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Liu Y, Liang Y, Gao M, Li Y, Zhao T, Zhao Y. Animal Models of Complex Regional Pain Syndrome Type I. J Pain Res 2021; 14:3711-3721. [PMID: 34899000 PMCID: PMC8654689 DOI: 10.2147/jpr.s333270] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/08/2021] [Accepted: 10/28/2021] [Indexed: 12/01/2022] Open
Abstract
Complex regional pain syndrome (CRPS) is a chronic pain disorder characterized by spontaneous or evoked regionally-confined pain which is out of proportion to the initial trauma event. The disease can seriously affect the quality of the patients’ life, increase the psychological burden, and cause various degrees of disability. Despite the awareness of CRPS among medical practitioners for over a century, its pathogenesis remains unclear, and the available treatment is still unsatisfactory. Effective animal models are the foundation of disease research, which is helpful in understanding the pathogenesis and an in-depth exploration of the appropriate therapeutic approaches. Currently, researchers have established a series of animal models of the disease. There are four main CRPSI animal models: chronic post-ischemic pain (CPIP) model, tibial fracture/cast immobilization model, passive transfer-trauma model, and the needlestick-nerve-injury (NNI) model. The modeling methods of these models are constantly improving over time. In preclinical studies, the interpretation of experimental results and the horizontal comparison between similar studies may be affected by the nature of the experimental animal breeds, sex, diet, and psychology. There is need to facilitate the choice of appropriate animal models and avoid the interference of the factors influencing animal models on the interpretation of research results. The review will provide a basic overview of the influencing factors, modeling methods, and the characteristics of CRPSI animal models.
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Affiliation(s)
- Yu Liu
- Third Hospital of Shanxi Medical University, Shanxi Bethune Hospital, Shanxi Academy of Medical Sciences, Tongji Shanxi Hospital, Taiyuan, Shanxi, 030032, People's Republic of China
| | - Ying Liang
- Third Hospital of Shanxi Medical University, Shanxi Bethune Hospital, Shanxi Academy of Medical Sciences, Tongji Shanxi Hospital, Taiyuan, Shanxi, 030032, People's Republic of China
| | - Min Gao
- Third Hospital of Shanxi Medical University, Shanxi Bethune Hospital, Shanxi Academy of Medical Sciences, Tongji Shanxi Hospital, Taiyuan, Shanxi, 030032, People's Republic of China
| | - Yingchun Li
- Third Hospital of Shanxi Medical University, Shanxi Bethune Hospital, Shanxi Academy of Medical Sciences, Tongji Shanxi Hospital, Taiyuan, Shanxi, 030032, People's Republic of China
| | - Tingting Zhao
- Shaanxi University of Traditional Chinese Medicine, Xi'an, Shaanxi, 712046, People's Republic of China
| | - Yani Zhao
- Third Hospital of Shanxi Medical University, Shanxi Bethune Hospital, Shanxi Academy of Medical Sciences, Tongji Shanxi Hospital, Taiyuan, Shanxi, 030032, People's Republic of China
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Complex regional pain syndrome patient immunoglobulin M has pronociceptive effects in the skin and spinal cord of tibia fracture mice. Pain 2021; 161:797-809. [PMID: 31815913 DOI: 10.1097/j.pain.0000000000001765] [Citation(s) in RCA: 26] [Impact Index Per Article: 8.7] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/11/2022]
Abstract
It has been proposed that complex regional pain syndrome (CRPS) is a post-traumatic autoimmune disease. Previously, we observed that B cells are required for the full expression of CRPS-like changes in a mouse tibia fracture model and that serum immunoglobulin M (IgM) antibodies from fracture mice have pronociceptive effects in muMT fracture mice lacking B cells. The current study evaluated the pronociceptive effects of injecting CRPS patient serum or antibodies into muMT fracture mice by measuring hind paw allodynia and unweighting changes. Complex regional pain syndrome serum binding was measured against autoantigens previously identified in the fracture mouse model. Both CRPS patient serum or IgM antibodies had pronociceptive effects in the fracture limb when injected systemically in muMT fracture mice, but normal subject serum and CRPS patient IgG antibodies had no effect. Furthermore, CRPS serum IgM antibodies had pronociceptive effects when injected into the fracture limb hind paw skin or intrathecally in the muMT fracture mice. Early (1-12 months after injury) CRPS patient (n = 20) sera were always pronociceptive after systemic injection, and chronic (>12 months after injury) CRPS sera were rarely pronociceptive (2/20 patients), while sera from normal subjects (n = 20) and from patients with uncomplicated recoveries from orthopedic surgery and/or fracture (n = 15) were never pronociceptive. Increased CRPS serum IgM binding was observed for keratin 16, histone 3.2, gamma actin, and alpha enolase autoantigens. We postulate that CRPS patient IgM antibodies bind to neoantigens in the fracture mouse skin and spinal cord to initiate a regionally restricted pronociceptive complement response potentially contributing to the CRPS disease process.
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Price TJ, Gold MS. From Mechanism to Cure: Renewing the Goal to Eliminate the Disease of Pain. PAIN MEDICINE 2019; 19:1525-1549. [PMID: 29077871 DOI: 10.1093/pm/pnx108] [Citation(s) in RCA: 31] [Impact Index Per Article: 6.2] [Reference Citation Analysis] [Abstract] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
Abstract
Objective Persistent pain causes untold misery worldwide and is a leading cause of disability. Despite its astonishing prevalence, pain is undertreated, at least in part because existing therapeutics are ineffective or cause intolerable side effects. In this review, we cover new findings about the neurobiology of pain and argue that all but the most transient forms of pain needed to avoid tissue damage should be approached as a disease where a cure can be the goal of all treatment plans, even if attaining this goal is not yet always possible. Design We reviewed the literature to highlight recent advances in the area of the neurobiology of pain. Results We discuss barriers that are currently hindering the achievement of this goal, as well as the development of new therapeutic strategies. We also discuss innovations in the field that are creating new opportunities to treat and even reverse persistent pain, some of which are in late-phase clinical trials. Conclusion We conclude that the confluence of new basic science discoveries and development of new technologies are creating a path toward pain therapeutics that should offer significant hope of a cure for patients and practitioners alike. Classification of Evidence. Our review points to new areas of inquiry for the pain field to advance the goal of developing new therapeutics to treat chronic pain.
