Role of Shear Wave Elastography for Assessment of Renal-Allograft Fibrosis and its Correlation With Histopathology.

OBJECTIVES: To investigate whether shear wave elastography (SWE) can accurately identify interstitial fibrosis and tubular atrophy (IFTA) in chronic renal allograft injury (CRAI) and whether it can differentiate between different grades of IFTA. MATERIALS AND METHODS: Prospective observational study on renal transplant recipients who presented with CRAI. Patient selection was done on the basis of clinical presentation, serum creatinine, and eGFR levels. Biopsy and SWE were performed and SWE values were correlated with histopathological findings according to Banff schema. Receiver operating characteristic (ROC) was also analyzed to assess the diagnostic efficacy of SWE. RESULTS: Sxity-one patients were evaluated. Ten patients had no IFTA, 33 patients had mild IFTA, 16 patients had moderate IFTA, and 2 patients had severe IFTA. Mean parenchymal stiffness values in no IFTA, mild IFTA, moderate IFTA and severe IFTA were 39.86 ± 2.17 kPa (3.64 ± 0.09 m/s), 41.59 ± 3.36 kPa (3.71 ± 0.15 m/s), 47.59 ± 3.34 kPa (3.98 ± 0.14 m/s), and 53.83 ± 1.41 kPa (4.25 ± 0.03 m/s), respectively. SWE values of parenchymal stiffness reached statistical significance to differentiate between mild, moderate, and severe IFTA. ROC analysis revealed cut-off values of 45.09 kPa (3.89 m/s) to differentiate between mild IFTA and moderate IFTA, 52.06 kPa (4.18 m/s) to differentiate between moderate IFTA and severe IFTA with acceptable sensitivity and specificity. CONCLUSION: SWE is a non-invasive and cost-effective imaging tool to evaluate the disease status of renal allografts affected by CRAI. Thus, it can be of paramount importance if added to the regular follow-up imaging protocol of renal allograft along with grayscale and Doppler imaging.

Innate and adaptive effector immune drivers of cytomegalovirus disease in lung transplantation: a double-edged sword.

Up to 90% of the global population has been infected with cytomegalovirus (CMV), a herpesvirus that remains latent for the lifetime of the host and drives immune dysregulation. CMV is a critical risk factor for poor outcomes after solid organ transplant, though lung transplant recipients (LTR) carry the highest risk of CMV infection, and CMV-associated comorbidities compared to recipients of other solid organ transplants. Despite potent antivirals, CMV remains a significant driver of chronic lung allograft dysfunction (CLAD), re-transplantation, and death. Moreover, the extended utilization of CMV antiviral prophylaxis is not without adverse effects, often necessitating treatment discontinuation. Thus, there is a critical need to understand the immune response to CMV after lung transplantation. This review identifies key elements of each arm of the CMV immune response and highlights implications for lung allograft tolerance and injury. Specific attention is paid to cellular subsets of adaptive and innate immune cells that are important in the lung during CMV infection and reactivation. The concept of heterologous immune responses is reviewed in depth, including how they form and how they may drive tissue- and allograft-specific immunity. Other important objectives of this review are to detail the emerging role of NK cells in CMV-related outcomes, in addition to discussing perturbations in CMV immune function stemming from pre-existing lung disease. Finally, this review identifies potential mechanisms whereby CMV-directed treatments may alter the cellular immune response within the allograft.

Novel non-invasive method for urine mapping: Deep-learning-enabled SERS spectroscopy for the rapid differential detection of kidney allograft injury.

