(-)-Epigallocatechin-3-gallate induces up-regulation of Th1 and Th2 cytokine genes in Jurkat T cells

The anti-allergic potential of tea: a review of its components, mechanisms and risks

Allergy is an immune-mediated disease with increasing prevalence worldwide. Regular treatment with glucocorticoids and antihistamine drugs for allergy patients is palliative rather than permanent. Daily use of dietary anti-allergic natural products is a superior way to prevent allergy and alleviate the threat. Tea, as a health-promoting beverage, has multiple compounds with immunomodulatory ability. Persuasive evidence has shown the anti-allergic ability of tea against asthma, food allergy, atopic dermatitis and anaphylaxis. Recent advances in potential anti-allergic ability of tea and anti-allergic compounds in tea have been reviewed in this paper. Tea exerts its anti-allergic effect mainly by reducing IgE and histamine levels, decreasing FcεRI expression, regulating the balance of Th1/Th2/Th17/Treg cells and inhibiting related transcription factors. Further research perspectives are also discussed.

Induction of cellular and molecular immunomodulatory pathways by vitamin A and flavonoids

INTRODUCTION

A detailed study of reports on the immunomodulatory properties of vitamin A and select flavonoids may pave the way for using these natural compounds or compounds with similar structures in novel drug and vaccine designs against infectious and autoimmune diseases and cancers.

AREAS COVERED

Intracellular transduction pathways, cellular differentiation and functional immunomodulatory responses have been reviewed. The reported studies encompass in vitro, in vivo preclinical and clinical studies that address the role of vitamin A and select flavonoids in induction of innate and adaptive B- and T-cell responses, including TH1, TH2 and regulatory T cells (Treg).

EXPERT OPINION

While the immunomodulatory role of vitamin A, and related compounds, is well-established in many preclinical studies, its role in humans has begun to gain wider acceptance. In contrast, the role of flavonoids is mostly controversial in clinical trials, due to the diversity of the various classes of these compounds, and possibly due to the purity and the selected doses of the compounds. However, current preclinical and clinical studies warrant further detailed studies of these promising immunomodulatory compounds.

Immunomodulating effects of epigallocatechin-3-gallate from green tea: mechanisms and applications

Consuming green tea or its active ingredient, epigallocatechin-3-gallate (EGCG), has been shown consistently to benefit the healthy functioning of several body systems. In the immune system specifically, accumulating evidence has revealed an immunomodulating effect of green tea/EGCG. Several types of immune cells in both the innate and adaptive immune systems are known to be affected in varying degrees by green tea/EGCG. Among them, the dramatic effect on T cell functions has been repeatedly demonstrated, including T cell activation, proliferation, differentiation, and production of cytokines. In particular, dysregulated T cell function with respect to different subsets of CD4(+) T cells is a critical pathogenic factor in the development of autoimmune inflammatory diseases. Recent studies have shown that EGCG affects the differentiation of naïve CD4(+) T cells into different effector subsets in a way that would be expected to favorably impact autoimmunity. Consistent with these findings, studies using animal models of autoimmune diseases have reported disease improvement in animals treated with green tea/EGCG. Altogether, these studies identify and support the use of EGCG as a potential therapeutic agent in preventing and ameliorating T cell-mediated autoimmune diseases. Given the paucity of information in human studies, the translational value of these findings needs to be verified in future research.

The effect of epigallocatechin-3-gallate (EGCG) on human alveolar bone cells both in vitro and in vivo

OBJECTIVE

The effects of epigallocatechin-3-gallate (EGCG), a major catechin in green tea, on human and mouse osteoblasts remain controversial. This study investigated the direct effects of EGCG on human alveolar bone-derived cells (hABCs) both in vitro and in vivo.

DESIGN

hABCs which were collected from eight children (aged 7-9 years, seven males and one female) were treated with EGCG at various concentrations (1, 5, 10, 25, and 50μM), and a proliferation assay, flow cytometric analysis for apoptosis evaluation, migration assay, and in vitro osteogenic differentiation were performed. hABCs that were pretreated with 10μM EGCG and mixed with calcium phosphate carrier combined with EGCG (0.1, 0.5, or 1.5mg) in vivo were transplanted into immunodeficient mouse. Histological staining, quantitative gene expressions, and alkaline phosphatase activity were evaluated in the retrieved transplants.

