Adverse Events under Tacrolimus and Cyclosporine in the First 3 Years Post-Renal Transplantation in Children

Neutropenia in pediatric solid organ transplant

Neutropenia is generally defined as an absolute neutrophil count in the circulation of less than 1500/mm³ and occurs in up to 25%-30% of pediatric solid organ transplant recipients (SOT) within the first year after transplantation. In the SOT population, neutropenia is most often a result of drug-induced bone marrow suppression but can also be secondary to viral infection, nutritional deficiencies, lymphoproliferative infiltrate, and inherited causes. Outcomes for patients with neutropenia vary by degree of neutropenia and type of solid organ transplant. Management of neutropenia should begin by addressing the underlying cause, including reducing or removing medications when appropriate, treating infections, and addressing nutrient deficiencies; however, consultation with an experienced pediatric hematologist and use of granulocyte colony-stimulating factor (G-CSF) may be helpful in some cases. Overall, data on clinical outcomes for G-CSF use remain limited, but observational studies may support its use in patients with infections or severe neutropenia.

Effects of tacrolimus on autophagy protein LC3 in puromycin-damaged mouse podocytes

Objective

To investigate the mechanism through which tacrolimus, often used to treat refractory nephropathy, protects against puromycin-induced podocyte injury.

Methods

An in vitro model of puromycin-induced podocyte injury was established by dividing podocytes into three groups: controls, puromycin only (PAN group), and puromycin plus tacrolimus (FK506 group). Podocyte morphology, number, apoptosis rate and microtubule associated protein 1 light chain 3 alpha (LC3) expression were compared.

Results

Puromycin caused podocyte cell body shrinkage and loose intercellular connections, but podocyte morphology in the FK506 group was similar to controls. The apoptosis rate was lower in the FK506 group versus PAN group. The low level of LC3 mRNA observed in untreated podocytes was decreased by puromycin treatment; however, levels of LC3 mRNA were higher in the FK506 group versus PAN group. Although LC3-I and LC3-II protein levels were decreased by puromycin, levels in the FK506 group were higher than the PAN group. Fewer podocyte autophagosomes were observed in the control and FK506 groups versus the PAN group. Cytoplasmic LC3-related fluorescence intensity was stronger in control and FK506 podocytes versus the PAN group.

Conclusions

Tacrolimus inhibited puromycin-induced mouse podocyte damage by regulating LC3 expression and enhancing autophagy.

Metformin and silymarin afford protection in cyclosporine A induced hepatorenal toxicity in rat by modulating redox status and inflammation

The use of cyclosporine A (CsA) as an immunosuppressive agent is often limited owing to its hepatotoxic and nephrotoxic properties. The present study was designed to evaluate the protective effect of metformin and silymarin in a rat model of CsA induced hepatorenal toxicity. The study included seven groups of Wistar albino rats (n = 6 per group): normal control, experimental control (CsA alone, 25 mg/kg), CsA + metformin (50 and 500 mg/kg), CsA + silymarin (50 and 200 mg/kg) and CsA + vitamin E (100 mg/kg). All the drugs were given daily for a period of 21 days by oral gavage and their effect was evaluated on serum levels of organ function markers (serum glutamate pyruvate transaminase, serum glutamate oxaloacetate transaminase, bilirubin, urea/blood urea nitrogen, creatinine), markers of oxidative stress (thiobarbituric acid reactive substances, glutathione, superoxide dismutase), inflammation (nitrite, myeloperoxidase, tumour necrosis factor-alpha, prostaglandin E₂ ), apoptosis (terminal deoxynucleotidyl transferase dUTP nick end labelling positivity) in addition to tissue histology, cyclooxygenase (COX)-2 and inducible nitric oxide synthase (iNOS) immunoreactivity. Administration of metformin and silymarin along with CsA ameliorated functional damage to liver and kidneys in a dose-dependent manner. Significant and comparable improvement in the tissue levels of oxidative stress, inflammation, apoptotic markers was also observed following treatment with both the test drugs. Normalization of histology scores, as well as COX-2 and iNOS immunoreactivity scores, further strengthened these findings. The hepatoprotective and nephroprotective effects of metformin and silymarin were comparable and matched with that of reference drug, vitamin E. The findings of the present study suggest that both metformin and silymarin have a potential for clinical use in patients receiving long-term CsA treatment to maintain their liver and kidney functions.

