Detection, classification, and management of rejection after lung transplantation

Serum and tissue biomarkers of plasma cell-rich rejection in liver transplant recipients

The distinction between autoimmune and alloimmune reactions in liver transplant recipients can be challenging. Plasma cell-rich rejection (PCRR), previously known as de novo autoimmune hepatitis or plasma cell hepatitis, is an atypical and underrecognized form of allograft rejection observed post-liver transplantation, often in conjunction with features of T cell-mediated and antibody-mediated rejection. If PCRR is not recognized and treated with prompt immunosuppressive augmentation, patients can develop advanced hepatic fibrosis, necroinflammation, and allograft failure. Given the significant morbidity and mortality associated with PCRR, there exists a need to develop noninvasive biomarkers which can be used in screening, diagnosis, and treatment monitoring of PCRR. This study is a literature review of candidate serum-based and tissue-based biomarkers in adult and pediatric liver transplant PCRR. We also discuss biomarkers from plasma cell-rich processes observed in other disease states and other organ transplant recipients that might be tested in liver transplant PCRR. We conclude with proposed future directions in which biomarker implementation into clinical practice could lead to advances in personalized management of PCRR.

[Risk analysis applied to the monitoring of immunosuppressor concentrations in lung transplant recipients]

Mastering and monitoring immunosuppressant concentrations is central to the care of lung transplant patients and involves multiple stakeholders. The objective is to conduct a risk analysis to evaluate the impact of various actions taken. The lung transplantation team was convened to carry out a failure mode effect analysis. The process was divided into stages where different risks were identified. The risk priority number (RPN) (severity, frequency, detectability) and risk level of criticality (frequency, severity) were established before implementation of actions (before 2009) and then after (in 2022) to classify risks according to four levels of criticality. The implemented actions included the establishment of a quality assurance process, computerization of monitoring, and double analysis by a physician/pharmacist pair. Thirty-two risks were identified during the four stages of the process: biological sampling (n=13), reception (n=3), analysis and treatment of levels (n=5), transmission of information/prescriptions to the patient (n=11). The total raw RPN (before 2009) was 839, with 12 major risks. The current total RPN (in 2022) was 452 (a decrease of 46.1%), with 7 major risks identified. The analysis enabled the objective evaluation of the effectiveness of the actions taken. The most secure stage of the process is the reception of residual level results. Efforts should focus on empowering and involving patients, as well as engaging local stakeholders in collaboration with the specialized transplantation team.

Thirty years of lung transplantation: development of postoperative outcome and survival over three decades

Background

Lung transplantation (LuTX) can be the last resort for patients with end-stage lung diseases. In the last decades, improvements were implemented in transplant medicine, from immunosuppression throughout preservation of the donor organ to enhance lung allograft survival. This retrospective study aims to illustrate the development of the LuTX-program at the University Hospital of Munich, LMU, Munich, Germany, since its launch in 1990 by depicting and comparing postoperative outcome.

Methods

We analyzed all LuTX performed from 1990 to 2019. Data was collected on indication for transplantation (TX), date, type (double/single) and postoperative survival. Survival analysis and Kaplan-Meier estimator were used to identify factors that are detrimental to post-LuTX-outcome.

Results

A total of 1,054 LuTX were performed over 30 years, comprising overall 1,024 patients (30 retransplantations). The best results regarding five-year survival rates (5-YSR) were observed in patients with lymphangioleiomyomatosis (LAM) and hypersensitivity pneumonitis (HP) (5-YSR: LAM: 78.6%, HP: 73.6%). We could show that besides that the type of LuTX played a crucial role in post-TX survival, depicting double superior to single LuTX (5-YSR: single: 47.2%, double: 64.5%). Additionally, cytomegalovirus (CMV) risk constellation (high/intermediate risk; P=0.02) and infection (P<0.001) were identified as risk factors for deteriorated survival.

Conclusions

Data analysis demonstrates that the field of LuTX has undergone enormous progress over the years. Therapeutic advances and improvements in interdisciplinary cooperation, pre- and postoperative management, changes in immunosuppressive medication, diagnosis and treatment of allograft rejections have clearly improved lung allograft and patient survival.

Successful use of therapeutic plasma exchange for the management of acute lung transplant rejection secondary to immune checkpoint inhibitor therapy

The use of immune checkpoint inhibitors (ICIs) in individuals with a history of solid organ transplantation is fraught with the emergence of solid organ transplantation rejection (SOTR). The current recommendations for the management of SOTRs secondary to ICI include the use of high-dose steroids along with the escalation of immunosuppressive therapy. Therapeutic Plasma Exchange (TPE) has been described to be effective in managing various immune-related toxicities, however, the data for using TPE in the setting of acute SOTRs induced by ICIs are limited. Herein, we describe the successful use of TPE in a patient with a history of bilateral lung transplantation who developed an episode of mixed acute cellular and antibody-mediated lung transplant rejection after a single dose of PD-1 inhibitor Pembrolizumab for the treatment of underlying melanoma.

Efficacy of surveillance bronchoscopy versus clinically indicated bronchoscopy for detection of acute lung transplant rejection: a systematic review and meta-analysis

Background

Acute allograft rejection after lung transplantation significantly increases the risk of developing bronchiolitis obliterans syndrome, a form of chronic lung allograft dysfunction and the leading cause of mortality beyond the initial post-transplantation year. There are two diagnostic approaches available for monitoring lung transplant recipients: clinically indicated bronchoscopy (CIB) and surveillance bronchoscopy (SB). The efficacy of both methods and their relative superiority in detecting acute rejection have not been conclusively determined.

Methods

We systematically searched the MEDLINE, Embase, Cochrane and Scopus databases from inception until 10 October 2023 for prospective studies comparing the efficacy of SB and CIB. Meta-analysis using a random effects model was performed for three observational cohort studies, totalling 122 patients with 527 bronchoscopies.

Results

Overall, neither SB nor CIB had a higher likelihood of detecting acute lung transplant rejection of any grade. Subsequent subgroup analyses showed no advantage for SB in detecting minimal rejection (grade A1), but an inverse association was observed for higher-grade rejection.

Conclusion

In conclusion, our study found no significant difference in detecting acute lung transplant rejection between SB and CIB. However, due to the limited number of studies and small sample sizes, larger prospective studies are urgently needed to definitely determine whether there truly exists no difference between SB and CIB in detecting acute rejection, particularly A1 minimal rejection.

Lung transplantation: Current insights and outcomes

Until now, the ability to predict or retard immune-mediated rejection events after lung transplantation is still limited due to the lack of specific biomarkers. The pressing need remains to early diagnose or predict the onset of chronic lung allograft dysfunction (CLAD) and its differential phenotypes that is the leading cause of death. Omics technologies (mainly genomics, epigenomics, and transcriptomics) combined with advanced bioinformatic platforms are clarifying the key immune-related molecular routes that trigger early and late events of lung allograft rejection supporting the biomarker discovery. The most promising biomarkers came from genomics. Both unregistered and NIH-registered clinical trials demonstrated that the increased percentage of donor-derived cell-free DNA in both plasma and bronchoalveolar lavage fluid showed a good diagnostic performance for clinically silent acute rejection events and CLAD differential phenotypes. A further success arose from transcriptomics that led to development of Molecular Microscope® Diagnostic System (MMDx) to interpret the relationship between molecular signatures of lung biopsies and rejection events. Other immune-related biomarkers of rejection events may be exosomes, telomer length, DNA methylation, and histone-mediated neutrophil extracellular traps (NETs) but none of them entered in registered clinical trials. Here, we discuss novel and existing technologies for revealing new immune-mediated mechanisms underlying acute and chronic rejection events, with a particular focus on emerging biomarkers for improving precision medicine of lung transplantation field.

Pseudomonas aeruginosa infection correlates with high MFI donor-specific antibody development following lung transplantation with consequential graft loss and shortened CLAD-free survival

BACKGROUND

Donor-specific antibodies (DSAs) are common following lung transplantation (LuTx), yet their role in graft damage is inconclusive. Mean fluorescent intensity (MFI) is the main read-out of DSA diagnostics; however its value is often disregarded when analyzing unwanted post-transplant outcomes such as graft loss or chronic lung allograft dysfunction (CLAD). Here we aim to evaluate an MFI stratification method in these outcomes.

