5-HEPE reduces obesity and insulin resistance by promoting adipose tissue browning through GPR119/AMPK/PGC1α activation

Targeted lipidomic reveals dietary LA/n-3 PUFAs regulate inflammation and redox status via oxylipins in bivalves

Oxylipins are bioactive lipid mediators derived from fatty acids; however, a comprehensive investigation of oxylipin profiles is absent in bivalves. Moreover, the physiological functions and bioactivities of PUFA-derived oxylipins warrant further exploration. In this study, we found that appropriate dietary linoleic acid (LA)/n-3 PUFAs enhanced the growth of the clam Sinonovacula constricta and improved its survival under hydrogen peroxide (H2O2) stress. Targeted lipidomic showed that the high-LA diet increased accumulation of LA and LA-derived oxylipins. Interestingly, a similar pattern was observed for α-linolenic acid (ALA) and ALA-derived oxylipins, potentially contributing to the anti-inflammatory and antioxidant effects of this dietary pattern. However, dietary n-3 PUFAs provided greater protection against H2O2-induced damage. Dietary n-3 PUFAs significantly increased the levels of oxylipins derived from docosahexaenoic acid and eicosapentaenoic acid, particularly 14(S)-hydroxydocosahexaenoic acid (14(S)-HDHA) and 12-hydroxyeicosapentaenoic acid (12-HEPE). Furthermore, 14(S)-HDHA and 12-HEPE restored cell viability in hydrogen peroxide (H2O2)-treated RAW264.7 cells. Mechanistically, 12-HEPE inhibited nuclear factor kappa B (NF-κB) nuclear translocation while promoting nuclear translocation of nuclear factor erythroid 2-related factor 2 (Nrf2), thereby reducing inflammatory responses and enhancing antioxidant capacity. Additionally, 12-HEPE increased antioxidant activity and suppressed inflammatory gene expression in clam hemolymph cells. This study represents the first comprehensive evaluation of the oxylipin profile in bivalves, further emphasizing the importance of dietary n-3 PUFAs intake in shaping n-3 PUFA-derived oxylipins and consequently influencing inflammation and redox status. Additionally, our study revealed that 12-HEPE alleviates cell damage induced by H2O2, with NF-κB and Nrf2 being key pathways.

Endogenous Metabolites in Metabolic Diseases: Pathophysiologic Roles and Therapeutic Implications

Breakthroughs in metabolomics technology have revealed the direct regulatory role of metabolites in physiology and disease. Recent data have highlighted the bioactive metabolites involved in the etiology and prevention and treatment of metabolic diseases such as obesity, nonalcoholic fatty liver disease, type 2 diabetes mellitus, and atherosclerosis. Numerous studies reveal that endogenous metabolites biosynthesized by host organisms or gut microflora regulate metabolic responses and disorders. Lipids, amino acids, and bile acids, as endogenous metabolic modulators, regulate energy metabolism, insulin sensitivity, and immune response through multiple pathways, such as insulin signaling cascade, chemical modifications, and metabolite-macromolecule interactions. Furthermore, the gut microbial metabolites short-chain fatty acids, as signaling regulators have a variety of beneficial impacts in regulating energy metabolic homeostasis. In this review, we will summarize information about the roles of bioactive metabolites in the pathogenesis of many metabolic diseases. Furthermore, we discuss the potential value of metabolites in the promising preventive and therapeutic perspectives of human metabolic diseases.

Z-Spectral MRI Quantifies the Mass and Metabolic Activity of Adipose Tissues With Fat-Water-Fraction and Amide-Proton-Transfer Contrasts

BACKGROUND

Brown adipose tissue (BAT) is metabolically activatable and plays an important role in obesity and metabolic diseases. With reduced fat-water-fraction (FWF) compared with white adipose tissue (WAT), BAT mass and its functional activation may be quantified with Z-spectra MRI, with built-in FWF and the metabolic amide proton transfer (APT) contrasts.

PURPOSE

To investigate if Z-spectral MRI can quantify the mass and metabolic activity of adipose tissues.

STUDY TYPE

Prospective.

SUBJECTS

Seven groups of 8-week-old male rats, including two groups (n = 7 per group) for in vivo MRI study and five groups (n = 5 per group) for ex vivo validation; 12 young and healthy volunteers with 6 male and 6 female.

