Current views on chronic rejection after lung transplantation

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.

Anti-CD20 Antibody and Calcineurin Inhibitor Combination Therapy Effectively Suppresses Antibody-Mediated Rejection in Murine Orthotopic Lung Transplantation

Antibody-mediated rejection (AMR) is a risk factor for chronic lung allograft dysfunction, which impedes long-term survival after lung transplantation. There are no reports evaluating the efficacy of the single use of anti-CD20 antibodies (aCD20s) in addition to calcineurin inhibitors in preventing AMR. Thus, this study aimed to evaluate the efficacy of aCD20 treatment in a murine orthotopic lung transplantation model. Murine left lung transplantation was performed using a major alloantigen strain mismatch model (BALBc (H-2d) → C57BL/6 (BL/6) (H-2b)). There were four groups: isograft (BL/6→BL/6) (Iso control), no-medication (Allo control), cyclosporine A (CyA) treated, and CyA plus murine aCD20 (CyA+aCD20) treated groups. Severe neutrophil capillaritis, arteritis, and positive lung C4d staining were observed in the allograft model and CyA-only-treated groups. These findings were significantly improved in the CyA+aCD20 group compared with those in the Allo control and CyA groups. The B cell population in the spleen, lymph node, and graft lung as well as the levels of serum donor-specific IgM and interferon γ were significantly lower in the CyA+aCD20 group than in the CyA group. Calcineurin inhibitor-mediated immunosuppression combined with aCD20 therapy effectively suppressed AMR in lung transplantation by reducing donor-specific antibodies and complement activation.

Case Report: Non-negligible Epstein-Barr virus-associated posttransplant lymphoproliferative disorders in a lung transplant recipient

Background

Posttransplant lymphoproliferative disorders (PTLDs) are uncommon but serious complications in patients following solid organ transplantation. Primary Epstein-Barr virus (EBV) infection is a risk factor for the development of PTLD, especially early-onset PTLD, in EBV-negative recipients. To date, however, there are no specific guidelines on the threshold of EBV-DNA load for therapeutic intervention, the source for measurement (e.g., blood, bronchoalveolar fluid), or the use of antiviral agents as prophylaxis for early PTLD prevention in EBV-mismatched patients.

Methods

The present study describes a 56-year-old male lung transplant recipient diagnosed with EBV-associated PTLD.

Results

This patient had a history of invasive fungal disease and Mucor and Aspergillus fumigatus infections in the early post-transplant period, necessitating antifungal therapy throughout the course of the disease. The patient was EBV-positive 15 days after transplantation, with lung CT showing multiple bilateral nodules of varying sizes beginning 98 days after transplantation. A lung biopsy showed PTLD, and next-generation sequencing (NGS) revealed EBV. This patient, however, did not receive any antiviral therapy for early PTLD prevention or any PTLD-related treatment. He died 204 days after lung transplantation.

Conclusion

The present study describes a lung transplant recipient who developed EBV-associated PTLD, a non-negligible disease, after solid organ transplantation. Monitoring EBV-DNA load is important, as a sudden increase may be a sensitive indicator of PTLD. An earlier diagnosis may increase the likelihood of successful treatment.

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.

A prospective examination of swallow and cough dysfunction after lung transplantation

OBJECTIVES

Swallow and cough dysfunction are possible surgical complications of lung transplantation (LT). We examined voluntary cough strength, sensorimotor reflexive cough integrity, and swallow-related respiratory rate (RR) across swallowing safety and aspiration response groups in recovering LT recipients.

METHODS

Forty-five LT recipients underwent flexible endoscopic evaluation of swallowing indexed by the validated Penetration Aspiration Scale. RR before and after a 3-ounce water drinking task was measured. Voluntary and reflexive cough screening were performed to index motor and sensory outcomes. T-tests, one-way ANOVAs, and chi-square (odds ratios) were used.

RESULTS

60% of patients exhibited laryngeal penetration (n = 27) and 40% demonstrated tracheal aspiration (n = 18); 72% (n = 13) demonstrated silent aspiration. Baseline RR was higher in aspirators versus non-aspirators (26.5 vs. 22.6, p = 0.04) and in silent aspirators compared to non-silent aspirators (27.9 vs. 20.7, p = 0.01). RR change post-swallowing did not differ between aspiration response groups; however, it was significantly higher in aspirators compared to non-aspirators (3 vs. -2, p = 0.02). Compared to non-silent aspirators, silent aspirators demonstrated reduced voluntary cough peak expiratory flow (PEF; 166 vs. 324 L/min, p = 0.01). PEF, motor and urge to cough reflex cough ratings did not differ between aspirators and non-aspirators. Silent aspirators demonstrated a 7.5 times higher odds of failing reflex cough screening compared to non-silent aspirators (p = 0.07).

CONCLUSIONS

During the acute recovery period, all LT participants demonstrated some degree of unsafe swallowing and reduced voluntary cough strength. Silent aspirators exhibited elevated RR, reduced voluntary cough physiologic capacity to defend the airway, and a clinically distinguishable blunted motor response to reflex cough screening.

Diagnostic performance of electronic nose technology in chronic lung allograft dysfunction

BACKGROUND

There is a need for reliable biomarkers for the diagnosis of chronic lung allograft dysfunction (CLAD). In this light, we investigated the diagnostic value of exhaled breath analysis using an electronic nose (eNose) for CLAD, CLAD phenotype, and CLAD stage in lung transplant recipients (LTR).

METHODS

We performed eNose measurements in LTR with and without CLAD, visiting the outpatient clinic. Through supervised machine learning, the diagnostic value of eNose for CLAD was assessed in a random training and validation set. Next, we investigated the diagnostic value of the eNose measurements combined with known risk factors for CLAD. Model performance was evaluated using ROC-analysis.

RESULTS

We included 152 LTR (median age 60 years, 49% females), of whom 38 with CLAD. eNose-based classification of patients with and without CLAD provided an AUC of 0.86 in the training set, and 0.82 in the validation set. After adding established risk factors for CLAD (age, gender, type of transplantation, time after transplantation and prior occurrence of acute cellular rejection) to a model with the eNose data, the discriminative ability of the model improved to an AUC of 0.94 (p = 0.02) in the training set and 0.94 (p = 0.04) in the validation set. Discrimination between BOS and RAS was good (AUC 0.95). Discriminative ability for other phenotypes (AUCs ranging 0.50-0.92) or CLAD stages (AUC 0.56) was limited.

