M.Sc. (Med.), Faculty of Health Sciences, University of the Witwatersrand, 2011 / The cause of cardiac pathology in a significant number of patients with heart failure is unclear. Although chronic inflammatory changes may contribute toward progressive heart failure, whether low-grade chronic systemic inflammation, produced by infective processes or obesity accounts in-part for the development of cardiac dysfunction and heart failure requires further study. In this regard, although lipopolysaccharide (LPS) administration, an inflammatory mediator derived from the walls of gram negative organisms has been shown to produce an increased cardiomyocyte apoptosis, the lowest dose of LPS previously employed is commensurate with doses that produce vascular shock. Hence this does not reflect the impact of inflammatory changes produced by low-grade systemic infections. Moreover, although inflammatory substances have been shown to be released from adipose tissue and obesity is a cause of cardiac dysfunction and heart failure, it is uncertain to what extent inflammatory changes mediate obesity-induced myocardial dysfunction. To clarify the role of LPS and obesity-induced inflammation as potential causes of cardiac damage and dysfunction, in the present dissertation I therefore evaluated the influence of pyrogenic, but non-septic doses of LPS on cardiomyocyte apoptosis and cardiac systolic function in rats and the contribution of inflammation as indexed by circulating high sensitivity C-reactive protein concentrations (hs- CRP) to the relationship between obesity and myocardial systolic function in humans. In normal rats, core body temperature (surgically implanted [in the peritoneal cavity], temperature-sensitive radiotransmitters), cardiomyocyte apoptosis (Terminal Deoxynucleotidyl Transferase Mediated dUTP Nick End Labeling [TUNEL]) staining) and left ventricular (LV) systolic function (two-dimensional directed M-mode echocardiography) were evaluated following two doses of LPS (250 μg/kg), derived from Eschericia coli, delivered 24 hours apart. Cardiac assessments were performed 6 hours after the second LPS dose to ensure that cardiac measurements were obtained at the time of a febrile response, whilst the first LPS dose was employed to ensure that a sufficiently long period had occurred for apoptotic cell death to be iii detected using a TUNEL system. In this study LPS was able to induce a febrile response (p<0.05, n=26, compared to normal circadian rhythm), yet failed to produce an increased cardiomyocyte apoptosis or decreased LV systolic chamber (LV endocardial fractional shortening-FSend) or myocardial (LV midwall fractional shortening-FSmid) function. In 292 randomly selected participants from an urban, developing community not receiving antihypertensive therapy, I also assessed the independent relationship between indices of obesity or hs-CRP and LV FSend and FSmid. In this study indices of adiposity including waist circumference (partial r=0.35, p<0.0001) were independently related to log hs- CRP. Furthermore, waist circumference was independently and inversely associated with FSmid (standardized β-coefficient= -0.19±0.07, p<0.01), but not with FSend. Although log hs- CRP was associated with FSmid on bivariate analysis, no independent relationship between these variables was noted (p=0.21). Furthermore, with the inclusion of both waist circumference and log hs-CRP in the same regression model, waist circumference remained independently associated with FSmid (standardized β-coefficient= -0.18±0.08, p<0.05). In conclusion, the results of the present dissertation do not support a role for pyrogenic, but non-septic doses of LPS in mediating cardiomyocyte apoptosis or dysfunction or a role for low grade inflammation, as indexed by hs-CRP concentrations in mediating obesity-induced myocardial systolic dysfunction.

No description available.

No description available.

Thesis (M.D.) -- University of Pennsylvania, 1811. / Includes bibliographical references. Microform version available in the Readex Early American Imprints series.

Thesis (Doctor of Physic)--Columbia College, New York, 1804. / Running title: On inflammation. Microform version available in the Readex Early American Imprints series.

Thesis (Ph. D.)--University of Chicago, Department of Pathology. / Includes bibliographical references. Also available on the Internet.

