Dynamics of HLA and angiotensin II type 1 receptor antibodies during pregnancy

BACKGROUND

Alloantibodies, especially anti-human leukocyte antigen antibodies (HLA antibodies), and autoantibodies, as angiotensin II type 1 receptor antibodies (AT1R antibodies), may complicate the access and the course of transplantation. Pregnancy is a known source of HLA antibodies, with most studies evaluating pregnancy-induced sensitization by complement-dependent cytotoxicity assays, mainly after childbirth. AT1R antibodies have been evaluated in the context of preeclampsia. We aimed to evaluate pregnancy as a natural source of HLA antibodies and AT1R antibodies, their dynamics along gestation and the potential factors involved in antibody appearance.

METHODS

Serum samples from pregnant women were collected during the three trimesters of pregnancy (1T, 2T, 3T). Presence of HLA antibodies was assessed by screening beads on Luminex and AT1R antibodies by ELISA.

RESULTS

A cohort of 138 pregnant women were included. Samples from all were tested in 1T, 127 in 2T and 102 in 3T. HLA antibodies increased from 29.7 % (1T) to 38.2 % (3T). AT1R antibodies were stable around 30 % along pregnancy. Up to 43.2 % multiparous women had HLA antibodies, with a similar proportion of class I and class II antibodies. In primiparous women HLA antibodies increased along pregnancy (from 17.6 % to 34.1 %), with predominance of class II HLA antibodies. AT1R antibodies were not different in primiparous and multiparous women.

CONCLUSIONS

Pregnancy is a relevant source of HLA antibodies sensitization, but not of AT1R antibodies. HLA antibodies increased clearly in primiparous women with predominance of class II. The use of newer solid-phase techniques on Luminex evidence a higher degree of HLA sensitization during pregnancy.

Isolation and characterization of exosome-enriched urinary extracellular vesicles from Dent's disease type 1 Spanish patients

BACKGROUND AND OBJECTIVES

Dent's disease type 1 (DD1) is a rare X-linked hereditary pathology caused by CLCN5 mutations that is characterized mainly by proximal tubule dysfunction, hypercalciuria, nephrolithiasis/nephrocalcinosis, progressive chronic kidney disease, and low-weight proteinuria, the molecular hallmark of the disease. Currently, there is no specific curative treatment, only symptomatic and does not prevent the progression of the disease. In this study we have isolated and characterized urinary extracellular vesicles (uEVs) enriched in exosomes that will allow us to identify biomarkers associated with DD1 progression and a better understanding of the pathophysiological bases of the disease.

MATERIALS AND METHODS

Through a national call from the Spanish Society of Nephrology (SEN) and the Spanish Society of Pediatric Nephrology (AENP), urine samples were obtained from patients and controls from different Spanish hospitals, which were processed to obtain the uEVS. The data of these patients were provided by the respective nephrologists and/or extracted from the RENALTUBE registry. The uEVs were isolated by ultracentrifugation, morphologically characterized and their protein and microRNA content extracted.

RESULTS

25 patients and 10 controls were recruited, from which the urine was processed to isolate the uEVs. Our results showed that the relative concentration of uEVs/mL is lower in patients compared to controls (0.26 × 106 uEVs/mL vs 1.19 × 106 uEVs/mL, p < 0.01). In addition, the uEVs of the patients were found to be significantly larger than those of the control subjects (mean diameter: 187.8 nm vs 143.6 nm, p < 0.01). Finally, our data demonstrated that RNA had been correctly extracted from both patient and control exosomes.

CONCLUSIONS

In this work we describe the isolation and characterization of uEVs from patients with Dent 1 disease and healthy controls, that shall be useful for the subsequent study of differentially expressed cargo molecules in this pathology.

Evolution of kidney allograft loss causes over 40 years (1979-2019)

INTRODUCTION

The improvement of kidney allograft recipient and graft survival showed a decrease over the last 40 years. Long-term graft loss rate remained stable during a 25-year time span. Knowing the changing causes and the risk factors associated with graft loss requires special attention. The present study aimed to assess the causes of graft loss and kidney allograft recipient death. Also, we aimed to compare two different periods (1979-1999 and 2000-2019) to identify changes in the characteristics of the failed allografts and recipient and donors profile.

METHODS AND PATIENTS

We performed a single-center cohort study. We included all the kidney transplant recipients at the Hospital del Mar (Barcelona) between May 1979 and December 2019. Graft loss was defined as recipient death with functioning graft and as loss of graft function (return to dialysis or retransplantation). We assessed the causes of graft loss using clinical and histological information. We also analyzed the results of the two different transplant periods (1979-1999 and 2000-2019).

RESULTS

Between 1979 and 2019, 1522 transplants were performed. The median follow-up time was 56 (IQR 8-123) months. During follow-up, 722 (47.5%) grafts were lost: 483 (66.9%) due to graft failure and 239 (33.1%) due to death with functioning graft. The main causes of death were cardiovascular (25.1%), neoplasms (25.1%), and infectious diseases (21.8%). These causes were stable between the two periods of time. Only the unknown cause of death has decreased in the last period. The main cause of graft failure (loss of graft function) was the allograft chronic dysfunction (75%). When histologic information was available, antibody-mediated rejection (ABMR) and interstitial fibrosis/tubular atrophy (IF/TA) were the most frequent specific causes (15.9% and 12.6%). Of the graft failures, 213 (29.5%) were early (<1 year of transplantation). Vascular thrombosis was the main cause of early graft failure in the second period (2000-2019) (46.7%) and T-cell-mediated rejection (TCMR) was the main cause (31.3%) in the first period (1979-1999). The causes of late graft loss were similar between the two periods.

CONCLUSIONS

The causes of kidney allograft recipient death are still due to cardiovascular and malignant diseases. Vascular thrombosis has emerged as a frequent cause of early graft loss in the most recent years. The evaluation of the causes of graft loss is necessary to improve kidney transplantation outcomes.

Microvascular inflammation in the absence of human leukocyte antigen-donor-specific antibody and C4d: An orphan category in Banff classification with cytotoxic T and natural killer cell infiltration

Isolated microvascular inflammation (iMVI) without HLA donor-specific antibodies or C4d deposition in peritubular capillaries remains an enigmatic phenotype that cannot be categorized as antibody-mediated rejection (ABMR) in recent Banff classifications. We included 221 kidney transplant recipients with biopsies with ABMR (n = 73), iMVI (n = 32), and normal (n = 116) diagnoses. We compared peripheral blood leukocyte distribution by flow cytometry and inflammatory infiltrates in kidney transplant biopsies among groups. Flow cytometry showed fewer lymphocytes and total, CD4+, and CD8+ peripheral T cells in iMVI compared with ABMR and normal cases. ABMR and iMVI had fewer total natural Killer (NK) cells but more NKG2A+ NK cells. Immunohistochemistry indicated that ABMR and iMVI had greater CD3+ and CD68+ glomerular infiltration than normal biopsies, whereas CD8+ and TIA1+ cells showed only increased iMVI, suggesting they are cytotoxic T cells. Peritubular capillaries displayed more CD3+, CD56+, TIA1+, and CD68+ cells in both ABMR and iMVI. In contrast, iMVI had less plasma cell infiltration in peritubular capillaries and interstitial aggregates than ABMR. iMVI displayed decreased circulating T and NK cells mirrored by T cell and NK cell infiltration in the renal allograft, similar to ABMR. However, the lesser plasma cell infiltration in iMVI may suggest an antibody-independent underlying stimulus.

