Diagnostic value of follow-up transbronchial lung biopsy after lung rejection

Interventional pulmonology techniques in lung transplantation

Lung transplantation is a key therapeutic option for several end-stage lung diseases. Interventional pulmonology techniques, mostly bronchoscopy, play a key role throughout the whole path of lung transplantation, from donor evaluation to diagnosis and management of post-transplant complications. We carried out a non-systematic, narrative literature review aimed at describing the main indications, contraindications, performance characteristics and safety profile of interventional pulmonology techniques in the context of lung transplantation. We highlighted the role of bronchoscopy during donor evaluation and described the debated role of surveillance bronchoscopy (with bronchoalveolar lavage and transbronchial biopsy) to detect early rejection, infections and airways complications. The conventional (transbronchial forceps biopsy) and the new techniques (i.e. cryobiopsy, biopsy molecular assessment, probe-based confocal laser endomicroscopy) can detect and grade rejection. Several endoscopic techniques (e.g. balloon dilations, stent placement, ablative techniques) are employed in the management of airways complications (ischemia and necrosis, dehiscence, stenosis and malacia). First line pleural interventions (i.e. thoracentesis, chest tube insertion, indwelling pleural catheters) may be useful in the context of early and late pleural complications occurring after lung transplantation. High quality studies are advocated to define endoscopic standard protocols and thus help improving long-term prognostic outcomes of lung transplant recipients.

Acute rejection and post lung transplant surveillance

Purpose

The purpose of this review is to summarize the current evidence on the evaluation and treatment of acute rejection after lung transplantation.

Results

Despite significant progress in the field of transplant immunology, acute rejection remains a frequent complication after transplantation. Almost 30% of lung transplant recipients experience at least one episode of acute cellular rejection (ACR) during the first year after transplant. Acute cellular rejection, lymphocytic bronchiolitis, and antibody-mediated rejection (AMR) are all risk factors for the subsequent development of chronic lung allograft dysfunction (CLAD). Acute cellular rejection and lymphocytic bronchiolitis have well-defined histopathologic diagnostic criteria and grading. The diagnosis of antibody-mediated rejection after lung transplantation requires a multidisciplinary approach. Antibody-mediated rejection may cause acute allograft failure.

Conclusions

Acute rejection is a risk factor for development of chronic rejection. Further investigations are required to better define risk factors, surveillance strategies, and optimal management strategies for acute allograft rejection.

Surveillance for acute cellular rejection after lung transplantation

Acute cellular rejection (ACR) is a common complication following lung transplantation (LTx), affecting almost a third of recipients in the first year. Established, comprehensive diagnostic criteria exist but they necessitate allograft biopsies which in turn increases clinical risk and can pose certain logistical and economic problems in service delivery. Undermining these challenges further, are known problems with inter-observer interpretation of biopsies and uncertainty as to the long-term implications of milder or indeed asymptomatic episodes. Increased risk of chronic lung allograft dysfunction (CLAD) has long been considered the most significant consequence of ACR. Consensus is lacking as to whether this applies to mild ACR, with contradictory evidence available. Given these issues, research into alternative, minimal or non-invasive biomarkers represents the main focus of research in ACR. A number of potential markers have been proposed, but none to date have demonstrated adequate sensitivity and specificity to allow translation from bench to bedside.

The utility of bronchoscopy in immunocompromised patients: a review

Bronchoscopy is an important tool for the diagnosis of pulmonary disorders in immunocompromised patients. The addition of biopsies to bronchoalveolar lavage improves the diagnostic yield of non-infectious etiologies, although the underlying etiology of the immunocompromised state must be considered and may be influential. Certain unknowns remain, including timing of bronchoscopy and its impact on medical management and mortality. The ongoing role of non-invasive testing for infectious complications prior to bronchoscopy also remains to be defined. This review addresses the role of bronchoscopy in immunocompromised states related to underlying hematologic malignancies, prescription drug use or chemotherapy, and other disorders that predispose patients to infectious or non-infectious pulmonary diseases.

