Hereditary pulmonary alveolar proteinosis: pathogenesis, presentation, diagnosis, and therapy

Whole-lung lavage for pediatric patients with pulmonary alveolar proteinosis

Pulmonary alveolar proteinosis (PAP) is a chronic disorder of surfactant clearance from the alveoli. Its prevalence is rare, especially in the pediatric population. Although there is no cure for this condition, symptoms of PAP are managed most effectively through whole-lung lavage (WLL). Perioperative RNs caring for children with PAP undergoing WLL in the OR should implement patient interventions to maintain vital signs and normothermia and preserve skin integrity. Additionally, perioperative RNs often are responsible for assembling closed-drainage systems for WLL. Detailed procedural preference cards, targeted education sessions, and multidisciplinary collaboration are crucial for establishing a comprehensive plan of care for the pediatric patient with PAP undergoing WLL in the OR.

An official American Thoracic Society clinical practice guideline: classification, evaluation, and management of childhood interstitial lung disease in infancy

BACKGROUND

There is growing recognition and understanding of the entities that cause interstitial lung disease (ILD) in infants. These entities are distinct from those that cause ILD in older children and adults.

METHODS

A multidisciplinary panel was convened to develop evidence-based guidelines on the classification, diagnosis, and management of ILD in children, focusing on neonates and infants under 2 years of age. Recommendations were formulated using a systematic approach. Outcomes considered important included the accuracy of the diagnostic evaluation, complications of delayed or incorrect diagnosis, psychosocial complications affecting the patient's or family's quality of life, and death.

RESULTS

No controlled clinical trials were identified. Therefore, observational evidence and clinical experience informed judgments. These guidelines: (1) describe the clinical characteristics of neonates and infants (<2 yr of age) with diffuse lung disease (DLD); (2) list the common causes of DLD that should be eliminated during the evaluation of neonates and infants with DLD; (3) recommend methods for further clinical investigation of the remaining infants, who are regarded as having "childhood ILD syndrome"; (4) describe a new pathologic classification scheme of DLD in infants; (5) outline supportive and continuing care; and (6) suggest areas for future research.

CONCLUSIONS

After common causes of DLD are excluded, neonates and infants with childhood ILD syndrome should be evaluated by a knowledgeable subspecialist. The evaluation may include echocardiography, controlled ventilation high-resolution computed tomography, infant pulmonary function testing, bronchoscopy with bronchoalveolar lavage, genetic testing, and/or lung biopsy. Preventive care, family education, and support are essential.

The parallel lives of alpha1-antitrypsin deficiency and pulmonary alveolar proteinosis

In 1963, five cases of alpha1-antitrypsin deficiency were reported in the scientific literature, as well as an attempt to treat pulmonary alveolar proteinosis by a massive washing of the lung (whole lung lavage). Now, fifty years later, it seems the ideal moment not only to commemorate these publications, but also to point out the influence both papers had in the following decades and how knowledge on these two fascinating rare respiratory disorders progressed over the years. This paper is therefore not aimed at being a comprehensive review for both disorders, but rather at comparing the evolution of alpha1-antitrypsin, a rare disorder, with that of pulmonary alveolar proteinosis, an ultra-rare disease. We wanted to emphasize how all stakeholders might contribute to the dissemination of the awareness of rare diseases, that need to be chaperoned from the ghetto of neglected disorders to the dignity of recognizable and treatable disorders.

De novo complex X chromosome rearrangement unmasking maternally inherited CSF2RA deletion in a girl with pulmonary alveolar proteinosis

We report on a 3-year-old girl with a de novo complex X chromosome rearrangement associated with congenital pulmonary alveolar proteinosis (PAP) and short stature. Array comparative genome hybridization and FISH analyses contributed to characterize the complex rearrangement consisting of a 7.37 Mb terminal deletion of Xp22.33p22.2, a 17.3 Mb interstitial inverted duplication of Xp22.2p21.3, and a 10.14 Mb duplication of Xq27.3q28. PCR analysis of microsatellite markers supported a paternal origin of the X chromosome rearrangement. A pre-meiotic two-step mechanism may explain the occurrence of this complex X rearrangement: an inverted duplication deletion event on Xp, and duplication of the Xq27.3qter region through a telomere capture event stabilizing the broken chromosome Xp end. The girl has also inherited from her healthy mother an X chromosome with a colony stimulating factor 2 receptor, alpha (CSF2RA) gene deletion. Consistent with the recessive mode of inheritance, the de novo paternal Xp22.33p22.2 deletion combined to the maternally inherited CSF2RA gene deletion led to homozygous deletion of CSF2RA and PAP diagnosis in the girl. The Xp deletion encompasses the pseudoautosomal region 1 (PAR1) which contains genes that escape X inactivation. Short stature homeobox (SHOX) haploinsufficiency explains growth retardation. Absence of other symptoms in relation to the X deletion/amplification is most probably due to skewed X inactivation. Finally, inherited deletions may unmask rare pathogenic genomic rearrangement and contribute to clinical phenotypes by a recessive mode of gene action.

