Pulmonary alveolar proteinosis: progress in the first 44 years

Pathogenesis-driven treatment of primary pulmonary alveolar proteinosis

Pulmonary alveolar proteinosis (PAP) is a syndrome that results from the accumulation of lipoproteinaceous material in the alveolar space. According to the underlying pathogenetic mechanisms, three different forms have been identified, namely primary, secondary and congenital. Primary PAP is caused by disruption of granulocyte-macrophage colony-stimulating factor (GM-CSF) signalling due to the presence of neutralising autoantibodies (autoimmune PAP) or GM-CSF receptor genetic defects (hereditary PAP), which results in dysfunctional alveolar macrophages with reduced phagocytic clearance of particles, cholesterol and surfactant. The serum level of GM-CSF autoantibody is the only disease-specific biomarker of autoimmune PAP, although it does not correlate with disease severity. In PAP patients with normal serum GM-CSF autoantibody levels, elevated serum GM-CSF levels is highly suspicious for hereditary PAP. Several biomarkers have been correlated with disease severity, although they are not specific for PAP. These include lactate dehydrogenase, cytokeratin 19 fragment 21.1, carcinoembryonic antigen, neuron-specific enolase, surfactant proteins, Krebs von Lungen 6, chitinase-3-like protein 1 and monocyte chemotactic proteins. Finally, increased awareness of the disease mechanisms has led to the development of pathogenesis-based treatments, such as GM-CSF augmentation and cholesterol-targeting therapies.

A Comprehensive Outlook on Pulmonary Alveolar Proteinosis-A Review

Pulmonary alveolar proteinosis (PAP) is an ultra-rare disease caused by impaired pulmonary surfactant clearance due to the dysfunction of alveolar macrophages or their signaling pathways. PAP is categorized into autoimmune, congenital, and secondary PAP, with autoimmune PAP being the most prevalent. This article aims to present a comprehensive review of PAP classification, pathogenesis, clinical presentation, diagnostics, and treatment. The literature search was conducted using the PubMed database and a total of 67 articles were selected. The PAP diagnosis is usually based on clinical symptoms, radiological imaging, and bronchoalveolar lavage, with additional GM-CSF antibody tests. The gold standard for PAP treatment is whole-lung lavage. This review presents a summary of the most recent findings concerning pulmonary alveolar proteinosis, pointing out specific features that require further investigation.

Autoimmune Pulmonary Alveolar Proteinosis Complicated by Myelodysplastic Syndrome

Pulmonary alveolar proteinosis (PAP) is characterized by an abnormal surfactant accumulation in peripheral air spaces. Autoimmune PAP (APAP) results from macrophage dysfunction caused by anti-granulocyte-macrophage colony-stimulating factor (GM-CSF) autoantibodies, and the presence of antibodies more than the cutoff value is specific for APAP. In contrast, secondary PAP (SPAP) does not require anti-GM-CSF autoantibodies and is complicated by other diseases, including myelodysplastic syndrome (MDS). A 73-year-old man with anemia and thrombocytopenia was diagnosed with APAP and MDS simultaneously. The measurement of serum anti-GM-CSF autoantibodies is important for the correct diagnosis and management of PAP, even with an established diagnosis of underlying SPAP-suggestive disease.

Incidence, mortality, and disability-adjusted life years due to silicosis worldwide, 1990-2019: evidence from the global burden of disease study 2019

Silicosis is an occupational lung disease because of exposure to silica dust in the workplace. Evidence on the spatiotemporal change of silicosis burden worldwide remains limited. This study utilized data extracted from the Global Burden of Disease Study 2019 to examine the numbers and age-standardized rates of incidence (ASIR), mortality (ASMR), and disability-adjusted life years (DALYs) caused by silicosis between 1990 and 2019. Average annual percentage changes (AAPCs) were calculated to evaluate the temporal trends of age-standardized indicators by sex, region, and socio-demographic index (SDI) since 1990. Results indicated an increase in new silicosis cases globally, rising by 64.61% from 84,426 in 1990 to 138,971 in 2019, with a sustained high number of DALYs attributed to this disease. Although the global age-standardized rates of incidence, mortality, and DALYs of silicosis have decreased since 1990, the number of new cases has increased in 168 countries and territories, and the ASIR of silicosis has also risen in 118 countries and territories, primarily in developing countries. Since 1990, the burden of silicosis among the elderly has significantly increased. Countries with higher SDI experienced a more rapid decline in the silicosis burden. Silicosis remains a public health problem that requires significant attention. Programs for prevention and elimination of this public health issue need to be established in more countries and territories. Protecting young workers from silica dust exposure is crucial to prevent the onset of silicosis in their later years and to reduce the disease burden among older workers.

Systemic juvenile idiopathic arthritis-associated lung disease: A retrospective cohort study

BACKGROUND

Lung damage in systemic juvenile arthritis (sJIA) is one of the contemporary topics in pediatric rheumatology. Several previous studies showed the severe course and fatal outcomes in some patients. The information about interstitial lung disease (ILD) in the sJIA is scarce and limited to a total of 100 cases.

AIM

To describe the features of sJIA patients with ILD in detail.

METHODS

In the present retrospective cohort study, information about 5 patients less than 18-years-old with sJIA and ILD were included. The diagnosis of sJIA was made according to the current 2004 and new provisional International League of Associations for Rheumatology criteria 2019. ILD was diagnosed with chest computed tomography with the exclusion of other possible reasons for concurrent lung involvement. Macrophage activation syndrome (MAS) was diagnosed with HLH-2004 and 2016 EULAR/ACR/PRINTO Classification Criteria and hScores were calculated during the lung involvement.

RESULTS

The onset age of sJIA ranged from 1 year to 10 years. The time interval before ILD ranged from 1 mo to 3 years. The disease course was characterized by the prevalence of the systemic features above articular involvement, intensive rash (100%), persistent and very active MAS (hScore range: 194-220) with transaminitis (100%), and respiratory symptoms (100%). Only 3 patients (60%) developed a clubbing phenomenon. All patients (100%) had pleural effusion and 4 patients (80%) had pericardial effusion at the disease onset. Two patients (40%) developed pulmonary arterial hypertension. Infusion-related reactions to tocilizumab were observed in 3 (60%) of the patients. One patient with trisomy 21 had a fatal disease course. Half of the remaining patients had sJIA remission and 2 patients had improvement. Lung disease improved in 3 patients (75%), but 1 of them had initial deterioration of lung involvement. One patient who has not achieved the sJIA remission had the progressed course of ILD. No cases of hyper-eosinophilia were noted. Four patients (80%) received canakinumab and one (20%) tocilizumab at the last follow-up visit.

CONCLUSION

ILD is a severe life-threatening complication of sJIA that may affect children of different ages with different time intervals since the disease onset. Extensive rash, serositis (especially pleuritis), full-blown MAS with transaminitis, lymphopenia, trisomy 21, eosinophilia, and biologic infusion reaction are the main predictors of ILD. The following studies are needed to find the predictors, pathogenesis, and treatment options, for preventing and treating the ILD in sJIA patients.

