CD4+ T cell effector activities accelerate Alzheimer's disease pathologies.

Alzheimer's disease (AD) is a progressive neurodegenerative disorder characterized by cognitive impairments linked to pathological deposition of misfolded self-protein amyloid beta (Aβ) which in kind facilitates tau aggregation and neurodegeneration. Neuroinflammation is accepted as key disease driver caused by innate microglia activation. Recently, adaptive immune alterations have been uncovered beginning early and extending throughout the disease. How these occurs and whether they can be harnessed to affect disease progress is unclear. We propose that self-antigens would induct autoreactive effector T cells (Teff) serving to drive pro-inflammatory and neurodestructive immunity. Here, we investigated the role of effector immunity could affect cellular level disease pathobiology in an AD animal model.Aβ-specific Th1 and Th17 Teff were induced by Aβ-immunization of donors, CD4+ T cells isolated, expanded by selective culture in the presence of Aβ, and cloned as monoclonal Teff lines. Aβ-specific Th1 and Th17 Teff were adoptively transferred into the APP/PS1 double transgenic mice. Three weeks after transfer, radial arm water maze (RAWM), biochemical, immunohistochemical and transcriptomic tests assessed memory functions, pathologies, and mechanism.Development of stable monoclonal Aβ-Th1 and Aβ-Th17 cells was verified by specific cytokine signatures, nuclear transcription factors and haplotype matched major histocompatibility-II (MHCII)-Aβ tetramer staining. Accelerated memory impairments were observed in APP/PS1 mice that received Aβ-specific Teffs. Both Aβ-Th1 and Aβ-Th17 cells significantly induced pro-inflammatory cytokines TNF-α, IFN-γ and IL-17 and transcription factors Tbet and RORγ compared to controls in the periphery. Aβ load significantly increased while synaptic plasticity decreased in the brain of AD mice received Aβ-Th1 cells. Aβ-Teff driven systemic inflammatory responses were attributed to the decreased numbers and functions of regulatory T cells (Treg) in both the CNS and periphery. Additionally, transferred Aβ-Teff increased microglia reactivity and neuroinflammatory activities in the affected brain regions.Autoreactive Aβ-Teff transform a pro-inflammatory microenvironment accelerating AD pathology. This is sped by limiting Treg activities. Control of this neurodestructive environment represents a potential therapeutic strategy and can be sped by augmenting peripheral Treg numbers and function. Similar therapeutic ends have been shown to be efficacious in both pre-clinical and clinical trials in related neurodegenerative disorders.