Clinical and genetic characteristics of Dent's Disease type 1 in Europe

Background

Dent's disease type 1 (DD1) is a rare X-linked nephropathy caused by CLCN5 mutations, characterized by proximal tubule dysfunction, including low-molecular-weight proteinuria (LMWP), hypercalciuria, nephrolithiasis-nephrocalcinosis, progressive chronic kidney disease (CKD) and kidney failure (KF). Current management is symptomatic and does not prevent disease progression. Here we describe the contemporary DD1 picture across Europe to highlight its unmet needs.

Methods

A physician-based anonymous international e-survey supported by several European Nephrology Networks/Societies was conducted. Questions focused on DD1 clinical features, diagnostic procedure and mutation spectrum.

Results

Two-hundred seven DD1 male patients were reported, being clinical data available for 163 with confirmed CLCN5 mutations. Proteinuria was the most common leading manifestation (49.1%). During follow-up, all patients showed LMWP, 66.4% nephrocalcinosis, 44.4% hypercalciuria and 26.4% nephrolithiasis. After 5.5 years, ∼50% of patients presented renal dysfunction, 20.7% developed CKD ≥ 3, and 11.1% KF. At last visit, hypercalciuria was more frequent in pediatric patients than in adults (73.4% vs. 19.0%). Conversely, nephrolithiasis, nephrocalcinosis and renal dysfunction were more prominent in adults. Furthermore, CKD progressed with age. Despite no clear phenotype/genotype correlation was observed, decreased glomerular filtration rate was more frequent in subjects with CLCN5 mutations affecting the pore or CBS domains compared to those with early-stop mutations.

Conclusions

Results from this large DD1 cohort confirm previous findings and provide new insights regarding age and genotype impact on CKD progression. Our data strongly support that DD1 should be considered in male patients with CKD, nephrocalcinosis/hypercalciuria and non-nephrotic proteinuria and provide additional support for new research opportunities.

Increased mortality after kidney transplantation in mildly frail recipients

Background

Physical Frailty Phenotype (PFP) is the most used frailty instrument among kidney transplant recipients, classifying patients as pre-frail if they have 1–2 criteria and as frail if they have ≥3. However, different definitions of robustness have been used among renal patients, including only those who have 0 criteria, or those with 0–1 criteria. Our aim was to determine the impact of one PFP criterion on transplant outcomes.

Methods

We undertook a retrospective study of 296 kidney transplant recipients who had been evaluated for frailty by PFP at the time of evaluating for transplantation.

Results

Only 30.4% of patients had 0 criteria, and an additional 42.9% showed one PFP criterion. As PFP score increased, a higher percentage of women and cerebrovascular disease were found. Recipients with 0–1 criteria had lower 1-year mortality after transplant than those with ≥2 (1.8% vs 10.1%), but this difference was already present when we only considered those who scored 0 (mortality 1.1%) and 1 (mortality 2.4%) separately. The multivariable analysis confirmed that one PFP criterion was associated to a higher risk of patient death after kidney transplantation [hazard ratio 3.52 (95% confidence interval 1.03–15.9)].

Conclusions

Listed kidney transplant candidates frequently show only one PFP frailty criterion. This has an independent impact on patient survival after transplantation.

MO991: Covid-19 Infection After Kidney Transplantation in Spain: Comparable Impact Throughout Six Epidemic Waves

BACKGROUND AND AIMS

The successive COVID-19 epidemic waves have significantly influenced kidney transplantation (KT) programs. Contact protection together with vaccination are the principal protective tools for KT recipients. We reviewed the impact of COVID-19 infection in KT recipients throughout the different epidemic waves.

METHOD

Of 900 active KT recipients in our program, 160 (17.8%) have suffered COVID-19 infection during the six epidemic waves: first (March–August 2020), second (September–December2020), third (January–March 2021), fourth (April–May 2021), fifth (June–September 2021) and sixth (October–December 2021, preliminary data). We compared the clinical evolution and the impact of vaccination.

RESULTS

Infected KT recipients were younger in the third and fourth waves (P  &lt; 0.001). We observed a higher percentage of pneumonia and hospital admission in the first and fifth waves (P = 0.045, P = 0.016) (Table 1), without differences in ICU admission, and with the disappearance of asymptomatic cases after the third wave. The highest mortality was observed in KT recipients &gt;65 years old infected within the first 6 months after KT (P = 0.006) and overall mortality was higher in the first wave (P = 0.033). Mortality in hospitalized KT recipients and those admitted in the ICU were similar along the 5 waves, without clear impact of vaccination (P = 0.251). On the 5 January 2022, we have already accumulated an incidence of COVID in KT of 3.1% (sixth wave, 77% with booster vaccination), similar to the first wave (3.8%), with 12.5% mortality, similar to second, third and fifth waves, in patients with outcome (53.3%).

CONCLUSION

The incidence of COVID-19 in KT recipients has been high in all the waves of the pandemic in Spain. Global mortality has diminished after the first wave, and the time until outcome has increased. The highest mortality occurs in the subgroup of old KT recipients early after KT. Vaccination has not significantly reduced the mortality in KT with Covid who require hospital or ICU admission.

MO984: Increased Mortality After Kidney Transplantation in Mildly Frail Recipients: Need for Pretransplant Intervention

BACKGROUND AND AIMS

Frailty is associated with a higher rate of complications and mortality after kidney transplantation (KT). Physical frailty phenotype (PFP) is the most used frailty instrument among KT recipients, it comprises five criteria and classifies patients as frail if they have ≥3. We aimed to determine the impact of scoring 1 PFP criterion (mild frailty) on transplant outcomes.

METHOD

We have prospectively followed 449 KT candidates evaluated for frailty by PFP at the time of inclusion on the KT waiting list. Patients were classified as follows: 0, robust; 1, pre-frail-1; 2, pre-frail-2; and ≥3, frail. A prospective longitudinal study was performed in all patients in the cohort who underwent KT. Clinical outcomes and survival after transplantation according to frailty status at listing was assessed.

RESULTS

About 71.3% of total listed cohort resulted to be pre-frail (one criterion 41%, two criteria 19.8%) or frail (10.5%). Disparities were observed between sexes, with 5.2% of men and 21.9% of women being frail (P  &lt; 0.01). During the study period (median 26 months [IQR 16–39]), 296 patients got a KT and 153 remained listed. Patients who did not get transplanted were more frequently frail (16.3 versus 7.4%, P = 0.013). Frail patients had more hospital admissions during the first year after listing (43.4% if PFP ≥1 versus 20.8% if PFP = 0) and more cardiovascular events or major infectious events. In a multivariate model including only patients scoring 0 (robust) or prefail-1-criterion (n = 217), older age, previous cerebrovascular disease, peripheral vascular disease and mild pre-frailty were independent risk factors for mortality after KT (Figure 1).

CONCLUSION

Frailty is frequent in KT candidates, more frequent in women than men. Frail patients have less chances to receive a KT. KT candidates are frequently listed with one (out of five) frailty criterion, and this has an independent impact on patient survival after KT. A pre-transplant clinical framework for multimodal prehabilitation interventions to mitigate the effects of frailty and poor fitness after KT may be justified even in mildly pre-frail candidates.

