Chinatsu Kaneko

Characteristics of a Large Cohort of Patients with Autoimmune Pulmonary Alveolar Proteinosis in Japan

RATIONALE Acquired pulmonary alveolar proteinosis (PAP) is a syndrome characterized by pulmonary surfactant accumulation occurring in association with granulocyte/macrophage colony-stimulating factor autoantibodies (autoimmune PAP) or as a consequence of another disease (secondary PAP). Because PAP is rare, prior reports were based on limited patient numbers or a synthesis of historical data. OBJECTIVES To describe the epidemiologic, clinical, physiologic, and laboratory features of autoimmune PAP in a large, contemporaneous cohort of patients with PAP. METHODS Over 6 years, 248 patients with PAP were enrolled in a Japanese national registry, including 223 with autoimmune PAP. MEASUREMENTS AND MAIN RESULTS Autoimmune PAP represented 89.9% of cases and had a minimum incidence and prevalence of 0.49 and 6.2 per million, respectively. The male to female ratio was 2.1:1, and the median age at diagnosis was 51 years. A history of smoking occurred in 56%, and dust exposure occurred in 23%; instances of familial onset did not occur. Dyspnea was the most common presenting symptom, occurring in 54.3%. Importantly, 31.8% of patients were asymptomatic and were identified by health screening. Intercurrent illnesses, including infections, were infrequent. A disease severity score reflecting the presence of symptoms and degree of hypoxemia correlated well with carbon monoxide diffusing capacity and serum biomarkers, less well with pulmonary function, and not with granulocyte/macrophage colony-stimulating factor autoantibody levels or duration of disease. CONCLUSIONS Autoimmune PAP had an incidence and prevalence higher than previously reported and was not strongly linked to smoking, occupational exposure, or other illnesses. The disease severity score and biomarkers provide novel and potentially useful outcome measures in PAP.

Inhaled granulocyte/macrophage-colony stimulating factor as therapy for pulmonary alveolar proteinosis.

RATIONALE Inhaled granulocyte/macrophage-colony stimulating factor (GM-CSF) is a promising therapy for pulmonary alveolar proteinosis (PAP) but has not been adequately studied. OBJECTIVES To evaluate safety and efficacy of inhaled GM-CSF in patients with unremitting or progressive PAP. METHODS We conducted a national, multicenter, self-controlled, phase II trial at nine pulmonary centers throughout Japan. Patients who had lung biopsy or cytology findings diagnostic of PAP, an elevated serum GM-CSF antibody level, and a Pa(O(2)) of less than 75 mm Hg entered a 12-week observation period. Those who improved (i.e., alveolar-arterial oxygen difference [A-aDO(2)] decreased by 10 mm Hg) during observation were excluded. The rest entered sequential periods of high-dose therapy (250 microg Days 1-8, none Days 9-14; x six cycles; 12 wk); low-dose therapy (125 microg Days 1-4, none Days 5-14; x six cycles; 12 wk), and follow-up (52 wk). MEASUREMENTS AND MAIN RESULTS Fifty patients with PAP were enrolled in the study. During observation, nine improved and two withdrew; all of these were excluded. Of 35 patients completing the high- and low-dose therapy, 24 improved, resulting in an overall response rate of 62% (24/39; intention-to-treat analysis) and reduction in A-aDO(2) of 12.3 mm Hg (95% confidence interval, 8.4-16.2; n = 35, P < 0.001). No serious adverse events occurred, and serum GM-CSF autoantibody levels were unchanged. A treatment-emergent correlation occurred between A-aDO(2) and diffusing capacity of the lung, and high-resolution CT revealed improvement of ground-glass opacity. Twenty-nine of 35 patients remained stable without further therapy for 1 year. CONCLUSIONS Inhaled GM-CSF therapy is safe, effective, and provides a sustained therapeutic effect in autoimmune PAP. Clinical trial registered with www.controlled-trials.com/isrctn (ISRCTN18931678), www.jmacct.med.or.jp/english (JMA-IIA00013).

