Cleavage of the leptin receptor by matrix metalloproteinase-2 promotes leptin resistance and obesity in mice

Exploring the causal relationship between body mass index and keratoconus: a Mendelian randomization study

Background

Despite reports suggesting a link between obesity and keratoconus, the causal relationship is not fully understood.

Methods

We used genome-wide association study (GWAS) data from public databases for a two-sample Mendelian randomization analysis to investigate the causal link between body mass index (BMI) and keratoconus. The primary method was inverse variance weighted (IVW), complemented by different analytical techniques and sensitivity analyses to ensure result robustness. A meta-analysis was also performed to bolster the findings' reliability.

Results

Our study identified a significant causal relationship between BMI and keratoconus. Out of 20 Mendelian randomization (MR) analyses conducted, 9 showed heterogeneity or pleiotropy. Among the 11 analyses that met all three MR assumptions, 4 demonstrated a significant causal difference between BMI and keratoconus, while the remaining 7 showed a positive trend but were not statistically significant. Meta-analysis confirmed a significant causal relationship between BMI and keratoconus.

Conclusion

There is a significant causal relationship between BMI and keratoconus, suggesting that obesity may be a risk factor for keratoconus.

The 40-min HIIT acutely induced bone formation which was likely through the increases in muscle derived interleukin 6 and adiponectin activation: The 16 weeks of HIIT intervention, longitudinal randomized controlled trial

PURPOSE

There is some controversy regarding cytokines released from adipocytes, particularly adiponectin, leptin, and IL6 that regulate bone remodeling. In addition, IL6 is released from muscle contraction, which might have a distinct role in bone remodeling. Hence, this study investigated whether muscle contraction during a session of 40 min of high intensity interval training (40-min HIIT) and after 16 weeks of HIIT (16-wk HIIT) altered the release of those cytokines and bone remodeling in overweight women.

METHODS

In total, 22 overweight, premenopausal women were randomly assigned to either the exercise or the control group. The exercise participants engaged in the 40-min HIIT session at 80-90 % of their heart rate reserve (HRR) three times weekly for 16 weeks, while the control participants performed their routine daily activities. Blood was drawn after overnight fasting and immediately after completing the 40-min HIIT sessions to investigate the association of adiponectin, leptin, IL6, CTX, and P1NP through the acute effect of the 40-min HIIT sessions. This process was repeated after the 16-wk intervention program to observe the training effect of HIIT on cytokines linkage. The bone mineral density (BMD) levels of the distal tibia, femur, and lumbar spine were determined prior to and after the 16-wk intervention using dual-energy X-ray absorptiometry.

RESULTS

The P1NP level increased by 8.29-20.52 % (95 % CI) and by 2.91-15.54 % after completing the first and last bouts of the 40-min HIIT sessions, respectively. In addition, IL6 increased by 13.39-28.03 % (95 % CI), while serum CTX and adiponectin were unaltered from the acute effect of the 40-min HIIT sessions. There was an association between the increases in P1NP and adiponectin (r = 0.682, p = 0.015); however, the increase in P1NP was mostly associated with the increase in IL6 (r = 0.572, p = 0.054) after completing a 40-min HIIT session. After the 16-wk HIIT program, the resting adiponectin level of the exercise participants increased; however, this was associated with neither bone biomarkers nor BMD. The BMDs of the exercise participants were maintained; however, the tibial BMD of the control participants decreased with an increase in the resting CTX level after 16 weeks.

CONCLUSION

Muscle contraction during the 40-min HIIT session elevated the IL6 level, which might have subsequently enhanced bone formation. Furthermore, the association between acute changes in adiponectin and P1NP suggested the possibility of an increase in the sensitivity of the adiponectin receptor in osteoblasts.

Impact of the leptin receptor gene on pig performance and quality traits

The recessive T allele of the missense polymorphism rs709596309 C > T of the leptin receptor gene is associated with intramuscular fat. However, its overall impact on pork production is still partial. In this work, we investigated the all-round effects of the TT genotype on lean growth efficiency and carcass, meat and fat quality using data from an experiment that compared the performance of 48 TT and 48 C- (24 CT and 24 CC) Duroc barrows. The TT pigs were less efficient for lean growth than the C- pigs. Although heavier, their carcasses had less lean content, were shorter and had lighter loins. Apart from increasing marbling and saturated fatty acid content, changes caused by the TT genotype in meat and fat quality are likely not enough to be perceived by consumers. The effect on visual marbling score exceeded that on intramuscular fat content, which suggests a direct influence of the T allele on the pattern of fat distribution in muscle. With current low-protein diets, the T allele is expected to be cost-effective only in niche markets where a very high level of marbling is critical.

A negative feedback loop between TET2 and leptin in adipocyte regulates body weight

Ten-eleven translocation (TET) 2 is an enzyme that catalyzes DNA demethylation to regulate gene expression by oxidizing 5-methylcytosine to 5-hydroxymethylcytosine, functioning as an essential epigenetic regulator in various biological processes. However, the regulation and function of TET2 in adipocytes during obesity are poorly understood. In this study, we demonstrate that leptin, a key adipokine in mammalian energy homeostasis regulation, suppresses adipocyte TET2 levels via JAK2-STAT3 signaling. Adipocyte Tet2 deficiency protects against high-fat diet-induced weight gain by reducing leptin levels and further improving leptin sensitivity in obese male mice. By interacting with C/EBPα, adipocyte TET2 increases the hydroxymethylcytosine levels of the leptin gene promoter, thereby promoting leptin gene expression. A decrease in adipose TET2 is associated with obesity-related hyperleptinemia in humans. Inhibition of TET2 suppresses the production of leptin in mature human adipocytes. Our findings support the existence of a negative feedback loop between TET2 and leptin in adipocytes and reveal a compensatory mechanism for the body to counteract the metabolic dysfunction caused by obesity.

Hibiscus sabdariffa Linn. Extract Increases the mRNA Expression of the Arcuate Nucleus Leptin Receptor and is Predicted in silico as an Anti-obesity Agent

BACKGROUND

Leptin is predominant in regulating body weight by stimulating energy expenditure through its neuronal action in the brain. Moreover, it is projected to adipose tissue and induces adipocyte browning by activating the β3-adrenergic receptor (β3AR). However, the expression of leptin receptor (Lep-R) and β3AR in people with obesity is downregulated.

AIM

We hypothesized that Hibiscus sabdariffa Linn. extract (HSE) would increase hypothalamus arcuate nucleus (ARC) Lep-R and white adipose tissue (WAT) β3AR mRNA expression in DIO rats. This study also analyzed the potency of H. sabdariffa bioactive compounds as activators of Lep-R and β3AR by an in-silico experiment.

METHODS

Twenty-four male Sprague-Dawley rats were divided into four groups: Control (standard food), DIO (high-fat diet), DIO-Hib200 (HFD+HSE 200 mg/kg BW), and DIO-Hib400 (HFD+HSE400 mg/kg BW). HSE was administered orally for five weeks, once a day.

RESULTS

HSE administration significantly (p <0,05) increased the ARC Lep-R expression. The Lee index significantly decreased to the normal range (≤ 310) with p <0,001 for DIO-Hib200 and p <0,01 for DIO-Hib400. Among 39 bioactive compounds, 5-O-caffeoyl shikimic acid exhibited high free binding scores (-8,63) for Lep-R, and myricetin_3_arabinogalactoside had high free binding scores (-9,39) for β3AR. These binding predictions could activate Lep-R and β3AR.

CONCLUSION

This study highlights that HSE could be a potential therapeutic target for obesity by increasing LepR mRNA and leptin sensitivity, enhancing energy expenditure, and reducing obesity.

