Early inhibition of the renin-angiotensin system improves the long-term graft survival of single pediatric donor kidneys transplanted in adult recipients

Impact of Renin-Angiotensin System Blockade on Mortality and Allograft Loss among Renal Transplant Recipients: A Systematic Review and Meta-Analysis

INTRODUCTION

The blockade of the renin-angiotensin system (RAS) has a beneficial effect on reducing the levels of proteinuria and blood pressure in patients with chronic kidney disease (CKD) and reduces the risk of developing end-stage kidney disease in CKD patients. Nonetheless, a debate persists regarding the impact of RAS inhibitors on outcomes such as mortality and graft survival in renal transplant patients. To assess the effect of RAS inhibitors on graft recipients in the past decade, we conducted a systematic review and meta-analysis.

METHODS

We searched Embase, PubMed, and the Cochrane Central Register of Clinical Trials from January 1, 2012, to August 1, 2022. We included 14 articles, comprising 5 randomized controlled trials (RCTs) and 9 cohort studies, including 45,377 patients. These studies compared patient or graft survival between an RAS inhibitor treatment arm and a control arm.

RESULTS

The meta-analysis revealed that RAS blockade was significantly associated with lower mortality in cohort studies (risk ratio [RR] = 0.66, 95% confidence interval [CI]: 0.55-0.79), reduced allograft loss in cohort studies (RR = 0.62, 95% CI: 0.54-0.71), and significant changes in systolic blood pressure in RCTs. Subgroup analysis of the groups of interest (interventions involving RAS blockade, follow-up period of ≥5 years) showed consistently reduced mortality (RR = 0.67, 95% CI: 0.56-0.81) and reduced allograft loss (RR = 0.61, 95% CI: 0.54-0.70).

CONCLUSIONS

Our results demonstrated that the application of RAS blockade among renal transplant recipients was associated with lower mortality and allograft loss in cohort studies but not in RCTs. More powered clinical trials are needed to evaluate the effects of RAS blockade in renal transplant recipients.

Hypothermic Perfusion Modifies the Association Between Anti-LG3 Antibodies and Delayed Graft Function in Kidney Recipients

We previously reported associations between autoantibodies to the LG3 fragment of perlecan, anti-LG3, and a higher risk of delayed graft function (DGF) in kidney transplant recipients. Here, we aimed to determine whether some factors that modulate ischemia-reperfusion injury (IRI) can modify this association. We performed a retrospective cohort study in kidney transplant recipients in 2 university-affiliated centers. In 687 patients, we show that high pre-transplant anti-LG3 are associated with DGF when the kidney is transported on ice (odds ratio (OR): 1.75, 95% confidence interval 1.02-3.00), but not when placed on hypothermic perfusion pump (OR: 0.78, 95% CI 0.43-1.37). In patients with DGF, high pre-transplant anti-LG3 are associated with a higher risk of graft failure (subdistribution hazard ratio (SHR): 4.07, 95% CI: 1.80, 9.22), while this was not the case in patients with immediate graft function (SHR: 0.50, 95% CI 0.19, 1.29). High anti-LG3 levels are associated with a higher risk of DGF in kidneys exposed to cold storage, but not when hypothermic pump perfusion is used. High anti-LG3 are also associated with a higher risk of graft failure in patients who experience DGF, a clinical manifestation of severe IRI.

Excellent Clinical Long-Term Outcomes of Kidney Transplantation From Small Pediatric Donors (Age ≤ 5 Years) Despite Early Hyperfiltration Injury

Background:

The use of small pediatric donors (age ≤ 5 years and body weight < 20kg) for adult transplant recipients is still regarded controversially in terms of early complications, long-term outcomes, and development of hyperfiltration injury due to body size mismatch.

Objective:

To investigate long-term outcomes of adult renal allograft recipients receiving a kidney from small pediatric donor (SPD) in terms of kidney function and early features of hyperfiltration injury such as histological changes and proteinuria.

Design:

Retrospective, single center study.

Settings:

Transplant center of the University Hospital of Basel, Switzerland.

Patients:

Adult renal allograft recipients receiving a kidney from a small pediatric donor at our center between 2005 and 2017.

Methods:

The outcome of 47 transplants from SPD were compared with 153 kidney transplants from deceased-standard criteria donors (SCD) occurring during the same time period. Incidence of clinical signs of hyperfiltration injury (eg, proteinuria) was investigated. According to our policy, surveillance biopsies were taken at 3 and 6 months post-transplant and were evaluated in terms of signs of hyperfiltration injury.

