Determinants of Serum Glycerophospholipid Fatty Acids in Cystic Fibrosis

Role of Omega-3 fatty acids eicosapentaenoic (EPA) and docosahexaenoic (DHA) as modulatory and anti-inflammatory agents in noncommunicable diet-related diseases - Reports from the last 10 years

BACKGROUND & AIMS

Fatty acids are a fundamental component of the human diet, particularly polyunsaturated fatty acids, eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA). The importance of omega-3 fatty acids has been studied in the context of many diseases due to their pleiotropic effects, focusing on the anti-inflammatory effects of EPA and DHA. Currently, the results of these acids in noncommunicable diseases are being increasingly assessed in a broader context than just inflammation. However, the mechanisms underlying the modulatory and anti-inflammatory effects of omega-3 fatty acids remain the subject of intensive research. Therefore, we reviewed the literature covering articles from the last decade to assess not only the anti-inflammatory but, above all, the modulatory effect of EPA and DHA acids on noncommunicable diet-related diseases.

METHODS

The PubMed, Web of Science and Scopus databases were searched for studies regarding the effects of omega-3 fatty acids on diet-related disorders from the last 10 years.

RESULTS

The available research shows that EPA and DHA supplementation has a beneficial impact on regulating triglycerides, total cholesterol, insulin resistance, blood pressure, liver enzymes, inflammatory markers and oxidative stress. Additionally, there is evidence of their potential benefits in terms of mitochondrial function, regulation of plasma lipoproteins, and reduction of the risk of sudden cardiovascular events associated with atherosclerotic plaque rupture.

CONCLUSIONS

Omega-3 polyunsaturated fatty acids (EPA, DHA) have many beneficial effects among patients with diet-related disorders. More well-designed randomised controlled trials are needed to fully determine the usefulness of EPA and DHA in treating and preventing noncommunicable diet-related diseases.

Cross-talk between CFTR and sphingolipids in cystic fibrosis

Cystic fibrosis (CF) is the most common inherited, life-limiting disorder in Caucasian populations. It is caused by mutations in the gene encoding the cystic fibrosis transmembrane conductance regulator (CFTR), which lead to an impairment of protein expression and/or function. CFTR is a chloride/bicarbonate channel expressed at the apical surface of epithelial cells of different organs. Nowadays, more than 2100 CFTR genetic variants have been described, but not all of them cause CF. However, around 80-85% of the patients worldwide are characterized by the presence, at least in one allele, of the mutation F508del. CFTR mutations cause aberrant hydration and secretion of mucus in hollow organs. In the lungs, this condition favors bacterial colonization, allowing the development of chronic infections that lead to the onset of the CF lung disease, which is the main cause of death in patients. In recent years, evidence has reported that CFTR loss of function is responsible for alterations in a particular class of bioactive lipids, called sphingolipids (SL). SL are ubiquitously present in eukaryotic cells and are mainly asymmetrically located within the external leaflet of the plasma membrane, where they organize specific platforms capable of segregating a selected number of proteins. CFTR is associated with these platforms that are fundamental for its functioning. Considering the importance of SL in CFTR homeostasis, we attempt here to provide a critical overview of the literature to determine the role of these lipids in channel stability and activity, and whether their modulation in CF could be a target for new therapeutic approaches.

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.

Essential Fatty Acid Deficiency in Cystic Fibrosis Disease Progression: Role of Genotype and Sex

Adequate intake of nutrients such as essential fatty acids (EFA) are critical in cystic fibrosis (CF). The clinical course of deterioration of lung function in people with CF has been shown to relate to nutrition. Independent of the higher energy consumption and malabsorption due to pancreatic insufficiency, EFA deficiency is closely associated with the risk of pulmonary infection, the most significant pathology in CF. This review will focus on the EFA deficiency identified in people with CF, as well as the limited progress made in deciphering the exact metabolic pathways that are dysfunctional in CF. Specifically, people with CF are deficient in linoleic acid, an omega 6 fatty acid, and the ratio of arachidonic acid (omega 6 metabolite) and docosahexaenoic acid (omega 3 metabolite) is increased. Analysis of the molecular pathways in bronchial cells has identified changes in the enzymes that metabolise EFA. However, fatty acid metabolism primarily occurs in the liver, with EFA metabolism in CF liver not yet investigated, indicating that further research is required. Despite limited understanding in this area, it is well known that adequate EFA concentrations are critical to normal membrane structure and function, and thus are important to consider in disease processes. Novel insights into the relationship between CF genotype and EFA phenotype will be discussed, in addition to sex differences in EFA concentrations in people with CF. Collectively, investigating the specific effects of genotype and sex on fatty acid metabolism may provide support for the management of people with CF via personalised genotype- and sex-specific nutritional therapies.

