Jing-Ding Wang

Changes in lipid metabolism and effect of simvastatin in renal transplant recipients induced by cyclosporine or tacrolimus

Hyperlipidemia is frequently developed following renal transplantation and results in worsening of the patients prognosis. In study 1, the effects of immunosuppressants, cyclosporine (CsA) and tacrolimus on serum lipids were compared in-patients undergoing renal transplantation. The study included 32 cases of renal transplantation recipients who randomized to the CsA treatment group (15 patients) and the tacrolimus group (17 patients). Before and 1 month after the transplantation, we assessed the serum lipid levels, apolipoprotein levels, the concentrations of cholesterol in the respective lipoprotein fractions and the enzyme activities related to lipid-metabolism. The serum lipid levels in both groups were significantly increased at 1 month after renal transplantation. In the CsA group, there were significant increases in cholesterol contents in very-low-density lipoprotein (VLDL), LDL2 and HDL2 fractions, whereas, in the tacrolimus group, cholesterol content was increased in VLDL and HDL2 fractions. In study 2, 1 month after renal transplantation, 19 patients with hypercholesterolemia (total cholesterol (TC) >200 mg/dl) and hypertriglyceridemia (triglyceride (TG) >150 mg/dl) were treated with simvastatin 5-10 mg/day for 6 months. Simvastatin treatment significantly decreased serum TC (240+/-29-200+/-22 mg/dl, P<0.001), low-density lipoprotein cholesterol (LDL-C; 114+/-20-99+/-17 mg/dl, P<0.05) and TG levels (217+/-103-130+/-38 mg/dl, P<0.01). In addition, there were significant decreases in very-low-density lipoprotein cholesterol (VLDL-C; 53+/-20-34+/-15 mg/dl, P<0.001). The Cmax and AUC of simvastatin were increased about eight-fold, when simvastatin was given in combination with CsA. In contrast, no significant changes in simvastatin levels were observed when combination with tacrolimus. Although simvastatin levels were increased with CsA, there were no abnormal changes in renal and liver functions, creatinine phosphokinase (CPK) levels or in incidence of adverse effects.

Early induction of apoptosis in androgen‐independent prostate cancer cell line by FTY720 requires caspase‐3 activation

We previously reported that FTY720, a metabolite from Isaria sinclairii, induced some cancer cells to undergo apoptosis, and that FTY720‐induced apoptosis was not related to Fas‐antigens. In this study we investigated whether FTY720 was able to induce apoptosis in an androgen‐independent prostate cancer cell line, DU145, which is not only resistant to androgen‐withdrawal‐induced apoptosis but also Fas‐ and TNF‐α‐mediated apoptosis.

Anticarcinogenic effect of FTY720 in human prostate carcinoma DU145 cells: Modulation of mitogenic signaling, FAK, cell‐cycle entry and apoptosis

Despite the high frequency of prostate cancer, therapeutic options for advanced disease are limited to chemotherapy, radiation or hormonal therapy and eventually fail in all patients. Therefore, alternative approaches need to be developed. We previously reported that FTY720, a metabolite from Isaria sinclarii, is a unique antitumor agent for an androgen‐independent prostate cancer cell line and requires caspase‐3 activation in apoptosis. In our study, we have evaluated the effect of FTY720 on a family of mitogen‐activated protein kinases (MAPKs), focal adhesion kinase (FAK), mitochondrial transmembrane potential, caspase‐9 and caspase‐8 and analyzed the expression of some cell‐cycle regulator proteins in DU145 cells in order to understand the various antitumor effects of FTY720. Apoptosis was quantified by phosphatidylserine exposure. Activation of MAPKs, cleavage of caspase‐9 and caspase‐8, status of cyclin‐dependent kinases (CDKs) and Cip1/p21, a cyclin‐dependent kinase inhibitor, were evaluated by Western blot analysis, in addition to FAK and phospho‐FAK immunoprecipitation and cell‐cycle analysis by FACScan. We found that in DU145 cells, 40 μM FTY720 caused activation of p38 MAPK and the upstream kinase MKK3/MKK6 but not SAPK/JNK. Mitochondrial transmembrane potential, FAK and ERK1/2 were reduced while caspase‐9 and caspase‐8 were cleaved. The p38‐specific inhibitor had no effect on apoptosis induced by FTY720, whereas z‐VAD.FMK, a broad‐spectrum caspase inhibitor, did not inhibit the p38 MAPK activation. An amount of 20 μM FTY720 resulted in G1 arrest and a decrease of CDK2 as well as CDK4, whereas it induced Cip1/p21. FTY720 may exert anticarcinogenic effects against prostate cancer cells possibly involving modulation of mitogenic signaling, cell‐cycle regulators, induction of G1 arrest and apoptotic death in DU145 cells.

