Oleoylethanolamide Reduces Hepatic Oxidative Stress and Endoplasmic Reticulum Stress in High-Fat Diet-Fed Rats

STING1-accelerated vascular smooth muscle cell senescence-associated vascular calcification in diabetes is ameliorated by oleoylethanolamide via improved mitochondrial DNA oxidative damage

Vascular calcification is a prevalent hallmark of cardiovascular risk in elderly and diabetic individuals. Senescent vascular smooth muscle cells (VSMCs) participate in calcification; however, the associated underlying mechanisms remain unknown. Aberrant activation of the cytosolic DNA sensing adaptor stimulator of interferon gene 1 (STING1) caused by cytosolic DNA, particularly that leaked from damaged mitochondria, is a catalyst for aging-related diseases. Although oleoylethanolamide (OEA) is an endogenous bioactive lipid mediator with lipid overload-associated vasoprotective effects, its benefit in diabetic vascular calcification remains uncharacterized. This study focused on the role of STING1 in mitochondrial dysfunction-mediated calcification and premature VMSC senescence in diabetes and the effects of OEA on these pathological processes. In diabetic in vivo rat/mouse aorta calcification models and an in vitro VSMC calcification model induced by Nε-carboxymethyl-lysine (CML), senescence levels, STING1 signaling activation, and mitochondrial damage markers were significantly augmented; however, these alterations were markedly alleviated by OEA, partially in a nuclear factor erythroid 2-related factor 2 (Nrf2)-dependent manner, and similar anti-calcification and senescence effects were observed in STING1-knockout mice and STING1-knockdown VSMCs. Mechanistically, mitochondrial DNA (mtDNA) damage was aggravated by CML in a reactive oxygen species-dependent manner, followed by mtDNA leakage into the cytosol, contributing to VSMC senescence-associated calcification via STING1 pathway activation. OEA treatment significantly attenuated the aforementioned cytotoxic effects of CML by enhancing cellular antioxidant capacity through the maintenance of Nrf2 translocation to the nucleus. Collectively, targeting STING1, a newly defined VSMC senescence regulator, contributes to anti-vascular calcification effects.

Sustained feeding of a diet high in fat resulted in a decline in the liver's insulin-degrading enzyme levels in association with the induction of oxidative and endoplasmic reticulum stress in adult male rats: Evaluation of 4-phenylbutyric acid

The current study explored the impact of high fat diet (HFD) on hepatic oxidative and endoplasmic reticulum (ER) stress and its insulin degrading enzyme (IDE) content with the injection of 4-phenyl butyric acid (4-PBA) in adult male rats. Following the weaning period, male offspring were distributed among six distinct groups. The corresponding diet was used for 20 weeks, subsequently 4-PBA was administered for three consecutive days. Plasma glucose and insulin levels, HOMA-β (homeostasis model assessment of β-cell), hepatic ER and oxidative stress biomarkers and IDE protein content were assessed. Long-term ingestion of HFD (31 % cow butter) induced oxidative and ER stress in the liver tissue. Accordingly, a rise in the malondialdehyde (MDA) content and catalase enzyme activity and a decrease in the glutathione (GSH) content were detected within the liver of the HFD and HFD + DMSO groups. Consumption of this diet elevated the liver expression of binding immunoglobulin protein (BIP) and C/enhancer-binding protein homologous protein (CHOP) levels while reduced its IDE content. The HOMA-β decreased significantly. The injection of the 4-PBA moderated all the induced changes. Findings from this study indicated that prolonged HFD consumption led to a reduction in plasma insulin levels, likely attributed to pancreatic β cell malfunction, as evidenced by a decline in the HOMA-β index. Also, the HFD appears to have triggered oxidative and ER stress in the liver, along with a decrease in its IDE content.

Autophagy and inflammation an intricate affair in the management of obesity and metabolic disorders: evidence for novel pharmacological strategies?

