Direct metabolic regulation in skeletal muscle and fat tissue by leptin: implications for glucose and fatty acids homeostasis

Medicinal Perspective of 2,4-Thiazolidinediones Derivatives: An Insight into Recent Advancements

2,4-Thiazolidinedione derivatives represent nitrogen-containing heterocyclic compounds utilized in type 2 diabetes mellitus management. Recent advances in medicinal chemistry have unveiled diverse therapeutic potentials and structural modifications of these derivatives. This review delves into novel TZD derivatives, encompassing their synthesis, structure-activity relationships, and pharmacokinetic profiles. Various therapeutic potentials of TZDs are explored, including anticancer, antimicrobial, anti-inflammatory, antioxidant, anticonvulsant, antihyperlipidemic, anticorrosive, and antitubercular activities. Additionally, it addresses mitigating side effects associated with marketed TZD derivatives such as weight gain, oedema, fractures, and congestive heart failure in type 2 diabetes mellitus management. The review elaborates on in vivo, in vitro, and ex vivo studies supporting different biological activities, alongside predicting ADME and drug-likeness properties of TZDs. Computational studies are also integrated to elucidate binding modes and affinities of novel TZD derivatives. Furthermore, a plethora of novel TZD derivatives with varied and enhanced therapeutic potentials are presented, warranting further evaluation of their biological activities.

Unravelling the mechanisms of underweight in Parkinson's disease by investigating into the role of gut microbiome

Approximately half of patients with Parkinson's disease (PD) suffer from unintentional weight loss and are underweight, complicating the clinical course of PD patients. Gut microbiota alteration has been proven to be associated with PD, and recent studies have shown that gut microbiota could lead to muscle wasting, implying a possible role of gut microbiota in underweight PD. In this study, we aimed to (1) investigate the mechanism underlying underweight in PD patients with respect to gut microbiota and (2) estimate the extent to which gut microbiota may mediate PD-related underweight through mediation analysis. The data were adapted from Hill-Burns et al., in which 330 participants (199 PD, 131 controls) were enrolled in the study. Fecal samples were collected from participants for microbiome analysis. 16S rRNA gene sequence data were processed using DADA2. Mediation analysis was performed to quantify the effect of intestinal microbial alteration on the causal effect of PD on underweight and to identify the key bacteria that significantly mediated PD-related underweight. The results showed that the PD group had significantly more underweight patients (body mass index (BMI) < 18.5) after controlling for age and sex. Ten genera and four species were significantly different in relative abundance between the underweight and non-underweight individuals in the PD group. Mediation analysis showed that 42.29% and 37.91% of the effect of PD on underweight was mediated through intestinal microbial alterations at the genus and species levels, respectively. Five genera (Agathobacter, Eisenbergiella, Fusicatenibacter, Roseburia, Ruminococcaceae_UCG_013) showed significant mediation effects. In conclusion, we found that up to 42.29% of underweight PD cases are mediated by gut microbiota, with increased pro-inflammatory bacteria and decreased SCFA-producing bacteria, which indicates that the pro-inflammatory state, disturbance of metabolism, and interference of appetite regulation may be involved in the mechanism of underweight PD.

Transcriptional and epigenetic changes after dietary and surgical weight loss interventions in an animal model of obesity

BACKGROUND

Identifying determinants that can predict response to weight loss interventions is imperative for optimizing therapeutic benefit. We aimed to identify changes in DNA methylation and mRNA expression of a subset of target genes following dietary and surgical interventions in high-fat-diet (HFD)-induced obese rats.

METHODS

Forty-two adult Wistar Han male rats were divided into two groups: control rats (n = 7) and obese rats (n = 28), fed a HFD for 10 weeks (t10). Obese rats were randomly subdivided into five intervention groups (seven animals per group): (i) HFD; (ii) very-low-calorie diet (VLCD); (iii) sham surgery, and (iv) sleeve gastrectomy (SG). At week sixteen (t16), animals were sacrificed and tissue samples were collected to analyze changes in DNA methylation and mRNA expression of the selected genes.

RESULTS

By type of intervention, the surgical procedures led to the greatest weight loss. Changes in methylation and/or expression of candidate genes occurred proportionally to the effectiveness of the weight loss interventions. Leptin expression, increased sixfold in the visceral fat of the obese rats, was partially normalized after all interventions. The expression of fatty acid synthase (FASN) and monocyte chemoattractant protein 1 (MCP-1) genes, which was reduced 0.5- and 0.15-fold, respectively, in the liver tissue of obese rats, were completely normalized after weight loss interventions, particularly after surgical interventions. The upregulation of FASN and MCP-1 gene expression was accompanied by a significant reduction in promoter methylation, up to 0.5-fold decrease in the case of the FASN (all intervention groups) and a 0.8-fold decrease in the case of the MCP-1 (SG group).

CONCLUSIONS

Changes in tissue expression of specific genes involved in the pathophysiological mechanisms of obesity can be significantly attenuated following weight loss interventions, particularly surgery. Some of these genes are regulated by epigenetic mechanisms.

Melatonin Alleviates the Impairment of Muscle Bioenergetics and Protein Quality Control Systems in Leptin-Deficiency-Induced Obesity

Leptin is critically compromised in the major common forms of obesity. Skeletal muscle is the main effector tissue for energy modification that occurs as a result of the effect of endocrine axes, such as leptin signaling. Our study was carried out using skeletal muscle from a leptin-deficient animal model, in order to ascertain the importance of this hormone and to identify the major skeletal muscle mechanisms affected. We also examined the therapeutic role of melatonin against leptin-induced muscle wasting. Here, we report that leptin deficiency stimulates fatty acid β-oxidation, which results in mitochondrial uncoupling and the suppression of mitochondrial oxidative damage; however, it increases cytosolic oxidative damage. Thus, different nutrient-sensing pathways are disrupted, impairing proteostasis and promoting lipid anabolism, which induces myofiber degeneration and drives oxidative type I fiber conversion. Melatonin treatment plays a significant role in reducing cellular oxidative damage and regulating energy homeostasis and fuel utilization. Melatonin is able to improve both glucose and mitochondrial metabolism and partially restore proteostasis. Taken together, our study demonstrates melatonin to be a decisive mitochondrial function-fate regulator in skeletal muscle, with implications for resembling physiological energy requirements and targeting glycolytic type II fiber recovery.

Phase Angle, Inflammation, and Sarcopenia in Late Postoperative Roux-En-Y Gastric Bypass

Sarcopenic obesity is characterized by a disproportion between the amount of muscle to fat. Contrary to most studies evaluating parameters related to sarcopenic obesity in the elderly, this study aims to evaluate the phase angle (PhA) and sarcopenia in young individuals pre- and post-Roux-en-Y gastric bypass. A total of 69 volunteers (46 women and 23 men; 38.5 ± 8.1 years) participated in this study. Body composition and PhA were assessed using BIA. Sarcopenia was assessed using a handgrip strength test (HGS) and gait speed (GS), and appendicular lean mass (ALM) was assessed using Dual Energy X-ray Absorptiometry (DXA). The PhA was significantly lower (p < 0.0007) and the resistance (R) significantly higher (p = 0.0026) in the postoperative group. HGS was negatively correlated with R (r = -0.63669; p < 0.0001), hs-CRP (r = -0.45436; p = 0.0197), and leptin (r = -0.46505; p = 0.0043). GS was negatively correlated with R (r = -0.36220; p = 0.0254), and ALM was negatively correlated with reactance (r = -0.49485; p = 0.0034) and R (r = -0.65797; p ≤ 0.0001). PhA and other components of BIA provide a good correlation with sarcopenia, especially regarding the reduction in muscle function, in an early form, in individuals in the pre- and postoperative period of gastric bypass.

A Skeletal Muscle-Centric View on Time-Restricted Feeding and Obesity under Various Metabolic Challenges in Humans and Animals

Nearly 50% of adults will suffer from obesity in the U.S. by 2030. High obesity rates can lead to high economic and healthcare burdens in addition to elevated mortality rates and reduced health span in patients. Emerging data demonstrate that obesity is a multifactorial complex disease with various etiologies including aging, a lifestyle of chronic high-fat diets (HFD), genetic predispositions, and circadian disruption. Time-restricted feeding/eating (TRF; TRE in humans) is an intervention demonstrated by studies to show promise as an effective alternative therapy for ameliorating the effects of obesity and metabolic disease. New studies have recently suggested that TRF/TRE modulates the skeletal muscle which plays a crucial role in metabolism historically observed to be impaired under obesity. Here we discuss recent findings regarding potential mechanisms underlying TRF's modulation of skeletal muscle function, metabolism, and structure which may shed light on future research related to TRF as a solution to obesity.

Flavonoid Intake From Cocoa-Based Products and Adiposity Parameters in Adolescents in Spain

Background

Cocoa-based products are a good source of flavonoids, which may have beneficial effects on metabolic health.

Objective

The aim of this study is to assess the relationship between flavonoids from cocoa-based products and adiposity parameters in adolescents.

