Legumain in Acute Coronary Syndromes: A Substudy of the PLATO (Platelet Inhibition and Patient Outcomes) Trial

Background The cysteine protease legumain is increased in patients with atherosclerosis, but its causal role in atherogenesis and cardiovascular disease is still unclear. The aim of the study was to investigate the association of legumain with clinical outcome in a large cohort of patients with acute coronary syndrome. Methods and Results Serum levels of legumain were analyzed in 4883 patients with acute coronary syndrome from a substudy of the PLATO (Platelet Inhibition and Patient Outcomes) trial. Levels were analyzed at admission and after 1 month follow-up. Associations between legumain and a composite of cardiovascular death, spontaneous myocardial infarction or stroke, and its individual components were assessed by multivariable Cox regression analyses. At baseline, a 50% increase in legumain level was associated with a hazard ratio (HR) of 1.13 (95% CI, 1.04-1.21), P=0.0018, for the primary composite end point, adjusted for randomized treatment. The association remained significant after adjustment for important clinical and demographic variables (HR, 1.10; 95% CI, 1.02-1.19; P=0.013) but not in the fully adjusted model. Legumain levels at 1 month were not associated with the composite end point but were negatively associated with stroke (HR, 0.62; 95% CI, 0.44-0.88; P=0.0069), including in the fully adjusted model (HR, 0.57; 95% CI, 0.37-0.88; P=0.0114). Conclusions Baseline legumain was associated with the primary outcome in patients with acute coronary syndrome, but not in the fully adjusted model. The association between high levels of legumain at 1 month and decreased occurrence of stroke could be of interest from a mechanistic point of view, illustrating the potential dual role of legumain during atherogenesis and acute coronary syndrome. Registration URL: https://www.clini​caltr​ials.gov; Unique identifier: NCT00391872.

Bradykinin analysis revived--a validated method for determination of its stable metabolite in whole blood by LC-MS/MS

Investigation of bradykinin involvement in diseases like hereditary angioedema has been greatly hindered by its rapid metabolism and generation, induced by sampling. Because of this, reliable measurements of bradykinin have yet to be introduced in clinical practice. Prevention of bradykinin generation during sampling, and determination of the in vivo generated stable metabolite BK1-5, should allow a reliable indirect measure of bradykinin involvement. An LC-MS/MS method has been developed to determine BK1-5 in human whole blood. The method inactivates metabolizing enzymes with ethanol, followed by solid phase extraction (C18), separation (C8) and detection (linear ion trap) through the transitions 287.25→320.20 (y3, quantifier), 408.20 (b4, qualifier) for BK1-5, and 292.17→330.20 (y3, quantifier), 408.20 (b4, qualifier) for the heavy labelled internal standard. The method showed acceptable linearity (n=3, r(2)=0.994), intra-run precision (CV<15%), inter-run precision (CV<15%) and accuracy (CV<14%), without matrix effects. LLOQ was 265.5 pmol L(-1) and LOD was 35.4 pmol L(-1). The method was used on blood samples from patients with hereditary angioedema, where BK1-5 was measured during attacks and in remision. The samples showed elevated concentrations (up to 1.7 nmol L(-1) during attacks and 265.5 pmol L(-1) in remission) compared to healthy volunteers (<35.4 pmol L(-1)). This is the first time BK1-5 in hereditary angioedema patients has been measured.

Nuclear legumain activity in colorectal cancer

The cysteine protease legumain is involved in several biological and pathological processes, and the protease has been found over-expressed and associated with an invasive and metastatic phenotype in a number of solid tumors. Consequently, legumain has been proposed as a prognostic marker for certain cancers, and a potential therapeutic target. Nevertheless, details on how legumain advances malignant progression along with regulation of its proteolytic activity are unclear. In the present work, legumain expression was examined in colorectal cancer cell lines. Substantial differences in amounts of pro- and active legumain forms, along with distinct intracellular distribution patterns, were observed in HCT116 and SW620 cells and corresponding subcutaneous xenografts. Legumain is thought to be located and processed towards its active form primarily in the endo-lysosomes; however, the subcellular distribution remains largely unexplored. By analyzing subcellular fractions, a proteolytically active form of legumain was found in the nucleus of both cell lines, in addition to the canonical endo-lysosomal residency. In situ analyses of legumain expression and activity confirmed the endo-lysosomal and nuclear localizations in cultured cells and, importantly, also in sections from xenografts and biopsies from colorectal cancer patients. In the HCT116 and SW620 cell lines nuclear legumain was found to make up approximately 13% and 17% of the total legumain, respectively. In similarity with previous studies on nuclear variants of related cysteine proteases, legumain was shown to process histone H3.1. The discovery of nuclear localized legumain launches an entirely novel arena of legumain biology and functions in cancer.

Intra- and extracellular regulation of activity and processing of legumain by cystatin E/M

Legumain, an asparaginyl endopeptidase, is up-regulated in tumour and tumour-associated cells, and is linked to the processing of cathepsin B, L, and proMMP-2. Although legumain is mainly localized to the endosomal/lysosomal compartments, legumain has been reported to be localized extracellularly in the tumour microenvironment and associated with extracellular matrix and cell surfaces. The most potent endogenous inhibitor of legumain is cystatin E/M, which is a secreted protein synthesised with an export signal. Therefore, we investigated the cellular interplay between legumain and cystatin E/M. As a cell model, HEK293 cells were transfected with legumain cDNA, cystatin E/M cDNA, or both, and over-expressing monoclonal cell lines were selected (termed M38L, M4C, and M3CL, respectively). Secretion of prolegumain from M38L cells was inhibited by treatment with brefeldin A, whereas bafilomycin A1 enhanced the secretion. Cellular processing of prolegumain to the 46 and 36 kDa enzymatically active forms was reduced by treatment with either substance alone. M38L cells showed increased, but M4C cells decreased, cathepsin L processing suggesting a crucial involvement of legumain activity. Furthermore, we observed internalization of cystatin E/M and subsequently decreased intracellular legumain activity. Also, prolegumain was shown to internalize followed by increased intracellular legumain processing and activation. In addition, in M4C cells incomplete processing of the internalized prolegumain was observed, as well as nuclear localized cystatin E/M. Furthermore, auto-activation of secreted prolegumain was inhibited by cystatin E/M, which for the first time shows a regulatory role of cystatin E/M in controlling both intra- and extracellular legumain activity.

Marasmius oreades agglutinin (MOA) is a chimerolectin with proteolytic activity

The Marasmius oreades mushroom lectin (MOA) is well known for its exquisite binding specificity for blood group B antigens. In addition to its N-terminal carbohydrate-binding domain, MOA possesses a C-terminal domain with unknown function, which structurally resembles hydrolytic enzymes. Here we show that MOA indeed has catalytic activity. It is a calcium-dependent cysteine protease resembling papain-like cysteine proteases, with Cys215 being the catalytic nucleophile. The possible importance of MOA's proteolytic activity for mushroom defense against pathogens is discussed.

Cystatin E/M suppresses legumain activity and invasion of human melanoma

Background

High activity of cysteine proteases such as legumain and the cathepsins have been shown to facilitate growth and invasion of a variety of tumor types. In breast cancer, several recent studies have indicated that loss of the cysteine protease inhibitor cystatin E/M leads to increased growth and metastasis. Although cystatin E/M is normally expressed in the skin, its role in cysteine protease regulation and progression of malignant melanoma has not been studied.

