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Ooi K, Hu L, Feng Y, Han C, Ren X, Qian X, Huang H, Chen S, Shi Q, Lin H, Wang J, Zhu D, Wang R, Xia C. Sigma-1 Receptor Activation Suppresses Microglia M1 Polarization via Regulating Endoplasmic Reticulum-Mitochondria Contact and Mitochondrial Functions in Stress-Induced Hypertension Rats. Mol Neurobiol 2021; 58:6625-6646. [PMID: 34601668 DOI: 10.1007/s12035-021-02488-6] [Citation(s) in RCA: 20] [Impact Index Per Article: 6.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/19/2021] [Accepted: 07/08/2021] [Indexed: 12/31/2022]
Abstract
Exposure to stress plays a detrimental role in the pathogenesis of hypertension via neuroinflammation pathways. Microglial neuroinflammation in the rostral ventrolateral medulla (RVLM) exacerbates stress-induced hypertension (SIH) by increasing sympathetic hyperactivity. Mitochondria of microglia are the regulators of innate immune response. Sigma-1R (σ-1R) localizes to the mitochondria-associated membranes (MAMs) and regulates endoplasmic reticulum (ER) and mitochondria communication, in part through its chaperone activity. The present study aims to investigate the protective role of σ-1R on microglial-mediated neuroinflammation. Stress-induced hypertension (SIH) was induced in rats using electric foot shocks and intermittent noise. Arterial blood pressure (ABP), heart rate (HR), and renal sympathetic nerve activity (RSNA) were measured to evaluate the sympathetic nervous system (SNS) activities. SKF10047 (100 µM), an agonist of σ-1R, was administrated to rats, then σ-1R localization and MAM alterations were detected by immuno-electron microscopy. Mitochondrial calcium homeostasis was examined in primary microglia and/or BV-2 microglia cells. The effect of SKF10047 treatment on the mitochondrial respiratory function of cultured microglia was measured using a Seahorse Extracellular Flux Analyzer. Confocal microscopic images were performed to indicate mitochondrial dynamics. Stress reduces σ-1R's localization at the MAMs, leading to decreased ER-mitochondria contact and IP3R-GRP75-VDAC calcium transport complexes expression in the RVLM of rats. SKF10047 promotes the length and coverage of MAMs in the prorenin-treated microglia. Prorenin treatment increases mitoROS levels, and inhibits Ca2+ signalling between the two organelles, therefore negatively affects ATP production in BV2 cells, and these effects are reversed by SKF10047 treatment. We found mitochondrial hyperfusion and microglial M1 polarization in prorenin-treated microglia. SKF10047 suppresses microglial M1 polarization and RVLM neuroinflammation, subsequently ameliorates sympathetic hyperactivity in stress-induced hypertensive rats. Sigma-1 receptor activation suppresses microglia M1 polarization and neuroinflammation via regulating endoplasmic reticulum-mitochondria contact and mitochondrial functions in stress-induced hypertension rats.
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Affiliation(s)
- Kokwin Ooi
- Department of Physiology and Pathophysiology, School of Basic Medical Sciences, Fudan University, Shanghai, People's Republic of China
| | - Li Hu
- Department of Cardiovascular Diseases, Renji Hospital Affiliated To Shanghai Jiao Tong University School of Medicine, Shanghai, People's Republic of China
| | - Yi Feng
- Department of Integrative Medicine and Neurobiology, School of Basic Medical Sciences, Fudan University, Shanghai, 200032, People's Republic of China
| | - Chenzhi Han
- Department of Physiology and Pathophysiology, School of Basic Medical Sciences, Fudan University, Shanghai, People's Republic of China
| | - Xiaorong Ren
- Department of Physiology and Pathophysiology, School of Basic Medical Sciences, Fudan University, Shanghai, People's Republic of China
| | - Xinyi Qian
- Department of Physiology and Pathophysiology, School of Basic Medical Sciences, Fudan University, Shanghai, People's Republic of China
| | - Haofeng Huang
- Department of Physiology and Pathophysiology, School of Basic Medical Sciences, Fudan University, Shanghai, People's Republic of China
| | - Sijia Chen
- Department of Physiology and Pathophysiology, School of Basic Medical Sciences, Fudan University, Shanghai, People's Republic of China
| | - Qi Shi
- Department of Physiology and Pathophysiology, School of Basic Medical Sciences, Fudan University, Shanghai, People's Republic of China
| | - Hong Lin
- Department of Physiology and Pathophysiology, School of Basic Medical Sciences, Fudan University, Shanghai, People's Republic of China
| | - Jijiang Wang
- Department of Physiology and Pathophysiology, School of Basic Medical Sciences, Fudan University, Shanghai, People's Republic of China
| | - Danian Zhu
- Department of Physiology and Pathophysiology, School of Basic Medical Sciences, Fudan University, Shanghai, People's Republic of China
| | - Rui Wang
- Department of Cardiovascular Diseases, Yangpu District Central Hospital Affiliated to Tongji University School of Medicine, Shanghai, 200090, People's Republic of China.
