Modulation of the mRNA of the Nlrp3 inflammasome by Morin and PUFAs in an obesity model induced by a high-fat diet

Combination therapy of metformin and morin attenuates insulin resistance, inflammation, and oxidative stress in skeletal muscle of high-fat diet-fed mice

Lipid accumulation, inflammation, and oxidative stress are the most important causes of muscle insulin resistance. The aim of this study was to investigate the single and combined treatment effects of metformin (MET) and morin (MOR) on lipid accumulation, inflammation, and oxidative stress in the skeletal muscle of mice fed a high-fat diet. The mice were supplemented with MET (230 mg/kg diet), MOR (100 mg/kg diet), and MET + MOR for 9 weeks. Our results revealed that single treatment with MET or MOR, and with a stronger effect of MET + MOR combined treatment, reduced body weight gain, improved glucose intolerance and enhanced Akt phosphorylation in the muscle tissue. In addition, plasma and muscle triglyceride levels were decreased after treatment with MET and MOR. The expression of genes involved in macrophage infiltration and polarization and pro-inflammatory cytokines showed that MET + MOR combined treatment, significantly reduced inflammation in the muscle. Furthermore, combined treatment of MET + MOR with greater efficacy than the single treatment improved several oxidative stress markers in the muscle. Importantly, combined treatment of MET and MOR could increase the expression of nuclear factor erythroid 2-related factor 2, the master regulator of the antioxidant response. These findings suggest that combination of MET with MOR might ameliorate insulin resistance, inflammation, and oxidative stress in the skeletal muscle of mice fed high-fat diet.

Polyphenols as NLRP3 inflammasome modulators in cardiometabolic diseases: a review of in vivo studies

The nucleotide-binding domain and leucine-rich repeat containing receptors (NLRs) are components of the innate immune system, important in coordinating the inflammatory response. Among them, NLRP3 can form inflammasomes, multiprotein complexes activating the inflammatory caspase-1 and leading, through a cell death-mediated signaling cascade, to the release of several proinflammatory cytokines. Dietary polyphenols, plant secondary metabolites, have been reported to exhibit anti-inflammatory properties, although studies have focused most on their effect on the expression of the final circulating cytokines rather than on the upstream signals activating the NLRP3 inflammasome. The present review explores current knowledge on the potential of dietary polyphenols to regulate the whole NLRP3 inflammasome pathway, in the context of cardiometabolic pathologies (obesity, cardiovascular diseases, type 2 diabetes and non-alcoholic fatty liver disease), based on in vivo studies. A clear tendency towards a decrease in the expression of the whole NLRP3 inflammasome signaling pathway when several animal models were supplemented with polyphenols was observed, commonly showing a dose-response effect; these modifications were concomitant with clinical improvements in the pathologies. Nevertheless, the diversity of doses used, the disparity in polyphenol structures tested and, particularly, the scarce clinical trials and exploration of mechanisms of action show the need to develop further research on the topic.

Whey protein hydrolysate alleviated atherosclerosis and hepatic steatosis by regulating lipid metabolism in apoE-/- mice fed a Western diet

Whey protein hydrolysate (WPH) has been proved to possess various biological activities associated with the amelioration of cardiovascular disease (CVD). The objective of this study was to investigate the anti-atherosclerotic and hepatoprotective effects of WPH on apolipoprotein E knockout (apoE^-/-) mice fed with a Western diet for 15 weeks. Results revealed that WPH markedly inhibited the development of atherosclerotic lesions in the aorta and steatosis injury in the liver. The serum lipid and inflammation levels were both reduced after WPH supplemented in apoE^-/- mice. In addition, WPH inhibited the lipid accumulation in the liver, thereby decreasing the hepatic inflammation level and oxidative stress injury. Mechanism investigation revealed that WPH down-regulated the expression of cholesterol biosynthesis genes while up-regulated the expression of cholesterol uptake and excretion genes in the liver. Meanwhile, the de novo lipogenesis was inhibited while the fatty acids β-oxidation was activated in the liver by WPH supplementation. Notably, the n-3 polyunsaturated fatty acid (PUFA)/n-6 PUFA ratio in serum and liver of the WPH-H group were 2.69-fold (p < 0.01) and 3.64-fold (p < 0.01) higher than that of the Model group. Collectively, our results proved WPH possesses potent anti-atherosclerotic and hepatoprotective activities and has the potential to be used as a novel functional ingredient for the management of CVD.

