Modulation of cytokine secretion by garlic oil derivatives is associated with suppressed nitric oxide production in stimulated macrophages

Dietary Organosulfur-Containing Compounds and Their Health-Promotion Mechanisms

Dietary organosulfur-containing compounds (DOSCs) in fruits, vegetables, and edible mushrooms may hold the key to the health-promotion benefits of these foods. Yet their action mechanisms are not clear, partially due to their high reactivity, which leads to the formation of complex compounds during postharvest processing. Among postharvest processing methods, thermal treatment is the most common way to process these edible plants rich in DOSCs, which undergo complex degradation pathways with the generation of numerous derivatives over a short time. At low temperatures, DOSCs are biotransformed slowly during fermentation to different metabolites (e.g., thiols, sulfides, peptides), whose distinctive biological activity remains largely unexplored. In this review, we discuss the bioavailability of DOSCs in human digestion before illustrating their potential mechanisms for health promotion related to cardiovascular health, cancer chemoprevention, and anti-inflammatory and antimicrobial activities. In particular, it is interesting that different DOSCs react with glutathione or cysteine, leading to the slow release of hydrogen sulfide (H2S), which has broad bioactivity in chronic disease prevention. In addition, DOSCs may interact with protein thiol groups of different protein targets of importance related to inflammation and phase II enzyme upregulation, among other action pathways critical for health promotion.

Expected final online publication date for the Annual Review of Food Science and Technology, Volume 13 is March 2022. Please see http://www.annualreviews.org/page/journal/pubdates for revised estimates.

Hepatoprotective Effect of Mixture of Dipropyl Polysulfides in Concanavalin A-Induced Hepatitis

The main biologically active components of plants belonging to the genus Allium, responsible for their biological activities, including anti-inflammatory, antioxidant and immunomodulatory, are organosulfur compounds. The aim of this study was to synthetize the mixture of dipropyl polysulfides (DPPS) and to test their biological activity in acute hepatitis. C57BL/6 mice were administered orally with DPPS 6 h before intravenous injection of Concanavalin A (ConA). Liver inflammation, necrosis and hepatocytes apoptosis were determined by histological analyses. Cytokines in liver tissue were determined by ELISA, expression of adhesive molecules and enzymes by RT PCR, while liver mononuclear cells were analyzed by flow cytometry. DPPS pretreatment significantly attenuated liver inflammation and injury, as evidenced by biochemical and histopathological observations. In DPPS-pretreated mice, messenger RNA levels of adhesion molecules and NADPH oxidase complex were significantly reduced, while the expression of SOD enzymes was enhanced. DPPS pretreatment decreased protein level of inflammatory cytokines and increased percentage of T regulatory cells in the livers of ConA mice. DPPS showed hepatoprotective effects in ConA-induced hepatitis, characterized by attenuation of inflammation and affection of Th17/Treg balance in favor of T regulatory cells and implicating potential therapeutic usage of DPPS mixture in inflammatory liver diseases.

The Garlic Compound Z-Ajoene, S-Thiolates COX2 and STAT3 and Dampens the Inflammatory Response in RAW264.7 Macrophages

SCOPE

Garlic (Allium sativum) has been used for centuries as a prophylactic and therapeutic medicinal agent to control inflammation-associated pathologies. To investigate the underlying mechanisms, an in vitro inflammatory model is established using RAW264.7 murine macrophages exposed to low-doses of lipopolysaccharide (LPS) in the presence of garlic compounds allicin and Z-ajoene (ZA), mimicking regular garlic consumption.

METHODS AND RESULTS

Both allicin and Z-ajoene dampen both transcript and protein expression of the pro-inflammatory cytokines IL1β, IL6, and IL12β, and upregulate the expression of the anti-inflammatory cytokine IL10. Protein arrays of selected secreted inflammatory mediators confirm that Z-ajoene has a pronounced down-regulatory effect on LPS-induced inflammatory cytokines and chemokines. Many of these proteins are known targets of the transcription factor signal transducer and activator of transcription 3 (STAT3); and indeed, Z-ajoene or its analogue dansyl-ajoene is found to decrease phosphorylation and nuclear translocation of STAT3, and to covalently modify the protein by S-thiolation at Cys108, Cys367, and Cys687. Z-Ajoene dose-dependently and non-competitively inhibit the activity of cyclooxygenase 2 (COX2), possibly attributed to S-thiolation at Cys9 and Cys299.

CONCLUSION

The characterization of Z-ajoene's activity of targeting and covalently modifying STAT3 and COX2, both important regulators of inflammation, may contribute to the health benefits of regular dietary garlic consumption.

