Minimal proteinuria one year after transplant is a risk factor for graft survival in kidney transplantation

Contemporary Biomarkers for Renal Transplantation: A Narrative Overview

Renal transplantation (RT) is the preferred treatment for end-stage renal disease. However, clinical challenges persist, i.e., early detection of graft dysfunction, timely identification of rejection episodes, personalization of immunosuppressive therapy, and prediction of long-term graft survival. Biomarkers have emerged as valuable tools to address these challenges and revolutionize RT patient care. Our review synthesizes the existing scientific literature to highlight promising biomarkers, their biological characteristics, and their potential roles in enhancing clinical decision-making and patient outcomes. Emerging non-invasive biomarkers seemingly provide valuable insights into the immunopathology of nephron injury and allograft rejection. Moreover, we analyzed biomarkers with intra-nephron specificities, i.e., glomerular vs. tubular (proximal vs. distal), which can localize an injury in different nephron areas. Additionally, this paper provides a comprehensive analysis of the potential clinical applications of biomarkers in the prediction, detection, differential diagnosis and assessment of post-RT non-surgical allograft complications. Lastly, we focus on the pursuit of immune tolerance biomarkers, which aims to reclassify transplant recipients based on immune risk thresholds, guide personalized immunosuppression strategies, and ultimately identify patients for whom immunosuppression may safely be reduced. Further research, validation, standardization, and prospective studies are necessary to fully harness the clinical utility of RT biomarkers and guide the development of targeted therapies.

Melatonin in preservation solutions prevents ischemic injury in rat kidneys

Transplantation is lifesaving and the most effective treatment for end-stage organ failure. The transplantation success depends on the functional preservation of organs prior to transplantation. Currently, the University of Wisconsin (UW) and histidine-tryptophan-ketoglutarate (HTK) are the most commonly used preservation solutions. Despite intensive efforts, the functional preservation of solid organs prior to transplantation is limited to hours. In this study, we modified the UW solution containing components from both the UW and HTK solutions and analyzed their tissue-protective effect against ischemic injury. The composition of the UW solution was changed by reducing hydroxyethyl starch concentration and adding Histidine/Histidine-HCl which is the main component of HTK solution. Additionally, the preservation solutions were supplemented with melatonin and glucosamine. The protective effects of the preservation solutions were assessed by biochemical and microscopical analysis at 2, 10, 24, and 72 h after preserving the rat kidneys with static cold storage. Lactate dehydrogenase (LDH) activity in preservation solutions was measured at 2, 10, 24, and 72. It was not detectable at 2 h of preservation in all groups and 10 h of preservation in modified UW+melatonin (mUW-m) and modified UW+glucosamine (mUW-g) groups. At the 72nd hour, the lowest LDH activity (0.91 IU/g (0.63–1.17)) was measured in the mUW-m group. In comparison to the UW group, histopathological damage score was low in modified UW (mUW), mUW-m, and mUW-g groups at 10, 24, and 72 hours. The mUW-m solution at low temperature was an effective and suitable solution to protect renal tissue for up to 72 h.

Treatment of chronic active T cell-mediated rejection after kidney transplantation: A retrospective cohort study of 37 transplants

AIM

Data on the treatment of chronic active T cell-mediated rejection (CA-TCMR) are scarce, and therapeutical strategies for CA-TCMR have not been established. We retrospectively evaluated the outcomes and effects of treatment on pathological and clinical findings in patients with CA-TCMR.

METHODS

This study comprised 37 patients who underwent kidney transplantation at our institute who were diagnosed with CA-TCMR between January 2018 and December 2020. Patients were followed until October 2021.

RESULTS

Thirty-two of the 37 patients were treated. During the observation period, two patients died (5%), and five patients developed allograft loss (13%). A univariate Cox proportional hazards model showed that indication biopsy, higher spot urine protein/creatinine ratio (UPCR), and Banff ci/ct scores were risk factors for allograft loss. Of the treated patients, 23 underwent follow-up biopsies. The Wilcoxon signed-rank test showed significant improvement in the Baff scores for "ti", "i-IFTA", "t", and "t-IFTA" after treatment. On pathology, 13 (57%) of the patients who underwent follow-up biopsy improved to "no evidence of rejection" or "borderline change". Assuming that improvement in pathology to "borderline change" or "no evidence of rejection" on follow-up biopsy indicates response to treatment, multivariate logistic analysis showed that lower UPCR was a predictive factor for response to treatment. No specific effect of treatment type was observed.

CONCLUSIONS

Our results indicate that treatment could improve the pathological findings in CA-TCMR. This article is protected by copyright. All rights reserved.

Time-Varying Covariates and Risk Factors for Graft Loss in Kidney Transplantation

OBJECTIVES

The present study was designed to evaluate the factors involved in long-term graft survival in recipients of kidney transplantation.

