Amedea Silvia Tirelli

Influence of the Cyp3a5 genotype on tacrolimus pharmacokinetics and pharmacodynamics in young kidney transplant recipients

Abstract:  CYP3A enzyme plays a pivotal role in TAC metabolism. The aim of this study was to analyze retrospectively the influence of CYP3A5 gene polymorphism on TAC pharmacokinetics and pharmacodynamics in 30 teenage kidney transplant recipients. TAC dose, trough blood levels, apparent volume of distribution, as well as blood pressure and antihypertensive therapy obtained at different post‐transplant periods, were correlated with the corresponding genotype. Despite a therapeutic monitoring strategy, heterozygotes (CYP3A5*1/*3) displayed a lower TAC blood concentration compared with homozygotes (CYP3A5*3/*3). Therefore, a two‐fold increase of the daily TAC dose was required in the heterozygotes to reach the desired therapeutic target level. A significant group by time interaction effect was present for both variables (repeated measures anova: p = 0.002) meaning a significant different pharmacokinetic response in these two cohorts. Mean blood pressure was also elevated in CYP3A5*1/*3 recipients despite similar antihypertensive treatment. This was parallel with an elevated apparent volume of distribution of TAC in this group. Thus, the allele‐effect was correlated with one of the most common TAC side‐effects suggesting a possible influence of CYP3A5 polymorphism on TAC pharmacodynamics. The authors concluded that a pre‐emptive CYP3A5 pharmacogenetic screening could contribute to better individualization of TAC therapy.

Vitamin D Deficiency and Infertility: Insights From in vitro Fertilization Cycles

CONTEXT Vitamin D deficiency has been proven to affect fertility in mammals, but data in human is less convincing. In particular, data on in vitro fertilization (IVF), an attractive model to draw information on this topic, are sparse and conflicting. OBJECTIVE Our objective was to investigate IVF outcome in women with deficient 25-hydroxy-vitamin D [25(OH)D] serum levels (<20 ng/mL). DESIGN AND SETTING This prospective cross-sectional study was conducted at the infertility unit of an academic setting. PATIENTS The main inclusion criteria were as follows: (1) indication to IVF, (2) age 18-42 years, (3) BMI 18-25 kg/m(2), (4) adequate ovarian reserve according to Bologna criteria. Eligible women provided a serum sample for 25(OH)D measurement at the time of cycle preparation. Subjects were subsequently excluded if the cycle was cancelled or if the attempt was excessively delayed. INTERVENTION Quantitative detection of serum 25(OH)D. MAIN OUTCOME MEASURE Clinical pregnancy rate. RESULTS The number of recruited women with serum 25(OH)D <20 ng/mL and ≥ 20 ng/mL was 154 and 181, respectively. The clinical pregnancy rates were 20% (30/154) and 31% (56/181), respectively (P = .02); the adjusted odds ratio for clinical pregnancy in women with vitamin D ≥ 20 ng/mL was 2.15 (95% CI: 1.23-3.77). Subgroup analyses showed that the group of women with the highest serum levels (>30 ng/mL) had the highest chances of pregnancy. CONCLUSIONS Vitamin D is an emerging factor influencing female fertility and IVF outcome. Additional studies are pressingly needed to confirm a causal relationship and to investigate the potential therapeutic benefits of vitamin D supplementation.

Acute pyelonephritis as a cause of hyponatremia/hyperkalemia in young infants with urinary tract malformations

Obstructive uropathy causes tubular resistance to aldosterone and severe metabolic imbalance may be precipitated by an episode of pyelonephritis. In the last 3 years we investigated 52 episodes of pyelonephritis (positive urine culture, elevated C reactive protein, fever, elevated neutrophil count) in 50 children between 15 days and 15 months of age. Ultrasonography voiding cystography and renal scintiscan were performed in all cases and iv urography in some. A salt‐losing syndrome with hyponatremia and hyperkalemia (Na <125 meq/liter; K >6.3 meq/liter) was observed in 17 infants <3 months, accompanied by plasma aldosterone concentration of 5000 to 23 000 pg/ml (normal value, <1000 pg/ml). All these children had a severe urinary tract (UT) malformation (ureteropelvic junction stenosis in 7 cases, vesicoureteral reflux in 7, posterior urethral valves in 2, double system in 1). Thirteen infants <3 months, 7 with no urinary tract malformations, did not have electrolyte imbalance. Pyelonephritis was diagnosed in 20 other patients ages 4 to 15 months, including 16 with severe UT malformations; 4 had normal UTs. We conclude that a salt-losing syndrome with tubular resistance to aldosterone can occur during pyelonephritis in young infants with congenital UT malformation, that the risk diminishes considerably or disappears after 3 months of age and that in the absence of UT malformation pyelonephritis does not cause acute sodium loss of clinical relevance.

Frequencies and roles of CYP3A5, CYP3A4 and ABCB1 single nucleotide polymorphisms in Italian teenagers after kidney transplantation.

