Potent Inhibitory Effects of Quercetin on Inflammatory Responses of Collagen-Induced Arthritis in Mice.

BACKGROUND: Production of tumor necrosis factor (TNF)-α by inflammatory cells in lesions is the hallmark of the pathogenesis of rheumatoid arthritis (RA). Regulation of inflammatory responses in knee joints of patients with RA is critical for improving severe symptoms. Flavonoids have inhibitory effects on the acute and chronic inflammatory responses caused by TNF-α. The flavonoid quercetin (QUER) is one of the most prominent dietary antioxidants. OBJECTIVE: The present study investigated the preventive and therapeutic effects of QUER on inflammatory responses in collagen-induced arthritis (CIA) in mice. METHODS: Mice with CIA, a mouse model for RA, were treated with QUER orally three times a week either from the second immunization with collagen (day 21) or day 28 when symptoms of CIA had developed midway. RESULTS: In both cases, inflammation-related clinical scores of knee joints were significantly reduced by treatment with QUER. Histological analyses showed that the representative characteristics of RA, such as damage to interchondral joints, infiltration of inflammatory cells, and pannus formation, were significantly reduced by QUER treatment. Oral administration of QUER significantly decreases lipopolysaccharide (LPS)-induced TNF-α production in a dose-dependent manner. Expression of TNF- α mRNA in knee joints was decreased in QUER-treated mice, compared with those of CIA controls. CONCLUSION: These results suggest that oral administration of QUER might effectively improve symptoms of RA.

Morphometrical and Morphological Alterations of Human Leukocytes Exposed to 1.8 GHz Electromagnetic Radiations: In Vitro Protective Effects Induced by Polyphenols.

BACKGROUND: Our recent findings have demonstrated that electromagnetic radiations (EMR) (1.8 GHz radiofrequency) are able to in vitro induce morphometrical and morphological modifications of human leukocytes from normal donors. METHODS: In view of the evidence that polyphenols exert many beneficial effects on plants, animals and humans, leukocytes from human peripheral blood were pre-treated for 1 h with two polyphenol preparations from red grape before EMR exposure (1.8 GHz). RESULTS: Our data will show that polyphenol pre-treatment reverts to normality the morphology of irradiated leukocytes in comparison to irradiated cells only. Conversely, leukocyte morphometry seems to be not affected by this treatment. CONCLUSION: Here, we demonstrate that polyphenols are also able to normalize leukocyte morphology per se altered before as well as after irradiation. Finally, a working hypothesis aimed at clarifying the protective mechanisms exerted by polyphenols on irradiated leukocytes will be illustrated.

Potential use of dietary natural products, especially polyphenols, for improving type-1 allergic symptoms.

Type-1 allergic diseases consist of two phases. An inductive phase comprises IgE formation to allergens based on the immune system being biased to predominant T-helper type 2 responses. In a triggering phase allergic symptoms are triggered due to a robust secretion of mediators from mast cells and other cells after re-exposure to the same allergen. Various polyphenols, found in foods and plant sources, have potent anti-allergic activities that have been shown in different disease models and in human clinical trials. The present review summarizes the recent findings and progress in the research about polyphenols and natural products, and their role in allergic diseases. Intake of representative polyphenols (flavones, flavone-3-ols, catechins, anthocyanidins, flavanones, procyanidins, and resveratrol) can improve a skewed Th1/Th2 balance and suppress antigen-specific IgE antibody formation. Oral administration of fermented grape foods (FGF), one example of natural products fermented by lactic acid bacteria, is effective for decreasing allergic symptoms in the effector phase. Inhibitory mechanisms of polyphenols are also discussed.

Suppression of inflammatory responses after onset of collagen-induced arthritis in mice by oral administration of the Citrus flavanone naringin.

Rheumatoid arthritis (RA) is closely related to the pathogenesis of tumor necrosis factor α in lesions. We investigated the suppressive effects of a Citrus flavanone naringin on inflammatory responses in mice with collagen-induced arthritis (CIA), a mouse model for RA. To investigate potential preventive and therapeutic effects of naringin, mice were given naringin orally three times a week from the second immunization with collagen (day 21) and from day 31, when symptoms of CIA had reached a plateau, respectively. In both cases, inflammation-related clinical scores for knee joints were significantly reduced by administration of naringin. Histological analyses demonstrated that representative phenomena, such as damage to interchondral joints, infiltration of inflammatory cells and pannus formation, were significantly depressed by treatment with naringin. In addition, increases in the expression of high-mobility group box-1 protein in the joints of mice with CIA were suppressed by naringin. These results suggest that oral administration of naringin might be effective for treating human patients with RA.

