Matrix metalloproteinases are differentially expressed in adipose tissue during obesity and modulate adipocyte differentiation

Regional distribution of high-attenuation areas on chest computed tomography in the Multi-Ethnic Study of Atherosclerosis

High-attenuation areas (HAA) are a computed tomography-based quantitative measure of subclinical interstitial lung disease (ILD). We aimed to validate HAA in lung regions that are less subject to artefacts, such as extravascular lung water or dependent atelectasis. We examined the associations of HAA within six lung regions (basilar, non-basilar, peel, core, basilar peel, basilar core) with serum biomarkers of lung remodelling, forced vital capacity (FVC), visually-assessed interstitial lung abnormalities (ILA), and all-cause and ILD-specific mortality.

We performed cross-sectional and longitudinal analyses of participants in the Multi-Ethnic Study of Atherosclerosis, a prospective cohort of 6814 adults aged 45–84 years without known cardiovascular disease who underwent cardiac computed tomography.

Median regional HAA ranged from 3.8% in the peel to 4.8% in the basilar core. Doubling of regional HAA was associated with greater serum matrix metalloproteinase-7 (range 3.8% to 10.3%; p≤0.01), higher odds of ILA (OR 1.42 to 2.20; p≤0.03), and a higher risk of all-cause mortality (hazard ratio 1.20 to 1.47; p≤0.001). Doubling of regional HAA was associated with greater serum interleukin-6 (4.9% to 10.3%; p≤0.005) and higher risk of ILD-specific mortality (hazard ratio 3.30 to 3.98; p<0.001), except in the basilar core. Doubling of regional HAA was associated with lower FVC in the non-basilar, core and basilar core (113 mL to 186 mL; p<0.001).

Associations of HAA with lung remodelling biomarkers, ILA risk and all-cause mortality were consistent across all regions of the lung, including dependent areas where atelectasis may be present. These findings support the validity of HAA as a measure of pathologic subclinical ILD.

Evenwhen found in small regions of the lungs, high-attenuation areas, a CT-based quantitative measure of subclinical ILD, are associated with biomarkers of lung remodelling, risk of interstitial lung abnormalities and all-cause mortalityhttp://bit.ly/36psfin

Adipocytes in Breast Cancer, the Thick and the Thin

It is well established that breast cancer development and progression depend not only on tumor-cell intrinsic factors but also on its microenvironment and on the host characteristics. There is growing evidence that adipocytes play a role in breast cancer progression. This is supported by: (i) epidemiological studies reporting the association of obesity with a higher cancer risk and poor prognosis, (ii) recent studies demonstrating the existence of a cross-talk between breast cancer cells and adipocytes locally in the breast that leads to acquisition of an aggressive tumor phenotype, and (iii) evidence showing that cancer cachexia applies also to fat tissue and shares similarities with stromal-carcinoma metabolic synergy. This review summarizes the current knowledge on the epidemiological link between obesity and breast cancer and outlines the results of the tumor-adipocyte crosstalk. We also focus on systemic changes in body fat in patients with cachexia developed in the course of cancer. Moreover, we discuss and compare adipocyte alterations in the three pathological conditions and the mechanisms through which breast cancer progression is induced.

Relationships among oncostatin M, insulin resistance, and chronic inflammation: a pilot study

Objective Activated macrophages (M1-type macrophages) in adipose tissue secrete many proinflammatory cytokines that induce insulin resistance (IR). Oncostatin M (OSM), a member of the interleukin-6 (IL-6) family of Gp130 cytokines, plays an important role in a variety of biological functions, including the regulation of inflammatory responses. Proinflammatory cytokines released in patients with IR trigger a chronic, low-grade inflammatory reaction in blood vessel walls. This inflammator response leads to endothelial damage, which is the main mechanism for atherosclerosis and many cardiovascular diseases. Animal studies have reported a relationship between OSM and IR. To the best of our knowledge, however, few clinical studies have examined this topic. Therefore, we studied the relationship between serum levels of OSM and IR. Subjects and methods This prospective cross-sectional case-control study enrolled 50 people with IR (according to the HOMA-IR and QUICKI indices) and 34 healthy controls. The fasting blood concentrations of insulin, glucose, blood urea nitrogen (BUN), creatinine, aspartate aminotransferase (AST), alanine aminotransferase (ALT), low-density lipoprotein cholesterol (LDL-C), high-density lipoprotein cholesterol (HDL-C), triglyceride, total cholesterol, C-reactive protein (CRP), and OSM were determined. Results There were no significant differences between the two groups in age, sex, and HbA1c levels. Univariate analyses showed that waist circumference (WC) and levels of fasting glucose, insulin, CRP, HDL-C, OSM, HOMA-IR, and QUICKI differed between the two study groups. In multivariate analyses, both IR indices (QUICKI and HOMA) and OSM differed between the two groups. Conclusion OSM was correlated with the IR indices (QUICKI and HOMA). For simplicity, it might replace the other IR indices in the future. Further detailed studies are needed to confirm this.

Female adipose tissue has improved adaptability and metabolic health compared to males in aged obesity

Aging, like obesity, is associated with metabolic and inflammatory alterations within adipose tissue in older individuals. Younger females are protected from adipose inflammation, but older post-menopausal females exhibit exaggerated visceral adiposity correlated with increased disease risk. Obesity accelerates the onset and progression of age-associated diseases, but it is unclear if aging and obesity drive adipose tissue dysfunction in a sexually dimorphic fashion. We investigated adipose tissue metabolism and inflammation in a diet-induced obesity model in young and old mice. We identified age related sex differences in adipose tissue macrophages (ATMs), fibrosis and lipid metabolism in male and female visceral fat depot (GWAT). Although aging normalized body weights between the sexes, females remained protected from proinflammatory ATMs and stimulated lipolysis failed to adversely affect the inflammatory state even with obesity. Older obese males had augmented CD11c⁺ ATMs and higher insulin levels, while females showed increased visceral adiposity and exaggerated Pparγ, and Pgc1α expression. Obesity in aging demonstrated similar expression of GWAT p53, p16, p21, Timp1 and Tgfβ1 in both sexes. Our studies suggest that even with aging, female GWAT shows an attenuated inflammatory response compared to males due to an efficient oxidative metabolism combined with an active tissue remodeling state.

Adipocytes in the Tumour Microenvironment

Adipose tissue contribution to body mass ranges from 6% in male athletes to over 25% in obese men and over 30% in obese women. Crosstalk between adipocytes and cancer cells that exist in close proximity can lead to changes in the function and phenotype of both cell types. These interactions actively alter the tumour microenvironment (TME). Obesity is one of the major risk factors for multiple types of cancer, including breast cancer. In obesity, the increase in both size and number of adipocytes leads to instability of the TME, as well as increased hypoxia within the TME, which further enhances tumour invasion and metastasis. In this chapter, we will discuss the diverse aspects of adipocytes and adipocyte-derived factors that affect the TME as well as tumour progression and metastasis. In addition, we discuss how obesity affects the TME. We focus primarily on breast cancer but discuss what is known in other cancer types when relevant. We finish by discussing the studies needed to further understand these complex interactions.

Multifaceted Oncogenic Role of Adipocytes in the Tumour Microenvironment

Obesity has for decades been recognised as one of the major health concerns. Recently accumulated evidence has established that obesity or being overweight is strongly linked to an increased risk of cancer. However, it is still not completely clear how adipose tissue (fat), along with other stromal connective tissues and cells, contribute to tumour initiation and progression. In the tumour microenvironment, the adipose tissue cells, in particular the adipocytes, secrete a number of adipokines, including growth factors, hormones, collagens, fatty acids, and other metabolites as well as extracellular vesicles to shape and condition the tumour and its microenvironment. In fact, the adipocytes, through releasing these factors and materials, can directly and indirectly facilitate cancer cell proliferation, apoptosis, metabolism, angiogenesis, metastasis and even chemotherapy resistance. In this chapter, the multidimensional role played by adipocytes, a major and functional component of the adipose tissue, in promoting cancer development and progression within the tumour microenvironment will be discussed.

