Allograft Injury Research Articles

Cardiac Allograft Injuries: A Review of Approaches to a Common Dilemma, With Emphasis on Emerging Techniques.

Clinical features of allograft injury are often unreliable, and context within the transplant journey is key. In the setting of post-transplant allograft dysfunction, the choice of initial investigation depends on clinical assessment and history. One of the major considerations is the time post transplantation in helping to decide a likely cause for allograft injury. Immediately post transplantation, it is important to consider donor factors (including donor demographics as well as immunological match), ischaemic times, surgical issues as well as early rejection. Clinical suspicion needs to remain high with variable presentations, including haemodynamic instability, arrhythmia, as well as left ventricular dysfunction. Symptoms of allograft dysfunction may include dyspnoea, exertional intolerance, dizziness / lightheadedness, palpitations, as well as right or left heart failure. In the coming weeks and months, endomyocardial biopsy and blood-based biomarkers may be helpful including high sensitivity troponin and donor-derived cell-free DNA. Molecular markers for rejection are hopeful, and may also be useful in non-ischaemic causes of allograft dysfunction. Screening remains important late post heart transplant due to variety of signs associated with rejection (early) and lack of typical anginal symptoms (later). New imaging modalities - especially cardiac magnetic resonance imaging, have been shown to be useful for assessing cause of allograft dysfunction including ischemia, infarction and rejection.

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

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. 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. 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%. 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.

Complement Blockade in Recipients Prevents Delayed Graft Function and Delays Antibody-mediated Rejection in a Nonhuman Primate Model of Kidney Transplantation.

Complement activation in kidney transplantation is implicated in the pathogenesis of delayed graft function (DGF). This study evaluated the therapeutic efficacy of high-dose recombinant human C1 esterase inhibitor (rhC1INH) to prevent DGF in a nonhuman primate model of kidney transplantation after brain death and prolonged cold ischemia. Brain death donors underwent 20 h of conventional management. Procured kidneys were stored on ice for 44-48 h, then transplanted into ABO-compatible major histocompatibility complex-mismatched recipients. Recipients were treated with vehicle (n = 5) or rhC1INH 500 U/kg plus heparin 40 U/kg (n = 8) before reperfusion, 12 h, and 24 h posttransplant. Recipients were followed up for 120 d. Of vehicle-treated recipients, 80% (4 of 5) developed DGF versus 12.5% (1 of 8) rhC1INH-treated recipients (P = 0.015). rhC1INH-treated recipients had faster creatinine recovery, superior urinary output, and reduced urinary neutrophil gelatinase-associated lipocalin and tissue inhibitor of metalloproteinases 2-insulin-like growth factor-binding protein 7 throughout the first week, indicating reduced allograft injury. Treated recipients presented lower postreperfusion plasma interleukin (IL)-6, IL-8, tumor necrosis factor-alpha, and IL-18, lower day 4 monocyte chemoattractant protein 1, and trended toward lower C5. Treated recipients exhibited less C3b/C5b-9 deposition on day 7 biopsies. rhC1INH-treated animals also trended toward prolonged mediated rejection-free survival. Our results recommend high-dose C1INH complement blockade in transplant recipients as an effective strategy to reduce kidney injury and inflammation, prevent DGF, delay antibody-mediated rejection development, and improve transplant outcomes.

Clinical Validation of an Immune Quiescence Gene Expression Signature in Kidney Transplantation.

