Rejection Grade Research Articles

Artificial Intelligence-related Literature in Transplantation: A Practical Guide.

Artificial Intelligence-related Literature in Transplantation: A Practical Guide.

LPS-induced Airway-centered Inflammation Leading to BOS-like Airway Remodeling Distinct From RAS-like Fibrosis in Rat Lung Transplantation.

Localization of inflammatory stimuli may direct lung allografts to different phenotypes of chronic dysfunction, such as bronchiolitis obliterans syndrome (BOS) or restrictive allograft syndrome (RAS). We hypothesized that airway stimulation with lipopolysaccharide (LPS) in rats leads to airway-centered inflammation similar to human BOS. Rat left lung transplantation was conducted (donor: Brown Norway, recipient: Lewis). Allotransplant recipients received cyclosporine A (CsA) until postoperative day 56 with airway instillation of LPS (Allo-LPS, n = 8), phosphate buffered saline (Allo-PBS, n = 5) from days 35 to 46 (3 times a wk), or no further treatment (n = 4). Some allotransplant recipients received CsA until day 14 and were immunosuppression free after day 15 until day 56. Bronchial and pleural fibrosis were semiquantified; alveolar fibrosis was evaluated with a histological scale. The Allo-LPS group had significantly increased International Society for Heart and Lung Transplantation rejection grades (grade A, P = 0.005; grade B, P = 0.004), bronchial obstructive proportion (0.34 ± 0.04% [Allo-LPS] versus 0.11 ± 0.04% [Allo-PBS], P = 0.006), and airway resistance (3.05 ± 1.78 cm H2O·s/mL [Allo-LPS] versus 0.83 ± 0.58 cm H2O·s/mL [Allo-PBS], P = 0.007) compared with other groups. Allotransplant recipients that underwent a short course of CsA developed RAS-like fibrosis involving the airways, alveoli, and pleura. Airway instillation of LPS in allografts under immunosuppression resulted in BOS-like airway-centered inflammation and fibrosis distinct from RAS-like diffuse fibrosis, which was induced by a shortened course of immunosuppression. We propose novel animal models for BOS and RAS after lung transplantation.

Tissue Doppler velocities for ruling out rejection in heart transplant recipients in the context of myocardial strain imaging: a multivariate, prospective, single-center study.

To investigate the value of tissue Doppler velocities for ruling out treatment-requiring acute cellular rejection (TR-ACR), in the context of myocardial deformation analysis performed by means of speckle tracking echocardiography. We performed serial echocardiograms in 37 heart transplant recipients in their first year post-transplantation within 3h of the routine surveillance endomyocardial biopsies (EMB). The association of the sum of lateral mitral annulus systolic (s') and early diastolic (e') velocities, in absolute values, measured by tissue Doppler echocardiography (s'+ e'), with TR-ACR (ACR grade ≥ 2R) was investigated by multivariate analysis, including classic echocardiographic parameters and myocardial deformation variables. A total of 251 pairs of EMB and echo exams were performed, 35 (14%) with rejection grade ≥ 2R (TR-ACR). s'+ e' was independently associated to TR-ACR (OR 0.80, 95%CI 0.72-0.89, p < 0.0005), with a C statistic of 0.79 (95%CI 0.71-0.87, p < 0.0005) by ROC curve analysis. An s'+ e' value ≥ 23cm/s, present in 43% of studies, had a negative predictive value of 98% for ruling out TR-ACR. Moreover, in the same patients, s'+ e' significantly decreased when TR-ACR occurred after a study without this condition (- 3.7 ± 3.3cm/s, p = 0.003), but it was similar when rejection status was the same in the present versus the previous study. A drop in s'+ e' value < 2.7cm/s from the previous echocardiogram, had a 99% negative predictive value for ruling out TR-ACR. Tissue Doppler velocities, a widely available echo parameter, were found to be a valuable marker for ruling out TR-ACR in this multivariate study which included myocardial deformation variables.

