Identification and characterization of kidney transplants with good glomerular filtration rate at 1 year but subsequent progressive loss of renal function

Sodium bicarbonate for kidney transplant recipients with metabolic acidosis in Switzerland: a multicentre, randomised, single-blind, placebo-controlled, phase 3 trial

BACKGROUND

Metabolic acidosis is common in kidney transplant recipients and is associated with declining graft function. Sodium bicarbonate treatment effectively corrects metabolic acidosis, but no prospective studies have examined its effect on graft function. Therefore, we aimed to test whether sodium bicarbonate treatment would preserve graft function and slow the progression of estimated glomerular filtration rate (GFR) decline in kidney transplant recipients.

METHODS

The Preserve-Transplant Study was a multicentre, randomised, single-blind, placebo-controlled, phase 3 trial at three University Hospitals in Switzerland (Zurich, Bern, and Geneva), which recruited adult (aged ≥18 years) male and female long-term kidney transplant recipients if they had undergone transplantation more than 1 year ago. Key inclusion criteria were an estimated GFR between 15 mL/min per 1·73 m2 and 89 mL/min per 1·73 m2, stable allograft function in the last 6 months before study inclusion (<15% change in serum creatinine), and a serum bicarbonate of 22 mmol/L or less. We randomly assigned patients (1:1) to either oral sodium bicarbonate 1·5-4·5 g per day or matching placebo using web-based data management software. Randomisation was stratified by study centre and gender using a permuted block design to guarantee balanced allocation. We did multi-block randomisation with variable block sizes of two and four. Treatment duration was 2 years. Acid-resistant soft gelatine capsules of 500 mg sodium bicarbonate or matching 500 mg placebo capsules were given at an initial dose of 500 mg (if bodyweight was <70 kg) or 1000 mg (if bodyweight was ≥70 kg) three times daily. The primary endpoint was the estimated GFR slope over the 24-month treatment phase. The primary efficacy analyses were applied to a modified intention-to-treat population that comprised all randomly assigned participants who had a baseline visit. The safety population comprised all participants who received at least one dose of study drug. The trial is registered with ClinicalTrials.gov, NCT03102996.

FINDINGS

Between June 12, 2017, and July 10, 2019, 1114 kidney transplant recipients with metabolic acidosis were assessed for trial eligibility. 872 patients were excluded and 242 were randomly assigned to the study groups (122 [50%] to the placebo group and 120 [50%] to the sodium bicarbonate group). After secondary exclusion of two patients, 240 patients were included in the intention-to-treat analysis. The calculated yearly estimated GFR slopes over the 2-year treatment period were a median -0·722 mL/min per 1·73 m2 (IQR -4·081 to 1·440) and mean -1·862 mL/min per 1·73 m2 (SD 6·344) per year in the placebo group versus median -1·413 mL/min per 1·73 m2 (IQR -4·503 to 1·139) and mean -1·830 mL/min per 1·73 m2 (SD 6·233) per year in the sodium bicarbonate group (Wilcoxon rank sum test p=0·51; Welch t-test p=0·97). The mean difference was 0·032 mL/min per 1·73 m2 per year (95% CI -1·644 to 1·707). There were no significant differences in estimated GFR slopes in a subgroup analysis and a sensitivity analysis confirmed the primary analysis. Although the estimated GFR slope did not show a significant difference between the treatment groups, treatment with sodium bicarbonate effectively corrected metabolic acidosis by increasing serum bicarbonate from 21·3 mmol/L (SD 2·6) to 23·0 mmol/L (2·7) and blood pH from 7·37 (SD 0·06) to 7·39 (0·04) over the 2-year treatment period. Adverse events and serious adverse events were similar in both groups. Three study participants died. In the placebo group, one (1%) patient died from acute respiratory distress syndrome due to SARS-CoV-2 and one (1%) from cardiac arrest after severe dehydration following diarrhoea with hypotension, acute kidney injury, and metabolic acidosis. In the sodium bicarbonate group, one (1%) patient had sudden cardiac death.

INTERPRETATION

In adult kidney transplant recipients, correction of metabolic acidosis by treatment with sodium bicarbonate over 2 years did not affect the decline in estimated GFR. Thus, treatment with sodium bicarbonate should not be generally recommended to preserve estimated GFR (a surrogate marker for graft function) in kidney transplant recipients with chronic kidney disease who have metabolic acidosis.

FUNDING

Swiss National Science Foundation.

Risk of end-stage kidney disease in kidney transplant recipients versus patients with native chronic kidney disease: multicentre unmatched and propensity-score matched analyses

BACKGROUND

In kidney transplant recipients (KTR), the end-stage kidney disease (ESKD) risk dependent on the risk factors acting in native chronic kidney disease (CKD) remains undefined.

METHODS

We compared risk and determinants of ESKD between 757 adult KTR and 1940 patients with native CKD before and after propensity-score (PS) analysis matched for unmodifiable risk factors [(age, sex, diabetes, cardiovascular disease and estimated glomerular filtration rate (eGFR)].

