Chlamydia pneumoniae infection after lung transplantation

Early chest CT abnormalities to predict the subsequent occurrence of chronic lung allograft dysfunction

INTRODUCTION

Chronic lung allograft dysfunction (CLAD) can take two forms: bronchiolitis obliterans syndrome (BOS) or restrictive allograft syndrome (RAS). The aim was to determine if chest-CT abnormalities after lung transplantation (LTx) could predict CLAD before respiratory functional deterioration.

MATERIALS AND METHODS

This monocentric retrospective study analyzed consecutive patients who underwent LTx from January 2015 to December 2018. Initial CT post-LTx (CTi) and a follow-up CT at least 9 months post-LTx (CTf) were reviewed. CLAD was defined as a persistent respiratory functional decline (> 20% of basal FEV1) outside acute episode. A Cox regression was performed in univariate, then in multivariate analysis (including features with p < 0.01 in univariate or of clinical importance) to determine risk factors for CLAD. Subgroup analyses were made for BOS, RAS, and death.

RESULTS

Among 118 LTx patients (median (min-max) 47 (18-68) years), 25 developed CLAD during follow-up (19 BOS). The median time to CLAD since LTx was 570 days [150-1770]. Moderate pulmonary artery stenosis (30-50%) was associated with the occurrence of CLAD on CTi (hazard ratio HR = 4.6, CI [1.6-13.2]) and consolidations and pleural effusion on CTf (HR = 2.6, CI [1.3-4.9] and HR = 4.5, CI [1.5-13.6] respectively). The presence of mosaic attenuation (HR = 4.1, CI [1.4-12.5]), consolidations (HR = 2.6, CI [1.3-5.4]), and pleural effusions (p = 0.01, HR = 5.7, CI [1.4-22.3]) were risk factors for BOS on CTf. The consolidations (p = 0.029) and pleural effusions (p = 0.001) were risk factors for death on CTf.

CONCLUSIONS

CTi and CTf in the monitoring of LTx patients could predict CLAD. Moderate pulmonary artery stenosis, mosaic pattern, parenchyma condensations, and pleural effusions were risk factors for CLAD.

CRITICAL RELEVANCE STATEMENT

There is a potential predictive role of chest CT in the follow-up of LTx patients for chronic lung allograft dysfunction (CLAD). Early chest CT should focus on pulmonary artery stenosis (risk factor for CLAD in this study). During the follow-up (at least 9 months post-LTx), parenchymal consolidations and pleural effusions were shown to be risk factors for CLAD, and death in subgroup analyses.

KEY POINTS

• Pulmonary artery stenosis (30-50%) on initial chest-CT following lung transplantation predicts CLAD HR = 4.5; CI [1.6-13.2]. • Pleural effusion and consolidations 1 year after lung transplantation predict CLAD and death. • Early evaluation of lung transplanted patients should evaluate pulmonary artery anastomosis.

The dynamic lung microbiome in health and disease

New methods and technologies within the field of lung biology are beginning to shed new light into the microbial world of the respiratory tract. Long considered to be a sterile environment, it is now clear that the human lungs are frequently exposed to live microbes and their by-products. The nature of the lung microbiome is quite distinct from other microbial communities inhabiting our bodies such as those in the gut. Notably, the microbiome of the lung exhibits a low biomass and is dominated by dynamic fluxes of microbial immigration and clearance, resulting in a bacterial burden and microbiome composition that is fluid in nature rather than fixed. As our understanding of the microbial ecology of the lung improves, it is becoming increasingly apparent that certain disease states can disrupt the microbial-host interface and ultimately affect disease pathogenesis. In this Review, we provide an overview of lower airway microbial dynamics in health and disease and discuss future work that is required to uncover novel therapeutic targets to improve lung health.

Risk of Bronchial Complications After Lung Transplantation With Respiratory Corynebacteria. Results From a Monocenter Retrospective Cohort Study

Corynebacterium spp. are associated with respiratory infections in immunocompromised hosts. A link with bronchial complications after lung transplantation (LTx) has been suggested. We aimed to assess the link between respiratory sampling of Corynebacterium spp. and significant bronchial complication (SBC) after LTx. We performed a single center retrospective study. Inclusion of LTx recipients with at least one respiratory Corynebacterium spp. sample (July 2014 to December 2018). Subjects were matched to unexposed LTx recipients. Primary outcome was SBC occurrence after Corynebacterium spp. isolation. Secondary outcomes were Corynebacterium spp. persistent sampling, chronic lung allograft dysfunction (CLAD) onset and all-cause mortality. Fifty-nine patients with Corynebacterium spp. sampling with 59 without isolation were included. Corynebacterium spp. identification was not associated with SBC occurrence (32.4% vs. 21.6%, p = 0.342). Previous SBC was associated with further isolation of Corynebacterium spp. (OR 3.94, 95% CI [1.72-9.05]). Previous SBC and corticosteroids pulses in the last 3 months were the only factors associated with increased risk of Corynebacterium spp. isolation in multivariate analysis. Corynebacterium spp. sampling was significantly associated with CLAD onset (27.1% vs. 6.9%, p = 0.021). Corynebacterium spp. isolation was not associated with SBC but with higher risk of CLAD. Whether CLAD evolution is affected by Corynebacterium spp. eradication remains to be investigated.

Acute Rejection in the Modern Lung Transplant Era

Acute cellular rejection (ACR) remains a common complication after lung transplantation. Mortality directly related to ACR is low and most patients respond to first-line immunosuppressive treatment. However, a subset of patients may develop refractory or recurrent ACR leading to an accelerated lung function decline and ultimately chronic lung allograft dysfunction. Infectious complications associated with the intensification of immunosuppression can also negatively impact long-term survival. In this review, we summarize the most recent evidence on the mechanisms, risk factors, diagnosis, treatment, and prognosis of ACR. We specifically focus on novel, promising biomarkers which are under investigation for their potential to improve the diagnostic performance of transbronchial biopsies. Finally, for each topic, we highlight current gaps in knowledge and areas for future research.

