The nature of chronic rejection after lung transplantation: a murine orthotopic lung transplant study.

Introduction: Chronic rejection is a major complication post-transplantation. Within lung transplantation, chronic rejection was considered as airway centred. Chronic Lung Allograft Dysfunction (CLAD), defined to cover all late chronic complications, makes it more difficult to understand chronic rejection from an immunological perspective. This study investigated the true nature, timing and location of chronic rejection as a whole, within mouse lung transplantation. Methods: 40 mice underwent an orthotopic left lung transplantation, were sacrificed at day 70 and evaluated by histology and in vivo µCT. For timing and location of rejection, extra grafts were sacrificed at day 7, 35, 56 and investigated by ex vivo µCT or single cell RNA (scRNA) profiling. Results: Chronic rejection originated as innate inflammation around small arteries evolving toward adaptive organization with subsequent end-arterial fibrosis and obliterans. Subsequently, venous and pleural infiltration appeared, followed by airway related bronchiolar folding and rarely bronchiolitis obliterans was observed. Ex vivo µCT and scRNA profiling validated the time, location and sequence of events with endothelial destruction and activation as primary onset. Conclusion: Against the current belief, chronic rejection in lung transplantation may start as an arterial response, followed by responses in venules, pleura, and, only in the late stage, bronchioles, as may be seen in some but not all patients with CLAD.

Association Between FEV1 Decline Rate and Mortality in Long-Term Follow-Up of a 21-Patient Pilot Clinical Trial of Inhaled Liposomal Cyclosporine Plus Standard-of-Care Versus Standard-of-Care Alone for Bronchiolitis Obliterans Syndrome After Lung Transplantation.

BACKGROUND The association between forced expiratory volume in 1 second (FEV1) trajectory and mortality in bronchiolitis obliterans syndrome (BOS) is not well defined. Using long-term data from a prior clinical trial of inhaled liposomal cyclosporine A (L-CsA-I) for lung transplant patients with BOS, this study examined the association between longitudinal FEV1 change and mortality. MATERIAL AND METHODS We analyzed long-term data from a clinical trial which randomized 21 patients with BOS (³20% decrease in FEV1 from personal maximum) to receive L-CsA-I plus standard-of-care (n=11) or standard-of-care (SOC) alone (n=10) for 24 weeks. A joint statistical model, combining a linear mixed model for FEV1 change and Cox regression for mortality, was utilized to examine the overall association between FEV1 trajectory and mortality during follow-up. RESULTS The 21 trial participants (10 single, 11 double lung recipients) had a mean FEV1 of 1.7±0.6 Liters at randomization. Median follow-up post-randomization was 35 months. In joint model analysis, 1 percent FEV1 decline predicted 1.076-fold increased mortality risk (95% confidence interval: -0.998 to 1.160, p=0.058). FEV1 decline was reduced by 2.6% per year in L-CsA-I patients compared to SOC (p=0.210), and overall survival at 1/3/5 years was 91%/64%/27% vs 90%/20%/0% for L-CsA-I versus SOC, respectively (p=0.164). CONCLUSIONS In BOS patients, greater longitudinal FEV1 decline predicts increased mortality. Trends towards prolonged stabilization of FEV1 and improved survival were observed with L-CsA-I receipt. Further analyses will aid in evaluating the utility of FEV1 change as a survival predictor, having implications in BOS management and future trial design.

A review of the therapeutic potential of the cysteinyl leukotriene antagonist Montelukast in the treatment of bronchiolitis obliterans syndrome following lung and hematopoietic-stem cell transplantation and its possible mechanisms.

Lung and hematopoietic stem cell transplantation are therapeutic modalities in chronic pulmonary and hematological diseases, respectively. One of the complications in these patients is the development of bronchiolitis obliterans syndrome (BOS). The efficacy and safety of available treatment strategies in BOS remain a challenge. A few mechanisms have been recognized for BOS in lung transplant and graft-versus-host disease (GVHD) patients involving the TH-1 and TH-2 cells, NF-kappa B, TGF-b, several cytokines and chemokines, and cysteinyl leukotrienes (CysLT). Montelukast is a highly selective CysLT receptor antagonist that has been demonstrated to exert anti-inflammatory and anti-fibrotic effects in abundant experiments. One area of interest for the use of montelukast is lung transplants or GVHD-associated BOS. Herein, we briefly review data regarding the mechanisms involved in BOS development and montelukast administration as a treatment modality for BOS, and finally, the possible relationship between CysLTs antagonism and BOS improvement will be discussed.

