Maintenance azithromycin therapy for bronchiolitis obliterans syndrome: results of a pilot study

Immunomodulatory Effects of Macrolides Considering Evidence from Human and Veterinary Medicine

Macrolide antimicrobial agents have been in clinical use for more than 60 years in both human and veterinary medicine. The discovery of the non-antimicrobial properties of macrolides and the effect of immunomodulation of the inflammatory response has benefited patients with chronic airway diseases and impacted morbidity and mortality. This review examines the evidence of antimicrobial and non-antimicrobial properties of macrolides in human and veterinary medicine with a focus toward veterinary macrolides but including important and relevant evidence from the human literature. The complete story for these complex and important molecules is continuing to be written.

Effect of azithromycin on bronchiolitis obliterans syndrome in posttransplant recipients: A systematic review and meta-analysis

BACKGROUND

Bronchiolitis obliterans syndrome (BOS) is a devastating complication that occurs after transplantation. Although azithromycin is currently used for the treatment of BOS, the evidence is sparse and controversial. The aim of this meta-analysis is to evaluate the effects of azithromycin on forced expiratory volume in 1 second (FEV1) and patient's survival.

METHODS

PubMed, Embase, Cochrane library, Web of Science databases, and the ClinicalTrials.gov registry were systematically searched from inception until December 2020 for relevant original research articles. Random-effects models were used to calculate pooled-effect estimates.

RESULTS

Searches identified 15 eligible studies involving 694 participants. For FEV1 (L), there was a significant increase after short-term (≤12 weeks; P = .00) and mid-term (12-24 weeks; P = .01) administration of azithromycin. For FEV1 (%) compared to baseline, there was a significant increase after short-term (≤12 weeks) administration of azithromycin (P = .02), while there were no statistically significant differences in the medium and long term. When pooled FEV1% was predicted, it exhibited a similar trend to FEV1 (%) compared to baseline. In addition, we discovered that azithromycin reduced the risk of death (hazard ratio = 0.26; 95% confidence interval = 0.17 to 0.40; P = .00) in patients with BOS post-lung transplantation.

CONCLUSIONS

Azithromycin therapy is both effective and safe for lung function improvement in patients with posttransplant BOS after the short- and medium-term administration. Additionally, it has been demonstrated a significant survival benefit among patients with BOS post-lung transplant. Higher quality randomized controlled trials and more extensive prospective cohort studies are needed to confirm the effect of azithromycin on patients with posttransplant BOS.

Pharmacotherapy of chronic lung allograft dysfunction post lung transplantation

Chronic lung allograft dysfunction (CLAD) remains the primary cause of death in lung transplant recipients (LTRs) in spite of improvements in immunosuppression management. Despite advances in knowledge regarding the pathogenesis of CLAD, treatments that are currently available are usually ineffective and delay progression of disease at best. There are currently no evidence-based guidelines for the optimal treatment of CLAD, and management varies widely across transplant centers. Additionally, there are minimal publications available to summarize data for currently available therapies and outcomes in LTRs. We identified the major domains of the medical management of CLAD and conducted a comprehensive search of PubMed and Embase databases to identify articles published from inception to December 2021 related to CLAD in LTRs. Studies published in English pertaining to the pharmacologic prevention and treatment of CLAD were included; highest priority was given to prospective, randomized, controlled trials if available. Prospective observational and retrospective controlled trials were prioritized next, followed by retrospective uncontrolled studies, case series, and finally case reports if the information was deemed to be pertinent. Reference lists of qualified publications were also reviewed to find any other publications of interest that were not found on initial search. In the absence of literature published in the aforementioned databases, additional articles were identified by reviewing abstracts presented at the International Society for Heart and Lung Transplantation and American Transplant Congress annual meetings between 2010-2021. This document serves to provide a comprehensive review of the literature and considerations for the prevention and medical management of CLAD. This article is protected by copyright. All rights reserved.

Bronchiolitis obliterans syndrome after lung or haematopoietic stem cell transplantation: current management and future directions

Bronchiolitis obliterans syndrome (BOS) may develop after either lung or haematopoietic stem cell transplantation (HSCT), with similarities in histopathological features and clinical manifestations. However, there are differences in the contributory factors and clinical trajectories between the two conditions. BOS after HSCT occurs due to systemic graft-versus-host-disease (GVHD), whereas BOS after lung transplantation is limited to the lung allograft. BOS diagnosis after HSCT is more challenging, as the lung function decline may occur due to extrapulmonary GVHD, causing sclerosis or inflammation in the fascia or muscles of the respiratory girdle. Treatment is generally empirical with no established effective therapies. This review provides rare insights and commonalities of both conditions, that are not well elaborated elsewhere in contemporary literature, and highlights the importance of cross disciplinary learning from experts in other transplant modalities. Treatment algorithms for each condition are presented, based on the published literature and consensus clinical opinion. Immunosuppression should be optimised, and other conditions or contributory factors treated where possible. When initial treatment fails, the ultimate therapeutic option is lung transplantation (or re-transplantation in the case of BOS after lung transplantation) in carefully selected candidates. Novel therapies under investigation include aerosolised liposomal cyclosporine, Janus kinase inhibitors, antifibrotic therapies, and (in patients with BOS after lung transplantation) B-cell–directed therapies. Effective novel treatments that have a tangible impact on survival and thereby avoid the need for lung transplantation or re-transplantation are urgently required.