Chlamydiae from Down Under: The Curious Cases of Chlamydial Infections in Australia

In Australia, the most researched and perhaps the most successful chlamydial species are the human pathogen Chlamydia trachomatis, animal pathogens Chlamydia pecorum and Chlamydia psittaci. C. trachomatis remains the leading cause of sexually transmitted infections in Australians and trachoma in Australian Indigenous populations. C. pecorum is globally recognised as the infamous koala and widespread livestock pathogen, whilst the avian C. psittaci is emerging as a horse pathogen posing zoonotic risks to humans. Certainly not innocuous, the human infections with Chlamydia pneumoniae seem to be less prevalent that other human chlamydial pathogens (namely C. trachomatis). Interestingly, the complete host range for C. pecorum and C. psittaci remains unknown, and infections by other chlamydial organisms in Australian domesticated and wildlife animals are understudied. Considering that chlamydial organisms can be encountered by either host at the human/animal interface, I review the most recent findings of chlamydial organisms infecting Australians, domesticated animals and native wildlife. Furthermore, I also provide commentary from leading Australian Chlamydia experts on challenges and future directions in the Chlamydia research field.

Infections in Heart, Lung, and Heart-Lung Transplantation

Half a century has passed since the first orthotopic heart transplant took place. Surgical innovations allowed for heart, lung, and heart-lung transplantation to save lives of patients with incurable chronic cardiopulmonary conditions. The complexity of the surgical interventions, chronic host health conditions, and antirejection immunosuppressive medications makes infectious complications common. Infections have remained one of the main barriers for successful transplantation and a source of significant morbidity and mortality. Recognition of infections and its management in this setting require outstanding clinical skills since transplant recipients may not exhibit classic signs or symptoms of disease, and laboratory work has some pitfalls. The prevention, identification, and management of infectious diseases complications in this population are a priority to undertake to improve the medical outcomes of transplantation. Herein, we reviewed the historical aspects, epidemiology, and prophylaxis of infections in heart, lung, and heart-lung transplantation. We also discuss the most prevalent organisms affecting the host and the organ systems involved.

Cyclophosphamide for Refractory Acute Cellular Rejection After Lung Transplantation

Background

Acute cellular rejection (ACR) is a major risk factor for chronic lung allograft dysfunction after lung transplantation. Acute cellular rejection can persist or recur despite augmentation of immunosuppression by conventional methods. There are limited therapeutic options in treating these recurrent and refractory ACRs. We describe our experience with cyclophosphamide therapy for recurrent and refractory ACR in lung transplant recipients.

Methods

Six consecutive patients who were treated with cyclophosphamide for recurrent or refractory ACR were included in the series. The primary outcome measures were improvement in ACR score and forced expiratory volume at 1 second. Secondary outcome measures included adverse drug events including bone marrow suppression, gastrointestinal side effects, and infections.

Results

Five of the 6 patients treated demonstrated complete resolution of ACR on follow-up biopsies. Acute cellular rejection score improved after cyclophosphamide treatment (P = 0.03). None of the patients had high grade (≥A3) ACR in the 3 months after cyclophosphamide administration. Cyclophosphamide had no effect on forced expiratory volume at 1 second trend or bronchiolitis obliterans score. All patients tolerated cyclophosphamide with minor gastrointestinal side effects, mild bone marrow suppression, and nonfatal infections that were amenable to treatment.

Conclusions

Cyclophosphamide therapy is an option in treating recurrent and refractory ACR in patients who have failed conventional treatments. Cyclophosphamide is tolerated well without serious adverse drug events (ADE).

Community-Acquired Respiratory Viruses

The incidence of community-acquired respiratory viruses (CARVs) is ∼15 cases per 100 patient-years after lung transplantation (LTx). Paramyxoviruses account for almost 50% of the cases of CARV infection in LTx. Most patients will be symptomatic with a mean decline of 15 to 20% in forced expiratory volume in 1 second. The attributable death rate is low in recent years 15 to 25% CARV infected LTx patients will develop chronic lung allograft dysfunction within a year after CARV infection. This risk seems to be increased in comparison to the noninfected LTx recipient.

Detection rate of CARV dependent on clinical awareness, sampling, and diagnostic method with nucleic acid testing by polymerase chain reaction in bronchoalveolar lavage is the gold standard after LTx.

There is no approved treatment for paramyxoviruses, most centers use ribavirin by various routes. Toxicity of systemic ribavirin is of concern and some patients will have contraindication to this treatment modality. Treatment may reduce the risk to develop chronic lung allograft dysfunction and respiratory failure. Agents under development are inhibiting viral attachment and use silencing mechanisms of viral replication.

Immunosuppressive Treatment and Its Effect on the Occurrence of Pneumocystis jiroveci, Mycoplasma pneumoniae, Chlamydophila pnemoniae, and Legionella pneumophila Infections/Colonizations Among Lung Transplant Recipients

BACKGROUND

The aim of the study was to assess the frequency of infections caused by Pneumocystis jiroveci, Chlamydophila pneumoniae, Legionella pneumophila, and Mycoplasma pneumoniae among lung transplant recipients in the context of immunosuppression.

METHODS

The study group consisted of 94 patients (37 women and 57 men; mean age 42.03 years) transplanted between 2009 and 2016 at the Silesia Center for Heart Diseases (SCCS). Immunosuppressive treatment (induction and maintenance therapy) was assessed. The immunofluorescence methods were used to detect the P. jiroveci, L. pneumophila, C. pneumoniae, and M. pneumoniae antigens in samples obtained from the respiratory tract.

RESULTS

Thirty-two of 94 graft recipients developed atypical or opportunistic infection. The median time of its occurrence was 178 days after transplantation. P. jiroveci was responsible for 84.38% of first infections. Five patients developed infection with P. jiroveci and C. pneumoniae. None of the infections occurred during induction of immunosuppression. An opportunistic or atypical infection developed in 19.35% of the patients treated with a tacrolimus-based regimen, and in 43.33% of patients on a cyclosporine-based regimen.

CONCLUSION

Infection with P. jiroveci is a recognized problem after lung transplantation and should be monitored. The percentage of infected patients is higher in patients treated with a cyclosporine-based regimen in comparison to those treated with tacrolimus.

