Vitamin K3 Suppresses Pyroptosis in THP-1 Cells through Inhibition of NF-κB and JNK Signaling Pathways.

Vitamin K, a necessary nutritional supplement for human, has been found to exhibit anti-inflammatory activity. In the present study, we investigated the effects of vitamin K family on lipopolysaccharide (LPS) plus nigericin induced pyroptosis and explored the underlying mechanism of its action in THP-1 monocytes. Results showed that vitamin K3 treatment significantly suppressed THP-1 pyroptosis, but not vitamin K1 or K2, as evidenced by increased cell viability, reduced cellular lactate dehydrogenase (LDH) release and improved cell morphology. Vitamin K3 inhibited NLRP3 expression, caspase-1 activation, GSDMD cleavage and interleukin (IL)-1ß secretion in pyrophoric THP-1 cells. In addition, vitamin K3 inhibited the pro-inflammatory signaling pathways including nuclear factor-κB (NF-κB) and c-Jun N-terminal kinase (JNK). Vitamin K3 treatment also attenuated tissue damage and reduced serum LDH, IL-1ß and IL-6 levels in LPS-induced systemic inflammation of mice. The reduced myeloperoxidase (MPO) activityand F4/80 expression indicated that vitamin K3 effectively reduced the infiltration of neutrophils and macrophages. Moreover, NLRP3 expression in monocytes/macrophages were also decreased in vitamin K3-treatedmice after LPS challenge. These findings suggest that vitamin K3 potently alleviates systemic inflammation and organ injury via inhibition of pyroptosis in monocytes and may serve as a novel therapeutic strategy for patients with inflammatory diseases.

Asiatic acid protests against myocardial ischemia/reperfusion injury via modulation of glycometabolism in rat cardiomyocyte.

BACKGROUND: Asiatic 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 METHODS: The 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-3ß 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. RESULTS: Asiatic 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-3ß 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. CONCLUSION: These 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.

Asiatic acid suppresses neuroinflammation in BV2 microglia via modulation of the Sirt1/NF-κB signaling pathway.

Asiatic acid, a triterpenoid derived from Centella asiatica, has been found to exhibit multiple bioactivities. In this study, we investigated the effects of asiatic acid on lipopolysaccharide (LPS)-induced neuroinflammation and explored the mechanism of its action in BV2 microglia. We found that asiatic acid (0.1 to 100 µM) treatment significantly attenuated nitric oxide (NO) production and inhibited inducible nitric oxide synthase (iNOS) expression in a concentration-dependent manner following LPS exposure. Asiatic acid reduced LPS-induced expression and secretion of inflammatory cytokines, including tumor necrosis factor-α (TNF-α), interleukin-1ß (IL-1ß) and interleukin-6 (IL-6) in BV2 cells. In addition, asiatic acid enhanced Sirt1 expression, reduced NF-κB p65 acetylation, and suppressed NF-κB activation after LPS stimulation. However, EX-527, an inhibitor of Sirt1, abolished the inhibitory effects of asiatic acid on LPS-stimulated microglia activation. These findings suggest that asiatic acid prevents LPS-induced neuroinflammation via regulating the Sirt1/NF-κB signaling pathway.

Asiatic Acid Attenuates Myocardial Ischemia/Reperfusion Injury via Akt/GSK-3ß/HIF-1α Signaling in Rat H9c2 Cardiomyocytes.

Myocardial ischemic/reperfusion injury results from severe impairment of coronary blood supply and leads to irreversible cell death, with limited therapeutic possibilities. Asiatic acid is a pentacyclic triterpenoid derived from the tropical medicinal plant Centella asiatica and serves a variety of bioactivities. In this study, we determined the effect of asiatic acid on myocardial ischemia/reperfusion injury and investigated the underlying mechanisms, using an in vitro rat H9c2 cardiomyocytes model of oxygen-glucose deprivation/reoxygenation (OGD/R) injury. Results showed that pre-treatment with asiatic acid significantly augmented cell viability and prevented lactate dehydrogenase (LDH) release in a concentration-dependent manner after OGD/R exposure. Asiatic acid at 10 µM effectively inhibited apoptotic cell death, suppressed the activities of caspase-3 and caspase-9, and reversed Bax/Bcl-2 ratio in hypoxic H9c2 cells. In addition, asiatic acid improved mitochondrial function, as evidenced by reduced reactive oxygen species (ROS) accumulation, enhanced mitochondrial membrane potential and decreased intracellular calcium concentration. Using Western blot assay, we found that asiatic acid promoted the phosphorylation of Akt and subsequent inactivation of glycogen synthase kinase-3ß (GSK-3ß), and induced the expression of hypoxia-inducible factor 1α (HIF-1α) after OGD/R. The cardioprotective effects of asiatic acid were attenuated by the Akt or HIF-1α inhibitor. Taken together, these data suggested that asiatic acid exerted protective effects against OGD/R-induced apoptosis in cardiomyocytes, at least partly via the Akt/GSK-3ß/HIF-1α pathway.

Effects of maslinic acid, a natural triterpene, on glycogen metabolism in cultured cortical astrocytes.

Maslinic acid (2- alpha,3- beta-dihydroxyolean-12-en-28-oic acid) is a triterpenoid compound present in plants of Olea europaea. In the present study, we investigated the effect of maslinic acid on astrocytic glycogen metabolism. Glycogen phosphorylase (GP) activity in homogenates of cultured astrocytes was analyzed, and maslinic acid exhibited GP inhibition with an IC (50) value of 5.7 microM. Moreover, the influence of maslinic acid on glycogen synthesis and glycogenolysis was also investigated. Pre-incubation with maslinic acid dose-dependently increased cellular glycogen content and prevented the excessive glycogenolysis induced by norepinephrine. In conclusion, maslinic acid is suggested to be a potent inhibitor of astrocytic glycogen phosphorylase.