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Inflammatory airway disease (IAD) is a common performance limiting pulmonary disorder in young racehorses in training. Although the precise aetiopathogenesis is poorly understood, proposed mechanisms include opportunistic bacterial infections and/or suboptimal air-hygiene. Since alveolar macrophages (AMs) are the first line defence in the lungs of mammalian species, they may constitute an appropriate therapeutic target cell in the treatment and the prevention of opportunistic airway infections. This thesis aimed to investigate the basic biology of the equine AM. A series of experiments were conducted to investigate the function and phenotype of this cell and comparisons made with equine macrophages derived from other anatomical sites and macrophage datasets derived from other species. The lung environment is unique, and may direct a unique phenotype and function compared with macrophages derived from other sites. Macrophages were isolated from the lungs, peritoneal cavity and other regions of healthy horses. Excellent cell recovery was demonstrated and associated with good viability, RNA yield and a demonstrable response to several stimuli, both when fresh and following cryopreservation. AMs produced tumor necrosis factor alpha (TNFα) when stimulated with lipopolysaccharide (LPS), polyinosinic-polycytidylic acid (Poly IC) and heat-killed Salmonella typhimurium and were actively phagocytic. By comparison, peritoneal macrophages (PMs) did not respond to these inducers and lacked phagocytic activity. In contrast to AMs, which showed high expression of the specific macrophage markers cluster of differentiation (CD) 14, CD163 and toll-like receptor 4 (TLR4), PMs lacked CD14. Moreover, gene expression analysis revealed an alternative macrophage activation for AMs, whereas PM showed a hybrid macrophage activation potentially attributed to the phenomenon of endotoxin tolerance. The response of equine AMs to LPS was analysed using microarrays. There was significant change in the expression of 240 genes. Those that were upregulated included well known inflammatory genes such as TNFα, IL1A and CXCL6. The pattern of response more closely resembled human and pig macrophages than mouse, including the LPS-induced expression of STAT4, IDO, IL7R genes and the failure to produce nitrite in response to LPS. These data suggest that the horse may represent a suitable animal model for human macrophage-associated lung inflammation, and conversely that data from humans may translate to horses. A final aim of this study was to investigate the effect of exercise on equine AM function. Therefore, AMs were isolated from bronchoalveolar lavage samples obtained from Standardbred racehorses at rest and during the training period and microarray analysis performed. Despite important limitations of the study, a few mechanisms at the molecular level were detected which may be involved in the development of either training-associated symptoms of, or susceptibility to IAD. Overall, this thesis aims to improve our understanding of equine macrophage biology and to provide useful information regarding the role of AMs in exercise-associated inflammation. Moreover, the findings presented here may help to inform future preventative pharmacological and/or managemental interventions for IAD.

by Chung Lap Chan. / "March 1999." / Thesis (Ph.D.)--Chinese University of Hong kong, 1999. / Includes bibliographical references (p. 270-307). / Electronic reproduction. Hong Kong : Chinese University of Hong Kong, [2012] System requirements: Adobe Acrobat Reader. Available via World Wide Web. / Mode of access: World Wide Web. / Abstracts in English and Chinese.

