Plant miR8126-3p and miR8126-5p Decrease Lipid Accumulation through Modulation of Metabolic Genes in a Human Hepatocyte Model That Mimics Steatosis.

Plant-based food interventions are promising therapeutic approaches for non-alcoholic fatty liver disease (NAFLD) treatment, and microRNAs (miRNAs) have emerged as functional bioactive components of dietary plants involved in cross-kingdom communication. Deeper investigations are needed to determine the potential impact of plant miRNAs in NAFLD. This study aimed to identify plant miRNAs that could eventually modulate the expression of human metabolic genes and protect against the progression of hepatic steatosis. Plant miRNAs from the miRBase were used to predict human target genes, and miR8126-3p and miR8126-5p were selected as candidates for their potential role in inhibiting glucose and lipid metabolism-related genes. Human HepG2 cells were transfected with plant miRNA mimics and then exposed to a mixture of oleic and palmitic acids to mimic steatosis. miR8126-3p and miR8126-5p transfections inhibited the expression of the putative target genes QKI and MAPKAPK2, respectively, and had an impact on the expression profile of key metabolic genes, including PPARA and SREBF1. Quantification of intrahepatic triglycerides revealed that miR8126-3p and miR8126-5p attenuated lipid accumulation. These findings suggest that plant miR8126-3p and miR8126-5p would induce metabolic changes in human hepatocytes eventually protecting against lipid accumulation, and thus, they could be potential therapeutic tools for preventing and alleviating lipid accumulation.

CRISPR/Cas9-mediated deletion of adipocyte genes associated with NAFLD alters adipocyte lipid handling and reduces steatosis in hepatocytes in vitro.

Obesity is a major risk factor for the development of nonalcoholic fatty liver disease (NAFLD), and the subcutaneous white adipose tissue (scWAT) is the primary lipid storage depot and regulates lipid fluxes to other organs. Our previous work identified genes upregulated in scWAT of patients with NAFLD: SOCS3, DUSP1, and SIK1. Herein, we knocked down (KD) their expression in human adipose-derived mesenchymal stem cells (hADMSCs) using clustered regularly interspaced short palindromic repeats (CRISPR)/Cas9 technology and characterized their phenotype. We found that SOCS3, DUSP1, and SIK1 expression in hADMSC-derived adipocytes was not critical for adipogenesis. However, the metabolic characterization of the cells suggested that the genes played important roles in lipid metabolism. Reduction of SIK1 expression significantly increased both de novo lipogenesis (DNL) and palmitate-induced lipogenesis (PIL). Editing out SOCS3 reduced DNL while increasing isoproterenol-induced lipolysis and insulin-induced palmitate accumulation. Conversely, DUSP1 reduced PIL and DNL. Moreover, RNA-sequencing analysis of edited cells showed that these genes not only altered lipid metabolism but also other biological pathways related to inflammatory processes, in the case of DUSP1, extracellular matrix remodeling for SOCS3, or cellular transport for SIK1. Finally, to evaluate a possible adipocyte-hepatocyte axis, human hepatoma HepG2 cells were cocultured with edited hADMSCs-derived adipocytes in the presence of [3H]-palmitate. All HepG2 cells cultured with DUSP1-, SIK1-, or SOCS3-KD adipocytes decreased [3H]-palmitate accumulation compared with control adipocytes. These results support our hypotheses that SOCS3, DUSP1, and SIK1 regulate multiple aspects of adipocyte function, which may play a role in the progression of obesity-associated comorbidities, such as NAFLD.NEW & NOTEWORTHY Clustered regularly interspaced short palindromic repeats (CRISPR)/Cas9 technology successfully edited genomic DNA of human adipose-derived mesenchymal stem cells (hADMSC). SOCS3, SIK1, and DUSP1 regulate adipocyte lipid handling. Silencing SOCS3, SIK1, and DUSP1 expression in hADMSC-derived adipocytes reduces hepatocyte lipid storage in vitro.

Isthmin-1 (ISM1), a novel adipokine that reflects abdominal adipose tissue distribution in individuals with obesity.

