Free fatty acids as modulators of the NLRP3 inflammasome in obesity/type 2 diabetes

MicroRNA-132 Negatively Regulates Palmitate-Induced NLRP3 Inflammasome Activation through FOXO3 Down-Regulation in THP-1 Cells

Saturated fatty acids were proposed to activate the NLRP3 inflammasome, a molecular platform that mediates the processing of interleukin (IL)-1β and IL-18. However, the mechanisms underlying the miRNA-mediated regulation of palmitate (PA)-induced inflammasome activation are unclear. We examined the role of miR-132 in PA-induced NLRP3 inflammasome activation in THP-1 cells. To understand the regulatory role of miR-132 in inflammasome activation, we either overexpressed or suppressed miR-132 in THP-1 cells that expressed the NLRP3 inflammasome in response to stimulation by PA. We analyzed the mRNA and protein levels of NLRP3, caspase-1 p10, IL-18, and IL-1β; caspase-1 activity; and IL-1β secretion. The presence of PA activated the NLRP3 inflammasome and increased miR-132 expression. Overexpression of miR-132 reduced caspase-1 p10, IL-18, and IL-1β, while the suppression of miR-132 enhanced inflammasome activation. In addition, miR-132 regulated the mRNA and protein expression of FOXO3, which is a potential target of miR-132 in these cells. FOXO3 suppression by small interfering RNA decreased NLRP3 inflammasome activity stimulated by PA. Knockdown of FOXO3 attenuated NLRP3 inflammasome activation by the miR-132 inhibitor. Based on these findings, we conclude that miR-132 negatively regulates PA-induced NLRP3 inflammasome activation through FOXO3 down-regulation in THP-1 cells.

Integrated Immunomodulatory Mechanisms through which Long-Chain n-3 Polyunsaturated Fatty Acids Attenuate Obese Adipose Tissue Dysfunction

Obesity is a global health concern with rising prevalence that increases the risk of developing other chronic diseases. A causal link connecting overnutrition, the development of obesity and obesity-associated co-morbidities is visceral adipose tissue (AT) dysfunction, characterized by changes in the cellularity of various immune cell populations, altered production of inflammatory adipokines that sustain a chronic state of low-grade inflammation and, ultimately, dysregulated AT metabolic function. Therefore, dietary intervention strategies aimed to halt the progression of obese AT dysfunction through any of the aforementioned processes represent an important active area of research. In this connection, fish oil-derived dietary long-chain n-3 polyunsaturated fatty acids (PUFA) in the form of eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA) have been demonstrated to attenuate obese AT dysfunction through multiple mechanisms, ultimately affecting AT immune cellularity and function, adipokine production, and metabolic signaling pathways, all of which will be discussed herein.

Lactobacillus johnsonii supplementation attenuates respiratory viral infection via metabolic reprogramming and immune cell modulation

Regulation of respiratory mucosal immunity by microbial-derived metabolites has been a proposed mechanism that may provide airway protection. Here we examine the effect of oral Lactobacillus johnsonii supplementation on metabolic and immune response dynamics during respiratory syncytial virus (RSV) infection. L. johnsonii supplementation reduced airway T helper type 2 cytokines and dendritic cell (DC) function, increased regulatory T cells, and was associated with a reprogrammed circulating metabolic environment, including docosahexanoic acid (DHA) enrichment. RSV-infected bone marrow-derived DCs (BMDCs) from L. johnsonii-supplemented mice had altered cytokine secretion, reduced expression of co-stimulatory molecules, and modified CD4+ T-cell cytokines. This was replicated upon co-incubation of wild-type BMDCs with either plasma from L. johnsonii-supplemented mice or DHA. Finally, airway transfer of BMDCs from L. johnsonii-supplemented mice or with wild-type derived BMDCs pretreated with plasma from L. johnsonii-supplemented mice reduced airway pathological responses to infection in recipient animals. Thus L. johnsonii supplementation mediates airway mucosal protection via immunomodulatory metabolites and altered immune function.

Sebaceous-immunobiology is orchestrated by sebum lipids

The major role of sebaceous glands in mammals is to produce sebum, which coats the epidermis and the hair providing waterproofing, thermoregulation and photoprotection. However, as the need for these functions decreased along the evolutionary changes in humans, a relevant question has been raised: are sebaceous glands and sebum the remnants of our mammalian heritage or do they have overtaken a far more complex role in human skin biology? Trying to provide answers to this question, this review introduces the evolving field of sebaceous immunobiology and puts into the focus the pathways that sebum lipids use to influence the immune milieu of the skin. By introducing possible modifiers of sebaceous lipogenesis and discussing the – human-specific – alterations in composition and amount of sebum, the attribute of sebum as a sensitive tool, which is capable of translating multiple signalling pathways into the dermal micro environment is presented. Further their interaction with macrophages and keratinocytes involves sebum lipid fractions into disease pathogenesis, which could lead – on the other side – to the development of novel sebum-based therapeutic strategies.

