Prevention of collagen-induced arthritis in mice by a polyphenolic fraction from green tea

Inhibition of autoantigen expression by (-)-epigallocatechin-3-gallate (the major constituent of green tea) in normal human cells

Autoimmune disorders, characterized by inflammation and apoptosis of target cells leading to tissue destruction, are mediated in part by autoantibodies against normal cellular components (autoantigens) that may be overexpressed. For example, antibodies against the autoantigens SS-A/Ro and SS-B/La are primary markers for systemic lupus erythematosus and Sjögren's syndrome. Recently, studies in animals demonstrated that green tea consumption may reduce the severity of some autoimmune disorders, but the mechanism is unclear. Herein, we sought to determine whether the most abundant green tea polyphenol, (-)-epigallocatechin-3-gallate (EGCG), affects autoantigen expression in human cells. Cultures of pooled normal human primary epidermal keratinocytes and of an immortalized human salivary acinar cell line were incubated with 100 microM EGCG (a physiologically achievable level for topical application or oral administration) for various time periods and then analyzed by cDNA microarray analysis, reverse transcription-polymerase chain reaction, and Western blotting for expression of several major autoantigen candidates. EGCG inhibited the transcription and translation of major autoantigens, including SS-B/La, SS-A/Ro, coilin, DNA topoisomerase I, and alpha-fodrin. These findings, taken together with green tea's anti-inflammatory and antiapoptotic effects, suggest that green tea polyphenols could serve as an important component in novel approaches to combat autoimmune disorders in humans.

The apoptotic effect of green tea (-)-epigallocatechin gallate on 3T3-L1 preadipocytes depends on the Cdk2 pathway

This study was designed to investigate the effect of green tea catechins, especially (-)-epigallocatechin gallate (EGCG), on the apoptosis of 3T3-L1 preadipocytes. Preadipocyte apoptosis as indicated by formation of DNA fragments was induced by EGCG in dose-dependent manners. While EGCG was demonstrated to decrease Cdk2 expression and activity and increase caspase-3 activity, overexpression of Cdk2 and treatment with the caspase-3 inhibitor respectively prevented preadipocytes from induction of DNA fragmentation and caspase-3 activity by doses of 100-400 muM of EGCG. This suggests the Cdk2- and caspase-3-dependent apoptotic effects of EGCG. Moreover, EGCG was more effective than EC, ECG, and EGC in changing the apoptotic signals. Results of this study may relate to the mechanism by which EGCG modulates body weight.

Disease-modifying therapies for osteoarthritis : current status

Osteoarthritis, the most common form of arthritis, is a debilitating progressive disease principally affecting the elderly. Osteoarthritis therapy has evolved in the past few decades from symptomatic treatment to possible disease-modifying solutions. In this paper, the pathophysiology of osteoarthritis is first reviewed, including an examination of the mechanisms underlying osteoarthritis and discussions of the roles of cartilage, synovial fluid and subchondral bone. The remainder of the paper discusses therapeutic approaches in current use and those in development, with special attention given to pharmacological treatments. Current approaches to treating osteoarthritis--i.e. medications; nonpharmacological modalities, such as physical therapy, exercise, weight management and orthotics; and (as a last resort) surgery--focus on reducing pain and improving (or at least maintaining) mobility. Drugs currently used to treat osteoarthritis fall into several categories: analgesics, NSAIDs, cyclo-oxygenase-2 (COX-2) inhibitors, corticosteroids, viscosupplementation, and symptomatic slow-acting drugs ('nutraceuticals'). The analgesics (paracetamol [acetaminophen] and opiates) have demonstrated less symptomatic efficacy than NSAIDs, while the latter have displayed mixed results in terms of joint space narrowing. COX-2 inhibitors have been demonstrated to be equal to or superior to NSAIDs in effectiveness. However, once considered a safer alternative, COX-2 inhibitors have become the subject of intense scrutiny since recent clinical evidence has cast suspicion on their cardiovascular safety profile. Injectable therapies, such as corticosteroids and viscosupplementation have elicited favorable short-term response but no long-term structural modification. On the other hand, the slow-acting drugs, especially chondroitin and glucosamine sulfate, have shown promising results. Also reviewed are other established and experimental therapies that seek to modify and/or even reverse the course of osteoarthritis. These include such medications as colchicine, bisphosphonates and hormones; dietary therapeutics, such as ginger extract and green tea; and such truly experimental treatments as matrix metalloproteinase inhibitors, cytokines, nitric oxide, growth factors and gene therapy. Osteoarthritis continues to be a difficult disorder to treat, as there is no cure as such and current treatments focus mainly on relieving pain and maintaining joint function. The search nevertheless continues for management regimens that can slow, alter or reverse the degenerative processes of osteoarthritis.

Searching for the role and the most suitable biomarkers of oxidative stress in Alzheimer's disease and in other neurodegenerative diseases

The contribution of oxidative stress to neurodegeneration is not peculiar of a specific neurodegenerative disease, oxidative stress has been found implicated in a number of neurodegenerative disorders among which Alzheimer's disease (AD), Parkinson's disease (PD), amyotrophic lateral sclerosis (ALS). Even increasing are studies dealing with the search for peripheral biomarkers of oxidative stress in biological fluids or even in peripheral tissues themselves such as fibroblasts or blood cells. The application of the modified version of the comet assay for the detection of oxidised purines and pyrimidines in peripheral blood leukocytes results particularly useful if the study requires repeated blood drawn from the same individual, for instance if a clinical trial is performed with a preventive therapy. Likely damage occurs to every category of biological macromolecules and we consider, in the context of neurodegenerative diseases, particularly critical the proteic level. The identification of subjects at risk to develop AD or with pre-pathogenic conditions, the possibility to use "a battery of assays" for the detection of oxidative damage at peripheral level, together with recent advances in brain imaging, will allow to better address studies aimed not only to therapeutic purposes but also mainly to primary prevention.

Nutraceutical Therapies for Degenerative Joint Diseases: A Critical Review

There is growing recognition of the importance of nutritional factors in the maintenance of bone and joint health, and that nutritional imbalance combined with endocrine abnormalities may be involved in the pathogenesis of osteoarthritis (OA) and osteochondritis dissecans (OCD). Despite this, dietary programs have played a secondary role in the management of these connective tissue disorders. Articular cartilage is critically dependent upon the regular provision of nutrients (glucose and amino acids), vitamins (particularly vitamin C), and essential trace elements (zinc, magnesium, and copper). Therefore, dietary supplementation programs and nutraceuticals used in conjunction with non-steroidal, anti-inflammatory drugs (NSAIDs) may offer significant benefits to patients with joint disorders, such as OA and OCD. This article examines the available clinical evidence for the efficacy of nutraceuticals, antioxidant vitamin C, polyphenols, essential fatty acids, and mineral cofactors in the treatment of OA and related joint disorders in humans and veterinary species. This article also attempts to clarify the current state of knowledge. It also highlights the need for additional targeted research to elucidate the changes in nutritional status and potential alterations to the expression of plasma membrane transport systems in synovial structures in pathophysiological states, so that current therapy and future treatments may be better focused.

Future treatment of osteoarthritis

Osteoarthritis represents an advanced stage of disease progression caused in part by injury, loss of cartilage structure and function, and an imbalance in inflammatory and noninflammatory pathways. The burden of this disease will increase in direct proportion to the increase in the older adult population. Research on current and experimental treatment protocols are reviewed, including the effect of hyaluronic acid in both in vitro and in vivo studies, autologous chondrocyte and osteochondral plug implantation, and gene therapy. Disease-modifying osteoarthritis drugs and in vivo studies of glucosamine and chondroitin sulfate are reviewed.

Antimitogenic effect of green tea (-)-epigallocatechin gallate on 3T3-L1 preadipocytes depends on the ERK and Cdk2 pathways

Green tea catechins, especially (-)-epigallocatechin gallate (EGCG), have been proposed as a chemopreventative for obesity, diabetes, cancer, and cardiovascular diseases. However, relatively little is known about the mechanism of the action of EGCG on fat cell function. This study was designed to investigate the pathways of EGCG's modulation of the mitogenesis of 3T3-L1 preadipocytes. Preadipocyte proliferation as indicated by an increased number of cells and greater incorporation of bromodeoxyuridine (BrdU) was inhibited by EGCG in dose-, time-, and growth phase-dependent manners. Also, EGCG dose and time dependently decreased levels of phospho-ERK1/2, Cdk2, and cyclin D(1) proteins, reduced Cdk2 activity, and increased levels of G(0)/G(1) growth arrest, p21(waf/cip), and p27(kip1), but not p18(ink), proteins and their associations to Cdk2. However, neither MEK1, ERK1/2, p38 MAPK, phospho-p38, JNK, nor phospho-JNK was changed. Increased phospho-ERK1/2 content and Cdk2 activity, respectively, via the transfection of MEK1 and Cdk2 cDNA into preadipocytes prevented EGCG from reducing cell numbers. These data demonstrate the ERK- and Cdk2-dependent antimitogenic effects of EGCG. Moreover, EGCG was more effective than epicatechin, epicatechin gallate, and epigallocatechin in changing the mitogenic signals. The signal of EGCG in reducing growth of 3T3-L1 preadipocytes differed from that of 3T3 fibroblasts. Results of this study may relate to the mechanism by which EGCG modulates body weight.

