Surfactant protein C gene (SFTPC) mutation-associated lung disease: high-resolution computed tomography (HRCT) findings and its relation to histological analysis

Similarities and differences of interstitial lung disease associated with pathogenic variants in SFTPC and ABCA3 in adults

BACKGROUND AND OBJECTIVE

Variants in surfactant genes SFTPC or ABCA3 are responsible for interstitial lung disease (ILD) in children and adults, with few studies in adults.

METHODS

We conducted a multicentre retrospective study of all consecutive adult patients diagnosed with ILD associated with variants in SFTPC or ABCA3 in the French rare pulmonary diseases network, OrphaLung. Variants and chest computed tomography (CT) features were centrally reviewed.

RESULTS

We included 36 patients (median age: 34 years, 20 males), 22 in the SFTPC group and 14 in the ABCA3 group. Clinical characteristics were similar between groups. Baseline median FVC was 59% ([52-72]) and DLco was 44% ([35-50]). An unclassifiable pattern of fibrosing ILD was the most frequent on chest CT, found in 85% of patients, however with a distinct phenotype with ground-glass opacities and/or cysts. Nonspecific interstitial pneumonia and usual interstitial pneumonia were the most common histological patterns in the ABCA3 group and in the SFTPC group, respectively. Annually, FVC and DLCO declined by 1.87% and 2.43% in the SFTPC group, respectively, and by 0.72% and 0.95% in the ABCA3 group, respectively (FVC, p = 0.014 and DLCO , p = 0.004 for comparison between groups). Median time to death or lung transplantation was 10 years in the SFTPC group and was not reached at the end of follow-up in the ABCA3 group.

CONCLUSION

SFTPC and ABCA3-associated ILD present with a distinct phenotype and prognosis. A radiologic pattern of fibrosing ILD with ground-glass opacities and/or cysts is frequently found in these rare conditions.

Combined Pulmonary Fibrosis and Emphysema: When Scylla and Charybdis Ally

Combined pulmonary fibrosis and emphysema (CPFE) is a recently recognized syndrome that, as its name indicates, involves the existence of both interstitial lung fibrosis and emphysema in one individual, and is often accompanied by pulmonary hypertension. This debilitating, progressive condition is most often encountered in males with an extensive smoking history, and is presented by dyspnea, preserved lung volumes, and contrastingly impaired gas exchange capacity. The diagnosis of the disease is based on computed tomography imaging, demonstrating the coexistence of emphysema and interstitial fibrosis in the lungs, which might be of various types and extents, in different areas of the lung and several relative positions to each other. CPFE bears high mortality and to date, specific and efficient treatment options do not exist. In this review, we will summarize current knowledge about the clinical attributes and manifestations of CPFE. Moreover, we will focus on pathophysiological and pathohistological lung phenomena and suspected etiological factors of this disease. Finally, since there is a paucity of preclinical research performed for this particular lung pathology, we will review existing animal studies and provide suggestions for the development of additional in vivo models of CPFE syndrome.

Inherited pulmonary surfactant metabolism disorders in Argentina: Differences between patients with SFTPC and ABCA3 variants

BACKGROUND

Patients with inherited pulmonary surfactant metabolism disorders have a wide range of clinical outcomes and imaging findings. Response to current anti-inflammatory therapies has been variable and efficacy is unclear.

OBJECTIVE

To describe and compare genetic, clinical, histological, and computed tomography (CT) outcomes in a cohort of patients with variants in the genes encoding surfactant protein C (SP-C) or adenosine triphosphate-binding cassette transporter A3 (ABCA3) in Argentina.

METHODS

Observational cohort retrospective study. Patients carrying variants in genes encoding SP-C and ABCA3 proteins were included.

RESULTS

Fourteen patients met the inclusion criteria: SFTPC n = 6, ABCA3 n = 8 (seven were heterozygous and one compound heterozygous). Neonatal respiratory distress was more frequent and severe in neonates with variants in the ABCA3 gene. The onset of the disease occurred in infancy before the age of 20 months in all cases. Patients with ABCA3 pathogenic variants had a severe clinical course, while long-term outcomes were more favorable in individuals with SFTPC variants. Initial CT findings were ground glass opacities and intraparenchymal cysts in both groups. Over time, signs of lung fibrosis were present in 57% of patients with ABCA3 variants and in 33% of the SFTPC group. The efficacy of anti-inflammatory interventions appears to be poor, especially for patients with ABCA3 pathogenic variants.

CONCLUSIONS

Clinical, histological, and radiological features are similar in patients with SFTPC and ABCA3 variants; however, the latter have more severe clinical course. Current anti-inflammatory regimens do not appear to stop the progression of the disease.