Results:

At a median follow-up of 2.3 years post-transplant, death-censored graft survival of SPD was comparable to transplants from SCD (94% vs 93%; P = .54). Furthermore, allograft function at last follow-up (estimated glomerular filtration rate–Modification of Diet in Renal Disease) was significantly higher in pediatric transplant (80 vs 55 ml/min/1.73 m2, P = .002). We found histological signs of early hyperfiltration injury in 55% of SPD. There was an equally low proteinuria in both groups during follow-up.

Limitations:

It is a single center and retrospective observational study with small sample size. The outcomes were investigated in a well-selected population of recipients with low body mass index, low immunological risk, and well-controlled hypertension and was not compared with equal selected group of recipients.

Conclusions:

Early histological and clinical signs of hyperfiltration injury in SPD is frequent. Despite the hyperfiltration injury, there is an equal allograft survival and even superior allograft function in SPD compared with SCD during follow-up. This observation supports the concept of high adaptive capacity of pediatric donor kidneys.

Successful single kidney transplantation from pediatric donors less than or equal to 10 kg to adult recipient: a retrospective cohort study

BACKGROUND

Kidneys from very small pediatric donors (≤10 kg) are underutilized. Compared to en bloc kidney transplantation (EBKT), single kidney transplantation (SKT) can maximize donor resources. However, it remains unknown whether it's appropriate to perform SKTs from donors weighing ≤10 kg.

METHODS

A total of 35 adult recipients undergoing kidney transplantation from donors weighing ≤10 kg at our center from December 2014 to December 2019 were included and grouped into SKT group (n=20) and EBKT group (n=15). Transplant outcomes were retrospectively analyzed and compared between 2 groups.

RESULTS

The 1-year and 3-year death-censored graft survival in SKT group was 95%, it is not significantly higher than that in EBKT group (80%, log-rank test, P=0.38). Significant improvement in estimated glomerular filtration rate (eGFR) was noted in both groups, despite eGFR at 1 year was lower in the SKT group (P<0.01). Proteinuria was common in both groups but subsided gradually during the follow-up time. Complication rates were similar between 2 groups with no vascular thrombosis in the SKT group.

CONCLUSIONS

In conclusion, SKTs from donors weighing ≤10 kg to adult recipients achieves comparable outcomes with EBKTs, which provides evidence to support performing SKTs from donors weighing ≤10 kg in certain donor and recipient scenarios.

Urine Angiotensin II Signature Proteins as Markers of Fibrosis in Kidney Transplant Recipients

BACKGROUND

Interstitial fibrosis/tubular atrophy (IFTA) is an important cause of kidney allograft loss; however, noninvasive markers to identify IFTA or guide antifibrotic therapy are lacking. Using angiotensin II (AngII) as the prototypical inducer of IFTA, we previously identified 83 AngII-regulated proteins in vitro. We developed mass spectrometry-based assays for quantification of 6 AngII signature proteins (bone marrow stromal cell antigen 1, glutamine synthetase [GLNA], laminin subunit beta-2, lysophospholipase I, ras homolog family member B, and thrombospondin-I [TSP1]) and hypothesized that their urine excretion will correlate with IFTA in kidney transplant patients.

METHODS

Urine excretion of 6 AngII-regulated proteins was quantified using selected reaction monitoring and normalized by urine creatinine. Immunohistochemistry was used to assess protein expression of TSP1 and GLNA in kidney biopsies.

RESULTS

The urine excretion rates of AngII-regulated proteins were found to be increased in 15 kidney transplant recipients with IFTA compared with 20 matched controls with no IFTA (mean log2[fmol/µmol of creatinine], bone marrow stromal cell antigen 1: 3.8 versus 3.0, P = 0.03; GLNA: 1.2 versus -0.4, P = 0.03; laminin subunit beta-2: 6.1 versus 5.4, P = 0.06; lysophospholipase I: 2.1 versus 0.6, P = 0.002; ras homolog family member B: 1.2 versus -0.1, P = 0.006; TSP1_GGV: 2.5 versus 1.9; P = 0.15; and TSP1_TIV: 2.0 versus 0.6, P = 0.0006). Receiver operating characteristic curve analysis demonstrated an area under the curve = 0.86 for the ability of urine AngII signature proteins to discriminate IFTA from controls. Urine excretion of AngII signature proteins correlated strongly with chronic IFTA and total inflammation. In a separate cohort of 19 kidney transplant recipients, the urine excretion of these 6 proteins was significantly lower following therapy with AngII inhibitors (P < 0.05).

