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Damascena HL, Silveira WAA, Castro MS, Fontes W. Neutrophil Activated by the Famous and Potent PMA (Phorbol Myristate Acetate). Cells 2022; 11:cells11182889. [PMID: 36139464 PMCID: PMC9496763 DOI: 10.3390/cells11182889] [Citation(s) in RCA: 23] [Impact Index Per Article: 11.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/24/2022] [Revised: 08/28/2022] [Accepted: 08/29/2022] [Indexed: 11/16/2022] Open
Abstract
This review will briefly outline the major signaling pathways in PMA-activated neutrophils. PMA is widely used to understand neutrophil pathways and formation of NETs. PMA activates PKC; however, we highlight some isoforms that contribute to specific functions. PKC α, β and δ contribute to ROS production while PKC βII and PKC ζ are involved in cytoskeleton remodeling. Actin polymerization is important for the chemotaxis of neutrophils and its remodeling is connected to ROS balance. We suggest that, although ROS and production of NETs are usually observed together in PMA-activated neutrophils, there might be a regulatory mechanism balancing both. Interestingly, we suggest that serine proteases might determine the PAD4 action. PAD4 could be responsible for the activation of the NF-κB pathway that leads to IL-1β release, triggering the cleavage of gasdermin D by serine proteases such as elastase, leading to pore formation contributing to release of NETs. On the other hand, when serine proteases are inhibited, NETs are formed by citrullination through the PAD4 pathway. This review puts together results from the last 31 years of research on the effects of PMA on the neutrophil and proposes new insights on their interpretation.
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Mishra H, Mishra PK, Iqbal Z, Jaggi M, Madaan A, Bhuyan K, Gupta N, Gupta N, Vats K, Verma R, Talegaonkar S. Co-Delivery of Eugenol and Dacarbazine by Hyaluronic Acid-Coated Liposomes for Targeted Inhibition of Survivin in Treatment of Resistant Metastatic Melanoma. Pharmaceutics 2019; 11:E163. [PMID: 30987266 PMCID: PMC6523131 DOI: 10.3390/pharmaceutics11040163] [Citation(s) in RCA: 28] [Impact Index Per Article: 5.6] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/28/2019] [Revised: 03/15/2019] [Accepted: 03/18/2019] [Indexed: 12/15/2022] Open
Abstract
While melanoma remains a challenge for oncologists, possibilities are being continuously explored to fight resistant metastatic melanoma more effectively. Eugenol is reported to inhibit survivin protein in breast cancer cells. Survivin is also overexpressed by melanoma cells, and is known to impart resistance to them against chemotherapy-induced apoptosis. To be able to fight resistant melanoma, we formulated hyaluronic acid (HA)-coated liposomes loaded with an effective combination of anti-melanoma agents (Dacarbazine and Eugenol), using a solvent injection method. Quality-by-Design (QbD) was applied to optimize and obtain a final formulation with the desired quality attributes, and within an acceptable size range. The optimized formulation was then subjected to performance analysis in cell lines. Coated-Dacarbazine Eugenol Liposomes were found to possess 95.08% cytotoxicity at a dacarbazine concentration of 0.5 µg/mL, while Dacarbazine Solution showed only 10.20% cytotoxicity at the same concentration. The number of late apoptotic cells was also found to be much higher (45.16% vs. 8.43%). Furthermore, migration assay and proliferation study also revealed significantly higher inhibition of cell migration and proliferation by Coated-Dacarbazine Eugenol Liposomes, signifying its potential against metastasis. Thus, surface-functionalized dacarbazine- and eugenol-loaded liposomes hold great promise against resistant and aggressive metastatic melanoma, with much less unwanted cytotoxicity and reduced doses of the chemotherapeutic agent.