FC 109: Microvascular Inflammation in Kidney Transplant Biopsies in the Absence of HLA-DSA Displays Intense Cytotoxic T-Cell and NK Cell but not Plasma Cell Infiltration

BACKGROUND AND AIMS

Microvascular inflammation (MVI) without evidence of HLA-donor-specific antibodies (HLA-DSA) or C4d+ deposition remains an enigmatic phenotype, which cannot be classified as antibody-mediated rejection (ABMR) according to recent Banff classifications. We aimed to compare peripheral blood lymphocyte (PBL) distribution and infiltrating immune cells in kidney transplant (KT) biopsies presenting MVI (g + ptc ≥ 2) without C4d+ and HLA-DSA, ABMR and normal histology to explore the role of immune cells in these entities.

METHODS

A total of 221 allograft biopsies with ABMR (n = 73), MVI (n = 32) and normal (n = 116) diagnoses were analysed.

RESULTS

MVI patients showed a decrease in the absolute number of T-cells compared with ABMR and normal cases (P = 0.020 and P = 0.006) due to a significant decrease of CD4+ T-cells compared to normal cases (P = 0.013) and a reduction of CD8+ T-cells compared with ABMR (P = 0.029). ABMR and MVI presented a lower absolute number of circulating Natural Killer (NK) cells than normal cases. Immunohistochemistry assessment was performed in 22 ABMR, 13 MVI and 16 normal cases. Glomeruli in ABMR and MVI had more T-cells and CD68+ infiltration than normal biopsies, although TIA1+ was only increased in MVI (P &lt; 0.001), suggesting increased T-cell cytotoxic capacity. Peritubular capillaries displayed more circulating T-cells, CD56+ TIA1+ and CD68+ in ABMR and MVI groups. Contrarily, MVI cases showed mild circulating plasma cell infiltration (CD138+) in peritubular capillaries (P = 0.059) and interstitial aggregates (P = 0.024) compared with ABMR (Figure 1).

CONCLUSION

In conclusion, MVI without HLA-DSA and C4d+ displays decreased circulating T-cell and NK cells, and intense T-cell and NK cell cytotoxic infiltration in the allograft, similar to ABMR. However, the deficiency of plasma cell infiltration in MVI suggests a different underlying stimulus from ABMR.

MO948: Impact of DE Novo Immunosuppression in The Covid-19 Serological Status at Kidney Transplantation

BACKGROUND AND AIMS

COVID-19 infection has heavily impacted our national health system since March-2020. Although the kidney transplant (KT) activity was strongly reduced initially, nowadays it is partially recovered by using ‘COVID-clean’ pathways and vaccination of KT candidates since February-2021. However, scarce information is available regarding how de novo KT immunosuppression influences the serological status of vaccinated recipients.

METHOD

We reviewed the course of 38 de novo KT recipients transplanted between March-September 2021 fully vaccinated before KT. SARS-CoV-2 IgG antibodies against Spike (IgG-S) before and after KT (median: 32 days) were quantified with a serological assay (positive ≥13.0 AU/mL).

RESULTS

Of 38 recipients, 35 showed positive IgG-S at KT (92%). We exclude from the analysis, 4 recipients with COVID infection which interfered the analysis and 5 with inappropriate samples. The remaining 26 recipients had received the second dose of the mRNA vaccine a median time of 48 days before the pre-KT IgG determination. All patients maintained IgG-S over the cut-off after KT, but we observed that half de novo recipients (53.8%) showed a 50% reduction in the level of IgG-S at 1 month: 12/20 (60%) of those who received induction with basiliximab and 2/6 (33%) who received thymoglobulin. Regarding the impact of maintenance immunosuppression under induction with basiliximab, the IgG-S levels halved in 50% of those with tacrolimus-mycophenolate and 67% with tacrolimus-everolimus.

The restricted analysis of IgG-S levels excluding five outliers before KT (>800 AU/mL) showed the most intense reduction in three KT recipients who received thymoglobulin-tacrolimus- mycophenolate (263.8 versus 68.8, 74%) compared with seven basiliximab-tacrolimus-mycophenolate cases (494.4 versus 359.8, 27%) and eleven basiliximab-tacrolimus-everolimus (344.0 versus 306.4, 11%) KT recipients.

CONCLUSION

Immunosuppression in de novo KT recipients reduces significantly the seroprotective levels of antibodies anti-Spike induced by COVID m-RNA vaccines in more than half the recipients. In our experience, the combination of thymoglobulin, tacrolimus and mycophenolate produces a more intense reduction than the combination of basiliximab with tacrolimus and mycophenolate or everolimus.

Outcomes of Frail Patients While Waiting for Kidney Transplantation: Differences between Physical Frailty Phenotype and FRAIL Scale

Frailty is associated with poorer outcomes among patients waiting for kidney transplantation (KT). Several different tools to measure frailty have been used; however, their predictive value is unknown. This is a prospective longitudinal study of 449 KT candidates evaluated for frailty by the Physical Frailty Phenotype (PFP) and the FRAIL scale. During the study period, 296 patients received a KT, while 153 remained listed. Patients who did not get receive a transplant were more frequently frail according to PFP (16.3 vs. 7.4%, p = 0.013). Robust patients had fewer hospital admissions during the 1st year after listing (20.8% if PFP = 0 vs. 43.4% if ≥1, and 27.1% if FRAIL = 0 vs. 48.9% if ≥1) and fewer cardiovascular events (than FRAIL ≥ 1) or major infectious events (than PFP ≥ 1). According to PFP, scoring 1 point had an impact on patient survival and chance of transplantation in the univariate analysis. The multivariable analysis corroborated the result, as candidates with PFP ≥ 3 had less likelihood of transplantation (HR 0.45 [0.26–0.77]). The FRAIL scale did not associate with any of these outcomes. In KT candidates, pre-frailty and frailty according to both the PFP and the FRAIL scale were associated with poorer results while listed. The PFP detected that frail patients were less likely to receive a KT, while the FRAIL scale did not.

Recurrence of IgA Nephropathy after Kidney Transplantation in Adults

BACKGROUND AND OBJECTIVES

In patients with kidney failure due to IgA nephropathy, IgA deposits can recur in a subsequent kidney transplant. The incidence, effect, and risk factors of IgA nephropathy recurrence is unclear, because most studies have been single center and sample sizes are relatively small.

DESIGN, SETTING, PARTICIPANTS, & MEASUREMENTS

We performed a multicenter, international, retrospective study to determine the incidence, risk factors, and treatment response of recurrent IgA nephropathy after kidney transplantation. Data were collected from all consecutive patients with biopsy-proven IgA nephropathy transplanted between 2005 and 2015, across 16 "The Post-Transplant Glomerular Disease" study centers in Europe, North America, and South America.

