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El-Saie A, Shivanna B. Novel Strategies to Reduce Pulmonary Hypertension in Infants With Bronchopulmonary Dysplasia. Front Pediatr 2020; 8:201. [PMID: 32457857 PMCID: PMC7225259 DOI: 10.3389/fped.2020.00201] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 12/12/2019] [Accepted: 04/02/2020] [Indexed: 01/10/2023] Open
Abstract
Bronchopulmonary dysplasia (BPD) is a developmental lung disorder of preterm infants primarily caused by the failure of host defense mechanisms to prevent tissue injury and facilitate repair. This disorder is the most common complication of premature birth, and its incidence remains unchanged over the past few decades. Additionally, BPD increases long-term cardiopulmonary and neurodevelopmental morbidities of preterm infants. Pulmonary hypertension (PH) is a common morbidity of BPD. Importantly, the presence of PH increases both the short- and long-term morbidities and mortality in BPD infants. Further, there are no curative therapies for this complex disease. Besides providing an overview of the pathogenesis and diagnosis of PH associated with BPD, we have attempted to comprehensively review and summarize the current literature on the interventions to prevent and/or mitigate BPD and PH in preclinical studies. Our goal was to provide insight into the therapies that have a high translational potential to meaningfully manage BPD patients with PH.
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Affiliation(s)
- Ahmed El-Saie
- Department of Pediatrics, Section of Neonatology, Baylor College of Medicine, Texas Children's Hospital, Houston, TX, United States
| | - Binoy Shivanna
- Department of Pediatrics, Section of Neonatology, Baylor College of Medicine, Texas Children's Hospital, Houston, TX, United States
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Poon K. Behavioral Feeding Circuit: Dietary Fat-Induced Effects of Inflammatory Mediators in the Hypothalamus. Front Endocrinol (Lausanne) 2020; 11:591559. [PMID: 33324346 PMCID: PMC7726204 DOI: 10.3389/fendo.2020.591559] [Citation(s) in RCA: 12] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 08/04/2020] [Accepted: 10/23/2020] [Indexed: 12/19/2022] Open
Abstract
Excessive dietary fat intake has extensive impacts on several physiological systems and can lead to metabolic and nonmetabolic disease. In animal models of ingestion, exposure to a high fat diet during pregnancy predisposes offspring to increase intake of dietary fat and causes increase in weight gain that can lead to obesity, and without intervention, these physiological and behavioral consequences can persist for several generations. The hypothalamus is a region of the brain that responds to physiological hunger and fullness and contains orexigenic neuropeptide systems that have long been associated with dietary fat intake. The past fifteen years of research show that prenatal exposure to a high fat diet increases neurogenesis of these neuropeptide systems in offspring brain and are correlated to behavioral changes that induce a pro-consummatory and obesogenic phenotype. Current research has uncovered several potential molecular mechanisms by which excessive dietary fat alters the hypothalamus and involve dietary fatty acids, the immune system, gut microbiota, and transcriptional and epigenetic changes. This review will examine the current knowledge of dietary fat-associated changes in the hypothalamus and the potential pathways involved in modifying the development of orexigenic peptide neurons that lead to changes in ingestive behavior, with a special emphasis on inflammation by chemokines.