Inhibitors of Apoptosis Protein Antagonists (Smac Mimetic Compounds) Control Polarization of Macrophages during Microbial Challenge and Sterile Inflammatory Responses

Apoptosis is a physiological cell death process essential for development, tissue homeostasis, and for immune defense of multicellular animals. Inhibitors of apoptosis proteins (IAPs) regulate apoptosis in response to various cellular assaults. Using both genetic and pharmacological approaches we demonstrate here that the IAPs not only support opportunistic survival of intracellular human pathogens like Chlamydia pneumoniae but also control plasticity of iNOS+ M1 macrophage during the course of infection and render them refractory for immune stimulation. Treatment of Th1 primed macrophages with birinapant (IAP-specific antagonist) inhibited NO generation and relevant proteins involved in innate immune signaling. Accordingly, birinapant promoted hypoxia, angiogenesis, and tumor-induced M2 polarization of iNOS+ M1 macrophages. Interestingly, birinapant-driven changes in immune signaling were accompanied with changes in the expression of various proteins involved in the metabolism, and thus revealing the new role of IAPs in immune metabolic reprogramming in committed macrophages. Taken together, our study reveals the significance of IAP targeting approaches (Smac mimetic compounds) for the management of infectious and inflammatory diseases relying on macrophage plasticity.

Pathology of Lung Rejection: Cellular and Humoral Mediated

Acute rejection is an important risk factor for bronchiolitis obliterans syndrome, the clinical manifestation of chronic airway rejection in lung allograft recipients. Patients with acute rejection might be asymptomatic or present with symptoms that are not specific and can be also seen in other conditions. Clinical tests such as pulmonary function tests and imaging studies among others usually are abnormal; however, their results are also not specific for acute rejection. Histopathologic features of acute rejection in adequate samples of transbronchial lung biopsy of the lung allograft are currently the gold standard to assess for acute rejection in lung transplant recipients. Acute alloreactive injury can affect both the vasculature and the airways. Currently, the guidelines of the 2007 International Society of Heart and Lung Transplantation consensus conference are recommended for the histopathologic assessment of rejection. There are no specific morphologic features recognized to diagnose antibody-mediated rejection (AMR) in lung allografts. Therefore, the diagnosis of AMR currently requires a “triple test” including clinical features, serologic evidence of donor-specific antibodies, and pathologic findings supportive of AMR. Complement 4d deposition is used to support a diagnosis of AMR in many solid organ transplants; however, its significance for the diagnosis of AMR in lung allografts is not entirely clear. This chapter discusses the currently recommended guidelines for the assessment of cellular rejection of lung allografts and summarizes our knowledge about morphologic features and immunophenotypic tests that might help in the diagnosis of AMR.

Lower Respiratory Tract Infections

This review will focus on the infectious etiologies and more common noninfectious causes of lower respiratory tract syndromes among major immunosuppressed populations. The changing epidemiology of infections in the era of highly active antiretroviral therapy (HAART) in the case of HIV-positive patients and the impacts of both newer immune-suppressant therapies and anti-infective prophylaxis for other immunocompromised hosts will be discussed, with emphasis on diagnostic approaches and practice algorithms.

The Impact of Infection on Chronic Allograft Dysfunction and Allograft Survival After Solid Organ Transplantation

Infectious diseases after solid organ transplantation (SOT) are a significant cause of morbidity and reduced allograft and patient survival; however, the influence of infection on the development of chronic allograft dysfunction has not been completely delineated. Some viral infections appear to affect allograft function by both inducing direct tissue damage and immunologically related injury, including acute rejection. In particular, this has been observed for cytomegalovirus (CMV) infection in all SOT recipients and for BK virus infection in kidney transplant recipients, for community-acquired respiratory viruses in lung transplant recipients, and for hepatitis C virus in liver transplant recipients. The impact of bacterial and fungal infections is less clear, but bacterial urinary tract infections and respiratory tract colonization by Pseudomonas aeruginosa and Aspergillus spp appear to be correlated with higher rates of chronic allograft dysfunction in kidney and lung transplant recipients, respectively. Evidence supports the beneficial effects of the use of antiviral prophylaxis for CMV in improving allograft function and survival in SOT recipients. Nevertheless, there is still a need for prospective interventional trials assessing the potential effects of preventive and therapeutic strategies against bacterial and fungal infection for reducing or delaying the development of chronic allograft dysfunction.

A new classification system for chronic lung allograft dysfunction

Although survival after lung transplantation has improved significantly during the last decade, chronic rejection is thought to be the major cause of late mortality. The physiologic hallmark of chronic rejection has been a persistent fall in forced expiratory volume in 1 second associated with an obstructive ventilatory defect, for which the term bronchiolitis obliterans syndrome (BOS) was defined to allow a uniformity of description and grading of severity throughout the world. Although BOS was generally thought to be irreversible, recent evidence suggests that some patients with BOS may respond to azithromycin with > 10% improvement in their forced expiratory volume in 1 second. In addition, a restrictive form of chronic rejection has recently been described that does not fit the strict definition of BOS as an obstructive defect. Hence, the term chronic lung allograft dysfunction (CLAD) has been introduced to cover all forms of graft dysfunction, but CLAD has yet to be defined. We propose a definition of CLAD and a flow chart that may facilitate recognition of the different phenotypes of CLAD that can complicate the clinical course of lung transplant recipients.

Bronchiolitis obliterans syndrome and restrictive allograft syndrome: do risk factors differ?

BACKGROUND

Chronic rejection is the major problem hampering long-term survival after lung transplantation. Recently, it became clear that patients may develop an obstructive (bronchiolitis obliterans syndrome [BOS]) or a restrictive lung function defect (restrictive allograft syndrome [RAS]), for which specific risk factors are unknown.

METHODS

A retrospective analysis of our lung transplantation cohort was performed (n=380). Patients with an irreversible decline in forced expiratory volume in 1 second were identified and classified as BOS or RAS. Patient characteristics, bronchoalveolar lavage (BAL) cellularity, rates of respiratory tract infection, colonization, acute rejection, and lymphocytic bronchiolitis were compared between BOS, RAS, and stable patients.

RESULTS

There were 103 patients suffering from chronic rejection, of which 79 had BOS and 24 were diagnosed with RAS. There were more patients with infection and pseudomonal colonizations in BOS and RAS compared with control (P=0.0090 and P=0.0034, respectively). More patients ever experienced acute and severe acute rejections (A≥2; both P<0.0001) and lymphocytic bronchiolitis (P=0.0006) in BOS and RAS versus control. There were more patients experiencing severe lymphocytic bronchiolitis in RAS compared with BOS (P=0.031). BAL neutrophilia in BOS and RAS were elevated at days 360, 540, and 720 versus control. BOS, but especially RAS patients, experienced more frequent episodes of increased BAL eosinophilia (≥2%; P<0.0001).