METHODS

A cohort of 87 LuTx recipients has been analyzed, in which a cutoff of 8000 MFI has been determined for high MFI based on clinically relevant data. Accordingly, recipients were divided into DSA-negative, DSA-low and DSA-high subgroups. Both graft survival and CLAD-free survival were evaluated. Among factors that may contribute to DSA development we analyzed Pseudomonas aeruginosa (P. aeruginosa) infection in bronchoalveolar lavage (BAL) specimens.

RESULTS

High MFI DSAs contributed to clinical antibody-mediated rejection (AMR) and were associated with significantly worse graft (HR: 5.77, p < 0.0001) and CLAD-free survival (HR: 6.47, p = 0.019) compared to low or negative MFI DSA levels. Analysis of BAL specimens revealed a strong correlation between DSA status, P. aeruginosa infection and BAL neutrophilia. DSA-high status and clinical AMR were both independent prognosticators for decreased graft and CLAD-free survival in our multivariate Cox-regression models, whereas BAL neutrophilia was associated with worse graft survival.

CONCLUSIONS

P. aeruginosa infection rates are elevated in recipients with a strong DSA response. Our results indicate that the simultaneous interpretation of MFI values and BAL neutrophilia is a feasible approach for risk evaluation and may help clinicians when to initiate DSA desensitization therapy, as early intervention could improve prognosis.

Oversizing lung allografts deteriorates outcomes in patients with pulmonary fibrosis

BACKGROUND

Lung transplantation is the only curative treatment for patients with end-stage pulmonary fibrosis. It is still under debate whether over- or undersizing of lung allografts is preferably performed regarding the postoperative outcome. We therefore analyzed our data using predicted total lung capacity to compare size mismatches.

METHODS

Patient records were retrospectively reviewed. Three groups were formed, 1 including patients with a donor-recipients pTLC ratio (DRPR) of <1.0 (undersized group), the second with a DRPR of ≥1.0 and <1.1 (size-matched group), and the third group with a DRPR of ≥1.1 (oversized group). Outcomes were evaluated using chi-square test and Kruskall-Wallis test as well as Kaplan-Meier analysis, competing risk analysis, and multivariable analysis, respectively.

RESULTS

Between January 2010 and May 2023, among the 1501 patients transplanted at our institution, 422 (28%) patients were included, 26 (2%) patients forming the oversized group (median DRPR: 1.14), 101 (7%) patients forming the size-matched group (median DRPR: 1.03), and 296 (20%) patients forming the undersized group (median DRPR: 0.92). Patients from the oversized group had a higher PGD grade 3 rate at 24 (p < 0.001), 48 (p < 0.001), and 72 (p = 0.039) hours after transplantation as well as a higher in-hospital mortality compared to the undersized group (p = 0.033). The long-term survival was also better in the undersized group compared to the oversized group (p = 0.011) and to the size-matched group (p = 0.01).

CONCLUSIONS

Oversizing lung allografts more than 10% deteriorated early postoperative outcomes and long-term survival in patients with pulmonary fibrosis.

Acute rejection post lung transplant

PURPOSE OF REVIEW

To review what is currently known about the pathogenesis, diagnosis, treatment, and prevention of acute rejection (AR) in lung transplantation.

RECENT FINDINGS

Epigenomic and transcriptomic methods are gaining traction as tools for earlier detection of AR, which still remains primarily a histopathologic diagnosis.

SUMMARY

Acute rejection is a common cause of early posttransplant lung graft dysfunction and increases the risk of chronic rejection. Detection and diagnosis of AR is primarily based on histopathology, but noninvasive molecular methods are undergoing investigation. Two subtypes of AR exist: acute cellular rejection (ACR) and antibody-mediated rejection (AMR). Both can have varied clinical presentation, ranging from asymptomatic to fulminant ARDS, and can present simultaneously. Diagnosis of ACR requires transbronchial biopsy; AMR requires the additional measuring of circulating donor-specific antibody (DSA) levels. First-line treatment in ACR is increased immunosuppression (pulse-dose or tapered dose glucocorticoids); refractory cases may need antibody-based lymphodepletion therapy. First line treatment in AMR focuses on circulating DSA removal with B and plasma cell depletion; plasmapheresis, intravenous human immunoglobulin (IVIG), bortezomib, and rituximab are often employed.

Impact of Early Tracheostomy After Lung Transplantation: A National Analysis

BACKGROUND

Prolonged mechanical ventilation is common among lung transplant recipients, affecting nearly one-third of patients. Tracheostomy has been shown as a beneficial alternative to endotracheal intubation, but delays in tracheostomy tube placement persist. To date, no large-scale study has investigated the effect of tracheostomy timing on posttransplant outcomes.

METHODS

All adults receiving tracheostomy after primary, isolated lung transplantation were identified in the 2016 to 2020 Nationwide Readmissions Database. Early tracheostomy was defined as placement before postoperative day 8 based on exploratory cohort analysis. Multivariable regression was used to evaluate the association of early tracheostomy with in-hospital mortality, select posttransplant complications, and resource utilization.

RESULTS

Of an estimated 11,048 patients undergoing first-time lung transplantation, 1509 required a tracheostomy in the postoperative period, with 783 (51.9%) comprising the early cohort. After entropy balancing and risk adjustment, early tracheostomy placement was associated with reduced odds of death (adjusted odds ratio, 0.59; 95% CI, 0.36-0.97) and posttransplant infection (adjusted odds ratio, 0.54; 95% CI, 0.35-0.82). Further, tracheostomy within 1 week of transplantation was associated with decreased length of stay (β-coefficient, -16.5 days; 95% CI, -25.3 to -7.6 days) and index hospitalization costs (β-coefficient, -$97,600; 95% CI, -$153,000 to -$42,100).

CONCLUSIONS

The present study supports the safety of early tracheostomy among lung transplant recipients and highlights several potential benefits. Among appropriately selected patients, tracheostomy placement before postoperative day 8 may facilitate early discharge, lower costs, and reduced odds of posttransplant infection.

Imaging of Small Airways Disease

Bronchiolitis refers to a small airways disease and may be classified by etiology and histologic features. In cellular bronchiolitis inflammatory cells involve the small airway wall and peribronchiolar alveoli and manifest on CT as centrilobular nodules of solid or ground glass attenuation. Constrictive bronchiolitis refers to luminal narrowing by concentric fibrosis. Direct CT signs of small airway disease include centrilobular nodules and branching tree-in-bud opacities. An indirect sign is mosaic attenuation that may be exaggerated on expiratory CT and represent air trapping. Imaging findings can be combined with clinical and pathologic data to facilitate a more accurate diagnosis.

Creating superior lungs for transplantation with next-generation gene therapy during ex vivo lung perfusion

Engineering donor organs to better tolerate the harmful non-immunological and immunological responses inherently related to solid organ transplantation would improve transplant outcomes. Our enhanced knowledge of ischemia-reperfusion injury, alloimmune responses and pathological fibroproliferation after organ transplantation, and the advanced toolkit available for gene therapies, have brought this goal closer to clinical reality. Ex vivo organ perfusion has evolved rapidly especially in the field of lung transplantation, where clinicians routinely use ex vivo lung perfusion (EVLP) to confirm the quality of marginal donor lungs before transplantation, enabling safe transplantation of organs originally considered unusable. EVLP would also be an attractive platform to deliver gene therapies, as treatments could be administered to an isolated organ before transplantation, thereby providing a window for sophisticated organ engineering while minimizing off-target effects to the recipient. Here, we review the status of lung transplant first-generation gene therapies that focus on inducing transgene expression in the target cells. We also highlight recent advances in next-generation gene therapies, that enable gene editing and epigenetic engineering, that could be used to permanently change the donor organ genome and to induce widespread transcriptional gene expression modulation in the donor lung. In a future vision, dedicated organ repair and engineering centers will use gene editing and epigenetic engineering, to not only increase the donor organ pool, but to create superior organs that will function better and longer in the recipient.