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Affiliation(s)
- Theodore J Price
- School of Behavioral and Brain Sciences, The University of Texas at Dallas, Dallas, Texas
| | - Michael S Gold
- Department of Neurobiology, University of Pittsburgh, Pittsburgh, Pennsylvania, USA
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Abstract
It has been proposed that complex regional pain syndrome (CRPS) is a posttraumatic autoimmune disease, and we previously observed that B cells are required for the full expression of CRPS-like changes in a mouse tibia fracture CRPS model. The current study used the mouse model to evaluate the progression of postfracture CRPS-like changes in wild-type (WT) and muMT fracture mice lacking B cells and antibodies. The pronociceptive effects of injecting WT fracture mouse serum antibodies into muMT fracture mice were also evaluated. Postfracture pain behaviors transitioned from being initially dependent on both innate and autoimmune inflammatory mechanisms at 3 weeks after fracture to being entirely mediated by antibody responses at 12 weeks after fracture and spontaneously resolving by 21 weeks after fracture. Furthermore, serum IgM antibodies from WT fracture mice had pronociceptive effects in the fracture limb when injected into muMT fracture mice. IgM antibody levels gradually increased in the fracture limb hind paw skin, sciatic nerve, and corresponding lumbar cord, peaking at 12 to 18 weeks after fracture and then declining. Immunohistochemistry localized postfracture IgM antibody binding to antigens in the fracture limb hind paw dermal cell nuclei. We postulate that fracture induces expression of neoantigens in the fracture limb skin, sciatic nerve, and cord, which trigger B cells to secret IgM antibodies that bind those antigens and initiate a pronociceptive antibody response. Autoimmunity plays a key role in the progression of nociceptive and vascular changes in the mouse fracture model and potentially contributes to the CRPS disease process.
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Elevated Plasma Levels of sIL-2R in Complex Regional Pain Syndrome: A Pathogenic Role for T-Lymphocytes? Mediators Inflamm 2017. [PMID: 28634419 PMCID: PMC5467333 DOI: 10.1155/2017/2764261] [Citation(s) in RCA: 27] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/15/2022] Open
Abstract
The immune system has long been thought to be involved in the pathophysiology of complex regional pain syndrome (CRPS). However, not much is known about the role of the immune system and specifically T-cells in the onset and maintenance of this disease. In this study, we aimed to evaluate T-cell activity in CRPS by comparing blood soluble interleukin-2 receptor (sIL-2R) levels between CRPS patients and healthy controls. CRPS patients had statistically significant elevated levels of sIL-2R as compared to healthy controls (median sIL-2R levels: 4151 pg/ml (Q3 − Q1 = 5731 pg/ml − 3546 pg/ml) versus 1907 pg/ml (Q3 − Q1: 2206 pg/ml − 1374 pg/ml), p < 0.001, resp.). Furthermore, sIL-2R level seems to be a good discriminator between CRPS patients and healthy controls with a high sensitivity (90%) and specificity (89.5%). Our finding indicates increased T-cell activity in patients with CRPS. This finding is of considerable relevance as it could point towards a T-cell-mediated inflammatory process in this disease. This could pave the way for new anti-inflammatory therapies in the treatment of CRPS. Furthermore, sIL-2R could be a promising new marker for determining inflammatory disease activity in CRPS.
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The prevalence of autoantibodies in complex regional pain syndrome type I. Mediators Inflamm 2015; 2015:718201. [PMID: 25741131 PMCID: PMC4337272 DOI: 10.1155/2015/718201] [Citation(s) in RCA: 28] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/27/2014] [Revised: 01/25/2015] [Accepted: 01/26/2015] [Indexed: 01/22/2023] Open
Abstract
Autoimmunity has been suggested as one of the pathophysiologic mechanisms that may underlie complex regional pain syndrome (CRPS). Screening for antinuclear antibodies (ANA) is one of the diagnostic tests, which is usually performed if a person is suspected to have a systemic autoimmune disease. Antineuronal antibodies are autoantibodies directed against antigens in the central and/or peripheral nervous system. The aim of this study was to compare the prevalence of these antibodies in CRPS patients with the normal values of those antibodies in the healthy population.
Twenty seven (33%) of the 82 CRPS patients of whom serum was available showed a positive ANA test. This prevalence is significantly higher than in the general population. Six patients (7.3%) showed a positive result for typical antineuronal antibodies. This proportion, however, does not deviate from that in the general population. Our findings suggest that autoantibodies may be associated with the pathophysiology of CRPS, at least in a subset of patients. Further research is needed into defining this subset and into the role of autoantibodies in the pathogenesis of CRPS.
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Breivik H. European Pain Management Discussion Forum. J Pain Palliat Care Pharmacother 2012. [DOI: 10.3109/15360288.2012.703299] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022]
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Walker S, Drummond PD. Implications of a Local Overproduction of Tumor Necrosis Factor-α in Complex Regional Pain Syndrome. PAIN MEDICINE 2011; 12:1784-807. [DOI: 10.1111/j.1526-4637.2011.01273.x] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/14/2023]
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