Cell Phospholipid Fatty Acid Composition Research Articles

The fatty acid imbalance of cystic fibrosis exists at birth independent of feeding in pig and ferret models.

Persons with cystic fibrosis (CF) exhibit a unique alteration of fatty acid composition, marked especially among polyunsaturates by relative deficiency of linoleic acid and excess of Mead acid. Relative deficiency of docosahexaenoic acid is variably found. However, the initial development of these abnormalities is not understood. We examined fatty acid composition in young CF ferrets and pigs, finding abnormalities from the day of birth onward including relative deficiency of linoleic acid in both species. Fatty acid composition abnormalities were present in both liver and serum phospholipids of newborn CF piglets even prior to feeding, including reduced linoleic acid and increased Mead acid. Serum fatty acid composition evolved over the first weeks of life in both non-CF and CF ferrets, though differences between CF and non-CF persisted. Although red blood cell phospholipid fatty acid composition was normal in newborn animals, it became perturbed in juvenile CF ferrets including relative deficiencies of linoleic and docosahexaenoic acids and excess of Mead acid. In summary, fatty acid composition abnormalities in CF pigs and ferrets exist from a young age including at birth independent of feeding and overlap extensively with the abnormalities found in humans with CF. That the abnormalities exist prior to feeding implies that dietary measures alone will not address the mechanisms of imbalance.

Correction to: Different effects of γ-linolenic acid (GLA) supplementation on plasma and red blood cell phospholipid fatty acid composition and calcium oxalate kidney stone risk factors in healthy subjects from two race groups with different risk profiles pose questions about the GLA-arachidonic acid-oxaluria metabolic pathway: pilot study.

The authors would like to add the following paragraph in the acknowledgement section of the original version of the paper.

Different effects of γ-linolenic acid (GLA) supplementation on plasma and red blood cell phospholipid fatty acid composition and calcium oxalate kidney stone risk factors in healthy subjects from two race groups with different risk profiles pose questions about the GLA-arachidonic acid-oxaluria metabolic pathway: pilot study.

Fatty acid (FA) composition of phospholipids in plasma and red blood cells (RBC) can influence calciuria, oxaluria and renal stone formation. In this regard, the ratio of arachidonic acid (AA) and its precursor linoleic acid (LA) appears to be important. Administration of γ-linolenic acid (GLA) has been shown to increase the concentration of dihomo-gamma linoleic acid (DGLA) relative to AA indicating that it may attenuate biosynthesis of the latter. Such effects have not been investigated in race groups having difference stone occurrence rates. Black (B) and white (W) healthy males ingested capsules containing linoleic acid (LA) and GLA, for 30days. Plasma and RBC total phospholipid (TPL) FA profiles, serum and 24h urine biomarkers of hypercalciuria and urinary stone risk factors were determined on days 0 and 30. Data were tested for statistical significance using GraphPadInstat version 3.02. Concentration and percentage content of DGLA in plasma TPL increased in W but not in B. Arachidonic acid (AA) did not change in either group. There was no change in calcium excretion in either group but oxalate and citrate excretion increased in W. We suggest that elongation of GLA to DGLA may occur more rapidly than desaturation of DGLA to AA in W and that depressed activity of the enzyme elongase may occur in B. Calciuric and citraturic effects may be dependent on the quantity of LA or on the mass ratio of LA/GLA in the FA supplement. Questions about the mooted DGLA-AA-oxaluria pathway arise. We speculate that there exists a potential for using GLA as a conservative treatment for hypocitraturia. The observation of different responses in B and W indicates that such differences may play a role in stone formation and prevention.

Dietary fat and insulin sensitivity

Insulin resistance is associated with a number of metabolic abnormalities that increase the risk of developing coronary heart disease. Dietary fat has been linked with insulin resistance, with alterations in the quality as opposed to the quantity of dietary fat now thought be more important in instigating improvements in insulin resistance. The aim of this work was to investigate the effect of alterations in the dietary fat intakes of middle-aged men (n = 32) on the insulin sensitivity of glucose disposal and postprandial lipid metabolism and to explore the mechanistic links between these insulin responsive pathways. Three separate dietary interventions were conducted; the first involved an increase in the intake of n-3 polyunsaturated fat, the second a decrease in saturated fat and an increase in carbohydrate and the third a decrease in saturated fat and an increase in monounsaturated fat intake. Compliance was monitored by the measurement of red blood cell phospholipid fatty acid composition, postprandial lipid metabolism was measured over 9 hours following a high-fat breakfast (80 g fat), and insulin resistance was measured using the short insulin tolerance test. The results of the study showed that while insulin sensitivity was inversely correlated with red blood cell saturated fatty acid concentration at baseline, the insulin sensitivity of glucose disposal was unaffected by any of the dietary interventions conducted. In measurements of postprandial lipaemia, improvements were observed following the low-saturated fat / high-monounsaturated fat diet and the n-3 polyunsaturated enriched diet, however the low-saturated fat/ high-carbohydrate diet was associated with a worsening of postprandial lipaemia through an increase in the concentrations of triglyceride-rich-lipoproteins. Changes in fasting biochemical measurements were most evident in the low-saturated / high-monounsaturated diet, with an 11 % reduction in total cholesterol and a 15.4 % reduction in fasting triglycerides. There were no observed changes in the activity levels or the gene expression of lipoprotein lipase. There was an unexpected positive association between the degree of insulin sensitivity and the extent of postprandial lipaemia, indicating that the link between these pathways is complex and warrants further investigation. Overall this work supports the view that dietary guidelines should be directed towards a change in the composition of fat, to a lower saturated fat intake, a higher monounsaturated fat intake and a lower n-6 : n-3 ratio through an increase in the intake of long chain n-3 polyunsaturated fatty acids.

