Multiple Pathways Involved in Palmitic Acid-Induced Toxicity: A System Biology Approach

The differential effects of palmitic acid and oleic acid on the metabolic response of hypothalamic astrocytes from male and female mice

Diets rich in saturated fats are more detrimental to health than those containing mono- or unsaturated fats. Fatty acids are an important source of energy, but they also relay information regarding nutritional status to hypothalamic metabolic circuits and when in excess can be detrimental to these circuits. Astrocytes are the main site of central fatty acid β-oxidation, and hypothalamic astrocytes participate in energy homeostasis, in part by modulating hormonal and nutritional signals reaching metabolic neurons, as well as in the inflammatory response to high-fat diets. Thus, we hypothesized that how hypothalamic astrocytes process-specific fatty acids participates in determining the differential metabolic response and that this is sex dependent as males and females respond differently to high-fat diets. Male and female primary hypothalamic astrocyte cultures were treated with oleic acid (OA) or palmitic acid (PA) for 24 h, and an untargeted metabolomics study was performed. A clear predictive model for PA exposure was obtained, while the metabolome after OA exposure was not different from controls. The observed modifications in metabolites, as well as the expression levels of key metabolic enzymes, indicate a reduction in the activity of the Krebs and glutamate/glutamine cycles in response to PA. In addition, there were specific differences between the response of astrocytes from male and female mice, as well as between hypothalamic and cerebral cortical astrocytes. Thus, the response of hypothalamic astrocytes to specific fatty acids could result in differential impacts on surrounding metabolic neurons and resulting in varied systemic metabolic outcomes.

Gut-brain communication mediates the impact of dietary lipids on cognitive capacity

Cognitive impairment, as a prevalent symptom of nervous system disorders, poses one of the most challenging aspects in the management of brain diseases. Lipids present in the cell membranes of all neurons within the brain and dietary lipids can regulate the cognition and memory function. In recent years, the advancements in gut microbiome research have enabled the exploration of dietary lipids targeting the gut-brain axis as a strategy for regulating cognition. This present review provides an in-depth overview of how lipids modulate cognition via the gut-brain axis depending on metabolic, immune, neural and endocrine pathways. It also comprehensively analyzes the effects of diverse lipids on the gut microbiota and intestinal barrier function, thereby affecting the central nervous system and cognitive capacity. Moreover, comparative analysis of the positive and negative effects is presented between beneficial and detrimental lipids. The former encompass monounsaturated fatty acids, short-chain fatty acids, omega-3 polyunsaturated fatty acids, phospholipids, phytosterols, fungal sterols and bioactive lipid-soluble vitamins, as well as lipid-derived gut metabolites, whereas the latter (detrimental lipids) include medium- or long-chain fatty acids, excessive proportions of n-6 polyunsaturated fatty acids, industrial trans fatty acids, and zoosterols. To sum up, the focus of this review is on how gut-brain communication mediates the impact of dietary lipids on cognitive capacity, providing a novel theoretical foundation for promoting brain cognitive health and scientific lipid consumption patterns.

Saturated and unsaturated triglyceride-enriched diets modify amino acid content in the mice hippocampus

Elevated intake of fat modulates l-glutamate (l-Glu) turnover within the hippocampus (HIP). Our aim has been to investigate the effect of saturated vs unsaturated fat on the content of l-Glu and other amino acids involved in synaptic transmission within the HIP. The study was carried out in male mice fed (2 h or 8 weeks) with standard chow or with diets enriched either with saturated (SOLF) or unsaturated triglycerides (UOLF). An in vitro assay was performed in HIP slices incubated with palmitic (PA), oleic (OA), or lauric acid (LA). Amino acids were quantified by capillary electrophoresis. While both diets increased the amount of l-Glu and l-aspartate and decreased l-glutamine levels, only UOLF affected d-serine and taurine levels. γ-Aminobutyric acid was specifically decreased by SOLF. In vitro assays revealed that PA and OA modified l-Glu, glycine, l-serine and d-serine concentration. Our results suggest that fatty acids contained in SOLF and UOLF have an impact on HIP amino acid turnover that may account, at least partially, for the functional changes evoked by these diets.

The Role of Dietary Lipids in Cognitive Health: Implications for Neurodegenerative Disease

Neurodegenerative diseases are a group of disorders characterised by progressive loss of brain function. The most common of these is Alzheimer's disease, a form of dementia. Intake of macro- and micro-nutrients impacts brain function, including memory, learning, mood, and behaviour. Lipids, particularly phospholipids and sphingolipids, are crucial structural components of neural tissues and significantly affect cognitive function. The importance of functional foods in preventing cardiovascular disease is well-documented in the current literature. However, the significance of such foods for central nervous system health and neurodegenerative diseases is less recognized. Gut microbiome composition affects cognitive health and function, and dietary lipids are known to influence gut health. Thus, this review will discuss different sources of dietary lipids and their effect on cognitive functioning and their interaction with the gut microbiome in the context of neurodegenerative disease.

