Essential fatty acids in cystic fibrosis

Glued in lipids: Lipointoxication in cystic fibrosis

Cystic Fibrosis (CF) is an autosomal recessive disease caused by mutations in the CF transmembrane regulator (CFTR) gene, which encodes a chloride channel located at the apical surface of epithelial cells. Unsaturated Fatty Acid (UFA) deficiency has been a persistent observation in tissues from patients with CF. However, the impacts of such deficiencies on the etiology of the disease have been the object of intense debates. The aim of the present review is first to highlight the general consensus on fatty acid dysregulations that emerges from, sometimes apparently contradictory, studies. In a second step, a unifying mechanism for the potential impacts of these fatty acid dysregulations in CF cells, based on alterations of membrane biophysical properties (known as lipointoxication), is proposed. Finally, the contribution of lipointoxication to the progression of the CF disease and how it could affect the efficacy of current treatments is also discussed.

The Efficacy of MAG-DHA for Correcting AA/DHA Imbalance of Cystic Fibrosis Patients

Omega-3 polyunsaturated fatty acid (n-3 PUFA) supplementations are thought to improve essential fatty acid deficiency (EFAD) as well as reduce inflammation in Cystic Fibrosis (CF), but their effectiveness in clinical studies remains unknown. The aim of the study was to determine how the medical food containing docosahexaenoic acid monoglyceride (MAG-DHA) influenced erythrocyte fatty acid profiles and the expression levels of inflammatory circulating mediators. We conducted a randomized, double blind, pilot trial including fifteen outpatients with Cystic Fibrosis, ages 18–48. The patients were divided into 2 groups and received MAG-DHA or a placebo (sunflower oil) for 60 days. Patients took 8 × 625 mg MAG-DHA softgels or 8 × 625 mg placebo softgels every day at bedtime for 60 days. Lipid analyses revealed that MAG-DHA increased docosahexaenoic acid (DHA) levels and decrease arachidonic acid (AA) ratio (AA/DHA) in erythrocytes of CF patients following 1 month of daily supplementation. Data also revealed a reduction in plasma human leukocyte elastase (pHLE) complexes and interleukin-6 (IL-6) expression levels in blood samples of MAG-DHA supplemented CF patients. This pilot study indicates that MAG-DHA supplementation corrects erythrocyte AA/DHA imbalance and may exert anti-inflammatory properties through the reduction of pHLE complexes and IL6 in blood samples of CF patients. Trial registration: Pro-resolving Effect of MAG-DHA in Cystic Fibrosis (PREMDIC), NCT02518672.

Abnormal unsaturated fatty acid metabolism in cystic fibrosis: biochemical mechanisms and clinical implications

Cystic fibrosis is an inherited multi-organ disorder caused by mutations in the CFTR gene. Patients with this disease exhibit characteristic abnormalities in the levels of unsaturated fatty acids in blood and tissue. Recent studies have uncovered an underlying biochemical mechanism for some of these changes, namely increased expression and activity of fatty acid desaturases. Among other effects, this drives metabolism of linoeate to arachidonate. Increased desaturase expression appears to be linked to cystic fibrosis mutations via stimulation of the AMP-activated protein kinase in the absence of functional CFTR protein. There is evidence that these abnormalities may contribute to disease pathophysiology by increasing production of eicosanoids, such as prostaglandins and leukotrienes, of which arachidonate is a key substrate. Understanding these underlying mechanisms provides key insights that could potentially impact the diagnosis, clinical monitoring, nutrition, and therapy of patients suffering from this deadly disease.

The prevalence of fat-soluble vitamin deficiencies and a decreased bone mass in patients with chronic pancreatitis

BACKGROUND/OBJECTIVES

In chronic pancreatitis, malabsorption of fat is common due to loss of exocrine function. Consequently, these patients are at risk to acquire deficiencies of the fat-soluble vitamins, which may result in a decreased bone mineral density (BMD) and the development of osteopenia and osteoporosis.

METHODS

We prospectively enrolled all patients diagnosed with chronic pancreatitis, who visited our outpatient clinic between March and November 2011. Data were collected regarding demographic characteristics, symptoms, and pancreatic function. Serum concentrations of vitamins A, E, K, and D were determined, and BMD was assessed by means of bone densitometry. Results were analyzed according to pancreatic function status and enzyme use, and compared to reference data, when available.

RESULTS

Forty patients were included (43% female; mean age of 52). Alcohol abuse was the major cause of pancreatitis (50%). Twenty-eight patients were exocrine insufficient (70%), of whom 19 used pancreatic enzymes. Vitamin A, D, E, and K deficiencies were present in 3, 53, 10, and 63% of patients, respectively. Osteopenia and osteoporosis were observed in 45% and 10% of patients. A decreased BMD was more frequently observed than expected, based on reference data, even in exocrine sufficient patients.

