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Cell-free hemoglobin increases inflammation, lung apoptosis, and microvascular permeability in murine polymicrobial sepsis.
Meegan JE, Shaver CM, Putz ND, Jesse JJ, Landstreet SR, Lee HNR, Sidorova TN, McNeil JB, Wynn JL, Cheung-Flynn J, Komalavilas P, Brophy CM, Ware LB, Bastarache JA
(2020) PLoS One 15: e0228727
MeSH Terms: Animals, Apoptosis, Capillary Permeability, Endothelial Cells, Female, Hemoglobins, Humans, Inflammation, Lung, Mice, Mice, Inbred C57BL, Oxidative Stress, Sepsis
Show Abstract · Added March 3, 2020
Increased endothelial permeability is central to the pathogenesis of sepsis and leads to organ dysfunction and death but the endogenous mechanisms that drive increased endothelial permeability are not completely understood. We previously reported that cell-free hemoglobin (CFH), elevated in 80% of patients with sepsis, increases lung microvascular permeability in an ex vivo human lung model and cultured endothelial cells. In this study, we augmented a murine model of polymicrobial sepsis with elevated circulating CFH to test the hypothesis that CFH increases microvascular endothelial permeability by inducing endothelial apoptosis. Mice were treated with an intraperitoneal injection of cecal slurry with or without a single intravenous injection of CFH. Severity of illness, mortality, systemic and lung inflammation, endothelial injury and dysfunction and lung apoptosis were measured at selected time points. We found that CFH added to CS increased sepsis mortality, plasma inflammatory cytokines as well as lung apoptosis, edema and inflammation without affecting large vessel reactivity or vascular injury marker concentrations. These results suggest that CFH is an endogenous mediator of increased endothelial permeability and apoptosis in sepsis and may be a promising therapeutic target.
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13 MeSH Terms
Toll-like receptor 3-mediated inflammation by p38 is enhanced by endothelial nitric oxide synthase knockdown.
Koch SR, Choi H, Mace EH, Stark RJ
(2019) Cell Commun Signal 17: 33
MeSH Terms: Capillary Permeability, Cells, Cultured, Chemokine CXCL10, Endothelium, Vascular, Gene Knockdown Techniques, Humans, Inflammation, Interleukin-6, Interleukin-8, Nitric Oxide Synthase Type III, Poly I-C, RNA, Small Interfering, Toll-Like Receptor 3, p38 Mitogen-Activated Protein Kinases
Show Abstract · Added April 17, 2019
BACKGROUND - Vascular dysfunction is commonly seen during severe viral infections. Endothelial nitric oxide synthase (eNOS), has been postulated to play an important role in regulating vascular homeostasis as well as propagation of the inflammatory reaction. We hypothesized that the loss of eNOS would negatively impact toll-like receptor 3 (TLR3) signaling and worsen vascular function to viral challenge.
METHODS - Human microvascular endothelial cells (HMVECs) were exposed to either control or eNOS siRNA and then treated with Poly I:C, a TLR3 agonist and mimicker of dsRNA viruses. Cells were assessed for protein-protein associations, cytokine and chemokine analysis as well as transendothelial electrical resistance (TEER) as a surrogate of permeability.
RESULTS - HMVECs that had reduced eNOS expression had a significantly elevated increase in IL-6, IL-8 and IP-10 production after Poly I:C. In addition, the knockdown of eNOS enhanced the change in TEER after Poly I:C stimulation. Western blot analysis showed enhanced phosphorylation of p38 in sieNOS treated cells with Poly I:C compared to siControl cells. Proximity ligation assays further demonstrated direct eNOS-p38 protein-protein interactions. The addition of the p38 inhibitor, SB203580, in eNOS knockdown cells reduced both cytokine production after Poly I:C, and as well as mitigated the reduction in TEER, suggesting a direct link between eNOS and p38 in TLR3 signaling.
CONCLUSIONS - These results suggest that reduction of eNOS increases TLR3-mediated inflammation in human endothelial cells in a p38-dependent manner. This finding has important implications for understanding the pathogenesis of severe viral infections and the associated vascular dysfunction.
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14 MeSH Terms
Rapid changes in the microvascular circulation of skeletal muscle impair insulin delivery during sepsis.
