Benefits and risks of protocol biopsies in pediatric renal transplantation

Detection of Subclinical Rejection in Pediatric Kidney Transplantation: Current and Future Practices

INTRODUCTION

The successes in the field of pediatric kidney transplantation over the past 60 years have been extraordinary. Year over year, there have been significant improvements in short-term graft survival. However, improvements in longer-term outcomes have been much less apparent. One important contributor has been the phenomenon of low-level rejection in the absence of clinical manifestations-so-called subclinical rejection (SCR).

METHODS

Traditionally, rejection has been diagnosed by changes in clinical parameters, including but not limited to serum creatinine and proteinuria. This review examines the shortcomings of this approach, the effects of SCR on kidney allograft outcome, the benefits and drawbacks of surveillance biopsies to identify SCR, and new urine and blood biomarkers that define the presence or absence of SCR.

RESULTS

Serum creatinine is an unreliable index of SCR. Surveillance biopsies are the method most utilized to detect SCR. However, these have significant drawbacks. New biomarkers show promise. These biomarkers include blood gene expression profiles and donor derived-cell free DNA; urine gene expression profiles; urinary cytokines, chemokines, and metabolomics; and other promising blood and urine tests.

CONCLUSION

Specific emphasis is placed on studies carried out in pediatric kidney transplant recipients.

TRIAL REGISTRATION

ClinicalTrials.gov: NCT03719339.

Unveiling systemic responses in kidney transplantation: interplay between the allograft transcriptome and serum proteins

Immunity, as defined by systems biology, encompasses a holistic response throughout the body, characterized by intricate connections with various tissues and compartments. However, this concept has been rarely explored in kidney transplantation. In this proof-of-concept study, we investigated a direct association between the allograft phenotype and serum protein signatures. Time-matched samples of graft biopsies and blood serum were collected in a heterogeneous cohort of kidney-transplanted patients (n = 15) for bulk RNA sequencing and proteomics, respectively. RNA transcripts exhibit distinct and reproducible, coregulated gene networks with specific functional profiles. We measured 159 serum proteins and investigated correlations with gene expression networks. Two opposing axes-one related to metabolism and the other to inflammation-were identified. They may represent a biological continuum between the allograft and the serum and correlate with allograft function, but not with interstitial fibrosis or proteinuria. For signature validation, we used two independent proteomic data sets (n = 21). Our findings establish a biological link between the allograft transcriptome and the blood serum proteome, highlighting systemic immune effects in kidney transplantation and offering a promising framework for developing allograft-linked biomarkers.

Non-invasive biomarkers of acute rejection in pediatric kidney transplantation: New targets and strategies

Kidney transplantation is the preferred treatment for pediatric end-stage renal disease. However, pediatric recipients face unique challenges due to their prolonged need for kidney function to accommodate growth and development. The continual changes in the immune microenvironment during childhood development and the heightened risk of complications from long-term use of immunosuppressive drugs. The overwhelming majority of children may require more than one kidney transplant in their lifetime. Acute rejection (AR) stands as the primary cause of kidney transplant failure in children. While pathologic biopsy remains the "gold standard" for diagnosing renal rejection, its invasive nature raises concerns regarding potential functional impairment and the psychological impact on children due to repeated procedures. In this review, we outline the current research status of novel biomarkers associated with AR in urine and blood after pediatric kidney transplantation. These biomarkers exhibit superior diagnostic and prognostic performance compared to conventional ones, with the added advantages of being less invasive and highly reproducible for long-term graft monitoring. We also integrate the limitations of these novel biomarkers and propose a refined monitoring model to optimize the management of AR in pediatric kidney transplantation.