BACKGROUND: The assessment of obesity-related health risks has traditionally relied on the Body Mass Index and waist circumference, but their limitations have propelled the need for a more comprehensive approach. The differentiation between visceral (VIS) and subcutaneous (SC) fat provides a finer-grained understanding of these risks, yet practical assessment methods are lacking. We hypothesized that combining the SC-VIS fat ratio with non-invasive biomarkers could create a valuable tool for obesity-related risk assessment. METHODS AND RESULTS: A clinical study of 125 individuals with obesity revealed significant differences in abdominal fat distribution measured by CT-scan among genders and distinct models of obesity, including visceral, subcutaneous, and the SC/VIS ratio. Stratification based on these models highlighted various metabolic changes. The SC/VIS ratio emerged as an excellent metric to differentiate metabolic status. Gene expression analysis identified candidate biomarkers, with ISM1 showing promise. Subsequent validation demonstrated a correlation between ISM1 levels in SC and plasma, reinforcing its potential as a non-invasive biomarker for fat distribution. Serum adipokine levels also correlated with the SC/VIS ratio. The Receiver Operating Characteristic analysis revealed ISM1's efficacy in discriminating individuals with favorable metabolic profiles based on adipose tissue distribution. Correlation analysis also suggested that ISM1 was involved in glucose regulation pathways. CONCLUSION: The study's results support the hypothesis that the SC-VIS fat ratio and its derived non-invasive biomarkers can comprehensively assess obesity-related health risks. ISM1 could predict abdominal fat partitioning and be a potential biomarker for evaluating obesity-related health risks.

Identification of novel targets in adipose tissue involved in non-alcoholic fatty liver disease progression.

Obesity is a major risk factor for the development of Nonalcoholic fatty liver disease (NAFLD). We hypothesize that a dysfunctional subcutaneous white adipose tissue (scWAT) may lead to an accumulation of ectopic fat in the liver. Our aim was to investigate the molecular mechanisms involved in the causative role of scWAT in NALFD progression. We performed a RNA-sequencing analysis in a discovery cohort (n = 45) to identify genes in scWAT correlated with fatty liver index, a qualitative marker of liver steatosis. We then validated those targets in a second cohort (n = 47) of obese patients who had liver biopsies available. Finally, we obtained scWAT mesenchymal stem cells (MSCs) from 13 obese patients at different stages of NAFLD and established in vitro models of human MSC (hMSC)-derived adipocytes. We observed impaired adipogenesis in hMSC-derived adipocytes as liver steatosis increased, suggesting that an impaired adipogenic capacity is a critical event in the development of NAFLD. Four genes showed a differential expression pattern in both scWAT and hMSC-derived adipocytes, where their expression paralleled steatosis degree: SOCS3, DUSP1, SIK1, and GADD45B. We propose these genes as key players in NAFLD progression. They could eventually constitute potential new targets for future therapies against liver steatosis.

MicroRNAs and other non-coding RNAs in adipose tissue and obesity: emerging roles as biomarkers and therapeutic targets.

Obesity is a metabolic condition usually accompanied by insulin resistance (IR), type 2 diabetes (T2D), and dyslipidaemia, which is characterised by excessive fat accumulation and related to white adipose tissue (WAT) dysfunction. Enlargement of WAT is associated with a transcriptional alteration of coding and non-coding RNAs (ncRNAs). For many years, big efforts have focused on understanding protein-coding RNAs and their involvement in the regulation of adipocyte physiology and subsequent role in obesity. However, diverse findings have suggested that a dysfunctional adipocyte phenotype in obesity might be also dependent on specific alterations in the expression pattern of ncRNAs, such as miRNAs. The aim of this review is to update current knowledge on the physiological roles of miRNAs and other ncRNAs in adipose tissue function and their potential impact on obesity. Therefore, we examined their regulatory role on specific WAT features: adipogenesis, adipokine secretion, inflammation, glucose metabolism, lipolysis, lipogenesis, hypoxia and WAT browning. MiRNAs can be released to body fluids and can be transported (free or inside microvesicles) to other organs, where they might trigger metabolic effects in distant tissues, thus opening new possibilities to a potential use of miRNAs as biomarkers for diagnosis, prognosis, and personalisation of obesity treatment. Understanding the role of miRNAs also opens the possibility of using these molecules on individualised dietary strategies for precision weight management. MiRNAs should be envisaged as a future therapeutic approach given that miRNA levels could be modulated by synthetic molecules (f.i. miRNA mimics and inhibitors) and/or specific nutrients or bioactive compounds.

miRNAs and Novel Food Compounds Related to the Browning Process.