Os macrófagos (M<font face=\"Symbol\">&#934;s) compõem uma população celular altamente heterogênea, e são extensivamente adotados como ferramenta experimental, em especial os M<font face=\"Symbol\">&#934;s peritoneais murinos. O objetivo desse trabalho foi revisitar o peritônio dando ênfase à heterogeneidade dos M<font face=\"Symbol\">&#934;s. Duas populações distintas compõem os M<font face=\"Symbol\">&#934; peritoneais residentes: LPM (Large Peritoneal Macrophage) e SPM (Small Peritoneal Macrophage). Todas as condições proporcionadas in vivo resultam no desaparecimento de LPM, aumento de SPM e influxo de monócitos. Em paralelo, ocorre uma diminuição na marcação para <font face=\"Symbol\">b-galactosidase (marcador de senescência) e um aumento na produção de Óxido Nítrico (NO) e na frequência de células F4/80+IL-12+ após a subseqüente estimulação com LPS e IFN-<font face=\"Symbol\">g, que parece ser às custas da SPM. Além disso, parece haver uma especialização onde LPM assume um perfil M2 após inoculação de zimosan, e SPM um perfil M1 após reestimulo com LPS ou IFN-<font face=\"Symbol\">g.Esses dados sugerem que renovação celular que ocorre no peritônio após estimulação, parece ser benéfica para a resposta celular frente a estímulos infecciosos. / Macrophages (M<font face=\"Symbol\">&#934;) are a heterogeneous population extensively adopted as experimental model, especially peritoneal M<font face=\"Symbol\">&#934;. Then, the aim of this work was to revisit peritoneal cavity looking for M<font face=\"Symbol\">&#934; heterogeneity. Peritoneal M<font face=\"Symbol\">&#934; comprise two distinct subpopulations: LPM (Large Peritoneal Macrophage) and SPM (Small Peritoneal Macrophage). The different conditions proporcioned in vivo, resulted in the disappearance of LPM and the accumulation of SPM and monocytes. In parallel, adherent cells isolated from stimulated mice displayed reduced staining for <font face=\"Symbol\">b-galactosidase (senescence marker). Further, an increase in nitric oxide (NO) production and IL-12-producing cells frequency was observed in response to LPS/FN-<font face=\"Symbol\">g re-stimulation. In addition, there was a specialization of activation profile marked by a M2 activation profile after zymosan administered in vivo assumed by LPM, and SPM showed a bias to M1 after re-stimulation with LPS/IFN-<font face=\"Symbol\">g. Then, the substitution of LPM by a robust SPM and monocytes in response to infectious stimuli greatly improves peritoneal effector activity.

Os macrófagos (M<font face=\"Symbol\">&#934;s) compõem uma população celular altamente heterogênea, e são extensivamente adotados como ferramenta experimental, em especial os M<font face=\"Symbol\">&#934;s peritoneais murinos. O objetivo desse trabalho foi revisitar o peritônio dando ênfase à heterogeneidade dos M<font face=\"Symbol\">&#934;s. Duas populações distintas compõem os M<font face=\"Symbol\">&#934; peritoneais residentes: LPM (Large Peritoneal Macrophage) e SPM (Small Peritoneal Macrophage). Todas as condições proporcionadas in vivo resultam no desaparecimento de LPM, aumento de SPM e influxo de monócitos. Em paralelo, ocorre uma diminuição na marcação para <font face=\"Symbol\">b-galactosidase (marcador de senescência) e um aumento na produção de Óxido Nítrico (NO) e na frequência de células F4/80+IL-12+ após a subseqüente estimulação com LPS e IFN-<font face=\"Symbol\">g, que parece ser às custas da SPM. Além disso, parece haver uma especialização onde LPM assume um perfil M2 após inoculação de zimosan, e SPM um perfil M1 após reestimulo com LPS ou IFN-<font face=\"Symbol\">g.Esses dados sugerem que renovação celular que ocorre no peritônio após estimulação, parece ser benéfica para a resposta celular frente a estímulos infecciosos. / Macrophages (M<font face=\"Symbol\">&#934;) are a heterogeneous population extensively adopted as experimental model, especially peritoneal M<font face=\"Symbol\">&#934;. Then, the aim of this work was to revisit peritoneal cavity looking for M<font face=\"Symbol\">&#934; heterogeneity. Peritoneal M<font face=\"Symbol\">&#934; comprise two distinct subpopulations: LPM (Large Peritoneal Macrophage) and SPM (Small Peritoneal Macrophage). The different conditions proporcioned in vivo, resulted in the disappearance of LPM and the accumulation of SPM and monocytes. In parallel, adherent cells isolated from stimulated mice displayed reduced staining for <font face=\"Symbol\">b-galactosidase (senescence marker). Further, an increase in nitric oxide (NO) production and IL-12-producing cells frequency was observed in response to LPS/FN-<font face=\"Symbol\">g re-stimulation. In addition, there was a specialization of activation profile marked by a M2 activation profile after zymosan administered in vivo assumed by LPM, and SPM showed a bias to M1 after re-stimulation with LPS/IFN-<font face=\"Symbol\">g. Then, the substitution of LPM by a robust SPM and monocytes in response to infectious stimuli greatly improves peritoneal effector activity.

