The Experts below are selected from a list of 321 Experts worldwide ranked by ideXlab platform
Krishnan Raghavendran - One of the best experts on this subject based on the ideXlab platform.
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Molecular Characterization of Hypoxic Alveolar Epithelial Cells After Lung Contusion Indicates an Important Role for HIF-1α.
Annals of surgery, 2018Co-Authors: Matthew A. Sherman, Vladislav A. Dolgachev, Madathilparambil V Suresh, David Machado-aranda, Lane Kelly Mccandless, Xiang Xue, Li Ziru, Yatrik M. Shah, Krishnan RaghavendranAbstract:Objective To understand the fate and regulation of hypoxic type II alveolar epithelial cells (AECs) after Lung Contusion (LC). Background LC due to thoracic trauma is a major risk factor for the development of acute respiratory distress syndrome. AECs have recently been implicated as a primary driver of inflammation in LC. The main pathological consequence of LC is hypoxia, and a key mediator of adaptation to hypoxia is hypoxia-inducible factor (HIF)-1. We have recently published that HIF-1α is a major driver of acute inflammation after LC through type II AEC. Methods LC was induced in wild-type mice (C57BL/6), luciferase-based hypoxia reporter mice (ODD-Luc), and HIF-1α conditional knockout mice. The degree of hypoxia was assessed using hypoxyprobe and in vivo imaging system. The fate of hypoxic AEC was evaluated by luciferase dual staining with caspases-3 and Ki-67, terminal deoxynucleotidyl transferase dUTP nick end labeling, and flow cytometry with ApoStat. NLRP-3 expression was determined by western blot. Laser capture microdissection was used to isolate AECs in vivo, and collected RNA was analyzed by Q-PCR for HIF-related pathways. Results Global hypoxia was present after LC, but hypoxic foci were not uniform. Hypoxic AECs preferentially undergo apoptosis. There were significant reductions in NLRP-3 in HIF-1α conditional knockout mice. The expression of proteins involved in HIF-related pathways and inflammasome activation were significantly increased in hypoxic AECs. Conclusions These are the first in vivo data to identify, isolate, and characterize hypoxic AECs. HIF-1α regulation through hypoxic AECs is critical to the initiation of acute inflammation after LC.
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Toll-Like Receptor-9 (TLR9) is Requisite for Acute Inflammatory Response and Injury Following Lung Contusion.
Shock (Augusta Ga.), 2016Co-Authors: Madathilparambil V Suresh, Vladislav A. Dolgachev, Bivin Thomas, David Machado-aranda, Matthew A. Sherman, Rebecca Goldberg, Mark W. Johnson, Aulina Chowdhury, Krishnan RaghavendranAbstract:Lung Contusion (LC) is a significant risk factor for the development of acute respiratory distress syndrome. Toll-like receptor 9 (TLR9) recognizes specific unmethylated CpG motifs, which are prevalent in microbial but not vertebrate genomic DNA, leading to innate and acquired immune responses. TLR9 signaling has recently been implicated as a critical component of the inflammatory response following Lung injury. The aim of the present study was to evaluate the contribution of TLR9 signaling to the acute physiologic changes following LC. Nonlethal unilateral closed-chest LC was induced in TLR9 (-/-) and wild-type (WT) mice. The mice were sacrificed at 5, 24, 48, and 72-h time points. The extent of injury was assessed by measuring bronchoalveolar lavage, cells (cytospin), albumin (permeability injury), and cytokines (inflammation). Following LC, only the TLR9 (-/-) mice showed significant reductions in the levels of albumin; release of pro-inflammatory cytokines IL-1β, IL-6, and Keratinocyte chemoattractant; production of macrophage chemoattractant protein 5; and recruitment of alveolar macrophages and neutrophil infiltration. Histological evaluation demonstrated significantly worse injury at all-time points for WT mice. Macrophages, isolated from TLR9 (-/-) mice, exhibited increased phagocytic activity at 24 h after LC compared with those isolated from WT mice. TLR9, therefore, appears to be functionally important in the development of progressive Lung injury and inflammation following LC. Our findings provide a new framework for understanding the pathogenesis of Lung injury and suggest blockade of TLR9 as a new therapeutic strategy for the treatment of LC-induced Lung injury.
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activation of hypoxia inducible factor 1α in type 2 alveolar epithelial cell is a major driver of acute inflammation following Lung Contusion
Critical Care Medicine, 2014Co-Authors: Madathilparambil V Suresh, Sadeesh K Ramakrishnan, Bivin Thomas, David Machadoaranda, Yu Bi, Nicholas Talarico, Erik R Anderson, Shah M Yatrik, Krishnan RaghavendranAbstract:Objective Lung Contusion is a major risk factor for the development of acute respiratory distress syndrome. Hypoxia-inducible factor-1α is the primary transcription factor that is responsible for regulating the cellular response to changes in oxygen tension. We set to determine if hypoxia-inducible factor-1α plays a role in the pathogenesis of acute inflammatory response and injury in Lung Contusion.
