Dryocrassin ABBA ameliorates Streptococcus pneumoniae-induced infection in vitro through inhibiting Streptococcus pneumoniae growth and neutralizing pneumolysin activity.

To explore the role of dryocrassin ABBA (ABBA) in the prevention and treatment of Streptococcus pneumoniae (S. pneumoniae) infections in vitro, a minimal inhibitory concentration test, growth curve assay, hemolysis assay, BacLight LIVE/DEAD staining experiments, oligomerization inhibition assay, time-killing test, LDH release detection assay and cytotoxicity test were performed to evaluate the efficacy of ABBA against S. pneumoniae infections in vitro. The results indicated that ABBA treatment exists bactericidal effect on S. pneumoniae at a concentration of less than 8 µg/ml. Furthermore, ABBA was effective at inhibiting the oligomerization of pneumolysin (PLY) from reducing its hemolytic activity. Meanwhile, ABBA could ameliorate cell injury by neutralizing the biological activity of PLY without cytotoxicity. In summary, ABBA was a leading compound against S. pneumoniae infections through bactericidal effect and neutralizing PLY activity.

Myricetin inhibits the type III secretion system of Salmonella enterica serovar typhimurium by downregulating the Salmonella pathogenic island I gene regulatory pathway.

Based on the in-depth study of type III secretion systems (T3SS) in pathogenic bacteria, approaches targeting T3SS have become new alternative strategies to combat drug-resistant bacterial infections. As an important food-borne pathogen, Salmonella enterica serovar Typhimurium (S. Typhimurium) injects effector proteins into host cells through the T3SS to disrupt cell signaling and host responses. In this study, myricetin was screened for its ability to block the translocation function of effector proteins (SipA/SipB) using cell biology and molecular biology methods. It exerted strong effects on inhibiting the expression of Salmonella pathogenicity island 1 (SPI-1)-associated effector proteins without affecting S. Typhimurium growth and thus prevented S. Typhimurium from invading HeLa cells and ultimately inhibited S. Typhimurium-mediated cell damage. In an animal experiment, myricetin comprehensively protected mice from death and pathological damage. A further analysis of the mechanism of action showed that myricetin interfered with the regulatory network of SPI-1-related genes, resulting in a significant decrease in the levels of key effector proteins, and thus inhibited T3SS-mediated virulence. In summary, this study provides a solution for clinical resistance to S. Typhimurium infection and potential candidate compounds. Myricetin, a potential T3SS inhibitor, possesses effective biological activity and exerts protective effects in vitro and in vivo. Myricetin will likely be developed as a novel type of antibiotic targeting S. Typhimurium infections in the future.

Theaflavin-3,3´-digallate increases the antibacterial activity of ß-lactam antibiotics by inhibiting metallo-ß-lactamase activity.

Metallo-ß-lactamases (MBLs) are some of the best known ß-lactamases produced by common Gram-positive and Gram-negative pathogens and are crucial factors in the rise of bacterial resistance against ß-lactam antibiotics. Although many types of ß-lactamase inhibitors have been successfully developed and used in clinical settings, no MBL inhibitors have been identified to date. Nitrocefin, checkerboard and time-kill assays were used to examine the enzyme behaviour in vitro. Molecular docking calculation, molecular dynamics simulation, calculation of the binding free energy and ligand-residue interaction decomposition were used for mechanistic research. The behaviour of the enzymes in vivo was investigated by a mouse infection experiment. We showed that theaflavin-3,3´-digallate (TFDG), a natural compound lacking antibacterial activities, can inhibit the hydrolysis of MBLs. In the checkerboard and time-kill assays, we observed a synergistic effect of TFDG with ß-lactam antibiotics against methicillin-resistant Staphylococcus aureus BAA1717. Molecular dynamics simulations were used to identify the mechanism of the inhibition of MBLs by TFDG, and we observed that the hydrolysis activity of the MBLs was restricted by the binding of TFDG to Gln242 and Ser369. Furthermore, the combination of TFDG with ß-lactam antibiotics showed effective protection in a mouse Staphylococcus aureus pneumonia model. These findings suggest that TFDG can effectively inhibit the hydrolysis activity of MBLs and enhance the antibacterial activity of ß-lactam antibiotics against pathogens in vitro and in vivo.

