Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: UMLS:C0243026 (sepsis)
 52,417 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Human blood coagulation factor XII (FXII; 80 kDa) contains a C-terminal serine protease zymogen domain, which becomes activated upon contacting a negative surface. Activated FXII (alphaFXIIa) brings about reciprocal activation of FXII and kallikrein that by further hydrolysis produces the free catalytic domain (betaFXIIa; 28 kDa). Increased levels of alphaFXIIa are associated with coronary heart disease, sepsis, and diabetes. Biophysical investigation of the structural basis of activation, substrate specificity, and regulation of FXII requires an efficient bacterial system for producing the wild-type and mutant recombinant proteins. Here, the cDNA of the zymogen domain of FXII (betaFXII) was cloned into the pET-28a(+) vector and the plasmid was transformed into Escherichia coli strain BL21 (DE3) and overexpressed. The multi-disulfide, recombinant protein, His(6)-betaFXII (rbetaFXII), expressed as an inclusion body, was purified by means of a Ni(2+)-charged resin. The matrix-bound rbetaFXII was subjected to refolding with the glutathione redox system and activated by the in vivo activator, kallikrein. The active form, rbetaFXIIa, obtained in milligram quantities, exhibited similar structural and comparable functional properties relative to human betaFXIIa, as indicated by circular dichroism spectroscopy and kinetics of substrate hydrolysis. Thermodynamics of enzyme:inhibitor complex formation, including the expected 1:1 stoichiometry, was determined for rbetaFXIIa by isothermal calorimetric titration with a specific recombinant protein inhibitor, Cucurbita maxima trypsin inhibitor-V (rCMTI-V; 7kDa).
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PMID:Expression, refolding, and activation of the catalytic domain of human blood coagulation factor XII. 1250 96

Therapeutic application of the serpin C1-inhibitor (C1-Inh) in inflammatory diseases like sepsis, acute myocardial infarction and vascular leakage syndrome seems promising, but large doses may be required. Therefore, a high-yield recombinant expression system for C1-Inh is very interesting. Earlier attempts to produce high levels of C1-Inh resulted in predominantly inactive C1-Inh. We describe the high yield expression of rhC1-Inh in Pichia pastoris, with 180 mg/l active C1-Inh at maximum. On average, 30 mg/l of 80-100% active C1-Inh was obtained. Progress curves were used to study the interaction with C1s, kallikrein, coagulation factor XIIa and XIa, and demonstrated that rhC1-Inh had the same inhibitory capacity as plasma C1-Inh. Structural integrity, as monitored via heat stability, was comparable despite differences in extent and nature of glycosylation. We conclude that the P. pastoris system is capable of high-level production of functionally and structurally intact human C1 inhibitor.
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PMID:Recombinant human C1-inhibitor produced in Pichia pastoris has the same inhibitory capacity as plasma C1-inhibitor. 1275 49

The hemodynamics of septic shock after endotoxinemia is influenced by the plasma kallikrein/kinin and the renin angiotensin systems. In recent years, new information has improved understanding of the protein/biologically active peptide interactions between these two systems. The plasma kallikrein/kinin system, more commonly known as the contact system, has undergone a re-evaluation as to how it assembles on cell membranes for physiological and pathophysiological activation and as to its role in Gram-negative sepsis. It has been proposed that it counterbalances the plasma renin angiotensin system. Furthermore, more knowledge about the renin angiotensin system has become available on how it either opposes the actions of the kallikrein/kinin system or, in some cases, summates with it. Understanding the interactions between these two systems may lead to development of better pharmacological treatments for endotoxin-induced shock.
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PMID:The plasma kallikrein/kinin and renin angiotensin systems in blood pressure regulation in sepsis. 1502 19

Our present study aimed to characterize the effects of lipopolysaccharide (LPS) on the expression of the bradykinin B2-receptor in the mouse heart, which may have a role in cardiac depression during sepsis. We found that LPS induced the up-regulation of B2-receptor mRNA in the heart in vivo and in cultured cardiac myocytes in vitro. Like LPS, tumor necrosis factor-alpha (TNF-alpha) but not interleukin (IL)-1-beta, IL-6 or endothelin-1 stimulated B2-receptor expression in cultured myocytes. The effect of LPS on the expression of B2-receptor mRNA was also mimicked in cardiac myocytes by Ang II via Ang II type 1 (AT1-) receptor. Losartan, an AT1-receptor antagonist, inhibited about 50% of the LPS-induced up-regulation of B2-receptor mRNA in the heart in vivo and in cultured cardiac myocytes in vitro. Furthermore, the up-regulation of B2-receptor mRNA by either LPS or Ang II in cultured myocytes was abolished by anti-TNF-alpha antibody. These results suggest that the up-regulation of cardiac B2-receptor expression by LPS is mediated through TNF-alpha, which is produced in the myocardium by two different mechanisms in an AT1-receptor-dependent and independent manners, implying the role of the cardiac kallikrein-kinin system in the development of cardiac dysfunction during sepsis.
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PMID:The lipopolysaccharide-induced up-regulation of bradykinin B2-receptor in the mouse heart is mediated by tumor necrosis factor-alpha and angiotensin II. 1675 7

