microRNA-132 attenuates inflammation in induced pluripotent stem cell-derived microglia from Alzheimer's disease patients

Microglia, the resident immune cells of the brain, are increasingly recognized as key contributors to Alzheimer’s disease (AD) pathology. Multiple studies have identified microRNA-132 (miR-132) as one of the most significantly downregulated microRNAs in AD. Apart from well-established pleiotropic regulatory functions in neurons, previous evidence also suggested a role for miR-132 in regulating (neuro)inflammation. Yet, the precise mechanisms by which miR-132 impacts microglia remain unknown. In this study, we investigated the role of miR-132 in modulating microglial gene expression and function using gain- and loss-of-function approaches in human-induced pluripotent stem cell (iPSC)-derived microglia (iMGs) from both healthy controls and sporadic AD (sAD) patients. Our findings indicate that while miR-132 may not be indispensable for some baseline microglial functions, increasing its expression in sAD iMGs can reverse disease-associated gene expression changes and attenuate inflammatory responses. To further explore its therapeutic potential, we overexpressed miR-132 in hippocampal neurons of an AD mouse model, employing a clinically relevant adeno-associated viral (AAV) delivery method. miR-132 overexpression was well-tolerated and induced non-cell autonomous effects in microglia. This study sheds light into the regulatory role of miR-132 in microglia under both physiological and AD conditions, and emphasizes the importance of optimizing safe dosage parameters for future clinical applications.