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Bietar B, Tanner S, Lehmann C. Neuroprotection and Beyond: The Central Role of CB1 and CB2 Receptors in Stroke Recovery. Int J Mol Sci 2023; 24:16728. [PMID: 38069049 PMCID: PMC10705908 DOI: 10.3390/ijms242316728] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/19/2023] [Revised: 11/20/2023] [Accepted: 11/21/2023] [Indexed: 12/18/2023] Open
Abstract
The endocannabinoid system, with its intricate presence in numerous cells, tissues, and organs, offers a compelling avenue for therapeutic interventions. Central to this system are the cannabinoid receptors 1 and 2 (CB1R and CB2R), whose ubiquity can introduce complexities in targeted treatments due to their wide-ranging physiological influence. Injuries to the central nervous system (CNS), including strokes and traumatic brain injuries, induce localized pro-inflammatory immune responses, termed neuroinflammation. Research has shown that compensatory immunodepression usually follows, and these mechanisms might influence immunity, potentially affecting infection risks in patients. As traditional preventive treatments like antibiotics face challenges, the exploration of immunomodulatory therapies offers a promising alternative. This review delves into the potential neuroprotective roles of the cannabinoid receptors: CB1R's involvement in mitigating excitotoxicity and CB2R's dual role in promoting cell survival and anti-inflammatory responses. However, the potential of cannabinoids to reduce neuroinflammation must be weighed against the risk of exacerbating immunodepression. Though the endocannabinoid system promises numerous therapeutic benefits, understanding its multifaceted signaling mechanisms and outcomes remains a challenge.
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Affiliation(s)
- Bashir Bietar
- Department of Pharmacology, Dalhousie University, Halifax, NS B3H 4R2, Canada; (B.B.); (S.T.)
- Department of Anesthesia, Pain Management, and Perioperative Medicine, Dalhousie University, Halifax, NS B3H 4R2, Canada
| | - Sophie Tanner
- Department of Pharmacology, Dalhousie University, Halifax, NS B3H 4R2, Canada; (B.B.); (S.T.)
- Department of Anesthesia, Pain Management, and Perioperative Medicine, Dalhousie University, Halifax, NS B3H 4R2, Canada
| | - Christian Lehmann
- Department of Pharmacology, Dalhousie University, Halifax, NS B3H 4R2, Canada; (B.B.); (S.T.)
- Department of Anesthesia, Pain Management, and Perioperative Medicine, Dalhousie University, Halifax, NS B3H 4R2, Canada
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Wu F, Liu Z, Zhou L, Ye D, Zhu Y, Huang K, Weng Y, Xiong X, Zhan R, Shen J. Systemic immune responses after ischemic stroke: From the center to the periphery. Front Immunol 2022; 13:911661. [PMID: 36211352 PMCID: PMC9533176 DOI: 10.3389/fimmu.2022.911661] [Citation(s) in RCA: 13] [Impact Index Per Article: 6.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/03/2022] [Accepted: 07/18/2022] [Indexed: 12/01/2022] Open
Abstract
Ischemic stroke is a leading cause of disability and death. It imposes a heavy economic burden on individuals, families and society. The mortality rate of ischemic stroke has decreased with the help of thrombolytic drug therapy and intravascular intervention. However, the nerve damage caused by ischemia-reperfusion is long-lasting and followed by multiple organ dysfunction. In this process, the immune responses manifested by systemic inflammatory responses play an important role. It begins with neuroinflammation following ischemic stroke. The large number of inflammatory cells released after activation of immune cells in the lesion area, along with the deactivated neuroendocrine and autonomic nervous systems, link the center with the periphery. With the activation of systemic immunity and the emergence of immunosuppression, peripheral organs become the second “battlefield” of the immune response after ischemic stroke and gradually become dysfunctional and lead to an adverse prognosis. The purpose of this review was to describe the systemic immune responses after ischemic stroke. We hope to provide new ideas for future research and clinical treatments to improve patient outcomes and quality of life.
