Indivíduos diabéticos apresentam incidência elevada de doenças infecciosas. Isto pode estar relacionado às alterações na capacidade da resposta destes indivíduos aos agentes agressores. Em animais diabéticos, algumas destas alterações já foram descritas, assim como sua reversão pela administração de insulina. Este hormônio regula o metabolismo celular, modulando a atividade de proteínas e mediadores inflamatórios envolvidos neste processo. Sabemos que o lipopolissacarídeo (LPS) estimula, em macrófagos alveolares (MA) de animais não-diabéticos, a liberação do fator de necrose tumoral (TNF)-&#945; e do óxido nítrico (NO). O pré-tratamento deste MA com insulina inibiu todos estes efeitos. Assim, neste projeto, avaliamos o papel da insulina em MA e macrófagos peritoneais (MP) de camundongos, tornados diabéticos pela indução com aloxana (60 mg/kg, i.v.). Uma suspensão contendo 1x106 células foi estimulada com LPS (100 ng/mL) na presença ou não de insulina (1mU/mL). Realizamos a evolução temporal (0,5; 1; 3; 6; 24 horas) para a dosagem de NO, TNF-&#945; e interleucina (IL)-10. Nos tempos de maior produção destas citocinas (0,5 e 3 horas), também quantificamos IL-6, interferon (IFN)-&#947; e IL-4. Nossos resultados mostram que a produção/liberação dos mediadores imunes por MA e MP estimulados por LPS, quando tratados simultaneamente com insulina, tiveram uma redução. Assim, a produção/liberação de NO foi reduzida durante 0,5; 1; 3; 6, 24 horas, em MA e em MP; a liberação de TNF-&#945; foi reduzida durante 0,5 hora, em MP; a liberação de IL-6 foi reduzida durante 3 horas, em MA, e 0,5 hora, em MP. Estes dados mostram que a insulina reduziu a liberação destes mediadores inflamatórios, tanto para os MA quanto para os MP, durante o estímulo com LPS, de animais diabéticos já nos primeiros minutos de estímulo com LPS, com um pico de redução, na maioria das vezes, em 3 horas. / Diabetic patients exhibit high incidence of infectious diseases, at least in part, by due impaired immune response against aggressive agents. Lipopolysaccharide (LPS) triggers the releasing of tumor necrosis factor (TNF)-alpha and nitric oxide (NO) by alveolar macrophages (AM) of non-diabetic animals. The pretreatment using insulin inhibited of these cytokine release. The aim in the present study was to evaluate the insulin role on releasing of cytokines by MA and peritoneal macrophages (MP) of diabetic mouse. Resident AM and MP from diabetic (alloxan 60 mg/kg, i.v.) male C57BL/6 mice (CEUA/FCF/USP-339) stimulated by LPS (100 ng/mL). Insulin (1 mU/mL) insulin treatment was simultaneously with stimulus by LPS. Cytokines were measured by ELISA, and NO by Griess reaction. We performed a time course (0,5; 1; 3; 6; 24 hours), and measured NO, TNF-alpha and interleukin (IL)-10. We also measured IL-6, interferon (IFN)-&#947;, and IL-4 in 0.5 and 3 hours. Results were evaluated by analysis of variance (ANOVA) followed by multiple comparison Tukey-Kramer or the nonparametric Kruskal-Wallis test. P value were considered when <0.05. Before the induction of diabetes by alloxan injection in day 0 animals showed: weight (26±0,3 g) and blood glucose concentration (164±2,6 mg/dL) - and 10 days after the onset of the disease, diabetic mice presented a lower weight gain (24 ± 0,4 g*) and elevated blood glucose concentration (546±9,7 mg/dL*). An increase was seen NO release levels and TNF-alpha in the time course (Figure 1); an increase of IL-6 in 3 hours (Figure 3), and a decrease of IL-4 in 3 hours (Figure 5) after LPS stimulation of MA in diabetic animals. In MP, there was an increase of NO levels, and TNF-alpha in the time course (Figure 2); in 3 hours increased IL-6 levels (Figure 4) - under the same conditions. Insulin treatment under stimulation by LPS in MA reduced the levels of NO, IL-6, and TNF-alpha compared to the group stimulated by LPS. Regarding MP, insulin treatment also decreased NO levels, TNF-alpha, and IL-6. IL-4 levels produced by MP, and IFN-&#947; levels were not be detected in MA and MP under stimulation by LPS, or in the presence of hormone. These findings suggest that insulin reduce the release of these inflammatory mediators by both resident macrophages of diabetic animals concomitantly stimulation by LPS

