The MR1/MAIT cell axis reduces dystrophic neurite development in Alzheimer’s disease

Plaques are a hallmark feature of Alzheimer’s disease (AD). We found that the loss of mucosal-associated invariant T (MAIT) cells and its antigen-presenting molecule MR1 caused a delay in plaque pathology development in AD mouse models. However, it remains unknown how this axis is impacting dystrophic neurites. Brain tissue from 5XFAD mice and those that are MR1-deficient (MR1 KO), were analyzed for dystrophic neurites, amyloid plaques, and synapses via immunofluorescence, RNA sequencing, ELISA, and Western blot. In 8-month-old 5XFAD/MR1 KO mice, there was reduced expression of LAMP1, Ubiquitin, and n-terminal APP in the hippocampus as compared to 5XFAD mice (p < 0.05). 5XFAD/MR1 KO mice also had less insoluble Aβ40 (p < 0.001) and higher levels of PSD95 (p < 0.01) in the hippocampus. Our data contribute additional mechanistic insight into the detrimental role of the MR1/MAIT cell axis in AD pathology development. Hippocampal samples from 8 month old 5XFAD and 5XFAD/MR1 KO mice, with a male and female mouse pooled together for 1 sample