Anuria after kidney transplantation diagnosed as early recurrence of focal segmental glomerulosclerosis combined with acute calcineurin inhibitor nephrotoxicity: a case report and literature review.

BACKGROUND: Primary focal segmental glomerulosclerosis (FSGS) is a glomerular disease that sometimes recurs in patients after kidney transplantation (KT) and increases the risk of graft loss. Proteinuria is a common early sign of recurrent FSGS, but an abrupt decrease in urine volume is rare. Herein, we report a patient with early recurrence of FSGS with anuria following KT. CASE PRESENTATION: A 55-year-old man with end-stage kidney disease caused by primary FSGS experienced anuria on postoperative day 2 following deceased donor KT. Laboratory results revealed that serum tacrolimus trough levels were consistently elevated at the time of anuria. At first, we considered acute calcineurin inhibitor (CNI) nephrotoxicity based on graft biopsy on light microscopy, laboratory findings, and clinical courses. However, the allograft function did not recover even after discontinuation of CNI, and recurrent FSGS was diagnosed 2 weeks later on electron microscopy. A total of 13 sessions of plasmapheresis and two administrations of rituximab (375 mg/m2) were required to treat recurrent FSGS. The patient achieved a partial response, and the spot urine protein-to-creatinine ratio decreased from 15.5 g/g creatinine to 5.2 g/g creatinine. At 5 months following KT, the serum creatinine level was stable at 1.15 mg/dL. CONCLUSIONS: These findings highlight that anuria can occur in cases of early recurrence of FSGS combined with acute CNI nephrotoxicity.

Impact of the ACE2 activator xanthenone on tacrolimus nephrotoxicity: Modulation of uric acid/ERK/p38 MAPK and Nrf2/SOD3/GCLC signaling pathways.

AIMS: The calcineurin inhibitor tacrolimus is an effective and widely used immunosuppressant after organ transplantation to reduce graft rejection. However, its nephrotoxic effect could compel the patients to treatment discontinuation. The beneficial effects of angiotensin-converting enzyme 2 (ACE2) on the kidney and other organs have been investigated in several studies, but its role in tacrolimus nephrotoxicity still needs to be elucidated. Our study was designed to investigate effects of the ACE2 activator xanthenone on tacrolimus-induced renal injury. MATERIALS AND METHODS: Male Wistar rats were administered xanthenone (2 mg/kg) concurrently with tacrolimus (1 mg/kg) for 3 weeks, then blood and kidney tissue samples were collected for biochemical and molecular investigations. KEY FINDINGS: Co-administration of xanthenone significantly improved renal functions in tacrolimus-treated rats, where serum creatinine, urea, and uric acid levels were close to those of the normal control. Besides, xanthenone reduced renal angiotensin (ANG) II content, while elevated ANG (1-7). Relative protein expressions of p-ERK/ERK and p-p38 MAPK/p38 MAPK inflammatory signals were downregulated upon xanthenone administration with tacrolimus. In addition, xanthenone reinforced antioxidant defense against tacrolimus by enhancing protein expression of the transcription factor Nrf2 with subsequently increased mRNA expressions of the antioxidants SOD3 and GCLC. SIGNIFICANCE: These protective effects of xanthenone could be attributed to ANG II degradation to ANG (1-7) by ACE2 activation resulting in regulated inflammatory and oxidative responses in the kidney. Therefore, administration of xanthenone along with tacrolimus could be a promising therapeutic strategy to reduce the adverse effects and increase the tolerability to tacrolimus immunosuppressive therapy.

An Integrated Transcriptomic Approach to Identify Molecular Markers of Calcineurin Inhibitor Nephrotoxicity in Pediatric Kidney Transplant Recipients.

Calcineurin inhibitors are highly efficacious immunosuppressive agents used in pediatric kidney transplantation. However, calcineurin inhibitor nephrotoxicity (CNIT) has been associated with the development of chronic renal allograft dysfunction and decreased graft survival. This study evaluated 37 formalin-fixed paraffin-embedded biopsies from pediatric kidney transplant recipients using gene expression profiling. Normal allograft samples (n = 12) served as negative controls and were compared to biopsies exhibiting CNIT (n = 11). The remaining samples served as positive controls to validate CNIT marker specificity and were characterized by other common causes of graft failure such as acute rejection (n = 7) and interstitial fibrosis/tubular atrophy (n = 7). MiRNA profiles served as the platform for data integration. Oxidative phosphorylation and mitochondrial dysfunction were the top molecular pathways associated with overexpressed genes in CNIT samples. Decreased ATP synthesis was identified as a significant biological function in CNIT, while key toxicology pathways included NRF2-mediated oxidative stress response and increased permeability transition of mitochondria. An integrative analysis demonstrated a panel of 13 significant miRNAs and their 33 CNIT-specific gene targets involved with mitochondrial activity and function. We also identified a candidate panel of miRNAs/genes, which may serve as future molecular markers for CNIT diagnosis as well as potential therapeutic targets.

