Palmitoylethanolamide Promotes a Proresolving Macrophage Phenotype and Attenuates Atherosclerotic Plaque Formation

Interaction between lipid metabolism and macrophage polarization in atherosclerosis

Atherosclerosis (AS) is a chronic inflammatory condition associated with lipid deposition. The interaction between abnormal lipid metabolism and the inflammatory response has been identified as the underlying cause of AS. Lipid metabolism disorders are considered the basis of atherosclerotic lesion formation and macrophages are involved in the entire process of AS formation. Macrophages have a high degree of plasticity, and the change of their polarization direction can determine the progress or regression of AS. The disturbances in bioactive lipid metabolism affect the polarization of different phenotypes of macrophages, thus, affecting lipid metabolism and the expression of key signal factors. Therefore, understanding the interaction between lipid metabolism and macrophages as well as their key targets is important for preventing and treating AS and developing new drugs. Recent studies have shown that traditional Chinese medicines play a positive role in the prevention and treatment of AS, providing a basis for clinical individualized treatment.

PLAAT5 as an N-acyltransferase responsible for the generation of anti-inflammatory N-acylethanolamines in testis

N-Acylethanolamines (NAEs) are a class of lipid mediators that exhibit anti-inflammatory and appetite-suppressive activities. Among them, palmitoylethanolamide (PEA) and arachidonoylethanolamide (AEA) bind to peroxisomal proliferator-activated receptor (PPAR) α and cannabinoid receptor CB1, respectively. N-Acyl-phosphatidylethanolamine (NAPE) as a precursor of NAEs is biosynthesized from membrane phospholipids by N-acyltransferases, which consist of group IVE cytosolic phospholipase A2ε (cPLA2ε) and PLAAT (phospholipase A and acyltransferase) family enzymes. While cPLA2ε is responsible for the production of NAEs not only in specific tissues, including muscle, skin, and the stomach, but also under pathological conditions, such as psoriasis and brain ischemia, the involvement of the PLAAT family in vivo remains unclear. Considering the specific expression of PLAAT5 in testes, we investigated the potential role of PLAAT5 in the formation of NAEs in testes using PLAAT5-deficient (Plaat5-/-) mice. High-performance liquid chromatography coupled with tandem mass spectrometry showed that PLAAT5 deficiency decreased the total level of NAEs by 61 %, with PEA and AEA being reduced by 64 % and 87 %, respectively. Following a treatment with cadmium chloride, an environmental toxin that induces testicular inflammation, the expression of inflammatory genes (Il6, Tnf, and Nos2) in testes was markedly higher in Plaat5-/- mice than in Plaat5+/+ mice, and their expression was attenuated by the administration of PEA and AEA. Furthermore, these anti-inflammatory effects were canceled by a co-treatment with the antagonists of PPARα or CB1. These results suggest that PLAAT5 is responsible for the biosynthesis of anti-inflammatory NAEs in testes.

Oleoylethanolamide mitigates cardiometabolic disruption secondary to obesity induced by high-fat diet in mice

Chronic lipid overnutrition has been demonstrated to promote cardiac dysfunction resulting from metabolic derangement, inflammation, and fibrosis. Oleoylethanolamide (OEA), an endogenous peroxisome proliferator activating receptor (PPAR)-α agonist, has been extensively studied for its metabolic properties. The aim of this study was to determine if OEA has beneficial effects on high-fat diet (HFD)-induced cardiac disruption in obese mice, focusing on the underlying pathological mechanisms. OEA treatment restores the metabolic pattern, improving serum glycaemic and lipid profile. OEA also reduces heart weight and serum creatine kinase-myocardial band (CK-MB), a marker of cardiac damage. Accordingly, OEA modulates cardiac metabolism, increasing insulin signaling and reducing lipid accumulation. OEA increases AMPK and AKT phosphorylation, converging in the rise of AS160 activation and glucose transporter (GLUT)4 protein level. Moreover, OEA reduces the transcription of the cardiac fatty acid transporter CD36 and fatty acid synthase and increases PPAR-α mRNA levels. Adiponectin and meteorite-like protein transcription levels were significantly reduced by OEA in HFD mice, as well as those of inflammatory cytokines and pro-fibrotic markers. An increased autophagic process was also shown, contributing to OEA's cardioprotective effects. Metabolomic analyses of cardiac tissue revealed the modulation of different lipids, including triglycerides, glycerophospholipids and sphingomyelins by OEA treatment. In vitro experiments on HL-1 cardiomyocytes showed OEA's capability in reducing inflammation and fibrosis following palmitate challenge, demonstrating a direct activity of OEA on cardiac cells, mainly mediated by PPAR-α activation. Our results indicate OEA as a potential therapeutic to restrain cardiac damage associated with metabolic disorders.

Defective macrophage efferocytosis in advanced atherosclerotic plaque and mitochondrial therapy

Atherosclerosis (AS) is a chronic inflammatory disease primarily affecting large and medium-sized arterial vessels, characterized by lipoprotein disorders, intimal thickening, smooth muscle cell proliferation, and the formation of vulnerable plaques. Macrophages (MΦs) play a vital role in the inflammatory response throughout all stages of atherosclerotic development and are considered significant therapeutic targets. In early lesions, macrophage efferocytosis rapidly eliminates harmful cells. However, impaired efferocytosis in advanced plaques perpetuates the inflammatory microenvironment of AS. Defective efferocytosis has emerged as a key factor in atherosclerotic pathogenesis and the progression to severe cardiovascular disease. Herein, this review probes into investigate the potential mechanisms at the cellular, molecular, and organelle levels underlying defective macrophage efferocytosis in advanced lesion plaques. In the inflammatory microenvironments of AS with interactions among diverse inflammatory immune cells, impaired macrophage efferocytosis is strongly linked to multiple factors, such as a lower absolute number of phagocytes, the aberrant expression of crucial molecules, and impaired mitochondrial energy provision in phagocytes. Thus, focusing on molecular targets to enhance macrophage efferocytosis or targeting mitochondrial therapy to restore macrophage metabolism homeostasis has emerged as a potential strategy to mitigate the progression of advanced atherosclerotic plaque, providing various treatment options.

N-Aldehyde-Modified Phosphatidylethanolamines generated by lipid peroxidation are robust substrates of N-Acyl Phosphatidylethanolamine Phospholipase D

N-acyl phosphatidylethanolamine-hydrolyzing phospholipase D (NAPE-PLD) hydrolyzes phosphatidylethanolamines (PE) where the headgroup nitrogen has been enzymatically modified with acyl chains of four carbons or longer (N-acyl-PEs or NAPEs). The nitrogen headgroup of PE can also be non-enzymatically modified by reactive lipid aldehydes, thus forming N-aldehyde modified-PEs (NALPEs). Some NALPEs such as N-carboxyacyl-PEs are linked to PE via amide bonds similar to NAPEs, but others are linked by imine, pyrrole, or lactam moieties. Whether NAPE-PLD can hydrolyze NALPEs was unknown. We therefore characterized the major NALPE species formed during lipid peroxidation of arachidonic acid and linoleic acid and generated various NALPEs for characterization of their sensitivity to NAPE-PLD hydrolysis by reacting synthesized aldehydes with PE. We found that NAPE-PLD could act on NALPEs of various lengths and linkage types including those derived from PE modified by malondialdehyde (N-MDA-PE), butane dialdehyde (N-BDA-PE), 4-hydroxynonenal (N-HNE-PE), 4-oxo-nonenal (N-ONE-PE), 9-keto-12-oxo-dodecenoic acid (N-KODA-PE), and 15-E2-isolevuglandin (N-IsoLG-PE). To assess the relative preference of NAPE-PLD for various NALPEs versus its canonical NAPE substrates, we generated a substrate mixture containing roughly equimolar concentrations of the seven NALPEs as well as two NAPEs (N-palmitoyl-PE and N-linoleoyl-PE) and measured their rate of hydrolysis. Several NALPE species, including the N-HNE-PE pyrrole species, were hydrolyzed at a similar rate as N-linoleoyl-PE and many of the other NALPEs showed intermediate rates of hydrolysis. These results significantly expand the substrate repertoire of NAPE-PLD and suggest that it may play an important role in clearing products of lipid peroxidation in addition to its established role in the biosynthesis of N-acyl-ethanolamines.

