Targeting glycolysis for neuroprotection in early LPS-induced neuroinflammation

Abstract

Neuroinflammation is a pathophysiological feature of numerous neurological and psychiatric disorders. The immune response in the central nervous system, driven by microglia and astrocytes, leads to metabolic reprogramming towards aerobic glycolysis, a phenomenon known as the Warburg effect. The control of metabolic reprogramming via immunomodulation may represent a potential therapeutic target for providing protection against neuroinflammation, which contributes to neuronal dysfunction and death in several neurological disorders. For this purpose, we investigated putative neuroprotective effects of the downregulation of aerobic glycolysis using the 3PO inhibitor, and the downregulation of neuroinflammation using MCC950, in the early LPS-induced neuroinflammation model. The LPS-induced shift towards glycolysis, inflammatory and glial changes (IL-1β, NF-κB, COX2, Iba1, GFAP) were reversed by 3PO, which improved animal behavior. Additionally, MCC950 (an NLRP3 inhibitor) downregulated TLR4/Akt/p38 MAPK/NF-κB/STAT3 signaling, expressions of COX2 and IL-1β, and the astrocyte reactivity (decreasing GFAP) induced by early neuroinflammation, resulting in low glucose uptake. Our data support the occurrence of the Warburg effect during early neuroinflammation and suggest potential new approaches for the treatment of brain injury, given the role of neuroinflammation in such events. Graphcal abstract : Control of glycolysis as a potential strategie for modulating the neuroimmunometabolism response in early lipopolysaccharide model . Neuroinflammation was induced by the immunostimulating agent lipopolysaccharide (LPS, ip) and the inhibitors 3-(3-Pyridinyl)-1-(4-pyridinyl)-2-propen-1-one (3PO) and MCC950 was administrated intracerebroventricularly (icv). LPS induces neuroinflammation response (1) via Toll-like receptor 4 (TLR4) activation which triggers phosphorylation cascade of the enzymes p38 mitogen-activated protein kinase (p38 MAPK), protein kinase B (Akt) and extracellular signal-regulated kinase (Erk), as well as phosphorylation of the nuclear transcriptional factor kappa B (NF-κB), the expression of the nuclear factors Signal transducer and activator of transcription 3 (STAT3) and Nucleotide-binding domain and leucine-rich repeat protein 3 (NLRP3), and, consequently, increases the expression of pro-inflammatory mediators, such as cyclooxygenase 2(COX2), Ionized Calcium-Binding Adapter Molecule 1(Iba1), Interleukin 1 beta (IL-1β ). LPS promotes astrocytic response by increasing the content of glial fibrillary acidic protein (GFAP) and the secretion of calcium-binding protein (S100B) (2). The neuroimmune response is followed by oxidative stress, reducing the antioxidant defense and increasing oxidative damage (3). Furthermore, the neuroinflammation response shifts the neuroimmunometabolism by directing energy metabolism towards aerobic glycolysis (4). LPS increases glucose uptake, the activity of the glycolytic enzymes 6-phosphofructo-1-kinase (PFK1) and pyruvate kinase (PK), and lactate content in CSF. The high glucose consumption is independent of mitochondrial activity. The 3PO, an inhibitor of the PFKFB3 enzyme, downmodulates the glycolytic flux during the early neuroinflammatory response. 3PO reverses the effects of LPS on glucose uptake, glycolytic enzymes activity, PFK1 and PK, and the phosphorylation of p38 MAPK. 3PO by reducing energy flow for aerobic glycolysis decreases the neuroinflammation response. The compound MCC950, an inhibitor of NLRP3 inflammasome assembly, reverses the neuroinflammatory signaling and the oxidative stress induced by LPS. MCC950 partially reverses the neuroimmunometabolism change by reducing only glucose uptake. • Neuroinflammation promotes metabolic reprogramming and increases glycolytic flow • 3PO downmodulates the neuroimmunometabolic shift towards glycolysis • The glycolytic pathway is a potential target for new anti-inflammatory strategies • Inhibition of NLRP3 reverses the neuroinflammation and glucose uptake

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