Activation of bovine bradykininogen by human plasmin

Activities of plasminogen activator, plasmin and kallikrein in synovial fluid from patients with temporomandibular joint disorders

To measure the activities of plasminogen activator (PA), plasmin and kallikrein, multiple synovial fluid samples were taken from 32 patients with internal derangement (ID) and osteoarthrosis (OA), and nine asymptomatic volunteers. The enzyme activity in synovial fluid from the temporomandibular joint (TMJ) was quantitated by a fluorogenic substrate assay using an enzyme substrate. In fluid samples from the patient group, PA was detected in 24 (31.5%), plasmin in 20 (26.3%) and kallikrein in 53 (96.4%), while none of these enzymes were found in the synovial fluid samples from the control group. There were positive correlations found among PA, plasmin and kallikrein. These results clearly demonstrated increased levels of PA, plasmin and kallikrein activities in the synovial fluid of patients with ID and OA, and suggest that these enzymes may be involved in the pathogenesis of synovitis, as well as the resorption of cartilage and bone in TMJ.

Stimulation of plasminogen activator activity and matrix metalloproteinases of human dental pulp-derived cells by tumor necrosis factor-alpha

The effects of tumor necrosis factor (TNF)-alpha on the plasminogen activator (PA)/plasmin system in human dental pulp (HDP) cells were examined. TNF-alpha treatment induced a significantly high level of PA activity in the conditioned medium of HDP cells in a time- and dose-dependent manner, compared with untreated control cells. Western-blot analysis revealed that tissue type (t)PA protein in conditioned medium was increased by TNF-alpha when compared with control medium. Furthermore the tPA mRNA level had increased in HDP cells treated with TNF-alpha, as determined by reverse transcription-polymerase chain reaction, but urokinase PA and PA inhibitor-1 mRNA levels did not increase. We examined the effects of TNF-alpha against activities of matrix metalloproteinases (MMPs) using zymography. TNF-alpha stimulated MMP-2 activity in conditioned medium and stimulated MMP-9 activity with addition of plasminogen into conditioned medium. The present results suggested that TNF-alpha stimulates PA activity via an enhancement of tPA gene expression in HDP cells and MMP-2 activity, and further that tPA-activated TNF-alpha stimulated MMP-9.

Stimulation of plasminogen activator/plasmin system in gingival fibroblast cells by oxygen radicals

The effect of extracellular oxygen radicals on cultured gingival fibroblast cells (Gin cells) was investigated in the plasminogen activator (PA)/plasmin system. The activation of the PA/plasmin system in Gin cells exposed to a sublethal oxygen radical [hypoxanthine (HX) 0.1 mg ml-1/xanthine oxidase (XOD) 5 munit ml-1] system was examined. Following a 1 h exposure, washed cells were cultured for up to 24 h in fresh medium containing 2% fetal calf serum. The exogenous addition of superoxide dismutase, an oxygen radical scavenger, abolished the PA/plasmin activity enhanced by the HX/XOD system. The PA produced by Gin cells was found to be urokinase-type PA (uPA), as preincubation of Gin cell-conditioned medium with anti-uPa serum completely inhibited PA activity. These findings suggest that extracellular oxidant targetting to Gin cells may be involved in the progression of inflammation and the invasion of periodontium through stimulation of the PA/plasmin system.

Kallikrein-kinin system in chronic subdural haematomas: its roles in vascular permeability and regulation of fibrinolysis and coagulation

The kallikrein-kinin system is closely related to both fibrinolysis and coagulation, and bradykinin--the end product of this system--is a powerful mediator which increases vascular permeability. In the present study, to test the hypothesis that the kallikrein-kinin system plays a part in the aetiology of chronic subdural haematomas, components of this system (prekallikrein, high molecular weight kininogen (HMW-kininogen), and bradykinin), and those of the fibrinolytic and coagulation systems were measured at 134 haematoma sites in 119 patients. The activities of prekallikrein and HMW-kininogen in the haematomas were significantly lower than those in the plasma of the patients, and showed a parallel decrease. The bradykinin concentration in the haematomas was significantly higher than that in the plasma. These results indicate activation of the kallikrein-kinin system in chronic subdural haematomas. The activation of both fibrinolysis and coagulation was also shown, and there was a significant correlation between HMW-kininogen and plasminogen, fibrin/fibrinogen degradation products, or platelets in the haematomas. This suggests regulation of fibrinolysis and coagulation by the kallikrein-kinin system or mutual stimulation of these systems. In the outer membrane, perivascular haemorrhage, interstitial oedema, and leucocyte migration were evident microscopically, indicating an increase in vascular permeability. The protein concentration in the haematomas was significantly higher than that in the peripheral blood, indicating plasma exudation from the capillaries in the outer membrane. The activation of the kallikrein-kinin system, by increasing vascular permeability, may cause blood extravasation and plasma exudation from the capillaries into both the outer membrane and the haematoma cavity, resulting in enlargement of the haematoma.