Immunomodulatory effect of diallyl sulfide on experimentally-induced benign prostate hyperplasia via the suppression of CD4+T/IL-17 and TGF-β1/ERK pathways

Benign prostatic hyperplasia (BPH) is a nonmalignant enlargement of the prostate common in older men. Diallyl sulfide (DAS), a major component of garlic, has been reported to possess antioxidant, anti-inflammatory, and antiproliferative effects. However, the underlying protective immunomodulatory mechanism of DAS on BPH remains vague. Herein, experimental BPH was induced in rats by daily subcutaneous injection of testosterone propionate (TP) (3 mg/kg, s.c.) for 4 weeks. In parallel, finasteride (Fin) (5 mg/kg, p.o) or DAS (50 mg/kg, p.o.) was administered orally during BPH induction. TP-induced histological alterations and the immune-inflammatory cascade. On the other hand, DAS or Fin administration alleviated all abnormalities induced testosterone. Fin and DAS administration markedly reduced prostate weight by 53% with Fin, and by 60% with DAS. Moreover, serum testosterone and DHT were reduced by 55% and 52%, respectively, with Fin and by 68% and 75%, respectively, with DAS, in concordance with decreased protein expression of androgen receptor (AR), and prostate-specific antigen (PSA). Furthermore, both regime lessen immune-inflammatory milieu, as evidenced by decrease CD4+ T-cells protein expression and associated inflammatory cytokines. Concomitantly, Fin and DAS exhibited marked mitigation in insulin-like growth factor-1 (IGF-1), transforming growth factor-beta1 (TGF-β1), and phosphorylated extracellular signal-regulated kinase (ERK1/2) signaling. Besides alleviating oxidative stress by 53% and 68% in prostatic MDA and by 27% and 7% in prostatic iNOS with Fin and DAS, respectively. In conclusion, this work highlighted a potential therapeutic approach of DAS as a dietary preventive agent against BPH via its anti-inflammatory and immunomodulatory effect along with suppression of the ERK pathway.

Organosulfur Compounds: A Review of Their Anti-inflammatory Effects in Human Health

Phytonutrients are widely recognized for providing protective human health benefits. Among the phytonutrients, epidemiological and experimental studies show that dietary organosulfur compounds (OSC) play a significant role in preventing various human pathological progressions, including chronic inflammation, by decreasing inflammatory mediators such as nitric oxide (NO), prostaglandin (PG)E₂, interleukin (IL)-1β, IL-6, tumor necrosis factor (TNF)-α, and IL-17, which are all typical hallmarks of inflammation. Evidence supports OSC in reducing the expression of these markers, thereby attenuating chronic inflammatory processes. Nuclear factor-kappa B (NF-κB) is a key regulating factor during inflammation, and novel evidence shows that OSC downregulates this transcriptional factor, thus contributing to the anti-inflammatory response. In vitro and in vivo studies show that inflammation is mechanistically linked with acute and chronic pathological conditions including cancer, diabetes, obesity, neural dysfunction, etc. Furthermore, a considerable number of experiments have demonstrated that the anti-inflammatory properties of OSC occur in a dose-dependent manner. These experiments also highlight indirect mechanisms as well as potent co-functions for protective roles as antioxidants, and in providing chemoprotection and neuroprotection. In this brief review, we provided an overview of the anti-inflammatory effects of OSC and elucidated probable mechanisms that are associated with inflammation and chronic disorders.

Diallyl Disulfide Mitigates DNA Damage and Spleen Tissue Effects After Irradiation

BACKGROUND Several factors found in foods are beneficial to human health and they may contribute to radiation protection. Taking food factors could be an easy way to reduce the effects of radiation after nuclear accidents, as well as secondary radiation risks after cancer radiotherapy or space missions. Here, diallyl disulfide (DADS), a component of garlic oil, was studied for its ability to mitigate radiation damage. MATERIAL AND METHODS We investigated the effects of DADS on micronucleus (MN) formation and apoptosis in HepG2 cells by use of 4-Gy X-ray irradiation. We also assessed the effects of DADS on radiation damage in vivo by evaluating MN formation in bone marrow cells in mice (BALB/c, 8-week-old females) after oral intake of DADS prior to irradiation with 4 Gy. Several tissue effects were also investigated. RESULTS The presence of DADS inhibited MN formation, whereas DADS had no influence on the radiation-induced inhibition of cell cycle progression in HepG2 cells. An increase in apoptosis in HepG2 cells was induced after irradiation, and this effect was stronger in the presence of DADS than in its absence. In mice, when DADS was administered daily for 3 days prior to irradiation, MN formation in irradiated mice was decreased. The decrease in MN formation in mice was greater with 0.5% DADS compared to 1% DADS. Moreover, an increase in spleen weight observed 3 weeks after irradiation was suppressed in mice administered DADS. CONCLUSIONS DADS is a potential radiation-protective agent that effectively mitigates DNA damage, and its effects in the spleen observed after irradiation may be related to inflammation and carcinogenesis.

