Medical Immunology Commons^™

Mechanism Of Chimeric Vaccine Mediated Immune Suppression Of Human Dendritic Cells, Jacques Christian Mbongue

Loma Linda University Electronic Theses, Dissertations & Projects

Type 1 diabetes mellitus is a chronic inflammatory disease in which insulin producing β-cells of the pancreatic islets are killed by autoreactive cells of the immune system in response to a loss of tolerance. Dendritic cells (DC) interact predominantly with naïve T cells to regulate the delicate balance between immunity and tolerance required to maintain immunological homeostasis. In this dissertation, immature human dendritic cells (iDC) were inoculated with a chimeric fusion protein vaccine containing the pancreatic β-cell auto-antigen proinsulin linked to a mucosal adjuvant the cholera toxin B subunit (CTB-INS). Proteomic analysis of vaccine inoculated DCs revealed strong up-regulation of …

Needle In The Haystack: Combining Intravital Imaging And Mathematical Modeling To Understand How Vaccine-Induced T Cells Find Malaria-Infected Cells In Murine Livers, Vitaly V. Ganusov, Ian Cockburn, Reka Kelemen

Biology and Medicine Through Mathematics Conference

No abstract provided.

Hiv-1 Genetic Variation Resulting In The Development Of New Quasispecies Continues To Be Encountered In The Peripheral Blood Of Well-Suppressed Patients., Will Dampier, Michael R Nonnemacher, Joshua Mell, Joshua Earl, Garth D Ehrlich, Vanessa Pirrone, Benjamas Aiamkitsumrit, Wen Zhong, Katherine Kercher, Shendra Passic, Jean W Williams, Jeffrey M Jacobson, Brian Wigdahl

Kimmel Cancer Center Faculty Papers

As a result of antiretroviral therapeutic strategies, human immunodeficiency virus type 1 (HIV-1) infection has become a long-term clinically manageable chronic disease for many infected individuals. However, despite this progress in therapeutic control, including undetectable viral loads and CD4+ T-cell counts in the normal range, viral mutations continue to accumulate in the peripheral blood compartment over time, indicating either low level reactivation and/or replication. Using patients from the Drexel Medicine CNS AIDS Research and Eradication Study (CARES) Cohort, whom have been sampled longitudinally for more than 7 years, genetic change was modeled against to the dominant integrated proviral quasispecies with …

Diffuse Traumatic Brain Injury Induces Prolonged Immune Sysregulation And Potentiates Hyperalgesia Following A Peripheral Immune Challenge, Rachel K. Rowe, Gavin I. Ellis, Jordan L. Harrison, Adam D. Bachstetter, Gregory F. Corder, Linda J. Van Eldik, Bradley K. Taylor, Francesc Marti, Jonathan Lifshitz

Microbiology, Immunology, and Molecular Genetics Faculty Publications

Background: Nociceptive and neuropathic pain occurs as part of the disease process after traumatic brain injury (TBI) in humans. Central and peripheral inflammation, a major secondary injury process initiated by the traumatic brain injury event, has been implicated in the potentiation of peripheral nociceptive pain. We hypothesized that the inflammatory response to diffuse traumatic brain injury potentiates persistent pain through prolonged immune dysregulation.

Results: To test this, adult, male C57BL/6 mice were subjected to midline fluid percussion brain injury or to sham procedure. One cohort of mice was analyzed for inflammation-related cytokine levels in cortical biopsies and serum along an …

Signaling In Effector Lymphocytes: Insights Toward Safer Immunotherapy, Kamalakannan Rajasekaran, Matthew J. Riese, Sridhar Rao, Li Wang, Monica Thakar, Charles Sentman, Subramaniam Malarkannan

Dartmouth Scholarship

Receptors on T and NK cells systematically propagate highly complex signaling cascades that direct immune effector functions, leading to protective immunity. While extensive studies have delineated hundreds of signaling events that take place upon receptor engagement, the precise molecular mechanism that differentially regulates the induction or repression of a unique effector function is yet to be fully defined. Such knowledge can potentiate the tailoring of signal transductions and transform cancer immunotherapies. Targeted manipulations of signaling cascades can augment one effector function such as antitumor cytotoxicity while contain the overt generation of pro-inflammatory cytokines that contribute to treatment-related toxicity such as …

Genetic Predisposition And M1 Macrophage Polarization Created By Elastin-Derived Peptides Drive Abdominal Aortic Aneurysm Formation, Matthew A. Dale

