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PubMed2005

Inflammation, complement activation and endothelial function in stable and unstable coronary artery disease.

BACKGROUND: Endothelial dysfunction plays an important role in the pathogenesis of coronary artery disease (CAD). Apart from traditional risk factors complement activation and inflammation may trigger and sustain endothelial dysfunction. We sought to assess the association between endothelial function, high sensitivity C-reactive protein (hs-CRP) and markers of complement activation in patients with either stable or unstable coronary artery disease. METHODS: We prospectively recruited 78 patients, 35 patients with stable angina pectoris (SAP) and 43 patients with unstable angina pectoris (UAP). Endothelial function was assessed as brachial artery reactivity (BAR). Hs-CRP, C3a, C5a and C1-Inhibitor (C1 inh.) were measured enzymatically. RESULTS: Patients with UAP showed higher median levels of hs-CRP and C3a compared to patients with SAP, while BAR was not significantly different between patient groups. In UAP patients, hs-CRP was significantly correlated with cholesterol (r=0.27, p<0.02), C3a (r=0.32, p<0.001) and C1 INH.(r=0.41, p<0.003), but not with flow mediated dilatation (r=0.09, P=0.41). Hs-CRP and C1 INH.were found to be independent predictors of UAP in a backward stepwise logistic regression model. CONCLUSIONS: We conclude that both hs-CRP, a marker of inflammation and C3a, a marker of complement activation are elevated in patients with UAP, but not in patients with SAP.

Aged↗
PubMed1993

C1 inhibitor.

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Amino Acid Sequence↗
PubMed1987

Isolation and analysis of immune complexes from sera of patients with polymyalgia rheumatica and giant cell arteritis.

Serum samples were obtained from patients with polymyalgia rheumatica (PMR: n = 10) or giant cell arteritis (GCA; n = 7), or both. Samples were taken either before treatment or within one week of starting prednisolone. Immune complexes (IC) were concentrated by polyethylene glycol (PEG) precipitation then purified with either IgG anti-C1q-Sepharose or IgG anti-C3c-Sepharose. Complex components were separated by sodium dodecyl sulphate (SDS) gradient polyacrylamide gel electrophoresis then transferred to nitrocellulose by Western blotting. Identification of proteins was carried out using specific antisera. All the IC contained IgM (mu chain), some contained IgA (alpha chain), and IgG (gamma chain). C1r, C1s, C1q, C3, C4, and C reactive protein (CRP), where tested, were found in most but not all IC. The occurrence of properdin, factor B, alpha 2 macroglobulin (alpha 2M), factor H (beta 1H), C1 esterase inhibitor, and C4 binding protein was also investigated. Immune complexes in PMR and GCA differed from those previously characterized in rheumatoid arthritis (RA)1 purified by anti-C1q-Sepharose which contained immunoglobulins and C1q only. No properdin or factor B were detected in RA IC purified with either anti-C1q-Sepharose or anti-C3c-Sepharose.

Aged↗
PubMed1990

Two-domain structure of the native and reactive centre cleaved forms of C1 inhibitor of human complement by neutron scattering.

The C1 inhibitor component of human complement is a member of the serpin superfamily, and controls C1 activation. Carbohydrate analyses showed that there are seven O-linked oligosaccharides in C1 inhibitor. Together with six N-linked complex-type oligosaccharides, the carbohydrate content is therefore 26% by weight and the molecular weight (Mr) is calculated as 71,100. Neutron scattering gives an Mr of 76,000 (+/- 4000) and a matchpoint of 41.8 to 42.3% 2H2O, in agreement with this carbohydrate and amino acid composition. Guinier plots to determine the radius of gyration RG were biphasic. Neutron contrast variation of C1 inhibitor in H2O-2H2O mixtures gave an overall radius of gyration RG at infinite contrast of 4.85 nm, from analyses at low Q, and a cross-sectional RG of 1.43 nm. The reactive centre cleaved form of C1 inhibitor has the same Mr and structure as the native molecule. The length of C1 inhibitor, 16 to 19 nm, is far greater than that of the putative serpin domain. This is attributed to an elongated structure for the carbohydrate-rich 113-residue N-terminal domain. The radial inhomogeneity of scattering density, alpha, is large at 59 x 10(-5) from the RG data and 28 x 10(-5) from the cross-sectional analysis, and this is accounted for by the high oligosaccharide content of C1 inhibitor. The scattering data were modelled using small spheres. A two-domain structure of length 18 nm based on two distinct scattering densities accounted for all the contrast variation data. One domain is based on the crystal structure of alpha 1 antitrypsin (7 nm x 3 nm x 3 nm). The other corresponds to an extended heavily glycosylated N-terminal domain of length 15 nm, whose long axis is close to the longest axis of the serpin domain. Calculation of the sedimentation coefficient s0(20),w for C1 inhibitor using the hydrodynamic sphere approach showed that a two-domain head-and-tail structure with an Mr of 71,000 and longest axis of 16 to 19 nm successfully reproduced the s0(20),w of 3.7 S. Possible roles of the N-terminal domain in the function of C1 inhibitor are discussed.

