeneration, but the clinical translatability of these models has been limited by an absence of robust chronic pain-like behavior. To address this deficit, disc degeneration was induced via an artificial annular tear in female Sprague Dawley rats. The subsequent degeneration, which was allowed to progress for 18-weeks, caused a drastic reduction in disc volume. Furthermore, from week 10 till study conclusion, injured animals exhibited significant axial hypersensitivity. At study end, intervertebral discs were assessed for important characteristics of human degenerated discs: extracellular matrix breakdown, hypocellularity, inflammation, and nerve sprouting. All these aspects were significantly increased in injured animals compared to sham controls. Also of note, 20 significant correlations were detected between selected outcomes including a moderate and highly significant correlation (R = 0.59, p < 0.0004) between axial hypersensitivity and disc nerve sprouting. These data support this model as a rigorous platform to explore the pathobiology of disc-associated low back pain and to screen treatments.
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Affiliation(s)
- David J. Lillyman
- Department of Biological Systems EngineeringUniversity of NebraskaLincolnNebraskaUSA
| | - Fei San Lee
- Department of Biological Systems EngineeringUniversity of NebraskaLincolnNebraskaUSA
| | - Evie C. Barnett
- Department of Biological Systems EngineeringUniversity of NebraskaLincolnNebraskaUSA
| | - Tyler J. Miller
- Department of Biological Systems EngineeringUniversity of NebraskaLincolnNebraskaUSA
| | - Moreno Lozano Alvaro
- Department of Biological Systems EngineeringUniversity of NebraskaLincolnNebraskaUSA
| | - Henry C. Drvol
- Department of Biological Systems EngineeringUniversity of NebraskaLincolnNebraskaUSA
| | - Rebecca A. Wachs
- Department of Biological Systems EngineeringUniversity of NebraskaLincolnNebraskaUSA
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Ex vivo biomechanical evaluation of Acute lumbar endplate injury and comparison to annulus fibrosus injury in a rat model. J Mech Behav Biomed Mater 2022; 131:105234. [DOI: 10.1016/j.jmbbm.2022.105234] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/14/2022] [Revised: 03/14/2022] [Accepted: 04/09/2022] [Indexed: 11/20/2022]
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Resveratrol Inhibition of the WNT/β-Catenin Pathway following Discogenic Low Back Pain. Int J Mol Sci 2022; 23:ijms23084092. [PMID: 35456908 PMCID: PMC9024678 DOI: 10.3390/ijms23084092] [Citation(s) in RCA: 7] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/11/2022] [Revised: 04/04/2022] [Accepted: 04/06/2022] [Indexed: 12/26/2022] Open
Abstract
Low back pain (LBP) management is an important clinical issue. Inadequate LBP control has consequences on the mental and physical health of patients. Thus, acquiring new information on LBP mechanism would increase the available therapeutic tools. Resveratrol is a natural compound with many beneficial effects. In this study, we investigated the role of resveratrol on behavioral changes, inflammation and oxidative stress induced by LBP. Ten microliters of Complete Freund’s adjuvant (CFA) was injected in the lumbar intervertebral disk of Sprague Dawley rats to induce degeneration, and resveratrol was administered daily. Behavioral analyses were performed on day zero, three, five and seven, and the animals were sacrificed to evaluate the molecular pathways involved. Resveratrol administration alleviated hyperalgesia, motor disfunction and allodynia. Resveratrol administration significantly reduced the loss of notochordal cells and degenerative changes in the intervertebral disk. From the molecular point of view, resveratrol reduced the 5th/6th lumbar (L5–6) spinal activation of the WNT pathway, reducing the expression of WNT3a and cysteine-rich domain frizzled (FZ)8 and the accumulation of cytosolic and nuclear β-catenin. Moreover, resveratrol reduced the levels of TNF-α and IL-18 that are target genes strictly downstream of the WNT/β-catenin pathway. It also showed important anti-inflammatory activities by reducing the activation of the NFkB pathway, the expression of iNOS and COX-2, and the levels of PGE2 in the lumbar spinal cord. Moreover, resveratrol reduced the oxidative stress associated with inflammation and pain, as shown by the observed reduced lipid peroxidation and increased GSH, SOD, and CAT activities. Therefore, resveratrol administration controlled the WNT/β-catenin pathway and the related inflammatory and oxidative alterations, thus alleviating the behavioral changes induced by LBP.
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Jin L, Xiao L, Ding M, Pan A, Balian G, Sung SSJ, Li XJ. Heterogeneous macrophages contribute to the pathology of disc herniation induced radiculopathy. Spine J 2022; 22:677-689. [PMID: 34718176 PMCID: PMC8957503 DOI: 10.1016/j.spinee.2021.10.014] [Citation(s) in RCA: 10] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 08/02/2021] [Revised: 10/17/2021] [Accepted: 10/18/2021] [Indexed: 02/03/2023]
Abstract
BACKGROUND CONTEXT Macrophages play important roles in the progression of intervertebral disc herniation and radiculopathy. PURPOSE To better understand the roles of macrophages in this process, we developed a new mouse model that mimics human radiculopathy. STUDY DESIGN/SETTING A preclinical randomized animal study. METHODS Three types of surgeries were performed in randomly assigned Balb/c mice. These were spinal nerve exposure, traditional anterior disc puncture, and lateral disc puncture with nerve exposure (n=16/group). For the nerve exposure group, the left L5 spinal nerve was exposed without disc injury. For the traditional anterior puncture, L5/6 disc was punctured by an anterior approach as previously established. For lateral puncture with nerve exposure, the left L5 spinal nerve was exposed by removing the psoas major muscle fibers, and the L5/6 disc was punctured laterally on the left side with a 30G needle, allowing the nucleus to protrude toward the L5 spinal nerve. Mechanical hyperalgesia (pain sensitivity) of hind paws was assessed with electronic von Frey assay on alternative day for up to 2 weeks. MRI, histology, and immunostaining were performed to confirm disc herniation and inflammation. RESULTS Ipsilateral pain in the lateral puncture with nerve exposure group was significantly greater than the other groups. Pro-inflammatory cytokines IL-1β and IL-6 were markedly elevated at the hernia sites of both puncture groups and the spinal nerve of lateral puncture with never exposure group on postoperative day 7. Heterogeneous populations of macrophages were detected in the infiltration tissue of this mouse model and in tissue from patients undergone discectomy. CONCLUSIONS We have established a new mouse model that mimics human radiculopathy and demonstrated that a mixed phenotype of macrophages contribute to the pathogenesis of acute discogenic radiculopathy. CLINICAL SIGNIFICANCE This study provides a clinically relevant in vivo animal model to elucidate complex interactions of disc herniation and radicular pain, which may present opportunities for the development of macrophage-anchored therapeutics to manage radiculopathy.
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Affiliation(s)
- Li Jin
- Department of Orthopaedic Surgery, University of Virginia, Charlottesville, VA 22908, USA
| | - Li Xiao
- Department of Orthopaedic Surgery, University of Virginia, Charlottesville, VA 22908, USA
| | - Mengmeng Ding
- Department of Orthopaedic Surgery, University of Virginia, Charlottesville, VA 22908, USA; Department of Anesthesiology, Shengjing hospital, China Medical University, Shenyang, China
| | - Aixing Pan
- Department of Orthopaedic Surgery, University of Virginia, Charlottesville, VA 22908, USA; Department of Orthopaedic Surgery, Chaoyang Hospital, Capital Medical School, Beijing, China
| | - Gary Balian
- Department of Orthopaedic Surgery, University of Virginia, Charlottesville, VA 22908, USA; Department of Biochemistry and Molecular Genetics, University of Virginia, Charlottesville, VA 22908, USA
| | - Sun-Sang J Sung
- Department of Medicine and Center for Immunity, Inflammation, and Regenerative Medicine, University of Virginia, Charlottesville, VA 22908, USA
| | - Xudong Joshua Li
- Department of Orthopaedic Surgery, University of Virginia, Charlottesville, VA 22908, USA; Department of Biomedical Engineering, University of Virginia, Charlottesville, VA 22904, USA.
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Suh HR, Cho HY, Han HC. Development of a novel model of intervertebral disc degeneration by the intradiscal application of monosodium iodoacetate (MIA) in rat. Spine J 2022; 22:183-192. [PMID: 34118415 DOI: 10.1016/j.spinee.2021.06.008] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 11/18/2020] [Revised: 06/03/2021] [Accepted: 06/07/2021] [Indexed: 02/03/2023]
Abstract
BACKGROUND CONTEXT Low back pain is one of the most common musculoskeletal disorders. Although, the pathology of intervertebral disc (IVD) degeneration has been modeled using various biological methods, these models are inadequate for simulating similar pathologic states in humans. PURPOSE This study investigated whether monosodium iodoacetate (MIA) injection into the IVD of rats could generate a reliable model of IVD degeneration. STUDY DESIGN/SETTINGS In vivo animal study. METHODS MIA was injected into two-disc spaces (L4-5 and L5-6) of Sprague-Dawley rats. Their behaviors were examined by measuring weight load shifts from hind to forefoot, rearing, and von Frey tests. We examined the inhibition of pain behavior through intraperitoneal morphine injection and measured cyclooxygenase-2 (COX-2) and transcription factor nuclear factor-kappa B (NF-κB) levels in the IVD and dorsal root ganglion (DRG) by Western blot. Bone alterations were assessed by microfocus computed tomography (micro-CT), and IVD and/or cartilage changes were evaluated by hematoxylin and eosin and safranin-O staining and inducible nitric oxide synthase (iNOS) immunohistochemistry. The other authors declare no conflicts of interest. This project funded by the Memorial Fund and the National Research Foundation of Korea (NRF). RESULTS We observed increased weight load shifts to the forefoot and decreased rearing. Morphine-injected rats showed reduced pain. NF-κB and COX-2 expression increased in the IVD and left and/or right DRG. Micro-CT analyses suggested progressive bone deformation. Histologic examination showed decreased IVD width and nucleus pulposus area. Cartilaginous changes indicated epiphyseal growth plate loss. Finally, iNOS expression was increased in the subchondral endplate. CONCLUSIONS These results suggest that low back pain (LBP) models can be developed by MIA injection into the IVDs of rats and that an animal model is useful for exploring degenerative alterations in the affected discs. Therefore, MIA injection may be a useful model for the study of changes in the IVD to elucidate the mechanisms underlying clinical symptoms, such as LBP, in patients with IVD degeneration. CLINICAL SIGNIFICANCE This model in which MIA was injected into the disc better represented the human histologic and behavioral characteristics than the existing puncture model.
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Affiliation(s)
- Hye Rim Suh
- Department of Physiology, Korea University, Seoul, Republic of Korea
| | - Hwi-Young Cho
- Department of Physical Therapy, Gachon University, Incheon, Republic of Korea.
| | - Hee Chul Han
- Department of Physiology, Korea University, Seoul, Republic of Korea.
