Proteinuria: a new marker of long-term graft and patient survival in kidney transplantation

Amiloride evokes significant natriuresis and weight loss in kidney transplant recipients with and without albuminuria

Albuminuria in kidney transplant recipients (KTRs) is associated with hypertension and aberrant glomerular filtration of serine proteases that may proteolytically activate the epithelial Na+ channel (ENaC). The present nonrandomized, pharmacodynamic intervention study aimed to investigate if inhibition of ENaC increases Na+ excretion and reduces extracellular volume in KTRs dependent on the presence of albuminuria. KTRs with and without albuminuria (albumin-to-creatinine ratio > 300 mg/g, n = 7, and <30 mg/g, n = 7, respectively) were included and ingested a diet with fixed Na+ content (150 mmol/day) for 5 days. On the last day, amiloride at 10 mg was administered twice. Body weight, 24-h urine electrolyte excretion, body water content, and ambulatory blood pressure as well as plasma renin, angiotensin II, and aldosterone concentrations were determined before and after amiloride. Amiloride led to a significant decrease in body weight, increase in 24-h urinary Na+ excretion, and decrease in 24-h urinary K+ excretion in both groups. Urine output increased in the nonalbuminuric group only. There was no change in plasma renin, aldosterone, and angiotensin II concentrations after amiloride, whereas a significant decrease in nocturnal systolic blood pressure and increase in 24-h urine aldosterone excretion was observed in albuminuric KTRs only. There was a significant correlation between 24-h urinary albumin excretion and amiloride-induced 24-h urinary Na+ excretion. In conclusion, ENaC activity contributes to Na+ and water retention in KTRs with and without albuminuria. ENaC is a relevant pharmacological target in KTRs; however, larger and long-term studies are needed to evaluate whether the magnitude of this effect depends on the presence of albuminuria.NEW & NOTEWORTHY Amiloride has a significant natriuretic effect in kidney transplant recipients (KTRs) that relates to urinary albumin excretion. The epithelial Na+ channel may be a relevant direct pharmacological target to counter Na+ retention and hypertension in KTRs. Epithelial Na+ channel blockers should be further investigated as a mean to mitigate Na+ and water retention and to potentially obtain optimal blood pressure control in KTRs.

Sodium-glucose cotransporter-2 inhibitor therapy in kidney transplant patients with type 2 or post-transplant diabetes: an observational multicentre study

BACKGROUND

Sodium-glucose cotransporter-2 inhibitors (SGLT2is) have cardioprotective and renoprotective effects. However, experience with SGLT2is in diabetic kidney transplant recipients (DKTRs) is limited.

METHODS

This observational multicentre study was designed to examine the efficacy and safety of SGLT2is in DKTRs. The primary outcome was adverse effects within 6 months of SGLT2i treatment.

RESULTS

Among 339 treated DKTRs, adverse effects were recorded in 26%, the most frequent (14%) being urinary tract infection (UTI). In 10%, SGLT2is were suspended mostly because of UTI. Risk factors for developing a UTI were a prior episode of UTI in the 6 months leading up to SGLT2i use {odds ratio [OR] 7.90 [confidence interval (CI) 3.63-17.21]} and female sex [OR 2.46 (CI 1.19-5.03)]. In a post hoc subgroup analysis, the incidence of UTI emerged as similar in DKTRs treated with SGLT2i for 12 months versus non-DKTRs (17.9% versus 16.7%). Between baseline and 6 months, significant reductions were observed in body weight [-2.22 kg (95% CI -2.79 to -1.65)], blood pressure, fasting glycaemia, haemoglobin A1c [-0.36% (95% CI -0.51 to -0.21)], serum uric acid [-0.44 mg/dl (95% CI -0.60 to -0.28)] and urinary protein:creatinine ratio, while serum magnesium [+0.15 mg/dl (95% CI 0.11-0.18)] and haemoglobin levels rose [+0.44 g/dl (95% CI 0.28-0.58]. These outcomes persisted in participants followed over 12 months of treatment.

CONCLUSIONS

SGLT2is in kidney transplant offer benefits in terms of controlling glycaemia, weight, blood pressure, anaemia, proteinuria and serum uric acid and magnesium. UTI was the most frequent adverse effect. According to our findings, these agents should be prescribed with caution in female DKTRs and those with a history of UTI.

Hypertension in kidney transplant recipients

Kidney transplantation is considered the treatment of choice for end-stage kidney disease patients. However, the residual cardiovascular risk remains significantly higher in kidney transplant recipients (KTRs) than in the general population. Hypertension is highly prevalent in KTRs and represents a major modifiable risk factor associated with adverse cardiovascular outcomes and reduced patient and graft survival. Proper definition of hypertension and recognition of special phenotypes and abnormal diurnal blood pressure (BP) patterns is crucial for adequate BP control. Misclassification by office BP is commonly encountered in these patients, and a high proportion of masked and uncontrolled hypertension, as well as of white-coat hypertension, has been revealed in these patients with the use of ambulatory BP monitoring. The pathophysiology of hypertension in KTRs is multifactorial, involving traditional risk factors, factors related to chronic kidney disease and factors related to the transplantation procedure. In the absence of evidence from large-scale randomized controlled trials in this population, BP targets for hypertension management in KTR have been extrapolated from chronic kidney disease populations. The most recent Kidney Disease Improving Global Outcomes 2021 guidelines recommend lowering BP to less than 130/80 mmHg using standardized BP office measurements. Dihydropyridine calcium channel blockers and angiotensin-converting enzyme inhibitors/angiotensin-II receptor blockers have been established as the preferred first-line agents, on the basis of emphasis placed on their favorable outcomes on graft survival. The aim of this review is to provide previous and recent evidence on prevalence, accurate diagnosis, pathophysiology and treatment of hypertension in KTRs.

Association Between a TLR2 Gene Polymorphism (rs3804099) and Proteinuria in Kidney Transplantation Recipients

Background: The occurrence of proteinuria is one of the evaluation indicators of transplanted kidney damage and becomes an independent risk factor for poor prognosis after kidney transplantation. Our research sought to understand these potential associations and detect the underlying impact of single-nucleotide polymorphisms (SNPs) on proteinuria in kidney transplant recipients.

Materials and Methods: There were 200 recipients enrolled in this study, from which blood samples were extracted for SNP mutation–related gene detection. RNA sequencing was performed in kidney tissues after kidney transplantation, and the significantly differentially expressed genes (DEGs) were analyzed between the control group and the proteinuria group. Then, the intersection of genes with SNP mutations and DEGs was conducted to obtain the target genes. Multiple genetic models were used to investigate the relationship between SNPs and proteinuria. In addition, the effect of SNP mutation in the target gene was further validated in human renal podocytes.