The kidney allograft has been under continuous attack from diverse injuries since the very beginning of organ procurement, leading to a gradual decline in function, chronic fibrosis, and allograft loss. It is vital to routinely and precisely monitor the risk of injuries after renal transplantation, which is difficult to achieve because the traditional laboratory tests lack sensitivity and specificity, and graft biopsies are invasive with the risk of many complications and time-consuming. Herein, a novel method for the diagnosis of graft injury is demonstrated, using deep learning-assisted surface-enhanced Raman spectroscopy (SERS) of the urine analysis. Specifically, we developed a hybrid SERS substrate composed of gold and silver with high sensitivity to the urine composition under test, eliminating the need for labels, which makes measurements easy to perform and meanwhile results in extremely abundant and complex Raman vibrational bands. Deep learning algorithms were then developed to improve the interpretation of the SERS spectral fingerprints. The deep learning model was trained with SERS signals of urine samples of recipients with different injury types including delayed graft function (DGF), calcineurin-inhibitor toxicity (CNIT), T cell-mediated rejection (TCMR), antibody-mediated rejection (AMR), and BK virus nephropathy (BKVN), which explored the features of these types and achieved the injury differentiation with an overall accuracy of 93.03%. The results highlight the potential of combining label-free SERS spectroscopy with deep learning as a method for liquid biopsy of kidney allograft injuries, which can provide great potential to diagnose and evaluate allograft injuries, and thus extend the life of kidney allografts.

Molecular diagnosis of antibody-mediated rejection: Evaluating biopsy-based transcript diagnostics in the presence of donor-specific antibodies but without microvascular inflammation, a single-center descriptive analysis.

Biopsy-based transcript diagnostics may identify molecular antibody-mediated rejection (AMR) when microvascular inflammation (MVI) is absent. In this single-center cohort, biopsy-based transcript diagnostics were validated in 326 kidney allograft biopsies. A total of 71 histological AMR and 35 T cell-mediated rejection (TCMR) cases were identified as molecular AMR and TCMR in 55% and 63%, respectively. Among 121 cases without MVI (glomerulitis + peritubular capillaritis = 0), 45 (37%) donor-specific antibody (DSA)-positive and 76 (63%) DSA-negative cases were analyzed. Twenty-one out of the 121 (17%) cases showed borderline changes, or TCMR, while BK nephropathy was excluded. None of the 45 DSA-positive patients showed molecular AMR. Among 76 DSA-negative patients, 2 had mixed molecular AMR/TCMR. All-AMR phenotype scores (sum of R4-R6) exhibited median values of 0.13 and 0.12 for DSA-positive and DSA-negative patients, respectively (P = .84). A total of 13% (6/45) DSA-positive and 11% (8/76) DSA-negative patients showed an all-AMR phenotype score > 0.30 (P = .77). Patients with a higher all-AMR phenotype score showed 33% more histologic TCMR (P = .005). The median all-AMR phenotype scores of glomerular basement membrane double contours = 0 and glomerular basement membrane double contours > 0 biopsies were 0.12 and 0.10, respectively (P = .35). Biopsy-based transcript diagnostics did not identify molecular AMR in cases without MVI. Follow-up biopsies and outcome data should evaluate the clinical relevance of subthreshold molecular alterations.

Organizing pneumonia is associated with molecular allograft injury and the development of antibody-mediated rejection.

BACKGROUND: The association between organizing pneumonia (OP) after lung transplantation with the development of acute rejection (AR) remains undefined. In addition, molecular allograft injury, as measured by donor-derived cell-free DNA (dd-cfDNA), during episodes of OP and its relationship to episodes of AR, chronic lung allograft dysfunction (CLAD), or death is unknown. METHODS: This multicenter, prospective cohort study collected serial plasma samples from 188 lung transplant recipients for dd-cfDNA at the time of bronchoscopy with biopsy. Multivariable Cox regression was used to analyze the association between OP with the development of AR (antibody-mediated rejection (AMR) and acute cellular rejection (ACR)), CLAD, and death. Multivariable models were performed to test the association of dd-cfDNA at OP with the risk of AR, CLAD, or death. RESULTS: In multivariable analysis, OP was associated with increased risk of AMR (hazard ratio (HR) = 2.26, 95% confidence interval (CI) 1.04-4.92, p = 0.040) but not ACR (HR = 1.29, 95% CI: 0.66-2.5, p = 0.45) or the composite outcome of CLAD or death (HR = 0.88, 95% CI, 0.47-1.65, p = 0.69). Median levels of dd-cfDNA were higher in OP compared to stable controls (1.33% vs 0.43%, p = 0.0006). Multivariable analysis demonstrated that levels of dd-cfDNA at diagnosis of OP were associated with increased risk of both AMR (HR = 1.29, 95% CI 1.03-1.62, p = 0.030) and death (HR = 1.16, 95% CI, 1.02-1.31, p = 0.026). CONCLUSIONS: OP is independently associated with an increased risk of AMR but not CLAD or death. The degree of molecular allograft injury at the diagnosis of OP may further predict the risk of AMR and death.