Leptin antagonism attenuates hypertension and renal injury in an experimental model of autoimmune disease

Systemic lupus erythematosus (SLE) is a chronic autoimmune disorder that is characterized by B- and T-lymphocyte dysfunction and altered cytokine production, including elevated levels of the adipocytokine leptin. Leptin has various immunomodulatory properties, including promoting the expansion of proinflammatory T lymphocytes and the proliferation and survival of B cells. In the present study, we hypothesized that leptin antagonism would improve B- and T-cell dysfunction and attenuate hypertension in an experimental model of SLE, the NZBWF1 mouse. To test this hypothesis, 28-week-old female control and SLE mice were administered 5 mg/kg of murine leptin superantagonist (LA) or vehicle via ip injection every other day for four weeks. Analysis of peripheral blood immune cell populations showed no changes in total CD45R+ B and CD3+ T cell percentages after treatment with LA. However, SLE mice treated with LA had an improved CD4/CD8 ratio and decreased CD3+CD4-CD8- double negative (DN) T cells. Blood pressure was higher in SLE than in control, and treatment with LA decreased blood pressure in SLE mice. Treatment with LA also delayed the onset of albuminuria and decreased glomerulosclerosis in SLE mice. Renal immune cell infiltration was significantly higher in SLE mice as compared with control, but LA treatment was associated with decreased levels of renal CD4+ T cells. In conclusion, these data suggest that leptin plays a pathogenic role in the development of hypertension in SLE, in part, by promoting the expansion of inflammatory DN T cells and the infiltration of T cells into the kidneys.

The Role of Cdc42 in the Insulin and Leptin Pathways Contributing to the Development of Age-Related Obesity

Age-related obesity significantly increases the risk of chronic diseases such as type 2 diabetes, cardiovascular diseases, hypertension, and certain cancers. The insulin-leptin axis is crucial in understanding metabolic disturbances associated with age-related obesity. Rho GTPase Cdc42 is a member of the Rho family of GTPases that participates in many cellular processes including, but not limited to, regulation of actin cytoskeleton, vesicle trafficking, cell polarity, morphology, proliferation, motility, and migration. Cdc42 functions as an integral part of regulating insulin secretion and aging. Some novel roles for Cdc42 have also been recently identified in maintaining glucose metabolism, where Cdc42 is involved in controlling blood glucose levels in metabolically active tissues, including skeletal muscle, adipose tissue, pancreas, etc., which puts this protein in line with other critical regulators of glucose metabolism. Importantly, Cdc42 plays a vital role in cellular processes associated with the insulin and leptin signaling pathways, which are integral elements involved in obesity development if misregulated. Additionally, a change in Cdc42 activity may affect senescence, thus contributing to disorders associated with aging. This review explores the complex relationships among age-associated obesity, the insulin-leptin axis, and the Cdc42 signaling pathway. This article sheds light on the vast molecular web that supports metabolic dysregulation in aging people. In addition, it also discusses the potential therapeutic implications of the Cdc42 pathway to mitigate obesity since some new data suggest that inhibition of Cdc42 using antidiabetic drugs or antioxidants may promote weight loss in overweight or obese patients.

Recent progress in leptin signaling from a structural perspective and its implications for diseases

As a multi-potency cytokine, leptin not only plays a crucial role in controlling weight and energy homeostasis but also participates in the metabolic balance in the human body. Leptin is a small helical protein with a molecular weight of 16 kDa. It can interact with multiple subtypes of its receptors to initiate intracellular signal transduction and exerts physiological effects. Disturbances in leptin signaling may lead to obesity and a variety of metabolic diseases. Leptin was also found to be a critical factor in many diseases of the elderly. In this review, we focus on recent advances in the structural and molecular mechanisms of leptin signaling through its receptors with the aim of a deeper understanding of leptin-related diseases.

Recent progress on action and regulation of anorexigenic adipokine leptin

Organismal energy balance is controlled by inter-tissue communication mediated by the nervous system and hormones, the disruption of which causes metabolic syndrome exemplified by diabetes and obesity. Fat-storing adipose tissue, especially those located in subcutaneous white adipose tissue, secretes leptin in a proportion of fat mass, inhibiting the accumulation of organismal fat by suppressing appetite and promoting energy expenditure. With a prevalence of obesity that exhibits hyperleptinemia, most of the investigation on leptin has been focused on how it works and how it does not, which is expected to be a clue for treating obesity. In contrast, how it is synthesized, transported, and excreted, all of which are relevant to the homeostasis of blood leptin concentration, are not much understood. Of note, acute leptin reduction after hyperleptinemia in the context of obesity exhibited a beneficial effect on obesity and insulin sensitivity, indicating that manipulation of circulating leptin level may provide a therapeutic strategy. Technological advances such as "omics" analysis combined with sophisticated gene-engineered mice studies in the past decade enabled a deeper understanding of leptin's action in more detail. Here, we summarize the updated understanding of the action as well as regulation of leptin and point out the emerging direction of research on leptin.

Roles of Matrix Metalloproteinases and Their Natural Inhibitors in Metabolism: Insights into Health and Disease

Matrix metalloproteinases (MMPs) are a family of zinc-activated peptidases that can be classified into six major classes, including gelatinases, collagenases, stromelysins, matrilysins, membrane type metalloproteinases, and other unclassified MMPs. The activity of MMPs is regulated by natural inhibitors called tissue inhibitors of metalloproteinases (TIMPs). MMPs are involved in a wide range of biological processes, both in normal physiological conditions and pathological states. While some of these functions occur during development, others occur in postnatal life. Although the roles of several MMPs have been extensively studied in cancer and inflammation, their function in metabolism and metabolic diseases have only recently begun to be uncovered, particularly over the last two decades. This review aims to summarize the current knowledge regarding the metabolic roles of metalloproteinases in physiology, with a strong emphasis on adipose tissue homeostasis, and to highlight the consequences of impaired or exacerbated MMP actions in the development of metabolic disorders such as obesity, fatty liver disease, and type 2 diabetes.

Actin related protein 2/3 complex subunit 1 up-regulation in the hypothalamus prevents high-fat diet induced obesity

Obesity is a major health crisis in the modern society. Studies have shown that the consumption of a high-fat diet (HFD) induces hypothalamic inflammation and leptin resistance, which consequently favours body mass gain. Actin related protein 2/3 complex subunit 1 (ARPC1B), an actin-binding protein, is highly expressed in immune cells. Recent studies have shown that ARPC1B has a certain anti-inflammatory effect. While ARPC1B expression is decreased in the hypothalamus of mice fed a HFD, the role of ARPC1B in HFD-induced obesity remains unclear. Thus, we investigated whether ARPC1B up-regulation in the hypothalamic arcuate nucleus (ARC) could inhibit the development of obesity. Herein, ARPC1B overexpression lentiviral particles were stereotaxically injected into the ARC of male C57BL/6J mice (7 weeks old) fed with HFD. Overexpression of ARPC1B in the hypothalamic ARC attenuated HFD-induced ARC inflammation, reduced body-weight gain and feed efficiency. Furthermore, up-regulation of ARC ARPC1B improved the glucose tolerance and reduced subcutaneous/epididymal fat mass accumulation, which decreased the serum total cholesterol, serum triglyceride and leptin levels. In addition, upon ARPC1B overexpression in the hypothalamic ARC, intraperitoneal injection of leptin increased the phosphorylation level of signal transducer and activator of transcription 3 (STAT3), an important transcription factor for leptin's action, in the ARC of obese mice. Accordingly, we suggest that up-regulation of ARPC1B in the hypothalamic ARC may improve the HFD-induced hypothalamic inflammation and leptin resistance. Our findings demonstrate that ARPC1B is a promising target for the treatment of diet-induced obesity.