Incidence of Acute Cellular Rejection in Heart Transplant Recipients from Hepatitis C Viremic Donors – One-Year Follow-Up

Passive transmission of hepatitis C (HCV) viremia from actively infected donors to uninfected recipients at the time of heart transplantation may modulate response to alloantigens and risk of allograft rejection. We evaluated the one-year incidence of acute cellular rejection (ACR) in patients transplanted from nucleic amplification testing positive (NAT+) HCV donors compared to those from NAT negative (NAT-) donors. Since January 2018, 25 patients completed one-year follow-up. All recipients underwent right ventricular endomyocardial biopsy (EMB) per our institution protocol. ACR was graded according to both the 1990 and the revised 2004 International Society for Heart and Lung Transplantation (ISHLT) criteria. All NAT+ donor recipients developed viremia detected by RT-PCR. Mixed models were used to assess the association between donor HCV NAT status, recipient viremia, tacrolimus levels and ACR in the first year post-transplant. Twelve NAT+ recipients (mean age 60, 67% male) and 13 NAT- recipients (mean age 54, 77% male) completed one-year follow-up; 182 and 191 EMB were performed, respectively. NAT+ recipients were associated with higher grade rejection compared with NAT- recipients (p=0.041). At least one episode of high grade rejection (2R/3A) occurred in 4 NAT+ recipients (33%) compared with 2 NAT- recipients (15%). At least one episode of low grade rejection (1R/1B or 1R/2) occurred in 11 NAT+ recipients (92%) compared with 7 NAT- recipients (54%). These findings were independent of the presence and magnitude of viremia and tacrolimus levels. No episodes of ACR 3R or antibody mediated rejection were detected during one-year follow-up in either group. There was no allograft dysfunction or mortality related to ACR in either group. One year data from our institution demonstrate increased ACR in heart transplant recipients from NAT+ donors. Most of the rejection episodes in the NAT+ group were low grade and did not translate into any adverse outcomes through one-year follow-up.

Lung Transplant Outcomes in Patients Hospitalized with Stable or Acute Exacerbations of Interstitial Lung Disease

Acute exacerbations of interstitial lung disease (AE-ILD) have a poor prognosis, and lung transplantation can be lifesaving. Previous studies have reported significantly higher mortality in patients transplanted with acute exacerbations of idiopathic pulmonary fibrosis (AE-IPF) compared to stable IPF. These results have yet to be corroborated, and whether they apply to the wide spectrum of AE-ILD beyond IPF is unknown. This study aimed to compare outcomes between transplanted AE-ILD patients, non-transplanted AE-ILD patients, and stable ILD patients hospitalized to undergo lung transplantation. This was a retrospective review of adults hospitalized with AE-ILD and stable patients hospitalized for elective lung transplantation due to end-stage ILD between January 2014 and February 2019. An acute exacerbation was defined using the revised definition and diagnostic criteria for AE-IPF. The primary outcome was post-hospitalization survival. For hospitalized transplanted patients, secondary outcomes included hospital length of stay post-transplant, grade of primary graft dysfunction, graft rejection, re-hospitalization, and cause of death. Twenty-nine patients were stable and electively admitted for lung transplantation, and 53 were hospitalized with AE-ILD, of whom 23 received a lung transplant and 28 did not. The average lung allocation score at the time of transplant for stable ILD patients was 41.79 compared to 81.61 for patients with AE-ILD (p<0.0001). Average follow-up was 17±10 months. Every lung transplant recipient survived, whereas only 8 of 28 (28%) non-transplanted patients with ILD exacerbations survived to hospital discharge. Secondary outcomes were not statistically significantly different between AE-ILD and stable ILD lung transplant recipients. Mortality rates were significantly higher in patients with AE-ILD who were not transplanted, but survival and post-hospitalization outcomes were comparable in patients transplanted with AE-ILD versus stable ILD. These results highlight the important role played by lung transplantation in eligible patients admitted with AE-ILD.