New insights in the mechanisms of opioid analgesia and tolerance: Ultramicronized palmitoylethanolamide down-modulates vascular endothelial growth factor-A in the nervous system

Growing evidence suggests that opioid analgesics modulate angiogenesis during pathophysiological processes. Vascular endothelial growth factor-A (VEGF-A) was recently proposed to be involved in pain development. To date, no anti-angiogenic drug is used for pain management. When administered in a bioavailable formulation, (i.e., ultramicronized) N-palmitoylethanolamine (PEA) delays the onset of morphine tolerance, improves morphine analgesic activity and reduces angiogenesis in in vivo models. This study aimed at investigating whether VEGF-A is involved in PEA-induced delay of morphine tolerance. The anti-VEGF-A monoclonal antibody bevacizumab was used as a reference drug. Preemptive and concomitant treatment with ultramicronized PEA delayed morphine tolerance and potentiated the analgesic effect of morphine, while counteracting morphine-induced increase of VEGF-A in the nervous system. Similar results were obtained when bevacizumab was administered together with morphine. Of note, bevacizumab showed an analgesic effect per se. In equianalgesic treatment regimens (obtained through increasing morphine doses and associating PEA), PEA resulted in lower expression of VEGF-A in dorsal root ganglia (DRG) and spinal cord compared to morphine alone. Similar results were observed for plasma levels of the soluble VEGF receptor 1 (sFLT-1). Moreover, in morphine-treated animals, two pain-related genes (i.e., Serpina3n and Eaat2) showed a more than 3-fold increase in their expression at spinal cord and DRG level, with the increase being significantly counteracted by PEA treatment. This study supports the hypothesis that the effects of PEA on morphine analgesia and tolerance may be mediated by the down-modulation of VEGF-A and sFLT-1 in the nervous system and plasma, respectively.

Plaat1l1 controls feeding induced NAPE biosynthesis and contributes to energy balance regulation in zebrafish

Dysregulation of energy balance leading to obesity is a significant risk factor for cardiometabolic diseases such as diabetes, non-alcoholic fatty liver disease and atherosclerosis. In rodents and several other vertebrates, feeding has been shown to induce a rapid rise in the intestinal levels of N-acyl-ethanolamines (NAEs) and the chronic consumption of a high fat diet abolishes this rise. Administering NAEs to rodents consuming a high fat diet reduces their adiposity, in part by reducing food intake and enhancing fat oxidation, so that feeding-induced intestinal NAE biosynthesis appears to be critical to appropriate regulation of energy balance. However, the contribution of feeding-induced intestinal NAE biosynthesis to appropriate energy balance remains poorly understood in part because there are multiple enzymes that can contribute to NAE biosynthesis and the specific enzyme(s) that are responsible for feeding-induced intestinal NAE biosynthesis have not been identified. The rate-limiting step in the intestinal biosynthesis of NAEs is formation of their immediate precursors, the N-acyl-phosphatidylethanolamines (NAPEs), by phosphatidylethanolamine N-acyltransferases (NATs). At least six NATs are found in humans and multiple homologs of these NATs are found in most vertebrate species. In recent years, the fecundity and small size of zebrafish (Danio rerio), as well as their similarities in feeding behavior and energy balance regulation with mammals, have led to their use to model key features of cardiometabolic disease. We therefore searched the Danio rerio genome to identify all NAT homologs and found two additional NAT homologs besides the previously reported plaat1, rarres3, and rarres3l, and used CRISPR/cas9 to delete these two NAT homologs (plaat1l1 and plaat1l2). While wild-type fish markedly increased their intestinal NAPE levels in response to a meal after fasting, this response was completely ablated in plaat1l1-/-fish. Furthermore, plaat1l1-/- fish fed a standard flake diet had increased weight gain and glucose intolerance compared to wild-type fish. The results support a critical role for feeding-induced NAPE and NAE biosynthesis in regulating energy balance and suggest that restoring this response in obese animals could potentially be used to treat obesity and cardiometabolic disease.

Plasma endocannabinoidome and fecal microbiota interplay in people with HIV and subclinical coronary artery disease: Results from the Canadian HIV and Aging Cohort Study

Chronic HIV infection is associated with accelerated coronary artery disease (CAD) due to chronic inflammation. The expanded endocannabinoid system (eCBome) and gut microbiota modulate each other and are key regulators of cardiovascular functions and inflammation. We herein investigated the interplay between plasma eCBome mediators and gut microbiota in people with HIV (PWH) and/or subclinical CAD versus HIV-uninfected individuals. CAD was determined by coronary computed tomography (CT) angiography performed on all participants. Plasma eCBome mediator and fecal microbiota composition were assessed by tandem mass spectrometry and 16S rDNA sequencing, respectively. HIV infection was associated with perturbed plasma eCBome mediators characterized by an inverse relationship between anandamide and N-acyl-ethanolamines (NAEs) versus 2-AG and 2-monoacylglycerols (MAGs). Plasma triglyceride levels were positively associated with MAGs. Several fecal bacterial taxa were altered in HIV-CAD+ versus controls and correlated with plasma eCBome mediators. CAD-associated taxonomic alterations in fecal bacterial taxa were not found in PWH.

Ultramicronized N-palmitoylethanolamine associated with analgesics: Effects against persistent pain

Current epidemiological data estimate that one in five people suffers from chronic pain with considerable impairment of health-related quality of life. The pharmacological treatment is based on first- and second-line analgesic drugs, including COX-2 selective and nonselective nonsteroidal anti-inflammatory drugs, paracetamol, antidepressants, anti-seizure drugs and opioids, that are characterized by important side effects. N-palmitoylethanolamine (PEA) is a body's own fatty-acid ethanolamide belonging to the family of autacoid local injury antagonist amides. The anti-inflammatory and pain-relieving properties of PEA have been recognized for decades and prompted to depict its role in the endogenous mechanisms of pain control. Together with its relative abundance in food sources, this opened the way to the use of PEA as a pain-relieving nutritional intervention. Naïve PEA is a large particle size lipid molecule with low solubility and bioavailability. Reducing particle size is a useful method to increase surface area, thereby improving dissolution rate and bioavailability accordingly. Micron-size formulations of PEA (e.g., ultramicronized and co-(ultra)micronized) have shown higher oral efficacy compared to naïve PEA. In particular, ultramicronized PEA has been shown to efficiently cross the intestinal wall and, more importantly, the blood-brain and blood-spinal cord barrier. Several preclinical and clinical studies have shown the efficacy, safety and tolerability of ultramicronized PEA. This narrative review summarizes the available pharmacokinetic/pharmacodynamic data on ultramicronized PEA and focuses to its contribution to pain control, in particular as 'add-on' nutritional intervention. Data showing the ability of ultramicronized PEA to limit opioid side effects, including the development of tolerance, have also been reviewed.

Targeted proteomics and metabolomics for biomarker discovery in abdominal aortic aneurysm and post-EVAR sac volume

BACKGROUND AND AIMS

Abdominal aortic aneurysm (AAA) patients undergo uniform surveillance programs both leading up to, and following surgery. Circulating biomarkers could play a pivotal role in individualizing surveillance. We applied a multi-omics approach to identify relevant biomarkers and gain pathophysiological insights.

MATERIALS AND METHODS

In this cross-sectional study, 108 AAA patients and 200 post-endovascular aneurysm repair (post-EVAR) patients were separately investigated. We performed partial least squares regression and ingenuity pathway analysis on circulating concentrations of 96 proteins (92 Olink Cardiovascular-III panel, 4 ELISA-assays) and 199 metabolites (measured by LC-TQMS), and their associations with CT-based AAA/sac volume.

RESULTS

The median (25th-75th percentile) maximal diameter was 50.0 mm (46.0, 53.0) in the AAA group, and 55.4 mm (45.0, 64.2) in the post-EVAR group. Correcting for clinical characteristics in AAA patients, the aneurysm volume Z-score differed 0.068 (95 %CI: (0.042, 0.093)), 0.066 (0.047, 0.085) and -0.051 (-0.064, -0.038) per Z-score valine, leucine and uPA, respectively. After correcting for clinical characteristics and orthogonalization in the post-EVAR group, the sac volume Z-score differed 0.049 (0.034, 0.063) per Z-score TIMP-4, -0.050 (-0.064, -0.037) per Z-score LDL-receptor, -0.051 (-0.062, -0.040) per Z-score 1-OG/2-OG and -0.056 (-0.066, -0.045) per Z-score 1-LG/2-LG.