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Affiliation(s)
- Harshita Mishra
- Departmant of Pharmaceutics, School of Pharmaceutical Education and Research, Jamia Hamdard, New Delhi 110062, India.
| | - Pawan Kumar Mishra
- Department of Wood Processing, Mendel University in Brno, 61300 Brno, Czech Republic.
| | - Zeenat Iqbal
- Departmant of Pharmaceutics, School of Pharmaceutical Education and Research, Jamia Hamdard, New Delhi 110062, India.
| | - Manu Jaggi
- Dabur Research Foundation, Ghaziabad 201010, India.
| | - Alka Madaan
- Dabur Research Foundation, Ghaziabad 201010, India.
| | - Kimi Bhuyan
- Dabur Research Foundation, Ghaziabad 201010, India.
| | - Namita Gupta
- Dabur Research Foundation, Ghaziabad 201010, India.
| | - Neha Gupta
- Dabur Research Foundation, Ghaziabad 201010, India.
| | - Karnika Vats
- Dabur Research Foundation, Ghaziabad 201010, India.
| | - Ritu Verma
- Dabur Research Foundation, Ghaziabad 201010, India.
| | - Sushama Talegaonkar
- Departmant of Pharmaceutics, School of Pharmaceutical Education and Research, Jamia Hamdard, New Delhi 110062, India.
- Department of Pharmaceutics, Delhi Pharmaceutical Sciences and Research University, Govt. of NCT of Delhi, Pushp Vihar, New Delhi 110017, India.
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Xu C, Shi Q, Zhang L, Zhao H. High molecular weight hyaluronan attenuates fine particulate matter-induced acute lung injury through inhibition of ROS-ASK1-p38/JNK-mediated epithelial apoptosis. ENVIRONMENTAL TOXICOLOGY AND PHARMACOLOGY 2018; 59:190-198. [PMID: 29625389 DOI: 10.1016/j.etap.2018.03.020] [Citation(s) in RCA: 52] [Impact Index Per Article: 8.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/03/2018] [Revised: 03/27/2018] [Accepted: 03/28/2018] [Indexed: 06/08/2023]
Abstract
Inhalation of fine particulate matter (PM2.5) is asscoiated with lung injury. High molecular weight hyaluronan (HMW-HA) is an essential constituent of extracellular matrix (ECM), exhibiting anti-oxidative and anti-inflammatory properties when administered by injection, inhalation, nebulization or gene delivery of HA synthases. The aim of the present study is to determine whether HMW-HA alleviates PM2.5-induced acute lung injury (ALI) and investigate the underlying mechanisms. We observed that HMW-HA suppressed pathological injury, inflammation, oxidative stress, edema and epithelial damage caused by PM2.5 in the lungs of the rats. The protective mechanism of HMW-HA was further explored in vitro. The results elucidated that reactive oxygen species (ROS) was involved in PM2.5-induced cell apoptosis, and HMW-HA mitigated the oxidative potential of PM2.5, subsequently inhibiting phosphorylation of ASK1 at Thr845, downstream phosphorylation of p38 and JNK, and eventual apoptosis. Our study indicates that HMW-HA is a promising strategy in the prevention of PM2.5-induced pulmonary damage.
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Affiliation(s)
- Chenming Xu
- Collaborative Innovation Center of Yangtze River Delta Region Green Pharmaceuticals, Zhejiang University of Technology, PR China
| | - Qiwen Shi
- Collaborative Innovation Center of Yangtze River Delta Region Green Pharmaceuticals, Zhejiang University of Technology, PR China.
