Margaret Burke

Report from a consensus conference on antibody-mediated rejection in heart transplantation

BACKGROUND The problem of AMR remains unsolved because standardized schemes for diagnosis and treatment remains contentious. Therefore, a consensus conference was organized to discuss the current status of antibody-mediated rejection (AMR) in heart transplantation. METHODS The conference included 83 participants (transplant cardiologists, surgeons, immunologists and pathologists) representing 67 heart transplant centers from North America, Europe, and Asia who all participated in smaller break-out sessions to discuss the various topics of AMR and attempt to achieve consensus. RESULTS A tentative pathology diagnosis of AMR was established, however, the pathologist felt that further discussion was needed prior to a formal recommendation for AMR diagnosis. One of the most important outcomes of this conference was that a clinical definition for AMR (cardiac dysfunction and/or circulating donor-specific antibody) was no longer believed to be required due to recent publications demonstrating that asymptomatic (no cardiac dysfunction) biopsy-proven AMR is associated with subsequent greater mortality and greater development of cardiac allograft vasculopathy. It was also noted that donor-specific antibody is not always detected during AMR episodes as the antibody may be adhered to the donor heart. Finally, recommendations were made for the timing for specific staining of endomyocardial biopsy specimens and the frequency by which circulating antibodies should be assessed. Recommendations for management and future clinical trials were also provided. CONCLUSIONS The AMR Consensus Conference brought together clinicians, pathologists and immunologists to further the understanding of AMR. Progress was made toward a pathology AMR grading scale and consensus was accomplished regarding several clinical issues.

Diffuse idiopathic pulmonary neuroendocrine cell hyperplasia: an under-recognised spectrum of disease.

Aims and Methods: A review was undertaken of 19 patients diagnosed with diffuse idiopathic pulmonary neuroendocrine cell hyperplasia (DIPNECH) between 1992 and 2006. Results: Most patients were women (n = 15) and non-smokers (n = 16). Clinical presentation was either with symptomatic pulmonary disease (group 1; n = 9) or as an incidental finding during investigation for another disorder, most frequently malignant disease (group 2; n = 10). In group 1, cough and dyspnoea were the most frequent symptoms, with an average duration of 8.6 years before diagnosis. Both groups showed mainly stable disease without treatment, although one patient progressed to severe airflow obstruction and one was diagnosed at single lung transplantation. Mosaicism with nodule(s) was the typical pattern of DIPNECH on high-resolution computed tomography, but one case had normal imaging despite airflow obstruction. Lung function tests showed obstructive (n = 8), mixed (n = 3) or normal (n = 5, all group 2) physiology. Two patients underwent a bronchoalveolar lavage and showed a lymphocytosis (30%) with mild chronic bronchiolitis being seen in all biopsies. Tumourlets and associated typical carcinoids (n = 9) showed weak positivity for thyroid transcription factor-1. Three patients had atypical carcinoids, one with multiple endocrine neoplasia type 1 syndrome. Conclusions: DIPNECH is being increasingly recognised, probably because of an increase in the usage and accuracy of investigative imaging and increased awareness of the entity. Most cases remain stable over many years independent of the mode of presentation, although a few patients progress to severe airflow obstruction.

The 2013 International Society for Heart and Lung Transplantation Working Formulation for the standardization of nomenclature in the pathologic diagnosis of antibody-mediated rejection in heart transplantation

During the last 25 years, antibody-mediated rejection of the cardiac allograft has evolved from a relatively obscure concept to a recognized clinical complication in the management of heart transplant patients. Herein we report the consensus findings from a series of meetings held between 2010-2012 to develop a Working Formulation for the pathologic diagnosis, grading, and reporting of cardiac antibody-mediated rejection. The diagnostic criteria for its morphologic and immunopathologic components are enumerated, illustrated, and described in detail. Numerous challenges and unresolved clinical, immunologic, and pathologic questions remain to which a Working Formulation may facilitate answers.

2011 consensus statement on endomyocardial biopsy from the Association for European Cardiovascular Pathology and the Society for Cardiovascular Pathology.

