Changes of the Fatty Acid Profile in Erythrocyte Membranes of Patients following 6-Month Dietary Intervention Aimed at the Regression of Nonalcoholic Fatty Liver Disease (NAFLD)

Long-term fasting induces a remodelling of fatty acid composition in erythrocyte membranes

INTRODUCTION

Long-term fasting (LF) activates an adaptative response to switch metabolic fuels from food glucose to lipids stored in adipose tissues. The increase in free fatty acid (FFA) oxidation during fasting triggers health benefits. We questioned if the changes in lipid metabolism during LF could affect lipids in cell membranes in humans. We thus analysed the FA composition in erythrocyte membranes (EM) during 12.6 ± 3.5 days of LF and 1 month after food reintroduction.

METHODS

A total of 98 subjects out of three single-arm interventional studies underwent a medical supervised long-term fasting (12.6 ± 3.5 days) programme. The distribution pattern of 26 FA as well as the HS-Omega-3 Index were assessed in the EM using gas chromatography.

RESULTS

Eighteen of 26 FA showed significant changes. Within the group of saturated FA, myristic (14:0) and stearic acid (18:0) decreased while palmitic (16:0) and arachid acid (20:0) increased. While most monounsaturated FA increased, trans fatty acids decreased or remained unchanged. Within the polyunsaturated FA, arachidonic (20:4n6) and docosahexaenoic (22:6n3) acid increased, while linoleic (18:2n6), alpha-linolenic (18:3n3) and eicosapentaenoic acid (20:5n3) decreased. Consequently, the HS-Omega-3 Index increased. 11 out of the 18 FA with significant changes returned to baseline levels 1 month afterwards. Levels of linoleic and alpha-linolenic acid increased over baseline levels.

CONCLUSIONS

Long-term fasting triggers changes in the FA composition of EM.

Fatty acid composition but not quantity is an important indicator of non-alcoholic fatty liver disease: a systematic review

BACKGROUND

There is still paucity on the effects of dietary and supplemental fatty acid on non-alcoholic fatty liver disease (NAFLD). The aim of this review is to systematically review and summarise the effect of fatty acids intake on liver-related outcomes in adult patients with NAFLD.

METHODS

The review was conducted using Cochrane CENTRAL Library, Scopus, Embase, MEDLINE, PubMed, and Web of Science. A total of 2786 records were identified, and of these, 36 studies (31 were randomised control trials (RCTs), and 5 were case-control studies) were included. Quality assessment was conducted using the Revised Cochrane Risk of Bias tool and Joanna Briggs Institute checklists.

RESULTS

Of 36 articles, 79% of RCTs and 66% of case-control studies had a low risk of bias. Potential heterogeneity has been observed in assessment of liver-related outcomes. According to the RCTs, there was moderate evidence (3/6 studies) that a diet characterised by a high MUFA, PUFA and low SFA showed reduced liver fat and stiffness. The using of culinary fats that are high in MUFA (4/6 studies) reduces liver steatosis. n-3 PUFA supplementation in combination with a hypocaloric or heart healthy diet with a low SFA improved liver enzyme level (5/14 studies) and steatosis score (3/14 studies).

CONCLUSIONS

Effects on NAFLD parameters, including liver fat content (assessed via magnetic resonance imaging/spectroscopy), stiffness and steatosis score (assessed by ultrasonography), were primarily related to fatty acid composition independent of energy intake. Further investigation is needed to determine the mechanism of specific fatty acid on the accumulation of liver fat.

Associations of fatty acids composition and estimated desaturase activities in erythrocyte phospholipids with biochemical and clinical indicators of cardiometabolic risk in non-diabetic Serbian women: the role of level of adiposity

Introduction

Fatty acids (FAs) composition and desaturase activities can be altered in different metabolic conditions, but the adiposity-independent associations with clinical and biochemical indicators of cardiometabolic risk are still unclear. This study aimed to analyze the associations of FAs composition and estimated desaturase activities with anthropometric, clinical, and biochemical cardiometabolic risk indicators in non-diabetic Serbian women, and to investigate if these associations were independent of the level of adiposity and other confounders.