CONCLUSION

Exhaled breath analysis using eNose is a promising novel biomarker for enabling diagnosis and phenotyping CLAD. eNose technology could be a valuable addition to the diagnostic armamentarium for suspected graft failure in LTR.

Fifteen-Year Surveillance of LTR Receiving Pre-Emptive Therapy for CMV Infection: Prevention of CMV Disease and Incidence of CLAD

The efficacy of pre-emptive therapy in the prevention of cytomegalovirus (CMV) disease and the potential association of CMV infection with the occurrence of chronic lung allograft dysfunction (CLAD) was evaluated in 129 lung transplant recipients receiving pre-emptive therapy based on pp65-antigenemia or CMV-DNA in the blood and in the bronchoalveolar lavage. Seventy-one (55%) patients received pre-emptive ganciclovir/valganciclovir (GCV/VGCV) for CMV infection for a median of 28 (9-191) days. Possible CMV disease occurred in six (5%) patients and was healed after the GCV/VGCV therapy. The cumulative incidence of CLAD was 38% and 54% at 5 and 10 years. Acute rejection and CMV load in the blood (but not in the lung) were independent predictors of the occurrence of CLAD. Pre-emptive therapy is highly effective in preventing CMV disease in lung recipients and does not induce a superior incidence of CLAD compared to what reported for other cohorts of patients who received an extended antiviral prophylaxis.

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.

Ferret Lung Transplantation Models Differential Lymphoid Aggregate Morphology Between Restrictive and Obstructive Forms of Chronic Lung Allograft Dysfunction

BACKGROUND

Long-term survival after lung transplantation remains limited by chronic lung allograft dysfunction (CLAD). CLAD has 2 histologic phenotypes, namely obliterative bronchiolitis (OB) and restrictive alveolar fibroelastosis (AFE), which have distinct clinical presentations, pathologies, and outcomes. Understanding of OB versus AFE pathogenesis would improve with better animal models.

METHODS

We utilized a ferret orthotopic single-lung transplantation model to characterize allograft fibrosis as a histologic measure of CLAD. Native lobes and "No CLAD" allografts lacking aberrant histology were used as controls. We used morphometric analysis to evaluate the size and abundance of B-cell aggregates and tertiary lymphoid organs (TLOs) and their cell composition. Quantitative RNA expression of 47 target genes was performed simultaneously using a custom QuantiGene Plex Assay.

RESULTS

Ferret lung allografts develop the full spectrum of human CLAD histology including OB and AFE subtypes. While both OB and AFE allografts developed TLOs, TLO size and number were greater with AFE histology. More activated germinal center cells marked by B-cell lymphoma 6 Transcription Repressor, (B-cell lymphoma 6) expression and fewer cells expressing forkhead box P3 correlated with AFE, congruent with greater diffuse immunoglobulin, plasma cell abundance, and complement 4d staining. Furthermore, forkhead box P3 RNA induction was significant in OB allografts specifically. RNA expression changes were seen in native lobes of animals with AFE but not OB when compared with No CLAD native lobes.

CONCLUSIONS

The orthotopic ferret single-lung transplant model provides unique opportunities to better understand factors that dispose allografts to OB versus AFE. This will help develop potential immunomodulatory therapies and antifibrotic approaches for lung transplant patients.

Current trends in candidate selection, contraindications, and indications for lung transplantation

Lung transplantation is an established treatment option that can improve quality of life and prolong survival for select patients diagnosed with end-stage lung disease. Given the gaps in organ donation and failures to make effective use of available organs, careful selection of candidates for lung transplant remains one of the most important considerations of the transplant community. Toward this end, we briefly reviewed recent trends in pretransplant evaluation, candidate selection, organ allocation, and organ preservation techniques. Since the latest consensus statement regarding appropriate selection of lung transplant candidates, many advances in the science and practice of lung transplantation have emerged and influenced our perspective of ‘contraindications’ to transplant. These advances have made it increasingly possible to pursue lung transplant in patients with risk factors for decreased survival—namely, older recipient age, increased body mass index, previous chest surgery, poorer nutritional status, and presence of chronic infection, cardiovascular disease, or extrapulmonary comorbid conditions. Therefore, we reviewed the updated evidence demonstrating the prognostic impact of these risk factors in lung transplant recipients. Lastly, we reviewed the salient evidence for current trends in disease-specific indications for lung transplantation, such as chronic obstructive pulmonary disease, idiopathic pulmonary fibrosis, cystic fibrosis, emphysema due to alpha-1 antitrypsin deficiency, and pulmonary arterial hypertension, among other less common end-stage diseases. Overall, lung transplant remains an exciting field with considerable hope for patients as they experience remarkable improvements in quality of life and survival in the modern era.

Structured Reporting of Computed Tomography Examinations in Post-Lung Transplantation Patients

OBJECTIVE

The aim of this study was to evaluate the benefits and potential of structured reports (SR) for chest computed tomography after lung transplantation.

METHODS

Free-text reports (FTR) and SR were generated for 49 computed tomography scans. Clinical routine reports were used as FTR. Two pulmonologists rated formal aspects, completeness, clinical utility, and overall quality. Wilcoxon and McNemar tests were used for statistical analysis.

RESULTS

Structured reports received significantly higher ratings for all formals aspects (P < 0.001, respectively). Completeness was higher in SR with regard to evaluation of bronchiectases, bronchial anastomoses, bronchiolitic and fibrotic changes (P < 0.001, respectively), and air trapping (P = 0.012), but not signs of pneumonia (P = 0.5). Clinical utility and overall quality were rated significantly higher for SR than FTR (P < 0.001, respectively). However, report type did not influence initiation of further diagnostic or therapeutic measures (P = 0.307 and 1.0).

CONCLUSIONS

Structured reports are superior to FTR with regard to formal aspects, completeness, clinical utility, and overall satisfaction of referring pulmonologists.

Lung Transplantation: CT Assessment of Chronic Lung Allograft Dysfunction (CLAD)

Chronic lung allograft rejection remains one of the major causes of morbi-mortality after lung transplantation. The term Chronic Lung Allograft Dysfunction (CLAD) has been proposed to describe the different processes that lead to a significant and persistent deterioration in lung function without identifiable causes. The two main phenotypes of CLAD are Bronchiolitis Obliterans Syndrome (BOS) and Restrictive Allograft Syndrome (RAS), each of them characterized by particular functional and imaging features. These entities can be associated (mixed phenotype) or switched from one to the other. If CLAD remains a clinical diagnosis based on spirometry, computed tomography (CT) scan plays an important role in the diagnosis and follow-up of CLAD patients, to exclude identifiable causes of functional decline when CLAD is first suspected, to detect early abnormalities that can precede the diagnosis of CLAD (particularly RAS), to differentiate between the obstructive and restrictive phenotypes, and to detect exacerbations and evolution from one phenotype to the other. Recognition of early signs of rejection is crucial for better understanding of physiopathologic pathways and optimal management of patients.

