Kun Yang
Postdoctoral fellow
East Tennessee State University
Johnson City, Tennessee, United States
Disclosure information not submitted.
Min Fan
Postdoctoral fellow
East Tennessee State University, United States
Disclosure information not submitted.
Xiaohui Wang
Assistant Professor
East Tennessee State University, United States
Disclosure information not submitted.
Jingjing xu
Physician
East Tennessee State University, United States
Disclosure information not submitted.
Tuanzhu Ha
Research Faculty
East Tennessee State University, United States
Disclosure information not submitted.
David Williams
Professor
East Tennessee State University, United States
Disclosure information not submitted.
Chuanfu Li
Professor
East Tennessee State University
6, United States
Disclosure information not submitted.
Title: Lactate promotes HMGB1 lactylation and release via exosome secretion in macrophages in sepsis.
Introduction: High serum lactate and HMGB1 levels are associated with severity and mortality of sepsis. In this study, we investigated whether lactate regulates HMGB1 release via exosome secretion in macrophages during sepsis. We also examined the effect of HMGB1 containing exosomes on endothelial cell permeability.
Methods: Polymicrobial sepsis was induced by cecal ligation and puncture (CLP). To inhibit lactate production, sodium oxamate (OXA, 0.5g/kg body weight) was injected i.p. 3 hours prior to CLP. To enhance serum levels of lactate, lactic acid (0.5g/kg body weight) was injected i.p. 6 hours after CLP. Twenty-four hours later, serum exosomal HMGB1 levels were assessed. We also performed in vitro experiments using macrophages to investigate how lactate induces HMGB1 lactylation. We also examined the effect of macrophage HMGB1 containing exosomes on endothelial cell permeability.
Results: Polymicrobial sepsis significantly increased serum levels of lactate and HMGB1. Suppression of lactate production by Oxamate significantly decreased serum levels of lactate and exosomal HMGB1 and increased survival rate of polymicrobial septic mice 57.7%. In contrast, administration of supplemental lactate markedly enhanced exosomal HMGB1 levels by 180% and increased mortality rate of septic mice by 74%. In vitro results showed that inhibition of lactate production by Oxamate markedly attenuated LPS promoted HMGB1 lactylation and exosomal HMGB1 levels. In contrast, treatment of macrophages with lactate (10 mM) significantly promotes HMGB1 lactylation and increased exosomal HMGB1 levels in macrophages. We demonstrated that activation of lysine acetylase CBP/p300 is required to catalyze the transfer of a lactyl group to HMGB1. Inhibition of monocarboxylate transporters (MCTs) significantly attenuated lactate induced HMGB1 lactylation in macrophages. Treatment of endothelial cells with macrophages HMGB1 containing exosomes significantly increased permeability by decreasing adherens and tight junction proteins.
Conclusion: Our results demonstrated a novel role of lactate in promoting macrophage HMGB1 lactylation and release via exosome secretion in macrophages during polymicrobial sepsis. Lactate/lactate-associated signaling could be the targets for the treatment of sepsis patients.