Identification of flavonoids using liquid chromatography with electrospray ionization and ion trap tandem mass spectrometry with an MS/MS library

Searchable MS/MS spectra libraries, constructed using the results of liquid chromatography coupled with electrospray ionization (ESI) tandem mass spectrometry (LC/MS/MS) with data-dependent acquisition on an ion trap mass spectrometer, are presented with regard to the identification and confirmation of a variety of closely related flavonoids in a set of biological samples. Flavonoids were found to exhibit a maximum amount of structurally specific MS/MS spectra at 45% of normalized collision energy on the instrument used, without wideband activation. These MS/MS spectra were then searched automatically against a 297-substance MS/MS library that contains many previously acquired spectra of standard flavonoids. The possible applications of this powerful technique to biological samples are also discussed. Daidzein and genistein were identified through the MS/MS spectra library while searching through LC/MS/MS data for plant and microbial extracts. Moreover, these compounds proved completely distinguishable from other flavonoids of closely related structures in the MS/MS spectra library, using the NIST MS search program. The applicability of the library-searchable spectra at low concentrations was demonstrated by successful identification of daidzein and genistein at 0.05 and 0.5 microg/mL, respectively.

Inhibitory effects of epicatechin on interleukin-1beta-induced inducible nitric oxide synthase expression in RINm5F cells and rat pancreatic islets by down-regulation of NF-kappaB activation

Cytokines that are released by infiltrating inflammatory cells around the pancreatic islets are involved in the pathogenesis of type 1 diabetes mellitus. Specifically, interleukin-1beta (IL-1beta) stimulates inducible nitric oxide synthase (iNOS) expression and nitric oxide overproduction, leading to the beta-cell damage. In activating this pathway, nuclear factor-kappaB (NF-kappaB) plays a crucial role, and many of the IL-1beta-sensitive genes contain NF-kappaB binding sites in their promoter regions. We have recently shown that epicatechin, which is a flavonoid, had a protective effect on pancreatic beta-cells in both streptozotocin-treated rats and islets. In the present study, the effects of epicatechin on IL-1beta-induced beta-cell damage were examined. RINm5F cells and islets were pretreated with epicatechin and next incubated with IL-1beta. The released nitrite, iNOS protein and mRNA expression levels were then measured. IkappaBalpha protein, nuclear translocation of NF-kappaB, and NF-kappaB DNA binding activity were also determined. Following the transient transfection of an iNOS promoter into the cells, the iNOS promoter activity was measured. ATP- or D-glucose-induced insulin release was measured in RINm5F cells and islets, respectively. Epicatechin significantly reduced IL-1beta-induced nitrite production, iNOS protein and mRNA expressions, and it also inhibited IL-1beta-induced IkappaBalpha protein degradation, NF-kappaB activation, and iNOS promoter activity. Epicatechin partly restored the IL-1beta-induced inhibition of insulin release. These results suggest that epicatechin inhibits the IL-1beta-induced iNOS expression by down-regulating NF-kappaB activation, and protecting beta-cells from IL-1beta.

Anti-arthritic effect and subacute toxicological evaluation of Baccharis genistelloides aqueous extract

This work studies the potential subacute toxicological effects of the aqueous extract of Baccharis genistelloides (AEBg) and demonstrates a new anti-arthritic therapeutic effect. The treatment of the collagen-induced arthritis (CIA) group with 4.2 mg/kg AEBg induced an important decrease (75%) in CIA severity in all animals, while the 42 mg/kg dose treated only 50% of animals. After AEBg treatment, no significant differences were observed in body weight, aspect, color and relative weight of liver, kidneys, thymus or lungs between CIA groups. CIA and healthy AEBg groups treated with both doses did not show genotoxic effects to liver and kidney cells by the Comet assay, compared to its own control group. The augmented AST in the CIA group, compared to healthy control one was regularized by the AEBg treatment with 4.2 mg/kg but not with 42 mg/kg. No other significant difference was found on serum biochemical parameters, as well as on spontaneous or stimulated lymphocyte proliferation between CIA groups. The treatment of healthy animals with AEBg 4.2 mg/kg did not change the aspect, color or relative weight of kidneys, liver or lungs but reduced the body weight, the thymus and popliteal lymph node (PLN) relative weight and serum glucose and triglyceride levels. Concluding, our results indicate an anti-arthritic effects of AEBg without liver and kidney subacute toxicity and hypoglycemic and hypotriglyceridemic actions on healthy animals.

Inhibitory effects of proanthocyanidins from Ribes nigrum leaves on carrageenin acute inflammatory reactions induced in rats

Background

The anti-inflammatory effects of proanthocyanidins (PACs), isolated from blackcurrant (Ribes nigrum L.) leaves, were analysed using carrageenin-induced paw oedema and carrageenin-induced pleurisy in rats.

Results

Pretreatment of the animals with PACs (10, 30, 60 and 100 mg/kg, i.p.) reduced paw oedema induced by carrageenin in a dose and time-dependent manner. PACs also inhibited dose-dependently carrageenin-induced pleurisy in rats. They reduced (A) lung injury, (B) pleural exudate formation, (C) polymorphonuclear cell infiltration, (D) pleural exudate levels of TNF-α, IL-1β and CINC-1 but did not affect IL-6 and IL-10 levels. They reduced (E) pleural exudate levels of nitrite/nitrate (NOx). In indomethacin treated rats, the volume of pleural exudate was low, its content in leukocytes and its contents in TNF-α, IL-1β, IL-6 and IL-10 but not in NOx were reduced. These data suggest that the anti-inflammatory properties of PACs are achieved through a different pattern from those of indomethacin.

Conclusion

These results suggest that the main mechanism of the anti-inflammatory effect of PACs mainly lies in an interference with the migration of the leukocytes. Moreover, PACs inhibited in vivo nitric oxide release.

Green Tea Epigallocatechin-3-Gallate Mediates T Cellular NF-κB Inhibition and Exerts Neuroprotection in Autoimmune Encephalomyelitis

Recent studies in multiple sclerosis and its animal model, experimental autoimmune encephalomyelitis (EAE), point to the fact that even in the early phase of inflammation, neuronal pathology plays a pivotal role in the sustained disability of affected individuals. We show that the major green tea constituent, (-)-epigallocatechin-3-gallate (EGCG), dramatically suppresses EAE induced by proteolipid protein 139-151. EGCG reduced clinical severity when given at initiation or after the onset of EAE by both limiting brain inflammation and reducing neuronal damage. In orally treated mice, we found abrogated proliferation and TNF-alpha production of encephalitogenic T cells. In human myelin-specific CD4+ T cells, cell cycle arrest was induced, down-regulating the cyclin-dependent kinase 4. Interference with both T cell growth and effector function was mediated by blockade of the catalytic activities of the 20S/26S proteasome complex, resulting in intracellular accumulation of IkappaB-alpha and subsequent inhibition of NF-kappaB activation. Because its structure implicates additional antioxidative properties, EGCG was capable of protecting against neuronal injury in living brain tissue induced by N-methyl-D-aspartate or TRAIL and of directly blocking the formation of neurotoxic reactive oxygen species in neurons. Thus, a natural green tea constituent may open up a new therapeutic avenue for young disabled adults with inflammatory brain disease by combining, on one hand, anti-inflammatory and, on the other hand, neuroprotective capacities.

Oxidation in rheumatoid arthritis

Oxygen metabolism has an important role in the pathogenesis of rheumatoid arthritis. Reactive oxygen species (ROS) produced in the course of cellular oxidative phosphorylation, and by activated phagocytic cells during oxidative bursts, exceed the physiological buffering capacity and result in oxidative stress. The excessive production of ROS can damage protein, lipids, nucleic acids, and matrix components. They also serve as important intracellular signaling molecules that amplify the synovial inflammatory-proliferative response. Repetitive cycles of hypoxia and reoxygenation associated with changes in synovial perfusion are postulated to activate hypoxia-inducible factor-1alpha and nuclear factor-kappaB, two key transcription factors that are regulated by changes in cellular oxygenation and cytokine stimulation, and that in turn orchestrate the expression of a spectrum of genes critical to the persistence of synovitis. An understanding of the complex interactions involved in these pathways might allow the development of novel therapeutic strategies for rheumatoid arthritis.