Identification of liver transplant biopsy phenotypes associated with distinct liver biological markers and allograft survival.

The intricate association between histologic lesions and circulating antihuman leucocyte antigen donor-specific antibodies (DSA) in liver transplantation (LT) requires further clarification. We conducted a probabilistic, unsupervised approach in a comprehensively well-annotated LT cohort to identify clinically relevant archetypes. We evaluated 490 pairs of LT biopsies with DSA testing from 325 recipients transplanted between 2010 and 2020 across 3 French centers and an external cohort of 202 biopsies from 128 recipients. Unsupervised archetypal analysis integrated all clinico-immuno-histologic parameters of each biopsy to identify biopsy archetypes. The median time after LT was 1.17 (interquartile range, 0.38-2.38) years. We identified 7 archetypes distinguished by clinico-immuno-histologic parameters: archetype #1: severe T cell-mediated rejection (15.9%); #2: chronic rejection with ductopenia (1.8%); #3: architectural and microvascular damages (3.5%); #4: (sub)normal (55.9%); #5: mild T cell-mediated rejection (4.9%); #6: acute antibody-mediated rejection (6.5%); and #7: chronic rejection with DSA (11.4%). Cell infiltrates vary in the archetype. These archetypes were associated with distinct liver biological markers and allograft outcomes. These findings remained consistent when stratified using the patient's age or indications for LT, with good performance in the external cohort (mean highest probability assignment = 0.58, standard deviation ± 0.17). In conclusion, we have identified clinically meaningful archetypes, providing valuable insights into the intricate DSA-histology association, which may help standardize liver allograft pathology classification.

Diarrhea after kidney transplantation: A study of risk factors and outcomes.

Background: Diarrhea in kidney transplant recipients (KTRs) can be associated with significant morbidity. Material and Methods: We evaluated 198 KTRs for a history of diarrhea post-kidney transplant at a tertiary care center in western India over 1 year. A protocol-based evaluation of diarrhea was done with respect to clinical features, diagnostic evaluation, associated acute allograft dysfunction, and its impact on long-term allograft function. Primary outcomes of interest were: chronic allograft injury (CAI) and the need for mycophenolate mofetil (MMF) withdrawal. We also assessed the effect of MMF withdrawal on the risk of the development of CAI. Results: Eighty-five of 198 (42.5%) recipients experienced diarrhea and a total of 140 diarrheal episodes were evaluated. The mean age of these 85 recipients was 38 ± 12 years and 72 (84.7%) were males. 73 of 85 recipients were on MMF at the time of diarrhea and in 35 (48%) of them MMF withdrawal was needed for chronic and persistent symptoms. Diarrhea was attributed to infective etiologies in 90 of 140 (64.2%) cases. Among the microbiologically confirmed infective diarrheal episodes, giardia and cryptosporidium were the common pathogens in 11/28 (39%) and 6/28 (21.4%) episodes respectively. One hundred and twenty-eight episodes out of 140 (91.4%) episodes were complicated by acute allograft dysfunction. Forty-one of 85 recipients (48.2%) developed chronic allograft injury and 12 (14.1%) developed allograft rejection (acute and/or chronic). Probability of chronic allograft injury was higher in those with MMF withdrawal. Conclusion: Diarrhea post-kidney transplant adversely affects graft function, especially after MMF withdrawal.

