A fisiopatologia do choque séptico caracteriza-se por uma produção excessiva de mediadores inflamatórios, dentre eles o óxido nítrico (NO), conduzindo a uma hipotensão prolongada associada a um aumento inicial de vasopressina (AVP) e uma diminuição na fase tardia. A ketamina é um anestésico com propriedades cardioestimulatórias e anti-inflamatórias. O presente trabalho testou a hipótese de que a ketamina, através de suas propriedades anti-inflamatórias no choque séptico, teria uma ação inibitória sobre a síntese do óxido nítrico, favorecendo a liberação de AVP e preservando a função cardiovascular. O choque endotoxêmico foi induzido através de uma injeção i.v. de 1,5 mg/kg de lipopolissacarídeo (LPS) em ratos Wistar adultos machos. Após a injeção de LPS, um grupo de animais foi tratado com ketamina (10 mg/kg) e o grupo controle recebeu salina. A administração de LPS produziu uma queda significativa da pressão arterial média (PAM) (p<0,01) associada a um aumento da freqüência cardíaca (FC) (p<0,01). Essas alterações foram acompanhadas por uma elevação significativa nas concentrações plasmáticas de AVP após duas horas (p<0,01), seguida de queda nas próximas horas, e por uma elevação nas concentrações de NO plasmático (p<0,01). Quando o LPS foi combinado à administração i.v. de ketamina, observou-se uma atenuação da hipotensão (p<0,01) e uma potencialização na liberação de AVP (p<0,01) pelo LPS. No entanto, a produção de NO após a adminstração da ketamina não mostrou diferença em relação ao LPS, indicando não ser esta a via utilizada pela ketamina. Para verificar o papel da ativação simpática na preservação da função cardiovascular pela ketamina no choque endotoxêmico, utilizou-se um inibidor simpático central, a moxonidina (MOXO). O pré-tratamento i.v. com MOXO (50 µg /Kg) atenuou significativamente o aumento da FC produzido pela ketamina (p < 0,05) apenas na segunda e quarta horas, porém com ação não significativa sobre a PAM. Estes dados sugerem um efeito cardioestimulatório da ketamina no choque séptico principalmente por uma potencialização na liberação da AVP e esta parece não se dar pela via do NO / The pathophysiology of septic shock is characterized by excessive production of inflammatory mediators, including nitric oxide (NO), leading to a prolonged hypotension associated with an initial increase of vasopressin (AVP) and a late phase decrease. Ketamine is an anesthetic with cardiostimulatory and anti- inflammatory properties. The present study tested the hypothesis that ketamine, through its anti-inflammatory properties in septic shock, have an inhibitory effect on the synthesis of nitric oxide, promoting the release of AVP and preserving cardiovascular function. Endotoxemic shock was induced by an iv injection of 1.5 mg / kg lipopolysaccharide (LPS) in adult male Wistar rats. After LPS injection, a group of animals was treated with ketamine (10 mg / kg) and the control group received saline. The LPS administration produced a significant decrease in mean arterial pressure (MAP) (p <0.01) associated with an increase in heart rate (HR) (p <0,01). These changes were accompanied by significant increases in plasma AVP after two hours (p <0.01), followed by fall in the coming hours, and plasma NO increasing (p <0.01). When LPS was combined with iv ketamine administration, there was an attenuation of hypotension (p <0.01) and an enhancement in the release of AVP (p <0.01) by LPS. However, the production of NO after ketamine adminstration showed no difference compared to LPS, indicating this is not the route used by ketamine. To verify the role of sympathetic activation in ketamine\'s preservation of cardiovascular function in endotoxemic shock, used a central sympathetic inhibitor, moxonidine (moxo). Pretreatment with moxo iv (50 µg / kg) significantly attenuated the increase in HR produced by ketamine (p <0.05) only in the second and fourth hour, but with no significant action on the MAP. These data suggest that the cardiostimulatory effect of ketamine in septic shock primarily occurs by potentiation of AVP release, and this does not seem to give the NO pathway