Methods

A cross-sectional study was conducted involving 944 adolescents aged 11-14 years enrolled in the SI! Program for Secondary Schools trial in Spain with available baseline data from food frequency questionnaires and anthropometric measurements [weight, height, waist circumference (WC), and fat mass percentage (% FM) by bioimpedance analysis]. Fat mass index (FMI) and waist-to-height ratio (WHtR) were obtained by dividing fat mass by height and WC by height, respectively. Body mass index (BMI), WC, and FMI for age and gender z-score were calculated. Overweight/obesity was defined as BMI ≥ 85th percentile and excess adiposity as %FM or FMI ≥ 75th percentile. WC ≥ 90th percentile and WHtR with a 0.5 threshold were considered as criteria of abdominal obesity. Multilevel mixed-effect regressions were used to evaluate the association between flavonoids from cocoa-based products and adiposity parameters. Municipalities and schools were considered random effects.

Results

Participants with a higher flavonoid intake from cocoa-based products had lower WC z-score [B = -0.04, 95% CI (-0.07; -0.01), P-for trend = 0.045] and WHtR [B = -0.01, 95% CI (-0.02; -0.01), P- for trend < 0.001]. They also had lower probability of having abdominal obesity [OR 0.66, 95% CI (0.52; 0.85), P- for trend = 0.001]. Inverse associations were observed between flavonoids from cocoa powder and BMI z-score [B = -0.08, 95% CI (-0.12; -0.05), P < 0.001], WC z-score [B = -0.06, 95% CI (-0.11; -0.02), P = 0.003], WHtR [B = -0.01, 95% CI (-0.01; -0.00), P < 0.001], %FM [B = -1.11, 95% CI (-1.48; -0.75), P < 0.001], and FMI z-score [B = -0.18, 95% CI (-0.20; -0.17), P < 0.001]. Regarding dark chocolate, an inverse association only with WC z-score [B = -0.06, 95% CI (-0.08; -0.05), P < 0.001] was found. However, no association was observed between flavonoids from milk chocolate intake and anthropometric parameters.

Conclusions

A higher intake of flavonoids from cocoa-based products was associated with lower adiposity parameters and a lower probability of presenting abdominal obesity.

Muscle satellite cells are impaired in type 2 diabetic mice by elevated extracellular adenosine

Muscle regeneration is known to be defective under diabetic conditions. However, the underlying mechanisms remain less clear. Adult quiescent muscle satellite cells (MuSCs) from leptin-receptor-deficient (i.e., db/db) diabetic mice are defective in early activation in vivo, but not in culture, suggesting the involvement of pathogenic niche factors. Elevated extracellular adenosine (eAdo) and AMP (eAMP) are detected under diabetic conditions. eAdo and eAMP potently inhibit cell cycle re-entry of quiescent MuSCs and injury-induced muscle regeneration. Mechanistically, eAdo and eAMP engage the equilibrative Ado transporters (ENTs)-Ado kinase (ADK)-AMPK signaling axis in MuSCs to inhibit the mTORC1-dependent cell growth checkpoint. eAdo and eAMP also inhibit early activation of quiescent fibroadipogenic progenitors and human MuSCs by the same mechanism. Treatment of db/db diabetic mice with an ADK inhibitor partially rescues the activation defects of MuSCs in vivo. Thus, both ADK and ENTs represent potential therapeutic targets for restoring the regenerative functions of tissue stem cells in patients with diabetes.

Sex differences in regional adipose tissue depots pose different threats for the development of Type 2 diabetes in males and females

Type 2 diabetes mellitus (T2DM) affects males and females disproportionately. In midlife, more males have T2DM than females. The sex difference in T2DM prevalence is, in part, explained by differences in regional adipose tissue characteristics. With obesity, changes to regional adipokine and cytokine release increases the risk of T2DM in both males and females with males having greater levels of TNFα and females having greater levels of leptin, CRP, and adiponectin. Regional immune cell infiltration appears to be pathogenic in both sexes via different routes as males with obesity have greater VAT ATM and a decrease in the protective Treg cells, whereas females have greater SAT ATM and T cells. Lastly, the ability of female adipose tissue to expand all regions through hyperplasia, rather than hypertrophy, protects them against the development of large insulin-resistant adipocytes that dominate male adipose tissue. The objective of this review is to discuss how sex may affect regional differences in adipose tissue characteristics and how these differences may distinguish the development of T2DM in males and females. In doing so, we will show that the origins of T2DM development differ between males and females.

Sarcopenia is highly prevalent in children with autoimmune liver diseases and is linked to visceral fat and parent-perceived general health

BACKGROUND

Patients with autoimmune hepatitis (AIH) and primary or autoimmune sclerosing cholangitis are at nutritional risk; their body composition and has not been extensively studied. We aimed to describe their body composition and identify clinical links.

METHODS

Using magnetic resonance imaging (MRI), two reviewers segmented total psoas muscle area (tPMSA), visceral fat area (VFA) and subcutaneous fat area (mm² ) and measured visceral and subcutaneous thickness (mm). Clinical, laboratory and quality of life (QoL; using PedsQL) data were collected. Sarcopenia was defined as tPMSA ≤5th percentile. Analysis of variance, Wilcoxon rank test and multivariable modelling were performed. A paediatric cohort with non-alcoholic fatty liver disease (NAFLD) was used as a comparator following propensity score matching.

RESULTS

Fifty-eight patients with autoimmune liver disease (AILD) (33 [57%] with AIH) were included: median age 16 years (interquartile range [IQR]: 13-18), 33 (57%) male. Median time from diagnosis to MRI was 15 months (IQR: 2-39 months). Two patients (3%) had a BMIz indicative of mild malnutrition. tPMSA was measurable in 52 subjects (90%). Of those, 25 (48%) had sarcopenia. Sarcopenic patients had a lower blood urea nitrogen compared to non-sarcopenic (median [IQR]: 9.5 [8.0, 12.0] vs 11 [10, 14] mg/dL; P = .023). There was no difference in corticosteroid use between groups. The VFA of sarcopenic patients was higher (3156 [2064, 7492]) vs 2084 [688, 3092]) mm² ; P = .005). Patient-reported QoL negatively associated with VFA and general health negatively associated with VFA. Compared with NAFLD, the odds ratio for sarcopenia with AILD was 14.5 (95% confidence interval: 2.3-90.7).

CONCLUSION

In autoimmune liver diseases, sarcopenia is highly prevalent, associated with increased visceral fat and QoL.

The Impact of Long-term Physical Inactivity on Adipose Tissue Immunometabolism

CONTEXT

Adipose tissue and physical inactivity both influence metabolic health and systemic inflammation, but how adipose tissue responds to chronic physical inactivity is unknown.

OBJECTIVE

This work aimed to characterize the impact of chronic physical inactivity on adipose tissue in healthy, young males.

METHODS

We collected subcutaneous adipose tissue from 20 healthy, young men before and after 60 days of complete bed rest with energy intake reduced to maintain energy balance and fat mass. We used RNA sequencing, flow cytometry, ex vivo tissue culture, and targeted protein analyses to examine adipose tissue phenotype.

RESULTS

Our results indicate that the adipose tissue transcriptome, stromal cellular compartment, and insulin signaling protein abundance are largely unaffected by bed rest when fat mass is kept stable. However, there was an increase in the circulating concentration of several adipokines, including plasma leptin, which was associated with inactivity-induced increases in plasma insulin and absent from adipose tissue cultured ex vivo under standardized culture conditions.

CONCLUSION

Physical inactivity-induced disturbances to adipokine concentrations such as leptin, without changes to fat mass, could have profound metabolic implications outside a clinical facility when energy intake is not tightly controlled.

Associations of plasma metal levels with type 2 diabetes and the mediating effects of microRNAs

The present study aims to determine the associations of multiple plasma metal levels and plasma microRNAs (miRNAs) with diabetes risk, and further explore the mediating effects of plasma miRNAs on the associations of plasma metal with diabetes risk. We detected plasma levels of 23 metals by inductively coupled plasma mass spectrometry (ICP-MS) among 94 newly diagnosed and untreated diabetic cases and 94 healthy controls. The plasma miRNAs were examined by microRNA Array screening and Taqman real-time PCR validation among the same study population. The multivariate logistic regression models were employed to explore the associations of plasma metal and miRNAs levels with diabetes risk. Generalized linear regression models were utilized to investigate the relationships between plasma metal and plasma miRNAs, and mediation analysis was used to assess the mediating effects of plasma miRNAs on the relationships between plasma metals and diabetes risk. Plasma aluminum (Al), titanium (Ti), copper (Cu), zinc (Zn), selenium (Se), rubidium (Rb), strontium (Sr), barium (Ba), and Thallium (Tl) levels were correlated with elevated diabetic risk while molybdenum (Mo) with decreased diabetic risk (P < 0.05 after FDR multiple correction). MiR-122-5p and miR-3141 were positively associated with diabetes risk (all P < 0.05). Ti, Cu, and Zn were positively correlated with miR-122-5p (P = 0.001, 0.028 and 0.004 respectively). Ti, Cu, and Se were positively correlated with miR-3141 (P = 0.003, 0.015, and 0.031 respectively). In addition, Zn was positively correlated with miR-193b-3p (P = 0.002). Ti was negatively correlated with miR-26b-3p (P = 0.016), while Mo and miR-26b-3p were positively correlated (P = 0.042). In the mediation analysis, miR-122-5p mediated 48.0% of the association between Ti and diabetes risk. The biological mechanisms of the association are needed to be explored in further studies.