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Affiliation(s)
- Fan Wu
- Department of Neurosurgery, First Affiliated Hospital, College of Medicine, Zhejiang University, Hangzhou, China
| | - Zongchi Liu
- Department of Neurosurgery, First Affiliated Hospital, College of Medicine, Zhejiang University, Hangzhou, China
| | - Lihui Zhou
- Department of Neurosurgery, First Affiliated Hospital, College of Medicine, Zhejiang University, Hangzhou, China
| | - Di Ye
- Department of Neurosurgery, First Affiliated Hospital, College of Medicine, Zhejiang University, Hangzhou, China
| | - Yu Zhu
- Department of Neurosurgery, First Affiliated Hospital, College of Medicine, Zhejiang University, Hangzhou, China
| | - Kaiyuan Huang
- Department of Neurosurgery, First Affiliated Hospital, College of Medicine, Zhejiang University, Hangzhou, China
| | - Yuxiang Weng
- Department of Neurosurgery, First Affiliated Hospital, College of Medicine, Zhejiang University, Hangzhou, China
| | - Xiaoxing Xiong
- Department of Clinical Laboratory, Renmin Hospital, Faculty of Medical Sciences, Wuhan University, Wuhan, China
| | - Renya Zhan
- Department of Neurosurgery, First Affiliated Hospital, College of Medicine, Zhejiang University, Hangzhou, China
- *Correspondence: Jian Shen, ; Renya Zhan,
| | - Jian Shen
- Department of Neurosurgery, First Affiliated Hospital, College of Medicine, Zhejiang University, Hangzhou, China
- *Correspondence: Jian Shen, ; Renya Zhan,
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Gao D, Gao X, Yang F, Wang Q. Neuroimmune Crosstalk in Rheumatoid Arthritis. Int J Mol Sci 2022; 23:ijms23158158. [PMID: 35897734 PMCID: PMC9332175 DOI: 10.3390/ijms23158158] [Citation(s) in RCA: 6] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/04/2022] [Revised: 07/20/2022] [Accepted: 07/21/2022] [Indexed: 12/29/2022] Open
Abstract
Recent studies have demonstrated that immunological disease progression is closely related to abnormal function of the central nervous system (CNS). Rheumatoid arthritis (RA) is a chronic, inflammatory synovitis-based systemic immune disease of unknown etiology. In addition to joint pathological damage, RA has been linked to neuropsychiatric comorbidities, including depression, schizophrenia, and anxiety, increasing the risk of neurodegenerative diseases in life. Immune cells and their secreted immune factors will stimulate the peripheral and central neuronal systems that regulate innate and adaptive immunity. The understanding of autoimmune diseases has largely advanced insights into the molecular mechanisms of neuroimmune interaction. Here, we review our current understanding of CNS comorbidities and potential physiological mechanisms in patients with RA, with a focus on the complex and diverse regulation of mood and distinct patterns of peripheral immune activation in patients with rheumatoid arthritis. And in our review, we also discussed the role that has been played by peripheral neurons and CNS in terms of neuron mechanisms in RA immune challenges, and the related neuron-immune crosstalk.
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Affiliation(s)
- Dashuang Gao
- The Brain Cognition and Brain Disease Institute, Shenzhen Institute of Advanced Technology, Chinese Academy of Sciences, Shenzhen-Hong Kong Institute of Brain Science-Shenzhen Fundamental Research Institutions, Shenzhen 518055, China;
- University of Chinese Academy of Sciences, Beijing 100049, China
| | - Xu Gao
- Shenzhen Key Laboratory of Inflammatory and Immunology Diseases, Shenzhen 518036, China;
- Department of Rheumatism and Immunology, Peking University Shenzhen Hospital, Shenzhen Peking University-Hong Kong University of Science and Technology Medical Center, Shenzhen 518036, China
| | - Fan Yang
- The Brain Cognition and Brain Disease Institute, Shenzhen Institute of Advanced Technology, Chinese Academy of Sciences, Shenzhen-Hong Kong Institute of Brain Science-Shenzhen Fundamental Research Institutions, Shenzhen 518055, China;
- University of Chinese Academy of Sciences, Beijing 100049, China
- Correspondence: (F.Y.); (Q.W.)
| | - Qingwen Wang
- Shenzhen Key Laboratory of Inflammatory and Immunology Diseases, Shenzhen 518036, China;
- Department of Rheumatism and Immunology, Peking University Shenzhen Hospital, Shenzhen Peking University-Hong Kong University of Science and Technology Medical Center, Shenzhen 518036, China
- Correspondence: (F.Y.); (Q.W.)
