title: Altered Clathrin-Independent Endocytosis in Type A Niemann-Pick Disease Cells and Rescue by ICAM-1-Targeted Enzyme Delivery.
abstract: Pharmaceutical intervention often requires therapeutics and/or their carriers to enter cells via endocytosis. Therefore, endocytic aberrancies resulting from disease represent a key, yet often overlooked, parameter in designing therapeutic strategies. In the case of lysosomal storage diseases (LSDs), characterized by lysosomal accumulation of undegraded substances, common clinical interventions rely on endocytosis of recombinant enzymes. However, the lysosomal defect in these diseases can affect endocytosis, as we recently demonstrated for clathrin-mediated uptake in patient fibroblasts with type A Niemann-Pick disease (NPD), a disorder characterized by acid sphingomylinase (ASM) deficiency and subsequent sphingomyelin storage. Using similar cells, we have examined if this is also the case for clathrin-independent pathways, including caveolae-mediated endocytosis and macropinocytosis. We observed impaired caveolin-1 enrichment at ligand-binding sites in NPD relative to wild type fibroblasts, corresponding with altered uptake of ligands and fluid-phase markers by both pathways. Similarly, aberrant lysosomal storage of sphingomyelin induced by pharmacological means also diminished uptake. Partial degradation of the lysosomal storage by untargeted recombinant ASM led to partial uptake enhancement, whereas both parameters were restored to wild type levels by ASM delivery using model polymer nanocarriers specifically targeted to intercellular adhesion molecule-1. Carriers also restored caveolin-1 enrichment at ligand-binding sites and uptake through the caveolar and macropinocytic routes. These results demonstrate a link between lysosomal storage in NPD and alterations in clathrin-independent endocytosis, which could apply to other LSDs. Hence, this study shall guide the design of therapeutic approaches using viable endocytic pathways.
authors: †Fischell Department of Bioengineering, University of Maryland, College Park, Maryland 20742-4450, United States.
authors: Jeff
authors: J
authors: Rappaport
authors: †Fischell Department of Bioengineering, University of Maryland, College Park, Maryland 20742-4450, United States.
authors: Rachel L
authors: RL
authors: Manthe
authors: ‡Department of Normal and Pathological Histology and Cytology, University of Seville School of Medicine, Seville 41009, Spain.
authors: Carmen
authors: C
authors: Garnacho
authors: †Fischell Department of Bioengineering, University of Maryland, College Park, Maryland 20742-4450, United States.|§Institute for Bioscience and Biotechnology Research, University of Maryland, 5115 Plant Sciences Building, College Park, Maryland 20742-4450, United States.
authors: Silvia
authors: S
authors: Muro
mesh_terms: D051242:Caveolin 1 / Q000378:metabolism*; D002478:Cells, Cultured; D004705:Endocytosis / Q000502:physiology*; D006801:Humans; D018799:Intercellular Adhesion Molecule-1 / Q000378:metabolism*; D016464:Lysosomal Storage Diseases / Q000378:metabolism; D008856:Microscopy, Fluorescence; D052536:Niemann-Pick Disease, Type A / Q000378:metabolism*
chemical_list: D051242:Caveolin 1; D018799:Intercellular Adhesion Molecule-1
keywords: ICAM-1-targeted nanocarriers; caveolae-mediated endocytosis; enzyme delivery; lysosomal storage disorders; macropinocytosis; type A Niemann-Pick disease