Ventilatory capacity in CLAD is driven by dysfunctional airway structure

BACKGROUND

Chronic lung allograft dysfunction (CLAD) encompasses three main phenotypes: bronchiolitis obliterans syndrome (BOS), restrictive allograft syndrome (RAS) and a Mixed phenotype combining both pathologies. How the airway structure in its entirety is affected in these phenotypes is still poorly understood.

METHODS

A detailed analysis of airway morphometry was applied to gain insights on the effects of airway remodelling on the distribution of alveolar ventilation in end-stage CLAD. Ex vivo whole lung μCT and tissue-core μCT scanning of six control, six BOS, three RAS and three Mixed explant lung grafts (9 male, 9 female, 2014-2021, Leuven, Belgium) were used for digital airway reconstruction and calculation of airway dimensions in relation to luminal obstructions.

FINDINGS

BOS and Mixed explants demonstrated airway obstructions of proximal bronchioles (starting at generation five), while RAS explants particularly had airway obstructions in the most distal bronchioles (generation >12). In BOS and Mixed explants 76% and 84% of bronchioles were obstructed, respectively, while this was 22% in RAS. Bronchiolar obstructions were mainly caused by lymphocytic inflammation of the airway wall or fibrotic remodelling, i.e. constrictive bronchiolitis. Proximal bronchiolectasis and imbalance in distal lung ventilation were present in all CLAD phenotypes and explain poor lung function and deterioration of specific lung function parameters.

INTERPRETATION

Alterations in the structure of conducting bronchioles revealed CLAD to affect alveolar ventilatory distribution in a regional fashion. The significance of various obstructions, particularly those associated with mucus, is highlighted.

FUNDING

This research was funded with the National research fund Flanders (G060322N), received by R.V.

Thoracic organ transplantation and pregnancy outcomes: systematic review and meta-analysis

PURPOSE

Pre-conceptual comorbidities, an inherent risk of graft loss, rejection during pregnancy, and the postpartum period in women with thoracic lung transplant may predispose them to increased risk of adverse feto-maternal outcomes. The study aimed to systematically analyze and assess the risk of adverse pregnancy outcomes in women with thoracic organ transplant.

METHODS

MEDLINE, EMBASE, and Cochrane library were searched for publication between January 1990 and June 2020. Risk of bias was assessed using Joanna Briggs critical appraisal tool for case series. The primary outcomes included maternal mortality and pregnancy loss. The secondary outcomes were maternal complications, neonatal complications, and adverse birth outcomes. The analysis was performed using the DerSimonian-Laird random effects model.

RESULTS

Eleven studies captured data from 275 parturient with thoracic organ transplant describing 400 pregnancies. The primary outcomes included maternal mortality {pooled incidence (95% confidence interval) 4.2 (2.5-7.1) at 1 year and 19.5 (15.3-24.5) during follow-up}. Pooled estimates yielded 10.1% (5.6-17.5) and 21.8% (10.9-38.8) risk of rejection and graft dysfunction during and after pregnancy, respectively. Although 67% (60.2-73.2) of pregnancies resulted in live birth, total pregnancy loss and neonatal death occurred in 33.5% (26.7-40.9) and 2.8% (1.4-5.6), respectively. Prematurity and low birth weight were reported in 45.1% (38.5-51.9) and 42.7% (32.8-53.2), respectively.

CONCLUSIONS

Despite pregnancies resulting in nearly 2/3rd of live births, high incidence of pregnancy loss, prematurity and low birth weight remain a cause of concern. Focused pre-conceptual counseling to avoid unplanned pregnancy, especially in women with transplant-related organ dysfunctions and complications, is vital to improve pregnancy outcomes.

PROSPERO NUMBER

CRD42020164020.

Extracellular Vesicles in Transplantation: Friend or Foe

The long-term function of transplanted organs, even under immunosuppression, is hindered by rejection, especially chronic rejection. Chronic rejection occurs more frequently after lung transplantation, termed chronic lung allograft dysfunction (CLAD), than after transplantation of other solid organs. Pulmonary infection is a known risk factor for CLAD, as transplanted lungs are constantly exposed to the external environment; however, the mechanisms by which respiratory infections lead to CLAD are poorly understood. The role of extracellular vesicles (EVs) in transplantation remains largely unknown. Current evidence suggests that EVs released from transplanted organs can serve as friend and foe. EVs carry not only major histocompatibility complex antigens but also tissue-restricted self-antigens and various transcription factors, costimulatory molecules, and microRNAs capable of regulating alloimmune responses. EVs play an important role in antigen presentation by direct, indirect, and semidirect pathways in which CD8 and CD4 cells can be activated. During viral infections, exosomes (small EVs <200 nm in diameter) can express viral antigens and regulate immune responses. Circulating exosomes may also be a viable biomarker for other diseases and rejection after organ transplantation. Bioengineering the surface of exosomes has been proposed as a tool for targeted delivery of drugs and personalized medicine. This review focuses on recent studies demonstrating the role of EVs with a focus on exosomes and their dual role (immune activation or tolerance induction) after organ transplantation, more specifically, lung transplantation.

Weight, CYP3A5 Genotype, and Voriconazole Co-administration Influence Tacrolimus Initial Dosage in Pediatric Lung Transplantation Recipients with Low Hematocrit based on a Simulation Model

OBJECTIVE

The method of administering the initial doses of tacrolimus in recipients of pediatric lung transplantation, especially in patients with low hematocrit, is not clear. The present study aims to explore whether weight, CYP3A5 genotype, and voriconazole co-administration influence tacrolimus initial dosage in recipients of pediatric lung transplantation with low hematocrit based on safety and efficacy using a simulation model.

METHODS

The present study utilized the tacrolimus population pharmacokinetic model, which was employed in lung transplantation recipients with low hematocrit.

RESULTS

For pediatric lung transplantation recipients not carrying CYP3A5*1 and without voriconazole, the recommended tacrolimus doses for weights of 10-13, 13-19, 19-22, 22-35, 35-38, and 38-40 kg are 0.03, 0.04, 0.05, 0.06, 0.07, and 0.08 mg/kg/day, which are split into two doses, respectively. For pediatric lung transplantation recipients carrying CYP3A5*1 and without voriconazole, the recommended tacrolimus doses for weights of 10-18, 18-30, and 30-40 kg are 0.06, 0.08, 0.11 mg/kg/day, which are split into two doses, respectively. For pediatric lung transplantation recipients not carrying CYP3A5*1 and with voriconazole, the recommended tacrolimus doses for weights of 10-20 and 20-40 kg are 0.02 and 0.03 mg/kg/day, which are split into two doses, respectively. For pediatric lung transplantation recipients carrying CYP3A5*1 and with voriconazole, the recommended tacrolimus doses for weights of 10-20, 20-33, and 33-40 kg are 0.03, 0.04, and 0.05 mg/kg/day, which are split into two doses, respectively.

CONCLUSION

The present study is the first to recommend the initial dosages of tacrolimus in recipients of pediatric lung transplantation with low hematocrit using a simulation model.

Immune responses of lung transplant recipients against SARS-CoV-2 and common respiratory coronaviruses: Evidence for pre-existing cross-reactive immunity

Humoral and cellular immune responses to SARS-CoV-2 and other coronaviruses in lung transplant recipients are unknown. We measured antibodies and T cell responses against the SARS-CoV-2 spike S2 and nucleocapsid antigens and spike antigens from common respiratory coronaviruses (229E, NL63, OC43, and HKU1) after vaccination or infection of LTxRs. 148 LTxRs from single center were included in this study: 98 after vaccination and 50 following SARS-CoV-2 infection. Antibodies were quantified by enzyme-linked immunosorbent assay. The frequency of T cells secreting IL2, IL4, IL10, IL17, TNFα, and IFNγ were enumerated by enzyme-linked immunospot assay. Our results have shown the development of antibodies to SARS-CoV-2 spike protein in infected LTxRs (39/50) and vaccinated LTxRs (52/98). Vaccinated LTxRs had higher number of T cells producing TNFα but less cells producing IFNγ than infected LTxRs in response to the nucleocapsid antigen and other coronavirus spike antigens. We didn't find correlation between the development of antibodies and cellular immune responses against the SARS-CoV-2 spike protein after vaccination. Instead, LTxRs have pre-existing cellular immunity to common respiratory coronaviruses, leading to cross-reactive immunity against SARS-CoV-2 which likely will provide protection against SARS-Cov-2 infection.

