UMLS:C0243026 - FACTA Search

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Query: UMLS:C0243026 (sepsis)
52,417 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Leukocyte interactions with vascular endothelium are an initial step for leukocyte entry into infectious foci where endothelial selectins may play a key role. Infiltrating leukocyte is essential for bacterial clearance, suggesting that endothelial selectins would be important in host defense against microorganisms. To address this, E-, P-, and E/P-selectin-deficient mice (E(-/-), P(-/-), E/P(-/-)) and wild-type (WT) mice underwent cecal ligation and puncture (CLP). Neither leukocyte infiltration nor bacterial load in the peritoneum was altered in E(-/-), P(-/-), and E/P(-/-) mice compared to WT mice. However, E(-/-), P(-/-), and E/P(-/-) mice were resistant to the lethality induced by CLP. At the mechanistic level, E(-/-), P(-/-), and E/P(-/-) mice did not develop renal dysfunction, a possible cause of death during sepsis. The serum level of interleukin-13 in E(-/-), P(-/-), and E/P(-/-) mice that had undergone CLP was higher than that in WT mice, whereas levels of macrophage inflammatory protein-2, KC in serum, and KC in kidney were lower than those in WT mice. These experiments demonstrate that endothelial selectin-mediated leukocyte rolling is not required for leukocyte entry in septic peritonitis and that endothelial selectins may affect mice survival during sepsis by influencing the cytokine profiles.
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PMID:Mice genetically lacking endothelial selectins are resistant to the lethality in septic peritonitis. 1178 25

The effect of Staphylococcus aureus alpha toxin (alpha-toxin) on selectin-mediated neutrophil adhesion was investigated in polymorphonuclear leukocyte- (PMN) induced vasocontraction and endothelial dysfunction. Adherence of human PMNs to rat aortic endothelium increased significantly following stimulation of the endothelium with alpha-toxin (0.1, 0.5, and 1 microg/mL). This effect could be significantly attenuated by monoclonal antibodies directed against P-selectin or fucoidin, a carbohydrate known to block selectins. Unstimulated human PMNs (10(6)cells/mL) were added to organ chambers containing rat aortic rings stimulated with alpha-toxin (0.5 microg/mL). PMNs elicited a significant vasocontraction in alpha-toxin-stimulated, but not in control aortic, rings (142+/-12 mg versus 12+/-4 mg, P < 0.05). This PMN-induced vasocontraction was virtually blunted by pretreatment with MAb directed against P-selectin or fucoidin (P < 0.05). Endothelial function as assessed by endothelium-dependent vasorelaxation to acetylcholine was substantially inhibited after induction of PMN-induced vasocontraction in alpha-toxin-stimulated aortic rings. This endothelial dysfunction was reduced by P-selectin MAb or fucoidin. In contrast, endothelium-independent relaxation to sodium nitrite was not altered by PMN incubation, indicating that vascular smooth muscle function was unaffected. Thus, PMN-endothelial interaction following S. aureus a-toxin activation of the vascular endothelium is at least, in part, mediated by selectins. As a consequence, PMN-induced vasocontraction and endothelial dysfunction occur. Such mechanisms may be involved in microcirculation abnormalities encountered in sepsis or septic shock due to S. aureus infection.
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PMID:Staphylococcus aureus alpha toxin mediates polymorphonuclear leukocyte-induced vasocontraction and endothelial dysfunction. 1179 66

We determined the time-dependent effects of conditional expression of neutrophil inhibitory factor (NIF), a specific 41-kDa CD18 integrin antagonist, on the time course of NIF expression and lung PMN (polymorphonuclear leukocyte) infiltration and vascular injury in a model of Escherichia coli-induced sepsis in mice. Studies were made in mice transduced with the E-selectin (ES) promoter-NIF construct (using liposomes) in which the NIF cDNA was driven by the inflammation- and endothelial cell-specific ES promoter. We observed time-dependent expression of NIF in pulmonary vascular endothelium that paralleled the ES expression. Expression of both was evident at 1 h after E. coli challenge, peaked at 3-6 h, and returned to basal level within 48 h. We observed that increases in PMN uptake and transalveolar PMN migration induced by E. coli challenge were reversed in a time-dependent manner following NIF expression in mice. NIF expression also prevented the progression of lung vascular injury and edema formation following E. coli challenge. Thus the conditional expression of NIF using the ES promoter can reverse, in a time-dependent manner, lung PMN infiltration and vascular injury induced by gram-negative sepsis. The results support the model that initial engagement of CD18 integrins enables the further recruitment of additional PMN into lung tissues such that PMN continue to sequester and migrate after E. coli challenge.
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PMID:Time-dependent reversal of sepsis-induced PMN uptake and lung vascular injury by expression of CD18 antagonist. 1188 Mar 6

