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Rodríguez-Palma EJ, Huerta de la Cruz S, Islas-Espinoza AM, Castañeda-Corral G, Granados-Soto V, Khanna R. Nociplastic pain mechanisms and toll-like receptors as promising targets for its management. Pain 2024; 165:2150-2164. [PMID: 38595206 DOI: 10.1097/j.pain.0000000000003238] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/06/2023] [Accepted: 02/29/2024] [Indexed: 04/11/2024]
Abstract
ABSTRACT Nociplastic pain, characterized by abnormal pain processing without an identifiable organic cause, affects a significant portion of the global population. Unfortunately, current pharmacological treatments for this condition often prove ineffective, prompting the need to explore new potential targets for inducing analgesic effects in patients with nociplastic pain. In this context, toll-like receptors (TLRs), known for their role in the immune response to infections, represent promising opportunities for pharmacological intervention because they play a relevant role in both the development and maintenance of pain. Although TLRs have been extensively studied in neuropathic and inflammatory pain, their specific contributions to nociplastic pain remain less clear, demanding further investigation. This review consolidates current evidence on the connection between TLRs and nociplastic pain, with a specific focus on prevalent conditions like fibromyalgia, stress-induced pain, sleep deprivation-related pain, and irritable bowel syndrome. In addition, we explore the association between nociplastic pain and psychiatric comorbidities, proposing that modulating TLRs can potentially alleviate both pain syndromes and related psychiatric disorders. Finally, we discuss the potential sex differences in TLR signaling, considering the higher prevalence of nociplastic pain among women. Altogether, this review aims to shed light on nociplastic pain, its underlying mechanisms, and its intriguing relationship with TLR signaling pathways, ultimately framing the potential therapeutic role of TLRs in addressing this challenging condition.
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Affiliation(s)
- Erick J Rodríguez-Palma
- Department of Pharmacology and Therapeutics, College of Medicine, University of Florida, Gainesville, FL, United States
- Neurobiology of Pain Laboratory, Departamento de Farmacobiología, Cinvestav, South Campus, Mexico City, Mexico
| | | | - Ana M Islas-Espinoza
- Neurobiology of Pain Laboratory, Departamento de Farmacobiología, Cinvestav, South Campus, Mexico City, Mexico
| | | | - Vinicio Granados-Soto
- Neurobiology of Pain Laboratory, Departamento de Farmacobiología, Cinvestav, South Campus, Mexico City, Mexico
| | - Rajesh Khanna
- Department of Pharmacology and Therapeutics, College of Medicine, University of Florida, Gainesville, FL, United States
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Grillo R, Balel Y, Brozoski MA, Ali K, Adebayo ET, Naclério-Homem MDG. A global science mapping analysis on odontogenic infections. JOURNAL OF STOMATOLOGY, ORAL AND MAXILLOFACIAL SURGERY 2024; 125:101513. [PMID: 37207960 DOI: 10.1016/j.jormas.2023.101513] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/13/2023] [Accepted: 05/16/2023] [Indexed: 05/21/2023]
Abstract
OBJECTIVES Odontogenic infections are common and a topic of core interest for dentists, and maxillofacial surgeons. The aim of this study was to conduct a bibliometric analysis of the global literature on odontogenic infection and explore the top 100 most cited papers to identify the common causes, sequelae and management trends. METHODS Following a comprehensive literature search, a list of top 100 most cited papers was created. The VOSviewer software (Leiden University, The Netherlands) was used to create a graphical representation of the data, and statistical analyses were performed to analyze the characteristics of the top 100 most cited papers. RESULTS A total of 1,661 articles were retrieved with the first article published in 1947. There is an exponential upward trend on the number of publications (R2 = 0.919) and a majority of papers are in English language (n = 1,577, 94.94%). A total of 22,041 citations were found with a mean of 13.27 per article. The highest number of publications were recorded from developed countries. There was a male predilection in the reported cases and the most common sites included the submandibular and parapharyngeal spaces. Diabetes mellitus was identified as the commonest co-morbidity. Surgical drainage was ascertained to be the preferred method of management. CONCLUSIONS Odontogenic infections remain prevalent and have a global distribution. Although prevention of odontogenic infection through meticulous dental care is ideal, early diagnosis and prompt management of established odontogenic infections is important to avoid morbidities and mortality. Surgical drainage is the most effective management strategy. There is lack of consensus regarding the role of antibiotics in the management of odontogenic infections.
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Affiliation(s)
- Ricardo Grillo
- Department of Oral & Maxillofacial Surgery, Traumatology and Prosthesis - Faculty of Dentistry of the University of São Paulo, Brazil; Department of Oral & Maxillofacial Surgery, Faculdade Patos de Minas, Brasília, Brazil.
| | - Yunus Balel
- Department of Oral and Maxillofacial Surgery, Gaziosmanpasa University, Gaziosmanpasa, Turkey
| | - Mariana Aparecida Brozoski
- Department of Oral & Maxillofacial Surgery, Traumatology and Prosthesis - Faculty of Dentistry of the University of São Paulo, Brazil
| | - Kamran Ali
- College of Dental Medicine, Qatar University, Doha, Qatar
| | - Ezekiel Taiwo Adebayo
- Department of Oral and Maxillofacial Surgery, University of Medical Sciences, Ondo, Nigeria
| | - Maria da Graça Naclério-Homem
- Department of Oral & Maxillofacial Surgery, Traumatology and Prosthesis - Faculty of Dentistry of the University of São Paulo, Brazil
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Li HL, Shao LH, Chen X, Wang M, Qin QJ, Yang YL, Zhang GR, Hai Y, Tian YH. Anti-inflammatory and DNA Repair Effects of Astragaloside IV on PC12 Cells Damaged by Lipopolysaccharide. Curr Med Sci 2024; 44:854-863. [PMID: 39112916 DOI: 10.1007/s11596-024-2912-0] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/13/2023] [Accepted: 06/06/2024] [Indexed: 08/23/2024]
Abstract
OBJECTIVE This study aimed to establish a neural cell injury model in vitro by stimulating PC12 cells with lipopolysaccharide (LPS) and to examine the effects of astragaloside IV on key targets using high-throughput sequence technology and bioinformatics analyses. METHODS PC12 cells in the logarithmic growth phase were treated with LPS at final concentrations of 0.25, 0.5, 0.75, 1, and 1.25 mg/mL for 24 h. Cell morphology was evaluated, and cell survival rates were calculated. A neurocyte inflammatory model was established with LPS treatment, which reached a 50% cell survival rate. PC12 cells were treated with 0.01, 0.1, 1, 10, or 100 µmol/L astragaloside IV for 24 h. The concentration of astragaloside IV that did not affect the cell survival rate was selected as the treatment group for subsequent experiments. NOS activity was detected by colorimetry; the expression levels of ERCC2, XRCC4, XRCC2, TNF-α, IL-1β, TLR4, NOS and COX-2 mRNA and protein were detected by RT-qPCR and Western blotting. The differentially expressed genes (DEGs) between the groups were screened using a second-generation sequence (fold change>2, P<0.05) with the following KEGG enrichment analysis, RT-qPCR and Western blotting were used to detect the mRNA and protein expression of DEGs related to the IL-17 pathway in different groups of PC12 cells. RESULTS The viability of PC12 cells was not altered by treatment with 0.01, 0.1, or 1 µmol/L astragaloside IV for 24 h (P>0.05). However, after treatment with 0.5, 0.75, 1, or 1.25 mg/mL LPS for 24 h, the viability steadily decreased (P<0.01). The mRNA and protein expression levels of ERCC2, XRCC4, XRCC2, TNF-α, IL-1β, TLR4, NOS, and COX-2 were significantly increased after PC12 cells were treated with 1 mg/mL LPS for 24 h (P<0.01); however, these changes were reversed when PC12 cells were pretreated with 0.01, 0.1, or 1 µmol/L astragaloside IV in PC12 cells and then treated with 1 mg/mL LPS for 24 h (P<0.05). Second-generation sequencing revealed that 1026 genes were upregulated, while 1287 genes were downregulated. The DEGs were associated with autophagy, TNF-α, interleukin-17, MAPK, P53, Toll-like receptor, and NOD-like receptor signaling pathways. Furthermore, PC12 cells treated with a 1 mg/mL LPS for 24 h exhibited increased mRNA and protein expression of CCL2, CCL11, CCL7, MMP3, and MMP10, which are associated with the IL-17 pathway. RT-qPCR and Western blotting analyses confirmed that the DEGs listed above corresponded to the sequence assay results. CONCLUSION LPS can damage PC12 cells and cause inflammatory reactions in nerve cells and DNA damage. astragaloside IV plays an anti-inflammatory and DNA damage protective role and inhibits the IL-17 signaling pathway to exert a neuroprotective effect in vitro.
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Affiliation(s)
- Hai-Long Li
- Department of Geriatrics, The Affiliated Hospital of Gansu University of Chinese Medicine, Lanzhou, 730000, China
- Key Laboratory for Mining, Innovation and Transformation of Traditional Chinese Medicine in Gansu Province and the New Product Creation Engineering Laboratory of Traditional Chinese Medicine in Gansu Province, Lanzhou, 730000, China
| | - Li-Hua Shao
- Key Laboratory for Mining, Innovation and Transformation of Traditional Chinese Medicine in Gansu Province and the New Product Creation Engineering Laboratory of Traditional Chinese Medicine in Gansu Province, Lanzhou, 730000, China
| | - Xi Chen
- Key Laboratory for Mining, Innovation and Transformation of Traditional Chinese Medicine in Gansu Province and the New Product Creation Engineering Laboratory of Traditional Chinese Medicine in Gansu Province, Lanzhou, 730000, China
| | - Meng Wang
- Key Laboratory for Mining, Innovation and Transformation of Traditional Chinese Medicine in Gansu Province and the New Product Creation Engineering Laboratory of Traditional Chinese Medicine in Gansu Province, Lanzhou, 730000, China
| | - Qi-Jie Qin
- Department of Neurology, the First People's Hospital of Lanzhou, Lanzhou, Gansu, 730000, China
| | - Ya-Li Yang
- Key Laboratory for Mining, Innovation and Transformation of Traditional Chinese Medicine in Gansu Province and the New Product Creation Engineering Laboratory of Traditional Chinese Medicine in Gansu Province, Lanzhou, 730000, China
- School of Public Health, Gansu University of Chinese Medicine, Lanzhou, 730000, China
| | | | - Yang Hai
- Scientific Research and Experimental Center, Gansu University of Chinese Medicine, Lanzhou, 730000, China.
| | - Yi-Hong Tian
- School of Public Health, Gansu University of Chinese Medicine, Lanzhou, 730000, China.
- Scientific Research and Experimental Center, Gansu University of Chinese Medicine, Lanzhou, 730000, China.
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Hsu JCN, Tseng HW, Chen CH, Lee TS. Transient receptor potential vanilloid 1 interacts with Toll-like receptor 4 (TLR4)/cluster of differentiation 14 (CD14) signaling pathway in lipopolysaccharide-mediated inflammation in macrophages. Exp Anim 2024; 73:336-346. [PMID: 38508727 PMCID: PMC11254490 DOI: 10.1538/expanim.23-0148] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/27/2023] [Accepted: 03/16/2024] [Indexed: 03/22/2024] Open
Abstract
Transient receptor potential vanilloid 1 (TRPV1), a ligand-gated cation channel, is a receptor for vanilloids on sensory neurons and is also activated by capsaicin, heat, protons, arachidonic acid metabolites, and inflammatory mediators on neuronal or non-neuronal cells. However, the role of the TRPV1 receptor in pro-inflammatory cytokine secretion and its potential regulatory mechanisms in lipopolysaccharide (LPS)-induced inflammation has yet to be entirely understood. To investigate the role and regulatory mechanism of the TRPV1 receptor in regulating LPS-induced inflammatory responses, bone marrow-derived macrophages (BMDMs) harvested from wild-type (WT) and TRPV1 deficient (Trpv1-/-) mice were used as the cell model. In WT BMDMs, LPS induced an increase in the levels of tumor necrosis factor-α, IL-1β, inducible nitric oxide synthase, and nitric oxide, which were attenuated in Trpv1-/- BMDMs. Additionally, the phosphorylation of inhibitor of nuclear factor kappa-Bα and mitogen-activated protein kinases, as well as the translocation of nuclear factor kappa-B and activator protein 1, were all decreased in LPS-treated Trpv1-/- BMDMs. Immunoprecipitation assay revealed that LPS treatment increased the formation of TRPV1-Toll-like receptor 4 (TLR4)-cluster of differentiation 14 (CD14) complex in WT BMDMs. Genetic deletion of TRPV1 in BMDMs impaired the LPS-triggered immune-complex formation of TLR4, myeloid differentiation protein 88, and interleukin-1 receptor-associated kinase, all of which are essential regulators in LPS-induced activation of the TLR4 signaling pathway. Moreover, genetic deletion of TRPV1 prevented the LPS-induced lethality and pro-inflammatory production in mice. In conclusion, the TRPV1 receptor may positively regulate the LPS-mediated inflammatory responses in macrophages by increasing the interaction with the TLR4-CD14 complex and activating the downstream signaling cascade.
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Affiliation(s)
- Julia Chu-Ning Hsu
- Department of Veterinary Medicine, College of Veterinary Medicine, National Chung Hsing University, 145, Xingda Road, South District, Taichung 402202, Taiwan
| | - Hsu-Wen Tseng
- Department of Physiology, School of Medicine, National Yang-Ming University, 155, Sec. 2, Linong Street, Taipei 112304, Taiwan
| | - Chia-Hui Chen
- Graduate Institute and Department of Physiology, College of Medicine, National Taiwan University, 1, Sec. 1, Jen-Ai Road, Taipei 100233, Taiwan
| | - Tzong-Shyuan Lee
- Graduate Institute and Department of Physiology, College of Medicine, National Taiwan University, 1, Sec. 1, Jen-Ai Road, Taipei 100233, Taiwan
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Li HL, Zhang Y, Zhou JW. Acupuncture for radicular pain: a review of analgesic mechanism. Front Mol Neurosci 2024; 17:1332876. [PMID: 38596777 PMCID: PMC11002172 DOI: 10.3389/fnmol.2024.1332876] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/07/2023] [Accepted: 02/28/2024] [Indexed: 04/11/2024] Open
Abstract
Radicular pain, a common and complex form of neuropathic pain, presents significant challenges in treatment. Acupuncture, a therapy originating from ancient traditional Chinese medicine and widely utilized for various pain types, including radicular pain, has shown promising outcomes in the management of lumbar radicular pain, cervical radicular pain, and radicular pain due to spinal stenosis. Despite its efficacy, the exact mechanisms through which acupuncture achieves analgesia are not fully elucidated and are the subject of ongoing research. This review sheds light on the current understanding of the analgesic mechanisms of acupuncture for radicular pain, offering valuable perspectives for both clinical application and basic scientific research. Acupuncture is postulated to relieve radicular pain by several mechanisms: peripherally, it reduces muscle spasms, lessens mechanical pressure on nerve roots, and improves microcirculation; at the molecular level, it inhibits the HMGB1/RAGE and TLR4/NF-κB signaling pathways, thereby decreasing the release of pro-inflammatory cytokines; within the spinal cord, it influences synaptic plasticity; and centrally, it modulates brain function, particularly affecting the medial prefrontal cortex, anterior cingulate cortex, and thalamus within the default mode network. By acting across these diverse biological domains, acupuncture presents an effective treatment modality for radicular pain, and deepening our understanding of the underlying mechanisms regarding analgesia for radicular pain is crucial for enhancing its clinical efficacy and advancement in pain management.