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Sun H, Li S, Xu Z, Liu C, Gong P, Deng Q, Yan F. SNHG15 is a negative regulator of inflammation by mediating TRAF2 ubiquitination in stroke-induced immunosuppression. J Neuroinflammation 2022; 19:1. [PMID: 34980176 PMCID: PMC8722265 DOI: 10.1186/s12974-021-02372-z] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/11/2021] [Accepted: 12/22/2021] [Indexed: 12/19/2022] Open
Abstract
BACKGROUND Abnormal expression of long noncoding RNAs (lncRNAs) has been reported in the acute stage of acute ischemic stroke (AIS). This study aimed to explore differential lncRNA expression in the subpopulations of peripheral blood mononuclear cells (PBMCs) from AIS patients and further evaluate its underlying mechanisms in stroke-induced immunosuppression. METHODS We reanalyzed lncRNA microarray data and investigated abnormally expressed lncRNAs in the subpopulations of PBMCs by magnetic cell sorting and real-time quantitative PCR. The potential mechanism of small nucleolar RNA host gene 15 (SNHG15) was explored through in vitro and in vivo approaches. RESULTS The stroke-induced SNHG15 acted as a checkpoint to inhibit peripheral inflammatory responses. Functional studies showed that SNHG15 promoted M2 macrophage polarization. Mechanistically, SNHG15 expression was dysregulated through the Janus kinase (JAK)-signal transducer and activator of transcription 6 (STAT6) signaling pathway. SNHG15, localized in the cytoplasm, interfered with K63-linked ubiquitination of tumor necrosis factor receptor-associated factor 2 and thereby repressed the activation of mitogen-activated protein kinase and nuclear factor kappa-B signaling pathways and prevented the production of proinflammatory cytokines. Administration of an adenovirus targeting SNHG15 improved stroke-induced immunosuppression in mice. CONCLUSIONS This study identified SNHG15 as a negative regulator of inflammation in stroke-induced immunosuppression, suggesting it as a novel biomarker and therapeutic target in stroke-associated infection. Trial registration ClinicalTrials.gov NCT04175691. Registered November 25, 2019, https://www.clinicaltrials.gov/ct2/show/NCT04175691 .
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Affiliation(s)
- Huiling Sun
- General Clinical Research Center, Nanjing First Hospital, Nanjing Medical University, Nanjing, 210006, People's Republic of China
| | - Shuo Li
- Department of Neurology, Affiliated ZhongDa Hospital, School of Medicine, Southeast University, No. 87 Dingjiaqiao Road, Nanjing, 210009, People's Republic of China
| | - Zhaohan Xu
- Department of Neurology, Nanjing First Hospital, Nanjing Medical University, No. 68 Changle Road, Nanjing, 210006, People's Republic of China
| | - Chengfang Liu
- Department of Neurology, Nanjing First Hospital, Nanjing Medical University, No. 68 Changle Road, Nanjing, 210006, People's Republic of China
| | - Pengyu Gong
- Department of Neurology, Nanjing First Hospital, Nanjing Medical University, No. 68 Changle Road, Nanjing, 210006, People's Republic of China
| | - Qiwen Deng
- Department of Neurology, Nanjing First Hospital, Nanjing Medical University, No. 68 Changle Road, Nanjing, 210006, People's Republic of China.
| | - Fuling Yan
- Department of Neurology, Affiliated ZhongDa Hospital, School of Medicine, Southeast University, No. 87 Dingjiaqiao Road, Nanjing, 210009, People's Republic of China.
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Bietar B, Zhou J, Lehmann C. Utility of intestinal intravital microscopy for the study of CNS injury-induced immunodepression syndrome (CIDS). Clin Hemorheol Microcirc 2021; 79:137-147. [PMID: 34487026 DOI: 10.3233/ch-219109] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/15/2022]
Abstract
BACKGROUND Stroke, traumatic brain injury, or other forms of central nervous system (CNS) injury initiate a local inflammatory response. Compensatory anti-inflammatory pathways are activated to limit secondary damage due to inflammation. The associated release of immunosuppressing neuromodulators can result in system-wide immune dysregulation (CNS injury-induced immune-depression syndrome -CIDS). OBJECTIVE To establish an experimental stroke model where CIDS can be studied by intravital microscopy (IVM). METHODS We used the photothrombotic stroke (PTS) model in C57BL/6 mice and studied its effects on peripheral immunity following challenge with lipopolysaccharide (LPS). Leukocyte activation, as well as capillary perfusion of the microcirculation, were assessed using intestinal intravital microscopy (IVM). RESULTS PTS caused a significant reduction in the number of adhering leukocytes in submucosal venules of the terminal ileum of mice challenged with LPS compared to LPS-challenged animals without stroke. Leukocyte rolling was also impacted by PTS in the submucosal venules. Following stroke, we also observed decreased mucosal functional capillary density (FCD). CONCLUSIONS Our results suggest that PTS with subsequent LPS challenge poses as a viable model to further study CIDS using intravital microscopy of the intestinal microcirculation.
