David A Fullerton

University of Colorado, Denver, Colorado, United States

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Publications (215)805.43 Total impact

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    ABSTRACT: Paraplegia following complex aortic intervention relies on crude evaluation of lower extremity strength such as whether the patient can lift their legs or flex the ankle. Little attention has been given to the possible long-term neurologic sequelae following these procedures in patients appearing functionally normal. We hypothesize that mice subjected to minimal ischemic time will have functional and histological changes despite the gross appearance of normal function. Male mice underwent 3min of aortic occlusion (n=14) or sham surgery (n=4) via a median sternotomy. Neurologic function was graded by Basso Motor Score (BMS) preoperatively and at 24h intervals after reperfusion. Mice appearing functionally normal and sham mice were placed on a walking beam and recorded on high-definition, for single-frame motion analysis. After 96hrs, spinal cords were removed for histological analysis. Following 3min of ischemia, functional outcomes were split evenly with either mice displaying almost normal function n=7 or near complete paraplegia n=7. Additionally, single-frame motion analysis revealed significant changes in gait. Histologically, there was a significant stepwise reduction of neuronal viability, with even the normal function ischemic group demonstrating significant loss of neurons. Despite the appearance of normal function, temporary ischemia induced marked cyto-architectural changes and neuronal degeneration. Furthermore high-definition gait analysis revealed significant changes in gait and activity following thoracic aortic occlusion. These data suggest that all patients undergoing procedures, even with short ischemic times, may have spinal cord injury that is not evident clinically. Copyright © 2015 Elsevier B.V. All rights reserved.
    Brain research 05/2015; 1618. DOI:10.1016/j.brainres.2015.04.053 · 2.83 Impact Factor
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    ABSTRACT: Paraplegia remains a devastating complication of aortic surgery, occurring in up to 20% of complex thoracoabdominal repairs. Erythropoietin (EPO) attenuates this injury in models of spinal cord ischemia. Upregulation of the beta-common receptor (βcR) subunit of the EPO receptor is associated with reduced damage in murine models of neural injury. This receptor activates anti-apoptotic pathways including signaling transducer and activator of transcription 3 (STAT3). We hypothesized that spinal cord ischemia-reperfusion injury upregulates the βcR subunit with a subsequent increase in activated STAT3. Adult male C57/BL6 mice received an intraperitoneal injection of 0.5 mL of EPO (10 U/kg) or 0.9% saline after induction of anesthesia. Spinal cord ischemia was induced through sternotomy and 4-minute thoracic aortic cross-clamp. Sham mice underwent sternotomy without cross-clamp placement. Four groups were studied: ischemic and sham groups, each with and without EPO treatment. After 4 hours of reperfusion, spinal cords were harvested and homogenized. The βcR subunit expression and STAT3 activation were evaluated by immunoblot. Ischemia reperfusion increased βcR subunit expression in spinal cords of ischemia + saline and ischemia + EPO mice compared with shams (3.4 ± 1.39 vs 1.31 ± 0.3, p = 0.01 and 3.80 ± 0.58 vs 1.56 ± 0.32, p = 0.01). Additionally, both ischemic groups demonstrated increased STAT3 activation compared with shams (1.35 ± 0.14 vs 1.09 ± 0.07, p = 0.01 and 1.66 ± 0.35 vs 1.08 ± 0.17, p = 0.02). Ischemia-reperfusion injury induces EPO receptor βcR subunit expression and early downstream anti-apoptotic signaling through STAT3 activation. Further investigation into the role of the βcR subunit is warranted to determine tissue protective functions of EPO. Elucidation of mechanisms involved in spinal cord protection is essential for reducing delayed paraplegia. Copyright © 2015 The Society of Thoracic Surgeons. Published by Elsevier Inc. All rights reserved.