Borohydrides↗
PubMed1984

Enzymatic inactivation of human plasma C1-inhibitor and alpha 1-antichymotrypsin by Pseudomonas aeruginosa proteinase and elastase.

Two major human plasma proteinase inhibitors, C1-inhibitor and alpha 1-antichymotrypsin, were enzymatically inactivated by Pseudomonas aeruginosa elastase and proteinase. Incubation of C1-inhibitor with the Pseudomonas enzymes at inhibitor/enzyme molar ratios of 1000:1 (elastase) or 22:1 (proteinase) resulted in cleavage of the 104 kDa intact inhibitor to an 89 kDa intermediate which retained full inhibitory activity against plasmin and plasma kallikrein. The intermediate was then cleaved to an 83 kDa inactive product. The initial non-inactivating cleavage of C1-inhibitor occurred in a region of the molecule readily accessible to limited proteolysis by both enzymes. The inactivating cleavage, however, occurred more readily with the elastase. alpha 1-Antichymotrypsin was inactivated by P. aeruginosa proteinase and elastase by limited proteolysis at inhibitor/enzyme molar ratios of 14 000:1. The 64 kDa intact inhibitor was cleaved to form an inactive 60 kDa product, and a low molecular mass peptide fragment was observed. No stable enzyme-inhibitor complexes were detected, and no random proteolysis of the inactivated inhibitors was noted, even after prolonged incubation. Catalytic inactivation of C1-inhibitor and alpha 1-antichymotrypsin by P. aeruginosa proteinase and elastase may contribute to the tissue damage and hemorrhagic lesions which occur during pseudomonal infections.

Chymotrypsin↗
PubMed1992

Type II hereditary angio-oedema associated with two mutations in one allele of the C1-inhibitor gene around the reactive-site coding region.

The polymerase chain reaction and nucleotide sequence analysis have been used to characterise two point mutations in the eighth exon of one allele of the C1-inhibitor gene in a kindred with type II hereditary angio-oedema (HAE). The mutations comprise a G to A substitution at C1-inhibitor gene nucleotide 16789 and an upstream C to T substitution at nucleotide position 16765. This represents the first report of these two mutations in the same C1-inhibitor allele in type II HAE. The molecular genetic pathogenesis of HAE is discussed in the light of these findings.

Alleles↗
PubMedDate not supplied

A point mutation in the C1-inhibitor gene causes type I hereditary angiooedema.

The polymerase chain reaction and nucleotide sequencing have been used to characterise a single base substitution (CAG-->TAG at nucleotide 16842 in the C1-inhibitor gene in the affected members of a single family with type I C1-inhibitor deficiency. This mutation creates the TAG translation termination codon, thereby truncating the C1-inhibitor C-terminus by 17 amino acids. The effects of the mutation are discussed.

Amino Acid Sequence↗
PubMed1986

Human C1 inhibitor: primary structure, cDNA cloning, and chromosomal localization.

