S100B and primary biliary cholangitis: While GFAP is regarded as a marker of more chronic astrocyte activation, S100B is also expressed by other glial cells and is increased in several acute lesion situations, often accompanied by an impairment of the BBB.39,40 In contrast to GFAP, serum S100B remained unaltered, further arguing for a more chronic, long-term activation of glial cells in PBC and a slow progression of PBC pathology over years or even decades with minor neurovascular unit impairment.