amphotericin-b and Adrenoleukodystrophy

Cholesterol is dynamically transported among organelles, which is essential for multiple cellular functions. However, the mechanism underlying intracellular cholesterol transport has remained largely unknown. We established an amphotericin B-based assay enabling a genome-wide shRNA screen for delayed LDL-cholesterol transport and identified 341 hits with particular enrichment of peroxisome genes, suggesting a previously unappreciated pathway for cholesterol transport. We show dynamic membrane contacts between peroxisome and lysosome, which are mediated by lysosomal Synaptotagmin VII binding to the lipid PI(4,5)P2 on peroxisomal membrane. LDL-cholesterol enhances such contacts, and cholesterol is transported from lysosome to peroxisome. Disruption of critical peroxisome genes leads to cholesterol accumulation in lysosome. Together, these findings reveal an unexpected role of peroxisome in intracellular cholesterol transport. We further demonstrate massive cholesterol accumulation in human patient cells and mouse model of peroxisomal disorders, suggesting a contribution of abnormal cholesterol accumulation to these diseases.

Topics: Adrenoleukodystrophy; Amphotericin B; Animals; ATP-Binding Cassette Transporters; Biological Transport; Cholesterol; Genome-Wide Association Study; Humans; Lysosomes; Mice; Peroxisomal Disorders; Peroxisomes; Phosphatidylinositol 4,5-Diphosphate; RNA, Small Interfering; Synaptotagmins; Zebrafish

We describe a 9-yr-old boy who received the highest cumulative dose so far reported of liposomal amphotericin B. The patient underwent an allogeneic bone marrow transplantation (BMT) for adrenoleucodystrophy, after a conditioning regimen with busulfan, thiothepa and cyclophosphamide. Rabbit antithymoglobulin, cyclosporin and prednisone were used as prophylaxis against graft vs. host disease (GVHD). Post-transplant Epstein-Bar-virus-related lymphoma was diagnosed on day +68 and was treated with donor-derived lymphocytes. The patient developed a severe form of GVHD, and a progressive worsening of his neurological status because of progression of his underlying disease. Death from septic shock occurred 23 months after BMT. During prolonged hospitalization, 19,750 mg of liposomal amphotericin B, about 1000 mg/kg, were given for prophylactic or empirical therapeutic purposes without significant nephrotoxicity. This case suggests that liposomal amphotericin B is safe and well-tolerated even if is administered for long periods and a cumulative dose fivefold greater than the nephrotoxic threshold of amphotericin B deoxycholate is achieved.

Topics: Adrenoleukodystrophy; Amphotericin B; Antifungal Agents; Bone Marrow Transplantation; Candidiasis; Child; Creatinine; Disease Progression; Epstein-Barr Virus Infections; Fatal Outcome; Graft vs Host Disease; Humans; Kidney; Kidney Diseases; Liposomes; Lymphoma; Male; Pseudomonas Infections; Shock, Septic; T-Lymphocytes, Cytotoxic; Transplantation Conditioning