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Huang Y, Wang L, Luo B, Yang K, Zeng X, Chen J, Zhang Z, Li Y, Cheng X, He B. Associations of Lumber Disc Degeneration With Paraspinal Muscles Myosteatosis in Discogenic Low Back Pain. Front Endocrinol (Lausanne) 2022; 13:891088. [PMID: 35634490 PMCID: PMC9136003 DOI: 10.3389/fendo.2022.891088] [Citation(s) in RCA: 6] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 03/07/2022] [Accepted: 04/13/2022] [Indexed: 11/13/2022] Open
Abstract
Accompanied with intervertebral disc (IVD) degeneration, increasing fat infiltration of paraspinal muscles may be related to discogenic low back pain (DLBP), but their relationship is still unclear and the classical animal models are not completely applicable. The purpose of this study was to assess the paraspinal muscle fat infiltration in patients with DLBP by quantitative MRI, and to develop a novel DLBP rat model to explore the potential relationship between DLBP paraspinal muscle fat infiltration and TNF-α levels. We measured the proton density fat fraction (PDFF) of the multifidus and erector spinae muscles of 70 DLBP patients and 36 healthy volunteers by using quantitative MRI IDEAL-IQ. In addition, we developed a DLBP experimental rat model by puncturing the L4/5 and L5/6 IVDs under the guidance of X-ray fluoroscopy. Then various behavioral experiments, MRI and pathological examination of IVDs were used to evaluate the performance of the DLBP animal model. The gait analysis, hot plate test, acetone test, grasping test and tail suspension test were used to evaluate the pain and muscle dysfunction in rats. Through quantitative MRI and histological examination, the degeneration of IVDs and fat infiltration in the muscles were observed in vivo and ex vivo. Enzyme linked immunosorbent assay detects the level of TNF-α in rat IVDs and paraspinal muscles. In the human study, compared with healthy volunteers, the PDFF of multifidus and erector muscles of DLBP patients increased significantly at L4/5 and L5/S1 levels (p<0.05). In the rat experiment, compared with control group and sham group, DLBP group had reduced gait score, shortened response time to cold and heat stimuli, prolonged bending time, and shortened struggling time. Rat lumbar MRI T2WI showed that the signal intensity of L4/5 and L5/6 IVDs were progressively decreased. Histological examination revealed that IVDs had increased collagen fibers, reduced nucleus pulposus, thickened annulus fibrosus, and distorted shape. The PDFF of multifidus muscle at L4/5 and L5/6 level in the DLBP group were more than that in other groups (p<0.05), and HE staining and oil red O staining of paraspinal muscles showed that the muscle bundle space of the DLBP group muscles increased, and the muscle tissues Increased lipid droplets. Finally, the expression of TNF-α in IVDs and paraspinal muscles in the DLBP group were significantly higher than that in the control group (p<0.05). It is reliable and feasible to establish a DLBP rat model by puncturing the lumbar IVDs under the guidance of X-ray fluoroscopy. The degeneration of lumbar IVDs with DLBP leads to the occurrence of fat infiltration of paraspinal muscles, which is related to the expression of TNF-α.
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Affiliation(s)
- Yilong Huang
- Department of Medical Imaging, The First Affiliated Hospital of Kunming Medical University, Kunming, China
| | - Ling Wang
- Department of Radiology, Beijing Jishuitan Hospital, Beijing, China
| | - Baofa Luo
- Department of Medical Imaging, The First Affiliated Hospital of Kunming Medical University, Kunming, China
| | - Kaiwen Yang
- Department of Medical Imaging, The First Affiliated Hospital of Kunming Medical University, Kunming, China
| | - Xiaomin Zeng
- Department of Medical Imaging, The First Affiliated Hospital of Kunming Medical University, Kunming, China
| | - Jiaxin Chen
- Department of Medical Imaging, The First Affiliated Hospital of Kunming Medical University, Kunming, China
| | - Zhenguang Zhang
- Department of Medical Imaging, The First Affiliated Hospital of Kunming Medical University, Kunming, China
| | - Yanlin Li
- Department of Sports Medicine, The First Affiliated Hospital of Kunming Medical University, Kunming, China
| | - Xiaoguang Cheng
- Department of Radiology, Beijing Jishuitan Hospital, Beijing, China
| | - Bo He
- Department of Medical Imaging, The First Affiliated Hospital of Kunming Medical University, Kunming, China
- *Correspondence: Bo He,
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Wang Y, Kang J, Guo X, Zhu D, Liu M, Yang L, Zhang G, Kang X. Intervertebral Disc Degeneration Models for Pathophysiology and Regenerative Therapy -Benefits and Limitations. J INVEST SURG 2021; 35:935-952. [PMID: 34309468 DOI: 10.1080/08941939.2021.1953640] [Citation(s) in RCA: 11] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/07/2023]
Abstract
Aim:This review summarized the recent intervertebral disc degeneration (IDD) models and described their advantages and potential disadvantages, aiming to provide an overview for the current condition of IDD model establishment and new ideas for new strategies development of the treatment and prevention of IDD.Methods:The database of PubMed was searched up to May 2021 with the following search terms: nucleus pulposus, annulus fibrosus, cartilage endplate, intervertebral disc(IVD), intervertebral disc degeneration, animal model, organ culture, bioreactor, inflammatory reaction, mechanical stress, pathophysiology, epidemiology. Any IDD model-related articles were collected and summarized.Results:The best IDD model should have the features of repeatability, measurability and controllability. There are a lot of aspects to be considered in the selection of animals. Mice, rats and rabbits are low-cost and easy to access. However, their IVD size and shape are more different from human anatomy than pigs, cattle, sheep and goats. Organ culture models and animal models are two options in model establishment for IDD. The IVD organ culture model can put the studying variables into the controllable system for transitional research. Unlike the animal model, the organ culture model can only be used to evaluate the short-term effects and it is not applicable in simulating the complex process of IDD. Similarly, the animal models induced by different methods also have their advantages and disadvantages. For studying the mechanism of IDD and the corresponding treatment and prevention strategies, the selection of model should be individualized based on the purpose of each study.Conclusions:Various models have different characteristics and scope of application due to their different rationales and methods of construction. Currently, there is no experimental model that can perfectly mimic the degenerative process of human IVD. Personalized selection of appropriate model based on study purpose and experimental designing can enhance the possibility to obtain reliable and real results.
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Affiliation(s)
- Yidian Wang
- The Second Clinical Medical College, Lanzhou University, Lanzhou, P.R. China
| | - Jihe Kang
- The Second Clinical Medical College, Lanzhou University, Lanzhou, P.R. China
| | - Xudong Guo
- The Second Clinical Medical College, Lanzhou University, Lanzhou, P.R. China
| | - Daxue Zhu
- The Second Clinical Medical College, Lanzhou University, Lanzhou, P.R. China
| | - Mingqiang Liu
- The Second Clinical Medical College, Lanzhou University, Lanzhou, P.R. China
| | - Liang Yang
- The Second Clinical Medical College, Lanzhou University, Lanzhou, P.R. China
| | - Guangzhi Zhang
- The Second Clinical Medical College, Lanzhou University, Lanzhou, P.R. China
| | - Xuewen Kang
- The Second Clinical Medical College, Lanzhou University, Lanzhou, P.R. China.,Department of Orthopedics, Lanzhou University Second Hospital, Lanzhou, P.R. China.,The International Cooperation Base of Gansu Province for The Pain Research in Spinal Disorders, Gansu, P.R. China
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10
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Lyu FJ, Cui H, Pan H, MC Cheung K, Cao X, Iatridis JC, Zheng Z. Painful intervertebral disc degeneration and inflammation: from laboratory evidence to clinical interventions. Bone Res 2021; 9:7. [PMID: 33514693 PMCID: PMC7846842 DOI: 10.1038/s41413-020-00125-x] [Citation(s) in RCA: 195] [Impact Index Per Article: 65.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/02/2020] [Revised: 10/01/2020] [Accepted: 10/09/2020] [Indexed: 02/06/2023] Open
Abstract
Low back pain (LBP), as a leading cause of disability, is a common musculoskeletal disorder that results in major social and economic burdens. Recent research has identified inflammation and related signaling pathways as important factors in the onset and progression of disc degeneration, a significant contributor to LBP. Inflammatory mediators also play an indispensable role in discogenic LBP. The suppression of LBP is a primary goal of clinical practice but has not received enough attention in disc research studies. Here, an overview of the advances in inflammation-related pain in disc degeneration is provided, with a discussion on the role of inflammation in IVD degeneration and pain induction. Puncture models, mechanical models, and spontaneous models as the main animal models to study painful disc degeneration are discussed, and the underlying signaling pathways are summarized. Furthermore, potential drug candidates, either under laboratory investigation or undergoing clinical trials, to suppress discogenic LBP by eliminating inflammation are explored. We hope to attract more research interest to address inflammation and pain in IDD and contribute to promoting more translational research.
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Affiliation(s)
- Feng-Juan Lyu
- grid.79703.3a0000 0004 1764 3838School of Medicine, South China University of Technology, Guangzhou, China
| | - Haowen Cui
- grid.12981.330000 0001 2360 039XDepartment of Spine Surgery, The First Affiliated Hospital, Sun Yat-Sen University, Guangzhou, China
| | - Hehai Pan
- grid.12981.330000 0001 2360 039XGuangdong Provincial Key Laboratory of Malignant Tumor Epigenetics and Gene Regulation, Sun Yat-sen Memorial Hospital, Sun Yat-sen University, Guangzhou, China ,grid.12981.330000 0001 2360 039XBreast Tumor Center, Sun Yat-sen Memorial Hospital, Sun Yat-sen University, Guangzhou, China
| | - Kenneth MC Cheung
- grid.194645.b0000000121742757Department of Orthopedics & Traumatology, The University of Hong Kong, Hong Kong, SAR China
| | - Xu Cao
- grid.21107.350000 0001 2171 9311Department of Orthopedic Surgery, Johns Hopkins University, Baltimore, MD USA
| | - James C. Iatridis
- grid.59734.3c0000 0001 0670 2351Leni and Peter W. May Department of Orthopedics, Icahn School of Medicine at Mount Sinai, New York, NY USA
| | - Zhaomin Zheng
- grid.12981.330000 0001 2360 039XDepartment of Spine Surgery, The First Affiliated Hospital, Sun Yat-Sen University, Guangzhou, China ,grid.12981.330000 0001 2360 039XPain Research Center, Sun Yat-sen University, Guangzhou, China
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11
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Ren K. Grand Challenges in Musculoskeletal Pain Research: Chronicity, Comorbidity, Immune Regulation, Sex Differences, Diagnosis, and Treatment Opportunities. FRONTIERS IN PAIN RESEARCH 2020; 1. [PMID: 34296207 PMCID: PMC8294784 DOI: 10.3389/fpain.2020.575479] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Key Words] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/22/2023] Open
Affiliation(s)
- Ke Ren
- Department of Neural and Pain Sciences, School of Dentistry, University of Maryland, Baltimore, MD, United States.,Program in Neuroscience, University of Maryland, Baltimore, MD, United States
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12
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Mosley GE, Wang M, Nasser P, Lai A, Charen DA, Zhang B, Iatridis JC. Males and females exhibit distinct relationships between intervertebral disc degeneration and pain in a rat model. Sci Rep 2020; 10:15120. [PMID: 32934258 PMCID: PMC7492468 DOI: 10.1038/s41598-020-72081-9] [Citation(s) in RCA: 29] [Impact Index Per Article: 7.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/05/2020] [Accepted: 08/24/2020] [Indexed: 12/16/2022] Open
Abstract
Back pain is linked to intervertebral disc (IVD) degeneration, but clinical studies show the relationship is complex. This study assessed whether males and females have distinct relationships between IVD degeneration and pain using an in vivo rat model. Forty-eight male and female Sprague-Dawley rats had lumbar IVD puncture or sham surgery. Six weeks after surgery, IVDs were evaluated by radiologic IVD height, histological grading, and biomechanical testing. Pain was assessed by von Frey assay and dorsal root ganglia (DRG) expression of Calca and Tac1 genes. Network analysis visualized which measures of IVD degeneration most related to pain by sex. In both females and males, annular puncture induced structural IVD degeneration, but functional biomechanical properties were similar to sham. Females and males had distinct differences in mechanical allodynia and DRG gene expression, even though sex differences in IVD measurements were limited. Network analysis also differed by sex, with more associations between annular puncture injury and pain in the male network. Sex differences exist in the interactions between IVD degeneration and pain. Limited correlation between measures of pain and IVD degeneration highlights the need to evaluate pain or nociception in IVD degeneration models to better understand nervous system involvement in discogenic pain.