Importance of the preoperative prognostic nutritional index score as a predictor of chronic lung allograft dysfunction after lung transplantation: a Japanese single-institution study

PURPOSES

Numerous indicators have been discussed as predictive markers for the incidence of chronic allograft dysfunction (CLAD) after lung transplantation (LTX). The aim of this study was to evaluate whether or not the preoperative prognostic nutrition index (PNI) correlated with the development of CLAD.

METHOD

This study is a single-center and retrospective cohort study. Forty-six patients underwent cadaveric lung transplantation between 2000 and 2016 at our institution. The primary endpoint of this study was the CLAD-free survival of the patients.

RESULT

CLAD was diagnosed in 11 patients (23%) during the follow-up period. Potential risk factors included recipient factors, donor factors, number of HLA mismatches, operation-related factors, and preoperative blood test results, including the preoperative PNI. The patients with a higher PNI showed a longer CLAD-free survival after LTX than those with lower values according to univariate and multivariate analyses (p = 0.01, 0.04, respectively). The 5-year CLAD-free survival rates in the higher-PNI patients and lower-PNI patients were 94% and 62%, respectively.

CONCLUSION

We found that a lower preoperative PNI of the recipient was significantly associated with a higher incidence rate of CLAD. The preoperative PNI may, therefore, be useful as a predictor of the development of CLAD.

Potential novel biomarkers for chronic lung allograft dysfunction and azithromycin responsive allograft dysfunction

Chronic Lung Allograft Dysfunction (CLAD), manifesting as Bronchiolitis Obliterans Syndrome (BOS) or Restrictive Allograft Syndrome (RAS), is the main reason for adverse long-term outcome after Lung Transplantation (LTX). Until now, no specific biomarkers exist to differentiate between CLAD phenotypes. Therefore, we sought to find suitable cytokines to distinguish between BOS, RAS and Azithromycin Responsive Allograft Dysfunction (ARAD); and reveal potential similarities or differences to end-stage fibrotic diseases. We observed significantly increased Lipocalin-2 serum concentrations in RAS compared to BOS patients. In addition, in RAS patients immunohistochemistry revealed Lipocalin-2 expression in bronchial epithelium and alveolar walls. Patients with ARAD showed significantly lower Activin-A serum concentrations compared to Stable-LTX and BOS patients. Further, increased serum concentrations of Lipocalin-2 and Activin-A were predictors of worse freedom-from-CLAD in Stable-LTX patients. These biomarkers serve as promising serum biomarkers for CLAD prediction and seem suitable for implementation in clinical practice.

Spectrum of findings on ventilation‒perfusion lung scintigraphy after lung transplantation and association with outcomes

BACKGROUND

Air trapping (AT) is one of the hallmarks of allograft dysfunction after lung transplantation (LT). Inert gas‒based ventilation‒perfusion (VQ) lung scintigraphy has excellent sensitivity in the detection of AT.

METHODS

We reviewed the charts of patients who underwent single or double LT between January 2012 and December 2014 (N = 193). Patients without a VQ scintigraphy at the first annual visit (n = 16) and those who did not survive till 1 year (n = 26) were excluded (final n = 151, mean age = 55.8 [SD =14] years, male = 85, female = 66). VQ scintigraphy was independently reviewed and reconciled for the presence and severity of AT by 2 investigators blinded to the clinical data (D.F.P. and D.M.). A 3-year post-transplant survival was the primary end-point.

RESULTS

AT was common (n = 73, 48.3%). Patients with obstructive lung diseases as the underlying diagnosis (adjusted odds ratio [OR], 4.36, 95% CI: 1.64‒11.6; p = 0.003) and those with lower body mass index (BMI) (BMI < 25 kg/m² and 25‒30 kg/m²; p < 0.001) had an increased risk of developing AT in the allograft. The presence of AT (adjusted OR, 2.33, 95% CI: 1.01‒5.36; p = 0.04) and peak forced expiratory volume in 1 sec (FEV₁) <60% predicted during the first year after LT were independently associated with 3-year mortality. The association of AT with post-transplant mortality was the strongest among patients with BMI <30 kg/m² and peak FEV₁ <60% predicted.

CONCLUSIONS

The finding of AT on VQ scintigraphy at the first annual visit after LT is independently associated with worse post-transplant mortality. The sub-group of patients who fail to achieve a peak FEV₁ of 60% predicted during the first year after LT appears to be the key driver of this association.

Chronic Lung Allograft Dysfunction: Review of CT and Pathologic Findings

Chronic lung allograft dysfunction (CLAD) is the most common cause of mortality in lung transplant recipients after the 1st year of transplantation. CLAD has traditionally been classified into two distinct obstructive and restrictive forms: bronchiolitis obliterans syndrome and restrictive allograft syndrome. However, CLAD may manifest with a spectrum of imaging and pathologic findings and a combination of obstructive and restrictive physiologic abnormalities. Although the initial CT manifestations of CLAD may be nonspecific, the progression of findings at follow-up should signal the possibility of CLAD and may be present on imaging studies prior to the development of functional abnormalities of the lung allograft. This review encompasses the evolution of CT findings in CLAD, with emphasis on the underlying pathogenesis and pathologic condition, to enhance understanding of imaging findings. The purpose of this article is to familiarize the radiologist with the initial and follow-up CT findings of the obstructive, restrictive, and mixed forms of CLAD, for which early diagnosis and treatment may result in improved survival. Supplemental material is available for this article. © RSNA, 2021.