Detection, classification, and management of rejection after lung transplantation

Rejection is a major complication following lung transplantation. Acute cellular rejection, lymphocytic bronchiolitis, and antibody-mediated rejection (AMR) are all risk factors for the subsequent development of chronic lung allograft dysfunction (CLAD). Acute cellular rejection and lymphocytic bronchiolitis have well defined histopathologic diagnostic criteria and grading. Diagnosis of AMR requires a multidisciplinary approach. CLAD is the major barrier to long-term survival following lung transplantation. The most common phenotype of CLAD is bronchiolitis obliterans syndrome (BOS) which is defined by a persistent obstructive decline in lung function. Restrictive allograft dysfunction (RAS) is a second phenotype of CLAD and is associated with a worse prognosis. This article will review the diagnosis, staging, clinical presentation, and treatment of acute rejection, AMR, and CLAD following lung transplantation.

Parenteral administration of oral medications in lung transplant recipients: An underrecognized problem

Microcrystalline cellulose (MCC) is an insoluble material commonly used as a binder and filler in oral medications. Identification of pulmonary intravascular deposition of MCC in transbronchial biopsies from lung transplant (LT) recipients following parenteral injection of oral medications has only been reported once. A search of our surgical pathology electronic database was performed from January 1, 2000 to November 1, 2017 using the text "transplant transbronchial." The diagnosis field for all cases retrieved was then searched for the text "cellulose." These cases were queried for patient demographics and outcomes. Between January 1, 2000 and November 1, 2017, 1558 lung transplants were performed in 1476 individual patients at our institution; 12 were identified to have MCC in their lung tissue. Patients with MCC identified on biopsies were more likely to be transplanted for cystic fibrosis versus other indications and younger versus older. MCC identified in 2 of our cases was favored to be donor derived. Of the 12 patients, 6 (50%) are deceased. MCC within the pulmonary vasculature may be an indicator of increased complications, mortality, or shortened survival in LT recipients. Detecting intravascular MCC and distinguishing it from aspirated foreign material can be challenging. Awareness of the differential diagnosis for pulmonary foreign material is of paramount importance for the pathologist.

Prophylactic epinephrine for the prevention of transbronchial lung biopsy-related bleeding in lung transplant recipients (PROPHET) study: a protocol for a multicentre randomised, double-blind, placebo-controlled trial

INTRODUCTION

Transbronchial lung biopsy (TBLB) is frequently performed in single-lung and double-lung transplant recipients for evaluation of clinical and radiological findings as well as routine surveillance for acute cellular rejection. While rates of clinically significant TBLB-related haemorrhage are <1% for all comers, the incidence in lung transplant recipients is reported to be higher, presumably due to persistent allograft inflammation and alterations in allograft blood flow. While routinely performed by some bronchoscopists, the efficacy and safety profile of prophylactic administration of topical intrabronchial diluted epinephrine for the prevention of TBLB-related haemorrhage has not been explored in a prospective manner.

METHODS AND ANALYSIS

In this randomised, double-blind, placebo-controlled multicentre trial (PROPHET Study), single-lung and double-lung transplant adult recipients from participating institutions who are scheduled for bronchoscopy with TBLB for clinical indications will be identified. Potential participants who meet inclusion and exclusion criteria and sign an informed consent will be randomised to receive either diluted epinephrine or placebo prior to performance of TBLB. The degree of TBLB-related haemorrhage will be graded by the performing bronchoscopist as well as independent observers. The primary analysis will compare the rates of severe and very severe bleeding in participants treated with epinephrine or placebo. The study will also evaluate the safety profile of prophylactic topical epinephrine including the occurrence of serious cardiovascular and haemodynamic adverse events. Additional secondary outcomes to be explored include rates of non-severe TBLB-related haemorrhage, overall yield of the bronchoscopic procedure and non-serious cardiovascular and haemodynamic adverse effects.

ETHICS AND DISSEMINATION

The study procedures were reviewed and approved by institutional review boards in participating institutions. This study is being externally monitored, and a data and safety monitoring committee has been assembled to monitor patient safety and to evaluate the efficacy of the intervention. The results of this study will be published in peer-reviewed scientific journals and presented at relevant academic conferences.

TRIAL REGISTRATION NUMBER

NCT03126968; Pre-results.