Circulating donor-derived cell-free DNA as a marker for rejection after lung transplantation

Objective

Recently, circulating donor-derive cell free DNA (dd-cfDNA) has gained growing attention in the field of solid organ transplantation. The aim of the study was to analyze circulating dd-cfDNA levels in graft rejection, ACR and AMR separately for each rejection type compared with non-rejection, and assessed the diagnostic potential of dd-cfDNA levels in predicting graft rejection after lung transplantation.

Methods

A systematic search for relevant articles was conducted on Medline, Web of Science, China National Knowledge Infrastructure (CNKI), and Wanfang databases without restriction of languages. The search date ended on June 1, 2023. STATA software was used to analyze the difference between graft rejection, ACR, AMR and stable controls, and evaluate the diagnostic performance of circulating dd-cfDNA in detecting graft rejection.

Results

The results indicated that circulating dd-cfDNA levels in graft rejection, ACR, and AMR were significantly higher than non-rejection (graft rejection: SMD=1.78, 95% CI: 1.31-2.25, I2 = 88.6%, P< 0.001; ACR: SMD=1.03, 95% CI: 0.47-1.59, I2 = 89.0%, P < 0.001; AMR: SMD= 1.78, 95% CI: 1.20-2.35, I2 = 89.8%, P < 0.001). Circulating dd-cfDNA levels distinguished graft rejection from non-rejection with a pooled sensitivity of 0.87 (95% CI: 0.80-0.92) and a pooled specificity of 0.82 (95% CI: 0.76-0.86). The corresponding SROC yield an AUROC of 0.90 (95% CI: 0.87-0.93).

Conclusion

Circulating dd-cfDNA could be used as a non-invasive biomarker to distinguish the patients with graft rejection from normal stable controls.

Systematic Review Registration

https://www.crd.york.ac.uk/prospero/, identifier CRD42023440467.

Extracellular vesicles: a potential new player in antibody-mediated rejection in lung allograft recipients

Identification of recipients with pre-existing antibodies and cross-matching of recipient sera with donor lymphocytes have reduced the incidence of antibody-mediated rejection (AMR) after human lung transplantation. However, AMR is still common and requires not only immediate intervention but also has long-term consequences including an increased risk of chronic lung allograft dysfunction (CLAD). The mechanisms resulting in AMR remain largely unknown due to the variation in clinical and histopathological features among lung transplant recipients; however, several reports have demonstrated a strong association between the development of antibodies against mismatched donor human leucocyte antigens [donor-specific antibodies (DSAs)] and AMR. In addition, the development of antibodies against lung self-antigens (K alpha1 tubulin and collagen V) also plays a vital role in AMR pathogenesis, either alone or in combination with DSAs. In the current article, we will review the existing literature regarding the association of DSAs with AMR, along with clinical diagnostic features and current treatment options for AMR. We will also discuss the role of extracellular vesicles (EVs) in the immune-related pathogenesis of AMR, which can lead to CLAD.

Imaging in Lung Transplantation: Surgical Techniques and Complications

Lung transplant is an established treatment for patients with end-stage lung disease. As a result, there is increased demand for transplants. Despite improvements in pretransplant evaluation, surgical techniques, and postsurgical care, the average posttransplant life expectancy is only around 6.5 years. Early recognition of complications on imaging and treatment can improve survival. Knowledge of surgical techniques and imaging findings of surgical and nonsurgical complications is essential. This review covers surgical techniques and imaging appearance of postsurgical and nonsurgical complications, including allograft dysfunction, infections, neoplasms, and recurrence of primary lung disease.

Radiomics of spinal muscles: toward a radiological biomarker for allograft rejection in lung transplant

PURPOSE

To assess the role of muscle composition and radiomics in predicting allograft rejection in lung transplant.

MATERIAL AND METHODS

The last available HRCT before surgery of lung transplant candidates referring to our tertiary center from January 2010 to February 2020 was retrospectively examined. Only scans with B30 kernel reconstructions and 1 mm slice thickness were included. One radiologist segmented the spinal muscles of each patient at the level of the 11th dorsal vertebra by an open-source software. The same software was used to extract Hu values and 72 radiomic features of first and second order. Factor analysis was applied to select highly correlating features and then their prognostic value for allograft rejection was investigated by logistic regression analysis (level of significance p < 0.05). In case of significant results, the diagnostic value of the model was computed by ROC curves.

RESULTS

Overall 200 patients had a HRCT prior to the transplant but only 97 matched the inclusion criteria (29 women; mean age 50.4 ± 13 years old). Twenty-one patients showed allograft rejection. The following features were selected by the factor analysis: cluster prominence, Imc2, gray level non-uniformity normalized, median, kurtosis, gray level non-uniformity, and inverse variance. The radiomic-based model including also Hu demonstrated that only the feature Imc2 acts as a predictor of allograft rejection (p = 0.021). The model showed 76.6% accuracy and the Imc2 value of 0.19 demonstrated 81% sensitivity and 64.5% specificity in predicting lung transplant rejection.

CONCLUSION

The radiomic feature Imc2 demonstrated to be a predictor of allograft rejection in lung transplant.

Refractory Pseudomonas aeruginosa Bronchopulmonary Infection After Lung Transplantation for Common Variable Immunodeficiency Despite Maximal Treatment Including IgM/IgA-Enriched Immunoglobulins and Bacteriophage Therapy

Recipients transplanted for bronchiectasis in the context of a primary immune deficiency, such as common variable immunodeficiency, are at a high risk of severe infection in post-transplantation leading to poorer long-term outcomes than other transplant indications. In this report, we present a fatal case due to chronic Pseudomonas aeruginosa bronchopulmonary infection in a lung transplant recipient with common variable immunodeficiency despite successful eradication of an extensively drug-resistant (XDR) strain with IgM/IgA-enriched immunoglobulins and bacteriophage therapy. The fatal evolution despite a drastic adaptation of the immunosuppressive regimen and the maximal antibiotic therapy strategy raises the question of the contraindication of lung transplantation in such a context of primary immunodeficiency.

Pre-Lung transplant reflux testing demonstrates high prevalence of gastroesophageal reflux in cystic fibrosis and reduces chronic rejection risk

BACKGROUND

Gastroesophageal reflux (GER) has been associated with poor outcomes after lung transplantation for chronic lung disease, including increased risk of chronic rejection. GER is common in cystic fibrosis (CF), but factors influencing the likelihood of pre-transplant pH testing, and the impact of testing on clinical management and transplant outcomes in patients with CF are unknown.

AIM

To evaluate the role of pre-transplant reflux testing in the evaluation of lung transplant candidates with CF.

METHODS

This was a retrospective study from 2007-2019 at a tertiary medical center that included all patients with CF undergoing lung transplant. Patients with pre-transplant anti-reflux surgery were excluded. Baseline characteristics (age at transplantation, gender, race, body mass index), self-reported GER symptoms prior to transplantation, and pre-transplant cardiopulmonary testing results, were recorded. Reflux testing consisted of either 24-h pH- or combined multichannel intraluminal impedance and pH monitoring. Post-transplant care included a standard immunosuppressive regimen, and regular surveillance bronchoscopy and pulmonary spirometry in accordance with institutional practice as well as in symptomatic patients. The primary outcome of chronic lung allograft dysfunction (CLAD) was defined clinically and histologically per International Society of Heart and Lung Transplantation criteria. Statistical analysis was performed with Fisher's exact test to assess differences between cohorts, and time-to-event Cox proportional hazards modeling.

RESULTS

After applying inclusion and exclusion criteria, a total of 60 patients were included in the study. Among all CF patients, 41 (68.3%) completed reflux monitoring as part of pre-lung transplant evaluation. Objective evidence of pathologic reflux, defined as acid exposure time > 4%, was found in 24 subjects, representing 58% of the tested group. CF patients with pre-transplant reflux testing were older (35.8 vs 30.1 years, P = 0.01) and more commonly reported typical esophageal reflux symptoms (53.7% vs 26.3%, P = 0.06) compared to those without reflux testing. Other patient demographics and baseline cardiopulmonary function did not significantly differ between CF subjects with and without pre-transplant reflux testing. Patients with CF were less likely to undergo pre-transplant reflux testing compared to other pulmonary diagnoses (68% vs 85%, P = 0.003). There was a decreased risk of CLAD in patients with CF who underwent reflux testing compared to those who did not, after controlling for confounders (Cox Hazard Ratio 0.26; 95%CI: 0.08-0.92).