Zonula occludens 1 (ZO-1) est une protéine sous-membranaire des jonctions serrées impliquée dans l’organisation structurale des cellules épithéliales. Au cours de la progression tumorale, associée au processus de transition épithélio-mésenchymateuse (TEM), les composants des jonctions intercellulaires sont réorganisés. Notamment, lors de la TEM, la protéine ZO-1 est délocalisée de la membrane vers le cytoplasme et/ou le noyau où elle adopte alors un rôle pro-invasif. Nous avons d’ailleurs montré que ZO-1 cyto-nucléaire régule l’expression de la chimiokine IL-8 dans les cancers broncho-pulmonaires non à petites cellules (CBNPC). Nous nous sommes donc intéressés à l’influence de ZO-1 cyto-nucléaire sur le recrutement des cellules inflammatoires dans les CBNPC. In vitro, le niveau d’expression de ZO-1 module le recrutement de la lignée monocytaire THP-1. Par différentes techniques in vivo, nous avons montré que la surexpression de ZO-1 cyto-nucléaire favorise le recrutement de cellules inflammatoires et immunitaires à des temps précoce et tardif de la réponse immunitaire. En parallèle, la caractérisation de l’infiltrat inflammatoire en fonction de la localisation nucléaire de ZO-1 chez les patients atteints de CBNPC a mis en évidence une corrélation entre l’expression cyto-nucléaire de ZO-1 et la présence de lymphocytes T cytotoxiques CD8+ au sein du microenvironnement tumoral.Ainsi, notre étude révèle un nouveau rôle de la protéine structurale ZO-1. En effet, ZO-1 cyto-nucléaire, associé au processus de TEM, est impliqué dans la mise en place et le développement d’un microenvironnement pro-inflammatoire et/ou pro-immunitairepermissif pour la progression tumorale des CBNPC. / Zonula occludens 1 (ZO-1) is a sub-membrane protein of tight junctions involved in the structural organization of epithelial cells. During tumor progression, associated with the epithelial-mesenchymal transition (EMT) process, intercellular junction components are reorganized. In particular, during EMT, ZO-1 protein is delocalized from the membrane to the cytoplasm and/or the nucleus where it then displays pro-invasive properties. We have shown that ZO-1 cyto-nuclear regulates the expression of chemokine IL-8 in non-small cell lung cancer (NSCLC). We are therefore interested in the influence of cyto-nuclear ZO-1 on the recruitment of inflammatory cells in NSCLC. In vitro, the level of expression of ZO-1 modulates the recruitment of the monocyte-like cell line THP-1. By different in vivo techniques, we have shown that overexpression of cyto-nuclear ZO-1 promotes the recruitment of inflammatory and immune cells at early and late times of the immune response. In parallel, the characterization of the inflammatory infiltrate as a function of the nuclear localization of ZO-1in patients with NSCLC revealed a correlation between the cyto-nuclear expression of ZO-1 and the presence of cytotoxic T lymphocytes CD8+ within the tumor microenvironment.Thus, our study reveals a new role of structural protein ZO-1. Indeed, ZO-1 cyto-nuclear, associated with the EMT process, is involved in the establishment and development of a proinflammatory and/or pro-immune microenvironment permissive for tumor progression of NSCLC.

Thesis (M. Phil.)--University of Hong Kong, 2008. / Also available in print.