Evaluation of Induction Strategies in Heart Transplant at a Single Center

Immunosuppression induction is commonly utilized in heart transplant (HT) to prevent acute rejection and/or delay calcineurin inhibitor (CNI) initiation. However, guidance on whether to use induction and preferred agent(s) are not well defined. This is reflected by high practice variability across centers. According to ISHLT registry data, 54% of adult HT cases utilized induction, 31% with an IL-2R antagonist and 23% with a T-cell depleting agent. Our center has primarily utilized 3 strategies based on rejection risk and need to delay CNI: IL-2R antagonist (basiliximab), T-cell depleting (anti-thymocyte globulin, rabbit (rATG)), or no induction. Our study's objective was to compare these strategies' safety and effectiveness. A retrospective chart review was conducted at a large academic medical center, including HT cases performed between January 2015 and April 2019. Patients were stratified by induction strategy used at the time of transplant. The primary outcomes were rate of biopsy-proven acute cellular rejection (ACR) grade 2R or higher, treated antibody mediated rejection (AMR), and any infection within one year of transplantation. From January 2015 to April 2019, 145 total HTs were included in our study (123 heart, 20 heart-kidney, and 2 heart-liver). rATG was the most common induction strategy used (36%), followed by no induction (35%), and basiliximab (26%). Four patients (3%) received 1 dose of basiliximab but were switched to rATG. ACR rates were not statistically different among induction groups: 22% with no induction, 11% with basiliximab, 17% with rATG, and 0% with combination (p = 0.51). AMR rates were also not statistically different: 6% with no induction, 5% with basiliximab, 4% with rATG, and 0% with combination (p = 0.93). There was no difference detected in donor-specific antibody (DSA) formation at 1 year (p = 0.81). The percentages of patients with any infection were: 53% with no induction, 55% with basiliximab, 62% with rATG, and 75% with combination (p = 0.90). Incidences of ACR, AMR, DSA formation, and infection were not statistically different among induction strategies at one year post-transplant. It may be beneficial to individualize induction strategies based on recipient factors at the time of transplantation. Long term outcomes in this patient cohort are yet to be determined.

The Use of Artificial Intelligence (AI) Machine Learning to Determine Myocyte Damage in Cardiac Transplant Acute Cellular Rejection

Cardiac transplant patients must be on lifelong surveillance for the occurrence of acute cellular rejection (ACR). Despite potent immunosuppressants, ACR occurs when recipient T cells recognize donor antigens to cause cardiac myocyte destruction. Identifying myocyte damage is critical for determining the grade of rejection, and thus greatly impacts treatment decisions. The aim of this study is to determine if a machine learning algorithm can reach acceptable performance of identifying myocyte damage representative of ACR from benign conditions. AI technology has recently been under robust investigation in cancer pathology but is in its infancy in transplant pathology. This is the first AI algorithm to our knowledge, to identify myocyte damage in cardiac transplant patients. All regions of myocyte damage were annotated by a board-certified cardiac pathologist at a high-volume cardiac transplant center. Cases diagnosed as antibody-mediated rejection (AMR) were excluded. Annotations were extracted using the Openslide software and fed into a convolutional neural network which used the locked VGG16 base for transfer learning. Keras was used for AI modeling and training. Four annotation classes were included in the algorithm (normal, healing injury, Grade 1R1A and Grade 1R2). A total of 19,617 annotations (10,855 regions of ACR, 5002 healing injury, 3760 normal) were completed from 200 hematoxylin and eosin slides scanned using a Leica Aperio AT2 digital whole slide scanner at 40X magnification. The AI algorithm successfully distinguished myocyte damage (Grade 1R2) from non-myocyte damage (Grade 1R1A) with 94% validation accuracy. ACR was distinguished from healing injury with 98-99% validation accuracy, and from normal cardiac myocytes with 99% validation accuracy. This study provides evidence for the first time, that a machine learning algorithm can be taught and validated to distinguish myocyte damage ACR from non-myocyte damage ACR. To our knowledge, this is one of the first AI tools developed in cardiac transplant pathology that may be used as an adjunct tool to decrease inter-observer diagnostic variability and reduce diagnostic error amongst pathologists.

Combined AlloSure and AlloMap Testing in Multi-Organ Heart Transplantation Rejection Surveillance

AlloSure test is a non-invasive blood test designed to detect the presence of donor cell-free DNA in the recipients blood as a measure of the probability of rejection in heart transplant recipients. The result is displayed as a percent of donor-derived cell-free DNA (dd-cfDNA) in the totalcell-free DNA (cfDNA). Recommended threshold of 0.2% dd-cfDNA has been predictive of low likelihood of rejection. There is no data looking at its value and validation in multi-organ transplant. We aimed to study this area by reviewing our transplant database. All patients who received more than one solid organ transplant at our center and had AlloSure testing were included. Study outcomes included one year survival, rejection grade 2R or more, and hemodynamically significant graft dysfunction. There were (7) patients included in the study, average AlloSure score was 0.93% ±0.61% with an average AlloMap score of 33.8±2.14. Four patients (57.1%) had heart and kidney transplant, 3 patients (42.9%) had heart and liver transplantation. Average AlloSure score for heart/kidney transplant recipients was 0.52±0.17% with an average AlloMap score of 33.6±2.28. The while average AlloSure score for heart/liver transplant recipients was 1.21±0.55% mean AlloMap score of 33.93±2.32. None of our patients had graft dysfunction or biopsy-proven rejection >=2R. Survival rate was 100% for the first year in our patients CONCLUSION: AlloSure levels were higher in heart-liver vs. heart-kidney recipients, and in both cohorts higher than the 0.2% threshold recommended for heart transplant prediction of rejection, however did not predict rejection. In our cohort, while AlloMap scores were consistent in both groups, (33.93±2.32 vs. 33.6±2.28 respectively). Elevated AlloSure was not predictive of rejection in multiorgan heart transplant recipients.

