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Hidden in Plain Sight: The Overlooked Role of Pulmonary Macrophages in the Pathogenesis of Asthma.
Am J Respir Cell Mol Biol. 2016 Oct;55(4):465-466
Authors: Park GY, Christman JW
PMID: 27689794 [PubMed – as supplied by publisher]
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Mesenchymal stem cells induce suppressive macrophages through phagocytosis in a mouse model of asthma.
Stem Cells. 2016 Feb 17;
Authors: Braza F, Dirou S, Forest V, Sauzeau V, Hassoun D, Chesné J, Cheminant-Muller MA, Sagan C, Magnan A, Lemarchand P
Abstract
Mesenchymal stem cell (MSC) immunosuppressive functions make them attractive candidates for anti-inflammatory therapy in allergic asthma. However the mechanisms by which they ensure therapeutic effects remain to be elucidated. In an acute mouse model of house dust mite (Der f)-induced asthma, one i.v. MSC injection was sufficient to normalize and stabilize lung function in Der f-sensitized mice as compared to control mice. MSC injection decreased in vivo airway responsiveness and decreased ex vivo carbachol-induced bronchial contraction, maintaining bronchial expression of the inhibitory type 2 muscarinic receptor. To evaluate in vivo MSC survival, MSCs were labelled with PKH26 fluorescent marker prior to i.v. injection, and 1 to 10 days later total lungs were digested to obtain single-cell suspensions. 91.5?±?2.3% and 86.6?±?6.3% of the recovered PKH26(+) lung cells expressed specific macrophage markers in control and Der f mice respectively, suggesting that macrophages had phagocyted in vivo the injected MSCs. Interestingly, only PKH26(+) macrophages expressed M2 phenotype, while the innate PKH26(-) macrophages expressed M1 phenotype. Finally, the remaining 0.5% PKH26(+) MSCs expressed 10 to 100 fold more COX-2 than before injection, suggesting in vivo MSC phenotype modification. Together, the results of this study indicate that MSCs attenuate asthma by being phagocyted by lung macrophages, which in turn acquire a M2 suppressive phenotype. This article is protected by copyright. All rights reserved.
PMID: 26891455 [PubMed – as supplied by publisher]
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Sonchus asper extract inhibits LPS-induced oxidative stress and pro-inflammatory cytokine production in RAW264.7 macrophages.
Nutr Res Pract. 2015 Dec;9(6):579-585
Authors: Wang L, Xu ML, Liu J, Wang Y, Hu JH, Wang MH
Abstract
BACKGROUND/OBJECTIVES: Sonchus asper is used extensively as an herbal anti-inflammatory for treatment of bronchitis, asthma, wounds, burns, and cough; however, further investigation is needed in order to understand the underlying mechanism. To determine its mechanism of action, we examined the effects of an ethyl acetate fraction (EAF) of S. asper on nitric oxide (NO) production and prostaglandin-E2 levels in lipopolysaccharide (LPS)-stimulated RAW264.7 macrophages.
MATERIALS/METHODS: An in vitro culture of RAW264.7 macrophages was treated with LPS to induce inflammation.
RESULTS: Treatment with EAF resulted in significant suppression of oxidative stress in RAW264.7 macrophages as demonstrated by increased endogenous superoxide dismutase (SOD) activity and intracellular glutathione levels, decreased generation of reactive oxygen species and lipid peroxidation, and restoration of the mitochondrial membrane potential. To confirm its anti-inflammatory effects, analysis of expression of inducible NO synthase, cyclooxygenase-2, tumor necrosis factor-?, and the anti-inflammatory cytokines IL-1? and IL-6 was performed using semi-quantitative RT-PCR. EAF treatment resulted in significantly reduced dose-dependent expression of all of these factors, and enhanced expression of the antioxidants MnSOD and heme oxygenase-1. In addition, HPLC fingerprint results suggest that rutin, caffeic acid, and quercetin may be the active ingredients in EAF.