CONCLUSION

Pre-transplant reflux testing revealed high prevalence of pathologic reflux in CF patients and was associated with decreased risk of CLAD. Systematic reflux testing may enhance outcomes in this patient population.

Mesenchymal Stromal Cell Therapy in Lung Transplantation

Lung transplantation is often the only viable treatment option for a patient with end-stage lung disease. Lung transplant results have improved substantially over time, but ischemia-reperfusion injury, primary graft dysfunction, acute rejection, and chronic lung allograft dysfunction (CLAD) continue to be significant problems. Mesenchymal stromal cells (MSC) are pluripotent cells that have anti-inflammatory and protective paracrine effects and may be beneficial in solid organ transplantation. Here, we review the experimental studies where MSCs have been used to protect the donor lung against ischemia-reperfusion injury and alloimmune responses, as well as the experimental and clinical studies using MSCs to prevent or treat CLAD. In addition, we outline ex vivo lung perfusion (EVLP) as an optimal platform for donor lung MSC delivery, as well as how the therapeutic potential of MSCs could be further leveraged with genetic engineering.

Application of plasma donor-derived cell free DNA for lung allograft rejection diagnosis in lung transplant recipients

BACKGROUND

Donor-derived cell-free DNA (dd-cfDNA) has been applied to monitor acute rejection (AR) in kidney and heart transplantation. This study was aimed to investigate the application of dd-cfDNA levels in the diagnosis of AR and chronic lung allograft dysfunction (CLAD) among the lung transplantation recipients (LTRs).

METHODS

One hundred and seventy LTRs were enrolled at the First Affiliated Hospital of Guangzhou Medical University between 1 June 2015 and 30 March 2021. Patients were divided into 4 groups: stable group, AR group, infection group and CLAD group. The level of dd-cfDNA was analyzed using target region sequencing and the performance characteristics of dd-cfDNA for diagnosis of AR and CLAD were determined, respectively.

RESULTS

Kruskal-Wallis test showed that there were some significant differences in the level of dd-cfDNA (%) among the 4 groups, with p < 0.001. Among them, the level of dd-cfDNA (%) was highest (median 2.17, IQR [1.40-3.82]) in AR group, and higher in CLAD group (median 1.07, IQR [0.98-1.31]), but lower in infection group (median 0.71, IQR [0.57-1.07]) and lowest in stable group (median 0.71, IQR [0.61-0.84]). AUC-ROC curve analysis showed that the threshold of dd-cfDNA for AR was 1.17%, with sensitivity being 89.19% and specificity being 86.47%, and the optimal threshold of 0.89% was determined of CLAD, with sensitivity being 95.00% and specificity of 76.99%.

CONCLUSIONS

Plasma dd-cfDNA could be a useful tool for the assessment of lung allograft rejection, including AR and CLAD, and holds promise as a noninvasive biomarker for "allograft injury" in both acute and chronic rejection following lung transplantation.

Revisiting transplant immunology through the lens of single-cell technologies

Solid organ transplantation (SOT) is the standard of care for end-stage organ disease. The most frequent complication of SOT involves allograft rejection, which may occur via T cell- and/or antibody-mediated mechanisms. Diagnosis of rejection in the clinical setting requires an invasive biopsy as there are currently no reliable biomarkers to detect rejection episodes. Likewise, it is virtually impossible to identify patients who exhibit operational tolerance and may be candidates for reduced or complete withdrawal of immunosuppression. Emerging single-cell technologies, including cytometry by time-of-flight (CyTOF), imaging mass cytometry, and single-cell RNA sequencing, represent a new opportunity for deep characterization of pathogenic immune populations involved in both allograft rejection and tolerance in clinical samples. These techniques enable examination of both individual cellular phenotypes and cell-to-cell interactions, ultimately providing new insights into the complex pathophysiology of allograft rejection. However, working with these large, highly dimensional datasets requires expertise in advanced data processing and analysis using computational biology techniques. Machine learning algorithms represent an optimal strategy to analyze and create predictive models using these complex datasets and will likely be essential for future clinical application of patient level results based on single-cell data. Herein, we review the existing literature on single-cell techniques in the context of SOT.

Adverse Events Associated with Universal versus Targeted Antifungal Prophylaxis among Lung Transplant Recipients-A Nationwide Cohort Study 2010-2019

Background: Invasive fungal infections in lung transplant (LTX) recipients cause substantial morbidity, but the best strategy for prevention has not yet been determined. We evaluated adherence to and rates of adverse events of universal versus targeted prophylaxis. Methods: All LTX recipients in the Danish National LTX Centre (2010−2019) were included. Before July 2016, universal voriconazole prophylaxis was used. After July 2016, only high-risk patients received targeted prophylaxis with posaconazole and inhaled amphotericin B. Proportions of triazole discontinuation, side-effects, off-target calcineurin-inhibitor (CNI) levels, and acute rejection were compared between the two periods. Results: Universal and targeted prophylaxis was initiated in 183/193 and 6/102 patients, respectively. Only 37% completed > 9 of the intended 12 weeks of voriconazole; 72% of discontinuations were due to hepatotoxicity. In the universal vs. targeted prophylaxis period, 89% vs. 72% (p < 0.001) patients had low CNI episodes, and 37% vs. 1% (p < 0.001) of these were associated with discontinuation of triazole; 40% vs. 14% (p < 0.001) had acute rejection; and 23% vs. 3% (p < 0.001) had acute rejection associated with low CNI episodes. Conclusions: Universal voriconazole prophylaxis was associated with high rates of discontinuation, mainly caused by hepatotoxicity. In comparison to the targeted posaconazole period, more patients had low CNI levels and acute rejection in the universal voriconazole period.

Personalized risk predictor for acute cellular rejection in lung transplant using soluble CD31

We evaluated the contribution of artificial intelligence in predicting the risk of acute cellular rejection (ACR) using early plasma levels of soluble CD31 (sCD31) in combination with recipient haematosis, which was measured by the ratio of arterial oxygen partial pressure to fractional oxygen inspired (PaO₂/FiO₂) and respiratory SOFA (Sequential Organ Failure Assessment) within 3 days of lung transplantation (LTx). CD31 is expressed on endothelial cells, leukocytes and platelets and acts as a "peace-maker" at the blood/vessel interface. Upon nonspecific activation, CD31 can be cleaved, released, and detected in the plasma (sCD31). The study included 40 lung transplant recipients, seven (17.5%) of whom experienced ACR. We modelled the plasma levels of sCD31 as a nonlinear dependent variable of the PaO₂/FiO₂ and respiratory SOFA over time using multivariate and multimodal models. A deep convolutional network classified the time series models of each individual associated with the risk of ACR to each individual in the cohort.

Characterization of chronic lung allograft dysfunction phenotypes using spectral and intrabreath oscillometry

Background: Chronic lung allograft dysfunction (CLAD) is the major cause of death beyond 2 years after lung transplantation and develops in 50% of all patients by 5 years post-transplant. CLAD is diagnosed on the basis of a sustained drop of 20% for at least 3 months in the forced expiratory volume (FEV₁), compared to the best baseline value achieved post-transplant. CLAD presents as two main phenotypes: bronchiolitis obliterans syndrome (BOS) is more common and has better prognosis than restrictive allograft syndrome (RAS). Respiratory oscillometry is a different modality of lung function testing that is highly sensitive to lung mechanics. The current study investigated whether spectral and intrabreath oscillometry can differentiate between CLAD-free, BOS- and RAS-CLAD at CLAD onset, i.e., at the time of the initial 20% drop in the FEV₁.

Methods: A retrospective, cross-sectional analysis of 263 double lung transplant recipients who underwent paired testing with oscillometry and spirometry at the Toronto General Pulmonary Function Laboratory from 2017 to 2022 was conducted. All pulmonary function testing and CLAD diagnostics were performed following international guidelines. Statistical analysis was conducted using multiple comparisons.

