Decline In Graft Function Research Articles

Pretransplant Cognitive Function and Kidney Transplant Outcomes: A Prospective Cohort Study

Background and hypothesisCognitive impairment is common in patients being evaluated for a kidney transplant (KT). The association between pre-transplant cognitive function and post-transplant outcomes is unclear. Study DesignWe performed a prospective cohort study to assess the association between pre-transplant cognitive function and clinically relevant post-transplant outcomes. Setting and PopulationIn this single center study, participants from the transplant clinic were evaluated during their pre-transplant clinic visits and followed prospectively. OutcomesOur primary outcome measure was allograft function. Secondary outcomes were length of hospitalization for KT, hospital readmission within 30 and 90 days, graft loss, graft rejection within 90 days and one year, and mortality. Analytic approachWe measured cognitive function with the Montreal Cognitive Assessment (MoCA) test. We assessed the association of pre-transplant MoCA score with post-transplant outcomes; we used linear mixed effects models to assess the association with the change in estimated glomerular filtration rate (eGFR), Poisson regression for length of hospitalization, Cox proportional hazard model for graft loss and mortality, and a logistic regression model for readmission and rejection. ResultsWe followed 501 participants for 2.7±1.5 years. The mean age of the patients was 53±14 years and the mean pre-transplant MoCA score was 25±3. Lower pre-transplant MoCA scores did not adversely affect the primary outcome of allograft function or the secondary outcomes. Although higher MoCA scores predicted a higher decline in graft function (β -0.28, 95% CI -0.55, -0.01, p= 0.04), the effect was small and not clinically significant. Older age was associated with longer hospitalization, lower likelihood of rejection, and higher mortality. Deceased donor KT (vs. living donor KT) was associated with longer hospitalization but better graft function. Longer time on dialysis prior to KT was associated with longer hospitalization. A history of diabetes mellitus was associated with higher mortality. LimitationsSingle center study limiting generalizability. ConclusionsPre-transplant MoCA scores were not associated with the primary outcome of allograft function or the secondary outcomes.

FOS+ Macrophages Promote Chronic Rejection of Cardiac Transplantation.

Chronic rejection remains the leading cause of progressive decline in graft function. Accumulating evidence indicates that macrophages participate in chronic rejection dependent on CD40-CD40L. The FOS family members are critical in inflammatory and immune responses. However, the mechanisms underlying the role of FOS family members in chronic rejection remain unclear. In this study, we aimed to elucidate the role and underlying mechanisms of FOS-positive macrophages regulated by CD40 that mediate chronic allograft rejection. We downloaded publicly accessible chronic rejection kidney transplant single-cell sequencing datasets from the gene expression omnibus database. Differentially expressed genes between the CD40hi and CD40low macrophage chronic rejection groups were analyzed. We established a chronic rejection mouse model by using CTLA-4-Ig. We treated bone marrow-derived macrophages with an anti-CD40 antibody. We assessed expression of the FOS family by flow cytometry, real-time quantitative polymerase chain reaction, Western blotting, and immunofluorescence. We identified altered signaling pathways by using RNA sequencing analysis. We detected DNA specifically bound to transcription factors by using ChIP-sequencing, with detection of the degree of graft fibrosis and survival. FOS was highly expressed on CD40hi macrophages in patients with chronic transplantrejection. Mechanistically, we showed that CD40 activated NF-κB2 translocation into the nucleus to upregulate c-Fos and FosB expression, thus promoting chronic rejection of cardiac transplant.We showed thatNF-κB2 regulated c-Fos and FosB expression by binding to the c-fos and fosb promoter regions. Inhibition of c-Fos/activator protein-1 decreased graft fibrosis and prolonged graft survival. CD40 may activate transcription factor NF-κB2 translocation into the nucleus of macrophages to upregulate c-Fos and FosB expression, thus promoting chronic rejection of cardiac transplant. Inhibition of c-Fos/activator protein-1 decreased grafts fibrosis and prolonged graft survival.