Anti-cytokine autoantibodies: mechanistic insights and disease associations

Anti-cytokine autoantibodies (ACAAs) are increasingly recognized as modulating disease severity in infection, inflammation and autoimmunity. By reducing or augmenting cytokine signalling pathways or by altering the half-life of cytokines in the circulation, ACAAs can be either pathogenic or disease ameliorating. The origins of ACAAs remain unclear. Here, we focus on the most common ACAAs in the context of disease groups with similar characteristics. We review the emerging genetic and environmental factors that are thought to drive their production. We also describe how the profiling of ACAAs should be considered for the early diagnosis, active monitoring, treatment or sub-phenotyping of diseases. Finally, we discuss how understanding the biology of naturally occurring ACAAs can guide therapeutic strategies.

Human autoantibodies neutralizing type I IFNs: From 1981 to 2023

Human autoantibodies (auto-Abs) neutralizing type I IFNs were first discovered in a woman with disseminated shingles and were described by Ion Gresser from 1981 to 1984. They have since been found in patients with diverse conditions and are even used as a diagnostic criterion in patients with autoimmune polyendocrinopathy syndrome type 1 (APS-1). However, their apparent lack of association with viral diseases, including shingles, led to wide acceptance of the conclusion that they had no pathological consequences. This perception began to change in 2020, when they were found to underlie about 15% of cases of critical COVID-19 pneumonia. They have since been shown to underlie other severe viral diseases, including 5%, 20%, and 40% of cases of critical influenza pneumonia, critical MERS pneumonia, and West Nile virus encephalitis, respectively. They also seem to be associated with shingles in various settings. These auto-Abs are present in all age groups of the general population, but their frequency increases with age to reach at least 5% in the elderly. We estimate that at least 100 million people worldwide carry auto-Abs neutralizing type I IFNs. Here, we briefly review the history of the study of these auto-Abs, focusing particularly on their known causes and consequences.

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.

Ten-year experience of whole lung lavage in pediatric Pulmonary Alveolar Proteinosis

BACKGROUND

Pulmonary Alveolar Proteinosis (PAP) is extremely rare and can be caused by hereditary dysfunction of the granulocyte macrophage colony-stimulating factor receptor (GM-CSF) receptor, autoantibodies against GM-CSF, or other diseases leading to alveolar macrophage (AM) dysfunction. This leads to protein accumulation in the lung and severe dyspnea and hypoxemia. Whole lung lavage (WLL) is the first line treatment strategy.

METHODS

Here, we present data from more than ten years of WLL practice in pediatric PAP. WLL performed by the use of a single lumen or double lumen tube (SLT vs. DLT) were compared for technical features, procedure time, and adverse events.

RESULTS

A total of n=57 procedures in six PAP patients between 3.5 and 14.3 years of age were performed. SLT based WLL in smaller children was associated with comparable rates of adverse events but with longer intervention times and postprocedural intensive care treatment when compared to DLT based procedures.

DISCUSSION

Our data shows that WLL is feasible even in small children. DLT based WLL seems to be more effective, and our data supports the notion that it should be considered as early as possible in pediatric PAP.

CONCLUSION

WLL lavage is possible in small PAP patients but should performed in close interdisciplinary cooperation and with age appropriate protocols.

Infections in autoimmune pulmonary alveolar proteinosis: a large retrospective cohort

BACKGROUND

Autoimmune pulmonary alveolar proteinosis (aPAP) is a rare disease, predisposing to an increased risk of infection. A complete picture of these infections is lacking.

RESEARCH QUESTION

Describe the characteristics and clinical outcomes of patients diagnosed with aPAP, and to identify risk factors associated with opportunistic infections.

METHODS

We conducted a retrospective cohort including all patients diagnosed with aPAP between 2008 and 2018 in France and Belgium. Data were collected using a standardised questionnaire including demographics, comorbidities, imaging features, outcomes and microbiological data.

RESULTS

We included 104 patients, 2/3 were men and median age at diagnosis was 45 years. With a median follow-up of 3.4 years (IQR 1.7-6.6 years), 60 patients (58%), developed at least one infection, including 23 (22%) with opportunistic infections. Nocardia spp was the main pathogen identified (n=10). Thirty-five (34%) patients were hospitalised due to infection. In univariate analysis, male gender was associated with opportunistic infections (p=0.04, OR=3.88; 95% CI (1.02 to 22.06)). Anti-granulocyte macrophage colony-stimulating factor antibody titre at diagnosis was significantly higher among patients who developed nocardiosis (1058 (316-1591) vs 580 (200-1190), p=0.01). Nine patients had died (9%), but only one death was related to infection.

INTERPRETATION

Patients with aPAP often presented with opportunistic infections, especially nocardiosis, which highlights the importance of systematic search for slow-growing bacteria in bronchoalveolar lavage or whole lung lavage.

Pulmonary alveolar proteinosis in Taiwan

BACKGROUND/PURPOSE

Pulmonary alveolar proteinosis (PAP) is rare disease manifested as alveolar macrophage dysfunction and abnormal accumulation of surfactant protein in the alveoli. In this nationwide, population-based study, we investigated the epidemiology of PAP in Taiwan, and discovered the comorbidities and prognostic factors of PAP.

METHODS

From the National Health Insurance Research Database (NHIRD), we obtained comprehensive information about all patients of PAP in Taiwan between 1995 and 2013. The incidence, baseline characteristics comorbidities, and prognostic factors of PAP were investigated.

RESULTS

The annual incidence rate of PAP was around 0.79 (range: 0.49-1.17) patients per million people after 2000, and the prevalence rate was 7.96 patients per million people by the end of 2013. In total, 276 patients of PAP were identified, including 177 (64%) and 99 (36%) patients with primary and secondary PAP, respectively. The median age of diagnosis was 53.8 years. The median survival was 9.6 years after the initial PAP diagnosis, and the 5-year survival rate was 65.96%. Twenty (7%) patients received whole lung lavage (WLL) within three months after the diagnosis had significantly better survival compared to the others. Multivariable Cox regression analyses showed that elder age, secondary PAP, and malignancy were associated with poorer survival, while WLL within 3 months of diagnosis might greatly improve the survival.

CONCLUSION

We demonstrated the epidemiology of PAP in Taiwan, showing several poor prognostic factors and the potential effectiveness of WLL. Further prospective studies based on registry are warranted to improve the diagnosis and treatment of PAP.

Pulmonary Alveolar Proteinosis-associated Pulmonary Fibrosis: Evolutional Changes and Radiologic-Pathologic Correlation

Pulmonary alveolar proteinosis (PAP) is a rare disease with frequently favorable outcomes. In a minority of patients with primary or secondary PAP, the disease course may be complicated by pulmonary fibrosis (PF) despite appropriate management. Imaging and histopathologic manifestations of uncomplicated PAP are well-known. In contrast, radiologic-pathologic descriptions of PAP-associated PF (PAP-PF) are limited. The current manuscript presents three cases of PAP-PF, each with serial high-resolution CT imaging demonstrating the longitudinal progression of this unusual complication, with concordant pathologic findings in two patients. Much remains to be known regarding adverse prognostic factors contributing to PAP-PF. Early recognition of radiologic-pathologic manifestations would allow timely diagnosis and management optimization. Keywords: CT, Lung, Inflammation, Pathology © RSNA, 2023.

