Laurence Bonhomme-Faivre

MDR-1 C3435T polymorphism influences cyclosporine a dose requirement in liver-transplant recipients.

Background. Cyclosporine A (CsA) is characterized by high interindividual variations in oral bioavailability and a narrow therapeutic index. CsA is a substrate for P-glycoprotein, a member of the ABC transporter family encoded by the multiple drug-resistant gene MDR1. Methods. Because MDR1 gene exon 26 C3435T polymorphism influences intestinal P-glycoprotein expression, we investigated whether this polymorphism was correlated with variation in CsA dose requirement and concentration/dose ratio in 44 liver-transplant recipients during 1 month after transplantation. CsA concentration was measured 2 hours after administration (C2), according to international recommendations. Results. The MDR-1 wild-type genotype (3435CC) was observed in 15 patients (34%), whereas 21 (48%) patients were heterozygous (3435CT), and 8 (18%) patients were homozygous for the mutation (3435TT). There was no significant difference between the three groups regarding corticosteroids treatment or renal function during this period. One to 3 days after liver transplantation, when every patient received a similar CsA weight-adjusted dose, the concentration/dose ratio was correlated with exon 26 single nucleotide polymorphism and was significantly higher in subjects homozygous for the mutation (P=0.012). This was confirmed 1 month after transplantation (P=0.049), when the dose was adjusted to maintain the C2 target level of 1,000 &mgr;g/L and we observed that TT patients required approximately 50% lower weight-adjusted CsA dose than wild-type patients (P=0,033). Conclusions. These findings demonstrate that the MDR1 exon 26 C3435T polymorphism is a major determinant of CsA concentration/dose ratio in liver-transplant recipients and is predictive of the dose of CsA to be administered to achieve the target C2 concentration.

Practical management of boceprevir and immunosuppressive therapy in liver transplant recipients with hepatitis C virus recurrence.

ABSTRACT Hepatitis C virus (HCV) recurrence is the most important complication in HCV liver transplant patients. Boceprevir with pegylated interferon and ribavirin (PegIFN/RBV) enabled improvement in sustained virological response rates of patients with genotype 1 HCV. Boceprevir interacts with immunosuppressive therapy (IT) by inhibiting the cytochrome P450 3A enzyme. Our aim was to study interactions and assess the safety of boceprevir in the context of HCV recurrence. Boceprevir (800 mg three times a day) initiated after a 4-week lead-in phase was associated with cyclosporine (three patients), tacrolimus (two patients), and everolimus (one patient) in five liver transplant patients with genotype 1 HCV infection who experienced HCV recurrence. The mean follow-up period after HCV therapy was 14.8 ± 3.1 weeks. Estimated oral clearances of IT decreased on average by 50%, requiring reduced dosing regimens. Anemia occurred in all patients, with a mean fall in hemoglobin levels between baseline and week 12 of 3.12 ± 2.27 g/dl. All patients required administration of β-erythropoietin (n = 5), three needed ribavirin dose reduction, and one needed a blood transfusion. A virological response was observed in all patients (mean HCV viral load [HVL] decrease at week 12, 6.64 ± 0.35 log10 IU/ml). These preliminary results in liver transplant patients with HCV recurrence demonstrate the feasibility and safety of coadministration of boceprevir and IT.

Effect of Highly Active Antiretroviral Therapy on Tacrolimus Pharmacokinetics in Hepatitis C Virus and HIV Co-Infected Liver Transplant Recipients in the ANRS HC-08 Study