Allogeneic Mesenchymal Stromal Cells as a Global Pediatric Prospective Approach in the Treatment of Respiratory Failure Associated with Surfactant Protein C Dysfunction

Mesenchymal stromal cells (MSCs) have been proposed as a new therapeutic strategy to treat congenital and acquired respiratory system diseases. We describe a case report of an 18-month-old male patient with progressive chronic respiratory failure, associated with mutations of the surfactant protein C gene (SFTPC) due to c.289G > T variant p.Gly97Ser (rs927644577) and c.176A > G variant (p.His59Arg), submitted to repeated intravenous infusions of allogeneic bone marrow (BM) MSCs. The clinical condition of the patient was monitored. Immunologic studies before and during MSC treatment were performed. No adverse events related to the MSC infusions were recorded. Throughout the MSC treatment period, the patient showed a growth recovery. Starting the second infusion, the patient experienced an improvement in his respiratory condition, with progressive adaptation to mechanical ventilation. After the third infusion, five hours/die of spontaneous breathing was shown, and after infusion IV, spontaneous ventilation for 24/24 h was recorded. A gradual decrease of lymphocytes and cell subpopulations was observed. No variations in the in vitro T cell response to PHA were determined by MSC treatment as well as for the in vitro B cell response. A decrease in IFN-γ, TNF-α, and IL-10 levels was also detected. Even though we cannot exclude an improvement of pulmonary function due to the physiological maturation, the well-known action of MSCs in the repair of lung tissue, together with the sequence of events observed in our patient, may support the therapeutic role of MSCs in this clinical condition. However, further investigations are necessary to confirm the result and long-term follow-up will be mandatory to confirm the benefits on the pulmonary condition.

Childhood interstitial lung disease more prevalent in infancy: a practical review

Childhood interstitial lung disease (chILD) is a heterogeneous group of uncommon, mostly chronic pediatric pulmonary disorders characterized by impaired gas exchange and diffuse abnormalities on imaging. A subset of these diseases occurs more frequently in infants and young children than in older children and teenagers. Some of these disorders occur in certain clinical scenarios and/or have typical imaging features that can help the radiologist recognize when to suggest a possible diagnosis and potentially spare a child a lung biopsy. We review the clinical, histopathological and computed tomography features of chILD more prevalent in infancy, including diffuse developmental disorders, growth abnormalities, specific conditions of undefined etiology, and surfactant dysfunction mutations and related disorders, to familiarize the pediatric radiologist with this group of disorders.

Childhood Interstitial Lung Disease: Imaging Guidelines and Recommendations

Childhood interstitial lung disease (ChILD) is an umbrella term encompassing a diverse group of diffuse lung diseases affecting infants and children. Although the timely and accurate diagnosis of ChILD is often challenging, it is optimally achieved through the multidisciplinary integration of imaging findings with clinical data, genetics, and potentially lung biopsy. This article reviews the definition and classification of ChILD; the role of imaging, pathology, and genetics in ChILD diagnosis; treatment options; and future goals. In addition, a practical approach to ChILD imaging based on the latest available research and the characteristic imaging appearance of ChILD entities are presented.

Surfactant Protein C Deficiency in a Puerto Rican Adolescent With a Rare SFTPC Genetic Variant

Surfactant protein C (SP-C) is a hydrophobic lipoprotein necessary for lowering alveolar surface tension and lung defense mechanisms. Defects in its function due to genetic mutations in the SFTPC gene have been increasingly identified in patients presenting with childhood interstitial lung disease. SFTPC mutations are inherited in an autosomal dominant pattern with reduced penetration and variable expressivity, although de novo mutations have also been documented. In this article, we present the case of an oxygen-dependent 13-year-old male with interstitial lung disease and severe pulmonary hypertension. Genetic analysis and lung biopsy confirmed the diagnosis of SP-C deficiency with the rare heterozygous mutation IVS4+2. To our knowledge, this is the first documented case of SP-C deficiency in the Puerto Rican population and the second worldwide with the IVS4+2 genetic mutation.

Ground glass and fibrotic change in children with surfactant protein C dysfunction mutations

INTRODUCTION

Therapeutics exist to treat fibrotic lung disease in adults, but these have not been investigated in children. Defining biomarkers for pediatric fibrotic lung disease in children is crucial for clinical trials. Children with surfactant protein C (SFTPC) dysfunction mutations develop fibrotic lung disease over time. We evaluated chest computed tomography (CT) changes over time in children with SFTPC dysfunction mutations.

