Emmanuel Mignot discusses the potential protective effects of a variant of an immune system gene against neurodegenerative diseases. The podcast explores the role of HLA genes in the immune system, their association with Parkinson's and Alzheimer's diseases, and the potential mechanism for efficient removal of tau protein. The researchers also propose a potential immune system mechanism in clearing acetylated tau to prevent neurodegenerative diseases. Additionally, the podcast explores the potential of a vaccine to protect against neurodegenerative diseases by enhancing the immune response and clearing tau aggregates.