| Abstract: | Aquaporin‐4 (AQP‐4) is a water channel protein located on the plasma membrane of astrocytes and is regulated under various conditions. In the present study, a series of brains with sporadic Creutzfeldt‐Jakob disease (sCJD) were investigated to determine the possible contribution of AQP‐4 in the development of sCJD pathology. Six cases of subacute spongiform encephalopathy (SSE) and four cases of panencephalopathic (PE)‐type sCJD were included. Increased AQP‐4 immunoreactivity compared to that in controls was observed in all sCJD patients, particularly in the cerebral neocortex and cerebellar cortex. AQP‐4 immunoreactivity was present in the cell bodies and processes of protoplasmic astrocytes in SSE and around cell bodies and processes of hypertrophic astrocytes in PE‐type sCJD. Analysis of serial sections showed the development of sCJD pathology, particularly in neocortical lesions, as follows: PrP deposition; spongiform change and gliosis; enhanced staining for AQP‐4; hypertrophic astrocytosis; and neuronal loss and tissue rarefaction. Strong AQP‐4 immunoreactivity was present in burnt‐out lesions such as those of status spongiosus. These results indicate that increased AQP‐4 expression in sCJD is an early pathologic event and appears to remain until the late disease stage. We suggest that increased expression of AQP‐4 is a pathologic feature of sCJD. |