The main genes involved in the pharmacokinetics of immunosuppressive drugs are those encoding cytochrome P450 (CYP) family enzymes and multidrug resistance 1 (ABCB1). In this study, 87 Italian teenagers with transplanted kidneys (mean age 11.6 ± 4.8 years) receiving calcineurin inhibitors (CNIs) were genotyped for the single nucleotide polymorphisms (SNPs) CYP3A5*1/3 and CYP3A4*1B for CYP3A, and C1236T, G2677T/A, C3435T and IVS21+49 for ABCB1, and retrospectively evaluated for the influence of the screened SNPs on CNI blood level at different post-transplantation times. The CYP3A5*1 allele was present in 7% of the patients, and the CYP3A4*1B allele was present in 3% of patients. The ABCB1 C1236T, G2677T/A and C3435T SNPs C, G and T occurred frequently (55%, 53% and 54%, respectively). The frequency of the T allele of IVS21+49 was 86%. The frequency of SNPs in both genes was comparable with that reported in other European Caucasian populations but different from that found in Asians or Afro-Americans. None of the cyclosporine (CsA) pharmacokinetic parameters were associated with the CYP3A5 genetic polymorphism, whereas the presence of the A allele in some patients was responsible for the required administration of a significantly increased dose of tacrolimus (Tac) that was necessary to reach therapeutic target levels. None of the Tac pharmacokinetic parameters were associated with ABCB1 SNPs, but ABCB1 SNPs had early effects on the CsA exposure index and dose requirements. In conclusion, because SNPs of the CYP3A and ABCB1 genes may be associated with CNI pharmacokinetic parameters and exposure indices, pre-transplant genetic screening should be considered in order to avoid immunosuppressant-related adverse events.

Analysis of inflammatory and immune response biomarkers in sputum and exhaled breath condensate by a multi-parametric biochip array in cystic fibrosis.

Cystic Fibrosis (CF) lung disease is characterized by high levels of cytokines and chemokines in the airways, producing chronic inflammation. Non-invasive biomarkers, which are also specific for the inflammatory and immune responses, are urgently needed to identify exacerbations and evaluate therapeutic efficacy. The aim of this study is to evaluate the association of sputum and exhaled breath condensate (EBC) biomarker changes with clinical exacerbation and response to therapy. We studied the simultaneous presence and concentration of twelve cytokines and growth factors (EGF, IL-1α, IL-1β, IL-2, IL-4, IL-6, IL-8, IL-10, IFN-γ, MCP-1, TNF-α and VEGF) by a multi-parametric biochip array in sputum and EBC of 24 CF patients before, after 6 and 15 days of therapy, and 15 days after the end of treatment for an acute exacerbation. Correlations with functional respiratory tests (FEV1, FVC) and the systemic marker C-reactive protein (CRP) were looked for. In sputum, before therapy, VEGF and IL-1β levels positively correlated with the respiratory function and CRP. Sputum IL-1α, IL-1β IL-4, IL-10, TNF-α, and VEGF significantly decreased, while EGF increased, during therapy. IL-8 and IL-4 levels negatively correlated with the respiratory function at 15 and 30 days from the start of therapy, respectively. IL-4, IL-6, IL-10 and TNF-α positively correlated with CRP during therapy. Although some EBC biomarkers correlated with respiratory function and CRP, no significant associations with these clinical parameters were found. Sputum IL-1β and VEGF might be considered biomarkers of an acute exacerbation in CF patients. A panel of sputum cytokines and growth factors may better describe the response to intravenous antibiotic treatment of CF than one single systemic marker.

Nutrients Intake Is Associated with DNA Methylation of Candidate Inflammatory Genes in a Population of Obese Subjects

The aim of the present study was to evaluate the potential association between dietary nutrients and alterations in DNA methylation in a set of five candidate genes, including CD14, Et-1, iNOS, HERV-w and TNFα, in a population of overweight/obese subjects. We evaluated possible associations between gene methylation and clinical blood parameters, including total cholesterol (TC), low- and high-density lipoprotein cholesterol (LDL-C and HDL-C), triglyceride and homocysteine levels. We employed validated methods to assess anthropometric, clinical and dietary data, as well as pyrosequencing to evaluate DNA methylation of the five candidate genes in 165 overweight/obese subjects. There was no association between body mass index and DNA methylation of the five candidate genes in this group of subjects. Positive associations were observed between TNFα methylation and blood levels of LDL-C (β = 0.447, p = 0.002), TC/HDL-C (β = 0.467, p = 0.001) and LDL-C/HDL-C (β = 0.445, p = 0.002), as well as between HERV-w methylation and dietary intakes of β-carotene (β = 0.088, p = 0.051) and carotenoids (β = 0.083, p = 0.029). TNFα methylation showed negative associations with dietary intakes of cholesterol (β = −0.278, p = 0.048), folic acid (β = −0.339, p = 0.012), β-carotene (β = −0.332, p = 0.045), carotenoids (β = −0.331, p = 0.015) and retinol (β = −0.360, p = 0.008). These results suggest a complex relationship among nutrient intake, oxidative stress and DNA methylation.