Methods

A panel of various non-melanoma and melanoma cell lines was used. Cystatin E/M and C were analyzed in cell media by immunoblotting and ELISA. Legumain, cathepsin B and L were analyzed in cell lysates by immunoblotting and their enzymatic activities were analyzed by peptide substrates. Two melanoma cell lines lacking detectable secretion of cystatin E/M were transfected with a cystatin E/M expression plasmid (pCST6), and migration and invasiveness were studied by a Matrigel invasion assay.

Results

Cystatin E/M was undetectable in media from all established melanoma cell lines examined, whereas strong immunobands were detected in two of five primary melanoma lines and in two of six lines derived from patients with metastatic disease. Among the four melanoma lines secreting cystatin E/M, the glycosylated form (17 kD) was predominant compared to the non-glycosylated form (14 kD). Legumain, cathepsin B and L were expressed and active in most of the cell lines, although at low levels in the melanomas expressing cystatin E/M. In the melanoma lines where cystatin E/M was secreted, cystatin C was generally absent or expressed at a very low level. When melanoma cells lacking secretion of cystatin E/M were transfected with pCST6, their intracellular legumain activity was significantly inhibited. In contrast, cathepsin B activity was not affected. Furthermore, invasion was suppressed in cystatin E/M over-expressing melanoma cell lines as measured by the transwell Matrigel assay.

Conclusions

These results suggest that the level of cystatin E/M regulates legumain activity and hence the invasive potential of human melanoma cells.

Collagen I regulates matrix metalloproteinase-2 activation in osteosarcoma cells independent of S100A4

This work investigates the effect of cell-collagen I interactions on the synthesis and activation of MMP-2, as well as synthesis of MT1-MMP and TIMP-1, by using an in vitro model with 3D fibrillar and 2D monomeric collagen. In order to reveal whether the metastasis-associated protein S100A4 can influence the cell's response to the two forms of collagen, osteosarcoma cell lines with high and low endogenous levels of S100A4 were used. Attachment of osteosarcoma cells to 3D fibrillar and 2D monomeric collagen resulted in opposite effects on MMP-2 activation. Attachment to 3D fibrillar collagen decreased activation of proMMP-2, with a corresponding reduction in MT1-MMP. By contrast, attachment to monomeric collagen increased the amount of fully active MMP-2. This was caused by a reduction in TIMP-1 levels when cells were attached to monomeric 2D collagen. The effect of collagen on proMMP-2 activation was independent of endogenous S100A4 levels, whereas synthesis of TIMP-1 was dependent on S100A4. When cells were attached to monomeric collagen, cells with a high level of S100A4 showed a greater reduction in the synthesis of TIMP-1 than did those with a low level of S100A4. Taken together, this study shows that synthesis and activation of MMP-2 is affected by interactions between osteosarcoma cells and collagen I in both fibrillar and monomeric form.

Separation of Plasma Kallikrein and a Kallikrein-like Plasminogen Activator Generated by Acetone in Rat Plasma

Plasminogen activator (PGA), kininogenase (Kase) and benzoyl arginine ethyl ester (BAEe) activities generated in plasminogen-free rat plasma by incubation with acetone (23% v/v) at 22 degrees were purified. The activities passed unadsorbed through columns of DEAE-Sephadex A-50 (pH 7.8) and arginine methylester-Sepharose 4B (pH 8.5). Part of the activities (rat plasma kallikrein) was adsorbed onto a soybean trypsin inhibitor (SBTI)-Sepharose 4B column at pH 8.5. At pH 7.0 a fraction with higher ratios PGA/BAEe esterase and Kase/BAEe esterase was also adsorbed. Both fractions could be eluted with 5 mM sodium hydroxide. The fraction not adsorbed at pH 8.5, but adsorbed at pH 7.0 was designated low molecular weight plasminogen activator (LMr-PGA), a plasminogen activator fraction with higher molecular weight, but without esterase activity being also present (Berstad & Briseid 1982). LMr-PGA was strongly inhibited by tranexamic acid (AMCA) 0.10 mM, whereas the fraction designated rat plasma kallikrein was not. By polyacrylamide gel electrophoresis Mr-values in the range 120,000 to 130,000 were established for native samples of both rat plasma kallikrein and LMr-PGA, whereas Mr-values of 78,000 to 80,000 were established after treatment with SDS.

New biomarkers in an acute model of live Escherichia coli-induced sepsis in pigs

We developed a live Escherichia coli model of acute sepsis in pigs with emphasize on biomarkers reflecting the early inflammatory response of sepsis. Healthy pigs, 25-35 kg, were challenged intravenously (IV) (n = 12) or intrapulmonary (n = 6) with live E. coli and observed for 3 and 5 h respectively. Control pigs received culture medium (n = 6 + 3). Haemodynamic parameters and a broad panel of inflammatory mediators were measured. The dose of bacteria was carefully titrated to obtain a condition resembling the early phase of human septic shock. The IV group displayed a pro-inflammatory response [significant increase in tumour necrosis factor-alpha, interleukin (IL)-6 and IL-8] and an early anti-inflammatory response (significant increase in IL-10). For the first time, we demonstrate a significant increase in IL-12 and matrix metalloproteinase-9 (MMP) early in pig sepsis. Coagulation was activated (significant increase in thrombin-antithrombin complexes) and there was a significant decrease in the serum proteins suggesting capillary leakage. Haemodynamic parameters reflected a septic condition with significant decrease in systemic blood pressure, increases in heart rate, pulmonary artery pressure and base deficit. None of these changes was observed in the control group. Interleukin-1beta and vascular endothelial growth factor increased in both groups. Nitric oxide measurements suggested an initial pulmonary vascular endothelial inflammatory response. The intrapulmonary group, which did not resemble septic condition, showed a substantial increase in MMP-9. In this porcine model of sepsis, IL-12 and MMP-9 were detected for the first time. These biomarkers may have an impact in the understanding and future treatment of sepsis.

Characterization of cysteine proteases in Malian medicinal plants

Extracts form 10 different Malian medicinal plants with a traditional use against schistosomiasis were investigated for their possible content of proteolytic activity. The proteolytic activity was studied by measuring the hydrolysis of two synthetic peptide substrates Z-Ala-Ala-Asn-NHMec and Z-Phe-Arg-NHMec. Legumain- and papain-like activities were found in all tested crude extracts except those from Entada africana, with the papain-like activity being the strongest. Cissus quadrangularis, Securidaca longepedunculata and Stylosanthes erecta extracts showed high proteolytic activities towards both substrates. After gel filtration the proteolytic activity towards the substrate Z-Ala-Ala-Asn-NHMec in root extract of Securidaca longepedunculata appeared to have Mr of 30 and 97kDa, while the activity in extracts from Cissus quadrangularis was at 39kDa. Enzymatic activity cleaving the substrate Z-Phe-Arg-NHMec showed apparent Mr of 97 and 26kDa in extracts from roots and leaves of Securidaca longepedunculata, while in Cissus quadrangularis extracts the activity eluted at 39 and 20kDa, with the highest activity in the latter. All Z-Phe-Arg-NHMec activities were inhibited by E-64 but unaffected by PMSF. The legumain activity was unaffected by E-64 and PMSF. The SDS-PAGE analysis exhibited five distinct gelatinolytic bands for Cissus quadrangularis extracts (115, 59, 31, 22 and 20kDa), while two bands (59 and 30kDa) were detected in Securidaca longepedunculata extracts. The inhibition profile of the gelatinolytic bands and that of the hydrolysis of the synthetic substrates indicate the cysteine protease class of the proteolytic activities. Several cysteine protease activities with different molecular weights along with a strong variability of these activities between species as well as between plant parts from the same species were observed.