Development of a Pre-Implantation Regulatory T Cell-Permissive Immunosuppression Protocol in a Rat Model of Ex Vivo Lung Perfusion Followed by Lung Transplantation

CD4+CD25highFoxp3+ regulatory T cells (Treg) can establish immunologic tolerance in animal models. We have developed a method to deliver recipient-derived Tregs to donor lungs during ex-vivo lung perfusion (EVLP). Our goal is to maximize the effectiveness of this therapy by developing a Treg-permissive post transplant immunosuppression protocol. We hypothesized that combination therapy with interleukin-2 (IL-2)/anti-IL-2 antibody complexes (IL-2c) and tacrolimus (Tac) would facilitate the expansion of endogenous Tregs and attenuate acute rejection, thus creating an environment permissive to Treg therapy. We performed rat left lung transplantation (LTx) experiments using Fischer 344 (F344, RT-1lv1) donors and Wistar Kyoto (WKy, RT-1l) recipients with or without antecedent 3h EVLP. Animals received: no treatment (NT); IL-2c (a single low [30ug] or high [60ug] dose) alone; Tac (0.1mg/kg/day, 7 doses) alone; or both IL-2c and Tac, intraperitoneally starting on the day of transplantation. Allografts that underwent EVLP had lower acute rejection grades in IL-2c/Tac-treated rats than in NT and Tac-treated rats (A Grade p = 0.046; B Grade p = 0.064; Fig1). In contrast, there were no differences among these groups in allografts that had not undergone EVLP. In the grafts, the frequency of CD4+CD25highFoxp3+ cells increased in both low and high dose IL-2c/Tac groups compared with Tac group, regardless of EVLP (p = 0.012, p = 0.107; Fig 2). Although the frequency of CD4+CD25+Foxp3- effector T cells also increased with high dose IL-2c in the non-EVLP group, this was not seen with EVLP (p = 0.804) (Fig 2). Despite the presence of Tac, IL-2c increased Tregs in the graft after transplantation and attenuated acute rejection in EVLP-treated lungs. This work lays the groundwork for pre-implantation allograft-directed regulatory T cell therapy.

Three-Dimensional Speckle Tracking Echocardiography for Assessment of Left Ventricular Function and Myocardial Mechanics after Pediatric Heart Transplantation

Three-dimensional (3D) echocardiography for the assessment of LV size, function and myocardial mechanics has been commonly used after heart transplantation (HT) in adults, but not yet in children. We purposed to explore the feasibility of 3D echocardiography for these parameters in children after HT. We analyzed data from 33 pediatric HT recipients with median age 10 yrs at HT (3 mos -17yrs) who had ≥ 2 echocardiograms with 3D LV full volume image within 24 hours of routine biopsy at BCH between March 2013 and December 2015. Rejection was defined by biopsy as acute cellular rejection Grade ≥2R or antibody mediated rejection (ISHLT-2004). We analyzed 3D LV volumes, ejection fraction (EF), mass and mass/volume, global longitudinal, circumferential and radial strains (GLS, GCS and GRS), twist and torsion at first, 6 and 12 months after HT; and compared with corresponding values in 30 age- and BSA-matched controls with median age 7.2 yrs (2 mos-17yrs). During the initial 30 days post HT, all HT recipients had smaller end-diastolic volumes than controls (median EDV: 38 vs. 47 ml/m2) resulting in mild LV hypertrophy (Mass: 50 vs. 43 gr/m2) and impairment in LV systolic function (EF: 56 vs. 65%, GLS: 21 vs. 26%, GCS: 26 vs. 33%, GRS: 39 vs. 48%, for all P<0.001). Among 23 rejection free recipients, EDV, ESV, Mass and GRS gradually increased within 1 year after HT (ANOVA P=0.015, P=0.022, P=0.015, P<0,001, respectively), while stroke volume, EF, GLS and GCS increased within 6 months (for all P≤0.008) and remained steady state through 1 year after HT. The initial mild LV hypertrophy decreased by 6 months after HT (mass/volume: P =0.028) without further changes until 1 year after HT CONCLUSION: 3D echocardiography can assess LV size, function and myocardial mechanics and reflects LV post-transplant recovery in rejection-free pediatric recipients. There were changes in LV size, function and myocardial mechanics associated with rejection and deserve further assessment in larger pediatric heart recipient cohorts.