Autoimmune Pulmonary Alveolar Proteinosis That Improved after a COVID-19 Episode

Autoimmune pulmonary alveolar proteinosis (APAP) is caused by macrophage dysfunction owing to the presence of anti-granulocyte-macrophage colony-stimulating factor (GM-CSF) autoantibodies. A 77-year-old man with APAP was referred to our hospital for whole-lung lavage (WLL) due to oxygenation exacerbation and pulmonary shadows. The patient had had coronavirus disease 2019 (COVID-19) during the APAP evaluation before WLL. About three months after COVID-19 resolved, his oxygenation and shadow reflecting APAP had obviously improved, thus avoiding the need for WLL. We suspected that the improvement in APAP was due to various immunological reactions induced by COVID-19.

Alveolar macrophages in pulmonary alveolar proteinosis: origin, function, and therapeutic strategies

Pulmonary alveolar proteinosis (PAP) is a rare pulmonary disorder that is characterized by the abnormal accumulation of surfactant within the alveoli. Alveolar macrophages (AMs) have been identified as playing a pivotal role in the pathogenesis of PAP. In most of PAP cases, the disease is triggered by impaired cholesterol clearance in AMs that depend on granulocyte-macrophage colony-stimulating factor (GM-CSF), resulting in defective alveolar surfactant clearance and disruption of pulmonary homeostasis. Currently, novel pathogenesis-based therapies are being developed that target the GM-CSF signaling, cholesterol homeostasis, and immune modulation of AMs. In this review, we summarize the origin and functional role of AMs in PAP, as well as the latest therapeutic strategies aimed at addressing this disease. Our goal is to provide new perspectives and insights into the pathogenesis of PAP, and thereby identify promising new treatments for this disease.

Nationwide survey of adult patients with pulmonary alveolar proteinosis using the National Database of designated intractable diseases of Japan

BACKGROUND

Autoimmune pulmonary alveolar proteinosis (APAP) and congenital/hereditary PAP were labeled intractable diseases in Japan in 2015. Since then, patients registered in the National Database of Designated Incurable Diseases (NDDID) who met certain requirements became eligible for medical subsidies. Epidemiological studies using recent data are needed for the development of management protocols for patients with PAP.

METHODS

We conducted the first nationwide study describing the epidemiology and characteristics of PAP using data for patients registered in the Japanese NDDID between 2015 and 2020. We focused on patient demographics, diagnosis, disease severity score (DSS), symptoms, test results, and treatment.

RESULTS

We identified 110 patients with PAP, among whom 96.4% had APAP/idiopathic PAP (IPAP). The median age was 58 years, with a slight male predominance. Most patients had a DSS ≥3 (64.5%) and reported symptoms (e.g., dyspnea on exertion). High-resolution computed tomography typically revealed ground glass opacity and crazy paving appearances. Pulmonary function was relatively preserved, except for carbon monoxide diffusing capacity. Only 27.4% of patients underwent therapeutic whole-lung lavage and/or bronchoalveolar lavage, while 25% required long-term oxygen therapy. Serum Krebs von den Lungen-6, surfactant protein D, and lactate dehydrogenase levels significantly and positively correlated with the DSS.

CONCLUSIONS

Most patients registered in the NDDID have APAP/IPAP with a DSS ≥3, and about one-quarter require long-term oxygen therapy and infrequent lavages. Our results provide important details of the current prevalence and clinical practice related to APAP/IPAP with a DSS ≥3 in Japan.

Granulocyte-macrophage colony-stimulating factor: Conductor of the wound healing orchestra?

Granulocyte-macrophage colony-stimulating factor (GM-CSF) is a glycoprotein and is derived from both hemopoietic and nonhemopoietic sources which exert immunomodulatory properties. Various theories have been proposed to explain why some wounds become chronic and non-healing. Generalized suppression of inflammation locally or systemically may impede the body's physiological healing response by crippling the activity of reparative cells within the wound ecosystem. Thus, highlighting the importance of promoting host-directed therapeutics with immunomodulatory properties. The temporal and spatial expression of GM-CSF and GM-CSF receptors in the integumentary system suggests that epithelial-derived GM-CSF functions in an autocrine/paracrine manner. This may positively affect wound healing physiology via local inflammatory regulation promoting macrophage survival. Although diabetes negatively affects multiple aspects of wound healing GM-CSF activation is particularly impacted. Compared to acute/healthy wounds diabetic foot ulcers (DFU) only partially activate GM-CSF activity. There is a deleterious chain of events associated with this unfortunate sequala. DFUs also have a high proportion of monocytes and an absence of activated macrophages which results in an impaired inflammatory response. This may potentially serve as a vital point for GM-CSF to act as a companion diagnostic/theragnostic modality to help modulate the inflammatory response in wound healing. Correcting macrophage immune dysfunction with exogenous GM-CSF may help restore the immune balance in the wound ecosystem and jumpstart the wound healing cascade. Thus, the recognized beneficial role of GM-CSF in immune regulation across many studies provides a rationale for the initiation of the ongoing randomized controlled trials using GM-CSF.

Surfactant Protein A Can Affect Macrophage Phagocytosis: An Important Pathogenic Mechanism of Otitis Media with Effusion

Otitis media with effusion (OME), also known as secretory otitis media, is a common condition in otorhinolaryngology. The main manifestations include middle ear effusion and conductive hearing loss. Recently, increasing attention has been paid to the etiology of OME, wherein immune dysfunction is one important pathogenic mechanism. However, it is unknown whether changes in surfactant protein A (SPA) secretion affect the phagocytic activity of macrophages in the Eustachian tube, thereby altering pathogen clearance, during the pathogenesis of OME. In our study, an OME animal model was established and evaluated. Differences in SPA levels in Eustachian tube lavage fluid between the experimental and control groups were analyzed. Cell-based experiments revealed that SPA decreased the expression of CD64 and SYK and inhibited phagocytosis by RAW264.7 cells. By using flow cytometry and immunofluorescence, we confirmed that macrophage phagocytosis decreased with increasing SPA levels. Finally, we concluded that SPA affects macrophage function and plays a role in the occurrence and development of OME.

The world of rare interstitial lung diseases

The world of rare interstitial lung diseases (ILDs) is diverse and complex. Diagnosis and therapy usually pose challenges. This review describes a selection of rare and ultrarare ILDs including pulmonary alveolar proteinosis, pulmonary alveolar microlithiasis and pleuroparenchymal fibroelastosis. In addition, monogenic ILDs or ILDs in congenital syndromes and various multiple cystic lung diseases will be discussed. All these conditions are part of the scope of the European Reference Network on rare respiratory diseases (ERN-LUNG). Epidemiology, pathogenesis, diagnostics and treatment of each disease are presented.