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Guerra K, Bryan C, Dapaah-Siakwan F, Sammour I, Drummond S, Zambrano R, Chen P, Huang J, Sharma M, Shrager S, Benny M, Wu S, Young KC. Intra-tracheal administration of a naked plasmid expressing stromal derived factor-1 improves lung structure in rodents with experimental bronchopulmonary dysplasia. Respir Res 2019; 20:255. [PMID: 31718614 PMCID: PMC6852969 DOI: 10.1186/s12931-019-1224-6] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/08/2019] [Accepted: 10/29/2019] [Indexed: 12/15/2022] Open
Abstract
Background Bronchopulmonary dysplasia (BPD) is characterized by alveolar simplification and disordered angiogenesis. Stromal derived factor-1 (SDF-1) is a chemokine which modulates cell migration, proliferation, and angiogenesis. Here we tested the hypothesis that intra-tracheal (IT) administration of a naked plasmid DNA expressing SDF-1 would attenuate neonatal hyperoxia-induced lung injury in an experimental model of BPD, by promoting angiogenesis. Design/methods Newborn Sprague-Dawley rat pups (n = 18–20/group) exposed to room air (RA) or hyperoxia (85% O2) from postnatal day (P) 1 to 14 were randomly assigned to receive IT a naked plasmid expressing SDF-1, JVS-100 (Juventas Therapeutics, Cleveland, Ohio) or placebo (PL) on P3. Lung alveolarization, angiogenesis, inflammation, vascular remodeling and pulmonary hypertension (PH) were assessed on P14. PH was determined by measuring right ventricular systolic pressure (RVSP) and the weight ratio of the right to left ventricle + septum (RV/LV + S). Capillary tube formation in SDF-1 treated hyperoxia-exposed human pulmonary microvascular endothelial cells (HPMEC) was determined by matrigel assay. Data is expressed as mean ± SD and analyzed by two-way ANOVA. Results Exposure of neonatal pups to 14 days of hyperoxia decreased lung SDF-1 gene expression. Moreover, whilst hyperoxia exposure inhibited capillary tube formation in HPMEC, SDF-1 treatment increased tube length and branching in HPMEC. PL-treated hyperoxia-exposed pups had decreased alveolarization and lung vascular density. This was accompanied by an increase in RVSP, RV/LV + S, pulmonary vascular remodeling and inflammation. In contrast, IT JVS-100 improved lung structure, reduced inflammation, PH and vascular remodeling. Conclusions Intratracheal administration of a naked plasmid expressing SDF-1 improves alveolar and vascular structure in an experimental model of BPD. These findings suggest that therapies which modulate lung SDF-1 expression may have beneficial effects in preterm infants with BPD.
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Affiliation(s)
- Kasonya Guerra
- Department of Pediatrics, University of Miami Miller School of Medicine, 1580 NW 10th Avenue RM-344, Miami, FL, 33136, USA.,Batchelor Children's Research Institute, University of Miami Miller School of Medicine, 1580 NW 10th Avenue RM-344, Miami, FL, 33136, USA
| | - Carleene Bryan
- Department of Pediatrics, University of Miami Miller School of Medicine, 1580 NW 10th Avenue RM-344, Miami, FL, 33136, USA.,Batchelor Children's Research Institute, University of Miami Miller School of Medicine, 1580 NW 10th Avenue RM-344, Miami, FL, 33136, USA
| | - Frederick Dapaah-Siakwan
- Department of Pediatrics, University of Miami Miller School of Medicine, 1580 NW 10th Avenue RM-344, Miami, FL, 33136, USA.,Batchelor Children's Research Institute, University of Miami Miller School of Medicine, 1580 NW 10th Avenue RM-344, Miami, FL, 33136, USA
| | - Ibrahim Sammour
- Department of Pediatrics, University of Miami Miller School of Medicine, 1580 NW 10th Avenue RM-344, Miami, FL, 33136, USA.,Batchelor Children's Research Institute, University of Miami Miller School of Medicine, 1580 NW 10th Avenue RM-344, Miami, FL, 33136, USA
| | - Shelly Drummond
- Department of Pediatrics, University of Miami Miller School of Medicine, 1580 NW 10th Avenue RM-344, Miami, FL, 33136, USA.,Batchelor Children's Research Institute, University of Miami Miller School of Medicine, 1580 NW 10th Avenue RM-344, Miami, FL, 33136, USA
