International comparison and time trends of first kidney transplant recipient characteristics across Europe: an ERA Registry study

BACKGROUND

The aim of this study was to provide an overview of age, sex and primary renal disease (PRD) distribution among first kidney transplant recipients across Europe.

METHOD

The European Renal Association (ERA) Registry database was used to obtain data on patients aged 20 years or older receiving their first kidney transplant between 2010 and 2019 from 12 European countries. The numbers and percentages of recipients in each age, sex and PRD group were calculated by country, donor type and year.

RESULTS

In total, 99 543 adults received a first kidney transplant. Overall, 23% of the recipients were 65 years or older, 36% were female, and 21% had glomerulonephritis and 15% diabetes mellitus as PRD. Compared with deceased donor kidney transplant recipients, living donor kidney transplant recipients were less often 65 years or older (13% versus 26%), more often had glomerulonephritis (25% versus 20%) and less often diabetes mellitus (8% versus 17%) as PRD. We found large international differences, which were most prominent for age and PRD and less prominent for sex. Over time, the largest change in recipient characteristics was observed for the percentage of recipients aged 65 years or older, increasing from 18% in 2010 to 28% in 2019 for all countries combined with a similar trend in most countries.

CONCLUSION

We observed large differences for age and PRD distribution between recipients of living and deceased donor kidneys and between European countries. Over time, the percentage of older first kidney transplant recipients increased.

Novel transcriptomic signatures associated with premature kidney allograft failure

BACKGROUND

The power to predict kidney allograft outcomes based on non-invasive assays is limited. Assessment of operational tolerance (OT) patients allows us to identify transcriptomic signatures of true non-responders for construction of predictive models.

METHODS

In this observational retrospective study, RNA sequencing of peripheral blood was used in a derivation cohort to identify a protective set of transcripts by comparing 15 OT patients (40% females), from the TOMOGRAM Study (NCT05124444), 14 chronic active antibody-mediated rejection (CABMR) and 23 stable graft function patients ≥15 years (STA). The selected differentially expressed transcripts between OT and CABMR were used in a validation cohort (n = 396) to predict 3-year kidney allograft loss at 3 time-points using RT-qPCR.

FINDINGS

Archetypal analysis and classifier performance of RNA sequencing data showed that OT is clearly distinguishable from CABMR, but similar to STA. Based on significant transcripts from the validation cohort in univariable analysis, 2 multivariable Cox models were created. A 3-transcript (ADGRG3, ATG2A, and GNLY) model from POD 7 predicted graft loss with C-statistics (C) 0.727 (95% CI, 0.638-0.820). Another 3-transcript (IGHM, CD5, GNLY) model from M3 predicted graft loss with C 0.786 (95% CI, 0.785-0.865). Combining 3-transcripts models with eGFR at POD 7 and M3 improved C-statistics to 0.860 (95% CI, 0.778-0.944) and 0.868 (95% CI, 0.790-0.944), respectively.

INTERPRETATION

Identification of transcripts distinguishing OT from CABMR allowed us to construct models predicting premature graft loss. Identified transcripts reflect mechanisms of injury/repair and alloimmune response when assessed at day 7 or with a loss of protective phenotype when assessed at month 3.

FUNDING

Supported by the Ministry of Health of the Czech Republic under grant NV19-06-00031.

The Effect of Elective Ligation of the Arteriovenous Fistula on Cardiac and Renal Functions in Kidney Transplant Recipients

Key Points

Surgical AVF ligation in KTRs is associated with a significant increase in diastolic BP while systolic BP remains stable. AVF closure in KTRs leads to an improvement of LV and LA morphology and a decrease in serum NT-proBNP levels. There is no significant effect of AVF ligation on kidney allograft function: The eGFR remains stable over time.

Background

Kidney transplantation is considered as the best kidney replacement therapy, and arteriovenous fistula (AVF) is the preferred vascular access for hemodialysis. The systematic ligation of a functioning AVF in stable kidney transplant recipients (KTRs) remains debatable.

Methods

In this prospective study, we investigated the hemodynamic effect of the surgical closure of AVF in KTRs. Forty-three KTRs underwent an ambulatory BP monitoring before surgical closure of AVF (T0) and 12 months later (M12), as well as measurement of serum cardiac biomarkers (i.e. , soluble suppression of tumorigenicity 2, N-terminal pro b-type natriuretic peptide [NT-proBNP], and galectin-3). Serum tests were also performed 6 months after AVF closure (M6). An echocardiographic examination was performed at each time point. All serum creatinine values were collected to compare the individual eGFR slopes before versus after AVF closure. The latest measure of the AVF flow before kidney transplantation was recorded.

Results

Diastolic BP significantly rose from T0 to M12: +4.4±7.3 mm Hg (P = 0.0003) for 24h, +3.8±7.4 mm Hg (P = 0.0018) during the day, and +6.3±9.9 mm Hg (P = 0.0002) during the night, leading to an increased proportion of KTRs with European Society of Hypertension (ESH)-defined arterial hypertension after AVF ligation. No change was observed for systolic BP. NT-proBNP significantly dropped between T0 and M6 (345 [190; 553] to 230 [118; 458] pg/ml, P = 0.0001) and then remained stable from M6 to M12 while suppression of tumorigenicity 2 and galectin-3 levels did not change from T0 to M12. We observed a significant decrease in left ventricular (LV) end-diastolic volume, LV end-systolic volume, LV mass, interventricular septum diameter, left atrial volume, and tricuspid annular plane systolic excursion from T0 to M6 and then a stability from M6 to M12. LV ejection fraction and eGFR slope remained stable during the whole study. These observations remained unchanged after adjustment for AVF flow.

Conclusion

The closure of a patent AVF in KTRs is associated with elevation of diastolic BP, drop in serum NT-proBNP levels, reduction of left ventricular and atrial dimensions, and stability of eGFR slope.

Efficacy of Prolonged-release Tacrolimus After Conversion From Immediate-release Tacrolimus in Kidney Transplantation: A Retrospective Analysis of Long-term Outcomes From the ADMIRAD Study

Prolonged-release tacrolimus (PRT) may offer improved outcomes after kidney transplantation compared with immediate-release tacrolimus (IRT). However, data on outcomes beyond 5-y posttransplantation are lacking.

Methods

A retrospective, noninterventional chart review study examined long-term graft survival in adult kidney transplant participants in the Adherence Measurement in Stable Renal Transplant Patients Following Conversion From Prograf to Advagraf (ADMIRAD) clinical trial at 4 Belgian sites. Patients were randomized to receive once-daily PRT or twice-daily IRT for 6 mo, followed by treatment as per real-world clinical practice. Data were collected retrospectively from randomization day until December 31, 2018. Primary endpoints included efficacy failure, defined as a composite endpoint of graft loss, biopsy-confirmed acute rejection, and graft dysfunction. Secondary endpoints included overall patient survival and course of kidney function.

