The Anti-inflammatory Properties of Food Polar Lipids

Polar lipids modify Alzheimer's Disease pathology by reducing astrocyte pro-inflammatory signaling through platelet-activating factor receptor (PTAFR) modulation

BACKGROUND

Pro-inflammatory processes triggered by the accumulation of extracellular amyloid beta (Aβ) peptides are a well-described pathology in Alzheimer's disease (AD). Activated astrocytes surrounding Aβ plaques contribute to inflammation by secreting proinflammatory factors. While astrocytes may phagocytize Aβ and contribute to Aβ clearance, reactive astrocytes may also increase Aβ production. Therefore, identifying factors that can attenuate astrocyte activation and neuroinflammation and how these factors influence pro-inflammatory pathways is important for developing therapeutic and preventive strategies in AD. Here, we identify the platelet-activating factor receptor (PTAFR) pathway as a key mediator of astrocyte activation. Intriguingly, several polar lipids (PLs) have exhibited anti-inflammatory protective properties outside the central nervous system through their inhibitory effect on the PTAFR pathway. Thus, we additionally investigated whether different PLs also exert inhibitory effects on the PAF pathway in astrocytes and whether their presence influences astrocytic pro-inflammatory signaling and known AD pathologies in vitro.

METHODS

PLs from salmon and yogurt were extracted using novel food-grade techniques and their fatty acid profile was determined using LC/MS. The effect of PLs on parameters such as astrocyte activation and generation of oxygen species (ROS) was assessed. Additionally, effects of the secretome of astrocytes treated with these polar lipids on aged neurons was measured.

RESULTS

We show that PLs obtained from salmon and yogurt lower astrocyte activation, the generation of reactive oxygen species (ROS), and extracellular Aβ accumulation. Cell health of neurons exposed to the secretome of astrocytes treated with salmon-derived PLs and Aβ was less affected than those treated with astrocytes exposed to Aβ only.

CONCLUSION

Our results highlight a novel underlying mechanism, why consuming PL-rich foods such as fish and dairy may reduce the risk of developing dementia and associated disorders.

Portulaca oleracea, a rich source of polar lipids: Chemical profile by LC-ESI/LTQOrbitrap/MS/MSn and in vitro preliminary anti-inflammatory activity

Considering the ongoing interest in foods rich in nutrients like polyunsaturated fatty acids and bioactive polar lipids, the chemical and biological investigation of Portulaca oleracea (purslane), a herbaceous plant typically appreciated in Mediterranean and Asiatic diet, was carried out. The LC-ESI/HRMS/MSⁿ analysis of extracts and lipid enriched fractions of purslane edible parts provided a comprehensive polar lipid profile, ranging from linear and cyclic oxylipins to high molecular weight lipids including glycolipids, phospholipids and sphingolipids. The evaluation of the anti-inflammatory potential by in vitro reporter gene assays highlighted the ability of purslane lipid enriched fractions, at a concentration of 20 µg/ml, to inhibit the TNF-α-stimulated NF-kB pathway by 30-40% and to activate PPAR-ɣ and Nrf2 transcription factors to the same extent or more than the positive control, respectively. Altogether, these results encourage to revalue purslane in human nutrition as a source of bioactive polar lipids.

Oat Polar Lipids Improve Cardiometabolic-Related Markers after Breakfast and a Subsequent Standardized Lunch: A Randomized Crossover Study in Healthy Young Adults

It has been suggested that intake of polar lipids may beneficially modulate various metabolic variables. The purpose of this study was to evaluate the effect of oat polar lipids on postprandial and second meal glycemic regulation, blood lipids, gastrointestinal hormones, and subjective appetite-related variables in healthy humans. In a randomized design, twenty healthy subjects ingested four liquid cereal-based test beverages (42 g of available carbohydrates) containing: i. 30 g of oat oil with a low concentration (4%) of polar lipids (PLL), ii. 30 g of oat oil containing a high concentration (40%) of polar lipids (PLH), iii. 30 g of rapeseed oil (RSO), and iv. no added lipids (NL). The products were served as breakfast meals followed by a standardized lunch. Test variables were measured at fasting and during 3 h after breakfast and two additional hours following a standardized lunch. PLH reduced glucose and insulin responses after breakfast (0-120 min) compared to RSO, and after lunch (210-330 min) compared to RSO and PLL (p < 0.05). Compared to RSO, PLH resulted in increased concentrations of the gut hormones GLP-1 and PYY after the standardized lunch (p < 0.05). The results suggest that oat polar lipids have potential nutraceutical properties by modulating acute and second meal postprandial metabolic responses.