| | - Ronald Zambrano
- Department of Pediatrics, University of Miami Miller School of Medicine, 1580 NW 10th Avenue RM-344, Miami, FL, 33136, USA.,Batchelor Children's Research Institute, University of Miami Miller School of Medicine, 1580 NW 10th Avenue RM-344, Miami, FL, 33136, USA
| | - Pingping Chen
- Department of Pediatrics, University of Miami Miller School of Medicine, 1580 NW 10th Avenue RM-344, Miami, FL, 33136, USA.,Batchelor Children's Research Institute, University of Miami Miller School of Medicine, 1580 NW 10th Avenue RM-344, Miami, FL, 33136, USA
| | - Jian Huang
- Department of Pediatrics, University of Miami Miller School of Medicine, 1580 NW 10th Avenue RM-344, Miami, FL, 33136, USA.,Batchelor Children's Research Institute, University of Miami Miller School of Medicine, 1580 NW 10th Avenue RM-344, Miami, FL, 33136, USA
| | - Mayank Sharma
- Department of Pediatrics, University of Miami Miller School of Medicine, 1580 NW 10th Avenue RM-344, Miami, FL, 33136, USA.,Batchelor Children's Research Institute, University of Miami Miller School of Medicine, 1580 NW 10th Avenue RM-344, Miami, FL, 33136, USA
| | - Sebastian Shrager
- Department of Pediatrics, University of Miami Miller School of Medicine, 1580 NW 10th Avenue RM-344, Miami, FL, 33136, USA
| | - Merline Benny
- Department of Pediatrics, University of Miami Miller School of Medicine, 1580 NW 10th Avenue RM-344, Miami, FL, 33136, USA.,Batchelor Children's Research Institute, University of Miami Miller School of Medicine, 1580 NW 10th Avenue RM-344, Miami, FL, 33136, USA
| | - Shu Wu
- Department of Pediatrics, University of Miami Miller School of Medicine, 1580 NW 10th Avenue RM-344, Miami, FL, 33136, USA.,Batchelor Children's Research Institute, University of Miami Miller School of Medicine, 1580 NW 10th Avenue RM-344, Miami, FL, 33136, USA
| | - Karen C Young
- Department of Pediatrics, University of Miami Miller School of Medicine, 1580 NW 10th Avenue RM-344, Miami, FL, 33136, USA. .,Batchelor Children's Research Institute, University of Miami Miller School of Medicine, 1580 NW 10th Avenue RM-344, Miami, FL, 33136, USA. .,The Interdisciplinary Stem Cell Institute, University of Miami Miller School of Medicine, 1580 NW 10th Avenue RM-344, Miami, FL, 33136, USA.
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Gilbert W, Bragg R, Elmansi AM, McGee-Lawrence ME, Isales CM, Hamrick MW, Hill WD, Fulzele S. Stromal cell-derived factor-1 (CXCL12) and its role in bone and muscle biology. Cytokine 2019; 123:154783. [PMID: 31336263 PMCID: PMC6948927 DOI: 10.1016/j.cyto.2019.154783] [Citation(s) in RCA: 24] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/11/2019] [Revised: 07/08/2019] [Accepted: 07/16/2019] [Indexed: 02/07/2023]
Abstract
Musculoskeletal disorders are the leading cause of disability worldwide; two of the most prevalent of which are osteoporosis and sarcopenia. Each affect millions in the aging population across the world and the associated morbidity and mortality contributes to billions of dollars in annual healthcare cost. Thus, it is important to better understand the underlying pathologic mechanisms of the disease process. Regulatory chemokine, CXCL12, and its receptor, CXCR4, are recognized to be essential in the recruitment, localization, maintenance, development and differentiation of progenitor stem cells of the musculoskeletal system. CXCL12 signaling results in the development and functional ability of osteoblasts, osteoclasts, satellite cells and myoblasts critical to maintaining musculoskeletal homeostasis. Interestingly, one suggested pathologic mechanism of osteoporosis and sarcopenia is a decline in the regenerative capacity of musculoskeletal progenitor stem cells. Thus, because CXCL12 is critical to progenitor function, a disruption in the CXCL12 signaling axis might play a distinct role in these pathological processes. Therefore, in this article, we perform a review of CXCL12, its physiologic and pathologic function in bone and muscle, and potential targets for therapeutic development.