A review of the therapeutic potential and possible mechanism of Montelukast in the treatment of bronchiolitis obliterans syndrome following lung and hematopoietic stem cell transplantationLung and bone marrow transplantation are therapeutic modalities in chronic diseases of the lungs and the blood, respectively. One of the complications in these patients is the development of Bronchiolitis obliterans syndrome (BOS). The efficacy and safety of available treatment strategies in BOS remain a challenge. A few mechanisms for BOS in lung transplant and graft-versus-host disease (GVHD) patients involving many immune components have been recognized. Cysteinyl leukotrienes are products of plasma membrane phospholipids that increase smooth muscle contraction, microvascular permeability, and airway mucus secretion. Montelukast is a highly selective cysteinyl leukotriene receptor blocker demonstrated to exert anti-inflammatory and anti-fibrotic effects. One area of interest for the use of montelukast is in lung transplant- or GVHD-associated BOS. In this article, we briefly review data regarding the mechanisms involved in BOS development and montelukast administration as a treatment modality for BOS. Finally, the possible relationship between cysteinyl leukotriene inhibition and BOS improvement will be discussed.

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.

IL-27 Levels in Bronchoalveolar Lavage Fluid in Children with Post-infectious Bronchiolitis Obliterans.

Background: Pulmonary neutrophils may play a crucial role in the development of bronchiolitis obliterans (BO) following measles virus infection. IL-27 could potentially have a negative regulatory effect on the release of reactive oxygen species and cytotoxic granules in neutrophils. Objective: To investigate the levels of IL-27 in the bronchoalveolar lavage fluid (BALF) of children with post-infectious bronchiolitis obliterans (PIBO) and analyze the relationship between IL-27 levels and neutrophil proportions. Methods: A total of 24 children with PIBO were recruited for the experimental group, while 23 children with bronchial foreign bodies were included in the control group. Bronchoscopic alveolar lavage was performed in both groups. The levels of IL-27 in BALF were measured using enzyme-linked immunosorbent assay (ELISA). The proportions of neutrophils in BALF were determined by smear staining. The relationship between the levels of IL-27 in BALF and the neutrophil proportions was analyzed by the Pearson test. Results: The levels of IL-27 in BALF were significantly lower in children with PIBO compared to children with bronchial foreign bodies (p<0.05). Additionally, the proportions of neutrophils in BALF were significantly higher in children with PIBO compared to children with bronchial foreign bodies (p<0.05). The levels of IL-27 were negatively correlated with the neutrophil proportions in BALF in children with PIBO (p<0.05), but not in children with bronchial foreign bodies (p>0.05). Conclusion: The present study suggests that a decrease in IL-27 may be associated with an increase in neutrophils in BALF and may contribute to the pathogenesis of PIBO.

Detection of Bronchiolitis Obliterans Syndrome Using Nitrogen Multiple Breath Washout in Children Posthemopoietic Stem Cell Transplant.

Bronchiolitis obliterans syndrome (BOS) is a severe complication following hemopoietic stem cell transplantation (HSCT) and is often undetected until there is significant deterioration in pulmonary function. Lung clearance index (LCI2.5) derived from the nitrogen multiple breath washout (N2MBW) test may be more feasible and sensitive than spirometry, which is currently used for surveillance and detection of BOS. We aimed to examine the feasibility of performing surveillance N2MBW in children post-HSCT, and in an exploratory analysis, determine if LCI2.5 led to earlier detection of BOS when compared to spirometric indices. Participants aged 5 to 17 years were recruited prior to receiving HSCT into a prospective, single-center, feasibility study at the Royal Children's Hospital, Melbourne. N2MBW and spirometry were performed within the month prior to transplant and repeated at 3, 6, 9, and 12 months post-transplant. Data were also collected on the presence of graft-versus-host (GVHD) disease in any organ, including the lungs. Twenty-one (12 male) children with a mean age of 13.4 (range 9.2 to 17.1) years at recruitment participated in this study. Prior to HSCT, all participants had normal LCI2.5, while 16 (76%) demonstrated normal forced expiratory volume in 1 second (FEV1). Ninety-nine percent of N2MBW tests were technically acceptable, compared with 66% of spirometry tests. Three participants developed BOS, while 2 participants died of other respiratory complications. At 6 and 12 months post-transplant, the BOS group had increases in LCI2.5 ranging from 3 to 5 units and mean reductions in FEV1 % predicted of 40% to 53% relative to pre HSCT values, respectively. In those who developed BOS, post-HSCT LCI2.5 values were significantly worse when compared with the no BOS group (P < .001). Relative changes in LCI2.5 and FEV1 were both predictive of BOS at 6 months post HSCT. This study demonstrates that N2MBW is a more feasible test compared with spirometry in children post HSCT. However, in an exploratory analysis, LCI2.5 did not lead to earlier detection of BOS, when compared to spirometry.