Genetic variation of mini- and microsatellites and a clonal structure in Enterocytozoon bieneusi population in foxes and raccoon dogs and population differentiation of the parasite between fur animals and humans.

Enterocytozoon bieneusi is an obligate intracellular protozoan parasite that infects a wide range of mammal hosts and birds. Previous genotypic surveys were limited to measure the polymorphisms at the ribosomal internal transcribed spacer (ITS) that evolved slowly. Data on population structure are available only on E. bieneusi isolates from primates. This study explored the genotypic and phylogenetic characteristics of four mini- and microsatellites and performed a population genetic analysis in 39 E. bieneusi isolates of potentially zoonotic ITS genotype D from farmed foxes and raccoon dogs in China. Sequence polymorphisms facilitated determination of six, two, four, and five genotypes at markers MS1, MS3, MS4, and MS7, respectively. Patterns of phylogeny revealed different levels of diversity within and among the genetic markers. Clear genotypic and phylogenetic divergences between E. bieneusi isolates of ITS genotype D from fur animals and humans were observed at individual markers. Complete linkage disequilibrium and very limited recombination in subsequent population genetic analysis supported a clonal structure for E. bieneusi population from fur animals (FID). Phylogenetic analysis, genetic network, and measures of F ST and gene flow demonstrated population differentiation of FID from two known human E. bieneusi populations HID (with a clonal structure) and HIA (with an epidemic structure). The data indicated an ideal resolving power of MLST compared to the previously widely used ITS genotyping and confirmed the clonal nature and population differentiation of E. bieneusi in various hosts.

The casein-derived peptide YFYPEL alleviates intestinal epithelial cell dysfunction associated with NEC by regulating the PI3K/AKT signaling pathway.

Necrotizing enterocolitis (NEC) is a life-threatening risk to the health of neonates, but thus far, there is no very effective treatment. Although many studies have confirmed the therapeutic role of peptides in diseases, the effect of peptides in NEC remains poorly understood. This study investigated the role of casein-derived peptide YFYPEL in NEC cells and animal models. We synthesized YFYPEL and analysed its protective effects on NEC both in vitro and in vivo. YFYPEL integration in the intestine increased rat survival and clinical conditions, lowered the incidence of NEC, alleviated bowel inflammation, and enhanced intestinal cell migration. Furthermore, YFYPEL significantly decreased interleukin 6 expression and increased intestinal epithelial cell migration. Moreover, YFYPEL alleviated intestinal epithelial cell dysfunction through the PI3K/AKT pathway, as demonstrated by western blotting and bioinformatics analysis. A selective PI3K activator reversed the protective effect of YFYPEL on lipopolysaccharide-stimulated intestinal epithelial cells. Our study showed that YFYPEL reduced inflammatory cytokine expression and enhanced migration by regulating the PI3K/AKT pathway. The use of YFYPEL may thus develop into a novel modality in NEC treatment.

Metallo-ß-lactamases inhibitor fisetin attenuates meropenem resistance in NDM-1-producing Escherichia coli.

The prevalence and development of New Delhi metallo-ß-lactamase-1 (NDM-1) have led to increases in bacterial resistance to the majority of clinically used antibiotics, including carbapenems. This study attempts to identify a novel inhibitor of NDM-1 for resistant bacteria infection. Herein, we found that fisetin, as an agent, distinctly inhibits the activity of NDM-1 (IC50 = 9.68 µg/mL) through on enzyme activity inhibition screening. Notably, fisetin is a metallo-ß-lactamases inhibitor without the ability to chelate zinc ions, as well as with a significantly inhibitory effect on NDM-9, VIM-1, IMP-1 and KPC-2. The combination of fisetin with meropenem could attenuate meropenem resistance in NDM-1-positive Escherichia coli. The MIC values of combined treatment were lower than those found for meropenem or fisetin alone (FICI from 0.25 ± 0.00 to 0.38 ± 0.00) although fisetin lacks antibacterial activities (MIC＞1024 µg/mL). Furthermore, fisetin combined with meropenem could kill all tested bacteria no more than 3 h in vitro and this synergistic effect could also be observed in vivo. Molecular dynamics simulations revealed that fisetin successfully inhibit the hydrolytic activity of NDM-1. Additionally, the mutation of NDM-1 resulted in a decreased inhibition of NDM-1 activity by fisetin compared with the WT protein. Finally, our results indicate that fisetin is an effective NDM-1 inhibitor, which suggests the combination of this compound with meropenem is a promising strategy for carbapenem-resistant bacterial infection.