RESULTS

In unmatched cohorts, eGFR was lower in CKD versus KTR (45.9 ± 11.3 versus 59.2 ± 13.4 mL/min/1.73 m2, P < 0.001). During a median follow-up of 5.4 years, the unadjusted cumulative incidence of ESKD was consistently lower in unmatched KTR versus CKD. Conversely, in PS-matched analysis, the risk of ESKD in KTR was 78% lower versus CKD at 1 year of follow-up while progressively increased over time resulting similar to that of native CKD patients after 5 years and 2.3-fold higher than that observed in CKD at 10 years. R2 analysis in unmatched patients showed that the proportion of the outcome variance explained by traditional ESKD determinants was smaller in KTR versus native CKD (31% versus 70%). After PS matching, the risk of ESKD [hazard ratio (HR), 95% confidence interval (95% CI)] was significantly associated with systolic blood pressure (1.02, 1.01-1.02), phosphorus (1.31, 1.05-1.64), 24-h proteinuria (1.11, 1.05-1.17) and haemoglobin (0.85, 0.78-0.93) irrespective of KTR status. Similar data were obtained after matching also for modifiable risk factors.

CONCLUSIONS

In KTR, when compared with matched native CKD patients, the risk of ESKD is lower in the first 5 years and higher later on. Traditional determinants of ESKD account for one-third of the variability of time-to-graft failure.

Chronic Allograft Injury

With the incremental improvements in long-term kidney transplant survival, there is renewed focus on what causes failure of the transplanted allograft. Over the past decade, our understanding of the injuries that lead to loss of graft function over time has evolved. Chronic allograft injury includes both immune-mediated and nonimmune-mediated injuries, which may involve the organ donor, the recipient, or both. The targets of injury include the kidney tubular epithelium, the endothelium, and the glomerulus. As a response to injury, there are the expected tissue remodeling and repair processes. However, if inflammation persists, which is not uncommon in the transplant setting, the resulting maladaptive response is matrix deposition and/or fibrosis. This ultimately leads to declining graft function and, finally, failure. With our advancing knowledge of the multiple etiologies and mechanisms, enhanced by more recent cohort studies in humans, there is an opportunity to identify those at greater risk to initiate new strategies to ameliorate the process. Although the most recent studies focus on immune-mediated injuries, there is a critical need to identify both markers of injury and mechanisms of injury. In this review, we highlight the findings of recent studies, highlight the potential therapeutic targets, and identify the continued unmet need for understanding the mechanisms of late graft failure.

Progressive decline of function in renal allografts with normal 1-year biopsies: Gene expression studies fail to identify a classifier

Histologic findings on 1-year biopsies such as inflammation with fibrosis and transplant glomerulopathy predict renal allograft loss by 5 years. However, almost half of the patients with graft loss have a 1-year biopsy that is either normal or has only interstitial fibrosis. The goal of this study was to determine if there was a gene expression profile in these relatively normal 1-year biopsies that predicted subsequent decline in renal function. Using transcriptome microarrays we measured intragraft mRNA levels in a retrospective Discovery cohort (170 patients with a normal/minimal fibrosis 1-year biopsy, 54 with progressive decline in function/graft loss and 116 with stable function) and developed a nested 10-fold cross-validated gene classifier that predicted progressive decline in renal function (positive predictive value = 38 ± 34%%; negative predictive value = 73 ± 30%, c-statistic = .59). In a prospective, multicenter Validation cohort (270 patients with Normal/Interstitial Fibrosis [IF]), the classifier had a 20% positive predictive value, 85% negative predictive value and .58 c-statistic. Importantly, the majority of patients with graft loss in the prospective study had 1-year biopsies scored as Normal or IF. We conclude predicting graft loss in many renal allograft recipients (i.e., those with a relatively normal 1-year biopsy and eGFR > 40) remains difficult.

Change in Estimated GFR and Risk of Allograft Failure in Patients Diagnosed With Late Active Antibody-mediated Rejection Following Kidney Transplantation

BACKGROUND

There are challenges in designing adequate, well-controlled studies of patients with active antibody-mediated rejection (AMR) after kidney transplantation (KTx).

METHODS

We assessed the functional relationship between change in estimated glomerular filtration rate (eGFR) following the diagnosis of AMR and the risk of subsequent death-censored graft failure using the joint modeling framework. We included recipients of solitary KTx between 1995 and 2013 at 4 transplant centers diagnosed with biopsy-proven active AMR at least 1 year post-KTx, who had a minimum of 3-year follow-up.

RESULTS

A total of 91 patients across participating centers were included in the analysis. Of the 91 patients, n = 54 patients (59%) met the death-censored graft failure endpoint and n = 62 patients (68%) met the all-cause graft failure composite endpoint. Kaplan-Meier death-censored graft survival rates at 12, 36, and 60 months postdiagnosis of AMR pooled across centers were 88.9%, 58.9%, and 36.4%, respectively. Spaghetti plots indicated a linear trend in the change in eGFR, especially in the first 12 months postdiagnosis of active AMR. A significant change in eGFR was observed within the first 12 months postdiagnosis of active AMR, getting worse by a factor of -0.757 mL/min/1.73 m2 per month during the 12-month analysis period (a delta of -9.084 mL/min/1.73 m2 at 1 y). Notably, an extrapolated 30% improvement in the slope of eGFR in the first 12 months was associated with a 10% improvement in death-censored graft failure at 5 years.