Brucella abortus Infection Modulates 3T3-L1 Adipocyte Inflammatory Response and Inhibits Adipogenesis

Brucellosis is a prevalent global zoonotic infection but has far more impact in developing countries. The adipocytes are the most abundant cell type of adipose tissue and their secreted factors play an important role in several aspects of the innate and adaptive immune response. Here, we demonstrated the ability of Brucella abortus to infect and replicate in both adipocytes and its precursor cells (pre-adipocytes) derived from 3T3-L1 cell line. Additionally, infection of pre-adipocytes also inhibited adipogenesis in a mechanism independent of bacterial viability and dependent on lipidated outer membrane protein (L-Omp19). B. abortus infection was able to modulate the secretion of IL-6 and the matrix metalloproteases (MMPs) -2 and-9 in pre-adipocytes and adipocytes, and also modulated de transcription of adiponectin, leptin, and resistin in differentiated adipocytes. B. abortus-infected macrophages also modulate adipocyte differentiation involving a TNF-α dependent mechanism, thus suggesting a plausible interplay between B. abortus, adipocytes, and macrophages. In conclusion, B. abortus is able to alter adipogenesis process in adipocytes and its precursors directly after their infection, or merely their exposure to the B. abortus lipoproteins, and indirectly through soluble factors released by B. abortus-infected macrophages.

Tissue Inhibitor of Metalloproteinase 3 Deficiency Disrupts the Hepatocyte E-Cadherin/β-Catenin Complex and Induces Cell Death in Liver Ischemia/Reperfusion Injury

Tissue inhibitor of metalloproteinase (TIMP) 3 is a naturally occurring inhibitor of a broad range of proteases, with key roles in extracellular matrix turnover and in the pathogenesis of various diseases. In this study, we investigated the response of mice lacking TIMP3 (TIMP3-/-) to hepatic ischemia/reperfusion injury (IRI). We report here that TIMP3-/- mice showed an enhanced inflammatory response, exacerbated organ damage, and further impaired liver function after IRI when compared with their wild-type littermates. Loss of TIMP3 led to the cleavage and shedding of E-cadherin during hepatic IRI; the full-length 120-kDa E-cadherin and the ratio of 38-kDa C-terminal fragment/120-kDa E-cadherin were decreased and increased, respectively, in TIMP3-/- livers after IRI. Moreover, GI254023X, a potent inhibitor of a disintegrin and metalloprotease (ADAM) 10, was capable of partially rescuing the expression of E-cadherin in the TIMP3-null hepatocytes. The proteolysis of E-cadherin in the TIMP3-/- livers was also linked to the loss of β-catenin from the hepatocyte membranes and to an increased susceptibility to apoptosis after liver IRI. In a similar fashion, depression of the E-cadherin/β-catenin complex mediated by TIMP3 deletion and knockdown of β-catenin by small interfering RNA were both capable of inducing caspase activation in isolated hepatocytes subjected to H₂ O₂ oxidative stress. Hence, these results support a protective role for TIMP3 expression in sheltering the hepatocyte E-cadherin/β-catenin complex from proteolytic processing and inhibiting apoptosis after hepatic IRI.

Timp3 deficiency affects the progression of DEN-related hepatocellular carcinoma during diet-induced obesity in mice

AIM

Obesity and low-grade inflammation are associated with an increased risk of hepatocellular carcinoma (HCC), a leading cause of cancer-related death worldwide. The tissue inhibitor of metalloproteinase (TIMP) 3, an endogenous inhibitor of protease activity that represents a key mediator of inflammation, is reduced in inflammatory metabolic disorders and cancer. In contrast, Timp3-deficient mice (Timp3^-/-) are highly resistant to developing HCC in response to a diethylnitrosamine (DEN); therefore, we aimed to elucidate the biological role of genetic loss of Timp3 in obesity-related hepatocarcinogenesis.

METHODS

Fourteen-day-old male wild-type (wt) and Timp3^-/- mice were injected with 25 mg/kg DEN or an equal volume of saline. After 4 weeks, mice were randomized into two dietary groups and fed either normal or high-fat diet and allowed to grow until 32 weeks of age. Liver histological features were analyzed, and differentially expressed genes in the liver were quantified.

RESULTS

In Timp3^-/- mice fed with the obesogenic diet, despite the increase in liver steatosis and inflammation, both the number of tumors and the total tumor size are significantly reduced 30 weeks post-DEN injection, compared to control mice. Moreover, Timp3 deletion in hepatocarcinogenesis during obesity is associated with a reduction in FoxM1 transcriptional activity through H19/miR-675/p53 pathway.

CONCLUSIONS

This study suggests that Timp3 ablation leads to cell cycle perturbation, at least in part by repressing FoxM1 transcriptional activity through H19/miR-675/p53 pathway.

Fibroblast feeder layer supports adipogenic differentiation of human adipose stromal/progenitor cells

Adipose stromal/progenitor cells (ASCs) can differentiate into adipocytes in the course of adipogenesis. This process is governed by systemic factors and signals of the adipose stem cell niche. ASCs isolated from fat tissues and amplified in vitro provide an essential and reliable model system to study adipogenesis. However, current cell culture models routinely grow ASCs on plastic surfaces largely missing niche parameters. In the present communication, we employed human foreskin fibroblasts (HFFs) monolayers as feeder cells for ASCs, which were isolated from human subcutaneous white adipose tissue and amplified in vitro. We found that PPARγ2 and several adipocyte markers were significantly higher expressed in differentiated ASCs growing on feeder layers relative to plastic dishes. Moreover, a significant higher number of adipocytes was generated from ASCs cultured on feeder layer and these adipocytes contained larger fat droplets. Insulin strongly stimulated glucose uptake into adipocytes produced on feeder layer suggesting that these cells show characteristic metabolic features of fat cells.  Finally, we show that the HFF feeder layer allows adipogenic differentiation of low-density-seeded ASCs. In conclusion, we demonstrate that the HFF feeder layer increases adipocyte differentiation of ASCs and allows differentiation of low density seeded progenitor cells  into functional adipocytes.

Effect of a Very-Low-Calorie Ketogenic Diet on Circulating Myokine Levels Compared with the Effect of Bariatric Surgery or a Low-Calorie Diet in Patients with Obesity

: The preservation of muscle mass and muscle function after weight loss therapy is currently a considerable challenge in the fight against obesity. Muscle mass secretes proteins called myokines that have relevant functions in the regulation of metabolism and health. This study was aimed to evaluate whether a very low-calorie ketogenic (VLCK) diet may modulate myokine levels, in addition to changes in body composition, compared to a standard, balanced low-calorie (LC) diet or bariatric surgery in patients with obesity. Body composition, ketosis, insulin sensitivity and myokines were evaluated in 79 patients with overweight/obesity after a therapy to lose weight with a VLCK diet, a LC diet or bariatric surgery. The follow-up was 6 months. The weight loss therapies induced changes in myokine levels in association with changes in body composition and biochemical parameters. The effects on circulating myokine levels compared to those at baseline were stronger after the VLCK diet than LC diet or bariatric surgery. Differences reached statistical significance for IL-8, MMP2 and irisin. In conclusion, nutritional interventions or bariatric surgery to lose weight induces changes in circulating myokine levels, being this effect potentially most notable after following a VLCK diet.

High-Protein Diet Associated with Bocaiuva Supplementation Decreases Body Fat and Improves Glucose Tolerance in Resistance-Trained Rats

High-protein diets (HPDs) are widely used for health and performance. However, the combination of whey protein and natural foods (i.e., fruits) is still unclear. Thus, we evaluated the role of supplemental HPD with Bocaiuva (Acrocomia sp.) in metabolic and body composition parameters of rats submitted to resistance training (RT). Wistar rats (203.3 ± 30 g) were randomly allocated to five groups: normoproteic control (CON, n = 5), sedentary high-protein (SH, n = 5), RT + H (trained high-protein [TH], n = 5), sedentary+Bocaiuva (SH+B, n = 4), and RT+Bocaiuva (TH+B, n = 4) diet groups. After 12 weeks of RT, the maximal strength increased in both trained groups (P < .05). The TH + B group had lower values of adiposity index (AI) (3.8 ± 0.7% vs. 6.8 ± 1.3%) and visceral fat (0.038 ± 0.004 g/g vs. 0.067 ± 0.012 g/g) compared with the SH group, respectively (P < .05). The other groups did not show differences in values of AI (CON, 5.4 ± 1.6%, TH, 5.4 ± 1.3%, and SH+B, 5.5 ± 1.2%). In addition, the fasting glucose of trained groups (TH, 106.0 ± 4.5, and TH+B, 100.4 ± 13.5 dL/mg) was significantly lower when compared with controls (SH, 120.0 ± 14.4, and SH+B, 119 ± 6.4 dL/mg) (P < .05). Bocaiuva combined with an HPD reduced visceral fat and AI in addition to improving glucose tolerance of rats submitted to RT.