RESULTS

The proliferation and migration were decreased when EGCG was present at over 25μM. The osteogenic differentiation increased slightly when EGCG was present at up to 10μM, and clearly decreased for higher concentrations of EGCG. In vivo, the potential for hard-tissue formation was slightly higher for the group with 0.1mg of EGCG than for the control group, and decreased sharply for higher concentrations of EGCG.

CONCLUSION

The present observations suggest that EGCG at a low concentration can slightly enhance the osteogenic effect in vivo, whereas at a higher concentration it can prevent the osteogenic differentiation of hABCs both in vitro and in vivo.

Detailed analysis of apoptosis and delayed luminescence of human leukemia Jurkat T cells after proton irradiation and treatments with oxidant agents and flavonoids

Following previous work, we investigated in more detail the relationship between apoptosis and delayed luminescence (DL) in human leukemia Jurkat T cells under a wide variety of treatments. We used menadione and hydrogen peroxide to induce oxidative stress and two flavonoids, quercetin, and epigallocatechin gallate, applied alone or in combination with menadione or H₂O₂. 62 MeV proton beams were used to irradiate cells under a uniform dose of 2 or 10 Gy, respectively. We assessed apoptosis, cell cycle distributions, and DL. Menadione, H₂O₂ and quercetin were potent inducers of apoptosis and DL inhibitors. Quercetin decreased clonogenic survival and the NAD(P)H level in a dose-dependent manner. Proton irradiation with 2 Gy but not 10 Gy increased the apoptotic rate. However, both doses induced a substantial G₂/M arrest. Quercetin reduced apoptosis and prolonged the G₂/M arrest induced by radiation. DL spectroscopy indicated that proton irradiation disrupted the electron flow within Complex I of the mitochondrial respiratory chain, thus explaining the massive necrosis induced by 10 Gy of protons and also suggested an equivalent action of menadione and quercetin at the level of the Fe/S center N2, which may be mediated by their binding to a common site within Complex I, probably the rotenone-binding site.

Involvement of intracellular oxidative stress-sensitive pathway in phloxine B-induced photocytotoxicity in human T lymphocytic leukemia cells

We investigated the molecular mechanisms underlying phloxine B (PhB)-induced photocytotoxicity in human T lymphocytic leukemia Jurkat cells. In addition to apoptosis-related biochemical events, photo-irradiated PhB generated intracellular reactive oxygen species (ROS), induced phosphorylation of c-Jun-N-terminal kinase (JNK) in an oxidative stress-dependent manner and up-regulated the gene expression of interferon (IFN)-γ, an inducer of diverse apoptosis-related molecules in activated T cells. PhB-induced apoptosis was significantly inhibited by N-acetyl-l-cysteine, but not by catalase, indicating that ROS generation occurred intracellularly, and by SP600125 and AG490, specific inhibitors of JNK and IFN-γ signaling, respectively, confirming their roles in the apoptotic pathway. IFN-γ up-regulation was also inhibited by SP600125, indicating that it was downstream of JNK activation. These results suggest that PhB-induced apoptosis in Jurkat cells partially involves the intracellular oxidative stress-sensitive and T cell-specific IFN-γ pathway. These data present a novel insight into the mechanisms of photocytotoxicity induced by artificial food colorants in human T lymphocytic leukemia cells.

Preclinical prophylactic efficacy testing of Sm-p80-based vaccine in a nonhuman primate model of Schistosoma mansoni infection and immunoglobulin G and E responses to Sm-p80 in human serum samples from an area where schistosomiasis is endemic

The prophylactic efficacy of a schistosome antigen (Sm-p80) was tested in a nonhuman primate model, the baboon. Using a total of 28 baboons, different vaccination strategies were used including recombinant Sm-p80 protein formulated in Toll-like receptor 7 and Toll-like receptor 9 agonists, and DNA priming followed by boosting with protein plus adjuvants. Recombinant protein approaches provided levels of prophylactic efficacy of 52%-58%, whereas prime-boost approaches conferred 38%-47% protection in baboons. An appropriately balanced pro-inflammatory (T-helper 17 [Th17] and Th1) and anti-inflammatory (Th2) type of response was generated; the Th1 and Th17 types of immune responses appear to be indicative of increased prophylactic efficacy. Production and expression of several cytokines (interleukin 2 [IL-2], interferon γ, IL-12α, IL-1β, IL-6, and IL-22) were up-regulated in vaccinated animals. Human correlate studies revealed Sm-p80 reactivity with immunoglobulin G in human serum samples from schistosome-infected individuals. In addition, a complete lack of prevailing Sm-p80-specific immunoglobulin E in a high-risk or infected population was observed, thus minimizing the risk of hypersensitivity reaction following vaccination with Sm-p80 in humans. This study provided the proof of concept to move Sm-p80 forward into further preclinical development leading to human clinical trials.

