Background: There are limited data on optimal management of chronic lung allograft dysfunction (CLAD). We aimed to describe the variability of diagnostic and therapeutic practices in Europe.Methods: A structured questionnaire was sent to 71 centres in 24 countries. Questions were related to contemporary clinical practices for workup, monitoring and treatment of CLAD. The number of lung transplant procedures and patients in follow-up were collected.Results: 44 centres (62%) responded from 20 countries, representing 74% of European activity. The prevalence of CLAD was estimated at 9.1 cases per million population (25th and 75th percentiles of 4.4, 15.7). Preferred initial workup for probable CLAD consisted of chest computed tomography (CT) (inspiratory 91% and expiratory 74%), donor-specific antibody (DSA) measurement (86%), bronchoalveolar lavage (BAL) (85%) and transbronchial biopsy (81%). For monitoring of definite CLAD, inspiratory CT (67%), DSA (61%) and BAL (43%) were preferred. Body plethysmography was unavailable for 16% of cases. Prophylaxis was based on preventing infections (cytomegalovirus 99%, inhaled antibiotics 70% and antifungals 65%), tacrolimus-based immunosuppression (96%), azithromycin (72%) and universal proton pump inhibitor treatment (84%). First-line treatment of CLAD was based on azithromycin (82%) and steroid augmentation (74%). Photopheresis was used in 26% of cases.Conclusion: Current European practice CLAD detection is based on spirometry, inspiratory CT and DSA, with limited access to plethysmography and expiratory CT. Prophylactic treatment is based on azithromycin, tacrolimus-based immunosuppression and treatment of risk factors. No single treatment strategy is universally used, highlighting the need for an effective treatment of CLAD. The preferred first-line strategy is azithromycin and steroid augmentation.

While cytomegalovirus (CMV) viremia/DNAemia has been associated with reduced survival after lung transplantation, its association with chronic lung allograft dysfunction (CLAD) and its phenotypes is unclear. We hypothesized that, in a modern era of CMV prophylaxis, CMV DNAemia would still remain associated with death, but also represent a risk factor for CLAD and specifically restrictive allograft syndrome (RAS)/mixed phenotype. This was a single-center retrospective cohort study of all consecutive adult, first, bilateral-/single-lung transplants done 2010-2016, consisting of 668 patients. Risks for death/re-transplantation, CLAD, or RAS/mixed, were assessed by adjusted cause-specific Cox proportional-hazards models. CMV viral load (VL) was primarily modeled as a categorical variable: undetectable, detectable-999, 1000-9999, and ≧10000 IU/mL. In multivariable models, CMV VL was significantly associated with death/re-transplantation (≧10000 IU/mL: HR=2.65 (1.78-3.94), p<0.01), but was not associated with CLAD, whereas CMV serostatus mismatch was (D+R-: HR=2.04 (1.30-3.21), p<0.01). CMV VL was not associated with RAS/mixed in univariable analysis. Secondary analyses with a 7-level categorical or 4-level ordinal CMV VL confirmed similar results. In conclusion, CMV DNAemia is a significant risk factor for death/re-transplantation, but not for CLAD or RAS/mixed. CMV serostatus mismatch may have an impact on CLAD through a pathway independent of DNAemia.

Chronic lung allograft dysfunction (CLAD) is the major cause of death after lung transplantation. Angiotensin II (AngII), the main effector of the renin–angiotensin system, elicits fibrosis in both kidney and lung. We identified six AngII-regulated proteins (Ras homolog family member B (RHOB), bone marrow stromal cell antigen 1 (BST1), lysophospholipase 1 (LYPA1), glutamine synthetase (GLNA), thrombospondin 1 (TSP1) and laminin subunit β2 (LAMB2)) that were increased in urine of patients with kidney allograft fibrosis. We hypothesised that the renin–angiotensin system is active in CLAD and that AngII-regulated proteins are increased in bronchoalveolar lavage fluid (BAL) of CLAD patients.We performed immunostaining of AngII receptors (AGTR1 and AGTR2), TSP1 and GLNA in 10 CLAD lungs and five controls. Using mass spectrometry, we quantified peptides corresponding to AngII-regulated proteins in BAL of 40 lung transplant recipients (stable, acute lung allograft dysfunction (ALAD) and CLAD). Machine learning algorithms were developed to predict CLAD based on BAL peptide concentrations.Immunostaining demonstrated significantly more AGTR1⁺cells in CLADversuscontrol lungs (p=0.02). TSP1 and GLNA immunostaining positively correlated with the degree of lung fibrosis (R²=0.42 and 0.57, respectively). In BAL, we noted a trend towards higher concentrations of AngII-regulated peptides in patients with CLAD at the time of bronchoscopy, and significantly higher concentrations of BST1, GLNA and RHOB peptides in patients that developed CLAD at follow-up (p<0.05). The support vector machine classifier discriminated CLAD from stable and ALAD patients at the time of bronchoscopy (area under the curve (AUC) 0.86) and accurately predicted subsequent CLAD development (AUC 0.97).Proteins involved in the renin–angiotensin system are increased in CLAD lungs and BAL. AngII-regulated peptides measured in BAL may accurately identify patients with CLAD and predict subsequent CLAD development.

Question addressed by the study: Do three coronavirus disease 2019 (COVID-19) vaccine doses induce a serological response in lung transplant recipients?Methods: We retrospectively included 1071 adults (551 (52%) males) at nine transplant centres in France. Each had received three COVID-19 vaccine doses in 2021, after lung transplantation. An anti-spike protein IgG response, defined as a titre >264 BAU·mL⁻¹after the third dose (median (interquartile range (IQR)) 3.0 (1.7–4.1) months), was the primary outcome and adverse events were the secondary outcomes. Median (IQR) age at the first vaccine dose was 54 (40–63) years and median (IQR) time from transplantation to the first dose was 64 (30–110) months.Results: Median (IQR) follow-up after the first dose was 8.3 (6.7–9.3) months. A vaccine response developed in 173 (16%) patients. Factors independently associated with a response were younger age at vaccination, longer time from transplantation to vaccination and absence of corticosteroid or mycophenolate therapy. After vaccination, 51 (5%) patients (47 non-responders (47/898 (5%)) and four (4/173 (2%)) responders) experienced COVID-19, at a median (IQR) of 6.6 (5.1–7.3) months after the third dose. No responders had severe COVID-19 compared with 15 non-responders, including six who died of the disease.Conclusions: Few lung transplant recipients achieved a serological response to three COVID-19 vaccine doses, indicating a need for other protective measures. Older age and use of mycophenolate or corticosteroids were associated with absence of a response. The low incidence of COVID-19 might reflect vaccine protectionviacellular immunity and/or good adherence to shielding measures.