IGF-1 Gene Therapy Modifies Inflammatory Environment and Gene Expression in the Caudate-Putamen of Aged Female Rat Brain

Abstract

Brain aging is characterized by chronic neuroinflammation caused by activation of glial cells, mainly microglia, leading to alterations in homeostasis of the central nervous system. Microglial cells are constantly surveying their environment to detect and respond to diverse signals. During aging, microglia undergo a process of senescence, characterized by loss of ramifications, spheroid formation, and fragmented processes, among other abnormalities. Therefore, the study of microglia senescence is of great relevance to understand age‐related declines in cognitive and motor function.We have targeted the deleterious effects of aging by implementing gene therapy with IGF-1, employing recombinant adenoviral vectors (RAds) as a delivery system. In this study, we performed intracerebroventricular (ICV) IGF-1 gene therapy on aged female rats and evaluated its effect on Caudate-Putamen unit (CPu) gene expression and inflammatory state. IGF-1 gene therapy modified senescent microglia of the CPu towards an anti-inflammatory state increasing the proportion of Iba1<jats:sup>+</jats:sup>Arg1<jats:sup>+</jats:sup> cells. Moreover, IGF-1 gene therapy was able to regulate the pro-inflammatory environment of CPu in female aged rats by down-regulating the expression of genes typically over-expressed during aging. Our results demonstrate that, ICV IGF-1 gene therapy, is capable to modulate microglia cells and CPu gene expression, leading to an improvement in motor function.