| | - Leifang Zhang
- Collaborative Innovation Center of Yangtze River Delta Region Green Pharmaceuticals, Zhejiang University of Technology, PR China
| | - Hang Zhao
- Collaborative Innovation Center of Yangtze River Delta Region Green Pharmaceuticals, Zhejiang University of Technology, PR China
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Host and pathogen hyaluronan signal through human siglec-9 to suppress neutrophil activation. J Mol Med (Berl) 2015; 94:219-33. [PMID: 26411873 DOI: 10.1007/s00109-015-1341-8] [Citation(s) in RCA: 54] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/03/2015] [Revised: 08/30/2015] [Accepted: 09/03/2015] [Indexed: 10/23/2022]
Abstract
UNLABELLED Inhibitory CD33-related Siglec receptors regulate immune cell activation upon engaging ubiquitous sialic acids (Sias) on host cell surface glycans. Through molecular mimicry, Sia-expressing pathogen group B Streptococcus binds inhibitory human Siglec-9 (hSiglec-9) to blunt neutrophil activation and promote bacterial survival. We unexpectedly discovered that hSiglec-9 also specifically binds high molecular weight hyaluronan (HMW-HA), another ubiquitous host glycan, through a region of its terminal Ig-like V-set domain distinct from the Sia-binding site. HMW-HA recognition by hSiglec-9 limited neutrophil extracellular trap (NET) formation, oxidative burst, and apoptosis, defining HMW-HA as a regulator of neutrophil activation. However, the pathogen group A Streptococcus (GAS) expresses a HMW-HA capsule that engages hSiglec-9, blocking NET formation and oxidative burst, thereby promoting bacterial survival. Thus, a single inhibitory lectin receptor detects two distinct glycan "self-associated molecular patterns" to maintain neutrophil homeostasis, and two leading human bacterial pathogens have independently evolved molecular mimicry to exploit this immunoregulatory mechanism. KEY MESSAGE HMW-HA is the first example of a non-sialic acid containing glycan to be recognized by CD33-related Siglecs. HMW-HA engagement of hSiglec-9 attenuates neutrophil activation. Group A Streptococcus exploits hSiglec-9 recognition via its polysaccharide HMW-HA capsule to subvert neutrophil killing.
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Marki A, Esko JD, Pries AR, Ley K. Role of the endothelial surface layer in neutrophil recruitment. J Leukoc Biol 2015; 98:503-15. [PMID: 25979432 DOI: 10.1189/jlb.3mr0115-011r] [Citation(s) in RCA: 88] [Impact Index Per Article: 9.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/11/2015] [Accepted: 03/25/2015] [Indexed: 12/15/2022] Open
Abstract
Neutrophil recruitment in most tissues is limited to postcapillary venules, where E- and P-selectins are inducibly expressed by venular endothelial cells. These molecules support neutrophil rolling via binding of PSGL-1 and other ligands on neutrophils. Selectins extend ≤ 38 nm above the endothelial plasma membrane, and PSGL-1 extends to 50 nm above the neutrophil plasma membrane. However, endothelial cells are covered with an ESL composed of glycosaminoglycans that is ≥ 500 nm thick and has measurable resistance against compression. The neutrophil surface is also covered with a surface layer. These surface layers would be expected to completely shield adhesion molecules; thus, neutrophils should not be able to roll and adhere. However, in the cremaster muscle and in many other models investigated using intravital microscopy, neutrophils clearly roll, and their rolling is easily and quickly induced. This conundrum was thought to be resolved by the observation that the induction of selectins is accompanied by ESL shedding; however, ESL shedding only partially reduces the ESL thickness (to 200 nm) and thus is insufficient to expose adhesion molecules. In addition to its antiadhesive functions, the ESL also presents neutrophil arrest-inducing chemokines. ESL heparan sulfate can also bind L-selectin expressed by the neutrophils, which contributes to rolling and arrest. We conclude that ESL has both proadhesive and antiadhesive functions. However, most previous studies considered either only the proadhesive or only the antiadhesive effects of the ESL. An integrated model for the role of the ESL in neutrophil rolling, arrest, and transmigration is needed.