A central position in the development of systemic inflammation is played by activation of the vascular endothelium and monocyte- macrophage system. Both are associated with the formation of inflammatory cytokines, the primary mission of which is mobilization of the organism to cope with the infection. The so-called acute stage response develops with typical clinical manifestations and laboratory values. When it is impossible to stop the inflammation the syndrome of systemic inflammatory response develops with excessive activity of inflammatory cytokines and immune mechanisms. This apparently favourable system can be highly toxic for the organism and can lead to the syndrome of multiorgan failure, to disseminated intravascular coagulation, to depression of the myocardium, refractory vasodilatation, hypertension and septic shock. The compensatory antagonistic mechanism which develops due to the formation of anti-inflammatory cytokines leads sometimes to the development of a balanced state of immunity which is most favourable from the prognostic aspect. In case of their excess however immunodepression develops which is equally dangerous for the patient as excessive cytokine activity. From what has been said ensues the need of regular monitoring of patients with sepsis and thus also detailed investigation of their immune system.
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PMID:[Role of cytokines in the development of local and systemic inflammation and septic shock]. 1242 7

This review addresses our present-day knowledge on the role of different cellular adhesion molecules, cytokines and glycoproteins for the detection of sepsis-induced injury in the microvasculature of the human lung using immunohistochemistry. Through the induction and modulation of endothelial cell adhesion molecules, such as E-selectin (CD 62E), the vascular endothelium controls leukocyte extravasation into tissue. E-Selectin, not expressed by unstimulated endothelium, is activated by cytokines and initiates neutrophil recruitment in sepsis-induced lung injury. Since E-selectin is strongly expressed in the pulmonary microvasculature in sepsis-associated fatalities, the immunohistochemical detection of an intense expression of E-selectin in lung tissue is a valuable diagnostic tool in the forensic postmortem elucidation of death due to sepsis. VLA-4 (CD49d/CD29) is strongly expressed on intravascular, interstitial and intra-alveolar leukocytes in sepsis-associated fatalities, whereas in non-septic fatalities an irregular weak immunoreactivity can be observed on interstitial leukocytes and no positive immunohistochemical expression can be observed on intravascular or intra-alveolar leukocytes. ICAM-1 (CD54) is strongly expressed on endothelial cells of the pulmonary microvasculature and on pulmonary macrophages and lymphocytes in sepsis-associated fatalities. In contrast, an infrequent weak immunohistochemical reaction for ICAM-1 is found on pulmonary endothelium and on perivascular leukocytes in non-septic fatalities. The up-regulation of both cellular adhesion molecules can be considered as an useful immunohistochemical postmortem marker of sepsis. Lactoferrin (LF) is an iron-binding glycoprotein located in specific (secondary) granules of leukocytes and plays a central role in the host response to infectious stimuli in providing both bacteriostatic and bactericidal protection. There is a statistically significant association between an enhanced expression of LF on pulmonary leukocytes in sepsis-related fatalities in contrast to non-septic controls. The immunohistochemical detection of an enhanced expression of LF can contribute to the postmortem discrimination between sepsis and non-septic fatalities. Application of carbohydrate-specific lectins (ConA, UEA, GSA I, GSA II, MPA, PNA, Jac, WGA, MAA, LPA, SNA) on deparaffinated lung tissue sections from sepsis-associated fatalities and control cases results to some extent in different staining patterns of alveolar epithelial cells and subepithelial seromucous glands of the bronchi. Apart from differences in binding sites for alpha-mannose, N-acetyl-neuraminic acid and alpha-(2-6)-galactose (as detected by different expression for ConA, MAA and SNA), the main finding is that no binding sites for alpha-N-acetyl-galactosamine (as investigated by MPA immunoreactivity) can be detected on alveolar epithelial cells and mucous parts of subepithelial seromucous glands in sepsis cases in contrast to the presence of such binding sites in controls. Since most intracellular pathogens persist in macrophages and epithelial cells during infection, it is likely that these pathogens contribute to a continual deprivation or consumption, respectively, of glycoproteins physiologically secreted by alveolar epithelial and glandular cells at different time points and stages of infection and may, among other mechanisms, by reducing pathogen clearance amplify the inflammatory response. Vascular endothelial growth factor (VEGF), an angiogenic and chemotactic peptide, is abundantly expressed in normal lung tissue, especially in alveolar and bronchial epithelium, glandular cells of the bronchi, and activated alveolar macrophages. Pulmonary VEGF immunostaining differs in sepsis when compared to healthy individuals. In the latter a preponderant strong VEGF immunoreaction can be found on alveolar epithelium (predominately type II pneumocytes), bronchial epithelium and glandular cells of the bronchi and bronchioli, and activated alveolar macrophages. In contrast, in sepsis no VEGF immunopositivity can beivity can be observed on bronchial epithelium or glandular cells of the bronchi and bronchioli, and no or relatively sparse VEGF immunoreactivity is found on alveolar epithelial cells. The precise mechanisms of the decreased pulmonary VEGF expression in septic patients under conditions of intensive care medicine are not clear at present. During the complex cascade of excessive pro-inflammatory and anti-inflammatory mediator release involved in the host's systemic inflammatory response in the development of sepsis-induced lung injury, VEGF expression may be suppressed in sepsis by a hitherto not identified agent or the interaction of different mediators of cellular inflammation. For the detection of sepsis-induced lung injury the aforementioned markers can be used sufficiently, e.g. to give immunohistochemical evidence of a previously undiagnosed sepsis and to confirm or rule out a presumed diagnosis of a sepsis-associated fatality. The employment of the presented immunohistochemical methods will be particularly helpful when macroscopical and routine histological autopsy findings in cases of suspected fatal sepsis are unspecific or unconvincing, respectively, and clinical data on the patient's previous history are not available. Referring to the forensic argumentation regarding causality on the subject of possibly fatal septic complications, e.g. in the sequel of diagnostic or therapeutic iatrogenic injection procedures or being relevant to pressure sore-associated fatalities, aetiopathogenetic conclusions can be optimized on the basis of the described micromorphological investigations.
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PMID:Immunohistochemical detection of sepsis-induced lung injury in human autopsy material. 1293 35