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Electroporation-Mediated Delivery of Genes in Rodent Models of Lung Contusion
Methods in molecular biology (Clifton N.J.), 2014Co-Authors: David Machado-aranda, Krishnan RaghavendranAbstract:Several of the biological processes involved in the pathogenesis of acute Lung injury and acute respiratory distress syndrome after Lung Contusion are regulated at a genetic and epigenetic level. Thus, strategies to manipulate gene expression in this context are highly desirable not only to elucidate the mechanisms involved but also to look for potential therapies. In the present chapter, we describe mouse and rat models of inducing blunt thoracic injury followed by electroporation-mediated gene delivery to the Lung. Electroporation is a highly efficient and easily reproducible technique that allows circumvention of several of Lung gene delivery challenges and safety issues present with other forms of Lung gene therapy.
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Interleukin 10 overexpression alters survival in the setting of gram-negative pneumonia following Lung Contusion.
Shock (Augusta Ga.), 2014Co-Authors: Vladislav A. Dolgachev, Krishnan Raghavendran, Lei Sun, Thomas P. Shanley, Mark R. HemmilaAbstract:Objective Lung Contusion injury produces a vulnerable window within the inflammatory defenses of the Lung that predisposes the patient to pneumonia. IL-10 is a known anti-inflammatory mediator produced by macrophages and capable of down-regulating acute Lung inflammation. We investigated the impact of increased levels of IL-10 within the Lung on survival and the host response to trauma in the setting of Lung Contusion and Gram-negative pneumonia.
Paul R Knight - One of the best experts on this subject based on the ideXlab platform.
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role of pulmonary artery reactivity and nitric oxide in injury and inflammation following Lung Contusion
Shock, 2013Co-Authors: Satyan Lakshminrusimha, Bruce A Davidson, Jadwiga D Helinski, Paul R Knight, Madathilparambil V Suresh, Sylvia F Gugino, Lori Nielsen, James A Russell, Bi Yu, Lixia ZengAbstract:Rationale The mechanisms contributing to hypoxia in Lung Contusion remain unclear and not temporally associated with the peak onset of acute inflammation.
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Role of macrophage chemoattractant protein-1 in acute inflammation after Lung Contusion.
American journal of respiratory cell and molecular biology, 2012Co-Authors: Madathilparambil V Suresh, Bruce A Davidson, Jadwiga D Helinski, Paul R Knight, David Machado-aranda, Matthew D. Bender, Laura Ochoa-frongia, Cory M. Hogaboam, Bethany B. MooreAbstract:Lung Contusion (LC), commonly observed in patients with thoracic trauma is a leading risk factor for development of acute Lung injury/acute respiratory distress syndrome. Previously, we have shown that CC chemokine ligand (CCL)-2, a monotactic chemokine abundant in the Lungs, is significantly elevated in LC. This study investigated the nature of protection afforded by CCL-2 in acute Lung injury/acute respiratory distress syndrome during LC, using rats and CC chemokine receptor (CCR) 2 knockout (CCR2(-/-)) mice. Rats injected with a polyclonal antibody to CCL-2 showed higher levels of albumin and IL-6 in the bronchoalveolar lavage and myeloperoxidase in the Lung tissue after LC. Closed-chest bilateral LC demonstrated CCL-2 localization in alveolar macrophages (AMs) and epithelial cells. Subsequent experiments performed using a murine model of LC showed that the extent of injury, assessed by pulmonary compliance and albumin levels in the bronchoalveolar lavage, was higher in the CCR2(-/-) mice when compared with the wild-type (WT) mice. We also found increased release of IL-1β, IL-6, macrophage inflammatory protein-1, and keratinocyte chemoattractant, lower recruitment of AMs, and higher neutrophil infiltration and phagocytic activity in CCR2(-/-) mice at 24 hours. However, impaired phagocytic activity was observed at 48 hours compared with the WT. Production of CCL-2 and macrophage chemoattractant protein-5 was increased in the absence of CCR2, thus suggesting a negative feedback mechanism of regulation. Isolated AMs in the CCR2(-/-) mice showed a predominant M1 phenotype compared with the predominant M2 phenotype in WT mice. Taken together, the above results show that CCL-2 is functionally important in the down-modulation of injury and inflammation in LC.
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Lung Contusion: inflammatory mechanisms and interaction with other injuries.
Shock (Augusta Ga.), 2009Co-Authors: Krishnan Raghavendran, Bruce A Davidson, Jadwiga D Helinski, Robert H Notter, Steven L. Kunkel, Paul R KnightAbstract:This article reviews current animal models and laboratory studies investigating the pathophysiology of Lung Contusion (LC), a common and severe condition in patients with blunt thoracic trauma. Emphasis is on studies elucidating cells, mediators, receptors, and processes important in the innate pulmonary inflammatory response that contribute to LC injury. Surfactant dysfunction in the pathogenesis of LC is also discussed, as is the potential role of epithelial cell or neutrophil apoptosis. Studies examining combination injuries where LC is exacerbated by secondary insults such as gastric aspiration in trauma patients are also noted. The need for continuing mechanism-based research to further clarify the pathophysiology of LC injury, and to define and test potential therapeutic interventions targeting specific aspects of inflammation or surfactant dysfunction to improve clinical outcomes in patients with LC, is also emphasized.
