MGMT deficiency augments STING-mediated inflammatory responses accompanied by metabolic alterations in macrophages.

Abstract

The cGAS-STING pathway senses cytosolic DNA derived from both pathogens and host cells and plays a central role in innate immune responses. O6-methylguanine-DNA methyltransferase (MGMT) is a DNA repair enzyme that removes alkylation-induced DNA lesions and modulates macrophage inflammatory responses. Here, we investigated the role of MGMT in macrophage responses to STING activation. Bone marrow-derived macrophages (BMMs) from Lyz2ΔMgmt mice produced higher levels of IL6, TNFα, and IFNβ following stimulation with the STING agonist DMXAA, accompanied by increased phosphorylation of TBK1 and IRF3. Lyz2ΔMgmt BMMs also exhibited increased expression of CD86, CD40, and CD120a (TNFRI), but reduced MHC class II expression. Metabolic flux analysis revealed enhanced mitochondrial oxidative respiration, increased ATP production, and greater maximal respiratory capacity, whereas glycolytic capacity remained unchanged. In addition, DMXAA-stimulated Lyz2ΔMgmt BMMs displayed increased γH2AX levels and reduced activation of the energy sensor AMPK and autophagy. Transcriptomic analysis further identified enrichment of pathways associated with cellular respiration. Collectively, these findings indicate that MGMT deficiency is associated with enhanced STING-induced inflammatory responses, altered cellular metabolism, and increased DNA damage in macrophages.