Pulmonary alveolar proteinosis

Recurrent pulmonary alveolar proteinosis after lung transplantation: a case series

Pulmonary alveolar proteinosis (PAP) is a rare lung disorder that is characterized by the accumulation of proteinaceous material in the alveoli, leading to dyspnea, pulmonary fibrosis and potentially death. Lung transplantation represents the ultimate treatment option in patients with end-stage or refractory PAP. So far, post-transplant recurrence of PAP has been reported in only three individual cases worldwide. Moreover, there are no reported cases of PAP recurrence post-transplantation in existing patient registries. The detection of recurrent PAP presents a significant challenge after transplantation, given the high prevalence of infectious and immunological conditions in the differential diagnosis. Herein, we report PAP recurrence in three patients who underwent lung transplantation for PAP at our center, confirmed through CT imaging and histological findings. PAP recurrence in two patients with prior autoimmune PAP appears to have a mild clinical course, while a fatal course of PAP recurrence was observed in a patient with prior secondary PAP. Considering all reported cases, PAP recurrence was observed across all forms of pre-transplant PAP, contributing to death in three of the six cases. We call for increased awareness of this potentially underdiagnosed complication in patients undergoing lung transplantation due to PAP.

The Application of Transbronchial Cryo-biopsy in the Diagnosis of Pulmonary Alveolar Proteinosis

BACKGROUND

Pulmonary alveolar proteinosis (PAP) is a rare disease characterized by abnormal alveolar surfactant accumulation. In recent years, transbronchial cryo-biopsy (TBCB) has gradually been applied as it can obtain larger and better-quality specimens. This study aims to assess the diagnostic yield and safety of TBCB in PAP.

METHODS

This study included 78 PAP patients who underwent lung biopsy. Thirty-six of them underwent transbronchial lung biopsy (TBLB) with forceps and the other 42 underwent TBCB. Clinical data, biopsy specimen number and size, the pathologic lesion proportion of biopsied specimens, complications, and pathologic diagnosis of patients from both groups were recorded.

RESULTS

Our data show that the diagnostic yield of TBCB is significantly superior to that of TBLB (78.6% vs. 50%, P<0.05). The TBCB group exhibited a greater number and size of biopsy specimens than the TBLB group (P<0.05). As for pathologic diagnosis, the specimen size in the PAP-positive group was notably larger than in the PAP-negative group (P<0.05). According to the receiver operating characteristic curve, the specimen size of at least 2 mm2 was identified as the cut-off with a higher positive predictive value (area under the curve = 0.676, P=0.007). For complications of TBLB and TBCB, there was no statistically significant difference in the incidence of pneumothorax and bleeding.

CONCLUSION

TBCB emerges as a minimally invasive, effective, and safe technique with a higher diagnostic yield than TBLB in PAP. Augmenting the specimen size can effectively improve the diagnostic yield.

Anti-cytokine autoantibodies in human susceptibility to infectious diseases: insights from Inborn errors of immunity

The study of Inborn Errors of Immunity (IEIs) is critical for understanding the complex mechanisms of the human immune response to infectious diseases. Specific IEIs, characterized by selective susceptibility to certain pathogens, have enhanced our understanding of the key molecular pathways and cellular subsets involved in host defense against pathogens. These insights revealed that patients with anti-cytokine autoantibodies exhibit phenotypes similar to those with pathogenic mutations in genes encoding signaling molecules. This new disease concept is currently categorized as 'Phenocopies of IEI'. This category includes anti-cytokine autoantibodies targeting IL-17/IL-22, IFN-γ, IL-6, GM-CSF, and type I IFNs. Abundant anti-cytokine autoantibodies deplete corresponding cytokines, impair signaling pathways, and increase susceptibility to specific pathogens. We herein demonstrate the clinical and etiological significance of anti-cytokine autoantibodies in human immunity to pathogens. Insights from studies of rare IEIs underscore the pathological importance of cytokine-targeting autoantibodies. Simultaneously, the diverse clinical phenotype of patients with these autoantibodies suggests that the influences of cytokine dysfunction are broader than previously recognized. Furthermore, comprehensive studies prompted by the COVID-19 pandemic highlighted the substantial clinical impact of autoantibodies and their potential role in shaping the outcomes of infectious disease.

Exogenous GM-CSF therapy for autoimmune pulmonary alveolar proteinosis: a systematic literature review

Background

Granulocyte-macrophage colony-stimulating factor (GM-CSF) therapy is an important treatment for autoimmune pulmonary alveolar proteinosis (aPAP). Exogenous GM-CSF treatment can be administered either through subcutaneous injection or nebulized inhalation. However, data on the effectiveness and safety of these two approaches are lacking.

Method

We conducted a systematic literature review of different methods, including subcutaneous injection and nebulized inhalation of GM-CSF, for the treatment of aPAP patients. Patients were divided into a subcutaneous injection group (SIG) and a nebulized inhalation group (NIG) according to the route of administration. Treatment efficacy and safety, including adverse events, were statistically assessed. We analyzed different GM-CSF treatment cycles with different time intervals. The analyses were performed using chi-square tests, unpaired t-tests, and Kruskal-Wallis H-tests.

Results

A total of 304 aPAP patients were treated with GM-CSF, including 66 (21.7%) in the SIG and 238 (78.3%) in the NIG. In total, we identified 220 (72.37%) patients whose treatment was effective and 84 (27.63%) patients whose treatment was ineffective. Efficacy was achieved in 54.55% (36/66) of the SIG patients and 77.31% (184/238) of the NIG patients (P < 0.001). More metrics were changed than in the NIG than SIG, suggesting the superior effectiveness of nebulized inhalation. The nebulized inhalation of GM-CSF was more effective (P < 0.001) and caused fewer adverse events than its subcutaneous injection. A significant difference in the NIG was noted across treatment durations, with an efficacy rate of 88% for those treated for over 24 weeks, compared with 48% in the SIG (P < 0.001). Among the NIG patients, the optimal efficacy was found to be at a dosage of 300-400 μg/d, with diminishing efficacy at higher doses (P < 0.036).

Conclusion

Nebulized inhalation is a more effective and safer route of GM-CSF administration than subcutaneous injection is, with a potential optimal dosage of 300-400 μg/day, and the duration of GM-CSF treatment via nebulized inhalation with the greatest efficacy is >24 weeks.

