Among kidney transplant donors, the CAV1 rs4730751 SNP was significantly associated with allograft failure in 2 independent cohorts.

This study was a retrospective analysis of the European Liver Transplant Registry (ELTR) performed to compare long‐term outcomes with prolonged‐release tacrolimus versus tacrolimus BD in liver transplantation (January 2008–December 2012). Clinical efficacy measures included univariate and multivariate analyses of risk factors influencing graft and patient survival at 3 years posttransplant. Efficacy measures were repeated using propensity score‐matching for baseline demographics. Patients with <1 month of follow‐up were excluded from the analyses. In total, 4367 patients (prolonged‐release tacrolimus: n = 528; BD: n = 3839) from 21 European centers were included. Tacrolimus BD treatment was significantly associated with inferior graft (risk ratio: 1.81; p = 0.001) and patient survival (risk ratio: 1.72; p = 0.004) in multivariate analyses. Similar analyses performed on the propensity score‐matched patients confirmed the significant survival advantages observed in the prolonged‐release tacrolimus‐ versus tacrolimus BD‐treated group. This large retrospective analysis from the ELTR identified significant improvements in long‐term graft and patient survival in patients treated with prolonged‐release tacrolimus versus tacrolimus BD in primary liver transplant recipients over 3 years of treatment. However, as with any retrospective registry evaluation, there are a number of limitations that should be considered when interpreting these data.

1 Endothelium-derived hyperpolarizing factor (EDHF) has recently been identi®ed as potassium released from endothelial cells into the myo-endothelial space. The present study was designed to test this hypothesis. 2 In rat small mesenteric arteries, mounted in a wire myograph, relaxation to acetylcholine or potassium was not signi®cantly changed following incubation with oxadiazolo-quinoxalin-1-one (ODQ, 4 mM) and indomethacin (10 mM, n=9). 3 Maximal relaxations to acetylcholine occurred in all arteries, were maintained and were signi®cantly greater (P50.01, n=9) than the transient relaxations to potassium, which only occurred in 30 ± 40% of vessels. 4 Removal of the vascular endothelium abolished relaxant responses both to potassium and acetylcholine (P50.005, n=9). 5 Compared with responses in 5.5 mM potassium PSS, relaxation responses to added potassium in arteries maintained in 1.5 mM potassium PSS were more marked and were not dependent on the presence of an intact endothelium (n=8). 6 Incubation with BaCl 2 (50 mM) signi®cantly inhibited the maximal relaxant response to potassium in the presence of an intact endothelium in 5.5 mM potassium PSS (P50.05, n=4), but had no eect on relaxation of de-endothelialized preparations in 1.5 mM potassium PSS (n=5). 7 Treatment with ouabain (0.1 mM) abolished the relaxant response to potassium in 1.5 mM potassium PSS (P50.001, n=9), but only partly inhibited the maximal relaxant response to acetylcholine in 5.5 mM potassium PSS (P50.01, n=5). 8 These data show that at physiological concentrations of potassium an intact endothelium is necessary for potassium-induced relaxation in rat mesenteric arteries. Furthermore, the response to potassium is clearly dierent to that from acetylcholine, indicating that potassium does not mimic EDHF released by acetylcholine in these arteries.

Late allograft dysfunction is a significant problem following liver transplantation and its pathogenesis is uncertain. HLA-C is the major inhibitory ligand for killer immunoglobulin-like receptors (KIRs) that regulate the cytotoxic activity of natural killer (NK) cells. HLA-C alleles can be allocated into two groups, termed HLA-C1 and HLA-C2, based on their KIR specificity. HLA-C2 interactions are more inhibiting to NK cell activation. We studied the clinical importance of HLA-C genotype in a large liver transplant cohort and found that possession of at least one HLA-C2 allele by the donor allograft was associated with less histological evidence of chronic rejection and graft cirrhosis, a 16.2% reduction in graft loss (p = 0.003) (hazard ratio: 2.7, 95% CI 1.4-5.3) and a 13.6% improvement in patient survival (p = 0.01) (hazard ratio: 1.9, 95% CI 1.1-3.3) at 10 years. Transplantation of an HLA-C2 homozygous allograft led to a particularly striking 26.5% reduction in graft loss (p < 0.001) (hazard ratio: 7.2, 95% CI 2.2-23.0) at 10 years when compared to HLA-C1 homozygous allografts. Donor HLA-C genotype is therefore a major determinant of clinical outcome after liver transplantation and reveals the importance of NK cells in chronic rejection and graft cirrhosis. Modulation of HLA-C and KIR interactions represents an important novel approach to promote long-term graft and patient survival.