Post-transplant lymphoproliferative disorder (PTLD) is a potentially fatal complication of organ transplantation commonly associated with Epstein Barr virus (EBV) infection. More than 90% of the world population is infected with EBV having acquired the infection either in childhood or adolescence. Primary infection during adolescence can result in infectious mononucleosis (IM), an acute but self-limiting infection. However, IM and PTLD both lead to a robust proliferation of infected lymphoblastoid B cells. EBV encodes several viral microRNAs (miRNA) and infection with EBV can significantly alter the cellular miRNA landscape of infected B cells. In this study we asked if the miRNAs associated with IM mirror the miRNA detected during PTLD.

miRNA-microarray profiling was used to quantitate expression levels of miRNA in RNA isolated from PBMC (n=14) from college students diagnosed with IM, from spontaneously arising EBV⁺ B lymphoma cell lines from patients with PTLD (n=6), and normal human B cells (n=10). One-way ANOVA analysis was used to identify the miRNAs differentially modulated within the groups. Thirty miRNAs were uniquely modulated in IM (22 up, 8 down) while sixteen miRNAs were uniquely modulated in PTLD (13 up, 3 down). Interestingly, there is no overlap between the miRNAs differentially expressed in PTLD and IM. To further examine miRNAs associated with PTLD, real-time qPCR was used and five miRNAs (17-5p, 19a, 106a, 422a and 449b) were validated as statistically significantly upregulated in PTLD. These same miRNAs were detected in RNA isolated from exosomes from the culture supernatant of EBV⁺ B lymphoma cell lines from patients with PTLD. Archival serum samples, stored >15 years, (n=11) from transplant recipients with high EBV viral loads were analyzed and elevated levels of 3 of 5 miRNAs (17-5p, 19a, 106a) were detected. Importantly, this panel of miRNAs (17-5p, 19a, 106a, 422a and 449b) were also detected in RNA isolated from formalin-fixed paraffin-embedded tissue sections from these PTLD tumors.

Our findings clearly demonstrate that the miRNA profile of EBV+ acute IM is distinct from the miRNome observed during EBV+ PTLD. Moreover, analysis of EBV+ tumors, serum, and cell-free exosomes have identified a panel of miRNA that have great potential as biomarkers of PTLD.

CITATION INFORMATION: Balachandran Y, Kaul V, Maloney E, Harris-Arnold A, Weinberg K, Boyd S, Bernstein D, Esquivel C, Martinez O, Krams S. The miRNome of EBV+ PTLD is Distinct from EBV+ Infectious Mononucleosis. Am J Transplant. 2017;17 (suppl 3).

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