Acidose metabólica é um fenômeno comum e clinicamente significativo em pacientes com sepse grave ou choque séptico. Entretanto, sua composição não é bem estabelecida. Neste estudo, descrevemos a composição da acidose metabólica em pacientes com sepse grave ou choque séptico desde sua internação em unidade de terapia intensiva (UTI) até os quinto dia de internação em unidade de terapia intensiva (UTI). Na admissão à UTI, a acidose metabólica foi um fenômeno muito freqüente. Ela era composta principalmente pelo componente derivado dos íons inorgânicos (dado principalmente pela diferença sódio cloro), seguido em magnitude pelo componentes decorrentes de ânions não mensuráveis e lactato e atenuada por hipoalbuminemia. A magnitude da acidose metabólica e hipercloremia foram maiores entre os pacientes não-sobreviventes (considerando a mortalidade hospitalar). Em análise multivariada o grau de acidose por íons inorgânicos, além do escore de gravidade APACHE II e nível inicial de creatinina sérica, esteve associada a mortalidade hospitalar. Ao longo do período de estudo, os pacientes sobreviventes apresentaram melhora da acidose metabólica por diminuição dos níveis de ânions não-mensuráveis e lactato. Os não sobreviventes mantiveram a mesma magnitude de acidose metabólica e apresentaram queda do pH por aumento da PCO2 / Metabolic acidosis is frequently found in patients with severe sepsis and septic shock. Several studies have shown that the amount of metabolic acidosis measured by the standard base excess (SBE) at hospital admission and its evolution throughout the first days of intensive care unit (ICU) stay are correlated with clinical outcome. However, the precise composition of the metabolic acidosis in patients with severe sepsis and septic shock is not well known. In this study, we have described the composition of metabolic acidosis in patients with severe sepsis or septic shock at ICU admission and throughout the first five days of ICU stay, by applying the quantitative physicochemical methodology. Metabolic acidosis was extremely frequent at admission to the ICU. Its main component was attributable to the inorganic ion difference disturbance (mainly determined by the Na Cl difference), followed in magnitude by unmeasured anions and lactate´s components. Hypoalbuminemia represented the most frequent and important alkalinizing component. The degree of metabolic acidosis and hyperchloremia was more pronounced in the non-survivors group (according to hospital mortality). In a multivariate analysis the degree of metabolic acidosis due to disturbances in innorganic ion difference was associated to hospital mortality. Acidosis in survivors was corrected during the study period due to a decrease in lactate and SIG levels, whereas non-survivors did not correct their metabolic acidosis and suffered a decrease in the pH due to an increase in PCO2 levels

Objectives: Negative energy balance can impair regeneration of the respiratory epithelium and limit the functionality of respiratory muscles, which can prolong mechanical ventilation. The present study sought to quantify and identify deviation in energy requirements of patients with septic shock during and upon liberation from mechanical ventilation. Methods: Patients admitted into intensive care with initial diagnosis of septic shock and mechanical ventilation-dependent were recruited. Their metabolic requirements before and after liberation from mechanical ventilation were measured by indirect calorimetry. Paired t-test was used to examine the variance between the two modes of breathing and Spearman rho correlation coefficient to examine relationship of selected indicators. Results: Thirty-five patients, 20 males and 15 females mean age 69 ±10 years, body height of 1.58 ±0.08 meters, and ideal body weight 59.01 ±7.63 kg were recruited. Median APACHEII score was 22, length of stay in the intensive care was 45 ±65 days and duration on mechanical ventilation was 24 ±25 days. Measured energy expenditure during ventilation was 2090 ±489 kcal∙d-1 upon liberation from ventilation was 1910 ±579 kcal∙d-1, and actual caloric intake was 1148 ±495 kcal∙d-1. Paired-t test showed that measured energy expenditure (p=0.02), actual calories provision and energy expenditure with (p=0.00) and without (p=0.00) ventilator support were all significantly