LncRNA and mRNA profiles of human milk-derived exosomes and their possible roles in protecting against necrotizing enterocolitis.

Necrotizing enterocolitis (NEC) is one of the most severe diseases commonly afflicting premature infants. Our previous studies suggests that human milk-derived exosomes (HM-Exos) have a potential therapeutic effect on NEC. In this study, we investigate the potentially therapeutic role of HM-Exos in an NEC animal model via comprehensive lncRNA and mRNA expression profiles. A rat model of NEC was induced through hypoxia, hypothermia and formula feeds. We extracted exosomes from the colostrum of healthy lactating mothers and identified their functions in an NEC animal model. Furthermore, high-throughput lncRNA and mRNA sequencings were explored to find the underlying mechanisms. Although both exosomes from term human breast milk (Term-Exos) and exosomes from preterm human breast milk (Pre-Exos) alleviated the severity of NEC, Pre-Exos seemed to better promote the proliferation of intestinal epithelial cells in vivo. We identified a total of 44 differentially expressed lncRNAs and 88 differentially expressed mRNAs between Term-Exos and Pre-Exos. Further GO and KEGG pathway analysis showed that the lncRNA-mRNA network of HM-Exos was associated with the JAK-STAT signaling pathway, bile secretion and the AMPK signaling pathway, which are predicted to be involved in the proliferation of cells. Therefore, this study reveals for the first time the important roles of human milk derived lncRNAs and mRNAs in protecting against necrotizing enterocolitis. These results provide new insight into the development of NEC.

Peptide Tat(48-60) YVEEL protects against necrotizing enterocolitis through inhibition of toll-like receptor 4-mediated signaling in a phosphatidylinositol 3-kinase/AKT dependent manner.

Necrotizing enterocolitis (NEC) is a catastrophic disease largely occurring in preterm infants, and toll-like receptor 4 (TLR4) has been implicated in its pathogenesis. The current therapeutic strategies for NEC are, however, far from optimal. In the present study, a whey-derived antioxidative peptide conjugated with a cell-penetrating TAT [Tat (48-60) YVEEL] was prepared to endow it with enhanced cell uptake capability and bioavailability. The protective effect of Tat (48-60) YVEEL on experimental NEC was evaluated both in vitro and in vivo. Inhibition of TLR4-mediated signaling by Tat (48-60) YVEEL was assessed in FHC and IEC-6 enterocytes, neonatal rat model of NEC, and the mechanism underlying this effect was determined. Tat (48-60) YVEEL significantly inhibited TLR4-mediated expression of pro-inflammatory cytokines, p65 nuclear translocation and restored the impaired enterocyte migration in cultured enterocytes. In addition, Tat (48-60) YVEEL administration strikingly increased the survival rate, and reduced the severity of NEC in rats through inhibition of TLR4-mediated signaling. These protective effects of Tat (48-60) YVEEL occurred in a PI3K/AKT dependent manner, as administration of PI3K activator Ys49 abrogated its protective effects. Combined with liposomes, Tat (48-60) YVEEL demonstrated longer retention in the intestines that better for potential clinical applications. These data demonstrate that Tat (48-60) YVEEL protects against NEC through inhibition of TLR4-mediated signaling in a PI3K/AKT dependent manner, and offer a potential therapeutic approach to this disease.

Farrerol Enhances Nrf2-Mediated Defense Mechanisms against Hydrogen Peroxide-Induced Oxidative Damage in Human Retinal Pigment Epithelial Cells by Activating Akt and MAPK.