ObjectiveTo characterise the interactions between tacrolimus and antiretroviral drug combinations in hepatitis C virus-HIV co-infected patients who had received a liver transplant.DesignAn observational, open-label, multiple-dose, two-period, one-sequence design clinical trial in which patients received tacrolimus as an immunosuppressive therapy during the postoperative period and then had an antiretroviral drug regimen added. Tacrolimus pharmacokinetics were evaluated at steady state during these two periods.MethodsFourteen patients participated in the study and seven participated in the intensified pharmacokinetic protocol. Patients were included if they had undergone liver transplantation for end-stage chronic hepatitis C, absence of opportunistic infection, a CD4 cell count of >150 cells/μL and an undetectable HIV plasma viral load (<50 copies/mL) under highly active antiretroviral therapy. During the posttransplantation period, the tacrolimus dose was adjusted according to blood concentrations. When liver function and the tacrolimus dose were stable, antiretroviral therapy was reintroduced.ResultsWhen lopinavir/ritonavir were added to the tacrolimus regimen (seven patients), the tacrolimus dose was reduced by 99% to maintain the tacrolimus concentration within the therapeutic range. Only two patients were treated with nelfinavir, which led to a wide variation in inhibition of tacrolimus metabolism. When efavirenz (four patients) or a nucleoside analogue combination (one patient) was added, very little change in tacrolimus dosing was required.ConclusionThe lopinavir/ritonavir combination markedly inhibited tacrolimus metabolism, whereas the effect of efavirenz was small. Tacrolimus dosing must be optimised according to therapeutic drug monitoring and the antiretroviral drug combination.

Alterations of biological parameters in mice chronically exposed to low-frequency (50 HZ) electromagnetic fields

In an experimental study we measured changes in hematological, biochemical and cortisol parameters in 6-week-old Swiss mice continuously exposed to ELF generated by a transformer station and high current bus bars. Mean daily exposure of 5.0 microT was maintained for 350 days. Hematological parameters were compared to those of control mice (n=12) exposed to a field level lower than 0.1 microT. Serum biochemical parameters (sodium, potassium, chloride, calcium, magnesium, phosphorus, amylase, creatine phosphokinase, and lactate dehydrogenase) were measured after 28 days of exposure and serum cortisol after 90 and 190 days. Granulocyte/macrophage colony-forming cells (GM-CFC) were counted at the end of the 350-day exposure. On day 20, exposed animals showed a significant decrease in leukocyte, erythrocyte, lymphocyte and monocyte counts and in hemoglobin and hematocrit values, while MCV increased. On days 43 and 63 no significant difference was observed in leukocyte and erythrocyte values, as if hemopoiesis had recovered. On day 90, a significant fall in the leukocyte, polynuclear neutrophil and eosinophil counts was observed in the exposed animals. No significant difference was noted in the biochemical parameters studied. On day 190, exposed animals had neutropenia and a decrease in the cortisol value. On day 350, no significant difference in hematological parameters was noted. Individual differences in sensitivity were observed, as 8 mice in the exposed group showed a significant decrease in the leukocyte, polymorphonuclear neutrophil and GM-CFC counts, while in two mice there was a significant increase in these same values compared to those unexposed mice.

Study of human neurovegetative and hematologic effects of environmental low-frequency (50-Hz) electromagnetic fields produced by transformers.

A survey of neurovegetative and hematologic disorders was conducted in a population (n = 13) exposed occupationally to environmental electromagnetic fields; the population was matched with 13 control subjects. The exposed subjects worked at least 8 h/d for 1-5 y in premises located above transformers and high-tension cables, and the subjects were submitted to low-frequency electromagnetic fields (i.e., 50 Hz) of 0.2 microT-6.6 microT. The subjects were matched with respect to socioeconomic category, sex, and age with a control population of subjects that worked in premises outside of the immediate vicinity of transformers or high-tension cables. The exposed population had a significant increase in degree of certain neurovegetative disorders (i.e., physical fatigue, psychical asthenia, lipothymia, decreased libido, melancholy, depressive tendency, and irritability). In addition, the population experienced a significant fall in total lymphocytes and CD4, CD3, and CD2 lymphocytes, as well as a rise in NK cells. Leukopenia and neutropenia were also observed in two persons permanently exposed to doses of 1.2-6.6 microT. The disorders disappeared when exposure stopped, and they reappeared on reexposure.