    The Annals of thoracic surgery 04/2015; DOI:10.1016/j.athoracsur.2015.01.027 · 3.65 Impact Factor
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    ABSTRACT: The aortic valve interstitial cell (AVIC) has been implicated in the pathogenesis of aortic stenosis. In response to proinflammatory stimulation, the AVIC undergoes a phenotypic change from that of a myofibroblast phenotype to that of osteoblast-like cell. Matrix Gla-protein (MGP) has been identified as an important inhibitor of vascular calcification. We therefore hypothesized that MGP expression is reduced in diseased AVICs, and loss of this protective protein contributes to calcification of the aortic valve. Our purpose was to compare MGP expression in normal versus diseased AVICs. Human AVICs were isolated from normal aortic valves from explanted hearts (n = 6) at the time of heart transplantation. AVICs were also isolated from calcified, diseased valves of patients (n = 6) undergoing aortic valve replacement. AVICs were grown in culture until they reached passages 2-6 before experimentation. Immunofluorescent staining, reverse transcriptase-polymerase chain reaction, immunoblotting, and enzyme-linked immunosorbent assay were used to compare levels of MGP in normal and diseased AVICs. Statistics were performed using the Mann-Whitney U test (P < 0.05). MGP expression was significantly decreased in diseased AVICs relative to normal AVICs by immunofluorescent staining, reverse transcriptase-polymerase chain reaction, immunoblotting, and enzyme-linked immunosorbent assay. An important anti-calcification defense mechanism is deficient in calcified aortic valves. MGP expression is significantly lower in diseased relative to normal AVICs. Lack of this important "anti-calcification" protein may contribute to calcification of the aortic valve. Copyright © 2015 Elsevier Inc. All rights reserved.
    Journal of Surgical Research 04/2015; DOI:10.1016/j.jss.2015.04.076 · 2.12 Impact Factor
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    ABSTRACT: The signaling mechanism that mediates inflammatory responses in remote non-ischemic myocardium following regional ischemia/reperfusion (I/R) remains incompletely understood. Myocardial Toll-like receptor 4 (TLR4) can be activated by multiple proteins released from injured cells and plays a role in myocardial inflammation and injury expansion. We tested the hypothesis that TLR4 occupies an important role in mediating the inflammatory responses and matrix protein remodeling in the remote non-ischemic myocardium following regional I/R injury. TLR4-defective (C3H/HeJ) and TLR4-competent (C3H/HeN) mice were subjected to coronary artery ligation (30 min) and reperfusion for 1, 3, 7 or 14 days. In TLR4-competent mice, levels of monocyte chemoattractant protein -1 (MCP-1), keratinocyte chemoattractant (KC), intercellular adhesion molecule 1 (ICAM-1) and vascular cell adhesion molecule 1 (VCAM-1) were elevated in the remote non-ischemic myocardium at day 1, 3, and 7 of reperfusion. Levels of collagen I, collagen IV, matrix metalloproteinase (MMP) 2 and MMP 9 were increased in the remote non-ischemic myocardium at day 7 and 14 of reperfusion. MMP 2 and MMP 9 activities were also increased. TLR4 deficiency resulted in a moderate reduction in myocardial infarct size. However, it markedly downgraded the changes in the levels of chemokines, adhesion molecules and matrix proteins in the remote non-ischemic myocardium. Further, left ventricular function at day 14 was significantly improved in TLR4-defective mice. In conclusion, TLR4 mediates the inflammatory responses and matrix protein remodeling in the remote non-ischemic myocardium following regional myocardial I/R injury and contributes to the mechanism of adverse cardiac remodeling.
    PLoS ONE 03/2015; 10(3):e0121853. DOI:10.1371/journal.pone.0121853 · 3.53 Impact Factor
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    ABSTRACT: Calcific aortic valve disease (CAVD) is characterized by chronic inflammation and progressive calcification in valve leaflets. Aortic valve interstitial cells (AVICs) play a critical role in the pathogenesis of CAVD. Previous studies show that stimulation of Toll-like receptor (TLR) 2 or TLR4 in AVICs in vitro up-regulates the expression of osteogenic mediators. Double-stranded RNA (dsRNA) can activate pro-inflammatory signaling through TLR3, the NLRP3 inflammasome and RIG-I-like receptors. The objective of this study is to determine the effect of dsRNA on AVIC osteogenic activities and the mechanism of its action. AVICs isolated from normal human valves were exposed to polyinosinic-polycytidylic acid [poly(I:C)], a mimic of dsRNA. Treatment with poly(I:C) increased the production of bone morphogenetic protein-2 (BMP-2), transforming growth factor beta-1 (TGF-β1) and alkaline phosphatase (ALP), and resulted in calcium deposit formation. Poly(I:C) induced the phosphorylation of NF-κB and ERK1/2. Knockdown of TLR3 essentially abrogated NF-κB and ERK1/2 phosphorylation, and markedly reduced the effect of poly(I:C) on the production of BMP-2, TGF-β1 and ALP. Further, inhibition of either NF-κB or ERK1/2 markedly reduced the levels of BMP-2, TGF-β1 and ALP in cells exposed to poly(I:C). Poly(I:C) up-regulates the production of BMP-2, TGF-β1 and ALP, and promotes calcium deposit formation in human AVICs. The pro-osteogenic effect of poly(I:C) is mediated primarily by TLR3 and the NF-κB and ERK1/2 pathways. These findings suggest that dsRNA, when present in aortic valve tissue, may promote CAVD progression through up-regulation of AVIC osteogenic activities.
