An early inflammatory gene profile in visceral adipose tissue in children

Decoding visceral adipose tissue molecular signatures in obesity and insulin resistance: a multi-omics approach

OBJECTIVE

Obesity-associated insulin resistance (IR) is responsible for considerable morbidity and mortality globally. Despite vast genomic data, many areas, from pathogenesis to management, still have significant knowledge gaps. We aimed to characterize visceral adipose tissue (VAT) in obesity and IR through a multi-omics approach.

METHODS

We procured data on VAT samples from the Gene Expression Omnibus (GEO) for the following two groups: 1) populations with obesity (n = 34) versus those without (n = 26); and 2) populations with obesity and IR (n = 15) versus those with obesity but without IR (n = 15). Gene set enrichment, protein-protein interaction network construction, hub gene identification, and drug-gene interactions were performed, followed by regulatory network prediction involving transcription factors (TFs) and microRNAs (miRNAs).

RESULTS

Interleukin signaling pathways, cellular differentiation, and regulation of immune response revealed a significant cross talk between VAT and the immune system. Other findings include cancer pathways, neurotrophin signaling, and aging. A total of 10 hub genes, i.e., STAT1, KLF4, DUSP1, EGR1, FOS, JUN, IL2, IL6, MMP9, and FGF9, 24 TFs, and approved hub gene-targeting drugs were obtained. A total of 10 targeting miRNAs (e.g., hsa-miR-155-5p, hsa-miR-34a-5p) were associated with obesity and IR-related pathways.

CONCLUSIONS

Our multi-omics integration method revealed hub genes, TFs, and miRNAs that can be potential targets for investigation in VAT-related inflammatory processes and IR, therapeutic management, and risk stratifications.

Molecular and cellular mechanisms of chemoresistance in paediatric pre-B cell acute lymphoblastic leukaemia

Paediatric patients with relapsed B cell acute lymphoblastic leukaemia (B-ALL) have poor prognosis, as relapse-causing clones are often refractory to common chemotherapeutics. While the molecular mechanisms leading to chemoresistance are varied, significant evidence suggests interactions between B-ALL blasts and cells within the bone marrow microenvironment modulate chemotherapy sensitivity. Importantly, bone marrow mesenchymal stem cells (BM-MSCs) and BM adipocytes are known to support B-ALL cells through multiple distinct molecular mechanisms. This review discusses the contribution of integrin-mediated B-ALL/BM-MSC signalling and asparagine supplementation in B-ALL chemoresistance. In addition, the role of adipocytes in sequestering anthracyclines and generating a BM niche favourable for B-ALL survival is explored. Furthermore, this review discusses the role of BM-MSCs and adipocytes in promoting a quiescent and chemoresistant B-ALL phenotype. Novel treatments which target these mechanisms are discussed herein, and are needed to improve dismal outcomes in patients with relapsed/refractory disease.

Identification and Validation of CXCL2 as a Key Gene for Childhood Obesity

This study aims to identify the key genes and their regulatory networks by bioinformatics, increasing understanding of childhood obesity. The data comes from the GEO and Immport database. The immune microenvironment was explored in GSE104815. Key genes were identified by intersection of DEGs with the immune gene set. Enrichment analysis revealed gene-related functions and correlation analysis explored the relationship. Regulatory networks were constructed based on miRcode, TarBase and TargetScan databases. GSE29718 was used to validate our findings. Intercellular communication and cell differentiation trends were further explored using single-cell data from GSE153643. Based on our research, the immune microenvironment in the obese group showed higher immune infiltration. We found 962 DEGs and CXCL2 was identified as the key gene. The co-regulatory network of lncRNA-miRNA-mRNA suggested that obtaining TM4SF19-AS1, GUSBP11, AC105020.1, LINC00189, COL4A2-AS2, VIPR1-AS1 and LINC00242 may regulate CXCL2 (r > 0.9 and P < 0.01). Differential expression of CXCL2 was validated in GSE29718 (P < 0.05) and CXCL2 was identified as a biomarker for childhood obesity (AUC = 0.885). GSVA enrichment analysis revealed many pathways of high group obtaining the TNF-α signaling via NF-κB pathway and interferon γ response pathway. In GSE153643, 11 cell types were identified and CXCL2 was highly expressed in monocyte, macrophage, endothelial cell and pericyte. In CXCL2 high expressing macrophages, there was a tendency for cells to polarize toward M1 macrophages (P < 0.05). In summary, we identified CXCL2 as a potential biomarker of childhood obesity. The development of childhood obesity may be associated with the activation of immune infiltration of macrophage M1 polarization by CXCL2 expression.