A novel immunosuppressive drug, FTY720, prevents the cancer progression induced by cyclosporine

Cyclosporine A (CsA), the most frequently used immunosuppressive drug, has been reported to induce cancer by a cell-autonomous mechanism. Herein, we report that FTY720, a novel immunosuppressant, prevents CsA-induced alterations in both morphology and cell motility at a low concentration (0.1 microM) and induces the CsA-treated cancer cells to undergo apoptosis at a higher concentration (more than 5 microM). The inhibitory activity of FTY720 is unrelated to the decrease of TGF-beta. We believe that a combination treatment with FTY720 and CsA not only results in a synergistic effect on allografts, but also, reduces the incidence of cancer in transplant patients.

Rapid and simple determination of mycophenolic acid in human plasma by ion-pair RP-LC with fluorescence detection

Mycophenolic acid (MPA) is an immunosuppressive drug given as the prodrug of mycophenolate mofetil (MMF). In order to investigate the pharmacokinetics of MPA, a simple, specific, sensitive and reliable method has been established for the quantitative determination of MPA in plasma from renal transplant recipients. The method involves a single-step protein precipitation procedure and a specific determination by ion-pair reversed-phase high-performance liquid chromatography (HPLC) with fluorescence detection. Separation was achieved on a C18 column (150 x 4.6 mm, 5 microm) with a mobile phase composed of borate buffer (pH 10.0; 50 mM)--acetonitrile--tetrabutylammonium bromide (200 mM) (75:25:1, v/v/v). The fluorescence detector was set at 310 (excitation) and 430 nm (emission). Following protein precipitation with ice-cold acetonitrile, clear supernatants (50 microl) were injected into the HPLC system. The retention time of MPA was approximately 4.5 min. The HPLC run time was 8 min. The assay was linear in concentration range 0.2-20.0 microg/ml for MPA in human plasma. Precision of the assay in the concentration range examined was from 0.89 to 3.21% for the intra-assay run and from 3.01 to 4.35% for the inter-assay run. A limit of detection was 0.05 microg/ml at a signal-to-noise ratio of 3. This validated method was then applied to the determination of MPA concentrations in renal transplant recipients after oral administration of 0.75 g of MMF.

Lymphotactin: a key regulator of lymphocyte trafficking during acute graft rejection.

The attraction of leucocytes to allografts is essential for rejection. The prcocess is controlled by chemokines. In order to clarify the role of lymphotactin (a cytokine that represents a novel branch of the chemokine superfamily) in regulating leucocyte trafficking during graft rejection, we used rat renal transplantation models to examine its gene expression and the distribution of lymphotactin‐expressing cells in renal grafts. Lymphotactin mRNA was upregulated strongly in acutely rejecting renal allografts. The mRNA was undetectable in isografts, chronically rejecting renal allografts or normal kidney. Once lymphotactin was expressed, large numbers of infiltrating lymphocytes were seen. Moreover extended studies demonstrated that in cultured rat spleen cells the expression of lymphotactin mRNA was markedly induced by phytohaemagglutinin (PHA) or phorbol myristate acetate (PMA), and such induction was inhibited by the immunosuppressive drugs FK506 and cyclosporin. Collectively, these observations provide new evidence demonstrating that lymphotactin is a key regulator of lymphocyte motility and adhesiveness during acute allograft rejection. FK506 and cyclosporin inhibition of lymphotactin expression is likely to represent an important molecular mechanism of the action of the drugs.