Progenitor with cardiometabolic disorders increases food intake, systemic inflammation and gut microbiota alterations in the second generation offspring

This work presents the effects of the high-fat diet (H) consumed by the progenitor (G0) on cardiometabolic disorders and on intestinal microbiota in the second generation ofspring (F2). Rats submitted...

Profiling of ob/ob mice skeletal muscle exosome-like vesicles demonstrates combined action of miRNAs, proteins and lipids to modulate lipid homeostasis in recipient cells

We have determined the lipid, protein and miRNA composition of skeletal muscle (SkM)-released extracellular vesicles (ELVs) from Ob/ob (OB) vs wild-type (WT) mice. The results showed that atrophic insulin-resistant OB-SkM released less ELVs than WT-SkM, highlighted by a RAB35 decrease and an increase in intramuscular cholesterol content. Proteomic analyses of OB-ELVs revealed a group of 37 proteins functionally connected, involved in lipid oxidation and with catalytic activities. OB-ELVs had modified contents for phosphatidylcholine (PC 34-4, PC 40-3 and PC 34-0), sphingomyelin (Sm d18:1/18:1) and ceramides (Cer d18:1/18:0) and were enriched in cholesterol, likely to alleviated intracellular accumulation. Surprisingly many ELV miRNAs had a nuclear addressing sequence, and targeted genes encoding proteins with nuclear activities. Interestingly, SkM-ELV miRNA did not target mitochondria. The most significant function targeted by the 7 miRNAs altered in OB-ELVs was lipid metabolism. In agreement, OB-ELVs induced lipid storage in recipient adipocytes and increased lipid up-take and fatty acid oxidation in recipient muscle cells. In addition, OB-ELVs altered insulin-sensitivity and induced atrophy in muscle cells, reproducing the phenotype of the releasing OB muscles. These data suggest for the first time, a cross-talk between muscle cells and adipocytes, through the SkM-ELV route, in favor of adipose tissue expansion.

Effect of presurgical aerobic exercise on cardiometabolic health 30 days after bariatric surgery

We evaluated the effect of preoperative standard medical care (SC) vs. unsupervised aerobic exercise combined with SC (EX + SC) on cardiometabolic health and quality of life (QoL) 30 days after bariatric surgery. Bariatric patients (n = 14, age: 42.3 ± 2.5 years, body mass index: 45.1 ± 2.5 kg/m2 ) were match-paired to presurgical SC (n = 7) or EX + SC (n = 7; walking 30 min/day, 5 day/week, 65-85% HRpeak ) for 30 days. Body composition, peak cardiorespiratory fitness (VO2 peak), QoL, inflammation (adiponectin, leptin, cytokeratin-18), and a 120 min mixed meal tolerance test was performed to assess aortic waveforms (augmentation index, AIx@75), insulin sensitivity, and glucose total area under the curve (tAUC) at the time of surgery (post-intervention) and 30 days post-surgery. EX + SC had significantly higher high molecular weight (HMW) adiponectin (p = 0.01) and ratio of HMW to total adiponectin (p = 0.04) than SC at 30 days post-surgery, although they significantly (p = 0.006; ES = 1.86) decreased total time spent in moderate to vigorous physical activity (MVPA). SC had a significantly greater increase in VO2 peak (p = 0.02; ES = 1.54) and decrease in 120 min AIx@75 (p = 0.02; ES = 1.78) than EX + SC during the post-surgical period. The increase in MVPA was associated with a reduction in cytokeratin-18 (r = -0.67, p = 0.02). Increased VO2 peak was associated with increased activity/mobility QoL domain (r = 0.52, p = 0.05) and decreased 120 min AIx@75 (r = -0.61, p = 0.03) from surgery to post-surgery. Preoperative EX + SC did not maintain more favorable cardiometabolic health 30 days post-operation in this pilot study. However, changes in MVPA appear important for QoL and should be considered in future work.

Proteomic profiling of low muscle and high fat mass: a machine learning approach in the KORA S4/FF4 study

BACKGROUND

The coexistence of low muscle mass and high fat mass, two interrelated conditions strongly associated with declining health status, has been characterized by only a few protein biomarkers. High-throughput proteomics enable concurrent measurement of numerous proteins, facilitating the discovery of potentially new biomarkers.

METHODS

Data derived from the prospective population-based Cooperative Health Research in the Region of Augsburg S4/FF4 cohort study (median follow-up time: 13.5 years) included 1478 participants (756 men and 722 women) aged 55-74 years in the cross-sectional and 608 participants (315 men and 293 women) in the longitudinal analysis. Appendicular skeletal muscle mass (ASMM) and body fat mass index (BFMI) were determined through bioelectrical impedance analysis at baseline and follow-up. At baseline, 233 plasma proteins were measured using proximity extension assay. We implemented boosting with stability selection to enable false positives-controlled variable selection to identify new protein biomarkers of low muscle mass, high fat mass, and their combination. We evaluated prediction models developed based on group least absolute shrinkage and selection operator (lasso) with 100× bootstrapping by cross-validated area under the curve (AUC) to investigate if proteins increase the prediction accuracy on top of classical risk factors.

RESULTS

In the cross-sectional analysis, we identified kallikrein-6, C-C motif chemokine 28 (CCL28), and tissue factor pathway inhibitor as previously unknown biomarkers for muscle mass [association with low ASMM: odds ratio (OR) per 1-SD increase in log2 normalized protein expression values (95% confidence interval (CI)): 1.63 (1.37-1.95), 1.31 (1.14-1.51), 1.24 (1.06-1.45), respectively] and serine protease 27 for fat mass [association with high BFMI: OR (95% CI): 0.73 (0.61-0.86)]. CCL28 and metalloproteinase inhibitor 4 (TIMP4) constituted new biomarkers for the combination of low muscle and high fat mass [association with low ASMM combined with high BFMI: OR (95% CI): 1.32 (1.08-1.61), 1.28 (1.03-1.59), respectively]. Including protein biomarkers selected in ≥90% of group lasso bootstrap iterations on top of classical risk factors improved the performance of models predicting low ASMM, high BFMI, and their combination [delta AUC (95% CI): 0.16 (0.13-0.20), 0.22 (0.18-0.25), 0.12 (0.08-0.17), respectively]. In the longitudinal analysis, N-terminal prohormone brain natriuretic peptide (NT-proBNP) was the only protein selected for loss in ASMM and loss in ASMM combined with gain in BFMI over 14 years [OR (95% CI): 1.40 (1.10-1.77), 1.60 (1.15-2.24), respectively].

CONCLUSIONS

Proteomic profiling revealed CCL28 and TIMP4 as new biomarkers of low muscle mass combined with high fat mass and NT-proBNP as a key biomarker of loss in muscle mass combined with gain in fat mass. Proteomics enable us to accelerate biomarker discoveries in muscle research.

Dnmt3b Deficiency in Myf5+-Brown Fat Precursor Cells Promotes Obesity in Female Mice

Increasing energy expenditure through activation of brown fat thermogenesis is a promising therapeutic strategy for the treatment of obesity. Epigenetic regulation has emerged as a key player in regulating brown fat development and thermogenic program. Here, we aimed to study the role of DNA methyltransferase 3b (Dnmt3b), a DNA methyltransferase involved in de novo DNA methylation, in the regulation of brown fat function and energy homeostasis. We generated a genetic model with Dnmt3b deletion in brown fat-skeletal lineage precursor cells (3bKO mice) by crossing Dnmt3b-floxed (fl/fl) mice with Myf5-Cre mice. Female 3bKO mice are prone to diet-induced obesity, which is associated with decreased energy expenditure. Dnmt3b deficiency also impairs cold-induced thermogenic program in brown fat. Surprisingly, further RNA-seq analysis reveals a profound up-regulation of myogenic markers in brown fat of 3bKO mice, suggesting a myocyte-like remodeling in brown fat. Further motif enrichment and pyrosequencing analysis suggests myocyte enhancer factor 2C (Mef2c) as a mediator for the myogenic alteration in Dnmt3b-deficient brown fat, as indicated by decreased methylation at its promoter. Our data demonstrate that brown fat Dnmt3b is a key regulator of brown fat development, energy metabolism and obesity in female mice.

Examining the Association Between Serum Leptin and Sarcopenic Obesity

Objective

Sarcopenic obesity is an emerging geriatric syndrome among elderly individuals. Studies revealed a complicated pathogenesis between sarcopenia and obesity. Leptin, a proinflammatory adipokine, has been implicated in the mechanism of sarcopenic obesity. This study investigated the relationship between serum leptin level and sarcopenic obesity.