Calcineurin A-α suppression drives nuclear factor-κB-mediated NADPH oxidase-2 upregulation.

Calcineurin inhibitors (CNIs) are vital immunosuppressive therapies in the management of inflammatory conditions. A long-term consequence is nephrotoxicity. In the kidneys, the primary, catalytic calcineurin (CnA) isoforms are CnAα and CnAß. Although the renal phenotype of CnAα-/- mice substantially mirrors CNI-induced nephrotoxicity, the mechanisms downstream of CnAα are poorly understood. Since NADPH oxidase-2 (Nox2)-derived oxidative damage has been implicated in CNI-induced nephrotoxicity, we hypothesized that CnAα inhibition drives Nox2 upregulation and promotes oxidative stress. To test the hypothesis, Nox2 regulation was investigated in kidneys from CnAα-/-, CnAß-/-, and wild-type (WT) littermate mice. To identify the downstream mediator of CnAα, nuclear factor of activated T cells (NFAT) and NF-κB regulation was examined. To test if Nox2 is transcriptionally regulated via a NF-κB pathway, CnAα-/- and WT renal fibroblasts were treated with the NF-κB inhibitor caffeic acid phenethyl ester. Our findings showed that cyclosporine A treatment induced Nox2 upregulation and oxidative stress. Furthermore, Nox2 upregulation and elevated ROS generation occurred only in CnAα-/- mice. In these mice, NF-κB but not NFAT activity was increased. In CnAα-/- renal fibroblasts, NF-κB inhibition prevented Nox2 upregulation and reactive oxygen species (ROS) generation. In conclusion, these findings indicate that 1) CnAα loss stimulates Nox2 upregulation, 2) NF-κB is a novel CnAα-regulated transcription factor, and 3) NF-κB mediates CnAα-induced Nox2 and ROS regulation. Our results demonstrate that CnAα plays a key role in Nox2 and ROS generation. Furthermore, these novel findings provide evidence of divergent CnA isoform signaling pathways. Finally, this study advocates for CnAα-sparing CNIs, ultimately circumventing the CNI nephrotoxicity.NEW & NOTEWORTHY A long-term consequence of calcineurin inhibitors (CNIs) is oxidative damage and nephrotoxicity. This study indicates that NF-κB is a novel calcineurin-regulated transcription factor that is activated with calcineurin inhibition, thereby driving oxidative damage in CNI nephropathy. These findings provide additional evidence of divergent calcineurin signaling pathways and suggest that selective CNIs could improve the long-term outcomes of patients by mitigating renal side effects.

Glomerular Neovascularization in Nondiabetic Renal Allograft Is Associated with Calcineurin Inhibitor Toxicity.

INTRODUCTION: Extra efferent arterioles, also known as polar vasculosis (PV), are often observed in the glomerular vascular pole and are associated with glomerular hypertrophy, indicating early recurrent diabetic kidney disease (DKD) in renal allografts. However, its significance in patients without diabetes remains uncertain. METHODS: A total of 9,004 renal allograft biopsy specimens obtained between January 2007 and December 2017 at Tokyo Women's Medical University were retrospectively analyzed to examine the clinical and pathological significance of PV in renal allografts. PV was identified in 186 biopsy specimens obtained from 165 patients. The PV group comprised 46 patients; 35 patients without DKD and 11 patients with DKD as the initial cause of ESRD, whose clinical information was available and treated with the calcineurin inhibitor (CNI) tacrolimus. The non-PV group comprising patients with renal allografts matched for age and postoperative day included 93 patients without DKD and 16 patients with DKD as the initial cause of ESRD. RESULTS: In patients with nondiabetic renal allografts, systolic blood pressure was significantly higher in the PV group than in the non-PV group. The trough tacrolimus levels during the overall study period and at 2 weeks, 1 month, and 2 years after transplantation were significantly higher in the PV group compared with the non-PV group. Glomerulomegaly was significantly more common. Moreover, ah and aah scores in Banff score were significantly higher in the PV group than in the non-PV group. In those with diabetic renal allografts, although the clinical parameters and tacrolimus trough levels in all time periods were not significantly different between the PV and non-PV groups, the ah score was significantly higher in the PV group. CONCLUSION: PV was associated with CNI toxicity in nondiabetic but not in diabetic renal allografts. The pathogenesis of PV in renal allografts is considered to be multifactorial.