| | - Chunmei Xia
- Department of Physiology and Pathophysiology, School of Basic Medical Sciences, Fudan University, Shanghai, People's Republic of China.
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Huang C, Rosencrans RF, Bugescu R, Vieira CP, Hu P, Adu-Agyeiwaah Y, Gamble KL, Longhini ALF, Fuller PM, Leinninger GM, Grant MB. Depleting hypothalamic somatostatinergic neurons recapitulates diabetic phenotypes in mouse brain, bone marrow, adipose and retina. Diabetologia 2021; 64:2575-2588. [PMID: 34430981 PMCID: PMC9004546 DOI: 10.1007/s00125-021-05549-6] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 04/01/2021] [Accepted: 06/11/2021] [Indexed: 12/01/2022]
Abstract
AIMS/HYPOTHESIS Hypothalamic inflammation and sympathetic nervous system hyperactivity are hallmark features of the metabolic syndrome and type 2 diabetes. Hypothalamic inflammation may aggravate metabolic and immunological pathologies due to extensive sympathetic activation of peripheral tissues. Loss of somatostatinergic (SST) neurons may contribute to enhanced hypothalamic inflammation. METHODS The present data show that leptin receptor-deficient (db/db) mice exhibit reduced hypothalamic SST neurons, particularly in the periventricular nucleus. We model this finding, using adeno-associated virus delivery of diphtheria toxin subunit A (DTA) driven by an SST-cre system to deplete these neurons in Sstcre/gfp mice (SST-DTA). RESULTS SST-DTA mice exhibit enhanced hypothalamic c-Fos expression and brain inflammation as demonstrated by microglial and astrocytic activation. Bone marrow from SST-DTA mice undergoes skewed haematopoiesis, generating excess granulocyte-monocyte progenitors and increased proinflammatory (C-C chemokine receptor type 2; CCR2hi) monocytes. SST-DTA mice exhibited a 'diabetic retinopathy-like' phenotype: reduced visual function by optokinetic response (0.4 vs 0.25 cycles/degree; SST-DTA vs control mice); delayed electroretinogram oscillatory potentials; and increased percentages of retinal monocytes. Finally, mesenteric visceral adipose tissue from SST-DTA mice was resistant to catecholamine-induced lipolysis, displaying 50% reduction in isoprenaline (isoproterenol)-induced lipolysis compared with control littermates. Importantly, hyperglycaemia was not observed in SST-DTA mice. CONCLUSIONS/INTERPRETATION The isolated reduction in hypothalamic SST neurons was able to recapitulate several hallmark features of type 2 diabetes in disease-relevant tissues.
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Affiliation(s)
- Chao Huang
- Department of Ophthalmology, University of Alabama at Birmingham, Birmingham, AL, USA
| | - Robert F Rosencrans
- Department of Ophthalmology, University of Alabama at Birmingham, Birmingham, AL, USA
| | - Raluca Bugescu
- Department of Physiology, Michigan State University, East Lansing, MI, USA
| | - Cristiano P Vieira
- Department of Ophthalmology, University of Alabama at Birmingham, Birmingham, AL, USA
| | - Ping Hu
- Department of Ophthalmology, University of Alabama at Birmingham, Birmingham, AL, USA
| | - Yvonne Adu-Agyeiwaah
- Department of Ophthalmology, University of Alabama at Birmingham, Birmingham, AL, USA
| | - Karen L Gamble
- Department of Psychiatry and Neurobehavioral Neurobiology, University of Alabama at Birmingham, Birmingham, AL, USA
| | - Ana Leda F Longhini
- Department of Ophthalmology, University of Alabama at Birmingham, Birmingham, AL, USA
| | - Patrick M Fuller
- Department of Neurology, Beth Israel Deaconess Medical Center and Division of Sleep Medicine, Harvard Medical School, Boston, MA, USA
| | - Gina M Leinninger
- Department of Physiology, Michigan State University, East Lansing, MI, USA
| | - Maria B Grant
- Department of Ophthalmology, University of Alabama at Birmingham, Birmingham, AL, USA.