Unhealthy lifestyle habits including a sedentary life, the lack of physical activity, and wrong dietary habits are the major ones responsible for the constant increase of obesity and metabolic disorders prevalence worldwide; therefore, the scientific community pays significant attention to the pharmacotherapy of such diseases, beyond lifestyle interventions, the use of medical devices, and surgical approaches. The intricate interplay between autophagy and inflammation appears crucial to orchestrate fundamental aspects of cellular and organismal responses to challenging stimuli, including metabolic insults; hence, when these two processes are dysregulated (enhanced or suppressed) they produce pathologic effects. The present review summarizes the existing literature reporting the intricate affair between autophagy and inflammation in the context of metabolic disorders, including obesity, diabetes, and liver metabolic diseases (non-alcoholic fatty liver disease (NAFLD) and non-alcoholic steatohepatitis (NASH)). The evidence collected so far suggests that an alteration of autophagy might lead to maladaptive metabolic and inflammatory responses thus exacerbating the severity of the disease, and the most prominent conclusion underlies that autophagy might exert a protective function by contributing to balance inflammation. However, the complex nature of obesity and metabolic disorders might represent a limit of the studies; indeed, although many pharmacological treatments, producing positive metabolic effects, are also able to modulate autophagic flux and inflammation, it is not clear if the final beneficial effect might occur only by their mechanism of action, rather than because of additionally involved pathways. Finally, although future studies are needed, the observation that anti-obesity and antidiabetic drugs already on the market, including incretin mimetic agents, facilitate autophagy by dampening inflammation, strongly contributes to the idea that autophagy might represent a druggable system for the development of novel pharmacological tools that might represent an attractive strategy for the treatment of obesity and metabolic disorders.

Oleoylethanolamide protects mesenchymal stem/stromal cells (MSCs) from oxidative stress and reduces adipogenic related genes expression in adipose-derived MSCs undergoing adipocyte differentiation

BACKGROUND

Human mesenchymal stem/stromal cells (hMSCs) are known for their pronounced therapeutic potential; however, they are still applied in limited clinical cases for several reasons. ROS-mediated oxidative stress is among the chief causes of post-transplantation apoptosis and death of hMSCs. It has been reported that a strategy to protect hMSCs against ROS is to pretreat them with antioxidants. Oleoylethanolamide (OEA) is a monounsaturated fatty acid derived from oleic acid and it has many protective properties, including anti-obesity, anti-inflammatory, and antioxidant effects. OEA is also used as a weight loss supplement; due to its high affinity for the PPAR-α receptor, OEA increases the fat metabolism rate.

METHODS AND RESULTS

This study hence assessed the effects of OEA pretreatment on the in vitro survival rate and resistance of hMSCs under oxidative stress as well as the cellular and molecular events in the biology of stem/stromal cells affected by oxidative stress and free radicals. Considering the role of MSCs in adipogenesis and obesity, the expression of the main genes involved in adipogenesis was also addressed in this study. Results revealed that OEA increases the in vitro proliferation of MSCs and inhibits cell apoptosis by reducing the induction of oxidative stress. The results also indicated that OEA exerts its antioxidant properties by both activating the Nrf2/NQO-1/HO-1 signaling pathway and directly combating free radicals. Moreover, OEA can reduce adipogenesis through reducing the expression of PPARγ, leptin and CEBPA genes in hMSCs undergoing adipocyte differentiation.

CONCLUSIONS

Thus, OEA protects hMSCs from oxidative stress and reduces adipogenic related genes expression and can be regarded as a therapeutic agent for this purpose.

