Blood mRNA and miRNA transcriptome to predict chronic lung allograft dysfunction

Chronic lung allograft dysfunction (CLAD) and its obstructive form, the obliterative bronchiolitis (OB), are the main long-term complications related to high mortality rate postlung transplantation. CLAD treatment lacks a significant success in survival. Here, we investigated a new strategy through inhibition of the proinflammatory mitogen- and stress-activated kinase 1 (MSK1) kinase. MSK1 expression was assessed in a mouse OB model after heterotopic tracheal allotransplantation. Pharmacological inhibition of MSK1 (H89, fasudil, PHA767491) was evaluated in the murine model and in a translational model using human lung primary fibroblasts in proinflammatory conditions. MSK1 expression was graded over time in biopsies from a cohort of CLAD patients. MSK1 mRNA progressively increased during OB (6.4-fold at D21 posttransplantation). Inhibition of MSK1 allowed to counteract the damage to the epithelium (56% restoration for H89), and abolished the recruitment of MHCII+ (94%) and T cells (100%) at the early inflammatory phase of OB. In addition, it markedly decreased the late fibroproliferative obstruction in allografts (48%). MSK1 inhibitors decreased production of IL-6 (whose transcription is under the control of MSK1) released from human lung fibroblasts (96%). Finally, we confirmed occurrence of a 2.9-fold increased MSK1 mRNA expression in lung biopsies in patients at 6 months before CLAD diagnosis as compared to recipients with stable lung function. These findings suggest the overall interest of the MSK1 kinase either as a marker or as a potential therapeutic target in lung dysfunction posttransplantation.

Cohort characteristics and chronic lung allograft dysfunction (CLAD) adjudication in a FP-7 funded project, systems prediction of CLAD (SysCLAD)

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.

Quantitative CT Imaging Analysis for Chronic Lung Allograft Dysfunction in Single Lung Transplant Recipients

Chronic lung allograft dysfunction (CLAD) limits long-term survival after lung transplantation. Of the two subtypes, restrictive allograft syndrome (RAS) is characterized by a larger lung volume decrease and worse prognosis than bronchiolitis obliterans syndrome (BOS). We used computed tomography (CT) volumetry to classify CLAD subtypes and determined their clinical impact. Adult primary lung transplants performed 2003-2015 (n=167) were retrospectively evaluated for CLAD and subclassified with CT volumetry. Lung volume decrease of<15% from baseline resulted in BOSCT-vol and ≥15% resulted in RASCT-vol diagnosis. Clinical impact of CLAD subtypes was defined, and the prognostic value of different lung function, radiological, and lung volume parameters present at the time of CLAD diagnosis were compared. CLAD affected 43% of patients and was classified with CT volumetry as BOSCT-vol in 89% and RASCT-vol in 11%. Median graft survival estimate in RASCT-vol was significantly decreased compared to BOSCT-vol (1.6vs. 9.7 years, P=.038). At CLAD onset, RASCT-vol diagnosis (P=.05), increased lung density (P=.007), and more severe FEV1 (P=.004) decline from baseline, increased graft loss risk in multivariate analysis. CT volumetry serves to identify lung transplant patients with a poor clinical outcome but should be validated in prospective trials.

Patients with Bronchiolitis Obliterans Syndrome (BOS) Have Later Onset of Acute Rejection Than BOS-Free Patients

Imaging Mass Cytometry for Detailed Cellular and Spatial Characterization of Chronic Lung Allograft Dysfunction (CLAD)

Differences in chronic lung allograft dysfunction between deceased-donor lung transplantation and living-donor lobar lung transplantation

Prediction of chronic lung allograft dysfunction: a systems medicine challenge

<b>Aims:</b> Long-term survival after lung transplantation (LT) is hampered by the occurrence of chronic lung allograft dysfunction (CLAD), manifesting as bronchiolitis obliterans syndrome (BOS) or restrictive allograft syndrome (RAS). CLAD is triggered by several factors, e.g. recurrent infections. As immunoglobulin (Ig) A is crucial to ensure mucosal immunity and limit airway microbial load, we explored whether IgA and its epithelial receptor, the polymeric Ig receptor (pIgR) are impaired in BOS. <b>Methods:</b> Bronchoalveolar lavages (BAL, n=120) from LT recipients included in the Cohort for Lung Transplantation were collected at pre-defined timepoints prior to the diagnosis of functional stability (BOS-free, n=30) or BOS (pre-BOS, n=30), and assessed for secretory (S)-IgA. Bronchiolar epithelium pIgR expression was quantified in transbronchial biopsies from BOS-free (n=20), pre-BOS (n=19) and BOS LT recipients (n=12), as well as in end-stage BOS explants (n=15). <b>Results:</b> S-IgA levels were reduced in BAL from pre-BOS LT recipients versus BOS-free (16.1 vs 33.4 µg/ml, p&lt;0.01). pIgR bronchiolar expression was reduced in transbronchial biopsies from BOS (p&lt;0.05 vs BOS-free and pre-BOS), with further decrease in end-stage BOS explants (p&lt;0.0001 vs BOS-free and pre-BOS). <b>Conclusions:</b> BAL S-IgA and pIgR decreased levels suggest that the pIgR/IgA system is impaired in BOS. This could play a pathogenic role by increasing susceptibility to local infections.