The development of potent drugs to treat cardiopulmonary failure in sepsis, such as antibiotics and new immunomodulatory therapeutic approaches have not prevented sepsis from being a major health problem. Dysfunction of the vascular endothelium is an early event in septic shock. The recognition of endothelium-derived substances, such as nitric oxide and endothelin, important mediators of systemic inflammatory response syndrome, led to the proposal that pharmacological inhibition of nitric oxide and endothelin production could represent a useful strategy in the treatment of septic shock. Splanchnic ischemia and translocation of endotoxin from the gut to the circulation contributes significantly to the high mortality rate in sepsis-related syndromes. This vasoconstriction in the splanchnic circulation can be partially blocked by inducible nitric oxide synthase inhibitor aminoguanidine or endothelin receptor antagonist bosentan in experimental models of septic shock. It can be suggested that endothelin and nitric oxide may affect survival. Although septic shock is a highly complex pathophysiological state, the course of septic shock has different phases with different characteristics which need different (special) treatment strategy. The inhibition of nitric oxide production during hyperdynamic, earlier phase of sepsis combined with the blockade of endothelin receptors at a later stage during the hypodynamic, late phase appears to be a novel promising strategy for the therapy of septic shock. The aim of this review is to discuss the role of nitric oxide and endothelin in sepsis and the potential therapeutic implications of blockade of nitric oxide and endothelin as a target in treatment of human septic shock. Briefly the importance of timing of intervention is also emphasized.
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PMID:Effects of endothelin and nitric oxide on organ injury, mesenteric ischemia, and survival in experimental models of septic shock. 1453 35

Binding of host inflammatory cells to the endothelium is a critical contributor to the vascular damage characteristic of severe meningococcal disease and is regulated by endothelial cell adhesion molecules such as ICAM-1, VCAM-1 and CD62E. Intact meningococci induce far higher levels of CD62E than lipopolysaccharide (LPS) alone, whereas LPS is at least as potent as meningococci at inducing both VCAM-1 and ICAM-1 expression. This suggests that meningococci possess additional factors other than LPS present in whole bacteria that result in differential adhesion molecule expression. To investigate this possibility, we studied the capacity of an LPS-deficient isogenic strain of serogroup B Neisseria meningitidis H44/76 (lpxA-) to induce endothelial cell adhesion molecule expression and translocation of the transcription factor NF-kappaB, and compared it to both parent and unencapsulated strains of both B1940 and H44/76 and purified LPS. Although the LPS-deficient isogenic mutant of strain H44/76 was found to be a poor inducer of NF-kappaB, it induced higher levels of CD62E expression than LPS alone. These data provide evidence that intact meningococci induce a range of signals in the endothelium that are distinct from those seen with purified LPS alone and that they occur in a LPS-dependent and LPS-independent manner. These signals may explain the potent effects of N. meningitidis on CD62E expression on vascular endothelium and provide a basis for the complex endothelial dysregulation seen in meningococcal sepsis.
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PMID:High-level endothelial E-selectin (CD62E) cell adhesion molecule expression by a lipopolysaccharide-deficient strain of Neisseria meningitidis despite poor activation of NF-kappaB transcription factor. 1467 68