Preclinical atherosclerosis in cystic fibrosis: Two distinct presentations are related to pancreatic status

BACKGROUND

Patients with cystic fibrosis (CF) are exposed to overlapping cardiovascular risk factors. We hypothesized that CF is characterized by increased arterial stiffness and greater intima-media thickness (IMT).

METHODS

This cross-sectional study assessed the digital volume pulse arterial stiffness index (SI_DVP) using photopletysmography, measured intima-media complex thickness (IMT) at the common carotid artery, and obtained an extended set of clinical and atherosclerosis-related laboratory parameters.

RESULTS

Fifty-five patients with moderate-to-severe CF (mean age 26.3±8.6 years, BMI 20.3±3.1 kg/m2, FEV1 62±26%) and 51 healthy controls (25.1±4.4 years, BMI 21.7±3.0 kg/m2) entered the study. SI_DVP was greater in pancreatic insufficient (PI), but not pancreatic sufficient (PS) CF patients compared with control (7.3±1.8 m/s vs 6.0±1.2 m/s; p=7.1 × 10^-5). IMT was increased in PS (but not PI) participants relative to control (552±69 µm vs 456±95 µm, p=0.0011). SI_DVP was also greater in PI than in PS patients (7.3±1.8 m/s vs 6.3±1.7 m/s, p=0.0232) and IMT was higher in PS compared with PI (552±69 µm vs 453±82 µm, p=0.0002). SI_DVP independently associated with age, PI, the lack of liver cirrhosis, and with Pseudomonas aeruginosa colonization. PS was the only independent correlate of IMT in CF.

CONCLUSIONS

PI patients are at risk of developing general arterial stiffness. PS may relate to carotid IMT thickening, which underscores the need for further study that could lead to reconsideration of dietary guidance in PS CF.

Severe Genotype, Pancreatic Insufficiency and Low Dose of Pancreatic Enzymes Associate with Abnormal Serum Sterol Profile in Cystic Fibrosis

BACKGROUND

Several factors could lead to lipid disturbances observed in cystic fibrosis (CF). This study aimed to assess sterol homeostasis in CF and define potential exogenous and endogenous determinants of lipid dysregulation.

METHODS

The study involved 55 CF patients and 45 healthy subjects (HS). Sterol concentrations (μg/dL) were measured by gas chromatography/mass spectrometry. CF was characterised by lung function, pancreatic status, liver disease and diabetes coexistence, Pseudomonas aeruginosa colonisation and BMI. CFTR genotypes were classified as severe or other.

RESULTS

Campesterol and β-sitosterol concentrations were lower (p = 0.0028 and p < 0.0001, respectively) and lathosterol levels (reflecting endogenous cholesterol biosynthesis) were higher (p = 0.0016) in CF patients than in HS. Campesterol and β-sitosterol concentrations were lower in patients with a severe CFTR genotype, pancreatic insufficiency and lower pancreatic enzyme dose (lipase units/gram of fat). In multiple regression analyses, β-sitosterol and campesterol concentrations were predicted by genotype and pancreatic insufficiency, whereas cholesterol and its fractions were predicted by phytosterol concentrations, age, dose of pancreatic enzymes, nutritional status and genotype.

CONCLUSIONS

Independent determinants of lipid status suggest that malabsorption and pancreatic enzyme supplementation play a significant role in sterol abnormalities. The measurement of campesterol and β-sitosterol concentrations in CF patients may serve for the assessment of the effectiveness of pancreatic enzyme replacement therapy and/or compliance, but further research is required.

