Thesis (M.Med.Sc.)--University of Hong Kong, 2009. / Includes bibliographical references (p. 72-83).

Thesis (Ph. D.)--University of Chicago, Committee on Immunology, 2002. / Includes bibliographical references. Also available on the Internet.

Thesis (M. Phil.)--University of Hong Kong, 2010. / Includes bibliographical references (leaves 90-116). Also available online.

Thesis (M. Phil.)--University of Hong Kong, 2010. / Includes bibliographical references (leaves 90-116). Also available in print.

Quercetin is a flavonoid found in commonly consumed fruits and vegetables that has exhibited powerful antioxidant and anti-inflammatory properties in rodents and in vitro. In humans, the effect of quercetin on exercise induced oxidative stress and inflammation is still equivocal and need to be further investigated. A powerful antioxidant such as quercetin may inhibit the high levels of oxidative stress and inflammation associated with the high volume and intensity of exercise training seen with endurance-trained individuals. PURPOSE: To determine the effect of 28 days of daily quercetin supplementation on intensive endurance exercise induced cytokine response. vi METHODS: Thirteen trained cyclists (VO2peak 58.8 ± 3.9 ml/kg/min) were recruited for this study from the University of Texas at Austin and the local Austin, Texas community and participated in this placebo controlled, randomized, crossover designed study. After initial assessment of baseline data (VO2peak, lactate threshold, and two familiarization time trials), participants began daily supplementation with either an antioxidant supplement containing vitamins and quercetin (Q-VIT: 1000mg quercetin, 820mg Vitamin C, 40mg Vitamin B3) or the same vitamin supplement without quercetin (VIT: 820mg Vitamin C, 40mg Vitamin B3). A simulated time trial using an electromagnetically braked cycle ergometer in which subjects had to complete a set amount of work (kJ) as fast as possible was performed on the last day of supplementation. Blood collection was performed at three time points of the time trial days: before exercise (PRE), after warm up (MIN 20), and immediately after time trial exercise (POST). Measured plasma markers were Interleukin-6 (IL-6), C-Reactive Protein (CRP), and Interleukin-10 (IL-10). RESULTS: Q-VIT compared to VIT had no effect on pre, min 20 and post exercise plasma IL-6, CRP, and IL-10 ( P= 0.7, 0.08, and 0.32 respectively). However there was a trend that Q-VIT lowered plasma CRP compare to VIT ( P = 0.08). CONCLUSION: Chronic supplementation for 28 days with a quercetin based antioxidant supplement did not affect plasma cytokine before during or after exercise. The results of the current study suggest that chronic supplementation with quercetin does not influence plasma cytokine and exercise induced cytokine response in endurance-trained athletes. / text