Evaluating the evidence for GM-CSF as a host-directed therapy in respiratory infections

Novel therapeutic approaches are needed to treat respiratory infections due to the rising antimicrobial resistance and the lack of effective antiviral therapies. A promising avenue to overcome treatment failure is to develop strategies that target the host immune response rather than the pathogen itself. Granulocyte-macrophage colony-stimulating factor (GM-CSF) plays a critical role in controlling homeostasis in lungs, alveolar macrophages being the most sensitive cells to GM-CSF signaling. In this review, we discuss the importance of GM-CSF secretion for lung homeostasis and its alteration during respiratory infections. We also present the pre-clinical evidence and clinical investigations evaluating GM-CSF-based treatments (administration or inhibition) as a therapeutic strategy for treating respiratory infections, highlighting both supporting and contradictory findings.

Transcriptomics of Various Diseases Reveals the Core Role of Immune System Pathways in Retinal Damage Repair and Nerve Regeneration

Retinal ganglion cells (RGCs) are the only neuronal bridges connecting retinal inputs to the brain's visual processing centers, enabling visual perception. The axon of RGCs forms the optic nerve, which transmits visual information to the visual cortex. Damage to RGCs and their axons results in irreversible visual impairment. Acute retinal damage is commonly induced by conditions such as optic nerve compression, glaucoma, and optic neuritis, for which effective clinical treatments are currently unavailable. Therefore, understanding the response of RGCs and their axons to injury is crucial for the development of potential treatments. This study utilizes multiple models including optic nerve crush (ONC), acute intraocular pressure (IOP) elevation, and local lipopolysaccharide (LPS) injection into the optic nerve to mimic eye diseases. Three days post-surgery, mice underwent retinal isolation followed by bulk-RNA sequencing to analyze differential gene expression among models. Using thresholds of |Log2 fold change (FC)|> 2 and p-value < 0.05, the significant gene expression changes observed in each model were as follows: ONC (upregulated, 456; downregulated, 84), IOP (upregulated, 1946; downregulated, 655), and LPS (upregulated, 219; downregulated, 94). Gene ontology (GO) analysis of the upregulated genes unexpectedly revealed that immune system pathways were the primary shared targets across all three models. In contrast, the downregulated genes exhibited model-specific enrichment: synaptic components and functions in IOP, neurogenesis and neuronal development in ONC, and inflammation and antioxidant in LPS. These findings were further confirmed by Kyoto Encyclopedia of Genes and Genomes (KEGG) analysis. This suggests that managing immune activation is essential for treating acute retinal injury, and therapeutic strategies should address model-specific targets as well. Notably, 39 genes intersected across the models, and the protein-protein interaction (PPI) network identified Ccl5 as a key hub gene, underscoring its critical role in the pathophysiology of all three diseases.

High-frequency jet ventilation in managing airway during whole-lung lavage under general anesthesia: A case report

Pulmonary alveolar proteinosis (PAP) is a rare disorder characterized by the accumulation of surfactant-derived lipoproteins within alveoli and impaired macrophage function, leading to progressive dyspnea, hypoxemic respiratory failure, secondary infections, and pulmonary fibrosis. We report a case of a 43-year-old male with a history of occupational exposure to airborne dust from lathe work, presenting with exertional dyspnea. High-resolution computed tomography (HRCT) revealed bilateral patchy ground-glass opacities with interlobular septal thickening. Histopathological analysis of lung biopsy specimens showed eosinophilic amorphous material in alveolar spaces, which exhibited positive periodic acid-Schiff (PAS) staining with diastase resistance, confirming PAP. The patient underwent whole-lung lavage (WLL) of the right lung under general anesthesia. Severe baseline hypoxemia complicated intraoperative oxygen saturation maintenance. The intermittent use of high-frequency jet ventilation (HFJV) in the operative lung markedly improved oxygenation (SpO2 increased from 85 % to 96 %) while ensuring effective saline distribution into distal alveoli. The procedure was completed without complications, highlighting the efficacy and safety of HFJV in managing complex airway conditions during WLL for PAP.

Summary for clinicians: ERS guidelines on pulmonary alveolar proteinosis

Pulmonary alveolar proteinosis (PAP) is a rare lung disease caused by accumulation of surfactant in the alveoli, leading to debilitating respiratory symptoms and impaired gas exchange. The recent European Respiratory Society guidelines provide evidence-based recommendations for its diagnosis and management. Autoimmune PAP (aPAP) is the most common form, driven by granulocyte-macrophage colony-stimulating factor (GM-CSF) autoantibodies. Recommended diagnostic tools include bronchoalveolar lavage and quantitative GM-CSF antibody testing. Whole lung lavage and inhaled GM-CSF are first-line treatments for symptomatic or progressive aPAP. Rituximab, plasmapheresis, and lung transplantation are options for refractory disease. Referral to expert centres is advised for diagnostic and therapeutic guidance. This case-based summary for clinicians highlights the best clinical approach to patients with suspicion or confirmation of PAP.

The Interplay Between Innate Immunity and Nonimmune Cells in Lung Damage, Inflammation, and Repair

As the site of gas exchange, the lung is critical for organismal survival. It is also subject to continual environmental insults inflicted by pathogens, particles, and toxins. Sometimes, these insults result in structural damage and the initiation of an innate immune response. Operating in parallel, the immune response aims to eliminate the threat, while the repair process ensures continual physiological function of the lung. The inflammatory response and repair processes are thus inextricably linked in time and space but are often studied in isolation. Here, we review the interplay of innate immune cells and nonimmune cells during lung insult and repair. We highlight how cellular cross talk can fine-tune the circuitry of the immune response, how innate immune cells can facilitate or antagonize proper organ repair, and the prolonged changes to lung immunity and physiology that can result from acute immune responses and repair processes.

The Integrated Pulmonary Immune Response to Pneumonia

Pneumonia is an acute respiratory infection of the lower respiratory tract. The effectiveness of the host immune response determines the severity of infection, or whether pneumonia occurs at all. The lungs house both innate and adaptive immune systems, which integrate their activities to provide host defense that eliminates microbes and prevents lower respiratory infection from becoming severe. Professional immune cells in the lung, like macrophages and lymphocytes, work with lung constituents, like epithelial cells and fibroblasts, to optimize antimicrobial defense. The dynamics of the immune response during infection and the immune components contributing to defense are influenced by prior experiences with respiratory pathogens, remodeling lung immunity in ways that improve responses against subsequent infections. This review covers how innate and adaptive immune activities coordinate inside the lung to provide integrated and effective immune resistance against respiratory pathogens.

A patient journey map for people living with autoimmune pulmonary alveolar proteinosis

INTRODUCTION

Patients with autoimmune pulmonary alveolar proteinosis (PAP) face a complicated journey (physically, emotionally, and financially) to receive the correct diagnosis and treatment. We developed a patient journey map (PJM) to describe the experiences and needs of patients with autoimmune PAP in the USA.

METHODS

This PJM was developed in four stages: (1) analysis of existing literature; (2) patient advisory board meetings (n = 7); (3) an online survey (n = 19); and (4) a validation workshop (n = 6).