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Affiliation(s)
- William Gilbert
- Department of Orthopaedic Surgery, Augusta University, Augusta, GA 30912, United States
| | - Robert Bragg
- Department of Orthopaedic Surgery, Augusta University, Augusta, GA 30912, United States
| | - Ahmed M Elmansi
- Department of Pathology and Laboratory Medicine, Medical University of South Carolina, Charleston, SC 29403, United States
| | - Meghan E McGee-Lawrence
- Department of Orthopaedic Surgery, Augusta University, Augusta, GA 30912, United States; Cell Biology and Anatomy, Augusta University, Augusta, GA 30912, United States
| | - Carlos M Isales
- Department of Orthopaedic Surgery, Augusta University, Augusta, GA 30912, United States; Department of Medicine, Augusta University, Augusta, GA 30912, United States
| | - Mark W Hamrick
- Department of Orthopaedic Surgery, Augusta University, Augusta, GA 30912, United States; Cell Biology and Anatomy, Augusta University, Augusta, GA 30912, United States
| | - William D Hill
- Department of Pathology and Laboratory Medicine, Medical University of South Carolina, Charleston, SC 29403, United States; Ralph H Johnson Veterans Affairs Medical Center, Charleston, SC 29403, United States
| | - Sadanand Fulzele
- Department of Orthopaedic Surgery, Augusta University, Augusta, GA 30912, United States; Cell Biology and Anatomy, Augusta University, Augusta, GA 30912, United States.
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Stromal derived factor-1 mediates the lung regenerative effects of mesenchymal stem cells in a rodent model of bronchopulmonary dysplasia. Respir Res 2017; 18:137. [PMID: 28701189 PMCID: PMC5506612 DOI: 10.1186/s12931-017-0620-z] [Citation(s) in RCA: 37] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/23/2017] [Accepted: 07/03/2017] [Indexed: 02/08/2023] Open
Abstract
Background Mesenchymal stem cells (MSCs) attenuate lung injury in experimental models of bronchopulmonary dysplasia (BPD). Stromal derived factor-1 (SDF-1), a chemokine secreted by MSCs, modulates angiogenesis and stem cell recruitment. Here we tested the hypothesis that SDF-1 mediates MSC protective effects in experimental BPD by modulating angiogenesis. Methods SDF-1 was knocked down in MSCs using lentiviral vectors carrying anti-SDF-1 short hairpin RNA (MSC-SDF KD). Non-silencing short hairpin RNA was used as control (MSC-NS control). Newborn rats exposed to normoxia or hyperoxia (FiO2 = 0.85) for 3 weeks, were randomly assigned to receive a single intra-tracheal injection (IT) of MSC-NS control or MSC-SDF KD (1 × 106 cells/50 μl) or placebo on postnatal day 7. The degree of alveolarization, lung angiogenesis, inflammation, and pulmonary hypertension (PH) were assessed at postnatal day 21. Results Administration of IT MSC-NS control improved lung alveolarization, angiogenesis and inflammation, and attenuated PH in newborn rats with hyperoxia-induced lung injury (HILI). In contrast, knockdown of SDF-1 in MSCs significantly reduced their beneficial effects on alveolarization, angiogenesis, inflammation and PH. Conclusions The therapeutic benefits of MSCs in neonatal HILI are in part mediated by SDF-1, through anti-inflammatory and angiogenesis promoting mechanisms. Therapies directly targeting this chemokine may provide a novel strategy for the treatment of BPD.
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Inhibition of SDF-1 receptors CXCR4 and CXCR7 attenuates acute pulmonary inflammation via the adenosine A 2B-receptor on blood cells. Cell Death Dis 2017; 8:e2832. [PMID: 28542132 PMCID: PMC5520683 DOI: 10.1038/cddis.2016.482] [Citation(s) in RCA: 32] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/26/2016] [Revised: 11/10/2016] [Accepted: 12/16/2016] [Indexed: 12/13/2022]
Abstract
Acute pulmonary inflammation is characterized by migration of polymorphonuclear neutrophils into the different compartments of the lung. Recent studies showed evidence that the chemokine stromal cell-derived factor (SDF)-1 and its receptors CXCR4 and CXCR7 influence migration of immune cells and their activity was linked to adenosine concentrations. We investigated the particular role of CXCR4- and CXCR7-inhibition and the potential link to the adenosine A2B-receptor, which plays an important anti-inflammatory role in the lung. After LPS-inhalation for 45 minutes, administration of the CXCR4-inhibitor (AMD3100) decreased transendothelial and transepithelial migration, whereas CXCR7-antagonism influenced epithelial migration exclusively. In A2B−/− mice, no anti-inflammatory effects were detectible through either one of the agents. Using chimeric mice, we identified A2B on hematopoietic cells to be crucial for these anti-inflammatory effects of CXCR4/7-inhibition. Both inhibitors decreased TNFα, IL6, CXCL1 and CXCL2/3 levels in the bronchoalveolar lavage of wild type mice, while not influencing the chemokine release in A2B−/− mice. Inflammation augmented the expression of both receptors and their inhibition increased A2B-levels upon inflammation. In vitro assays with human epithelium/endothelium confirmed our in vivo findings. During inflammation, inhibition of CXCR4- and CXCR7-receptors prevented microvascular permeability in wild type but not in A2B−/− mice, highlighting the pivotal role of an active A2B-receptor in this setting. The combination of both inhibitors had a synergistic effect in preventing capillary leakage. In conclusion, we determined the pivotal role of CXCR4- and CXCR7-inhibition in acute pulmonary inflammation, which depended on A2B-receptor signalling.