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Affiliation(s)
- Hong-Lin Li
- School of Acupuncture and Tuina, Chengdu University of Traditional Chinese Medicine, Chengdu, China
| | - Yi Zhang
- School of Acupuncture and Tuina, Chengdu University of Traditional Chinese Medicine, Chengdu, China
| | - Jian-Wei Zhou
- Academy of Traditional Chinese Medicine Sciences, Chengdu, Sichuan, China
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6
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Araldi D, Khomula EV, Bonet IJM, Bogen O, Green PG, Levine JD. Role of pattern recognition receptors in chemotherapy-induced neuropathic pain. Brain 2024; 147:1025-1042. [PMID: 37787114 PMCID: PMC10907096 DOI: 10.1093/brain/awad339] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/23/2023] [Revised: 07/25/2023] [Accepted: 09/12/2023] [Indexed: 10/04/2023] Open
Abstract
Progress in the development of effective chemotherapy is producing a growing population of patients with acute and chronic painful chemotherapy-induced peripheral neuropathy (CIPN), a serious treatment-limiting side effect for which there is currently no US Food and Drug Administration-approved treatment. CIPNs induced by diverse classes of chemotherapy drugs have remarkably similar clinical presentations, leading to the suggestion they share underlying mechanisms. Sensory neurons share with immune cells the ability to detect damage associated molecular patterns (DAMPs), molecules produced by diverse cell types in response to cellular stress and injury, including by chemotherapy drugs. DAMPs, in turn, are ligands for pattern recognition receptors (PRRs), several of which are found on sensory neurons, as well as satellite cells, and cells of the immune system. In the present experiments, we evaluated the role of two PRRs, TLR4 and RAGE, present in dorsal root ganglion (DRG), in CIPN. Antisense (AS)-oligodeoxynucleotides (ODN) against TLR4 and RAGE mRNA were administered intrathecally before ('prevention protocol') or 3 days after ('reversal protocol') the last administration of each of three chemotherapy drugs that treat cancer by different mechanisms (oxaliplatin, paclitaxel and bortezomib). TLR4 and RAGE AS-ODN prevented the development of CIPN induced by all three chemotherapy drugs. In the reversal protocol, however, while TLR4 AS-ODN completely reversed oxaliplatin- and paclitaxel-induced CIPN, in rats with bortezomib-induced CIPN it only produced a temporary attenuation. RAGE AS-ODN, in contrast, reversed CIPN induced by all three chemotherapy drugs. When a TLR4 antagonist was administered intradermally to the peripheral nociceptor terminal, it did not affect CIPN induced by any of the chemotherapy drugs. However, when administered intrathecally, to the central terminal, it attenuated hyperalgesia induced by all three chemotherapy drugs, compatible with a role of TLR4 in neurotransmission at the central terminal but not sensory transduction at the peripheral terminal. Finally, since it has been established that cultured DRG neurons can be used to study direct effects of chemotherapy on nociceptors, we also evaluated the role of TLR4 in CIPN at the cellular level, using patch-clamp electrophysiology in DRG neurons cultured from control and chemotherapy-treated rats. We found that increased excitability of small-diameter DRG neurons induced by in vivo and in vitro exposure to oxaliplatin is TLR4-dependent. Our findings suggest that in addition to the established contribution of PRR-dependent neuroimmune mechanisms, PRRs in DRG cells also have an important role in CIPN.
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Affiliation(s)
- Dionéia Araldi
- Department of Oral and Maxillofacial Surgery, UCSF Pain and Addiction Research Center, University of California at San Francisco, San Francisco, CA 94143, USA
| | - Eugen V Khomula
- Department of Oral and Maxillofacial Surgery, UCSF Pain and Addiction Research Center, University of California at San Francisco, San Francisco, CA 94143, USA
| | - Ivan J M Bonet
- Department of Oral and Maxillofacial Surgery, UCSF Pain and Addiction Research Center, University of California at San Francisco, San Francisco, CA 94143, USA
| | - Oliver Bogen
- Department of Oral and Maxillofacial Surgery, UCSF Pain and Addiction Research Center, University of California at San Francisco, San Francisco, CA 94143, USA
| | - Paul G Green
- Department of Oral and Maxillofacial Surgery, UCSF Pain and Addiction Research Center, University of California at San Francisco, San Francisco, CA 94143, USA
- Department of Preventative and Restorative Dental Sciences, Division of Neuroscience, University of California at San Francisco, San Francisco, CA 94143, USA
| | - Jon D Levine
- Department of Oral and Maxillofacial Surgery, UCSF Pain and Addiction Research Center, University of California at San Francisco, San Francisco, CA 94143, USA
- Department of Medicine, Division of Neuroscience, University of California at San Francisco, San Francisco, CA 94143, USA
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Diogenes A. A Case of Respiratory Epithelium-Lined Cyst with Enriched Nociceptor Innervation. J Endod 2024; 50:389-394. [PMID: 38141830 DOI: 10.1016/j.joen.2023.12.003] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/14/2023] [Revised: 12/15/2023] [Accepted: 12/16/2023] [Indexed: 12/25/2023]
Abstract
Apical lesions of endodontic origin can be classified as either granulomas or cysts. In rare cases, respiratory epithelium can proliferate and encapsulate a lesion, forming a cyst. Moreover, the innervation of apical lesions has only been previously reported in animal models of apical periodontitis. This report demonstrates an unusual case in which tooth #15 was initially treated with nonsurgical root canal therapy. Still, the patient remained in moderate to severe pain for several days following the procedure. Next, an intentional replantation was performed in which a periapical cyst was curetted from the alveolus. The patient experienced immediate pain relief following the procedure. Histological analysis revealed that the periapical cyst was lined entirely with respiratory epithelium, and immunohistochemical analysis showed it to be densely innervated. In addition, these nerve fibers expressed the LPS receptor, TLR4. This is the first demonstration of the innervation pattern of a periapical cyst. Further studies are warranted to evaluate innervation in apical lesions and its correlation with pre- and intra-operative symptoms and their participation in the pathogenesis of apical periodontitis.
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Affiliation(s)
- Anibal Diogenes
- Department of Endodontics, University of Texas Health San Antonio, San Antonio, Texas.
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Khomula EV, Araldi D, Green PG, Levine JD. Sensitization of human and rat nociceptors by low dose morphine is toll-like receptor 4-dependent. Mol Pain 2024; 20:17448069241227922. [PMID: 38195088 PMCID: PMC10851754 DOI: 10.1177/17448069241227922] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/23/2023] [Accepted: 01/06/2024] [Indexed: 01/11/2024] Open
Abstract
While opioids remain amongst the most effective treatments for moderate-to-severe pain, their substantial side effect profile remains a major limitation to broader clinical use. One such side effect is opioid-induced hyperalgesia (OIH), which includes a transition from opioid-induced analgesia to pain enhancement. Evidence in rodents supports the suggestion that OIH may be produced by the action of opioids at Toll-like Receptor 4 (TLR4) either on immune cells that, in turn, produce pronociceptive mediators to act on nociceptors, or by a direct action at nociceptor TLR4. And, sub-analgesic doses of several opioids have been shown to induce hyperalgesia in rodents by their action as TLR4 agonists. In the present in vitro patch-clamp electrophysiology experiments, we demonstrate that low dose morphine directly sensitizes human as well as rodent dorsal root ganglion (DRG) neurons, an effect of this opioid analgesic that is antagonized by LPS-RS Ultrapure, a selective TLR4 antagonist. We found that low concentration (100 nM) of morphine reduced rheobase in human (by 36%) and rat (by 26%) putative C-type nociceptors, an effect of morphine that was markedly attenuated by preincubation with LPS-RS Ultrapure. Our findings support the suggestion that in humans, as in rodents, OIH is mediated by the direct action of opioids at TLR4 on nociceptors.
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Affiliation(s)
- Eugen V Khomula
- Department of Oral & Maxillofacial Surgery, University of California at San Francisco, San Francisco, CA, USA
| | - Dionéia Araldi
- Department of Oral & Maxillofacial Surgery, University of California at San Francisco, San Francisco, CA, USA
| | - Paul G Green
- Department of Oral & Maxillofacial Surgery, University of California at San Francisco, San Francisco, CA, USA
- Department of Preventative & Restorative Dental Sciences, and Division of Neuroscience, University of California at San Francisco, San Francisco, CA, USA
| | - Jon D Levine
- Department of Oral & Maxillofacial Surgery, University of California at San Francisco, San Francisco, CA, USA
- Department of Medicine, Division of Neuroscience, and UCSF Pain and Addiction Research Center, University of California at San Francisco, San Francisco, CA, USA
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9
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Khomula EV, Levine JD. Sensitization of Human and Rat Nociceptors by Low Dose Morphine is TLR4-dependent. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2023:2023.12.19.572472. [PMID: 38187676 PMCID: PMC10769211 DOI: 10.1101/2023.12.19.572472] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/09/2024]
Abstract
While opioids remain amongst the most effective treatments for moderate-to-severe pain, their substantial side effect profile remains a major limitation to broader clinical use. One such side effect is opioid-induced hyperalgesia (OIH), which includes a transition from opioid-induced analgesia to pain enhancement. Evidence in rodents supports the suggestion that OIH may be produced by the action of opioids at Toll-like Receptor 4 (TLR4) either on immune cells that, in turn, produce pronociceptive mediators to act on nociceptors, or by a direct action at nociceptor TLR4. And, sub-analgesic doses of several opioids have been shown to induce hyperalgesia in rodents by their action as TLR4 agonists. In the present in vitro patch-clamp electrophysiology experiments, we demonstrate that low dose morphine directly sensitizes human as well as rodent dorsal root ganglion (DRG) neurons, an effect of this opioid analgesic that is antagonized by LPS-RS Ultrapure, a selective TLR4 antagonist. We found that morphine (100 nM) reduced rheobase in human (by 36%) and rat (by 26%) putative C-type nociceptors, an effect of morphine that was markedly attenuated by preincubation with LPS-RS Ultrapure. Our findings support the suggestion that in humans, as well as in rodents, OIH is mediated by the direct action of opioids at TLR4 on nociceptors.
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Michot B, Casey SM, Lee CS, Erdogan O, Basu H, Chiu I, Gibbs JL. Lipopolysaccharide-Induced TRPA1 Upregulation in Trigeminal Neurons is Dependent on TLR4 and Vesicular Exocytosis. J Neurosci 2023; 43:6731-6744. [PMID: 37643860 PMCID: PMC10552941 DOI: 10.1523/jneurosci.0162-23.2023] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/27/2023] [Revised: 07/28/2023] [Accepted: 07/31/2023] [Indexed: 08/31/2023] Open
Abstract
Pain from bacterial infection was believed to be the consequence of inflammation induced by bacterial products. However recent studies have shown that bacterial products can directly activate sensory neurons and induce pain. The mechanisms by which bacteria induce pain are poorly understood, but toll-like receptor (TLR)4 and transient receptor potential A1 (TRPA1) receptors are likely important integrators of pain signaling induced by bacteria. Using male and female mice we show that sensory neuron activation by bacterial lipopolysaccharides (LPS) is mediated by both TRPA1 and TLR4 and involves the mobilization of extracellular and intracellular calcium. We also show that LPS induces neuronal sensitization in a process dependent on TLR4 receptors. Moreover, we show that TLR4 and TRPA1 are both involved in sensory neurons response to LPS stimulation. Activation of TLR4 in a subset of sensory neurons induces TRPA1 upregulation at the cell membrane through vesicular exocytosis, contributing to the initiation of neuronal sensitization and pain. Collectively these data highlight the importance of sensory neurons to pathogen detection, and their activation by bacterial products like LPS as potentially important to early immune and nociceptive responses.SIGNIFICANCE STATEMENT Bacterial infections are often painful and the recent discovery that bacteria can directly stimulate sensory neurons leading to pain sensation and modulation of immune system have highlighted the importance of nervous system in the response to bacterial infection. Here, we showed that lipopolysaccharide, a major bacterial by-product, requires both toll-like receptor (TLR)4 and transient receptor potential A1 (TRPA1) receptors for neuronal activation and acute spontaneous pain, but only TLR4 mediates sensory neurons sensitization. Moreover, we showed for the first time that TLR4 sensitize sensory neurons through a rapid upregulation of TRPA1 via vesicular exocytosis. Our data highlight the importance of sensory neurons to pathogen detection and suggests that TLR4 would be a potential therapeutic target to modulate early stage of bacteria-induced pain and immune response.
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Affiliation(s)
- Benoit Michot
- Department of Restorative Dentistry and Biomaterials Sciences, Harvard School of Dental Medicine, Boston, Massachusetts 02115
- Department of Endodontics, New York University College of Dentistry, New York, New York 10010
| | - Sharon M Casey
- Department of Restorative Dentistry and Biomaterials Sciences, Harvard School of Dental Medicine, Boston, Massachusetts 02115
- Department of Endodontics, New York University College of Dentistry, New York, New York 10010
| | - Caroline S Lee
- Department of Endodontics, New York University College of Dentistry, New York, New York 10010
| | - Ozge Erdogan
- Department of Restorative Dentistry and Biomaterials Sciences, Harvard School of Dental Medicine, Boston, Massachusetts 02115
| | - Himanish Basu
- Department of Immunology, Harvard Medical School, Boston, Massachusetts 02215
| | - Isaac Chiu
- Department of Immunology, Harvard Medical School, Boston, Massachusetts 02215
| | - Jennifer L Gibbs
- Department of Restorative Dentistry and Biomaterials Sciences, Harvard School of Dental Medicine, Boston, Massachusetts 02115
- Department of Endodontics, New York University College of Dentistry, New York, New York 10010
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11
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Tamagawa-Mineoka R. Toll-like receptors: their roles in pathomechanisms of atopic dermatitis. Front Immunol 2023; 14:1239244. [PMID: 37731494 PMCID: PMC10508237 DOI: 10.3389/fimmu.2023.1239244] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/13/2023] [Accepted: 08/22/2023] [Indexed: 09/22/2023] Open
Abstract
The skin functions as a physical barrier and represents the first line of the innate immune system. There is increasing evidence that toll-like receptors (TLRs) are involved in the pathomechanisms of not only infectious diseases, but also non-infectious inflammatory diseases. Interestingly, it has been demonstrated that TLRs recognize both exogenous threats, e.g. bacteria and viruses, and endogenous danger signals related to inflammation, cell necrosis, or tissue damage. Atopic dermatitis (AD) is a chronic relapsing inflammatory skin disease, which is associated with impaired skin barrier function, increased skin irritability to non-specific stimuli, and percutaneous sensitization. The impairment of skin barrier function in AD allows various stimuli, such as potential allergens and pathogens, to penetrate the skin and activate the innate immune system, including TLR signaling, which can lead to the development of adaptive immune reactions. In this review, I summarize the current understanding of the roles of TLR signaling in the pathogenesis of AD, with special emphasis on skin barrier function and inflammation.
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Affiliation(s)
- Risa Tamagawa-Mineoka
- Department of Dermatology, Graduate School of Medical Science, Kyoto Prefectural University of Medicine, Kyoto, Japan
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12
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Menon N, Kishen A. Nociceptor-Macrophage Interactions in Apical Periodontitis: How Biomolecules Link Inflammation with Pain. Biomolecules 2023; 13:1193. [PMID: 37627258 PMCID: PMC10452348 DOI: 10.3390/biom13081193] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/20/2023] [Revised: 07/20/2023] [Accepted: 07/24/2023] [Indexed: 08/27/2023] Open
Abstract
Periradicular tissues have a rich supply of peripheral afferent neurons, also known as nociceptive neurons, originating from the trigeminal nerve. While their primary function is to relay pain signals to the brain, these are known to be involved in modulating innate and adaptive immunity by initiating neurogenic inflammation (NI). Studies have investigated neuroanatomy and measured the levels of biomolecules such as cytokines and neuropeptides in human saliva, gingival crevicular fluid, or blood/serum samples in apical periodontitis (AP) to validate the possible role of trigeminal nociceptors in inflammation and tissue regeneration. However, the contributions of nociceptors and the mechanisms involved in the neuro-immune interactions in AP are not fully understood. This narrative review addresses the complex biomolecular interactions of trigeminal nociceptors with macrophages, the effector cells of the innate immune system, in the clinical manifestations of AP.