Restrictive allograft dysfunction rather than bronchiolitis obliterans syndrome had a major impact on the overall survival after living-donor lobar lung transplantation.

PURPOSE: Chronic lung allograft dysfunction (CLAD) is a known long-term fatal disorder after lung transplantation. In this study, we evaluated the CLAD classification of the International Society for Heart and Lung Transplantation (ISHLT) for living-donor lobar lung transplantation (LDLLT). METHODS: We conducted a single-center retrospective review of data from 73 patients who underwent bilateral LDLLT between 1998 and 2019. Factors related to opacity on computed tomography (CT) and restriction on pulmonary function tests (PFTs) were also analyzed. RESULTS: Overall, 26 (36%) patients were diagnosed with CLAD, including restrictive allograft syndrome (RAS), n = 10 (38.5%); bronchiolitis obliterans syndrome (BOS), n = 8 (30.8%); mixed, n = 1 (3.8%); undefined, n = 2 (7.7%); and unclassified, n = 5 (19.2%). The 5-year survival rate after the CLAD onset was 60.7%. The survival of patients with BOS was significantly better than that of patients with RAS (p = 0.012). In particular, patients with restriction on PFT had a significantly worse survival than those without restriction (p = 0.001). CONCLUSIONS: CLAD after bilateral LDLLT does not have a major impact on the recipient survival, especially in patients with BOS. Restriction on PFT may predict a particularly poor prognosis in patients with CLAD after bilateral LDLLT.

Impulse Oscillometry Versus Spirometry to Detect Bronchiolitis Obliterans Syndrome in Bilateral Lung Transplant Recipients: A Prospective Diagnostic Study.

BACKGROUND: Chronic lung allograft dysfunction (CLAD), and especially bronchiolitis obliterans syndrome (BOS), remain dominant causes of morbidity and mortality after lung transplantation. Interest is growing in the forced oscillation technique, of which impulse oscillometry (IOS) is a form, as a tool to improve our understanding of these disorders. However, data remain limited and no longitudinal studies have been published, meaning there is no information regarding any capacity IOS may have for the early detection of CLAD. METHODS: We conducted a prospective longitudinal study enrolling a consecutive sample of adult bilateral lung transplant recipients with healthy lung allografts or CLAD and performed ongoing paired IOS and spirometry tests on a clinically determined basis. We assessed for correlations between IOS and spirometry and examined any predictive value either modality may hold for the early detection of BOS. RESULTS: We enrolled 91 patients and conducted testing for 43 mo, collecting 558 analyzable paired IOS and spirometry tests, with a median of 9 tests per subject (interquartile range, 5-12) and a median testing interval of 92 d (interquartile range, 62-161). Statistically significant moderate-to-strong correlations were demonstrated between all IOS parameters and spirometry, except resistance at 20 Hz, which is a proximal airway measure. No predictive value for the early detection of BOS was found for IOS or spirometry. CONCLUSIONS: This study presents the first longitudinal data from IOS after lung transplantation and adds considerably to the growing literature, showing unequivocal correlations with spirometry but failing to demonstrate a predictive value for BOS.

Risk factors and prediction models for bronchiolitis obliterans after severe adenoviral pneumonia.