Obesity prevalence is rapidly increasing worldwide. With the discovery of brown adipose tissue (BAT) in adult humans, BAT activation has emerged as a potential strategy for increasing energy expenditure. Recently, the presence of a third type of fat, referred to as beige or brite (brown in white), has been recognized to be present in certain kinds of white adipose tissue (WAT) depots. It has been suggested that WAT can undergo the process of browning in response to stimuli that induce and enhance the expression of thermogenesis: a metabolic feature typically associated with BAT. MicroRNAs (miRNAs) are small transcriptional regulators that control gene expression in a variety of tissues, including WAT and BAT. Likewise, it was shown that several food compounds could influence miRNAs associated with browning, thus, potentially contributing to the management of excessive adipose tissue accumulation (obesity) through specific nutritional and dietetic approaches. Therefore, this has created significant excitement towards the development of a promising dietary strategy to promote browning/beiging in WAT to potentially contribute to combat the growing epidemic of obesity. For this reason, we summarize the current knowledge about miRNAs and food compounds that could be applied in promoting adipose browning, as well as the cellular mechanisms involved.

Inflammation stimulates hypoxia-inducible factor-1α regulatory activity in 3T3-L1 adipocytes with conditioned medium from lipopolysaccharide-activated RAW 264.7 macrophages.

Obesity is a multifactorial, chronic, inflammatory disease that involves different processes, such as adipose tissue hypoxia. The aim of the current study was to characterize the effects of conditioned medium (CM) from lipopolysaccharide (LPS)-activated macrophages on the regulation of hypoxia-inducible factor 1α (HIF-1α)-related genes in murine adipocytes. For the in vitro analyses, 3T3-L1 murine adipocytes (9 days postdifferentiation) were incubated either in CM (25% medium of RAW 264.7 murine macrophages with 24 hr 500 ng/ml LPS), LPS at 500 ng/ml, or hypoxia (Hx; 1% O2 , 94% N2 , 5% CO2 ) for 24 hr. For the in vivo experiments, mice were fed a high-fat diet. Both epididymal white adipose tissue (eWAT) and adipocytes in CM showed upregulation of Glut1, Mcp1, Il10, Tnf, and Il1b. The secretion of IL-6, TNF-α, and MCP-1 was also increased in CM-treated adipocytes. Moreover, increased levels of HIF-1α subunit and nuclear factor kappa B p65 were found after CM treatment, linking Hx, and inflammation. HIF-1α directly bound vascular endothelial growth factor A (Vegfa) and uncoupling protein 2 (Ucp2) genes, up- and downregulating its expression, respectively. Furthermore, the oxygen consumption rate was 30% lower in CM. The siRNA knockdown of mammalian target of rapamycin (Mtor) reversed the induction of HIF-1α found in CM. The macrophage infiltration simulated through CM seems to be a similar environment to an abnormally enlarged eWAT. We have evidenced that HIF-1α plays a regulatory role in the expression of Vegfa and Ucp2 in CM. Finally, the inhibition of the mTOR pathway prevented the HIF-1α activation induced by CM. The involvement of HIF-1α under proinflammatory conditions provides insight into the origins of Hx in obesity.

Maresin 1 inhibits TNF-alpha-induced lipolysis and autophagy in 3T3-L1 adipocytes.

Obesity is associated with high levels of pro-inflammatory cytokines such as tumor necrosis factor-alpha (TNF-α), which promotes inflammation in adipose tissue. The omega-3 PUFAs, and their derived lipid mediators, such as Maresin 1 (MaR1) have anti-inflammatory effects on adipose tissue. This study aimed to analyze if MaR1 may counteract alterations induced by TNF-α on lipolysis and autophagy in mature 3T3-L1 adipocytes. Our data revealed that MaR1 (1-100 nM) inhibited the TNF-α-induced glycerol release after 48 hr, which may be related to MaR1 ability of preventing the decrease in lipid droplet-coating protein perilipin and G0/G1 Switch 2 protein expression. MaR1 also reversed the decrease in total hormone sensitive lipase (total HSL), and the ratio of phosphoHSL at Ser-565/total HSL, while preventing the increased ratio of phosphoHSL at Ser-660/total HSL and phosphorylation of extracellular signal-regulated kinase 1/2 induced by TNF-α. Moreover, MaR1 counteracted the cytokine-induced decrease of p62 protein, a key autophagy indicator, and also prevented the induction of LC3II/LC3I, an important autophagosome formation marker. Current data suggest that MaR1 may ameliorate TNF-α-induced alterations on lipolysis and autophagy in adipocytes. This may also contribute to the beneficial actions of MaR1 on adipose tissue and insulin sensitivity in obesity.

