Reactive oxygen species in TNFalpha-induced signaling and cell death

Mitochondrial electron transport chain, ROS generation and uncoupling (Review)

The mammalian mitochondrial electron transport chain (ETC) includes complexes I-IV, as well as the electron transporters ubiquinone and cytochrome c. There are two electron transport pathways in the ETC: Complex I/III/IV, with NADH as the substrate and complex II/III/IV, with succinic acid as the substrate. The electron flow is coupled with the generation of a proton gradient across the inner membrane and the energy accumulated in the proton gradient is used by complex V (ATP synthase) to produce ATP. The first part of this review briefly introduces the structure and function of complexes I-IV and ATP synthase, including the specific electron transfer process in each complex. Some electrons are directly transferred to O₂ to generate reactive oxygen species (ROS) in the ETC. The second part of this review discusses the sites of ROS generation in each ETC complex, including sites I_F and I_Q in complex I, site II_F in complex II and site III_Qo in complex III, and the physiological and pathological regulation of ROS. As signaling molecules, ROS play an important role in cell proliferation, hypoxia adaptation and cell fate determination, but excessive ROS can cause irreversible cell damage and even cell death. The occurrence and development of a number of diseases are closely related to ROS overproduction. Finally, proton leak and uncoupling proteins (UCP_S) are discussed. Proton leak consists of basal proton leak and induced proton leak. Induced proton leak is precisely regulated and induced by UCPs. A total of five UCPs (UCP1-5) have been identified in mammalian cells. UCP1 mainly plays a role in the maintenance of body temperature in a cold environment through non-shivering thermogenesis. The core role of UCP2-5 is to reduce oxidative stress under certain conditions, therefore exerting cytoprotective effects. All diseases involving oxidative stress are associated with UCPs.

NF-κB-induced NOX1 activation promotes gastric tumorigenesis through the expansion of SOX2-positive epithelial cells

We previously showed that NADPH oxidase organizer 1 (Noxo1), a component of NADPH oxidase 1 (NOX1), is a TNF-α-induced tumor-promoting factor in gastric tumorigenesis. However, the mechanism of NOX1-induced reactive oxygen species (ROS) signaling for the gastric tumorigenesis has not been understood. Here, we showed that expression of NOX1 complex components, including Noxo1, but not other NOX family members was significantly upregulated in both mouse models for gastritis and gastric tumors, which was associated with increased ROS levels. We also found that NF-κB directly regulated NOXO1 expression in TNF-α-stimulated gastric cancer cells, suggesting that inflammation induces NOX1 complex activation through TNF-α/NF-κB pathway. Notably, in situ hybridization indicated that Noxo1 mRNA was detected in proliferating cells of gastritis and gastric tumors, and pharmacological inhibition of NOX activity significantly suppressed the proliferation of MKN45 gastric cancer cells and gastric hyperplasia of K19-C2mE mice. These results suggest that NOX1/ROS signaling has an important role in increased proliferation of stomach epithelial cells in the inflamed mucosa. Moreover, we found that expression of SOX2, a marker of gastric epithelial stem cells, was increased by NOX1/ROS signaling. Furthermore, disruption of Noxo1 in K19-C2mE mice significantly suppressed gastritis-associated metaplastic hyperplasia, a potent preneoplastic lesion, which was associated with decreased number of SOX2-positive cells. These results indicate that inflammation-induced Noxo1 expression is responsible for development of metaplastic hyperplasia in the stomach through an increase in SOX2-expressing undifferentiated epithelial cells. Therefore, inhibition of the NOX1/ROS signaling pathway is a possible strategy for prevention and therapy for gastric cancer development.

Comparative study of the differential cell death protecting effect of various ROS scavengers

Oxidative stress has for a long time been associated with cell death, especially classical necrosis, however, its role in other cell death pathways is less clear. Here, we evaluated in a comparative way, the effect of four different reactive oxygen species (ROS) scavengers, N-acetyl-L-cysteine (NAC), α-tocopherol and two superoxide dismutase mimetics, n(III)tetrakis(4-benzoic acid)porphyrin chloride, and 4-hydroxy-2,2,6,6-tetramethylpiperidine 1-oxyl (Tempol), in four different cell death models, including menadione-triggered necrosis, staurosporine-induced apoptosis and tumor necrosis factor (TNF)-induced apoptosis and necroptosis. While menadione-triggered necrosis was completely prevented by the classical ROS scavenger NAC and to a substantial amount by the other scavengers, ROS targeting was found to have a marginal effect on the other cell death modalities investigated. Despite its side-effects at higher concentrations, Tempol was able to substantially prevent TNF-induced apoptosis and to a somewhat lesser extent TNF-induced necroptosis. However, this seems to be separated from its ROS-scavenging function.

Cycloartane-type sapogenol derivatives inhibit NFκB activation as chemopreventive strategy for inflammation-induced prostate carcinogenesis

Chronic inflammation is associated to 25% of cancer cases according to epidemiological data. Therefore, inhibition of inflammation-induced carcinogenesis can be an efficient therapeutic approach for cancer chemoprevention in drug development studies. It is also determined that anti-inflammatory drugs reduce cancer incidence. Cell culture-based in vitro screening methods are used as a fast and efficient method to investigate the biological activities of the biomolecules. In addition, saponins are molecules that are isolated from natural sources and are known to have potential for tumor inhibition. Studies on the preparation of analogues of cycloartane-type sapogenols (9,19-cyclolanostanes) have so far been limited. Therefore we have decided to direct our efforts toward the exploration of new anti-tumor agents prepared from cycloastragenol and its production artifact astragenol. The semi-synthetic derivatives were prepared mainly by oxidation, condensation, alkylation, acylation, and elimination reactions. After preliminary studies, five sapogenol analogues, two of which were new compounds (2 and 3), were selected and screened for their inhibitory activity on cell viability and NFκB signaling pathway activity in LNCaP prostate cancer cells. We found that the astragenol derivatives 1 and 2 as well as cycloastragenol derivatives 3, 4, and 5 exhibited strong inhibitory activity on NFκB signaling leading the repression of NFκB transcriptional activation and suppressed cell proliferation. The results suggested that these molecules might have significant potential for chemoprevention of prostate carcinogenesis induced by inflammatory NFκB signaling pathway.

Antitumor Effect of Japanese Apricot Extract (MK615) on Human Cancer Cells in Vitro and in Vivo through a Reactive Oxygen Species-Dependent Mechanism

Aims and background

MK615 is produced from Japanese apricot and contains several cyclic triterpenes, such as oleanolic and ursolic acids. MK615 was shown to strongly suppress cutaneous in-transit metastasis in a patient with malignant melanoma. The present investigation was undertaken to clarify the antitumor effects of MK615 in vitro and in vivo.

Methods

Several human cancer cell lines were exposed to MK615 for 7 days to examine its antiproliferative effects. The effect of MK615 on in vivo growth of human pancreatic cancer MIAPaCa-2 cells was also examined.

