Pyroptosis is a type of regulated cell death executed by gasdermin family members. However, how gasdermin-mediated pyroptosis is negatively regulated remains unclear. Here, we demonstrate that mannose, a hexose, inhibits GSDME-mediated pyroptosis by activating AMP-activated protein kinase (AMPK). Mechanistically, mannose metabolism in the hexosamine biosynthetic pathway increases levels of the metabolite N-acetylglucosamine-6-phosphate (GlcNAc-6P), which binds AMPK to facilitate AMPK phosphorylation by LKB1. Activated AMPK then phosphorylates GSDME at Thr6, which leads to blockade of caspase-3-induced GSDME cleavage, thereby repressing pyroptosis. The regulatory role of AMPK-mediated GSDME phosphorylation was further confirmed in AMPK knockout and GSDMET6E or GSDMET6A knock-in mice. In mouse primary cancer models, mannose administration suppressed pyroptosis in small intestine and kidney to alleviate cisplatin- or oxaliplatin-induced tissue toxicity without impairing antitumor effects. The protective effect of mannose was also verified in a small group of patients with gastrointestinal cancer who received normal chemotherapy. Our study reveals a novel mechanism whereby mannose antagonizes GSDME-mediated pyroptosis through GlcNAc-6P-mediated activation of AMPK, and suggests the utility of mannose supplementation in alleviating chemotherapy-induced side effects in clinic applications.

Aim: Neurosyphilis patients exhibited significant expression of long noncoding RNA (lncRNA) in peripheral blood T lymphocytes. In this study, we further clarified the role of lncRNA- ENST00000421645 in the pathogenic mechanism of neurosyphilis. Methods: lncRNA- ENST00000421645 was transfected into Jurkat-E6-1 cells, namely lentivirus (Lv)-1645 cells. RNA pull-down assay, flow cytometry, RT-qPCR, ELISA (Neobioscience Technology Co Ltd, Shenzhen, China) and RNA immunoprecipitation chip assay were used to analyze the function of lncRNA- ENST00000421645. Results: The expression of IFN-γ in Lv-1645 cells was significantly increased compared to that in Jurkat-E6-1 cells stimulated by phorbol-12-myristate-13-acetate (PMA). Then, it was suggested that lncRNA- ENST00000421645 interacts with PCM1 protein. Silencing PCM1 significantly increased the level of IFN-γ in Lv-1645 cells stimulated by PMA. Conclusion: This study revealed that lncRNA- ENST00000421645 mediates the production of IFN-γ by sponging PCM1 protein after PMA stimulation.

BackgroundGlycolysis is a critical pathway in cellular glucose metabolism that provides energy and participates in immune responses. However, whether glycolysis is involved in NOD‐like receptor family protein 3 (NLRP3) inflammasome activation and phagocytosis of macrophages in response to Treponema pallidum infection remains unclear.ObjectivesTo investigate the role of glycolysis in activating the NLRP3 inflammasome for regulating phagocytosis in macrophages in response to T. pallidum protein Tp47 and its associated mechanisms.MethodsInteractions between activation of the NLRP3 inflammasome and phagocytosis and the role of glycolysis in Tp47‐treated macrophages were investigated through experiments on peritoneal macrophages and human monocytic cell line‐derived macrophages.ResultsActivation of phagocytosis and NLRP3 inflammasome were observed in Tp47‐treated macrophages. Treatment with NLRP3 inhibitor MCC950 or si‐NLRP3 attenuated Tp47‐induced phagocytosis. Glycolysis and glycolytic capacity were enhanced by Tp47 stimulation in macrophages, and a change in the levels of glycolytic metabolites (phosphoenolpyruvate, citrate and lactate) was induced by Tp47 in macrophages. Inhibition of glycolysis with 2‐deoxy‐D‐glucose, a glycolysis inhibitor, decreased the activation of NLRP3. Expression of M2 isoform of pyruvate kinase (PKM2), an enzyme catalysing a rate‐limiting reaction in the glycolytic pathway, was upregulated in Tp47‐stimulated macrophages. Inhibition of PKM2 with shikonin or si‐PKM2 decreased glycolysis and NLRP3 activation.ConclusionTp47 promotes phagocytosis in macrophages by activating the NLRP3 inflammasome, which is induced by the enhancement of PKM2‐dependent glycolysis.

Background Pathological angiogenesis is an important manifestation of syphilis, but the underlying mechanism of Treponema pallidum subspecies pallidum (T. pallidum)‐induced angiogenesis is poorly understood. Objectives The objective of this study is to investigate the role and related mechanism of the T. pallidum membrane protein Tp47 in angiogenesis. Methods The proangiogenic activity of recombinant T. pallidum membrane protein Tp47 in human umbilical vein endothelial cells (HUVECs) was assessed by tube formation assay, three‐dimensional angiogenesis analysis and experiments with a zebrafish embryo model. The effects of mitochondrial ROS and NADPH oxidase on intracellular ROS induced by Tp47 were further investigated. Furthermore, the levels of autophagy‐related proteins and autophagic flux were measured. Finally, the role of ROS‐induced autophagy in angiogenesis was studied. Results Tp47 promoted tubule formation and the formation of angiogenic sprouts in vitro. In addition, a significant increase in the number of subintestinal vessel branch points in zebrafish injected with Tp47 was observed using a zebrafish embryo model. Tp47 also significantly increased intracellular ROS levels in a dose‐dependent manner. Tp47‐induced tube formation and angiogenic sprout formation were effectively prevented by the ROS inhibitor NAC. In addition, Tp47 enhanced the production of mitochondrial ROS and expression of the NADPH oxidase‐related proteins Nox2 and Nox4. The production of mitochondrial ROS and intracellular ROS was reduced by the NADPH oxidase inhibitors DPI and apocynin. Furthermore, Tp47 significantly increased expression of the autophagy‐related proteins P62 and Beclin 1 and the LC3‐II/LC3‐I ratio and promoted an increase in autophagic flux, which could be effectively rescued by coincubation with the ROS inhibitor NAC. Further intervention with the autophagy inhibitor BafA1 significantly inhibited tube formation and angiogenic sprout formation. Conclusions Tp47‐induced NADPH oxidase enhanced intracellular ROS production via mitochondrial ROS and promoted angiogenesis through autophagy mediated by ROS. These findings may contribute to our understanding of pathological angiogenesis in syphilis.