CONCLUSIONS

AngII-regulated proteins may represent markers of IFTA and guide antifibrotic therapies.

Outcomes of single kidney transplantation from pediatric donors: A single-center experience

Kidneys from pDDs are increasingly used to narrow the huge gap between incremental demand and static supply. However, there is still controversy on the clinical outcome of SKT from pDDs. We conducted a retrospective cohort study of 452 adult recipients in our center between March 2012 and February 2017. Outcomes of 3 groups, transplants with organs from pDDs (n=50), aDDs (n=207), and LDs (n=195), were compared. The mean age and weight of pDDs were 8.98 years (range 8 months-17 years) and 30.05 kg (range 8.2-55 kg), respectively. There was no difference in 1-year (96.0%, 98.1%, and 99.0%, respectively, P=.277) and 3-year patient survival (96.0%, 98.1%, and 99.0%, respectively, P=.277) or in 1-year (96.0%, 96.6%, and 98.5%, P=.307) and 3-year (96.0%, 96.6% and 97.9%, P=.437) graft survival. SCr, eGFR, and allograft size were similar among the 3 groups at 6th month post-transplant and thereafter. Incidence of DGF was higher in patients of the aDD group than those in the pDD group (22.7% vs 10.0%, P<.001), but there was no difference in AR and infection. SKT from pDDs to adult recipients is effective and safe with acceptable outcomes, and it will be a promising expansion to the donor pool.

Effect of renin-angiotensin system inhibitors on survival in kidney transplant recipients: A systematic review and meta-analysis

Renin-angiotensin system inhibitors, specifically angiotensin II converting enzyme inhibitors (ACEI) and angiotensin II receptor blockers (ARB), have confirmed renoprotective benefits in patients with proteinuria and hypertension. However, it remains controversial whether these agents are beneficial to kidney recipients. We conducted this meta-analysis to evaluate the effects of ACEI/ARB treatment on patient and allograft survival after kidney transplant. The PubMed, Embase and Cochrane Library databases were searched for eligible articles from before May 2016, and we included 24 articles (9 randomised controlled trials [RCTs] and 15 cohort studies with 54,096 patients), in which patient or graft survival was compared between an ACEI/ARB treatment arm and a control arm. Pooled results showed that ACEI/ARB was associated with decreased risks of patient death (relative risk [RR] = 0.64; 95% confidence interval [CI]:0.49-0.84) and graft loss (RR = 0.59; 95%CI:0.47-0.74). Subgroup analysis of the cohorts revealed significantly reduced patient death (RR = 0.61; 95%CI:0.50-0.74) and graft loss (RR = 0.58; 95%CI:0.46-0.73), but this was not seen in RCTs (patient survival: RR = 0.84, 95%CI:0.39-1.81; graft survival: RR = 0.70, 95%CI:0.17-2.79). Significantly less graft loss was noted among patients with biopsy-proved chronic allograft nephropathy (CAN) (RR = 0.26, 95%CI:0.16-0.44). Furthermore, the benefit of ACEI/ARB on patient survival (RR = 0.62; 95%CI:0.47-0.83) and graft survival (RR = 0.58, 95%CI:0.47-0.71) was limited to those with ≥3years' follow-up. ACEI/ARB decreased proteinuria (P < 0.001) and lowered haemoglobin (P = 0.002), but the haemoglobin change requires no additional treatment (from 119-131 g/L to 107-123 g/L). We therefore concluded that ACEI/ARB treatment may reduce patient death and graft loss, but additional well-designed prospective studies are needed to validate these findings.

Impact of recipient ACE I/D genotype on kidney function in renal transplant patients: a meta-analysis of cross-sectional and longitudinal studies

Aim: To perform a systematic review and meta-analysis of studies evaluating the influence of recipient angiotensin-converting enzyme insertion/deletion (ACE I/D) polymorphism on kidney function in renal transplant recipients. Materials & methods: A comprehensive search was performed through PubMed, Web of Knowledge and Cochrane databases up to December 2014. The methodological quality of identified studies was assessed using the MINORS criteria. Results: A total of 15 studies evaluating the role of recipient ACE I/D were included in the meta-analysis. In overall analyzes and subsequent subgroup and sensitivity analyzes, no evidence emerged of an effect of ACE I/D on serum creatinine levels, creatinine clearance or glomerular filtration rate. Conclusion: Although further investigation is still needed to determine the role of donor ACE genotype, recipient ACE I/D does not play a significant role on kidney function in renal transplant patients.