The majority of ischaemia related injury occurs upon tissue reperfusion. Knock-out mouse models have recently shed light on the underlying molecular mechanisms, and suggest that this may be the result of an innate autoimmune response. Based on these new findings we present a novel model of immune redundancy and duality in reperfusion injury. Natural antibody, mannan-binding lectin and toll-like receptor 4 are three pre-formed innate immune receptors that recognise pathogenic molecular patterns. Removing either significantly ameliorates reperfusion injury. We propose that these three receptors serve as key parallel recognition elements that respond to the same or similar ischaemic neo-antigens, of which at least one may have a lipopolysaccharide-like motif. This would fit both with the ligand preference of the three receptors, and the observation that giving monoclonal antibody to lipopolysaccharide reduces reperfusion injury. The consequent injury caused by receptor activation appears to be mainly related to the complement anaphylatoxins, and less to phagocytes, oxidative radicals, and the membrane attack complex. C5a levels in particular are predictive of overall injury, and we suggest this anaphylatoxin causes most of reperfusion injury via both direct toxic effects and a generalised immune activation. The former is illustrated by the recent observation that excess C5a alone can cause cardiac dysfunction. As for the latter, there is evidence that adaptive immunity (especially CD4+ cells) and other serum cascades (coagulation and kallikrein) are involved, and may have been recruited by complement. Furthermore, excess C5a can cause innate immune overactivation that paralyses neutrophils, reduces complement lytic function, and leads to systemic inflammation. This is analogous to what happens in sepsis, and would explain the passive role in IRI of normal immune effectors. Finally, there is a duality complement's function in reperfusion, as some elements are conductive of damage, whilst others may help inflammatory resolution. Most important among the latter are the opsonins, like C3b and apparently C1q, which help macrophages clear apoptosing cells before they undergo secondary necrosis. This model has important implications for clinical interventions. Firstly, redundancy means that inhibiting multiple receptors may achieve a larger mortality reduction than the small and inconsistent one seen in the published monotherapy trials. Secondly, duality means that a non-specific inhibition of complement would reduce both injury and resolution. Therefore, a specific inhibition of the lectin pathway and/or an inhibition of the downstream effectors upon which the receptors converge (e.g. C5a) seem to be a better interceptive strategy.
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PMID:A novel interpretation of immune redundancy and duality in reperfusion injury with important implications for intervention in ischaemic disease. 1716 98

Lipopolysaccharides at approximate plasma reactivities >3 ng/mL or beta-glucans at >0.5-1 Amicrog/mL are toxic for human blood; lipopolysaccharide interacts with membrane components of susceptible cells (eg, monocytes) activating phospholipase A(2) that destroys the cell membrane. Cell fragments (microparticles or DNA) possess polynegative niches that activate intrinsic hemostasis. Pathologic disseminated intravascular coagulation arises. Blood vessels are obstructed by disseminated thrombi, and vital organ areas become ischemic. Multiorgan failure threatens life of the patient. Diagnosis and therapy of pathologic disseminated intravascular coagulation is of extreme clinical importance. For early diagnosis of pathologic disseminated intravascular coagulation, specific activation markers of coagulation (eg, plasmatic amidolytic thrombin activity) or the plasmatic lipopolysaccharide or glucan reactivity can be measured. A new treatment target might be kallikrein or factor XIIa; 10 to 20 mM arginine is the approximate 50% inhibitory concentration against the contact phase of coagulation. The complex interaction between cell fragments and hemostasis causes pathologic disseminated intravascular coagulation in sepsis.
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PMID:Coagulation activation by lipopolysaccharides. 1816 May 70