Results

This analysis included 78.5% of patients from ADMIRAD (n = 108 PRT; n = 64 IRT). The Kaplan-Meier survival rate without efficacy failure from randomization to year 5 was 0.741 (95% confidence interval [CI]: 0.647, 0.813) for the PRT group (n = 80), and 0.667 (95% CI: 0.536, 0.768) for the IRT group (n = 42) and remained higher for PRT throughout 10 y follow-up (P = 0.041). The Kaplan-Meier estimate of overall survival from the time of last transplant was 0.981 (95% CI: 0.928, 0.995) and 0.880 (95% CI: 0.802, 0.928) at 5 and 10 y in the PRT group. Kidney function parameters and tacrolimus trough levels remained stable over the follow-up period.

Conclusions

Patients in the ADMIRAD study who received PRT for up to 10 y had improved long-term outcomes compared with patients receiving IRT, with a consistent effect on both graft and patient survival.

[Delayed graft function : an ongoing clinical challenge]

Delayed Graft Function (DGF) is defined as the need for dialysis during the first week after transplantation. DGF is frequent and mostly derived from the ischemia/reperfusion cascade to which the graft is subjected throughout the transplantation process. A graft biopsy is recommended after 7 days of DGF to exclude an episode of acute rejection. Note that DGF per se is associated with an increased risk of acute graft rejection, as well as with a shorter long-term graft survival. Several strategies are being studied to mitigate the ischaemic damage, thereby improving graft quality. Among these, cellular therapy using mesenchymal stromal cells (MSC) is promising, in particular via the administration of MSC in the machine perfusion during the preservation of the graft. We will discuss here the different definitions of DGF and the main predictive factors of DGF, as well as the impact on the graft outcomes. The current strategies to prevent DGF will be briefly reviewed.

[Rare complication of a dog bite: Capnocytophaga species bacteremia followed by an hemolytic uremic syndrome]

Dog bites are a frequent reason for medical consultation. These can be responsible for severe infectious complications. Bacteria of the genus Capnocytophaga species are Gram-negative bacilli commonly found in the oral cavity of certain animals such as dogs and cats. Following a dog bite or wound contamination with animal spit, these bacteria can cause local (cellulitis), systemic and invasive manifestations (bacteremia, endocarditis, meningitis) or lead to rare and dreadful complications such as thrombotic microangiopathies. The identification of Capnocytophaga is slow due to their specific characteristics and their culture conditions. The treatment of Capnocytophaga species infections is based on antibiotic therapy with amoxicillin - clavulanic acid as the first choice. Although different types of Capnocytophaga have been described, C. Canimorsus appears to be associated with a higher rate of atypical complications. Here is the description of an immunocompetent patient who presented with C. Canimorsus bacteremia complicated by hemolytic uremic syndrome following a dog bite.

The prospective screening for SARS-CoV-2 S1/S2 antibodies delineates the factual incidence of COVID-19 and shows a sustained serological response post COVID-19 in kidney transplant recipients

BACKGROUND

The impact of immunosuppression on the occurrence of Coronavirus Disease 2019 (COVID-19) remains unclear.

METHODS

We conducted a prospective screening of anti-S1/S2 IgGs against SARS-CoV-2 Spike protein from March, 1 2020 to May, 15 2021 (prior to the vaccination campaign) in a cohort of 713 kidney transplant recipients (KTRs). In a first phase, the factual incidence and seroprevalence of COVID-19 was established in this cohort: cases diagnosed by serology were added to RT-PCR-based diagnoses to obtain the overall incidence of COVID-19 in both symptomatic and asymptomatic KTRs. In the second phase, the kinetics of the post-COVID-19 humoral response were studied, taking into account the severity of the disease defined by the need for oxygen therapy (group S, "severe") or not (group nS, "not severe").

RESULTS

The combined diagnostic approaches identified 138 COVID-19 cases (19.2%), with 37 diagnoses by serology (26.8%). The rate of asymptomatic KTRs reached 20.3% (28/138). Thirteen patients (9.4%) died from COVID-19. The seroconversion rate was 91.7% (99/108). The peak anti-S1/S2 IgG level was 85 [30-150] AU/ml and was similar between the S and nS groups (117 [38; 186] AU/ml versus 73 [23; 140] AU/ml). A high probability of persistence of anti-S1/S2 IgG post-COVID-19 was observed, with only 10.1% (7/69) of the patients having negated their serology during the 9-month follow-up.

CONCLUSION

Our pragmatic serological screening combined with RT-PCR tests provides a better estimation of the real incidence of COVID-19 in KTRs. A significant proportion of KTRs develop humoral immunity post COVID-19, which most often persists beyond 9 months.

MO542: Bone Mineral Density, Bone Micro-Architecture Evolution After Kidney Transplantation: A Prospective Cohort Study

BACKGROUND AND AIMS

Bone loss and mineral abnormalities are frequent in kidney transplant recipients (KTRs) and associated with a high risk of fracture, cardiovascular mortality and an increase in health care costs. In daily clinics, the detection of bone abnormalities after transplantation includes bone biomarkers and imaging technique [Dual Energy X-ray (DEXA)] to assess respectively the bone turnover and the bone mineral density (BMD), but with limitations. The high-resolution peripheral quantitative computed tomography (HR-pQCT) provides additional noninvasive information on bone microarchitecture and BMD with a better distinction between cortical and trabecular areas. The goal of our study is to evaluate the evolution of bone structure using HR-pQCT compared to standard technique (DXA) in a prospective cohort of KTRs.

METHOD

All patients referred for a single kidney transplant at the university hospital of Liège with no history of exposure to antiresorptive agents were eligible for inclusion (NCT04713774). Participants underwent baseline and 3-month biomarkers analysis, BMD measurements by DEXA. HR-pQCT images were obtained of the distal radius and distal tibia (non-dominant, non-fractured limb) using the XtremeCT device with standard protocols. HR-pQCT assessed quantitative measurement of the volumetric density of trabecular and cortical bone as well as bone structure (trabecular number or thickness or cortical porosity for instance).