Acute rejection

Despite induction immunosuppression and the use of aggressive maintenance immunosuppressive regimens, acute allograft rejection following lung transplantation is still a problem with important diagnostic and therapeutic challenges. As well as causing early graft loss and mortality, acute rejection also initiates the chronic alloimmune responses and airway-centred inflammation that predispose to bronchiolitis obliterans syndrome (BOS), also known as chronic lung allograft dysfunction (CLAD), which is a major source of morbidity and mortality after lung transplantation. Cellular responses to human leukocyte antigens (HLAs) on the allograft have traditionally been considered the main mechanism of acute rejection, but the influence of humoral immunity is increasingly recognised. As with other several other solid organ transplants, antibody-mediated rejection (AMR) is now a well-accepted and distinct clinical entity in lung transplantation. While acute cellular rejection (ACR) has defined histopathological criteria, transbronchial biopsy is less useful in AMR and its diagnosis is complicated by challenges in the measurement of antibodies directed against donor HLA, and a determination of their significance. Increasing awareness of the importance of non-HLA antigens further clouds this issue. Here, we review the pathophysiology, diagnosis, clinical presentation and treatment of ACR and AMR in lung transplantation, and discuss future potential biomarkers of both processes that may forward our understanding of these conditions.

Acute Rejection and Antibody-Mediated Rejection in Lung Transplantation

Despite advances in immunosuppression over the past 25 years, acute cellular rejection remains a common complication early after lung transplantation. Although acute cellular rejection has often not resulted in clinical signs or symptoms of allograft dysfunction, it has been widely recognized as a strong independent risk factor for the development of chronic rejection, emphasizing its clinical significance. In recent years, the role of humoral immunity in lung rejection has been increasingly appreciated, and antibody-mediated rejection is now recognized as a form of rejection that may result in allograft failure.

A Randomized Controlled Trial of a Novel Sheath Cryoprobe for Bronchoscopic Lung Biopsy in a Porcine Model

BACKGROUND

Transbronchial forceps biopsy (FBx) has been the preferred method for obtaining bronchoscopic lung biopsy specimens. Cryoprobe biopsy (CBx) has been shown to obtain larger and higher quality samples, but is limited by its inability to retrieve the sample through the working channel of the bronchoscope, requiring the bronchoscope to leave the airway for sample retrieval.

OBJECTIVE

We evaluated a novel device using a sheath cryobiopsy (SCBx). This method allows for specimen retrieval through the working channel of the bronchoscope, with the scope remaining inside the airway.

METHODS

This prospective, randomized controlled, single-blinded porcine study compared a 1.1-mm SCBx probe, a 1.9-mm CBx probe, and 2.0-mm FBx forceps. Assessment of histologic accessibility, sample quantity and quality, number of attempts to acquire and retrieve samples, cryoprobe activation time, fluoroscopy activation time, technical feasibility, and complications were compared.

RESULTS

Samples adequate for standard pathologic processing were retrieved with 82.1% of the SCBx specimens, 82.9%% of the CBx specimens, and 30% of the FBx specimens. The histologic accessibility of both SCBx (P = .0002) and CBx (P = .0003) was superior to FBx. Procedure time for FBx was faster than for both SCBx and CBx, but SCBx was significantly faster than CBx (P < .0001). Fluoroscopy time was lower for both SCBx and CBx compared with FBx. There were no significant bleeding events.

CONCLUSIONS

SCBx is a feasible technique providing a higher quality lung biopsy specimen compared with FBx and can successfully be retrieved through the working channel. Human studies are needed to further assess this technique with additional safety data.

Bronchoscopic procedures and lung biopsies in pediatric lung transplant recipients

Bronchoscopy remains a pivotal diagnostic and therapeutic intervention in pediatric patients undergoing lung transplantation (LTx). Whether performed as part of a surveillance protocol or if clinically indicated, fibre-optic bronchoscopy allows direct visualization of the transplanted allograft, and in particular, an assessment of the patency of the bronchial anastomosis (or tracheal anastomosis following heart-lung transplantation). Additionally, bronchoscopy facilitates differentiation of infective processes from rejection episodes through collection and subsequent assessment of bronchoalveolar lavage (BAL) and transbronchial biopsy (TBBx) samples. Indeed, the diagnostic criteria for the grading of acute cellular rejection is dependent upon the histopathological assessment of biopsy samples collected at the time of bronchoscopy. Typically, performed in an out-patient setting, bronchoscopy is generally a safe procedure, although complications related to hemorrhage and pneumothorax are occasionally seen. Airway complications, including stenosis, malacia, and dehiscence are diagnosed at bronchoscopy, and subsequent management including balloon dilatation, laser therapy and stent insertion can also be performed bronchoscopically. Finally, bronchoscopy has been and continues to be an important research tool allowing a better understanding of the immuno-biology of the lung allograft through the collection and analysis of collected BAL and TBBx samples. Whilst new investigational tools continue to evolve, the simple visualization and collection of samples within the lung allograft by bronchoscopy remains the gold standard in the evaluation of the lung allograft. This review describes the use and experience of bronchoscopy following lung transplantation in the pediatric setting.