It is clear that the voltage-gated proton channel HVCN1 plays an essential role in a range of cell types, in particular immune cells. Previous published work has confirmed the existence of proton channels in both murine and human macrophages. However, the role of HVCN1 in macrophages has not been investigated. Given that the current literature on voltage-gated proton channels in immune cells has found HVCN1 to be involved in several cellular processes (such as the respiratory burst and signalling events) it is important to establish its functional role in macrophages, which are a crucial constituent of the immune system. The aim of my thesis was to investigate the function of voltage-gated proton channels in macrophages with the use of mice with a disrupting mutation within the Hvcn1 gene, which results in HVCN1 loss. In particular, I wanted to address how Hvcn1-/- macrophages responded to LPS activation. I hypothesised that HVCN1 regulates the respiratory burst of macrophages and that it potentially modulates mitochondrial ROS production, and in doing so, may affect several functional aspects of macrophage biology.

Accumulating evidence highlights the importance of studying the migration of cells within the context of their natural environment as manipulating the substrate on which a cell is migrating can have a dramatic impact on the mode/mechanisms employed by cells during migration. Central to this phenomenon is the requirement of adhesion to the ECM in order to gain traction during migration. Integrins constitute the main family of cell receptors involved in mediating cell-ECM interactions during motility. Whilst traditionally two-dimensional cell culture studies have placed emphasis on the importance of these receptors for spreading and migration, it has become evident that within more confined environments these receptors, at least for some cell types, are less crucial. In this research we utilise Drosophila embryonic hemocytes as an in vivo model for cell migration. We show that whilst hemocytes migrate within confined environments in vivo, these cells depend on integrins for powering both developmental and inflammatory migrations. Given the close association between these receptors and the actin cytoskeleton we were surprised to discover that removal of the main β integrin subunit, Myospheroid, did not affect cell spreading in vivo and had only a small impact on lamellipodial structure and dynamics. Furthermore we discovered that, in contrast to other cell types previously analysed, removal of this integrin subunit in hemocytes was not accompanied by an increase in the rate of actin retrograde flow within the protrusions, which we believe could reflect abrogation of a positive feedback between Rho, ROCK and Myosin II contraction. Instead, we discover a key role for integrins in regulating the microtubule cytoskeleton, in the maintenance of a polarised microtubule bundle, termed a ‘microtubule-arm’. Although the molecular mechanisms by which this stabilisation is coordinated have yet to be identified, this provides important insight into the co-regulation of adhesion and microtubule cytoskeleton important for the migratory behaviour of these cells. Cell migration reflects the complex and integrated regulation of the actin cytoskeleton by diverse families of actin regulatory proteins. Using hemocytes as a model system, we also explore the regulatory interactions between two main actin regulatory proteins, Diaphanous and Enabled, in vivo. Whilst the function of these proteins in the formation of filopodial protrusions is overlapping, recent research has highlighted the ability of these proteins to regulate the activity of one another. We find that co-expression of Enabled in hemocytes is able to rescue the morphological and migratory defects resulting from overexpression of active Diaphanous. Thus, data here presents Enabled as a negative regulator of Diaphanous, which may play an important role in the migration of hemocytes in vivo.

