Hepatic and neuronal phenotype of NPC1−/− mice

Abstract

Niemann-Pick type C disease (NPC) is a fatal autosomal recessive disorder characterized by a defect in the intracellular transport of lipoproteins leading to the accumulation of lipids in diverse tissues. A visceral and neuronal phenotype mimicking human NPC1 disease has been described in NPC1 mutant mice. These mice are by now the most widely used NPC1 rodent model to study NPC and developmental compounds against this devastating disease. Here we characterized NPC1−/− mice for their hepatic and neuronal phenotype to confirm the stability of the phenotype, provide a characterization of disease progression and pinpoint the age of robust phenotype onset. Animals of 4–10 weeks of age were analyzed for general health, motor deficits as well as hepatic and neuronal alterations with a special focus on cerebellar pathology.Our results show that NPC1−/− mice have a reduced general health at the age of 9–10 weeks. Robust motor deficits can be observed even earlier at 8 weeks of age. Hepatic changes included increased organ weight and cholesterol levels at 6 weeks of age accompanied by severely increased liver enzyme levels. Analysis of NPC1−/− brain pathology showed decreased cholesterol and increased Aβ levels in the hippocampus at the age of 6 weeks. Further analysis revealed a decrease of the cytokine IL-12p70 in the cerebellum along with a very early increase of astrocytosis. Hippocampal IL-12p70 levels were increased at the age of 6 weeks followed by increased activated microglia levels. By the age of 10 weeks, also cerebellar Aβ levels were increased along with strongly reduced Calbindin D-28k levels.Our results validate and summarize the progressive development of the hepatic and neuronal phenotype of NPC1−/− mice that starts with cerebellar astrocytosis, making this mouse model a valuable tool for the development of new compounds against NPC.

Evaluation of the Potential Role of Proprotein Convertase Subtilisin/Kexin Type 9 (PCSK9) in Niemann–Pick Disease, Type C1

“…We measured the activity of three liver enzymes, alkaline phosphatase (AP), alanine aminotransferase (ALT) and aspartate aminotransferase (AST), in the serum and showed significantly elevated levels in Npc1 mutant mice (Npc1 -/-/Pcsk9 -/-(n = 9) or Npc1 -/-/Pcsk9 +/+ (n = 6)), compared to the control groups (Npc1 +/+ /Pcsk9 +/+ (n = 4) or Npc1 +/+ /Pcsk9 -/-(n = 8)), which were within the normal range ( Figure 5). The elevated values in Npc1 -/mice are consistent with values published previously for Npc1 -/mice on a Balbc background [45]. Levels of ALT were reduced in the Npc1 -/-/Pcsk9 -/mice compared to Npc1 -/-/Pcsk9 +/+ (p = 0.031) ( Figure 5B), whereas AP and AST were not significantly different ( Figure 5A,C) suggesting that the diseased liver function in Npc1 -/-/Pcsk9 -/mice was equivalent to or even less than the Npc1 -/-/Pcsk9 +/+ mice at this age.…”

“…No obvious differences were seen between the Pcsk9 +/+ and Pcsk9 +/mice and these data were combined as Pcsk9 ctrl . Single knockout Npc1 -/-/Pcsk9 ctrl male (n = 10) and female (n = 14) mice had an initial normal, but slightly reduced, weight-gain followed by weight loss starting at about 6-7 weeks of age as expected for the Npc1 -/phenotype [44,45]. In the double knockout Npc1 -/-/Pcsk9 -/mice, both male (n = 6) and female (n = 7) mice were similar to the Npc1 -/-/Pcsk9 ctrl mice, showing a similar weight loss pattern consistent with the phenotype of Npc1 -/mutant mice alone ( Figure 1A,B).…”

Plasmid DNA gene therapy of the Niemann-Pick C1 mouse with transferrin receptor-targeted Trojan horse liposomes

“…The astrogliosis observed in this study (Fig. 5 ), as well as microglial activation, begins in brain of the NPC1 −/− mouse as early as 2 weeks of age 33 , 34 . Suppression of myelin production begins as early as 5 weeks of age 35 .…”

Glial contribution to cyclodextrin-mediated reversal of cholesterol accumulation in murine NPC1-deficient neuronsin vivo

“…Previous studies showed activation of glial cells in the CNS of NPC patients and animal models with distinct cell type-and region-specific onsets (Baudry et al, 2003;Cologna et al, 2014;Cougnoux et al, 2018;Cougnoux et al, 2020;Gabande-Rodriguez et al, 2019;German et al, 2002;Kavetsky et al, 2019;Lopez et al, 2011;Luan et al, 2008;Maue et al, 2012;Maulik et al, 2012;Park et al, 2019;Pressey et al, 2012;Repa et al, 2007;Santiago-Mujica et al, 2019;Seo et al, 2014;Stein et al, 2012;Tanaka et al, 1988;Walterfang et al, 2020;Yan et al, 2014a;Yan et al, 2014b). We asked how retinal glial cells react to the absence of NPC1 in 4-weeks-old mice.…”