Trans fatty acids and atopic eczema/dermatitis syndrome: The relationship with a free radical cis-trans isomerization of membrane lipids

The formation of trans FA residues in membrane phospholipids may be due to a free radical-catalyzed isomerization process occurring to the cis unsaturated FA moieties. Radical stress is well documented in inflammatory processes of atopic diseases, but no data are yet available about a possible association with trans FA detected in these patients. We investigated the presence of trans lipid isomers in the erythrocyte and T-lymphocyte membranes of 26 children affected by atopic eczema/dermatitis syndrome (AEDS). Trans lipid isomers were found in both cell membranes, up to a total content of 2.7 and 4.9% of the FA composition, respectively. By using the geometrical trans lipid library derived from in vitro models of thiyl radical-catalyzed isomerization, oleic and arachidonic acid isomers were detected. The statistical significance was evaluated by comparison with an age-matched control group. These results suggest the role of an endogenous free radical isomerization path occurring to membrane unsaturated lipids, complementary to the dietary contribution, which can be involved in the lipid impairment in AEDS. This study contributes to lipidomic research regarding the double bond structure and the influence of a geometrical change of membrane lipids in physiology and diseases

Altered lipid cell membrane profile in children affected by atopic dermatitis

Rationale An abnormal essential fatty acid (EFAs) metabolism and a higher unsaturated trans FA (TFA) levels have been associated with allergy suggesting a link between fatty acid (FA) structures and atopic diseases. The aim of the present study was to correlate the atopic status with FA profile and TFA presence in cell membrane. Methods We studied the erythrocyte and T lymphocyte membranes obtained from 10 children affected by atopic dermatitis (AD). Total phospholipid fractions were analyzed by an innovative protocol made of two parallel gas chromatography (GC) analysis which include the cis/trans isomer identification of FA. Results In all patients the saturated/monounsaturated FA (SFA/MUFA) ratio was higher than normal range (1.7-2). The percentage of arachidonate 20:4 FA was normal but, in 3 patients, it was replaced by 20:3. The GC profile of C20 FA, compared with the profile of arachidonate isomerization, showed the presence of trans isomers at high levels. Moreover, trans isomer of oleic acid residues was also found in 50% of the patients and 20:5 (EPA) and 22:6 (DHA) FA were very low or absent in all the patients. Conclusions In erythrocyte and T cell membranes of our AD children a serious impairment of lipid metabolism was observed, consistent with a reduced rate of activity of delta 6 desaturase. The altered SFA/MUFA ratio together with the higher percentage of the trans isomeric forms might affect membrane structure or fluidity and consequently lead to an alteration of the immune receptor complexes within the lipid microdomains (rafts)