#1985 Tocilizumab in chronic active antibody-mediated rejection: a randomized controlled open-label multi-center trial (INTERCEPT study)

Abstract Background and Aims Chronic active antibody mediated graft rejection (caAMR) caused by immune-mediated injury is the leading cause of long-term graft loss in kidney transplant recipients. Nevertheless, no effective treatment exists for caAMR to date, highlighting a great unmet need for evaluation of novel treatment options. Recently, tocilizumab (TCZ), a monoclonal antibody directed against the human interleukin-6 (IL-6) receptor, by antagonizing IL-6-triggered inflammation and B cell/plasma cell-driven immune activation, has shown promise in the treatment of caAMR. However, TCZ has not been assessed systematically in a randomized study. The INTERCEPT study aims to evaluate the efficacy of addition of TCZ to standard of treatment (SOC) as compared to SOC alone in reducing the decline of graft function from baseline at 24 months after start of treatment as assessed by estimated glomerular filtration rate (eGFR) in kidney transplant recipients with caAMR. Method This ongoing randomized controlled open-label multi-center investigator-initiated trial plans to include a total of 50 adult kidney transplant recipients with biopsy-proven caAMR using Banff 2019 criteria at least 12 months after transplantation and eGFR ≥20 ml/min/1.73 m2. Any subject who underwent kidney transplantation in Sweden or is currently living in Sweden and being followed up at any of the Swedish transplant centers or their affiliated regional centers can be considered for participation. Participants are randomized to receive either TCZ (n=25) added to our standard of care (SOC) maintenance treatment or SOC alone (n=25) for a period of 24 months and followed for additional 12 months after cessation of the study medication. After the inclusion transplant biopsy at baseline, protocol biopsies are performed at 12 and 24 months. The study design flow-chart is shown in the Figure. The primary endpoint is the slope of eGFR at 24 months after start of treatment. The eGFR is assessed using Modification of Diet in Renal Disease (MDRD) formula. The secondary endpoints include assessment of the following at 12, 24 and 36 months: composite risk score iBox, safety, evolution and characteristics of donor-specific antibodies (DSA), graft histology, proteinuria, kidney function assessed by measured GFR (mGFR), patient- and death-censored graft survival, patient-reported outcomes that include transplant-specific well-being, adherence to immunosuppressive medications and perceived threat of the risk of graft rejection. Results We expect that addition of TCZ to SOC will slow down the decline of graft function in kidney transplant recipients with caAMR. Conclusion Currently there is no effective treatment for caAMR. Based on the hypothesis that inhibition of IL-6 by TCZ will reduce antibody production and reduce antibody-mediated damage, our randomized trial has a potential to provide evidence for a novel treatment strategy for caAMR. If TCZ is found to be effective, our study has the potential to improve long-term graft survival and quality of life, reduce morbidity and mortality in kidney transplant patients as well as lower the health care costs.

Tocilizumab in chronic active antibody-mediated rejection: rationale and protocol of an in-progress randomized controlled open-label multi-center trial (INTERCEPT study)

BackgroundChronic active antibody-mediated rejection (caAMR) in kidney transplants is associated with irreversible tissue damage and a leading cause of graft loss in the long-term. However, the treatment for caAMR remains a challenge to date. Recently, tocilizumab, a recombinant humanized monoclonal antibody directed against the human interleukin-6 (IL-6) receptor, has shown promise in the treatment of caAMR. However, it has not been systematically investigated so far underscoring the need for randomized controlled studies in this area.MethodsThe INTERCEPT study is an investigator-driven randomized controlled open-label multi-center trial in kidney transplant recipients to assess the efficacy of tocilizumab in the treatment of biopsy-proven caAMR. A total of 50 recipients with biopsy-proven caAMR at least 12 months after transplantation will be randomized to receive either tocilizumab (n = 25) added to our standard of care (SOC) maintenance treatment or SOC alone (n = 25) for a period of 24 months. Patients will be followed for an additional 12 months after cessation of study medication. After the inclusion biopsies at baseline, protocol kidney graft biopsies will be performed at 12 and 24 months. The sample size calculation assumed a difference of 5 ml/year in slope of estimated glomerular filtration rate (eGFR) between the two groups for 80% power at an alpha of 0.05.The primary endpoint is the slope of eGFR at 24 months after start of treatment. The secondary endpoints include assessment of the following at 12, 24, and 36 months: composite risk score iBox, safety, evolution and characteristics of donor-specific antibodies (DSA), graft histology, proteinuria, kidney function assessed by measured GFR (mGFR), patient- and death-censored graft survival, and patient-reported outcomes that include transplant-specific well-being, adherence to immunosuppressive medications and perceived threat of the risk of graft rejection.DiscussionNo effective treatment exists for caAMR at present. Based on the hypothesis that inhibition of IL-6 receptor by tocilizumab will reduce antibody production and reduce antibody-mediated damage, our randomized trial has a potential to provide evidence for a novel treatment strategy for caAMR, therewith slowing the decline in graft function in the long-term.Trial registrationClinicalTrials.gov NCT04561986. Registered on September 24, 2020

Salvage of a Transplanted Kidney following Immediate Renal Artery Narrowing

Renal transplantation is considered the preferred treatment method for chronic renal failure. Early graft failure caused by transplant renal artery narrowing/stenosis is a common vascular complication after kidney transplantation. The classic symptoms include refractory hypertension, a decline in graft function, and fluid retention. Color Doppler sonography plays an important role in the diagnosis of renal artery narrowing; however, allograft artery angiography remains the gold standard. We report on a case of cadaveric donor renal transplantation, wherein the urine output markedly decreased within 7 h of transplantation due to renal arterial narrowing and the efforts that were made to salvage the kidney.