RESULTS

A total of 26 patients were prospectively included. The mean age was 57.3 ± 12.1 years. The mean dialysis vintage was 27.5 ± 16.4 months before transplantation. Bone biomarkers showed a significant decrease at 3 months after transplantation. PTH decreased from 221.72 ng/L to 59.6 ng/L (P < 0.0001), P1NP from 211 ug/L to 72 ug/L (P < 0.013) and BLAP from 23 ug/L to 13 ug/L (P = 0.042). BMD was measured by DXA and HR-pQCT at 7 days [6; 8] and 102 days (90; 113) after transplantation. We observed a significant reduction of BMD by DXA at the hip site from 0.868 g/cm2 to 0.856 g/cm2 (P = 0.02), but not at the lumbar site. The HR-pQCT analysis demonstrated a significant reduction of the trabecular BMD from 152.62 mg HA/ccm to 150.80 mg HA/ccm (P < 0.0001) at the tibia site and from 159.09 mg HA/ccm to 156.25 mg HA/ccm (P < 0.0001) at the radius site. No change in bone structure have been observed at 3 months post-transplantation with the HR-pQCT analysis.

CONCLUSION

HR-pQCT is sensitive enough to show a significant decrease of BMD at the trabecular site, as soon as 3 months after transplantation compared to DEXA at the lumbar spine. However, no change in bone structure nor cortical bone volume has been observed. The sensibility of this technique might be higher than DEXA. The rapid assessment of bone structure (3 months post-transplantation) might be too soon to evaluate such abnormalities. Detecting properly rapid changes in bone density, as soon as 3 months after renal transplantation seems feasible. The impact on bone health management needs to be further studied.

[Diagnosis and management of renal allograft rejection]

Renal allograft rejection involves many mechanisms of innate and adaptive immunity, responsible for parenchymal inflammatory lesions that negatively impact the long-term outcomes of the renal allograft. The heterogeneous presentations of rejections in terms of clinical, biological and histological aspects make them difficult to manage in daily clinical practice. Indeed, current therapeutic strategies are disappointing in term of long-term outcomes, including graft survival. In this article, we will discuss the main effector mechanisms of rejection and their histological classification, as well as the existing treatments and those currently under evaluation.

The MHC class I MICA gene is a histocompatibility antigen in kidney transplantation

The identity of histocompatibility loci, besides human leukocyte antigen (HLA), remains elusive. The major histocompatibility complex (MHC) class I MICA gene is a candidate histocompatibility locus. Here, we investigate its role in a French multicenter cohort of 1,356 kidney transplants. MICA mismatches were associated with decreased graft survival (hazard ratio (HR), 2.12; 95% confidence interval (CI): 1.45–3.11; P < 0.001). Both before and after transplantation anti-MICA donor-specific antibodies (DSA) were strongly associated with increased antibody-mediated rejection (ABMR) (HR, 3.79; 95% CI: 1.94–7.39; P < 0.001; HR, 9.92; 95% CI: 7.43–13.20; P < 0.001, respectively). This effect was synergetic with that of anti-HLA DSA before and after transplantation (HR, 25.68; 95% CI: 3.31–199.41; P = 0.002; HR, 82.67; 95% CI: 33.67–202.97; P < 0.001, respectively). De novo-developed anti-MICA DSA were the most harmful because they were also associated with reduced graft survival (HR, 1.29; 95% CI: 1.05–1.58; P = 0.014). Finally, the damaging effect of anti-MICA DSA on graft survival was confirmed in an independent cohort of 168 patients with ABMR (HR, 1.71; 95% CI: 1.02–2.86; P = 0.041). In conclusion, assessment of MICA matching and immunization for the identification of patients at high risk for transplant rejection and loss is warranted.

Analysis of a multicenter cohort of kidney transplants shows that mismatches in the MICA locus and the presence of anti-MICA donor-specific antibodies are associated with reduced graft survival and increased rejection.

Age-adapted percentiles of measured glomerular filtration in healthy individuals: extrapolation to living kidney donors over 65 years

OBJECTIVES

Most data on glomerular filtration rate (GFR) originate from subjects <65 years old, complicating decision-making in elderly living kidney donors. In this retrospective multi-center study, we calculated percentiles of measured GFR (mGFR) in donors <65 years old and extrapolated these to donors ≥65 years old.

METHODS

mGFR percentiles were calculated from a development cohort of French/Belgian living kidney donors <65 years (n=1,983), using quantiles modeled as cubic splines (two linear parts joining at 40 years). Percentiles were extrapolated and validated in an internal cohort of donors ≥65 years (n=147, France) and external cohort of donors and healthy subjects ≥65 years (n=329, Germany, Sweden, Norway, France, The Netherlands) by calculating percentages within the extrapolated 5th-95th percentile (P5-P95).

RESULTS

Individuals in the development cohort had a higher mGFR (99.9 ± 16.4 vs. 86.4 ± 14 and 82.7 ± 15.5 mL/min/1.73 m²) compared to the individuals in the validation cohorts. In the internal validation cohort, none (0%) had mGFR below the extrapolated P5, 12 (8.2%) above P95 and 135 (91.8%) between P5-P95. In the external validation cohort, five subjects had mGFR below the extrapolated P5 (1.5%), 25 above P95 (7.6%) and 299 (90.9%) between P5-P95.

CONCLUSIONS

We demonstrate that extrapolation of mGFR from younger donors is possible and might aid with decision-making in elderly donors.

[Organ transplantation during SARS-CoV-2 epidemic : the 2020-2021 Liege transplant Center experience]

The «Severe Acute Respiratory Syndrome coronavirus 2» (SARS-CoV-2) pandemic has disrupted medical care and intra-hospital organization during 2020, both in Belgium and throughout the world. Solid organ transplantation was not spared and in Belgium, the number of organ donors and transplants overall decreased by 20 % for livers and by 33 % for hearts between 2019 and 2020. The aim of this article is to summarize the experience acquired in 2020 and 2021 on the organizational and medical implications of the coronavirus disease 2019 (COVID-19) pandemic with regard to the care of patients transplanted or awaiting for organ transplants, and to draw conclusions both for the aftermath of COVID-19 but also for future pandemics. Vaccination against SARS-CoV-2 is highly recommended and particularly important in organ transplant recipients, even if the response rate is lower than in the non-transplanted population. A third injection is now advised in immunosuppressed patients.

[18F]FDG PET/CT imaging disproves renal allograft acute rejection in kidney transplant recipients with acute kidney dysfunction: a validation cohort

PURPOSE

[¹⁸F]FDG PET/CT may predict the absence of acute allograft rejection (AR) in kidney transplant recipients (KTRs) with acute kidney injury (AKI). Still, the proposed threshold of 1.6 of the mean of mean standardized uptake values (mSUVmean) in the renal parenchyma needs validation.

