Ruthenium complex, TQ‑5, protects against LPS‑induced macrophage inflammation and acute liver injury in mice via downregulating NF‑κB pathways (original) (raw)

Mechanisms of TQ-6, a Novel Ruthenium-Derivative Compound, against Lipopolysaccharide-Induced In Vitro Macrophage Activation and Liver Injury in Experimental Mice: The Crucial Role of p38 MAPK and NF-κB Signaling

Cells

Several studies have reported that metal complexes exhibit anti-inflammatory activities; however, the molecular mechanism is not well understood. In this study, we used a potent ruthenium (II)-derived compound, [Ru(η6-cymene)2-(1H-benzoimidazol-2-yl)-quinoline Cl]BF4 (TQ-6), to investigate the molecular mechanisms underlying the anti-inflammatory effects against lipopolysaccharide (LPS)-induced macrophage activation and liver injury in mice. Treating LPS-stimulated RAW 264.7 cells with TQ-6 suppressed nitric oxide (NO) production and inducible nitric oxide synthase (iNOS) expression in a concentration-dependent manner. The LPS-induced expression of tumor necrosis factor alpha (TNF-α) and interleukin-1 beta (IL-1β) were reduced in TQ-6-treated cells. TQ-6 suppressed, LPS-stimulated p38 MAPK phosphorylation, IκBα degradation, and p65 nuclear translocation in cells. Consistent with the in vitro studies, TQ-6 also suppressed the expression of iNOS, TNF-α, and p65 in the mouse model with...

Ruthenium derivatives attenuate LPS-induced inflammatory responses and liver injury via suppressing NF-κB signaling and free radical production

Bioorganic Chemistry, 2020

Ruthenium metal complex has been shown to exert several chemical and biological activities. A series of three novel ruthenium derivatives (TQ 1, 2 and 4) were synthesized to evaluate the anti-inflammatory and hepatoprotective activities in lipopolysaccharide (LPS)-stimulated macrophages and mice liver injury. The hydroxyl radical (OH°) scavenging activity of these derivatives has also been evaluated. The results revealed that among the tested compounds, TQ-4 effectively attenuated LPS-induced abnormal alteration in liver histoarchistructure via reducing alanine transaminase (ALT) and aspartate transaminase (AST). This compound exhibited significant inhibition of inflammatory cytokines (TNF-α and IL-1β), inflammatory enzyme (iNOS), the component of NF-κB signaling pathway (p65) and JNK phosphorylation in LPS-induced mice liver tissues. In vitro results showed that TQ-4 had the best inhibition of NO production and iNOS expression in LPS-induced RAW 264.7 cells. Mechanistic approach indicated that TQ-4 inhibited the LPS-induced JNK phosphorylation, IκBα degradation, NF-κB p65 phosphorylation and its nuclear translocation, and hydroxyl radical (OH°) productions in RAW 264.7 cells. However, the compounds TQ-1 and 2 had no effects in this study. TQ-4 also inhibited LPS-induced OH°p roduction. This study reveals the protective effect of TQ-4 against LPS-induced acute liver injury, inflammation, and oxidative reaction by destructing JNK/NF-κB signaling pathways. The result of this study may infer that TQ-4 might be a promising ruthenium metal derivative and/or therapeutic agent for treating liver injury.

TQ-6, a Novel Ruthenium Derivative Compound, Possesses Potent Free Radical Scavenging Activity in Macrophages and Rats

Applied Sciences, 2021

Reactive oxygen species (ROS) play major role in inducing inflammation and related diseases. Our previous studies have revealed that the ruthenium (II)-compound, [Ru(η6-cymene)2-(1H-benzoimidazol-2-yl)-quinoline Cl]BF4 (TQ-6), inhibits hydroxyl radical (OH•) formation in human platelets. TQ-6 also have protective effect against induced inflammation in macrophages and hepatic injury in mice through NF-κB signaling. However, the free radical formation inhibitory mechanism of TQ-6 in macrophages is unclear. Therefore, this study detected the antioxidative ability of TQ-6 in both a cell-free system and in LPS-induced macrophages through electron spin resonance (ESR) spectrometry. TQ-6 reduced 1,1-diphenyl-2-picrylhydrazyl (DPPH), galvinoxyl, and superoxide radicals in a cell-free system and OH• formation in macrophages. Additionally, TQ-6 activated the nuclear factor erythroid 2-related factor 2 (Nrf2) signaling pathway and upregulated the antioxidant protein heme oxygenase-1 (HO-1) to ...