"Tuberculosis is a deadly disease caused by bacteria of the genus Mycobacterium. One-third of the world’s population is infected with Mycobacterium tuberculosis. Two million these deaths occur each year in immunocompromised AIDS patients. M. tuberculosis has co-evolved with humans for many thousands of years. The bacillus has developed tactics to overcome the immune defense system and multiply in the macrophage. At the interface of the host and pathogen interactions, there is an interchange of metals and electrolytes. The host on one hand reduces the availability of metals essential for pathogen survival, like manganese and iron, in the macrophage and increases potassium ions which reduces pH in the phagolysosome. The host also generates Reactive Oxygen Species (ROS) and Reactive Nitrogen Species (RNS), to create toxic affects through interactions with metals and metalloproteins. M. tuberculosis copes with the hostile environment in the macrophage by preventing the acidification of the phagolysosome, secreting antioxidant enzymes such as alkylhydroperoxidase (AhpF) and peroxiredoxin (AhpC), superoxide dismutase, SodA and SodC, and catalase KatG through the SecA system. M. tuberculosis contains 28 metal transporters, among them there are 12 unique P-type ATPases. This is an unusually high number of P-type ATPases in an organism. These ATPases transport several monovalent and divalent metals (Cu+, Cu2+, Ag+, Zn2+, Na+, K+, Ca2+, Cd2+, Pb2+, Mn2+, Mg2+, and Co2+) across biological membranes, using energy from ATP hydrolysis. Our analysis has revealed that these P-type ATPases have homologs in other intracellular symbiotic/pathogenic bacteria and certain chemolithotrophic archaea and bacteria. A corelation can hence be drawn among these pumps and the capability of surviving in noxious environments and coping with adverse redox conditions. Possible substrates were identified by determining the consensus sequences in different helices of these ATPases. However, out of the 12 P-type ATPases confirmed, transported substrate could be postulated for four of these proteins; CtpA, CtpB, CtpV and KdpB. Using bioinformatic approaches we have characterized the possible genetic environment of these genes. The transmembrane regions were analyzed for consensus sequences and the N-terminals and C-terminals were scrutinized for metal binding domains, and we were able to categorize these ATPases into P1 type and P2 type ATPases. In an attempt to determine the substrate specificity, two of these ATPases (CtpC and ctpG) were cloned and transformed into Escherichia coli cells. Cells expressing CtpC were grown in different concentrations of metals and pHs. In these experiments CtpC was found to show an interaction with copper and cadmium. Pure protein was obtained by His-tag purification and para-Nitro Phenol Phosphatase (pNPPase) assay was performed with different metals, it was found that copper and zinc activated the phosphatase activity of the enzyme; and cobalt and manganese were inhibitory. Inhibition of the pNPP assay could mean that there would be activation in the ATPase assay, meaning that cobalt and manganese could be possible substrates to this enzyme. "

Aging is associated with a loss of cognitive function related to learning, memory, and executive function with varying severity. Although there is no age-related loss of neurons in healthy aging, myelin damage accumulates and is associated with cognitive decline. The brain’s resident macrophages, microglia, are responsible for clearing damaged myelin and promoting subsequent oligodendrocyte-mediated remyelination. To test the hypothesis that age-related dysfunction of microglial phagocytosis and oligodendrocyte remyelination capacity contributes to myelin pathology and cognitive impairment. To test this, rhesus monkeys from across the lifespan (7-30 years of age) were tested in three specific aims. 1) To characterize gene expression of myelin basic protein (MBP) in the brain and clearance of MBP to the cerebrospinal fluid (CSF) in relation to age-related myelin pathology. The density of myelinated axons visualized using label-free spectral confocal reflectance imaging did not correlate with age, but was significantly lower in aged animals with cognitive impairment. Next, MBP gene expression was measured using qPCR in the dorsal prefrontal cortex along with quantification of MBP protein levels in the CSF using ELISA. Age-dependent increases of MBP gene expression in the brain and MBP protein levels in the CSF were observed. Interestingly, MBP levels in the CSF were lower in animals with cognitive impairment. 2) To test the hypothesis that microglia would become increasingly primed for phagocytosis with age-related myelin pathology. The number of microglia immunostained with galectin-3, a marker for phagocytic activation, was quantified in the frontal white matter and increases in both aging and cognitive decline were detected. 3) To evaluate the hypothesis that lipofuscin, an age-related accumulation indicative of autophagic dysfunction, would accumulate and impair glial cells of the white matter in aged animals. Lipofuscin accumulation was increased with age in the frontal white matter and the size of lipofuscin clusters was associated with cognitive impairment. Lipofuscin was found primarily in microglia and oligodendrocytes, but not in astrocytes. These data suggest that lipofuscin burden in microglia and oligodendrocytes inhibits their homeostatic functions resulting in improper myelin clearance and turnover, leading to a devastating feed-forward cycle of myelin damage that contributes to age-related cognitive impairment.