different. Mean carbohydrate oxidation was 0.17 ±0.09 g·min-1 when patients were on mechanical ventilation compared to 0.14 ±0.08 g·min-1 upon liberalization from it, however, the results were not statistically significant. Furthermore, mean lipid oxidation was 0.08 ±0.05 g·min-1 during mechanical ventilation and 0.09±0.07 g·min-1 upon liberalization from it and the mean difference was not statistically significant. Spearman correlation coefficient showed a positive relationship between actual calorie provision and duration of stay in intensive care (r=0.41 and p=0.01) and duration on mechanical ventilation (r=0.55 and p=0.00). Oxygen consumption (r=0.49 and p=0.00) and carbon dioxide production (r=0.4 and p=0.02) were moderately strong and positive during and upon liberation from mechanical ventilation. Correlation between lipid oxidation and oxygen consumption during ventilation (r=0.74, p=0.00) and after ventilation (r=0.82, p=0.00) as well as lipid oxidation and carbon dioxide production during ventilation (r=0.37, p=0.03) and liberation from ventilator (r=0.91, p=0.00) were significantly correlated with each other in grams per minute only. Conclusions: This is a pioneering study to examine energy expenditure and substrate utilization and oxidation within a single cohort of patients. The lower measured energy expenditure upon liberation from mechanical ventilation among critically ill patients could result from positive pressure support from ventilation, the repeated cycle of “rest” and “work” during weaning from ventilators and the asynchronization between self-initiated breathing effort and the ventilatory support. The positive relationship in duration on mechanical ventilation and length of stay with calorie consumption could be longer stay led to more time for progression to reach nutrition targets. . Any discrepancy in energy expenditure and substrate utilization with and without ventilatory support should be monitored. Future studies are important to examine whether matching energy expenditure with energy intake could promote positive clinical outcomes.

Coordenação de Aperfeiçoamento de Pessoal de Nível Superior / Ao longo dos últimos anos, apesar de todo desenvolvimento e pesquisa, a mortalidade na sepse permanece elevada. Na área de microcirculação foram realizados estudos em modelos experimentais de sepse ao longo das últimas duas décadas, quando se observou, através de técnicas invasivas, alterações como redução expressiva da densidade capilar funcional. A técnica denominada sidestream dark field (SDF) imaging, recentemente desenvolvida, permite a avaliação da microcirculação de forma transcutânea. A utilização desta técnica permitiu evidenciar a redução da densidade capilar funcional em pacientes com sepse grave quando comparado a um indivíduo saudável. Posteriormente, foi demonstrado que alterações persistentes na microcirculação de pacientes sépticos, mesmo com sinais vitais estabilizados, estão associadas com pior prognóstico.Evidentemente, os pacientes com sepse grave ou choque séptico sofrem uma grande quantidade de intervenções terapêuticas, aonde muitas delas alteram a microcirculação. Estudos analisando a microcirculação em pacientes em uso de nitroglicerina, corticóide, recebendo hemotransfusão ou ainda infusão de noradrenalina foram publicados recentemente.Entretanto, até o presente momento, não existem publicações que descrevam a influência dos sedativos na microcirculação de pacientes com choque séptico. As drogas mais comumente utilizadas para sedação de pacientes em ventilação mecânica são o sedativo midazolam e o anestésico propofol. Os objetivos do estudo foram: avaliar o efeito dos principais agentes sedativos utilizados na prática clínica na microcirculação de pacientes com choque séptico utilizando a técnica de sidestream dark field imaging, comparar os efeitos na microcirculação do midazolam com o propofol em pacientes com choque séptico e verificar se existe relação das alterações microcirculatórias provocadas pelos sedativos com as variações de diferentes parâmetros hemodinâmicos, gasométricos ou metabólicos como pressão arterial, índice cardíaco, lactato e saturação venosa central de oxigênio. Foram estudados (estudo prospectivo) 16 