La polyarthrite rhumatoïde (PR) est une maladie inflammatoire chronique d’étiologie inconnue. L’inflammation présente dans cette pathologie est fortement dépendante de la cytokine pro-inflammatoire qu’est le TNFα. Cette molécule possède deux récepteurs : le TNFR1 et le TNFR2. Le TNFR1 est un récepteur exprimé à la surface de toutes les cellules. L’activation de sa voie de signalisation déclenche la mort cellulaire et elle est souvent associée à des phénomènes inflammatoires. Le TNFR2, quant à lui, est exprimé à la surface des cellules immunitaires, des cellules endothéliales et des cellules neuronales. L’activation de la signalisation du TNFR2 conduit à la survie et à la prolifération cellulaire. Le TNFR2 est de plus, associé à des mécanismes anti-inflammatoires. Les lymphocytes T régulateurs (Treg), cellules clé dans le contrôle de la réponse immunitaire, sont caractérisés par l’expression du facteur de transcription Forkhead box P3 (FoxP3) et sont défectueux chez des patients atteints de PR. Ces cellules expriment les deux récepteurs du TNFα et sont capables d’inhiber l’action des cellules inflammatoires et particulièrement des T effecteurs par différents mécanismes d’immunosuppression. Les Treg exprimant le TNFR2 représentent la population la plus immunosuppressive actuellement recensée. L’objectif de notre travail a été de mieux comprendre le rôle des Treg exprimant le TNFR2 dans le contrôle de l’inflammation dépendante du TNFα. Tout d’abord, nous avons montré que la signalisation TNFα-TNFR2 sur les Treg augmentait le maintien de l’expression de FoxP3 ainsi que la prolifération de ces cellules. L’expression du TNFR2 est en outre liée à une stabilité accrue de ces cellules. Ces résultats peuvent expliquer le rôle important que pourraient jouer les Treg TNFR2+ dans le contrôle de l’inflammation dépendante du TNFα. Afin de confirmer cette hypothèse, nous avons démontré, dans deux modèles expérimentaux d’inflammation dépendants du TNFα (arthrite et psoriasis), que les Treg TNFR2+ jouaient un rôle prépondérant dans le contrôle de l’inflammation. Enfin, des expériences effectuées chez des patients atteints de PR ont mis en évidence que les traitements anti-TNFα conduisaient à une augmentation de la fréquence des Treg TNFR2+ circulants chez des patients répondeurs. En démontrant le rôle prépondérant des Treg TNFR2+ dans la résolution de l’inflammation, ce travail ouvre la voie vers l’élaboration de thérapies ciblant le système TNFα/TNFR plus spécifiques pour le traitement de la PR et d’autres pathologies dépendantes du TNF. / Rheumatoid arthritis (RA) is a chronic inflammatory disease with unknown etiology. In this pathology, inflammation is mainly dependent on the pro-inflammatory cytokine TNFα. This molecule acts through two receptors: TNFR1 and TNFR2. TNFR1 is expressed on almost all cell types. Activation of this pathway mainly leads to cell death and is often associated with pro-inflammatory response. In contrast, TNFR2 is expressed on immune, epithelial and neuronal cells. Activation of TNFR2 signaling triggers cellular survival and cell proliferation. Furthermore, TNFR2 pathway is associated with anti-inflammatory mechanisms. Regulatory T cells (Treg) play a pivotal role in the control of inflammation and are defective in RA. They are characterized by the expression of transcriptional factor Forkhead box P3 (FoxP3). Tregs express both TNFα receptors and are able to inhibit inflammatory cells, specifically effector T cells using various immunosuppressive mechanisms. Treg expressing TNFR2 have been identified as the most suppressive Treg population. The aim of this study was to elucidate the role of TNFR2+ Tregs in TNFα mediated - inflammation by. Firstly, we have shown that TNFα-TNFR2 signaling on Tregs increased their proliferation and helped to maintain FoxP3 expression. Moreover, TNFR2 expression was associated with increased Treg stability. These results could explain the potential role of TNFR2+ Tregs in control of TNFα mediated - inflammation. To confirm this hypothesis, we demonstrated, in two models of inflammation mediated by TNFα (arthritis and psoriasis), that TNFR2+ Tregs play a major role in the control of inflammation. Finally, our experiments in RA patients highlighted that anti-TNFα treatments increased circulating TNFR2+ Treg frequency in responder RA patients. By demonstrating the major role of TNFR2+ Tregs in resolution of inflammation, our work paves the way for therapies targeting more specifically TNFα/TNFR system to cure RA and others TNFα - mediated pathologies.