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Affiliation(s)
- Bashir Bietar
- Department of Pharmacology, Dalhousie University, Halifax, NS, Canada
| | - Juan Zhou
- Department of Anesthesia, Pain Management & Perioperative Medicine, Dalhousie University, Halifax, NS, Canada
| | - Christian Lehmann
- Department of Pharmacology, Dalhousie University, Halifax, NS, Canada.,Department of Anesthesia, Pain Management & Perioperative Medicine, Dalhousie University, Halifax, NS, Canada
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Gwak MG, Chang SY. Gut-Brain Connection: Microbiome, Gut Barrier, and Environmental Sensors. Immune Netw 2021; 21:e20. [PMID: 34277110 PMCID: PMC8263213 DOI: 10.4110/in.2021.21.e20] [Citation(s) in RCA: 44] [Impact Index Per Article: 14.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/03/2021] [Revised: 06/09/2021] [Accepted: 06/12/2021] [Indexed: 02/08/2023] Open
Abstract
The gut is an important organ with digestive and immune regulatory function which consistently harbors microbiome ecosystem. The gut microbiome cooperates with the host to regulate the development and function of the immune, metabolic, and nervous systems. It can influence disease processes in the gut as well as extra-intestinal organs, including the brain. The gut closely connects with the central nervous system through dynamic bidirectional communication along the gut-brain axis. The connection between gut environment and brain may affect host mood and behaviors. Disruptions in microbial communities have been implicated in several neurological disorders. A link between the gut microbiota and the brain has long been described, but recent studies have started to reveal the underlying mechanism of the impact of the gut microbiota and gut barrier integrity on the brain and behavior. Here, we summarized the gut barrier environment and the 4 main gut-brain axis pathways. We focused on the important function of gut barrier on neurological diseases such as stress responses and ischemic stroke. Finally, we described the impact of representative environmental sensors generated by gut bacteria on acute neurological disease via the gut-brain axis.
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Affiliation(s)
- Min-Gyu Gwak
- Laboratory of Microbiology, College of Pharmacy, and Research Institute of Pharmaceutical Science and Technology (RIPST), Ajou University, Suwon 16499, Korea
| | - Sun-Young Chang
- Laboratory of Microbiology, College of Pharmacy, and Research Institute of Pharmaceutical Science and Technology (RIPST), Ajou University, Suwon 16499, Korea
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You XY, Zhang HY, Han X, Wang F, Zhuang PW, Zhang YJ. Intestinal Mucosal Barrier Is Regulated by Intestinal Tract Neuro-Immune Interplay. Front Pharmacol 2021; 12:659716. [PMID: 34135754 PMCID: PMC8201607 DOI: 10.3389/fphar.2021.659716] [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: 01/28/2021] [Accepted: 04/30/2021] [Indexed: 12/11/2022] Open
Abstract
Inflammatory bowel disease, irritable bowel syndrome and severe central nervous system injury can lead to intestinal mucosal barrier damage, which can cause endotoxin/enterobacteria translocation to induce infection and is closely related to the progression of metabolic diseases, cardiovascular and cerebrovascular diseases, tumors and other diseases. Hence, repairing the intestinal barrier represents a potential therapeutic target for many diseases. Enteral afferent nerves, efferent nerves and the intrinsic enteric nervous system (ENS) play key roles in regulating intestinal physiological homeostasis and coping with acute stress. Furthermore, innervation actively regulates immunity and induces inherent and adaptive immune responses through complex processes, such as secreting neurotransmitters or hormones and regulating their corresponding receptors. In addition, intestinal microorganisms and their metabolites play a regulatory role in the intestinal mucosal barrier. This paper primarily discusses the interactions between norepinephrine and β-adrenergic receptors, cholinergic anti-inflammatory pathways, nociceptive receptors, complex ENS networks, gut microbes and various immune cells with their secreted cytokines to summarize the key roles in regulating intestinal inflammation and improving mucosal barrier function.