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Affiliation(s)
- Grace E Mosley
- Leni and Peter W. May Department of Orthopaedics, Icahn School of Medicine at Mount Sinai, 1 Gustave Levy, Place, Box 1188, New York, NY, 10029-6574, USA.,Medical Scientist Training Program, Icahn School of Medicine at Mount Sinai, New York, NY, USA
| | - Minghui Wang
- Department of Genetics and Genomic Sciences, Icahn School of Medicine at Mount Sinai, New York, NY, USA.,Mount Sinai Center for Transformative Disease Modeling, Icahn School of Medicine at Mount Sinai, New York, NY, USA.,Icahn Institute for Data Science and Genomic Technology, Icahn School of Medicine at Mount Sinai, New York, NY, USA
| | - Philip Nasser
- Leni and Peter W. May Department of Orthopaedics, Icahn School of Medicine at Mount Sinai, 1 Gustave Levy, Place, Box 1188, New York, NY, 10029-6574, USA
| | - Alon Lai
- Leni and Peter W. May Department of Orthopaedics, Icahn School of Medicine at Mount Sinai, 1 Gustave Levy, Place, Box 1188, New York, NY, 10029-6574, USA
| | - Daniel A Charen
- Leni and Peter W. May Department of Orthopaedics, Icahn School of Medicine at Mount Sinai, 1 Gustave Levy, Place, Box 1188, New York, NY, 10029-6574, USA
| | - Bin Zhang
- Department of Genetics and Genomic Sciences, Icahn School of Medicine at Mount Sinai, New York, NY, USA.,Mount Sinai Center for Transformative Disease Modeling, Icahn School of Medicine at Mount Sinai, New York, NY, USA.,Icahn Institute for Data Science and Genomic Technology, Icahn School of Medicine at Mount Sinai, New York, NY, USA
| | - James C Iatridis
- Leni and Peter W. May Department of Orthopaedics, Icahn School of Medicine at Mount Sinai, 1 Gustave Levy, Place, Box 1188, New York, NY, 10029-6574, USA.
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13
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Reed WR, Little JW, Lima CR, Sorge RE, Yarar-Fisher C, Eraslan M, Hurt CP, Ness TJ, Gu JG, Martins DF, Li P. Spinal Mobilization Prevents NGF-Induced Trunk Mechanical Hyperalgesia and Attenuates Expression of CGRP. Front Neurosci 2020; 14:385. [PMID: 32425750 PMCID: PMC7204433 DOI: 10.3389/fnins.2020.00385] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/31/2019] [Accepted: 03/30/2020] [Indexed: 12/15/2022] Open
Abstract
Introduction Low back pain (LBP) is a complex and growing global health problem in need of more effective pain management strategies. Spinal mobilization (SM) is a non-pharmacological approach recommended by most clinical guidelines for LBP, but greater utilization and treatment optimization are hampered by a lack of mechanistic knowledge underlying its hypoalgesic clinical effects. Methods Groups of female Sprague-Dawley rats received unilateral trunk (L5 vertebral level) injections (50 μl) of either vehicle (phosphate-buffer solution, PBS; VEH) or nerve growth factor (NGF; 0.8 μM) on Days 0 and 5 with or without daily L5 SM (VEH, NGF, VEH + SM, VEH + SM). Daily passive SM (10 min) was delivered by a feedback motor (1.2 Hz, 0.9N) from Days 1 to 12. Changes in pain assays were determined for mechanical and thermal reflexive behavior, exploratory behavior (open field events) and spontaneous pain behavior (rat grimace scale). On Day 12, lumbar (L1–L6) dorsal root ganglia (DRG) were harvested bilaterally and calcitonin gene-related peptide (CGRP) positive immunoreactive neurons were quantified from 3 animals (1 DRG tissue section per segmental level) per experimental group. Results NGF induced bilateral trunk (left P = 0.006, right P = 0.001) mechanical hyperalgesia and unilateral hindpaw allodynia (P = 0.006) compared to the vehicle group by Day 12. Additionally, we found for the first time that NGF animals demonstrated decreased exploratory behaviors (total distance traveled) and increased grimace scale scoring compared to the VEH group. Passive SM prevented this development of local (trunk) mechanical hyperalgesia and distant (hindpaw) allodynia, and normalized grimace scale scores. NGF increased CGRP positive immunoreactive neurons in ipsilateral lumbar DRGs compared to the VEH group ([L1]P = 0.02; [L2]P = 0.007) and SM effectively negated this increase in pain-related neuropeptide CGRP expression. Conclusion SM prevents the development of local (trunk) NGF-induced mechanical hyperalgesia and distant (hindpaw) allodynia, in part, through attenuation of CGRP expression in lumbar DRG sensory neurons. NGF decreases rat exploratory behavior and increases spontaneous pain for which passive SM acts to mitigate these pain-related behavioral changes. These initial study findings suggest that beginning daily SM soon after injury onset might act to minimize or prevent the development of LBP by reducing production of pain-related neuropeptides.
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Affiliation(s)
- William R Reed
- Department of Physical Therapy, University of Alabama at Birmingham, Birmingham, AL, United States.,Rehabilitation Sciences Program, University of Alabama at Birmingham, Birmingham, AL, United States
| | - Joshua W Little
- Department of Surgery, Center for Anatomical Science and Education, Saint Louis University School of Medicine, St. Louis, MO, United States
| | - Carla R Lima
- Rehabilitation Sciences Program, University of Alabama at Birmingham, Birmingham, AL, United States
| | - Robert E Sorge
- Department of Psychology, University of Alabama at Birmingham, Birmingham, AL, United States
| | - Ceren Yarar-Fisher
- Department of Physical Medicine and Rehabilitation, University of Alabama at Birmingham, Birmingham, AL, United States
| | - Mualla Eraslan
- Department of Physical Medicine and Rehabilitation, University of Alabama at Birmingham, Birmingham, AL, United States
| | - Christopher P Hurt
- Department of Physical Therapy, University of Alabama at Birmingham, Birmingham, AL, United States.,Rehabilitation Sciences Program, University of Alabama at Birmingham, Birmingham, AL, United States
| | - Timothy J Ness
- Department of Anesthesiology and Perioperative Medicine, University of Alabama at Birmingham, Birmingham, AL, United States
| | - Jianguo G Gu
- Department of Anesthesiology and Perioperative Medicine, University of Alabama at Birmingham, Birmingham, AL, United States
| | - Daniel F Martins
- Postgraduate Program in Health Sciences, Experimental Neuroscience Laboratory (LaNEx), University of Southern Santa Catarina, Palhoça, Brazil
| | - Peng Li
- School of Nursing, University of Alabama at Birmingham, Birmingham, AL, United States
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14
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Lai A, Ho L, Evashwick-Rogler TW, Watanabe H, Salandra J, Winkelstein BA, Laudier D, Hecht AC, Pasinetti GM, Iatridis JC. Dietary polyphenols as a safe and novel intervention for modulating pain associated with intervertebral disc degeneration in an in-vivo rat model. PLoS One 2019; 14:e0223435. [PMID: 31577822 PMCID: PMC6774529 DOI: 10.1371/journal.pone.0223435] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/27/2019] [Accepted: 09/21/2019] [Indexed: 01/08/2023] Open
Abstract
Developing effective therapies for back pain associated with intervertebral disc (IVD) degeneration is a research priority since it is a major socioeconomic burden and current conservative and surgical treatments have limited success. Polyphenols are naturally occurring compounds in plant-derived foods and beverages, and evidence suggests dietary supplementation with select polyphenol preparations can modulate diverse neurological and painful disorders. This study tested whether supplementation with a select standardized Bioactive-Dietary-Polyphenol-Preparation (BDPP) may alleviate pain symptoms associated with IVD degeneration. Painful IVD degeneration was surgically induced in skeletally-mature rats by intradiscal saline injection into three consecutive lumbar IVDs. Injured rats were given normal or BDPP-supplemented drinking water. In-vivo hindpaw mechanical allodynia and IVD height were assessed weekly for 6 weeks following injury. Spinal column, dorsal-root-ganglion (DRG) and serum were collected at 1 and 6 weeks post-operative (post-op) for analyses of IVD-related mechanical and biological pathogenic processes. Dietary BDPP significantly alleviated the typical behavioral sensitivity associated with surgical procedures and IVD degeneration, but did not modulate IVD degeneration nor changes of pro-inflammatory cytokine levels in IVD. Gene expression analyses suggested BDPP might have an immunomodulatory effect in attenuating the expression of pro-inflammatory cytokines in DRGs. This study supports the idea that dietary supplementation with BDPP has potential to alleviate IVD degeneration-related pain, and further investigations are warranted to identify the mechanisms of action of dietary BDPP.