Severe adenoviral pneumonia (SAP) can cause post-infectious bronchiolitis obliterans (PIBO) in children. We aimed to investigate the relevant risk factors for PIBO and develop a predictive nomogram for PIBO in children with SAP. This prospective study analysed the clinical data of hospitalised children with SAP and categorised them into the PIBO and non-PIBO groups. Least absolute shrinkage and selection operator (LASSO) regressions were applied to variables that exhibited significant intergroup differences. Logistic regression was adopted to analyse the risk factors for PIBO. Additionally, a nomogram was constructed, and its effectiveness was assessed using calibration curves, C-index, and decision curve analysis. A total of 148 hospitalised children with SAP were collected in this study. Among them, 112 achieved favourable recovery, whereas 36 developed PIBO. Multivariable regression after variable selection via LASSO revealed that aged < 1 year (OR, 2.38, 95% CI, 0.82-6.77), admission to PICU (OR, 24.40, 95% CI, 7.16-105.00), long duration of fever (OR, 1.16, 95% CI, 1.04-1.31), and bilateral lung infection (OR, 8.78, 95% CI, 1.32-195.00) were major risk factors for PIBO. The nomogram model included the four risk factors: The C-index of the model was 0.85 (95% CI, 0.71-0.99), and the area under the curve was 0.85 (95% CI, 0.78-0.92). The model showed good calibration with the Hosmer-Lemeshow test (χ2 = 8.52, P = 0.38) and was useful in clinical settings with decision curve analysis. CONCLUSION: Age < 1 year, PICU admission, long fever duration, and bilateral lung infection are independent risk factors for PIBO in children with SAP. The nomogram model may aid clinicians in the early diagnosis and intervention of PIBO. WHAT IS KNOWN: • Adenoviruses are the most common pathogens associated with PIBO. • Wheezing, tachypnoea, hypoxemia, and mechanical ventilation are the risk factors for PIBO. WHAT IS NEW: • Age < 1 year, admission to PICU, long duration of fever days, and bilateral lung infection are independent risk factors for PIBO in children with SAP. • A prediction model presented as a nomogram may help clinicians in the early diagnosis and intervention of PIBO.

Postinfectious bronchiolitis obliterans in children: case series at a pediatric hospital in Peru.

BACKGROUND: Postinfectious bronchiolitis obliterans is a rare lung disease; there are limited reports in South America. CASE REPORT: We report 10 patients with this disease diagnosed at the Instituto Nacional de Salud del Niño-Breña (Lima-Peru). The median age at diagnosis was 19 months and all patients had a history of severe acute respiratory infection. The most frequent symptoms were cough, respiratory distress, wheezing, and hypoxemia. The mosaic attenuation pattern was the most frequent on the tomography. All the patients had positive serology for adenovirus. The treatment received was methylprednisolone pulses, azithromycin, hydroxychloroquine, and inhaled corticosteroids. No patient died during the follow-up. CONCLUSIONS: In previously healthy children with a history of severe acute respiratory infection and persistent bronchial obstructive symptoms, the diagnosis of postinfectious bronchiolitis obliterans should be considered. This is the first report in Peru with a therapeutic regimen adapted to our institution.

INTRODUCCIÓN: La bronquiolitis obliterante postinfecciosa es una enfermedad pulmonar poco frecuente; existen limitados reportes en Sudamérica. CASO CLÍNICO: En esta serie se reportan 10 pacientes con esta enfermedad diagnosticados en el Instituto Nacional de Salud del Niño-Breña (Lima-Perú). La mediana de edad al diagnóstico fue de 19 meses. Todos los pacientes presentaron el antecedente de infección respiratoria aguda grave. Los síntomas más frecuentes fueron tos, dificultad respiratoria, sibilancias e hipoxemia; el patrón de atenuación en mosaico fue la característica más frecuente en la tomografía. Todos tenían serología positiva para adenovirus. Se administró tratamiento con pulsos de metilprednisolona, azitromicina, hidroxicloroquina y corticoides inhalados. Ningún paciente falleció durante el seguimiento. CONCLUSIONES: En los niños previamente sanos con antecedente de infección respiratoria aguda grave y sintomatología obstructivo bronquial persistente se debe considerar el diagnóstico de bronquiolitis obliterante postinfecciosa. Este es el primer reporte en Perú con un régimen terapéutico adaptado a nuestra institución.

Murine Intrapulmonary Tracheal Transplantation: A Model for Investigating Obliterative Airway Disease After Lung Transplantation.

