Medicine and Health Sciences Commons^™

The Role Of Dlc1Β In Attenuating Cardiac Ischemia-Reperfusion Injury During Heart Transplantation, Samantha L. Collings

Electronic Thesis and Dissertation Repository

Cardiac ischemia-reperfusion injury (IRI) occurs intra-operatively during heart transplantation (HTx), underpinning graft survival. Past research implicated the PI3K/Akt1 & RhoA/ROCK pathways in IRI. Rho-GTPase activity/Akt regulates Deleted-in-liver-cancer 1 protein’s beta-isoform (DLC1β). Therefore, we hypothesized that DLC1β overexpression (OE) had anti-apoptotic effects. In vitro, HL-1 cells (mouse cardiomyocytes) received chamber hypoxia-oxygenation reperfusion (H/R) for 24H4R with/without DLC1β plasmid, before collection for protein/mRNA analyses. DLC1β-OE resulted in downregulated pro-apoptotic mRNA expression (Bax/Cycs/Casp3), upregulated protective mRNA targets (BCl2/Akt1) and less late/early apoptosis via flow cytometry. Results were confirmed via H9C2 (rat cardiomyocyte) cell lines. In vivo, C57/BL6 mice received heterotopic HTx with/without DLC1β-OE …

Cell-Free Dna Release During Programmed Cell Death In Kidney Ischemia Reperfusion Injury, Alexander Dionne

Electronic Thesis and Dissertation Repository

Transplantation is invariably associated with ischemia reperfusion injury (IRI) which causes organ dysfunction. IRI is also directly linked to several forms of programmed cell death including apoptosis and necroptosis, which increase kidney dysfunction, promote inflammation and may contribute to premature graft failure. The contribution of necroptosis and apoptosis following kidney IRI to cell-free DNA (cfDNA) generation and the potential of cfDNA to activate effectors such as NK cells involved in kidney IRI have not been defined. Our data indicate that necroptotic microvascular endothelial cells (MVECs) release considerably more cfDNA than apoptotic MVECs or untreated controls (p

Junctophilin-2 Protects Cardiomyocytes Against Palmitate-Induced Injury, Xiaoyun Ji

Electronic Thesis and Dissertation Repository

Cardiac lipotoxicity may induce cardiomyocyte apoptosis, eventually leading to myocardial dysfunction and heart failure. This study investigated whether and how junctophilin-2 (JPH2) plays a role in palmitate-induced apoptosis in cardiomyocytes. Here, we found palmitate incubation reduced JPH2 protein levels, increased cytosolic Ca²⁺ and induced apoptosis in cardiomyocytes. JPH2 over-expression prevented the increased cytosolic Ca²⁺ and apoptosis in palmitate-stimulated cardiomyocytes. JPH2 over-expression also attenuated palmitate-induced CCAAT-enhancer-binding protein homologous protein (CHOP) expression and CHOP deletion alleviated palmitate-induced apoptosis. Furthermore, blocking Ca²⁺ release from ryanodine receptor-2 (RyR2) prevented palmitate-stimulated CHOP induction and apoptosis. Additionally, JPH2 silencing elevated cytosolic Ca^{2+ …}

The Role Of Atf4 In Amyloid-Beta-Induced Neuronal Death., Gillian Petroff

Electronic Thesis and Dissertation Repository

Alzheimer’s disease (AD) is partially characterized by excessive accumulation of amyloid-b (Ab) in the brain. Ab oligomers have greater toxicity than Ab fibrils and induce neuronal stress. The Integrated Stress Response (ISR) is activated in response to cellular stress and increases expression of activating transcription factor 4 (ATF4) and its target genes. Prolonged activation has been shown to induce aberrant cell death, and increased markers of the ISR have been found in the brains of AD patients. However, the exact mechanism of amyloid-b-induced death is largely unknown. We aimed to determine if Ab-induced neuronal death occurs through ATF4-mediated upregulation of …

Effect Of Carbon Monoxide-Releasing Molecule-3 On The Severity Of Endothelial Dysfunction Due To Elevation Of Hydrostatic Pressure In An In Vitro Model Of Compartment Syndrome, Michel A. Taylor

Electronic Thesis and Dissertation Repository

Compartment syndrome (CS) is a surgical emergency caused by elevated pressure within a closed osseofascial compartment. It leads to microvascular dysfunction, limiting oxygen and nutrient delivery, gas exchange, resulting in cellular anoxia, muscle necrosis and cell death.

Currently, the only effective treatment is surgical fasciotomy. Recently, carbon monoxide (CO) delivered via carbon monoxide releasing molecule-3 (CORM-3) has been shown to improve microvascular perfusion and convey anti-inflammatory benefits in animal models of CS.