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Affiliation(s)
- Xin-Yu You
- Tianjin Key Laboratory of Chinese medicine Pharmacology, Tianjin University of Traditional Chinese Medicine, Tianjin, China
| | - Han-Yu Zhang
- Tianjin Key Laboratory of Chinese medicine Pharmacology, Tianjin University of Traditional Chinese Medicine, Tianjin, China
| | - Xu Han
- Tianjin Key Laboratory of Chinese medicine Pharmacology, Tianjin University of Traditional Chinese Medicine, Tianjin, China
| | - Fang Wang
- Tianjin Key Laboratory of Chinese medicine Pharmacology, Tianjin University of Traditional Chinese Medicine, Tianjin, China
| | - Peng-Wei Zhuang
- Tianjin Key Laboratory of Chinese medicine Pharmacology, Tianjin University of Traditional Chinese Medicine, Tianjin, China.,State Key Laboratory of Component-based Chinese Medicine, Tianjin University of Traditional Chinese Medicine, Tianjin, China
| | - Yan-Jun Zhang
- Tianjin Key Laboratory of Chinese medicine Pharmacology, Tianjin University of Traditional Chinese Medicine, Tianjin, China.,State Key Laboratory of Component-based Chinese Medicine, Tianjin University of Traditional Chinese Medicine, Tianjin, China
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Jagdmann S, Berchtold D, Gutbier B, Witzenrath M, Meisel A, Meisel C, Dames C. Efficacy and safety of intratracheal IFN-γ treatment to reverse stroke-induced susceptibility to pulmonary bacterial infections. J Neuroimmunol 2021; 355:577568. [PMID: 33862420 DOI: 10.1016/j.jneuroim.2021.577568] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/30/2020] [Revised: 04/01/2021] [Accepted: 04/01/2021] [Indexed: 12/14/2022]
Abstract
Stroke-induced immunosuppression contributes to the development of stroke-associated pneumonia (SAP). Experiments in mice demonstrated that apoptosis of IFN-γ producing cells and reduced IFN-γ secretion resulted in impaired immune responses and the development of pneumonia after middle cerebral artery occlusion (MCAo). In the present study, we investigated the efficacy of intratracheal IFN-γ treatment to prevent SAP and demonstrated that modest benefits on pulmonary cytokine response in IFN-γ treated stroke mice did not prevent spontaneously developing infections and even slightly reduced bacterial clearance of aspirated pneumococci. Our results suggest that pulmonary IFN-γ treatment is not an effective preventive measure for SAP.
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Affiliation(s)
- Sandra Jagdmann
- Charité - Universitätsmedizin, Corporate member of Freie Universität Berlin, Humboldt-Universität zu Berlin, Berlin Institute of Health, Institute for Medical Immunology, Augustenburger Platz 1, Berlin 13353, Germany.
| | - Daniel Berchtold
- Charité - Universitätsmedizin, Corporate member of Freie Universität Berlin, Humboldt-Universität zu Berlin, Berlin Institute of Health, Department of Experimental Neurology, Charitéplatz 1, Berlin 10117, Germany.
| | - Birgitt Gutbier
- Charité - Universitätsmedizin, Corporate member of Freie Universität Berlin, Humboldt-Universität zu Berlin, Berlin Institute of Health, Division of Pulmonary Inflammation, Charitéplatz 1, Berlin 10117, Germany.
| | - Martin Witzenrath
- Charité - Universitätsmedizin, Corporate member of Freie Universität Berlin, Humboldt-Universität zu Berlin, Berlin Institute of Health, Division of Pulmonary Inflammation, Charitéplatz 1, Berlin 10117, Germany; Charité - Universitätsmedizin, Corporate member of Freie Universität Berlin, Humboldt-Universität zu Berlin, Berlin Institute of Health, Department of Infectious Diseases and Respiratory Medicine, Charitéplatz 1, Berlin 10117, Germany.