Updated severity and prognosis score of pulmonary alveolar proteinosis: A multi-center cohort study in China

Background

The high-resolution computed tomography (HRCT) score is an important component of the severity and prognosis score of pulmonary alveolar proteinosis (SPSP). However, the HRCT score in SPSP only considers the extent of opacity, which is insufficient.

Methods

We retrospectively evaluated HRCT scores for 231 patients with autoimmune pulmonary alveolar proteinosis (APAP) from three centers of the China Alliance for Rare Diseases. The SPSPII was created based on the overall density and extent, incorporating the SPSP. The severity of APAP patients was assessed using disease severity scores (DSS), SPSP, and SPSPII to determine the strengths and weaknesses of the different assessment methods. We then prospectively applied the SPSPII to patients before treatment, and the curative effect was assessed after 3 months.

Results

The HRCT overall density and extent scores in our retrospective analysis were higher than the extent scores in all patients and every original extent score severity group, as well as higher related to arterial partial oxygen pressure (PaO₂) than extent scores. The mild patients accounted for 61.9% based on DSS 1-2, 20.3% based on SPSP 1-3, and 20.8% based on SPSPII 1-3. Based on SPSP or SPSPII, the number of severe patients deteriorating was higher in the mild and moderate groups. When applied prospectively, arterial PaO₂ differed between any two SPSPII severity groups. The alveolar-arterial gradient in PaO₂ (P[A-a]O₂), % predicted carbon monoxide diffusing capacity of the lung (DLCO), and HRCT score were higher in the severe group than in the mild and moderate groups. After diagnosis, mild patients received symptomatic treatment, moderate patients received pure whole lung lavage (WLL) or granulocyte-macrophage colony-stimulating factor (GM-CSF) therapy, and severe patients received WLL and GM-CSF therapy. Importantly, the SPSPII in mild and severe groups were lower than baseline after 3 months.

Conclusion

The HRCT density and extent scores of patients with APAP were better than the extent score. The SPSPII score system based on smoking status, symptoms, PaO₂, predicted DLCO, and overall HRCT score was better than DSS and SPSP for assessing the severity and efficacy and predicting the prognosis.

Trial registration

ClinicalTrial.gov, identifier: NCT04516577.

Recombinant GM-CSF for diseases of GM-CSF insufficiency: Correcting dysfunctional mononuclear phagocyte disorders

Introduction

Endogenous granulocyte-macrophage colony-stimulating factor (GM-CSF), identified by its ability to support differentiation of hematopoietic cells into several types of myeloid cells, is now known to support maturation and maintain the metabolic capacity of mononuclear phagocytes including monocytes, macrophages, and dendritic cells. These cells sense and attack potential pathogens, present antigens to adaptive immune cells, and recruit other immune cells. Recombinant human (rhu) GM-CSF (e.g., sargramostim [glycosylated, yeast-derived rhu GM-CSF]) has immune modulating properties and can restore the normal function of mononuclear phagocytes rendered dysfunctional by deficient or insufficient endogenous GM-CSF.

Methods

We reviewed the emerging biologic and cellular effects of GM-CSF. Experts in clinical disease areas caused by deficient or insufficient endogenous GM-CSF examined the role of GM-CSF in mononuclear phagocyte disorders including autoimmune pulmonary alveolar proteinosis (aPAP), diverse infections (including COVID-19), wound healing, and anti-cancer immune checkpoint inhibitor therapy.

Results

We discuss emerging data for GM-CSF biology including the positive effects on mitochondrial function and cell metabolism, augmentation of phagocytosis and efferocytosis, and immune cell modulation. We further address how giving exogenous rhu GM-CSF may control or treat mononuclear phagocyte dysfunction disorders caused or exacerbated by GM-CSF deficiency or insufficiency. We discuss how rhu GM-CSF may augment the anti-cancer effects of immune checkpoint inhibitor immunotherapy as well as ameliorate immune-related adverse events.

Discussion

We identify research gaps, opportunities, and the concept that rhu GM-CSF, by supporting and restoring the metabolic capacity and function of mononuclear phagocytes, can have significant therapeutic effects. rhu GM-CSF (e.g., sargramostim) might ameliorate multiple diseases of GM-CSF deficiency or insufficiency and address a high unmet medical need.

Alveolar Proteinosis in COVID-19: Clinical Case

Pulmonary alveolar proteinosis (PAP) is a rare, diffuse lung disease characterized by accumulation of lipoprotein in lung surfactant in the alveolar space and terminal bronchioles, leading to impaired gas exchange and arterial hypoxemia. We present the case of a 51-year-old woman who was admitted with a diagnosis of severe SARS-CoV-2 pneumonia. Her condition did not improve with corticosteroids. A chest CT scan revealed ground-glass opacities in all lung lobes, with septal thickening. A differential diagnosis was proposed with other diseases. Bronchoscopy revealed milky bronchoalveolar lavage fluid, and staining with periodic acid-Schiff was positive, thus indicating PAP. Therefore, the patient underwent whole lung lavage, which led to clinical, radiological, and functional improvement. In the context of the COVID-19 pandemic, differential diagnosis ensures that appropriate attention is given to less prevalent entities such as PAP.

Unilateral Autoimmune Pulmonary Alveolar Proteinosis with Polymyositis-related Interstitial Lung Disease

A 61-year-old patient with cystic bronchiectasis and bronchial artery hyperplasia in the left lung was diagnosed with polymyositis-related interstitial lung disease. After nine months of immunosuppressive therapy, he developed unilateral autoimmune pulmonary alveolar proteinosis (APAP) in the right lung with respiratory failure. After bronchial artery embolization to prevent massive hemoptysis, whole-lung lavage was performed using veno-venous extracorporeal membrane oxygenation. His respiratory condition improved, and he was discharged from the hospital with supplemental oxygen. Three reported cases of APAP with polymyositis-related interstitial lung disease, including the present case, were all positive for anti-glycyl tRNA synthetase antibody and were under immunosuppressive treatment.

Characteristics of hospital admissions for pulmonary alveolar proteinosis: analysis of the nationwide inpatient sample (2012-2014)

BACKGROUND

Pulmonary alveolar proteinosis (PAP) is a rare clinical syndrome involving the accumulation of lipid-rich proteinaceous material in the alveoli. There is a paucity of published studies on this condition. To better characterize the demographics, complication rates, mortality, and healthcare costs of patients hospitalized for PAP in the United States, a secondary analysis on the Hospital Cost and Utilization Project's Nationwide Inpatient Sample (NIS) was performed on patients admitted from 2012 to 2014 with a diagnosis of pulmonary alveolar proteinosis.

METHODS

Using the NIS database, a secondary analysis was performed on 500 admissions with the diagnosis "pulmonary alveolar proteinosis." The clinical variables and outcome measures extracted were: patient demographics, hospital costs, length of stay, frequency of admissions, and inpatient mortality rate.

