Immunology and Infectious Disease Commons^™

Orchestrated Architecture Dismantling: Borrelia Burgdorferi’S Coordinated Destruction Of Adaptive Immune Responses, Craig A. Land

Electronic Theses and Dissertations

Borrelia burgdorferi represents the most prevalent vector-borne bacteria in North America, affecting ~476,000 Americans annually yet persisting despite robust immune responses. This project reveals spirochetes target adaptive immunity through coordinated lymphatic colonization and precision immune dysregulation.

Using comparative host models (C57BL/6 vs. reservoir Peromyscus leucopus), we demonstrate lymph node colonization within 48-hours, with spirochetes exploiting LYVE-1-positive lymphatic structures as dissemination highways while avoiding the interior of follicular regions. Critically, we identify targeted CD4+ T-cell elimination in germinal center border zones at 21-DPI, precisely when these cells should be coordinating protective immunity. Concurrent upregulation of inhibitory receptor CD32b creates molecular …

Regulation Of Cd4 T Cell Functions By Ncrna-Mediated Signaling Pathways During Chronic Viral Infections, Lam Nguyen

Electronic Theses and Dissertations

CD4 T cell homeostasis and competency are critical for the effectiveness of antiviral immunity. However, CD4 T cells derived from people living with HIV (PLWH) and individuals with chronic HCV infection often exhibit an inflammaging phenotype, evidenced by persistent inflammation, immune activation, exhaustion, senescence, and cellular apoptosis. Despite intensive investigations, the molecular mechanisms underlying CD4 T cell dysfunction in antiretroviral therapy (ART)-controlled PLWH and HCV-infected patients remain poorly understood. By investigating the roles of non-coding (nc)RNA transcripts in regulating the functions of CD4 T cells derived from PLWH and HCV-infected patients, we demonstrated that long non-coding (lnc)RNA - growth arrest-specific …

Intestinal Microbiome, Fecal Fermentation Profile, And Health Indices In Hiv Infected Men Versus Non-Infected Controls, Mary Andreae, Mary C. Andreae Mrs

Electronic Theses and Dissertations

Many HIV-positive (HIV+) males on Highly Active Anti-Retroviral Therapy (HAART) experience metabolic abnormalities, including Non-Alcoholic Fatty Liver Disease (NAFLD) and lipodystrophy. The intestinal microbiota and short chain fatty acids (SCFA), participate in bidirectional communication with their host. Dysbiosis in HIV+ males on HAART demonstrate a Prevotella-rich enterotype shaped by multiple factors including, medications, adiposity, diet, intestinal permeability, and lifestyle; our objective was to investigate these factors. 19 HIV+ and 21 HIV- males were enrolled. BMI and hip-to-waist ratio (H:W) were obtained, and FibroScan for liver health. Intestinal permeability markers Claudin-21, flagellin, and intestinal fatty acid binding protein (IFABP) in …

Effect Of Macrophage Expressed Α7 Nicotinic Acetylcholine Receptor (Α7nachr) On Migration Of Macrophages During Inflammation, Kasey Keever

Electronic Theses and Dissertations

Sepsis is a life-threatening condition characterized by overwhelming inflammation, resulting in organ system damage, leading to a high mortality rate. Care in the clinical setting is supportive, and there are no approved sepsis-specific treatments. In septic mice, activation of the cholinergic anti-inflammatory pathway decreases cytokine secretion by leukocytes and improves survival. The cholinergic anti-inflammatory pathway is a reflex of the parasympathetic nervous system, converging on the α7 nicotinic acetylcholine (α7nAChR) at the surface of macrophages. Signaling through the receptor blocks NF-kB activation, thus cytokine secretion. Receptor activation has other effects on macrophages, including modulating their migration to …

Microsporidian Spores And The Integrin Binding Loop Of The Madam Protein Are Important For Integrin Signaling And Attachment To Host Cells, Cindy L. Barrett

Electronic Theses and Dissertations

Microsporidia are a distant fungal pathogen that have severe clinical consequences for the immunocompromised. Previous work identified a microsporidian pathogen protein termed Microsporidian ADAM or MADAM. This protein has close sequence homology to other ADAM proteins (A Disintegrin and Metalloproteinase) in two microsporidian species, Encephalitozoon intestinalis and E. cuniculi. ADAM proteins have a wide range of functions, including binding to integrins and host signaling. It is known that many pathogens manipulate integrins to invade host cells, and it is predicted that microsporidia are also exploiting this host target. Previous work with the MADAM protein demonstrated that this protein has a …