Methods

In 76 non-diabetic, otherwise healthy Serbian women, aged 24-68 years, with or without metabolic syndrome or obesity (BMI=23.6±5.6 kg/m2), FA composition in erythrocyte phospholipids was measured by gas-liquid chromatography. Desaturase activities were estimated from product/precursor FAs ratios (D9D:16:1n-7/16:0; D6D:20:3n-6/18:2n-6; D5D:20:4n-6/20:3n-6). Correlations were made with anthropometric, biochemical (serum glucose, triacylglycerols, LDL-C, HDL-C, ALT, AST, and their ratios) and clinical (blood pressure) indicators of cardiometabolic risk. Linear regression models were performed to test the independence of these associations.

Results

Estimated desaturase activities and certain FAs were associated with anthropometric, clinical and biochemical indicators of cardiometabolic risk: D9D, D6D, 16:1n-7 and 20:3n-6 were directly associated, while D5D and 18:0 were inversely associated. However, the associations with clinical and biochemical indicators were not independent of the associations with the level of adiposity, since they were lost after controlling for anthropometric indices. After controlling for multiple confounders (age, postmenopausal status, education, smoking, physical activity, dietary macronutrient intakes, use of supplements, alcohol consumption), the level of adiposity was the most significant predictor of desaturase activities and aforementioned FAs levels, and mediated their association with biochemical/clinical indicators. Vice versa, desaturase activities predicted the level of adiposity, but not other components of cardiometabolic risk (if the level of adiposity was accounted). While the associations of anthropometric indices with 16:1n-7, 20:3n-6, 18:0 and D9D and D6D activities were linear, the associations with D5D activity were the inverse U-shaped. The only adiposity-independent association of FAs profiles with the indicators of cardiometabolic risk was a positive association of 20:5n-3 with ALT/AST ratio, which requires further exploration.

Discussion

Additional studies are needed to explore the mechanisms of the observed associations.

Application of metabolomics in the diagnosis of non-alcoholic fatty liver disease and the treatment of traditional Chinese medicine

Non-alcoholic fatty liver disease (NAFLD) is the most common chronic liver disease around the world, and it often coexists with insulin resistance-related diseases including obesity, diabetes, hyperlipidemia, and hypertension, which seriously threatens human health. Better prevention and treatment strategies are required to improve the impact of NAFLD. Although needle biopsy is an effective tool for diagnosing NAFLD, this method is invasive and difficult to perform. Therefore, it is very important to develop more efficient approaches for the early diagnosis of NAFLD. Traditional Chinese medicine (TCM) can play a certain role in improving symptoms and protecting target organs, and its mechanism of action needs to be further studied. Metabolomics, the study of all metabolites that is thought to be most closely associated with the patients' characters, can provide useful clinically biomarkers that can be applied to NAFLD and may open up new methods for diagnosis. Metabolomics technology is consistent with the overall concept of TCM, and it can also be used as a potential mechanism to explain the effects of TCM by measuring biomarkers by metabolomics. Based on PubMed/MEDLINE and other databases, this paper retrieved relevant literature NAFLD and TCM intervention in NAFLD using metabolomics technology in the past 5 years were searched, and the specific metabolites associated with the development of NAFLD and the potential mechanism of Chinese medicine on improving symptoms were summarized.

Roles of Palmitoleic Acid and Its Positional Isomers, Hypogeic and Sapienic Acids, in Inflammation, Metabolic Diseases and Cancer