The primary structure of human C1 inhibitor was determined by peptide and DNA sequencing. The single-chain polypeptide moiety of the intact inhibitor is 478 residues (52,869 Da), accounting for only 51% of the apparent molecular mass of the circulating protein (104,000 Da). The positions of six glucosamine-based and five galactosamine-based oligosaccharides were determined. Another nine threonine residues are probably also glycosylated. Most of the carbohydrate prosthetic groups (probably 17) are located at the amino-terminal end (residues 1-120) of the protein and are particularly concentrated in a region where the tetrapeptide sequence Glx-Pro-Thr-Thr, and variants thereof, is repeated 7 times. No phosphate was detected in C1 inhibitor. Two disulfide bridges connect cysteine-101 to cysteine-406 and cysteine-108 to cysteine-183. Comparison of the amino acid and cDNA sequences indicates that secretion is mediated by a 22-residue signal peptide and that further proteolytic processing does not occur. C1 inhibitor is a member of the large serine protease inhibitor (serpin) gene family. The homology concerns residues 120 through the C-terminus. The sequence was compared with those of nine other serpins, and conserved and nonconserved regions correlated with elements in the tertiary structure of alpha 1-antitrypsin. The C1 inhibitor gene maps to chromosome 11, p11.2-q13. C1 inhibitor genes of patients from four hereditary angioneurotic edema kindreds do not have obvious deletions or rearrangements in the C1 inhibitor locus. A HgiAI DNA polymorphism, identified following the observation of sequence variants, will be useful as a linkage marker in studies of mutant C1 inhibitor genes.

Amino Acid Sequence↗
PubMed1994

In vitro activation of the classical pathway of complement by a streptococcal lipoteichoic acid.

The purpose of this study was to find whether a glycerolphosphate-containing lipoteichoic acid prepared from Streptococcus sobrinus OMZ 176 cells would activate the classical pathway of complement while in solution. Reference activators were lipopolysaccharide from Escherichia coli 0111:B4 and heat-aggregated immunoglobulin G. Serum samples were taken from healthy students. Analysis through crossed immunoelectrophoresis showed that lipoteichoic acid caused an almost complete dissociation of the C1qrs macromolecule. All activators decreased the area of and slowed the electrophoretic mobility of the C4 protein peaks, with lipoteichoic acid causing the most pronounced alterations. Electroimmunoassays showed that lipoteichoic acid separately, yielded detectable amounts of free C1r2s2 subunits; it also generated significantly more trimer complexes between C1r, C1s and C1 inhibitor (C1INH) than did the other two activators. Lipoteichoic acid was, however, a comparatively weak inducer of tetramer C1INH-C1r-C1s-C1INH complexes. Analysis through Western blotting showed that all activators accelerated consumption of C1r, induced complex formations between C1INH and C1s and produced cleavage products of C2. Altogether, the immunochemical analysis gave clear evidence of classical pathway activation by lipoteichoic acid, but its activation profile differed from those seen with lipopolysaccharide and aggregated immunoglobulin G.

Analysis of Variance↗
PubMed1987

The influence of serum from patients infected with Mycoplasma pneumoniae on the osmotic property of normal human erythrocytes.

Venous blood sera from children infected with Mycoplasma pneumoniae (MP) responded with a high titer to MP antibodies, affected healthy normal erythrocytes in vitro, and gave rise to changes in erythrocyte osmotic fragility. When serum was inactivated at 56 degrees C for 30 min or preincubated with anti-human C1 esterase inhibitor, the changes in the osmotic properties were suppressed at the lower level. The total sialic acid content and the intracellular ATP concentration of the treated erythrocytes were analyzed.

Adenosine Triphosphatases↗
PubMed1996

Role of complement in the aetiology of Pick's disease?

Complement in the postmortem brains of 15 cases of Pick's disease has been widely analyzed immunohistochemically and, in 2 cases, by immunoelectron microscopy. Astrocytes and the Pick bodies and cytoplasm of ballooned neurons were immunoreactive with antibodies to classical pathway components C1, C1q, C4, C2 and C3 and the terminal complex components C5, C6 and C8. In almost all cases, no immunostaining was obtained with antibodies against C9 and neoepitopes in the membrane attack complex (MAC), the complement complex responsible for cytotoxicity. However, unequivocal staining with antibodies to two soluble complement regulatory proteins, S-protein and clusterin, and to the membrane complement inhibitor CD59 was found, although three other membrane inhibitors, CR1(CD35), DAF (CD55), and MCP (CD46), were not detected. The complement immunoreactivity of astrocytes and neurons could be the result of complement biosynthesis or attack. Complement attack will be restricted by the expressed regulatory proteins. However, neurons may be the victims of attack since they show pathological change. The internalization of complement-attacked membrane, perhaps involving the genesis of Pick bodies and ballooning, may explain the intracellular immunolocalization of complement in damaged neurons. Immunoglobulins, as a possible source of complement activation, were observed in only two cases, leaving unresolved the trigger for complement activation in the other cases.

Aged↗
PubMed1984

Interaction between C1-INA, coagulation, fibrinolysis and kinin system in hereditary angioneurotic edema (HANE) and urticaria.