Evidence that unrestricted legumain activity is involved in disturbed epidermal cornification in cystatin M/E deficient mice

Homozygosity for Cst6 null alleles causes the phenotype of the ichq mouse, which is a model for human harlequin ichthyosis (OMIM 242500), a genetically heterogeneous group of keratinization disorders. Here we report evidence for the mechanism by which deficiency of the cysteine protease inhibitor cystatin M/E (the Cst6 gene product) leads to disturbed cornification, impaired barrier function and dehydration. Absence of cystatin M/E causes unrestricted activity of its target protease legumain in hair follicles and epidermis, which is the exact location where cystatin M/E is normally expressed. Analysis of stratum corneum proteins revealed a strong decrease of soluble loricrin monomers in skin extracts of ichq mice, although normal levels of loricrin were present in the stratum granulosum and stratum corneum of ichq mice, as shown by immunohistochemistry. This suggested a premature or enhanced crosslinking of loricrin monomers in ichq mice by transglutaminase 3 (TGase 3). In these mice, we indeed found strongly increased levels of TGase 3 that was processed into its activated 30 and 47 kDa subunits, compared to wild-type mice. This study shows that cystatin M/E and legumain form a functional dyad in epidermis in vivo. Disturbance of this protease-antiprotease balance causes increased enzyme activity of TGase 3 that could explain the observed abnormal cornification.

Expression of matrix metalloproteinases and the metastasis-associated gene S100A4 in human neuroblastoma and primitive neuroectodermal tumor cells

BACKGROUND

Matrix metalloproteinases (MMPs) and their endogenous inhibitors (tissue inhibitors of MMPs; TIMPs) have been shown to correlate with in vitro invasiveness and clinical outcome in several adult malignancies. The importance of MMP and TIMP expression in neuroblastoma (NB) and primitive neuroectodermal tumors (PNET) is incompletely understood. The aim of the current study was to relate in vitro invasion of NB and PNET cell lines with MMP and TIMP expression and evaluate the effect of a synthetic MMP inhibitor. Furthermore, S100A4 levels were determined because recent reports have suggested a possible association between MMPs, TIMPs, and the metastasis-associated gene S100A4.

METHODS

Expression of MMPs, TIMPs, and S100A4 was evaluated at both mRNA and protein levels in 2 human NB and 2 PNET cell lines. In vitro invasion and effects of the synthetic MMP inhibitor Marimastat were assessed in the Transwell chamber assay.

RESULTS

The most invasive cells expressed the highest levels of MMPs and S100A4. Marimastat reduced invasion by 30%.

CONCLUSIONS

In vitro invasion correlated with MMP and S100A4 expression. The fact that Marimastat reduced in vitro invasion is encouraging for further studies on a possible therapeutic application for proteinase inhibitors.

Colorimetric and fluorimetric microplate assays for legumain and a staining reaction for detection of the enzyme after electrophoresis

The cysteine endopeptidase legumain was recently discovered in mammalian cells, predominantly localized in the lysosomal system where it is believed to contribute to antigen processing for MHC class II. Here we describe rapid assay procedures for the enzyme in 96-well microplates with two substrates, a novel compound, succinyl-Ala-Ala-Asn-4-methoxy-2-naphthylamide, and benzyloxycarbonyl-Ala-Ala-Asn-4-methyl-7-coumarylamide. Both substrates are suitable for fluorimetric assays, but the naphthylamide also allows colorimetric detection of legumain activity, since the released 4-methoxy-2-naphthylamine gives a red product when coupled with the Fast Garnet color reagent. We show that the naphthylamide substrate can be used to visualize active legumain after electrophoresis in polyacrylamide gel. Both substrates provide assays that are reproducible and sufficiently sensitive to allow the assay of legumain in crude samples such as tissue homogenates, although the coumarylamide is the more sensitive. The specificity of both assay methods for legumain was verified by the lack of inhibition by E-64 and total inhibition by egg white cystatin.

C1-inhibitor attenuates hyperacute rejection and inhibits complement, leukocyte and platelet activation in an ex vivo pig-to-human perfusion model

Xenotransplantation may be a future alternative due to increased shortage of organs. Classical complement activation is central in hyperacute rejection in pig-to-human combinations. We investigated the effects of C1-inhibitor (C1-INH), a regulator of the complement and contact systems, on hyperacute rejection. Pig kidneys were perfused with fresh human blood to which either C1-INH (n = 6) or human serum albumin (n = 6) was added. The survival of the C1-INH perfused kidneys (mean 327 min) was significantly longer (p < 0.00001) than the controls (79 min). C1-INH substantially inhibited complement activation (C1rs-C1-INH complexes, C4bc, C3bc and terminal complement complex) (p < 0.001 for all) compared with the marked complement activation in the controls. No contact activation was found. Leukocytes and platelets were substantially activated (counts, myeloperoxidase, beta-thromboglobulin, thrombospondin, soluble P-selectin) in the control group, and this activation was markedly reduced by C1-INH (p < 0.02 for all). Immunohistochemistry showed less C1q, C3, TCC, IgG and fibrin deposition in the C1-INH group. C1-INH may be useful to attenuate hyperacute rejection, probably through inhibition of complement. The reduced activation of neutrophils and platelets may mainly be secondary to inhibition of complement.

Human hepatoma cells rich in P-glycoprotein display enhanced in vitro invasive properties compared to P-glycoprotein-poor hepatoma cells

Whether the phenotypes of drug resistance and metastatic activity in cancer are dependent on each other or not is controversial. We compared in vitro invasive properties of human hepatoma cells resistant to epirubicin and rich in P-glycoprotein (Pgp) (HB8065/R) with the parental epirubicin-sensitive, Pgp-poor cells (HB8065/S). The HB8065/R cells displayed elevated capacity to migrate in a transwell chamber assay (three- to fourfold compared to the HB8065/S cells), both in the absence and presence of a reconstituted basement membrane extract (Matrigel). In the presence of the P-gp inhibitor PSC 833 (1.5 micrograms/ml) the capacity of the HB8065/R cells to cross Matrigel-coated filters was attenuated by approximately 25%. Compared to the HB8065/S cells, the resistant cell line expressed higher level of plasminogen activator inhibitor (PAI)-1 mRNA (approximately threefold), which was reflected by a approximately fivefold increase in secreted PAI-1 immunoactivity (approximately 50 ng/10(6) HB8065/R cells). Furthermore, treatment with PSC 833 was associated with upregulation of PAI-1 mRNA (approximately 3.5-fold) and immunoactivity (approximately twofold) in the HB8065/R cells. Level of tissue inhibitor of metalloproteinases (TIMP)-1 was also significantly increased in the HB8065/R cells compared to the HB8065/S cells, whereas both cell lines showed low constitutive expression of TIMP-2. Levels of TIMPs were not altered by PSC 833. These data suggest that overexpression of Pgp in these hepatoma cells may covariate with the phenotypes of both enhanced in vitro invasiveness and high PAI-1 expression, whether randomly acquired or not.