Theses & Dissertations

Abdominal aortic aneurysm (AAA) is a dynamic vascular disease characterized by inflammatory cell invasion and extracellular matrix (ECM) degradation. Evidence has demonstrated a profound influence of genetic background on AAA formation. The work presented herein discusses two studies: the first demonstrates how genetic components can enhance the susceptibility to AAA formation and the second demonstrates how ECM degradation enhances AAA progression by influencing inflammatory cell phenotypes. An understanding of the pathways involved in AAA pathogenesis can help not only to identify potential patients at risk of AAA development, a heritable disease in which the incriminating component has yet to be …

Ifn-Γ Receptor And Stat1 Signaling In B Cells Are Central To Spontaneous Germinal Center Formation And Autoimmunity., Phillip P. Domeier, Sathi Babu Chodisetti, Chetna Soni, Stephanie L. Schell, Melinda J. Elias, Eric B. Wong, Timothy K. Cooper, Daisuke Kitamura, Ziaur S.M. Rahman

Department of Microbiology and Immunology Faculty Papers

Spontaneously developed germinal centers (GCs [Spt-GCs]) harbor autoreactive B cells that generate somatically mutated and class-switched pathogenic autoantibodies (auto-Abs) to promote autoimmunity. However, the mechanisms that regulate Spt-GC development are not clear. In this study, we report that B cell-intrinsic IFN-γ receptor (IFN-γR) and STAT1 signaling are required for Spt-GC and follicular T helper cell (Tfh cell) development. We further demonstrate that IFN-γR and STAT1 signaling control Spt-GC and Tfh cell formation by driving T-bet expression and IFN-γ production by B cells. Global or B cell-specific IFN-γR deficiency in autoimmune B6.Sle1b mice leads to significantly reduced Spt-GC and Tfh cell …

A Conserved Dna Repeat Promotes Selection Of A Diverse Repertoire Of Trypanosoma Brucei Surface Antigens From The Genomic Archive., Galadriel Hovel-Miner, Monica R. Mugnier, Benjamin Goldwater, George A. M. Cross, F. Nina Papavasiliou

Microbiology, Immunology, and Tropical Medicine Faculty Publications

African trypanosomes are mammalian pathogens that must regularly change their protein coat to survive in the host bloodstream. Chronic trypanosome infections are potentiated by their ability to access a deep genomic repertoire of Variant Surface Glycoprotein (VSG) genes and switch from the expression of one VSG to another. Switching VSG expression is largely based in DNA recombination events that result in chromosome translocations between an acceptor site, which houses the actively transcribed VSG, and a donor gene, drawn from an archive of more than 2,000 silent VSGs. One element implicated in these duplicative gene conversion events is a DNA repeat …

A Conserved Dna Repeat Promotes Selection Of A Diverse Repertoire Of Trypanosoma Brucei Surface Antigens From The Genomic Archive., Galadriel Hovel-Miner, Monica R Mugnier, Benjamin Goldwater, George A M Cross, F Nina Papavasiliou

Microbiology, Immunology, and Tropical Medicine Faculty Publications

African trypanosomes are mammalian pathogens that must regularly change their protein coat to survive in the host bloodstream. Chronic trypanosome infections are potentiated by their ability to access a deep genomic repertoire of Variant Surface Glycoprotein (VSG) genes and switch from the expression of one VSG to another. Switching VSG expression is largely based in DNA recombination events that result in chromosome translocations between an acceptor site, which houses the actively transcribed VSG, and a donor gene, drawn from an archive of more than 2,000 silent VSGs. One element implicated in these duplicative gene conversion events is a DNA repeat …

Human Neonatal Fc Receptor Mediates Transcytosis Of Immunoglobulin-G-Bound Ovalbumin, Farah Gazi

MCB Articles

Introduction: There is increasing evidence that allergies, like many other chronic diseases of childhood, may have origins during the prenatal period. It is also known that mothers, have a stronger influence than fathers, on the development of allergic disease in their children. While the mechanisms responsible for this maternal influence are not known, studies have indicated the possibility of transplacental allergen transfer via immunoglobulin G (IgG) containing immune complexes.

