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.

[Lung involvement in autoinflammatory diseases]. / Atteinte pulmonaire dans les maladies auto-inflammatoires.

Genetic autoinflammatory diseases are now a recognized and rapidly expanding group. The lung involvement historically associated with autoinflammatory diseases is inflammatory seritis, primarily seen in familial Mediterranean fever and other interleukin-1 mediated diseases. Over the last ten years, pulmonary involvement has been the core presentation of two autoinflammatory diseases associated with constitutive type I interferon activation, i.e. SAVI and COPA syndrome. Most patients with these diseases usually develop early progression to pulmonary fibrosis, which is responsible for high rates of morbidity and mortality. Other rare autoinflammatory diseases are associated with alveolar proteinosis, particularly when related to MARS mutations. Additionally, in adults, VEXAS is frequently associated with pulmonary involvement, albeit without prognosis effect. A molecular approach to autoinflammatory diseases enables not only the definition of biomarkers for diagnosis, but also the identification of targeted treatments. Examples include JAK inhibitors in SAVI and COPA syndrome, even though this therapy does not prevent progression to pulmonary fibrosis. Another illustrative example is the efficacy of methionine supplementation in alveolar proteinosis linked to MARS mutations. Overall, in autoinflammatory diseases the lung is now emerging as a possible affected organ. Continuing discovery of new autoinflammatory diseases is likely to uncover further pathologies involving the lung. Such advances are expected to lead to the development of novel therapeutic perspectives.

The impact of lung ultrasound assessment during a whole lung lavage: A paediatric case of pulmonary alveolar proteinosis.

Whole lung lavage (WLL) is the first-line treatment for pulmonary alveolar proteinosis. We hypothesized that lung ultrasound (LUS) would guide flooding during treatment in a 15-year-old boy. WLL of each lung consisted of instillation of saline followed by kinesiotherapy and fluid drainage. In the first WLL, the lung was repeatedly flooded until the lavage fluid was clear on macroscopic examination. During this process, LUS was used to visualise lung aeration. In the second WLL, we used LUS signs to guide the lavage volume. The appearance of the fluid bronchogram sign showed that saline infusion could be stopped earlier than in the first lavage. In conclusion, LUS helped monitor the different stages of controlled lung de-aeration during WLL and reduce the total amount of saline used. This technique will also reduce the risk of WLL-related complications.

Whole lung lavage decreases physiological dead space in patients with pulmonary alveolar proteinosis: two case reports.

BACKGROUND: Pulmonary alveolar proteinosis (PAP) is a rare disease characterized by progressive accumulation of the alveolar surfactant. Whole lung lavage (WLL) using a high volume of warmed saline remains the standard therapy. However, no established bedside monitoring tool can evaluate the physiological effect of WLL in the perioperative period. Indirect calorimetry, which is generally used to measure resting energy expenditure, can detect carbon dioxide (CO2) production and mixed-expired partial pressure of CO2 breath by breath. In this physiological study, we calculated CO2 elimination per breath (VTCO2,br) and Enghoff's dead space using indirect calorimetry and measured the extravascular lung water index to reveal the effect of WLL. CASE PRESENTATION: We measured VTCO2,br, Enghoff's dead space, and the extravascular lung water and cardiac indices before and after WLL to assess the reduction in shunt by washing out the surfactant. A total of four WLLs were performed in two PAP patients. The first case involved an Asian 62-year-old man who presented with a 3-month history of dyspnea on exertion. The second case involved an Asian 48-year-old woman with no symptoms. VTCO2,br increased, and the Enghoff's dead space decreased at 12 h following WLL. An increase in the extravascular lung water was detected immediately following WLL, leading to a transient increase in Enghoff's dead space. CONCLUSION: WLL can increase efficient alveolar ventilation by washing out the accumulated surfactant. However, the lavage fluid may be absorbed into the lung tissues immediately after WLL and result in an increase in the extravascular lung water.

Pulmonary alveolar proteinosis - current and future therapeutical strategies.

