Influence of apple polyphenols on inflammatory gene expression

Apple flavonoid phloretin inhibits Escherichia coli O157:H7 biofilm formation and ameliorates colon inflammation in rats

Pathogenic biofilms have been associated with persistent infections due to their high resistance to antimicrobial agents, while commensal biofilms often fortify the host's immune system. Hence, controlling biofilm formation of both pathogenic bacteria and commensal bacteria is important in bacterium-related diseases. We investigated the effect of plant flavonoids on biofilm formation of enterohemorrhagic Escherichia coli O157:H7. The antioxidant phloretin, which is abundant in apples, markedly reduced E. coli O157:H7 biofilm formation without affecting the growth of planktonic cells, while phloretin did not harm commensal E. coli K-12 biofilms. Also, phloretin reduced E. coli O157:H7 attachment to human colon epithelial cells. Global transcriptome analyses revealed that phloretin repressed toxin genes (hlyE and stx(2)), autoinducer-2 importer genes (lsrACDBF), curli genes (csgA and csgB), and dozens of prophage genes in E. coli O157:H7 biofilm cells. Electron microscopy confirmed that phloretin reduced fimbria production in E. coli O157:H7. Also, phloretin suppressed the tumor necrosis factor alpha-induced inflammatory response in vitro using human colonic epithelial cells. Moreover, in the rat model of colitis induced by trinitrobenzene sulfonic acid (TNBS), phloretin significantly ameliorated colon inflammation and body weight loss. Taken together, our results suggest that the antioxidant phloretin also acts as an inhibitor of E. coli O157:H7 biofilm formation as well as an anti-inflammatory agent in inflammatory bowel diseases without harming beneficial commensal E. coli biofilms.

Effect of ascorbic acid-rich diet on in vivo-induced oxidative stress

Using hyperbaric oxygen (HBO) therapy as an in vivo oxidation model, we investigated the effect of a diet enriched in ascorbic acid (AA) on HBO-induced oxidative stress. Volunteers (n 46) were allocated to the AA-rich diet group or the control group. Blood samples were collected at the basal time, after the 1-week diet before and immediately after the HBO treatment, and 1 week after the HBO treatment. AA level, total antioxidant status (TAS), hydroperoxides (HP), lymphocyte DNA oxidation and DNA repair capacity were assessed. The expression of genes involved in oxidative stress was evaluated in lymphocytes and the protein activity of the modulated genes was determined in the plasma. The AA level and the antioxidant status of plasma were increased by AA-rich food consumption. HBO exposure did not affect the AA levels or TAS, but induced HP formation in the control group. The lymphocytes isolated from dietary-supplemented subjects were resistant to ex vivo DNA oxidation, showing an increased DNA repair capacity compared with controls. A difference in gene expression pattern was observed between the groups. AA-rich foods provide dual protection against oxidative stress, enhancing plasma antioxidant levels and stimulating genes involved in cell detoxification.

Ganodermycin, a novel inhibitor of CXCL10 expression from Ganoderma applanatum

CXCL10 (inducible protein-10) is a highly inducible chemoattractant, which contributes to the recruitment of inflammatory cells, such as macrophages and T-lymphocytes, and thereby has important roles in chronic inflammatory conditions. In a search for new inhibitors of CXCL10 expression in MonoMac6 cells, a novel compound, designated as Ganodermycin, was isolated from fermentations of the basidiomycete Ganoderma applanatum. The structure was determined by a combination of spectroscopic techniques. Ganodermycin inhibited the lipopolysaccharide (LPS)/interferon (IFN)-γ-induced CXCL10 promoter activity in transiently transfected MonoMac6 cells in a dose-dependent manner with IC(50) values of 15-20 μg ml(-1) (53-71 μM). Ganodermycin also reduced LPS/IFN-γ-induced CXCL10 protein synthesis and excretion.

Glycyrrhizic acid and 18β-glycyrrhetinic acid modulate lipopolysaccharide-induced inflammatory response by suppression of NF-κB through PI3K p110δ and p110γ inhibitions