This study examines alterations in the plasma proteome in ten adults affected by sepsis caused by Acinetobacter baumannii as compared to paired healthy controls. 2-DE profiles of plasma from patients and paired healthy donors, depleted of the six most abundant proteins, were analysed by the DIGE technique. Protein spot detection and quantification were performed with the Differential In-gel Analysis and Biological Variation Analysis modules of the DeCyder() software. Differentially expressed proteins were identified by mass spectrometry (MALDI-TOF/TOF) after colloidal Coomassie blue staining. Almost 900 spots were detected on a unique 2-D gel by the DIGE technique. A total of 269 protein spots of differential abundance were shown to be statistically significant (2.5-fold) with p values of p< or =0.01 (135 spots) and p< or =0.05 (134 spots) as determined by the t test. Seventy-one spots were submitted to mass spectrometry and about 30% could be successfully identified. This multiplex approach significantly reduced experimental variability, allowing for the confident detection of small differences in protein levels. Results include differentially expressed lipoproteins as well as proteins belonging to inflammatory/coagulation pathways and the kallikrein-kinin system. These data improves the knowledge for future developments in sepsis diagnosis, staging and therapy.
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PMID:Differential proteomics of the plasma of individuals with sepsis caused by Acinetobacter baumannii. 1978 74

Hemostasis is a sensitive and tightly regulated process, involving vascular endothelium and blood cells, as well as factors of the coagulation and fibrinolytic cascades. In severe and invasive infectious diseases, the equilibrium between the procoagulant and anticoagulant status of the host may change dramatically and can induce life-threatening complications. A growing body of evidence suggests that the contact system, also known as the intrinsic pathway of coagulation or kallikrein/kinin system, participate in these processes. Contact activation leads to the release of the highly potent proinflammatory peptide bradykinin and initiates the intrinsic pathway of coagulation. Several studies have shown a systemic activation of the contact system in animal models of severe bacterial infections, and similar findings were also reported when monitoring patients suffering from sepsis, severe sepsis, or septic shock. Complications resulting from a systemic activation of the contact system are pathologically high levels of bradykinin, consumption of contact factors, and a subsequent induction of inflammatory reactions. These conditions may contribute to serious complications such as hypotension and vascular leakage. Here, we summarize the state of the art in this field of research with a focus on the contact system, and we also discuss a potential role for the contact system as a target for the development of novel antimicrobial strategies.
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PMID:Contact system activation in severe infectious diseases. 2023 12

C1 inhibitor (C1INH) is a serpin that regulates both complement and contact (kallikrein-kinin) system activation. It consists of a serpin domain that is highly homologous to other serpins and an amino terminal non-serpin mucin-like domain. Deficiency of C1INH results in hereditary angioedema, a disease characterised by episodes of angioedema of the skin or the mucosa of the gastrointestinal tract or the oropharynx. Although early data suggested that angioedema was mediated via complement system activation, the preponderance of the data indicate that bradykinin is the mediator. In the past few years, it has become apparent that C1INH has additional anti-inflammatory functions independent of protease inhibition. These include interactions with leukocytes that may result in enhanced phagocytosis, with endothelial cells via E- and P-selectins that interfere with leukocyte rolling and in turn results in suppression of transmigration of leukocytes across the endothelium, and interactions with extracellular matrix components that may serve to concentrate C1INH at sites of inflammation. In addition, C1INH suppresses gram negative sepsis and endotoxin shock, partly via direct interaction with endotoxin that interferes with its interaction with macrophages, thereby suppressing tumour necrosis factor-a and other inflammatory mediators. C1INH treatment improves outcome in a number of disease models, including sepsis and other bacterial infections, possibly malaria, ischaemia-reperfusion injury (intestinal, hepatic, muscle, cardiac, brain), hyper-acute transplant rejection, and other inflammatory disease models. Recent data suggest that this effectiveness is the result of mechanisms that do not require protease inhibition, in addition to both complement and contact system activation.
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PMID:C1 inhibitor, a multi-functional serine protease inhibitor. 2080 8

Aeromonas species are Gram-negative facultative anaerobic bacteria found ubiquitously in a variety of aquatic environments and most commonly implicated as causative agents of gastroenteritis. Sepsis is a fatal complication of Aeromonas infectious diseases, particularly in immune-compromised patients. Two species, Aeromonas hydrophila and Aeromonas sobria, are associated with human disease. Feasible virulence factors of Aeromonas include fimbrial and afimbrial adhesion molecules, hemolysins, enterotoxins, lipases and proteases. Recently, we purified a 65-kDa A. sobria serine protease (ASP) from the culture supernatant of A. sobria and found that the enzyme induces vascular leakage and reduces blood pressure through activation of the kallikrein/kinin system. This ASP activity potentially contributes to the onset of septic shock, suggesting ASP as an important virulence factor. In this review, I describe both the substrate specificity and the structural property of ASP. Furthermore, I also discuss the maturation mechanism of ASP. Further studies will facilitate development of novel drugs for bacterial infection that have inhibitory effects on various serine proteases.
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PMID:[Structural and functional analysis of the serine protease from Aeromonas sobria]. 2212 76


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