RLR-mediated type I IFN production plays a pivotal role in elevating host immunity for viral clearance and cancer immune surveillance. Here, we report that glycolysis, which is inactivated during RLR activation, serves as a barrier to impede type I IFN production upon RLR activation. RLR-triggered MAVS-RIG-I recognition hijacks hexokinase binding to MAVS, leading to the impairment of hexokinase mitochondria localization and activation. Lactate serves as a key metabolite responsible for glycolysis-mediated RLR signaling inhibition by directly binding to MAVS transmembrane (TM) domain and preventing MAVS aggregation. Notably, lactate restoration reverses increased IFN production caused by lactate deficiency. Using pharmacological and genetic approaches, we show that lactate reduction by lactate dehydrogenase A (LDHA) inactivation heightens type I IFN production to protect mice from viral infection. Our study establishes a critical role of glycolysis-derived lactate in limiting RLR signaling and identifies MAVS as a direct sensor of lactate, which functions to connect energy metabolism and innate immunity.

Objective Mitochondrial biology appears central to many conditions that progress to death but remains poorly characterized following cardiac arrest. Mitochondrial dysfunction in electron transfer and reactive oxidant species (ROS) leakage during ischemia may lead to downstream events including mitochondrial protein oxidation, tyrosine nitrosylation, cytochrome c loss, and eventual death. We sought to better define early fixed alterations in these mitochondrial functions following whole animal cardiac arrest. Methods We used a murine model of 8 minutes of untreated KCl-induced cardiac arrest followed by resuscitation and return of spontaneous circulation (ROSC) to study mitochondrial functions in four groups of animals: (a) after 8 min cardiac arrest (CA8) but no resuscitation, (b) 30 min post-ROSC (R30), (c) 60 min post-ROSC (R60) and in (d) shams. Heart mitochondria were immediately harvested, isolated and stored at −80°C for later spectrophotometric measurements of electron transfer activities and ROS leakage using appropriate substrates and inhibitors. Mitochondrial cytochrome c content and tyrosine nitration were analyzed by western blot and densitometry. Results A significant ROS leakage from Complex I was evident after just 8 min of cardiac arrest (CA8 group, P<0.05), which was followed by a progressive reduction in Complex I electron transfer activity (CA8>R30>R60). In contrast, Complex II and II–III activities appeared more resistant to ischemia at the time points evaluated. Early changes in a ~50 kDa and ~25 kDa protein were observed in tyrosine nitration along with a loss of cytochrome c. Conclusions A relatively “orderly” process of mitochondrial dysfunction progresses during ischemia and reperfusion. Changes in mitochondrial ROS generation and electron transfer from Complex I occur along with tyrosine nitrosylation and loss of cytochrome c; these may represent important new targets for future human therapies.