Regulation of tissue-degrading factors and in vitro invasiveness in progression of breast cancer cells

Hormone-independent growth and invasiveness represent phenotypic properties acquired during early progression of breast cancer. We compared human mammary adenocarcinoma cells, MCF-7, which are estrogen-dependent and poorly metastatic, with the estrogen-independent and highly metastatic subline, MCF7/LCC1, with regard to expression of tissue-degrading factors of the matrix metalloproteinase (MMP)-and urokinase (uPA)-dependent degradative pathways, as well as for their in vitro invasive properties. Both cell lines showed low constitutive mRNA expression of the MMP inhibitor TIMP-1. Baseline expression of TIMP-2 mRNA was also very low in MCF-7 cells, whereas the MCF7/LCC1 level was much higher (approximately 10-fold). Furthermore, both cell lines revealed low constitutive capacity to migrate in an in vitro invasion assay. Treatment with 12-O-tetradecanoylphorbol-13-acetate (TPA; 100 nM) induced the mRNAs for TIMP-1 as well as for MMP-1, MMP-9, the uPA receptor, and the uPA inhibitor PAI-1, amongst which only the responses of MMP-9 and PAI-1 were cell-specific. The mRNA levels of MMP-9 and PAI-1 were approximately 10-fold and approximately 15-fold higher in MCF7/LCC1 cells compared to MCF-7 cells. The secretion of immunoreactive PAI-1 was considerably elevated (> 20-fold) in TPA-treated MCF7/LCC1 cells, whereas the TPA-dependent level of 92-kDa MMP-9 was only approximately 2-fold higher in MCF7/LCC1 cells than in MCF-7 cells. In both cell lines treatment with TPA was associated with an increase (approximately 10-fold) in in vitro migration, which in the MCF7/LCC1 cells was significantly attenuated by a reconstituted basement membrane extract (Matrigel). These data suggest that TPA-responsive in vitro invasive properties that are probably associated with PAI-1 expression may co-vary with progression from hormone-dependent to -independent breast cancer.

Polymorphonuclear elastase in human colorectal carcinoma

proteinases are required for invasion through the extracellular matrix (ECM) during tumor invasion and metastasis. Polymorphonuclear (PMN) elastase can degrade ECM components and modulate other proteinases. In the present study PMN elastase activity was found in tissue extracts from 8 of 15 human colorectal carcinomas. Immunoreactive PMN elastase was demonstrated in all carcinoma biopsies with particular enrichment at the tumor-host interface. Immunofluorescence staining localized immunoreactive PMN elastase mainly to neutrophile granulocytes. The human colon carcinoma cell lines Caco-2 and HT-29 did not express PMN elastase. An interaction between tumor cells and elastase producing leukocytes is suggested.

Cleavage of plasma high molecular weight kininogen in surgical ICU patients

OBJECTIVE

To characterize kininogens in plasma from surgical patients in the intensive care unit (ICU).

DESIGN

Prospective study.

SETTING

Surgical ICU.

PATIENTS

35 patients aged 19-79 years, divided into two groups: sepsis (defined by standard criteria) and nonsepsis.

MEASUREMENTS AND RESULTS

Studies of proteolytic degradation of H-kininogen showed degradation in both patient groups compared to healthy controls. Functional quantification of prekallikrein showed a reduction of prekallikrein in plasma from both patients groups. Functional quantification of kininogens by a cysteine proteinase inhibitor assay showed no significant differences between the patients and the controls. Immunological levels of H-kininogen and total kininogen were not significantly different from normal plasma. No differences could be detected between the two patient groups in any of the parameters studied.

CONCLUSIONS

This study showed that contact activation took place in surgical ICU patients: partial kinin release and consumption of prekallikrein took place in vivo.

Activation of the complement, coagulation, fibrinolytic and kallikrein-kinin systems during attacks of hereditary angioedema

Five patients with hereditary angioedema (HAE) were studied during attacks and remission as were healthy controls. The high levels of C1/C1-INH complexes, low C4 and high ratio C4 activation products (C4bc)/C4 also differed significantly during remission compared to controls. During attacks C4bc/C4 increased (922-2007; P = 0.022, remission versus attacks, median values throughout), C2 and CH50 dropped (111-31%; P = 0.043 and 110-36%; P = 0.016, respectively), TCC (C5b-9) increased (0.88-1.23 AU/ml; P = 0.028). Cleavage of HK increased to be almost complete during attacks (20-90%; P = 0.009). While factor XIa/serpin-complexes did not increase, a more than twofold rise in thrombin/antithrombin-complexes (0.20-0.50 microgram/l; P = 0.009) and in plasmin/alpha-2-antiplasmin-complexes (7.3-17 nmol/l; P = 0.028) was observed. For the first time cascade activation in HAE was studied simultaneously, and corroborates that attacks lead to activation of the kallikrein-kinin system, fibrinolysis and early part of the classical complement pathway. In addition, the authors present novel data of terminal complement and coagulation activation, the latter apparently not via FXIa.

Cysteine proteinase inhibitors reduce malignant melanoma cell invasion in vitro

Proteolytic enzymes are believed to be necessary for tumor cell invasion. We have studied the effects of the cysteine proteinase inhibitor E-64 and the serine and cysteine proteinase inhibitor leupeptin, on the ability of human malignant melanoma cells (LOX) to pass through an artificial basement membrane. Transwell chambers containing filters coated with the reconstituted basement membrane, Matrigel, were used. Nontoxic concentrations of the proteinase inhibitors reduced the invasion of LOX cells through Matrigel. E-64 (250 mumol/l) by 27% and leupepetin (250 micrograms/ml) by 46%. The proteinase inhibitors did not alter the growth rate of the tumor cells, their motility through uncoated filters, or their attachment to the Matrigel coated wells. Our results indicate that cysteine proteinases are involved in the degradation of basement membranes and thus contribute to the invasion of malignant melanoma cells.

Bradykinin release from high molecular weight kininogen in surgical ICU patients

The purpose of this prospective study was to characterize kininogens in plasma from surgical ICU patients. Thirty-five patients, ages 19-79 years, were divided into 2 groups: sepsis (defined by standard criteria) and nonsepsis. Studies of proteolytic degradation of H-kininogen showed degradation in both patient groups compared to healthy controls. Functional quantification of prekallikrein showed a reduction of prekallikrein in plasma from both patient groups. Functional quantification of kininogens by a CPI (cysteine proteinase inhibitor) assay showed no significant differences between the patients and the controls. Immunological levels of H-kininogen and total kininogen were not significantly different from normal plasma. No differences could be detected between the two patient groups in any of the parameters studied. In conclusion, this study supported contact activation taking place in surgical ICU patients, a partial kinin release and a consumption of prekallikrein has taken place in vivo.

