Yin Yang 1 Promotes Thymocyte Survival by Downregulating p53.

Yin Yang 1 (YY1) is a zinc finger protein that functions as a transcriptional activator or repressor and participates in multiple biological processes, including development and tumorigenesis. To investigate the role of YY1 in developing T cells, we used mouse models that depleted YY1 at two distinct stages of thymocyte development. When YY1 was depleted in CD4(-)CD8(-) double-negative thymocytes, development to the CD4(+)CD8(+) double-positive stage was impaired, due to increased apoptosis that prevented expansion of post-ß-selection thymocytes. When YY1 was depleted in double-positive thymocytes, they underwent increased cell-autonomous apoptosis in vitro and displayed a shorter lifespan in vivo, as judged by their ability to undergo secondary Vα-to-Jα recombination. Mechanistically, we found that the increased apoptosis in YY1-deficient thymocytes was attributed to overexpression of p53, because concurrent loss of p53 completely rescued the developmental defects of YY1-deficient thymocytes. These results indicated that YY1 functions as a critical regulator of thymocyte survival and that it does so by suppressing the expression of p53.

Inhibitive effects of nickel chloride (NiCl2) on thymocytes.

The purpose of this study was to define the inhibitive effects of dietary nickel chloride (NiCl2) on thymocytes in broilers fed on diets supplemented with 0, 300, 600, and 900 mg/kg of NiCl2 for 42 days. We examined the changes of cell cycle phase, percentages of apoptotic cells, T cell subsets, cytokines, and mRNA expression of apoptotic proteins (bcl-2, bax, and caspase-3) in thymocytes by flow cytometry and quantitative real-time polymerase chain reaction (qRT-PCR). In the NiCl2-treated broilers, the percentages of thymocytes in G0/G1 phase were increased, whereas thymocytes in the S phase and the proliferation index were decreased. The percentages of apoptotic thymocytes were increased. Also, the mRNA expression levels of bax and caspase-3 were increased, and mRNA expression levels of bcl-2 were decreased. The percentages of CD3(+), CD3(+)CD4(+), and CD3(+)CD8(+) T lymphocytes in the thymus and peripheral blood were diminished. Concurrently, thymic cytokine (interleukin-1 beta (IL-1ß), interleukin-2 (IL-2), interleukin-10 (IL-10), interleukin-12 p35 subunit (IL-12p35), interleukin-12 p40 subunit (IL-12p40), interleukin-21 (IL-21), interferon gamma (IFN-γ), tumor necrosis factor alpha (TNF-α), thymosin ß4, thymosin ß10, and thymosin ß15) mRNA expression levels were decreased. The abovementioned results showed that dietary NiCl2 in excess of 300 mg/kg inhibited thymocyte growth by arresting cell cycle, increasing apoptosis percentage, altering apoptotic protein mRNA expression levels, and downregulating cytokine expression levels.

Pectic polysaccharide from the green fruits of Momordica charantia (Karela): structural characterization and study of immunoenhancing and antioxidant properties.

A water soluble pectic polysaccharide (PS) isolated from the aqueous extract of the green fruits of Momordica charantia contains D-galactose and D-methyl galacturonate in a molar ratio of nearly 1:4. It showed splenocyte, thymocyte as well as macrophage activations. Moreover, it exhibited potent antioxidant activities. On the basis of total acid hydrolysis, methylation analysis, periodate oxidation, and 1D and 2D NMR studies, the structure of the repeating unit of the pectic polysaccharide was established as: [Formula: see text].

Curcuma longa attenuates carbon tetrachloride-induced oxidative stress in T-lymphocyte subpopulations.

