Human optic chiasm from healthy controls and multiple sclerosis patients

Changes in gene expression that occur across the entire central nervous system (CNS) during disease do not take into account variability from one CNS region to another and can be confounded by alterations in cellular composition during disease. Multiple sclerosis (MS) is characterized by cell proliferation, migration and damage in various cell types in different CNS regions and causes disabilities related to distinct neurological pathways, such as walking, vision and cognition. Here, a cell-specific and region-specific transcriptomic approach was used to determine changes in gene expression in astrocytes derived from spinal cord, cerebellum, cerebral cortex, and hippocampus in the preclinical MS model, chronic experimental autoimmune encephalomyelitis (EAE). RNA sequencing and bioinformatics analysis showed that changes in gene expression pathways in astrocytes differed between neuroanatomic regions. Further, while astrocytes from spinal cord showed increased expression of immune pathway genes during EAE, cholesterol biosynthesis pathway genes were decreased. Translating these findings from the preclinical model to humans, optic nerve from EAE and optic chiasm from MS each showed a significant decrease in cholesterol biosynthesis pathways. Finally, a treatment targeting cholesterol homeostasis in astrocytes was protective in EAE, suggesting a novel neuroprotective strategy for MS. Using a cell-specific and region-specific gene expression approach can provide therapeutically relevant insights into mechanisms underlying specific disabilities in complex multifocal neurological diseases. Five MS patients (average age = 57.6 years) and five age-matched healthy controls (average age = 56.2 years) fresh frozen autopsy optic chiasm tissue samples were obtained from Human Brain and Spinal Fluid Research Center in Los Angeles.