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Association of Brain-Gut Peptides with Inflammatory Cytokines in Moyamoya Disease. Mediators Inflamm 2020; 2020:5847478. [PMID: 32410857 PMCID: PMC7204157 DOI: 10.1155/2020/5847478] [Citation(s) in RCA: 14] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/19/2019] [Revised: 02/28/2020] [Accepted: 04/06/2020] [Indexed: 01/06/2023] Open
Abstract
Systemic inflammation has been shown to play a pivotal role in the pathogenesis of moyamoya disease (MMD). Brain-gut peptides exhibit regulatory effects in the secretion of proinflammatory cytokines. To investigate the association between brain-gut peptides and inflammation in the occurrence of MMD, 41 patients with MMD, as well as 74 age- and sex-matched healthy individuals were enrolled. The levels of four brain-gut peptides (vasoactive intestinal polypeptide (VIP), cholecystokinin (CCK), somatostatin (SST), substance P (SP)) and three proinflammatory cytokines (interleukin-1β (IL-1β), tumor necrosis factor-α (TNF-α), IL-12) in the serum and cerebrospinal fluid (CSF) were measured using the enzyme-linked immunosorbent assay. The associations between brain-gut peptides and proinflammatory cytokines were estimated according to the multiple linear regression and correlation analyses. MMD patients exhibited significantly lower levels of VIP, CCK, and SST and higher levels of IL-1β, TNF-α, and IL-12 in the serum compared with healthy controls. Multiple logistic regression analysis showed that decreased VIP, CCK, and SST levels were independent predictors of the occurrence of MMD. Negative correlations were observed between the VIP and proinflammatory cytokines, including IL-1β, TNF-α, and IL-12 (serum vs. CSF). Significant negative correlations were also found between CCK and IL-1β, as well as IL-12 (serum vs. CSF). SST was negatively correlated with IL-1β and TNF-α in the serum and IL-1β only in the CSF. In addition, the levels of VIP, CCK, SST, and proinflammatory cytokines IL-1β and TNF-α in the serum were correlated with those measured in the CSF. Collectively, lower levels of VIP, CCK, and SST may be associated with the pathogenesis of MMD and act as clinically useful biomarkers along with the levels of proinflammatory cytokines.
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Hu L, Zhang S, Ooi K, Wu X, Wu J, Cai J, Sun Y, Wang J, Zhu D, Chen F, Xia C. Microglia-Derived NLRP3 Activation Mediates the Pressor Effect of Prorenin in the Rostral Ventrolateral Medulla of Stress-Induced Hypertensive Rats. Neurosci Bull 2020; 36:475-492. [PMID: 32242284 PMCID: PMC7186257 DOI: 10.1007/s12264-020-00484-9] [Citation(s) in RCA: 24] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/11/2019] [Accepted: 12/14/2019] [Indexed: 02/07/2023] Open
Abstract
Increased microglial activation and neuroinflammation within autonomic brain regions such as the rostral ventrolateral medulla (RVLM) have been implicated in stress-induced hypertension (SIH). Prorenin, a member of the brain renin-angiotensin system (RAS), can directly activate microglia. The present study aimed to investigate the effects of prorenin on microglial activation in the RVLM of SIH rats. Rats were subjected to intermittent electric foot-shocks plus noise, this stress was administered for 2 h twice daily for 15 consecutive days, and mean arterial pressure (MAP) and renal sympathetic nerve activity (RSNA) were monitored. The results showed that MAP and RSNA were augmented, and this paralleled increased pro-inflammatory phenotype (M1) switching. Prorenin and its receptor (PRR) expression and the NLR family pyrin domain containing 3 (NLRP3) activation were increased in RVLM of SIH rats. In addition, PLX5622 (a microglial depletion agent), MCC950 (a NLRP3 inhibitor), and/or PRO20 (a (Pro)renin receptor antagonist) had antihypertensive effects in the rats. The NLRP3 expression in the RVLM was decreased in SIH rats treated with PLX5622. Mito-tracker staining showed translocation of NLRP3 from mitochondria to the cytoplasm in prorenin-stimulated microglia. Prorenin increased the ROS-triggering M1 phenotype-switching and NLRP3 activation, while MCC950 decreased the M1 polarization. In conclusion, upregulated prorenin in the RVLM may be involved in the pathogenesis of SIH, mediated by activation of the microglia-derived NLRP3 inflammasome. The link between prorenin and NLRP3 in microglia provides insights for the treatment of stress-related hypertension.
