Cathepsin H and napsin A are active in the alveoli and increased in alveolar proteinosis.

Pulmonary alveolar proteinosis (PAP) is a group of rare diseases with disturbed homeostasis of alveolar surfactant. While 90% of the primary adult forms are caused by granulocyte-macrophage colony-stimulating factor autoantibodies, the underlying cause of the juvenile form remains unknown. In order to distinguish primary from secondary effects in the pathogenesis of these two forms, the present authors studied the surfactant protein processing proteases napsin A and cathepsin H. In total, 16 controls, 20 patients with juvenile PAP and 13 adults with idiopathic PAP were enrolled. Amounts and activities of the proteases in the bronchoalveolar lavage fluid (BALF) were determined by immunoblotting and specific substrate cleavage. Both proteases were present and active in BALF from controls and increased in juvenile and adult PAP patients. The amount of active cathepsin H in relation to total cathepsin H was increased in PAP patients compared with controls. Cystatin C, the physiological inhibitor of cathepsin H in the alveolar space, was not increased to the same degree as cathepsin H, resulting in an imbalance of inhibitor to protease in the alveolar space. A general defect in napsin A or cathepsin H expression or activity was not the specific cause for abnormal surfactant accumulation in juvenile pulmonary alveolar proteinosis.

[Off-line exhaled nitric oxide measurement in children]. / Mesure de la fraction expirée de NO chez l'enfant par une analyse extemporanée.

INTRODUCTION: The objective is to test the validity of a tool allowing an offline measurement of the fraction of expired nitric oxide (FENO). The device is a T-tube on which a pressure gauge allows the control of the expiratory flow and whose two side branches have a gauge such as the bags assembled on each one of them fill successively. METHODS: The first phase aims to check that the sample collected in the second bag answers the criteria of analysis of NO during a single expiration and that this measurement can be delayed. The second phase aims to test the feasibility and the repeatability of the offline analysis in children. RESULTS: The device makes it possible to stabilize the expiratory flow at 100 ml/s. The NO concentration in the second bag is stable during 6 hours. The intra measurement coefficient of variation of delayed FENO 0.1 is 7% (N = 19). CONCLUSION: A off line measurement of the exhaled nitric oxide is reliable in asthmatic children.