Prevention of cytomegalovirus (CMV) is essential in organ transplantation. The two main strategies are pre-emptive therapy, in which one screens for and treats asymptomatic CMV viremia, and universal antiviral prophylaxis. We compared these strategies and examined long-term outcomes in a randomized, open-label, single-center trial. We randomly assigned 70 renal transplant recipients (CMV-seropositive recipient or donor) to 3-month prophylaxis with valacyclovir (n=34) or pre-emptive valganciclovir for significant CMV viremia detected at predefined assessments through month 12 (n=36). Among the 55 patients who had a protocol biopsy specimen available at 3 years to allow assessment of the primary outcome, 9 (38%) of 24 patients in the prophylaxis group and 6 (19%) of 31 patients in the pre-emptive therapy group had moderate to severe interstitial fibrosis and tubular atrophy (odds ratio, 2.50; 95% confidence interval, 0.74-8.43; P=0.22). The prophylaxis group had significantly higher intrarenal mRNA expression of genes involved in fibrogenesis. The occurrence of CMV disease was similar in both groups, but pre-emptive therapy improved 4-year graft survival (92% versus 74%; P=0.049) as a result of worse outcomes in patients with late-onset CMV viremia. In conclusion, compared with valacyclovir prophylaxis, pre-emptive valganciclovir therapy may lead to less severe interstitial fibrosis and tubular atrophy and to significantly better graft survival.

These observations suggest an association of B-cell signatures, seen also in drug-free tolerant patients, with controlled alloimmune response.

ABCB1 haplotypes modify the risk of acute rejection, suggesting that ABCB1 allelic arrangement is a stronger regulator of P-glycoprotein activity than single polymorphisms. The risk of acute rejection determined by ABCB1 is independent of pharmacokinetic parameters. CYP3A haplotypes control the bioavailability of Tac, but do not modify the risk of acute rejection.

The activating cytotoxicity receptor NKG2D binds to stress-regulated molecules encoded by the major histocompatibility complex class I chain-related (MIC) and UL-16-binding protein (ULBP)/retinoic acid early transcript (RAET) gene family. To assess whether acute allograft rejection leads to an induction of these inducible ligands and their receptor NKG2D, we examined the mRNA profiles in kidney transplant biopsies. Expression levels were correlated with the incidence of acute rejection (aRx) episodes and chronic allograft nephropathy (CAN) proven by histology. Whereas MICA, ULBP1/3 and RAET1-E did not display heightened gene expression, elevated levels of NKG2D mRNA could be associated with aRx (p < 0.001). Immunohistology of kidney biopsies diagnosed with aRx revealed NKG2D + cells in tubulointerstitial areas positive for CD8 + cells. Most importantly, elevated levels of NKG2D mRNA were associated with restricted long-term graft function assessed by the glomerular filtration rate at 6, 12 and 18 months posttransplantation. Induced NKG2D mRNA expression was still observable in biopsies diagnosed with CAN (p < 0.001), demonstrating a higher sensitivity and specificity compared to CD3, granzyme B and granulysin mRNA measurement. Significant elevated levels of NKG2D mRNA M. Seiler and I. Brabcova contributed equally to the manuscript. could be further detected in urine sediment prior to aRx, suggesting this receptor as a new candidate marker for the diagnosis of acute and chronic allograft rejection.

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