Factors which Influence the Levels of ST-2, Galectin-3 and MMP-9 in Acute Coronary Syndrome

BACKGROUND

Several cardiac biomarkers are being studied to explore their potential in the prognostication of Acute Coronary Syndrome (ACS). However, there are limited studies exploring the relationship between these biomarkers and clinical, laboratory and demographic characteristics.

OBJECTIVE

We sought to determine the factors which influence the concentration of novel cardiac biomarkers such as Galectin-3, suppression of tumorigenicity-2 (ST-2) and Matrix Metallopeptidase-9 (MMP-9) in patients with ACS.

METHODS

A total of 122 patients with ACS were enrolled in the study. The study patients were categorized into two groups namely: STEMI (n=58) and NSTEMI/UA (n=64). Plasma samples were used to determine the level of biomarkers, Galectin-3 and ST-2, and serum samples were used to determine the levels of MMP-9 using the Enzyme-linked immunosorbent assay (ELISA). The association between the plasma and serum levels of biomarkers and, demographic, clinical and laboratory variables were determined. Statistical analyses for the study were performed using SPSS 16.0 software (SPSS Inc., Chicago, IL, USA).

RESULTS

Elderly aged [0.107 (0.012-0.969); p=0.047] patients had higher ST-2. Galectin-3 was higher among female patients [3.693(1.253-10.887); p=0.018] and patients with low left ventricular ejection fraction [2.882 (1.041-7.978); p=0.042]. Patients with lower body mass index [3.385 (1.241-9.231); p=0.017], diabetes [3.650 (1.302-10.237); p=0.014] and high total leukocyte count [2.900 (1.114-7.551; p=0.029] had higher MMP-9 levels.

CONCLUSION

The concentration of galectin-3, ST-2 and MMP-9 are independently influenced by demographic, clinical and laboratory characteristics. It is estimated that these factors should be accounted for when interpreting the results of the biomarker assays.

Fibroadipogenic progenitors are responsible for muscle loss in limb girdle muscular dystrophy 2B

Muscle loss due to fibrotic or adipogenic replacement of myofibers is common in muscle diseases and muscle-resident fibro/adipogenic precursors (FAPs) are implicated in this process. While FAP-mediated muscle fibrosis is widely studied in muscle diseases, the role of FAPs in adipogenic muscle loss is not well understood. Adipogenic muscle loss is a feature of limb girdle muscular dystrophy 2B (LGMD2B) - a disease caused by mutations in dysferlin. Here we show that FAPs cause the adipogenic loss of dysferlin deficient muscle. Progressive accumulation of Annexin A2 (AnxA2) in the myofiber matrix causes FAP differentiation into adipocytes. Lack of AnxA2 prevents FAP adipogenesis, protecting against adipogenic loss of dysferlinopathic muscle while exogenous AnxA2 enhances muscle loss. Pharmacological inhibition of FAP adipogenesis arrests adipogenic replacement and degeneration of dysferlin-deficient muscle. These results demonstrate the pathogenic role of FAPs in LGMD2B and establish these cells as therapeutic targets to ameliorate muscle loss in patients.

Intraoperative immunomodulatory effects of sevoflurane versus total intravenous anesthesia with propofol in bariatric surgery (the OBESITA trial): study protocol for a randomized controlled pilot trial

Background

Obesity is associated with a chronic systemic inflammatory process. Volatile or intravenous anesthetic agents may modulate immune function, and may do so differentially in obesity. However, no study has evaluated whether these potential immunomodulatory effects differ according to type of anesthesia in obese patients undergoing laparoscopic bariatric surgery.

Methods/design

The OBESITA trial is a prospective, nonblinded, single-center, randomized, controlled clinical pilot trial. The trial will include 48 patients with a body mass index ≥ 35 kg/m², scheduled for laparoscopic bariatric surgery using sleeve or a Roux-en-Y gastric bypass technique, who will be allocated 1:1 to undergo general inhalational anesthesia with sevoflurane or total intravenous anesthesia (TIVA) with propofol. The primary endpoint is the difference in plasma interleukin (IL)-6 levels when comparing the two anesthetic agents. Blood samples will be collected prior to anesthesia induction (baseline), immediately after anesthetic induction, and before endotracheal extubation. Levels of other proinflammatory and anti-inflammatory cytokines, neutrophil chemotaxis, macrophage differentiation, phagocytosis, and occurrence of intraoperative and postoperative complications will also be evaluated.

Discussion

To our knowledge, this is the first randomized clinical trial designed to compare the effects of two different anesthetics on immunomodulation in obese patients undergoing laparoscopic bariatric surgery. Our hypothesis is that anesthesia with sevoflurane will result in a weaker proinflammatory response compared to anesthesia with propofol, with lower circulating levels of IL-6 and other proinflammatory mediators, and increased macrophage differentiation into the M2 phenotype in adipose tissue.

Trial registration

Registro Brasileiro de Ensaios Clínicos, RBR-77kfj5. Registered on 25 July 2018.

Electronic supplementary material

The online version of this article (10.1186/s13063-019-3399-z) contains supplementary material, which is available to authorized users.

Antibody-mediated targeting of cleavage-specific OPN-T cell interactions

T cells are crucial players in obesity-mediated adipose tissue inflammation. We hypothesized that osteopontin (OPN), an inflammatory protein with enhanced activity when proteolytically cleaved, affects the number of viable T cells in adipose tissue and assessed inhibition of the interaction between T cells and thrombin and matrix metalloproteinases-cleaved OPN using antibodies and postimmune sera. Gene expression of T cell markers in adipose tissue from wild-type (wt) and Spp1-/- (OPN deficient) mice was analyzed after 16 weeks of high fat diet (HFD) or low fat diet (LFD) feeding. CD3, CD8 and OPN gene expression in omental adipose tissue from individuals with obesity was measured. OPN-T cell interactions were assessed with a fluorescence-based adhesion assay and blocked with antibodies targeting OPN. Comparison of T cell gene expression in adipose tissue from wt and Spp1-/- mice showed that OPN affected the number of T cells while in humans, levels of OPN correlated with T cell markers in omental adipose tissue. The interaction between T cells and cleaved OPN was blocked by postimmune sera following OPN peptide vaccinations and with monoclonal antibodies. In conclusion, levels of OPN affected the number of T cells in obesity and antibodies against cleaved OPN antagonize OPN-T cell interactions.

Peanut Sprout Extracts Attenuate Triglyceride Accumulation by Promoting Mitochondrial Fatty Acid Oxidation in Adipocytes

Peanut sprouts (PS), which are germinated peanut seeds, have recently been reported to have anti-oxidant, anti-inflammatory, and anti-obesity effects. However, the underlying mechanisms by which PS modulates lipid metabolism are largely unknown. To address this question, serial doses of PS extract (PSE) were added to 3T3-L1 cells during adipocyte differentiation. PSE (25 µg/mL) significantly attenuated adipogenesis by inhibiting lipid accumulation in addition to reducing the level of adipogenic protein and gene expression with the activation of AMP-activated protein kinase (AMPK). Other adipocyte cell models such as mouse embryonic fibroblasts C3H10T1/2 and primary adipocytes also confirmed the anti-adipogenic properties of PSE. Next, we investigated whether PSE attenuated lipid accumulation in mature adipocytes. We found that PSE significantly suppressed lipogenic gene expression, while fatty acid (FA) oxidation genes were upregulated. Augmentation of FA oxidation by PSE in mature 3T3-L1 adipocytes was confirmed via a radiolabeled-FA oxidation rate experiment by measuring the conversion of [³H]-oleic acid (OA) to [³H]-H₂O. Furthermore, PSE enhanced the mitochondrial oxygen consumption rate (OCR), especially maximal respiration, and beige adipocyte formation in adipocytes. In summary, PSE was effective in reducing lipid accumulation in 3T3-L1 adipocytes through mitochondrial fatty acid oxidation involved in AMPK and mitochondrial activation.

