LPS inhibits caspase 3-dependent apoptosis in RAW264.7 macrophages induced by the AMPK activator AICAR

Role of metformin in inflammation

BACKGROUND

Metformin has good anti-hyperglycemic effectiveness, but does not induce hypoglycemia，is very safe, and has become the preferred drug for the treatment of type 2 diabetes. Recently, the other effects of metformin, such as being anti-inflammatory and delaying aging, have also attracted increased attention.

METHODS AND RESULTS

The relevant literatures on pubmed and other websites for reading, classification and sorting, and did not involve any animal experiments.

CONCLUSION

Metformin has anti-inflammatory effects through multiple routes, which provides potential therapeutic targets for certain inflammatory diseases, such as neuroinflammation and rheumatoid arthritis. In addition, inflammation is a key component of tumor occurrence and development ; thus, targeted inflammatory intervention is a significant benefit for both cancer prevention and treatment. Therefore, metformin may have further potential for inflammation-related disease prevention and treatmen. However, the inflammatory mechanism is complex; various molecules are connected and influence each other. For example, metformin significantly inhibits p65 nuclear translocation, but pretreatment with compound C, an AMPK inhibitor, abolishes this effect, and silencing of HMGB1 inhibits NF-κB activation . SIRT1 deacetylates FoxO, increasing its transcriptional activity . mTOR in dendritic cells regulates FoxO1 via AKT. The interactions among various molecules should be further explored to clarify their specific mechanisms and provide more direction for the treatment of inflammatory diseases, as well as cancer.

Urocortin participates in LPS-induced apoptosis of THP-1 macrophages via S1P-cPLA2 signaling pathway

There is little literature showing the effect of urocortin (UCN) on macrophage apoptosis. The underlying mechanism is also unclear. This work was to investigate the involvement of UCN in the regulation of LPS-induced macrophage apoptosis and hence in the prevention from the atherosclerotic lesion development through targeting PLA2. Flow cytometry analysis showed that cell apoptosis was increased by more than 50% after LPS treatment in human THP-1 macrophage. Lp-PLA2 and cPLA2 were found to mediate LPS-induced macrophage apoptosis and NF-κB differentially influenced the expression of Lp-PLA2 and cPLA2. However, the reverse regulation of the expression of Lp-PLA2 and cPLA2 by NF-κB suggested that NF-κB may not be a key target for regulating macrophage apoptosis. Interestingly, we found that the approximate three folds upregulation of cPLA2 was in line with the induction of S1P formation and cell apoptosis by LPS. Inversely, LPS obviously decreased UCN expression by about 50% and secretion by about 25%. Both the enzyme inhibitor and knockdown expression of cPLA2 could completely abolish LPS-induced cell apoptosis. In addition, suppression of S1P synthesis by Sphk1 inhibitor PF-543 reduced the expression of cPLA2 and cell apoptosis but at the same time restored the normal level of UCN in cell culture supernatant. Furthermore, addition of exogenous UCN also reversed LPS-induced expression of cPLA2 and apoptosis. Taken together, UCN may be the reverse regulator of LPS-S1P-cPLA2-apoptosis pathway, thereby contributing to the prevention from the formation of unstable plaques.

Inorganic nitrite increases the susceptibility of tilapia (Oreochromis niloticus) leucocytes to Streptococcus agalactiae

Deteriorating water quality, especially from high concentrations of nitrite, is currently largely blamed for disease outbreaks in farmed tilapia (Oreochromis niloticus). In this study, the underlying mechanism of nitrite on the susceptibility of tilapia leucocytes to Streptococcus agalactiae (S. agalactiae) was studied. We found that a high dose of heat-killed S. agalactiae decreased tilapia leucocytes cell viability, whereas nitrite decreased the cell viability of leucocytes exposed to a low dose of bacteria. Bacterial challenge increased the production of nitric oxide (NO), whereas nitrite and bacteria coexposure caused higher NO production than nitrite or bacterial exposure alone. Cell viability increased after elimination of NO, and negative correlations existed between cell viability and the NO content, suggesting that nitrite increased the susceptibility of the leucocytes against S. agalactiae was NO-dependent. For a more comprehensive understanding of the mechanism of nitrite affecting disease resistance in tilapia leucocytes, an RNA-Seq-based transcriptome was generated. The results showed that 6173 transcripts were differently expressed, and the differentially expressed transcripts (DETs) of the bacterial group, nitrite group and bacteria-nitrite co-treatment group compared to the control group were selected for GO and KEGG analyses. The DETs in the bacterial group and bacteria-nitrite cotreatment group were highly involved with the membrane component, signal transduction, and immune responses. KEGG analysis showed that the protein processing in the endoplasmic reticulum and the AMPK signaling pathway, which are related to autophagy, were significantly enriched in the cotreatment group but not in bacterial group. In addition, the mRNA expression of ten DETs and several autophagy and apoptosis related genes validated by q-PCR showed the high reliability of the RNA-seq. Taken together, the results of this study suggest that nitrite may increase the susceptibility of tilapia leucocytes to S. agalactiae by generating excess NO to affect the autophagy and apoptosis process.