The C1-inactivator plays an important role not only in the initial phases of the complement system, but also in those of the coagulation, fibrinolysis and kinin systems. The present study was concerned with the reciprocal influence of decreased C1-inactivator levels in patients with hereditary angioneurotic edema (HANE, HAE). In 13 HANE-I patients there were significantly increased levels of the coagulation factors XII, XI, V, of plasminogen and of alpha 2-antiplasmin, while the factors IX and VII were decreased. Conversely, it emerged that in patients with markedly raised prephase factor levels, angioneurotic edema occurred in the presence of normal or only slightly decreased C1-inactivator levels. However, the ratio between factor XI and C1-INA activity was significantly higher than in normal and urticaria patients. Factor XII, HMWK, XI, VIII and V levels were significantly raised in 10 patients with frank chronic urticaria, while factor VII was lowered. Numerous other factors and inhibitors of the coagulation, fibrinolysis and kinin systems were, however, normal or showed no significant differences.

Angioedema↗
PubMed1984

Activation of blood coagulation, fibrinolytic and kallikrein systems during storage of plasma.

This study deals with the question of how blood coagulation, kallikrein and fibrinolytic systems are affected by storage of plasma at +6 degrees C. Blood was collected into citrate phosphate dextrose adenine (CPD) or acid citrate dextrose (ACD) and the plasma samples were stored at +6 degrees C for 35 days. Samples were taken at weekly intervals for assays of various parameters of the different systems. No significant changes were observed in the levels of the main thrombin inhibitor, antithrombin III. At the end of the storage period, however, fibrinopeptide A levels increased markedly, particularly in the ACD plasma, indicating thrombin activation. There was no change in the plasminogen level, but a decrease in the levels of antiplasmin and urokinase inhibitors and an increase in the level of the fibrinogen degradation fragment B beta 15-42 were observed, indicating activation of the fibrinolytic system. The level of antikallikrein activity decreased sharply in ACD plasma; CPD plasma was less affected. This decrease was parallel to the increase in spontaneous proteolytic activity and correlated with the increase in fibrinopeptide A. Prolonged storage of plasma of +6 degrees C thus resulted in the activation of coagulation, fibrinolytic and kallikrein systems and decrease in inhibitors. The activation was much more pronounced in ACD than in CPD plasma.

Anticoagulants↗
PubMed1993

Protease-antiprotease levels and whole-blood chemiluminescence in acute peritonitis.

Whole-blood chemiluminescence and levels of leukocyte proteases and plasma protease inhibitors were studied in 43 patients with acute, generalized peritonitis. An almost three-fold increase in whole-blood chemiluminescence was found in acute peritonitis, which may indicate activation or "priming" of the leukocytes by blood-borne factors. High levels of leukocyte elastase and neutrophil proteinase 4(3) were found in plasma and peritoneal exudate. Patients with sepsis had higher plasma levels of both proteases than other patients. Large variations in the plasma levels among patients decreased their sensitivity as markers of infectious complications during the postoperative period. The plasma levels of the protease inhibitors followed three different patterns of reaction. The acute phase proteins alpha 1-proteinase inhibitor and C1-inactivator, increased during the first week of disease, to normalise later in its course. alpha 2-macroglobulin, antithrombin III and alpha 2-antiplasmin were all decreased from onset and normalised later in the course, while secretory leukocyte protease inhibitor showed a slow decrease throughout the course of disease. In peritonitis exudate, the levels of the main protease inhibitors, alpha 1-Proteinase Inhibitor and alpha 2-Macroglobulin, were decreased, probably due to complexation and subsequent elimination, as a part of the defense against liberated leukocyte proteases. The immunoreactive and especially functional levels of the protease inhibitors alpha 2-Antiplasmin, Antithrombin III and C1-Inactivator were also decreased in the exudate, indicating an increased turn-over of these proteins through activation of the cascade systems and/or break-down by leukocyte proteases. In contrast to the other inhibitors, secretory leukocyte protease inhibitor showed higher levels in exudate than in plasma, and unexpectedly high exudate/plasma-quotients were seen in cases with colonic perforations. Degradation of complement factor 3 (C3) and decreased "opsonic capacity" were found in exudate. The "opsonic capacity" could be correlated to the levels of leukocyte proteases in the exudate, which indicates that degradation of complement factor 3 may have been at least partly due to the action of leukocyte proteases. Further depletion of complement factors in exudates of long-standing peritonitis or abscesses may create a vicious circle of deficient opsonisation and clearance of bacteria, as earlier reported for chronic pleural exudates.