CONCLUSIONS

Deficiencies of fat-soluble vitamins and a decreased BMD are frequently present in chronic pancreatitis, even in exocrine sufficient patients. Consequently, all patients with chronic pancreatitis should be routinely screened for fat-soluble vitamin deficiencies and a decreased BMD.

The daily practice of pancreatic enzyme replacement therapy after pancreatic surgery: a northern European survey: enzyme replacement after surgery

INTRODUCTION

After pancreatic surgery, up to 80 % of patients will develop exocrine insufficiency. For enzyme supplementation to be effective, prescribing an adequate dose of pancreatic enzymes is mandatory but challenging because the required dose varies. Data on the practice of enzyme replacement therapy after surgery are lacking, and therefore, we conducted this analysis.

METHODS

An anonymous survey was distributed to members of the Dutch and German patient associations for pancreatic disorders. The target population consisted of patients with chronic pancreatitis or pancreatic cancer who had undergone pancreatic surgery and were using enzymes to treat exocrine insufficiency. Results were compared to a similar group of non-operated patients.

RESULTS

Ninety-one cases were analyzed (84 % underwent a resection procedure). The median daily enzyme dose was 6, and 25 % took three or less capsules. Despite treatment, 68 % of patients reported steatorrhea-related symptoms, 48 % adhered to a non-indicated dietary fat restriction, and only 33 % had visited a dietician. The outcome was equally poor for the 91 non-operated patients.

CONCLUSION

Most patients suffering from exocrine insufficiency after pancreatic surgery are undertreated. To improve efficacy, physicians should be more focused on treating exocrine insufficiency and educate patients to adjust the dose according to symptoms and their diet.

Patients with exocrine insufficiency due to chronic pancreatitis are undertreated: a Dutch national survey

BACKGROUND

Treating exocrine pancreatic insufficiency with pancreatic enzymes is challenging because there is no fixed dose regimen. The required dose varies per patient, depending on the residual pancreatic function, the gut lumen physiology, and the fat content of each meal. Using a sufficient dose of enzymes is crucial to prevent weight loss, nutritional deficiencies, and to ameliorate steatorrhea-related symptoms. Data regarding the practise of enzyme replacement therapy are lacking. Therefore, we evaluated if patients with exocrine insufficiency caused by chronic pancreatitis receive proper treatment in the Netherlands.

METHODS

An anonymous survey was distributed to the members of the Dutch Association of Patients with Pancreatic Disorders. The survey focused on enzyme use, steatorrhea-related symptoms, dietary consultation, and food restrictions. Responding patients were included if they had chronic pancreatitis and were treated for exocrine insufficiency with pancreatic enzymes.

RESULTS

The survey was returned by 178 members who suffered from chronic pancreatitis, 161 of whom (90%) met the inclusion criteria. The mean age was 56 years and 53% were male. The median enzyme intake was 6 capsules per day and 25% of patients took 3 or less capsules. Remarkably, 70% of patients still reported steatorrhea-related symptoms, despite treatment. Only 25% of cases were referred to a dietician and 58% kept a restriction of fat (either instructed by a dietician or self-imposed).

CONCLUSION

Many patients with exocrine insufficiency caused by chronic pancreatitis are under-treated in the Netherlands, a country with a well-organized healthcare system. To improve treatment efficacy, patients should be educated in adjusting the enzyme dosage according to steatorrhea-related symptoms and dietary fat intake. Moreover, patients should be referred to a well-trained, specialized dietician.

Pancreatic enzyme replacement therapy in chronic pancreatitis

Exocrine pancreatic insufficiency (EPI) is a serious condition which occurs in several diseases including chronic pancreatitis (CP), cystic fibrosis, pancreatic cancer, and as a result of pancreatic surgery. The lack or absence of pancreatic enzymes leads to an inadequate absorption of fat, proteins, and carbohydrates, causing steatorrhoea and creathorrhea which results in abdominal discomfort, weight loss, and nutritional deficiencies. To avoid malnutrition related morbidity and mortality, it is pivotal to commence pancreatic enzyme replacement therapy (PERT) as soon as EPI is diagnosed. Factors as early acidic inactivation of ingested enzymes, under dosage, and patient incompliance may prevent normalisation of nutrient absorption, in particular of fat digestion. This review focuses on the current status of how to diagnose and treat EPI.

Lipid metabolism in cystic fibrosis

PURPOSE OF REVIEW

Expression of defective cystic fibrosis transmembrane conductance regulator (CFTR), the cause for cystic fibrosis, affects fatty acid, cholesterol and sphingolipid metabolism. This review summarizes recent observations and evaluates current understanding of mechanisms.