Murine intrapulmonary tracheal transplantation (IPTT) is used as a model of obliterative airway disease (OAD) following lung transplantation. Initially reported by our team, this model has gained use in the study of OAD due to its high technical reproducibility and suitability for investigating immunological behaviors and therapeutic interventions. In the IPTT model, a rodent tracheal graft is directly inserted into the recipient's lung through the pleura. This model is distinct from the heterotopic tracheal transplantation (HTT) model, wherein grafts are transplanted into subcutaneous or omental sites, and from the orthotopic tracheal transplantation (OTT) model in which the donor trachea replaces the recipient's trachea. Successful implementation of the IPTT model requires advanced anesthetic and surgical skills. Anesthetic skills include endotracheal intubation of the recipient, setting appropriate ventilatory parameters, and appropriately timed extubation after recovery from anesthesia. Surgical skills are essential for precise graft placement within the lung and for ensuring effective sealing of the visceral pleura to prevent air leakage and bleeding. In general, the learning process takes approximately 2 months. In contrast to the HTT and OTT models, in the IPTT model, the allograft airway develops airway obliteration in the relevant lung microenvironment. This allows investigators to study lung-specific immunological and angiogenic processes involved in airway obliteration after lung transplantation. Furthermore, this model is also unique in that it exhibits tertiary lymphoid organs (TLOs), which are also seen in human lung allografts. TLOs are comprised of T and B cell populations and characterized by the presence of high endothelial venules that direct immune cell recruitment; therefore, they are likely to play a crucial role in graft acceptance and rejection. We conclude that the IPTT model is a useful tool for studying intrapulmonary immune and profibrotic pathways involved in the development of airway obliteration in the lung transplant allograft.

Prognostic Value of Chest CT Findings at BOS Diagnosis in Lung Transplant Recipients.

BACKGROUND: Bronchiolitis obliterans syndrome (BOS) after lung transplantation is characterized by fibrotic small airway remodeling, recognizable on high-resolution computed tomography (HRCT). We studied the prognostic value of key HRCT features at BOS diagnosis after lung transplantation. METHODS: The presence and severity of bronchiectasis, mucous plugging, peribronchial thickening, parenchymal anomalies, and air trapping, summarized in a total severity score, were assessed using a simplified Brody II scoring system on HRCT at BOS diagnosis, in a cohort of 106 bilateral lung transplant recipients transplanted between January 2004 and January 2016. Obtained scores were subsequently evaluated regarding post-BOS graft survival, spirometric parameters, and preceding airway infections. RESULTS: A high total Brody II severity score at BOS diagnosis (P = 0.046) and high subscores for mucous plugging (P = 0.0018), peribronchial thickening (P = 0.0004), or parenchymal involvement (P = 0.0121) are related to worse graft survival. A high total Brody II score was associated with a shorter time to BOS onset (P = 0.0058), lower forced expiratory volume in 1 s (P = 0.0006) forced vital capacity (0.0418), more preceding airway infections (P = 0.004), specifically with Pseudomonas aeruginosa (P = 0.002), and increased airway inflammation (P = 0.032). CONCLUSIONS: HRCT findings at BOS diagnosis after lung transplantation provide additional information regarding its underlying pathophysiology and for future prognosis of graft survival.

Monitoring regulatory T cells as a prognostic marker in lung transplantation.

Lung transplantation is the major surgical procedure, which restores normal lung functioning and provides years of life for patients suffering from major lung diseases. Lung transplant recipients are at high risk of primary graft dysfunction, and chronic lung allograft dysfunction (CLAD) in the form of bronchiolitis obliterative syndrome (BOS). Regulatory T cell (Treg) suppresses effector cells and clinical studies have demonstrated that Treg levels are altered in transplanted lung during BOS progression as compared to normal lung. Here, we discuss levels of Tregs/FOXP3 gene expression as a crucial prognostic biomarker of lung functions during CLAD progression in clinical lung transplant recipients. The review will also discuss Treg mediated immune tolerance, tissue repair, and therapeutic strategies for achieving in-vivo Treg expansion, which will be a potential therapeutic option to reduce inflammation-mediated graft injuries, taper the toxic side effects of ongoing immunosuppressants, and improve lung transplant survival rates.

Efficacy of inhaled tiotropium add-on to budesonide/formoterol in patients with bronchiolitis obliterans developing after hematopoietic stem cell transplantation.

