Plasma phospholipids and fatty acid composition differ between liver biopsy-proven nonalcoholic fatty liver disease and healthy subjects.

BACKGROUND: There is growing evidence that nonalcoholic fatty liver disease (NAFLD) is associated with perturbations in liver lipid metabolism. Liver phospholipid and fatty acid composition have been shown to be altered in NAFLD. However, detailed profiles of circulating lipids in the pathogenesis of NAFLD are lacking. OBJECTIVE: Therefore, the objective of the present study was to examine circulating lipids and potential mechanisms related to hepatic gene expression between liver biopsy-proven simple steatosis (SS), nonalcoholic steatohepatitis (NASH) and healthy subjects. SUBJECTS: Plasma phospholipid and fatty acid composition were determined in 31 healthy living liver donors as healthy controls (HC), 26 patients with simple hepatic steatosis (SS) and 20 with progressive NASH. Hepatic gene expression was analyzed by Illumina microarray in a subset of 22 HC, 16 SS and 14 NASH. RESULTS: Concentrations of phosphatidylethanolamine (PE) increased relative to disease progression, HC

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.

Interleukin-10 concentration determined by sandwich enzyme-linked immunosorbent assay is unrepresentative of bioactivity in murine blood.

Two experiments were performed, each using six male and six female C57BL/6J mice collectively ranging from 4 wk to 17 mo of age. Blood was obtained following CO2 anesthesia, and the IL-10 concentration of each serum sample was determined both by sandwich enzyme-linked immunosorbent assay (ELISA) and by bioassay. In the first experiment, mean serum IL-10 immunoactivity was 9.3 pg/ml while the mean bioactivity was 700 times greater, i.e., 6.5 ng/ml. However, the bioassay required sample dilution, which might have released bound cytokine that the ELISA could also detect. In the second experiment, therefore, the ELISA was applied to samples diluted to 20% as for the bioassay. Nevertheless, the immunoassay continued to detect only a small fraction of the serum IL-10 identified by the bioassay (mean values: 32.4 pg/ml vs. 2.6 ng/ml). Although currently the preferred method, the sandwich ELISA is inappropriate for quantification of blood IL-10 concentrations. Moreover, studies of the actions of IL-10 are needed at the concentrations revealed in the blood by bioassay and currently considered supraphysiological.

A comparison of the capacity of six cold-pressed plant oils to support development of acquired immune competence in the weanling mouse: superiority of low-linoleic-acid oils.

The objective of this investigation was to compare, at several levels of intake, the capacity of diverse cold-pressed plant oils to support development of acquired immune competence assessed in vivo in the weanling mouse. Safflower, maize, soyabean, rapeseed, flaxseed and olive oils were selected to represent widely differing 18 : 1n-9, 18 : 2n-6 and 18 : 3n-3 contents, and each oil was fed at three dietary levels (40, 80 and 160 g/kg) as the exclusive source of fat. C57BL/6J mice, ten males and ten females, had free access to each diet for 28 d beginning at 19 d of age. The primary serum haemagglutinin response to sheep red blood cells and the primary cutaneous delayed hypersensitivity response to dinitrochlorobenzene were used to assess humoral and cell-mediated competence respectively, on day 28. A zero-time control group, assessed immunologically at 19 d of age, was also included (n 32). Independently of dietary oil level, flaxseed, rapeseed, olive and soyabean oils supported development of a more vigorous antibody response than safflower (a useful point of reference, being rich in 18 : 2n-6 but low in 18 : 1n-9 and 18 : 3n-3), whereas only flaxseed oil supported development of cell-mediated responsiveness exceeding that of safflower-fed mice. Independently of oil type, development of both immunological indices correlated negatively with intake of 18 : 2n-6, and development of humoral competence varied inversely with dietary oil level. A low content of 18 : 2n-6, perhaps less than 20 g/100 g fatty acids, appears important to the capacity of a plant oil to support development of acquired immune competence in the young.

The CD45RA+ (quiescent) cellular phenotype is overabundant relative to the CD45RA- phenotype within the involuted splenic T cell population of weanling mice subjected to wasting protein-energy malnutrition.