Background.Chronic rejection, defined as chronic lung allograft dysfunction (CLAD), is the major factor limiting long-term survival after lung transplantation (LTx). A specific subgroup of CLAD is restrictive allograft syndrome (RAS). CLAD’s pathogenesis is largely unknown, but previous findings suggest that it is associated with increased fibrosis in the transplanted lung. Cartilage oligomeric matrix protein (COMP) has been associated with multiple fibrotic conditions. The current study aimed to explore the relation between COMP serum levels and development of CLAD, and RAS in particular, in a retrospective cohort of LTx patients.Methods.This study included retrospective data from patients who underwent LTx during 2009–2011. Blood samples and spirometry data were obtained at follow-up visits 1, 3, 6, 9, and 12 mo after transplantation. Serum samples were analyzed for COMP. CLAD and RAS were defined according to the 2019 International Society for Heart and Lung Transplantation consensus document.Results.Data from 38 patients (19 men and women, respectively) were collected. Twenty-three patients (60.5%) developed CLAD, of whom 6 (26.1 %) fulfilled the criteria for RAS. Patients who developed RAS had higher mean COMP levels between 1 and 3 mo after LTx than those who did not develop RAS (10.9 [3.9-17.5] U/L vs 7.4 [3.9-10.8] U/L, P = 0.008). RAS was also associated with shorter survival. We found no association between COMP levels and CLAD of other types than RAS.Conclusions.Serum level of COMP early after LTx seems to be associated with RAS development and might serve as a biomarker suitable for clinical use in the LTx setting.

<b>Introduction:</b> For the diagnosis of Restrictive CLAD (rCLAD), a subtype of Chronic Lung Allograft Dysfunction (CLAD), a persistent decline in FEV1 with a concomitant decline in TLC &gt;10% or a decline in FVC&gt;20% is required. This study aims describe the changes in DLCo and propose a cutoff value for decline in DLCo. <b>Methods:</b> This is a retrospective 2 centre study comprising all double lung transplant recipients with onset of CLAD between 2010 and 2014 in Leuven and 2007-2014 in Copenhagen Including all pulmonary function variables <b>Results:</b> A total of 101 patients were included. 52 had BOS, 49 had rCLAD (based on either TLC and/or FVC decline). The change in DLCo from baseline to CLAd was different in the two groups with a median decline of -0.440±1.10 mmol/min/kPa in patients with BOS and a median of -1.280±1.01 mmol/min/kPa in all patients with rCLAD, p=0.006. ROC analysis demonstrated an area under the curve of 0.674 with an optimal threshold of 20% decline in DLCO. Survival after onset of CLAD stratified for DLCO decline ≥than 20% showed an impaired survival when DLCo has declined ≥20% at the onset of CLAD (p=0.012). <b>Conclusion:</b> This study demonstrates that recipients with rCLAD had a significantly larger decline in DLCo at the onset of CLAD compared to those with BOS. At a proposed cut-off value of 20% decline in DLCo there was an impaired survival after onset of CLAD, suggesting that the use of DLCo might be helpful diagnosing CLAD.

Small airway brush gene expression predicts chronic lung allograft dysfunction and mortality

Subclass specific antibody responses to HCMV in transplant recipients and their association with constant heavy IgG chain polymorphism and virus replication

Chronic lung allograft dysfunction (CLAD) is the major long-term cause of morbidity and mortality after lung transplantation. Both bronchiolitis obliterans syndrome and restrictive lung allograft syndrome, two main types of CLAD, lead to fibrosis in either the small airways or alveoli and pleura. Pathological pathways in CLAD and other types of fibrosis, for example idiopathic pulmonary fibrosis, are assumed to overlap and therefore fibrosis biomarkers could aid in the early detection of CLAD. These biomarkers could help to differentiate between different phenotypes of CLAD and could, in comparison to biomarkers of inflammation, possibly distinguish an infectious event from CLAD when a decline in lung function is present. This review gives an overview of known CLAD specific biomarkers, describes new promising fibrosis biomarkers currently investigated in other types of fibrosis, and discusses the possible use of these fibrosis biomarkers for CLAD.