The roots and rhizomes of licorice ( Glycyrrhia ) species have been used extensively as natural sweeteners and herbal medicines. The aim of this work was to determine the in vitro anti-inflammatory effects of glycyrrhizic acid (GA) and 18β-glycyrrhetinic acid (18βGA) from licorice in a lipopolysaccharide (LPS)-stimulated macrophage model. The results showed that treatment with 25-75 μM GA or 18βGA did not reduce RAW 264.7 cell viability but did significantly inhibit the production of LPS-induced nitric oxide (NO), prostaglandin E(2) (PGE(2)), and intracellular reactive oxygen species (ROS). Western blotting and reverse transcriptase polymerase chain reaction (RT-PCR) analyses revealed that GA and 18βGA significantly reduced the protein and mRNA levels of iNOS and COX-2 in LPS-induced macrophages. Both GA and 18βGA inhibited the activation of NF-κB and the activities of phosphoinositide-3-kinase (PI3K) p110δ and p110γ isoforms and then reduced the production of LPS-induced tumor necrosis factor-α (TNF-α), interleukin (IL)-6, and IL-1β in a dose-dependent manner. In conclusion, these results indicate that GA and 18βGA may provide an anti-inflammatory effect by attenuating the generation of excessive NO, PGE(2), and ROS and by suppressing the expression of pro-inflammatory genes through the inhibition of NF-κB and PI3K activity. Thus, the results suggest that GA and 18βGA might serve as potential agents for the treatment of inflammatory-mediated diseases.

Polymeric proanthocyanidins from Sicilian pistachio (Pistacia vera L.) nut extract inhibit lipopolysaccharide-induced inflammatory response in RAW 264.7 cells

BACKGROUND

Positive effects of pistachio nut consumption on plasma inflammatory biomarkers have been described; however, little is known about molecular events associated with these effects.

PURPOSE

We studied the anti-inflammatory activity of a hydrophilic extract from Sicilian Pistacia L. (HPE) in a macrophage model and investigated bioactive components relevant to the observed effects.

METHODS

HPE oligomer/polymer proanthocyanidin fractions were isolated by adsorbance chromatography, and components quantified as anthocyanidins after acidic hydrolysis. Isoflavones were measured by gradient elution HPLC analysis. RAW 264.7 murine macrophages were pre-incubated with either HPE (1- to 20-mg fresh nut equivalents) or its isolated components for 1 h, then washed before stimulating with lipopolysaccharide (LPS) for 24 h. Cell viability and parameters associated with Nuclear Factor-κB (NF-κB) activation were assayed according to established methods including ELISA, Western blot, or cytofluorimetric analysis.

RESULTS

HPE suppressed nitric oxide (NO) and tumor necrosis factor-α (TNF-α) production and inducible NO-synthase levels dose dependently, whereas inhibited prostaglandin E2 (PGE2) release and decreased cyclo-oxygenase-2 content, the lower the HPE amount the higher the effect. Cytotoxic effects were not observed. HPE also caused a dose-dependent decrease in intracellular reactive oxygen species and interfered with the NF-κB activation. Polymeric proanthocyanidins, but not isoflavones, at a concentration comparable with their content in HPE, inhibited NO, PGE2, and TNF-α formation, as well as activation of IκB-α. Oligomeric proanthocyanidins showed only minor effects.

CONCLUSIONS

Our results provide molecular evidence of anti-inflammatory activity of pistachio nut and indicate polymeric proanthocyanidins as the bioactive components. The mechanism may involve the redox-sensitive transcription factor NF-κB. Potential effects associated with pistachio nut consumption are discussed in terms of the proanthocyanidin bioavailability.

Apple polyphenols require T cells to ameliorate dextran sulfate sodium-induced colitis and dampen proinflammatory cytokine expression

Human IBD, including UC and Crohn's disease, is characterized by a chronic, relapsing, and remitting condition that exhibits various features of immunological inflammation and affects at least one/1000 people in Western countries. Polyphenol extracts from a variety of plants have been shown to have immunomodulatory and anti-inflammatory effects. In this study, treatment with APP was investigated to ameliorate chemically induced colitis. Oral but not peritoneal administration of APP during colitis induction significantly protected C57BL/6 mice against disease, as evidenced by the lack of weight loss, colonic inflammation, and shortening of the colon. APP administration dampened the mRNA expression of IL-1β, TNF-α, IL-6, IL-17, IL-22, CXCL9, CXCL10, CXCL11, and IFN-γ in the colons of mice with colitis. APP-mediated protection requires T cells, as protection was abated in Rag-1(-/-) or TCRα(-/-) mice but not in IL-10(-/-), IRF-1(-/-), μMT, or TCRδ(-/-) mice. Administration of APP during colitis to TCRα(-/-) mice actually enhanced proinflammatory cytokine expression, further demonstrating a requirement for TCRαβ cells in APP-mediated protection. APP treatment also inhibited CXCR3 expression by TCRαβ cells, but not B or NK cells, in the colons of mice with colitis; however, depletion of CD4(+) or CD8(+) T cells alone did not abolish APP-mediated protection. Collectively, these results show that oral administration of APP protects against experimental colitis and diminishes proinflammatory cytokine expression via T cells.

