Immune effects of PI3K/Akt/HIF-1α-regulated glycolysis in polymorphonuclear neutrophils during sepsis

Background Effective removal of pathogenic bacteria is key to improving the prognosis of sepsis. Polymorphonuclear neutrophils (PMNs) are the most important components of innate cellular immunity and play vital roles in clearing pathogenic bacteria. However, the metabolic characteristics and immunomodulatory pathways of PMNs during sepsis have not been investigated. In the present study, we explored the immune metabolism characteristics of PMNs and the mechanism by which neutrophilic glycolysis is regulated during sepsis. Methods Metabolomics analysis was performed on PMNs isolated from 14 septic patients, 26 patients with acute appendicitis, and 19 healthy volunteers. Transcriptome analysis was performed on the PMNs isolated from the healthy volunteers and the patients with sepsis to assess glycolysis and investigate its mechanism. Lipopolysaccharide (LPS) was used to stimulate the neutrophils isolated from the healthy volunteers at different time intervals to build an LPS-tolerant model. Chemotaxis, phagocytosis, lactate production, oxygen consumption rate (OCR), and extracellular acidification rate (ECAR) were evaluated. Results Transcriptomics showed significant changes in glycolysis and the mTOR/HIF-1 alpha signaling pathway during sepsis. Metabolomics revealed that the Warburg effect was significantly altered in the patients with sepsis. We discovered that glycolysis regulated PMNs' chemotaxis and phagocytosis functions during sepsis. Lactate dehydrogenase A (LDHA) downregulation was a key factor in the inhibition of glycolysis in PMNs. This study confirmed that the PI3K/Akt-HIF-1 alpha pathway was involved in the LDHA expression level and also influenced PMNs' chemotaxis and phagocytosis functions. Conclusions The inhibition of glycolysis contributed to neutrophil immunosuppression during sepsis and might be controlled by PI3K/Akt-HIF-1 alpha pathway-mediated LDHA downregulation. Our study provides a scientific theoretical basis for the management and treatment of patients with sepsis and promotes to identify therapeutic target for the improvement of immune function in sepsis.

Automated summary

This study investigated the metabolic characteristics and immunomodulatory pathways of polymorphonuclear neutrophils (PMNs) during sepsis. The study found significant changes in glycolysis and the mTOR/HIF-1 alpha signaling pathway during sepsis. The Warburg effect was also altered in septic patients. Glycolysis was found to regulate PMNs' chemotaxis and phagocytosis functions, and lactate dehydrogenase A (LDHA) downregulation played a key role in inhibiting glycolysis in PMNs. The PI3K/Akt-HIF-1 alpha pathway was involved in LDHA expression and influenced PMNs' chemotaxis and phagocytosis functions.