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Affiliation(s)
- Alon Lai
- Leni & Peter W. May Department of Orthopaedics, Icahn School of Medicine at Mount Sinai, New York, New York, United States of America
| | - Lap Ho
- Department of Neurology, Icahn School of Medicine at Mount Sinai, New York, New York, United States of America
- James J. Peters Veterans Affairs Medical Center, Bronx, New York, United States of America
| | - Thomas W. Evashwick-Rogler
- Leni & Peter W. May Department of Orthopaedics, Icahn School of Medicine at Mount Sinai, New York, New York, United States of America
| | | | - Jonathan Salandra
- Philadelphia College of Osteopathic Medicine, Philadelphia, Pennsylvania, United States of America
| | - Beth A. Winkelstein
- Department of Bioengineering, University of Pennsylvania, Philadelphia, Pennsylvania, United States of America
| | - Damien Laudier
- Leni & Peter W. May Department of Orthopaedics, Icahn School of Medicine at Mount Sinai, New York, New York, United States of America
| | - Andrew C. Hecht
- Leni & Peter W. May Department of Orthopaedics, Icahn School of Medicine at Mount Sinai, New York, New York, United States of America
| | - Giulio M. Pasinetti
- Department of Neurology, Icahn School of Medicine at Mount Sinai, New York, New York, United States of America
- James J. Peters Veterans Affairs Medical Center, Bronx, New York, United States of America
| | - James C. Iatridis
- Leni & Peter W. May Department of Orthopaedics, Icahn School of Medicine at Mount Sinai, New York, New York, United States of America
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15
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Abstract
CGRP has long been suspected as a mediator of arthritis pain, although evidence that CGRP directly mediates human musculoskeletal pain remains circumstantial. This chapter describes in depth the evidence surrounding CGRP's association with pain in musculoskeletal disorders and also summarises evidence for CGRP being a direct cause of pain in other conditions. CGRP-immunoreactive nerves are present in musculoskeletal tissues, and CGRP expression is altered in musculoskeletal pain. CGRP modulates musculoskeletal pain through actions both in the periphery and central nervous system. Human observational studies, research on animal arthritis models and the few reported randomised controlled trials in humans of treatments that target CGRP provide the context of CGRP as a possible pain biomarker or mediator in conditions other than migraine.
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Affiliation(s)
- David A Walsh
- Pain Centre Versus Arthritis, NIHR Nottingham Biomedical Research Centre and Division of ROD, University of Nottingham, Nottingham, UK.
- Rheumatology, Sherwood Forest Hospitals NHS Foundation Trust, Nottinghamshire, UK.
| | - Daniel F McWilliams
- Pain Centre Versus Arthritis, NIHR Nottingham Biomedical Research Centre and Division of ROD, University of Nottingham, Nottingham, UK
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16
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Yang G, Chen L, Gao Z, Wang Y. Implication of microglia activation and CSF-1/CSF-1Rpathway in lumbar disc degeneration-related back pain. Mol Pain 2018; 14:1744806918811238. [PMID: 30326776 PMCID: PMC6243401 DOI: 10.1177/1744806918811238] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/19/2022] Open
Abstract
Back pain is common and costly. Although lumbar disc degeneration has long been regarded as a major contributor to back pain, how disc degeneration leads to back pain remains unclear. Recent studies observed microglia activation in the spinal cord after disc degeneration, suggesting activated microglia may be involved in discogenic back pain. To determine whether microglia activation participates in disc degeneration-induced back pain, we used a modified disc puncture-induced degeneration-related back pain mouse model to examine the changes in spinal microglia and investigate the potential link between microglia activation and discogenic back pain. In this study, 46 CX3CR1GFP/+ male mice were used in experimental and sham groups. A modified posterolateral retroperitoneal approach was used to expose the L3/L4 disc to induce the needle puncture in the experimental group. Behavioral tests, including grip force and physical function, were used to measure back pain at pre- and postsurgery. The L3 dorsal root ganglions and lumbar spinal cord were obtained at postoperative weeks 1 to 4 followed by immunofluorescence with different antibodies. Micrographs were obtained by confocal microscopy, and morphometric measurements of microglia were analyzed using Imaris. The punctured disc underwent progressive degeneration and mice with disc degeneration showed impaired grip force and physical function. Compared to the control mice, the number of microglia in the lumbar spinal cord was significantly increased in the disc-punctured animals. Moreover, accumulated microglia exhibited larger soma size and lesser ramification in the disc-injured mice. Immunofluorescence demonstrated colony-stimulating factor 1, a cytokine that promotes microglia repopulation, was significantly increased in L3 dorsal root ganglions, whereas its receptor colony-stimulating factor 1 receptor was upregulated on microglia in the disc-injured mice. In summary, lumbar disc puncture caused progressive disc degeneration which induced microglia activation and back pain in mice. Increased colony-stimulating factor 1/colony-stimulating factor 1 receptor signaling is involved in the disc degeneration-induced microglia activation and back pain.
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Affiliation(s)
- Ge Yang
- 1 Spine Lab, Department of Orthopedic Surgery, the First Affiliated Hospital, Zhejiang University School of Medicine, Hangzhou, China
| | - Lunhao Chen
- 1 Spine Lab, Department of Orthopedic Surgery, the First Affiliated Hospital, Zhejiang University School of Medicine, Hangzhou, China
| | - Zhihua Gao
- 2 Department of Neurobiology, Institute of Neuroscience, National Health Commission and Chinese Academy of Medical Sciences Key Laboratory of Medical Neurobiology, Zhejiang University School of Medicine, Hangzhou, China
| | - Yue Wang
- 1 Spine Lab, Department of Orthopedic Surgery, the First Affiliated Hospital, Zhejiang University School of Medicine, Hangzhou, China
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17
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Shi C, Das V, Li X, Kc R, Qiu S, O-Sullivan I, Ripper RL, Kroin JS, Mwale F, Wallace AA, Zhu B, Zhao L, van Wijnen AJ, Ji M, Lu J, Votta-Velis G, Yuan W, Im HJ. Development of an in vivo mouse model of discogenic low back pain. J Cell Physiol 2018; 233:6589-6602. [PMID: 29150945 DOI: 10.1002/jcp.26280] [Citation(s) in RCA: 24] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/19/2017] [Accepted: 11/14/2017] [Indexed: 11/09/2022]
Abstract
Discogenic low back pain (DLBP) is extremely common and costly. Effective treatments are lacking due to DLBP's unknown pathogenesis. Currently, there are no in vivo mouse models of DLBP, which restricts research in this field. The aim of this study was to establish a reliable DLBP model in mouse that captures the pathological changes in the disc and allows longitudinal pain testing. The model was generated by puncturing the mouse lumbar discs (L4/5, L5/6, and L6/S1) and removing the nucleus pulposus using a microscalpel under the microscope. Histology, molecular pathways, and pain-related behaviors were examined. Over 12 weeks post-surgery, animals displayed the mechanical, heat, and cold hyperalgesia along with decreased burrowing and rearing. Histology showed progressive disc degeneration with loss of disc height, nucleus pulposus reduction, proteoglycan depletion, and annular fibrotic disorganization. Immunohistochemistry revealed a substantial increase in inflammatory mediators at 2 and 4 weeks. Nerve growth factor was upregulated from 2 weeks to the end of the experiment. Nerve fiber ingrowth was induced in the injured discs after 4 weeks. Disc-puncture also produced an upregulation of neuropeptides in dorsal root ganglia neurons and an activation of glial cells in the spinal cord dorsal horn. These findings indicate that the cellular and structural changes in discs, as well as peripheral and central nervous system plasticity, paralleled persistent, and robust behavioral pain responses. Therefore, this mouse DLBP model could be used to investigate mechanisms underlying discogenic pain, thereby facilitating effective drug screening and development of treatments for DLBP.
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Affiliation(s)
- Changgui Shi
- Department of Orthopedic Surgery, Changzheng Hospital, Second Military Medical University, Shanghai, China
- Department of Biochemistry, Rush University Medical Center, Chicago, Illinois
| | - Vaskar Das
- Department of Biochemistry, Rush University Medical Center, Chicago, Illinois
| | - Xin Li
- Department of Biochemistry, Rush University Medical Center, Chicago, Illinois
| | - Ranjan Kc
- Department of Biochemistry, Rush University Medical Center, Chicago, Illinois
| | - Sujun Qiu
- Department of Biochemistry, Rush University Medical Center, Chicago, Illinois
- Department of Orthopedic Surgery, Zhujiang Hospital, Southern Medical University, Guangzhou, China
| | - InSug O-Sullivan
- Department of Internal Medicine, The University of Illinois at Chicago (UIC), Chicago, Illinois
| | - Richard L Ripper
- Department of Anesthesiology, The University of Illinois at Chicago (UIC), Chicago, Illinois
| | - Jeffrey S Kroin
- Department of Anesthesiology, Rush University Medical Center, Chicago, Illinois
| | - Fackson Mwale
- Department of Surgery, McGill University and Orthopaedic Research Laboratory, Lady Davis Institute for Medical Research, SMBD-Jewish General Hospital, Montreal, Canada
| | - Atiyayein A Wallace
- Department of Biochemistry, Rush University Medical Center, Chicago, Illinois
| | - Bingqian Zhu
- Department of Biobehavioral Health Science, The University of Illinois at Chicago (UIC), Chicago, Illinois
| | - Lan Zhao
- Department of Biochemistry, Rush University Medical Center, Chicago, Illinois
| | | | - Mingliang Ji
- Department of Orthopaedic Surgery, Southeast University Zhongda Hospital, Nanjing, China
| | - Jun Lu
- Department of Orthopaedic Surgery, Southeast University Zhongda Hospital, Nanjing, China
| | - Gina Votta-Velis
- Department of Anesthesiology, The University of Illinois at Chicago (UIC), Chicago, Illinois
- Jesse Brown Veterans Affairs Medical Center (JBVAMC), Chicago, Illinois
| | - Wen Yuan
- Department of Orthopedic Surgery, Changzheng Hospital, Second Military Medical University, Shanghai, China
| | - Hee-Jeong Im
- Department of Biochemistry, Rush University Medical Center, Chicago, Illinois
- Jesse Brown Veterans Affairs Medical Center (JBVAMC), Chicago, Illinois
- Department of Bioengineering, The University of Illinois at Chicago (UIC), Chicago, Illinois
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18
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Evashwick-Rogler TW, Lai A, Watanabe H, Salandra JM, Winkelstein BA, Cho SK, Hecht AC, Iatridis JC. Inhibiting tumor necrosis factor-alpha at time of induced intervertebral disc injury limits long-term pain and degeneration in a rat model. JOR Spine 2018; 1. [PMID: 29963655 PMCID: PMC6022768 DOI: 10.1002/jsp2.1014] [Citation(s) in RCA: 44] [Impact Index Per Article: 7.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/28/2022] Open
Abstract
Background Painful intervertebral disc (IVD) degeneration has tremendous societal costs and few effective therapies. Intradiscal tumor necrosis factor‐alpha (TNFα) is commonly associated with low back pain, but the direct relationship remains unclear. Purpose Treatment strategies for low back pain require improved understanding of the complex relationships between pain, intradiscal pro‐inflammatory cytokines, and structural IVD degeneration. A rat in vivo lumbar IVD puncture model was used to 1) determine the role of TNFα in initiating painful IVD degeneration, and 2) identify statistical relationships between painful behavior, IVD degeneration, and intradiscal pro‐inflammatory cytokine expression. Methods Lumbar IVDs were punctured anteriorly and injected with TNFα, anti‐TNFα, or saline and compared with sham and naive controls. Hindpaw mechanical hyperalgesia was assayed weekly to determine pain over time. 6‐weeks post‐surgery, animals were sacrificed, and IVD degeneration, IVD height, and intradiscal TNFα and interleukin‐1 beta (IL‐1β) expressions were assayed. Results Intradiscal TNFα injection increased pain and IVD degeneration whereas anti‐TNFα alleviated pain to sham level. Multivariate step‐wise linear regression identified pain threshold was predicted by IVD degeneration and intradiscal TNFα expression. Pain threshold was also linearly associated with IVD height loss and IL‐1β. Discussion The significant associations between IVD degeneration, height loss, inflammation, and painful behavior highlight the multifactorial nature of painful IVD degeneration and the challenges to diagnose and treat a specific underlying factor. We concluded that TNFα is an initiator of painful IVD degeneration and its early inhibition can mitigate pain and degeneration. Intradiscal TNFα inhibition following IVD injury may warrant investigation for its potential to alter downstream painful IVD degeneration processes.
