Insight into erythrocyte phospholipid molecular flux in healthy humans and in patients with acute respiratory distress syndrome

In Vivo Cellular Phosphatidylcholine Kinetics of CD15+ Leucocytes and CD3+ T-Lymphocytes in Adults with Acute Respiratory Distress Syndrome

Mammalian cell membranes composed of a mixture of glycerophospholipids, the relative composition of individual phospholipids and the dynamic flux vary between cells. In addition to their structural role, membrane phospholipids are involved in cellular signalling and immunomodulatory functions. In this study, we investigate the molecular membrane composition and dynamic flux of phosphatidylcholines in CD15+ leucocytes and CD3+ lymphocytes extracted from patients with acute respiratory distress syndrome (ARDS). We identified compositional variations between these cell types, where CD15+ cells had relatively higher quantities of alkyl-acyl PC species and CD3+ cells contained more arachidonoyl-PC species. There was a significant loss of arachidonoyl-PC in CD3+ cells in ARDS patients. Moreover, there were significant changes in PC composition and the methyl-D9 enrichment of individual molecular species in CD15+ cells from ARDS patients. This is the first study to perform an in vivo assessment of membrane composition and dynamic changes in immunological cells from ARDS patients.

Development of a new online SPE-HPLC-MS/MS method for the profiling and quantification of sphingolipids and phospholipids in red blood cells - Application to the study of Gaucher's disease

Red blood cells (RBCs) are the subject of clinical attention due to their biological importance. Recently, it has been shown that certain erythrocyte pathologies could be linked to an abnormal lipid composition. In this work, we have developed a simple and fast method using online sample preparation with liquid chromatography coupled to mass spectrometry (SPE-HPLC-MS/MS), to identify a large number of sphingolipids (SL) and phospholipids (PL). The use of online sample preparation considerably reduces analysis times (15 min including extraction and separation of lipids + 2 min for system re-equilibration) and facilitates experimentation while ensuring very good extraction yields. This method was then successfully applied to the quantification of 30 sphingolipids and phospholipids in plasma and erythrocyte extracts from a cohort of individuals with Gaucher disease, treated or not by enzymotherapy. Our results for the study of this disease, led us to establish the lipid profile of the healthy red blood cells, still not very well-known to date. For this, we adopted a semi-targeted approach, based on the use of a triple-quadrupole analyzer and identified more than two hundred different lipid species. These promising results will hopefully enable us to enrich our knowledge of the normal red blood cells lipidome.

Metabolomics profile in acute respiratory distress syndrome by nuclear magnetic resonance spectroscopy in patients with community-acquired pneumonia

Background

Acute respiratory distress syndrome (ARDS) is a challenging clinical problem. Discovering the potential metabolic alterations underlying the ARDS is important to identify novel therapeutic target and improve the prognosis. Serum and urine metabolites can reflect systemic and local changes and could help understanding metabolic characterization of community-acquired pneumonia (CAP) with ARDS.

Methods

Clinical data of patients with suspected CAP at the First Affiliated Hospital of Wenzhou Medical University were collected from May 2020 to February 2021. Consecutive patients with CAP were enrolled and divided into two groups: CAP with and without ARDS groups. ¹H nuclear magnetic resonance-based metabolomics analyses of serum and urine samples were performed before and after treatment in CAP with ARDS (n = 43) and CAP without ARDS (n = 45) groups. Differences metabolites were identifed in CAP with ARDS. Furthermore, the receiver operating characteristic (ROC) curve was utilized to identify panels of significant metabolites for evaluating therapeutic effects on CAP with ARDS. The correlation heatmap was analyzed to further display the relationship between metabolites and clinical characteristics.