FFA4 (GPR120) as a fatty acid sensor involved in appetite control, insulin sensitivity and inflammation regulation

Unsaturated long-chain fatty acids have been suggested to be beneficial in the context of cardiovascular disorders based in epidemiologic studies conducted in Greenland and Mediterranean. DHA and EPA are omega-3 polyunsaturated fatty acids that are plentiful in fish oil, and oleic acid is an omega-9 monounsaturated fatty acid, rich in olive oil. Dietary intake of these unsaturated long-chain fatty acids have been associated with insulin sensitivity and weight loss, which contrasts with the impairment of insulin sensitivity and weight gain associated with high intakes of saturated long-chain fatty acids. The recent discovery that free fatty acid receptor 4 (FFA4, also known as GPR120) acts as a sensor for unsaturated long-chain fatty acids started to unveil the molecular mechanisms underlying the beneficial functions played by these unsaturated long-chain fatty acids in various physiological processes, which include the secretions of gastrointestinal peptide hormones and glucose homeostasis. In this review, the physiological roles and therapeutic significance of FFA4 in appetite control, insulin sensitization, and inflammation reduction are discussed in relation to obesity and type 2 diabetes from pharmacological viewpoints.

Current role of the NLRP3 inflammasome on obesity and insulin resistance: A systematic review

NLRP3 inflammasome activation seems to be a culprit behind the chronic inflammation characteristic of obesity and insulin resistance (IR). Nutrient excess generates danger-associated molecules that activate NLRP3 inflammasome-caspase 1, leading to maturation of IL-1β and IL-18, which are proinflammatory cytokines released by immune cells infiltrating the adipose tissue (AT) from obese subjects. Although several studies have reported an association of the NLRP3 inflammasome with obesity and/or IR; contradictory results were also reported by other studies. Therefore, we conducted a systematic review to summarize results of studies that evaluated the association of the NLRP3 with obesity and IR. Nineteen studies were included in the review. These studies focused on NLRP3 expression/polymorphism analyses in AT. Overall, human studies indicate that obesity and IR are associated with increased NLRP3 expression in AT. Studies in obese mice corroborate this association. Moreover, high fat diet (HFD) increases Nlrp3 expression in murine AT while calorie-restricted diet decreases its expression. Hence, Nlrp3 blockade in mice protects against HFD-induced obesity and IR. NLRP3 rs10754558 polymorphism is associated with risk for T2DM in Chinese Han populations. In conclusion, available studies strongly points for an association between NLRP3 inflammasome and obesity/IR.

Lipophagy maintains energy homeostasis in the kidney proximal tubule during prolonged starvation

Macroautophagy/autophagy is a self-degradation process that combats starvation. Lipids are the main energy source in kidney proximal tubular cells (PTCs). During starvation, PTCs increase fatty acid (FA) uptake, form intracellular lipid droplets (LDs), and hydrolyze them for use. The involvement of autophagy in lipid metabolism in the kidney remains largely unknown. Here, we investigated the autophagy-mediated regulation of renal lipid metabolism during prolonged starvation using PTC-specific Atg5-deficient (atg5-TSKO) mice and an in vitro serum starvation model. Twenty-four h of starvation comparably induced LD formation in the PTCs of control and atg5-TSKO mice; however, additional 24 h of starvation reduced the number of LDs in control mice, whereas increases were observed in atg5-TSKO mice. Autophagic degradation of LDs (lipophagy) in PTCs was demonstrated by electron microscopic observation and biochemical analysis. In vitro pulse-chase assays demonstrated that lipophagy mobilizes FAs from LDs to mitochondria during starvation, whereas impaired LD degradation in autophagy-deficient PTCs led to decreased ATP production and subsequent cell death. In contrast to the in vitro assay, despite impaired LD degradation, kidney ATP content was preserved in 48-h starved atg5-TSKO mice, probably due to increased utilization of ketone bodies. This compensatory mechanism was accompanied by a higher plasma FGF21 (fibroblast growth factor 21) level and its expression in the PTCs; however, this was not essential for the production of ketone bodies in the liver during prolonged starvation. In conclusion, lipophagy combats prolonged starvation in PTCs to avoid cellular energy depletion.

Role of free fatty acids in endothelial dysfunction

Plasma free fatty acids levels are increased in subjects with obesity and type 2 diabetes, playing detrimental roles in the pathogenesis of atherosclerosis and cardiovascular diseases. Increasing evidence showing that dysfunction of the vascular endothelium, the inner lining of the blood vessels, is the key player in the pathogenesis of atherosclerosis. In this review, we aimed to summarize the roles and the underlying mechanisms using the evidence collected from clinical and experimental studies about free fatty acid-mediated endothelial dysfunction. Because of the multifaceted roles of plasma free fatty acids in mediating endothelial dysfunction, elevated free fatty acid level is now considered as an important link in the onset of endothelial dysfunction due to metabolic syndromes such as diabetes and obesity. Free fatty acid-mediated endothelial dysfunction involves several mechanisms including impaired insulin signaling and nitric oxide production, oxidative stress, inflammation and the activation of the renin-angiotensin system and apoptosis in the endothelial cells. Therefore, targeting the signaling pathways involved in free fatty acid-induced endothelial dysfunction could serve as a preventive approach to protect against the occurrence of endothelial dysfunction and the subsequent complications such as atherosclerosis.

NLRP3 Inflammasome as a Molecular Marker in Diabetic Cardiomyopathy

Diabetic cardiomyopathy (DCM), a common consequence of longstanding diabetes mellitus, is initiated by death of cardiomyocyte. Hyperglycemia-induced reactive oxygen species (ROS) overproduction is a major contributor of the chronic low-grade inflammation that characterizes as the DCM. ROS may promote the activation of nucleotide-binding oligomerization domain like receptor (NLR) pyrin domain containing 3 (NLRP3) inflammasome, a novel regulator of inflammation and cell death, by nuclear factor-kB (NF-κB) and thioredoxin interacting/inhibiting protein (TXNIP). NLRP3 inflammasome regulates the death of cardiomyocyte and activation of fibroblast in DCM, which is involved in the structural and functional disorder of DCM. However, comprehensive understanding of molecular mechanisms linking NLRP3 inflammasome and disorder of cardiomyocyte and fibroblast in DCM is lacking. Here, we review the molecular mechanism(s) of NLRP3 inflammasome activation in response to hyperglycemia in DCM.