Mignemi NA, McClatchey PM, Kilchrist KV, Williams IM, Millis BA, Syring KE, Duvall CL, Wasserman DH, McGuinness OP
(2019) Am J Physiol Endocrinol Metab 316: E1012-E1023
MeSH Terms: Animals, Capillaries, Capillary Permeability, Disease Models, Animal, Echocardiography, Hyperglycemia, Insulin, Insulin Resistance, Lipopolysaccharides, Mice, Microcirculation, Microvessels, Muscle Fibers, Skeletal, Muscle, Skeletal, Sepsis
Show Abstract · Added March 26, 2019
Sepsis costs the healthcare system $23 billion annually and has a mortality rate between 10 and 40%. An early indication of sepsis is the onset of hyperglycemia, which is the result of sepsis-induced insulin resistance in skeletal muscle. Previous investigations have focused on events in the myocyte (e.g., insulin signaling and glucose transport and subsequent metabolism) as the causes for this insulin-resistant state. However, the delivery of insulin to the skeletal muscle is also an important determinant of insulin action. Skeletal muscle microvascular blood flow, which delivers the insulin to the muscle, is known to be decreased during sepsis. Here we test whether the reduced capillary blood flow to skeletal muscle belies the sepsis-induced insulin resistance by reducing insulin delivery to the myocyte. We hypothesize that decreased capillary flow and consequent decrease in insulin delivery is an early event that precedes gross cardiovascular alterations seen with sepsis. This hypothesis was examined in mice treated with either lipopolysaccharide (LPS) or polymicrobial sepsis followed by intravital microscopy of the skeletal muscle microcirculation. We calculated insulin delivery to the myocyte using two independent methods and found that LPS and sepsis rapidly reduce insulin delivery to the skeletal muscle by ~50%; this was driven by decreases in capillary flow velocity and the number of perfused capillaries. Furthermore, the changes in skeletal muscle microcirculation occur before changes in both cardiac output and arterial blood pressure. These data suggest that a rapid reduction in skeletal muscle insulin delivery contributes to the induction of insulin resistance during sepsis.
1 Communities
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15 MeSH Terms
Lipopolysaccharide Induced Opening of the Blood Brain Barrier on Aging 5XFAD Mouse Model.
Barton SM, Janve VA, McClure R, Anderson A, Matsubara JA, Gore JC, Pham W
(2019) J Alzheimers Dis 67: 503-513
MeSH Terms: Aging, Alzheimer Disease, Amyloid beta-Peptides, Animals, Benzothiazoles, Biological Availability, Blood-Brain Barrier, Ferric Compounds, Humans, Inflammation, Lipopolysaccharides, Mice, Mice, Inbred C57BL, Mice, Transgenic, Nanoparticles, Permeability, Plaque, Amyloid
Show Abstract · Added March 26, 2019
The development of neurotherapeutics for many neurodegenerative diseases has largely been hindered by limited pharmacologic penetration across the blood-brain barrier (BBB). Previous attempts to target and clear amyloid-β (Aβ) plaques, a key mediator of neurodegenerative changes in Alzheimer's disease (AD), have had limited clinical success due to low bioavailability in the brain because of the BBB. Here we test the effects of inducing an inflammatory response to disrupt the BBB in the 5XFAD transgenic mouse model of AD. Lipopolysaccharide (LPS), a bacterial endotoxin recognized by the innate immune system, was injected at varying doses. 24 hours later, mice were injected with either thioflavin S, a fluorescent Aβ-binding small molecule or 30 nm superparamagnetic iron oxide (SPIO) nanoparticles, both of which are unable to penetrate the BBB under normal physiologic conditions. Our results showed that when pretreated with 3.0 mg/kg LPS, thioflavin S can be found in the brain bound to Aβ plaques in aged 5XFAD transgenic mice. Following the same LPS pretreatment, SPIO nanoparticles could also be found in the brain. However, when done on wild type or young 5XFAD mice, limited SPIO was detected. Our results suggest that the BBB in aged 5XFAD mouse model is susceptible to increased permeability mediated by LPS, allowing for improved delivery of the small molecule thioflavin S to target Aβ plaques and SPIO nanoparticles, which are significantly larger than antibodies used in clinical trials for immunotherapy of AD. Although this approach demonstrated efficacy for improved delivery to the brain, LPS treatment resulted in significant weight loss even at low doses, resulting from the induced inflammatory response. These findings suggest inducing inflammation can improve delivery of small and large materials to the brain for improved therapeutic or diagnostic efficacy. However, this approach must be balanced with the risks of systemic inflammation.