RESULTS

Four phases of the patient journey were identified: (1) symptoms and experience before diagnosis; (2) diagnosis; (3) treatment; and (4) ongoing monitoring. Patients reported heterogeneous and indirect diagnostic pathways, often waiting months or years for the correct diagnosis. The majority reported at least one misdiagnosis, most commonly pneumonia. Treatment pathways varied substantially, and current treatments and off-label therapies were frequently described as burdensome, emotionally taxing, and/or financially worrisome. Patients described their journey as an "emotional rollercoaster," especially during pre-diagnosis and treatment. Patients reported common barriers to care, particularly insurance problems and access to expert care. Patients specifically cited the need for improved education on autoimmune PAP within the medical community and increased help with insurance challenges related to current treatments.

CONCLUSIONS

This PJM provides insights on patients' journeys with autoimmune PAP. Patients reported inconsistent, burdensome, and circuitous journeys. This PJM provides the medical community with valuable information on patients' needs and increases awareness of this rare disease. Over time, these factors may improve diagnosis, treatment, and the holistic experience of patients with autoimmune PAP.

Diagnostic approach in acute hypoxemic respiratory failure

Acute hypoxemic respiratory failure (AHRF) is the leading cause of intensive care unit (ICU) admissions. Of patients with AHRF, 40 %-50 % will require invasive mechanical ventilation during their stay in the ICU, and 30 %-80 % will meet the Berlin Criteria for Acute Respiratory Distress Syndrome (ARDS). Rapid identification of the underlying cause of AHRF is necessary before initiating targeted treatment. Almost 10 % of patients with ARDS have no identified classic risk factors however, and the precise cause of AHRF may not be identified in up to 15 % of patients, particularly in cases of immunosuppression. In these patients, a multidisciplinary, comprehensive, and hierarchical diagnostic work-up is mandatory, including a detailed history and physical examination, chest computed tomography, extensive microbiological investigations, bronchoalveolar lavage fluid cytological analysis, immunological tests, and investigation of the possible involvement of pneumotoxic drugs.

GM-CSF-mediated epithelial-immune cell cross-talk orchestrates pulmonary immunity to Aspergillus fumigatus

Aspergillus fumigatus causes life-threatening mold pneumonia in immunocompromised patients, particularly in those with quantitative or qualitative defects in neutrophils. Whereas innate immune cell cross-talk licenses neutrophil antifungal activity in the lung, the role of epithelial cells in this process is unknown. Here, we find that surfactant protein C (SPC)-expressing lung epithelial cells integrate infection-induced interleukin-1 and type III interferon signaling to produce granulocyte-macrophage colony-stimulating factor (GM-CSF) preferentially at local sites of fungal infection and neutrophil influx. Using in vivo models that distinguish the role of GM-CSF during acute infection from its homeostatic function in alveolar macrophage survival and surfactant catabolism, we demonstrate that epithelial-derived GM-CSF increases the accumulation and fungicidal activity of GM-CSF-responsive neutrophils, which is essential for host survival. Our findings establish SPC+ epithelial cells as a central player in regulating the quality and strength of neutrophil-dependent immunity against inhaled mold pathogens.

Phenotypic heterogeneity in mortality and prognosis of pulmonary alveolar proteinosis: a large-scale, global pooled analysis of individual-level data

BACKGROUND

Pulmonary Alveolar Proteinosis (PAP) is a rare interstitial lung disease with diverse clinical manifestations and outcomes. However, there are limited data on the heterogeneity of PAP, as well as its prognosis, cause of death and genetic mechanisms. This study aims to elucidate mortality, prognostic features, and genetic mechanisms in patients with PAP.

METHODS

The individual patient data of clinical and mortality were obtained by summarizing the published cases series. Patients with PAP were classified using K-means clustering, and logistic regression identified prognostic factors affecting outcomes. Inheritance and related mechanism of PAP were described by summarizing PAP related genes and enrichment analysis.

FINDINGS

Our analysis included 3278 patients from 295 reports, with 88.6% diagnosed with idiopathic PAP (IPAP). Twelve major categories of cause were counted from 312 deaths (mortality: 9.5%), the most common of which were respiratory failure (45.8%) and lung infections (18.3%). Three symptom-related clusters were identified, and patients with multiple symptoms appeared to have worse mortality than those with single or no symptoms (p < 0.05). Non-secondary patterns (OR 2.87, p = 0.003), whole lung lavage (OR 0.15, p < 0.001), and effective GM-CSF therapy (OR 0.08, p < 0.001) are prognostic factors associated with decreased mortality. Additionally, 134 significant genes related to PAP development were identified, highlighting the roles of immune response and lipid metabolism.

INTERPRETATION

This study comprehensively describes the clinical characteristics cause of death, prognosis and associated factors based on the global PAP population. The significant phenotype heterogeneity highlighting the importance of long-term prognosis and individualized management for patients with PAP.

The healthcare burden of pulmonary alveolar proteinosis (PAP)

INTRODUCTION

Pulmonary alveolar proteinosis (PAP) is a rare lung syndrome characterized by the accumulation of surfactant in the alveoli. Using a longitudinal claims database, we compared measures of clinical and economic burden between a sample of diagnosed PAP patients and non-PAP matched controls.

METHODS

PAP patients were identified leveraging IPM.ai's longitudinal U.S. claims database spanning January 1, 2009, through May 1, 2022. PAP patients were selected based on the presence of ICD-10: J84.01 or ICD-9: 516.0 in their claims history and were indexed for observation. An age, gender, and geographically matched control cohort was created (ratio of 1:4) for comparison. A third cohort, consisting of likely undiagnosed PAP patients, was identified using a machine learning model. The PAP and control cohorts were tracked longitudinally, depending on individual index dates, from January 1, 2018, through May 1, 2023. Inclusion criteria required evidence of continual claims activity 12 months prior to and after the index date, which reduced the total number of diagnosed PAP and control patients in the analysis. Demographics, comorbidities, procedures, medication use, annual healthcare resource utilization (HCRU), and costs were calculated for eligible PAP and control patients and were compared 12 months prior to, and 12 months after each patient's index date.

RESULTS

After inclusion criteria were applied, 2312 confirmed PAP patients and 9247 matched controls were included in the analysis. Compared with matched controls, PAP patients had significantly higher rates of diagnosed conditions at baseline as defined by the Charlson Comorbidity Index (CCI). During the follow-up period, PAP patients had higher rates of diagnosed conditions, procedures, medication use, and cost-of-care compared with controls. PAP patients also had higher rates of emergency room visits (35% vs. 14%; P < 0.001), outpatient visits (87% vs. 56%; P < 0.001), inpatient visits (20% vs. 5%; P < 0.001) and had longer lengths of stay for inpatient hospitalizations (2.8 days vs. 0.56 days; P < 0.001), respectively.