Methods

The study included 4063 participants aged 60 years and older from the NHANES III database. Sarcopenia was defined as a skeletal muscle index (SMI) less than one standard deviation below the young adult value. Obesity was defined as a body mass index (BMIF) over 30 kg/m². Multivariate regression analysis was performed to examine the association between serum leptin level and sarcopenic obesity.

Results

In adjusted models, serum leptin level was positively correlated with BMI (β: 1.33, p value < 0.001) and negatively correlated with SMI (β: −0.091, p value = 0.001). A significant association between serum leptin level and sarcopenic obesity was found in multivariate analysis (β: 4.011, p value=0.014).

Conclusion

Our study demonstrated that serum leptin level was related to an increased risk of sarcopenic obesity. This epidemiologic finding suggests that leptin may play a role in sarcopenic obesity.

Effects of high fat diets and supplemental tart cherry and fish oil on obesity and type 2 diabetes in male and female C57BL/6J and TALLYHO/Jng mice

Obesogenic and diabetogenic high fat (HF) diets can influence genetic factors in disease development with sexual dimorphic responses. We investigated potential protective effects of tart cherry (TC), fish oil (FO) and TC+FO supplementation in TALLYHO/Jng (TH) and C57BL/6J (B6) mice fed HF diets. Male and female TH and B6 mice were weaned onto five different diets; low fat (LF), HF, and HF supplemented with TC, FO, or TC+FO and maintained. For both males and females on LF, TH mice were heavier and fatter than B6, which was accentuated by HF in males, but not in females. TH males, but not others, developed severe glucose intolerance and hyperglycemia on HF, with reduced mRNA levels of Adipoq and Esr1 in adipose tissue. Considering energy balance, locomotor activity was lower in TH mice than B6 for both sexes without diet effects, except B6 females where HF decreased it. Compared to LF, HF decreased energy expenditure, RER, and food intake (in grams) for both sexes without strain differences. In all mice, but B6 males, HF increased plasma IL6 levels compared to LF. No preventive effects of TC, FO or TC+FO were noted for HF-induced obesity or energy imbalance, but FO alleviated glucose intolerance in TH males. Further, TC and FO decreased plasma IL6 levels, especially in females, without additive or synergistic effects of these two. Collectively, obesogenic and diabetogenic impacts of HF diets differed depending on the genetic predisposition. Moreover, sexually dimorphic effects of dietary supplementation were observed for glucose metabolism and inflammatory markers.

Health-Promoting Functions of the Marine Carotenoid Fucoxanthin

Fucoxanthin (Fx) is a marine carotenoid found in brown seaweeds and several marine microalgae. Recent studies have reported that dietary Fx exhibits many health-promoting functions such as anti-obesity and anti-diabetic effects in animal experiments. A human clinical trial of Fx showed high potential on reduction of body weight and fat content. The anti-obesity effect of Fx is due to several mechanisms, which include the suppression of adipocyte differentiation, anti-inflammation, and uncouple protein 1 induction in white adipose tissue. Furthermore, Fx reduced blood glucose level and improved insulin resistance through the regulation of adipokine mRNA expressions. In this chapter, we reviewed health beneficial effects and safety of Fx and discussed their molecular mechanisms.

Short-chain fatty acids as potential regulators of skeletal muscle metabolism and function

A key metabolic activity of the gut microbiota is the fermentation of non-digestible carbohydrate, which generates short-chain fatty acids (SCFAs) as the principal end products. SCFAs are absorbed from the gut lumen and modulate host metabolic responses at different organ sites. Evidence suggests that these organ sites include skeletal muscle, the largest organ in humans, which plays a pivotal role in whole-body energy metabolism. In this Review, we evaluate the evidence indicating that SCFAs mediate metabolic cross-talk between the gut microbiota and skeletal muscle. We discuss the effects of three primary SCFAs (acetate, propionate and butyrate) on lipid, carbohydrate and protein metabolism in skeletal muscle, and we consider the potential mechanisms involved. Furthermore, we highlight the emerging roles of these gut-derived metabolites in skeletal muscle function and exercise capacity, present limitations in current knowledge and provide suggestions for future work.

The Q223R Polymorphism of the Leptin Receptor Gene as a Predictor of Weight Gain in Childhood Obesity and the Identification of Possible Factors Involved

(1) Background: Childhood rapid weight gain during development has been postulated as a predictor of obesity. The objective of this study was to investigate the effect of single nucleotide polymorphisms (SNPs) on the annual weight gain and height growth, as well as identifying possible lifestyle factors involved. (2) Methods: As part of the GENYAL study, 221 children (6–8 years old) of Madrid (Spain) were enrolled. A total of 11 SNPs associated with high childhood body mass indexes (BMIs) were assessed. Anthropometric measurements, dietary and physical activity data, were collected in 2017 and 2018. Bonferroni-corrected linear models were used to fit the data. (3) Results: A significant association between the Q223R LEPR and the weight growth was found, showing a different behavior between GA and GG genotypes (p = 0.001). Regarding lifestyle factors, an interaction between Q223R genotypes and total active weekly hours/week to predict the weight growth (kg/year) was observed (p = 0.023). In all the genotypes, a beneficial effect against rapid weight growth was observed, but the effect size of the interaction was much more significant in homozygous (GG) minor homozygous (β = −0.61 (−0.95, −0.26) versus heterozygous (AG) and wild-type homozygous (AA) genotypes (β = −0.07 (−0.24, 0.09) and β = −0.12 (−0.32, 0.08), respectively). (4) Conclusions: These results may contribute to more personalized recommendations to prevent childhood obesity.

Fuzhu jiangtang granules combined with metformin reduces insulin resistance in skeletal muscle of diabetic rats via PI3K/Akt signaling

Context: Fuzhu Jiangtang Granules (FJG) are a traditional Chinese used in the treatment of diabetes mellitus. However, the antidiabetic mechanism of FJG is not clear. Objective: This study evaluates and determines the antidiabetic mechanism of FJG using a Zucker diabetic fatty (ZDF) rat model. Materials and methods: ZDF (fa/fa) rats were divided into four groups (n = 6): diabetes mellitus (DM), metformin (Met, 0.134 g/kg b.w./day), FJG (0.64 g/kg b.w./day), and combination (Com, 0.134 g/kg b.w./day of Met and 0.64 g/kg b.w./day of FJG). Six ZDF (fa/+) rats served as a normal control. After 6 weeks, biochemical parameters gene and protein expression were detected. Results: The FBG, bodyweight, triglyceride (TG), total cholesterol (TC), free fatty acid (FFA), insulin levels, and HOMA-IR were lower in the FJG than in the DM group (p < 0.05, p < 0.01). In an oral glucose tolerance test, the AUC in the FJG group was significantly lower (p < 0.01). The levels of superoxide dismutase and catalase were higher in the FJG than in the DM group (p < 0.01); the malondialdehyde content and TNF-α were significantly decreased in the FJG group (p < 0.01). FJG increased the mRNA expression of IR and GLUT4 significantly (p < 0.05, p < 0.01). The protein levels of IR, p-IRS1 tyr989, m-PI3Kp85, p-Akt and GLUT4 were increased in the FJG (p < 0.05, p < 0.01), but the protein levels of p-IRS1 ser1101/612/307 were significantly decreased in the JG group (p < 0.01). Discussion and conclusions: The antidiabetic mechanism of FJG may be related to regulation of the insulin-signaling pathway in skeletal muscle. These aspects require further research.

Leptin receptor mediates the proliferation and glucose metabolism of pancreatic cancer cells via AKT pathway activation

Pancreatic cancer (PC) is the fourth leading cause of cancer‑related mortality worldwide. Leptin is an adipokine that is significantly increased in obese patients and that functions in various biological processes of cancer, such as tumor growth and metastasis. However, its role in PC cell proliferation and glucose metabolism and the underlying mechanisms remain unclear. In the present study, in vitro leptin treatment significantly promoted cell proliferation and increased glucose uptake and lactate production of human PC and healthy pancreas cells in a dose‑dependent manner, accompanied by increased expression of the glycolytic enzymes hexokinase II and glucose transporter 1. Furthermore, leptin receptor‑specific short hairpin RNAs were used to silence leptin receptor expression in PC cells, which had the opposite effect to leptin stimulation and decreased AKT phosphorylation. In addition, the effects of leptin stimulation were significantly counteracted by the AKT inhibitor LY294002, whereas the effects of leptin silencing were counteracted by AKT activator insulin‑like growth factor 1. The results of the present study suggested that leptin may contribute to cell proliferation and glucose metabolism of human PC cells, which may be through activation of the AKT pathway.

Changes in Satiety Hormones in Response to Leptin Treatment in a Patient with Leptin Deficiency

BACKGROUND

We tested whether leptin treatment affects secretion of satiety-related gut peptides and brain-derived neurotrophic factor (BDNF), which is a regulator of energy homeostasis downstream of hypothalamic leptin signaling.

