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.