Oxidative stress of the retinal pigment epithelium (RPE) is an essential element contributing to the progression of age-related macular degeneration (AMD). Notably, the activation of Nrf2 is regarded as an effective strategy for controlling oxidation. The novel 2,3-dihydroflavonoid compound farrerol, which is extracted from Rhododendron, possesses antioxidant properties. In this study, we investigated the mechanism by which farrerol protects against oxidative damage mediated by hydrogen peroxide (H2O2) in adult retinal pigment epithelial cell line 19 (ARPE-19) cells. Farrerol supplementation conspicuously reversed H2O2-related cell damage through declining the generation of intracellular reactive oxygen species (ROS) and MDA and increasing the concentrations of GSH and SOD. According to the results of the apoptosis assay, a farrerol pretreatment decreased the protein expression of the Bax/Bcl-2, cleaved caspase-3, PARP, caspase-8, and caspase-9 proteins. Furthermore, farrerol markedly activated Nrf2, thereby increasing the levels of antioxidant enzymes downstream of Nrf2, such as HO-1, NQO1, and GCLM. Knockdown of Nrf2 with a specific siRNA successfully suppressed farrerol-mediated HO-1 transcription and partially abolished the cytoprotective effect on ARPE-19 cells. Meanwhile, farrerol induced Akt and MAPK phosphorylation in a dose-related way. However, inhibiting Akt and MAPK substantially blocked the cytoprotective functions of farrerol. Therefore, farrerol enhanced Nrf2-mediated cytoprotection of oxidative damage caused by H2O2, which may be inseparable from the activation of Akt and MAPK.

The role of Nrf2 in acute kidney injury: Novel molecular mechanisms and therapeutic approaches.

Acute kidney injury (AKI) is a common clinical syndrome that is related to high morbidity and mortality. Oxidative stress, including the production of reactive oxygen species (ROS), appears to be the main element in the occurrence of AKI and the cause of the progression of chronic kidney disease (CKD) into end-stage renal disease (ESRD). Nuclear factor erythroid 2 related factor 2 (Nrf2) is a significant regulator of redox balance that has been shown to improve kidney disease by eliminating ROS. To date, researchers have found that the use of Nrf2-activated compounds can effectively reduce ROS, thereby preventing or retarding the progression of various types of AKI. In this review, we summarized the molecular mechanisms of Nrf2 and ROS in AKI and described the latest findings on the therapeutic potential of Nrf2 activators in various types of AKI.

The hepatoprotective effect of myricetin against lipopolysaccharide and D-galactosamine-induced fulminant hepatitis.

Fulminant hepatitis (FH) is a severe liver disease characterized by extensive hepatic necrosis, oxidative stress, and inflammation. Myricetin (Myr), a botanical flavonoid glycoside, is recognized to exert antiapoptosis, anti-inflammatory, and antioxidant properties. In the current study, we focused on exploring the protective effects and underlying mechanisms of Myr against lipopolysaccharide (LPS) and D-galactosamine (D-GalN)-induced FH. These data indicated that Myr effectively protected from LPS/D-GalN-induced FH by lowering the mortality of mice, decreasing ALT and AST levels, and alleviating histopathological changes, oxidative stress, inflammation, and hepatic apoptosis. Moreover, Myr could efficiently mediate multiple signaling pathways, displaying not only the regulation of caspase-3/9 and P53 protein, inhibition of toll-like receptor 4 (TLR4)-nuclear factor-kappa B (NF-κB) activation, and -mitogen-activated protein kinase (MAPK), but also the increase of heme oxygenase-1 (HO-1) and nuclear factor-erythroid 2-related factor 2 (Nrf2) expression, as well as induction of AMP-activated protein kinase (AMPK) and acetyl-CoA carboxylase (ACC) phosphorylation in mice with LPS/D-GalN-induced FH. Importantly, our further results in vitro suggested that Myr remarkably attenuated H2O2-triggered hepatotoxicity and ROS generation, activated Keap1-Nrf2/HO-1 and AMPK/ACC signaling pathway. However, Myr-enhanced the expression of HO-1 and Nrf2 protein was reversed by Keap1-overexpression, Nrf2-null and AMPK inhibitor. Meanwhile, Myr-relieved hepatotoxicity excited by H2O2 was blocked by Nrf2-null and AMPK inhibitor. Taken together, Myr exhibits a protective role against LPS/D-GalN-induced FH by suppressing hepatic apoptosis, inflammation, and oxidative stress, likely involving in the regulation of apoptosis-related protein, TLR4-NF-κB/-MAPK and NLRP3 inflammasome, and AMPK-Nrf2/HO-1 signaling pathway.

Pterostilbene Protects Against Lipopolysaccharide/D-Galactosamine-Induced Acute Liver Failure by Upregulating the Nrf2 Pathway and Inhibiting NF-κB, MAPK, and NLRP3 Inflammasome Activation.