RECENT FINDINGS

Recent observations implicate CFTR, in addition to known effects on fatty acid and cholesterol metabolism, in the regulation of sphingolipid metabolism and suggest that this pathway is relevant to inflammation and infection. A common mechanism on how CFTR affects such a wide spectrum of lipid classes is currently not known. One mechanism for low linoleic acid, amenable to inhibition by docosahexaenoic acid, is increased metabolism in the n-6 fatty acid pathway. Accumulation of free cholesterol in distinct perinuclear compartments, reversible by overexpression of rab9, suggests that cystic fibrosis and the lysosomal storage disease Niemann-Pick-C could share similar cell signaling defects, in addition to increased cAMP signaling and sterol-regulatory element binding protein (SREBP) expression that affect cholesterol metabolism. Novel is the recognition that CFTR modulates ceramide mass and uptake of sphingosine-1- phosphate. Experiments in different cystic fibrosis-mouse models, although not able to establish whether ceramide mass is increased or decreased, suggest that normalization of ceramide decreases infection and selected parameters of inflammation, of relevance to the complex phenotype that characterizes cystic fibrosis.

SUMMARY

Expression of defective CFTR has profound effects on fatty acid, cholesterol and sphingolipid metabolism, for which mechanisms are currently poorly understood. Recent studies in different cystic fibrosis models suggest a causal relationship between altered ceramide mass and increased inflammation and susceptibility to infection. Studies in cystic fibrosis knockout mouse models suggest that normalization of ceramide decreases infection and inflammation. Studies that evaluate the diagnostic and clinical relevance of sphingolipids in patients with cystic fibrosis are needed.

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.

Mechanisms of lipid malabsorption in Cystic Fibrosis: the impact of essential fatty acids deficiency

Transport mechanisms, whereby alimentary lipids are digested and packaged into small emulsion particles that enter intestinal cells to be translocated to the plasma in the form of chylomicrons, are impaired in cystic fibrosis. The purpose of this paper is to focus on defects that are related to intraluminal and intracellular events in this life-limiting genetic disorder. Specific evidence is presented to highlight the relationship between fat malabsorption and essential fatty acid deficiency commonly found in patients with cystic fibrosis that are often related to the genotype. Given the interdependency of pulmonary disease, pancreatic insufficiency and nutritional status, greater attention should be paid to the optimal correction of fat malabsorption and essential fatty acid deficiency in order to improve the quality of life and extend the life span of patients with cystic fibrosis.

High-performance liquid chromatography/electrospray ionization ion-trap tandem mass spectrometric analysis and quantification of phosphatidylcholine molecular species in the serum of cystic fibrosis subjects supplemented with docosahexaenoic acid

Since phosphatidylcholine (PC) is the most abundant phospholipid (PL) class in human serum, its concentration represents an important marker for the evaluation of lipid absorption and metabolism. High-performance liquid chromatography coupled on-line with electrospray ionization ion-trap tandem mass spectrometry (HPLC/ESI-MS/MS) was successfully applied to the quantitative analysis of PC molecular species from serum of cystic fibrosis (CF) subjects before and after supplementation with docosahexaenoic acid (DHA). Seven molecular species of PC (containing C16:0/C20:4, C16:0/C22:6, C18:0/C20:4, C18:0/C22:6, C16:0/C18:1, C16:0/C18:2 and C18:0/C18:2, respectively) were quantified using MS in the negative scan mode with 1,2-diundecanoyl-sn-glycero-phosphocholine as the internal standard. The molecular species containing DHA, C16:0/C22:6 and C18:0/C22:6, increased from 41.3 +/- 31.7 and 33.1 +/- 18.2 to 85.4 +/- 20.4 and 52.1 +/- 20.7 microg/mL serum, respectively, after a 3-month supplementation. Interestingly, the species containing arachidonic acid (C18:0/C20:4 and C16:0/C20:4) decreased from 115 +/- 55 and 139 +/- 57 to 58.1 +/- 22.5 and 70.5 +/- 28.1, respectively. HPLC/ESI-MS/MS allowed the direct analysis of the lipid extract without previous purification of PLs, thus it is a useful analytical support in CF research in order to understand the extent of lipid dysfunctions typical of CF or other diseases. The present method might also be used for quantitative analysis of each serum phospholipid class molecular species. However, the instrument response was found to be very dependent on the phospholipid class considered, and thus the use of appropriate standards for each class of PLs is recommended.