CONCLUSION

Acute rejection, lymphocytic bronchiolitis, colonization with pseudomonas, infection, and BAL eosinophilia and neutrophilia are risk factors for the later development not only of RAS but also of BOS.

Lung transplant infection

Lung transplantation has become an accepted therapeutic procedure for the treatment of end‐stage pulmonary parenchymal and vascular disease. Despite improved survival rates over the decades, lung transplant recipients have lower survival rates than other solid organ transplant recipients. The morbidity and mortality following lung transplantation is largely due to infection‐ and rejection‐related complications. This article will review the common infections that develop in the lung transplant recipient, including the general risk factors for infection in this population, and the most frequent bacterial, viral, fungal and other less frequent opportunistic infections. The epidemiology, diagnosis, prophylaxis, treatment and outcomes for the different microbial pathogens will be reviewed. The effects of infection on lung transplant rejection will also be discussed.

Role of long term antibiotics in chronic respiratory diseases

Antibiotics are commonly used in the management of respiratory disorders such as cystic fibrosis (CF), non-CF bronchiectasis, asthma and COPD. In those conditions long-term antibiotics can be delivered as nebulised aerosols or administered orally. In CF, nebulised colomycin or tobramycin improve lung function, reduce number of exacerbations and improve quality of life (QoL). Oral antibiotics, such as macrolides, have acquired wide use not only as anti-microbial agents but also due to their anti-inflammatory and pro-kinetic properties. In CF, macrolides such as azithromycin have been shown to improve the lung function and reduce frequency of infective exacerbations. Similarly macrolides have been shown to have some benefits in COPD including reduction in a number of exacerbations. In asthma, macrolides have been reported to improve some subjective parameters, bronchial hyperresponsiveness and airway inflammation; however have no benefits on lung function or overall asthma control. Macrolides have also been used with beneficial effects in less common disorders such as diffuse panbronchiolitis or post-transplant bronchiolitis obliterans syndrome. In this review we describe our current knowledge the use of long-term antibiotics in conditions such as CF, non-CF bronchiectasis, asthma and COPD together with up-to-date clinical and scientific evidence to support our understanding of the use of antibiotics in those conditions.

Reestablishment of recipient-associated microbiota in the lung allograft is linked to reduced risk of bronchiolitis obliterans syndrome

RATIONALE

Bronchiolitis obliterans syndrome (BOS) is the primary limiting factor for long-term survival after lung transplantation, and has previously been associated with microbial infections.

OBJECTIVES

To cross-sectionally and longitudinally characterize microbial communities in allografts from transplant recipients with and without BOS using a culture-independent method based on high-throughput sequencing.

METHODS

Allografts were sampled by bronchoalveolar lavage, and microbial communities were profiled using 16S rRNA gene amplicon pyrosequencing. Community profiles were compared using the weighted Unifrac metric and the relationship between microbial populations, BOS, and other covariates was explored using PERMANOVA and logistic regression.

MEASUREMENTS AND MAIN RESULTS

Microbial communities in transplant patients fell into two main groups: those dominated by Pseudomonas or those dominated by Streptococcus and Veillonella, which seem to be mutually exclusive lung microbiomes. Aspergillus culture was also negatively correlated with the Pseudomonas-dominated group. The reestablishment of dominant populations present in patients pretransplant, notably Pseudomonas in individuals with cystic fibrosis, was negatively correlated with BOS.

CONCLUSIONS

Recolonization of the allograft by Pseudomonas in individuals with cystic fibrosis is not associated with BOS. In general, reestablishment of pretransplant lung populations in the allograft seems to have a protective effect against BOS, whereas de novo acquisition of microbial populations often belonging to the same genera may increase the risk of BOS.

The Role of Infections in BOS

Background: Infectious agents, particularly cytomegalovirus (CMV), have long been considered to be potential triggers for BOS, although the exact magnitude of the role of infections and the mechanisms thereof remain an area of active research. Methods: This chapter will review previous literature and newer results concerning the possible roles of CMV, other herpesviruses, community-acquired respiratory viruses, bacteria (including Pseudomonas, other gram-negative, gram-positive, and atypical organisms), and fungi, including colonization as well as invasive infection. Results: The text reviews and evaluates the body of literature supporting a role for these infectious agents as risk factors for BOS and time to BOS. Changing patterns of infection over time are taken into account, and studies that have shown an association between BOS (or lack thereof) and CMV are reviewed. Strategies for prevention or early treatment of infections are discussed as potential means of preserving allograft function long term. Immunizations, stringent infection-control practices, and antimicrobial treatment including newer therapies will be discussed. Conclusion: In addition to the classic literature that has focused on CMV, an expanding spectrum of infectious organisms has been implicated as possible risk factors for BOS. Increasing knowledge of the impact of long-term antiviral suppression, prophylaxis, and outcomes of early therapy will help guide future recipient management.

Managing complications following lung transplantation

Lung transplantation has become a proven therapeutic option for patients with end-stage lung disease, extending life and providing improved quality of life to those who otherwise would continue to be breathless and oxygen-dependent. Over the past 20 years, considerable experience has been gained in understanding the multitude of medical and surgical issues that impact upon patient survival. Today, clinicians have an armamentarium of tools to manage diverse problems such as primary graft dysfunction, acute and chronic allograft rejection, airway anastomotic issues, infectious complications, renal dysfunction, diabetes and osteoporosis, hematological and gastrointestinal problems, malignancy, and other unique issues that confront immunosuppressed solid organ transplant recipients.

Non-tuberculous mycobacterium infection after lung transplantation is associated with increased mortality

BACKGROUND

Pulmonary non-tuberculous mycobacterial (NTM) infection is relatively common after lung transplantation, but the effect on mortality remains undetermined. Herein we describe our experience with pulmonary NTM infection after lung transplantation and hypothesized that non-tuberculous mycobacterial infection after lung transplantation would be associated with increased mortality.

METHODS

We retrospectively evaluated 201 primary lung transplant recipients transplanted between January 2000 and August 2006. Serial bronchoscopies with bronchoalveolar lavage and transbronchial biopsy were performed according to a surveillance protocol and when clinically indicated. The diagnosis NTM infection was established by a positive NTM culture in a bronchoalveolar lavage sample or in at least two separate expectorated sputum samples. NTM infections were further classified as "disease" or "colonization," based on whether or not NTM infection patients developed symptoms and characteristic radiographic findings.