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Affiliation(s)
| | - Anil Kishen
- Dental Research Institute, Faculty of Dentistry, University of Toronto, Toronto, ON M5G 1G6, Canada;
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13
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Wyart C, Ki Jim K, Prendergast A. Sensory systems in the peripheral and central nervous systems shape host response during infections. Neuroscience 2023:S0306-4522(23)00303-2. [PMID: 37419406 DOI: 10.1016/j.neuroscience.2023.07.008] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 07/09/2023]
Abstract
The function of sensory cells has been largely investigated in the field of neuroscience for how they report the physical and chemical changes of the environment ("exteroception") and of internal physiology ("interoception"). Investigations over the last century have largely focused on the morphological, electrical and receptor properties of sensory cells in the nervous system focusing on conscious perception of external cues or homeostatic regulation upon detection of internal cues. Research in the last decade has uncovered that sensory cells can often sense polymodal cues, such as mechanical, chemical, and/ or thermal. Furthermore, sensory cells in the peripheral as well as in the central nervous system can detect evidence associated with the invasion of pathogenic bacteria or viruses. The corresponding neuronal activation associated with the presence of pathogens can impact their classical functions within the nervous system and trigger the release of compounds modulating the response to intruders, either triggering pain to raise awareness, enhancing host defense or sometimes, aggravating the infection. This perspective brings to light the need for interdisciplinary training in immunology, microbiology and neuroscience for the next generation of investigators in this field.
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Affiliation(s)
- Claire Wyart
- Sorbonne Université, INSERM U1127, UMR CNRS 7225, Institut du Cerveau (ICM), 47 bld de l'hôpital, Paris 75013, France.
| | - Kin Ki Jim
- Department of Fundamental Microbiology, Faculty of Biology and Medicine, University of Lausanne, Biophore Building, 1015, Lausanne, Switzerland
| | - Andrew Prendergast
- Comparative Medicine, 300 George St., Room 0752, New Haven, CT 06511, United States
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14
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Rodríguez-Palma EJ, Velazquez-Lagunas I, Salinas-Abarca AB, Vidal-Cantú GC, Escoto-Rosales MJ, Castañeda-Corral G, Fernández-Guasti A, Granados-Soto V. Spinal alarmin HMGB1 and the activation of TLR4 lead to chronic stress-induced nociceptive hypersensitivity in rodents. Eur J Pharmacol 2023:175804. [PMID: 37244377 DOI: 10.1016/j.ejphar.2023.175804] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/17/2023] [Revised: 05/11/2023] [Accepted: 05/22/2023] [Indexed: 05/29/2023]
Abstract
Chronic stress affects millions of people around the world, and it can trigger different behavioral disorders like nociceptive hypersensitivity and anxiety, among others. However, the mechanisms underlaying these chronic stress-induced behavioral disorders have not been yet elucidated. This study was designed to understand the role of high-mobility group box-1 (HMGB1) and toll-like receptor 4 (TLR4) in chronic stress-induced nociceptive hypersensitivity. Chronic restraint stress induced bilateral tactile allodynia, anxiety-like behaviors, phosphorylation of ERK and p38MAPK and activation of spinal microglia. Moreover, chronic stress enhanced HMGB1 and TLR4 protein expression at the dorsal root ganglion, but not at the spinal cord. Intrathecal injection of HMGB1 or TLR4 antagonists reduced tactile allodynia and anxiety-like behaviors induced by chronic stress. Additionally, deletion of TLR4 diminished the establishment of chronic stress-induced tactile allodynia in male and female mice. Lastly, the antiallodynic effect of HMGB1 and TLR4 antagonists were similar in stressed male and female rats and mice. Our results suggest that chronic restraint stress induces nociceptive hypersensitivity, anxiety-like behaviors, and up-regulation of spinal HMGB1 and TLR4 expression. Blockade of HMGB1 and TLR4 reverses chronic restraint stress-induced nociceptive hypersensitivity and anxiety-like behaviors and restores altered HMGB1 and TLR4 expression. The antiallodynic effects of HMGB1 and TLR4 blockers in this model are sex independent. TLR4 could be a potential pharmacological target for the treatment of the nociceptive hypersensitivity associated with widespread chronic pain.
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Affiliation(s)
- Erick J Rodríguez-Palma
- Neurobiology of Pain Laboratory, Departamento de Farmacobiología, Cinvestav, South Campus, Mexico City, Mexico
| | - Isabel Velazquez-Lagunas
- Neurobiology of Pain Laboratory, Departamento de Farmacobiología, Cinvestav, South Campus, Mexico City, Mexico
| | - Ana Belen Salinas-Abarca
- Neurobiology of Pain Laboratory, Departamento de Farmacobiología, Cinvestav, South Campus, Mexico City, Mexico
| | - Guadalupe C Vidal-Cantú
- Neurobiology of Pain Laboratory, Departamento de Farmacobiología, Cinvestav, South Campus, Mexico City, Mexico
| | - María J Escoto-Rosales
- Neurobiology of Pain Laboratory, Departamento de Farmacobiología, Cinvestav, South Campus, Mexico City, Mexico
| | | | | | - Vinicio Granados-Soto
- Neurobiology of Pain Laboratory, Departamento de Farmacobiología, Cinvestav, South Campus, Mexico City, Mexico.
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15
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Li Z, Chen A, Wan H, Gao X, Li C, Xiong L, Liang H. Immunohistochemical Localization of MD2, a Co-Receptor of TLR4, in the Adult Mouse Brain. ACS Chem Neurosci 2023; 14:400-417. [PMID: 36657737 PMCID: PMC9897217 DOI: 10.1021/acschemneuro.2c00540] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/07/2022] [Accepted: 01/04/2023] [Indexed: 01/21/2023] Open
Abstract
Myeloid differentiation factor 2 (MD2) is a co-receptor of a classical proinflammatory protein TLR4 whose activation leads to neuroinflammation. It is widely accepted that TLR4 is expressed on the cell surface of microglia and astrocytes, and MD2 is expected to be expressed by these cells as well. However, our previous study showed that neurons from certain nuclei also expressed MD2. Whether MD2 is expressed by other brain nuclei is still unknown. It is the aim of the present study to map the distribution of MD2-positive cells in the adult mouse brain. Immunohistochemical staining against MD2 was completed to localize MD2-positive cells in the mouse brain by comparing the location of positive cells with the mouse brain atlas. MD2-positive cells were found in the majority of mouse brain nuclei with clusters of cells in the olfactory bulb, cortices, the red nucleus, and cranial nuclei. Subcortical nuclei had heterogeneous staining of MD2 with more prominent cells in the basolateral and the central amygdaloid nuclei. The ventral pallidum and the diagonal bands had positive cells with similar density and shape. Prominent cells were present in thalamic nuclei which were nearly homogeneous and in reticular formation of the brainstem where cells were dispersed with similar density. The hypothalamus had fewer outstanding cells compared with the thalamus. The red nucleus, the substantia nigra, and the ventral tegmental area in the pretectum had outstanding cells. Motor cranial nuclei also had outstanding MD2-positive cells, whereas raphe, sensory cranial, and deep cerebellar nuclei had MD2-positive cells with moderate density. The presence of MD2 in these nuclei may suggest the involvement of MD2 in their corresponding physiological functions.
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Affiliation(s)
- Zhen Li
- Clinical
Research Center for Anesthesiology and Perioperative Medicine, Shanghai
Fourth People’s Hospital, School of Medicine, Tongji University, Shanghai 200434, China
- Translational
Research Institute of Brain and Brain-Like Intelligence, Shanghai
Fourth People’s Hospital, School of Medicine, Tongji University, Shanghai 200434, China
- Department
of Anesthesiology and Perioperative Medicine, Shanghai Fourth People’s
Hospital, School of Medicine, Tongji University, Shanghai 200434, China
- Shanghai
Key Laboratory of Anesthesiology and Brain Functional Modulation, Shanghai 200434, China
| | - Aiwen Chen
- Clinical
Research Center for Anesthesiology and Perioperative Medicine, Shanghai
Fourth People’s Hospital, School of Medicine, Tongji University, Shanghai 200434, China
- Translational
Research Institute of Brain and Brain-Like Intelligence, Shanghai
Fourth People’s Hospital, School of Medicine, Tongji University, Shanghai 200434, China
- Department
of Anesthesiology and Perioperative Medicine, Shanghai Fourth People’s
Hospital, School of Medicine, Tongji University, Shanghai 200434, China
- Shanghai
Key Laboratory of Anesthesiology and Brain Functional Modulation, Shanghai 200434, China
| | - Hanxi Wan
- Clinical
Research Center for Anesthesiology and Perioperative Medicine, Shanghai
Fourth People’s Hospital, School of Medicine, Tongji University, Shanghai 200434, China
- Translational
Research Institute of Brain and Brain-Like Intelligence, Shanghai
Fourth People’s Hospital, School of Medicine, Tongji University, Shanghai 200434, China
- Department
of Anesthesiology and Perioperative Medicine, Shanghai Fourth People’s
Hospital, School of Medicine, Tongji University, Shanghai 200434, China
- Shanghai
Key Laboratory of Anesthesiology and Brain Functional Modulation, Shanghai 200434, China
| | - Xiaofei Gao
- Clinical
Research Center for Anesthesiology and Perioperative Medicine, Shanghai
Fourth People’s Hospital, School of Medicine, Tongji University, Shanghai 200434, China
- Translational
Research Institute of Brain and Brain-Like Intelligence, Shanghai
Fourth People’s Hospital, School of Medicine, Tongji University, Shanghai 200434, China
- Department
of Anesthesiology and Perioperative Medicine, Shanghai Fourth People’s
Hospital, School of Medicine, Tongji University, Shanghai 200434, China
- Shanghai
Key Laboratory of Anesthesiology and Brain Functional Modulation, Shanghai 200434, China
| | - Chunguang Li
- NICM
Health Research Institute, Western Sydney
University, Penrith, New South Wales 2751, Australia
| | - Lize Xiong
- Clinical
Research Center for Anesthesiology and Perioperative Medicine, Shanghai
Fourth People’s Hospital, School of Medicine, Tongji University, Shanghai 200434, China
- Translational
Research Institute of Brain and Brain-Like Intelligence, Shanghai
Fourth People’s Hospital, School of Medicine, Tongji University, Shanghai 200434, China
- Department
of Anesthesiology and Perioperative Medicine, Shanghai Fourth People’s
Hospital, School of Medicine, Tongji University, Shanghai 200434, China
- Shanghai
Key Laboratory of Anesthesiology and Brain Functional Modulation, Shanghai 200434, China
| | - Huazheng Liang
- Clinical
Research Center for Anesthesiology and Perioperative Medicine, Shanghai
Fourth People’s Hospital, School of Medicine, Tongji University, Shanghai 200434, China
- Translational
Research Institute of Brain and Brain-Like Intelligence, Shanghai
Fourth People’s Hospital, School of Medicine, Tongji University, Shanghai 200434, China
- Department
of Anesthesiology and Perioperative Medicine, Shanghai Fourth People’s
Hospital, School of Medicine, Tongji University, Shanghai 200434, China
- Shanghai
Key Laboratory of Anesthesiology and Brain Functional Modulation, Shanghai 200434, China
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16
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Worsley AL, Lui DH, Ntow-Boahene W, Song W, Good L, Tsui J. The importance of inflammation control for the treatment of chronic diabetic wounds. Int Wound J 2022. [PMID: 36564054 DOI: 10.1111/iwj.14048] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/21/2022] [Revised: 11/25/2022] [Accepted: 11/28/2022] [Indexed: 12/25/2022] Open
Abstract
Diabetic chronic wounds cause massive levels of patient suffering and economic problems worldwide. The state of chronic inflammation arises in response to a complex combination of diabetes mellitus-related pathophysiologies. Advanced treatment options are available; however, many wounds still fail to heal, exacerbating morbidity and mortality. This review describes the chronic inflammation pathophysiologies in diabetic ulcers and treatment options that may help address this dysfunction either directly or indirectly. We suggest that treatments to reduce inflammation within these complex wounds may help trigger healing.
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Affiliation(s)
- Anna L Worsley
- Royal Veterinary College, Department of Pathobiology and Population Sciences, London, UK.,UCL Centre for Biomaterials in Surgical Reconstruction and Regeneration, Department of Surgical Biotechnology, UCL Division of Surgery and Interventional Science, University College London, London, UK
| | - Dennis H Lui
- UCL Centre for Biomaterials in Surgical Reconstruction and Regeneration, Department of Surgical Biotechnology, UCL Division of Surgery and Interventional Science, University College London, London, UK
| | - Winnie Ntow-Boahene
- Royal Veterinary College, Department of Pathobiology and Population Sciences, London, UK.,UCL Centre for Biomaterials in Surgical Reconstruction and Regeneration, Department of Surgical Biotechnology, UCL Division of Surgery and Interventional Science, University College London, London, UK
| | - Wenhui Song
- UCL Centre for Biomaterials in Surgical Reconstruction and Regeneration, Department of Surgical Biotechnology, UCL Division of Surgery and Interventional Science, University College London, London, UK
| | - Liam Good
- Royal Veterinary College, Department of Pathobiology and Population Sciences, London, UK
| | - Janice Tsui
- UCL Centre for Biomaterials in Surgical Reconstruction and Regeneration, Department of Surgical Biotechnology, UCL Division of Surgery and Interventional Science, University College London, London, UK
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17
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Moriyama M, Konno M, Serizawa K, Yuzawa N, Majima Y, Hayashi I, Suzuki T, Kainoh M. Anti-pruritic effect of isothiocyanates: Potential involvement of toll-like receptor 3 signaling. Pharmacol Res Perspect 2022; 10:e01038. [PMID: 36507603 PMCID: PMC9741980 DOI: 10.1002/prp2.1038] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/06/2022] [Accepted: 11/16/2022] [Indexed: 12/14/2022] Open
Abstract
The innate immune system has an emerging role as a mediator of neuro-immune communication and a therapeutic target for itch. Toll-like receptor 3 (TLR3) plays an important role in itch, as shown in TLR3 knock-out mice. In this study, to evaluate effects of TLR3 inhibitors on histamine-independent itch, we used two kinds of isothiocyanate (ITC). Both phenethyl isothiocyanate (PEITC) and sulforaphane (SFN) inhibited Poly I:C (PIC)-induced signaling in the RAW264.7 cell line. We then investigated the anti-pruritic effect of these compounds on PIC- and chloroquine (CQ)-induced scratching behavior. PEITC and SFN both suppressed PIC-evoked scratching behavior in mice, and PEITC also inhibited CQ-induced acute itch. Finally, we examined the oxazolone-induced chronic itch model in mice. Surprisingly, oral dosing of both compounds suppressed scratching behaviors that were observed in mice. Our findings demonstrate that TLR3 is a critical mediator in acute and chronic itch transduction in mice and may be a promising therapeutic target for pruritus in human skin disorders. It is noteworthy that SFN has potential for use as an antipruritic as it is a phytochemical that is used as a supplement.
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Affiliation(s)
- Masaki Moriyama
- Pharmaceutical Research LaboratoriesToray Industries, Inc.KamakuraKanagawaJapan
| | - Mitsuhiro Konno
- Pharmaceutical Research LaboratoriesToray Industries, Inc.KamakuraKanagawaJapan
| | - Kanako Serizawa
- Pharmaceutical Research LaboratoriesToray Industries, Inc.KamakuraKanagawaJapan
| | - Natsumi Yuzawa
- Pharmaceutical Research LaboratoriesToray Industries, Inc.KamakuraKanagawaJapan
| | - Yuki Majima
- Pharmaceutical Research LaboratoriesToray Industries, Inc.KamakuraKanagawaJapan
| | - Ikuo Hayashi
- Pharmaceutical Research LaboratoriesToray Industries, Inc.KamakuraKanagawaJapan
| | - Tomohiko Suzuki
- Pharmaceutical Research LaboratoriesToray Industries, Inc.KamakuraKanagawaJapan
| | - Mie Kainoh
- Pharmaceutical Research LaboratoriesToray Industries, Inc.KamakuraKanagawaJapan
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18
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Systemic Lipopolysaccharide Challenge Induces Inflammatory Changes in Rat Dorsal Root Ganglia: An Ex Vivo Study. Int J Mol Sci 2022; 23:ijms232113124. [DOI: 10.3390/ijms232113124] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/05/2022] [Revised: 10/21/2022] [Accepted: 10/26/2022] [Indexed: 11/09/2022] Open
Abstract
Inflammatory processes within the peripheral nervous system (PNS) are associated with symptoms of hyperalgesia and allodynia. Pro-inflammatory mediators, such as cytokines or prostaglandins, modulate the excitability of nociceptive neurons, called peripheral sensitization. Here, we aimed to examine if previously reported effects of in vitro stimulation with lipopolysaccharide (LPS) on primary cell cultures of dorsal root ganglia (DRG) reflect changes in a model of LPS-induced systemic inflammation in vivo. Male rats were intraperitoneally injected with LPS (100 µg/kg) or saline. Effects of systemic inflammation on expression of inflammatory mediators, neuronal Ca2+ responses, and activation of inflammatory transcription factors in DRG were assessed. Systemic inflammation was accompanied by an enhanced expression of pro-inflammatory cytokines and cyclooxygenase-2 in lumbar DRG. In DRG primary cultures obtained from LPS-treated rats enhanced neuronal capsaicin-responses were detectable. Moreover, we found an increased activation of inflammatory transcription factors in cultured macrophages and neurons after an in vivo LPS challenge compared to saline controls. Overall, our study emphasizes the role of inflammatory processes in the PNS that may be involved in sickness-behavior-associated hyperalgesia induced by systemic LPS treatment. Moreover, we present DRG primary cultures as tools to study inflammatory processes on a cellular level, not only in vitro but also ex vivo.
