Helen Spencer

Transbronchial biopsies provide longitudinal evidence for epithelial chimerism in children following sex mismatched lung transplantation

Background: Recent reports have shown evidence of host derived parenchymal engraftment in several human allografts including the lung, leading to speculation that stem cell therapy may be useful for lung repair in diseases such as cystic fibrosis (CF). To date, previous studies have looked at single surgical or autopsy specimens and no longitudinal studies have been reported. The aim of this study was to assess whether transbronchial biopsies could be used to study the time course of chimerism following lung transplantation. Methods: Specimens of archived transbronchial lung biopsies from five time points taken for clinical purposes from two boys who had received a sex mismatched heart-lung transplant for end stage CF were examined. Sections were dual stained for cytokeratin (epithelium) and a mixture of leucocyte common antigen and CD68 for inflammatory cells. Co-localisation of cells containing a Y chromosome was confirmed by fluorescent in situ hybridisation. Results: Evidence of chimerism was found in up to 6.6% of epithelial cells in bronchial (median 1.4% (range 0–6.6)) and alveolar (median 3.6% (range 2.3–5.5) tissue without apparent evidence of fusion. This engraftment was seen as early as 3 weeks and remained relatively constant up to 37 months. Conclusions: This study has demonstrated proof of principle for long term chimerism in lung epithelium. Transbronchial biopsies may provide a new method for studying the kinetics of stem cell engraftment in the lung.

Lung Transplantation for Cystic Fibrosis

Lung transplantation is a complex, high-risk, potentially life-saving therapy for the end-stage lung disease of cystic fibrosis (CF). The decision to pursue transplantation involves comparing the likelihood of survival with and without transplantation as well as assessing the effect of wait-listing and transplantation on the patients quality of life. Although recent population-based analyses of the US lung allocation system for the CF population have raised controversies about the survival benefits of transplantation, studies from the United Kingdom and Canada have suggested a definite survival advantage for those receiving transplants. In response to these and other controversies, leaders in transplantation and CF met together in Lansdowne, Virginia, to consider the state of the art in lung transplantation for CF in an international context, focusing on advances in surgical technique, measurement of outcomes, use of prognostic criteria, variations in local control over listing, and prioritization among the United States, Canada, the United Kingdom, and The Netherlands, patient adherence before and after transplantation and other issues in the broader context of lung transplantation. Finally, the conference members carefully considered how efforts to improve outcomes for lung transplantation for CF lung disease might best be studied. This Roundtable seeks to communicate the substance of our discussions.

Stitching and switching: the impact of discontinuous lung function reference equations

To the Editors: In order to distinguish the effects of lung disease from those of normal growth and development, lung function is expressed in comparison with reference data, with forced expiratory volume in 1 s (FEV1) commonly being presented as % predicted. FEV1 % pred has been identified as being of prognostic value in cystic fibrosis (CF), such that an FEV1 of 20% from baseline determined by the average of two measurements made ≥3 weeks apart. Continuing to monitor FEV1 % pred after the development of BOS has also been shown to provide important insight into the patient’s prognosis and therapeutic options [2]. Given that FEV1 % pred plays such a key role in the clinical management of a child with CF or any child who has undergone lung transplantation, it is imperative to ensure that it is measured and interpreted accurately. Although guidelines for standardised measurement of spirometry have been developed for both adults [3] and children [4], the decision on which spirometry reference equation to use, amongst the plethora available [5], varies widely. This situation is further complicated by …

Renal complications following lung and heart-lung transplantation

As survival improves after lung and heart-lung transplants, the long term detrimental impact of current management on renal function becomes more apparent as the number of non-renal solid organ transplant recipients on renal transplant waiting lists increases. Progressive chronic kidney disease (CKD) is a significant cause of morbidity and mortality in the transplant population. In this review we discuss the specific problems prior to lung or heart-lung transplant that predispose to CKD, as well as potential renal complications encountered during the peri- and post-transplant period. Significant acute and chronic nephrotoxicity is caused by calcineurin inhibitors (CNI). Mechanisms to decrease CNI exposure exist but have yet to be adopted in routine clinical care. Modifiable risk factors and the current screening and management approach taken at our institution are described. Pediatric nephrologists should be involved from an early stage. Future work will need to focus on identifying more accurate measures of renal function, given the limitations of current glomerular filtration rate estimation equations in a population where nutritional status may rapidly change post transplant. Multicentre studies of CNI minimisation strategies are required to guide future therapy that aims to minimise CKD development and progression in this vulnerable population.