Management of chronic rejection after lung transplantation

Outcomes after lung transplantation are limited by chronic lung allograft dysfunction (CLAD). The incidence of CLAD is high, and its clinical course tends to be progressive over time, culminating in graft failure and death. Indeed, CLAD is the leading cause of death beyond the first year after lung transplantation. Therapy for CLAD has been limited by a lack of high-quality studies to guide management. In this review, we will discuss the diagnosis of CLAD in light of the recent changes to definitions and will discuss the current clinical evidence available for treatment. Recently, the diagnosis of CLAD has been subdivided into bronchiolitis obliterans syndrome (BOS) and restrictive allograft syndrome (RAS). The current evidence for treatment of CLAD mainly revolves around treatment of BOS with more limited data existing for RAS. The best supported treatment to date for CLAD is the macrolide antibiotic azithromycin which has been associated with a small improvement in lung function in a minority of patients. Other therapies that have more limited data include switching immunosuppression from cyclosporine to tacrolimus, fundoplication for gastroesophageal reflux, montelukast, extracorporeal photopheresis (ECP), aerosolized cyclosporine, cytolytic anti-lymphocyte therapies, total lymphoid irradiation (TLI) and the antifibrotic agent pirfenidone. Most of these treatments are supported by case series and observational studies. Finally, we will discuss the role of retransplantation for CLAD.

Immunosuppression in Lung Transplantation

Immunosuppression in lung transplantation is an area devoid of robust clinical data. This chapter will review the history of immunosuppression in lung transplantation. Additionally, it will evaluate the three classes of induction, maintenance, and rescue immunosuppression in detail. Induction immunosuppression in lung transplantation aims to decrease incidence of lung allograft rejection, however infectious risk must be considered when determining if induction is appropriate and which agent is most favorable. Similar to other solid organ transplant patient populations, a multi-drug approach is commonly prescribed for maintenance immunosuppression to minimize single agent drug toxicities. Emphasis of this review is placed on key medication considerations including dosing, adverse effects, and drug interactions. Clinical considerations will be reviewed per drug class given available literature. Finally, acute cellular, antibody mediated, and chronic rejection are reviewed.

Chronic Lung Allograft Dysfunction: Evolving Concepts and Therapies

The primary factor that limits long-term survival after lung transplantation is chronic lung allograft dysfunction (CLAD). CLAD also impairs quality of life and increases the costs of medical care. Our understanding of CLAD continues to evolve. Consensus definitions of CLAD and the major CLAD phenotypes were recently updated and clarified, but it remains to be seen whether the current definitions will lead to advances in management or impact care. Understanding the potential differences in pathogenesis for each CLAD phenotype may lead to novel therapeutic strategies, including precision medicine. Recognition of CLAD risk factors may lead to earlier interventions to mitigate risk, or to avoid risk factors all together, to prevent the development of CLAD. Unfortunately, currently available therapies for CLAD are usually not effective. However, novel therapeutics aimed at both prevention and treatment are currently under investigation. We provide an overview of the updates to CLAD-related terminology, clinical phenotypes and their diagnosis, natural history, pathogenesis, and potential strategies to treat and prevent CLAD.

End-Stage Respiratory Failure Secondary to Bronchiolitis Obliterans Syndrome Induced by Toxic Epidermal Necrosis, Also Known as Lyell Syndrome: A Case Report

BACKGROUND

Stevens-Johnson syndrome (SJS) and toxic epidermal necrolysis (TEN) are rare but serious dermatologic diseases. They can be associated with systemic manifestations such as bronchiolitis obliterans syndrome (BOS). SJS/TEN-induced BOS is associated with a poor prognosis, and no guidelines exist regarding its management. Several case reports have described the association between SJS/TEN and BOS, with few patients undergoing lung transplantation as a last resort therapy. Unfortunately, in the published reports, none of the transplanted patients were observed for a long period of time after the transplantation; therefore, the long-term mortality as well as the risk of recurrence of BOS could not be inferred from these reports.

CASE REPORT

We present the case of a young patient diagnosed with SJS complicated by BOS and end-stage respiratory failure refractory to corticosteroid therapy. She underwent bilateral lung transplantation with an outstanding outcome at 5-year follow-up.

CONCLUSION

SJS/TEN-induced BOS might have a favorable evolution and long-term outcomes following lung transplantation. However, prospective studies are needed to confirm this finding.

Desensitization and management of allograft rejection

PURPOSE OF REVIEW

Chronic lung allograft dysfunction (CLAD) limits the success of lung transplantation. Among the risk factors associated with CLAD, we recognize pretransplant circulating antibodies against the human leukocyte antigens (HLA), acute cellular rejection (ACR) and antibody-mediated rejection (AMR). This review will summarize current data surrounding management of desensitization, ACR, AMR, and CLAD.

RECENT FINDINGS

Strategies in managing in highly sensitized patients waiting for lung transplant include avoidance of specific HLA antigens and reduction of circulating anti-HLA antibodies at time of transplant. Several multimodal approaches have been studied in the treatment of AMR with a goal to clear circulating donor-specific antibodies (DSAs) and to halt the production of new antibodies. Different immunosuppressive strategies focus on influence of the host immune system, particularly T-cell responses, in order to prevent ACR and the progression of CLAD.

SUMMARY

The lack of significant evidence and consensus limits to draw conclusion regarding the impact of specific immunosuppressive regimens in the management of HLA antibodies, ACR, and CLAD. Development of novel therapeutic agents and use of multicenter randomized clinical trials will allow to better define patient-specific treatments and improve the length and quality of life of lung transplant recipients.

Twelve-month effects of everolimus on renal and lung function in lung transplantation: differences in chronic lung allograft dysfunction phenotypes

Background:

Chronic lung allograft dysfunction (CLAD), a complication affecting the survival of lung transplanted patients, includes two clinical phenotypes: bronchiolitis obliterans syndrome (BOS) and restrictive allograft syndrome (RAS). Everolimus is used in CLAD because of its antiproliferative mechanism. In lung transplant patients treated with everolimus, the clinical course of renal and lung function has not yet been assessed systematically in CLAD, BOS and RAS patients for more than 6 months.

Methods:

We retrospectively evaluated the 12-month follow-up of renal and lung function of lung-transplanted patients switched to everolimus and evaluated the reduction in immunosuppressant dosage (ISD) and mortality. Subgroups were based on indication for everolimus treatment: CLAD and non-CLAD patients, BOS and RAS among CLAD patients.