CONCLUSIONS

The branched-chain amino acids and uPA were related to AAA volume. For post-EVAR patients, LDL-receptor, monoacylglycerols and TIMP-4 are potential biomarkers for sac volume. Additionally, distinct markers for sac change were identified.

The role of efferocytosis-fueled macrophage metabolism in the resolution of inflammation

The phagocytosis of dying cells by macrophages, termed efferocytosis, is a tightly regulated process that involves the sensing, binding, engulfment, and digestion of apoptotic cells. Efferocytosis not only prevents tissue necrosis and inflammation caused by secondary necrosis of dying cells, but it also promotes pro-resolving signaling in macrophages, which is essential for tissue resolution and repair following injury or inflammation. An important factor that contributes to this pro-resolving reprogramming is the cargo that is released from apoptotic cells after their engulfment and phagolysosomal digestion by macrophages. The apoptotic cell cargo contains amino acids, nucleotides, fatty acids, and cholesterol that function as metabolites and signaling molecules to bring about this re-programming. Here, we review efferocytosis-induced changes in macrophage metabolism that mediate the pro-resolving functions of macrophages. We also discuss various strategies, challenges, and future perspectives related to drugging efferocytosis-fueled macrophage metabolism as strategy to dampen inflammation and promote resolution in chronic inflammatory diseases.

Small Molecule Activation of NAPE-PLD Enhances Efferocytosis by Macrophages

N-Acyl-phosphatidylethanolamine hydrolyzing phospholipase D (NAPE-PLD) is a zinc metallohydrolase that hydrolyzes N-acyl-phosphatidylethanolamines (NAPEs) to form N-acyl-ethanolamines (NAEs) and phosphatidic acid. Several lines of evidence suggest that reduced NAPE-PLD activity could contribute to cardiometabolic diseases. For instance, NAPEPLD expression is reduced in human coronary arteries with unstable atherosclerotic lesions, defective efferocytosis is implicated in the enlargement of necrotic cores of these lesions, and NAPE-PLD products such as palmitoylethanolamide and oleoylethanolamide have been shown to enhance efferocytosis. Thus, enzyme activation mediated by a small molecule may serve as a therapeutic treatment for cardiometabolic diseases. As a proof-of-concept study, we sought to identify small molecule activators of NAPE-PLD. High-throughput screening followed by hit validation and primary lead optimization studies identified a series of benzothiazole phenylsulfonyl-piperidine carboxamides that variably increased activity of both mouse and human NAPE-PLD. From this set of small molecules, two NAPE-PLD activators (VU534 and VU533) were shown to increase efferocytosis by bone-marrow derived macrophages isolated from wild-type mice, while efferocytosis was significantly reduced in Napepld-/- BMDM or after Nape-pld inhibition. Together, these studies demonstrate an essential role for NAPE-PLD in the regulation of efferocytosis and the potential value of NAPE-PLD activators as a strategy to treat cardiometabolic diseases.

Lysophosphatidylglucoside/GPR55 signaling promotes foam cell formation in human M2c macrophages

Atherosclerosis is a major cause of cerebral and cardiovascular diseases. Intravascular plaques, a well-known pathological finding of atherosclerosis, have a necrotic core composed of macrophages and dead cells. Intraplaque macrophages, which are classified into various subtypes, play key roles in maintenance of normal cellular microenvironment. Excessive uptake of oxidized low-density lipoprotein causes conversion of macrophages to foam cells, and consequent progression/exacerbation of atherosclerosis. G-protein-coupled receptor 55 (GPR55) signaling has been reported to associate with atherosclerosis progression. We demonstrated recently that lysophosphatidylglucoside (lysoPtdGlc) is a specific ligand of GPR55, although in general physiological ligands of GPR55 are poorly understood. Phosphatidylglucoside is expressed on human monocytes and can be converted to lysoPtdGlc. In the present study, we examined possible involvement of lysoPtdGlc/GPR55 signaling in foam cell formation. In monocyte-derived M2c macrophages, lysoPtdGlc/GPR55 signaling inhibited translocation of ATP binding cassette subfamily A member 1 to plasma membrane, and cholesterol efflux. Such inhibitory effect was reversed by GPR55 antagonist ML193. LysoPtdGlc/GPR55 signaling in M2c macrophages was involved in excessive lipid accumulation, thereby promoting foam cell formation. Our findings suggest that lysoPtdGlc/GPR55 signaling is a potential therapeutic target for inhibition of atherosclerosis progression.

Target and Cell Therapy for Atherosclerosis and CVD

Cardiovascular diseases (CVD) and, in particular, atherosclerosis, remain the main cause of death in the world today. Unfortunately, in most cases, CVD therapy begins after the onset of clinical symptoms and is aimed at eliminating them. In this regard, early pathogenetic therapy for CVD remains an urgent problem in modern science and healthcare. Cell therapy, aimed at eliminating tissue damage underlying the pathogenesis of some pathologies, including CVD, by replacing it with various cells, is of the greatest interest. Currently, cell therapy is the most actively developed and potentially the most effective treatment strategy for CVD associated with atherosclerosis. However, this type of therapy has some limitations. In this review, we have tried to summarize the main targets of cell therapy for CVD and atherosclerosis in particular based on the analysis using the PubMed and Scopus databases up to May 2023.

The phagocytic role of macrophage following myocardial infarction

Myocardial infarction (MI) is one of the cardiovascular diseases with high morbidity and mortality. MI causes large amounts of apoptotic and necrotic cells that need to be efficiently and instantly engulfed by macrophage to avoid second necrosis. Phagocytic macrophages can dampen or resolve inflammation to protect infarcted heart. Phagocytosis of macrophages is modulated by various factors including proteins, receptors, lncRNA and cytokines. A better understanding of mechanisms in phagocytosis will be beneficial to regulate macrophage phagocytosis capability towards a desired direction in cardioprotection after MI. In this review, we describe the phagocytosis effect of macrophages and summarize the latest reported signals regulating phagocytosis after MI, which will provide a new thinking about phagocytosis-dependent cardiac protection after MI.

Cannabinoids And Cannabinoid-Like Compounds: Biochemical Characterization And Pharmacological Perspectives

Publication interest in cannabinoids, including phytocannabinoids, endogenous cannabinoids, synthetic cannabinoids and cannabinomimetic compounds, is due to the therapeutic potential of these compounds in inflammatory pathology. Since recent years, scientific interest was focused on compounds with cannabinomimetic activity. The therapeutic use of phytocannabinoids and endocannabinoids is somewhat limited due to unresolved issues of dosing, toxicity and safety in humans, while cannabinoid-like compounds combine similar therapeutic effects with a high confirmed safety. Targets for endocannabinoids and phytocannabinoids are endocannabinoid receptors 1 and 2, G protein-coupled receptors (GPCRs), peroxisome proliferator-activated receptors (PPARs), and transient receptor potential ion channels (TRPs). Non-endocannabinoid N-acylethanolamines do not interact with cannabinoid receptors and exhibit agonist activity towards non-cannabinoid receptors, such as PPARs, GPCRs and TRPs. This literature review includes contemporary information on the biological activity, metabolism and pharmacological properties of cannabinoids and cannabinoid-like compounds, as well as their receptors. We established that only a few studies were devoted to the relationship of non-endocannabinoid N-acylethanolamines with non-cannabinoid receptors, such as PPARs, GPCRs, and also with TRPs. We have focused on issues that were insufficiently covered in the published sources in order to identify gaps in existing knowledge and determine the prospects for scientific research.

Deciphering Complex Interactions in Bioactive Lipid Signaling

Lipids are usually viewed as metabolic fuel and structural membrane components. Yet, in recent years, different families of lipids able to act as authentic messengers between cells and/or intracellularly have been discovered. Such lipid signals have been shown to exert their biological activity via specific receptors that, by triggering distinct signal transduction pathways, regulate manifold pathophysiological processes in our body. Here, endogenous bioactive lipids produced from arachidonic acid (AA) and other poly-unsaturated fatty acids will be presented, in order to put into better perspective the relevance of their mutual interactions for health and disease conditions. To this end, metabolism and signal transduction pathways of classical eicosanoids, endocannabinoids and specialized pro-resolving mediators will be described, and the intersections and commonalities of their metabolic enzymes and binding receptors will be discussed. Moreover, the interactions of AA-derived signals with other bioactive lipids such as shingosine-1-phosphate and steroid hormones will be addressed.

