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Clinical significance of anti-GM-CSF antibodies in idiopathic pulmonary alveolar proteinosis.

ABSTRACT: BACKGROUND: The role of anti-granulocyte-macrophage colony stimulating factor (GM-CSF) antibodies as a diagnostic marker in idiopathic pulmonary alveolar proteinosis (iPAP) remains unclear. METHODS: Anti-GM-CSF antibodies were detected in blood and bronchoalveolar lavage fluid (BAL) fluid in 13 patients with iPAP. Three patients with secondary PAP, 35 with other pulmonary disorders, and 10 subjects without lung lesions acted as controls. Blood samples only were obtained from 30 healthy medical personnel. Anti-GM-CSF antibodies were detected using immunoblotting and measured semi-quantitatively by serial dilution or concentration methods. The relationship between antibodies and reported severity indicators for iPAP was analysed. RESULTS: Anti-GM-CSF antibodies could be detected in both blood and BAL fluid samples in 12 of 13 iPAP patients and were undetectable in blood and/or BAL fluid from the other subjects studied. BAL fluid levels of anti-GM-CSF antibodies were highly correlated with the severity indicators for iPAP, including serum lactate dehydrogenase (LDH) levels, arterial oxygen tension, alveolar-arterial oxygen tension difference, (AaPO2), lung carbon monoxide transfer factor, and some lesion scores on chest radiographs and computed tomographic scans. In contrast, blood anti-GM-CSF antibodies were not significantly correlated with the severity indicators evaluated. In addition, patients with iPAP who required subsequent therapeutic lung lavage had significantly higher values of serum LDH, AaPO2, and BAL fluid anti-GM-CSF antibodies, and significantly lower values of PaO2. CONCLUSIONS: In addition to serum LDH levels, PaO2 and AaPO2, BAL fluid levels of anti-GM-CSF antibodies might reflect disease severity in patients with iPAP and predict the need for subsequent therapeutic lung lavage. These findings may expand the role of anti-GM-CSF antibodies in iPAP.

SUBMITTER: Lin FC

PROVIDER: S-EPMC2111220 | biostudies-other | 2006 Jun

REPOSITORIES: biostudies-other

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Clinical significance of anti-GM-CSF antibodies in idiopathic pulmonary alveolar proteinosis.

Lin F-C FC Chang G-D GD Chern M-S MS Chen Y-C YC Chang S-C SC

Thorax 20060303 6

<h4>Background</h4>The role of anti-granulocyte-macrophage colony stimulating factor (GM-CSF) antibodies as a diagnostic marker in idiopathic pulmonary alveolar proteinosis (iPAP) remains unclear.<h4>Methods</h4>Anti-GM-CSF antibodies were detected in blood and bronchoalveolar lavage fluid (BAL) fluid in 13 patients with iPAP. Three patients with secondary PAP, 35 with other pulmonary disorders, and 10 subjects without lung lesions acted as controls. Blood samples only were obtained from 30 heal ...[more]

PMID: 16517574

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Project description:RationaleWhole lung lavage (WLL) is a widely accepted palliative treatment for autoimmune pulmonary alveolar proteinosis (aPAP) but does not correct myeloid cell dysfunction or reverse the pathological accumulation of surfactant. In contrast, inhaled recombinant granulocyte-macrophage colony-stimulating factor (rGM-CSF) is a promising pharmacological approach that restores alveolar macrophage functions including surfactant clearance. Here, we evaluate WLL followed by inhaled rGM-CSF (sargramostim) as therapy of aPAP.Methods18 patients with moderate-to-severe aPAP were enrolled, received baseline WLL, were randomised into either the rGM-CSF group (receiving inhaled sargramostim) or control group (no scheduled therapy) and followed for 30 months after the baseline WLL. Outcome measures included additional unscheduled "rescue" WLL for disease progression, assessment of arterial blood gases, pulmonary function, computed tomography, health status, biomarkers and adverse events. Patients requiring rescue WLL were considered to have failed their assigned intervention group.ResultsThe primary end-point of time to first rescue WLL was longer in rGM-CSF-treated patients than controls (30 versus 18 months, n=9 per group, p=0.0078). Seven control patients (78%) and only one rGM-CSF-treated patient (11%) required rescue WLL, demonstrating a 7-fold increase in relative risk (p=0.015). Compared to controls, rGM-CSF-treated patients also had greater improvement in peripheral arterial oxygen tension, alveolar-arterial oxygen tension difference, diffusing capacity of the lungs for carbon monoxide and aPAP biomarkers. One patient from each group withdrew for personal reasons. No serious adverse events were reported.ConclusionsThis long-term, prospective, randomised trial demonstrated inhaled sargramostim following WLL reduced the requirement for WLL, improved lung function and was safe in aPAP patients. WLL plus inhaled sargramostim may be useful as combined therapy for aPAP.

