Bergmann glia are reduced in spinocerebellar ataxia type 1

Non-cell-autonomous pathology involving glial cells has been implicated in Purkinje cell degeneration. We reported previously that mutant ataxin-1, a causative gene product of spinocerebellar ataxia type 1 (SCA1), prevents Bergmann glia proliferation in mutant ataxin-1 knockin mice and that suppressed Bergmann glia function leads to Purkinje cell degeneration. However, because reactive astrocytes are produced in response to brain injuries and diseases, Bergmann glia are also suspected to proliferate and increase in response to Purkinje cell degeneration, including during SCA1 pathogenesis. However, little is known about reactive Bergmann glia (Bergmann gliosis) and its beneficial or detrimental role. Given the lack of quantitative studies of Bergmann glia using specific molecular markers, we quantified Bergmann glia in human SCA1 brains with Bergmann glia-specific Sox2 staining and conventional hematoxylin and eosin staining. Our results showed reduced numbers of Bergmann glia in SCA1 patient brains and support the hypothesis that Bergmann glia loss contributes toward Purkinje cell degeneration in human SCA1.