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19
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García MM, Molina-Álvarez M, Rodríguez-Rivera C, Paniagua N, Quesada E, Uranga JA, Rodríguez-Franco MI, Pascual D, Goicoechea C. Antinociceptive and modulatory effect of pathoplastic changes in spinal glia of a TLR4/CD14 blocking molecule in two models of pain in rat. Biomed Pharmacother 2022; 150:112986. [PMID: 35462333 DOI: 10.1016/j.biopha.2022.112986] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/08/2022] [Revised: 04/02/2022] [Accepted: 04/14/2022] [Indexed: 11/02/2022] Open
Abstract
The role of spinal glia in the development and maintenance of chronic pain has become over the last years a subject of increasing interest. In this regard, toll-like receptor 4 (TLR4) signaling has been proposed as a major trigger mechanism. Hence, in this study we explored the implications of TLR4 inhibition in the periphery and primarily in the CNS, focusing on the impact this inhibition renders in pain development and glia activation in the dorsal horn in two models of pain. Making use of a synthetic cluster of differentiation 14 (CD14)/TLR4 antagonist, the effect of TLR4 blockade on tactile allodynia and heat hyperalgesia was evaluated in osteoarthritic and postoperative rat models. An in vitro parallel artificial membrane permeation assay was performed to determine the proneness of the drug to permeate the blood-brain barrier prior to systemic and central administration. Findings suggest a dominant role of peripheral TLR4 in the model of incisional pain, whilst both peripheral and central TLR4 seem to be responsible for osteoarthritic pain. That is, central and peripheral TLR4 may be differently involved in the etiopathology of diverse types of pain what potentially seems a promising approach in the management of pain.
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Affiliation(s)
- Miguel M García
- Area of Pharmacology and Nutrition and Bromatology, Department of Basic Health Sciences, School of Health Sciences, Universidad Rey Juan Carlos, High Performance Experimental Pharmacology Research Group, Universidad Rey Juan Carlos (PHARMAKOM), Madrid, Spain; Unidad Asociada I+D+i Instituto de Química Médica (IQM-CSIC)-URJC, Madrid, Spain
| | - Miguel Molina-Álvarez
- Area of Pharmacology and Nutrition and Bromatology, Department of Basic Health Sciences, School of Health Sciences, Universidad Rey Juan Carlos, High Performance Experimental Pharmacology Research Group, Universidad Rey Juan Carlos (PHARMAKOM), Madrid, Spain; Unidad Asociada I+D+i Instituto de Química Médica (IQM-CSIC)-URJC, Madrid, Spain
| | - Carmen Rodríguez-Rivera
- Area of Pharmacology and Nutrition and Bromatology, Department of Basic Health Sciences, School of Health Sciences, Universidad Rey Juan Carlos, High Performance Experimental Pharmacology Research Group, Universidad Rey Juan Carlos (PHARMAKOM), Madrid, Spain; Unidad Asociada I+D+i Instituto de Química Médica (IQM-CSIC)-URJC, Madrid, Spain
| | - Nancy Paniagua
- Area of Pharmacology and Nutrition and Bromatology, Department of Basic Health Sciences, School of Health Sciences, Universidad Rey Juan Carlos, High Performance Experimental Pharmacology Research Group, Universidad Rey Juan Carlos (PHARMAKOM), Madrid, Spain; Unidad Asociada I+D+i Instituto de Química Médica (IQM-CSIC)-URJC, Madrid, Spain
| | - Ernesto Quesada
- Instituto de Química Médica, Consejo Superior de Investigaciones Científicas (IQM-CSIC), Madrid, Spain; Unidad Asociada I+D+i Instituto de Química Médica (IQM-CSIC)-URJC, Madrid, Spain
| | - José Antonio Uranga
- Area of Histology, Department of Basic Health Sciences, School of Health Sciences, Universidad Rey Juan Carlos, High Performance Research Group in Physiopathology and Pharmacology of the Digestive System, Universidad Rey Juan Carlos (NEUGUT), Madrid, Spain
| | | | - David Pascual
- Area of Pharmacology and Nutrition and Bromatology, Department of Basic Health Sciences, School of Health Sciences, Universidad Rey Juan Carlos, High Performance Experimental Pharmacology Research Group, Universidad Rey Juan Carlos (PHARMAKOM), Madrid, Spain; Unidad Asociada I+D+i Instituto de Química Médica (IQM-CSIC)-URJC, Madrid, Spain.
| | - Carlos Goicoechea
- Area of Pharmacology and Nutrition and Bromatology, Department of Basic Health Sciences, School of Health Sciences, Universidad Rey Juan Carlos, High Performance Experimental Pharmacology Research Group, Universidad Rey Juan Carlos (PHARMAKOM), Madrid, Spain; Unidad Asociada I+D+i Instituto de Química Médica (IQM-CSIC)-URJC, Madrid, Spain
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20
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Küçük M, Aksoy U, Özer Şehirli A. Possible protective effects of the Bmal1 gene and melatonin on the prognosis of apical periodontitis. Med Hypotheses 2022. [DOI: 10.1016/j.mehy.2022.110806] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
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21
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Acioglu C, Heary RF, Elkabes S. Roles of neuronal toll-like receptors in neuropathic pain and central nervous system injuries and diseases. Brain Behav Immun 2022; 102:163-178. [PMID: 35176442 DOI: 10.1016/j.bbi.2022.02.016] [Citation(s) in RCA: 18] [Impact Index Per Article: 9.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 11/02/2021] [Revised: 01/12/2022] [Accepted: 02/11/2022] [Indexed: 12/12/2022] Open
Abstract
Toll-like receptors (TLRs) are innate immune receptors that are expressed in immune cells as well as glia and neurons of the central and peripheral nervous systems. They are best known for their role in the host defense in response to pathogens and for the induction of inflammation in infectious and non-infectious diseases. In the central nervous system (CNS), TLRs modulate glial and neuronal functions as well as innate immunity and neuroinflammation under physiological or pathophysiological conditions. The majority of the studies on TLRs in CNS pathologies investigated their overall contribution without focusing on a particular cell type, or they analyzed TLRs in glia and infiltrating immune cells in the context of neuroinflammation and cellular activation. The role of neuronal TLRs in CNS diseases and injuries has received little attention and remains underappreciated. The primary goal of this review is to summarize findings demonstrating the pivotal and unique roles of neuronal TLRs in neuropathic pain, Alzheimer's disease, Parkinson's disease and CNS injuries. We discuss how the current findings warrant future investigations to better define the specific contributions of neuronal TLRs to these pathologies. We underline the paucity of information regarding the role of neuronal TLRs in other neurodegenerative, demyelinating, and psychiatric diseases. We draw attention to the importance of broadening research on neuronal TLRs in view of emerging evidence demonstrating their distinctive functional properties.
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Affiliation(s)
- Cigdem Acioglu
- The Reynolds Family Spine Laboratory, Department of Neurosurgery, New Jersey Medical School, Rutgers, The State University of New Jersey, Newark, NJ 07103, United States
| | - Robert F Heary
- Department of Neurological Surgery, Hackensack Meridian School of Medicine, Mountainside Medical Center, Montclair, NJ 07042, United States
| | - Stella Elkabes
- The Reynolds Family Spine Laboratory, Department of Neurosurgery, New Jersey Medical School, Rutgers, The State University of New Jersey, Newark, NJ 07103, United States.
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22
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Mustafa S, Evans S, Barry B, Barratt D, Wang Y, Lin C, Wang X, Hutchinson MR. Toll-Like Receptor 4 in Pain: Bridging Molecules-to-Cells-to-Systems. Handb Exp Pharmacol 2022; 276:239-273. [PMID: 35434749 DOI: 10.1007/164_2022_587] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/14/2023]
Abstract
Pain impacts the lives of billions of people around the world - both directly and indirectly. It is complex and transcends beyond an unpleasant sensory experience to encompass emotional experiences. To date, there are no successful treatments for sufferers of chronic pain. Although opioids do not provide any benefit to chronic pain sufferers, they are still prescribed, often resulting in more complications such as hyperalgesia and dependence. In order to develop effective and safe medications to manage, and perhaps even treat pain, it is important to evaluate novel contributors to pain pathologies. As such, in this chapter we review the role of Toll-like receptor 4, a receptor of the innate immune system, that continues to gain substantial attention in the field of pain research. Positioned in the nexus of the neuro and immune systems, TLR4 may provide one of the missing pieces in understanding the complexities of pain. Here we consider how TLR4 enables a mechanistical understanding of pain as a multidimensional biopsychosocial state from molecules to cells to systems and back again.
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Affiliation(s)
- Sanam Mustafa
- Adelaide Medical School, The University of Adelaide, Adelaide, SA, Australia.
- Australian Research Council Centre of Excellence for Nanoscale BioPhotonics, The University of Adelaide, Adelaide, SA, Australia.
| | - Samuel Evans
- Adelaide Medical School, The University of Adelaide, Adelaide, SA, Australia
| | - Benjamin Barry
- Adelaide Medical School, The University of Adelaide, Adelaide, SA, Australia
| | - Daniel Barratt
- Adelaide Medical School, The University of Adelaide, Adelaide, SA, Australia
| | - Yibo Wang
- Laboratory of Chemical Biology, Changchun Institute of Applied Chemistry, Chinese Academy of Sciences, Changchun, Jilin, China
| | - Cong Lin
- Laboratory of Chemical Biology, Changchun Institute of Applied Chemistry, Chinese Academy of Sciences, Changchun, Jilin, China
| | - Xiaohui Wang
- Laboratory of Chemical Biology, Changchun Institute of Applied Chemistry, Chinese Academy of Sciences, Changchun, Jilin, China
- School of Applied Chemistry and Engineering, University of Science and Technology of China, Hefei, Anhui, China
| | - Mark R Hutchinson
- Adelaide Medical School, The University of Adelaide, Adelaide, SA, Australia
- Australian Research Council Centre of Excellence for Nanoscale BioPhotonics, The University of Adelaide, Adelaide, SA, Australia
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23
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Seizer L, Rahimi S, Santos-Sierra S, Drexel M. Expression of toll like receptor 8 (TLR8) in specific groups of mouse hippocampal interneurons. PLoS One 2022; 17:e0267860. [PMID: 35507634 PMCID: PMC9067651 DOI: 10.1371/journal.pone.0267860] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/01/2021] [Accepted: 04/16/2022] [Indexed: 11/18/2022] Open
Abstract
Toll-like receptors (TLR) are one of the main constituents of the innate immune system in mammals. They can detect conserved microbial structures (pathogen-associated molecular patterns) and host-derived ligands that are produced during cellular stress and damage (danger-associated molecular patterns) and may then initiate an intracellular signaling cascade leading to the expression of pro-inflammatory cytokines and immediate immune responses. Some TLR (TLR1, 2, 4, 5, and 6) are expressed on the cell surface while others (TLR3, 7, 8 and 9) are present on the surface of endosomes and their ligands require internalization before recognition is possible. Several TLR have also been detected in neurons where they may serve functions that are not related to immune responses. TLR2, 3, and 4 have been described in cortical neurons and, for TLR4, a seizure-promoting role in epilepsies associated with inflammation has been shown. TLR3, 7, and 8 expressed in neurons seem to influence the growth or withdrawal of neurites and robust activation of TLR8 in neurons may even induce neuronal death. The goal of the current study was to investigate the expression of TLR8 in the hippocampus of mice during postnatal development and in adulthood. We focused on three functionally distinct groups of GABAergic interneurons characterized by the expression of the molecular markers parvalbumin, somatostatin, or calretinin, and we applied double fluorescence immunohistochemistry and cell counts to quantify co-expression of TLR8 in the three groups of GABA-interneurons across hippocampal subregions. We found subregion-specific differences in the expression of TLR8 in these interneurons. During postnatal development, TLR8 was detected only in mice older than P5. While only a small fraction of hippocampal calretinin-positive interneurons expressed TLR8, most parvalbumin-positive interneurons in all hippocampal subregions co-expressed TLR8. Somatostatin-positive interneurons co-expressing TLR8 were mainly present in hippocampal sector CA3 but rare in the dentate gyrus and CA1. High expression of TLR8 in parvalbumin-interneurons may contribute to their high vulnerability in human temporal lobe epilepsy.
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Affiliation(s)
- Lennart Seizer
- Department of Pharmacology, Medical University of Innsbruck, Innsbruck, Austria
- Institute of Psychology, University of Innsbruck, Innsbruck, Austria
| | - Sadegh Rahimi
- Department of Pharmacology, Medical University of Innsbruck, Innsbruck, Austria
| | | | - Meinrad Drexel
- Department of Pharmacology, Medical University of Innsbruck, Innsbruck, Austria
- * E-mail:
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Sansores-España LD, Melgar-Rodríguez S, Olivares-Sagredo K, Cafferata EA, Martínez-Aguilar VM, Vernal R, Paula-Lima AC, Díaz-Zúñiga J. Oral-Gut-Brain Axis in Experimental Models of Periodontitis: Associating Gut Dysbiosis With Neurodegenerative Diseases. FRONTIERS IN AGING 2021; 2:781582. [PMID: 35822001 PMCID: PMC9261337 DOI: 10.3389/fragi.2021.781582] [Citation(s) in RCA: 23] [Impact Index Per Article: 7.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 09/22/2021] [Accepted: 11/08/2021] [Indexed: 12/12/2022]
Abstract
Periodontitis is considered a non-communicable chronic disease caused by a dysbiotic microbiota, which generates a low-grade systemic inflammation that chronically damages the organism. Several studies have associated periodontitis with other chronic non-communicable diseases, such as cardiovascular or neurodegenerative diseases. Besides, the oral bacteria considered a keystone pathogen, Porphyromonas gingivalis, has been detected in the hippocampus and brain cortex. Likewise, gut microbiota dysbiosis triggers a low-grade systemic inflammation, which also favors the risk for both cardiovascular and neurodegenerative diseases. Recently, the existence of an axis of Oral-Gut communication has been proposed, whose possible involvement in the development of neurodegenerative diseases has not been uncovered yet. The present review aims to compile evidence that the dysbiosis of the oral microbiota triggers changes in the gut microbiota, which creates a higher predisposition for the development of neuroinflammatory or neurodegenerative diseases.The Oral-Gut-Brain axis could be defined based on anatomical communications, where the mouth and the intestine are in constant communication. The oral-brain axis is mainly established from the trigeminal nerve and the gut-brain axis from the vagus nerve. The oral-gut communication is defined from an anatomical relation and the constant swallowing of oral bacteria. The gut-brain communication is more complex and due to bacteria-cells, immune and nervous system interactions. Thus, the gut-brain and oral-brain axis are in a bi-directional relationship. Through the qualitative analysis of the selected papers, we conclude that experimental periodontitis could produce both neurodegenerative pathologies and intestinal dysbiosis, and that periodontitis is likely to induce both conditions simultaneously. The severity of the neurodegenerative disease could depend, at least in part, on the effects of periodontitis in the gut microbiota, which could strengthen the immune response and create an injurious inflammatory and dysbiotic cycle. Thus, dementias would have their onset in dysbiotic phenomena that affect the oral cavity or the intestine. The selected studies allow us to speculate that oral-gut-brain communication exists, and bacteria probably get to the brain via trigeminal and vagus nerves.
