Streptococcus pneumoniae is a significant human pathogen and the leading cause of community-acquired pneumonia and acute otitis media. One of the primary defense mechanisms of the human immune system against pneumococcal infection involves granule-mediated killing of bacterial cells by neutrophils. While this mechanism has previously been shown to kill about half of pneumococci in vitro, we hypothesized that some pneumococcal strains have evolved to be more resistant to this granule-mediated killing. Clinical isolates demonstrated a varying range of sensitivity to neutrophil granules. Additionally, we established that the absence of the capsule may affect sensitivity as unencapsulated isolates showed a higher average survival than encapsulated isolates. Finally, pneumococcal surface protease HtrA was found to potentially serve as a protective factor as many knockouts were more sensitive than the wildtypes, recombinant HtrA protected wildtype TIGR4, and a resistant isolate showed higher htrA expression levels than sensitive isolates.

No description available.

No description available.

The mechanism responsible for the killing of tumor cells after injection of mice with a mixture of tumor cells and Propionibacterium acnes were investigated. Tumor cells were injected intramuscularly into Balb/c mice either alone or together with P. acnes vaccine. The tumor cells were then removed from the injection site 12 hours after injection, and transferred into fresh mice. Tumor cells from control animals given tumor cells only caused tumors when transferred into fresh mice 12 hours after injection whereas tumor cells from animals given both tumor cells and vaccine did not develop tumors in the fresh nice. ELISA tests were done to estimate the number of tumor cells in the lesions. In control animals given 10⁵ tumor cells the estimated numbers dropped to 10³ cells at 24 hours, but thereafter rose steadily. Palpable tumors were present 7-10 days later. In animals given 10⁵ tumor cells + 500 ug of P. acnes vaccine, estimated tumor cell numbers fell steadily, and could not be detected after 2 days. Palpable tumors never developed in these animals. These results indicate that tumor cells are killed, or rendered nontumorigenic, during the first 12 hours after co-injection into mice with P. acnes Histological studies showed that injection of P. acnes vaccine, with or without tumor cells, induced large numbers of polymorphonuclear leukocytes (PMNs) at 12 hours. To determine the role of PMNs in the killing of tumor cells, tumor cells were incubated with supernatant obtained from the phagocytosis mixture of PHNs and P. genes. After a 2- hr. incubation, the tumor cells were washed and injected into fresh mice. No tumors developed, indicating that a product of the phagocytosis of P. acnes by PMNs played a role in the killing of tumor cells. Bacterial vaccines such as P. freudenreichii, which are poorly protective against tuner cells, produced phagocytosis supernatants which were unable to kill tumor cells. Various oxygen radical scavengers/inhibitors were used to test their effect on the toxicity of the supernatant on tumor cells and chinese hamster ovary cells. Both azide and catalase rendered the supernatant nontoxigenic, suggesting that H₂O₂, produced by PHNs during phagocytosis of P. acnes, is responsible for the killing of tumor cells. However, the addition of catalase 30 minutes after the start of phagocytosis had no effect on the toxicity of the supernatant, suggesting that H₂O₂ is converted to other toxic radicals during the course of phagocytosis of P. acnes by PMNs. The oxygen consumption levels of PHNs during phagocytosis of P. acnes or other bacterial vaccines was measured and found to be similar regardless of the antitumor ability of the vaccine used. This suggests that the difference in the ability of various vaccines to protect mice against tumors may be in the production of a particular oxygen radical by PMNs during phagocytosis, and not in the production of different quantities of the same radicals. / Master of Science / incomplete_metadata