Interaction of the GCKR and A1CF loci with alcohol consumption to influence the risk of gout

BACKGROUND

Some gout-associated loci interact with dietary exposures to influence outcome. The aim of this study was to systematically investigate interactions between alcohol exposure and urate-associated loci in gout.

METHODS

A total of 2792 New Zealand European and Polynesian (Māori or Pacific) people with or without gout were genotyped for 29 urate-associated genetic variants and tested for a departure from multiplicative interaction with alcohol exposure in the risk of gout. Publicly available data from 6892 European subjects were used to test for a departure from multiplicative interaction between specific loci and alcohol exposure for the risk of hyperuricemia (HU). Multivariate adjusted logistic and linear regression was done, including an interaction term.

RESULTS

Interaction of any alcohol exposure with GCKR (rs780094) and A1CF (rs10821905) influenced the risk of gout in Europeans (interaction term 0.28, P = 1.5 × 10-4; interaction term 0.29, P = 1.4 × 10-4, respectively). At A1CF, alcohol exposure suppressed the gout risk conferred by the A-positive genotype. At GCKR, alcohol exposure eliminated the genetic effect on gout. In the Polynesian sample set, there was no experiment-wide evidence for interaction with alcohol in the risk of gout (all P > 8.6 × 10-4). However, at GCKR, there was nominal evidence for an interaction in a direction consistent the European observation (interaction term 0.62, P = 0.05). There was no evidence for an interaction of A1CF or GCKR with alcohol exposure in determining HU.

CONCLUSIONS

These data support the hypothesis that alcohol influences the risk of gout via glucose and apolipoprotein metabolism. In the absence of alcohol exposure, genetic variants in the GCKR and A1CF genes have a stronger role in gout.

Metabolic injury-induced NLRP3 inflammasome activation dampens phospholipid degradation

The collateral effects of obesity/metabolic syndrome include inflammation and renal function decline. As renal disease in obesity can occur independently of hypertension and diabetes, other yet undefined causal pathological pathways must be present. Our study elucidate novel pathological pathways of metabolic renal injury through LDL-induced lipotoxicity and metainflammation. Our in vitro and in vivo analysis revealed a direct lipotoxic effect of metabolic overloading on tubular renal cells through a multifaceted mechanism that includes intralysosomal lipid amassing, lysosomal dysfunction, oxidative stress, and tubular dysfunction. The combination of these endogenous metabolic injuries culminated in the activation of the innate immune NLRP3 inflammasome complex. By inhibiting the sirtuin-1/LKB1/AMPK pathway, NLRP3 inflammasome dampened lipid breakdown, thereby worsening the LDL-induced intratubular phospholipid accumulation. Consequently, the presence of NLRP3 exacerbated tubular oxidative stress, mitochondrial damage and malabsorption during overnutrition. Altogether, our data demonstrate a causal link between LDL and tubular damage and the creation of a vicious cycle of excessive nutrients-NLRP3 activation-catabolism inhibition during metabolic kidney injury. Hence, this study strongly highlights the importance of renal epithelium in lipid handling and recognizes the role of NLRP3 as a central hub in metainflammation and immunometabolism in parenchymal non-immune cells.

Gene-Diet Interactions in Type 2 Diabetes: The Chicken and Egg Debate

Consistent evidence from both experimental and human studies indicates that Type 2 diabetes mellitus (T2DM) is a complex disease resulting from the interaction of genetic, epigenetic, environmental, and lifestyle factors. Nutrients and dietary patterns are important environmental factors to consider in the prevention, development and treatment of this disease. Nutritional genomics focuses on the interaction between bioactive food components and the genome and includes studies of nutrigenetics, nutrigenomics and epigenetic modifications caused by nutrients. There is evidence supporting the existence of nutrient-gene and T2DM interactions coming from animal studies and family-based intervention studies. Moreover, many case-control, cohort, cross-sectional cohort studies and clinical trials have identified relationships between individual genetic load, diet and T2DM. Some of these studies were on a large scale. In addition, studies with animal models and human observational studies, in different countries over periods of time, support a causative relationship between adverse nutritional conditions during in utero development, persistent epigenetic changes and T2DM. This review provides comprehensive information on the current state of nutrient-gene interactions and their role in T2DM pathogenesis, the relationship between individual genetic load and diet, and the importance of epigenetic factors in influencing gene expression and defining the individual risk of T2DM.