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Predictive modeling and inflammatory biomarkers in rats with Lung Contusion and gastric aspiration
The Journal of trauma, 2009Co-Authors: Krishnan Raghavendran, Bruce A Davidson, Jadwiga D Helinski, Robert H Notter, Alan D. Hutson, Scott R. Nodzo, Paul R KnightAbstract:This study uses statistical predictive modeling and hierarchical cluster analyses to examine inflammatory mediators and cells in bronchoalveolar lavage (BAL) as putative biomarkers in rats with blunt trauma Lung Contusion (LC), gastric aspiration (combined acid and small gastric food particles, CASP), or a combination of the two. Specific parameters assessed in the innate pulmonary inflammatory response were leukocytes, macrophages and polymorphonuclear neutrophils (PMNs) in BAL, whole Lung myeloperoxidase (MPO) activity, and a series of cytokines/chemokines present in BAL at 5 or 24 hr post-injury: tumor necrosis factor-α (TNFα), interleukin (IL)-1β, IL-6, interferon-γ (IFN-γ), IL-10, macrophage inflammatory protein-2 (MIP-2), cytokine-induced neutrophil chemoattractant-1 (CINC-1), and monocyte chemoattractant protein-1 (MCP-1). Rats with LC, CASP, LC+CASP all had severe Lung injury compared to uninjured controls based on decreased arterial oxygenation and/or increased BAL albumin at 5 or 24 hr post-insult. However, the injury groups had distinct overall patterns of inflammation that allowed them to be discriminated accurately by hierarchical cluster analysis (29/30 and 35/37 rats were correctly classified in hierarchical clusters at 5 and 24 hr, respectively). Moreover, predictive analyses based on an extension of standard receiver operator characteristic (ROC) methodology discriminated individual animals and groups with similar high accuracy based on a maximum of two inflammatory parameters per group (29/30 and 36/37 rats were correctly classified at 5 hr and 24 hr, respectively). These results support the possibility that inflammatory biomarker profiles could be developed in the future to improve the diagnosis and management of trauma patients with unwitnessed (occult) gastric aspiration who have an increased risk of clinical acute Lung injury (ALI) or the acute respiratory distress syndrome (ARDS).
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Superimposed Gastric Aspiration Increases the Severity of Inflammation and Permeability Injury in a Rat Model of Lung Contusion
The Journal of surgical research, 2008Co-Authors: Krishnan Raghavendran, Bruce A Davidson, Jadwiga D Helinski, Robert H Notter, Alan D. Hutson, John C. Huebschmann, Merrily T. Dayton, Paul R KnightAbstract:Introduction Lung Contusion (LC) from blunt thoracic trauma is a clinically-prevalent condition that can progress to acute Lung injury (ALI) and acute respiratory distress syndrome (ARDS). Patients with LC are at risk for gastric aspiration at the time of trauma, but the combined insults have not been well-studied in animal models. This study tests the hypothesis that concurrent gastric aspiration (combined acid and small gastric particles, CASP) at the time of trauma significantly increases permeability injury and inflammation compared with LC alone, and also modifies the inflammatory response to include distinct features compared with the aspiration component of injury. Materials and Methods Four groups of adult male Long-Evans rats were studied (LC, CASP, LC + CASP, uninjured controls). LC was induced in anesthetized rats at a fixed impact energy of 2.0 J, and CASP (1.2 mL/kg body weight, 40 mg particles/mL, pH = 1.25) was instilled through an endotracheal tube. Lung injury and inflammation were assessed by arterial blood gases and levels of albumin, cells, and cytokines/chemokines in bronchoalveolar lavage (BAL) at 5 and 24 h. Results Rats with LC + CASP had lower mean PaO2/FiO2 ratios compared with LC alone at 24 h, and higher BAL albumin concentrations compared with either LC or CASP alone. Rats with LC + CASP versus LC had more severe inflammation based on higher levels of PMN in BAL at 5 h, increased whole Lung myeloperoxidase (MPO) activity at 5 and 24 h, and increased levels of inflammatory mediators in BAL (TNFα, IL-1β, and MCP-1 at 5 and 24 h; IL-10, MIP-2, and CINC-1 at 5 h). Rats with LC + CASP also had distinct aspects of inflammation compared with CASP alone, i.e., significantly higher levels of IL-10 (5 and 24 h), IL-1β (24 h), CINC-1 (24 h), and MCP-1 (24 h), and significantly lower levels of MPO (5 h), MIP-2 (5 h), and CINC-1 (5 h). Conclusions Concurrent gastric aspiration can exacerbate permeability Lung injury and inflammation associated with LC, and also generates a modified inflammatory response compared with aspiration alone. Unwitnessed gastric aspiration has the potential to contribute to more severe forms of LC injury associated with progression to ALI/ARDS and pneumonia in patients with thoracic trauma.
Bruce A Davidson - One of the best experts on this subject based on the ideXlab platform.
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role of pulmonary artery reactivity and nitric oxide in injury and inflammation following Lung Contusion
Shock, 2013Co-Authors: Satyan Lakshminrusimha, Bruce A Davidson, Jadwiga D Helinski, Paul R Knight, Madathilparambil V Suresh, Sylvia F Gugino, Lori Nielsen, James A Russell, Bi Yu, Lixia ZengAbstract:Rationale The mechanisms contributing to hypoxia in Lung Contusion remain unclear and not temporally associated with the peak onset of acute inflammation.