Recruitment of CTCF to an Fto enhancer is responsible for transgenerational inheritance of BPA-induced obesity

The mechanisms by which environmentally-induced epiphenotypes are transmitted transgenerationally in mammals are poorly understood. Here we show that exposure of pregnant mouse females to bisphenol A (BPA) results in obesity in the F2 progeny due to increased food intake. This epiphenotype can be transmitted up to the F6 generation. Analysis of chromatin accessibility in sperm of the F1-F6 generations reveals alterations at sites containing binding motifs for CCCTC-binding factor (CTCF) at two cis-regulatory elements (CREs) of the Fto gene that correlate with transmission of obesity. These CREs show increased interactions in sperm of obese mice with the Irx3 and Irx5 genes, which are involved in the differentiation of appetite-controlling neurons. Deletion of the CTCF site in Fto results in mice that have normal food intake and fail to become obese when ancestrally exposed to BPA. The results suggest that epigenetic alterations of Fto can lead to the same phenotypes as genetic variants.

Homocysteine causes neuronal leptin resistance and endoplasmic reticulum stress

Abnormally high serum homocysteine levels have been associated with several disorders, including obesity, cardiovascular diseases or neurological diseases. Leptin is an anti-obesity protein and its action is mainly mediated by the activation of its Ob-R receptor in neuronal cells. The inability of leptin to induce activation of its specific signaling pathways, especially under endoplasmic reticulum stress, leads to the leptin resistance observed in obesity. The present study examined the effect of homocysteine on leptin signaling in SH-SY5Y neuroblastoma cells expressing the leptin receptor Ob-Rb. Phosphorylation of the signal transducer and activator of transcription (STAT3) and leptin-induced STAT3 transcriptional activity were significantly inhibited by homocysteine treatment. These effects may be specific to homocysteine and to the leptin pathway, as other homocysteine-related compounds, namely methionine and cysteine, have weak effect on leptin-induced inhibition of STAT3 phosphorylation, and homocysteine has no impact on IL-6-induced activation of STAT3. The direct effect of homocysteine on leptin-induced Ob-R activation, analyzed by Ob-R BRET biosensor to monitor Ob-R oligomerization and conformational change, suggested that homocysteine treatment does not affect early events of leptin-induced Ob-R activation. Instead, we found that, unlike methionine or cysteine, homocysteine increases the expression of the endoplasmic reticulum (ER) stress response gene, a homocysteine-sensitive ER resident protein. These results suggest that homocysteine may induce neuronal resistance to leptin by suppressing STAT3 phosphorylation downstream of the leptin receptor via ER stress.

A novel anti-obesity mechanism for liraglutide by improving adipose tissue leptin resistance in high-fat diet-fed obese mice

Liraglutide has been approved for the treatment of obesity in the past few years. Both oxidative stress and leptin resistance are the critical drivers of obesity. The present study investigated the mechanism of liraglutide protection against obesity by ameliorating leptin resistance and oxidative stress. Male C57BL/6J mice were fed a high-fat diet (HFD) and subcutaneously injected with 200 μg/kg/d liraglutide for 20 weeks. Body weight, fat mass, serum levels of leptin, insulin, and superoxide dismutase (SOD) activities were measured. In addition, glucose and insulin tolerance tests were performed. The expressions of leptin, its signaling genes, and antioxidant enzymes were detected using RT-qPCR and western blot methods in liver and white adipose tissue (WAT) of mice. The results depicted that liraglutide treatment significantly slowed weight gain of body, reduced the fat mass, ameliorated glucose and lipid metabolism, and hepatic steatosis in HFD-fed obese mice. Further study demonstrated that liraglutide treatment resulted in decreased serum levels and the transcript levels of leptin as well as leptin signaling inhibitory regulators. However, it increased leptin receptor expression and the phosphorylation of signal transducer and activator of transcription 3 (p-STAT3) in WAT (p < 0.05). In addition, the antioxidant enzyme expression was elevated in both liver and WAT of liraglutide-treated mice (p < 0.05). In conclusion, liraglutide conspicuously prevented obesity and ameliorated glucose and lipid metabolism in obese mice through a novel mechanism that improves peripheral leptin resistance in WAT and enhance the antioxidant enzyme expression in both liver and WAT.

Endothelial Glycocalyx

The glycocalyx is a polysaccharide structure that protrudes from the body of a cell. It is primarily conformed of glycoproteins and proteoglycans, which provide communication, electrostatic charge, ionic buffering, permeability, and mechanosensation-mechanotransduction capabilities to cells. In blood vessels, the endothelial glycocalyx that projects into the vascular lumen separates the vascular wall from the circulating blood. Such a physical location allows a number of its components, including sialic acid, glypican-1, heparan sulfate, and hyaluronan, to participate in the mechanosensation-mechanotransduction of blood flow-dependent shear stress, which results in the synthesis of nitric oxide and flow-mediated vasodilation. The endothelial glycocalyx also participates in the regulation of vascular permeability and the modulation of inflammatory responses, including the processes of leukocyte rolling and extravasation. Its structural architecture and negative charge work to prevent macromolecules greater than approximately 70 kDa and cationic molecules from binding and flowing out of the vasculature. This also prevents the extravasation of pathogens such as bacteria and virus, as well as that of tumor cells. Due to its constant exposure to shear and circulating enzymes such as neuraminidase, heparanase, hyaluronidase, and matrix metalloproteinases, the endothelial glycocalyx is in a continuous process of degradation and renovation. A balance favoring degradation is associated with a variety of pathologies including atherosclerosis, hypertension, vascular aging, metastatic cancer, and diabetic vasculopathies. Consequently, ongoing research efforts are focused on deciphering the mechanisms that promote glycocalyx degradation or limit its syntheses, as well as on therapeutic approaches to improve glycocalyx integrity with the goal of reducing vascular disease. © 2022 American Physiological Society. Compr Physiol 12: 1-31, 2022.

Impaired Brain Satiety Responses After Weight Loss in Children With Obesity

CONTEXT

Obesity interventions often result in increased motivation to eat.

OBJECTIVE

We investigated relationships between obesity outcomes and changes in brain activation by visual food cues and hormone levels in response to obesity intervention by family-based behavioral treatment (FBT).

METHODS

Neuroimaging and hormone assessments were conducted before and after 24-week FBT intervention in children with obesity (OB, n = 28), or children of healthy weight without intervention (HW, n = 17), all 9- to 11-year-old boys and girls. We evaluated meal-induced changes in neural activation to high- vs low-calorie food cues across appetite-processing brain regions and gut hormones.

RESULTS

Among children with OB who underwent FBT, greater declines of BMI z-score were associated with lesser reductions after the FBT intervention in meal-induced changes in neural activation to high- vs low-calorie food cues across appetite-processing brain regions (P < 0.05), and the slope of relationship was significantly different compared with children of HW. In children with OB, less reduction in brain responses to a meal from before to after FBT was associated with greater meal-induced reduction in ghrelin and increased meal-induced stimulation in peptide YY and glucagon-like peptide-1 (all P < 0.05).

CONCLUSION

In response to FBT, adaptations of central satiety responses and peripheral satiety-regulating hormones were noted. After weight loss, changes of peripheral hormone secretion support weight loss, but there was a weaker central satiety response. The findings suggest that even when peripheral satiety responses by gut hormones are intact, the central regulation of satiety is disturbed in children with OB who significantly improve their weight status during FBT, which could favor future weight regain.

Anti-Obesity Effect of Rice Bran Extract on High-Fat Diet-Induced Obese Mice

Obesity involving adipose tissue growth and development are associated with angiogenesis and extracellular matrix remodeling. Rice bran has antioxidant and cardioprotective properties, and can act as a food supplement with potential health benefits, such as lowering blood pressure, hepatic steatosis, and inflammation. Therefore, we hypothesized that rice bran extract (RBE) can regulate adipose tissue growth and obesity. Male Institute of Cancer Research mice were fed with a high-fat diet (HFD) for 8 weeks and then supplemented with 220 and 1,100 mg/kg/d RBE while the low-fat diet group (control) were not. In addition to body weight, adipose tissue mass, and vessel density, we evaluated the mRNA expression of angiogenic factors such as matrix metalloproteinases, Mmp-2, Mmp-9, and the vascular endothelial growth factor (Vegf) in visceral and subcutaneous adipose tissues using real-time polymerase chain reaction. Administration of RBE to HFD-induced obese mice reduced the body weight and adipose tissue mass compared with untreated mice. It also decreased blood vessel density in the adipose tissue. Furthermore, RBE downregulated Vegf and Mmp-2 mRNA levels in visceral fat tissue. These results demonstrate that RBE, at high concentrations, significantly reduces adipose tissue mass and prevents obesity development in HFD-induced obese mice, which might be partly mediated via an anti-angiogenic mechanism.

