Yoshiharu Sakamoto

Increased T‐Helper‐1‐Type Immunity and Decreased T‐Helper‐2‐Type Immunity in Patients with Preeclampsia

PROBLEM: To examine whether preeclampsia involves type‐1 T‐helper (Th1) immune hyperactivity.

Characterization of Human Placental Activity for Transport of L-alanine, Using Brush Border (Microvillous) Membrane Vesicles

The uptake of taurocholate into brush border membrane vesicles prepared from human full term placenta was studied using a rapid filtration technique. The taurocholate uptake into brush border membrane vesicles was sensitive to extravesicular osmolarity, and pre-incubation of the brush border membrane vesicles with the taurocholate increased the uptake of taurocholate into the brush border membrane vesicles. These findings indicate that the uptake of taurocholate by brush border membrane vesicles represents transport into vesicles. The uptake of taurocholate into vesicles was not dependent on Na+ electrochemical gradient (extravesicular > intravesicular). But this uptake was markedly increased when the intravesicular space was rendered electrically more positive by the use of lowly permeant anions or valinomycin-induced K+ diffusion membrane potentials. These findings indicate that the taurocholate transport into brush border membrane vesicles was dependent on membrane potential. The initial rate of taurocholate transport into brush border membrane vesicles exhibited saturation kinetics with respect to the taurocholate concentration, an apparent Km of 67 microM and Vmax of 0.30 nmol/mg protein/20 sec were calculated.

Suppression of Urokinase Receptor Expression by Thalidomide Is Associated with Inhibition of Nuclear Factor κB Activation and Subsequently Suppressed Ovarian Cancer Dissemination

Thalidomide has been used to treat a variety of diseases ranging from alleviation of autoimmune disorders to prevention of metastasis of cancers. It has been shown previously that increased levels of urokinase-type plasminogen activator receptor (uPAR) correlate well with higher invasive phenotype. We examined whether thalidomide is able to suppress the expression of uPAR mRNA and protein in human ovarian cancer cell line HRA and human chondrosarcoma cell line HCS-2/8. Here, we show that: (a) thalidomide suppresses the expression of constitutive and transforming growth factor-beta1 (TGF-beta1)-induced uPAR mRNA and protein; (b) a nuclear factor kappaB (NF-kappaB) activation system (phosphorylation of IkappaB-alpha and degradation of IkappaB-alpha) is necessary for the TGF-beta1-induced increase in uPAR expression, because L-1-tosylamido-2-phenylethyl chloromethyl ketone, a NF-kappaB inhibitor, reduced the uPAR production as well as mRNA expression; (c) thalidomide failed to further strengthen L-1-tosylamido-2-phenylethyl chloromethyl ketones action; (d) the once-daily i.p. administration of thalidomide (400 microg/g body weight/d) decreased progressive growth of HRA tumors and ascites formation in an in vivo animal model; and (e) the once-daily i.p. administration of thalidomide in combination with paclitaxel (i.p., 100 microg/20 g at days 2 and 5) significantly decreased progressive growth of HRA cells in a synergistic fashion. We conclude that thalidomide down-regulates constitutive and TGF-beta1-stimulated uPAR mRNA and protein expression possibly through suppression of NF-kappaB activation. Furthermore, combination therapy with thalidomide plus paclitaxel may be an effective way to markedly reduce i.p. tumor growth and ascites in ovarian cancer dissemination.

Platelet aggregation inhibiting activity of human placental chorioepithelial brush border membrane vesicles.

We investigated the platelet aggregation inhibiting activity of human placental brush border membrane vesicles (BBMV) and obtained the following results. A strong platelet aggregation inhibiting activity existed in placental BBMV. The BBMV inhibited the platelet aggregation induced by ADP, arachidonic acid, collagen and ristocetin in a dose-dependent manner. The protein concentration of BBMV giving 50 per cent inhibition was 52 +/- 6 micrograms/ml for ADP-induced platelet aggregation, 21 +/- 2 micrograms/ml for arachidonic acid-induced platelet aggregation, 19 +/- 2 micrograms/ml for collagen-induced platelet aggregation and 107 +/- 9 micrograms/ml for ristocetin-induced platelet aggregation. There was a high level of ADP degrading activity (ADPase activity) in the placental BBMV. ADP degrading activity of the BBMV: 10.5 +/- 0.5 mumol/mg protein/min was 21 times greater than that of homogenate of the placental villi. The placental BBMV inhibited platelet TXA2 production. In the 40 micrograms/ml protein concentration of placental BBMV, platelet TXA2 production was almost completely inhibited.

Platelet aggregation inhibiting activity of human placental chorioepithelial brush border membrane vesicles: the role of alkaline phosphatase

Human placental chorioepithelial brush border membrane, which is in direct contact with maternal blood flow, has platelet aggregation inhibiting activity. In the present study, the mechanism of this action has been examined in relation to ADP (adenosine diphosphate) degrading activity and alkaline phosphatase activity of brush border membrane vesicles (BBMV). BBMV prepared from human early and term placental villi, inhibited platelet aggregation induced by ADP. BBMV had potent ADP degrading (ADPase) activity. ADP was quickly degraded by BBMV. ADP degrading activity of BBMV was not so different between early and term placenta. Alkaline phosphatase activity of late placental BBMV was about three times greater than that of early placental BBMV. On the other hand, ADP degrading activity of late placental BBMV was almost the same as that of early placental BBMV. Inhibiting activity of platelet aggregation induced by ADP and ADP degrading activity of BBMV, were not inhibited by levamisole (alkaline phosphatase inhibitor).

Studies on placental inhibition of platelet aggregation: A comparison of human syncytiotrophoblast brush border and basal plasma membranes

We compared the platelet aggregation inhibiting activity of human placental syncytiotrophoblast brush border membrane vesicles (BBMV) and basal plasma membrane vesicles (BpMV), and obtained the following results. Strong platelet aggregation inhibiting activity is found in placental BBMV. BBMV inhibited platelet aggregation induced by ADP (adenosine diphosphate) and arachidonic acid in a way which depended on the protein concentration of BBMV added. In contrast, BpMV showed no detectable platelet aggregation inhibiting activity. Quite high ADP degrading activity (ADPase activity) was present in the placental BBMV. ADP was quickly degraded by BBMV. In contrast, BpMV did not degrade ADP so quickly. Platelet TXB2 production was almost completely abolished at the protein concentration of 40 micrograms/ml of BBMV. In contrast, BpMV did not significantly inhibit platelet TXA2 (TXB2) production. These results show that syncytiotrophoblast brush border and basal plasma membranes of the human placenta have markedly different properties with respect to platelet aggregation inhibiting activity.