A randomised control trial in schoolchildren showed improvement in cognitive function after consuming a bread spread, containing fish flour from a marine source

Background In humans, n-3 long-chain polyunsaturated fatty acids play a well-documented role in brain development and function. Docosahexaenoic acid and arachidonic acid are major structural components of the brain and a deficiency thereof may bring about changes in the behaviour domains of the brain. Objective This trial investigated the effect of an experimental fish-flour bread spread rich in n-3 long-chain polyunsaturated fatty acids, on cognition of children (7–9 yr). Design Subjects ( n=183) were randomly assigned to an experimental ( n=91) and control group ( n=92), receiving either the fish-flour spread or a placebo spread for 6 months in a single-blind study. Plasma and red blood cell phospholipid fatty acid composition and cognition were measured at baseline and post-intervention. Results After the intervention, eicosapentaenoic and docosahexaenoic acid levels were significantly higher in the experimental group compared to the control group ( p< 0.0001). Significant intervention effects were also observed for the Hopkins Verbal Learning Test Recognition (estimated effect size: 0.80; 95% confidence interval (CI): 0.15; 1.45) and Discrimination Index (estimated effect size: 1.10; 95% CI: 0.30; 1.91), as well as the S pelling test (estimated effect size: 2.81; 95% CI: 0.59; 5.02) by both per protocol and intention to treat analyses. A marginally significant ( p=0.0646) effect was observed for the Reading test (estimated effect size: 2.21; 95% CI: −0.14; 4.56) only in the per protocol analysis. Conclusion This study suggests improvement of verbal learning ability and memory of children when supplemented with a fish-flour spread rich in n-3 long-chain polyunsaturated fatty acids.

Serum, cheek cell and breast milk fatty acid compositions in infants with atopic and non‐atopic eczema

The major theory implicating diet with allergic diseases is associated with altered food consumption and subsequent changes in fatty acid composition. To investigate fatty acid compositions among infants with atopic and non-atopic eczema and healthy infants and to evaluate the expediency of non-invasive cheek cell phospholipid fatty acid composition as a marker in patients with eczema. Diagnosis of eczema in infants was confirmed clinically and by positive (atopic eczema, n=6) or negative (non-atopic eczema, n=6) skin prick testing in comparison with controls (n=19). The fatty acid compositions of infant cheek cell and serum phospholipids and breast milk total lipids were analysed by gas chromatography. The distinction between atopic and non-atopic eczema was manifested in cheek cell phospholipids as linoleic acid (14.69 (13.67-15.53)% of total fatty acids; the median (interquartile range)), the sum of n-6 fatty acids (19.94 (19.06-20.53)%) and the sum of polyunsaturated fatty acids (22.70 (21.31-23.28)%) were higher in infants with atopic eczema compared with non-atopic eczema (12.69 (10.87-13.93); 17.72 (15.63-18.91) and 19.90 (17.64-21.06), respectively; P<0.05) and controls (12.50 (12.16-13.42); 18.19 (17.43-18.70) and 20.32 (19.32-21.03), respectively; P<0.05). Serum phospholipid gamma-linolenic acid was lower in both atopic and non-atopic eczema compared with controls (P<0.05) and additionally eicosapentaenoic acid was higher in atopic eczema compared with controls (P<0.05). These preliminary results suggest differences in fatty acid compositions between the two types of eczema, calling for further evaluation in a larger setting. The two types of eczema may be regulated by different immunological processes, and fatty acids may have a more profound role in the atopic type.

Liposomes modulate Kupffer cell endotoxin response.