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The protective role of MnTBAP in oxidant-mediated injury and inflammation in a rat model of Lung Contusion.
Surgery, 2013Co-Authors: Madathilparambil V Suresh, Bruce A Davidson, Satyan Lakshminrusimha, Lixia Zeng, Nicholas Talarico, David Machado-aranda, Subramaniam Pennathur, Krishnan RaghavendranAbstract:Background Lung Contusion (LC) is a unique direct and focal insult that is considered a major risk factor for the initiation of acute Lung injury and acute respiratory distress syndrome. We have shown recently that consumption of nitric oxide (due to excess superoxide) resulting in peroxynitrite formation leads to decreased vascular reactivity after LC. In this study, we set out to determine whether the superoxide scavenger Mn (III) tetrakis (4-benzoic acid) porphyrin chloride (MnTBAP) plays a protective role in alleviating acute inflammatory response and injury in LC. Methods Nonlethal, closed-chest, bilateral LC was induced in a rodent model. Administration of the superoxide dismutase mimetic MnTBAP concurrently in LC in rats was performed, and bronchoalveolar lavage (BAL) and Lung samples were analyzed for degree of injury and inflammation at 5 and 24 h after the insult. The extent of injury was assessed by the measurement of cells and albumin with cytokine levels in the BAL and Lungs. Lung samples were subjected to H&E and superoxide staining with dihydro-ethidium. Protein-bound dityrosine and nitrotyrosine levels were quantified in Lung tissue by tandem mass spectrometry. Results The degrees of Lung injury after LC as determined by BAL albumin levels were significantly decreased in the MnTBAP-administered rats at all the time points when compared to the corresponding controls. The release of proinflammatory cytokines and BAL neutrophils was significantly less in the rats administered MnTBAP after LC. Administration of MnTBAP decreased tissue damage and decreased necrosis and neutrophil-rich exudate at the 24-h time point. Staining for superoxide anions showed significantly greater intensity in the Lung samples from the LC group compared to the LC+ MnTBAP group. High-performance liquid chromatography/tandem mass spectrometry revealed that MnTBAP treatment significantly attenuated dityrosine and nitrotyrosine levels, consistent with decreased oxidant injury. Conclusion Superoxide dismutase mimetic-MnTBAP reduced permeability and oxidative injury in LC and may have a therapeutic role in diminishing inflammation in LC.
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Role of macrophage chemoattractant protein-1 in acute inflammation after Lung Contusion.
American journal of respiratory cell and molecular biology, 2012Co-Authors: Madathilparambil V Suresh, Bruce A Davidson, Jadwiga D Helinski, Paul R Knight, David Machado-aranda, Matthew D. Bender, Laura Ochoa-frongia, Cory M. Hogaboam, Bethany B. MooreAbstract:Lung Contusion (LC), commonly observed in patients with thoracic trauma is a leading risk factor for development of acute Lung injury/acute respiratory distress syndrome. Previously, we have shown that CC chemokine ligand (CCL)-2, a monotactic chemokine abundant in the Lungs, is significantly elevated in LC. This study investigated the nature of protection afforded by CCL-2 in acute Lung injury/acute respiratory distress syndrome during LC, using rats and CC chemokine receptor (CCR) 2 knockout (CCR2(-/-)) mice. Rats injected with a polyclonal antibody to CCL-2 showed higher levels of albumin and IL-6 in the bronchoalveolar lavage and myeloperoxidase in the Lung tissue after LC. Closed-chest bilateral LC demonstrated CCL-2 localization in alveolar macrophages (AMs) and epithelial cells. Subsequent experiments performed using a murine model of LC showed that the extent of injury, assessed by pulmonary compliance and albumin levels in the bronchoalveolar lavage, was higher in the CCR2(-/-) mice when compared with the wild-type (WT) mice. We also found increased release of IL-1β, IL-6, macrophage inflammatory protein-1, and keratinocyte chemoattractant, lower recruitment of AMs, and higher neutrophil infiltration and phagocytic activity in CCR2(-/-) mice at 24 hours. However, impaired phagocytic activity was observed at 48 hours compared with the WT. Production of CCL-2 and macrophage chemoattractant protein-5 was increased in the absence of CCR2, thus suggesting a negative feedback mechanism of regulation. Isolated AMs in the CCR2(-/-) mice showed a predominant M1 phenotype compared with the predominant M2 phenotype in WT mice. Taken together, the above results show that CCL-2 is functionally important in the down-modulation of injury and inflammation in LC.
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Lung Contusion: inflammatory mechanisms and interaction with other injuries.
