OBJECTIVE: Anti-granulocyte-macrophage colony-stimulating factor autoantibodies (anti-GM-CSF Abs) are implicated in the pathogenesis of Cryptococcus gattii (C. gattii) infection and pulmonary alveolar proteinosis (PAP). Their presence has also been noted in nocardiosis cases, particularly those with disseminated disease. This study delineates a case series characterizing clinical features and specificity of anti-GM-CSF Abs in nocardiosis patients.
METHODS: In this study, eight patients were recruited to determine the presence or absence of anti-GM-CSF Abs. In addition to the detailed description of the clinical course, we thoroughly investigated the autoantibodies regarding the characteristics, isotypes, subclasses, titers, and neutralizing capacities by utilizing the plasma samples from patients.
RESULTS: Of eight patients, five tested positive for anti-GM-CSF Abs, all with central nervous system (CNS) involvement; patients negative for these antibodies did not develop CNS nocardiosis. Distinct from previously documented cases, none of our patients with anti-GM-CSF Abs exhibited PAP symptoms. The titer and neutralizing activity of anti-GM-CSF Abs in our cohort did not significantly deviate from those found in C. gattii cryptococcosis and PAP patients. Uniquely, one individual (Patient 3) showed a minimal titer and neutralizing action of anti-GM-CSF Abs, with no relation to disease severity. Moreover, IgM autoantibodies were notably present in all CNS nocardiosis cases investigated.
CONCLUSIONS: The presence of anti-GM-CSF Abs suggests an intrinsic immunodeficiency predisposing individuals toward CNS nocardiosis. The presence of anti-GM-CSF Abs helps to elucidate vulnerability to CNS nocardiosis, even with low titer of autoantibodies. Consequently, systematic screening for anti-GM-CSF Abs should be considered a crucial diagnostic step for nocardiosis patients.

UNASSIGNED: Lysinuric protein intolerance (LPI) is a rare genetic disorder caused by mutations in the solute carrier family 7A member 7 (SLC7A7) gene.
UNASSIGNED: We presented two siblings with LPI, carrying novel mutations of c.776delT (p.L259Rfs*18) and c.155G>T (p.G52V) in SLC7A7. The younger sibling, preferring protein-rich foods, showed severe symptoms, including alveolar proteinosis, macrophage activation syndrome, severe diarrhea, and disturbance of consciousness with involuntary movements. In contrast, the elder sibling only had mild symptoms, likely due to aversion to protein-rich food since toddler age.
UNASSIGNED: LPI is a congenital genetic metabolic disease with multi-system involvement. Initiating appropriate protein-restricted diet therapy as soon as possible could help prevent the progression of LPI.

BACKGROUND: Pulmonary alveolar proteinosis (PAP) and X-linked agammaglobulinemia (XLA) are rare diseases in children. Many theories infer that immunodeficiency can induce PAP, but these reports are almost all review articles, and there is little clinical evidence. We report the case of a child with both PAP and XLA.
METHODS: A 4-month-old boy sought medical treatment due to coughing and difficulty in breathing for > 2 wk. He had been hospitalized multiple times due to respiratory infections and diarrhea. Chest computed tomography and alveolar lavage fluid showed typical PAP-related manifestations. Genetic testing confirmed that the boy also had XLA. Following total lung alveolar lavage and intravenous immunoglobulin replacement therapy, the boy recovered and was discharged. During the follow-up period, the number of respiratory infections was significantly reduced, and PAP did not recur.
CONCLUSIONS: XLA can induce PAP and improving immune function contributes to the prognosis of children with this type of PAP.

BACKGROUND: Congenital surfactant deficiency, often caused by mutations in genes involved in surfactant biosynthesis such as ABCA3, presents a significant challenge in neonatal care due to its severe respiratory manifestations. This study aims to analyze the clinical data of a newborn male diagnosed with pulmonary surfactant metabolism dysfunction type 3 resulting from ABCA3 gene mutations to provide insights into the management of this condition.
METHODS: A newly born male child aged 1 day and 3 hours was referred to our department due to poor crying and shortness of breath.
METHODS: Primary diagnoses by the duty physicians were: neonatal pneumonia, neonatal respiratory failure, persistent neonatal pulmonary hypertension, birth asphyxia, myocardial damage, and arteriovenous catheterization. Genetic test revealed a compound heterozygous variant in the ABCA3 gene. One allele may be exon variant c.4561C>T, the second allele may be intron variant c.1896 + 2_1896 + 17del. The associated disease included pulmonary surfactant metabolism dysfunction type 3.
METHODS: He was initially treated with an antiinfective therapeutic regimen.
RESULTS: The family was informed of this condition and signed off, and the child died.
CONCLUSIONS: Hereditary pulmonary surfactant deficiency is a rare and untreatable disease. The case highlights the challenges in managing congenital surfactant deficiencies and emphasizes the need for heightened awareness of this rare cause of infant respiratory failure.