Mucosa and Rejection in Facial Vascularized Composite Allotransplantation: A Systematic Review.

Facial vascularized composite allotransplantation (fVCA) presents an established approach to restore form and function of patients with catastrophic facial defects. Skin is one of the target tissues of the rejection process, and due to its easy accessibility has become the gold standard in the diagnosis of rejection. Mucosal rejection frequently occurs; however, the added value of mucosal rejection assessment for patient management is unknown. We conducted a systematic review of manuscripts listed in the MEDLINE/PubMed and GoogleScholar databases to identify articles that provide data on mucosal rejection following fVCA. For inclusion, papers had to be available as full-text and written in English. Non-VCA studies and animal studies were excluded. We followed the Preferred Reporting Items for Systematic Reviews and Meta-Analyses guidelines. We included 17 articles that described changes in allotransplanted mucosa of fVCAs. These articles yielded data on 168 BANFF graded biopsies of corresponding skin and mucosa biopsies. Rejection grades were consistently higher in mucosal biopsies. Concordance between allograft skin and mucosa biopsy grades increased with an increasing skin-BANFF grade. Mucosa rejection grades were on average lower in the early stages of the posttransplant period (<postoperative mo 12, time of motor, and sensory recovery) when compared to the later stages (>postoperative mo 12). The mucosa of facial allotransplants is one of the primary targets of rejection. The data indicates that higher-grade skin rejection does not occur in absence of mucosal rejection. Further investigations are needed to elucidate the exact role of mucosal biopsies for fVCA patient management.

Robustness Testing of Mesenchymal Stem Cell Monotherapy Following Vascularized Composite Allotransplantation.

Immunosuppression risks are a major concern with vascularized composite allotransplantation (VCA). As an emerging strategy, the antirejection role played by mesenchymal stem cells (MSCs) is receiving attention. However, the current literature reports are inconclusive regarding the robustness of the MSC monotherapy. Using a rat forelimb VCA model, this study tested the robustness of the immunomodulation efficacy of gingival-derived MSCs (GMSCs) and bone marrow-derived MSCs (BMMSCs). Forelimbs were transplanted on pairs of major histocompatibility complex-incompatible rats (Wistar-Kyoto donor, Lewis [LEW] recipient). Twenty-four LEW rats were randomly divided into four groups, including control (no treatment) and three treatment groups: rapamycin (2 mg/kg/day for 28 days, postoperatively), BMMSC and GMSC, both of which received donor-derived stem cells administered intravenously on postoperative days (PODs) 0, 3, 7, and 14. Rejection was considered as 80% skin necrosis of the allograft. Microcomputed tomography (µCT) was performed to evaluate healing at osteosynthesis site. On POD 14, limbs from each group underwent histological analysis and rejection grading using the Banff system. Both BMMSC (15.0 days) and GMSC (14.7 days) treatment failed to prolong VCA survival in comparison with the control group (13.8 days; p > 0.050), while the rapamycin significantly delayed acute VCA rejection (24.5 days; p = 0.003). Micro-CT imaging revealed no gross visual difference across all groups. Histology revealed that the control group was most severely affected (grades III and IV) followed by MSC (grade II) and rapamycin (grade I). MSC monotherapy, both BMMSC and GMSC, did not inhibit rejection in our VCA model. Skin immunogenicity is an important issue in promoting rejection, and a concomitant immunosuppression regimen should be considered to prolong allograft survival.

P937 Left atrial longitudinal strain as a marker of acute cellular rejection in heart transplant recipients: impact of intervendor variability