Transcriptomic (DNA Microarray) and Metabolome (LC-TOF-MS) Analyses of the Liver in High-Fat Diet Mice after Intranasal Administration of GALP (Galanin-like Peptide)

The aim of this research was to test the efficacy and potential clinical application of intranasal administration of galanin-like peptide (GALP) as an anti-obesity treatment under the hypothesis that GALP prevents obesity in mice fed a high-fat diet (HFD). Focusing on the mechanism of regulation of lipid metabolism in peripheral tissues via the autonomic nervous system, we confirmed that, compared with a control (saline), intranasally administered GALP prevented further body weight gain in diet-induced obesity (DIO) mice with continued access to an HFD. Using an omics-based approach, we identified several genes and metabolites in the liver tissue of DIO mice that were altered by the administration of intranasal GALP. We used whole-genome DNA microarray and metabolomics analyses to determine the anti-obesity effects of intranasal GALP in DIO mice fed an HFD. Transcriptomic profiling revealed the upregulation of flavin-containing dimethylaniline monooxygenase 3 (Fmo3), metallothionein 1 and 2 (Mt1 and Mt2, respectively), and the Aldh1a3, Defa3, and Defa20 genes. Analysis using the DAVID tool showed that intranasal GALP enhanced gene expression related to fatty acid elongation and unsaturated fatty acid synthesis and downregulated gene expression related to lipid and cholesterol synthesis, fat absorption, bile uptake, and excretion. Metabolite analysis revealed increased levels of coenzyme Q10 and oleoylethanolamide in the liver tissue, increased levels of deoxycholic acid (DCA) and taurocholic acid (TCA) in the bile acids, increased levels of taurochenodeoxycholic acid (TCDCA), and decreased levels of ursodeoxycholic acid (UDCA). In conclusion, intranasal GALP administration alleviated weight gain in obese mice fed an HFD via mechanisms involving antioxidant, anti-inflammatory, and fatty acid metabolism effects and genetic alterations. The gene expression data are publicly available at NCBI GSE243376.

"To brain or not to brain": evaluating the possible direct effects of the satiety factor oleoylethanolamide in the central nervous system

Introduction

Oleoylethanolamide (OEA), an endogenous N-acylethanolamine acting as a gut-to-brain signal to control food intake and metabolism, has been attracting attention as a target for novel therapies against obesity and eating disorders. Numerous observations suggested that the OEA effects might be peripherally mediated, although they involve central pathways including noradrenergic, histaminergic and oxytocinergic systems of the brainstem and the hypothalamus. Whether these pathways are activated directly by OEA or whether they are downstream of afferent nerves is still highly debated. Some early studies suggested vagal afferent fibers as the main route, but our previous observations have contradicted this idea and led us to consider the blood circulation as an alternative way for OEA's central actions.

Methods

To test this hypothesis, we first investigated the impact of subdiaphragmatic vagal deafferentation (SDA) on the OEA-induced activation of selected brain nuclei. Then, we analyzed the pattern of OEA distribution in plasma and brain at different time points after intraperitoneal administration in addition to measuring food intake.

Results

Confirming and extending our previous findings that subdiaphragmatic vagal afferents are not necessary for the eating-inhibitory effect of exogenous OEA, our present results demonstrate that vagal sensory fibers are also not necessary for the neurochemical effects of OEA. Rather, within a few minutes after intraperitoneal administration, we found an increased concentration of intact OEA in different brain areas, associated with the inhibition of food intake.

Conclusion

Our results support that systemic OEA rapidly reaches the brain via the circulation and inhibits eating by acting directly on selected brain nuclei.

Gut microbiota and oleoylethanolamide in the regulation of intestinal homeostasis

