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Environmental Toxicants And Human B Cells: Insights From Crispr Editing And Genomic Sequencing, Clayton Allex-Buckner Jan 2023

Environmental Toxicants And Human B Cells: Insights From Crispr Editing And Genomic Sequencing, Clayton Allex-Buckner

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The human immunoglobulin heavy chain gene locus (IGH) has two 3 prime regulatory regions (3’IGHRR), each containing three enhancers (hs3, hs1.2, hs4). In animal models, the 3’IghRR regulates IgH expression and class switch recombination (CSR) to different Ig isotypes. The 3’IGHRR hs1.2 enhancer in humans is polymorphic in that an invariant sequence (IS) can be repeated one to four times in tandem. The hs1.2 polymorphism is of interest due to its association with several human autoimmune disorders and its potential sensitivity to exogenous substances such as 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD or dioxin). In mouse models, TCDD inhibits the hs1.2 enhancer and 3’IghRR …


Pushing The Limits: Increasing The Speed And Specificity Of Sars-Cov-2 Testing, Grayson Way Jan 2021

Pushing The Limits: Increasing The Speed And Specificity Of Sars-Cov-2 Testing, Grayson Way

Theses and Dissertations

The prevalence and spread of the current COVID-19 pandemic have highlighted the importance of continual improvements upon current microbiological testing methods. Rapid and accurate testing can help mitigate spread by improving on the time to quarantine and quarantine duration required. As of the writing of this thesis, COVID-19 has been responsible for more than 500,000 deaths in the United States of America, and greater than 2 million deaths globally. The work done in this thesis has shown improvements in the current SARS-CoV-2 testing methodology by reducing the time it takes for patient testing while maintaining accuracy and the sensitivity required …


Investigating Streptococcus Pneumoniae And Adenovirus Co-Infections Of Lung Epithelial Cells, Mark Nicholas Calabro Jan 2021

Investigating Streptococcus Pneumoniae And Adenovirus Co-Infections Of Lung Epithelial Cells, Mark Nicholas Calabro

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Co-infection is common among viruses and bacteria in the human respiratory system. Adenovirus (AdV) and Streptococcus pneumoniae are clinically relevant respiratory pathogens that cause morbidity and mortality in a variety of patient populations with the highest morbidity occurring among immunocompromised individuals, but also prevalent in infants and the elderly. Acute respiratory distress syndrome may become severe in healthy individuals when co-infection with S. pneumoniae and AdV occurs due to synergistic effects of the pathogens on the host. I hypothesized that S. pneumoniae infection decreases AdV transduction of airway epithelia. To test this hypothesis, we utilized the polarized immortalized airway epithelial …


Il-10 And Tgf-Beta Increase Connexin-43 Expression And Membrane Potential Of Hl-1 Cardiomyocytes Coupled With Raw 264.7 Macrophages, Cora B. Cox Jan 2021

Il-10 And Tgf-Beta Increase Connexin-43 Expression And Membrane Potential Of Hl-1 Cardiomyocytes Coupled With Raw 264.7 Macrophages, Cora B. Cox

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Cardiomyocytes and macrophages have been found to interact via connexin-43 hemichannels. The role of connexin-43, however, is not fully understood. This study shows that these interactions aid in increasing the membrane potential of cardiomyocytes allowing contraction of the cells. HL-1 cardiomyocytes and RAW 264.7 macrophages in coculture increased expression of connexin-43 compared to cardiomyocytes alone. Co-cultures also increased the fluorescence of Di-8-ANEPPS potentiometric dye indicating an increase in cardiomyocyte membrane potential. Treatment with IL-10 and TGF-beta further increased connexin-43 expression and membrane potential. Treatment with SOCS3 inhibited the effects of TGF-beta and IL-10 while having no effect on its own. …


Investigating Streptococcus Pneumoniae And Adenovirus Co-Infections Of Lung Epithelial Cells, Mark Nicholas Calabro Jan 2021

Investigating Streptococcus Pneumoniae And Adenovirus Co-Infections Of Lung Epithelial Cells, Mark Nicholas Calabro

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Co-infection is common among viruses and bacteria in the human respiratory system. Adenovirus (AdV) and Streptococcus pneumoniae are clinically relevant respiratory pathogens that cause morbidity and mortality in a variety of patient populations with the highest morbidity occurring among immunocompromised individuals, but also prevalent in infants and the elderly. Acute respiratory distress syndrome may become severe in healthy individuals when co-infection with S. pneumoniae and AdV occurs due to synergistic effects of the pathogens on the host. I hypothesized that S. pneumoniae infection decreases AdV transduction of airway epithelia. To test this hypothesis, we utilized the polarized immortalized airway epithelial …