Results:

We included 26 patients, 17 with CLAD (10 BOS, seven RAS). After 1 year from the everolimus switch, we observed renal function improvement (serum creatinine −17%, estimated glomerular filtration rate +24%) and stable pulmonary function [forced expiratory volume in the first second (FEV₁) −0.5%, forced vital capacity (FVC) +0.05%]. RAS patients had progressive functional loss, whereas BOS patients had FEV₁ improvement and FVC stability. All-cause mortality was higher in the CLAD versus non-CLAD group (41% versus 11%), without differences between BOS and RAS patients (p > 0.05). All patients had significant and persistent ISD reduction.

Conclusion:

Lung transplant patients treated with everolimus had improvements in renal function and reduced ISD. We observed sustained improvements in lung function for CLAD related to BOS subgroup results, whereas RAS confirmed the 1-year worsening functional trend. Data seem to suggest one more piece of the puzzle in CLAD phenotyping.

Noninvasive methods for detection of chronic lung allograft dysfunction in lung transplantation

Lung transplantation (LTx) is the only therapeutic option for end-stage lung diseases. Chronic lung allograft dysfunction (CLAD), which manifests as airflow restriction and/or obstruction, is the primary factor limiting the long-term survival of patients after surgery. According to histopathological and radiographic findings, CLAD comprises two phenotypes, bronchiolitis obliterans syndrome and restrictive allograft syndrome. Half of all lung recipients will develop CLAD in 5 years, and this rate may increase up to 75% 10 years after surgery owing to the paucity in accurate and effective early detection and treatment methods. Recently, many studies have presented noninvasive methods for detecting CLAD and improving diagnosis and intervention. However, the significance of accurately detecting CLAD remains controversial. We reviewed published studies that have presented noninvasive methods for detecting CLAD to highlight the current knowledge on clinical symptoms, spirometry, imaging examinations, and other methods to detect the disease.

Is bronchiectasis really a disease?

The definition of a disease requires that distinguishing signs and symptoms are present that are common, and that the constellation of signs and symptoms differentiate the condition from other causes. In bronchiectasis, anatomical changes, airways inflammation and airway infection are the distinguishing features that are common to this disease. However, bronchiectasis is a heterogenous disease: signs and symptoms are shared with other airway diseases, there are multiple aetiologies and certain phenotypes of bronchiectasis have distinct clinical and laboratory features that are not common to all people with bronchiectasis. Furthermore, response to therapeutic interventions in clinical trials is not uniform. The concept of bronchiectasis as a treatable trait has been suggested, but this may be too restrictive in view of the heterogeneity of bronchiectasis. It is our opinion that bronchiectasis should be defined as a disease in its own right, but one that shares several pathophysiological features and "treatable traits" with other airway diseases. These traits define the large heterogeneity in the pathogenesis and clinical features and suggest a more targeted approach to therapy.

Imatinib melylate as second-line treatment of bronchiolitis obliterans after allogenic hematopoietic stem cell transplantation in children

BACKGROUND

The onset of bronchiolitis obliterans (BO) as a pulmonary manifestation of chronic graft vs host disease dramatically changes the prognosis of children undergoing allogeneic hematopoietic stem cell transplantation (allo-HSCT). This study aimed to evaluate the overall survival (OS) of children with BO treated with imatinib mesylate (IM).

METHODS

This study included children who underwent allo-HSCTs between January 2000 and December 2016.

RESULTS

Among 345 patients who underwent HSCTs, 293 were evaluable for BO and 26 (8.9%) developed BO. The cumulative incidence of BO was 4.8% (95% confidence interval [CI], 2.8-7.5) at 1 year and 7.7% (95% CI, 5.1-11.1) at 3 years after transplantation. In the group of HSCTs (n = 67) complicated by chronic GvHD (c-GVHD), the incidence rate of BO was 38.8%. In total, 96.1% of patients with BO had c-GvHD worse than moderate grade, which was present in 70.7% of patients without BO (P = .011). The mortality rates were 46.1% in the BO group and 27.4% in the group without BO. Half of the patients with BO (n = 13) received IM, and the overall response rate was 76.9%. Four years after HSCT, OS was 42.6% (95% CI, 18.2-65.3) in the group without IM and 83.3% (95% CI, 27.3-97.5) in the group with IM.

CONCLUSIONS

BO after HSCT in the pediatric population has a high incidence and mortality rate. In terms of overall response and tolerability, this study showed relevant improvements in the prognosis of children with BO after the introduction of IM. Further prospective studies among children are needed to confirm these results.

Postinfectious Bronchiolitis Obliterans in Children: Diagnostic Workup and Therapeutic Options: A Workshop Report

Bronchiolitis obliterans (BO) is a rare, chronic form of obstructive lung disease, often initiated with injury of the bronchiolar epithelium followed by an inflammatory response and progressive fibrosis of small airways resulting in nonuniform luminal obliteration or narrowing. The term BO comprises a group of diseases with different underlying etiologies, courses, and characteristics. Among the better recognized inciting stimuli leading to BO are airway pathogens such as adenovirus and mycoplasma, which, in a small percentage of infected children, will result in progressive fixed airflow obstruction, an entity referred to as postinfectious bronchiolitis obliterans (PIBO). The present knowledge on BO in general is reasonably well developed, in part because of the relatively high incidence in patients who have undergone lung transplantation or bone marrow transplant recipients who have had graft-versus-host disease in the posttransplant period. The cellular and molecular pathways involved in PIBO, while assumed to be similar, have not been adequately elucidated. Since 2016, an international consortium of experts with an interest in PIBO assembles on a regular basis in Geisenheim, Germany, to discuss key areas in PIBO which include diagnostic workup, treatment strategies, and research fields.

Safety and Efficacy of Steroid Pulse Therapy for Acute Loss of FEV1 in Lung Transplant Recipients After Exclusion of Acute Cellular Rejection

BACKGROUND

The standard treatment of acute cellular rejection after lung transplantation (LTx) is a high-dose steroid pulse therapy. In our center, this therapy is also the standard of care for LTx recipients with acute loss of forced expiratory volume in 1 second (FEV₁), after excluding specific causes such as acute rejection on biopsy. The aim of this retrospective study was to evaluate the safety and efficacy of steroid pulse therapy.

