Association Between Gene Polymorphisms of the Components of the Renin-Angiotensin-Aldosteron System, Graft Function, and the Prevalence of Hypertension, Anemia, and Erythrocytosis After Kidney Transplantation

Pre-transplant angiotensin II receptor type I antibodies in pediatric renal transplant recipients: An observational cohort study

BACKGROUND

The role of angiotensin II type 1 receptor antibodies (AT1R-Ab) in pediatric renal transplantation is unclear. Here, we evaluated pre-transplant AT1R-Ab on transplant outcomes in the first 5 years. Secondary analysis compared pre-transplant AT1R-Ab levels by age.

METHODS

Thirty-six patients, 2-20 years old, were divided into two groups: pre-transplant AT1R-Ab- (<17 U/ml; n = 18) and pre-transplant AT1R-Ab+ (≥17 U/ml; n = 18). eGFR was determined at 6-month, 1-, 2-, and 4-year post-transplant. Allograft biopsies were performed in the setting of strong HLA-DSA (MFI > 10 000), AT1R-Ab ≥17 U/ml, and/or elevated creatinine.

RESULTS

Mean age in pre-transplant AT1R-Ab- was 13.3 years vs. 11.0 in pre-transplant AT1R-Ab+ (p = 0.16). At 6 months, mean eGFR was 111.3 ml/min/1.73 m² in pre-transplant AT1R-Ab- vs. 100.2 in pre-transplant AT1R-Ab + at 1 year, 103.6 ml/min/1.73 m² vs. 100.5; at 2 years, 98.9 ml/min/1.73 m² vs. and 93.7; at 4 years, 72.6 ml/min/1.73 m² vs. 80.9. 11/36 patients had acute rejection (6 in pre-transplant AT1R-Ab-, 5 in pre-transplant AT1R-Ab + ). There was no difference in rejection rates. All 6 subjects with de novo HLA-DSA and AT1R-Ab ≥17 U/ml at the time of biopsy experienced rejection. Mean age in those with the AT1R-Ab ≥40 U/ml was 10.0 years vs. 13.2 in those <40 U/ml (p = 0.07).

CONCLUSION

In our small cohort, pre-transplant AT1R-Ab ≥17 U/ml was not associated with reduced graft function or rejection. The pathogenicity of pre-transplant AT1R-Ab in pediatric kidney transplantation requires further investigation.

Association between Angiotensin I-Converting Enzyme Insertion/Deletion Polymorphism and Prognosis of Kidney Transplantation: A Meta-Analysis

PURPOSE

Angiotensin I-converting enzyme (ACE) is crucial in the renin-angiotensin-aldosterone system. ACE insertion/deletion (I/D) polymorphism is a common genetic variation of this gene and is associated with several disease phenotypes. However, the results of published studies on the influence of this polymorphism on renal transplantation are inconsistent. Therefore, a meta-analysis was performed to evaluate the association between ACE I/D polymorphism and prognosis of kidney transplantation.

METHODS

A meta-analysis was performed based on 21 case-control studies from 12 publications (1497 cases and 2029 controls) and 10 studies with quantitative values from 5 publications (814 patients). Pooled odds ratios (ORs) and weighted mean differences (WMDs) with their corresponding 95% confidence intervals (CIs) were used to estimate associations.

RESULTS

ACE I/D polymorphism was found to be associated with acute rejection (AR) in genotypes DD+ID versus II (OR = 1.62, 95% CI = 1.14-2.29) and with serum creatinine concentration after renal transplantation in genotypes DD versus ID (WMD = 13.12, 95% CI = 8.09-18.16). Stratified analysis revealed that recipients transplanted within a year had higher serum creatinine concentrations in the DD versus ID model. No significant association was found between hypertension and ACE I/D polymorphism.

CONCLUSION

ACE I/D polymorphism is associated with AR and allograft function after kidney transplantation.

Post-renal transplant erythrocytosis: a case report

PTE is defined as hematocrit >51% or hemoglobin >17 g/dL after renal transplantation. Risk factors include native kidneys with adequate erythropoiesis pretransplant, smoking, renal artery stenosis, and cyclosporine treatment. We report the case of a 14-yr-old female kidney transplant patient, with triple therapy immunosuppression and stable graft function who developed PTE at 12 months post-transplant with hemoglobin 17.3 g/dL, hematocrit 54.2%, stable graft function, and normotensive with normal cardiac echocardiogram and erythropoietin levels. The only risk factor found was tobacco use. As she had no spontaneous improvement, enalapril treatment was started at 19 months post-transplant with a hemoglobin level of 17.5 g/dL and hematocrit 53%; by 23 months post-transplant, hemoglobin lowered to 15 g/dL and hematocrit to 44.5% and continued to be in normal range thereafter. PTE is a rare condition in childhood and can be successfully treated with enalapril.