FIELD STRENGTH/SEQUENCE

The 7 T small animal and 3 T clinical systems, T2-weighted imaging, Rapid Acquisition with Relaxation Enhancement (RARE) readout based chemical exchange saturation transfer (CEST) Z-spectral MRI sequence.

ASSESSMENT

Quantified FWF and APT from Z-spectra in rats before and after norepinephrine (NE) stimulation and in healthy human subjects; ex vivo measurements of total proteins in BAT from rats.

STATISTICAL TESTS

Two-tailed unpaired Student's t-tests and repeated measures ANOVA. P-value <0.05 was considered significant.

RESULTS

Decreased FWF (from 39.6% ± 7.2% before NE injection to 16.4% ± 7.2% 120 minutes after NE injection, P < 0.0001) and elevated APT (from 1.1% ± 0.5% before NE injection to 2.9% ± 0.5% 120 minutes after NE injection, P < 0.0001) signals in BAT were observed with in vivo Z-spectral MRI in rats injected with NE at 7 T MRI. At clinical 3 T, Z-spectral MRI was used to quantify the FWF (58.5% ± 7.2% in BAT and 73.7% ± 6.5% in WAT with P < 0.0001) and APT (2.6% ± 0.8% in BAT and 0.9% ± 0.3% in WAT with P < 0.0001) signals in healthy volunteers. APT signals of BAT were negatively correlated with the BMI in humans (r = 0.71).

DATA CONCLUSION

Endogenous Z-spectral MRI was demonstrated to simultaneously quantify BAT mass and function based on its FWF and APT contrasts.

LEVEL OF EVIDENCE: 2

TECHNICAL EFFICACY STAGE

1.

Thermogenic adipose tissues: Promising therapeutic targets for metabolic diseases

The ongoing increase in the prevalence of obesity and its comorbidities such as cardiovascular disease, type 2 diabetes (T2D) and dyslipidemia warrants discovery of novel therapeutic options for these metabolic diseases. Obesity is characterized by white adipose tissue expansion due to chronic positive energy balance as a result of excessive energy intake and/or reduced energy expenditure. Despite various efforts to prevent or reduce obesity including lifestyle and behavioral interventions, surgical weight reduction approaches and pharmacological methods, there has been limited success in significantly reducing obesity prevalence. Recent research has shown that thermogenic adipocyte (brown and beige) activation or formation, respectively, could potentially act as a therapeutic strategy to ameliorate obesity and its related disorders. This can be achieved through the ability of these thermogenic cells to enhance energy expenditure and regulate circulating levels of glucose and lipids. Thus, unraveling the molecular mechanisms behind the formation and activation of brown and beige adipocytes holds the potential for probable therapeutic paths to combat obesity. In this review, we provide a comprehensive update on the development and regulation of different adipose tissue types. We also emphasize recent interventions in harnessing therapeutic potential of thermogenic adipocytes by bioactive compounds and new pharmacological anti-obesity agents.

Detection and Characterization of Multidimensional Information of Adipocyte Model Based on AFM-Raman

Excessive accumulation of white adipose tissue leads to metabolic disorders, and the excessive differentiation of preadipocytes into white adipocytes is one of the contributing factors to obesity. The browning of white adipocytes has been regarded as a promising therapeutic strategy. To analyze the origins and potential solutions for obesity from a fundamental perspective, we employed atomic force microscopy, and Raman confocal microscopy to investigate and characterize multidimensional information regarding the differentiation process of 3 T3-L1 preadipocyte models into white adipocytes and their subsequent browning into beige adipocytes. The results from atomic force microscopy indicated that during the differentiation of preadipocytes into mature white adipocytes, there was an increase in cell height, a decrease in length, and a transformation in shape from fibroblast-like morphology to spherical form. Additionally, Young's modulus, stiffness, and adhesion decreased throughout this process. Following browning, cells maintained their spherical shape but exhibited reduced height compared to white adipocytes; lipid droplet decomposition resulted in increased surface roughness. Raman spectroscopy studies revealed that preadipocytes lacked specific lipid peaks; however, as they differentiated into white adipocytes, peak Raman signals transitioned from weak to sharp. After browning occurred, lipid peak signals became sparse and dispersed. Furthermore, by calibrating temperature standard curves based on water molecule hydrogen-oxygen stretching bands, it was found that beige adipocytes possess thermogenic capabilities. Based on Segment Anything Model for lipid droplet segmentation and color clustering 3D K-Means point cloud analysis: White adipocyte lipid droplets aggregated with deeper coloration post-staining appearing duller; conversely, beige adipocyte coloration appeared lighter and brighter with more clusters present within the clustering point cloud. In summary, this study provides a novel method for multidimensional detection and characterization through an interdisciplinary approach combining cellular biology with physical chemistry.