Findings: The RAS (n = 6) spectral oscillometry pattern differs from CLAD-free (n = 225) by right-ward shift of reactance curve similar to idiopathic pulmonary fibrosis whereas BOS (n = 32) has a pattern similar to obstructive lung disease. Significant differences were found in most spectral and intrabreath parameters between BOS, RAS, and time-matched CLAD-free patients. Post-hoc analysis revealed these differences were primarily driven by BOS instead of RAS. While no differences were found between CLAD-free and RAS patients with regards to spectral oscillometry, the intrabreath metric of reactance at end-inspiration (XeI) was significantly different (p < 0.05). BOS and RAS were differentiated by spectral oscillometry measure R5, and intrabreath resistance at end expiration, ReE (p < 0.05 for both).

Conclusion: Both spectral and intrabreath oscillometry can differentiate BOS-CLAD from CLAD-free states while intrabreath oscillometry, specifically XeI, can uniquely distinguish RAS-CLAD from CLAD-free. Spectral and intrabreath oscillometry offer complementary information regarding lung mechanics in CLAD patients to help distinguish the two phenotypes and could prove useful in prognostication.

COVID-Related Chronic Allograft Dysfunction in Lung Transplant Recipients: Long-Term Follow-up Results from Infections Occurring in the Pre-vaccination Era

Introduction: We report on characteristics and lung function outcomes among lung transplant recipients (LTRs) after COVID-19 with infections occurring in the first year of the coronavirus pandemic prior to introduction of the vaccines. Methods: This was a retrospective study of 18 LTRs who tested positive for SARS-CoV-2 between 1 February 2020 and 1 March 2021. The mean age was 49.9 (22–68) years; 12 patients (67%) were male. Two patients died due to severe COVID-19. Results: During the study period, there were 18 lung transplant recipients with a community-acquired SARS-CoV-2 infection. In this cohort, seven had mild, nine had moderate, and two had severe COVID-19. All patients with mild and moderate COVID-19 survived, but the two patients with severe COVID-19 died in the intensive care unit while intubated and on mechanical ventilation. Most patients with moderate COVID-19 showed a permanent lung function decrease that did not improve after 12 months. Conclusion: A majority of LTRs in the current cohort did not experience an alteration in the trajectory of FEV1 evolution after developing SARS-CoV-2 infection. However, in the patients with moderate COVID-19, most patients had a decline in the FEV1 that was present after 1 month after recovery and did not improve or even deteriorated further after 12 months. In LTRs, COVID-19 can have long-lasting effects on pulmonary function. Treatment strategies that influence this trajectory are needed.

Basiliximab vs. Antithymocyte Globulin as Initial Induction Therapy for Lung Transplantation: A National Two Years Review

Basiliximab (BAS) is an interleukin-2 monoclonal antibody initially used as induction therapy after liver and kidney transplantation. BAS use after lung transplantation (LTx) has supplanted antithymocyte globulin (ATG) as the main induction immunosuppression over the years, but few studies have compared them. In this study, we aimed to compare the efficacy and safety between BAS and ATG in LTx. We performed a retrospective analysis of all LTx done in Portugal between January 2016 and December 2019. Three groups were made according to the initial induction status: BAS, ATG or no induction (NI). The occurrences of cytomegalovirus (CMV) infection, pneumonia, side effects, primary graft dysfunction (PGD), acute rejection, chronic allograft disfunction (CLAD) and death episodes were assessed during two years after LTx. A total of 124 patients were divided in 3 groups: 61 (49.2%) BAS; 43 (34.7%) ATG; 20 (16.1%) NI. The incidences of pneumonia and CMV were similar between induction groups. Additionally, there was no difference between the induction groups in PGD, acute rejection, CLAD, deaths and two-year survival. Side effects were reported only in ATG group (n = 20; 46.5%). In our study, BAS had a better safety profile than ATG in LTx with a similar efficacy.

Lung transplantation and severe coronary artery disease: results from a single-centre experience

OBJECTIVES

The management of severe coronary artery disease at the time of lung transplantation remains a challenge. We analyzed the short- and long-term-outcomes of lung transplant recipients with severe coronary artery disease.

METHODS

Records of adult patients transplanted at our institution between April 2010 and February 2021 were retrospectively reviewed. Severe coronary artery disease was defined by coronary stenosis ≥70% (main stem ≥50%) at the coronary angiography performed before or at the time of listing. Patient characteristics, perioperative- and long-term-outcomes were compared between patients with and without severe coronary artery disease.

RESULTS

Among 896 lung-transplanted patients who had undergone a coronary angiography before transplantation, 77 (8.5%) showed severe coronary artery disease, the remaining 819 (91.5%) did not. Patients with severe coronary artery disease were older (p < 0.0001), more often male (p < 0.0001) and were transplanted more often for pulmonary fibrosis (p = 0.0007). The median (interquartile range) follow-up was 46 (20-76) months. At the Cox multivariable analysis severe coronary artery disease was not associated with mortality. Patients with pretransplant percutaneous transluminal coronary angioplasty and patients with coronary artery bypass graft surgery concomitant to transplantation had equivalent survival compared to patients without severe coronary artery disease (p = 0.513, p = 0.556).

CONCLUSIONS

Severe coronary artery disease was not associated with decreased survival after lung transplantation. Concomitant coronary artery bypass graft surgery and pretransplant percutaneous transluminal coronary angioplasty can be used for revascularization.

Safety of Inhaled Amphotericin B Lipid Complex as Antifungal Prophylaxis in Lung Transplant Recipients

Inhaled formulations of amphotericin B are the most widely used antifungal prophylactic agents in lung transplant recipients, yet there are limited data on their safety. We performed a single-center retrospective cohort study of 603 consecutive patients who underwent lung transplantation between 2012 and 2017 and received antifungal prophylaxis with inhaled amphotericin B lipid complex (iABLC) from the day of transplantation until hospital discharge. Of 603 patients, 600 (99.5%) received ≥1 dose of iABLC, and 544 (90.2%) completed the recommended prophylactic course. In total, 4,128 iABLC doses (median, 5; range, 1 to 48 per patient) were administered; 24 patients received >3 months of therapy. Only one (0.2%) patient discontinued therapy due to a drug-attributable adverse event. During the first posttransplant year, 80 (13.3%) patients died (median time to death, 171 days; interquartile range [IQR], 80 to 272 days), and 3,352 (median, 6 per patient) lung biopsies were performed; 414 (68.7%) patients developed biopsy-proven acute cellular rejection. One-year adverse events in our cohort of lung transplant recipients treated with iABLC during transplant hospitalization matched national outcomes for rejection, graft loss, and death. iABLC is a safe and well-tolerated antifungal prophylactic agent in lung transplant recipients.

Acute rejection and post lung transplant surveillance

Purpose

The purpose of this review is to summarize the current evidence on the evaluation and treatment of acute rejection after lung transplantation.

Results

Despite significant progress in the field of transplant immunology, acute rejection remains a frequent complication after transplantation. Almost 30% of lung transplant recipients experience at least one episode of acute cellular rejection (ACR) during the first year after transplant. Acute cellular rejection, lymphocytic bronchiolitis, and antibody-mediated rejection (AMR) are all risk factors for the subsequent development of chronic lung allograft dysfunction (CLAD). Acute cellular rejection and lymphocytic bronchiolitis have well-defined histopathologic diagnostic criteria and grading. The diagnosis of antibody-mediated rejection after lung transplantation requires a multidisciplinary approach. Antibody-mediated rejection may cause acute allograft failure.

Conclusions

Acute rejection is a risk factor for development of chronic rejection. Further investigations are required to better define risk factors, surveillance strategies, and optimal management strategies for acute allograft rejection.

Family-building and parenting considerations for people with cystic fibrosis

As people with cystic fibrosis (CF) live longer and healthier lives, increasing numbers are considering the full range of reproductive options for their futures, including parenthood, pregnancy, or pregnancy prevention. As the face of CF changes, the CF care model must adapt to meet the reproductive health needs of both parents and nonparents with CF. This article summarizes the reproductive goals and family-building concerns faced by people with CF, including fertility, pregnancy, and alternative paths to parenthood, the impact of parenthood on mental and physical health, and important future research.