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17 MeSH Terms
Matrix stiffness regulates vascular integrity through focal adhesion kinase activity.
Wang W, Lollis EM, Bordeleau F, Reinhart-King CA
(2019) FASEB J 33: 1199-1208
MeSH Terms: Adherens Junctions, Animals, Antigens, CD, Cadherins, Capillary Permeability, Chick Embryo, Endothelium, Vascular, Enzyme Activation, Extracellular Matrix, Female, Focal Adhesion Protein-Tyrosine Kinases, Human Umbilical Vein Endothelial Cells, Humans, Mice, Mice, Transgenic, Phosphorylation, Protein Transport, Tyrosine, src-Family Kinases
Show Abstract · Added April 10, 2019
Tumor vasculature is known to be more permeable than the vasculature found in healthy tissue, which in turn can lead to a more aggressive tumor phenotype and impair drug delivery into tumors. While the stiffening of the stroma surrounding solid tumors has been reported to increase vascular permeability, the mechanism of this process remains unclear. Here, we utilize an in vitro model of tumor stiffening, ex ovo culture, and a mouse model to investigate the molecular mechanism by which matrix stiffening alters endothelial barrier function. Our data indicate that the increased endothelial permeability caused by heightened matrix stiffness can be prevented by pharmaceutical inhibition of focal adhesion kinase (FAK) both in vitro and ex ovo. Matrix stiffness-mediated FAK activation determines Src localization to cell-cell junctions, which then induces increased vascular endothelial cadherin phosphorylation both in vitro and in vivo. Endothelial cells in stiff tumors have more activated Src and higher levels of phosphorylated vascular endothelial cadherin at adherens junctions compared to endothelial cells in more compliant tumors. Altogether, our data indicate that matrix stiffness regulates endothelial barrier integrity through FAK activity, providing one mechanism by which extracellular matrix stiffness regulates endothelial barrier function. Additionally, our work also provides further evidence that FAK is a promising potential target for cancer therapy because FAK plays a critical role in the regulation of endothelial barrier integrity.-Wang, W., Lollis, E. M., Bordeleau, F., Reinhart-King, C. A. Matrix stiffness regulates vascular integrity through focal adhesion kinase activity.
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19 MeSH Terms
BVES is required for maintenance of colonic epithelial integrity in experimental colitis by modifying intestinal permeability.
Choksi YA, Reddy VK, Singh K, Barrett CW, Short SP, Parang B, Keating CE, Thompson JJ, Verriere TG, Brown RE, Piazuelo MB, Bader DM, Washington MK, Mittal MK, Brand T, Gobert AP, Coburn LA, Wilson KT, Williams CS
(2018) Mucosal Immunol 11: 1363-1374
MeSH Terms: Adult, Animals, Caco-2 Cells, Cell Adhesion Molecules, Cell Line, Cell Line, Tumor, Citrobacter rodentium, Coculture Techniques, Colitis, Ulcerative, Colon, Dextran Sulfate, Epithelial Cells, Escherichia coli, Female, HEK293 Cells, Humans, Intestinal Absorption, Intestinal Mucosa, Male, Membrane Proteins, Mice, Mice, Inbred C57BL, Middle Aged, Muscle Proteins, Permeability, RNA, Messenger, Signal Transduction, Tight Junctions
Show Abstract · Added June 23, 2018
Blood vessel epicardial substance (BVES), or POPDC1, is a tight junction-associated transmembrane protein that modulates epithelial-to-mesenchymal transition (EMT) via junctional signaling pathways. There have been no in vivo studies investigating the role of BVES in colitis. We hypothesized that BVES is critical for maintaining colonic epithelial integrity. At baseline, Bves mouse colons demonstrate increased crypt height, elevated proliferation, decreased apoptosis, altered intestinal lineage allocation, and dysregulation of tight junctions with functional deficits in permeability and altered intestinal immunity. Bves mice inoculated with Citrobacter rodentium had greater colonic injury, increased colonic and mesenteric lymph node bacterial colonization, and altered immune responses after infection. We propose that increased bacterial colonization and translocation result in amplified immune responses and worsened injury. Similarly, dextran sodium sulfate (DSS) treatment resulted in greater histologic injury in Bves mice. Two different human cell lines (Caco2 and HEK293Ts) co-cultured with enteropathogenic E. coli showed increased attaching/effacing lesions in the absence of BVES. Finally, BVES mRNA levels were reduced in human ulcerative colitis (UC) biopsy specimens. Collectively, these studies suggest that BVES plays a protective role both in ulcerative and infectious colitis and identify BVES as a critical protector of colonic mucosal integrity.
