No description available.

Females are relatively protected from inflammatory diseases, particularly conditions that are characterised by excessive tissue infiltration of neutrophils (PMNs), such as ischaemia/reperfusion (I/R) injury. Therefore, understanding sex-differences is very important particularly for appropriate treatment of inflammatory disorders in men and women. Unfortunately, efforts to exploit sex-differences therapeutically have been unsuccessful since the precise mechanisms that confer the protective advantage in females over males are unclear. Many fundamental aspects of the nature of sex-differences have not been investigated, particularly in the regulation of PMN mobilisation from the bone marrow during acute inflammation. The aim of this thesis is to determine the nature and mechanism of leukocyte activation and recruitment in males and females, particularly in I/R. This thesis demonstrates for the first time that regulation of PMN mobilisation during acute inflammation is distinct in females. In comparison to males, females demonstrate reduced expression of mediators that cause the release of PMNs, including GCSF, CXCR2 and CXCL5, and increased expression of CXCR4 and CXCL12, which mediate PMN retention in the bone marrow. Reduced granulopoiesis, PMN mobilisation and recruitment into tissues in response to inflammogens protect females from collateral damage incurred by PMN-derived mediators that contribute to tissue injury and loss of function. This thesis has also revealed a novel, and possibly predominant, role for the ELR+ CXC chemokine CXCL5 in mobilisation of tissue-damaging PMNs from the bone marrow, whereby CXCL5 production, PMN mobilisation and tissue infiltration was profoundly greater in males during acute inflammation. CXCL5 appears to stimulate PMN mobilisation by 1) upregulating CXCR2 v expression on bone marrow cells and simultaneously downregulating CXCR4 expression; 2) inducing its own expression; 3) stimulating GCSF expression; and 4) increasing PMN expression of β2 integrin. Thus, the thesis proposes that reduced CXCL5 expression, and increased CXCR4/CXCL12 expression, in females during acute inflammation may be a novel mechanism underlying the protection against tissue injury. The fact that these sex-differences were apparent in different species (rat, mouse), tissues (mesenteric, lung, kidney, heart), in response to different stimuli (mesenteric, renal, myocardial I/R and carrageenan-induced pleurisy) and shown both in vivo and in vitro, suggests that this is a fundamental, and more generalised, phenomenon in males and females following acute inflammation. The inherent differences between the sexes have important clinical implications in that they demonstrate the need of considering sex-differences in research. This thesis demonstrates that sex-differences must be taken into account when developing such therapies for specific inflammatory diseases such as I/R injury as there are major differences in the temporal profile of chemokines and the extent of PMN infiltration.

Introduction – Severe pulmonary bacterial infections are frequently complicated by systemic hypoxaemia and, in the context of acute respiratory distress syndrome (ARDS), inappropriately prolonged neutrophilic inflammation. This combination of acute hypoxaemia and persistent inflammatory response carries significant morbidity and mortality. However, patients with chronic lung disease function in the community with chronic systemic hypoxaemia and bacterial colonisation with much lower acute mortality. The HIF/PHD pathway tightly regulates neutrophilic responses to hypoxia and bacteria. Here, using acute bacterial pneumonia models, I have dissected the differences in innate immune responses to infection in acute hypoxia and following exposure to hypoxia prior to infection (‘preconditioning’). Methods – C57BL/6 mice were housed in room air or ‘preconditioned’ by exposure to 10% ambient hypoxia for seven days. They were then instilled with intratracheal Streptococcus pneumoniae (1x104 or 1x107 cfu to assess macrophage and neutrophil function respectively) under recovery anaesthesia and housed in normoxia (21% O2) or hypoxia (10% O2). At pre-determined time-points, the animals were assessed clinically for sickness and rectal temperature. Blood, bronchoalveolar lavage and tissues were taken for analysis. Transcriptome analysis by RNA-sequencing and functional glycolysis by Seahorse was performed on blood leucocytes. Results – Concurrent exposure to hypoxia and infection resulted in neutrophil-mediated morbidity and mortality. Acute hypoxia caused rapid utilisation of glucose, glycogen and fat stores resulting in systemic hypoglycaemia and death. Preconditioning with exposure to hypoxia prior to infection completely protected the host against hypoxia-induced morbidity and mortality by suppressing leucocyte glycolysis, through suppression of HIF1α, and resultant rescue from the negative energy state and cardiovascular compromise. Conclusion – Hypoxia preconditions the innate immune response by suppression of HIF1α and glycolysis in leucocytes, thereby protecting against acute hypoxia-induced mortality outcomes in acute bacterial pulmonary infection.