[Fibrotic remodeling of the lung following lung and stem-cell transplantation]

Transplantation of solid organs and hematopoietic stem cells represents an important therapeutic option for a variety of end-stage pulmonary diseases, aggressive hematopoietic neoplasms, or severe immunodeficiencies. Although the overall survival following transplantation has generally improved over recent decades, long-time survival of lung and stem-cell transplant recipients is still alarmingly low with an average 5‑year survival rate of only 50-60%. Chronic allo-immunoreactions in general and pulmonary allo-immunoreactions with subsequent fibrosis in particular are major reasons for this poor outcome. Comparable patterns of fibrotic lung remodeling are observed following both lung and hematopoietic stem-cell transplantation. Besides the meanwhile well-established obliterative and functionally obstructive remodeling of the small airways - obliterative bronchiolitis - a specific restrictive subform of fibrosis, namely alveolar fibroelastosis, has been identified. Despite their crucial impact on patient outcome, both entities can be very challenging to detect by conventional histopathological analysis. Their underlying mechanisms are considered overreaching aberrant repair attempts to acute lung injuries with overactivation of (myo-) fibroblasts and excessive and irreversible deposition of extracellular matrix. Of note, the underlying molecular mechanisms are widely divergent between these two morphological entities and are independent of the underlying clinical setting.Further comprehensive investigations of these fibrotic alterations are key to the development of much-needed predictive diagnostics and curative concepts, considering the high mortality of pulmonary fibrosis following transplantation.

Evaluation of Quantiferon®-Monitor as a biomarker of immunosuppression and predictor of infection in lung transplant recipients

BACKGROUND

Optimizing immunosuppression in lung transplant recipients (LTR) is crucially important in minimizing the risk of infection and rejection. Quantiferon®-Monitor (QFM) is a candidate immune function biomarker which has not yet been rigorously evaluated in the lung transplant setting. The aim of this prospective cohort study was to explore relationships between QFM results, immunosuppression, and infection/rejection in LTR.

METHODS

QFM, which measures interferon-γ after stimulation with innate and adaptive immune antigens, was tested before and at 2, 6, 12, 24 and 52 weeks post-transplant. Immunosuppression relationships were assessed with linear mixed effects models. Clinical outcomes were analyzed based on the preceding QFM result.

RESULTS

Eighty LTR were included. Median pre-transplant QFM levels were 171 IU/mL (IQR 45-461), decreasing to 3 IU/mL (IQR 1-8) at 2 weeks post-transplant then progressively recovering toward baseline with time from transplant. Prednisolone was strongly inversely associated with QFM level (0.1 mg/kg dose increase correlating with 88 IU/mL QFM decrease, 95% CI 61-114, P < .001). Patients with QFM values <10 and <60 IU/mL were more likely to develop a serious opportunistic infection between 3 and 6 months (HR 6.38, 95% CI 1.37-29.66, P = .02) and 6-12 months (HR 3.25, 95% CI 1.11-9.49, P = .03) post-transplant, respectively.

CONCLUSIONS

QFM values declined significantly post-transplant, with patients recovering at different rates. Prednisolone dose significantly impacted QFM results. Low levels were associated with infection beyond 3 months post-transplant, suggesting that QFM may be able to identify overly immunosuppressed patients who could be targeted for dose reduction. Larger prospective studies are needed to further evaluate this promising assay.

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.

An update on current treatment strategies for managing bronchiolitis obliterans syndrome after lung transplantation

INTRODUCTION

Bronchiolitis obliterans syndrome (BOS), a subtype of chronic lung allograft dysfunction, is quite common, with up to half of all lung recipients developing BOS within 5 years of transplantation. Preventive efforts are aimed at alleviating known risk factors of BOS development, while the primary goal of treatment is to delay the irreversible, fibrotic airway changes, and progressive loss of lung function.

AREAS COVERED

This narrative review will briefly discuss the updated definition, clinical presentation, pathogenesis, risk factors, and survival after BOS while paying particular attention to the salient evidence for optimal preventive strategies and treatments based on investigations in the modern era.

EXPERT OPINION

Future translational research focused on further characterizing the complex interplay between immune and nonimmune mechanisms mediating chronic lung rejection is the first step toward mitigating risk of allograft injury, improving early disease detection with noninvasive biomarkers, and ultimately, developing an effective, targeted therapy that can extend the life of the lung allograft.

The autotaxin-lysophosphatidic acid pathway mediates mesenchymal cell recruitment and fibrotic contraction in lung transplant fibrosis

BACKGROUND

Chronic lung allograft dysfunction (CLAD) is the leading cause of mortality in lung transplant recipients. CLAD is characterized by respiratory failure owing to the accumulation of fibrotic cells in small airways and alveoli, inducing tissue contraction and architectural destruction. However, the source of the fibroblastic cells and the mechanism(s) underlying the accumulation and activation remain unexplained. Mesenchymal stromal cells (MSCs) are multipotent progenitors that are normally located in the lung tissue but can be isolated from the alveolar space in lung transplant recipients, where they have a profibrotic phenotype. Our objective was to identify the mediator(s) inducing migration and contractile differentiation of lung tissue MSCs.

METHODS

Bronchoalveolar lavage (BAL) (7 healthy controls and 21 lung transplant recipients), CCL2, HGF, TGFB, EGF, and PDGF-BB and autotaxin were measured by enzyme-linked immunosorbent assay. BAL (7 healthy controls and 31 lung transplant recipients) lysophosphatidic acid (LPA) (16:0, 18:0, 18:1, 22:4) was measured by liquid chromatography with tandem mass spectrometry. The effect of inhibition of candidate mediators on BAL-mediated chemoattraction of MSCs and contraction of MSC-spiked collagen gel assays was assessed. BAL cells from a lung transplant recipient with CLAD were analyzed by single-cell RNA sequencing.

RESULTS

We first demonstrate that BAL fluid from lung transplant recipients and particularly those with CLAD is potently chemoattractive to human lung tissue‒derived MSCs and induces a contractile phenotype. After excluding several candidate mediators, we show that LPA blockade completely abrogated transplant recipient BAL‒mediated chemoattraction of MSCs and contraction of MSC-spiked collagen gels. Furthermore, LPA levels were enriched in transplant recipient BAL, and LPA replicated the observed in vitro profibrotic effects of transplant recipient BAL. Finally, we identify BAL monocyte‒derived macrophages with autotaxin (ENPP2) and fibrotic transcriptional signature.

CONCLUSIONS

Autotaxin-expressing alveolar macrophages are present in CLAD BAL. These cells potentially provide a local source of autotaxin/LPA that drives MSC recruitment and tissue contraction in CLAD. These cells are analogous to an aberrant macrophage population recently identified in idiopathic pulmonary fibrosis, suggesting an overlap in pathogenesis between CLAD and other forms of lung fibrosis.

Usefulness of a preoperative inflammatory marker as a predictor of asymptomatic acute rejection after lung transplantation: a Japanese single-institution study

Background

Surveillance bronchoscopy (SB) is performed as routine follow-up after lung transplantation (LTx), primarily for the early detection of clinically asymptomatic acute rejection (AR). To identify appropriate candidates for SB over a long period, we explored risk factors of asymptomatic AR after LTx.