Catechin polyphenols: neurodegeneration and neuroprotection in neurodegenerative diseases

Neurodegeneration in Parkinson's, Alzheimer's, and other neurodegenerative diseases seems to be multifactorial, in that a complex set of toxic reactions including inflammation, glutamatergic neurotoxicity, increases in iron and nitric oxide, depletion of endogenous antioxidants, reduced expression of trophic factors, dysfunction of the ubiquitin-proteasome system, and expression of proapoptotic proteins leads to the demise of neurons. Thus, the fundamental objective in neurodegeneration and neuroprotection research is to determine which of these factors constitutes the primary event, the sequence in which these events occur, and whether they act in concurrence in the pathogenic process. This has led to the current notion that drugs directed against a single target will be ineffective and rather a single drug or cocktail of drugs with pluripharmacological properties may be more suitable. Green tea catechin polyphenols, formerly thought to be simple radical scavengers, are now considered to invoke a spectrum of cellular mechanisms of action related to their neuroprotective activity. These include pharmacological activities like iron chelation, scavenging of radicals, activation of survival genes and cell signaling pathways, and regulation of mitochondrial function and possibly of the ubiquitin-proteasome system. As a consequence these compounds are receiving significant attention as therapeutic cytoprotective agents for the treatment of neurodegenerative and other diseases.

Antioxidants of the beverage tea in promotion of human health

Tea that contains many antioxidants is a pleasant and safe drink that is enjoyed by people across the globe. Tea leaves are manufactured as black, green, or oolong. Black tea represents approximately 78% of total consumed tea in the world, whereas green tea accounts for approximately 20% of tea consumed. The concept of "use of tea for promotion of human health and prevention and cure of diseases" has become a subject of intense research in the last decade. Diseases for which tea drinkers appear to have lower risk are simple infections, like bacterial and viral, to chronic debilitating diseases, including cancer, coronary heart disease, stroke, and osteoporosis. Initial work on green tea suggested that it possesses human health-promoting effects. In recent years, the research efforts have been expanded to black tea as well. Research conducted in recent years reveals that both black and green tea have very similar beneficial attributes in lowering the risk of many human diseases, including several types of cancer and heart diseases. For cancer prevention, evidence is so overwhelming that the Chemoprevention Branch of the National Cancer Institute has initiated a plan for developing tea compounds as cancer-chemopreventive agents in human trials. Thus, modern medical research is confirming the ancient wisdom that therapy of many diseases may reside in an inexpensive beverage in a "teapot."

Cell signaling pathways in the neuroprotective actions of the green tea polyphenol (-)-epigallocatechin-3-gallate: implications for neurodegenerative diseases

Accumulating evidence supports the hypothesis that brain iron misregulation and oxidative stress (OS), resulting in reactive oxygen species (ROS) generation from H2O2 and inflammatory processes, trigger a cascade of events leading to apoptotic/necrotic cell death in neurodegenerative disorders, such as Parkinson's (PD), Alzheimer's (AD) and Huntington's diseases, and amyotrophic lateral sclerosis (ALS). Thus, novel therapeutic approaches aimed at neutralization of OS-induced neurotoxicity, support the application of ROS scavengers, transition metals (e.g. iron and copper) chelators and non-vitamin natural antioxidant polyphenols, in monotherapy, or as part of antioxidant cocktail formulation for these diseases. Both experimental and epidemiological evidence demonstrate that flavonoid polyphenols, particularly from green tea and blueberries, improve age-related cognitive decline and are neuroprotective in models of PD, AD and cerebral ischemia/reperfusion injuries. However, recent studies indicate that the radical scavenger property of green tea polyphenols is unlikely to be the sole explanation for their neuroprotective capacity and in fact, a wide spectrum of cellular signaling events may well account for their biological actions. In this article, the currently established mechanisms involved in the beneficial health action and emerging studies concerning the putative novel molecular neuroprotective activity of green tea and its major polyphenol (-)-epigallocatechin-3-gallate (EGCG), will be reviewed and discussed.

Effects of green tea polyphenols on murine transplant-reactive T cell immunity

Green tea polyphenols (GrTP), the active ingredient of green tea, may have immunosuppressive properties, but whether and how GrTP affect transplant-reactive T cells is unknown. To address this, we tested the effects of GrTP on in vitro and in vivo transplant-reactive T cell immunity. GrTP inhibited IFNgamma secretion by cultured monoclonal T cells and by alloreactive T cells in mixed lymphocyte reactions. Oral GrTP significantly prolonged minor antigen-disparate skin graft survival and decreased the frequency of donor-reactive interferon gamma-producing T cells in recipient secondary lymphoid organs compared to controls. In contrast to other hypothesized actions, oral GrTP did not alter dendritic cell trafficking to lymph nodes or affect metalloproteinase activity in the graft. This is the first report of an immunosuppressive effect of GrTP on transplant-reactive T cell immunity. The results suggest that oral intake of green tea could act as an adjunctive therapy for prevention of transplant rejection in humans.

Neprilysin levels in plasma and synovial fluid of juvenile idiopathic arthritis patients

OBJECTIVE

Neprilysin (neutral endopeptidase, 3:4:24:11, CD10) (NEP) is a Zn metallopeptidase linked to controlling inflammation through the degradation of neuropeptides involved in neurogenic inflammation of chronic rheumatic diseases. The aim of our study was to evaluate circulating activity and cellular expression of NEP in the plasma of 58 children with juvenile idiopathic arthritis (JIA) and 52 controls. In 20 subjects requiring local steroid injection, NEP was measured in synovial fluid.

METHODS

Plasma and synovial NEP were evaluated using a fluorimetric technique. Neprilysin, expressed as the antigen CD10, was determined on circulating and synovial fluid cells as mean fluorescence intensity (MFI) and as percentage of positive cells by two-color immunofluorescence.

RESULTS

Circulating NEP levels were lower in JIA patients than in controls (42.0+/-16.6 vs 76.5+/-24 pmol/ml per min, P<0.001), while synovial fluid NEP values were higher than circulating levels (241.4+/-86.2 vs 40+/-15.3 pmol/ml per min, P<0.001). In monocytes, the percentage of CD10-positive circulating cells and the MFI in JIA were lower than in controls (11.6+/-5.2% vs 41.4+/-13%, P<0.001 and 18.1+/-7.5 vs 31.2+/-5.4, P<0.05, respectively). On synovial monocytes, the percentage of CD10-positive cells and the MFI were higher than on circulating monocytes (35.2+/-14.6% vs 9.1+/-2.4%, P<0.001 and 66.4+/-5.4 vs 22.8+/-14.7, P<0.001, respectively).

CONCLUSIONS

The downregulation of CD10 expression in monocytes and the reduction in NEP activity may be linked to the enzyme's role in the control of peptides involved in the inflammation. The increased levels of NEP, MFI, and CD10-positive monocytes in synovial fluid, even though in plasma, might reflect a reactive effort to control synovial proliferation.

Nutritional and botanical modulation of the inflammatory cascade--eicosanoids, cyclooxygenases, and lipoxygenases--as an adjunct in cancer therapy

Emerging on the horizon in cancer therapy is an expansion of the scope of treatment beyond cytotoxic approaches to include molecular management of cancer physiopathology. The goal in these integrative approaches, which extends beyond eradicating the affected cells, is to control the cancer phenotype. One key new approach appears to be modulation of the inflammatory cascade, as research is expanding that links cancer initiation, promotion, progression, angiogenesis, and metastasis to inflammatory events. This article presents a literature review of the emerging relationship between neoplasia and inflammatory eicosanoids (PGE2 and related prostaglandins), with a focus on how inhibition of their synthesizing oxidases, particularly cyclooxygenase (COX), offers anticancer actions in vitro and in vivo. Although a majority of this research emphasizes the pharmaceutical applications of nonsteroidal anti-inflammatory drugs and selective COX-2 inhibitors, these agents fail to address alternate pathways available for the synthesis of proinflammatory eicosanoids. Evidence is presented that suggests the inhibition of lipoxygenase and its by-products-LTB4, 5-HETE, and 12-HETE-represents an overlooked but crucial component in complementary cancer therapies. Based on the hypothesis that natural agents capable of modulating both lipoxygenase and COX may advance the efficacy of cancer therapy, an overview and discussion is presented of dietary modifications and selected nutritional and botanical agents (notably, omega-3 fatty acids, antioxidants, boswellia, bromelain, curcumin, and quercetin) that favorably influence eicosanoid production.

