Myeloid cell bioenergetics regulate cognitive function in aging

Abstract

AbstractBackgroundA hallmark of aging is the appearance of sustained pro‐inflammatory responses and reduced clearance of pathogenic materials. Systemically, aging is accompanied by a skewing of the immune system towards the myeloid cell lineage and an increase in circulating pro‐ inflammatory factors. In the aging brain, functional degradation of microglia leads to the accumulation of neurotoxic misfolded proteins, a loss of trophic factors that support neurons, and a failure to maintain a homeostatic microenvironment. However, the underlying mechanisms that initiate and sustain maladaptive inflammation with aging are not well defined.MethodTo maintain homeostatic responses, immune cells require robust glycolytic and mitochondrial metabolism to meet demand for energy and biosynthetic precursors. In this study, we investigated metabolic and immune effects of inflammatory prostaglandin E2 (PGE2) signaling in age‐associated inflammation and cognitive decline.ResultWe demonstrate that PGE2 signaling via its EP2 receptor suppresses healthy peripheral myeloid and microglial cell glucose metabolism by driving sequestration of glucose into glycogen through the AKT/GSK3ß/GYS1 pathway and away from generation of ATP. This energy‐deficient state in turn promotes maladaptive, neurotoxic immune responses in vivo. Using genetic and pharmacological modeling, we demonstrate that inhibition of EP2 signaling restores youthful myeloid bioenergetics and immune responses and rescues synaptic mitochondrial function, hippocampal plasticity and spatial memory.ConclusionInhibition of EP2‐dependent disruption of myeloid metabolism may represent a new approach to disorders of aging, with greater specificity than the use of non‐steroidal anti‐inflammatory drugs that target COX‐2 and COX‐1 and suppress both beneficial and toxic prostaglandin signaling pathways.