RESULTS

Out of 504 transplant recipients with IgA nephropathy, recurrent IgA deposits were identified by kidney biopsy in 82 patients; cumulative incidence of recurrence was 23% at 15 years (95% confidence interval, 14 to 34). Multivariable Cox regression revealed a higher risk for recurrence of IgA deposits in patients with a pre-emptive kidney transplant (hazard ratio, 3.45; 95% confidence interval, 1.31 to 9.17) and in patients with preformed donor-specific antibodies (hazard ratio, 2.59; 95% confidence interval, 1.09 to 6.19). After kidney transplantation, development of de novo donor-specific antibodies was associated with subsequent higher risk of recurrence of IgA nephropathy (hazard ratio, 6.65; 95% confidence interval, 3.33 to 13.27). Immunosuppressive regimen was not associated with recurrent IgA nephropathy in multivariable analysis, including steroid use. Graft loss was higher in patients with recurrence of IgA nephropathy compared with patients without (hazard ratio, 3.69; 95% confidence interval, 2.04 to 6.66), resulting in 32% (95% confidence interval, 50 to 82) graft loss at 8 years after diagnosis of recurrence.

CONCLUSIONS

In our international cohort, cumulative risk of IgA nephropathy recurrence increased after transplant and was associated with a 3.7-fold greater risk of graft loss.

Novel Dent disease 1 cellular models reveal biological processes underlying ClC-5 loss-of-function

Dent disease 1 (DD1) is a rare X-linked renal proximal tubulopathy characterized by low molecular weight proteinuria and variable degree of hypercalciuria, nephrocalcinosis and/or nephrolithiasis, progressing to chronic kidney disease. Although mutations in the electrogenic Cl-/H+ antiporter ClC-5, which impair endocytic uptake in proximal tubule cells, cause the disease, there is poor genotype-phenotype correlation and their contribution to proximal tubule dysfunction remains unclear. To further discover the mechanisms linking ClC-5 loss-of-function to proximal tubule dysfunction, we have generated novel DD1 cellular models depleted of ClC-5 and carrying ClC-5 mutants p.(Val523del), p.(Glu527Asp) and p.(Ile524Lys) using the human proximal tubule-derived RPTEC/TERT1 cell line. Our DD1 cellular models exhibit impaired albumin endocytosis, increased substrate adhesion and decreased collective migration, correlating with a less differentiated epithelial phenotype. Despite sharing functional features, these DD1 cell models exhibit different gene expression profiles, being p.(Val523del) ClC-5 the mutation showing the largest differences. Gene set enrichment analysis pointed to kidney development, anion homeostasis, organic acid transport, extracellular matrix organization and cell-migration biological processes as the most likely involved in DD1 pathophysiology. In conclusion, our results revealed the pathways linking ClC-5 mutations with tubular dysfunction and, importantly, provide new cellular models to further study DD1 pathophysiology.

Non-HLA Antibodies and Epitope Mismatches in Kidney Transplant Recipients With Histological Antibody-Mediated Rejection

Background

Correlation between antibody-mediated rejection (ABMR) and circulating HLA donor-specific antibodies (HLA-DSA) is strong but imperfect in kidney transplant (KT) recipients, raising the possibility of undetected HLA-DSA or non-HLA antibodies contributing to ABMR. Detailed evaluation of the degree of HLA matching together with the identification of non-HLA antibodies in KT may help to decipher the antibody involved.

Methods

We retrospectively assessed patients with transplant biopsies scored following Banff'15 classification. Pre- and post-transplant serum samples were checked for HLA and non-HLA antibodies [MICA-Ab, angiotensin-II type-1-receptor (AT1R)-Ab, endothelin-1 type-A-receptor (ETAR)-Ab and crossmatches with primary aortic endothelial cells (EC-XM)]. We also analyzed HLA epitope mismatches (HLA-EM) between donors and recipients to explore their role in ABMR histology (ABMRh) with and without HLA-DSA.

Results

One-hundred eighteen patients with normal histology (n = 19), ABMRh (n = 52) or IFTA (n = 47) were studied. ABMRh patients were HLA-DSApos (n = 38, 73%) or HLA-DSAneg (n = 14, 27%). Pre-transplant HLA-DSA and AT1R-Ab were more frequent in ABMRh compared with IFTA and normal histology cases (p = 0.006 and 0.003), without differences in other non-HLA antibodies. Only three ABMRhDSAneg cases showed non-HLA antibodies. ABMRhDSAneg and ABMRhDSApos cases showed similar biopsy changes and graft-survival. Both total class II and DRB1 HLA-EM were associated with ABMRhDSApos but not with ABMRhDSAneg. Multivariate analysis showed that pre-transplant HLA-DSA (OR: 3.69 [1.31-10.37], p = 0.013) and AT1R-Ab (OR: 5.47 [1.78-16.76], p = 0.003) were independent predictors of ABMRhDSApos.

Conclusions

In conclusion, pre-transplant AT1R-Ab is frequently found in ABMRhDSApos patients. However, AT1R-Ab, MICA-Ab, ETAR-Ab or EC-XM+ are rarely found among ABMRhDSAneg patients. Pre-transplant AT1R-Ab may act synergistically with preformed or de novo HLA-DSA to produce ABMRhDSApos but not ABMRhDSAneg. HLA epitope mismatch associates with ABMRhDSApos compared with ABMRhDSAneg, suggesting factors other than HLA are responsible for the damage.

MO206MALE SEX IS ASSOCIATED WITH IN-HOSPITAL DEATH IN NON-DIALYSIS CKD PATIENTS WITH COVID-19

Background and Aims

Coronavirus disease (COVID-19), caused by Severe Acute Respiratory Syndrome-Coronavirus 2 (SARS-CoV-2) can lead to significant organ injury. CKD has been associated with increased mortality in previous epidemics, and male sex has been correlated with worse outcomes during COVID-19 in the general population. Our aim was to describe the differential effect of sex as a risk factor for in-hospital mortality among non-dialysis CKD subjects.

Method

Multicenter, observational cohort study including 136 adult patients with CKD and 136 age- and sex-matched controls who required admission for COVID-19 in three academic hospitals in Spain. Viral infection was confirmed by real-time RT-qPCR and/or serologic testing in all cases. Disease severity on admission was classified according to the WHO—China Joint Mission Report on COVID-19. The presence of CKD was defined as sustained eGFR <60 and >15 ml/min/1.73m2 within the 6 months prior to COVID-19 hospitalization. Demographic and clinical data were gathered from medical records. Outcomes were recorded during the following 28 days after admission. We applied Cox proportional hazards models, adjusted for age, sex, hypertension, diabetes and severe or critical disease at presentation.

Results

Due to the matched design, no differences were found regarding age and sex between cohorts. CKD patients suffered more frequently from hypertension and diabetes and presented higher 28-day mortality after hospital admission due to COVID-19 compared with age- and sex-matched controls (40.4 vs. 24.3%; P=0.004). In adjusted Cox regression analysis among CKD patients, only age (HR: 1.087, 95% CI: 1.047-1.128) and male sex (HR: 1.883, 95% CI: 1.045-3.391) were independent predictors of 28-day mortality. Comparatively, among patients without CKD, only age acted as an independent predictor for 28-day mortality (HR: 1.082, 95% CI: 1.033-1.133). None of the variables included in adjusted regression was able to predict ICU admission in any of the cohorts.

Conclusion

Male sex is associated with increased mortality, but not with ICU admission, after hospitalization due to COVID-19 among non-dialysis CKD patients. That effect was not observed among hospitalized controls without CKD.