METHODS

We prospectively performed 86 [¹⁸F]FDG PET/CT in 79 adult KTRs who underwent per-cause transplant biopsy for suspected AR. Biopsy-proven polyoma BK nephropathies (n = 7) were excluded. PET/CT was performed 192 ± 18 min after administration of 254.4 ± 30.4 MBq of [¹⁸F]FDG. The SUV_mean was measured in both upper and lower poles of the renal allograft. One-way analysis of variance (ANOVA) and Tukey's studentized range test were sequentially performed. The receiver operating characteristic (ROC) curve was drawn to discriminate "AR" from non-pathological ("normal" + "borderline") conditions.

RESULTS

The median age of the cohort was 55 [43; 63] years, with M/F gender ratio of 47/39. The mean eGFR was 31.9 ± 14.6 ml/min/1.73m². Biopsies were categorized in 4 groups: "normal" (n = 54), "borderline" (n = 9), "AR" (n = 14), or "others" (n = 2). The median [min; max] mSUV_mean reached 1.72 [1.02; 2.07], 1.97 [1.55; 2.11], 2.13 [1.65, 3.12], and 1.84 [1.57; 2.12] in "normal," "borderline," "AR," and "others" groups, respectively. ANOVA demonstrated a significant difference of mSUV_mean among groups (F = 13.25, p < 0.0001). The ROC area under the curve was 0.86. Test sensitivity and specificity corresponding to the threshold value of 1.6 were 100% and 30%, respectively.

CONCLUSION

[¹⁸F]FDG PET/CT may help noninvasively prevent inessential transplant biopsies in KTR with AKI.

MO939RECURRENCE AND OUTCOME OF ANTI-GLOMERULAR BASEMENT MEMBRANE GLOMERULONEPHRITIS AFTER KIDNEY TRANSPLANTATION: A BELGIAN MULTICENTER STUDY

Background and Aims

Recurrence of anti-glomerular basement membrane (anti-GBM) glomerulonephritis in the kidney graft is a rare event, described in limited case reports and registry analysis. The aim of this study was to evaluate in a large cohort of patients with detailed data collection and long follow-up the risk of recurrence of anti-GBM disease and graft loss caused by recurrence, the risk factors associated with clinical recurrence and the long-term patient and graft survival.

Method

Multicenter retrospective study. Inclusion criteria: patients with anti-GBM glomerulonephritis transplanted with a kidney between 1977 and 2015. Exclusion criteria: systemic vasculitis (except ANCA), lupus erythematosus and cryoglobulinemia. Clinical recurrence was defined as reappearance of signs of glomerulonephritis along with histological signs of proliferative glomerulonephritis and linear IgG staining on kidney biopsy, with or without anti-GBM antibodies.

Results

Fifty-three patients were included. Clinical recurrence in a first kidney transplant occurred in only one patient five years after transplantation -a prevalence rate of 1.9%- in the context of cessation of immunosuppressive drugs. The graft was lost due to recurrence. Histological recurrence with linear IgG staining on kidney biopsy in the absence of histologic signs of proliferative glomerulonephritis was observed in four patients, in the context of cellular rejection. Two patients lost their kidney graft from severe acute rejection; the others fully recovered. Patient survival was 100%, 94% and 89% at 5, 10 and 15 years, respectively. Overall, death-censored first graft survival rates were 88%, 83% and 79% at 5, 10 and 15 years, respectively.

Conclusion

Recurrence rate of anti-GBM glomerulonephritis after transplantation is very low, and associated with graft loss. The long-term patient and graft survival rates are excellent.

FC 055PERCENTILES OF NORMAL MEASURED GLOMERULAR FILTRATION RATE BASED ON DATA FROM LIVING KIDNEY DONORS

Background and Aims

Studies of healthy individuals or candidates for living kidney donation, in various geographical areas and ethnic groups, describe a decline of glomerular filtration rate (GFR) with age. Most data on GFR are obtained from subjects in the general population or from candidates for kidney donation who are younger than 65 years. It is currently unknown whether the definition of normal GFR in subjects older than 65 years is similar to the definition in those younger than 65 years. Because the age of candidates for living kidney donation is increasing worldwide, lack of GFR references for older donors complicates the selection process. Moreover, older individuals are most likely to have a mildly decreased GFR that may be misinterpreted as chronic kidney disease. In this study, we calculated percentiles of measured GFR (mGFR) from a large cohort of effective kidney donors (EKD) younger than 65 years, and extrapolated them to subjects older than 65 years. Additionnaly, we collected mGFR data from different centers within Europe from EKD and/or healthy people (HP) from the general population older than 65 years. We tested if the distribution of mGFR of these older subjects fitted with the extrapolated percentiles.

Method

In this retrospective, observational, multi-center study, percentiles of mGFR in EKD were calculated from a development cohort of French and Belgian EKD younger than 65 years (n=1983). From the French kidney donor study, 147 EKD older than 65 years were considered as the internal validation cohort. In an external validation cohort, data on mGFR of subjects older than 65 years, either EKD or HP from the general population (from Germany, Sweden (2), Norway, Netherlands and France, n=2459) were included. Data were fully anonymized and this retrospective study was approved by the respective ethics committees. Percentiles were derived for the development database, using quantiles modeled as cubic splines with two linear parts joining at one age-knot of 40 years. The median quantile had a constant first part (slope of zero) and a second part with a negative slope of -0.88235 mL/min/1.73m² per year. To maintain consistency, all quantiles were adjusted to show the same shape as the medium quantile. Above 65 years, the percentile values were extrapolated using the same mathematical model. We then calculated the percentage of results from the internal and external validation cohorts that were within the 5th extrapolated percentile (P5) and 95th percentile (P95). A sensitivity analysis including the EKD only was performed.

Results

Individuals in the development cohort were younger than in the internal or external validation cohort (47.3±10.5 years vs. 68.8±2.9 years and 71.4±6.4 years; respectively, both p&lt;0.001). Individuals in the development cohort had a higher mGFR than in the internal or external validation cohort (99.9±16.4 mL/min/1.73m2 vs. 86.4±14 mL/min/1.73m2 and 82.7±15.5 mL/min/1.73m2; respectively, both p &lt; 0.001). Among the 147 EKD from the internal validation cohort, none (0%) had mGFR below the extrapolated P5 and12 (8.1%) had mGFR higher than the extrapolated P95. Consequently, 135/147 (91.2%) of subjects were between P5-P95. (Figure 1). Considering the whole external validation cohort (n=329), 5 subjects had mGFR lower than extrapolated P5 (1.5%), 25 were above P95, leaving 299 (90.9%) with mGFR between P5 and the extrapolated P95.

