Fatty acids, membrane viscosity, serotonin and ischemic heart disease

Assessing hypoxic damage to placental trophoblasts by measuring membrane viscosity of extracellular vesicles

INTRODUCTION

As highly sophisticated intercellular communication vehicles in biological systems, extracellular vesicles (EVs) have been investigated as both promising liquid biopsy-based disease biomarkers and drug delivery carriers. Despite tremendous progress in understanding their biological and physiological functions, mechanical characterization of these nanoscale entities remains challenging due to the limited availability of proper techniques. Especially, whether damage to parental cells can be reflected by the mechanical properties of their EVs remains unknown.

METHODS

In this study, we characterized membrane viscosities of different types of EVs collected from primary human trophoblasts (PHTs), including apoptotic bodies, microvesicles and small extracellular vesicles, using fluorescence lifetime imaging microscopy (FLIM). The biochemical origin of EV membrane viscosity was examined by analyzing their phospholipid composition, using mass spectrometry.

RESULTS

We found that different EV types derived from the same cell type exhibit different membrane viscosities. The measured membrane viscosity values are well supported by the lipidomic analysis of the phospholipid compositions. We further demonstrate that the membrane viscosity of microvesicles can faithfully reveal hypoxic injury of the human trophoblasts. More specifically, the membrane of PHT microvesicles released under hypoxic condition is less viscous than its counterpart under standard culture condition, which is supported by the reduction in the phosphatidylethanolamine-to-phosphatidylcholine ratio in PHT microvesicles.

DISCUSSION

Our study suggests that biophysical properties of released trophoblastic microvesicles can reflect cell health. Characterizing EV's membrane viscosity may pave the way for the development of new EV-based clinical applications.

Assessment of changes in membrane properties of platelets from patients with chronic myeloid leukaemia in different stages of the disease

Patients with chronic myeloproliferative leukemia (CML) have frequent haemorrhage and/or thrombosis in their medical history. The mechanisms of these major and life-threatening complications remain unclear. Membrane organization influences many of the unique cellular functions and is strongly correlated, among other factors, to the membrane lipid composition; it may be evaluated by following up the membrane fluidity and aggregation properties of the platelet. In this study, we evaluated the platelet aggregation, the expression of platelet surface receptors, the membrane fluidity (as evaluated by fluorescence anisotropy) and its correlation to reactive oxygen species (ROS) production, in patients with chronic myeloid leukaemia (CML). It was found that the patients in accelerated and blastic phase of CML present an altered platelet aggregation response to all reagents except for ristocetin as compared with chronic phase group, which shows only epinephrine-altered response. We also found that BCR/ABL transcript leads to higher levels of ROS in accelerated and blastic CML phases. Patients without molecular remission have lower platelet membrane fluidity. We obtained a positive correlation between ROS level and membrane fluorescence anisotropy changes. The CD41 expression was decreased in CML patients and P selectin expression was found to be higher in these patients than in healthy volunteers. Platelets of CML patients have altered aggregation parameters in accelerated and blastic phases, in which BCR/ABL transcript level is increased. The increased level of ROS in CML patients without molecular remission is associated with a decrease in fluidity of platelet membrane and expression of CD41/CD61 receptors. These findings may contribute to understanding the mechanism of the altered platelet response reported in CML patients.

Long-chain n-3 polyunsaturated fatty acid dietary recommendations are moderately efficient in optimizing their status in healthy middle-aged subjects with low fish consumption: a cross-over study

Several dietary recommendations have been made for marine n-3 polyunsaturated fatty acid (PUFA) intake; however, the effectiveness of these fatty acids has not been thoroughly examined. The aim of this study was to investigate whether public-aimed dietary recommendations for long-chain n-3 PUFA from oily fish or fish oil supplements are efficient in optimizing their status in red blood cells (RBCs) and platelets of healthy middle-aged subjects with low customary fish consumption. In a randomized, cross-over trial conducted over an 8-week period and separated by a 6-month washout period, 33 participants received an oily fish (salmon), providing 274 mg eicosapentaenoic acid (EPA) + 671 mg docosahexaenoic acid (DHA) per day, or a commercial fish oil supplement, providing 396 mg EPA + 250 mg DHA per day. Blood samples were collected before and after each intervention period, and RBCs and platelets were used for analysis of fatty acids. After 8 weeks, there were significant increases in EPA and DHA content in RBCs and platelets with both salmon and fish oil capsules. The increase in EPA in both RBCs and platelets was higher with capsules, whereas the increase in DHA in both RBCs and platelets was higher with salmon. In spite of the quantitative and qualitative differences between n-3 fatty acid profiles in salmon and the fish oil supplement, the overall incorporation of these fatty acids into RBCs and platelets did not differ in our short-term study (P > .05). The sum of EPA + DHA significantly increased in both compartments following dietary recommendations for oily fish and fish oil supplements intake in middle-aged healthy subjects with low baseline long-chain n-3 PUFA status, although targeted values with optimal cardioprotective effect of more than 8% were not achieved.

Depression, osteoporosis, serotonin and cell membrane viscosity between biology and philosophical anthropology

Due to the relationship between biology and culture, we believe that depression, understood as a cultural and existential phenomenon, has clear markers in molecular biology. We begin from an existential analysis of depression constituting the human condition and then shift to analysis of biological data confirming, according to our judgment, its original (ontological) structure. In this way philosophy is involved at the anthropological level, in as much as it detects the underlying meanings of depression in the original biological-cultural horizon of human life. Considering the integration of knowledge it is the task of molecular biology to identify the aforementioned markers, to which the existential aspects of depression are linked to. In particular, recent works show the existence of a link between serotonin and osteoporosis as a result of a modified expression of the low-density lipoprotein receptor-related protein 5 gene. Moreover, it is believed that the hereditary or acquired involvement of tryptophan hydroxylase 2 (Tph2) or 5-hydroxytryptamine transporter (5-HTT) is responsible for the reduced concentration of serotonin in the central nervous system, causing depression and affective disorders. This work studies the depression-osteoporosis relationship, with the aim of focusing on depressive disorders that concern the quantitative dynamic of platelet membrane viscosity and interactome cytoskeleton modifications (in particular Tubulin and Gsα protein) as a possible condition of the involvement of the serotonin axis (gut, brain and platelet), not only in depression but also in connection with osteoporosis.