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PubMedDate not supplied

Kinetic analysis of immune complex solubilization: complement function in relation to disease activity in SLE.

Solubilization of preformed bovine serum albumin (BSA) rabbit anti-BSA complexes in serum with kinetic analysis, haemolytic complement function, complement proteins C1q, C4, C3 and complexes containing C1 inhibitor (C1 INH-C1r-C1s-C1 INH) were serially investigated in relation to disease activity in 25 patients with systemic lupus erythematosus (SLE). Clinical assessment of disease activity was expressed using a validated global index (SLEDAI). Markedly decreased capacity to solubilize immune complexes in serum was mainly found in sever disease. By serial analysis, evidence of fairly persistently impaired classical pathway function was found in most of the patients. In partial contrast, impaired alternative pathway function was more clearly associated with active severe disease. Immune complex solubilization during short incubation (5-10 minutes) correlated with classical and alternative pathway-mediated haemolysis. Solubilization during long incubation (40 minutes) was correlated with haemolytic alternative pathway function. In some patients gradual impairment of solubilization during short incubation, and reduced classical pathway haemolytic activity were detectable 2-4 months before clinical manifestations prompted therapeutical intervention. SLEDAI was negatively correlated with solubilization during prolonged incubation (40 minutes) and with haemolytic alternative pathway function, further emphasizing involvement of the alternative pathway in severe disease. The findings emphasize the importance of impaired complement function due to complement activation in SLE. Assays for immune complex solubilization or other complement functions appear to be useful for monitoring disease activity in SLE.

Antigen-Antibody Complex↗
PubMed1995

Complement and IgG subclasses in agammaglobulinemic patients.

Complement and IgG subclass analysis was performed in six agammaglobulinemic patients suffering from recurrent bacterial infections. Complement analysis included functional activity of the classical (CH50) and the alternative pathway (APH50) of complement, the complement proteins C3, C4, factor B, the regulators C1-inhibitor, factors H and I as well as the C3-derived split product C3dg/C3d. Plasma concentrations of total IgG ranged between < 0.01 and 297 mg/dl. IgM and IgA were almost undetectable. Levels of all IgG subclasses, which in most cases were measurable only by sensitive ELISA, were markedly reduced in all patients. A pronounced activation of the complement system was observed in all patients as revealed by reduced titers of hemolytic function and elevated levels of C3dg/C3d. Despite the fact that complement activation by itself was the major reason for decreased C4 levels, from depressed plasma concentrations of the common allotypic variants C4A and C4B, a heterozygous C4 deficiency could not be excluded in 2/6 patients. Our data clearly show that, by application of sensitive analytical methods, agammaglobulinemic patients vary considerably in their ability to synthesize immunoglobulins. This may, at least in part, explain the heterogeneous pattern of clinical symptoms. The increased susceptibility of agammaglobulinemic patients to bacterial infections is reflected by a highly activated, and thereby depleted complement system.

Adolescent↗
PubMed1990

Decay-accelerating factor regulates complement-mediated damage in the human atherosclerotic wall.

Decay-accelerating factor (DAF) is an intrinsic membrane inhibitor that regulates the activity of C3 and C5 convertases of the classical and alternative complement pathways. Using two monoclonal antibodies, IC6 and IA10, DAF was localized by immunohistochemistry using streptavidin-biotin-peroxidase complex or silver-intensified immunogold techniques in aortic, iliac and femoral samples obtained at surgery and autopsy from 32 patients. DAF was localized on the cells and in the connective tissue matrix of the arterial wall. Fibrous plaques and intimal thickenings presented larger amounts than fatty streaks, intimae and normal areas. By Western blotting analysis, DAF extracted from the arterial wall had a molecular weight of about 67 kDa. Using a double-labeling technique, DAF and C5b-9 complexes were co-localized on nucleated cells and on cell debris. The cells isolated after enzyme digestion of the arterial wall were tested for the protective role of DAF to complement-mediated damage. When DAF of the sensitized cells was blocked by monoclonal antibodies, complement-mediated cell lysis was enhanced from 10-15% to 60-70%. The effect of anti-DAF antibodies was dose-dependent. DAF blocking in the absence of antibodies used for sensitization led to a lysis under 10%. These data suggest a protective role of DAF against autologous complement activation, however insufficient to prevent complement activation in the human atherosclerotic wall.