Effects of antioxidant polyphenols on TNF-alpha-related diseases.

Oxidative stress and inflammatory responses sustained for a long period of time cause many diseases. A proinflammatory cytokine, tumor necrosis factor α (TNF-α), plays a pivotal role in the pathogenesis of chronic and auto-immune diseases. The present review, supplemented by hitherto unpublished data of the authors and their coworkers, shows that the intake of polyphenols contained in natural sources, such as hydroxytyrosol, tyrosol, oleuropein (olives), naringin and hesperidin (Citrus fruits), resveratrol, procyanidins or oligomeric procyanidin (grapes or grape seed extracts), (-)-epigallocatechin gallate (green tea) and quercetin (grapes, green tea) etc., are able to modulate chronic inflammatory diseases, such as type 2 diabetes, rheumatoid arthritis, inflammatory bowel disease, and affect the formation and interaction of advanced glycation end products with their respective receptors. Furthermore, potent activities of fermented grape marc, prepared as a fine lyophilized powder from fresh skin and seeds of a Japanese grape strain (Koshu) and then fermented with Lactobacillus plantarum, are described. Finally, the bioavailability of representative polyphenols will be discussed.

Suppression of type-I allergic responses by oral administration of grape marc fermented with Lactobacillus plantarum.

We investigated the inhibitory effects of fermented grape marc (FGM), lyophilized fine powder of skin, and seeds of Vitis vinifera Koshu grape prepared by fermentation with Lactobacillus plantarum, on type-I allergic responses in mice. Repeated oral administration of FGM, but not non-fermented grape marc (GM), to BALB/c mice primed with ovalbumin (OVA) resulted in a significant reduction of serum IgE levels, compared with those of immunized controls. After OVA challenge, increased numbers of eosinophils in bronchial alveolar lavage fluids (BALF) significantly decreased by treatment with FGM but not with GM. For passive cutaneous anaphylaxis (PCA) reaction, BALB/c mice received intradermal sensitization with anti-OVA IgE serum and were challenged intravenously with OVA containing Evans blue at 24 h after IgE sensitization. Oral administration of FGM at 30 min before OVA challenge significantly suppressed the PCA reaction. On the other hand, Lactobacillus alone and non-fermented GM did not show any suppressive effects. Interestingly, FGM samples prepared from grapes for red wine, such as Negroamaro (rich in resveratrol) or Tannat (rich in oligomeric procyanidin), did not suppress the reaction. These results indicate that oral administration of FGM, prepared from Koshu grape for white wine but not from grapes for red wine, could suppress both phases of type-I allergic responses. A fraction extractable with acetone was responsible for the suppressive effects of FGM.

Suppressive effects of the flavonoids quercetin and luteolin on the accumulation of lipid rafts after signal transduction via receptors.

Quercetin (QUER) and luteolin (LUTE) are dietary flavonoids capable of regulating the production of cytokines, such as tumor necrosis factor-alpha (TNF-alpha), and interleukin-6 (IL-6). However, their mechanisms of action are not fully understood. In lipopolysaccharide-triggered (LPS)-triggered signaling via Toll-like receptor 4 (TLR4), QUER and LUTE suppresses not only the degradation of the inhibitor of kappaB (IkappaB), with resultant activation of nuclear factor-kappaB (NF-kappaB), but also the phosphorylation of p38 and Akt in bone marrow-derived macrophages that have been stimulated with LPS. We report here that, in TNF-alpha-induced signaling, QUER and LUTE significantly suppressed the production of IL-6 and activation of NF-kappaB. Accumulation of lipid rafts, the initial step in the signaling pathway, was significantly inhibited when macrophages were treated with QUER or with LUTE prior to exposure to LPS. Similarly, the accumulation of lipid rafts was inhibited by the flavonoids when B cells were activated via the membrane IgM and when T cells were activated via CD3. In contrast, QUER and LUTE did not inhibit the activation of phorbol myristate acetate-induced NF-kappaB in macrophages. Our observations suggest that QUER and LUTE interact with receptors on the cell surface and suppress the accumulation of lipid rafts that occurs downstream of the activation of the receptors.