Adult-onset hereditary pulmonary alveolar proteinosis caused by a single-base deletion in CSF2RB

Background Disruption of granulocyte/macrophage colony-stimulating factor (GM-CSF) signalling causes pulmonary alveolar proteinosis (PAP). Rarely, genetic defects in neonatal or infant-onset PAP have been identified in CSF2RA. However, no report has clearly identified any function-associated genetic defect in CSF2RB. Methods and results The patient was diagnosed with PAP at the age of 36 and developed respiratory failure. She was negative for GM-CSF autoantibody and had no underlying disease. Signalling and genetic defects in GM-CSF receptor were screened. GM-CSF-stimulated STAT5 phosphorylation was not observed and GM-CSF-Rβc expression was defective in the patients blood cells. Genetic screening revealed a homozygous, single-base deletion at nt 631 in exon 6 of CSF2RB on chromosome 22, which caused reductions in GM-CSF dependent signalling and function. Both parents, who were second cousins, showed no pulmonary symptoms, and had normal GM-CSF-signalling, but had a CSF2RB allele with the identical deletion, indicating that the mutant allele may give rise to PAP in an autosomal recessive manner. Conclusions This is the first report identifying a genetic defect in CSF2RB that causes deficiency of GM-CSF-Rβc expression and impaired signalling downstream. These results suggested that GM-CSF signalling was compensated by other signalling pathways, leading to adult-onset PAP.

Clinical features of secondary pulmonary alveolar proteinosis: pre-mortem cases in Japan

To the Editors: Pulmonary alveolar proteinosis (PAP) is a rare syndrome that predominantly affects the lungs, and is characterised by the accumulation of surfactant lipids and proteins in the alveoli and terminal airways 1. In 1999, we published findings that high levels of granulocyte-macrophage colony-stimulating factor (GM-CSF) neutralising autoantibodies were detected specifically in patients with idiopathic PAP 2. Recently, as a result of the excellent sensitivity and specificity of GM-CSF autoantibody assays in identifying this form of PAP 3, it has been proposed that the nomenclature for this condition should be changed to “autoimmune PAP” rather than “idiopathic PAP” 4. Secondary or hereditary PAP is not associated with GM-CSF autoantibodies but develops as a consequence of a separate underlying disorder or genetic background 5. Recently, we demonstrated that the characteristic high-resolution computed tomography (HRCT) findings in secondary PAP are distinct from those in autoimmune PAP 6. However, physicians may not suspect secondary PAP, even when encountering unexplained pulmonary opacities on chest radiograph or computed tomography in patients with pre-existing haematological or infectious diseases, since there is little information available on the clinical features. Here, we outline the clinical features of adult-onset secondary PAP based on our database of 40 pre-mortem cases in which serum GM-CSF autoantibodies were negative, and compare them with other cases in the literature. A total of 404 patients with pre-mortem cytologically or pathologically proven PAP were registered in our study group between 1999 and 2009. We obtained consent from all treating physicians for each identified case according to the guidelines for epidemiological studies from the Ministry of Health, Labour and Welfare 7, and all clinical data were de-identified. 360 (89%) cases were positive for serum GM-CSF autoantibody. The clinical features of 223 of the cases were previously published as …

Direct evidence that GM-CSF inhalation improves lung clearance in pulmonary alveolar proteinosis

BACKGROUND Autoimmune pulmonary alveolar proteinosis (aPAP) is caused by granulocyte/macrophage-colony stimulating factor (GM-CSF) autoantibodies in the lung. Previously, we reported that GM-CSF inhalation therapy improved alveolar-arterial oxygen difference and serum biomarkers of disease severity in these patients. It is plausible that inhaled GM-CSF improves the dysfunction of alveolar macrophages and promotes the clearance of the surfactant. However, effect of the therapy on components in bronchoalveolar lavage fluid (BALF) remains unclear. OBJECTIVES To figure out changes in surfactant clearance during GM-CSF inhalation therapy. METHODS We performed retrospective analyses of BALF obtained under a standardized protocol from the same bronchus in each of 19 aPAP patients before and after GM-CSF inhalation therapy (ISRCTN18931678, JMA-IIA00013; total dose 10.5-21 mg, duration 12-24 weeks). For evaluation, the participants were divided into two groups, high responders with improvement in alveolar-arterial oxygen difference ≥13 mmHg (n = 10) and low responders with that < 13 mmHg (n = 9). RESULTS Counts of both total cells and alveolar macrophages in BALF did not increase during the therapy. However, total protein and surfactant protein-A (SP-A) were significantly decreased in high responders, but not in low responders, suggesting that clearance of surfactant materials is correlated with the efficacy of the therapy. Among 94 biomarkers screened in bronchoalveolar lavage fluid, we found that the concentration of interleukin-17 and cancer antigen-125 were significantly increased after GM-CSF inhalation treatment. CONCLUSIONS GM-CSF inhalation decreased the concentration of total protein and SP-A in BALF, and increase interleukin-17 and cancer antigen-125 in improved lung of autoimmune pulmonary alveolar proteinosis.