Biological basis for the benefit of nutraceutical supplementation in arthritis

Arthritis is a common disease in which the end-point results in joint replacement surgery. This article reviews the use of nutraceuticals as alternative treatments for pathological manifestations of arthritic disease. The efficacy of fish oils (e.g. cod liver oil) in the diet has been demonstrated in several clinical trials, animal feeding experiments and in vitro models that mimic cartilage destruction in arthritic disease. In addition, there is some evidence for beneficial effects of other nutraceuticals, such as green tea, herbal extracts, chondroitin sulphate and glucosamine. However, in most cases, there is little scientific evidence at the cellular and molecular levels to explain their mechanisms of action.

Green tea inhibits human inducible nitric-oxide synthase expression by down-regulating signal transducer and activator of transcription-1alpha activation

Green tea has been reported to show anti-inflammatory properties because of its inhibitory effects on the expression of several pro-inflammatory genes. Because the inducible nitricoxide synthase (iNOS) plays an important role in chronic inflammatory diseases, we have focused our attention on the regulation of iNOS expression by green tea in two different human epithelial cell lines, alveolar A549/8 and colon DLD-1 cells. With the use of electrophoretic mobility shift assays, we found a green tea-mediated down-regulation of the DNA binding activity of the transcription factor signal transducer and activator of transcription-1alpha (STAT-1alpha), but not of nuclear factor-kappaB. This down-regulation of the STAT-1alpha DNA binding was shown to result from reduced tyrosine phosphorylation of the STAT-1alpha protein and not from antioxidative effects of the green tea extract. Green tea extract inhibited human iNOS expression in a concentration-dependent manner, quantified in terms of iNOS mRNA, iNOS protein, and nitric oxide production in both cell lines. This inhibitory effect of green tea resulted from transcriptional inhibition as shown in reporter gene experiments. These data suggest that green tea extracts may be promising at least as an auxiliary anti-inflammatory principle in chronic inflammatory diseases.

Pathophysiological mechanisms in osteoarthritis lead to novel therapeutic strategies

Osteoarthritis (OA) is a debilitating, progressive disease of diarthrodial joints associated with aging. At the molecular level, OA is characterized by an imbalance between anabolic (i.e. extracellular matrix biosynthesis) and catabolic (i.e. extracellular matrix degradation) pathways in which articular cartilage is the principal site of tissue injury responses. The pathophysiology of OA also involves the synovium in that 'nonclassical' inflammatory synovial processes contribute to OA progression. Chondrocytes are critical to the OA process in that the progression of OA can be judged by the vitality of chondrocytes and their ability to resist apoptosis. Growth factors exemplified by insulin-like growth factor-1, its binding proteins and transforming growth factor-beta contribute to anabolic pathways including compensatory biosynthesis of extracellular matrix proteins. Catabolic pathways are altered by cytokine genes such as interleukin-1 (IL-1) and tumor necrosis factor-alpha (TNF-alpha) which are upregulated in OA. In addition, IL-1 and TNF-alpha downregulate extracellular matrix protein biosynthesis while concomitantly upregulating matrix metalloproteinase (MMP) gene expression. When MMPs are activated, cartilage extracellular matrix degradation ensues apparently because levels of endogenous cartilage MMP inhibitors cannot regulate MMP activity. Therapeutic strategies designed to modulate the imbalance between anabolic and catabolic pathways in OA may include neutralizing cytokine activity or MMP gene expression or inhibiting signaling pathways which result in apoptosis dependent on mature caspase activity or mitogen-activated protein kinase (MAPK) activity. MAPK activity appears critical for regulating chondrocyte and synoviocyte apoptosis and MMP genes.

Epigallocatechin-3-gallate, constituent of green tea, suppresses the LPS-induced phenotypic and functional maturation of murine dendritic cells through inhibition of mitogen-activated protein kinases and NF-κB

The effects of epigallocatechin-3-gallate (EGCG) on dendritic cells (DC) maturation were investigated. EGCG, in a dose-dependent manner, profoundly inhibited CD80, CD86, and MHC class I and II expression on bone marrow-derived murine myeloid DC. EGCG restored the decreased dextran-FITC uptake and inhibited enhanced IL-12 production by LPS-treated DC. EGCG-treated DC were poor stimulators of nai;ve allogeneic T-cell proliferation and reduced levels of IL-2 production in responding T cells. EGCG-pretreated DC inhibited LPS-induced MAPKs, such as ERK1/2, p38, JNK, and NF-kappaB p65 translocation. Therefore, the molecular mechanisms by which EGCG antagonized LPS-induced DC maturation appeared to involve the inhibition of MAPK and NF-kappaB activation. These novel findings provide new insight into the immunopharmacological role of EGCG and suggest a novel approach to the manipulation of DC for therapeutic application of autoimmune and allergic diseases.

Neuroprotective strategies in Parkinson's disease : an update on progress

In spite of the extensive studies performed on postmortem substantia nigra from Parkinson's disease patients, the aetiology of the disease has not yet been established. Nevertheless, these studies have demonstrated that, at the time of death, a cascade of events had been initiated that may contribute to the demise of the melanin-containing nigro-striatal dopamine neurons. These events include increased levels of iron and monoamine oxidase (MAO)-B activity, oxidative stress, inflammatory processes, glutamatergic excitotoxicity, nitric oxide synthesis, abnormal protein folding and aggregation, reduced expression of trophic factors, depletion of endogenous antioxidants such as reduced glutathione, and altered calcium homeostasis. To a large extent, the 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine (MPTP) and 6-hydroxydopamine (6-OHDA) animal models of Parkinson's disease confirm these findings. Furthermore, neuroprotection can be afforded in these models with iron chelators, radical scavenger antioxidants, MAO-B inhibitors, glutamate antagonists, nitric oxide synthase inhibitors, calcium channel antagonists and trophic factors. Despite the success obtained with animal models, clinical neuroprotection is much more difficult to accomplish. Although the negative studies obtained with the MAO-B inhibitor selegiline (deprenyl) and the antioxidant tocopherol (vitamin E) may have resulted from an inappropriate choice of drug (selegiline) or an inadequate dose (tocopherol), the niggling problem that still remains is why these drugs, and others, do work in animals while they fail in the clinic. One reason for this may be related to the fact that in normal human brains the number of dopaminergic neurons falls by around 3-5% every decade, while in Parkinson's disease this decline is greater. Brain autopsy studies have shown that by the time the disease is identified, some 70-75% of the dopamine-containing neurons have been lost. More sensitive reliable methods and clinical correlative markers are required to discern between confoundable symptomatic effects versus a possible neuroprotective action of drugs, namely, the ability to delay or forestall disease progression by protecting or rescuing the remaining dopamine neurons or even restoring those that have been lost.A number of other possibilities for the clinical failure of potential neuroprotectants also exist. First, the animal models of Parkinson's disease may not be totally reflective of the disease and, therefore, the chemical pathologies established in the animal models may not cause, or contribute to, the progression of the disease clinically. Second, because of the series of events occurring in neurodegeneration and our ignorance about which of these factors constitutes the primary event in the pathogenic process, a single drug may not be adequate to induce neuroprotection and, as a consequence, use of a cocktail of drugs may be more appropriate. The latter concept receives support from recent complementary DNA (cDNA) microarray gene expression studies, which show the existence of a gene cascade of events occurring in the nigrostriatal pathway of MPTP, 6-OHDA and methamphetamine animal models of Parkinson's disease. Even with the advent of powerful new tools such as genomics, proteomics, brain imaging, gene replacement therapy and knockout animal models, the desired end result of neuroprotection is still beyond our current capability.