Local laboratory-run donor-derived cell-free DNA assay for rejection surveillance in heart transplantation-first six months of clinical experience.

INTRODUCTION: Donor-derived cell-free DNA (dd-cfDNA) is a blood biomarker detecting graft injury with high negative predictive value. While non-invasive strategies for heart transplant (HTx) rejection surveillance are widely adopted in the United States with centralized testing, data on the feasibility of dd-cfDNA assay at the local level are lacking. Here, we report the first 6 months of experience with a local laboratory-run dd-cfDNA assay in the routine clinical surveillance setting. METHODS: Twenty-six HTx patients with stable graft function were transitioned from endomyocardial biopsy-based (EMB) to dd-cfDNA-led rejection surveillance using a commercially available next-generation sequencing-based assay. RESULTS: In the 90 samples analyzed, dd-cfDNA fraction remained continuously low in most patients, thus 88% of surveillance EMBs could be safely avoided. In the case of ≥.25% dd-cfDNA, EMB was performed. There was no missed rejection. CONCLUSION: Our data show the feasibility to analyze dd-cfDNA at the local level and successful implementation of this non-invasive surveillance method into clinical practice, thus considerably reducing the frequency of invasive surveillance EMBs.

Pseudomonas-dominant microbiome elicits sustained IL-1ß upregulation in alveolar macrophages from lung transplant recipients.

BACKGROUND: Isolation of Pseudomonas aeruginosa (PsA) is associated with increased BAL (bronchoalveolar lavage) inflammation and lung allograft injury in lung transplant recipients (LTR). However, the effect of PsA on macrophage responses in this population is incompletely understood. We examined human alveolar macrophage (AMΦ) responses to PsA and Pseudomonas dominant microbiome in healthy LTR. METHODS: We stimulated THP-1 derived macrophages (THP-1MΦ) and human AMΦ from LTR with different bacteria and LTR BAL derived microbiome characterized as Pseudomonas-dominant. Macrophage responses were assessed by high dimensional flow cytometry, including their intracellular production of cytokines (TNF-α, IL-6, IL-8, IL-1ß, IL-10, IL-1RA, and TGF-ß). Pharmacological inhibitors were utilized to evaluate the role of the inflammasome in PsA-macrophage interaction. RESULTS: We observed upregulation of pro-inflammatory cytokines (TNF-α, IL-6, IL-8, IL-1ß) following stimulation by PsA compared to other bacteria (Staphylococcus aureus (S.Aur), Prevotella melaninogenica, Streptococcus pneumoniae) in both THP-1MΦ and LTR AMΦ, predominated by IL-1ß. IL-1ß production from THP-1MΦ was sustained after PsA stimulation for up to 96 hours and 48 hours in LTR AMΦ. Treatment with the inflammasome inhibitor BAY11-7082 abrogated THP-1MΦ IL-1ß production after PsA exposure. BAL Pseudomonas-dominant microbiota elicited an increased IL-1ß, similar to PsA, an effect abrogated by the addition of antibiotics. CONCLUSION: PsA and PsA-dominant lung microbiota induce sustained IL-1ß production in LTR AMΦ. Pharmacological targeting of the inflammasome reduces PsA-macrophage-IL-1ß responses, underscoring their use in lung transplant recipients.

Esophageal Dysfunction in Post-lung Transplant: An Enigma.

The prevalence of lung transplants has increased over the years, albeit with a low survival rate amongst all solid organ transplants, including liver and heart transplantation. Microaspiration is one of the primary mechanisms that has been implicated in the pathogenesis of lung injury following lung transplants. Of late, esophageal dysfunction such as gastroesophageal reflux and esophageal hypercontractility is often noted post-lung transplant. However, reflux is associated with chronic allograft lung injury such as bronchiolitis obliterans syndrome, which is one of the predictors for long-term survival in this specialized population. Its role in acute lung injury post-lung transplant is still being explored. This review critically examines the salient points which provide the current understanding of the characteristics, pathophysiology, and implications of esophageal dysfunction following lung transplant.