published_or_final_version / Paediatrics / Master / Master of Philosophy

Fong, Oi Ning. / Thesis (M.Phil.)--Chinese University of Hong Kong, 2009. / Includes bibliographical references (leaves 170-195). / Abstracts in English and Chinese. / Abstract --- p.i / Acknowledgements --- p.vi / Contents --- p.viii / List of Abbreviations --- p.xii / Chapter CHAPTER ONE --- Introduction --- p.1 / Chapter 1.1 --- Bacterial Infection in Neonates --- p.1 / Chapter 1.2 --- Gram-positive and Gram-negative Bacterial Cell Wall --- p.3 / Chapter 1.2.1 --- Gram-negative Bacterial Cell Wall Component - Lipopolysaccharide --- p.3 / Chapter 1.2.2 --- Gram-positive Bacterial Cell Wall Component - Peptidoglycan --- p.4 / Chapter 1.3 --- Differential Host Response against Gram-specific Bacterial Infection --- p.6 / Chapter 1.4 --- Role of Neutrophils in Host Defense against Bacterial Infection --- p.8 / Chapter 1.4.1 --- Recognition of Bacterial Components --- p.9 / Chapter 1.4.2 --- Neutrophil Functions --- p.10 / Chapter 1.5 --- Expression Profiling of Activated Neonatal Neutrophils --- p.15 / Chapter CHAPTER TWO --- Objectives --- p.26 / Chapter CHAPTER THREE --- Materials and Methodology --- p.27 / Chapter 3.1 --- Overview of the Experimental Procedure --- p.27 / Chapter 3.2 --- Cord Blood Sample Collection --- p.28 / Chapter 3.3 --- Cord Blood Neutrophil Isolation --- p.30 / Chapter 3.3.1 --- Isolation of Neutrophils --- p.30 / Chapter 3.3.2 --- Analysis of Neutrophil Purity by Flow Cytometry --- p.31 / Chapter 3.3.3 --- Cell Viability Test by Trypan Blue Exclusion Assay --- p.31 / Chapter 3.4 --- In Vitro Stimulation of Neutrophils by LPS or PGN --- p.33 / Chapter 3.5 --- Total RNA and Protein Isolation --- p.34 / Chapter 3.5.1 --- Total RNA Isolation --- p.34 / Chapter 3.5.2 --- Protein Isolation --- p.35 / Chapter 3.6 --- Preparation of Total RNA Samples for Expression Profiling and Quantitative Real Time Polymerase Chain Reaction (qPCR) --- p.37 / Chapter 3.6.1 --- DNase Treatment --- p.37 / Chapter 3.6.2 --- Total RNA Cleanup --- p.37 / Chapter 3.6.3 --- Purity Assessment of the Purified Total RNA Sample --- p.38 / Chapter 3.6.4 --- Integrity Assessment of the Purified Total RNA Sample --- p.39 / Chapter 3.6.5 --- Assessment of Tumor Necrosis Factor Alpha (TNF-α) mRNA Expression Level in Neutrophils --- p.42 / Chapter 3.7 --- Determination of the PGN Concentration for Neutrophil Activation --- p.43 / Chapter 3.8 --- "Expression Profiling of the LPS, PGN Stimulated or Unstimulated CB Neutrophils" --- p.44 / Chapter 3.8.1 --- cRNA Preparation and Array Hybridization --- p.44 / Chapter 3.8.2 --- Expression Profiling Data Analysis --- p.46 / Chapter 3.9 --- Validation of Candidate Genes Using qPCR --- p.48 / Chapter 3.10 --- Gram-Negative Bacterial Endotoxin Assay --- p.50 / Chapter CHAPTER FOUR --- LPS Stimulation Induced Transcriptional Changes in Cord Blood Neutrophils --- p.61 / Chapter 4.1 --- Result --- p.61 / Chapter 4.1.1 --- Gene Expression Profile of CB Neutrophils in Response to LPS Stimulation --- p.61 / Chapter 4.1.1.1 --- Up-regulated Genes in LPS-stimulated CB Neutrophils --- p.61 / Chapter 4.1.1.2 --- Down-regulated Genes in LPS-stimulated CB Neutrophils --- p.62 / Chapter 4.1.1.3 --- Network Analysis of Genes Induced by LPS Stimulation --- p.63 / Chapter 4.2 --- Discussion --- p.64 / Chapter 4.2.1 --- Robust Transcriptional Response in CB