The objective of this investigation was to determine whether an imbalance between naive- and memory-phenotype cells occurs within CD4+ and/or CD8+ splenic T cell subsets in models of protein-energy malnutrition (PEM) which produce wasting disease (loss of approximately 1.6% of body weight per day for 14 d) and profound depression in thymus-dependent immunity. Male and female weanling mice of disparate inbred strains, CBA/J and C57BL/6J, were allocated to the following groups: zero-time control (23 d old and 19 d old, respectively), ad libitum intake of a complete purified diet (19% crude protein, 17 kJ/g gross energy), restricted intake of the complete diet, and (C57BL/6J, only) ad libitum intake of an isocaloric low protein diet (0.6% crude protein). Surface expression of isoforms of CD45, a component of the T cell receptor complex, as well as of the accessory molecule, CD2, were assessed by flow cytometry of splenic mononuclear cell suspensions. Both major T cell subsets in the malnourished groups contained a significantly higher proportion of cells expressing the surface marker, CD45RA, than was found in the spleen cells of the control groups. CD45RA+ (naive-phenotype) T cells represent the extreme of quiescence and stringent activation requirements among thymic lymphocytes. The results provide the first clear evidence of a T cell subset imbalance in PEM which is consistent with depression in acquired immunity and which occurs, apart from antigenic challenge, in a site wherein immune responses take place. The T cell receptor complex may emerge as a focal point of the depressive influence of PEM on the competence of thymic lymphocytes.

The proportion of CD45RA(+)CD62L(+) (quiescent-phenotype) T cells within the CD8(+) subset increases in advanced weight loss in the protein- or energy-deficient weanling mouse.

Male and female C57BL/6J mice, initially 19 d old, had free access to a complete purified diet, were fed this diet in restricted daily quantities, or had free access to a low-protein diet. Three separate studies were conducted with feeding periods of 14, 9 or 6 d (n = 7-8 per dietary group and feeding period; 6 d: restricted intake and age-matched controls only). A zero-time control group (19 d old) was included in each study. Malnourished mice lost approximately 2% of initial body weight daily. Naïve-phenotype (quiescent) CD8(+) T cells of the blood, spleen and mesenteric lymph nodes were identified on the basis of surface coexpression of CD45RA and CD62L. Relative to age-matched controls, the percentage of naïve-phenotype CD8(+) T cells was high in energy-restricted groups after 9 d and 14 d of weight loss and in the protein-restricted groups after 14 d (P < or = 0.05). No ontogenetic change was apparent (age-matched vs. zero-time control). Other studies have demonstrated depression in cell-mediated immune competence in both malnutrition models within the first week of weight loss. An overabundance of quiescent-phenotype T cells within the involuted CD8(+) compartment may contribute to established immune depression but not to its initiation in weight loss pathologies.

Overabundance of CD45RA(+) (quiescent-phenotype) cells within the involuted CD4(+) T-cell population follows initiation of immune depression in energy-deficient weanling mice and reflects involution exclusive to the CD45RA(-) subset.

Previous studies have identified an overabundance of quiescent-phenotype (CD45RA(+)) CD4(+) T cells throughout the lymphoid system of weanling mice at an advanced stage of food intake restriction mimicking marasmus. The objective of this investigation was to determine the timing of this phenomenon relative to the development of depression in cell-mediated immune competence. Two experiments were conducted in which male and female weanling C57BL/6J mice, initially 19 d of age, either were permitted free access to a complete purified diet or were subjected to restricted intake of this diet, producing loss of 1.5-2% of initial body weight daily. In the first experiment, feeding periods of 3, 6, 9, 12 and 14 d were examined, and a zero-time control group (19 d old) was also included. Expression of CD45RA was assessed by flow cytometry in CD4(+) T cells from the blood, spleen and mesenteric lymph nodes. Despite reduction in CD4(+) T-cell numbers, evident in all three lymphoid compartments of the malnourished mice by d 6, energy-restricted mice maintained the numbers of CD4(+)CD45RA(+) T cells at the level found in the zero-time control group. Consequently, the malnourished group exhibited a high percentage of CD4(+) T cells expressing CD45RA by d 9 in the blood and mesenteric nodes and by d 12 in the spleen. In the second study, malnourished and age-matched control groups were sensitized to sheep red blood cells on d 3 and energy-restricted mice exhibited depression in the delayed hypersensitivity response to this antigen when assessed on d 9 after challenge 24 h previously. Energy deficiency pathology includes a shift toward CD4(+) T cell quiescence that may contribute to ongoing immunodepression without being involved in its initiation. Remarkably, this imbalance develops because involution of the CD4(+) subset in the energy-deficient mice is confined to the CD45RA(-) population.