Extracellular vesicle-bound DNA in urine is indicative of kidney allograft injury.

Extracellular vesicle-bound DNA (evDNA) is an understudied extracellular vesicle (EV) cargo, particularly in cancer-unrelated research. Although evDNA has been detected in urine, little is known about its characteristics, localization, and biomarker potential for kidney pathologies. To address this, we enriched EVs from urine of well-characterized kidney transplant recipients undergoing allograft biopsy, characterized their evDNA and its association to allograft injury. The SEC-based method enriched pure EVs from urine of kidney transplant recipients, regardless of the allograft injury. Urinary evDNA represented up to 29.2 ± 8% (mean ± SD) of cell-free DNA (cfDNA) and correlated with cfDNA in several characteristics but was less fragmented (P < 0.001). Importantly, using DNase treatment and immunogold labelling TEM, we demonstrated that evDNA was bound to the surface of urinary EVs. Normalised evDNA yield (P = 0.042) and evDNA copy number (P = 0.027) significantly differed between patients with normal histology, rejection injury and non-rejection injury, the later groups having significantly larger uEVs (mean diameter, P = 0.045) and more DNA bound per uEV. ddDNA is detectable in uEV samples of kidney allograft recipients, but its quantity is highly variable. In a proof-of-principle study, several evDNA characteristics correlated with clinical and histological parameters (P = 0.040), supporting that the potential of evDNA as a biomarker for kidney allograft injury should be further investigated.

Pretransplant characteristics of kidney transplant recipients that predict posttransplant outcome.

Better characterization of the potential kidney transplant recipient using novel biomarkers, for example, pretransplant plasma endotrophin, will lead to improved outcome after transplantation. This mini-review will focus on current knowledge about pretransplant recipients' characteristics, biomarkers, and immunology. Clinical characteristics of recipients including age, obesity, blood pressure, comorbidities, and estimated survival scores have been introduced for prediction of recipient and allograft survival. The pretransplant immunologic risk assessment include histocompatibility leukocyte antigens (HLAs), anti-HLA donor-specific antibodies, HLA-DQ mismatch, and non-HLA antibodies. Recently, there has been the hope that pretransplant determination of markers can further improve the prediction of posttransplant complications, both short-term and long-term outcomes including rejections, allograft loss, and mortality. Higher pretransplant plasma endotrophin levels were independently associated with posttransplant acute allograft injury in three prospective European cohorts. Elevated numbers of non-synonymous single-nucleotide polymorphism mismatch have been associated with increased allograft loss in a multivariable analysis. It is concluded that there is a need for integration of clinical characteristics and novel molecular and immunological markers to improve future transplant medicine to reach better diagnostic decisions tailored to the individual patient.

Donor-derived cell-free DNA as a composite marker of acute lung allograft dysfunction in clinical care.

BACKGROUND: As a marker of underlying lung allograft injury, donor-derived cell-free DNA (dd-cfDNA) may be used to identify episodes of acute allograft injury in lung transplant recipients. We investigated the utility of dd-cfDNA to monitor subjects at risk of acute rejection or infection in routine clinical practice. METHODS: This multicenter, retrospective cohort study collected data from lung transplant recipients within 3 years of transplant at 4 centers between March 24, 2020 and September 1, 2020. During this period, as part of routine care during the COVID-19 pandemic, these centers implemented a home-based surveillance program using plasma dd-cfDNA in preference to surveillance bronchoscopy. Dd-cfDNA was used to detect acute lung allograft dysfunction (ALAD) - a composite endpoint of acute rejection and infection. dd-cfDNA levels in patients with ALAD were compared to stable patients. The performance characteristics of dd-cfDNA ≥ 1.0% to detect ALAD were estimated. RESULTS: A total of 175 patients underwent 380 dd-cfDNA measurements, of which 290 were for routine surveillance purposes. dd-cfDNA was higher in patients with ALAD than stable patients (Median (IQR) 1.7% (0.63, 3.1) vs 0.35% (0.22, 0.79), p < 0.001). As an indication of underlying ALAD during surveillance testing, the estimated sensitivity of dd-cfDNA ≥1% was 73.9%, specificity of 87.7%, positive predictive value of 43.4% and negative predictive value of 96.5%. CONCLUSIONS: dd-cfDNA identified acute lung allograft dysfunction in asymptomatic lung transplant patients that may not have been identified by using a clinically indicated biopsy strategy alone. dd-cfDNA <1.0% may be useful in ruling out acute rejection and infection, supporting its use as a potential noninvasive marker for surveillance monitoring.