Dietary Eicosapentaenoic Acid Improves Ozone-Induced Pulmonary Inflammation in C57BL/6 Mice

BACKGROUND

Ambient concentrations of the air pollutant, ozone, are rising with increasing global temperatures. Ozone is known to increase incidence and exacerbation of chronic lung diseases, which will increase as ambient ozone levels rise. Studies have identified diet as a variable that is able to modulate the pulmonary health effects associated with ozone exposure. Eicosapentaenoic acid (EPA) is an n-3 (ω-3) PUFA consumed through diet, which lowers inflammation through conversion to oxylipins including hydroxy-eicosapentaenoic acids (HEPEs). However, the role of dietary EPA in ozone-induced pulmonary inflammation is unknown.

OBJECTIVE

Therefore, we hypothesized increasing dietary EPA will decrease ozone-induced pulmonary inflammation and injury through the production of HEPEs.

METHODS

To test this, male C57BL/6J mice were fed a purified control diet or EPA-supplemented diet for 4 wk and then exposed to filtered air or 1 part per million ozone for 3 h. 24 or 48 h after exposure, bronchoalveolar lavage fluid was collected to assess airspace inflammation/injury and lung tissue was collected for targeted liquid chromatography-mass spectrometry lipidomics.

RESULTS

Following ozone exposure, EPA supplementation did not alter markers of lung injury but decreased ozone-induced airspace neutrophilia. Targeted liquid chromatography-mass spectrometry lipidomics revealed dietary EPA supplementation increased pulmonary EPA-derived metabolites including 5-HEPE and 12-HEPE. Additionally, EPA supplementation decreased pulmonary amounts of proinflammatory arachidonic acid-derived metabolites. To evaluate whether dietary EPA reduces ozone-induced pulmonary inflammation through increased pulmonary HEPEs, C57BL/6J mice were administered 5-HEPEs and 12-HEPEs systemically before filtered air or ozone exposure. Pretreatment with 5-HEPEs and 12-HEPEs reduced ozone-driven increases in airspace macrophages.

CONCLUSIONS

Together, these data indicate that an EPA-supplemented diet protects against ozone-induced airspace inflammation which is, in part, due to increasing pulmonary amounts of 5-HEPEs and 12-HEPEs. These findings suggest that dietary EPA and/or increasing EPA-derived metabolites in the lung can reduce ozone-driven incidences and exacerbations of chronic pulmonary diseases.

Oxylipins Derived from PUFAs in Cardiometabolic Diseases: Mechanism of Actions and Possible Nutritional Interactions

Oxylipins are oxidized fatty acids, both saturated and unsaturated, formed through pathways that involve singlet oxygen or dioxygen-mediated oxygenation reactions and are primarily produced by enzyme families such as cyclooxygenases, lipoxygenases, and cytochrome P450. These lipid-based complex bioactive molecules are pivotal signal mediators, acting in a hormone-like manner in the pathophysiology of numerous diseases, especially cardiometabolic diseases via modulating plenty of mechanisms. It has been reported that omega-6 and omega-3 oxylipins are important novel biomarkers of cardiometabolic diseases. Moreover, collected literature has noted that diet and dietary components, especially fatty acids, can modulate these oxygenated lipid products since they are mainly derived from dietary omega-3 and omega-6 polyunsaturated fatty acids (PUFAs) or linoleic acid and α-linolenic by elongation and desaturation pathways. This comprehensive review aims to examine their correlations to cardiometabolic diseases and how diets modulate oxylipins. Also, some aspects of developing new biomarkers and therapeutical utilization are detailed in this review.