Elucidating the Preadipocyte and Its Role in Adipocyte Formation: a Comprehensive Review

Adipogenesis is a complex process whereby the multipotent adipose-derived stem cell is converted to a preadipocyte before terminal differentiation into the mature adipocyte. Preadipocytes are present throughout adult life, exhibit adipose fat depot specificity, and differentiate and proliferate from distinct progenitor cells. The mechanisms that promote preadipocyte commitment and maturation involve numerous protein factor regulators, epigenetic factors, and miRNAs. Detailed characterization of this process is currently an area of intense research and understanding the roles of preadipocytes in tissue plasticity may provide insight into novel approaches for tissue engineering, regenerative medicine and treating a host of obesity-related conditions. In the current study, we analyzed the current literature and present a review of the characteristics of transitioning adipocytes and detail how local microenvironments influence their progression towards terminal differentiation and maturation. Specifically, we detail the characterization of preadipocyte via surface markers, examine the signaling cascades and regulation behind adipogenesis and cell maturation, and survey their role in tissue plasticity and health and disease.

Identification of Potential Key Genes Associated with Adipogenesis through Integrated Analysis of Five Mouse Transcriptome Datasets

Adipose tissue is the most important energy metabolism and secretion organ, and these functions are conferred during the adipogenesis process. However, the cause and the molecular events underlying adipogenesis are still unclear. In this study, we performed integrated bioinformatics analyses to identify vital genes involved in adipogenesis and reveal potential molecular mechanisms. Five mouse high-throughput expression profile datasets were downloaded from the Gene Expression Omnibus (GEO) database; these datasets contained 24 samples of 3T3-L1 cells during adipogenesis, including 12 undifferentiated samples and 12 differentiated samples. The five datasets were reanalyzed and integrated to select differentially expressed genes (DEGs) during adipogenesis via the robust rank aggregation (RRA) method. Functional annotation of these DEGs and mining of key genes were then performed. We also verified the expression levels of some potential key genes during adipogenesis. A total of 386 consistent DEGs were identified, with 230 upregulated genes and 156 downregulated genes. Gene Ontology (GO) analysis showed that the biological functions of the DEGs primarily included fat cell differentiation, lipid metabolic processes, and cell adhesion. Kyoto Encyclopedia of Genes and Genomes (KEGG) analysis showed that these DEGs were mainly associated with metabolic pathways, the peroxisome proliferator-activated receptor (PPAR) signaling pathway, regulation of lipolysis in adipocytes, the tumor necrosis factor (TNF) signaling pathway, and the FoxO signaling pathway. The 30 most closely related genes among the DEGs were identified from the protein⁻protein interaction (PPI) network and verified by real-time quantification during 3T3-L1 preadipocyte differentiation. In conclusion, we obtained a list of consistent DEGs during adipogenesis through integrated analysis, which may offer potential targets for the regulation of adipogenesis and treatment of adipose dysfunction.

Fat fibrosis: friend or foe?

At the simplest level, obesity is the manifestation of an imbalance between caloric intake and expenditure; however, the pathophysiological mechanisms that govern the development of obesity and associated complications are enormously complex. Fibrosis within the adipose tissue compartment is one such factor that may influence the development of obesity and/or obesity-related comorbidities. Furthermore, the functional consequences of adipose tissue fibrosis are a matter of considerable debate, with evidence that fibrosis serves both adaptive and maladaptive roles. Tissue fibrosis itself is incompletely understood, and multiple cellular and molecular pathways are involved in the development, maintenance, and resolution of the fibrotic state. Within the context of obesity, fibrosis influences molecular and cellular events that relate to adipocytes, inflammatory cells, inflammatory mediators, and supporting adipose stromal tissue. In this Review, we explore what is known about the interplay between the development of adipose tissue fibrosis and obesity, with a view toward future investigative and therapeutic avenues.

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

Obesity and related morbidities pose a major health threat. Obesity is associated with increased blood concentrations of the anorexigenic hormone leptin; however, obese individuals are resistant to its anorexigenic effects. We examined the phenomenon of reduced leptin signaling in a high-fat diet-induced obesity model in mice. Obesity promoted matrix metalloproteinase-2 (Mmp-2) activation in the hypothalamus, which cleaved the leptin receptor's extracellular domain and impaired leptin-mediated signaling. Deletion of Mmp-2 restored leptin receptor expression and reduced circulating leptin concentrations in obese mice. Lentiviral delivery of short hairpin RNA to silence Mmp-2 in the hypothalamus of wild-type mice prevented leptin receptor cleavage and reduced fat accumulation. In contrast, lentiviral delivery of Mmp-2 in the hypothalamus of Mmp-2-/- mice promoted leptin receptor cleavage and higher body weight. In a genetic mouse model of obesity, transduction of cleavage-resistant leptin receptor in the hypothalamus reduced the rate of weight gain compared to uninfected mice or mice infected with the wild-type receptor. Immunofluorescence analysis showed that astrocytes and agouti-related peptide neurons were responsible for Mmp-2 secretion in mice fed a high-fat diet. These results suggest a mechanism for leptin resistance through activation of Mmp-2 and subsequent cleavage of the extracellular domain of the leptin receptor.

FSP1-positive fibroblasts are adipogenic niche and regulate adipose homeostasis

Adipocyte progenitors reside in the stromal vascular fraction (SVF) of adipose tissues that are composed of fibroblasts, immune cells, and endothelial cells. It remains to be elucidated how the SVF regulates adipocyte progenitor fate determination and adipose homeostasis. Here, we report that fibroblast-specific protein-1 (FSP1)⁺ fibroblasts in the SVF are essential to adipose homeostasis. FSP1⁺ fibroblasts, devoid of adipogenic potential, are adjacent to the preadipocytes in the SVF. Ablation of FSP1⁺ fibroblasts in mice severely diminishes fat content of adipose depots. Activation of canonical Wnt signaling in the FSP1⁺ fibroblasts results in gradual loss of adipose tissues and resistance to diet-induced obesity. Alterations in the FSP1⁺ fibroblasts reduce platelet-derived growth factor (PDGF)-BB signaling and result in the loss of preadipocytes. Reduced PDGF-BB signaling, meanwhile, impairs the adipogenic differentiation capability of preadipocytes by regulating matrix metalloproteinase (MMP) expression, extracellular matrix remodeling, and the activation of Yes-associated protein (YAP) signaling. Thus, FSP1⁺ fibroblasts are an important niche essential to the maintenance of the preadipocyte pool and its adipogenic potential in adipose homeostasis.

White adipose tissue (WAT), which consists mostly of adipocytes, is not only a passive energy storage but also an active metabolic and endocrine organ in the body. The importance of maintaining proper adipose mass is emphasized by the fact that both adipose tissue excess—in obese individuals—and deficiency have adverse metabolic consequences. In order to maintain the number of adipocytes, there is a continuous turnover from preadipocytes in adults. Like any other adult stem cells and progenitor cells, cell fate and differentiation capability of preadipocytes are tightly regulated by a highly specialized niche. However, what constitutes the preadipocyte niche, and how the niche regulates preadipocyte function and adipose homeostasis, remain poorly known. In this study, we have identified fibroblast-specific protein-1 (FSP1)⁺ fibroblasts in the WAT stromal vascular fraction (SVF) of mice as the niche for preadipocytes. We show that FSP1⁺ fibroblasts with aberrant Wnt signaling fail to maintain the preadipocyte pool and its differentiation potential, resulting in loss of adipose tissue. We conclude that FSP1⁺ fibroblasts are a niche for preadipocytes and regulate adipose tissue homeostasis in adult mice.

