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BackgroundAMP-activated protein kinase (AMPK) is an important enzyme in regulation of cellular energy homeostasis. We have previously shown that AMPK activation by 5-aminoimidazole-4-carboxamide (AICAR) results in suppression of immune responses, indicating the pivotal role of AMPK in immune regulation. However, the cellular mechanism underpinning AMPK inhibition on immune response remains largely to be elucidated. The study aimed to investigate the effects of AMPK inhibition on reactive oxygen species (ROS)-nuclear factor κB (NFκB) signaling and endotoxemia-induced liver injury.Methodology/Principal FindingsRAW 264.7 cells were pretreated with AMPK activator or inhibitor, followed by LPS challenge. In addition, LPS was injected intraperitoneally into mice to induce systemic inflammation. The parameters of liver injury and immune responses were determined, and survival of mice was monitored respectively. LPS challenge in RAW 264.7 cells resulted in AMPK activation which was then inhibited by compound C treatment. Both AMPK activation by AICAR or inhibition by compound C diminished LPS-induced ROS generation, inhibited phosphorylation of IKK, IκB, and NFκB p65, and consequently, decreased TNF production of RAW 264.7 cells. AICAR or compound C treatment decreased ALT, AST, and TNF levels in serum, reduced CD68 expression and MPO activity in liver tissue of mice with endotoxemia. Moreover, AICAR or compound C treatment improved survival of endotoxemic mice.ConclusionsAICAR or compound C treatment attenuates LPS-induced ROS-NFκB signaling, immune responses and liver injury. Strategies to activate or inhibit AMPK signaling may provide alternatives to the current clinical approaches to inhibit immune responses of endotoxemia.

IntroductionCellular senescence is a hallmark of tumors and has potential for cancer therapy. Cellular senescence of tumor cells plays a role in tumor progression, and patient prognosis is related to the tumor microenvironment (TME). This study aimed to explore the predictive value of senescence-related genes in thyroid cancer (THCA) and their relationship with the TME.MethodsSenescence-related genes were identified from the Molecular Signatures Database and used to conduct consensus clustering across TCGA-THCA. Differentially expressed genes (DEGs) were identified between the clusters used to perform multivariate Cox regression and least absolute shrinkage and selection operator regression (LASSO) analyses to construct a senescence-related signature. TCGA dataset was randomly divided into training and test datasets to verify the prognostic ability of the signature. Subsequently, the immune cell infiltration pattern, immunotherapy response, and drug sensitivity of the two subtypes were analyzed. Finally, the expression of signature genes was detected across TCGA-THCA and GSE33630 datasets, and further validated by RT-qPCR.ResultsThree senescence clusters were identified based on the expression of 432 senescence-related genes. Then, 23 prognostic DEGs were identified in TCGA dataset. The signature, composed of six genes, showed a significant relationship with survival, immune cell infiltration, clinical characteristics, immune checkpoints, immunotherapy response, and drug sensitivity. Low-risk THCA shows a better prognosis and higher immunotherapy response than high-risk THCA. A nomogram with perfect stability constructed using signature and clinical characteristics can predict the survival of each patient. The validation part demonstrated that ADAMTSL4, DOCK6, FAM111B, and SEMA6B were expressed at higher levels in the tumor tissue, whereas lower expression of MRPS10 and PSMB7 was observed.DiscussionIn conclusion, the senescence-related signature is a promising biomarker for predicting the outcome of THCA and has the potential to guide immunotherapy.