Development Of In Vitro Models To Study The Rapid Extraintestinal Dissemination Of Salmonella., Adarsh Gopinath May 2020

Development Of In Vitro Models To Study The Rapid Extraintestinal Dissemination Of Salmonella., Adarsh Gopinath

Electronic Theses and Dissertations

Salmonella appears in the bloodstream of mice in as little as 15 minutes after oral inoculation and establishes persistent colonies in the spleen and liver. While its pathway to blood is undetermined, this phenomenon is dependent on the activity of Salmonella pathogenicity island 2 (SPI-2) coded type III secretion system (T3SS) and CD18+ phagocytes. We hypothesize that dendritic cells associated with the basal face of the gut epithelium, that are naturally migratory and known to sample for luminal antigens directly transport Salmonella to the bloodstream. This process comprises of at least two phases, dissociation and reverse transmigration. We define dissociation …


The Persisting Threats Of Cholera: A Cyclical Public Health Problem In Ghana, Rita Laryea Amediavor Jan 2020

The Persisting Threats Of Cholera: A Cyclical Public Health Problem In Ghana, Rita Laryea Amediavor

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The prevalence of communicable diseases continues to be one of the continent's leading causes of deaths. Cholera is a waterborne disease triggered by toxigenic strains of the Gram-negative bacteria Vibrio Cholerae O1 strain and less common O139 strain. with symptoms such as severe acute watery diarrhea and vomiting leading to dehydration, progressing to hypovolemic shock and death if not treated timely due to its short incubation period (Pasetto et al., 2018). West African countries are largely portrayed as endemic to cholera, though the dynamics of outbreaks in these developing countries remain largely uncertain. The purpose of the study is to …


Genetic Study Of Checkpoint Defects Of The Mus81-1 Mutant In The Fission Yeast Schizosaccharomyces Pombe, Darlington Osei Abrefa Jan 2019

Genetic Study Of Checkpoint Defects Of The Mus81-1 Mutant In The Fission Yeast Schizosaccharomyces Pombe, Darlington Osei Abrefa

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In response to various perturbations of DNA replication, the DNA replication checkpoint is activated in eukaryotes to stimulate a cascade of cellular responses that are crucial for maintaining genome stability and cell survival. Defects in the checkpoint pathway result in mutations and genome instability, which is a hallmark for cancers. This study used a genetic approach to identify a mutation in the MMS (methyl methanesulfonate) and UV-sensitive protein Mus81, a DNA repair enzyme that resolves aberrant DNA structures through the homologous recombination pathway. We show that a single missense mutation, identified in fission yeast mus81-1, causes moderate reduction in the …


Enhanced Expression Of Receptor Tyrosine Kinase Mer (Mertk) On Socs3-Treated Polarized Raw 264.7 Anti-Inflammatory M2c Macrophages, Sankhadip Bhadra Jan 2019

Enhanced Expression Of Receptor Tyrosine Kinase Mer (Mertk) On Socs3-Treated Polarized Raw 264.7 Anti-Inflammatory M2c Macrophages, Sankhadip Bhadra

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Macrophages are phagocytic cells located in tissues, organs and even circulated within our body as white blood cells. They are critical in detecting tissue damage and infection. Resident tissue macrophages initiate the signals for inflammation recruiting neutrophils and blood monocytes which mature into macrophages at sites of infection and in the resolution of inflammation. Based on the local cytokine milieu in tissue sites, macrophages may be polarized into pro-inflammatory M1 or anti-inflammatory M2 phenotypes. Receptor tyrosine kinase Mer (MERTK) helps in clearing dead neutrophils and other apoptotic cells from damaged tissue sites preventing chronic inflammation and autoimmune disorders. MERTK aids …


The Effects Of Socs1 And Socs3 Peptide Mimetics On Macrophage Phagocytosis Of Malignant Cells, Tahirah M. Madkhali Jan 2019

The Effects Of Socs1 And Socs3 Peptide Mimetics On Macrophage Phagocytosis Of Malignant Cells, Tahirah M. Madkhali

