Citations

Abstract Introduction: Surveillance biopsies after kidney transplantation provide an opportunity to assess early renal disease processes, including diabetic nephropathy, before clinical manifestation. This study aimed to identify proteomic alterations in renal allografts at 5 years post-transplant (5yrPT) and their associations with histologic features in diabetic/obese (DM/OB) versus non-diabetic/non-obese (nDM/nOB) recipients. Methods: We studied protocol biopsies from 17 DM/OB and 14 nDM/nOB kidney transplant recipients at Mayo Clinic (2000–2012). Laser capture microdissection followed by mass spectrometry was used for proteomic profiling. Histologic assessment included Banff and Tervaert scoring and morphometric analysis. Statistical comparisons were performed using ANOVA with Tukey post-hoc testing. Results: DM/OB recipients demonstrated greater histologic and metabolic injury at 5yrPT. Proteomic analysis identified 101 glomerular and 86 non-glomerular proteins differentially expressed between groups. Significant alterations were observed in proteins associated with mitochondrial dysfunction, including VDAC1 (fold change [FC] 2.6, p = 0.03), NDUFB9 (FC 0.15, p = 0.009), and NDUFA9 (FC 1.72, p = 0.01). Extracellular matrix remodeling proteins COL6A1, COL6A2, and COL6A3 were upregulated (FC 1.6–1.8, p < 0.05). Immune and inflammatory markers C9 (FC 1.6, p < 0.03) and TGFBI (FC 1.7, p < 0.001), as well as oxidative stress–related CLU, were increased. GGACT showed the greatest decrease (FC 0.30, p < 0.001), implicating altered energy metabolism. Conclusion: Distinct proteomic signatures at 5yrPT in DM/OB recipients highlight early mitochondrial, metabolic, immune, and extracellular matrix pathways involved in diabetic kidney disease. These changes precede clinical disease and identify candidate biomarkers and therapeutic targets to improve graft longevity.

ABSTRACT Background Adolescent and young adult (AYA) kidney transplant recipients (KTR) are susceptible to risk‐taking behaviors that peak during transfer from pediatric to adult healthcare, resulting in poorer outcomes. Professional guidelines support healthcare transition (HCT) practices to mitigate this risk; however, HCT perspectives and practices among providers, especially adult providers caring for KTR in the US, have not been widely studied. Methods An online survey of American Society of Transplantation (AST) members was conducted targeting both adult providers (AP) and pediatric providers (PP). Results The survey was completed by 135 respondents (predominantly US), including 61 PP and 74 AP. US respondents who disclosed their center ID represented 30% of all programs. Providers agreed that HCT was important (PP 97%, AP 94%) and a shared responsibility (PP 91% and AP 84%). Respondents to our survey frequently worked within transition programs (PP 70% vs. AP 48%), but the majority did not have a formal HCT policy to guide them (PP 43%, AP 21%). Multidisciplinary transition clinics were rare (PP 27%, AP 23%). Only 64% of PP included targeted HCT education either as part of a routine visit or a HCT session. Perceived barriers to providing HCT interventions were similar in both groups, including a lack of provider resources, outcomes tracking, provider communication, and patient/caregiver feedback. Conclusion Providers recognize the importance of HCT and the joint responsibility of PP and AP but have difficulty following best practices. A multipronged approach will be necessary to address barriers. Our survey reminds us of the gap that persists in providing AYAs with a seamless transfer from pediatric to adult care.