Results

MK615 inhibited the growth of several human cancer cell lines in a concentration-dependent way. Pancreatic cancer MIAPaCa-2 cells were highly sensitive to the growth-inhibiting effects of MK615. Treatment with MK615 preferentially induced cell death in human cancer cells while sparing normal cells such as human umbilical vein endothelial cells (HUVEC) and mouse bone marrow cells. When MIAPaCa-2 cells were incubated with MK615 in the presence of antioxidant, growth-inhibition was significantly reduced, and MK615 induced the accumulation of reactive oxygen species in cancer cells but not in HUVEC. MK615, in both the presence and absence of gemcitabine, significantly inhibited the growth of human pancreatic cancer cells as xenografts without apparent adverse effects.

Conclusions

MK615, a supplement produced from Japanese apricot, may have therapeutic value in treating human cancers through a reactive oxygen species-dependent mechanism.

The caspase-8/Bid/cytochrome c axis links signals from death receptors to mitochondrial reactive oxygen species production

Ligation of the death receptors for TNF-α, FasL, and TRAIL triggers two common pathways, caspase-dependent intrinsic apoptosis and intracellular reactive oxygen species (ROS) generation. The apoptotic pathway is well characterized; however, a signaling linker between the death receptor and ROS production has not been clearly elucidated. Here, we found that death receptor-induced ROS generation was strongly inhibited by mitochondrial complex I and II inhibitors, but not by inhibitors of NADPH oxidase, lipoxygenase, cyclooxygenase or xanthine oxidase, indicating that ROS are mostly generated by the impairment of the mitochondrial respiratory chain. ROS generation was accompanied by caspase-8 activation, Bid cleavage, and cytochrome c release; it was blocked in FADD- and caspase-8-deficient cells, as well as by caspase-8 knockdown and inhibitor. Moreover, Bid knockdown abrogated TNF-α- or TRAIL-induced ROS generation, whereas overexpression of truncated Bid (tBid) or knockdown of cytochrome c spontaneously elevated ROS production. In addition, p53-overexpressing cells accumulated intracellular ROS via cytochrome c release mediated by the BH3-only protein Noxa induction. In a cell-free reconstitution system, caspase-8-mediated Bid cleavage and recombinant tBid induced mitochondrial cytochrome c release and ROS generation, which were blocked by Bcl-xL and antioxidant enzymes. These data suggest that anti-apoptotic Bcl-2 proteins play an important role in mitochondrial ROS generation by preventing cytochrome c release. These data provide evidence that the FADD/caspase-8/Bid/cytochrome c axis is a crucial linker between death receptors and mitochondria, where they play a role in ROS generation and apoptosis.

A Proteomic-Based Approach to Study the Mechanism of Cytotoxicity Induced by Interleukin-1α and Cycloheximide

Abstract

The exposure of HeLa cells to interleukin-1 alpha (IL-1α) in the presence of cycloheximide (CHX) leads to the release of active tumor necrosis factor alpha (TNF-α), eliciting cytocidal effect on these cells. A mass spectrometry (MS)-based analysis of the qualitative proteomic profiles of the HeLa cells treated only with IL-1α, CHX or simultaneously with IL-1α and CHX, in comparison to an untreated control, enabled to distinguish protein candidates possibly involved in this process. Among them protein disulphide isomerase (PDI) seemed to be particularly interesting for further research. Therefore, we focused on quantitative changes of PDI levels in HeLa cells subjected to IL-1α and CHX. Enzyme-linked immunosorbent assay (ELISA) was employed for determination of PDI concentrations in the investigated, differently treated HeLa cells. The obtained results confirmed up-regulation of PDI only in the cells stimulated with IL-1α alone. In contrary, the PDI levels in HeLa cells exposed to both IL-1α and CHX, where apoptotic process was intensive, did not increase significantly. Finally, we discuss how different expression levels of PDI together with other proteins, which were detected in this study, may influence the induction of cytotoxic effect and modulate sensitivity to cytotoxic action of IL1.

Graphical Abstract

Electronic supplementary material

The online version of this article (doi:10.1007/s10337-017-3382-3) contains supplementary material, which is available to authorized users.

Role of Surface Hydrophobicity of Dicationic Amphiphile-Stabilized Gold Nanoparticles on A549 Lung Cancer Cells

Herein, we report the surface functionality of dicationic cysteamine conjugated cholic acid (DCaC), dicationic cysteamine conjugated deoxycholic acid (DCaDC), and dicationic cysteamine conjugated lithocholic acid (DCaLC) templated gold nanoparticles (AuNPs) on mammalian cells. The haemocompatibility of the synthesized NPs was evaluated by in vitro hemolysis and erythrocyte sedimentation rate using human red blood cells (RBCs). In all of the systems, no toxicity was observed on human erythrocytes (RBCs) up to the concentration of 120 μg/mL. The anticancer activity of these dicationic amphiphile-stabilized AuNPs on A549 lung cancer cells was demonstrated by in vitro cell viability assay, intracellular reactive oxygen species estimation by DCFH-DA, apoptosis analysis using AO-EtBr fluorescence staining, DNA fragmentation analysis by agarose gel electrophoresis, and western blot analysis of caspase-3 expression. These results suggest that the cytotoxicity of AuNPs to A549 cells increase with the dose and hydrophobicity of amphiphiles and were found to be in the order: DCaLC-AuNPs > DCaDC-AuNPs > DCaC-AuNPs.

Regulation of necroptosis signaling and cell death by reactive oxygen species

Necroptosis has recently been identified as an alternative form of programmed cell death that is characterized by defined molecular mechanisms. Reactive oxygen species (ROS) are involved in the regulation of numerous signaling pathways, as they are highly reactive and can cause (ir)reversible posttranslational modifications. While the role of ROS in other modes of cell death has been extensively studied, its impact on necroptotic signaling and cell death is far less clear. The current minireview discusses the evidence for and against a role of ROS in necroptosis.

A novel damage mechanism: Contribution of the interaction between necroptosis and ROS to high glucose-induced injury and inflammation in H9c2 cardiac cells

Recently, a novel mechanism known as 'programmed necrosis' or necroptosis has been shown to be another important mechanism of cell death in the heart. In this study, we investigated the role of necroptosis in high glucose (HG)-induced injury and inflammation, as well as the underlying mechanisms. In particular, we focused on the interaction between necroptosis and reactive oxygen species (ROS) in H9c2 cardiac cells. Our results demonstrated that the exposure of H9c2 cardiac cells to 35 mM glucose (HG) markedly enhanced the expression level of receptor-interacting protein 3 (RIP3), a kinase which promotes necroptosis. Importantly, co-treatment of the cells with 100 µM necrostatin-1 (a specific inhibitor of necroptosis) and HG for 24 h attenuated not only the increased expression level of RIP3, but also the HG-induced injury and inflammation, as evidenced by an increase in cell viability, a decrease in ROS generation, the attenuation of the dissipation of mitochondrial membrane potential and a decrese in the secretion levels of inflammatory cytokines, i.e., interleukin (IL)-1β and tumor necrosis factor (TNF)-α. Furthermore, treatment of the cells with 1 mM N-acetyl‑L‑cysteine (a scavenger of ROS) for 60 min prior to exposure to HG significantly reduced the HG-induced increase in the RIP3 expression level, as well as the injury and inflammatory response described above. Taken together, the findings of this study clearly demonstrate a novel damage mechanism involving the positive interaction between necroptosis and ROS attributing to HG-induced injury and inflammation in H9c2 cardiac cells.