Met Alterations In Glioblastoma: Characterization Of Patient-Derived Xenografts And Therapeutic Strategies, Anna Musket

Electronic Theses and Dissertations

Glioblastoma is the most commonly diagnosed central nervous system primary malignancy and it is considered a terminal diagnosis with few treatment options available. Glioblastoma tumors frequently develop treatment resistance due in part to their highly heterogenic nature. The heterogeneity of glioblastoma is partially attributed to the presence of glioma stem-like cells (GSC), which are highly invasive and resistant to chemotherapy and irradiation treatments. Signaling of the receptor tyrosine kinase MET is a known regulator of GSC. Glioblastoma patients have an increasingly poor prognosis that corresponds with increasing MET expression. Both GSC and MET are known to contribute to treatment resistance …

Comparative Characteristics Of Integrin Αdβ2 Binding To Native Fibrinogen And Fibrinogen Modified By Dha Oxidation During Inflammation, Ajibola Ilesanmi

Electronic Theses and Dissertations

2-ω-carboxyethylpyrrole (CEP) is a product of docosahexaenoic acid (DHA) oxidation, which forms covalent adducts with different proteins. CEP-modified proteins can interact with macrophage receptor, integrin αDβ2. This study aims to compare αDβ2 binding to its physiological ligand, fibrinogen, and CEP-modified fibrinogen, which is formed during inflammation. We hypothesize that modification of fibrinogen changes its ligand-binding properties to integrin αDβ2 which can affect macrophage migration and retention. Recombinant αD I-domain and αDβ2-transfected HEK293 cells were used for the experiments. Using biolayer interferometry, we found that the affinity of αD I-domain binding to fibrinogen-CEP was higher than fibrinogen and inhibited by the …

The Mechanisms Of Mitochondrial Dysfunction In T Cell Aging During Chronic Viral Infection, Madison B. Schank

Electronic Theses and Dissertations

Human immunodeficiency virus (HIV) and hepatitis C virus (HCV) infections induce a myriad of disturbances to CD4 T cell functions, including mitochondrial compromise, excessive inflammation, increased telomeric DNA damage and attrition, cellular exhaustion and senescence, and accelerated aging. In this dissertation, the mechanisms underlying metabolic failure, accelerated aging, and cellular dysfunctions were evaluated in CD4 T cells from healthy subjects (HS) treated with a telomere-targeting drug (KML001) or HCV-infected individuals or people living with HIV (PLHIV) compared to HS. We observed that KML001-induced telomere injury resulted in mitochondrial swelling and decreased mitochondrial membrane potential, cellular respiration, mitochondrial DNA (mtDNA) copy …

Investigating The Pi3k/Akt/Atm Pathway, Telomeric Dna Damage, T Cell Death, And Crispr/Cas9-Mediated Gene Editing During Acute And Chronic Hiv Infection, Sushant Khanal

Electronic Theses and Dissertations

Human Immunodeficiency Virus (HIV) infection initiates major metabolic and cell- survival complications. Anti-retroviral therapy (ART) is the current approach to suppress active HIV replication to a level of undetected viral load, but it is not a curative approach. Newer and sophisticated gene editing technologies could indeed be a potent antiviral therapy to achieve a clinical sterilization/cure of HIV infection. Chronic HIV patients, even under a successful ART regimen, exhibit a low-grade inflammation, immune senescence, premature aging, telomeric DNA attrition, T cell apoptosis, and cellular homeostasis. In this dissertation, we investigated CD4 T cell homeostasis, degree of T cell apoptosis, an …

A Functional Study Of Topological Dna Problem In Human T Cells During Chronic Viral Infection, Xindi Dang

Electronic Theses and Dissertations

T cells play an important role in adaptive immune system against viral infections, while premature aging and dysfunction of T cells induced by unrepaired DNA damages are always non-negligible snags during the long-term of fighting with chronic viral infections, such as Hepatitis B virus (HBV), Hepatitis C virus (HCV) or Human Immunodeficiency Virus (HIV) infection. In this dissertation, we investigated the role of topological DNA damage in reprogramming telomeric DNA damage responses (DDR), mitochondrial metabolisms, and T cell functions using CD4+ T cells derived from individuals with chronic viral infections or healthy subjects treated with topoisomerase inhibitors. The healthy human …

Trained Immunity Enhances The Immune Response And Maintains Microbiome Diversity In Aging And Sepsis, P. Spencer Gill

