Life Sciences Commons^™

Immunomodulatory Effects Of Resolvin D2 In A Model Of Infection, Prem Yugandhar Kadiyam Sundarasivarao

Graduate School of Biomedical Sciences Theses and Dissertations

Dysregulated hyperinflammatory host immune response to underlying bacterial infections is a characteristic of sepsis. In sepsis, bacteria often trigger abnormal hyperinflammatory responses which can cause multiple organ failure and if sustained can lead to an immunosuppressive phase where the host is susceptible to secondary infections caused by opportunistic bacteria like Pseudomonas aeruginosa (P. aeruginosa). In our studies, we used a 2-hit model of cecal ligation and puncture (CLP) followed by P. aeruginosa secondary lung infection to investigate cellular and molecular mechanisms in the beneficial action of resolvin D2 (RvD2). Resolvins of the D-series are a group of fatty acids known …

Targeting The Cerebrovasculature In Sepsis: A Focus On The Brain Microvascular Endothelium, Divine C. Nwafor

Graduate Theses, Dissertations, and Problem Reports

The blood-brain barrier (BBB) is a critical interface between the systemic circulation and the brain. It is a specialized multicellular unit composed of brain microvascular endothelial cells (BMECs), pericytes, a basement membrane, and astrocytic end foot processes. BMECs are a principal component of the BBB that provide the structural framework needed for the stringent transport of molecules into the brain. BMEC dysfunction permits the trafficking of neurotoxins from systemic circulation into the brain, which ultimately exacerbates BBB dysfunction and neuroinflammation. Studies have shown that BBB dysfunction is a key determinant of cognitive decline in sepsis. However, there are critical knowledge …

The Role Of Regulator Of G Protein Signaling 2 In Inflammatory Cytokine Release In Endotoxemia In Mice, Xin Tong Ma

Electronic Thesis and Dissertation Repository

In sepsis, lipopolysaccharide (LPS) activates toll-like receptor 4 to stimulate the release of inflammatory cytokines (e.g. tumor necrosis factor-alpha, TNF-α), leading to cardiac dysfunction. Regulator of G protein signaling 2 (RGS2) limits G protein-coupled receptor signaling by increasing the rate of G protein deactivation or inhibiting G protein-effector interactions. We hypothesized that RGS2 deficiency would enhance proinflammatory responses in endotoxemia. Adult wild-type and RGS2^-/- C57BL/6 mice and neonatal cardiomyocytes were treated with LPS and assessed for inflammatory responses and cardiac function. Myocardial TNF-α expression was higher in RGS2^-/- mice during endotoxemia. Additionally, cardiac function was impaired in …

Development, Expansion And Role Of Myeloid-Derived Suppressor Cells In Post-Sepsis Immune Suppression, Tuqa Alkhateeb

Electronic Theses and Dissertations

Myeloid-derived suppressor cells (MDSCs) numbers increase significantly in sepsis and are associated with high mortality rates. These myeloid cell precursors promote immunosuppression, especially in the late (post sepsis) stage. However, the mechanisms that underlie MDSC expansion and programming are not completely understood. To investigate these mechanisms, we used a cecal-ligation and puncture (CLP) mouse model of polymicrobial sepsis that progresses from an early/acute proinflammatory phase to a late/chronic immunosuppressive phase. Previous studies in our laboratory showed that microRNA (miR)-21 and miR-181b elevate levels of the transcription factor nuclear factor 1 (NFI-A) that promotes MDSC expansion. We report here that miR-21 …

Pyocyanin, A Virulence Factor Produced By Sepsis-Causing Pseudomonas Aeruginosa, Promotes Adipose Wasting And Cachexia, Nika Larian

Theses and Dissertations--Pharmacology and Nutritional Sciences

Sepsis is a leading cause of death among critically ill patients that results in metabolic alterations including hypercatabolism, lipoatrophy, and muscle wasting, contributing to the development of cachexia. Septic cachexia is associated with loss of body weight, fat mass, and lean mass and dysregulated immune function. There are currently no efficacious treatment strategies for septic cachexia, and nutritional interventions have limited success in preventing hypercatabolic wasting. Pyocyanin is a virulence factor produced by sepsis-causing Pseudomonas aeruginosa that has been shown to activate the aryl hydrocarbon receptor (AhR), increase inflammation, and produce reactive oxygen species. Thus, pyocyanin represents a novel mechanistic …

Effects Of Maternal Protein Restriction On The Pulmonary Surfactant System During The Early Life And Adulthood, Reza Khazaee