CONCLUSION

This study represents the largest dataset of PAP patients and matched controls to be analyzed to date. Findings indicate that PAP patients have higher rates of diagnosed conditions, procedures, medication use, HCRU, and costs compared with non-PAP patients.

Effect of Whole Lung Lavage for Pulmonary Alveolar Proteinosis on Circulatory Dynamics: A Case Report

Whole lung lavage (WLL) is a standard treatment for severe pulmonary alveolar proteinosis (PAP) and is performed under general anesthesia. However, the management of anesthesia in PAP patients poses significant challenges due to their compromised respiratory function. Additionally, the instillation of large volumes of normal saline during WLL may adversely affect circulatory dynamics. In this case report, we examined the impact of WLL on circulatory parameters in a patient with severe PAP. A 71-year-old male diagnosed with idiopathic PAP underwent WLL under general anesthesia. Each lung was instilled with 1,000 mL of normal saline, followed by drainage in a series of 10 cycles per lung. Hemodynamic parameters were monitored throughout the procedure. Statistical analyses were performed to evaluate changes in circulatory values before and after saline instillation and to compare differences in hemodynamic responses between the right- and left-sided WLL. Our findings demonstrated that saline instillation during WLL significantly suppressed cardiac output. Furthermore, the suppression of circulatory function was more pronounced during right-sided WLL compared with left-sided WLL. These observations highlight the critical need for careful hemodynamic monitoring and management during WLL to ensure patient safety and optimize outcomes.

Mitochondrial Regulator CRIF1 Plays a Critical Role in the Development and Homeostasis of Alveolar Macrophages via Maintaining Metabolic Fitness

The importance of mitochondrial function in macrophages is well established. Alveolar macrophages (AMs), the tissue-resident macrophages (TRMs) of the lung, are particularly dependent on mitochondria-driven oxidative phosphorylation (OXPHOS) to support their functions and maintain homeostasis. However, the specific genes and pathways that regulate OXPHOS in AMs remain unclear. In this study, we investigated the role of CR6-interacting factor 1 (CRIF1), a mitochondrial regulator, as a key factor that specifically modulates the metabolic fitness and maintenance of AMs. Using single-cell RNA sequencing and transcriptomic analyses, we found CRIF1 to be highly expressed in AMs compared to TRMs from other tissues, correlating with enhanced OXPHOS activity. Genetic ablation of Crif1 in macrophages resulted in a marked reduction in AM populations exclusively in the lung, while other TRM populations were unaffected. CRIF1-deficient AMs exhibited an altered metabolic profile, including impaired mitochondrial function, increased glycolysis, and aberrant lipid accumulation. These findings underscore the essential role of CRIF1 in regulating mitochondrial functions and metabolic fitness in AMs, distinguishing it from broader mitochondrial regulators like mitochondrial transcription factor A, which operates across multiple TRM populations. Our study provides critical insights into the tissue-specific regulation of macrophage metabolism and suggests potential therapeutic avenues for lung diseases associated with AM dysfunction.

Induced pluripotent stem cell-derived macrophages as a platform for modelling human disease

Macrophages are innate immune cells that are present in essentially all tissues, where they have vital roles in tissue development, homeostasis and pathogenesis. The importance of macrophages in tissue function is reflected by their association with various human diseases, and studying macrophage functions in both homeostasis and pathological tissue settings is a promising avenue for new targeted therapies that will improve human health. The ability to generate macrophages from induced pluripotent stem (iPS) cells has revolutionized macrophage biology, with the generation of iPS cell-derived macrophages (iMacs) providing unlimited access to genotype-specific cells that can be used to model various human diseases involving macrophage dysregulation. Such disease modelling is achieved by generating iPS cells from patient-derived cells carrying disease-related mutations or by introducing mutations into iPS cells from healthy donors using CRISPR-Cas9 technology. These iMacs that carry disease-related mutations can be used to study the aetiology of the particular disease in vitro. To achieve more physiological relevance, iMacs can be co-cultured in 2D systems with iPS cell-derived cells or in 3D systems with iPS cell-derived organoids. Here, we discuss the studies that have attempted to model various human diseases using iMacs, highlighting how these have advanced our knowledge about the role of macrophages in health and disease.

Granulocyte macrophage colony stimulating factor in virus-host interactions and its implication for immunotherapy

Viruses have evolved to strategically exploit cellular signaling pathways to evade host immune defenses. GM-CSF signaling plays a pivotal role in regulating inflammation, activating myeloid cells, and enhancing the immune response to infections. Due to its central role in the immune system, viruses may target this pathway to further establish infection. This review focuses on key studies elucidating virus interactions with GM-CSF signaling proteins and summarizes findings on the impact of viral infections on GM-CSF production. Additionally, therapeutic strategies centered around GM-CSF are investigated, such as the potential benefits of administering GM-CSF versus inhibiting GM-CSF signaling to mitigate viral-induced aberrant inflammation. Understanding these virus-host interactions provides valuable insights that help further our understanding to develop future therapeutic approaches in modulating the immune response during viral infections.

Menin orchestrates macrophage reprogramming to maintain the pulmonary immune homeostasis

Menin is a scaffold protein encoded by the Men1 gene, and it interacts with a variety of chromatin regulators to activate or repress cellular processes. The potential importance of menin in immune regulation remains unclear. Here, we report that myeloid deletion of Men1 results in the development of spontaneous pulmonary alveolar proteinosis (PAP). This is strongly correlated with impaired development of alveolar macrophages (AM) through inactivation of the granulocyte-macrophage colony-stimulating factor (GM-CSF/CSF2) pathway caused by Men1 deficiency. Mechanistically, menin directly interacts with the SET domain containing 2 (SETD2) through the N-terminal domain (NTD) and Palm domains to maintain protein stability and chromatin recruitment. SETD2 and menin collectively maintain CSF2 expression through H3K36me3, which orchestrates AM reprogramming and pulmonary immune homeostasis. Targeting H3K36me3 remodeling mitigated the aberrant activation of macrophages caused by lipopolysaccharide (LPS). Our results point to a nonredundant role of menin in the control of macrophage lineage maintenance via reinforcement of the H3K36me3 transcriptional program.

Immune-epithelial cell interactions in lung development, homeostasis and disease

The importance of the crosstalk between lung epithelial and immune cells, which emerges from early development and lasts throughout life, is corroborated by a growing body of scientific evidence. This communication not only has a role in driving lung morphogenesis during development, but it is also required in adulthood for the maintenance of homeostasis and repair following infection or injury. Disruption of the intricate immune-epithelial crosstalk can lead to diseases such as COPD and IPF. In this review we summarise the current knowledge regarding the communication between various immune and epithelial cells in development, homeostasis, regeneration and disease, while identifying the current gaps in our knowledge required to facilitate the development of more effective therapies.

