神保 恵理子

Niemann–Pick disease type C1 (NPC1) is an autosomal recessive lysosomal storage disorder caused by pathogenic variants of the NPC1 gene that encodes a protein essential for lysosomal cholesterol transport. A deficiency in NPC1 results in the accumulation of unesterified cholesterol and sphingolipids, leading to neurological, psychiatric, and hepatic manifestations from infancy to adulthood. The currently approved treatment is palliative. Although the efficacy of gene therapy has been demonstrated in murine models, reliable biomarkers for evaluating the treatment effects remain unknown. We evaluated adeno-associated virus (AAV) vector-mediated NPC1 gene therapy in Npc1 homo-knockout ( Npc1 ^−/− ) mice, focusing on blood-based biomarkers. An AAV vector carrying human NPC1 under a cytomegalovirus promoter (AAV- hNPC1 ) was administered intraperitoneally on days 6–8 after birth at varying vector doses and analyzed at multiple time points: 1.8 × 10 ¹¹ vector genomes/mouse analyzed at 7 weeks (Low/7w) and 1.0 × 10 ¹² vector genomes/mouse at 4 weeks (High/4w) and 9 weeks (High/9w). hNPC1 is expressed in the brain and liver, and a degree of neuronal cell survival is observed. High-dose AAV treatment improves body weight and rotarod performance. Plasma N -palmitoyl- O -phosphocholine-serine (PPCS) and lysosphingomyelin (lyso-SM) levels were significantly elevated in Npc1 ^−/− mice. PPCS increased with disease progression but was significantly decreased after later points of high-dose AAV treatment (saline-treated Npc1 ^−/− mice: 12.88 ± 3.53 ng/mL, AAV-treated Npc1 ^−/− mice: 7.87 ± 1.67 ng/mL, p = 0.0008). Lyso-SM and oxysterols showed limited changes after therapy. Vector genome analysis revealed higher and more sustained levels in the brain than in the liver, which is consistent with rapid hepatocyte proliferation-reducing vector persistence. These findings demonstrate that systemic AAV- hNPC1 therapy ameliorates motor and neurological deficits but has a limited impact on several cholesterol-related biomarkers. PPCS has been suggested as a sensitive biomarker of therapeutic response and warrants further evaluations in preclinical and clinical NPC1 gene therapy trials.

Originally, apomorphine was a broad-spectrum dopamine agonist with an affinity for all subtypes of the Dopamine D1 receptor to the D5 receptor. We previously identified apomorphine as a potential therapeutic agent for mitochondrial diseases by screening a chemical library of fibroblasts from patients with mitochondrial diseases. In this study, we showed that apomorphine prevented ferroptosis in fibroblasts from various types of mitochondrial diseases as well as in normal controls. Well-known biomarkers of ferroptosis include protein markers such as prostaglandin endoperoxide synthase 2 (PTGS2), a key gene for ferroptosis-related inflammation PTGS2, lipid peroxidation, and reactive oxygen species. Our findings that apomorphine induced significant downregulation of PTSG2 and suppressed lipid peroxide to the same extent as other inhibitors of ferroptosis also indicate that apomorphine suppresses ferroptosis. To our knowledge, this is the first study to report that the anti-ferroptosis effect of apomorphine is not related to dopamine receptor agonist action and that apomorphine is a potent inhibitor of ferroptotic cell death independent of dopaminergic receptors.

BACKGROUND: Niemann-Pick disease type C (NPC) is an autosomal recessive inherited and neurodegenerative disorder. Approximately 10% of NPC patients have acute liver failure and sometimes need liver transplantation (LT), and 7% reportedly develop inflammatory bowel disease (IBD). We report the case of a girl with NPC who had a re- accumulation of cholesterol in the transplanted liver and NPC-related IBD. CASE REPORT: The patient underwent living donor liver transplantation (LDLT) due to severe acute liver failure caused by an unknown etiology inherited from her father. At 1 year and 6 months (1Y6M), she developed neurological delay, catalepsy, and vertical supranuclear gaze palsy. The foam cells were found in her skin, and fibroblast Filipin staining was positive; hence, she was diagnosed with NPC. It was identified that her father had NPC heterozygous pathogenic variant. At 2 years, she had anal fissure, skin tag and diarrhea. She was diagnosed with NPC-related IBD, using a gastrointestinal endoscopy. Three years after LT, liver biopsy revealed foam cells and numerous fatty droplets. At 8 years, broken hepatocytes and substantial fibrosis were observed. She died from circulation failure due to hypoalbuminemia at 8Y2M. CONCLUSIONS: In NPC, load of cholesterol metabolism is suggested to persist even after LT. LDLT from NPC heterozygous variant donor was insufficient to metabolize cholesterol overload. In NPC patients, the possibility of cholesterol re-accumulation should be considered when LT is performed. NPC-related IBD should be considered when NPC patients have anorectal lesions or diarrhea.

Coenzyme Q10 (CoQ10) is involved in ATP production through electron transfer in the mitochondrial respiratory chain complex. CoQ10 receives electrons from respiratory chain complex I and II to become the reduced form, and then transfers electrons at complex III to become the oxidized form. The redox state of CoQ10 has been reported to be a marker of the mitochondrial metabolic state, but to our knowledge, no reports have focused on the individual quantification of reduced and oxidized CoQ10 or the ratio of reduced to total CoQ10 (reduced/total CoQ10) in patients with mitochondrial diseases. We measured reduced and oxidized CoQ10 in skin fibroblasts from 24 mitochondrial disease patients, including 5 primary CoQ10 deficiency patients and 10 respiratory chain complex deficiency patients, and determined the reduced/total CoQ10 ratio. In primary CoQ10 deficiency patients, total CoQ10 levels were significantly decreased, however, the reduced/total CoQ10 ratio was not changed. On the other hand, in mitochondrial disease patients other than primary CoQ10 deficiency patients, total CoQ10 levels did not decrease. However, the reduced/total CoQ10 ratio in patients with respiratory chain complex IV and V deficiency was higher in comparison to those with respiratory chain complex I deficiency. Measurement of CoQ10 in fibroblasts proved useful for the diagnosis of primary CoQ10 deficiency. In addition, the reduced/total CoQ10 ratio may reflect the metabolic status of mitochondrial disease.