Objective: In this study, we investigated the ability of the neonatal Fc receptor for IgG transport (FcRn) to bind and transport the model allergen ovalbumin in the form of an IgG-ovalbumin …

Regulation Of Irf-3-Dependent Innate Immune Signaling Pathway By The Plpro Domain Of Non-Structural Protein 3 (Nsp3) Of Severe Acute Respiratory Syndrome (Sars) Coronavirus, Sandra Nicole Lester

Theses and Dissertations (ETD)

The induction of Type I Interferons (IFNs) is a powerful and rapid innate defense mechanism against viral infection, and many viruses have developed elaborate strategies to overcome the antiviral effects of IFN, ensuring their survival and replication. Severe acute respiratory syndrome coronavirus (SARS-CoV) is a highly pathogenic virus that causes severe lung disease in humans and is associated with high mortality rates. SARS-CoV, like all other successful viruses, encode proteins that counteract the innate immune response. A number of reports have indicated the papain-like protease (PLpro) domain of SARS-CoV Non-Structural Protein 3 (NSP3) as a powerful interferon antagonist, by suppressing …

Friendly Fire: Biological Functions And Consequences Of Chromosomal Targeting By Crispr-Cas Systems, Gary E. Heussler, George A. O'Toole

Dartmouth Scholarship

Clustered regularly interspaced short palindromic repeat (CRISPR)-associated (Cas) systems in bacteria and archaea target foreign elements, such as bacteriophages and conjugative plasmids, through the incorporation of short sequences (termed spacers) from the foreign element into the CRISPR array, thereby allowing sequence-specific targeting of the invader. Thus, CRISPR-Cas systems are typically considered a microbial adaptive immune system. While many of these incorporated spacers match targets on bacteriophages and plasmids, a noticeable number are derived from chromosomal DNA. While usually lethal to the self-targeting bacteria, in certain circumstances, these self-targeting spacers can have profound effects in regard to microbial biology, including functions …

The Role Of Drak2 In T Cell Function And Autoimmunity, Tarsha L. Harris

Theses and Dissertations (ETD)

The immune system utilizes many regulatory mechanisms to limit immune responses and ensure that immune cells target foreign pathogens and not healthy cells of the body. However, some immune cells can escape these checkpoints and attack the body’s healthy cells, leading to tissue destruction and devastating autoimmune disorders. For example, multiple sclerosis (MS) occurs when immune cells attack the myelin sheath surrounding neurons of the central nervous system (CNS). Likewise, the destruction of pancreatic islet cells by dysregulated immune cells leads to type 1 diabetes (T1D). Remarkably, there are more than 80 types of autoimmune diseases. An estimated 50 million …

Interaction Between Two E3 Ligases, Nedd8ylated Cullin And Hhari, Kheewoong Baek

Theses and Dissertations (ETD)

RBR (RING1-in between RING-RING2) is a special type of E3 ubiquitin ligase containing three zinc-binding RING (Really Interesting New Gene) domains, while adopting mechanisms of HECT (Homologous to E6-AP Carboxyl Terminus) for substrate ubiquitination. Most well known RBRs include Parkin and HOIP, which are associated with Parkinson’s disease and innate immune deficiency. However, it is not well known how the RBR proteins gain activity, as they are known to be autoinhibited. Here I show that a specific F430A, E431A, E503A triple mutation of RBR protein HHARI (Human homologue of Ariadne) and its interaction with NEDD8ylated cullin RING ligase can both …

Pten Signaling In Regulatory T Cells And Inflammatory Disease, Sharad Krishna Shrestha

Theses and Dissertations (ETD)

Regulatory T (Treg) cells suppress CD4+ T cell responses during homeostasis and inflammation to prevent autoimmunity and other immune disorders. Although the transcriptional and epigenetic programs impacting Treg cell function have been extensively studied, the signaling and metabolic pathways underlying Treg stability and function are not fully understood. In this study, we determined the role of the phosphatase PTEN in Treg cells. We found that specific depletion of PTEN in Treg cells results in excessive TH1 and T follicular helper cells (TFH) responses, associated with elevated germinal center (GC) B cells and spontaneous development of autoimmune and lymphoproliferative disease in …

Impact Of Epigallocatechin-3-Gallate (Egcg), A Broad-Spectrum Anti-Inflammatory, In Controlling Intestinal Factors Contributing To Inflammatory Bowel Disease., Gerald Wayne Dryden, Jr.