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Affiliation(s)
- Alex Marki
- *Division of Inflammation Biology, La Jolla Institute for Allergy and Immunology, La Jolla, California, USA; Department of Cellular and Molecular Medicine, University of California, San Diego, La Jolla, California, USA; and Department of Physiology and Center for Cardiovascular Research, Charite, Berlin, Germany
| | - Jeffrey D Esko
- *Division of Inflammation Biology, La Jolla Institute for Allergy and Immunology, La Jolla, California, USA; Department of Cellular and Molecular Medicine, University of California, San Diego, La Jolla, California, USA; and Department of Physiology and Center for Cardiovascular Research, Charite, Berlin, Germany
| | - Axel R Pries
- *Division of Inflammation Biology, La Jolla Institute for Allergy and Immunology, La Jolla, California, USA; Department of Cellular and Molecular Medicine, University of California, San Diego, La Jolla, California, USA; and Department of Physiology and Center for Cardiovascular Research, Charite, Berlin, Germany
| | - Klaus Ley
- *Division of Inflammation Biology, La Jolla Institute for Allergy and Immunology, La Jolla, California, USA; Department of Cellular and Molecular Medicine, University of California, San Diego, La Jolla, California, USA; and Department of Physiology and Center for Cardiovascular Research, Charite, Berlin, Germany
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Mack JA, Feldman RJ, Itano N, Kimata K, Lauer M, Hascall VC, Maytin EV. Enhanced inflammation and accelerated wound closure following tetraphorbol ester application or full-thickness wounding in mice lacking hyaluronan synthases Has1 and Has3. J Invest Dermatol 2012; 132:198-207. [PMID: 21850020 PMCID: PMC3360468 DOI: 10.1038/jid.2011.248] [Citation(s) in RCA: 58] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
Abstract
Hyaluronan (HA) is an abundant matrix molecule, the function of which in the skin remains to be fully defined. To explore the roles of HA in cutaneous injury responses, double-knockout mice (abbreviated as Has1/3 null) that lack two HA synthase enzymes (Has1 and Has3), but still express functional Has2, were used in two types of experiments: (i) application of 12-O-tetradecanoylphorbol-13-acetate (TPA) and (ii) full-thickness wounding of the skin. Uninjured Has1/3-null mice were phenotypically normal. However, after TPA, the accumulation of HA that normally occurs in wild-type epidermis was blunted in Has1/3-null epidermis. In excisional wound-healing experiments, wound closure was significantly faster in Has1/3 null than in wild-type mice. Coincident with this abnormal wound healing, a marked decrease in epidermal and dermal HA and a marked increase in neutrophil efflux from cutaneous blood vessels were observed in Has1/3-null skin relative to wild-type skin. Has1/3-null wounds displayed an earlier onset of myofibroblast differentiation. In summary, selective loss of Has1 and Has3 leads to a proinflammatory milieu that favors recruitment of neutrophils and other inflammation-related changes in the dermis.
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Affiliation(s)
- Judith A. Mack
- Dept of Biomedical Engineering, Lerner Research Institute, Cleveland Clinic, Cleveland, OH, USA
- Dept of Dermatology, Dermatology and Plastic Surgery Institute, Cleveland Clinic, Cleveland, OH
| | - Ron J. Feldman
- Dept of Biomedical Engineering, Lerner Research Institute, Cleveland Clinic, Cleveland, OH, USA
- Dept of Dermatology, Dermatology and Plastic Surgery Institute, Cleveland Clinic, Cleveland, OH
| | - Naoki Itano
- Dept of Molecular Biosciences, Kyoto Sangyo University, Japan
| | - Koji Kimata
- Research Complex for Medicine Frontiers, Aichi Medical University, Aichi, Japan
| | - Mark Lauer
- Dept of Biomedical Engineering, Lerner Research Institute, Cleveland Clinic, Cleveland, OH, USA
| | - Vincent C. Hascall
- Dept of Biomedical Engineering, Lerner Research Institute, Cleveland Clinic, Cleveland, OH, USA
| | - Edward V. Maytin
- Dept of Biomedical Engineering, Lerner Research Institute, Cleveland Clinic, Cleveland, OH, USA
- Dept of Dermatology, Dermatology and Plastic Surgery Institute, Cleveland Clinic, Cleveland, OH
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Rho BH, Kwon KY, Choi WI. The Effect of Hyaluronan Treatment in Endotoxemic Rats. Tuberc Respir Dis (Seoul) 2011. [DOI: 10.4046/trd.2011.70.5.390] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/24/2022] Open
Affiliation(s)
- Byung Hak Rho
- Department of Diagnostic Radiology, Keimyung University School of Medicine, Daegu, Korea
| | - Kun Young Kwon
- Department of Pathology, Keimyung University School of Medicine, Daegu, Korea
| | - Won-Il Choi