Icosapent ethyl modulates circulating vascular regenerative cell content: The IPE-PREVENTION CardioLink-14 trial

BACKGROUND

REDUCE-IT (Reduction of Cardiovascular Events with Icosapent Ethyl-Intervention Trial) showed that icosapent ethyl (IPE) reduced major adverse cardiovascular events by 25%. Since the underlying mechanisms for these benefits are not fully understood, the IPE-PREVENTION CardioLink-14 trial (ClinicalTrials.gov: NCT04562467) sought to determine if IPE regulates vascular regenerative (VR) cell content in people with mild to moderate hypertriglyceridemia.

METHODS

Seventy statin-treated individuals with triglycerides ≥1.50 and <5.6 mmol/L and either atherosclerotic cardiovascular disease or type 2 diabetes with additional cardiovascular risk factors were randomized to IPE (4 g/day) or usual care. VR cells with high aldehyde dehydrogenase activity (ALDHhi) were isolated from blood collected at the baseline and 3-month visits and characterized with lineage-specific cell surface markers. The primary endpoint was the change in frequency of pro-vascular ALDHhiside scatter (SSC)lowCD133+ progenitor cells. Change in frequencies of ALDHhiSSCmid monocyte and ALDHhiSSChi granulocyte precursor subsets, reactive oxygen species production, serum biomarkers, and omega-3 levels were also evaluated.

FINDINGS

Baseline characteristics, cardiovascular risk factors, and medications were balanced between the groups. Compared to usual care, IPE increased the mean frequency of ALDHhiSSClowCD133+ cells (-1.00% ± 2.45% vs. +7.79% ± 1.70%; p = 0.02), despite decreasing overall ALDHhiSSClow cell frequency. IPE assignment also reduced oxidative stress in ALDHhiSSClow progenitors and increased ALDHhiSSChi granulocyte precursor cell content.

CONCLUSIONS

IPE-PREVENTION CardioLink-14 provides the first translational evidence that IPE can modulate VR cell content and suggests a novel mechanism that may underlie the cardioprotective effects observed with IPE in REDUCE-IT.

FUNDING

HLS Therapeutics provided the IPE in kind and had no role in the study design, conduct, analyses, or interpretation.

Synbiotic Bacillus megaterium DSM 32963 and n-3 PUFA Salt Composition Elevates Pro-Resolving Lipid Mediator Levels in Healthy Subjects: A Randomized Controlled Study

Beneficial health effects of omega-3 polyunsaturated fatty acids (n-3 PUFA) are partly attributed to specialized pro-resolving mediators (SPMs), which promote inflammation resolution. Strategies to improve n-3 PUFA conversion to SPMs may, therefore, be useful to treat or prevent chronic inflammatory disorders. Here, we explored a synbiotic strategy to increase circulating SPM precursor levels. Healthy participants (n = 72) received either SynΩ3 (250 mg eicosapentaenoic acid (EPA) plus docosahexaenoic acid (DHA) lysine salts; two billion CFU Bacillus megaterium; n = 23), placebo (n = 24), or fish oil (300 mg EPA plus DHA; N = 25) capsules daily for 28 days in a randomized, double-blind placebo-controlled parallel 3-group design. Biomarkers were assessed at baseline and after 2 and 28 days of intervention. The primary analysis involved the comparison between SynΩ3 and placebo. In addition, SynΩ3 was compared to fish oil. The synbiotic SynΩ3 comprising Bacillus megaterium DSM 32963 and n-3 PUFA salts significantly increased circulating SPM precursor levels, including 18-hydroxy-eicosapentaenoic acid (18-HEPE) plus 5-HEPE, which was not achieved to this extent by fish oil with a similar n-3 PUFA content. Omega-3 indices were increased slightly by both SynΩ3 and fish oil. These findings suggest reconsidering conventional n-3 PUFA supplementation and testing the effectiveness of SynΩ3 particularly in conditions related to inflammation.

Ablation of histone methyltransferase Suv39h2 in hepatocytes attenuates NASH in mice

AIMS

Non-alcoholic steatohepatitis (NASH) is characterized by aberrant lipid metabolism in hepatocytes. We investigated the involvement of a histone H3K9 methyltransferase Suv39h2 in the pathogenesis of NASH.