Project description:Pulmonary Alveolar Proteinosis (PAP) patients exhibit an acquired deficiency of biologically active granulocyte-macrophage colony stimulating factor (GM-CSF) attributable to GM-CSF specific autoantibodies. PAP alveolar macrophages are foamy, lipid-filled cells with impaired surfactant clearance and markedly reduced expression of the transcription factor peroxisome proliferator-activated receptor gamma (PPAR?) and the PPAR?-regulated ATP binding cassette (ABC) lipid transporter, ABCG1. An open label proof of concept Phase II clinical trial was conducted in PAP patients using rituximab, a chimeric murine-human monoclonal antibody directed against B lymphocyte specific antigen CD20. Rituximab treatment decreased anti-GM-CSF antibody levels in bronchoalveolar lavage (BAL) fluid, and 7/9 patients completing the trial demonstrated clinical improvement as measured by arterial blood oxygenation.This study sought to determine whether rituximab therapy would restore lipid metabolism in PAP alveolar macrophages.BAL samples were collected from patients pre- and 6-months post-rituximab infusion for evaluation of mRNA and lipid changes.Mean PPAR? and ABCG1 mRNA expression increased 2.8 and 5.3-fold respectively (p???0.05) after treatment. Lysosomal phospholipase A2 (LPLA2) (a key enzyme in surfactant degradation) mRNA expression was severely deficient in PAP patients pre-treatment but increased 2.8-fold post-treatment. In supplemental animal studies, LPLA2 deficiency was verified in GM-CSF KO mice but was not present in macrophage-specific PPAR? KO mice compared to wild-type controls. Oil Red O intensity of PAP alveolar macrophages decreased after treatment, indicating reduced intracellular lipid while extracellular free cholesterol increased in BAL fluid. Furthermore, total protein and Surfactant protein A were significantly decreased in the BAL fluid post therapy.Reduction in GM-CSF autoantibodies by rituximab therapy improves alveolar macrophage lipid metabolism by increasing lipid transport and surfactant catabolism. Mechanisms may involve GM-CSF stimulation of alveolar macrophage ABCG1 and LPLA2 activities by distinct pathways.

Project description:BackgroundAutoimmune pulmonary alveolar proteinosis (aPAP) is a rare disease characterized by progressive surfactant accumulation and hypoxemia. It is caused by disruption of granulocyte-macrophage colony-stimulating factor (GM-CSF) signaling, which pulmonary alveolar macrophages require to clear surfactant. Recently, inhaled GM-CSF was shown to improve the partial pressure of arterial oxygen in patients with aPAP.MethodsIn a double-blind, placebo-controlled, three-group trial, we randomly assigned patients with aPAP to receive the recombinant GM-CSF molgramostim (300 μg once daily by inhalation), either continuously or intermittently (every other week), or matching placebo. The 24-week intervention period was followed by an open-label treatment-extension period. The primary end point was the change from baseline in the alveolar-arterial difference in oxygen concentration (A-aDo2) at week 24.ResultsIn total, 138 patients underwent randomization; 46 were assigned to receive continuous molgramostim, 45 to receive intermittent molgramostim, and 47 to receive placebo. Invalid A-aDo2 data for 4 patients (1 in each molgramostim group and 2 in the placebo group) who received nasal oxygen therapy during arterial blood gas measurement were replaced by means of imputation. For the primary end point - the change from baseline in the A-aDo2 at week 24 - improvement was greater among patients receiving continuous molgramostim than among those receiving placebo (-12.8 mm Hg vs. -6.6 mm Hg; estimated treatment difference, -6.2 mm Hg; P = 0.03 by comparison of least-squares means). Patients receiving continuous molgramostim also had greater improvement than those receiving placebo for secondary end points, including the change from baseline in the St. George's Respiratory Questionnaire total score at week 24 (-12.4 points vs. -5.1 points; estimated treatment difference, -7.4 points; P = 0.01 by comparison of least-squares means). For multiple end points, improvement was greater with continuous molgramostim than with intermittent molgramostim. The percentages of patients with adverse events and serious adverse events were similar in the three groups, except for the percentage of patients with chest pain, which was higher in the continuous-molgramostim group.ConclusionsIn patients with aPAP, daily administration of inhaled molgramostim resulted in greater improvements in pulmonary gas transfer and functional health status than placebo, with similar rates of adverse events. (Funded by Savara Pharmaceuticals; IMPALA ClinicalTrials.gov number, NCT02702180.).

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Clinical significance of anti-GM-CSF antibodies in idiopathic pulmonary alveolar proteinosis.

Publications

Clinical significance of anti-GM-CSF antibodies in idiopathic pulmonary alveolar proteinosis.

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