Expression data from brain, liver and spleen of Npc1-/- mice

Niemann-Pick Type C (NPC) disease is a rare, genetic, lysosomal disorder with progressive neurodegeneration. Poor understanding of the pathophysiology and lack of blood-based diagnostic markers are major hurdles in the treatment and management of NPC and several additional neurological, lysosomal disorders. To identify disease severity correlates, we undertook whole genome expression profiling of sentinel organs, brain, liver, and spleen of Balb/c Npc1-/- mice (Npc1nih)relative to Npc1+/- at an asymptomatic stage, as well as early- and late-symptomatic stages. Unexpectedly, we found prominent up regulation of innate immunity genes with age-dependent change in their expression, in all three organs. We shortlisted a set of 12 secretory genes whose expression steadily increased with age in both brain and liver, as potential plasma correlates for the neurological disease. Ten were innate immune genes with eight ascribed to lysosomes. Several are known to be elevated in diseased organs of murine models of other lysosomal diseases including Gauchers disease, Sandhoff disease and MPSIIIB. We validated the top candidate lysozyme, in the plasma of Npc1-/- as well as Balb/c Npc1nmf164 mice (bearing a point mutation closer to human disease mutants) and show its reduction in response to an emerging therapeutic. We further established elevation of innate immunity in Npc1-/- mice through multiple functional assays including inhibition of bacterial infection as well as cellular analysis and immunohistochemistry.

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Alam MS, Getz M, Safeukui I, Yi S, Tamez P, Shin J, Velázquez P, Haldar K