Effect of Campylobacter rectus LPS on plasminogen activator-plasmin system in human gingival fibroblast cells

The plasminogen activator (PA)-plasmin system is implicated in the degradation of the extracellular matrix in inflammation through activation of metalloproteases and prekallikrein. We examined the activation of the PA-plasmin system in human gingival fibroblast cells (Gin-1 cells) following treatment with lipopolysaccharide (LPS) from Campylobacter rectus, which is frequently detected at sites of periodontal disease. The C. rectus LPS stimulated the plasmin activity in the conditioned medium of Gin-1 cells in a time- and dose-dependent manner, and C. rectus LPS also stimulated the PA activity in the conditioned medium. The PA produced by Gin-1 cells was determined to be urokinase PA (uPA), as preincubation of Gin-1 conditioned medium with anti-uPA antiserum completely inhibited the PA activity while that with anti-tPA antiserum had no inhibitory effect. The concentration of PA inhibitor-1 (PAI-1) in the conditioned medium was decreased by the addition of C. rectus LPS. Therefore, the enhancement of plasmin activity in the conditioned medium was dependent on increased uPA activity via the decrease of the PAI-1 level of Gin-1 cells treated with C. rectus LPS. Furthermore, the conditioned medium of Gin-1 cells treated with C. rectus LPS showed significantly increased kallikrein activity, indicating the conversion of prekallikrein to kallikrein, which converts kininogen into kinin. These findings suggest that C. rectus LPS is a potent stimulator of inflammation of gingival tissue which acts through stimulation of the PA-plasmin system.

Stimulation of plasmin activity in cultured human fibroblast cells by Porphyromonas endodontalis

1. Plasmin activity in the conditioned medium of Gin-1 cells, a human gingival fibroblast cell line, was stimulated by Porphyromonas endodontalis, a putative pathogen of oral submucous abscesses, in a time- and dose-dependent manner. 2. P. endodontalis stimulated the activity of plasminogen activator in both the conditioned medium and the cell lysate. The plasminogen activator in Gin-1 cells was approx. 50 kDa by zymography. 3. The conditioned medium of Gin-1 cells exposed to P. endodontalis stimulated the conversion of human serum prekallikrein to kallikrein. 4. These results suggested that P. endodontalis stimulates the plasminogen activator-plasmin system in Gin-1 cells, and that activated plasmin plays a role in the progress of periodontal tissue inflammation.

Modulation of natural and interleukin-2-induced tumour-cytolytic activities by the members of a protein family related to beta-thromboglobulin

A preparation of three C-terminal fragments of the platelet protein beta-thromboglobulin was previously described to have immunomodulatory properties on phagocytic cells. One of the components is obviously identical to the recently described neutrophil-activating peptide 2 (NAP-2). In further investigations on this protein preparation (called factor C) we are able to show an additional influence on the tumour-cytolytic activities of mononuclear cells. Total neutralization of the factor C effect, by treating a factor C preparation with specific monoclonal antibody C24 prior to application in cell culture, proved that the effect is really restricted to factor C proteins. If factor C is given in combination with natural interleukin-2 (IL-2) a dose-dependent suppression of IL-2-mediated natural killer lymphokine-activated killer activity can be measured, which is first detectable 72 h after addition of factor C. Suppression does not occur if the both factors are added within a time interval of more than 12 h. Depletion of monocytes from mononuclear cells has no effect on factor-C-mediated cytotoxicity, demonstrating that factor C acts directly on lymphoid cells.

Fibrinolytic activity in periodontal disease. The relationship between fibrinolytic activity and severity of periodontal disease

IN RECENT YEARS, evidence has evolved that suggests a relationship between fibrinolytic phenomenon and various inflammatory diseases. Plasmin activity and the response of the fibrinogen and fibrin degradation products latex test (FDPL test) in gingival fluid, along with plasminogen activator activity in gingival tissue were assessed. Samples were taken from periodontally involved persons and compared with healthy individuals. The following conclusions could be drawn: (1) The fluid from inflamed gingival crevices possessed more plasmin activity than that from clinically healthy crevices. The reaction of the FDPL test was stronger in the former. (2) Plasminogen activator activity in gingival tissue showed no significant difference between periodontally involved and healthy subjects.