CONCLUSIONS

If prospectively validated, this study may inform the design of pivotal clinical trials for therapies for late AMR.

Everolimus-facilitated calcineurin inhibitor reduction in Asian de novo kidney transplant recipients: Two-year results from the subgroup analysis of the TRANSFORM study

Objective

We analyzed the efficacy and safety of an everolimus with reduced‐exposure calcineurin inhibitor (EVR+rCNI) versus mycophenolic acid with standard‐exposure CNI (MPA+sCNI) regimen in Asian patients from the TRANSFORM study.

Methods

In this 24‐month, open‐label study, de novo kidney transplant recipients (KTxRs) were randomized (1:1) to receive EVR+rCNI or MPA+sCNI, along with induction therapy and corticosteroids.

Results

Of the 2037 patients randomized in the TRANSFORM study, 293 were Asian (EVR+rCNI, N = 136; MPA+sCNI, N = 157). At month 24, EVR+rCNI was noninferior to MPA+sCNI for the binary endpoint of estimated glomerular filtration rate (eGFR) < 50 ml/min/1.73 m² or treated biopsy‐proven acute rejection (27.0% vs. 29.2%, P = .011 for a noninferiority margin of 10%). Graft loss and death were reported for one patient each in both arms. Mean eGFR was higher in EVR+rCNI versus MPA+sCNI (72.2 vs. 66.3 ml/min/1.73 m², P = .0414) even after adjusting for donor type and donor age (64.3 vs. 59.3 ml/min/1.73 m², P = .0582). Overall incidence of adverse events was comparable. BK virus (4.4% vs. 12.1%) and cytomegalovirus (4.4% vs. 13.4%) infections were significantly lower in the EVR+rCNI arm.

Conclusion

This subgroup analysis in Asian de novo KTxRs demonstrated that the EVR+rCNI versus MPA+sCNI regimen provides comparable antirejection efficacy, better renal function, and reduced viral infections (NCT01950819).

HLA antibodies are associated with deterioration of kidney allograft function irrespective of donor specificity

BACKGROUND

Donor-specific antibodies are associated with high immunological risk and poor allograft outcome. Risk and clinical relevance of non-donor-specific HLA antibodies is less clear.

METHODS

A retrospective single-center study was conducted in all patients receiving a first kidney transplant at the University hospital of Zürich between 01/2006 and 02/2015. Patients were stratified into 3 groups having either no HLA antibodies at all (NoAB), HLA antibodies with donor specificity (DSA) and HLA antibodies without donor specificity (NonDSA). Allograft outcome was assessed using the slope of the estimated glomerular filtration rate (eGFR slope) starting at 12 months after transplantation.

RESULTS

During a median follow-up of 1808 days HLA antibodies were detected in 106 of 238 eligible patients (44%). Out of these, 73 patients (69%) had DSA and 33 patients (31%) had NonDSA only. Medium-term allograft function, as determined by eGFR slope over three years, improved in patients with NoAB (months 12-48: +0.7 ml/min/1.73 m²) but deteriorated significantly in patients with both DSA (months 12-48: -1.5 ml/min per1.73 m²/year, p = 0.015) and NonDSA (months 12-48: -1.8 ml/min per1.73 m²/year, p = 0.03) as compared to the group with NoAB.

CONCLUSION

Both, donor-specific and non-donor-specific HLA antibodies are associated with medium-term kidney allograft dysfunction as compared to patients with no HLA antibodies.

Predicting Clinical Outcome in Expanded Criteria Donor Kidney Transplantation: A Retrospective Cohort Study

Background:

The gaps in organ supply and demand necessitate the use of expanded criteria donor (ECD) kidneys.

Objective:

To identify which pre-transplant and post-transplant predictors are most informative regarding short- and long-term ECD transplant outcomes.

Design:

Retrospective cohort study.

Setting:

Single center, Quebec, Canada.

Patients:

The patients were 163 consecutive first-time ECD kidney only transplant recipients who underwent transplantation at McGill University Health Centre (MUHC) between January 1, 2008 and December 31, 2014 and had frozen section wedge procurement biopsies.

Measurements:

Short-term graft outcomes, including delayed graft function and 1-year estimated glomerular filtration rate (eGFR), as well as long-term outcomes including all-cause graft loss (defined as return to dialysis, retransplantation, and death with function).

Methods:

Pre-transplant donor, recipient, and transplant characteristics were assessed as predictors of transplant outcomes. The added value of post-transplant predictors, including longitudinal eGFR, was also assessed using time-varying Cox proportional hazards models.