Rapid and simultaneous determination of mycophenolic acid and its glucuronide conjugate in human plasma by ion-pair reversed-phase high-performance liquid chromatography using isocratic elution

A high-performance liquid chromatographic method has been developed for the simultaneous determination of mycophenolic acid (MPA) and its glucuronide conjugate (MPAG) in human plasma. The method involves protein precipitation with acetonitrile, followed by ion-pair reversed-phase chromatography on C18 column, with a 40 mM tetrabutyl ammonium bromide (TBA)-acetonitrile (65:35, v/v) mobile phase. A 20-microl volume of clear supernatant was injected after centrifugation, and the eluent was monitored at 304 nm. No interference was found either with endogenous substances or with many concurrently used drugs, indicating a good selectivity for the procedure. Calibration curves were linear over a concentration range of 0.5-20.0 microg/ml for MPA and 5-200 microg/ml for MPAG. The accuracy of the method is good, that is, the relative error is below 5%. The intra- and inter-day reproducibility of the analytical method is adequate with relative statistical deviations of 6% or below. The limits of quantification for MPA and MPAG were lower than 0.5 and 5.0 microg/ml, respectively, using 50 microl of plasma. The method was used to determine the pharmacokinetic parameters of MPA and MPAG following oral administration in a patient with renal transplantation.

Pharmacokinetics and lipid-lowering effect of fluvastatin in hypercholesterolaemic patients on maintenance haemodialysis.

Patients undergoing haemodialysis are predisposed to serum lipid abnormalities that can accelerate the development of atherosclerosis. Serum lipid levels must therefore be controlled over a long period. For patients with reduced renal function (including dialysis patients), special attention must be paid to hyperlipidaemia therapy, particularly drug selection. In this study, 30 mg/day fluvastatin was administered orally to five patients receiving maintenance haemodialysis. Their serum lipid levels and blood biochemistry were monitored during the 6 months of fluvastatin administration, and the pharmacokinetic parameters calculated. The therapeutic efficacy and safety of fluvastatin were demonstrated in this patient group. Furthermore, fluvastatin is not influenced by the dialysis membrane and does not accumulate in haemodialysis patients with hyperlipidaemia.

Clinocopathological evaluation in non-episode biopsies of renal transplant allograft

Abstract Histopathological findings in renal allograft with stable function remain unclear. We therefore performed non‐episode biopsy in the long‐surviving renal allograft to investigate the histopathological changes. Our data show that, although arteriolopathy is characteristic of drug‐induced nephropathy, it is unrelated to dosage and concentration of cyclosporine or tacrolimus in non‐episode biopsy. We evaluated therefore the clinicopathological findings of arteriolopathy in this study. Non‐episode biopsy was defined as follows: as serum creatinine level lower than, 2.0 mg/dl and a urinary protein level lower than 500 mg/day. A total of 65 biopsy specimens were enrolled in this study as non‐episode biopsy. Twenty‐nine specimens revealed arteriolopathy. There were no statistically significant differences between arteriolopathy and dosage or concentration of cyclosporine or tacrolimus. Arteriolopathy in non‐episode biopsy was related to time of biopsy, kidney age, hypertension, and hyperlipidemia, suggesting that it is important for graft survival to strictly control blood pressure and blood lipid level.

The differences between late graft loss group and long‐term graft survival group in renal transplantation

Tanaka T, Takahara S, Hatori M, Toki K, Wang J‐D, Permpongkosol S, Yazawa K, Kokado Y, Oka K, Kyo M, Okuyama A, Yamanaka H. The differences between late graft loss group and long‐term graft survival group in renal transplantation. Clin Transplantation 2001: 15 (Supplement 5): 16–21. ©Munksgaard, 2001