IPSC-Derived Astrocytes to Model Neuroinflammatory and Metabolic Responses in X-linked Adrenoleukodystrophy

X-linked adrenoleukodystrophy (X-ALD) is an inherited metabolic disorder caused by pathogenic variants in the ABCD1 gene, leading to accumulation of saturated very long chain fatty acids (VLCFA) in body fluids and tissues including brain and spinal cord. In the absence of a clear genotype-phenotype correlation the molecular mechanisms of the fatal cerebral adrenoleukodystrophy (cALD) and the milder adrenomyeloneuropathy (AMN) phenotypes remain unknown. Given our previous evidence of role of astrocytes in the neuroinflammatory response in X-ALD we investigated the metabolic and molecular profiles of astrocytes derived from induced pluripotent stem cells (iPSC). The iPSCs were in turn generated from skin fibroblasts of healthy controls and patients with AMN or cALD. AMN and cALD astrocytes exhibited lack of ABCD1 and accumulation of VLCFA, a biochemical hallmark of X-ALD disease. Accumulation of VLCFA was significantly higher in cALD astrocytes. Mitochondrial function analysis by Seahorse extracellular flux identified increased oxygen consumption and extracellular acidification rates in cALD astrocytes, yet the ATP levels were decreased. Molecular signaling identified increased phosphorylation of STAT3 in cALD astrocytes, and higher proinflammatory cytokine and Toll like receptor (TLR) expression. CRISPR-Cas9 knock-in of functional ABCD1 gene expression differentially affected the expression of key molecular and metabolic targets in AMN and cALD astrocytes. AMN and cALD iPSC-derived astrocytes and their isogenic controls demonstrate differential aspects of X-ALD metabolic and inflammatory response to ABCD1 mutation and can be further utilized for exploring the contribution of iPSC-derived astrocytes to differential X-ALD disease pathology.