MicroRNA profiling links miR-378 to enhanced adipocyte lipolysis in human cancer cachexia.

Cancer cachexia is associated with pronounced adipose tissue loss due to, at least in part, increased fat cell lipolysis. MicroRNAs (miRNAs) have recently been implicated in controlling several aspects of adipocyte function. To gain insight into the possible impact of miRNAs on adipose lipolysis in cancer cachexia, global miRNA expression was explored in abdominal subcutaneous adipose tissue from gastrointestinal cancer patients with (n = 10) or without (n = 11) cachexia. Effects of miRNA overexpression or inhibition on lipolysis were determined in human in vitro differentiated adipocytes. Out of 116 miRNAs present in adipose tissue, five displayed distinct cachexia-associated expression according to both microarray and RT-qPCR. Four (miR-483-5p/-23a/-744/-99b) were downregulated, whereas one (miR-378) was significantly upregulated in cachexia. Adipose expression of miR-378 associated strongly and positively with catecholamine-stimulated lipolysis in adipocytes. This correlation is most probably causal because overexpression of miR-378 in human adipocytes increased catecholamine-stimulated lipolysis. In addition, inhibition of miR-378 expression attenuated stimulated lipolysis and reduced the expression of LIPE, PLIN1, and PNPLA2, a set of genes encoding key lipolytic regulators. Taken together, increased miR-378 expression could play an etiological role in cancer cachexia-associated adipose tissue loss via effects on adipocyte lipolysis.

MicroRNAs from edible plants reach the human gastrointestinal tract and may act as potential regulators of gene expression.

MicroRNAs (miRNAs) are small single-stranded non-coding RNA molecules that regulate gene expression at the post-transcriptional level. A cross-kingdom regulatory function has been unveiled for plant miRNAs (xenomiRs), which could shape inter-species interactions of plants with other organisms (bacteria and humans) and thus, be key functional molecules of plant-based food in mammals. However, discrepancies regarding the stability and bioavailability of dietary plant miRNAs on the host cast in doubt whether these molecules could have a significant impact on human physiology. The aim of the present study was to identify miRNAs in edible plants and determine their bioavailability on humans after an acute intake of plant-based products. It was found that plant food, including fruits, vegetables and greens, nuts, legumes, and cereals, contains a wide range of miRNAs. XenomiRs miR156e, miR159 and miR162 were detected in great abundance in edible plants and were present among many plant foods, and thus, they were selected as candidates to analyse their bioavailability in humans. These plant miRNAs resisted cooking processes (heat-treatments) and their relative presence increased in faeces after and acute intake of plant-based foods, although they were not detected in serum. Bioinformatic analysis revealed that these miRNAs could potentially target human and bacterial genes involved in processes such as cell signalling and metabolism. In conclusion, edible plants contain miRNAs, such as miR156e, miR159 and miR162, that could resist degradation during cooking and digestion and reach the distal segments of the gastrointestinal tract. Nevertheless, strategies should be developed to improve their absorption to potentially reach host tissues and organs and modulate human physiology.

Allograft inflammatory factor 1 (AIF-1) is a new human adipokine involved in adipose inflammation in obese women.