Pediatric Transplant Interventions

The field of pediatric organ transplantation has grown significantly in recent decades, with interventional radiology (IR) playing an essential role in managing pre and post-transplant complications. Pediatric transplant patients face unique challenges compared to adults, including donor-recipient size mismatch, and complications of a growing child with changing physiology. Interventional radiologists play a major role in pediatric renal and liver transplant. IR interventions begin early in the child's pretransplant journey, with diagnostic procedures such as biopsies, angiograms, and cholangiograms. These procedures are essential for understanding the etiology of organ failure and identifying potential transplant candidates. Minimally invasive therapeutic procedures may serve as bridges to transplant and may include vascular access optimization for hemodialysis, transjugular intrahepatic portosystemic shunts (TIPS) creation, and tumor embolization or ablation. After transplant, image-guided biopsies for the surveillance of graft rejection and treatment of vascular or luminal stenoses, pseudoaneurysms, and anastomotic leaks can maintain the function and longevity of the transplant organ. Careful consideration must be given to patient size and evolving anatomy, radiation exposure, and the need for deeper sedation for pediatric patients. Despite these challenges, the integration of IR in pediatric transplant care has proven beneficial, offering minimally invasive alternatives to surgery, faster recovery times, and improved outcomes.

Rejection markers in kidney transplantation: do new technologies help children?

Recent insights in allorecognition and graft rejection mechanisms revealed a more complex picture than originally considered, involving multiple pathways of both adaptive and innate immune response, supplied by efficient inflammatory synergies. Current pillars of transplant monitoring are serum creatinine, proteinuria, and drug blood levels, which are considered as traditional markers, due to consolidated experience, low cost, and widespread availability. The most diffuse immunological biomarkers are donor-specific antibodies, which are included in routine post-transplant monitoring in many centers, although with some reproducibility issues and interpretation difficulties. Confirmed abnormalities in these traditional biomarkers raise the suspicion for rejection and guide the indication for graft biopsy, which is still considered the gold standard for rejection monitoring. Rapidly evolving new "omic" technologies have led to the identification of several novel biomarkers, which may change the landscape of transplant monitoring should their potential be confirmed. Among them, urinary chemokines and measurement of cell-free DNA of donor origin are perhaps the most promising. However, at the moment, these approaches remain highly expensive and cost-prohibitive in most settings, with limited clinical applicability; approachable costs upon technology investments would speed their integration. In addition, transcriptomics, metabolomics, proteomics, and the study of blood and urinary extracellular vesicles have the potential for early identification of subclinical rejection with high sensitivity and specificity, good reproducibility, and for gaining predictive value in an affordable cost setting. In the near future, information derived from these new biomarkers is expected to integrate traditional tools in routine use, allowing identification of rejection prior to clinical manifestations and timely therapeutic intervention. This review will discuss traditional, novel, and invasive and non-invasive biomarkers, underlining their strengths, limitations, and present or future applications in children.

Non-traditional risk factors of progression of chronic kidney disease in adult population: a scoping review

Chronic kidney disease (CKD) has become a public health concern over the last several years. Nowadays developed countries spend around 3% of their annual health-care budget on patients with CKD. According to the scientific community the most remarkable risk factors for CKD are diabetes and hypertension. Unknown CKD etiology has been reported as a global phenomenon including uncommon risk factors such as: dehydration, leptospirosis, heat stress, water quality, and others. This study aims to report non-traditional risk factors for ESRD based on a scoping review methodology. The scoping review methodology described by Arksey and O'Malley was used by performing an extensive review of the information. A total of 46 manuscripts were reviewed. The non-traditional ESRD risk factors are depicted based on six categories. Gender and ethnicity have been considered as risk factors for ESRD. Erythematous systemic lupus (ESL) is reported as an important risk factor for ESRD. Pesticide use has been an significant risk factor due to its effects on human and environmental health. Some compounds commonly used in homes against insects and plants are related to ESRD. Congenital and hereditary diseases in the urinary tract have been studied as a cause of ESRD in children and young adults. End-stage renal disease is a major concern for public health on a global level. As it can be seen, non-traditional risk factors are several and have different etiologies. It is necessary to put the issue on the table and add it to the public agenda in order to find multidisciplinary solutions.

Molecular HLA mismatching for prediction of primary humoral alloimmunity and graft function deterioration in paediatric kidney transplantation

Introduction

Rejection remains the main cause of allograft failure in paediatric kidney transplantation and is driven by donor-recipient HLA mismatching. Modern computational algorithms enable assessment of HLA mismatch immunogenicity at the molecular level (molecular-mismatch, molMM). Whilst molMM has been shown to correlate with alloimmune outcomes, evidence demonstrating improved prediction performance against traditional antigen mismatching (antMM) is lacking.