MATERIALS AND METHODS

We reviewed 755 Iranian adult recipients who underwent kidney transplantation at Shahid Labbafinejad Medical Center in Tehran, Iran. Patients were followed for 5 years after transplantation. The primary outcome was the time between transplantation and graft loss. Using Cox regression, we studied the effect of time-independent variables (recipients' age and sex, donors' age, and type of donor), time-dependent covariates (body mass index [BMI], systolic blood pressure, diastolic blood pressure, high-density lipoprotein (HDL) and low-density lipoprotein (LDL) cholesterol levels, proteinuria and serum creatinine level), and immunosuppressive drugs on graft loss 60 months after transplantation. The results are presented as the hazard ratio (HR) with 95% confidence intervals.

RESULTS

Result from Cox proportional hazards model showed that the HR of graft loss was 1.62 (95% CI: 1.03-2.54) in cadaveric donor compared with living donor kidney recipients. The HR of graft loss for recipient age was 1.02 (95% CI: 1.002-1.030). Moreover, according to obtained results, the risk of losing functional transplant increased for each mg/dL rise in serum creatinine at least 9% and at most 40%. Our results also showed that 1 unit increase of BMI has at least a 2% and at most a 15% decremented effect on the hazard ratio of graft loss.

CONCLUSIONS

Having lower levels of creatinine and receiving a kidney from a younger living donor were associated with a decreased risk of graft loss. Graft loss is more likely to occur in patients with lower BMI.

Effect of earlier-proteinuria on graft functions after one-year living donor renal transplantation

BACKGROUND

Proteinuria is an indicator of subsequent renal function decline in most nephropathies and early proteinuria has been assumed to be a risk factor of poor kidney transplant outcomes. However, there is no information about the effect of earlier-proteinuria at the first week on short-term graft function after living donor renal transplantation.

METHODS

Retrospective cohort study of 439 living donor kidney transplants to analyze the effect of early proteinuria at 7-day post-transplantation on short-term prognosis of living donor renal transplantation. Patients were stratified into 2 groups according to the definition of earlier-proteinuria: Group A as proteinuria < 0.4 g/24h and Group B as proteinuria ≥ 0.4 g/24h, and differences over the first year post-transplantation were analyzed.

RESULTS

Patients with earlier-proteinuria ≥ 0.4 g/24h had a significantly higher 1-year proteinuria and lower 1-year graft function post-transplantation. Discrepancies of weight ratio of donor-recipient and mean artery pressure difference of recipient to donor influenced the urine protein excretion at the 7-day post-transplantation.

CONCLUSIONS

Earlier-proteinuria at 7-day after living donor renal transplantation was associated with short-term graft function. To eliminate the functional discrepancies between living donors and recipients could be viewed as a solution of reducing earlier-proteinuria.

Derivation of a Predictive Model for Graft Loss Following Acute Kidney Injury in Kidney Transplant Recipients

Background:

Acute kidney injury (AKI) is common in the kidney transplant population.

Objective:

To derive a multivariable survival model that predicts time to graft loss following AKI.

Design:

Retrospective cohort study using health care administrative and laboratory databases.

Setting:

Southwestern Ontario (1999-2013) and Ottawa, Ontario, Canada (1996-2013).

Patients:

We included first-time kidney only transplant recipients who had a hospitalization with AKI 6 months or greater following transplant.

Measurements:

AKI was defined using the Acute Kidney Injury Network criteria (stage 1 or greater). The first episode of AKI was included in the analysis. Graft loss was defined by return to dialysis or repeat kidney transplant.

Methods:

We performed a competing risk survival regression analysis using the Fine and Gray method and modified the model into a simple point system. Graft loss with death as a competing event was the primary outcome of interest.

Results:

A total of 315 kidney transplant recipients who had a hospitalization with AKI 6 months or greater following transplant were included. The median (interquartile range) follow-up time was 6.7 (3.3-10.3) years. Graft loss occurred in 27.6% of the cohort. The final model included 6 variables associated with an increased risk of graft loss: younger age, increased severity of AKI, failure to recover from AKI, lower baseline estimated glomerular filtration rate, increased time from kidney transplant to AKI admission, and receipt of a kidney from a deceased donor. The risk score had a concordance probability of 0.75 (95% confidence interval [CI], 0.69-0.82). The predicted 5-year risk of graft loss fell within the 95% CI of the observed risk more than 95% of the time.

Limitations:

The CIs of the estimates were wide, and model overfitting is possible due to the limited sample size; the risk score requires validation to determine its clinical utility.