    International journal of biological sciences 01/2015; 11(4):482-93. DOI:10.7150/ijbs.10905 · 4.37 Impact Factor
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    ABSTRACT: Paraplegia secondary to spinal cord ischemia-reperfusion injury remains a devastating complication of thoracoabdominal aortic intervention. The complex interactions between injured neurons and activated leukocytes have limited the understanding of neuron-specific injury. We hypothesize that spinal cord neuron cell cultures subjected to oxygen-glucose deprivation (OGD) would simulate ischemia-reperfusion injury, which could be attenuated by specific alpha-2a agonism in an Akt-dependent fashion. Spinal cords from perinatal mice were harvested, and neurons cultured in vitro for 7-10 d. Cells were pretreated with 1 μM dexmedetomidine (Dex) and subjected to OGD in an anoxic chamber. Viability was determined by MTT assay. Deoxyuridine-triphosphate nick-end labeling staining and lactate dehydrogenase (LDH) assay were used for apoptosis and necrosis identification, respectively. Western blot was used for protein analysis. Vehicle control cells were only 59% viable after 1 h of OGD. Pretreatment with Dex significantly preserves neuronal viability with 88% viable (P < 0.05). Dex significantly decreased apoptotic cells compared with that of vehicle control cells by 50% (P < 0.05). Necrosis was not significantly different between treatment groups. Mechanistically, Dex treatment significantly increased phosphorylated Akt (P < 0.05), but protective effects of Dex were eliminated by an alpha-2a antagonist or Akt inhibitor (P < 0.05). Using a novel spinal cord neuron cell culture, OGD mimics neuronal metabolic derangement responsible for paraplegia after aortic surgery. Dex preserves neuronal viability and decreases apoptosis in an Akt-dependent fashion. Dex demonstrates clinical promise for reducing the risk of paraplegia after high-risk aortic surgery. Copyright © 2015 Elsevier Inc. All rights reserved.
    Journal of Surgical Research 12/2014; 195(1). DOI:10.1016/j.jss.2014.12.033 · 2.12 Impact Factor
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    ABSTRACT: Biglycan accumulates in aortic valves affected by calcific aortic valve disease (CAVD), and soluble biglycan upregulates BMP-2 expression in human aortic valve interstitial cells (AVICs) via Toll-like receptor (TLR) 2 and induces AVIC pro-osteogenic reprogramming, characterized by elevated pro-osteogenic activities. We sought to identify the factors responsible for biglycan-induced pro-osteogenic reprogramming in human AVICs. Treatment of AVICs with recombinant biglycan induced the secretion of BMP-2 and TGF-β1, but not BMP-4 or BMP-7. Biglycan upregulated TGF-β1 expression in a TLR4-dependent fashion. Neutralization of BMP-2 or TGF-β1 attenuated the expression of alkaline phosphatase (ALP), osteopontin, and runt-related transcription factor 2 (Runx2) in cells exposed to biglycan. However, neutralization of both BMP-2 and TGF-β1 abolished the expression of these osteogenic biomarkers and calcium deposition. Phosphorylated Smad1 and Smad3 were detected in cells exposed to biglycan, and knockdown of Smad1 or Smad3 attenuated the effect of biglycan on the expression of osteogenic biomarkers. While BMP-2 and TGF-β1 each upregulated the expression of osteogenic biomarkers, an exposure to BMP-2 plus TGF-β1 induced a greater upregulation and results in calcium deposition. We conclude that concurrent upregulation of BMP-2 and TGF-β1 is responsible for biglycan-induced pro-osteogenic reprogramming in human AVICs. The Smad 1/3 pathways are involved in the mechanism of AVIC pro-osteogenic reprogramming. Biglycan upregulates BMP-2 and TGF-β1 in human aortic valve cells through TLRs. Both BMP-2 and TGF-β1 are required for aortic valve cell pro-osteogenic reprogramming. Smad signaling pathways are involved in mediating the pro-osteogenic effects of biglycan.