In Vitro and In Silico Evaluations of Boswellia carterii Resin Dermocosmetic Activities

Boswellia carterii is a plant species belonging to the Burseraceae family. It grows up in trees or shrubs, and it is known for producing an aromatic resin commonly named frankincense or olibanum. This resin has been used in traditional medicine to treat various conditions such as inflammations, gastrointestinal disorders and traumatic injuries. Virtual screening and molecular docking are two in silico approaches used to predict potential interactions between ligands and the active site of a protein. These approaches are mainly used in natural product chemistry and pharmacology as a screening tool to select plant extracts or fractions for in vitro testing, as well as for the prediction of mechanisms of action. The aim of this research is the in silico and in vitro evaluations of the potential collagenase and elastase inhibitory activities of Boswellia carterii resin organic extracts (viz., methanol, n-hexane and ethyl acetate). The obtained results revealed that methanol and n-hexane exhibited the best collagenase inhibitory activity with values superior to 85%, whereas the methanol and ethyl acetate showed the highest elastase inhibition activity with inhibition values ranging between 40 and 60%. The molecular docking prediction confirmed the experimental results; moreover, the visualization of the ligand–protein interactions showed that the main compounds of the organic extracts may have mechanisms of action similar to the positive controls. Those findings are very promising and open new perspectives for the exploitation of Boswellia carterii resin as active agents for the development of anti-aging cosmeceuticals.

Metabolomic Analysis of Human Astrocytes in Lipotoxic Condition: Potential Biomarker Identification by Machine Learning Modeling

The association between neurodegenerative diseases (NDs) and obesity has been well studied in recent years. Obesity is a syndrome of multifactorial etiology characterized by an excessive accumulation and release of fatty acids (FA) in adipose and non-adipose tissue. An excess of FA generates a metabolic condition known as lipotoxicity, which triggers pathological cellular and molecular responses, causing dysregulation of homeostasis and a decrease in cell viability. This condition is a hallmark of NDs, and astrocytes are particularly sensitive to it, given their crucial role in energy production and oxidative stress management in the brain. However, analyzing cellular mechanisms associated with these conditions represents a challenge. In this regard, metabolomics is an approach that allows biochemical analysis from the comprehensive perspective of cell physiology. This technique allows cellular metabolic profiles to be determined in different biological contexts, such as those of NDs and specific metabolic insults, including lipotoxicity. Since data provided by metabolomics can be complex and difficult to interpret, alternative data analysis techniques such as machine learning (ML) have grown exponentially in areas related to omics data. Here, we developed an ML model yielding a 93% area under the receiving operating characteristic (ROC) curve, with sensibility and specificity values of 80% and 93%, respectively. This study aimed to analyze the metabolomic profiles of human astrocytes under lipotoxic conditions to provide powerful insights, such as potential biomarkers for scenarios of lipotoxicity induced by palmitic acid (PA). In this work, we propose that dysregulation in seleno-amino acid metabolism, urea cycle, and glutamate metabolism pathways are major triggers in astrocyte lipotoxic scenarios, while increased metabolites such as alanine, adenosine, and glutamate are suggested as potential biomarkers, which, to our knowledge, have not been identified in human astrocytes and are proposed as candidates for further research and validation.

Plin5, a New Target in Diabetic Cardiomyopathy

Abnormal lipid accumulation is commonly observed in diabetic cardiomyopathy (DC), which can create a lipotoxic microenvironment and damage cardiomyocytes. Lipid toxicity is an important pathogenic factor due to abnormal lipid accumulation in DC. As a lipid droplet (LD) decomposition barrier, Plin5 can protect LDs from lipase decomposition and regulate lipid metabolism, which is involved in the occurrence and development of cardiovascular diseases. In recent years, studies have shown that Plin5 expression is involved in the pathogenesis of DC lipid toxicity, such as oxidative stress, mitochondrial dysfunction, endoplasmic reticulum (ER) stress, and insulin resistance (IR) and has become a key target of DC research. Therefore, understanding the relationship between Plin5 and DC progression as well as the mechanism of this process is crucial for developing new therapeutic approaches and exploring new therapeutic targets. This review is aimed at exploring the latest findings and roles of Plin5 in lipid metabolism and DC-related pathogenesis, to explore possible clinical intervention approaches.

Palmitic Acid Lipotoxicity in Microglia Cells Is Ameliorated by Unsaturated Fatty Acids

Obesity and metabolic syndrome are associated with cognitive decline and dementia. Palmitic acid (PA) is increased in the cerebrospinal fluid of obese patients with cognitive impairment. This study was therefore designed to examine fatty acid (FA) lipotoxicity in BV2 microglia cells. We found that PA induced time- and dose-dependent decrease in cell viability and increase in cell death without affecting the cell cycle profile and that PA lipotoxicity did not depend on cell surface free fatty acid receptors but rather on FA uptake. Treatment with sulfosuccinimidyl oleate (SSO), an irreversible inhibitor of fatty acid translocase CD36, significantly inhibited FA uptake in BSA- and PA-treated cells and blocked PA-induced decrease in cell viability. Inhibition of ER stress or treatment with N-acetylcysteine was not able to rescue PA lipotoxicity. Our study also showed that unsaturated fatty acids (UFAs), such as linoleic acid (LA), oleic acid (OA), α-linolenic acid (ALA), and docosahexaenoic acid (DHA), were not lipotoxic but instead protected microglia against PA-induced decrease in cell viability. Co-treatment of PA with LA, OA, and DHA significantly inhibited FA uptake in PA-treated cells. All UFAs tested induced the incorporation of FAs into and the amount of neutral lipids, while PA did not significantly affect the amount of neutral lipids compared with BSA control.