The role of metabolic reprogramming of oxygen-induced macrophages in the dynamic changes of atherosclerotic plaques

Atherosclerosis (As) is a chronic vascular inflammatory disease. Macrophages are the most important immune cells in atherosclerotic plaques, and the phenotype of plaque macrophages shifts dynamically to adapt to changes in the plaque microenvironment. The aerobic microenvironment of early atherosclerotic plaques promotes the transformation of M2/alternatively activated macrophages mainly through oxidative phosphorylation; the anoxic microenvironment of advanced atherosclerotic plaques mainly promotes the formation of M1/classically activated macrophages through anaerobic glycolysis; and the adventitia angiogenesis of aged atherosclerotic plaques leads to an increase in the proportion of M2/M1 macrophages. Therefore, this review deeply elucidates the dynamic change mechanism of plaque macrophages and the regulation of plaque oxygen content and immune metabolism to find new targets for the treatment of As.

Small Molecule Activation of NAPE-PLD Enhances Efferocytosis by Macrophages

N -acyl-phosphatidylethanolamine hydrolyzing phospholipase D (NAPE-PLD) is a zinc metallohydrolase that hydrolyzes N -acyl-phosphatidylethanolamine (NAPEs) to form N -acyl-ethanolamides (NAEs) and phosphatidic acid. Several lines of evidence suggest that reduced NAPE-PLD activity could contribute to cardiometabolic diseases. For instance, NAPEPLD expression is reduced in human coronary arteries with unstable atherosclerotic lesions, defective efferocytosis is implicated in the enlargement of necrotic cores of these lesions, and NAPE-PLD products such as palmitoylethanolamide and oleoylethanolamide have been shown to enhance efferocytosis. Thus, enzyme activation mediated by a small molecule may serve as a therapeutic treatment for cardiometabolic diseases. As a proof-of-concept study, we sought to identify small molecule activators of NAPE-PLD. High-throughput screening followed by hit validation and primary lead optimization studies identified a series of benzothiazole phenylsulfonyl-piperidine carboxamides that variably increased activity of both mouse and human NAPE-PLD. From this set of small molecules, two NAPE-PLD activators (VU534 and VU533) were shown to increase efferocytosis by bone-marrow derived macrophages isolated from wild-type mice, while efferocytosis was significantly reduced in Napepld -/- BMDM or after Nape-pld inhibition. Together these studies demonstrate an essential role for NAPE-PLD in the regulation of efferocytosis and the potential value of NAPE-PLD activators as a strategy to treat cardiometabolic diseases.

Macrophage polarization states in atherosclerosis

Atherosclerosis, a chronic inflammatory condition primarily affecting large and medium arteries, is the main cause of cardiovascular diseases. Macrophages are key mediators of inflammatory responses. They are involved in all stages of atherosclerosis development and progression, from plaque formation to transition into vulnerable plaques, and are considered important therapeutic targets. Increasing evidence suggests that the modulation of macrophage polarization can effectively control the progression of atherosclerosis. Herein, we explore the role of macrophage polarization in the progression of atherosclerosis and summarize emerging therapies for the regulation of macrophage polarization. Thus, the aim is to inspire new avenues of research in disease mechanisms and clinical prevention and treatment of atherosclerosis.

Free fatty acids stabilize integrin β1via S-nitrosylation to promote monocyte-endothelial adhesion

Hyperlipidemia characterized by high blood levels of free fatty acids (FFAs) is important for the progression of inflammatory cardiovascular diseases. Integrin β₁ is a transmembrane receptor that drives various cellular functions, including differentiation, migration, and phagocytosis. However, the underlying mechanisms modifying integrin β₁ protein and activity in mediating monocyte/macrophage adhesion to endothelium remain poorly understood. In this study, we demonstrated that integrin β₁ protein underwent S-nitrosylation in response to nitrosative stress in macrophages. To examine the effect of elevated levels of FFA on the modulation of integrin β₁ expression, we treated the macrophages with a combination of oleic acid and palmitic acid (2:1) and found that FFA activated inducible nitric oxide synthase/nitric oxide and increased the integrin β₁ protein level without altering the mRNA level. FFA promoted integrin β₁ S-nitrosylation via inducible nitric oxide synthase/nitric oxide and prevented its degradation by decreasing binding to E3 ubiquitin ligase c-Cbl. Furthermore, we found that increased integrin α₄β₁ heterodimerization resulted in monocyte/macrophage adhesion to endothelium. In conclusion, these results provided novel evidence that FFA-stimulated N--O stabilizes integrin β₁via S-nitrosylation, favoring integrin α₄β₁ ligation to promote vascular inflammation.

GPR55 in B cells limits atherosclerosis development and regulates plasma cell maturation

Dissecting the pathways regulating the adaptive immune response in atherosclerosis is of particular therapeutic interest. Here we report that the lipid G-protein coupled receptor GPR55 is highly expressed by splenic plasma cells (PC), upregulated in mouse spleens during atherogenesis and human unstable or ruptured compared to stable plaques. Gpr55-deficient mice developed larger atherosclerotic plaques with increased necrotic core size compared to their corresponding controls. Lack of GPR55 hyperactivated B cells, disturbed PC maturation and resulted in immunoglobulin (Ig)G overproduction. B cell-specific Gpr55 depletion or adoptive transfer of Gpr55-deficient B cells was sufficient to promote plaque development and elevated IgG titers. In vitro, the endogenous GPR55 ligand lysophsophatidylinositol (LPI) enhanced PC proliferation, whereas GPR55 antagonism blocked PC maturation and increased their mitochondrial content. Collectively, these discoveries provide previously undefined evidence for GPR55 in B cells as a key modulator of the adaptive immune response in atherosclerosis.

Nanoformulation of Seaweed Eisenia bicyclis in Albumin Nanoparticles Targeting Cardiovascular Diseases: In Vitro and In Vivo Evaluation

Natural products, especially those derived from seaweeds, are starting to be seen as effective against various diseases, such as cardiovascular diseases (CVDs). This study aimed to design a novel oral formulation of bovine albumin serum nanoparticles (BSA NPs) loaded with an extract of Eisenia bicyclis and to validate its beneficial health effects, particularly targeting hypercholesterolemia and CVD prevention. Small and well-defined BSA NPs loaded with Eisenia bicyclis extract were successfully prepared exhibiting high encapsulation efficiency. Antioxidant activity and cholesterol biosynthesis enzyme 3-hydroxy-3 methylutaryl coenzyme A reductase (HMGR) inhibition, as well as reduction of cholesterol permeation in intestinal lining model cells, were assessed for the extract both in free and nanoformulated forms. The nanoformulation was more efficient than the free extract, particularly in terms of HMGR inhibition and cholesterol permeation reduction. In vitro cytotoxicity and in vivo assays in Wistar rats were performed to evaluate its safety and overall effects on metabolism. The results demonstrated that the Eisenia bicyclis extract and BSA NPs were not cytotoxic against human intestinal Caco-2 and liver HepG2 cells and were also safe after oral administration in the rat model. In addition, an innovative approach was adopted to compare the metabolomic profile of the serum from the animals involved in the in vivo assay, which showed the extract and nanoformulation's impact on CVD-associated key metabolites. Altogether, these preliminary results revealed that the seaweed extract and the nanoformulation may constitute an alternative natural dosage form which is safe and simple to produce, capable of reducing cholesterol levels, and consequently helpful in preventing hypercholesterolemia, the main risk factor of CVDs.