BKPyV DNAemia in Kidney Transplant Recipients Undergoing Regular Screening: A Single-Centre Cohort Study.

Infection with BK polyomavirus (BKPyV) is a common opportunistic infection after kidney transplantation (KT) and may affect graft function. We aimed to determine the incidence, risk factors, and clinical outcomes of BKPyV DNAemia in a prospective cohort of 601 KT recipients transplanted from 2012 to 2020. BKPyV PCR on plasma was performed at days 60, 90, 180, 270, and 360 post-KT. Any BKPyV DNAemia was defined as a single BKPyV DNA of ≥1000 copies/mL. Severe BKPyV DNAemia was defined as two consecutive BKPyV DNA of ≥10,000 copies/mL. Cumulative incidences were investigated using the Aalen-Johansen estimator, and the risk factors were investigated in Cox proportional hazard models. The incidence of any BKPyV DNAemia and severe BKPyV DNAemia was 21% (18-25) and 13% (10-16) at one year post-KT, respectively. Recipient age > 50 years (aHR, 1.72; 95% CI 1.00-2.94; p = 0.049), male sex (aHR, 1.96; 95% CI 1.17-3.29; p = 0.011), living donors (aHR, 1.65; 95% CI 1.03-2.74; p = 0.045), and >3 HLA-ABDR mismatches (aHR, 1.72; 95% CI 1.01-2.94; p = 0.046) increased the risk of severe BKPyV DNAemia. Any BKPyV DNAemia was associated with an increased risk of graft function decline (aHR, 2.26; 95% CI 1.00-5.12; p = 0.049), and severe BKPyV DNAemia was associated with an increased risk of graft loss (aHR, 3.18; 95% CI 1.06-9.58; p = 0.039). These findings highlight the importance of BKPyV monitoring post-KT.

Natural killer cell functional genetics and donor-specific antibody-triggered microvascular inflammation

Antibody-mediated rejection (ABMR) is a leading cause of graft failure. Emerging evidence suggests a significant contribution of natural killer (NK) cells to microvascular inflammation (MVI). We investigated the influence of genetically determined NK cell functionality on ABMR development and activity. The study included 86 kidney transplant recipients subjected to systematic biopsies triggered by donor-specific antibody detection. We performed killer immunoglobulin-like receptor typing to predict missing self and genotyped polymorphisms determining NK cell functionality (FCGR3AV/F158 [rs396991], KLRC2wt/del, KLRK1HNK/LNK [rs1049174], rs9916629-C/T). Fifty patients had ABMR with considerable MVI and elevated NK cell transcripts. Missing self was not related to MVI. Only KLRC2wt/wt showed an association (MVI score: 2 [median; interquartile range: 0-3] vs 0 [0-1] in KLRC2wt/del recipients; P = .001) and remained significant in a proportional odds multivariable model (odds ratio, 7.84; 95% confidence interval, 2.37-30.47; P = .001). A sum score incorporating all polymorphisms and missing self did not outperform a score including only KLRC2 and FCGR3A variants, which were predictive in univariable analysis. NK cell genetics did not affect graft functional decline and survival. In conclusion, a functional KLRC2 polymorphism emerged as an independent determinant of ABMR activity, without a considerable contribution of missing self and other NK cell gene polymorphisms.

Indoleamine 2,3-Dioxygenase 1 (IDO1) in Kidney Transplantation: A Guardian against Rejection.

