Sepsis is an exaggerated inflammatory syndrome involving cell, organ and system dysregulation. This dysregulation is detrimental to the patient, mainly as it causes imbalances in the immune system. Monocytes and neutrophils are key cell players in the pathogenesis of sepsis; Two populations that follow divergent apoptotic fates; most importantly delayed neutrophil apoptosis has been demonstrated in sepsis and may contribute to organ damage. These two subpopulations have recently been referred to as specific targets of leukocyte filtration, a noveltherapeutic approach in septic patients. As the molecular mechanisms driving the survival/death switches of these cells in sepsis is still controversial, we decided to investigate the role of a new family of proteins predicted to be involved in inflammation and cell death mechanisms; the ApoLs. We studied ApoL expression in whole blood leukocytes and purified populations of neutrophils and monocytes from healthy volunteers and patients with or without sepsis. We then correlated ApoL expression to the degree of inflammation (CRP levels) and cellular apoptosis. We showed a down regulation in ApoL expression in septic and non-septic patients as compared to healthy volunteers, whereas purified monocytes showed an up regulation of ApoL1 and ApoL2 expression in septic patients as compared to non-septic patients. Given that these cells behave differently in the septic frame, we aim to investigate and invalidate the role of ApoLs in conditions related to cell activation and death. Given the high degree of variability in human samples, we resorted to an in-vitro cell line, the PLB 985 myelomonoblastic cell line with granulocytic differentiation potential. Culturing these cells in RPMI 1640 in the presence of specific differentiation agents resulted in mature terminally differentiated cells with phenotypic and functional similarities to human neutrophils. This was determined by monitoring specific leukemic and granulocytic markers. This cell model will help us to better understand the role ofApoLs in regulating neutrophil half-life particularly in inflammatory conditions. It can also be employed to characterize “The cytokine(s)” that is inducing a change in ApoL expression and ultimately uncover the signaling pathway dictating both ApoL expression and apoptosis/survival. / Le sepsis est defini comme une reponse inflammatoire exageree, associee a une dysfonction d'organes faisant suite a un desequilibre du systeme immunitaire. En effet, les monocytes et les neutrophiles representent les acteurs cle dans la physiopathogenese du sepsis. Etant donne que les mecanismes moleculaires regulant la balance de survie / mort cellulaire de ces deux populations de cellules restent jusqu'a present controverses, nous nous sommes interesses a etudier l'implication d'une nouvelle famille de proteines: les apols, susceptibles d'intervenir dans le processus inflammatoire et de la mort cellulaire. Nous avons explore l'expression des apols dans les leucocytes totaux et dans les populations de neutrophiles et de monocytes purifiees a partir de donneurs sains et de patients septiques et non septiques. Par la suite, nous avons etablit le lien de correlation entre l'expression des apols, le degre d'inflammation systemique (dosage de la crp) et l'apoptose. Nos resultats ont demontre une baisse de l'expression des apols dans les leucocytes totaux el les neutrophiles purifies, chez les patients septiques et non septiques, en comparaison avec les donneurs sains. En revanche, nous remarquons une surexpression de l'apol1 et l'apol2 chez les patients septiques par rapport aux patients non septiques. Etant donne la grande variabilite dans les echantillons preleves, nous avons procede a la differenciation d'une lignee myelomonoblastique ayant un pouvoir de differenciation granulocytaire. La mise en culture de cette lignee dans les conditions de differenciation adequates, nous a permis d'obtenir des cellules ayant des similarites fonctionnelles et phenotypiques aux neutrophiles humains. Ce modele cellulaire va nous aider d'une part, a mieux comprendre l'implication des apols dans le controle de la viabilite cellulaire dans les conditions inflammatoires; et d'autre part, a caracteriser la / (les) cytokine(s) susceptibles de moduler l'expression des apols; et finalement a decortiquer la voie de signalisation impliquant les apols dans le controle du processus de survie ou de mort cellulaire. / Doctorat en Sciences / info:eu-repo/semantics/nonPublished