Epidemiology of pulmonary alveolar proteinosis: a descriptive study using a Japanese national administrative claims database

The national prevalence of autoimmune and secondary PAP rose during the past decade. The prognoses of secondary and congenital PAP were particularly poor, highlighting the need for further research of the mechanisms underlying these diseases. https://bit.ly/3Z7uBkg.

Interstitial lung disease in the newborn

Although relatively rare, interstitial lung diseases may present with respiratory distress in the newborn period. Most commonly these include developmental and growth disorders, disorders of surfactant synthesis and homeostasis, pulmonary interstitial glycogenosis, and neuroendocrine cell hyperplasia of infancy. Although the diagnosis of these disorders is sometimes made based on clinical presentation and imaging, due to the significant overlap between disorders and phenotypic variability, lung biopsy or, increasingly genetic testing is needed for diagnosis. These diseases may result in significant morbidity and mortality. Effective medical treatment options are in some cases limited and/or invasive. The genetic basis for some of these disorders has been identified, and with increased utilization of exome and whole genome sequencing even before lung biopsy, further insights into their genetic etiologies should become available.

Autoimmune Pulmonary Alveolar Proteinosis: A Rare Diagnosis in Pediatric Age

Autoimmune pulmonary alveolar proteinosis (AI-PAP) is a rare condition, especially in children. The clinical presentation ranges from asymptomatic forms to respiratory distress requiring ventilation. We describe the case of a 13-year-old adolescent male who presented to the emergency department with acute pleuritic chest pain not associated with systemic complaints. On examination, he had diminished breath sounds in the lower two thirds of the chest with no other abnormal findings; SpO2 (oxygen saturation) was 98% on room air. Chest radiograph revealed a marked interstitial infiltrate, comparable with the one taken 4 years earlier during an acute illness that was presumptively treated with azithromycin. A computed tomography (CT) scan revealed multiple bilateral areas of ground-glass opacities with areas of crazy paving, involving > 65% of lung parenchyma, suggestive of pulmonary alveolar proteinosis (PAP). Respiratory viral testing, including for coronavirus (SARS-CoV2), was negative. Bronchoalveolar lavage performed in the outpatient setting revealed a milky fluid and positive periodic acid-Schiff staining. Spirometry indicated a mild restrictive pattern (forced vital capacity [FVC] = 77%) and diffusing capacity of the lungs for carbon monoxide (DLCO) showed a moderate decrease at 48.6%. No mutations associated with surfactant dysfunction were found on the genetic panel. Anti-granulocyte macrophage colony-stimulating factor (GM-CSF) antibody testing was strongly positive, raising suspicion for autoimmune PAP. At 20 months of follow-up, the patient remains asymptomatic with a normal spirometry. Although treatment with agents, such as the inhaled form of granulocyte-macrophage colony-stimulating factor (GM-CSF) appears promising for the treatment of symptomatic adult patients, as this patient remains asymptomatic, a conservative approach was taken, and he continues to be monitored in the clinic.

Pulmonary surfactant biogenesis blockage mediated polyhexamethylene guanidine disinfectant induced pulmonary fibrosis

The widespread use of disinfectants and inhalation exposure to aerosolized forms is closely associated with adverse health effects on the respiratory system and pulmonary fibrosis, but the mechanism remains unclear. Here, we investigated the time-course pulmonary fibrosis effects of polyhexamethylene guanidine (PHMG) disinfectant inhalation exposure and elucidated its underlying mechanism. Specifically, scRNA-seq analysis revealed an initial increase in epithelial cell numbers after 4 weeks of PHMG exposure during induced pulmonary fibrosis, followed by a subsequent decrease after 8 weeks of exposure. Mechanistically, PHMG disrupted autophagic flux leading to intracellular accumulation and blocked pulmonary surfactant biogenesis in alveolar type II epithelial (AT2) cells both in vitro and in vivo. Furthermore, intervention studies using metformin confirmed that autophagy dysfunction mediated the blockage of pulmonary surfactant biogenesis in AT2 cells, playing a pivotal role in PHMG-induced pulmonary fibrosis. Our elucidation of these toxicological mechanisms provides valuable insights into the pathogenesis of pulmonary fibrosis triggered by environmental PHMG exposure, thereby offering a promising therapeutic target for mitigating and treating PHMG-associated pulmonary fibrosis.

Intranasal liposomal angiotensin-(1-7) administration reduces inflammation and viral load in the lungs during SARS-CoV-2 infection in K18-hACE2 transgenic mice

To effectively reduce the health impact of coronavirus disease (COVID-19), it is essential to adopt comprehensive strategies to protect individuals from severe acute respiratory syndrome. In that sense, much effort has been devoted to the discovery and repurposing of effective antiviral and anti-inflammatory molecules. The endogenous peptide angiotensin-(1-7) [Ang-(1-7)] has been recently proposed as a promising anti-inflammatory agent to control respiratory infections. Liposomes also emerged as a safe and effective drug carrier system for local drug delivery to the lungs. In this context, the aim of this study was to develop a liposomal formulation of Ang-(1-7) [LAng (1-7)] and investigate its impact on animal survival as well as its antiviral and anti-inflammatory efficacies after intranasal administration in transgenic K18-hACE2 mice infected with SARS-CoV-2. The liposomal formulation was prepared by the ethanol injection method, exhibiting a mean diameter of 100 nm and a polydispersity index of 0.1. Following treatment of infected mice every 12 hours for 5 days, LAng (1-7) extended animal survival compared to the control groups that received either empty liposomes, free Ang-(1-7), or phosphate-buffered saline. Furthermore, the treatment with LAng (1-7) significantly decreased the viral load, as well as IL-6 and tumor necrosis factor levels in the lungs. Conventional treatment with remdesivir by parenteral route used as a positive control promoted similar effects, leading to improved survival rates and reduced viral load in the lungs without significant effects on IL-6 level. In conclusion, liposomal Ang-(1-7) emerges as a promising formulation to improve the treatment and decrease the severity of respiratory infections, such as COVID-19.