Abstract Introduction and purpose Preliminary reports suggests that left atrial longitudinal strain (LALS) variables are a sensitive marker of acute cellular rejection (ACR) in heart transplant recipients (HTxR), discriminating between those studies without rejection and those with any grade of rejection. Intervendor variability is a concern in the widespread use of this technique. Our objective was to compare the LALS evaluated by two different softwares. Methods From September 2014 to October 2016 we performed, in 18 consecutive adult HTxR in their first year posttransplantation, serial echocardiographic exams within 3 hours of the routine surveillance endomyocardial biopsies (EMB), in a single centre. Peak average longitudinal strain, and strain rate were measured in the left atrium in the apical four chambers view in all studies, using both softwares, its association with the presence of ACR was investigated, and intervendor variability was evaluated. Results a total of 147 pairs of EMB and echo exams were performed, 65 with no rejection (grade 0R), 82 with any grade of ejection (grades 1R and 2R). Intraclass correlation coeficients for intervendor reproducibility for LALS and LALSR were 0.4 (95%CI 0.26 - 0.57) and 0.3 (95%CI -0.06 - 0.52) respectively. The number of segments evaluable by each software was significantly different. Association of LALS with rejection is shown in the table. Conclusions In this monocentric prospective study, left atrial longitudinal strain variables were found to be a sensitive marker of acute cellular rejection in heart transplant recipients. Although intervendor reproducibility was poor, these results were consistent between both software. Results Software n/N (%)* Variable No ACR ACR≥1 p value Siemens 114/147 (77.5) Peak atrial LS 19.4 ± 7.4 15.5 ± 6.3 0.006 114/147 (77.5) Peak atrial LSR 1.5 ± 0.4 1.3 ± 0.5 0.005 TomTec 131/147 (89.1) Peak atrial LS 19.1 ± 6.2 14.1 ± 5.4 &amp;lt;0.005 131/147 (89.1) Peal atrial LSR 1.0 ± 0.4 0.8 ± 0.3 &amp;lt;0.005 n: number of exams evaluable by each software. N: total numbers of exams. *p = 0.01 for comparison between the proportion of exams evaluable by each software.

Pancreas allograft biopsies procedure in the management of pancreas transplant recipients.

Pancreas transplantation is an effective therapy for diabetic patients, which can significantly improve the survival rate and quality of life of diabetic patients. According to the international registration of pancreas transplantation center, the global total pancreas transplantation has reached more than 80,000 cases by 2017, including pure pancreas transplantation and simultaneous pancreas-kidney transplantation (SPK). With the development and application of a new type of immunosuppressant, with the gradual maturity of organ preservation technology and surgical technology, the pancreas transplantation has rapidly on a global scale. However, pancreas transplantation still has more problems than limit its development compared with other organ transplantation. For example, the early diagnosis and treatment of pancreatic rejection are of considerable significance to the prognosis of pancreas transplantation. Some surveillance methods of diagnosis have been used increasingly, among which the histopathological diagnosis is particularly important. The first Banff schema for the histological diagnosis of pancreas rejection has been published, which primarily dealt with the diagnosis of acute T-cell-mediated rejection (ACMR). In recent years, antibody-mediated rejection (AMR) has been more emphasized as the primary cause of graft failure. The Banff pancreas allograft rejection grading schema was updated in 2011 by a broad-based multidisciplinary panel, presenting comprehensive guidelines for the diagnosis of AMR.

Plasma CD5L and non-invasive diagnosis of acute heart rejection

Acute rejection is one of the most important direct contributors to mortality after heart transplantation. Advances in the development of novel non-invasive approaches for the early identification of allograft rejection are necessary. We conducted a non-targeted proteome characterization focused on identifying multiple plasmatic protein differences to evaluate their diagnostic accuracy for rejection episodes. We included consecutive plasma samples from transplant recipients undergoing routine endomyocardial biopsies. A liquid chromatography-tandem mass spectrometry analysis using isobaric tags (tandem mass tag 10-plex) was performed and concentrations of CD5L were validated using a specific sandwich enzyme-linked immunosorbent assay. A total of 17 altered proteins were identified as potential markers for detecting heart transplant rejection, most involved in inflammation and immunity. CD5L, an apoptosis inhibitor expressed by macrophages, showed the best results in the proteomic analysis (n = 30). We confirm this finding in a larger patient cohort (n = 218), obtaining a great diagnostic capacity for clinically relevant rejection (≥Grade 2R: area under the curve = 0.892, p < 0.0001) and preserving the accuracy at mild rejection (Grade 1R: area under the curve = 0.774, p < 0.0001). CD5L was a strong independent predictor, with an odds ratio of 14.74 (p < 0.0001), for the presence of rejection. Episodes of acute cardiac allograft rejection are related to significant changes in a key inhibitor of apoptosis in macrophages, CD5L. Because of its precision to detect acute cellular rejection, even at mild grade, we propose CD5L as a potential candidate to be included in the studies of molecule combination panel assays. This finding could contribute to improving the diagnostic and preventive methods for the surveillance of cardiac transplanted patients.