A vast literature strongly suggests that the endocannabinoid (eCB) system and related bioactive lipids (the paracannabinoid system) contribute to numerous physiological processes and are involved in pathological conditions such as obesity, type 2 diabetes, and intestinal inflammation. The gut paracannabinoid system exerts a prominent role in gut physiology as it affects motility, permeability, and inflammatory responses. Another important player in the regulation of host metabolism is the intestinal microbiota, as microorganisms are indispensable to protect the intestine against exogenous pathogens and potentially harmful resident microorganisms. In turn, the composition of the microbiota is regulated by intestinal immune responses. The intestinal microbial community plays a fundamental role in the development of the innate immune system and is essential in shaping adaptive immunity. The active interplay between microbiota and paracannabinoids is beginning to appear as potent regulatory system of the gastrointestinal homeostasis. In this context, oleoylethanolamide (OEA), a key component of the physiological systems involved in the regulation of dietary fat consumption, energy homeostasis, intestinal motility, and a key factor in modulating eating behavior, is a less studied lipid mediator. In the small intestine namely duodenum and jejunum, levels of OEA change according to the nutrient status as they decrease during food deprivation and increase upon refeeding. Recently, we and others showed that OEA treatment in rodents protects against inflammatory events and changes the intestinal microbiota composition. In this review, we briefly define the role of OEA and of the gut microbiota in intestinal homeostasis and recapitulate recent findings suggesting an interplay between OEA and the intestinal microorganisms.

N-Acetylcysteine Decreases Myocardial Content of Inflammatory Mediators Preventing the Development of Inflammation State and Oxidative Stress in Rats Subjected to a High-Fat Diet

Arachidonic acid (AA) is a key precursor for proinflammatory and anti-inflammatory derivatives that regulate the inflammatory response. The modulation of AA metabolism is a target for searching a therapeutic agent with potent anti-inflammatory action in cardiovascular disorders. Therefore, our study aims to determine the potential preventive impact of N-acetylcysteine (NAC) supplementation on myocardial inflammation and the occurrence of oxidative stress in obesity induced by high-fat feeding. The experiment was conducted for eight weeks on male Wistar rats fed a standard chow or a high-fat diet (HFD) with intragastric NAC supplementation. The Gas-Liquid Chromatography (GLC) method was used to quantify the plasma and myocardial AA levels in the selected lipid fraction. The expression of proteins included in the inflammation pathway was measured by the Western blot technique. The concentrations of arachidonic acid derivatives, cytokines and chemokines, and oxidative stress parameters were determined by the ELISA, colorimetric, and multiplex immunoassay kits. We established that in the left ventricle tissue NAC reduced AA concentration, especially in the phospholipid fraction. NAC administration ameliorated the COX-2 and 5-LOX expression, leading to a decrease in the PGE2 and LTC4 contents, respectively, and augmented the 12/15-LOX expression, increasing the LXA4 content. In obese rats, NAC ameliorated NF-κB expression, inhibiting the secretion of proinflammatory cytokines. NAC also affected the antioxidant levels in HFD rats through an increase in GSH and CAT contents with a simultaneous decrease in the levels of 4-HNE and MDA. We concluded that NAC treatment weakens the NF-κB signaling pathway, limiting the development of myocardial low-grade inflammation, and increasing the antioxidant content that may protect against the development of oxidative stress in rats with obesity induced by an HFD.

Effects of oleoylethanolamide supplementation on inflammatory biomarkers, oxidative stress and antioxidant parameters of obese patients with NAFLD on a calorie-restricted diet: A randomized controlled trial

Background: Oxidative stress is considered a major factor in the pathophysiology of non-alcoholic liver disease (NAFLD). A growing body of evidence indicates that oleoylethanolamide (OEA), a bioactive lipid mediator, has anti-inflammatory and antioxidant properties. This trial investigated the effects of OEA administration on inflammatory markers, oxidative stress and antioxidant parameters of patients with NAFLD. Methods: The present randomized controlled trial was conducted on 60 obese patients with NAFLD. The patients were treated with OEA (250 mg/day) or placebo along with a low-calorie diet for 12 weeks. Inflammatory markers and oxidative stress and antioxidant parameters were evaluated pre-and post-intervention. Results: At the end of the study, neither the between-group changes, nor the within-group differences were significant for serum levels of high-sensitivity C-reactive protein (hs-CRP), interleukin-1 beta (IL-1β), IL-6, IL-10, and tumor necrosis-factor α (TNF-α). Serum levels of total antioxidant capacity (TAC) and superoxide dismutase (SOD) significantly increased and serum concentrations of malondialdehyde (MDA) and oxidized-low density lipoprotein (ox-LDL) significantly decreased in the OEA group compared to placebo at study endpoint (p = 0.039, 0.018, 0.003 and 0.001, respectively). Although, no significant between-group alterations were found in glutathione peroxidase and catalase. There were significant correlations between percent of changes in serum oxidative stress and antioxidant parameters with percent of changes in some anthropometric indices in the intervention group. Conclusion: OEA supplementation could improve some oxidative stress/antioxidant biomarkers without any significant effect on inflammation in NAFLD patients. Further clinical trials with longer follow-up periods are demanded to verify profitable effects of OEA in these patients. Clinical Trial Registration: www.irct.ir, Iranian Registry of Clinical Trials IRCT20090609002017N32.