Despite advances in immune suppression, kidney allograft rejection and other injuries remain a significant clinical concern, particularly with regards to long-term allograft survival. Evaluation of immune activity can provide information about rejection status and help guide interventions to extend allograft life. Here, we describe the validation of a blood gene expression classifier developed to differentiate immune quiescence from both T cell-mediated rejection (TCMR) and antibody-mediated rejection (ABMR). A five-gene classifier (DCAF12, MARCH8, FLT3, IL1R2, and PDCD1) was developed on 56 peripheral blood samples and validated on two sample sets independent of the training cohort. The primary validation set comprised 98 quiescence samples and 18 rejection samples: seven TCMR, ten ABMR, and one mixed rejection. The second validation set included eight quiescence and 11 rejection samples: seven TCMR, two ABMR, and two mixed rejection. AlloSure donor-derived cell-free DNA (dd-cfDNA) was also evaluated. AlloMap Kidney classifier scores in the primary validation set differed significantly between quiescence (median, 9.49; IQR, 7.68-11.53) and rejection (median, 13.09; IQR, 11.25-15.28), with P<0.001. In the second validation set, the cohorts were statistically different (P=0.03) and the medians were similar to the primary validation set. The AUC for discriminating rejection from quiescence was 0.786 for the primary validation and 0.800 for the second validation. AlloMap Kidney results were not significantly correlated with AlloSure, although both were elevated in rejection. The ability to discriminate rejection from quiescence was improved when AlloSure and AlloMap Kidney were used together (AUC, 0.894). Validation of AlloMap Kidney demonstrated the ability to differentiate between rejection and immune quiescence using a range of scores. The diagnostic performance suggests that assessment of the mechanisms of immunologic activity is complementary to allograft injury information derived from AlloSure dd-cfDNA. Together, these biomarkers offer a more comprehensive assessment of allograft health and immune quiescence.

Emerging role of cell-free DNA in kidney transplantation.

Monitoring kidney transplants for rejection conventionally includes serum creatinine, immunosuppressive drug levels, proteinuria, and donor-specific antibody (DSA). Serum creatinine is a late marker of allograft injury, and the predictive ability of DSA regarding risk of rejection is variable. Histological analysis of an allograft biopsy is the standard method for diagnosing rejection but is invasive, inconvenient, and carries risk of complications. There has been a long quest to find a perfect biomarker that noninvasively predicts tissue injury caused by rejection at an early stage, so that diagnosis and treatment could be pursued without delay in order to minimize irreversible damage to the allograft. In this review, we discuss relatively novel research on identifying biomarkers of tissue injury, specifically elaborating on donor-derived cell-free DNA, and its clinical utility.

Design and Methods of the Validating Injury to the Renal Transplant Using Urinary Signatures (VIRTUUS) Study in Children.

Background.Lack of noninvasive diagnostic and prognostic biomarkers to reliably detect early allograft injury poses a major hindrance to long-term allograft survival in pediatric kidney transplant recipients.Methods.Validating Injury to the Renal Transplant Using Urinary Signatures Children’s Study, a North American multicenter prospective cohort study of pediatric kidney transplant recipients, aims to validate urinary cell mRNA and metabolite profiles that were diagnostic and prognostic of acute cellular rejection (ACR) and BK virus nephropathy (BKVN) in adult kidney transplant recipients in Clinical Trials in Organ Transplantation-4. Specifically, we are investigating: (1) whether a urinary cell mRNA 3-gene signature (18S-normalized CD3ε, CXCL10 mRNA, and 18S ribosomal RNA) discriminates biopsies with versus without ACR, (2) whether a combined metabolite profile with the 3-gene signature increases sensitivity and specificity of diagnosis and prognostication of ACR, and (3) whether BKV-VP1 mRNA levels in urinary cells are diagnostic of BKVN and prognostic for allograft failure.Results.To date, 204 subjects are enrolled, with 1405 urine samples, including 144 biopsy-associated samples. Among 424 urine samples processed for mRNA, the median A260:280 ratio (RNA purity) was 1.91, comparable with Clinical Trials in Organ Transplantation-4 (median 1.82). The quality control failure rate was 10%. Preliminary results from urine supernatant showed that our metabolomics platform successfully captured a broad array of metabolites. Clustering of pool samples and overlay of samples from various batches demonstrated platform robustness. No study site effect was noted.Conclusions.Multicenter efforts to ascertain urinary biomarkers in pediatric kidney transplant recipients are feasible with high-quality control. Further study will inform whether these signatures are discriminatory and predictive for rejection and infection.