Quantification of kininogens in plasma. A functional method based on the cysteine proteinase inhibitor activity

We have previously reported on a microassay based on human kininogens as cysteine proteinase inhibitors (CPIs), which could quantify partially purified kininogens from different biological fluids (J Pharmacol Meth 26, 113-124, 1991). In the present study we describe a functional method that, when assuming a 1:1 stoichiometry between papain and kininogen, allows a direct measurement of the molar concentration of kininogens in plasma. The principle of the method is that the target enzyme papain is inhibited by kininogens present in added diluted plasma. The residual activity of papain, not inhibited in this reaction, subsequently hydrolyzes the added peptide substrate (S-2302), generating a yellow colour which is read in a microplate reader at 405 nm. Relating the test samples to a standard curve established from known concentrations of E-64 (a selective low molecular weight inhibitor of cysteine proteinases), we could quantify kininogens on a molar basis. A major problem when first applying this method to plasma, was the interference of alpha 2-macroglobulin, which inhibited papain and generated a complex able to split the chromogenic substrate. The interference of alpha 2-macroglobulin was eliminated by an initial acid treatment of plasma followed by dilution with a buffer containing methylamine. The specificity for kininogens in this assay is demonstrated by the following observations: Commercial pooled normal plasma contained 3.2 microM CPI activity, in good agreement with the expected molar concentration of kininogens. After gel filtration of a plasma sample with a CPI activity of 3.4 microM, two peaks with CPI activity were identified as H-kininogen (0.9 microM) and L-kininogen (2.5 microM), both in good accordance with expected concentrations of the two kininogens. Plasma deficient of kininogens had a minimal inhibitory capacity towards papain.

Hereditary angio-oedema: new clinical observations and autoimmune screening, complement and kallikrein-kinin analyses

OBJECTIVES

To study clinical and laboratory manifestations of hereditary angio-oedema (HAE).

SUBJECTS

Thirty-three affected members of a kindred of 63.

RESULTS

Oedematous attacks in the skin, mucous membranes and gastrointestinal tract with fluid displacement were elicited by mental and physical stress, minor traumas, dental and surgical procedures, eruption of teeth, tonsillitis, pregnancies, and use of oestrogen-containing pills including menopausal substitution. Every adult woman with symptomatic HAE (n = 11) showed symptoms of urinary tract infections in conjunction with the attacks (P = 0.010), and also experienced more spontaneous abortions or premature labours (P = 0.037) than healthy relatives. Patients with HAE of both sexes more frequently reported heartburn or peptic ulcers (P = 0.002). Rheumatic complaints were reported by 53% of HAE patients and 12% of their unaffected relatives (P = 0.013), but biochemical screening for 18 autoantibodies and quantitation of immunoglobulins did not reveal statistically significant differences between the two groups. C3, prekallikrein, total kininogen, high molecular weight kininogen (HK), alpha-2-macroglobulin and factor XII were not significantly different in HAE patients. In contrast, levels of C1-INH and C4 were depressed and cleaved HK increased in patients compared to unaffected relatives.

CONCLUSIONS

HAE manifests in a variety of ways, and may influence risk of spontaneous abortions and premature labour.

C3 is activated in hereditary angioedema, and C1/C1-inhibitor complexes rise during physical stress in untreated patients

Seven patients with hereditary angioedema (HAE) were studied to understand further how physical exercise may induce attacks. The most pronounced differences between patients and controls, however, were independent of the controlled bicycle run (mean values in patients/ controls); C4(g/L): 0.12/0.28 (P = 0.0122); C4bc (AU/ml): 137.0/18.0 (P = 0.0002); C4d (mg/mL): 5.03/2.35 (P = 0.0004); C3bc (AU/ml): 8.4/6.3 (P = 0.0049); C3a (AU/ml): 11.1/5.6 (P = 0.0102). The ratio C4bc to C4 was 1141 versus 64. Consequently, a substantial part of the low amount of C4 left in HAE patients consists of activation products, and the authors show for the first time that a mild but significant activation of C3 occurs in HAE. The two HAE patients treated with danazol had values of C1-INH function and antigen, C4, and C2 in-between those of normal and untreated patients, and lower levels of split products from C4 and high molecular weight kininogen than untreated patients. As a result of the exercise, fibrinolysis increased significantly in both patients and controls, while C1/C1-INH complexes rose significantly only in the five HAE patients without treatment when compared to the seven controls (P = 0.0089). This study thus suggests that complement activation is enhanced in untreated HAE patients following physical stress.

The fibrinolytic system in human ascites

BACKGROUND

We recently reported that the contact and kallikrein-kinin systems are activated in malignancy-related ascites. We have now studied the fibrinolytic system in ascites and plasma from patients with gastrointestinal cancer(n = 14) and non-malignant liver disease (n = 18).

METHODS AND RESULTS

Enzyme immunoassays (EIAs) showed that urokinase and tissue plasminogen activators (uPA, tPA) and PA inhibitors (PAI-1, PAI-2) were present in ascites from both patient groups and that tPA was the predominant PA. uPA, tPA, and PAI-1, were detected in plasma from patients and controls. These EIA findings were supported by zymography studies. Functional assays showed considerable generation of plasmin-like activity and low plasminogen and antiplasmin values in malignancy-related ascites. The plasmin/antiplasmin and tPA/PAI-1 ratios were particularly high in malignancy-related ascites as compared with non-malignant ascites. Plasma from the liver disease patients showed a higher tPA/PAI-1 ratio and, thus a higher potential for plasminogen activation than plasma from cancer patients and controls. Patient plasma showed low values of plasmin-like activity, antiplasmin, and plasminogen.

CONCLUSION

Our findings show that the fibrinolytic system is activated in malignancy-related ascites.

Antigen levels of urokinase plasminogen activator and its receptor at the tumor-host interface of colorectal adenocarcinomas are related to tumor aggressiveness

The distributions of urokinase and tissue plasminogen activators (uPA, tPA), uPA receptor (uPAR), and plasminogen activator inhibitors (PAI-1, PAI-2) were studied immunohistochemically in two subsets of colorectal adenocarcinomas with low and high aggressiveness, respectively: nine Dukes' stage A tumors with additional other good prognostic markers and 13 Duke's stage C tumors with also other poor prognostic markers (referred to as Dukes' stage A and Dukes' stage C tumors). The results showed that these components of the tissue destructive plasminogen activation system were accumulated at the invading front of the tumors. Both tumor groups showed accumulations of uPA, uPAR, and PAI-1 at the tumor-host interface compared with the location within the tumor epithelium and the adjacent normal mucosa and muscularis propria (all P < .05). However, the uPA level at the tumor-host interface in the Dukes' stage C tumors was twice the level in the Dukes' stage A tumors (P < .05). The uPAR level was also significantly higher in the Dukes' stage C tumors (P < .05), whereas the PAI-1 level was not significantly higher. This may indicate that uPA in more aggressive tumors exceeds the inhibitory capacity represented by PAIs, resulting in enhanced tissue destructive potential that promotes tumor invasion. uPA and uPAR antigen levels and the uPA/PAI-1 ratio at the tumor-host interface appeared to be related to tumor aggressiveness in colorectal cancer.

Activation of the plasma contact system and hemodynamic changes after graft revascularization in liver transplantation

In this study, the relation between activation of the plasma contact system and hemodynamic changes during orthotopic liver transplantation was evaluated. Nineteen consecutive courses of OLT in 17 adult patients were investigated. Veno-venous bypass was used in all patients. Blood samples were drawn through all phases of the procedure, and analyzed for the following parameters using functional techniques (chromogenic peptide substrate assays): plasma kallikrein (KK), prekallikrein, functional plasma kallikrein inhibition, C1 inhibitor, and alpha 2-macroglobulin. Plasma high molecular weight kininogen (HK) degradation was evaluated using the immunoblotting technique. An abrupt rise in KK activities occurred within 1 min after portal reperfusion of the liver graft (7-16 U/L, P < 0.05). Simultaneously, proteolytic breakdown of HK was seen. The elevated KK activities were maintained the next 1 1/2 hr. Ten min after graft reperfusion, a significant increase in cardiac output compared with the anhepatic phase (7.2-12.4 L/min, P < 0.05) was found. At the same time, systemic vascular resistance fell significantly (817-408 dynes x sec/cm-5, P < 0.05). The increase in plasma KK activities accompanied by simultaneous degradation of HK seen immediately after reperfusion of the liver graft may be due to contact activation as recipient blood contacts with the underlying basement membrane of injured sinusoidal endothelium in the transplanted liver. We suggest that hemodynamic changes associated with the postreperfusion syndrome seen after revascularization of the liver in OLT could at least be caused in part by bradykinin release due to contact activation.