METHODS

From 2015 to 2018, 33 consecutive patients (17 male patients, mean age ± SD, 50.5 ± 12.5 years) were included. All patients underwent routine examinations to exclude acute cellular rejection and other specific causes. FEV₁ was routinely measured after 5 days, and 1, 3, and 6 months. Positive response to steroid pulse therapy was defined by increase of FEV₁ > 10%.

RESULTS

The mean decrease ± SD from baseline in FEV₁ at the start of steroid pulse therapy was 380 ± 630 mL (P = .02). FEV₁ changed after 5 days by 170 ± 180 mL (P = .0007), and after 1 month by 140 ± 230 mL (P = .70), 3 months by -60 ± 240 mL (P = .15), and 6 months by -80 ± 290 mL (P = .73). A positive response was observed in 21% of patients after 3 months and 12% after 6 months. High bronchoalveolar lavage (BAL) eosinophil count correlated with a higher FEV₁ after steroid pulse therapy. Serious complications were observed in 4 out of 33 patients (12%) with 1 fatal event (pneumonia).

CONCLUSIONS

Only a minority of patients after LTx with loss of FEV₁ after exclusion of acute cellular rejection benefit from steroid pulse therapy. Patients with BAL eosinophilia are more likely to respond. However, severe complications were observed.

Clinical profile and course of children with postinfectious bronchiolitis obliterans from a tertiary care hospital

Background:

Postinfectious bronchiolitis obliterans (PIBO) is a chronic obstructive lung disease with scanty information in literature on etiology, clinical profile, treatment, and outcome.

Objective:

The objective of the study is to describe the clinical profile and course of children diagnosed with PIBO.

Methods:

A chart review of children below 18 years of age diagnosed as PIBO over the past 9 years was carried out. Details of clinical profile, laboratory investigations, imaging, treatment received, and outcome were recorded.

Results:

Eight children (boys 4) with PIBO were identified. Median (interquartile range [IQR]) age at the first episode of acute severe bronchiolitis such as illness and diagnosis of PIBO was 15 (6, 23.5) and 30 (16.5, 60) months, respectively, indicating a delay in diagnosis. The most common symptoms were recurrent episodes of cough (100%), fast breathing (100%), wheezing (87.5%), and fever (62.5%). Median (IQR) number of hospitalizations and episodes of antibiotic use prior to diagnosis were 2.5 (2, 5.5) and 2 (2, 4), respectively. Three (37.5%) children received mechanical ventilation during previous hospitalizations. Chest computed tomography revealed mosaic attenuation in 8 (100%), ground-glass opacities in 2 (25%), and bronchial wall thickening in 2 (25%). After diagnosis, 7 received oral steroids, 7 received hydroxychloroquine, 5 received azithromycin, and 2 received azathioprine. The median (IQR) duration of follow-up (n = 6) was 6 (1.5, 9.5) months. Median (IQR) number of pulmonary exacerbations in follow-up was 2 (1, 5).

Conclusion:

PIBO is still an under-recognized entity with substantial delay in diagnosis and unnecessary use of antibiotics. Clinical course with imaging findings may help to diagnose and manage this entity.

Long-term effect of azithromycin in bronchiolitis obliterans syndrome

Introduction

Azithromycin stabilises and improves lung function forced expiratory volume in one second (FEV₁) in lung transplantation patients with bronchiolitis obliterans syndrome (BOS). A post hoc analysis was performed to assess the long-term effect of azithromycin on FEV₁, BOS progression and survival .

Methods

Eligible patients recruited for the initial randomised placebo-controlled trial received open-label azithromycin after 3 months and were followed up until 6 years after inclusion (n=45) to assess FEV₁, BOS free progression and overall survival.

Results

FEV₁ in the placebo group improved after open-label azithromycin and was comparable with the treatment group by 6 months. FEV₁ decreased after 1 and 5 years and was not different between groups. Patients (n=18) with rapid progression of BOS underwent total lymphoid irradiation (TLI). Progression-free survival (log-rank test p=0.40) and overall survival (log-rank test p=0.28) were comparable. Survival of patients with early BOS was similar to late-onset BOS (log-rank test p=0.74).

Discussion

Long-term treatment with azithromycin slows down the progression of BOS, although the effect of TLI may affect the observed attenuation of FEV₁ decline. BOS progression and long-term survival were not affected by randomisation to the placebo group, given the early cross-over to azithromycin and possibly due to TLI in case of further progression. Performing randomised placebo-controlled trials in lung transplantation patients with BOS with a blinded trial duration is feasible, effective and safe.

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.

Type I collagen or gelatin stimulates mouse peritoneal macrophages to aggregate and produce pro-inflammatory molecules through upregulated ROS levels

BACKGROUND

Extracellular matrix (ECM) comprising the environments of multicellular society has a dynamic network structure. Collagen is one of the ubiquitous components of ECM. Collagen affects the inflammatory response by regulating the release of pro-inflammatory cytokines from cells. Gelatin, denatured collagen found temporally in tissues, is supposed to be pathophysiologically involved in tissue remodeling, inflammation caused by tissue damage. Previous reports indicate that, phorbol myristate (PMA)-stimulated human U937 (lymphoma cell line) cells that are often used as macrophage-like cells, show cell aggregations when cultured on type I collagen (col I) or gelatin-coated dishes, accompanying the changes of production and release of proinflammatory factors. However, it still remains to be examined whether collagen and gelatin affects normal macrophages as well.

AIM

This study aims to investigate the effect of col. I, the main component of collagenous protein and its denatured product, gelatin, on mouse peritoneal macrophages (MPMs).

METHODS

MTT assay, flow cytometric analysis of ROS, biochemical detection of antioxidant levels, ELISA assay, and western blot were used.