MO954DONOR TYPE INFLUENCE IN EARLY POST KIDNEY TRASPLANTATION HYPERTRANSAMINASEMIA

Background and Aims

The early increase in transaminases after kidney transplant (KT) is a frequent finding. It has been associated with the cross-talk produced between liver and kidney in ischemia-reperfusion situations. However, the influence of the donor type has not been evaluated. We analyze the incidence, relevance and possible correlations of postKT hypertransaminasemia.

Method

Retrospective study (2004-2018) to analyze the increase in serum AST/ALT during the first 3 months after KT in 119 KT recipients of deceased donors, either brain death (DBD n=59), controlled after cardiac death (cDCD n=21) or uncontrolled after cardiac death (uDCD n=39). All recipients received induction with thymoglobulin and maintenance immunosuppression with tacrolimus and mycophenolate.

Results

Recipients of uDCD group were younger, with a higher proportion of men and lower percentage of diabetics and retransplants. Delayed graft function duration was longer, although serum creatinine was similar at 3 months between groups. There were no differences between recipients in terms of past medical liver disease, postKT transfusion requirement or vasoactive drug use. There were also no differences in cumulative thymoglobulin dose, and uDCD recipients presented, as expected, lower levels of tacrolimus at one week postKT (Table).

From all KT recipients, 37.3/45.3% presented with an increase in AST/ALT at 72 hours postKT. Regarding donor type, the percentage of recipients who experienced 72 hours postKT hypertransaminasemia was higher (69.2/82.1% in uDCD group vs 22/29.3% in DBD and 21.1/21.1% in cDCD, p&lt;0.001). This liver function alteration resolved early, and one month after transplant, AST/ALT values in all groups returned to baseline (Figure).

The multivariate analysis showed that uDCD recipients had x10 higher risk of developing early post-KT hypertransaminasemia than the other groups (for AST, OR 10.85 [2.463-47.826] and for ALT OR 11.15 [2.627-47.294]). However, when we tried to correlate this hypertransaminasemia with a prolonged delayed graft function (creatinine decrease&gt; 14 days postKT) we did not find any association.

Conclusion

Early postKT hypertransaminasemia is a frequent and transient event that is related to the kidney donor type, being more frequent in recipients of donors in uncontrolled cardiac death.

MO985EFFICACY AND SAFETY OF FERRIC CARBOXYMALTOSE IN THE MANAGEMENT OF EARLY POST-RENAL TRANSPLANT ANEMIA

Background and Aims

The efficacy and safety of intravenous ferric carboxymaltose (FeCarb) has been demonstrated both in patients with chronic kidney disease and dialysis, but its effects have not been evaluated in kidney transplant (KT) recipients.

Method

Retrospective study (2016-2018) of KT recipients who received FeCarb during the first 30 days after kidney transplantation (KT). Early efficacy was analyzed by evaluating the first determination of ferrokinetics and hemoglobin levels after administration and late efficacy with the determination &gt;90 days post-administration. Safety parameters were also analyzed.

Results

Out of 283 KT performed, 77 recipients received one dose of FeCarb (52 received a 500mg dose and 25 a 1000mg dose) after a median of 6 days after the KT (IQR 3.5-9 days). 24 patients required transfusion after administration, 7 of them in the setting of concomitant event and 17 for non-response to FeCarb. Among the non-responders (n=17) there was a higher percentage of women, the initial hemoglobin was lower and they received a higher dose of FeCarb (Table). Responders (n=53) improved early and late ferrokinetic and anemia parameters (Figure). In the multivariate analysis adjusted by gender, controlled infection at the time of FeCarb administration, dose of FeCarb administered, immunosuppression, and previous treatment with erythropoietin, hemoglobin levels below 8 g/dL were associated with increased risk of transfusion after FeCarb administration (HR 11.30 [3.03-42.2]). Tolerability was excellent, with no immediate adverse reactions after FeCarb administration. 17 responders had a controlled infection at the time of FeCarb administration (median days under antibiotic treatment: 3, IQR 1-5). The infection did not worsen the response to FeCarb and no clinical impairment after FeCarb administration was observed.

Conclusion: FeCarb administration in early post-transplant anemia is effective in patients with hemoglobin higher than 8g/dl and is not associated with increased risk of infection deterioration.

MO381RISK FACTORS FOR AKI DURING COVID-19 AMONG NON-DIALYSIS CKD PATIENTS

Background and Aims

AKI is a strong risk factor for adverse outcomes during Coronavirus disease (COVID-19) in the general population. CKD has been correlated with increased risk of AKI both in the outpatient and inpatient settings. We aimed to define potential risk factors for AKI among patients with non-dialysis CKD admitted due to COVID-19.

Method

Multicenter, observational cohort study including 136 adult patients with CKDand 136 age- and sex-matched controls who required admission for COVID-19 in three academic hospitals. Viral infection was confirmed by real-time RT-qPCR and/or serologic testing in all cases. Disease severity on admission was classified according to the WHO—China Joint Mission Report on COVID-19; briefly subjects with COVID-19 were divided into mild (laboratory confirmed, without pneumonia), moderate (laboratory confirmed with pneumonia), severe (dyspnea and/or lung infiltrates >50% of the lung field within 24–48 h) and critical (respiratory failure requiring mechanical ventilation, shock, or other organ failure that requires intensive care). AKI was defined using the 2012 KDIGO classification. CKD was defined as sustained eGFR <60 and >15 ml/min/1.73m2 within the 6 months prior to COVID-19 hospitalization. Baseline eGFR was calculated using the CKD-EPI equation. Demographic and clinical data were gathered from medical records. Outcomes were recorded during the following 28 days after admission. We applied logistic regression analysis to describe potential predictors for AKI.

Results

Median age was 80 years (IQR: 70-86). 58.8% of patients were males. The most common symptom on admission was fever (68.8%), followed by cough (57.7%). The majority of subjects presented with severe COVID-19 on admission (75.7%). During 28-day follow-up, 87 patients (32%) developed Stage 1 AKI, 17 subjects (6.3%) developed Stage 2 AKI and 12 patients (4.4%) developed Stage 3 AKI.

AKI was more frequent (61 vs 24.3%) and more severe (Stage 2 AKI: 10.3 vs 2.2%; Stage 3 AKI: 6.6 vs 2.2%) among CKD patients. In adjusted logistic regression analysis, only disease severity and baseline eGFR were independent predictors for AKI in COVID-19 patients that required hospitalization.

Conclusion

CKD patients suffer AKI more frequently and of higher severity during COVID-19. Baseline eGFR, along with COVID-19 severity, are strong predictor factors of AKI in this setting.

FC 129CHANGES IN PERIPHERAL NK CELLS IN KIDNEY TRANSPLANT RECIPIENTS WITH AND WITHOUT HLA DSA

Background and Aims

Antibody-mediated rejection (ABMR) is a frequent cause of renal allograft loss. There is increasing evidence of the role of Natural Killer (NK) cells in the establishment of ABMR damage. Our group described that patients with donor-specific antibodies (DSA) and ABMR present higher proportions of NKG2A+ NK cell subset in peripheral blood than those without HLA DSA or HLA antibodies.

Method

We selected 177 kidney transplant recipients (KT) with renal biopsies 2011-2017: 77 with ABMR (DSA+: 53, DSA-: 24) and 100 without ABMR (DSA+: 15, DSA-: 85). We assessed graft survival with a median time of follow-up since the renal biopsy of 53 months. In 138 KT we evaluated the peripheral blood NK cell immunophenotyping and its value as a prognostic biomarker.

