Emerging evidence suggests that certain populations of fully differentiated neurons in the brain may undergo a cell cycle-like process during both normal aging and certain neurodegenerative diseases. For two decades since their first discoveries in the 90s, histology-based techniques remained as the mainstay study approaches of these cells. However, due to their scarcities and unpredictable distributions within the brain, the molecular profiles and specific variations associated with these cells remain unclear. We are the first group to devise a bioinformatics solution that allows integrated analyses of multiple single-nucleus transcriptome datasets to identify and characterize these rare cell populations [Selected publication #1].The robustness of this tool is validated in multiple independent cohorts of human brain samples obtained from individuals with Alzheimer’s disease (AD), as well as in datasets of human Parkinson’s Disease-Lewy Body Dementia (PD-LBD) and a mouse model of brain aging [Selected publication #1]. We are also the very first group identified the key molecular differences in cell cycle re-engaging senescent neurons emerged from human AD versus non-affected brains, tying to aberrant fuel metabolism related to chronic insulin signalling [Selected publication #1].This indeed validated our earlier findings in mice published in 2019 [Selected publication #5], which reported age-related hyperinsulinemia leads to insulin resistance in neurons and cell-cycle-induced senescence. Building upon these finding, we have ongoing work understanding how life style risk factors of AD is linked to this cellular phenomenon, such as binge drinking [Selected publication #4].
The pressing issue of an aging population has prompted policymakers to prioritize strategies aimed at maintaining good health among the public. By performing an integrated analysis using multiple human blood transcriptome and DNA methylome data, our work presents an initial exploration of how the innate immune system in human (instead of the adaptive immune system reported in other studies) contributes to extreme longevity and overall well-being in multiple cohorts of long lived individuals from various geographical origins and ethnicities [Selected publication #3]. Specifically, our major findings demonstrate that the life cycle and phagocytic activities of innate monocytes, extracted from aging champions and supercentenarians belonging to various ethnic backgrounds, exhibit a consistent enhancement which is supported by an immune-metabolic network influenced by insulin signalling, as also matched with the findings from the Monozygotic Twin Study. This therefore emphasizes the significance of preserving insulin sensitivity as a critical factor in promoting health span and extending lifespan, complementing the relationship between insulin resistance/ type 2 diabetes and the development of various non-communicable diseases, including AD/ADRD. Our previous studies indeed also highlighted that insulin resistance in neurons is related to accelerated brain aging and functional decline [Selected publication #5]; and that occurs in microglia is associated with defective phagocytosis, more advanced pathologies and cognitive decline in female AD brains [Selected publication #2].