RESULTS

MPMs formed multicellular aggregates on col. I - and gelatin-coated dishes with a concentration- and time-dependent manner. Further studies showed that the culture on col. I and gelatin up-regulated the protein expression and secretion of pro-inflammatory molecules such as IL-1β, TNFα and prostaglandin E₂ (PGE₂) in MPMs. The levels were higher in the cells on gelatin than those on col. I. ROS levels are significantly increased in the cells cultured on both col. I- and gelatin-coated dishes, accompanying decreased levels of antioxidant enzyme catalase (CAT) and anti-oxidant glutathione (GSH), and enhanced nuclear translocation of NF-κB.

CONCLUSION

Col I - or gelatin-coated culture induced the formation of multicellular aggregates and increased production of NF-κB-associated pro-inflammatory molecules in MPMs through up-regulation of ROS levels.

MRI-derived regional flow-volume loop parameters detect early-stage chronic lung allograft dysfunction

BACKGROUND

Chronic lung allograft dysfunction (CLAD) is a major cause for the low long-term survival rates after lung transplantation (LTx). Early detection of CLAD may enable providing medical treatment before a nonreversible graft dysfunction has occurred. MRI is advantageous to pulmonary function testing (PFT) in the ability to assess regional function changes, and thus have the potential in detecting very early stages of CLAD before changes in global forced expiratory volume during the first second (FEV1%) occur.

PURPOSE

To examine whether early stages of CLAD (diagnosed based on PFT values) could also be detected using MRI-derived parameters of regional flow-volume dynamics.

STUDY TYPE

Retrospective.

POPULATION

62 lung transplantation recipients were included in the study, 29 of which had been diagnosed with CLAD at various stages.

FIELD STRENGTH/SEQUENCE

MRI datasets were acquired with a 1.5T Siemens scanner using a spoiled gradient echo sequence.

ASSESSMENT

MRI datasets were retrospectively preprocessed and analyzed by a blinded radiologist according to the phase resolved functional lung MRI (PREFUL-MRI) approach, resulting in fractional ventilation (FV) maps and regional flow-volume loops (rFVL). FV- and rFVL-based parameters of regional lung ventilation were estimated.

STATISTICAL TESTS

Differences between groups were compared by Mann-Whitney U-test with a Bonferroni correction for multiple comparisons (n = 2).

RESULTS

rFVL-CC-based parameters discriminated significantly between the presence or absence of CLAD (P < 0.003).

DATA CONCLUSION

Using the contrast media-free PREFUL-MRI technique, parameters of ventilation dynamics and its regional heterogeneity were shown to be sensitive for the detection of early CLAD stages.

LEVEL OF EVIDENCE

3 TECHNICAL EFFICACY: Stage 3 J. Magn. Reson. Imaging 2019;50:1873-1882.

Diagnosis, Pathophysiology and Experimental Models of Chronic Lung Allograft Rejection

Chronic rejection is the Achilles heel of modern lung transplantation, characterized by a slow, progressive decline in allograft function. Clinically, this manifests as obstructive disease, restrictive disease, or a mixture of the 2 depending on the underlying pathology. The 2 major phenotypes of chronic rejection include bronchiolitis obliterans syndrome and restrictive allograft syndrome. The last decade of research has revealed that each of these phenotypes has a unique underlying pathophysiology which may require a distinct treatment regimen for optimal control. Insights into the intricate alloimmune pathways contributing to chronic rejection have been gained from both large and small animal models, suggesting directions for future research. In this review, we explore the pathological hallmarks of chronic rejection, recent insights gained from both clinical and basic science research, and the current state of animal models of chronic lung rejection.

Complications of Stem Cell Transplantation that Affect Infections in Stem Cell Transplant Recipients, with Analogies to Patients with Hematologic Malignancies

This article discusses the complications of hematopoietic stem cell transplantion (HSCT) that affect infections in HSCT recipients, with analogies to patients with hematologic malignancies. Mucositis, with mucosal barrier disruption, is common and increases the risk of gram-positive and anaerobic bacterial, and fungal infections, and can evolve to typhlitis. Engraftment syndrome; graft-versus-host disease, hepatic sinusoidal obstruction syndrome; and posterior reversible encephalopathy syndrome can affect the infectious potential either directly from organ dysfunction or indirectly from specific treatment. Pulmonary infections can predispose to life threatening complications including diffuse alveolar hemorrhage, idiopathic pulmonary syndrome, bronchiolitis obliterans syndrome, and bronchiolitis obliterans with organizing pneumonia.

Diagnosing and managing bronchiolitis obliterans in children

INTRODUCTION

Bronchiolitis obliterans (BO) is a chronic and irreversible obstructive lung disease leading to the obstruction and/or obliteration of the small airways. Three main BO entities are distinguished: post-infectious BO (PIBO); BO post lung transplantation; and BO after bone marrow transplantation (BMT) or hematopoietic stem cell transplantation (HSCT). All three entities are separate, however, there are similarities in histopathological characteristics and possibly in aspects of the development pathway. Areas covered: We review current evidence of bronchiolitis obliterans diagnosis and management in children. The diagnosis of BO is usually based on a combination of history, clinical and radiological findings, although lung biopsy and histopathology remain the gold standard approaches to confirm BO. Expert opinion: At present, we do not have a clear understanding of the mechanisms of the development of BO and lack strong evidence for treatment. Although most BO in children is post-infectious, most of the current evidence for treatment originates from studies analyzing BO in adult lung transplant and HSCT patients. BO management requires multidisciplinary approach and care in specialized centers.