The purpose of this study was to evaluate the protective effect of pterostilbene (Psb) against lipopolysaccharide and D-galactosamine (L/D)-induced acute liver failure (ALF) in mice and its potential mechanisms. Histology of liver was detected by H&E staining. Aspartate aminotransferase (AST) and alanine aminotransferase (ALT) levels in serum and malondialdehyde (MDA), myeloperoxidase (MPO), glutathione (GSH), and superoxide dismutase (SOD) contents in liver were examined using detection kits. The levels of interleukin-6 (IL-6), tumor necrosis factor-α (TNF-α), and interleukin-1ß (IL-1ß) secretion were detected by ELISA. Meanwhile, MAPK, NF-κB, NLRP3 inflammasome, and Nrf2 were assessed by western blotting. Our findings showed that pretreatment with Psb protected against L/D-induced ALF by lowering the lethality, improving liver histology, reducing ALT, AST, IL-6, IL-1ß, TNF-α, MDA, and MPO levels, and boosting liver GSH content and SOD activity. Moreover, Psb pretreatment effectively suppressed inflammation by decreasing NLRP3 inflammasome, MAPK, and NF-κB pathway activations. Moreover, Psb pretreatment efficiently enhanced the expression of several antioxidant enzymes, mainly depending on Nrf2 activation. This was the first study to demonstrate that Psb protects against L/D-induced ALF by inactivating MAPK, NF-κb, and NLRP3 inflammasome and upregulating the Nrf2 signaling pathway, indicating a potential therapeutic application for ALF treatment.

Enhanced Keap1-Nrf2/Trx-1 axis by daphnetin protects against oxidative stress-driven hepatotoxicity via inhibiting ASK1/JNK and Txnip/NLRP3 inflammasome activation.

BACKGROUND: Oxidative stress-triggered fatal hepatotoxicity is an essential pathogenic factor in acute liver failure (ALF). AIMS: To investigate the protective effect of daphnetin (Daph) on tert-butyl hydroperoxide (t-BHP) and acetaminophen (APAP)-induced hepatotoxicity through altering Nrf2/Trx-1 pathway activation. MATERIALS AND METHODS: In vivo, male C57BL/6 mice with Wild-type (WT) and Nrf2-/- were divided into five groups and acute liver injury model were established by APAP or LPS/GalN after injection with Daph (20, 40, or 80 mg/kg), seperately. Then, liver tissue and serum were collected for biochemical determination, TUNEL and H & E staining, and western blot analysis. In vitro, HepG2 cells were used to investigate the protective effect and mechanism of daphnetin against ROS and apoptosis induced by t-BHP via apoptosis detection, western blot, immunofluorescence analysis, and sgRNA transfection. RESULTS: Our results indicated that Daph efficiently inhibited t-BHP-stimulated hepatotoxicity, and modulated Trx-1 expression and Nrf2 activation which decreased Keap1-overexpression in HepG2 cells. Moreover, Daph inhibited t-BHP-excited hepatotoxicity and enhanced Trx-1 expression, which was reversed in Nrf2-/- HepG2 cells. In vivo, a survival rate analysis first suggested that Daph significantly reduced the lethality induced by APAP or GalN/LPS in a Nrf2-dependent or -independent manner by using Nrf2-/- mice, respectively. Next, further results implicated that Daph not only effectively alleviated APAP-induced an increase of ALT and AST levels, histopathological changes, ROS overproduction, malondialdehyde (MDA) formation and GSH/GSSG reduction, but it also relieved hepatic apoptosis by strengthening the suppression of cleaved-caspase-3 and expression of P53 protein. Additionally, Daph attenuated mitochondrial dysfunction by suppressing ASK1/JNK activation and decreasing apoptosis-inducing factor (AIF) and Cytochrome c release and Bax mitochondrial translocation. Daph inhibited inflammatory responses by inactivating the thioredoxin-interacting protein (Txnip)/NLRP3 inflammasome. Furthermore, Daph efficiently enhanced Nrf2 nuclear translocation and Trx-1 expression. However, these effects in WT mice were eliminated in Nrf2-/- mice. CONCLUSIONS: These investigations demonstrated that Daph treatment has protective potential against oxidative stress-driven hepatotoxicity by inhibition of ASK1/JNK and Txnip/NLRP3 activation, which may be strongly related to the Nrf2/Trx-1 upregulation.