Adult↗
PubMed1996

Chronic inhibition of nitric oxide synthase in Heymann nephritis.

Effects of nitric oxide (NO) synthase inhibition on blood pressure and on the course of Heymann nephritis was examined in rats. L-NG-nitroarginine-methylester (L-NAME, 10 mg/100 ml in the drinking water for 12 weeks) was used as an inhibitor of NO synthase. Urinary excretion of guanosine 3',5'-cyclic monophosphate (cGMP), a second messenger of NO, was used as an indirect estimate of NO activity. Rats were divided into the following groups: control, nephritis, L-NAME, and nephritis-L-NAME. Urinary cGMP excretion was lower in the nephritis group (p < 0.05) and in the nephritis-L-NAME group (p < 0.005) compared with controls. Plasma atrial natriuretic peptide (ANP) levels were elevated in the nephritis (p < 0.001) and in the nephritis-L-NAME groups (p < 0.05. L-NAME treatment alone did not have any effect on plasma ANP levels. Blood pressure rose progressively in all L-NAME-treated rats. Most marked albuminuria developed in the nephritis-L-NAME group. No differences in the immunohistological findings were observed between the nephritis and the nephritis-L-NAME groups. NO synthase inhibition causes hypertension and aggravates albuminuria in chronic nephritis. Moreover, nephritis itself may decrease then production of cGMP either as a consequence of blunted NO activity or, in addition, because of ANP resistance. It appears that NO synthase inhibition does not change the immunological course of Heymann nephritis but rather the increased hemodynamic load makes the course of nephritis worse.

Albuminuria↗
PubMed1982

C1 inhibitor deficiency simulating systemic lupus erythematosus.

A 48-year-old Japanese woman with systemic lupus erythematosus-like lesions of the skin and lips was found to have hereditary angio-oedema. Complement studies revealed low CH50, C1q, C4 and C1 inhibitor levels, with normal C3 and C5 levels. Dramatic clinical improvement followed fresh normal human blood transfusion and systemic betamethasone administration, while the deficient complement component levels were unchanged.

Angioedema↗
PubMed1998

Complement and contact activation during cardiovascular operations in infants.

BACKGROUND: By comparing the results of cardiac operations with or without cardiopulmonary bypass (CPB) in infants in a prospective study, we sought to determine which part of the postoperative systemic inflammatory response was caused by CPB. METHODS: Thirty-five patients were divided into two groups: 11 infants operated on without CPB and 24 infants operated on with CPB. Blood samples were drawn before, during, and after the operation. We assessed complement function and the concentrations or activities of C1q, C3, C4, C1 inhibitor, factor B, the activated split product C3a, and prekallikrein and factor XIIa of the contact system. RESULTS: All of the patients exhibited a decrease of complement proteins. This was greater in infants who underwent CPB. A increase in C3a and factor XIIa and changes in prekallikrein activity occurred only in infants during CPB. CONCLUSIONS: Complement activation occurs in all infants, but is significantly higher in the group with CPB. Contact activation only occurs in patients who undergo CPB. Thus, the inflammatory response is caused by the use of a CPB circuit and to a lesser degree by surgical procedures and anesthesia.

Cardiac Surgical Procedures↗
PubMed1986

Influence of the human pancreatic secretory trypsin inhibitor on trypsin-induced C3 and kininogen cleavage: an in vitro study.