Results: According to the sequencing results, 26 significant SNP mutated genes and 532 DEGs were found associated with proteinuria after kidney transplantation. The intersection of SNP mutated genes and DEGs showed that the Toll-like receptor 2 (TLR2) gene was significantly increased in the transplanted renal tissues of patients with proteinuria after kidney transplantation, which was consistent with the results of immunohistochemical staining. Further inheritance model results confirmed that mutations at rs3804099 of the TLR2 gene had significant influence on the occurrence of proteinuria after kidney transplantation. In the in vitro validation, we found that, after the mutation of rs3804099 on the TLR2 gene, the protein expressions of podocalyxin and nephrin in podocytes were significantly decreased, while the protein expressions of desmin and apoptosis markers were significantly increased. The results of flow cytometry also showed that the mutation of rs3804099 on the TLR2 gene significantly increased the apoptotic rate of podocytes.

Conclusion: Our study suggested that the mutation of rs3804099 on the TLR2 gene was significantly related to the generation of proteinuria after kidney transplantation. Our data provide insights into the prediction of proteinuria and may imply potential individualized therapy for patients after kidney transplantation.

First and second morning spot urine protein measurements for the assessment of proteinuria: a diagnostic accuracy study in kidney transplant recipients

BACKGROUND

Quantification of proteinuria in kidney transplant recipients is important for diagnostic and prognostic purposes. Apart from correlation tests, there have been few evaluations of spot urine protein measurements in kidney transplantation.

METHODS

In this cross-sectional study involving 151 transplanted patients, we investigated measures of agreement (bias and accuracy) between the estimated protein excretion rate (ePER), determined from the protein-to-creatinine ratio in the first and second morning urine, and 24-h proteinuria and studied their performance at different levels of proteinuria. Measures of agreement were reanalyzed in relation to allograft histology in 76 patients with kidney biopsies performed for cause before enrolment in the study.

RESULTS

For ePER in the first morning urine, percent bias ranged from 1 to 28% and accuracy (within 30% of 24-h collection) ranged from 56 to 73%. For the second morning urine, percent bias ranged from 2 to 11%, and accuracy ranged from 71 to 78%. The accuracy of ePER (within 30%) in first and second morning urine progressively increased from 56 and 71% for low-grade proteinuria (150-299 mg/day) to 60 and 74% for moderate proteinuria (300-999 mg/day), and to 73 and 78% for high-grade proteinuria (≥1000 mg/day). Measures of agreement were similar across histologic phenotypes of allograft injury.

CONCLUSIONS

The ability of ePER to accurately predict 24-h proteinuria in kidney transplant recipients is modest. However, accuracy improves with an increase in proteinuria. Given the similar accuracy of ePER measurements in first and second morning urine, second morning urine can be used to monitor protein excretion.

Feasibility and impact of laparoscopic sleeve gastrectomy after renal transplantation on comorbidities, graft function and quality of life

Background

The aim of this study is to clarify the feasibility and effect of laparoscopic sleeve gastrectomy (LSG) on comorbidities, graft function and quality of life in patients who underwent renal transplantation (RT).

Methods

This is a retrospective review of five patients who underwent LSG after RT. Demographic data, anthropometric parameters, the effect on comorbidities, postoperative course, immunosuppressive medications, causes of RT, renal function, the survival of graft, and quality of life after SG in obese patients with a history of RT were assessed using BAROS–Moorhead–Ardelt survey

Results

From September 2015 to September 2019, 5 renal transplant patients underwent LSG; three female, and two male. Median body mass index (BMI) decreased from 42.17 kg/m² (range 36–55) before surgery to 28.16 kg/m² (range 25–42) after surgery. Improvement in blood pressure, triglyceride, and cholesterol levels was observed, and all cases were able to decrease their medications. Insulin was stopped and replaced with linagliptin in all diabetic patients. Graft function improved, and proteinuria level decreased in all cases. All patients reported to have an excellent quality of life.

Conclusion

LSG showed excellent outcomes in this high-risk group of patients regarding comorbidities, graft function and quality of life

Novel options for failing allograft in kidney transplanted patients to avoid or defer dialysis therapy

PURPOSE OF REVIEW

Despite improvement in short-term renal allograft survival in recent years, renal transplant recipients (RTR) have poorer long-term allograft outcomes. Allograft function slowly declines with periods of stable function similar to natural progression of chronic kidney disease in nontransplant population. Nearly all RTR transitions to failing renal allograft (FRG) period and require transition to dialysis. Conservative chronic kidney disease management before transition to end-stage renal disease is an increasingly important topic; however, there is limited data in RTR regarding how to delay dialysis initiation with conservative management.

RECENT FINDINGS

Since immunological and nonimmunological factors unique to RTR contribute to decline in allograft function, therapies to slow progression of FRG should take both sets of factors into account. Renal replacement therapy either incremental dialysis or rekidney transplantation should be explored. This required taking benefits and risks of continuing immunosuppressive medications into account when allograft nephrectomy may be necessary.

SUMMARY

FRG may benefit from various interventions to slow progression of worsening allograft function. Until there are stronger evidence to guide interventions to preserve renal function, extrapolating evidence from nontransplant patients and clinical judgment are necessary. The goal is to provide individualized care for conservative management of RTR with FRG.

Albuminuria and Allograft Failure, Cardiovascular Disease Events, and All-Cause Death in Stable Kidney Transplant Recipients: A Cohort Analysis of the FAVORIT Trial

RATIONALE & OBJECTIVE

Cardiovascular disease (CVD) is common and overall graft survival is suboptimal among kidney transplant recipients. Although albuminuria is a known risk factor for adverse outcomes among persons with native chronic kidney disease, the relationship of albuminuria with cardiovascular and kidney outcomes in transplant recipients is uncertain.

STUDY DESIGN

Post hoc longitudinal cohort analysis of the Folic Acid for Vascular Outcomes Reduction in Transplantation (FAVORIT) Trial.

SETTING & PARTICIPANTS

Stable kidney transplant recipients with elevated homocysteine levels from 30 sites in the United States, Canada, and Brazil.

PREDICTOR

Urine albumin-creatinine ratio (ACR) at randomization.

OUTCOMES

Allograft failure, CVD, and all-cause death.

ANALYTICAL APPROACH

Multivariable Cox models adjusted for age; sex; race; randomized treatment allocation; country; systolic and diastolic blood pressure; history of CVD, diabetes, and hypertension; smoking; cholesterol; body mass index; estimated glomerular filtration rate (eGFR); donor type; transplant vintage; medications; and immunosuppression.

