Deciphering transplant outcomes of expanded kidney allografts donated after controlled circulatory death in the current transplant era. A call for caution.

Outcomes of kidney transplantation (KT) after controlled circulatory death (cDCD) with highly expanded criteria donors (ECD) and recipients have not been thoroughly evaluated. We analyzed in a multicenter cohort of 1161 consecutive KT, granular baseline donor and recipient factors predicting transplant outcomes, selected by bootstrapping and Cox proportional hazards, and were validated in a contemporaneous European KT cohort (n = 1585). 74.3% were DBD and 25.7% cDCD-KT. ECD-KT showed the poorest graft survival rates, irrespective of cDCD or DBD (log-rank < 0.001). Besides standard ECD classification, dialysis vintage, older age, and previous cardiovascular recipient events together with low class-II-HLA match, long cold ischemia time and combining a diabetic donor with a cDCD predicted graft loss (C-Index 0.715, 95% CI 0.675-0.755). External validation showed good prediction accuracy (C-Index 0.697, 95%CI 0.643-0.741). Recipient older age, male gender, dialysis vintage, previous cardiovascular events, and receiving a cDCD independently predicted patient death. Benefit/risk assessment of undergoing KT was compared with concurrent waitlisted candidates, and despite the fact that undergoing KT outperformed remaining waitlisted, remarkably high mortality rates were predicted if KT was undertaken under the worst risk-prediction model. Strategies to increase the donor pool, including cDCD transplants with highly expanded donor and recipient candidates, should be performed with caution.

Urinary miR-155-5p and CXCL10 as prognostic and predictive biomarkers of rejection, graft outcome and treatment response in kidney transplantation.

AIMS: MicroRNAs (miRNAs) may be useful biomarkers of rejection and allograft outcome in kidney transplantation. Elevated urinary CXCL10 levels have been associated with acute rejection (AR) and may predict allograft failure. We examined the correlation of miRNA, CXCL10 levels and immunosuppressive drug exposure with AR and graft function in kidney transplant recipients. METHODS: Eighty de novo kidney transplant recipients were recruited from four European centres. All patients received tacrolimus, mycophenolate mofetil, and methylprednisolone. Urinary pellet expression of miR-142-3p, miR-210-3p and miR-155-5p was assessed by quantitative real-time polymerase chain reaction and urinary CXCL10 levels by enzyme-linked immunosorbent assay at the 1st week and the 1st , 2nd , 3rd and 6th months post-transplantation. RESULTS: Eight patients experienced AR. Before and during AR, patients showed a significant increase of urinary miR-142-3p, miR-155-5p and CXCL10 levels and a decrease of miR-210-3p levels. Receiver operating characteristic curve analysis showed that miR-155-5p (area under the curve = 0.875; P = 0.046) and CXCL10 (area under the curve = 0.865; P = 0.029) had excellent capacity to discriminate between rejectors and nonrejectors. The optimal cut-off values for the prognosis of AR were 0.51, with 85% sensitivity and 86% specificity for miR-155-5p and 84.73 pg ml-1 , with 84% sensitivity and 80% specificity for CXCL10. miR-155-5p and CXCL10 levels correlated with glomerular filtration rate. Levels of both biomarkers normalized after recovery of graft function. CONCLUSIONS: The regular early post-transplantation monitoring of urinary miR-155-5p and CXCL10 can help in the prognosis of AR and graft dysfunction. Large prospective randomized multicentre trials are warranted to refine our cut-off values and validate the clinical usefulness of these biomarkers.

Three cases of monoclonal gammopathy of renal significance after kidney transplantation. De novo C3 glomerulopathy. / Tres casos de gammapatía monoclonal de significado renal postrasplante renal: nefropatía c3 de novo.

Monoclonal gammopathy of renal significance includes all renal disorders caused by a monoclonal immunoglobulin secreted by a non-malignant B-cell clone. Patients with MGRS do not, by definition, meet criteria for multiple myeloma, with haematological disorders generally considered to be monoclonal gammopathy of undetermined significance. Nevertheless, the renal involvement can be serious and require specific treatment. Monoclonal gammopathy of renal significance is associated with a wide spectrum of disorders, including the recently discovered C3 glomerulopathy. Development of C3 glomerulopathy in the context of monoclonal gammopathy of renal significance after kidney transplantation is uncommon and very few cases have been published to date. We report on three cases of C3 glomerulopathy in the context of de novo monoclonal gammopathy after kidney transplantation.

Medium-Term Renal Function in a Large Cohort of Stable Kidney Transplant Recipients Converted From Twice-Daily to Once-Daily Tacrolimus.