A comparison of crude curcuminoid extract and purified curcumin was made to evaluate the immunoprotective effect of Curcuma longa (turmeric) Zingiberaceae. Carbon tetrachloride (CCl4) induced selective cytolytic effects among immature (PNA(+)) thymocytes and peripheral helper (CD4(+)) T lymphocytes in the spleen were paralleled by a significant reduction in CD25, CD71, and Con A receptor expression. Treatment with curcumanoid crude extract, at two different doses, showed a significant restoration of lymphocyte viability and CD25, CD71, and Con A receptor expression in both immature (PNA+) thymocytes and splenic helper (CD4(+)) T lymphocytes. Turmeric crude extract, at both low and high dose, was found to be more efficient as compared to purified curcumin, suggesting synergistic effect of curcumin with other components of the crude extract.

The role of T-cell receptor recognition of peptide:MHC complexes in the formation and activity of Foxp3⁺ regulatory T cells.

Foxp3(+) regulatory T (Treg) cells are required to prevent the immune system from spontaneously mounting a severe autoaggressive lymphoproliferative disease and can modulate immune responses in a variety of settings, including infections. In this review, we describe studies that use transgenic mice to determine how signals through the T-cell receptor (TCR) contribute to the development, differentiation, and activity of Treg cells in in vivo settings. By varying the amount and quality of the self-peptide recognized by an autoreactive TCR, we have shown that the interplay between autoreactive thymocyte deletion and Treg cell formation leads to a Treg cell repertoire that is biased toward low abundance agonist self-peptides. In an autoimmune disease setting, we have demonstrated that diverse TCR specificities can be required in order for Treg cells to prevent disease in a mouse model of autoimmune inflammatory arthritis. Lastly, we have shown that Treg cells initially selected based on specificity for a self-peptide can be activated by TCR recognition of a viral peptide, and that they can acquire a specialized phenotype and suppress antiviral effector cell activity at the site of infection. These studies provide insights into the pivotal role that TCR specificity plays in the formation and activity of Treg cells.

Water-soluble polysaccharides from finger citron fruits (Citrus medica L. var. sarcodactylis).

Four water-soluble polysaccharides, FCp-1, FCp-2, FCp-3, and FCp-4 were obtained from finger citron fruits (Citrus medica L. var. sarcodactylis) by hot-water extraction and ethanol precipitation, followed by routine separation procedure. Based on the calibration curve, molecular weights of them were estimated to be 113.9, 32.6, 140.3, and 177.1 kDa respectively. The acid hydrolysis, methylation, IR, GC-MS, and NMR experiments were used for composition analysis. FCp-1 was a heteropolysaccharide composed of arabinose, galactose, glucose, rhamnose, and xylose, with a molar ratio of 3.0:7.0:4.1:1.0:1.5. FCp-2 and FCp-4 were →4)-α-D-GalpA(1→ linking galacturonan differ in molecular weights. FCp-3 was a →6)-α-D-Glcp(1→ linking glucan. According to the results of in vitro assays, FCp-3 showed significantly and moderately enhancing capacities toward the proliferation of splenocytes and thymocytes respectively. Thus, FCp-3 or analogs may have further use as immunomodulatory agents.

Impairment of thymocyte function via induction of apoptosis by areca nut extract.

Areca quid (AQ) chewing is a popular oral habit, especially in Southeast Asia cultures, in which children may be engaged in the addictive habit early in their lives. Extracts of areca nuts, the main component of AQ, have been shown to affect the functionality of T-cells. However, the potential influence of ANE on the development of T-cells is unknown. This study, therefore, investigated the impact of areca nut extracts (ANE) on thymocytes and the potential mechanisms of action. Mice administered intraperitoneally with ANE at 1, 5, or 25 mg/kg daily for 5 days showed significant dose-dependent reductions in thymocyte viability. A marked decrease in the total number of thymocytes and the proportion of thymic CD4(+)CD8(+) cells was observed in the 25 mg ANE/kg-treated mice, whereas the proportion of CD4 and CD8 single positive and CD4(-)CD8(-) cells was significantly increased. Further examination on the functionality of thymocytes showed that ANE suppress IL-2 production both ex vivo and in vitro. These results suggest that ANE may attenuate the development and functionality of thymic T-cells. ANE also directly induced apoptosis in thymic T-cells through activation of casapase-3 and apoptosis inducing factor (AIF). Collectively, the data suggested that the thymus is a sensitive target to ANE. Early exposure to ANE may interfere with the development and functionality of thymic T-cells.