[Prevent bacteria from communicating: Divide to cure]

Quorum Sensing (QS) is a communication system used by numerous bacteria to synchronize their behavior according to the cell density. In this way, bacteria secrete and sense small mediating molecules, called autoinducers (AI), which concentration increases in the environment proportionally to bacterial cell number. QS induces major physiological and phenotypic changes such as virulence induction and biofilm formation. Biofilm represents a physical barrier which shelters bacteria poorly sensitive to antimicrobial treatments and favors the apparition of resistance mechanisms. Disturbing QS is referred to as quorum quenching (QQ). This strategy is used by microorganisms themselves to prevent the development of specific group behaviors. Two strategies are mainly employed: the use of quorum sensing inhibitors (QSI) and of quorum quenching enzymes (QQE) that degrades AI. Many studies have been dedicated to identifying QSI (natural or synthetic) as well as QQE and demonstrating their anti-virulence and anti-biofilm effects on numerous bacterial species. Synergistic effects between QQ and traditional treatments such as antibiotherapy or with reemerging phage therapy have been put forward. The efficiency of numerous QSI and QQE was thereby demonstrated either with in vitro or in vivo animal models leading to the development of medical devices containing QSI and QQE to improve already existing treatments.

Combined treatment with sinomenine and acupuncture on collagen-induced arthritis through the NF-κB and MAPK signaling pathway

Sinomenine is a monomer extracted from the traditional Chinese medicine plant Sabia japonica, which possesses several pharmacological properties including prominent abirritation, mitigation, anti-inflammation, immune suppression, cough relief, stimulation of histamine release, decrease in blood pressure and antiarrhythmia. Sinomenine is clinically employed to treat rheumatic disease. To investigate the impact of combined sinomenine treatment with acupuncture on the progression of arthritis and explore the potential underlying molecular mechanisms, the present study analyzed a collagen-induced arthritis model. Results from the combined curative (CC) treatment group (combined treatment with sinomenine and acupuncture) demonstrated a decrease in volume changes and arthritis score changes within rat paws, and increased the overall body weight in arthritic rats. CC treatment significantly decreased tumor necrosis factor α, interleukin (IL)-6, IL-1β and IL-8 serum levels in arthritic rats. CC treatment significantly increased superoxide dismutase and inhibited malondialdehyde levels in arthritic rats. The protein expression of cyclooxygenase-2, inducible nitric oxide synthase, matrix metalloproteinase (MMP)2 and MMP9 in arthritic rats was suppressed owing to CC treatment. Finally, nuclear factor κB and phosphorylated p38 mitogen-activated protein kinase (MAPK) protein expression in arthritic rats were also suppressed following CC treatment. The results indicate that the combined treatment of sinomenine and acupuncture on collagen-induced arthritis takes effect through the nuclear factor κB and MAPK signaling pathway.

Azithromycin Fails to Prevent Accelerated Airway Obliteration in T-bet-/- Mouse Lung Allograft Recipients

BACKGROUND

Cellular and molecular mechanisms of acute and chronic lung allograft rejection have yet to be clearly defined, and obliterative bronchiolitis (OB) remains the primary limitation to survival in lung transplant recipients (LTRs). We have previously shown that T-bet-deficient recipients of full major histocompatibility complex (MHC)-mismatched, orthotopic left lung transplants develop accelerated obliterative airway disease (OAD) in the setting of acute cellular rejection characterized by robust alloimmune CD8⁺ interleukin (IL)-17 and interferon (IFN)-γ responses that are attenuated with neutralization of IL-17. Azithromycin has been shown to be beneficial in some LTRs with bronchiolitis obliterans syndrome/OB. Here, we evaluated the effects of azithromycin on rejection pathology and T-cell effector responses in T-bet^-/- recipients of lung transplants.

METHODS

Orthotopic left lung transplantation was performed in BALB/c → B6 wild type or BALB/c → B6 T-bet^-/- strain combinations as previously described. Mice treated with azithromycin received 10 mg/kg or 50 mg/kg subcutaneously daily. Lung allograft histopathology was analyzed at day 10 or day 21 post-transplantation, and neutrophil staining for quantification was performed using anti-myeloperoxidase. Allograft mononuclear cells were isolated at day 10 for T-cell effector cytokine response assessment using flow cytometry.

RESULTS

We show that while azithromycin significantly decreases lung allograft neutrophilia and CXCL1 levels and attenuates allospecific CD8⁺ IL-17 responses early post-transplantation, OAD persists in T-bet-deficient mice.

CONCLUSIONS

Our results indicate that lung allograft neutrophilia is not essential for the development of OAD in this model and suggest allospecific T-cell responses that remain despite marked attenuation of CD8⁺ IL-17 are sufficient for obliterative airway inflammation and fibrosis.

Interference in Bacterial Quorum Sensing: A Biopharmaceutical Perspective

Numerous bacteria utilize molecular communication systems referred to as quorum sensing (QS) to synchronize the expression of certain genes regulating, among other aspects, the expression of virulence factors and the synthesis of biofilm. To achieve this process, bacteria use signaling molecules, known as autoinducers (AIs), as chemical messengers to share information. Naturally occurring strategies that interfere with bacterial signaling have been extensively studied in recent years, examining their potential to control bacteria. To interfere with QS, bacteria use quorum sensing inhibitors (QSIs) to block the action of AIs and quorum quenching (QQ) enzymes to degrade signaling molecules. Recent studies have shown that these strategies are promising routes to decrease bacterial pathogenicity and decrease biofilms, potentially enhancing bacterial susceptibility to antimicrobial agents including antibiotics and bacteriophages. The efficacy of QSIs and QQ enzymes has been demonstrated in various animal models and are now considered in the development of new medical devices against bacterial infections, including dressings, and catheters for enlarging the therapeutic arsenal against bacteria.

