Living-donor lobar lung transplantation for pulmonary alveolar proteinosis in an adult: report of a case

European Respiratory Society guidelines for the diagnosis and management of pulmonary alveolar proteinosis

BACKGROUND

Pulmonary alveolar proteinosis (PAP) is a rare syndrome caused by several distinct diseases leading to progressive dyspnoea, hypoxaemia, risk of respiratory failure and early death due to accumulation of proteinaceous material in the lungs. Diagnostic strategies may include computed tomography (CT) of the lungs, bronchoalveolar lavage (BAL), evaluation of antibodies against granulocyte-macrophage colony-stimulating factor (GM-CSF), genetic testing and, eventually, lung biopsy. The management options are focused on removing the proteinaceous material by whole lung lavage (WLL), augmentation therapy with GM-CSF, rituximab, plasmapheresis and lung transplantation. The presented diagnostic and management guidelines aim to provide guidance to physicians managing patients with PAP.

METHODS

A European Respiratory Society Task Force composed of clinicians, methodologists and patients with experience in PAP developed recommendations in accordance with the ERS Handbook for Clinical Practice Guidelines and the GRADE (Grading of Recommendations, Assessment, Development and Evaluations) approach. This included a systematic review of the literature and application of the GRADE approach to assess the certainty of evidence and strength of recommendations. The Task Force formulated five PICO (Patients, Intervention, Comparison, Outcomes) questions and two narrative questions to develop specific evidence-based recommendations.

RESULTS

The Task Force developed recommendations for the five PICO questions. These included management of PAP with WLL, GM-CSF augmentation therapy, rituximab, plasmapheresis and lung transplantation. Also, the Task Force made recommendations regarding the use of GM-CSF antibody testing, diagnostic BAL and biopsy based on the narrative questions. In addition to the recommendations, the Task Force provided information on the hierarchy of diagnostic interventions and therapy.

CONCLUSIONS

The diagnosis of PAP is based on CT and BAL cytology or lung histology, whereas the diagnosis of specific PAP-causing diseases requires GM-CSF antibody testing or genetic analysis. There are several therapies including WLL and augmentation therapy with GM-CSF available to treat PAP, but supporting evidence is still limited.

Pulmonary Alveolar Proteinosis and new therapeutic concepts

Pulmonary alveolar proteinosis (PAP) is an umbrella term used to refer to a pulmonary syndrome which is characterized by excessive accumulation of surfactant in the lungs of affected individuals. In general, PAP is a rare lung disease affecting children and adults, although its prevalence and incidence is variable among different countries. Even though PAP is a rare disease, it is a prime example on how modern medicine can lead to new therapeutic concepts, changing ways and techniques of (genetic) diagnosis which ultimately led into personalized treatments, all dedicated to improve the function of the impaired lung and thus life expectancy and quality of life in PAP patients. In fact, new technologies, such as new sequencing technologies, gene therapy approaches, new kind and sources of stem cells and completely new insights into the ontogeny of immune cells such as macrophages have increased our understanding in the onset and progression of PAP, which have paved the way for novel therapeutic concepts for PAP and beyond. As of today, classical monocyte-derived macrophages are known as important immune mediator and immune sentinels within the innate immunity. Furthermore, macrophages (known as tissue resident macrophages (TRMs)) can also be found in various tissues, introducing e. g. alveolar macrophages in the broncho-alveolar space as crucial cellular determinants in the onset of PAP and other lung disorders. Given recent insights into the onset of alveolar macrophages and knowledge about factors which impede their function, has led to the development of new therapies, which are applied in the context of PAP, with promising implications also for other diseases in which macrophages play an important role. Thus, we here summarize the latest insights into the various forms of PAP and introduce new pre-clinical work which is currently conducted in the framework of PAP, introducing new therapies for children and adults who still suffer from this severe, potentially life-threatening disease.

Recurrence of pulmonary alveolar proteinosis after bilateral lung transplantation in a patient with a nonsense mutation in CSF2RB

Hereditary pulmonary alveolar proteinosis (PAP) caused by mutations in CSF2RA or CSF2RB, which encode GM-CSF receptor α and β respectively, is a rare disease. Although some experimental therapeutic strategies have been proposed, no clinical evidence has yet been reported. We herein describe the clinical course and recurrence of hereditary PAP after lung transplantation. A 36-year-old woman developed PAP of unknown etiology. She underwent bilateral lung transplantation from living donors at the age of 42 years because of severe respiratory failure complicated by pulmonary fibrosis. However, PAP recurred after 9 months, and we found that donor-origin alveolar macrophages had been almost completely replaced with recipient-origin macrophages. We performed a genetic analysis and identified a point deletion in the CSF2RB gene that caused a GM-CSF receptor-mediated signaling defect. PAP progressed with fibrosis in both transplanted lungs, and the patient died of respiratory failure 5 years after the lung transplantation. Distinct from recent reports on pulmonary macrophage transplantation in mice, this case suggests that human alveolar macrophages might not maintain their population only by self-renewal but may depend on a supply of precursor cells from the circulation. Bone marrow transplantation should be considered for treatment of severe PAP with GM-CSF receptor gene deficiency.

Incidence and pattern of hemolytic anemia after minor ABO-mismatched living-donor lobar lung transplantation

PURPOSE

Living-donor lobar lung transplantation (LDLLT) has been successfully performed in Japan. In LDLLT, the recipient usually receives one lower lobe from each of two donors; however, finding two ABO-matched donors is often difficult. Solid organ transplants from donors with minor ABO-mismatches can be complicated by hemolysis. We investigated the incidence of de novo anti-ABO antibody production and hemolysis in patients receiving LDLLT across minor ABO-mismatches.

METHODS

We evaluated 23 patients who underwent LDLLT between June 2008 and December 2011, including 11 patients who underwent minor ABO-mismatched transplantation. We measured the anti-A/B antibody serum titers, hemoglobin concentrations and indirect bilirubin levels.

RESULTS

None of the patients showed any clinical signs of hemolytic anemia (mean follow-up period; 16 months). Two of the 11 patients (18 %) receiving minor ABO-mismatched LDLLTs showed a small amount of de novo anti-B antibodies for a transient period. These patients showed gradual progression of anemia, and weak de novo anti-A/B antibodies were detected with column agglutination technology. The patients received only 2 U of washed type O red blood cells; thereafter, the hemolytic anemia did not develop further in either case.

CONCLUSION

LDLLT across minor ABO-mismatches results in the transient appearance of weak de novo anti-A/B antibodies with a low incidence; thus, this procedure can be a safe treatment.