Postoperative Management of Lung Transplant Recipients in the Intensive Care Unit

The number of lung transplantations is progressively increasing worldwide, providing new challenges to interprofessional teams and the intensive care units. The outcome of lung transplantation recipients is critically affected by a complex interplay of particular pathophysiologic conditions and risk factors, knowledge of which is fundamental to appropriately manage these patients during the early postoperative course. As high-grade evidence-based guidelines are not available, the authors aimed to provide an updated review of the postoperative management of lung transplantation recipients in the intensive care unit, which addresses six main areas: (1) management of mechanical ventilation, (2) fluid and hemodynamic management, (3) immunosuppressive therapies, (4) prevention and management of neurologic complications, (5) antimicrobial therapy, and (6) management of nutritional support and abdominal complications. The integrated care provided by a dedicated multidisciplinary team is key to optimize the complex postoperative management of lung transplantation recipients in the intensive care unit.

Pregnancy in cystic fibrosis: Review of the literature and expert recommendations

Cystic fibrosis (CF) was historically a disease largely afflicting children. Due to therapeutic advancements, there are now more adults with CF than children. In the past decade, medications including Cystic Fibrosis Transmembrane conductance Regulator (CFTR) modulators became available that treat the underlying cause of CF and are dramatically improving lung function as well as quality and quantity of life for people with CF. As a result, more women with CF are becoming pregnant. We gathered a panel of experts in CF care, family planning, high risk obstetrics, nutrition, genetics and women with CF to review current literature on pregnancies and to provide care recommendations for this unique population.

Liposomes Loaded with Everolimus and Coated with Hyaluronic Acid: A Promising Approach for Lung Fibrosis

Chronic lung allograft dysfunction (CLAD) and interstitial lung disease associated with collagen tissue diseases (CTD-ILD) are two end-stage lung disorders in which different chronic triggers induce activation of myo-/fibroblasts (LFs). Everolimus, an mTOR inhibitor, can be adopted as a potential strategy for CLAD and CTD-ILD, however it exerts important side effects. This study aims to exploit nanomedicine to reduce everolimus side effects encapsulating it inside liposomes targeted against LFs, expressing a high rate of CD44. PEGylated liposomes were modified with high molecular weight hyaluronic acid and loaded with everolimus (PEG-LIP(ev)-HA400kDa). Liposomes were tested by in vitro experiments using LFs derived from broncholveolar lavage (BAL) of patients affected by CLAD and CTD-ILD, and on alveolar macrophages (AM) and lymphocytes isolated, respectively, from BAL and peripheral blood. PEG-LIP-HA400kDa demonstrated to be specific for LFs, but not for CD44-negative cells, and after loading everolimus, PEG-LIP(ev)-HA400kDa were able to arrest cell cycle arrest and to decrease phospho-mTOR level. PEG-LIP(ev)-HA400kDa showed anti-inflammatory effect on immune cells. This study opens the possibility to use everolimus in lung fibrotic diseases, demonstrating that our lipids-based vehicles can vehicle everolimus inside cells exerting the same drug molecular effect, not only in LFs, but also in immune cells.

Calcineurin Inhibitor-Based Maintenance Immunosuppression in Lung Transplant Recipients: Optimal Serum Levels for Managing Acute Rejection and Renal Function

BACKGROUND

Although effective for curtailing alloimmune responses, calcineurin inhibitors (CNIs) have an adverse-effect profile that includes nephrotoxicity. In lung transplant (LTx) recipients, the optimal serum levels of the CNI tacrolimus necessary to control alloimmune responses and minimize nephrotoxicity are unknown.

METHODS

This retrospective, single-center study reviewed tacrolimus whole blood trough levels (BTLs), grades of acute cellular rejection (ACR), acute rejection scores, and creatinine clearance (CrCl) obtained in LTx recipients within the first year after their transplant procedure. Comparisons were made between the first 90 days post LTx (when tacrolimus BTLs were maintained >10 µg/L) and the remainder of the post-LTX year (when BTLs were <10 µg/L).

RESULTS

Despite tacrolimus mean BTLs being higher during the first 90 days post LTx compared with the remainder of the first post-LTx year (10.4 ± 0.3 µg/L vs 9.5 ± 0.3 µg/L, P < .0001) there was no association with lower grades of ACR (P = .24). The intensity of ACR (as determined by acute rejection scores) did not correlate with tacrolimus mean BTLs at any time during the first posttransplant year (P = .79). During the first 90 days post LTx there was a significant decline in CrCl and a correlation between increasing tacrolimus mean BTLs and declining CrCl (r = -0.26, P = .03); a correlation that was not observed during the remainder of the year (r = -0.09, P = .52).

CONCLUSIONS

In LTx recipients, maintaining BTLs of the CNI tacrolimus >10µg/L did not result in superior control of acute rejection responses but was associated with declining renal function.

Early postoperative complications in lung transplant recipients

Lung transplantation has become an established therapy for end-stage lung diseases. Early postoperative complications can impact immediate, mid-term, and long-term outcomes. Appropriate management, prevention, and early detection of these early postoperative complications can improve the overall transplant course. In this review, we highlight the incidence, detection, and management of these early postoperative complications in lung transplant recipients.

Lung Transplantation and the Era of the Sensitized Patient

Long term outcomes in lung transplant are limited by the development of chronic lung allograft dysfunction (CLAD). Within the past several decades, antibody-mediated rejection (AMR) has been recognized as a risk factor for CLAD. The presence of HLA antibodies in lung transplant candidates, "sensitized patients" may predispose patients to AMR, CLAD, and higher mortality after transplant. This review will discuss issues surrounding the sensitized patient, including mechanisms of sensitization, implications within lung transplant, and management strategies.

Osteopontin and Transplantation: Where Are We Now?

Organ transplantation represents the optimal therapeutic tool for patients with end-stage organ failure. Hematopoietic stem cell transplantation (HSCT) is likewise an effective therapy for a wide range of malignant and non-malignant diseases. Better understanding of transplantation immunology and the use of multi-modal immunosuppression protocols, can decrease the risk of graft failure and graft-versus-host disease (GVHD) after HSCT. Nevertheless, a major challenge of modern transplantology still seems to be finding non-invasive biomarkers for recipients selection, monitoring of allograft function, and diagnosis of rejection. Since proinflammatory cytokine osteopontin (OPN) is closely involved in regulating both adaptive and innate immune responses, as well as the pathogenesis of inflammatory and autoimmune diseases, it is likely to play an important role in organ and HSC transplantation. This review is to summarize recent advances in our knowledge about OPN function in the kidney, heart, liver, lung, and HSC transplantation. Most studies found that elevated OPN is associated with poorer graft function in kidney, heart, liver and lung recipients. Moreover, some reports suggested that this protein can play role in GVHD pathogenesis. However, due to relatively small number of similar studies, as well as some inconclusive results, future investigation in this field is needed to verify if OPN can serve as a biomarker of organ and HSC transplantation. The knowledge about such markers will promote our understanding of the mechanisms underlying graft dysfunction and posttransplant mortality. In addition, such knowledge may be helpful in the development of new treatment strategies and identification of recipients with increased risk of allograft failure.

Antibody-Mediated Rejection Management Following Lung Transplantation

BACKGROUND

Although antibody-mediated rejection (AMR) is described in other solid organ transplant populations, the literature describing the management following lung transplantation is limited.

OBJECTIVE

The purpose of this study is to evaluate the management strategies of AMR in lung transplant recipients.

METHODS

This single-center, retrospective study described the management of AMR in adult lung transplant recipients who received treatment with rabbit antithymocyte globulin, bortezomib, rituximab, intravenous immune globulin (IVIG), and/or plasmapheresis between September 2015 and June 2019.

RESULTS

A total of 270 medication orders for 55 patient admissions were included in the primary outcome analysis. The most commonly used regimen consisted of IVIG, plasmapheresis, and rituximab (49.1%; n = 27), followed by IVIG and plasmapheresis alone (27.3%, n = 15). A total of 51 patients (93%) received plasmapheresis as part of their AMR treatment, with a median of 4 [3, 5] sessions per encounter; 86% of patients with positive donor-specific antibodies (DSAs) had a reduction in DSAs following AMR treatment. Overall, 23.5% of patients had noted allograft failure or need for retransplantation. A total of 10 patients died during the AMR treatment hospital admission, and an additional 11 patients died within 1 year of the initial encounter.

