Acetaminophen and lipopolysaccharide act in synergy for the production of pro-inflammatory cytokines in murine RAW264.7 macrophages

Selenium Ameliorates Acetaminophen-Induced Oxidative Stress via MAPK and Nrf2 Pathways in Mice

Overdose of acetaminophen (paracetamol), a widely used non-prescriptive analgesic and antipyretic medication, is one of the main causes of drug-induced acute liver failure around the world. Oxidative stress contributes to this hepatotoxicity. Antioxidants are known to protect the liver from oxidative stress. Selenium, a potent antioxidant, is a commonly used micronutrient. Here, we evaluated the protective effect of selenium on acetaminophen-induced hepatotoxicity. Treating Wistar albino mice with sodium selenite (1 mg/kg) before or after inducing hepatotoxicity with acetaminophen (150 mg/kg) significantly reduced the levels of liver injury biomarkers such as serum glutamate oxaloacetate transaminase and serum glutamate pyruvate transaminase. In addition, selenium-treated mice showed decreased levels of oxidative stress markers such as protein carbonyls and myeloperoxidase. Acetaminophen treatment stimulated all three mitogen-activated protein kinases (MAPKs) and Keap1 and decreased the expression of nuclear factor erythroid 2-related factor 2 (Nrf2) and heme oxygenase-1 in liver and in isolated mouse peritoneal macrophages, which was reversed by selenium treatment. Our findings suggest that the reactive oxygen species-mediated Nrf2 and MAPK pathways are critical players in acetaminophen-induced hepatotoxicity. These key findings offer an alternative therapeutic target for addressing acetaminophen-induced hepatotoxicity.

Macrophages and glial cells: Innate immune drivers of inflammatory arthritic pain perception from peripheral joints to the central nervous system

Millions of people suffer from arthritis worldwide, consistently struggling with daily activities due to debilitating pain evoked by this disease. Perhaps the most intensively investigated type of inflammatory arthritis is rheumatoid arthritis (RA), where, despite considerable advances in research and clinical management, gaps regarding the neuroimmune interactions that guide inflammation and chronic pain in this disease remain to be clarified. The pain and inflammation associated with arthritis are not isolated to the joints, and inflammatory mechanisms induced by different immune and glial cells in other tissues may affect the development of chronic pain that results from the disease. This review aims to provide an overview of the state-of-the-art research on the roles that innate immune, and glial cells play in the onset and maintenance of arthritis-associated pain, reviewing nociceptive pathways from the joint through the dorsal root ganglion, spinal circuits, and different structures in the brain. We will focus on the cellular mechanisms related to neuroinflammation and pain, and treatments targeting these mechanisms from the periphery and the CNS. A comprehensive understanding of the role these cells play in peripheral inflammation and initiation of pain and the central pathways in the spinal cord and brain will facilitate identifying new targets and pathways to aide in developing therapeutic strategies to treat joint pain associated with RA.

Baltic amber teething necklaces: could succinic acid leaching from beads provide anti-inflammatory effects?

Background

Baltic amber teething necklaces have been popularized as a safe and natural alternative to conventional or pharmacological medicines for the management of teething pain. However, claims made by retailers regarding the efficacy and mechanism of action of these necklaces lack scientific or clinical basis. The claim most closely resembling science is the assertion that succinic acid will leach out of the beads and through the skin of the wearer and carry out anti-inflammatory and analgesic effects. The objective of the current research is to scientifically assess this claim.

Methods

Beads from necklaces were powdered for identification by infrared spectroscopy, and dissolved in sulfuric acid for quantification of succinic acid using HPLC. Succinic acid release from beads was assessed by long-term submersion of amber beads (separated according to light, medium and dark brown colour) in solvents relevant to human skin conditions. The potential for succinic acid to have anti-inflammatory effects was assessed by measuring the release of inflammatory cytokines IL-1α, IL-1β, IL-8 and TNFα, and the inflammatory messenger PGE2, from THP-1 human macrophages after treatment with succinic acid and LPS.

Results

Amber teething necklaces were positively identified as Baltic amber, by comparison of the beads’ infrared spectrum to the literature, and by their succinic acid content (1.5 mg per bead; 1.44% w/w). However, whole amber beads submerged in octanol or pH 5.5 phosphate buffered saline did not release any measurable succinic acid, except for the light-coloured beads in octanol which broke into tiny fragments. Additionally, treatment of macrophages with succinic acid did not reduce the release of any inflammatory cytokines measured, and displayed toxicity to the cells at high concentrations.