BACKGROUND: Allograft inflammatory factor 1 (AIF-1) is a putative obesity gene. Our aim was to examine the expression of AIF-1 in human white adipose tissue (WAT) in relation to obesity and metabolic phenotypes in women. METHODS: WAT secretion of AIF-1 was determined in subcutaneous adipose tissue pieces in vitro by ELISA from 5 subjects. mRNA expression of AIF-1 was determined by RT-qPCR in the isolated cell fractions of adipose tissue (n = 5-6 per group), in subcutaneous and visceral WAT pieces from non-obese (n = 12) and obese women (n = 23), and in some subcutaneous WAT also before and after weight reduction (n = 10). Finally, adipose AIF-1 mRNA was related to metabolic phenotypes in 96 subjects with a wide range of BMI. RESULTS: AIF-1 was secreted in a time dependent fashion from WAT. The major source of AIF-1 was WAT resident macrophages. Expression of AIF-1 was similar in visceral and subcutaneous WAT and was two-fold increased in obese women (P < 0.01). AIF-1 mRNA expression levels were normalized after weight reduction (P < 0.01). Expression of AIF-1 was inversely correlated with insulin sensitivity as assessed by insulin tolerance test (KITT), and circulating levels of adiponectin (P = 0.02), and positively correlated with insulin resistance as estimated by HOMA (=0.0042). CONCLUSIONS: AIF-1 is a novel adipokine produced mainly by macrophages within human WAT. Its expression is increased in obese women and associates with unfavourable metabolic phenotypes. AIF-1 may play a paracrine role in the regulation of WAT function through cross-talk between macrophages and other cell types within the adipose tissue.

miR482f and miR482c-5p from edible plant-derived foods inhibit the expression of pro-inflammatory genes in human THP-1 macrophages.

Background: Edible plants can exert anti-inflammatory activities in humans, being potentially useful in the treatment of inflammatory diseases. Plant-derived microRNAs have emerged as cross-kingdom gene expression regulators and could act as bioactive molecules involved in the beneficial effects of some edible plants. We investigated the role of edible plant-derived microRNAs in the modulation of pro-inflammatory human genes. Methods: MicroRNAs from plant-derived foods were identified by next-generation sequencing. MicroRNAs with inflammatory putative targets were selected, after performing in silico analyses. The expression of candidate plant-derived miRNAs was analyzed by qPCR in edible plant-derived foods and their effects were evaluated in THP-1 monocytes differentiated to macrophages. The bioavailability of candidate plant miRNAs in humans was evaluated in feces and serum samples by qPCR. Results: miR482f and miR482c-5p are present in several edible plant-derived foods, such as fruits, vegetables, and cooked legumes and cereals, and fats and oils. Transfections with miR482f and miR482c-5p mimics decreased the gene expression of CLEC7A and NFAM1, and TRL6, respectively, in human THP-1 monocytes differentiated to macrophages, which had an impact on gene expression profile of inflammatory biomarkers. Both microRNAs (miR482f and miR482c-5p) resisted degradation during digestion and were detected in human feces, although not in serum. Conclusion: Our findings suggest that miR482f and miR482c-5p can promote an anti-inflammatory gene expression profile in human macrophages in vitro and their bioavailability in humans can be achieved through diet, but eventually restricted at the gut level.

Maresin 1 activates brown adipose tissue and promotes browning of white adipose tissue in mice.

OBJECTIVE: Maresin 1 (MaR1) is a docosahexaenoic acid-derived proresolving lipid mediator with insulin-sensitizing and anti-steatosis properties. Here, we aim to unravel MaR1 actions on brown adipose tissue (BAT) activation and white adipose tissue (WAT) browning. METHODS: MaR1 actions were tested in cultured murine brown adipocytes and in human mesenchymal stem cells (hMSC)-derived adipocytes. In vivo effects of MaR1 were tested in diet-induced obese (DIO) mice and lean WT and Il6 knockout (Il6-/-) mice. RESULTS: In cultured differentiated murine brown adipocytes, MaR1 reduces the expression of inflammatory genes, while stimulates glucose uptake, fatty acid utilization and oxygen consumption rate, along with the upregulation of mitochondrial mass and genes involved in mitochondrial biogenesis and function and the thermogenic program. In Leucine Rich Repeat Containing G Protein-Coupled Receptor 6 (LGR6)-depleted brown adipocytes using siRNA, the stimulatory effect of MaR1 on thermogenic genes was abrogated. In DIO mice, MaR1 promotes BAT remodeling, characterized by higher expression of genes encoding for master regulators of mitochondrial biogenesis and function and iBAT thermogenic activation, together with increased M2 macrophage markers. In addition, MaR1-treated DIO mice exhibit a better response to cold-induced BAT activation. Moreover, MaR1 induces a beige adipocyte signature in inguinal WAT of DIO mice and in hMSC-derived adipocytes. MaR1 potentiates Il6 expression in brown adipocytes and BAT of cold exposed lean WT mice. Interestingly, the thermogenic properties of MaR1 were abrogated in Il6-/- mice. CONCLUSIONS: These data reveal MaR1 as a novel agent that promotes BAT activation and WAT browning by regulating thermogenic program in adipocytes and M2 polarization of macrophages. Moreover, our data suggest that LGR6 receptor is mediating MaR1 actions on brown adipocytes, and that IL-6 is required for the thermogenic effects of MaR1.