Molecular species compositions of lung and pancreas phospholipids in the cftr(tm1HGU/tm1HGU) cystic fibrosis mouse

Fatty acid analysis of phospholipid compositions of lung and pancreas cells from a cystic fibrosis transmembrane regulator (CFTR) negative mouse (cftr(-/-))suggested that a decreased concentration of docosahexaenoate (22:6(n-3)) and increased arachidonate (20:4(n-6)) may be related to the disease process in cystic fibrosis (CF). Consequently, we have determined compositions of the major phospholipids of lung, pancreas, liver, and plasma from a different mouse model of CF, the cftr(tm1HGU/tm1HGU) mouse, compared with ZTM:MF-1 control mice. Electrospray ionization mass spectrometry permitted the quantification of all of the individual molecular species of phosphatidylcholine (PtdCho), phosphatidylethanolamine (PtdEtn), phosphatidylglycerol (PtdGly), phosphatidylserine (PtdSer), and phosphatidylinositol (PtdIns). There was no deficiency of 22:6(n-3) in any phospholipid class from lung, pancreas, or liver from mice with the cftr(tm1HGU/tm1HGU). Instead, the concentration of 20:4(n-6) was significantly decreased in plasma PtdCho species and in pancreas and lung species of PtdEtn, PtdSer, and PtdIns. These results demonstrate the variability of membrane phospholipid compositions in different mouse models of CF and suggest that in cftr(tm1HGU/tm1HGU) mice, the apparent deficiency was of 20:4n-6- rather than of 22:6n-3-containing phospholipid species. They highlight a need for detailed phospholipid molecular species analysis of cells expressing mutant CFTR from children with CF before the therapeutic effects of administering high doses of 22:6(n-3)-containing oils to children with CF can be fully evaluated.

Adenovirus-mediated human pancreatic lipase gene transfer to rat bile: gene therapy of fat malabsorption

This study explored the potential of using the gene therapy approach, based on adenovirus-mediated expression of pancreatic lipase in the hepatobiliary tract, to increase lipid digestion in the intestinal lumen and promote lipid absorption through the gastrointestinal tract. Recombinant adenovirus containing the human pancreatic lipase cDNA (AdPL) was shown to transduce and mediate pancreatic lipase biosynthesis in rat IEC-6 epithelial cells in vitro. Retrograde infusion of recombinant adenovirus (3 x 10(8) plaque-forming units) containing the bacterial LacZ gene (AdLacZ) into the bile duct of rats resulted in positive X-gal reaction products in the periportal liver cells 7 days after AdLacZ infusion. A high level of human pancreatic lipase was detected in bile after retrograde bile duct infusion of rats with AdPL but not in the bile of animals infused with AdLacZ. Triglyceride hydrolytic activity in the bile of AdPL-infused rats was equivalent to that present in pancreatic juice. In contrast, serum obtained from these animals did not contain any detectable pancreatic lipase activity. These results suggest that ectopic expression of pancreatic enzymes in the hepatobiliary tract may be an alternative therapeutic strategy for treating fat malabsorption due to pancreatic insufficiency.

Malnutrition-associated rash of cystic fibrosis

Rash is a rare presenting sign of cystic fibrosis (CF) complicated by protein-calorie malnutrition. We measured essential fatty acid (EFA) levels in the serum of a 4-month-old girl with an erythematous, desquamating, periorificially accentuated rash in association with malnutrition and her 2-year-old sister who was diagnosed concurrently with CF but had no rash or signs of malnutrition. Both patients had biochemical evidence of EFA deficiency, suggesting that development of the rash is multifactorial. Clinical presentation, management, and possible modes of pathogenesis of the rash are reviewed. Pathogenesis of the rash appears to involve a complex interaction among deficiencies of EFAs, zinc, protein, and possibly copper, leading to disordered prostaglandin metabolism or cytokine production, or free radical-induced damage to cellular membranes due to a lack of nutrient-derived protective antioxidants.

Fatty acid composition of lipoprotein lipids in hepatobiliary diseases

Liver damage and alterations in the exocrine function of the gland lead to a profound alteration of the plasma lipoprotein profile. To determine whether hepatic disease results in changes in the lipoprotein fatty acid composition, i.e. to determine whether liver function influences the homeostasis of complex lipids in plasma, we studied the fatty acid profile of lipids from VLDL, LDL and HDL, as well as from total plasma, in thirty-one patients of both sexes with hepatobiliary pathology (compensated liver cirrhosis, uncompensated liver cirrhosis, primary biliary cirrhosis, other intrahepatic cholestasis, and acute viral hepatitis). We also studied a group of healthy adults as controls. We present the lipoprotein profile and the fatty acid composition (myristic C14, palmitic C16, palmitoleic C16: 1, stearic C18, oleic C18: 1, linoleic C18: 2, eicosatrienoic C20: 3 omega 6 and arachidonic C20: 4) of lipoprotein and total plasma triacylglycerols, cholesteryl esters and phospholipids. The main observation of this study is that, despite the profound changes in the lipoprotein profile and the lower abundance of polyunsaturated fatty acids in complex lipids, the composition of all triacylglycerols, cholesteryl esters and phospholipids is very similar for the corresponding lipoproteins of patients with hepatobiliary disease and of control subjects. This indicates that in the controls as in the studied patients, the exchange of lipids between plasmatic lipoproteins is very rapid and demonstrates the possible importance of the extrahepatic synthesis of cholesteryl ester transfer protein.