Assessment and management of pulmonary alveolar proteinosis in a reference center

Pulmonary alveolar proteinosis (PAP) is a term defining an ultra-rare group of disorders characterised by a perturbation in surfactant homeostasis, resulting in its accumulation within airspaces and impaired gas transfer. In this report we provide data from a cohort of PAP patients (n=81) followed for more than two decades at the San Matteo University Hospital of Pavia, Italy. In agreement with other large series in PAP individuals, 90% of the study subjects were affected by autoimmune/idiopathic PAP, while the remaining subjects were divided as follow: congenital 1%, secondary 4% and PAP-like 5%. The disease affected males and females with a ratio of 2:1 and approximately one third of PAP patients were lifelong nonsmokers. Occupational exposure was reported in 35% of subjects in this series. With reference to the PAP clinical course, in 29 patients (7% with spontaneous remission) disease severity did not necessitate whole lung lavage (WLL) in the long-term follow up. On the other hand, 44 PAP patients underwent therapeutic WLL: in 31 subjects a single WLL was sufficient to provide long term, durable benefit, whereas 13 patients required multiple WLLs. The intra-patient mean interval between two consecutive WLLs was 15.7±13.6 months. When baseline data among never lavaged and PAP patients lavaged at least once were compared, the need for lavage was significantly associated with serum biomarkers (CEA, Cyfra, LDH), lung function parameters forced vital capacity (FVC), and lung diffusing capacity (Dlco). We conclude that patient cohorts with an ultra-rare disease, such as PAP, referred to a single reference center, can provide useful information on the natural history and clinical course of the disease.

The GM-CSF/IL-3/IL-5 cytokine receptor family: from ligand recognition to initiation of signaling

Granulocyte-macrophage colony-stimulating factor (GM-CSF), interleukin-3 (IL-3), and IL-5 are members of a discrete family of cytokines that regulates the growth, differentiation, migration and effector function activities of many hematopoietic cells and immunocytes. These cytokines are involved in normal responses to infectious agents, bridging innate and adaptive immunity. However, in certain cases, the overexpression of these cytokines or their receptors can lead to excessive or aberrant initiation of signaling resulting in pathological conditions, with chronic inflammatory diseases and myeloid leukemias the most notable examples. Recent crystal structures of the GM-CSF receptor ternary complex and the IL-5 binary complex have revealed new paradigms of cytokine receptor activation. Together with a wealth of associated structure-function studies, they have significantly enhanced our understanding of how these receptors recognize cytokines and initiate signals across cell membranes. Importantly, these structures provide opportunities for structure-based approaches for the discovery of novel and disease-specific therapeutics. In addition, recent biochemical evidence has suggested that the GM-CSF/IL-3/IL-5 receptor family is capable of interacting productively with other membrane proteins at the cell surface. Such interactions may afford additional or unique biological activities and might be harnessed for selective modulation of the function of these receptors in disease.

Hereditary pulmonary alveolar proteinosis. Could it be triggered by Mycoplasma pneumoniae pneumonia?

We present a three-year-old girl with respiratory failure due to hereditary pulmonary alveolar proteinosis caused by abnormal alpha chain of the granulocyte-macrophage colony-stimulating factor receptor. Both the patient and an asymptomatic seven-year-old sister were homozygous for the same mutation in CSF2RA. We speculate that the Mycoplasma pneumoniae pneumonia might have triggered the clinical presentation. While a good response to serial partial lung lavage was noticed, the ultimate outcome is uncertain.

The GM-CSF receptor family: mechanism of activation and implications for disease

Granulocyte-macrophage colony-stimulating factor (GM-CSF) is a pluripotent cytokine produced by many cells in the body, which regulates normal and malignant hemopoiesis as well as innate and adaptive immunity. GM-CSF assembles and activates its heterodimeric receptor complex on the surface of myeloid cells, initiating multiple signaling pathways that control key functions such as cell survival, cell proliferation, and functional activation. Understanding the molecular composition of these pathways, the interaction of the various components as well as the kinetics and dose-dependent mechanics of receptor activation provides valuable insights into the function of GM-CSF as well as the related cytokines, interleukin-3 and interleukin-5. This knowledge provides opportunities for the development of new therapies to block the action of these cytokines in hematological malignancy and chronic inflammation.

Genetic interstitial lung disease

The interstitial lung diseases (ILDs), or diffuse parenchymal lung diseases, are a heterogeneous collection of more than 100 different pulmonary disorders that affect the tissue and spaces surrounding the alveoli. Patients affected by ILD usually present with shortness of breath or cough; for many, there is evidence of pulmonary restriction, decreased diffusion capacity, and radiographic appearance of alveolar and/or reticulonodular infiltrates. This article reviews the inherited ILDs, with a focus on the diseases that may be seen by pulmonologists caring for adult patients. The authors conclude by briefly discussing the utility of genetic testing in this population.

