Defining lung pathogenesis in a murine model of mucopolysaccharidosis Type I by proteomic analysis

Mucopolysaccharidosis type I (MPS I) is a rare lysosomal storage disorder resulting from a deficiency in the lysosomal enzyme alpha-L-iduronidase, which degrades heparan sulfate and dermatan sulfate glycosaminoglycans (GAG) within endosome-lysosome compartments. MPS I patients demonstrate respiratory dysfunction with varying symptoms and severity during disease progression, which has been associated primarily with upper airway involvement and the thoracic cavity. However, the involvement of respiratory complications in patient morbidity and mortality suggests that we know relatively little about the pathogenic process in the lung. Using a proteomics approach, we analyzed lung tissues from a murine model of MPS I to identify proteins and molecular pathways contributing to respiratory pathology. A total of 7604 proteins were identified, of which 144 were significantly upregulated, 93 downregulated, and three proteins (GPNMB, SLC39A1, ABCC10) were uniquely detected in MPS I lung tissue compared to control lung tissue. Gene ontology analysis confirmed significant disruptions to lysosomal biogenesis, GAG degradation pathways, and extracellular matrix remodelling. Immunohistochemistry showed elevated LAMP I expression, which was consistent with the proteomic results and endosome-lysosome dysfunction being a key driver of disease pathogenesis in the MPS I lung. Our findings reveal novel proteomic alterations underlying distal lung pathology in MPS I and identify potential biomarkers that may have clinical utility for monitoring disease progression.