- Department of Internal Medicine, Keimyung University School of Medicine, Daegu, Korea
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HUANG PM, SYRKINA O, YU L, DEDAJ R, ZHAO H, SHIEDLIN A, LIU YY, GARG H, QUINN DA, HALES CA. High MW hyaluronan inhibits smoke inhalation-induced lung injury and improves survival. Respirology 2010; 15:1131-9. [DOI: 10.1111/j.1440-1843.2010.01829.x] [Citation(s) in RCA: 28] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/31/2022]
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Vigetti D, Genasetti A, Karousou E, Viola M, Moretto P, Clerici M, Deleonibus S, De Luca G, Hascall VC, Passi A. Proinflammatory cytokines induce hyaluronan synthesis and monocyte adhesion in human endothelial cells through hyaluronan synthase 2 (HAS2) and the nuclear factor-kappaB (NF-kappaB) pathway. J Biol Chem 2010; 285:24639-45. [PMID: 20522558 DOI: 10.1074/jbc.m110.134536] [Citation(s) in RCA: 94] [Impact Index Per Article: 6.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/19/2023] Open
Abstract
Chronic inflammation is now accepted to have a critical role in the onset of several diseases as well as in vascular pathology, where macrophage transformation into foam cells contributes in atherosclerotic plaque formation. Endothelial cells (EC) have a critical function in recruitment of immune cells, and proinflammatory cytokines drive the specific expression of several adhesion proteins. During inflammatory responses several cells produce hyaluronan matrices that promote monocyte/macrophage adhesion through interactions with the hyaluronan receptor CD44 present on inflammatory cell surfaces. In this study, we used human umbilical chord vein endothelial cells (HUVECs) as a model to study the mechanism that regulates hyaluronan synthesis after treatment with proinflammatory cytokines. We found that interleukin 1beta and tumor necrosis factors alpha and beta, but not transforming growth factors alpha and beta, strongly induced HA synthesis by NF-kappaB pathway. This signaling pathway mediated hyaluronan synthase 2 (HAS2) mRNA expression without altering other glycosaminoglycan metabolism. Moreover, we verified that U937 monocyte adhesion on stimulated HUVECs depends strongly on hyaluronan, and transfection with short interference RNA of HAS2 abrogates hyaluronan synthesis revealing the critical role of HAS2 in this process.
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Affiliation(s)
- Davide Vigetti
- Dipartimento di Scienze Biomediche Sperimentali e Cliniche, Università degli Studi dell'Insubria, via JH Dunant 5, 21100 Varese, Italy
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Butler LM, Rainger GE, Nash GB. A role for the endothelial glycosaminoglycan hyaluronan in neutrophil recruitment by endothelial cells cultured for prolonged periods. Exp Cell Res 2009; 315:3433-41. [PMID: 19716819 PMCID: PMC2777247 DOI: 10.1016/j.yexcr.2009.08.012] [Citation(s) in RCA: 28] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/12/2009] [Revised: 08/11/2009] [Accepted: 08/21/2009] [Indexed: 01/10/2023]
Abstract
Glycosaminoglycans (GAGs) presented on the surface of endothelial cells (ECs) are believed to influence leukocyte recruitment during inflammation, but their roles remain uncertain. Here we report an in vitro model of prolonged culture of human EC in which the contributions of heparan sulphate (HS) and hyaluronan (HA) to the process of neutrophil recruitment could be studied. Previously, we reported that increasing EC culture duration (up to 20 days) enhanced neutrophil recruitment in response to low dose (1 U/ml) but not high dose (100 U/ml) of tumour necrosis factor-α (TNF). Here we found that HS and HA were present at much higher levels on the surface of day 20 cultures than day 3 cultures. Neutrophil recruitment on both day 3 and day 20 ECs was mediated through CXCR chemokine receptors and interleukin-8 (IL-8). In addition, mRNA levels for TNF receptors, signalling pathway constituents, adhesion receptors, and chemokines involved in neutrophil recruitment were similar for day 3 and day 20 ECs. To test whether the enhanced neutrophil recruitment on day 20 EC was mediated by GAGs, they were removed enzymatically. Removal of HA (but not HS) inhibited neutrophil recruitment, as did antibody blockade of CD44, a counter-receptor for HA on neutrophils. Supernatants from hyaluronidase-treated day 20 ECs were more potent in activating neutrophils than supernatants from untreated EC. Thus, HA has a role in neutrophil recruitment that is revealed in long-term cultures where it increases potency of response to sub-optimal levels of TNF. This effect appears to occur through a dual mechanism involving chemokine presentation and interaction with CD44.