Neutrophils --- p.64 / Chapter 4.2.2 --- LPS Modulated Transcriptional Responses --- p.64 / Chapter 4.2.2.1 --- LPS-induced NF-kB Pathway --- p.64 / Chapter 4.2.2.2 --- LPS-induced Expression of Various Transcription Factors --- p.66 / Chapter 4.2.2.3 --- LPS-induced Regulation of Apoptosis --- p.67 / Chapter CHAPTER FIVE --- PGN Stimulation Induced Transcriptional Changes in Cord Blood Neutrophils --- p.83 / Chapter 5.1 --- Result --- p.83 / Chapter 5.1.1 --- Gene Expression Profile of PGN-stimulated CB Neutrophils --- p.83 / Chapter 5.1.2 --- Up-regulated Genes in PGN-stimulated CB Neutrophils --- p.83 / Chapter 5.1.3 --- Down-regulated Genes in PGN-stimulated CB Neutrophils --- p.84 / Chapter 5.1.4 --- Network Analysis of Genes Induced by PGN Stimulation --- p.84 / Chapter 5.2 --- Discussion --- p.86 / Chapter 5.2.1 --- Robust Transcriptional Response in CB Neutrophils --- p.86 / Chapter 5.2.2 --- PGN Modulated Transcriptional Responses --- p.86 / Chapter 5.2.2.1 --- PGN-induced NF-kB Pathway --- p.86 / Chapter 5.2.2.2 --- Possible Role of STAT3 in PGN-stimulated CB Neutrophil --- p.89 / Chapter 5.2.2.3 --- Possible Role of c-Jun in PGN-stimulated CB Neutrophil --- p.90 / Chapter CHAPTER SIX --- Comparison and Validation of LPS- and PGN-activated Transcriptomes in Cord Blood Neutrophils --- p.106 / Chapter 6.1 --- Result --- p.106 / Chapter 6.1.1 --- Comparison of the Transcriptional Changes of LPS- and PGN- stimulated CB Neutrophils --- p.106 / Chapter 6.1.2 --- Common Transcriptional Changes of LPS- and PGN-Stimulated CB Neutrophils --- p.106 / Chapter 6.1.2.1 --- Commonly Up-regulated Genes in LPS- and PGN- Stimulated Neutrophils --- p.107 / Chapter 6.1.2.2 --- Commonly Down-regulated Genes in LPS- and PGN- Stimulated Neutrophils --- p.107 / Chapter 6.1.2.3 --- Network Analysis of Genes Commonly Regulated by LPS and PGN --- p.108 / Chapter 6.1.3 --- Differential Transcriptional Changes of LPS- and PGN- Stimulated CB Neutrophils --- p.108 / Chapter 6.1.4 --- Real Time qPCR Validation of the Expression Levels of Selected Genes --- p.109 / Chapter 6.1.5 --- Expression Changes of the Confirmed Target Genes in Response to High-dose LPS Stimulation --- p.110 / Chapter 6.2 --- Discussion --- p.111 / Chapter 6.2.1 --- Activation of NF-kB and Related Genes by Both LPS- and PGN-stimulation in CB Neutrophils --- p.111 / Chapter 6.2.2 --- Commonly Expressed Genes - Transcription Factor MAFF --- p.112 / Chapter 6.2.3 --- Commonly Expressed Genes - Novel Gene G0S2 --- p.113 / Chapter 6.2.4 --- Suspected Commonly Expressed Genes - Transcription Factor NR4A3 --- p.114 / Chapter 6.2.5 --- Differentially Expressed Genes - Heat Shock Proteins --- p.115 / Chapter 6.2.6 --- Differentially Expressed Genes 226}0ؤ AP-1 Transcription Factor Complex --- p.118 / Chapter 6.2.7 --- Other Differentially Expressed Genes --- p.121 / Chapter CHAPTER SEVEN --- General Discussion and Conclusion --- p.164 / Bibliography --- p.168

Diss. (sammanfattning) Linköping : Univ., 2003. / Härtill 4 uppsatser.

Diss. (sammanfattning) Stockholm : Karol. inst., 2004. / Härtill 4 uppsatser.

Thesis (doctoral)--University of Göteborg, 1997. / Added t.p. with thesis statement inserted.

Thesis (M.S.)--West Virginia University, 2003. / Title from document title page. Document formatted into pages; contains ix, 75 p. : ill. (some col.) Vita. Includes abstract. Includes bibliographical reference.