Garlic and ginger extracts modulated broiler chicks innate immune responses and enhanced multidrug resistant Escherichia coli O78 clearance

Administration of antibiotics as feed additives in broilers resulted in prompting of some undesirable effects such as the rising emergence of multi-drug resistant (MDR) bacteria, so scrutinizing for new alternatives like herbs is the up to date task for global health. This study was designed to determine the in-vitro antibacterial and ex-vivo immunomodulatory efficacy of garlic (Allium sativum) and ginger (Zingiber officinale) extracts post dietary supplementation for 900-one-day-old Sasso broiler chicks. The in-vivo protective actions of these extracts against avian pathogenic MDR Escherichia coli (E. coli) O78 challenge was evaluated after 21 days of extracts supplementation. Garlic extract exhibited broader antimicrobial spectra against MDR E. coli O78 and S. aureus isolates. Through the 21 days of garlic or ginger dietary supplementation, the chicks' innate immune response was modulated via various mechanisms including phagocytosis augmentation, bactericidal activity enhancement and nitric oxide (NO) production reduction, together with triggering the IL-1β, IL-6 and IFN-γ cytokines expression levels in comparison with the non-supplemented chicks. It is tempting to speculate that protection against pathogenic E. coli O78 challenge was high in chicks supplemented with each individual extract with severe reduction in the bacterial colony forming units in chicks' vital organs that confirm the extracts immunomodulatory activity and provide a mechanism(s) of their protective actions. Our data suggest promising useful insights to garlic and ginger dietary supplementation in broilers that may be safe for consumers from antibiotic toxic metabolites' residues and protective against the risk of infection with bacterial pathogens.

Novel Hybrid Conjugates with Dual Suppression of Estrogenic and Inflammatory Activities Display Significantly Improved Potency against Breast Cancer

In this work, we developed a small library of novel OBHS-RES hybrid compounds with dual inhibition activities targeting both the estrogen receptor α (ERα) and NF-κB by incorporating resveratrol (RES), a known inhibitor of NF-κB, into a privileged indirect antagonism structural motif (OBHS, oxabicycloheptene sulfonate) of estrogen receptor (ER). The OBHS-RES conjugates could bind well to ER and showed remarkable ERα antagonistic activity, and they also exhibited excellent NO inhibition in macrophage RAW 264.7 cells. Compared with 4-hydroxytamoxifen, some of them showed better antiproliferative efficacy in MCF-7 cell lines with IC₅₀ up to 3.7 μM. In vivo experiments in a MCF-7 breast cancer model in Balb/c nude mice indicated that compound 26a was more potent than tamoxifen. Exploration of the compliancy of the structure against ER specificity utilizing these types of isomeric three-dimensional ligands indicated that one enantiomer had much better biological activity than the other.

Chemical and Biological Properties of S-1-Propenyl-l-Cysteine in Aged Garlic Extract

S-1-Propenyl-l-cysteine (S1PC) is a stereoisomer of S-1-Propenyl-l-cysteine (SAC), an important sulfur-containing amino acid that plays a role for the beneficial pharmacological effects of aged garlic extract (AGE). The existence of S1PC in garlic preparations has been known since the 1960's. However, there was no report regarding the biological and/or pharmacological activity of S1PC until 2016. Recently, we performed a series of studies to examine the chemical, biological, pharmacological and pharmacokinetic properties of S1PC, and obtained some interesting results. S1PC existed only in trace amounts in raw garlic, but its concentration increased almost up to the level similar of SAC through aging process of AGE. S1PC showed immunomodulatory effects in vitro and in vivo, and reduced blood pressure in a hypertensive animal model. A pharmacokinetic study revealed that S1PC was readily absorbed after oral administration in rats and dogs with bioavailability of 88-100%. Additionally, S1PC had little inhibitory influence on human cytochrome P450 activities, even at a concentration of 1 mM. Based on these findings, S1PC was suggested to be another important, pharmacologically active and safe component of AGE similar to SAC. In this review, we highlight some results from recent studies on S1PC and discuss the potential medicinal value of S1PC.