BACKGROUND: There is some evidence pointing toward better renal function in kidney transplant recipients (KTR) treated with once-daily tacrolimus (QD-TAC) vs. twice-daily tacrolimus (BID-TAC). METHODS: This is an extension study of a 1-year, single arm prospective study of stable KTR who were converted from BID-TAC to QD-TAC (4.9 ± 4.0 years after transplantation) in Spanish routine clinical practice. Patient and graft survival, renal function, acute rejection episodes, and other analytic parameters were assessed at 24 and 36 months after conversion. RESULTS: A total of 1798 KTR were included in the extension study. Tacrolimus doses at 36 months were significantly lower compared to those at time of conversion (-0.2 mg/day; P = 0.023). Blood levels were lower than baseline during all the study (P < 0.001). Graft and patient survival at 3 years after conversion were 93.9% and 95.1%, respectively. Compared with baseline, the mean estimated glomerular filtration rate (eGFR) remained very stable at all timepoints (56.7 ± 19.8 vs 58.1 ± 24.6 mL/min per 1.73 m(2) at month 36; P = 0.623). Even when patients reinitiating dialysis were counted as eGFR = 0, the mean eGFR was very stable. In fact, a small but significant increase was observed at 36 months versus baseline (+0.1 mL/min per 1.73 m(2); P = 0.025). An increase in proteinuria was observed at 36 months versus baseline (+0.11 g/24 h; P < 0.001). Acute rejection rates were low during the study. CONCLUSIONS: Conversion from BID-TAC to QD-TAC in a large cohort of stable KTR was safe and associated with a very stable renal function after 3 years. Comparative studies are warranted to assess the feasibility of such conversion.

KAP degradation by calpain is associated with CK2 phosphorylation and provides a novel mechanism for cyclosporine A-induced proximal tubule injury.

The use of cyclosporine A (CsA) is limited by its severe nephrotoxicity that includes reversible vasoconstrictor effects and proximal tubule cell injury, the latter associated whith chronic kidney disease progression. The mechanisms of CsA-induced tubular injury, mainly on the S3 segment, have not been completely elucidated. Kidney androgen-regulated protein (KAP) is exclusively expressed in kidney proximal tubule cells, interacts with the CsA-binding protein cyclophilin B and its expression diminishes in kidneys of CsA-treated mice. Since we reported that KAP protects against CsA toxicity in cultured proximal tubule cells, we hypothesized that low KAP levels found in kidneys of CsA-treated mice might correlate with proximal tubule cell injury. To test this hypothesis, we used KAP Tg mice developed in our laboratory and showed that these mice are more resistant to CsA-induced tubular injury than control littermates. Furthermore, we found that calpain, which was activated by CsA in cell cultures and kidney, is involved in KAP degradation and observed that phosphorylation of serine and threonine residues found in KAP PEST sequences by protein kinase CK2 enhances KAP degradation by calpain. Moreover, we also observed that CK2 inhibition protected against CsA-induced cytotoxicity. These findings point to a novel mechanism for CsA-induced kidney toxicity that might be useful in developing therapeutic strategies aimed at preventing tubular cell damage while maintaining the immunosuppressive effects of CsA.

Increased oxidative stress, the renin-angiotensin system, and sympathetic overactivation induce hypertension in kidney androgen-regulated protein transgenic mice.

Gender differences in the incidence and severity of hypertension have suggested the involvement of a sex-dependent mechanism. Transgenic (Tg) mice overexpressing kidney androgen-regulated protein (KAP) specifically in kidney showed hypertension associated with oxidative stress. Reactive oxygen species (ROS) are strongly implicated in the pathological signaling leading to hypertension in a framework that includes renin-angiotensin system (RAS) activation, increased sympathetic activity, and cardiac remodeling. In this report, we observed that plasma levels of angiotensin II and catecholamines were increased in KAP Tg mice, compared with wild-type animals. Systemic administration of Tempol, a membrane-permeative superoxide dismutase mimetic, reduced arterial pressure as well as urinary excretion of oxidative stress markers and reduced both angiotensin II and norepinephrine plasma levels in KAP Tg mice. Intracerebroventricular administration of Tempol also reduced arterial pressure in Tg mice. Moreover, administration of apocynin and DPI, inhibitors of NADPH oxidase, a major source of ROS, also reduced arterial pressure and both angiotensin II and norepinephrine plasma levels in Tg mice. Thus, we analyzed the involvement of the RAS and sympathetic nervous system in KAP Tg mouse hypertension. Both captopril and losartan reduced arterial blood pressure in Tg mice, as also occurred after ß-adrenergic blockade with atenolol. Also, intracerebroventricular losartan administration reduced arterial pressure in KAP Tg mice. Our data demonstrate that hypertension in male KAP Tg mice is based on increased oxidative stress, increased sympathetic activity, and RAS activation. Moreover, our results suggest a role for increased oxidative stress in the CNS as a major cause of hypertension in these animals.