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Results for “Complement C1 Inhibitor Protein”

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At least 253 records · Page 14Linked to original sources
PubMed1983

Effect of dehydroepiandrosterone on hereditary angioedema.

Hereditary angioneurotic edema (HAE) is a complement-related clinical disorder with a deficiency of the C1 esterase inhibitor protein. Eight patients with severe attacks of the disease were treated with the adrenal "androgen" dehydroepiandrosterone sulphate (DS). Steroid therapy for 3-28 months resulted in dramatic improvement in their clinical state and a moderate increase in the serum concentration of C1 inhibitor. There was a significant increase in the serum level of either unconjugated dehydroepiandrosterone (D) or of DS during treatment.

Adolescent↗
PubMed1992

Heterozygous alpha 1-antichymotrypsin deficiency may be associated with cold urticaria.

Proteins of the serpin family (serine protease inhibitor) control key steps in the inflammatory, coagulation and complement systems. C1-inhibitor deficiency predisposes to hereditary angioneurotic oedema, and other serpins control proteolytic enzymes that may cause complement activation or the forming of oedema. We investigated whether deficiency of proteins of the serpin family may predispose to cold urticaria and therefore screened 7 male patients with severe cold urticaria for the presence of deficiency alleles of some of the members of the serpin antiprotease family. There were no findings of C1-inhibitor, alpha 1-antitrypsin, alpha 2-antiplasmin, antithrombin III, tissue plasminogen activator inhibitor or thyroxine binding protein deficiency. The prevalence of heterozygous alpha 1-antichymotrypsin deficiency was significantly higher than expected (prevalence ratio 25.8 (95% confidence interval 6.0-112), p < 0.0001). This finding is in concert with previous studies that have shown lower mean levels of alpha 1-antichymotrypsin among patients with cold urticaria and suggests that heterozygous deficiency of this antiprotease, which controls neutrophil cathepsin G and mast cell chymase may predispose to cold urticaria. The present series is, however, small and the results need confirmation in larger materials.

Cold Temperature↗
PubMed1989

Synthesis and regulation of C1 inhibitor in human skin fibroblasts.

Proteins of the C1 complex, C1q, C1r, and C1s, of the classical pathway of complement activation are known to be synthesized in human skin fibroblasts. Using metabolic labeling with [35S]methionine, immunoprecipitation, and SDS-PAGE, we demonstrate that human skin fibroblasts synthesize and secrete C1 inhibitor with an apparent molecular mass of 78 kDa in the cell lysate and 102 kDa in the extracellular medium. This C1 inhibitor had the capacity to bind activated C1s. Fibroblasts synthesized 30- to 50-fold more C1 inhibitor than was synthesized in monocytes. As previously reported, fibroblasts also synthesized C1r and C1s. IFN-gamma, IFN-beta 1, and TNF had significant, but distinct, effects on synthesis of C1 inhibitor, C1r, and C1s. Incubation of the cells with IFN-gamma, 1000 U/ml, for 24 h induced increases in the synthesis of C1 inhibitor, C1r, and C1s by 4.2-, 1.9- and 1.6-fold, respectively. IFN-beta 1 had effects similar to IFN-gamma, although smaller in magnitude. TNF, 12.5 ng/ml, induced increases in the synthesis of C1 inhibitor, C1r, and C1s by 1.5-, 1.4- and 2.6-fold. IL-1, IFN-beta 2 (IL-6), and LPS did not affect synthesis of C1 inhibitor, C1r, or C1s. Fibroblasts are present in large amounts in most tissues. Synthesis of C1 inhibitor, C1r, and C1s by these cells could provide a source of these important proteins in body tissues. In addition, fibroblasts should be a good model for the in vitro study of genetic diseases involving the synthesis of these proteins.

Adult↗
PubMed1986

Isolation and analysis of a cDNA coding for human C1 inhibitor.

A cDNA coding for C1 inhibitor was isolated from a human liver lambda gt11 expression library and sequenced by the dideoxy method. The amino acid sequence deduced from the cDNA indicated that the insert was a partial clone coding for 310 amino acids including the reactive site present at the carboxyl end of the molecule. The reactive site corresponds to that previously reported by Salvesen et al. (J. Biol. Chem. 260, 2432, 1985). The cDNA also contained a stop codon of TGA, 264 nucleotides at the 3' noncoding region, and a polyadenylation signal sequence of AATAAA 15 nucleotides upstream from the poly(A) tail. The amino acid sequence flanking the reactive site of the inhibitor is homologous to other members of the superfamily of plasma serine protease inhibitors.

Amino Acid Sequence↗
PubMed1976

C1 subcomponent conplexes in normal and pathological sera studied by crossed immunoelectrophoresis.