Cyclic proliferation and differentiation occur in the human endometrium in each menstrual cycle. Aside from the precise regulation of estrogen and progesterone, the physiology of the human endometrium is also tightly regulated by cytokines. It is therefore not surprising that imbalance of cytokine expression could be observed when women suffer from gynecological disease such as endometriosis, a common gynecological disease associated with altered cytokine profile and chronic inflammatory response. Although the etiology of endometriosis is not yet well elucidated, a commonly accepted Sampson theory suggests reflux of endometrial tissue to other parts of the reproductive tract would be one of the causes. As recent findings demonstrate the presence of somatic stem cells residing in human endometrium and endometriotic cyst, the hypothesis of the thesis was that cytokines confer a regulatory role in the proliferation and self-renewal of the endometrial and endometriotic stem/progenitor cells. In this project the following objectives were studied: 1) To investigate the effect of cytokines interleukin (IL) - 1β, IL-8, IL-10, IL-13, tumor necrosis factor (TNF) – α and interferon (IFN) – γ on the clonogenic ability of endometrial and endometriotic colony forming units (CFUs); 2) To determine the effect of IL-1β and IL-13 on the self-renewal and proliferative potential of the CFUs; 3) To elucidate the expression patterns of IL-1 and IL-13 receptors in endometrial and endometriotic sections and CFUs. Clonogenic analysis of endometrial and endometriotic stem cells showed an increase in clonogenicity in endometrial epithelial cells when treated with IL-1β. Treatment of IL-13 led to a drop in clonogenicity in endometrial epithelial and stromal cells while IFN-γ treatment resulted in a decreased clonogenicity in endometrial epithelial, stromal and endometriotic stromal cells. Other cytokines (IL-8, IL-10, TNF-α) displayed no effect on the clonogenicity of endometrial and endometriotic cells. Functional study by replating IL-1β and IL-13 treated endometrial and endometriotic CFUs revealed that these cytokines did not affect the self-renewal ability of endometrial and endometriotic CFUs. The proliferative potential of CFUs was determined by total cell output assay. The results suggested that IL-1β up-regulated the proliferative potential of the endometriotic stromal CFUs but not the endometrial epithelial and stromal CFUs, while IL-13 did not alter the proliferative potentials of endometrial and endometriotic CFUs. Comparative analysis on the effect of IL-1β and IL-13 between endometrial and endometriotic stromal CFUs demonstrated that IL-1β would preferentially promote the proliferative potential of ectopic stromal CFUs while IL-13 selectively increases that of normal stromal CFUs. Receptor expression analysis by immunostaining demonstrated the presence of IL-1 receptor and IL-13 receptors protein in the glandular epithelium of endometrial tissue. Their expression was more diffuse in the endometriotic tissues. Using reverse transcription–polymerase chain reaction, IL-1RI, IL-13Rα1, IL-13Rα2 mRNA was detected in endometrial and endometriotic stromal cells, while only in endometrial epithelial cells express IL-1RII mRNA as well as IL-1RI, IL-13RαI and IL-13Rα2 mRNA. The present study suggests a role of cytokines on endometrial and endometriotic stem/progenitor cells and further investigation of actions of cytokines would be constructive on the development of endometriosis. / published_or_final_version / Obstetrics and Gynaecology / Master / Master of Philosophy

Chronic obstructive pulmonary disease (COPD) is a progressive disease and characterized by persistent airflow limitation. Pathophysiologically it involves many components, including oxidative stress and inflammation of the airways and lungs. Although the primary cause of COPD is smoking, acute exacerbation due to infections can accelerate disease progression, which is a significant cause of morbidity, mortality and burden on healthcare costs. One-half of all acute exacerbations of COPD are associated with bacterial infection, with non-typeable Hemophilus influenzae being the most common pathogen. Staphylococcus pneumonia, one of the most common Gram-positive bacterial pathogens, is also involved in airway infections, either primary or subsequent to viral diseases. To COPD patients the common respiratory pathogens include Gram-negative and Gram-positive bacterial species. Lipopolysaccharide (LPS), a major component of the outer membrane of all Gram-negative bacteria, which is the predominant inducer of inflammatory responses, has been widely studied. On the other hand, less is known about Gram-positive bacteria, which do not contain LPS but express lipoteichoic acid (LTA) as an important proinflammatory constituent in their cell wall. Serotonin (5-hydroxytryptamine, 5-HT) is a neurotransmitter that plays an important role in regulating pulmonary function and pathogenesis of inflammation. In this study, we hypothesize that the serotoninergic system may be involved in LPS- and LTA-induced inflammation in COPD. Since monocyte recruitment to lung is a key step in COPD, this study aims to investigate the effects of LPS or LTA alone and in combination of 5-HT pretreatment on the release of pro-inflammatory cytokines in undifferentiated (i.e. monocytes) and differentiated THP-1 cells (i.e. macrophages). LPS, LTA or 5-HT alone induced the release of interleukin-8 (IL-8) and monocyte chemoattractant protein-1 (MCP-1) in both monocytes and macrophages. Our findings also showed that 5-HT pretreatment suppressed the LPS-induced IL-8 and MCP-1 release, suggesting that 5-HT might act as an anti-inflammatory mediator. On the other hand, 5-HT pretreatment enhanced the LTA-induced IL-8 and MCP-1 release, indicating that 5-HT might also act as a pro-inflammatory mediator. These results demonstrate that 5-HT may be involved in the differential modulation of inflammatory processes during Gram-negative or Gram-positive infections in COPD. / published_or_final_version / Medicine / Master / Master of Medical Sciences