Clinical outcomes from the Assessing Donor-derived cell-free DNA Monitoring Insights of kidney Allografts with Longitudinal surveillance (ADMIRAL) study.

The use of routine monitoring of donor-derived cell-free DNA (dd-cfDNA) after kidney transplant may allow clinicians to identify subclinical allograft injury and intervene prior to development of clinically evident graft injury. To evaluate this, data from 1092 kidney transplant recipients monitored for dd-cfDNA over a three-year period was analyzed to assess the association of dd-cfDNA with histologic evidence of allograft rejection. Elevation of dd-cfDNA (0.5% or more) was significantly correlated with clinical and subclinical allograft rejection. dd-cfDNA values of 0.5% or more were associated with a nearly three-fold increase in risk development of de novo donor-specific antibodies (hazard ratio 2.71) and were determined to be elevated a median of 91 days (interquartile range of 30-125 days) ahead of donor specific antibody identification. Persistently elevated dd-cfDNA (more than one result above the 0.5% threshold) predicted over a 25% decline in the estimated glomerular filtration rate over three years (hazard ratio 1.97). Therefore, routine monitoring of dd-cfDNA allowed early identification of clinically important graft injury. Biomarker monitoring complemented histology and traditional laboratory surveillance strategies as a prognostic marker and risk-stratification tool post-transplant. Thus, persistently low dd-cfDNA levels may accurately identify allograft quiescence or absence of injury, paving the way for personalization of immunosuppression trials.

Research progress and application of donor-derived cell-free DNA in diagnosis and treatment of kidney transplantation / 器官移植

Early diagnosis and treatment of rejection after kidney transplantation play a critical role in alleviating allograft injury. Detection of donor-derived cell-free DNA (dd-cfDNA) could be performed based on the next-generation sequencing and other techniques. The content of DNA fragments derived from necrotic and apoptotic donor kidney tissues in circulating body fluids could be determined by concentration and absolute quantitative methods, which has application potential in monitoring allograft injury in clinical practice. Compared with traditional serum creatinine and other indicators, dd-cfDNA detection may monitor allograft injury from several weeks to months in advance, providing a "time window" for clinical treatment and delaying graft failure. Along with deepening research of dd-cfDNA in recent years, dd-cfDNA has captivated widespread attention due to its non-invasiveness, high sensitivity and real-time evaluation of therapeutic effect. In this article, current study evidence and conclusions related to multidimensional application of dd-cfDNA detection in diagnosis and treatment of kidney transplantation were reviewed, and the future research and clinical application direction of dd-cfDNA were discussed, aiming to provide reference for widespread application of dd-cfDNA detection in clinical practice in China.

The Summarized Assessment of Endothelin A Receptor Expression in Renal Transplant Compartments Associated with Antibody-Mediated Rejection.