The Association for European Cardiovascular Pathology and the Society for Cardiovascular Pathology have produced this position paper concerning the current role of endomyocardial biopsy (EMB) for the diagnosis of cardiac diseases and its contribution to patient management, focusing on pathological issues, with these aims: • Determining appropriate EMB use in the context of current diagnostic strategies for cardiac diseases and providing recommendations for its rational utilization • Providing standard criteria and guidance for appropriate tissue triage and pathological analysis • Promoting a team approach to EMB use, integrating the competences of pathologists, clinicians, and imagers.

Pulmonary veno-occlusive disease and pulmonary capillary hemangiomatosis: a clinicopathologic study of 35 cases.

Pulmonary veno-occlusive disease (PVOD) and pulmonary capillary hemangiomatosis (PCH) are rare causes of pulmonary hypertension, regarded by some as distinct entities. However, their presentations are similar and both are associated with poor prognoses. We therefore reviewed 38 specimens [autopsies (n=15), surgical biopsies (n=15), explants (n=7), and pneumonectomy (1 case)] from 35 patients diagnosed as either PVOD (n=30; av. age 34 y, range 4 to 68 y; 19M:11F) or PCH (n=5, av. age 42 y, ranging from 9 months to 60 years; 3M:2F) to assess their interrelationship. PCH was identified in 24 (73%) cases diagnosed as PVOD, either as perivenular foci or diffuse involvement of the pulmonary parenchyma. Other features seen in PVOD were arterial medial hypertrophy and/or intimal fibrosis (88%), hemosiderosis (79%), venulitis (12%), infarction (9%), interstitial fibrosis (sometimes as localized scars) (48%), and a mild lymphocytic infiltrate (67%). In cases diagnosed as PCH, 4 showed venous and arterial changes of PVOD. Cases with PCH also all showed a mild interstitial lymphocytic infiltrate but there was no venulitis or infarction. Capillary proliferation was particularly well demonstrated by CD34 immunostaining and predominantly involved the alveoli, but was also seen within walls of bronchi and pulmonary vessels. Our data suggest that in the majority of cases PCH represents a secondary angioproliferative process caused by postcapillary obstruction rather than a separate disease. The cause of the venous obliteration was not identified but the occasional identification of phlebitis suggests this plays a role in venous damage in some cases.

The ISHLT working formulation for pathologic diagnosis of antibody-mediated rejection in heart transplantation: Evolution and current status (2005-2011)

From the Department of Pathology, Stanford University, Stanford, California; Universita of Padua Medical School, Padua, Italy; Royal Brompton and Harefield NHS Trust, London, United Kingdom; Hopital Europeen Georges Pompidou, Paris, France; David Geffen School of Medicine at the University of California-Los Angeles, Los Angeles, California; Intermountain Medical Center, Salt Lake City, Utah; Queen Elizabeth Hospital, Birmingham, United Kingdom; University of Utah, Salt Lake City, Utah; Cleveland Clinic, Cleveland, Ohio; Papworth Hospital, Papworth, United Kingdom; Brigham & Women’s Hospital, Boston, Massachusetts; Cedars Sinai Heart Institute, Los Angeles, California; University of Maryland School of Medicine, Baltimore, Maryland.

High expression of endothelial nitric oxide synthase in plexiform lesions of pulmonary hypertension.

The pathogenesis of pulmonary hypertension (PH) remains poorly understood. Vasoconstriction, although likely to be a major factor in the disease, varies between patients and studies of a variety of vasoactive substances have sometimes yielded conflicting results. Amongst these substances, alteration of the nitric oxide (NO) system has been cited as a possible pathogenic factor but both reduction and elevation of the expression of endothelial NO‐synthase (eNOS) have been reported in pulmonary vessels. The present study has used immunocytochemistry with well‐characterized antibodies to eNOS to investigate its expression in lung tissue taken at transplantation from 44 patients with PH (22 primary, 22 secondary) and 12 non‐hypertensive controls. Semi‐quantitative assessment showed that although the levels of eNOS expression in pulmonary vessels were variable within both hypertensives and controls, a statistically significant (P<0·01) reduction of immunoreactivity was found in small arterioles from hypertensives compared with controls. In contrast, consistently strong expression of eNOS was seen in the endothelium of plexiform lesions in both the primary and the secondary PH patients. Although a decrease in the NO system of patients with PH has been reported, these findings show a distinct regional distribution of the enzyme with particularly high levels in plexiform lesions, a previously unreported observation, and offer a new perspective on the disease and on the evaluation of possible novel therapeutic approaches.