Results

A total of 20 and 42 metabolites were identified in the serum and urine samples, respectively. Serum metabolic changes were mainly involved in energy, lipid, and amino acid metabolisms, while urine metabolic changes were mainly involved in energy metabolism. Elevated levels of serum 3-hydroxybutyrate, lactate, acetone, acetoacetate, and decreased levels of serum leucine, choline, and urine creatine and creatinine were detected in CAP with ARDS relative to CAP without ARDS. Serum metabolites 3-hydroxybutyrate, acetone, acetoacetate, citrate, choline and urine metabolite 1-methylnicotinamide were identified as a potential biomarkers for assessing therapeutic effects on CAP with ARDS, and with AUCs of 0.866 and 0.795, respectively. Moreover, the ROC curve analysis revealed that combined characteristic serum and urine metabolites exhibited a better classification system for assessing therapeutic effects on CAP with ARDS, with a AUC value of 0.952. In addition, differential metabolites strongly correlated with clinical parameters in patients with CAP with ARDS.

Conclusions

Serum- and urine-based metabolomics analyses identified characteristic metabolic alterations in CAP with ARDS and might provide promising circulatory markers for evaluating therapeutic effects on CAP with ARDS.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12931-022-02075-w.

A choline-releasing glycerophosphodiesterase essential for phosphatidylcholine biosynthesis and blood stage development in the malaria parasite

The malaria parasite Plasmodium falciparum synthesizes significant amounts of phospholipids to meet the demands of replication within red blood cells. De novo phosphatidylcholine (PC) biosynthesis via the Kennedy pathway is essential, requiring choline that is primarily sourced from host serum lysophosphatidylcholine (lysoPC). LysoPC also acts as an environmental sensor to regulate parasite sexual differentiation. Despite these critical roles for host lysoPC, the enzyme(s) involved in its breakdown to free choline for PC synthesis are unknown. Here, we show that a parasite glycerophosphodiesterase (PfGDPD) is indispensable for blood stage parasite proliferation. Exogenous choline rescues growth of PfGDPD-null parasites, directly linking PfGDPD function to choline incorporation. Genetic ablation of PfGDPD reduces choline uptake from lysoPC, resulting in depletion of several PC species in the parasite, whilst purified PfGDPD releases choline from glycerophosphocholine in vitro. Our results identify PfGDPD as a choline-releasing glycerophosphodiesterase that mediates a critical step in PC biosynthesis and parasite survival.

Lipotoxicity Disrupts Erythrocyte Function: A Perspective

BACKGROUND

Lipid accumulation in the liver, skeletal and cardiac muscle, kidneys and pancreas causes cell dysfunction, death and inflammation, a biological phenomenon named lipotoxicity. Erythrocytes participate in the transport of lipids in the circulation, and their lipidome is determined by exchange with blood components.

OBJECTIVE

The objective of this study is to summarize the current knowledge regarding the effect of toxic lipid accumulation in erythrocytes.

RESULTS

Erythrocyte lipidome is altered in lipotoxic diseases, such as fatty liver disease, heart failure and diabetes. In addition, ceramide, lysophosphatidylcholine, lysophosphatidic acid, palmitic acid and free cholesterol induce erythrocyte malfunction.

CONCLUSION

Erythrocytes are an additional cell target of lipotoxicity. Further exploration of the implicated molecular mechanisms could lead to novel therapeutic targets for cardiometabolic and hematological diseases.

The Fatty Acid-Based Erythrocyte Membrane Lipidome in Dogs with Chronic Enteropathy

Canine chronic enteropathies (CEs) are inflammatory processes resulting from complex interplay between the mucosal immune system, intestinal microbiome, and dietary components in susceptible dogs. Fatty acids (FAs) play important roles in the regulation of physiologic and metabolic pathways and their role in inflammation seems to be dual, as they exhibit pro-inflammatory and anti-inflammatory functions. Analysis of red blood cell (RBC) membrane fatty acid profile represents a tool for assessing the quantity and quality of structural and functional molecular components. This study was aimed at comparing the FA membrane profile, determined by Gas Chromatography and relevant lipid parameter of 48 CE dogs compared with 68 healthy dogs. In CE patients, the levels of stearic (p < 0.0001), dihomo-gamma-linolenic, eicosapentaenoic (p = 0.02), and docosahexaenoic (p = 0.02) acids were significantly higher, and those of palmitic (p < 0.0001) and linoleic (p = 0.0006) acids were significantly lower. Non-responder dogs presented higher percentages of vaccenic acid (p = 0.007), compared to those of dogs that responded to diagnostic trials. These results suggest that lipidomic status may reflect the "gut health", and the non-invasive analysis of RBC membrane might have the potential to become a candidate biomarker in the evaluation of dogs affected by CE.

