Peroxynitrite induces HMGB1 release by cardiac cells in vitro and HMGB1 upregulation in the infarcted myocardium in vivo

Mitochondria as a source of reactive oxygen and nitrogen species: from molecular mechanisms to human health

Mitochondrially generated reactive oxygen species are involved in a myriad of signaling and damaging pathways in different tissues. In addition, mitochondria are an important target of reactive oxygen and nitrogen species. Here, we discuss basic mechanisms of mitochondrial oxidant generation and removal and the main factors affecting mitochondrial redox balance. We also discuss the interaction between mitochondrial reactive oxygen and nitrogen species, and the involvement of these oxidants in mitochondrial diseases, cancer, neurological, and cardiovascular disorders.

Propofol participates in gastric mucosal protection through inhibiting the toll-like receptor-4/nuclear factor kappa-B signaling pathway

AIMS

Propofol has demonstrated protective effects against digestive injury. Toll-like receptor-4 (TLR4) is involved in gastric mucosal injury. However, it has not yet been clarified whether propofol protects gastric mucosa from ethanol-induced injury and whether the mechanism involved is related to TLR4 activation. Therefore, this prospective study was carried out to address the issue.

METHODS

Gastric mucosal injury was induced in mice by intragastric administration of ethanol. Propofol was given intraperitoneally 30 min before ethanol intragastric administration and, 1h later, gastric specimens were studied using hematoxylin--eosin staining, quantitative real-time RT-PCR, immunohistochemical staining and Western blot assays; serum specimens were studied using ELISA kits.

RESULTS

Propofol at 25mg/kg significantly attenuated ethanol-induced gastric mucosal injury. In addition, propofol pretreatment significantly inhibited the upregulated expression of high-mobility group box-1 (HMGB1) protein, TLR4 and its downstream signaling molecules--myeloid differentiation factor 88 (MyD88) and nuclear factor kappa-B (NF-κB)--in gastric mucosa, while suppressing the increased release of tumor neurosis factor-α (TNF-α) and interleukin-1β (IL-1β) in serum. Furthermore, upregulation of the Bax/Bcl-2 ratio in gastric mucosa was clearly depressed by propofol.

CONCLUSION

Propofol can inhibit HMGB1 expression and TLR4/MyD88/NF-κB-mediated inflammatory responses, and hamper apoptosis, which may contribute to its protective action against ethanol-induced gastric mucosal injury.

Mitochondrial reactive oxygen species generation triggers inflammatory response and tissue injury associated with hepatic ischemia-reperfusion: therapeutic potential of mitochondrially targeted antioxidants

Mitochondrial reactive oxygen species generation has been implicated in the pathophysiology of ischemia-reperfusion (I/R) injury; however, its exact role and its spatial-temporal relationship with inflammation are elusive. Herein we explore the spatial-temporal relationship of oxidative/nitrative stress and inflammatory response during the course of hepatic I/R and the possible therapeutic potential of mitochondrial-targeted antioxidants, using a mouse model of segmental hepatic ischemia-reperfusion injury. Hepatic I/R was characterized by early (at 2 h of reperfusion) mitochondrial injury, decreased complex I activity, increased oxidant generation in the liver or liver mitochondria, and profound hepatocellular injury/dysfunction with acute proinflammatory response (TNF-α, MIP-1α/CCL3, MIP-2/CXCL2) without inflammatory cell infiltration, followed by marked neutrophil infiltration and a more pronounced secondary wave of oxidative/nitrative stress in the liver (starting from 6 h of reperfusion and peaking at 24 h). Mitochondrially targeted antioxidants, MitoQ or Mito-CP, dose-dependently attenuated I/R-induced liver dysfunction, the early and delayed oxidative and nitrative stress response (HNE/carbonyl adducts, malondialdehyde, 8-OHdG, and 3-nitrotyrosine formation), and mitochondrial and histopathological injury/dysfunction, as well as delayed inflammatory cell infiltration and cell death. Mitochondrially generated oxidants play a central role in triggering the deleterious cascade of events associated with hepatic I/R, which may be targeted by novel antioxidants for therapeutic advantage.

Cardioprotection with 8-O-acetyl shanzhiside methylester on experimental myocardial ischemia injury

8-O-acetyl shanzhiside methylester (ND01) was isolated from the leaves of Lamiophlomis rotata (Benth.) Kudo. In this study, we investigated the anti-myocardial ischemia and reperfusion (I/R) injury effects of ND01 in vivo and elucidated the potential mechanism in vitro. The results indicated that ND01 significantly attenuated hypoxia-induced cytotoxicity in a concentration-dependent manner in H9c2 cells. Treatment of H9c2 cells with ND01 9 μM blocked TNF-α-induced nuclear factor kappaB (NF-κB) phosphorylation by blocking High-mobility group box1 (HMGB1) expression. Treatment of rats with ND01 10mg/kg, (i.v.) protected the animals from myocardial I/R injury as indicated by a decrease in infarct volume, improvement in hemodynamics and reduction of myocardial damage severity. Treatment with ND01 also lowered serum levels of pro-inflammatory factors and reduced High mobility group box-1 protein (HMGB1) and phosphorylated NF-κB expression in ischemic myocardial tissue. Additionally, continuous i.v. of ND01 14 days attenuated cardiac remodeling. These protective effects suggested that ND01 might be due to block of myocardial inflammatory cascades through an HMGB1-dependent NF-κB signaling pathway.

