Abstract 336: Acute Increase In O-GlcNAcylation Reduces The Release Of Cytokines And Attenuates Hypotension In Mice With LPS-induced Sepsis.

Abstract

The attachment of β-O-linked N-Acetylglucosamine (O-GlcNAc) in nuclear and cytoplasmic proteins, known as O-GlcNAcylation, is a common post-translational modification controlled by two enzymes: O-GlcNAc transferase (OGT) and β-N-acetylglucosaminidase (OGA). Acute increases in O-GlcNAc reduce migration of inflammatory cells and the release of pro-inflammatory mediators, important events in sepsis caused by bacterial infection or multiple non-infectious causes. We postulated that acute increases of O-GlcNAc reduce sepsis-associated mortality, release of inflammatory mediators and changes in blood pressure and vascular reactivity. C57BL/6 mice received lipopolysaccharide (LPS) injections to produce mild (LPS M, 10mg/Kg, i.p.) or severe (LPS S, 20mg/Kg, i.p.) sepsis. LPS-treated and naive (N) mice received glucosamine (GlcN), 300mg/Kg, i.v.) or vehicle (30 min before the LPS administration) and were euthanized 6 h later. GlcN treatment augmented O-GlcNAc levels and increased survival in mice with LPS-induced sepsis (LPS M=20%*; LPS S=50%*). GlcN treatment reduced serum levels (pg/mL) of IL-1β [N and N+GlcN = not detected (nd); LPS M = 286.3±14.5*, LPS M+GlcN = 212.9±3.1*#; LPS S= 343.9±29.1*, LPS S+GlcN = 128.4±11*#], IL-6 (N and N+GlcN = nd; LPS M = 448.0±11.5*, LPS M+GlcN = 241.2±11.6*#; LPS S = 508.6±21.7*, LPS S+GlcN = 451.6±8.9*) and TNF-α ((N and N+GlcN = nd; LPS M = 311.3±15.7*, LPS M+GlcN = 76.5±5.5*#; LPS S = 354.2±32.1*, LPS S+GlcN = 136.2±10.2*#) and vascular mRNA expression (2-ΔΔCT) of these cytokines: IL-1β (N and N+GlcN = nd; LPS M = 20.6±1.2*, LPS M+GlcN = 14.0±1.4*#; LPS S = 21.46±1.5*, LPS S+GlcN = 15.87±0.9*#), TNF-α [N and N+GlcN = nd; LPS M = 0.07±0.004*, LPS M+GlcN = 0.02±0.004*#; LPS S = 0.13±0.01*, LPS S+GlcN = 0.02±0.006*#. GlcN treatment attenuated LPS-induced decrease in blood pressure [(mmHg), N = 108±9.0, N+GlcN = 112±10.0; LPS M = 72±6.0*, LPS M+GlcN = 92±8.5*#; LPS S = 59±4.5*, LPS S+GlcN = 88±7.5*# mmHg). No changes in vascular reactivity (thoracic aorta) to phenylephrine or acetylcholine were detected 6 h after LPS administration; (* p<0.05 vs. N; # p<0.05 vs. LPS). In conclusion, O-GlcNAc reduces sepsis-associated inflammatory and cardiovascular events, making this pathway a potential target for therapeutic intervention.