Chicoric acid alleviates lipopolysaccharide-induced acute lung injury in mice through anti-inflammatory and anti-oxidant activities.

Acute lung injury (ALI) is a severe clinical disease with high mortality rates. Chicoric acid (CA), an active component extracted from traditional Chinese medicine, was suggested to have anti-inflammatory and anti-oxidant activities. Inflammation and oxidative damage are implicated in the pathogenesis of ALI. In this study, we explored the protection effect of CA on LPS-induced ALI, and further discussed the possible molecular mechanisms. The results showed that CA could significantly improve the histological changes of LPS-induced acute lung injury. In addition, CA not only decreased LPS-stimulated protein leakage and lung wet/dry ratio but also reduced inflammatory cell infiltration, myeloperoxidase (MPO) activity and the generation of pro-inflammatory cytokines in bronchoalveolar lavage fluid (BALF). Meanwhile, CA lessened the reactive oxygen species (ROS) generation, and malondialdehyde (MDA) formation, and decreased glutathione (GSH) and superoxide dismutase (SOD) depletion, which were caused by LPS challenge. Furthermore, CA dramatically inhibited LPS-stimulated MAPK and NLRP3 activation and increased the expression of NAD (P) H: quinone oxidoreductase (NQO1), and dismutase (SOD), glutamate-cysteine ligase catalytic/modifier (GCLC/GCLM) subunit and heme oxygenase-1 (HO-1), as well as its upstream genes nuclear factor-erythroid 2-related factor 2 (Nrf2), which might be central to the protective effects of CA. In conclusion, these data indicated that the protective effects and mechanisms of CA on LPS-induced ALI and provided new insights for its application.

Pterostilbene Activates the Nrf2-Dependent Antioxidant Response to Ameliorate Arsenic-Induced Intracellular Damage and Apoptosis in Human Keratinocytes.

The NF-E2 p45-related factor 2 (Nrf2), a transcription factor that regulates the cellular adaptive response to oxidative stress, is a target for limiting tissue damage from exposure to environmental toxins, including arsenic. In the current study, we determine whether Pterostilbene (Pts), as a potent activator of Nrf2, has a protective effect on arsenic-induced cytotoxicity and apoptosis in human keratinocytes. Human keratinocytes (HaCaT) or mouse epidermal cells (JB6) were pretreated with Pts for 24 h prior to arsenic treatment. Harvested cells were analyzed by MTT, DCFH-DA, commercial kits, Flow cytometry assay and western blot analysis. Our results demonstrated that Pts effectively regulated the viability in HaCaT and JB6 cells, decreased the reactive oxygen species (ROS) generation and lipid peroxidation (MDA), and improved the NaAsO2-induced depletion of superoxide dismutase (SOD). Moreover, Pts treatment further dramatically inhibited NaAsO2-induced apoptosis, specifically the mitochondrial mediation of apoptosis, which coincided with the effective recovery of NaAsO2-induced mitochondrial membrane potential (ΔΨm) depolarization and cytochrome c release from the mitochondria. Furthermore, arsenic-induced decrease of anti-apoptotic factor Bcl-2 and Bcl-xl, and increase of pro-apoptotic factor Bax and Bad, as well as survival signal related factor caspase 3 activation were reversed by Pts treatment. Further mechanistic studies confirmed that Pts increased antioxidant enzyme expression in a dose-dependent manner, which was related to Nrf2 nuclear translocation. In addition, the effects of Pts on NaAsO2-induced cell viability were largely weakened when Nrf2 was knocked down. Together, our results provide evidence for the use of Pts to activate the Nrf2 pathway to alleviate arsenic-induced dermal damage.

Ceftiofur regulates LPS-induced production of cytokines and improves LPS-induced survival rate in mice.