Shock (Augusta Ga.), 2009Co-Authors: Krishnan Raghavendran, Bruce A Davidson, Jadwiga D Helinski, Robert H Notter, Steven L. Kunkel, Paul R KnightAbstract:This article reviews current animal models and laboratory studies investigating the pathophysiology of Lung Contusion (LC), a common and severe condition in patients with blunt thoracic trauma. Emphasis is on studies elucidating cells, mediators, receptors, and processes important in the innate pulmonary inflammatory response that contribute to LC injury. Surfactant dysfunction in the pathogenesis of LC is also discussed, as is the potential role of epithelial cell or neutrophil apoptosis. Studies examining combination injuries where LC is exacerbated by secondary insults such as gastric aspiration in trauma patients are also noted. The need for continuing mechanism-based research to further clarify the pathophysiology of LC injury, and to define and test potential therapeutic interventions targeting specific aspects of inflammation or surfactant dysfunction to improve clinical outcomes in patients with LC, is also emphasized.
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Predictive modeling and inflammatory biomarkers in rats with Lung Contusion and gastric aspiration
The Journal of trauma, 2009Co-Authors: Krishnan Raghavendran, Bruce A Davidson, Jadwiga D Helinski, Robert H Notter, Alan D. Hutson, Scott R. Nodzo, Paul R KnightAbstract:This study uses statistical predictive modeling and hierarchical cluster analyses to examine inflammatory mediators and cells in bronchoalveolar lavage (BAL) as putative biomarkers in rats with blunt trauma Lung Contusion (LC), gastric aspiration (combined acid and small gastric food particles, CASP), or a combination of the two. Specific parameters assessed in the innate pulmonary inflammatory response were leukocytes, macrophages and polymorphonuclear neutrophils (PMNs) in BAL, whole Lung myeloperoxidase (MPO) activity, and a series of cytokines/chemokines present in BAL at 5 or 24 hr post-injury: tumor necrosis factor-α (TNFα), interleukin (IL)-1β, IL-6, interferon-γ (IFN-γ), IL-10, macrophage inflammatory protein-2 (MIP-2), cytokine-induced neutrophil chemoattractant-1 (CINC-1), and monocyte chemoattractant protein-1 (MCP-1). Rats with LC, CASP, LC+CASP all had severe Lung injury compared to uninjured controls based on decreased arterial oxygenation and/or increased BAL albumin at 5 or 24 hr post-insult. However, the injury groups had distinct overall patterns of inflammation that allowed them to be discriminated accurately by hierarchical cluster analysis (29/30 and 35/37 rats were correctly classified in hierarchical clusters at 5 and 24 hr, respectively). Moreover, predictive analyses based on an extension of standard receiver operator characteristic (ROC) methodology discriminated individual animals and groups with similar high accuracy based on a maximum of two inflammatory parameters per group (29/30 and 36/37 rats were correctly classified at 5 hr and 24 hr, respectively). These results support the possibility that inflammatory biomarker profiles could be developed in the future to improve the diagnosis and management of trauma patients with unwitnessed (occult) gastric aspiration who have an increased risk of clinical acute Lung injury (ALI) or the acute respiratory distress syndrome (ARDS).
Jadwiga D Helinski - One of the best experts on this subject based on the ideXlab platform.
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role of pulmonary artery reactivity and nitric oxide in injury and inflammation following Lung Contusion
Shock, 2013Co-Authors: Satyan Lakshminrusimha, Bruce A Davidson, Jadwiga D Helinski, Paul R Knight, Madathilparambil V Suresh, Sylvia F Gugino, Lori Nielsen, James A Russell, Bi Yu, Lixia ZengAbstract:Rationale The mechanisms contributing to hypoxia in Lung Contusion remain unclear and not temporally associated with the peak onset of acute inflammation.
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Role of macrophage chemoattractant protein-1 in acute inflammation after Lung Contusion.
American journal of respiratory cell and molecular biology, 2012Co-Authors: Madathilparambil V Suresh, Bruce A Davidson, Jadwiga D Helinski, Paul R Knight, David Machado-aranda, Matthew D. Bender, Laura Ochoa-frongia, Cory M. Hogaboam, Bethany B. MooreAbstract:Lung Contusion (LC), commonly observed in patients with thoracic trauma is a leading risk factor for development of acute Lung injury/acute respiratory distress syndrome. Previously, we have shown that CC chemokine ligand (CCL)-2, a monotactic chemokine abundant in the Lungs, is significantly elevated in LC. This study investigated the nature of protection afforded by CCL-2 in acute Lung injury/acute respiratory distress syndrome during LC, using rats and CC chemokine receptor (CCR) 2 knockout (CCR2(-/-)) mice. Rats injected with a polyclonal antibody to CCL-2 showed higher levels of albumin and IL-6 in the bronchoalveolar lavage and myeloperoxidase in the Lung tissue after LC. Closed-chest bilateral LC demonstrated CCL-2 localization in alveolar macrophages (AMs) and epithelial cells. Subsequent experiments performed using a murine model of LC showed that the extent of injury, assessed by pulmonary compliance and albumin levels in the bronchoalveolar lavage, was higher in the CCR2(-/-) mice when compared with the wild-type (WT) mice. We also found increased release of IL-1β, IL-6, macrophage inflammatory protein-1, and keratinocyte chemoattractant, lower recruitment of AMs, and higher neutrophil infiltration and phagocytic activity in CCR2(-/-) mice at 24 hours. However, impaired phagocytic activity was observed at 48 hours compared with the WT. Production of CCL-2 and macrophage chemoattractant protein-5 was increased in the absence of CCR2, thus suggesting a negative feedback mechanism of regulation. Isolated AMs in the CCR2(-/-) mice showed a predominant M1 phenotype compared with the predominant M2 phenotype in WT mice. Taken together, the above results show that CCL-2 is functionally important in the down-modulation of injury and inflammation in LC.