    Journal of Molecular Medicine 11/2014; 93(4). DOI:10.1007/s00109-014-1229-z · 4.74 Impact Factor
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    ABSTRACT: Paraplegia remains a devastating complication of complex aortic surgery. Erythropoietin (EPO) has been shown to prevent paraplegia after ischemia reperfusion, but the protective mechanism remains poorly described in the spinal cord. We hypothesized that EPO induces the CREB (cAMP [adenosine 3'5' cyclic monophosphate] response element-binding protein) pathway and neurotrophin production in the murine spinal cord, attenuating functional and cellular injury. Adult male mice were subjected to 4 minutes of spinal cord ischemia via an aortic and left subclavian cross-clamp. Experimental groups included EPO treatment 4 hours before incision (n = 7), ischemic control (n = 7), and shams (n = 4). Hind-limb function was assessed using the Basso motor score for 48 hours after reperfusion. Spinal cords were harvested and analyzed for neuronal viability using histology and staining with a fluorescein derivative. Expression of phosphorylated (p)AKT (a serine/threonine-specific kinase), pCREB, B-cell lymphoma 2, and brain-derived neurotrophic factor were determined using immunoblotting. By 36 hours of reperfusion, EPO significantly preserved hind-limb function after ischemia-reperfusion injury (P < .01). Histology demonstrated preserved cytoarchitecture in the EPO treatment group. Cords treated with EPO expressed significant increases in pAKT (P = .021) and pCREB (P = .038). Treatment with EPO induced expression of both of the neurotrophins, B-cell lymphoma 2, and brain-derived neurotrophic factor, beginning at 12 hours. Erythropoietin-mediated induction of the CREB pathway and production of neurotrophins is associated with improved neurologic function and increased neuronal viability following spinal cord ischemia reperfusion. Further elucidation of EPO-derived neuroprotection will allow for expansion of adjunct mechanisms for spinal cord protection in high-risk thoracoabdominal aortic intervention. Copyright © 2014 The American Association for Thoracic Surgery. Published by Elsevier Inc. All rights reserved.
    Journal of Thoracic and Cardiovascular Surgery 11/2014; 149(3). DOI:10.1016/j.jtcvs.2014.11.011 · 3.99 Impact Factor
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    ABSTRACT: Aortic valve interstitial cells (AVICs) have been implicated in the pathogenesis of calcific aortic valve disease. Signal transducer and activator of transcription 3 (Stat3) possesses antiinflammatory effects. Given that calcification occurs in adult valves, we hypothesized that AVICs from adult valves more likely undergo a proosteogenic phenotypic change than those from pediatric valves and that may be related to different Stat3 activation in the response of those two age groups to toll-like receptor 4 (TLR4). AVICs from healthy human aortic valve tissues were treated with TLR4 agonist lipopolysaccharide. Cellular levels of TLR4, intercellular adhesion molecule 1, bone morphogenetic protein 2, and alkaline phosphatase, as well as phosphorylation of p-38 mitogen-activated protein kinase (MAPK), nuclear factor-κβ (NF-κβ), and Stat3, were analyzed. Toll-like receptor 4 protein levels were comparable between adult and pediatric AVICs. Adult cells produce markedly higher levels of the above markers after TLR4 stimulation, which is negatively associated with phosphorylation of Stat3. Inhibition of Stat3 enhanced p-38 MAPK and NF-κβ phosphorylation and exaggerated the expression of the above markers in pediatric AVICs after TLR4 stimulation. Adult AVICs exhibit greater inflammatory and osteogenic responses to TLR4 stimulation. The enhanced responses in adult AVICs are at least partly due to lower levels of Stat3 activation in response to TLR4 stimulation relative to pediatric cells. Stat3 functions as a negative regulator of the TLR4 responses in human AVICs. The results suggest that Stat3 activation (tyrosine phosphorylation) may be protective and that TLR4 inhibition could be targeted pharmacologically to treat calcific aortic valve disease. Copyright © 2014 The Society of Thoracic Surgeons. Published by Elsevier Inc. All rights reserved.