The intracellular chloride channel proteins CLIC1 and CLIC4 induce IL-1β transcription and activate the NLRP3 inflammasome

The NLRP3 inflammasome is a multiprotein complex that regulates the activation of caspase-1 leading to the maturation of the proinflammatory cytokines IL-1β and IL-18 and promoting pyroptosis. Classically, the NLRP3 inflammasome in murine macrophages is activated by the recognition of pathogen-associated molecular patterns and by many structurally unrelated factors. Understanding the precise mechanism of NLRP3 activation by such a wide array of stimuli remains elusive, but several signaling events, including cytosolic efflux and influx of select ions, have been suggested. Accordingly, several studies have indicated a role of anion channels in NLRP3 inflammasome assembly, but their direct involvement has not been shown. Here, we report that the chloride intracellular channel proteins CLIC1 and CLIC4 participate in the regulation of the NLRP3 inflammasome. Confocal microscopy and cell fractionation experiments revealed that upon LPS stimulation of macrophages, CLIC1 and CLIC4 translocated into the nucleus and cellular membrane. In LPS/ATP-stimulated bone marrow-derived macrophages (BMDMs), CLIC1 or CLIC4 siRNA transfection impaired transcription of IL-1β, ASC speck formation, and secretion of mature IL-1β. Collectively, our results demonstrate that CLIC1 and CLIC4 participate both in the priming signal for IL-1β and in NLRP3 activation.

n-3 Fatty acids modulate the mRNA expression of the Nlrp3 inflammasome and Mtor in the liver of rats fed with high-fat or high-fat/fructose diets

CONTEXT

There is evidence that n-3 polyunsaturated fatty acids (n-3-PUFAs) can inhibit mTORC1, which should potentiate autophagy and eliminate NLRP3 inflammasome activity.

OBJECTIVE

Evaluate the effect of a high-fat or high-fat/fructose diet with and without n-3-PUFAs on hepatic gene expression.

MATERIALS AND METHODS

We examined the mRNA expression by RT-PCR of Mtor, Nlrp3, and other 22 genes associated with inflammation in rats livers after a 9-week diet. The dietary regimens were low-fat (control, CD), high-fat (HF), high-fat/fructose (HF-Fr), and also each of these supplemented with n-3-PUFAs (CD-n-3-PUFAs, HF-n-3-PUFAs, and HF-Fr-n-3-PUFAs). These data were processed by GeneMania and STRING databases.

RESULTS

Compared to the control, the HF group showed a significant increase (between p < 0.05 and p < 0.0001) in 20 of these genes (Il1b, Il18, Rxra, Nlrp3, Casp1, Il33, Tnf, Acaca, Mtor, Eif2s1, Eif2ak4, Nfkb1, Srebf1, Hif1a, Ppara, Ppard, Pparg, Mlxipl, Fasn y Scd1), and a decrease in Sirt1 (p < 0.05). With the HF-Fr diet, a significant increase (between p < 0.05 and p < 0.005) was also found in the expression of 16 evaluated genes (Srebf1, Mlxipl, Rxra, Abca1, Il33, Nfkb1, Hif1a, Pparg, Casp1, Il1b, Il-18, Tnf, Ppard, Acaca, Fasn, Scd1), along with a decrease in the transcription of Mtor and Elovl6 (p < 0.05). Contrarily, many of the genes whose expression increased with the HF and HF-Fr diets did not significantly increase with the HF-n-3-PUFAs or HF-Fr-n-3-PUFAs diet.

DISCUSSION AND CONCLUSION

We found the interrelation of the genes for the mTORC1 complex, the NLRP3 inflammasome, and other metabolically important proteins, and that these genes respond to n-3-PUFAs.

Therapeutically Targeting the Inflammasome Product in a Chimeric Model of Endometriosis-Related Surgical Adhesions

Development of adhesions commonly occurs in association with surgery for endometriosis. Even in the absence of surgery, women with endometriosis appear to be at an enhanced risk of developing adhesions. In the current study, we utilized a chimeric mouse model of experimental endometriosis in order to examine the role of inflammasome activation in the development of postsurgical adhesions. Mice were randomized to receive peritoneal injections of human endometrial tissue fragments or endometrial tissue conditioned media (CM) from women with or without endometriosis 16 hours after ovariectomy and placement of an estradiol-releasing silastic capsule. A subset of mice receiving CM was also treated with interleukin (IL) 1 receptor antagonist (IL-1ra). Our studies demonstrate that peritoneal injection of endometrial tissue fragments near the time of surgery resulted in extensive adhesive disease regardless of tissue origin. However, adhesion scores were significantly higher in mice receiving CM from tissues acquired from patients with endometriosis compared to control tissue CM ( P = .0001). Cytokine bead array analysis of endometrial CM revealed enhanced expression of IL-1β from patients with endometriosis compared to controls ( P < .01). Finally, the ability of human tissue CM to promote adhesive disease was dramatically reduced in mice cotreated with IL-1ra ( P < .0001). Our data implicate enhanced expression of IL-1β in women with endometriosis as a potential causal factor in their increased susceptibility of developing postsurgical adhesions. Thus, targeting inflammasome activation may be an effective strategy for the prevention of surgical adhesions in patients with endometriosis.

Alterations of specific lipid groups in serum of obese humans: a review

Obesity is a major contributor to the dysfunction of liver, cardiac, pulmonary, endocrine and reproductive system, as well as a component of metabolic syndrome. Although development of obesity-related disorders is associated with lipid abnormalities, most previous studies dealing with the problem in question were limited to routinely determined parameters, such as serum concentrations of triacylglycerols, total cholesterol, low-density and high-density lipoprotein cholesterol. Many authors postulated to extend the scope of analysed lipid compounds and to study obesity-related alterations in other, previously non-examined groups of lipids. Comprehensive quantitative, structural and functional analysis of specific lipid groups may result in identification of new obesity-related alterations. The review summarizes available evidence of obesity-related alterations in various groups of lipids and their impact on health status of obese subjects. Further, the role of diet and endogenous lipid synthesis in the development of serum lipid alterations is discussed, along with potential application of various lipid compounds as risk markers for obesity-related comorbidities.

