Astrocytic frataxin deficiency drives neurocognitive impairment in sickle cell mice

Individuals with sickle cell disease (SCD) suffer from a high burden of neurocognitive impairment. Cerebrovascular lesions, characterized by diffusion tensor imaging identified neuroaxonal damage, are associated with learning and memory deficits. The molecular and cellular intermediates driving microstructural neuroaxonal damage and cognitive impairment in SCD remain largely unexplored. Herein, we report that sickle cell mice (SS) have reduced expression of frataxin (FXN), a mitochondrial protein, in their astrocytes compared with normal control (AA) mice. A newly generated sickle bone marrow chimeric mouse with astrocyte-specific deletion of FXN (SS^FXN-KO) showed worsening white-matter neuroaxonal damage compared with the normal mice lacking astrocytic FXN (AA^FXN-KO) as well as with the SS mice with wild-type FXN expression (SS^FXN-WT). The SS^FXN-KO mice exhibited impaired cognitive function assessed by the functional novel object recognition (NOR) tests. Induction of FXN improved cognitive responses in the SS mice. Overall, our data demonstrate that astrocytic FXN plays a pivotal role in regulating neuroaxonal health and cognitive function in SCD.