METHODS

We performed an institutional review board-approved retrospective review of children with SFTPC dysfunction mutations. We collected demographic and clinical information. Chest CT scans were evaluated using visual and computerized scores. Chest CT scores and pulmonary function tests were reviewed.

RESULTS

Eleven children were included. All children presented in infancy and four children suffered from respiratory failure requiring mechanical ventilation. Those who performed pulmonary function tests had stable forced vital capacities over time by percent predicted, but increased forced vital capacity in liters. CT findings evolved over time in most patients with earlier CT scans demonstrating ground glass opacities and later CT scans with more fibrotic features. In a pilot analysis, data-driven textural analysis software identified fibrotic features in children with SFTPC dysfunction that increased over time and correlated with visual CT scores.

DISCUSSION

We describe 11 children with SFTPC dysfunction mutations. Increases in forced vital capacity over time suggest that these children experience lung growth and that therapeutic intervention may maximize lung growth. Ground glass opacities are the primary early imaging findings while fibrotic features dominate later. CT findings suggest the development of and increases in fibrotic features that may serve as potential biomarkers for antifibrotic therapeutic trials.

Impact of genetic factors on fibrosing interstitial lung diseases. Incidence and clinical presentation in adults

At least 10% of patients with pulmonary fibrosis, whether idiopathic or secondary, present heritable pulmonary fibrosis suspected on familial aggregation of pulmonary fibrosis, specific syndromes or early age of diagnosis. Approximately 30% of those patients have an identified mutation mostly in telomere related genes (TRG) more rarely in surfactant homeostasis or other genes. TRG mutation may be associated with hematological and hepatic diseases that may worsen after lung transplantation requiring a specific care and adapted immunosuppression. Surfactant genes mutations are usually associated with ground-glass opacities and cysts on CT scan and may improve with steroids, hydroxychloroquine or azithromycin. Moreover relatives should benefit from a genetic analysis associated with a clinical evaluation according to the gene involved. Genetics of pulmonary fibrosis raise specific problems from diagnosis, therapy or genetic counseling varying from one gene to another.

Alveolar Dynamics and Beyond - The Importance of Surfactant Protein C and Cholesterol in Lung Homeostasis and Fibrosis

Surfactant protein C (SP-C) is an important player in enhancing the interfacial adsorption of lung surfactant lipid films to the alveolar air-liquid interface. Doing so, surface tension drops down enough to stabilize alveoli and the lung, reducing the work of breathing. In addition, it has been shown that SP-C counteracts the deleterious effect of high amounts of cholesterol in the surfactant lipid films. On its side, cholesterol is a well-known modulator of the biophysical properties of biological membranes and it has been proven that it activates the inflammasome pathways in the lung. Even though the molecular mechanism is not known, there are evidences suggesting that these two molecules may interplay with each other in order to keep the proper function of the lung. This review focuses in the role of SP-C and cholesterol in the development of lung fibrosis and the potential pathways in which impairment of both molecules leads to aberrant lung repair, and therefore impaired alveolar dynamics. From molecular to cellular mechanisms to evidences in animal models and human diseases. The evidences revised here highlight a potential SP-C/cholesterol axis as target for the treatment of lung fibrosis.

An SFTPC gene mutation causes childhood interstitial lung disease: first report in the Arab region

Background

Surfactant protein C dysfunction is one of the causes of childhood interstitial lung disease but has not previously been reported in Arabian countries.

Case presentation

A six-year-old girl had presented at the age of eight months old with bronchiolitis followed by a persistent cough, dyspnea and hypoxaemia. She was found to have gastroesophageal reflux disease, but her symptoms did not resolve despite her therapy being optimised. Further tests, including a chest computed tomographic scan, lung biopsy and genetic testing, confirmed a diagnosis of surfactant protein C dysfunction.

Conclusion

We report the first case in the Arab region of childhood interstitial lung disease caused by surfactant protein C deficiency.

Correlation of BRCA2 gene mutation and prognosis as well as variant genes in invasive urothelial carcinoma of the bladder

BACKGROUND

This study aimed to investigate the correlation of BRCA2 gene mutation and prognosis as well as variant genes in patients with invasive urothelial carcinoma of the bladder. It predicted and explored the possible mechanism and clinical value of BRCA2 in the occurrence and development of tumors.

METHODS

Data sets of patients with bladder cancer were collected from the Cancer Genome Atlas (TCGA) database. Also the gene expression profile data and clinical information of the BRCA2 mutation group and non-BRCA2 mutation group were downloaded.