Kidney transplantation is a crucial treatment for end-stage kidney disease, with immunosuppressive drugs helping to reduce acute rejection rates. However, kidney graft longevity remains a concern. This study explores the role of indoleamine 2,3-dioxygenase 1 (IDO1) in kidney transplant immunology. IDO1 breaks down tryptophan, affecting immune cell behavior, primarily T-cells. The research focuses on both cellular and antibody-mediated immune responses, often causing graft damage. The study assessed IDO1 expression in renal transplant biopsies from patients with graft function decline, examining its connection to clinical parameters. A total of 121 biopsy samples were evaluated for IDO1 expression using immunohistochemistry. Patients were categorized as IDO1(+) positive or IDO1(-) negative based on immunoreactivity in tubular epithelium. Results showed a significant link between IDO1 expression and rejection incidence. IDO1(+) positive patients had lower rejection rates (32.9%) compared to IDO1(-) negative ones (62.2%) [p = 0.0017], with substantial differences in antibody-mediated rejection (AMR) (5.2% vs. 20%) [p = 0.0085] and T-cell mediated rejection (TCMR) (31.6% vs. 57.8%). These associations suggest that IDO1 may play a protective role in kidney transplant rejection. IDO1 modulation could offer novel therapeutic avenues to enhance graft survival. The study underscores IDO1 as a potential marker for rejection risk assessment, with its potential applications in personalized interventions and improved patient outcomes. Further research is needed to fully comprehend the mechanisms behind IDO1's immunomodulatory functions and its potential clinical translation.

Current Evidence on Surgical Management for Benign Prostatic Hyperplasia in Renal Transplant Recipients: A Systematic Review.

Background: Patients who have undergone renal transplant may have a concomitant benign prostatic hyperplasia (BPH), a condition that can potentially hinder the recovery of the renal graft and necessitate surgical intervention. However, endoscopic treatment of BPH should be performed carefully because of the associated perioperative risks. We aimed to systematically assess the factors affecting surgical indications and perioperative outcomes of BPH surgical treatment in renal transplantation (RT) recipients. Methods: A systematic literature search was performed on January 28, 2023, using Scopus, PubMed, and EMBASE with no date limit. Preclinical and animal studies, reviews, letters to the editor, case reports, and meeting abstracts were excluded. Results: Eighteen articles were accepted and included. Clinical BPH has a high incidence rate after RT, particularly in elderly men. Secondary events associated with BPH, such as acute urinary retention and urinary tract infections, can lead to a gradual decline of renal graft function and patient survival. BPH procedure can prevent these events and guarantee improvements in serum creatinine levels, voiding parameters, and lower urinary tract symptoms. When the urine culture is negative, the endoscopic procedure of the prostate may be performed within 1 month of the initial procedure, particularly in older patients, more prone to develop voiding dysfunction. Alternatively, a transurethral incision of the prostate may be recommended for patients with smaller prostates who wish to preserve ejaculatory function. Data on comparative BPH surgical procedures are lacking. Conclusions: BPH procedure should be offered in RT recipients who develop bladder outlet obstruction owing to BPH. Endoscopic treatment should be performed after a few weeks from RT to avoid further graft deterioration.

Pattern of biochemical markers of mineral and bone disorders in kidney transplant recipients: real-world data

There is a lack of studies providing comprehensive data on the prevalence of mineral and bone disorders (MBD) laboratory abnormalities after kidney transplantation in Russia. to obtain real-world data on the prevalence of the main mineral abnormalities among kidney transplant recipients and to revise their concomitant MBD therapy. This cross-sectional study included 236 patients with successful kidney transplantation. Their serum intact parathyroid hormone (iPTH), total calcium (Ca), phosphorus (P), and alkaline phosphatase (ALP) levels were measured. Only 6.2% of our cohort had all laboratory parameters within the target range, whereas persistent HPT along with hypercalcemia was noted in almost one third of the patients (31%). Normal iPTH levels were observed in 13% cases; 84% of the patients had hyperparathyroidism. The fraction of patients with target iPTH did not differ between the groups with normal and decreased estimated glomerular filtration rate (eGFR) (p=0.118). Hypercalcemia was observed in 29% cases. The serum P level varied significantly in groups with different eGFR (p<0.0001), increasing with declining graft function. Furthermore, 40.7% of patients had ALP above the target range. While 123 patients received active vitamin D (alfacalcidol), 33 received monotherapy with inactive vitamin D (cholecalciferol). The control group consisted of 57 medication-naïve patients. The serum total Ca level varied significantly between the groups (p=0.0006), being higher in patients supplemented with cholecalciferol. The fraction of patients with normocalcemia was lowest in the cholecalciferol group (chi-square, р=0.0018). The prevalence of biochemical abnormalities after kidney transplantation is high. Alfacalcidol usage may be safer than using cholecalciferol to prevent hypercalcemia development.