Deep Learning Models of Multi-Scale Lesion Perception Attention Networks for Diagnosis and Staging of Pneumoconiosis: A Comparative Study with Radiologists

Accurate prediction of pneumoconiosis is essential for individualized early prevention and treatment. However, the different manifestations and high heterogeneity among radiologists make it difficult to diagnose and stage pneumoconiosis accurately. Here, based on DR images collected from two centers, a novel deep learning model, namely Multi-scale Lesion-aware Attention Networks (MLANet), is proposed for diagnosis of pneumoconiosis, staging of pneumoconiosis, and screening of stage I pneumoconiosis. A series of indicators including area under the receiver operating characteristic curve, accuracy, recall, precision, and F1 score were used to comprehensively evaluate the performance of the model. The results show that the MLANet model can effectively improve the consistency and efficiency of pneumoconiosis diagnosis. The accuracy of the MLANet model for pneumoconiosis diagnosis on the internal test set, external validation set, and prospective test set reached 97.87%, 98.03%, and 95.40%, respectively, which was close to the level of qualified radiologists. Moreover, the model can effectively screen stage I pneumoconiosis with an accuracy of 97.16%, a recall of 98.25, a precision of 93.42%, and an F1 score of 95.59%, respectively. The built model performs better than the other four classification models. It is expected to be applied in clinical work to realize the automated diagnosis of pneumoconiosis digital chest radiographs, which is of great significance for individualized early prevention and treatment.

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

BACKGROUND

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

METHODS

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

RESULTS

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

CONCLUSIONS

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

Pulmonary fibrosis in patients with autoimmune pulmonary alveolar proteinosis: a retrospective nationwide cohort study

Background

Autoimmune pulmonary alveolar proteinosis (aPAP) is a rare disease that may progress towards pulmonary fibrosis. Data about fibrosis prevalence and risk factors are lacking.

Methods

In this retrospective multicentre nationwide cohort, we included patients newly diagnosed with aPAP between 2008 and 2018 in France and Belgium. Data were collected from medical records using a standardised questionnaire.

Results

61 patients were included in the final analysis. We identified 5 patients (8%) with fibrosis on initial computed tomography (CT) and 16 patients (26%) with fibrosis on final CT after a median time of 3.6 years. Dust exposure was associated with pulmonary fibrosis occurrence (OR 4.3; p=0.038). aPAP patients treated with whole-lung lavage, rituximab or granulocyte-monocyte colony-stimulating factor therapy did not have more fibrotic evolution than patients who did not receive these treatments (n=25 out of 45, 57% versus n=10 out of 16, 62%; p=0.69). All-cause mortality was significantly higher in fibrotic than in nonfibrotic cases (n=4 out of 16, 25% versus n=2 out of 45, 4.4%; p=0.036, respectively).

Conclusion

In our population, a quarter of aPAP patients progressed towards pulmonary fibrosis. Dust exposure seems to be an important factor associated with this complication. More studies are needed to analyse precisely the impact of dust exposure impact, especially silica, in patients with aPAP.

Pulmonary Alveolar Proteinosis During Intensive Immunosuppressive Treatment for Acute Exacerbation of Interstitial Pneumonia: A Case Report and Literature Review

Pulmonary alveolar proteinosis (PAP) is a rare disease characterized by the accumulation of surfactants in the alveoli. It has been suggested that immunosuppressants contribute to the development and exacerbation of PAP. Here, we report the case of a 73-year-old man who developed secondary PAP after intensive immunosuppressive treatment for acute exacerbation of interstitial pneumonia (IP). In this case, despite the improvement of the inflammatory response after immunosuppressive treatment, Krebs von den Lungen-6 (KL-6) continued to increase, leading to the diagnosis of PAP. De-escalation of immunosuppressive treatment improved the PAP, allowing him to be discharged from the hospital. Although KL-6 is a useful marker of IP, when IP appears to be refractory and KL-6 increases despite the improvement of other inflammatory markers, physicians should consider the development of PAP and perform proactive bronchoscopic evaluation.

ABC transporters involved in respiratory and cholestatic diseases: From rare to very rare monogenic diseases

ATP-binding cassette (ABC) transporters constitute a 49-member superfamily in humans. These proteins, most of them being transmembrane, allow the active transport of an important variety of substrates across biological membranes, using ATP hydrolysis as an energy source. For an important proportion of these ABC transporters, genetic variations of the loci encoding them have been correlated with rare genetic diseases, including cystic fibrosis and interstitial lung disease (variations in CFTR/ABCC7 and ABCA3) as well as cholestatic liver diseases (variations in ABCB4 and ABCB11). In this review, we first describe these ABC transporters and how their molecular dysfunction may lead to human diseases. Then, we propose a classification of the genetic variants according to their molecular defect (expression, traffic, function and/or stability), which may be considered as a general guideline for all ABC transporters' variants. Finally, we discuss recent progress in the field of targeted pharmacotherapy, which aim to correct specific molecular defects using small molecules. In conclusion, we are opening the path to treatment repurposing for diseases involving similar deficiencies in other ABC transporters.

Clinical approach for pulmonary alveolar proteinosis in children

In this editorial, we discuss the clinical implications of the article by Zhang et al. Pulmonary alveolar proteinosis (PAP) is a rare lung disease characterized by excessive surfactant accumulation in the alveoli. It is classified into four categories: Primary, secondary, congenital, and unclassified forms. Primary PAP is caused by the disruption of granulocyte-macrophage colony-stimulating factor (GM-CSF) receptor signaling, which is necessary for the clearance of surfactant by alveolar macrophages. It is further divided into autoimmune PAP, caused by anti-GM-CSF antibodies blocking alveolar macrophage activation, and hereditary PAP, resulting from mutations in genes encoding GM-CSF receptors. Secondary PAP develops due to conditions affecting the number or function of alveolar macrophages, such as infections, immunodeficiency, hematological disorders, or exposure to inhaled toxins. Congenital PAP is linked to mutations in genes involved in surfactant protein production. Notably, the causes of PAP differ between children and adults. Diagnostic features include a characteristic "crazy-paving" pattern on high-resolution computed tomography, accompanied by diffuse ground-glass opacities and interlobular septal thickening. The presence of PAP can be identified by the milky appearance of bronchoalveolar lavage fluid and histological evaluation. However, these methods cannot definitively determine the cause of PAP. Whole lung lavage remains the standard treatment, often combined with specific therapies based on the underlying cause.

A 63-Year-Old Presents With Acute Fatigue, Dyspnea, and Hypoxia

CASE PRESENTATION

A 63-year-old woman without significant medical history presented to an urgent care center with a 3-day history of fatigue and dyspnea on exertion. She was found to have an oxygen saturation in the low 80s on room air and was transferred to the closest hospital for further evaluation. Initial chest radiographs showed extensive bilateral interstitial opacities favoring the mid to lower lungs. A general infectious workup was unrevealing. The cause of her symptoms was thought to be an atypical bacterial or viral infection. She was discharged home on supplemental oxygen, 2 L/min via nasal cannula; instructed to finish a 7-day course of antibiotics; and given strict return precautions. Six days later she returned to the ED with worsening dyspnea despite finishing the prescribed course of antibiotics; she was admitted for further evaluation. She had emigrated from Northern India in the early 2000s. While in India, cooking was performed over an open fire. Their home was situated on a poultry farm. She has never smoked. She was up to date on typical cancer screening. She had no pets and denied further exposure to birds since moving to the United States. Her occupational history included manufacturing, but she denied significant exposure to dusts or metal shavings.

