Background Protein kinase R (PKR) is implicated in the inflammatory response to bacterial infection while the role of PKR in sepsis-induced acute kidney injury (AKI) is largely unknown. This study aimed to investigate the effects of the specific PKR inhibitor C16 (C13H8N4OS) on lipopolysaccharide (LPS)-induced AKI, and its mechanisms of action. Material/Methods C57BL/6J mice were injected intraperitoneally with C16 or vehicle 1 h before the LPS challenge and then injected intraperitoneally with LPS or 0.9% saline. After the LPS challenge, histopathological damage, renal function, and levels of proinflammatory cytokines were assessed. All the related signaling pathways were analyzed. Results C16 effectively inhibited LPS-induced renal elevation of proinflammatory cytokines and chemokines. C16 prevented NF-κB activation and suppressed the PKR/eIF2α signaling pathway in AKI after the LPS challenge. Furthermore, C16 significantly inhibited pyroptosis during AKI, as evidenced by decreased renal levels of apoptosis-associated speck-like protein; NACHT, LRR, NLR Family Pyrin Domain-Containing 3; caspase-1; interleukin (IL)-1β; and IL-18. Conclusions Our findings suggest that inhibition by C16 ameliorated LPS-induced renal inflammation and injury, at least partly through modulation of the pyroptosis signal pathway in the kidney.

BackgroundAsiatic acid is a reported glycogen phosphorylase inhibitor derived from the tropical medicinal plant Centella asiatica and exhibits myocardial protection both in vivo and in vitro. The purpose of this study was to evaluate the effects of asiatic acid on myocardial ischemia/reperfusion (MI/R) injury and investigate the underlying mechanisms associated with the modulation of glycometabolism in cardiomyocyte.Materials and methodsThe rats were subjected to MI/R with or without asiatic acid pretreatment. The cardiac function indexes, the size of myocardial infarction, and plasma lactate dehydrogenase (LDH) and creatine kinase (CK) activities were detected. Cardiomyocyte apoptosis was analyzed by TUNEL assay. The Akt/GSK-3β activation was measured by Western blot. The glycogen content, plasma glucose and lactate concentrations were determined following MI/R. The mRNA and protein levels of PPARγ and GLUT4 were determined by real-time PCR and Western blot, respectively.ResultsAsiatic acid pretreatment significantly improved the cardiac function indexes, attenuated the size of myocardial infarction, reduced LDH and CK activities, and suppressed cardiomyocyte apoptosis after MI/R. Asiatic acid activated Akt/GSK-3β signal pathway in the myocardium following MI/R injury. In addition, asiatic acid effectively suppressed MI/R-induced glycogen breakdown and inhibited the elevation of plasma glucose and lactate concentrations. Asiatic acid treatment increased PPARγ expression at both mRNA and protein levels, and promoted the translocation of GLUT4 to plasma membrane after MI/R insult. However, the effects mediated by asiatic acid on glycometabolism and GLUT4 translocation were reversed by the administration of LY294002, the Akt inhibitor.ConclusionThese findings demonstrated that asiatic acid exerts beneficial effects on MI/R injury in rats. This protection may be related to the modulation of glycometabolism via Akt-dependent GLUT4 translocation and PPARγ activation in ischemic cardiomyocyte.

Objectives This study was designed to investigate the effects and the mechanism of Tanshinone IIA (TIIA) on endotoxic shock-induced lung injury in a mouse model. Methods Mice were administered intraperitoneally with TIIA (10 mg/kg) 0.5 h before lipopolysaccharide (LPS) challenge and then received additional injections every 24 h during the 3-day experimental period. The physiological indexes, the survival rate and the parameters for lung injury were examined. The protein levels of Sirt1, and the acetylation and activation of NF-jB p65 were determined. The expression and secretion of pro-inflammatory factors were evaluated, respectively. Key findings Treatment with TIIA significantly improved physiological indexes and increased the survival rate of mice in response to LPS challenge. TIIA treatment displayed an obvious up-regulation of Sirt1 protein, in accompany with reduced acetylation and activation of NF-jB p65 following LPS stimulation. In addition, TIIA attenuated LPS-induced lung injury and prevented the expression and secretion of pro-inflammatory factors. However, the protective effects of TIIA were abolished by Sirt1 inhibitor. Conclusions Tanshinone IIA prevents LPS-induced secretion of pro-inflammatory cytokines thus exerts protective effects against acute lung injury, probably via modulation of Sirt1/NF-jB signalling pathway.