To test the hypothesis that pretreatment with liposomes enriched with the omega 3 fatty acid docosahexaenoic acid (22:6 omega 3) will alter the Kupffer's cell and systemic cytokine (tumor necrosis factor and interleukin-6) response to endotoxin challenge, and to demonstrate alterations in Kupffer's cell phospholipid fatty acid composition after in vivo liposome treatment. Nonrandomized controlled laboratory investigation in Wistar rats. Animals were assigned to three pretreatment groups: no liposomes; liposomes, 100 mg/kg; or liposomes, 400 mg/kg given by bolus intravenous injection with the animals under inhalation anesthesia. Eighteen hours after liposome treatment, each group was challenged with Escherichia coli lipopolysaccharide (3 mg/kg intraperitoneally in 10 mL of lactated Ringer's solution) or lactated Ringer's solution only. In a separate set of experiments, Kupffer's cells were obtained from animals pretreated with liposome, 400 mg/kg, or controls and challenged with lipopolysaccharide (1, 100, or 10(4) ng/mL) in vitro. Serum and Kupffer's cell supernatant tumor necrosis factor and interleukin-6 bioactivity, Kupffer's cell phospholipid fatty acid composition, survival, and liver histologic findings. In vivo liposome pretreatment (400 mg/kg) resulted in significant increases in serum tumor necrosis factor and interleukin-6 levels 90 minutes after intraperitoneal lipopolysaccharide challenge (P < .05 vs no liposomes). Kupffer's cells isolated from liposome-treated animals (400 mg/kg) compared with untreated controls release significantly more tumor necrosis factor and interleukin-6 after lipopolysaccharide stimulation in vitro in a dose-dependent response (P < .05). Liposome treatment increased total polyunsaturated fatty acid, total omega 3, and docosahexaenoic acid 22:6 omega 3 content in Kupffer's cell phospholipids compared with untreated controls. Survival 24 hours after lipopolysaccharide challenge was reduced by liposome (400 mg/kg) pretreatment (P < .05 by chi 2 test). Livers from each treatment group demonstrated focal areas of hepatocyte necrosis and inflammatory cells. Liposome pretreatment increases the circulating and Kupffer's cell cytokine response to endotoxemia, increases Kupffer's cell polyunsaturated fatty acid content, and is associated with reduced survival.

Dietary Fat and Fiber Alter Rat Colonic Mucosal Lipid Mediators and Cell Proliferation

To better understand the biochemical mechanisms by which dietary fat and fiber modulate colonic cell proliferation, we determined the effect of dietary fats and fibers on rat colonic epithelial cell phospholipid mass and composition and on two metabolic products of phospholipids, prostaglandins and diacylglycerol (DAG). In a 3 x 3 factorial design, groups of 10 male Sprague-Dawley rats were fed one of nine experimental diets for 3 wk: three types of fat at 15 g/100 g (beef tallow, corn oil or fish oil) x two types of fiber (pectin or cellulose) or fiber-free as a control group. Dietary treatment did not alter phospholipid or DAG mass, although the fatty acid compositions of membrane phospholipids and DAG were altered by dietary treatment. Arachidonic acid [20:4(n-6)] and eicosapentaenoic acid [20:5(n-3)] in colonic mucosal phospholipid and DAG were associated with higher and lower indices of cell proliferation, respectively. These correlations were specific for the distal colon, which was the principle site of dietary fat effects on cell proliferation. Prostaglandin E and prostacyclin synthesis in colonic mucosa and muscle was significantly lower in fish oil-fed compared with beef tallow- and corn oil-fed animals (by 46-90%, P < 0.001), in both the proximal and distal colon. Correlations between prostaglandin production and cell proliferation, however, were significant only in the distal colon. These data raise the possibility that dietary fat and fiber may modulate intracellular events related to cell proliferation via their effects on epithelial cell phospholipid fatty acid composition, and subsequently on prostaglandin production and DAG composition.

Essential Fatty Acid Deficiency in Cultured Human Keratinocytes Attenuates Toxicity Due to Lipid Peroxidation

Human keratinocytes are commonly grown in culture with a serum-free medium. Under these conditions, keratinocytes become essential fatty acid deficient (EFAD), as determined by gas chromatographic analysis of cell phospholipid fatty acid composition. Exposure of EFAD keratinocytes for 2 hr to concentrations of t-butyl hydroperoxide (tBHP) up to 2 mM did not result in toxicity assessed by lactate dehydrogenase (LDH) release and only a small indication of lipid peroxidation assessed by the release of thiobarbituric acid-reactive substances (TBARS). Addition of 10 μM linoleic acid (LA) to serum-free medium alleviated the EFAD condition by increasing the phospholipid content of LA and its elongation and desaturation products, arachidonic acid and docosatetraenoic acid. Exposure of LA-supplemented keratinocytes to tBHP resulted in significant LDH (at 1 and 2 mM tBHP) and TBARS (tBHP concentration dependent) release. TBARS release was also significantly elevated in unexposed LA-supplemented keratinocytes (basal release). Cosupplementation with the antioxidant, α-tocopherol succinate (TS) prevented tBHP (1 mM)-induced LDH release in LA-supplemented cultures. TS supplementation also attenuated the effect of tBHP on TBARS release, but when compared to TS-supplemented EFAD cultures, LA supplementation still led to increased tBl-IP-induced TBARS release. Keratinocyte cultures are potentially useful as an alternative to animals in toxicology research and testing. It is important, however, that the cell model provide a response to toxic insult similar to that experienced in vivo. Our results suggest that fatty acid and antioxidant nutrition of cultured keratinocytes are important parameters in mediating the toxic effects of lipid peroxidation.