CONCLUSION AND RELEVANCE

This represents the largest report describing management strategies of AMR in lung transplant recipients. Although practice varied, the most commonly used regimen consisted of plasmapheresis, IVIG, and rituximab.

A Comparison of Methylprednisolone and Dexamethasone in Intensive Care Patients With COVID-19

OBJECTIVES

This study retrospectively compares the effectiveness of methylprednisolone to dexamethasone in patients with severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2 or COVID-19) requiring intensive care.

DESIGN

This is an institutional review board approved cohort study in patients with COVID-19 requiring intensive care unit (ICU) admission. Patients admitted and requiring oxygen supplementation were treated with no steroids, methylprednisolone, or dexamethasone.

SETTING

This study takes place in the ICU's at a large, tertiary, public teaching hospital serving a primarily low-income community in urban Los Angeles.

PATIENTS

All eligible patients admitted to the ICU for COVID-19 respiratory failure from March 1 to July 31, 2020 were included in this study.

INTERVENTIONS

A total of 262 patients were grouped as receiving usual care (n = 75), methylprednisolone dosed at least at 1mg/kg/day for ≥ 3 days (n = 104), or dexamethasone dosed at least at 6 mg for ≥7 days (n = 83).

MEASUREMENTS AND MAIN RESULTS

All-cause mortality within 50 days of initial corticosteroid treatment as compared to usual care was calculated. The mortality effect was then stratified based on levels of respiratory support received by the patient. In this cohort of 262 patients with severe COVID-19, all-cause mortalities in the usual care, methylprednisolone, and dexamethasone groups were 41.3%, 16.4% and 26.5% at 50 days (P < 0.01) respectively. In patients requiring mechanical ventilation, mortality was 42% lower in the methylprednisolone group than in the dexamethasone group (hazard ratio 0.48, 95% CI: 0.235-0.956, P = 0.0385).

CONCLUSIONS

In COVID-19 patients requiring mechanical ventilation, sufficiently dosed methylprednisolone can lead to a further decreased mortality as compared to dexamethasone.

A review of imlifidase in solid organ transplantation

INTRODUCTION

Sensitization to human leukocyte antigens has long posed an obstacle to organ transplantation. With desensitization protocol refinement, new drug development, and organ allocation policy changes, access to transplant for sensitized patients has never been greater. Yet in spite of these advances the problem of donor-specific antibody remains incompletely solved, and many patients remain poorly served by the therapies that do exist. Area covered: Imlifidase is a new drug with a mechanism of action that enables it to transiently yet efficiently eliminate donor-specific antibody over a much more rapid time course than any heretofore existing therapy. This unique property suggests that imlifidase may have far-reaching potential for patients in whom donor-specific antibodies may preclude successful transplantation. Below follows a review of the clinical experience with imlifidase to date as well as a discussion of the transplant applications that eagerly await the availability of this novel agent. Expert opinion: Imlifidase is a first-in-class pharmaceutical agent that safely and efficiently cleaves IgG, and holds promise to be a game-changer for sensitized patients in need of lifesaving organ transplants.

Free Airway C4d after Lung Transplantation - A Quantitative Analysis of Bronchoalveolar Lavage Fluid

In recent years, the utility of vascular complement factor 4d (C4d) deposition as diagnostic tool for antibody mediated rejection (AMR) after lung transplantation, has become a controversial issue. We aimed to pinpoint the problematic nature of C4d as biomarker with a simple experiment. We quantified C4d in broncho-alveolar lavage (BAL) of lung transplant patients with diverse post-transplant complications in 3 different settings of clinically clear cases of: 1/ chronic lung allograft dysfunction (CLAD); 2/ acute complications acute rejection (AR), lymphocytic bronchiolitis (LB), antibody-mediated rejection (AMR) and respiratory infection (INF); 3/ patients with parallel C4d immunostaining and Anti-HLA. All groups were compared to BAL of stable patients. C4d was measured via standard ELISA. C4d was increased in CLAD, predominantly in RAS (p = 0.0026) but not in BOS (p = 0.89). C4d was increased in all acute events, AR (p = 0.0025), LB (p < 0.0001), AMR (p = 0.0034), infections (p < 0.0001). In patients with parallel C4d immunostaining and serum HLA antibodies, C4d was increased in C4d-/HLA- (p = 0.0011); C4d-/HLA+ (p = 0.013); HLA+/C4d + (p = 0.0081). A correlation of systemic C-reactive protein (CRP) with C4d was found in all patients (r = 0.49; p < 0.0001). We hypothesize that free C4d in BAL may only be representative of a general immune response in the transplanted lung.

Early acute rejection after lung transplantation mimicking viral pneumonia in the middle of COVID-19 pandemic: A case report

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An atypical clinical presentation of early antibody-mediated rejection in COVID era.

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The radiological features mimicked SARS-CoV2 pneumonia, but tests were negative.

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This is the first report of lung transplantation in the COVID era in Europe.

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Decide whether to keep lung transplantation programmes open in a COVID Hospital.

Introduction

In addition to morbidity and mortality rate per se, COVID-19 outbreak leads to potential ‘side effects’, which are difficult to evaluate and predict. Lung transplantation is a consolidated treatment for end-stage chronic lung disease requiring significantly demanding management. Deciding whether to keep transplant programmes open during an epidemic of this size is not easy, as immunosuppressed subjects face the risk of infection and related mortality. Additionally, there is a chance for the patient’s standard care process to be compromised.

Presentation of case

We report the case of a patient undergoing bilateral lung transplantation during the explosion of COVID-19 epidemic in Lombardy; he died from definite early acute antibody-mediated rejection, clinically (persistent high fever, unresponsive to treatment) and radiologically mimicking viral pneumonia but persistently negative for SARS-CoV-2.

Discussion

The diagnosis was difficult given this atypical presentation, confounded by global scenario. Grafts were procured from a donation after circulatory death donor in an uncontrolled setting and a donor-recipient transmission was possible. Our institute became a COVID-Hospital right during the first post-transplantation days. Radiological imaging had the same features of SARS-CoV-2 pneumonia.

Conclusions

This is the first report of lung transplantation of the COVID-19 era in Europe. Our extremely fragile patient was COVID-19 free up to the end. Donor-recipient transmission is conceivable, but the risk should be assessed with respect to waiting list mortality. Ultimately, treating COVID-19 patients can be a resource-consuming activity but we decided to keep our centre open.

Screening and identification of key regulatory connections and immune cell infiltration characteristics for lung transplant rejection using mucosal biopsies

This study aimed to explore key regulatory connections underlying lung transplant rejection. The differentially expressed genes (DEGs) between rejection and stable lung transplantation (LTx) samples were screened using R package limma, followed by functional enrichment analysis and protein-protein interaction network construction. Subsequently, a global triple network, including miRNAs, mRNAs, and transcription factors (TFs), was constructed. Furthermore, immune cell infiltration characteristics were analyzed to investigate the molecular immunology of lung transplant rejection. Finally, potential drug-target interactions were generated. In brief, 739 DEGs were found between rejection and stable LTx samples. PTPRC, IL-6, ITGAM, CD86, TLR8, TYROBP, CXCL10, ITGB2, and CCR5 were defined as hub genes. Eight TFs, including STAT1, SPIB, NFKB1, SPI1, STAT5A, RUNX1, VENTX, and BATF, and five miRNAs, including miR-335-5p, miR-26b-5p, miR-124-3p, miR-1-3p, and miR-155-5p, were involved in regulating hub genes. The immune cell infiltration analysis revealed higher proportions of activated memory CD4 T cells, follicular helper T cells, γδ T cells, monocytes, M1 and M2 macrophages, and eosinophils in rejection samples, besides lower proportions of resting memory CD4 T cells, regulatory T cells, activated NK cells, M0 macrophages, and resting mast cells. This study provided a comprehensive perspective of the molecular co-regulatory network underlying lung transplant rejection.