Electronic Theses and Dissertations

The global population is rapidly aging. It is estimated that over the next thirty years, the number of individuals >60 years of age will increase by over a billion, and the number of individuals over age 80 may increase by 300 million. As humans age, our immune system becomes progressively weaker through a process called immune senescence. This age-related decrease in immune function increases susceptibility to infection and chronic diseases. Sepsis is a leading cause of death worldwide. Over the past two decades, there has been an increased incidence of sepsis which is due, in part, to our aging population …

Genital Chlamydia Infection Is Influenced By The Female Sex Hormones Estrogen And Progesterone In Vivo, Amy Gail Gravitte

Electronic Theses and Dissertations

Chlamydia is the most common bacterial sexually transmitted infection in the United States and worldwide. It often goes unnoticed due to lack of symptoms and left untreated it can ascend the female genital tract to cause sequelae like pelvic inflammatory disease and irreversible tubal infertility. In reproductive-aged women, female sex hormones estrogen (E2) and progesterone (P4) concentrations fluctuate during the menstrual cycle and are influenced by hormonal contraceptives and hormone replacement therapy. E2 and P4 influence genital Chlamydia infection in women and mice, but these multifactorial interactions are not entirely mapped out. The complex interplay of E2 and P4 with …

Synthetic Viral Pyrogen Induces Behavioral Fever In Plethodon Glutinosus Salamanders, Nicholas Britt

Undergraduate Honors Theses

Behavioral fever is an essential coping mechanism across ectothermic phyla to aid in combating pathogenic threats. Ectotherms lack internal temperature regulation associated with fever in endotherms; thus, ectotherms can exhibit a behavioral fever response when immunocompromised to thermoregulate by moving to warmer locations. The salamander order Caudata, tend to be keystone species in their resident ecosystems through their role as secondary consumers of invertebrates to maintain the food chain. With growing interest about ecology and conservation of salamanders as species diversity declines, this study was designed to determine if salamanders use their environment to take advantage of behavioral fever. The …

Immune Activation Induces Telomeric Dna Damage, Reduces Memory Precursors, And Promotes Short-Lived Effector T Cell Differentiation In Chronic Hcv Infection, Lam Nguyen

Electronic Theses and Dissertations

Chronic hepatitis C virus (HCV) infection exhibits persistent high viral load, inducing T cells differentiation and dysfunction in chronically infected individuals. Recent longitude studies in both HCV specific- and bulk T cells reveal that chronic immune stimulation is the driving force for the impaired T cell functions, however, the underlying mechanisms remain elusive. Here, we show that peripheral CD4⁺ T cells from chronically HCV-infected patients exhibit lymphopenia with the reduction of naïve population and expansion of effector memory T cells. CD4⁺ T cells from HCV patient also display elevated activation markers. including HLA-DR, GLUT1, Granzyme B, and short-lived …

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 …

Roles Of Endothelial Cell Heat Shock Protein A12b And Β-Glucan, A Reagent For Trained Immunity In The Regulation Of Inflammation In Sepsis, Fei Tu

Electronic Theses and Dissertations

Sepsis is dysregulated host immune response to infection causing life-threatening organ dysfunction. Endothelial cell dysfunction and uncontrolled inflammatory responses are two contributors for sepsis-induced mortality. The crosstalk between endothelial and immune cells plays a critical role in the pathophysiology of sepsis. Therefore, understanding the mechanism of interaction between endothelial and immune cells will provide novel information to develop therapeutic strategies for sepsis.

Pathogen associated moleculear patterns (PAMPs) and/or damage associated molecular patterns (DAMPs) produced during sepsis, activate endothelial cells to increase the expression of adhesion molecules, attracting immune cell infiltration into the tissues. Uncontrolled inflammatory responses during the early phase …

Role Of Topoisomerase Ii Alpha In Dna Topology And T Cell Responses During Chronic Viral Infections, Stella Chinyere Ogbu

Electronic Theses and Dissertations

The clearance of viruses is largely dependent upon the activation of T cells to generate a robust immune response. However, host responses are suppressed during chronic viral infections. In this thesis, we explored the role of Top2α in DNA topology in individuals with chronic HBV, HCV, and HIV infections. We found that Top2α protein expression and activity were low in T cells derived from chronically virus-infected individuals compared to healthy subjects. Using CD4⁺ T cells treated with Top2α inhibitor or poisoner as a model, we demonstrated that Top2α inhibition disrupts the DNA topology, suppresses DNA repair kinase (ATM), and …

The Distinct Expressions Of Integrins Αdβ2 And Αmβ2 Differently Regulate Macrophage Migration In 3d Matrix In Vitro And In Tissue During Inflammation, Kui Cui

Electronic Theses and Dissertations

Chronic inflammation is an essential mechanism during the development of cardiovascular and metabolic diseases. The outcome of diseases depends on the balance between the migration and accumulation of macrophages in damaged tissues. Macrophage motility is highly regulated by adhesive receptors, integrins. Namely, intermediate expression of integrin supports macrophage migration, while a high integrin density inhibits it. Our studies are focused on evaluation of the contribution of related integrins α_Dβ₂ and α_Mβ₂ to macrophage migration and development of chronic inflammation.