RESULTS

Among 3,511 participants with complete data, median ACR was 24 (Q1-Q3, 9-98) mg/g, mean eGFR was 49±18 (standard deviation) mL/min/1.73m², mean age was 52±9 years, and median graft vintage was 4.1 (Q1-Q3, 1.7-7.4) years. There were 1,017 (29%) with ACR < 10mg/g, 912 (26%) with ACR of 10 to 29mg/g, 1,134 (32%) with ACR of 30 to 299mg/g, and 448 (13%) with ACR ≥ 300mg/g. During approximately 4 years, 282 allograft failure events, 497 CVD events, and 407 deaths occurred. Event rates were higher at both lower eGFRs and higher ACR. ACR of 30 to 299 and ≥300mg/g relative to ACR < 10mg/g were independently associated with graft failure (HRs of 3.40 [95% CI, 2.19-5.30] and 9.96 [95% CI, 6.35-15.62], respectively), CVD events (HRs of 1.25 [95% CI, 0.96-1.61] and 1.55 [95% CI, 1.13-2.11], respectively), and all-cause death (HRs of 1.65 [95% CI, 1.23-2.21] and 2.07 [95% CI, 1.46-2.94], respectively).

LIMITATIONS

No data for rejection; single ACR assessment.

CONCLUSIONS

In a large population of stable kidney transplant recipients, elevated baseline ACR is independently associated with allograft failure, CVD, and death. Future studies are needed to evaluate whether reducing albuminuria improves these outcomes.

Renal Doppler Resistance Indices in Kidney Transplant Recipients With Proteinuria

BACKGROUND

The onset of proteinuria in renal transplant recipients may be associated with an increased risk of allograft failure. Little is known about the relationships between factors influencing proteinuria and the Doppler ultrasound (DU) intrarenal resistive index (RI) and pulsatility index (PI) among donor recipients with proteinuria <1000 mg/24 h.

METHODS

We assessed correlations between the DU RI and PI and protein content in 93 selected renal transplant recipients: 62 patients with proteinuria 100 to 299 mg/24 h, 16 patients with proteinuria 300 to 499 mg/24 h, and 15 patients with proteinuria 500 to 999 mg/24 h. All patients underwent transplantation in a single center and were monitored by DU for at least 28 months post-transplantation.

RESULTS

The DU RI values of the proteinuria 100 to 299 mg/24 h, 300 to 499 mg/24 h, and 500 to 999 mg/24 h groups were 0.67 ± 0.05; 0.65 ± 0.04, and 0.64 ± 0.07, respectively, and the PI values were 1.21 ± 0.20, 1.10 ± 0.14, and 1.15 ± 0.22, respectively. Multivariate logistic regression analysis revealed a correlation between group 100 to 299 mg/24 h and RI values, serum creatinine, living donor (R² = 19.6%, P = .05); group 300 to 499 mg/24 h and the RI, PI values, cadaver donor (R² = 17.5%, P = .001); and group 500 to 999 mg/24 h and the RI, PI values, serum creatinine, graft survival (R² = 15.4%, P = .005).

CONCLUSIONS

Among donor recipients with proteinuria <1000 mg/24 h, DU RI values were <0.72 and PI values were <1.41 and correlations were revealed between the incidence of proteinuria and factors such as the RI, PI, and serum creatinine level.

Campath, calcineurin inhibitor reduction, and chronic allograft nephropathy (the 3C Study) - results of a randomized controlled clinical trial

Calcineurin inhibitors (CNIs, eg, tacrolimus) reduce short-term kidney transplant failure, but chronic nephrotoxicity may contribute to late transplant loss. Elective conversion to inhibitors of the mammalian target of rapamycin (mTOR, eg, sirolimus) pathway might avoid long-term CNI renal damage and improve outcomes. The 3C Study was a pragmatic randomized controlled trial of sequential randomizations between alemtuzumab and basiliximab induction therapy (at the time of surgery) and between tacrolimus and sirolimus maintenance therapy at 6 months posttransplantation. The primary outcome of this analysis was estimated glomerular filtration rate (eGFR) at 18 months after maintenance therapy randomization; 197 patients were assigned sirolimus-based and 197 to tacrolimus-based therapy. Allocation to sirolimus had no significant effect on eGFR at 18 months: baseline-adjusted mean (SEM) eGFR was 53.7 (0.9) mL/min/1.73 m² in the sirolimus group versus 54.6 (0.9) mL/min/1.73 m² in the tacrolimus group (P = .50). Biopsy-proven acute rejection (29 [14.7%]) vs 6 [3.0%]; P < .001) and serious infections (defined as opportunistic infections or those requiring hospitalization; 95 [48.2%] vs 70 [35.5%]; P = .008) were more common among participants allocated sirolimus. Compared with tacrolimus-based therapy, sirolimus-based maintenance therapy did not improve transplant function at 18 months after conversion and was associated with significant hazards of rejection and infection. ClinicalTrials.gov identifier NCT01120028 and ISRCTN88894088.

Early Steroid Withdrawal Compared With Standard Immunosuppression in Kidney Transplantation - Interim Analysis of the Amsterdam-Leiden-Groningen Randomized Controlled Trial

BACKGROUND

The optimal immunosuppressive regimen in kidney transplant recipients, delivering maximum efficacy with minimal toxicity, is unknown.

METHODS

The Amsterdam, LEiden, GROningen trial is a randomized, multicenter, investigator-driven, noninferiority, open-label trial in 305 kidney transplant recipients, in which 2 immunosuppression minimization strategies—one consisting of early steroid withdrawal, the other of tacrolimus minimization 6 months after transplantation—were compared with standard immunosuppression with basiliximab, corticosteroids, tacrolimus, and mycophenolic acid. The primary endpoint was kidney function. Secondary endpoints included death, primary nonfunction, graft failure, rejection, discontinuation of study medication, and a combined endpoint of treatment failure. An interim analysis was scheduled at 6 months, that is, just before tacrolimus minimization.

RESULTS

This interim analysis revealed no significant differences in Modification of Diet in Renal Disease between the early steroid withdrawal group and the standard immunosuppression groups (43.2 mL/min per 1.73 m² vs 45.0 mL/min per 1.73 m², P = 0.408). There were also no significant differences in the secondary endpoints of death (1.0% vs 1.5%; P = 0.737), primary nonfunction (4.1% vs 1.5%, P = 0.159), graft failure (3.1% vs 1.5%, P = 0.370), rejection (18.6% vs 13.6%, P = 0.289), and discontinuation of study medication (19.6% vs 12.6%, P = 0.348). Treatment failure, defined as a composite endpoint of these individual secondary endpoints, was more common in the early steroid withdrawal group (P = 0.027), but this group had fewer serious adverse events and a more favorable cardiovascular risk profile.

CONCLUSIONS

Based on these interim results, early steroid withdrawal is a safe short-term immunosuppressive strategy. Long-term outcomes, including a comparison with tacrolimus minimization after 6 months, will be reported in the final 2-year analysis.