Results

Graft survival was worse in ABMR-KT at the end of follow-up (p&lt;0.001) independently of DSA detection (p=0.63). Regarding NK cell immunophenotyping, we observed a lower proportion and absolute NK cell count in ABMR+DSA+-KT and ABMR+DSA--KT compared with ABMR-DSA--KT (p=0.027, p=0.017). ABMR+DSA+-KT showed higher proportion of NKG2A+ NK cells compared with ABMR-DSA--KT (p=0.007). All ABMR+ patients, independently of DSA detection, presented lower absolute NKG2A- NK cell count in comparison with ABMR-DSA--KT (p=0.001, p=0.017). Finally, a proportion of NKG2A- &lt;30% was associated with lower graft survival 36 months after graft biopsy with ABMR (p=0.067) (Figure).

Conclusion

Graft survival is worse in ABMR+ compared with ABMR- KT independently of DSA detection. Kidney transplant recipients with ABMR show reduced peripheral absolute numbers of NK cells and NKG2A- NK cells regardless of undetectable DSA. This NK cell phenotype associated with a worse medium-term graft survival in cases with ABMR.

Heterogeneity is a common ground in familial hypomagnesemia with hypercalciuria and nephrocalcinosis caused by CLDN19 gene mutations

BACKGROUND

Familial hypomagnesemia with hypercalciuria and nephrocalcinosis (FHHNC) is a rare tubulopathy caused by mutations in the CLDN16 or CLDN19 genes. Patients usually develop hypomagnesemia, hypercalciuria, nephrocalcinosis and renal failure early in life. Patients with CLDN19 mutations may also have ocular abnormalities. Despite clinical variability, factors associated with kidney function impairment, especially in patients with CLDN19 mutations, have not been addressed.

METHODS

Retrospective multicenter study of 30 genetically confirmed FHHNC Spanish patients. We analyzed kidney function impairment considering as outcomes chronic kidney disease (CKD) stage 3 and annual estimated glomerular filtration rate (eGFR) decline, to identify factors associated with the different phenotypes.

RESULTS

Of thirty patients, 27 had mutations in the CLDN19 gene (20 homozygous for the p.G20D mutation) and 3 in the CLDN16. Age at diagnosis was 1.71 (0.67-6.04) years and follow-up time was 8.34 ± 4.30 years. No differences in CKD stage 3-free survival based on CLDN19 mutation (p.G20D homozygous vs. other mutations) or gender were found, although females seemed to progress faster than males. Patients with more pronounced eGFR decline had higher PTH levels at diagnosis than those with stable kidney function, despite similar initial eGFR. Approximately 60% of CLDN19 patients presented ocular abnormalities. Furthermore, we confirmed high phenotypic intrafamilial variability.

CONCLUSIONS

In a contemporary cohort of FHHNC patients with CLDN19 mutations, females seemed to progress to CKD-stage 3 faster than males. Increased PTH levels at baseline may indicate a more severe renal course. There was high phenotype variability among patients with CLDN19 mutations and kidney function impairment  differed even between siblings.

Outcomes of COVID-19 Among Hospitalized Patients With Non-dialysis CKD

Background: Coronavirus disease 2019 (COVID-19), caused by Severe Acute Respiratory Syndrome-Corona Virus 2 has generated significant impact on global health worldwide. COVID-19 can cause pneumonia and organ injury. Chronic kidney disease (CKD) has been associated with increased mortality in previous epidemics, but there is a paucity of data regarding actual risks for non-dialysis CKD patients with COVID-19.

Methods: Multicenter, observational cohort study including 136 non-dialysis CKD patients and 136 age- and sex-matched controls that required hospitalization due to COVID-19. Patients with end-stage renal disease, a kidney transplant or without registered baseline glomerular filtration rate prior to COVID-19 infection were excluded. CKD and acute kidney injury (AKI) were defined according to KDIGO criteria.

Results: CKD patients had higher white blood cell count and D-dimer and lower lymphocyte percentage. No differences were found regarding symptoms on admission. CKD was associated with higher rate of AKI (61 vs. 24.3%) and mortality (40.4 vs. 24.3%). Patients with AKI had the highest hazard for death (AKI/non-CKD HR:7.04, 95% CI:2.87–17.29; AKI/CKD HR:5.25, 95% CI: 2.29–12.02), followed by CKD subjects without AKI (HR:3.39, 95% CI:1.36–8.46). CKD status did not condition ICU admission or length of in-hospital stay.

Conclusions: CKD patients that require hospitalization due to COVID-19 are exposed to higher risk of death and AKI.

Validation of a survival benefit estimator tool in a cohort of European kidney transplant recipients

Pre-transplant prognostic scores help to optimize donor/recipient allocation and to minimize organ discard rates. Since most of these scores come from the US, direct application in non-US populations is not advisable. The Survival Benefit Estimator (SBE), built upon the Estimated Post-Transplant Survival (EPTS) and the Kidney Donor Profile Index (KDPI), has not been externally validated. We aimed to examine SBE in a cohort of Spanish kidney transplant recipients. We designed a retrospective cohort-based study of deceased-donor kidney transplants carried out in two different Spanish hospitals. Unadjusted and adjusted Cox models were applied for patient survival. Predictive models were compared using Harrell’s C statistics. SBE, EPTS and KDPI were independently associated with patient survival (p ≤ 0.01 in all models). Model discrimination measured with Harrell’s C statistics ranged from 0.57 (KDPI) to 0.69 (SBE) and 0.71 (EPTS). After adjustment, SBE presented similar calibration and discrimination power to that of EPTS. SBE tended to underestimate actual survival, mainly among high EPTS recipients/high KDPI donors. SBE performed acceptably well at discriminating post-transplant survival in a cohort of Spanish deceased-donor kidney transplant recipients, although its use as the main allocation guide, especially for high KDPI donors or high EPTS recipients requires further testing.

Activation of final complement components after kidney transplantation as a marker of delayed graft function severity

Background

Ischaemia-reperfusion (I/R) damage is a relevant cause of delayed graft function (DGF). Complement activation is involved in experimental I/R injury, but few data are available from kidney transplant (KT) patients. We studied the dynamics of membrane attack complex (C5b-9) as a soluble fraction (SC5b-9) and the histological deposit pattern of C3b, complement Factor H (FH) and C5b-9 in DGF patients.

Methods

We evaluated SC5b-9 levels in 59 recipients: 38 with immediate graft function and 21 with DGF. The SC5b-9 was measured at admission for KT and 7 days after KT. DGF-kidney biopsies (n = 12) and a control group of 1-year protocol biopsies without tissue damage (n = 4) were stained for C5b-9, C3b and FH.

Results

SC5b-9 increased significantly in DGF patients (Day 0: 6621 ± 2202 mAU/L versus Day 7: 9626 ± 4142  mAU/L; P = 0.006), while it remained stable in non-DGF patients. Days 0-7 increase >5% was the better cut-off associated with DGF versus non-DGF patient discrimination (sensitivity = 81%). In addition, SC5b-9 increase was related to DGF duration and worse graft function, and independently associated with DGF occurrence. SC5b-9, C3b and FH stains were observed in tubular epithelial cells basal membrane. DGF-kidney biopsies showed a more frequently high-intensity stain, a higher number of tubules with positive stain and larger perimeter of tubules with positive stains for SC5b-9, C3b and FH than control patients.