Acute Disease↗
PubMed1977

Hereditary angioneurotic edema (HANE): Lack of close linkage between HLA haplotypes and C1 esterase inhibitor deficiency.

The HLA haplotypes were defined in a series including 11 patients with hereditary angioneurotic edema (HANE), five symptom-free subjects with pathological laboratory findings characteristic of HANE, and their 33 healthy kinsmen. The subjects belonged to two Finnish families representing the more common form of HANE which is recognized by the immunochemically observed decrease of the inhibitor (C1-INH) blocking the esterase activity of the first complement component. No linkage between HANE and the HLA system was found.

Adolescent↗
PubMed1996

Heterologous complementation of a Rieske iron-sulfur protein-deficient Saccharomyces cerevisiae by the Rip1 gene of Schizosaccharomyces pombe.

A cDNA carrying the Rip1 gene, which encodes the Rieske iron-sulfur protein of Schizosaccharomyces pombe, has been cloned by complementing the respiratory deficiency of a Saccharomyces cerevisiae strain in which the endogenous copy of the RIP1 gene has been deleted. The deduced amino acid sequences of the S. pombe and S. cerevisiae iron-sulfur proteins are 50% identical, with the highest region of identity being in the C termini of the proteins, where the 2Fe:2S cluster is bound. When expressed in the S. cerevisiae deletion strain, the S. pombe iron-sulfur protein restores 25-30% of the ubiquinol-cytochrome c reductase activity. The kinetics of cytochrome c reduction, the effects of inhibitors which act at defined sites in the cytochrome bc1 complex, and the optical properties of cytochrome b in membranes from the S. cerevisiae deletion strain complemented with S. pombe iron-sulfur protein indicate that the S. pombe protein interacts with cytochrome b to restore an apparently normal ubiquinol oxidase site, but that interaction between the iron-sulfur protein and cytochrome c1 is partially impaired. This is the first heterologous replacement of an electron transfer protein in a respiratory enzyme complex in S. cerevisiae.

Amino Acid Sequence↗
PubMed1990

Interferon gamma increases in vitro and in vivo expression of C1 inhibitor.

C1 inhibitor (C1 INH) is the major protease inhibitor of the first components of the classic complement system and of the proteases of the Hageman factor pathways. Since C1 INH may modulate inflammatory reactions associated with complement and contact system activation, we sought to determine if the cytokine gamma interferon (IFN-gamma) could modulate C1 INH production. Initial studies investigated the effect of IFN-gamma on the molecular and protein expression of C1 INH in human erythroleukemia (HEL) cells. HEL cells constitutively expressed the 2.1 kb mRNA for C1 INH. IFN-gamma (50 to 1,000 U/mL), but not interferon alpha or beta, increased twofold the amount of C1 INH mRNA expressed within HEL cells. Similarly, this cytokine increased HEL cell C1 INH synthesis of a 105 Kd protein 10-fold, from 1.9 +/- 0.5 microgram C1 INH antigen per 10(8) cells (mean +/- SEM) to 19 +/- 8 micrograms/10(8) cells in 8 days. C1 INH produced by HEL cells after IFN-gamma stimulation had fully intact kallikrein neutralizing activity. Moreover, conditioned media of IFN-gamma-treated HEL cells accumulated more secreted C1 INH in 8 days (6.7 micrograms/mL/10(8) cells) than untreated cells (0.6 microgram/mL/10(8) cells). Additional studies were done on plasma specimens from 22 patients with metastatic colorectal carcinoma who received IFN-gamma daily for 4 days by intravenous infusion. Before treatment, the mean +/- SEM C1 INH levels in these patients was 438 +/- 16 micrograms/mL. At day 10 from the start of the infusion, the plasma C1 INH in these patients increased to 586 +/- 32 micrograms/mL (P less than .0001). The extent of rise of plasma C1 INH after IFN-gamma treatment was independent of dose from 0.01 to 40 U/m2. After 30 days, the mean plasma C1 INH levels decreased to 502 +/- 27 micrograms/mL. These combined studies indicate that IFN-gamma can increase C1 INH protein expression in vitro and in vivo.

Blotting, Northern↗