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Affiliation(s)
- Thomas W Evashwick-Rogler
- Leni and Peter W. May Department of Orthopaedics, Icahn School of Medicine at Mount Sinai, New York, New York
| | - Alon Lai
- Leni and Peter W. May Department of Orthopaedics, Icahn School of Medicine at Mount Sinai, New York, New York
| | - Hironobu Watanabe
- Leni and Peter W. May Department of Orthopaedics, Icahn School of Medicine at Mount Sinai, New York, New York.,Keiyu Spine Center, Keiyu Orthopedic Hospital, Tatebayashi, Japan
| | - Jonathan M Salandra
- Leni and Peter W. May Department of Orthopaedics, Icahn School of Medicine at Mount Sinai, New York, New York
| | - Beth A Winkelstein
- Departments of Bioengineering and Neurosurgery, University of Pennsylvania, Philadelphia, Pennsylvania
| | - Samuel K Cho
- Leni and Peter W. May Department of Orthopaedics, Icahn School of Medicine at Mount Sinai, New York, New York
| | - Andrew C Hecht
- Leni and Peter W. May Department of Orthopaedics, Icahn School of Medicine at Mount Sinai, New York, New York
| | - James C Iatridis
- Leni and Peter W. May Department of Orthopaedics, Icahn School of Medicine at Mount Sinai, New York, New York
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19
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Shi C, Qiu S, Riester SM, Das V, Zhu B, Wallace AA, van Wijnen AJ, Mwale F, Iatridis JC, Sakai D, Votta-Velis G, Yuan W, Im HJ. Animal models for studying the etiology and treatment of low back pain. J Orthop Res 2018; 36:1305-1312. [PMID: 28921656 PMCID: PMC6287742 DOI: 10.1002/jor.23741] [Citation(s) in RCA: 38] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 06/06/2017] [Accepted: 09/13/2017] [Indexed: 02/04/2023]
Abstract
Chronic low back pain is a major cause of disability and health care costs. Effective treatments are inadequate for many patients. Animal models are essential to further understanding of the pain mechanism and testing potential therapies. Currently, a number of preclinical models have been developed attempting to mimic aspects of clinical conditions that contribute to low back pain (LBP). This review focused on describing these animal models and the main behavioral tests for assessing pain in each model. Animal models of LBP can be divided into the following five categories: Discogenic LBP, radicular back pain, facet joint osteoarthritis back pain, muscle-induced LBP, and spontaneous occurring LBP models. These models are important not only for enhancing our knowledge of how LBP is generated, but also for the development of novel therapeutic regimens to treat LBP in patients. © 2017 Orthopaedic Research Society. Published by Wiley Periodicals, Inc. J Orthop Res 36:1305-1312, 2018.
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Affiliation(s)
- Changgui Shi
- Department of Orthopedic Surgery, Changzheng Hospital,
Second Military Medical University of China, Shanghai, China
| | - Sujun Qiu
- Department of Orthopedic Surgery, Zhujiang Hospital,
Southern Medical University, Guangzhou, China
| | - Scott M. Riester
- Department of Orthopedic Surgery, Mayo Clinic, Rochester,
Minnesota
| | - Vaskar Das
- Department of Biochemistry, Rush University Medical Center,
Chicago, Illinois
| | - Bingqian Zhu
- Departments of Biobehavioral Health Science, University of
Illinois at Chicago (UIC), Chicago, Illinois
| | | | | | - Fackson Mwale
- Department of Surgery, McGill University and Orthopaedic
Research Laboratory, Lady Davis Institute for Medical Research, SMBD-Jewish General
Hospital, Montreal, Canada
| | - James C. Iatridis
- Leni & Peter May Department of Orthopaedics, Icahn
School of Medicine at Mount Sinai, New York, New York
| | - Daisuke Sakai
- Department of Orthopaedic Surgery, Tokai University School
of Medicine, Kanagawa, Japan
| | - Gina Votta-Velis
- Department of Anesthesiology, University of Illinois at
Chicago (UIC), Chicago, Illinois,,Jesse Brown Veterans Affairs Medical Center (JBVAMC) at
Chicago, Chicago, Illinois
| | - Wen Yuan
- Department of Orthopedic Surgery, Changzheng Hospital,
Second Military Medical University of China, Shanghai, China
| | - Hee-Jeong Im
- Jesse Brown Veterans Affairs Medical Center (JBVAMC) at
Chicago, Chicago, Illinois,,Department of Bioengineering, University of Illinois at
Chicago (UIC), Chicago, Illinois
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20
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Fazzari J, Linher-Melville K, Singh G. Tumour-Derived Glutamate: Linking Aberrant Cancer Cell Metabolism to Peripheral Sensory Pain Pathways. Curr Neuropharmacol 2018; 15:620-636. [PMID: 27157265 PMCID: PMC5543678 DOI: 10.2174/1570159x14666160509123042] [Citation(s) in RCA: 13] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/18/2016] [Revised: 03/16/2016] [Accepted: 04/17/2016] [Indexed: 01/22/2023] Open
Abstract
Background Chronic pain is a major symptom that develops in cancer patients, most commonly emerging during advanced stages of the disease. The nature of cancer-induced pain is complex, and the efficacy of current therapeutic interventions is restricted by the dose-limiting side-effects that accompany common centrally targeted analgesics. Methods This review focuses on how up-regulated glutamate production and export by the tumour converge at peripheral afferent nerve terminals to transmit nociceptive signals through the transient receptor cation channel, TRPV1, thereby initiating central sensitization in response to peripheral disease-mediated stimuli. Results Cancer cells undergo numerous metabolic changes that include increased glutamine catabolism and over-expression of enzymes involved in glutaminolysis, including glutaminase. This mitochondrial enzyme mediates glutaminolysis, producing large pools of intracellular glutamate. Up-regulation of the plasma membrane cystine/glutamate antiporter, system xc-, promotes aberrant glutamate release from cancer cells. Increased levels of extracellular glutamate have been associated with the progression of cancer-induced pain and we discuss how this can be mediated by activation of TRPV1. Conclusion With a growing population of patients receiving inadequate treatment for intractable pain, new targets need to be considered to better address this largely unmet clinical need for improving their quality of life. A better understanding of the mechanisms that underlie the unique qualities of cancer pain will help to identify novel targets that are able to limit the initiation of pain from a peripheral source–the tumour.
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Affiliation(s)
| | | | - Gurmit Singh
- Department of Pathology and Molecular Medicine; Michael G. DeGroote Institute for Pain Research and Care, McMaster University, Hamilton, ON. Canada
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Mosley GE, Evashwick-Rogler TW, Lai A, Iatridis JC. Looking beyond the intervertebral disc: the need for behavioral assays in models of discogenic pain. Ann N Y Acad Sci 2017; 1409:51-66. [PMID: 28797134 DOI: 10.1111/nyas.13429] [Citation(s) in RCA: 39] [Impact Index Per Article: 5.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/21/2017] [Revised: 06/02/2017] [Accepted: 06/12/2017] [Indexed: 12/28/2022]
Abstract
Orthopedic research into chronic discogenic back pain has commonly focused on aging- and degeneration-related changes in intervertebral disc structure, biomechanics, and biology. However, the primary spine-related reason for physician office visits is pain. The ambiguous nature of the human condition of discogenic low back pain motivates the use of animal models to better understand the pathophysiology. Discogenic back pain models must consider both emergent behavioral changes following pain induction and changes in the nervous system that mediate such behavior. Looking beyond the intervertebral disc, we describe the different ways to classify pain in human patients and animal models. We describe several behavioral assays that can be used in rodent models to augment disc degeneration measurements and characterize different types of pain. We review rodent models of discogenic pain that employed behavioral pain assays and highlight a need to better integrate neuroscience and orthopedic science methods to extend current understanding of the complex and multifactorial pathophysiology of discogenic back pain.
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Affiliation(s)
- Grace E Mosley
- Leni and Peter W. May Department of Orthopaedics, Icahn School of Medicine at Mount Sinai, New York, New York
| | - Thomas W Evashwick-Rogler
- Leni and Peter W. May Department of Orthopaedics, Icahn School of Medicine at Mount Sinai, New York, New York
| | - Alon Lai
- Leni and Peter W. May Department of Orthopaedics, Icahn School of Medicine at Mount Sinai, New York, New York
| | - James C Iatridis
- Leni and Peter W. May Department of Orthopaedics, Icahn School of Medicine at Mount Sinai, New York, New York
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22
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Jin L, Balian G, Li XJ. Animal models for disc degeneration-an update. Histol Histopathol 2017; 33:543-554. [PMID: 28580566 DOI: 10.14670/hh-11-910] [Citation(s) in RCA: 24] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/06/2023]
Abstract
Intervertebral disc degeneration is considered a major cause of back pain that places a heavy burden on society, both because of its effect on the physiology of individuals and its consequences on the world economy. During the past few decades, research findings in the pre-clinical setting have led to a significant increase in the understanding of intervertebral disc degeneration, although many aspects of the disease remain unclear. The goal of this review is to summarize existing animal models for disc degeneration studies and the difficulties that are associated with the use of such models. A firm understanding of the cellular and molecular events that ensue as a result of injuries, as well as environmental factors, could be instrumental in the development of targeted therapies for the treatment of intervertebral disc degeneration.
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Affiliation(s)
- Li Jin
- Department of Orthopaedic Surgery, University of Virginia, Charlottesville, VA, USA
| | - Gary Balian
- Department of Orthopaedic Surgery, University of Virginia, Charlottesville, VA, USA
| | - Xudong Joshua Li
- Department of Orthopaedic Surgery, University of Virginia, Charlottesville, VA, USA.