Results:

In univariate analyses, among the pre-transplant donor characteristics, histopathologic variables did not show evidence of association with delayed graft function, 1-year post-transplant eGFR or all cause graft loss. Recipient age was associated with all-cause graft loss (hazard ratio: 1.038 [95% confidence interval: 1.002-1.075] and the model produced only modest discrimination (C-index: 0.590; standard error [SE]: 0.045). Inclusion of time-dependent post-transplant eGFR improved the model’s prediction accuracy (C-index: 0.711; SE = 0.047). Pre-transplant ECD characteristics were not associated with long-term survival, whereas post-transplant characteristics allowed better model discrimination.

Limitations:

Single-center study, small sample size, and potential incomplete capture of all covariate data.

Conclusions:

Incorporation of dynamic prediction models into electronic health records may enable timely mitigation of ECD graft failure risk and/or facilitate planning for renal replacement therapies. Histopathologic findings on preimplantation biopsies have a limited role in predicting long-term ECD outcomes.

Trial registration:

Not applicable.

Determinants of the intercept and slope of glomerular filtration rate in recipients of a live donor kidney transplant

Background

Donor kidney function is considered a critical determinant of allograft survival after live donor (LD) kidney transplantation, but its independent impact on the evolution of graft function is less well defined. The objective of this study was to dissect the relative contribution of LD kidney function to baseline estimated glomerular filtration rate (eGFR) of recipients and its decline.

Methods

In this study 91 LD kidney transplantations performed between 2007 and 2015 were included. The eGFR of donated kidneys (eGFR-dk) was calculated from total LD eGFR (eGFR-dt) based on the results of isotope nephrography. Recipient eGFR (eGFR-r) determined 6‑monthly until 36 months posttransplantation served as dependent variable in mixed linear models estimating changes in baseline allograft function (intercept) and eGFR‑r slope. Models were adjusted either for eGFR-dk or eGFR-dt, in addition to other potential confounders.

Results

Overall, unadjusted mean eGFR‑r at baseline (6 months) and its annual decline in allograft function were 56.5 mL/min/1.73 m² and −0.2 mL/min/1.73 m², respectively. In multivariate analysis, eGFR-dk impacted on baseline eGFR‑r (0.6 mL/min/1.73 m² mean estimated increase per unit; P = 0.02) but not on its slope. In the eGFR-dt-adjusted model, a marginal effect was observed for LD age (P = 0.05). Both models identified antibody-mediated rejection (ABMR) as the strongest risk factor of accelerated loss of allograft function (eGFR‑r slope: approximately −6 mL/min/1.73 m² per year; P ≤ 0.02).

Conclusion

Donor-related characteristics, most prominently the function of donated kidneys and LD age, were predictive of eGFR at baseline. The ABMR was identified as the cardinal cause of progressive deterioration of allograft function.

Everolimus with Reduced Calcineurin Inhibitor Exposure in Renal Transplantation

Background Everolimus permits reduced calcineurin inhibitor (CNI) exposure, but the efficacy and safety outcomes of this treatment after kidney transplant require confirmation.Methods In a multicenter noninferiority trial, we randomized 2037 de novo kidney transplant recipients to receive, in combination with induction therapy and corticosteroids, everolimus with reduced-exposure CNI (everolimus arm) or mycophenolic acid (MPA) with standard-exposure CNI (MPA arm). The primary end point was treated biopsy-proven acute rejection or eGFR<50 ml/min per 1.73 m² at post-transplant month 12 using a 10% noninferiority margin.Results In the intent-to-treat population (everolimus n=1022, MPA n=1015), the primary end point incidence was 48.2% (493) with everolimus and 45.1% (457) with MPA (difference 3.2%; 95% confidence interval, -1.3% to 7.6%). Similar between-treatment differences in incidence were observed in the subgroups of patients who received tacrolimus or cyclosporine. Treated biopsy-proven acute rejection, graft loss, or death at post-transplant month 12 occurred in 14.9% and 12.5% of patients treated with everolimus and MPA, respectively (difference 2.3%; 95% confidence interval, -1.7% to 6.4%). De novo donor-specific antibody incidence at 12 months and antibody-mediated rejection rate did not differ between arms. Cytomegalovirus (3.6% versus 13.3%) and BK virus infections (4.3% versus 8.0%) were less frequent in the everolimus arm than in the MPA arm. Overall, 23.0% and 11.9% of patients treated with everolimus and MPA, respectively, discontinued the study drug because of adverse events.Conclusions In kidney transplant recipients at mild-to-moderate immunologic risk, everolimus was noninferior to MPA for a binary composite end point assessing immunosuppressive efficacy and preservation of graft function.