RESULTS

The prognosis of the BRCA2 mutation group was better than that of the non-mutant group. Among the down-regulated genes, the following genes showed significant differences between the two groups: CCL22, CYP2B6, CYP2E1, CYP4F2, HTR1E, HTR1F, KLRC1, NAPSA, SELL, SFTPA1, SFTPA2, SFTPB, SFTPC and STRA8, while the following genes among the up-regulated genes showed significant differences between the two groups: ELAVL3, NOTUM, TRH and VIP. Meanwhile, the following gene sets were highly enriched in BRCA2: cell cycle, DNA replication, homologous recombination, oocyte meiosis, ubiquitin-mediated proteolysis, base excision repair, progestin mediated oocyte maturation, basal transcription factor, biosynthesis of N polysaccharide, mismatch repair, sliceosome, purine metabolism as well as P53 and neurotrophic factor signaling pathway, etc.CONCLUSION: These findings suggested that the BRCA2 gene mutation is a good prognostic factor and can be used as a gene to predict the prognosis in the bladder cancer patients.

The genetics of interstitial lung diseases

Interstitial lung diseases (ILDs) are a set of heterogeneous lung diseases characterised by inflammation and, in some cases, fibrosis. These lung conditions lead to dyspnoea, cough, abnormalities in gas exchange, restrictive physiology (characterised by decreased lung volumes), hypoxaemia and, if progressive, respiratory failure. In some cases, ILDs can be caused by systemic diseases or environmental exposures. The ability to treat or cure these ILDs varies based on the subtype and in many cases lung transplantation remains the only curative therapy. There is a growing body of evidence that both common and rare genetic variants contribute to the development and clinical manifestation of many of the ILDs. Here, we review the current understanding of genetic risk and ILD.

Common and rare genetic variants contribute to the development and clinical manifestation of many interstitial lung diseaseshttp://bit.ly/31loHLh

Identification of genomic alterations in nasopharyngeal carcinoma and nasopharyngeal carcinoma-derived Epstein-Barr virus by whole-genome sequencing

Nasopharyngeal carcinoma (NPC) is a common tumor in southern China with marked ethnic and geographic distributions and concomitant Epstein-Barr virus (EBV) infection. However, the molecular basis of NPC remains largely unknown, and the role of EBV genomic variations in the pathogenesis of NPC is unclear. Whole-genome sequencing of a collection of 12 EBV-positive paired NPC tumor/peripheral blood samples from Hunan Province was performed, and the FBXO11 gene was subjected to further functional analyses. We identified 69 missense mutations in signaling pathways typically altered in cancer, including NF-κB and Wnt/Hedgehog/Notch. Additionally, 122 variations were identified in non-coding regions. Among these, a subset of genes was confirmed as dysregulated in NPC by mining the NPC cDNA microarray database. The randomly selected gene, FBXO11, could promote the malignant progression of NPC in vitro. Full-length EBV genomes from 8 of the 12 patients with NPC were also successfully assembled, and latent EBV infection is a primary cause of NPC. The various subtypes of EBV detected exhibited clear correlations with its geographical distribution. This study has explored novel biological markers and tumorigenic pathways with substantial potential to enhance therapeutic strategies for NPC.

Systematic review of drug effects in humans and models with surfactant-processing disease

Fibrotic interstitial pneumonias are a group of rare diseases characterised by distortion of lung interstitium. Patients with mutations in surfactant-processing genes, such as surfactant protein C (SFTPC), surfactant protein A1 and A2 (SFTPA1 and A2), ATP binding cassette A3 (ABCA3) and Hermansky-Pudlak syndrome (HPS1, 2 and 4), develop progressive pulmonary fibrosis, often culminating in fatal respiratory insufficiency. Although many mutations have been described, little is known about the optimal treatment strategy for fibrotic interstitial pneumonia patients with surfactant-processing mutations.We performed a systematic literature review of studies that described a drug effect in patients, cell or mouse models with a surfactant-processing mutation. In total, 73 articles were selected, consisting of 55 interstitial lung disease case reports/series, two clinical trials and 16 cell or mouse studies. Clinical effect parameters included lung function, radiological characteristics and clinical symptoms, while experimental outcome parameters included chemokine/cytokine expression, surfactant trafficking, necrosis and apoptosis. SP600125, a c-jun N-terminal kinase (JNK) inhibitor, hydroxychloroquine and 4-phenylbutyric acid were most frequently studied in disease models and lead to variable outcomes, suggesting that outcome is mutation dependent.This systematic review summarises effect parameters for future studies on surfactant-processing disorders in disease models and provides directions for future trials in affected patients.

Hermansky-Pudlak syndrome type 2 manifests with fibrosing lung disease early in childhood

Background

Hermansky-Pudlak syndrome (HPS), a hereditary multisystem disorder with oculocutaneous albinism, may be caused by mutations in one of at least 10 separate genes. The HPS-2 subtype is distinguished by the presence of neutropenia and knowledge of its pulmonary phenotype in children is scarce.