Green Tea Polyphenol Epigallocatechin-3-gallate (EGCG) Differentially Inhibits Interleukin-1β-Induced Expression of Matrix Metalloproteinase-1 and -13 in Human Chondrocytes

Interleukin-1beta (IL-1beta)-induced inflammatory response in arthritic joints include the enhanced expression and activity of matrix metalloproteinases (MMPs), and their matrix degrading activity contribute to the irreversible loss of cartilage and may also be associated with sustained chronic inflammation. We have earlier shown that green tea (Camellia sinensis) polyphenol epigallocatechin-3-gallate (EGCG) was non-toxic to human chondrocytes [Singh R, Ahmed S, Islam N, Goldberg VM, and Haqqi TM (2002) Arthritis Rheum 46: 2079-2086] and inhibits the expression of inflammatory mediators in arthritic joints [Haqqi TM, Anthony DD, Gupta S, Ahmed N, Lee MS, Kumar GK, and Mukhtar H (1999) Proc Natl Acad Sci USA 96: 4524-4529]. Here we show that EGCG at micromolar concentrations was highly effective in inhibiting the IL-1beta-induced glycosaminoglycan (GAG) release from human cartilage explants in vitro. EGCG also inhibited the IL-1beta-induced mRNA and protein expression of MMP-1 and MMP-13 in human chondrocytes. Importantly, EGCG showed a differential, dose-dependent inhibitory effect on the expression and activity of MMP-13 and MMP-1. A similar differential dose-dependent inhibition of transcription factors NF-kappaB and AP-1 by EGCG was also noted. These results for the first time demonstrate a differential dose-dependent effect of EGCG on the expression and activity of MMPs and on the activities of transcription factors NF-kappaB and AP-1 and provide insights into the molecular basis of the reported anti-inflammatory effects of EGCG. These results also suggest that EGCG or compounds derived from it may be therapeutically effective inhibitors of IL-1beta-induced production of matrix-degrading enzymes in arthritis.

Articular cartilage biology

Articular cartilage is a complex tissue maintained by chondrocytes, which undergo metabolic changes as a result of aging, disease, and injury. These changes may hinder tissue maintenance and repair, resulting in accelerated loss of articular surface and leading to end-stage arthritis. Researchers are investigating both normal and pathologic cellular and molecular processes as well as the development of chondroprotective agents to improve the metabolic function of articular cartilage. Current research is helping to clarify the mechanisms by which a variety of agents, such as glucosamine, chondroitin sulfate, hyaluronic acid, green tea, glucocorticoids, and nonsteroidal anti-inflammatory drugs, can modify the symptoms and course of osteoarthritis. Also under investigation are methods of stimulating repair or replacing damaged cartilage, such as matrix metalloproteinase inhibitors, gene therapy, growth factors, cytokine inhibitors, and artificial cartilage substitutes. Tissue engineering, the combining of artificial matrices with cells and growth factors or genes, offers great potential for improving patient care.

Selective inhibition of ADAMTS-1, -4 and -5 by catechin gallate esters

Three mammalian ADAMTS enzymes, ADAMTS-1, -4 and -5, are known to cleave aggrecan at certain glutamyl bonds and are considered to be largely responsible for cartilage aggrecan catabolism observed during the development of arthritis. We have previously reported that certain catechins, polyphenolic compounds found in highest concentration in green tea (Camellia sinensis), are capable of inhibiting cartilage aggrecan breakdown in an in vitro model of cartilage degradation. We have now cloned and expressed recombinant human ADAMTS-1, -4 and -5 and report here that the catechin gallate esters found in green tea potently inhibit the aggrecan-degrading activity of these enzymes, with submicromolar IC50 values. Moreover, the concentration needed for total inhibition of these members of the ADAMTS group is approximately two orders of magnitude lower than that which is needed to partially inhibit collagenase or ADAM-10 activity. Catechin gallate esters therefore provide selective inhibition of certain members of the ADAMTS group of enzymes and could constitute an important nutritional aid in the prevention of arthritis as well as being part of an effective therapy in the treatment of joint disease and other pathologies involving the action of these enzymes.

Neuroprotection and neurorescue against Abeta toxicity and PKC-dependent release of nonamyloidogenic soluble precursor protein by green tea polyphenol (-)-epigallocatechin-3-gallate

Green tea extract and its main polyphenol constituent (-)-epigallocatechin-3-gallate (EGCG) possess potent neuroprotective activity in cell culture and mice model of Parkinson's disease. The central hypothesis guiding this study is that EGCG may play an important role in amyloid precursor protein (APP) secretion and protection against toxicity induced by beta-amyloid (Abeta). The present study shows that EGCG enhances (approximately 6-fold) the release of the non-amyloidogenic soluble form of the amyloid precursor protein (sAPPalpha) into the conditioned media of human SH-SY5Y neuroblastoma and rat pheochromocytoma PC12 cells. sAPPalpha release was blocked by the hydroxamic acid-based metalloprotease inhibitor Ro31-9790, which indicated mediation via alpha-secretase activity. Inhibition of protein kinase C (PKC) with the inhibitor GF109203X, or by down-regulation of PKC, blocked the EGCG-induced sAPPalpha secretion, suggesting the involvement of PKC. Indeed, EGCG induced the phosphorylation of PKC, thus identifying a novel PKC-dependent mechanism of EGCG action by activation of the non-amyloidogenic pathway. EGCG is not only able to protect, but it can rescue PC12 cells against the beta-amyloid (Abeta) toxicity in a dose-dependent manner. In addition, administration of EGCG (2 mg/kg) to mice for 7 or 14 days significantly decreased membrane-bound holoprotein APP levels, with a concomitant increase in sAPPalpha levels in the hippocampus. Consistently, EGCG markedly increased PKCalpha and PKC in the membrane and the cytosolic fractions of mice hippocampus. Thus, EGCG has protective effects against Abeta-induced neurotoxicity and regulates secretory processing of non-amyloidogenic APP via PKC pathway.

Protective effects of epicatechin against the toxic effects of streptozotocin on rat pancreatic islets: in vivo and in vitro

INTRODUCTION

Green tea catechins have diverse pharmacological effects such as anticarcinogenic and antioxidant activities.

AIM

To study the protective effects of green tea (-)-epicatechin (EC) against the toxic effects of streptozotocin (STZ), a selective beta cell toxin, on pancreatic islets in vivo and in vitro.

METHODOLOGY

Rats were randomly divided into four groups: control, EC (30 mg/kg)-treated, STZ (60 mg/kg)-treated, and EC plus STZ (same doses; EC+STZ)-treated rats. EC was administered twice a day for 6 days, and a single injection of STZ was used. In EC+STZ-treated rats, EC was administered 6 hours prior to STZ since posttreatment with EC had no beneficial effects on fully developed diabetes in our unpublished study. Insulin and insulin mRNA were detected by immunohistochemical analysis and in situ hybridization, respectively, and physiologic parameters including blood glucose concentration were measured daily. Following isolation of the islets, insulin release, nitrite levels, and islet morphology were observed in the four groups: control, EC (0.8 mM)-treated, STZ (5 mM)-treated, and EC+STZ (same doses)-treated islets.

RESULTS

In EC+STZ-treated rats, hyperglycemia and weight loss were not observed and islet morphology was well preserved compared with STZ-treated rats. Compared with STZ treatment alone, insulin release was increased and nitrite production was decreased in EC+STZ-treated islets.

CONCLUSION

EC appears to be helpful in protecting pancreatic islets against exposure to STZ in both in vivo and in vitro systems.

Efficacy of treatment with glycosaminoglycans on experimental collagen-induced arthritis in rats

To evaluate the antioxidant activity of the glycosaminoglycans hyaluronic acid (HYA) and chondroitin-4-sulphate (C4S), we used a rat model of collagen-induced arthritis (CIA). Arthritis was induced in Lewis rats by multiple intradermal injections of 250 microl of emulsion containing bovine type II collagen in complete Freund's adjuvant at the base of the tail and into three to five other sites on the back. Rats were challenged again with the same antigen preparation 7 days later. Disease developed about 11 days after the second immunization. The effects of treatment in the rats were monitored by biochemical parameters and by macroscopic and histological evaluations in blood, synovial tissue and articular cartilage. Arthritis produced the following symptoms: severe periarticular erythema, edema and inflammation in the hindpaws; membrane peroxidation in the cartilage of the joints; endogenous antioxidant wasting; high tumour necrosis factor-alpha (TNF-alpha) plasma levels; and synovial neutrophil accumulation. Treatment with HYA and C4S, starting at the onset of arthritis for 10 days, limited the erosive action of the disease in the articular joints of knee and paw, reduced lipid peroxidation, restored the endogenous antioxidants reduced glutathione (GSH) and superoxide dismutase, decreased plasma TNF-alpha levels, and limited synovial neutrophil infiltration. These data confirm that erosive destruction of the joint cartilage in CIA is due at least in part to free radicals released by activated neutrophils and produced by other biochemical pathways. The beneficial effects obtained with the treatment suggest that HYA and C4S could be considered natural endogenous macromolecules to limit erosive damage in CIA or as a useful tool with which to study the involvement of free radicals in rheumatoid arthritis.