Differential effects of 1α,25-dihydroxycholecalciferol on MCP-1 and adiponectin production in human white adipocytes.

BACKGROUND/AIM: Obesity is characterized by a low-grade inflammation in white adipose tissue (WAT), which promotes insulin resistance. Low serum levels of 1α,25-dihydroxycholecalciferol (DHCC) associate with insulin resistance and higher body mass index although it is unclear whether vitamin D supplementation improves insulin sensitivity. We investigated the effects of DHCC on adipokine gene expression and secretion in adipocytes focusing on two key factors with pro-inflammatory [monocyte chemoattractant protein-1 (MCP-1/CCL2)] and anti-inflammatory [adiponectin (ADIPOQ)] effects. METHODS: Pre-adipocytes were isolated from human subcutaneous WAT and cultured until full differentiation. Differentiated adipocytes were either pre-treated with DHCC (10(-7) M) and subsequently incubated with tumor necrosis factor-α (TNFα, 100 ng/mL) or concomitantly incubated with TNFα/DHCC. MCP1 and adiponectin mRNA expression was measured by RT-PCR and protein release by ELISA. RESULTS: DHCC was not toxic and did not affect adipocyte morphology or the mRNA levels of adipocyte-specific genes. TNFα induced a significant increase in CCL2 mRNA and protein secretion, while DHCC alone reduced CCL2 mRNA expression (~25%, p < 0.05). DHCC attenuated TNFα-induced CCL2 mRNA expression in both pre-incubation (~15%, p < 0.05) and concomitant (~60%, p < 0.01) treatments. TNFα reduced ADIPOQ mRNA (~80%) and secretion (~35%). DHCC alone decreased adiponectin secretion to a similar degree (~35%, p < 0.05). Concomitant treatment with DHCC/TNFα for 48 h had an additive effect, resulting in a pronounced reduction in adiponectin secretion (~70%). CONCLUSIONS: DHCC attenuates MCP-1 and adiponectin production in human adipocytes, thereby reducing the expression of both pro- and anti-inflammatory factors. These effects may explain the difficulties so far in determining the role of DHCC in insulin sensitivity and obesity in humans.

Effects of gut microbiota-derived extracellular vesicles on obesity and diabetes and their potential modulation through diet.

Obesity and diabetes incidence rates are increasing dramatically, reaching pandemic proportions. Therefore, there is an urgent need to unravel the mechanisms underlying their pathophysiology. Of particular interest is the close interconnection between gut microbiota dysbiosis and obesity and diabetes progression. Hence, microbiota manipulation through diet has been postulated as a promising therapeutic target. In this regard, secretion of gut microbiota-derived extracellular vesicles is gaining special attention, standing out as key factors that could mediate gut microbiota-host communication. Extracellular vesicles (EVs) derived from gut microbiota and probiotic bacteria allow to encapsulate a wide range of bioactive molecules (such as/or including proteins and nucleic acids) that could travel short and long distances to modulate important biological functions with the overall impact on the host health. EV-derived from specific bacteria induce differential physiological responses. For example, a high-fat diet-induced increase of the proteobacterium Pseudomonas panacis-derived EV is closely associated with the progression of metabolic dysfunction in mice. In contrast, Akkermansia muciniphila EV are linked with the alleviation of high-fat diet-induced obesity and diabetes in mice. Here, we review the newest pieces of evidence concerning the potential role of gut microbiota and probiotic-derived EV on obesity and diabetes onset, progression, and management, through the modulation of inflammation, metabolism, and gut permeability. In addition, we discuss the role of certain dietary patterns on gut microbiota-derived EV profile and the clinical implication that dietary habits could have on metabolic diseases progression through the shaping of gut microbiota-derived EV.

Adiponectin overexpression in C2C12 myocytes increases lipid oxidation and myofiber transition.