Thrombosis and COVID-19: The Potential Role of Nutrition

Severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), responsible for the coronavirus disease (COVID-19), is a contagion that has rapidly spread around the globe. COVID-19 has caused significant loss of life and disrupted global society at a level never before encountered. While the disease was predominantly characterized by respiratory symptoms initially, it became clear that other systems including the cardiovascular and neurological systems were also involved. Several thrombotic complications were reported including venous thrombosis, vasculitis, cardiomyopathy, and stroke. Thrombosis and inflammation are implicated in various non-communicable diseases (NCDs). This is of significant concern as people with pre-existing conditions such as cardiovascular disorders, renal disorders, obesity, metabolic syndrome, and diabetes are at greater risk of severe COVID-19 infection. Consequently, the research surrounding the use of anticoagulants, antiplatelet, and antithrombotic strategies for prophylaxis and treatment of COVID-19 is of critical importance. The adoption of a healthy diet, physical exercise, and lifestyle choices can reduce the risk factors associated with NCDs and the thrombo-inflammatory complications. In this review, these thrombotic complications and potential foods, nutraceuticals, and the antithrombotic constituents within that may prevent the onset of severe thrombotic complications as a result of infection are discussed. While nutrition is not a panacea to tackle COVID-19, it is apparent that a patient's nutritional status may affect patient outcomes. Further intensive research is warranted to reduce to incidence of thrombotic complications.

Structural Elucidation of Irish Ale Bioactive Polar Lipids with Antithrombotic Properties

The structures of bioactive polar lipids (PLs) of Irish ale with potent antithrombotic and cardioprotective properties were elucidated. Ale PL was fractionated by preparative thin layer chromatography (TLC) into subclasses, and their antithrombotic effect was assessed against human platelet aggregation induced by the pro-inflammatory mediator, platelet-activating factor (PAF). The fatty acid content and the overall structures of ale PL were elucidated by liquid chromatography mass spectrometry (LC-MS). Phosphatidylcholines (PC) and molecules of the sphingomyelin (SM) family exhibited the strongest anti-PAF effects, followed by phosphatidylethanolamines (PE). PC contained higher amounts of omega-3 polyunsaturated fatty acids (n-3 PUFA) and thus the lowest n-6/n-3 ratio. Bioactive diacyl and alkyl-acyl PC and PE molecules bearing n-3 PUFA at their sn-2 position, especially docosahexaenoic acid (DHA) and α-linolenic acid (ALA) but mostly oleic acid (OA), were identified in both PC and PE subclasses. Eicosapentaenoic acid (EPA) was present only in bioactive PC molecules and not in PE, explaining the lower anti-PAF effects of PE. Bioactive sphingolipid and glycolipid molecules with reported anti-inflammatory and anti-tumour properties, such as specific ceramides and glucosylcerebrosides with sphingosine, phytosphingosine and dihydrosphingosine bases but also specific monogalactodiglycerides and SM species bearing ALA at their sn-2 position, were identified in the SM subclass, providing a rational for its strong bioactivities against the PAF pathway. Further studies are required on the health benefits of bioactive PL from beer and brewery by-products.

Inflammation and cardiovascular disease: are marine phospholipids the answer?

This review presents the latest research on the cardioprotective effects of n-3 fatty acids (FA) and n-3 FA bound to polar lipids (PL). Overall, n-3 PL may have enhanced bioavailability and potentially bioactivityversusfree FA and ester forms of n-3 FA.

The Potential Role of Dietary Platelet-Activating Factor Inhibitors in Cancer Prevention and Treatment

Cancer is the second leading cause of mortality worldwide. The role of unresolved inflammation in cancer progression and metastasis is well established. Platelet-activating factor (PAF) is a key proinflammatory mediator in the initiation and progression of cancer. Evidence suggests that PAF is integral to suppression of the immune system and promotion of metastasis and tumor growth by altering local angiogenic and cytokine networks. Interactions between PAF and its receptor may have a role in various digestive, skin, and hormone-dependent cancers. Diet plays a critical role in the prevention of cancer and its treatment. Research indicates that the Mediterranean diet may reduce the incidence of several cancers in which dietary PAF inhibitors have a role. Dietary PAF inhibitors such as polar lipids have demonstrated inhibitory effects against the physiological actions of PAF in cancer and other chronic inflammatory conditions in vitro and in vivo. In addition, experimental models of radiotherapy and chemotherapy demonstrate that inhibition of PAF as adjuvant therapy may lead to more favorable outcomes. Although promising, there is limited evidence on the potential benefits of dietary PAF inhibitors on cancer prevention or treatment. Therefore, further extensive research is required to assess the effects of various dietary factors and PAF inhibitors and to elucidate the mechanisms in prevention of cancer progression and metastasis at a molecular level.