Elevated Pentraxin 3 in Obese Adipose Tissue Promotes Adipogenic Differentiation by Activating Neuropeptide Y Signaling

Obesity is accompanied by chronic systemic inflammation characterized by macrophage infiltration of obese tissues, an elevated plasma level of inflammatory substances, and excessive accumulation of lipids. The pro-inflammatory factor pentraxin 3 (PTX3) is also elevated in obese tissues, suggesting its potential role in adipogenesis. We found by analyzing murine preadipocyte 3T3-L1 cells, and human adipocytes derived from mesenchymal stem cells, which locally elevated PTX3 in obese adipose tissue augments adipocyte differentiation and subsequent lipid accumulation. This occurs via the upregulation of adipogenesis-related transcription factors. PTX3 enhanced lipid accumulation in murine 3T3-L1 cells by upregulating the expression of neuropeptide Y (NPY)/NPY receptor (NPYR) expression in preadipocytes. Pharmacological inhibition by NPYR antagonists abolished these effects. NPY also promoted the production of reactive oxygen species (ROS), a known trigger of adipogenesis. NPYR antagonists as well as antioxidant N-acetylcysteine showed anti-adipogenic effects by reducing the ROS levels, indicating that PTX3 mediates adipogenesis through NPY-dependent ROS production. These findings suggest that PTX3 plays a key role in the development of obesity by enhancing adipocyte differentiation and lipid synthesis via NPY/NPYR signaling. These observations provide a mechanistic explanation for the adipogenesis mediated by PTX3.

Adipose tissue derived-factors impaired pancreatic β-cell function in diabetes

Inflammatory factors produced and secreted by adipose tissue, in particular peri-pancreatic adipose tissue (P-WAT), may influence pancreatic β-cell dysfunction. Using the ZDF Rat model of diabetes, we show the presence of infiltrating macrophage (ED1 staining) on pancreatic tissue and P-WAT in the pre-diabetes stage of the disease. Then, when the T2D is installed, infiltrating cells decreased. Meanwhile, the P-WAT conditioned-medium composition, in terms of inflammatory factors, varies during the onset of the T2D. Using chemiarray technology, we observed an over expression of CXCL-1, -2, -3, CCL-3/MIP-1α and CXCL-5/LIX and TIMP-1 in the 9 weeks old obese ZDF pre-diabetic rat model. Surprisingly, the expression profile of these factors decreased when animals become diabetic (12 weeks obese ZDF rats). The expression of these inflammatory proteins is highly associated with inflammatory infiltrate. P-WAT conditioned-medium from pre-diabetes rats stimulates insulin secretion, cellular proliferation and apoptosis of INS-1 cells. However, inhibition of conditioned-medium chemokines acting via CXCR2 receptor do not change cellular proliferation apoptosis and insulin secretion of INS-1 cells induced by P-WAT conditioned-medium. Taken together, these results show that among the secreted chemokines, increased expression of CXCL-1, -2, -3 and CXCL-5/LIX in P-WAT conditioned-medium is concomitant with the onset of the T2D but do not exerted a direct effect on pancreatic β-cell dysfunction.

Adipocyte Death and Chronic Inflammation in Obesity

Cell death is closely linked to many diseases including cancer, neurodegenerative diseases, autoimmune diseases, and metabolic disorders. Increased adipocyte death has been reported during the development of obesity. Adipocyte death may be caused by excessive stress during obesity-related adipose tissue remodeling. Adipose tissue macrophages are key players in obesity-related inflammation and systemic insulin resistance. Accumulating evidence suggests that adipocyte death is involved in immune cell function and initiates inflammation through an interaction with macrophages; however, the precise mechanisms remain largely unknown. This review focuses on the contribution of dead cells (particularly dead adipocytes in adipose tissue) to the pathophysiological conditions associated with obesity. J. Med. Invest. 64: 193-196, August, 2017.

Antiangiogenic Herbal Composition Ob-X Reduces Abdominal Visceral Fat in Humans: A Randomized, Double-Blind, Placebo-Controlled Study

Adipose tissue growth is angiogenesis-dependent, and angiogenesis inhibitors can regulate adipose tissue mass by cutting off the blood supply. We examined whether antiangiogenic herbal composition Ob-X can reduce fast-growing abdominal fat, especially visceral fat in humans by inhibiting angiogenesis. Eighty abdominally obese subjects (body mass index: 25-29.9 kg/m², waist circumference: exceeding 90 cm for males and 85 cm for females) participated in a 12-week randomized, double-blind, placebo-controlled human study to evaluate the efficacy and safety of Ob-X. 690 mg of Ob-X was administered orally twice a day. The Ob-X group showed a noticeable reduction in visceral fat of 20.5% after the 12-week treatment as compared to baseline measured by computed tomography. The change in visceral fat in the Ob-X group was statistically significant as compared to the placebo group (p = 0.0495) and 1.9 times higher than in the placebo group. Therefore, angiogenesis inhibitor Ob-X has the potential to improve obesity-related metabolic syndrome by reducing dangerous visceral fat.

Transcription factor 21 (TCF21) promotes proinflammatory interleukin 6 expression and extracellular matrix remodeling in visceral adipose stem cells

The visceral (VIS) and subcutaneous (SQ) fat pads are developmentally distinct white adipose tissue depots and contribute differently to inflammation and insulin resistance associated with obesity. The basic helix-loop-helix transcriptional regulator, transcription factor 21 (TCF21), is a marker gene for white adipose tissues and is abundantly expressed in VIS-derived adipose stem cells (ASCs), but not in SQ-derived ASCs. However, TCF21's role in regulating fat depot-specific gene expression and function is incompletely understood. Here, using siRNA-mediated Tcf21 knockdowns and lentiviral gene transfer of TCF21 in mouse ASCs, we demonstrate that TCF21 is required for the VIS ASC-specific expression of interleukin 6 (IL6), a key cytokine that contributes to the proinflammatory nature of VIS depots. Concurrently, TCF21 promotes MMP-dependent collagen degradation and type IV collagen deposition through the regulation of the extracellular matrix (ECM) modifiers, matrix metalloproteinase (MMP) 2, MMP13, and tissue inhibitor of MMP1 (TIMP1), as well as collagen type IV α1 chain (COL4A1) in VIS ASCs. We also found that although IL6 mediates the expression of Mmp13 and Timp1 in VIS ASCs, the TCF21-dependent expression of Mmp2 and Col4a1 is IL6-independent. These results suggest that TCF21 contributes to the proinflammatory environment in VIS fat depots and to active ECM remodeling of these depots by regulating IL6 expression and MMP-dependent ECM remodeling in a spatiotemporally coordinated manner.

Extracellular matrix dynamics during mesenchymal stem cells differentiation

Mesenchymal stem cells (MSCs) are stromal cells that display self-renewal and multipotent differentiation capacity. The repertoire of mature cells generated ranges but is not restricted to: fat, bone and cartilage. Their potential importance for both cell therapy and maintenance of in vivo homeostasis is indisputable. Nonetheless, both their in vivo identity and use in cell therapy remain elusive. A drawback generated by this fact is that little is known about the MSC niche and how it impacts differentiation and homeostasis maintenance. Hence, the roles played by the extracellular matrix (ECM) and its main regulators namely: the Matrix Metalloproteinases (MMPs) and their counteracting inhibitors (TIMPs and RECK) upon stem cells differentiation are only now beginning to be unveiled. Here, we will focus on mesenchymal stem cells and review the main mechanisms involved in adipo, chondro and osteogenesis, discussing how the extracellular matrix can impact not only lineage commitment, but, also, their survival and potentiality. This review critically analyzes recent work in the field in an effort towards a better understanding of the roles of Matrix Metalloproteinases and their inhibitors in the above-cited events.

Spheroid Culture System Confers Differentiated Transcriptome Profile and Functional Advantage to 3T3-L1 Adipocytes

This study highlights functional differences between 2-D monolayer and 3-D spheroid 3T3-L1 adipocyte culture models and explores the underlying genomic mechanisms responsible for the different phenotypes present. The spheroids showed higher triglyceride accumulation than the monolayer culture and further increase with larger spheroid size. Whole transcriptome analysis indicated significant differential expression of genes related to adipogenesis, including adipocytokine signaling, fatty acid metabolism, and PPAR-γ signaling. Spheroids also showed downregulation of matrix metalloproteinases (MMPs), integrin, actin-cytoskeleton associated genes, and Rho/GTPase3 expression relative to 2-D monolayer, indicating suppression of the Rho-ROCK pathway and thereby promoting adipogenic differentiation. When exposed to linoleic acid (500 μM) and TNF-α (125 ng/mL) to promote chronic adiposity, linoleic acid treatment resulted in increased intracellular triglycerides and subsequent TNF-α treatment resulted in significantly altered adipocytokine signaling, fatty acid metabolism, and PPAR signaling, in addition to upregulation of multiple MMPs in spheroids vs. monolayer. Overall, 3-D spheroids showed enhanced adipogenic phenotype as indicated by triglyceride synthesis and transcriptome changes while retaining sensitivity to a pro-inflammatory stimulus. The 3-D spheroid culture thus may provide a simple, convenient, and sensitive in vitro model to study adipocyte response to metabolic stresses relevant to clinical pathologies.

