Citrus pectin affects cytokine production by human peripheral blood mononuclear cells

Orange juice and its major polyphenol hesperidin consumption do not induce immunomodulation in healthy well-nourished humans

BACKGROUND & AIMS

Polyphenols exert a variety of biological properties, including antioxidant, immunomodulatory and antigenotoxic effects. In a randomized crossover study in healthy men, we investigated the effects of orange juice and its major polyphenolic compound hesperidin on a panel of immune cell functions, including cytokine secretion by leukocytes, lytic activity of NK cells, and the Reactive Oxygen Species (ROS) burst by polymorphonuclear neutrophil cells (PMN).

METHODS

The protocol design was divided into three 4-week treatment periods separated by 3-week wash-out intervals, for total study duration of 18 weeks. During treatment periods, volunteers (n = 24) consumed daily 500 mL of orange juice, or an isocaloric control beverage with hesperidin (292 mg in a capsule), or of the same control beverage with a placebo.

RESULTS

Whatever the intake was, no variations were recorded on leukocyte subset distributions (PMN, B and T lymphocytes, NK cells and monocytes), ROS production by stimulated PMNs, lytic activity of NK cells or cytokine production capacity of leukocytes in well-nourished healthy volunteers.

CONCLUSIONS

We show that consumption within the usual daily intake range of orange juice and its major polyphenol hesperidin do not induce immunomodulation of cell immune function in healthy well-nourished humans.

Activation of human T-helper/inducer cell, T-cytotoxic cell, B-cell, and natural killer (NK)-cells and induction of natural killer cell activity against K562 chronic myeloid leukemia cells with modified citrus pectin

BACKGROUND

Modified citrus pectin (MCP) is known for its anti-cancer effects and its ability to be absorbed and circulated in the human body. In this report we tested the ability of MCP to induce the activation of human blood lymphocyte subsets like T, B and NK-cells.

METHODS

MCP treated human blood samples were incubated with specific antibody combinations and analyzed in a flow cytometer using a 3-color protocol. To test functionality of the activated NK-cells, isolated normal lymphocytes were treated with increasing concentrations of MCP. Log-phase PKH26-labeled K562 leukemic cells were added to the lymphocytes and incubated for 4 h. The mixture was stained with FITC-labeled active form of caspase 3 antibody and analyzed by a 2-color flow cytometry protocol. The percentage of K562 cells positive for PKH26 and FITC were calculated as the dead cells induced by NK-cells. Monosaccharide analysis of the MCP was performed by high-performance anion-exchange chromatography with pulse amperometric detection (HPAEC-PAD).

RESULTS

MCP activated T-cytotoxic cells and B-cell in a dose-dependent manner, and induced significant dose-dependent activation of NK-cells. MCP-activated NK-cells demonstrated functionality in inducing cancer cell death. MCP consisted of oligogalacturonic acids with some containing 4,5-unsaturated non-reducing ends.

CONCLUSIONS

MCP has immunostimulatory properties in human blood samples, including the activation of functional NK cells against K562 leukemic cells in culture. Unsaturated oligogalacturonic acids appear to be the immunostimulatory carbohydrates in MCP.

Pectin from Passiflora edulis shows anti-inflammatory action as well as hypoglycemic and hypotriglyceridemic properties in diabetic rats

Flour made from Passiflora edulis fruit peel has been used in Brazil to treat diabetes. This study evaluated the effects of pectin from P. edulis on rats with alloxan-induced diabetes, on myeloperoxidase release from human neutrophils, and on carrageenan-induced paw edema. In the experiments on carrageenan-induced paw edema, paws were dissected for hematoxylin-eosin staining and immunohistochemistry determinations of tumor necrosis factor-α and inducible nitric oxide synthase. Male Wistar rats were divided into the following groups: diabetic controls and diabetic treated with pectin daily for 5 days (0.5-25 mg/kg orally). Glibenclamide and metformin were used as reference drugs. Forty-eight hours after alloxan administration, blood measures were determined (before treatment) and again 5 days later (after treatment). Pectin decreased blood glucose and triglyceride levels in diabetic rats. Pectin also decreased edema volume and release of myeloperoxidase (0.1-100 μg/mL). It also significantly decreased neutrophil infiltration and partially decreased immunostaining for tumor necrosis factor-α and inducible nitric oxide synthase. In conclusion, these data indicated that pectin, a bioactive compound present in P. edulis, has potential as a useful alternative treatment for type 2 diabetes. Its anti-inflammatory properties are probably involved in its antidiabetic action.

Transcription profiles of LPS-stimulated THP-1 monocytes and macrophages: a tool to study inflammation modulating effects of food-derived compounds

An assay was developed to study inflammation-related immune responses of food compounds on monocytes and macrophages derived from THP-1 cell line. First strategy focused on the effects after stimulation with either lipopolysaccharide (LPS) or Concanavalin A (ConA). Gene expression kinetics of inflammation-related cytokines (IL-1β, IL-6, IL-8, IL-10 and TNF-α), inflammation-related enzymes (iNOS and COX-2), and transcription factors (NF-κB, AP-1 and SP-1) were analyzed using RT-PCR. Time dependent cytokine secretion was investigated to study the inflammation-related responses at protein level. LPS stimulation induced inflammation-related cytokine, COX-2 and NF-κB genes of THP-1 monocytes and THP-1 macrophages with the maximum up-regulation at 3 and 6 h, respectively. These time points, were subsequently selected to investigate inflammation modulating activity of three well known immuno-modulating food-derived compounds; quercetin, citrus pectin and barley glucan. Co-stimulation of LPS with either quercetin, citrus pectin, or barley glucan in THP-1 monocytes and macrophages showed different immuno-modulatory activity of these compounds. Therefore, we propose that simultaneously exposing THP-1 cells to LPS and food compounds, combined with gene expression response analysis are a promising in vitro screening tool to select, in a limited time frame, food compounds for inflammation modulating effects.

Lycopene phytocomplex, but not pure lycopene, is able to trigger apoptosis and improve the efficacy of photodynamic therapy in HL60 human leukemia cells

We compared the ability of pure lycopene (Lyco) versus lycopene phytocomplex (LycoC) to induce apoptosis in vitro. We found that LycoC, but not Lyco, was able to trigger apoptosis in HL60 cells, as documented by subdiploid DNA content and phosphatidylserine exposure. LycoC-induced apoptosis was associated with reactive oxygen species (ROS) generation and loss of mitochondrial transmembrane potential, suggesting that LycoC triggered apoptosis via a mitochondrial pathway. We also verified the redox state of cells by measuring glutathione (GSH) content, but only a small percentage of cells showed GSH depletion, suggesting that the loss of GSH may be a secondary consequence of ROS generation. Moreover, LycoC pretreatment effectively increased apoptosis induced by photodynamic therapy (PDT), a mode of cancer treatment using a photosensitizer and visible light. LycoC pretreatment was even more potent in improving PDT than pretreatment with ascorbic acid or alpha-tocopherol (or the two combined). Our results demonstrate that LycoC has a stronger cytotoxic effect than Lyco and is a better source of agents able to trigger apoptosis in HL60 cells and improve the efficacy of PDT in vitro.