Electronic and Conventional Cigarette Exposure Aggravate Metabolic Parameters in High-Fat Diet-Induced Rats

BACKGROUND: The health implications of the perceived use of electronic cigarettes (e-cigarettes) are safer than conventional cigarettes on metabolic parameters are not clearly understood. The current study evaluates the metabolic parameters as the impact of cigarette and e-cigarette exposure in high-fat-diet (HFD)-induced rats. METHODS: Twenty-four male Wistar rats were divided into four groups: i) NC: normal control group; ii) HFD Alone; iii) HFD + Cig and iv) HFD + E-Cig, administered HFD followed by cigarette or e-cigarette exposure, respectively. Six cigarettes stick with nicotine 2 mg/stick and 2 ml of e-cigarette liquid with nicotine 6 mg/ml were used for 25 cycles of exposure. In the end, the rats were sacrificed and obtained blood for metabolic parameter analysis, consisting of lipid profile, glucose, uric acid, urea, creatinine, aspartate transaminase (AST), and alanine transaminase (ALT). Statistical analysis with One-Way ANOVA with post hoc was used for high-density lipoprotein (HDL), triglyceride, total cholesterol, glucose, uric acid, urea, and creatinine. Furthermore, Kruskal-Wallis with Mann-Whitney U was used for nonparametric data such as low-density lipoprotein (LDL), AST, and ALT. RESULTS: Data of all metabolic parameters were shown a significant increase in the group of HFD Alone, HFD + Cig, and HFD + E-Cig, otherwise HDL levels. Furthermore, HFD + Cig followed by HFD + E-Cig groups were significantly higher compared to HFD Alone group. CONCLUSION: E-cigarettes were shown to be less harmful than conventional cigarettes but did not guarantee it was safe. Both cigarettes and e-cigarettes aggravated metabolic parameters in HFD-induced rats.

Possible therapeutic effects of boron citrate and oleoylethanolamide supplementation in patients with COVID-19: A pilot randomized, double-blind, clinical trial

BACKGROUND

The present study aimed to assess the therapeutic effects of boron citrate and oleoylethanolamide supplementation in patients with COVID-19.

METHODS

Forty adult patients with a diagnosis of COVID-19 were recruited in the present study. Patients were randomized in a 1:1:1:1 allocation ratio to 1of 4 treatment groups: (A) 5 mg of boron citrate twice a day, (B) 200 mg of oleoylethanolamide twice a day, (C) both therapies, or (D) routine treatments without any study medications. At pre-and post-intervention phase, some clinical and biochemical parameters were assessed.

RESULTS

Supplementation with boron citrate alone or in combination with oleoylethanolamide significantly improved O2 saturation and respiratory rate (p < 0.01). At the end of the study, significant increases in white blood cell and lymphocyte count were observed in the boron citrate and combined groups (p < 0.001). Boron citrate supplementation led to a significant decrease in serum lactate dehydrogenase (p = 0.026) and erythrocyte sedimentation rate (p = 0.014), compared with other groups. Furthermore, boron citrate in combination with oleoylethanolamide resulted in a significant reduction in the high-sensitivity C-reactive protein and interleukin-1β concentrations (p = 0.031 and p = 0.027, respectively). No significant differences were found among four groups post-intervention, in terms of hemoglobin concentrations, platelet count, and serum interleukin-6 levels. At the end of the study, common symptoms of COVID-19 including cough, fatigue, shortness of breath, and myalgia significantly improved in the supplemented groups, compared to the placebo (p < 0.05).