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Lai A, Moon A, Purmessur D, Skovrlj B, Laudier DM, Winkelstein BA, Cho SK, Hecht AC, Iatridis JC. Annular puncture with tumor necrosis factor-alpha injection enhances painful behavior with disc degeneration in vivo. Spine J 2016; 16:420-31. [PMID: 26610672 PMCID: PMC4913353 DOI: 10.1016/j.spinee.2015.11.019] [Citation(s) in RCA: 60] [Impact Index Per Article: 7.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 02/13/2015] [Revised: 10/01/2015] [Accepted: 11/10/2015] [Indexed: 02/03/2023]
Abstract
BACKGROUND CONTEXT Painfulintervertebral disc degeneration is extremely common and costly. Effective treatments are lacking because the nature of discogenic pain is complex with limited capacity to distinguish painful conditions from age-related changes in the spine. Hypothesized sources of discogenic pain include chronic inflammation, neurovascular ingrowth, and structural disruption. PURPOSE This study aimed to investigate inflammation, pro-neurovascular growth factors, and structural disruption as sources of painful disc degeneration STUDY DESIGN/SETTING This study used an in vivo study to address these hypothesized mechanisms with anterior intradiscal injections of tumor necrosis factor-alpha (TNFα), pro-neurovascular growth factors: nerve growth factor and vascular endothelial growth factor (NGF and VEGF), and saline with additional sham surgery and naïve controls. Depth of annular puncture was also evaluated for its effects on structural and painful degeneration. METHODS Rat lumbar discs were punctured (shallow or deeper puncture) and intradiscally injected with saline, TNFα, or NGF and VEGF. Structural disc degeneration was assessed using X-ray, magnetic resonance imaging (MRI), and histology. The rat painful condition was evaluated using Von Frey hyperalgesia measurements, and substance P immunostaining in dorsal root ganglion (DRG) was performed to determine the source of pain. RESULTS Saline injection increased painful responses with degenerative changes in disc height, MRI intensity, and morphologies of disc structure and cell. TNFα and NGF/VEGF accelerated painful behavior, and TNFα-injected animals had increased substance P in DRGs. Deeper punctures led to more severe disc degeneration. Multiple regression analysis showed that the painful behavior was correlated with disc height loss. CONCLUSIONS We concluded that rate and severity of structural disc degeneration was associated with the amount of annular disruption and puncture depth. The painful behavior was associated with disc height loss and discal inflammatory state, whereas pro-inflammatory cytokines might play a more important role in the level of pain, which might have resulted from enhanced DRG sensitization. These in vivo painful disc degeneration models with different severities of structural changes may be useful for investigating discogenic pain mechanisms and for screening therapies, although interpretations must note the differences between all surgically induced animal models and the human condition.
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Affiliation(s)
- Alon Lai
- Icahn School of Medicine at Mount Sinai, 1 Gustave Levy Place, Box 1188, Orthopaedics, New York, NY 10029-6574
| | - Andrew Moon
- Icahn School of Medicine at Mount Sinai, 1 Gustave Levy Place, Box 1188, Orthopaedics, New York, NY 10029-6574
| | - Devina Purmessur
- Icahn School of Medicine at Mount Sinai, 1 Gustave Levy Place, Box 1188, Orthopaedics, New York, NY 10029-6574,The Ohio State University, Dorothy Davis Heart and Lung Research Institute, 473 W 12th Avenue, Room 012L, Columbus OH 43210
| | | | - Damien M. Laudier
- Icahn School of Medicine at Mount Sinai, 1 Gustave Levy Place, Box 1188, Orthopaedics, New York, NY 10029-6574
| | | | - Samuel K. Cho
- Icahn School of Medicine at Mount Sinai, 1 Gustave Levy Place, Box 1188, Orthopaedics, New York, NY 10029-6574
| | - Andrew C. Hecht
- Icahn School of Medicine at Mount Sinai, 1 Gustave Levy Place, Box 1188, Orthopaedics, New York, NY 10029-6574
| | - James C. Iatridis
- Icahn School of Medicine at Mount Sinai, 1 Gustave Levy Place, Box 1188, Orthopaedics, New York, NY 10029-6574,Corresponding author. Icahn School of Medicine at Mount Sinai, 1 Gustave Levy Place, Box 1188, Orthopaedics, New York, NY 10029-6574, USA. Tel.: 212 241 1517; fax: 212 876 3168. (J.C. Iatridis)
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Lai A, Moon A, Purmessur D, Skovrlj B, Winkelstein BA, Cho SK, Hecht AC, Iatridis JC. Assessment of functional and behavioral changes sensitive to painful disc degeneration. J Orthop Res 2015; 33:755-64. [PMID: 25731955 PMCID: PMC4406864 DOI: 10.1002/jor.22833] [Citation(s) in RCA: 50] [Impact Index Per Article: 5.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 09/10/2014] [Accepted: 01/15/2015] [Indexed: 02/04/2023]
Abstract
The development of an in vivo rodent discogenic pain model can provide insight into mechanisms for painful disc degeneration. Painful disc degeneration in rodents can be inferred by examining responses to external stimuli, observing pain-related behaviors, and measuring functional performance. This study compared the sensitivity of multiple pain and functional assessment methods to disc disruption for identifying the parameters sensitive to painful disc degeneration in rats. Disc degeneration was induced in rats by annular injury with saline injection. The severity of disc degeneration, pain sensitivity, and functional performance were compared to sham and naïve control rats. Saline injection induced disc degeneration with decreased disc height and MRI signal intensity as well as more fibrous nucleus pulposus, disorganized annular lamellae and decreased proteoglycan. Rats also demonstrated increased painful behaviors including decreased hindpaw mechanical and thermal sensitivities, increased grooming, and altered gait patterns with hindpaw mechanical hyperalgesia and duration of grooming tests being most sensitive. This is the first study to compare sensitivities of different pain assessment methods in an in vivo rat model of disc degeneration. Hindpaw mechanical sensitivity and duration of grooming were the most sensitive parameters to surgically induced degenerative changes and overall results were suggestive of disc degeneration associated pain.
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Affiliation(s)
- Alon Lai
- Leni & Peter W May Department of Orthopedics, Icahn School of Medicine at Mount Sinai, New York, New York
| | - Andrew Moon
- Leni & Peter W May Department of Orthopedics, Icahn School of Medicine at Mount Sinai, New York, New York
| | - Devina Purmessur
- Leni & Peter W May Department of Orthopedics, Icahn School of Medicine at Mount Sinai, New York, New York
| | - Branko Skovrlj
- Department of Neurosurgery, Icahn School of Medicine at Mount Sinai, New York, New York
| | - Beth A. Winkelstein
- Department of Bioengineering, University of Pennsylvania, Philadelphia, Pennsylvania
| | - Samuel K. Cho
- Leni & Peter W May Department of Orthopedics, Icahn School of Medicine at Mount Sinai, New York, New York
| | - Andrew C. Hecht
- Leni & Peter W May Department of Orthopedics, Icahn School of Medicine at Mount Sinai, New York, New York
| | - James C. Iatridis
- Leni & Peter W May Department of Orthopedics, Icahn School of Medicine at Mount Sinai, New York, New York
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Luan S, Wan Q, Luo H, Li X, Ke S, Lin C, Wu Y, Wu S, Ma C. Running exercise alleviates pain and promotes cell proliferation in a rat model of intervertebral disc degeneration. Int J Mol Sci 2015; 16:2130-44. [PMID: 25607736 PMCID: PMC4307353 DOI: 10.3390/ijms16012130] [Citation(s) in RCA: 19] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/05/2014] [Accepted: 01/12/2015] [Indexed: 12/19/2022] Open
Abstract
Chronic low back pain accompanied by intervertebral disk degeneration is a common musculoskeletal disorder. Physical exercise, which is clinically recommended by international guidelines, has proven to be effective for degenerative disc disease (DDD) patients. However, the mechanism underlying the analgesic effects of physical exercise on DDD remains largely unclear. The results of the present study showed that mechanical withdrawal thresholds of bilateral hindpaw were significantly decreased beginning on day three after intradiscal complete Freund's adjuvant (CFA) injection and daily running exercise remarkably reduced allodynia in the CFA exercise group beginning at day 28 compared to the spontaneous recovery group (controls). The hindpaw withdrawal thresholds of the exercise group returned nearly to baseline at the end of experiment, but severe pain persisted in the control group. Histological examinations performed on day 70 revealed that running exercise restored the degenerative discs and increased the cell densities of the annulus fibrosus (AF) and nucleus pulposus (NP). Furthermore, immunofluorescence labeling revealed significantly higher numbers of 5-bromo-2-deoxyuridine (BrdU)-positive cells in the exercise group on days 28, 42, 56 and 70, which indicated more rapid proliferation compared to the control at the corresponding time points. Taken together, these results suggest that running exercise might alleviate the mechanical allodynia induced by intradiscal CFA injection via disc repair and cell proliferation, which provides new evidence for future clinical use.
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Affiliation(s)
- Shuo Luan
- Department of Rehabilitation Medicine, Sun Yat-sen Memorial Hospital, Sun Yat-sen University, Guangzhou 510120, China.
| | - Qing Wan
- Department of Rehabilitation Medicine, Sun Yat-sen Memorial Hospital, Sun Yat-sen University, Guangzhou 510120, China.
| | - Haijie Luo
- Department of Rehabilitation Medicine, Sun Yat-sen Memorial Hospital, Sun Yat-sen University, Guangzhou 510120, China.
| | - Xiao Li
- Department of Rehabilitation Medicine, Sun Yat-sen Memorial Hospital, Sun Yat-sen University, Guangzhou 510120, China.
| | - Songjian Ke
- Department of Rehabilitation Medicine, Sun Yat-sen Memorial Hospital, Sun Yat-sen University, Guangzhou 510120, China.
| | - Caina Lin
- Department of Rehabilitation Medicine, Sun Yat-sen Memorial Hospital, Sun Yat-sen University, Guangzhou 510120, China.
| | - Yuanyuan Wu
- Department of Rehabilitation Medicine, Sun Yat-sen Memorial Hospital, Sun Yat-sen University, Guangzhou 510120, China.
| | - Shaoling Wu
- Department of Rehabilitation Medicine, Sun Yat-sen Memorial Hospital, Sun Yat-sen University, Guangzhou 510120, China
| | - Chao Ma
- Department of Rehabilitation Medicine, Sun Yat-sen Memorial Hospital, Sun Yat-sen University, Guangzhou 510120, China.
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26
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ISSLS Prize winner: Increased innervation and sensory nervous system plasticity in a mouse model of low back pain due to intervertebral disc degeneration. Spine (Phila Pa 1976) 2014; 39:1345-54. [PMID: 24718079 DOI: 10.1097/brs.0000000000000334] [Citation(s) in RCA: 79] [Impact Index Per Article: 7.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 02/01/2023]
Abstract
STUDY DESIGN Immunohistochemical and behavioral study using the SPARC (secreted protein, acidic, rich in cysteine)-null mouse model of low back pain (LBP) associated with accelerated intervertebral disc (IVD) degeneration. OBJECTIVE To determine if behavioral signs of LBP in SPARC-null mice are accompanied by sensory nervous system plasticity. SUMMARY OF BACKGROUND DATA IVD pathology is a significant contributor to chronic LBP. In humans and rodents, decreased expression of SPARC is associated with IVD degeneration. We previously reported that SPARC-null mice exhibit age-dependent behavioral signs of chronic axial LBP and radiating leg pain. METHODS SPARC-null and age-matched control young, middle-aged, and old mice (1.5, 6, and 24 mo of age, respectively) were evaluated. Cutaneous hind paw sensitivity to cold, heat, and mechanical stimuli were evaluated as measures of radiating pain. The grip force and tail suspension assays were performed to evaluate axial LBP. Motor impairment was assessed using an accelerating rotarod. IVD innervation was identified by immunohistochemistry targeting the nerve fiber marker PGP9.5 and the sensory neuropeptide calcitonin gene-related peptide (CGRP). Sensory nervous system plasticity was evaluated by quantification of CGRP- and neuropeptide-Y-immunoreactivity (-ir) in dorsal root ganglia neurons and CGRP-ir, GFAP-ir (astrocyte marker), and Iba-1-ir (microglia marker) in the spinal cord. RESULTS SPARC-null mice developed hypersensitivity to cold, axial discomfort, age-dependent motor impairment, age-dependent increases in sensory innervation in and around the IVDs, age-dependent upregulation of CGRP and neuropeptide-Y in dorsal root ganglia, and age-dependent upregulation of CGRP, microglia, and astrocytes in the spinal cord dorsal horn. CONCLUSION Increased innervation of degenerating IVDs by sensory nerve fibers and the neuroplasticity in sensory neurons and spinal cord could contribute to the underlying pathobiology of chronic discogenic LBP. LEVEL OF EVIDENCE N/A.
