Accumulation of ether phospholipids in induced pluripotent stem cells and oligodendrocyte-lineage cells established from patients with Sjögren-Larsson syndrome

Abstract

Sjögren-Larsson syndrome (SLS) is an autosomal recessive leukodystrophy characterized by ichthyosis, intellectual disability, and progressive spastic paralysis caused by biallelic pathogenic variants in the ALDH3A2 gene that encodes the fatty aldehyde dehydrogenase, fatty aldehyde dehydrogenase (FALDH); FALDH catalyzes several metabolic reactions involved in fatty aldehyde oxidation. Only a few studies have been performed to determine the lipid profile of patients with SLS. In a previous postmortem study of the brain of a 65-year-old patient with SLS, lipidomic analysis revealed an accumulation of long-chain unsaturated ether lipid species in the white matter and gray matter. In the present study, we established a disease model using patient-derived neuronal and oligodendrocyte lineage cells to analyze the lipid metabolism and gene expression profiles in SLS. To achieve this, we generated induced pluripotent stem cells (iPSCs) from two patients with the SLS phenotype carrying previously known ALDH3A2 pathogenic variants: One was a compound heterozygote (c.1339A>G:p.(Lys447Glu) and c.57_132dup:p.(Ile45Serfs*34)) and the other was a homozygote (c.1339A>G: p.(Lys447Glu)). The FALDH activity was almost zero in the SLS-iPSC lines established from both patients. Phospholipid analysis of neurospheres, and oligospheres (spheres enriched with oligodendrocyte-lineage cells) derived from the iPSCs by liquid chromatography-mass spectrometry showed accumulation of ether phospholipids in the Sjögren-Larsson patient-derived neurospheres and oligospheres. The results are consistent with the previously reported accumulation of ether lipids in the postmortem brain tissue of an SLS patient. Therefore, iPSCs and iPSC-derived neurospheres and oligospheres established from SLS patients can be useful tools for future pathological analysis of the central nervous system pathophysiology in SLS.

Keywords: FALDH; Sjögren‐Larsson syndrome; ether phospholipid; induced pluripotent stem cells; oligodendrocytes.