Methods

We analysed 177 patients from the CERTAIN registry (median follow-up 4.5 years). molMM scores included Amino-Acid-Mismatch-Score (AAMS), Electrostatic-Mismatch-Score (EMS3D) and netMHCIIpan (netMHC1k: peptide binding affinity ≤1000 nM; netMHC: binding affinity ≤500 nM plus rank <2%). We stratified patients into high/low-risk groups based on risk models of DSA development.

Results

Donor-specific HLA antibodies (DSA) predominantly targeted the highest scoring molMM donor antigen within each HLA locus. MolMM scores offered superior discrimination versus antMM in predicting de novo DSA for all HLA loci; the EMS3D algorithm had particularly consistent performance (area under the receiver operating characteristic curve (AUC) >0.7 for all HLA loci vs. 0.52-0.70 for antMM). ABMR (but not TCMR) was associated with HLA-DQ molMM scores (AAMS, EMS3D and netMHC). Patients with high-risk HLA-DQ molMM had increased risk of graft function deterioration (50% reduction in baseline eGFR (eGFR50), adjusted HR: 3.5, 95% CI 1.6-8.2 high vs. low EMS3D). Multivariable modelling of the eGFR50 outcome using EMS3D HLA-DQ stratification showed better discrimination (AUC EMS3D vs. antMM at 2 years: 0.81 vs. 0.77, at 4.5 years: 0.72 vs. 0.64) and stratified more patients into the low-risk group, compared to traditional antMM.

Conclusion

Molecular mismatching was superior to antigen mismatching in predicting humoral alloimmunity. Molecular HLA-DQ mismatching appears to be a significant prognostic factor for graft function deterioration in paediatric kidney transplantation.

Pearls and Pitfalls in Pediatric Kidney Transplantation After 5 Decades

Worldwide, over 1,300 pediatric kidney transplantations are performed every year. Since the first transplantation in 1959, healthcare has evolved dramatically. Pre-emptive transplantations with grafts from living donors have become more common. Despite a subsequent improvement in graft survival, there are still challenges to face. This study attempts to summarize how our understanding of pediatric kidney transplantation has developed and improved since its beginnings, whilst also highlighting those areas where future research should concentrate in order to help resolve as yet unanswered questions. Existing literature was compared to our own data of 411 single-center pediatric kidney transplantations between 1968 and 2020, in order to find discrepancies and allow identification of future challenges. Important issues for future care are innovations in immunosuppressive medication, improving medication adherence, careful donor selection with regard to characteristics of both donor and recipient, improvement of surgical techniques and increased attention for lower urinary tract dysfunction and voiding behavior in all patients.

Percutaneous Core Needle Biopsy: Considerations in the Pediatric Patient

Image-guided percutaneous biopsy is the cornerstone of solid tissue diagnosis. The ability to safely sample tissue in locations that previously required surgery or necessitated empiric therapy has allowed for more personalized treatment options, as well as more rapid development of novel therapeutics. In children, these same advantages are accompanied by a smaller margin for error and rapidly expanding indications. The intent of this review is to outline the role of image-guided biopsy in the management of childhood disease, how this role is changing, and the practical aspects of managing and performing pediatric biopsies.

Experience of the first 6 years of pediatric kidney transplantation in Indonesia: A multicenter retrospective study

BACKGROUND

Pediatric kidney transplantation was only introduced in Indonesia in 2013. We therefore aimed to assess the characteristics and outcomes of transplants performed from its inception to January 2019.

METHOD

The study had a dual-center retrospective design. We examined the records of kidney transplant recipients and then calculated patient and graft survival rates by Kaplan-Meier survival analysis with 95% confidence intervals (95% CI).

RESULTS

In total, 12 kidney transplantations were performed in eleven children during the study period; among these, ten were boys, and nine had renal failure caused by congenital anomaly of the kidney or urinary tract. All donors were living, and all recipients were on dialysis at the time of transplantation, when their median age was 14.5 years (range, 8-19 years). Three patients died of infection in the first year of follow-up and two lost their allograft by the time of their last follow-up (median, 13 months; range, 4-69 months). The 1-year patient survival rate was therefore 68.18% (95% CI, 29.72%-88.61%), which remained unchanged at 3 and 5 years. However, the non-death-censored graft survival rates at 1, 3, and 5 years were 68.18% (95% CI, 29.72%-88.61%), 51.14% (95% CI, 14.5%-79.46%), and 25.57% (95% CI, 1.38%-64.78%), respectively.