A Case Report of a Kidney Transplant Recipient With Organizing Pneumonia After Graft Loss

We present a case of a 68-year-old male patient who underwent ABO-incompatible living kidney transplantation from his wife because of immunoglobulin A nephropathy 13 years ago. Over time, the patient showed a gradual decline in graft function and required reinitiation of hemodialysis because of fluid overload, which led to his admission to our hospital. An arteriovenous fistula was created, and subsequently, hemodialysis therapy was started. Because he had chronic cytomegalovirus retinopathy and thrombotic microangiopathy due to immunosuppressive therapy at admission, mycophenolate mofetil and tacrolimus were discontinued during hemodialysis initiation. Only low-dose prednisolone was continued. One week later, the patient had a fever, and chest computed tomography revealed bilateral pneumonia, which was not improved by antibiotics. The patient was diagnosed with organized pneumonia. After ruling out opportunistic infection, including pneumocystis pneumonia, increased doses of prednisolone resulted in the remission of organizing pneumonia.

Appointment Nonadherence and Graft Outcomes in Living Donor Kidney Transplantation

Medication nonadherence is associated with worse graft outcomes but is hard to recognize in clinical settings due to its self-reporting nature. We hypothesized that appointment nonadherence might be associated with worse graft outcomes in living donor kidney transplantation. We included 167 adult living-donor kidney transplants whose grafts survived >2 years from April 2011 to May 2020. Thirty-two cases of appointment nonadherence were identified and compared with the controls (n=135). Younger age, male sex, higher body weight, and parent donor were significantly observed in the appointment nonadherence group. The appointment nonadherence group was significantly associated with worse graft survival (5 years: 82.3% vs 98.9%, P < .001, 10 years: 67.2% vs 89.6%, P < .001), de novo donor-specific antibody production, acute rejection, as well as the decline of graft function. Furthermore, appointment nonadherence had a 4-fold higher risk of graft loss after an adjustment with recipient age, sex, body weight, and donor type (adjusted hazard ratio: 3.93, 95% CI: 1.15-13.42, P=.029). Appointment nonadherence might be an alternative predictor for worse graft outcomes after living donor kidney transplantation.

Sodium bicarbonate for kidney transplant recipients with metabolic acidosis in Switzerland: a multicentre, randomised, single-blind, placebo-controlled, phase 3 trial

Metabolic acidosis is common in kidney transplant recipients and is associated with declining graft function. Sodium bicarbonate treatment effectively corrects metabolic acidosis, but no prospective studies have examined its effect on graft function. Therefore, we aimed to test whether sodium bicarbonate treatment would preserve graft function and slow the progression of estimated glomerular filtration rate (GFR) decline in kidney transplant recipients. The Preserve-Transplant Study was a multicentre, randomised, single-blind, placebo-controlled, phase 3 trial at three University Hospitals in Switzerland (Zurich, Bern, and Geneva), which recruited adult (aged ≥18 years) male and female long-term kidney transplant recipients if they had undergone transplantation more than 1 year ago. Key inclusion criteria were an estimated GFR between 15 mL/min per 1·73 m2 and 89 mL/min per 1·73 m2, stable allograft function in the last 6 months before study inclusion (<15% change in serum creatinine), and a serum bicarbonate of 22 mmol/L or less. We randomly assigned patients (1:1) to either oral sodium bicarbonate 1·5-4·5 g per day or matching placebo using web-based data management software. Randomisation was stratified by study centre and gender using a permuted block design to guarantee balanced allocation. We did multi-block randomisation with variable block sizes of two and four. Treatment duration was 2 years. Acid-resistant soft gelatine capsules of 500 mg sodium bicarbonate or matching 500 mg placebo capsules were given at an initial dose of 500 mg (if bodyweight was <70 kg) or 1000 mg (if bodyweight was ≥70 kg) three times daily. The primary endpoint was the estimated GFR slope over the 24-month treatment phase. The primary efficacy analyses were applied to a modified intention-to-treat population that comprised all randomly assigned participants who had a baseline visit. The safety population comprised all participants who received at least one dose of study drug. The trial is registered with ClinicalTrials.gov, NCT03102996. Between June 12, 2017, and July 10, 2019, 1114 kidney transplant recipients with metabolic acidosis were assessed for trial eligibility. 872 patients were excluded and 242 were randomly assigned to the study groups (122 [50%] to the placebo group and 120 [50%] to the sodium bicarbonate group). After secondary exclusion of two patients, 240 patients were included in the intention-to-treat analysis. The calculated yearly estimated GFR slopes over the 2-year treatment period were a median -0·722 mL/min per 1·73 m2 (IQR -4·081 to 1·440) and mean -1·862 mL/min per 1·73 m2 (SD 6·344) per year in the placebo group versus median -1·413 mL/min per 1·73 m2 (IQR -4·503 to 1·139) and mean -1·830 mL/min per 1·73 m2 (SD 6·233) per year in the sodium bicarbonate group (Wilcoxon rank sum test p=0·51; Welch t-test p=0·97). The mean difference was 0·032 mL/min per 1·73 m2 per year (95% CI -1·644 to 1·707). There were no significant differences in estimated GFR slopes in a subgroup analysis and a sensitivity analysis confirmed the primary analysis. Although the estimated GFR slope did not show a significant difference between the treatment groups, treatment with sodium bicarbonate effectively corrected metabolic acidosis by increasing serum bicarbonate from 21·3 mmol/L (SD 2·6) to 23·0 mmol/L (2·7) and blood pH from 7·37 (SD 0·06) to 7·39 (0·04) over the 2-year treatment period. Adverse events and serious adverse events were similar in both groups. Three study participants died. In the placebo group, one (1%) patient died from acute respiratory distress syndrome due to SARS-CoV-2 and one (1%) from cardiac arrest after severe dehydration following diarrhoea with hypotension, acute kidney injury, and metabolic acidosis. In the sodium bicarbonate group, one (1%) patient had sudden cardiac death. In adult kidney transplant recipients, correction of metabolic acidosis by treatment with sodium bicarbonate over 2 years did not affect the decline in estimated GFR. Thus, treatment with sodium bicarbonate should not be generally recommended to preserve estimated GFR (a surrogate marker for graft function) in kidney transplant recipients with chronic kidney disease who have metabolic acidosis. Swiss National Science Foundation.

