Understanding the immune response changes to clinical interventions for Epstein-Barr virus infection prior to lymphoma development in children after organ transplants (UNEARTH)

Abstract/Summary Among the Epstein-Barr virus associated cancers is post-transplant lymphoproliferative disease (PTLD), a rare but major complication of pediatric solid organ transplants (SOT). Many children are EBV-seronegative at time of SOT, leading to primary EBV infection from the allograft under intense immunosuppression, and a higher chance of a chronic high viral load (CHVL) state or PTLD. Longitudinal peripheral blood EBV DNA nucleic acid testing (NAT) has not improved the individual prediction of PTLD occurrence, likely due to variable SOT recipient immune responses. Further, these patients receive clinical interventions for EBV DNAemia, with incomplete responses for unknown reasons. Our team of SOT, infectious disease and immunology professionals will bring new and complimentary expertise to close these knowledge gaps. We will perform longitudinal T and NK cell immune function assays in conjunction with local and central EBV and anellovirus NAT in 1390 samples across 5 time points in the first year after 278 SOT (kidney, liver, heart, lung or intestine) at 3 major children's hospitals. We will accomplish the following Specific Aims, comparing thoracic and abdominal SOT recipients with primary EBV infection or CHVL state: 1. Assess the prospective phenotypic and functional features of T cell “exhaustion” and correlate with EBV infection outcomes and NK cell profile. Hypothesis: SOT recipients' that develop CHVL state display distinct phenotypic memory differentiation and exhausted CD8+ and CD4+ T cell profiles that are regulated by distinct inflammatory circuits. We will accomplish this aim by performing multi- spectral flow cytometry to characterize T cell phenotype and function, as well as Meso Scale Discovery platform to assess distinct viral control-relevant plasma cytokines/chemokines, during the phases of initial replication, expansion, progression, CHVL or recovery states. 2. To prospectively define the number, phenotype, and functional status of NK cells, and correlate with EBV infection outcomes. Hypothesis: NK cell activation will coincide with primary infection, and will correlate positively with clearance vs. negatively with persistent EBV replication. NK cell dysfunction will develop in patients with CHVL, who are at highest risk of PTLD. We will leverage our established multi-spectral flow cytometry panel and analyze patients with primary EBV infection after SOT and answer questions related to the activation status, NK receptor repertoire, and functional capacity. 3. Determine the association of peripheral blood torquetenovirus (TTV) DNA loads to EBV outcomes, T and NK cell profiles. Hypothesis: TTV loads reduce with clinical reductions in immunosuppression and predict EBV clearance. We will accomplish this aim using longitudinal whole blood NAT assays for both viruses at common time points, performed centrally to minimize lab variability. By study end, we will know the T and NK immune responses to EBV across multiple clinical situations. We expect to find key immune mechanisms that will predict poor or delayed EBV clearance despite clinical interventions, which may lead to new translational immunotherapy approaches to prevent PTLD, or inform EBV oncogenesis in other populations.