Conclusions

While amber teething necklaces are genuine Baltic amber, we have found no evidence to suggest that the purported active ingredient succinic acid could be released from the beads into human skin. Additionally, we found no evidence to suggest that succinic acid has anti-inflammatory properties.

A Possible Anti-Inflammatory Effect of Proline in the Brain Cortex and Cerebellum of Rats

Although many studies show the toxic effects of proline, recently it has been reported some anti-inflammatory effect of this amino acid. Our principal objective was to investigate the effects of proline on the alterations caused by LPS (lipopolysaccharide) administration in the cerebral cortex and cerebellum of young Wistar rats. The animals were divided into four groups: control (0.85% saline); proline, (12.8 μmol of proline/g body weight from day 7 to 13; 14.6 μmol of proline/g body weight from day 14 to 17 and 16.4 μmol of proline/g body weight from day 18 to 21); LPS (1 mg/g body weight); LPS plus proline. The animals were killed at 22 days of age, 12 h after the last injection, by decapitation without anesthesia. The brain cortex and cerebellum were separated for chemical determinations. The effects of proline and LPS in the cerebral cortex and cerebellum on the expression of S100B and GFAP, oxidative stress parameters, enzymes of phosphoryl transfer network activity, and mitochondrial respiration chain complexes were investigated. Two-way ANOVA showed that the administration of proline did not alter the analyzed parameter in cerebral cortex and cerebellum. On the other hand, LPS administration caused a change in these parameters. Besides, the co-administration of proline and LPS showed the ability of Pro in preventing the effects of LPS. These results indicated that LPS induces inflammation, oxidative stress, and alters energy parameters in cerebral cortex and cerebellum of the rats. Moreover, co-administration of Pro was able to prevent these harmful effects of LPS.

Potentiation of LPS-Induced Apoptotic Cell Death in Human Hepatoma HepG2 Cells by Aspirin via ROS and Mitochondrial Dysfunction: Protection by N-Acetyl Cysteine

Cytotoxicity and inflammation-associated toxic responses have been observed to be induced by bacterial lipopolysaccharides (LPS) in vitro and in vivo respectively. Use of nonsteroidal anti-inflammatory drugs (NSAIDs), such as aspirin, has been reported to be beneficial in inflammation-associated diseases like cancer, diabetes and cardiovascular disorders. Their precise molecular mechanisms, however, are not clearly understood. Our previous studies on aspirin treated HepG2 cells strongly suggest cell cycle arrest and induction of apoptosis associated with mitochondrial dysfunction. In the present study, we have further demonstrated that HepG2 cells treated with LPS alone or in combination with aspirin induces subcellular toxic responses which are accompanied by increase in reactive oxygen species (ROS) production, oxidative stress, mitochondrial respiratory dysfunction and apoptosis. The LPS/Aspirin induced toxicity was attenuated by pre-treatment of cells with N-acetyl cysteine (NAC). Alterations in oxidative stress and glutathione-dependent redox-homeostasis were more pronounced in mitochondria compared to extra- mitochondrial cellular compartments. Pre-treatment of HepG2 cells with NAC exhibited a selective protection in redox homeostasis and mitochondrial dysfunction. Our results suggest that the altered redox metabolism, oxidative stress and mitochondrial function in HepG2 cells play a critical role in LPS/aspirin-induced cytotoxicity. These results may help in better understanding the pharmacological, toxicological and therapeutic properties of NSAIDs in cancer cells exposed to bacterial endotoxins.

NAC attenuates LPS-induced toxicity in aspirin-sensitized mouse macrophages via suppression of oxidative stress and mitochondrial dysfunction