Impact of Blood Pressure Control on Graft Survival in Kidney Transplant Recipients

Cardiovascular disease is the primary driver of morbidity and mortality in kidney transplant recipients. Hypertension is an important risk factor for development of cardiovascular disease in this population. Despite its important role in post-transplant outcomes, the blood pressure goals for kidney transplant recipients remain elusive. Current guidelines are based on observational data or data extrapolated from the chronic kidney disease population. We followed 5-year blood pressure control of 378 kidney-alone transplant recipients at a single center and evaluated patient survival, graft survival, proteinuria, and rate of decline of kidney graft function. We found that a mean systolic blood pressure (BP) of 121 to 130 mm Hg was associated with better graft survival, slower decline of kidney allograft function, and lower degree of proteinuria when compared with a mean systolic BP ≤120 or >130 mm Hg. This study provides evidence for strict blood pressure control, systolic BP between 121 and 130 mm Hg, and also cautions against intensive control of systolic BP <120 mm Hg in kidney transplant recipients.

Synthesis of siRNA-Conjugated Dextran-Coated Iron Oxide Nanoparticles for Islet Protection During Transplantation and Noninvasive Imaging.

Pancreatic islet transplantation (Tx) has a lifesaving potential for type 1 diabetes (T1D) patients. Islet damage during and after transplantation is one of the major reasons hampering its wide clinical application. Inability to monitor transplanted islets also severely limits our understanding of mechanisms regarding declining graft function after transplantation. Our team has proposed to use magnetic nanoparticles conjugated to siRNA (MN-siRNA) to label islets prior to transplantation with two goals in mind: to protect them from damage by silencing harmful genes and to monitor them after transplantation using noninvasive magnetic resonance imaging (MRI). This manuscript provides a step-by-step protocol for the synthesis and characterization of MN-siRNA probes.

316.14: Impact of Donor Hepatic Steatosis on Kidney Transplant Recipient Outcomes

Introduction: Increasing evidence suggests an independent association of hepatic steatosis with chronic kidney disease, kidney function decline and risk of cardiovascular (CV) disease. Whether the presence or severity of an organ donor’s hepatic steatosis impacts on kidney transplant recipient (KTR) outcomes has not been studied. Methods: We performed a retrospective cohort study of deceased liver donors, matched to their KTR, in New South Wales (NSW), Australia from 2006-2020. We linked data from the Australian and New Zealand Dialysis and Transplantation (ANZDATA) and Organ Donation (ANZOD) registries with biopsy results of donor livers evaluated or utilised for transplantation at the NSW state-wide liver transplant unit. Donor hepatic steatosis was graded contemporaneously by histopathologists as S0 (<5%), S1 (5-33%), S2 (>33-66%) or S3 (>66%). Standard donor and recipient characteristics were collected. All-cause death, cardiovascular (CV) death, graft loss (death-censored), delayed graft function (DGF), graft function decline (assessed by eGFR) and post-transplant CV events (composite of coronary artery, peripheral vascular or cerebrovascular disease) were compared among recipients according to their presence and severity of hepatic steatosis. Results: 751 donors with liver biopsies were matched to 1,263 KTRs (8,043 person-years follow-up). Donor hepatic steatosis grades were: S0 453 (60%), S1 195 (26%), S2 71 (9%), S3 32 (4%). Donors with hepatic steatosis (S1-3) were significantly older (median age 53 vs 46 years) than those without steatosis and had worse metabolic profiles: higher body mass index (median 27 vs 25kg/m2), diabetes (9% vs 6%), hypertension (35% vs 25%). KTR of donors with and without hepatic steatosis had similar baseline characteristics. Presence of hepatic steatosis (vs no steatosis) and steatosis severity (S3 vs S0-2) did not impact on all-cause- or CV-death, graft loss, or DGF in the multivariable analysis. Univariable analysis suggested that decline in graft function was greater in recipients from donors with steatosis compared to recipients of donors without steatosis, but this no longer remained significant on multivariable analysis after adjusting for other variables. There was an increased risk of CV events on univariable (HR 1.42, 95%CI 1.00-2.02, p=0.05) and multivariable analysis (HR 1.47, 95%CI 1.03-2.10, p=0.04, Table 1) among recipients of donors with severe (S3) steatosis versus those with no/less donor steatosis. Conclusion: In this retrospective analysis, neither the presence nor severity of biopsy-proven donor hepatic steatosis appeared to impact kidney transplant recipient outcomes. Recipients from donors with severe hepatic steatosis may be at higher risk of cardiovascular events.

