The Npc2Gt(LST105)BygNya mouse signifies pathological changes comparable to human Niemann-Pick type C2 disease.

INTRODUCTION: Niemann-Pick type C2 disease (NP-C2) is a fatal neurovisceral disorder caused by defects in the lysosomal cholesterol transporter protein NPC2. Consequently, cholesterol and other lipids accumulate within the lysosomes, causing a heterogeneous spectrum of clinical manifestations. Murine models are essential for increasing the understanding of the complex pathology of NP-C2. This study, therefore, aims to describe the neurovisceral pathology in the NPC2-deficient mouse model to evaluate its correlation to human NP-C2. METHODS: Npc2-/- mice holding the LST105 mutation were used in the present study (Npc2Gt(LST105)BygNya). Body and organ weight and histopathological evaluations were carried out in six and 12-week-old Npc2-/- mice, with a special emphasis on neuropathology. The Purkinje cell (PC) marker calbindin, the astrocytic marker GFAP, and the microglia marker IBA1 were included to assess PC degeneration and neuroinflammation, respectively. In addition, the pathology of the liver, lungs, and spleen was assessed using hematoxylin and eosin staining. RESULTS: Six weeks old pre-symptomatic Npc2-/- mice showed splenomegaly and obvious neuropathological changes, especially in the cerebellum, where initial PC loss and neuroinflammation were evident. The Npc2-/- mice developed neurological symptoms at eight weeks of age, severely progressing until the end-stage of the disease at 12 weeks. At the end-stage of the disease, Npc2-/- mice were characterized by growth retardation, tremor, cerebellar ataxia, splenomegaly, foam cell accumulation in the lungs, liver, and spleen, brain atrophy, pronounced PC degeneration, and severe neuroinflammation. CONCLUSION: The Npc2Gt(LST105)BygNya mouse model resembles the pathology seen in NP-C2 patients and denotes a valuable model for increasing the understanding of the complex disease manifestation and is relevant for testing the efficacies of new treatment strategies.

Protein replacement therapy partially corrects the cholesterol-storage phenotype in a mouse model of Niemann-Pick type C2 disease.

Niemann-Pick type C2 (NPC2) disease is a fatal autosomal recessive neurovisceral degenerative disorder characterized by late endosomal-lysosomal sequestration of low-density lipoprotein derived cholesterol. The breach in intracellular cholesterol homeostasis is caused by deficiency of functional NPC2, a soluble sterol binding protein targeted to the lysosomes by binding the mannose-6-phosphate receptor. As currently there is no effective treatment for the disorder, we have investigated the efficacy of NPC2 replacement therapy in a murine gene-trap model of NPC2-disease generated on the 129P2/OlaHsd genetic background. NPC2 was purified from bovine milk and its functional competence assured in NPC2-deficient fibroblasts using the specific cholesterol fluorescent probe filipin. For evaluation of phenotype correction in vivo, three-week-old NPC2(-/-) mice received two weekly intravenous injections of 5 mg/kg NPC2 until trial termination 66 days later. Whereas the saline treated NPC2(-/-) mice exhibited massive visceral cholesterol storage as compared to their wild-type littermates, administration of NPC2 caused a marked reduction in cholesterol build up. The histological findings, indicating an amelioration of the disease pathology in liver, spleen, and lungs, corroborated the biochemical results. Little or no difference in the overall cholesterol levels was observed in the kidneys, blood, cerebral cortex and hippocampus when comparing NPC2(-/-) and wild type mice. However, cerebellum cholesterol was increased about two fold in NPC2(-/-) mice compared with wild-type littermates. Weight gain performance was slightly improved as a result of the NPC2 treatment but significant motor coordination deficits were still observed. Accordingly, ultrastructural cerebellar abnormalities were detected in both saline treated and NPC2 treated NPC2(-/-) animals 87 days post partum. Our data indicate that protein replacement may be a beneficial therapeutic approach in the treatment of the visceral manifestations in NPC2 disease and further suggest that neurodegeneration is not secondary to visceral dysfunction.

The toxicity of bovine α-lactalbumin made lethal to tumor cells is highly dependent on oleic acid and induces killing in cancer cell lines and noncancer-derived primary cells.

A complex between α-lactalbumin and oleic acid (C18:1, 9 cis) has been reported to be cytotoxic to cancer cells. We have prepared such complexes and tested their activity against both cancer cell lines and noncancer-derived primary cells. Unexpectedly, some primary cell types were more sensitive to treatment than cancer cell lines. We found the complex to be cytotoxic to all of the tested cells, with a 46-fold difference between the most sensitive and the least sensitive cell type. Oleic acid by itself exhibited a remarkably similar activity. The cell-killing mechanisms of the complex and of oleic acid alone were examined by flow cytometry, testing for apoptosis- and necrosis- inducing activity. The T-cell leukemia-derived Jurkat cells primarily underwent cell death resembling apoptosis, whereas the monocytic leukemia-derived THP1 cells adopted a more necrotic-like cell death. Erythrocytes were sensitive to lysis by the complex and oleic acid. We conclude that oleic acid is cytotoxic by itself and that, in contrast to the literature, a complex of α-lactalbumin and oleic acid has cytotoxic activity against primary cells, as well as cancer cells.