Lung Re-transplantation after prolonged veno-venous extracorporeal membrane oxygenation (ECMO) in a child with chronic lung allograft dysfunction.

BACKGROUND: Extracorporeal Membrane Oxygenation (ECMO) may be used as a bridge to lung transplantation in selected patients with end-stage respiratory failure. Historically, ECMO use in this setting has been associated with poor outcomes Puri V et.al, J Thorac Cardiovasc Surg, 140:427. More recently, technical advances and the implementation of rehabilitation and ambulation while awaiting transplantation on ECMO have led to improved surgical and post-transplant outcomes Kirkby S et.al, J Thorac Dis, 6:1024. METHODS: We illustrate the case of a 6-year-old child who received prolonged ECMO support as a bridge to lung re-transplantation secondary to Chronic Lung Allograft Dysfunction (CLAD). RESULTS: Early rehabilitation was key in improving the overall pre-transplant conditioning during ECMO. CONCLUSIONS: Despite challenges associated with awake/ambulatory ECMO, the use of this strategy as a bridge to lung transplantation is feasible and has resulted in improved pre-transplant conditioning and post-transplant outcomes.

Late effects in survivors of post-transplant lymphoproliferative disease.

BACKGROUND: Treatment of post-transplant lymphoproliferative disease (PTLD) varies, with only some patients receiving chemotherapy. Concern for chemotherapy toxicities may influence treatment decisions as little is known regarding the late effects (LE) in PTLD survivors. This report characterizes LE in PTLD survivors at our institution. PROCEDURE: Pediatric patients (0-18 years old) diagnosed with PTLD from 1990 to 2020 were examined. All patients included survived 6 months after completing chemotherapy or were 6 months from diagnosis if received no chemotherapy. Treatment with anti-CD20 antibody (rituximab) alone was not considered chemotherapy. Toxicities were classified per Common Terminology Criteria for Adverse Events Version 5.0. Chi-square tests assessed differences between categorical groups, or Fischer's exact test or the Fischer-Freeman-Halton exact test for limited sample sizes. RESULTS: Of the 44 patients included, 24 (55%) were treated with chemotherapy. Twenty-four (55%) were alive at last follow-up. Chemotherapy was not associated with differences in survival (odds ratio [OR] 1.40, confidence interval [CI]: 0.42-4.63; p = .31). All patients experienced LE. Grade 3 toxicity or higher was experienced by 82% of patients with no difference in incidence (OR 1.20, CI: 0.27-5.80; p > .99) or median toxicity grade (3.00 vs. 4.00, p = .21) between treatment groups. Patients who received chemotherapy were more likely to experience blood and lymphatic toxicity (58% vs. 25%, p = .03) and cardiac toxicity (46% vs. 15%, p = .03), but less likely to have infections (54% vs. 85%, p = .03). CONCLUSIONS: Survivors of PTLD experience LE including late mortality regardless of chemotherapy exposure. Further investigation to better understand LE could optimize upfront therapy for children with PTLD and improve outcomes.

Auto-inflammation and auto-immunity pathways are associated with emergence of BOS in pediatric lung transplantation.

BACKGROUND: Long-term survival after lung transplantation (LTx) is limited by chronic lung allograft dysfunction (CLAD). METHODS: We report an analysis of cytokine profiles in bronchoalveolar lavage samples collected during a prospective multicenter non-interventional trial primarily designed to determine the impact of community-acquired respiratory viral infections (CARV) in outcomes after pediatric LTx. In this analysis, we identify potential biomarkers of auto-inflammation and auto-immunity associated with survival and risk of bronchiolitis obliterans (BOS) after LTx with cytokine analysis of bronchoalveolar lavage fluid (BALF) from 61 pediatric recipients. RESULTS: Higher IL-23 (p = .048) and IL-31 (p = .035) levels were associated with the risk of BOS, and lower levels of epithelial growth factor (EGF) (p = .041) and eotaxin (EOX) (p = .017) were associated with BOS. Analysis using conditional inference trees to evaluate cytokines at each visit associated with survival identified soluble CD30 (p < .001), pro-inflammatory cytokine IL-23 (p = .02), and sTNFRI (p = .01) below cutoff levels as associated with BOS-free survival. CONCLUSIONS: Our results indicate that post-LTx survival in children may be linked to activation of alternate pathways of the immune system that affect airway remodeling in addition to activation of "classical" pathways that have been described in adult LTx recipients. These may indicate pathways to target for intervention.

Biologic characterization of ABCA3 variants in lung tissue from infants and children with ABCA3 deficiency.