Effects of Electromagnetic Fields on the Immune Systems of Occupationally Exposed Humans and Mice

The authors examined immunological disorders in 6 individuals who had been exposed occupationally to environmental electromagnetic fields. Comparable effects on mice exposed in a similar environment were also investigated. The human subjects had worked 8 hr/day for 5 yr in a laboratory located above electrical transformers and high-tension cables, and in which there were low-frequency electromagnetic fields of 0.2-6.6 microtesla (μT). The 6 control subjects (matched for socioeconomic parameters, sex, and age) had worked away from the immediate vicinity of transformers and high-tension cables. The authors found statistically significantly lower total lymphocyte, CD4, and CD3 counts, and significantly increased natural killer (NK) cells, in exposed subjects vs. controls. Six months after exposure had ceased, total lymphocyte counts had increased, as had CD4, CD3, and CD19 counts (+13%, +28%, +22%, and +17%, respectively), and NK cell counts were decreased by 26% (not significant) in the same human subjects. In the second part of this study, 12 Swiss male mice housed in cages were exposed in the same room in which the human subjects had been exposed (i.e., 5-μT, 50-Hz magnetic field) for 109 days; 12 additional mice were used as unexposed controls. The total lymphocyte, leukocyte, polymor-phonuclear neutrophil, CD4, and NK counts of the exposed mice at 109 days were significantly lower than those of controls. In addition, plasma glucose levels (at 30 days) and amylase activity (at 109 days) were significantly lower, whereas plasma sodium and chloride levels were significantly elevated at 109 days. Results from this study suggest that chronic exposure to a 0.2-6.6-μT magnetic field can lead to decreased immunological parameters (total lymphocytes and CD4 counts) in both humans and mice. The increase in some values once exposure was terminated suggests a causal relationship with exposure to electromagnetic fields, as do the changes in mice, particularly the changes in total lymphocyte and CD4 counts.

Recombinant interleukin-2 treatment decreases p-glycoprotein activity and paclitaxel metabolism in mice

Recombinant rIL-2 was reported to be able to decrease P-glycoprotein (P-gp) expression in cultured cells from human colon carcinoma. P-gp is considered an important factor in the control of Taxol® efflux from tumor cells. Based on the premise that Taxol pharmacokinetic parameters could be modified as a result of diminished P-gp expression induced by recombinant interleukin (rIL)-2 and that this might elicit an interaction between the two drugs, we evaluated the pharmacokinetics of a novel strategy combining i.p. immunotherapy with rIL-2 and a cytotoxic agent, Taxol. Mice were allocated to two groups treated with rIL-2 (15 μ g×2/day from day 1 to 4) then Taxol (10 mg/kg i.p. day 5) or Taxol (10 mg/kg i.p.) alone (control group). The Taxol + rIL-2 combination provoked the development of ascites, presumably due to the presence of Cremophor EL in the Taxol preparation. Paclitaxel was measured in plasma and ascites by HPLC with UV detection. Paclitaxel pharmacokinetics were strongly modified by rIL-2 pretreatment. Compared to that observed in control mice, the apparent volume of distribution increased dramatically (Vd/F = 18.2 versus 4.1 l/kg) and the apparent plasma clearance decreased (Cl/F = 1.12 versus 1.66 l/h/kg). P-gp expression was determined in the liver, lung, intestine, brain and kidney in the two groups by immunodetection with the C219 anti-P-gp monoclonal antibody. A significant decrease in P-gp expression was observed in the intestine and in the brain in the rIL-2-pretreated mice as compared to controls. To study the functionality of P-gp, we compared digoxin (a model P-gp substrate) pharmacokinetics before and after pretreatment with rIL-2 (10 μ g×2/day from day 1 to 4), after a single 1 μ g oral dose of digoxin used to quantify P-gp activity. Results showed a decrease in oral digoxin clearance after rIL-2 pretreatment indicating modified P-gp activity. We conclude that rIL-2 pretreatment is able to decrease P-gp activity and paclitaxel metabolism in vivo. This is the first study to demonstrate a decrease in P-gp activity and expression in organs such as the brain in vivo. A novel strategy combining immunotherapy with rIL-2 and a cytotoxic agent could potentially improve clinical results, particularly in brain cancer.