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Lung Contusion: inflammatory mechanisms and interaction with other injuries.
Shock (Augusta Ga.), 2009Co-Authors: Krishnan Raghavendran, Bruce A Davidson, Jadwiga D Helinski, Robert H Notter, Steven L. Kunkel, Paul R KnightAbstract:This article reviews current animal models and laboratory studies investigating the pathophysiology of Lung Contusion (LC), a common and severe condition in patients with blunt thoracic trauma. Emphasis is on studies elucidating cells, mediators, receptors, and processes important in the innate pulmonary inflammatory response that contribute to LC injury. Surfactant dysfunction in the pathogenesis of LC is also discussed, as is the potential role of epithelial cell or neutrophil apoptosis. Studies examining combination injuries where LC is exacerbated by secondary insults such as gastric aspiration in trauma patients are also noted. The need for continuing mechanism-based research to further clarify the pathophysiology of LC injury, and to define and test potential therapeutic interventions targeting specific aspects of inflammation or surfactant dysfunction to improve clinical outcomes in patients with LC, is also emphasized.
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Predictive modeling and inflammatory biomarkers in rats with Lung Contusion and gastric aspiration
The Journal of trauma, 2009Co-Authors: Krishnan Raghavendran, Bruce A Davidson, Jadwiga D Helinski, Robert H Notter, Alan D. Hutson, Scott R. Nodzo, Paul R KnightAbstract:This study uses statistical predictive modeling and hierarchical cluster analyses to examine inflammatory mediators and cells in bronchoalveolar lavage (BAL) as putative biomarkers in rats with blunt trauma Lung Contusion (LC), gastric aspiration (combined acid and small gastric food particles, CASP), or a combination of the two. Specific parameters assessed in the innate pulmonary inflammatory response were leukocytes, macrophages and polymorphonuclear neutrophils (PMNs) in BAL, whole Lung myeloperoxidase (MPO) activity, and a series of cytokines/chemokines present in BAL at 5 or 24 hr post-injury: tumor necrosis factor-α (TNFα), interleukin (IL)-1β, IL-6, interferon-γ (IFN-γ), IL-10, macrophage inflammatory protein-2 (MIP-2), cytokine-induced neutrophil chemoattractant-1 (CINC-1), and monocyte chemoattractant protein-1 (MCP-1). Rats with LC, CASP, LC+CASP all had severe Lung injury compared to uninjured controls based on decreased arterial oxygenation and/or increased BAL albumin at 5 or 24 hr post-insult. However, the injury groups had distinct overall patterns of inflammation that allowed them to be discriminated accurately by hierarchical cluster analysis (29/30 and 35/37 rats were correctly classified in hierarchical clusters at 5 and 24 hr, respectively). Moreover, predictive analyses based on an extension of standard receiver operator characteristic (ROC) methodology discriminated individual animals and groups with similar high accuracy based on a maximum of two inflammatory parameters per group (29/30 and 36/37 rats were correctly classified at 5 hr and 24 hr, respectively). These results support the possibility that inflammatory biomarker profiles could be developed in the future to improve the diagnosis and management of trauma patients with unwitnessed (occult) gastric aspiration who have an increased risk of clinical acute Lung injury (ALI) or the acute respiratory distress syndrome (ARDS).
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Superimposed Gastric Aspiration Increases the Severity of Inflammation and Permeability Injury in a Rat Model of Lung Contusion
The Journal of surgical research, 2008Co-Authors: Krishnan Raghavendran, Bruce A Davidson, Jadwiga D Helinski, Robert H Notter, Alan D. Hutson, John C. Huebschmann, Merrily T. Dayton, Paul R KnightAbstract:Introduction Lung Contusion (LC) from blunt thoracic trauma is a clinically-prevalent condition that can progress to acute Lung injury (ALI) and acute respiratory distress syndrome (ARDS). Patients with LC are at risk for gastric aspiration at the time of trauma, but the combined insults have not been well-studied in animal models. This study tests the hypothesis that concurrent gastric aspiration (combined acid and small gastric particles, CASP) at the time of trauma significantly increases permeability injury and inflammation compared with LC alone, and also modifies the inflammatory response to include distinct features compared with the aspiration component of injury. Materials and Methods Four groups of adult male Long-Evans rats were studied (LC, CASP, LC + CASP, uninjured controls). LC was induced in anesthetized rats at a fixed impact energy of 2.0 J, and CASP (1.2 mL/kg body weight, 40 mg particles/mL, pH = 1.25) was instilled through an endotracheal tube. Lung injury and inflammation were assessed by arterial blood gases and levels of albumin, cells, and cytokines/chemokines in bronchoalveolar lavage (BAL) at 5 and 24 h. Results Rats with LC + CASP had lower mean PaO2/FiO2 ratios compared with LC alone at 24 h, and higher BAL albumin concentrations compared with either LC or CASP alone. Rats with LC + CASP versus LC had more severe inflammation based on higher levels of PMN in BAL at 5 h, increased whole Lung myeloperoxidase (MPO) activity at 5 and 24 h, and increased levels of inflammatory mediators in BAL (TNFα, IL-1β, and MCP-1 at 5 and 24 h; IL-10, MIP-2, and CINC-1 at 5 h). Rats with LC + CASP also had distinct aspects of inflammation compared with CASP alone, i.e., significantly higher levels of IL-10 (5 and 24 h), IL-1β (24 h), CINC-1 (24 h), and MCP-1 (24 h), and significantly lower levels of MPO (5 h), MIP-2 (5 h), and CINC-1 (5 h). Conclusions Concurrent gastric aspiration can exacerbate permeability Lung injury and inflammation associated with LC, and also generates a modified inflammatory response compared with aspiration alone. Unwitnessed gastric aspiration has the potential to contribute to more severe forms of LC injury associated with progression to ALI/ARDS and pneumonia in patients with thoracic trauma.