pacientes internados no Centro de Terapia Intensiva da Casa de Saúde São José. Os pacientes internados com diagnóstico de choque séptico e que possuíam indicação clínica de ventilação mecânica e de suspensão diária da sedação foram submetidos ao estudo da microcirculação na mucosa sublingual utilizando a técnica de sidestream dark field imaging. Estes pacientes foram sedados conforme orientação do protocolo já existente de sedação, inicialmente com propofol e posteriormente com midazolam. Os principais resultados observados foram:a macrohemodinâmica não diferiu nos 2 momentos do exame, o BIS (bispectral índex of sedation) se manteve na faixa recomendada nos 2 momentos do exame, tendo aumentado quando o paciente acordava, conforme esperado, e a proporção de vasos pequenos perfundidos e o índice de fluxo da microcirculação foram significativamente menores, enquanto o índice de heterogeneidade foi significativamente maior quando os pacientes estavam recebendo infusão de propofol quando comparados com a infusão de midazolam. Concluímos que, em pacientes com choque séptico, a administração de midazolam resulta em uma melhora dos parâmetros microcirculatórios quando comparada com a administração de propofol. Essa diferença não pode ser atribuída a alterações de variáveis hemodinâmicas sistêmicas. / Over the past few years, despite all research and development, mortality from sepsis remains high. In microcirculatory studies using experimental models of sepsis, and invasive techniques, significant reduction in functional capillary density were observed. The recently developed technique called sidestream dark field (SDF) imaging, allows transcutaneously evaluation of the microcirculation. This technique has demonstrated reduction on functional capillary density in patients with severe sepsis, when compared to healthy individuals. Subsequently, it was shown that even in septic patients with stabilized vital signs, persistent alterations in the microcirculation are associated with worse prognosis. Obviously, patients with severe sepsis or septic shock suffer a lot of therapeutic interventions, many of them affecting the microvasculature. Studies analyzing the microcirculation in patients using nitroglycerin, corticosteroids, receiving blood transfusion or infusion of norepinephrine were recently published. However, to date, no publications have described the influence of sedatives in the microcirculation of these patients. The most commonly drugs used for sedation of mechanically ventilated patients are midazolam and propofol. The main objectives of this study were to observe the effects of two sedative agents used in clinical practice in the microcirculation of patients with septic shock. The sidestream dark field imaging technique was used to compare the effects on microcirculation of midazolam with propofol in patients with septic shock and verify a relationship between microcirculatory changes caused by sedatives and different variations of hemodynamic parameters such as blood pressure, heart rate, lactate and central venous oxygen saturation.We have prospectively studied 16 patients admitted to the Intensive Care Unit of Casa de Saúde São José. Patients admitted with a diagnosis of septic shock and in need of mechanical ventilation were submitted to microcirculation analysis in the sublingual mucosa using sidestream dark field imaging technique. These patients were sedated according to the sedation protocol, initially with propofol, and later on with midazolam. The main results were: the macrohemodynamics did not differ during the two moments of examination; BIS (bispectral index of sedation) remained in the range recommended during both exams and increased when patients woke up, as expected, and finally, the proportion of small vessels perfused and microcirculatory flow index were significantly lower, while the heterogeneity index was higher, when patients were receiving propofol infusion in comparison with the midazolam one. We concluded that in patients with septic shock, midazolam administration results in an improvement of the microcirculation when compared with the administration of propofol and this difference could not be attributed to changes in systemic hemodynamic.

