A2B adenosine receptor dampens hypoxia-induced vascular leak.
ABSTRACT Extracellular adenosine has been implicated in adaptation to hypoxia and previous studies demonstrated a central role in vascular responses. Here, we examined the contribution of individual adenosine receptors (ARs: A1AR/A2AAR/A2BAR/A3AR) to vascular leak induced by hypoxia. Initial profiling studies revealed that siRNA-mediated repression of the A2BAR selectively increased endothelial leak in response to hypoxia in vitro. In parallel, vascular permeability was significantly increased in vascular organs of A2BAR(-/-)-mice subjected to ambient hypoxia (8% oxygen, 4 hours; eg, lung: 2.1 +/- 0.12-fold increase). By contrast, hypoxia-induced vascular leak was not accentuated in A1AR(-/-)-, A2AAR(-/-)-, or A3AR(-/-)-deficient mice, suggesting a degree of specificity for the A2BAR. Further studies in wild type mice revealed that the selective A2BAR antagonist PSB1115 resulted in profound increases in hypoxia-associated vascular leakage while A2BAR agonist (BAY60-6583 [2-[6-amino-3,5-dicyano-4-[4-(cyclopropylmethoxy)-. phenyl]pyridin-2-ylsulfanyl]acetamide]) treatment was associated with almost complete reversal of hypoxia-induced vascular leakage (eg, lung: 2.0 +/- 0.21-fold reduction). Studies in bone marrow chimeric A2BAR mice suggested a predominant role of vascular A2BARs in this response, while hypoxia-associated increases in tissue neutrophils were, at least in part, mediated by A2BAR expressing hematopoietic cells. Taken together, these studies provide pharmacologic and genetic evidence for vascular A2BAR signaling as central control point of hypoxia-associated vascular leak.
- [Show abstract] [Hide abstract]
ABSTRACT: AimTo investigate the behavior of dental pulp cells under hypoxic conditions in vivo using an experimental animal model.MethodologyA mini-screw was inserted into the inferior dental nerve canal of rats to arrest the blood supply, which resulted in a reduced oxygen level in the dental pulps of molar teeth used for the experimental group. The decrease in blood supply was evaluated by injected India ink in transparent specimens. The hypoxia marker Hypoxyprobe-1 was investigated by immunohistochemical staining. The mRNA expressions of ATP-binding cassette transporter (ABC) G2 (ABCG2) which is a markers for the capacity to excrete metabolites and for stem-like cells, as well as Dentine sialophosphoprotein (DSPP) and Osteocalcin (OCN) which are markers for mineralization were evaluated by RT-PCR. Protein was evaluated by immunohistochemical staining using ABCG2, Dentine sialoprotein (DSP) OCN.ResultsThe evaluation of India ink indicated a decreased blood supply in the transparent specimens, and Hypoxyprobe-1 immunohistochemical staining showed positive expression. ABCG2, DSPP and OCN mRNA expression increased at 7 and 14 days. Immunohistochemically, ABCG2, DSP, OCN-positive cells were localized in the odontoblastic layer.Conclusions Hypoxic conditions promoted mineralization and differentiation of dental pulp cells of the odontoblastic layer.This article is protected by copyright. All rights reserved.International Endodontic Journal 03/2014; · 2.05 Impact Factor
- [Show abstract] [Hide abstract]
ABSTRACT: Objectives: Emergence of multidrug resistance among Streptococcus pneumoniae (SP), has limited the available options used to treat infections caused by this organism. The objective of this study was to compare the role of monotherapy and combination therapy with ampicillin (AMP) and azithromycin (AZM) in eradicating bacterial burden and down regulating lung inflammation in a murine experimental pneumococcal infection model. Balb/C mice were infected with 106 CFU of SP. Treatments with intravenous ampicillin (200 mg/kg) and azithromycin (50 mg/kg) either alone or in combination was initiated 18 h post infection, animals were sacrificed from 0 - 6 h after initiation of treatment. AMP and AZM were quantified in serum by microbiological assay. Levels of TNF-alpha, IFN-gamma IL-6, and IL-10 in serum and in lungs, along with myeloperoxidase, inflammatory cell count in broncho alveolar lavage fluid, COX-2 and histopathological changes in lungs were estimated. Combination therapy down regulated lung inflammation and accelerated bacterial clearance. This approach also significantly decreased TNF-alpha, IFN-gamma, IL-6 and increased IL-10 level in serum and lungs along with decreased myeloperoxidase, pulmonary vascular permeability, inflammatory cell numbers and COX-2 levels in lungs. Combinatorial therapy resulted in comparable bactericidal activity against the multi-drug resistant isolate and may represent an alternative dosing strategy, which may help to alleviate problems with pneumococcal pneumonia.Journal of Inflammation 02/2014; 11(1):5. · 2.55 Impact Factor
- 04/2014: pages 83-128;