Abstract 13830: Prediction of Cardiac Rejection Trajectories via Machine Learning Derived Features From Digital Endomyocardial Biopsy Images

Introduction: Cellular rejection occurs in 20-40% of transplant recipients with an increased risk of graft failure. Previously, we developed a model for predicting ISHLT rejection grades via the automated extraction of morphologic features in Endomyocardial biopsy (EMB) images. Considering the frequent discordance between conventional rejection grade and clinical rejection severity, in this work, we sought to identify morphologic features that predict the clinical trajectory of rejection events. Methods: Our study comprised 299 EMBs with grade and trajectory labels. Trajectory labels are based on the development of overt clinical signs of allograft injury as “clinically evident” or “clinically silent”. Morphologic features describing number, spatial arrangement of lymphocytes, and shape, orientation of interstitial fibers were computationally extracted. To identify the top features associated with clinically evident disease, the T-test method was applied across 500 iterations of 3-fold cross validation. In each iteration, a quadratic discriminant analysis model was trained with top 10 features on 2 folds of dataset using trajectory labels (M trj ) and was validated on one hold out test set. This model was trained using grade labels (M grd ) to predict “high” (2R + 3R) or “low” (0R + 1R). To assess feature importance, in each model, the frequency of every feature appearing in the classifier was measured through iterations. Results: The mean area under the receiver operating curve of M trj and M grd was 0.80±0.04 and 0.84±0.02 correspondingly. The top features for predicting grades differ substantially from those for predicting clinical trajectory (Figure 1). Conclusions: The additional features required to predict clinical trajectory vs. rejection grade may explain the discordance between conventional histology and rejection syndrome observed in clinical practice, and highlights the translational potential of computer-assisted histologic analysis of EMBs.

Spot Urine Protein Excretion in the First Year Following Kidney Transplantation Associates With Allograft Rejection Phenotype at 1-Year Surveillance Biopsies: An Observational National-Cohort Study.

Introduction: Urine protein excretion is routinely measured to assess kidney allograft injury, but the diagnostic value of this measurement for kidney transplant pathology remains unclear. Here we investigated whether spot urine protein excretion in the first year following transplantation associates with allograft rejection phenotype at 1-year surveillance biopsies and de-novo occurrence of donor-specific antibodies (DSA).Patients and Methods: This prospective, observational national-cohort study included 139 non-sensitized patients who received a deceased donor kidney transplant between December 2014 and 2018. All patients received basiliximab induction and tacrolimus-based immunosuppression. Estimated protein excretion rate (ePER) was calculated monthly from spot urine protein-to-creatinine ratios. At 1-year, all recipients underwent surveillance graft biopsy and were screened for de-novo DSA. Screening-positive sera were subjected to single antigen bead (SAB) testing. The occurrence of de-novo DSA was determined based on SAB reactivity patterns using a mean fluorescence intensity threshold >1,000.Results: Among the 139 study patients, 27 patients (19%) had histologic evidence of T cell-mediated rejection (TCMR), and 9 patients (7%) had histologic evidence of antibody-mediated rejection (AMR) at 1-year surveillance biopsy. One year after transplant, 19 patients (14%) developed de-novo DSA. Compared with patients without rejection and no de-novo DSA, mixed-effects linear regression analysis showed a significant difference in slope of ePER during the first year in patients with AMR and de-novo DSA at 1-year (46, 95% CI 25–68 mg/day/1.73 m2 per month and 34, 95% CI 20–49 mg/day/1.73 m2 per month, respectively). Patients with vascular TCMR also showed a significant difference in ePER slope over time compared with patients with non-rejection findings (31, 95% CI 9–52 mg/day/1.73 m2 per month). The discriminatory power of ePER for intragraft rejection processes was better in patients with AMR (AUC 0.95, 95% CI 0.90–0.99; P < 0.001) than in those with TCMR (AUC 0.68, 95% CI 0.59–0.79; P = 0.002), with 89% sensitivity and 93% specificity for proteinuria >550 mg/day/1.73m2.Conclusions: An increase in ePER in the first year following kidney transplantation associates with AMR, vascular TCMR and de-novo DSA at 1-year and may be used as a non-invasive clinical marker of intragraft endothelial cell injury.