Methods

Six children with genetically proven HPS-2 presented to the chILD-EU register between 2009 and 2017; the data were collected systematically and imaging studies were scored blinded.

Results

Pulmonary symptoms including dyspnea, coughing, need for oxygen, and clubbing started 3.3 years before the diagnosis was made at the mean age of 8.83 years (range 2-15). All children had recurrent pulmonary infections, 3 had a spontaneous pneumothorax, and 4 developed scoliosis. The frequency of pulmonary complaints increased over time. The leading radiographic pattern was ground-glass opacities with a rapid increase in reticular pattern and traction bronchiectasis between initial and follow-up Computer tomography (CT) in all subjects. Honeycombing and cysts were newly detectable in 3 patients. Half of the patients received a lung biopsy for diagnosis; histological patterns were cellular non-specific interstitial pneumonia, usual interstitial pneumonia-like, and desquamative interstitial pneumonia.

Conclusions

HPS-2 is characterized by a rapidly fibrosing lung disease during early childhood. Effective treatments are required.

Electronic supplementary material

The online version of this article (10.1186/s13023-018-0780-z) contains supplementary material, which is available to authorized users.

Interstitial Lung Disease in Children Made Easier…Well, Almost

Interstitial lung disease (ILD) in pediatric patients is different from that in adults, with a vast array of pathologic conditions unique to childhood, varied modes of presentation, and a different range of radiologic appearances. Although rare, childhood ILD (chILD) is associated with significant morbidity and mortality, most notably in conditions of disordered surfactant function, with respiratory failure in 100% of neonates with surfactant protein B dysfunction and 100% mortality without lung transplantation. The authors present a summary of lung development and anatomy, followed by an organized approach, using the structure and nomenclature of the 2013 update to the chILD Research Network classification system, to aid radiologic diagnosis of chILD. Index radiologic cases with contemporaneous histopathologic findings illustrate a summary of recent imaging studies covering the full spectrum of chILD. chILD is best grouped by age at presentation from infancy (diffuse developmental disorders, lung growth abnormalities, specific conditions of unknown origin, surfactant dysfunction mutations) to later childhood (disorders of the normal host, disorders related to systemic disease processes, disorders related to immunocompromise). Appreciation of the temporal division of chILD into infant and later childhood onset, along with a sound understanding of pulmonary organogenesis and surfactant homeostasis, will aid in providing useful insight into this important group of pediatric conditions. Application of secondary lobular anatomy to interpretation of thin-section computed tomographic images is pivotal to understanding patterns of ILD and will aid in selecting and narrowing a differential diagnosis. ^©RSNA, 2017.

Pulmonary Neuroendocrine Cell Hyperplasia Associated with Surfactant Protein C Gene Mutation

Familial interstitial lung disease (ILD) is defined as presence of ILD in 2 or more family members. Surfactant protein C (SFTPC) gene mutations are rare, but well-known cause of familial ILD. We reported a 20-year-old male, who was referred for lung transplantation. He was symptomatic at age 3 and underwent surgical lung biopsy at age 6, which revealed a nonspecific interstitial pneumonia (NSIP) pattern. Genetic workup revealed a novel SFTPC mutation in the first intron with a C to A transversion. At age 21, he underwent bilateral lung transplantation. Explanted lung histology suggested NSIP. In addition there was pulmonary neuroendocrine cell (PNEC) hyperplasia and carcinoid tumorlets. His mother had undergone lung transplantation several years earlier, and her explanted lung showed similar pathology. SFTPC mutations are inherited in an autosomal dominant pattern. Various types of ILD have been associated with SFTPC mutation including NSIP, usual interstitial pneumonia (UIP), and desquamative interstitial pneumonia (DIP). PNEC hyperplasia has been described to occur in association with lung inflammation but has not been previously described with familial ILD associated with SFTPC mutation.

Management of suspected monogenic lung fibrosis in a specialised centre

At least 10% of patients with interstitial lung disease present monogenic lung fibrosis suspected on familial aggregation of pulmonary fibrosis, specific syndromes or early age of diagnosis. Approximately 25% of families have an identified mutation in genes mostly involved in telomere homeostasis, and more rarely in surfactant homeostasis.

Beyond pathophysiological knowledge, detection of these mutations has practical consequence for patients. For instance, mutations involved in telomere homeostasis are associated with haematological complications after lung transplantation and may require adapted immunosuppression. Moreover, relatives may benefit from a clinical and genetic evaluation that should be specifically managed.

