Selective MIF Enolase Inhibitor TE-91 Regulates M1 Polarization and Associated Metabolic Reprogramming

Macrophage migration inhibitory factor (MIF) has been shown to induce M1 macrophage polarization with oxidative stress and associated metabolic reprogramming. Several tautomerase inhibitors were shown to selectively inhibit either MIF's ketonase or enolase sub-activities. In this study, we aimed to investigate the role of enolase sub-activity in M1 polarization using the selective enolase inhibitor TE-91. We performed in silico molecular docking analysis and physicochemical characterization of TE-91. LPS + IFN-γ-induced RAW264.7 cells were applied as a model for M1 macrophage activation. We performed ROS and nitrite determinations, ELISA, qPCR, and immunoblot analysis, and measured mitochondrial oxygen consumption rate and extracellular acidification rate. Here, we reveal that TE-91 might directly bind to the MIF tautomerase active site. Furthermore, TE-91 reduces M1 activation by enhancing oxidative phosphorylation and reducing the glycolytic activity in LPS + IFN-γ-induced macrophage cells. In the same model, TE-91 reduces TNF-α, IL-6, CCL2, and iNOS mRNA transcription yet fails to modulate PARP1 and SOD2 mRNA transcription. It also decreases ROS, nitrite, and IL-6 production without influencing TNF-α and CCL2 protein production. TE-91 was unable to reduce either HIF-1α mRNA transcription or its protein expression. Finally, TE-91 reduced IL-1β cleavage, without affecting IL-1β protein expression. These results may highlight the importance of tautomerase sub-activities in M1 polarization.