A disfunção do sistema imune inato e a neuroinflamação tem sido cada vez mais reconhecidas como elementos importantes na fisiopatologia do transtorno bipolar (TB). Como componentes essenciais da imunidade inata, os macrófagos tem múltiplas funções tanto na inibição como na promoção da proliferação celular e na reparação tecidual, sendo a diversidade e a plasticidade características marcantes deste tipo celular. A polarização M1 clássica e a polarização alternativa M2 de macrófagos representam dois extremos de um estado dinâmico na mudança da ativação dos mesmos. Os macrófagos do tipo M1 sintetizam citocinas próinflamatórias que inibem a proliferação de células circundantes e danificam tecidos, enquanto os macrófagos do fenótipo M2 liberam citocinas antiinflamatórias que podem promover reparo tecidual. Um desequilíbrio da polarização M1-M2 dos macrófagos é frequentemente associado a várias doenças ou condições inflamatórias. O objetivo desta tese foi, além de revisar a importância da inflamação sistêmica na modulação da resposta inflamatória da microglia/macrófagos e consequentemente seu potencial envolvimento na fisiopatologia do TB, avaliar o perfil de polarização M1/M2 em cultura de macrófagos de sujeitos com TB comparados a indivíduos saudáveis. Monócitos foram isolados a partir de sangue periférico de dez sujeitos com TB e dez indivíduos saudáveis e diferenciados em macrófagos através da adição de fator estimulante de colônia de macrófagos (MCSF) ao meio de cultura. Para induzir a polarização M1 ou M2, as culturas foram incubadas com IFN-y e LPS ou IL-4 respectivamente. Após a incubação, recolheram-se os sobrenadantes e mediram-se as citocinas (IL-1β, IL-6, IL-10 e TNF-α) por ensaio multiplex. A secreção das citocinas IL-1β, TNF-α e IL-6 características do protótipo M1 e citocinas IL-10 do protótipo M2 foram semelhantes entre os pacientes e os controles. Utilizou-se a razão TNF-α / IL-10 do fenótipo M1 para refletir o estado inflamatório dos participantes. Não foi observada diferença entre os grupos (p=0,627). Duas hipóteses diferentes poderiam explicar esses resultados: todos os pacientes incluídos neste estudo representam um estágio inicial da doença como evidenciado pela pontuação FAST total inferior a 11. De acordo com o modelo de estadiamento em TB, as alterações biológicas (incluindo a inflamação) parecem estar relacionadas com os episódios de humor e progressão da doença. Juntamente com estudos anteriores, os nossos dados sugerem que os pacientes nos estágios iniciais ainda preservam a função do sistema imunológico sem apresentar um desequilíbrio a favor do perfil de macrófagos M1 como tem sido observado em pacientes no estágio tardio, destacando a relevância da intervenção precoce no TB. Ainda, estes pacientes estavam em tratamento com estabilizadores de humor e é plausível especular que esses fármacos exerçam efeitos sobre a polarização de macrófagos. Estudos futuros em pacientes drug-free são essenciais para avaliar esta questão. Em conclusão, nossos achados sugerem que os pacientes TB não apresentam desequilíbrio na polarização dos macrófagos em favor do fenótipo pró-inflamatório M1. O fato de todos estes pacientes estarem em estágios iniciais da doença reforça os efeitos protetores da intervenção precoce no TB na prevenção de alterações do sistema imune e, consequentemente, na progressão da doença. / Innate immune system dysfunction and neuroinflammation have been recognized as important elements in the pathophysiology of bipolar disorder (BD). As essential players of innate immunity, macrophages have multiple roles in inhibition and promotion of cell proliferation and tissue repair. The classical M1 polarization and the M2 alternative polarization of macrophages represent two extremes of a dynamic state in their change of activation. M1 macrophages synthesize proinflammatory cytokines that inhibit the proliferation of surrounding cells and damage tissues, whereas macrophages of the M2 phenotype release antiinflammatory cytokines that may promote tissue repair. An imbalance of the M1-M2 polarization of macrophages is often associated with various diseases or inflammatory conditions. The aim of this thesis was to review the importance of systemic inflammation in modulating the inflammatory response