The Genus Trichinella is currently thought to consist of 8 seperate species. Several methods have been used to help differentiate these. In this study the ability of three of these species, T. spiralis, T. pseudospiralis, and T. sp. 3 to idependantly infect MRL++ mice was compared at 5, 7, 11, 18 and 20 days post infection ( dpi) with the hope of discovering new distinguishing characteristics. Of interest was the development of inflammation through the accumulation of neutrophils associated with larvae of Trichinella in mouse skeletal muscle. This was evaluated with routine histological stains, endogenous peroxidase staining and immunohistochemical staining specific for neutrophil myeloperoxidase. The inflammatory response in skeletal muscle varied considerably among these three species with neutrophil accumulation being very heavy in the later stages of T. spiralis infection , mild in T. sp. 3 and virtually nonexistant in T. pseudospiralis infections. Also, the appearance of neutrophils was closely correlated with the development of a nurse cell or cyst in the larvae that develop these structures. In T. pseudospiralis where cyst formation is absent, there consistently was a lesser degree of inflammation. These results suggest a possible role of neutrophils involved in inflammation or the process of inflammation itself in the production of nurse cell formation as well as confirming previously described antiinflammatory capabilities of T. sp. 3 and T. pseudospiralis.

Humans are continuously exposed to airborne spores of the saprophytic fungus Aspergillus fumigatus. In healthy individuals, local pulmonary host defence mechanisms can efficiently eliminate the fungus without any overt symptoms. In contrast, A. fumigatus causes devastating infections in immunocompromised patients. However, local host immune responses against A. fumigatus lung infections in immunocompromised conditions have remained largely elusive. Given the dynamic changes in immune cell subsets within tissues upon immunosuppressive therapy, we dissected the spatiotemporal pulmonary immune response after A. fumigatus infection to reveal basic immunological events that fail to effectively control the invasive fungal disease. In different immunocompromised murine models, myeloid but not lymphoid cells were strongly recruited upon infection. Notably, neutrophils and macrophages were recruited to infected lungs in different immunosuppressed regimens. Other myeloid cells, particularly dendritic cells and monocytes were only recruited in the corticosteroid model after infection. Lymphoid cells, particularly CD4+ or CD8+ T-cells and NK cells were highly reduced upon immunosuppression and were not recruited after A. fumigatus infection. Importantly, adoptive CD11b+ myeloid cell transfer rescued immunosuppressed mice from lethal A. fumigatus infection. These findings illustrate that CD11b+ myeloid cells are critical for anti-A. fumigatus defence under immunocompromised conditions. Despite improved antifungal agents, invasive A. fumigatus lung infections cause a high rate morbidity and mortality in neutropenic patients. Granulocyte transfusions have been tested as an alternative therapy for the management of high-risk neutropenic patients with invasive A. fumigatus infections. To increase the granulocyte yield for transfusion, donors are treated with corticosteroids. Yet, the efficacy of granulocyte transfusion and the functional defence mechanisms of granulocytes collected from corticosteroid treated donors remain largely elusive. We aimed to assess the efficacy of granulocyte transfusion and functional defence mechanisms of corticosteroid treated granulocytes using mouse models. In this thesis, we show that transfusion of granulocytes from corticosteroid treated mice did not protect cyclophosphamide immunosuppressed mice against lethal A. fumigatus infection in contrast to granulocytes from untreated mice. Upon infection, increased levels of inflammatory cytokines helped to recruit granulocytes to the lungs without any recruitment defects in corticosteroid treated and infected mice or in cyclophosphamide immunosuppressed and infected mice that have received the granulocytes from corticosteroid treated mice. However, corticosteroid treated human or mouse neutrophils failed to form neutrophil extracellular traps (NETs) in in vitro and in vivo conditions. Further, corticosteroid treated granulocytes exhibited impaired ROS production against A. fumigatus. Notably, corticosteroids impaired the β-glucan receptor Dectin-1 (CLEC7A) on mouse and human granulocytes to efficiently recognize and phagocytize A. fumigatus, which markedly impaired fungal killing. We conclude that corticosteroid treatment of granulocyte donors for increasing neutrophil yields or patients with ongoing corticosteroid treatment could result in deleterious effects on granulocyte antifungal functions, thereby limiting the benefit of granulocyte transfusion therapies against invasive fungal infections. / Der Mensch kommt über die Atemluft in regelmäßigem Kontakt mit Sporen des saprophyitschen Pilzes Aspergillus fumigatus. Glücklicherweise eliminieren die lokalen Abwehrmechanismen der Lunge den Pilz in gesunden Individuen sehr effektiv und ohne offenkundige Symptome. In immunkomprimierten Patienten hingegen verursacht A. fumigatus verheerende Infektionen. Allerdings ist die lokale Immunreaktion gegen A.fumigatus-vermittelte Infektionen der Lunge unter immunsuppressiven Bedingungen immer noch nicht ausreichend definiert. In Anbetracht der dynamischen Veränderungen an Immunzellunterpopulationen im Gewebe nach immunsuppressiver Therapie haben wir die zeitliche und örtliche pulmonale Immunreaktion nach A. fumigatus infektion untersucht, um die grundlegenden immunologischen Geschehnisse aufzudecken, die in dieser Situation zur unzureichenden Kontrolle des Pilzes führen. In anderen immunsupprimierten Mausmodellen fand eine starke Rekrutierung myeloider Zellen nach Infektion statt. In besonderem Maße wurden nach der Infektion Neutrophile und Makrophagen in die Lunge immunsupprimierter Mäuse rekrutiert. Andere myeloide Zellen, insbesondere dendritische Zellen und Monozyten, wurden nur im Corticosteroid-Modell nach Infektion rekrutiert. Lymphoide Zellen, insbesondere CD4+ oder CD8+ Zellen und NK Zellen, waren nach Immunsuppression stark reduziert und wurden nach Infektion mit A. fumigatus nicht rekrutiert. Adoptiver Zelltransfer von CD11b+ myeloiden Zellen stellte die Abwehr immunsupprimierter Mäuse gegen A. fumigatus wieder her, was die wesentliche Bedeutung dieser Zellen in der Immunabwehr unterstreicht. Diese Erkenntnisse verdeutlichen, dass CD11b+ myeloide Zellen unter immunkomprimierten Bedingungen entscheidend für die Abwehr gegen A-fumigatus sind. ...