Cleavage of C3 and kininogen in human plasma following the addition of increasing amounts of human cationic trypsin was studied using an in vitro model. The cleavage was correlated to the degree of saturation of the plasma protease inhibitors alpha 2-macroglobulin and alpha 1-proteinase inhibitor, and also with varying amounts of human pancreatic secretory trypsin inhibitor. When alpha 2-macroglobulin reached about 70% saturation, there was a prompt cleavage of most of the C3 and kininogen in spite of the presence of 90% free alpha 1-proteinase inhibitor. The consumption of alpha 1-proteinase inhibitor decreased with increasing concentrations of the pancreatic secretory trypsin inhibitor. This inhibitor was needed in a concentration of about 10 mumol to block trypsin-induced C3 and kininogen cleavage completely. As trypsin is thought to be the key trigger enzyme of the pathophysiological changes in acute pancreatitis, it seems reasonable to propose that the pancreatic secretory trypsin inhibitor might be of therapeutic interest in severe acute pancreatitis provided large enough amounts can be made available.

Complement Activation↗
PubMed2006

Compstatin inhibits complement activation by binding to the beta-chain of complement factor 3.

Compstatin is a peptidic complement inhibitor that prevents the cleavage of complement factor 3 (C3) by C3 convertase. Compstatin differs from other C3-regulatory proteins, such as complement receptor (CR) 1 and decay-accelerating factor (DAF), in that it binds native as well as activated C3 fragments and acts through mechanisms that do not involve the destabilization of the C3 convertase or the accelerated degradation of C3b. Compstatin's activity most likely relies on its affinity for native C3 and the conformational change that results upon binding with C3. Although the intermolecular interactions between compstatin and C3 have been studied, the identity of the targeted region on C3 is still elusive. To address this issue, we synthesized a photo-crosslinking compstatin analog and used it to probe C3 for sites of interaction. We identified a 40-kDa region at the C-terminus of the beta-chain of C3 that included the binding site of the compstatin analog. The specificity of the binding was confirmed by inhibition studies, which showed reduced crosslinking signal after pre-incubation of C3 with compstatin but not with various inactive analogs. Binding studies performed with a recombinant homolog of the 40-kDa region confirmed these findings. Five smaller recombinant proteins corresponding to various overlapping regions of the 40-kDa fragment did not bind compstatin, suggesting that a proper protein conformation, only found in larger fragments, is required for compstatin binding. The identified region on the beta-chain has, thus far, not been implicated in C3 cleavage or interactions with other proteins. Therefore, further research on this part of the C3 molecule may have implications for studies on the regulation of C3 cleavage, as well as for complement-based drug design.

Binding Sites↗
PubMed2000

Temporal accrual of complement proteins in amyloid plaques in Down's syndrome with Alzheimer's disease.

The complement system constitutes a series of enzymatic steps involved in the inflammatory response and is activated in Alzheimer's disease (AD). Using Down's syndrome (DS) brains as a temporal model for the progression of AD, we examined components of the complement cascade and their relationship to other principal events in AD pathology: Abeta42 deposition, neuritic changes, neurofibrillary tangles (NFTs), and gliosis (reactive astrocytes, activated microglia). Adjacent sections of frontal cortex from 24 DS subjects ranging in age from 12 to 73 years were immunohistochemically examined for immunoreactivity (IR) of classical complement proteins (Clq and C3), markers indicating activation of complement (C4d and C5b-9), the complement inhibitor apolipoprotein J (apo J), and markers of AD neuropathology. Abeta42-labeled diffuse plaques were first detected in a 12-year-old DS subject and were not labeled by any of the complement antibodies. Colocalization of Abeta42 with Clq, C3, C4d, and/or apo J was first detected in compacted plaques in the brain of a 15-year-old DS patient with features of mature AD pathology, such as reactive astrocytes, activated microglia, dystrophic neurites, and a few NFTs. IR for C4d and C5b-9 (membrane attack complex, MAC) was observed in small numbers of plaque-associated dystrophic neurites and in focal regions of pyramidal neurons in this 15-year-old. The only other young (</=30 years) DS brain to show extensive complement IR was that of a 29-year-old DS subject who also displayed the full range of AD neuropathological features. All middle-aged and old DS brains showed IR for Clq and C3, primarily in compacted plaques. In these cases, C4d IR was found in a subset of Abeta42 plaques and, along with C5b-9 IR, was localized to dystrophic neurites in a subset of neuritic plaques, neurons, and some NFTs. Our data suggest that in AD and DS, the classical complement cascade is activated after compaction of Abeta42 deposits and, in some instances, can progress to the local neuronal expression of the MAC as a response to Abeta plaque maturation.