A Randomized Trial of Bortezomib in Late Antibody-Mediated Kidney Transplant Rejection

Late antibody-mediated rejection (ABMR) is a leading cause of kidney allograft failure. Uncontrolled studies have suggested efficacy of the proteasome inhibitor bortezomib, but no systematic trial has been undertaken to support its use in ABMR. In this randomized, placebo-controlled trial (the Bortezomib in Late Antibody-Mediated Kidney Transplant Rejection [BORTEJECT] Trial), we investigated whether two cycles of bortezomib (each cycle: 1.3 mg/m² intravenously on days 1, 4, 8, and 11) prevent GFR decline by halting the progression of late donor-specific antibody (DSA)-positive ABMR. Forty-four DSA-positive kidney transplant recipients with characteristic ABMR morphology (median time after transplant, 5.0 years; pretransplant DSA documented in 19 recipients), who were identified on cross-sectional screening of 741 patients, were randomly assigned to receive bortezomib (n=21) or placebo (n=23). The 0.5-ml/min per 1.73 m² per year (95% confidence interval, -4.8 to 5.8) difference detected between bortezomib and placebo in eGFR slope (primary end point) was not significant (P=0.86). We detected no significant differences between bortezomib- and placebo-treated groups in median measured GFR at 24 months (33 versus 42 ml/min per 1.73 m²; P=0.31), 2-year graft survival (81% versus 96%; P=0.12), urinary protein concentration, DSA levels, or morphologic or molecular rejection phenotypes in 24-month follow-up biopsy specimens. Bortezomib, however, associated with gastrointestinal and hematologic toxicity. In conclusion, our trial failed to show that bortezomib prevents GFR loss, improves histologic or molecular disease features, or reduces DSA, despite significant toxicity. Our results reinforce the need for systematic trials to dissect the efficiency and safety of new treatments for late ABMR.

High urinary interleukin-2 in late post-transplant period portends a risk of decline in kidney allograft function: a preliminary study

BACKGROUND

Predictive factors for the rate of decline in kidney allograft function beyond the first post-transplant year have not been thoroughly studied. We aimed to determine whether a single measurement of serum and urinary interleukin 2, interleukin 8 and interleukin 10 at 1-15 years after kidney transplantation could predict a decline in estimated glomerular filtration rate (eGFR) over a 2-year period.

RESULTS

Greater serum concentrations of interleukin 8 and interleukin 10 in 30 recipients of kidney allograft at enrollment were associated with lower eGFR after 1 year (beta = - 0.616, p = 0.002 and beta = - 0.393, p = 0.035, respectively), whereas serum concentrations of interleukin 8 also demonstrated significant association with eGFR after 2 years of follow-up (beta = - 0.594, p = 0.003). Higher urinary interleukin 2 concentrations were associated with lower eGFR at baseline (rho = - 0.368, p = 0.049) and after the first (beta = - 0.481, p = 0.008) and the second year (beta = - 0.502, p = 0.006) of follow-up. Higher urinary interleukin 2 concentrations predicted certain decline in eGFR of ≥ 25% from baseline after 1 year of follow-up in logistic regression: odds ratio = 2.94, confidence interval 1.06-8.18, p = 0.038. When combined with time after transplantation, urinary interleukin 2 demonstrated good accuracy in predicting rapid decline in eGFR by > -5 mL/min/1.73 m2/year (area under the receiver-operator characteristic curve: 0.855, confidence interval 0.687-1.000, and p = 0.008).

CONCLUSIONS

Our findings suggest that urinary interleukin 2 in the late period after kidney transplantation has promise in identifying patients who are at risk for progressive loss of graft function in a short-time perspective and need closer monitoring.

The role of sildenafil in the development of transplant arteriosclerosis in rat aortic grafts

Chronic rejection (CR), which is characterized histologically by progressive graft arteriosclerosis, remains a significant barrier to the long-term survival of a graft. Sildenafil has been shown to protect vascular endothelial cells. In this study, we found that sildenafil significantly reduces the thickness of transplant vascular intima in a rat aortic transplant model. Moreover, sildenafil dramatically decreased the expression of transforming growth factor-β1 (TGF-β1), vascular endothelial growth factor (VEGF), and α-smooth muscle actin (α-SMA) in the grafted aortas and increased the concentrations of cyclic guanosine monophosphate (cGMP) and endothelial nitric oxide synthase (eNOS) in serum. Furthermore, the ratio of regulatory T (Treg) cells and the expression of FoxP3 were increased, and the ratio of Th17 cells was decreased in the sildenafil-treated group. These results demonstrate that sildenafil enhances nitric oxide (NO) signaling by increasing the availability of cGMP, leading to an increase in the ratio of Treg/Th17 cells to attenuate transplant arteriosclerosis in a rat aortic transplant model.

High Urinary Aspartate Aminotransferase in the Late Posttransplant Period Predicts Rapid, Progressive Decline in Kidney Allograft Function

OBJECTIVES

Scant information is available on factors for predicting the rate of decline in kidney allograft function beyond 1 year posttransplant.We investigated whether urinary enzymes (alanine aminotransferase, alkaline phosphatase, aspartate aminotransferase, N-acetyl-β-D-hexosaminidase, and ε-glutamyl transpeptidase) in the late postoperative period can predict the decline in estimated glomerular filtration rate.

MATERIALS AND METHODS

In 79 kidney allograft recipients 1 to 17 years after kidney transplant, we assessed a value of urinary enzymes single measurement for predicting the slope of estimated glomerular filtration rate, rapid decline in estimated glomerular filtration rate (> 5 mL/min/1.73 m² /y), and significant decline in estimated glomerular filtration rate (≥ 25% from baseline) during a 2-year period.