David Machado-aranda - One of the best experts on this subject based on the ideXlab platform.
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Molecular Characterization of Hypoxic Alveolar Epithelial Cells After Lung Contusion Indicates an Important Role for HIF-1α.
Annals of surgery, 2018Co-Authors: Matthew A. Sherman, Vladislav A. Dolgachev, Madathilparambil V Suresh, David Machado-aranda, Lane Kelly Mccandless, Xiang Xue, Li Ziru, Yatrik M. Shah, Krishnan RaghavendranAbstract:Objective To understand the fate and regulation of hypoxic type II alveolar epithelial cells (AECs) after Lung Contusion (LC). Background LC due to thoracic trauma is a major risk factor for the development of acute respiratory distress syndrome. AECs have recently been implicated as a primary driver of inflammation in LC. The main pathological consequence of LC is hypoxia, and a key mediator of adaptation to hypoxia is hypoxia-inducible factor (HIF)-1. We have recently published that HIF-1α is a major driver of acute inflammation after LC through type II AEC. Methods LC was induced in wild-type mice (C57BL/6), luciferase-based hypoxia reporter mice (ODD-Luc), and HIF-1α conditional knockout mice. The degree of hypoxia was assessed using hypoxyprobe and in vivo imaging system. The fate of hypoxic AEC was evaluated by luciferase dual staining with caspases-3 and Ki-67, terminal deoxynucleotidyl transferase dUTP nick end labeling, and flow cytometry with ApoStat. NLRP-3 expression was determined by western blot. Laser capture microdissection was used to isolate AECs in vivo, and collected RNA was analyzed by Q-PCR for HIF-related pathways. Results Global hypoxia was present after LC, but hypoxic foci were not uniform. Hypoxic AECs preferentially undergo apoptosis. There were significant reductions in NLRP-3 in HIF-1α conditional knockout mice. The expression of proteins involved in HIF-related pathways and inflammasome activation were significantly increased in hypoxic AECs. Conclusions These are the first in vivo data to identify, isolate, and characterize hypoxic AECs. HIF-1α regulation through hypoxic AECs is critical to the initiation of acute inflammation after LC.
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Toll-Like Receptor-9 (TLR9) is Requisite for Acute Inflammatory Response and Injury Following Lung Contusion.
Shock (Augusta Ga.), 2016Co-Authors: Madathilparambil V Suresh, Vladislav A. Dolgachev, Bivin Thomas, David Machado-aranda, Matthew A. Sherman, Rebecca Goldberg, Mark W. Johnson, Aulina Chowdhury, Krishnan RaghavendranAbstract:Lung Contusion (LC) is a significant risk factor for the development of acute respiratory distress syndrome. Toll-like receptor 9 (TLR9) recognizes specific unmethylated CpG motifs, which are prevalent in microbial but not vertebrate genomic DNA, leading to innate and acquired immune responses. TLR9 signaling has recently been implicated as a critical component of the inflammatory response following Lung injury. The aim of the present study was to evaluate the contribution of TLR9 signaling to the acute physiologic changes following LC. Nonlethal unilateral closed-chest LC was induced in TLR9 (-/-) and wild-type (WT) mice. The mice were sacrificed at 5, 24, 48, and 72-h time points. The extent of injury was assessed by measuring bronchoalveolar lavage, cells (cytospin), albumin (permeability injury), and cytokines (inflammation). Following LC, only the TLR9 (-/-) mice showed significant reductions in the levels of albumin; release of pro-inflammatory cytokines IL-1β, IL-6, and Keratinocyte chemoattractant; production of macrophage chemoattractant protein 5; and recruitment of alveolar macrophages and neutrophil infiltration. Histological evaluation demonstrated significantly worse injury at all-time points for WT mice. Macrophages, isolated from TLR9 (-/-) mice, exhibited increased phagocytic activity at 24 h after LC compared with those isolated from WT mice. TLR9, therefore, appears to be functionally important in the development of progressive Lung injury and inflammation following LC. Our findings provide a new framework for understanding the pathogenesis of Lung injury and suggest blockade of TLR9 as a new therapeutic strategy for the treatment of LC-induced Lung injury.