Adolescent↗
PubMed1999

Quality of reinfused drainage blood after total knee arthroplasty.

Reinfusion of postoperative wound drainage blood has become an attractive alternative in primary total knee and hip arthroplasty. Quality of the drainage blood was studied with respect to content of extracellular bioactive substances and coagulation split products. Using the HandyVac ATS autotransfusion system, drainage blood was collected and reinfused within 6 hours postoperatively from 10 patients undergoing primary total knee arthroplasty. Blood samples were collected from the patients immediately after and 1 hour after opening of the tourniquet and after reinfusion of drainage blood. Samples were also collected from the drainage blood immediately before and at the end of reinfusion. The leukocyte-derived and platelet-derived bioactive substances histamine, eosinophil cationic protein (ECP), eosinophil protein X (EPX), myeloperoxidase (MPO), plasminogen activator inhibitor type 1 (PAI-1), and activated complement factor C3(C3a) and various coagulation factors and split products were analyzed in patient and drainage blood samples. None of the patients received additional predonated autologous blood or allogeneic blood components during the study period. Within 6 hours postoperatively, 250 to 1,000 mL drainage blood was collected and reinfused. Histamine, ECP, EPX, MPO, PAI-1, and C3a content was significantly increased in drainage blood immediately before and at the end of reinfusion. Reinfusion did not change the concentration of these substances in samples from the patients. Coagulation factors and various split products showed that drainage blood was defibrinated. Reinfusion of drainage blood did not change the coagulative capacity of the patients. Drainage blood appears to be defibrinated and contains various extracellular leukocyte-derived and platelet-derived bioactive substances. Reinfusion does not change the coagulative capacity or the concentration of bioactive substances of patients.

Arthroplasty, Replacement, Knee↗
PubMed2003

Functional proteomics of the active cysteine protease content in Drosophila S2 cells.

The fruit fly genome is characterized by an evolutionary expansion of proteases and immunity-related genes. In order to characterize the proteases that are active in a phagocytic Drosophila model cell line (S2 cells), we have applied a functional proteomics approach that allows simultaneous detection and identification of multiple protease species. DCG-04, a biotinylated, mechanism-based probe that covalently targets mammalian cysteine proteases of the papain family was found to detect Drosophila polypeptides in an activity-dependent manner. Chemical tagging combined with tandem mass spectrometry permitted retrieval and identification of these polypeptides. Among them was thiol-ester motif-containing protein (TEP) 4 which is involved in insect innate immunity and shares structural and functional similarities with the mammalian complement system factor C3 and the pan-protease inhibitor alpha2-macroglobulin. We also found four cysteine proteases with homologies to lysosomal cathepsin (CTS) L, K, B, and F, which have been implicated in mammalian adaptive immunity. The Drosophila CTS equivalents were most active at a pH of 4.5. This suggests that Drosophila CTS are, similar to their mammalian counterparts, predominantly active in lysosomal compartments. In support of this concept, we found CTS activity in phagosomes of Drosophila S2 cells. These results underscore the utility of activity profiling to address the functional role of insect proteases in immunity.

Amino Acid Sequence↗
PubMed2005

Leishmania donovani promastigotes induce periphagosomal F-actin accumulation through retention of the GTPase Cdc42.