An Innovative Lipidomic Workflow to Investigate the Lipid Profile in a Cystic Fibrosis Cell Line

Altered lipid metabolism has been associated to cystic fibrosis disease, which is characterized by chronic lung inflammation and various organs dysfunction. Here, we present the validation of an untargeted lipidomics approach based on high-resolution mass spectrometry aimed at identifying those lipid species that unequivocally sign CF pathophysiology. Of n.13375 mass spectra recorded on cystic fibrosis bronchial epithelial airways epithelial cells IB3, n.7787 presented the MS/MS data, and, after software and manual validation, the final number of annotated lipids was restricted to n.1159. On these lipids, univariate and multivariate statistical approaches were employed in order to select relevant lipids for cellular phenotype discrimination between cystic fibrosis and HBE healthy cells. In cystic fibrosis IB3 cells, a pervasive alteration in the lipid metabolism revealed changes in the classes of ether-linked phospholipids, cholesterol esters, and glycosylated sphingolipids. Through functions association, it was evidenced that lipids variation involves the moiety implicated in membrane composition, endoplasmic reticulum, mitochondria compartments, and chemical and biophysical lipids properties. This study provides a new perspective in understanding the pathogenesis of cystic fibrosis and strengthens the need to use a validated mass spectrometry-based lipidomics approach for the discovery of potential biomarkers and perturbed metabolism.

Cystic fibrosis dyslipidaemia: A cross-sectional study

BACKGROUND

The interest in cystic fibrosis (CF) dyslipidaemia as a potential risk factor for cardiovascular disease is increasing with patients' survival. This study aimed to investigate CF dyslipidaemia, its clinical correlates and links to oxidized low-density lipoprotein (oxLDL), adiponectin, and apolipoprotein E (APOE).

METHODS

This cross-sectional study assessed clinical characteristics of CF, as well as the serum lipid profile, oxLDL, adiponectin, and APOE.

RESULTS

In total, 108 CF subjects were enrolled in this study, with a median age of 22 years, BMI of 20.5 kg/m², FEV1% of 61%, of which 81% were pancreatic insufficient (PI). Healthy subjects (HS; n = 51) were in similar age. Hypocholesterolaemia occurred in 31% of CF subjects and in no HS. Hypertriglyceridaemia concerned 21% of patients (HS: 8%, p = .04), and low HDL-C 45% (HS: 6%, p < .0001). At least one of these three CF dyslipidaemia disturbances was present in 62% of CF subjects, but there were no significant differences in oxLDL, oxLDL/LDL-C ratio, adiponectin, and APOE between CF and HS groups. PI was independently associated with low total cholesterol, LDL-C, and non-high density lipoprotein cholesterol, with age and sex also modifying lipid levels. In CF (n = 42), triglycerides did not correlate with serum tumour necrosis factor α (TNF-α).

CONCLUSIONS

CF dyslipidaemia is highly prevalent and heterogenous. The lipid profile weakly associates with the clinical characteristics of CF as well as oxLDL, adiponectin, and APOE. Further research is needed, especially regarding HDL function in CF, the causes of hypertriglyceridaemia, and the value of essential fatty acid supplementation for CF dyslipidaemia.

Increased Soluble VCAM-1 and Normal P-Selectin in Cystic Fibrosis: a Cross-Sectional Study

Purpose

As life expectancy in cystic fibrosis (CF) increases, questions regarding its potential impact on cardiovascular health arise. Soluble vascular cell adhesion molecule 1 (sVCAM-1), P-selectin (sP-selectin) are proposed as biomarkers of cardiovascular disease. We aimed to: compare their concentrations in clinically stable CF patients and healthy subjects (HS) and verify whether they independently correlate with CF characteristics.

Methods

Serum sVCAM-1 and sP-selectin levels were measured using ELISA. CF was characterized using: forced expiratory volume in 1 s, exocrine pancreatic and CF-related liver disease status, Pseudomonas aeruginosa colonization, serum high-sensitivity C-reactive protein, and body mass index (BMI). CFTR genotypes were classified as severe (classes I and II) or other.

Results

108 CF patients and 51 healthy subjects volunteered for the study. In the CF group BMI was lower (median [IQR]: 20.5 kg/m² [18.4–22.2] vs. 21.6 kg/m² [19.9–23.4], p = 0.02) and hsCRP levels were higher (3.6 mg/L [1.1–7.1] vs. 0.5 mg/dL [0.3–1.0], p < 10⁻¹⁰). While sVCAM-1 concentrations were greater in CF patients (1018 ng/mL [851–1279] vs. 861 ng/mL [806–979], p < 10⁻⁴), sP-selectin levels did not differ (155 ng/mL [129–188] vs. 156 ng/mL [144–177], p = 0.48). None of the multivariable regression models was valid for the prediction of sVCAM-1 and sP-selectin in CF.

Conclusions

We found higher sVCAM-1 concentrations in CF patients than in healthy subjects, which were not explained by CF characteristics. Further research is required to check whether sVCAM-1 is a marker of microangiopathy in CF.