METHODS

We report the case of a morbidly obese 14.7-year-old girl with a novel previously reported homozygous leptin gene mutation, in whom hormone secretion was evaluated in 30-min intervals for 10 h (07.30-17.30) to assess BDNF, insulin, glucagon-like peptide-1 (GLP-1), ghrelin, and peptide YY (PYY) secretion before as well as 11 and 46 weeks after start of metreleptin treatment.

RESULTS

Leptin substitution resulted in strong reductions of body fat and calorie intake. Insulin secretion increased by 58.9% after 11 weeks, but was reduced by -44.8% after 46 weeks compared to baseline. Similarly, GLP-1 increased after 11 weeks (+15.2%) and decreased after 46 weeks. PYY increased consistently (+5%/ +13.2%, after 11/46 weeks). Ghrelin decreased after 46 weeks (-11%). BDNF secretion was not affected by leptin treatment.

CONCLUSION

The strong increase in insulin and GLP-1 secretion after 11 weeks of metreleptin treatment cannot be explained by reduced adiposity and might contribute to improved central satiety. Observed changes of PYY can lead to increased satiety as well. However, leptin replacement does not seem to affect circulating BDNF levels.

Fatty Liver and Autoimmune Hepatitis: Two Forms of Liver Involvement in Lipodystrophies

INTRODUCTION

Lipodystrophies are a heterogeneous group of rare diseases (genetic or acquired) characterized by a partial or generalized deficit of adipose tissue, resulting in less energy storage capacity. They are associated with severe endocrine-metabolic complications with significant morbidity and mortality. In the pathogenesis of the acquired forms, immunological disorders may be involved.

CASE 1

A 13-year-old female was diagnosed with acquired generalized lipodystrophy and observed for suspicion of portal hypertension. She presented with generalized absence of adipose tissue, cervical and axillary acanthosis nigricans, and massive hepatosplenomegaly. Laboratory tests revealed AST 116 IU/L, ALT 238 IU/L, GGT 114 IU/L, HOMA-IR 28.2, triglycerides 491 mg/L, and leptin < 0.05 ng/mL. Upper gastrointestinal endoscopy saw no signs of portal hypertension. Hepatic histology showed macrovesicular fatty infiltration (60% of hepatocytes) and advanced fibrosis/cirrhosis. Her clinical condition worsened progressively to diabetes requiring treatment with subcutaneous insulin and hepatopulmonary syndrome.

CASE 2

A 15-year-old female, diagnosed with acquired partial lipodystrophy, Parkinson syndrome, autoimmune thyroiditis, and autoimmune thrombocytopenia was observed for hypertransaminasemia since the age of 8 years. She had absence of subcutaneous adipose tissue in the upper and lower limbs and ataxia. Laboratory tests showed AST 461 IU/L, ALT 921 IU/L, GGT 145 IU/L, HOMA-IR 32.6, triglycerides 298 mg/dL, normal leptin levels, platelets 84,000/μL, IgG 1,894 mg/dL, positive anti-LKM and anti-LC-1. Hepatic histology was suggestive of autoimmune hepatitis, without steatosis. She progressed favorably under metformin and immunosuppressive treatment.

CONCLUSION

Early recognition and adequate characterization of liver disease in lipodystrophies is essential for a correct treatment approach. In acquired generalized lipodystrophy, the severe endocrine-metabolic disorder, which leads to steatohepatitis with cirrhotic progression, may benefit from recombinant leptin treatment.

A possible association between fructose consumption and pulmonary emphysema

Chronic Obstructive Pulmonary Disease (COPD) is a syndrome that comprises several distinct and overlapping phenotypes. In addition to persistent airflow limitation and respiratory symptoms, COPD is also characterized by chronic systemic inflammation. Epidemiological studies have shown that dietary fibers, fruits and vegetables intake protects against the COPD development, while fructose-loading is associated with increased risk of asthma and chronic bronchitis. Since dietary factors might affect susceptibility to COPD by modulating oxidative stress and inflammatory responses, we evaluated how fructose feeding might affect the smoking-induced emphysema in mice. We found that chronic fructose intake induced destruction and remodeling of lung parenchyma and impairment of respiratory mechanics, which are associated with distinctive cytokine profiles in bronchoalveolar lavage fluid, blood plasma and skeletal muscle. The combined effects of chronic fructose intake and cigarette smoking on destruction of lung parenchyma are more pronounced than the effects of either alone. Excessive intake of fructose might directly cause pulmonary emphysema in mice rather than just altering its natural history by facilitating the installation of a low-grade systemic inflammatory milieu.

The host response to poly(lactide-co-glycolide) scaffolds protects mice from diet induced obesity and glucose intolerance

Underlying metabolic disease is poor adipose tissue function characterized by impaired glucose tolerance and low expression of health promoting adipokines. Currently, no treatments specifically target the adipose tissue and we are investigating polymer scaffolds for localized drug delivery as a therapeutic platform. In this work we implanted porous poly(lactide-co-glycolide) scaffolds into the epididymal fat of mice. Surprisingly, "empty" scaffolds decreased blood glucose levels in healthy mice as well as epididymal fat pad size. By injecting a fluorescent glucose tracer into mice, we determined that glucose uptake increases by 60% in epididymal fat pads with scaffolds; in contrast, glucose uptake was not elevated in other major metabolic organs, suggesting the enhanced glucose uptake at the scaffold implant site was responsible for decreased blood glucose levels. Histology indicated increased cellularity and tissue remodeling around the scaffold and we found increased expression of glucose transporter 1 and insulin-like growth factor 1, which are proteins involved in wound healing that can also modulate blood glucose levels through their promotion of glucose uptake. Regarding clinical translation, "empty" scaffolds decreased obesity and improved glucose tolerance in mice fed a high fat diet. These findings demonstrate increased cellular activity in the adipose tissue, such as that associated with the host response to biomaterial implant, is beneficial in mice suffering from metabolic complications of over nutrition, possibly because it mitigates the positive energy balance that leads to the obese, diabetic state. More broadly, this work reaffirms that in addition to the local host response typically investigated, biomaterial implant has systemic physiological effects and suggests that there may be implications for therapy.

Activation of antioxidant defences of human mammary epithelial cells under leptin depend on neoplastic state

BACKGROUND

Obesity is associated with oxidative stress, a major factor in carcinogenesis, and with high leptin concentration. The aim of this study was to determine the effects of leptin on the antioxidant response in three human mammary epithelial cells each presenting a different neoplastic status: healthy human mammary epithelial cells (HMEC), oestrogen-receptor positive MCF-7 cells and triple-negative MDA-MB-231 cells.

METHODS

This in vitro kinetic study characterized the cell antioxidant response after 1, 6 and 24 h in the presence of leptin (10 or 100 ng/ml).The antioxidant response was defined in terms of cell glutathione content, gene expression and catalytic activity of antioxidant enzymes (i.e. glutathione peroxidase 1 (Gpx1), glutathione reductase (GR), glutathione S transferase (GST), heme-oxygenase 1 (HO-1) and cyclooxygenase-2 (COX-2)). Oxidative stress occurrence was assessed by lipid hydro peroxide (HPLIP) and isoprostane concentrations in culture media at 24 h.

RESULTS

At both concentrations used, leptin induced ROS production in all cell models, contributing to various antioxidant responses linked to neoplastic cell status. HMEC developed a highly inducible antioxidant response based on antioxidant enzyme activation and an increase in cell GSH content at 10 ng/ml of leptin. However, at 100 ng/ml of leptin, activation of antioxidant response was lower. Conversely, in tumour cells, MCF-7 and MDA-MB-231, leptin did not induce an efficient antioxidant response, at either concentration, resulting in an increase of lipid peroxidation products.

CONCLUSIONS

Leptin can modulate the oxidative status of mammary epithelial cells differently according to their neoplastic state. These novel results shed light on oxidative status changes in mammary cells in the presence of leptin.

Serum leptin and leptin resistance correlations with NAFLD in patients with type 2 diabetes

AIMS

Leptin/leptin resistance has been suggested to play a role in nonalcoholic fatty liver disease (NAFLD), and therefore we investigated the correlation of leptin/leptin-receptor system with markers of hepatic steatosis (HS) and fibrosis (HF) in patients with type 2 diabetes (T2D).

MATERIALS AND METHODS

In 159 T2D subjects with disease duration of 6.0 (0.0-27.0) years, HS was evaluated by semi-quantitative ultrasonographic scores and by clinical/biochemical variables: Fatty liver index and Hepatic steatosis index. HF was evaluated by NAFLD fibrosis score (NAFLD-FS). Serum leptin and leptin receptor (sObR) concentrations were measured and leptin resistance estimated by Free Leptin Index (FLpI). Both simple and multiple correlations between the HS and HF with the three parameters of interest were examined.