Method

This study is a single-center and retrospective cohort study. Forty-five patients underwent cadaveric LTx between 2000 and 2016 in our institution. All enrolled patients had at least three months of follow-up. SB is scheduled at 1, 2, 3, 6, and 12 months after LTx routinely and annually thereafter until 5 years after LTx. A histological assessment for AR was performed according to the International Society for Heart and Lung Transplantation (ISHLT) criteria. The analysis of potential risk factors for AR was performed using a chi-square test and logistic regression analysis.

Results

The median period of follow-up after LTx for the entire cohort was 64 months. Asymptomatic AR (grade A1-A3) was detected in 22 patients, 14 of whom showed severe AR (worse than grade A2). The percentage of patients with AR was 5–24% at each time point, and 15% of patients still showed severe AR (A2 and A3) at 24 months after LTx. Potential risk factors included recipient factors (diagnosis, age, gender, BMI), donor factors (age, gender, smoking history, cause of brain death), HLA mismatch, operation-related factors, neutrophil-to-leucocyte ratio (NLR), platelet-to-leucocyte ratio (PLR), and other scores. Patients with a higher NLR showed a higher incidence of AR after LTx than others during follow-up (P=0.01).

Conclusions

An increased perioperative NLR was significantly associated with a higher odds ratio of AR during follow-up. Patients with a high NLR seem to be good candidates for long-term SB.

Adherence is associated with a favorable outcome after lung transplantation

Non-adherence to therapy is associated with impaired outcome in solid organ allograft recipients. Outcome data are limited after lung transplantation. In a single-center cohort study, adherence was assessed in 427 patients undergoing lung transplantation from 2010 to 2013. Objective criteria of adherence were judged by health care workers on every visit on a five item Likert scale including trough level monitoring, home spirometry and contact with an overall rating of adherence between 0 and 100%. Cut-off values for good vs. suboptimal adherence were defined retrospectively. Primary outcome was allograft survival, secondary outcomes were patient survival, prevalence of chronic lung allograft dysfunction, hospitalizations, renal function and quality of life. Follow-up ended on 31st December 2018. Median adherence was 86% on 6,623 visits, this cut-off was used as a discriminator between good and suboptimal adherers. Patients with good adherence within the first three years showed better 5-year allograft (74% vs. 60%, p = 0.003) and patient survival (79% vs. 64%, p<0.001) and lower prevalence of chronic allograft dysfunction (33% vs. 45%, p = 0.011) after 5 years compared to patients with suboptimal adherence. A multidimensional adherence score proved to be a simple tool to assess adherence in clinical practice. Suboptimal adherence was associated with impaired outcome in lung transplant patients.

Pneumonia versus graft dysfunction as the cause of acute respiratory failure after lung transplant: a 4-year multicentre prospective study in 153 adults requiring intensive care admission

We aimed to assess the main causes of intensive care unit (ICU) readmissions in lung transplant adults and to identify independent predictors of ICU mortality (primary end-point).This Spanish five-centre prospective cohort study enrolled all lung transplant adults with ICU readmissions after post-transplant ICU discharge between 2012 and 2016. Patients were followed until hospital discharge or death.153 lung transplant recipients presented 174 ICU readmissions at a median (interquartile range) of 6 (2-25) months post-transplant. Chronic lung allograft dysfunction was reported in 39 (25.5%) recipients, 13 of whom (all exitus) had restrictive allograft syndrome (RAS). Acute respiratory failure (ARF) (110 (71.9%)) was the main condition requiring ICU readmission. Graft rejection (six (5.4%) acute) caused only 12 (10.8%) readmissions whereas pneumonia (56 (36.6%)) was the main cause (50 admitted for ARF and six for shock), with Pseudomonas aeruginosa (50% multidrug resistant) being the predominant pathogen. 55 (35.9%) and 69 (45.1%) recipients died in the ICU and the hospital, respectively. Bronchiolitis obliterans syndrome (BOS) stage 2 (adjusted OR (aOR) 7.2 (95% CI 1.0-65.7)), BOS stage 3 (aOR 13.7 (95% CI 2.5-95.3)), RAS (aOR >50) and pneumonia at ICU readmission (aOR 2.5 (95% CI 1.0-7.1)) were identified in multivariate analyses as independent predictors of ICU mortality. Only eight (5.2%) patients had positive donor-specific antibodies prior to ICU readmission and this variable did not affect the model.ARF was the main condition requiring ICU readmission in lung transplant recipients and was associated with high mortality. Pneumonia was the main cause of death and was also an independent predictor. RAS should receive palliative care rather than ICU admission.

Lung Transplantation and Precision Medicine

Lung transplantation is an accepted therapeutic option for end-stage lung diseases. Its history starts in the 1940s, initially hampered by early deaths due to perioperative problems and acute rejection. Improvement of surgical techniques and the introduction of immunosuppressive drugs resulted in longer survival. Chronic lung allograft dysfunction (CLAD), a new complication appeared and remains the most serious complication today. CLAD, the main reason why survival after lung transplantation is impaired compared to other solid-organ transplantations is characterized by a gradually increasing shortness of breath, reflected in a deterioration of pulmonary function status, respiratory insufficiency and possibly death.

FK506 combined with GM6001 prevents tracheal obliteration in a mouse model of heterotopic tracheal transplantation

BACKGROUND

Obliterative bronchiolitis (OB) is the major complication limiting the long-term survival of allografts after lung transplantation. In this study, we investigated the effect of tacrolimus (FK506) combined with GM6001，a matrix metalloproteinase (MMP) inhibitor， on the formation of OB using a mouse heterotopic tracheal transplantation model.

METHODS

Syngeneic tracheal grafts were transplanted heterotopically from BALB/c mice to BALB/c mice. Allografts from C57BL/6 mice were transplanted to BALB/c mice. Isograft group, allograft group, allograft+FK506 group, allograft +GM6001 group and allograft+FK506 + GM6001 group was given respectively intraperitoneal injection of saline, saline, FK506, GM6001 and FK506 + GM6001 once a day. At 28 day after transplantation, OB incidence was determined by hematoxylin-eosin staining and the expressions of MMPs and cytokines were assessed using enzyme linked immunosorbent assay, immunohistochemical assays and western blot assay.