RESULTS

At baseline, patients with estimated glomerular filtration rate < 60 mL/min/1.73 m² (n = 54) differed from those with estimated glomerular filtration rate ≥ 60 mL/min/1.73 m² (n = 25) only in their lower median urinary alanine aminotransferase:creatinine ratio (expressed as U/L:mmol/L): 0.055 versus 0.222 (P = .011). Higher urinary activity of aspartate aminotransferase at baseline predicted the negative-slope value for estimated glomerular filtration rate (beta, -0.279; standard error, 0.131; P = .037) and decline in estimated glomerular filtration rate of > 5 mL/min/1.73 m ²/year (odds ratio, 2.06; 95% confidence interval, 1.10-3.83; P = .023) over 2 years. It also predicted the drop in estimated glomerular filtration rate ≥ 25% after 1 year (odds ratio, 2.62; 95% confidence interval, 1.07-6.37; P = .034) and 2 years (odds ratio, 2.75; 95% confidence interval, 1.12-6.73; P =.027). Combined with time after transplant, urinary aspartate aminotransferase had good power for predicting an estimated glomerular filtration rate decrease ≥ 25% after 2 years of follow-up.

CONCLUSIONS

Higher urinary activity of aspartate aminotransferase in the late posttransplant period is useful for identifying transplant patients who are at risk for progressive loss of graft function.

NFATC1 genotypes affect acute rejection and long-term graft function in cyclosporine-treated renal transplant recipients

AIM

To investigate the effects of SNPs in the cyclophilin A/calcineurin/nuclear factor of activated T-cells (NFATs) pathway genes (PPIA, PPP3CB, PPP3R1, NFATC1 and NFATC2) on cyclosporine (CsA) efficacy in renal transplant recipients.

MATERIALS & METHODS

Seventy-six tag SNPs were detected in 155 CsA-treated renal recipients with at least a 5-year follow-up. The associations of SNPs with acute rejection, nephrotoxicity, pneumonia and estimated glomerular filtration rate post transplant were explored.

RESULTS

NFATC1 rs3894049 GC was a risk factor for acute rejection compared with CC carriers (p = 0.0005). NFATC1 rs2280055 TT carriers had a more stable estimated glomerular filtration rate level than CC (p = 0.0004).

CONCLUSION

Detecting NFATC1 polymorphisms could help predict CsA efficacy in renal transplant patients.

Differential Characteristics of Kidney Transplant Recipients According to 1-Year Chronic Kidney Disease Stage 3a and Stage 3b Graft Function

The outcomes of transplantation have improved, but more than 50% of kidney transplantation (KT) recipients are still reported to have renal function of chronic kidney disease (CKD) stage 3 at 1 year after KT. We reviewed all 1235 patients who received a KT in our institution between 2008 and 2012. Among these recipients, 77 and 289 cases were included in the estimated glomerular filtration rate (eGFR) at 1 year after KT 30-44 (CKD stage 3b) group and eGFR 45-59 (CKD stage 3a) group, respectively. Longer duration of dialysis (odds ratio [OR] = 1.007, 95% confidence interval [CI], 1.000-1.014, P = 0.047), older donors (OR = 1.064, 95% CI, 1.031-1.098, P < 0.001), delayed graft function (OR = 3.601, 95% CI, 1.031-1.098, P < 0.001), BK virus infection (OR = 2.567, 95% CI, 1.242-5.305, P = 0.011), and pneumonia (OR = 4.451, 95% CI, 1.388-14.279, P = 0.012) were contributing factors to eGFR 30-44 mL/min. Especially, ureteral stricture occurred more frequently in eGFR 30-44 group of deceased donor KT. However, acute rejection was not a significant risk factor of lower eGFR. Graft survival was better in the eGFR 45-59 group. However, this difference was smaller in deceased donor KT. Infections and urologic complications are also important contributing factors of lower graft function in CKD stage 3. In addition, dividing CKD stage 3 into subgroups might be more useful in living donor kidney transplantation.

Urinary Lysosomal Enzyme Activities and Albuminuria in Ghanaian Patients with Type 2 Diabetes Mellitus

Renal tubular lysosomal enzyme activities like alanine aminopeptidase (AAP) and N-acetyl-β-D-glucosaminidase (NAG) have been shown to increase in patients developing diabetic nephropathy and nephrosclerosis. This study aimed to determine the activities of N-acetyl-β-D-glucosaminidase and alanine aminopeptidase and albumin concentration in urine samples of patients with type 2 diabetes. One hundred and thirty (65 type 2 diabetic and 65 nondiabetic) subjects participated in this study. Blood samples were drawn for measurements of fasting blood glucose, albumin (Alb), lipids, and creatinine (Cr). Early morning spot urine samples were also collected for activities of alanine aminopeptidase (AAP), N-acetyl-β-D-glucosaminidase (NAG), and concentration of albumin (U-Alb) and creatinine (U-Cr). Both NAG/Cr and AAP/Cr were significantly increased in diabetic subjects compared to controls (p < 0.001). There was positive correlation between NAG/Cr and Alb/Cr (r = 0.49, p < 0.001) and between NAG/Cr and serum creatinine (r = 0.441, p < 0.001). A negative correlation was found between NAG/Cr and eGFR (r = −0.432, p < 0.05). 9.3% and 12% of diabetics with normoalbuminuria had elevated levels of AAP/Cr and NAG/Cr, respectively. We conclude that measuring the urinary enzymes activities (NAG/Cr and AAP/Cr) could be useful as a biomarker of early renal involvement in diabetic complications.

