Pyruvate kinase M2 regulates Hif-1α activity and IL-1β induction and is a critical determinant of the warburg effect in LPS-activated macrophages.

Macrophages activated by the TLR4 agonist LPS undergo dramatic changes in their metabolic activity. We here show that LPS induces expression of the key metabolic regulator Pyruvate Kinase M2 (PKM2). Activation of PKM2 using two well-characterized small molecules, DASA-58 and TEPP-46, inhibited LPS-induced Hif-1α and IL-1β, as well as the expression of a range of other Hif-1α-dependent genes. Activation of PKM2 attenuated an LPS-induced proinflammatory M1 macrophage phenotype while promoting traits typical of an M2 macrophage. We show that LPS-induced PKM2 enters into a complex with Hif-1α, which can directly bind to the IL-1β promoter, an event that is inhibited by activation of PKM2. Both compounds inhibited LPS-induced glycolytic reprogramming and succinate production. Finally, activation of PKM2 by TEPP-46 in vivo inhibited LPS and Salmonella typhimurium-induced IL-1β production, while boosting production of IL-10. PKM2 is therefore a critical determinant of macrophage activation by LPS, promoting the inflammatory response.

Palsson-McDermott EM ，Curtis AM ，Goel G ，Lauterbach MA ，Sheedy FJ ，Gleeson LE ，van den Bosch MW ，Quinn SR ，Domingo-Fernandez R ，Johnston DG ，Jiang JK ，Israelsen WJ ，Keane J ，Thomas C ，Clish C ，Vander Heiden M ，Xavier RJ ，O'Neill LA ... -  《-》

Norisoboldine Attenuates Sepsis-Induced Acute Lung Injury by Modulating Macrophage Polarization via PKM2/HIF-1α/PGC-1α Pathway.

Chen Q ，Shao X ，He Y ，Lu E ，Zhu L ，Tang W ... -  《-》

Sulforaphane diminishes moonlighting of pyruvate kinase M2 and interleukin 1β expression in M1 (LPS) macrophages.

Murine macrophages activated by the Toll-like receptor 4 agonist lipopolysaccharide (LPS) polarize to the M1 type by inducing proinflammatory marker proteins and changing their energy metabolism to increased aerobic glycolysis and reduced respiration. We here show that the aliphatic isothiocyanate sulforaphane (Sfn) diminishes M1 marker expression (IL-1β, IL-6, TNF-α, iNOS, NO, and ROS) and leads to highly energetic cells characterized by both high glycolytic and high respiratory activity as assessed by extracellular flux analysis. Focusing on a potential connection between high glycolytic activity and low IL-1β expression in M1 (LPS/Sfn) macrophages, we reveal that Sfn impedes the moonlighting function of pyruvate kinase M2 (PKM2) in M1 macrophages. Sfn limits mono/dimerization and nuclear residence of PKM2 accompanied by reduced HIF-1α levels, Stat3 phosphorylation at tyrosine 705, and IL-1β expression while preserving high levels of cytosolic PKM2 tetramer with high glycolytic enzyme activity. Sfn prevents glutathionylation of PKM2 in LPS-stimulated macrophages which may account for the reduced loss of PKM2 tetramer. Overall, we uncover PKM2 as a novel affected hub within the anti-inflammatory activity profile of Sfn.

Bahiraii S ，Brenner M ，Yan F ，Weckwerth W ，Heiss EH ... -  《Frontiers in Immunology》

ω-Alkynyl arachidonic acid promotes anti-inflammatory macrophage M2 polarization against acute myocardial infarction via regulating the cross-talk between PKM2, HIF-1α and iNOS.

Macrophage polarization determines the timing for the switch from the inflammation phase to the inflammation resolution phase after acute myocardial infarction. The aim of the present study was to investigate whether ω-alkynyl arachidonic acid could mitigate the inflammatory lipid mediators in the regulation of macrophage phenotypes and functions with a special regard to myocardial infarction. We initially discovered that ω-alkynyl arachidonic acid selectively suppressed the up-regulation of inducible nitric oxide synthase (iNOS) over cyclooxygenase-2 (COX-2) in LPS-stimulated macrophages. ω-Alkynyl arachidonic acid also reduced the expression of macrophage M1 biomarkers (e.g., TNF-α, CXCL10, iNOS and IL-6) but increased the expression of macrophage M2 biomarkers (e.g., IL-10 and arginase-1) in LPS-stimulated macrophages. Moreover, ω-alkynyl arachidonic acid markedly enhanced the phagocytotic activity of macrophages against fluorescently-labeled beads or apoptotic H9c2 cardiac cells. We further investigated the in vivo cardioprotective activities of ω-alkynyl arachidonic acid in a mouse model of myocardial infarction. ω-Alkynyl arachidonic acid indeed reduced infarct size, cardiac damage and the leakage of myocardial enzymes CK-MB. Mechanistic studies revealed that ω-alkynyl arachidonic acid suppressed the overexpression and nuclear translocation of glycolytic enzyme PKM2 in LPS-stimulated macrophages. Furthermore, co-immunoprecipitation assay suggested that ω-alkynyl arachidonic acid disrupted the interaction between PKM2 and HIF-1α. Consequently, ω-alkynyl arachidonic acid diminished HIF-1α binding to the HRE sequence in iNOS promoter in response to LPS stimulation. Collectively, ω-alkynyl arachidonic acid may promote the anti-inflammatory M2 polarization of macrophages in acute myocardial infarction via regulating the cross-talk between PKM2, HIF-1α and iNOS.

Cheng Y ，Feng Y ，Xia Z ，Li X ，Rong J ... -  《BIOCHIMICA ET BIOPHYSICA ACTA-MOLECULAR AND CELL BIOLOGY OF LIPIDS》

MKP-1 negatively regulates LPS-mediated IL-1β production through p38 activation and HIF-1α expression.

Interleukin 1 beta (IL-1β) is a pro-inflammatory cytokine that plays a major role in inflammatory diseases as well as cancer. The inflammatory response after Toll-like receptor (TLR) 4 activation is tightly regulated through phosphorylation of MAP kinases, including p38 and JNK pathways. The activation of MAP kinases is negatively regulated by MAPK phosphatases (MKPs). MKP-1 preferentially dephosphorylates p38 and JNK. IL-1β is regulated through the activation of MAPK, including p38 as well as several transcription factors. The oxygen-sensitive transcription factor HIF-1α is a known transcription factor for several inflammatory cytokines including IL-1β and IL-6. Here, we report that MKP-1 regulates HIF-1α expression in response to LPS. MKP-1 deficient bone marrow derived macrophages (BMDMs) exhibited increased reactive oxygen species (ROS) production and higher HIF-1α expression. In contrast, the expression of all three isoforms of prolyl hydroxylases (PHDs), which are important in destabilizing HIF-1α through hydroxylation, were significantly decreased in MKP-1 deficient BMDMs. LPS challenge of MKP-1 deficient BMDMs led to a substantial increase in IL-1β production. An inhibitor of HIF-1α significantly decreased LPS mediated IL-1β production both at the transcript and protein levels. Similarly, inhibition of p38 MAP kinase reduced LPS mediated pro-IL-1β and HIF-1α protein levels as well as ROS production in MKP-1 deficient BMDMs. These findings demonstrate a regulatory function for MKP-1 in modulating IL-1β expression through p38 activation, ROS production and HIF-1α expression.

Talwar H ，Bauerfeld C ，Bouhamdan M ，Farshi P ，Liu Y ，Samavati L ... -  《-》