Brain-type glycogen phosphorylase (pygb) is one of the rate-limiting enzymes in glycogenolysis that plays a crucial role in the pathogenesis of type 2 diabetes mellitus. Here we investigated the role of pygb in high-glucose (HG)-induced cardiomyocyte apoptosis and explored the underlying mechanisms, by using the specific pygb inhibitors or pygb siRNA. Our results show that inhibition of pygb significantly attenuates cell apoptosis and oxidative stress induced by HG in H9c2 cardiomyocytes. Inhibition of pygb improved glucose metabolism in cardiacmyocytes, as evidenced by increased glycogen content, glucose consumption, and glucose transport. Mechanistically, pygb inhibition activates the Akt–GSK-3β signaling pathway and suppresses the activation of NF-κB in H9c2 cells exposed to HG. Additionally, pygb inhibition promotes the expression and the translocation of hypoxia-inducible factor-1α (HIF-1α) after HG stimulation. However, the changes in glucose metabolism and HIF-1α activation mediated by pygb inhibition are significantly reversed in the presence of the Akt inhibitor MK2206. In conclusion, this study found that inhibition of pygb prevents HG-induced cardiomyocyte apoptosis via activation of Akt–HIF-α.

Damage-associated molecular patterns (DAMPs) are the primary promoter of progressive neuroinflammation and are associated with chronic stress-related emotional disorders. The present study investigated the role and mechanism of extracellular nucleosomes and histones, the newly defined DAMPs, in mice with chronic stress. C57BL/6 mice were exposed to chronic unpredictable mild stress (CUMS) and corticosterone drinking, respectively, for 4 weeks. Negative emotional behaviors were comprehensively investigated. Microglial morphology, oxidative stress, and inflammation, as well as C-type lectin receptor 2D (Clec2d) and Toll-like receptor 9 (TLR9) expression in medial prefrontal cortex (mPFC) were assessed with flow cytometer and cell sorting. Specifically, microglial pro-inflammatory activation and inflammation were further investigated with stereotactic injection of recombinant nucleosomes and histones in mPFC and further evaluated with AAV-Clec2d knocking-down, DNase I, and activated protein C (APC) pretreatment. Moreover, the rescue effect by AAV-Clec2d knocking-down was observed in mice with chronic stress. Mice with chronic stress were presented as obviously depressive- and anxiety-like behaviors and accompanied with significant microglial oxidative stress and inflammation, indicating by reactive oxygen species (ROS) production, primed nuclear factor-κB (NF-κB) signaling pathway, activated NACHT, LRR, and PYD domain–containing protein 3 (NLRP3) inflammasome, and upregulated Clec2d and TLR9 in mPFC, together with histones dictation in cerebrospinal fluid and extracellular trap formation. Stereotactic injection of nucleosomes was contributed to promote microglial inflammation rather than histones in mPFC, indicating that the pro-inflammatory role was derived from extracellular histones-bound DNA but not freely histones. AAV-Clec2d knocking-down, DNase I, and APC were all effective to inhibit nucleosome-induced microglial oxidative stress and inflammation. Moreover, AAV-Clec2d knocking-down in mice with chronic stress exhibited reduced microglial inflammation and improved negative emotional behaviors. Our findings reveal a novel mechanism of DAMP-associated inflammation that extracellular nucleosomes accelerate microglial inflammation via Clec2d and TLR9, and then contribute to chronic stress-induced emotional disorders.