Elimination of the unnecessary: Intra- and extracellular signaling by anionic phospholipids

High fidelity of biological systems is frequently achieved by duplication of the essential intracellular machineries or, removal of the entire cell, which becomes unnecessary or even harmful in altered physiological environments. Carefully controlled removal of these cells, without damaging normal cells, requires precise signaling, and is critical to maintaining homeostasis. This review describes how two anionic phospholipids - phosphatidylserine (PS) and cardiolipin (CL) - residing in distinct compartments of the cell, signal removal of "the unnecessary" using several uniform principles. One of these principles is realized by collapse of inherent transmembrane asymmetry and the externalization of the signal on the outer membrane surface - mitochondria for CL and the plasma membrane for PS - to trigger mitophagy and phagocytosis, respectively. Release from damaged cells of intracellular structures with externalized CL or externalized PS triggers their elimination by phagocytosis. Another of these principles is realized by oxidation of polyunsaturated species of CL and PS. Highly specific oxidation of CL by cytochrome c serves as a signal for mitochondria-dependent apoptosis, while oxidation of externalized PS improves its effectiveness to trigger phagocytosis of effete cells.

The SGLT-2 Inhibitor Dapagliflozin Has a Therapeutic Effect on Atherosclerosis in Diabetic ApoE-/- Mice

Background. Our study aimed to observe the effect of sodium glucose cotransporter-2 (SGLT2) inhibitor dapagliflozin on diabetic atherosclerosis and investigate the subsequent mechanism. Methods. Aortic atherosclerosis was induced in streptozotocin induced diabetic ApoE-/- mice by feeding with high-fat diet, and dapagliflozin was administrated intragastrically for 12 weeks as treatment. Effects of dapagliflozin on indices of glucose and fat metabolism, IL-1β, IL-18, NLRP3 protein levels, and the reactive oxygen species (ROS) were measured. The atherosclerosis was evaluated by oil red O and hematoxylin-eosin staining. The effects of dapagliflozin on the IL-1β production in culturing primary macrophages of wild type and NLRP3-/- knockout mice were investigated for mechanism analyses. Results. Dapagliflozin treatment showed favorable effects on glucose and fat metabolism, partially reversed the formation of atherosclerosis, inhibited macrophage infiltration, and enhanced the stability of lesion. Also, reduced production of IL-1β, IL-18, NLRP3 protein, and mitochondrial ROS in the aortic tissues was detected with dapagliflozin treatment. In vitro, NLRP3 inflammasome was activated by hyperglucose and hyperlipid through ROS pathway. Conclusions. Dapagliflozin may be of therapeutic potential for diabetic atherosclerosis induced by high-fat diet, and these benefits may depend on the inhibitory effect on the secretion of IL-1β by macrophages via the ROS-NLRP3-caspase-1 pathway.

Pleurotus nebrodensis polysaccharide(PN50G) evokes A549 cell apoptosis by the ROS/AMPK/PI3K/AKT/mTOR pathway to suppress tumor growth

Since the strong antineoplastic potential against A549 cells of Pleurotus nebrodensis polysaccharide (PN50G) in vitro has been proven previously, the definitive mechanism of PN50G-induced apoptosis in A549 cells in vivo was further investigated. All the results indicated that PN50G significantly suppressed tumor growth in A549 tumor-bearing mice. Tumor cells treated with PN50G were arrested in the G0/G1 phase, and marked changes in the expression of cell cycle-related proteins, including cyclin D1, cyclin A and cyclin B1, were observed. Moreover, western blotting analysis indicated that PN50G triggered the mitochondrial apoptotic pathway, for an increased Bax/Bcl-2 ratio, release of cytochrome c, cleavage of caspase-3 and PRPP in A549 tumor cells were observed. And the decrease in the expression of the translation related protein P70S6K was observed, because PN50G activated AMPK phosphorylation, but inhibited PI3K/AKT phosphorylation and suppressed the activation of the mammalian target of rapamycin (mTOR) induced by PN50G. In vivo imaging was performed on tumor-bearing mice, and the results indicated that PN50G significantly increased the intracellular levels of reactive oxygen species (ROS). Furthermore, it indicated that PN50G promoted the protein expression of Beclin 1 and LC-3 in a dose-dependent manner. All the results suggested that PN50G-mediated apoptosis and autophagy of A549 tumor cells in vivo mainly involved in the mitochondrial pathway and the AMPK/PI3K/mTOR pathway.

Pathophysiology of Non Alcoholic Fatty Liver Disease

The physiopathology of fatty liver and metabolic syndrome are influenced by diet, life style and inflammation, which have a major impact on the severity of the clinicopathologic outcome of non-alcoholic fatty liver disease. A short comprehensive review is provided on current knowledge of the pathophysiological interplay among major circulating effectors/mediators of fatty liver, such as circulating lipids, mediators released by adipose, muscle and liver tissues and pancreatic and gut hormones in relation to diet, exercise and inflammation.