La réponse immuno-inflammatoire au cours du choc septique associe une importante réponse inflammatoire initiale responsable de l'état de choc et le développement secondaire d'altérations du système immunitaire. Les polynucléaires neutrophiles (PNN) jouent un rôle central dans la réponse immunitaire. Des données récentes de la littérature décrivent également un rôle immunosuppresseur jusqu'alors méconnu pour ces cellules. Nous avons exploré leur possible implication dans la physiopathologie du choc septique.Le but de ce travail était l'exploration des altérations phénotypiques, fonctionnelles et transcriptomiques des PNN lors de la phase immunosuppressive du choc septique. Nos résultats montrent une diminution de la capacité de migration des PNN ainsi qu'une diminution de la production de composés bactéricides (myéloperoxydase, lactoferrine) alors que la réponse aux cytokines et la phagocytose n'apparaissent pas altérées. Le contenu en myéloperoxydase et la présence de PNN immatures CD10dimCD16dim étaient indépendamment associés à une mortalité plus élevée. De manière intéressante, CD177 était le gène le plus différentiellement exprimé entre les patients et les volontaires sains. CD177 et CD10 étaient inversement corrélés. Ainsi, la diminution du chimiotactisme, la perte de myéloperoxydase, la présence de cellules immatures et leurs liens avec la mortalité pourraient contribuer au contexte d'immunosuppression présent chez les patients septiques. Au final, les pistes d'exploration futures convergent vers la population de PNN immatures et le rôle spécifique du CD177 dans les états septiques sévères / Severe septic syndromes deeply impair innate and adaptive immunity and are responsible for sepsis-induced immunosuppression. While neutrophils represent the first line of defense against infection, little is known about their phenotype and functions few days after sepsis, when the immunosuppressive phase is maximal (i.e., between day 3 and 8). The objective of this study was thus to perform a global evaluation of neutrophil alterations in immunosuppressed septic patients based on phenotypic, functional and transcriptomic studies. Our results highlight a markedly altered neutrophil chemotaxis (functional and chemokine receptor expressions), oxidative burst, lactoferrin content and an increased number of circulating immature granulocytes (i.e., CD10dimCD16dim). In contrast, phagocytosis and activation capacities were conserved. It is interesting to note that a diminished myeloperoxidase expression appeared as the best predictor to identify a group of septic shock patients at high risk of death. Similarly, patients with lower proportions of CD10dimCD16dim granulocytes had a significant better survival compared with patients presenting a higher percentage. CD177 mRNA, coding for an activation molecule in chemotaxis but also known to be overexpressed in immature cells, had the highest fold change modulation between patients and controls. Considering the potential dual roles of CD177 neutrophil (i.e., maturation / chemotaxis), its participation in septic shock pathophysiology deserves further investigation. To conclude, circulating neutrophils present with phenotypic, functional and morphological alterations few days after sepsis onset. These dysfunctions may participate in the deleterious role of sepsis-induced immunosuppression. The present results open new perspectives in the mechanisms favoring nosocomial infections after septic shock. They deserve to be further investigated in a larger clinical study and in animal models recapitulating these alterations

A sepse é caracterizada por uma produção excessiva de mediadores inflamatórios, acompanhada de taquicardia e hipotensão. Experimentalmente, a administração de endotoxina (Lipopolissacarídeo, LPS) em doses relativamente elevadas induz choque endotoxêmico, sendo um bom modelo de estudo da sepse. Diversos grupos têm demonstrado ações antiinflamatórias e antitumorais do citral, um composto do óleo essencial de Cymbopogon citratus. Nosso laboratório demonstrou ação antipirética do citral em modelo de febre induzida por LPS, acompanhada de redução nos níveis de citocinas plasmáticas e de prostaglandina E2 (PGE2) no plasma e área pré óptica do hipotálamo (POA), importante região termorregulatória. A hipótese testada neste trabalho foi a de que o citral atenua a hipotensão provocada pela endotoxina, além de amenizar as alterações termoregulatórias. Todos os procedimentos foram executados de acordo com os princípios éticos de experimentação animal, aprovados pelo comitê de ética local (CEUA 2015.1 1214 58-2). Foi realizado o implante de cânulas na artéria e veia femoral para registro da pressão arterial e administração de LPS (1,5 mg/kg) ou salina apirogênica 0,9% além do implante de datalogger na cavidade peritoneal de ratos Wistar, para registro da temperatura corporal. No