Frataxin deficiency in the astrocytes drives neurocognitive impairment in sickle cell disease mice

Individuals with sickle cell disease (SCD) suffer from a high burden of cerebrovascular lesions and cognitive impairment that vastly impact quality of life. Cerebrovascular lesions are characterized by microstructural neuroaxonal damage, but their pathogenesis has not been fully elucidated. Herein, we report that SCD mice (SS) have reduced expression of frataxin (FXN), a mitochondrial protein, in their astrocytes compared to control (AA) mice. Next, we generated chimeric mice with SS bone marrow and astrocyte-specific deletion of FXN (SSFXN-KO). Ex-vivo diffusion tensor magnetic resonance imaging and immunohistopathology of the brain showed that the SSFXN-KO mice have increased white matter neuroaxonal damage compared to the SS bone marrow chimera mice with wild-type FXN expression (SSFXN-WT). The SSFXN-KO mice also displayed poorer cognitive function as measured by the functional Y-maze and novel object recognition tests. Pharmacological induction of FXN by administration of insulin growth factor-1 improved cognitive function in the SSFXN-KO mice. Overall, our data demonstrate that FXN is a critical factor regulating neuroaxonal health and cognitive function in SCD mice. FXN may therefore be a novel pharmacologic target to prevent cerebrovascular complications in SCD.