RESULTS

Thirty-six (18%) recipients were diagnosed with pulmonary NTM infection at a median of 97 days post-transplantation: 9 were classified as NTM disease and the remaining 27 as NTM colonization cases. Single lung transplant was a significant risk factor for NTM infection (HR 2.25, p = 0.02). NTM colonization was a risk factor for NTM disease (HR 8.39, p = 0.003). NTM infection significantly increased the risk of death after lung transplantation (HR 2.61, p = 0.001) and persisted in multivariate models controlling for single lung transplant and bronchiolitis obliterans syndrome. The increased risk was seen for both NTM colonization and NTM disease. Among the patients who died, non-NTM infection was a more common contributing factor in the cause of death for the NTM infection group (44% vs 12%, p = 0.04).

CONCLUSIONS

Non-tuberculous mycobacterial infection is common after lung transplantation. NTM colonization and treated acute rejection are risk factors for NTM disease. NTM infection is associated with increased risk of mortality independent of bronchiolitis obliterans syndrome.

Bacterial infections, alloimmunity, and transplantation tolerance

Transplantation of solid organs across histocompatibility barriers in the absence of immunosuppression is invariably followed by acute allograft rejection. Although several immunosuppressive regimens have been developed to prevent allograft rejection, these global immunosuppressive agents effectively inhibit all T cells, leaving the host vulnerable to infections. Thus, a major goal in transplantation immunology is to induce donor-specific tolerance that results in the extended suppression of allograft-specific immune responses, while leaving the remainder of the immune system competent to fight infections and malignancies. Initial successes in identifying approaches that successfully induce transplantation tolerance in experimental models have led to a newer research focus of identifying potential barriers to the induction of such tolerance as well as events that may reverse established allograft tolerance. Both clinical and experimental studies have identified bacterial infections as a possible trigger of allograft rejection. Recently, experimental models of transplantation tolerance have identified that bacterial signals can promote acute allograft rejection either by preventing the induction of transplantation tolerance or by reversing tolerance after it has been stably established. This review summarizes experimental and clinical literature supporting the hypothesis that bacterial infections and innate immunity can qualitatively and quantitatively alter adaptive alloreactivity through effects on innate immune responses.

Aspergillus colonization of the lung allograft is a risk factor for bronchiolitis obliterans syndrome

Multiple infections have been linked with the development of bronchiolitis obliterans syndrome (BOS) post-lung transplantation. Lung allograft airway colonization by Aspergillus species is common among lung transplant recipients. We hypothesized that Aspergillus colonization may promote the development of BOS and may decrease survival post-lung transplantation. We reviewed all lung transplant recipients transplanted in our center between January 2000 and June 2006. Bronchoscopy was performed according to a surveillance protocol and when clinically indicated. Aspergillus colonization was defined as a positive culture from bronchoalveolar lavage or two sputum cultures positive for the same Aspergillus species, in the absence of invasive pulmonary Aspergillosis. We found that Aspergillus colonization was strongly associated with BOS and BOS related mortality in Cox regression analyses. Aspergillus colonization typically preceded the development of BOS by a median of 261 days (95% CI 87-520). Furthermore, in a multivariate Cox regression model, Aspergillus colonization was a distinct risk factor for BOS, independent of acute rejection. These data suggest a potential causative role for Aspergillus colonization in the development of BOS post-lung transplantation and raise the possibility that strategies aimed to prevent Aspergillus colonization may help delay or reduce the incidence of BOS.

Community-acquired respiratory viral infections in lung transplant recipients: a single season cohort study

BACKGROUND

The impact of community-acquired respiratory virus (CARV) infections on bronchiolitis obliterans syndrome (BOS) and outcome after lung transplantation (LTx) and diagnostic techniques were prospectively evaluated.

METHODS

A single-center prospective cohort study was performed in LTx-outpatients between October 31, 2005 and April 30, 2006. Symptoms of respiratory tract infections were recorded and nasopharyngeal and oropharyngeal swabs were obtained. Lower respiratory sampling was performed when indicated. Immunofluorescence testing, cultures, and polymerase chain reaction for 12 different CARV were applied. Patients were followed up until December 31, 2007. New onset and BOS-stage was recorded 1 year after presentation.

RESULTS

Three hundred eighty-eight LTx-recipients were screened. Fifty-one percent reported of symptoms of respiratory tract infection. Seven hundred seventy upper and 180 lower respiratory samples were obtained. Thirty-four CARV were detected in 30 patients (7.7%): 12 parainfluenza, 7 respiratory syncytial virus, 6 metapneumovirus, 5 coronavirus, 3 rhinovirus, and 1 influenza virus. At 1 year, 43 new cases of BOS developed. One-year incidence of BOS was 25.0% in CARV-positive versus 9.0% in CARV-negative patients (log-rank P=0.01). Symptomatic CARV-infection proved to be a significant covariate for 1-year BOS-free survival in multivariate analysis (P=0.002, adjusted hazard ratio 4.13). CARV-infection did not influence BOS progression in 88 patients with prior BOS (P 0.45). After paramyxovirus infection, 8 of 24 patients developed new-onset BOS, whereas no case was recorded after rhinovirus and coronavirus infection.

DISCUSSION

Surveillance detected CARV in LTx outpatients infrequently. Symptomatic CARV-infection increases the risk for new onset of BOS, but not progression. Risk to develop BOS was especially increased after paramyxovirus infection.