Incorporation of Donor-derived Cell-free DNA Into Clinical Practice for Renal Allograft Management

Donor-derived cell-free DNA (dd-cfDNA) in plasma is an established noninvasive biomarker for allograft injury and rejection. A single-nucleotide polymorphism (SNP)-based massively multiplexed polymerase chain reaction methodology can be used to quantify dd-cfDNA in kidney transplant recipients. In this study we describe our clinical experience in using a SNP-based dd-cfDNA assay for the management of active rejection in renal transplant recipients. To assess the clinical utility of a clinically available SNP-based massively multiplexed polymerase chain reaction dd-cfDNA assay, we analyzed biopsy data contemporaneous to dd-cfDNA results at 33 participating clinics and calculated the rate of rejection in dd-cfDNA-matched biopsy results. A total of 1347 dd-cfDNA test samples from 879 patients were accessioned from October 3, 2019, to November 2, 2020. The dd-cfDNA testing classified 25.2% (340/1347) of samples as high-risk (dd-cfDNA fraction ≥ 1%). Clinical follow-up was available for 32.1% (109/340) of the high-risk results, which included samples from 28 patients with definitive biopsy results within 2 weeks of dd-cfDNA testing. Pathology reports indicated a 64% (18/28) rate of active rejection in biopsy result-matched samples. Total cfDNA measurements indicated a skewed distribution and a correlation with dd-cfDNA-derived patient risk classification. This is the first report showing the impact of dd-cfDNA on patient management in a multicenter real-world clinical cohort. The data indicate that incorporating dd-cfDNA testing into practice may improve physician decision making regarding renal allograft recipients.

Donor-Derived Cell-Free DNA for Acute Rejection Monitoring in Heart and Lung Transplantation.

Purpose of ReviewAcute allograft rejection is a common cause of morbidity and mortality in heart and lung transplantation. Unfortunately, the current monitoring gold standard—biopsy plus histopathology—has several limitations. Plasma donor-derived cell-free DNA (dd-cfDNA) has emerged as a potentially valuable biomarker for rejection that addresses some of the limitations of biopsy. This review covers the current state of the evidence and future directions for the use of dd-cfDNA in the monitoring of acute rejection.Recent FindingsThe results of several observational cohort studies demonstrate that levels of dd-cfDNA increase in the setting of acute cellular rejection and antibody-mediated rejection in both heart and lung transplant recipients. dd-cfDNA demonstrates acceptable performance characteristics, but low specificity for the detection of underlying injury from rejection or infection. In particular, the high negative predictive value of the test in both heart and lung transplant patients provides the potential for its use as a screening tool for the monitoring of allograft health rather than tissue biopsy alone.SummaryExisting evidence shows that dd-cfDNA is a safe, convenient, and reliable method of acute rejection monitoring in heart and lung transplant recipients. Further studies are required to validate threshold values for clinical use and determine its role in the diagnosis of alternative forms of allograft injury.

Chronic Allograft Injury.

With the incremental improvements in long-term kidney transplant survival, there is renewed focus on what causes failure of the transplanted allograft. Over the past decade, our understanding of the injuries that lead to loss of graft function over time has evolved. Chronic allograft injury includes both immune-mediated and nonimmune-mediated injuries, which may involve the organ donor, the recipient, or both. The targets of injury include the kidney tubular epithelium, the endothelium, and the glomerulus. As a response to injury, there are the expected tissue remodeling and repair processes. However, if inflammation persists, which is not uncommon in the transplant setting, the resulting maladaptive response is matrix deposition and/or fibrosis. This ultimately leads to declining graft function and, finally, failure. With our advancing knowledge of the multiple etiologies and mechanisms, enhanced by more recent cohort studies in humans, there is an opportunity to identify those at greater risk to initiate new strategies to ameliorate the process. Although the most recent studies focus on immune-mediated injuries, there is a critical need to identify both markers of injury and mechanisms of injury. In this review, we highlight the findings of recent studies, highlight the potential therapeutic targets, and identify the continued unmet need for understanding the mechanisms of late graft failure.