Albuminuria in kidney transplant recipients is associated with increased urinary serine proteases and activation of the epithelial sodium channel

Albuminuria predicts adverse renal outcome in kidney transplant recipients. The present study addressed the hypothesis that albuminuria is associated with increased urine serine proteases with the ability to activate the epithelial sodium channel (ENaC) and with greater extracellular volume and higher blood pressure. In a cross-sectional design, kidney transplant recipients with ( n = 18) and without ( n = 19) albuminuria were included for office blood pressure measurements, estimation of volume status by bioimpedance, and collection of spot urine and plasma samples. Urine was analyzed for serine proteases and for the ability to activate ENaC current in vitro. Urine exosome protein was immunoblotted for prostasin and γ-ENaC protein. In the present study, it was found that, compared with nonalbuminuria (8.8 mg/g creatinine), albuminuric (1,722 mg/g creatinine) kidney transplant recipients had a higher systolic and diastolic blood pressure, despite receiving significantly more antihypertensives, and a greater urinary total plasminogen, active plasmin, active urokinase-type plasminogen activator, and prostasin protein abundance, which correlated significantly with u-albumin. Fluid overload correlated with systolic blood pressure, urinary albumin/creatinine, and plasminogen/creatinine. Urine from albuminuric kidney transplant recipients evoked a greater amiloride- and aprotinin-sensitive inward current in single collecting duct cells (murine cell line M1). γENaC subunits at 50 and 75 kDa showed increased abundance in urine exosomes from albuminuric kidney transplant recipients when compared with controls. These findings show that albuminuria in kidney transplant recipients is associated with hypertension, ability of urine to proteolytically activate ENaC current, and increased abundance of γENaC. ENaC activity could contribute to hypertension and adverse outcome in posttransplant proteinuria.

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.

Anti-inflammatory profile of paricalcitol in kidney transplant recipients

BACKGROUND AND OBJECTIVES

Paricalcitol, a selective vitamin D receptor activator, is used to treat secondary hyperparathyroidism in kidney transplant patients. Experimental and clinical studies in non-transplant kidney disease patients have found this molecule to have anti-inflammatory properties. In this exploratory study, we evaluated the anti-inflammatory profile of paricalcitol in kidney-transplant recipients.

METHODS

Thirty one kidney transplant recipients with secondary hyperparathyroidism completed 3 months of treatment with oral paricalcitol (1μg/day). Serum concentrations and gene expression levels of inflammatory cytokines in peripheral blood mononuclear cells were analysed at the beginning and end of the study.

RESULTS

Paricalcitol significantly decreased parathyroid hormone levels with no changes in calcium and phosphorous. It also reduced serum concentrations of interleukin (IL)-6 and tumour necrosis factor-alpha (TNF-α) by 29% (P<0.05) and 9.5% (P<0.05) compared to baseline, respectively. Furthermore, gene expression levels of IL-6 and TNF-α in peripheral blood mononuclear cells decreased by 14.1% (P<0.001) and 34.1% (P<0.001), respectively. The ratios between pro-inflammatory cytokines (TNF-α and IL-6) and anti-inflammatory cytokines (IL-10), both regarding serum concentrations and gene expression, also experienced a significant reduction.

CONCLUSIONS

Paricalcitol administration to kidney transplant recipients has been found to have beneficial effects on inflammation, which may be associated with potential clinical benefits.

Practical Recommendations for Long-term Management of Modifiable Risks in Kidney and Liver Transplant Recipients: A Guidance Report and Clinical Checklist by the Consensus on Managing Modifiable Risk in Transplantation (COMMIT) Group

Short-term patient and graft outcomes continue to improve after kidney and liver transplantation, with 1-year survival rates over 80%; however, improving longer-term outcomes remains a challenge. Improving the function of grafts and health of recipients would not only enhance quality and length of life, but would also reduce the need for retransplantation, and thus increase the number of organs available for transplant. The clinical transplant community needs to identify and manage those patient modifiable factors, to decrease the risk of graft failure, and improve longer-term outcomes.COMMIT was formed in 2015 and is composed of 20 leading kidney and liver transplant specialists from 9 countries across Europe. The group's remit is to provide expert guidance for the long-term management of kidney and liver transplant patients, with the aim of improving outcomes by minimizing modifiable risks associated with poor graft and patient survival posttransplant.The objective of this supplement is to provide specific, practical recommendations, through the discussion of current evidence and best practice, for the management of modifiable risks in those kidney and liver transplant patients who have survived the first postoperative year. In addition, the provision of a checklist increases the clinical utility and accessibility of these recommendations, by offering a systematic and efficient way to implement screening and monitoring of modifiable risks in the clinical setting.

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.

Estimating glomerular filtration rate in kidney transplantation: Still searching for the best marker

Kidney transplantation is the treatment of choice for end-stage renal disease. The evaluation of graft function is mandatory in the management of renal transplant recipients. Glomerular filtration rate (GFR), is generally considered the best index of graft function and also a predictor of graft and patient survival. However GFR measurement using inulin clearance, the gold standard for its measurement and exogenous markers such as radiolabeled isotopes ((51)Cr EDTA, (99m)Tc DTPA or (125)I Iothalamate) and non-radioactive contrast agents (Iothalamate or Iohexol), is laborious as well as expensive, being rarely used in clinical practice. Therefore, endogenous markers, such as serum creatinine or cystatin C, are used to estimate kidney function, and equations using these markers adjusted to other variables, mainly demographic, are an attempt to improve accuracy in estimation of GFR (eGFR). Nevertheless, there is some concern about the inability of the available eGFR equations to accurately identify changes in GFR, in kidney transplant recipients. This article will review and discuss the performance and limitations of these endogenous markers and their equations as estimators of GFR in the kidney transplant recipients, and their ability in predicting significant clinical outcomes.

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.

Laparoscopic sleeve gastrectomy as a weight reduction strategy in obese patients after kidney transplantation

Morbid obesity is associated with increased graft loss and shortened graft survival in kidney transplant patients. Treating obesity in transplant patients may improve graft outcomes. Laparoscopic sleeve gastrectomy (LSG), an effective bariatric operation, is relatively unlikely to interfere with absorption of anti-rejection medications. Data on relevant renal function parameters were collected from all LSGs performed on renal transplant patients at our center (n = 10). The procedure was successful in eight patients, with no mortality, graft rejection or dysfunction. The median age and follow-up were 57 years and 14 months, respectively. Seven patients had over 1 year of follow-up. The median preoperative weight and BMI were 119 kg (96-152) and 42 kg/m(2) (37-49), respectively. The median hospital stay was 4 days. The median postoperative weight and BMI at 6 months and 1 year were 86 kg and 31 kg/m(2) and 83 kg and 29 kg/m(2) , respectively. Urinary protein excretion and serum creatinine decreased significantly in all patients (p < 0.05). One patient developed two complications, acute renal failure and sleeve stricture, both of which resolved with treatment. LSG provided effective weight loss in renal transplant patients without adverse effects on graft function and immunosuppression.