Immunomodulatory role of Emblica officinalis in arsenic induced oxidative damage and apoptosis in thymocytes of mice.

BACKGROUND: Arsenic is widely distributed in the environment and has been found to be associated with the various health related problems including skin lesions, cancer, cardiovascular and immunological disorders. The fruit extract of Emblica officinalis (amla) has been shown to have anti-oxidative and immunomodulatory properties. In view of increasing health risk of arsenic, the present study has been carried out to investigate the protective effect of amla against arsenic induced oxidative stress and apoptosis in thymocytes of mice. METHODS: Mice were exposed to arsenic (sodium arsenite 3 mg/kg body weight p.o.) or amla (500 mg/kg body weight p.o.) or simultaneously with arsenic and amla for 28 days. The antioxidant enzyme assays were carried out using spectrophotometer and generation of ROS, apoptotic parameters, change in cell cycle were carried out using flow cytometer following the standard protocols. RESULTS: Arsenic exposure to mice caused a significant increase in the lipid peroxidation, ROS production and decreased cell viability, levels of reduced glutathione, the activity of superoxide dismutase, catalase, cytochrome c oxidase and mitochondrial membrane potential in the thymus as compared to controls. Increased activity of caspase-3 linked with apoptosis assessed by the cell cycle analysis and annexin V/PI binding was also observed in mice exposed to arsenic as compared to controls. Co-treatment with arsenic and amla decreased the levels of lipid peroxidation, ROS production, activity of caspase-3, apoptosis and increased cell viability, levels of antioxidant enzymes, cytochrome c oxidase and mitochondrial membrane potential as compared to mice treated with arsenic alone. CONCLUSIONS: The results of the present study exhibits that arsenic induced oxidative stress and apoptosis significantly protected by co-treatment with amla that could be due to its strong antioxidant potential.

A new arabinoxylan from green leaves of Litsea glutinosa (Lauraeae): structural and biological studies.

A water soluble new arabinoxylan, isolated through hot water extraction from the green leaves of Litsea glutinosa (Lauraceae) was found to contain xylose and arabinose in a molar ratio of nearly 1:3. On the basis of NMR ((1)H, (13)C, DQF-COSY, TOCSY, NOESY, ROESY, HMBC and DEPT-135), GLC and GLC-MS analyses, the backbone was established as (1→4)-α-D-xylopyranosyl residue, substituted at C-2 with one unit of two adjacently linked (1→3)-α-L-arabinofuranosyl residues and the other one was terminated by ß-L-arabinofuranosyl residue. The proposed repeating unit of the molecule was established as: [formula, see text] This molecule showed strong splenocyte, thymocyte, and macrophage activations. The optimum doses of the polysaccharide for splenocyte and thymocyte proliferation were observed at 25 µg/mL and 50 µg/mL, respectively. An enhanced production of NO was observed at 100 µg/mL of the polysaccharide.

Elemental mapping by electron energy loss spectroscopy in biology.

Over the past decades there have been significant advances in transmission electron microscopy for biological applications, including in energy filtering and spectrum imaging, which are techniques based on the principles of electron energy loss spectroscopy. These imaging modalities allow quantitative mapping of specific chemical elements with high sensitivity and spatial resolution. This chapter describes the experimental and computational procedures for elemental mapping in two dimensions as well as a more recent extension to three dimensions, which can reveal quantitative distributions of elements in cells on a macromolecular scale.

An immunostimulating water insoluble ß-glucan of an edible hybrid mushroom: isolation and characterization.

An immunostimulating water-insoluble ß-glucan isolated from hot alkaline extract of the fruiting bodies of an edible somatic hybrid mushroom of Pleurotus florida and Calocybe indica var. APK2 showed significant macrophage, splenocyte, and thymocyte activations. On the basis of total hydrolysis, methylation analysis, and NMR experiments ((1)H, (13)C, DQF-COSY, TOCSY, NOESY, DEPT-135, and HSQC), the repeating unit of the polysaccharide is established.

