Transcriptome of human primary macrophages from X-linked adrenoleukodystrophy patients and healthy controls

Saturated very long-chain fatty acids (VLCFA, ≥ C22), enriched in brain myelin and innate immune cells, accumulate in X-linked adrenoleukodystrophy (X-ALD). The severest form, inherited dysfunction of the VLCFA transporter ABCD1, underlying X-ALD, causes brain myelin destruction with infiltration of pro-inflammatory skewed monocytes/macrophages. How VLCFA levels relate to macrophage activation is unclear. Using whole transcriptome sequencing of X-ALD macrophages, we revealed that VLCFAs prime human macrophage membranes for inflammation and increase factors involved in chemotaxis and invasion. When applied externally, mimicking lipid destruction in X-ALD lesions, VLCFAs did not activate toll-like receptors in healthy cells but provoked pro-inflammatory responses through scavenger receptor CD36-mediated uptake, cumulating in JNK signalling and expression of matrix degrading enzymes and chemokine release. Following pro-inflammatory LPS-activation, VLCFA accumulated in healthy macrophages but were rapidly cleared with onset of resolution by increasing VLCFA degradation through liver-X-receptor mediated upregulation of ABCD1. ABCD1 deficiency impaired VLCFA homeostasis and prolonged pro-inflammatory gene expression. Our study uncovers a pivotal role for ABCD1, a protein linked to neuroinflammation, and associated peroxisomal VLCFA degradation in regulating macrophage plasticity. Comparative gene expression profiling analysis of RNA-seq data for macrophages derived from X-ALD patients and control blood-isolated monocytes.