IgM-type GM-CSF autoantibody is etiologically a bystander but associated with IgG-type autoantibody production in autoimmune pulmonary alveolar proteinosis

The granulocyte-macrophage colony-stimulating factor (GM-CSF) autoantibody (GMAb) is the causative agent underlying autoimmune pulmonary alveolar proteinosis (aPAP). It consists primarily of the IgG isotype. At present, information on other isotypes of the autoantibody is limited. We detected serum the IgM isotype of GMAb (IgM-GMAb) in more than 80% of patients with aPAP and 22% of healthy subjects, suggesting that a continuous antigen pressure may be present in most patients. Levels of the IgM isotype were weakly correlated with IgG-GMAb levels but not IgA-GMAb, suggesting that its production may be associated with that of IgG-GMAb. The mean binding avidity to GM-CSF of the IgM isotype was 100-fold lower than the IgG-GMAb isotype, whereas the IC(50) value for neutralizing capacity was 20,000-fold higher than that of IgG-GMAb, indicating that IgM-GMAb is only a very weak neutralizer of GM-CSF. In bronchoalveolar lavage fluid from nine patients, IgG-GMAb was consistently detected, but IgM-GMAb was under the detection limit in most patients, confirming that IgM-GMAb is functionally a bystander in the pathogenesis of aPAP. It rather may be involved in the mechanism for development of IgG-GMAb in vivo.

A cell-free assay to estimate the neutralizing capacity of granulocyte–macrophage colony-stimulating factor autoantibodies

The aim of the project is to develop a novel method estimating granulocyte-macrophage colony-stimulating factor (GM-CSF) neutralizing capacity with high-throughput and good reproducibility. For that purpose, we designed a cell-free receptor binding assay consisting of a solid-phase recombinant soluble GM-CSF receptor alpha (GMRalpha) and a biotinylated GM-CSF (bGM-CSF). Using this system, competitive inhibition of bGM-CSF binding to soluble GM-CSF receptor alpha (sGMRalpha) by GM-CSF autoantibody or IgG fractions from the sera of patients with pulmonary alveolar proteinosis was examined, resulting in excellent reproducibility. Binding inhibition was correlated with growth inhibition of TF-1 cells, a GM-CSF dependent cell line. These results suggest that our cell-free system can be applied to estimate the neutralizing capacity of GM-CSF autoantibodies ex vivo.

Light chain (κ/λ) ratio of GM-CSF autoantibodies is associated with disease severity in autoimmune pulmonary alveolar proteinosis☆☆

Previous studies demonstrated that antigranulocyte colony-stimulating factor autoantibody (GMAb) was consistently present in patients with autoimmune pulmonary alveolar proteinosis (aPAP), and, thus, represented candidature as a reliable diagnostic marker. However, our large cohort study suggested that the concentration of this antibody was not correlated with disease severity in patients. We found that the κ/λ ratio of GMAb was significantly correlated with the degree of hypoxemia. The proportion of λ-type GMAb per total λ-type IgG was significantly higher in severely affected patients than those in mildly affected patients, but the proportion of κ-type was unchanged. The κ/λ ratio was significantly correlated with both KL-6 and SP-D, which have been previously reported as disease severity markers. Thus, the light chain isotype usage of GMAb may not only be associated with the severity of aPAP, but may also represent a useful disease severity marker.