CONCLUSION

Supplementation with boron citrate alone or in combination with oleoylethanolamide could improve some clinical and biochemical parameters in COVID-19 patients.

Acute Endoplasmic Reticulum Stress Induces Inflammation Reaction, Complement System Activation, and Lipid Metabolism Disorder of Piglet Livers: A Proteomic Approach

Endoplasmic reticulum stress (ERS) is closely associated with the occurrence and development of many liver diseases. ERS models mostly include experimental animals such as rats and mice. However, pigs are more similar to humans with regards to digestion and metabolism, especially liver construction, yet few reports on ERS in pigs exist. In order to explore changes in the liver under ERS, we used tunicamycin (TM), which can cause liver jaundice and damage liver function, to establish acute ERS models in piglets using a low TM dosage (LD, 0.1 mg/kg body weight (bw)), high TM dosage (HD, 0.3 mg/kg bw), or vehicle for 48 h. We found that both LD- and HD-induced ERS, as verified by the ERS-linked proteins. Furthermore, the concentrations of the proinflammatory cytokines, namely, TNF-α and IL-6 were elevated in TM-treated piglet livers, and the plasma levels of IL-6 and CRP were also higher, indicating the occurrence of inflammation in TM-treated piglets. The complement system was activated in TM-treated piglets, as indicated by increased levels of complement factors and activation products C3, C5a, and AP50. In order to gain insights into the global changes in liver proteins under ERS, we performed an isobaric tag for relative and absolute quantitation (iTRAQ)-based proteomic analysis on the livers of HD- and vehicle-treated piglets. Proteomic analysis identified 311 differentially expressed proteins (DEPs) between the two groups, and a Kyoto Encyclopedia of Genes and Genomes (KEGG) pathway analysis suggested that the DEPs were mainly enriched in signaling pathways such as metabolic pathways, protein processing in the endoplasmic reticulum, and complement and coagulation cascades. Many proteins involved in protein folding, lipid transport, and oxidation were upregulated. Proteins involved in lipid synthesis were downregulated to alleviate liver steatosis, and most complement factors were upregulated to protect the body, and Pearson correlation analysis found that most of the DEPs in the complement and coagulation pathway were significantly correlated with plasma CRP, IL6 and AP50. Our results revealed that TM can activate ERS, marked by liver injury and steatosis, inflammatory reactions, and complement activation in piglets.

(Wh)olistic (E)ndocannabinoidome-Microbiome-Axis Modulation through (N)utrition (WHEN) to Curb Obesity and Related Disorders

The discovery of the endocannabinoidome (eCBome) is evolving gradually with yet to be elucidated functional lipid mediators and receptors. The diet modulates these bioactive lipids and the gut microbiome, both working in an entwined alliance. Mounting evidence suggests that, in different ways and with a certain specialisation, lipid signalling mediators such as N-acylethanolamines (NAEs), 2-monoacylglycerols (2-MAGs), and N-acyl-amino acids (NAAs), along with endocannabinoids (eCBs), can modulate physiological mechanisms underpinning appetite, food intake, macronutrient metabolism, pain sensation, blood pressure, mood, cognition, and immunity. This knowledge has been primarily utilised in pharmacology and medicine to develop many drugs targeting the fine and specific molecular pathways orchestrating eCB and eCBome activity. Conversely, the contribution of dietary NAEs, 2-MAGs and eCBs to the biological functions of these molecules has been little studied. In this review, we discuss the importance of (Wh) olistic (E)ndocannabinoidome-Microbiome-Axis Modulation through (N) utrition (WHEN), in the management of obesity and related disorders.