Conclusion

We demonstrate that extrapolated percentiles of mGFR (calculated in individuals younger than 65) fits well with the distribution of mGFR in individuals older than 65. Extrapolation of percentiles to individuals older than 65 is useful to define age-adapted GFR thresholds for older individuals.

FC 121THE UPTAKE OF PET RADIOTRACER 18 F-FLUORODEOXYGLUCOSE BY THE RENAL ALLOGRAFT SIGNIFICANTLY CORRELATES WITH THE ACUTE BANFF SCORES OF CORTEX INFLAMMATION

Background and Aims

Acute T-cell mediated rejection (TCMR) is associated with the recruitment of mononuclear leukocytes into the renal transplant, which corresponds to the core of the conventional Banff classification. The boosted metabolism of these inflammatory cells can be assessed by positron emission tomography (PET) quantifying the renal uptake of 18F-fluorodeoxyglucose (18FDG). The correlation of biopsy-based Banff versus PET-based scores of acute inflammation in the renal transplant is unknown.

Method

From January 2013 to December 2019, we prospectively performed 114 18FDG-PET/CT in 105 adult KTR who underwent per cause transplant biopsy for suspected TCMR. Biopsy-proven polyoma-BK nephropathies (n=7) and uninterpretable PET images (n=2) were excluded. PET/CT was performed 194±19 minutes after administration of 243±35 MBq of 18FDG, before any immunosuppression change. The mSUVs were measured in both upper and lower poles of the renal allograft. The acute Banff score was conventionally defined as the sum (from 0 to 15) of g (glomerulitis), ptc (peritubular capillaritis), t (tubulitis), i (inflammation in non-scarred cortex) and v (endarteritis). The Banff “total i” score (from 0 to 3) corresponds to the total cortical inflammation, including scarred and non-scarred cortex. Regression of mSUV against the acute Banff score was performed, and Pearson correlation coefficients were calculated. The distribution of mSUV between “total i” groups was assessed by the non-parametric Kruskal-Wallis test followed by Dunn’s post hoc test.

Results

The mean age of the cohort was 51.5±14.3 years, with M/F ratio of 67/38. The prevalence of biopsy-proven TCMR and borderline was 20.9% and 16.2%, respectively. The mean mSUV of the 105-case cohort was 1.82±0.45. The highest value of acute Banff score was 12, while 55.2% of biopsies were scored as 0. The distribution of “Total i” score was: 0 (58.8%); 1 (20.6%); 2 (8.8%); 3 (11.8%). Regression showed a significant correlation between mSUV and acute Banff score (p&lt;0.0001), with adjusted R² of 0.38. The mSUV value was significantly different between subgroups of “Total i” (p, 0.0047), with 2.33±0.76 in score 3 versus 1.68±0.24 in score 1.

Conclusion

18FDG-PET/CT may help noninvasively assess the degree of allograft inflammation in KTR with suspected TCMR.

Recurrence and Outcome of Anti-Glomerular Basement Membrane Glomerulonephritis After Kidney Transplantation

Introduction

Recurrence of anti-glomerular basement membrane (anti-GBM) glomerulonephritis in the kidney graft is a rare event, described in limited reports. The aim of this study was to evaluate, in a large cohort of patients with long follow-up, the risk of recurrence of anti-GBM disease, the risk factors associated with clinical recurrence, and the long-term patient and graft survival.

Methods

This was a multicenter retrospective study. Inclusion criteria were patients with anti-GBM glomerulonephritis who underwent transplantation of a kidney between 1977 and 2015. Exclusion criteria were systemic vasculitis, lupus erythematosus, and cryoglobulinemia. Recurrence was defined as reappearance of clinical signs of glomerulonephritis along with histological signs of proliferative glomerulonephritis and linear IgG staining on kidney biopsy, with or without anti-GBM antibodies.

Results

A total of 53 patients were included. Recurrence of anti-GBM glomerulonephritis in a first kidney transplant occurred in only 1 patient 5 years after transplantation (a prevalence rate of 1.9%) in the context of cessation of immunosuppressive drugs, and resulted in graft loss due to recurrence. Linear IgG staining on kidney biopsy in the absence of histological signs of proliferative glomerulonephritis was observed in 4 patients, in the context of cellular rejection. Patient survival was 100%, 94%, and 89% at 5, 10, and 15 years, respectively. Death-censored first-graft survival rates were 88%, 83%, and 79% at 5, 10, and 15 years, respectively.

Conclusion

The recurrence rate of anti-GBM glomerulonephritis after transplantation is very low but is associated with graft loss. The long-term patient and graft survival rates are excellent.

Diagnostic yield of 18 F-FDG PET/CT imaging and urinary CXCL9/creatinine levels in kidney allograft subclinical rejection

Subclinical kidney allograft acute rejection (SCR) corresponds to "the unexpected histological evidence of acute rejection in a stable patient." SCR detection relies on surveillance biopsy. Noninvasive approaches may help avoid biopsy-associated complications. From November 2015 to January 2018, we prospectively performed positron emission tomography/computed tomography (PET/CT) after injection of F¹⁸ -fluorodeoxyglucose (¹⁸ F-FDG) in adult kidney transplant recipients with surveillance biopsy at ~3 months posttransplantation. The Banff-2017 classification was used. The ratio of the mean standard uptake value (mSUVR) between kidney cortex and psoas muscle was measured. Urinary levels of CXCL-9 were concomitantly quantified. Our 92-patient cohort was categorized upon histology: normal (n = 70), borderline (n = 16), and SCR (n = 6). No clinical or biological difference was observed between groups. The mSUVR reached 1.87 ± 0.55, 1.94 ± 0.35, and 2.41 ± 0.54 in normal, borderline, and SCR groups, respectively. A significant difference in mSUVR was found among groups. Furthermore, mSUVR was significantly higher in the SCR vs normal group. The area under the receiver operating characteristic curve (AUC) was 0.79, with 83% sensitivity using an mSUVR threshold of 2.4. The AUC of urinary CXCL-9/creatinine ratios comparatively reached 0.79. The mSUVR positively correlated with ti and acute composite Banff scores. ¹⁸ F-FDG-PET/CT helps noninvasively exclude SCR, with a negative predictive value of 98%. External validations are required.

[Current and new therapeutic options in inborn errors of metabolism]

Inborn errors of metabolism (IEM) represent a vast group of orphan genetic disorders associated with enzyme deficiencies, substrates accumulation and products depletion. For several decades, the cornerstone of life-saving therapies in IEM was based on extreme manipulations of the nutritional intakes. Such outstanding dietary engineering is still relevant today, but new therapeutic avenues have emerged last years, based on better pathophysiological understanding and technological advances. In this paper, we summarize current and new therapeutic options in the field of IEM.