Le cytosquelette se compose de microfilaments (polymères d’actine), de microtubules (polymères de tubuline) et de filaments intermédiaires (polymères de desmine, de lamines …). Le sepsis défini par une infection associée à une réaction inflammatoire systémique est responsable de dysfonctions myocardiques de mauvais pronostique. Cette cardiomyopathie apparait dans les premières heures du sepsis et guérit en moins de deux semaines chez les survivants. Même si certaines études démontrent l’implication d’éléments du cytosquelette dans la cardiomyopathie septique, les rôles des microfilaments et des microtubules ne sont pas clairement établis.Macrophage migration inhibitory factor (MIF) est une cytokine pro-inflammatoire sécrétée en excès dans le sepsis qui serait responsable d’un ralentissement de la récupération myocardique. Dans un premier temps, notre travail a consisté à caractériser l’implication des microtubules dans la dysfonction musculaire cardiaque induite par MIF. Dans un modèle de trabécules auriculaires droites humaines nous avons démontré que MIF induit une hyperpolymérisation des microtubules responsable d’une hyperviscosité intracellulaire, d’une dysfonction mitochondriale et d’une dysfonction contractile. Nos résultats suggèrent qu’une hyperpolymérisation des microtubules induite par MIF pourrait être responsable d’un ralentissement de la récupération myocardique à la phase tardive de la myocardiopathie septique. Dans un second temps, nous avons évalué l’implication des microfilaments dans un modèle murin de dysfonction myocardique inflammatoire induite par l’injection d’une endotoxine bactérienne, le lipopolysaccharide. Nos résultats suggèrent qu’à la phase précoce de la cardiomyopathie inflammatoire il existe une hyperpolymérisation des microfilaments responsable de dysfonctions contractile et mitochondriale.Les connaissances fondamentales acquises au cours de ce travail de thèse suggèrent une implication directe des microtubules et des microfilaments dans la physiopathologie des cardiomyopathies inflammatoires. / The cytoskeleton is composed of intracellular microfilaments (actin polymers), microtubules (tubulin polymers) and intermediate filaments (desmin, lamin … polymers).Sepsis, the association of an infection and a systemic inflammatory response, induces myocardial dysfunction. Septic cardiomyopathy appears in the early phase of sepsis and is associated with fatal outcome. Complete recovery of myocardial function occurs within two weeks following the onset of myocardial dysfunction in surviving patients. Although several studies demonstrate a role of cytoskeleton in septic cardiomyopathy, the involvement of microfilaments and microtubules is not clear.Macrophage migration inhibitory factor (MIF) is a pro-inflammatory cytokine secreted during sepsis that is suggested to postpone myocardium recovery. The first aim of the study was to characterize microtubule implications in MIF-induced cardiac muscle dysfunction. In a model of human right atrial trabecule we demonstrated that MIF induces microtubule stabilizations which are responsible for high intracellular viscosity, contractile and mitochondria dysfunctions. Our results suggest that MIF-induced microtubule stabilizations might be responsible for a delay of myocardial recovery during septic cardiomyopathy. The second aim of the study was to characterize microfilament involvements in a murine inflammatory cardiomyopathy induced by a lipopolysaccharid (LPS) injection. Our results suggest that microfilament stabilizations might be responsible for LPS-induced contractile and mitochondria dysfunctions in the early phase of inflammatory cardiomyopathy. Thus, these new fundamental mechanisms suggest a direct involvement of microtubules and microfilaments in the development and evolution of inflammatory cardiomyopathies.