Acute rejection and humoral sensitization in lung transplant recipients

Despite the recent introduction of many improved immunosuppressive agents for use in transplantation, acute rejection affects up to 55% of lung transplant recipients within the first year after transplant. Acute lung allograft rejection is defined as perivascular or peribronchiolar mononuclear inflammation. Although histopathologic signs of rejection often resolve with treatment, the frequency and severity of acute rejections represent the most important risk factor for the subsequent development of bronchiolitis obliterans syndrome (BOS), a condition of progressive airflow obstruction that limits survival to only 50% at 5 years after lung transplantation. Recent evidence demonstrates that peribronchiolar mononuclear inflammation (also known as lymphocytic bronchiolitis) or even a single episode of minimal perivascular inflammation significantly increase the risk for BOS. We comprehensively review the clinical presentation, diagnosis, histopathologic features, and mechanisms of acute cellular lung rejection. In addition, we consider emerging evidence that humoral rejection occurs in lung transplantation, characterized by local complement activation or the presence of antibody to donor human leukocyte antigens (HLA). We discuss in detail methods for HLA antibody detection as well as the clinical relevance, the mechanisms, and the pathologic hallmarks of humoral injury. Treatment options for cellular rejection include high-dose methylprednisolone, antithymocyte globulin, or alemtuzumab. Treatment options for humoral rejection include intravenous immunoglobulin, plasmapheresis, or rituximab. A greater mechanistic understanding of cellular and humoral forms of rejection and their role in the pathogenesis of BOS is critical in developing therapies that extend long-term survival after lung transplantation.

Lung

Experiments with animals in the 1940 and 1950s demonstrated that lung transplantation was technically possible [33]. In 1963, Dr. James Hardy performed the first human lung transplantation. The recipient survived 18 days, ultimately succumbing to renal failure and malnutrition [58]. From 1963 through 1978, multiple attempts at lung transplantation failed because of rejection and complications at the bronchial anastomosis. In the 1980s, improvements in immunosuppression, especially the introduction of cyclosporin A, and enhanced surgical techniques led to renewed interest in organ transplantation. In 1981, a 45-year-old-woman received the first successful heart–lung transplantation for idiopathic pulmonary arterial hypertension (IPAH) [106]. She survived 5 years after the procedure. Two years later the first successful single lung transplantation for idiopathic pulmonary fibrosis (IPF) [128] was reported, and in 1986 the first double lung transplantation for emphysema [25] was performed.

Interstitial inflammatory lesions of the pulmonary allograft: a retrospective analysis of 2697 transbronchial biopsies

BACKGROUND

Parenchymal and bronchial inflammatory and fibrotic lesions other than acute cellular rejection (ACR) and lymphocytic bronchiolitis are prevalent; however, the context in which they appear is unknown, and often no specific treatment is instigated.

OBJECTIVES

To describe the prevalence, incidence and possible associations between commonly identified inflammatory and fibrotic lesions in the pulmonary allograft.

METHODS

Retrospective chart review of all transbronchial biopsies performed within the first 2 years of 299 lung-transplanted patients in the period 1996 to 2006.

RESULTS

A total of 2697 biopsies were evaluated corresponding to a mean of 6+/-2 (median 8) completed schedules per patient. Diffuse alveolar damage (DAD) was the second most common histological finding within the first 2 weeks after transplantation. The peak prevalence of bronchiolitis obliterans organizing pneumonia (BOOP) and interstitial pneumonitis occurred at 4 to 6 weeks, and 6 to 12 weeks, respectively. There was a steady increase in the cumulative proportion of patients with fibrosis and bronchiolitis obliterans, at each successive scheduled surveillance time point beyond 3 months posttransplantation. The strongest histological correlations were between ACR and lymphocytic bronchiolitis (OR 5.1, P<0.0001) or interstitial fibrosis (OR 3.2, P<0.0001). Patients with interstitial pneumonitis and pulmonary hemosiderosis were also more likely to demonstrate the finding of interstitial fibrosis (OR 3.0 and 3.7, P<0.0001, respectively). Acute cellular rejection was not associated with DAD, and patients with lymphocytic bronchiolitis were not more likely to demonstrate features of organizing pneumonia (DAD or BOOP).

CONCLUSIONS

Histologic findings of ACR, lymphocytic bronchiolitis, BOOP, and interstitial pneumonitis were directly associated with the development of interstitial fibrosis and bronchiolitis obliterans.

Atypical pneumonias: current clinical concepts focusing on Legionnaires' disease

PURPOSE OF REVIEW

This review provides clinicians with an overview of the clinical features of the atypical pneumonias. Atypical community-acquired pneumonia pathogens cause systemic infections with pneumonia. The key to the clinical diagnosis of atypical pneumonias depends on recognizing the characteristic pattern of extrapulmonary organ involvement different for each pathogen. As Legionella is likely to present as severe pneumonia and does not respond to beta-lactams, it is important to presumptively diagnose Legionnaires' disease clinically so that Legionella coverage is included in empiric therapy. This study reviews the clinical features and nonspecific laboratory markers of atypical pathogens, focusing on Legionnaires' disease.

RECENT FINDINGS

Case reports/outbreaks increase our understanding of Legionnaires' disease transmission. Both Mycoplasma pneumoniae and Chlamydophilia pneumoniae may cause asthma. Antimicrobial therapy of Chlamydophilia pneumoniae/Mycoplasma pneumoniae is important to decrease person-to-person spread and to decrease potential long-term sequelae.

SUMMARY

Atypical pulmonary pathogens cause systemic infections accompanied by a variety of characteristic extrapulmonary features. Clinically, it is possible to differentiate Legionnaires' disease from the other typical/atypical pneumonias. Rapid clinical diagnosis of atypical pathogens, particularly Legionnaires' disease, is important in selecting effective empiric therapy and prompting definitive laboratory testing.

Severity of lymphocytic bronchiolitis predicts long-term outcome after lung transplantation

RATIONALE

Severe and recurrent acute vascular rejection of the pulmonary allograft is an accepted major risk factor for obliterative bronchiolitis.

OBJECTIVES

We assessed the role of lymphocytic bronchiolitis as a risk factor for bronchiolitis obliterans syndrome (BOS) and death after lung transplantation.

METHODS

Retrospective analysis of 341 90-day survivors of lung transplant performed in 1995-2005 who underwent 1,770 transbronchial lung biopsy procedures.