RESULTS

The tracheal occlusion rates of isograft group, allograft group, allograft+FK506 group, allograft+GM6001 group and allograft+FK506 + GM6001 group were 0, 74.1 ± 9.79%, 34.4 ± 6.04%, 40.3 ± 8.77% and 26.5 ± 5.73% respectively. There were significant differences between the latter two groups (P < .001). The serum MMP-8 and MMP-9 levels of allograft group were significantly higher than those of isograft group (P < .05) and had no significant decrease when treated by FK506. The serum MMP-8 and MMP-9 levels of allograft+FK506 + GM6001 group were significantly lower than those of allograft+FK506 group (P < .05). MMP-8 and MMP-9 protein expression in the grafts of allograft+FK506 + GM6001 group were lower than those of allograft+FK506 group verified by immunohistochemical staining and western blotting.

CONCLUSION

FK506 combined with GM6001 could alleviate tracheal obliteration in mouse heterotopic tracheal transplantation model, due to its inhibitory effect on MMPs.

Survival Associated With Sirolimus Plus Tacrolimus Maintenance Without Induction Therapy Compared With Standard Immunosuppression After Lung Transplant

Importance

Median survival after lung transplant is less than 6 years. Standard maintenance therapy typically includes tacrolimus and an antimetabolite (mycophenolate mofetil or azathioprine). Replacing the antimetabolite with sirolimus after postoperative wound healing may improve long-term survival due to antifibrotic, antiproliferative, and antiaging effects of sirolimus.

Objectives

To compare survival between patients receiving sirolimus plus tacrolimus vs mycophenolate mofetil plus tacrolimus (the most common maintenance therapy) and to identify the combination of induction and maintenance therapy associated with the highest survival.

Design, Setting, and Participants

This cohort study of US recipients of lung transplants from January 1, 2003, through August 31, 2016, analyzed United Network for Organ Sharing (UNOS) data from January 1 through September 13, 2018. Because initiation of sirolimus therapy is usually delayed 3 to 12 months after lung transplant, primary analyses were based on patients alive and free of chronic rejection and malignant disease at 1 year in all groups, whereas sensitivity analyses used appropriate methods to include all patients from transplant time. Regression models adjusted for available potential confounders, including transplant center performance.

Exposures

Cell cycle inhibitor maintenance therapies, including sirolimus (n = 219), mycophenolate mofetil (n = 5782), mycophenolate sodium (n = 408), azathioprine (n = 2556), and concurrent sirolimus plus mycophenolate mofetil (n = 54), were compared within a tacrolimus-based regimen. Combinations of each induction (basiliximab, daclizumab, antithymocyte globulin, alemtuzumab, or none) and maintenance (tacrolimus plus sirolimus, mycophenolate mofetil, or azathioprine) therapy were also compared.

Main Outcomes and Measures

Survival was the primary outcome; chronic rejection incidence and subsequent mortality were secondary outcomes.

Results

Among this population of 9019 patients (median age, 57 years [interquartile range {IQR}, 46-63 years]; 5194 men [57.6%]), sirolimus plus tacrolimus was associated with better survival than mycophenolate mofetil plus tacrolimus (median, 8.9 years [IQR, 4.4-12.7 years] vs 7.1 years [IQR, 3.6-12.1 years]; adjusted hazard ratio [aHR], 0.71; 95% CI, 0.56-0.89; P = .003). Chronic rejection incidence (aHR, 0.75; 95% CI, 0.61-0.92) and mortality after chronic rejection (aHR, 0.52; 95% CI, 0.31-0.81) were lower with sirolimus plus tacrolimus. Compared with mycophenolate mofetil plus tacrolimus, survival differences for sirolimus plus mycophenolate mofetil plus tacrolimus (aHR, 1.14; 95% CI, 0.79-1.65), mycophenolate sodium plus tacrolimus (aHR, 0.95; 95% CI, 0.77-1.17), and azathioprine plus tacrolimus (aHR, 0.93; 95% CI, 0.84-1.02) were not significant. The induction-maintenance combination with the highest survival was sirolimus plus tacrolimus without induction therapy (median survival, 10.7 years [IQR, 7.3-12.7 years]; aHR, 0.48; 95% CI, 0.31-0.76; P = .002) compared with mycophenolate mofetil plus tacrolimus with induction therapy (median survival, 7.4 years [IQR, 3.9-12.6 years]).

Conclusions and Relevance

Sirolimus plus tacrolimus was associated with improved patient survival after lung transplant compared with mycophenolate mofetil plus tacrolimus; no antibody induction therapy with sirolimus plus tacrolimus was associated with maximal survival.

Impact of human leukocyte antigen mismatch on lung transplant outcome

OBJECTIVES

Human leucocyte antigen (HLA) mismatch between donor and recipient has a differential impact on the outcome after transplant (Tx) among transplantable solid organs. Although the lung is considered a highly antigenic organ, the impact of HLA matching between the donor and the recipient has been shown to be heterogeneous on lung Tx outcome. To provide further evidence that HLA matching should be considered in the decision process prior to lung Tx, we evaluated the impact of donor/recipient HLA mismatch on the outcome after lung Tx at our institution.

METHODS

All patients who underwent lung Tx were analysed in this retrospective single-cohort study between 1994 and 2013 for HLA (-A, -B or -DR) matching between the donor and the recipient and their association with overall survival, the incidence of acute cellular rejection (ACR) and the development of chronic lung allograft dysfunction (CLAD).

RESULTS

In total, 371 (197 men) patients were included. Of these, 117 patients had no HLA match (0/6), 143 had a 1/6 match, 77 had 2/6 matches, 28 had 3/6 matches and 6 had 4/6 matches. One hundred and twenty-two (33%) patients experienced at least 1 episode of ACR and 172 (46%) patients developed CLAD. Univariate analysis showed a significant correlation between HLA mismatch and the development of CLAD, whereas multivariate analysis revealed that the number of HLA matches (hazard ratio 0.76; P = 0.002), antibodies to cytomegalovirus in either donors or recipients (hazard ratio 1.52; P = 0.036) and donor age (hazard ratio 1.03; P < 0.001) were independent risk factors for the development of CLAD. On the other hand, HLA matches did not correlate with the incidence of ACR and with the overall survival rate.

CONCLUSIONS

The number of HLA mismatches between donors and recipients after lung Tx did not correlate with ACR or with the overall survival. In contrast, HLA mismatch correlated with the development of CLAD and should therefore be considered a risk factor.