Dextran sulphate activation of the contact system in plasma and ascites

We have previously reported on the presence of proenzymes and inhibitors of the contact system in ascitic fluid. Malignancy-related ascites was also found to contain both high and low molecular weight kininogen (HK and LK). On this basis we have studied a possible activation of the contact system in ascites. Generation of amidolytic activity towards the chromogenic substrate S-2302 after incubation with dextran sulphate (DXS), was found in ascites from patients with gastrointestinal cancer, but not in ascites from patients with benign liver disease. It is concluded that malignancy-related ascites allows contact activation to take place, while benign ascites does not. This activation process, generating bradykinin, could possibly be of relevance to the mechanism of ascites generation. Plasma samples from patients with ascites were also tested in relation to activation of the contact system. Activation was evaluated by immunoblotting, studying the disappearance of intact HK after the initiation of activation with different concentrations of DXS. In control plasma, activation took place at low concentrations of DXS (25 - 50 micrograms/ml). In plasma samples from patients with malignancy-related or benign ascites, contact activation was depressed. In some samples concentrations of DXS up to 1 mg/ml, were not able to activate the contact system at all. Concentrations of proenzymes and relevant inhibitors in the contact system, HK and total protein were also determined. We found the concentration of prekallikrein to be positively correlated with the degree of activation. Concentrations of inhibitors such as C1-inhibitor, did not show any correlation with activation.

Expression and release of plasminogen activators, their inhibitors and receptor by human tumor cell lines

Plasminogen activators (PAs) and their inhibitors (PAIs) can be produced by tumor cells and surrounding inflammatory cells and fibroblasts. The present study evaluate both the expression and release of PAs (uPA and tPA) and PAIs (PAI-1 and PAI-2) from cultured cells, and also the expression of uPA receptor (uPAR). Immunocytochemistry showed that PAs, PAIs and uPAR were present to different extents on the surface of colon carcinoma cells (Caco-2, HT-29), malignant melanoma cells (LOX) and normal fibroblasts. uPA immunoreactivity was intermediate in Caco-2, HT-29 and LOX and weak in the fibroblasts. tPA immunoreactivity was intermediate in Caco-2 and LOX and weak in HT-29 and fibroblasts. PAI-1 and PAI-2 immunoreactivities were absent in HT-29, weak in Caco-2 and strong in fibroblasts. In LOX the immunoreactivity was intermediate for PAI-1 and strong for PAI-2. uPAR immunoreactivity was weak in Caco-2, HT-29 and LOX and negative in fibroblasts. ELISAs on conditioned medium detected that the colon carcinoma cells Caco-2 and HT-29 did not release any PAs or PAIs. LOX released tPA (median 9 ng/million cells at 72 hours), PAI-1 (1050 ng/million cells) and PAI-2 (245 ng/million cells), and fibroblasts released uPA (1 ng/million cells) and PAI-1 (910 ng/million cells). These results show that both tumor cells and fibroblasts express tissue destructive enzymes, PAs and PAIs, whereas only the tumor cells express the uPAR required for focalization and regulation of PA activity at the cell surface. The melanoma cells LOX and fibroblasts also released PAs and PAIs, in contrast to the colon carcinoma cells Caco-2 and HT-29.

Effect of time, temperature and additives on a functional assay of C1 inhibitor

There are different recommendations for the handling of blood samples for analyses of the kallikrein-kinin or complement system, respectively. C1 inhibitor (C1-INH) takes a crucial part in both systems. In order to establish recommendations for blood specimen collection and transport for making the diagnosis of hereditary angioedema (HAE), the effect of time, temperature and different additives on C1-INH function and antigen was determined. We used blood samples from normals and patients suffering from HAE type I. Plasma containing EDTA, heparin, sodium citrate or polybrene-EDTA, and serum were assayed after incubations at 4 degrees C or 37 degrees C for 6 or 24 h. In addition, pooled serum was incubated for up to 5 days at room temperature. A modest decrease in C1-INH function was observed as an effect of storage-time in samples from normals (p = 0.039) and a substantial decrease was seen for the HAE patients (p = 0.0002). No significant effect of temperature (4 degrees C or 37 degrees C) was found. Clotting did not reduce C1-INH activity. Plasma containing heparin or polybrene interfered with the functional assay, yielding falsely high and low values, respectively. C1-INH functional assay performed within 24 h in serum, EDTA-treated or citrated plasma discriminated well between HAE patients and normals. This was also the case for serum kept at room temperature for up to 5 days, although a modest fall in C1-INH function was seen in the incubation period. For practical purposes we recommend serum as the sample of choice, preferably received within 48 h.

[Angioedema associated with ACE inhibitors]

Angio-oedema as an adverse effect of angiotensin converting enzyme-inhibitors (ACE-inhibitors) is reported to occur in one to two of 1,000 treated patients per year. This estimate may be too low, since the swelling of face, lips, tongue and throat is very often attributed to food allergy. Furthermore, attacks of oedema may occur after months or even years of ACE-inhibitor treatment, thereby obscuring the link to the medication. This adverse effect is non-immunogenic. The oedema is explained by local enhancement of bradykinin, which under normal circumstances is broken down by angiotensin converting enzyme. The question of what makes some people vulnerable is still unsolved. The oedema can develop quickly and may lead to suffocation. In many cases, conventional antiallergic treatment in the form of steroids, antihistamines and epinephrine has inadequate effect. Intubation of the larynx may be necessary, but can be extremely difficult in the case of massive glassy oedema. Involvement of the neck can sometimes hinder tracheotomy, making early intervention essential. The authors describe two patients with moderate swellings, and discuss a potential, yet experimental, use of C1-inhibitor concentrate in the treatment of ACE-inhibitor provoked angioedema.