Background. Few studies have addressed immunosuppression management after allograft failure (AF). Immunosuppression withdrawal to minimize complications must be balanced with the risk of sensitization and potentially reduced retransplantation. We aimed to determine relationships between immunosuppression, death, sensitization, and retransplantation among patients with AF. Methods. We performed a single-center retrospective study of patients transplanted from October 2007 to May 2017 with AF. We collected data on demographics, immunosuppression, calculated panel reactive antibody (cPRA) levels, death, retransplantation, and dialysis. Cox regression models were used to evaluate factors associated with death and retransplantation. Results. From October 2007 to May 2017, 1354 solitary ABO-compatible transplants were performed, of which 97 failed. Ten percent of patients received a preemptive retransplant. Among those who returned to dialysis (n = 87), 35% died, 25% received another transplant, and 30% remained on dialysis. After AF, 46% of patients discontinued immunosuppression. The cPRA was unchanged if immunosuppression was maintained, but immunosuppression discontinuation was associated with increased cPRA from a median (interquartile range) of 18 (0–99) to 96 (88.5–100.0; P = 0.003). Age at failure (hazard ratio, 1.1; confidence interval, 1.0-1.1) and cardiovascular disease were associated with death (hazard ratio, 2.9; confidence interval, 1.2-7.0) in multivariate analysis. Importantly, immunosuppression maintenance was not associated with increased death or retransplantation despite the increase in cPRA that occurred when immunosuppression was discontinued. Conclusions. Kidney transplant recipients with AF have a high mortality rate after dialysis initiation. Although immunosuppression withdrawal was associated with increased cPRA, it was not associated with reduced retransplantation. Therefore, it is reasonable to discontinue immunosuppression after AF despite sensitization if retransplantation is delayed.

Background. Nephrolithiasis in living kidney donors is concerning due to the potential impact on long-term postdonation kidney function. Methods. We performed a cohort study of living kidney donors from 2 centers with a baseline computed tomography scan and implantation renal biopsy. Donors (>5 y since donation) completed a follow-up survey or underwent chart review to assess eGFR and incident hypertension. Stone formers were classified as symptomatic if they had a past symptomatic episode or asymptomatic if only incidental radiographic kidney stones were identified during donor evaluation. We compared baseline clinical, imaging, and biopsy characteristics by stone former status including review of metabolic evaluations in stone formers. Long-term risks of renal complications (low eGFR and hypertension) by stone former status were evaluated. Results. There were 12 symptomatic and 76 asymptomatic stone formers among 866 donors. Overall, baseline clinical characteristics and implantation biopsy findings were similar between stone formers and non-stone formers. After a median follow-up of 10 y, stone former status was not associated with eGFR <60 mL/min/1.73 m2, eGFR <45 mL/min/1.73 m2, or hypertension. Conclusions. Both asymptomatic and symptomatic SF have favorable histology findings at baseline. Long-term kidney outcomes were favorable in select stone formers with no evident increased long-term risk for decreased kidney function or hypertension after donation.

Background. Improving both patient and graft survival after kidney transplantation are major unmet needs. The goal of this study was to assess risk factors for specific causes of graft loss to determine to what extent patients who develop either death with a functioning graft (DWFG) or graft failure (GF) have similar baseline risk factors for graft loss. Methods. We retrospectively studied all solitary renal transplants performed between January 1, 2006, and December 31, 2018, at 3 centers and determined the specific causes of DWFG and GF. We examined outcomes in different subgroups using competing risk estimates and cause-specific Cox models. Results. Of the 5752 kidney transplants, graft loss occurred in 21.6% (1244) patients, including 12.0% (691) DWFG and 9.6% (553) GF. DWFG was most commonly due to malignancy (20.0%), infection (19.7%), cardiac disease (12.6%) with risk factors of older age and pretransplant dialysis, and diabetes as the cause of renal failure. For GF, alloimmunity (38.7%), glomerular diseases (18.6%), and tubular injury (13.9%) were the major causes. Competing risk incidence models identified diabetes and older recipients with higher rates of both DWFG and nonalloimmune GF. Conclusions. These data suggest that at baseline, 2 distinct populations can be identified who are at high risk for renal allograft loss: a younger, nondiabetic patient group who develops GF due to alloimmunity and an older, more commonly diabetic population who develops DWFG and GF due to a mixture of causes—many nonalloimmune. Individualized management is needed to improve long-term renal allograft survival in the latter group.