Anesthetic effects of isoflurane and the molecular mechanism underlying isoflurane‑inhibited aggressiveness of hepatic carcinoma

Anesthesia is produced by drugs or other methods, and refers to the attenuation of pain via reversible suppression of neuronal transmission in the central and peripheral nervous systems, during surgery. Clinical investigations have indicated that the anesthetic action of isoflurane is efficient to alleviate pain during tumor resection clinical trials. In addition, it has been reported that isoflurane can induce caspase-3 activation and is associated with apoptosis of tumor cells. The present study investigated the anesthetic effects and molecular mechanisms underlying isoflurane-induced apoptosis in patients with hepatic carcinoma. Furthermore, the pain of patients with hepatic carcinoma was evaluated during the perioperative period according to the pain index. The apoptotic rate of hepatic carcinoma cells was analyzed in tumor tissues using TUNEL assay. The expression levels of apoptosis-associated proteins were detected in liver cancer cells following anesthesia in patients. Phosphoinositide 3-kinase/protein kinase B (PI3K/AKT) and nuclear factor (NF)-κB signaling pathways were also analyzed in liver cancer cells following treatment with isoflurane. The results demonstrated that isoflurane inhibited growth and decreased viability of liver cancer cells in vitro and in vivo. In addition, the apoptotic rate was increased in cells obtained from isoflurane-treated patients. The results also demonstrated that isoflurane upregulated the expression levels of proapoptotic genes and downregulated anti-apoptotic mRNA expression. In addition, a molecular mechanism analysis indicated that isoflurane inhibited PI3K and AKT expression in liver cancer cells. Isoflurane also induced caspase-3 activation in liver cancer cells. Furthermore, isoflurane treatment attenuated NF-κB activity and inhibited migration and invasion of liver cancer cells. In conclusion, these findings indicated that isoflurane treatment efficiently attenuated surgical pain and inhibited tumor aggressiveness via regulation of NF-κB activity and the PI3K/AKT signaling pathway, thus suggesting that isoflurane is an efficient anesthetic drug that induces pain remission and promotes apoptosis of liver cancer cells.

The in Vitro Inhibitory Effect of Ectromelia Virus Infection on Innate and Adaptive Immune Properties of GM-CSF-Derived Bone Marrow Cells Is Mouse Strain-Independent

Ectromelia virus (ECTV) belongs to the Orthopoxvirus genus of the Poxviridae family and is a natural pathogen of mice. Certain strains of mice are highly susceptible to ECTV infection and develop mousepox, a lethal disease similar to smallpox of humans caused by variola virus. Currently, the mousepox model is one of the available small animal models for investigating pathogenesis of generalized viral infections. Resistance and susceptibility to ECTV infection in mice are controlled by many genetic factors and are associated with multiple mechanisms of immune response, including preferential polarization of T helper (Th) immune response toward Th1 (protective) or Th2 (non-protective) profile. We hypothesized that viral-induced inhibitory effects on immune properties of conventional dendritic cells (cDCs) are more pronounced in ECTV-susceptible than in resistant mouse strains. To this extent, we confronted the cDCs from resistant (C57BL/6) and susceptible (BALB/c) mice with ECTV, regarding their reactivity and potential to drive T cell responses following infection. Our results showed that in vitro infection of granulocyte-macrophage colony-stimulating factor-derived bone marrow cells (GM-BM—comprised of cDCs and macrophages) from C57BL/6 and BALB/c mice similarly down-regulated multiple genes engaged in DC innate and adaptive immune functions, including antigen uptake, processing and presentation, chemokines and cytokines synthesis, and signal transduction. On the contrary, ECTV infection up-regulated Il10 in GM-BM derived from both strains of mice. Moreover, ECTV similarly inhibited surface expression of major histocompatibility complex and costimulatory molecules on GM-BM, explaining the inability of the cells to attain full maturation after Toll-like receptor (TLR)4 agonist treatment. Additionally, cells from both strains of mice failed to produce cytokines and chemokines engaged in T cell priming and Th1/Th2 polarization after TLR4 stimulation. These data strongly suggest that in vitro modulation of GM-BM innate and adaptive immune functions by ECTV occurs irrespective of whether the mouse strain is susceptible or resistant to infection. Moreover, ECTV limits the GM-BM (including cDCs) capacity to stimulate protective Th1 immune response. We cannot exclude that this may be an important factor in the generation of non-protective Th2 immune response in susceptible BALB/c mice in vivo.