Predicting Individual Renal Allograft Outcomes Using Risk Models with 1-Year Surveillance Biopsy and Alloantibody Data

The ability to predict outcomes for individual patients would be a significant advance for not only counseling, but also identifying those for whom interventions may be needed. The goals of this study were to validate an existing risk prediction score that incorporates easily obtainable clinical factors and determine if histologic findings at 1-year surveillance biopsy and/or serum donor-specific alloantibody status could improve predictability of graft loss by 5 years. We retrospectively studied 1465 adults who received a solitary kidney transplant between January of 1999 and December of 2008 and had sufficiently detailed 5-year follow-up data for modeling. In this cohort, the Birmingham risk model (incorporating recipient factors at 1 year, including age, sex, ethnicity, renal function, proteinuria, and prior acute rejection) predicted death-censored and overall graft survival (c statistics =0.84 and 0.78, respectively). The presence of glomerulitis or chronic interstitial fibrosis (g and ci scores by Banff, respectively) on 1-year biopsy specimens independently correlated with graft loss by 5 years. Adding these variables to the model for death-censored graft loss increased predictability (c statistic =0.90), improved calibration (ability to stratify risk from high to low), and reclassified risk of failure in 29% of patients. Adding the presence of donor-specific alloantibody at 1 year did not improve predictability or reclassification but did improve calibration marginally. We conclude that, at 1 year after kidney transplant, a risk model of graft survival that incorporates clinical factors and histologic findings at surveillance biopsy is highly predictive of individual risk and well calibrated.

MicroRNA biomarkers in clinical renal disease: from diabetic nephropathy renal transplantation and beyond

Chronic Kidney Disease (CKD) is a common health problem affecting 1 in 12 Americans. It is associated with elevated risks of mortality, cardiovascular disease, and high costs for the treatment of renal failure with dialysis or transplantation. Advances in CKD care are impeded by the lack of biomarkers for early diagnosis, assessment of the extent of tissue injury, estimation of disease progression, and evaluation of response to therapy. Such biomarkers should improve the performance of existing measures of renal functional impairment (estimated glomerular filtration rate, eGFR) or kidney damage (proteinuria). MicroRNAs (miRNAs) a class of small, non-coding RNAs that act as post-transcriptional repressors are gaining momentum as biomarkers in a number of disease areas. In this review, we examine the potential utility of miRNAs as promising biomarkers for renal disease. We explore the performance of miRNAs as biomarkers in two clinically important forms of CKD, diabetes and the nephropathy developing in kidney transplant recipients. Finally, we highlight the pitfalls and opportunities of miRNAs and provide a broad perspective for the future clinical development of miRNAs as biomarkers in CKD beyond the current gold standards of eGFR and albuminuria.

High Serum Level of β2-Microglobulin in Late Posttransplant Period Predicts Subsequent Decline in Kidney Allograft Function: A Preliminary Study

BACKGROUND

Identification of patients at risk for kidney allograft (KAG) failure beyond the first posttransplant year is an unmet need. We aimed to determine whether serum beta-2-microglobulin (β2MG) in the late posttransplant period could predict a decline in KAG function.

METHODS

We assessed a value of single measurement of serum β2MG at one to seventeen years after transplantation in predicting the estimated glomerular filtration rate (eGFR) and the decline in eGFR over a period of two years in 79 recipients of KAG.

RESULTS

At baseline serum β2MG concentration was higher (P = 0.011) in patients with allograft dysfunction: 8.67 ± 2.48 µg/mL versus those with satisfactory graft function: 6.67 ± 2.13 µg/mL. Higher β2MG independently predicted the lower eGFR, the drop in eGFR by ≥25% after one and two years, and the value of negative eGFR slope. When combined with proteinuria and acute rejection, serum β2MG had excellent power in predicting certain drop in eGFR after one year (AUC = 0.910). In conjunction with posttransplant time serum β2MG had good accuracy in predicting certain eGFR drop after two years (AUC = 0.821).

CONCLUSIONS

Elevated serum β2MG in the late posttransplant period is useful in identifying patients at risk for rapid loss of graft function.

Intravenous immunoglobulins and rituximab therapy for severe transplant glomerulopathy in chronic antibody-mediated rejection: a pilot study

Outcome of patients with transplant glomerulopathy (TG) is poor. Using B-cell targeting molecules represent a rational strategy to treat TG during chronic antibody-mediated rejection. In this pilot study, 21 patients with this diagnosis received four doses of intravenous immunoglobulins and two doses of rituximab (IVIG/RTX group). They were retrospectively compared with a untreated control group of 10 patients. At 24 months post-biopsy, graft survival was similar and poor between the treated and the untreated group, 47% vs. 40%, respectively, p = 0.69. This absence of response of IVIG/RTX treatment was observed, regardless the phenotype of TG. Baseline estimated glomerular filtration rate (eGFR) and decline in eGFR during the first six months after the treatment were risk factors associated with 24-month graft survival. The IVIG/RTX therapy had a modest effect on the kinetics of donor-specific alloantibodies at M24, compared to the untreated group, not associated with an improvement in graft survival. The mean number of adverse events per patient was higher in the IVIG/RTX group than in the control group (p = 0.03). Taken together, IVIG/RTX treatment for severe TG during chronic antibody-mediated rejection does not seem to change the natural history of TG and is associated with a high incidence of adverse events.