PURPOSE OF REVIEW: We discuss the most recent advances in the treatment of pulmonary alveolar proteinosis (PAP), an ultra-rare syndrome. RECENT FINDINGS: Whole lung lavage (WLL) remains the gold standard of treatment for PAP syndrome. For the autoimmune form, recent trials with recombinant human granulocyte-macrophage colony-stimulating factor (GM-CSF) confirmed the efficacy in up to 70% of cases, especially under continuous administration. In patients with hereditary PAP with underlying GM-CSF receptor mutations, ex vivo autologous hematopoietic stem-cell gene therapy and transplantation of autologous ex vivo gene-corrected macrophages directly into the lungs are promising approaches. SUMMARY: There are no drugs approved for PAP at present, but cause-based treatments such as GM-CSF augmentation and pulmonary macrophage transplantation are paving the way for targeted therapy for this complex syndrome.

[Research progress of cell therapy in hereditary pulmonary alveolar proteinosis].

Hereditary pulmonary alveolar proteinosis (hPAP) is a rare interstitial lung disease caused by mutation in CSF2RA/CSF2RB, characterized by the deposition of pulmonary surfactant due to the alveolar macrophage dysfunction. The whole lung lavage can effectively alleviate the symptoms but is associated with potential complications. Cell therapy is a novel approach with advances that provide a new therapeutic strategy for the treatment of hPAP.

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.

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.

CD40LG-associated X-linked Hyper-IgM Syndrome (XHIGM) with pulmonary alveolar proteinosis: a case report.

BACKGROUND: D40LG-associated X-linked hyper-IgM syndrome with pulmonary alveolar proteinosis has rarely been reported, and its genotype-phenotypic correlation remains elusive. CASE PRESENTATION: We describe a five-month-old boy with CD40LG mutation (c.516T > A, p.Tyr172Ter) X-linked hyper-IgM syndrome with pulmonary alveolar proteinosis as the first manifestation. The patient completely recovered after immunotherapy and allogeneic hematopoietic stem cell transplantation. In addition, four previously reported patients with CD40LG mutation with pulmonary alveolar proteinosis were also analyzed. All of these patients presented with early onset of pulmonary infections and a good response to immunotherapy. The structural model of CD40LG indicated that all mutations caused the X-linked hyper-IgM syndrome with pulmonary alveolar proteinosis to be located within the tumor necrosis factor homology domain. CONCLUSIONS: A case was presented, and the characteristics of four cases of CD40LG-associated X-linked hyper-IgM syndrome with pulmonary alveolar proteinosis were summarized. The variant locations may explain the phenotypic heterogeneity of patients with the CD40LG mutation.

Successful allogeneic hematopoietic stem cell transplantation for myelodysplastic neoplasms complicated with secondary pulmonary alveolar proteinosis and Behçet's disease harboring GATA2 mutation.

Myelodysplastic neoplasms (MDS) are defined by cytopenia and morphologic dysplasia originating from clonal hematopoiesis. They are also frequently complicated with diseases caused by immune dysfunction, such as Behçet's disease (BD) and secondary pulmonary alveolar proteinosis (sPAP). MDS with both BD and sPAP is extremely rare, and their prognosis is poor. In addition, haploinsufficiency of the hematopoietic transcription factor gene GATA2 is recognized as a cause of familial MDS and is frequently complicated by sPAP. Herein, we report a case of MDS combined with both BD and sPAP in association with GATA2 deficiency in a Japanese woman. Because she developed progressive leukopenia and macrocytic anemia during BD treatment at the age of 61, she underwent a bone-marrow examination and was diagnosed with MDS. She subsequently developed sPAP. At the age of 63, she underwent allogeneic hematopoietic stem cell transplantation (allo-HSCT). Since allo-HSCT, she has maintained complete remission of MDS as well as the symptoms of BD and sPAP. Furthermore, we performed whole exome sequencing and identified the GATA2 Ala164Thr germline mutation. These findings suggest that patients with MDS, BD and sPAP should be considered for early allo-HSCT.

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.

Association between one-session bilateral whole-lung lavage and periprocedural complications in patients with pulmonary alveolar proteinosis: a retrospective cohort study.