Sepsis är en diagnos med hög mortalitet, men svår för ambulanssjukvården att upptäcka. Ett snabbt förlopp till behandling är av största vikt och en utmaning för ambulanssjuksköterskans förmåga att korrekt bedöma patienter med misstänkt sepsis. Syftet med studien var att undersöka utlarmningsprioritetens betydelse för tid till olika behandlingsinterventioner för patienter med ett svårt infektionstillstånd samt hur ambulanssjuksköterskans bedömning och behandling av dessa påverkade vårdförloppet avseende tid till antibiotikabehandling, vårdtid och mortalitet. Forskningsansats var retrospektiv journalgranskning. Resultatet visar att ambulanssjuksköterskan uppgraderat larmcentralens prioritering till högsta prioritet i 33,4 % av fallen. Patienterna fick vänta längre på ambulans vid lägre utlarmningsprioritet. Ambulanssjuksköterskan identifierade en svårt sjuk patient lika fort oberoende av utlarmningsprioritet. En misstanke om sepsis fanns redan i ambulansen i 64,4 % av patientfallen. Denna misstanke var associerad till förkortad tid till antibiotikabehandling på akutmottagningen. Denna patientgrupp fick också administrering av prehospital läkemedelsbehandling i större utsträckning. Mortaliteten vid sepsis har i tidigare studier halverats vid en sådan misstanke, men det kunde inte påvisas i denna studie. Möjligen beror det på ett lite annorlunda arbetssätt inom svensk ambulanssjukvård samt annorlunda inklusionskriterier för studien. Det finns idag en mängd olika screeninginstrument för sepsis. Valideringen av dessa pågår och frågan hur ambulanssjuksköterskan på bästa sätt skall tidigt upptäcka sepsis kvarstår. Behandlingsriktlinjerna vid sepsis är inte i linje med senaste forskning och tydliga behandlingsanvisningar saknas för ambulanssjukvården. Det är behov av ytterligare forskning rörande ambulanssjuksköterskans bedömningar och hur beslutsvägar görs.

Objective: Unknown ethiology Background: Capnocytophaga ochracea is a gram-negative anaerobic organism commonly found in human oral flora. It is characteristically sensitive to beta-lactams and resistant to aminoglycosides. Case Report: A 23-year-old woman presented with lower abdominal pain and was admitted for premature labor at 24-weeks of gestation. At presentation, the cervix was closed and the membrane was intact; however, contractions continued, the membrane subsequently ruptured before receiving any steroids or magnesium, and the mother gave birth to a 540-gram female baby. At birth, Apgar scores were 1 at 5 minutes, 1 at 10 minutes, and 2 at 15 minutes. On the fifth day of life, the blood culture grew Capnocytophaga species. Consequently, Cefotaxime was started and ampicillin continued for a total of 14 days; however, on the 6th day, the head ultrasound showed grade 4 intraventricular hemorrhage and a Do Not Resuscitate (DNR) order was placed in the chart. The patient's health continued to deteriorate, having multiple episodes of bradycardia and desaturation until cardiac arrest on the 17th day. Conclusions: Capnocytophaga ochracea was isolated from the blood culture of a preterm neonate. It was thought to be the cause of the premature labor and subsequent neonatal septicemia. This case report suggests that the prevalence of Capnocytophaga infections is most likely underestimated and that additional premature labors and abortions could have been caused by Capnocytophaga infections that were never detected. Hence, more studies are needed to investigate the route of transmission.

Neutrophil extracellular traps (NETs), chromatin released by activated neutrophils, were first described for their antimicrobial properties. NETs have a backbone of DNA and histones lined with microbicidal proteins such as neutrophil elastase. NET release has pathological consequences, particularly within blood vessels where NETs can trap red blood cells and platelets, thus contributing to thrombosis (Chapter 1-Overview). NET formation (NETosis) is an active and coordinated biological process involving many enzymatic components. One enzyme in particular, peptidylarginine deiminase 4 (PAD4), citrullinates histones and is required for chromatin decondensation during NETosis. Neutrophils from PAD4-deficient mice are unable to form NETs. We obtained these mice from our collaborator Dr. Yanming Wang, and thus were able to compare PAD4-/- mice to wild-type (WT) mice in mouse models where NETs are formed. These studies have allowed for investigation of the biological relevance of PAD4 and NETs in vivo in thrombotic and/or inflammatory disease. This dissertation focuses on mouse models of deep vein thrombosis and of sepsis. In venous stenosis, thrombosis is initiated by restricting blood flow in the inferior vena cava (IVC). Here, PAD4-/- mice were greatly protected from thrombus formation (Chapter 2). Leukocyte rolling and platelet plug formation in response to vessel injury were unaffected, indicating that endothelial and platelet activation occurred normally in these mice. The mice did not exhibit any defects in hemostasis, and could be induced to produce deep vein thrombi by infusion of WT neutrophils that formed NETs as a part of the thrombus scaffold. Because there is potential to develop anti-NET therapies in thrombosis, I investigated if NET-deficiency would render mice immunocompromised (Chapter 3). PAD4-/- mice had similar mortality in the cecal ligation puncture model, and they were protected from shock in an LPS sepsis model where NETs are released in the absence of live bacteria. Therapies aimed at NET prevention or destruction would likely be beneficial without compromising host immunity. Thus, in summary, studying PAD4-deficient mice has revealed the impact of NETs in thrombotic/inflammatory disease and identified PAD4 as an attractive therapeutic target.