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Inhibiting IκB kinase-β downregulates inflammatory cytokines in injured discs and neuropeptides in dorsal root ganglia innervating injured discs in rats. Spine (Phila Pa 1976) 2014; 39:1171-7. [PMID: 24825147 DOI: 10.1097/brs.0000000000000374] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 02/01/2023]
Abstract
STUDY DESIGN Quantitative and immunohistological analysis of the efficacy of an IκB kinase-β (IKKβ) inhibitor in an injured intervertebral disc (IVD) model. OBJECTIVE To elucidate the efficacy of an IKKβ inhibitor on inflammatory cytokine levels in injured IVDs or on neuropeptide levels in the dorsal root ganglia (DRG) neurons innervating injured IVDs in rats. SUMMARY OF BACKGROUND DATA Multiple studies have suggested that upregulation of inflammatory cytokines in damaged IVDs causes discogenic low back pain. The efficacy of blocking individual inflammatory cytokines is limited; however, inflammatory cytokine stimuli often require IKKβ to activate nuclear factor-k B. METHODS Sprague-Dawley rats were divided into 3 groups: sham, saline (disc-injury plus saline), and IKKβ (disc-injury plus anti-IKKβ). To induce injury, IVDs were repeatedly punctured.Experiment 1: Four, 7, and 14 days postinjury, coccygeal (Co) 5/6, Co6/7, and Co7/8 IVDs were resected and tumor necrosis factor-α, interleukin (IL)-1β, and IL-6 levels were quantified by enzyme-linked immunosorbent assay. Experiment 2: The neurotracer Fluoro-Gold was injected into injured L5-L6 IVDs and uninjured sham group IVDs to detect DRG neurons. One week postsurgery, L1-L6 DRGs were immunolabeled with the neuropeptide calcitonin gene-related peptide. The proportions of Fluoro-Gold-labeled calcitonin gene-related peptide-immunoreactive DRG neurons were assessed. RESULTS Experiment 1: IVD levels of tumor necrosis factor-α (through 2 wk), IL-1β (at 4 d), and IL-6 (at 4 d) were significantly higher in the saline group than in the sham group, and significantly lower in the IKKβ group than in the saline group (P < 0.05). Experiment 2: The percentage of calcitonin gene-related peptide-immunoreactive Fluoro-Gold-labeled DRG neurons was significantly higher in the saline group than in the sham group, and significantly lower in the IKKβ group than in the saline group (P < 0.05). CONCLUSION Injury-induced upregulation of inflammatory cytokines within IVDs and increased levels of neuropeptides within DRG neurons can be suppressed by inhibiting IKKβ. LEVEL OF EVIDENCE N/A.
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Liu Q, Cui Q, Li XJ, Jin L. The applications of buckminsterfullerene C60 and derivatives in orthopaedic research. Connect Tissue Res 2014; 55:71-9. [PMID: 24409811 PMCID: PMC4124742 DOI: 10.3109/03008207.2013.877894] [Citation(s) in RCA: 28] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 02/03/2023]
Abstract
Abstract Buckminsterfullerene C60 and derivatives have been extensively explored in biomedical research due to their unique structure and unparalleled physicochemical properties. C60 is characterized as a "free radical sponge" with an anti-oxidant efficacy several hundred-fold higher than conventional anti-oxidants. Also, the C60 core has a strong electron-attracting ability and numerous functional compounds with widely different properties can be added to this fullerene cage. This review focused on the applications of C60 and derivatives in orthopaedic research, such as the treatment of cartilage degeneration, bone destruction, intervertebral disc degeneration (IVDD), vertebral bone marrow disorder, radiculopathy, etc., as well as their toxicity in vitro and in vivo. We suggest that C60 and derivatives, especially the C60 cores coupled with functional groups presenting new biological and pharmacological activities, are advantageous in orthopaedic research and will be promising in clinical performance for musculoskeletal disorders treatment; however, the pharmacokinetics and toxicology of these agents as local/systemic administration need to be carefully determined.
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Affiliation(s)
| | | | | | - Li Jin
- Correspondence: Li Jin, Orthopedic Research Laboratories, Department of Orthopedic Surgery, University of Virginia School of Medicine, Box 800374, Charlottesville, VA 22908, USA. Tel: 434-982-4135. Fax: 434-982-1691.
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Li Z, Liu H, Yang H, Wang J, Wang H, Zhang K, Ding W, Zheng Z. Both expression of cytokines and posterior annulus fibrosus rupture are essential for pain behavior changes induced by degenerative intervertebral disc: An experimental study in rats. J Orthop Res 2014; 32:262-72. [PMID: 24115280 DOI: 10.1002/jor.22494] [Citation(s) in RCA: 54] [Impact Index Per Article: 5.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 05/12/2013] [Accepted: 08/29/2013] [Indexed: 02/04/2023]
Abstract
The aim of this study was to analyze the relationship between intervertebral disc degeneration and low back pain (LBP). Rat L4/5 disc degeneration model was established by annular puncture using a 0.4 mm needle anteriorly or posteriorly. In both anterior and posterior puncture models, magnetic resonance imaging (MRI) and histological analyses revealed marked disc degeneration 2 weeks after puncture. Cytokine expression was up-regulated in different level in nucleus pulposus (NP) from 3 days after puncture. Pain behavioral tests indicated that the anterior disc puncture did not induce pain behavior changes, whereas the posterior disc puncture resulted in mechanical allodynia from 1 day to 21 days after injury. Besides, cytokine expression was significantly increased in dorsal root ganglion (DRG) at 1 and 2 weeks after posterior puncture, but not after the anterior puncture. These findings indicate the NP of the degenerative disc expresses different levels of inflammatory cytokines, and posterior disc puncture produced mechanical allodynia. The expression phase of cytokines in the NP was accordance with mechanical hyperalgesia in the posterior disc puncture model. Both expression of cytokines and posterior annulus fibrosus (AF) rupture in degenerative intervertebral disc are essential for pain behavior changes.
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Affiliation(s)
- Zemin Li
- Department of Spine Surgery, The First Affiliated Hospital of Sun Yat-sen University, No.58 Zhongshan 2nd Road, Guangzhou, 510080, China
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Abstract
We studied the effects of Russian preparation of porcine calcitonin (Calcitrinum, 1 U/100 g) on the level of glucose and total calcium, glycogen concentration in the liver, and glucose consumption by the muscle and adipose tissues in vivo and in vitro. The basal level of insulin and secretion of insulin in the dynamics of glucose tolerance test were studied after treatment with calcitonin. In addition to hypocalcemic effect, this substance produced significant hyperglycemic effects, decreased glycogen amount in the liver, inhibited insulin-induced glucose consumption by muscular and adipose tissues in vivo and in vitro, slowed down insulin secretion during glucose load, and impaired glucose tolerance. Thus, calcitonin had contra-insular effects on glucose metabolism.
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Affiliation(s)
- S S Moisa
- State Scientific Center of the Russian Federation Institute for Biomedical Problems, Russian Academy of Sciences, Moscow, Russia.
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Liu Q, Jin L, Mahon BH, Chordia MD, Shen FH, Li X. Novel treatment of neuroinflammation against low back pain by soluble fullerol nanoparticles. Spine (Phila Pa 1976) 2013; 38:1443-51. [PMID: 23466506 PMCID: PMC3731423 DOI: 10.1097/brs.0b013e31828fc6b7] [Citation(s) in RCA: 25] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 02/01/2023]
Abstract
STUDY DESIGN An in vitro study to investigate the anti-inflammatory effects of fullerol on mouse dorsal root ganglia (DRG) under tumor necrosis factor (TNF)-α induction. OBJECTIVE To evaluate the potential of a free radical scavenger, fullerol nanoparticles, to prevent DRG tissue and neuron inflammatory responses under TNF-α induction in vitro. SUMMARY OF BACKGROUND DATA Low back pain is one of the most common reasons for clinician visits in Western societies. Symptomatic intervertebral disc degeneration is strongly implicated as a cause of low back pain, as it results in DRG inflammation. Increased production of reactive oxygen species (ROS) is associated with DRG inflammation. METHODS With or without fullerol treatment, DRG tissue and DRG neurons isolated from wild-type C3H/HeNCrl (Charles River Laboratories, Wilmington, MA) mice were cultured under TNF-α induction. The amount of intracellular ROS was measured with H2DCFDA (Life Technologies Corporation, Grand Island, NY) fluorescence staining. Cellular apoptosis was detected via terminal deoxynucleotidyl transferase dUTP nick-end labeling assay. The expression of inflammatory as well as antioxidative enzyme genes in neurons was analyzed by real-time polymerase chain reaction. In addition, inflammatory cytokine expression in DRG tissue was determined by immunofluorescence staining and enzyme-linked immunosorbent assay. RESULTS Fluorescence staining results indicated that TNF-α markedly increased the production of intracellular ROS and the number of apoptotic cells. Under fullerol treatment, cellular apoptosis was reduced along with concomitant suppression of ROS. The expression of inflammatory cytokines interleukin 1 β, interleukin 6, cyclooxygenase-2, and prostaglandin E2, was also inhibited by fullerol in a dose-dependent manner. Furthermore, fullerol-treated cells exhibited upregulation of antioxidative enzyme genes superoxide dismutase 2 and catalase. CONCLUSION The results obtained from this study clearly suggest that fullerol treatment suppresses the inflammatory responses of DRG and neurons, as well as cellular apoptosis by decreasing the level of ROS and potentially enhancing antioxidative enzyme gene expression. Therefore, fullerol has potential to serve as a novel therapeutic agent for low back pain treatment. LEVEL OF EVIDENCE N/A.