Selected pathological sera gave three molecular species of C1s protein on crossed immunoelectrophoresis in the presence of calcium. C1s precipitates were obtained at the origin and in the beta1 and alpha2 regions. 12 normal sera gave C1s protein peaks at the origin and in alpha2 position. One of the normal sera also contained a small amount of the beta1 C1s protein. The C1s protein at the origin represented macromolecular C1. The alpha2 peak was a complex composed of C1 IA, C1s and C1r proteins. This complex was preformed in serum and did not show C4 cleaving activity. The molecular species in the beta1 region was shown to be a calcium-dependent complex of C1r and C1s, probably in proenzyme form. the C1r-C1s complex formed macromolecular C1 on addition of purified C1q to serum. During electrophoresis activation of C1 subcomponents was initiated by a mechanism involving CIr with generation of CIs activity in eluted fractions corresponding to the position of macromolecular C1 as well as in the beta region. The significance of beta1 C1s complexes or of alpha2 C1s complexes in normal and pathological sera was discussed.

Angioedema↗
PubMed1975

Phylogeny of complement components in non-human primates.

The antigenic properties and functional activities of complement components were analyzed in primates to determine their relative evolutionary development. The sera of eight different sub-human primate species were examined by double diffusion in agar and compared to a pool of human serum with rabbit and goat antisera to human complement components Clq, Cls, C4, C2 C3, C5, C6, C8, C9, properdin, factor B (B), and C1 inhibitor. There are no apparent antigenic differences in complement proteins between man and the apes except for C1q. Old world monkeys are antigenically deficient in Clq,C1s, C9, and variably deficient in C4, C3, and C8. New World monkeys are antigenically deficient in all components (measured) except C5, C6, and properdin factor B. Prosimians are antigenically deficient in all components. Functional analyses of complement components showed similar levels in man and primates, except in prosimians. There is a dissociation between hemolytic assays and antigenic analyses, suggesting that functional sites may be separate from antigenic sites.

Absorption↗
PubMed1982

Complement biosynthesis by the human hepatoma-derived cell line HepG2.

The human hepatoma-derived cell line, HepG2, synthesized and secreted functional complement proteins C1r, C1s, C2, C3, C4, C5, factor B, C1 inhibitor, C3b inactivator, a small amount of C6, and trace amounts of C8; but failed to produce detectable C1q, C7, or C9. Immunochemically, C2, C3, C4, C5, and B were isolated from culture medium as proteins with molecular sizes and subunit structures identical to the corresponding components isolated from serum. C2 and factor B from cellular lysates had slightly lower molecular weights than the corresponding proteins in culture medium. C3, C4, and C5 were detected as single chain precursor molecules in cellular lysates. These results demonstrate that human C5, like C3 and C4, is synthesized as a single chain precursor that is converted by limited proteolysis to the native two-chain molecule. It also establishes the precursor-product relationship for human pro-C4 and native C4, pro-C5, and native C5.

Carcinoma, Hepatocellular↗
PubMed1994

Large-scale preparation of highly purified human C1-inhibitor for therapeutic use.

A two-step chromatographic procedure has been developed to purify human C1-inhibitor from cryoprecipitate-poor plasma after removal of vitamin K-dependent proteins and antithrombin III. The procedure, which is fully compatible with modern plasma fractionation schemes, includes anion-exchange chromatography on DMAE-Fractogel EMD, viral inactivation by solvent-detergent treatment, adsorption on SO3-Fractogel EMD and viral removal by nanofiltration on 35- and 15-nm pore size membranes. Overall yields were about 45% and 58% for antigen and activity, respectively, providing 60-70 mg of highly purified inhibitor per litre of plasma. The purified inhibitor had a specific activity of 6.5 +/- 0.5 units/mg protein, representing a more than 400-fold increase in purity compared with plasma. C1-inhibitor purity with respect to total protein was greater than 80%. The main contaminant was complement component C3 which accounted for 4-10% of the total protein. Minor contaminants included low amounts of IgM, IgG, IgA, fibrinogen and albumin. Complement component C4 was undetectable. The purified inhibitor was stable throughout the purification process and for more than 24 h at room temperature after reconstitution of the freeze-dried material. Animal tests in rats and mice demonstrated that the C1-inhibitor concentrate was well tolerated at relatively high doses.

Animals↗
PubMed1987

[Formation of IgG antibodies to C1 inhibitor as the cause of life-threatening angioedema].

A clinical picture with recurrent (in some cases potentially fatal) edema of skin and internal organs based not on a hereditary C1 inhibitor deficiency, but an acquired loss of C1 inhibitor activity due to antibodies is described for the first time in two patients. The clinical symptoms commenced in middle age patients between 40 and 46 years old. Anti C1 antibodies of the IgG were found in both patients. Quantitatively, these C1 inhibitor protein was in the lower range of normal, whereas no inhibitor activity could be demonstrated functionally. The function of the complement components C1, C2 and C4 was greatly reduced. The therapeutic use of C1 inhibitor concentrate at a high doses (6 X 500 U) as well as administration of high-dose corticosteroids in several emergency situations was unsuccessful.

Adult↗
PubMed1983

Control of coagulation and fibrinolysis by plasma proteinase inhibitors.