The field of genetics of pulmonary fibrosis has made great progress in the last 10 years, raising specific problems that should be addressed by a specialised team.

Genetic disorders of surfactant protein dysfunction: when to consider and how to investigate

Genetic mutations affecting proteins required for normal surfactant protein function are a rare cause of respiratory disease. The genes identified that cause respiratory disease are surfactant protein B, surfactant protein C, ATP binding cassette number A3 and thyroid transcription factor-1. Surfactant protein dysfunction syndromes are highly variable in their onset and presentation, and are dependent on the genes involved and environmental factors. This heterogeneous group of conditions can be associated with significant morbidity and mortality. Presentation may be in a full-term neonate with acute and progressive respiratory distress with a high mortality or later in childhood or adulthood with signs and symptoms of interstitial lung disease. Genetic testing for these disorders is now available, providing a non-invasive diagnostic test. Other useful investigations include radiological imaging and lung biopsy. This review will provide an overview of the genetic and clinical features of surfactant protein dysfunction syndromes, and discuss when to suspect this diagnosis, how to investigate it and current treatment options.

Targeted Disruption of Ig-Hepta/Gpr116 Causes Emphysema-like Symptoms That Are Associated with Alveolar Macrophage Activation

Ig-Hepta/GPR116 is a member of the G protein-coupled receptor family predominantly expressed in the alveolar type II epithelial cells of the lung. Previous studies have shown that Ig-Hepta is essential for lung surfactant homeostasis, and loss of its function results in high accumulation of surfactant lipids and proteins in the alveolar space. Ig-Hepta knock-out (Ig-Hepta(-/-)) mice also exhibit emphysema-like symptoms, including accumulation of foamy alveolar macrophages (AMs), but its pathogenic mechanism is unknown. Here, we show that the bronchoalveolar lavage fluid obtained from Ig-Hepta(-/-) mice contains high levels of inflammatory mediators, lipid hydroperoxides, and matrix metalloproteinases (MMPs), which are produced by AMs. Accumulation of reactive oxygen species was observed in the AMs of Ig-Hepta(-/-) mice in an age-dependent manner. In addition, nuclear factor-κB (NF-κB) is activated and translocated into the nuclei of the AMs of Ig-Hepta(-/-) mice. Release of MMP-2 and MMP-9 from the AMs was strongly inhibited by treatment with inhibitors of oxidants and NF-κB. We also found that the level of monocyte chemotactic protein-1 is increased in the embryonic lungs of Ig-Hepta(-/-) mice at 18.5 days postcoitum, when AMs are not accumulated and activated. These results suggest that Ig-Hepta plays an important role in regulating macrophage immune responses, and its deficiency leads to local inflammation in the lung, where AMs produce excessive amounts of reactive oxygen species and up-regulate MMPs through the NF-κB signaling pathway.

Genotype alone does not predict the clinical course ofSFTPCdeficiency in paediatric patients

Patients with interstitial lung disease due to surfactant protein C (SFTPC) mutations are rare and not well characterised.

We report on all subjects collected over a 15-year period in the kids-lung register with interstitial lung disease and a provenSFTPCmutation. We analysed clinical courses, interventions and outcomes, as well as histopathological and radiological interrelations.

17 patients (seven male) were followed over a median of 3 years (range 0.3–19). All patients were heterozygous carriers of autosomal dominantSFTPCmutations. Three mutations (p.L101P, p.E191 K and p.E191*) have not been described before in the context of surfactant protein C deficiency. Patients with alterations in the BRICHOS domain of the protein (amino acids 94–197) presented earlier. At follow-up, one patient was healthy (2 years), six patients were “sick-better” (2.8 years, range 0.8–19), seven patients were “sick-same” (6.5 years, 1.3–15.8) and three patients were “sick-worse” (0.3 years, 0.3–16.9). Radiological findings changed from ground-glass to increasing signs of fibrosis and cyst formation with increasing age. Empiric treatments had variable effects, also in patients with the same genotype.

Prospective studies with randomised interventions are urgently needed and can best be performed in the framework of international registers.

Familial pulmonary fibrosis

The occurrence of pulmonary fibrosis in numerous individuals from the same family suggests a genetic cause for the disease. During the last 10 years, mutations involving proteins from the telomerase complex and from the surfactant system have been identified in association with pulmonary fibrosis. Mutations of TERT, the coding gene for the telomerase reverse transcriptase, are the most frequently identified mutations and are present in 15% of cases of familial pulmonary fibrosis. Other mutations (TERC, surfactant proteins genes) are only rarely evidenced in adults. Patients with mutations involving the telomerase complex may present with pulmonary fibrosis, hematologic, cutaneous or liver diseases. Other genetic variations associated with pulmonary fibrosis such as a polymorphism in the promoter of MUC5B or a polymorphism in TERT have been recently described, and could be considered to be part of a polygenic transmission. Evidence for mutations associated with the development of pulmonary fibrosis raises numerous clinical questions from establishing a diagnosis, providing counselling to deciding on therapy, and requires specific studies. From a pathophysiological point of view, the function of the genes highlights the central role of alveolar epithelium and aging in fibrogenesis.