BACKGROUND: Bronchiolitis obliterans syndrome (BOS) is the lung manifestation of chronic graft-versus-host disease after hematopoietic stem cell transplantation (HSCT). We assessed whether inhaled tiotropium add-on to the combination regimen including budesonide/formoterol improve pulmonary function and the chronic obstructive pulmonary disease assessment test (CAT) scores in patients with BOS. METHODS: Post-HSCT patients diagnosed as BOS in Seoul St. Mary's Hospital were reviewed retrospectively. Patients defined as BOS and treated with budesonide/formoterol/tiotropium combination therapy after budesonide/formoterol therapy from January 2011 to June 2019 were enrolled. RESULTS: Total of 86 patients were evaluated. After tiotropium add-on, the absolute FEV1 increased significantly from 1.47 ± 0.49 to 1.53 ± 0.57 L (p = 0.023) and the % predicted FEV1 from 45.0 ± 12.8 to 46.8 ± 14.5% (p = 0.031). The % predicted DLCO increased significantly after tiotropium add-on (from 61.6 ± 16.7 to 64.3 ± 16.3%, p = 0.028). Among 56 patients with complete CAT scores, no significant change was present in total CAT scores. In all, 30 of the 72 patients (41.7%) evidenced FEV1 increases > 100 mL, and 20 of 56 patients (35.7%) had CAT score decreases of ≥ 2 points. When the FEV1 and CAT scores were combined, the overall response rate to tiotropium add-on was 56.2% (41/73). The response group evidenced a significantly greater FVC increase, and a significant decrease in the RV/TLC ratio compared to the no-response group. CONCLUSIONS: Inhaled tiotropium add-on to combination budesonide/formoterol significantly improved lung function, but not respiratory symptoms, in patients with post-HSCT BOS.

Environmental and occupational bronchiolitis obliterans: new reality.

Patients diagnosed with environmental/occupational bronchiolitis obliterans (BO) over the last 2 decades often present with an indolent evolution of respiratory symptoms without a history of high-level, acute exposure to airborne toxins. Exertional dyspnea is the most common symptom and standard clinical and radiographic evaluation can be non-diagnostic. Lung biopsies often reveal pathological abnormalities affecting all distal lung compartments. These modern cases of BO typically exhibit the constrictive bronchiolitis phenotype of small airway remodeling, along with lymphocytic inflammation. In addition, hypertensive-type remodeling of intrapulmonary vasculature, diffuse fibroelastosis of alveolar tissue, and fibrous thickening of visceral pleura are frequently present. The diagnosis of environmental/occupational BO should be considered in patients who present with subacute onset of exertional dyspnea and a history compatible with prolonged or recurrent exposure to environmental toxins. Important areas for future studies include development of less invasive diagnostic approaches and testing of novel agents for disease prevention and treatment.

Collagen Type IV Alpha 5 Chain in Bronchiolitis Obliterans Syndrome After Lung Transplant: The First Evidence.

INTRODUCTION: Bronchiolitis obliterans syndrome (BOS) is the most common form of CLAD and is characterized by airflow limitation and an obstructive spirometry pattern without parenchymal opacities. The protein signature of BOS lesions concerns extracellular matrix organization and aberrant basement membrane composition. In this pilot study, we investigated the presence of COL4A5 in the serum of patients with BOS. METHODS: 41 patients who had undergone LTX were enrolled. Of these, 27 developed BOS and 14 (control group) were considered stable at the time of serum sampling. Of BOS patients, serum samples were analysed at the time of BOS diagnosis and before the clinical diagnosis (pre-BOS). COL4A5 levels were detected through the ELISA kit. RESULTS: Serum concentrations of COL4A5 were higher in pre-BOS than in stable patients (40.5 ± 13.9 and 24.8 ± 11.4, respectively, p = 0.048). This protein is not influenced by comorbidities, such as acute rejection or infections, or by therapies. Survival analysis also reveals that a higher level of COL4A5 was also associated with less probability of survival. Our data showed a correlation between concentrations of COL4A5 and FEV1 at the time of diagnosis of BOS. CONCLUSION: Serum concentrations of COL4A5 can be considered a good prognostic marker due to their association with survival and correlation with functional parameters.

Insight on immune cells in rejection and infection postlung transplant.

OBJECTIVE: The aim of this study is to provide a concise overview of the role of immune cells in rejection and infection after lung transplantation. METHODS: Based on previous clinical and basic studies, the role of various types of immune cells in the development of rejection and infection after lung transplantation is summarized. RESULTS: Immune cell functional status is strongly associated with common complications after lung transplantation, such as primary graft dysfunction, infection and occlusive bronchitis syndrome. Targeted balancing of immune cell tolerance and rejection is an important tool for successful lung transplantation. CONCLUSION: A comprehensive understanding of immune cell function and the mechanisms that balance immune tolerance and immune rejection may be a crucial factor in improving survival after lung transplantation.