Leishmania donovani promastigotes inhibit phagosome maturation and induce the accumulation of periphagosomal F-actin during the establishment of infection within macrophages. These events are mediated by the surface glycolipid lipophosphoglycan (LPG), but the underlying mechanisms remain to be elucidated. In this study, we addressed the role of the Rho-family GTPases RhoA, Rac1 and Cdc42 in the uptake of L. donovani promastigotes and in the accumulation of periphagosomal F-actin. Confocal microscopy analyses revealed that association of both Rac1 and RhoA to phagosomes containing L. donovani promastigotes was independent of the presence of LPG. In contrast, Cdc42 and proteins required for F-actin assembly (Arp2/3, WASP, Myosin, alpha-actinin) were retained on phagosomes in a LPG-dependent manner. Expression of the RhoA inhibitor C3-transferase blocked the internalization of complement-opsonized promastigotes, whereas the dominant-negative Rac1N17 blocked the uptake of unopsonized promastigotes. The dominant-negative Cdc42N17 inhibited LPG-mediated phagosomal accumulation of F-actin and retention of Arp2/3 and Myosin. Thus, our data suggest that the effect of LPG on the accumulation of periphagosomal F-actin is the consequence of an abnormal retention or activation of Cdc42 at the phagosome.

Actins↗
PubMed2005

Effects of rottlerin on silica-exacerbated systemic autoimmune disease in New Zealand mixed mice.

Environmental crystalline silica exposure has been associated with formation of autoantibodies and development of systemic autoimmune disease, but the mechanisms leading to these events are unknown. Silica exposure in autoimmune-prone New Zealand mixed (NZM) mice results in a significant exacerbation of systemic autoimmunity as measured by increases in autoantibodies and glomerulonephritis. Previous studies have suggested that silica-induced apoptosis of alveolar macrophages (AM) contributes to the generation of the autoantibodies and disease. Rottlerin has been reported to inhibit apoptosis in many cell types, possibly through direct or indirect effects on PKCdelta. In this study, rottlerin reduced silica-induced apoptosis in bone marrow-derived macrophages as measured by DNA fragmentation. In NZM mice, RNA and protein levels of PKCdelta were significantly elevated in AM 14 wk after silica exposure. Therefore, rottlerin was used to reduce apoptosis of AM and evaluate the progress of silica-exacerbated systemic autoimmune disease. Fourteen weeks after silica exposure, NZM mice had increased levels of anti-histone autoantibodies, high proteinuria, and glomerulonephritis. However, silica-instilled mice that also received weekly instillations of rottlerin had significantly lower levels of proteinuria, anti-histone autoantibodies, complement C3, and IgG deposition within the kidney. Weekly instillations of rottlerin in silica-instilled NZM mice also inhibited the upregulation of PKCdelta in AM. Together, these data demonstrate that in vivo treatment with rottlerin significantly decreased the exacerbation of autoimmunity by silica exposure.

Acetophenones↗
PubMed1996

[Genetic aspects of endometriosis: features of the distribution of polymorphic gene frequencies].

In a group of patients with endometriosis and in a control group of healthy women, the polymorphism of the following systems were studied: ABO and RH blood-group systems; serum proteins haptoglobin (HP), transferrin (TF), vitamin D-transporting protein (GC), protease inhibitor (PI), and the third component of the complement (C3); serum enzymes-amylase of the loci 1 and 2 (AMY1 and AMY2), pseudocholinesterase (E2), and alkaline phosphatase (PP); erythrocytic enzymes-acid phosphatase (ACP1), phosphoglucomutase (PGM1), superoxide dismutase (SOD-A), esterase D (ESD), and glyoxalase (GLO1). Statistically significant differences between the groups compared were established for five genetic systems: ABO, E2, C3, TF, and PGM1. Among patient with endometriosis, the rare alleles of the locus ESD-ESD5 and ESD7-were found, along with ESD 5-5 homozygotes. Several genetic loci can be involved in the pathogenesis of endometriosis; their products can be specifically realized due to peculiarities of biochemical reactions in the organisms of people predisposed to this pathology.

ABO Blood-Group System↗
PubMed1977

[Serum concentrations of proteinase inhibitors, complement components and of acid alpha-1-glucoprotein in children with myocarditis (author's transl)].