Diagnostic criteria and follow-up in neuroendocrine cell hyperplasia of infancy: a case series

OBJECTIVE

Neuroendocrine cell hyperplasia of infancy (NEHI) is a form of childhood interstitial lung disease characterized by tachypnea, retractions, crackles, and hypoxia. The aim of this study was to report and discuss the clinical, imaging, and histopathological findings in a series of NEHI cases at a tertiary pediatric hospital, with an emphasis on diagnostic criteria and clinical outcomes.

METHODS

Between 2003 and 2011, 12 full-term infants were diagnosed with NEHI, based on clinical and tomographic findings. Those infants were followed for 1-91 months. Four infants were biopsied, and the histopathological specimens were stained with bombesin antibody.

RESULTS

In this case series, symptoms appeared at birth in 6 infants and by 3 months of age in the remaining 6. In all of the cases, NEHI was associated with acute respiratory infection. The most common initial chest HRCT findings were ground-glass opacities that were in the middle lobe/lingula in 12 patients and in other medullary areas in 10. Air trapping was the second most common finding, being observed in 7 patients. Follow-up HRCT scans (performed in 10 patients) revealed normal results in 1 patient and improvement in 9. The biopsy findings were nonspecific, and the staining was positive for bombesin in all samples. Confirmation of NEHI was primarily based on clinical and tomographic findings. Symptoms improved during the follow-up period (mean, 41 months). A clinical cure was achieved in 4 patients.

CONCLUSIONS

In this sample of patients, the diagnosis of NEHI was made on the basis of the clinical and tomographic findings, independent of the lung biopsy results. Most of the patients showed clinical improvement and persistent tomographic changes during the follow-up period, regardless of the initial severity of the disease or type of treatment.

Primary pulmonary alveolar proteinosis: computed tomography features at diagnosis

BACKGROUND

Pulmonary alveolar proteinosis (PAP) is characterized by an abnormal accumulation of periodic acid-schiff-positive lipoproteinaceous material in the alveoli. Early diagnosis allows setting up of therapeutic lung lavages, which reduces the need for oxygen supplementation and weight gain.

OBJECTIVE

To provide a description of radiological features by CT at the onset of primary PAP in children.

MATERIALS AND METHODS

The clinical and radiological data of 24 patients, including 16 boys and 8 girls (median age: 12 months), diagnosed with a primary form of PAP between April 1992 and May 2012 in a tertiary referral hospital, were retrospectively reviewed. CT images were examined for the presence of alveolar and interstitial elementary lesions. Correlation between clinical and radiological findings was assessed.

RESULTS

The types of elementary lesions detected were: ground-glass opacities (n = 24), intralobular lines (n = 24), thickened interlobular septa (n = 22), thickened fissures (n = 21), airspace consolidation (n = 16), hyperinflation (n = 16), cystic lesions (n = 2) and micronodules (n = 1). A crazy-paving pattern was found in 92% of cases. Consolidation and hyperinflation were especially detected in younger children (median age, 8 months, P < 0.01). A density dependent gradient was found. The distribution of the lesions was symmetrical. There was no correlation between radiological and clinical data of severity of the disease.

CONCLUSION

CT findings are suggestive of diagnosis of PAP in immunocompetent children with chronic respiratory failure.

Diffuse Lung Disease

Diffuse lung disease (DLD) comprises a diverse group of disorders characterized by widespread pulmonary parenchymal pathology and impaired gas exchange. While many of these disorders are categorized under the rubric of interstitial lung disease (ILD), some of these disorders involve the airspaces or peripheral airways in addition to, or rather than, the interstitium. Some of these disorders are present primarily in infancy or early childhood, while others that are prevalent in adulthood rarely occur in childhood. This chapter will review the classification of pediatric DLD and the characteristic imaging findings of specific disorders to facilitate accurate diagnosis and guide appropriate treatment of children with these disorders.

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.