MEASUREMENTS AND MAIN RESULTS

Transbronchial biopsies showed grade B0 (normal) (n = 501), B1 (minimal) (n = 762), B2 (mild) (n = 176), B3 (moderate) (n = 70), B4 (severe) (n = 4) lymphocytic bronchiolitis, and Bx (no bronchiolar tissue) (n = 75). A total of 182 transbronchial biopsies were ungraded (8 inadequate, 142 cytomegalovirus, 32 other diagnoses). Lung transplant recipients were grouped by highest B grade before diagnosis of BOS: B0 (n = 12), B1 (n = 166), B2 (n = 89), and B3-B4 (n = 51). Twenty-three were unclassifiable. Cumulative incidence of BOS and death were dependent on highest B grade (Kaplan-Meier, P < 0.001, log-rank). Multivariable Cox proportional hazards analysis showed significant risks for BOS were highest B grade (relative risk [RR], 1.62; 95% confidence interval [CI], 1.31-2.00) (P < 0.001), longer ischemic time (RR, 1.00; CI, 1.00-1.00) (P < 0.05), and recent year of transplant (RR, 0.93; CI, 0.87-1.00) (P < 0.05), whereas risks for death were BOS as a time-dependent covariable (RR, 19.10; CI, 11.07-32.96) (P < 0.001) and highest B grade (RR, 1.36; CI, 1.07-1.72) (P < 0.05). Acute vascular rejection was not a significant risk factor in either model.

CONCLUSIONS

Severity of lymphocytic bronchiolitis is associated with increased risk of BOS and death after lung transplantation independent of acute vascular rejection.

Pulmonary infections after lung transplantation

A tüdőtranszplantáció napjainkban már rutinszerűen végzett beavatkozássá vált a végstádiumú parenchymás és vascularis tüdőbetegségekben. Az elmúlt két évtized során több mint 20 ezer tüdőtranszplantációt végeztek a világon. Az immunszuppresszív szerek fejlődésének eredményeként az életet veszélyeztető akut rejekciók száma jelentősen csökkent, az első éven belüli halálozás csupán 2%-át okozza. A legnagyobb arányban az infekciók felelősek a korai és a késői morbiditásért és mortalitásért. A posztoperatív első 30 napon belüli halálozás 21,2%-a, az első éven belüli halálozás 40%-a infekciós eredetű. Az első hónapban a betegek 35–70%-ánál bakteriális pneumónia alakul ki, amelynek kb. felét Gram-negatív pálcák okozzák, dominálóan Pseudomonas-törzsek. A betegek a műtétet követően antibiotikus profilaxisban részesülnek, amit aztán a donortüdőből kimutatott törzs rezisztenciatesztje alapján módosíthatunk. A korai posztoperatív időszakban az invazív gomba- (Aspergillus-, Candida-) és CMV-infekciók a 100 napig tartó inhalatív amphotericin és szisztémás valganciklovir-profilaxis hatására kevesebb mint 10–10%-ban lépnek fel. Számuk a profilaxis befejezte után emelkedik. A későbbiekben kialakuló bronchiolitis obliterans szindróma (BOS) szintén hajlamosít a fertőzésekre. Ennek jelentőségét az adja, hogy 5 évvel a műtét után a betegek kb. 50%-ánál detektálható a BOS. Az infekciók sikeres leküzdésének alapja a rutinszerűen, illetve a tünetek fellépte után minél hamarabb elvégzett kontroll (laboratóriumi, radiológiai, légzésfunkciós, köpet- és bronchoszkópos vizsgálatok), majd a célzott terápia bevezetése. A munka célja a tüdőtranszplantáltaknál jelentkező leggyakoribb infekciók klinikai manifesztációjának, diagnosztikájának és kezelésének áttekintése.

Pulmonary infections in transplantation pathology

CONTEXT

Pulmonary infections are common and often life-threatening in solid organ and stem cell transplant recipients. Understanding their pathology is critical to making improvements in care and survival as well as in surgical techniques, immunosuppression management, prophylaxis, and treatment. Pulmonary infections are particularly common and serious in the susceptible population of lung transplant recipients.

OBJECTIVE

To summarize recent updates in the field for opportunistic infections and some common pathogens, and to consider the role of the diagnostic pulmonary histopathologist as well as advances in molecular diagnosis.

DATA SOURCES

This work is based on a selected review of the relevant medical and scientific literature, with emphasis on lung transplantation experience gained during 2 decades of practice.

CONCLUSIONS

Pulmonary infections in transplant recipients present a diagnostic challenge and are a continuing source of mortality and morbidity despite improvement in prophylaxis and treatment. Accurate diagnosis requires multidisciplinary input from clinicians, radiologists, and pathology disciplines as well as complementary molecular methods.

Challenges in pulmonary fibrosis. 2: Bronchiolocentric fibrosis

Bronchiolocentric fibrosis is essentially represented by the pathological pattern of constrictive fibrotic bronchiolitis obliterans. The corresponding clinical condition (obliterative bronchiolitis) is characterised by dyspnoea, airflow obstruction at lung function testing and air trapping with characteristic mosaic features on expiratory high resolution CT scans. Bronchiolitis obliterans may result from many causes including acute diffuse bronchiolar damage after inhalation of toxic gases or fumes, alloimmune chronic processes after lung or haematopoietic stem cell transplantation, or connective tissue disease (especially rheumatoid arthritis). Airway-centred interstitial fibrosis and bronchiolar metaplasia are other features of bronchiolocentric fibrosis.

Simkania negevensis in bronchoalveolar lavage of lung transplant recipients: a possible association with acute rejection

BACKGROUND

Simkania negevensis is a novel organism closely related to chlamydiae. The organism has been associated with community acquired pneumonia and acute exacerbation of chronic obstructive pulmonary disease. The prevalence and pathogenic potential of S. negevensis is not known in lung transplant recipients.

METHODS

In this multicenter study comparative analysis of bronchoalveolar lavage (BAL) in lung transplants (Tx) and kidney Tx, immunocompromised and nasopharyngeal (NP) washes of immunocompetent patients was done. The BAL specimens were tested by nested polymerase chain reaction (PCR) for C. pneumoniae and S. negevensis. Selected S. negevensis positive PCR cases were confirmed by culture.

RESULTS

In the initial 41 BAL samples S. negevensis was detected in 97.5% (40/41) of lung transplant recipients as compared to 14.1% (1/7) in other organ transplant recipients (P<0.0001). In the sequential samples of 19 lung transplant recipients, 59% (24/41) had concomitant positive PCR and rejection as compared to 30% (3/10) who had negative PCR but had rejection (P=0.16). S. negevensis infection had hazard ratio of 3.29 (95% CI: 0.73-14.76; P=0.11) for developing acute rejection.