AbstractBackgroundThe medium‐ to long‐term outcomes of living kidney donors with hypertension compared to normotensive donors are not well understood, especially with the recent changes in hypertension guidelines.MethodsWe studied a cohort of 950 living kidney donors using different definitions of hypertension based on either ≥140/90 or ≥130/80 mmHg thresholds and based on either office or ambulatory blood pressure readings. Microstructural features on kidney biopsy at the time of donation were compared using different definitions of hypertension.ResultsAfter adjusting for years of follow‐up, age, sex, and baseline eGFR, hypertension (by any definition) did not significantly predict an eGFR < 45 ml/min/1.73 m2 at a median follow‐up of 10 years postdonation, though there was a borderline association with ambulatory blood pressure ≥ 130/80 mmHg predicting a 40% decline in eGFR (OR = 1.53, 1.00–2.36; p = .051). Proteinuria was predicted by office blood pressure ≥ 140/90 mmHg and by nondipper profile on nocturnal ambulatory blood pressure measurements. At the time of donation, larger glomeruli and arterial hyalinosis on biopsy were associated with hypertension defined by either ≥140/90 or ≥130/80 mmHg (by office or ambulatory measurements). Nocturnal nondipper status was associated with larger glomeruli size but not arteriolar hyalinosis when compared to dippers.ConclusionsIn programs that accept donors with controlled hypertension, various definitions of hypertension are associated with histological findings in the donated kidney, but none predict a clinically significant decline in kidney function 10 years after donation. These data support allowing healthy individuals with controlled hypertension to donate a kidney. However, donors with office hypertension (≥140/90 mmHg) and nondippers (regardless of hypertension status) are at greater long‐term risk for proteinuria, and particularly for these donors, longer follow‐up is warranted.

Background. At 5 and 10 y after kidney transplantation, chronic histologic changes such as arteriolar hyalinosis and mesangial expansion are common; however, determining cause is difficult. We compared surveillance biopsies in living donor kidney transplants (LDKTx) from HLA-matched siblings (termed HLA-identical [HLA-ID]) with HLA non-ID to investigate which histologic changes were likely due to alloimmune injury and which were due to nonalloimmune injury. Methods. We performed a retrospective, cohort study comparing HLA-ID sibling LDKTx (n = 175) with HLA non-ID LDKTx (n = 175; matched for age, sex, and year of transplant ±2 y) performed at a single institution from March 1999 to November 2018. Results. Baseline characteristics and maintenance immunosuppression were similar. Mortality rates were similar, but in the HLA-ID group, 10-y death-censored graft survival was higher (93.8% versus 80.9% HLA non-ID LDKTx; P < 0.001), rejection rates were lower (after 1 y 9.6% versus 27.1%; P < 0.001), and Banff inflammation scores including glomerulitis and peritubular capillaritis were lower on surveillance biopsies at 1, 5, and 10 y. In contrast, chronic Banff scores (interstitial fibrosis, arteriolar hyalinosis, mesangial expansion, etc) were similar in prevalence and severity on surveillance biopsies at 1, 5, and 10 y. Conclusions. HLA-ID LDKTx have less inflammation and less transplant glomerulopathy, but most chronic histologic changes were similar to less well-matched LDKTx. We conclude that these types of chronic changes are not associated with HLA mismatches and may be due to nonimmunologic causes (hypertension, obesity, etc), suggesting that new management approaches to prevent these lesions may be needed.

AbstractDeath with a functioning graft and death‐censored renal allograft failure remain major problems for which effective preventative protocols are lacking. The retrospective cohort study aimed to determine whether histologic changes on a 5‐year surveillance kidney biopsy predict adverse outcomes after transplantation in recipients who had: both Type 2 diabetes (T2DM) and obesity (BMI ≥ 30 kg/m2) at the time of transplantation (T2DM/Obesity, n = 75); neither (No T2DM/No obesity, n = 78); No T2DM/Obesity (n = 41), and T2DM/No obesity (n = 47). On 5‐year biopsies, moderate‐to‐severe mesangial expansion was more common in the T2DM/Obesity group (Banff mm score ≥2 = 49.3%; Tervaert classification MS ≥ 2b = 26.7%) compared to the other groups (p < .001 for both scores). Risk factors included older age, higher BMI, HbA1C, and triglycerides at 1‐year post‐transplant. Moderate‐to‐severe mesangial expansion correlated with death with function (HR 1.74 (1.01, 2.98), p = .045 Banff and 1.89 (1.01, 3.51) p = .045 Tervaert) and with death‐censored graft loss (HR 3.2 (1.2, 8.8), p = .02 Banff and HR 3.8 (1.3, 11.5), p = .01 Tervaert) over a mean of 11.6 years of recipient follow‐up post‐transplant. These data suggest that mesangial expansion in recipients with T2DM and obesity may reflect systemic vascular injury and might be a novel biomarker to predict adverse outcomes post renal transplant.