A Pilot Study to Investigate the Balance between Proteases and α1-Antitrypsin in Bronchoalveolar Lavage Fluid of Lung Transplant Recipients

The neutrophilic component in bronchiolitis obliterans syndrome (BOS, the main form of chronic lung rejection), plays a crucial role in the pathogenesis and maintenance of the disorder. Human Neutrophil Elastase (HNE), a serine protease responsible of elastin degradation whose action is counteracted by α1-antitrypsin (AAT), a serum inhibitor specific for this protease. This work aimed to investigate the relationship between HNE and AAT in bronchoalveolar lavage fluid (BALf) from stable lung transplant recipients and BOS patients to understand whether the imbalance between proteases and inhibitors is relevant to the development of BOS. To reach this goal a multidisciplinary procedure was applied which included: (i) the use of electrophoresis/western blotting coupled with liquid chromatography-mass spectrometric analysis; (ii) the functional evaluation of the residual antiprotease activity, and (iii) a neutrophil count. The results of these experiments demonstrated, for the first time, the presence of the complex between HNE and AAT in a number of BALf samples. The lack of this complex in a few specimens analyzed was investigated in relation to a patient’s lung inflammation. The neutrophil count and the determination of HNE and AAT activities allowed us to speculate that the presence of the complex correlated with the level of lung inflammation.

Inhibition of B cell-dependent lymphoid follicle formation prevents lymphocytic bronchiolitis after lung transplantation

Lung transplantation (LTx) is the only therapeutic option for many patients with chronic lung disease. However, long-term survival after LTx is severely compromised by chronic rejection (chronic lung allograft dysfunction [CLAD]), which affects 50% of recipients after 5 years. The underlying mechanisms for CLAD are poorly understood, largely due to a lack of clinically relevant animal models, but lymphocytic bronchiolitis is an early sign of CLAD. Here, we report that lymphocytic bronchiolitis occurs early in a long-term murine orthotopic LTx model, based on a single mismatch (grafts from HLA-A2:B6-knockin donors transplanted into B6 recipients). Lymphocytic bronchiolitis is followed by formation of B cell-dependent lymphoid follicles that induce adjacent bronchial epithelial cell dysfunction in a spatiotemporal fashion. B cell deficiency using recipient μMT-/- mice prevented intrapulmonary lymphoid follicle formation and lymphocytic bronchiolitis. Importantly, selective inhibition of the follicle-organizing receptor EBI2, using genetic deletion or pharmacologic inhibition, prevented functional and histological deterioration of mismatched lung grafts. In sum, we provided what we believe to be a mouse model of chronic rejection and lymphocytic bronchiolitis after LTx and identified intrapulmonary lymphoid follicle formation as a target for pharmacological intervention of long-term allograft dysfunction after LTx.

Banff Lung Report: Current knowledge and future research perspectives for diagnosis and treatment of pulmonary antibody-mediated rejection (AMR)

The Lung session of the 2017 14th Banff Foundation for Allograft Pathology Conference, Barcelona focused on the multiple aspects of antibody-mediated rejection (AMR) in lung transplantation. Multidimensional approaches for AMR diagnosis, including classification, histological and immunohistochemical analysis, and donor- specific antibody (DSA) characterization with their current strengths and limitations were reviewed in view of recent research. The group also discussed the role of tissue gene expression analysis in the context of unmet needs in lung transplantation. The current best practice for monitoring of AMR and the therapeutic approach are summarized and highlighted in this report. The working group reached consensus of the major gaps in current knowledge and focused on the unanswered questions regarding pulmonary AMR. An important outcome of the meeting was agreement on the need for future collaborative research projects to address these gaps in the field of lung transplantation.

Long-Term Outcomes of Adult Lung Transplantation Recipients: A Single-Center Experience in South Korea

Background

Recently, the number of lung transplants in South Korea has increased. However, the long-term outcome data is limited. In this study, we aimed to investigate the long-term outcomes of adult lung transplantation recipients.

Methods

Among the patients that underwent lung transplantation at a tertiary referral center in South Korea between 2008 and 2017, adults patient who underwent deceased-donor lung transplantation with available follow-up data were enrolled. Their medical records were retrospectively reviewed.

Results

Through eligibility screening, we identified 60 adult patients that underwent lung (n=51) or heart-lung transplantation (n=9) during the observation period. Idiopathic pulmonary fibrosis (46.7%, 28/60) was the most frequent cause of lung transplantation. For all the 60 patients, the median follow-up duration for post-transplantation was 2.6 years (range, 0.01–7.6). During the post-transplantation follow-up period, 19 patients (31.7%) died at a median duration of 194 days. The survival rates were 75.5%, 67.6%, and 61.8% at 1 year, 3 years, and 5 years, respectively. Out of the 60 patients, 8 (13.3%) were diagnosed with chronic lung allograft dysfunction (CLAD), after a mean duration of 3.3±2.8 years post-transplantation. The CLAD development rate was 0%, 17.7%, and 25.8% at 1 year, 3 years, and 5 years, respectively. The most common newly developed post-transplantation comorbidity was the chronic kidney disease (CKD; 54.0%), followed by diabetes mellitus (25.9%).

Conclusion

Among the adult lung transplantation recipients at a South Korea tertiary referral center, the long-term survival rates were favorable. The proportion of patients who developed CLAD was not substantial. CKD was the most common post-transplantation comorbidity.

miR-199b-5p Regulates Immune-Mediated Allograft Rejection after Lung Transplantation Through the GSK3β and NF-κB Pathways

Emerging evidence indicates that acute rejection mainly associated with the inflammatory response is an independent risk factor for chronic rejection after lung transplantation. Monocytes are the main pro-inflammatory leukocytes infiltrating around the lesions and play vital roles in triggering the acute rejection. In the rat lung transplantation model, lipopolysaccharide (LPS)-induced severe acute rejection was strongly associated with advanced chronic rejection. The exact regulatory mechanism of pro-inflammation in monocytes is not yet clear. In this study, we identified a novel anti-inflammatory effect of miR-199b-5p (miR-199b) through the GSK3β and NF-κB pathways. THP-1 monocytes treated with LPS showed a significant decrease in miR-199b that is inversely correlated to GSK3β expression and NF-κB activation. Furthermore, the NF-κB-associated inflammatory response was reduced due to the overexpression of miR-199b targeting GSK3β, which was rescued by the inhibition of miR-199b. These results indicated that miR-199b attenuated the inflammatory response at least partly through the GSK3β/NF-κB signaling pathways in monocytes. Our data point toward a potentially important role for miR-199b in the inhibition of rejection after lung transplantation.