ABCA3 is a phospholipid transporter protein required for surfactant assembly in lamellar bodies of alveolar type II cells. Biallelic pathogenic ABCA3 variants cause severe neonatal respiratory distress syndrome or childhood interstitial lung disease. However, ABCA3 genotype alone does not explain the diversity in disease presentation, severity, and progression. Additionally, monoallelic ABCA3 variants have been reported in infants and children with ABCA3-deficient phenotypes. The effects of most ABCA3 variants identified in patients have not been characterized at the RNA level. ABCA3 allele-specific expression occurs in some cell types due to epigenetic regulation. We obtained lung tissue at transplant or autopsy from 16 infants and children with ABCA3 deficiency due to compound heterozygous ABCA3 variants for biologic characterization of the predicted effects of ABCA3 variants at the RNA level and determination of ABCA3 allele expression. We extracted DNA and RNA from frozen lung tissue and reverse-transcribed cDNA from mRNA. We performed Sanger sequencing to assess allele-specific expression by comparing the heights of variant nucleotide peaks in amplicons from genomic DNA and cDNA. We found similar genomic and cDNA variant nucleotide peak heights and no evidence of allele-specific expression among explant or autopsy samples with biallelic missense ABCA3 variants (n = 6). We observed allele-specific expression of missense alleles in trans with frameshift (n = 4) or nonsense (n = 1) variants, attributable to nonsense-mediated decay. The missense variant c.53 A > G;p.Gln18Arg, located near an exon-intron junction, encoded abnormal splicing with skipping of exon 4. Biologic characterization of ABCA3 variants can inform discovery of variant-specific disease mechanisms.

Posttraumatic stress and medication adherence in pediatric transplant recipients.

Adolescent transplant recipients may encounter a range of potentially traumatic events (PTEs) pre- and posttransplant, yet little is known about the relationship between posttraumatic stress symptoms (PTSS) and medication adherence in this population. In the present study, adolescent recipients and caregivers completed psychosocial questionnaires at enrollment. Outpatient tacrolimus trough level data were collected over 1 year to calculate the Medication Level Variability Index (MLVI), a measure of medication adherence. Nonadherence (MLVI ≥2) was identified in 34.8% of patients, and most (80.7%) reported ≥1 PTE exposure. Levels of PTSS indicating likely posttraumatic stress disorder (PTSD) were endorsed by 9.2% of patients and 43.7% of caregivers. PTSS and MLVI were significantly correlated in the liver subgroup (r = .30, p = .04). Hierarchical multivariable linear regression analyses revealed overall patient PTSS were significantly associated with QoL (p < .001). PTEs are common in adolescent recipients; a minority may meet criteria for PTSD. PTSS screening to identify nonadherence risk requires further investigation and addressing PTSS may improve QoL. Caregivers appear at greater risk for PTSD and may require their own supports. The study was approved by each participating center's Institutional Review Board.

CTOTC-08: A multicenter randomized controlled trial of rituximab induction to reduce antibody development and improve outcomes in pediatric lung transplant recipients.

We conducted a randomized, placebo-controlled, double-blind study of pediatric lung transplant recipients, hypothesizing that rituximab plus rabbit anti-thymocyte globulin induction would reduce de novo donor-specific human leukocyte antigen antibodies (DSA) development and improve outcomes. We serially obtained clinical data, blood, and respiratory samples for at least one year posttransplant. We analyzed peripheral blood lymphocytes by flow cytometry, serum for antibody development, and respiratory samples for viral infections using multiplex PCR. Of 45 subjects enrolled, 34 were transplanted and 27 randomized to rituximab (n = 15) or placebo (n = 12). No rituximab-treated subjects versus five placebo-treated subjects developed de novo DSA with mean fluorescence intensity >2000. There was no difference between treatment groups in time to the primary composite outcome endpoint (death, bronchiolitis obliterans syndrome [BOS] grade 0-p, obliterative bronchiolitis or listing for retransplant). A post-hoc analysis substituting more stringent chronic lung allograft dysfunction criteria for BOS 0-p showed no difference in outcome (p = .118). The incidence of adverse events including infection and rejection episodes was no different between treatment groups. Although the study was underpowered, we conclude that rituximab induction may have prevented early DSA development in pediatric lung transplant recipients without adverse effects and may improve outcomes (Clinical Trials: NCT02266888).

Community-Acquired Respiratory Viruses Post-Lung Transplant.