Multistage targeting and dual inhibiting strategies based on bioengineered tumor matrix microenvironment‐mediated protein nanocages for enhancing cancer biotherapy

Regulation of the apoptotic pathway plays a critical role in inducing tumor cell death and circumventing drug resistance. Survivin protein is the strongest inhibitor of apoptosis found so far. It is highly expressed in several cancers and is a promising target for cancer therapy. However, clinical applications are limited by incomplete inhibition of survivin expression. Here, we present a novel strategy that extended the release of YM155 (an effective survivin inhibitor that works by inhibiting the activity of survivin promoter) and TATm‐survivin (T34A) (TmSm) protein (survivin protein mutant with penetrating peptide, a potential anticancer protein therapeutic) via tumor matrix microenvironment‐mediated ferritin heavy chain nanocages (FTH1 NCs), enabling significant inhibition of survivin activity at both transcript and protein levels. FTS (FTH1‐matrix metalloproteinase‐2‐TmSm)/YM155 NC synthesis was easily scaled up, and these NCs could sequentially release TmSm protein through matrix metalloproteinase‐2 and promote YM155 to enter the nucleus via transferrin receptor 1 (TfR1) binding, which increased the cytotoxicity and apoptosis of Capan‐2 and A549 cells compared to that with individual drugs. Moreover, FTS/YM155 NCs enhanced drug accumulation at tumor sites and had a higher tumor inhibition rate (88.86%) than the compounds alone in A549 tumor‐bearing mice. In addition, FTS/YM155 NCs exerted significant survivin downregulation (4.43‐fold) and caspase‐3 upregulation (4.31‐fold) and showed better therapeutic outcomes without inducing organ injury, which highlights their promising future clinical application in precision therapy. This tumor microenvironment‐responsive platform could be harnessed to develop an effective therapy via multilevel inhibition of cancer targets.

Histone deacetylase 6 inhibition restores leptin sensitivity and reduces obesity

The adipose tissue-derived hormone leptin can drive decreases in food intake while increasing energy expenditure. In diet-induced obesity, circulating leptin levels rise proportionally to adiposity. Despite this hyperleptinemia, rodents and humans with obesity maintain increased adiposity and are resistant to leptin's actions. Here we show that inhibitors of the cytosolic enzyme histone deacetylase 6 (HDAC6) act as potent leptin sensitizers and anti-obesity agents in diet-induced obese mice. Specifically, HDAC6 inhibitors, such as tubastatin A, reduce food intake, fat mass, hepatic steatosis and improve systemic glucose homeostasis in an HDAC6-dependent manner. Mechanistically, peripheral, but not central, inhibition of HDAC6 confers central leptin sensitivity. Additionally, the anti-obesity effect of tubastatin A is attenuated in animals with a defective central leptin-melanocortin circuitry, including db/db and MC4R knockout mice. Our results suggest the existence of an HDAC6-regulated adipokine that serves as a leptin-sensitizing agent and reveals HDAC6 as a potential target for the treatment of obesity.

Digestive Enzyme Activity and Protein Degradation in Plasma of Heart Failure Patients

Introduction

Heart failure is associated with degradation of cell functions and extracellular matrix proteins, but the trigger mechanisms are uncertain. Our recent evidence shows that active digestive enzymes can leak out of the small intestine into the systemic circulation and cause cell dysfunctions and organ failure.

Methods

Accordingly, we investigated in morning fasting plasma of heart failure (HF) patients the presence of pancreatic trypsin, a major enzyme responsible for digestion.

Results

Western analysis shows that trypsin in plasma is significantly elevated in HF compared to matched controls and their concentrations correlate with the cardiac dysfunction biomarker BNP and inflammatory biomarkers CRP and TNF-α. The plasma trypsin levels in HF are accompanied by elevated pancreatic lipase concentrations. The trypsin has a significantly elevated activity as determined by substrate cleavage. Mass spectrometry shows that the number of plasma proteins in the HF patients is similar to controls while the number of peptides was increased about 20% in HF patients. The peptides are derived from extracellular and intracellular protein sources and exhibit cleavage sites by trypsin as well as other degrading proteases (data are available via ProteomeXchange with identifier PXD026332).

Connclusions

These results provide the first evidence that active digestive enzymes leak into the systemic circulation and may participate in myocardial cell dysfunctions and tissue destruction in HF patients.

Conclusions

These results provide the first evidence that active digestive enzymes leak into the systemic circulation and may participate in myocardial cell dysfunctions and tissue destruction in HF patients.

Supplementary Information

The online version contains supplementary material available at 10.1007/s12195-021-00693-w.

Apelin expression deficiency in mice contributes to vascular stiffening by extracellular matrix remodeling of the aortic wall

Numerous recent studies have shown that in the continuum of cardiovascular diseases, the measurement of arterial stiffness has powerful predictive value in cardiovascular risk and mortality and that this value is independent of other conventional risk factors, such as age, cholesterol levels, diabetes, smoking, or average blood pressure. Vascular stiffening is often the main cause of arterial hypertension (AHT), which is common in the presence of obesity. However, the mechanisms leading to vascular stiffening, as well as preventive factors, remain unclear. The aim of the present study was to investigate the consequences of apelin deficiency on the vascular stiffening and wall remodeling of aorta in mice. This factor freed by visceral adipose tissue, is known for its homeostasic role in lipid and vascular metabolisms, or again in inflammation. We compared the level of metabolic markers, inflammation of white adipose tissue (WAT), and aortic wall remodeling from functional and structural approaches in apelin-deficient and wild-type (WT) mice. Apelin-deficient mice were generated by knockout of the apelin gene (APL-KO). From 8 mice by groups, aortic stiffness was analyzed by pulse wave velocity measurements and by characterizations of collagen and elastic fibers. Mann-Whitney statistical test determined the significant data (p < 5%) between groups. The APL-KO mice developed inflammation, which was associated with significant remodeling of visceral WAT, such as neutrophil elastase and cathepsin S expressions. In vitro, cathepsin S activity was detected in conditioned medium prepared from adipose tissue of the APL-KO mice, and cathepsin S activity induced high fragmentations of elastic fiber of wild-type aorta, suggesting that the WAT secretome could play a major role in vascular stiffening. In vivo, remodeling of the extracellular matrix (ECM), such as collagen accumulation and elastolysis, was observed in the aortic walls of the APL-KO mice, with the latter associated with high cathepsin S activity. In addition, pulse wave velocity (PWV) and AHT were increased in the APL-KO mice. The latter could explain aortic wall remodeling in the APL-KO mice. The absence of apelin expression, particularly in WAT, modified the adipocyte secretome and facilitated remodeling of the ECM of the aortic wall. Thus, elastolysis of elastic fibers and collagen accumulation contributed to vascular stiffening and AHT. Therefore, apelin expression could be a major element to preserve vascular homeostasis.