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Macrophages are essential phagocytic cells involved in both innate and adaptive immune systems and play vital roles in the host defense and inflammation. Macrophages have a remarkably high capacity to clear unnecessary cellular materials in interstitial environment through a process called “phagocytosis”, which is affected by many factors including suppressors of cytokine signaling (SOCS). SOCSs are a group of intracellular proteins that downregulate the cytokine signals involved in various JAK/STAT pathways through a negative feedback loop. This study focuses on investigating the effects of SOCS1 and SOCS3 on the phagocytic ability of RAW 264.7 macrophages polarized into M2a with IL-4/IL-13 …


Six-Nine Months Long Term Culture Of Mouse Bone Marrow Cells Differentiated To Macrophages And Eosinophils, Olena B. Svitlova Jan 2019

Six-Nine Months Long Term Culture Of Mouse Bone Marrow Cells Differentiated To Macrophages And Eosinophils, Olena B. Svitlova

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Mouse models of eosinophil-associated diseases have been used to study the mechanisms of disease pathogenesis. In this study, mouse-derived bone marrow cells were used in long-term (6 and 9 months) cell cultures of differentiated eosinophils and macrophages. IL-5 was used to differentiate the stem cells to eosinophils and GM-CSF was used to propagate macrophages from the bone marrow stem cells. The maximum time period for observing the eosinophil cultures was 252 days which is censurably longer than the 18 days culture period observed by others. The results were assessed by describing the microscopic cell morphology by Wright staining, modified Giemsa …


Virus Production And Cell Viability Of Hsv-1-Infected Murine Keratinocytes (Hel-30) Co-Cultured With Murine Macrophages (Raw 264.7), Barry Graffagna Jan 2018

Virus Production And Cell Viability Of Hsv-1-Infected Murine Keratinocytes (Hel-30) Co-Cultured With Murine Macrophages (Raw 264.7), Barry Graffagna

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Keratinocytes are the most abundant type of cell in the outer layer of skin, the epidermis, and provide barrier against pathogens from invading. However, Herpes Simplex Virus Type 1 (HSV-1) targets these keratinocytes for infection, and later infects neurons to establish lifelong latency. The keratinocytes stimulate the innate immune system to engage and to destroy the virus. Among the cells of the innate immune system to respond to the viral invasion is the macrophage. In this study, RAW 264.7 macrophage and HEL-30 keratinocyte monolayers were challenged in vitro with HSV-1 at a multiplicity of infection (MOI) of 0.1 to investigate …


Effect Of Exposure Of Raw264.7 Macrophages To Salmonella Typhimurium Components On Cell Viability, Cytoskeleton Re-Arrangement And Cytokine Secretion, Khalid Abdullah Alyahya Jan 2017

Effect Of Exposure Of Raw264.7 Macrophages To Salmonella Typhimurium Components On Cell Viability, Cytoskeleton Re-Arrangement And Cytokine Secretion, Khalid Abdullah Alyahya

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Innate immune system plays an important role in individual's protection against pathogens and in activation of adaptive immune system. Utilizing RAW 264.7 murine macrophages as an innate immune response representative in this study, we analyzed the effect of invasive pathogen's components (e.g. flagellin) on the arrangement of macrophage's cytoskeleton, on viability of immune cells and on secretion of pro-inflammatory and anti-inflammatory cytokines and on fluorescence intensity of cytoskeleton after rearrangement. Additionally, we studied the similarity and differences between bacterial (Salmonella typhimurium) and synthetic TLR4 agonist (synthetic lipid-A) on viability, fluorescence intensity, cytokine secretion, and cytoskeleton rearrangements. Similarly, we studied the …


The Impact Of Socs1 And Socs3 Peptide Mimetics On Rho And Cdc42 Proteins Expression, F-Actin Cytoskeleton Rearrangements, And Cytokines Production Of Uninfected And Hsv-1 Infected M1 And M2 Raw 264.7 Murine Macrophages, Maha A. Elwardany Jan 2017

The Impact Of Socs1 And Socs3 Peptide Mimetics On Rho And Cdc42 Proteins Expression, F-Actin Cytoskeleton Rearrangements, And Cytokines Production Of Uninfected And Hsv-1 Infected M1 And M2 Raw 264.7 Murine Macrophages, Maha A. Elwardany

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The immune system plays an essential role in the pathogenesis of HSV-1 during the lytic phase of the disease, orchestrating the inflammatory response, retaining the virus in its latent phase and preventing the recurrence of HSV-1 infection. Macrophages display a vital role in the innate and adaptive immune responses during multiple phases of HSV-1 infection. Polarized macrophages are categorized into two distinct classes with diverse functions. The classically activated M1 can engulf and destroy the microbial agents, produce proinflammatory cytokines, and participate in the pathogenesis of many inflammatory diseases. The alternatively activated M2 induces anti-inflammatory mediators and stimulates tissue remodeling …