Survival in lung transplant recipients (LTRs) lags behind heart, liver, and kidney transplant, in part due to the direct and indirect effects of infection. LTRs have increased susceptibility to infection due to the combination of a graft continually exposed to the outside world, multiple mechanisms for impaired mucus clearance, and immunosuppression. Community-acquired respiratory viral infections (CARVs) are common in LTRs. Picornaviruses have roughly 40% cumulative incidence followed by respiratory syncytial virus and coronaviruses. Although single-center retrospective and prospective series implicate CARV in rejection and mortality, conclusive evidence for and well-defined mechanistic links to long-term outcome are lacking. Treatment of viral infections can be challenging except for influenza. Future studies are needed to develop better treatments and clarify the links between CARV and long-term outcomes.

Survival implications of prescription opioid and benzodiazepine use in lung transplant recipients: Analysis of linked transplant registry and pharmacy fill records.

BACKGROUND: Prescription opioid and benzodiazepine use have been associated with morbidity and mortality among some groups of solid organ transplant recipients, but implications for outcomes among lung transplant patients are not well described. METHODS: We conducted a retrospective cohort study using linked national transplant registry and pharmaceutical records to characterize the associations between benzodiazepine and opioid prescription fills in the years before and after lung transplant (2006-2017), with risk-adjusted posttransplant survival (adjusted hazard ratio, LCLaHRUCL). RESULTS: Among 11,568 recipients, 33.7% filled an opioid prescription, and 25.8% filled a benzodiazepine prescription before transplant. Compared to patients without prescriptions, those who filled both short- and long-acting benzodiazepine prescriptions before transplant had 2-fold higher mortality in the first year posttransplant (aHR, 1.392.123.21), after adjustment for baseline factors and opioid fills, while pretransplant opioid fills were not associated with posttransplant mortality after adjustment for benzodiazepine fills. Pretransplant opioid and benzodiazepine use strongly predicted more use after transplant. Fills of both short- and long-acting benzodiazepines in the first year posttransplant were associated with 77% increased mortality >1-to-2 years posttransplant (aHR, 1.061.772.96). Compared with no posttransplant opioid fills, there was a dose-dependent association between first-year opioid fills and subsequent adjusted mortality risk (level 2: aHR, 1.171.501.92 to level 4: aHR, 1.562.012.59). These effects were independent, and interactions were not detected. CONCLUSIONS: Benzodiazepine prescription fills before and after lung transplant, and opioid fills after transplant, are independently associated with posttransplant mortality. Review of benzodiazepine and opioid use history is relevant to risk-stratifying patients before and after lung transplant.

Remote intervention engagement and outcomes in the Clinical Trials in Organ Transplantation in Children consortium multisite trial.

Remote interventions are increasingly used in transplant medicine but have rarely been rigorously evaluated. We investigated a remote intervention targeting immunosuppressant management in pediatric lung transplant recipients. Patients were recruited from a larger multisite trial if they had a Medication Level Variability Index (MLVI) ≥2.0, indicating worrisome tacrolimus level fluctuation. The manualized intervention included three weekly phone calls and regular follow-up calls. A comparison group included patients who met enrollment criteria after the subprotocol ended. Outcomes were defined before the intent-to-treat analysis. Feasibility was defined as ≥50% of participants completing the weekly calls. MLVI was compared pre- and 180 days postenrollment and between intervention and comparison groups. Of 18 eligible patients, 15 enrolled. Seven additional patients served as the comparison. Seventy-five percent of participants completed ≥3 weekly calls; average time on protocol was 257.7 days. Average intervention group MLVI was significantly lower (indicating improved blood level stability) at 180 days postenrollment (2.9 ± 1.29) compared with pre-enrollment (4.6 ± 2.10), p = .02. At 180 days, MLVI decreased by 1.6 points in the intervention group but increased by 0.6 in the comparison group (p = .054). Participants successfully engaged in a long-term remote intervention, and their medication blood levels stabilized. NCT02266888.

Midterm outcomes of the Potts shunt for pediatric pulmonary hypertension, with comparison to lung transplant.