dia do registro, 30 minutos antes da administração de LPS ou salina, os animais receberam citral (100 mg/kg) ou tween 80 a 1% (veículo) por via oral. Os parâmetros cardiovasculares e temperatura corporal foram registrados por 300 minutos após os respectivos tratamentos. Os valores de pressão arterial média (PAM) e frequência cardíaca (FC) foram coletados a cada 10 minutos após o tratamento e a temperatura corporal foi registrada pelo datalogger em intervalos de 5 minutos. Em outro protocolo foi realizado apenas o implante de cânula na veia femoral dos animais de todos os grupos para administração de LPS ou salina, coleta de sangue para dosagem de interleucina 6, PGE2, nitrito e nitrato e corticosterona e coleta do encéfalo para dosagem de PGE2 e PGD2. As diferenças estatísticas entre os grupos foram analisadas pelo teste ANOVA two-way seguido por pós teste de Newman-Keuls, com o nível de significância adotado de p < 0,05. A administração de LPS provocou queda na PAM eaumento na FC. Tais respostas não foram afetadas pela administração prévia de citral. O LPS também induziu febre e aumento nas concentrações plasmáticas de interleucina - 6 (IL-6), óxido nítrico (NO), PGE2 e corticosterona. Esses parâmetros não foram alterados pela pré- administração de Citral. No entanto, o citral provocou redução na produção de PGD2 naPOA, sem alterar a de PGE2 nesta região. Podemos concluir que o citral não previne as alterações nos parâmetros cardiovasculares no modelo de endotoxemia em ratos, porém reduz a produção de um mediador termorregulatório e inflamatório do sistema nervoso central (a PGD2), sem alterar a produção de outros mediadores inflamatórios a nível periférico (no plasma). Portanto, em um modelo mais agressivo de inflamação sistênica o citral não se mostrou suficiente para proteger o organismo das ações deletérias do LPS. / Sepsis is characterized by the overproduction of inflammatory mediators, accompanied by tachycardia and hypotension. Experimentally, administration of endotoxin (Lipopolysaccharide, LPS) in relatively high doses induces endotoxemic shock, a widely used model of sepsis in rats. Several groups have demonstrated anti-inflammatory and antitumor roles of citral, an essential oil compound of Cymbopogon citratus. Emilio-Silva et al. (2017) have shown an antipyretic role of citral in a model of LPS-induced fever, accompanied by a reduction of cytokines and prostaglandin E2 plasma levels and in the preoptic area of hypothalamus (POA), the hierarchically most important thermoregulatory region. We hypothesized that citral attenuates the LPS-induced hypotension, besides mitigating the thermoregulatory adjustments in rats. All procedures were performed in agreement with ethical guidelines for animal experimentation aproved by the local ethical committee (CEUA 2015.1 1214 58-2). Femoral artery and vein were implanted with cannulas for blood pressure recording and LPS (1.5 mg/kg) or 0.9% apyrogenic saline injection. In a second surgical procedure a datalogger was implanted into the peritoneal cavity for measurements of body temperature. All surgical procedures were performed under Ketamin/xilazin (100/10 mg/kg) anesthesia. One day after arterial catheterization, 30 minutes prior to LPS or saline administration, the animals received either citral (100 mg / kg) or 1% tween 80 (vehicle) oralstarly. The cardiovascular parameters and body temperature were recorded for 300 minutes after the respective treatments. Mean blood pressure (MAP) and heart rate (HR) were collected every 10 minutes after treatments and body temperature was recorded by the datalogger at 5 minute intervals. Blood samples were obtained in another set of rats for interleukin-6, PGE2, nitrite and nitrate and corticosterone analyses. The brain was removed for PGE2 and PGD2 analyses. Statistical differences between groups were analyzed by the two-way or one-way ANOVA test followed by Newman-Keuls post-test, with significance level adopted at p <0.05. As expected, LPS administration caused a decrease in MAP and an increase in HR, and these responses were not affected by citral. LPS also induced fever and increased plasma levels of interleukin - 6 (IL - 6), nitric oxide (NO), prostaglandin E 2 andcorticosterone. These parameters were also not altered by citral. On the other hand, citral caused a reduction in prostaglandin D2 concentration in the POA, but failed to alter PGE2 levels in this region. Our data are consistent with the notion that citral does not affect changes in cardiovascular and thermoregulatory parameters. Consistently, citral also caused no changes in both LPS-induced peripheral inflammatory mediators (in plasma) and in the POA, except PGD2. Therefore, in our model which mimetic a fairly critical situation, citral may not be sufficient to protect the organism from the deleterious actions of LPS. Financial support: FAPESP / CAPES.

