They observed that, after injecting amyloid β1-42 (Aβ1-42) into the hippocampus of rats to induce AD, there was a disruption of the BBB, with the infiltration of Th17 cells in the cerebral parenchyma detected by an increase in the staining for the transcription factor RORγT; this was in addition to an increase in the expression of proinflammatory cytokines IL-17 and IL-22 [139,147]. This evidence concerns the gene IL17A and Alzheimer disease.