    The Annals of Thoracic Surgery 10/2014; DOI:10.1016/j.athoracsur.2014.07.027 · 3.63 Impact Factor
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    ABSTRACT: Delayed paraplegia secondary to ischemia-reperfusion injury is a devastating complication of thoracoabdominal aortic surgery. Alpha-2 agonists have been shown to attenuate ischemia-reperfusion injury, but the mechanism for protection has yet to be elucidated. A growing body of evidence suggests that astrocytes play a critical role in neuroprotection by release of neurotrophins. We hypothesize that alpha-2 agonism with dexmedetomidine increases glial cell-line-derived neurotrophic factor in spinal cord astrocytes to provide spinal cord protection. Spinal cords were isolated en bloc from C57BL/6 mice, and primary spinal cord astrocytes and neurons were selected for and grown separately in culture. Astrocytes were treated with dexmedetomidine, and glial cell-line-derived neurotrophic factor was tested for by enzyme-linked immunosorbent assay. The 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide assay was used to assess neuronal viability. Spinal cord primary astrocytes treated with dexmedetomidine at 1 μmol/L and 10 μmol/L had significantly increased glial cell-line-derived neurotrophic factor production compared with control (P < .05). Neurons subjected to oxygen glucose deprivation had significant preservation (P < .05) of viability with use of dexmedetomidine-treated astrocyte media. Glial cell-line-derived neurotrophic factor neutralizing antibody eliminated the protective effects of the dexmedetomidine-treated astrocyte media (P < .05). Astrocytes have been shown to preserve neuronal viability via release of neurotrophic factors. Dexmedetomidine increases glial cell-derived neurotrophic factor from spinal cord astrocytes via the alpha-2 receptor. Treatment with alpha-2 agonist dexmedetomidine may be a clinical tool for use in spinal cord protection in aortic surgery. Copyright © 2014 The American Association for Thoracic Surgery. Published by Elsevier Inc. All rights reserved.
    Journal of Thoracic and Cardiovascular Surgery 10/2014; 149(2). DOI:10.1016/j.jtcvs.2014.10.037 · 3.99 Impact Factor
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    ABSTRACT: C-terminal tensin-like (Cten) protein, a component of focal adhesions, contributes to cell motility and invasion in multiple human cancers. Epidermal growth factor can activate signal transducer and activator of transcription 3, and both contribute to invasion through focal adhesion interactions. We hypothesize that Cten may mediate invasion of lung cancer cells provided by epidermal growth factor via signal transducer and activator of transcription 3. Four human non-small cell lung cancer cell lines were treated with epidermal growth factor to evaluate activation of the signal transducer and activator of transcription 3 pathway and induction of Cten expression. Chemical inhibition of signal transducer and activator of transcription 3 was used to evaluate the effect on epidermal growth factor-induced Cten expression. Protein expression was quantified by Western blot. H125 and A549 cells were transduced with short-hairpin RNA via lentiviral vector to knockdown expression of Cten. An in vitro transwell invasion assay was used to assess the effects of Cten knockdown on cell invasion (n = 3 for all experiments). Stimulation of lung cancer cells with epidermal growth factor activated the signal transducer and activator of transcription 3 pathway and induced expression of Cten in all cell lines. Signal transducer and activator of transcription 3 inhibition significantly reduced epidermal growth factor-induced expression of Cten in H125 (P < .0001), H358 (P = .006), and H441 (P = .014) cells in a dose-dependent manner. Knockdown of Cten expression resulted in significant decreases in cellular invasion in both H125 (P = .0036) and A549 (P = .0006) cells. These are the first findings in lung cancer to demonstrate that Cten expression mediates invasion of human lung cancer cells and is upregulated by epidermal growth factor via signal transducer and activator of transcription 3 pathway. Cten should be considered a potential therapeutic target for lung cancer. Copyright © 2014 The American Association for Thoracic Surgery. Published by Elsevier Inc. All rights reserved.