Sepsis is associated with high mortality and morbidity. Immediate recognition and treatment is crucial to prevent complications that can be highly detrimental and cause a significant impact on the U.S. healthcare economy. Numerous studies have been conducted to improve patient outcomes and lower healthcare costs from sepsis and septic shock. Many of these studies were focused on exploring healthcare providers' knowledge and compliance to the Surviving Sepsis Campaign (SSC) guidelines. This study aimed to explore and identify barriers to the implementation of the sepsis bundles and strategies to enhance healthcare providers' adherence to these bundles. A systematic review of articles was conducted using the ACE Star Model of Knowledge Transformation. Studies such as randomized controlled trials (RTC's), systematic reviews, retrospective studies, and prospective observational studies conducted in Intensive Care Units (ICUs) within the past 10 years were utilized, guided by the American Association of Critical Care Nurses' (AACN's) grading system. Sources of evidence were obtained from PubMed, CINAHL, and GoogleScholar. The results of this study are aimed at helping support the evidence-based clinical practice among providers caring for patients with sepsis and septic shock in an ICU setting using evidence-based guidelines. The results of this study provide an opportunity for healthcare systems to relieve financial burdens from sepsis and thus contribute to pos

<p>This thesis aimed at studying mechanisms involved in control of tissue fluid homeostasis during inflammation.</p><p>The interstitial fluid pressure (P_IF) is of importance for control of tissue fluid balance. A lowering of P_IF <i>in vivo</i> will result in a transport of fluid from the circulation into the tissue, leading to edema. Loose connective tissues that surround blood vessels have an intrinsic ability to take up fluid and swell. The connective tissue cells exert a tension on the fibrous network of the tissues, thereby preventing the tissues from swelling. Under normal homeostasis, the interactions between the cells and the fibrous network are mediated by β1 integrins. Connective tissue cells are in this way actively controlling P_IF.</p><p>Here we show a previously unrecognized function for the integrin αVβ3, namely in the control of P_IF. During inflammation the β1 integrin function is disturbed and the connective tissue cells release their tension on the fibrous network resulting in a lowering of P_IF. Such a lowering can be restored by platelet-derived growth factor (PDGF) -BB. We demonstrated that PDGF-BB restored P_IF through a mechanism that was dependent on integrin αVβ3. This was shown by the inability of PDGF-BB to restore a lowered P_IF in the presence of anti-integrin β3 IgG or a peptide inhibitor of integrin αVβ3. PDGF-BB was in addition unable to normalize a lowered P_IF in β3 null mice. Furthermore, we demonstrated that extracellular proteins from <i>Streptococcus equi</i> modulated αVβ3-mediated collagen gel contraction. Because of the established concordance between collagen gel contraction <i>in vitro</i> and control of P_IF <i>in vivo</i>, a potential role for these proteins in control of tissue fluid homeostasis during inflammation could be assumed. Sepsis and septic shock are severe, and sometimes lethal, conditions. Knowledge of how bacterial components influence P_IF and the mechanisms for tissue fluid control during inflammatory reactions is likely to be of clinical importance in treating sepsis and septic shock.</p>