Cell Viability, Cytoskeleton Organization And Cytokines Secretion Of Raw 264.7 Macrophages Exposed To Gram-Negative Bacterial Components, Ali Awadh Alshehri Jan 2016

Cell Viability, Cytoskeleton Organization And Cytokines Secretion Of Raw 264.7 Macrophages Exposed To Gram-Negative Bacterial Components, Ali Awadh Alshehri

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Macrophages play an important role in innate immunity by controlling cellular responses. In this study, the effects of gram-negative bacterial components (Flagellin, lipoprotein, lipopolysaccharides (LPS), outer membrane proteins-A (OMP-A) and peptidoglycan) were determined on cell viability, morphology, cytoskeletal filament and cytokines secretion of murine RAW 264.7 macrophages at 24 hours. The effect of LPS, flagellin and peptidoglycan from gram negative bacteria on viability murine RAW 264.7 macrophages were evaluated using different concentrations (1, 5 and 10 µg/ml). Cells stimulated with LPS displayed ~ 2-fold decrease (P=0.001) in cell viability compared to control cells at 24 hours whereas cells stimulated with …


The Expression Of Aryl Hydrocarbon Receptor In Raw 264.7 Macrophages In The Presence Of Socs1 Peptide And Socs3 Peptide Mimetic And Cells Infected With Hsv-1, Maher Salem Alwethaynani Jan 2016

The Expression Of Aryl Hydrocarbon Receptor In Raw 264.7 Macrophages In The Presence Of Socs1 Peptide And Socs3 Peptide Mimetic And Cells Infected With Hsv-1, Maher Salem Alwethaynani

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Macrophages play a crucial role for our immune system and protect our body from infection. Suppressor of cytokine signaling (SOCS) proteins negatively regulate cytokine receptor and TLRs. The aryl hydrocarbon receptor (AhR) also performs an important role in immunity. This study investigated the changes in expression of AhR in RAW 264.7 macrophage cells after the addition of SOCS1 and SOCS3 peptide mimetics and also examined AhR expression in RAW 264.7 macrophage cells before and after the addition of HSV-1 RAW 264.7 murine macrophage cell lines which are from male BALB/c mice were used in this study. The addition of the …


Changes In Cytoskeleton Proteins In Hsv-1 Infection Of J774a.1 Macrophage Phenotype, Riham Abbas Subahi Jan 2016

Changes In Cytoskeleton Proteins In Hsv-1 Infection Of J774a.1 Macrophage Phenotype, Riham Abbas Subahi

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The cell cytoskeleton, a unique intracellular matrix found in all eukaryotes, is composed of three main protein structures, microtubules, microlaments and intermediate laments. The cytoskeleton maintains cell shape and internal structures providing mechanical support that facilitates intracellular transport (Parker et al., 2014). Many viruses such as the herpesviruses use the cytoskeleton system of the cell for infectivity (Henry Sum, M. S. 2015). HSV-1 utilizes the cell cytoskeleton in many steps of its life cycle from entry through assembly to egress (Lyman et al., 2008). During infection, HSV-1 viral proteins cause drastic changes and rearrangement of the cellular actin and cell …


Identification Of Protein-Protein Interactions Of Amyotrophic Lateral Sclerosis Associated Protein Tdp-43, Hanoor Sharma Jan 2016

Identification Of Protein-Protein Interactions Of Amyotrophic Lateral Sclerosis Associated Protein Tdp-43, Hanoor Sharma

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Amyotrophic lateral sclerosis (ALS) is a neurodegenerative disease caused by progressive degeneration of upper and lower motor neurons in the brain and spinal cord. Multiple mutations are found in some of the proteins associated with ALS, including superoxide dismutase (SOD1), fused in sarcoma (FUS) and trans-activation response DNA-binding protein (TDP-43). TDP-43 is a DNA and RNA binding protein, well conserved, and ubiquitously expressed in all tissues. TDP-43 resides in the nucleus and sometimes shuttles between nucleus and cytoplasm. Mutations in TDP-43 leads to mislocalization of TDP-43 to the cytosol where it was ubiqutinated and hyperphosphsorylated, ultimately leading to neuronal cell …


The Impact Of Hsv-1 Infection On Cell Viability, Morphology, And Cd Markers Expression By Unpolarized And Cytokine-Polarized J774a.1 Mouse Macrophages, Sarah Saad Alsharif Jan 2015