Metabolic syndrome and obesity have detrimental effects on the metabolic function of the skeletal muscle. Mounting evidence indicates that patients with those conditions may present an increased ratio of glycolytic to oxidative fibers associated with a decrease in oxidative capacity. In this regard, adiponectin, a hormone mainly secreted by adipocytes that regulates glucose and lipid metabolism, has emerged as a myokine that could play an important role in this process. We aimed to investigate whether adiponectin overexpression in skeletal muscle might be a local protective mechanism, favoring fatty acid utilization. To that end, we generated an in vitro model of myocytes with upregulated endogenous adiponectin using a lentiviral carrier. We demonstrated that the adiponectin-transduced myocytes were able to produce and secrete fully functional adiponectin complexes. Adiponectin overexpression remarkably upregulated the mRNA level of myogenic regulatory factors as well as genes implicated in lipolysis (HSL, ATGL) and cellular and mitochondrial fatty acid transport (LPL, CD36, CPT1B). This was accompanied by increased isoproterenol-induced lipolysis and ß-oxidation and reduced lipogenesis, whereas insulin-stimulated glucose uptake was unaltered in transduced myocytes. Lastly, the relative expression of the more glycolytic myofibers (MyHC IIb) compared to the more oxidative ones (MyHC I) was notably reduced. Our results showed that the released adiponectin acted in an autocrine/paracrine manner, increasing lipid oxidation in myocytes and leading to a transition of myofibers from the glycolytic to the oxidative type. In conclusion, muscle adiponectin overexpression might be a way to relieve muscle diseases caused by oxidative muscle fiber deficiency.

Uraemic sera stimulate lipolysis in human adipocytes: role of perilipin.

BACKGROUND: Although chronic kidney disease (CKD) is associated with dyslipidaemia and insulin resistance, the exact cause(s) are unknown. Since adipose tissue plays an important role in the development of these complications, we investigated the effect of uraemic sera on human adipocytes in vitro. METHODS: Cultured human adipocytes were incubated for 48 h with media containing sera from eight CKD Stage 5 patients or four (matched for age, sex and body mass index) healthy controls. Glycerol release (an index of lipolysis) was determined in conditioned media. RNA was isolated from the cells and quantitative polymerase chain reaction of genes involved in lipolysis was performed. In vivo lipolysis was determined by the plasma glycerol/total fat mass (from dual energy X-ray absorptiometry) ratio in 28 CKD patients and 28 matched controls. RESULTS: Incubation with uraemic, but not control, sera resulted in a significant ∼30% increase in spontaneous (basal) lipolysis (P <0.05). Furthermore, uraemic but not control sera induced a selective ∼30% reduction of messenger RNA (mRNA) coding for the lipid-droplet-associated protein perilipin (PLIN) (P <0.05), while mRNA levels of lipases, adipokines and differentiation factors did not differ between the groups after incubation. Also, consistent with our in vitro data, in vivo plasma glycerol/fat mass ratio was significantly elevated in uraemic patients as compared to controls (5.23 ± 4.1 versus 3.41 ± 2.3 µM/kg, P < 0.05). CONCLUSIONS: Undefined circulating factors in CKD patients increase basal lipolysis in human adipocytes in vitro, probably by attenuating the expression of the lipolytic regulator PLIN. Since in vivo lipolysis is a well-established risk factor for insulin resistance and cardiovascular disease, these effects may promote increased morbidity and mortality in CKD.

Changes in miRNA expression with two weight-loss dietary strategies in a population with metabolic syndrome.

OBJECTIVES: This study aimed to analyze the expression pattern of microRNAs (miRNAs) in white blood cells (WBC) in response to two different energy-restricted diets in patients with metabolic syndrome in the Metabolic Syndrome Reduction in Navarra-Spain (RESMENA) study. METHODS: A subsample of 24 patients with metabolic syndrome features from the randomized, prospective, parallel-designed RESMENA study was selected for this analysis. The RESMENA study consisted of two dietary strategies with a 30% energy restriction: RESMENA (high meal frequency and high adherence to the Mediterranean diet) and control (based on recommendations from the American Heart Association) groups. Anthropometric and biochemical parameters as well as miRNA expression in WBC by miRNA-seq were measured before and after 8 wk of intervention. RESULTS: A total of 49 miRNAs were differentially expressed after 8 wk of dietary intervention, 35 from the American Heart Association and 14 from the RESMENA diet. MiR-410, miR-637, miR-214, and miR-190 evidenced the most significant expression changes due to the weight loss intervention (P < 0.01). MiR-2115, -587, and -96 showed differential expressions between the two dietary strategies after 8 wk of intervention. The expression of several miRNAs was significantly associated with anthropometric and biochemical parameters: miR-410 levels positively correlated with circulating leptin and body mass index (BMI), and miR-587 expression was associated with vascular cell adhesion protein 1. CONCLUSIONS: Different dietary patterns induce specific changes in miRNA expression in WBC. The associations of specific miRNAs with biochemical and anthropometric parameters suggest that these miRNAs might be directly or indirectly involved in the effects of weight-loss diets with different foods and macronutrient composition, and participate in the regulation of metabolic diseases.