Establishment of HK-2 Cells as a Relevant Model to Study Tenofovir-Induced Cytotoxicity

Tenofovir (TFV) is an antiviral drug approved for treating Human Immunodeficiency Virus (HIV) and Hepatitis B. TFV is administered orally as the prodrug tenofovir disoproxil fumarate (TDF) which then is deesterified to the active drug TFV. TFV induces nephrotoxicity characterized by renal failure and Fanconi Syndrome. The mechanism of this toxicity remains unknown due to limited experimental models. This study investigated the cellular mechanism of cytotoxicity using a human renal proximal tubular epithelial cell line (HK-2). HK-2 cells were grown for 48 h followed by 24 to 72 h exposure to 0–28.8 μM TFV or vehicle, phosphate buffered saline (PBS). MTT (MTT, 3-(4,5-dimethylthiazol-2-yl)-2,5-Diphenyltetrazolium Bromide) and Trypan blue indicated that TFV diminished cell viability at 24–72 h. TFV decreased ATP levels at 72 h when compared to vehicle, reflecting mitochondrial dysfunction. TFV increased the oxidative stress biomarkers of protein carbonylation and 4-hydroxynonenol (4-HNE) adduct formation. Tumor necrosis factor alpha (TNFα) was released into the media following exposure to 14.5 and 28.8 μM TFV. Caspase 3 and 9 cleavage was induced by TFV compared to vehicle at 72 h. These studies show that HK-2 cells are a sensitive model for TFV cytotoxicity and suggest that mitochondrial stress and apoptosis occur in HK-2 cells treated with TFV.

Increased mitochondrial ROS generation mediates the loss of the anti-contractile effects of perivascular adipose tissue in high-fat diet obese mice

BACKGROUND AND PURPOSE

Obesity is associated with structural and functional changes in perivascular adipose tissue (PVAT), favouring release of reactive oxygen species (ROS), vasoconstrictor and proinflammatory factors. The cytokine TNF-α induces vascular dysfunction and is produced by PVAT. We tested the hypothesis that obesity-associated PVAT dysfunction was mediated by augmented mitochondrial ROS (mROS) generation due to increased TNF-α production in this tissue.

EXPERIMENTAL APPROACH

C57Bl/6J and TNF-α receptor-deficient mice received control or high fat diet (HFD) for 18 weeks. We used pharmacological tools to determine the participation of mROS in PVAT dysfunction. Superoxide anion (O₂^.- ) and H₂ O₂ were assayed in PVAT and aortic rings were used to assess vascular function.

KEY RESULTS

Aortae from HFD-fed obese mice displayed increased contractions to phenylephrine and loss of PVAT anti-contractile effect. Inactivation of O₂^.- , dismutation of mitochondria-derived H₂ O₂ , uncoupling of oxidative phosphorylation and Rho kinase inhibition, decreased phenylephrine-induced contractions in aortae with PVAT from HFD-fed mice. O₂^.- and H₂ O₂ were increased in PVAT from HFD-fed mice. Mitochondrial respiration analysis revealed decreased O₂ consumption rates in PVAT from HFD-fed mice. TNF-α inhibition reduced H₂ O₂ levels in PVAT from HFD-fed mice. PVAT dysfunction, i.e. increased contraction to phenylephrine in PVAT-intact aortae, was not observed in HFD-obese mice lacking TNF-α receptors. Generation of H₂ O₂ was prevented in PVAT from TNF-α receptor deficient obese mice.

CONCLUSION AND IMPLICATIONS

TNF-α-induced mitochondrial oxidative stress is a key and novel mechanism involved in obesity-associated PVAT dysfunction. These findings elucidate molecular mechanisms whereby oxidative stress in PVAT could affect vascular function.

LINKED ARTICLES

This article is part of a themed section on Molecular Mechanisms Regulating Perivascular Adipose Tissue - Potential Pharmacological Targets? To view the other articles in this section visit http://onlinelibrary.wiley.com/doi/10.1111/bph.v174.20/issuetoc.

Recent advances in understanding the role of adipocytokines during non-alcoholic fatty liver disease pathogenesis and their link with hepatokines

Non-alcoholic fatty liver disease (NAFLD) is currently considered the main cause of chronic liver disease worldwide. Mechanisms leading to the development and progression of this disease are topics of great interest for researchers and clinicians. The current multi-hit hypothesis has thrown the crosstalk between liver and adipose tissue into sharp focus. It is well known that adipose tissue produces circulating factors, known as adipocytokines, which exert several effects on liver cells, promoting the onset of NAFLD and its progression to non-alcoholic steatohepatitis in obese subjects. In a similar way, hepatocytes may also respond to obesogenic stimuli by producing and releasing hepatokines into the circulation. Here, the authors provide an overview of recent advances in our understanding of the role of the most relevant adipocytokines and hepatokines in NAFLD pathogenesis, highlighting their possible molecular and functional interactions.

Phytanic acid activates NADPH oxidase through transactivation of epidermal growth factor receptor in vascular smooth muscle cells

BACKGROUND

Phytanic acid (PA) has been implicated in development of cancer and its defective metabolism is known to cause life-threatening conditions, such as Refsum disease, in children. To explore molecular mechanisms of phytanic acid-induced cellular pathology, we investigated its effect on NADPH oxidase (NOX) and epidermal growth factor receptor (EGFR) in rat aortic smooth muscle cells (RASMC).

METHODS

Smooth muscle cells were isolated from rat aortae using enzymic digestion with collagenase and elastase. Cultured RASMC were treated with varying concentrations (0.5-10 μg/ml) of phytanic acid in the presence/absence of fetal bovine serum (FBS) and/or EGFR inhibitor, AG1478. Following treatment with experimental agents, NOX activity was assayed in RASMC cultures by luminescence method. Gene expression of NOX-1 and p47phox was assessed using RT-PCR. NOX-1, p47phox and, total EGFR protein and its phosphorylated form were measured by Western blotting.

RESULTS

Treatment of RASMC with supraphysiological concentrations (>2.5 μg/ml) of PA significantly (p < 0.01) increased the NOX activity. PA also significantly increased gene/protein expression of NOX-1 and p47phox whereas p22phox and p67phox remained unaffected. Interestingly, PA (2.5-10 μg/ml) markedly (2-3 folds) increased the total and phosphorylated EGFR. Treatment of cells with EGFR inhibitor, AG1478, significantly blocked the PA-induced enhancement of NOX activity.

CONCLUSIONS

Our findings that PA transactivates EGFR and induces NOX activity in vascular smooth muscle cells provide new insights into molecular mechanisms of PA's role in cancer and Refsum disease.

The serine threonine kinase RIP3: lost and found

Receptor-interacting protein kinase-3 (RIP3, or RIPK3) is an essential protein in the "programmed", or "regulated" necrosis cell death pathway that is activated in response to death receptor ligands and other types of cellular stress. Programmed necrotic cell death is distinguished from its apoptotic counterpart in that it is not characterized by the activation of caspases; unlike apoptosis, programmed necrosis results in plasma membrane rupture, thus spilling the contents of the cell and triggering the activation of the immune system and inflammation. Here we discuss findings, including our own recent data, which show that RIP3 protein expression is absent in many cancer cell lines. The recent data suggests that the lack of RIP3 expression in a majority of these deficient cell lines is due to methylation-dependent silencing, which limits the responses of these cells to pro-necrotic stimuli. Importantly, RIP3 expression may be restored in many cancer cells through the use of hypomethylating agents, such as decitabine. The potential implications of loss of RIP3 expression in cancer are explored, along with possible consequences for chemotherapeutic response.