CCN1/Integrin α5β1 Instigates Free Fatty Acid-Induced Hepatocyte Lipid Accumulation and Pyroptosis through NLRP3 Inflammasome Activation

Hyperlipidemia with high blood levels of free fatty acids (FFA) is the leading cause of non-alcoholic steatohepatitis. CCN1 is a secreted matricellular protein that drives various cellular functions, including proliferation, migration, and differentiation. However, its role in mediating FFA-induced pro-inflammatory cell death and its underlying molecular mechanisms have not been characterized. In this study, we demonstrated that CCN1 was upregulated in the livers of obese mice. The increase in FFA-induced CCN1 was evaluated in vitro by treating hepatocytes with a combination of oleic acid and palmitic acid (2:1). Gene silencing using specific small interfering RNAs (siRNA) revealed that CCN1 participated in FFA-induced intracellular lipid accumulation, caspase-1 activation, and hepatocyte pyroptosis. Next, we identified integrin α₅β₁ as a potential receptor of CCN1. Co-immunoprecipitation demonstrated that the binding between CCN1 and integrin α₅β₁ increased in hepatocytes upon FFA stimulation in the livers of obese mice. Similarly, the protein levels of integrin α₅ and β₁ were increased in vitro and in vivo. Experiments with specific siRNAs confirmed that integrin α₅β₁ played a part in FFA-induced intracellular lipid accumulation, NLRP3 inflammasome activation, and pyroptosis in hepatocytes. In conclusion, these results provide novel evidence that the CCN1/integrin α₅β₁ is a novel mediator that drives hepatic lipotoxicity via NLRP3-dependent pyroptosis.

The Impaired Mechanism and Facilitated Therapies of Efferocytosis in Atherosclerosis

ABSTRACT

Cardiovascular disease is responsible for the largest number of deaths worldwide, and atherosclerosis is the primary cause. Apoptotic cell accumulation in atherosclerotic plaques leads to necrotic core formation and plaque rupture. Emerging findings show that the progression of atherosclerosis appears to suppress the elimination of apoptotic cells. Mechanistically, the reduced edibility of apoptotic cells, insufficient phagocytic capacity of phagocytes, downregulation of bridging molecules, and dysfunction in the polarization of macrophages lead to impaired efferocytosis in atherosclerotic plaques. This review focuses on the characteristics of efferocytosis in plaques and the therapeutic strategies aimed at promoting efferocytosis in atherosclerosis, which would provide novel insights for the development of antiatherosclerotic drugs based on efferocytosis.

Palmitoylethanolamide and Related ALIAmides for Small Animal Health: State of the Art

ALIAmides are a family of fatty acid amides whose name comes from their mechanism of action, i.e., the Autacoid Local Injury Antagonism (ALIA). Actually, the ALIAmide parent molecule, palmitoylethanolamide (PEA), is locally produced on demand from a cell membrane precursor in order to control immune-inflammatory cell responses, avert chronic non-resolving inflammation, and limit the resulting clinical signs. ALIAmide sister compounds, such as Adelmidrol and palmitoylglucosamine, share mechanisms of action with PEA and may also increase endogenous levels of PEA. Provided that their respective bioavailability is properly addressed (e.g., through decreasing the particle size through micronization), exogenously administered ALIAmides thus mimic or sustain the prohomeostatic functions of endogenous PEA. The aim of the present paper is to review the main findings on the use of ALIAmides in small animals as a tribute to the man of vision who first believed in this “according-to-nature” approach, namely Francesco della Valle. After briefly presenting some key issues on the molecular targets, metabolism, and pharmacokinetics of PEA and related ALIAmides, here we will focus on the preclinical and clinical studies performed in dogs and cats. Although more data are still needed, ALIAmides may represent a novel and promising approach to small animal health.

Synaptic Effects of Palmitoylethanolamide in Neurodegenerative Disorders

Increasing evidence strongly supports the key role of neuroinflammation in the pathophysiology of neurodegenerative diseases, such as Alzheimer’s disease, frontotemporal dementia, and amyotrophic lateral sclerosis. Neuroinflammation may alter synaptic transmission contributing to the progression of neurodegeneration, as largely documented in animal models and in patients’ studies. In the last few years, palmitoylethanolamide (PEA), an endogenous lipid mediator, and its new composite, which is a formulation constituted of PEA and the well-recognized antioxidant flavonoid luteolin (Lut) subjected to an ultra-micronization process (co-ultraPEALut), has been identified as a potential therapeutic agent in different disorders by exerting potential beneficial effects on neurodegeneration and neuroinflammation by modulating synaptic transmission. In this review, we will show the potential therapeutic effects of PEA in animal models and in patients affected by neurodegenerative disorders.

Effects of Ultramicronized N-Palmitoylethanolamine Supplementation on Tramadol and Oxycodone Analgesia and Tolerance Prevention

Chronic pain management requires increasing doses of opioids, the milestone of painkillers, which may result in the onset of tolerance with exacerbated side effects. Maintaining stable analgesia with low doses of opioids is thus imperative. N-palmitoylethanolamine (PEA) is an endogenous lipid compound endowed with pain-relieving as well as anti-inflammatory properties. The ultramicronized formulation of PEA was recently demonstrated to be able to modulate morphine’s effects, delaying tolerance and improving efficacy. To evaluate the possible application to other opioids, in this study, we analysed the capacity of ultramicronized PEA to regulate analgesia and tolerance induced by oxycodone and tramadol. Pre-emptive and continuative treatment with ultramicronized PEA (30 mg kg⁻¹, daily, per os) delayed the onset of opioid tolerance and enhanced opioid analgesia when it was acutely administered in association with tramadol (20 mg kg⁻¹, daily, subcutaneously) or oxycodone (0.5 mg kg⁻¹, daily, subcutaneously). Moreover, PEA exerted antinociceptive effects on tolerant rats, suggesting the use of PEA together with opioids for stable, long-lasting analgesia. To that purpose, the oxycodone dose needed to be increased from 0.3 mg kg⁻¹ (day 1) up to 1 mg kg⁻¹ (day 31) in the oxycodone + vehicle group; the tramadol dose was progressively enhanced from 15 mg kg⁻¹ to 50 mg kg⁻¹ in 31 days in the tramadol + vehicle group. Acute oral co-treatment with PEA (120 mg kg⁻¹) achieved the same analgesia without increasing the dose of both opioids. The behavioural effects of PEA on opioid chronic treatment paralleled a decrease in astrocyte activation in the dorsal horn of the spinal cord (a marker of the development of opioid tolerance) and with a modulation of mRNA expression of IL-6 and serpin-A3. In conclusion, pre- and co-administration of ultramicronized PEA delayed the development of tramadol tolerance, potentiating either oxycodone or tramadol analgesia and allowing a long-lasting analgesic effect with a low opioid dose regimen. The use of PEA is suggested for clinical purposes to support the opioid-based management of persistent pain.

Selective measurement of NAPE-PLD activity via a PLA1/2-resistant fluorogenic N-acyl-phosphatidylethanolamine analog

N-acyl-phosphatidylethanolamine (NAPE)-hydrolyzing phospholipase D (NAPE-PLD) is a zinc metallohydrolase enzyme that converts NAPEs to bioactive N-acyl-ethanolamides. Altered NAPE-PLD activity may contribute to pathogenesis of obesity, diabetes, atherosclerosis, and neurological diseases. Selective measurement of NAPE-PLD activity is challenging, however, because of alternative phospholipase pathways for NAPE hydrolysis. Previous methods to measure NAPE-PLD activity involved addition of exogenous NAPE followed by TLC or LC/MS/MS, which are time and resource intensive. Recently, NAPE-PLD activity in cells has been assayed using the fluorogenic NAPE analogs PED-A1 and PED6, but these substrates also detect the activity of serine hydrolase-type lipases PLA1 and PLA2. To create a fluorescence assay that selectively measured cellular NAPE-PLD activity, we synthesized an analog of PED-A1 (flame-NAPE) where the sn-1 ester bond was replaced with an N-methyl amide to create resistance to PLA1 hydrolysis. Recombinant NAPE-PLD produced fluorescence when incubated with either PED-A1 or flame-NAPE, whereas PLA1 only produced fluorescence when incubated with PED-A1. Furthermore, fluorescence in HepG2 cells using PED-A1 could be partially blocked by either biothionol (a selective NAPE-PLD inhibitor) or tetrahydrolipstatin (an inhibitor of a broad spectrum of serine hydrolase-type lipases). In contrast, fluorescence assayed in HepG2 cells using flame-NAPE could only be blocked by biothionol. In multiple cell types, the phospholipase activity detected using flame-NAPE was significantly more sensitive to biothionol inhibition than that detected using PED-A1. Thus, using flame-NAPE to measure phospholipase activity provides a rapid and selective method to measure NAPE-PLD activity in cells and tissues.