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Affiliation(s)
- Li Hu
- Laboratory of Neuropharmacology and Neurotoxicology, Shanghai Key Laboratory of Bio-Energy Crops, College of Life Science, Shanghai University, Shanghai, 200444, China
| | - Shutian Zhang
- Department of Physiology and Pathophysiology, Basic Medicine College, Fudan University, Shanghai, 200032, China
| | - Kokwin Ooi
- Department of Physiology and Pathophysiology, Basic Medicine College, Fudan University, Shanghai, 200032, China
| | - Xuehai Wu
- Department of Neurosurgery, Huashan Hospital, Fudan University, Shanghai, 200040, China
| | - Jiaxiang Wu
- Laboratory of Neuropharmacology and Neurotoxicology, Shanghai Key Laboratory of Bio-Energy Crops, College of Life Science, Shanghai University, Shanghai, 200444, China
| | - Jian Cai
- Department of Neurology, Renji Hospital, Shanghai Jiaotong University, Shanghai, 200240, China
| | - Yinggang Sun
- Department of Cardiovascular Diseases, Xinhua Hospital Affiliated to Shanghai Jiao Tong University School of Medicine, Shanghai, 200025, China
| | - Jijiang Wang
- Department of Physiology and Pathophysiology, Basic Medicine College, Fudan University, Shanghai, 200032, China
| | - Danian Zhu
- Department of Physiology and Pathophysiology, Basic Medicine College, Fudan University, Shanghai, 200032, China
| | - Fuxue Chen
- Laboratory of Neuropharmacology and Neurotoxicology, Shanghai Key Laboratory of Bio-Energy Crops, College of Life Science, Shanghai University, Shanghai, 200444, China.
| | - Chunmei Xia
- Department of Physiology and Pathophysiology, Basic Medicine College, Fudan University, Shanghai, 200032, China.
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Neuropeptides and Microglial Activation in Inflammation, Pain, and Neurodegenerative Diseases. Mediators Inflamm 2017; 2017:5048616. [PMID: 28154473 PMCID: PMC5244030 DOI: 10.1155/2017/5048616] [Citation(s) in RCA: 143] [Impact Index Per Article: 20.4] [Reference Citation Analysis] [Abstract] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/19/2016] [Revised: 11/26/2016] [Accepted: 12/05/2016] [Indexed: 12/15/2022] Open
Abstract
Microglial cells are responsible for immune surveillance within the CNS. They respond to noxious stimuli by releasing inflammatory mediators and mounting an effective inflammatory response. This is followed by release of anti-inflammatory mediators and resolution of the inflammatory response. Alterations to this delicate process may lead to tissue damage, neuroinflammation, and neurodegeneration. Chronic pain, such as inflammatory or neuropathic pain, is accompanied by neuroimmune activation, and the role of glial cells in the initiation and maintenance of chronic pain has been the subject of increasing research over the last two decades. Neuropeptides are small amino acidic molecules with the ability to regulate neuronal activity and thereby affect various functions such as thermoregulation, reproductive behavior, food and water intake, and circadian rhythms. Neuropeptides can also affect inflammatory responses and pain sensitivity by modulating the activity of glial cells. The last decade has witnessed growing interest in the study of microglial activation and its modulation by neuropeptides in the hope of developing new therapeutics for treating neurodegenerative diseases and chronic pain. This review summarizes the current literature on the way in which several neuropeptides modulate microglial activity and response to tissue damage and how this modulation may affect pain sensitivity.