P761The effect of extracorporeal photopheresis on cardiac allograft rejection and on lymphocyte subclasses

Abstract Background Cardiac allograft rejection is known to have a profound impact on graft survival and mortality after heart transplant. Previous data on the efficacy of extracorporeal photopheresis (ECP) in the management of cardiac allograft rejection is encouraging. Though, clear evidence on the exact indication and data regarding its effect on distinct lymphocyte subtypes are still lacking. Based on their cytokine production, both helper and cytotoxic T cells can differentiate into either regulatory cells participating in the suppression of rejection or into effector cells responsible for its maintenance. Regulatory T cells are essential for the termination of rejection, while B lymphocytes and natural killer (NK) cells contribute to it. Purpose We aimed to investigate the anti-rejection efficacy and the impact of ECP on peripheral blood lymphocyte subclasses in adult heart transplant recipients. Methods In a retrospective analysis of 12 consecutive patients treated with ECP for cardiac allograft rejection between 2013 and 2019, we examined the grade of rejection in endomyocardial biopsies (EMB) based on the International Society for Heart and Lung Transplantation classification. We analysed the absolute counts and the percentages of helper, cytotoxic and regulatory T cells, B lymphocytes and NK cells with fluorescence activated cell sorting. Measurements were performed both before and after the ECP treatment period. Data values were given as either mean±standard deviation or median [min–max]. Results The patients underwent 26 [2–39] ECP treatments in addition to standard immunosuppressant therapy. Whereas grade 2R cellular rejection was detected in 83% of the cases prior to initiating ECP, none of the examined EMB specimen revealed rejection greater than grade 1R cellular rejection post ECP therapy. The average grade of cellular rejection improved significantly (1.25±0.45 vs. 0.50±0.53; p=0.022). The absolute count and the percentage of helper T cells increased significantly post ECP therapy (0.34 G/l±0.26 G/l vs. 0.51 G/l±0.39 G/l; p=0.018 and 3.43%±2.24% vs. 5.98%±3.64%; p=0.017, respectively). There was also a significant rise in the percentage of cytotoxic T cells (2.33%±1.46% vs. 4.16±2.98%; p=0.027). We noticed an almost significant twofold increase in the percentage of regulatory T cells on completion of the ECP therapy (0.20%±0.22% vs. 0.37%±0.20%; p=0.060). Neither B lymphocyte nor NK cell counts revealed any significant changes. Conclusion ECP was effective in reducing the severity of cardiac allograft rejection episodes. The significant decrease in rejection rates might be indicative of the predominance of anti-inflammatory helper and cytotoxic T cell subpopulations and the increase of regulatory T cell count post ECP therapy. However, discussion of the results are limited by small sample size and the effect of medical therapy on the lymphocytes.

How Should Pancreas Transplant Rejection Be Treated?

Limited published data exist to guide the treatment of pancreas transplant rejection. We reviewed the treatment and outcomes of 158 first episodes of biopsy-proven pancreas rejection between 1 January 1997 and 31 December 2016. Within each Banff grade of rejection, we compared response rates and long-term outcomes with steroids alone versus steroids plus antithymocyte globulin (ATG). Of 158 pancreas recipients with rejection, 65 were treated with steroids alone. Eighty-three percent of patients with grade I, 60% with grade II, and 33.33% with grade III rejection responded to treatment with steroids alone. Ninety-three patients were treated with steroids plus ATG. The response rates were 69% in grade I, 76% in grade II, and 73% in grade III. Response rates and graft survival were not different with grade I rejection treated with steroids alone versus steroids plus ATG. However, response rates and graft survival were significantly better with grade III rejection treated with the addition of ATG, and graft survival rates were significantly better with grade II rejection treated with the addition of ATG. Grade I pancreas rejection can usually be successfully treated with steroids alone, whereas grade II and III rejection should usually be treated with steroids plus ATG, as the addition of ATG improves both response rates and graft survival.

Ultrasound Molecular Imaging of Lymphocyte-endothelium Adhesion Cascade in Acute Cellular Rejection of Cardiac Allografts.