232.7: Elevated Donor-Derived Cell-Free DNA Associates With Subsequent Decline of Allograft Function

Introduction: Donor-derived cell-free DNA (dd-cfDNA) emerged as a candidate biomarker for detecting graft injury, particularly from antibody-mediated rejection, and is currently proposed to complement donor-specific antibodies (DSAs) as an alloimmune-mediated injury surveillance method. We sought to investigate the impact of an initial increase of dd-cfDNA level on subsequent decline in graft function. Materials: The study included all kidney transplant (KT) recipients that underwent dd-cfDNA testing as part of their clinical care between September 2017 and December 2019 at our center. Only patients with a follow-up of at least 12 months were included in this analysis. An elevated dd-cfDNA was defined as a level over 0.5%. Results: Of the 171 KT recipients tested for dd-cfDNA, 49 were followed for at least 12 months since initial testing. The study cohort had an initial serum creatinine and eGFR of 1.64 ± 0.58 mg/dl and 48 ± 21 ml/min/1.73m2, respectively. Overall, the absolute and percentual decline of eGFR were -0.12 ml/min/month (IQR, -0.43 to 0.56) and -4.26% (IQR, -20.5% to 17%), with 26.5% and 10.2% of patients having an eGFR decline of more than 15% and 30%, respectively. Fifteen patients (30.6%) had an elevated dd-cfDNA (over 0.5%) and had a similar baseline allograft function compared to those without an elevated dd-cfDNA level. After a median follow-up period of 15.3 months (IQR:13.6-19), patients with elevated dd-cfDNA had a faster decline of eGFR [absolute eGFR decline, -0.21 ml/min/month (IQR, -0.36 to 0.22); percentual GFR decline, -8.7% (IQR, -25% to 4.4%)], compared to those without elevated dd-cfDNA [absolute eGFR decline, +0.03 ml/min/month (IQR, -0.5 to 0.6); percentual GFR decline, +1.14% (IQR, -14% to 28%)](p=0.09)(Figure 1). Similarly, there was a tendency for a higher percentage of patients with elevated dd-cfDNA for a decline of eGFR greater than 15% (33.3% vs. 23.5%, p=0.5) or 30% (13.3% vs. 8.8%, p=0.6), respectively. In addition, patients with DSAs and an elevated dd-cfDNA showed a greater percentual eGFR decline (-9.1±16.5%), compared to those with DSAs and normal dd-cfDNA (+3.3±21.1%), or to those without DSAs and normal dd-cfDNA (+2.3±18.05%). In multivariable logistic regression analysis, an elevated dd-cfDNA level was independently associated with the subsequent percentual decline of eGFR (OR, 0.96; 95%CI, 0.93 to 1.00; p=0.05). Conclusion: We have shown that despite initial stable allograft function, a higher dd-cfDNA level associates with subsequent decline of eGFR. Thus, the initial identification of subclinical graft injury could associate with long-term graft outcomes, expanding the clinical utility of dd-cfDNA.