Probenecid protects against oxygen-glucose deprivation injury in primary astrocytes by regulating inflammasome activity

Inflammation is extremely important in the development of cerebral ischemia/reperfusion injury. Pannexin 1 (Panx1) channel has been reported to activate inflammasome in astrocytes and be involved in ischemic injury, but this damage effect is reversed by a Panx1 inhibitor-probenecid. However, the mechanism of probenecid protects against cerebral ischemia/reperfusion injury remains unclear. In present study, we hypothesized that probenecid protected astrocytes from ischemia/reperfusion injury in vitro by modulating the inflammasome. Primary cultured neocortical astrocytes were exposed to oxygen-glucose deprivation/reoxygenation (OGD/RX) and probenecid was added in this model. Viability and nuclear morphology of astrocytes, production of reactive oxygen species (ROS), protein expressions of NLRP3 (NOD-like receptor protein 3), caspase-1, and AQP4 (Aquaporins 4), as well as release of cellular HMGB1 and IL-1β were observed to evaluate the effect and mechanisms of probenecid on OGD/reoxygenated astrocytes. Probenecid did not affect cell viability at concentrations of 1, 5, 10, and 100μM but induced significant astrocytes death at 500μM. Probenecid inhibited cell death and ROS generation in astrocytes subjected to 6h of OGD and 24h of reoxygenation. The expression levels of NLRP3, caspase-1, and AQP4 increased after 6h of OGD, but probenecid treatment attenuated this increase. Moreover, the extracellular release of IL-1β and HMGB1 from OGD/reoxygenated astrocytes increased significantly. However, treatment by probenecid resulted in substantial reduction of these proteins levels in extracellular space. In conclusion, The Panx1 inhibitor, probenecid, which was administered before OGD, provided protective effects on the OGD/reoxygenation model of cultured astrocytes by modulating inflammasome activity and downregulating AQP4 expression.

Colchicine to decrease NLRP3-activated inflammation and improve obesity-related metabolic dysregulation

Obesity is a major risk-factor for the development of insulin resistance, type 2 diabetes, and cardiovascular disease. Circulating molecules associated with obesity, such as saturated fatty acids and cholesterol crystals, stimulate the innate immune system to incite a chronic inflammatory state. Studies in mouse models suggest that suppressing the obesity-induced chronic inflammatory state may prevent or reverse obesity-associated metabolic dysregulation. Human studies, however, have been far less positive, possibly because targeted interventions were too far downstream of the inciting inflammatory events. Recently, it has been shown that, within adipose tissue macrophages, assembly of a multi-protein member of the innate immune system, the NOD-like receptor family pyrin domain containing 3 (NLRP3) inflammasome, is essential for the induction of this inflammatory state. Microtubules enable the necessary spatial arrangement of the components of the NLRP3 inflammasome in the cell, leading to its activation and propagation of the inflammatory cascade. Colchicine, a medication classically used for gout, mediates its anti-inflammatory effect by inhibiting tubulin polymerization, and has been shown to attenuate macrophage NLRP3 inflammasome arrangement and activation in vitro and in vivo. Given these findings, we hypothesize that, in at-risk individuals (those with obesity-induced inflammation and metabolic dysregulation), long-term colchicine use will lead to suppression of inflammation and thus cause improvements in insulin sensitivity and other obesity-related metabolic impairments.

Protective mechanisms of wogonoside against Lipopolysaccharide/D-galactosamine-induced acute liver injury in mice

Wogonoside, a bioactive flavonoid extracted from the root of Scutellaria baicalensis Georgi, has been reported to have anti-inflammatory and antioxidant effects. In this study, we examined the protective effects of wogonoside against lipopolysaccharide (LPS) and D-galactosamine (D-GalN)-induced liver injury in mice. Mice were given an intraperitoneal injection of wogonoside 1h before LPS and d-GalN treatment. The results showed that wogonoside inhibited the production of serum Alanine transaminase (ALT), Aspartate aminotransferase (AST), IL-1β, TNF-α, and hepatic malondialdehyde (MDA) content induced by LPS/GalN. In addition, wogonoside promoted the expression of Nrf2, NQO-1, GCLC, and HO-1. Wogonoside inhibited the expression of hepatic NLRP3, ASC, caspase-1, and IL-1β induced by LPS/GalN. In conclusion, these results suggest that wogonoside protects against LPS/GalN-induced acute liver injury by activating Nrf2 and inhibiting NLRP3 inflammasome activation.

Bypassing Mechanisms of Mitochondria-Mediated Cancer Stem Cells Resistance to Chemo- and Radiotherapy

Cancer stem cells (CSCs) are highly resistant to conventional chemo- and radiotherapeutic regimes. Therefore, the multiple drug resistance (MDR) of cancer is most likely due to the resistance of CSCs. Such resistance can be attributed to some bypassing pathways including detoxification mechanisms of reactive oxygen and nitrogen species (RO/NS) formation or enhanced autophagy. Unlike in normal cells, where RO/NS concentration is maintained at certain threshold required for signal transduction or immune response mechanisms, CSCs may develop alternative pathways to diminish RO/NS levels leading to cancer survival. In this minireview, we will focus on elaborated mechanisms developed by CSCs to attenuate high RO/NS levels. Gaining a better insight into the mechanisms of stem cell resistance to chemo- or radiotherapy may lead to new therapeutic targets thus serving for better anticancer strategies.

NLRP3 inflammasome and its inhibitors: a review

Inflammasomes are newly recognized, vital players in innate immunity. The best characterized is the NLRP3 inflammasome, so-called because the NLRP3 protein in the complex belongs to the family of nucleotide-binding and oligomerization domain-like receptors (NLRs) and is also known as “pyrin domain-containing protein 3”. The NLRP3 inflammasome is associated with onset and progression of various diseases, including metabolic disorders, multiple sclerosis, inflammatory bowel disease, cryopyrin-associated periodic fever syndrome, as well as other auto-immune and auto-inflammatory diseases. Several NLRP3 inflammasome inhibitors have been described, some of which show promise in the clinic. The present review will describe the structure and mechanisms of activation of the NLRP3 inflammasome, its association with various auto-immune and auto-inflammatory diseases, and the state of research into NLRP3 inflammasome inhibitors.

