Letter: Essential fatty acids and cystic fibrosis

An overview of monitoring and supplementation of omega 3 fatty acids in cystic fibrosis

Essential fatty acid deficiency has been increasingly reported in patients with cystic fibrosis. The purpose of this work is to critically summarize previous data on fatty acid status and omega3 supplementation in cystic fibrosis. Although the reported abnormalities differ from study to study, the two most consistent features appeared to be reduced circulating levels of linoleic acid and docosahexaenoic acid (DHA). On the assumption that the fatty acid composition of erythrocyte cell membranes may be similar to that of other organs, it seems appropriate to monitor the phospholipid profile from erythrocyte membranes together with circulating blood levels. Formulations containing widely variable DHA doses, ranging from 300 mg to 5 g per day, have been administered to patients with cystic fibrosis with discrepant outcomes. Randomized controlled trials are needed in order to draw firm conclusions on the therapeutic effect of omega3 fatty acid supplementation in cystic fibrosis.

Inflammatory pleuropulmonary fibrosis in essential fatty acid deficient rats and the lack of response to methysergide

In view of the association between essential fatty acid (EFA) deficiency and human cystic fibrosis, we have investigated the possible occurrence of pulmonary disease in rats fed an EFA deficient (EFAD) diet for 40 weeks. In contrast to a few slight spontaneous lesions consisting of pleural membrane hyperplasia, which were found in the lungs of control rats, a much greater incidence of fibrotic lesions was observed in the lungs of EFAD rats. These pleuropulmonary fibroses extended from the hyperplastic pleural membrane into the alveoli and were characterized by collagen deposition and marked macrophage infiltration to the extent that, in some cases, the alveolar septa were completely obstructed by inflammatory exudate. These findings lend indirect support to the contention that EFA deficiency plays a role in the aetiology of cystic fibrosis, at least with regard to pulmonary lesions. Administration of methysergide (10 mg/kg/day, p.o.) for a total of 11 weeks, did not alter the incidence of fibrosis in the lungs of EFAD rats, despite the finding that a man who had developed pleuropulmonary fibrosis as a result of chronic methysergide treatment exhibited a relative serum EFA deficiency. While a relative EFA deficiency may be a predisposing factor for the induction of fibrosis by chronic methysergide treatment, our data are not sufficient to make a decision upon this hypothesis.

Altered phospholipid composition and changed fatty acid pattern of the various phospholipid fractions of red cell membranes of cystic fibrosis children with pancreatic insufficiency

After two-dimensional thin-layer chromatography, it appears that the phospholipid composition of the erythrocyte membranes of cystic fibrosis children, compared with healthy ones, is changed by an increase of the phosphatidyl inositol content. The plasmalogen concentration of the membrane phospholipids is the same for both groups. The fatty acid pattern of the various red cell membrane phospholipid fractions was determined by gas chromatography (Tables II, III and IV), and significant changes were observed in the cystic fibrosis patients (Table V). Phosphatidyl choline and ethanolamine (non-plasmalogen forms) especially show strikingly abnormal fatty acid patterns similar to those in the various plasma lipid fractions.

Fatty acid composition of erythrocyte phospholipids from patients with cystic fibrosis

The phospholipid fatty acid composition of erythrocytes from patients with cystic fibrosis with pancreatic insufficiency, patients with cystic fibrosis with normal pancreatic enzyme function, and normal subjects was determined. Increased percentages of palmitoleic acid and total eicosatrienoic acid and a decreased percentage of linoleic acid were observed only in the cystic fibrosis patients with pancreatic insufficiency.

Plasma membrane lipids of human diploid fibroblasts from normal individuals and patients with cystic fibrosis

The lipid composition of isolated plasma membranes of human skin fibroblasts is described for the first time. Plasma membranes from a number of strains of fibroblasts from patients with cystic fibrosis and matched normals were isolated by a recently described procedure and analysed for major phospholipid classes, cholesterol and fatty acids. No differences in the quantities of these compounds were detected between cells of the two different origins. The fetal calf serum used to supplement the growth medium contained relatively more palmitoleate and oleate but less stearate than the membranes. There were also no consistent differences between cystic fibrosis and normal membranes in terms of the fatty acid compositions of their individual phospholipid classes. Consistent with this lack of chemical change in the lipids of membranes of cystic fibrosis cells, the degree of fluorescence polarization of diphenylhexatriene, an index of fluidity, was also unchanged.

Abnormal fatty-acid composition of plasma-lipids in cystic fibrosis. A primary or a secondary defect?

The percentage fatty-acid composition of the various plasma-lipid fractions from cystic-fibrosis patients with and without pancreatic insufficiency, obligate heterozygotes, and normal subjects was determined. Only the cystic-fibrosis patients with pancreatic insufficiency had significantly abnormal fatty-acid composition. This general observation did not correlate with vitamin-E deficiency, age, sex, or severity of the disease. Thus the altered fatty-acid composition of the different plasma-lipid fractions appears to be a secondary consequence of the pancreatic insufficiency commonly associated with cystic fibrosis and not a direct metabolic defect related to the cystic-fibrosis gene itself.