Allicin inhibits oxidative stress-induced mitochondrial dysfunction and apoptosis by promoting PI3K/AKT and CREB/ERK signaling in osteoblast cells

Osteoporosis is a disease of the skeleton that is characterized by the loss of bone mass and degeneration of bone microstructure, resulting in an increased risk of fracture. Oxidative stress, which is known to promote oxidative damage to mitochondrial function and also cell apoptosis, has been recently indicated to be implicated in osteoporosis. However, there are few agents that counteract oxidative stress in osteoporosis. In the present study, the protective effects of allicin against the oxidative stress-induced mitochondrial dysfunction and apoptosis were investigated in murine osteoblast-like MC3T3-E1 cells. The results demonstrated that allicin counteracted the reduction of cell viability and induction of apoptosis caused by hydrogen peroxide (H₂O₂) exposure. The inhibition of apoptosis by allicin was confirmed by the inhibition of H₂O₂-induced cytochrome c release and caspase-3 activation. Moreover, the inhibition of apoptosis by allicin was identified to be associated with the counteraction of H₂O₂-induced mitochondrial dysfunction. In addition, allicin was demonstrated to be able to significantly ameliorate the repressed phosphoinositide 3-kinase (PI3K)/AKT and cyclic adenosine monophosphate response element-binding protein (CREB)/extracellular-signal-regulated kinase (ERK) signaling pathways by H₂O₂, which may also be associated with the anti-oxidative stress effects of allicin. In conclusion, allicin protects osteoblasts from H₂O₂-induced oxidative stress and apoptosis in MC3T3-E1 cells by improving mitochondrial function and the activation of PI3K/AKT and CREB/ERK signaling. The present study implies a promising role of allicin in oxidative stress-associated osteoporosis.

TNF-α Inhibits FoxO1 by Upregulating miR-705 to Aggravate Oxidative Damage in Bone Marrow-Derived Mesenchymal Stem Cells during Osteoporosis

Decline of antioxidant defense after estrogen deficiency leads to oxidative damage in bone marrow-derived mesenchymal stem cells (BMMSCs), resulting a defect of bone formation in osteoporosis. Forkhead box O1 (FoxO1) protein is crucial for defending physiological oxidative damage in bone. But whether FoxO1 is involved in the oxidative damage during osteoporosis is largely unknown. In this study, we found that FoxO1 protein accumulation was decreased in BMMSCs of ovariectomized mice. The decrease of FoxO1 resulted in the suppression of manganese superoxide dismutase (Sod2) and catalase (Cat) expression and accumulation of reactive oxygen species (ROS), inhibiting the osteogenic differentiation of BMMSCs. The decline of FoxO1 protein was caused by tumor necrosis factor-alpha (TNF-α) accumulated after estrogen deficiency. Mechanistically, TNF-α activated NF-κB pathway to promote microRNA-705 expression, which function as a repressor of FoxO1 through post-transcriptional regulation. Inhibition of NF-κB pathway or knockdown of miR-705 largely prevented the decline of FoxO1-mediated antioxidant defense caused by TNF-α and ameliorated the oxidative damage in osteoporotic BMMSCs. Moreover, the accumulated ROS further activated NF-κB pathway with TNF-α, which formed a feed-forward loop to persistently inhibiting FoxO1 protein accumulation in BMMSCs. In conclusion, our study revealed that the decline of FoxO1 is an important etiology factor of osteoporosis and unclosed a novel mechanism of FoxO1 regulation by TNF-α. These findings suggested a close correlation between inflammation and oxidative stress in stem cell dysfunction during degenerative bone diseases.

Nilotinib reduced the viability of human ovarian cancer cells via mitochondria-dependent apoptosis, independent of JNK activation

Nilotinib (AMN) induces apoptosis in various cancer cells; however the effect of AMN on human ovarian cancer cells is still unclear. A reduction in cell viability associated with the occurrence of apoptotic characteristics was observed in human SKOV-3 ovarian cancer cells under AMN but not sorafenib (SORA) or imatinib (STI) stimulation. Activation of apoptotic pathway including increased caspase (Casp)-3 and poly(ADP-ribose) polymerase 1 (PARP1) protein cleavage by AMN was detected with disrupted mitochondrial membrane potential (MMP) accompanied by decreased Bcl-2 protein and increased cytosolic cytochrome (Cyt) c/cleaved Casp-9 protein expressions was found, and AMN-induced cell death was inhibited by peptidyl Casp inhibitors, VAD, DEVD and LEHD. Increased phosphorylated c-Jun N-terminal kinase (JNK) protein expression was detected in AMN- but not SORA- or STI-treated SKOV-3 cells, and the JNK inhibitors, SP600125 and JNKI, showed slight but significant enhancement of AMN-induced cell death in SKOV-3 cells. The intracellular peroxide level was elevated by AMN and H2O2, and N-acetylcysteine (NAC) prevented H2O2- but not AMN-induced peroxide production and apoptosis in SKOV-3 cells. AMN induction of apoptosis with increased intracellular peroxide production and JNK protein phosphorylation was also identified in human A2780 ovarian cancer cells, cisplatin-resistant A2780CP cells, and clear ES-2 cells. The evidence supporting AMN effectively reducing the viability of human ovarian cancer cells via mitochondrion-dependent apoptosis is provided.

β-Catenin is central to DUX4-driven network rewiring in facioscapulohumeral muscular dystrophy

Facioscapulohumeral muscular dystrophy (FSHD) is an incurable disease, characterized by skeletal muscle weakness and wasting. Genetically, FSHD is characterized by contraction or hypomethylation of repeat D4Z4 units on chromosome 4, which causes aberrant expression of the transcription factor DUX4 from the last repeat. Many genes have been implicated in FSHD pathophysiology, but an integrated molecular model is currently lacking. We developed a novel differential network methodology, Interactome Sparsification and Rewiring (InSpiRe), which detects network rewiring between phenotypes by integrating gene expression data with known protein interactions. Using InSpiRe, we performed a meta-analysis of multiple microarray datasets from FSHD muscle biopsies, then removed secondary rewiring using non-FSHD datasets, to construct a unified network of rewired interactions. Our analysis identified β-catenin as the main coordinator of FSHD-associated protein interaction signalling, with pathways including canonical Wnt, HIF1-α and TNF-α clearly perturbed. To detect transcriptional changes directly elicited by DUX4, gene expression profiling was performed using microarrays on murine myoblasts. This revealed that DUX4 significantly modified expression of the genes in our FSHD network. Furthermore, we experimentally confirmed that Wnt/β-catenin signalling is affected by DUX4 in murine myoblasts. Thus, we provide the first unified molecular map of FSHD signalling, capable of uncovering pathomechanisms and guiding therapeutic development.