A Thesis submitted to the Faculty of Health Sciences, University of the Witwatersrand, Johannesburg, in fulfilment of the requirements for the degree of Doctor of Philosophy (PhD), 2017 / Asthma is the most prevalent chronic respiratory disease worldwide, with South Africa having the fourth highest asthma mortality rate in the world (1.5 per 100,000 people) and the fifth highest asthma mortality among five to thirty-five year old asthmatics (18.5 per 100,000 asthmatics). Current guidelines recommend that the achievement of ‘asthma control’ may still be plagued with persistent airway inflammation despite normalisation of spirometric parameters and control of asthmatic symptoms. This may result in structural damage with airway remodelling, fibrosis and progressive loss of lung capacity over time. Assessment of inflammation,‘Inflammometry’ is now increasingly used to titrate therapeutic interventions and achieve better asthma control. The current study aims to identify simple, objective, non invasive and reproducible biomarkers for airway inflammation; that would allow documentation of the presence or absence of airway inflammation in individual asthmatic patients. The availability of such tests may allow titration of therapeutic interventions to an outcome parameter that is a true reflection of the state of inflammation of the airways. This was a prospective, single centre, cross-sectional study of patients with confirmed asthma attending a dedicated specialist asthma clinic at the Charlotte Maxeke Johannesburg Academic Hospital Asthma Clinic. Patients attending the clinic were identified from patient records and those who met the inclusion and exclusion criteria, were selected for the study. The level of asthma control of each patient was determined using the Asthma Control Questionnaire (ACQ). Patients undertook the Asthma Control Test (ACT), had an independent assessment of their asthma control as well as performed lung function tests in a dedicated lung function laboratory. Blood and exhaled breath samples from patients were analysed for inflammatory biomarkers. Optimisation experiments were performed to establish a protocol for the measurement of serum leukotrienes in the asthmatic patient. For the statistical analyses, patients were characterised into asthma control groups as defined by the ACQ. The current study found that the ACQ and the ACT, as well as the ACQ and an independent physician’s assessment of the level of asthma control were in synchrony. Baseline FEF 25-75 levels, expressed as percentage of predicted, were low in the totally controlled, well-controlled and uncontrolled groups of asthmatic patients with medians of 35.7%, 27.3% and 17.3% respectively. The FEF 25-75 values in the three groups demonstrated an absolute post bronchodilator reversibility of 32%, 27% and 31% respectively. These findings confirmed the presence of bronchial airway hyper-reactivity (BAH), and suggest probable remodelling in the small airways. Impulse oscillometry (IOS) had a greater value in differentiating small airway resistance in the controlled when compared to the uncontrolled adult asthmatic patient. Biomarker assessments found that CRP, IL-2 and RANTES were significantly higher in the uncontrolled group when compared with the controlled group of asthmatic patients (p = 0.03, p = 0.02 and p = 0.03 respectively). Of the three serum leukotrienes measured (i.e. LTB4, LTC4 and LTE4), LTE4 levels were significantly higher in the totally controlled group compared to the uncontrolled and well-controlled groups (p = 0.007 and p = 0.006 respectively). Therefore, an elevated LTE4 coupled to a suppressed level of RANTES in the same patient may identify a different asthma phenotype. This could provide opportunities for identifying asthma phenotypes and using biomarkers in assessing asthma control. The study also found that TGFβ1 and TGFβ2 levels were significantly higher in patients using high-dose inhaled corticosteroids (ICS) (dose category as defined by the Global Initiative for Asthma (GINA)), compared to those patients not using high-dose ICS (p = 0.01 and p = 0.001 respectively). By comparison, TGFβ1 and TGFβ2 levels were significantly lower in the patients using moderate-dose ICS (dose category as defined by GINA), compared to those not using moderate-doses of ICS (p = 0.02 and p = 0.001 respectively). These findings suggest that airway inflammation is modulated by the upregulation of Treg cells as TGFβ is produced by Treg cells. It is also possible that Treg cells under the influence of elevated IL-2 levels inhibited the expression of the other Th1 as well as Th2 cytokines measured. Therefore, an elevated TGFβ level coupled with an elevated IL-2 level in the same patient may also identify a different asthma phenotype. Collectively, biomarker assessments may prove useful in assessing asthma control. Such assessments may require individualisation for different asthma endotypes and phenotypes, possibly even using biomarker profiling using multiple biomarkers for future patient care considering the heterogeneity of inflammation in asthma. / XL2019