Modulatory Properties of Food and Nutraceutical Components Targeting NLRP3 Inflammasome Activation

Inflammasomes are key intracellular multimeric proteins able to initiate the cellular inflammatory signaling pathway. NLRP3 inflammasome represents one of the main protein complexes involved in the development of inflammatory events, and its activity has been largely demonstrated to be connected with inflammatory or autoinflammatory disorders, including diabetes, gouty arthritis, liver fibrosis, Alzheimer’s disease, respiratory syndromes, atherosclerosis, and cancer initiation. In recent years, it has been demonstrated how dietary intake and nutritional status represent important environmental elements that can modulate metabolic inflammation, since food matrices are an important source of several bioactive compounds. In this review, an updated status of knowledge regarding food bioactive compounds as NLRP3 inflammasome modulators is discussed. Several chemical classes, namely polyphenols, organosulfurs, terpenes, fatty acids, proteins, amino acids, saponins, sterols, polysaccharides, carotenoids, vitamins, and probiotics, have been shown to possess NLRP3 inflammasome-modulating activity through in vitro and in vivo assays, mainly demonstrating an anti-NLRP3 inflammasome activity. Plant foods are particularly rich in important bioactive compounds, each of them can have different effects on the pathway of inflammatory response, confirming the importance of the nutritional pattern (food model) as a whole rather than any single nutrient or functional compound.

Protective Effects of Sesamol against Liver Oxidative Stress and Inflammation in High-Fat Diet-Induced Hepatic Steatosis

Chronic high-fat diet (HFD) is associated with the onset and progression of hepatic steatosis, and oxidative stress is highly involved in this process. The potential role of sesamol (SEM) against oxidative stress and inflammation at the transcriptional level in a mice model of hepatic steatosis is not known. In this study, we aimed to investigate the scavenging effects of SEM towards reactive oxygen generated by lipid accumulation in the liver of obese mice and to explore the mechanisms of protection. Markers of oxidative stress, vital enzymes involved in stimulating oxidative stress or inflammation, and nuclear transcription of Nrf2 were examined. Our results showed that SEM significantly inhibited the activity of the HFD-induced hepatic enzymes CYP2E1 and NOX2, associated with oxidative stress generation. Additionally, SEM reversed HFD-induced activation of NF-κB, a redox-sensitive transcription factor, and attenuated the expression of hepatic TNF-α, a proinflammatory molecule. Moreover, SEM enhanced HFD-induced hepatic Nrf2 nuclear transcription and increased the levels of its downstream target genes Ho1 and Nqo1, which indicated antiinflammation and antioxidant properties. Our study suggests that chronic HFD led to hepatic steatosis, while SEM exhibited protective effects on the liver by counteracting the oxidative stress and inflammation induced by HFD. The underlying mechanism might involve multiple pathways at the transcriptional level; the antioxidant defense mechanism was in partly mediated by the upregulation of Nrf2.

Regulation of Inflammasomes by Application of Omega-3 Polyunsaturated Fatty Acids in a Spinal Cord Injury Model

Omega-3 polyunsaturated fatty acids (PUFA n3) ameliorate inflammation in different diseases and potentially improve neurological function after neuronal injury. Following spinal cord injury (SCI), inflammatory events result in caspase-1 mediated activation of interleukin-1 beta (IL-1b) and 18. We aim to evaluate the neuroprotective potency of PUFA n3 in suppressing the formation and activation of inflammasomes following SCI. Male Wistar rats were divided into four groups: control, SCI, SCI+PUFA n3, and SCI+Lipofundin MCT (medium-chain triglyceride; vehicle). PUFA n3 or vehicle was intravenously administered immediately after SCI and every 24 h for the next three days. We analyzed the expression of NLRP3, NLRP1, ASC, caspase-1, IL-1b, and 18 in the spinal cord. The distribution of microglia, oligodendrocytes, and astrocytes was assessed by immunohistochemistry analysis. Behavioral testing showed significantly improved locomotor recovery in PUFA n3-treated animals and the SCI-induced upregulation of inflammasome components was reduced. Histopathological evaluation confirmed the suppression of microgliosis, increased numbers of oligodendrocytes, and the prevention of demyelination by PUFA n3. Our data support the neuroprotective role of PUFA n3 by targeting the NLRP3 inflammasome. These findings provide evidence that PUFA n3 has therapeutic effects which potentially attenuate neuronal damage in SCI and possibly also in other neuronal injuries.