Epigallocatechin-3-gallate selectively inhibits interleukin-1beta-induced activation of mitogen activated protein kinase subgroup c-Jun N-terminal kinase in human osteoarthritis chondrocytes

Activation of mitogen activated protein kinases (MAPK) is a critical event in pro-inflammatory cytokine-induced signaling cascade in synoviocytes and chondrocytes that lead to the production of several mediators of cartilage damage in an arthritic joint. Green tea (Camellia sinensis) is a widely consumed beverage and we earlier showed that polyphenols present in green tea (GTP) inhibit the development of inflammation and cartilage damage in an animal model of arthritis. In this study we evaluated the role of epigallocatechin-3-gallate (EGCG), a green tea polyphenol which mimics its anti-inflammatory effects, in modulating the IL-1beta-induced activation of MAPK's in human chondrocytes. We discovered that EGCG inhibited the IL-1beta-induced phosphorylation of c-Jun N-terminal kinase (JNK) isoforms, accumulation of phospho-c-Jun and DNA binding activity of AP-1 in osteoarthritis (OA) chondrocytes. Also IL-1beta, but not EGCG, induced the expression of JNK p46 without modulating the expression of JNK p54 in OA chondrocytes. In immunecomplex kinase assays, EGCG completely blocked the substrate phosphorylating activity of JNK but not of p38-MAPK. EGCG had no inhibitory effect on the activation of extracellular signal-regulated kinase p44/p42 (ERKp44/p42) or p38-MAPK in OA chondrocytes. EGCG or IL-1beta did not alter the total non-phosphorylated levels of either p38-MAPK or ERKp44/p42 in OA chondrocytes. These are novel findings and indicate that EGCG may be of potential benefit in inhibiting IL-1beta-induced catabolic effects in OA chondrocytes that are dependent on JNK activity.

Green tea polyphenol epigallocatechin-3-gallate inhibits the IL-1 beta-induced activity and expression of cyclooxygenase-2 and nitric oxide synthase-2 in human chondrocytes

We have previously shown that green tea polyphenols inhibit the onset and severity of collagen II-induced arthritis in mice. In the present study, we report the pharmacological effects of green tea polyphenol epigallocatechin-3-gallate (EGCG), on interleukin-1 beta (IL-1 beta)-induced expression and activity of cyclooxygenase-2 (COX-2) and inducible nitric oxide synthase (iNOS) in human chondrocytes derived from osteoarthritis (OA) cartilage. Stimulation of human chondrocytes with IL-1 beta (5 ng/ml) for 24 h resulted in significantly enhanced production of nitric oxide (NO) and prostaglandin E(2) (PGE(2)) when compared to untreated controls (p <.001). Pretreament of human chondrocytes with EGCG showed a dose-dependent inhibition in the production of NO and PGE(2) by 48% and 24%, respectively, and correlated with the inhibition of iNOS and COX-2 activities (p <.005). In addition, IL-1 beta-induced expression of iNOS and COX-2 was also markedly inhibited in human chondrocytes pretreated with EGCG (p <.001). Parallel to these findings, EGCG also inhibited the IL-1 beta-induced LDH release in chondrocytes cultures. Overall, the study suggests that EGCG affords protection against IL-1 beta-induced production of catabolic mediators NO and PGE(2) in human chondrocytes by regulating the expression and catalytic activity of their respective enzymes. Furthermore, our results also indicate that ECGC may be of potential therapeutic value for inhibiting cartilage resorption in arthritic joints.

Involvement of protein kinase C activation and cell survival/ cell cycle genes in green tea polyphenol (-)-epigallocatechin 3-gallate neuroprotective action

Studies from our laboratory have demonstrated that the major green tea polyphenol, (-)-epigallocatechin 3-gallate (EGCG), exerts potent neuroprotective actions in the mice model of Parkinson's disease. These studies were extended to neuronal cell culture employing the parkinsonism-inducing neurotoxin, 6-hydroxydopamine (6-OHDA). Pretreatment with EGCG (0.1-10 microm) attenuated human neuroblastoma (NB) SH-SY5Y cell death, induced by a 24-h exposure to 6-OHDA (50 microm). Potential cell signaling candidates involved in this neuroprotective effect were further examined. EGCG restored the reduced protein kinase C (PKC) and extracellular signal-regulated kinases (ERK1/2) activities caused by 6-OHDA toxicity. However, the neuroprotective effect of EGCG on cell survival was abolished by pretreatment with PKC inhibitor GF 109203X (1 microm). Because EGCG increased phosphorylated PKC, we suggest that PKC isoenzymes are involved in the neuroprotective action of EGCG against 6-OHDA. In addition, gene expression analysis revealed that EGCG prevented both the 6-OHDA-induced expression of several mRNAs, such as Bax, Bad, and Mdm2, and the decrease in Bcl-2, Bcl-w, and Bcl-x(L). These results suggest that the neuroprotective mechanism of EGCG against oxidative stress-induced cell death includes stimulation of PKC and modulation of cell survival/cell cycle genes.

Epigallocatechin-3-gallate inhibits interleukin-1beta-induced expression of nitric oxide synthase and production of nitric oxide in human chondrocytes: suppression of nuclear factor kappaB activation by degradation of the inhibitor of nuclear factor kappaB

OBJECTIVE

The proinflammatory cytokine interleukin-1beta (IL-1beta) induces the production of high levels of nitric oxide (NO) in human chondrocytes. Green tea (Camellia sinensis) polyphenols are potent antiinflammatory agents and have been shown to inhibit NO production in tumor cell lines. In the present study, we examined the effect of epigallocatechin-3-gallate (EGCG), a green tea polyphenol, on IL-1beta-induced production of NO in primary human osteoarthritis (OA) chondrocytes.

METHODS

Human chondrocytes were derived from OA cartilage and were treated with EGCG (100 microM) and IL-1beta (2 ng/ml) for different periods, and inducible nitric oxide synthase (iNOS) messenger RNA and protein expression was determined by real-time quantitative reverse transcriptase-polymerase chain reaction and Western blotting, respectively. Production of NO was determined as nitrite in culture supernatant. Activation and translocation of nuclear factor kappaB (NF-kappaB), levels of inhibitor of nuclear factor kappaB (IkappaB), and NF-kappaB DNA binding activity were determined by Western blotting and a highly sensitive and specific enzyme-linked immunosorbent assay. Activity of IkappaB kinase was determined using in vitro kinase assay.

RESULTS

Human chondrocytes cotreated with EGCG produced significantly less NO compared with chondrocytes stimulated with IL-1beta alone (P < 0.005). The inhibition of NO production correlated with the suppression of induction and expression of NF-kappaB-dependent gene iNOS. EGCG inhibited the activation and translocation of NF-kappaB to the nucleus by suppressing the degradation of its inhibitory protein IkappaBalpha in the cytoplasm.

CONCLUSION

Our results indicate that EGCG inhibits the IL-1beta-induced production of NO in human chondrocytes by interfering with the activation of NF-kappaB through a novel mechanism. Our data further suggest that EGCG may be a therapeutically effective inhibitor of IL-1beta-induced inflammatory effects that are dependent on NF-kappaB activation in human OA chondrocytes.

Catechins from green tea (Camellia sinensis) inhibit bovine and human cartilage proteoglycan and type II collagen degradation in vitro

Polyphenolic compounds from green tea have been shown to reduce inflammation in a murine model of inflammatory arthritis, but no studies have been undertaken to investigate whether these compounds are protective to joint tissues. We therefore investigated the effects of catechins found in green tea on cartilage extracellular matrix components using in vitro model systems. Bovine nasal and metacarpophalangeal cartilage as well as human nondiseased, osteoarthritic and rheumatoid cartilage were cultured with and without reagents known to accelerate cartilage matrix breakdown. Individual catechins were added to the cultures and the amount of released proteoglycan and type II collagen was measured by metachromatic assay and inhibition ELISA, respectively. Possible nonspecific or toxic effects of the catechins were assessed by lactate output and proteoglycan synthesis. Catechins, particularly those containing a gallate ester, were effective at micromolar concentrations at inhibiting proteoglycan and type II collagen breakdown. No toxic effects of the catechins were evident. We conclude that some green tea catechins are chondroprotective and that consumption of green tea may be prophylactic for arthritis and may benefit the arthritis patient by reducing inflammation and slowing cartilage breakdown. Further studies will be required to determine whether these compounds access the joint space in sufficient concentration and in a form capable of providing efficacy in vivo.

