Glycolytic reprogramming of macrophages activated by NOD1 and TLR4 agonists: No association with proinflammatory cytokine production in normoxia

Abstract

Upon activation with pathogen-associated molecular patterns, metabolism of macrophages and dendritic cells is shifted from oxidative phosphorylation to aerobic glycolysis, which is considered important for proinflammatory cytokine production. Fragments of bacterial peptidoglycan (muramyl peptides) activate innate immune cells through nucleotide-binding oligomerization domain (NOD) 1 and/or NOD2 receptors. Here, we show that NOD1 and NOD2 agonists induce early glycolytic reprogramming of human monocyte-derived macrophages (MDM), which is similar to that induced by the Toll-like receptor 4 (TLR4) agonist lipopolysaccharide. This glycolytic reprogramming depends on Akt kinases, independent of mTOR complex 1 and is efficiently inhibited by 2-deoxy-d-glucose (2-DG) or by glucose starvation. 2-DG inhibits proinflammatory cytokine production by MDM and monocyte-derived dendritic cells activated by NOD1 or TLR4 agonists, except for tumor necrosis factor production by MDM, which is inhibited initially, but augmented 4 h after addition of agonists and later. However, 2-DG exerts these effects by inducing unfolded protein response rather than by inhibiting glycolysis. By contrast, glucose starvation does not cause unfolded protein response and, in normoxic conditions, only marginally affects proinflammatory cytokine production triggered through NOD1 or TLR4. In hypoxia mimicked by treating MDM with oligomycin (a mitochondrial ATP synthase inhibitor), both 2-DG and glucose starvation strongly suppress tumor necrosis factor and interleukin-6 production and compromise cell viability. In summary, the requirement of glycolytic reprogramming for proinflammatory cytokine production in normoxia is not obvious, and effects of 2-DG on cytokine responses should be interpreted cautiously. In hypoxia, however, glycolysis becomes critical for cytokine production and cell survival.

Mediators of Metabolism: An Unconventional Role for NOD1 and NOD2

“…Different findings were reported in studies examining human monocyte-derived macrophages (MDM) [ 32 , 33 ]. One study demonstrates by RNAi-mediated knockdown that thapsigargin-induced ER stress does not require expression of NOD1 or NOD2, either alone or in combination [ 32 ].…”

“…Instead, their data revealed that MDP induces an UPR that involves all three branches of the ER stress response mediated by interaction of NOD2, RIP2, and laccase domain containing-1 (LACC1) at the ER membrane [ 32 ]. Another study indicates that a bacterial ligand able to stimulate both NOD1 and NOD2 (M-triDAP) does not induce ER stress when added to MDM alone [ 33 ]. Instead, M-triDAP enhanced ER stress induced by 2-deoxy-D-glucose (2-DG) that results in increased pro-inflammatory cytokine production via IRE1α mediated activation of XBP1s and p38 MAPK [ 33 ].…”

“…Another study indicates that a bacterial ligand able to stimulate both NOD1 and NOD2 (M-triDAP) does not induce ER stress when added to MDM alone [ 33 ]. Instead, M-triDAP enhanced ER stress induced by 2-deoxy-D-glucose (2-DG) that results in increased pro-inflammatory cytokine production via IRE1α mediated activation of XBP1s and p38 MAPK [ 33 ]. Taken together, these studies reveal new roles for NOD1 and NOD2 as mediators of ER stress-induced inflammation in macrophages.…”

The role of glycolysis in immune response

“…В базальном состоянии основным источником энергии для макрофагов служит ОФ [5]. В культурах макрофагов мыши и человека уже через 10 мин после добавления агонистов ПРР возрастает скорость закисления внеклеточной среды с выходом на максимум примерно к 60-й минуте [27][28][29][30]. Повышение скорости закисления среды обусловлено ростом секреции лактата вследствие усиления гликолиза и блокируется ингибиторами гликолиза, такими как 2-дезокси-D-глюкоза (2-ДГ) [30,31].…”

“…В культурах макрофагов мыши и человека уже через 10 мин после добавления агонистов ПРР возрастает скорость закисления внеклеточной среды с выходом на максимум примерно к 60-й минуте [27][28][29][30]. Повышение скорости закисления среды обусловлено ростом секреции лактата вследствие усиления гликолиза и блокируется ингибиторами гликолиза, такими как 2-дезокси-D-глюкоза (2-ДГ) [30,31]. Наряду с этим в M1-макрофагах возрастает потребление глюкозы, повышаются внутриклеточные концентрации промежуточных метаболитов гликолиза [2,4,27,29,[32][33][34][35].…”