published_or_final_version / Pathology / Master / Master of Philosophy

Entamoeba histolytica is a protozoan parasite and the causative agent of amoebiasis. While infection is associated with suppression of cell-mediated, immunity, drug-cured patients are resistant to reinvasion by amoebae. Macrophages are the principal effector cells in host defence against E. histolytica via production of nitric oxide which is cytotoxic for the parasite. The objective of this study was to determine the T cell cytokine responses associated with host defence against E. histolytica . A mixed Th1/Th2 (Th0) response predominated at days 5--10 of amoebic liver abscess development in gerbils, as indicated by spleen and hepatic lymph node cell IL-2 (Th1 marker) and IL-4 (Th2 marker) production. However, T cell responses were profoundly suppressed at day 20 of infection. Serum collected at day 20, but not at other times, markedly suppressed T cell proliferative responses by inhibiting IL-2 production. A switch to a Th1 response occurred after day 20 of infection. Following drug-abbreviation of infection at day 20, animals were completely resistant to challenge infection in the liver and demonstrated a Th1 response. The Gal-lectin 170-kDa heavy subunit of E. histolytica is a protective antigen in gerbils and a potential subunit vaccine candidate. We determined which region of the Gal-lectin stimulates IL-12 production, as IL-12 is key to inducing Th1 cytokine responses. Native Gal-lectin plus interferon-gamma stimulated IL-12 p40 and p35 gene transcription and IL-12 p70 protein production in human macrophages. Using a panel of anti-170-kDa subunit monoclonal antibodies in inhibition studies, aa 596--998 was identified as the IL-12-inducing domain. These results suggest that this portion of the Gal-lectin has potential for use as a subunit vaccine to induce Th1-mediated immunity against E. histolytica .

The IL-6 family of cytokines includes IL-6, ciliary neurotrophic factor (CNTF), leukemia inhibitory factor (LIF), oncostatin M (OSM), cardiotrophin-1, and IL-11. Functioning in a pleiotropic and redundant manner, these cytokines play an important role in the regulation of complex cellular processes such as gene activation, proliferation and differentiation, by signalling through homo- or heterodimers of gp130. This thesis describes the characterization of the interactions between the cytokine oncostatin M (OSM) and the cytokine-binding homology region (CHR) of its receptor gp130. Three forms of OSM were expressed, the native form and two truncated forms. Both mutations were obtained by C-terminal truncation. The first, OSM185, has an 11 amino residue deletion and the second, OSM187, has a 9-residue deletion. A variety of biophysical techniques were applied to investigate the complex. Analytical ultra-centrifugation (AUC), surface Plasma Resonance (SPR) and isothermal titration calorimetry (ITC) studies indicated that the purified proteins were stable in monomeric form and can form a 1:1 complex with affinity in the 0.1 μM range. One of the C-terminal truncated forms, the 187 residues version, showed higher stability than the native OSM (196 residues), but still demonstrated similar binding properties to the gp130-CHR. A ¹⁵N and ¹³C double-labelled OSM187 sample was produced for NMR studies. Due to the size of these two proteins, OSM187 (21.5 kDa) and gp130-CHR (25.2 kDa), the NMR studies of the complex are challenging. Applying the TROSY technique, data were obtained from the labelled OSM187 when it is in complex with gp130-CHR. The data could be compared with the free form OSM187 and several shifted peaks were detected. The binding site mapping work has just begun. The characterized binding properties and methods established for sample preparation provide a solid starting point for later studies. The thesis also contains an exploratory study of interactions between interleukin-2 (IL-2) and the IL-2 receptor β chain.