Suppression of azoxymethane-induced preneoplastic lesions and inhibition of cyclooxygenase-2 activity in the colonic mucosa of rats drinking a crude green tea extract

We determined the effects of a crude green tea extract given as drinking fluid on the promotion/progression phase of colon carcinogenesis in rats after induction of the neoplastic process by azoxymethane. Adult Wistar rats were given azoxymethane (15 mg/kg i.p.) once a week for two weeks. One week after the second injection, the rats were randomly divided into two groups. One group (n = 8) received daily prepared aqueous solutions of green tea extracts (GTE; 0.02%, wt/vol); the control group (n = 8) received tap water. After six weeks, rats receiving GTE showed a 60% reduction in the number of colonic preneoplastic lesions (aberrant crypts). The number of individual crypts per aberrant crypt focus (crypt multiplicity) was significantly reduced in the GTE group; the majority (80%) of the remaining aberrant foci contained only one or two preneoplastic crypts. A significant and selective decrease of cyclooxygenase (COX)-2 activity was observed in the colon of rats receiving GTE (23 +/- 3 vs. 117 +/- 30 mU/mg protein in controls), whereas COX-1 showed no alterations. Our data demonstrate that GTE reduces COX-2 and suppresses the formation of colonic preneoplastic lesions. They provide new insights into the mechanism of chemopreventive and anti-inflammatory properties of green tea.

Green tea polyphenol (-)-epigallocatechin-3-gallate prevents N-methyl-4-phenyl-1,2,3,6-tetrahydropyridine-induced dopaminergic neurodegeneration

In the present study we demonstrate neuroprotective property of green tea extract and (-)-epigallocatechin-3-gallate in N-methyl-4-phenyl-1,2,3,6-tetrahydropyridine mice model of Parkinson's disease. N-Methyl-4-phenyl-1,2,3,6-tetrahydropyridine neurotoxin caused dopamine neuron loss in substantia nigra concomitant with a depletion in striatal dopamine and tyrosine hydroxylase protein levels. Pretreatment of mice with either green tea extract (0.5 and 1 mg/kg) or (-)-epigallocatechin-3-gallate (2 and 10 mg/kg) prevented these effects. In addition, the neurotoxin caused an elevation in striatal antioxidant enzymes superoxide dismutase (240%) and catalase (165%) activities, both effects being prevented by (-)-epigallocatechin-3-gallate. (-)-Epigallocatechin-3-gallate itself also increased the activities of both enzymes in the brain. The neuroprotective effects are not likely to be caused by inhibition of N-methyl-4-phenyl-1,2,3,6-tetrahydropyridine conversion to its active metabolite 1-methyl-4-phenylpyridinium by monoamine oxidase-B, as both green tea and (-)-epigallocatechin-3-gallate are very poor inhibitors of this enzyme in vitro (770 microg/mL and 660 microM, respectively). Brain penetrating property of polyphenols, as well as their antioxidant and iron-chelating properties may make such compounds an important class of drugs to be developed for treatment of neurodegenerative diseases where oxidative stress has been implicated.

Upregulation of lymphocyte apoptosis as a strategy for preventing and treating autoimmune disorders: a role for whole-food vegan diets, fish oil and dopamine agonists

Induced apoptosis of autoreactive T-lymphocyte precursors in the thymus is crucial for the prevention of autoimmune disorders. IGF-I and prolactin, which are lymphocyte growth factors, may have the potential to suppress apoptosis in thymocytes and thus encourage autoimmunity; conversely, dietary fish oil rich in omega-3 fats appears to upregulate apoptosis in lymphocytes. Since whole-food vegan diets may downregulate systemic IGF-I activity, it is proposed that such a diet, in conjunction with fish oil supplementation and treatment with dopamine agonists capable of suppressing prolactin secretion, may have utility for treating and preventing autoimmune disorders. This prediction is consistent with the extreme rarity of autoimmune disorders among sub-Saharan black Africans as long as they followed their traditional quasi-vegan lifestyles, and with recent ecologic studies correlating risks for IDDM and for multiple sclerosis mortality with animal product and/or saturated fat consumption. Moreover, there is evidence that vegan or quasi-vegan diets are useful in the management of rheumatoid arthritis, multiple sclerosis, and possibly SLE. The dopamine agonist bromocryptine exerts anti-inflammatory effects in rodent models of autoimmunity, and there is preliminary evidence that this drug may be clinically useful in several human autoimmune diseases; better tolerated D2-specific agonists such as cabergoline may prove to be more practical for use in therapy. The moderate clinical utility of supplemental fish oil in rheumatoid arthritis and certain other autoimmune disorders is documented. It is not unlikely that extra-thymic anti-inflammatory effects contribute importantly to the clinical utility of vegan diets, bromocryptine, and fish oil in autoimmunity. The favorable impact of low latitude or high altitude on autoimmune risk may be mediated by superior vitamin D status, which is associated with decreased secretion of parathyroid hormone; there are theoretical grounds for suspecting that parathyroid hormone may inhibit apoptosis in thymocytes. Androgens appear to up-regulate thymocyte apoptosis, may be largely responsible for the relative protection from autoimmunity enjoyed by men, and merit further evaluation for the management of autoimmunity in women. It will probably prove more practical to prevent autoimmune disorders than to reverse them once established; a whole-food vegan diet, coupled with fish oil and vitamin D supplementation, may represent a practical strategy for achieving this prevention, while concurrently lowering risk for many other life-threatening 'Western' diseases.

A review of latest research findings on the health promotion properties of tea

Important progress has been made in the past five years concerning the effects of green and black tea on health. Experimentation with new accurate tools provide useful information about the metabolism of tea components in the body, their mode of action as antioxidants at the cellular level and their protective role in the development of cancer, cardiovascular disease and other pathologies. The use of tea components as nutraceuticals and functional foods are also discussed.

Green tea polyphenol extract attenuates inflammation in interleukin-2-deficient mice, a model of autoimmunity

Green tea polyphenols (GrTP) have been previously shown to decrease endotoxin-induced tumor necrosis factor-alpha production and lethality in mice. Our present studies demonstrate that GrTP inhibit inflammatory responses and may be useful in treating chronic inflammatory states, such as inflammatory bowel disease. In this preliminary study, we examined whether GrTP decrease disease activity in interleukin-2-deficient (IL-2(-/-) mice. Eight-week old IL-2(-/-) C57BL/6J mice who were fed nonpurified diet were randomly assigned to receive water with GrTP (5 g/L) or water alone (control) for up to 6 wk. After 1 wk, explant colon and lamina propria lymphocyte (LPL) cultures were established from a subgroup of mice and supernatants collected. Culture supernatants from GrTP-treated mice showed decreased spontaneous interferon-gamma and tumor necrosis factor-alpha secretion compared with that of controls. At 6 wk, the GrTP group had less severe colitis as demonstrated by lower histologic scores and wet colon weights. This was associated with lower plasma levels of serum amyloid A, increased weight gain and improved hematocrits. These results show that GrTP attenuated inflammation in IL-2(-/-) mice and suggest a role for GrTP in treating chronic inflammatory diseases such as inflammatory bowel disease.

Bioavailability of flavonoids and potential bioactive forms in vivo

Flavonoids are powerful antioxidants in vitro, but their overall functions in vivo have yet to be clarified, whether antioxidant, anti-inflammatory, enzyme inhibitor or inducer, or some other role. The reducing properties of flavonoids might also contribute to redox regulation in cells independently of their antioxidant properties. However, in order to understand their bioactivity in vivo, it is necessary to understand the factors influencing the absorption of flavonoids by the gastrointestinal tract, the nature of the conjugates and metabolites in the circulation and how this influences their antioxidant activities.