Conclusions

Both SC5b-9 levels and SC5b-9, C3b and FH deposits in tubular epithelial cells basal membrane are highly expressed in patients experiencing DGF. SC5b-9 levels increase could be useful as a marker of DGF severity.

COVID-19 in elderly kidney transplant recipients

The SARS-Cov-2 infection disease (COVID-19) pandemic has posed at risk the kidney transplant (KT) population, particularly the elderly recipients. From March 12 until April 4, 2020, we diagnosed COVID-19 in 16 of our 324 KT patients aged ≥65 years old (4.9%). Many of them had had contact with healthcare facilities in the month prior to infection. Median time of symptom onset to admission was 7 days. All presented with fever and all but one with pneumonia. Up to 33% showed renal graft dysfunction. At infection diagnosis, mTOR inhibitors or mycophenolate were withdrawn. Tacrolimus was withdrawn in 70%. The main treatment combination was hydroxychloroquine and azithromycin. A subset of patients was treated with anti-retroviral and tocilizumab. Short-term fatality rate was 50% at a median time since admission of 3 days. Those who died were more frequently obese, frail, and had underlying heart disease. Although a higher respiratory rate was observed at admission in nonsurvivors, symptoms at presentation were similar between both groups. Patients who died were more anemic, lymphopenic, and showed higher D-dimer, C-reactive protein, and IL-6 at their first tests. COVID-19 is frequent among the elderly KT population and associates a very early and high mortality rate.

Kidney transplantation outcomes from elderly donors after circulatory death: a comparison with elderly brain-dead donors

Background

The use of kidneys from elderly controlled donation after circulatory death (cDCD) donors has increased significantly in recent years. Concerns about outcomes achieved with these elderly cDCD kidneys have arisen. We aimed to compare outcomes from elderly cDCD kidney transplant recipients (KTrs) and elderly donation after brain death donors (DBDs) in KTrs.

Methods

We conducted a single-centre retrospective study including 87 cDCD-KTrs (46 from donors ≥65 years of age and 41 from <65 years) and 126 DBD-KTrs from donors ≥65 years of age from 2013 through 2017). Young cDCD-KTrs were used as controls. The median follow-up was 27.1 months for all cDCD-KTrs and 29.7 months for DBD-KTrs ≥65 years of age.

Results

Donors >65 years of age represented more than half of our global cDCD cohort (52.9%). KTs from elderly cDCDs had similar rates of delayed graft function, primary non-function and vascular complications compared with young cDCD-KTrs and elderly DBD-KTrs. Short and medium-term graft survival from elderly cDCD kidneys are excellent and are comparable to those from young cDCD and elderly DBD kidneys (90% young cDCD versus 88% elderly cDCD versus 80% elderly DBD at 36 months, P = 0.962 and 0.180, respectively). Although recipients from cDCDs ≥65 years of age showed lower 3-year patient survival (78% versus 87% in elderly DBD-KTrs; P = 0.01), recipient age was the only determinant of patient survival [hazard ratio 1.10 (95% confidence interval 1.02–1.17); P < 0.01], without any influence of donor characteristics.

Conclusions

The use of kidneys from elderly cDCDs is increasing in Spain. Short- and medium-term graft outcomes are similar when comparing kidneys from elderly cDCDs and DBDs. Recipient age is the only determinant of patient survival. Additional studies are needed to assess long-term outcomes.

Relevance of KDPI value and acute rejection on kidney transplant outcomes in recipients with delayed graft function - a retrospective study

Delayed graft function (DGF) is associated with poorer graft survival and higher rate of acute rejection (AR). It is unknown whether this negative influence relies on the increased risk of AR or the DGF itself. The different Kidney Donor Profile Index (KDPI) values may also play a role in this interaction. Retrospective study aimed to evaluate the impact of DGF on graft function and graft survival in a subset of KT recipients (2004-2017). We also analyzed the relationship between KDPI and DGF. The study includes 601 KT, 226 of them (37%) developed DGF. Graft survival was lower in patients with DGF compared with non-DGF patients. Multivariable analysis revealed DGF as risk factor for graft loss, independently of the presence or not of acute rejection. Between DGF patients, we observed poorer graft survival in patients with higher KDPI value (>85%). We observed a trend of a greater impact of KDPI in patients with DGF, although this interaction was not statistically significant. Additionally, we observed poorer 12-month graft function in DGF patients. DGF is related to poorer graft survival independently of the developed acute rejection. This negative impact might be influenced by high KDPI values.

P1601COMPLEMENT MEMBRANE ATTACK COMPLEX DURING THE FIRST WEEK AFTER KIDNEY TRANSPLANTATION AS SEVERITY BIOMARKER TO DELAYED GRAFT FUNCTION

Background and Aims

Ischemia-reperfusion (I/R) damage is a relevant cause of delayed graft function (DGF). Complement activation is involved in experimental I/R injury, but few data are available about the expression of the complement cascade final component -membrane attack complex (MAC)- and I/R injury in KT patients. We studied the dynamics of membrane attack complex (MAC) as plasma fraction (pMAC) and the histological deposit pattern of C3b, complement factor H (FH) and MAC in DGF patients.

Method

We evaluated pMAC levels in 59 recipients, 38 with immediate graft function and 21 without serum creatinine decreased at day 7 (DGF). pMAC was measured at admission for KT (day 0) and 7 days after KT (day 7). Sandwich ELISAs were used to measure MAC. Additionally, we performed imunohistoquimical stained for MAC, C3b and kidney biopsies (KB) with DGF (n=12) and a control group of one-year protocol biopsies without damage (n=4)

Results

Patients in the DGF group were older, more frequently diabetics and received kidneys from older donors and more frequently controlled cardio-circulatory death type.

Day0 and day7 post-KT pMAC levels were similar in non-DGF patients 5902±3049 mAu/L vs 6178±2882 mAu/L; p=0.686). However, patients with DGF showed a significant increase of pMAC levels between day0 and day7 (6621±2202 mAu/L vs 9625±4142 mAu/L; p=0.006. Figure 1

Percentage pMAC levels increase (Δ0-7 pMAC%) discriminative assessment analyzed by ROC curve showed a good discriminative value for DGF with an AUC of 0.78; p&lt;0.001 (sensitivity 81%, specificity 66% by cut-off point of 5%). In patients with DGF longer than ten days, we found more frequently patients with a Δ0-7 pMAC &gt;5% (83% vs 17% Δ0-7 pMAC &lt;5% ; p=0.003).Patients with DGF showed renal function at 3 and 6 months, but worse renal function 1 year after KT (serum creatinine 1.78±0.61 vs 1.35±0.30 mg/dl in non-DGF patients). DGF patients with Δ0-7 pMAC &gt;5% displayed worse renal function 1 and 2 year after KT compared to DGF patients with Δ0-7 pMAC &lt;5%.

MAC, C3b and FH stains were observed in tubular epithelial cells basal membrane. DGF-kidney biopsies showed more frequently high-intensity stain for MAC and FH than controls, without differences to C3b stain. DGF-kidney biopsies also showed a higher number of tubules with positive stain and larger perimeter of tubules with positive stains for MAC, C3b and FH than the controls. Figure 2.