The Impact Of Hsv-1 Infection On Cell Viability, Morphology, And Cd Markers Expression By Unpolarized And Cytokine-Polarized J774a.1 Mouse Macrophages, Sarah Saad Alsharif

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Macrophages play an important role in the immune system, particularly in neutralizing pathogens via phagocytosis and the production of multiple cytokines and chemokines that control infection after exposure to specific stimuli. Macrophages exhibit two different phenotypes, M1 and M2. This study evaluated the role of Suppressors of cytokine signaling (SOCS)1 and SOCS3 on Herpes Simplex Virus (HSV-1) infection of polarized macrophages, cell viability, cell morphology, and the expression of cell surface CD markers. I hypothesized that J774A.1 murine macrophages cells in the naive state (M0), and M1 and M2 phenotypes would display differences in CD markers CD80,CD163, and CD200R, cell …


The Use Of Antibody-Coated Latex Beads To Determine Single Positive And Double Positive Mouse Spleen Cells Expressing Cd5 And/Or Cd19 Glycoproteins, Abdulrazzag Abdulaziz Othman Jan 2015

The Use Of Antibody-Coated Latex Beads To Determine Single Positive And Double Positive Mouse Spleen Cells Expressing Cd5 And/Or Cd19 Glycoproteins, Abdulrazzag Abdulaziz Othman

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Flow cytometry is the standard method used to diagnose, stage, and monitor patients' response to the treatment given by counting the numbers of CD5, CD19 and CD5+ CD19+ B lymphocytes. In this study, a comparison was done between numbers of single CD5+, single CD19+ and dual CD5+ CD19+ mouse spleen B lymphocytes using flow cytometry and antibody-latex beads. The bead method involved antibody-coated latex bead and yielded results similar to those of flow cytometry. For cells exhibiting both markers (CD5+ CD19+), the bead method used antibody-coated beads of two different colors yielded similar results to those of flow cytometry results. …


Immunotherapy For Human Breast Cancer, Nasrah Ali Al Kamal Jan 2015

Immunotherapy For Human Breast Cancer, Nasrah Ali Al Kamal

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Al Kamal, Nasrah. M.S. Program of Microbiology and Immunology, Wright State University, 2015.Immunotherapy for Human Breast Cancer. The study focuses on the methodologies that are used in breast cancer therapy. The review finds major evolutions of these methods and the influence they have made on the increased survival rates in cancer patients. There is also a projection of the processes that are involved in the therapy practices and the way the protocols have been improved over time. The various stages of cancer treatment project the various aspects of better performance articulations in the therapy sector. There is also reference to …


Effect Of Herpes Simplex Virus-1 On Macrophage Cd Marker Expression, Hind Obaid Albeshri Jan 2014

Effect Of Herpes Simplex Virus-1 On Macrophage Cd Marker Expression, Hind Obaid Albeshri

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Macrophages are specialized phagocytic cells derived from the peripheral blood mononuclear cells. Macrophages can assume M1 or M2 cellular states upon activation with specific cytokines. Upon activation, macrophages produce either pro- or anti- inflammatory cytokines and thereby perform their functions of antigen engulfment and debris clearance. Macrophages have several cell surface cluster differentiation (CD) markers including CD80, CD163 and CD200R that differentiate M1 macrophages from M2. Downstream signaling and cytokine production varies based on the interaction between the specific CD marker and antigen.

The present study was aimed at analyzing and comparing the effects of HSV-1 infection on un-polarized and …


Comparison Between Flow Cytometry And Bead Method In Counting Cd4 And Cd8 T Lymphocytes In Mouse Spleen Cells Suspension, Abdulrahman Abdalla Allabidi Jan 2014

Comparison Between Flow Cytometry And Bead Method In Counting Cd4 And Cd8 T Lymphocytes In Mouse Spleen Cells Suspension, Abdulrahman Abdalla Allabidi

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The flow cytometry is gold standard method to count CD4, CD8 human T lymphocytes, and calculate CD8 to CD4 ratio in HIV patients peripheral blood to stage them and monitor their response to treatment. In this study, a comparison was made by counting CD4and CD8 mouse spleen T lymphocytes by flow cytometry, and a method involving antibody coated latex beads. The bead method yielded results comparable to those obtained by flow cytometry. These results indicate that antibody coated beads are suitable to determine CD4 and CD8 + T lymphocytes counts in situation where flow cytometry is not readily available.