METHODS AND MATERIALS

NASH is induced by feeding the mice with a high-fat high-carbohydrate (HFHC) diet or a high-fat choline-deficient amino acid defined (HFD-CDAA) diet. The Suv39h2f/f mice were crossbred with the Alb-Cre mice to specifically delete Suv39h2 in hepatocytes.

KEY FINDINGS

Ablation of Suv39h2 in hepatocytes improved insulin sensitivity of the mice fed either the HFHC diet or the CDAA-HFD diet. Importantly, Suv39h2 deletion significantly ameliorated NAFLD as evidenced by reduced lipid accumulation, inflammation, and fibrosis in the liver. RNA-seq uncovered Vanin-1 (Vnn1) as a novel transcriptional target for Suv39h2. Mechanistically, Suv39h2 repressed Vnn1 transcription in hepatocytes exposed to free fatty acids. Consistently, Vanin-1 knockdown normalized lipid accumulation in Suv39h2-null hepatocytes. Importantly, a significant correlation between Suv39h2, Vanin-1, and hepatic triglyceride levels was identified in NASH patients.

SIGNIFICANCE

Our study uncovers a novel mechanism whereby Suv39h2 may contribute to NASH pathogenesis and suggests that targeting the Suv39h2-Vanin-1 axis may yield novel therapeutic solutions against NASH.

Effect of L. Plantarum Y279 and W. Cibaria Y113 on microorganism, lipid oxidation and fatty acid metabolites in Yu jiaosuan, A Chinese tradition fermented snack

Fatty acids are one of the main sources of flavour in fermented Yu jiaosuan (YJS) in southwest China. Bacilli (50.18 %) and Oxyphotobacteria (32.70 %) were the dominant class. Lactiplantibacillus (40.51 %) and Weissella (20.43 %) were the dominant species in the inoculated fermented group (HY). The peroxide value (ZY: 0.025 g/100 g, HY: 0.016 g/100 g) and lipoxygenase (LOX) (ZY: 5.7654 U/min·g, HY: 3.3856 U/min·g) in the HY group were significantly lower compared with the natural fermentation group (ZY), while acid lipase activity (ZY: 0.3184 U/h·g, HY: 0.7075 U/h·g) and neutral lipase activity (ZY: 12.65443 U/h·g, HY: 20.25142 U/h·g) were significantly higher than the control sample. Totally 40 differential fatty acid metabolites were screened. Arachidonic acid metabolism, unsaturated fatty acid biosynthesis and linoleic acid metabolism were potential metabolic pathways. Seven major bacterial species were closely associated with 15 differential fatty acid. This study contributes to the targeted production of fatty acid functional active substances of YJS.

Effect of 2'-Fucosyllactose on Beige Adipocyte Formation in 3T3-L1 Adipocytes and C3H10T1/2 Cells

2'-Fucosyllactose (2'-FL), the functional oligosaccharide naturally present in milk, has been shown to exert health benefits. This study was aimed to investigate the effect of 2'-fucosyllactose (2'-FL) on the browning of white adipose tissue in 3T3-L1 adipocytes and C3H10T1/2 cells. The results revealed that 2'-FL decreased lipid accumulations with reduced intracellular triglyceride contents in vitro. 2'-FL intervention increased the mitochondria density and the proportion of UCP1-positive cells. The mRNA expressions of the mitochondrial biogenesis-related and browning markers (Cox7a, Cyto C, Tfam, Ucp1, Pgc1α, Prdm16, Cidea, Elovl3, Pparα, CD137, and Tmem26) were increased after 2'-FL intervention to some extent. Similarly, the protein expression of the browning markers, including UCP1, PGC1α, and PRDM16, was up-regulated in the 2'-FL group. Additionally, an adenosine monophosphate-activated protein kinase (AMPK) inhibitor, compound C (1 μM), significantly decreased the induction of thermogenic proteins expressions mediated by 2'-FL, indicating that the 2'-FL-enhanced beige cell formation was partially dependent on the AMPK pathway. In conclusion, 2'-FL effectively promoted the browning of white adipose in vitro.