The control of coagulation and fibrinolytic events appears to be primarily due to four plasma proteinase inhibitors, antithrombin III, C-1-esterase inhibitor, alpha-2-antiplasmin, and alpha-2-macroglobulin. Results to date indicate that antithrombin III controls the activity of both thrombin and Factor Xa, C-1-esterase inhibitor controls kallikrein and probably activated Hageman Factor (Factor XIIa), and alpha-2-antiplasmin controls plasmin activity. The role of alpha-2-macroglobulin is not clear since it does not appear to be a primary inhibitor of any of the above enzymes. However, it is probable that it serves two functions, first as a "transfer" agent for the rapid removal of proteinases from the circulation which have been first bound by antithrombin III, C-1-esterase inhibitor, or alpha-2-antiplasmin. The second function is probably that of a back-up inhibitor when the levels of the three important controlling plasma proteins become low. The role of other plasma inhibitors such as alpha-1-proteinase inhibitor, alpha-1-antichymotrypsin, and the inter-alpha-trypsin inhibitor in coagulation and fibrinolysis would appear to be minor since these proteins either do not inactivate enzymes involved in these systems or do so at a rate too slow to be of biological significance.

Antifibrinolytic Agents↗
PubMed2002

alpha(1)-Proteinase inhibitor mutants with specificity for plasma kallikrein and C1s but not C1.

Coagulation and complement proteinases are activated in sepsis, and one approach to therapy is to develop proteinase inhibitors that will specifically inhibit these proteinases without inhibiting activated protein C, a proteinase that is beneficial to survival. In this study, we made mutants of the serpin alpha(1)-PI, designed to mimic the specificity of C1-inhibitor. The P3-P2-P1 residues of alpha1-PI were changed from IPM to LGR and PFR, sequences preferred by C1s and kallikrein, respectively. Inhibition of C1s, kallikrein, factor XIIa, and activated protein C was assessed by SDS-PAGE, and by determination of the k(app) and SI. alpha(1)-PI-LGR inhibited C1s with a rate of 7790 M(-1)s(-1), but only minimal inhibition of C1 in a hemolytic assay was observed. Kallikrein, factor XIIa, and activated protein C were inhibited with rates of 382,180 M(-1)s(-1), 10,400 M(-1)s(-1), and 3500 M(-1)s(-1), respectively. alpha(1)-PI-PFR was a poor inhibitor of C1s, factor XIIa, and activated protein C, but had enhanced reactivity with kallikrein. Changing the P4' residue of alpha(1)-PI-LGR Pro to Glu reduced the activity with C1s, consistent with the idea that C1s requires hydrophobic residues in this region of the serpin for optimal interaction. The data provide insight into the requirements for kallikrein and C1s inhibition necessary for designing inhibitors with appropriate properties for further investigation as therapeutic agents.

Animals↗
PubMed1995

Complement analysis in adult patients with a history of bacteremic pneumococcal infections or recurrent pneumonia.

Complement deficiencies are known to be associated with increased susceptibility to bacterial infections. In the present study we investigated 80 patients with either a history of pneumococcal bacteremic infection, or recurrent pneumonia, or both. Hemolytic screening tests for complement deficiency were performed and serum concentrations of C1q, C1s, C2, C3, C4, C4 isotypes, factor B, factor D, and properdin were determined. Complete deficiencies of single complement proteins were not found. 10 patients (12%) had a C4 isotype deficiency, but the frequency of homozygous C4A and C4B deficiency was not significantly increased. Seven patients (9%) had hypocomplementemia with low concentrations of at least 2 complement proteins. One of these patients had profound depletion of classical pathway components and findings suggesting acquired C1 esterase inhibitor deficiency. 16 patients (20%) had minor complement aberrations. A majority of the patients with hypocomplementemia suffered from other conditions associated with pneumococcal infections. However, impaired complement function could be a significant predisposing factor in some patients with invasive pneumococcal infections or recurrent pneumonia.

Acute Disease↗
PubMed1996

A solid-phase antibody capture assay for the measurement of C1-inhibitor consumption in vivo.

C1-inhibitor (C1-Inh) is a serine esterase proteinase inhibitor (serpin) which plays an important role in regulating serine proteinases of the early inflammatory response. In this study, we describe a novel and versatile polyclonal antibody capture assay to examine C1-Inh consumption in vivo. This assay has advantages over previously described methods of measuring C1-Inh consumption as it allows the assessment of the relative amounts of native, complexed and cleaved inhibitor circulating in plasma. By using polyclonal antibodies specific for other complement proteins, the C1-Inh capture assay was adapted to measure in vivo activation of C3, C4 and factor B. C1-Inh consumption and complement activation were examined in the plasma of 21 normal individuals, 24 individuals with systemic lupus erythematosus (SLE), nine individuals with adult respiratory distress syndrome (ARDS) and in the paired plasma and synovial fluid from 18 patients with rheumatoid arthritis (RA). The C1-Inh capture assay revealed native, cleaved and complexed C1-Inh migrating at 115 kDa, 96 kDa and 209-225 kDa respectively, in normal plasma. C1-Inh consumption was increased in the plasma of all the inflammatory disorders examined, in comparison to normal plasma. It is proposed that this serpin capture assay could be adapted to the study of serpin involvement in a wide variety of inflammatory disorders.

Arthritis, Rheumatoid↗