Among the 12 patients with DGF-biopsies, three (25%) never recovered renal function, all of them presented Δ0-7 pMAC &gt;5% and intense, diffuse and positive staining in more than 50% of tubular perimeter for MAC, FH and C3b

Conclusion

Complement activation during peritrasplant period could be related with the severity of graft injury and the presence of DGF. Therefore, the determination of MAC levels could be useful to identify patients with possible complement dependent graft injury that might benefit from complement inhibitor therapies

Usefulness of the KDPI in Spain: A comparison with donor age and definition of standard/expanded criteria donor

INTRODUCTION

Kidney donor shortage requires expanding donor selection criteria, as well as use of objective tools to minimize the percentage of discarded organs. Some donor pre-transplant variables such as age, standard/expanded criteria donor (SCD/ECD) definition and calculation of the Kidney Donor Profile Index (KDPI), have demonstrated correlations with patient and graft outcomes. We aimed to establish the accuracy of the three models to determine the prognostic value of kidney transplantation (KT) major outcomes.

MATERIAL AND METHODS

We performed a retrospective study in deceased donor KTs at our institution. Unadjusted Cox and Kaplan-Meier survival, and multivariate Cox analyses were fitted to analyze the impact of donor age, SCD/ECD and KDPI on outcomes.

RESULTS

389 KTs were included. Mean donor age was 53.6±15.2 years; 163 (41.9%) came from ECD; mean KDPI was 69.4±23.4%. Median follow-up was 51.9 months. The unadjusted Cox and Kaplan-Meier showed that the three prognostic variables of interest were related to increased risk of patient death, graft failure and death-censored graft failure. However, in the multivariate analysis only KDPI was related to a higher risk of graft failure (HR 1.03 [95% CI 1.01-1.05]; p=0.014).

CONCLUSIONS

SCD/ECD classification did not provide significant prognostic information about patient and graft outcomes. KDPI was linearly related to a higher risk of graft failure, providing a better assessment. More studies are needed before using KDPI as a tool to discard or accept kidneys for transplantation.

Impact of Recurrent Acute Kidney Injury on Patient Outcomes

BACKGROUND/AIMS

Recurrent acute kidney injury (AKI) is common among patients after a first hospitalized AKI. However, little is known about the prognosis of recurrent AKI episodes in chronic kidney disease (CKD) development, cardiovascular events and mortality.

METHODS

A retrospective study included patients admitted to our Hospital from 2000 to 2010. AKI was defined according to the Acute Dialysis Quality Initiative criteria. In the follow-up period after the first AKI episode, clinical, laboratory data and the number of repeated AKI episodes, etiology and severity were recorded.

RESULTS

Among the 359 AKI survivor patients included, 250 new AKI episodes were observed in 122 patients (34%). Variables independently associated to new episodes were: type 2 DM [OR 1.2, 95%CI 1.2-3.8, p=0.001], ischemic heart disease [OR 1.9; 95%CI 1.1-3.6, p=0.012], and SCr at the first AKI event>2,6 mg/dl [OR 1.2; 95%CI 1.03-1.42, p=0.02]. Development of CKD during four years follow-up was more frequent in patients with recurrent AKI, HR [2.2 (95% CI: 1.09-4.3, p=0.003)] and 44% of recurrent AKI patients who developed CKD occurred during the first 6 months after the initial event. Cardiovascular events were more frequent among patients with recurrent AKI patients than in those with one AKI episode (47.2% vs 24%, p=0.001). Mortality at 4 years was higher in the patient subgroup with several episodes of AKI as compared with those with a single episode [HR: 4.5 (95% CI 2.7-7.5) p<0.001].

CONCLUSION

Episodes of recurrent AKI have a high potential to be associated with relevant complications such as cardiovascular events, mortality and CKD development.

MDRD or CKD-EPI for glomerular filtration rate estimation in living kidney donors

INTRODUCTION

The evaluation of the measured Glomerular Filtration Rate (mGFR) or estimated Glomerular Filtration Rate (eGFR) is key in the proper assessment of the renal function of potential kidney donors. We aim to study the correlation between glomerular filtration rate estimation equations and the measured methods for determining renal function.

MATERIAL AND METHODS

We analysed the relationship between baseline GFR values measured by Tc-⁹⁹m-DTPA (diethylene-triamine-pentaacetate) and those estimated by the four-variable Modification of Diet in Renal Disease (MDRD4) and Chronic Kidney Disease Epidemiology Collaboration (CKD-EPI) equations in a series of living donors at our institution.

RESULTS

We included 64 donors (70.6% females; mean age 48.3±11 years). Baseline creatinine was 0.8±0.1 mg/dl and it was 1.1±0.2 mg/dl one year after donation. The equations underestimated GFR when measured by Tc⁹⁹m-DTPA (MDRD4-9.4 ± 25ml/min, P<.05, and CKD-EPI-4.4 ± 21ml/min). The correlation between estimation equations and the measured method was superior for CKD-EPI (r=.41; P<.004) than for MDRD4 (r=.27; P<.05). eGFR decreased to 59.6±11 (MDRD4) and 66.2±14ml/min (CKD-EPI) one year after donation. This means a mean eGFR reduction of 28.2±16.7 ml/min (MDRD4) and 27.31±14.4 ml/min (CKD-EPI) at one year.

CONCLUSIONS

In our experience, CKD-EPI is the equation that better correlates with mGFR-Tc⁹⁹m-DTPA when assessing renal function for donor screening purposes.

Renal graft survival according to Banff 2013 classification in indication biopsies

INTRODUCTION

The impact of acute rejection in kidney graft survival is well known, but the prognosis of other diagnoses is uncertain. We evaluated the frequency and impact on graft survival of different diagnostic categories according to the Banff 2013 classification in a cohort of renal transplant recipients.

MATERIAL AND METHODS

Retrospective study of 495 renal biopsies by indication in 322 patients from 1990-2014. Two independent observers reviewed the histological reports, reclassifying according to the Banff 2013 classification.

RESULTS

Of 495 biopsies, 28 (5.7%) were not diagnostic. Of the remaining 467, 10.3% were «normal» (category 1), 19.6% antibody-mediated changes (category 2), 5.9% «borderline» changes (category 3), 8.7% T-cell-mediated rejection (category 4), 23.4% interstitial fibrosis/tubular atrophy (IFTA) (category 5) and 26.5% with other diagnoses (category 6). As time after transplantation increases, diagnoses of categories 1, 3 and 4 decrease, while categories 5 and 2 increase. Worse graft survival with category 2 diagnosis was observed (45% at 7.5 years, HR 4.29 graft loss [95% CI, 2.39-7.73]; P≤.001, compared to category 1). Grafts with «unfavourable histology» (chronic antibody-mediated rejection, moderate-severe IFTA) presented worse survival that grafts with «favourable histology» (normal, acute tubular necrosis, mild IFTA).

CONCLUSIONS

The Banff 2013 classification facilitates a histological diagnosis in 95% of indication biopsies. While diagnostic category 6 is the most common, a change in the predominant histopathology was observed according to time elapsed since transplantation. Antibody-mediated changes are associated with worse graft survival.