Electronic Theses and Dissertations

This dissertation explores the role of epigallocatechin-3-gallate (EGCG), as a potential treatment for patients with inflammatory bowel disease (IBD). IBD is a common disorder that causes a great deal of suffering. Our understanding of the etiologies, pathogenic mechanisms, and treatment targets continues to evolve. Many new therapeutic targets are making their way through the pharmaceutical pipelines. However, not all patients benefit from these therapies. EGCG has long been studied as an anti-cancer agent. Most of our understanding of this compound comes from the oncologic literature. As the pathways of oncology and inflammation converge, new lessons can be taken from the …

Porphyromonas Gingivalis Gingipains Induce A Pro-Inflammatory Extracellular Microenvironment : The Role Of Par-2 And Fibronectin., Jeffrey S. Marschall

Electronic Theses and Dissertations

Periodontitis is a chronic inflammatory disease that is characterized by severe tissue destruction of the gingiva and other tooth supporting structures; if left untreated, tooth loss and disintegration of the alveolar bone occurs. This chronic inflammatory state has been linked to other systemic diseases such as cardiovascular disease, diabetes, rheumatoid arthritis, and Alzheimer’s disease. Porphyromonas gingivalis is the major pathogenic microbe in periodontitis. The main virulence factors of P. gingivalis are the Arg-aa and Lys-aa gingipains, which are proteolytic enzymes implicated in a plethora of activities that allow P. gingivalis to subvert the human immune system in the oral cavity …

Vaccination Of Gerbils With Bm-103 And Bm-Ral-2 Concurrently Or As A Fusion Protein Confers Consistent And Improved Protection Against Brugia Malayi Infection., Sridhar Arumugam, Junfei Wei, Zhuyun Liu, David Abraham, Aaron Bell, Maria Elena Bottazzi, Peter J Hotez, Bin Zhan, Sara Lustigman, Thomas R Klei

Department of Microbiology and Immunology Faculty Papers

BACKGROUND: The Brugia malayi Bm-103 and Bm-RAL-2 proteins are orthologous to Onchocerca volvulus Ov-103 and Ov-RAL-2, and which were selected as the best candidates for the development of an O. volvulus vaccine. The B. malayi gerbil model was used to confirm the efficacy of these Ov vaccine candidates on adult worms and to determine whether their combination is more efficacious.

METHODOLOGY AND PRINCIPLE FINDINGS: Vaccine efficacy of recombinant Bm-103 and Bm-RAL-2 administered individually, concurrently or as a fusion protein were tested in gerbils using alum as adjuvant. Vaccination with Bm-103 resulted in worm reductions of 39%, 34% and 22% on …

A Subset Of Latency-Reversing Agents Expose Hiv-Infected Resting Cd4+ T-Cells To Recognition By Cytotoxic T-Lymphocytes., R. Brad Jones, Stefanie Mueller, Rachel O'Connor, Katherine Rimpel, Derek D Sloan, Allison S. Thomas, Sara Karandish, Szu-Han Huang, +13 More

Microbiology, Immunology, and Tropical Medicine Faculty Publications

Resting CD4+ T-cells harboring inducible HIV proviruses are a critical reservoir in antiretroviral therapy (ART)-treated subjects. These cells express little to no viral protein, and thus neither die by viral cytopathic effects, nor are efficiently cleared by immune effectors. Elimination of this reservoir is theoretically possible by combining latency-reversing agents (LRAs) with immune effectors, such as CD8+ T-cells. However, the relative efficacy of different LRAs in sensitizing latently-infected cells for recognition by HIV-specific CD8+ T-cells has not been determined. To address this, we developed an assay that utilizes HIV-specific CD8+ T-cell clones as biosensors for HIV antigen expression. By testing …

Dietary Nitrate In Decreased Blood Pressure In Obstructive Sleep Apnoea Syndrome: A Series Of N-Of-1trials, Conor Kerley, Liam Cormican, Eamon Dolan

Articles

Obstructive sleep apnoea syndrome (OSAS) is a consequence of repetitive oropharyngeal airway narrowing/closure during sleep resulting in chronic intermittent hypoxaemia [1]. OSAS is regarded as an independent risk factor for hypertension (HTN) development [2] and is associated with decreased cerebral blood flow [3], leading to daytime neuropsychological sequelae [1]. Blood pressure (BP) follows a circadian rhythm termed dipping and the absence of nocturnal BP dipping is associated with target-organ damage, cerebrovascular disease, myocardial remodelling and increased cardiovascular events/mortality [4]. Abnormal BP in OSAS typically manifests as reduced nocturnal BP dipping [5]. Although continuous positive airway pressure therapy (CPAP) represents the …