PRECLINICAL STUDY: Disposition of Δ9 tetrahydrocannabinol in CF1 mice deficient in mdr1a P-glycoprotein

P‐glycoprotein (P‐gp) plays a major role in drug efflux. All the transported substrates are more or less hydrophobic and amphiphatic in nature. Being lipophilic, Δ9 tetrahydrocannabinol (THC), the main cannabis component, could be a potential P‐gp substrate. The aim of this project was to determine the contribution of the mdr1a gene product to THC disposition. Therefore, oral THC and digoxin (substrate test for P‐gp) pharmacokinetics have been investigated in the intestinal epithelium and in the brain capillary endothelium of CF1 mdr1a (−/−) mice (mice naturally deficient in P‐gp). These pharmacokinetics were compared to THC and digoxin oral pharmacokinetics in wild type mice mdr1a (+/+) (not P‐gp deficient). The application of Bailers method showed that THC total exposure measured by the area under the plasma concentration time curve was 2.17‐fold higher in CF1 mice naturally deficient in P‐gp than in wild type mice after oral administration of 25 mg/kg of THC, and 2.4‐fold higher after oral administration of 33 µg/kg of digoxin. As a consequence, the oral bioavailability of THC and digoxin was higher in naturally P‐gp‐deficient mice. We concluded that P‐gp limits THC oral uptake and mediates direct drug excretion from the systemic circulation into the intestinal lumen.

SYMPTOMS EXPERIENCED BY USERS OF DIGITAL CELLULAR PHONES: A STUDY OF A FRENCH ENGINEERING SCHOOL

A survey study, using a questionnaire, was conducted in 161 students and workers in a French engineering school on symptoms experienced during use of digital cellular phones. A significant increase in concentration difficulties (p<.05) was reported by users of 1800-MHz (DCS) cellular phones compared to users of 900-MHz (GSM) cellular phones. In users of cellular phones, women significantly (p<.05) complained more often of sleep disturbance than men. The use of both cellular phones and VDT significantly (p<.05) increased concentration difficulties. Digital cellular phone users also significantly (p<.05) more often complained of discomfort, warmth, and pricking of the ear during phone conversations as a function of calling duration per day and number of calls per day.

Significance of isolated hepatic veno-occlusive disease/sinusoidal obstruction syndrome after liver transplantation.

After liver transplantation (LT), hepatic veno‐occlusive disease (VOD), which is also known as sinusoidal obstruction syndrome (SOS), has been reported initially in relation to azathioprine use and subsequently in relation to acute rejection (AR). Isolated veno‐occlusive disease (iVOD)/SOS raises some questions about its significance and especially its treatment. From the post‐LT biopsy samples of 1364 patients (2000‐2008), 31 patients with index biopsy samples showing VOD/SOS (2.3%) were identified. After a review of the index biopsy samples and previous biopsy samples, those patients not exposed to azathioprine therapy were subdivided into 2 groups according to the absence or presence of AR. Fifteen of the 31 patients had no previous evidence of AR, whereas 16 experienced episodes of AR (before or concurrently with VOD). The 2 groups were similar in terms of demographic and clinical data and the range of histological centrilobular changes. AR episodes were characterized by an endothelial predilection. iVOD/SOS occurred later than acute rejection–related veno‐occlusive disease (AR‐VOD)/SOS (mean times of 65 and 4.4 months, respectively, P = 0.0098). There was a tendency for iVOD/SOS to progress less frequently to chronic rejection in comparison with AR‐VOD/SOS (3/15 versus 9/15, P = 0.06). The histological resolution of iVOD/SOS was significantly more frequent in patients who benefited from increased immunosuppression in comparison with those who did not (5/7 versus 2/8, P = 0.05). When the groups were considered together, the same result was obtained (14/18 versus 4/12, P = 0.024). In conclusion, despite a constant overall prevalence of VOD/SOS, the proportion of iVOD/SOS has increased. The histological resolution of iVOD/SOS after increase in immunosuppression suggests an immune‐mediated origin. Better optimization of immunosuppression may be a curative treatment. Liver Transpl 17:798‐808, 2011.