Le sepsis est la réaction inflammatoire généralisée secondaire à une infection. C’est une pathologie fréquente et grave qui fait intervenir le système immunitaire. L’action de l’immunité innée se fait par l’activation et le recrutement des monocytes, des cellules mononuclées circulantes qui modulent le phénomène inflammatoire. La mobilisation des monocytes fait intervenir les cytokines chimiotactiques (chimiokines) et leurs récepteurs. Nous nous sommes spécifiquement intéressé dans ce travail au rôle de l’expression monocytaire des récepteurs aux chimiokines CCR2 et CX3CR1 au cours du sepsis. Pour ce faire, nous avons utilisé des modèles murins de sepsis et analysé le rôle d’un polymorphisme génétique de CX3CR1 dans une cohorte de malades atteints de sepsis. Nous avons montré qu’au cours du sepsis, les monocytes présentaient une augmentation de l’adhérence aux parois vasculaire contrôlée par le récepteur CX3CR1. Nous avons également montré que les monocytes inflammatoires jouaient un rôle essentiel dans la régulation du phénomène inflammatoire au cours du sepsis en protégeant le rein des lésions septiques. Cette protection est médiée par l’expression de CX3CR1. L’allèle I249 du gène Cx3cr1, à l’origine d’une augmentation des propriétés adhésives du couple CX3CR1/CX3CL1, est un facteur protecteur dans la survenue d’insuffisance rénale aiguë chez le malade atteint de sepsis. Collectivement, ces travaux confirment un rôle régulateur des monocytes inflammatoires au cours du sepsis et identifient de potentielles nouvelles cibles thérapeutiques. / Sepsis is the generalized inflammatory response secondary to an infection. This is a common and serious condition that involves the immune system. The action of innate immunity in sepsis is mediated by the activation and recruitment of monocytes, which are mononuclear circulating cells, which modulate the inflammatory process. The mobilization of monocytes involves chemotactic cytokines (chemokines) and their receptors. This work was specifically focused on the role of monocyte expression of chemokine receptors CCR2 and CX3CR1 in sepsis. To this end, we used mouse models of sepsis and analyzed the role of a common genetic polymorphism of CX3CR1 in a cohort of patients with sepsis.We have shown that in sepsis, monocytes’ motility was modified with an increase of their adhesion to vascular walls that was controlled in part by CX3CR1. We have also shown that inflammatory monocytes play a key role in the regulation of the inflammatory phenomenon in sepsis and that they protected the kidney from septic lesions via a CX3CR1 mediated adhesion mechanism. The I249 allele of CX3CR1, confering increased adhesive properties to monocytes, is a protective factor regarding the occurrence of acute kidney injury in septic patients. Collectively, these data confirm a a regulatory role for inflammatory monocytes during sepsis and identify potential new therapeutic targets.