RESULTS

Leptin levels and FLpI correlated with diabetes duration (0.25 [95%CI: 0.09-0.39] and 0.24 [95%CI: 0.08-0.39]; P < 0.01 for both). 76.1% of T2D patients had HS and 29% had HF. The univariate analysis indicated positive correlations of HS indexes with serum leptin, FLpI, and negative correlations with serum sObR (P < 0.0001 for all). In the multiple regression analysis leptin, sObR, FLpI, waist-to-hip ratio, HbA1c, lipids, and HOMA-IR correlated independently with HS (P < 0.0001 for all). Although the univariate analyses indicated weak correlations of NAFLD-FS with leptin, sObR, and FLpI, in the multiple regression analyses, only age and waist independently predicted HF.

CONCLUSION

In patients with T2D, HS correlated positively with serum leptin and leptin resistance, and negatively with sObR, along with variables of adiposity and metabolic control, but neither of them made a significant contribution to HF.

The Effects of a 12-Week Combined Exercise Training Program on Arterial Stiffness, Vasoactive Substances, Inflammatory Markers, Metabolic Profile, and Body Composition in Obese Adolescent Girls

PURPOSE

Childhood and adolescent obesity is a major international public health crisis. It is crucial to prevent the negative effects of obesity at an early age by implementing appropriate lifestyle interventions, such as exercise training. We evaluated the effects of a combined resistance and aerobic exercise training (CET) regimen on arterial stiffness, vasoactive substances, inflammatory markers, metabolic profile, and body composition in obese adolescent girls.

METHODS

A total of 30 obese adolescent girls were randomly assigned to a CET (n = 15) or a control group (n = 15). The CET group trained for 3 days per week. Plasma nitric oxide, endothelin-1, C-reactive protein, arterial stiffness, glucose, insulin, the adiponectin/leptin ratio, and body fat were measured before and after 12 weeks.

RESULTS

There were significant increases (P < .05) in nitric oxide (4.0 μM) and adiponectin/leptin ratio (0.33); and decreases (P < .05) in arterial stiffness (-1.0 m/s), C-reactive protein (-0.5 mg/L), glucose (-1.2 mmol/L), insulin (-17.1 μU/mL), and body fat (-3.6%) following CET compared with control. There were no significant changes in endothelin-1 after CET or control.

CONCLUSIONS

The findings of this study indicate that CET improves arterial stiffness, nitric oxide, and inflammatory and metabolic markers in obese adolescent girls. CET may have important health implications for the prevention of atherosclerosis at an early age.

Pro-inflammatory cytokines: The link between obesity and osteoarthritis

Osteoarthritis (OA), characterized by joint malfunction and chronic disability, is the most common form of arthritis. Clinical and animal experiments reveal that age-related OA is associated with many factors such as age, sex, trauma, and obesity. One of the most influential and modifiable risk factors is obesity. Obesity not only increases mechanical stress on the tibiofemoral cartilage, but also leads to a higher prevalence of OA in non-weight-bearing areas. There is a link between obesity and inflammation. Adipose tissues play a crucial role in this context because they are the major source of cytokines, chemokines, and metabolically-active mediators named adipokines. The adipokines, including adiponectin and leptin, have been demonstrated to regulate inflammatory immune responses in cartilage. Obese people and animals show a higher level of serum tumor necrosis factor-alpha (TNF-α), interleukin-1 beta (IL)-1β and IL-6, all of which are produced by macrophages derived from adipose tissue. These pro-inflammatory cytokines regulate the proliferation and apoptosis of adipocytes, promote lipolysis, inhibit lipid synthesis and decrease blood lipids through autocrine and paracrine mechanisms. Elevated levels of TNF-α, IL-1 and IL-6 have been found in the synovial fluid, synovial membrane, subchondral bone and cartilage of OA patients, confirming their important roles in OA pathogenesis. TNF-α, IL-6 and IL-1 are the factors released by fat to negatively regulate cartilage directly. Moreover, TNF-α, IL-1 and IL-6 can induce the production of other cytokines, matrix metalloproteinases (MMPs) and prostaglandins and inhibit the synthesis of proteoglycans and type II collagen; thus, they play a pivotal role in cartilage matrix degradation and bone resorption in OA. Activated chondrocytes also produce MMP-1, MMP-3, MMP-13, and aggrecanase 1 and 2 (ADAMTS-4, ADAMTS-5). In addition, IL-1, TNF-α and IL-6 may cause OA indirectly by regulating release of adiponectin and leptin from adipocytes. In this review, we first summarize the relationship between obesity and inflammation. Then we summarize the roles of IL-1, TNF-α and IL-6 in OA. We further discuss how IL-1, TNF-α and IL-6 regulate the communication between fat and OA, and their pathological roles in obesity-related OA. Lastly, we discuss the possibility of using the pro-inflammatory signaling pathway as a therapeutic target to develop drugs for obesity-related OA.

Emergence of Leptin in Infection and Immunity: Scope and Challenges in Vaccines Formulation

Deficiency of leptin (ob/ob) and/or desensitization of leptin signaling (db/db) and elevated expression of suppressor of cytokine signaling-3 (SOCS3) reported in obesity are also reported in a variety of pathologies including hypertriglyceridemia, insulin resistance, and malnutrition as the risk factors in host defense system. Viral infections cause the elevated SOCS3 expression, which inhibits leptin signaling. It results in immunosuppression by T-regulatory cells (Tregs). The host immunity becomes incompetent to manage pathogens' attack and invasion, which results in the accelerated infections and diminished vaccine-specific antibody response. Leptin was successfully used as mucosal vaccine adjuvant against Rhodococcus equi. Leptin induced the antibody response to Helicobacter pylori vaccination in mice. An integral leptin signaling in mucosal gut epithelial cells offered resistance against Clostridium difficile and Entameoba histolytica infections. We present in this review, the intervention of leptin in lethal diseases caused by microbial infections and propose the possible scope and challenges of leptin as an adjuvant tool in the development of effective vaccines.

Adipogenesis in fish

White adipose tissue (AT) is the main lipid storage depot in vertebrates. Initially considered to be a simple lipid store, AT has recently been recognized as playing a role as an endocrine organ that is implicated in processes such as energy homeostasis and as a rich source of stem cells. Interest in adipogenesis has increased not only because of the prevalence of obesity, metabolic syndrome and type 2 diabetes in humans, but also in aquaculture because of the excessive fat deposition experienced in some cultured fish species, which may compromise both their welfare and their final product quality. Adipocyte development is well conserved among vertebrates, and this conservation has facilitated the rapid characterization of several adipogenesis models in fish. This Review presents the main findings of adipogenesis research based in primary cultures of the preadipocytes of farmed fish species. Zebrafish has emerged as an excellent model for studying the early stages of adipocyte fish development in vivo. Nevertheless, larger fish species are more suitable for the isolation of preadipocytes from visceral AT and for studies in which preadipocytes are differentiated in vitro to form mature adipocytes. Differentiated adipocytes contain lipid droplets and express adipocyte marker genes such as those encoding the peroxisome proliferator activated receptor γ (pparγ), CCAAT-enhancer-binding protein α (c/ebpα), lipoprotein lipase (lpl), fatty acid synthase (fas), fatty acid binding protein 11 (fabp11), fatty acid transporter protein1 (fatp1), adiponectin and leptin. Differentiated adipocytes also have elevated glycerol 3-phosphate (G3P) dehydrogenase (GPDH) activity. To better understand fish adipocyte development and regulation, different adipokines, fatty acids, growth factors and PPAR agonists have been studied, providing relevant insights into which factors affect these processes and counterbalance AT dysregulation.

Transcriptional changes in mesenteric and subcutaneous adipose tissue from Holstein cows in response to plane of dietary energy

Background

Dairy cows can readily overconsume dietary energy during most of the prepartum period, often leading to higher prepartal concentrations of insulin and glucose and excessive body fat deposition. The end result of these physiologic changes is greater adipose tissue lipolysis post-partum coupled with excessive hepatic lipid accumulation and compromised health. Although transcriptional regulation of the adipose response to energy availability is well established in non-ruminants, such regulation in cow adipose tissue depots remains poorly characterized.

Results

Effects of ad-libitum access to high [HIGH; 1.62 Mcal/kg of dry matter (DM)] or adequate (CON; 1.35 Mcal/kg of DM) dietary energy for 8 wk on mesenteric (MAT) and subcutaneous (SAT) adipose tissue transcript profiles were assessed in non-pregnant non-lactating Holstein dairy cows using a 13,000-sequence annotated bovine oligonucleotide microarray. Statistical analysis revealed 409 and 310 differentially expressed genes (DEG) due to tissue and diet. Bioinformatics analysis was conducted using the Dynamic Impact Approach (DIA) with the KEGG pathway database. Compared with SAT, MAT had more active biological processes related to adipose tissue accumulation (adiponectin secretion) and signs of pro-inflammatory processes due to adipose tissue expansion and macrophage infiltration (generation of ceramides). Feeding the HIGH diet led to changes in mRNA expression of genes associated with cell hypertrophy (regucalcin), activation of adipogenesis (phospholipid phosphatase 1), insulin signaling activation (neuraminidase 1) and angiogenesis (semaphorin 4G, plexin B1). Further, inflammation due to HIGH was underscored by mRNA expression changes associated with oxidative stress response (coenzyme Q3, methyltransferase), ceramide synthesis (N-acylsphingosine amidohydrolase 1), and insulin signaling (interferon regulatory factor 1, phosphoinositide-3-kinase regulatory subunit 1, retinoic acid receptor alpha). Activation of ribosome in cows fed HIGH indicated the existence of greater adipocyte growth rate (M-phase phosphoprotein 10, NMD3 ribosome export adaptor).