The influence of ceftiofur on immune responses has been suggested by results of in vitro studies. This effect was studied using a murine model that measured mortality and early cytokine responses after challenge with endotoxin. To investigate the treatment of endotoxic mice with ceftiofur, mice were pretreated with ceftiofur at different times before and after challenge with a lethal dose of 30 mg/kg lipopolysaccharide (LPS). We found that 20 mg/kg ceftiofur had a significant protective effect and reduced the mortality of mice at early stages. To further understand the mechanism of action of ceftiofur, we examined plasma cytokine levels. Mice treated with LPS alone showed markedly increased plasma levels of TNF-alpha, IL-1beta, IL-6 and IL-10, whereas mice pretreated with 20 mg/kg ceftiofur showed significantly decreased plasma levels of TNF-alpha, IL-1beta and IL-6, but increased plasma levels of IL-10. These results support the idea that ceftiofur has a beneficial effect on LPS-induced endotoxemia caused by LPS through its modulation of cytokine levels. This confirms the effect of ceftiofur for the treatment of endotoxemia, which is caused by a Gram-negative bacterial infection.

Betulin exhibits anti-inflammatory activity in LPS-stimulated macrophages and endotoxin-shocked mice through an AMPK/AKT/Nrf2-dependent mechanism.

Continued oxidative stress can lead to chronic inflammation, which in turn could mediate most chronic diseases including cancer. Nuclear factor erythroid 2-related factor (Nrf2), a critical transcriptional activator for antioxidative responses, has envolved to be an attractive drug target for the treatment or prevention of human diseases. In the present study, we investigated the effects and mechanisms of betulin on Nrf2 activation and its involvement in the lipopolysaccharide (LPS)-triggered inflammatory system. In macrophages, betulin activated the Nrf2 signaling pathway and increased Nrf2-targeted antioxidant and detoxifying enzymes, including NADPH, quinine oxidoreductase 1 (NQO1), heme oxygenase-1 (HO-1), γ-glutamyl cysteine synthetase catalytic subunit (GCLC) and modifier subunit (GCLM) in a dose and time dependent manner. Importantly, we found betulin-induced activation of Nrf2 is AMPK/AKT/GSK3ß dependent, as pharmacologically inactivating AMPK blocked the activating effect of betulin on AKT, GSK3ß and Nrf2. Furthermore, betulin attenuated LPS-induced inflammatory mediators (iNOS and COX-2) and MAPK inflammatory signaling pathway. The effect of betulin on HO-1 and NQO1 upregulation, iNOS and COX-2 the downregulation, and survival time extension was largely weakened when Nrf2 was depleted in vitro and in vivo. Our results demonstrate that the AMPK/AKT/Nrf2 pathways are essential for the anti-inflammatory effects of betulin in LPS-stimulated macrophages and endotoxin-shocked mice.

Asiatic acid enhances Nrf2 signaling to protect HepG2 cells from oxidative damage through Akt and ERK activation.

Asiatic acid (AA), a natural triterpene isolated from the plant Centella asiatica, have antioxidative potential, but the molecular mechanism of AA against oxidative stress remains unclear. Our study was performed to investigate the antioxidative effect of AA against oxidative stress and the antioxidative mechanism in tert-butyl hydroperoxide (t-BHP) -stimulated the HepG2 cells. The results showed that AA suppressed t-BHP-induced cytotoxicity, apoptosis, and reactive oxygen species (ROS) generation. Additionally, AA activated the nuclear factor erythroid 2-related factor 2 (Nrf2) signal, which was closely related to induction Nrf2 nuclear translocation, reduction the expression of Keap1 and up-regulation the activity of the antioxidant response element (ARE). Meanwhile, activation of Nrf2 signal upregulated the protein expressions of antioxidant genes, including heme oxygenase-1 (HO-1), NAD(P)H: quinone oxidase (NQO-1), and glutamyl cysteine ligase catalytic subunit (GCLC). Excitingly, Knockout of Nrf2 almost abolished AA-mediated antioxidant activity and cytoprotection against t-BHP. Further studies showed the mechanism underlying that AA induced Nrf2 activation in HepG2 cells via Akt and ERK signal activation. We found Akt and ERK inhibitors treatment attenuated AA-mediated Nrf2 nuclear translocation. Furthermore, treatment with either Akt or ERK inhibitor also decreased AA-mediated cytoprotection against t-BHP-induced cellular damage. Collectively, these results presented in this study indicate that AA has the protective effect against t-BHP-induced cellular damage and oxidative stress by modulating Nrf2 signaling through activating the signals of Akt and ERK.