LIVER X RECEPTOR AGONIST GW3965 DOSE-DEPENDENTLY REGULATES LPS-MEDIATED LIVER INJURY AND MODULATES POSTTRANSCRIPTIONAL TNF-α PRODUCTION AND P38 MITOGEN-ACTIVATED PROTEIN KINASE ACTIVATION IN LIVER MACROPHAGES

Shock, 2009

Modulation of the host inflammatory response to infection may be a key approach to improve the outcome of patients with sepsis and organ injury. We previously reported that pretreatment of rats with the liver X receptor (LXR) agonist GW3965 reduced the liver injury associated with endotoxemia and attenuated the production of TNF-! by rat Kupffer cells. Here, we examine the dose-dependent effect of GW3965 on liver injury and cytokine production in a rat model of endotoxemia and explore the mechanisms underlying TNF-! attenuation in Kupffer cells. Low doses of GW3965 (0.1 or 0.3 mg/kg) administered 30 min before infusion of LPS and peptidoglycan significantly attenuated the increase in plasma levels of the liver injury markers alanine aminotransferase and bilirubin (6 h) as well as the inflammatory mediators TNF-! (1 h) and prostaglandin E 2 (6 h) associated with endotoxemia. In contrast, pretreatment with a higher dose of GW3965 (1.0 mg/kg) had no such effect. Studies in primary cultures of rat Kupffer cells demonstrated that LXR agonist treatment attenuated both the secreted and cell-associated levels of TNF-!, whereas TNF-! mRNA levels were not altered. Phosphorylated p38 mitogen-activated protein kinase, which plays a major role in production of TNF-! at the posttranscriptional level, was attenuated by GW3965 treatment in Kupffer cells. Experiments in murine LXR-deficient Kupffer cells demonstrated enhanced production of TNF-! in Kupffer cells from LXR-! -/mice when challenged with LPS compared with LXR-" -/and wild-type Kupffer cells. Taken together, these results argue in favor of a novel mechanism for LXR-mediated attenuation of liver injury by interfering with posttranscriptional regulation of TNF-! in Kupffer cells.

An inhibitor of interaction between the transcription factor NRF2 and the E3 ubiquitin ligase adapter β-TrCP delivers anti-inflammatory responses in mouse liver

Redox Biology

It is widely accepted that activating the transcription factor NRF2 will blast the physiological anti-inflammatory mechanisms, which will help combat pathologic inflammation. Much effort is being put in inhibiting the main NRF2 repressor, KEAP1, with either electrophilic small molecules or disrupters of the KEAP1/NRF2 interaction. However, targeting β-TrCP, the non-canonical repressor of NRF2, has not been considered yet. After in silico screening of ~1 million compounds, we now describe a novel small molecule, PHAR, that selectively inhibits the interaction between β-TrCP and the phosphodegron in transcription factor NRF2. PHAR upregulates NRF2-target genes such as Hmox1, Nqo1, Gclc, Gclm and Aox1, in a KEAP1-independent, but β-TrCP dependent manner, breaks the β-TrCP/NRF2 interaction in the cell nucleus, and inhibits the β-TrCP-mediated in vitro ubiquitination of NRF2. PHAR attenuates hydrogen peroxide induced oxidative stress and, in lipopolysaccharide-treated macrophages, it downregulates the expression of inflammatory genes Il1b, Il6, Cox2, Nos2. In mice, PHAR selectively targets the liver and greatly attenuates LPS-induced liver inflammation as indicated by a reduction in the gene expression of the inflammatory cytokines Il1b, TNf, and Il6, and in F4/80-stained liver resident macrophages. Thus, PHAR offers a still unexplored alternative to current NRF2 activators by acting as a β-TrCP/NRF2 interaction inhibitor that may have a therapeutic value against undesirable inflammation.

GW4064 attenuates lipopolysaccharide‑induced hepatic inflammation and apoptosis through inhibition of the Toll‑like receptor 4‑mediated p38 mitogen‑activated protein kinase signaling pathway in mice

International Journal of Molecular Medicine

Liver injury is associated with devastating consequences caused by inflammation and apoptosis. The farnesoid X receptor (FXR) is a nuclear receptor that has an essential role in hepatoprotection by maintaining the homeostasis of liver metabolism. The present study investigated the capacity of the FXR agonist GW4064 to protect the livers of mice from lipopolysaccharide (LPS)-induced inflammation and apoptosis. Male C57BL/6J [wild-type (WT)] and FXR knockout (KO) mice were intraperitoneally injected with LPS or saline. LPS-treated mice were intraperitoneally injected with vehicle or GW4064 (20 mg/kg) twice and then sacrificed. Activation of FXR by GW4064 alleviated hepatic inflammation in the LPS-induced murine liver injury model as reflected by reduced serum levels of aspartate aminotransferase and pro-inflammatory cytokine mRNA expression, including tumor necrosis factor-α, as well as interleukin-6 and-1β in WT mice. In addition, Toll-like receptor 4 (TLR4), p38 mitogen-activated protein kinase (MAPK), B-cell lymphoma-2-associated X protein and cytochrome c protein levels were decreased in WT mice receiving LPS with simultaneous GW4064 administration compared with those receiving LPS alone, while this was not observed in FXR KO mice. These results indicated that in WT mice, administration of GW4064 ameliorated LPS-mediated liver injury by upregulation of FXR expression, which was in part mediated by the TLR4/p38 MAPK pathway.