The Anti-Inflammatory and Vasodilating Effects of Three Selected Dietary Organic Sulfur Compounds from Allium Species

The anti-inflammatory and vasodilating effects of three selected dietary organic sulfur compounds (OSC), including diallyl disulfide (DADS), dimethyl disulfide (DMDS), and propyl disulfide (PDS), from Allium species were investigated. In the anti-inflammatory activity assay, the three OSC demonstrated significant inhibition of nitric oxide (NO) and prostaglandin E₂ (PGE₂) production in LPS-induced RAW 264.7 cells. The expression of inducible nitric oxide synthase (iNOS) and cyclooxygenase (COX-2) in activated RAW 264.7 cells was inhibited by the three OSC, indicating that the three OSC prevented the LPS-induced inflammatory response in RAW 264.7 cells. For the vasodilative assay, the three OSC were ineffective in producing NO in SVEC4-10 cells, but they did enhance prostacyclin (PGI₂) production. The expression of COX-2 in SVEC4-10 cells was activated by DADS and DMDS. Pretreatment of SVEC4-10 cells with the three OSC decreased ROS generation in H₂O₂-induced SVEC4-10 cells. In addition, the three OSC significantly inhibited angiotensin-I converting enzyme (ACE). The up-regulation of PGI₂ production and COX-2 expression by DADS and DMDS and the reduction of ROS generation by DADS, DMDS, and PDS in SVEC4-10 cells contributed to the vasodilative effect of the three OSC. Collectively, these findings suggest that DADS, DMDS, and PDS are potential anti-inflammatory and vasodilative mediators.

Garlic oil inhibits dextran sodium sulfate-induced ulcerative colitis in rats

AIMS

Garlic oil (GO) is used for centuries in folk medicine as a therapy for many diseases including inflammatory disorders. Recently, it has exhibited potent anti-oxidant, anti-inflammatory and immunomodulatory effects. Consequently, we evaluated the possible protective effect of GO in a rat model of colitis, induced by dextran sulfate sodium (DSS).

MAIN METHODS

Colitis induced by allowing rats a free access to drinking water containing 5% DSS for 7 days, from day 1 to day 7. GO was administered orally in doses of 25, 50 and 100mg/kg/day. Mesalazine used as a standard medication in a dose of 15 mg/kg/day. All animals fasted for 2h, 1h before and 1h after giving the treatment, which introduced daily for 7 days, from day 1 to day 7, at 10:00 to 11:00 A.M. Animal body, and colonic weights, colonic myeloperoxidase (MPO), and superoxide dismutase (SOD) activities, colonic reduced-glutathione (GSH), malondialdehyde (MDA), tumor necrosis factor-α (TNF-α), interleukin (IL)-1β, and IL-10 levels, macroscopic and microscopic changes of colonic tissues were evaluated.

KEY FINDINGS

GO treatment significantly suppressed the elevated colonic weight, MPO activity, MDA, TNF-α and IL-1β levels. However, it potentiated the decrease body weight, colonic SOD activity, GSH and IL-10 levels. Moreover, it ameliorated the marked macroscopic and microscopic changes of colonic mucosa in a dose dependent manner.

SIGNIFICANCE

Garlic oil inhibits DSS-induced colitis in rats may be through its anti-oxidant, anti-inflammatory and immunomodulatory properties. Therefore, GO could be a promising protective agent recommended for UC patients.

Diallyl Sulfide and Its Role in Chronic Diseases Prevention

Diallyl sulfide (C₆H₁₀S, DAS) is one of the novel natural organosulfur compounds, which is mostly obtained from the genus Allium plants. Numerous studies have revealed several unique properties of DAS in terms of its health-promoting effects. DAS has proved to be anticancer, antimicrobial, anti-angiogenic, and immunomodulatory like unique functions as demonstrated by the multiple investigations. Diallyl sulfide can also impede oxidative stress and chronic inflammation as suggested by the literature. Studies also explored that DAS could thwart the development of chronic diseases like cancer, neuronal, cardiovascular disease through modulating mechanistic pathways involved in pathogenesis. In this book chapter, we have attempted to give the comprehensive view on DAS about the physiochemical and biological properties, and its preventive role in chronic diseases with a mechanistic overview.