The occurrence of anti-endothelin A receptor antibodies may be useful in diagnosis of transplant damage. We noticed that the presence of the endothelin A receptor (ETA receptor) in biopsy compartments is yet to be defined. We decided therefore to analysed the presence and relevance of the ETA receptor in biopsy to define the cause. Our study aims to evaluate the expression of ETA receptors in renal recipients after a biopsy due to the worsening of transplant function. METHODS: The expression of ETA receptors was analyzed in renal transplant biopsies using the immunohistochemical method. The evaluation of ETA receptors was performed on paraffin sections. ETA receptor expression was analyzed in four compartments of renal transplant biopsies: glomeruli; vessels; tubular epithelium; and interstitium. The assessment was presented using a three-step scale (0: lack of expression; 1: mild to moderate immunoreactivity; 2: high expression). The results of each compartment from a single biopsy were summarized and assessed in the context of antibody-mediated rejection (AMR). RESULTS: We analyzed 156 patients who had a renal allograft biopsy after renal transplantation. For each patient, we created a summarized ETA receptor expression score. The summarized ETA receptor expression score analysis showed statistically significant differences in patients with and without AMR. In addition, we noticed that patients with AMR had a significantly higher mean summarized expression of ETA receptor score of 3.28 ± 1.56 compared to patients who had a biopsy for other reasons with a mean summarized ETA receptor expression score of 1.47 ± 1.35 (p < 0.000001). ROC analysis of the ETA receptor expression score for detecting AMR status showed that the most appropriate cut-off for the test of the chosen binary classifier is between 2 and 3 of the summarized ETA receptor expression score. CONCLUSIONS: The expression of endothelin A receptors in renal transplant compartments may be associated with antibody-mediated rejection. The positive ETA receptor staining might be a vital feature in the diagnosis of damage in AMR. The summarized ETA receptor expression score seems to be an exciting diagnostic tool in transplant injury assessment.

Quantitative contrast-enhanced ultrasound for the differentiation of kidney allografts with significant histopathological injury.

OBJECTIVE: To identify specific quantitative contrast-enhanced ultrasound (CEUS) parameters that could distinguish kidney transplants with significant histopathological injury. METHODS: Sixty-four patients were enrolled in this prospective observational study. Biopsies were performed following CEUS and blood examination. RESULTS: 28 biopsy specimens had minimal changes (MC group), while 36 had significant injury (SI group). Of these, 12 had rejection (RI group) and 24 non-rejection injury (NRI group). In RI and NRI groups, temporal difference in time to peak (TTP) between medulla and cortex (ΔTTPm-c) was significantly shorter compared to the MC group (5.77, 5.92, and 7.94 s, P = 0.048 and 0.026, respectively). Additionally, RI group had significantly shorter medullary TTP compared to the MC group (27.75 vs. 32.26 s; P = 0.03). In a subset of 41 patients with protocol biopsy at 1-year post-transplant, ΔTTPm-c was significantly shorter in the SI compared to the MC group (5.67 vs. 7.67 s; P = 0.024). Area under receiver operating characteristic curves (AUROCs) for ΔTTPm-c was 0.69 in all patients and 0.71 in patients with protocol biopsy. CONCLUSIONS: RI and NRI groups had shorter ΔTTPm-c compared to the MC group. AUROCs for both patient groups were good, making ΔTTPm-c a promising CEUS parameter for distinguishing patients with significant histopathological injury.

Transition of Renal Patients Using AlloSure Into Community Kidney Care (TRACK): Protocol for Long-Term Allograft Surveillance in Renal Transplant Recipients.

