Toxicological evaluation of pomegranate seed oil.

In this manuscript, the toxicology and safety of pomegranate seed oil (PSO) was evaluated by in vitro (Ames, chromosomal aberration), and in vivo toxicity tests (acute toxicity and 28-day toxicity in Wistar rats). No mutagenicity of PSO was observed in the absence and presence of metabolic activation up to precipitating concentrations of 5000 microg/plate (Ames test) or 333 microg/ml (chromosome aberration test). The acute oral toxicity study revealed no significant findings at 2000 mg PSO/kg body weight. In the 28-day dietary toxicity study PSO was dosed at concentrations of 0, 10,000, 50,000 and 150,000 ppm, which resulted in a mean intake of 0-0, 825-847, 4269-4330 and 13,710-14,214 mg PSO/kg body weight per day in males-females, respectively. At 150,000 ppm dietary exposure to PSO, a much higher dose than the level of PSO that elicits antidiabetic and anti-inflammatory efficacy, increased hepatic enzyme activities determined in plasma (aspartate, alanine aminotransferase and alkaline phosphatase) and increased liver-to-body weight ratios were observed. However, these effects might be the result of a physiological response to exposure to a very high level of a fatty acid which is not part of the normal diet, and are most likely not toxicologically relevant. The no observable adverse effect level (NOAEL) was 50,000 ppm PSO (=4.3 g PSO/kg body weight/day).

Long-term influence of lipid nutrition on the induction of CD8(+) responses to viral or bacterial antigens.

Porcine CD8(+) lymphocytes are critical for the development of cellular immune responses to bacterial (i.e. CD8alphaalpha(+)) and viral (i.e. CD8alphabeta(+) lymphocytes) pathogens. Vaccination and challenge modulate the kinetics of appearance of CD8(+) cells in peripheral blood. In addition to antigen-mediated modulation, nutritional modulation can also influence cell-mediated immunity. We had previously observed that diets supplemented with a mixture of conjugated linoleic acid (CLA) isomers expanded porcine CD8(+) peripheral blood mononuclear cells (PBMC). The present study aimed to investigate the influence of prior consumption of a nutraceutical, (i.e. dietary CLA) on phenotypes and effector functions of porcine PBMC following immunization with a bacterin or a modified-live viral vaccine. It was demonstrated that the effects of dietary CLA on immune cell phenotype (i.e. numbers of CD8alphabeta(+) cells) persisted after the compound was withdrawn from the diet (i.e. 67 days), whereas effector functions (i.e. antigen-stimulated proliferation and cytotoxicity) disappeared earlier (i.e. 25 days). Specifically, numbers of CD8alphabeta(+) PBMC in pigs that had been fed diets supplemented with CLA were greater than in pigs fed control (i.e. isoenergetic and unsupplemented) diets, regardless of the vaccination treatment. Furthermore, prior dietary CLA supplementation interacted with viral immunization (i.e. modified-live pseudorabies virus (PRV) vaccine) by enhancing both pseudorabies-specific proliferative responses of CD8alphabeta(+) PBMC and granzyme activities of PBMC.

Dietary conjugated linoleic acid modulates phenotype and effector functions of porcine CD8(+) lymphocytes.

In vivo vaccination and challenge studies have demonstrated that CD8(+) lymphocytes are essential for the development of cell-mediated protection against intracellular pathogens and neoplastic cells. Depletion of peripheral blood CD8(+) cells interferes with clearance of viruses and intracellular fungi, induction of delayed type hypersensitivity responses and antitumoral activity. In contrast to humans or mice, porcine peripheral CD8(+) lymphocytes are characterized by a heterogeneous expression pattern (i.e., CD8alphabeta and CD8alphaalpha) that facilitates the study of distinctive traits among minor CD8(+) cell subsets. A factorial (2 x 2) arrangement within a split-plot design, with 16 blocks of two littermate pigs as the experimental units for immunization treatment (i.e., unvaccinated or vaccinated with a proteinase-digested Brachyspira hyodysenteriae bacterin) and pig within block as the experimental unit for dietary treatment (soybean oil or conjugated linoleic acid) were used to investigate the phenotypic and functional regulation of CD8(+) cells by dietary conjugated linoleic acid (CLA). Dietary CLA supplementation induced in vivo expansion of porcine CD8(+) cells involving T-cell receptor (TCR)gammadeltaCD8alphaalpha T lymphocytes, CD3(-)CD16(+)CD8alphaalpha (a porcine natural killer cell subset), TCRalphabetaCD8alphabeta T lymphocytes and enhanced specific CD8(+)-mediated effector functions (e.g., granzyme activity). Expansion of peripheral blood TCRalphabetaCD8alphabeta cells was positively correlated (r = 0.89, P < 0.01) with increased percentages of CD8alphabeta(+) thymocytes. Functionally, CLA enhanced the cytotoxic potential of peripheral blood lymphocytes and proliferation of TCRgammadeltaCD8alphaalpha cells. Collectively, these results indicate that dietary CLA enhances cellular immunity by modulating phenotype and effector functions of CD8(+) cells involved in both adaptive and innate immunity.

Effects of dietary conjugated linoleic acid in nursery pigs of dirty and clean environments on growth, empty body composition, and immune competence.

Early-weaned pigs (n = 64) averaging 5.3 +/- 0.3 kg and distributed into two environments (dirty and clean) were used to evaluate effects of conjugated linoleic acid (CLA) on growth performance, immune competence, and empty body composition. A factorial (2 x 4) arrangement within a split-plot design, with four littermate pigs as the experimental unit for the environment, pig within litter as the experimental unit for dietary treatment, and d-0 body weight used as covariate, were used in data analysis. Diets were formulated to contain CLA at 0, 0.67, 1.33, or 2% and to exceed the NRC (1988) nutrient needs of pigs. Animals were given ad libitum access to feed for 7 wk in three phases (I, 1 to 2; II, 3 to 5; and III, 6 to 7 wk). Within phases, diets were isocaloric and isonitrogenous. In Phase I, as dietary CLA concentration increased, ADG and ADFI decreased linearly (P < 0.05 and P < 0.02, respectively). In Phase II, upon adaptation to dietary CLA supplementation, ADG increased quadratically (603, 623, 622, and 548 g/d; P < 0.01), ADFI decreased linearly (873, 840, 867, and 717 g/d; P < 0.02) and gain:feed ratio tended to increase linearly (691, 742, 715, and 763; P < 0.07). In Phase III, no differences in growth performance were attributed to either dietary or environmental treatments. The poor health status associated with the dirty environment induced a growth suppression; pigs in the clean room had a greater cumulative ADG (P < 0.01) and ADFI (P < 0.01) than pigs in the dirty room. In Phase I, lower plasma urea nitrogen levels observed in pigs found in the dirty room (P < 0.03) indicated a lower protein intake caused by a lower ADFI. The effects of dietary CLA on peripheral phenotypic profiles of lymphoytes did not appear until d 42. However, as indicated by the growth suppression of pigs in the dirty room, the negative effects of the environmental challenge on pig health and growth had already appeared during phase I. On d 42, CLA induced a linear increase in percentages of CD8+ lymphocytes (21.7, 22.3, 28.0, and 32.7%; P < 0.001). These data suggest that a 42-d dietary CLA supplementation preceding a disease challenge could have prevented disease-associated growth suppression. Also, CLA-mediated amelioration of particular infectious diseases will depend on which CD8+ T cell subset (i.e., CD8alphaalpha-immunoregulatory or CD8alphabeta-cytotoxic) is most influenced by dietary CLA supplementation.