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Affiliation(s)
- Luis Daniel Sansores-España
- Periodontal Biology Laboratory, Faculty of Dentistry, University of Chile, Santiago, Chile
- Faculty of Dentistry, Autonomous University of Yucatán, Mérida, México
| | | | | | - Emilio A. Cafferata
- Department of Periodontology, School of Dentistry, Universidad Científica Del Sur, Lima, Perú
| | | | - Rolando Vernal
- Periodontal Biology Laboratory, Faculty of Dentistry, University of Chile, Santiago, Chile
| | - Andrea Cristina Paula-Lima
- Biomedical Neuroscience Institute, Faculty of Medicine, Universidad de Chile, Santiago, Chile
- Department of Neuroscience, Faculty of Medicine, Universidad de Chile, Santiago, Chile
- Institute for Research in Dental Sciences, Faculty of Dentistry, Universidad de Chile, Santiago, Chile
| | - Jaime Díaz-Zúñiga
- Periodontal Biology Laboratory, Faculty of Dentistry, University of Chile, Santiago, Chile
- Department of Medicine, Faculty of Medicine, University of Atacama, Copiapó, Chile
- *Correspondence: Jaime Díaz-Zúñiga, ,
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25
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Lee PR, Lee JH, Park JM, Oh SB. Upregulation of Toll-like Receptor 2 in Dental Primary Afferents Following Pulp Injury. Exp Neurobiol 2021; 30:329-340. [PMID: 34737238 PMCID: PMC8572661 DOI: 10.5607/en21018] [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: 06/19/2021] [Revised: 10/23/2021] [Accepted: 10/24/2021] [Indexed: 11/19/2022] Open
Abstract
Pulpitis (toothache) is a painful inflammation of the dental pulp and is a prevalent problem throughout the world. This pulpal inflammation occurs in the cells inside the dental pulp, which have host defense mechanisms to combat oral microorganisms invading the pulp space of exposed teeth. This innate immunity has been well studied, with a focus on Toll-like receptors (TLRs). The function of TLR4, activated by Gram-negative bacteria, has been demonstrated in trigeminal ganglion (TG) neurons for dental pain. Although Gram-positive bacteria predominate in the teeth of patients with caries and pulpitis, the role of TLR2, which is activated by Gram-positive bacteria, is poorly understood in dental primary afferent (DPA) neurons that densely innervate the dental pulp. Using Fura-2 based Ca2+ imaging, we observed reproducible intracellular Ca2+ responses induced by Pam3CSK4 and Pam2CSK4 (TLR2-specific agonists) in TG neurons of adult wild-type (WT) mice. The response was completely abolished in TLR2 knock-out (KO) mice. Single-cell RT-PCR detected Tlr2 mRNA in DPA neurons labeled with fluorescent retrograde tracers from the upper molars. Using the mouse pulpitis model, real-time RT-PCR revealed that Tlr2 and inflammatory-related molecules were upregulated in injured TG, compared to non-injured TG, from WT mice, but not from TLR2 KO mice. TLR2 protein expression was also upregulated in injured DPA neurons, and the change was corresponded with a significant increase in calcitonin gene-related peptide (CGRP) expression. Our results provide a better molecular understanding of pulpitis by revealing the potential contribution of TLR2 to pulpal inflammatory pain.
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Affiliation(s)
- Pa Reum Lee
- Department of Neurobiology and Physiology, School of Dentistry and Dental Research Institute, Seoul National University, Seoul 03080, Korea
| | - Jin-Hee Lee
- Department of Neurobiology and Physiology, School of Dentistry and Dental Research Institute, Seoul National University, Seoul 03080, Korea
| | - Ji Min Park
- Department of Neurobiology and Physiology, School of Dentistry and Dental Research Institute, Seoul National University, Seoul 03080, Korea
| | - Seog Bae Oh
- Department of Neurobiology and Physiology, School of Dentistry and Dental Research Institute, Seoul National University, Seoul 03080, Korea
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26
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Adhikarla SV, Jha NK, Goswami VK, Sharma A, Bhardwaj A, Dey A, Villa C, Kumar Y, Jha SK. TLR-Mediated Signal Transduction and Neurodegenerative Disorders. Brain Sci 2021; 11:brainsci11111373. [PMID: 34827372 PMCID: PMC8615980 DOI: 10.3390/brainsci11111373] [Citation(s) in RCA: 17] [Impact Index Per Article: 5.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/22/2021] [Revised: 10/16/2021] [Accepted: 10/16/2021] [Indexed: 11/16/2022] Open
Abstract
A special class of proteins called Toll-like receptors (TLRs) are an essential part of the innate immune system, connecting it to the adaptive immune system. There are 10 different Toll-Like Receptors that have been identified in human beings. TLRs are part of the central nervous system (CNS), showing that the CNS is capable of the immune response, breaking the long-held belief of the brain's "immune privilege" owing to the blood-brain barrier (BBB). These Toll-Like Receptors are present not just on the resident macrophages of the central nervous system but are also expressed by the neurons to allow them for the production of proinflammatory agents such as interferons, cytokines, and chemokines; the activation and recruitment of glial cells; and their participation in neuronal cell death by apoptosis. This study is focused on the potential roles of various TLRs in various neurodegenerative diseases such as Parkinson's disease (PD) and Alzheimer's disease (AD), namely TLR2, TLR3, TLR4, TLR7, and TLR9 in AD and PD in human beings and a mouse model.
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Affiliation(s)
- Shashank Vishwanath Adhikarla
- Department of Biological Sciences and Engineering, Netaji Subhas University of Technology (Formerly NSIT, University of Delhi), New Delhi 110078, India;
| | - Niraj Kumar Jha
- Department of Biotechnology, School of Engineering & Technology (SET), Sharda University, Greater Noida 201310, India; (N.K.J.); (A.B.)
| | - Vineet Kumar Goswami
- Department of Biotechnology, Delhi Technological University, Delhi 110042, India;
- Department of Science and Engineering, Novel Global Community Educational Foundation, Hebersham 2770, Australia;
| | - Ankur Sharma
- Department of Science and Engineering, Novel Global Community Educational Foundation, Hebersham 2770, Australia;
- Department of Life Science, School of Basic Science & Research (SBSR), Sharda University, Greater Noida 201310, India
| | - Anuradha Bhardwaj
- Department of Biotechnology, School of Engineering & Technology (SET), Sharda University, Greater Noida 201310, India; (N.K.J.); (A.B.)
| | - Abhijit Dey
- Department of Life Sciences, Presidency University, 86/1 College Street, Kolkata 700073, India;
| | - Chiara Villa
- School of Medicine and Surgery, University of Milano-Bicocca, 20900 Monza, Italy;
| | - Yatender Kumar
- Department of Biological Sciences and Engineering, Netaji Subhas University of Technology (Formerly NSIT, University of Delhi), New Delhi 110078, India;
- Correspondence: (Y.K.); (S.K.J.)
| | - Saurabh Kumar Jha
- Department of Biotechnology, School of Engineering & Technology (SET), Sharda University, Greater Noida 201310, India; (N.K.J.); (A.B.)
- Department of Science and Engineering, Novel Global Community Educational Foundation, Hebersham 2770, Australia;
- Correspondence: (Y.K.); (S.K.J.)
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27
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Ferreira-Gomes J, Garcia MM, Nascimento D, Almeida L, Quesada E, Castro-Lopes JM, Pascual D, Goicoechea C, Neto FL. TLR4 Antagonism Reduces Movement-Induced Nociception and ATF-3 Expression in Experimental Osteoarthritis. J Pain Res 2021; 14:2615-2627. [PMID: 34466029 PMCID: PMC8403032 DOI: 10.2147/jpr.s317877] [Citation(s) in RCA: 7] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/04/2021] [Accepted: 07/29/2021] [Indexed: 01/13/2023] Open
Abstract
Introduction Toll-like receptor 4 (TLR4) is a pattern recognition receptor involved in the detection of pathogen-associated molecular patterns (PAMPs), but also a "danger-sensing" receptor that recognizes host-derived endogenous molecules called damage-associated molecular patterns (DAMPs). The involvement of TLR4 in rheumatic diseases is becoming evident, as well as its potential role as a target for therapeutic intervention. Moreover, increasing evidence also suggests that TLR4 is implicated in chronic pain states. Thus, in this study, we evaluated whether a systemic administration of a synthetic antagonist of TLR4 (TLR4-A1) could decrease nociception and cartilage degradation in experimental osteoarthritis (OA). Furthermore, as the activation transcription factor (ATF)-3 serves as a negative regulator for TLR4-stimulated inflammatory response, we also evaluated the effect of TLR4 inhibition on ATF-3 expression in primary afferent neurons at the dorsal root ganglia (DRG). Methods OA was induced in adult male Wistar rats through an intra-articular injection of 2 mg of sodium mono-iodoacetate (MIA) into the left knee. From days 14 to 28 after OA induction, animals received an intraperitoneal injection of either TLR4-A1 (10 mg/kg) or vehicle. Movement- and loading-induced nociception was evaluated in all animals, by the Knee-Bend and CatWalk tests, before and at several time-points after TLR4-A1/vehicle administration. Immunofluorescence for TLR4 and ATF-3 was performed in L3-L5 DRG. Knee joints were processed for histopathological evaluation. Results Administration of TLR4-A1 markedly reduced movement-induced nociception in OA animals, particularly in the Knee-Bend test. Moreover, the increase of ATF-3 expression observed in DRG of OA animals was significantly reduced by TLR4-A1. However, no effect was observed in cartilage loss nor in the neuronal cytoplasmic expression of TLR4 upon antagonist administration. Conclusion The TLR4 antagonist administration possibly interrupts the TLR4 signalling cascade, thus decreasing the neurotoxic environment at the joint, which leads to a reduction in ATF-3 expression and in nociception associated with experimental OA.
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Affiliation(s)
- Joana Ferreira-Gomes
- i3S - Instituto de Investigação e Inovação em Saúde, Universidade do Porto, Porto, Portugal.,Departamento de Biomedicina, Faculdade de Medicina da Universidade do Porto, Porto, Portugal
| | - Miguel M Garcia
- Area of Pharmacology, Nutrition and Bromatology, Department of Basic Health Sciences, Universidad Rey Juan Carlos, Unidad Asociada I+D+i Instituto de Química Médica (IQM) CSIC-URJC, Madrid, Spain.,High Performance Experimental Pharmacology research group, Universidad Rey Juan Carlos (PHARMAKOM), Alcorcón, Spain.,Grupo de Excelencia Investigadora URJC-Banco de Santander-Grupo multidisciplinar de investigación y tratamiento del dolor (i+DOL), Alcorcón, Spain
| | - Diana Nascimento
- i3S - Instituto de Investigação e Inovação em Saúde, Universidade do Porto, Porto, Portugal.,Departamento de Biomedicina, Faculdade de Medicina da Universidade do Porto, Porto, Portugal
| | - Lígia Almeida
- i3S - Instituto de Investigação e Inovação em Saúde, Universidade do Porto, Porto, Portugal.,Departamento de Biomedicina, Faculdade de Medicina da Universidade do Porto, Porto, Portugal
| | - Ernesto Quesada
- Area of Pharmacology, Nutrition and Bromatology, Department of Basic Health Sciences, Universidad Rey Juan Carlos, Unidad Asociada I+D+i Instituto de Química Médica (IQM) CSIC-URJC, Madrid, Spain.,Grupo de Excelencia Investigadora URJC-Banco de Santander-Grupo multidisciplinar de investigación y tratamiento del dolor (i+DOL), Alcorcón, Spain
| | - José Manuel Castro-Lopes
- i3S - Instituto de Investigação e Inovação em Saúde, Universidade do Porto, Porto, Portugal.,Departamento de Biomedicina, Faculdade de Medicina da Universidade do Porto, Porto, Portugal
| | - David Pascual
- Area of Pharmacology, Nutrition and Bromatology, Department of Basic Health Sciences, Universidad Rey Juan Carlos, Unidad Asociada I+D+i Instituto de Química Médica (IQM) CSIC-URJC, Madrid, Spain.,High Performance Experimental Pharmacology research group, Universidad Rey Juan Carlos (PHARMAKOM), Alcorcón, Spain.,Grupo de Excelencia Investigadora URJC-Banco de Santander-Grupo multidisciplinar de investigación y tratamiento del dolor (i+DOL), Alcorcón, Spain
| | - Carlos Goicoechea
- Area of Pharmacology, Nutrition and Bromatology, Department of Basic Health Sciences, Universidad Rey Juan Carlos, Unidad Asociada I+D+i Instituto de Química Médica (IQM) CSIC-URJC, Madrid, Spain.,High Performance Experimental Pharmacology research group, Universidad Rey Juan Carlos (PHARMAKOM), Alcorcón, Spain.,Grupo de Excelencia Investigadora URJC-Banco de Santander-Grupo multidisciplinar de investigación y tratamiento del dolor (i+DOL), Alcorcón, Spain
| | - Fani Lourença Neto
- i3S - Instituto de Investigação e Inovação em Saúde, Universidade do Porto, Porto, Portugal.,Departamento de Biomedicina, Faculdade de Medicina da Universidade do Porto, Porto, Portugal
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28
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Wang H, Huang M, Wang W, Zhang Y, Ma X, Luo L, Xu X, Xu L, Shi H, Xu Y, Wang A, Xu T. Microglial TLR4-induced TAK1 phosphorylation and NLRP3 activation mediates neuroinflammation and contributes to chronic morphine-induced antinociceptive tolerance. Pharmacol Res 2021; 165:105482. [PMID: 33549727 DOI: 10.1016/j.phrs.2021.105482] [Citation(s) in RCA: 24] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 12/13/2020] [Revised: 02/02/2021] [Accepted: 02/02/2021] [Indexed: 01/04/2023]
Abstract
BACKGROUND AND PURPOSE The aim of this work was to investigate the role and signal transduction of toll-like receptor 4 (TLR4), TGF-β-activated kinase 1 (TAK1) and nod-like receptor protein 3 (NLRP3) in microglial in the development of morphine-induced antinociceptive tolerance. METHODS TLR4 and NLRP3 knockout mice and 5Z-7-oxozeaeno (a selective inhibitor against TAK1 activity) were used to observe their effect on the development of morphine tolerance. Intrathecal injections of morphine (0.75 mg/kg once daily for 7 days) were used to establish anti-nociceptive tolerance, which was measured by the tail-flick test. Spinal TLR4, TAK1, and NLRP3 expression levels and phosphorylation of TAK1 were evaluated by Western blotting and immunofluorescence. RESULTS Repeated treatment with morphine increased total expression of spinal TLR4, TAK1, and NLRP3 and phosphorylation of TAK1 in wild-type mice. TLR4 knockout attenuated morphine-induced tolerance and inhibited the chronic morphine-induced increase in NLRP3 and phosphorylation of TAK1. Compared with controls, mice that received 5Z-7-oxozeaenol showed decreased development of morphine tolerance and inhibition on repeated morphine-induced increase of NLRP3 but not TLR4. NLRP3 knockout mice showed resistance to morphine-induced analgesic tolerance with no effect on chronic morphine-induced expression of TLR4 and TAK1. TLR4, TAK1, and NLRP3 were collectively co-localized together and with the microglia marker Iba1. CONCLUSIONS Microglial TLR4 regulates TAK1 expression and phosphorylation and results in NLRP3 activation contributes to the development of morphine tolerance through regulating neuroinflammation. Targeting TLR4-TAK1-NLRP3 signaling to regulate neuro-inflammation will be alternative therapeutics and strategies for chronic morphine-induced antinociceptive tolerance.