Noninvasive Assessment of the Alloimmune Response in Kidney Transplantation.

Transplantation remains the optimal mode of kidney replacement therapy, but unfortunately long-term graft survival after 1year remains suboptimal. The main mechanism of chronic allograft injury is alloimmune, and current clinical monitoring of kidney transplants includes measuring serum creatinine, proteinuria, and immunosuppressive drug levels. The most important biomarker routinely monitored is human leukocyte antigen (HLA) donor-specific antibodies (DSAs) with the frequency based on underlying immunologic risk. HLA-DSA should be measured if there is graft dysfunction, immunosuppression minimization, or nonadherence. Antibody strength is semiquantitatively estimated as mean fluorescence intensity, with titration studies for equivocal cases and for following response to treatment. Determination of invitro C1q or C3d positivity or HLA-DSA IgG subclass analysis remains of uncertain significance, but we do not recommend these for routine use. Current evidence does not support routine monitoring of non-HLA antibodies except anti-angiotensin II type 1 receptor antibodies when the phenotype is appropriate. The monitoring of both donor-derived cell-free DNA in blood or gene expression profiling of serum and/or urine may detect subclinical rejection, although mainly as a supplement and not as a replacement for biopsy. The optimal frequency and cost-effectiveness of using these noninvasive assays remain to be determined. We review the available literature and make recommendations.

Approach to Highly Sensitized Kidney Transplant Candidates and a Positive Crossmatch

Human leukocyte antigen (HLA)-incompatible kidney transplantation offers survival benefit compared with ongoing dialysis. There have been considerable advances in the last decade to allow for increased access to transplant for the HLA-sensitized kidney transplant candidates. These include increased priority in the kidney allocation system, kidney paired donation, and novel desensitization strategies. A better understanding of the role of B cells, plasma cells, and complement and inflammatory cytokines in the pathophysiology of HLA antibody-mediated allograft injury has led to the use of novel therapeutics for desensitization and treatment of antibody-mediated rejection. Here we discuss current approaches to kidney transplantation in HLA-sensitized kidney transplant candidates.

Renal allograft rejection with thrombotic microangiopathy associated with a Kidd blood group system alloantibody

Abstract Introduction/Objective The Kidd blood group antigens are urea transporters found on the surface of red blood cells, renal tubular epithelial cells, and endothelial cells in the renal medulla and vasa recta. While controversial, some reports have described an association between Kidd antigen donor/recipient mismatches and kidney transplant rejection when recipients possess or form anti-Kidd alloantibodies. To date, none of these reports have described development of a thrombotic microangiopathy (TMA) in the renal graft associated with these antibodies. We describe a case of fulminant renal transplant rejection associated with TMA in a patient with anti-Jk(a) alloantibodies who received a deceased-donor kidney transplant (DDKT). Methods/Case Report A 64-year-old woman with end-stage renal disease secondary to AL amyloidosis caused by plasma cell neoplasm received a DDKT associated with delayed graft function. No pre- or post-transplant donor specific antibodies (DSA) were detected, the flow crossmatch testing was negative, and a pre-operative type and screen identified anti-Jk(a) alloantibodies. On post-transplant day 5, her creatinine remained elevated at 6 mg/dL (ref range: 0.4–1.3 mg/dL) with an acute drop in platelets and undetectable haptoglobin. Allograft biopsy showed a combination of TMA with some additional evidence of acute cellular rejection. Tacrolimus was stopped to rule out drug-induced TMA, and the workup showed negative Shiga toxin, normal ADAMTS13 activity, negative atypical HUS genetic testing, and negative antiphospholipid syndrome testing. Genotyping of the donor kidney was positive for the Jk(a) antigen. Eculizumab, IVIG, and a trial of 8 sessions of therapeutic plasma exchange (TPE) were administered. Her creatinine improved (1.93–2.05 mg/dL), indicating a significant antibody-mediated etiology to her delayed graft function. About one month later, her creatinine worsened, and she received another trial of TPE with IVIG and eculizumab. Despite a mild decrease in her creatinine, repeat biopsies showed acute cellular rejection, persistent TMA, and chronic allograft injury. No DSAs were ever detected. Her creatinine never recovered, and she is now dialysis-dependent. Results (if a Case Study enter NA) NA Conclusion We speculate that anti-Jk(a) antibodies interacting with a Jk(a)-positive donor kidney account for graft TMA. This case underscores the potential importance of matching Kidd antigens in kidney transplantation.