Linking diet to acne metabolomics, inflammation, and comedogenesis: an update

Acne vulgaris, an epidemic inflammatory skin disease of adolescence, is closely related to Western diet. Three major food classes that promote acne are: 1) hyperglycemic carbohydrates, 2) milk and dairy products, 3) saturated fats including trans-fats and deficient ω-3 polyunsaturated fatty acids (PUFAs). Diet-induced insulin/insulin-like growth factor (IGF-1)-signaling is superimposed on elevated IGF-1 levels during puberty, thereby unmasking the impact of aberrant nutrigenomics on sebaceous gland homeostasis. Western diet provides abundant branched-chain amino acids (BCAAs), glutamine, and palmitic acid. Insulin and IGF-1 suppress the activity of the metabolic transcription factor forkhead box O1 (FoxO1). Insulin, IGF-1, BCAAs, glutamine, and palmitate activate the nutrient-sensitive kinase mechanistic target of rapamycin complex 1 (mTORC1), the key regulator of anabolism and lipogenesis. FoxO1 is a negative coregulator of androgen receptor, peroxisome proliferator-activated receptor-γ (PPARγ), liver X receptor-α, and sterol response element binding protein-1c (SREBP-1c), crucial transcription factors of sebaceous lipogenesis. mTORC1 stimulates the expression of PPARγ and SREBP-1c, promoting sebum production. SREBP-1c upregulates stearoyl-CoA- and Δ6-desaturase, enhancing the proportion of monounsaturated fatty acids in sebum triglycerides. Diet-mediated aberrations in sebum quantity (hyperseborrhea) and composition (dysseborrhea) promote Propionibacterium acnes overgrowth and biofilm formation with overexpression of the virulence factor triglyceride lipase increasing follicular levels of free palmitate and oleate. Free palmitate functions as a "danger signal," stimulating toll-like receptor-2-mediated inflammasome activation with interleukin-1β release, Th17 differentiation, and interleukin-17-mediated keratinocyte proliferation. Oleate stimulates P. acnes adhesion, keratinocyte proliferation, and comedogenesis via interleukin-1α release. Thus, diet-induced metabolomic alterations promote the visible sebofollicular inflammasomopathy acne vulgaris. Nutrition therapy of acne has to increase FoxO1 and to attenuate mTORC1/SREBP-1c signaling. Patients should balance total calorie uptake and restrict refined carbohydrates, milk, dairy protein supplements, saturated fats, and trans-fats. A paleolithic-like diet enriched in vegetables and fish is recommended. Plant-derived mTORC1 inhibitors and ω-3-PUFAs are promising dietary supplements supporting nutrition therapy of acne vulgaris.

Inflammasomes: mechanism of action, role in disease, and therapeutics

The inflammasomes are innate immune system receptors and sensors that regulate the activation of caspase-1 and induce inflammation in response to infectious microbes and molecules derived from host proteins. They have been implicated in a host of inflammatory disorders. Recent developments have greatly enhanced our understanding of the molecular mechanisms by which different inflammasomes are activated. Additionally, increasing evidence in mouse models, supported by human data, strongly implicates an involvement of the inflammasome in the initiation or progression of diseases with a high impact on public health, such as metabolic disorders and neurodegenerative diseases. Finally, recent developments pointing toward promising therapeutics that target inflammasome activity in inflammatory diseases have been reported. This review will focus on these three areas of inflammasome research.

Inflammatory markers and cardiometabolic diseases

OBJECTIVES

A growing body of evidence emerges that obesity, metabolic syndrome, type 2 diabetes and cardiovascular disease are intimately related to chronic inflammation.

METHODS

A narrative review summarizing the most recent data of the literature describing the pathological implications of inflammation in obese patients with cardiometabolic disorders.

RESULTS

Besides high-sensitive C-reactive protein, various circulating or in situ inflammatory markers have been identified, presumably reflecting the presence of inflammation in various key-organs (visceral adipose tissue, skeletal muscle, pancreatic islets, liver, intestine, arterial wall). Available data support the concept that targeting inflammation, not only reduces systemic inflammatory markers, but also improves insulin sensitivity and ameliorates glucose control in insulin-resistant patients, thus potentially reducing the risk of cardiovascular complications.

CONCLUSION

These observations confirm the role of inflammation in cardiometabolic diseases and support the development of pharmacological strategies that aim at reducing inflammation, especially in patients with type 2 diabetes.

Functions of omega-3 fatty acids and FFA4 (GPR120) in macrophages

Omega-3 polyunsaturated fatty acids (n-3 PUFAs), which are plentiful in fish oil, have been known for decades to be beneficial functional nutrients in different disease states. GPR120 is a G protein-coupled receptor for long-chain unsaturated fatty acids, including n-3 PUFAs, and was recently renamed free fatty acid receptor 4 (FFA4). Studies on FFA4-deficient mice and the development of specific pharmacological tools have started to unravel the functions of FFA4 associated with the actions of n-3 PUFAs in obesity, type 2 diabetes, and inflammation-related diseases. Here, the state of the art regarding the roles and functions of FFA4 and n-3 PUFA in macrophages are reviewed from the pharmacological perspective. In particular, the functions of n-3 PUFA on the anti-inflammatory M2 phenotypes of macrophages in different organs, such as, adipose tissues and liver, are discussed along with future research directions.