OBJECTIVE: For children with severe pulmonary hypertension, addition of Potts shunt to a comprehensive palliation strategy might improve the outcomes afforded by medications and delay lung transplantation. METHODS: A prospective analysis was conducted of all children undergoing Potts shunt (first performed in 2013) or bilateral lung transplant for pulmonary hypertension from 1995 to present. RESULTS: A total of 23 children underwent Potts shunt (20 surgical, 3 transcatheter), and 31 children underwent lung transplant. All children with Potts shunt had suprasystemic right ventricle pressures despite maximal medical treatment. In the majority of patients, the Potts shunt was performed through a left thoracotomy approach (90%, 18/20), by direct anastomosis (65%, 13/20), and without the use of extracorporeal support (65%, 13/20). Perioperative outcomes after Potts shunt were superior to lung transplant including mechanical ventilation time (1.3 vs 10.2 days, P = .019), median hospital length of stay (9.8 vs 34 days, P = .012), and overall complication rate (35% [7/20] vs 81% [25/31], P = .003). Risk factors for operative mortality after Potts shunt (20%, 4/20; compared with 6%, 2/31 for lung transplant, P = .195) included preoperative extracorporeal membrane oxygenation and significant right ventricle dysfunction. In midterm follow-up (median 1.8, maximum 6.1 years), patients with Potts shunt had durable equalization of right ventricle/left ventricle pressures and improved functional status. There was no significant survival difference in patients with Potts shunt and patients with lung transplant (P = .258). CONCLUSIONS: Potts shunt is an effective palliation for children with suprasystemic pulmonary hypertension that may become part of a strategy to maximize longevity and functional status for these challenging patients.

Epidemiology and persistence of rhinovirus in pediatric lung transplantation.

BACKGROUND: Infection with rhinovirus (HRV) occurs following pediatric lung transplantation. Prospective studies documenting frequencies, persistence, and progression of HRV in this at-risk population are lacking. METHODS: In the Clinical Trials in Organ Transplant in Children prospective observational study, we followed 61 lung transplant recipients for 2 years. We quantified molecular subtypes of HRV in serially collected nasopharyngeal (NP) and bronchoalveolar lavage (BAL) samples and correlated them with clinical characteristics. RESULTS: We identified 135 community-acquired respiratory infections (CARV) from 397 BAL and 480 NP samples. We detected 93 HRV events in 42 (68.8%) patients, 22 of which (23.4%) were symptomatic. HRV events were contiguous with different genotypes identified in 23 cases, but symptoms were not preferentially associated with any particular species. Nine (9.7%) HRV events persisted over multiple successive samples for a median of 36 days (range 18-408 days). Three persistent HRV were symptomatic. When we serially measured forced expiratory volume in one second (FEV1) in 23 subjects with events, we did not observe significant decreases in lung function over 12 months post-HRV. CONCLUSION: In conjunction with our previous reports, our prospectively collected data indicate that molecularly heterogeneous HRV infections occur commonly following pediatric lung transplantation, but these infections do not negatively impact clinical outcomes.

Ethical considerations regarding heart and lung transplantation and mechanical circulatory support during the COVID-19 pandemic: an ISHLT COVID-19 Task Force statement.

To understand the challenges for thoracic transplantation and mechanical circulatory support during the current coronavirus disease 2019 pandemic, we propose separating the effects of the pandemic into 5 distinct stages from a healthcare system perspective. We discuss how the classical ethical principles of utility, justice, and efficiency may need to be adapted, and we give specific recommendations for thoracic transplantation and mechanical circulatory support centers to balance their clinical decisions and strategies for advanced heart and lung disease during the current pandemic.

Distinct molecular and immunological properties of circulating exosomes isolated from pediatric lung transplant recipients with bronchiolitis obliterans syndrome - a retrospective study.

Long-term success following human lung transplantation is poor due to chronic rejection. We demonstrated circulating exosomes of lung origin during acute and chronic lung allograft rejection. We analyzed plasma from pediatric lung transplant recipients (LTxRs) enrolled in the CTOT-C-03 to determine whether circulating exosomes are released into circulation during bronchiolitis obliterans syndrome (BOS). Plasma exosomes were isolated, and human leukocyte antigens (HLA) were detected. Exosomes were analyzed for lung self-antigens (SAgs), co-stimulatory molecules transcription factors, major histocompatibility complex class II (MHC-II), adhesion molecules, and 20S proteasome. Mice were immunized with exosomes from BOS or stable to determine their immunogenicity. Circulating exosomes from BOS LTxRs contained increased levels of SAgs, donor HLA class I, MHC-II, transcription factors, co-stimulatory molecules, and 20S proteasome compared with stable. Serial analysis of exosomes containing SAgs demonstrated that exosomes are detectable in the circulation before BOS. Mice immunized with exosomes from BOS, or stable, demonstrated that exosomes from BOS are distinct in inducing both humoral and cellular immune responses to SAgs. Circulating exosomes from BOS LTxRs elicit distinct humoral and cellular response. In addition, detection of SAgs on circulatory exosomes 12 months before diagnosis of BOS suggest that exosomes could serve as biomarker.

Perceived barriers to medication adherence remain stable following solid organ transplantation.