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Affiliation(s)
- Haiyan Wang
- Department of Anesthesiology, Tongzhou People's Hospital, Nantong 226300, China; Department of Anesthesiology and Pain Clinic, Shanghai Jiao Tong University Affiliated Sixth People's Hospital, 600 Yi Shan Road, Shanghai 200233, China
| | - Min Huang
- Department of Anesthesiology and Pain Clinic, Shanghai Jiao Tong University Affiliated Sixth People's Hospital, 600 Yi Shan Road, Shanghai 200233, China
| | - Wenying Wang
- Department of Anesthesiology and Pain Clinic, Shanghai Jiao Tong University Affiliated Sixth People's Hospital, 600 Yi Shan Road, Shanghai 200233, China
| | - Yu Zhang
- Department of Anesthesiology and Pain Clinic, Shanghai Jiao Tong University Affiliated Sixth People's Hospital, 600 Yi Shan Road, Shanghai 200233, China
| | - Xiaqing Ma
- Department of Anesthesiology and Pain Clinic, Shanghai Jiao Tong University Affiliated Sixth People's Hospital, 600 Yi Shan Road, Shanghai 200233, China
| | - Limin Luo
- Department of Anesthesiology and Pain Clinic, Shanghai Jiao Tong University Affiliated Sixth People's Hospital, 600 Yi Shan Road, Shanghai 200233, China
| | - Xiaotao Xu
- Department of Anesthesiology and Pain Clinic, Shanghai Jiao Tong University Affiliated Sixth People's Hospital, 600 Yi Shan Road, Shanghai 200233, China
| | - Liang Xu
- Heart Health Center, East Hospital, Tongji University School of Medicine, Shanghai 200120, China
| | - Haibo Shi
- Shanghai Key Laboratory of Sleep Disordered Breathing, Shanghai 200233, China
| | - Yongming Xu
- Department of Anesthesiology and Pain Clinic, Shanghai Jiao Tong University Affiliated Sixth People's Hospital, 600 Yi Shan Road, Shanghai 200233, China.
| | - Aizhong Wang
- Department of Anesthesiology and Pain Clinic, Shanghai Jiao Tong University Affiliated Sixth People's Hospital, 600 Yi Shan Road, Shanghai 200233, China.
| | - Tao Xu
- Department of Anesthesiology, Tongzhou People's Hospital, Nantong 226300, China; Department of Anesthesiology and Pain Clinic, Shanghai Jiao Tong University Affiliated Sixth People's Hospital, 600 Yi Shan Road, Shanghai 200233, China.
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29
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Livshits G, Kalinkovich A. Specialized, pro-resolving mediators as potential therapeutic agents for alleviating fibromyalgia symptomatology. PAIN MEDICINE 2021; 23:977-990. [PMID: 33565588 DOI: 10.1093/pm/pnab060] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/19/2022]
Abstract
OBJECTIVE To present a hypothesis on a novel strategy in the treatment of fibromyalgia (FM). DESIGN A narrative review. SETTING FM as a disease remains a challenging concept for numerous reasons, including undefined etiopathogenesis, unclear triggers and unsuccessful treatment modalities. We hypothesize that the inflammatome, the entire set of molecules involved in inflammation, acting as a common pathophysiological instrument of gut dysbiosis, sarcopenia, and neuroinflammation, is one of the major mechanisms underlying FM pathogenesis. In this setup, dysbiosis is proposed as the primary trigger of the inflammatome, sarcopenia as the peripheral nociceptive source, and neuroinflammation as the central mechanism of pain sensitization, transmission and symptomatology of FM. Whereas neuroinflammation is highly-considered as a critical deleterious element in FM pathogenesis, the presumed pathogenic roles of sarcopenia and systemic inflammation remain controversial. Nevertheless, sarcopenia-associated processes and dysbiosis have been recently detected in FM individuals. The prevalence of pro-inflammatory factors in the cerebrospinal fluid and blood has been repeatedly observed in FM individuals, supporting an idea on the role of inflammatome in FM pathogenesis. As such, failed inflammation resolution might be one of the underlying pathogenic mechanisms. In accordance, the application of specialized, inflammation pro-resolving mediators (SPMs) seems most suitable for this goal. CONCLUSIONS The capability of various SPMs to prevent and attenuate pain has been repeatedly demonstrated in laboratory animal experiments. Since SPMs suppress inflammation in a manner that does not compromise host defense, they could be attractive and safe candidates for the alleviation of FM symptomatology, probably in combination with anti-dysbiotic medicine.
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Affiliation(s)
- Gregory Livshits
- Adelson School of Medicine, Ariel University, Ariel, Israel.,Department of Anatomy and Anthropology, Sackler Faculty of Medicine, Tel-Aviv University, Tel-Aviv, Israel
| | - Alexander Kalinkovich
- Department of Anatomy and Anthropology, Sackler Faculty of Medicine, Tel-Aviv University, Tel-Aviv, Israel
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30
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Li Y, Jiang Q, Wang L. Appetite Regulation of TLR4-Induced Inflammatory Signaling. Front Endocrinol (Lausanne) 2021; 12:777997. [PMID: 34899611 PMCID: PMC8664591 DOI: 10.3389/fendo.2021.777997] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 09/16/2021] [Accepted: 11/04/2021] [Indexed: 12/20/2022] Open
Abstract
Appetite is the basis for obtaining food and maintaining normal metabolism. Toll-like receptor 4 (TLR4) is an important receptor expressed in the brain that induces inflammatory signaling after activation. Inflammation is considered to affect the homeostatic and non-homeostatic systems of appetite, which are dominated by hypothalamic and mesolimbic dopamine signaling. Although the pathological features of many types of inflammation are known, their physiological functions in appetite are largely unknown. This review mainly addresses several key issues, including the structures of the homeostatic and non-homeostatic systems. In addition, the mechanism by which TLR4-induced inflammatory signaling contributes to these two systems to regulate appetite is also discussed. This review will provide potential opportunities to develop new therapeutic interventions that control appetite under inflammatory conditions.
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Affiliation(s)
- Yongxiang Li
- Guangdong Provincial Key Laboratory of Animal Nutrition Control, South China Agricultural University, Guangzhou, China
- National Engineering Research Center for Breeding Swine Industry, College of Animal Science, South China Agricultural University, Guangzhou, China
- Children’s Nutrition Research Center, Department of Pediatrics, Baylor College of Medicine, Houston, TX, United States
| | - Qingyan Jiang
- Guangdong Provincial Key Laboratory of Animal Nutrition Control, South China Agricultural University, Guangzhou, China
- National Engineering Research Center for Breeding Swine Industry, College of Animal Science, South China Agricultural University, Guangzhou, China
- *Correspondence: Lina Wang, ; Qingyan Jiang,
| | - Lina Wang
- Guangdong Provincial Key Laboratory of Animal Nutrition Control, South China Agricultural University, Guangzhou, China
- National Engineering Research Center for Breeding Swine Industry, College of Animal Science, South China Agricultural University, Guangzhou, China
- *Correspondence: Lina Wang, ; Qingyan Jiang,
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31
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Bannerman CA, Douchant K, Sheth PM, Ghasemlou N. The gut-brain axis and beyond: Microbiome control of spinal cord injury pain in humans and rodents. NEUROBIOLOGY OF PAIN (CAMBRIDGE, MASS.) 2021; 9:100059. [PMID: 33426367 PMCID: PMC7779861 DOI: 10.1016/j.ynpai.2020.100059] [Citation(s) in RCA: 14] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 09/17/2020] [Revised: 11/26/2020] [Accepted: 12/10/2020] [Indexed: 12/17/2022]
Abstract
Spinal cord injury (SCI) is a devastating injury to the central nervous system in which 60 to 80% of patients experience chronic pain. Unfortunately, this pain is notoriously difficult to treat, with few effective options currently available. Patients are also commonly faced with various compounding injuries and medical challenges, often requiring frequent hospitalization and antibiotic treatment. Change in the gut microbiome from the "normal" state to one of imbalance, referred to as gut dysbiosis, has been found in both patients and rodent models following SCI. Similarities exist in the bacterial changes observed after SCI and other diseases with chronic pain as an outcome. These changes cause a shift in the regulation of inflammation, causing immune cell activation and secretion of inflammatory mediators that likely contribute to the generation/maintenance of SCI pain. Therefore, correcting gut dysbiosis may be used as a tool towards providing patients with effective pain management and improved quality of life.
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Affiliation(s)
- Courtney A. Bannerman
- Department of Biomedical and Molecular Sciences, Queen’s University, Kingston, Ontario, Canada
| | - Katya Douchant
- Department of Biomedical and Molecular Sciences, Queen’s University, Kingston, Ontario, Canada
- Gastrointestinal Disease Research Unit, Kingston Health Sciences Center, Kingston, Ontario, Canada
| | - Prameet M. Sheth
- Department of Biomedical and Molecular Sciences, Queen’s University, Kingston, Ontario, Canada
- Department of Pathology and Molecular Medicine, Queen’s University, Kingston, Ontario, Canada
- Division of Microbiology, Kingston Health Sciences Centre, Kingston, Ontario, Canada
- Gastrointestinal Disease Research Unit, Kingston Health Sciences Center, Kingston, Ontario, Canada
| | - Nader Ghasemlou
- Department of Biomedical and Molecular Sciences, Queen’s University, Kingston, Ontario, Canada
- Department of Anesthesiology and Perioperative Medicine, Kingston Health Sciences Centre, Kingston, Ontario, Canada
- Centre for Neuroscience Studies, Queen’s University, Kingston, Ontario, Canada
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32
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Shibata M, Tang C. Implications of Transient Receptor Potential Cation Channels in Migraine Pathophysiology. Neurosci Bull 2021; 37:103-116. [PMID: 32870468 PMCID: PMC7811976 DOI: 10.1007/s12264-020-00569-5] [Citation(s) in RCA: 23] [Impact Index Per Article: 7.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/04/2020] [Accepted: 05/11/2020] [Indexed: 12/19/2022] Open
Abstract
Migraine is a common and debilitating headache disorder. Although its pathogenesis remains elusive, abnormal trigeminal and central nervous system activity is likely to play an important role. Transient receptor potential (TRP) channels, which transduce noxious stimuli into pain signals, are expressed in trigeminal ganglion neurons and brain regions closely associated with the pathophysiology of migraine. In the trigeminal ganglion, TRP channels co-localize with calcitonin gene-related peptide, a neuropeptide crucially implicated in migraine pathophysiology. Many preclinical and clinical data support the roles of TRP channels in migraine. In particular, activation of TRP cation channel V1 has been shown to regulate calcitonin gene-related peptide release from trigeminal nerves. Intriguingly, several effective anti-migraine therapies, including botulinum neurotoxin type A, affect the functions of TRP cation channels. Here, we discuss currently available data regarding the roles of major TRP cation channels in the pathophysiology of migraine and the therapeutic applicability thereof.
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Affiliation(s)
- Mamoru Shibata
- Department of Neurology, Keio University School of Medicine, Tokyo, 160-8582, Japan.
- Department of Neurology, Tokyo Dental College Ichikawa General Hospital, Chiba, 272-8513, Japan.
| | - Chunhua Tang
- Department of Neurology, Keio University School of Medicine, Tokyo, 160-8582, Japan
- Department of Neurology and Center for Clinical Neuroscience, Daping Hospital, Third Military Medical University, Chongqing, 400042, China
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33
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Lagomarsino VN, Kostic AD, Chiu IM. Mechanisms of microbial-neuronal interactions in pain and nociception. NEUROBIOLOGY OF PAIN 2020; 9:100056. [PMID: 33392418 PMCID: PMC7772816 DOI: 10.1016/j.ynpai.2020.100056] [Citation(s) in RCA: 33] [Impact Index Per Article: 8.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 03/30/2020] [Revised: 11/18/2020] [Accepted: 11/27/2020] [Indexed: 02/06/2023]
Abstract
Molecular mechanisms of how microorganisms communicate with sensory afferent neurons. How pathogenic microorganisms directly communicate with nociceptor neurons to inflict pain on the host. Symbiotic bacterial communication with gut-extrinsic sensory afferent neurons. Plausible roles on how gut symbionts directly mediate pain and nociception.
Nociceptor sensory neurons innervate barrier tissues that are constantly exposed to microbial stimuli. During infection, pathogenic microorganisms can breach barrier surfaces and produce pain by directly activating nociceptors. Microorganisms that live in symbiotic relationships with their hosts, commensals and mutualists, have also been associated with pain, but the molecular mechanisms of how symbionts act on nociceptor neurons to modulate pain remain largely unknown. In this review, we will discuss the known molecular mechanisms of how microbes directly interact with sensory afferent neurons affecting nociception in the gut, skin and lungs. We will touch on how bacterial, viral and fungal pathogens signal to the host to inflict or suppress pain. We will also discuss recent studies examining how gut symbionts affect pain. Specifically, we will discuss how gut symbionts may interact with sensory afferent neurons either directly, through secretion of metabolites or neurotransmitters, or indirectly,through first signaling to epithelial cells or immune cells, to regulate visceral, neuropathic and inflammatory pain. While this area of research is still in its infancy, more mechanistic studies to examine microbial-sensory neuron crosstalk in nociception may allow us to develop new therapies for the treatment of acute and chronic pain.
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Affiliation(s)
- Valentina N Lagomarsino
- Department of Immunology, Harvard Medical School, Boston, MA 02115, USA.,Joslin Diabetes Center, Boston, MA 02115, USA.,Department of Microbiology, Harvard Medical School, Boston, MA 02115, USA
| | - Aleksandar D Kostic
- Joslin Diabetes Center, Boston, MA 02115, USA.,Department of Microbiology, Harvard Medical School, Boston, MA 02115, USA
| | - Isaac M Chiu
- Department of Immunology, Harvard Medical School, Boston, MA 02115, USA
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34
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Oehler B, Kloka J, Mohammadi M, Ben-Kraiem A, Rittner HL. D-4F, an ApoA-I mimetic peptide ameliorating TRPA1-mediated nocifensive behaviour in a model of neurogenic inflammation. Mol Pain 2020; 16:1744806920903848. [PMID: 31996074 PMCID: PMC6993174 DOI: 10.1177/1744806920903848] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/27/2022] Open
Abstract
Background High doses of capsaicin are recommended for the treatment of neuropathic pain. However, low doses evoke mechanical hypersensitivity. Activation of the capsaicin chemosensor transient receptor potential vanilloid 1 (TRPV1) induces neurogenic inflammation. In addition to the release of pro-inflammatory mediators, reactive oxygen species are produced. These highly reactive molecules generate oxidised phospholipids and 4-hydroxynonenal (4-HNE) which then directly activate TRP ankyrin 1 (TRPA1). The apolipoprotein A-I mimetic peptide D-4F neutralises oxidised phospholipids. Here, we asked whether D-4F ameliorates neurogenic hypersensitivity in rodents by targeting reactive oxygen species and 4-HNE in the capsaicin-evoked pain model. Results Co-application of D-4F ameliorated capsaicin-induced mechanical hypersensitivity and allodynia as well as persistent heat hypersensitivity measured by Randell–Selitto, von Frey and Hargreaves test, respectively. In addition, mechanical hypersensitivity was blocked after co-injection of D-4F with the reactive oxygen species analogue H2O2 or 4-HNE. In vitro studies on dorsal root ganglion neurons and stably transfected cell lines revealed a TRPA1-dependent inhibition of the calcium influx when agonists were pre-incubated with D-4F. The capsaicin-induced calcium influx in TRPV1-expressing cell lines and dorsal root ganglion neurons sustained in the presence of D-4F. Conclusions D-4F is a promising compound to ameliorate TRPA1-dependent hypersensitivity during neurogenic inflammation.