Green tea and bone health: Evidence from laboratory studies

Osteoporosis is a major health problem in the elderly. Epidemiological evidence has shown an association between tea consumption and the prevention of bone loss in the elderly population. Ingestion of green tea and green tea bioactive compounds may be beneficial in mitigating bone loss of this population and decreasing their risk of osteoporotic fractures. This review describes the effect of green tea with its bioactive components on bone health with an emphasis on the following: (i) the etiology of osteoporosis, (ii) evidence of osteo-protective impacts of green tea on bone mass and microarchitecture in various bone loss models in which induced by aging, sex hormone deficiency, and chronic inflammation, (iii) discussion of impacts of green tea on bone mass in two obesity models, (iv) observation of short-term green tea supplementation given to postmenopausal women with low bone mass, (v) possible mechanisms for the osteo-protective effects of green tea bioactive compounds, and (vi) a summary and future research direction of green tea and bone health.

MnTMPyP, a superoxide dismutase/catalase mimetic, decreases inflammatory indices in ischemic acute kidney injury

OBJECTIVE

This study investigates the effect of a superoxide dismutase mimetic, MnTMPyP, on pro- and anti-inflammatory cytokines in acute renal ischemia-reperfusion (IR).

MATERIALS AND TREATMENT

Male Sprague-Dawley rats underwent bilateral clamping of the renal arteries for 45 min followed by 1, 4, or 24 h of reperfusion. A subset of animals was treated with MnTMPyP (5 mg/kg, i.p.) or saline. Porcine proximal tubular epithelial cells were ATP-depleted for 4 h followed by recovery for 2 h.

METHODS

Cytokines were analyzed by ELISA, and ED1(+) macrophages and CD8(+) T lymphocytes by immunohistochemistry. Statistical analysis was performed using ANOVA.

RESULTS

MnTMPyP attenuated the IR-mediated increase in serum creatinine and circulating levels of interleukin (IL)-2 following 24 h of reperfusion. Furthermore, treatment attenuated increases in tissue levels of tumor necrosis factor (TNF)-α, IL-2, IL-4, and IL-13. MnTMPyP partially prevented the IR-induced infiltration of ED1(+) macrophages and CD8(+) T lymphocytes in the kidney. ATP depletion-recovery of porcine proximal tubular epithelial cells resulted in decreased IL-6 and IL-10 levels, and MnTMPyP partially restored these cytokines.

CONCLUSIONS

These results show that MnTMPyP is partially effective in reducing inflammation associated with renal IR and that reactive oxygen species play a role in modulating both pro- and anti-inflammatory pathways in acute kidney injury.

Green tea and bone metabolism

Osteoporosis is a major health problem in both elderly women and men. Epidemiological evidence has shown an association between tea consumption and the prevention of age-related bone loss in elderly women and men. Ingestion of green tea and green tea bioactive compounds may be beneficial in mitigating bone loss of this population and decreasing their risk of osteoporotic fractures. This review describes the effect of green tea or its bioactive components on bone health, with an emphasis on (i) the prevalence and etiology of osteoporosis; (ii) the role of oxidative stress and antioxidants in osteoporosis; (iii) green tea composition and bioavailability; (iv) the effects of green tea and its active components on osteogenesis, osteoblastogenesis, and osteoclastogenesis from human epidemiological, animal, as well as cell culture studies; (v) possible mechanisms explaining the osteoprotective effects of green tea bioactive compounds; (vi) other bioactive components in tea that benefit bone health; and (vii) a summary and future direction of green tea and bone health research and the translational aspects. In general, tea and its bioactive components might decrease the risk of fracture by improving bone mineral density and supporting osteoblastic activities while suppressing osteoclastic activities.