Heart-lung transplantation: pediatric indications and outcomes

As indications for heart-lung transplant (HLT) have changed to some degree in the past 30 years, this treatment is being used less frequently in children due to more advanced care of severe heart and lung disease. This is fortunate as the outcomes for HLT are poor compared to other solid organ transplants and this is mainly due to the poorer outcome of the lung graft.

[Heart and combined heart-lung transplantation. Indications, chances and risks]

Orthotopic heart transplantation (HTX) is nowadays the worldwide accepted gold standard for the treatment of terminal heart failure. The main indications for HTX are non-ischemic dilatative (54%) and ischemic (37%) heart failure. In the acute phase after HTX the survival rate is approximately 90%. Good short and long-term results with survival rates ranging from 81% after 1 year to more than 50% after 11 years demonstrate that there is currently no real treatment alternative to HTX for treatment of end-stage heart failure. In the case of irreversible pulmonary hypertension in combination with end-stage heart failure or complex congenital heart syndromes, a combined heart and lung transplantation (HLTX) is necessary. Compared with HTX the short-term survival of HLTX is reduced, mostly for technical reasons. Improved long-term results after HTX and HLTX are a result of highly specialized transplantation units and effective immunosuppression. However, a major problem is the shortage of organ donors in Germany and the resulting long waiting times for patients with frequently occurring blood groups of up to 10 months for transplantation. The consequence of the latter is the ever increasing number of implanted cardiac assist devices in patients not only as a bridge to transplant but also as destination therapy.

Surveillance transbronchial biopsies in infant lung and heart-lung transplant recipients

There are limited published data on surveillance TBB for the identification of allograft rejection in infants after lung or heart-lung transplantation. We performed a retrospective review of children under one yr of age who underwent lung or heart-lung transplant at our institution. Since 2005, four infants were transplanted (three heart-lung and one lung). The mean age (±s.d.) at the time of transplant was 5.5 ± 2.4 (range 3-8) months. A total of 16 surveillance TBB procedures were completed in both inpatient and outpatient settings, with a range of 3-7 performed per patient. A minimum of five acceptable tissue pieces with expanded alveoli were obtained in 81% (13/16) of TBB procedures and a minimum of three pieces in 88% (14/16). There was no evidence of acute allograft rejection in 88% (14/16) of TBB procedures. One TBB procedure yielded two tissue specimens demonstrating A2 acute allograft rejection. One TBB procedure failed to yield tissue with sufficient alveoli. Additionally, B-grade assessment identified B0 in 50% (8/16), B1R in 12% (2/16), and BX (ungradeable or insufficient sample) in 38% (6/16) of biopsy procedures, respectively. In conclusion, TBB may be safely performed as an inpatient and outpatient procedure in infant lung and heart-lung transplant recipients and may provide adequate tissue for detecting acute allograft rejection and small airway inflammation.

Diagnostic bronchoscopy in solid-organ and hematopoietic stem cell transplantation

Fiberoptic bronchoscopy is a valuable diagnostic tool in solid-organ and hematopoietic stem cell transplant recipients presenting with a range of pulmonary complications. This article provides a comprehensive overview of the utility and potential adverse effects of diagnostic bronchoscopy for transplant recipients. Recommendations are offered on the selection of patients, the timing of bronchoscopy, and the samples to be obtained across the spectrum of suspected pulmonary complications of transplantation. Based on review of the literature, the authors recommend early diagnostic bronchoscopy over empiric treatment in transplant recipients with evidence of certain acute, subacute, or chronic pulmonary processes. This approach may be most critical when an underlying infectious etiology is suspected. In the absence of prompt diagnostic information on which to base effective treatment, the risks associated with empiric antimicrobial therapy, including medication side effects and the development of antibiotic resistance, compound the potential harm of delaying targeted management.