The use of an intravenous fish oil emulsion enriched with omega-3 fatty acids in patients with cystic fibrosis

The effects of parenteral nutrition supplemented with a lipid emulsion enriched with the omega-3 fatty acids (FA), eicosapentaenoate (20:5n-3) and docosahexaenoate (22:6n-3), derived from fish oil were compared to a standard lipid emulsion containing omega-6 FA in patients with cystic fibrosis (CF). Patients were randomized to receive either Omegavenous 10%, which contains fish oil (IFO), or Liposyn III 10% (control) daily for 1 mo at a dose of 150 mg/kg. There were no observed allergic or toxic reactions, no abnormalities in liver function tests or coagulation parameters. To assess the bioavailability of the lipid administered, measurement of plasma free fatty acid (FFA) levels were made of the essential FA. There were no adverse changes in plasma levels of the omega-6 FA (18:2n-6, 18:3n-6, 20:3n-6, and 20:4n-6), and plasma levels of the omega-3 FA (20:5n-3 and 22:6n-3) increased significantly during the 1-mo study. There were no significant changes in plasma FFA profiles of the essential FA for the patients receiving the control lipid. The effect of treatment on pulmonary function was also investigated. There were no significant changes in FVC, FEV1, PEFR, FEV1/ FVC, or FEF25-75 (absolute value or percentage) over the 4 weeks of study in the group receiving IFO or control. This preliminary investigation suggests that intravenous administration of fish oils enriched with long chain omega-3 FA to patients with CF is safe and bioavailable.

Impaired resistance to oxidation of low density lipoprotein in cystic fibrosis: improvement during vitamin E supplementation

Antioxidants such as vitamin E protect unsaturated fatty acids of LDL against oxidation. In the ex vivo model used, LDL was exposed to Cu2+ ions, a potent prooxidant capable of initiating the oxidation of LDL. The lag time, indicating the delay of conjugated diene formation in LDL due to antioxidant protection, was measured in 54 cystic fibrosis (CF) patients with plasma alpha-tocopherol levels below (Group A, n = 30) or above (Group B, n = 24) 15.9 mumol/L (mean - 2 SD of Swiss population). Patients were reevaluated after 2 months on 400 IU/d of oral RRR-alpha-tocopherol. In group A, alpha-tocopherol concentrations in LDL increased significantly from 3.2 +/- 1.6 mol/mol LDL to 8.2 +/- 2.8 mol/mol (P < 0.001) and lag times increased from 79 +/- 33 min to 126 +/- 48 min (P < 0.001), whereas in the vitamin E sufficient group B no further increase neither in LDL alpha-tocopherol concentrations or in lag times was observed. LDL oleic acid concentrations were higher, and linoleic acid concentrations were lower in patients than in controls. After efficient vitamin E supplementation, lag times were positively related to LDL alpha-tocopherol (P < 0.01) and negatively to LDL linoleic and arachidonic acid content (P < 0.001). The maximum rate of oxidation correlated positively with linoleic and arachidonic acid concentrations, as did the maximum conjugated diene absorbance. These results indicate that LDL resistance to oxidation is impaired in vitamin E deficient CF patients but can be normalized within 2 months when alpha-tocopherol is given in sufficient amounts. Linoleic and arachidonic acid content exhibit a major influence on the LDL resistance to oxidation.

Plasma lipid concentrations in children with cystic fibrosis: the value of a high-fat diet and pancreatic supplementation

Impaired digestion of dietary fat is an almost universal feature of cystic fibrosis (CF) which results in low concentrations of essential fatty acids in plasma lipids. We have evaluated the effect of a high-lipid diet and pancreatic enzyme supplementation, using enteric-coated microsphere preparations, on plasma lipid concentrations in paediatric CF patients. Absorption of dietary lipid was comparable between control and CF subjects. This resulted in plasma cholesterol, triacylglycerol, total phosphatidylcholine and individual phosphatidylcholine molecular species concentrations in CF patients which were in the same range as those in controls. Normal values for these variables were also found in patients with clinically detectable liver disease. These results show that present dietary management of CF patients supports normal plasma lipid concentrations.