Peroxisome Proliferator-Activated Receptors (PPARs) and Oxidative Stress in Physiological Conditions and in Cancer

Peroxisome proliferator-activated receptors (PPARs) belong to the nuclear hormone receptor superfamily. Originally described as “orphan nuclear receptors”, they can bind both natural and synthetic ligands acting as agonists or antagonists. In humans three subtypes, PPARα, β/δ, γ, are encoded by different genes, show tissue-specific expression patterns, and contribute to the regulation of lipid and carbohydrate metabolisms, of different cell functions, including proliferation, death, differentiation, and of processes, as inflammation, angiogenesis, immune response. The PPAR ability in increasing the expression of various antioxidant genes and decreasing the synthesis of pro-inflammatory mediators, makes them be considered among the most important regulators of the cellular response to oxidative stress conditions. Based on the multiplicity of physiological effects, PPAR involvement in cancer development and progression has attracted great scientific interest with the aim to describe changes occurring in their expression in cancer cells, and to investigate the correlation with some characteristics of cancer phenotype, including increased proliferation, decreased susceptibility to apoptosis, malignancy degree and onset of resistance to anticancer drugs. This review focuses on mechanisms underlying the antioxidant and anti-inflammatory properties of PPARs in physiological conditions, and on the reported beneficial effects of PPAR activation in cancer.

White Button Mushroom Extracts Modulate Hepatic Fibrosis Progression, Inflammation, and Oxidative Stress In Vitro and in LDLR-/- Mice

Liver fibrosis can be caused by non-alcoholic steatohepatitis (NASH), among other conditions. We performed a study to analyze the effects of a nontoxic, water-soluble extract of the edible mushroom Agaricus bisporus (AB) as a potential inhibitor of fibrosis progression in vitro using human hepatic stellate cell (LX2) cultures and in vivo in LDLR-/- mice. Treatment of LX2 cells with the AB extract reduced the levels of fibrotic and oxidative-related markers and increased the levels of GATA4 expression. In LDLR-/- mice with high-fat diet (HFD)-induced liver fibrosis and inflammation, the progression of fibrosis, oxidative stress, inflammation, and apoptosis were prevented by AB extract treatment. Moreover, in the mouse model, AB extract could exert an antiatherogenic effect. These data suggest that AB mushroom extract seems to exert protective effects by alleviating inflammation and oxidative stress during the progression of liver fibrosis, possibly due to a decrease in Toll-like receptor 4 (TLR4) expression and a reduction in Nod-like receptor protein 3 (NLRP3) inflammasome activation. In addition, we observed a potential atheroprotective effect in our mouse model.

Lipidomic analysis of non-esterified furan fatty acids and fatty acid compositions in dietary shellfish and salmon by UHPLC/LTQ-Orbitrap-MS

Lipids such as furan fatty acids (F-acids) are the valuable minor bioactive components of food such as fatty fish and plants. They are reported to have positive health benefits, including antioxidant and anti-inflammatory activities. Despite their importance, limited studies are focusing on F-acid determination in dietary seafood. This study aimed to identify and profile non-esterified F-acids and free fatty acids in total lipid extract of seafood such as shellfish and salmon. The lipidomic analysis using liquid chromatography-linear trap quadrupole-orbitrap mass spectrometry led to identifying seven types of free F-acids in shellfish (n = 5) and salmon (n = 4). The identified F-acids were confirmed by their high-resolution masses and acquired mass spectra. The relative concentrations of F-acids in shellfish range from 0.01 to 10.93 mg/100 g of the fillet, and in salmon, 0.01 to 14.21 mg/100 g of the fillet. The results revealed the highest abundance of F-acids in Sakhalin surf clam, Japanese scallop, and a fatty salmon trout. Besides, relative levels of saturated, monounsaturated, and polyunsaturated fatty acids (PUFAs) in these seafoods were compared with each other, suggesting basket clams and salmon trout to have significantly higher levels of PUFAs. The dietary seafoods enriched with F-acids and PUFAs may have possible health benefits. Hence, the applied technique could be a promising tool for rapid detection and analysis of non-esterified fatty acids in food.