Variations in DNA methylation of interferon gamma and programmed death 1 in allograft rejection after kidney transplantation

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K. Boer, L.E.A. de Wit, F.S. Peters, D.A. Hesselink, L.J. Hofland, M.G.H. Betjes, C.W.N. Looman, C.C. Baan

Chair(s): Dr. E.M. van Maarseveen

Thursday 9 march 2017

12:45 - 13:00h

Categories: Poster - Basaal

Parallel session: Postersessie - Basaal 2

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The role of DNA methylation in the regulation of the anti-donor directed immune response after organ transplantation is unknown. Here, we studied the methylation of two mediators of the immune response: the pro-inflammatory cytokine interferon γ(IFNγ) and the inhibitory receptor programmed death 1 (PD1) in CD8+ T-cell subsets in kidney transplant recipients.

Using pyrosequencing, the DNA methylation of regulatory CpGs in the promoter region of either IFNγ or PD1 was determined in FACS sorted naïve (CD27+CD45RA+), CD27+ memory (CD27+CD45RA-), CD27- memory (CD27-CD45RA-) and differentiated effector memory (EMRA; CD27-CD45RA+) CD8+ T-cell subsets before and 3 and 12 months after kidney transplantation. Both kidney transplant recipients experiencing an episode of acute allograft rejection (rejectors) as well as recipients without rejection (non-rejectors) were included.

Both IFNγ and PD1 were significantly (p<0.001) higher methylated in the naïve CD8+ T cells compared to the memory T-cell subsets. The methylation status of both IFNγand PD1 inversely correlated with the % of IFNγ or PD1 producing cells. At 3 months after transplantation, irrespective of rejection and subsequent anti-rejection therapy, the IFNy methylation was significantly higher in the EMRA CD8+ T cells (p=0.01) whereas the PD1 methylation was significantly higher in all memory CD8+ T-cell subsets (CD27+ memory; p=0.02: CD27- memory; p=0.02: EMRA; p=0.002). Comparing the increase in methylation in the first 3 months after transplantation between rejectors and non-rejectors demonstrated a significantly more prominent increase in the PD1 methylation in the CD27- memory CD8+ T cells in rejectors (increase in rejectors: 14%, increase in non-rejectors: 1.9%, p=0.04). The increase in DNA methylation in the other memory CD8+ T cells was not significantly different between rejectors and non-rejectors. At 12 months after transplantation the methylation of both IFNγ and PD1 returned to pre transplantation levels.

The DNA methylation of both IFNγ and PD1 increases the first 3 months after transplantation in memory CD8+ T cells in kidney transplant recipients. This increase was present in both rejectors and non-rejectors indicating that general factors of the kidney transplantation procedure, including the use of immunosuppressive medication, contribute to these variations in DNA methylation.