Plasma metabolomics-based reveals the treatment mechanism of ShenGui capsule for application to coronary heart disease in a rat model

Shen Gui capsule (SGC) has been demonstrated to have a significant treatment effect for coronary heart disease (CHD). Nevertheless, the holistic therapeutic mechanism of SGC in vivo remain poorly interpreted. We aimed to systematically explore the preventive effect and mechanism of SGC on CHD rats using plasma metabolomics strategy. Rat CHD model was established by left anterior descending coronary artery ligation (LAD). Echocardiography, histological analyses of the myocardium and biochemical assays on serum were used to confirm the successful establishment of the CHD model and therapeutic effects of SGC. Then, UHPLC-MS/MS-based plasma metabolomics was combined with multivariate data analysis to screen potential pharmaco biomarkers associated with SGC treatment in the LAD-induced rat CHD model. After SGC treatment, 12 abnormal metabolites considered as potiential pharmaco biomarkers recovered to near normal levels. These biomarkers were involved in several metabolic pathways, including fat and protein metabolism, phenylalanine metabolism, neuroactive ligand-receptor interaction, androgen receptor signaling pathway, and estrone metabolism.These results suggested that SGC achieves therapeutic action on CHD via regulating various aspects of the body such as energy metabolism, neurological disturbances and inflammation, and thus plays a significant role in the treatment of CHD and its complications. The study is useful to systematically understand and analyze the mechanism of SGC's "multipie pathways, multiple levels, multiple targets" prevention and treatment of CHD.

Palmitoylethanolamide Counteracts Enteric Inflammation and Bowel Motor Dysfunctions in a Mouse Model of Alzheimer's Disease

Palmitoylethanolamide (PEA), an endogenous lipid mediator, is emerging as a promising pharmacological agent in multiple neurodegenerative disorders for its anti-inflammatory and neuroprotective properties. However, its effects on enteric inflammation and colonic dysmotility associated with Alzheimer’s disease (AD) are lacking. This study was designed to investigate the beneficial effect of PEA administration in counteracting the enteric inflammation and relieving the bowel motor dysfunctions in an AD mouse model, SAMP8 mice. In addition, the ability of PEA in modulating the activation of enteric glial cells (EGCs), pivotally involved in the pathophysiology of bowel dysfunctions associated with inflammatory conditions, has also been examined. SAMP8 mice at 4 months of age were treated orally with PEA (5 mg/kg/day) for 2 months. SAMR1 animals were employed as controls. At the end of treatment, parameters dealing with colonic motility, inflammation, barrier integrity and AD protein accumulation were evaluated. The effect of PEA on EGCs was tested in cultured cells treated with lipopolysaccharide (LPS) plus β-amyloid 1–42 (Aβ). SAMP8 treated with PEA displayed: 1) an improvement of in vitro colonic motor activity, citrate synthase activity and intestinal epithelial barrier integrity and 2) a decrease in colonic Aβ and α-synuclein (α-syn) accumulation, S100-β expression as well as enteric IL-1β and circulating LPS levels, as compared with untreated SAMP8 mice. In EGCs, treatment with PEA counteracted the increment of S100-β, TLR-4, NF-κB p65 and IL-1β release induced by LPS and Aβ. These results suggest that PEA, under a condition of cognitive decline, prevents the enteric glial hyperactivation, reduces AD protein accumulation and counteracts the onset and progression of colonic inflammatory condition, as well as relieves intestinal motor dysfunctions and improves the intestinal epithelial barrier integrity. Therefore, PEA represents a viable approach for the management of the enteric inflammation and motor contractile abnormalities associated with AD.

The Role of PPAR Alpha in the Modulation of Innate Immunity

Peroxisome proliferator-activated receptor α is a potent regulator of systemic and cellular metabolism and energy homeostasis, but it also suppresses various inflammatory reactions. In this review, we focus on its role in the regulation of innate immunity; in particular, we discuss the PPARα interplay with inflammatory transcription factor signaling, pattern-recognition receptor signaling, and the endocannabinoid system. We also present examples of the PPARα-specific immunomodulatory functions during parasitic, bacterial, and viral infections, as well as approach several issues associated with innate immunity processes, such as the production of reactive nitrogen and oxygen species, phagocytosis, and the effector functions of macrophages, innate lymphoid cells, and mast cells. The described phenomena encourage the application of endogenous and pharmacological PPARα agonists to alleviate the disorders of immunological background and the development of new solutions that engage PPARα activation or suppression.

Ultramicronized Palmitoylethanolamide Inhibits NLRP3 Inflammasome Expression and Pro-Inflammatory Response Activated by SARS-CoV-2 Spike Protein in Cultured Murine Alveolar Macrophages

Despite its possible therapeutic potential against COVID-19, the exact mechanism(s) by which palmitoylethanolamide (PEA) exerts its beneficial activity is still unclear. PEA has demonstrated analgesic, anti-allergic, and anti-inflammatory activities. Most of the anti-inflammatory properties of PEA arise from its ability to antagonize nuclear factor-κB (NF-κB) signalling pathway via the selective activation of the PPARα receptors. Acting at this site, PEA can downstream several genes involved in the inflammatory response, including cytokines (TNF-α, Il-1β) and other signal mediators, such as inducible nitric oxide synthase (iNOS) and COX2. To shed light on this, we tested the anti-inflammatory and immunomodulatory activity of ultramicronized(um)-PEA, both alone and in the presence of specific peroxisome proliferator-activated receptor alpha (PPAR-α) antagonist MK886, in primary cultures of murine alveolar macrophages exposed to SARS-CoV-2 spike glycoprotein (SP). SP challenge caused a significant concentration-dependent increase in proinflammatory markers (TLR4, p-p38 MAPK, NF-κB) paralleled to a marked upregulation of inflammasome-dependent inflammatory pathways (NLRP3, Caspase-1) with IL-6, IL-1β, TNF-α over-release, compared to vehicle group. We also observed a significant concentration-dependent increase in angiotensin-converting enzyme-2 (ACE-2) following SP challenge. um-PEA concentration-dependently reduced all the analyzed proinflammatory markers fostering a parallel downregulation of ACE-2. Our data show for the first time that um-PEA, via PPAR-α, markedly inhibits the SP induced NLRP3 signalling pathway outlining a novel mechanism of action of this lipid against COVID-19.

Lysophosphatidylinositol, an Endogenous Ligand for G Protein-Coupled Receptor 55, Has Anti-inflammatory Effects in Cultured Microglia

Lysophosphatidylinositol (LysoPI), an endogenous ligand for G protein-coupled receptor (GPR) 55, has been known to show various functions in several tissues and cells; however, its roles in the central nervous system (CNS) are not well known. In particular, the detailed effects of LysoPI on microglial inflammatory responses remain unknown. Microglia is the immune cell that has important functions in maintaining immune homeostasis of the CNS. In this study, we explored the effects of LysoPI on inflammatory responses using the mouse microglial cell line BV-2, which was stimulated with lipopolysaccharide (LPS), and some results were confirmed also in rat primary microglia. LysoPI was found to reduce LPS-induced nitric oxide (NO) production and inducible NO synthase protein expression without affecting cell viability in BV-2 cells. LysoPI also suppressed intracellular generation of reactive oxygen species both in BV-2 cells and primary microglia and cytokine release in BV-2 cells. In addition, LysoPI treatment decreased phagocytic activity of LPS-stimulated BV-2 cells and primary microglia. The GPR55 antagonist CID16020046 completely inhibited LysoPI-induced downregulation of phagocytosis in BV-2 microglia, but did not affect the LysoPI-induced decrease in NO production. Our results suggest that LysoPI suppresses microglial phagocytosis via a GPR55-dependent pathway and NO production via a GPR55-independent pathway. LysoPI may contribute to neuroprotection in pathological conditions such as brain injury or neurodegenerative diseases, through its suppressive role in the microglial inflammatory response.