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Affiliation(s)
- Lynn M Butler
- School of Clinical and Experimental Medicine, College of Medical and Dental Sciences, The Medical School, The University of Birmingham, Birmingham, UK.
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Nadkarni PP, Kulkarni GS, Cerreta JM, Ma S, Cantor JO. DICHOTOMOUS EFFECT OF AEROSOLIZED HYALURONAN IN A HAMSTER MODEL OF ENDOTOXIN-INDUCED LUNG INJURY. Exp Lung Res 2009; 31:807-18. [PMID: 16684714 DOI: 10.1080/01902140600574942] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/01/2023]
Abstract
Inhalation of aerosolized low-molecular-weight (150-kDa) hyaluronan (HA) was previously shown by this laboratory to prevent experimentally induced pulmonary emphysema without associated toxicity. Nevertheless, other investigators have found that low-molecular-weight HA may be proinflammatory, prompting the authors to determine if aerosolized HA could possibly enhance pulmonary inflammation in a different model of lung injury involving intratracheal instillation of endotoxin to hamsters. Results indicate that exposure to HA following endotoxin administration significantly increased lung inflammation, whereas pretreatment with HA had the opposite effect.
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Affiliation(s)
- Priya P Nadkarni
- School of Pharmacy and Allied Health Sciences, St. John's University, New York, NY 11439, USA
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Rampon C, Weiss N, Deboux C, Chaverot N, Miller F, Buchet D, Tricoire-Leignel H, Cazaubon S, Baron-Van Evercooren A, Couraud PO. Molecular mechanism of systemic delivery of neural precursor cells to the brain: assembly of brain endothelial apical cups and control of transmigration by CD44. Stem Cells 2008; 26:1673-82. [PMID: 18450824 DOI: 10.1634/stemcells.2008-0122] [Citation(s) in RCA: 56] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/17/2022]
Abstract
Systemically injected neural precursor cells (NPCs) were unexpectedly shown to reach the cerebral parenchyma and induce recovery in various diffuse brain pathologies, including animal models of multiple sclerosis. However, the molecular mechanisms supporting NPC migration across brain endothelium remain elusive. Brain endothelium constitutes the blood-brain barrier, which uniquely controls the access of drugs and trafficking of cells, including leukocytes, from the blood to the brain. Taking advantage of the availability of in vitro models of human and rat blood-brain barrier developed in our laboratory and validated by us and others, we show here that soluble hyaluronic acid, the major ligand of the adhesion molecule CD44, as well as anti-CD44 blocking antibodies, largely prevents NPC adhesion to and migration across brain endothelium in inflammatory conditions. We present further evidence that NPCs, surprisingly, induce the formation of apical cups at the surface of brain endothelial cells, enriched in CD44 and other adhesion molecules, thus hijacking the endothelial signaling recently shown to be involved in leukocyte extravasation. These results demonstrate the pivotal role of CD44 in the trans-endothelial migration of NPCs across brain endothelial cells: we propose that they may help design new strategies for the delivery of therapeutic NPCs to the brain by systemic administration.
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