Sepse e choque séptico são causas frequentes de morte nas unidades de terapia intensiva, sendo responsável pelo alto custo global de internação, segundo DATA-SUS. Sabendo-se que o paciente diabético apresenta um maior risco de infecção e que 22% dos indivíduos com sepse apresentam diabetes, é de extrema importância o melhor entendimento da sua fisiopatologia no paciente diabético para que medidas intervencionistas sejam desenvolvidas, preservando vidas. O projeto buscou avaliar a sepse experimentalmente através do modelo de ligadura e perfuração do ceco (CLP - 2 perfurações) em ratos Wistar machos sadios e tornados diabéticos através da injeção endovenosa de aloxana (42 mg/kg, i.v., 10 dias). Além disso, buscamos avaliar se o tratamento com insulina alteraria as variáveis escolhidas. O trabalho avaliou parâmetros hematológicos e bioquímicos como uréia, creatinina, alanina aminotransferase (ALT), aspartato aminotransferase (AST) e fosfatase alcalina (FAL). Após 6 horas da realização da CLP foram coletados lavados broncoalveolares (LBA) e peritoneal (LPe) com o objetivo de estudar o perfil de citocinas através da dosagem das interleucinas (IL)-1β, IL-6, IL-10, fator de necrose tumoral (TNF)-α e cytokine-induced neutrophill chemoattractant (CINC)-1 e CINC-2, celularidade total e específica. Rim, pulmão e fígado foram coletados para análises morfológicas e da atividade da mieloperoxidase (MPO). Após 6 horas de CLP observamos que a hematimetria, hemoglobina, plaquetometria e celularidade do LBA não sofreram alterações nem após o tratamento com insulina. A sepse provocou diminuição da leucometria total nos animais diabéticos e controles, aumento da celularidade total do LPe com um predomínio de polimorfonucleares, que foi semelhante em ambos os grupos; aumento da concentração no LPe de IL-1β, IL-6, CINC-1, CINC-2 e IL-10; as concentrações do TNF-α permaneceram idênticas em ambos os grupos. Em relação aos marcadores hepáticos, foram observados que os animais diabéticos possuem os maiores valores de ALT, AST e FAL em relação ao grupo controle e já apresentavam uma disfunção morfológica de hepatócitos, porém, sem infiltrado neutrofílico. O tratamento com insulina reduziu os valores dessas enzimas em níveis próximos aos do controle. Dos marcadores renais, apenas a uréia sofreu aumento significativo nos animais diabéticos em relação aos controles, sendo exacerbada pela CLP. Alterações glomerulares, como capilares dilatados e redução do espaço de Bowman foram observadas nos animais com sepse, os quais não sofreram influência após o tratamento com insulina. Estes dados sugerem que a insulina teve um efeito hepato-protetor e que o padrão causado pela sepse nos animais controles e diabéticos não foi modificado pelo tratamento com insulina. / Sepsis and septic shock are common cause of death in intensive care units (ICU) and according to Brazilian DATA-SUS is one of the major causes of high cost hospitalization. Since diabetic patients have a higher risk of infection and represent approximately 22% of all the septic individuals, it is extremely important to understand the pathophysiology of sepsis in diabetic patients in order to develop interventional measure. The objective of this study is to evaluate the experimental sepsis model by cecal ligation and puncture (CLP 2 punctures) in Wistar healthy males rendered diabetic by intravenous injection of alloxan (42 mg/kg, i.v., 10 days). The study analyzed hematological and biochemical parameters such as urea, creatinine, alanine aminotransferase (ALT), aspartate aminotransferase (AST) and alkaline phosphatase (ALP). Furthermore, we studied how insulin treatment could modulate these parameters. After 6 hours of CLP bronchoalveolar (BAL) and peritoneal lavages (PeL) were collected and a cytokine profile was accessed: interleukin (IL)-1β, IL-6, IL-10, tumor necrosis factor (TNF)-α, cytokine-induced neutrophill chemoattractant (CINC)-1, CINC-2. Samples from kidney, lung and liver were collected for morphological analysis and for the measurement of myeloperoxidase activity (MPO). After 6 hours of CLP, red blood cell count, hemoglobin, platelet count, cytokine profile and cellularity of the BAL did not change. In addition, insulin treatment did not change these parameters. CLP caused a decrease in total leukocyte count in both groups diabetic and control rats. Moreover, this model induced a rise in total PeL cellularity with a predominance of polymorfonuclear cells, which was similar in both groups control and diabetic rats. In the PeL, proinflammatory cytokines such as IL-1β, IL-6, CINC-1, CINC-2 and the antinflammatory cytokine IL-10 were enhanced. The TNF-α concentrations remained similar in both groups. Hepatic markers inferring in hepatocyte dysfunction were higher in the diabetes-induced animals what was in part restored after insulin administration. Regarding renal markers, only urea levels were enhanced in diabetic rats and worsened after CLP induction. Morphological changes, such as capillary dilatation and reduced Bowman space was already observed in the kidney of animals with sepsis, insulin treatment did not corrected the values. These data suggest that insulin had a hepato-protective effect but further changes were not observed after insulin treatment.