Etiological analysis of graft dysfunction following living kidney transplantation: a report of 366 biopsies.

AIM: The aim of this study is to investigate the clinical features of graft dysfunction following living kidney transplantation and to assess its causes. METHODS: We retrospectively analyzed a series of 366 living kidney transplantation indication biopsies with a clear etiology and diagnosis from July 2003 to June 2016 at our center. The classifications and diagnoses were performed based on clinical and pathological characteristics. All biopsies were evaluated according to the Banff 2007 schema. RESULTS: Acute rejection (AR) occurred in 85 cases (22.0%), chronic rejection (CR) in 62 cases (16.1%), borderline rejection (BR) in 12 cases (3.1%), calcineurin inhibitor (CNI) toxicity damage in 41 cases (10.6%), BK virus-associated nephropathy (BKVAN) in 43 cases (11.1%), de novo or recurrent renal diseases in 134 cases (34.7%), and other causes in nine cases (2.3%); additionally, 20 cases had two simultaneous causes. The 80 cases with IgA nephropathy (IgAN) had the highest incidence (59.7%) of de novo or recurrent renal diseases. After a mean ± SD follow up of 3.7 ± 2.3 years, the 5-year graft cumulative survival rates of AR, CR, CNI toxicity, BKVAN, and de novo or recurrent renal diseases were 60.1%, 31.2%, 66.6%, 66.9%, and 67.1%, respectively. CONCLUSIONS: A biopsy is helpful for the diagnosis of graft dysfunction. De novo or recurrent renal disease, represented by IgAN, is a major cause of graft dysfunction following living kidney transplantation.

Defining a microRNA-mRNA interaction map for calcineurin inhibitor induced nephrotoxicity.

Calcineurin inhibitors induce nephrotoxicity through poorly understood mechanisms thereby limiting their use in transplantation and other diseases. Here we define a microRNA (miRNA)-messenger RNA (mRNA) interaction map that facilitates exploration into the role of miRNAs in cyclosporine-induced nephrotoxicity (CIN) and the gene pathways they regulate. Using photoactivatable ribonucleoside-enhanced crosslinking and immunoprecipitation (PAR-CLIP), we isolated RNAs associated with Argonaute 2 in the RNA-induced silencing complex (RISC) of cyclosporine A (CsA) treated and control human proximal tubule cells and identified mRNAs undergoing active targeting by miRNAs. CsA causes specific changes in miRNAs and mRNAs associated with RISC, thereby altering post-transcriptional regulation of gene expression. Pathway enrichment analysis identified canonical pathways regulated by miRNAs specifically following CsA treatment. RNA-seq performed on total RNA indicated that only a fraction of total miRNAs and mRNAs are actively targeted in the RISC, indicating that PAR-CLIP more accurately defines meaningful targeting interactions. Our data also revealed a role for miRNAs in calcineurin-independent regulation of JNK and p38 MAPKs caused by targeting of MAP3K1. Together, our data provide a novel resource and unique insights into molecular pathways regulated by miRNAs in CIN. The gene pathways and miRNAs defined may represent novel targets to reduce calcineurin induced nephrotoxicity.

A calcineurin antifungal strategy with analogs of FK506.

A novel antifungal strategy targeting the inhibition of calcineurin is described. To develop a calcineurin based inhibitor of pathogenic fungi, analogs of FK506 were synthesized that were able to permeate mammalian but not fungal cells. Antagonists in combination with FK506 were not immunosuppressive and retained antifungal activity in A. fumigatus. To reduce the dosage burden of the antagonist, murine oral PK was improved an order of magnitude relative to previous FK506 antagonists.

Long term renal survival in patients undergoing T-Cell depleted versus conventional hematopoietic stem cell transplants.

Calcineurin inhibitor (CNI)-sparing T-cell depleted (TCD) hematopoietic stem cell transplants (HSCTs) are presumed to be less nephrotoxic than conventional HSCTs. We evaluated incidence and risk factors for kidney failure and chronic kidney disease (CKD) in 231 TCD and 212 conventional HSCT recipients. Kidney failure required a median glomerular filtration rate (GFR) <60 ml/min/1.73 m2 for ⩾100 days anytime after 180-days post-HSCT. Two-year cumulative incidence (CI) of kidney failure was 42% in the conventional versus 31% in the TCD group (P=0.005). TCD, age, acute kidney injury and number of toxic CNI levels all impacted on kidney failure, which was associated with increased all-cause mortality (hazard ratio 2.86 (95% CI: 1.88-4.36), P<0.001). Renal recovery occurred in 28% of kidney failure patients whereas the remaining patients were defined to have CKD. In those with baseline GFR>60 ml/min/1.73 m2, only exposure to nephrotoxic medications was associated with CKD (P=0.033). In the myeloablative-conditioning subgroup only total body irradiation was associated with CKD (P=0.013). Of all patients, five (1.13%) required dialysis. These results confirm an impact of TCD on kidney failure but not CKD for which other risk factors such as radiation or nephrotoxic drug exposure may have a role.