Garlic and onions: their cancer prevention properties

The Allium genus includes garlic, onions, shallots, leeks, and chives. These vegetables are popular in cuisines worldwide and are valued for their potential medicinal properties. Epidemiologic studies, while limited in their abilities to assess Allium consumption, indicate some associations of Allium vegetable consumption with decreased risk of cancer, particularly cancers of the gastrointestinal tract. Limited intervention studies have been conducted to support these associations. The majority of supportive evidence on Allium vegetables cancer-preventive effects comes from mechanistic studies. These studies highlight potential mechanisms of individual sulfur-containing compounds and of various preparations and extracts of these vegetables, including decreased bioactivation of carcinogens, antimicrobial activities, and redox modification. Allium vegetables and their components have effects at each stage of carcinogenesis and affect many biologic processes that modify cancer risk. This review discusses the cancer-preventive effects of Allium vegetables, particularly garlic and onions, and their bioactive sulfur compounds and highlights research gaps.

Garlic (Allium sativum) stimulates lipopolysaccharide-induced tumor necrosis factor-alpha production from J774A.1 murine macrophages

Garlic (Allium sativum) is known to have many beneficial attributes such as antimicrobial, antiatherosclerotic, antitumorigenetic, and immunomodulatory properties. In the present study, we investigated the effects of an aqueous garlic extract on macrophage cytokine production by challenging the macrophage J774A.1 cell line with the garlic extract in the absence or presence of lipopolysaccharide (LPS) under different conditions. The effect of allicin, the major component of crushed garlic, was also investigated. Using enzyme-linked immunosorbent assay and reverse transcriptase-quantitative polymerase chain reaction, it was found that garlic and synthetic allicin greatly stimulated tumor necrosis factor-alpha (TNF-α) production in macrophages treated with LPS. The TNF-α secretion levels peaked earlier and were sustained for a longer time in cells treated with garlic and LPS compared with cells treated with LPS alone. Garlic acted in a time-dependent manner. We suggest that garlic, at least partially via its allicin component, acts downstream from LPS to stimulate macrophage TNF-α secretion.

The immunomodulation and anti-inflammatory effects of garlic organosulfur compounds in cancer chemoprevention

Garlic (Allium sativum) has been used for centuries as a prophylactic and therapeutic medicinal agent. Importantly, garlic has been suggested to have both cancer-preventive potential as well as significant enhancing effects on the immune system. While these observations are supported experimentally both in vitro and in vivo, the impact of garlic in assisting the immune system in the prevention of cancer still lacks experimental confirmation. Studies addressing the immunomodulatory effects of garlic reveal conflicting data as to pro- or anti-inflammatory responses depending on the particular experimental set-ups and the garlic preparation used (i.e. garlic extract versus chemically pure garlic compounds). Here we provide an overview of the chemistry of the major garlic organosulfur compounds, summarize the current understanding and propose a link between the immunomodulating activity of garlic and the prevention of cancer. We hypothesize that garlic rather elicits anti-inflammatory and anti-oxidative responses that aid in priming the organism towards eradication of an emerging tumor.

Diallyl disulfide inhibits proliferation and transdifferentiation of lung fibroblasts through induction of cyclooxygenase and synthesis of prostaglandin E₂

Platelet-derived growth factor-BB (PDGF-BB) and transforming growth factor-β1 (TGF-β1) are critically involved in idiopathic pulmonary fibrosis by inducing the proliferation and transdifferentiation of lung fibroblasts. In the present study, we examined the impact of diallyl disulfide (DADS), a garlic-derived compound, on such pathological conditions. DADS showed profound inhibitory effects on the PDGF-BB-induced proliferation of human and mouse lung fibroblasts. DADS also abrogated the TGF-β1-induced expression of α-smooth muscle actin, type I collagen and fibronectin. Following treatment with DADS, the expression of cyclooxygenase-2 (COX-2) and the synthesis of prostaglandin E₂ (PGE₂) were found to be markedly enhanced, which in turn led to elevated cAMP levels in lung fibroblasts. Notably, the effect of DADS was largely abolished in the presence of either COX inhibitor indomethacin or siRNA-targeting COX-2, or in the absence of the PGE₂ receptor EP2, supporting an essential role for the COX-2-PGE₂-cAMP autocrine loop. Furthermore, we demonstrated that the upregulated expression of COX-2 was a result of increased level of histone 3 acetylation at COX-2 locus in DADS-treated cells. Together, these results suggest that DADS, by inducing COX-2 expression, may have therapeutic potential in treating lung fibrosis.

