[Therapeutic efficacy of GM-CSF in pulmonary alveolar proteinosis]

Effectiveness of granulocyte-macrophage colony-stimulating factor therapy in autoimmune pulmonary alveolar proteinosis: a meta-analysis of observational studies

BACKGROUND

Autoimmune pulmonary alveolar proteinosis (aPAP) is a rare pulmonary disease caused by functional deficiency of granulocyte-macrophage colony-stimulating factor (GM-CSF). Administration of GM-CSF represents a potential therapeutic strategy in management of aPAP. Herein, we systematically review the efficacy of GM-CSF therapy in aPAP.

METHODS

We searched the PubMed and EmBase databases for studies reporting the use of GM-CSF in aPAP. We calculated the proportion with 95% CI to assess the response and relapse rates of GM-CSF therapy in individual studies and pooled them using a random-effects model. Statistical heterogeneity was assessed using the I(2) and Cochran Q tests. Publication bias was analyzed using funnel plot and Egger and Begg-Mazumdar tests.

RESULTS

Our initial searches yielded 1,585 studies. Of these, five observational studies (involving 94 patients) were included for analysis. Three studies used the subcutaneous route, and two studies used the inhalational route for GM-CSF administration. The response rate of GM-CSF varied from 43% to 92%, with the pooled response rate being 58.6% (95% CI, 42.7-72.9). The relapse rate in GM-CSF responders was 29.7% (95% CI, 10.5-60.4). There was no evidence of statistical heterogeneity or publication bias for the outcome of response. GM-CSF therapy was associated with minor complications, such as fever and local complications at the site of administration.

CONCLUSIONS

GM-CSF represents a useful approach in the treatment of aPAP. The optimal indication, dose and duration of therapy, and the factors predicting response and relapse need to be defined by future studies.

Recurrent pulmonary alveolar proteinosis secondary to agammaglobulinemia

Pulmonary alveolar proteinosis (PAP) is characterized by the accumulation of surfactant derived material in the lung of patients. PAP is rare in children. The patient presented with respiratory failure. In the history she was diagnosed with agammaglobulinemia at 8 months of age and has been treated by IVIG once in a month. She had two pulmonary alveolary proteinosis attacks before. Chest X-ray showed bilateral diffuse infiltrates. Initial diagnosis were pneumonia, ARDS, and lung edema. Whole-lung lavage revealed lipoproteinaceous material similar to surfactant. This findings and high level of LDH was as evaluated pulmonary alveolary proteinosis. She discharged from the hospital without any respiratory complication on the ninth day. This is the first case report recurrent PAP associated with agammaglobulinemia.

Pulmonary alveolar proteinosis

Pulmonary alveolar proteinosis is a rare syndrome characterized by intra-alveolar accumulation of surfactant components and cellular debris, with minimal interstitial inflammation or fibrosis. The condition has a variable clinical course, from spontaneous resolution to respiratory failure and death due to disease progression or superimposed infections. The standard of care for alveolor proteinosis therapy is represented by whole lung lavage. Important discoveries have been made in the last decade with respect to disease pathogenesis and therapy of both congenital and acquired forms of the disease. Granulocyte-macrophage colony-stimulating factor (GM-CSF) pathway has been shown to be involved in the disease pathogenesis of both acquired and congenital disease. Furthermore, anti-GM-CSF blocking autoantibodies have been found in the serum and bronchoalveolar lavage fluid and seem to interfere with the surfactant clearance by alveolar macrophages in many acquired cases. In the congenital form, the most common defects identified to date are several mutations of the genes encoding GM-CSF receptor subunits or surfactant proteins. Using GM-CSF as a therapeutic tool has also been shown to be effective in at least half of the acquired cases treated, while the importance of quantitative determination of anti-GM-CSF antibodies before and during the course of the therapy, as well as the autoantibody titer-GM-CSF dose relationship are to be elucidated. The congenital form of the disease does not respond to therapy with GM-CSF, consistent with the known primary defects and differences in disease pathogenesis.

Pulmonary alveolar proteinosis

Pulmonary alveolar proteinosis (PAP) has been recognized for almost half a century. At least three separate pathophysiologic mechanisms may lead to the characteristic feature of PAP: the excessive accumulation of surfactant lipoprotein in pulmonary alveoli, with associated disturbance of pulmonary gas exchange. The prognosis for adult patients with PAP varies, but disease-specific survival rate exceeds 80% at 5 years. The survival rates for adult PAP patients seem to have increased progressively in the four decades since the initial clinical description of this condition. The last decade has brought new advances in laboratory and clinical research that are lifting a veil not only on PAP but also on general aspects of pulmonary surfactant biology and innate immune defense.