A targeted proteomics investigation of the obesity paradox in venous thromboembolism

The obesity paradox, the controversial finding that obesity promotes disease development but protects against sequelae in patients, has been observed in venous thromboembolism (VTE). The aim of this investigation was to identify a body mass-related proteomic signature in VTE patients and to evaluate whether this signature mediates the obesity paradox in VTE patients. Data from the Genotyping and Molecular Phenotyping in Venous ThromboEmbolism Project, a prospective cohort study of 693 VTE patients, were analyzed. A combined end point of recurrent VTE or all-cause death was used. Relative quantification of 444 proteins was performed using high-throughput targeted proteomics technology. Measurements were performed in samples collected during the acute VTE event and at 12-month follow-up. An 11-protein signature (CLEC4C, FABP4, FLT3LG, IL-17C, LEP, LYVE1, MASP1, ST2, THBS2, THBS4, TSLP) for body mass in VTE patients was identified. The signature did not significantly mediate the obesity paradox (change in hazard ratio [HR]: 0.04; likelihood ratio test of nested models = 7.7; P = .74), but its main constituent protein, leptin, was inversely associated with recurrent VTE or death (adjusted HR [95% confidence interval] per standard deviation increase: 0.66 [0.46-0.94]). This relationship was significantly (P = .007) modified by markers of leptin resistance (ie, high body mass index and high circulating matrix metalloproteinase-2 levels). Although the signature did not substantially explain the obesity paradox, leptin appears to be protective against disease recurrence and death in VTE patients. This protective effect was abrogated under conditions of leptin resistance and hence was unrelated to the obesity paradox.

Impaired Leptin Signalling in Obesity: Is Leptin a New Thermolipokine?

Leptin is a principal adipose-derived hormone mostly implicated in the regulation of energy balance through the activation of anorexigenic neuronal pathways. Comprehensive studies have established that the maintenance of certain concentrations of circulating leptin is essential to avoid an imbalance in nutrient intake. Indeed, genetic modifications of the leptin/leptin receptor axis and the obesogenic environment may induce changes in leptin levels or action in a manner that accelerates metabolic dysfunctions, resulting in a hyperphagic status and adipose tissue expansion. As a result, a vicious cycle begins wherein hyperleptinaemia and leptin resistance occur, in turn leading to increased food intake and fat enlargement, which is followed by leptin overproduction. In addition, in the context of obesity, a defective thermoregulatory response is associated with impaired leptin signalling overall within the ventromedial nucleus of the hypothalamus. These recent findings highlight the role of leptin in the regulation of adaptive thermogenesis, thus suggesting leptin to be potentially considered as a new thermolipokine. This review provides new insight into the link between obesity, hyperleptinaemia, leptin resistance and leptin deficiency, focusing on the ability to restore leptin sensitiveness by way of enhanced thermogenic responses and highlighting novel anti-obesity therapeutic strategies.

The pleiotropic roles of leptin in metabolism, immunity, and cancer

The discovery of the archetypal adipocytokine leptin and how it regulates energy homeostasis have represented breakthroughs in our understanding of the endocrine function of the adipose tissue and the biological determinants of human obesity. Investigations on leptin have also been instrumental in identifying physio-pathological connections between metabolic regulation and multiple immunological functions. For example, the description of the promoting activities of leptin on inflammation and cell proliferation have recognized the detrimental effects of leptin in connecting dysmetabolic conditions with cancer and with onset and/or progression of autoimmune disease. Here we review the multiple biological functions and complex framework of operations of leptin, discussing why and how the pleiotropic activities of this adipocytokine still pose major hurdles in the development of effective leptin-based therapeutic opportunities for different clinical conditions.

SIRT1 promotes lipid metabolism and mitochondrial biogenesis in adipocytes and coordinates adipogenesis by targeting key enzymatic pathways

The NAD+-dependent deacetylase SIRT1 controls key metabolic functions by deacetylating target proteins and strategies that promote SIRT1 function such as SIRT1 overexpression or NAD+ boosters alleviate metabolic complications. We previously reported that SIRT1-depletion in 3T3-L1 preadipocytes led to C-Myc activation, adipocyte hyperplasia, and dysregulated adipocyte metabolism. Here, we characterized SIRT1-depleted adipocytes by quantitative mass spectrometry-based proteomics, gene-expression and biochemical analyses, and mitochondrial studies. We found that SIRT1 promoted mitochondrial biogenesis and respiration in adipocytes and expression of molecules like leptin, adiponectin, matrix metalloproteinases, lipocalin 2, and thyroid responsive protein was SIRT1-dependent. Independent validation of the proteomics dataset uncovered SIRT1-dependence of SREBF1c and PPARα signaling in adipocytes. SIRT1 promoted nicotinamide mononucleotide acetyltransferase 2 (NMNAT2) expression during 3T3-L1 differentiation and constitutively repressed NMNAT1 and 3 levels. Supplementing preadipocytes with the NAD+ booster nicotinamide mononucleotide (NMN) during differentiation increased expression levels of leptin, SIRT1, and PGC-1α and its transcriptional targets, and reduced levels of pro-fibrotic collagens (Col6A1 and Col6A3) in a SIRT1-dependent manner. Investigating the metabolic impact of the functional interaction of SIRT1 with SREBF1c and PPARα and insights into how NAD+ metabolism modulates adipocyte function could potentially lead to new avenues in developing therapeutics for obesity complications.

Oral intake of Lactobacillus plantarum L-14 extract alleviates TLR2- and AMPK-mediated obesity-associated disorders in high-fat-diet-induced obese C57BL/6J mice

OBJECTIVES

Whether periodic oral intake of postbiotics positively affects weight regulation and prevents obesity-associated diseases in vivo is unclear. This study evaluated the action mechanism of Lactobacillus plantarum L-14 (KTCT13497BP) extract and the effects of its periodic oral intake in a high-fat-diet (HFD) mouse model.

MATERIALS AND METHODS

Mouse pre-adipocyte 3T3-L1 cells and human bone marrow mesenchymal stem cells (hBM-MSC) were treated with L-14 extract every 2 days during adipogenic differentiation, and the mechanism underlying anti-adipogenic effects was analysed at cellular and molecular levels. L-14 extract was orally administrated to HFD-feeding C57BL/6J mice every 2 days for 7 weeks. White adipose tissue was collected and weighed, and liver and blood serum were analysed. The anti-adipogenic mechanism of exopolysaccharide (EPS) isolated from L-14 extract was also analysed using Toll-like receptor 2 (TLR2) inhibitor C29.

RESULTS

L-14 extract inhibited 3T3-L1 and hBM-MSC differentiation into mature adipocytes by upregulating AMPK signalling pathway in the early stage of adipogenic differentiation. The weight of the HFD + L-14 group (31.51 ± 1.96 g) was significantly different from that of the HFD group (35.14 ± 3.18 g). L-14 extract also significantly decreased the serum triacylglycerol/high-density lipoprotein cholesterol ratio (an insulin resistance marker) and steatohepatitis. In addition, EPS activated the AMPK signalling pathway by interacting with TLR2, consequently inhibiting adipogenesis.

CONCLUSIONS

EPS from L-14 extract inhibits adipogenesis via TLR2 and AMPK signalling pathways, and oral intake of L-14 extract improves obesity and obesity-associated diseases in vivo. Therefore, EPS can be used to prevent and treat obesity and metabolic disorders.

Regulation of Metabolic Health by an "Olfactory-Hypothalamic Axis" and Its Possible Implications for the Development of Therapeutic Approaches for Obesity and T2D

The olfactory system is responsible for the reception, integration and interpretation of odors. However, in the last years, it has been discovered that the olfactory perception of food can rapidly modulate the activity of hypothalamic neurons involved in the regulation of energy balance. Conversely, the hormonal signals derived from changes in the metabolic status of the body can also change the sensitivity of the olfactory system, suggesting that the bidirectional relationship established between the olfactory and the hypothalamic systems is key for the maintenance of metabolic homeostasis. In the first part of this review, we describe the possible mechanisms and anatomical pathways involved in the modulation of energy balance regulated by the olfactory system. Hence, we propose a model to explain its implication in the maintenance of the metabolic homeostasis of the organism. In the second part, we discuss how the olfactory system could be involved in the development of metabolic diseases such as obesity and type two diabetes and, finally, we propose the use of intranasal therapies aimed to regulate and improve the activity of the olfactory system that in turn will be able to control the neuronal activity of hypothalamic centers to prevent or ameliorate metabolic diseases.