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Ngamsri KC, Müller A, Bösmüller H, Gamper-Tsigaras J, Reutershan J, Konrad FM. The Pivotal Role of CXCR7 in Stabilization of the Pulmonary Epithelial Barrier in Acute Pulmonary Inflammation. THE JOURNAL OF IMMUNOLOGY 2017; 198:2403-2413. [PMID: 28188248 DOI: 10.4049/jimmunol.1601682] [Citation(s) in RCA: 24] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/28/2016] [Accepted: 01/12/2017] [Indexed: 11/19/2022]
Abstract
Acute pulmonary inflammation is still a frightening complication in intensive care units and has a high mortality. Specific treatment is not available, and many details of the pathomechanism remain unclear. The recently discovered chemokine receptor CXCR7 and its ligand stromal cell-derived factor (SDF)-1 are known to be involved in inflammation. We chose to investigate the detailed role of CXCR7 in a murine model of LPS inhalation. Inflammation increased pulmonary expression of CXCR7, and the receptor was predominantly expressed on pulmonary epithelium and on polymorphonuclear neutrophil (PMNs) after transepithelial migration into the alveolar space. Specific inhibition of CXCR7 reduced transepithelial PMN migration by affecting the expression of adhesion molecules. CXCR7 antagonism reduced the most potent PMN chemoattractants CXCL1 and CXCL2/3. After inhibiting CXCR7, NF-κB phosphorylation was reduced in lungs of mice, tight junction formation increased, and protein concentration in the bronchoalveolar lavage diminished, showing the impact of CXCR7 on stabilizing microvascular permeability. In vitro studies with human cells confirmed the pivotal role of CXCR7 in pulmonary epithelium. Immunofluorescence of human lungs confirmed our in vivo data and showed an increase of the expression of CXCR7 in pulmonary epithelium. Highlighting the clinical potential of CXCR7 antagonism, nebulization of the agent before and after the inflammation showed impressive anti-inflammatory effects. Additional CXCR7 inhibition potentiated the effect of SDF-1 antagonism, most probably by downregulating SDF-1 and the second receptor of the chemokine (CXCR4) expression. In conclusion, our data identified the pivotal role of the receptor CXCR7 in pulmonary inflammation with a predominant effect on the pulmonary epithelium and PMNs.