C1 inhibitor and diagnosis of hereditary angioedema in newborns

Symptoms of hereditary angioedema may present during the child's first years. Attacks may be a particular threat to the narrower airway of the child. An early diagnosis is most valuable because effective C1 inhibitor (C1 INH) concentrate is available. We present a reference area for the antigenic and functional determination of C1 INH by using uncontaminated umbilical cord blood from 80 normal newborns collected by puncturing vessels in the newly delivered placenta. We examined two full-term babies (1 and 2) from mothers with hereditary angioedema type I the same way. The concentration of C1 INH antigen was determined by radial immunodiffusion. The C1 INH functional assay was based on the addition of a known quantity of C1s, which enzymatically splits a chromogenic substrate. The test was performed in the presence of methylamine and heparin in a kinetic microtiter plate assay. Citrated plasma was used in both assays. The data obtained in the 80 cord blood samples (2.5-97.5 percentile) were 0.11-0.22 g/L for C1 INH antigen (adults, 0.15-0.33 g/L) and 47.2-85.9% for C1 INH function (percentage of adults). In cord blood, baby 1 had an antigenic value of 0.12 g/L (7.5 percentile) and C1 INH function of 61.8% (42 percentile). The corresponding values for baby 2 in cord blood were less than 0.05 g/L (0.106 g/L < 2.5 percentile) and 34.3% (12.9% < 2.5 percentile). Baby 2 had markedly lower C4 values yet much higher C4 activation products than baby 1. At 4 mo, baby 1 had an antigenic C1 INH value of 0.24 g/L.(ABSTRACT TRUNCATED AT 250 WORDS)

Differential diagnosis of human ascites: inhibitors of the contact system and total proteins

To assess their accuracies as markers for malignancy, we assayed alpha 2-macroglobulin, C1-inhibitor, alpha 1-protease inhibitor, and total proteins in ascites and plasma from patients with gastrointestinal cancer (n = 15) and non-malignant liver disease (n = 13), using functional and immunologic assays. For all inhibitors and total proteins determined in ascites, the values in the cancer group were significantly higher than the corresponding values in the group with non-malignant liver disease. The diagnostic accuracy for differentiating malignancy-related from non-malignant ascites was 93% for a alpha 1-protease inhibitor value > or = 50% of the pool plasma value and 90% for alpha 2-macroglobulin > or = 16%, C1-inhibitor > or = 40% (all functional assays), and total proteins > or = 20 g/l (biuret). In conclusion, functional assays for alpha 2-macroglobulin, C1-inhibitor, and alpha 1-protease inhibitor and determination of total proteins in ascites appeared to be very informative tests for the differential diagnosis of ascites. The test for alpha 1-protease inhibitor gave higher specificity (92% versus 77%) and likelihood ratio for a positive test (12 versus 4) compared with the other tests.

The contact system in human malignant and benign ascites

The plasma contact system was studied in ascites and plasma from patients with gastrointestinal cancer and patients with liver failure. Our study demonstrates the presence of factor XII, factor XI, and prekallikrein and their main inhibitors in ascites and plasma from both patient groups. Both factor XII-like and plasma kallikrein-like activities were detected in the malignant ascites. The kallikrein-like activity in malignant ascites was found in complex with alpha 2-macroglobulin. In plasma samples from the patients functional values of factor XII and prekallikrein were decreased compared to controls. In benign ascites the proenzyme levels were significantly lower than in malignant ascites. Functional inhibition values in ascites and plasma from patients were unexpectedly high. Our findings indicate that the plasma contact system is activated in the ascites from cancer patients. Activation of the contact system generates vasoactive mediators, which may play a role in the accumulation of malignant ascites.

Location of plasminogen activator (PA) and PA inhibitor in human colorectal adenocarcinomas

Both the coagulation and fibrinolytic cascades generate proteolytic enzymes which appear to be essential for tumor invasion. In the present investigation adenocarcinomas and normal colon from 14 patients with colorectal cancer were studied by immunohistochemistry. The most striking observation was an enrichment of plasminogen activator inhibitor in the tumor tissue, whereas no such immunoreactivity was detected in the biopsies of normal colon. The tumor-host interface was characterized by a massive accumulation of inflammatory cells, macrophages and T lymphocytes. In this area fibrin(ogen) immunoreactivity as a sign of local activation of the coagulation cascade was also seen. The transition zone between the tumor and normal tissue was furthermore characterized by a marked enrichment of urokinase plasminogen activator immunoreactivity. The study strongly indicates that proteases and inhibitors of the fibrinolytic system may be of great importance in tumor invasion.

Activation of the plasma kallikrein-kinin system in respiratory distress syndrome

Components of the plasma kallikrein-kinin and fibrinolytic systems together with antithrombin III were measured the first days postpartum in 13 premature babies with severe respiratory distress syndrome (RDS). Seven of the patients received a single dose of porcine surfactant (Curosurf) as rescue treatment. Nine premature babies without lung disease or any other complicating disease served as controls. There were no differences in prekallikrein values between surfactant treated and non-treated RDS babies during the first 4 d postpartum. The controls had, however, significantly higher prekallikrein values than the RDS babies already at the first day of age (mean +/- SD 32 +/- 8% in controls versus 22 +/- 6 and 21.5 +/- 5% in the treated and nontreated RDS groups, respectively). Plasma kallikrein activities did not differ between RDS and control patients. Plasma kallikrein inhibition values, which increased steadily in all groups, were lower in the RDS babies treated with surfactant than in controls at d 2 and 4. The degree of degradation of plasma high molecular weight kininogen was measured in RDS patients treated with surfactant and was significantly higher when compared with controls at d 1, demonstrating an increased proteolysis of kininogen to kinin early in RDS. There were no differences in plasminogen and plasmin values between RDS and control babies. This study shows that the plasma kallikrein-kinin system is activated in RDS. This system as well as the fibrinolytic system does not seem to be influenced by rescue instillation of a single dose of porcine surfactant into the lungs of premature babies with RDS.

Hemodynamic and proteolytic effects of intravenous injection of purified human plasma kallikrein

To investigate the precise hemodynamic effects of purified human plasma kallikrein, small doses (0.3 U/kg) of this proteolytic enzyme were infused over 10 s in five pigs. Hemodynamic performance was evaluated by means of a Swan-Ganz catheter, and parameters of the plasma kallikrein-kinin, coagulation, and fibrinolytic systems were determined by means of chromogenic peptide substrate assays. The infusions of plasma kallikrein were followed by rapid decreases in mean arterial pressure (to 43 +/- 2% of baseline values) and increases in cardiac output (to 145 +/- 6% of baseline values), accounting for marked decreases in systemic vascular resistance, to 28 +/- 1% of initial values. Heart rate, mean pulmonary arterial, central venous, and pulmonary capillary wedge pressures did not change after the injection. Pulmonary vascular resistance decreased to 69 +/- 3% of baseline values. The hemodynamic changes gradually normalized during the following 10 min. Functional levels of prekallikrein, kallikrein, kallikrein inhibition, prothrombin, antithrombin III, plasmin, and antiplasmin were not affected by the injection or the resulting hemodynamic changes; the hematocrit and the number of circulating leukocytes or platelets were also unaffected.

Characterization of kininogens in human malignant ascites

Ascites from seven patients with advanced cancer were studied to characterize the kininogens. Immunological quantification of low molecular weight kininogen (L-kininogen) and high molecular weight kininogen (H-kininogen) by rocket immunoelectrophoresis showed values of 42% and 39%, respectively, compared to control plasma. Release of kinin from the ascites samples was assayed on an isolated rat uterus. The total kinin released from the kininogens was 39% of the value in control plasma, while release selectively from H-kininogen amounted to 25% of plasma. This indicates about 30% of the bradykinin in H-kininogen to be released in vivo in ascites, and points to kinins as possible mediators of the increased vascular permeability causing accumulation of ascites. The function of kininogens as cysteine protease inhibitors (CPIs) was assayed as well, indicating that both L- and H-kininogen function as cysteine protease inhibitors in human ascitic fluid. The proteolytic cleavage of H-kininogen in ascites was studied by polyacrylamide gel electrophoresis and subsequent immunoblotting. H-kininogen was extensively cleaved in ascites compared to control plasma, with large amounts present of a degraded form with Mr of 99 kDa. The bands observed compared well with those described in plasma, and are consistent with contact activation taking place in ascites.