Emerging nonmetabolic functions of skin fat

Although the major white adipose depots evolved primarily to store energy, secrete hormones and thermo-insulate the body, multiple secondary depots developed additional specialized and unconventional functions. Unlike any other fat tissue, dermal white adipose tissue (dWAT) evolved a large repertoire of novel features that are central to skin physiology, which we discuss in this Review. dWAT exists in close proximity to hair follicles, the principal appendages of the skin that periodically grow new hairs. Responding to multiple hair-derived signals, dWAT becomes closely connected to cycling hair follicles and periodically cycles itself. At the onset of new hair growth, hair follicles secrete activators of adipogenesis, while at the end of hair growth, a reduction in the secretion of activators or potentially, an increase in the secretion of inhibitors of adipogenesis, results in fat lipolysis. Hair-driven cycles of dWAT remodelling are uncoupled from size changes in other adipose depots that are controlled instead by systemic metabolic demands. Rich in growth factors, dWAT reciprocally signals to hair follicles, altering the activation state of their stem cells and modulating the pace of hair regrowth. dWAT cells also facilitate skin repair following injury and infection. In response to wounding, adipose progenitors secrete repair-inducing activators, while bacteria-sensing adipocytes produce antimicrobial peptides, thus aiding innate immune responses in the skin.

Teneligliptin enhances the beneficial effects of GLP-1 in endothelial cells exposed to hyperglycemic conditions

High-glucose-induced oxidative stress contributes to cardiovascular endothelial damage in diabetes. Glucagon-like peptide 1 (GLP-1) is beneficial to endothelial cells, but its effects are diminished when cells are continuously exposed to high glucose. Teneligliptin is a dipeptidyl peptidase-4 (DPP-4) inhibitor that prevents oxidative stress, apoptosis and the metabolic memory effect. We explored the potential additive effects of Teneligliptin and GLP-1 in hyperglycemia-damaged endothelial cells. Human umbilical vein endothelial cells (HUVECs) were exposed to normal-glucose (5 mmol/L) or high-glucose (HG, 25 mmol/L) for 21 days, or to HG for 14 days followed by normal-glucose for 7 days (HM). These cells were continually treated with Teneligliptin 3.0 μmol/L, alone or in combination with an acute dose of GLP-1 50 nmol/L. DPP-4 was upregulated under hyperglycemic conditions, but Teneligliptin reduced DPP-4 expression and activity. Simultaneous Teneligliptin and GLP-1 synergistically increased the antioxidant response and reduced ROS levels in HG- and HM-exposed HUVECs. Concurrent treatment also enhanced cell proliferation, reduced apoptotic gene expression and ameliorated endoplasmic reticulum stress in HG- and HM-exposed HUVECs. Thus, long-term Teneligliptin treatment reduced DPP-4 levels and activity in HUVECs exposed to chronic hyperglycemia. Moreover, Teneligliptin enhanced the beneficial effects of GLP-1 on oxidative stress, proliferation, apoptosis and endoplasmic reticulum homeostasis.

Aging of Brown and Beige/Brite Adipose Tissue

Brown adipose tissue aging and the concomitant loss of thermogenic capacity have been linked to an inability to maintain normal energy homeostasis in late life. Similarly, the ability of white fat to convert into brite/beige adipose tissue declines. This may ultimately exacerbate the progression of age-related metabolic pathologies, such as insulin resistance and obesity. The depletion of all types of brown adipocytes during aging is well-established and has been described in rodent models as well as humans. We here review the available literature on the potential mechanisms leading to cell-autonomous and microenvironment-related aspects of brown adipocyte dysfunction. Among these, cellular senescence, mitochondrial impairment, and deteriorating changes to the local and endocrine microenvironments have been proposed. An important goal of aging research is to develop approaches that may not only extend life expectancy but also prolong health-span. These efforts may also be aimed at maintaining metabolic health throughout life by targeting brown adipocyte function.

Clinical and biochemical markers of visceral adipose tissue activity: Body mass index, visceral adiposity index, leptin, adiponectin, and matrix metalloproteinase-3. Correlation with Gleason patterns 4 and 5 at prostate biopsy

Context:

The correlation between aggressive prostate cancer and obesity mainly based on body mass index (BMI) and pathology after surgery remains controversial.

Aims:

The aim of the study was to correlate BMI, visceral adiposity index (VAI), and the plasmatic levels of leptin, adiponectin, and matrix metalloproteinase-3 (MMP-3), and biomarkers of adipose tissue function, with the detection of Gleason patterns 4 and 5 at biopsy.

Subjects and Methods:

Consecutive patients with prostate cancer at 12-core transrectal biopsy were enrolled. BMI, waist circumference (WC), blood samples to evaluate the plasmatic levels of triglycerides (TG) and high-density lipoproteins (HDL), adiponectin, leptin, and MMP-3 were obtained immediately before biopsy. The VAI was calculated according to the formula: WC/(39.68 + [1.88 × BMI]) × TG/1.03 × 1.31/HDL.

Results:

One hundred and forty-nine patients were entered. The median PSA, BMI, and VAI were 10.0 ng/ml, 27.6 kg/m², and 4.6, respectively. Gleason patterns 4 or 5 were detected in 68 (45.6%) patients; in 15 (41.7%), 31 (44.9%), and 22 (50.0%) among normal weight, overweight, and obese patients, respectively (P = 0.55). The statistical analysis did not show any significant correlation between BMI, VAI, the plasmatic levels of leptin, adiponectin, MMP-3, and the detection of Gleason patterns 4 and 5 at biopsy. A statistically significant association emerged with older age (P = 0.017) and higher PSA values (P = 0.02).

Conclusion:

We did not find any association between BMI, VAI, the plasmatic levels of adiponectin, leptin, and MMP-3 and the detection of Gleason patterns 4 and 5 at prostate biopsy.

Role of MMP-1 (-519A/G, -1607 1G/2G), MMP-3 (Lys45Glu), MMP-7 (-181A/G), and MMP-12 (-82A/G) Variants and Plasma MMP Levels on Obesity-Related Phenotypes and Microvascular Reactivity in a Tunisian Population

Aims

The impact of MMP-1 (-519A/G, -1607 1G/2G), MMP-3 Lys45Glu (A/G), MMP-7 -181A/G, and MMP-12 -82A/G variants and plasma MMP levels on obesity and microvascular reactivity in Tunisians.

Methods

Our population included 202 nonobese and 168 obese subjects. Anthropometric, biochemical, and microvascular parameters were determined according to standard protocols. PCR-RFLP and ELISA were used to determine the genetic variants and levels of MMPs, respectively.

Results

The MMP-3 45Glu (G) allele associates with higher anthropometric values and MMP-3 levels compared to AA genotype carriers (BMI (kg/m²): 30 ± 0.51 versus 27.33 ± 0.8, P = 0.004; MMP-3 levels: 7.45 (4.77–11.91) versus 5.21 (3.60–10.21) ng/ml, P = 0.006). The MMP-12 -82G allele was also associated with higher BMI values when compared to subjects carrying the AA genotype (31.41 ± 0.85 versus 28.76 ± 0.43, P < 0.001). Individuals carrying the MMP-3 45G or MMP-12 -82G variants were also associated with a higher risk for severe forms of obesity (MMP-3: OR = 1.9, P = 0.002; MMP-12: OR = 2.63, P = 0.003). Similarly, the MMP-7 -181G allele was associated with a higher MMP-7 level and an increased risk for morbid obesity when compared to AA genotype carriers (0.32 (0.31–0.60) versus 0.18 (0.17–0.24) ng/ml, P = 0.01; OR = 1.67, P = 0.02, resp.).

Conclusion

MMP-3, MMP-7, and MMP-12 polymorphisms associate with obesity risk and its severity.

