Effects of dietary fish oil on survival rate, plasma amino acid pattern, and inflammatory-related mediators in diabetic rats with sepsis.

This study was designed to investigate the effects of dietary fish oil on survival rates, plasma amino acid profiles, and inflammatory-related mediators in diabetic rats with sepsis. Diabetes mellitus (DM) was induced in rats by streptozotocin. The DM rats were maintained for 4 weeks on medium fat (10%, w/w) diets containing either fish oil or safflower oil. After that, sepsis was induced by cecal ligation and puncture (CLP). There were 2 groups in this study: fish oil sepsis group (FOS) and safflower oil sepsis group (SOS). The survival rate was observed after CLP. Also, changes of the amino acid pattern as well as interleukin (IL)-1 beta, tumor necrosis factor (TNF)-alpha, prostaglandin (PG) E(2)at 6, 12, and 24 h after CLP were investigated. The results demonstrated that survival rates were not significantly different between the 2 groups. Plasma arginine levels were significantly lower in sepsis groups than that in the DM-chow group, regardless of whether the diabetic rats were fed fish oil or safflower oil. No significant differences were observed in plasma valine, leucine, isoleucine, glutamine, or arginine concentrations between the FOS and SOS groups at different time points. Concentrations of IL-1 beta in peritoneal lavage fluid (PLF) at 6 h and TNF-alpha at 6 h as well as at 12 h after CLP in the FOS group were significantly higher than those in the SOS group. PGE(2)levels in PLF, by contrast, were lower in the FOS group at 6 and 12 h after CLP than in the SOS group. These results suggest that differences in IL-1 beta, TNF-alpha, and PGE(2)levels in PLF in the early period of sepsis did not influence the survival rates and plasma amino acid profiles of the FOS and SOS groups. Compared with safflower oil, feeding diabetic rats with fish oil had no beneficial effects on survival rates and muscle protein breakdown. The immunologic impact of dietary n-3 polyunsaturated fatty acids on diabetic rats with sepsis requires further investigation.

The effect of adding fish oil to parenteral nutrition on hepatic mononuclear cell function and survival after intraportal bacterial challenge in mice.

BACKGROUND: Parenteral nutrition (PN) is indispensable for meeting caloric and substrate needs of patients who cannot receive adequate amounts of enteral nutrition; however, PN impairs hepatic immunity. We examined the effects of ω-3 and -6 polyunsaturated fatty acids, added individually to fat-free PN, on hepatic immunity in a murine model. We focused on serum liver enzymes, cytokine production, histopathology, and the outcomes after intraportal bacterial challenge. METHODS: Male Institute of Cancer Research mice were randomized into 4 groups; ad libitum chow (CHOW), fat-free PN (FF-PN), PN + fish oil (FO-PN), or PN + safflower oil (SO-PN). After the mice had been fed for 5 days, hepatic mononuclear cells (MNCs) were isolated. The number of MNCs was counted and cytokine production (tumor necrosis factor [TNF]-α and interleukin [IL]-10) by hepatic MNCs in response to lipopolysaccharide (LPS) was measured. Blood samples were analyzed for hepatobiliary biochemical parameters. Moreover, 1.0 × 10(7) pseudomonas aeruginosa were delivered by intraportal injection. Survival and histology were examined. RESULTS: Hepatic MNC numbers were significantly less in the FO-PN and FF-PN than in the CHOW group, whereas the SO-PN group showed moderate recovery of hepatic MNC numbers. The CHOW, FO-PN, and SO-PN groups showed LPS dose-dependent increases in TNF-α levels. These increases were blunted in the FF-PN group. IL-10 levels were increased LPS dose-dependently in the CHOW and FO-PN groups, but no marked changes were observed with LPS stimulation in the SO-PN and FF-PN groups. Plasma levels of aspartate aminotransferase, alanine aminotransferase, and alkaline phosphatase were significantly greater in the FF-PN than in the FO- and SO-PN and CHOW groups. The FO-PN group showed significantly improved survival compared with the SO-PN and FF-PN groups, showing essentially no morphologic hepatic abnormalities. CONCLUSION: Addition of fish oil to PN was advantageous in terms of reversing PN-induced deterioration of hepatic immunity, as reflected by altered cytokine production. Fish oil administration was also useful for preventing PN-induced hepatobiliary dysfunction. These changes seem to result in better survival and to protect against severe tissue damage after intraportal bacterial challenge. This therapy may have the potential to ameliorate PN-induced impairment of host immunity and thereby decrease morbidity and mortality.

Cold-pressed flaxseed oil reverses age-associated depression in a primary cell-mediated adaptive immune response in the mouse.

The objective of this investigation was to determine the influence of flaxseed oil on responses representative of primary humoral and cell-mediated adaptive immune competence in immunosenescent mice. Male and female C57BL/6J mice, 85 weeks old, were randomized between two complete purified diets differing only in oil source (cold-pressed safflower or flaxseed). After 8 weeks, humoral competence was assessed in six mice per group as the serum haemagglutinin titre to sheep red blood cells (SRBC) and cell-mediated competence was assessed, in an additional six mice per group, as the delayed hypersensitivity response to SRBC. A zero-time control group (88 weeks old) and a young adult positive control group (12 weeks old) were each tested similarly (six per immune response), revealing age-related depression in both antibody and cell-mediated competence at 88 weeks of age. After the 8-week experimental period, the antibody response of the two test groups of geriatric mice remained below the young adult level (P=0.04) and the cell-mediated response of the safflower oil group also continued to exhibit age-related depression (20 % of young adult level, P=0.0002). By contrast, the anti-SRBC delayed hypersensitivity response of the flaxseed group no longer differed from the response of the young adults but exceeded that of the safflower and zero-time control senescent groups (P=0.0002). Depression in primary cell-mediated competence, the most outstanding aspect of immunosenescence, can be addressed by means of a dietary source of 18 : 3n-3 without longer-chain PUFA.