Significance Statement The quality of a kidney obtained from a living donor is often inferred from the donor’s age, risk factors, and kidney function. Little is known about the influence of a donated kidney’s structural features on the risk of death-censored graft failure in the recipient. In an analysis of 2293 kidney donor-recipient pairs, the authors identified subclinical nephrosclerosis, larger nephron size (but not nephron number), and smaller medullary volume as structural predictors of death-censored graft failure that were independent of both donor and recipient clinical characteristics. These findings provide important insights into the factors that define the “intrinsic quality” of the living kidney donor graft at the time of donation, and support use of intraoperative biopsies to identify donor kidneys that are at higher risk for failure. Background Nephrosclerosis, nephron size, and nephron number vary among kidneys transplanted from living donors. However, whether these structural features predict kidney transplant recipient outcomes is unclear. Methods Our study used computed tomography (CT) and implantation biopsy to investigate donated kidney features as predictors of death-censored graft failure at three transplant centers participating in the Aging Kidney Anatomy study. We used global glomerulosclerosis, interstitial fibrosis/tubular atrophy, artery luminal stenosis, and arteriolar hyalinosis to measure nephrosclerosis; mean glomerular volume, cortex volume per glomerulus, and mean cross-sectional tubular area to measure nephron size; and calculations from CT cortical volume and glomerular density on biopsy to assess nephron number. We also determined the death-censored risk of graft failure with each structural feature after adjusting for the predictive clinical characteristics of donor and recipient. Results The analysis involved 2293 donor-recipient pairs. Mean recipient follow-up was 6.3 years, during which 287 death-censored graft failures and 424 deaths occurred. Factors that predicted death-censored graft failure independent of both donor and recipient clinical characteristics included interstitial fibrosis/tubular atrophy, larger cortical nephron size (but not nephron number), and smaller medullary volume. In a subset with 12 biopsy section slides, arteriolar hyalinosis also predicted death-censored graft failure. Conclusions Subclinical nephrosclerosis, larger cortical nephron size, and smaller medullary volume in healthy donors modestly predict death-censored graft failure in the recipient, independent of donor or recipient clinical characteristics. These findings provide insights into a graft’s “intrinsic quality” at the time of donation, and further support the use of intraoperative biopsies to identify kidney grafts that are at higher risk for failure.

Background. Glucagon-like peptide-1 receptor agonists (GLP1RA) have been shown to improve glucose control and diabetes-related comorbidities in patients without solid organ transplants. The effectiveness, safety, and tolerability of GLP1RA after kidney transplantation have not been adequately studied. Methods. We retrospectively reviewed data on kidney transplant recipients performed in our institution, who were initiated on GLP1RA either for the treatment of type 2 diabetes diagnosed before transplantation or posttransplant diabetes. We analyzed efficacy, safety, and the effect on kidney allograft function. Results. Seventeen kidney transplant recipients were initiated on GLP1RA therapy, 14 of which remained on the medication for at least 12 months. The use of GLP1RA had no significant impact on weight loss, but was associated with a significant reduction in the total daily insulin dose, from the median of 63 [interquartile range 43-113] IU to 44 [interquartile range 25-88] and reduction in the risk of hypoglycemia in patients who were on therapy for at least approximately 12 months. Kidney function remained stable and none of the recipients experienced acute rejection. Tacrolimus dose was not significantly changed. Five patients (29%) discontinued GLP1RA therapy—4 due to side effects and 1 due to uncontrolled hyperglycemia. Conclusions. GLP1RA may be a relatively safe and effective treatment for kidney transplant recipients with type 2 diabetes that allows for a reduction in insulin requirements. More studies are needed to determine whether the use of these agents will translate into an improvement in allograft and patient survival.