The complex role of adipokines in obesity, inflammation, and autoimmunity

The global obesity epidemic is a major contributor to chronic disease and disability in the world today. Since the discovery of leptin in 1994, a multitude of studies have characterized the pathological changes that occur within adipose tissue in the obese state. One significant change is the dysregulation of adipokine production. Adipokines are an indispensable link between metabolism and optimal immune system function; however, their dysregulation in obesity contributes to chronic low-grade inflammation and disease pathology. Herein, I will highlight current knowledge on adipokine structure and physiological function, and focus on the known roles of these factors in the modulation of the immune response. I will also discuss adipokines in rheumatic and autoimmune diseases.

Leptin and the GA genotype of rs2167270 of the LEP gene increase the risk of prediabetes

Prediabetes is a precursor stage that frequently develops to definitive type 2 diabetes mellitus (T2DM). Therefore, identifying individuals with prediabetes can allow for early intervention measures that delay or prevent disease progression to T2DM. Several biochemical changes appear to be associated with prediabetes, including an increase in the serum levels of leptin. In Jordan, this association has not been previously investigated. In the present study, the serum levels of leptin were measured in 122 prediabetes subjects and 122 controls. Furthermore, the genotypes of three single nucleotide polymorphisms in the LEP gene (rs7799039, rs2167270 and rs791620) were investigated for their association with prediabetes using PCR-restriction fragment length polymorphism. The results revealed a significant increase in serum leptin levels in the prediabetes group. It was also shown that the GA genotype and the A allele of rs2167270 were significantly associated with an increased risk of prediabetes (P<0.05). These findings were shown to be independent of body mass index, waist circumference and serum glucose levels. To the best of our knowledge, the present study is the first in Jordan to have reported an association between serum leptin levels and the GA genotype of rs2167270 with an increased risk of prediabetes, identified both in the univariate and multivariate models.

Intervertebral Disc and Adipokine Leptin-Loves Me, Loves Me Not

Leptin—the most famous adipose tissue-secreted hormone—in the human body is mostly observed in a negative connotation, as the hormone level increases with the accumulation of body fat. Nowadays, fatness is becoming another normal body shape. Fatness is burdened with numerous illnesses—including low back pain and degenerative disease of lumbar intervertebral disc (IVD). IVD degeneration and IVD inflammation are two indiscerptible phenomena. Irrespective of the underlying pathophysiological background (trauma, obesity, nutrient deficiency), the inflammation is crucial in triggering IVD degeneration. Leptin is usually depicted as a proinflammatory adipokine. Many studies aimed at explaining the role of leptin in IVD degeneration, though mostly in in vitro and on animal models, confirmed leptin’s “bad reputation”. However, several studies found that leptin might have protective role in IVD metabolism. This review examines the current literature on the metabolic role of different depots of adipose tissue, with focus on leptin, in pathogenesis of IVD degeneration.

Dysregulated appetitive leptin signaling in male rodent offspring from post-bariatric dams

Bariatric surgery produces significant positive benefits to recipients such as resolution of various obesity-related comorbidities, including improved reproductive function. Females of childbearing age seek bariatric surgical remedies to improve their chance of successful pregnancy; however, limited knowledge exists on the impact of surgical weight loss to subsequently born offspring.

We previously reported that circulating leptin levels were reduced in pregnant females having previously received vertical sleeve gastrectomy (VSG) in comparison to control dams having received Sham surgery. Furthermore, the levels of leptin receptors in the VSG placenta were also reduced in comparison to controls in. These data suggest there may be a significant difference in leptin signaling during pregnancy that may produce an altered developmental environment for the offspring.

Here, we investigate the adult offspring of dams having received VSG or Sham-VSG prior to pregnancy. Endogenous fasting plasma leptin levels were not different between Sham and VSG offspring. Fasting leptin receptor mRNA in the medial basal hypothalamus (MBH) was elevated in VSG offspring in comparison to Sham. Intraperitoneal administration of exogenous leptin produced reductions in acute food intake in male Sham offspring, but did not reduce food intake at any time point measured in male VSG offspring. Using Western blot, we identified elevated pSTAT3 and pSTAT3/STAT3 ratios in the MBH of post-VSG offspring in comparison to controls. Using immunohistochemistry, we found an increased number of pSTAT positive cells in the arcuate nucleus in the Sham offspring in comparison to VSG. In contrast, within the paraventricular and ventromedial hypothalamic nuclei the VSG offspring had elevated numbers of pSTAT-positive cells in comparison to controls. Collectively, these data support our hypothesis that leptin signaling is dysregulated in VSG offspring and may be partially responsible for the long-term impact of maternal bariatric surgery on the metabolic health of offspring.

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Pregnancies following bariatric surgeries have reduced circulating leptin and increased leptin receptors in placenta.

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Offspring of dams having previously received bariatric surgery have altered growth trajectories during postnatal life.

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The male offspring experience have elevated expression of hypothalamic leptin receptors.

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The bariatric offspring are non-responsive to the anorexigenic effects of exogenous leptin administration.

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pSTAT in the hypothalamus of post-bariatric offspring is elevated without a change in food intake.

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Leptin signaling may be responsible for long-term metabolic changes in post-bariatric offspring.

Different roles of matrix metalloproteinase 2 in osteolysis of skeletal dysplasia and bone metastasis (Review)

Matrix metalloproteinase 2 (MMP2) is a well-characterized protein that is indispensable for extracellular matrix remodeling and other pathological processes, such as tumor progression and skeletal dysplasia. Excessive activation of MMP2 promotes osteolytic metastasis and bone destruction in late-stage cancers, while its loss-of-function mutations result in the decreased bone mineralization and generalized osteolysis occurring progressively in skeletal developmental disorders, particularly in multicentric osteolysis, nodulosis and arthropathy (MONA). Either upregulation or downregulation of MMP2 activity can result in the same osteolytic effects. Thus, different functions of MMP2 have been recently identified that could explain this observation. While MMP2 can degrade bone matrix, facilitate osteoclastogenesis and amplify various signaling pathways that enhance osteolysis in bone metastasis, its role in maintaining the number of bone cells, supporting osteocytic canalicular network formation and suppressing leptin-mediated inhibition of bone formation has been implicated in osteolytic disorders caused by MMP2 deficiency. Furthermore, the proangiogenic activity of MMP2 is one of the potential mechanisms that are associated with both pathological situations. In the present article, the latest research on MMP2 in bone homeostasis is reviewed and the mechanisms underlying the role of this protein in skeletal metastasis and developmental osteolysis are discussed.

CB1R regulates soluble leptin receptor levels via CHOP, contributing to hepatic leptin resistance

The soluble isoform of leptin receptor (sOb-R), secreted by the liver, regulates leptin bioavailability and bioactivity. Its reduced levels in diet-induced obesity (DIO) contribute to hyperleptinemia and leptin resistance, effects that are regulated by the endocannabinoid (eCB)/CB₁R system. Here we show that pharmacological activation/blockade and genetic overexpression/deletion of hepatic CB₁R modulates sOb-R levels and hepatic leptin resistance. Interestingly, peripheral CB₁R blockade failed to reverse DIO-induced reduction of sOb-R levels, increased fat mass and dyslipidemia, and hepatic steatosis in mice lacking C/EBP homologous protein (CHOP), whereas direct activation of CB₁R in wild-type hepatocytes reduced sOb-R levels in a CHOP-dependent manner. Moreover, CHOP stimulation increased sOb-R expression and release via a direct regulation of its promoter, while CHOP deletion reduced leptin sensitivity. Our findings highlight a novel molecular aspect by which the hepatic eCB/CB₁R system is involved in the development of hepatic leptin resistance and in the regulation of sOb-R levels via CHOP.