Immunomodulatory Cell Therapy to Target Cystic Fibrosis Inflammation

Cystic fibrosis (CF) is associated with exaggerated and prolonged inflammation in the lungs, which contributes to lung injury, airway mucus obstruction, bronchiectasis, and loss of lung function. This hyperinflammatory phenotype appears to be caused by an imbalance between the pro- and antiinflammatory regulatory pathways, with heightened proinflammatory stimuli, a decreased counter-regulatory response, and reduced effectiveness of immune cell function and inflammatory resolution. Thus, therapies that can target this inflammatory environment would have a major impact on preventing the progression of lung disease. Because of the complex phenotype of CF inflammation, current antiinflammatory regimens have proven to be inadequate for the targeting of these multiple dysregulated pathways and effects. Several approaches using cell therapies have shown potential therapeutic benefit for the treatment of CF inflammation. This review provides an overview of the immune dysfunctions in CF and current therapeutic regimens; explores the field of cell therapy as a treatment for CF inflammation; and focuses on the various cell types used, their immunomodulatory functions, and the current approaches to mitigate the inflammatory response and reduce the long-term damage for patients with CF.

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.

Managing the oncologic patient with suspected pneumonia in the intensive care unit

INTRODUCTION

Solid cancer patients are frequently admitted in intensive care units for critical events. Improving survival rates in this setting is considered an achievable goal today. Respiratory failure is the main reason for admission, representing a primary target for research.

AREAS COVERED

This review presents a diagnostic and therapeutic algorithm for pneumonia and other severe respiratory events in the solid cancer population. It aims to increase awareness of the risk factors and the different etiologies in this changing scenario in which neutropenia no longer seems to be a decisive factor in poor outcome. Bacterial pneumonia is the leading cause, but opportunistic diseases and non-infectious etiologies, especially unexpected adverse effects of radiation, biological drugs and monoclonal antibodies, are becoming increasingly frequent. Options for respiratory support and diagnostics are discussed and indications for antibiotics in the management of pneumonia are detailed. Expert commentary: Prompt initiation of critical care to facilitate optimal decision-making in the management of respiratory failure, early etiological assessment and appropriate antibiotic therapy are cornerstones in management of severe pneumonia in oncologic patients.

Update in Chronic Lung Allograft Dysfunction

Chronic lung allograft dysfunction (CLAD) is the major limitation to posttransplant survival. This review highlights the evolving definition of CLAD, risk factors, treatment, and expected outcomes after the development of CLAD.

Chronic lung allograft dysfunction phenotypes and treatment

Chronic lung allograft dysfunction (CLAD) remains a major hurdle limiting long-term survival post lung transplantation. Given the clinical heterogeneity of CLAD, recently two phenotypes of CLAD have been defined [bronchiolitis obliterans syndrome (BOS) vs. restrictive allograft syndrome (RAS) or restrictive CLAD (rCLAD)]. BOS is characterized by an obstructive pulmonary function, air trapping on CT and obliterative bronchiolitis (OB) on histopathology, while RAS/rCLAD patients show a restrictive pulmonary function, persistent pleuro-parenchymal infiltrates on CT and pleuroparenchymal fibro-elastosis on biopsies. Importantly, the patients with RAS/rCLAD have a severely limited survival post diagnosis of 6-18 months compared to 3-5 years after BOS diagnosis. In this review, we will review historical evidence for this heterogeneity and we will highlight the clinical, radiological, histopathological characteristics of both phenotypes, as well as their risk factors. Treatment of CLAD remains troublesome, nevertheless, we will give an overview of different treatment strategies that have been tried with some success. Adequate phenotyping remains difficult but is clearly needed for both clinical and scientific purposes.

Microbiome in the pathogenesis of cystic fibrosis and lung transplant-related disease

Significant advances in culture-independent methods have expanded our knowledge about the diversity of the lung microbial environment. Complex microorganisms and microbial communities can now be identified in the distal airways in a variety of respiratory diseases, including cystic fibrosis (CF) and the posttransplantation lung. Although there are significant methodologic concerns about sampling the lung microbiome, several studies have now shown that the microbiome of the lower respiratory tract is distinct from the upper airway. CF is a disease characterized by chronic airway infections that lead to significant morbidity and mortality. Traditional culture-dependent methods have identified a select group of pathogens that cause exacerbations in CF, but studies using bacterial 16S rRNA gene-based microarrays have shown that the CF microbiome is an intricate and dynamic bacterial ecosystem, which influences both host immune health and disease pathogenesis. These microbial communities can shift with external influences, including antibiotic exposure. In addition, there have been a number of studies suggesting a link between the gut microbiome and respiratory health in CF. Compared with CF, there is significantly less knowledge about the microbiome of the transplanted lung. Risk factors for bronchiolitis obliterans syndrome, one of the leading causes of death, include microbial infections. Lung transplant patients have a unique lung microbiome that is different than the pretransplanted microbiome and changes with time. Understanding the host-pathogen interactions in these diseases may suggest targeted therapies and improve long-term survival in these patients.

How I treat bronchiolitis obliterans syndrome after hematopoietic stem cell transplantation

In past years, a diagnosis of bronchiolitis obliterans syndrome (BOS) after allogeneic hematopoietic cell transplant (HCT) conferred nearly universal mortality secondary to lack of consensus for diagnostic criteria, poorly understood disease pathogenesis, and very few studies of therapeutic or supportive care interventions. Recently, however, progress has been made in these areas: revised consensus diagnostic guidelines are now available, supportive care has improved, there is greater understanding of potential mechanisms of disease, and prospective trials are being conducted. This article describes these advances and provides suggestions to optimize therapy for patients with BOS after HCT.

Update on Chronic Lung Allograft Dysfunction

Chronic lung allograft dysfunction (CLAD) encompasses a range of pathologies that cause a transplanted lung to not achieve or maintain normal function. CLAD manifests as airflow restriction and/or obstruction and is predominantly a result of chronic rejection. Three distinct phenotypes of chronic rejection are now recognized: bronchiolitis obliterans, neutrophilic reversible allograft dysfunction, and restrictive allograft syndrome. Recent investigations have revealed that each phenotype has a unique pathology and histopathological findings, suggesting that treatment regimens should be tailored to the underlying etiology. CLAD is poorly responsive to treatment once diagnosed, and therefore the prevention of the factors that predispose a patient to develop CLAD is critically important. Small and large animal models have contributed significantly to our understanding of CLAD and more studies are needed to develop treatment regimens that are effective in humans.