Key-genes regulating the liposecretion process of mature adipocytes

White mature adipocytes (MAs) are plastic cells able to reversibly transdifferentiate toward fibroblast-like cells maintaining stem cell gene signatures. The main morphologic aspect of this transdifferentiation process, called liposecretion, is the secretion of large lipid droplets and the development of organelles necessary for exocrine secretion. There is a considerable interest in the adipocyte plastic properties involving liposecretion process, but the molecular details are incompletely explored. This review analyzes the gene expression of MAs isolated from human subcutaneous fat tissue with respect to bone marrow (BM)-derived mesenchymal stem cells (MSC) focusing on gene regulatory pathways involved into cellular morphology changes, cellular proliferation and transports of molecules through the membrane, suggesting potential ways to guide liposecretion. In particular, Wnt, MAPK/ERK, and AKT pathways were accurately described, studying up- and down-stream molecules involved. Moreover, adipogenic extra- and intra-cellular interactions were analyzed studying the role of CDH2, CDH11, ITGA5, E-Syt1, PAI-1, IGF1, and INHBB genes. Additionally, PLIN1 and PLIN2 could be key-genes of liposecretion process regulating molecules transport through the membrane. All together data demonstrated that liposecretion is regulated through a complex molecular networks that are able to respond to microenvironment signals, cytokines, and growth factors. Autocrine as well as external signaling molecules might activate liposecretion affecting adipocytes physiology.

Role of MicroRNA Regulation in Obesity-Associated Breast Cancer: Nutritional Perspectives

Breast cancer is the most common malignancy diagnosed in women, and the incidence of breast cancer is increasing every year. Obesity has been identified as one of the major risk factors for breast cancer progression. The mechanisms by which obesity contributes to breast cancer development is not yet understood; however, there are a few mechanisms counted as potential producers of breast cancer in obesity, including insulin resistance, chronic inflammation and inflammatory cytokines, adipokines, and sex hormones. Recent emerging evidence suggests that alterations in microRNA (miRNA) expressions are found in several diseases, including breast cancer and obesity; however, miRNA roles in obesity-linked breast cancer are beginning to unravel. miRNAs are thought to be potential noninvasive biomarkers for diagnosis and prognosis of cancer patients with comorbid conditions of obesity as well as therapeutic targets. Recent studies have evidenced that nutrients and other dietary factors protect against cancer and obesity through modulation of miRNA expressions. Herein, we summarize a comprehensive overview of up-to-date information related to miRNAs and their molecular targets involved in obesity-associated breast cancer. We also address the mechanisms by which dietary factors modulate miRNA expression and its protective roles in obesity-associated breast cancer. It is hoped that this review would provide new therapeutic strategies for the treatment of obesity-associated breast cancer to reduce the burden of breast cancer.

Human aqueous humor levels of transforming growth factor-β2: Association with matrix metalloproteinases/tissue inhibitors of matrix metalloproteinases

The present study aims to investigate the association of transforming growth factor-β2 (TGF-β2) and matrix metalloproteinases (MMPs), MMP-2 and MMP-3, and tissue inhibitors of matrix metalloproteinases (TIMPs), TIMP-1, TIMP-2 and TIMP-3 in the aqueous humor of patients with high myopia or cataracts. The levels of TGF-β2 and MMPs/TIMPs were measured with the Luminex xMAP Technology using commercially available Milliplex xMAP kits. The association between TGF-β2 and MMPs/TIMPs levels was analyzed using the Spearmans correlation test. The levels of TGF-β2 were identified to be positively correlated with the levels of TIMP-1 and TIMP-3 (TIMP-1: r=0.334; P=0.007; TIMP-3: r=0.309; P=0.012). The levels of MMP-2, MMP-3 and TIMP-2 did not significantly correlate with TGF-β2 levels (P>0.05). A positive correlation was identified between TGF-β2 and TIMPs in the aqueous humor of human eyes with elongated axial length. It appears that TGF-β2 stimulates the expression of TIMPs as a compensatory reaction to the development of high myopia.

Differential expression of extracellular matrix and integrin genes in the longissimus thoracis between bulls and steers and their association with intramuscular fat contents

This study was performed to compare expression of genes for extracellular matrix (ECM) components, ECM degrading factors, and integrin subunits in the longissimus thoracis (LT) between bulls and steers. Steers had lower (P<0.05) ECM component collagen type 1 α1 and collagen type 3 α1 mRNA levels than did bulls, but they had higher (P<0.05) thrombospondin 1 mRNA and protein levels. Steers had higher (P<0.01) matrix metalloproteinase (MMP) 9 mRNA levels than did bulls. Steers had higher (P<0.05) integrin α5 mRNA levels but lower (P<0.05) integrin β6 mRNA and protein levels; however, expression levels of several other integrin subunits were not different between steers and bulls. MMP9 mRNA levels were positively correlated (P<0.05) with intramuscular fat content in bull group. In conclusion, these results demonstrate that castration has moderate effects on expression of ECM components, ECM degrading factors, and integrin subunit genes in the LT.

Physical training improves visceral adipose tissue health by remodelling extracellular matrix in rats with estrogen absence: a gene expression analysis

Adipose tissue development is associated with modifications involving extracellular matrix remodelling, and metalloproteinases play a significant role in this process. Reduced circulating sexual hormones cause impacts on the size, morphology and functions of the adipose tissue, increasing susceptibility to diseases. This study investigated whether exercise training may be an alternative strategy to combat the effects promoted by estrogen decay through modulation in gene expression patterns in the extracellular matrix (ECM) of visceral adipose tissue of ovariectomized rats. Nulliparous rats (n = 40) were randomly distributed into four groups (n = 10/group): sham sedentary (Sh-S), sham resistance training (Sh-Rt), ovariectomized sedentary (Ovx-S) and ovariectomized resistance training (Ovx-Rt). The Sh-S animals did not have any type of training. The body mass and food intake, ECM gene expression, gelatinase MMP-2 activity and adipocyte area were measured. A lack of estrogen promoted an increase in body mass, food intake and the visceral, parametrial and subcutaneous adipocyte areas. The ovariectomy upregulated the expression of MMP-2, MMP-9, TGF-β, CTGF, VEGF-A and MMP-2 activity. On the other hand, resistance training decreased the body mass, food intake and the adipocyte area of the three fat depots analysed; upregulated TIMP-1, VEGF-A and MMP-2 gene expression; downregulated MMP-9, TGF-β and CTGF gene expression; and decreased the MMP-2 activity. We speculate that resistance training on a vertical ladder could play an important role in maintaining and remodelling ECM by modulation in the ECM gene expression and MMP-2 activity, avoiding its destabilization which is impaired by the lack of estrogen.

1-Deoxynojirimycin: Sources, Extraction, Analysis and Biological Functions

1-Deoxynojirimycin (DNJ), a natural polyhydroxylated piperidine alkaloid, is attracting growing attention due to its important biological functions. This paper introduces the discovery and origins of DNJ, its extraction, purification, and physiological functions in the treatment of diabetes. The mechanisms of DNJ in the inhibition of fat accumulation and tumor cell metastasis are also discussed. In addition, the prospects and challenges of DNJ for practical production are proposed. This work aims to provide technical advice on obtaining DNJ and a fuller understanding of its biological activities.

Ciliary Hedgehog Signaling Restricts Injury-Induced Adipogenesis

Injured skeletal muscle regenerates, but with age or in muscular dystrophies, muscle is replaced by fat. Upon injury, muscle-resident fibro/adipogenic progenitors (FAPs) proliferated and gave rise to adipocytes. These FAPs dynamically produced primary cilia, structures that transduce intercellular cues such as Hedgehog (Hh) signals. Genetically removing cilia from FAPs inhibited intramuscular adipogenesis, both after injury and in a mouse model of Duchenne muscular dystrophy. Blocking FAP ciliation also enhanced myofiber regeneration after injury and reduced myofiber size decline in the muscular dystrophy model. Hh signaling through FAP cilia regulated the expression of TIMP3, a secreted metalloproteinase inhibitor, that inhibited MMP14 to block adipogenesis. A pharmacological mimetic of TIMP3 blocked the conversion of FAPs into adipocytes, pointing to a strategy to combat fatty degeneration of skeletal muscle. We conclude that ciliary Hh signaling by FAPs orchestrates the regenerative response to skeletal muscle injury.