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3 Members
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28 MeSH Terms
Functional features of the "finger" domain of the DEG/ENaC channels MEC-4 and UNC-8.
Matthewman C, Johnson CK, Miller DM, Bianchi L
(2018) Am J Physiol Cell Physiol 315: C155-C163
MeSH Terms: Amino Acid Sequence, Animals, Calcium, Cell Death, Cell Membrane Permeability, Epithelial Sodium Channels, Magnesium, Membrane Proteins, Mutation, Oocytes, Protein Transport, Sodium, Xenopus laevis
Show Abstract · Added March 26, 2019
UNC-8 and MEC-4 are two members of the degenerin/epithelial Na channel (DEG/ENaC) family of voltage-independent Na channels that share a high degree of sequence homology and functional similarity. For example, both can be hyperactivated by genetic mutations [UNC-8(d) and MEC-4(d)] that induce neuronal death by necrosis. Both depend in vivo on chaperone protein MEC-6 for function, as demonstrated by the finding that neuronal death induced by hyperactive UNC-8 and MEC-4 channels is prevented by null mutations in mec-6. UNC-8 and MEC-4 differ functionally in three major ways: 1) MEC-4 is calcium permeable, whereas UNC-8 is not; 2) UNC-8, but not MEC-4, is blocked by extracellular calcium and magnesium in the micromolar range; and 3) MEC-6 increases the number of MEC-4 channels at the cell surface in oocytes but does not have this effect on UNC-8. We previously reported that Capermeability of MEC-4 is conferred by the second transmembrane domain. We show here that the extracellular "finger" domain of UNC-8 is sufficient to mediate inhibition by divalent cations and that regulation by MEC-6 also depends on this region. Thus, our work confirms that the finger domain houses residues involved in gating of this channel class and shows for the first time that the finger domain also mediates regulation by chaperone protein MEC-6. Given that the finger domain is the most divergent region across the DEG/ENaC family, we speculate that it influences channel trafficking and function in a unique manner depending on the channel subunit.
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13 MeSH Terms
Epithelial Heparan Sulfate Contributes to Alveolar Barrier Function and Is Shed during Lung Injury.
Haeger SM, Liu X, Han X, McNeil JB, Oshima K, McMurtry SA, Yang Y, Ouyang Y, Zhang F, Nozik-Grayck E, Zemans RL, Tuder RM, Bastarache JA, Linhardt RJ, Schmidt EP
(2018) Am J Respir Cell Mol Biol 59: 363-374
MeSH Terms: Animals, Capillary Permeability, Endothelium, Vascular, Glycocalyx, Heparitin Sulfate, Lipopolysaccharides, Lung Injury, Mice, Respiratory Distress Syndrome, Adult, Syndecans
Show Abstract · Added May 31, 2018
The lung epithelial glycocalyx is a carbohydrate-enriched layer lining the pulmonary epithelial surface. Although epithelial glycocalyx visualization has been reported, its composition and function remain unknown. Using immunofluorescence and mass spectrometry, we identified heparan sulfate (HS) and chondroitin sulfate within the lung epithelial glycocalyx. In vivo selective enzymatic degradation of epithelial HS, but not chondroitin sulfate, increased lung permeability. Using mass spectrometry and gel electrophoresis approaches to determine the fate of epithelial HS during lung injury, we detected shedding of 20 saccharide-long or greater HS into BAL fluid in intratracheal LPS-treated mice. Furthermore, airspace HS in clinical samples from patients with acute respiratory distress syndrome correlated with indices of alveolar permeability, reflecting the clinical relevance of these findings. The length of HS shed during intratracheal LPS-induced injury (≥20 saccharides) suggests cleavage of the proteoglycan anchoring HS to the epithelial surface, rather than cleavage of HS itself. We used pharmacologic and transgenic animal approaches to determine that matrix metalloproteinases partially mediate HS shedding during intratracheal LPS-induced lung injury. Although there was a trend toward decreased alveolar permeability after treatment with the matrix metalloproteinase inhibitor, doxycycline, this did not reach statistical significance. These studies suggest that epithelial HS contributes to the lung epithelial barrier and its degradation is sufficient to increase lung permeability. The partial reduction of HS shedding achieved with doxycycline is not sufficient to rescue epithelial barrier function during intratracheal LPS-induced lung injury; however, whether complete attenuation of HS shedding is sufficient to rescue epithelial barrier function remains unknown.
