Senescence as a Central Node in Alzheimer's Disease: Molecular Triggers, Cellular Effectors, and RNA-Based...

Alzheimer's disease (AD) is the most frequent neurodegenerative disorder. It is characterized by the buildup of amyloid-β (Aβ) plaques, as well as of tangles made out of tau that increasingly damage and kill neurons while also impairing memory and thinking. Recent findings indicate that cellular senescence is implicated in the pathogenesis of AD. Senescence occurs when cells irreversibly stop dividing under stress. In the brain, it can be induced by chronic activation of astrocytes and microglia, Aβ toxicity, tau hyperphosphorylation and oxidative stress. Senescent cells secrete proinflammatory factors, i.e., the senescence-associated secretory phenotype (SASP). These molecules promote inflammation, destroy mitochondria and interfere with synapses in ways that speed up the progress of the disease. Blocking those senescent cells may offer a new approach to treatment. Approaches including VEGFR-1 and SIRT5 interference, senolytics or senomorphs drugs, NLRP3 antagonist, PAI-1 inhibitors and small vessels inhibitors (including aspirin, curcumin derivatives and sildenafil) have been suggested to promisingly mitigate brain injury. RNA based therapy (miRNAs- and lncRNAs-targeted) and exosomal derived biomarkers are also an optimistic approach. A clearer understanding of how senescence is implicated in AD would have implications regarding the design and application of novel treatments aimed at delaying disease onset, slowing down progression or preserving brain function.