The virulence of pathogenic bacteria is critically dependent on their ability to produce toxins that attack eukaryotic target cells. Microbial toxins are either structural components of the bacterial cell wall (endotoxins) or actively secreted proteins (exotoxins). Sepsis and septic shock, which represent major causes of mortality in modern intensive care medicine, are caused by an inadequate inflammatory and immunological host response to bacterial infection. Emerging evidence suggests that the systemic spread of microbial toxins, rather than bacteremia itself, is the crucial event in the pathogenesis of this dramatic dysregulation. The endothelium, with its diversity of physiological functions is a main target of bacterial toxins. The resulting endothelial dysfunction is believed to contribute to the underlying pathomechanisms and the collapse of homeostasis of organ function. In vitro, bacterial toxins induce subtle alterations of endothelial cell function rather than massive cell damage. Furthermore, bacterial toxins targeting endothelial cells severely alter the behavior of extravascular cells and circulating leukocytes via excessive formation of vasoactive mediators and overexpression of adhesion molecules. Research on the effects of microbial toxins on vascular endothelium has broadened our general understanding of microbial strategies to induce organ damage, even in the absence of viable bacteria. Combining antitoxin strategies with antibiotic therapy may prove to be of benefit to patients suffering from bacterial sepsis in the future.
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PMID:Endothelial responses to bacterial toxins in sepsis. 1470 Feb 71

Inflammation is a complex process regulated by a cascade of cytokines and growth factors. This review summarizes the emerging evidence implicating activin A and follistatin in the inflammatory process. Our recent studies have highlighted that activin A is released early in the process as part of the circulatory cytokine cascade during acute systemic inflammation. This release occurs concurrently with tumor necrosis factor (TNF)-alpha and prior to that of interleukin (IL)-6 and follistatin. Although, the cellular source(s) of activin A are yet to be established, circulating blood cells and the vascular endothelium are candidates for this rapid release of activin A into the circulation. The release of activin A and follistatin is also observed in the clinical setting, in particular in sepsis. Furthermore activin A is released into cerebrospinal fluid in a model of meningitis in rabbits. The role of activin A in the inflammatory response is poorly understood, however, in vitro data has highlighted that activin A can have both pro- and anti-inflammatory actions on key mediators of the inflammatory response such as TNF-alpha, IL-1beta and IL-6. Furthermore, emerging data would suggest that activin A induction is restricted to certain types of inflammation and its release is dependant upon the inflammatory setting.
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PMID:Activin A and follistatin in systemic inflammation. 1545 76

Arginine appears to be a semiessential amino acid in humans during critical illness. Catabolic disease states such as sepsis, injury, and cancer cause an increase in arginine utilization, which exceeds body production, leading to arginine depletion. This is aggravated by the reduced nutrient intake that is associated with critical illness. Arginine depletion may have negative consequences on tissue function under these circumstances. Nutritional regimens containing arginine have been shown to improve nitrogen balance and lymphocyte function, and stimulate arginine transport in the liver. We have studied the effects of stress mediators on arginine transport in vascular endothelium, liver, and gut epithelium. In vascular endothelium, endotoxin stimulates arginine uptake, an effect that is mediated by the cytokine tumor necrosis factor-alpha (TNF-alpha) and by the cyclo-oxygenase pathway. This TNF-alpha stimulation involves the activation of intracellular protein kinase C (PKC). A significant increase in hepatic arginine transport activity also occurs following burn injury and in rats with progressive malignant disease. Surgical removal of the growing tumor results in a normalization of the accelerated hepatic arginine transport within days. Chronic metabolic acidosis and sepsis individually augment intestinal arginine transport in rats and Caco-2 cell culture. PKC and mitogen-activated protein kinases are involved in mediating the sepsis/acidosis stimulation of arginine transport. Understanding the regulation of plasma membrane arginine transport will enhance our knowledge of nutrition and metabolism in seriously ill patients and may lead to the design of improved nutritional support formulas.
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PMID:Arginine transport in catabolic disease states. 1546 94

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