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Torika N, Asraf K, Danon A, Apte RN, Fleisher-Berkovich S. Telmisartan Modulates Glial Activation: In Vitro and In Vivo Studies. PLoS One 2016; 11:e0155823. [PMID: 27187688 PMCID: PMC4871324 DOI: 10.1371/journal.pone.0155823] [Citation(s) in RCA: 45] [Impact Index Per Article: 5.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/17/2015] [Accepted: 05/04/2016] [Indexed: 12/16/2022] Open
Abstract
The circulating renin-angiotensin system (RAS), including the biologically active angiotensin II, is a fundamental regulatory mechanism of blood pressure conserved through evolution. Angiotensin II components of the RAS have also been identified in the brain. In addition to pro-inflammatory cytokines, neuromodulators, such as angiotensin II can induce (through angiotensin type 1 receptor (AT1R)) some of the inflammatory actions of brain glial cells and influence brain inflammation. Moreover, in Alzheimer’s disease (AD) models, where neuroinflammation occurs, increased levels of cortical AT1Rs have been shown. Still, the precise role of RAS in neuroinflammation is not completely clear. The overall aim of the present study was to elucidate the role of RAS in the modulation of glial functions and AD pathology. To reach this goal, the specific aims of the present study were a. to investigate the long term effect of telmisartan (AT1R blocker) on tumor necrosis factor-α (TNF-α), interleukin 1-β (IL1-β) and nitric oxide (NO) release from glial cells. b. to examine the effect of intranasally administered telmisartan on amyloid burden and microglial activation in 5X familial AD (5XFAD) mice. Telmisartan effects in vivo were compared to those of perindopril (angiotensin converting enzyme inhibitor). Long-term-exposure of BV2 microglia to telmisartan significantly decreased lipopolysaccharide (LPS) -induced NO, inducible NO synthase, TNF-α and IL1-β synthesis. The effect of Telmisartan on NO production in BV2 cells was confirmed also in primary neonatal rat glial cells. Intranasal administration of telmisartan (1 mg/kg/day) for up to two months significantly reduced amyloid burden and CD11b expression (a marker for microglia) both in the cortex and hipoccampus of 5XFAD. Based on the current view of RAS and our data, showing reduced amyloid burden and glial activation in the brains of 5XFAD transgenic mice, one may envision potential intervention with the progression of glial activation and AD by using AT1R blockers.
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Affiliation(s)
- Nofar Torika
- Department of Clinical Biochemistry and Pharmacology, Ben-Gurion University of the Negev, Beer-Sheva P.O.B 653, Israel
| | - Keren Asraf
- Department of Clinical Biochemistry and Pharmacology, Ben-Gurion University of the Negev, Beer-Sheva P.O.B 653, Israel
| | - Abraham Danon
- Department of Clinical Biochemistry and Pharmacology, Ben-Gurion University of the Negev, Beer-Sheva P.O.B 653, Israel
| | - Ron N. Apte
- Department of Microbiology and Immunology, Ben-Gurion University of the Negev, Beer-Sheva P.O.B 653, Israel
| | - Sigal Fleisher-Berkovich
- Department of Clinical Biochemistry and Pharmacology, Ben-Gurion University of the Negev, Beer-Sheva P.O.B 653, Israel
- * E-mail:
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Lu Y, He M, Zhang Y, Xu S, Zhang L, He Y, Chen C, Liu C, Pi H, Yu Z, Zhou Z. Differential pro-inflammatory responses of astrocytes and microglia involve STAT3 activation in response to 1800 MHz radiofrequency fields. PLoS One 2014; 9:e108318. [PMID: 25275372 PMCID: PMC4183530 DOI: 10.1371/journal.pone.0108318] [Citation(s) in RCA: 31] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/28/2014] [Accepted: 08/19/2014] [Indexed: 12/23/2022] Open
Abstract
Microglia and astrocytes play important role in maintaining the homeostasis of central nervous system (CNS). Several CNS impacts have been postulated to be associated with radiofrequency (RF) electromagnetic fields exposure. Given the important role of inflammation in neural physiopathologic processes, we investigated the pro-inflammatory responses of microglia and astrocytes and the involved mechanism in response to RF fields. Microglial N9 and astroglial C8-D1A cells were exposed to 1800 MHz RF for different time with or without pretreatment with STAT3 inhibitor. Microglia and astrocytes were activated by RF exposure indicated by up-regulated CD11b and glial fibrillary acidic protein (GFAP). However, RF exposure induced differential pro-inflammatory responses in astrocytes and microglia, characterized by different expression and release profiles of IL-1β, TNF-α, IL-6, PGE2, nitric oxide (NO), inducible nitric oxide synthase (iNOS) and cyclooxygenase 2 (COX2). Moreover, the RF exposure activated STAT3 in microglia but not in astrocytes. Furthermore, the STAT3 inhibitor Stattic ameliorated the RF-induced release of pro-inflammatory cytokines in microglia but not in astrocytes. Our results demonstrated that RF exposure differentially induced pro-inflammatory responses in microglia and astrocytes, which involved differential activation of STAT3 in microglia and astrocytes. Our data provide novel insights into the potential mechanisms of the reported CNS impacts associated with mobile phone use and present STAT3 as a promising target to protect humans against increasing RF exposure.