In the last few years, the monounsaturated hexadecenoic fatty acids are being increasingly considered as biomarkers of health with key functions in physiology and pathophysiology. Palmitoleic acid (16:1n-7) and sapienic acid (16:1n-10) are synthesized from palmitic acid by the action of stearoyl-CoA desaturase-1 and fatty acid desaturase 2, respectively. A third positional isomer, hypogeic acid (16:1n-9) is produced from the partial β-oxidation of oleic acid. In this review, we discuss the current knowledge of the effects of palmitoleic acid and, where available, sapienic acid and hypogeic acid, on metabolic diseases such as diabetes, cardiovascular disease, and nonalcoholic fatty liver disease, and cancer. The results have shown diverse effects among studies in cell lines, animal models and humans. Palmitoleic acid was described as a lipokine able to regulate different metabolic processes such as an increase in insulin sensitivity in muscle, β cell proliferation, prevention of endoplasmic reticulum stress and lipogenic activity in white adipocytes. Numerous beneficial effects have been attributed to palmitoleic acid, both in mouse models and in cell lines. However, its role in humans is not fully understood, and is sometimes controversial. Regarding sapienic acid and hypogeic acid, studies on their biological effects are still scarce, but accumulating evidence suggests that they also play important roles in metabolic regulation. The multiplicity of effects reported for palmitoleic acid and the compartmentalized manner in which they often occur, may suggest the overlapping actions of multiple isomers being present at the same or neighboring locations.

Nonalcoholic Fatty Liver Disease: Focus on New Biomarkers and Lifestyle Interventions

Nonalcoholic fatty liver disease (NAFLD) is considered a hepatic manifestation of metabolic syndrome, characterized from pathological changes in lipid and carbohydrate metabolism. Its main characteristics are excessive lipid accumulation and oxidative stress, which create a lipotoxic environment in hepatocytes leading to liver injury. Recently, many studies have focused on the identification of the genetic and epigenetic modifications that also contribute to NAFLD pathogenesis and their prognostic implications. The present review is aimed to discuss on cellular and metabolic alterations associated with NAFLD, which can be helpful to identify new noninvasive biomarkers. The identification of accumulated lipids in the cell membranes, as well as circulating cytokeratins and exosomes, provides new insights in understanding of NAFLD. This review also suggests that lifestyle modifications remain the main prevention and/or treatment for NAFLD.

Red Blood Cell Dysfunction in Non-Alcoholic Fatty Liver Disease: Marker and Mediator of Molecular Mechanisms

Despite efforts to unravel the pathogenetic mechanisms of non-alcoholic fatty liver disease (NAFLD), there is still a need for approved treatments and biomarkers. Interestingly, red blood cells present alterations in their characteristics during NAFLD. The phosphatidylcholine to phosphatidylethanolamine ratio, fatty acid profile, red blood cell count and red cell distribution width reflect molecular changes that are taking place in the liver. In addition, glycosylated hemoglobin, chemokine binding and release, and phosphatidylserine exposure actively participate in NAFLD pathogenesis. In this review, we describe the neglected red blood cell dysfunction in NAFLD, with the aim to unveil potent biomarkers and therapeutic targets.

Effect of pemafibrate on fatty acid levels and liver enzymes in non-alcoholic fatty liver disease patients with dyslipidemia: A single-arm, pilot study

AIM

Dyslipidemia (DL) is commonly associated with non-alcoholic fatty liver disease (NAFLD). Pemafibrate, a selective peroxisome proliferator activated receptor α modulator (SPPARMα), has been shown to improve liver function among patients with DL. The aim of this single-arm prospective study is to evaluate the efficacy of pemafibrate in NAFLD patients with DL.

METHODS

Twenty NAFLD patients with DL who received pemafibrate (0.1 mg) twice a day for 12 weeks were prospectively enrolled in this study. The primary end-point was change in serum alanine aminotransferase (ALT) levels from baseline to week 12.

RESULTS

Serum ALT levels decreased from 75.1 IU/L at baseline to 43.6 IU/L at week 12 (P = 0.001). Significant improvements in triglyceride, high-density lipoprotein cholesterol, total fatty acid, saturated fatty acid (SFA), and unsaturated fatty acid were also noted. The serum level of remnant-like protein cholesterol, SFA, and polyunsaturated / saturated fatty acid ratio (PUFA / SFA ratio) at baseline were correlated with change in ALT level (r = -0.53, r = -0.57, and r = 0.46, respectively). Change in PUFA and change in PUFA / SFA ratio were negatively correlated with change in ALT level (r = -0.49 and r = -0.53). No hepatic or renal adverse events were reported.

CONCLUSIONS

Selective peroxisome proliferator activated receptor α could be a promising novel agent for treatment of NAFLD patients with DL by regulating fatty acid composition. A further long-term large-scale trial is warranted to confirm the efficacy of SPPARMα on NAFLD with DL.