Perceived barriers to adherence have previously been investigated in SOT to identify plausible intervention targets to improve adherence and transplant outcomes. Fifteen centers in CTOTC enrolled patients longitudinally. Patients >8 years completed Adolescent Scale(AMBS) at two visits at least 6 months apart in the first 17 months post-transplant while their guardians completed PMBS. Differences over time for pre-identified AMBS/PMBS factors were analyzed. Perceived barrier reporting impact on subsequent TAC levels was assessed. A total of 123 patients or their guardians completed PMBS or AMBS. Twenty-six were 6-11 years and 97 were ≥12. The final cohort consisted of kidney (66%), lung (19%), liver (8%), and heart (7%) recipients. Unadjusted analysis showed no statistically significant change in reported barriers from visit 1 (median 2.6 months, range 1.2-3.7 post-transplant) to visit 2 (median 12, range 8.9-16.5). Of 102 patients with TAC levels, 74 had a single level reported at both visits. The factor of "Disease frustration" was identified through the PMBS/AMBS questions about fatigue around medication and disease. Each point increase in "disease frustration" at visit 1 on the AMBS/PMBS doubled the odds of a lower-than-threshold TAC level at visit 2. No clear change in overall level of perceived barriers to medication adherence in the first year post-transplant was seen in pediatric SOT. However, disease frustration early post-transplant was associated with a single subtherapeutic TAC levels at 12 months. A brief screening measure may allow for early self-identification of risk.

Absence of evidence that respiratory viral infections influence pediatric lung transplantation outcomes: Results of the CTOTC-03 study.

Based on reports in adult lung transplant recipients, we hypothesized that community-acquired respiratory viral infections (CARVs) would be a risk factor for poor outcome after pediatric lung transplant. We followed 61 pediatric lung transplant recipients for 2+ years or until they met a composite primary endpoint including bronchiolitis obliterans syndrome/obliterative bronchiolitis, retransplant, or death. Blood, bronchoalveolar lavage, and nasopharyngeal specimens were obtained with standard of care visits. Nasopharyngeal specimens were obtained from recipients with respiratory viral symptoms. Respiratory specimens were interrogated for respiratory viruses by using multiplex polymerase chain reaction. Donor-specific HLA antibodies, self-antigens, and ELISPOT reactivity were also evaluated. Survival was 84% (1 year) and 68% (3 years). Bronchiolitis obliterans syndrome incidence was 20% (1 year) and 38% (3 years). The primary endpoint was met in 46% of patients. CARV was detected in 156 patient visits (74% enterovirus/rhinovirus). We did not find a relationship between CARV recovery from respiratory specimens and the primary endpoint (hazard ratio 0.64 [95% confidence interval: 0.25-1.59], P = .335) or between CARV and the development of alloimmune or autoimmune humoral or cellular responses. These findings raise the possibility that the immunologic impact of CARV following pediatric lung transplant is different than that observed in adults.

Usefulness of gene expression profiling of bronchoalveolar lavage cells in acute lung allograft rejection.

BACKGROUND: Chronic lung allograft dysfunction (CLAD) is the main limitation to long-term survival after lung transplantation. Because effective therapies are lacking, early identification and mitigation of risk factors is a pragmatic approach to improve outcomes. Acute cellular rejection (ACR) is the most pervasive risk factor for CLAD, but diagnosis requires transbronchial biopsy, which carries risks. We hypothesized that gene expression in the bronchoalveolar lavage (BAL) cell pellet (CP) could replace biopsy and inform on mechanisms of CLAD. METHODS: We performed RNA sequencing on BAL CPs from 219 lung transplant recipients with A-grade ACR (n = 61), lymphocytic bronchiolitis (n = 58), infection (n = 41), or no rejection/infection (n = 59). Differential gene expression was based on absolute fold difference >2.0 and Benjamini-adjusted p-value ≤0.05. We used the Database for Annotation, Visualization and Integrated Discovery Bioinformatics Resource for pathway analyses. For classifier modeling, samples were randomly split into training (n = 154) and testing sets (n = 65). A logistic regression model using recursive feature elimination and 5-fold cross-validation was trained to optimize area under the curve (AUC). RESULTS: Differential gene expression identified 72 genes. Enriched pathways included T-cell receptor signaling, natural killer cell-mediated cytotoxicity, and cytokine-cytokine receptor interaction. A 4-gene model (AUC = 0.72) and classification threshold defined in the training set exhibited fair performance in the testing set; accuracy was 76%, specificity 82%, and sensitivity 60%. In addition, classification as ACR was associated with worse CLAD-free survival (hazard ratio = 2.42; 95% confidence interval = 1.29-4.53). CONCLUSIONS: BAL CP gene expression during ACR is enriched for immune response pathways and shows promise as a diagnostic tool for ACR, especially ACR that is a precursor of CLAD.