When the human body has stored enough energy from food, it releases a hormone called leptin that travels to the brain and stops feelings of hunger. This hormone moves through the bloodstream and can affect other organs, such as the liver, which also help control our body’s energy levels. Most people with obesity have very high levels of leptin in their blood, but are resistant to its effects and will therefore continue to feel hungry despite having stored enough energy.

One of the proteins that controls the levels of leptin is a receptor called sOb-R, which is released by the liver and binds to leptin as it travels in the blood. Individuals with high levels of this receptor often have less free leptin in their bloodstream and a lower body weight. Another protein that helps the body to regulate its energy levels is the cannabinoid-1 receptor, or CB1R for short. In people with obesity, this receptor is overactive and has been shown to contribute to leptin resistance, which is when the brain becomes less receptive to leptin. Previous work in mice showed that blocking CB1R reduced the levels of leptin and allowed mice to react to this hormone normally again, but it remained unclear whether CB1R affects how other organs, such as the liver, respond to leptin.

To answer this question, Drori et al. blocked the CB1R receptor in the liver of mice eating a high-fat diet, either by using a drug or by deleting the gene that codes for this protein. This caused mice to have higher levels of sOb-R circulating in their bloodstream. Further experiments showed that this change in sOb-R was caused by the levels of a protein called CHOP increasing in the liver when CB1R was blocked. Drori et al. found that inhibiting CB1R caused these obese mice to lose weight and have healthier, less fatty livers as a result of their livers no longer being resistant to the effects of leptin.

Scientists, doctors and pharmaceutical companies are trying to develop new strategies to combat obesity. The results from these experiments suggest that blocking CB1R in the liver could allow this organ to react to leptin appropriately again. Drugs blocking CB1R, including the one used in this study, will be tested in clinical trials and could provide a new approach for treating obesity.

The impact of antibiotics on the metabolic status of obese adults without bacterial infection: a systematic review and meta-analysis

Background

The gut microbiota is involved in the pathophysiology of obesity. It is known that oral antibiotics manipulate the gut microbiota; however, the impact on host metabolism of obese adults without bacterial infection has not been systematically summarized.

Methods

We searched for randomized, placebo-controlled trials that investigated the effects of oral antibiotics on the metabolic status in obese adults via Medline, EMBASE, and the Cochrane Library. Primary outcomes were homeostasis model assessment of insulin resistance (HOMA-IR), body weight, and rate of diarrhea. Additional outcomes included fasting plasma glucose (FPG), plasma glucagon-like peptide-1 (GLP-1), waist circumference, fecal short-chain fatty acid (SCFA) levels, and all adverse events. We assessed the certainty of evidence based on Grading of Recommendations, Assessment, Development and Evaluations.

Results

Among 1,762 articles screened, four studies were eligible for quantitative analysis, two of which were applied to meta-analysis. Oral antibiotics had low influence on HOMA-IR [mean difference (MD) 0.09 (95% CI: -0.96 to 1.13)], body weight [MD 4.1 kg (95% CI: -23.77 to 31.97)], FPG [MD -0.12 mmol/L (95% CI: -0.47 to 0.23)], and GLP-1 [MD 0.20 pmol/L (95% CI: -2.36 to 2.76)] compared to placebo. Antibiotics treatment altered fecal acetate and butyrate levels, but resulted in little difference in propionate levels [MD -13.60 µmol/g (95% CI: -22.43 to -4.77), MD -7.60 µmol/g (-10.97 to -4.23), MD -1.10 µmol/g (95% CI: -4.18 to 1.98), respectively]. Several adverse events, such as sun sensitivity and gastrointestinal discomfort, were reported following antibiotics treatment, but no diarrhea. The certainty of evidence for most outcomes was very low to low, except for fecal SCFAs.

Conclusions

Our results indicate that oral antibiotics treatment is insufficient to ameliorate metabolic parameters in obese adults, suggesting that oral antibiotics treatment may not qualify as a therapeutic approach for obesity.

Discriminatory Capacity of Anthropometric Indices for Cardiovascular Disease in Adults: A Systematic Review and Meta-Analysis

INTRODUCTION

Obesity is one of the main risk factors for cardiovascular disease (CVD) and cardiometabolic disease (CMD). Many studies have developed cutoff points of anthropometric indices for predicting these diseases. The aim of this systematic review was to differentiate the screening potential of body mass index (BMI), waist circumference (WC), and waist-to-hip ratio (WHR) for adult CVD risk.

METHODS

We used relevant key words to search electronic databases to identify studies published up to 2019 that used receiver operating characteristic (ROC) curves for assessing the cut-off points of anthropometric indices. We used a random-effects model to pool study results and assessed between-study heterogeneity by using the I² statistic and Cochran's Q test.

RESULTS

This meta-analysis included 38 cross-sectional and 2 cohort studies with 105 to 137,256 participants aged 18 or older. The pooled area under the ROC curve (AUC) value for BMI was 0.66 (95% CI, 0.63-0.69) in both men and women. The pooled AUC values for WC were 0.69 (95% CI, 0.67-0.70) in men and 0.69 (95% CI, 0.64-0.74) in women, and the pooled AUC values for WHR were 0.69 (95% CI, 0.66-0.73) in men and 0.71 (95% CI, 0.68-0.73) in women.

CONCLUSION

Our findings indicated a slight difference between AUC values of these anthropometric indices. However, indices of abdominal obesity, especially WHR, can better predict CVD occurrence.

Maternal omega-3 polyunsaturated fatty acids supplementation in pregnancy decreases MMP-1 levels in breastmilk: a cross-sectional study

INTRODUCTION

Anti-inflammatory properties of fish-oil are well known and suggested during pregnancy. MMP-1 is involved in inflammation and tissue remodelling. There have been studies focused on anti-inflammatory effect of maternal omega use on human milk while little is known about the effect of omega use on breastmilk proteases. Leptin is an important hormone that influences MMP levels in various tissues and exerts its metabolic effects. In our study we assessed the levels of MMP-1, TIMP-1, leptin, IL-6 and FA's including PUFA in breastmilk from women who used omega-3.

MATERIALS AND METHODS

Our study was a cross-sectional study included 67(Group 1, n = 32, omega user; Group 2 n = 35, non-user)lactating women and their infan MMP-1, TIMP-1, leptin, IL-6 and FA's were evaluated in breastmilk of both groups. MMP-1, TIMP-1, IL-6 and leptin were measured by enzyme-linked immunoabsorbent assay (ELISA) method. Breastmilk fatty acids were measured by gas chromatography flame ionisation detector (GC-FID).

RESULTS

Matrix metalloproteinase-1 (MMP-1) levels in breastmilk were significantly lower in breastmilk from omega users (mean ± SD, 0.455 ± 0.1) than non-users (mean ± SD, 0.677 ± 0.289) (p=.0001). MMP-1 and omega 6:3 ratio were positively correlated (r: 0.301, p=.01). MMP levels were correlated with IL-6 (Pearson's r: 0.411, p<.001). MMP-1 and leptin levels were positively correlated (r: .388, p=.001).

CONCLUSION

MMP-1 levels in breastmilk, may be modified by maternal omega use in pregnancy which may help to redirect extracellular matrix remodelling and metabolic programming in early infancy.

High-fat diet enhances starvation-induced hyperactivity via sensitizing hunger-sensing neurons in Drosophila

The function of the central nervous system to regulate food intake can be disrupted by sustained metabolic challenges such as high-fat diet (HFD), which may contribute to various metabolic disorders. Previously, we showed that a group of octopaminergic (OA) neurons mediated starvation-induced hyperactivity, an important aspect of food-seeking behavior (Yu et al., 2016). Here we find that HFD specifically enhances this behavior. Mechanistically, HFD increases the excitability of these OA neurons to a hunger hormone named adipokinetic hormone (AKH), via increasing the accumulation of AKH receptor (AKHR) in these neurons. Upon HFD, excess dietary lipids are transported by a lipoprotein LTP to enter these OA+AKHR+ neurons via the cognate receptor LpR1, which in turn suppresses autophagy-dependent degradation of AKHR. Taken together, we uncover a mechanism that links HFD, neuronal autophagy, and starvation-induced hyperactivity, providing insight in the reshaping of neural circuitry under metabolic challenges and the progression of metabolic diseases.