Significance of urinary proteome pattern in renal allograft recipients

Urinary proteomics is developing as a platform of urinary biomarkers of immense potential in recent years. The definition of urinary proteome in the context of renal allograft and characterization of different proteome patterns in various graft dysfunctions have led to the development of a distinct science of this noninvasive tool. Substantial numbers of studies have shown that different renal allograft disease states, both acute and chronic, could portray unique urinary proteome pattern enabling early diagnosis of graft dysfunction and proper manipulation of immunosuppressive strategy that could impact graft prognosis. The methodology of the urinary proteome is nonetheless not more complex than that of other sophisticated assays of conventional urinary protein analysis. Moreover, the need for a centralized database is also felt by the researchers as more and more studies have been presenting their results from different corners and as systems of organizing these newly emerging data being developed at international and national levels. In this context concept of urinary proteomics in renal allograft recipients would be of significant importance in clinical transplantation.

Neopterin is associated with cardiovascular events and all-cause mortality in renal transplant patients

BACKGROUND

Inflammatory markers show significant associations with cardiovascular events and all-cause mortality after kidney transplantation. Neopterin, reflecting interferon-γ-release, may better reflect the proinflammatory state of recipients than less specific markers.

METHODS

Kidney transplant recipients in the Assessment of LEscol in Renal Transplant (ALERT) trial were examined and investigated for an association between serum neopterin and subsequent clinical events: graft loss, major cardiovascular events (MACE) and all-cause mortality.

RESULTS

After adjustment for established and emerging risk factors neopterin expressed as neopterin-to-creatinine ratio was significantly associated with MACE (p = 0.009) and all-cause mortality (p = 0.002). Endpoints were more frequent with increasing quartiles of neopterin-to-creatinine ratio. The incidence rates of MACE and all-cause mortality were significantly increased in the upper quartiles compared with the first.

CONCLUSIONS

This long-term prospective analysis in stable kidney allograft recipients suggests that neopterin is associated with long-term risk of cardiovascular events and all-cause mortality, but not renal outcomes.

IVIg treatment reduces catalytic antibody titers of renal transplanted patients

Catalytic antibodies are immunoglobulins endowed with enzymatic activity. Catalytic IgG has been reported in several human autoimmune and inflammatory diseases. In particular, low levels of catalytic IgG have been proposed as a prognostic marker for chronic allograft rejection in patients undergoing kidney transplant. Kidney allograft is a treatment of choice for patients with end-stage renal failure. Intravenous immunoglobulins, a therapeutic pool of human IgG, is used in patients with donor-specific antibodies, alone or in conjunction with other immunosuppressive treatments, to desensitize the patients and prevent the development of acute graft rejection. Here, we followed for a period of 24 months the levels of catalytic IgG towards the synthetic peptide Pro-Phe-Arg-methylcoumarinimide in a large cohort of patients undergoing kidney transplantation. Twenty-four percent of the patients received IVIg at the time of transplantation. Our results demonstrate a marked reduction in levels of catalytic antibodies in all patients three months following kidney transplant. The decrease was significantly pronounced in patients receiving adjunct IVIg therapy. The results suggests that prevention of acute graft rejection using intravenous immunoglobulins induces a transient reduction in the levels of catalytic IgG, thus potentially jeopardizing the use of levels of catalytic antibodies as a prognosis marker for chronic allograft nephropathy.

Ambulatory blood pressure monitoring in pediatric renal transplantation

Hypertension is a common and serious complication after renal transplantation. It is an important risk factor for graft loss and adverse cardiovascular outcomes. Blood pressure (BP) in transplanted children should be measured not only by clinic BP (cBP) measurement, but also by ambulatory blood pressure monitoring (ABPM), because ABPM has distinct advantages over cBP, specifically the ability to reveal nocturnal, masked or white-coat hypertension. These types of hypertension are common in transplanted children (nocturnal hypertension 36-71 %, masked hypertension 24-45 %). It may also reveal uncontrolled hypertension in treated children, thereby improving control of hypertension. Regular use of ABPM and ABPM-guided therapy of hypertension may help to decrease cardiovascular and renal target organ damage in transplanted children. Therefore, ABPM should be routinely performed in all transplanted children at least once a year, regardless of the values of cBP.

Significance of urine diagnostic tests after renal transplantation

BACKGROUND

Validity, reliability and clinical value of classical urinary parameters for transplant monitoring are controversial. Urinary parameters were analyzed regarding cost-effectiveness, frequency of urinary tract infection and prediction of renal graft function and rejection.

METHODS

Urinary parameters of the first two postoperative weeks of 120 renal transplant patients were retrospectively correlated with the postoperative course.

RESULTS

Creatinine levels were significantly different on each postoperative day between the groups with and without rejection. Osmolaluria, diuresis and serum creatinine are equivalent in predicting graft rejection. Osmolaluria is not suitable as a distinguishing criterion between graft rejection and other complications. Measurement of glucosuria has no diagnostic value. Proteinuria has no prognostic relevance regarding rejection, although proteinuria >0.5g/l occurred more often in patients with rejection. Despite antibiotic prophylaxis with co-trimoxazole, 41 of 120 patients (34%) suffered from urinary tract infection (UTI; mostly E. coli) within the first 14 days after transplantation.

CONCLUSIONS

The measurement of some classical urinary parameters delivers no diagnostic gain. UTIs are frequent despite antibiotic prophylaxis, but the use of urine cultures makes sense only if a (cheaper) semiquantitative test is positive.

Cystatin C and albuminuria as predictors of long-term allograft outcomes in kidney transplant recipients

Although cystatin C (Cys) and albuminuria (Alb) are predictors of end-stage renal disease in the general population, there are limited data about the performance of these markers alone or combined with respect to the prediction of the kidney transplant outcome. We assessed the ability of one-yr creatinine (Cr), MDRD equation, Cys, Hoek equation, Alb, the logarithm of albuminuria (LogAlb), and two products of these variables for predicting death-censored graft loss (DCGL) in 127 kidney transplant recipients. Mean follow-up time was 5.6 ± 1.7 yr. During this time, 18 patients developed DCGL. The area under the receiver operating characteristic curve for DCGL ranged from 71.1% to 85.4%, with Cys*LogAlb being the best predictor. Cys-based variables and variables combining LogAlb and renal function estimates have better discrimination ability than Cr-based variables alone. After multivariate analysis, quartiles of all one-yr variables (except of Cr and MDRD) were independent predictors for DCGL. Predictors combining Alb and a Cr- or Cys-based estimate of renal function performed better than those markers alone to predict DCGL. Cys-based predictors performed better than Cr-based predictors. Using a double-marker in kidney transplantation, it is possible to identify the highest risk group in which to prioritize specialty care.

Risk factors for graft loss and mortality after renal transplantation according to recipient age: a prospective multicentre study

BACKGROUND

To describe the causes of graft loss, patient death and survival figures in kidney transplant patients in Spain based on the recipient's age.