Potential Mechanisms Linking Food-Derived MicroRNAs, Gut Microbiota and Intestinal Barrier Functions in the Context of Nutrition and Human Health.

MicroRNAs (miRNAs) are non-coding single-stranded RNA molecules from 18 to 24 nucleotides that are produced by prokaryote and eukaryote organisms, which play a crucial role in regulating gene expression through binding to their mRNA targets. MiRNAs have acquired special attention for their potential in cross kingdom communication, notably food-derived microRNAs (xenomiRs), which could have an impact on microorganism and mammal physiology. In this review, we mainly aim to deal with new perspectives on: (1) The mechanism by which food-derived xenomiRs (mainly dietary plant xenomiRs) could be incorporated into humans through diet, in a free form, associated with proteins or encapsulated in exosome-like nanoparticles. (2) The impact of dietary plant-derived miRNAs in modulating gut microbiota composition, which in turn, could regulate intestinal barrier permeability and therefore, affect dietary metabolite, postbiotics or food-derived miRNAs uptake efficiency. Individual gut microbiota signature/composition could be also involved in xenomiR uptake efficiency through several mechanisms such us increasing the bioavailability of exosome-like nanoparticles miRNAs. (3) Gut microbiota dysbiosis has been proposed to contribute to disease development by affecting gut epithelial barrier permeability. For his reason, the availability and uptake of dietary plant xenomiRs might depend, among other factors, on this microbiota-related permeability of the intestine. We hypothesize and critically review that xenomiRs-microbiota interaction, which has been scarcely explored yet, could contribute to explain, at least in part, the current disparity of evidences found dealing with dietary miRNA uptake and function in humans. Furthermore, dietary plant xenomiRs could be involved in the establishment of the multiple gut microenvironments, in which microorganism would adapt in order to optimize the resources and thrive in them. Additionally, a particular xenomiR could preferentially accumulate in a specific region of the gastrointestinal tract and participate in the selection and functions of specific gut microbial communities.

Effects of DHA-Rich n-3 Fatty Acid Supplementation and/or Resistance Training on Body Composition and Cardiometabolic Biomarkers in Overweight and Obese Post-Menopausal Women.

Resistance training (RT) and n-3 polyunsaturated fatty acids (n-3 PUFA) supplementation have emerged as strategies to improve muscle function in older adults. Overweight/obese postmenopausal women (55-70 years) were randomly allocated to one of four experimental groups, receiving placebo (olive oil) or docosahexaenoic acid (DHA)-rich n-3 PUFA supplementation alone or in combination with a supervised RT-program for 16 weeks. At baseline and at end of the trial, body composition, anthropometrical measures, blood pressure and serum glucose and lipid biomarkers were analyzed. Oral glucose tolerance tests (OGTT) and strength tests were also performed. All groups exhibit a similar moderate reduction in body weight and fat mass, but the RT-groups maintained bone mineral content, increased upper limbs lean mass, decreased lower limbs fat mass, and increased muscle strength and quality compared to untrained-groups. The RT-program also improved glucose tolerance (lowering the OGTT incremental area under the curve). The DHA-rich supplementation lowered diastolic blood pressure and circulating triglycerides and increased muscle quality in lower limbs. In conclusion, 16-week RT-program improved segmented body composition, bone mineral content, and glucose tolerance, while the DHA-rich supplement had beneficial effects on cardiovascular health markers in overweight/obese postmenopausal women. No synergistic effects were observed for DHA supplementation and RT-program combination.