RT Journal Article SR Electronic T1 Microglial CX3CR1I249/M280 variant limits neurogenesis and remyelination in cuprizone-induced multiple sclerosis model JF bioRxiv FD Cold Spring Harbor Laboratory SP 2021.06.06.447262 DO 10.1101/2021.06.06.447262 A1 Andrew S. Mendiola A1 Kaira A. Church A1 Sandra M. Cardona A1 Difernando Vanegas A1 Shannon A. Garcia A1 Wendy Macklin A1 Sergio A. Lira A1 Richard M. Ransohoff A1 Erzsebet Kokovay A1 Chin-Hsing Annie Lin A1 Astrid E. Cardona YR 2021 UL http://biorxiv.org/content/early/2021/06/07/2021.06.06.447262.abstract AB Microglia have been implicated in multiple sclerosis (MS) pathogenesis. The fractalkine receptor CX3CR1 regulates the activation of pathogenic microglia in models of MS and the human polymorphic CX3CR1I249/M280 (hCX3CR1I249/M280) variant increases MS disease progression. However, the role of hCX3CR1I249/M280 on microglial activation and central nervous system repair and regenerative mechanisms remain unknown. Therefore, using transgenic mice expressing the hCX3CR1I249/M280 variant, we aimed to determine the contribution of defective CX3CR1 signaling to remyelination and neurogenesis in the cuprizone model of focal demyelination. Here, we report that mice expressing hCX3CR1I249/M280 exhibit marked demyelination and microgliosis follow acute cuprizone treatment. Cuprizone-treated CX3CR1-deficient and fractalkine-deficient mice displayed a comparable phenotype. Nanostring gene expression analysis in demyelinated lesions showed that hCX3CR1I249/M280 upregulates genes associated with inflammation, oxidative stress and disease-associated microglia. In addition, gene expression analysis in the subgranular zone (SGZ) of the hippocampus in hCX3CR1I249/M280 mice was associated with a significant downregulation of gene networks linked to neurogenesis following acute demyelination. Confocal microscopy showed that hCX3CR1I249/M280 or loss of CX3CR1 signaling inhibits the generation of progeny from the neurogenic niche, including cells involved in myelin repair. These results provide evidence for the pathogenic capacity of hCX3CR1I249/M280 on microglia dysfunction and therapeutic targeting of CX3CR1 to promote CNS repair in MS.Competing Interest StatementThe authors have declared no competing interest.