BACKGROUND: Whole lung lavage (WLL) has been recognized as the most effective therapy of severe pulmonary alveolar proteinosis (PAP). Most centers perform the lavage of each lung in two sessions under general anesthesia at an interval of several days to weeks. Compared with two-session WLL, one-session bilateral sequential WLL only requires general anesthesia once. However, the safety of one-session WLL in PAP patients has not been assessed by large cohort studies. In this study, we aimed to investigate the association between the mode of WLL procedure (one-session or two-session) and the risk of periprocedural complications in PAP patients. METHODS: In this single-center retrospective cohort study, we included adult patients who were diagnosed as PAP and had undergone WLL procedures under general anesthesia from 2000 to 2022. Patients requiring extra-corporeal oxygenation during WLL were excluded. Since some patients received multiple WLL procedures, we considered each procedure in one-session or two-session group as a unique unit in our analysis. The primary outcome was the occurrence of any complications during hospitalization, including termination of WLL procedure due to fluid leakage or refractory hypoxemia, bronchospasm, delayed endotracheal extubation, cardiovascular event, pneumothorax, and fever. RESULTS: We included a total of 175 WLL procedures (118 patients), with 48 in the two-session group and 127 in the one-session group. Periprocedural complications occurred in 17 (35.4%) and 39 (30.7%) procedures in the two-session and the one-session groups, respectively. The risk of periprocedural complications did not differ significantly between groups, after adjusting the unbalanced confounders in a multivariable model (odds ratio 0.95, 95% confidence interval 0.34 to 2.69, P 0.929) or by inverse probability of treatment weighting (odds ratio 0.70, 95% confidence interval 0.30 to 1.54, P 0.379). Compared with the two-session WLL group, the one-session WLL group had a shorter postprocedural length of hospitalization and comparable decrease in alveolar-arterial oxygen tension gradient from baseline. CONCLUSIONS: One-session bilateral WLL was not associated with an increased risk of periprocedural complications compared with two-session WLL in PAP patients. Experienced physicians may consider performing one-session WLL in view of the comparable safety and efficacy and potential advantages of saving time.

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.

Autoimmune Pulmonary Alveolar Proteinosis during the Treatment of Idiopathic Inflammatory Myopathy.

Approximately 50% of idiopathic inflammatory myopathies (IIMs) are associated with interstitial lung disease (ILD). Typically, IIM-ILD manifests as nonspecific interstitial pneumonia. We herein report a rare case of a 78-year-old man with autoimmune pulmonary alveolar proteinosis (PAP) that developed during IIM treatment. The diagnosis of autoimmune PAP was based on detecting anti-granulocyte-macrophage colony-stimulating factor antibodies. We postulated that PAP may have been induced by IIM treatment with prednisolone. Our case suggests that the possibility of autoimmune PAP should be considered in patients with lung lesions during the clinical course of IIM.

[Interstitial lung diseases in children of genetic origin]. / Maladies interstitielles pulmonaires de l'enfant d'origine génétique.

Interstitial lung diseases in children of genetic origin. Interstitial lung disease (ILD) in children (chILD) encompasses a heterogeneous group of rare respiratory disorders, most of which are chronic and severe. In more and more of these cases, a genetic cause has been identified. As of now, the main mutations have been localized in the genes encoding the surfactant proteins (SP)-C (SFTPC), SP-B (SFTPB), their transporter ATP-binding cassette, family 1, member 3 (ABCA3), transcription factor NK2 homeobox 1 (NKX2-1) and, more rarely, SP-A1 (SFTPA1) or SP-A2 (SFTPA2). Pediatric pulmonary alveolar proteinosis (PAP) is associated with mutations in CSF2RA, CSF2RB, and MARS; more recently, mutations in STING1 and COPA have been associated with specific auto-inflammatory disorders including ILD manifestations. The relationships between the molecular abnormalities and the phenotypic expressions generally remain poorly understood. In the coming years, it is expected that newly identified molecular defects will help to more accurately predict disease courses and to produce individualized targeted therapies.