Vesicles Shed by Pathological Murine Adipocytes Spread Pathology: Characterization and Functional Role of Insulin Resistant/Hypertrophied Adiposomes

Extracellular vesicles (EVs) have recently emerged as a relevant way of cell to cell communication, and its analysis has become an indirect approach to assess the cell/tissue of origin status. However, the knowledge about their nature and role on metabolic diseases is still very scarce. We have established an insulin resistant (IR) and two lipid (palmitic/oleic) hypertrophied adipocyte cell models to isolate EVs to perform a protein cargo qualitative and quantitative Sequential Window Acquisition of All Theoretical Mass Spectra (SWATH) analysis by mass spectrometry. Our results show a high proportion of obesity and IR-related proteins in pathological EVs; thus, we propose a panel of potential obese adipose tissue EV-biomarkers. Among those, lipid hypertrophied vesicles are characterized by ceruloplasmin, mimecan, and perilipin 1 adipokines, and those from the IR by the striking presence of the adiposity and IR related transforming growth factor-beta-induced protein ig-h3 (TFGBI). Interestingly, functional assays show that IR and hypertrophied adipocytes induce differentiation/hypertrophy and IR in healthy adipocytes through secreted EVs. Finally, we demonstrate that lipid atrophied adipocytes shed EVs promote macrophage inflammation by stimulating IL-6 and TNFα expression. Thus, we conclude that pathological adipocytes release vesicles containing representative protein cargo of the cell of origin that are able to induce metabolic alterations on healthy cells probably exacerbating the disease once established.

Is "Leptin Resistance" Another Key Resistance to Manage Type 2 Diabetes?

Although novel pharmacological options for the treatment of type 2 diabetes mellitus (DM2) have been observed to modulate the functionality of several key organs in glucose homeostasis, successful regulation of insulin resistance (IR), body weight management, and pharmacological treatment of obesity remain notable problems in endocrinology. Leptin may be a pivotal player in this scenario, as an adipokine which centrally regulates appetite and energy balance. In obesity, excessive caloric intake promotes a low-grade inflammatory response, which leads to dysregulations in lipid storage and adipokine secretion. In turn, these entail alterations in leptin sensitivity, leptin transport across the blood-brain barrier and defects in post-receptor signaling. Furthermore, hypothalamic inflammation and endoplasmic reticulum stress may increase the expression of molecules which may disrupt leptin signaling. Abundant evidence has linked obesity and leptin resistance, which may precede or occur simultaneously to IR and DM2. Thus, leptin sensitivity may be a potential early therapeutic target that demands further preclinical and clinical research. Modulators of insulin sensitivity have been tested in animal models and small clinical trials with promising results, especially in combination with agents such as amylin and GLP-1 analogs, in particular, due to their central activity in the hypothalamus.

Risk Factors for Unhealthy Weight Gain and Obesity among Children with Autism Spectrum Disorder

Autism Spectrum Disorder (ASD) is a developmental disorder characterized by social and communication deficits and repetitive behaviors. Children with ASD are also at a higher risk for developing overweight or obesity than children with typical development (TD). Childhood obesity has been associated with adverse health outcomes, including insulin resistance, diabetes, heart disease, and certain cancers. Importantly some key factors that play a mediating role in these higher rates of obesity include lifestyle factors and biological influences, as well as secondary comorbidities and medications. This review summarizes current knowledge about behavioral and lifestyle factors that could contribute to unhealthy weight gain in children with ASD, as well as the current state of knowledge of emerging risk factors such as the possible influence of sleep problems, the gut microbiome, endocrine influences and maternal metabolic disorders. We also discuss some of the clinical implications of these risk factors and areas for future research.

A Low ω-6/ω-3 Ratio High-Fat Diet Improves Rat Metabolism via Purine and Tryptophan Metabolism in the Intestinal Tract, While Reversed by Inulin

A high-fat diet (HFD) is the main cause of metabolic diseases. However, HFD in previous studies consists of much lard, which contains a large amount of omega-6 (ω-6) polyunsaturated fatty acid (PUFA) and little omega-3 (ω-3) PUFA. The role of ω-6/ω-3 ratio of HFD in the development of metabolic diseases remains incompletely discussed. In this study, rats were fed with either a low or a high ω-6/ω-3 ratio HFD singly or combined with inulin. Metabolism state was valued and metabolomics of cecal content were detected. Results show that HFD with low ω-6/ω-3 ratio promotes the glucose utilization in rats. However, inulin had different effects on metabolism with different diets. Xanthosine and kynurenic acid in cecum were positively related to epididymal white adipose tissues (eWAT) mass. The present study indicates the beneficial effects of low ω-6/ω-3 ratio HFD (LRD) on the metabolic state of rats. Moreover, xanthosine and kynurenic acid were closely related to the development of metabolic diseases.

Leptin resensitisation: a reversion of leptin-resistant states

Leptin resistance refers to states in which leptin fails to promote its anticipated effects, frequently coexisting with hyperleptinaemia. Leptin resistance is closely associated with obesity and also observed in physiological situations such as pregnancy and in seasonal animals. Leptin resensitisation refers to the reversion of leptin-resistant states and is associated with improvement in endocrine and metabolic disturbances commonly observed in obesity and a sustained decrease of plasma leptin levels, possibly below a critical threshold level. In obesity, leptin resensitisation can be achieved with treatments that reduce body adiposity and leptinaemia, or with some pharmacological compounds, while physiological leptin resistance reverts spontaneously. The restoration of leptin sensitivity could be a useful strategy to treat obesity, maintain weight loss and/or reduce the recidivism rate for weight regain after dieting. This review provides an update and discussion about reversion of leptin-resistant states and modulation of the molecular mechanisms involved in each situation.

Leptin Receptor Signaling in Sim1-Expressing Neurons Regulates Body Temperature and Adaptive Thermogenesis

Leptin signals to regulate food intake and energy expenditure under conditions of normative energy homeostasis. The central expression and function of leptin receptor B (LepRb) have been extensively studied during the past two decades; however, the mechanisms by which LepRb signaling dysregulation contributes to the pathophysiology of obesity remains unclear. The paraventricular nucleus of the hypothalamus (PVN) plays a crucial role in regulating energy balance as well as the neuroendocrine axes. The role of LepRb expression in the PVN in regard to the regulation of physiological function of leptin has been controversial. The single-minded homolog 1 gene (Sim1) is densely expressed in the PVN and in parts of the amygdala, making Sim1-Cre mice a useful model for examining molecular mechanisms regulating PVN function. In this study, we characterized the physiological role of LepRb in Sim1-expressing neurons using LepRb-floxed × Sim1-Cre mice. Sim1-specific LepRb-deficient mice were surprisingly hypophagic on regular chow but gained more weight upon exposure to a high-fat diet than did their control littermates. We show that Sim1-specific deletion of a single LepRb gene copy caused decreased surface and core body temperatures as well as decreased energy expenditure in ambient room temperatures in both female and male mice. Furthermore, cold-induced adaptive (nonshivering) thermogenesis is disrupted in homozygous knockout mice. A defective thermoregulatory response was associated with defective cold-induced upregulation of uncoupling protein 1 in brown adipose tissue and reduced serum T4. Our study provides novel functional evidence supporting LepRb signaling in Sim1 neurons in the regulation of body weight, core body temperature, and cold-induced adaptive thermogenesis.