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Affiliation(s)
- Yonghui Lu
- Department of Occupational Health, Key Lab of Medical Protection for Electromagnetic Radiation, Ministry of Education of China, Third Military Medical University, Chongqing, China
| | - Mindi He
- Department of Occupational Health, Key Lab of Medical Protection for Electromagnetic Radiation, Ministry of Education of China, Third Military Medical University, Chongqing, China
| | - Yang Zhang
- Department of Laboratory Medicine, Southwest Hospital, Third Military Medical University, Chongqing, China
| | - Shangcheng Xu
- Department of Occupational Health, Key Lab of Medical Protection for Electromagnetic Radiation, Ministry of Education of China, Third Military Medical University, Chongqing, China
| | - Lei Zhang
- Department of Occupational Health, Key Lab of Medical Protection for Electromagnetic Radiation, Ministry of Education of China, Third Military Medical University, Chongqing, China
| | - Yue He
- Department of Neurosurgery, Tongji Hospital, Tongji Medical College, Huazhong University of Science and Technology, Wuhan, China
| | - Chunhai Chen
- Department of Occupational Health, Key Lab of Medical Protection for Electromagnetic Radiation, Ministry of Education of China, Third Military Medical University, Chongqing, China
| | - Chuan Liu
- Department of Occupational Health, Key Lab of Medical Protection for Electromagnetic Radiation, Ministry of Education of China, Third Military Medical University, Chongqing, China
| | - Huifeng Pi
- Department of Occupational Health, Key Lab of Medical Protection for Electromagnetic Radiation, Ministry of Education of China, Third Military Medical University, Chongqing, China
| | - Zhengping Yu
- Department of Occupational Health, Key Lab of Medical Protection for Electromagnetic Radiation, Ministry of Education of China, Third Military Medical University, Chongqing, China
| | - Zhou Zhou
- Department of Occupational Health, Key Lab of Medical Protection for Electromagnetic Radiation, Ministry of Education of China, Third Military Medical University, Chongqing, China
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Zemtsova I, Görg B, Keitel V, Bidmon HJ, Schrör K, Häussinger D. Microglia activation in hepatic encephalopathy in rats and humans. Hepatology 2011; 54:204-15. [PMID: 21452284 DOI: 10.1002/hep.24326] [Citation(s) in RCA: 120] [Impact Index Per Article: 9.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
Abstract
UNLABELLED Astrocytes play an important role in the pathogenesis of hepatic encephalopathy (HE) and ammonia toxicity, whereas little is known about microglia and neuroinflammation under these conditions. We therefore studied the effects of ammonia on rat microglia in vitro and in vivo and analyzed markers of neuroinflammation in post mortem brain tissue from patients with cirrhosis with and without HE and non-cirrhotic controls. In cultured rat microglia, ammonia stimulated cell migration and induced oxidative stress and an up-regulation of the microglial activation marker ionized calcium-binding adaptor molecule-1 (Iba-1). Up-regulation of Iba-1 was also found in the cerebral cortex from acutely ammonia-intoxicated rats and in the cerebral cortex from patients with cirrhosis who have HE, but not from patients with cirrhosis who do not have HE. However, ammonia had no effect on microglial glutamate release, prostaglandin synthesis, and messenger RNA (mRNA) levels of inducible nitric oxide synthase (iNOS), cyclooxygenase-2 (COX-2), and the proinflammatory cytokines interleukin (IL)-1α/β, tumor necrosis factor α, or IL-6, whereas in cultured astrocytes ammonia induced the release of glutamate, prostaglandins, and increased IL-1β mRNA. mRNA and protein expression of iNOS and COX-2 or mRNA expression of proinflammatory cytokines and chemokine monocyte chemoattractive protein-1 in cerebral cortex from patients with liver cirrhosis and HE were not different from those found in patients with cirrhosis who did not have HE or control patients without cirrhosis. CONCLUSION These data suggest that microglia become activated in experimental hyperammonemia and HE in humans and may contribute to the generation of oxidative stress. However, HE in patients with liver cirrhosis is not associated with an up-regulation of inflammatory cytokines in cerebral cortex, despite microglia activation.
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Affiliation(s)
- Irina Zemtsova
- Clinic for Gastroenterology, Hepatology, and Infectiology, Heinrich-Heine University, Düsseldorf, Germany
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