We found that integrin α_Dβ₂ is upregulated on M1-macrophages in vitro and …

Telomeric Dna Damage And Repair Machineries In Hiv Infection, Lam Nguyen

Electronic Theses and Dissertations

In this thesis, we investigated T cell homeostasis and DNA damage repair machineries in HIV infection. We found that the frequencies of CD4T cells were low, which is associated with cell apoptosis in HIV patients compared to healthy subjects. Importantly, these events were closely correlated to the increase in T cell exhaustion, senescence, DNA damage, and telomere attrition. Mechanistically, while the DNA damage sensors Mer11, Rad50, and NBS1 (MRN) complexes remained intact, the ataxia-telangiectasia mutated (ATM) kinase and its downstream checkpoint kinase 2 (CHK2) were significantly inhibited during HIV infection. Additionally, telomeric repeat-binding factor 2 (TRF2) that functions to protect …

Range-Wide Prevalence And Impacts Of Pseudocercosporella Inconspicua On Lilium Grayi And An Assessment Of L. Superbum And L. Michauxii As Reservoirs, Cindy L. Barrett

Electronic Theses and Dissertations

Lilium grayi (Gray’s Lily), a southern Appalachian endemic species, is threatened by a Lilium-specific fungal pathogen, Pseudocercosporella inconspicua. The disease is characterized by tan lesions that can cause early senescence, while also lowering seed production and viability. This project tested for P. inconspicua conidia and accessed health at nine locations. The disease was present and ubiquitous across the range of L. grayi. Through identification of P. inconspicua conidia in the field, L. superbum (Turk’s Cap Lily) was identified as an additional host, while L. michauxii (Michaux’s Lily) was disease-free. However, infection was inducible in both species. With …

Toll Like Receptor 4 Stimulation Increases Scavenger Receptor A Expression On Murine Macrophages, Mackenzie L. Guthrie

Undergraduate Honors Theses

Sepsis is the body’s response to an overwhelming infection and is a serious consequence of critical illness. It can cause tissue damage, organ failure, and death. Sepsis continues to have an unacceptably high mortality rate, due to the lack of effective treatments. Specific therapeutic targets for sepsis remain elusive since the complex functional changes that result in a septic state remain poorly understood. Macrophage Scavenger Receptor A (SRA, CD204) is a surface receptor that binds negatively charged, endogenous and exogenous ligands. We have discovered that SRA plays a significant role in the pathophysiology of sepsis. We have shown that mice …

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 …

Comparison Of Anti-Pneumococcal Functions Of Native And Modified Forms Of C-Reactive Protein, Donald Neba Ngwa

Electronic Theses and Dissertations

The anti-pneumococcal function of native C-reactive protein (CRP) involves its binding to phosphocholine molecules present on Streptococcus pneumoniae and subsequent activation of the complement system. However, when pneumococci recruit complement inhibitory protein factor H on their surface, they escape complement attack. Non-native forms of CRP have been shown to bind immobilized factor H. Accordingly, we hypothesized that modified CRP would bind to factor H on pneumococci, masking its complement inhibitory activity, allowing native CRP to exert its anti-pneumococcal function. As reported previously, native CRP protected mice from lethal pneumococcal infection when injected 30 minutes before infection but not when injected …

Demography And Disease Of The Rare Shrub Buckleya Distichophylla (Santalaceae) In Northeastern Tennessee, William Seth Ratliff

Undergraduate Honors Theses

Piratebush (Buckleya distichophylla (Nutt.) Torr.) is a rare, hemiparasitic shrub with the only extant populations in western North Carolina, northeastern Tennessee, and southwestern Virginia. The preferred natural hosts of piratebush, Carolina and eastern hemlocks, have seen sharp declines over the last decade due to the invasive hemlock woolly adelgid. Virginia pine, another important host of piratebush, is also susceptible to disease, specifically Cronartium appalachianum, a rust fungus for which piratebush is the secondary host. This study described and analyzed current demographic parameters of three Tennessee piratebush populations. Additionally, spatial patterns of disease and demographic characters were analyzed. These …

Regulation Of C-Reactive Protein Gene Expression And Function, Avinash N. Thirumalai

Electronic Theses and Dissertations

Human C-reactive protein (CRP) is the prototypic acute phase protein whose serum concentration increases rapidly during inflammation. CRP is also associated with atherosclerosis; it is deposited at lesion sites where it may interact with modified lipoproteins. There are 2 major questions regarding CRP: 1. How is the serum concentration of CRP regulated? 2. What are the functions of CRP in atherosclerosis?

