Dietary intervention studies on the phosphoglyceride fatty acids and electrophoretic mobility of erythrocytes in multiple sclerosis

Polyunsaturated fatty acids in the pathogenesis and treatment of multiple sclerosis

Epidemiological, biochemical, animal model and clinical trial data described in this overview strongly suggest that polyunsaturated fatty acids, particularly n-6 fatty acids, have a role in the pathogenesis and treatment of multiple sclerosis (MS). Data presented provides further evidence for a disturbance in n-6 fatty acid metabolism in MS. Disturbance of n-6 fatty acid metabolism and dysregulation of cytokines are shown to be linked and a "proof of concept clinical trial" further supports such a hypothesis. In a randomised double-blind, placebo controlled trial of a high dose and low dose selected GLA (18:3n-6)-rich oil and placebo control, the high dose had a marked clinical effect in relapsing-remitting MS, significantly decreasing the relapse rate and the progression of disease. Laboratory findings paralleled clinical changes in the placebo group in that production of mononuclear cell pro-inflammatory cytokines (TNF-alpha, IL-1beta) was increased and anti-inflammatory TGF-beta markedly decreased with loss of membrane n-6 fatty acids linoleic (18:2n-6) and arachidonic acids (20:4n-6). In contrast there were no such changes in the high dose group. The improvement in disability (Expanded Disability Status Scale) in the high dose suggests there maybe a beneficial effect on neuronal lipids and neural function in MS. Thus disturbed n-6 fatty acid metabolism in MS gives rise to loss of membrane long chain n-6 fatty acids and loss of the anti-inflammatory regulatory cytokine TGF-beta, particularly during the relapse phase, as well as loss of these important neural fatty acids for CNS structure and function and consequent long term neurological deficit in MS.

Fatty acids, the immune response, and autoimmunity: a question of n-6 essentiality and the balance between n-6 and n-3

The essentiality of n-6 polyunsaturated fatty acids (PUFA) is described in relation to a thymus/thymocyte accretion of arachidonic acid (20:4n-6, AA) in early development, and the high requirement of lymphoid and other cells of the immune system for AA and linoleic acid (1 8:2n-6, LA) for membrane phospholipids. Low n-6 PUFA intakes enhance whereas high intakes decrease certain immune functions. Evidence from in vitro and in vivo studies for a role of AA metabolites in immune cell development and functions shows that they can limit or regulate cellular immune reactions and can induce deviation toward a T helper (Th)2-like immune response. In contrast to the effects of the oxidative metabolites of AA, the longer-chain n-6 PUFA produced by gamma-linolenic acid (18:3n-6, GLA) feeding decreases the Th2 cytokine and immunoglobulin (Ig)G1 antibody response. The n-6 PUFA, GLA, dihomo-gamma-linolenic acid (20:3n-6, DHLA) and AA, and certain oxidative metabolites of AA can also induce T-regulatory cell activity, e.g., transforming growth factor (TGF)-beta-producing T cells; GLA feeding studies also demonstrate reduced proinflammatory interleukin (IL)-1 and tumor necrosis factor (TNF)-alpha production. Low intakes of long-chain n-3 fatty acids (fish oils) enhance certain immune functions, whereas high intakes are inhibitory on a wide range of functions, e.g., antigen presentation, adhesion molecule expression, Th1 and Th2 responses, proinflammatory cytokine and eicosanoid production, and they induce lymphocyte apoptosis. Vitamin E has a demonstrable critical role in long-chain n-3 PUFA interactions with immune functions, often reversing the effects of fish oil. The effect of dietary fatty acids on animal autoimmune disease models depends on both the autoimmune model and the amount and type of fatty acids fed. Diets low in fat, essential fatty acid deficient (EFAD), or high in long-chain n-3 PUFA from fish oils increase survival and reduce disease severity in spontaneous autoantibody-mediated disease, whereas high-fat LA-rich diets increase disease severity. In experimentally induced T cell-mediated autoimmune disease, EFAD diets or diets supplemented with long-chain n-3 PUFA augment disease, whereas n-6 PUFA prevent or reduce the severity. In contrast, in both T cell- and antibody-mediated autoimmune disease, the desaturated/elongated metabolites of LA are protective. PUFA of both the n-6 and n-3 families are clinically useful in human autoimmune-inflammatory disorders, but the precise mechanisms by which these fatty acids exert their clinical effects are not well understood. Finally, the view that all n-6 PUFA are proinflammatory requires revision, in part, and their essential regulatory and developmental role in the immune system warrants appreciation.