Flexible bronchoscopy

Although bronchoscopy technology continues to evolve at a fairly rapid pace, basic procedures, such as bronchoalveolar lavage, transbronchial lung biopsy, and transbronchial needle aspiration, continue to play a paramount role in the diagnosis of bronchopulmonary diseases. Pulmonologists should be trained in these basic bronchoscopic procedures.

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.

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.

Obliterative Bronchiolitis

Obliterative bronchiolitis (OB) is a condition characterized by inflammation and fibrosis of the bronchiolar walls resulting in narrowing or obliteration of the bronchiolar lumen. The most common causes are childhood lower respiratory tract infection, hematopoietic stem cell or lung and heart-lung transplantation, and toxic fume inhalation. The most frequent clinical manifestations are progressive dyspnea and dry cough. Pulmonary function tests demonstrate airflow obstruction and air trapping. Radiographic manifestations include reduction of the peripheral vascular markings, increased lung lucency, and overinflation. The chest radiograph, however, is often normal. High-resolution CT is currently the imaging modality of choice in the assessment of patients with suspected or proven OB. The characteristic findings on high-resolution CT consist of areas of decreased attenuation and vascularity (mosaic perfusion pattern) on inspiratory scans and air trapping on expiratory scans. Other CT findings of OB include bronchiectasis and bronchiolectasis, bronchial wall thickening, small centrilobular nodules, and three-in-bud opacities. Recent studies suggest that hyperpolarized ³He-enhanced magnetic resonance imaging may allow earlier recognition of obstructive airway disease and therefore may be useful in the diagnosis and follow-up of patients with OB.

Successful lung transplantation for adolescents at a hospital for adults

OBJECTIVE

To describe the results of lung transplantation (LTx) in adolescents at a hospital for adults.

DESIGN AND SETTING

Prospective cohort study set in an LTx unit at an adult tertiary referral hospital from 1991 to 2006.

PATIENTS

37 consecutive adolescent lung transplant recipients including 13 males and 24 females (mean age, 16.7+/-2.0 [SD] years; range 12-19 years) who received heart-lung (six patients) or bilateral LTx (31 patients) for cystic fibrosis (29), congenital heart disease (four), acute respiratory failure (two), or another disorder (two). Two patients were transplanted after invasive ventilation, five after non-invasive ventilation and two after extracorporeal membrane oxygenation.

MAIN OUTCOME MEASURES

Overall survival compared with an adult cohort; survival free of bronchiolitis obliterans syndrome (BOS); overall and BOS-free survival in those transplanted before and after January 2000.

RESULTS

Mean waiting time was 273 days (range, 5-964 days; median, 163 days), mean donor age was 28 years (range, 9-53 years). Median inpatient stay was 11 days (range, 7-94 days). Mean follow-up was 1540+/-1357 days (range, 35-5163 days). The 5-year survival rate for the 16 patients transplanted before January 2000 was 38%, versus 74% for the 21 transplanted since January 2000 (P=0.05; Mantel-Cox). Overall, 18 of 35 evaluable patients developed BOS. Only BOS was associated with an increased mortality risk (P<0.01).

CONCLUSION

LTx may be performed successfully in adolescents at a hospital for adults.

Lung transplantation for cystic fibrosis: Current concepts and one center's experience

BACKGROUND

Although new approaches to the treatment of patients with cystic fibrosis (CF) are significantly prolonging their lives, most patients will eventually develop respiratory failure due to progressive bronchiectasis caused by chronic lung infection and inflammation and die from to respiratory failure. We examined our center's (University of Wisconsin Hospital and Clinics) experience with lung transplantation for patients with CF and reviewed the literature to examine current and evolving approaches to transplantation for this indication.

METHODS

We reviewed all published literature pertaining to lung transplantation for CF through 2006, and we reviewed all aspects of transplantation for patients with CF at our institution from 1994 to 2005.

RESULTS

Major complications following lung transplantation include acute rejection, bacterial infection, and bronchiolitis obliterans. Five-year survival at UWHC (Kaplan-Meier) is 67%, and survival was not adversely affected by transplanting patients receiving mechanical ventilation. The major cause of death for transplant recipients was bronchiolitis obliterans syndrome (BOS).

CONCLUSIONS

Lung transplantation for CF is associated with acceptable survival rates and can improve quality of life. Lung transplant should be offered to all patients with advanced CF lung disease if they meet currently accepted inclusion and exclusion criteria.

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.

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.