Our first aim was to determine the role of the constitutively expressed transcription factor Oct-1 in regulating CRP gene expression. We found that Oct-1 overexpression inhibited (IL-6+IL-1β)- induced CRP gene expression; maximal inhibition required the binding of Oct-1 to …

Mechanisms Of The Anti-Pneumococcal Function Of C-Reactive Protein, Toh B. Gang

Electronic Theses and Dissertations

Human C-reactive protein (CRP) increases survival of and decreases bacteremia in mice infected with Streptococcus pneumoniae. Such protection of mice against pneumococcal infection is seen only when CRP is administered into mice 6 hours before to 2 hours after the injection of pneumococci, but not when CRP is given to mice at a later time. Our first aim was to define the mechanism of CRP-mediated initial protection of mice against infection. It was proposed that CRP binds to phosphocholine (PCh) moieties present in the cell wall and activates the complement system on the pneumococcal surface that kills the pathogen. …

Microsporidia Spore Adherence And Host Cell Infection In Vitro, Cory A. Leonard

Electronic Theses and Dissertations

Microsporidia infect invertebrate and vertebrate animals. Human pathogenic microsporidia are associated with severe disease in immunocompromised individuals, and mostly asymptomatic infection in the immunocompetent. Treatment options for microsporidiosis are limited, incompletely effective, and associated with toxicity. Furthermore, microsporidia infection of healthy individuals is poorly understood, and the consequences of asymptomatic infection have not been determined. Little is known about the molecular mechanisms of microsporidia infection, but such information is essential for the development of new therapies. Spores adhere to host cell surfaces in vitro. Our laboratory has focused on determining specific host cell and microsporidia spore surface participants in spore …

T-Cell Dysfunction By Hcv Core Protein Involves Pd-1/Pd-L1 Signaling., Billy Ellis King

Electronic Theses and Dissertations

In 1989 the hepatitis C virus was identified as a significant cause of post-transfusion hepatitis. Nearly two decades later there is still no vaccine, inadequate treatment options, and limited understanding of how the virus establishes chronicity in the majority of the people it infects. Recent reports suggest that the interaction of a negative co-stimulatory pathway mediated by PD-1 and PDL-1 is associated with persistent viral infection. The role, if any, that PD-1/PDL-1 has in HCV infection is unknown. In this study we report that PD-1 is upregulated in T-cells from persons with chronic HCV infection when compared to healthy donors. …

Role Of Mitogen-Activated Kinases In Cd40-Mediated T Cell Activation Of Monocyte/Macrophage And Vascular Smooth Muscle Cell Cytokine/Chemokine Production, Denise M. Milhorn

Electronic Theses and Dissertations

This dissertation represents efforts to determine the functional consequences acquired by vascular smooth muscle cells (SMC) in response to CD40 ligation by activated CD154+ T cells, and to elucidate components of the signaling pathway(s) activated in response to CD40 signaling in both monocytes and SMC. To study the consequences of CD40 stimulation, primary human monocytes and aortic SMC were treated with plasma membranes purified from CD154 + , CD4+ T cells. The results presented in this dissertation demonstrate that SMC, like monocytes/macrophages, are capable of interacting with T cells in a manner that results in reciprocal activation events. SMC were …

Tnf(Alpha)-Dependent And Tnf(Alpha)-Independent Activation Of Macrophage Effector Function, Annette R. Clemons-Miller

Electronic Theses and Dissertations

Tumor necrosis factor α (TNFα) is a pleiotropic cytokine that is predominantly produced by activated macrophages. The effects of TNFα are as diverse as the cells with which it interacts, e.g., stimulating fibroblast growth, exerting cytotoxic/cytostatic; activity against various human and murine cell lines, promoting inflammation through upregulation of endothelial adhesion molecules and IL-8 production. Yet TNFα is best known, and in fact was originally described, for its role in the bacterial-induced hemorrhagic necrosis of tumors and exacerbation of septic shock in which aberrant TNFα production leads to vascular collapse, cachexia, multiple organ failure, and ultimately death in as many …