X-linked adrenoleukodystrophy patient fibroblast-iPSC-derived astrocytes reveal phenotype-specific metabolic, inflammatory, and microRNA alterations

Abstract: Objective: The role of astrocytes largely remains to be explored in X-linked adrenoleukodystrophy (X-ALD). Due to limited study models and inaccessibility to patient-tissue samples, we differentiated astrocytes from patient fibroblast-derived induced pluripotent stem cell (iPSCs) which provided a unique system to investigate molecular and etiopathogenetic mechanisms, identify targets, and develop therapeutic agents for X-ALD. Methods: We reprogrammed fibroblasts from adrenomyeloneuropathy (AMN) and cerebral adrenoleukodystrophy (cALD) patients carrying ABCD1 with pathogenic variants and a control patient to generate iPSCs. We differentiated iPSCs into astrocytes and performed transmission electron microscopy, gene expression, immunoblotting, enzyme-linked immunosorbent assay, miRNA-Seq, and lipidomics to characterize phenotypic and molecular features of patient-derived astrocytes. Results: These differentiated astrocytes exhibit diseased phenotypes and replicate biochemical and molecular changes found in patients. We confirmed the deletion of ABCD1 gene-encoded ALD protein and identified ABCD1 variant-driven very long chain fatty acid deposition in AMN and cALD astrocytes. Especially, cALD astrocytes showed increased glycolysis, increased signal transducer and transcription activator (STAT)3 activation, higher miR-9 expression in miRNA-Seq analysis, and reduced expression of anti-inflammatory cytokines such as arginase-1 and mannose receptor C-type-1. Consequently, Toll-like receptor-signaling via myeloid differentiation primary response gene 88 (MyD88) and nuclear factor-kappa B (NF-κB; p52 and p65) induced STAT3 and an altered miR-9 expression is a potential contributor to inflammatory milieu in cALD while interleukin-6 -induced anti-inflammatory cytokine production and increased chemotactic CCL-2 (MCP-1) production in AMN potentially favors microglial recruitment protecting its further progression. Interpretation: We demonstrate for the first time that patient iPSC-derived astrocytes mimic and recapitulate neuroinflammatory and biochemical defects of X-ALD and provide an in vitro cellular system to study X-ALD.