Protective effect of apple polyphenols against stress-provoked influenza viral infection in restraint mice

This study was conducted to investigate the effects of apple polyphenol extract (APE) against influenza virus in mice loaded with restraint stress. The high-performance liquid chromatography (HPLC) fingerprint of APE was recorded, and the percentage composition of polyphenols was determined as 81.7%. Our results showed that restraint stress significantly promoted the mortality and duration of complications of mice infected with the H1N1 virus. However, oral administration of APE (100 and 200 mg/kg) improved the survival rates and prolonged living time of stressed mice infected with influenza virus in a dose-dependent manner. APE was further found to significantly improve the number of immunocytes, ratio of CD4 helper cells, secretion of IL-2, and capabilities of natural killer (NK) cytotoxicity (LU10/spleen) in spleens of restraint-stressed mice. In addition, APE also significantly decreased the level of lipid peroxidation and increased oxygen radical absorbance capacity (ORAC) in splenocytes. These results indicated that the protective effects of APE on mice infected with influenza virus were related to the alleviation of stress-induced impairment of immune functions and its antioxidant property might contribute to the immune recovery.

Digestibility of β-lactoglobulin following cross-linking by trametes versicolor laccase and apple polyphenols

?-Lactoglobulin (BLG) is an important nutrient of dairy products and an important allergen in cow?s milk allergy. The aim of this study was to investigate the potential of laccase to cross-link BLG in the presence of an apple phenolic extract (APE) and to characterize the obtained products for their digestibility by pepsin and pancreatin. The composition of the apple phenolics used for cross-linking was determined by LC-ESE-MS. The apple phenolic extract contained significant amounts of quercetin glycosides, catechins and chlorogenic acid. The laccase cross-linked BLG in the presence of apple phenolics. The polymerization rendered the protein insoluble in the reaction mixture. Sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE) analysis of the cross-linking reaction mixture revealed a heterogeneous mixture of high molecular masses (cross-linked BLG), with a fraction of the BLG remaining monomeric. Enzymatic processing of BLG by laccase and apple polyphenols as mediators can decrease the bi-phasal pepsin- pancreatin digestibility of the monomeric and cross-linked protein, thus decreasing its nutritional value. In addition, reduced BLG digestibility can decrease its allergenic potential. Apple polyphenols can find usage in the creation of new, more functional food products, designed to prevent obesity and hypersensitivity-related disorders.

Apple juice intervention modulates expression of ARE-dependent genes in rat colon and liver

BACKGROUND

The risk of cancer and other degenerative diseases is inversely correlated with consumption of fruits and vegetables. This beneficial effect is mainly attributed to secondary plant constituents such as polyphenols, supposed to play a major role in protection against ROS (reactive oxygen species)-associated toxicity.

AIM OF THE STUDY

To elucidate the potential of differently manufactured apple juices (clear AJ/cloudy AJ/smoothie, in comparison with a polyphenol-free control juice) to modulate expression of ARE-dependent genes.

METHODS

In male Sprague-Dawley rats (n = 8/group; 10d juice intervention, 4d wash-out; 4 treatment cycles), expression of target genes (superoxide dismutase, SOD1/SOD2; glutathione peroxidase, GPX1/GPX2; γ-glutamylcysteine ligase, GCLC/GCLM; glutathione reductase, GSR; catalase, CAT; NAD(P)H:quinone oxidoreductase-1, NQO1 and transcription factor erythroid-derived 2-like-2, Nrf2) was quantified with duplex RT-PCR, using glyceraldehyde-3-phosphate dehydrogenase (GAPDH) as control.

RESULTS

In colon and liver of rats consuming polyphenol-free control juice, rather similar basic expressions were observed (relative GAPDH ratios ranging from 2 to 0.7 and 2.5-0.3, respectively). In the distal colon, apple juice intervention slightly but significantly induced most genes (e.g. GPX2, GSR, CAT, Nrf2; p < 0.001), whereas in the liver only GPX1 and NQO1 mRNA were up-regulated; other hepatic target genes were not affected or down-regulated (SOD1, SOD2, GCLC/M, GSR), concomitant with the absence of Nrf2 induction. Induction of antioxidant gene expression differed with juice type (cloudy AJ > clear AJ ~ smoothie).

CONCLUSION

Taken together, the results underline the potential of polyphenol-rich apple juice to increase the expression of ARE-dependent antioxidant genes.