Anti-inflammatory Properties of Macrolide Antibiotics

The use of macrolide antibiotics for other clinical uses outside of their antimicrobial capabilities has been questioned and theorized in both in vitro and animal studies. Several small clinical trials have shown that erythromycin, clarithromycin, and azithromycin possess anti-inflammatory characteristics in patients with respiratory diseases. To determine whether macrolide antibiotics possess this unique characteristic, data from controlled trials involving human subjects were extracted and analyzed. Conclusions from trials suggest that select macrolide antibiotics possess anti-inflammatory properties in patients with respiratory diseases who do not show evidence of a bacterial infection.

Fluticasone, Azithromycin, and Montelukast Treatment for New-Onset Bronchiolitis Obliterans Syndrome after Hematopoietic Cell Transplantation

Bronchiolitis obliterans syndrome (BOS) after allogeneic hematopoietic cell transplantation (HCT) is associated with high mortality. We hypothesized that inhaled fluticasone, azithromycin, and montelukast (FAM) with a brief steroid pulse could avert progression of new-onset BOS. We tested this in a phase II, single-arm, open-label, multicenter study (NCT01307462). Thirty-six patients were enrolled within 6 months of BOS diagnosis. The primary endpoint was treatment failure, defined as 10% or greater forced expiratory volume in 1 second decline at 3 months. At 3 months, 6% (2 of 36, 95% confidence interval, 1% to 19%) had treatment failure (versus 40% in historical controls, P < .001). FAM was well tolerated. Steroid dose was reduced by 50% or more at 3 months in 48% of patients who could be evaluated (n = 27). Patient-reported outcomes at 3 months were statistically significantly improved for Short-Form 36 social functioning score and mental component score, Functional Assessment of Cancer Therapies emotional well-being, and Lee symptom scores in lung, skin, mouth, and the overall summary score compared to enrollment (n = 24). At 6 months, 36% had treatment failure (95% confidence interval, 21% to 54%, n = 13 of 36, with 6 documented failures, 7 missing pulmonary function tests). Overall survival was 97% (95% confidence interval, 84% to 100%) at 6 months. These data suggest that FAM was well tolerated and that treatment with FAM and steroid pulse may halt pulmonary decline in new-onset BOS in the majority of patients and permit reductions in systemic steroid exposure, which collectively may improve quality of life. However, additional treatments are needed for progressive BOS despite FAM.

Prophylactic Azithromycin Therapy After Lung Transplantation: Post hoc Analysis of a Randomized Controlled Trial

Prophylactic azithromycin treatment has been demonstrated to improve freedom from bronchiolitis obliterans syndrome (BOS) 2 years after lung transplantation (LTx). In the current study, we re-evaluated the long-term effects of this prophylactic approach in view of the updated classification system for chronic lung allograft dysfunction (CLAD). A retrospective, intention-to-treat analysis of a randomized controlled trial comparing prophylactic treatment with placebo (n = 43) versus azithromycin (n = 40) after LTx was performed. Graft dysfunction (CLAD), graft loss (retransplantation, mortality), evolution of pulmonary function and functional exercise capacity were analyzed 7 years after inclusion of the last study subject. Following LTx, 22/43 (51%) patients of the placebo group and 11/40 (28%) patients of the azithromycin group ever developed CLAD (p = 0.043). CLAD-free survival was significantly longer in the azithromycin group (p = 0.024). No difference was present in proportion of obstructive versus restrictive CLAD between both groups. Graft loss was similar in both groups: 23/43 (53%) versus 16/40 (40%) patients (p = 0.27). Long-term pulmonary function and functional exercise capacity were significantly better in the azithromycin group (p < 0.05). Prophylactic azithromycin therapy reduces long-term CLAD prevalence and improves CLAD-free survival, pulmonary function, and functional exercise capacity after LTx.

Postinfectious bronchiolitis obliterans in children: lessons from bronchiolitis obliterans after lung transplantation and hematopoietic stem cell transplantation

Postinfectious bronchiolitis obliterans (PIBO) is an irreversible obstructive lung disease characterized by subepithelial inflammation and fibrotic narrowing of the bronchioles after lower respiratory tract infection during childhood, especially early childhood. Although diagnosis of PIBO should be confirmed by histopathology, it is generally based on history and clinical findings. Irreversible airway obstruction is demonstrated by decreased forced expiratory volume in 1 second with an absent bronchodilator response, and by mosaic perfusion, air trapping, and/or bronchiectasis on computed tomography images. However, lung function tests using spirometry are not feasible in young children, and most cases of PIBO develop during early childhood. Further studies focused on obtaining serial measurements of lung function in infants and toddlers with a risk of bronchiolitis obliterans (BO) after lower respiratory tract infection are therefore needed. Although an optimal treatment for PIBO has not been established, corticosteroids have been used to target the inflammatory component. Other treatment modalities for BO after lung transplantation or hematopoietic stem cell transplantation have been studied in clinical trials, and the results can be extrapolated for the treatment of PIBO. Lung transplantation remains the final option for children with PIBO who have progressed to end-stage lung disease.

[Gastro-esophageal reflux and chronic respiratory diseases]

Gastroesophageal reflux disease (GERD) frequently occurs in association with chronic respiratory diseases although the casual link is not always clear. Several pathophysiological and experimental factors are considered to support a role for GERD in respiratory disease. Conversely, respiratory diseases and bronchodilator treatment can themselves exacerbate GERD. When cough or severe asthma is being investigated, GERD does not need to be systematically looked for and a therapeutic test with proton pump inhibitors is not always recommended. pH impedance monitoring is now the reference diagnostic tool to detect non acid reflux, a form of reflux for which proton pump inhibitor treatment is ineffective. Recent data have shown a potential role of GERD in idiopathic pulmonary fibrosis and bronchiolitis obliterans following lung transplantation, leading to discussions about the place of surgery in this context. However, studies using pH impedance monitoring are still needed to better understand and manage the association between GERD and chronic respiratory diseases.