Newer therapies for cystic fibrosis

Abstract Cystic fibrosis is the most common lethal inherited disease in Caucasians in the UK, with an incidence of approximately one in 2500 live births. It is a heterogeneous disease which reflects different mutations in the cystic fibrosis transmembrane conductance regulator gene, modifier genes and environmental influences. The median life expectancy of children with cystic fibrosis born in the UK is approximately 30 years. Longer survival is the result of improvements in basic therapies including airway clearance, aggressive use of antibiotics and optimizing nutrition. Care given in a specialist centre has also been shown to improve survival. Despite this progress, pulmonary disease still accounts for most of the morbidity and is the cause of death in over 90% of patients with cystic fibrosis. This review will focus on newer therapies aimed at pulmonary disease which are now being used in the clinical setting, and other novel therapies which are still at the research stage.

Persistent disruption of ciliated epithelium following paediatric lung transplantation

It is unclear whether ciliary function following lung transplantation is normal or not. Our aim was to study the ciliary function and ultrastructure of epithelium above and below the airway anastomosis and the peripheral airway of children following lung transplantation. We studied the ciliary beat frequency (CBF) and beat pattern, using high speed digital video imaging and ultrastructure by transmission electron microscopy, of bronchial epithelium from above and below the airway anastomosis and the peripheral airway of 10 cystic fibrosis (CF) and 10 non-suppurative lung disease (NSLD) paediatric lung transplant recipients. Compared to epithelium below the anastomosis, the epithelium above the anastomosis in the CF group showed reduced CBF (median (interquartile range): 10.5 (9.0–11.4) Hz versus 7.4 (6.4–9.2) Hz; p<0.01) and increased dyskinesia (median (IQR): 16.5 (12.9–28.2)% versus 42.2 (32.6–56.4)%; p<0.01). In both CF and NSLD groups, compared with epithelium above the anastomosis, the epithelium below the anastomosis showed marked ultrastructural abnormalities (median duration post-transplant 7–12 months). Ciliary dysfunction is a feature of native airway epithelium in paediatric CF lung transplant recipients. The epithelium below the airway anastomosis shows profound ultrastructural abnormalities in both CF and NSLD lung transplant recipients, many months after transplantation.

Children with cystic fibrosis are infected with multiple subpopulations of Mycobacterium abscessus with different antimicrobial resistance profiles

Background Children with cystic fibrosis (CF) can develop life-threatening infections of Mycobacterium abscessus. These present a significant clinical challenge, particularly when the strains involved are resistant to antibiotics. Recent evidence of within-patient subclones of M. abscessus in adults with CF suggests the possibility that within-patient diversity may be relevant for the treatment of pediatric CF patients. Methods We performed whole genome sequencing (WGS) on 32 isolates of M. abscessus from multiple body sites for two patients with CF undergoing treatment at Great Ormond Street Hospital, UK, in 2015. Results We found evidence of extensive diversity within patients over time. Clustering analysis of single nucleotide variants (SNVs) revealed that each patient harboured multiple subpopulations, which were differentially abundant between sputum, lung samples, chest wounds, and pleural fluid. Sputum isolates did not reflect overall within-patient diversity, including failing to detect subclones with mutations previously associated with macrolide resistance (rrl 2058/2059). Some variants were present at intermediate frequencies before lung transplant. The time of transplant coincided with extensive variation, suggesting that this event is particularly disruptive for the microbial community, but transplant did not clear the M. abscessus infection and both patients died as a result of this infection. Conclusions Isolates of M. abscessus from sputum do not always reflect the entire diversity present within the patient, which can include subclones with differing AMR profiles. Awareness of this phenotypic variability, with sampling of multiple body sites in conjunction with WGS, may be necessary to ensure the best treatment for this vulnerable patient group. Key point summary Children with cystic fibrosis undergoing lung transplant harbour multiple subpopulations of M. abscessus. Subpopulations can have different antimicrobial resistance genotypes. Sputum isolates do not reflect the genetic diversity within a patient.