RESULTS

Among a weighted estimate of 500 hospital admissions from 2012 to 2014, the number of PAP admissions averaged 4.7 per million. The population was predominantly male (55%) with a mean age of 41.45 (CI 38.3-44.5) from all socioeconomic levels. Inpatient mortality was calculated to be 5%, which may result from the fact that the majority of admitted patients had few or no comorbid conditions (CCI 0.72). The most common procedure performed during admission was a bronchoalveolar lavage. Mean length of stay was 6.2 days (CI 3.9-8.5) and average cost of admission was $29,932.20 (CI 13,739-46,124). Of note, 50% of these admissions were considered "elective."

CONCLUSIONS

Demographics of patients with PAP who have been hospitalized in the United States are similar to previously reported demographics from prior patient cohorts, specifically a male predominance and a mean age in the 40 s. The inpatient mortality rate of 5% we found is consistent with prior studies demonstrating good disease-specific survival rates. Notably, the cost per admission and overall annual cost associated with PAP hospitalization was calculated to be $29932.20 and $5 million respectively. This reflects the high economic cost associated with hospitalization of PAP patients, and provokes thought about ways to make treatment more cost-effective.

GM-CSF antibodies in artificial stone associated silicoproteinosis: A case report and literature review

Pulmonary alveolar proteinosis (PAP) is a rare lung disease where there is accumulation of surfactant in the alveoli. It can be classified based on the underlying aetiology into three categories: primary, secondary and congenital. Autoantibodies to granulocyte-macrophage colony-stimulating factor (GM-CSF-Ab) are a key diagnostic feature of autoimmune PAP. High intensity occupational exposure and inhalation of toxic particles such as silica can cause a form of secondary PAP called acute silicoproteinosis. We describe a 26-year-old stone benchtop fabricator with silicoproteinosis following daily exposure to high levels of silica who had elevated serum GM-CSF-Ab. We discuss the role of GM-CSF-Ab in cases of PAP with occupational inhalational exposure and the challenges in its interpretation.

Pulmonary Alveolar Proteinosis and Pregnancy: A Review of the Literature and Case Presentation

Pulmonary Alveolar Proteinosis (PAP) is a rare, usually autoimmune, disease, where surfactant accumulates within alveoli due to decreased clearance, causing dyspnea and hypoxemia. The disease is even more rare in pregnancy; nevertheless, it has been reported in pregnant women and can even appear for the first time during pregnancy as an asthma-like illness. Therefore, awareness is important. Similarly to many autoimmune diseases, it can worsen during pregnancy and postpartum, causing maternal and fetal/neonatal complications. This paper offers a narrative literature review of PAP and pregnancy, while illustrating a case of a pregnant patient with known PAP who developed preeclampsia in the third trimester but had an overall fortunate maternal and neonatal outcome.

Complete remission of pulmonary alveolar proteinosis after anti-tuberculous chemotherapy: a case report

Pulmonary alveolar proteinosis (PAP) is a rare respiratory system disorder. Patients with PAP are at risk for a wide variety of secondary infections. This current case report describes a patient with PAP complicated by tuberculosis. A 48-year-old male patient with multiple follow-up chest computed tomography scans that showed predominant diffuse ground glass opacity in both lung fields, presented a few years later with new calcified lesions and pleural effusion. At this point, the associated auxiliary examination indicated the possibility of PAP combined with tuberculosis infection. The patient achieved complete remission after anti-tuberculosis treatment. PAP is an easily overlooked clinical syndrome due to its low prevalence and lack of specific clinical manifestations, especially when combined with other pulmonary lesions. Therefore, clinicians should consider this rare disease in patients presenting with pulmonary disease and plan for its co-morbidity with other secondary outcomes, such as opportunistic infections, which are a common and life-threatening complication in patients with PAP. This case indicates the possibility that anti-tuberculosis therapy can improve alveolar proteinosis in patients with PAP and secondary Mycobacterium tuberculosis infection.

Correction of a chronic pulmonary disease through lentiviral vector-mediated protein expression

We developed a novel lentiviral vector, pseudotyped with the F and HN proteins from Sendai virus (rSIV.F/HN), that produces long-lasting, high-efficiency transduction of the respiratory epithelium. Here we addressed whether this platform technology can secrete sufficient levels of a therapeutic protein into the lungs to ameliorate a fatal pulmonary disease as an example of its translational capability. Pulmonary alveolar proteinosis (PAP) results from alveolar granulocyte-macrophage colony-stimulating factor (GM-CSF) insufficiency, resulting in abnormal surfactant homeostasis and consequent ventilatory problems. Lungs of GM-CSF knockout mice were transduced with a single dose of rSIV.F/HN-expressing murine GM-CSF (mGM-CSF; 1e5-92e7 transduction units [TU]/mouse); mGM-CSF expression was dose related and persisted for at least 11 months. PAP disease biomarkers were rapidly and persistently corrected, but we noted a narrow toxicity/efficacy window. rSIV.F/HN may be a useful platform technology to deliver therapeutic proteins for lung diseases requiring long-lasting and stable expression of secreted proteins.

A case of autoimmune pulmonary alveolar proteinosis with severe respiratory failure treated with segmental lung lavage and oral statin therapy

Pulmonary alveolar proteinosis (PAP) is a diffuse lung disease characterized by the accumulation of alveolar surfactants due to dysfunction of granulocyte-macrophage colony-stimulating factor-dependent cholesterol clearance. Whole-lung lavage is the current standard of care for PAP, but it can lead to the exacerbation of hypoxia. A medication targeting cholesterol homeostasis is a promising therapy for refractory PAP. We present a case of autoimmune PAP with severe hypoxia that was successfully treated with segmental lung lavage (SLL). Following SLL for disease relapse, statin treatment for dyslipidemia was started. After initiating statin treatment, the patient did not require bronchoalveolar lavage for 10 months.

Single lung transplantation for idiopathic pulmonary alveolar proteinosis with intraoperative veno-venous extracorporeal membrane oxygenation support

Pulmonary alveolar proteinosis (PAP) is a rarely progressive disease. This disease is characterized by the accumulation of a large amount of pulmonary surfactant in the alveolar cavity and terminal bronchiole, which is caused by the obstruction of clearance due to the weakened function of alveolar macrophages in vivo. Idiopathic PAP(IPAP) is the most common type of PAP, accounting for about 90%, and its pathogenesis remains unclear. The treatments of PAP include whole lung lavage, inhaled/subcutaneous GM-CSF, rituximab, plasmapheresis and lung transplantation. We describe a patient with IPAP who is in good condition five years after undergoing a single lung transplantation(SLT). This is the first report of IPAP treated with SLT. Accourding to the previous report and the follow-up result, lung transplantation may be an effective long-term treatment for both secondary PAP and IPAP.