The contribution of elevated hydrostatic pressure (EHP) to the pathophysiology of CS was examined in an in vitro model of CS. We found that EHP led to increased …

Up-Regulation Of Junctophilin-2 Prevents Er Stress And Apoptosis In Hypoxia/Reoxygenation-Stimulated H9c2 Cells, Zijun Su

Electronic Thesis and Dissertation Repository

Ischemic heart disease is the leading cause of death, and reperfusion which can restore blood flow is the primary therapy. However, reperfusion can induce further damage to cardiomyocytes, a condition described as ischemia-reperfusion (I/R) injury. I/R is now recognized as a combination determining the final myocardial infarction size. Although the mechanisms underlying I/R-induced cardiac injury remain incompletely understood, emerging evidence suggests that intracellular Ca²⁺ mishandling during I/R plays a key role in cell death. Junctophilin-2 (JPH2) is a junctional membrane-binding structural protein. It mechanically maintains the fixed distance between the T-tubule and the sarcoplasmic reticulum (SR), thus allowing the …

Protective Benefits Of Hydrogen Sulfide Treatment During Renal Transplantation, Ian Lobb

Electronic Thesis and Dissertation Repository

Ischemia/reperfusion injury (IRI) is inherent to renal transplantation (RTx) and is initiated when blood supply is necessarily removed during organ procurement (ischemia) and subsequently restored upon engraftment (reperfusion). During renal ischemia, ATP depletion causes tubular epithelial cell (TEC) injury and subsequent release of pro-inflammatory mediators. Upon reperfusion, influx of O₂ causes reactive oxygen species (ROS) production and infiltration of innate immune cells which release damaging ROS and proteases. Prolonged periods of IRI are associated with increased risk of delayed graft function (DGF) and decreased long-term graft survival. The endogenously produced gasotransmitter, hydrogen sulfide (H₂S), has recently been …

Treatment Of Ischemia Reperfusion Injury With Rna Interference, Terry M. Zwiep

Electronic Thesis and Dissertation Repository

Ischemia reperfusion injury (IRI) occurs during transplantation and causes apoptosis and inflammation. The purpose of this research was to determine the effect of caspase-3, complement 3, and RelB gene silencing in the reduction of IRI using an in vitro model.

LLC-PK1 cells were used along with antimycin A for the in vitro IRI model. Prior to exposure to antimycin A, cells were transfected with caspase-3, C3, and RelB small interfering RNA (siRNA) alone or in combination and then analyzed.

The relative risk reduction of apoptosis in antimycin A treated cells with caspase-3 siRNA was 46.6% (p=0.019), RelB siRNA 42.8% (p=0.038), …

Supplementation With Hydrogen Sulfide Helps Mitigate The Effects Of Ischemia Reperfusion Injury In A Model Of Donation After Cardiac Death Renal Transplantation, Jaskirandeep Kaur Grewal

Electronic Thesis and Dissertation Repository

Donation after cardiac death (DCD) grafts experience prolonged ischemia reperfusion injury (IRI) leading to higher rates of delayed graft function and failure. Recent studies have reported protective effects of hydrogen sulfide (H₂S) against IRI. Our study aims at improving DCD renal graft outcomes by H₂S supplementation in an in-vivo murine model of renal transplantation (RTx) and study the underlying mechanism in an in-vitro model using porcine kidney proximal-tubular-epithelial cells (LLC-PK1). H₂S provided survival benefit, improved renal graft function and decreased renal injury in recipient rats. In our in-vitro model of LLC-PK1 cells, H_{2 …}

Mechanisms Of Atf4-Mediated Neuronal Apoptosis, Patrick Swan

Electronic Thesis and Dissertation Repository

Abstract to be provided

Timp3 Regulation Of Macrophage Activation And Apoptosis, Michael S. Brock

Electronic Thesis and Dissertation Repository

Acute respiratory distress syndrome (ARDS) is a lung disease involving profound inflammation. Origins of persistent inflammation in select cases of ARDS are poorly understood, and we propose persistent inflammatory macrophages may be one of its mechanisms. Macrophages polarize to either promote inflammation, or suppress inflammation. Tissue inhibitor of metalloproteinases 3 (TIMP3) reduces the pro-inflammatory polarization in macrophages. Additionally, studies have shown TIMP3 promotes apoptosis, and its absence delays recovery from bleomycin-induced lung injury.

We hypothesize that TIMP3 promotes apoptosis of murine macrophages through inhibition of metalloproteinase activity and stabilization of FAS on the cell surface. Pro-inflammatory Timp3^-/- bone marrow-derived …