| | - Andreas Meisel
- Charité - Universitätsmedizin, Corporate member of Freie Universität Berlin, Humboldt-Universität zu Berlin, Berlin Institute of Health, Department of Experimental Neurology, Charitéplatz 1, Berlin 10117, Germany; Charité - Universitätsmedizin, Corporate member of Freie Universität Berlin, Humboldt-Universität zu Berlin, Berlin Institute of Health, Center for Stroke Research Berlin, Charitéplatz 1, Berlin 10117, Germany; Charité - Universitätsmedizin, Corporate member of Freie Universität Berlin, Humboldt-Universität zu Berlin, Berlin Institute of Health, Neurocure Cluster of Excellence, Charitéplatz 1, Berlin 10117, Germany; Charité - Universitätsmedizin, Corporate member of Freie Universität Berlin, Humboldt-Universität zu Berlin, Berlin Institute of Health, Department of Neurology, Charitéplatz 1, Berlin 10117, Germany.
| | - Christian Meisel
- Charité - Universitätsmedizin, Corporate member of Freie Universität Berlin, Humboldt-Universität zu Berlin, Berlin Institute of Health, Institute for Medical Immunology, Augustenburger Platz 1, Berlin 13353, Germany; Labor Berlin-Charité Vivantes, Sylter Str. 2, Berlin 13353, Germany.
| | - Claudia Dames
- Charité - Universitätsmedizin, Corporate member of Freie Universität Berlin, Humboldt-Universität zu Berlin, Berlin Institute of Health, Institute for Medical Immunology, Augustenburger Platz 1, Berlin 13353, Germany; Charité - Universitätsmedizin, Corporate member of Freie Universität Berlin, Humboldt-Universität zu Berlin, Berlin Institute of Health, Department of Experimental Neurology, Charitéplatz 1, Berlin 10117, Germany.
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Impact of Key Nicotinic AChR Subunits on Post-Stroke Pneumococcal Pneumonia. Vaccines (Basel) 2020; 8:vaccines8020253. [PMID: 32481512 PMCID: PMC7349987 DOI: 10.3390/vaccines8020253] [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: 04/30/2020] [Revised: 05/25/2020] [Accepted: 05/25/2020] [Indexed: 12/12/2022] Open
Abstract
Pneumonia is the most frequent severe medical complication after stroke. An overactivation of the cholinergic signaling after stroke contributes to immunosuppression and the development of spontaneous pneumonia caused by Gram-negative pathogens. The α7 nicotinic acetylcholine receptor (α7nAChR) has already been identified as an important mediator of the anti-inflammatory pathway after stroke. However, whether the α2, α5 and α9/10 nAChR expressed in the lung also play a role in suppression of pulmonary innate immunity after stroke is unknown. In the present study, we investigate the impact of various nAChRs on aspiration-induced pneumonia after stroke. Therefore, α2, α5, α7 and α9/10 nAChR knockout (KO) mice and wild type (WT) littermates were infected with Streptococcus pneumoniae (S. pneumoniae) three days after middle cerebral artery occlusion (MCAo). One day after infection pathogen clearance, cellularity in lung and spleen, cytokine secretion in bronchoalveolar lavage (BAL) and alveolar-capillary barrier were investigated. Here, we found that deficiency of various nAChRs does not contribute to an enhanced clearance of a Gram-positive pathogen causing post-stroke pneumonia in mice. In conclusion, these findings suggest that a single nAChR is not sufficient to mediate the impaired pulmonary defense against S. pneumoniae after experimental stroke.
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Abstract
Thousands of people are affected by central nervous system (CNS) dysfunctions each year, with stroke and spinal cord injury (SCI) being the most frequent causes. Although there is some evidence of partial CNS self-repair (via migration of neural stem cells to the injury zone and adult neurogenesis), due to restricted regeneration capacity in mammals, acute or chronic spinal cord injuries cannot be repaired completely. Therefore, to expand the availability of treatment options for SCI, research on highly regenerative animals has become essential. Among vertebrates, axolotl, a salamander species, has been emerging as a powerful model to explore the molecular mechanisms of regeneration due to its exceptional regenerative capacity. In this study, gene expression modulation for regenerative-capable neotenic axolotl during spinal cord regeneration has been investigated. Next-generation sequencing was applied for the collected regeneration samples at zero and seven days post-amputation (dpa). The data obtained from the analyzed samples revealed 363 genes differentially expressed, mostly downregulated, between zero dpa and seven dpa. The extracellular matrix, cell-cell adhesion, and immune system-related processes and pathways were enriched by gene ontology and the Kyoto Encyclopedia of Genes and Genomes (KEGG) pathway enrichment analyses. Based on these data, we conclude that the downregulation of immune system-related biological processes is crucial for spinal cord regeneration.
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