    Journal of Thoracic and Cardiovascular Surgery 09/2014; 149(1). DOI:10.1016/j.jtcvs.2014.08.087 · 3.99 Impact Factor
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    ABSTRACT: IntroductionEndotoxemia and the systemic inflammatory response syndrome have a significant impact on post-surgery outcome, particularly in the elderly. The cytokine response to endotoxin is altered by aging. We tested the hypothesis that vulnerability to endotoxemic cardiac depression increases with aging due to age-related augmentation of myocardial inflammatory responses.Methods Adult (4 to 6 months) and old (20 to 22 months) C57/BL6 mice were treated with endotoxin (0.5 mg/kg, iv). Left ventricle (LV) function was assessed using a microcatheter system. Chemokines and cytokines in plasma and myocardium were analyzed by enzyme-linked immunosorbent assay (ELISA). Mononuclear cells in the myocardium were examined using immunofluorescence staining.ResultsOld mice displayed worse LV function (cardiac output: 3.0¿±¿0.2 mL/min versus 4.4¿±¿0.3 mL/min in adult mice) following endotoxin treatment. The exaggerated cardiac depression in old mice was associated with higher levels of monocyte chemoattractant protein-1 (MCP-1) and keratinocyte chemoattractant (KC) in plasma and myocardium, greater myocardial accumulation of mononuclear cells, and greater levels of tumor necrosis factor-¿ (TNF-¿), interleukin 1ß (IL-1ß) and interleukin 6 (IL-6) in plasma and myocardium. Neutralization of MCP-1 resulted in greater reductions in myocardial mononuclear cell accumulation and cytokine production, and greater improvement in LV function in old mice while neutralization of KC had a minimal effect on LV function.Conclusion Old mice have enhanced inflammatory responses to endotoxemia that lead to exaggerated cardiac functional depression. MCP-1 promotes myocardial mononuclear cell accumulation and cardiodepressant cytokines production, and plays an important role in the endotoxemic cardiomyopathy in old mice. The findings suggest that special attention is needed to protect the heart in the elderly with endotoxemia.
    Critical care (London, England) 09/2014; 18(5):527. DOI:10.1186/s13054-014-0527-8
  • David A. Fullerton, Thoralf M. Sundt
    Journal of Thoracic and Cardiovascular Surgery 09/2014; DOI:10.1016/j.jtcvs.2014.08.042 · 3.99 Impact Factor
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    ABSTRACT: Background Donor lungs acquired from victims of asphyxiation by hanging are not routinely used for lung transplantation because of the associated lung injury. Ex vivo lung perfusion (EVLP) is a technique to evaluate marginal donor lungs before transplantation. We report here our experience with the use of EVLP in donor lungs procured from victims of asphyxia by hanging. Methods Lungs from 5 donors who became brain dead secondary to hanging were evaluated by EVLP. Donor organs were perfused according to trial protocol. Donor lungs were accepted for transplantation if they maintained a PaO2 greater than or equal to 350 mm Hg, had a clear roentgenogram, and had no significant worsening of physiologic metrics. Results Perfused organs included single and double lung blocs, and all were perfused without technical incident. Three of the 5 donor organs evaluated met criteria for transplantation after 3 hours of EVLP and were transplanted. Donor organs rejected for transplantation showed either signs of worsening PaO2 or deterioration of physiologic metrics. There were no intraoperative complications in the patients who underwent transplantation, and all were alive at 30 days. Conclusions We report here the successful use of EVLP to assess donor lungs acquired from victims of asphyxiation by hanging. The use of EVLP in this particular group of donors has the potential to expand the available donor pool. We demonstrate that EVLP is a viable option for evaluating the function of lung allografts before transplantation and would recommend that all donor lungs obtained from hanging victims undergo EVLP to assess their suitability for transplantation.
