Effect of Dark Chocolate Extracts on Phorbol 12-Myristate 13-Acetate-Induced Oxidative Burst in Leukocytes Isolated by Normo-Weight and Overweight/Obese Subjects.

Oxidative and inflammatory stress represents a major risk factor for cardiovascular disease (CVD) in overweight and obese subjects. Between the different plant foods, chocolate has been shown to decrease CVD risk due to its antioxidant and anti-inflammatory properties. However, as we recently showed in epidemiological studies, meta-analyses, and human trials, dietary antioxidants resulted more effective in subjects characterized by an ongoing oxidative stress, than in healthy people. Aim of this work was to investigate the effect of different concentrations of chocolate phenolic extract (CPE) on in vitro free radical production, stimulated by phorbol 12-myristate 13-acetate (PMA), in leukocytes extracted from blood of normo-weight and overweight/obese subjects. Neutrophils from overweight/obese group had a significantly higher free radical production compared to the normo-weight group. In neutrophils, the lowest CPE concentration significantly reduced free radical production in overweight/obese group only, and higher CPE concentrations were effective in both groups. In monocytes, the CPE concentration that was significantly effective in reducing free radical production was lower in overweight/obese subjects than in normo-weight subjects. Chocolate polyphenol extracts inhibit oxidative burst in human neutrophils and monocytes with a higher efficiency in subjects characterized by an unphysiological oxidative/inflammatory stress, such as overweight and obese. Results of this study provide further evidence about a differential role of dietary antioxidant strictly related to the "stress" condition of the subjects.

Flavonoids and immune function in human: a systematic review.

Flavonoids, through a modulation of immune function, have been suggested to be involved in the role played by plant foods in disease prevention. We performed a systematic search in the MEDLINE database to review the effect of flavonoid-rich foods and flavonoids supplements on immune function. A total of 58 studies, were identified as suitable: 41 addressed in vivo proinflammatory cytokines and 15 measured ex vivo markers of immune function. According to our findings and on the basis of single food items, the number of studies in humans is limited and, for galenic supplements, only quercetin has been investigated. More evidences are needed to clarify the role of flavonoids as modulator of immune function in humans.

Oxidative stress in atherosclerosis development: the central role of LDL and oxidative burst.

The involvement of both oxidative stress and hyperlipaemia in atherosclerosis development is well established. Oxidative burst is an innate immune response to infection, the latter being associated also with marked changes in lipid and lipoprotein metabolism, aimed to neutralize endotoxin toxic effects. On the other hand, lipid overload may increase lipopolysaccharide circulating levels and oxidative stress. Whilst these changes may be beneficial from the perspective of host defense, if they become chronic, they likely increase the risk of atherosclerosis. In particular, oxidation of lipoproteins, resulting from an imbalance of the pro- and antioxidant equilibrium, is involved in the pathologic process of atherosclerosis, changing cellular functions. Lipid oxidation, induced by leukocytes derived reactive oxygen species, can amplify foam cell formation through oxidized low density lipoproteins LDL (oxLDL) formation and uptake. The main enzymes, operating during oxidative burst, involved in LDL oxidation are NADPH oxidase and myeloperoxidase. In vitro studies have shown that oxLDL are able to induce many proatherogenic processes, including modulation of oxidative burst. OxLDL may also induce maturation of dendritic cells and regulate the shift from classical (M1) to alternative (M2) macrophage activation and from T helper 1 to T helper 2 response, suggesting that these could act as a bridge between innate and adaptative immunity, both involved in plaque development. Understanding the relationship between oxLDL and leukocyte oxidative burst helps to explain the involvement of innate immune responses in the early phases of atherosclerosis. The present review focuses on this interplay.