This thesis aimed at studying mechanisms involved in control of tissue fluid homeostasis during inflammation. The interstitial fluid pressure (PIF) is of importance for control of tissue fluid balance. A lowering of PIF in vivo will result in a transport of fluid from the circulation into the tissue, leading to edema. Loose connective tissues that surround blood vessels have an intrinsic ability to take up fluid and swell. The connective tissue cells exert a tension on the fibrous network of the tissues, thereby preventing the tissues from swelling. Under normal homeostasis, the interactions between the cells and the fibrous network are mediated by β1 integrins. Connective tissue cells are in this way actively controlling PIF. Here we show a previously unrecognized function for the integrin αVβ3, namely in the control of PIF. During inflammation the β1 integrin function is disturbed and the connective tissue cells release their tension on the fibrous network resulting in a lowering of PIF. Such a lowering can be restored by platelet-derived growth factor (PDGF) -BB. We demonstrated that PDGF-BB restored PIF through a mechanism that was dependent on integrin αVβ3. This was shown by the inability of PDGF-BB to restore a lowered PIF in the presence of anti-integrin β3 IgG or a peptide inhibitor of integrin αVβ3. PDGF-BB was in addition unable to normalize a lowered PIF in β3 null mice. Furthermore, we demonstrated that extracellular proteins from Streptococcus equi modulated αVβ3-mediated collagen gel contraction. Because of the established concordance between collagen gel contraction in vitro and control of PIF in vivo, a potential role for these proteins in control of tissue fluid homeostasis during inflammation could be assumed. Sepsis and septic shock are severe, and sometimes lethal, conditions. Knowledge of how bacterial components influence PIF and the mechanisms for tissue fluid control during inflammatory reactions is likely to be of clinical importance in treating sepsis and septic shock.

Bei Patienten mit ARDS führt eine selektive pulmonale Vasodilatation durch inhaltives NO (iNO) zu einer Shuntreduktion. Die zusätzliche Gabe eines selektiven pulmonalen Vasokonstriktors führt zu einer additiven Verbesserung der Oxygenierung. Die Anzahl der NO-Responder ist bei vorliegender Sepsis reduziert. Es ist bekannt, dass hemoglobin based oxygen carriers (HBOC) durch NO-Scavenging einen pulmonalarteriellen Druckanstieg bewirken und dass dieser Effekt durch iNO antagonisierbar ist. In dieser Arbeit wurde untersucht, ob eine generalisierte Vasokonstriktion durch ein HBOC die Effektivität einer iNO-Therapie in einem Modell von ARDS mit LPS-induziertem Schock erhöht. Hierzu wurde bei 40 narkotisierten und instrumentierten Ratten mittels VILI und alveolärer Lavage ein stabiles ARDS etabliert und anschließend 1,5mg/kg LPS i.v. verabreicht. Es wurden 4 Versuchsgruppen gebildet: 1) und 3) erhielten 5ml/h HES10%, 2) und 4) 5ml/h Hämoglobin-glutamer 200 (Oxyglobin HBOC 301), 3) und 4) erhielten anschließend iNO. Die bekannten hämodynamischen Effekte eines HBOC und die Reduktion dieses Blutdruckanstiegs durch iNO wurden erstmals im ARDS mit LPS-induziertem Schock nachgewiesen. Zum Versuchsende zeigte keine Gruppe eine signifikante Änderung des MAP im Vergleich zum Ausgangspunkt. Bei alleiniger iNO-Therapie fiel der RVP (36,2 [30,0; 41,1] vs. 30,6mmHg [18,4; 36,3], p<0,05) und der PaO2 stieg von 82,6 [65,1; 107,3] auf 176,5mmHg [89,4; 207,5] (p<0,05). Die Kombination aus HBOC und iNO zeigte einen nicht signifikanten Abfall des RVP (32,8mmHg [28,5; 47,2] vs. 29,4mmHg [17,6; 49,1]) und Anstieg des PaO2 (65,76mmHg [61,0; 86,6] vs. 86,8mmHg [54,2; 203,0]). Es ergab sich kein additiver Effekt auf die Oxygenierung, wie er für pulmonale Vasokonstriktoren beschrieben ist. Eine Ursache dafür könnte die hohe endogene NO-Produktion nach LPSGabe sein, sodass die NO-Scavanging Kapazität im kombinierten Modell nicht ausreicht. Zukünftig sollte untersucht werden, ob dieser Effekt mit einer höheren Dosierung des HBOC erreichbar ist.