Novel Approaches For The Eradication Of Hiv Latently Infected Cells, Sally Al Ali Jan 2013

Novel Approaches For The Eradication Of Hiv Latently Infected Cells, Sally Al Ali

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The development of a suitable experimental cell model to study HIV latency in primary cells could have a massive effect on the current approaches to eradicate virus in latently infected cells. The main proposal of this paper is to develop an in vitro HIV cell model that represents HIV latency in vivo, then to create a more effective viral vector in order to target HIV reservoirs. For this goal, a directed evolution method is suggested to be used in order to mutate the AAV cap gene to generate a recombinant AAV vector that is capable of infecting primary resting CD4+ …


Mhc Class I Expression In Murine Fibroblast And Keratinocyte Cell Lines During The First Twenty-Four Hours Of Infection With Herpes Simplex Virus-1 (Hsv-1), Prasanthi Kumchala Jan 2012

Mhc Class I Expression In Murine Fibroblast And Keratinocyte Cell Lines During The First Twenty-Four Hours Of Infection With Herpes Simplex Virus-1 (Hsv-1), Prasanthi Kumchala

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The hypothesis of this study is: HSV-1 infection of murine fibroblasts and keratinocytes inhibits expression of MHC class I molecules during first 24 hours of infection. IFN-γ pretreatment of fibroblasts protected the cells from virus-induced inhibition of MHC class I expression, but did not protect keratinocytes. Herpesviruses are known for their ability to establish persistent infections. Herpesviruses exert many different ways to suppress host defense mechanisms. One such way is by down regulating expression of the major histocompatibility complex I (MHC I) molecules in infected cells. Epidermal cells such as keratinocytes are the major sites for herpes simplex virus type …


Nitric Oxide Production: A Mechanism For Inhibition Of Chlamydia Trachomatis Replication, Bojun Chen Dec 1993

Nitric Oxide Production: A Mechanism For Inhibition Of Chlamydia Trachomatis Replication, Bojun Chen

Electronic Theses and Dissertations

Chlamydia trachomatis (CT) replicates in macrophages, but is inhibited by IFN-$\gamma$ or LPS. IFN-$\gamma$ and/or LPS induced nitrite production in mouse peritoneal macrophages, macrophage cell lines (RAW264.7 and J774A.1) and McCoy cells. Kinetic studies indicated that peak production occurred 48 hours post-treatment. CT infection itself was insufficient to induce nitrite production, but resulted in enhancement of nitrite production in IFN-$\gamma$-treated cells. Treatment with IFN-$\gamma$ or LPS resulted in significant inhibition of CT replication in these cells. Strong correlation between nitrite production and inhibition of CT replication was observed in RAW264.7 and J774A.1 cells (correlation coefficients: $-$0.93 and $-$0.94, p $<$ 0.001). N$\sp{\rm g}$- monomethyl-L-arginine (L-NMMA) specifically inhibited nitrite production and partially reversed inhibition of CT replication in macrophage cell lines. NOS mRNA was measured in RAW264.7 cells by Northern blot and Dot blot hybridization. Strong correlation between NOS mRNA expression and inhibition of CT replication (correlation coefficient: $-$0.97, p $<$ 0.05) was observed. Anti-TNF-$\alpha$ antibody completely neutralized the biological activity of TNF-$\alpha$ secreted by LPS-treated RAW264.7 cells, yet the antibody neither reduced nitrite production nor restored CT replication. Combination of the antibody and L-NMMA significantly enhanced restoration of CT replication. In peritoneal macrophages, inhibition of CT replication induced by IFN-$\gamma$ was partially restored by L-NMMA or anti-TNF-$\alpha$ antibody. In McCoy cells, inhibition of CT replication induced by IFN-$\gamma$ and LPS was not significantly restored by L-NMMA. Great restoration of CT replication by 1 mM L-NMMA was observed in LPS-treated J774A.1 cells (31%), but not in IFN-$\gamma$-treated cells (5%). Our data indicate that (1) NO production is one of the mechanisms for inhibition of CT replication in IFN-$\gamma$-activated peritoneal macrophages and RAW264.7 cells; (2) NO plays a significant role in CT inhibition in LPS-treated macrophage cell lines, but not peritoneal macrophages; (3) TNF-$\alpha$ may be associated with inhibition, but the mechanism(s) may not involve NO production; (4) NO production may not be the mechanism for CT inhibition in McCoy cells treated with IFN-$\gamma$ and LPS.