Biomarkers Of Lung InVolvement In ASMD

Rationale: Acid sphingomyelinase deficiency (ASMD) is a lysosomal storage disease in which sphingomyelin accumulates due to a deficiency of the enzyme acid sphingomyelinase. The most common manifestations of the chronic visceral subtype of this disease are hepatosplenomegaly and interstitial lung disease (ILD). Currently, enzyme replacement therapy is under investigation and will likely become available in the near future. The first results indicate that pulmonary involvement may be responsive to treatment. In order to identify those patients that will potentially benefit from therapy, biomarkers for lung injury can be helpful. Compounds measured in exhaled breath and exhaled breath condensate are extensively studied in common lung diseases and increasingly in ILD. These compounds are of interest since they provide information directly form the lung compartment and are collected non-invasively.

Objective: Our aim is to characterize ASMD patients' breath profile, exhaled breath and condensate as compared to healthy controls to identify specific volatile and non-volatile compounds that reflect inflammatory processes, fibrotic processes or sphingolipid accumulation in the lungs.

Study design: This study comprises a cross-sectional case-control part and a prospective cohort part. In the cross-sectional part, exhaled breath samples with volatile and non-volatile compounds of ASMD patients and healthy controls will be collected. After potential biomarkers are identified in the cross-sectional part, patients will enter the longitudinal part in which the prognostic and monitoring value of these markers will be evaluated using clinical parameters.

Study population: ASMD patients ≥ 12 years of age with a confirmed diagnosis of the chronic visceral type will be included as well as age-, sex- and smoking status-matched healthy controls with a ratio of 1:3.

Main study parameters/endpoints: Inflammatory markers, fibrotic markers and markers of sphingolipid accumulation will be measured in exhaled breath. Breath profiles will be measured with eNose, volatile compounds will be measured with GC-MS and non-volatile compounds will be measured in exhaled breath condensates using UPLC-MS/MS.