Autoimmune Pulmonary Alveolar Proteinosis

Autoimmune pulmonary alveolar proteinosis (PAP) is a rare disease characterized by myeloid cell dysfunction, abnormal pulmonary surfactant accumulation, and innate immune deficiency. It has a prevalence of 7-10 per million; occurs in individuals of all races, geographic regions, sex, and socioeconomic status; and accounts for 90% of all patients with PAP syndrome. The most common presentation is dyspnea of insidious onset with or without cough, production of scant white and frothy sputum, and diffuse radiographic infiltrates in a previously healthy adult, but it can also occur in children as young as 3 years. Digital clubbing, fever, and hemoptysis are not typical, and the latter two indicate that intercurrent infection may be present. Low prevalence and nonspecific clinical, radiological, and laboratory findings commonly lead to misdiagnosis as pneumonia and substantially delay an accurate diagnosis. The clinical course, although variable, usually includes progressive hypoxemic respiratory insufficiency and, in some patients, secondary infections, pulmonary fibrosis, respiratory failure, and death. Two decades of research have raised autoimmune PAP from obscurity to a paradigm of molecular pathogenesis-based diagnostic and therapeutic development. Pathogenesis is driven by GM-CSF (granulocyte/macrophage colony-stimulating factor) autoantibodies, which are present at high concentrations in blood and tissues and form the basis of an accurate, commercially available diagnostic blood test with sensitivity and specificity of 100%. Although whole-lung lavage remains the first-line therapy, inhaled GM-CSF is a promising pharmacotherapeutic approach demonstrated in well-controlled trials to be safe, well tolerated, and efficacious. Research has established GM-CSF as a pulmonary regulatory molecule critical to surfactant homeostasis, alveolar stability, lung function, and host defense.

Efficacy and safety of whole-lung lavage for pulmonary alveolar proteinosis: a protocol for a systematic review and meta-analysis

INTRODUCTION

Pulmonary alveolar proteinosis (PAP) is an ultrarare disorder characterised by the accumulation of alveolar surfactant and the dysfunction of alveolar macrophages that results in hypoxemic respiratory failure. Whole-lung lavage (WLL) is currently the primary therapy for PAP. However, systematic evaluation of the clinical efficacy of WLL is lacking. We aim to perform a systematic review and meta-analysis of existing evidence to support WLL for the clinical treatment of PAP.

METHODS AND ANALYSIS

We will search the PubMed (MEDLINE), Cochrane Library, Embase, Web of Science and Google Scholar databases from inception to December 2021 for observational studies using WLL for the treatment of PAP. Two authors will independently screen the eligible studies, assess the quality of the included papers and extract the required information. Review Manager V.5.4 will be used to perform the meta-analysis. We will evaluate the overall quality of evidence using the Grading of Recommendations, Assessment, Development and Evaluation approach. All steps of this protocol will be performed using the Cochrane Handbook for Preferred Reporting Items for Systematic Review and Meta-analysis statement.

ETHICS AND DISSEMINATION

This systematic review and meta-analysis will be based on published data. Therefore, ethical approval is not required. We will publish our results in a peer-reviewed journal.

PROSPERO REGISTRATION NUMBER

CRD42022306221 (https://www.crd.york.ac.uk/prospero/display_record.php?ID=CRD42022306221).

Opportunistic Infection Associated with Elevated GM-CSF Autoantibodies: A Case Series and Review of the Literature

Granulocyte-macrophage colony-stimulating factor (GM-CSF) is known to play a key role in enhancing multiple immune functions that affect response to infectious pathogens including antigen presentation, complement- and antibody-mediated phagocytosis, microbicidal activity, and neutrophil chemotaxis. Reduced GM-CSF activity and immune response provides a mechanism for increased infection risk associated with autoimmune pulmonary alveolar proteinosis (aPAP) and other disorders involving the presence of GM-CSF autoantibodies. We present a case series of five patients with persistent or unusual pulmonary and central nervous system opportunistic infections (Cryptococcus gattii, Flavobacterium, Nocardia) and elevated GM-CSF autoantibody levels, as well as 27 cases identified on systematic review of the literature.

Human autoantibodies underlying infectious diseases

The vast interindividual clinical variability observed in any microbial infection-ranging from silent infection to lethal disease-is increasingly being explained by human genetic and immunological determinants. Autoantibodies neutralizing specific cytokines underlie the same infectious diseases as inborn errors of the corresponding cytokine or response pathway. Autoantibodies against type I IFNs underlie COVID-19 pneumonia and adverse reactions to the live attenuated yellow fever virus vaccine. Autoantibodies against type II IFN underlie severe disease caused by environmental or tuberculous mycobacteria, and other intra-macrophagic microbes. Autoantibodies against IL-17A/F and IL-6 are less common and underlie mucocutaneous candidiasis and staphylococcal diseases, respectively. Inborn errors of and autoantibodies against GM-CSF underlie pulmonary alveolar proteinosis; associated infections are less well characterized. In individual patients, autoantibodies against cytokines preexist infection with the pathogen concerned and underlie the infectious disease. Human antibody-driven autoimmunity can interfere with cytokines that are essential for protective immunity to specific infectious agents but that are otherwise redundant, thereby underlying specific infectious diseases.

Autoimmune pulmonary alveolar proteinosis exacerbated by steroid therapy due to misdiagnosis as anti-aminoacyl-tRNA synthetase (ARS) antibody positive- interstitial pneumonia: a case report

BACKGROUND

Anti-aminoacyl-tRNA synthetase (anti-ARS) antibodies are myositis-specific autoantibodies that have been identified in a subset of patients with interstitial pneumonia who do not present with dermatomyositis or polymyositis. Anti-ARS antibody-positive interstitial pneumonia is commonly treated with steroids or immunosuppressive agents and is usually responsive to these therapies. Here, we present in detail a case in which respiratory failure of a patient diagnosed with anti-ARS antibody-positive interstitial pneumonia was exacerbated by treatment with steroids and immunosuppressive agents. Further examination revealed misdiagnosis of this patient and a subsequent diagnosis of autoimmune pulmonary alveolar proteinosis.

CASE PRESENTATION

A 66-year-old man presented to the hospital with dyspnea on exertion, which resulted in the detection of interstitial pneumonia. Serum anti-ARS antibodies were detected; however, there were no other findings suggestive of myositis. Pulmonary alveolar proteinosis (PAP) was suspected based on the marked increase in serum KL-6 and chest computed tomography findings. The bronchoalveolar lavage revealed no milky changes in the lavage fluid. After treatment with steroids and initiation of immunosuppressive agents for anti-ARS antibody-positive interstitial pneumonia, respiratory failure and chest imaging findings showed worsening of the condition. Bronchoscopy was repeated, and milk-like alveolar lavage fluid was collected; serum anti-granulocyte macrophage colony-stimulating factor antibody was identified. Steroids and immunosuppressive agents were gradually tapered and discontinued, and the patient's condition stabilized after repeated alveolar lavage under general anesthesia.

CONCLUSION

Due to similar presentation, PAP can be misdiagnosed as interstitial pneumonia. If pulmonary lesions due to interstitial pneumonia are exacerbated by immunosuppressive treatment, physicians should reconsider the diagnosis and include PAP in the differential diagnosis.