Lung transplantation for chronic obstructive pulmonary disease at St Vincent's Hospital

BACKGROUND

Lung transplantation (LTx) offers selected patients with end-stage chronic obstructive pulmonary disease (COPD) an improved quality of life and possibly enhanced survival.

AIM

To determine local outcomes of LTx for COPD we analysed 173 consecutive heart-LTx (n = 8), single LTx (SLTx; n = 99) and bilateral LTx (BLTx; n = 66) carried out at a single institution during 1989-2003 for smoking-related emphysema (E) (n = 112) and emphysema related to alpha-1 antitrypsin deficiency (AATD) (n = 61).

METHODS

There were 98 men and 75 women with a mean age of 50 +/- 6 years (standard deviation) (range 32-63 years). Median waiting time was 113 days (interquartile range (IQR) 50-230 days), and median inpatient stay was 13 days (IQR 9-21 days).

RESULTS

Perioperative survival (30 days) was 95% with deaths from sepsis (n = 5), cerebrovascular accident (n = 3) and multiorgan failure (n = 1). Mean follow-up period was 1693 +/- 1302 days (2-4,805 days). The 1-, 5- and 10-year survivals (%) were similar for patients with E and AATD (P = 0.480 log rank) at 86 +/- 5, 57 +/- 7 and 31 +/- 11, respectively, but 1- and 5-year survivals for E were higher after BLTx than after SLTx (97 +/- 2 and 81 +/- 8 vs 85 +/- 4 and 47 +/- 6) (P = 0.015). Pretransplant body mass index, forced expiratory volume in 1 second, forced vital capacity, PaCO(2), PaO(2), six-minute walk distance, home oxygen use, age, sex, cytomegalovirus donor-recipient mismatch, cardiopulmonary bypass use, year of transplant and ischaemic time did not influence survival after LTx. Increasing donor age was a survival risk factor for patients with E but not for those with AATD (hazard ratio 1.043; 95%confidence interval 1.014-1.025).

CONCLUSION

Survival after LTx for COPD is similar to survival for other forms of solid organ transplantation, in part reflecting risk factor management.

Sedative Drug Requirements during Bronchoscopy Are Higher in Cystic Fibrosis after Lung Transplantation

BACKGROUND

We noted that patients with cystic fibrosis tended to need higher doses of sedatives during bronchoscopy. We undertook this study to assess the sedative drug doses administered during bronchoscopy in lung transplant recipients and to assess if there is a change in the dosage requirements over time following lung transplantation.

METHODS

In all, 773 transbronchial biopsy procedures performed via flexible bronchoscopy were analyzed in 140 consecutive lung transplant recipients. Conscious sedation was achieved with intermittent boluses of intravenous midazolam and fentanyl. Intravenous propofol boluses of 10 to 30 mg were administered when optimal sedation was not achieved with midazolam doses of 0.20 to 0.25 mg/kg and fentanyl 2 to 2.5 micrograms/kg.

RESULTS

Mean doses of midazolam and fentanyl administered were 0.15+/-0.07 mg/kg (range 0.02 to 0.44 mg/kg) and 1.8+/-0.8 micrograms/kg (range 0.1 to 6.67 micrograms/kg) respectively. Midazolam and fentanyl doses administered to patients with cystic fibrosis were the highest compared to those with other disease types (P<0.0001). Examining the sedative doses administered over time following transplantation, there was a significant linear (P<0.001) and quadratic (P=0.0023) effect of time for midazolam and a significant linear (P=0.003) and a trend (P=0.08) for a quadratic effect for fentanyl. Propofol was effectively used in seven lung transplant recipients in whom adequate sedation could not be achieved with high doses of midazolam and fentanyl.

CONCLUSIONS

There is an increase in sedative drug requirement with time for both midazolam and fentanyl after transplantation, which is significantly higher in patients with cystic fibrosis.

