The Role of Lactylation in Mental Illness: Emphasis on Microglia

A paradigm shift is currently taking place in the etiopathogenesis of neuropsychiatric disorders as immunometabolism is replacing the earlier neurotransmitter model. According to the new concept, cellular bioenergetics drives information processing in the central nervous system; therefore, neuropathology is conceptualized as a direct consequence of impaired metabolism. Along the same lines, endoplasmic reticulum stress and gut barrier dysfunction are emerging as novel targets in schizophrenia and affective disorders, linking immune responses to cellular distress. Furthermore, microglia, the brain’s innate immune cells, acquire energy through oxidative phosphorylation, while in the resting state, and glycolysis upon activation, contributing to lactate accumulation and reduced brain pH. The same metabolic signature characterizes neuropsychiatric disorders as the central nervous system derives adenosine triphosphate from aerobic glycolysis, upregulating lactate and generating an acidic environment. Although known for over three decades, the link between dysmetabolism and neuropathology was poorly defined until the discovery of brain-resident innate lymphoid cells, including natural killer cells, and lactylation of histone and nonhistone proteins. In this perspective article, we examine three anti-inflammatory microglial systems relevant for neuropsychiatry: lactate, oxytocin, and the aryl hydrocarbon receptor. We also discuss potential interventions for restoring microglial homeostasis.