Post-natal modulation of heart and liver phosphoglyceride fatty acids in pups

BACKGROUND

Maternal dietary fats alter tissue fatty acids of the fetus and suckling pups. However, the possible change in tissue composition in response to the high oxygen tension extrauterine milieu independent of diet is not well understood.

METHODS

We have compared the fatty acids of heart and liver choline (CPG) and ethanolamine (EPG) phosphoglycerides of rat offspring at birth and post-natal day 15. Sprague-Dawley rats were fed a breeding diet prior to mating, pregnancy and lactation. A proportion of each litter was sacrificed and the liver and heart were obtained for analysis. Changes in fatty acid composition specific to tissue (heart and liver) and phosphoglyceride (CPG and EPG) occurred post-natally.

RESULTS

Relative levels of palmitate and oleate decreased and those of stearate increased in both the heart and liver phosphoglycerides of the suckling pups. There was a reduction in arachidonate/linoleate ratio primarily due to the increase in linoleic acid. With the exception in the heart EPG, the levels of arachidonic acid did not decrease concomitantly. Although the fatty acid composition of the diet did not change between pregnancy and lactation, docosahexaenoic and total n-3 increased in heart CPG and EPG and liver CPG of the suckling pups. Evidently, membrane fatty acid modulation, independent of maternal dietary fat, occurs in the extrauterine environment. It seems to favour the accretion of linoleic, arachidonic, docosahexaenoic and total n-3 fatty acids.

CONCLUSION

Since there appears to be some parallel between the very preterm human neonate and rat pups with regard to nutrient store at birth and the neonatal developmental time window, our results may have relevance for the understanding of fatty acid metabolism and turnover in the human neonate.

Prevention of experimental autoimmune encephalomyelitis in Lewis rats by a novel fungal source of gamma-linolenic acid

The effects of oral administration of linoleic- and gamma-linolenic-acid-rich oils on the clinical and histopathological manifestations of experimental autoimmune encephalomyelitis (EAE) were investigated in Lewis rats 7 d post-inoculation. gamma-Linolenic-acid-rich fungal (Mucor javanicus) oil at 500 mg/kg body weight abrogated clinical and histological signs of EAE although at doses of 200 and 1000 mg/kg body weight it was only effective in delaying the onset of clinical disease. Linoleic-acid-rich safflower-seed (Carthamus tinctorius) oil at 500, 750 and 1000 mg/kg body weight decreased the severity of clinical EAE disease in a dose-dependent manner. The effects in healthy animals of orally administered gamma-linolenic-acid-rich fungal oil (500 mg/kg body weight) and linoleic-acid-rich safflower-seed oil (1000 mg/kg body weight) on splenic lymphocyte proliferative responses to the T-cell mitogen concanavalin-A (Con A), membrane fatty acid composition and lymphocyte sub-sets were also studied. Both treatments enhanced the T-cell proliferative response to Con A. There was no significant effect on the proportion of splenic CD8+ or CD4+ lymphocytes. Compositional studies on splenic phosphoglyceride fatty acids of oil-treated animals suggest the above responses were associated with increases in spleen dihomo-gamma-linolenic and arachidonic acids.

Erythrocyte fatty acids in multiple sclerosis

Analysis of the fatty acids in the erythrocyte lipid of multiple sclerosis patients in Italy gave no indication of any difference in composition compared with that of a healthy control group. Supplementation of the diet of another group of similar patients with polyunsaturated fatty acids led to increases in the erythrocyte levels of linoleate and docosahexaenoate, with concomitant falls in oleate and elaidate. Levels of fatty acids such as lignocerate and nervonate that are found predominantly in sphingomyelin were similar in all 3 groups.