90 - Angiotensin II Type 1 Receptor Antibodies and Native Renal Function in Pediatric Liver and Intestinal Transplant Recipients

Poster Number: 90
Publication Number: 90.138

Rachel Stern, UCLA Mattel Childrens Hospital, LOS ANGELES, CA, United States; Lucia Chen, University of California, Los Angeles David Geffen School of Medicine, Culver City, CA, United States; Alvin Chan, UCLA Mattel Children's Hospital, Los Angeles, CA, United States; Laura Wozniak, UCLA Pediatric Gastroenterology, Los Angeles, CA, United States; Meghan H. Pearl, UCLA Mattel Childrens Hospital, Los Angeles, CA, United States

Background: Angiotensin II type-1 receptor antibody (AT1R-Ab) has been associated with vascular injury and graft dysfunction in pediatric kidney and liver transplant recipients. A recent cohort of adult liver transplant recipients demonstrated an association between declining estimated glomerular filtration rate (eGFR) and the presence of AT1R-Ab at 1 year post-transplant. The role of AT1R-Ab in the development of chronic kidney disease in pediatric non-renal solid-organ transplant recipients has not been explored.  

Objective: To evaluate the association of AT1R-Ab with change in eGFR and development of hypertension in pediatric liver and intestinal transplant recipients.

Design/Methods: 25 pediatric intestinal transplant recipients and 78 pediatric liver transplant recipients had AT1R-Ab levels measured at one time point post-transplant. Baseline information including gender, age at time of transplant, and age at time of AT1R-Ab measurement were compared in AT1R-Ab positive and negative subjects. EGFR (using the creatinine-based CKiD U25 or CKD-EPI 2009 equation as appropriate), blood pressure classification (using the 2017 American Academy of Pediatrics guidelines), and antihypertensive medication use were determined at the time of AT1R-Ab measurement, at 1 year post-measurement, and at the most recent routine clinic visit. AT1R-Ab positivity was defined as >17 units/mL. The effect of AT1R-Ab positivity on change in eGFR was determined using a mixed-effect linear regression model.

Results: AT1R-Ab was positive in 36% of liver and 68% of intestinal transplant recipients. Younger age at time of AT1R-Ab measurement was associated with AT1R-Ab positivity in liver transplant recipients. No association between age and AT1R-Ab status was identified in the intestinal transplant cohort. There was no association between AT1R-Ab status and change in eGFR 1 year post-measurement, prevalence of hypertension, or use of antihypertensive medications (Table 1). There was no significant change in eGFR from the time of AT1R-Ab measurement to the most recent clinic visit in both the intestinal and liver transplant recipients. Additionally, there was no effect of AT1R-Ab positivity on change in eGFR during this time period (Figure 1a, 1b).Conclusion(s): Younger age may be a risk factor for AT1R-Ab positivity in pediatric liver transplant recipients.  AT1R-Ab positivity was not associated with a decline in eGFR or hypertension in pediatric liver and intestinal transplant recipients. Further studies are needed using other markers of kidney function, such as cystatin C, to validate this finding. 
Table 1Demographic information, eGFR measurements, hypertension prevalence and antihypertensive use at time of AT1R-Ab measurement, at 1 year post-measurement and at the most recent clinic visit.
Figure 1. Trend of eGFR (ml/min/1.73m2) over time.Each black line represents an individual subject’s eGFR from the time of AT1R-Ab measurement to the most recent clinic visit and blue lines represent the average trend of eGFR in the a) intestinal cohort and b) liver cohort. A mixed-effect linear regression model was used to evaluate the effect of AT1R-Ab status on change in eGFR. Overall, eGFR was stable in both cohorts and there was no association between AT1R-Ab positivity and change in eGFR (p=0.97 in the intestinal cohort and 0.55 in the liver cohort).