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10 MeSH Terms
Cell-free hemoglobin promotes primary graft dysfunction through oxidative lung endothelial injury.
Shaver CM, Wickersham N, McNeil JB, Nagata H, Miller A, Landstreet SR, Kuck JL, Diamond JM, Lederer DJ, Kawut SM, Palmer SM, Wille KM, Weinacker A, Lama VN, Crespo MM, Orens JB, Shah PD, Hage CA, Cantu E, Porteous MK, Dhillon G, McDyer J, Bastarache JA, Christie JD, Ware LB, Lung Transplant Outcomes Group (LTOG)
(2018) JCI Insight 3:
MeSH Terms: Acetaminophen, Allografts, Capillary Permeability, Case-Control Studies, Cell Line, Endothelial Cells, Female, Hemoglobins, Humans, Hyperoxia, Lung, Lung Transplantation, Male, Microvessels, Middle Aged, Oxidative Stress, Primary Graft Dysfunction
Show Abstract · Added May 31, 2018
Primary graft dysfunction (PGD) is acute lung injury within 72 hours of lung transplantation. We hypothesized that cell-free hemoglobin (CFH) contributes to PGD by increasing lung microvascular permeability and tested this in patients, ex vivo human lungs, and cultured human lung microvascular endothelial cells. In a nested case control study of 40 patients with severe PGD at 72 hours and 80 matched controls without PGD, elevated preoperative CFH was independently associated with increased PGD risk (odds ratio [OR] 2.75, 95%CI, 1.23-6.16, P = 0.014). The effect of CFH on PGD was magnified by reperfusion fraction of inspired oxygen (FiO2) ≥ 0.40 (OR 3.41, P = 0.031). Isolated perfused human lungs exposed to intravascular CFH (100 mg/dl) developed increased vascular permeability as measured by lung weight (CFH 14.4% vs. control 0.65%, P = 0.047) and extravasation of Evans blue-labeled albumin dye (EBD) into the airspace (P = 0.027). CFH (1 mg/dl) also increased paracellular permeability of human pulmonary microvascular endothelial cell monolayers (hPMVECs). Hyperoxia (FiO2 = 0.95) increased human lung and hPMVEC permeability compared with normoxia (FiO2 = 0.21). Treatment with acetaminophen (15 μg/ml), a specific hemoprotein reductant, prevented CFH-dependent permeability in human lungs (P = 0.046) and hPMVECs (P = 0.037). In summary, CFH may mediate PGD through oxidative effects on microvascular permeability, which are augmented by hyperoxia and abrogated by acetaminophen.
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17 MeSH Terms
The Role of Aquaporins in Ocular Lens Homeostasis.
Schey KL, Petrova RS, Gletten RB, Donaldson PJ
(2017) Int J Mol Sci 18:
MeSH Terms: Animals, Aquaporins, Biological Transport, Active, Eye Proteins, Homeostasis, Humans, Lens, Crystalline, Permeability, Protein Isoforms, Water
Show Abstract · Added April 3, 2018
Aquaporins (AQPs), by playing essential roles in the maintenance of ocular lens homeostasis, contribute to the establishment and maintenance of the overall optical properties of the lens over many decades of life. Three aquaporins, AQP0, AQP1 and AQP5, each with distinctly different functional properties, are abundantly and differentially expressed in the different regions of the ocular lens. Furthermore, the diversity of AQP functionality is increased in the absence of protein turnover by age-related modifications to lens AQPs that are proposed to alter AQP function in the different regions of the lens. These regional differences in AQP functionality are proposed to contribute to the generation and directionality of the lens internal microcirculation; a system of circulating ionic and fluid fluxes that delivers nutrients to and removes wastes from the lens faster than could be achieved by passive diffusion alone. In this review, we present how regional differences in lens AQP isoforms potentially contribute to this microcirculation system by highlighting current areas of investigation and emphasizing areas where future work is required.
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10 MeSH Terms