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Affiliation(s)
- Beatrice Oehler
- Department of Anaesthesiology, University Hospital of Würzburg, Würzburg, Germany.,Wolfson Centre for Age-Related Diseases, Institute of Psychiatry, Psychology & Neuroscience, King's College London, London, UK
| | - Jan Kloka
- Department of Anaesthesiology, University Hospital of Würzburg, Würzburg, Germany.,Department of Anaesthesiology, University Hospital of Frankfurt, Frankfurt, Germany
| | - Milad Mohammadi
- Department of Anaesthesiology, University Hospital of Würzburg, Würzburg, Germany.,Department of Anaesthesiology, University Hospital of Cologne, Cologne, Germany
| | - Adel Ben-Kraiem
- Department of Anaesthesiology, University Hospital of Würzburg, Würzburg, Germany
| | - Heike L Rittner
- Department of Anaesthesiology, University Hospital of Würzburg, Würzburg, Germany
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35
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Araya EI, Barroso AR, Turnes JDM, Radulski DR, Jaganaught JRA, Zampronio AR, Chichorro JG. Toll-like receptor 4 (TLR4) signaling in the trigeminal ganglion mediates facial mechanical and thermal hyperalgesia in rats. Physiol Behav 2020; 226:113127. [DOI: 10.1016/j.physbeh.2020.113127] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/08/2020] [Revised: 08/04/2020] [Accepted: 08/05/2020] [Indexed: 02/07/2023]
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36
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Zhan C, Huang M, Yang X, Hou J. Dental nerves: a neglected mediator of pulpitis. Int Endod J 2020; 54:85-99. [PMID: 32880979 DOI: 10.1111/iej.13400] [Citation(s) in RCA: 19] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/14/2020] [Accepted: 08/26/2020] [Indexed: 12/18/2022]
Abstract
As one of the most densely innervated tissues, the dental pulp contains abundant nerve fibres, including sensory, sympathetic and parasympathetic nerve fibres. Studies in animal models and human patients with pulpitis have revealed distinct alterations in protein expression and histological appearance in all types of dental nerve fibres. Various molecules secreted by neurons, such as classical neurotransmitters, neuropeptides and amino acids, not only contribute to the induction, sensitization and maintenance of tooth pain, but also regulate non-neuronal cells, including fibroblasts, odontoblasts, immune cells and vascular endothelial cells. Dental nerves are particularly important for the microcirculatory and immune responses in pulpitis via their release of a variety of functional substances. Further, nerve fibres are found to be involved in dental soft and hard tissue repair. Thus, understanding how dental nerves participate in pulpitis could have important clinical ramifications for endodontic treatment. In this review, the roles of dental nerves in regulating pulpal inflammatory processes are highlighted and their implications for future research on this topic are discussed.
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Affiliation(s)
- C Zhan
- Department of Stomatology, Nanfang Hospital, Southern Medical University, Guangzhou, China
| | - M Huang
- Department of Stomatology, Nanfang Hospital, Southern Medical University, Guangzhou, China
| | - X Yang
- Department of Stomatology, Nanfang Hospital, Southern Medical University, Guangzhou, China
| | - J Hou
- Department of Stomatology, Nanfang Hospital, Southern Medical University, Guangzhou, China
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37
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Blom AB, van den Bosch MH, Blaney Davidson EN, Roth J, Vogl T, van de Loo FA, Koenders M, van der Kraan PM, Geven EJ, van Lent PL. The alarmins S100A8 and S100A9 mediate acute pain in experimental synovitis. Arthritis Res Ther 2020; 22:199. [PMID: 32854769 PMCID: PMC7457270 DOI: 10.1186/s13075-020-02295-9] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/23/2020] [Accepted: 08/17/2020] [Indexed: 01/15/2023] Open
Abstract
Background Synovitis-associated pain is mediated by inflammatory factors that may include S100A8/9, which is able to stimulate nociceptive neurons via Toll-like receptor 4. In this study, we investigated the role of S100A9 in pain response during acute synovitis. Methods Acute synovitis was induced by streptococcal cell wall (SCW) injection in the knee joint of C57Bl/6 (WT) and S100A9−/− mice. The expression of S100A8/A9 was determined in serum and synovium by ELISA and immunohistochemistry. Inflammation was investigated by 99mTc accumulation, synovial cytokine release, and histology at days 1, 2, and 7. To assess pain, weight distribution, gait analysis, and mechanical allodynia were monitored. Activation markers in afferent neurons were determined by qPCR and immunohistochemistry in the dorsal root ganglia (DRG). Differences between groups were tested using a one-way or two-way analysis of variance (ANOVA). Differences in histology were tested with a non-parametric Mann–Whitney U test. p values lower than 0.05 were considered significant. Results Intra-articular SCW injection resulted in increased synovial expression and serum levels of S100A8/A9 at day 1. These increased levels, however, did not contribute to the development of inflammation, since this was equal in S100A9−/− mice. WT mice showed a significantly decreased percentage of weight bearing on the SCW hind paw on day 1, while S100A9−/− mice showed no reduction. Gait analysis showed increased “limping” behavior in WT, but not S100A9−/− mice. Mechanical allodynia was observed but not different between WT and S100A9−/− when measuring paw withdrawal threshold. The gene expression of neuron activation markers NAV1.7, ATF3, and GAP43 in DRG was significantly increased in arthritic WT mice at day 1 but not in S100A9−/− mice. Conclusions S100A8/9, released from the synovium upon inflammation, is an important mediator of pain response in the knee during the acute phase of inflammation.
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Affiliation(s)
- Arjen B Blom
- Experimental Rheumatology, Radboud university medical center, Geert Grooteplein 28, 6525 GA, Nijmegen, The Netherlands.
| | - Martijn H van den Bosch
- Experimental Rheumatology, Radboud university medical center, Geert Grooteplein 28, 6525 GA, Nijmegen, The Netherlands
| | - Esmeralda N Blaney Davidson
- Experimental Rheumatology, Radboud university medical center, Geert Grooteplein 28, 6525 GA, Nijmegen, The Netherlands
| | - Johannes Roth
- Institute of Immunology, University of Münster, Münster, Germany
| | - Thomas Vogl
- Institute of Immunology, University of Münster, Münster, Germany
| | - Fons A van de Loo
- Experimental Rheumatology, Radboud university medical center, Geert Grooteplein 28, 6525 GA, Nijmegen, The Netherlands
| | - Marije Koenders
- Experimental Rheumatology, Radboud university medical center, Geert Grooteplein 28, 6525 GA, Nijmegen, The Netherlands
| | - Peter M van der Kraan
- Experimental Rheumatology, Radboud university medical center, Geert Grooteplein 28, 6525 GA, Nijmegen, The Netherlands
| | - Edwin J Geven
- Experimental Rheumatology, Radboud university medical center, Geert Grooteplein 28, 6525 GA, Nijmegen, The Netherlands
| | - Peter L van Lent
- Experimental Rheumatology, Radboud university medical center, Geert Grooteplein 28, 6525 GA, Nijmegen, The Netherlands
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38
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Donnelly CR, Chen O, Ji RR. How Do Sensory Neurons Sense Danger Signals? Trends Neurosci 2020; 43:822-838. [PMID: 32839001 DOI: 10.1016/j.tins.2020.07.008] [Citation(s) in RCA: 86] [Impact Index Per Article: 21.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/30/2020] [Revised: 07/11/2020] [Accepted: 07/27/2020] [Indexed: 12/27/2022]
Abstract
Sensory neurons are activated by physical and chemical stimuli, eliciting sensations such as temperature, touch, pain, and itch. From an evolutionary perspective, sensing danger is essential for organismal survival. Upon infection and injury, immune cells respond to pathogen/damage-associated molecular patterns (PAMPs/DAMPs) through pattern recognition receptors (PRRs) such as Toll-like receptors (TLRs), and produce inflammatory mediators that activate sensory neurons through neuro-immune interactions. Sensory neurons also express TLRs and other PRRs that directly sense danger signals after injury or during infection, leading to pain, itch, or analgesia. In addition to slow-acting canonical TLR signaling, TLRs function uniquely in sensory neurons through non-canonical coupling to ion channels, enabling rapid modulation of neuronal activity. We discuss how sensory neurons utilize TLRs and other PRR pathways to detect danger signals in their environment.
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Affiliation(s)
- Christopher R Donnelly
- Center for Translational Pain Medicine, Department of Anesthesiology, Duke University Medical Center, Durham, NC 27710, USA
| | - Ouyang Chen
- Center for Translational Pain Medicine, Department of Anesthesiology, Duke University Medical Center, Durham, NC 27710, USA; Department of Cell Biology, Duke University Medical Center, Durham, NC 27710, USA
| | - Ru-Rong Ji
- Center for Translational Pain Medicine, Department of Anesthesiology, Duke University Medical Center, Durham, NC 27710, USA; Department of Cell Biology, Duke University Medical Center, Durham, NC 27710, USA; Department of Neurobiology, Duke University Medical Center, Durham, NC 27710, USA.
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39
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Oo TT, Pratchayasakul W, Chattipakorn N, Chattipakorn SC. Potential Roles of Myeloid Differentiation Factor 2 on Neuroinflammation and Its Possible Interventions. Mol Neurobiol 2020; 57:4825-4844. [PMID: 32803490 DOI: 10.1007/s12035-020-02066-2] [Citation(s) in RCA: 9] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/18/2020] [Accepted: 08/07/2020] [Indexed: 02/06/2023]
Abstract
Neuroinflammation is the primary response by immune cells in the nervous system to protect against infection. Chronic and uncontrolled neuroinflammation triggers neuronal injury and neuronal death resulting in a variety of neurodegenerative disorders. Therefore, fine tuning of the immune response in the nervous system is now extensively considered as a potential therapeutic intervention for those diseases. The immune cells of the nervous system express Toll-like receptor 4 (TLR4) together with myeloid differentiation factor 2 (MD-2) to protect against the pathogens. Over the last 10 years, antagonists targeting the functional domains of MD-2 have become attractive pharmacological intervention strategies in pre-clinical studies into neuroinflammation and its associated brain pathologies. This review aims to summarize and discuss the roles of TLR4-MD-2 signaling pathway activation in various models of neuroinflammation. This review article also highlights the studies reporting the effect of MD-2 antagonists on neuroinflammation in in vitro and in vivo studies.
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Affiliation(s)
- Thura Tun Oo
- Neurophysiology Unit, Cardiac Electrophysiology Research and Training Center, Faculty of Medicine, Chiang Mai University, Chiang Mai, 50200, Thailand.,Cardiac Electrophysiology Unit, Department of Physiology, Faculty of Medicine, Chiang Mai University, Chiang Mai, Thailand.,Center of Excellence in Cardiac Electrophysiology, Chiang Mai University, Chiang Mai, Thailand
| | - Wasana Pratchayasakul
- Neurophysiology Unit, Cardiac Electrophysiology Research and Training Center, Faculty of Medicine, Chiang Mai University, Chiang Mai, 50200, Thailand.,Cardiac Electrophysiology Unit, Department of Physiology, Faculty of Medicine, Chiang Mai University, Chiang Mai, Thailand.,Center of Excellence in Cardiac Electrophysiology, Chiang Mai University, Chiang Mai, Thailand
| | - Nipon Chattipakorn
- Neurophysiology Unit, Cardiac Electrophysiology Research and Training Center, Faculty of Medicine, Chiang Mai University, Chiang Mai, 50200, Thailand.,Cardiac Electrophysiology Unit, Department of Physiology, Faculty of Medicine, Chiang Mai University, Chiang Mai, Thailand.,Center of Excellence in Cardiac Electrophysiology, Chiang Mai University, Chiang Mai, Thailand
| | - Siriporn C Chattipakorn
- Neurophysiology Unit, Cardiac Electrophysiology Research and Training Center, Faculty of Medicine, Chiang Mai University, Chiang Mai, 50200, Thailand. .,Center of Excellence in Cardiac Electrophysiology, Chiang Mai University, Chiang Mai, Thailand. .,Department of Oral Biology and Diagnostic Sciences, Faculty of Dentistry, Faculty of Medicine, Chiang Mai University, Chiang Mai, 50200, Thailand.
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40
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Filippini HF, Molska GR, Zanjir M, Arudchelvan Y, Gong SG, Campos MM, Avivi-Arber L, Sessle BJ. Toll-Like Receptor 4 in the Rat Caudal Medulla Mediates Tooth Pulp Inflammatory Pain. Front Neurosci 2020; 14:643. [PMID: 32655361 PMCID: PMC7324534 DOI: 10.3389/fnins.2020.00643] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/26/2019] [Accepted: 05/25/2020] [Indexed: 12/20/2022] Open
Abstract
The aims of this study were to investigate if Toll-like receptor 4 (TLR4) is expressed in the medullary dorsal horn (MDH) and if medullary application of a TLR4 antagonist (lipopolysaccharides from Rhodobacter sphaeroides, LPS-RS) can attenuate changes in nociceptive sensorimotor responses or TLR4 expression that might be evoked by mustard oil (MO) application to the right maxillary first molar tooth pulp. Of 41 adult male Sprague-Dawley rats used in the study, 23 received intrathecal application of the TLR4 antagonist LPS-RS (25 μg/10 μl; LPS-RS group) or isotonic saline (10 μl; vehicle control group) 10 min before pulpal application of MO (95%; 0.2 μl). Bilateral electromyographic (EMG) activities of the anterior digastric and masseter muscles were recorded continuously before and until 15 min after the MO application to the pulp. In 6 of these 23 rats and an additional 18 rats, the caudal medulla containing the ipsilateral and contralateral MDH was removed after euthanasia for subsequent Western Blot analysis of TLR4 expression in LPS-RS (n = 8) and vehicle (n = 8) groups and a naïve group (n = 8). The % change from baseline in the MO-evoked EMG activities within the anterior digastric muscles were significantly smaller in the LPS-RS group than the control group (two-way ANOVA, post hoc Bonferroni, P < 0.0001). Western Blot analysis revealed similar levels of TLR4 expression in the caudal medulla of the naïve, vehicle and LPS-RS groups. These novel findings suggest that TLR4 signaling in the caudal medulla may mediate MO-induced acute dental inflammatory pain in rats.
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Affiliation(s)
- Helena F Filippini
- Programa de Pós-graduação em Odontologia, Escola de Ciência da Saúde e da Vida, Pontifícia Universidade Católica do Rio Grande do Sul, Porto Alegre, Brazil.,Faculty of Dentistry, University of Toronto, Toronto, ON, Canada
| | | | - Maryam Zanjir
- Faculty of Dentistry, University of Toronto, Toronto, ON, Canada
| | | | - Siew-Ging Gong
- Faculty of Dentistry, University of Toronto, Toronto, ON, Canada
| | - Maria M Campos
- Programa de Pós-graduação em Odontologia, Escola de Ciência da Saúde e da Vida, Pontifícia Universidade Católica do Rio Grande do Sul, Porto Alegre, Brazil.,Centro de Pesquisa em Toxicologia e Farmacologia, Escola de Ciências da Saúde e da Vida, Pontifícia Universidade Católica do Rio Grande do Sul, Porto Alegre, Brazil
| | - Limor Avivi-Arber
- Faculty of Dentistry, University of Toronto, Toronto, ON, Canada.,Centre for the Study of Pain, University of Toronto, Toronto, ON, Canada
| | - Barry J Sessle
- Faculty of Dentistry, University of Toronto, Toronto, ON, Canada.,Centre for the Study of Pain, University of Toronto, Toronto, ON, Canada.,Departament of Physiology, Faculty of Medicine, University of Toronto, Toronto, ON, Canada
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41
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dos Santos RS, Veras FP, Ferreira DW, Sant'Anna MB, Lollo PCB, Cunha TM, Galdino G. Involvement of the Hsp70/TLR4/IL‐6 and TNF‐α pathways in delayed‐onset muscle soreness. J Neurochem 2020; 155:29-44. [DOI: 10.1111/jnc.15006] [Citation(s) in RCA: 9] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/05/2019] [Revised: 03/09/2020] [Accepted: 03/12/2020] [Indexed: 12/31/2022]
Affiliation(s)
| | | | - David Wilson Ferreira
- Department of Neurobiology University of Pittsburgh School of Medicine Pittsburgh PA USA
| | | | | | | | - Giovane Galdino
- Sciences of Motricity Institute Federal University of Alfenas Alfenas Brazil
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42
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Miller RJ, Malfait AM, Miller RE. The innate immune response as a mediator of osteoarthritis pain. Osteoarthritis Cartilage 2020; 28:562-571. [PMID: 31862470 PMCID: PMC6951330 DOI: 10.1016/j.joca.2019.11.006] [Citation(s) in RCA: 55] [Impact Index Per Article: 13.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 05/13/2019] [Accepted: 11/20/2019] [Indexed: 02/08/2023]
Abstract
In this narrative review, we discuss the emerging role of innate immunity in osteoarthritis (OA) joint pain. First, we give a brief description of the pain pathway in the context of OA. Then we consider how neuro-immune signaling pathways may promote OA pain. First, activation of neuronal Pattern Recognition Receptors by mediators released in a damaged joint can result in direct excitation of nociceptors, as well as in production of chemokines and cytokines. Secondly, indirect neuro-immune signaling may occur when innate immune cells produce algogenic factors, including chemokines and cytokines, that act on the pain pathway. Neuro-immune crosstalk occurs at different levels of the pathway, starting in the joint but also in the innervating dorsal root ganglia and in the dorsal horn. Synovitis is characterized by recruitment of immune cells, including macrophages, mast cells, and CD4+ lymphocytes, which may contribute to nociceptor sensitization and OA pain through production of algogenic factors that amplify the activation of sensory neurons. We discuss examples where this scenario has been suggested by findings in human OA and in animal models. Overall, increasing evidence suggests that innate immune pathways play an initiating as well as facilitating role in pain, but information on how these pathways operate in OA remains limited. Since these innate pathways are eminently targetable, future studies in this area may provide fruitful leads towards a better management of symptomatic OA.