A Bibliometric Analysis of Pulmonary Alveolar Proteinosis From 2001 to 2021

Background

Pulmonary alveolar proteinosis (PAP) is a rare syndrome first described by Rosen et al. in 1958. Despite our considerably evolved understanding of PAP over the past decades, no bibliometric studies have been reported on this field. We aimed to analyze and visualize the research hotspots and current trends of the PAP research field using a bibliometric analysis to help understand the future development of basic and clinical research.

Methods

The literature regarding PAP was culled from the Web of Science Core Collection (WoSCC) database. Data were extracted from the relevant articles and visually analyzed using CiteSpace and VOSviewer software.

Results

Nine hundred and nine qualifying articles were included in the analysis. Publications regarding PAP increased over time. These articles mainly come from 407 institutions of 57 countries. The leading countries were the USA and Japan. University of Cincinnati (USA) and Niigata University (Japan) featured the highest number of publications among all institutions. Bruce C Trapnell exerts a significant publication impact and has made the most outstanding contributions in the field of PAP. American Journal of Physiology-Lung Cellular and Molecular Physiology was the journal with the most publications, and American Journal of Respiratory and Critical Care Medicine was the most commonly cited journal. All the top 5 co-cited journals belong to Q1. Keyword citation bursts revealed that inflammation, deficiency, tissue resident macrophage, classification, autoimmune pulmonary alveolar proteinosis, sarcoidosis, gm csf, high resolution ct, and fetal monocyte were the emerging research hotspots.

Conclusion

Research on PAP is prosperous. International cooperation is also expected to deepen and strengthen in the future. Our results indicated that the etiology and pathogenesis of PAP, current and emerging therapies, especially the novel pathogenesis-based options will remain research hotspots in the future.

A mini-whole lung lavage to treat autoimmune pulmonary alveolar proteinosis (PAP)

Background

PAP is an ultra-rare respiratory syndrome characterized by the accumulation of surfactant within the alveoli. Whole lung lavage (WLL) is the current standard of care of PAP, however it is not a standardized procedure and the total amount of fluid used to wash each lung is still debated. Considering ICU hospitalization associated risks, a “mini-WLL” with anticipated manual clapping and reduced total infusion volume and has been proposed in our center.

The aim of the study is to retrospectively analyze the efficacy of mini-WLL compared to standard WLL at the Pavia center.

Methods

13 autoimmune PAP patients eligible for WLL were included: 7 patients were admitted to mini-WLL (9 L total infusion volume for each lung) and 6 patients underwent standard WLL (14 L of infusion volume). Functional data (VC%, FVC%, TLC%, DLCO%) and alveolar-arterial gradient values (A-aO2) were collected at the baseline and 1, 3, 6, 12, 18 months after the procedure.

Results

A statistically significant improvement of VC% (p = 0.013, 95%CI 3.49–30.19), FVC% (p = 0.016, 95%CI 3.37–32.09), TLC% (p = 0.001, 95%CI 7.38–30.34) was observed in the mini-WLL group in comparison with the standard WLL group, while no significant difference in DLCO% and A-aO2 mean values were reported.

Conclusion

Mini-WLL has demonstrated higher efficacy in ameliorating lung volumes, suggesting that a lower infusion volume is sufficient to remove the surfactant accumulation and possibly allows a reduced mechanical insult of the bronchi walls and the alveoli. However, no statistically significant differences were found in terms of DLCO% and Aa-O2.

Sirolimus-Induced Pulmonary Alveolar Proteinosis in the Context of Hematopoietic Stem Cells Transplant Rejection: A Case Report

Pulmonary alveolar proteinosis (PAP) is a rare parenchymal pulmonary disease, characterized by the accumulation of surfactant material in alveoli. Rare cases of pulmonary alveolar proteinosis have been reported following the use of sirolimus. All published cases have been described following solid organ transplantation, and symptoms improved quickly after treatment's cessation. We describe a case of PAP secondary to sirolimus treating graft-versus-host reaction in a patient who received a stem cell transplant for chronic lymphocytic leukemia. Pulmonary alveolar proteinosis was cured after stopping sirolimus without any other therapeutic management. PAP can be a rare but serious side effect of sirolimus. It is important to rule out other causes of primary or secondary PAP before suggesting a toxic drug cause. The main challenge is to quickly diagnose this side effect to stop exposure to the toxic agent.

Immunodeficiency and Autoantibodies to Cytokines

BACKGROUND

Anti-cytokine autoantibodies (AAbs) associated with an infectious phenotype are now included along with anti-complement AAbs and somatic pathogenic gene variants as a distinct category termed 'phenocopies of primary immunodeficiencies' in the classification of inborn errors of immunity. Anti-cytokine AAbs target specific cytokine pathways, leading to inordinate susceptibility to specific organisms, generally in the setting of immunocompetence.

CONTENT

Anti-cytokine AAbs are detected in the majority of healthy individuals and may play a regulatory role in limiting exaggerated responses to cytokines. While it is not well understood why some individuals with anti-cytokine AAbs develop increased susceptibility to organisms of low pathogenicity and others do not, it is likely that genetics and environment play a role. To date, AAbs to interferon gamma (IFNγ), interferon alpha (IFNα), interleukins-17 and 22 (IL-17/IL-22), interleukin-6 and granulocyte macrophage colony stimulating factor (GM-CSF) and their association with increased susceptibility to nontuberculous mycobacteria and other intracellular organisms, viral infections, Candida albicans, Staphylococcus aureus and other pyogenic organisms, and fungal infections respectively, have been described. The clinical phenotype of these patients is very similar to that of individuals with pathogenic gene variants in the specific cytokine pathway that the autoantibody targets, hence the term 'phenocopy.' Recognition of anti-cytokine AAbs as a distinct cause of immunodeficiency or immune dysregulation is important for appropriate management of such patients.

SUMMARY

Understanding the roles that anti-cytokine AAbs play in health and disease continues to be a fascinating area of research. Evaluating generally immunocompetent individuals who present with chronic, treatment refractory, or unusual infections for anti-cytokine AAbs is critical as it may direct therapy and disease management.

Sirolimus-induced secondary pulmonary alveolar proteinosis

Pulmonary alveolar proteinosis (PAP) is a rare pulmonary syndrome that is characterized by the accumulation of excess surfactant in the alveolar space, leading to impaired gas exchange. Sirolimus-induced PAP is an extremely rare entity that has only been described in the literature in a small number of case reports. We present a case of a 39-year-old female with acute lymphocytic leukemia who underwent stem cell transplant, complicated by graft-versus-host-disease (GVHD) involving the skin for which she was treated with steroids, photopheresis, sirolimus, and ruxolitinib. She was admitted to the intensive care unit (ICU) for acute on chronic hypoxic respiratory failure requiring intermittent mechanical ventilation. Computed tomography (CT) of the chest showed thickened inter- and intralobular septa with ground glass opacities and consolidation with a limited geographic pattern. Bronchoalveolar lavage fluid was stained with Periodic acid-Schiff (PAS), which was positive for extracellular proteinaceous material. Autoimmune studies including antibody levels for primary autoimmune pulmonary alveolar proteinosis (PAP) were negative. The patient was diagnosed with sirolimus-induced secondary PAP, and sirolimus was discontinued. A year later, she no longer required supplemental oxygen, and repeat CT imaging showed only faint residual disease. This is the only documented case of sirolimus-induced PAP in a stem cell transplant recipient and the first case reported in which the patient developed severe hypoxic respiratory failure requiring mechanical ventilation. In the right clinical context, PAP can be diagnosed with characteristic high resolution computed tomography (HRCT) findings, serum GM-CSF antibody levels, and bronchoscopy with bronchoalveolar lavage.