CONCLUSION

Patient and graft survival rates after pediatric kidney transplantation in Indonesia are lower than those reported in other countries. Closer patient follow-up and stricter adherence to guidelines could improve transplant outcomes, but we must seek to improve the balance between infection and rejection.

Characterizing the frequency of modifiable histological changes observed on surveillance biopsies in pediatric kidney allograft recipients

BACKGROUND

Rejection is responsible for just under 50% of graft loss in the pediatric kidney transplant population. Early identification and treatment of allograft injury, specifically modifiable pathologies such as subclinical rejection (SCR), calcineurin inhibitor toxicity, and BK virus nephropathy, may improve allograft survival. Protocol surveillance biopsy (SB) currently offers the earliest opportunity for targeted interventions.

METHODS

This is a single-center retrospective review of 215 kidney SBs obtained from 2008 to 2016 in 97 pediatric kidney transplant recipients. SBs were obtained at 6, 12, and 24 months post-transplantation. Frequency of abnormal histologic findings, estimated glomerular filtration rate at time of SB, and SB-related complications were recorded. Data were analyzed to investigate possible time trends and the presence of demographic or clinical associations with abnormal histologic findings.

RESULTS

Potentially modifiable histologic findings were seen in 38.1% of all SBs. SCR was found with increasing frequency across all time points with an estimated 49% increase in the odds of a SCR finding per additional 6 months post-transplantation (aOR 1.49, 95% CI 1.06-2.09, p = 0.022). Among follow-up biopsies in patients who underwent treatment for SCR, 50% had no SCR and 18.8% showed histologic improvement. The complication rate associated with SB was 1.9% (4/215 SBs) and consisted of only minor complications.

CONCLUSIONS

SBs are safe and offer the opportunity to identify and treat modifiable histologic changes in the pediatric kidney transplant population. The performance of SBs for up to 2 years after transplantation can have meaningful clinical impact.

The role of protocol biopsies after pediatric kidney transplantation

Data on protocol biopsies (PBs) after pediatric kidney transplantation are rare.We evaluated 6-month post-transplantation renal function in 86 children after PB as observational study. Patients were divided into 3 groups:Glomerular filtration rate (GFR) and delta GFR were determined.PBs 6 months post-kidney transplantation did not influence the clinical course in stable pediatric patients and are therefore of questionable value. Decreased kidney function may however be stabilized by therapeutic intervention according to results of PB.

When does vesicoureteral reflux in pediatric kidney transplant patients need treatment?

PURPOSE

The treatment of VUR in children with UTI has changed significantly, due to studies showing that antibiotic prophylaxis does not decrease renal scarring. As children with kidney transplants are at higher risk for UTI, we investigated if select patients with renal transplant VUR could be managed without surgery.

MATERIALS AND METHODS

A total of 18 patients with VUR into their renal grafts were identified, and 319 patients underwent transplantation from 2006 to 2016. The cause for the detection of the VUR, treatment, and graft function was reviewed.

RESULTS

Six boys and 12 girls were identified, 13 of whom had grade 3 or 4 VUR into the renal graft. Nine patients presented with hydronephrosis or abnormal renal biopsy: eight were successfully managed with antibiotic prophylaxis and bladder training, one developed UTI and underwent Dx/HA subureteric injection. Nine patients presented with recurrent febrile UTI, only one was successfully managed without surgery. Only 2 of 9 (22%) patients who underwent Dx/HA injection had resolution of their reflux. Of the remaining seven, five required open ureteral reimplantation (two for obstruction), one lost the graft due to rejection, and one had significant hydronephrosis. eGFR was similar between the hydronephrosis, UTI, and abnormal renal biopsy groups at all times.

CONCLUSION

Patients with transplant VUR and recurrent febrile UTI are more likely to require surgical therapy, but the complication and failure rate for Dx/HA injection is significant. Patients with transplant VUR without febrile UTI can be successfully managed with bladder training and temporary antibiotic prophylaxis.