Human milk in disease: lipid composition

Differences in the lipid composition of human milk have been described in maternal diseases known to affect fat metabolism. Diseases such as diabetes, cystic fibrosis, hypobetalipoproteinemia and Type I hyperlipoproteinemia affect the quantity and quality of human milk fat. Increased fatty acid chain elongation and changes in desaturation (especially delta 6 desaturase), as well as changes in lipid class composition, have been shown in diabetes and cystic fibrosis, whereas compensatory increases in medium-chain fatty acids have been described in hypobetalipoproteinemia and Type I hyperlipoproteinemia. It is important to realize that these observations were made either on single women or on very small groups of women. In infant diseases, such as breast milk jaundice and ectopic eczema, changes in polyunsaturated fatty acids in maternal milk have been described.

Lipid metabolism in bile acid malabsorption

Malabsorption of bile acid increases cholesterol synthesis and activates hepatic LDL receptors which leads to enhanced elimination of cholesterol from the body. Interruption of enterohepatic circulation of bile acids may lead to a smaller bile acid pool, which, in turn, impairs cholesterol and fat absorption by reduced micellar solubilization. Together with reduced cholesterol absorption, the increased cholesterol loss as bile acids also reduces plasma cholesterol concentrations and the biliary cholesterol excretion, too. Diminished biliary cholesterol in bile acid malabsorption may contribute to the increased incidence of gallstones associated with ileal dysfunction. Malabsorption of bile acid leads to a fall in LDL-cholesterol concentration, and an increase of HDL-cholesterol concentration has been reported. VLDL-triglyceride concentrations are almost invariably raised. Enhanced cholesterol and bile acid synthesis in ileal dysfunction is reflected by raised concentrations of plasma cholesterol precursors, especially lathosterols, which can be used as an indicator of increased bile acid loss to faeces. Cholesterol absorption, in turn, correlates positively with plasma plant sterol concentrations levels and the ratio of lathosterols to campesterols can be used as a screening measurement for ileal dysfunction. Plasma fatty acid composition is also altered as a response to fat malabsorption associated with ileal dysfunction. The proportion of essential fatty acids is inversely correlated with faecal fat excretion and endogenous fatty acid synthesis is activated.

Two cases of cystic fibrosis in Japanese children: studies on the essential fatty acid and prostaglandin metabolism

We describe the fatty acid (FA) and prostaglandin (PG) metabolism in two Japanese cases of cystic fibrosis (CF) with or without pancreatic insufficiency (PI). The diagnosis of CF was based on the elevated sweat chloride concentration by pilocarpine iontophoresis. A 1-month-old boy (case 1) showed poor weight gain, steatorrhea and scaly dermatitis, but no respiratory symptoms were noted. He had decreased levels of serum linoleate and arachidonate, and increased palmitoleate and oleate levels, indicating essential fatty acid (EFA) deficiency. Supplementation of fat-emulsion improved his skin lesions and the altered FA pattern within a few months, associated with the definite reduction of the urinary PG F2 alpha levels. Until two years of age, he has been free from respiratory symptoms. A 12-year-old girl (case 2) had had recurrent respiratory tract infections due to Pseudomonas aeruginosa and Staphylococcus aureus for several years, and her pancreatic functions were preserved. The FA patterns of her serum lipid were almost within the normal range. These results indicate that 1) the altered FA composition appeared to be a secondary consequence of PI commonly complicating CF and 2) the correction of the altered FA and PG metabolism might have a beneficial effect on the respiratory function of CF patients with EFA deficiency.

Relationships between essential fatty acid levels, pulmonary function and fat absorption in pre-adolescent cystic fibrosis children with good clinical scores

Twenty-one pre-adolescent cystic fibrosis (CF) children with good clinical scores had significant (P less than 0.001) deficiencies of arachidonic (mean 3.8% of total plasma fatty acids +/- SD 1.4) and linoleic (18.1 +/- 6.3) acids compared with controls (6.0 +/- 1.0, and 27.6 +/- 3.9, respectively). Despite the presence of pulmonary involvement of varying severity in all the CF children, neither arachidonic nor linoleic acid levels correlated significantly with pulmonary function measured by spirometry. All children had adequate caloric and fat intakes, and the coefficient of fat absorption correlated with none of the deficient fatty acid levels. These findings suggest that deficiencies of arachidonic and linoleic acids are of minor importance in the early development of pulmonary involvement in CF, and that factors other than fat malabsorption and decreased dietary intake probably contribute to fatty acid deficiency.