Comparison of Erythrocyte Membrane Lipid Profiles between NAFLD Patients with or without Hyperlipidemia

Nonalcoholic fatty liver disease (NAFLD) and hyperlipidemia (HL) are common metabolic disorders due to overnutrition and obesity. NAFLD is often associated with hyperlipidemia. The aim of this study was to identify and compare the erythrocyte membrane lipids profile in NAFLD patients with or without HL. Methods. A total of 112 subjects (with similar age and body mass index) were divided into four groups: (1) normal controls, (2) NAFLD alone, (3) HL alone, and (4) NAFLD combined with HL (NAFLD + HL). Lipid was extracted from the erythrocyte membrane, and lipid profiles of subjects were analyzed by liquid chromatography mass spectrometry (LC-MS). Results. Data sets from 103 subjects were adopted for lipidomic analysis. Significant changes of lipid species were observed in patient groups, especially in the HL group and NAFLD + HL group. The HL group showed increased level of most lipid species, and decreased level of most lipid species was observed in the NAFLD + HL group. The weight percent of myristic acid, stearic acid, erucic acid, and docosahexaenoic acid also showed distinct variation between different groups. Conclusions. NAFLD, HL, and NAFLD + HL all had an impact on lipid profiling of the erythrocyte membrane. The influence of NAFLD alone is less important compared with HL. Some lipids should be highlighted because of their specific role in cell function and systemic metabolism.

Is the Fatty Acids Profile in Blood a Good Predictor of Liver Changes? Correlation of Fatty Acids Profile with Fatty Acids Content in the Liver

BACKGROUND

Existing data show a correlation between the profile of fatty acids, liver, and blood. Therefore, the aim of our study was to investigate the correlation between the fatty acids profile in blood pallets and the liver.

METHODS

The experiment was performed on 60 eight-week-old male Sprague-Dawley rats. The study group (n = 30, 5 groups, 6 rats each) received a cholesterol diet; the control group (n = 30, 5 groups, 6 rats each) received standard food for laboratory rats. The rats from both the study and control groups were sacrificed after 2, 4, 8, 12, and 16 weeks of dietary exposure. The fatty acids profile was measured using gas chromatography (GC).

RESULTS

In both the control and study group, the highest correlations were observed in palmitoleic acid (RHO = 0.68), heptadecanoic acid (RHO = 0.65), vaccenic acid (RHO = 0.72), eicosapentaenoic acid (RHO = 0.68), docosapentaenoic acid (RHO = 0.77), and docosahexaenoic (RHO = 0.77). Among liver indexes, the highest correlations were desaturase-18 (0.61).

CONCLUSIONS

Fatty acids profile is a sensitive marker of the development of potentially pathological changes in the liver. The potential markers of fatty liver are: oleic acid, vaccenic acid, EPA, DHA, docosapentaenoic acid, and desaturase index (SCD-18 index).

Fatty Acid Profile of Postmenopausal Women Receiving, and Not Receiving, Hormone Replacement Therapy

Menopause, the permanent cessation of the menstrual cycle, marks the end of a woman's reproductive lifespan. Menopausal hormonal therapy (MHT) can potentially skew the fatty acid profile increasing the risk for developing metabolic diseases and disorders of skeletal, gastrointestinal, and nervous systems. The aim of this study was to investigate the fatty acid profile of postmenopausal women receiving, and not receiving, hormone replacement therapy. A total of 156 healthy women with a mean age of 60 participated in this cross-sectional study. Gas chromatography with an Agilent Technologies 7890A GC system was used to determine fatty acid content. Statistical analysis was conducted using R software, version 3.4.1. Women receiving MHT had significantly higher (p < 0.05) concentrations of C14:0 and C16:0. MHT was found to be associated with a tendency (p = 0.053) to diminish concentrations of C18:1n-9, C20:4, and all unsaturated fatty acids (p < 0.05). The longer MHT was used, the higher the concentration of C24:1 (p = 0.04) and the lower the concentration of C18:2n-6 (p = 0.03).