Human misfolded truncated tau protein promotes activation of microglia and leukocyte infiltration in the transgenic rat model of tauopathy.

It has been hypothesized that misfolded tau protein could be a mediator of the inflammatory response in human tauopathies. Here we show that neurodegenerative lesions caused by human truncated tau promote inflammatory response manifested by upregulation of immune-molecules (CD11a,b, CD18, CD4, CD45 and CD68) and morphological activation of microglial cells in a rat model of tauopathy. In parallel, the innate immune brain response promotes activation of MHC class II positive blood-borne leukocytes and their influx into the brain parenchyma. These findings have important consequences for the rationale drug development of effective inflammation-based therapeutic strategies for human tauopathies.