Evaluation of a microassay for human kininogens as cysteine protease inhibitors

Several methods have been described for the identification and quantification of kininogens based on both immunochemical and functional characteristics. This article presents a rapid, cheap and simple microplate assay of kininogens based on their ability to inhibit cysteine proteases. The target enzyme papain is activated by cysteine HCl and the activated enzyme will be inhibited by added kininogens. The residual enzyme activity that is not inhibited in this reaction subsequently hydrolyzes the added substrate, S-2302, generating a yellow color that is read in a microplate reader at 405 nm. This method is very sensitive, the smallest amount of kininogen that causes significant inhibition of papain is established to be 0.01 micrograms. As a quantitative method, the assay performs accurately when approximately 0.1 micrograms of low molecular weight kininogen or high molecular weight kininogen is added to the test system. The within-run coefficient of variation (%) of the method was 1.7% when the inhibition of papain was in the range 45-70% and the day to day variation as low as 2.3% when performed with a papain inhibition of 80%. Applications of the method are presented, studying chromatographic separated kininogens in plasma, ascites, and urine.

A new case of total kininogen deficiency

Six families with total kininogen deficiency have been described in the literature. We report herein an additional case in a Pakistanese woman. The defect was discovered accidentally due to lack of normal clot formation in a preoperative routine blood sample. She had a borderline prolonged bleeding time, and reported occasional hematuria, but was otherwise without symptoms. Absence of both kininogen species was proven by functional and immunological methods, and by lack of kinin formation both by plasma kallikrein and hog pancreas kallikrein. Prekallikrein was reduced, probably because the main part circulates complexed to high molecular kininogen. Activation of intrinsic fibrinolysis was grossly hampered, and cold activation of coagulation absent with epsilonaminocaproic acid and greatly retarded by dextran sulfate, kaolin and ellagic acid. Together with other evidence the findings indicate the following order of importance for contact activation in plasma--F.XII, high molecular weight kininogen, prekallikrein.

[The role of proteases in the growth, invasion and spread of cancer cells]

Cancer cells show a greater capability than normal cells do to break down proteins in the surrounding tissue. This tissue destruction involving proteolytic enzymes is probably essential for the invasion and metastatic spread of malignant cells. The process takes place through an interplay of proteolytic enzyme systems where plasmin-mediated proteolysis plays an important role. Plasminogen activator activity and receptors for plasminogen activators have been discovered in tumors, mainly in areas with invasive growth and tissue degradation. Patients with malignant diseases often demonstrate abnormalities in their blood coagulation, including hyperaggregability of platelets. Experimental research has shown that therapy with antiplatelet drugs, and prophylaxis with protease inhibitors, can limit spread of tumors.

Rocket immunoassay of high and low molecular weight kininogens in human plasma

High molecular weight kininogen (HMWK) and low molecular weight kininogen (LMWK) in human plasma could be rapidly (36 min.) separated on a DEAE-Sepharose Fast Flow column (1.0 x 5 cm and 0.50 ml plasma) by applying a NaCl step gradient. Quantification was then carried out by the Laurell rocket method with an antiserum raised against HMWK. Standard preparations for the assays were (I) crude HMWK and (II) crude LMWK prepared by the one-step procedure mentioned. In disc PAGE (8% with 0.1% SDS) immunoblot showed two main bands in I, migrating to apparent mol.wts. of 180,000 and 120,000. The 180,000 band predominated in native plasma. Purified HMWK (spec.act. 14 micrograms bradykinin/A 280) yielded in addition a band corresponding to a mol.wt. of 100,000. Immunoblot of II showed one broad zone over the mol.wt. range 65-70,000. The average assay values obtained in human plasma specimens from 10 males were 85 micrograms/ml for HMWK (range 65-130) and 174 micrograms/ml for LMWK (range 164-183). HMWK occasionally lost immunoreactivity during purification without a corresponding loss of kinin. Such a loss of immunoreactivity seemed to run parallel with a reduced release of kinin induced by hog pancreas kallikrein.

Reduced or unchanged cofactor function of human high molecular weight kininogen induced by human plasma kallikrein

Plasma kallikrein activated spontaneously during the purification of prekallikrein (I) and acetone-activated plasma kallikrein (II) were at pH 7.4 both capable of reducing the capacity of purified human high molecular weight kininogen (HMrK) to function as cofactor in the contact phase activation of factor XII in a crude plasma preparation. At pH 6.8 only I had such an effect. SDS polyacrylamide gel electrophoresis with reduction indicated that both I and II contained kallikrein as a cleaved 'three-chain molecule. I contained in addition a Mr 49,000 fraction reflecting possibly uncleaved heavy chain. The registration of reduced cofactor function of HMrK induced by plasma kallikrein is discussed in view of the assay procedure used.

Reduced cofactor function of human high molecular weight kininogen induced by human plasma kallikrein

Most reports in the literature state that human plasma kallikrein does not destroy the capacity of human high molecular weight kininogen (HMrK) to function as a cofactor in the contact phase activation of factor XII. In the present work preparations of highly purified human plasma kallikrein that showed high plasminogen activator (PGA) activities rapidly reduced the cofactor function of human HMrK. Gel electrophoresis with SDS without reduction showed that all kallikrein preparations tested contained two protein bands, one major band with a Mr of about 83,000, and one weak band with a Mr of 80,000. The main band is probably identical with kallikrein I, which Levison & Tomalin (1982b), using Ac-Pro-Phe-Arg-OMe-HCl as substrate, found to be ten times more active (in terms of kcat/Km) than kallikrein II with Mr 3000 daltons lower. The rate of HMrK destruction in our experiments varied with the kallikrein preparation used, but assays of their hydrolytic activities against benzoyl arginine ethylester (BAEe) or the plasma kallikrein selective tripeptide substrate H-D-Pro-Phe-Arg-pNA (S-2302) did not discriminate between enzyme preparations with different HMrK-destroying capacities. Assay of PGA activities demonstrated a correlation between the level of PGA measured, and the HMrK-destroying capacity.

Activation of factor XII in human plasma: protection by benzamidine of the cofactor function of high molecular weight kininogen

By incubation of human citrated plasma with acetone 25% v/v kallikrein inhibitors were destroyed and prekallikrein activated to kallikrein. When the incubation was carried out in the presence of benzamidine 7 mM, the cofactor capacity of high molecular weight kininogen (HMrK) was protected against destruction by a serine protease which was not plasma kallikrein. By analogy with studies in rat plasma this protease might be a plasminogen activator (Berstad & Briseid 1982; Johansen & Briseid 1983). Factor XII in the plasma preparation was activated to unfragmented factor XIIa by adsorption to kaolin, and assayed as prekallikrein activator (PKA). The extent of activation of factor XII was only insignificantly influenced by the 1 + 1 (v/v) dilution of the plasma preparation with a suspension of kaolin. When, however, the preparation was diluted greater than 1 + 5 (v/v) before incubation with the suspension, a stoichiometric HMrK concentration-effect curve could be established, allowing the assay of cofactor-active HMrK. Assays of HMrK in plasma preparations from healthy men and women demonstrated an average lower level of cofactor-active HMrK in the preparations from women. It is suggested that benzamidine is not capable of providing a complete protection of HMrK during the procedure in all plasma samples.