Neuroprotective effect of green tea extract in experimental ischemia-reperfusion brain injury

Eicosanoids accumulation and formation of oxygen free radicals have been implicated in the pathogenesis of ischemia/reperfusion brain injury. In the present study, we examined whether green tea extract protects against ischemia/reperfusion-induced brain injury by minimizing eicosanoid accumulation and oxygen radical-induced oxidative damage in the brain. Green tea extract (0.5%) was orally administered to Wistar rats for 3 weeks before induction of ischemia. Ischemia was induced by the occlusion of middle cerebral arteries for 60 min and reperfusion was achieved for 24 h. Infarction volume in the ipsilateral hemisphere of ischemia/reperfusion animals was 114 +/- 16 mm(3) in the 0.5% green tea pretreated animals compared to 180 +/- 54 mm(3) in left hemisphere of nontreated animals. Green tea extract (0.5%) also reduced ischemia/reperfusion-induced eicosanoid concentration: Leukotriene C(4) (from 245 +/- 51 to186 +/- 22), prostoglandin E(2) (from 306 +/- 71 to 212 +/- 43) and thromboxane A(2) (327 +/- 69 to 251 +/- 87 ng/mg protein). Ischemia/reperfusion-induced increases of hydrogen peroxide level (from 688 +/- 76 to 501 +/- 99 nmole/mg protein), lipid peroxidation products (from 1010 +/- 110 to 820 +/- 70 nmole/mg protein) and 8-oxodG formation (from 1.3 +/- 0.3 to 0.8 +/- 0.2 ng/microg DNA, x10(-2)) were also reduced. Moreover, 0.5% green tea extract also reduced the apoptotic cell number (from 44 +/- 11 to 29 +/- 1 in the striatum, and from 72 +/- 11 to 42 +/- 5 apoptotic cells/high power field in the cortex region). Green tea extract pretreatment also promoted recovery from the ischemia/reperfusion-induced inhibition of active avoidance. The present study shows that the minimizing effect of green tea extract on the eicosanoid accumulation and oxidative damage in addition to the reduction of neuronal cell death could eventually result in protective effect on the ischemia/reperfusion-induced brain injury and behavior deficit.

Effects of tea consumption on nutrition and health

Beneficial health effects of tea have been demonstrated in animal experiments and some human studies. The two most extensively investigated diseases are cancer and heart disease. Although mechanisms of protective activity of tea against these diseases have been proposed, there are inconsistencies in the relationship between tea consumption and the risk of these diseases in humans. The bioavailability of active components is beginning to be understood, but further research is required to determine whether the results from animal studies are applicable to humans. Also discussed are the possible effects of tea in increasing thermogenesis and bone density as well as decreasing risk of cataracts and arthritis. The potential health benefits of tea consumption warrant further investigation.

Eat to live, not live to eat

Most of the prevailing chronic diseases in the world have an important nutritional component by directly causing a specific disease, enhancing the risk through phenomena of promotion, exerting a beneficial effect in decreasing risk, or preventing the disease. International studies in geographic pathology have shown that a given disease may have vastly different incidence and mortality as a function of residence. Laboratory research in animal models can reproduce fairly accurately what is learned through international research and provide the basis for examining relevant hypotheses and, more importantly, proposed mechanisms of action. Validation of these approaches can be the basis for public-health recommendations and health-promotion activities. Through such techniques, it has been found that regular intake of foods with saturated fats such as meat and certain dairy products raise the risk of coronary heart disease. The total mixed-fat intake is associated with a higher incidence of the nutritionally linked cancers, specifically cancer of the postmenopausal breast, distal colon, prostate, pancreas. ovary, and endometrium. The associated genotoxic carcinogens for several of these cancers are heterocyclic amines, which also play a role in heart-disease causation, and these are produced during the broiling and frying of creatinine-containing foods such as meats. Monounsaturated oils such as olive or canola oil are low-risk fats as shown in animal models and through the observation that the incidence of specific diseases is lower in the Mediterranean region, where such oils are customarily used. High salt intake is associated with high blood pressure and with stomach cancer, especially with inadequate intake of potassium from fruits and vegetables and of calcium from certain vegetables and low-fat dairy products. Vegetables, fruits, and soy products are rich in antioxidants that are essential to lower disease risk stemming from reactive oxygen systems in the body. Green and black teas are excellent sources of antioxidants of a polyphenol nature. as is cocoa and some chocolates. Nutritional lifestyles that offer the possibility of a healthy long life can be adopted by most populations in the world.

Prevention of collagen-induced arthritis in DBA/1 mice by oral administration of AZ-9, a bacterial polysaccharide from Klebsiella oxytoca

Collagen-induced arthritis (CIA) is an excellent model of rheumatoid arthritis (RA) in humans that is induced in DBA/1 mice immunized with bovine type II collagen (CII). Here, we report that the induction of CIA was effectively suppressed by oral administration of AZ-9, a purified polysaccharide with the average molecular weight of approximately 200 kDa that was produced by a soil bacterium, Klebsiella oxytoca. When AZ-9 was administered at 125-250 mg/kg/day orally for 9 consecutive days after immunization with CII followed by its administration every 3 days, resulted in a marked reduction of the incidence and the severity of CIA. The serum level of anti-CII IgG2a and the production of IFN-gamma and IL-12 in the draining lymph node (LN) cells were significantly lower in AZ-9-administered mice than the untreated control. These findings suggest that orally administered AZ-9 suppressed CIA through attenuating a Th1-type response to CII. AZ-9 could be fragmented into smaller molecules (3-4 kDa) without losing its suppressive activity.

Cell cycle dysregulation by green tea polyphenol epigallocatechin-3-gallate

Epidemiological, in vitro cell culture, and in vivo animal studies have shown that green tea or its constituent polyphenols, particularly its major polyphenol epigallocatechin-3-gallate (EGCG) may protect against many cancer types. In earlier studies, we showed that green tea polyphenol EGCG causes a G0/G1-phase cell cycle arrest and apoptosis of human epidermoid carcinoma (A431) cells. We also demonstrated that these effects of EGCG may be mediated through the inhibition of nuclear factor kappa B that has been associated with cell cycle regulation and cancer. In this study, employing A431 cells, we provide evidence for the involvement of cyclin kinase inhibitor (cki)-cyclin-cyclin-dependent kinase (cdk) machinery during cell cycle deregulation by EGCG. As shown by immunoblot analysis, EGCG treatment of the cells resulted in significant dose- and time-dependent (i) upregulation of the protein expression of WAF1/p21, KIP1/p27, p16 and p18, (ii) downmodulation of the protein expression of cyclin D1, cdk4 and cdk6, but not of cyclin E and cdk2, (iii) inhibition of the kinase activities associated with cyclin E, cyclin D1, cdk2, cdk4 and cdk6. Taken together, our study suggests that EGCG causes an induction of G1-phase ckis, which inhibit the cyclin-cdk complexes operative in G0/G1 phase of the cell cycle thereby causing a G0/G1-phase arrest of the cell cycle, which is an irreversible process ultimately resulting in an apoptotic cell death. We suggest that the naturally occurring agents such as green tea polyphenols which may inhibit cell cycle progression could be developed as potent anticancer agents for the management of cancer.

Reduction of oxidative stress and cytokine-induced neutrophil chemoattractant (CINC) expression by red wine polyphenols in zinc deficiency induced intestinal damage of rat

Consumption of red wine has been associated with health promotion and disease prevention. We have previously found that the intestine of zinc-deficient (ZD) rats develop oxidative damage associated with inflammation. Here we have used this model to investigate whether red wine polyphenols could protect against intestinal injury and, if so, whether this protection was achieved through antioxidant and anti-inflammatory activity. The intestinal alterations induced by zinc deficiency such as morphological damage, increased TBA-RS level and CuZn-superoxide dismutase activity, and decreased glutathione peroxidase activity, did not develop with the administration to ZD rats of a suspension of dealcoholated red wine (RWS). The same treatment induced in control rats a decrease of TBA-RS level but also of glutathione peroxidase and catalase activity. Treatment with RWS to ZD rats prevented a marked mucosal macrophage and neutrophil infiltration. The expression of pro-inflammatory cytokines, such as tumor necrosis factor alpha and cytokine-induced neutrophil chemoattractant (CINC), was induced by zinc deficiency, whereas that of the anti-inflammatory interleukin-10 was suppressed. Treatment with RWS reduced CINC expression. These results report a novel activity of red wine polyphenols in downregulation of intestinal CINC expression, which likely protects cells against inflammatory processes.

Involvement of caspase-3 in epigallocatechin-3-gallate-mediated apoptosis of human chondrosarcoma cells

Green tea polyphenol-(-)epigallocatechin-3-gallate (EGCG)-is a potent chemopreventive agent in many test systems and has been shown to inhibit tumor promotion and induce apoptosis. In this study we describe a novel observation that EGCG displayed strong inhibitory effects on the proliferation and viability of HTB-94 human chondrosarcoma cells in a dose-dependent manner and induced apoptosis. Investigation of the mechanism of EGCG-induced apoptosis revealed that treatment with EGCG resulted in DNA fragmentation, induction of caspase-3/CPP32 activity, and cleavage of the death substrate poly(ADP-ribose)polymerase (PARP). Pretreatment of cells with a synthetic pan-caspase inhibitor (Z-VAD-FMK) and a caspase-3-specific inhibitor (DEVD-CHO) prevented EGCG-induced PARP cleavage. The induction of apoptosis by EGCG via activation of caspase-3/CPP32-like proteases may provide a mechanistic explanation for its antitumor effects.