Conclusions

The data indicate that long-term ad-libitum access to a higher-energy diet led to transcriptional changes in adipose tissue that stimulated hypertrophy and the activity of pathways associated with a slight but chronic inflammatory response. Further studies would be helpful in determining the extent to which mRNA results also occur at the protein level.

Reallocating sitting time to standing or stepping through isotemporal analysis: associations with markers of chronic low-grade inflammation

Although high levels of sitting time are adversely related to health, it is unclear whether moving from sitting to standing provides a sufficient stimulus to elicit benefits upon markers of chronic low-grade inflammation in a population at high risk of type 2 diabetes (T2DM). Three hundred and seventy two participants (age = 66.8 ± 7.5years; body mass index (BMI) = 31.7 ± 5.5kg/m²; Male = 61%) were included. Sitting, standing and stepping was determined using the activPAL3^TM device. Linear regression modelling employing an isotemporal substitution approach was used to quantify the association of theoretically substituting 60 minutes of sitting per day for standing or stepping on interleukin-6 (IL-6), C-reactive protein (CRP) and leptin. Reallocating 60 minutes of sitting time per day for standing was associated with a -4% (95% CI -7%, -1%) reduction in IL-6 (p = 0.048). Reallocating 60 minutes of sitting time for light stepping was also associated with lower IL-6 levels (-28% (-46%, -4%; p = 0.025)). Substituting sitting for moderate-to-vigorous (MVPA) stepping was associated with lower CRP (-41% (-75%, -8%; p = 0.032)), leptin (-24% (-34%, -12%; p ≤ 0.001)) and IL-6 (-16% (-28%, 10%; p = 0.036). Theoretically replacing 60 minutes of sitting per day with an equal amount of either standing or stepping yields beneficial associations upon markers of chronic-low grade inflammation.

Molecular Mechanisms of Obesity-Induced Osteoporosis and Muscle Atrophy

Obesity and osteoporosis are two alarming health disorders prominent among middle and old age populations, and the numbers of those affected by these two disorders are increasing. It is estimated that more than 600 million adults are obese and over 200 million people have osteoporosis worldwide. Interestingly, both of these abnormalities share some common features including a genetic predisposition, and a common origin: bone marrow mesenchymal stromal cells. Obesity is characterized by the expression of leptin, adiponectin, interleukin 6 (IL-6), interleukin 10 (IL-10), monocyte chemotactic protein-1 (MCP-1), tumor necrosis factor-alpha (TNF-α), macrophage colony stimulating factor (M-CSF), growth hormone (GH), parathyroid hormone (PTH), angiotensin II (Ang II), 5-hydroxy-tryptamine (5-HT), Advance glycation end products (AGE), and myostatin, which exert their effects by modulating the signaling pathways within bone and muscle. Chemical messengers (e.g., TNF-α, IL-6, AGE, leptins) that are upregulated or downregulated as a result of obesity have been shown to act as negative regulators of osteoblasts, osteocytes and muscles, as well as positive regulators of osteoclasts. These additive effects of obesity ultimately increase the risk for osteoporosis and muscle atrophy. The aim of this review is to identify the potential cellular mechanisms through which obesity may facilitate osteoporosis, muscle atrophy and bone fractures.

Tumour biology of obesity-related cancers: understanding the molecular concept for better diagnosis and treatment

Obesity continues to be a major global problem. Various cancers are related to obesity and proper understanding of their aetiology, especially their molecular tumour biology is important for early diagnosis and better treatment. Genes play an important role in the development of obesity. Few genes such as leptin, leptin receptor encoded by the db (diabetes), pro-opiomelanocortin, AgRP and NPY and melanocortin-4 receptors and insulin-induced gene 2 were linked to obesity. MicroRNAs control gene expression via mRNA degradation and protein translation inhibition and influence cell differentiation, cell growth and cell death. Overexpression of miR-143 inhibits tumour growth by suppressing B cell lymphoma 2, extracellular signal-regulated kinase-5 activities and KRAS oncogene. Cancers of the breast, uterus, renal, thyroid and liver are also related to obesity. Any disturbance in the production of sex hormones and insulin, leads to distortion in the balance between cell proliferation, differentiation and apoptosis. The possible mechanism linking obesity to cancer involves alteration in the level of adipokines and sex hormones. These mediators act as biomarkers for cancer progression and act as targets for cancer therapy and prevention. Interestingly, many anti-cancerous drugs are also beneficial in treating obesity and vice versa. We also reviewed the possible link in the mechanism of few drugs which act both on cancer and obesity. The present review may be important for molecular biologists, oncologists and clinicians treating cancers and also pave the way for better therapeutic options.

Effects of cereal fiber on leptin resistance and sensitivity in C57BL/6J mice fed a high-fat/cholesterol diet

BACKGROUND

Cereal fiber is reported to be associated with obesity and metabolic diseases. However, whether cereal fiber improves leptin resistance and sensitivity remains unclear.

DESIGN

For 24 weeks, 48 male C57BL/6J mice were randomly given a normal chow diet (Chow), high-fat/cholesterol diet (HFD), HFD with 0.8% oat fiber (H-oat) or HFD with 0.8% wheat bran fiber (H-wheat). At the end of feeding period, both the serum insulin and leptin levels were determined by ELISA kits. Western blotting was used to assess the protein expressions of the leptin receptor (LepR) and the leptin-signaling pathway in the adipose tissues.

RESULTS

Our results suggested that mice fed oat or wheat bran fiber exhibited lower body weight, serum lipids, as well as insulin and leptin levels. The two cereal fibers potently increased the protein expressions of LepR in the adipose tissue. In addition, protein expressions of Janus kinase 2 (JAK2) and transcription 3 (STAT3) (induced by LepR), which enhances leptin signaling, were significantly higher and the expression of cytokine signaling-3 (SOCS3), which inhibits leptin signaling, was significantly lower in the two cereal fiber groups than in the HFD group.

CONCLUSION

Taken together, our findings suggest that cereal fiber can improve leptin resistance and sensitivity by the JAK2/STAT3 pathway in C57BL/6J mice fed a HFD; furthermore, oat fiber is more effective in the improvement of leptin sensitivity than wheat bran fiber, in this murine model.

Sleep quality and duration is related with diet and obesity in young adolescent living in Sicily, Southern Italy

The aim of this study was to evaluate the association between sleeping habits, Mediterranean diet pattern, and weight status in an adolescent population. The sample consisted of 1586 individuals aged 11–14 years attending 15 secondary schools of Sicily, Southern Italy. School were randomly selected and the data collected during two school years. Anthropometric data was collected and body composition was assessed by bioelectrical impedance analysis. Demographic information, sleep duration, pediatric daytime sleepiness questionnaire (PDSS), physical activity and dietary habits (including adherence to the Mediterranean Diet using the KIDMED score) were further collected. The mean age was 12±0.7 and about 24% were overweight and obese. An inverse correlation between total sleep time and body mass index (β=−0.829, P=0.021), fat mass (β=−0.526, P=0.025), and waist circumference (β=−0.426, P=0.045) was found. Similar results were found for weekdays sleep time, while an inverse relationship was found with PDSS score. Adherence to Mediterranean Diet was higher in under/normal weight adolescent with a significant linear association between the KIDMED score and the PDSS, weekdays sleep time and total sleep time. Sleep duration was also associated positively with fruits and vegetable intake and negatively with sweet and snack consumption and eating outside habits. Short sleep duration and poor sleep were associated with an increase in BMI and fat mass as well as to unhealthy eating behaviors. These findings suggest that sleep patterns could be a potential target for obesity prevention programs in young adolescence.

Leptin regulates energy metabolism in MCF-7 breast cancer cells

Obesity is known to be a poorer prognosis factor for breast cancer in postmenopausal women. Among the diverse endocrine factors associated to obesity, leptin has received special attention since it promotes breast cancer cell growth and invasiveness, processes which force cells to adapt their metabolism to satisfy the increased demands of energy and biosynthetic intermediates. Taking this into account, our aim was to explore the effects of leptin in the metabolism of MCF-7 breast cancer cells. Polarographic analysis revealed that leptin increased oxygen consumption rate and cellular ATP levels were more dependent on mitochondrial oxidative metabolism in leptin-treated cells compared to the more glycolytic control cells. Experiments with selective inhibitors of glycolysis (2-DG), fatty acid oxidation (etomoxir) or aminoacid deprivation showed that ATP levels were more reliant on fatty acid oxidation. In agreement, levels of key proteins involved in lipid catabolism (FAT/CD36, CPT1, PPARα) and phosphorylation of the energy sensor AMPK were increased by leptin. Regarding glucose, cellular uptake was not affected by leptin, but lactate release was deeply repressed. Analysis of pyruvate dehydrogenase (PDH), lactate dehydrogenase (LDH) and pyruvate carboxylase (PC) together with the pentose-phosphate pathway enzyme glucose-6 phosphate dehydrogenase (G6PDH) revealed that leptin favors the use of glucose for biosynthesis. These results point towards a role of leptin in metabolic reprogramming, consisting of an enhanced use of glucose for biosynthesis and lipids for energy production. This metabolic adaptations induced by leptin may provide benefits for MCF-7 growth and give support to the reverse Warburg effect described in breast cancer.