Observer variability in the assessment of renal 18F-FDG uptake in kidney transplant recipients

¹⁸F-FDG PET/CT imaging may help non-invasively disprove the diagnosis of acute kidney allograft rejection (AR) in kidney transplant recipients (KTR). The present study aims at evaluating the repeatability and reproducibility of the quantification of renal ¹⁸F-FDG uptake in KTR. We prospectively performed ¹⁸F-FDG PET/CT in 95 adult KTR who underwent surveillance transplant biopsy between 3 to 6 months post transplantation. Images were obtained 180 minutes after injecting 3 MBq ¹⁸F-FDG per kg body weight. Mean standard uptake value (SUV_mean) of kidney cortex was independently measured by 2 experienced observers in 4 volumes of interest (VOI) distributed in the upper (n = 2) and lower (n = 2) poles. The first observer repeated SUV assessment in the uppermost VOI, blinded to the initial results. Intra-class correlation coefficients (ICC) and Bland-Altman plots were calculated. An ICC of 0.96 with 95%CI of [0.94; 0.97] was calculated for the intra-observer measurements. The ICC for inter-observer reproducibility for each VOI was 0.87 [0.81–0.91], 0.87 [0.81–0.91], 0.85 [0.78–0.89] and 0.83 [0.76–0.88] for the upper to the lower renal poles, respectively. The repeatability and reproducibility of the quantification of kidney allograft ¹⁸F-FDG uptake are both consistent, which makes it transferrable to the clinical routine.

"Acute kidney dysfunction with no rejection" is associated with poor renal outcomes at 2 years post kidney transplantation

Background

“Acute kidney dysfunction with no rejection” (ADNR) corresponds to acute kidney injury without histological evidence of acute rejection (AR) in kidney transplant recipients (KTR). The prognosis of ADNR is unknown.

Methods

From 2007 to 2015, we categorized KTR with for-cause kidney biopsy within the first 12 months post kidney transplantation (KTx) into ADNR (n = 93) and biopsy-proven AR (n = 22). Controls (C, n = 135) included KTR with no ADNR or AR within the first 24 months post-KTx. A piecewise linear regression with a single fixed-knot at 12 months served to establish intercepts and slopes of MDRD-eGFR variations from 12 to 24 months. The percentage of KTR with ≥30% reduction of eGFR from 12 to 24 months was calculated as a surrogate marker of future graft loss.

Results

The median time for for-cause biopsy was 22 [10–70] and 13 [7–43] days for ADNR and AR, respectively. At 12 months, eGFR was significantly higher in C (57.6 ± 14.9 mL/min/1.73m²) vs. ADNR (43.5 ± 15.4 mL/min/1.73m², p < 0.0001) and vs. AR (46.5 ± 15.2 mL/min/1.73m², p < 0.0065). The proportion of KTR with ≥30% reduction in eGFR from 12 to 24 months reached 16.3% in C vs. 29.9% in ADNR (p = 0.02) and vs. 15% in AR (not significant).

Conclusions

ADNR is associated with poor outcomes within 2 years post-KTx.

[18F-FDG positron emission tomography in non-oncological renal pathology: Current indications and perspectives]

Positron emission tomography combined with computed tomography (PET/CT) is a nuclear imaging technique which provides anatomical and functional information. PET/CT is increasingly used in non-oncological nephrology since conventional radiological approaches after injection of contrast agents are relatively contra-indicated in patients with chronic kidney disease (CKD). PET/CT after i.v. injection of ¹⁸F-fluoro-deoxy-glucose (FDG) is not toxic and is characterized by a high sensitivity. The level of irradiation (∼5mSv) is acceptable. CKD does not significantly influence tissue uptake of ¹⁸F-FDG. The purpose of the present review aims at detailing the non-oncological indications of ¹⁸F-FDG PET/CT in general nephrology and after kidney transplantation. Particularly, ¹⁸F-FDG PET/CT appears useful in the diagnosis of cyst infection in patients with autosomal dominant polycystic kidney disease, as well as in the characterization of retroperitoneal fibrosis. In kidney transplant recipients, ¹⁸F-FDG PET/CT may help in the diagnostic work-up of suspected acute rejection, thereby eventually avoiding unnecessary kidney transplant biopsy. Perspectives in ¹⁸F-FDG PET/CT imaging are discussed, including innovative approaches of image analysis.

Prospective randomized study of conversion from tacrolimus to cyclosporine A to improve glucose metabolism in patients with posttransplant diabetes mellitus after renal transplantation

Tacrolimus (TAC) increases the risk of posttransplant diabetes (PTDM) compared with cyclosporine A (CYC). The present 12-month, multicenter, investigator-driven, prospective, randomized study was designed to assess whether conversion from tacrolimus to CYC can reverse PTDM after renal transplantation. Predominantly white patients with PTDM according to the 2005 American Diabetes Association criteria were randomized to either replacement of TAC with CYC or continuation of their TAC-based regimen after stratification for type of glucose-lowering therapy, steroid therapy, and hepatitis C status. At 12 months, 14 of 41 patients with complete data in the CYC arm (34%; 95%CI 19%-49%) were free of diabetes, whereas this was the case in only 4 of 39 patients (10%; 95%CI 3%-20%) in the TAC arm (P = .01). At 12 months, 39% of patients in the CYC arm were off glucose-lowering medication vs 13% of patients in the TAC arm (P = .01). The CYC group decreased glycated hemoglobin level during the 12-month follow-up, resulting in significantly lower levels compared with the TAC group (6.0 ± 0.9% vs 7.1 ± 1.7% at 12 months; P = .002). In conclusion, replacement of TAC with CYC significantly improves glucose metabolism and has the potential to reverse diabetes during the first year after conversion. (EU Clinical Trials Register No. 2006-001765-42).

Controversies in the management of the haemodialysis-related arteriovenous fistula following kidney transplantation

Arteriovenous fistula (AVF) is regarded as the best vascular access for chronic haemodialysis (HD). Still, AVF inherently causes significant haemodynamic changes. Although the necessity for vascular access despite its putative cardiovascular complications favours AVF creation in patients under chronic HD, one may question whether sustaining a functional AVF after successful kidney transplantation extends the haemodynamic threat. Small prospective series suggest that AVF ligation causes rapid and sustained reduction in left ventricular hypertrophy. Still, the benefits of such a cardiac remodelling in long-terms of cardiovascular morbi-mortality still need to be proven. Furthermore, the elevation of diastolic blood pressure and arterial stiffness caused by AVF ligation may blunt the expected cardio-protection. Finally, the closure of a functioning AVF may accelerate the decline of kidney graft function. As a whole, the current management of a functioning AVF in kidney transplant recipients remains controversial and does not rely on strong evidence-based data. The individual risk of graft dysfunction and a return to chronic HD also needs to be balanced. Careful pre-operative functional assessments, including cardio-pulmonary testing and estimated glomerular filtration rate slope estimation, may help better selection of who might benefit the most from AVF closure. Large-scale prospective, ideally multi-centric, trials are essentially needed.