We examined 4 panels of children and 40 control patients for their serum levels of the complement components C3, C4 and the C3 activator, the proteaseinhibitors alpha-1-antitrypsin, alpha-2-macroglobulin and acid alpha-1-glycoprotein. Children of the group with active myocarditis revealed the consumption of the complement system, increased protease inhibitors and elevated acid alpha-1-glycoprotein. Group 2, children with the clinical diagnosis chronic myocarditis or status post myocarditis showed in six of seven cases low complement levels and elevated alsGP. 4 children showed increased A1AT and five increased A2MG. In the third panel: status post myocarditis, we estimated in five of eight patients complement activation, 4 children showed increased A2MG and alsGP and in 3 cases elevated A1AT levels were detected. Group 4 children revealed no complement consumption and showed no increased levels for the other proteins estimated, with the only exception of 1 case with increased alsGP. The children of the control group showed normal levels for the six proteins. By means of the examinations an inflammatory process can be detected, tissue injury can be indicated and the participation of the immune system can be shown.

Adolescent↗
PubMed1998

[Genetic aspects of silicosis: polymorphic gene distribution frequency].

Electrophoresis and isoelectrofocusing were used to study polymorphism by 7 genetic loci: haptoglobin (Hp), proteinase inhibitor (PI), transferrin (TF), Vitamin D-transporting protein (GC), complement 3 (C3), phosphoglucomutase 1 (PGM1) and glyoxalase (GLO1) in 60 patients with silicosis and in 70 apparently healthy workers of the Dynamo plant. Comparison of the study groups by significant differences in the summary of the genetic information obtained suggests that 5 (Hp, C3, TF, PI, PGM1) of the 7 studied systems showed the hereditary features of silicosis. The gene carriers Hp*2, C3*F, PGM1*2-, PI*M1, TF*C1, TF*C16 TF*D, GC*R due to peculiar biochemical processes appear to have less adaptive potentialities and a greater likelihood of the disease on exposure to industrial factors.

Adult↗
PubMed2004

Effect of complement inhibition and heparin coating on artificial surface-induced leukocyte and platelet activation.

BACKGROUND: Exposure of blood to artificial surfaces, as in cardiopulmonary bypass, induces an inflammatory response involving complement, leukocyte and platelet activation. To elucidate the specific role of complement in this process, studies were performed on blood circulated in polyvinyl chloride tubing in the absence and presence of complement inhibitors. Parallel experiments were performed with heparin-coated polyvinyl chloride tubing, which is known to prevent complement and cell activation. METHODS: A novel experimental model was used, based on human whole blood anticoagulated with lepirudin. Complement activation products, myeloperoxidase, lactoferrin, and thrombospondin were quantified in enzyme immunoassays. Leukocyte CD11b expression and leukocyte-platelet conjugates were detected by flow cytometry. RESULTS: Increased levels of C3 activation products, alternative pathway convertase, and the terminal SC5b-9 complex, combined with unchanged levels of C1rs-C1-inhibitor complexes and marginal changes in C4 activation demonstrated that complement was activated through the alternative pathway. Granulocyte and monocyte CD11b expression and granulocyte-platelet conjugate formation were efficiently attenuated by blocking either factor D, C3, C5, or C5a receptor. In contrast, monocyte-platelet conjugate formation and release of myeloperoxidase, lactoferrin, and thrombospondin were not reduced by complement inhibition. Heparin-coated polyvinyl chloride tubing efficiently reduced all inflammatory markers studied, except for C1rs-C1-inhibitor complexes, which increased, consistent with the enhancing effect of heparin on C1-inhibitor function. This effect did not, however, reduce fluid-phase classic pathway activation induced by heat-aggregated immunoglobulin G. CONCLUSIONS: Leukocyte and platelet activation in response to artificial materials occur by mechanisms that vary in their dependence on complement. Heparin coating precludes both the complement-dependent and complement-independent reactions.

CD11 Antigens↗