Blockade of IL-6/IL-6R Signaling Attenuates Acute Antibody-Mediated Rejection in a Mouse Cardiac Transplantation Model.

Acute antibody-mediated rejection (AAMR) is an important cause of cardiac allograft dysfunction, and more effective strategies need to be explored to improve allograft prognosis. Interleukin (IL)-6/IL-6R signaling plays a key role in the activation of immune cells including B cells, T cells and macrophages, which participate in the progression of AAMR. In this study, we investigated the effect of IL-6/IL-6R signaling blockade on the prevention of AAMR in a mouse model. We established a mouse model of AAMR for cardiac transplantation via presensitization of skin grafts and addition of cyclosporin A, and sequentially analyzed its features. Tocilizumab, anti-IL-6R antibody, and recipient IL-6 knockout were used to block IL-6/IL-6R signaling. We demonstrated that blockade of IL-6/IL-6R signaling significantly attenuated allograft injury and improved survival. Further mechanistic research revealed that signaling blockade decreased B cells in circulation, spleens, and allografts, thus inhibiting donor-specific antibody production and complement activation. Moreover, macrophage, T cell, and pro-inflammatory cytokine infiltration in allografts was also reduced. Collectively, we provided a highly practical mouse model of AAMR and demonstrated that blockade of IL-6/IL-6R signaling markedly alleviated AAMR, which is expected to provide a superior option for the treatment of AAMR in clinic.

Post-infection pulmonary sequelae after COVID-19 among patients with lung transplantation.

BackgroundThere is limited data on outcomes among lung transplant (LT) patients who survive Coronavirus disease 2019 (COVID‐19).MethodsAny single or bilateral LT patients who tested positive for SARS‐CoV‐2 between March 1, 2020, to February 15, 2021 (n = 54) and survived the acute illness were included (final n = 44). Each patient completed at least 3 months of follow‐up (median: 4.5; range 3–12 months) after their index hospitalization for COVID‐19. The primary endpoint was a significant loss of lung functions (defined as > 10% decline in forced vital capacity (FVC) or forced expiratory volume in 1 s (FEV1) on two spirometries, at least 3 weeks apart compared to the pre‐infection baseline).ResultsA majority of the COVID‐19 survivors had persistent parenchymal opacities (n = 29, 65.9%) on post‐infection CT chest. Patients had significantly impaired functional status, with the majority reporting residual disabilities (Karnofsky performance scale score of 70% or worse; n = 32, 72.7%). A significant loss of lung function was observed among 18 patients (40.9%). Three patients met the criteria for new chronic lung allograft dysfunction (CLAD) following COVID‐19 (5.6%), with all three demonstrating restrictive allograft syndrome phenotype. An absolute lymphocyte count < 0.6 × 103/dl and ferritin > 150 ng/ml at the time of hospital discharge was independently associated with significant lung function loss.ConclusionsA significant proportion of COVID‐19 survivors suffer persistent allograft injury. Low absolute lymphocyte counts (ALC) and elevated ferritin levels at the conclusion of the hospital course may provide useful prognostic information and form the basis of a customized strategy for ongoing monitoring and management of allograft dysfunction.TweetTwitter handle: @AmitBangaMDLung transplant patients who survive COVID‐19 suffer significant morbidity with persistent pulmonary opacities, loss of lung functions, and functional deficits. Residual elevation of the inflammatory markers is predictive.