The closure of arteriovenous fistula in kidney transplant recipients is associated with an acceleration of kidney function decline

Background

The creation of arteriovenous fistula (AVF) may retard chronic kidney disease progression in the general population. Conversely, the impact of AVF closure on renal function in kidney transplant recipients (KTRs) remains unknown.

Methods

From 2007 to 2013, we retrospectively categorized 285 KTRs into three groups: no AVF (Group 0, n = 90), closed AVF (Group 1, n = 114) and left-open AVF (Group 2, n = 81). AVF closure occurred at 653 ± 441 days after kidney transplantation (KTx), with a thrombosis:ligation ratio of 19:95. Estimated glomerular filtration rate (eGFR) was determined using the Modification of Diet in Renal Disease equation. Linear mixed models calculated the slope and intercept of eGFR decline versus time, starting at 3 months post-KTx, with a median follow-up of 1807 days (95% confidence interval 1665-2028).

Results

The eGFR slope was less in Group 1 (-0.081 mL/min/month) compared with Group 0 (-0.183 mL/min/month; P = 0.03) or Group 2 (-0.164 mL/min/month; P = 0.09). Still, the eGFR slope significantly deteriorated after (-0.159 mL/min/month) versus before (0.038 mL/min/month) AVF closure (P = 0.03). Study periods before versus after AVF closure were balanced to a mean of 13.5 and 12.5 months, respectively, with at least 10 observations per patient ( n = 99).

Conclusions

In conclusion, a significant acceleration of eGFR decline is observed over the 12 months following the closure of a functioning AVF in KTRs.

Age-dependent reference intervals for estimated and measured glomerular filtration rate

Background

Defining mean and reference intervals for glomerular filtration rate (GFR) has been the subject of only a limited number of studies and review articles, with contradicting statements about the mean. Normal measured GFR (mGFR) values of ∼120–130 mL/min/1.73 m² have long been the referenced values for young adults but seem to be too high according to recent studies. Reference intervals are difficult to define because of the age decline of GFR, which is also observed in healthy subjects. Little data are available for subjects >70 years of age.

Methods

Based on the reference intervals for serum creatinine (SCr) and the recently published full-age spectrum (FAS) equation, we define simple age-dependent equations for the reference limits of GFR. The mGFR of 633 living potential kidney donors was used to validate the new formulae that define the reference interval.

Results

The reference limits for estimated GFR (eGFR), calculated by entering the reference limits for SCr into the FAS equation closely correspond with published reference limits for mGFR. Of the mGFRs of potential living kidney donors, 97.2% lie between the newly defined reference limits for GFR.

Conclusion

SCr reference limits may serve to define age-dependent reference limits for eGFR and mGFR.

Non-invasive approaches in the diagnosis of acute rejection in kidney transplant recipients, part II: omics analyses of urine and blood samples

Kidney transplantation (KTx) represents the best available treatment for patients with end-stage renal disease. Still, the full benefits of KTx are undermined by acute rejection (AR). The diagnosis of AR ultimately relies on transplant needle biopsy. However, such an invasive procedure is associated with a significant risk of complications and is limited by sampling error and interobserver variability. In the present review, we summarize the current literature about non-invasive approaches for the diagnosis of AR in kidney transplant recipients (KTRs), including in vivo imaging, gene-expression profiling and omics analyses of blood and urine samples. Most imaging techniques, such as contrast-enhanced ultrasound and magnetic resonance, exploit the fact that blood flow is significantly lowered in case of AR-induced inflammation. In addition, AR-associated recruitment of activated leucocytes may be detectable by 18F-fluorodeoxyglucose positron emission tomography. In parallel, urine biomarkers, including CXCL9/CXCL10 or a three-gene signature of CD3ε, CXCL10 and 18S RNA levels, have been identified. None of these approaches has yet been adopted in the clinical follow-up of KTRs, but standardization of analysis procedures may help assess reproducibility and comparative diagnostic yield in large, prospective, multicentre trials.

Non-invasive approaches in the diagnosis of acute rejection in kidney transplant recipients. Part I. In vivo imaging methods

Kidney transplantation (KTx) represents the best available treatment for patients with end-stage renal disease. Still, full benefits of KTx are undermined by acute rejection (AR). The diagnosis of AR ultimately relies on transplant needle biopsy. However, such an invasive procedure is associated with a significant risk of complications and is limited by sampling error and interobserver variability. In the present review, we summarize the current literature about non-invasive approaches for the diagnosis of AR in kidney transplant recipients (KTRs), including in vivo imaging, gene expression profiling and omics analyses of blood and urine samples. Most imaging techniques, like contrast-enhanced ultrasound and magnetic resonance, exploit the fact that blood flow is significantly lowered in case of AR-induced inflammation. In addition, AR-associated recruitment of activated leukocytes may be detectable by ¹⁸F-fluoro-deoxy-glucose positron emission tomography. In parallel, urine biomarkers, including CXCL9/CXCL10 or a three-gene signature of CD3ε, IP-10 and 18S RNA levels, have been identified. None of these approaches has been adopted yet in the clinical follow-up of KTRs, but standardization of procedures may help assess reproducibility and compare diagnostic yields in large prospective multicentric trials.

Fluorodeoxyglucose F(18) Positron Emission Tomography Coupled With Computed Tomography in Suspected Acute Renal Allograft Rejection

Management of kidney transplant recipients (KTRs) with suspected acute rejection (AR) ultimately relies on kidney biopsy; however, noninvasive tests predicting nonrejection would help avoid unnecessary biopsy. AR involves recruitment of leukocytes avid for fluorodeoxyglucose F(18) ((18) F-FDG), thus (18) F-FDG positron emission tomography (PET) coupled with computed tomography (CT) may noninvasively distinguish nonrejection from AR. From January 2013 to February 2015, we prospectively performed 32 (18) F-FDG PET/CT scans in 31 adult KTRs with suspected AR who underwent transplant biopsy. Biopsies were categorized into four groups: normal (n = 8), borderline (n = 10), AR (n = 8), or other (n = 6, including 3 with polyoma BK nephropathy). Estimated GFR was comparable in all groups. PET/CT was performed 201 ± 18 minutes after administration of 3.2 ± 0.2 MBq/kg of (18) F-FDG, before any immunosuppression change. Mean standard uptake values (SUVs) of both upper and lower renal poles were measured. Mean SUVs reached 1.5 ± 0.2, 1.6 ± 0.3, 2.9 ± 0.8, and 2.2 ± 1.2 for the normal, borderline, AR, and other groups, respectively. One-way analysis of variance demonstrated a significant difference of mean SUVs among groups. A positive correlation between mean SUV and acute composite Banff score was found, with r(2)  = 0.49. The area under the receiver operating characteristic curve was 0.93, with 100% sensitivity and 50% specificity using a mean SUV threshold of 1.6. In conclusion, (18) F-FDG PET/CT may help noninvasively prevent avoidable transplant biopsies in KTRs with suspected AR.