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Affiliation(s)
- Kristian-Christos Ngamsri
- Department of Anesthesiology and Intensive Care Medicine, University Hospital of Tübingen, 72076 Tübingen, Germany
| | - Anika Müller
- Department of Anesthesiology and Intensive Care Medicine, University Hospital of Tübingen, 72076 Tübingen, Germany
| | - Hans Bösmüller
- Department of Pathology, University Hospital of Tübingen, 72076 Tübingen, Germany; and
| | - Jutta Gamper-Tsigaras
- Department of Anesthesiology and Intensive Care Medicine, University Hospital of Tübingen, 72076 Tübingen, Germany
| | - Jörg Reutershan
- Department of Anesthesiology and Intensive Care Medicine, Bayreuth Hospital, 95445 Bayreuth, Germany
| | - Franziska M Konrad
- Department of Anesthesiology and Intensive Care Medicine, University Hospital of Tübingen, 72076 Tübingen, Germany;
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Debruin EJ, Hughes MR, Sina C, Liu A, Cait J, Jian Z, Lopez M, Lo B, Abraham T, McNagny KM. Podocalyxin regulates murine lung vascular permeability by altering endothelial cell adhesion. PLoS One 2014; 9:e108881. [PMID: 25303643 PMCID: PMC4193771 DOI: 10.1371/journal.pone.0108881] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/27/2014] [Accepted: 08/26/2014] [Indexed: 12/11/2022] Open
Abstract
Despite the widespread use of CD34-family sialomucins (CD34, podocalyxin and endoglycan) as vascular endothelial cell markers, there is remarkably little known of their vascular function. Podocalyxin (gene name Podxl), in particular, has been difficult to study in adult vasculature as germ-line deletion of podocalyxin in mice leads to kidney malformations and perinatal death. We generated mice that conditionally delete podocalyxin in vascular endothelial cells (Podxl(ΔEC) mice) to study the homeostatic role of podocalyxin in adult mouse vessels. Although Podxl(ΔEC) adult mice are viable, their lungs display increased lung volume and changes to the matrix composition. Intriguingly, this was associated with increased basal and inflammation-induced pulmonary vascular permeability. To further investigate the etiology of these defects, we isolated mouse pulmonary endothelial cells. Podxl(ΔEC) endothelial cells display mildly enhanced static adhesion to fibronectin but spread normally when plated on fibronectin-coated transwells. In contrast, Podxl(ΔEC) endothelial cells exhibit a severely impaired ability to spread on laminin and, to a lesser extent, collagen I coated transwells. The data suggest that, in endothelial cells, podocalyxin plays a previously unrecognized role in maintaining vascular integrity, likely through orchestrating interactions with extracellular matrix components and basement membranes, and that this influences downstream epithelial architecture.
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Affiliation(s)
- Erin J. Debruin
- The Biomedical Research Centre, University of British Columbia, Vancouver, BC, Canada
| | - Michael R. Hughes
- The Biomedical Research Centre, University of British Columbia, Vancouver, BC, Canada
| | - Christina Sina
- The Biomedical Research Centre, University of British Columbia, Vancouver, BC, Canada
| | - Alex Liu
- The Biomedical Research Centre, University of British Columbia, Vancouver, BC, Canada
| | - Jessica Cait
- The Biomedical Research Centre, University of British Columbia, Vancouver, BC, Canada
| | - Zhiqi Jian
- The Biomedical Research Centre, University of British Columbia, Vancouver, BC, Canada
| | - Martin Lopez
- The Biomedical Research Centre, University of British Columbia, Vancouver, BC, Canada
| | - Bernard Lo
- The Biomedical Research Centre, University of British Columbia, Vancouver, BC, Canada
| | - Thomas Abraham
- UBC James Hogg Research Centre, Institute for Heart + Lung Health, Vancouver, BC, Canada
- Penn State College of Medicine, Penn State University, Hershey, Pennsylvania, United States of America
| | - Kelly M. McNagny
- The Biomedical Research Centre, University of British Columbia, Vancouver, BC, Canada
- * E-mail:
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Ray P, Lewin SA, Mihalko LA, Lesher-Perez SC, Takayama S, Luker KE, Luker GD. Secreted CXCL12 (SDF-1) forms dimers under physiological conditions. Biochem J 2012; 442:433-42. [PMID: 22142194 PMCID: PMC4419379 DOI: 10.1042/bj20111341] [Citation(s) in RCA: 48] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/17/2022]
Abstract
Chemokine CXCL12 (CXC chemokine ligand 12) signalling through CXCR (CXC chemokine receptor) 4 and CXCR7 has essential functions in development and underlies diseases including cancer, atherosclerosis and autoimmunity. Chemokines may form homodimers that regulate receptor binding and signalling, but previous studies with synthetic CXCL12 have produced conflicting evidence for homodimerization. We used bioluminescence imaging with GL (Gaussia luciferase) fusions to investigate dimerization of CXCL12 secreted from mammalian cells. Using column chromatography and GL complementation, we established that CXCL12 was secreted from mammalian cells as both monomers and dimers. Secreted CXCL12 also formed homodimers in the extracellular space. Monomeric CXCL12 preferentially activated CXCR4 signalling through Gαi and Akt, whereas dimeric CXCL12 more effectively promoted recruitment of β-arrestin 2 to CXCR4 and chemotaxis of CXCR4-expressing breast cancer cells. We also showed that CXCR7 preferentially sequestered monomeric CXCL12 from the extracellular space and had minimal effects on dimeric CXCL12 in cell-based assays and an orthotopic tumour xenograft model of human breast cancer. These studies establish that CXCL12 secreted from mammalian cells forms homodimers under physiological conditions. Since monomeric and dimeric CXCL12 have distinct effects on cell signalling and function, our results have important implications for ongoing efforts to target CXCL12 pathways for therapy.