METHODS

The results at 5 years of post-transplant cardiovascular disease (CVD) patients, taken from a database on CVD, were prospectively analysed, i.e. a total of 2600 transplanted patients during 2000-2002 in 14 Spanish renal transplant units, most of them receiving their organ from cadaver donors. Patients were grouped according to the recipient's age: Group A: <40 years, Group B: 40-60 years and Group C: >60 years. The most frequent immunosuppressive regimen included tacrolimus, mycophenolate mofetil and steroids.

RESULTS

Patients were distributed as follows: 25.85% in Group A (>40 years), 50.9% in Group B (40-60 years) and 23.19% in Group C (>60). The 5-year survival for the different age groups was 97.4, 90.8 and 77.7%, respectively. Death-censored graft survival was 88, 84.2 and 79.1%, respectively, and non death-censored graft survival was 82.1, 80.3 and 64.7%, respectively. Across all age groups, CVD and infections were the most frequent cause of death. The main causes of graft loss were chronic allograft dysfunction in patients <40 years old and death with functioning graft in the two remaining groups. In the multivariate analysis for graft survival, only elevated creatinine levels and proteinuria >1 g at 6 months post-transplantation were statistically significant in the three age groups. The patient survival multivariate analysis did not achieve a statistically significant common factor in the three age groups.

CONCLUSIONS

Five-year results show an excellent recipient survival and graft survival, especially in the youngest age group. Death with functioning graft is the leading cause of graft loss in patients >40 years. Early improvement of renal function and proteinuria together with strict control of cardiovascular risk factors are mandatory.

Clinical significance of proteinuria at posttransplant year 1 in kidney transplantation

PURPOSE

Proteinuria in the nontransplant population is a progressive renal disease. We analyzed the prevalence and clinical significance of proteinuria as well as factors related to its degree at posttransplant year 1 among kidney transplant recipients.

METHODS

We measured protein in a 24-hour urine among 644 recipients from January 1996 to December 2010.

RESULTS

Among 372 male and 272 female recipients, the mean amount of urinary protein was 424.4 ± 1010 mg/d (range, 13.88-8691) including 388 (60.2%) subjects with microproteinuria and the other 256 (39.8%) with overt proteinuria. Nephrotic range proteinuria was observed in 17 (2.6%) and nonnephritic range proteinuria, in 239 (37.1%) recipients. The latter cohort was categorized into low-grade proteinuria (n = 224; 34.8%) and high-grade proteinuria (n = 15; 2.3%). Proteinuria at posttransplant 1 year highly correlated with serum creatinine values at posttransplant years 1 and 2 as well as estimated glomerular filtration rate but not creatinine clearance at postoperative year 2. A greater incidence of graft loss was observed among recipients with more severe proteinuria. Males, recipients with anti-hepatitis C virus antibody, unrelated donors, anti-thymocyte immunoglobulin at the time of reperfusion, maintenance immunosuppression with cyclosporine or without mycophenolate mofetil were strongly associated with the amount of proteinuria.

CONCLUSION

This study demonstrated the prevalence of proteinuria in kidney transplant recipient to be high. The presence as well as level of proteinuria were predictive markers for inferior allograft function.

The prevalence of immunologic injury in renal allograft recipients with de novo proteinuria

Post-transplant proteinuria is a common complication after renal transplantation; it is associated with reduced graft and recipient survival. However, the prevalence of histological causes has been reported with considerable variation. A clinico-pathological re-evaluation of post-transplant proteinuria is necessary, especially after dismissal of the term “chronic allograft nephropathy,” which had been considered to be an important cause of proteinuria. Moreover, urinary protein can promote interstitial inflammation in native kidney, whether this occurs in renal allograft remains unknown. Factors that affect the graft outcome in patients with proteinuria also remain unclear. Here we collected 98 cases of renal allograft recipients who developed proteinuria after transplant, histological features were characterized using Banff scoring system. Cox proportional hazard regression models were used for graft survival predictors. We found that transplant glomerulopathy was the leading (40.8%) cause of post-transplant proteinuria. Immunological causes, including transplant glomerulopathy, acute rejection, and chronic rejection accounted for the majority of all pathological causes of proteinuria. Nevertheless, almost all patients that developed proteinuria had immunological lesions in the graft, especially for interstitial inflammation. Intraglomerular C3 deposition was unexpectedly correlated with the severity of proteinuria. Moreover, the severity of interstitial inflammation was an independent risk factor for graft loss, while high level of hemoglobin was a protective factor for graft survival. This study revealed a predominance of immunological parameters in renal allografts with post-transplant proteinuria. These parameters not only correlate with the severity of proteinuria, but also with the outcome of the graft.

Incidence of cardiovascular events after kidney transplantation and cardiovascular risk scores: study protocol

Background

Cardiovascular disease (CVD) is the major cause of death after renal transplantation. Not only conventional CVD risk factors, but also transplant-specific risk factors can influence the development of CVD in kidney transplant recipients.

The main objective of this study will be to determine the incidence of post-transplant CVD after renal transplantation and related factors. A secondary objective will be to examine the ability of standard cardiovascular risk scores (Framingham, Regicor, SCORE, and DORICA) to predict post-transplantation cardiovascular events in renal transplant recipients, and to develop a new score for predicting the risk of CVD after kidney transplantation.

Methods/Design

Observational prospective cohort study of all kidney transplant recipients in the A Coruña Hospital (Spain) in the period 1981-2008 (2059 transplants corresponding to 1794 patients).

The variables included will be: donor and recipient characteristics, chronic kidney disease-related risk factors, pre-transplant and post-transplant cardiovascular risk factors, routine biochemistry, and immunosuppressive, antihypertensive and lipid-lowering treatment. The events studied in the follow-up will be: patient and graft survival, acute rejection episodes and cardiovascular events (myocardial infarction, invasive coronary artery therapy, cerebral vascular events, new-onset angina, congestive heart failure, rhythm disturbances and peripheral vascular disease).

Four cardiovascular risk scores were calculated at the time of transplantation: the Framingham score, the European Systematic Coronary Risk Evaluation (SCORE) equation, and the REGICOR (Registre Gironí del COR (Gerona Heart Registry)), and DORICA (Dyslipidemia, Obesity, and Cardiovascular Risk) functions.

The cumulative incidence of cardiovascular events will be analyzed by competing risk survival methods. The clinical relevance of different variables will be calculated using the ARR (Absolute Risk Reduction), RRR (Relative Risk Reduction) and NNT (Number Needed to Treat).

The ability of different cardiovascular risk scores to predict cardiovascular events will be analyzed by using the c index and the area under ROC curves. Based on the competing risks analysis, a nomogram to predict the probability of cardiovascular events after kidney transplantation will be developed.

Discussion

This study will make it possible to determine the post-transplant incidence of cardiovascular events in a large cohort of renal transplant recipients in Spain, to confirm the relationship between traditional and transplant-specific cardiovascular risk factors and CVD, and to develop a score to predict the risk of CVD in these patients.