Rare genetic interstitial lung diseases: a pictorial essay

The main monogenic causes of pulmonary fibrosis in adults are mutations in telomere-related genes. These mutations may be associated with extrapulmonary signs (hepatic, haematological and dermatological) and typically present radiologically as usual interstitial pneumonia or unclassifiable fibrosis. In children, the monogenic causes of pulmonary fibrosis are dominated by mutations in surfactant-related genes. These mutations are not associated with extrapulmonary signs and often manifest radiologically as unclassifiable fibrosis with cysts that can lead to chest wall deformities in adults. This review discusses these mutations, along with most of the monogenic causes of interstitial lung disease, including interferon-related genes, mutations in genes causing cystic lung disease, Hermansky-Pudlak syndrome, pulmonary alveolar proteinosis, lysinuric protein intolerance and lysosomal storage disorders, and their pulmonary and extrapulmonary manifestations.

Pulmonary alveolar proteinosis: presentation, diagnostic challenges, and management

Pulmonary alveolar proteinosis is a rare diffuse lung disease; diagnosis and treatment of which is often delayed. We present the case study of a 43-year-old male with a six-month history of worsening breathlessness and non-productive cough referred for specialist respiratory input. Rapid investigations, including high-resolution computed tomography (HRCT) and bronchoalveolar lavage, confirmed the diagnosis of pulmonary alveolar proteinosis. Treatment with whole lung lavage significantly improved pulmonary function and quality of life. We discuss the diagnosis and management of this condition and highlight the importance of early recognition and multidisciplinary teamwork in managing pulmonary alveolar proteinosis.

Pulmonary alveolar proteinosis complicated by lung cancer with favorable prognosis: a case report and literature review

With the increasing incidence of lung cancer, the coexistence of pulmonary alveolar proteinosis (PAP) and lung cancer is becoming more common. However, the standard treatment protocols for patients with both conditions are still being explored. The conflict between the rapidly evolving therapeutic approaches for tumors and the limited treatment options for PAP presents a significant challenge for clinicians. Determining the optimal timing of treatment for both conditions to maximize patient benefit is a clinical conundrum. Here, we report a rare case of PAP complicated by lung adenocarcinoma, where interstitial lung changes worsened after neoadjuvant therapy but improved significantly following surgical resection of the lung adenocarcinoma. This case highlights the importance of prioritizing tumor treatment in patients with lung cancer complicated by PAP and examines the interplay between the two conditions, as well as potential therapeutic strategies.

Inherited human RelB deficiency impairs innate and adaptive immunity to infection

We report two unrelated adults with homozygous (P1) or compound heterozygous (P2) private loss-of-function variants of V-Rel Reticuloendotheliosis Viral Oncogene Homolog B (RELB). The resulting deficiency of functional RelB impairs the induction of NFKB2 mRNA and NF-κB2 (p100/p52) protein by lymphotoxin in the fibroblasts of the patients. These defects are rescued by transduction with wild-type RELB complementary DNA (cDNA). By contrast, the response of RelB-deficient fibroblasts to Tumor Necrosis Factor (TNF) or IL-1β via the canonical NF-κB pathway remains intact. P1 and P2 have low proportions of naïve CD4+ and CD8+ T cells and of memory B cells. Moreover, their naïve B cells cannot differentiate into immunoglobulin G (IgG)- or immunoglobulin A (IgA)-secreting cells in response to CD40L/IL-21, and the development of IL-17A/F-producing T cells is strongly impaired in vitro. Finally, the patients produce neutralizing autoantibodies against type I interferons (IFNs), even after hematopoietic stem cell transplantation, attesting to a persistent dysfunction of thymic epithelial cells in T cell selection and central tolerance to some autoantigens. Thus, inherited human RelB deficiency disrupts the alternative NF-κB pathway, underlying a T- and B cell immunodeficiency, which, together with neutralizing autoantibodies against type I IFNs, confers a predisposition to viral, bacterial, and fungal infections.

Syndromic genetic causes of pulmonary fibrosis

PURPOSE OF REVIEW

The identification of extra-pulmonary symptoms plays a crucial role in diagnosing interstitial lung disease (ILD). These symptoms not only indicate autoimmune diseases but also hint at potential genetic disorders, suggesting a potential overlap between genetic and autoimmune origins.

RECENT FINDINGS

Genetic factors contributing to ILD are predominantly associated with telomere (TRG) and surfactant-related genes. While surfactant-related gene mutations typically manifest with pulmonary involvement alone, TRG mutations were initially linked to syndromic forms of pulmonary fibrosis, known as telomeropathies, which may involve hematological and hepatic manifestations with variable penetrance. Recognizing extra-pulmonary signs indicative of telomeropathy should prompt the analysis of TRG mutations, the most common genetic cause of familial pulmonary fibrosis. Additionally, various genetic diseases causing ILD, such as alveolar proteinosis, alveolar hemorrhage, or unclassifiable pulmonary fibrosis, often present as part of syndromes that include hepatic, hematological, or skin disorders.

SUMMARY

This review explores the main genetic conditions identified over the past two decades.

Innovations in the care of childhood interstitial lung disease associated with connective tissue disease and immune-mediated disorders

Childhood interstitial lung disease (chILD) associated with connective tissue and immune mediated disorders is the second most common chILD diagnostic category. As knowledge of the molecular and genetic underpinnings of these rare disorders advances, the recognized clinical spectrum of associated pulmonary manifestations continues to expand. Pulmonary complications of these diseases, including ILD, confer increased risk for morbidity and mortality and contribute to increased complexity for providers tasked with managing the multiple organ systems that can be impacted in these systemic disorders. While pulmonologists play an important role in diagnosis and management of these conditions, thankfully they do not have to work alone. In collaboration with a multidisciplinary team of subspecialists, the pulmonary and other systemic manifestations of these conditions can be managed effectively together. The goal of this review is to familiarize the reader with the classic patterns of chILD and other pulmonary complications associated with primary immune-mediated disorders (monogenic inborn errors of immunity) and acquired systemic autoimmune and autoinflammatory diseases. In addition, this review will highlight current, emerging, and innovative therapeutic strategies and will underscore the important role of multidisciplinary management to improving outcomes for these patients.