Modulating the Innate Immune Response to Influenza A Virus: Potential Therapeutic Use of Anti-Inflammatory Drugs

Infection by influenza A viruses (IAV) is frequently characterized by robust inflammation that is usually more pronounced in the case of avian influenza. It is becoming clearer that the morbidity and pathogenesis caused by IAV are consequences of this inflammatory response, with several components of the innate immune system acting as the main players. It has been postulated that using a therapeutic approach to limit the innate immune response in combination with antiviral drugs has the potential to diminish symptoms and tissue damage caused by IAV infection. Indeed, some anti-inflammatory agents have been shown to be effective in animal models in reducing IAV pathology as a proof of principle. The main challenge in developing such therapies is to selectively modulate signaling pathways that contribute to lung injury while maintaining the ability of the host cells to mount an antiviral response to control virus replication. However, the dissection of those pathways is very complex given the numerous components regulated by the same factors (i.e., NF kappa B transcription factors) and the large number of players involved in this regulation, some of which may be undescribed or unknown. This article provides a comprehensive review of the current knowledge regarding the innate immune responses associated with tissue damage by IAV infection, the understanding of which is essential for the development of effective immunomodulatory drugs. Furthermore, we summarize the recent advances on the development and evaluation of such drugs as well as the lessons learned from those studies.

Programmed cell death with a necrotic-like phenotype

Programmed cell death is the process by which an individual cell in a multicellular organism commits cellular 'suicide' to provide a long-term benefit to the organism. Thus, programmed cell death is important for physiological processes such as development, cellular homeostasis, and immunity. Importantly, in this process, the cell is not eliminated in response to random events but in response to an intricate and genetically defined set of internal cellular molecular events or 'program'. Although the apoptotic process is generally very well understood, programmed cell death that occurs with a necrotic-like phenotype has been much less studied, and it is only within the past few years that the necrotic program has begun to be elucidated. Originally, programmed necrosis was somewhat dismissed as a nonphysiological phenomenon that occurs in vitro. Recent in vivo studies, however, suggest that regulated necrosis is an authentic classification of cell death that is important in mammalian development and other physiological processes, and programmed necrosis is now considered a significant therapeutic target in major pathological processes as well. Although the RIP1-RIP3-dependent necrosome complex is recognized as being essential for the execution of many instances of programmed necrosis, other downstream and related necrotic molecules and pathways are now being characterized. One of the current challenges is understanding how and under what conditions these pathways are linked together.

The redox biology network in cancer pathophysiology and therapeutics

The review pinpoints operational concepts related to the redox biology network applied to the pathophysiology and therapeutics of solid tumors. A sophisticated network of intrinsic and extrinsic cues, integrated in the tumor niche, drives tumorigenesis and tumor progression. Critical mutations and distorted redox signaling pathways orchestrate pathologic events inside cancer cells, resulting in resistance to stress and death signals, aberrant proliferation and efficient repair mechanisms. Additionally, the complex inter-cellular crosstalk within the tumor niche, mediated by cytokines, redox-sensitive danger signals (HMGB1) and exosomes, under the pressure of multiple stresses (oxidative, inflammatory, metabolic), greatly contributes to the malignant phenotype. The tumor-associated inflammatory stress and its suppressive action on the anti-tumor immune response are highlighted. We further emphasize that ROS may act either as supporter or enemy of cancer cells, depending on the context. Oxidative stress-based therapies, such as radiotherapy and photodynamic therapy, take advantage of the cytotoxic face of ROS for killing tumor cells by a non-physiologically sudden, localized and intense oxidative burst. The type of tumor cell death elicited by these therapies is discussed. Therapy outcome depends on the differential sensitivity to oxidative stress of particular tumor cells, such as cancer stem cells, and therefore co-therapies that transiently down-regulate their intrinsic antioxidant system hold great promise. We draw attention on the consequences of the damage signals delivered by oxidative stress-injured cells to neighboring and distant cells, and emphasize the benefits of therapeutically triggered immunologic cell death in metastatic cancer. An integrative approach should be applied when designing therapeutic strategies in cancer, taking into consideration the mutational, metabolic, inflammatory and oxidative status of tumor cells, cellular heterogeneity and the hypoxia map in the tumor niche, along with the adjoining and systemic effects of oxidative stress-based therapies.

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Critical point mutations and distorted redox-sensitive signaling pathways underlie the tumorigenic phenotype.

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Inter-cellular crosstalk under stress conditions in the tumor niche drives the behavior of tumor cells.

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ROS may act as either as supporter or enemy of tumor cells, depending on the context.

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Oxidative stress-injured cells deliver danger signals to neighboring and distant cells, hence dictating the outcome of therapy in cancer.

Myeloperoxidase genetic polymorphisms and susceptibility to Kawasaki disease in Taiwanese children

BACKGROUND/PURPOSE

The aim of this study was to investigate the myeloperoxidase (MPO) -463G>A polymorphism in Kawasaki disease (KD) patients, and the relationship between gene polymorphism and MPO levels.

METHODS

A total of 334 KD children and 492 sex-matched controls were assayed for polymorphism analysis. TaqMan assays were used for genotyping. MPO was measured in 37 KD patients and 42 febrile controls.

RESULTS

A significant linear trend of KD risk was found to be related to the G/G genotype (p_{linear trend} = 0.032). The combined genotypes (G/A and A/A) of MPO -463G>A were associated with a significantly decreased KD risk compared to the G/G genotype [adjusted odds ratios (AOR) = 0.71, 95% confidence interval (CI): 0.52-0.99, p = 0.040]. In addition, KD patients with A allele were associated with a significantly decreased KD risk as compared to those with G allele (AOR = 0.73, 95% CI: 0.54-0.98, p = 0.033). MPO levels were significantly elevated in KD patients in preintravenous immunoglobulin (pre-IVIG) stage compared to febrile controls (p = 0.002). KD patients in pre-IVIG stage had significantly higher MPO levels than febrile controls in terms of G/G genotype (p = 0.003) and G allele (p < 0.001). KD patients with A allele had significantly lower MPO levels than those with G allele in post-IVIG acute stage (p = 0.042). However, there was no significant difference of individual MPO change for KD patients from pre- to post-IVIG stage in terms of genotypes (p = 0.837) or alleles (p = 0.631).

CONCLUSION

Our results suggest that G allele of MPO -463G>A polymorphism is a potential genetic marker for KD risk in Taiwanese children.

Chronic inflammation aggravates metabolic disorders of hepatic fatty acids in high-fat diet-induced obese mice

The prevalence of nonalcoholic fatty liver disease (NAFLD) increases with increasing body mass index (BMI). However, approximately 40–50% of obese adults do not develop hepatic steatosis. The level of inflammatory biomarkers is higher in obese subjects with NAFLD compared to BMI-matched subjects without hepatic steatosis. We used a casein injection in high-fat diet (HFD)-fed C57BL/6J mice to induce inflammatory stress. Although mice on a HFD exhibited apparent phenotypes of obesity and hyperlipidemia regardless of exposure to casein injection, only the HFD+Casein mice showed increased hepatic vacuolar degeneration accompanied with elevated inflammatory cytokines in the liver and serum, compared to mice on a normal chow diet. The expression of genes related to hepatic fatty acid synthesis and oxidation were upregulated in the HFD-only mice. The casein injection further increased baseline levels of lipogenic genes and decreased the levels of oxidative genes in HFD-only mice. Inflammatory stress induced both oxidative stress and endoplasmic reticulum stress in HFD-fed mice livers. We conclude that chronic inflammation precedes hepatic steatosis by disrupting the balance between fatty acid synthesis and oxidation in the livers of HFD-fed obese mice. This mechanism may operate in obese individuals with chronic inflammation, thus making them more prone to NAFLD.