Thesis (M. Phil.)--University of Hong Kong, 2009. / Includes bibliographical references (p. 90-103). Also available in print.

Background and Objectives: Type 1 diabetes (T1D) is an autoimmune disease that results from the immune-mediated destruction of insulin-producing β cells in the islets of Langerhans within the pancreas. A combination of genetic and environmental triggers has been acknowledged to contribute to the development of T1D. However, the detailed mechanisms underlying the initiation and progression of autoimmune diabetes still remain poorly understood. Recent studies have found that the reduction of circulating neutrophils is accompanied by neutrophil infiltration in the pancreas at the onset of T1D, suggesting that neutrophils may be causally involved in the pathogenesis of this disorder. However, further investigations are needed to clarify the precise roles of neutrophils and their cellular components in autoimmune destruction of pancreatic β cells. The objective of this study was to investigate whether neutrophil elastase (NE) and proteinase 3 (PR3), both neutrophil serine proteases stored in neutrophil primary granules, and NETosis, a unique form of cell death of neutrophils characterized by the release of decondensed chromatin and granular contents to the extracellular space, were involved in the pathogenesis of T1D. Key findings: 1) We developed several in-house immunoassays for the measurement of circulating levels of NE, PR3 and their endogenous inhibitor alpha-1 antitrypsin (A1AT), and validated the specificity, precision and sensitivity of these assays in clinical samples; 2) We provided the first clinical evidence demonstrating that both circulating protein levels and enzymatic activities of NE and PR3 were dramatically increased in patients with T1D, especially in those with disease duration less than one year. On the contrary, circulating concentrations of A1AT were significantly decreased in these patients; 3) By measuring circulating levels of myeloperoxidase (MPO)-DNA complexes, we demonstrated that NETosis was evidently increased in T1D patients, and positively correlated with the circulating protein levels as well as enzymatic activities of NE and PR3, suggesting that increased circulating NE and PR3 at least in part attributed to augmented NETosis; 4) Circulating NE and PR3 levels increased progressively with the increase in the positive numbers and titers of autoantibodies against pancreatic β cell antigens, but no significant correlation of NE or PR3 with fasting blood glucose levels was observed, suggesting that elevated NE and PR3 might be causally associated with β-cell autoimmunity, but not glycaemic status, in T1D patients. Furthermore, an obvious elevation of NE and PR3 was detected even in those autoantibody-negative patients, suggesting that circulating NE and PR3 may serve as a novel class of biomarkers for the early diagnosis of T1D. Conclusions: Our present study demonstrated that the drastic elevation of NE and PR3, accompanied by a decrease in the endogenous inhibitor A1AT and the enhancement of NETosis, are closely associated with the β-cell autoimmunity in patients with T1D. Measurement of circulating protein levels of neutrophil serine proteases and/or their enzymatic activities can be used to assist the differential diagnosis of autoimmune diabetes. / published_or_final_version / Medicine / Doctoral / Doctor of Philosophy

Thesis (Ph. D.)--University of Hawaii at Manoa, 1995. / Includes bibliographical references (leaves 149-171). / Microfiche. / xvi, 171 leaves, bound ill. 29 cm

Some mounted ill. / Bibliography: leaves 197-226 / xiv, 226, [137] leaves : ill. (some col.) ; 30 cm. / Title page, contents and abstract only. The complete thesis in print form is available from the University Library. / Thesis (Ph.D.)--University of Adelaide, Dept. of Clinical and Experimental Pharmacology, 1987

Diss. (sammanfattning) Göteborg : Göteborgs universitet, 2007. / Härtill 4 uppsatser.