Bacterial endotoxin lipopolysaccharide (LPS) induces the production of inflammatory cytokines and reactive oxygen species (ROS) under in vivo and in vitro conditions. Acetylsalicylic acid (ASA, aspirin) is a commonly used anti-inflammatory drug. Our aim was to study the effects of N-acetyl cysteine (NAC), an antioxidant precursor of GSH synthesis, on aspirin-sensitized macrophages treated with LPS. We investigated the effects of LPS alone and in conjunction with a sub-toxic concentration of ASA, on metabolic and oxidative stress, apoptosis, and mitochondrial function using J774.2 mouse macrophage cell line. Protection from LPS-induced toxicity by NAC was also studied. LPS alone markedly induced ROS production and oxidative stress in macrophage cells. When ASA was added to LPS-treated macrophages, the increase in oxidative stress was significantly higher than that with LPS alone. Similarly, alteration in glutathione-dependent redox metabolism was also observed in macrophages after treatment with LPS and ASA. The combination of LPS and ASA selectively altered the CYP 3A4, CYP 2E1 and CYP 1A1 catalytic activities. Mitochondrial respiratory complexes and ATP production were also inhibited by LPS-ASA treatment. Furthermore a higher apoptotic cell death was also observed in LPS-ASA treated macrophages. NAC pre-treatment showed protection against oxidative stress induced apoptosis and mitochondrial dysfunction. These effects are presumed, at least in part, to be associated with alterations in NF-κB/Nrf-2 mediated cell signaling. These results suggest that macrophages are more sensitive to LPS when challenged with ASA and that NAC pre-treatment protects the macrophages from these deleterious effects.

Rose Bengal suppresses gastric cancer cell proliferation via apoptosis and inhibits nitric oxide formation in macrophages

Rose Bengal (RB) has been used as a safe agent in clinical diagnosis. In addition, it is used as a photodynamic sensitizer for removing microorganisms and cancer cells. Recently, its preferential toxicity after direct exposure to cancer cells was proven. The present study focuses on anti-cancer and anti-inflammatory activities of RB. The toxicity of RB against AGS gastric cancer and NIH 3T3 fibroblast cell lines was studied using an MTT assay. Patterns of any cell death among the AGS cells were defined using Annexin-V and PI staining. In addition, the effect of RB on nitric oxide (NO) and prostaglandin E(2) (PGE(2)) production induced by lipopolysaccha-ride in J774A.1 macrophages was determined. Modulation of inducible nitric oxide synthase (iNOS) and cyclooxygenase (COX)-2 expressions in the macrophages was also evaluated by Western blots. The results showed that AGS cells exhibited significant concentration-dependent decreases in growth in response to RB; these cells showed a greater growth inhibition than did non-malignant 3T3 cells, suggesting that anti-growth activity of RB could be cell-specific. Moreover, AGS cells exposed to RB exhibited a significant increase in apoptosis; only at high RB doses did the cells display significant levels of necrosis. While RB also caused a modest decrease in the growth of J774A.1 macrophages, the cells displayed remarkable decreases in NO production and iNOS expression without significant concurrent modulation in PGE(2) production or COX-2 expression. The data from this study appears to suggest that RB differentially impacts on transformed cell lines, preferentially suppresses growth of a gastric cancer cell line through induction of apoptosis, and induces changes in cells that could reflect potential anti-inflammatory effects that might be induced in situ.

Acetaminophen attenuates doxorubicin-induced cardiac fibrosis via osteopontin and GATA4 regulation: reduction of oxidant levels

It is well documented in animal and human studies that therapy with the anti-cancer drug doxorubicin (DOX) induces fibrosis, cardiac dysfunction, and cell death. The most widely accepted mechanism of cardiac injury is through production of reactive oxygen species (ROS), which cause mitochondrial damage, sarcomere structural alterations, and altered gene expression in myocytes and fibroblasts. Here we investigated the effects of acetaminophen (APAP, N-acetyl-para-aminophenol) on DOX-induced cardiac injury and fibrosis in the presence or absence of osteopontin (OPN). H9c2 rat heart-derived embryonic myoblasts were exposed to increasing concentrations of DOX ± APAP; cell viability, oxidative stress, and OPN transcript levels were analyzed. We found a dose-dependent decrease in cell viability and a corresponding increase in intracellular oxidants at the tested concentrations of DOX. These effects were attenuated in the presence of APAP. RT-PCR analysis revealed a small increase in OPN transcript levels in response to DOX, which was suppressed by APAP. When male 10-12-week-old mice (OPN(+/+) or OPN(-/-)) were given weekly injections of DOX ± APAP for 4 weeks there was substantial cardiac fibrosis in OPN(+/+) and, to a lesser extent, in OPN(-/-) mice. In both groups, APAP decreased fibrosis to near baseline levels. Activity of the pro-survival GATA4 transcription factor was diminished by DOX in both mouse genotypes, but retained baseline activity in the presence of APAP. These effects were mediated, in part, by the ability of APAP, acting as an anti-inflammatory agent, to decrease intracellular ROS levels, consequently diminishing the injury-induced increase in OPN levels.