Die kontinuierliche Rezirkulation von Immunzellen durch periphere und sekundäre lymphatische Organe (SLOs) ist Bestandteil der Immunüberwachung und wichtig für die Aufrechterhaltung und Funktionsbereitschaft des Immunsystems. Der homöostatische Chemokinrezeptor CCR7 vermittelt dabei nicht nur die Rezirkulation von Lymphozyten durch SLOs, sondern scheint auch an der homöostatischen Rezirkulation von Lymphozyten durch nicht-lymphoide periphere Gewebe beteiligt zu sein. Im Rahmen dieser Arbeit wurde mithilfe von CCR7-defizienten Mäusen die funktionale Bedeutung von CCR7 für die homöostatische Rezirkulation von Lymphozyten durch das Peritoneum untersucht und nachgewiesen, dass CCR7 der dominante Chemokinrezeptor ist, der unter physiologischen Bedingungen die Transitzeit von Lymphozyten durch das Peritoneum festlegt. Die gestörte Rezirkulation von Lymphozyten begünstigte außerdem die Entstehung von tertiären lymphoiden Organen (TLOs) in der Magenschleimhaut von CCR7-defizienten Mäusen. Untersuchungen zur zellulären und molekularen Grundlage dieser und weiterer pathomorphologischer Veränderungen in der Magenschleimhaut von CCR7-defizienten Mäusen verdeutlichten die Funktion von CCR7 für die Etablierung von zentraler und peripherer Toleranz gegenüber gastrischen Antigenen. Fehlt CCR7, dann entwickelten Mäuse eine spontane Autoimmungastritis, welche durch gastritogene CD4+ T-Zellen verursacht wurde, deren Aktivierung auch unabhängig von Lymphknoten und TLOs erfolgte. Die Entstehung von TLOs wird auch bei einer durch Helicobacter pylori ausgelösten chronischen Gastritis beobachtet. Die Expression des homöostatischen Chemokinrezeptors CXCR5 und seines Liganden CXCL13 ist mit der Entwicklung dieser TLOs korreliert worden. Unter Verwendung eines Mausmodells für H. pylori-induzierte chronische Gastritis konnte gezeigt werden, dass CXCR5 die Ausbildung von TLOs vermittelt und eine Rolle für die Induktion von H. pylori-spezifischen T-Zell- sowie humoralen Immunantworten spielt. / Homeostatic recirculation of immune cells through peripheral and secondary lympoid organs (SLOs) is required for immune surveillance and the maintenance and functionality of the immune system. The homeostatic chemokine receptor CCR7 controls not only lymphoid cell trafficking to and within SLOs, but also seems to be involved in the homeostatic recirculation of lymphocytes through non-lymphoid peripheral tissues. Within the scope of this work we investigated the functional relevance of CCR7 for the homeostatic recirculation of lymphocytes through the peritoneal cavity and could show, that CCR7 is the dominant chemokine receptor which defines the transit time of lymphocytes in the peritoneal cavity under physiological conditions. Impaired recirculation of lymphocytes also promoted the development of tertiary lymphoid organs (TLOs) in the gastric mucosa of CCR7-deficient mice. Analysis of the cellular and molecular mechanisms underlying these and other pathomorphological alterations in the gastric mucosa of CCR7-deficient mice provided further evidence regarding the function of CCR7 for the establishment of central and peripheral tolerance towards gastric antigens. Mice that lack CCR7 spontaneously developed autoimmune gastritis, which was caused by gastritogenic CD4+ T-cells. Such autoreactive T cell responses were also initiated in the absence of lymph nodes and TLOs in CCR7/LT-alpha double-deficient mice. Development of TLOs is also observed during chronic gastritis induced by Helicobacter pylori. The expression of the homeostatic chemokine receptor CXCR5 and its ligand CXCL13 has been correlated with the development of these TLOs. Using a mouse model for H. pylori-induced chronic gastritis, we could show that CXCR5 is responsible for the development of TLOs and also plays a role for the induction of H. pylori-specific T and B cell responses.