Unilateral Chronic Lung Allograft Dysfunction Assessed by Biphasic Computed Tomographic Volumetry in Bilateral Living-donor Lobar Lung Transplantation

Background

Early diagnosis of unilateral chronic lung allograft dysfunction (CLAD) is difficult because the unaffected contralateral lung functions as a reservoir in bilateral living-donor lobar lung transplantation (LDLLT). We previously reported the usefulness of ¹³³Xe ventilation scintigraphy for detection of unilateral change, but the supply of ¹³³Xe has been stopped globally. The present study aimed to examine the usefulness of inspiratory and expiratory computed tomography (I/E CT) volumetry for detection of unilateral change in CLAD patients.

Methods

This was a retrospective single-center, observational study using prospectively collected data. A total of 58 patients who underwent bilateral LDLLT from August 2008 to February 2017 were analyzed. Respiratory function tests, I/E CT were prospectively conducted. ΔLung volume was defined as the value obtained by subtracting expiratory lung volume from inspiratory lung volume.

Results

Fourteen (24%) cases were clinically diagnosed with CLAD, of which 10 (71%) were diagnosed as unilateral CLAD. ΔLung volume of bilateral lungs strongly correlated with forced vital capacity (r = 0.92, P < 0.01) and forced expiratory volume in 1 second (r = 0.80, P < 0.01). Regardless the phenotypes (bronchiolitis obliterans syndrome or restrictive allograft syndrome) of CLAD, Δlung volume onset/baseline significantly decreased compared with that in the non-CLAD group. Among the 10 unilateral CLAD patients, 3 with clinically suspected unilateral rejection yet did not show a 20% decline in forced expiratory volume in 1 second. In 2 of these, Δlung volume of unilateral lungs on the rejection side decreased by 20% or more.

Conclusions

Our findings suggest that I/E CT volumetry may be useful for assessment and early diagnosis of unilateral CLAD after bilateral LDLLT.

The Future of Lung Transplantation

The field of lung transplant has made significant advances over the last several decades. Despite these advances, morbidity and mortality remain high when compared with other solid organ transplants. As the field moves forward, the speed by which progress can be made will in part be determined by our ability to overcome several stumbling blocks, including donor shortage, proper selection of candidates, primary graft dysfunction, and chronic lung allograft dysfunction. The advances and developments surrounding these factors will have a significant impact on shaping the field within the coming years. In this review, we look at the current climate (ripe for expanding the donor pool), new technology (ex vivo lung perfusion and bioengineered lungs), cutting-edge innovation (novel biomarkers and new ways to treat infected donors), and evidence-based medicine to discuss current trends and predict future developments for what we hope is a bright future for the field of lung transplantation.

Lobe-wise assessment of lung volume and density distribution in lung transplant patients and value for early detection of bronchiolitis obliterans syndrome

PURPOSE

To evaluate quantitative computed tomography (CT) measurements of the lung parenchyma in lung transplant (LTx) patients for early detection of the bronchiolitis obliterans syndrome (BOS).

MATERIALS AND METHODS

359 CT scans of 122 lung transplant patients were evaluated. Measurements of lung volume and density were performed for the whole lung and separately for each lobe. For longitudinal analysis the difference between the baseline at 6 months after LTx and follow-up examinations was calculated. Patients with and without BOS (matched 1:2) were compared at two different time points, the last examination before the BOS onset and the first examination within one year after BOS onset.

RESULTS

30 patients developed BOS during the follow-up period. Longitudinal changes in the lung volume and lung density measured on CT differed significantly between those patients with and without early BOS, in particular the difference of the inspiratory and expiratory lung volume (p < 0.001), the ratio of the expiratory and inspiratory lung volume (p < 0.001-p = 0.001) and MLD (p < 0.001-p = 0.001), the volume on expiration (p < 0.001-p = 0.007), the MLD on expiration (p < 0.001-p = 0.007), and the percentiles on expiration (p < 0.001-p = 0.002) with an increase of lung volume and a decrease of lung density. Changes were pronounced in the lower lobes. Before BOS onset, patients with and without future development of BOS showed no significant differences.

CONCLUSION

Longitudinal changes of lung volume and lung density measured on CT start markedly at BOS onset with increased lung volume and decreased lung density indicating increased inflation levels. Even though this method may help to diagnose BOS at onset it is not useful as a predictor for BOS before disease onset.

Viral Respiratory Tract Infection During the First Postoperative Year Is a Risk Factor for Chronic Rejection After Lung Transplantation

Supplemental digital content is available in the text.

Background

Chronic lung allograft dysfunction (CLAD) is the major limiting factor for long-term survival in lung transplant recipients. Viral respiratory tract infection (VRTI) has been previously associated with CLAD development. The main purpose of this study was to evaluate the long-term effects of VRTI during the first year after lung transplantation in relation to CLAD development.

Method

Ninety-eight patients undergoing lung transplantation were prospectively enrolled between 2009 and 2012. They were monitored for infections with predefined intervals and on extra visits during the first year, the total follow-up period ranged between 5 and 8 years. Nasopharyngeal swab and bronchoalveolar lavage samples were analyzed using a multiplex polymerase chain reaction panel for respiratory pathogens. Data regarding clinical characteristics and infectious events were recorded.

Results

Viral respiratory tract infection during the first year was identified as a risk factor for long-term CLAD development (P = 0.041, hazard ratio 1.94 [1.03-3.66]) in a time-dependent multivariate Cox regression analysis. We also found that coronavirus in particular was associated with increased risk for CLAD development. Other identified risk factors were acute rejection and cyclosporine treatment.

Conclusions

This study suggests that VRTI during the first year after lung transplantation is associated with long-term CLAD development and that coronavirus infections in particular might be a risk factor.

High-Resolution CT Findings of Obstructive and Restrictive Phenotypes of Chronic Lung Allograft Dysfunction: More Than Just Bronchiolitis Obliterans Syndrome

OBJECTIVE

The purpose of this article is to review the high-resolution CT characteristics of individual obstructive and restrictive chronic lung allograft dysfunction (CLAD) phenotypes to aid in making accurate diagnoses and guiding treatment.

CONCLUSION

Long-term survival and function after lung transplant are considerably worse compared with after other organ transplants. CLAD is implicated as a major limiting factor for long-term graft viability. Historically thought to be a single entity, bronchiolitis obliterans syndrome, CLAD is actually a heterogeneous group of disorders with distinct subtypes.

Prevention of chronic rejection after lung transplantation

Long-term survival after lung transplantation (LTx) is limited by chronic rejection (CR). Therapeutic strategies for CR have been largely unsuccessful, making prevention of CR an important and challenging therapeutic approach. In the current review, we will discuss current clinical evidence regarding prevention of CR after LTx.