BACKGROUND: Patients with end-stage kidney disease require complex and expensive medical management. Kidney transplantation remains the treatment of choice for end-stage kidney disease and is considered superior to all other modalities of renal replacement therapy or dialysis. However, access to kidney transplant is limited by critical supply and demand, making it extremely important to ensure longevity of transplanted kidneys. This is prevented through lifelong immunosuppression, with caution not to overly suppress the immune system, resulting in toxicity and harm. Transition of care to community nephrologists after initial kidney transplantation and monitoring at a transplant center is an important process to ensure delivery of effective and patient-centric care closer to home. Once transplanted, laborious surveillance of the immune system and monitoring for potential rejection and injury are undertaken through an armamentarium of screening modalities. Posttransplant surveillance for kidney function and injury remains key to follow-up care. While kidney function, quantified by estimated glomerular filtration rate and serum creatinine, and kidney injury, measured by proteinuria and hematuria, are standard biomarkers used to monitor injury and rejection posttransplant, they have recently been demonstrated to be inferior in performance to that of AlloSure (CareDx Inc, Brisbane, CA) circulating donor-derived, cell-free DNA (dd-cfDNA). OBJECTIVE: The outcomes and methods of monitoring renal transplant recipients posttransplant have remained stagnant over the past 15 years. The aim of this study is to consider intensive surveillance using AlloSure dd-cfDNA in an actively managed protocol, assessing whether it increases long-term allograft survival in kidney transplant recipients compared with current standard clinical care in community nephrology. METHODS: The study protocol will acquire data from a phase IV observational trial to assess a cohort of renal transplant patients managed using AlloSure dd-cfDNA and patient care managers versus 1000 propensity-matched historic controls using United Network for Organ Sharing U.S. Scientific Registry of Transplant Recipients data. Data will be managed in a centralized electronic data server. The primary outcome will be superior allograft survival, as a composite of return to dialysis, retransplant, death due to allograft failure, and death with a functional graft (infection, malignancy, and cardiovascular death). The secondary endpoints will assess improved kidney function through decline in estimated glomerular filtration rate and immune activity through development of donor-specific antibodies. RESULTS: The total sample is anticipated to be 3500 (2500 patients managed with AlloSure dd-cfDNA and 1000 propensity-matched controls). Active enrollment began in November 2020. CONCLUSIONS: Based on a significant literature base, we believe implementing the surveillance of dd-cfDNA in the kidney transplant population will have a positive impact on graft survival. Through early identification of rejection and facilitating timely intervention, prolongation of allograft survival versus those not managed by dd-cfDNA surveillance protocol should be superior. INTERNATIONAL REGISTERED REPORT IDENTIFIER (IRRID): PRR1-10.2196/25941.

Endothelin A Receptors Expressed in Glomeruli of Renal Transplant Patients May Be Associated with Antibody-Mediated Rejection.

BACKGROUND: Non-human leukocyte antigen (HLA) anti-endothelin A receptor antibodies are presented as being potentially important, but the expression of the endothelin A receptor in glomeruli (ETA receptor (g+)) has not yet been described. We decided to evaluate the presence and relevance of the ETA receptor in for-cause renal transplant biopsies. The aim of our study was to evaluate the immunoreactivity of the ETA receptor and its significance in patients who underwent a renal transplant biopsy due to the deterioration of transplant function, with detailed characterization of staining in glomeruli. METHODS: The immunohistochemical expression of ETA receptor (ETAR) was analyzed in renal transplant biopsies. Microscopic evaluation was performed on paraffin sections in glomeruli. The analysis was performed using a two-step scale (0: lack of ETAR expression; 1: the presence of ETAR expression-mild to moderate immunoreactivity). RESULTS: We analyzed 149 patients who underwent renal allograft biopsy after renal transplantation. Positive staining of ETA receptors in glomeruli (ETA receptor (g+)) was noticed in 13/149 (8.7%) patients. Five of these 13 (38.5%) patients with ETA receptor (g+) developed antibody-mediated rejection (AMR), while 13 of the remaining 136 (9.5%) ETA receptor (g-) patients developed AMR (p = 0.0022). Graft loss was noticed in all but one ETA receptor (g+) patient with AMR (4/5; 80%), but only in 2/13 (15%) ETA receptor (g-) patients with AMR (p = 0.009) during the first year after biopsy. CONCLUSIONS: The expression of endothelin A receptors in glomeruli seems to be a potentially important feature in the diagnosis of damage during antibody-mediated rejection. It may help to identify patients at a higher risk of allograft rejection and injury.