Impact of Lysine Lactylation as a Post-Translational Regulator of Inflammatory Resolution in Macrophages

Abstract

Inflammation is a coordinated biological defense involving immune, vascular, and cellular responses to pathogenic or metabolic stressors and can be broadly categorized into two phases: initiation and resolution. While acute inflammation eliminates harmful stimuli, the resolution phase is an active, tightly regulated process required to restore tissue homeostasis. Failure of this transition underlies chronic inflammatory diseases, highlighting the need to define molecular mechanisms governing the shift from inflammatory activation to resolution. During inflammatory challenges, macrophages undergo profound metabolic reprogramming, including a glycolytic switch that increases lactate production. Once considered a metabolic waste product, lactate is now recognized as an immunometabolic signal that regulates cellular function via lysine lactylation (Kla) of histone and non-histone proteins. Although Kla has been primarily studied in cancer as a regulator of oncogenic and immunosuppressive pathways, global lactylome studies reveal it as a conserved and widespread post-translational modification, highlighting the need to explore its role in inflammation. We hypothesized that Kla functions as a metabolically responsive post-translational modification that promotes inflammatory resolution by coordinating protein networks. Using bone marrow-derived macrophages under basal and inflammatory conditions, combined with metabolic perturbations, we employed temporal and intervention studies alongside integrated proteomics to characterize the macrophage lactylome. Our findings demonstrate that Kla is dynamically induced during the transition from pro-inflammatory to pro-resolving states, with its timing closely aligned to the resolution window. Proteomic analyses revealed diverse lactylated proteins, including metabolic enzymes, inflammatory regulators, and stress-response factors, with aconitate decarboxylase (ACOD1), which converts cis-aconitate to the anti-inflammatory metabolite itaconate, consistently identified and validated as a lactylated target. In conclusion, Kla is a metabolically responsive modification that dynamically regulates macrophage protein networks during inflammation and resolution, linking lactate availability to coordinated changes in protein function and highlighting Kla as a potential therapeutic target for restoring immune homeostasis in chronic inflammatory diseases.