    The Annals of Thoracic Surgery 09/2014; 98(3). DOI:10.1016/j.athoracsur.2014.04.102 · 3.63 Impact Factor
  • Journal of the American College of Surgeons 09/2014; 219(3):S29-S30. DOI:10.1016/j.jamcollsurg.2014.07.061 · 4.45 Impact Factor
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    ABSTRACT: Calcific aortic valve disease (CAVD) is a chronic inflammatory condition and affects a large number of elderly people. Aortic valve interstitial cells (AVICs) occupy an important role in valvular calcification and CAVD progression. While pro-inflammatory mechanisms are capable of inducing the osteogenic responses in AVICs, the molecular interaction between pro-inflammatory and pro-osteogenic mechanisms remains poorly understood. This study tested the hypothesis that intercellular adhesion molecule-1 (ICAM-1) plays a role in mediating pro-osteogenic factor expression in human AVICs. AVICs were isolated from normal human aortic valves and cultured in M199 medium. Treatment with leukocyte function-associated factor-1 (LFA-1, an ICAM-1 ligand) up-regulated the expression of bone morphogenetic protein-2 (BMP-2) and resulted in increased alkaline phosphatase activity and formation of calcification nodules. Pre-treatment with lipopolysaccharide (LPS, 0.05μg/ml) increased ICAM-1 levels on cell surfaces and exaggerated the pro-osteogenic response to LFA-1, and neutralization of ICAM-1 suppressed this response. Further, ligation of ICAM-1 by antibody cross-linking also up-regulated BMP-2 expression. Interestingly, LFA-1 elicited Notch1 cleavage and NF-κB activation. Inhibition of NF-κB markedly reduced LFA-1-induced BMP-2 expression, and inhibition of Notch1 cleavage with a γ-secretase inhibitor suppressed LFA-1-induced NF-κB activation and BMP-2 expression. Ligation of ICAM-1 on human AVICs activates the Notch1 pathway. Notch1 up-regulates BMP-2 expression in human AVICs through activation of NF-κB. The results demonstrate a novel role of ICAM-1 in translating a pro-inflammatory signal into a pro-osteogenic response in human AVICs and suggest that ICAM-1 on the surfaces of AVICs contributes to the mechanism of aortic valve calcification.
    Biochimica et Biophysica Acta (BBA) - Molecular Cell Research 08/2014; 1843(11). DOI:10.1016/j.bbamcr.2014.07.017 · 5.30 Impact Factor
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    ABSTRACT: Background Lung cancer stem cells (CSCs) are a subpopulation of cells that drive growth, invasiveness, and resistance to therapy. Inflammatory eicosanoids are critical to maintain this malignant subpopulation. Secretory phospholipase A2 group IIa (sPLA2) is an important mediator of the growth and invasive potential of human lung cancer cells and regulates eicosanoid production. We hypothesized that sPLA2 plays a role in the maintenance of lung CSCs. Methods Cancer stem cells from lung adenocarcinoma cell lines H125 and A549 were isolated using aldehyde dehydrogenase activity and flow cytometry. Protein and mRNA levels for sPLA2 were compared between sorted cells using Western blotting and quantitative reverse transcriptase–polymerase chain reaction techniques. Chemical inhibition of sPLA2 and short-hairpin RNA knockdown of sPLA2 were used to evaluate effects on tumorsphere formation. Results Lung CSCs were isolated in 8.9% ± 4.1% (mean ± SD) and 4.1% ± 1.6% of H125 and A549 cells respectively. Both sPLA2 protein and mRNA expression were significantly elevated in the CSC subpopulation of H125 (p = 0.002) and A549 (p = 0.005; n = 4). Knockdown of sPLA2 significantly reduced tumorsphere formation in H125 (p = 0.026) and A549 (p = 0.001; n = 3). Chemical inhibition of sPLA2 resulted in dose-dependent reduction in tumorsphere formation in H125 (p = 0.003) and A549 (p = 0.076; n = 3). Conclusions Lung CSCs express higher levels of sPLA2 than the non–stem cell population. Our findings that viral knockdown and chemical inhibition of sPLA2 reduce tumorsphere formation in lung cancer cells demonstrate for the first time that sPLA2 plays an important role in CSCs. These findings suggest that sPLA2 may be an important therapeutic target for human lung cancer.