Electronic Thesis and Dissertation Repository

Fetal growth restriction (FGR) is defined by low birth weight and contributes to a variety of adult-onset diseases with different severities between males and females. However, the effects of FGR on the pulmonary surfactant are not fully elucidated. In this thesis, first, we investigated the FGR effects on the lung function and the surfactant system at the early postnatal life. It was hypothesized that FGR contributes to alterations of lung mechanics and the surfactant system during the neonatal period. Second, we assessed the FGR effects on the surfactant system in response to sepsis in adulthood. It was hypothesized that FGR …

Biomarkers Of Sepsis: A Retrospective Approach, Jose M. Roberts

Williams Honors College, Honors Research Projects

Background: Biomarkers are taking the spotlight in becoming the norm for early diagnoses. Sepsis is an inflammatory disease that increases metabolic rate in children. The first biomarker is hyponatremia. Hyponatremia is a frequent electrolyte imbalance in clinical practice, often observed in children with inflammatory disease and infection. Presence of hyponatremia is associated with electrical signaling imbalances, inflammation and renal dysfunction. The clinical value of hyponatremia in pediatric patients is unknown. The C-reactive protein is a second biomarker. Its presence signifies that necrotic cells and inflammation are present.

Objectives: To evaluate the use of biomarkers in children seen in the Emergency …

Endothelial Hspa12b Is A Novel Protein For The Preservation Of Cardiovascular Function In Polymicrobial Sepsis Via Exosome Mir-126, Xia Zhang

Electronic Theses and Dissertations

Sepsis is the most frequent cause of mortality in most intensive care units. Cardiovascular dysfunction is a major complication associated with sepsis, with high mortality rates up to 70%. Currently, there is no effective treatment approach for sepsis.

The integrity of the endothelium is fundamental for the homeostasis of the cardiovascular system. Sepsis induces endothelial cell injury which is the key factor for multiple organ failure. The increased expression of adhesion molecules and chemokines in endothelial cell promotes leukocytes infiltration into the tissue. The loss of tight junction proteins and increased permeability of the endothelial cells will provoke tissue hypoxia …

Effect Of Ascorbate On Coagulation And Fibrinolytic Factors In The Septic Microvasculature, Scott Swarbreck

Electronic Thesis and Dissertation Repository

Sepsis, a systemic inflammatory response to an infection, is a significant cause of morbidity and mortality worldwide. The microcirculation during sepsis fails, in part, due to microthrombosis and the resulting plugging of capillaries, precipitating organ failure. Intravenous injection of ascorbate has been shown to reduce capillary plugging, however the mechanism of this protective effect is unclear. We hypothesized that ascorbate-mediated destabilization of the microthrombi through promoting fibrinolysis could contribute to this protection.

We showed that streptokinase, a pro-fibrinolytic agent, reduced the capillary plugging to a similar degree as ascorbate. This similarity provided the impetus for studying the effect of ascorbate …

The Effects Of Lipoxin A4 (Lxa4) On Neutrophil Biology In Sepsis, Benedict Wu

Graduate School of Biomedical Sciences Theses and Dissertations

During sepsis, neutrophils are inappropriately activated and have prolonged lifespans, thus becoming dysfunctional. Excessive neutrophil activation can lead to tissue injury while neutrophil dysfunction can lead to decreased free radical production and reduced phagocytosis, preventing the host from clearing preexisting infections. Lipoxin A4 (LXA4) is a specialized pro-resolution mediator which reduces neutrophil migration and expression of proinflammatory mediators. Intact neutrophil functions are critical for the host to efficiently clear invading pathogens. The effects of LXA4 on neutrophil function in sepsis have not been established. Using the cecal ligation and puncture (CLP) model of sepsis, LXA4 administered 1 h after sepsis …

Involvement Of Interleukin-33/St2 In Myocardial Dysfunction In Murine Model Of Sepsis, Yoonmi Choe

Electronic Thesis and Dissertation Repository

The disruption of myocardial extracellular matrix (ECM) has been implicated in myocardial dysfunction during sepsis. However, the underlying mechanism(s) are not clear. Interleukin-33 (IL-33) is a cytokine which regulates collagen synthesis in various cardiac pathologies. The purpose of the present study is to test whether IL-33 contributes to sepsis-induced myocardial dysfunction through regulation of matrix metalloproteinase-9 (MMP-9). The in vivo, feces-induced peritonitis (FIP) in mice and in vitro lipopolysaccharide (LPS) treatments to isolated cardiomyocytes were used. In FIP mice, myocardial IL-33 and MMP-9 expression were increased and myocardial contractility was decreased. Myocardial function in FIP mice was improved when treated …