A pilot study of ezetimibe vs. atorvastatin for improving peripheral microvascular endothelial function in stable patients with type 2 diabetes mellitus

BACKGROUND

Elevated cholesterol in type 2 diabetes mellitus (DM) can cause endothelial dysfunction. An effective clinical therapy to improve endothelial dysfunction remains to be established. Different cardiovascular actions between treatments for the inhibition of cholesterol absorption and the suppression of cholesterol synthesis for achieving improvement in endothelial function are unknown in DM.

METHODS

Stable patients with type 2 DM and mildly elevated low-density lipoprotein cholesterol were enrolled. We evaluated peripheral microvascular endothelial function using reactive hyperemia peripheral arterial tonometry (RH-PAT) examination and calculated a natural logarithmic transformed value for the RH-PAT index (LnRHI). We randomly assigned 33 patients to each monotherapy: cholesterol synthesis suppression using atorvastatin (5 mg/day, n=16) or cholesterol absorption inhibition using ezetimibe (10 mg/day, n=17). Patients were prospectively followed for 6 months. Serum lipids and LnRHI were repeatedly examined before and after each therapy.

RESULTS

LDL significantly decreased in both groups, but the percent changes of LDL showed a greater decrease in the atorvastatin group compared with the ezetimibe group (-34.5±7.8% vs. -21.9±9.6%, p<0.01). Serum levels of non-esterified free fatty acids (NEFA) significantly decreased in the ezetimibe group but not in the atorvastatin group (ezetimibe group: 561.1±236.8 to 429.7±195.9, p<0.01; atorvastatin group: 538.8±319.5 to 520.2±227.3, p=0.75). The percent decrease in NEFA was significantly greater in the ezetimibe group compared with the atorvastatin group (-19.9±27.4% vs. 11.3±44.1%, p<0.05). LnRHI showed a significant increase in the ezetimibe group but not in the atorvastatin group (ezetimibe group: 0.471±0.157 to 0.678±0.187, p<0.01; atorvastatin group: 0.552±0.084 to 0.558±0.202, p=0.64). The percent changes in LnRHI were significantly greater in the ezetimibe group compared with the atorvastatin group (63.3±89.2% vs. 7.4±41.2%, p<0.05).

CONCLUSIONS

In patients with type 2 DM, ezetimibe monotherapy significantly reduced LDL and NEFA, and improved peripheral microvascular endothelial dysfunction. Ezetimibe could potentially exhibit beneficial effects on lipid disorders and microvascular endothelial dysfunction in DM.

Clinical Review: Familial Mediterranean Fever-An Overview of Pathogenesis, Symptoms, Ocular Manifestations, and Treatment

Familial Mediterranean fever is an autoinflammatory multisystem disease, which most commonly affects patients from the Mediterranean basin. This review discusses the common polymorphisms in the MEFV gene as well as the role of pyrin in disease pathogenesis. Patients with familial Mediterranean fever typically develop peritonitis, pleuritis, arthritis, and fever. In addition, a number of authors have reported ophthalmic features. These case reports and series are further explored in this review. Colchicine has transformed the prognosis for patients with familial Mediterranean fever. The rationale for the use of colchicine, as well as the evidence for newer biologic agents is also covered.

Healing rate and autoimmune safety of full-thickness wounds treated with fish skin acellular dermal matrix versus porcine small-intestine submucosa: a noninferiority study

A novel product, the fish skin acellular dermal matrix (ADM) has recently been introduced into the family of biological materials for the treatment of wounds. Hitherto, these products have been produced from the organs of livestock. A noninferiority test was used to compare the effect of fish skin ADM against porcine small-intestine submucosa extracellular matrix in the healing of 162 full-thickness 4-mm wounds on the forearm of 81 volunteers. The fish skin product was noninferior at the primary end point, healing at 28 days. Furthermore, the wounds treated with fish skin acellular matrix healed significantly faster. These results might give the fish skin ADM an advantage because of its environmental neutrality when compared with livestock-derived products. The study results on these acute full-thickness wounds might apply for diabetic foot ulcers and other chronic full-thickness wounds, and the shorter healing time for the fish skin-treated group could influence treatment decisions. To test the autoimmune reactivity of the fish skin, the participants were tested with the following ELISA (enzyme-linked immunosorbent assay) tests: RF, ANA, ENA, anti ds-DNA, ANCA, anti-CCP, and anticollagen I and II. These showed no reactivity. The results demonstrate the claims of safety and efficacy of fish skin ADM for wound care.

Fatty acid signaling: the new function of intracellular lipases

Until recently, intracellular triacylglycerols (TAG) stored in the form of cytoplasmic lipid droplets have been considered to be only passive “energy conserves”. Nevertheless, degradation of TAG gives rise to a pleiotropic spectrum of bioactive intermediates, which may function as potent co-factors of transcription factors or enzymes and contribute to the regulation of numerous cellular processes. From this point of view, the process of lipolysis not only provides energy-rich equivalents but also acquires a new regulatory function. In this review, we will concentrate on the role that fatty acids liberated from intracellular TAG stores play as signaling molecules. The first part provides an overview of the transcription factors, which are regulated by fatty acids derived from intracellular stores. The second part is devoted to the role of fatty acid signaling in different organs/tissues. The specific contribution of free fatty acids released by particular lipases, hormone-sensitive lipase, adipose triacylglycerol lipase and lysosomal lipase will also be discussed.