Modernization of Chronic Allograft Injury Research: Better Biomarkers, Better Studies, Better Outcomes

Despite dramatic improvements in acute rejection rates and short-term allograft survival, long-term allograft survival remains unchanged in the modern era, largely due to chronic allograft injury, a progressive disease that is common across all solid organ transplantation but has no proven treatment. Studies of novel diagnostic and therapeutic strategies for chronic allograft injury have been relatively sparse, in part due to the time and expense required to conduct traditional long-term clinical studies of a variably progressive disease. In this article, we review the pathophysiology of chronic allograft injury, including recent insights into key mechanisms of the disease. We discuss the barriers to progress in chronic allograft injury research and present alternative approaches to study design that could accelerate improvements in diagnosis, prevention, or treatment of the disease. We integrate these approaches with emerging biomarkers and surrogate endpoints into a model clinical study of chronic renal allograft injury, providing a framework for modern study design in solid organ transplantation.

Considerations for a Primary Care Physician Assistant in Treating Kidney Transplant Recipients

The escalating amount of kidney transplant recipients (KTRs) represents a significant dilemma for primary care providers. As the number of physician assistants (PAs) has been steadily increasing in primary care in the United States, the utilization of these healthcare professionals presents a solution for the care of post-kidney transplant recipients. A physician assistant (PA) is a state licensed healthcare professional who practices medicine under physician supervision and can alleviate some of the increasing demands for primary patient care. Here we provide an outline of the crucial components and considerations for PAs caring for kidney transplant recipients. These include renal function and routine screenings, drug monitoring (both immunosuppressive and therapeutic), pre-existing and co-existing conditions, immunizations, nutrition, physical activity, infection, cancer, and the patient's emotional well-being. PAs should routinely monitor renal function and blood chemistry of KTRs. Drug monitoring of KTRs is a crucial responsibility of the PA because of the possible side-effects and potential drug-drug interactions. Therefore, PAs should obtain a careful and detailed patient history from KTRs. PAs should be aware of pre- and co-existing conditions of KTRs as this impacts treatment decisions. Regarding immunization, PAs should avoid administering vaccines containing live or attenuated viruses to KTRs. Because obesity following kidney transplantation is associated with decreased allograft survival, PAs should encourage KTRs to maintain a balanced diet with limited sugar. In addition, KTRs should be urged to gradually increase their levels of physical activity over subsequent years following surgery. PAs should be aware that immunosuppressive medications diminish immune defenses and make KTRs more susceptible to bacterial, viral, and fungal infections. Moreover, KTRs should be screened routinely for cancer due to the higher risk of development from immunosuppressive therapy. PAs must remain cognizant of the emotional well-being of the KTR, as many transplant patients struggle with fear, frustration, and acceptance.

Through a glass darkly: seeking clarity in preventing late kidney transplant failure

A common lament is that long-term kidney transplant outcomes remain the same despite improvements in early graft survival. To be fair, progress has been made-in both our understanding of chronic injury and modestly, graft survival. However, we are still a long way from actually solving this important and difficult problem. In this review, we outline recent data supporting the existence of several causes of renal allograft loss, the incidences of which peak at different time points after transplantation. On the basis of this broadened concept of chronic renal allograft injury, we examine the challenges of clinical trial design in long-term studies, including the use of surrogate end points and biomarkers. Finally, we suggest a path forward that, ultimately, may improve long-term renal allograft survival.

Restoration of renal function does not correct impairment of uremic HDL properties

Cardiovascular disease remains the leading cause of death in renal transplant recipients, but the underlying causative mechanisms for this important problem remain elusive. Recent work has indicated that qualitative alterations of HDL affect its functional and compositional properties in ESRD. Here, we systematically analyzed HDL from stable renal transplant recipients, according to graft function, and from patients with ESRD to determine whether structural and functional properties of HDL remain dysfunctional after renal transplantation. Cholesterol acceptor capacity and antioxidative activity, representing two key cardioprotective mechanisms of HDL, were profoundly suppressed in kidney transplant recipients independent of graft function and were comparable with levels in patients with ESRD. Using a mass spectroscopy approach, we identified specific remodeling of transplant HDL with highly enriched proteins, including α-1 microglobulin/bikunin precursor, pigment epithelium-derived factor, surfactant protein B, and serum amyloid A. In conclusion, this study demonstrates that HDL from kidney recipients is uniquely altered at the molecular and functional levels, indicating a direct pathologic role of HDL that could contribute to the substantial cardiovascular risk in the transplant population.