Quercetin but not luteolin suppresses the induction of lethal shock upon infection of mice with Salmonella typhimurium.

Tumor necrosis factor-alpha (TNF-alpha) is important for the induction of systemic inflammatory responses that lead to lethal shock. Quercetin and luteolin, which differ by one hydroxyl group, are known to suppress the lipopolysaccharide-induced production of TNF-alpha in vitro. We show differing inhibitory effects of quercetin and luteolin on the induction of lethal shock in Salmonella typhimurium aroA-infected mice. In a time- and dose-dependent manner, quercetin reduced the plasma levels of TNF-alpha, lowered bacterial titers in livers, prevented liver damage and prolonged survival, while luteolin had little or no effect. Compared with luteolin, quercetin increased the infiltration of Gr-1(+)CD69(+) neutrophils into the peritoneal cavity and lowered heat shock protein 70 expression. Obviously, the additional hydroxyl group in quercetin is important for suppressing infection-induced lethal shock in mice.

Effects of alpha-glucosylhesperidin, a bioactive food material, on collagen-induced arthritis in mice and rheumatoid arthritis in humans.

Hesperidin (Hsp) is an abundant flavonoid in citrus fruits, and the oral administration of Hsp has been recently reported to suppress collagen-induced arthritis in mice. Therefore, we sought to determine whether alpha-glucosylhesperidin (Hsp-G), which is an Hsp derivative with enhanced water-solubility, is effective on treating arthritis in both mice and humans. Hsp-G was orally administered to mice with collagen-induced arthritis, and its effects were evaluated clinically and histologically. Oral administration of Hsp-G improved collagen-induced arthritis when administered before the onset of arthritis as well as when administered after its onset. A decrease in tumor necrosis factor-alpha production was found to cause this improvement. In the human study, 19 patients with rheumatoid arthritis (RA) were enrolled in a 12-week double-blind, placebo-controlled trial. Patients were administered beverages containing 3 g Hsp-G (n = 9) or placebo (n = 10) every morning for the duration of the 3-month trial. Additionally, patients received standard therapy from a physician every 4 weeks. As a result, 3 of 9 patients in the Hsp-G group improved, while only 1 of 10 patients in the placebo group improved; this was in accordance with the American College of Rheumatology criteria. The present study revealed that the food material Hsp-G was effective when administered with standard anti-rheumatoid therapy in ameliorating RA in mice and humans without any adverse effects and may improve the quality of life for patients with RA as a complementary/alternative medicine.

Effects of isoflavones and soybeans fermented with Bacillus subtilis on lipopolysaccharide-induced production of tumor necrosis factor-alpha and fibrinolysis in vivo.

The effects of isoflavones and of a derivative of soybeans fermented with Bacillus subtilis, designated Nattoesse, on the lipopolysaccharide (LPS)-induced production of tumor necrosis factor-alpha (TNF-alpha) and fibrinolysis were investigated in vivo. The dietary supplement Nattoesse contains several isoflavones. Therefore, we examined the effects of individual isoflavones (daidzein, daidzin, genistein, and genistin) on the LPS-induced production of TNF-alpha. Intraperitoneal injections of daidzein, daidzin, and genistin (but not of genistein before a challenge with LPS) resulted in significant depression of serum levels of TNF-alpha in mice. Daidzein had the strongest activity in this assay. Oral administration of daidzein to mice also had a significant suppressive effect, as compared with that of the Citrus flavanone naringin. In galactosamine-sensitized mice, by contrast, the suppression of LPS-induced lethal shock by daidzein was very weak. Nattoesse did not inhibit the production of TNF-alpha nor did it prevent lethal shock. However, oral administration of Nattoesse to mice significantly suppressed LPS-induced increases in scores of the fibrin degradation product, and the effect was both dose- and time-dependent. Thus, it appears that Nattoesse has fibrinolytic activity during LPS-induced circulatory failure.