Calcineurin inhibitor cyclosporine A activates renal Na-K-Cl cotransporters via local and systemic mechanisms.

Calcineurin dephosphorylates nuclear factor of activated T cells transcription factors, thereby facilitating T cell-mediated immune responses. Calcineurin inhibitors are instrumental for immunosuppression after organ transplantation but may cause side effects, including hypertension and electrolyte disorders. Kidneys were recently shown to display activation of the furosemide-sensitive Na-K-2Cl cotransporter (NKCC2) of the thick ascending limb and the thiazide-sensitive Na-Cl cotransporter (NCC) of the distal convoluted tubule upon calcineurin inhibition using cyclosporin A (CsA). An involvement of major hormones like angiotensin II or arginine vasopressin (AVP) has been proposed. To resolve this issue, the effects of CsA treatment in normal Wistar rats, AVP-deficient Brattleboro rats, and cultured renal epithelial cells endogenously expressing either NKCC2 or NCC were studied. Acute administration of CsA to Wistar rats rapidly augmented phosphorylation levels of NKCC2, NCC, and their activating kinases suggesting intraepithelial activating effects. Chronic CsA administration caused salt retention and hypertension, along with stimulation of renin and suppression of renal cyclooxygenase 2, pointing to a contribution of endocrine and paracrine mechanisms at long term. In Brattleboro rats, CsA induced activation of NCC, but not NKCC2, and parallel effects were obtained in cultured cells in the absence of AVP. Stimulation of cultured thick ascending limb cells with AVP agonist restored their responsiveness to CsA. Our results suggest that the direct epithelial action of calcineurin inhibition is sufficient for the activation of NCC, whereas its effect on NKCC2 is more complex and requires concomitant stimulation by AVP.

The significance of histological diagnosis in renal allograft biopsies in 2014.

In 2014, the renal allograft biopsy still represents the best available diagnostic 'gold' standard to assess reasons for allograft dysfunction. However, it is well recognized that histological lesion observed in the biopsy is of limited diagnostic specificity and that the Banff classification as the international diagnostic standard represents mere expert consensus. Here, we review the role of the renal allograft biopsy in different clinical and diagnostic settings. To increase diagnostic accuracy and to compensate for lack of specificity, the interpretation of biopsy pathology needs to be within the clinical context, primarily defined by time post-transplantation and patient-specific risk profile. With this in mind, similar histopathological patterns will lead to different conclusions with regard to diagnosis, disease grading and staging and thus to patient-specific clinical decision-making. Consensus generation for such integrated diagnostic approach, preferably including new molecular tools, represents the next challenge to the transplant community on its way to precision medicine in transplantation.

A randomized cross-over comparison of short-term exposure of once-daily extended release tacrolimus and twice-daily tacrolimus on renal function in healthy volunteers.

Calcineurin inhibitor nephrotoxicity remains an issue for transplant recipients. The pharmacokinetic profile (PK) of the once-daily tacrolimus extended release (Tac-ER) includes equivalent exposure [AUC(0-24 h) ] but lower Cmax versus twice-daily tacrolimus immediate release (Tac-IR). We hypothesized that the unique PK profiles would result in pharmacodynamic differences in renal function. Nineteen healthy male subjects were allocated to once-daily Tac-ER and twice-daily Tac-IR in a prospective, randomized, two period, cross-over study. Tacrolimus was titrated to achieve trough levels of 8-12 ng/ml. Twenty four hours ERPF and GFR estimated by para-aminohippurate and sinistrin clearance were performed at baseline and at the end of each 10-day dosing period. Mean Tac C0 was 11.0 ± 2.2 and 11.3 ± 1.8 ng/ml for Tac-ER and Tac-IR, respectively. The mean Effective 24 h renal plasma flow (ERPF) was significantly higher with Tac-ER compared with Tac-IR (658 ± 127 vs. 610 ± 93 ml/min/1.73 m(2) , P = 0.046). There was a trend to a greater mean GFR over 24 h for Tac-ER at 114.5 ± 13.6 ml/min/1.73 m(2) compared with 108.9 ± 9.7 ml/min/1.73 m(2) for Tac-IR, P = 0.116. Under controlled physiological conditions, ERPF was significantly improved with Tac-ER compared with Tac-IR, likely owing to the differing PKs of these tacrolimus preparations (ClinicalTrials.gov Identifier: NCT01681134).