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Affiliation(s)
- Paramita Ray
- Center for Molecular Imaging, Department of Radiology, University of Michigan, Ann Arbor, MI, USA
| | - Sarah A. Lewin
- Center for Molecular Imaging, Department of Radiology, University of Michigan, Ann Arbor, MI, USA
| | - Laura Anne Mihalko
- Center for Molecular Imaging, Department of Radiology, University of Michigan, Ann Arbor, MI, USA
| | | | - Shuichi Takayama
- Department of Biomedical Engineering, University of Michigan, Ann Arbor, MI, USA
| | - Kathryn E. Luker
- Center for Molecular Imaging, Department of Radiology, University of Michigan, Ann Arbor, MI, USA
| | - Gary D. Luker
- Center for Molecular Imaging, Department of Radiology, University of Michigan, Ann Arbor, MI, USA
- Department of Microbiology and Immunology, University of Michigan, Ann Arbor, MI, USA
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Ghosh MC, Makena PS, Gorantla V, Sinclair SE, Waters CM. CXCR4 regulates migration of lung alveolar epithelial cells through activation of Rac1 and matrix metalloproteinase-2. Am J Physiol Lung Cell Mol Physiol 2012; 302:L846-56. [PMID: 22345572 DOI: 10.1152/ajplung.00321.2011] [Citation(s) in RCA: 51] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022] Open
Abstract
Restoration of the epithelial barrier following acute lung injury is critical for recovery of lung homeostasis. After injury, alveolar type II epithelial (ATII) cells spread and migrate to cover the denuded surface and, eventually, proliferate and differentiate into type I cells. The chemokine CXCL12, also known as stromal cell-derived factor 1α, has well-recognized roles in organogenesis, hematopoiesis, and immune responses through its binding to the chemokine receptor CXCR4. While CXCL12/CXCR4 signaling is known to be important in immune cell migration, the role of this chemokine-receptor interaction has not been studied in alveolar epithelial repair mechanisms. In this study, we demonstrated that secretion of CXCL12 was increased in the bronchoalveolar lavage of rats ventilated with an injurious tidal volume (25 ml/kg). We also found that CXCL12 secretion was increased by primary rat ATII cells and a mouse alveolar epithelial (MLE12) cell line following scratch wounding and that both types of cells express CXCR4. CXCL12 significantly increased ATII cell migration in a scratch-wound assay. When we treated cells with a specific antagonist for CXCR4, AMD-3100, cell migration was significantly inhibited. Knockdown of CXCR4 by short hairpin RNA (shRNA) caused decreased cell migration compared with cells expressing a nonspecific shRNA. Treatment with AMD-3100 decreased matrix metalloproteinase-14 expression, increased tissue inhibitor of metalloproteinase-3 expression, decreased matrix metalloproteinase-2 activity, and prevented CXCL12-induced Rac1 activation. Similar results were obtained with shRNA knockdown of CXCR4. These findings may help identify a therapeutic target for augmenting epithelial repair following acute lung injury.
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Affiliation(s)
- Manik C Ghosh
- Department of Physiology, Univ. of Tennessee Health Science Center, Memphis, TN 38163, USA
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