    The Annals of Thoracic Surgery 08/2014; 98(2). DOI:10.1016/j.athoracsur.2014.04.044 · 3.63 Impact Factor
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    ABSTRACT: Aging exaggerates myocardial injury caused by sepsis and up-regulated the expression of cytokines. IL-37 is an anti-inflammatory cytokine, mice with transgenic expression of IL-37 are protected against endotoxic shock, exhibiting reduced lung and kidney damage. We tested the hypothesis that IL-37 protects the aging heart against endotoxemic cardiac depression via suppression of myocardial inflammatory responses. Methods: WT and IL-37 transgenic (tg) mice, males of adult (4-6 months) and aging (18-20 months), were treated with endotoxin (E. coli 011:B4; 0.5 mg/kg i.v.). Left ventricular (LV) function was measured with a pressure-volume microcatheter at 1-6 h after injection. Plasma and myocardial tissue homogenate were prepared for analysis of MCP-1, TNF-α and IL-1β by ELISA. Results: Endotoxin caused greater depression of LV function in WT aging mice, TNF-α and IL-1β in comparison to WT adult mice. Aging IL-37Tg mice had improved ejection fraction and cardiac output after LPS injection that were associated with lower myocardial levels of cytokines. To determine the role of MCP-1 in myocardial production of TNF-α and IL-1β, as well as in LV dysfunction, we treated WT aging mice with MCP-1-neutrlizing antibody and found that neutralization MCP-1 reduced myocardial TNF-α and IL-1β levels and improved LV function. Conclusions: Endotoxemia results in worse LV functional injury in aging WT mice. MCP-1 plays an important role in mediating the production of cardiac depressant cytokines and resultant LV dysfunction. IL-37 improves LV function in aging mice during endotoxemia through suppression of myocardial production of MCP-1 and cardiodepressant cytokines. Thus, IL-37 has the therapeutic potential for cardiac protection in the elderly against functional injury associated with major surgeries. cardiovascres;103/suppl_1/S92-b/CHAPTERSUB75446F1F1CHAPTERsub-75446F1 Figure: Aging IL-37 Tg mice LV function.
    Cardiovascular Research 07/2014; 103(suppl 1):S92. DOI:10.1093/cvr/cvu091.177 · 5.81 Impact Factor
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    ABSTRACT: The myocardial inflammatory response contributes to cardiac functional injury associated with heart surgery obligating global ischemia and reperfusion (I/R). Toll-like receptors (TLRs) play important roles in the mechanism underlying myocardial I/R injury. The aim of this study was to examine the release of small constitutive heat shock proteins (HSPs) from human and mouse myocardium following global ischemia and the role of extracellular small HSP in myocardial injury.
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    ABSTRACT: Mononuclear cell infiltration in valvular tissue is one of the characteristics in calcific aortic valve disease. The inflammatory responses of aortic valve interstitial cells (AVICs) play an important role in valvular inflammation. However, it remains unclear what may evoke AVIC inflammatory responses. Accumulation of biglycan has been found in diseased aortic valve leaflets. Soluble biglycan can function as a danger-associated molecular pattern to induce the production of proinflammatory mediators in cultured macrophages. We tested the hypothesis that soluble biglycan induces AVIC production of proinflammatory mediators involved in mononuclear cell infiltration through Toll-like receptor (TLR)-dependent signaling pathways.
    Inflammation Research 05/2014; 63(9). DOI:10.1007/s00011-014-0743-3 · 2.14 Impact Factor

Publication Stats

3k Citations
805.43 Total Impact Points

Institutions

  • 1995–2015
    • University of Colorado
      • • Department of Surgery
      • • Division of Cardiothoracic Surgery
      • • Department of Anesthesiology
      Denver, Colorado, United States
  • 2012–2014
    • University of Colorado at Boulder
      Boulder, Colorado, United States
  • 1998–2003
    • Northwestern University
      • • Feinberg School of Medicine
      • • Department of Surgery
      Evanston, Illinois, United States
  • 1999–2002
    • University of Illinois at Chicago
      Chicago, Illinois, United States
  • 1997
    • Northwestern Memorial Hospital
      • Department of Surgery
      Chicago, Illinois, United States
  • 1996
    • Wolfson Childrens Hospital
      Jacksonville, Florida, United States
    • San Francisco VA Medical Center
      San Francisco, California, United States
  • 1994
    • Mount Sinai Medical Center
      New York, New York, United States
  • 1991–1992
    • Children's Hospital of Richmond
      Ричмонд, Virginia, United States