Macrophage Plasticity and Atherosclerosis Therapy

Atherosclerosis is a chronic disease starting with the entry of monocytes into the subendothelium and the subsequent differentiation into macrophages. Macrophages are the major immune cells in atherosclerotic plaques and are involved in the dynamic progression of atherosclerotic plaques. The biological properties of atherosclerotic plaque macrophages determine lesion size, composition, and stability. The heterogenicity and plasticity of atherosclerotic macrophages have been a hotspot in recent years. Studies demonstrated that lipids, cytokines, chemokines, and other molecules in the atherosclerotic plaque microenvironment regulate macrophage phenotype, contributing to the switch of macrophages toward a pro- or anti-atherosclerosis state. Of note, M1/M2 classification is oversimplified and only represent two extreme states of macrophages. Moreover, M2 macrophages in atherosclerosis are not always protective. Understanding the phenotypic diversity and functions of macrophages can disclose their roles in atherosclerotic plaques. Given that lipid-lowering therapy cannot completely retard the progression of atherosclerosis, macrophages with high heterogeneity and plasticity raise the hope for atherosclerosis regression. This review will focus on the macrophage phenotypic diversity, its role in the progression of the dynamic atherosclerotic plaque, and finally discuss the possibility of treating atherosclerosis by targeting macrophage microenvironment.

GPR119 and GPR55 as Receptors for Fatty Acid Ethanolamides, Oleoylethanolamide and Palmitoylethanolamide

Oleoylethanolamide and palmitoylethanolamide are members of the fatty acid ethanolamide family, also known as acylethanolamides. Their physiological effects, including glucose homeostasis, anti-inflammation, anti-anaphylactic, analgesia, and hypophagia, have been reported. They have affinity for different receptor proteins, including nuclear receptors such as PPARα, channels such as TRPV1, and membrane receptors such as GPR119 and GPR55. In the present review, the pathophysiological functions of fatty acid ethanolamides have been discussed from the perspective of receptor pharmacology and drug discovery.

Distribution and Dynamic Changes in Matrix Metalloproteinase (MMP)-2, MMP-9, and Collagen in an In Stent Restenosis Process

OBJECTIVE

The aim of this study was to observe the spatial distribution and dynamic changes of matrix metalloproteinase (MMP)-2, MMP-9, and collagen in in stent restenosis (ISR) and to explore their influence on ISR.

METHODS

Sixty Z type stents were implanted into the common iliac arteries of minipigs, which were divided into 10 groups (six in each group) according to euthanasia time (6 hours, and 1, 3, 7, 14, 28, 56, 84, 168, and 336 days). After the samples were harvested, haematoxylin and eosin staining, immunohistochemical staining, Western blotting, and Picrosirius red staining were performed for all groups.

RESULTS

ISR occurred in all six minipigs in the 56 day group (percentage diameter stenosis range 71.6%-79.2%, mean ± standard deviation 75.6% ± 2.5%). The percentage diameter stenosis decreased to 38.3% ± 2.7% at 336 days (p < .001). Immunohistochemical staining showed that MMP-2 and MMP-9 were strongly stained near the internal elastic lamina or in the damaged parts of the intima, around the struts and neointimal lumen surface in the ISR process. The expression of MMP-2 and MMP-9 at 56 days was significantly lower compared with their peaks (seven days and one day [p < .001; p = .002], respectively). At 56 days, the collagen content reached its maximum (mean integrated optical density range 0.73-0.92, mean ± standard deviation 0.82 ± 0.09). From the 14 day group to the 336 day group, mature collagen in neointima was correlated negatively with MMP-2 (γ(36) = -0.816; p < .001) and MMP-9 expression (γ(36) = -0.853; p < .001). During the neointimal regression period, new collagen in neointima was positively correlated with MMP-2 (γ(24) = 0.683; p < .001) and MMP-9 (γ(24) = 0.873; p < .001).

CONCLUSION

This study has demonstrated the spatial distribution of and dynamic changes in MMP-2, MMP-9, and collagen in ISR by simulating the process of neointima from generation to regression after stent implantation. When ISR occurred, MMP-2 and MMP-9 expression decreased and collagen content reached its maximum, which might contribute to ISR.

The Basal Pharmacology of Palmitoylethanolamide

Palmitoylethanolamide (PEA, N-hexadecanoylethanolamide) is an endogenous compound belonging to the family of N-acylethanolamines. PEA has anti-inflammatory and analgesic properties and is very well tolerated in humans. In the present article, the basal pharmacology of PEA is reviewed. In terms of its pharmacokinetic properties, most work has been undertaken upon designing formulations for its absorption and upon characterising the enzymes involved in its metabolism, but little is known about its bioavailability, tissue distribution, and excretion pathways. PEA exerts most of its biological effects in the body secondary to the activation of peroxisome proliferator-activated receptor-α (PPAR-α), but PPAR-α-independent pathways involving other receptors (Transient Receptor Potential Vanilloid 1 (TRPV1), GPR55) have also been identified. Given the potential clinical utility of PEA, not least for the treatment of pain where there is a clear need for new well-tolerated drugs, we conclude that the gaps in our knowledge, in particular those relating to the pharmacokinetic properties of the compound, need to be filled.

Immunotherapy for cardiovascular disease

The outcomes of the Canakinumab Anti-inflammatory Thrombosis Outcome Study (CANTOS) trial have unequivocally proven that inflammation is a key driver of atherosclerosis and that targeting inflammation, in this case by using an anti-interleukin-1β antibody, improves cardiovascular disease (CVD) outcomes. This is especially true for CVD patients with a pro-inflammatory constitution. Although CANTOS has epitomized the importance of targeting inflammation in atherosclerosis, treatment with canakinumab did not improve CVD mortality, and caused an increase in infections. Therefore, the identification of novel drug targets and development of novel therapeutics that block atherosclerosis-specific inflammatory pathways and exhibit limited immune-suppressive side effects, as pursued in our collaborative research centre, are required to optimize immunotherapy for CVD. In this review, we will highlight the potential of novel immunotherapeutic targets that are currently considered to become a future treatment for CVD.

Macrophage Biology in Cardiovascular Diseases

Macrophages have a key functional role in the pathogenesis of various cardiovascular diseases, such as atherosclerosis and aortic aneurysms. Their accumulation within the vessel wall leads to sustained local inflammatory responses characterized by secretion of chemokines, cytokines, and matrix protein degrading enzymes. Here, we summarize some recent findings on macrophage contribution to cardiovascular disease. We focus on the origin, survival/death, and phenotypic switching of macrophages within vessel walls.

Lipoproteins and lipids in cardiovascular disease: from mechanistic insights to therapeutic targeting

With cardiovascular disease being the leading cause of morbidity and mortality worldwide, effective and cost-efficient therapies to reduce cardiovascular risk are highly needed. Lipids and lipoprotein particles crucially contribute to atherosclerosis as underlying pathology of cardiovascular disease and influence inflammatory processes as well as function of leukocytes, vascular and cardiac cells, thereby impacting on vessels and heart. Statins form the first-line therapy with the aim to block cholesterol synthesis, but additional lipid-lowering drugs are sometimes needed to achieve low-density lipoprotein (LDL) cholesterol target values. Furthermore, beyond LDL cholesterol, also other lipid mediators contribute to cardiovascular risk. This review comprehensively discusses low- and high-density lipoprotein cholesterol, lipoprotein (a), triglycerides as well as fatty acids and derivatives in the context of cardiovascular disease, providing mechanistic insights into their role in pathological processes impacting on cardiovascular disease. Also, an overview of applied as well as emerging therapeutic strategies to reduce lipid-induced cardiovascular burden is provided.

A New Palmitoylethanolamide Form Combined with Antioxidant Molecules to Improve Its Effectivess on Neuronal Aging

Palmitoylethanolamide is a nutraceutical compound naturally produced in many plants and animal source foods, but the natural form is poorly water-soluble. It has demonstrated an anti-inflammatory role as a neuroprotective mediator, acting on several molecular targets of the central nervous system involved on brain aging process. In healthy adults, palmitoylethanolamide is an endogenous PPAR-α (peroxisome proliferator-activated receptor α) agonist through which it performs anti-inflammatory activity and provides its effects by activating the cannabinoid receptor. The different formulations of palmitoylethanolamide (micronized palmitoylethanolamide, FM-LipoMatrix^® palmitoylethanolamide and FM-LipoMatrix^® palmitoylethanolamide plus lipoic acid and vitamin D3) were analyzed starting from intestinal barrier, to verify their bioavailability, to in primary astrocytes in which cell viability, reactive oxygen species (ROS) and nitric oxide (NO) production, NFKB activity, MAPK, p53 and PPARα activities were investigated. Additionally, cannabinoid and estrogen receptors were analyzed using the western blot technique. The combination of palmitoylethanolamide in FM-LipoMatrix^®, lipoic acid and vitamin D3 shows better absorption predicting an improvement on plasma concentration; this formulation also shows a reduction in ROS and NO production and the data show the interaction of palmitoylethanolamide with cannabinoids and estrogen receptors inhibiting neuroinflammatory markers. All these data support the hypothesis of a new potential strategy to restore brain function and slow down brain aging in humans.