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Electroporation-Mediated Delivery of Genes in Rodent Models of Lung Contusion
Methods in molecular biology (Clifton N.J.), 2014Co-Authors: David Machado-aranda, Krishnan RaghavendranAbstract:Several of the biological processes involved in the pathogenesis of acute Lung injury and acute respiratory distress syndrome after Lung Contusion are regulated at a genetic and epigenetic level. Thus, strategies to manipulate gene expression in this context are highly desirable not only to elucidate the mechanisms involved but also to look for potential therapies. In the present chapter, we describe mouse and rat models of inducing blunt thoracic injury followed by electroporation-mediated gene delivery to the Lung. Electroporation is a highly efficient and easily reproducible technique that allows circumvention of several of Lung gene delivery challenges and safety issues present with other forms of Lung gene therapy.
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Alveolar macrophage depletion increases the severity of acute inflammation following nonlethal unilateral Lung Contusion in mice.
The journal of trauma and acute care surgery, 2014Co-Authors: David Machado-aranda, Madathilparambil V Suresh, Mark R. Hemmila, Vladislov A. Dolgachev, Krishnan RaghavendranAbstract:Blunt thoracic trauma resulting in Lung Contusion (LC) is an important independent risk factor for the development of pneumonia, acute Lung injury, and its more severe form known as adult respiratory distress syndrome. LC producing one of these respiratory complications results in mortality rates between 10% and 25% among adult trauma patients.1–3 Both macrophages and neutrophils are consistently recovered in bronchial alveolar lavage (BAL) fluid from patients with LC injury. While the importance of the neutrophils in the Lung inflammatory response has been extensively studied, the role of alveolar macrophages (AMs) is a subject of debate.4,5 AMs are considered part of the nonspecific host immune system and have two main activation phenotypes as follows: M1 or classical phenotype mediates host defenses against bacteria, viruses, and protozoa. They are characterized by secreting a significant number of proinflammatory cytokines and have increased nitric oxide synthase activity resulting in the production of nitric oxide used for bacterial killing. Conversely, the M2 phenotype, also known as an alternative pathway, participates in helminth infections and probably has an important anti-inflammatory activity via interleukin 10 (IL-10) signaling. However, exuberant M2 activation along with their associated cytokine profile (IL-10, transforming growth factor β, and monocyte chemoattractant protein 1 [MCP-1]) has been implicated in persistent bacterial infection and pulmonary fibrosis.6–9 Previous experiments from our laboratory have shown that LC in mice significantly reduces the number of AMs present in BAL samples.10 Interestingly, we found that phagocytic capacity of AMs is improved and that polarization moves toward the M2 phenotype. Using CCR-2−/− mice, we found that some of these events are dependent on MCP-1 pathway. Thus, in this present study, to understand the precise role of AMs during LC, we performed experiments using macrophage-depleting agent clodronate before traumatic injury. Importantly, we found an increased severity of Lung inflammation with diminution of AMs after LC injury.
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The protective role of MnTBAP in oxidant-mediated injury and inflammation in a rat model of Lung Contusion.
Surgery, 2013Co-Authors: Madathilparambil V Suresh, Bruce A Davidson, Satyan Lakshminrusimha, Lixia Zeng, Nicholas Talarico, David Machado-aranda, Subramaniam Pennathur, Krishnan RaghavendranAbstract:Background Lung Contusion (LC) is a unique direct and focal insult that is considered a major risk factor for the initiation of acute Lung injury and acute respiratory distress syndrome. We have shown recently that consumption of nitric oxide (due to excess superoxide) resulting in peroxynitrite formation leads to decreased vascular reactivity after LC. In this study, we set out to determine whether the superoxide scavenger Mn (III) tetrakis (4-benzoic acid) porphyrin chloride (MnTBAP) plays a protective role in alleviating acute inflammatory response and injury in LC. Methods Nonlethal, closed-chest, bilateral LC was induced in a rodent model. Administration of the superoxide dismutase mimetic MnTBAP concurrently in LC in rats was performed, and bronchoalveolar lavage (BAL) and Lung samples were analyzed for degree of injury and inflammation at 5 and 24 h after the insult. The extent of injury was assessed by the measurement of cells and albumin with cytokine levels in the BAL and Lungs. Lung samples were subjected to H&E and superoxide staining with dihydro-ethidium. Protein-bound dityrosine and nitrotyrosine levels were quantified in Lung tissue by tandem mass spectrometry. Results The degrees of Lung injury after LC as determined by BAL albumin levels were significantly decreased in the MnTBAP-administered rats at all the time points when compared to the corresponding controls. The release of proinflammatory cytokines and BAL neutrophils was significantly less in the rats administered MnTBAP after LC. Administration of MnTBAP decreased tissue damage and decreased necrosis and neutrophil-rich exudate at the 24-h time point. Staining for superoxide anions showed significantly greater intensity in the Lung samples from the LC group compared to the LC+ MnTBAP group. High-performance liquid chromatography/tandem mass spectrometry revealed that MnTBAP treatment significantly attenuated dityrosine and nitrotyrosine levels, consistent with decreased oxidant injury. Conclusion Superoxide dismutase mimetic-MnTBAP reduced permeability and oxidative injury in LC and may have a therapeutic role in diminishing inflammation in LC.
