Fathi Driss

NAD(P)H oxidase Nox-4 mediates 7-ketocholesterol-induced endoplasmic reticulum stress and apoptosis in human aortic smooth muscle cells

ABSTRACT The mechanisms involved in the cytotoxic action of oxysterols in the pathogenesis of atherosclerosis still remain poorly understood. Among the major oxysterols present in oxidized low-density lipoprotein, we show here that 7-ketocholesterol (7-Kchol) induces oxidative stress and/or apoptotic events in human aortic smooth muscle cells (SMCs). This specific effect of 7-Kchol is mediated by a robust upregulation (threefold from the basal level) of Nox-4, a reactive oxygen species (ROS)-generating NAD(P)H oxidase homologue. This effect was highlighted by silencing Nox-4 expression with a specific small interfering RNA, which significantly reduced the 7-Kchol-induced production of ROS and abolished apoptotic events. Furthermore, the 7-Kchol activating pathway included an early triggering of endoplasmic reticulum stress, as assessed by transient intracellular Ca2+ oscillations, and the induction of the expression of the cell death effector CHOP and of GRP78/Bip chaperone via the activation of IRE-1, all hallmarks of the unfolded protein response (UPR). We also showed that 7-Kchol activated the IRE-1/Jun-NH2-terminal kinase (JNK)/AP-1 signaling pathway to promote Nox-4 expression. Silencing of IRE-1 and JNK inhibition downregulated Nox-4 expression and subsequently prevented the UPR-dependent cell death induced by 7-Kchol. These findings demonstrate that Nox-4 plays a key role in 7-Kchol-induced SMC death, which is consistent with the hypothesis that Nox-4/oxysterols are involved in the pathogenesis of atherosclerosis.

Punicic Acid a Conjugated Linolenic Acid Inhibits TNFα-Induced Neutrophil Hyperactivation and Protects from Experimental Colon Inflammation in Rats

Background Neutrophils play a major role in inflammation by releasing large amounts of ROS produced by NADPH-oxidase and myeloperoxidase (MPO). The proinflammatory cytokine TNFα primes ROS production through phosphorylation of the NADPH-oxidase subunit p47phox on Ser345. Conventional anti-inflammatory therapies remain partially successful and may have side effects. Therefore, regulation of neutrophil activation by natural dietary components represents an alternative therapeutic strategy in inflammatory diseases such as inflammatory bowel diseases. The aim of this study was to assess the effect of punicic acid, a conjugated linolenic fatty acid from pomegranate seed oil on TNFα-induced neutrophil hyperactivation in vitro and on colon inflammation in vivo. Methodology and Principal Findings We analyzed the effect of punicic acid on TNFα-induced neutrophil upregulation of ROS production in vitro and on TNBS-induced rat colon inflammation. Results show that punicic acid inhibited TNFα-induced priming of ROS production in vitro while preserving formyl-methionyl-leucyl-phenylalanine (fMLP)-induced response. This effect was mediated by the inhibition of Ser345-p47phox phosphorylation and upstream kinase p38MAPK. Punicic acid also inhibited fMLP- and TNFα+fMLP-induced MPO extracellular release from neutrophils. In vivo experiments showed that punicic acid and pomegranate seed oil intake decreased neutrophil-activation and ROS/MPO-mediated tissue damage as measured by F2-isoprostane release and protected rats from TNBS-induced colon inflammation. Conclusions/Significance These data show that punicic acid exerts a potent anti-inflammatory effect through inhibition of TNFα-induced priming of NADPH oxidase by targeting the p38MAPKinase/Ser345-p47phox-axis and MPO release. This natural dietary compound may provide a novel alternative therapeutic strategy in inflammatory diseases such as inflammatory bowel diseases.

Diagnostic accuracy of serum hepcidin for iron deficiency in critically ill patients with anemia.

PurposeInflammation-induced anemia is frequent among critically ill patients and can be aggravated by true iron deficiency (ID) resulting from blood losses. The serum hepcidin level controls the availability of iron for erythropoiesis, and its determination offers new perspectives for the diagnosis of ID in the presence of inflammation. We conducted a prospective observational study to determine the cutoff value and diagnostic accuracy of hepcidin levels for detecting ID in critically ill anemic patients.MethodsPatients suffering from anemia (hemoglobin <100xa0g/l) and expected to stay for more than 7xa0days in intensive care had weekly determinations of hematological and iron parameters, including hepcidin levels (ELISA test). The iron status for each set of measures was determined by the consensus of three experts, blinded to hepcidin values.ResultsOf 51 patients (36 male/15 female), 5 had ID at inclusion, while 8 developed ID during their stay. A total of 128 iron profiles were analyzed. Median hepcidin levels were 80.5 (0.05–548.3) and 526.6 (246.7–891.4)xa0µg/l for ID and non-ID profiles, respectively. The onset of ID during the ICU stay led to a progressive decline in hepcidin levels, whereas a persistent inflammatory profile remained associated with high hepcidin concentrations. The optimal threshold for serum hepcidin for ID diagnosis was assessed by building 100 ROC curves using a resampling method and found at 129.5xa0µg/l [95% CIxa0=xa0(115.5–143.4)].ConclusionsHepcidin levels may be suppressed by ID even in case of inflammation. Serum hepcidin of 129.5xa0µg/l was the most accurate threshold for ID diagnosis in critically ill patients with anemia.