Recommendations for donation after circulatory death kidney transplantation in Europe

Donation after circulatory death (DCD) donors provides an invaluable source for kidneys for transplantation. Over the last decade, we have observed a substantial increase in the number of DCD kidneys, particularly within Europe. We provide an overview of risk factors associated with DCD kidney function and survival and formulate recommendations from the sixth international conference on organ donation in Paris, for best-practice guidelines. A systematic review of the literature was performed using Ovid Medline, Embase and Cochrane databases. Topics are discussed, including donor selection, organ procurement, organ preservation, recipient selection and transplant management.

Activation of the calcium-sensing receptor before renal ischemia/reperfusion exacerbates kidney injury

Activation of the calcium-sensing receptor (CaSR) by ischemia/reperfusion (I/R) favours apoptosis in cardiomyocytes, hepatocytes and neurons. Its role in renal I/R is unknown. We investigated the impact of pharmacological preactivation of the CaSR on kidney structure and function in a murine model of bilateral renal 30-min ischemia and 48-hour reperfusion, and in a 6-year cohort of kidney transplant recipients (KTR). C57BL/6J mice were administered daily with CaSR agonist, R-568, or with vehicle for 48 hours. Evaluation of serum urea and creatinine levels, renal histology and urine metabolome by nuclear magnetic resonance showed that R-568 was not nephrotoxic per se. Following I/R, serum urea and creatinine levels increased higher in R-568-treated animals than in controls. Jablonski's score was significantly greater in R-568-treated kidneys, which showed a higher rate of cell proliferation and apoptosis in comparison to controls. Next, we retrospectively identified 36 patients (10.7% of our cohort) who were treated by CaSR agonist, cinacalcet, at the time of kidney transplantation (KTx). After matching these to 61 KTR upon type of donor, cold ischemic time, residual diuresis, and donor age, we observed that delayed graft function, i.e. need for dialysis in the first week after KTx, occurred in 42 and 23% of cinacalcet-treated and control groups, respectively (p≤0.05). These data suggest that pharmacological preactivation of the CaSR before renal I/R exacerbates kidney injury.

Clinical variability in neurohepatic syndrome due to combined mitochondrial DNA depletion and Gaucher disease

A 1-year-old girl born to consanguineous parents presented with unexplained liver failure, leading to transplantation at 19 months. Subsequent partial splenectomy for persistent cytopenia showed the presence of foamy cells, and Gaucher disease was confirmed by homozygosity for the p.Leu483Pro mutation in the GBA gene. She was treated by enzyme replacement therapy (ERT). Clinical follow-up showed mild developmental delay, strabismus, nystagmus and oculomotor apraxia. Biochemical studies revealed multiple respiratory chain deficiencies and a mosaic pattern of deficient complex IV immunostaining in liver and fibroblast. Molecular analysis identified a mtDNA depletion syndrome due to the homozygous p.Pro98Leu mutation in MPV17. A younger sister unaffected by mtDNA depletion, presented with pancytopenia and hepatosplenomegaly. ERT for Gaucher disease resulted in visceral normalization without any neurological symptom. A third sister, affected by both conditions, had marked developmental delay, strabismus and ophthalmoplegia but no liver cirrhosis. In conclusion, intrafamilal variability occurs in MPV17-related disease. The combined pathological effect of Gaucher and mitochondrial diseases can negatively impact neurological and liver functions and influence the outcome in consanguineous families. The immunocytochemical staining of OXPHOS protein in tissues and cultured cells is a powerful tool revealing mosaic pattern of deficiency pointing to mtDNA-related mitochondrial disorders.

Two novel mutations of the CLDN16 gene cause familial hypomagnesaemia with hypercalciuria and nephrocalcinosis

Familial hypomagnesaemia with hypercalciuria and nephrocalcinosis is an autosomal-recessive disease caused by mutations in the CLDN16 or CLDN19 genes, which encode tight junction-associated proteins, claudin-16 and -19. The resultant tubulopathy leads to urinary loss of Mg²⁺ and Ca²⁺, with subsequent nephrocalcinosis and end-stage renal disease (ESRD). An 18-year-old boy presented with chronic kidney disease and proteinuria, as well as hypomagnesaemia, hypercalciuria and nephrocalcinosis. A kidney biopsy revealed tubular atrophy, interstitial fibrosis and segmental sclerosis of some glomeruli. Two novel mutations in the CLDN16 gene were identified: c.340C>T (nonsense) and c.427+5G>A (splice site). The patient reached ESRD at 23 and benefited from kidney transplantation.

Mesenchymal stromal cell therapy in conditions of renal ischaemia/reperfusion

Acute kidney injury (AKI) represents a worldwide public health issue of increasing incidence, with a significant morbi-mortality. AKI treatment mostly relies on supportive manoeuvres in the absence of specific target-oriented therapy. The pathophysiology of AKI commonly involves ischaemia/reperfusion (I/R) events, which cause both immune and metabolic consequences in renal tissue. Similarly, at the time of kidney transplantation (KT), I/R is an unavoidable event which contributes to early graft dysfunction and enhanced graft immunogenicity. Mesenchymal stromal cells (MSCs) represent a heterogeneous population of adult, fibroblast-like multi-potent cells characterized by their ability to differentiate into tissues of mesodermal lineages. Because MSC have demonstrated immunomodulatory, anti-inflammatory and tissue repair properties, MSC administration at the time of I/R and/or at later times has been hypothesized to attenuate AKI severity and to accelerate the regeneration process. Furthermore, MSC in KT could help prevent both I/R injury and acute rejection, thereby increasing graft function and survival. In this review, summarizing the encouraging observations in animal models and in pilot clinical trials, we outline the benefit of MSC therapy in AKI and KT, and envisage their putative role in renal ischaemic conditioning.