Dissecting The Novel Roles Of Trim56 In Antiviral Innate Immunity, Baoming Liu

Theses and Dissertations (ETD)

The tripartite motif-containing (TRIM) proteins have emerged as a new class of host antiviral restriction factors, with several demonstrating roles in regulating innate antiviral responses. Of >70 known TRIMs, TRIM56 inhibits replication of bovine viral diarrhea virus, a ruminant pestivirus of the family Flaviviridae, but has no appreciable effect on VSV, a rhabdovirus. We have also shown that TRIM56 forms a complex with the Toll-like receptor-3 (TLR3) adaptor, TRIF, via its C-terminal residues 621-750, and augments TLR3-mediated interferon (IFN) induction and establishment of an antiviral state. Yet, TRIM56’s antiviral spectrum and the precise underlying mechanisms by which TRIM56 executes …

Treatment And Prevention Of Human Rotavirus (Hrv) In Developing Countries: The Potential Of Avian Immunoglobulin Y, Christa Brown

Senior Honors Theses

Rotavirus gastroenteritis is a leading cause of childhood mortality, killing ~1400 children younger than five daily, primarily through severe diarrheal dehydration. Eighty-five percent of this mortality occurs in developing countries where rotavirus vaccines are not widely implemented and are only partially effective. In those countries, it has proven difficult to implement the recommended supportive therapies like oral rehydration therapy (ORT) on a wide scale due to lack of both medical infrastructure and private economic investment combined with cultural bias against ORT. IgY targeting human rotavirus (anti-HRV IgY) shows potential as a passive immunotherapy that reduces rotavirus-associated morbidity and mortality, augments …

The Homophilic Domain – An Immunological Archetype, Heinz Kohler, Jagadeesh Bayry, Srinivas V. Kaveri

Microbiology, Immunology, and Molecular Genetics Faculty Publications

The homophilic potential emerges as an important biological principle to boost the potency of immunoglobulins. Since homophilic antibodies in human and mouse sera exist prior environmental exposure, they are part of the natural antibody repertoire. Nevertheless, hemophilic properties are also identified in induced antibody repertoire. The use of homophilicity of antibodies in the adaptive immunity signifies an archetypic antibody structure. The unique feature of homophilicity in the antibody repertoire also highlights an important mechanism to boost the antibody potency to protect against infection and atherosclerosis as well to treat cancer patients.

Effects Of A Mindfulness-Based Weight Loss Intervention In Adults With Obesity: A Randomized Clinical Trial., Jennifer Daubenmier, Patricia J Moran, Jean Kristeller, Michael Acree, Peter Bacchetti, Margaret E Kemeny, Douglas F. Nixon, +11 Additional Authors

Microbiology, Immunology, and Tropical Medicine Faculty Publications

OBJECTIVE: To determine whether adding mindfulness-based eating and stress management practices to a diet-exercise program improves weight loss and metabolic syndrome components.

METHODS: In this study 194 adults with obesity were randomized to a 5.5-month program with or without mindfulness training and identical diet-exercise guidelines. Intention-to-treat analyses with multiple imputation were used for missing data. The primary outcome was 18-month weight change.

RESULTS: Estimated effects comparing the mindfulness to control arm favored the mindfulness arm in (a) weight loss at 12 months, -1.9 kg (95% CI: -4.5, 0.8; P = 0.17), and 18 months, -1.7 kg (95% CI: -4.7, 1.2; …

Lipidomic Dataset Of Plasma From Patients Infected With Wild Type And Nef-Deficient Hiv-1 Strain., Peter Meikle, Hann Low, Melissa J Churchill, Michael Bukrinsky, Dmitri Sviridov

Microbiology, Immunology, and Tropical Medicine Faculty Publications

Previous in vitro and in vivo studies demonstrated that HIV protein nef plays a key role in impairing cellular and systemic cholesterol metabolism in HIV disease, but clinical support for these findings is lacking. Here we present the data of comparative lipidomic analysis (330 lipid species) of plasma samples from HIV-negative subjects, patients infected with WT HIV-1 strain and patients infected with nef-deficient strain of HIV-1. We determine which effects of HIV on plasma lipidome are explained by the presence of nef. The data can be used to evaluate cardiovascular risk in HIV disease and to assess the role of …

Micro-Rna And Mrna Profiles Associated With Ectopic Germinal Center Formation In Thymus Samples Of Patients With Autoimmune Myas, Manjistha Sengupta, Bi-Dar Wang, Norman H. Lee, Gary Cutter, Linda Louise Kusner, Henry J. Kaminski