Tolerability of everolimus-based immunosuppression in maintenance liver transplant recipients

BACKGROUND

The aim of this study was to evaluate the tolerability of the conversion from calcineurin inhibitor (CNI) to everolimus (ERL) in maintenance liver transplant (LT) recipients.

METHODS

From January 2005 to March 2008, ERL was introduced after LT as maintenance immunosuppressive therapy because of (i) de novo or recurrent cancer after LT, (ii) pre-existing liver carcinoma on the liver explant or (iii) CNI toxicity. CNI dosage was progressively reduced until discontinuation.

RESULTS

The study population included 94 patients, of mean age 57 ± 10. The mean delay between LT and ERL introduction was 5 ± 5 yr. After a mean follow-up of 12 ± 7 months, 70% of the patients did present at least one side effect. The mean trough level of ERL was 6 μg/L at the end of follow-up. Main side effects included hyperlipidemia (37%), dermatitis (19%), mucositis (15%), and proteinuria (18%). Biopsy-proven acute rejection occurred in 9% of patients. Global ERL discontinuation rate was 21% (16% because of side effects).

CONCLUSIONS

The results of our experience indicate that conversion to ERL is associated with adverse effects in 70% of patients leading to drug discontinuation in 16% (and amenable to dose reduction in the remainders). Longer follow-up periods are necessary to capture the impact of ERL fully on renal function and survival in cancer patients.

Kidney and recipient weight incompatibility reduces long-term graft survival

Long-term function of kidney allografts depends on multiple variables, one of which may be the compatibility in size between the graft and the recipient. Here, we assessed the long-term consequences of the ratio of the weight of the kidney to the weight of the recipient (KwRw ratio) in a multicenter cohort of 1189 patients who received a transplant between 1995 and 2006. The graft filtration rate increased by a mean of 5.74 ml/min between the third and sixth posttransplantation months among patients with a low KwRw ratio (<2.3 g/kg; P<0.0001). In this low KwRw ratio group, the graft filtration rate remained stable between 6 months and 7 years but then decreased at a mean rate of 3.17 ml/min per yr (P<0.0001). In addition, low KwRw ratios conferred greater risk for proteinuria, more antihypertensive drugs, and segmental or global glomerulosclerosis. Moreover, a KwRw ratio<2.3 g/kg associated with a 55% increased risk for transplant failure by 2 years of follow-up. In conclusion, incompatibility between graft and recipient weight is an independent predictor of long-term graft survival, suggesting that avoiding kidney and recipient weight incompatibility may improve late clinical outcome after kidney transplantation.

Ramipril in the treatment of proteinuria in children after renal transplantation

The efficacy and safety of ACEI in adult patients with hypertension and proteinuria after renal transplantation is proven however data on the effectiveness of ACEI in transplanted children are rare. The aim of the present study was to investigate the effect of ramipril on proteinuria and BP in children after R-Tx. Twelve transplanted children (median age 15.3 yr, median time after R-Tx 4.5 yr) with proteinuria with or without hypertension were prospectively treated with ramipril for six months. Proteinuria was assessed as protein/creatinine ratio. Office BP was evaluated and hypertension defined as BP > or =95th centile. Graft function was assessed (Schwartz formula). The starting dose of ramipril was 1.5 mg/m(2)/24-h. Proteinuria declined in 92% of children from a median 39 to 22 mg/mmol creatinine (p < 0.01). The median decline of proteinuria was 9 mg/mmol creatinine, it reached 23% of the initial values. The prevalence of hypertension did not change significantly (50% initially vs. 33% after six months). Graft function and serum potassium level did not change significantly, two children developed mild hyperkalemia. Ramipril can reduce proteinuria in most transplanted children; its antiproteinuric effect is exhibited even without BP lowering effect.

Increase in proteinuria >200 mg/g after late rejection is associated with poor graft survival

BACKGROUND

There is no information on the effects of proteinuria on outcomes following rejection.

METHODS

We addressed this question in a retrospective study of 925 kidney transplant recipients between January 2003 and December 2007. Selection criteria were based on (i) biopsy proven diagnosis of a first episode of acute rejection, and (ii) available data on urine protein to creatinine (UPC) ratios at baseline (lowest serum creatinine before biopsy), time of biopsy and 1 month after biopsy. We examined the effects of a change in UPC (DeltaUPC = UPC 1 month after biopsy-baseline UPC) on outcomes.

RESULTS

We identified 82 patients with both acute rejection and available data on proteinuria. Mean time (+/-SE) to acute rejection was 19 +/- 2.3 months, and patients were followed up for 38.7 +/- 2.6 months after transplant. Median DeltaUPC was 200 mg/g (95% confidence interval 0.00 to 0.300). Forty-two patients had a DeltaUPC > or =200 (high proteinuria group). Baseline characteristics were similar between high and low proteinuria groups except for more induction therapy with interleukin-2 receptor blockade in the former (71 vs. 47%, P = 0.04). Patient with DeltaUPC > or =200 had higher rates of graft loss (26 vs. 15%, P = 0.01) or combined graft loss or death (38 vs. 20%, P = 0.002 by log-rank). In univariate and multivariate Cox regression analyses, DeltaUPC > or =200 mg/g, sirolimus therapy 1 month after rejection and re-transplant status were significant factors associated with death-censored graft loss (hazard ratio (HR) 4.4, 14.9 and 6.2, P < or = 0.008) or combined graft loss or patient death (HR 3.8, 6.5 and 3.9, P < or = 0.03). Conclusions. An increase in proteinuria > or =200 mg/g after late acute rejection is associated with poor graft and patient outcomes. Clinical trials are needed to determine whether post-rejection anti-proteinuric strategies improve outcomes.

Proteinuria >0.5 g/d, a prevalent prognostic factor for patient and graft survival in kidney transplantation

Proteinuria >0.5 g/d (HP) and serum creatinine (Scr) >120 micromol/L (HSC) at three months, two and five yr were compared as prognostic factors in kidney transplantation. We retrospectively analyzed 454 first transplants (follow-up: 100 +/- 3.2 months). Donor/recipient age, sex, panel reactive antibody (PRA), HLA mismatches, cold ischemia time, delayed graft function, acute rejection, blood pressure and its treatment, diabetes and anti-calcineurin use were also evaluated. Cox proportional hazard regression with time-dependent covariates to control for potentially confounding factors was used to analyze survival. The Kaplan-Meier product-limit estimate for survival according to urine protein excretion (< or = or >0.5 g/d) or Scr (< or = or >120 micromol/L) along with the log-rank test for all comparisons were computed. Statistical significance was set with p-value < 0.05.