Acute cellular rejection is one of the main reasons for graft failure after heart transplantation. A precise diagnosis at the early stage of acute cellular rejection is a big challenge for clinicians. Given the importance of the interaction between T cells and graft endothelia in initiating rejection, we developed T cell-microbubble complexes (cell-MBs) as ultrasound molecular imaging probes to monitor the lymphocyte-endothelium adhesion cascade in cardiac acute cellular rejection. Cell-MBs were fabricated by incubating lymphocytes with anti-CD4 antibody-conjugated MBs (MBCD4). The potential of cell-MBs as probes for detecting acute cardiac rejection was examined. Donor hearts from Brown Norway or Lewis rats were transplanted into Lewis recipients. Ultrasound molecular imaging was performed on allografts of untreated or cyclosporin A (CsA)-treated recipients, and isografts on posttransplantation day 3. Histology was used to assess rejection grades. We detected a significantly stronger ultrasound molecular imaging signal of cell-MBs than that of MBCD4 or plain MBs in allografts of untreated and CsA-treated recipients. No signal enhancement was observed in isografts with cell-MBs. The signal of cell-MBs in allografts of the untreated group was significantly higher than that in the CsA-treated group, and the signal in the CsA-treated group was higher than that in isografts. Histology confirmed grade 3R rejection in the untreated group, grade 2R rejection in CsA-treated group, and no rejection in isografts. Our study suggests that cell-MBs can function as a promising probe to image the dynamic lymphocyte-endothelium adhesion cascade for noninvasive diagnosis of cardiac acute cellular rejection.

Prolonged warm ischemia exacerbated acute rejection after lung transplantation from donation after cardiac death in a mouse.

In lung transplantation (LTx) from donation after cardiac death (DCD), the donor lungs are inevitably exposed to warm ischemic time (WIT) between the cardiac arrest and the initiation of cold preservation. We conducted this study to examine the effect of prolonged WIT on lung allograft rejection in a murine model of LTx from DCD. Allogeneic BALB/c → B6 LTx from DCD was performed with a WIT of 15min (WIT15 group, n = 5) or 60min (WIT60 group, n = 5). Recipients were immunosuppressed by perioperative costimulatory blockade. The lung allografts were analyzed by histology and flow cytometry on day 7 after the LTx. Histologically, the rejection grade in the WIT60 group was significantly higher than that in the WIT15 group (3.4 ± 0.4 vs. 2.2 ± 0.2, P = 0.0278). Moreover, the intragraft CD8+ to CD4+ T cell ratio in the WIT60 group was significantly higher than that in the WIT15 group (2.3 ± 0.12 vs. 1.2 ± 0.11, P < 0.0001). Prolonged WIT could exacerbate the severity of lung allograft rejection after LTx from DCD. Minimization of the WIT could improve the outcomes after LTx from DCD.

P2.37: Variance in peripheral blood absolute lymphocyte counts as a predictor of exfoliative rejection in small bowel transplant recipients

Introduction: Exfoliative rejection (ER) following small bowel or combined liver/small bowel transplantation is an extreme form of graft rejection associated with significant morbidity and mortality with high rates of allograft removal. Re-transplantation after exfoliative rejection has demonstrated low success rates. During the outset of rejection episodes, few predictors differentiate between ER and non-exfoliative rejection. Aggressive immunosuppression with antibody based therapy and early surgical intervention remain the cornerstone of management. Our treatment protocol for acute cellular rejection requires failure of a steroid burst before antithymocyte antibodies are started, but excessive delay in initiation of antibody therapy may result in exfoliation and graft loss. Our objective is to determine if peripheral blood lymphocyte counts can predict progression to ER. Methods: All patients undergoing a small bowel or combined liver/small bowel transplant at Cincinnati Children’s Hospital Medical Center (CCHMC) were retrospectively reviewed for this study. All with biopsy proven acute cellular rejection and peripheral blood lymphocyte enumeration were included. The histologic severity of the rejection episode and lymphocyte counts prior to and during the rejection episode were collected. Results: Electronic medical record changes permitted review of 38 of 55 transplants since 2003. Twenty-nine patients (76%) had histologic rejection greater than Grade 1. Of all patients, 5 (13%) had ER. Early biopsies eventually progressing to ER had higher peripheral blood absolute lymphocyte counts (ALC) prior to rejection than did biopsies diagnostic of rejection failing to progress (960 vs 600, p = 0.02). More importantly, peripheral blood lymphocyte counts also rose much more dramatically in those whose biopsies subsequently progressed to exfoliation than in those whose rejection did not progress (1179% vs 81%, p <0.001). Conclusion: Based on these data, absolute lymphocyte count, specifically, the variance in ALC is associated with progression from low grade rejection to ER. Although, there was a statistically significant difference in the ALC in patients with exfoliation, substantial variance from baseline may be more important than the absolute number in predicting ER, thereby justifying early use of antithymocyte globulin or alemtuzumab.