of microglia/ macrophages and consequently their potential involvement in the pathophysiology of BD, and also evaluate the M1/M2 polarization profile in macrophages of patients with BD compared to healthy individuals. Blood monocytes were obtained from ten BD patients and ten healthy controls. These cells were activated/polarized into the M1 (IFNγ + LPS) or M2(IL-4) phenotype. Supernatants were collected and the cytokines (IL-1β, IL-6, IL-10 and TNF-α) were measured by multiplex assay. Secretion of the IL- 1β, TNF-α, IL-6 and IL-10 were similar between patients and controls. The TNF-α/IL- 10 ratio of the M1 phenotype was used to reflect the inflammatory state of the participants. There was no difference between groups (p = 0.627). Two hypotheses could explain these results: all patients included in this study represent an early stage of disease as evidenced by the FAST score below 11. According to the BD staging model, biological changes (including inflammation) appear to be related to mood episodes and disease progression. Together with previous studies, our data suggest that patients in early stages of BD still preserve immune system function without presenting an imbalance in favor of M1 macrophages as has been observed in latestage patients, highlighting the relevance of early intervention. Moreover, these patients were under treatment with mood stabilizers and it is plausible to speculate that these drugs have effects on macrophage polarization. Future studies in drug-free patients are essential to assess this issue. In conclusion, our findings suggest that BD patients do not present imbalance in macrophage polarization in favor of the M1 proinflammatory phenotype. The fact that all these patients are in the early stages of the disease reinforces the protective effects of early intervention in BD to prevent changes in the immune system and, consequently, prevent the progression of the disease.

A Mycobacterium abscessus subspécie abscessus é um pesadelo quando envolvida em infecção pulmonar que são incuráveis, a despeito do uso de antimicrobianos com atividade in vitro, caso o tratamento não inclua a ressecção cirúrgica da área afetada. É a micobactéria patogência de crescimento rápido mais frequentemente isolada de culturas de sítios pulmonares. Há um número reduzido de opções terapêuticas para o tratamento dessas infecções, e é ainda mais reduzido o número de antimicrobianos que atingem concentrações terapêuticas no compartimento intracelular, em particular no fagossomo. O número limitado de antimicrobianos disponíveis para tratamento apontam a necessidade de determinação do perfil de susceptibilidade frente a antimicrobianos isolados e em combinação, nos compartimentos intra e extracelular. Os objetivos deste estudo foram avaliar: a sensibilidade de M. abscessus estruturadas em biofilmes e presentes no interior dos macrófagos; a ocorrência de sinergismo quando da associação entre fármacos, inibidores de betalactamase e o anti-inflamatório. As combinações entre os antimicrobianos foram apenas indiferente quanto ao FIC e a atividade dos fármacos em biofilme e em macrófagos é bacteriostático. / Mycobacterium abscessus subspecies abscessus is a nightmare when involved in lung infection that is incurable, despite the use of antibiotics with in vitro activity, if the treatment does not include surgical resection of the affected area. It is a MCR - rapidly growing mycobacteria pathogenic most frequently isolated from cultures of lung sites. There are a small number of therapeutic options for the treatment of such infections is further reduced and the number of drugs that reach therapeutic concentrations in the intracellular compartment, particularly in the phagosome. The limited number of antimicrobials available for treatment indicate the need for determining the susceptibility profile against antimicrobials alone and in combination, in the intra and extracellular compartments. The objectives of this study were sensitivity of MCR structured biofilms and present in macrophages, the occurrence of synergism when the association between drugs, beta-lactamase inhibitors and anti-inflammatory. Combinations of antimicrobials were just indifferent and the activity of drugs on biofilms and macrophages was bacteriostatic.