[Lung diseases in children associated with inherited disorders of surfactant metabolism]

Pulmonary surfactant is a unique mixture of lipids and specific proteins that reduces surface tension at the air-liquid interface, preventing collapse of the lung at the end of expiration. Recessive loss-of-function mutations of pulmonary surfactant protein B (SP-B) was initially described in infants who develop respiratory failure at birth. More recently, mutations in other constitutive surfactant proteins like surfactant protein C or implied in its metabolism like ATP-binding cassette, sub-family A, member 3 (ABCA3) or NK2 homeobox (NKX2-1) were identified in newborn with respiratory distress but also in children with diffuse infiltrative pneumonia. Intra-alveolar accumulation of protein related to surfactant dysfunction leads to cough, hypoxemia and radiological abnormalities including ground-glass opacities and lung cysts. The clinical and radiological features associated with these genetic disorders, along with their treatment and outcome, are reviewed.

Combined pulmonary fibrosis and emphysema

The advent of computed tomography permitted recognition of the coexistence of pulmonary fibrosis and emphysema (CPFE). Emphysema is usually encountered in the upper lobes preceding fibrosis of the lower lobes, and patients are smokers, predominantly male, with distinct physiologic profile characterized by preserved lung volumes and markedly reduced diffusion capacity. Actually, the term CPFE is reserved for the coexistence of any type and grade of radiological pulmonary emphysema and the idiopathic usual interstitial pneumonia computed tomography pattern as well as any pathologically confirmed case. CPFE is complicated by pulmonary hypertension, lung cancer and acute lung injury and may present different outcome than that of its components.

Familial forms of nonspecific interstitial pneumonia/idiopathic pulmonary fibrosis: clinical course and genetic background

PURPOSE OF REVIEW

Familial pulmonary fibrosis has long been recognized and suggests that pulmonary fibrosis may have a genetic origin in some cases with an autosomal dominant transmission.

RECENT FINDINGS

Mutations in the telomerase complex and in the surfactant pathways have been discovered in the last decade. Almost 20% of the cases of familial pulmonary fibrosis are related to known functional mutations in one of these systems. A polymorphism in the promoter of the MUC5B gene has been associated with both sporadic and familial forms of idiopathic pulmonary fibrosis; however, the impact of this association remains to be determined.

SUMMARY

These genes point to alveolar epithelium injury and repair as a major component of the fibrotic process.

4-Phenylbutyric acid treatment rescues trafficking and processing of a mutant surfactant protein-C

Mutations in the SFTPC gene, encoding surfactant protein-C (SP-C), are associated with interstitial lung disease (ILD). Knowledge of the intracellular fate of mutant SP-C is essential in the design of therapies to correct trafficking/processing of the proprotein, and to prevent the formation of cytotoxic aggregates. We assessed the potential of a chemical chaperone to correct the trafficking and processing of three disease-associated mutant SP-C proteins. HEK293 cells were stably transfected with wild-type (SP-C(WT)) or mutant (SP-C(L188Q), SP-C(Δexon4), or SP-C(I73T)) SP-C, and cell lines with a similar expression of SP-C mRNA were identified. The effects of the chemical chaperone 4-phenylbutyric acid (PBA) and lysosomotropic drugs on intracellular trafficking to the endolysosomal pathway and the subsequent conversion of SP-C proprotein to mature peptide were assessed. Despite comparable SP-C mRNA expression, proprotein concentrations varied greatly: SP-C(I73T) was more abundant than SP-C(WT) and was localized to the cell surface, whereas SP-C(Δexon4) was barely detectable. In contrast, SP-C(L188Q) and SP-C(WT) proprotein concentrations were comparable, and a small amount of SP-C(L188Q) was localized to the endolysosomal pathway. PBA treatment restored the trafficking and processing of SP-C(L188Q) to SP-C(WT) concentrations, but did not correct the mistrafficking of SP-C(I73T) or rescue SP-C(Δexon4). PBA treatment also promoted the aggregation of SP-C proproteins, including SP-C(L188Q). This study provides proof of the principle that a chemical chaperone can correct the mistrafficking and processing of a disease-associated mutant SP-C proprotein.

[Genetic disorders of surfactant]

Lung diseases associated with surfactant metabolism disorders represent a significant but heterogeneous group of rare disorders. Intra-alveolar accumulation of protein related to surfactant dysfunction leads to cough, hypoxemia and radiological diffuse infiltration. Inherited deficiency of pulmonary surfactant protein B (SP-B) was initially described in term newborns who develop severe respiratory failure at birth. More recently, mutations in surfactant protein C (SP-C) or in proteins required for surfactant synthesis such as ATP-binding cassette, sub-family A, member 3 (ABCA3) or NK2 homeobox 1 (NKX2-1) were identified in newborns with respiratory distress but also in children with diffuse infiltrative pneumonia. The aim of this review is to describe the clinical presentation of these diseases but also the diagnostic tools and the treatments options available.

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.