Insulinlike growth factor 1 in controls and growth-retarded fetuses

Objectives: To establish a reference range of insulinlike growth factor 1 (IGF-1) values in normal fetuses and to assess whether intrauterine growth retardation is associated with increased or decreased IGF-1 levels. Methods: Retrospective analysis of blood samples collected from 64 fetuses who underwent blood sampling at 18–38 weeks’ gestation was performed: 40 fetuses, who were considered controls, were appropriately grown for gestational age and were found unaffected by the condition for which they were tested; the remainder (n = 24) underwent fetal blood sampling to assess fetal karyotype and acid-base balance following ultrasonic diagnosis of intrauterine growth retardation. (In this group, 8 survived, and 16 died during the perinatal period). IGF-1 was measured using a radioimmunoassay after acid-ethanol extraction in order to avoid interference by the binding proteins. All samples from controls and growth-retarded fetuses were measured using the same batch, and the intra-assay coefficient of variation of the test ranged from 4.1 to 6.1%. Results: In control fetuses, IGF-1 serum levels increased linearly with gestational age. In growth-retarded fetuses, IGF-1 levels were not significantly different from the reference range (median Z-score –0.3; range –4.4 to 291) and did not correlate with fetal size, hematocrit, and acid-base balance values. There was a significant difference in IGF-1 and pH values when the fetuses were divided into two groups based on the perinatal outcome: those who survived had values of IGF-1 mostly within the normal range, whereas the fetuses who died in utero or postnatally had significantly decreased pH and elevated IGF-1 values (median Z-score 2.1; 95% confidence interval 0.4–13.9; p = 0.04). Conclusions: This study confirms previous observations that IGF-1 levels parallel the increase in fetal size which occurs with advancing gestation. Increased levels of IGF-1 may indicate a terminal process in the fetal adaptation to placental failure.

Proximal tubular function and hyperfiltration during amino acid infusion in man

The relations between renal hemodynamics (Inutest, CPAH) and sodium segmental handling (sodium distal delivery, distal reabsorption, and fractional excretion) were studied in 9 healthy adults infused with an isotonic amino acid solution and in 6 subjects infused with 0.9% saline for 3 h at 0.2 ml/min/kg. During all tests maximal water diuresis was induced and maintained to effect analysis of sodium segmental transport. Both types of infusion produced a similar expansion of extracellular volume (weight increase, hematocrit fall, suppressed plasma renin activity and plasma aldosterone). The amino acid infusion increased the glomerular filtration rate (GFR) and renal blood flow without modifying the filtration fraction. With saline no hemodynamic modifications were observed. The expansion with saline depressed proximal and distal sodium reabsorption whereas during amino acid infusion sodium distal delivery was unaltered and the significantly increased sodium fractional excretion was sustained only by depressed distal reabsorption. Therefore, in parallel with the GFR increase, closely dependent on renal vasodilatation, the well-known stimulation of sodium cotransport by amino acids is able to antagonize the effects of expansion on the proximal sodium reabsorption. An explanation of glomerular hyperfiltration based on a primary metabolic stimulation of the proximal tubular function is suggested.

The potential of steroids and xenobiotic receptor polymorphisms in forecasting cyclosporine pharmacokinetic variability in young kidney transplant recipients.

Ferraresso M, Turolo S, Belinghieri M, Tirelli AS, Grillo P, Groppali E, Edefonti A, Ghio L. The potential of steroids and xenobiotic receptor polymorphisms in forecasting cyclosporine pharmacokinetic variability in young kidney transplant recipients.

Association Between CYP3A5 Polymorphisms and Blood Pressure in Kidney Transplant Recipients Receiving Calcineurin Inhibitors

Abstract Renal cytochrome P450 3A5 (CYP3A5) has been associated with blood pressure (BP) control in humans. We investigated whether CYP3A5 polymorphisms are associated with post- transplant hypertension in a selected population of kidney recipients receiving calcineurin inhibitors. Ninety-two kidney transplant recipients receiving cyclosporine (CyA) or tacrolimus (Tac) were genotyped for CYP3A5 polymorphisms, and the association between the CYP3A5 alleles (*1,*3) and hypertension on post-operative day (POD) 6 and POD 180 was verified, with multiple regression being used to identify the putative co-variates that may predict the extent and severity of hypertension in transplant recipients at different post-transplant times. The CYP3A5*1 carriers had higher systolic (SBP) and diastolic blood pressure (DBP) in both the immediate and delayed post-transplant period when adjusted for anti-hypertensive medication (POD 6: SBP = 161 ± 23 vs. 140 ± 23 mmHg; DBP = 120 ± 15 vs. 87 ± 14 mmHg, p < 0.05. POD 180: SBP = 136 ± 16 vs. 129 ± 14 mmHg; DBP = 89 ± 15 vs. 80 ± 15 mmHg, p < 0.05). The severity of hypertension between the CYP3A5*1 carriers and noncarriers on POD 6 was documented by the significantly different distribution of hypertension classes, but this was not confirmed on POD 180. The CYP3A5 genotype was the only independent variable affecting mean arterial pressure. The results of this study show that CYP3A5 polymorphisms are associated with the severity and degree of hypertension in kidney transplant recipients receiving calcineurin inhibitors regardless of the time of recording. However, the role of concomitant medications such as steroids with strong CYP3A5 inducing activity, should be taken into account.