GW Research Days 2016 - 2020

Myasthenia gravis (MG) is an autoimmune neuromuscular disorder caused by antibodies directed against proteins present at the post-synaptic surface of neuromuscular junction (NMJ). A characteristic pathology of patients with early onset MG is thymic hyperplasia with ectopic germinal centers (GC). However, mechanisms that trigger and maintain thymic hyperplasia are poorly characterized. Micro-RNAs (miRNA) are small, non-coding RNAs that are increasingly appreciated to be involved in the pathology of several autoimmune diseases. In order to determine the central mechanisms involved in the pathology, thymus samples from MG patients were assessed by histology and grouped based on appearance of GC compared to …

Herpes Simplex Virus And Interferon Signaling Induce Novel Autophagic Clusters In Sensory Neurons, Sarah Katzenell, David A. Leib

Dartmouth Scholarship

Herpes simplex virus 1 (HSV-1) establishes lifelong infection in the neurons of trigeminal ganglia (TG), cycling between productive infection and latency. Neuronal antiviral responses are driven by type I interferon (IFN) and are crucial to controlling HSV-1 virulence. Autophagy also plays a role in this neuronal antiviral response, but the mechanism remains obscure. In this study, HSV-1 infection of murine TG neurons triggered unusual clusters of autophagosomes, predominantly in neurons lacking detectable HSV-1 antigen. Treatment of neurons with IFN-β induced a similar response, and cluster formation by infection or IFN treatment was dependent upon an intact IFN-signaling pathway. The autophagic …

Challenges Of Adoptive (T-)Cell Transfer Immunotherapy For Cancer, Aaron Volk

Biology: Student Scholarship & Creative Works

Background and significance: The rebirth of the theory of immunosurveillance in 2001 rejuvenated interest in anticancer immunotherapies. In particular, T-cell-based therapies have garnered substantial interest due to the robustness and tumor antigen-specific cytotoxicity of T-cell anticancer immune responses.

Hypothesis: The efficacy of adoptive cell transfer (ACT) T-cell immunotherapy could significantly improve and gain widespread approval if future innovations in ACT-based approaches account for the pro- and antitumoral properties of non-CD8⁺ lineages of effector T-cells, evasion of T-cell antitumor immunity, and tumor-induced suppression of antitumor immunity.

Problem Analysis: Despite numerous reports of highly successful ACT-based clinical trials, no such therapy …

The Significance Of A Common Idiotype (1f7) On Antibodies Against Human Immune Deficiency Virus Type 1 And Hepatitis C Virus, Sybille Muller, Matthew S. Parsons, Heinz Kohler, Michael Grant

Microbiology, Immunology, and Molecular Genetics Faculty Publications

In this review, we trace the concept and potential functional role of regulatory idiotypes in the immune response to human immunodeficiency virus type 1 (HIV-1), simian immunodeficiency virus, and hepatitis C virus (HCV). A major idiotype involved in these viral infections is recognized and defined by a murine monoclonal antibody (1F7). Antibodies expressing the idiotype defined by 1F7 are dominant in HIV-1 infection and are also found on many broadly neutralizing antibodies against HIV-1. This regulatory idiotypic axis offers opportunities for exploitation in vaccine development for HIV-1, HCV, and other chronic viral infections.

The Gras Sensor In Staphylococcus Aureus Mediates Resistance To Host Defense Peptides Differing In Mechanisms Of Action, Siyang Chaili, Ambrose L. L. Cheung, Arnold S. Bayer, Yan Q. Xiong, Alan Waring, Guido Memmi, Niles Donegan

Dartmouth Scholarship

Staphylococcus aureus uses the two-component regulatory system GraRS to sense and respond to host defense peptides (HDPs). However, the mechanistic impact of GraS or its extracellular sensing loop (EL) on HDP resistance is essentially unexplored. Strains with null mutations in the GraS holoprotein (ΔgraS) or its EL (ΔEL) were compared for mechanisms of resistance to HDPs of relevant immune sources: neutrophil α-defensin (human neutrophil peptide 1 [hNP-1]), cutaneous β-defensin (human β-defensin 2 [hBD-2]), or the platelet kinocidin congener RP-1. Actions studied by flow cytometry included energetics (ENR); membrane permeabilization (PRM); annexin V binding (ANX), and cell death protease activation (CDP). …