Diallyl-disulfide, an organosulfur compound of garlic, attenuates airway inflammation via activation of the Nrf-2/HO-1 pathway and NF-kappaB suppression

Diallyl disulfide (DADS) is a major organosulfur compound found in garlic oil that is widely used as a flavoring agent. In this study, we evaluated the effects of DADS on airway inflammation using an ovalbumin-induced model of allergic asthma and RAW264.7 cells. DADS decreased nitric oxide production with a reduction in the levels of interleukins (IL)-1β and IL-6 in RAW264.7 cells stimulated with LPS. DADS also reduced the expression of proinflammatory proteins including inducible nitric oxide synthase (iNOS), nuclear factor (NF)-κB, and matrix metalloproteinase (MMP)-9, and it enhanced the expression of antioxidant proteins including Nrf-2 and hemeoxygenase (HO)-1. In in vivo experiments, DADS decreased the inflammatory cell count in the bronchoalveolar lavage fluid (BALF) with IL-4, IL-5, IL-13, and immunoglobulin (Ig) E. These results were consistent with the histological analysis. DADS attenuated the airway inflammation and mucus hypersecretion induced by OVA challenge. In addition, DADS induced the activation of Nrf-2 and the expression of HO-1. In contrast, DADS reduced the activation of NF-κB, iNOS and MMP-9. In conclusion, DADS reduced the airway inflammation via regulation of Nrf-2/HO-1 and NF-κB. These results suggest that DADS might represent a useful new oral therapy to treat allergic asthma.

Developing Phytocompounds from Medicinal Plants as Immunomodulators

Imbalance or malfunction of the immune systems is associated with a range of chronic diseases including autoimmune diseases, allergies, cancers and others. Various innate and adaptive immune cells that are integrated in this complex networking system may represent promising targets for developing immunotherapeutics for treating specific immune diseases. A spectrum of phytochemicals have been isolated, characterized and modified for development and use as prevention or treatment of human diseases. Many cytotoxic drugs and antibiotics have been developed from phytocompounds, but the application of traditional or new medicinal plants for use as immunomodulators in treating immune diseases is still relatively limited. In this review, a selected group of medicinal herbs, their derived crude or fractionated phytoextracts and the specific phytochemicals/phytocompounds isolated from them, as well as categorized phytocompound groups with specific chemical structures are discussed in terms of their immunomodulatory bioactivities. We also assess their potential for future development as immunomodulatory or inflammation-regulatory therapeutics or agents. New experimental approaches for evaluating the immunomodulatory activities of candidate phytomedicines are also discussed.

A polysaccharide isolated from Ecklonia cava fermented by Lactobacillus brevis inhibits the inflammatory response by suppressing the activation of nuclear factor-κB in lipopolysaccharide-induced RAW 264.7 macrophages

We previously reported that the increment of carbohydrate content in the Viscozyme(®) L (Novozyme Corp., Oklahoma City, OK, USA) extract of Lactobacillus brevis-fermented Ecklonia cava affected the inhibition of nitric oxide (NO) production and that it might be related to the polysaccharide compound. However, there is no report of anti-inflammatory effects of the polysaccharide or its biological mechanism. Here, we investigated the anti-inflammatory effects of the polysaccharide and its biological mechanism in lipopolysaccharide (LPS)-activated RAW 264.7 cells. The polysaccharide isolated from the Viscozyme extract of L. brevis-fermented E. cava (VLFEP) dose-dependently decreased LPS-stimulated NO production without cytotoxicity. Also, VLFEP significantly decreased the production of prostaglandin E(2) (PGE(2)) at the 100 μg/mL concentration. In addition, VLFEP dose-dependently decreased the protein and mRNA expressions of inducible NO synthase, whereas it slightly decreased those of cyclooxygenase 2 and only at the 100 μg/mL concentration. Moreover, VLEFP dose-dependently decreased the productions and/or mRNA expressions of tumor necrosis factor-α and interleukin-6, compared with those of LPS only-stimulated cells. In further experiments, VLFEP considerably reduced the phosphorylation and degradation of inhibitory κB as well as the translocation of nuclear transcription factor-κB (NF-κB) p65 into the nucleus, and its DNA binding was markedly induced by LPS stimulation. This study suggests that VLFEP exerts anti-inflammatory effects by down-regulating the production and expression of pro-inflammatory cytokines and mediators via inhibiting the NF-κB pathway in LPS-stimulated RAW 264.7 cells.