Surfactant dysfunction

Mutations in genes encoding proteins needed for normal surfactant function and metabolism cause acute lung disease in newborns and chronic lung disease in older children and adults. While rare these disorders are associated with considerable pulmonary morbidity and mortality. The identification of genes responsible for surfactant dysfunction provides clues for candidate genes contributing to more common respiratory conditions, including neonatal respiratory distress syndrome and lung diseases associated with aging or environmental insults. While clinical, imaging and histopathology features of these disorders overlap, certain features are distinctive for surfactant dysfunction. Natural histories differ depending upon the genes involved and a specific diagnosis is important to provide accurate information concerning prognosis and mode of inheritance. Diagnosis of surfactant dysfunction can be made by biopsy, but identification of the specific gene involved requires molecular genetic testing, which is non-invasive. Currently there are no effective medical treatments for surfactant dysfunction. Development of therapies is a priority for research, which may benefit patients with other lung diseases.

Long-term follow-up and treatment of congenital alveolar proteinosis

Background

Clinical presentation, diagnosis, management and outcome of molecularly defined congenital pulmonary alveolar proteinosis (PAP) due to mutations in the GM-CSF receptor are not well known.

Case presentation

A 2 1/2 years old girl was diagnosed as having alveolar proteinosis. Whole lung lavages were performed with a new catheter balloon technique, feasible in small sized airways. Because of some interstitial inflammation in the lung biopsy and to further improve the condition, empirical therapy with systemic steroids and azathioprin, and inhaled and subcutaneous GMCSF, were used. Based on clinical measures, total protein and lipid recovered by whole lung lavages, all these treatments were without benefit. Conversely, severe respiratory viral infections and an invasive aspergillosis with aspergilloma formation occurred. Recently the novel homozygous stop mutation p.Ser25X of the GMCSF receptor alpha chain was identified in the patient. This mutation leads to a lack of functional GMCSF receptor and a reduced response to GMCSF stimulation of CD11b expression of mononuclear cells of the patient. Subsequently a very intense treatment with monthly lavages was initiated, resulting for the first time in complete resolution of partial respiratory insufficiency and a significant improvement of the overall somato-psychosocial condition of the child.

Conclusions

The long term management from early childhood into young adolescence of severe alveolar proteinosis due to GMCSF receptor deficiency requires a dedicated specialized team to perform technically demanding whole lung lavages and cope with complications.

Interstitial lung disease in children

PURPOSE OF REVIEW

In this review, we discuss the recent advances in our understanding of the cause, pathogenesis, presentation, diagnosis, treatment, and prognosis of interstitial lung disease (ILD) in children.

RECENT FINDINGS

The classification of ILD syndromes in children greater than 2 years of age is based largely on adult classification schemes. In children less than 2 years of age, classification has been developed and evaluated pathologically. Entities can be categorized into developmental disorders, growth abnormalities, and surfactant dysfunction disorders based on pathologic findings. Two distinctive entities, neuroendocrine cell hyperplasia of infancy and pulmonary interstitial glycogenosis, present early in life with characteristic findings. These two disorders appear to have a favorable prognosis. Diagnosis of ILD syndromes is based on the summation of history and physical findings and both noninvasive and invasive studies. Newer approaches are being evaluated to decrease the need for lung biopsy.

SUMMARY

Children's interstitial lung diseases are rare diffuse lung diseases resulting from a variety of pathogenic processes that include genetic factors, association with systemic disease processes, and inflammatory or fibrotic responses to stimuli. There are unique causes and presentations seen in infancy. Diagnosis in these disorders is made by the summation of clinical, radiologic, and pathologic findings.

Therapy options in pulmonary alveolar proteinosis

Pulmonary alveolar proteinosis is a rare condition characterized by the accumulation of lipoproteinaceous material within the airspaces, resulting in impaired gas transfer, and clinical manifestations ranging from asymptomatic to severe respiratory failure. To the best of the authors' knowledge, there are only a few conditions whose natural history has been so dramatically changed by the influence of advances in basic science, clinical medicine, and translational research in therapeutic approaches. Whole-lung lavage is the current standard of care and it plays a critical role as a modifier factor of the natural history of proteinosis. That notwithstanding, the identification of autoantibodies neutralizing granulocyte-macrophage colony-stimulating factor in serum and lung of patients affected by the form of proteinosis previously referred to as idiopathic, has opened the way to novel therapeutic options, such as supplementation of exogenous granulocyte-macrophage colony-stimulating factor, or strategies aimed at reducing the levels of the autoantibodies. The aim of this paper is to provide an updated review of the current therapeutic approach to proteinosis.