Pathology of pulmonary antibody-mediated rejection: 2012 update from the Pathology Council of the ISHLT

Gerald Berry, MD, Margaret Burke, FRCPath, Claus Andersen, MD, DMSc, Annalisa Angelini, MD, Patrick Bruneval, MD, Fiorella Calbrese, MD, Michael C. Fishbein, MD, Martin Goddard, FRCS, MRCPa, Ornella Leone, MD, Joseph Maleszewski, MD, Charles Marboe, MD, Dylan Miller, MD, Desley Neil, FRCPath, Robert Padera, MD, PhD, Doris Rassi, MBBS, MRCP, Monica Revello, MD, PhD, Alexandra Rice, FRCPath, Susan Stewart, FRCPath, and Samuel A Yousem, MD

Virulence of Burkholderia cepacia complex strains in gp91phox-/- mice.

In cystic fibrosis (CF), infection with Burkholderia cepacia complex (Bcc) strains may cause long‐term asymptomatic airway colonization, or severe lung infection leading to rapid pulmonary decline. To assess the virulence of Bcc strains, we established a lung infection model in mice with a null allele of the gene involved in X‐linked chronic granulomatous disease (CGD). CGD mice, challenged intratracheally with 103 cells of the epidemic Burkholderia cenocepacia strain J2315, died within 3 days from sepsis after bacteria had multiplied to 3.3 × 108 cells. Infected mice developed neutrophil‐dominated lung abscesses. Other B. cenocepacia strains and a B. cepacia strain were less virulent and one B. multivorans and one B. vietnamensis CF isolate were both avirulent. Bcc mutants, defective in exopolysaccharide synthesis or quorum sensing revealed diminished or no abscess formation and mortality. Immunofluorescence staining of Bcc‐infected murine and CF lung tissues revealed colocalization of Bcc and neutrophils, suggesting Bcc persistence within neutrophils in CGD and CF. In vitro, Bcc cells were rapidly killed during aerobic neutrophil phagocytosis; however, the pathogens survived in neutrophils with blocked nicotinamide adenine dinucleotide phosphate oxidase activity and under anaerobic conditions. We conclude that the Bcc infection model in CGD mice is well suited for the assessment of Bcc virulence.

A duchenne muscular dystrophy gene hot spot mutation in dystrophin-deficient Cavalier King Charles Spaniels is amenable to exon 51 skipping

Background Duchenne muscular dystrophy (DMD), which afflicts 1 in 3500 boys, is one of the most common genetic disorders of children. This fatal degenerative condition is caused by an absence or deficiency of dystrophin in striated muscle. Most affected patients have inherited or spontaneous deletions in the dystrophin gene that disrupt the reading frame resulting in unstable truncated products. For these patients, restoration of the reading frame via antisense oligonucleotide-mediated exon skipping is a promising therapeutic approach. The major DMD deletion “hot spot” is found between exons 45 and 53, and skipping exon 51 in particular is predicted to ameliorate the dystrophic phenotype in the greatest number of patients. Currently the mdx mouse is the most widely used animal model of DMD, although its mild phenotype limits its suitability in clinical trials. The Golden Retriever muscular dystrophy (GRMD) model has a severe phenotype, but due to its large size, is expensive to use. Both these models have mutations in regions of the dystrophin gene distant from the commonly mutated DMD “hot spot”. Methodology/Principal Findings Here we describe the severe phenotype, histopathological findings, and molecular analysis of Cavalier King Charles Spaniels with dystrophin-deficient muscular dystrophy (CKCS-MD). The dogs harbour a missense mutation in the 5′ donor splice site of exon 50 that results in deletion of exon 50 in mRNA transcripts and a predicted premature truncation of the translated protein. Antisense oligonucleotide-mediated skipping of exon 51 in cultured myoblasts from an affected dog restored the reading frame and protein expression. Conclusions/Significance Given the small size of the breed, the amiable temperament and the nature of the mutation, we propose that CKCS-MD is a valuable new model for clinical trials of antisense oligonucleotide-induced exon skipping and other therapeutic approaches for DMD.