A 50-year-old male was admitted to the hospital with a 3-year history of dyspnea and cough. Chest high-resolution computed tomography (HRCT) did not show typical features of pulmonary alveolar proteinosis (PAP), but rather atypical features of interstitial lung disease with fibrosis. The diagnosis of PAP was confirmed through transbronchial lung cryobiopsy. Whole exome sequencing identified a rare homozygous frame shift mutation (c.304_305del:p.S102Ffs*5) in exon 3 of the CSF2RB gene in our patient. This case represents a rare occurrence of fibrotic interstitial lung disease in PAP.

The diagnosis of pulmonary alveolar proteinosis (PAP) is based on biopsies. Compared with other methods of taking biopsies, transbronchial lung cryobiopsy (TBLC) has a higher diagnostic rate and the likelihood of pneumothorax. Selective bronchial occlusion (SBO) is an effective technique for treating intractable pneumothorax. However, there are no data available about SBO for the prevention of pneumothorax after TBLC in a PAP patient. A 49-year-old man complained of recurrent cough and tachypnea, and his symptoms did not fully resolve until the diagnosis was confirmed, and he was treated with whole lung lavage. Our patient was ultimately diagnosed with PAP by TBLC but not multiple tests for the bronchoalveolar lavage fluid (BALF). The patient was discharged quickly after whole lung lavage due to the fact that he did not develop pneumothorax under SBO. This case illustrates that TBLC is a supplementary examination for PAP, especially for those in whom BALF results fail to confirm a diagnosis. Moreover, our report highlights that SBO is necessary to effectively prevent pneumothorax during and after multiple TBLCs in PAP patients.

Pulmonary alveolar proteinosis (PAP) is a rare interstitial lung disease characterised by the accumulation of lipoprotein material in the alveoli. Although dyslipidaemia is a prominet feature, the causal effect of lipid traits on PAP remains unclear. This study aimed to explore the role of lipid traits in PAP and evaluate the potential of lipid-lowering drug targets in PAP.
Clinical outcomes, lipid profiles and lung function tests were analysed in a clinical cohort of diagnosed PAP patients and propensity score-matched healthy controls. Genome-wide association study data on PAP, lipid metabolism, blood cells and variants of genes encoding potential lipid-lowering drug targets were obtained for Mendelian randomisation (MR) and mediation analyses.
Observational results showed that higher levels of total cholesterol (TC), triglycerides and low-density lipoprotein (LDL) were associated with increased risks of PAP. Higher levels of TC and LDL were also associated with worse PAP severity. In MR analysis, elevated LDL was associated with an increased risk of PAP (OR: 4.32, 95% CI: 1.63 to 11.61, p=0.018). Elevated monocytes were associated with a lower risk of PAP (OR 0.34, 95% CI: 0.18 to 0.66, p=0.002) and mediated the risk impact of LDL on PAP. Genetic mimicry of PCSK9 inhibition was associated with a reduced risk of PAP (OR 0.03, p=0.007).
Our results support the crucial role of lipid and metabolism-related traits in PAP risk, emphasising the monocyte-mediated, causal effect of elevated LDL in PAP genetics. PCSK9 mediates the development of PAP by raising LDL. These finding provide evidence for lipid-related mechanisms and promising lipid-lowering drug target for PAP.

