Update on Anti-Inflammatory Molecular Mechanisms Induced by Oleic Acid.

In 2010, the Mediterranean diet was recognized by UNESCO as an Intangible Cultural Heritage of Humanity. Olive oil is the most characteristic food of this diet due to its high nutraceutical value. The positive effects of olive oil have often been attributed to its minor components; however, its oleic acid (OA) content (70-80%) is responsible for its many health properties.

Curcumin enhances LXRα in an AMP-activated protein kinase-dependent manner in human macrophages.

Liver X receptor alpha (LXRα) is a nuclear receptor involved in cholesterol homeostasis. Curcumin, a traditional Chinese derivative from the rhizomes of Curcuma longa and a well-known AMP-activated protein kinase (AMPK) activator, possess hypocholesterolemic activity, however, the possible link between AMPK and cholesterol is unknown. In this study, we have investigated whether curcumin regulates metabolic changes in cholesterol metabolism via LXRα in THP-1 human macrophages, the cells implicated in atheroma plaques formation.

Grapefruit Flavonoid Naringenin Regulates the Expression of LXRα in THP-1 Macrophages by Modulating AMP-Activated Protein Kinase.

The present work investigates the modulation of grapefruit flavonoid naringenin over liver X receptor alpha (LXRα) and its target genes in THP-1 macrophages, focusing on AMP-activated protein kinase (AMPK) implication. Naringenin induced LXRα at mRNA and protein levels besides influencing the expression of LXRα target genes ABCA1, ABCG1 (ATP-binding cassette A1 and G1), and SREBP1c (sterol response element binding protein 1c) in THP-1 macrophages. The increased LXRα mRNA and protein expression was reverted when AMPK was inhibited by its chemical inhibitor, compound C or by transfection with AMPK α1 and α2 siRNA.

Platelet-activating factor and hydrogen peroxide exert a dual modulatory effect on the transcription of LXRα and its target genes in human neutrophils.

Liver X receptors (LXRs) are ligand-activated nuclear receptors involved mainly in the regulation of cholesterol metabolism in many organs, including liver and intestine, as well as in macrophages and neutrophils. Besides, both anti-inflammatory and pro-inflammatory properties have been ascribed to LXRs. The effect of the inflammatory condition on the expression of LXRα and its target genes has not been previously addressed in human neutrophils.

7-Keto-cholesterol and 25-hydroxy-1 cholesterol rapidly enhance ROS production in human neutrophils.

Purpose: Oxysterols are cholesterol-oxygenated derivatives generated in the organism and also present in foods because of cholesterol oxidation during processing and storage. They are the natural ligands of liver X receptors (LXRs) and are generally recognized as hypocholesterolemic and anti-inflammatory molecules although this latter property is still controversial. Most oxysterol studies have been performed in macrophages, whereas the effects of oxysterols in neutrophils are poorly known.

Oleic acid modulates mRNA expression of liver X receptor (LXR) and its target genes ABCA1 and SREBP1c in human neutrophils.

Purpose: Regulation of liver X receptors (LXRs) is essential for cholesterol homeostasis and inflammation. The present study was conducted to determine whether oleic acid (OA) could regulate mRNA expression of LXRα and LXRα-regulated genes and to assess the potential promotion of oxidative stress by OA in neutrophils.

Methods: Human neutrophils were treated with OA at different doses and LXR target gene expression, oxidative stress production, lipid efflux and inflammation state were analyzed.

Platelet-activating factor downregulates the expression of liver X receptor-α and its target genes in human neutrophils.

Liver X receptors (LXRs) are ligand-activated members of the nuclear receptor superfamily that regulate the expression of genes involved in lipid metabolism and inflammation, although their role in inflammation and immunity is less well known. It has been reported that oxysterols/LXRs may act as anti-inflammatory molecules, although opposite actions have also been reported. In this study, we investigated the effect of platelet-activating factor (PAF), a proinflammatory molecule, on LXRα signalling in human neutrophils.

Calcineurin expression and activity is regulated by the intracellular redox status and under hypertension in human neutrophils.

Calcineurin (protein phosphatase 2B) (CN) comprises a family of serine/threonine phosphatases that play a pivotal role in signal transduction cascades in a variety of cells, including neutrophils. Angiotensin II (Ang II) increases both activity and de novo synthesis of CN in human neutrophils. This study focuses on the role that intracellular redox status plays in the induction of CN activity by Ang II.