RESULTS

HSC is a prognostic factor of graft survival (HR: 2.54; 95% CI: 1.98-3.10; p < 0.01) only at five yr, but it does not predict mortality at any period. HP at three months (HR: 2.07; 95% CI: 1.70-2.43; p < 0.001) and at two yr 3.03 (2.54-3.51; p < 0.001) significantly predicts graft failure. HP at two yr is the prevailingly prognostic factor of patient survival in kidney transplantation (HR: 3.30; 95% CI: 1.94-5.62; p < 0.0001).

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

It is generally accepted that one-year post-transplant proteinuria over 0.5 gm per day has a negative impact on renal graft survival. In this study, the effects of minimal proteinuria less than 0.5 g/day were analyzed in 272 renal recipients who had survived for one year with a functioning graft. Recipients were classified by one-year post-transplant proteinuria: no proteinuria group (<0.2 g/day), minimal proteinuria group (0.2-0.5 g/day), and overt proteinuria group (>or=0.5 g/day). Recipients were followed up for 87.1+/-21 months after transplantation and 38 (13.9%) lost their graft during follow-up. Fifteen percent of patients had minimal proteinuria and 7.8% had overt proteinuria. Five-year graft survival in the minimal proteinuria group was 83.0%, and that in the overt proteinuria group was 70%, in contrast to 97.1% in the no proteinuria group (p=0.01 for trend). In a multivariate analysis, the minimal proteinuria group (relative risk [RR], 4.90; 95% confidence interval [CI], 2.09-11.46) and the overt proteinuria group (RR, 8.75; 95% CI, 3.29-23.29) had higher risks of graft failure than the no proteinuria group. Even minimal proteinuria at one year after transplantation was strongly associated with poor graft outcome. Therefore, it appears logical to consider a low level of proteinuria as a risk factor for graft survival in renal recipients.

[Proteinuria and renal transplantation]

The occurrence of proteinuria in transplant patients is a marker of poor prognosis. The augmentation of proteinuria is associated with an increased risk of patient death and graft loss. Even a low-level urinary protein excretion (0.5 g/d) has a highly significant negative impact on graft survival whether it is observed 1 or 3 months after transplantation. Urinary albumin excretion rate has also a major effect on risks of graft loss and death with functional kidney, macro-albuminuria increasing the risks of respectively 16.4 and 4.12 times comparatively to micro-albuminuria, which itself multiplies the risks by 14.2 and 5.5 respectively, compared to normo-albuminuria. In terms of factors causing proteinuria apparition, the role of proliferation signal inhibitors has been recently observed. Sirolimus, especially at high dose, in particular can induce the occurrence of proteinuria, which is reversible with treatment discontinuation, but only with a partial recovery of the renal function. Proteinuria may be explained by a direct glomerular impact of sirolimus on several podocyte markers.

Hydrolysis of coagulation factors by circulating IgG is associated with a reduced risk for chronic allograft nephropathy in renal transplanted patients

Chronic allograft nephropathy (CAN), a major cause of late allograft failure, is characterized by a progressive decline in graft function correlated with tissue destruction. Uncontrolled activation of the coagulation cascade by the stressed endothelium of the graft is thought to play an important role in the pathophysiology of CAN. In this study, we demonstrate that circulating IgG from renal-transplanted patients are endowed with hydrolytic properties toward coagulation factors VIII and IX, but fail to hydrolyze factor VII and prothrombin. The hydrolytic activity of IgG was reliably quantified by the measure of the hydrolysis of a fluorescent synthetic substrate for serine proteases: proline-phenylalanine-arginine-methylcoumarinamide (PFR-MCA). A retrospective case-control study indicated that an elevated hydrolysis rate of PFR-MCA by circulating IgG correlated with the absence of CAN lesions on protocol graft biopsy performed 2 years posttransplantation. We propose that circulating hydrolytic IgG may counterbalance the procoagulation state conferred by the activated endothelium by disrupting the amplification loop of thrombin generation which is dependent on factors VIII and IX. Interestingly, low rates of PFR-MCA hydrolysis, measured 3 mo posttransplantation, were predictive of CAN at 2 years down the lane. These data suggest that PFR-MCA hydrolysis may be used as a prognosis marker for CAN in renal-transplanted patients.

Early pulse pressure and low-grade proteinuria as independent long-term risk factors for new-onset diabetes mellitus after kidney transplantation

Risk factors for new-onset diabetes after transplantation (NODAT) need to be assessed in large cohorts. We retrospectively evaluated the impact of early (3 and 6 months after transplantation) proteinuria, urinary albumin excretion (UAE) and arterial pressure on NODAT in 828 Caucasian renal transplant recipients (median follow-up: 5.3 years; 5832 patient-years). The 10- and 20-year incidence of NODAT was 15.0% and 22.0%, respectively. Low-grade (<1 g/day) (HR: 2.04 [1.25-3.33], p = 0.0042) and very low-grade (<0.3 g/day) (HR: 2.21 [1.32-3.70], p = 0.0025) proteinuria were independent risk factors for NODAT. There was a dose-dependent relationship across UAE categories (increasing risk from normoalbuminuria to macroalbuminuria) with NODAT. Tacrolimus, sirolimus and beta-blockers (HR: 1.86 [1.07-3.22], p = 0.0277) were significantly associated with NODAT even after multiple adjustments, but not diuretics, angiotensin-converting enzyme inhibitors or angiotensin-receptor blockers. Systolic arterial pressure (HR per 10 mmHg: 1.16 [1.03-1.29], p = 0.0126) and pulse pressure (HR: 1.26 [1.12-1.43], p = 0.0002) were associated with NODAT. Only pulse pressure remained significant after adjustments. Patients at highest risks had early proteinuria and pulse pressure >60 mmHg. Early low-grade proteinuria and pulse pressure (in addition to beta-blockers) constitute independent risk factors for NODAT; they may be markers of the metabolic syndrome and/or vascular damage in renal transplant recipients.

Cardiovascular disease in transplant recipients: current and future treatment strategies

A cardiovascular disease event in a transplant recipient may be the result of a pretransplantation disease process, a direct effect of immunosuppressant medications, or the result of exposure to a variety of traditional and nontraditional risk factors after transplantation. Although the understanding of posttransplantation cardiovascular disease remains incomplete, there is evidence that the impact of posttransplantation cardiovascular disease has been decreased, through increased attention to this problem. In the absence of controlled studies to guide therapy, this review summarizes treatment of cardiovascular disease risk factors for which there is strong evidence of benefit in the nontransplantation setting, observational evidence of a similar risk in transplant recipients, and evidence that treatment can be safely administered to transplant recipients. Putative risk factors for posttransplantation cardiovascular disease for which the current level of evidence is insufficient to support specific treatment recommendations are also discussed. Potential new strategies to decrease the risk for cardiovascular disease events after transplantation in the future, including aggressive pretransplantation risk reduction, individualized treatments to prevent different types of cardiovascular disease, dedicated efforts to reduce cardiovascular disease events during transitions between dialysis and transplantation, and manipulation of immunosuppressant protocols, are also introduced.