HLA-specific antibodies are risk factors for lymphocytic bronchiolitis and chronic lung allograft dysfunction

Bronchiolitis obliterans syndrome (BOS) represents a major limitation in lung transplantation. While acute rejection is widely considered the most important risk factor for BOS, the impact of HLA-specific antibodies is less understood. Of 51 lung recipients who were prospectively tested during a 4.2 +/- 1.6-year period, 14 patients developed HLA-specific antibodies. A multi-factorial analysis was performed to correlate the prevalence of BOS with HLA antibodies, persistent-recurrent acute rejection (ACR-PR), lymphocytic bronchiolitis, and HLA-A, -B, and -DR mismatches. HLA-specific antibodies were associated with ACR-PR (10/14 vs. 11/37 with no antibodies, p < 0.05), lymphocytic bronchiolitis (8/14 vs. 10/37, p < 0.05), and BOS (10/14, vs. 9/37, p < 0.005). Other risk factors for BOS were: lymphocytic bronchiolitis (13/18 vs. 6/33 with no lymphocytic bronchiolitis, p < 0.0001), ACR-PR (12/21 vs. 7/30 with no ACR-PR, p < 0.05), and the number of HLA-DR mismatches (1.7 +/- 0.48 in BOS vs. 1.2 +/- 0.63 without BOS, p < 0.05). The presence of antibodies exhibited a cumulative effect on BOS when it was associated with either lymphocytic bronchiolitis or ACR-PR. The complex relationship between the development of HLA antibodies and acute and chronic lung allograft rejection determines the importance of post-transplant screening for HLA-specific antibodies as a prognostic element for lung allograft outcome.

Treated Cytomegalovirus Pneumonia Is Not Associated with Bronchiolitis Obliterans Syndrome

The association of cytomegalovirus (CMV) infection with the development of bronchiolitis obliterans syndrome (BOS) is unclear. We studied 341 lung transplant recipients to assess whether histopathologically diagnosed CMV pneumonia treated with ganciclovir was a risk factor for development of BOS and patient survival. We also analyzed the relationship between CMV donor/recipient serologic status and BOS plus the temporal association between acute rejection and CMV pneumonia. Freedom from BOS for patients with (n = 151) and without (n = 190) CMV pneumonia was 83 and 90% (1 year), 52 and 56% (3 years), and 29 and 38% (5 years), respectively (p = 0.2660). Cumulative survival of patients with and without CMV pneumonia was 90 and 93% (1 year), 70 and 74% (3 years), and 58 and 63% (5 years), respectively (p = 0.1811). There were no significant differences in either development of BOS or patient survival with any combination of donor/recipient serostatus for CMV. Acute rejection occurred in the month preceding CMV pneumonia in 62 of 193 (32%) cases. Histopathologically confirmed CMV pneumonia treated with ganciclovir is not a risk factor for BOS or patient survival, nor is any particular CMV serologic donor/recipient group. CMV pneumonia often follows acute rejection, perhaps as a result of augmented immunosuppression.

Association of minimal rejection in lung transplant recipients with obliterative bronchiolitis

The clinical significance of minimal acute rejection (grade A1) in lung transplant recipients is unknown. We prospectively analyzed 1,159 transbronchial lung biopsies in 184 patients. Two hundred seventy-nine biopsies in 128 participants confirmed A1 histology at a mean postoperative day of 229 +/- 340. Sixty four of 255 surveillance A1 lesions progressed to high-grade acute rejection by 3 months of follow-up, whereas 40 developed new lymphocytic bronchiolitis. Twenty-four A1 biopsies were symptomatic, with only two cases progressing to high-grade rejection after steroid therapy. Seventy-eight of 184 patients experienced multiple (> or = 2) A1 biopsies in the first 12 months after transplant. Bronchiolitis obliterans syndrome developed in 68% of patients with multiple A1 lesions at a mean of 599 +/- 435 days, compared with 43% of patients with one or less A1 lesions at a mean of 819 +/- 526 (p = 0.022). Eighteen patients experienced multiple A1 biopsies after transplant in the absence of high-grade rejection episodes yet also developed earlier obliterative bronchiolitis (456 +/- 245 days, p = 0.020). We conclude that for A1 transbronchial lung biopsies, the conventional treatment of observation only is now challenged even in patients who are asymptomatic. Patients who experience multiple A1 lesions develop an earlier onset of obliterative bronchiolitis and may warrant alternative immunosuppressive strategies.

The use of multiple transbronchial biopsies as the standard approach to evaluate lung allograft rejection

Flexible bronchoscopy with transbronchial biopsy (TBB) is routinely performed in adult and pediatric lung transplant recipients. The clinical signs and symptoms of acute cellular rejection (ACR) are often identical to those of infection. TBB is a fairly sensitive and specific tool in which to diagnose ACR and can be performed safely in children of all ages. The utility of TBB is unquestioned during periods of worsening clinical symptoms. The utility of TBB for routine surveillance of the allograft remains unproven. The data suggests that during the first 4-6 months post-transplant there is a high incidence of clinically silent ACR. The significance of subclinical rejection in lung transplantation is unknown. Randomized, controlled trials are required to determine if multiple surveillance TBB, can impact the incidence of obliterative bronchiolitis.