Network pharmacology identifies IL6 as an important hub and target of tibolone for drug repurposing in traumatic brain injury

Traumatic brain injury (TBI) is characterized by a complex network of signals mediating inflammatory, proliferative and apoptotic processes during its acute and chronic phases. Current therapies mitigate damage and are mainly for palliative care and there are currently no effective therapies for secondary damage. This suggests a need to discover a compound with a greater spectrum of action that can control various pathological aspects of TBI. Here we used a network pharmacology approach to explore the benefits of tibolone, an estrogen and androgen receptor agonist with broader actions in cells, as a possible repurposing drug for TBI therapy. Using different databases we retrieved the targets significantly associated to TBI and tibolone, obtaining 2700 and 652, respectively. The top 10 GO enriched terms were mostly related to cell proliferation, apoptosis and inflammation. Following protein-protein functional analysis, the top connected proteins were related to kinase activity (MAPK1/14/3, AKT1 PIK3R1), apoptosis (TP53, CASP3), growth factors (EGFR), estrogen signalling (ESR1) and inflammation (IL6, TNF), with IL6 as an important signalling hub belonging to the top GO categories. Thus, we identified IL6 as a cellular node which we then validated using molecular mechanics-generalized born surface area (MMGBSA) and docking to explore which tibolone metabolite might interact with this protein. Both 3α and 3β-OH tibolone seemed to bind better to IL6 at important sites responsible for its binding to IL6R. In conclusion, our study demonstrates key hubs involved in TBI pathology which indicates IL6 as a target molecule of tibolone as drug repurposing for TBI therapy.

Estrogenic Plants: to Prevent Neurodegeneration and Memory Loss and Other Symptoms in Women After Menopause

In mammals, sexual hormones such as estrogens play an essential role in maintaining brain homeostasis and function. Estrogen deficit in the brain induces many undesirable symptoms such as learning and memory impairment, sleep and mood disorders, hot flushes, and fatigue. These symptoms are frequent in women who reached menopausal age or have had ovariectomy and in men and women subjected to anti-estrogen therapy. Hormone replacement therapy alleviates menopause symptoms; however, it can increase cardiovascular and cancer diseases. In the search for therapeutic alternatives, medicinal plants and specific synthetic and natural molecules with estrogenic effects have attracted widespread attention between the public and the scientific community. Various plants have been used for centuries to alleviate menstrual and menopause symptoms, such as Cranberry, Ginger, Hops, Milk Thistle, Red clover, Salvia officinalis, Soy, Black cohosh, Turnera diffusa, Ushuva, and Vitex. This review aims to highlight current evidence about estrogenic medicinal plants and their pharmacological effects on cognitive deficits induced by estrogen deficiency during menopause and aging.

Advances in Astrocyte Computational Models: From Metabolic Reconstructions to Multi-omic Approaches

The growing importance of astrocytes in the field of neuroscience has led to a greater number of computational models devoted to the study of astrocytic functions and their metabolic interactions with neurons. The modeling of these interactions demands a combined understanding of brain physiology and the development of computational frameworks based on genomic-scale reconstructions, system biology, and dynamic models. These computational approaches have helped to highlight the neuroprotective mechanisms triggered by astrocytes and other glial cells, both under normal conditions and during neurodegenerative processes. In the present review, we evaluate some of the most relevant models of astrocyte metabolism, including genome-scale reconstructions and astrocyte-neuron interactions developed in the last few years. Additionally, we discuss novel strategies from the multi-omics perspective and computational models of other glial cell types that will increase our knowledge in brain metabolism and its association with neurodegenerative diseases.

Lipid metabolism in astrocytic structure and function

Astrocytes are the most abundant glial cell in the central nervous system and are involved in multiple processes including metabolic homeostasis, blood brain barrier regulation and neuronal crosstalk. Astrocytes are the main storage point of glycogen in the brain and it is well established that astrocyte uptake of glutamate and release of lactate prevents neuronal excitability and supports neuronal metabolic function. However, the role of lipid metabolism in astrocytes in relation to neuronal support has been until recently, unclear. Lipids play a fundamental role in astrocyte function, including energy generation, membrane fluidity and cell to cell signaling. There is now emerging evidence that astrocyte storage of lipids in droplets has a crucial physiological and protective role in the central nervous system. This pathway links β-oxidation in astrocytes to inflammation, signalling, oxidative stress and mitochondrial energy generation in neurons. Disruption in lipid metabolism, structure and signalling in astrocytes can lead to pathogenic mechanisms associated with a range of neurological disorders.