Efferocytosis, the clearance of apoptotic cells including apoptotic neutrophils by macrophage phagocytosis, is a key cellular mechanism for resolution of inflammation and tissue repair. Cyclin-dependent kinases (CDKs) 7 and 9 phosphorylate RNA polymerase II that is vital for neutrophil transcriptional capacity. CDK inhibitors such as R-roscovitine, and the more selective inhibitor AT7519, induce neutrophil apoptosis and promote resolution of several mouse models of inflammation including acute lung inflammation. The hypothesis investigated here was that AT7519 would promote neutrophil apoptosis (i) in the infarcted heart, leading to macrophage polarisation, angiogenesis, reduced infarct expansion and retention of cardiac function and (ii) in the peritoneum, enhancing resolution of sterile peritonitis. AT7519 (1μM) induced apoptosis of mouse unstimulated-bone marrow derived neutrophils and thioglycollate-stimulated neutrophils in vitro in a time- and caspase-dependent manner, but did not alter activation assessed by calcium flux in response to the synthetic formyl peptide (fMLF) or platelet-activating factor (PAF). Only high concentrations of AT7519 (10 μM) induced monocyte/macrophage apoptosis and this was likely due to saturated phagocytosis of apoptotic neutrophils induced by high concentration of AT7519. Myocardial infarction (MI) was induced by coronary artery ligation in adult male mice and infarct volume was assessed 7 or 21 days later by in vitro optical projection tomography (OPT). The novel use of OPT for this purpose was validated by demonstrating correlation with infarct volume obtained by late-gadolinium enhanced magnetic resonance imaging in vivo and with infarct area assessed by histological staining (Masson’s Trichrome) in tissue sections. AT7519 (30 mg/kg i.p.) increased the number of apoptotic neutrophils (cleaved caspase-3 and Ly6G +ve) in the heart when administered after MI, but this was not associated with any subsequent alteration in macrophage polarisation, vessel density, infarct expansion or structural and functional remodelling of the left ventricle. In contrast, induction of neutrophil apoptosis by AT7519 (30mg/kg i.p.) successfully promoted macrophage polarisation and the resolution of inflammation associated with peritonitis elicited by either 10% thioglycollate or by 1mg zymosan. AT7519 treatment also reduced the number of CD19+ B cells, Foxp3+CD4+ T cells and eosinophils in peritoneal lavage, and prolonged the phase of monocyte recruitment in zymosan-induced peritonitis. In conclusion, AT7519 successfully induced mouse neutrophil apoptosis in vitro, as well as in vivo in experimental MI and peritonitis. Subsequent promotion of inflammation resolution in peritonitis was not matched by improved outcome following MI. Unexpected effects of CDK inhibition on monocytes, T cells and eosinophils that are necessary for myocardial infarct repair may have compromised any beneficial effects resulting from promotion of in situ neutrophil apoptosis. CDK inhibition may therefore have therapeutic potential for the treatment of peritonitis, but not for prevention of infarct expansion and detrimental ventricular remodelling after MI.

Neutrophils are an important cell in host defence and migrate rapidly to sites of inflammation when the host is compromised (e.g., in infection or wounding). There, they produce and/or release inflammatory mediators (e.g., LTB4, TNF, IL-8) and ingest and degrade pathogens (e.g., by release of granule proteins and reactive oxygen species). Neutrophils then undergo apoptosis and are cleared by phagocytes such as macrophages, to allow efficient resolution of inflammation. Inducing neutrophil apoptosis by pharmacological means could be a therapeutic strategy to dampen inflammation in diseases where neutrophils are prevalent, e.g., acute respiratory distress syndrome (ARDS) and rheumatoid arthritis (RA). Inhibition of cyclin-dependent kinases (CDKs) using CDK inhibitor (CDKi) compounds induces mammalian neutrophil apoptosis in vitro, and can drive resolution of inflammation in vivo in mouse models. Evidence indicated that this is due to inhibition of CDK9 and CDK7-mediated transcription of the anti-apoptotic protein Mcl-1. The hypothesis of this project was that CDK9, CDK7 and Mcl-1 are pivotal regulators of resolution of inflammation in vivo. The model selected to test this hypothesis was tailfin injury of embryonic zebrafish (Danio rerio). Zebrafish are optically transparent and reporter transgenic lines with neutrophils labelled by enhanced GFP (EGFP - Tg[mpx:EGFP]i114) and macrophages (Tg[MPEG1:mCherry]) have