The human Nox4: gene, structure, physiological function and pathological significance

Increased generation of reactive oxygen species (ROS) has been implicated in the pathogenesis of a variety of diseases such as cardiovascular diseases and cancer. NADPH oxidase (Nox), a multicomponent enzyme, has been identified as one of the key sources of ROS. Nox4, one of the seven members of Nox family (Nox1, Nox2, Nox3, Nox4, Nox5, Duox1 and Duox2), has been extensively investigated in recent years. Its unique structures result in the constitutive generation of hydrogen peroxide (H2O2) as the main product. As a key oxygen sensor, Nox4-derived H2O2 plays diverse roles in cell proliferation, migration and death. Increased expression of Nox4 in cancer has been observed, which participates in metastasis, angiogenesis and apoptosis. Expression of Nox4 in endothelial cells actively mediated endothelial activation, dysfunction and injury, which contributes to the development of atherosclerosis, hypertension, cardiac hypertrophy and among others. This article explores the experimental studies related to the gene, structure, physiological function and pathological significance of Nox4. As Nox4 might serve as a potential target for the therapy of cardiovascular diseases and cancer, the Nox4 inhibitor is also discussed in this article.

C/EBP homologous protein (CHOP) contributes to hepatocyte death via the promotion of ERO1α signalling in acute liver failure

CCAAT/enhancer binding protein (C/EBP)-homologous protein (CHOP) has been shown to be a key molecule in endoplasmic reticulum (ER) stress-mediated apoptosis. ER oxidoreductin 1-α (ERO1α), a target of CHOP, is an important oxidizing enzyme that regulates reactive oxygen species (ROS), which play a prominent role in hepatocellular death during acute liver failure (ALF). However, little is known about how CHOP facilitates ROS-induced hepatocellular injury. The present study was designed to investigate the roles and molecular mechanisms of CHOP in ALF. In the liver tissues from ALF patients, the expression of CHOP was significantly increased, which was accompanied by increased expression of dsRNA-dependent protein kinase (PKR)-like ER kinase (PERK) signalling, activating transcription factor 4 (ATF6) signalling, inositol-requiring enzyme-1 (IRE1) signalling and ERO1α, as compared with healthy controls. In the mouse model of galactosamine (GaIN)/lipopolysaccharide (LPS)-induced ALF, the hepatocellular injury was accompanied by up-regulated PERK signalling, ATF6 signalling, IRE1 signalling, CHOP and ERO1α. In contrast, CHOP deficiency decreased hepatocellular apoptosis/necrosis and increased animal survival. Furthermore, disruption of CHOP decreased ERO1α expression leading to reducing ROS-induced cell death in vivo and in vitro. Interestingly, ERO1α overexpression restored GaIN/LPS-induced hepatocellular injury in CHOP-deficient mice. Our studies demonstrate for the first time that CHOP promotes liver damage during ALF through activation of ERO1α, a key mediator to link ER stress and ROS. Therefore, targeting CHOP/ERO1α signalling could be a novel therapeutic approach during ALF.

Sterile inflammation in Drosophila

The study of immune responses in Drosophila has already yielded significant results with impacts on our understanding of vertebrate immunity, such as the characterization of the Toll receptor. Several recent papers have focused on the humoral response to damage signals rather than pathogens, particularly damage signals from tumour-like tissues generated by loss of cell polarity or chromosomal instability. Both the triggers that generate this sterile inflammation and the systemic and local effects of it are only just beginning to be characterized in Drosophila. Here we review the molecular mechanisms that are known that give rise to the recruitment of Drosophila phagocytes, called hemocytes, as well as the signals, such as TNFα, that stimulated hemocytes emit at sites of perceived damage. The signalling consequences of inflammation, such as the activation of JNK, and the potential for modifying this response are also discussed.

Reactive oxygen species regulate Smac mimetic/TNFα-induced necroptotic signaling and cell death

Necroptosis represents a key programmed cell death pathway involved in various physiological and pathophysiological conditions. However, the role of reactive oxygen species (ROS) in necroptotic signaling has remained unclear. In the present study, we identify ROS as critical regulators of BV6/tumor necrosis factor-α (TNFα)-induced necroptotic signaling and cell death. We show that BV6/TNFα-induced cell death depends on ROS production, as several ROS scavengers such as butylated hydroxyanisole, N-acetylcysteine, α-tocopherol and ethyl pyruvate significantly rescue cell death. Before cell death, BV6/TNFα-stimulated ROS generation promotes stabilization of the receptor-interacting protein kinase 1 (RIP1)/RIP3 necrosome complex via a potential positive feedback loop, as on the one hand radical scavengers attenuate RIP1/RIP3 necrosome assembly and phosphorylation of mixed lineage kinase domain like (MLKL), but on the other hand silencing of RIP1 or RIP3 reduces ROS production. Although MLKL knockdown effectively decreases BV6/TNFα-induced cell death, it does not affect RIP1/RIP3 interaction and only partly reduces ROS generation. Moreover, the deubiquitinase cylindromatosis (CYLD) promotes BV6/TNFα-induced ROS generation and necrosome assembly even in the presence of BV6, as CYLD silencing attenuates these events. Genetic silencing of phosphoglycerate mutase 5 or dynamin-related protein 1 (Drp1) fails to protect against BV6/TNFα-induced cell death. By demonstrating that ROS are involved in regulating BV6/TNFα-induced necroptotic signaling, our study provides new insights into redox regulation of necroptosis.

Toxicity of metal oxide nanoparticles in Escherichia coli correlates with conduction band and hydration energies

Metal oxide nanoparticles (MOx NPs) are used for a host of applications, such as electronics, cosmetics, construction, and medicine, and as a result, the safety of these materials to humans and the environment is of considerable interest. A prior study of 24 MOx NPs in mammalian cells revealed that some of these materials show hazard potential. Here, we report the growth inhibitory effects of the same series of MOx NPs in the bacterium Escherichia coli and show that toxicity trends observed in E. coli parallel those seen previously in mammalian cells. Of the 24 materials studied, only ZnO, CuO, CoO, Mn2O3, Co3O4, Ni2O3, and Cr2O3 were found to exert significant growth inhibitory effects; these effects were found to relate to membrane damage and oxidative stress responses in minimal trophic media. A correlation of the toxicological data with physicochemical parameters of MOx NPs revealed that the probability of a MOx NP being toxic increases as the hydration enthalpy becomes less negative and as the conduction band energy approaches those of biological molecules. These observations are consistent with prior results observed in mammalian cells, revealing that mechanisms of toxicity of MOx NPs are consistent across two very different taxa. These results suggest that studying nanotoxicity in E. coli may help to predict toxicity patterns in higher organisms.

Folate decorated delivery of self assembled betulinic acid nano fibers: a biocompatible anti-leukemic therapy

The study was aimed to develop folate receptor mediated delivery of self assembled betulinic acid nano fibers to leukemic cells and to investigate their mode of action.