Plyometric exercise combined with high-intensity interval training improves metabolic abnormalities in young obese females more so than interval training alone

The aim of this study was to compare the effects of 12 weeks of high-intensity interval training (HIIT) with the effects of 12 weeks of plyometric exercise combined with HIIT (P+HIIT) on anthropometric, biochemical, and physical fitness data in young obese females. Sixty-eight participants (age, 16.6 ± 1.3 y; body mass, 82.8 ± 5.0 kg; body fat, 39.4% ± 3.3%; body mass index z score, 2.9 ± 0.4) were assigned to 1 of 3 groups: HIIT (2 blocks per session of 6–8 bouts of 30-s runs at 100% velocity at peak oxygen uptake, with 30-s active recovery between bouts at 50%velocity at peak oxygen uptake (n = 23)); P+HIIT (2 blocks per session of 3 different 15-s plyometric exercises with 15-s passive recoveries, totaling 2 min for each plyometric exercise + the same HIIT program (n = 26)); or control (no exercise (n = 19)). Anthropometric (body mass, body mass index z score, body fat, lean body mass, and waist circumference), biochemical (plasma glucose, insulin, leptin and adiponectin concentrations, leptin/adiponectin ratio, and homeostasis model assessment of insulin resistance (HOMA-IR)), physical fitness (peak oxygen uptake, velocity at peak oxygen uptake, squat jump, and countermovement jump performances), and energy intake data were collected. Both training programs improved the anthropometric, biochemical, and physical fitness variables. However, the P+HIIT program induced greater improvements than did the HIIT program in lean body mass (+3.0% ± 1.7%), plasma glucose and leptin concentrations (–11.0% ± 4.7% and –23.8% ± 5.8%, respectively), plasma leptin/adiponectin ratio (–40.9% ± 10.9%), HOMA-IR (–37.3% ± 6.2%), and squat jump performance (22.2% ± 7.5%). Taken together, these findings suggest that adding plyometric exercises to a HIIT program may be more beneficial than HIIT alone in obese female adolescents.

Beneficial Effects of Evogliptin, a Novel Dipeptidyl Peptidase 4 Inhibitor, on Adiposity with Increased Ppargc1a in White Adipose Tissue in Obese Mice

Although dipeptidyl peptidase 4 (DPP4) is an adipokine known to positively correlate with adiposity, the effects of pharmacological DPP4 inhibition on body composition have not been fully understood. This study was aimed to assess the effects of DPP4 inhibitors on adiposity for the first time in the established obese mice model. The weight loss effects of multiple DPP4 inhibitors were compared after a 4 week treatment in diet-induced obese mice. In addition, a 2 week study was performed to explore and compare the acute effects of evogliptin, a novel DPP4 inhibitor, and exenatide, a glucagon-like peptide-1 (GLP-1) analogue, on whole body composition, energy consumption, various plasma adipokines and gene expression in white adipose tissue (WAT). After the 4 week treatment, weight loss and blood glucose reductions were consistently observed with multiple DPP4 inhibitors. Moreover, after 2-week treatment, evogliptin dose-dependently reduced whole body fat mass while increasing the proportion of smaller adipocytes. However, insulin sensitivity or plasma lipid levels were not significantly altered. In addition to increased active GLP-1 levels by plasma DPP4 inhibition, evogliptin also enhanced basal metabolic rate without reduction in caloric intake, in contrast to exenatide; this finding suggested evogliptin's effects may be mediated by pathways other than via GLP-1. Evogliptin treatment also differentially increased Ppargc1a expression, a key metabolic regulator, in WAT, but not in skeletal muscle and brown adipose tissue. The increased expression of the downstream mitochondrial gene, Cox4i1, was also suggestive of the potential metabolic alteration in WAT by DPP4 inhibitors. We are the first to demonstrate that pharmacological DPP4 inhibition by evogliptin directly causes fat loss in established obese mice. In contradistinction to exenatide, the fat-loss effect of DPP4 inhibitor is partly attributed to enhanced energy expenditure along with metabolic changes in WAT. These results provide insight into the regulation of energy storage in WAT caused by DPP4 inhibition.

Dysregulation of Glucose Homeostasis Following Chronic Exogenous Administration of Leptin in Healthy Sprague-Dawley Rats

INTRODUCTION

Impaired glucose utilization is seen in chronic hyperleptinaemia associated conditions such as obesity and type 2 diabetes mellitus. It is unclear if this impaired glucose utilization is due to the effect of persistent hyperleptinaemia on insulin secretion from the beta cells of pancreas.

AIM

To examine the effects of chronic leptin administration on plasma glucose regulation in rats.

MATERIALS AND METHODS

Glucose challenge curves were plotted for male Sprague-Dawley rats treated with either normal saline (Control; n=8) or subcutaneous leptin injection for 42 days (60 μg/kg body weight/day; n=8). Plasma glucose and plasma insulin levels were measured at 0, 5, 10, 15, 20 and 25 minutes after glucose challenege. Skeletal muscle tissue was collected at the end of a glucose challenge for glucose transporter-4 protein content, insulin receptor and glucose transporter-4 mRNA expression. Data were analysed using repeated measures and one-way ANOVA with post-hoc analysis.

RESULTS

Chronic leptin treatment caused significantly higher fasting insulin level. Post glucose challenge, there was a significant increase in blood glucose levels and insulin level in the leptin treated rats. There was no significant difference in the skeletal muscle glucose transporter-4 content. However, leptin treated rats showed decreased mRNA expression of Insulin Receptor and glucose transporter-4 in the skeletal muscle.

CONCLUSION

Leptin administration for 42 days caused hyperinsulinaemia and decreased the expression of insulin receptors in insulin sensitive tissues leading to the development of an insulin resistance-like state in the rats.

Abnormalities in three-dimensional capillary architecture and imbalance between vascular endothelial growth factor-A and thrombospondin-1 in soleus muscle of ovariectomized rat

Reduced ovarian hormone levels associated with menopause or ovariectomy (OVX) not only result in vascular dysfunction but also lead to structural abnormalities in capillaries. Therefore, the effect of OVX on the three-dimensional (3-D) architecture of capillary networks and the underlying molecular mechanisms were investigated in rat soleus muscle. Seven-week-old female Wistar rats were divided into the OVX and sham-treated (Sham) groups. The OVX group exhibited lower endurance exercise capacity compared to the sham group and resulted in decreased capillary diameter, number of anastomoses and capillary/anastomosis volume in soleus muscle, indicating 3-D structural abnormalities of capillary networks. Furthermore, OVX led to increased concentrations of thrombospondin-1 (TSP-1) protein and a decreased VEGF-A/TSP-1 ratio, an indicator of angio-adaptations, in soleus muscle compared with the Sham group. These results indicate OVX may induce 3-D capillary regression in soleus muscle through an imbalance between VEGF-A and TSP-1 expression, possibly associated with decreased exercise tolerance in ovariectomized rats.

Maternal saturated-fat-rich diet promotes leptin resistance in fetal liver lipid catabolism and programs lipid homeostasis impairments in the liver of rat offspring

We aimed to analyze if an overload of saturated fat in maternal diet induced lipid metabolic impairments in livers from rat fetuses that persist in the offspring and to identify potential mechanisms involving fetal leptin resistance. Female rats were fed either a diet enriched in 25% of saturated fat (SFD rats) or a regular diet (controls). Fetuses of 21days of gestation and offspring of 21 and 140days of age were obtained and plasma and liver were kept for further analysis. Livers from a group of control and SFD fetuses were cultured in the presence or absence of leptin. Leptin or vehicle was administered to control fetuses during the last days of gestation and, on day 21, fetal livers and plasma were obtained. Lipid levels were assessed by thin-layer chromatography and mRNA gene expression of CPT1, ACO and PPARα by RT-PCR. Liver lipid levels were increased and CPT1 and ACO were down-regulated in fetuses and offspring from SFD rats compared to controls. After the culture with leptin, control fetal livers showed increased ACO and CPT1 expression and decreased lipid levels, while fetal livers from SFD rats showed no changes. Fetal administration of leptin induced a decrease in ACO and no changes in CPT1 expression. In summary, our results suggest that a saturated fat overload in maternal diet induces fetal leptin resistance in liver lipid catabolism, which might be contributing to liver lipid alterations that are sustained in the offspring.