Many stimuli pull the necrotic trigger, an overview

The lab of Jürg Tschopp was the first to report on the crucial role of receptor-interacting protein kinase 1 (RIPK1) in caspase-independent cell death. Because of this pioneer finding, regulated necrosis and in particular RIPK1/RIPK3 kinase-mediated necrosis, referred to as necroptosis, has become an intensively studied form of regulated cell death. Although necrosis was identified initially as a backup cell death program when apoptosis is blocked, it is now recognized as a cellular defense mechanism against viral infections and as being critically involved in ischemia-reperfusion damage. The observation that RIPK3 ablation rescues embryonic lethality in mice deficient in caspase-8 or Fas-associated-protein-via-a-death-domain demonstrates the crucial role of this apoptotic platform in the negative control of necroptosis during development. Here, we review and discuss commonalities and differences of the increasing list of inducers of regulated necrosis ranging from cytokines, pathogen-associated molecular patterns, to several forms of physicochemical cellular stress. Since the discovery of the crucial role of RIPK1 and RIPK3 in necroptosis, these kinases have become potential therapeutic targets. The availability of new pharmacological inhibitors and transgenic models will allow us to further document the important role of this form of cell death in degenerative, inflammatory and infectious diseases.

Cardioprotection of Asperosaponin X on experimental myocardial ischemia injury

BACKGROUND

Asperosaponin X was isolated from the roots of Dipsacus asper. In this study, we investigated the anti-myocardial ischemia and reperfusion (I/R) injury effects of Asperosaponin X in vivo and elucidated the potential mechanism in vitro.

RESULTS

Asperosaponin X significantly attenuated hypoxia-induced cytotoxicity in a concentration-dependent manner in H9c2 cells. Treatment of H9c2 cells with Asperosaponin X 5 μM or 10 μM blocked TNF-α-induced nuclear factor kappaB (NF-κB) phosphorylation by blocking HMGB1 expression. Treatment of rats with Asperosaponin X 10mg/kg, (i.v.) protected the animals from myocardial I/R injury as indicated by a decrease in infarct volume, improvement in hemodynamics and reduction of myocardial damage severity. Treatment with Asperosaponin X also lowered serum levels of pro-inflammatory factors and reduced High mobility group box-1 protein (HMGB1), phosphorylated IκB-α and NF-κB expression in ischemic myocardial tissue. Additionally, continuous i.v. of Asperosaponin X 14 days attenuated cardiac remodeling.

CONCLUSIONS

These protective effects suggested that Asperosaponin X may be due to block of myocardial inflammatory cascades through an HMGB1-dependent NF-κB signaling pathway.

Cannabidiol protects against hepatic ischemia/reperfusion injury by attenuating inflammatory signaling and response, oxidative/nitrative stress, and cell death

Ischemia/reperfusion (I/R) is a pivotal mechanism of liver damage after liver transplantation or hepatic surgery. We have investigated the effects of cannabidiol (CBD), the nonpsychotropic constituent of marijuana, in a mouse model of hepatic I/R injury. I/R triggered time-dependent increases/changes in markers of liver injury (serum transaminases), hepatic oxidative/nitrative stress (4-hydroxy-2-nonenal, nitrotyrosine content/staining, and gp91phox and inducible nitric oxide synthase mRNA), mitochondrial dysfunction (decreased complex I activity), inflammation (tumor necrosis factor α (TNF-α), cyclooxygenase 2, macrophage inflammatory protein-1α/2, intercellular adhesion molecule 1 mRNA levels; tissue neutrophil infiltration; nuclear factor κB (NF-κB) activation), stress signaling (p38MAPK and JNK), and cell death (DNA fragmentation, PARP activity, and TUNEL). CBD significantly reduced the extent of liver inflammation, oxidative/nitrative stress, and cell death and also attenuated the bacterial endotoxin-triggered NF-κB activation and TNF-α production in isolated Kupffer cells, likewise the adhesion molecule expression in primary human liver sinusoidal endothelial cells stimulated with TNF-α and attachment of human neutrophils to the activated endothelium. These protective effects were preserved in CB2 knockout mice and were not prevented by CB1/2 antagonists in vitro. Thus, CBD may represent a novel, protective strategy against I/R injury by attenuating key inflammatory pathways and oxidative/nitrative tissue injury, independent of classical CB1/2 receptors.