Bruce N. Ames

Vitamin E forms inhibit IL-13/STAT6-induced eotaxin-3 secretion by up-regulation of PAR4, an endogenous inhibitor of atypical PKC in human lung epithelial cells☆

Eotaxin-3 (CCL-26), a potent chemokine for eosinophil recruitment and contributing significantly to the pathogenesis of asthma, is secreted by lung epithelial cells in response to T helper 2 cytokines including interleukin 13 (IL-13). Here we showed that vitamin E forms, but not their metabolites, differentially inhibited IL-13-stimulated generation of eotaxin-3 in human lung epithelial A549 cells. The relative inhibitory potency was γ-tocotrienol (γ-TE) (IC50 ~15 μM)>γ-tocopherol, δ-tocopherol (IC50 ~25-50 μM)>α-tocopherol. Consistent with suppression of eotaxin, γ-TE treatment impaired IL-13-induced phosphorylation of STAT6, the key transcription factor for activation of eotaxin expression, and consequently blocked IL-13-stimulated DNA-binding activity of STAT6. In search of the upstream target of γTE by using inhibitor and siRNA approaches, we discovered that the atypical protein kinase C (aPKC) signaling, instead of classical PKC, p38 MAPK, JNK or ERK, played a critical role in IL-13-stimulated eotaxin generation and STAT6 activation. While showing no obvious effect on aPKC expression or phosphorylation, γ-TE treatment resulted in increased expression of prostate-apoptosis-response 4 (PAR4), an endogenous negative regulator of aPKCs. Importantly, γ-TE treatment led to enhanced formation of aPKC/PAR4 complex that is known to reduce aPKC activity via protein-protein crosstalk. Our study demonstrated that γ-TE inhibited IL-13/STAT6-activated eotaxin secretion via up-regulation of PAR4 expression and enhancement of aPKC-PAR4 complex formation. These results support the notion that specific vitamin E forms may be useful anti-asthmatic agents.

A combination of aspirin and gamma-tocopherol is superior to that of aspirin and alpha-tocopherol in anti-inflammatory action and attenuation of aspirin-induced adverse effects.

Nonsteroidal anti-inflammatory drugs such as aspirin are used for pain relief and chemoprevention against cancer, but frequently cause gastric mucosal injury. We examined whether combinations of aspirin and alpha-tocopherol (alphaT) or aspirin and gamma-tocopherol (gammaT), with alphaT and gammaT being the two major forms of vitamin E, are better anti-inflammatory agents than aspirin alone, and whether these combinations alleviate aspirin-associated side effects. In the carrageenan-induced air-pouch inflammation model in the rat, aspirin (150 mg/kg) or a combination of aspirin and gammaT (33 mg/kg) inhibited proinflammatory prostaglandin E(2) (PGE(2)) by 70% (P<.02) at the inflammation site 6 h after inflammation was initiated. However, at 18 h, only the combination decreased exudate volume (15%; P<.05) and showed modest inhibition of PGE(2) (40%; P<.07) and lactate dehydrogenase activity (30%; P=.07) in the fluid collected at the inflammation site. gammaT, but not alphaT, spared aspirin-induced reduction in food intake, partially reversed aspirin-depressed gastric PGE(2) and attenuated stomach lesions. Surprisingly, the combination of aspirin and alphaT (33 mg/kg) did not show more benefits than aspirin alone, but worsened gastric injury and food intake reduction. Our study demonstrated that a combination of aspirin and gammaT, but not a combination of aspirin and alphaT, has some advantage over aspirin alone in terms of anti-inflammatory effects and attenuation of aspirin-induced adverse effects. This combination may be useful in complementing aspirin in the treatment of chronic inflammatory conditions and cancer.

Increased leucocyte apoptosis in transfused β-thalassaemia patients

This exploratory study assessed apoptosis in peripheral blood leucocytes (PBL) from β‐thalassaemia patients receiving chronic transfusions and chelation therapy (deferasirox or deferoxamine) at baseline, 1, 6, and 12 months. At baseline, thalassaemic PBLs presented 50% greater levels of Bax (BAX), 75% higher caspase‐3/7, 48% higher caspase‐8 and 88% higher caspase‐9 activities and 428% more nucleosomal DNA fragmentation than control subjects. Only neutrophils correlated significantly with apoptotic markers. Previously, we showed that over the treatment year, hepatic iron declined; we now show that the ratio of Bax/Bcl‐2 (BCL2), (−27·3%/year), and caspase‐9 activity (−13·3%/year) declined in both treatment groups, suggesting that chelation decreases body iron and indicators of PBL apoptosis.

DNA Damage to Sperm from Micronutrient Deficiency May Increase the Risk of Birth Defects and Cancer in Offspring

Deficiency of vitamins B12, folic acid, B6, niacin, C, or E, or iron, or zinc, appears to mimic radiation in damaging DNA by causing single- and double-strand breaks, oxidative lesions, or both (1). Oxidation is a major contributor to both cancer and aging (1–11). The percentage of the United States population that has a low intake (<50% of the RDA) for each of these eight micronutrients ranges from 2−20+%; half of the population may be deficient in at least one (1). We have shown that folate deficiency breaks chromosomes due to massive incorporation of uracil in human DNA (4 million/cell) with subsequent single-strand breaks in DNA formed during base excision repair: two nearby single-strand breaks on opposite strands cause the chromosome to fall apart. Folate (10% of United States), vitamin B12 (14% elderly), and B6 (10% of United States) deficiencies all cause high uracil in human DNA. Micronutrient deficiency may explain, in good part, why the quarter of the population that eats the fewest fruits and vegetables (5 portions a day is advised) has about double the cancer rate for most types of cancer when compared to the quarter with the highest intake.