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.

Altered Levels of Desaturation and ω-6 Fatty Acids in Breast Cancer Patients' Red Blood Cell Membranes

Red blood cell (RBC) membrane can reflect fatty acid (FA) contribution from diet and biosynthesis. In cancer, membrane FAs are involved in tumorigenesis and invasiveness, and are indicated as biomarkers to monitor the disease evolution as well as potential targets for therapies and nutritional strategies. The present study provides RBC membrane FA profiles in recently diagnosed breast cancer patients before starting chemotherapy treatment. Patients and controls were recruited, and their dietary habits were collected. FA lipidomic analysis of mature erythrocyte membrane phospholipids in blood samples was performed. Data were adjusted to correct for the effects of diet, body mass index (BMI), and age, revealing that patients showed lower levels of saturated fatty acids (SFA) and higher levels of monounsaturated fatty acid, cis-vaccenic (25%) than controls, with consequent differences in desaturase enzymatic index (∆9 desaturase, -13.1%). In the case of polyunsaturated fatty acids (PUFA), patients had higher values of ω-6 FA (C18:2 (+11.1%); C20:4 (+7.4%)). RBC membrane lipidomic analysis in breast cancer revealed that ω-6 pathways are favored. These results suggest new potential targets for treatments and better nutritional guidelines.

Fatty Acids and Membrane Lipidomics in Oncology: A Cross-Road of Nutritional, Signaling and Metabolic Pathways

Fatty acids are closely involved in lipid synthesis and metabolism in cancer. Their amount and composition are dependent on dietary supply and tumor microenviroment. Research in this subject highlighted the crucial event of membrane formation, which is regulated by the fatty acids' molecular properties. The growing understanding of the pathways that create the fatty acid pool needed for cell replication is the result of lipidomics studies, also envisaging novel fatty acid biosynthesis and fatty acid-mediated signaling. Fatty acid-driven mechanisms and biological effects in cancer onset, growth and metastasis have been elucidated, recognizing the importance of polyunsaturated molecules and the balance between omega-6 and omega-3 families. Saturated and monounsaturated fatty acids are biomarkers in several types of cancer, and their characterization in cell membranes and exosomes is under development for diagnostic purposes. Desaturase enzymatic activity with unprecedented de novo polyunsaturated fatty acid (PUFA) synthesis is considered the recent breakthrough in this scenario. Together with the link between obesity and cancer, fatty acids open interesting perspectives for biomarker discovery and nutritional strategies to control cancer, also in combination with therapies. All these subjects are described using an integrated approach taking into account biochemical, biological and analytical aspects, delineating innovations in cancer prevention, diagnostics and treatments.

High Variability in Erythrocyte, Plasma and Whole Blood EPA and DHA Levels in Response to Supplementation

(1) Aim: the aim of this secondary analysis was to report the variability in response to n-3 long chain polyunsaturated fatty acids (LCPUFA) supplementation in erythrocytes, plasma and whole blood of a previously published dose response study. (2) Methods: a randomized, double-blind, placebo-controlled trial of parallel design was conducted, whereby pre-menopausal women were randomly assigned to consume 0, 0.35, 0.7 or 1 g/day of supplemental eicosapentaenoic acid (EPA) plus docosahexaenoic acid (DHA). Fasted blood samples were taken at baseline and after eight weeks intervention. Erythrocyte, plasma and whole blood fatty acids were extracted using the method of Lepage and Roy and analysed using gas chromatography. (3) Results: There were significant increases in EPA plus DHA levels in the 0.7 g and 1 g dose groups, with the highest increase with the 1 g dose notably: in erythrocytes (from 5.69% to 7.59%), plasma (from 2.94% to 5.48%) and in whole blood (from 3.81% to 6.03%). There was high variability in response to the supplement in erythrocytes, plasma and whole blood across the different doses. (4) Conclusion: there is high individual variability in n-3 LCPUFA levels in response to n-3 LCPUFA supplementation, which should be taken into account in clinical trials using n-3 LCPUFA supplements.