The Role of Tumor Necrosis Factor Alpha in Lipopolysaccharide/Ranitidine-Induced Inflammatory Liver Injury

Toxicological Sciences, 2007

Exposure to a nontoxic dose of bacterial lipopolysaccharide (LPS) increases the hepatotoxicity of the histamine-2 (H2) receptor antagonist, ranitidine (RAN). Because some of the pathophysiologic effects associated with LPS are mediated through the expression and release of inflammatory mediators such as tumor necrosis factor alpha (TNF), this study was designed to gain insights into the role of TNF in LPS/RAN hepatotoxicity. To determine whether RAN affects LPS-induced TNF release at a time near the onset of liver injury, male Sprague-Dawley rats were treated with 2.5 3 10 6 endotoxin units (EU)/kg LPS or its saline vehicle (iv) and 2 h later with either 30 mg/kg RAN or sterile phosphate-buffered saline vehicle (iv). LPS administration caused an increase in circulating TNF concentration. RAN cotreatment enhanced the LPS-induced TNF increase before the onset of hepatocellular injury, an effect that was not produced by famotidine, a H2-receptor antagonist without idiosyncrasy liability. Similar effects were observed for serum interleukin (IL)-1beta, IL-6, and IL-10. To determine if TNF plays a causal role in LPS/RAN-induced hepatotoxicity, rats were given either pentoxifylline (PTX; 100 mg/kg, iv) to inhibit the synthesis of TNF or etanercept (Etan; 8 mg/kg, sc) to impede the ability of TNF to reach cellular receptors, and then they were treated with LPS and RAN. Hepatocellular injury, the release of inflammatory mediators, hepatic neutrophil (PMN) accumulation, and biomarkers of coagulation and fibrinolysis were assessed. Pretreatment with either PTX or Etan resulted in the attenuation of liver injury and diminished circulating concentrations of TNF, IL-1b, IL-6, macrophage inflammatory protein-2, and coagulation/ fibrinolysis biomarkers in LPS/RAN-cotreated animals. Neither PTX nor Etan pretreatments altered hepatic PMN accumulation. These results suggest that TNF contributes to LPS/RAN-induced liver injury by enhancing inflammatory cytokine production and hemostasis.

Rohitukine inhibits NF-κB activation induced by LPS and other inflammatory agents

International Immunopharmacology, 2019

Rohitukine (referred to as RHK) is a bioactive chromone alkaloid isolated from the leaves of plant Dysoxylum binectariferum, which has been reported to possess diverse pharmacological properties for the treatment of inflammatory bowel disease (IBD), diarrhoea and anti-lipidemic. However, the underlying mechanism by which RHK exerts its anti-inflammatory activity has not yet demonstrated. This study aimed to elucidate the antiinflammatory mechanism of RHK using lipopolysaccharide (LPS)-stimulated J774A.1 macrophage cells and invivo inflammatory models. Results demonstrated that RHK treatment could significantly decrease the LPS-induced production of nitric oxide, prostaglandin E2 (PGE2), interleukins (ILs) and tumour necrosis factor (TNF)-α in J774A.1 cells. Molecular studies revealed that RHK inhibited the activation of upstream mediator nuclear factor-κB by suppressing the phosphorylation of IκBα and p65. In in-vivo experiments showed prominent antiinflammatory activity of RHK. Thus, RHK could be considered as a promising candidate for the treatment of inflammatory diseases.

Liver Kinase B1 Suppresses Lipopolysaccharide-induced Nuclear Factor κB (NF-κB) Activation in Macrophages

Journal of Biological Chemistry, 2014

Background: LKB1 is a serine/threonine kinase that is essential in metabolism and tumor suppression. Results: LKB1 interacts with IKK␤ and suppresses NF-B activation in response to LPS. Conclusion: LKB1 inhibits LPS-induced inflammatory responses. Significance: This work reveals a novel mechanism for regulating LPS-induced inflammation. Liver kinase B1 (LKB1), a serine/threonine kinase, is a tumor suppressor and metabolic regulator. Recent data suggest that LKB1 is essential in regulating homeostasis of hematopoietic cells and immune responses. However, its role in macrophages and innate immune system remains unclear. Here we report that macrophage LKB1 inhibits pro-inflammatory signaling in response to LPS. LPS-induced pro-inflammatory cytokines and pro-inflammatory enzymes were monitored in bone marrowderived macrophages isolated from myeloid cell-specific LKB1 knock out mice and their wild type littermate control mice. LPS induced higher levels of pro-inflammatory cytokines and proinflammatory enzymes in bone marrow-derived macrophages from LKB1 KO than those from wild type mice. Consistently, LPS induced higher levels of NF-B activation in LKB1-deficient macrophages than those in wild type. Further, LPS stimulation significantly increased LKB1 phosphorylation at serine 428, which promoted its binding to IB kinase␤ (IKK␤), resulting in the inhibition of NF-B. Finally, LPS injection caused higher levels of cytokine release and more severe tissue injury in the lung tissues of LKB1 KO mice than in those of control mice. We conclude that LKB1 inhibits LPS-induced NF-B activation in macrophages.