Conclusions:

Our prognostic risk score uses commonly available information to predict the risk of graft loss in kidney transplant patients hospitalized with AKI. If validated, this predictive model will allow clinicians to identify high-risk patients who may benefit from closer follow-up or targeted enrollment in future intervention trials designed to improve outcomes.

Proteinuria 1 year after renal transplantation is associated with impaired graft survival in children

BACKGROUND

Proteinuria is a common manifestation of chronic kidney disease (CKD), and there is a high incidence of CDK and its complications following renal transplantation. However, little data are available on the association between proteinuria and graft/patient survival in the paediatric transplant population. The primary aim of this study was to investigate the associations between posttransplant proteinuria and graft/patient survival in children after renal transplantation.

METHODS

In this retrospective study, we screened all 91 children receiving renal allografts at a single institution between 1997 and 2007. The inclusion criteria were a functioning graft at 1 year posttransplant, data availability and no recurrence of focal-segmental glomerulosclerosis. The final cohort included 75 patients. Proteinuria was considered to be pathologic if the urinary protein/creatinine ratio was >30 mg/mmol. Donor and recipient characteristics, data on proteinuria, estimated glomerular filtration rate (eGFR) and rejection episodes were analysed. The most recent of the biopsies performed during the follow-up after 1 year posttransplant were analysed separately in the proteinuric group and the non-proteinuric group.

RESULTS

Proteinuria at 1-year posttransplant was pathologic in 35 % of patients. The 5-year graft survival rate was significantly lower in the proteinuric group than in the non-proteinuric group (77 vs. 100 %; p < 0.001). Proteinuria at 1 year posttransplant was associated with reduced long-term graft survival independent of other risk factors, including decreased eGFR or episodes of acute corticosensitive and corticoresistant rejection. The most frequent histologic finding in the proteinuric group was chronic rejection. There was no significant difference in the 5-year patient survival rate between the proteinuric group and the non-proteinuric group.

CONCLUSION

This study emphasizes the importance of proteinuria as a prognostic factor of renal allograft survival in children.

Management of proteinuria in the transplanted patient

Proteinuria is a relatively frequent complication in children after renal transplantation (40-80 %). It is usually mild and non-nephrotic in nature and predominantly tubular in origin. The major causes of post-transplant proteinuria are recurrence of primary glomerulonephritis [mostly focal segmental glomerulosclerosis (FSGS)], rejection (acute and chronic), mTOR inhibitors or hypertension. Proteinuria is a risk factor for graft loss and patient death in adults, and even a mild proteinuria (0.1-0.2 g/day) is associated with impaired graft and patient survival. In children, proteinuria seems to be associated with graft but not patient survival. Proteinuria (protein/creatinine ratio) should be assessed regularly in all children. In children with prior chronic kidney disease due to idiopathic FSGS, proteinuria should be assessed daily during the first month after transplantation to enable early diagnosis of recurrence. The cause of proteinuria should be identified, and graft biopsy should be considered in children with unexplained proteinuria, especially with new onset proteinuria or deterioration of previously mild proteinuria. Treatment must be primarily targeted at the cause of proteinuria, and in normotensive children symptomatic antiproteinuric therapy with angiotensin-converting enzyme inhibitors/angiotensin II receptor antagonists should also be initiated. Other antihypertensive drugs should be used to achieve target blood pressure of <75th percentile. Target proteinuria should be <20 mg/mmol creatinine.

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.

Improved gastrointestinal symptoms and quality of life after conversion from mycophenolate mofetil to enteric-coated mycophenolate sodium in renal transplant patients receiving tacrolimus

It is reported that a conversion from mycophenolate mofetil (MMF) to enteric-coated mycophenolate sodium (EC-MPS) relieves gastrointestinal (GI) symptom burden and improves health-related quality of life (HRQoL). However, it is unclear whether renal transplant recipients using tacrolimus receive the same benefit from the conversion. In this prospective, multi-center, open-label trial, patients were categorized into two groups by their GI symptom screening. Equimolar EC-MPS (n=175) was prescribed for patients with GI burdens; those with no complaints remained on MMF (n=83). Gastrointestinal Symptom Rating Scale (GSRS) and Gastrointestinal Quality of Life Index (GIQLI) were evaluated at baseline and after one month. Patients and physicians completed Overall Treatment Effect (OTE) at one month. EC-MPS-converted patients had worse GSRS and GIQLI scores at baseline than MMF-continued patients (all P<0.001). Significant improvements in GSRS and GIQLI scores were observed for EC-MPS-converted patients at one month, but MMF-continued patients showed worsened GSRS scores (all P<0.05). OTE scale indicated that EC-MPS patients improved in overall GI symptoms and HRQoL more than MMF patients did (P<0.001). In tacrolimus-treated renal transplant recipients with GI burdens, a conversion from MMF to EC-MPS improves GI-related symptoms and HRQoL.