A fraction of stem bark extract of Entada africana suppresses lipopolysaccharide-induced inflammation in RAW 264.7 cells

ETHNOPHARMACOLOGICAL RELEVANCE

Entada africana is a plant used in African traditional medicine for the treatment of stomachache, fever, liver related diseases, wound healing, cataract and dysentery.

AIMS OF THE STUDY

This study aimed at evaluating the anti-inflammatory activity of fractions of the stem bark extract of the plant using lipopolysaccharide (LPS)-induced inflammation in RAW 264.7 macrophages model.

MATERIALS AND METHODS

The crude extract was prepared using the mixture CH2Cl2/MeOH (1:1, v/v) and fractionated by flash chromatography using solvents of increasing polarity to obtain five different fractions. The effects of the fractions on the cells viability were studied by the 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) assay and their inhibitory activity against LPS-induced nitric oxide (NO) production screened by Griess test. The most active fraction was further investigated for its effects on reactive oxygen species (ROS) production using flux cytometry, the expression of inducible nitric oxide synthase (iNOS), pro-and anti-inflammatory cytokines (IL1β, TNFα, IL6, IL10 and IL13) by RT-PCR, and the activity of the enzyme p38 MAPK kinase by enzyme-linked immunosorbent assay (ELISA).

RESULTS

The fractions presented no significant effect on the viability of macrophages at 100 μg/ml after 24h incubation. The CH2Cl2/MeOH 5% (Ea5) fraction was found to be the most potent in inhibiting NO production with a half inhibition concentration (IC50)=18.36 μg/ml, and showed the highest inhibition percentage (89.068%) in comparison with Baicalin (63.34%), an external standard at 50 μg/ml. Ea5, as well as Baicalin significantly (P<0.05) inhibited the expression of TNFα, IL6 and IL1β mRNA, attenuated mRNA expression of inducible NO synthase in a concentration-dependent manner, stimulated the expression of anti-inflammatory cytokines (IL10 and IL13), and showed a 30% inhibition of the activity of p38 MAPK kinase.

CONCLUSION

The results of the present study indicate that the fraction Ea5 of Entada africana possesses most potent in vitro anti-inflammatory activity and may contain compounds useful as a therapeutic agent in the treatment of inflammatory related diseases cause by over-activation of macrophages.

Inflammasomes in liver diseases

Inflammation is a common element in the pathogenesis of most chronic liver diseases that lead to fibrosis and cirrhosis. Inflammation is characterized by activation of innate immune cells and production of pro-inflammatory cytokines IL-1α, IL-1β, and TNFα. Inflammasomes are intracellular multiprotein complexes expressed in both parenchymal and non-parenchymal cells of the liver that in response to cellular danger signals activate caspase-1, and release IL-1β and IL-18. The importance of inflammasome activation in various forms of liver diseases in relation to liver damage, steatosis, inflammation and fibrosis is discussed in this review.

Gentiana manshurica Kitagawa prevents acetaminophen-induced acute hepatic injury in mice via inhibiting JNK/ERK MAPK pathway

AIM: To investigate the in vivo hepatoprotective effects and mechanisms of Gentiana manshurica Kitagawa (GM) in acetaminophen (APAP)-induced liver injury in mice.

METHODS: GM (200, 150 or 50 mg/kg body weight) or N-acetyl-L-cysteine (NAC; 300 mg/kg body weight) was administrated orally with a single dose 2 h prior to APAP (300 mg/kg body weight) injection in mice.

RESULTS: APAP treatment significantly depleted hepatic glutathione (GSH), increased serum aspartate aminotransferase (AST), alanine aminotransferase (ALT) and malonyldialdehyde (MDA) and 4-hydroxynonenal levels, and decreased hepatic activity of glutathione peroxidase (GSH-px) and superoxide dismutase (SOD). However, the pretreatment of GM significantly alleviated APAP-induced oxidative stress by increasing GSH content, decreasing serum ALT, AST and MDA, and retaining the activity of GSH-px and SOD in the liver. Furthermore, GM pretreatment can inhibit caspase-3 activation and phosphorylation of c-Jun-NH2-terminal protein kinase 2 (JNK1/2) and extracellular signal-regulated kinase (ERK). GM also remarkably attenuated hepatocyte apoptosis confirmed by the terminal deoxynucleotidyl transferase mediated dUTP nick end-labeling method.

CONCLUSION: Hepatoprotective effects of GM against APAP-induced acute toxicity are mediated either by preventing the decline of hepatic antioxidant status or its direct anti-apoptosis capacity. These results support that GM is a potent hepatoprotective agent.