Structural studies of an immunostimulating gluco-arabinan from seeds of Caesalpinia bonduc.

A water-soluble gluco-arabinan (PS-II, M(W)∼62 kDa) isolated from the alkaline extract of the endosperm of Caesalpinia bonduc showed the presence of T-Glcp, (1→4)-Glcp, (1→2,3)-Glcp, T-Araf, (1→5)-Araf, (1→2,5)-Araf, and (1→2,3,5)-Araf in a relative proportion of approximately 2:2:2:3:2:1:1. The proposed repeating unit of the polysaccharide possessed a branched backbone of two (1→3)-α-D-glucopyranose followed by four (1→5)-α-L-arabinofuranose residues. In case of two (1→3)-α-D-glucopyranose, branching occurs at O-2 by a same residue terminated by another one at O-4 position. Out of four (1→5)-α-l-arabinofuranose residues, one residue is terminated at O-2 and O-3 by two arabinofuranose residues and another one situated at the adjacent position is terminated at O-2 with same residue, and two (1→5)-α-L-arabinofuranose residues are free from branching and located before and after the two branched arabinofuranose residues. This gluco-arabinan molecule and previously reported arabinan showed similar extent of splenocytes and thymocytes stimulation, but arabinan showed appreciable macrophage activations.

A comparison of the cellular actions of polaprezinc (zinc-L-carnosine) and ZnCl2.

AIMS: Zinc supplementation has been proven to be beneficial for the prevention of some health problems. Many zinc supplements are used for medical and nutritional purposes. However, it is difficult to distinguish between them in terms of their cellular actions. We compared the cellular actions of polaprezinc (zinc-l-carnosine) with those of ZnCl(2) in order to determine whether polaprezinc has greater zinc-related actions than ZnCl(2). MAIN METHODS: Cellular actions of polaprezinc and ZnCl(2) were estimated by flow-cytometric techniques with appropriate fluorescent probes in rat thymocytes. KEY FINDINGS: Both agents had almost equal stimulatory effects on the intracellular Zn(2+) level and cellular level of nonprotein thiol in a similar concentration-dependent manner. However, the increase in cell lethality caused by ZnCl(2) under severe oxidative stress was significantly greater than that caused by polaprezinc. SIGNIFICANCE: There are various zinc supplements, for example, zinc gluconate, zinc picolinate, and zinc methionine. However, the differences in their cellular actions have not been elucidated to date. Such studies could distinguish between zinc supplements.

Effects and mechanisms of Cryptotanshinone on rats with adjuvant arthritis.

BACKGROUND: Cryptotanshinone (CT) is the major active constituent of Salvia miltiorrhiza Bunge. The present study was carried out to investigate the effects of CT on rats with adjuvant arthritis (AA). METHODS: AA was induced by the metatarsal footpad injection with complete Freund's adjuvant in male Sprague-Dawley rats. The secondary inflammatory reaction was evaluated by hind paw swelling and the polyarthritis index. Activity of interleukin-1 (IL-1) was detected by the concanavalin A-induced thymocytes proliferation assay. The lymphocytes proliferation and IL-2 production were assayed by 3-(4,5-2dimethylthiazal-2yl)2,5-diphenyltetrazoliumbromide (MTT) and activated mouse splenocytes proliferation, respectively. RESULTS: Intragastric administration of CT (50 and 100 mg/kg) significantly decreased secondary inflammatory reactions and increased the spleen and thymus index. There was a marked immunologic and inflammatory response in the AA model, which was accompanied by the decrease of thymocyte proliferation and IL-2 production as well as the increase of IL-1 production. CT apparently enhanced thymocyte proliferation and decreased IL-1 production in AA rats. CONCLUSION: These results indicate that CT may exert its anti-inflammatory and immunoregulatory effects through inhibiting lymphocyte proliferation and production of pro-inflammatory mediators.