TRAIL-based tumor sensitizing galactoxyloglucan, a novel entity for targeting apoptotic machinery

Tumor necrosis factor-related apoptosis-inducing ligand (TRAIL) is an attractive target for cancer therapy due to its ability to selectively induce apoptosis in cancer cells, without causing significant toxicity in normal tissues. We previously reported that galactoxyloglucan (PST001) possesses significant antitumor and immunomodulatory properties. However, the exact mechanism in mediating this anticancer effect is unknown. This study, for the first time, indicated that PST001 sensitizes non-small cell lung cancer (A549) and nasopharyngeal (KB) cells to TRAIL-mediated apoptosis. In vitro studies suggested that PST001 induced apoptosis primarily via death receptors and predominantly activated caspases belonging to the extrinsic apoptotic cascade. Microarray profiling of PST001 treated A549 and KB cells showed the suppression of survivin (BIRC5) and anti-apoptotic Bcl-2, as well as increased cytochrome C. TaqMan low density array analysis of A549 cells also confirmed that the induction of apoptosis by the polysaccharide occurred through the TRAIL-DR4/DR5 pathways. This was finally confirmed by in silico analysis, which revealed that PST001 binds to TRAIL-DR4/DR5 complexes more strongly than TNF and Fas ligand-receptor complexes. In summary, our results suggest the potential of PST001 to be developed as an anticancer agent that not only preserves innate biological activity of TRAIL, but also sensitizes cancer cells to TRAIL-mediated apoptosis.

Oxidative damage and antioxidative therapy in systemic sclerosis

Systemic sclerosis (SSc) is an autoimmune connective tissue disorder of unknown etiology. This disease is characterized by a large variety of clinical patterns, which include the fibrosis of skin and visceral organs causing a variety of clinical manifestations. Genetic and environmental factors participate in the etiology of this disease; however, recently many studies underline the oxidative background influencing the course and complications of this disease. Reactive oxygen species (ROS) synthesized in SSc can mediate extra- and intracellular oxidative processes affecting endothelial cells and fibroblasts. The estimation of prooxidative markers in the pathogenesis of SSc can enable the identification of useful markers for disease activity and, thus, may help in planning appropriate therapy focusing on the fibrotic or vascular pattern. Recently, many attempts have been made to find antioxidative molecules (nutritional and pharmacological) reducing the prooxidant state in a variety of cells—mainly in endothelium and proliferating fibroblasts. This paper presents both the background of oxidative stress processes in systemic sclerosis mediated by different mechanisms and the evidence suggesting which of the dietary and pharmacological antioxidants can be used as therapeutic targets for this disease.

Vitamin E in sarcopenia: current evidences on its role in prevention and treatment

Sarcopenia is a geriatric syndrome that is characterized by gradual loss of muscle mass and strength with increasing age. Although the underlying mechanism is still unknown, the contribution of increased oxidative stress in advanced age has been recognized as one of the risk factors of sarcopenia. Thus, eliminating reactive oxygen species (ROS) can be a strategy to combat sarcopenia. In this review, we discuss the potential role of vitamin E in the prevention and treatment of sarcopenia. Vitamin E is a lipid soluble vitamin, with potent antioxidant properties and current evidence suggesting a role in the modulation of signaling pathways. Previous studies have shown its possible beneficial effects on aging and age-related diseases. Although there are evidences suggesting an association between vitamin E and muscle health, they are still inconclusive compared to other more extensively studied chronic diseases such as neurodegenerative diseases and cardiovascular diseases. Therefore, we reviewed the role of vitamin E and its potential protective mechanisms on muscle health based on previous and current in vitro and in vivo studies.

Polyunsaturated fatty acids balance affects platelet NOX2 activity in patients with liver cirrhosis

BACKGROUND

NADPH-oxidase-2 up-regulation has been suggested in liver damage perpetuation via an oxidative stress-mediated mechanism. n-6/n-3 polyunsaturated fatty acids ratio derangement has been reported in liver disease.

AIM

To explore polyunsaturated fatty acids balance and its interplay with platelet oxidative stress in liver cirrhosis.

METHODS

A cross-sectional study in 51 cirrhotic patients and sex- and age-matched controls was performed. Serum polyunsaturated fatty acids and oxidative stress markers (urinary isoprostanes and serum soluble NADPH-oxidase-2-derived peptide) were measured. The effect on platelet oxidative stress of n-6/n-3 polyunsaturated fatty acids ratio in vitro and in vivo (1-week supplementation with 3g/daily n-3-polyunsaturated fatty acids) was tested.

RESULTS

Compared to controls, cirrhotic patients had significantly higher n-6/n-3 polyunsaturated fatty acids ratio. n-6/n-3 polyunsaturated fatty acids ratio correlated significantly with disease severity and oxidative stress markers. In vitro experiments showed that in Child-Pugh C patients' platelets incubation with low n-6/n-3 polyunsaturated fatty acids ratio resulted in dose-dependent decrease of radical oxigen species (-39%), isoprostanes (-25%) and NADPH-oxidase-2 regulation (-51%). n-3 polyunsaturated fatty acids supplemented patients showed significant oxidative stress indexes reduction.

CONCLUSIONS

In cirrhosis, n-6/n-3 polyunsaturated fatty acids imbalance up-regulates platelet NADPH-oxidase-2 with ensuing oxidative stress. Further study to evaluate if n-3 supplementation may reduce disease progression is warranted.

Rho GTPases, oxidation, and cell redox control

While numerous studies support regulation of Ras GTPases by reactive oxygen and nitrogen species, the Rho subfamily has received considerably less attention. Over the last few years, increasing evidence is emerging that supports the redox sensitivity of Rho GTPases. Moreover, as Rho GTPases regulate the cellular redox state by controlling enzymes that generate and convert reactive oxygen and nitrogen species, redox feedback loops likely exist. Here, we provide an overview of cellular oxidants, Rho GTPases, and their inter-dependence.

The impact of salsalate treatment on serum levels of advanced glycation end products in type 2 diabetes

OBJECTIVE Salsalate is a nonacetylated salicylate that lowers glucose levels in people with type 2 diabetes (T2D). Here we examined whether salsalate also lowered serum-protein-bound levels of early and advanced glycation end products (AGEs) that have been implicated in diabetic vascular complications. RESEARCH DESIGN AND METHODS Participants were from the Targeting Inflammation Using Salsalate for Type 2 Diabetes (TINSAL-T2D) study, which examined the impact of salsalate treatment on hemoglobin A1c (HbA1c) and a wide variety of other parameters. One hundred eighteen participants received salsalate, 3.5 g/day for 48 weeks, and 109 received placebo. Early glycation product levels (HbA1c and fructoselysine [measured as furosine]) and AGE levels (glyoxal and methylglyoxal hydroimidazolones [G-(1)H, MG-(1)H], carboxymethyllysine [CML], carboxyethyllysine [CEL], pentosidine) were measured in patient serum samples. RESULTS Forty-eight weeks of salsalate treatment lowered levels of HbA1c and serum furosine (P < 0.001) and CML compared with placebo. The AGEs CEL and G-(1)H and MG-(1)H levels were unchanged, whereas pentosidine levels increased more than twofold (P < 0.001). Among salsalate users, increases in adiponectin levels were associated with lower HbA1c levels during follow-up (P < 0.001). Changes in renal and inflammation factor levels were not associated with changes in levels of early or late glycation factors. Pentosidine level changes were unrelated to changes in levels of renal function, inflammation, or cytokines. CONCLUSIONS Salsalate therapy was associated with a reduction in early but not late glycation end products. There was a paradoxical increase in serum pentosidine levels suggestive of an increase in oxidative stress or decreased clearance of pentosidine precursor.