Effect of garlic oil on neutrophil infiltration in the small intestine of endotoxin-injected rats and its association with levels of soluble and cellular adhesion molecules

Garlic ( Allium sativum ) possesses anti-inflammatory effects. This study investigated the effects of garlic oil on endotoxin-induced neutrophil infiltration in the small intestine. Wistar rats received by gavage 10, 50, or 100 mg/kg body wt garlic oil (GO) or the vehicle (corn oil; 2 mL/kg body wt) every other day for 2 weeks before being injected with endotoxin (ip, 5 mg/kg body wt). Control rats were administered corn oil and injected with sterile saline. Blood samples for the measurement of soluble adhesion molecules were collected at various time points after injection, and all other samples were collected 18 h after injection. The 10 and 50 mg/kg doses suppressed endotoxin-induced neutrophilia, serum levels of sL-selectin and sICAM-1, cellular CD11b on neutrophils, intestinal ICAM-1 content, and neutrophil infiltration (P < 0.05). The 100 mg/kg dose significantly lowered local ICAM-1 and cellular CD11b on neutrophils (P < 0.05) but did not have a beneficial effect on neutrophil infiltration. In addition, 100 mg/kg of GO worsened the elevation of the local TNF-α level and neutrophilia. Appropriate doses of garlic oil have a preventive effect on endotoxin-induced neutrophil infiltration and damage to the small intestine.

Inflammatory signaling in skeletal muscle insulin resistance: green signal for nutritional intervention?

PURPOSE OF REVIEW

To review the evidence implying a role of inflammatory signaling pathways, specifically nuclear factor-κB and c-Jun NH2-terminal kinase, in fatty acid-induced skeletal muscle insulin resistance and to discuss the potential of dietary interventions to interfere with these processes.

RECENT FINDINGS

Fatty acids can induce skeletal muscle insulin resistance via inflammatory signaling after binding Toll-like receptors at the cell membrane of muscle cells or after accumulating as intramyocellular lipid metabolites. In both processes, activation of intracellular inflammatory signaling is involved. The majority of literature addressing the causality of muscle nuclear factor-κB activation in skeletal muscle insulin resistance suggests that insulin resistance does not require muscle nuclear factor-κB activation. Recently, strong evidence was given that c-Jun NH2-terminal kinase signaling is an important inflammatory pathway involved in skeletal muscle insulin resistance. Furthermore, it is well established that proinflammatory cytokines originating from the enlarged adipose tissue or from activated adipose tissue macrophages can cause muscle insulin resistance. Recently, also macrophages resided in the muscle have been proposed to play an important role in muscle insulin resistance. Because of their anti-inflammatory characteristics, several dietary components like polyphenols may be interesting candidates for manipulating skeletal muscle insulin resistance.

SUMMARY

Several dietary components, like polyphenols, have been reported to interfere with inflammatory signaling. To test whether these compounds can be used to prevent or reverse insulin resistance, well controlled human intervention studies have to be designed.

Allylmethylsulfide Down-Regulates X-Ray Irradiation-Induced Nuclear Factor-kappaB Signaling in C57/BL6 Mouse Kidney

Allylmethylsulfide (AMS), a volatile organosulfur derivative from garlic, has been shown to have radioprotective effects in radiation-challenged cell and animal models, but the mechanism of radioprotection is not well understood. To determine the mechanism of radioprotection in an in vivo model, we first verified the antioxidant capacity of AMS using 2,2'-azobis(2-amidinopropane) dihydrochloride-induced human embryonic kidney 293T cells by measuring reactive oxygen species generation, reduced glutathione, protein tyrosine kinase/protein tyrosine phosphatase balance, and nuclear factor-kappaB (NF-kappaB) protein levels. We then investigated the protective effects of AMS (55 and 275 micromol/kg, intraperitoneal treatment) on 15 Gy X-ray-irradiated mouse kidney. The results showed that AMS decreased the free radical-induced lipid peroxidation in mice exposed to X-rays. Moreover, the antioxidative AMS suppressed the activation of NF-kappaB and its dependent genes such as vascular cell adhesion molecule-1, inducible nitric oxide synthase, and cyclooxygenase-2 through inhibition of IkappaBalpha phosphorylation and activation of IkappaB kinase alpha/beta and mitogen-activated protein kinases (MAPKs). Based on these results, AMS may be a useful radioprotective agent by down-regulating the MAPKs and NF-kappaB signaling pathway that can be induced via X-ray irradiation.