Lung biopsy in the diagnosis and management of chILD

Children's interstitial and diffuse lung disease (chILD) comprises a large number of diverse entities ranging from disorders of lung development, maturation and function unique in infancy to immune-mediated, environmental, vascular and other conditions overlapping with adult disease. Pathologic evaluation of the lung has played a central role in characterizing many of these disorders, resulting in revised nomenclature and classifications to help guide clinical management(1-4). Technological advancements are rapidly uncovering genetic and molecular underpinnings of these conditions, as well as widening the phenotypes which bridge adult disease, often reducing the perceived need for diagnostic lung biopsy. As such the decision to get a lung biopsy in chILD is frequently for rapid ascertainment of disease in a critically ill child or when clinical presentation, imaging and laboratory studies fail to provide a cohesive diagnosis needed for treatment. While there have been modifications in surgical procedures for lung biopsy that minimize postoperative morbidity, it remains a high-risk invasive procedure, especially in a medically complex patient(5). Thus, it is essential that the lung biopsy be handled properly to maximize diagnostic yield, including close communication between the clinician, radiologist, surgeon, and pathologist before biopsy to determine best sampling site(s) and prioritization of tissue utilization. This review provides an overview of optimal handling and evaluation of a surgical lung biopsy for suspected chILD, with emphasis on specific conditions in which pathologic features play a critical role in providing an integrated diagnosis and guiding management.

Bacillus megaterium infection presenting as pulmonary alveolar proteinosis, a case report

BACKGROUND

Pulmonary alveolar proteinosis (PAP) is a special clinical presentation mostly associated with autoimmune disorders. Here we report a rare case of PAP secondary to infection of Bacillus megaterium.

CASE PRESENTATION

A 58-year-old woman presented with intermittent cough and dyspnea for half a year. Chest CT scan showed "crazy paving" pattern. B. megaterium was identified by percutaneous CT-guided needle biopsy. She continuously received antimicrobial treatment since the diagnosis and follow-up examination suggested great improvement.

CONCLUSIONS

To our knowledge, this is the first case of B. megaterium infection presented with PAP pattern in healthy individuals. Attention should be paid on the secondary causes including rare pathogen infection when patients presented with PAP syndrome.

Autoantibodies Neutralizing GM-CSF in HIV-Negative Colombian Patients Infected with Cryptococcus gattii and C. neoformans

BACKGROUND

Cryptococcosis is a life-threatening disease caused by Cryptococcus neoformans or C. gattii. Neutralizing autoantibodies (auto-Abs) against granulocyte-macrophage colony-stimulating factor (GM-CSF) in otherwise healthy adults with cryptococcal meningitis have been described since 2013. We searched for neutralizing auto-Abs in sera collected from Colombian patients with non-HIV-associated cryptococcosis in a retrospective national cohort from 1997 to 2016.

METHODS

We reviewed clinical and laboratory records and assessed the presence of neutralizing auto-Abs against GM-CSF in 30 HIV negative adults with cryptococcosis (13 caused by C. gattii and 17 caused by C. neoformans).

RESULTS

We detected neutralizing auto-Abs against GM-CSF in the sera of 10 out of 13 (77%) patients infected with C. gattii and one out of 17 (6%) patients infected with C. neoformans.

CONCLUSIONS

We report eleven Colombian patients diagnosed with cryptococcosis who had auto-Abs that neutralize GM-CSF. Among these patients, ten were infected with C. gattii and only one with C. neoformans.

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.

Cytokine profiles associated with disease severity and prognosis of autoimmune pulmonary alveolar proteinosis

BACKGROUND

Pulmonary alveolar proteinosis (PAP) is characterized by an abnormal accumulation of surfactants in the alveoli. Most cases are classified as autoimmune PAP (APAP) because they are associated with autoantibodies against granulocyte-macrophage colony-stimulating factor (GM-CSF). However, GM-CSF autoantibody levels are unlikely to correlate with the disease severity or prognosis of APAP.

METHODS

We collected clinical records and measured 38 serum cytokine concentrations for consecutive patients with APAP. After exclusion of 21 cytokines because of undetectable levels, 17 cytokine levels were compared between low and high disease severity scores (DSSs). We also compared whole lung lavage (WLL)-free survival with cut-off values defined by receiver operating characteristic (ROC) curves of cytokine levels and WLL administration at 11 months.

RESULTS

Nineteen patients with APAP were enrolled in the study. Five were classified as DSS 1 or 2, while the others were classified as DSS 4 or 5. Comparison between DSS 1-2 and 4-5 revealed that the concentrations of IP-10 and GRO increased in the latter groups (p < 0.05). Fifteen patients underwent WLL. Comparison between those who underwent WLL within 11 months and the others showed that IP-10 and TNF-α were tended to be elevated in the former group (p = 0.082 and 0.057, respectively). The cut-off values of IP-10, 308.8 pg/mL and TNF-α, 19.1 pg/mL, defined by the ROC curves, significantly separated WLL-free survivals with log-rank analyses (p = 0.005).

CONCLUSIONS

The concentrations of IP-10 and GRO may reflect the DSSs of APAP. A combination of IP-10 and TNF-α levels could be a biomarker to predict WLL-free survival.

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.

A toxicology study of Csf2ra complementation and pulmonary macrophage transplantation therapy of hereditary PAP in mice

Pulmonary macrophage transplantation (PMT) is a gene and cell transplantation approach in development as therapy for hereditary pulmonary alveolar proteinosis (hPAP), a surfactant accumulation disorder caused by mutations in CSF2RA/B (and murine homologs). We conducted a toxicology study of PMT of Csf2ra gene-corrected macrophages (mGM-Rα+Mϕs) or saline-control intervention in Csf2raKO or wild-type (WT) mice including single ascending dose and repeat ascending dose studies evaluating safety, tolerability, pharmacokinetics, and pharmacodynamics. Lentiviral-mediated Csf2ra cDNA transfer restored GM-CSF signaling in mGM-Rα+Mϕs. Following PMT, mGM-Rα+Mϕs engrafted, remained within the lungs, and did not undergo uncontrolled proliferation or result in bronchospasm, pulmonary function abnormalities, pulmonary or systemic inflammation, anti-transgene product antibodies, or pulmonary fibrosis. Aggressive male fighting caused a similarly low rate of serious adverse events in saline- and PMT-treated mice. Transient, minor pulmonary neutrophilia and exacerbation of pre-existing hPAP-related lymphocytosis were observed 14 days after PMT of the safety margin dose but not the target dose (5,000,000 or 500,000 mGM-Rα+Mϕs, respectively) and only in Csf2raKO mice but not in WT mice. PMT reduced lung disease severity in Csf2raKO mice. Results indicate PMT of mGM-Rα+Mϕs was safe, well tolerated, and therapeutically efficacious in Csf2raKO mice, and established a no adverse effect level and 10-fold safety margin.