Paeoniflorin inhibited macrophage polarization via glycolysis pathway to protect against sepsis-induced intestinal injury

Sepsis is when the immune reaction to infection results in damage to life-threatening organs. Paeoniflorin is clearly anti-inflammatory. However, whether this compound would have protective effects on the intestine in sepsis by targeting macrophage glycolysis remains unclear. Male C57BL/6 mice were subjected to cecal ligation and puncture (CLP) surgery to induce sepsis. Injections of Paeoniflorin (20 or 40 mg/kg) into the peritoneum were made 6 h afterward. A survival time of 24 h was observed. Serum levels of IL-6, IL-1β and iFABP were determined. Intestinal histology, the expression of tight junction (ZO-1, occludin) and macrophage markers (F4/80, CD86, CD206) were assessed. Tissues of intestine were sequenced for transcriptomics. RAW264.7 macrophages were treated with Paeoniflorin with or without TEPP-46, a PKM2 activator, in vitro and stimulated with LPS. Glycolysis was assessed via ECAR and levels of HK2, PKM2, LDHA. qPCR and western blotting were used for the measurement of polarization markers. The effect of Paeoniflorin and TEPP-46 combined treatment was validated in CLP mice. Paeoniflorin increased 24-hour survival in septic mice, in a dose-dependent way. It decreased the levels of serum IL-6, IL-1β and iFABP, as well as intestinal damage and increased the levels of ZO-1 and occludin. Paeoniflorin decreased the number of M1 macrophages and induced M2 polarization in intestinal tissue. Transcriptomic data indicated that Paeoniflorin rectified the abnormality in glycolysis and gluconeogenesis. Paeoniflorin inhibited glycolysis, lowered the levels of HK2, PKM2 and LDHA, down-regulated M1 genes and up-regulated M2 genes in LPS-treated macrophages. These changes were reversed with TEPP-46. TEPP-46 treated mice completely reversed the protective effects of Paeoniflorin and exacerbated intestinal damage, inflammation, disruption of tight junctions and polarization of M1. Paeoniflorin has anti-injury activity in the intestine in sepsis. It does its job by regulating macrophage glycolysis, maintaining balance between M1/M2 polarization, diminishing systemic inflammation and maintaining intestinal barrier function.