Protectin DX, a Double Lipoxygenase Product of DHA, Inhibits Both ROS Production in Human Neutrophils and Cyclooxygenase Activities

Neutrophils play a major role in inflammation by releasing large amounts of reactive oxygen species (ROS) produced by NADPH oxidase (NOX) and myeloperoxidase (MPO). This ROS overproduction is mediated by phosphorylation of the NOX subunits in an uncontrolled manner. Therefore, targeting neutrophil subunits would represent a promising strategy to moderate NOX activity, lower ROS, and other inflammatory agents, such as cytokines and leukotrienes, produced by neutrophils. For this purpose, we investigated the effects of protectin DX (PDX)—a docosahexaenoic acid di-hydroxylated product which inhibits blood platelet aggregation—on neutrophil activation in vitro. We found that PDX decreases ROS production, inhibits NOX activation and MPO release from neutrophils. We also confirm, that PDX is an anti-aggregatory and anti-inflammatory agent by inhibiting both cyclooxygenase-1 and -2 (COX-1 and COX-2, E.C. 1.14.99.1) as well as COX-2 in lipopolysaccharides-treated human neutrophils. However, PDX has no effect on the 5-lipoxygenase pathway that produces the chemotactic agent leukotriene B4 (LTB4). Taken together, our results suggest that PDX could be a protective agent against neutrophil invasion in chronic inflammatory diseases.

Docosahexaenoic acid, protectin synthesis: relevance against atherothrombogenesis.

DHA is an abundant nutrient from marine lipids: its specific biological effects have been investigated in human volunteers, taking into consideration the dose effects. We report herein that, at dosages below 1 g/d, DHA proved to be effective in lowering blood platelet function and exhibited an antioxidant effect. However, this was no longer the case following 1.6 g/d, showing then a U-shape response. The antioxidant effect has been observed in platelets as well as LDL, of which the redox status is assumed to be crucial in their relationship with atherosclerosis. Second, the oxygenated products of DHA, especially protectins produced by lipoxygenases, have been considered for their potential to affect blood platelets and leucocytes. It is concluded that DHA is an interesting nutrient to reduce atherothrombogenesis, possibly through complementary mechanisms involving lipoxygenase products of DHA.

Antioxidant Effect of Hydroxytyrosol, a Polyphenol from Olive Oil by Scavenging Reactive Oxygen Species Produced by Human Neutrophils

Publisher Summary The beneficial effects of the Mediterranean diet on human health, particularly in the prevention of cardiovascular diseases, inflammatory diseases, and some cancers, is widely recognized. This diet is characterized by a high intake of virgin olive oil, which is rich in phenolic products, which have a strong antioxidant activity. Hydroxytyrosol, the most active olive oil polyphenol scavenges reactive oxygen species (ROS) produced by neutrophils and other phagocytes, which are involved in induction of many diseases. In addition to hydroxytyrosol, other olive oil compounds such as oleuropein, tyrosol, squalene, oleic acid, and tocopherols also have antioxidant activities. The beneficial effect of antioxidant uptake on health is well demonstrated. Dietary intake of olive oil polyphenols may lower the risk of ROS-mediated diseases and explain the beneficial effect of the Mediterranean diet on human health.

Hospital Diet Enriched With Rapeseed or Sunflower Oils Is Associated With a Decrease in Plasma 16:1n-7 and Some Metabolic Disorders in the Elderly

We recently demonstrated that the prevalence of dysglycemia was high among hospitalized elderly people who were fed a low fat diet (27.7% of energy) and was positively associated with plasma 16:1n-7, an indicator of de novo lipogenesis (DNL). Fatty acids in the DNL pathway have been shown to be associated with a higher risk of metabolic syndrome (MetS). The purpose of this study was to investigate the potential beneficial effects of fat enrichment (up to 34.1%en) of the hospital diet in 111 patients (30 men and 81 women, 84 ± 7 years) during 6 weeks. Based on gender, they were randomly given a diet supplemented either with rapeseed oil (RO) or with sunflower oil (SO). Fatty acids of cholesteryl esters and erythrocyte phospholipids and markers of metabolic disorders were evaluated before and after dietary intervention. Both enriched diets significantly, and to a similar extent, decreased (1) the overall prevalence of dysglycemia (by 25-33%) and MetS (by 31-43%) and (2) plasma 16:1n-7 mol% in men and women. Dysglycemia prevalence adjusted by the diets was reduced in men versus baseline; no change was found in women. Enrichment of the diet with RO or SO resulted in a difference in fatty acid compositions, that is, EPA (mol%) and the omega-3 index increased with RO, while proportions of 18:1n-7, 18:1n-9, and EPA decreased with SO. These findings highlight the need for adequate fat intake in the elderly. For supplementation of the hospital diet, RO, which led to a higher proportion of circulating n-3 polyunsaturated fatty acids (PUFA) and is known to be beneficial, may be preferred to SO.