CONCLUSIONS: Taken together, findings of this study imply that the anti-inflammatory effect of EAF on LPS-stimulated RAW264.7 cells is mediated by suppression of oxidative stress.
PMID: 26634045 [PubMed – as supplied by publisher]
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Docosahexaenoic acid ester of phloridzin inhibit lipopolysaccharide-induced inflammation in THP-1 differentiated macrophages.
Int Immunopharmacol. 2015 Jan 28;
Authors: Sekhon-Loodu S, Ziaullah, Rupasinghe HP
Abstract
Phloridzin or phlorizin (PZ) is a predominant phenolic compound found in apple and also used in various natural health products. Phloridzin shows poor absorption and cellular uptake due to its hydrophilic nature. The aim was to investigate and compare the effect of docosahexaenoic acid (DHA) ester of PZ (PZ-DHA) and its parent compounds (phloridzin and DHA), phloretin (the aglycone of PZ) and cyclooxygenase inhibitory drugs (diclofenac and nimesulide) on production of pro-inflammatory biomarkers in inflammation-induced macrophages by lipopolysaccharide (LPS)-stimulation. Human THP-1 monocytes were seeded in 24-well plates (5×10(5)/well) and treated with phorbol 12-myristate 13-acetate (PMA, 0.1?g/mL) for 48h to induce macrophage differentiation. After 48h, the differentiated macrophages were washed with Hank’s buffer and treated with various concentrations of test compounds for 4h, followed by the LPS-stimulation (18h). Pre-exposure of PZ-DHA ester was more effective in reducing tumor necrosis factor-alpha (TNF-?), interleukin-6 (IL-6) and cyclooxygenase-2 (COX-2) protein levels compared to DHA and nimesulide. However, diclofenac was the most effective in reducing prostaglandin (PGE2) level by depicting a dose-dependent response. However, PZ-DHA ester and DHA were the most effective in inhibiting the activation of nuclear factor-kappa B (NF-?B) among other test compounds. Our results suggest that PZ-DHA ester might possess potential therapeutic activity to treat inflammation related disorders such as type 2 diabetes, asthma, atherosclerosis and inflammatory bowel disease.
PMID: 25637769 [PubMed – as supplied by publisher]
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Alveolar Macrophages Play a Key Role in Cockroach-Induced Allergic Inflammation via TNF-? Pathway.
PLoS One. 2012;7(10):e47971
Authors: Kim JY, Sohn JH, Choi JM, Lee JH, Hong CS, Lee JS, Park JW
Abstract
The activity of the serine protease in the German cockroach allergen is important to the development of allergic disease. The protease-activated receptor (PAR)-2, which is expressed in numerous cell types in lung tissue, is known to mediate the cellular events caused by inhaled serine protease. Alveolar macrophages express PAR-2 and produce considerable amounts of tumor necrosis factor (TNF)-?. We determined whether the serine protease in German cockroach extract (GCE) enhances TNF-? production by alveolar macrophages through the PAR-2 pathway and whether the TNF-? production affects GCE-induced pulmonary inflammation. Effects of GCE on alveolar macrophages and TNF-? production were evaluated using in vitro MH-S and RAW264.6 cells and in vivo GCE-induced asthma models of BALB/c mice. GCE contained a large amount of serine protease. In the MH-S and RAW264.7 cells, GCE activated PAR-2 and thereby produced TNF-?. In the GCE-induced asthma model, intranasal administration of GCE increased airway hyperresponsiveness (AHR), inflammatory cell infiltration, productions of serum immunoglobulin E, interleukin (IL)-5, IL-13 and TNF-? production in alveolar macrophages. Blockade of serine proteases prevented the development of GCE induced allergic pathologies. TNF-? blockade also prevented the development of such asthma-like lesions. Depletion of alveolar macrophages reduced AHR and intracellular TNF-? level in pulmonary cell populations in the GCE-induced asthma model. These results suggest that serine protease from GCE affects asthma through an alveolar macrophage and TNF-? dependent manner, reflecting the close relation of innate and adaptive immune response in allergic asthma model.