Absence of Tissue Inhibitor of Metalloproteinase-4 (TIMP4) ameliorates high fat diet-induced obesity in mice due to defective lipid absorption

Tissue inhibitor of metalloproteases (TIMPs) are inhibitors of matrix metalloproteinases (MMPs) that regulate tissue extracellular matrix (ECM) turnover. TIMP4 is highly expressed in adipose tissue, its levels are further elevated following high-fat diet, but its role in obesity is unknown. Eight-week old wild-type (WT) and Timp4-knockout (Timp4 -/-) mice received chow or high fat diet (HFD) for twelve weeks. Timp4 -/- mice exhibited a higher food intake but lower body fat gain. Adipose tissue of Timp4 -/- -HFD mice showed reduced hypertrophy and fibrosis compared to WT-HFD mice. Timp4 -/- -HFD mice were also protected from HFD-induced liver and skeletal muscle triglyceride accumulation and dyslipidemia. Timp4 -/--HFD mice exhibited reduced basic metabolic rate and energy expenditure, but increased respiratory exchange ratio. Increased free fatty acid excretion was detected in Timp4 -/--HFD compared to WT-HFD mice. CD36 protein, the major fatty acid transporter in the small intestine, increased with HFD in WT but not in Timp4 -/- mice, despite a similar rise in Cd36 mRNA in both genotypes. Consistently, HFD increased enterocyte lipid content only in WT but not in Timp4 -/- mice. Our study reveals that absence of TIMP4 can impair lipid absorption and the high fat diet-induced obesity in mice possibly by regulating the proteolytic processing of CD36 protein in the intestinal enterocytes.

AT1-receptor blockade attenuates outward aortic remodeling associated with diet-induced obesity in mice

The renin-angiotensin system (RAS) and obesity have been implicated in vascular outward remodeling, including aneurysms, but the precise mechanisms are not yet understood. We investigated the effect of the angiotensin receptor type 1 (AT1-receptor) antagonist telmisartan on aortic outward remodeling in a diet-induced obesity model in mice. C57/Black6J mice were fed either a low-fat diet (LFD) or a high-fat diet (HFD) for 14 weeks. One group of HFD mice was additionally exposed to telmisartan (3 mg/kg per day) for the last 4 weeks. HFD led to aortic outward remodeling, characterized by increased proteolysis, along with structural changes, such as fragmentation of elastic fibers and decreased elastin content. Vascular damage was associated with up-regulation of matrix metalloproteinase (MMP)-2 (MMP-2), MMP-3, MMP-12, cathepsin D, and cathepsin B. HFD aortae exhibited an enhanced inflammatory status, characterized by tumor necrosis factor α (TNF-α) and interleukin-1β (IL-1β) colocalized with adipocytes in the adventitia. HFD resulted in a significant increase in aortic dimensions, evident by ultrasound measurements. Telmisartan abolished aortic dilatation and preserved elastin content. HFD induced enhanced expression of aortic MMP-2, MMP-9, and TNF-α was abrogated by telmisartan. Adventitial proteolytic and inflammatory factors were also examined in samples from human abdominal aneurysms. The expression of TNF-α, IL-1β, and MMP-9 was higher in the adventitial fat of diseased vessels compared with healthy tissues. Finally, adipocytes treated with TNF-α showed enhanced MMP-2, MMP-3, and cathepsin D, which was prevented by telmisartan. Taken together, HFD in mice induced aortic dilatation with up-regulation of matrix degrading and inflammatory pathways similar to those seen in human aortic aneurysmatic tissue. The HFD-induced vascular pathology was reduced by AT1-receptor antagonist telmisartan.

Obesity/Type II diabetes alters macrophage polarization resulting in a fibrotic tendon healing response

Type II Diabetes (T2DM) dramatically impairs the tendon healing response, resulting in decreased collagen organization and mechanics relative to non-diabetic tendons. Despite this burden, there remains a paucity of information regarding the mechanisms that govern impaired healing of diabetic tendons. Mice were placed on either a high fat diet (T2DM) or low fat diet (lean) and underwent flexor tendon transection and repair surgery. Healing was assessed via mechanical testing, histology and changes in gene expression associated with collagen synthesis, matrix remodeling, and macrophage polarization. Obese/diabetic tendons healed with increased scar formation and impaired mechanical properties. Consistent with this, prolonged and excess expression of extracellular matrix (ECM) components were observed in obese/T2DM tendons. Macrophages are involved in both inflammatory and matrix deposition processes during healing. Obese/T2DM tendons healed with increased expression of markers of pro-inflammatory M1 macrophages, and elevated and prolonged expression of M2 macrophages markers that are involved in ECM deposition. Here we demonstrate that tendons from obese/diabetic mice heal with increased scar formation and increased M2 polarization, identifying excess M2 macrophage activity and matrix synthesis as a potential mechanism of the fibrotic healing phenotype observed in T2DM tendons, and as such a potential target to improve tendon healing in T2DM.

Genetic Predictors of ≥5% Weight Loss by Multidisciplinary Advice to Severely Obese Subjects

BACKGROUND

Weight loss success is determined by genetic factors, which may differ according to treatment strategy.

METHODS

From a multidisciplinary obesity treatment program involving dietary advice, psychological counseling, and increased physical activity, 587 subjects (68% female; 46.1 ± 12.4 years; BMI 39.9 ± 6.3) were recruited. At baseline, a blood sample was drawn for DNA isolation. Genotypes were determined for 30 polymorphisms in 25 candidate genes. The association between genotypes and weight loss was assessed after 3 months (short-term) and after 12 months of treatment (long-term). Weight loss was categorized as ≥5% or <5% of initial weight.

RESULTS

The G/G genotype of PLIN1 (rs2289487) and PLIN1 (rs2304795), the T/T genotype of PLIN1 (rs1052700), and the C/C genotype of MMP2 predicted ≥5% weight loss in the first 3 months. The C/G-G/G genotype of PPARγ (rs1801282) and the T/C genotype of TIMP4 (rs3755724) predicted ≥5% weight loss after 12 months. Subjects with the combination of PPARγ (rs1801282) C/G-G/G and TIMP4 (rs3755724) T/C lost even more weight.

CONCLUSION

Polymorphisms in genes related to regulation of fat storage and structural adaptation of the adipocytes are predictors for weight loss success with different genes being relevant for short-term and long-term weight loss success.

The fat and the bad: Mature adipocytes, key actors in tumor progression and resistance

Growing evidence has raised the important roles of adipocytes as an active player in the tumor microenvironment. In many tumors adipocytes are in close contact with cancer cells. They secrete various factors that can mediate local and systemic effects. The adipocyte-cancer cell crosstalk leads to phenotypical and functional changes of both cell types, which can further enhance tumor progression. Moreover, obesity, which is associated with an increase in adipose mass and an alteration of adipose tissue, has been established as a risk factor for cancer incidence and cancer-related mortality. In this review, we summarize the mechanisms of the adipocyte-cancer cell crosstalk in both obese and lean conditions as well as its impact on cancer cell growth, local invasion, metastatic spread and resistance to treatments. Better characterization of cancer-associated adipocytes and the key molecular events in the adipocyte-cancer cell crosstalk will provide insights into tumor biology and suggest efficient therapeutic opportunities.

Exosome-Like Vesicles Derived from Adipose Tissue Provide Biochemical Cues for Adipose Tissue Regeneration

There is an emerging need for soft tissue replacements in the field of reconstructive surgery for the treatment of congenital deformities, posttraumatic repair, and cancer rehabilitation. Previous studies have shown that the bioactive adipose tissue extract can induce adipogenesis without additional stem cells or growth factors. In this study, we innovatively investigated whether exosome-like vesicles derived from adipose tissue (ELV-AT) could direct stem cell differentiation and trigger adipose tissue regeneration. In vitro, ELV-AT can induce adipogenesis of adipose-derived stem cells and promote proliferation, migration, and angiogenic potential of the aorta endothelial cells. In vivo, ELV-AT were transplanted to a chamber on the back of nude mice and neoadipose tissues were formed. Our findings indicated that ELV-AT could be used as a cell-free therapeutic approach for adipose tissue regeneration.