Nox1 causes ileocolitis in mice deficient in glutathione peroxidase-1 and -2

We previously reported that mice deficient in two Se-dependent glutathione peroxidases, GPx1 and GPx2, have spontaneous ileocolitis. Disease severity depends on mouse genetic background. Whereas C57BL/6J (B6) GPx1/2-double-knockout (DKO) mice have moderate ileitis and mild colitis, 129S1Svlm/J (129) DKO mice have severe ileocolitis. Because GPx's are antioxidant enzymes, we hypothesized that elevated reactive oxygen species trigger inflammation in these DKO mice. To test whether NADPH oxidase 1 (Nox1) contributes to colitis, we generated B6 triple-KO (TKO) mice to study their phenotype. Because the Nox1 gene is X-linked, we analyzed the effects of Nox1 on male B6 TKO mice and female B6 DKO mice with the Nox1(+/-) (het-TKO) genotype. We found that the male TKO and female het-TKO mice are virtually disease-free when monitored from 8 through 50 days of age. Male TKO and female het-TKO mice have nearly no signs of disease (e.g., lethargy and perianal alopecia) that are often exhibited in the DKO mice; further, the slower growth rate of DKO mice is almost completely eliminated in male TKO and female het-TKO mice. Male TKO and female het-TKO mice no longer have the shortened small intestine present in the DKO mice. Finally, the pathological characteristics of the DKO ileum, including the high level of crypt apoptosis (analyzed by apoptotic figures, TUNEL, and cleaved caspase-3 immunohistochemical staining), high numbers of Ki-67-positive crypt epithelium cells, and elevated levels of monocytes expressing myeloperoxidase, are all significantly decreased in male TKO mice. The attenuated ileal and colonic pathology is also evident in female het-DKO mice. Furthermore, the male DKO ileum has eightfold higher TNF cytokine levels than TKO ileum. Nox1 mRNA is highly elevated in both B6 and 129 DKO ileum compared to wild-type mouse ileum. Taking these results together, we propose that ileocolitis in the DKO mice is caused by Nox1, which is induced by TNF. The milder disease in female het-TKO intestine is probably due to random or imprinted X-chromosome inactivation, which produces mosaic Nox1 expression.

Prediabetes: grounds of pitfall signalling alteration for cardiovascular disease

Prediabetes manifested by impaired glucose tolerance and impaired fasting glucose offers high risk of myocardial dysfunction by causing endothelial dysfunction, inflammation, oxidative stress, atherosclerosis and genetic alterations.

Loss of STAT3 in mouse embryonic fibroblasts reveals its Janus-like actions on mitochondrial function and cell viability

STAT3 has been implicated in mitochondrial function; however, the physiological relevance of this action is not established. Here we studied the importance of STAT3 to the cellular response to stimuli, TNFα and serum deprivation, which increase mitochondrial reactive oxygen species (ROS) formation. Experiments were performed using wild type (WT) and STAT3 knockout (KO) mouse embryonic fibroblasts (MEF). Both WT and STAT3 KO MEF expressed similar levels of tumor necrosis factor receptor 1 (TNFR1) and exhibited comparable IκBα degradation with TNFα. However, in the absence of STAT3 nuclear accumulation of NFκB p65 with TNFα was attenuated and induction of the survival protein c-FLIPL was eliminated. Nonetheless, WT MEF were more sensitive to TNFα-induced death which was attributed to necrosis. Deletion of STAT3 decreased ROS formation induced by TNFα and serum deprivation. STAT3 deletion was associated with lower levels of complex I and rates of respiration. Relative to WT cells, mitochondria of STAT3 KO cells released significantly more cytochrome c in response to oxidative stress and had greater caspase 3 cleavage due to serum deprivation. Our findings are consistent with STAT3 being important for mitochondrial function and cell viability by ensuring mitochondrial integrity and the expression of pro-survival genes.

GABA tea prevents cardiac fibrosis by attenuating TNF-alpha and Fas/FasL-mediated apoptosis in streptozotocin-induced diabetic rats

GABA tea is a tea product that contains a high level of gamma-aminobutyric acid (GABA). This study investigated the effects of GABA tea on the heart in a diabetic rat model. Male Wistar rats were injected with 55mg/kg streptozotocin (STZ) to induce diabetes for 2weeks and then orally given dosages of 4.55 and 45.5mg/kg/day GABA tea extract for 6weeks. The results revealed that fasting blood glucose levels returned to normal levels in GABA tea-treated diabetic rats, but not in the untreated diabetic rats. Additionally, GABA tea effectively inhibited cardiac fibrosis induced by STZ. Further experiments showed that the STZ-induced protein levels of tumor necrosis factor-alpha (TNF-alpha), Fas, activated caspase-8 and caspase-3 were significantly inhibited by the GABA tea treatment. Therefore, our data suggest that the inhibiting effect of GABA tea on STZ-induced cardiac fibrosis in diabetic rats may be mediated by reducing blood glucose and further attenuating TNF-alpha expression and/or Fas/Fas ligand (FasL)-mediated apoptosis. These findings will provide implications for the potential anti-diabetic properties of GABA tea.

The role of TNF-α and TNF superfamily members in the pathogenesis of calcific aortic valvular disease

Calcific aortic valve disease (CAVD) represents a slowly progressive pathologic process associated with major morbidity and mortality. The process is characterized by multiple steps: inflammation, fibrosis, and calcification. Numerous studies focalized on its physiopathology highlighting different "actors" for the multiple "acts." This paper focuses on the role of the tumor necrosis factor superfamily (TNFSF) members in the pathogenesis of CAVD. In particular, we discuss the clinical and experimental studies providing evidence of the involvement of tumor necrosis factor-alpha (TNF-α), receptor activator of nuclear factor-kappa B (NF-κB) ligand (RANKL), its membrane receptor RANK and its decoy receptor osteoprotegerin (OPG), and TNF-related apoptosis-inducing ligand (TRAIL) in valvular calcification.

Molecular biology of atherosclerosis

At least 468 individual genes have been manipulated by molecular methods to study their effects on the initiation, promotion, and progression of atherosclerosis. Most clinicians and many investigators, even in related disciplines, find many of these genes and the related pathways entirely foreign. Medical schools generally do not attempt to incorporate the relevant molecular biology into their curriculum. A number of key signaling pathways are highly relevant to atherogenesis and are presented to provide a context for the gene manipulations summarized herein. The pathways include the following: the insulin receptor (and other receptor tyrosine kinases); Ras and MAPK activation; TNF-α and related family members leading to activation of NF-κB; effects of reactive oxygen species (ROS) on signaling; endothelial adaptations to flow including G protein-coupled receptor (GPCR) and integrin-related signaling; activation of endothelial and other cells by modified lipoproteins; purinergic signaling; control of leukocyte adhesion to endothelium, migration, and further activation; foam cell formation; and macrophage and vascular smooth muscle cell signaling related to proliferation, efferocytosis, and apoptosis. This review is intended primarily as an introduction to these key signaling pathways. They have become the focus of modern atherosclerosis research and will undoubtedly provide a rich resource for future innovation toward intervention and prevention of the number one cause of death in the modern world.