Everolimus and mycophenolate mofetil are potent inhibitors of fibroblast proliferation after lung transplantation1

BACKGROUND

Dysregulated fibroblast proliferation is thought to play an important role in the progression of bronchiolitis obliterans (BO) after lung transplantation. Augmented immunosuppression is often used to treat BO. We investigated the effect of methylprednisolone (mPRED), cyclosporine A (CsA), tacrolimus (FK506), azathioprine (AZA), mycophenolate mofetil (MMF), and everolimus (rapamycin derivative [RAD]) on the proliferative capacity of fibroblasts cultured from transbronchial biopsies of lung transplant recipients.

METHODS

Primary cultures of human lung fibroblasts were obtained from 14 transbronchial biopsies of lung transplant recipients. Subconfluent cells were serum starved for 24 hr followed by growth stimulation in the presence or absence of the respective drug in six concentrations ranging as follows: 0.01 to 100 mg/L for mPRED; 0.01 to 50 mg/L for CsA and AZA; 0.001 to 5 mg/L for FK506 and MMF; and 0.00001 to 1 mg/L for RAD. Proliferation was quantified by [3H]thymidine incorporation and direct cell count. A toxic drug effect was excluded by trypan blue.

RESULTS

Drug concentrations (mg/L) causing a 50% inhibition of fibroblast proliferation were mPRED 4; CsA 20; FK506 0.3; AZA 7; MMF 0.3; and RAD 0.0006. Drug concentrations (mg/L) causing inhibition of fetal bovine serum-induced proliferation were mPRED 60; CsA 45; FK506 3; AZA 35; MMF 1; and RAD 0.003.

CONCLUSIONS

RAD and MMF were the most potent antifibroproliferative drugs and were effective at concentrations achieved clinically, supporting their use for the treatment of patients with early BO. Our method holds promise as an in vitro model to assess the likely in vivo responses of human lung fibroblasts to specific immunosuppressive drugs.

Transplant histopathology for the general histopathologist

The number of patients undergoing solid organ transplants and surviving long-term has increased enormously in the last 10 years. This means that pathologists in non-specialist transplant centres are increasingly involved in the interpretation of biopsy and autopsy material from allograft recipients. This includes evaluation of allograft histology, or specimens from other native tissues, which nonetheless still have to be assessed in the setting of transplantation and immunosuppressive therapy. In this first review article we will provide an overview of the pathology of lung transplantation, and briefly describe heart and pancreatic transplants, as well as aspects of general surgical pathology and the role of the autopsy in these patients.

Acute allograft rejection after lung transplantation: diagnosis and therapy

Acute rejection remains a significant problem after lung transplantation. While it generally is a treatable condition, significant resources and therapies are directed toward its prevention and resolution. Its larger significance undoubtedly rests in its contribution to the pathogenesis of BOS. Significant questions regarding the origins of AR, the role of LBB, alternative histologic appearances of acute allograft injury, and optimal therapy remain. Controversy regarding the utility of surveillance bronchoscopy and preemptive treatment of occult AR persists because of lack of conclusive evidence. Future investigations might resolve these matters and provide more efficacious and less toxic therapies that will hopefully reduce the impact of chronic rejection and improve long-term outcomes.

Risk factors and management of bleeding associated with transbronchial lung biopsy in lung transplant recipients

The aim of this study was to assess specific risk factors associated with bleeding during transbronchial biopsy (TBBx) in lung transplant recipients. Risk factors analyzed included gender, type of transplant, acute rejection, bronchiolitis obliterans syndrome (BOS) status, infections, number of biopsies obtained per procedures, serum creatinine level and post-operative day since transplantation. The bronchoscope was not wedged to obtain TBBx and associated bleeding was managed using the "back-and-forth" technique. The severity of bleeding is shown to be independent of any specific risk factor and the back-and-forth technique described herein can be safely employed in lung transplant recipients to manage bleeding associated with TBBx performed without wedging of the bronchoscope.