Levels of angiotensin II type-1 receptor antibodies and endothelin-1 type-A receptor antibodies correlate with antibody-mediated rejection and poor graft function in kidney-transplantation patients

ObjectiveAngiotensin II type-1 receptor antibodies (AT1R-Ab) and endothelin-1 type-A receptor antibodies (ETAR-Ab) are non-human leukocyte antigen (HLA) antibodies that can elicit adverse effects on kidney transplantation (KT) outcomes. We investigated the correlation between levels of AT1R-Ab and ETAR-Ab and postoperative outcomes in KT recipients. MethodsPre-KT and post-KT serum from 79 patients was collected. Post-KT serum was collected within 1 year after KT or simultaneously as the biopsy. Levels of AT1R-Ab and ETAR-Ab were measured using enzyme-linked immunosorbent assay kits. AT1R-Ab >17.0 U/mL and ETAR-Ab >10.0 U/mL was considered to denote positivity according to manufacturer recommendations. We measured donor-specific antibodies against human leukocyte antigens (HLA-DSA) levels using LABScreen™ single-antigen kits. ResultsSeventy-nine (54 men, 25 women) formed the study cohort. Seven (8.7%) patients were positive for AT1R-Ab, 25 (31.6%) patients were positive for both AT1R-Ab and ETAR-Ab, and 47 (59.5%) were negative for both antibodies at all time points. No patients died during the study period. Patients with both AT1R-Ab and ETAR-Ab were associated with a higher prevalence of antibody-mediated rejection (AMR) and lower estimated glomerular filtration rate, but not allograft loss or delayed graft function. AT1R-Ab were associated with T-cell-mediated rejection, but the association was not significant. HLA-DSA were associated significantly with a higher creatinine level in serum at 12 months and 24 months in patients with AT1R-Ab and/or ETAR-Ab. ConclusionsAT1R-Ab, ETAR-Ab, and HLA-DSA were associated with a higher prevalence of AMR and decline in graft function. Measurement of levels of AT1R-Ab and ETAR-Ab in KT patients may be useful for stratification of immunological risk and identification of patients at a high risk of adverse graft outcome.

Single-Cell Landscape of Mouse Islet Allograft and Syngeneic Graft.

Islet transplantation to treat the late stage of type 1 diabetic patient (T1DM) has recently made inspiring success in clinical trials. However, most patients experience a decline in islet graft function in one to three years due to immune rejection. Although the mechanisms of immune cells, including macrophages, dendritic cells (DCs), neutrophils, natural killer cells (NKs), B cells, and T cells, that mediate immune rejection have been investigated, the overall characteristics of immune infiltrates in islet allografts and syngeneic grafts remain unclear. Single-cell RNA sequencing (scRNA-seq) has provided us with new opportunities to study the complexity of the immune microenvironment in islet transplants. In the present study, we used scRNA-seq to comprehensively analyze the immune heterogeneity in the mouse model of islet transplantation. Our data revealed T lymphocytes and myeloid cells as the main immune components of grafts 7 days post-islet transplantation, especially in allografts. Moreover, our results indicated that allogeneic islet cells were transformed into antigen-presenting cell-like cells with highly expressed MHC class I molecules and genes involved in MHC class I-mediated antigen presentation. This transformation may dramatically facilitate the interaction with cytotoxic CD8+ T cells and promote the destruction of islet allografts. Our study provides insight into the transcriptomics and diverse microenvironment of islet grafts and their impacts on immune rejection.

Evolution of humoral lesions on follow-up biopsy stratifies the risk for renal graft loss after antibody-mediated rejection treatment.

The standard-of-care protocol, based on plasma exchanges, high-dose intravenous immunoglobulin and optimization of maintenance immunosuppression, can slow down the evolution of antibody-mediated rejection (AMR), but with high interindividual variability. Identification of a reliable predictive tool of the response to AMR treatment is a mandatory step for personalization of the follow-up strategy and to guide second-line therapies. Interrogation of the electronic databases of 2 French university hospitals (Lyon and Strasbourg) retrospectively identified 81 renal transplant recipients diagnosed with AMR without chronic lesions (cg score≤1) at diagnosis and for whom a follow-up biopsy had been performed 3-6 months after initiation of therapy. The evolution of humoral lesions on follow-up biopsy (disappearance versus persistence versus progression) correlated with the risk for allograft loss (logrank test, P=.001). Patients with disappearance of humoral lesions had ∼80% graft survival at 10 years. The hazard ratio for graft loss in multivariate analysis was 3.91 (P=.04) and 5.15 (P=.02) for patients with persistence and progression of lesions, respectively. The non-invasive parameters classically used to follow the intensity of humoral alloimmune response (evolution of immunodominant DSA mean fluorescence intensity) and the decline of renal graft function (estimated glomerular filtration rate decrease and persistent proteinuria) showed little clinical value to predict the histological response to AMR therapy. We conclude that invasive monitoring of the evolution of humoral lesions by the mean of follow-up biopsy performed 3-6 months after the initiation of therapy is an interesting tool to predict long-term outcome after AMR treatment.