Palmitoylethanolamide and Related ALIAmides: Prohomeostatic Lipid Compounds for Animal Health and Wellbeing

Virtually every cellular process is affected by diet and this represents the foundation of dietary management to a variety of small animal disorders. Special attention is currently being paid to a family of naturally occurring lipid amides acting through the so-called autacoid local injury antagonism, i.e., the ALIA mechanism. The parent molecule of ALIAmides, palmitoyl ethanolamide (PEA), has being known since the 1950s as a nutritional factor with protective properties. Since then, PEA has been isolated from a variety of plant and animal food sources and its proresolving function in the mammalian body has been increasingly investigated. The discovery of the close interconnection between ALIAmides and the endocannabinoid system has greatly stimulated research efforts in this field. The multitarget and highly redundant mechanisms through which PEA exerts prohomeostatic functions fully breaks with the classical pharmacology view of “one drug, one target, one disease”, opening a new era in the management of animals’ health, i.e., an according-to-nature biomodulation of body responses to different stimuli and injury. The present review focuses on the direct and indirect endocannabinoid receptor agonism by PEA and its analogues and also targets the main findings from experimental and clinical studies on ALIAmides in animal health and wellbeing.

Role of the Endocannabinoidome in Human and Mouse Atherosclerosis

The Endocannabinoid (eCB) system and its role in many physiological and pathological conditions is well described and accepted, and includes cardiovascular disorders. However, the eCB system has been expanded to an "-ome"; the endocannabinoidome (eCBome) that includes endocannabinoid-related mediators, their protein targets and metabolic enzymes, many of which significantly impact upon cardiometabolic health. These recent discoveries are here summarized with a special focus on their potential involvement in atherosclerosis. We described the role of classical components of the eCB system (eCBs, CB1 and CB2 receptors) and eCB-related lipids, their regulatory enzymes and molecular targets in atherosclerosis. Furthermore, since increasing evidence points to significant cross-talk between the eCBome and the gut microbiome and the gut microbiome and atherosclerosis, we explore the possibility that a gut microbiome - eCBome axis has potential implications in atherosclerosis.

Melanocortin 3 receptor activation with [D-Trp8]-γ-MSH suppresses inflammation in apolipoprotein E deficient mice

The melanocortin MC₁ and MC₃ receptors elicit anti-inflammatory actions in leukocytes and activation of these receptors has been shown to alleviate arterial inflammation in experimental atherosclerosis. Thus, we aimed to investigate whether selective targeting of melanocortin MC₃ receptor protects against atherosclerosis. Apolipoprotein E deficient (ApoE^-/-) mice were fed high-fat diet for 12 weeks and randomly assigned to receive either vehicle (n = 11) or the selective melanocortin MC₃ receptor agonist [D-Trp(8)]-gamma-melanocyte-stimulating hormone ([D-Trp8]-γ-MSH; 15 μg/day, n = 10) for the last 4 weeks. Lesion size as well as macrophage and collagen content in the aortic root plaques were determined. Furthermore, leukocyte counts in the blood and aorta and cytokine mRNA expression levels in the spleen, liver and aorta were quantified. No effect was observed in the body weight development or plasma cholesterol level between the two treatment groups. However, [D-Trp8]-γ-MSH treatment significantly reduced plasma levels of chemokine (C-C motif) ligands 2, 4 and 5. Likewise, cytokine and adhesion molecule expression levels were reduced in the spleen and liver of γ-MSH-treated mice, but not substantially in the aorta. In line with these findings, [D-Trp8]-γ-MSH treatment reduced leukocyte counts in the blood and aorta. Despite reduced inflammation, [D-Trp8]-γ-MSH did not change lesion size, macrophage content or collagen deposition of aortic root plaques. In conclusion, the findings indicate that selective activation of melanocortin MC₃ receptor by [D-Trp8]-γ-MSH suppresses systemic and local inflammation and thereby also limits leukocyte accumulation in the aorta. However, the treatment was ineffective in reducing atherosclerotic plaque size.

A Guide to Targeting the Endocannabinoid System in Drug Design

The endocannabinoid system (ECS) is one of the most crucial systems in the human organism, exhibiting multi-purpose regulatory character. It is engaged in a vast array of physiological processes, including nociception, mood regulation, cognitive functions, neurogenesis and neuroprotection, appetite, lipid metabolism, as well as cell growth and proliferation. Thus, ECS proteins, including cannabinoid receptors and their endogenous ligands’ synthesizing and degrading enzymes, are promising therapeutic targets. Their modulation has been employed in or extensively studied as a treatment of multiple diseases. However, due to a complex nature of ECS and its crosstalk with other biological systems, the development of novel drugs turned out to be a challenging task. In this review, we summarize potential therapeutic applications for ECS-targeting drugs, especially focusing on promising synthetic compounds and preclinical studies. We put emphasis on modulation of specific proteins of ECS in different pathophysiological areas. In addition, we stress possible difficulties and risks and highlight proposed solutions. By presenting this review, we point out information pivotal in the spotlight of ECS-targeting drug design, as well as provide an overview of the current state of knowledge on ECS-related pharmacodynamics and show possible directions for needed research.

N-Acylethanolamine Acid Amidase (NAAA): Structure, Function, and Inhibition

N-Acylethanolamine acid amidase (NAAA) is an N-terminal cysteine hydrolase primarily found in the endosomal-lysosomal compartment of innate and adaptive immune cells. NAAA catalyzes the hydrolytic deactivation of palmitoylethanolamide (PEA), a lipid-derived peroxisome proliferator-activated receptor-α (PPAR-α) agonist that exerts profound anti-inflammatory effects in animal models. Emerging evidence points to NAAA-regulated PEA signaling at PPAR-α as a critical control point for the induction and the resolution of inflammation and to NAAA itself as a target for anti-inflammatory medicines. The present Perspective discusses three key aspects of this hypothesis: the role of NAAA in controlling the signaling activity of PEA; the structural bases for NAAA function and inhibition by covalent and noncovalent agents; and finally, the potential value of NAAA-targeting drugs in the treatment of human inflammatory disorders.

Oleoylethanolamide stabilizes atherosclerotic plaque through regulating macrophage polarization via AMPK-PPARα pathway

BACKGROUND

Atherosclerotic plaque rupture is the major trigger of acute cardiovascular risk events, and manipulation of M1/M2 macrophage homeostasis is an effective strategy for regulating atherosclerotic plaque stability. This study was aimed to illuminate the effects of oleoylethanolamide (OEA) on macrophage polarization and plaque stability.

METHODS

Macrophages derived from THP-1 were treated with OEA followed by LPS/IFN-γ, and the markers of M1, M2 macrophages were monitored by western blot, real-time PCR and immunofluorescence staining. The effect of OEA on macrophage polarization in the arch of aortic arteries was tested by immunofluorescence staining and western blot, and the plaque stability was completed by Masson's trichrome and hematoxylin and eosin (HE) in apolipoprotein E (ApoE)^-/- mice.

RESULTS

OEA treatment enhanced the expression of two classic M2 macrophage markers, macrophage mannose receptor (CD206) and transforming growth factor (TGF-β), while the expression of iNOS (M1 macrophages) was decreased in THP-1-derived macrophages. Blocking of PPARα using siRNA and inhibition of AMP-activated protein kinase (AMPK) by its inhibitor compound C attenuated the OEA-induced expression of M2 macrophage markers. In addition, OEA significantly suppressed M1, promoted M2 macrophage polarization, increased collagen content and decreased necrotic core size in atherosclerotic plaques in ApoE^-/- mice, which were linked with the expression of PPARα.

CONCLUSIONS

OEA improved atherosclerotic plaque stability through regulating macrophage polarization via AMPK-PPARα pathway.