Impact of the interplay between microglia, astrocytes and infiltrating immune cells in neuroinflammatory mechanisms in Alzheimer’s disease.

Alzheimer’s disease (AD), the prevalent age-associated neurodegenerative disease, is associated with neuroinflammation and impaired immunity. Microglia, the brain resident immune cells, are often looked at as responsible for this pathological cascade [1]. However, growing evidence shows the contribution of peripheral immune cells and astrocytes to the brain immune responses in AD. The astrocytes, mainly known for their metabolic support to neurons, can secrete a plethora of pro-inflammatory cytokines under reactive profiles and alter the responses of surrounding microglia [2,3]. Furthermore, CD8+ T cells have been shown to infiltrate parenchyma in neurodegeneration areas and could derail inflammation [4].
Deciphering microglia interplays with astrocytes and T cells will unveil new facets of neuroinflammation in AD and potentially open new therapeutic strategies to alleviate the progression of the disease.
We propose investigating their interactions using a translational approach based on co-cultures of human cells, on single nuclei-RNAseq analysis and high-resolution microscopy of AD post-mortem tissue. Briefly, we will use human cells, isolated or induced, to study the impact of cytotoxic lymphocytes and reactive astrocytes (chemically induced) on the physiology of microglia in mono or 3D co-culture models. We will use a complete set of molecular screening (methylation profiling, PCR, WB, secretome, and metabolic signatures), time-lapse microscopy and super-resolution shadow imaging (SUSHI) to characterize their phenotypic changes and cellular interactions.
In parallel, we will analyze the transcriptome of immune and brain cells in vulnerable regions by single-nuclei RNAseq (10x) in our collection of frozen AD brain samples. We will decode regional immune signatures and characterize respective local cellular relationships using neuropathology, confocal microscopy [5] and correlative light electron microscopy.