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Affiliation(s)
- Qihai Liu
- Department of Orthopedic Surgery, University of Virginia Health System, Charlottesville, Virginia, United States of America
| | - Li Jin
- Department of Orthopedic Surgery, University of Virginia Health System, Charlottesville, Virginia, United States of America
| | - Brian H. Mahon
- Department of Orthopedic Surgery, University of Virginia Health System, Charlottesville, Virginia, United States of America
| | - Mahendra D. Chordia
- Department of Orthopedic Surgery, University of Virginia Health System, Charlottesville, Virginia, United States of America
| | - Francis H. Shen
- Department of Orthopedic Surgery, University of Virginia Health System, Charlottesville, Virginia, United States of America
| | - Xudong Li
- Department of Orthopedic Surgery, University of Virginia Health System, Charlottesville, Virginia, United States of America
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ISSLS prize winner: disc dynamic compression in rats produces long-lasting increases in inflammatory mediators in discs and induces long-lasting nerve injury and regeneration of the afferent fibers innervating discs: a pathomechanism for chronic discogenic low back pain. Spine (Phila Pa 1976) 2012; 37:1810-8. [PMID: 22366969 DOI: 10.1097/brs.0b013e31824ffac6] [Citation(s) in RCA: 49] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 02/01/2023]
Abstract
STUDY DESIGN Animal model of intravertebral disc (IVD) degeneration. OBJECTIVE To examine production of inflammatory mediators in IVDs and neuropeptides in dorsal root ganglia (DRGs) in rat models of IVD compression and injury. SUMMARY OF BACKGROUND DATA Sensory nerve fibers in IVDs and inflammatory mediator responses have been verified in animal models of IVD injury. However, the IVD injury in animals incompletely models degenerated human IVDs causing discogenic low back pain, because human IVDs are also subject to compression. METHODS Experimental groups (controls, IVD injury, IVD compression, and their combination) of Sprague Dawley rats were prepared. Fluoro-Gold (FG; Fluorochrome, Denver, CO) was applied into coccygeal IVDs. Inflammatory mediators in IVDs, including nerve growth factor, tumor necrosis factor α, interleukin 1β, and interleukin 6, were quantified using enzyme-linked immunosorbent assays. DRGs were immunostained for calcitonin gene-related peptide, activating transcription factor 3, and growth-associated phosphoprotein 43. RESULTS The upregulation of inflammatory mediators was transient in the IVD injury group but delayed and long-lasting in the IVD compression group. When the IVD injury and compression were combined, the upregulation of inflammatory mediators was long-lasting through 8 weeks. The proportion of calcitonin gene-related peptide-immunoreactive neurons among Fluoro-Gold-labeled neurons remained significantly higher in the IVD injury, compression, and combination groups than in the controls. In contrast, increases in the proportions of activating transcription factor 3-immunoreactive or growth-associated phosphoprotein 43-immunoreactive neurons in the IVD injury group animals were transient but long-lasting in the compression and combination groups compared with controls. CONCLUSION Disc injury in rats produces persistent increases in neuropeptides in DRGs but only transient increases in inflammatory mediators in IVDs. On the contrary, disc compression in rats produces a long-lasting increase in inflammatory mediators in IVDs and neuropeptides in DRGs. Moreover, disc compression induces persistent nerve injury and regeneration of the afferent fibers innervating IVDs.
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Glutaminase immunoreactivity and enzyme activity is increased in the rat dorsal root ganglion following peripheral inflammation. PAIN RESEARCH AND TREATMENT 2011; 2012:414697. [PMID: 22229088 PMCID: PMC3250962 DOI: 10.1155/2012/414697] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 07/01/2011] [Revised: 08/29/2011] [Accepted: 09/08/2011] [Indexed: 01/16/2023]
Abstract
Following inflammation, primary sensory neurons in the dorsal root ganglion (DRG) alter the production of several proteins. Most DRG neurons are glutamatergic, using glutaminase as the enzyme for glutamate production, but little is known about glutaminase following inflammation. In the present study, adjuvant-induced arthritis (AIA) was produced in rats with complete Freund's adjuvant into the hindpaw. At 7 days of AIA, DRG were examined with glutaminase immunohistochemistry, Western blot immunoreactivity, and enzyme activity. Image analysis revealed that glutaminase was elevated most in small-sized neurons (21%) (P < 0.05). Western blot analysis revealed a 19% increase (P < 0.05) in total glutaminase and 21% in mitochondrial glutaminase (P < 0.05). Glutaminase enzyme activity was elevated 29% (P < 0.001) from 2.20 to 2.83 moles/kg/hr. Elevated glutaminase in primary sensory neurons could lead to increased glutamate production in spinal primary afferent terminals contributing to central sensitization or in the peripheral process contributing to peripheral sensitization.
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Disk injury in rats produces persistent increases in pain-related neuropeptides in dorsal root ganglia and spinal cord glia but only transient increases in inflammatory mediators: pathomechanism of chronic diskogenic low back pain. Spine (Phila Pa 1976) 2011; 36:2260-6. [PMID: 21228748 DOI: 10.1097/brs.0b013e31820e68c7] [Citation(s) in RCA: 67] [Impact Index Per Article: 5.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 02/01/2023]
Abstract
STUDY DESIGN Immunohistological analysis in an injured intervertebral disk (IVD) model. OBJECTIVE To elucidate and compare in rats the behavior of the sensory nervous system and inflammatory mediators in experimentally injured IVDs. SUMMARY OF BACKGROUND DATA Multiple human and animal studies have verified the presence of sensory nerve fibers in IVDs or investigated the behavior of inflammatory mediators in injured IVDs, but no in vivo study to date has examined the relationship between the 2. METHODS Eight-week-old female rats were used. In the disk-injured group, L5/L6 disks were injured with a 24-gauge needle; simultaneously, the neurotracer Fluoro-gold was injected into the L5/L6 IVD. The L5/L6 IVD dorsal root ganglia (DRGs) from the L1 to L6 levels, and the spinal cord was resected at several time points after surgery. Nerve growth factor, tumor necrosis factor (TNF)-α and interleukin (IL)-6 production in the IVDs were quantified using enzyme-linked immunosorbent assay. DRGs were immunostained for calcitonin gene-related peptide, and spinal cord sections were immunostained for ionized calcium-binding adaptor molecule-1 and glial fibrillary acidic protein. RESULTS Nerve growth factor, and TNF-α levels (through 1 week) and IL-6 levels (through 4 days) were significantly higher in the disk-injured group than in the noninjured group (P < 0.05). However, starting at 2 weeks (nerve growth factor and TNF-α) or 1 week (IL-6), the differences in inflammatory mediator levels between the 2 groups no longer were significant. In contrast, the percentage of calcitonin gene-related peptide-immunoreactive neurons among Fluoro-gold-labeled DRG neurons, and the numbers of ionized calcium-binding adaptor molecule-1-immunoreactive microglia and glial fibrillary acidic protein-immunoreactive astrocytes in the spinal dorsal horn remained significantly higher in the injured group than in the noninjured group at all-time points (P < 0.05). CONCLUSION Disk injury in rats produces persistent increases in neuropeptides in DRGs and glia in the spinal cord, but only transient increases in inflammatory mediators in IVDs.
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Kim JS, Kroin JS, Li X, An HS, Buvanendran A, Yan D, Tuman KJ, van Wijnen AJ, Chen D, Im HJ. The rat intervertebral disk degeneration pain model: relationships between biological and structural alterations and pain. Arthritis Res Ther 2011; 13:R165. [PMID: 21996269 PMCID: PMC3308099 DOI: 10.1186/ar3485] [Citation(s) in RCA: 51] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/13/2011] [Revised: 06/09/2011] [Accepted: 10/13/2011] [Indexed: 12/19/2022] Open
Abstract
INTRODUCTION Degeneration of the interverterbral disk is as a cause of low-back pain is increasing. To gain insight into relationships between biological processes, structural alterations and behavioral pain, we created an animal model in rats. METHODS Disk degeneration was induced by removal of the nucleus pulposus (NP) from the lumbar disks (L4/L5 and L5/L6) of Sprague Dawley rats using a 0.5-mm-diameter microsurgical drill. The degree of primary hyperalgesia was assessed by using an algometer to measure pain upon external pressure on injured lumbar disks. Biochemical and histological assessments and radiographs of injured disks were used for evaluation. We investigated therapeutic modulation of chronic pain by administering pharmaceutical drugs in this animal model. RESULTS After removal of the NP, pressure hyperalgesia developed over the lower back. Nine weeks after surgery we observed damaged or degenerated disks with proteoglycan loss and narrowing of disk height. These biological and structural changes in disks were closely related to the sustained pain hyperalgesia. A high dose of morphine (6.7 mg/kg) resulted in effective pain relief. However, high doses of pregabalin (20 mg/kg), a drug that has been used for treatment of chronic neuropathic pain, as well as the anti-inflammatory drugs celecoxib (50 mg/kg; a selective inhibitor of cyclooxygenase 2 (COX-2)) and ketorolac (20 mg/kg; an inhibitor of COX-1 and COX-2), did not have significant antihyperalgesic effects in our disk injury animal model. CONCLUSIONS Although similarities in gene expression profiles suggest potential overlap in chronic pain pathways linked to disk injury or neuropathy, drug-testing results suggest that pain pathways linked to these two chronic pain conditions are mechanistically distinct. Our findings provide a foundation for future research on new therapeutic interventions that can lead to improvements in the treatment of patients with back pain due to disk degeneration.
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Affiliation(s)
- Jae-Sung Kim
- Department of Biochemistry, Rush University Medical Center, Cohn Research BD 516, 1735 West Harrison Street, Chicago, IL 60612, USA
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Abstract
STUDY DESIGN Gait analysis and immunohistological analysis in a rat model of myofascial inflammation in low back. OBJECTIVE To investigate gait in a rat model of myofascial inflammation using the CatWalk gait analysis system. SUMMARY OF BACKGROUND DATA There are few reports examining low back pain behavior in animal models. The CatWalk is a computer-assisted gait analysis system that provides an automated way to assess gait function and this behavior during pain. METHODS In a myofascial inflammation group, 0.5 mL of 4% paraformaldehyde buffer and 0.5 mL of 5% Fluoro-Gold (FG) buffer were injected into bilateral multifidus muscles of rats. In a control group, FG buffer alone was injected. Five days after surgery, the gait of rats in both groups was investigated using the CatWalk system. In the present study a total of 36 gait parameters were quantified and used to judge pain-related behavior. Bilateral dorsal root ganglia (DRGs) from L1 to L6 levels were resected, and immunostained for calcitonin gene-related peptide (CGRP). RESULTS In the myofascial inflammation group, the mean duty cycle (duration of paw contact divided by time between consecutive paw contacts) of each paws (front and hind) were significantly higher and mean stride length (the distance between successive placements of the same paw) of each paws were significantly shorter compared with the control group. Furthermore, mean minimum contact intensity of the complete paw and mean contact intensity of each paws in the myofascial inflammation group were significantly higher compared with the control group. The proportion of CGRP-immunoreactive FG-labeled neurons among all FG-labeled DRG neurons in the myofascial inflammation group was significantly higher than the proportion in the control group. CONCLUSION These results suggest that myofascial inflammation in low back caused the changes to the rat's gait, including long stands, short stride, and strong paw contact.
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Intervertebral Disc Degeneration-induced Expression of Pain-related Molecules. J Neurosurg Anesthesiol 2011; 23:329-34. [DOI: 10.1097/ana.0b013e318220f033] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/02/2023]
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