The effect of garlic consumption on Th1/Th2 cytokines in phytohemagglutinin (PHA) activated rat spleen lymphocytes

The balance and regulation of T helper 1 (Th1) and Th2-type cytokines are important in the effective immune response to different diseases. To clarify the effect of garlic (Allium sativum L.) consumption on the Th1/Th2 balance, the secretion of gamma interferon (IFN-gamma) and interleukin-4 (IL-4), as two prototypes of Th1/Th2 cytokines, were compared in serum and supernatant of in vitro phytohemagglutinin activated rat spleen lymphocytes. Thirty male rats were divided equally into two groups. The treatment group received garlic solution in water (600 mg/kg/4 mL) and controls received distilled water by gavage. After 1 month, serum and supernatant of PHA activated spleen lymphocytes were analysed for IFN-gamma and IL-4 by the enzyme-linked immunosorbent assay test and thymus and spleen weights were measured. The garlic treatment group showed significantly decreased production of IFN-gamma from 101.73 +/- 4.62 to 74.64 +/- 4.64 pg/mL and significantly increased IL-4 production from 26.75 +/- 3.35 to 83.92 +/- 6.56 pg/mL (p < 0.001) in the supernatant of PHA induced spleen lymphocytes. The serum level of these cytokines was undetectable. The mean weight of thymuses in the garlic fed animals was significantly reduced from 0.456 +/- 0.016 to 0.368 +/- 0.023 g compared with the control group (p < 0.005). There were no significant differences between the spleen weights in the two groups. In conclusion, oral garlic treatment may favor a Th2 or humoral immune response.

Nitric oxide as a target of complementary and alternative medicines to prevent and treat inflammation and cancer

Nitric oxide (NO) and associated reactive nitrogen species (RNS) are involved in many physiological functions. There has been an ongoing debate to whether RNS can inhibit or perpetuate chronic inflammation and associated carcinogenesis. Although the final outcome depends on the genetic make-up of its target, the surrounding microenvironment, the activity and localization of nitric oxide synthase (NOS) isoforms, and overall levels of NO/RNS, evidence is accumulating that in general, RNS drive inflammation and cancers associated with inflammation. To this end, many complementary and alternative medicines (CAMs) that work in chemoprevention associated with chronic inflammation, are inhibitors of excessive NO observed in inflammatory conditions. Here, we review recent literature outlining a role of NO/RNS in chronic inflammation and cancer, and point toward NO as one of several targets for the success of CAMs in treating chronic inflammation and cancer associated with this inflammation.

Oxidative stress and male infertility--a clinical perspective

Oxidative stress occurs when the production of potentially destructive reactive oxygen species (ROS) exceeds the bodies own natural antioxidant defenses, resulting in cellular damage. Oxidative stress is a common pathology seen in approximately half of all infertile men. ROS, defined as including oxygen ions, free radicals and peroxides are generated by sperm and seminal leukocytes within semen and produce infertility by two key mechanisms. First, they damage the sperm membrane, decreasing sperm motility and its ability to fuse with the oocyte. Second, ROS can alter the sperm DNA, resulting in the passage of defective paternal DNA on to the conceptus. This review will provide an overview of oxidative biochemistry related to sperm health and will identify which men are most at risk of oxidative infertility. Finally, the review will outline methods available for diagnosing oxidative stress and the various treatments available.

Cinnamaldehyde inhibits pro-inflammatory cytokines secretion from monocytes/macrophages through suppression of intracellular signaling

We investigated the in vitro anti-inflammatory effects of Cinnamaldehyde, a cytokine production inhibitor isolated from an essential oil produced from the leaves of Cinnamomum osmophloeum Kaneh, and its mechanism of action. Although Cinnamaldehyde has been reported to have contact sensitizing properties at high concentration (mM), we found that low concentration of Cinnamaldehyde (muM) inhibited the secretion of interleukin-1beta and tumor necrosis factor alpha within lipopolysaccharide (LPS) or lipoteichoic acid (LTA) stimulated murine J774A.1 macrophages. Cinnamaldehyde also suppressed the production of these cytokines from LPS stimulated human blood monocytes derived primary macrophages and human THP-1 monocytes. Furthermore, Cinnamaldehyde also inhibited the production of prointerleukin-1beta within LPS or LTA stimulated human THP-1 monocytes. Reactive oxygen species release from LPS stimulated J774A.1 macrophages was reduced by Cinnamaldehyde. The phosphorylation of extracellular signal-regulated kinase 1/2 and c-Jun N-terminal kinase 1/2 induced by LPS was also inhibited by Cinnamaldehyde; however, Cinnamaldehyde neither antagonize the binding of LPS to the cells nor alter the cell surface expression of toll-like receptor 4 and CD14. In addition, we also noted that Cinnamaldehyde appeared to elicit no cytotoxic effect upon J774A.1 macrophages under our experimental conditions, although Cinnamaldehyde reduced J774A.1 macrophages proliferation as analysed by MTT assay. Our current results have demonstrated the anti-oxidation and anti-inflammatory properties of Cinnamaldehyde that could provide the possibility for Cinnamaldehyde's future pharmaceutical application in the realm of immuno-modulation.