Billions of cells die everyday as a result of normal tissue turnover, infection, trauma or injury. These dead cells are taken up, processed and presented to T cells by antigen presenting cells resulting in tolerance or immunity. Apoptotic cells induce tolerance; however, the precise mechanisms are still unknown. Previous studies have shown that direct infusion of apoptotic cells induce tolerance mediated by TRAIL-expressing CD8+ T cells. We hypothesized that immunologic tolerance induced by apoptotic cells is dependent on the activation status of apoptotic cells and mediated by direct killing of target cells by TRAIL-expressing CD8+ T cells. Three different experimental systems were used to elucidate the mechanisms by which apoptotic cells regulate immune responses. Using a classical system of tolerance induction, we examined the immunological consequence of intravenous (i.v.) delivery of ex vivo-generated naïve or activated apoptotic cells. Naïve apoptotic cells induced tolerance when injected i.v.; however, previously activated apoptotic cells induced immunity. Further analysis revealed a key role for CD154 in the tolerogenic or immunogenic nature of the naïve or activated apoptotic cells, respectively, as tolerance resulted after i.v. injection of either naïve or activated apoptotic CD154-/- cells, while co-injection of an agonistic anti-CD40 mAb with naïve apoptotic T cells induced robust immunity. The infusion of large numbers of apoptotic cells has limited physiological relevance, so the investigation of the influence of apoptotic cells on the immune system turned to another experimental tolerance model where soluble peptide antigen is injected systemically to induce the peripheral deletion of a population of antigen-specific T cells. Using this system, we investigated how apoptotic cells generated in vivo leads to T cell tolerance. Following adoptive transfer of OT-II cells, wild-type mice injected with soluble OVA323-339 became unresponsive to subsequent CFA/OVA immunization. Interestingly, Trail-/- or Dr5-/- mice developed robust immunity; even though all strains displayed peripheral deletion of OVA-specific T cells. Subsequent investigation found the mechanism of action of the CD8+ T cells was TRAIL-mediated deletion of the OVA-responsive T cells in a TCR-specific manner. The experimental systems used above have some clinical relevance but are still not physiologic. To study the impact of apoptotic cells in a physiologic setting, we took advantage of the medical condition sepsis, which is accompanied by massive apoptosis of multiple immune cell populations. Thus, the final set of experiments in this thesis examined the tolerance induced during sepsis using a clinically-relevant cecal-ligation and puncture (CLP) model that included a secondary bacterial infection. CLP-treated WT mice had a reduced ability to control the secondary bacterial infection, which was paralleled by suppressed T cell responses, compared to sham-treated WT mice. In contrast, CLP- and sham-treated Trail-/- and Dr5-/- mice were able to similarly control the bacterial infection and generated bacterial antigen-specific T cell responses. The ability of CLP-treated wild-type mice to control the secondary infection and generate T cell immunity could be restored by the administration of a blocking anti-TRAIL mAb. These results suggest the importance of TRAIL in the induction of sepsis-induced immune suppression, such that TRAIL neutralization may be a potential therapeutic target to restore cellular immunity in septic patients.

Neonatal sepsis is an important cause of neonatal morbidity and mortality. There are two distinct types of sepsis- early and late onset. Group B streptococcus and Listeria are the most common causes of early onset neonatal sepsis historically. Physicians select antibiotics for neonates with fever based on historically common bacterial pathogens such as GBS, Ecoli, Listeria, and Staphylococcal aureus. However, the landscape of bacterial pathogens causing sepsis and fever in neonates seems to be changing. This could potentially change the first choice of antibiotics for this susceptible population. In this case study, we will present early-onset sepsis in a late preterm infant due to Streptococcus pneumoniae as confirmed by blood culture. The only maternal risk factors present in this case for septicemia were delivery less than 37 weeks. Patient initially had respiratory distress at delivery and required CPAP for 3 days. On day 2 of life, cultures were taken due to acute deterioration. Ampicillin and Gentamycin were given to the patient for empiric coverage initially. On day 2 of antibiotics, cultures were reported positive. Patient’s antibiotics had to be altered at that time to cover the isolated organism. The patient was inadequately treated up until cultures were positive. This case raises the question if Ampicillin and Gentamycin remain the best choice for broad antibiotic coverage in neonates with possible sepsis.

No description available.