CONCLUSION

S. negevensis is highly prevalent in liver Tx recipients and may be associated with acute rejection.

Cyclosporine C2 Target Levels and Acute Cellular Rejection After Lung Transplantation

BACKGROUND

Acute pulmonary allograft rejection (AR) is the most important risk factor for bronchiolitis obliterans syndrome (BOS), which is associated with reduced quality of life and decreased survival after lung transplantation (LTx). Trough (C0) cyclosporine (CyA) levels have a poor correlation with area-under-the-curve (AUC) measurements of cyclosporine exposure compared with 2-hour post-dose (C2) levels, but there are no published guidelines for C2 levels after LTx. Hence, we assessed the utility of C2 target levels to prevent AR.

METHODS

Fifty consecutive de novo LTx patients (bilateral, 44; single, 3; heart-lung, 3; cystic fibrosis, 20; non-cystic fibrosis, 30) managed with CyA were assigned target C2 levels as follows: >800 microg/liter within 48 hours; >1,200 microg/liter from Week 1 to Month 1; >1,000 microg/liter in Month 2; >800 microg/liter in Month 3; >700 in microg/liter in Months 3 to 6; and >600 microg/liter thereafter. Surveillance transbronchial biopsies (TBBxs) were performed at 3, 6, 9 and 12 weeks. An intention-to-treat analysis was performed and results compared with our historic controls managed by C0 monitoring.

RESULTS

Fifteen of 50 (30%) LTx recipients developed AR on 23 of 171 TBBxs (Grade A2:A3 = 21:2) during follow-up (mean +/- SD) of 1,185 +/- 426 days (range, 16 to 1,790 days). Eighteen of 23 AR episodes occurred after sub-target C2 levels. The 30-day, 1-, 3- and 5-year actuarial survival rates were 98%, 94%, 82% and 77%, respectively. Thirteen of 48 (27%) evaluable LTx recipients developed BOS with 1-, 3- and 5-year freedom-from-BOS rates of 96%, 79% and 59%, respectively. Only 1 patient developed severe renal dysfunction.

CONCLUSIONS

Achieving and maintaining target C2 levels after LTx is associated with reduced rates of AR and BOS, preservation of renal function, and excellent short-term survival rates when compared with historic controls.

Macrolide antibiotics and bronchiolitis obliterans following lung transplantation

The anti-inflammatory effects of macrolide antibiotics are of emerging importance. Over the past 20 years, chronic inflammatory respiratory conditions, including diffuse panbronchiolitis, cystic fibrosis and asthma have benefited from long-term low-dose macrolide therapy. Obliterative bronchiolitis, a form of chronic allograft dysfunction in lung transplant recipients, has been reported to be a condition in which macrolide therapy may be indicated. A number of recent cohort studies have been encouraging. Disease progression was delayed with macrolide antibiotic therapy as patients showed a sustained improvement in pulmonary function tests. Up to now, obliterative bronchiolitis has been resistant to most forms of proposed treatment. This review aims to highlight the etiology of obliterative bronchiolitis, the mechanisms of immunomodulation associated with macrolide therapy and how macrolide therapy may be effective by way of these possible mechanisms.

Azithromycin reduces airway neutrophilia and interleukin-8 in patients with bronchiolitis obliterans syndrome

RATIONALE

Bronchiolitis obliterans syndrome (BOS) remains the leading cause of death after lung transplantation. Treatment is difficult, although azithromycin has recently been shown to improve FEV(1). The exact mechanism of action is unclear.

HYPOTHESES

(1) Azithromycin reduces airway neutrophilia and interleukin (IL)-8 and (2) airway neutrophilia predicts the improvement in FEV(1).

METHODS

Fourteen lung transplant patients with BOS (between BOS 0-p and BOS 3) were treated with azithromycin, in addition to their current immunosuppressive treatment. Before and 3 mo after azithromycin was introduced, bronchoscopy with bronchoalveolar lavage (BAL) was performed for cell differentiation and to measure IL-8 and IL-17 mRNA ratios.

RESULTS

The FEV(1) increased from 2.36 (+/- 0.82 L) to 2.67 L (+/- 0.85 L; p = 0.007), whereas the percentage of BAL neutrophilia decreased from 35.1 (+/- 35.7%) to 5.7% (+/- 6.5%; p = 0.0024). There were six responders to azithromycin (with an FEV(1) increase of > 10%) and eight nonresponders. Using categorical univariate linear regression analysis, the main significant differences in characteristics between responders and nonresponders were the initial BAL neutrophilia (p < 0.0001), IL-8 mRNA ratio (p = 0.0009), and the postoperative day at which azithromycin was started (p = 0.036). There was a significant correlation between the initial percentage of BAL neutrophilia and the changes in FEV(1) after 3 mo (r = 0.79, p = 0.0019).

CONCLUSION

Azithromycin significantly reduces airway neutrophilia and IL-8 mRNA in patients with BOS. Responders have a significantly higher BAL neutrophilia and IL-8 compared with nonresponders and had commenced treatment earlier after transplantation. BAL neutrophilia can be used as a predictor for the FEV(1) response to azithromycin.

Transplant-related immunosuppression: a review of immunosuppression and pulmonary infections

Solid organ and hematopoietic stem cell transplantation are definitive therapies for a variety of end-stage diseases. Immunosuppression has improved graft survival but leaves the patient susceptible to infectious complications. Of these, pulmonary infections are the leading cause of morbidity and mortality in the transplant recipient. Allograft rejection is mediated primarily by T cells, with B cells playing a role via antibody production. Depending on the transplant type, rejection can be hyperacute, acute, or chronic. Hyperacute rejection occurs as an immediate response to preformed antibodies to donor human leukocyte antigens. Acute cellular rejection involves recipient T-cell recognition of human leukocyte antigen molecules expressed on donor-derived, antigen-presenting cells (direct allorecognition) or presentation of donor-derived peptides by recipient antigen-presenting cells to recipient T cells (indirect allorecognition). Once the alloantigens are recognized as foreign, the activation, proliferation, and production of cytokines by T lymphocytes and other immune cells lead to the amplification of the alloimmune response. This complex process involves the generation of effector T cells, antibody production by activated B cells, and macrophage activation. Alloimmunity is facilitated by the production of many cytokines, chemokines, and other effector molecules, such as complement. The immunosuppressants involve many classes of drugs, including antibody therapies that eliminate specific groups of cells or alter signaling pathways used by effector cells. The article reviews the agents and associated infections.