Foregut Dysmotility in the Lung Transplant Patient.

To explore the role of upper gastrointestinal disease in the clinical course of lung transplant patients - including its pathophysiology, diagnostic testing, and treatment options. Gastroesophageal reflux disease (GERD) and foregut motility disorders are more prevalent among end-stage lung disease patients and are associated with poorer outcomes in lung transplant recipients. A proposed mechanism is the exposure of the lung allograft to aspirated contents, resulting in inflammation and rejection. Diagnostic tools to assess for these disorders include multichannel intraluminal impedance and pH (MII-pH) testing, high resolution esophageal manometry (HREM), and gastric emptying scintigraphy. The main treatment options are medical management with acid suppressants and/or prokinetic agents and anti-reflux surgery. In particular, data support the use of early anti-reflux surgery to improve outcomes. Newer diagnostic tools such as MII-pH testing and HREM allow for the identification of both acid and non-acid reflux and esophageal motility disorders, respectively. Recent studies have demonstrated that early anti-reflux surgery within six months post-transplant better protects against allograft injury and pulmonary function decline when compared to late surgery. However, further prospective research is needed to evaluate the short and long-term outcomes of these diagnostic approaches and interventions.

Correlation between BAL CXCR3 chemokines and lung allograft histopathologies: A multicenter study

The histopathologic diagnosis of acute allograft injury is prognostically important in lung transplantation with evidence demonstrating a strong and consistent association between acute rejection (AR), acute lung injury (ALI), and the subsequent development of chronic lung allograft dysfunction (CLAD). The pathogenesis of these allograft injuries, however, remains poorly understood. CXCL9 and CXCL10 are CXC chemokines induced by interferon-γ and act as potent chemoattractants of mononuclear cells. We hypothesized that these chemokines are involved in the mononuclear cell recruitment associated with AR and ALI. We further hypothesized that the increased activity of these chemokines could be quantified as increased levels in the bronchoalveolar lavage fluid. In this prospective multicenter study, we evaluate the incidence of histopathologic allograft injury development during the first-year post-transplant and measure bronchoalveolar CXCL9 and CXCL10 levels at the time of the biopsy. In multivariable models, CXCL9 levels were 1.7-fold and 2.1-fold higher during AR and ALI compared with "normal" biopsies without histopathology. Similarly, CXCL10 levels were 1.6-fold and 2.2-fold higher during these histopathologies, respectively. These findings support the association of CXCL9 and CXCL10 with episodes of AR and ALI and provide potential insight into the pathogenesis of these deleterious events.

