Importance of vascular calcification in kidney transplant recipients.

BACKGROUND: Kidney transplantation is the treatment of choice for chronic kidney disease (CKD), but in kidney transplant recipients (KTRs) cardiovascular events are the first cause of death with a functioning graft, ranging from 36 to 55%. The impact of vascular calcification (VC) on morbidity and mortality of KTRs is not appreciated enough nowadays. SUMMARY: This review summarizes 13 important studies on VC in KTRs, comparing the results with CKD and dialysis populations. We focused on VC evaluation and use of coronary artery calcification (CAC) and aorta calcification (AoC) scores. We also evaluated the influence of traditional and non-traditional progression risk factors. KEY MESSAGES: VC strongly predicts cardiovascular events and all-cause mortality in KTRs. VC assessment is important in KTRs and based essentially on multislice computed tomography or electron beam computed tomography recognition of lesions. Quantitative measurement of CAC and AoC scores is essential for a correct definition of the calcium burden before and after kidney transplant. Progression of CAC slows down but does not halt after kidney transplant. A variable association of both traditional and non-traditional risk factors is shown. There is a strong association between baseline CAC score and CAC progression. A significant improvement in secondary hyperparathyroidism after transplantation favorably affects the progression of CAC. Low 25(OH)D3 levels are an independent determinant of CAC progression. Diabetes is a risk factor for the presence of CAC in KTRs, but has not been independently associated with CAC progression. The data published on the use of immunosuppressive drugs as progression factors are few and inconclusive.

The impact of apoptosis and inflammation gene polymorphisms on transplanted kidney function.

BACKGROUND: The progressive deterioration of kidney allograft function leads in most cases to transplant failure. Polymorphisms in genes encoding for inflammatory and apoptosis molecules may be one possible explanation for interindividual differences in kidney transplant outcomes. The objective of our work was to identify the possible effect of interleukin 6 (IL-6), transforming growth factor beta 1 (TGFB1), and Fas on graft function. MATERIAL AND METHODS: A case-control study was carried out to assess potential associations between polymorphisms in inflammation- and apoptosis-related genes and the risk for chronic impairment of kidney graft function. The study included 376 cadaveric kidney recipients, 256 of them with stable graft function and 120 who experienced renal deterioration during the follow-up period of 2.6 ± 1.4 years. Genotyping of IL-6/G-174C, TGFB1/L10P, TGFB1/R25P, and Fas/G-670A polymorphisms was performed by PCR-RFLP and direct sequencing. RESULTS: Considering the single IL-6, TGFB1, and Fas polymorphisms, we found similar allelic and genotype frequencies between the 2 groups. To test the hypothesis of mutual effects of polymorphisms, multiple logistic regression was performed incorporating data for all the possible dual genotypic associations. The association of IL-6 high producer and Fas low producer genotype resulted in a protective effect against graft dysfunction (OR=0.79; 95% C.I.=0.72-0.86). CONCLUSIONS: This study did not find significant associations of apoptosis and inflammation gene polymorphisms with transplanted kidney function in Italian renal transplant recipients. However, our data seem to indicate that the carriage of IL-6 high producer/Fas low producer genotype has a protective effect against graft function loss.

Prediction of three-year outcome of renal transplantation from optimal donors versus expanded criteria donors.

BACKGROUND/AIMS: The shortage in organ supply has required the use of expanded criteria donors (ECD) for kidney transplantation. Current pre-transplant evaluations of ECD organs are based on histological, clinical or mixed criteria. This monocentric study investigates the predictivity of Karpinski's histological score on 3-year graft function in renal transplant. Ex-post classification using Nyberg's score was carried out to assess the reliability of a purely clinical score and its applicability for organ allocation. METHODS: We evaluated 407 deceased donors (251 optimal and 156 ECD) for renal transplants performed between 2001 and 2006. The differences in creatinine levels and MDRD-GFR at transplant and 1, 2 and 3 years post-transplant between optimal donors and ECD were recorded. Amongst ECD organs, the effect of different Karpinski score classes (0-1, 2, 3, 4, double transplants) on 3-year graft outcomes was analyzed. We then compared renal function over time across the Nyberg grades (A, B, C, and D). RESULTS: Karpinski scores 0-1 and 2 and double transplants were associated with improved graft function compared to scores 3 and 4. Nyberg's clinical score shows a good fit with medium-term outcome and Karpinski's score, but among the donors with a high Nyberg grade (C and D), it fails to differentiate between allocable or non-allocable organs (due to Karpinski's score ≥7). CONCLUSIONS: Our data demonstrate a correlation of histological damage at the time of transplant with 3-year graft function, but at present we are unable to provide any supposition on the possible outcome of the discarded kidneys.

Cardiovascular disease in kidney transplant recipients: the prognostic value of inflammatory cytokine genotypes.

BACKGROUND: Cardiovascular disease (CVD) represents the main cause of morbidity and mortality after renal transplantation. In view of the modern paradigm of atherosclerosis as an inflammatory disease, this study investigated the impact of inflammatory cytokine polymorphisms on posttransplant CVD. METHODS: The association between cytokine polymorphisms and CVD was assessed in a case-control study to identify the differences in genotype distributions between kidney allografts with or without posttransplant CVD. To validate our results in two independent groups, we divided a cohort of 798 renal transplant recipients according to geographic area: an evaluation cohort of 478 patients from Emilia-Romagna and a validation cohort of 320 patients from the rest of Italy. Tumor necrosis factor (TNF)-alpha, transforming growth factor-beta1, interleukin (IL)-10, IL-6, interferon-gamma, and IL-8 polymorphisms were analyzed, and thereafter, the cytokine production genotype was assigned. RESULTS: In the evaluation cohort, the patients in the CVD and no-CVD groups differed significantly in TNF-alpha and IL-10 genotype frequencies. Using multivariate analyses to test the association with CVD, the TNF-alpha high-producer genotype was associated with a significantly increased cardiovascular risk (odds ratio [OR]=4.41, 95% confidence interval (CI)=2.53-7.67). Conversely, the IL-10 high-producer genotype resulted protective against CVD (OR=0.07, 95% CI=0.02-0.29). These findings were confirmed in the validation cohort where the carriers of the TNF-alpha high-producer genotype proved to be at 2.45-fold increased cardiovascular risk (OR=2.45, 95% CI=1.29-4.63), whereas the IL-10 high-producer genotype was associated with a 0.08-fold reduced risk (OR=0.08, 95% CI=0.02-0.36). CONCLUSIONS: This work suggests a prognostic value of TNF-alpha and IL-10 genotypes, which might represent cardiovascular risk markers in renal transplant.

Chronic allograft nephropathy--a clinical syndrome: early detection and the potential role of proliferation signal inhibitors.

Chronic allograft nephropathy (CAN) leads to the majority of late graft loss following renal transplantation. Detection of CAN is often too late to permit early intervention and successful management. Most current strategies for managing CAN rely on minimizing or eliminating calcineurin inhibitors (CNIs) once CAN has become established. The proliferation signal inhibitors everolimus and sirolimus have potent immunosuppressive and antiproliferative actions, with the potential to alter the natural history of CAN by reducing CNI exposure whilst avoiding acute rejection. Whilst data will be forthcoming from a number of clinical trials investigating this potential, we discuss early detection of CAN and the rationale for a role for this class of agent.