Plasma Induced Transcriptional Analysis Assessment of Rejection in Pediatric Heart Transplantation

Abstract

Graft rejection after heart transplantation (HT) is a key clinical issue. The diagnostic gold standard of cardiac catheterization with myocardial biopsies is an invasive procedure that may underdiagnose rejection. A possible novel noninvasive alternative is using plasma to perform transcriptional analysis (TA) to assess gene expression levels associated with rejection. Studies on TA in pediatric HT are lacking. This study aimed to investigate plasma induced TA as an assessment of acute cellular rejection (ACR) in pediatric HT. Plasma collected from 25 pediatric HT recipients at the time of catheterization was used to induce a transcriptional response, measured by Affymetrix U133+2.0 array, in commercially available peripheral blood mononuclear cells. Additional data collected included age, gender, time since transplant (TST), cardiac index (CI), right ventricular end diastolic pressure (RVEDP), wedge pressure (WP), echo ejection fraction (EF), and NT Pro BNP. Subjects with ACR (defined as grade ≥ 1R on biopsy) were compared to those with no rejection (NR). 10 patients had ACR and 15 had NR. There were no significant differences between ACR and NR in age (8.5 vs 9.3 years, p=0.76), gender (60% vs 53% male, p=0.74), TST (3.4 vs 3.7 years, p=0.75), CI (3.8 vs 3.2 L/min/m2, p=0.08), RVEDP (7.8 vs 7.3 mmHg, p=0.77), WP (11.6 vs 10.5 mmHg, p=0.39), EF (65% vs 66%, p=0.49), and NT Pro BNP (831 vs 1083 pg/mL, p=0.67), respectively. Between ACR and NR, TA revealed 494 unique probesets with a false discovery rate of ≤10% (Figure 1). Genes associated with T-cell activation and migration were upregulated in the ACR group. These included CX3CR1, TNFRSF13C, TNFAIP8, ITGA4, TRDC, IL6ST, IL23A, and CD84. TA produced signatures specific to ACR in pediatric HT recipients. The identified genes were consistent with current understanding of ACR. TA can shed insight into the mechanisms of rejection in pediatric HT recipients and should be investigated further as a noninvasive diagnostic tool.