Immunomodulating effects of flavonoids on acute and chronic inflammatory responses caused by tumor necrosis factor alpha.

Flavonoids have beneficial activities which modulate oxidative stress, allergy, tumor growth and viral infection, and which stimulate apoptosis of tumor cells. In addition to these activities, dietary flavonoids are able to regulate acute and chronic inflammatory responses. Here we describe new aspects of regulatory mechanisms by which flavonoids suppress production of tumor necrosis factor-alpha (TNF-alpha) by macrophages, microglial cells and mast cells stimulated with lipopolysaccharide (LPS) and others via toll-like receptors (TLRs), and TNF-alpha-mediated acute and chronic inflammatory responses. Treatment with flavonoids such as luteolin, apigenin, quercetin, genistein, (-)-epigallocatechin gallate, and anthocyanidin resulted in significant downregulation of LPS-elicited TNF-alpha and nitric oxide (NO) production and diminished lethal shock. In chronic diseases, pathogenesis of collagen-induced arthritis (CIA), a mouse model of rheumatoid arthritis which is triggered by TNF-alpha, was improved by the oral administration of flavonoids after the onset of CIA. Here, we discuss that inhibitory effects of flavonoids on acute and chronic inflammation are due to regulation of signaling pathways, including the nuclear factor kappaB (NF-kappaB) activation and mitogen-activated protein (MAP) kinase family phosphorylation. FcetaRI expression by NF-kappaB activation was also reduced by flavonoids; while accumulation of lipid rafts, which is the critical step for signaling, was blocked by flavonoids. The intake of dietary flavonoids reduces acute and chronic inflammation due to blocking receptor accumulation and signaling cascades, and would assist individuals at high-risk from life-style related diseases.

Suppression of collagen-induced arthritis by oral administration of the citrus flavonoid hesperidin.

The preventive and therapeutic effects of the Citrus flavonoid hesperidin (HES) on the development of collagen-induced arthritis (CIA), a mouse model of rheumatoid arthritis (RA), were investigated. Mice were administered orally HES three times a week starting from either the onset (day 21) of secondary immunization or on day 31, when the CIA development had reached a plateau. In both cases, treatment with HES resulted in a significant suppression of clinical scores and improvement of histological features. These results suggest that oral administration of HES could be effective for treating human RA patients.

Limitation of polymyxin B on suppression of endotoxin shock induced by Salmonella infection in mice.

The protective effects of an antibiotic polymyxin B (PLB), having lipopolysaccharide (LPS)-binding activity, on infection-induced endotoxin shock in mice were investigated. Infection with 10(8) colony forming units of an attenuated Salmonella typhimurium aroA strain caused lethal endotoxin shock to ddY mice. Treatment with PLB 1 h post infection (p.i.) resulted in significant reduction of mortality and bacterial numbers in livers. In addition, treatment with PLB 1 h p.i. resulted in a transient increase at the early stage and gradual decline in plasma LPS levels. Although plasma levels of sCD14 and high mobility group box chromosomal protein-1 (HMGB-1) increased according with progression of infection, increases in plasma levels of sCD14 and HMGB-1 were downregulated by treatment with PLB 1 h p.i. However, the lethal shock was not blocked by treatment with anti-CD14 monoclonal antibody at 3 h and 6 h p.i. Interestingly, administration of PLB 6 h p.i. did not show any protective activities, indicating that a time window for effective PLB action is present.

A citrus flavonoid hesperidin suppresses infection-induced endotoxin shock in mice.

Administration of a citrus flavonoid hesperidin (HES) to mice before LPS challenge significantly reduced tumor necrosis factor (TNF)-alpha production in a dose-dependent manner. Treatment of HES 3 h before intraperitoneal (i.p.) infection with 10(8) CFU Salmonella typhimurium aroA resulted in rescue from lethal shock as similar to LPS-nonresponder mice. Not only bacterial numbers in livers and spleens but also plasma LPS levels significantly decreased by pretreatment with HES. In addition, HES markedly suppressed plasma levels of TNF-alpha and high mobility group box chromosomal protein 1 (HMGB-1), decreased the number of apoptotic cells in livers and normalized the activated states of blood coagulation factors such as prothrombin time and platelet numbers caused by infection. Pretreatment of LPS with HES suppressed the chromogenic Limulus reaction.