PMID: 23094102 [PubMed – in process]
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Alveolar macrophages modulate allergic inflammation in a murine model of asthma.
Exp Mol Med. 2011 Mar 18;
Authors: Bang BR, Chun E, Shim EJ, Lee HS, Lee SY, Cho SH, Min KU, Kim YY, Park HW
The role of alveolar macrophages (AMs) in the pathogenesis of asthma is still unknown. The aim of the present study was to investigate the effects of AM in the murine model of asthma. AMs were selectively depleted by liposomes containing clodronate just before allergen challenges, and changes in inflammatory cells and cytokine concentrations in bronchoalveolar lavage (BAL) fluid were measured. AMs were then adoptively transferred to AM-depleted sensitized mice and changes were measured. Phenotypic changes in AMs were evaluated after in vitro allergen stimulation. AM-depletion after sensitization significantly increased the number of eosinophils and lymphocytes and the concentrations of IL-4, IL-5 and GM-CSF in BAL fluid. These changes were significantly ameliorated only by adoptive transfer of unsensitized AMs, not by sensitized AMs. In addition, in vitro allergen stimulation of AMs resulted in their gaining the ability to produce inflammatory cytokines, such as IL-1b, IL-6 and TNF-?, and losing the ability to suppress GM-CSF concentrations in BAL fluid. These findings suggested that AMs worked probably through GM-CSF-dependent mechanisms, although further confirmatory experiments are needed. Our results indicate that the role of AMs in the context of airway inflammation should be re-examined.
PMID: 21415590 [PubMed – as supplied by publisher]
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Allergen-Induced Coexpression of bFGF and TGF-?1 by Macrophages in a Mouse Model of Airway Remodeling: bFGF Induces Macrophage TGF-?1 Expression in vitro.
Int Arch Allergy Immunol. 2010 Nov 25;155(1):12-22
Authors: Yum HY, Cho JY, Miller M, Broide DH
Background: Basic fibroblast growth factor (bFGF) is a cytokine that is mitogenic for fibroblasts and smooth muscle and may play a role in airway remodeling in asthma. We have used a mouse model of chronic ovalbumin (OVA) allergen-induced airway remodeling to determine whether bFGF and fibroblast growth factor receptor-1 are expressed and regulated by corticosteroids in the airway, as well as to determine whether bFGF mediates expression of another proremodeling cytokine, transforming growth factor (TGF)-?1. Methods: The airway levels and localization of bFGF, FGF receptor-1 and TGF-?1 were determined by ELISA, immunohistology and image analysis in the remodeled airways of chronic OVA-challenged mice treated with either corticosteroids or diluent. In vitro cultures of bone narrow-derived macrophages were used to determine whether bFGF induced TGF-?1 expression. Results: Mice chronically challenged with OVA developed significant airway remodeling that was associated with significantly increased levels of bFGF and TGF-?1. Immunohistochemistry demonstrated significantly increased bFGF and FGF receptor-1 expression by peri- bronchial F4/80+ cells. Double-label immunofluorescence microscopy studies demonstrated that peribronchial macrophages coexpressed bFGF and TGF-?1. In vitro studies demonstrated that incubation of bone marrow-derived macrophages with bFGF induced expression of TGF-?1. Mice treated with corticosteroids and subjected to chronic OVA challenge had significantly reduced levels of bFGF, FGF receptor-1, peribronchial TGF-?1+ cells and airway remodeling. Conclusions: Overall, this study demonstrates that allergen challenge stimulates peribronchial macrophages to coexpress bFGF and TGF-?1 and that bFGF may potentiate macrophage release of TGF-?1 through autocrine and/or paracrine pathways.
PMID: 21109744 [PubMed – as supplied by publisher]
View full post on pubmed: asthma