Involvement of group VI Ca2+-independent phospholipase A2 in protein kinase C-dependent arachidonic acid liberation in zymosan-stimulated macrophage-like P388D1 cells.

We investigated the possible involvement of group VI Ca2+-independent phospholipase A2 (iPLA2) in arachidonic acid (AA) liberation in zymosan-stimulated macrophage-like P388D1 cells. Zymosan-induced AA liberation was markedly inhibited by methyl arachidonoyl fluorophosphonate, a dual inhibitor of group IV cytosolic phospholipase A2 (cPLA2) and iPLA2. We found that a relatively specific iPLA2 inhibitor, bromoenol lactone, significantly decreased the zymosan-induced AA liberation in parallel with the decrease in iPLA2 activity, without an effect on diacylglycerol formation. Consistent with this, attenuation of iPLA2 activity by a group VI iPLA2 antisense oligonucleotide resulted in a decrease in zymosan-induced prostaglandin D2 generation. These findings suggest that zymosan-induced AA liberation may be, at least in part, mediated by iPLA2. A protein kinase C (PKC) inhibitor diminished zymosan-induced AA liberation, while a PKC activator, phorbol 12-myristate 13-acetate (PMA), enhanced the liberation. Bromoenol lactone suppressed the PMA-enhanced AA liberation without any effect on PMA-induced PKC activation. Down-regulation of PKCalpha on prolonged exposure to PMA also decreased zymosan-induced AA liberation. Under these conditions, the remaining AA liberation was insensitive to bromoenol lactone. Furthermore, the PKC depletion suppressed increases in iPLA2 proteins and the activity in the membrane fraction of zymosan-stimulated cells. In contrast, the zymosan-induced increases in iPLA2 proteins and the activity in the fraction were facilitated by simultaneous addition of PMA. Although intracellular Ca2+ depletion prevented zymosan-induced AA liberation, the translocation of PKCalpha to membranes was also inhibited. Taken together, we propose that zymosan may stimulate iPLA2-mediated AA liberation, probably through a PKC-dependent mechanism.

[Significance of urinary fibrin/fibrinogen degradation product (FDP) D-dimer measured by highly sensitive ELISA method with a new monoclonal antibody (D-D E72) in various renal diseases].

In order to clarify the abnormalities of the coagulation and fibrinolysis system in patients with various renal diseases, we produced a new monoclonal antibody for FDP (fibrin/fibrinogen degradation product) D-dimer (D-D E72). We also established a new highly sensitive method of enzyme-linked immunosorbent assay (ELISA) for urinary FDP D-dimer using this monoclonal antibody. The urine from 110, patients with various renal diseases was investigated for the FDP D-dimer. The results are summarized as follows: 1) Urinary FDP D-dimer in normal subjects was 0.69 +/- 0.60 ng/ml. 2) The level of urinary FDP D-dimer in patients with primary nephrotic syndrome and in patients with chronic renal failure was significantly higher than that of normal subjects, whereas the urinary FDP D-dimer levels in patients with diabetes mellitus were higher than those of normal subjects. 3) In the CGN and NS groups there was a tendency for an increase in the level of urinary FDP D-dimer in more active forms of the disease. 4) A significant correlation between urinary FDP D-dimer and urinary protein in the CGN and NS groups was demonstrated. 5) In all of the renal diseases investigated in this study, the ratio of urinary FDP D-dimer to total FDP was less than 4%.

[Molecular marker for detecting hypercoagulable state].

We measured various coagulable factors and molecular markers in plasma and serum in the disease group including DIC, DIC suspect, thrombosis, acute myocardial infarction, angina pectoris, sepsis, malignant tumor and type II diabetes and the healthy subject group, and surmised the intravascular coagulative-fibrinolytic activity in each disease group compared with the healthy group. Additionally we selected parameters useful for early detection of the pre-thrombotic state and hypercoagulable state. As a result, of the parameters for the coagulative system, those considered useful were the assay of soluble fibrin monomer complexes using the synthetic substrate (FM.Oita), assay of soluble fibrin monomer complexes using HPLC(SFMC.Oita) and thrombin-anti-thrombin III complex (TAT) in this order. Of the parameters for the fibrinolytic system, those considered useful were FDP assay using ELISA (FDP.Oita) and plasmin-alpha 2 plasmin inhibitor complex (PIC). This FDP.Oita had a considerably high detection sensitivity compared with the FDP assay (Diayatron Co.) using the latex photometric immunoassay which has been commercially available. When measurement was made with plasma and serum in the subject disease group as the sample by the high sensitivity assays mentioned above, it was made clear that both the coagulative activity and fibrinolytic activity are increased, albeit with some differences in intensity, in all the disease groups compared with the healthy group. In order for the hypercoagulable state and pre-thrombotic state to be detected, it is important to know the balance between the coagulative activity and fibrinolytic activity. According to the results of the present experiment, a significant directly proportional correlation was recognized between FM.Oita and FDP.Oita and between TAT and FDP.Oita. Therefore, examination of these ratios will be a more detailed indicator of coagulative-fibrinolytic activity than the TAT/PIC ratio, PAI-1/TPA ratio and ATIII/alpha 2 PI ratio hitherto in use. If useful molecular markers such as FM.Oita are measured over time in various cases and these data are compiled and analyzed statistically, it will not be long before the criteria for the hypercoagulable state and pre-thrombotic state are established.