BACKGROUND: Pulmonary alveolar proteinosis (PAP) is a rare pulmonary disease characterized by abnormal accumulation of pulmonary surfactant lipids in alveoli or terminal bronchioles, leading to increased infection risk and progressive respiratory failure. Approximately more than 90% of all cases are autoimmune PAP (aPAP). Since one of the predisposing factors has been identified as genes located within the major-histocompatibility-complex region, an investigation of human leukocyte antigen (HLA) alleles associated with the risk of aPAP is warranted.
METHODS: We retrospectively studied 60 patients pathologically diagnosed with PAP from 2019 to 2022. Patients were divided into the aPAP group or secondary PAP (sPAP) group according to their clinical information. Qualified DNA was extracted from the paraffin-embedded tissue of 28 patients, and the PCR-sequence-based typing method was used for HLA-DRB1 genotyping.
RESULTS: A similar HLA-DRB1 allele profile (including the HLA-DRB1*08:03) between the aPAP group and sPAP group was revealed, except that HLA-DRB1*14:54, which has never been reported in aPAP patients, was only detected in the aPAP group rather than the sPAP group (19.4% vs. 0.0%, p = 0.030). Under inhaled granulocyte-macrophage colony-stimulating factor therapy, more clinical remission was observed in HLA-DRB1*14:54 carriers rather than in HLA-DRB1*08:03 carriers (80.0% vs. 57.1%).
CONCLUSIONS: Our real-world study revealed for the first time that a population with HLA-DRB1*14:54 was subject to aPAP, and HLA-DRB1*14:54 might imply a response in aPAP patients to inhaled granulocyte-macrophage colony-stimulating factor in aPAP patients.

BACKGROUND: Autoimmune pulmonary alveolar proteinosis (aPAP) is a rare interstitial lung disease. COVID-19 is associated with worse prognosis in previous lung diseases patients. But the prognosis of aPAP patients after infection with COVID-19 is unclear. In December 2022, China experienced a large-scale outbreak of Omicron variant of the SARS-CoV-2. In this study, we aim to explore the clinical outcomes of aPAP patients infected with COVID-19.
RESULTS: A total of 39 aPAP patients were included in this study. 30.77% patients had a decrease in oxygen saturation after COVID-19 infection. We compared the two groups of patients with or without decreased oxygen saturation after COVID-19 infection and found that patients who had previous oxygen therapy (decreased oxygen saturation vs. non decreased oxygen saturation: 6/12 vs. 4/27, P = 0.043), with lower baseline arterial oxygen partial pressure (74.50 ± 13.61 mmHg vs. 86.49 ± 11.92 mmHg, P = 0.009), lower baseline DLCO/VA% [77.0 (74.3, 93.6) % vs. 89.5 (78.2, 97.4) %, P = 0.036], shorter baseline 6MWD [464 (406, 538) m vs. 532 (470, 575) m, P = 0.028], higher disease severity score (P = 0.017), were more likely to have decreased oxygen saturation after COVID-19 infection.
CONCLUSIONS: aPAP patients with poor baseline respiration have a higher probability of hypoxia after COVID-19 infection, but fatal events were rare.

The male patient was referred to the hospital at 44 days old due to dyspnea after birth and inability to wean off oxygen. His brother died three days after birth due to respiratory failure. The main symptoms observed were respiratory failure, dyspnea, and hypoxemia. A chest CT scan revealed characteristic reduced opacity in both lungs with a \"crazy-paving\" appearance. The bronchoalveolar lavage fluid (BALF) showed periodic acid-Schiff positive proteinaceous deposits. Genetic testing indicated a compound heterozygous mutation in the ABCA3 gene. The diagnosis for the infant was congenital pulmonary alveolar proteinosis (PAP). Congenital PAP is a significant cause of challenging-to-treat respiratory failure in full-term infants. Therefore, congenital PAP should be considered in infants experiencing persistently difficult-to-treat dyspnea shortly after birth. Early utilization of chest CT scans, BALF pathological examination, and genetic testing may aid in early diagnosis.
患儿，男，44日龄，因生后呼吸困难、不能离氧1月余入院。既往有一哥哥，生后3 d因呼吸衰竭夭折。患儿主要表现为生后不久出现呼吸衰竭、呼吸困难、低氧血症。胸部CT表现为双肺透亮度明显减低，呈“铺路石征”；支气管肺泡灌洗液病理检查免疫组化呈现过碘酸希夫染色阳性；基因检测结果提示ABCA3基因复合杂合突变。该患儿诊断为先天性肺泡蛋白沉积症。先天性肺泡蛋白沉积症是导致足月儿难以治疗的呼吸衰竭的重要原因，因此对生后较早起病的难治性呼吸困难需考虑该疾病可能，尽早行胸部CT检查、支气管肺泡灌洗液病理学检查及基因检测，有助于早期诊断及指导临床决策。.