Skewed T cell responses to Epstein-Barr virus in long-term asymptomatic kidney transplant recipients

Abstract

Kidney transplant recipients (KTRs) abnormally replicate the Epstein Barr Virus (EBV). To better understand how long-term immunosuppression impacts the immune control of this EBV re-emergence, we systematically compared 10 clinically stable KTRs to 30 healthy controls (HCs). The EBV-specific T cell responses were determined in both groups by multiparameter flow cytometry with intra cellular cytokine staining (KTRs n = 10; HCs n = 15) and ELISpot-IFNγ assays (KTRs n = 7; HCs n = 7). The T/B/NK cell counts (KTRs n = 10; HCs n = 30) and the NK/T cell differentiation and activation phenotypes (KTRs n = 10; HCs n = 15/30) were also measured. We show that in KTRs, the Th1 effector CD4+ T cell responses against latent EBV proteins are weak (2/7 responders). Conversely, the frequencies total EBV-specific CD8+T cells are conserved in KTRs (n = 10) and span a wider range of EBNA-3A peptides (5/7responders) than in HCs (5/7responders). Those modifications of the EBV-specific T cell response were associated with a profound CD4+ T cell lymphopenia in KTRs compared to HCs, involving the naïve CD4+ T cell subset, and a persistent activation of highly-differentiated senescent CD8+ T cells. The proportion of total NK / CD8+ T cells expressing PD-1 was also increased in KTRs. Noteworthy, PD-1 expression on CD8+ T cells normalized with time after transplantation. In conclusion, we show modifications of the EBV-specific cellular immunity in long term transplant recipients. This may be the result of both persistent EBV antigenic stimulation and profound immunosuppression induced by anti-rejection treatments. These findings provide new insights into the immunopathology of EBV infection after renal transplantation.

Distinct immunopathological mechanisms of EBV-positive and EBV-negative posttransplant lymphoproliferative disorders

“…Included patients were classified as EBV‐pos ( n = 56) or EBV‐neg ( n = 39) according to EBV status of the tumor (Figure 1). PTLD‐free transplanted controls (TC, n = 21) were prospectively recruited from the renal ( n = 10) 14 and hepatic ( n = 5) transplantation services of the Pitié‐Salpêtrière Hospital (Paris, France) or retrospectively included ( n = 5 liver and 1 kidney) from the K‐GREF cohort 24,25 (Supplemental Methods and Figure S1).…”

“…Another hypothesis is that a low diversity of EBV‐specific T cell responses might contribute to EBV‐positive PLTLD development. We recently showed that kidney transplant recipients carrying long‐term stable EBV loads have a broader T cell recognition of the latency III‐protein EBNA‐3A than healthy individuals; a repertoire that might protect them against EBV‐posttransplant complications, 14 mainly associated with type III latency 15‐17 . One last hypothesis involves the role of EBV‐specific CD4 + T cell responses, that have shown to be low in transplant recipients with 8,18 and without 14 EBV‐positive PTLD.…”

“…We recently showed that kidney transplant recipients carrying long‐term stable EBV loads have a broader T cell recognition of the latency III‐protein EBNA‐3A than healthy individuals; a repertoire that might protect them against EBV‐posttransplant complications, 14 mainly associated with type III latency 15‐17 . One last hypothesis involves the role of EBV‐specific CD4 + T cell responses, that have shown to be low in transplant recipients with 8,18 and without 14 EBV‐positive PTLD. Moreover, EBV‐positive PTLD patients show better clinical responses when infused with CD4 + enriched EBV‐cytotoxic T cell lines (EBV‐CTL) 19 …”

Natural Killer Cells in Post-Transplant Lymphoproliferative Disorders

“…Another alteration of the NK cell phenotype at EBV-positive PTLD diagnosis, which often appears alongside one or several of the previously mentioned alterations, is the expression of the PD-1 receptor [ 32 , 34 ]. PD-1 expression by NK cells is rare in healthy individuals [ 46 ], but is often observed in association with gamma-herpesvirus infection in kidney transplant recipients with chronic EBV reactivation [ 47 ], in pediatric thoracic recipients with high EBV loads [ 34 ], and in human-herpesvirus-8 (HHV-8)-related Kaposi sarcoma patients [ 44 ]. PD-1 expression by NK cells is also frequently observed in the context of cancers in which the PD-1 ligands PD-L1/L2 are highly expressed by tumor cells [ 48 , 49 ], which is frequently the case for EBV-positive PTLDs [ 50 , 51 ].…”

“…Given the impaired state of the immune system under immunosuppressive therapy, such complementary roles become essential to maintain the delicate balance between immunity and virus/tumor development. The increased capacity of NK cells to produce IFN-γ at EBV-positive PTLD diagnosis might partially compensate for the low levels of latent EBV-specific CD4 + Th1 cells frequently observed after transplantation [ 47 , 55 , 56 ]. Thus, concomitant reduction of Th1 and NK cells limits two subsets specialized in producing high levels of the anti-viral cytokines IFN-γ and TNF-α.…”