The partial ileal bypass operation does not cause essential fatty acid deficiency

Recent studies have indicated that ileal resection may lead to essential fatty acid deficiency, as demonstrated by plasma fatty acid composition. In the present study the serum cholesterol ester fatty acid composition was determined in patients who had undergone a partial ileal bypass operation several years earlier. The mean length of ileal exclusion was 2.0 m (range, 1.4-2.5 m). The patients with ileal bypass had severe bile acid malabsorption and slight fat malabsorption (fecal fat, 16 g/day). The fatty acid composition of serum cholesterol esters in the patients with ileal exclusion was identical with that of matched controls; for example, linoleic acid comprised 58% of the C14-18 fatty acids in the control patients and 61% in the patients with ileal bypass. It is concluded that exclusion of the distal third of a healthy small bowel does not cause essential fatty acid deficiency.

Status of plasma and erythrocyte fatty acids and vitamin A and E in young children with cystic fibrosis

The fatty acid (FA) status in young children with cystic fibrosis (CF) was investigated. The FA composition of the plasma cholesterol esters (CE) and phospholipids (PL) and of the erythrocyte phosphatidylcholine (PC) and phosphatidylethanolamine (PE) was estimated in 11 patients with CF and pancreatic insufficiency (median age, 3.0 years; range, 3 months to 7 years) and in 10 age-matched controls. Linoleic acid values ranged widely but were not significantly reduced in the patients. However, arachidonic acid (20:4w6) and docosahexaenoic acid were decreased in all lipid classes. The ratio of dihomo-gamma-linoleic acid to arachidonic acid (20:3w6/20:4w6) was significantly increased in the patients, indicating an impairment of FA metabolism (delta 5-desaturation). Plasma retinol concentrations were normal and did not differ between the supplemented patients and controls. Plasma total tocopherols and alpha-tocopherol and their ratios to total lipids were significantly reduced in the CF patients, but all values were within the normal ranges for the pediatric age group, and no child met the criterion for vitamin E deficiency.

Control of polyunsaturated acids in tissue lipids

Since the discovery in 1929 that certain polyunsaturated fatty acids (PUFA) are essential for life and health, intense investigation has revealed the multiplicity of members in each of several families of PUFA, no two of which are equivalent. The quantified nutrient requirements for the essential dietary precursors of the two dominant families of PUFA have been estimated, and the general functions of these families are slowly becoming known. The PUFA are essential components of structural membrane lipids. The functions of the individual members are not yet differentiated, except as they act as precursors of synthesis of unique octadecanoid, eicosanoid, and docosanoid products of oxidation that have potent biological properties. The PUFA occur in animals and higher plants as ubiquitous and essential components of structural lipid that are in a dynamic equilibrium with the pool of dietary acyl groups. Many human diseases have been found to involve unique essential fatty acid (EFA) deficiencies or distortions of the normal equilibrium pattern. The equilibrium is influenced by the level of dietary intake or precursors, by the presence of competing essential and nonessential acyl groups, by nonoptimum intake of other essential nutrients, by hormonal effects, by drug therapy, and by other effects upon physiological condition. With the many variables already known to modulate or control the equilibrium, it should be possible with more precise understanding of each variable to shift abnormal equilibria in the direction of normalcy. This perhaps will be the next area of intensive investigation in this field of nutrition and metabolism.

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.

Abnormal fatty acid pattern of the plasma cholesterol ester fraction in cystic fibrosis patients with and without pancreatic insufficiency

In our previous work it was found that in cystic fibrosis patients with and without pancreatic insufficiency, the fatty acid pattern of the plasma long chain, non-esterified fatty acid fraction is strikingly abnormal in comparison with the corresponding pattern of healthy subjects. However, other investigators have shown abnormal fatty acid patterns only in patients with pancreatic insufficiency. Therefore, we studied the plasma cholesterol ester fraction in cystic fibrosis patients of both types by gas liquid chromatography. It was found that the absolute total concentration of the plasma cholesterol esters in cystic fibrosis patients with and also without pancreatic insufficiency is significantly lower than in healthy subjects. Furthermore, the fatty acid pattern of this lipid fraction is significantly abnormal in both groups of patients, although to a lesser extent in patients without pancreatic insufficiency.

