iPSC-derived astrocytes to model phenotype-specific differential neuroinflammatory and metabolic responses in X-linked adrenoleukodystrophy

Abstract

X-linked adrenoleukodystrophy (X-ALD) is an inherited progressive metabolic disorder caused by pathogenic variants in the ABCD1 gene, which leads to accumulation of very long chain fatty acids in body fluids and tissues including brain and spinal cord. In the absence of a clear genotype-phenotype correlation the molecular mechanisms of the severe 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 from healthy controls and patients with AMN or cALD. AMN and cALD astrocytes exhibited lack of ABCD1 and accumulation of very long chain fatty acids, a hallmark of X-ALD disease. Further, cALD astrocytes harbor significantly higher phosphorylation of STAT3, increased Toll-like receptor expression and higher chemokine and cytokine expression. In this first report of miRNA sequencing in X-ALD astrocytes, we observed that miR-9 expression was associated with increasing disease severity phenotype. CRISPR-Cas9 knock-in of ABCD1ABCD1 gene expression differentially affected the expression of key molecular, metabolic and microRNA targets in AMN and cALD astrocytes. Extensive characterization of the AMN and cALD iPSC-derived astrocyte model demonstrates critical aspects of X-ALD inflammatory disease in response to ABCD1ABCD1 mutation and can be further utilized for exploring the contribution of astrocytes to differential inflammatory response in cALD.