A SPECTRUM OF IMMUNOLOGIC EVENTS IS ASSOCIATED WITH ELEVATED DONOR-DERIVED CELL-FREE DNA AFTER LUNG TRANSPLANTATION

TOPIC: Transplantation TYPE: Late Breaking PURPOSE: Chronic lung allograft dysfunction (CLAD)-free survival after lung transplant (LT) according to ISHLT data, remains only 3.16-3.58 years, emphasizing an unmet clinical need for a noninvasive biomarker for surveillance. Here we sought to analyze the use of donor-derived cell-free DNA (dd-cfDNA) for the identification of rejection in LT recipients. METHODS: We performed a single-center, prospective analysis of plasma dd-cfDNA using the Prospera™ test (Natera, Inc., San Carlos) collected with concurrent clinical, fiberoptic bronchoscopy (FOB), transbronchial biopsy (TBBx) and bronchoalveolar lavage (BAL) assessments for diagnosis of acute cellular rejection (ACR, ISHLT Grades A0-A4) and antibody-mediated rejection (AMR). BAL was analyzed with routine microbiologic studies, viral multiplex PCR and cytologic differential cell counts (%) to further define cohorts of CLAD/NRAD (Neutrophilic-responsive Allograft Dysfunction), allograft infection (Infxn) and Stable/Healthy. Nonparametric statistics (Mann-Whitney, p<0.05), cohort median with interquartile range (IQR) and AUROC analyses were performed. RESULTS: A total of 95 dd-cfDNA samples with matched FOB procedures in 72 LT recipients (age: 58±14 years, F:M 50.5:49.5%) were obtained; 6 samples were omitted due to nonspecific histology or confounding conditions. Samples were obtained from patients with native lung diseases: COPD (35%), ILD (52%), CF (2%), PAH (5%), Re-LT (6%) and Other (<1%). Median time post-LT was significantly longer for CLAD/NRAD (852 days, 270-13 515; p=0.005) as compared to Stable (196 days, 90.5-335.5), ACR (212.5 days, 117-3 631), and Infxn (100 days, 81-198) cohorts. BAL Neutrophilia was elevated in individuals with ACR (3.5%, 2-17; p=0.01), CLAD/NRAD (13.5%, 3.5-23.5; p=0.004) and Infxn (8.5%, 0-6; p=0.05) as compared to Stable patients (2%, 1-4). BAL microbiology isolates identified in individuals with allograft infection included: Staphylococcus aureus, Streptococcus viridans, and Pseudomonas aeruginosa. ACR absent from AMR included Grade A1 (15) and A2 (7) in this cohort. Median dd-cfDNA was significantly elevated in the ACR (1.28%, 0.53-3.16; p<0.0001; n=22) and CLAD/NRAD cohorts (1.60%, 0.50-2.53; p=0.008; n=8) as compared to the Stable cohort (0.375%, 0.18-0.70; n=52). No significant difference was seen in the Infxn cohort (0.68%, 0.14-1.24; p=0.46; n=7). An AUC of 0.77 (95%CI: 0.64-0.90) was obtained for distinguishing ACR from Stable samples. Performance of dd-cfDNA for the identification of rejection were determined at cut-offs of 0.5% (77% Sensitivity, 56% Specificity, 27% PPV, 92% NPV) and 1.0% dd-cfDNA (59% Sensitivity, 87% Specificity, 48% PPV, and 91% NPV). PPV and NPV were projected using a prevalence of 17% (OPTN/SRTR, 2021). CONCLUSIONS: Elevated dd-cfDNA levels occur in a spectrum of immunologic events, including ACR and CLAD/NRAD. CLINICAL IMPLICATIONS: The observation of elevated dd-cfDNA in cohorts with BAL neutrophilia may highlight potential value in detection of allograft injury as related to an upregulated IL-8 and Th-17 biology. The elevated dd-cfDNA levels associated with rejection suggest a potential non-invasive molecular tool for surveillance of LT allograft health. DISCLOSURES: Research grant relationship with Natera Please note: 11/18/20-Present Added 06/25/2021 by Brian Keller, source=Web Response, value=Grant/Research Support Advisory Board, Research Grant relationship with CareDx Please note: 3/30/20-Present Added 06/25/2021 by Brian Keller, source=Web Response, value=Grant Support/Honoraria Employee relationship with Natera Please note: October 2020 – Added 06/24/2021 by Michael Olymbios, source=Web Response, value=Salary Research support relationship with Natera Please note: 12/2020-06/2021 Added 06/28/2021 by Justin Rosenheck, source=Web Response, value=Grant/Research Support Employee relationship with Natera, Inc. Please note: 2020- present Added 06/22/2021 by David Ross, source=Web Response, value=Salary Employee relationship with Natera Please note: 2018 - present Added 06/23/2021 by Jonathan Sternberg, source=Web Response, value=Salary