Renal graft survival according to Banff 2013 classification in indication biopsies

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.

Supervivencia del injerto y pacientes postrasplante renal de un hospital de Yucatán, México

Introducción: El trasplante de órganos es considerado como uno de los mayores avances de la medicina, no solo por recuperar la salud, sino por mejorar la calidad de vida de las personas con enfermedades crónicas o terminales.Objetivo: Identificar la supervivencia del injerto y pacientes sometidos a trasplante renal, así como los factores asociados en un Hospital de Alta Especialidad de Mérida, Yucatán, México.Material y Método: Estudio epidemiológico, observacional, longitudinal y retrospectivo donde se analizó el 100% de los expedientes disponibles de pacientes con trasplante renal, cuyo procedimiento se realizó a partir de enero de 2010 a diciembre de 2018.Resultados: La supervivencia global de los pacientes, fue de 96,7% a 1 año (IC:95%: 0,92-0,99) y 90,7% a 5 años (IC:95%: 0,75-0,97). La administración de terapia inmunosupresora previa al trasplante es un factor independiente de protección frente al desenlace de mortalidad o fallo del injerto (p=0,02). La supervivencia del injerto fue de 79,2% a 1 año (IC:95%: 0,71-0,85), y 41,37% a 5 años (IC:95%: 0,27-0,54). La dislipidemia (p=0,01), la Diabetes Tipo 2 (p=0,09), la isquemia fría (p=0,01), la isquemia caliente (p=0,02), la edad (p=0,03), y el Índice de Masa Corporal (p=0,01) fueron determinantes de la supervivencia del injerto.Conclusiones: La supervivencia del paciente y del injerto son distintas. La administración de inmunosupresor previo al trasplante afecta la supervivencia del paciente; mientras que factores de riesgo cardiovascular y los tiempos de isquemia estuvieron ligados a la supervivencia del injerto.

Histological diagnosis from kidney transplant biopsy can contribute to prediction of graft survival

Aim

The primary aim of this study was to in depth examine if the histological findings in a transplanted kidney biopsy can predict the prognosis for the graft and the patient. The secondary aim was to extend knowledge of the impact of time elapsed on biopsy findings.

Methods

Data from 1462 patients were merged from a kidney transplantation registry and a biopsy registry during 1 January 2007 and 30 September 2017. Kaplan–Meier analysis and multivariate Cox‐regression analysis were performed and hazard ratios (HR) with 95% confidence intervals (CI) were presented.

Results

Compared to normal biopsy findings, graft survival after biopsy (gsaBiopsy) was shorter for patients with glomerular diseases (HR 8.2, CI:3.2–21.1), rejections (HR 4.2, CI:1.7–10.3), chronic changes including IFTA (HR 3.2, CI:1.3–8.0), acute tubular injuries (HR 3.0, CI:1.2–7.8), and borderline changes (HR 2.9, CI:1.1–7.6). Sub‐analysis of rejections showed shorter gsaBiopsy for chronic TCMR (HR 4.7, CI:1.9–11.3), active ABMR (HR 3.6, CI:1.7–7.7) and chronic ABMR (HR 3.5, CI:2.0–6.0). Patients with TCMR Banff grade II (HR 0.35, CI:0.20–0.63) and grade I (HR 0.52, CI:0.29–0.93) had a better gsaBiopsy compared to all other types of rejections.

Conclusion

Shorter gsaBiopsy was noted in kidneys with glomerular diseases, rejections, acute tubular injuries and borderline changes. TCMR Banff rejections grade I and II were associated with a better prognosis.

This Swedish single centre study showed that the impact on allograft survival is dependent on the nature of the biopsy findings, with histological findings of glomerular disease, severe rejections and chronic changes being associated with more rapid allograft loss.