been created, permitting the imaging of the behaviour of these cells in vivo. The model of tailfin transection was chosen to cause an inflammatory response in these animals, with neutrophil and macrophage recruitment to the tailfin. This response was manipulated using CDKi compounds and specific gene knockdowns (using morpholino and CRISPR/cas9 technologies). It was shown that CDKi compounds could reduce neutrophil numbers at 24 h post-injury at the transected tailfin, but did not affect macrophage numbers. The CDKi AT7519 increased neutrophil apoptosis at 12 h post-injury. Specific CDK9 knockdown using morpholinos or CRISPR/cas9 also reduced neutrophilic inflammation at the tailfin 24 h after transection, accompanied by increased apoptosis levels at 8 h in the morpholino-treated group. Inhibition of an endogenous CDK9 inhibitor, LaRP7, had the opposite effect and increased neutrophil numbers; and could oppose the neutrophil- reducing effect of AT7519 and CDK9 morpholino knockdown. Preliminary genetic knockdown studies into the roles of CDK7 and Mcl-1 have been carried out. Taken together, the results demonstrate CDK9 is important in the resolution of neutrophilic inflammation, indicating that manipulation of CDK9 activity could be a good target for therapeutic intervention in inflammatory disease.

Colony-Stimulating Factor (CSF-1) is required for the proliferation, differentiation and survival of cells of the mononuclear phagocyte lineage. Mice with a mutation in their CSF-1 gene demonstrate abnormal development in many organ systems and severe growth retardation. These defects can be corrected by administration of rh- CSF-1, and when similarly administered to wild-type mice, can increase organ and body weight, thus highlighting the importance of CSF-1 in postnatal growth. CSF-1 is known to be elevated in the circulation in the immediate postnatal period of both mice and humans. It remains to be seen whether CSF-1 deficiency underlies important clinical issues such as low birth weight, and whether there are any functionally important variations in expression or biology of CSF-1, or the alternative CSF-1R ligand IL-34 that contributes to variation in somatic growth between individuals. This thesis aimed to use the pig as a model for human innate immunity and disease based upon recent publications that highlighted the similarities in their immune systems. To investigate the effects of CSF-1 on postnatal growth the first aim was to characterise the CSF-1R system in pigs and produce reagents. Biologically active porcine CSF-1 and IL-34 were produced along with expression of full length functional porcine CSF-1R and production of anti-CSF-1R antibodies. A bioassay was developed and optimised to assess the biological activity of these proteins. The cross-species reactivity of a range of species CSF-1 and IL-34 proteins was investigated in-vitro using the bioassay and cell culture systems. Recombinant CSF-1 is known to have a short half-life. Since conjugation of proteins to the Fc region of immunoglobulins has been used extensively to improve circulating half-life; a porcine Fc CSF-1 fusion protein was generated by commercial partners, Pfizer Animal Health. The conjugated and un-conjugated CSF-1 proteins had identical activity in cell line and primary cell assays in-vitro. The in-vivo activity of porcine Fc CSF-1 was tested initially in the Csf1r-EGFP+ mouse reporter line and C57BL/6 mice. The Fc CSF-1 protein was more active than the native protein in promoting increased monocyte and tissue macrophage numbers, increasing body weight and inducing hepatosplenomegaly. Hepatic growth was associated with extensive macrophage infiltration and hepatocyte proliferation, identified by gene expression profiling as well as immunohistochemistry. Fc CSF-1 was then tested in neonatal pigs. They were found to have an immature immune system that develops with age. No postnatal surge of CSF-1 was detected. Fc CSF-1 administration increased blood monocyte and neutrophil numbers confirming that CSF-1 is not saturating at this time. Nevertheless, no influence on postnatal growth rate was identified. This is discussed in terms of the differences in placental architecture in the pig compared to human and mouse. This thesis demonstrates the effectiveness of porcine Fc CSF-1 in both mice and porcine and highlights the important role that CSF-1 and macrophages play in liver homeostasis. Fc CSF-1 is identified as candidate therapeutic agent in humans and companion animals for tissue regeneration, and a tool for the study of the role of macrophages in physiology and pathology.