The role of nutritional status, airway obstruction, hypoxia, and abnormalities in serum lipid composition in limiting exercise tolerance in children with cystic fibrosis

Previous work has shown that impaired exercise tolerance in children with cystic fibrosis (C.F.) is related to the severity of airway obstruction without elucidating the possible roles of hypoxia or malnutrition. It has been suggested that poor nutrition leads to abnormalities in serum fatty acids composition, which may lead to tissue hypoxia. We investigated the roles of hypoxia, pulmonary mechanics, nutritional status, and serum fatty acid composition in limiting exercise tolerance in C.F. In 20 children with C.F., exercise tolerance, while breathing air and while breathing oxygen, was evaluated on a cycle ergometer and compared to pulmonary function tests, anthropometric data, serum lipid compostition, and clinical condition. The mean percent work expected from height (Wmax) was 75, and was unchanged by O2. Wmax correlated significantly with the degree of respiratory impairement, the discrepancy between height and weight, and the clinical score but not serum fatty acid composition. Where measured, no child at any time had an elevated end tidal CO2(PetCO2). We conclude that nutritional status and airway obstruction are closely correlated with exercise tolerance in C.F. and that, unlike the case in adults with chronic obstructive pulmonary disease, exercise-limiting dyspnea occurs in the presence of a normal PetCO2.

Excretion of bile acids in healthy children and children with cystic fibrosis

Urinary bile acid excretion was investigated in twenty-two patients with cystic fibrosis (CF) and in seven healthy children. CF patients with and without antibiotic treatment were compared. Bile acids were determined in 24-h samples after separation into unconjugated, glycine conjugated, taurine conjugated and sulphate conjugated bile acids. In total twenty bile acids were identified of which cholic, chenodeoxycholic, 3 beta-hydroxy-5-cholenoic acid and 24-nor-5 beta-cholan-23-oic acid were routinely present in samples collected from both CF patients and healthy children. None of the other bile acids were preferentially excreted by CF patients. When compared with the normal group, no statistical significance could be attached to the increased total urinary bile acids excreted by the CF patients (due to the large individual variations). The CF patients excreted increased amounts of cholic acid, 3 alpha, 7 beta, 12 alpha-and 3 beta, 7 beta, 12 alpha-trihydroxy-5 beta-cholanoic acids mainly in the unconjugated state. After administration of 24-[14C]cholic acid to thirteen CF patients the isotope excretion in faeces and urine was studied. Most of the patients had a high faecal excretion indicating great losses of bile acids from enterohepatic circulation. Compared to normal adults CF children excreted isotope in increased amounts in the urine.

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.

[Fatty acid patterns and glucose tolerance in Huntington's chorea (author's transl)]

Fatty acid patterns of plasma lipids and glucose-tolerance in Huntington's chorea. 25 patients with Huntington's chorea of various manifestation (9 predisposed symptomefree, 5 with light and 11 with severe manifestation) had studies of carbohydrate and lipid metabolism. These studies measured glucose-tolerance tests, insulin-, HGH-secretion, serum lipids and plasma fatty acid conposition of the cholesterylesters, triglycerides and phospholipids. The reactive insulin- but not HGH-levels were significantly raised, 32 % of the patients with Huntington's chorea had abnormal glucose-tolerance tests, compared with 3.2 % in a control group. Duration of symptoms correlated with higher cholesterol levels. Minor deviations were found in the fatty acid patterns in various lipid clases.

Concurrent determination of alpha-tocopherol and free fatty acids in human plasma by glass open tubular capillary column gas chromatography

A new gas chromatographic procedure was developed for the concurrent analysis of mixtures of long-chain acids (as methyl esters), cholesterol (as the trimethylsilyl ether) and the tocopherols (as trimethylsilyl ethers). This method was used in a study of free fatty acids and alpha-tocopherol in the plasma of normal subjects and stroke patients. The chromatographic separation was based upon the use of thermostable glass open tubular capillary columns prepared with Silanox (procedure of Lin, Pfaffenberger and Horning) and a new polar liquid phase (Schwartz-Mathews polyphenyl ether sulfone phase). The German-Horning injection system was used in a modified gas chromatograph.

Analysis of long-chain acids or human plasma phosphatidylcholines (lecithins) and cholesteryl esters by glass open tubular capillary column gas chromatography for stroke patients and for normal subjects

Methods are described for long-chain acid compositional analyses of human plasma phosphatidylcholines and plasma cholesteryl esters. Conventional procedures were employed for the isolation of these lipids and for the preparation of methyl esters of the acids. The gas chromatographic analytical procedure was based upon the use of thermostable glass open tubular capillary columns with a new polar phase. The methods were used in a study of plasma lipids in stroke patients and in normal young adult subjects.

Defective essential-fatty-acid metabolism in cystic fibrosis

Cystic fibrosis (C.F.) is characterised by low serum levels of essential fatty acids (E.F.A.). However, the fatty-acid pattern does not totally resemble that of dietary E.F.A. deficiency. The differences suggest a reduction in the desaturation of E.F.S. It is not known whether this defect is the primary lesion in C.F. or is the result of tissue damage in the disease. It is proposed that C.F. patients might have increased linoleic-acid requirements, and possibly specific requirements for its desaturation products.