Tacrolimus: Influence of the Posttransplant Concentration/Dose Ratio on Kidney Graft Function in a Two-Year Follow-Up

INTRODUCTION

Tacrolimus (TAC) metabolism rate has the potential to impact graft function after kidney transplantation (KTx). We aimed to analyze the relationship between the early post-KTx TAC C/D ratio (blood trough concentration normalized by total daily dose) and kidney graft function in a 2-year follow-up.

METHODS

We retrospectively analyzed data from 101 post-KTx patients at 3, 6, 12, and 24 months after KTx to identify the C/D ratio cutoff value optimal for dividing patients into fast and slow TAC metabolizers. We investigated the relationship between their TAC metabolism rate and graft function.

RESULTS

Patients were divided based on the TAC C/D ratio at 6 months after KTx of 1.47 ng/mL * 1 mg. Fast metabolizers (C/D ratio <1.47 ng/mL * 1 mg) presented with significantly worse graft function throughout the whole study period (p < 0.05 at each timepoint) and were significantly less likely to develop good graft function (estimated glomerular filtration rate ≥45 mL/min/1.73 m2) than slow metabolizers. Our model based on donor and recipient age, recipient sex and slow/fast metabolism status allowed for identification of patients with compromised graft function in 2-year follow-up with 66.7% sensitivity and 94.6% specificity.

CONCLUSION

Estimating TAC C/D ratio at 6 months post-KTx might help identify patients at risk of developing deteriorated graft function in a 2-year follow-up.

Blood eosinophils and IgE levels among umbilical cord transplantation recipients with food allergies

The use of immunosuppressive treatments and their related gastrointestinal adverse effects have been implicated in the development of food allergic responses following transplantation. There is limited information on the pathogenesis of the food allergic immune response among umbilical cord transplantation recipients. This study was conducted to identify a cohort of food allergic umbilical cord recipients in the literature. The literature was searched to systematically identify this cohort. Criteria for inclusion included umbilical cord transplantation, food allergic response, and reported laboratory data. Analysis of the laboratory data using the Pearson method revealed that there was a moderate negative correlation with a coefficient of r=−0.7016 and r²=−0.49 between peripheral eosinophilia and serum immunoglobulin E (IgE) levels. Future studies on a larger population are needed, but this study may help to elucidate possible cellular mechanisms involved in this response.

Switching Immunosuppression From Cyclosporine to Tacrolimus in Kidney Transplant Recipients Based on CYP3A5 Genotyping

BACKGROUND

Kidney transplant recipients on long-term cyclosporine (CsA) therapy may develop multiple adverse drug events, and immunosuppression conversion from CsA to tacrolimus (Tac) is an option. Genetic variations, especially cytochrome P450 (CYP) 3A5*3, affects Tac dosing. However, little information is available to guide the conversion with regards to patients' pharmacogenomics. We aimed to investigate whether CYP3A5, CYP3A4, and ABCB1 genotyping could contribute to a more precise and individualized initial dosing of Tac at the time of immunosuppressant conversion.

METHODS

Genotypes of 5 candidate genes (CYP3A5*3, CYP3A4*1G, ABCB1C1236T, ABCB1C3435T, and ABCB1G2677T/A) were investigated by polymerase chain reaction and restriction fragment-length polymorphism methods in 46 adult kidney transplant recipients requiring immunosuppressant conversion from CsA to TAC. Associations between these functional genetic polymorphisms and the dose-adjusted trough concentrations of CsA and Tac were evaluated, retrospectively.

RESULTS

Based on the linear regression analysis, CYP3A5 expressers (*1/*1 and *1/*3) had lower Tac dose-adjusted trough concentrations on days 7, 14, 21, and 28, and they required 1.40- to 1.75-fold higher daily dose to reach the target concentration compared with nonexpressers (*3/*3) on day 28 [0.07 (0.06-0.09) mg/kg/d versus 0.05 (0.02-0.06) mg/kg/d, P = 0.001]. CYP3A4*1G or ABCB1 genetic polymorphisms had no effect on the Tac dose-adjusted trough concentrations.

CONCLUSIONS

Our preliminary study supports the use of CYP3A5 genotyping to guide the initial dosing of Tac when converting the immunosuppression therapy from CsA to Tac.