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43
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Kaewpitak A, Bauer CS, Seward EP, Boissonade FM, Douglas CWI. Porphyromonas gingivalis
lipopolysaccharide rapidly activates trigeminal sensory neurons and may contribute to pulpal pain. Int Endod J 2020; 53:846-858. [DOI: 10.1111/iej.13282] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/11/2018] [Accepted: 02/12/2020] [Indexed: 01/19/2023]
Affiliation(s)
- A. Kaewpitak
- School of Clinical Dentistry University of Sheffield Sheffield UK
| | - C. S. Bauer
- Department of Biomedical Science University of Sheffield Sheffield UK
| | - E. P. Seward
- Department of Biomedical Science University of Sheffield Sheffield UK
| | - F. M. Boissonade
- School of Clinical Dentistry University of Sheffield Sheffield UK
| | - C. W. I. Douglas
- School of Clinical Dentistry University of Sheffield Sheffield UK
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44
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Wang TT, Xu XY, Lin W, Hu DD, Shi W, Jia X, Wang H, Song NJ, Zhang YQ, Zhang L. Activation of Different Heterodimers of TLR2 Distinctly Mediates Pain and Itch. Neuroscience 2020; 429:245-255. [DOI: 10.1016/j.neuroscience.2020.01.010] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/08/2019] [Revised: 01/03/2020] [Accepted: 01/07/2020] [Indexed: 10/25/2022]
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45
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Evoked and spontaneous pain assessment during tooth pulp injury. Sci Rep 2020; 10:2759. [PMID: 32066827 PMCID: PMC7026088 DOI: 10.1038/s41598-020-59742-5] [Citation(s) in RCA: 21] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/26/2019] [Accepted: 02/03/2020] [Indexed: 12/16/2022] Open
Abstract
Injury of the tooth pulp is excruciatingly painful and yet the receptors and neural circuit mechanisms that transmit this form of pain remain poorly defined in both the clinic and preclinical rodent models. Easily quantifiable behavioral assessment in the mouse orofacial area remains a major bottleneck in uncovering molecular mechanisms that govern inflammatory pain in the tooth. In this study we sought to address this problem using the Mouse Grimace Scale and a novel approach to the application of mechanical Von Frey hair stimuli. We use a dental pulp injury model that exposes the pulp to the outside environment, a procedure we have previously shown produces inflammation. Using RNAscope technology, we demonstrate an upregulation of genes that contribute to the pain state in the trigeminal ganglia of injured mice. We found that mice with dental pulp injury have greater Mouse Grimace Scores than sham within 24 hours of injury, suggestive of spontaneous pain. We developed a scoring system of mouse refusal to determine thresholds for mechanical stimulation of the face with Von Frey filaments. This method revealed that mice with a unilateral dental injury develop bilateral mechanical allodynia that is delayed relative to the onset of spontaneous pain. This work demonstrates that tooth pain can be quantified in freely behaving mice using approaches common for other types of pain assessment. Harnessing these assays in the orofacial area during gene manipulation should assist in uncovering mechanisms for tooth pulp inflammatory pain and other forms of trigeminal pain.
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46
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Garcia MM, Goicoechea C, Molina-Álvarez M, Pascual D. Toll-like receptor 4: A promising crossroads in the diagnosis and treatment of several pathologies. Eur J Pharmacol 2020; 874:172975. [PMID: 32017939 DOI: 10.1016/j.ejphar.2020.172975] [Citation(s) in RCA: 32] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/31/2019] [Revised: 12/20/2019] [Accepted: 01/29/2020] [Indexed: 12/26/2022]
Abstract
Toll-like receptor 4 (TLR4) is expressed in a wide variety of cells and is the central component of the mammalian innate immune system. Since its discovery in 1997, TLR4 has been assigned an ever-increasing number of functions that extend from pathogen recognition to tissue damage identification and promotion of the intrinsic "damage repair response" in pain, intestinal, respiratory and vascular disorders. Precisely, the finding of conserved sequence homology among species along with the molecular and functional characterisation of the TLR4 gene enabled researchers to envisage a common operating system in the activation of innate immunity and the initiation of plastic changes at the onset of chronic pain. Malfunctioning in other conditions was conceived in parallel. In this respect, "pivot" proteins and pathway redundancy are not just evolutionary leftovers but essential for normal functioning or cell survival. Indeed, at present, TLR4 single nucleotide polymorphisms (SNP) and their association with certain dysfunctions and diseases are being confirmed in different pools of patients. However, despite its ability to trigger pathogen infection or alternatively tissue injury communications to immune system, TLR4 targeting might not be considered a panacea. This review article represents a compilation of what we know about TLR4 from clinics and basic research on the 20th anniversary of its discovery. Understanding how to fine-tune the interaction between TLR4 and its specific ligands may lead in the next decades to the development of promising new treatments, reducing polypharmacy and probably having an impact on drug use in numerous pathologies.
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Affiliation(s)
- Miguel M Garcia
- Area of Pharmacology, Nutrition and Bromatology, Department of Basic Health Sciences, Universidad Rey Juan Carlos, Avda, Atenas S/n, 28922, Alcorcón, Spain
| | - Carlos Goicoechea
- Area of Pharmacology, Nutrition and Bromatology, Department of Basic Health Sciences, Universidad Rey Juan Carlos, Avda, Atenas S/n, 28922, Alcorcón, Spain
| | - Miguel Molina-Álvarez
- Area of Pharmacology, Nutrition and Bromatology, Department of Basic Health Sciences, Universidad Rey Juan Carlos, Avda, Atenas S/n, 28922, Alcorcón, Spain
| | - David Pascual
- Area of Pharmacology, Nutrition and Bromatology, Department of Basic Health Sciences, Universidad Rey Juan Carlos, Avda, Atenas S/n, 28922, Alcorcón, Spain.
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Pluta L, Yousefi B, Damania B, Khan AA. Endosomal TLR-8 Senses microRNA-1294 Resulting in the Production of NFḱB Dependent Cytokines. Front Immunol 2019; 10:2860. [PMID: 31867014 PMCID: PMC6909240 DOI: 10.3389/fimmu.2019.02860] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/03/2019] [Accepted: 11/21/2019] [Indexed: 12/21/2022] Open
Abstract
The primary function of toll-like receptor 8 (TLR-8) is the detection of viruses and other microbial pathogens. Recent evidence suggests that TLR-8 also senses host microRNAs (miRNAs) and implicate TLR-8 in autoimmune disorders. This study examined the interaction between miR-1294 and TLR-8. We first performed a BLAST search to identify miRNAs with the same sequences as two core motifs of miR-1294. Next, we examined NFḱB activation induced by the binding of miR-1294 mimic to endosomal TLR-8. HEK-Blue™ hTLR-8 cells (Invivogen), a HEK293 cell line co-transfected with human TLR-8 gene, were incubated with miR-1294 mimic. A TLR-8 agonist ssRNA40, was used as a positive control. Using the same experimental set up, we also examined the effects of miR-1294 and its two core motifs (Integrated DNA Technologies) on IL-8, IL-1β, and TNFα. Data were analyzed using t-test or one-way ANOVA and Dunnets post-hoc test. Using miRCarta we identified 29 other mature human miRNAs or their precursors which contain the same core motifs as miR-1294. Our data show that miR-1294 activates NFḱB in cells expressing TLR-8 (p < 0.05). miR-1294, and its core motifs induce expression of IL-8, IL-1β, and TNFα via TLR8 activation (p < 0.05). This constitutes a novel mechanism by which endosomal TLR-8 senses host miRNAs resulting in the release of pro-inflammatory cytokines and thus potentially contributing to autoimmune disorders.
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Affiliation(s)
- Linda Pluta
- Department of Microbiology and Immunology, School of Medicine, University of North Carolina at Chapel Hill, Chapel Hill, NC, United States
| | - Babak Yousefi
- Department of Oral and Craniofacial Health Sciences, School of Dentistry, University of North Carolina at Chapel Hill, Chapel Hill, NC, United States
| | - Blossom Damania
- Department of Microbiology and Immunology, School of Medicine, University of North Carolina at Chapel Hill, Chapel Hill, NC, United States
| | - Asma A Khan
- Department of Endodontics, Dental School, University of Texas Health Science Center at San Antonio, San Antonio, TX, United States
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DeMarco GJ, Nunamaker EA. A Review of the Effects of Pain and Analgesia on Immune System Function and Inflammation: Relevance for Preclinical Studies. Comp Med 2019; 69:520-534. [PMID: 31896389 PMCID: PMC6935697 DOI: 10.30802/aalas-cm-19-000041] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/17/2022]
Abstract
One of the most significant challenges facing investigators, laboratory animal veterinarians, and IACUCs, is how to balance appropriate analgesic use, animal welfare, and analgesic impact on experimental results. This is particularly true for in vivo studies on immune system function and inflammatory disease. Often times the effects of analgesic drugs on a particular immune function or model are incomplete or don't exist. Further complicating the picture is evidence of the very tight integration and bidirectional functionality between the immune system and branches of the nervous system involved in nociception and pain. These relationships have advanced the concept of understanding pain as a protective neuroimmune function and recognizing pathologic pain as a neuroimmune disease. This review strives to summarize extant literature on the effects of pain and analgesia on immune system function and inflammation in the context of preclinical in vivo studies. The authors hope this work will help to guide selection of analgesics for preclinical studies of inflammatory disease and immune system function.
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Key Words
- cb,endocannabinoid receptor
- cd,crohn disease
- cfa, complete freund adjuvant
- cgrp,calcitonin gene-related peptide
- cox,cyclooxygenase
- ctl, cytotoxic t-lymphocytes
- damp,damage-associated molecular pattern molecules
- drg,dorsal root ganglion
- dss, dextran sodium sulphate
- ecs,endocannabinoid system
- ibd, inflammatory bowel disease
- ifa,incomplete freund adjuvant
- las, local anesthetics
- pamp,pathogen-associated molecular pattern molecules
- pge2, prostaglandin e2
- p2y, atp purine receptor y
- p2x, atp purine receptor x
- tnbs, 2,4,6-trinitrobenzene sulphonic acid
- trp, transient receptor potential ion channels
- trpv, transient receptor potential vanilloid
- tg,trigeminal ganglion
- uc,ulcerative colitis
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Affiliation(s)
- George J DeMarco
- Department of Animal Medicine, University of Massachusetts Medical School, Worcester, Massachusetts;,
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Lin C, Zhao S, Zhu Y, Fan Z, Wang J, Zhang B, Chen Y. Microbiota-gut-brain axis and toll-like receptors in Alzheimer's disease. Comput Struct Biotechnol J 2019; 17:1309-1317. [PMID: 31921396 PMCID: PMC6944716 DOI: 10.1016/j.csbj.2019.09.008] [Citation(s) in RCA: 57] [Impact Index Per Article: 11.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/31/2019] [Revised: 09/19/2019] [Accepted: 09/22/2019] [Indexed: 12/21/2022] Open
Abstract
Alzheimer’s disease (AD) is a multifactorial disease which involves both the periphery and central nervous system (CNS). It has been recently recognized that gut microbiota interacts with the gut and brain (microbiota-gut-brain axis), contributing to the pathogenesis of neurodegenerative diseases, such as AD. Dysbiosis of gut microbiota can induce increased intestinal permeability and systemic inflammation, which may lead to the development of AD pathologies and cognitive impairment via the neural, immune, endocrine, and metabolic pathways. Toll-like receptors (TLRs) play an important role in the innate immune system via recognizing microbes-derived pathogens and initiating the inflammatory process. TLRs have also been found in the brain, especially in the microglia, and have been indicated in the development of AD. In this review, we summarized the relationship between microbiota-gut-brain axis and AD, as well as the complex role of TLRs in AD. Intervention of the gut microbiota or modulation of TLRs properly might emerge as promising preventive and therapeutic strategies for AD.
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Affiliation(s)
- Caixiu Lin
- Department of Neurology, The Second Affiliated Hospital, Zhejiang University School of Medicine, Hangzhou, China.,Department of Neurology, Affiliated Hangzhou First People's Hospital, Zhejiang University School of Medicine, Hangzhou, China
| | - Shuai Zhao
- Department of Neurology, The Second Affiliated Hospital, Zhejiang University School of Medicine, Hangzhou, China
| | - Yueli Zhu
- Department of Neurology, The Second Affiliated Hospital, Zhejiang University School of Medicine, Hangzhou, China
| | - Ziqi Fan
- Department of Neurology, The Second Affiliated Hospital, Zhejiang University School of Medicine, Hangzhou, China
| | - Jing Wang
- Department of Geriatric, The Second Affiliated Hospital, Zhejiang University School of Medicine, Hangzhou, China
| | - Baorong Zhang
- Department of Neurology, The Second Affiliated Hospital, Zhejiang University School of Medicine, Hangzhou, China
| | - Yanxing Chen
- Department of Neurology, The Second Affiliated Hospital, Zhejiang University School of Medicine, Hangzhou, China
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Miller RE, Scanzello CR, Malfait AM. An emerging role for Toll-like receptors at the neuroimmune interface in osteoarthritis. Semin Immunopathol 2019; 41:583-594. [PMID: 31612243 DOI: 10.1007/s00281-019-00762-3] [Citation(s) in RCA: 35] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/08/2019] [Accepted: 09/09/2019] [Indexed: 12/31/2022]
Abstract
Osteoarthritis (OA) is a chronic progressive, painful disease of synovial joints, characterized by cartilage degradation, subchondral bone remodeling, osteophyte formation, and synovitis. It is now widely appreciated that the innate immune system, and in particular Toll-like receptors (TLRs), contributes to pathological changes in OA joint tissues. Furthermore, it is now also increasingly recognized that TLR signaling plays a key role in initiating and maintaining pain. Here, we reviewed the literature of the past 5 years with a focus on how TLRs may contribute to joint damage and pain in OA. We discuss biological effects of specific damage-associated molecular patterns (DAMPs) which act as TLR ligands in vitro, including direct effects on pain-sensing neurons. We then discuss the phenotype of transgenic mice that target TLR pathways, and provide evidence for a complex balance between pro- and anti-inflammatory signaling pathways activated by OA DAMPs. Finally, we summarize clinical evidence implicating TLRs in OA pathogenesis, including polymorphisms and surrogate markers of disease activity. Our review of the literature led us to propose a model where multi-directional crosstalk between connective tissue cells (chondrocytes, fibroblasts), innate immune cells, and sensory neurons in the affected joint may promote OA pathology and pain.
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Affiliation(s)
- Rachel E Miller
- Division of Rheumatology, Department of Internal Medicine, Rush University Medical Center, 1611 W Harrison Street, Chicago, IL, 60612, USA
| | - Carla R Scanzello
- Section of Rheumatology and Translational Musculoskeletal Research Center, Corporal Michael J. Crescenz Veterans Affairs Medical Center & Division of Rheumatology, University of Pennsylvania Perelman School of Medicine, Philadelphia, PA, 19104, USA
| | - Anne-Marie Malfait
- Division of Rheumatology, Department of Internal Medicine, Rush University Medical Center, 1611 W Harrison Street, Chicago, IL, 60612, USA.
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