Aerobic Exercise Training Selectively Changes Oxysterol Levels and Metabolism Reducing Cholesterol Accumulation in the Aorta of Dyslipidemic Mice

Background: Oxysterols are bioactive lipids that control cellular cholesterol synthesis, uptake, and exportation besides mediating inflammation and cytotoxicity that modulate the development of atherosclerosis. Aerobic exercise training (AET) prevents and regresses atherosclerosis by the improvement of lipid metabolism, reverse cholesterol transport (RCT) and antioxidant defenses in the arterial wall. We investigated in dyslipidemic mice the role of a 6-week AET program in the content of plasma and aortic arch cholesterol and oxysterols, the expression of genes related to cholesterol flux and the effect of the exercise-mimetic AICAR, an AMPK activator, in macrophage oxysterols concentration. Methods: Sixteen-week old male apo E KO mice fed a chow diet were included in the protocol. Animals were trained in a treadmill running, 15 m/min, 5 days/week, for 60 min (T; n = 29). A control group was kept sedentary (S; n = 32). Plasma lipids and glucose were determined by enzymatic techniques and glucometer, respectively. Cholesterol and oxysterols in aortic arch and macrophages were measured by gas chromatography/mass spectrometry. The expression of genes involved in lipid metabolism was determined by RT-qPCR. The effect of AMPK in oxysterols metabolism was determined in J774 macrophages treated with 0.25 mM AICAR. Results: Body weight and plasma TC, TG, HDL-c, glucose, and oxysterols were similar between groups. As compared to S group, AET enhanced 7β-hydroxycholesterol (70%) and reduced cholesterol (32%) in aorta. In addition, exercise increased Cyp27a1 (54%), Cd36 (75%), Cat (70%), Prkaa1 (40%), and Prkaa2 (51%) mRNA. In macrophages, the activation of AMPK followed by incubation with HDL₂ increased Abca1 (52%) and Cd36 (220%) and decrease Prkaa1 (19%), Cyp27a1 (47%) and 7α-hydroxycholesterol level. Conclusion: AET increases 7β-hydroxycholesterol in the aortic arch of dyslipidemic mice, which is related to the enhanced expression of Cd36. In addition, the increase and reduction of Cyp27a1 and Cyp7b1 in trained mice may contribute to enhance levels of 27-OH C. Both oxysterols may act as an alternative pathway for the RCT contributing to the reduction of cholesterol in the aortic arch preventing atherogenesis.

Regulation of pulmonary endothelial barrier function by kinases

The pulmonary endothelium is the target of continuous physiological and pathological stimuli that affect its crucial barrier function. The regulation, defense, and repair of endothelial barrier function require complex biochemical processes. This review examines the role of endothelial phosphorylating enzymes, kinases, a class with profound, interdigitating influences on endothelial permeability and lung function.

Role of Inflammatory and Oxidative Stress, Cytochrome P450 2E1, and Bile Acid Disturbance in Rat Liver Injury Induced by Isoniazid and Lipopolysaccharide Cotreatment

Isoniazid (INH) remains the core drug in tuberculosis management, but serious hepatotoxicity and potentially fatal liver injury continue to accompany INH consumption. Among numerous theories that have been established to explain INH-induced liver injury, an inflammatory stress theory has recently been widely used to explain the idiosyncrasy. Inflammatory stress usually sensitizes tissues to a drug's toxic consequences. Therefore, the present study was conducted to verify whether bacterial lipopolysaccharide (LPS)-induced inflammation may have a role in enhancing INH hepatotoxicity. While single INH or LPS administration showed no major toxicity signs, INH-LPS cotreatment intensified liver toxicity. Both blood biomarkers and histological evaluations clearly showed positive signs of severe liver damage accompanied by massive necrosis, inflammatory infiltration, and hepatic steatosis. Furthermore, elevated serum levels of bile acid associated with the repression of bile acid synthesis and transport regulatory parameters were observed. Moreover, the principal impact of cytochrome P450 2E1 (CYP2E1) on INH toxicity could be anticipated, as its protein expression showed enormous increases in INH-LPS-cotreated animals. Furthermore, the crucial role of CYP2E1 in the production of reactive oxygen species (ROS) was clearly obvious in the repression of hepatic antioxidant parameters. In summary, these results confirmed that this LPS-induced inflammation model might prove valuable in revealing the hepatotoxic mechanisms of INH and the crucial role played by CYP2E1 in the initiation and propagation of INH-induced liver damage, information which could be very useful to clinicians in understanding the pathogenesis of drug-induced liver injury.

Novel regulators of endothelial barrier function

Endothelial barrier function is an essential and tightly regulated process that ensures proper compartmentalization of the vascular and interstitial space, while allowing for the diffusive exchange of small molecules and the controlled trafficking of macromolecules and immune cells. Failure to control endothelial barrier integrity results in excessive leakage of fluid and proteins from the vasculature that can rapidly become fatal in scenarios such as sepsis or the acute respiratory distress syndrome. Here, we highlight recent advances in our understanding on the regulation of endothelial permeability, with a specific focus on the endothelial glycocalyx and endothelial scaffolds, regulatory intracellular signaling cascades, as well as triggers and mediators that either disrupt or enhance endothelial barrier integrity, and provide our perspective as to areas of seeming controversy and knowledge gaps, respectively.