Long-Term Redistribution of Peripheral Lymphocyte Subpopulations after Switching from Calcineurin to mTOR Inhibitors in Kidney Transplant Recipients

Classical immunosuppression based on steroids, calcineurin inhibitors, and mycophenolate results in several unwanted effects and unsatisfactory long-term outcomes in kidney transplantation (KT). New immunosuppressors search for fewer adverse events and increased graft survival but may have a distinct impact on graft function and immunological biomarkers according to their mechanism of action. This prospective study evaluates the immunological effect of tacrolimus to serine/threonine protein kinase mechanistic target of rapamycin inhibitors (mTORi) conversion in 29 KT recipients compared with 16 controls maintained on tacrolimus. We evaluated renal function, human leukocyte antigen (HLA) antibodies and peripheral blood lymphocyte subsets at inclusion and at 3, 12, and 24 months later. Twenty immunophenotyped healthy subjects served as reference. Renal function remained stable in both groups with no significant change in proteinuria. Two patients in the mTORi group developed HLA donor-specific antibodies and none in the control group (7% vs. 0%, p = 0.53). Both groups showed a progressive increase in regulatory T cells, more prominent in patients converted to mTORi within the first 18 months post-KT (p < 0.001). All patients showed a decrease in naïve B cells (p < 0.001), excepting those converted to mTORi without receiving steroids (p = 0.31). Transitional B cells significantly decreased in mTORi patients (p < 0.001), independently of concomitant steroid treatment. Finally, CD56^bright and CD94/NK group 2 member A receptor positive (NKG2A⁺) Natural Killer (NK) cell subsets increased in mTORi- compared to tacrolimus-treated patients (both p < 0.001). Patients switched to mTORi displayed a significant redistribution of peripheral blood lymphocyte subpopulations proposed to be associated with graft outcomes. The administration of steroids modified some of these changes.

Peripheral blood lymphocyte subsets change after steroid withdrawal in renal allograft recipients: a prospective study

Several studies have assessed clinical outcomes after steroid withdrawal (SW) in kidney transplant (KT) recipients, but little is known about its potential impact on lymphocyte subpopulations. We designed a prospective study to evaluate the long-term impact of SW in 19 KT recipients compared to 16 KT recipients without changes in immunosuppression (steroid maintenance, SM). We assessed renal function, presence of HLA antibodies and peripheral blood lymphocyte subsets at time of inclusion, and 3, 12 and 24 months later. The immunophenotype of 20 healthy subjects was also analyzed. Serum creatinine and proteinuria remained stable in SW and SM patients. SW did not associate with generation of de novo donor-specific antibodies. SW patients showed decreases in T-lymphocytes (p < 0.001), and in the CD4+ T cell subpopulation (p = 0.046). The proportion of B-lymphocytes (p = 0.017), and both naïve and transitional B cells increased compared to SM patients (p < 0.001). Changes in B cell subsets were detected 3 months after SW and persisted for 24 months. No changes were observed in NK cells related to steroid withdrawal. SW patients displayed significant changes in peripheral T and B cell subsets, transitioning to the phenotype detected in healthy subjects. This may be considered as a maintained positive effect of SW previously unnoticed.

Vectisol Formulation Enhances Solubility of Resveratrol and Brings Its Benefits to Kidney Transplantation in a Preclinical Porcine Model

Current organ shortages have led centers to extend the acceptance criteria for organs, increasing the risk for adverse outcomes. Current preservation protocols have not been adapted so as to efficiently protect these organs. Herein, we target oxidative stress, the key mechanism of ischemia reperfusion injury. Vectisol^® is a novel antioxidant strategy based on the encapsulation of resveratrol into a cyclodextrin, increasing its bioavailability. We tested this compound as an additive to the most popular static preservation solutions and machine perfusion (LifePort) in a preclinical pig model of kidney autotransplantation. In regard to static preservation, supplementation improved glomerular filtration and proximal tubular function early recovery. Extended follow-up confirmed the higher level of protection, slowing chronic loss of function (creatininemia and proteinuria) and the onset of histological lesions. Regarding machine perfusion, the use of Vectisol^® decreased oxidative stress and apoptosis at the onset of reperfusion (30 min post declamping). Improved quality was confirmed with decreased early levels of circulating SOD (Superoxide Dismutase) and ASAT (asparagine amino transferase). Supplementation slowed the onset of chronic loss of function, as well as interstitial fibrosis and tubular atrophy. The simple addition of Vectisol^® to the preservation solution significantly improved the performance of organ preservation, with long-term effects on the outcome. This strategy is thus a key player for future multi-drug therapy aimed at ischemia reperfusion in transplantation.