Potentiation of cytotoxic activity in naïve and tumor-bearing mice by oral administration of hot-water extracts from Agaricus brazei fruiting bodies.

When hot-water extracts of mushroom Agaricus brazei MURRILL fruiting bodies (Agaricus extracts) were administered orally into Meth A-bearing mice, tumor growth was significantly inhibited compared with controls given water orally. Treatment with Agaricus extracts for five successive days significantly increased natural killer activity of spleen cells in naïve BALB/c mice. In Meth A-bearing BALB/c mice, Agaricus extracts enhanced the induction of antigen-specific cytotoxic T lymphocytes and interferon gamma production, indicating that Agaricus extracts potentiate cytotoxic activity in innate and adaptive immunity.

Suppression of infection-induced endotoxin shock in mice by a citrus flavanone naringin.

The protective effect of the Citrus flavanone naringin was demonstrated in an endotoxin shock model based on Salmonella infection. Intraperitoneal ( i. p.) infection with 10 (8) CFU Salmonella typhimurium aroA caused lethal shock in lipopolysaccharide (LPS) -responder but not LPS-non-responder mice. Administration of 1 mg naringin 3 h before infection resulted in protection from lethal shock, similar to LPS-non-responder mice. The protective effect of naringin was time- and dose-dependent. Treatment with naringin resulted not only in a significant decrease in bacterial numbers in spleens and livers, but also in a decrease in plasma LPS levels. In addition, naringin markedly suppressed TNF-alpha and normalized the activated states of blood coagulation factors such as prothrombin time, fibrinogen concentration and platelet numbers caused by infection. Interestingly, treatment with naringin suppressed high levels of soluble CD14 and high mobility group-1 molecule caused by infection.

Inhibitory effect of quercetin on carrageenan-induced inflammation in rats.

We examined the effect of quercetin on the inflammatory response induced by carrageenan in the rat. Air pouches were induced subcutaneously on the backs of rats and injected with carrageenan. The rats were treated with either vehicle or quercetin at a dose of 10 mg/kg one hour before carrageenan challenge. Fourty-eight hour after carrageenan challenge, the air pouches were removed and analyzed. The volume, protein amounts and cell counts in the exudation obtained from the quercetin-treated animals were significantly reduced compared to those from vehicle-treated animals. The contents of PGE(2), TNF-alpha, RANTES, MIP-2 and the mRNA for cyclooxygenase-2 were also suppressed in these rats. The histological examination displayed the suppression of the inflammatory response in the pouch tissues from quercetin-treated rats. As the anti-inflammatory effect of the flavonols was more or less at the similar level among the quercetin-, isoquercitrin- or rutin-treated rats, it appeared that the sugar parts did not influence on the anti-inflammatory effect. Our study indicated that the flavonols modulated the inflammatory response, at least in part, by modulating the prostanoid synthesis as well as cytokine production.

Time- and dose-dependent effect of fosfomycin on suppression of infection-induced endotoxin shock in mice.

Therapeutic effects of fosfomycin (FOF) and imipenem (IPM) were investigated in a novel model for endotoxin shock that was caused by intraperitoneal (i.p.) infection with 10(8) colony forming units of attenuated Salmonella typhimurium. Acute lethal shock was observed in BALB/c and ddY but not in lipopolysaccharide (LPS)-nonresponder BALB/lps(d) mice. Effects of FOF, but not its enantiomer, and IPM were dose- and time-dependent, since therapeutic efficacy was demonstrated in mice injected i.p. or orally at doses of more than 20 mg/kg 15 min before or 1 h after infection. Treatment with FOF 1 h postinfection (p.i.) resulted in significant decreases in bacterial numbers in spleen and liver, suggesting that the antimicrobial activity of FOF seems to closely correlate to suppression of infection-induced lethal shock. Regarding coagulation systems, FOF inhibited increase in the prothrombin time but upregulated fibrinogen concentration. Plasma levels of LPS released from bacilli were significantly higher in FOF- than IPM-treated mice and infection controls, but both antibiotics showed similar efficacy in protection.