Pulmonary alveolar proteinosis due to heterozygous mutation in OAS1: Whole lung lavages for long-term bridging to hematopoietic stem cell transplantation

INTRODUCTION

Pulmonary alveolar proteinosis (PAP) is defined by increased accumulation of surfactant in the alveolar space. PAP has been reported to be associated with a large number of clinical conditions and diseases. Whole lung lavages (WLLs) can be helpful to stabilize the clinical course of PAP until the underlying condition is identified, which may enable more specific treatment. Recently, heterozygous OAS1 gain-of-function variants were described as cause in patients with infantile-onset PAP combined with hypogammaglobulinemia.

CASE PRESENTATION

At age 4 months, a female infant born to term was diagnosed with hypogammaglobulinemia and treated with monthly immunoglobulin injections. At age 15 months, the girl needed supplemental oxygen at night, and at age 18 months, also during the day. At age 2 years, PAP of unknown etiology was diagnosed by computed tomography scan and open lung biopsy. Subsequently, monthly WLLs were started, which stabilized the clinical course for over 2 years until a disease-causing OAS1 variant was diagnosed and the patient was successfully treated by hematopoietic stem cell transplantation (HSCT).

CONCLUSION

Here, we describe the successful management of a female patient with severe PAP caused by a heterozygous OAS1 gain-of-function variant until a definitive diagnosis was made and cured by HSCT.

Whole lung lavage: Treating pulmonary alveolar proteinosis at the time of COVID pandemic

Pulmonary alveolar proteinosis (PAP) is a rare syndrome due to increased production or decreased clearance of surfactant in alveoli and terminal bronchi that cause hypoxemic respiratory insufficiency. Here we present a patient with PAP whose disease was exacerbated by superimposed COVID-19 pneumonia. He underwent whole lung lavage (WLL). Evaluation of the viral count of the first and the last lavage of the left lung showed viral load in the alveolar space dropped by approximately 10-folds, however the magnitude of the viral load was substantial in both lavage samples. Whole pulmonary lavage may be used as a treatment option on patients with PAP even when the disease is exacerbated by COVID-19 pneumonia.

The Role of GM-CSF Autoantibodies in Infection and Autoimmune Pulmonary Alveolar Proteinosis: A Concise Review

Autoantibodies to multiple cytokines have been identified and some, including antibodies against granulocyte-macrophage colony-stimulating factor (GM-CSF), have been associated with increased susceptibility to infection. High levels of GM-CSF autoantibodies that neutralize signaling cause autoimmune pulmonary alveolar proteinosis (aPAP), an ultrarare autoimmune disease characterized by accumulation of excess surfactant in the alveoli, leading to pulmonary insufficiency. Defective GM-CSF signaling leads to functional deficits in multiple cell types, including macrophages and neutrophils, with impaired phagocytosis and host immune responses against pulmonary and systemic infections. In this article, we review the role of GM-CSF in aPAP pathogenesis and pulmonary homeostasis along with the increased incidence of infections (particularly opportunistic infections). Therefore, recombinant human GM-CSF products may have potential for treatment of aPAP and possibly other infectious and pulmonary diseases due to its pleotropic immunomodulatory actions.

One-session bilateral sequential whole lung lavage (OSBSWLL) for the management of pulmonary alveolar proteinosis

BACKGROUND

Whole Lung Lavage (WLL) has been an important part in the management of Pulmonary Alveolar Proteinosis (PAP) since it improves radiologic and clinical parameters. Bilateral WLL is usually performed in two sessions on different days. Few case reports have described one-session bilateral sequential lung lavage (OSBSWLL), and none have described ambulatory management (same-day discharge).

METHODS

Demographic characteristics, physiologic parameters, procedure details and outcomes were retrospectively collected on consecutive patients who underwent OSBSWLL for PAP following an ambulatory protocol stablished in our institution.

RESULTS

A total of 13 patients underwent 30 OSBSWLL (61.5% male; mean age 40). The mean SpO2 was 90% (IQR 9) and 94% (IQR 6), before and after OSBSWLL respectively. In 63.3% of cases, patients were discharged home the same day of procedure. Only in two cases (6.6%), patients required post-procedure prolonged mechanical ventilation (> 4 h) due to persistent hypoxia.

CONCLUSIONS

OSBSWLL can be performed with same-day discharge.

Power washing pulmonary alveolar proteinosis

Pulmonary alveolar proteinosis is an uncommon cause of insidious onset shortness of breath and hypoxemia. It is caused by an accumulation of surfactant within the alveoli. Left untreated, it can be fatal. Standard-of-care treatment is whole-lung lavage; however, in severe cases, the associated hypoxemia can be profound and single-lung ventilation would not be tolerated, potentially preventing a lifesaving treatment. Single cases using veno-venous extracorporeal membrane oxygenation to perform whole-lung lavage have been reported. Here we describe three patients with severe pulmonary alveolar proteinosis who were successfully treated with whole-lung lavage using veno-venous extracorporeal membrane oxygenation for oxygenation support.

ABCG1 and ABCG4 as key transporters in the development of pulmonary alveolar proteinosis by nanoparticles

Pulmonary alveolar proteinosis (PAP) has been reported in rodents treated with nanoparticles (NPs). However, little is known about the type of NPs producing PAP and their toxicity mechanisms. Here, we assembled seven PAP-inducing NPs and TiO₂ NPs as a negative control. At 1 and 6 months after a single intratracheal instillation in rats, pulmonary inflammation and the gene expression of ATP-binding cassette (ABC) transporters and related genes were evaluated in separated alveolar macrophages (AMs). One month after intratracheal instillation, seven NPs (Eu₂O₃, In₂O₃, Pr₆O₁₁, Sm₂O₃, Tb₄O₇, and NiO) caused PAP, but only In₂O₃ NPs caused persistent PAP at 6 months after treatment. The levels of phospholipids, indicators of PAP, showed good correlations with the gene expression profile of five transporters (ABCA1, ABCB4, ABCB8, ABCG1, and ABCG4), which effluxing phospholipids in AMs. Among them, ABCG1 and ABCG4 might be key transporters involved in PAP development because both showed a negative correlation with the magnitude of PAP, while others might be compensatory transporters for PAP recovery, as they showed a positive correlation. In conclusion, the identification of seven PAP-producing NPs implies that PAP may be an emerging occupational disease and that ABCG1 and ABCG4 may be therapeutic targets for PAP.