Inactivation of Minar2 in mice hyperactivates mTOR signaling and results in obesity

OBJECTIVE

Obesity is a complex disorder and is linked to chronic diseases such as type 2 diabetes. Major intrinsically disordered NOTCH2-associated receptor2 (MINAR2) is an understudied protein with an unknown role in obesity and metabolism. The purpose of this study was to determine the impact of Minar2 on adipose tissues and obesity.

METHOD

We generated Minar2 knockout (KO) mice and used various molecular, proteomic, biochemical, histopathology, and cell culture studies to determine the pathophysiological role of Minar2 in adipocytes.

RESULTS

We demonstrated that the inactivation of Minar2 results in increased body fat with hypertrophic adipocytes. Minar2 KO mice on a high-fat diet develop obesity and impaired glucose tolerance and metabolism. Mechanistically, Minar2 interacts with Raptor, a specific and essential component of mammalian TOR complex 1 (mTORC1) and inhibits mTOR activation. mTOR is hyperactivated in the adipocytes deficient for Minar2 and over-expression of Minar2 in HEK-293 cells inhibited mTOR activation and phosphorylation of mTORC1 substrates, including S6 kinase, and 4E-BP1.

CONCLUSION

Our findings identified Minar2 as a novel physiological negative regulator of mTORC1 with a key role in obesity and metabolic disorders. Impaired expression or activation of MINAR2 could lead to obesity and obesity-associated diseases.

Transcriptome Analyses of Adipose Tissue Samples Identify EGFL6 as a Candidate Gene Involved in Obesity-Related Adipose Tissue Dysfunction in Children

Obesity develops early in childhood and is accompanied by early signs of adipose tissue (AT) dysfunction and metabolic disease in children. In order to analyse the molecular processes during obesity-related AT accumulation in children, we investigated genome-wide expression profiles in AT samples, isolated adipocytes, and stromal vascular fraction (SVF) cells and assessed their relation to obesity as well as biological and functional AT parameters. We detected alterations in gene expression associated with obesity and related parameters, i.e., BMI SDS, adipocyte size, macrophage infiltration, adiponectin, and/or leptin. While differential gene expression in AT and adipocytes shared an enrichment in metabolic pathways and pathways related to extracellular structural organisation, SVF cells showed an overrepresentation in inflammatory pathways. In adipocytes, we found the strongest positive association for epidermal growth factor-like protein 6 (EGFL6) with adipocyte hypertrophy. EGFL6 was also upregulated during in vitro adipocyte differentiation. In children, EGFL6 expression was positively correlated to parameters of AT dysfunction and metabolic disease such as macrophage infiltration into AT, hs-CRP, leptin levels, and HOMA-IR. In conclusion, we provide evidence for early alterations in AT gene expression related to AT dysfunction in children and identified EGFL6 as potentially being involved in processes underlying the pathogenesis of metabolic disease.

Innate PD-L1 limits T cell-mediated adipose tissue inflammation and ameliorates diet-induced obesity

Obesity has become a major health problem in the industrialized world. Immune regulation plays an important role in adipose tissue homeostasis; however, the initial events that shift the balance from a noninflammatory homeostatic environment toward inflammation leading to obesity are poorly understood. Here, we report a role for the costimulatory molecule programmed death-ligand 1 (PD-L1) in the limitation of diet-induced obesity. Functional ablation of PD-L1 on dendritic cells (DCs) using conditional knockout mice increased weight gain and metabolic syndrome during diet-induced obesity, whereas PD-L1 expression on type 2 innate lymphoid cells (ILC2s), T cells, and macrophages was dispensable for obesity control. Using in vitro cocultures, DCs interacted with T cells and ILC2s via the PD-L1:PD-1 axis to inhibit T helper type 1 proliferation and promote type 2 polarization, respectively. A role for PD-L1 in adipose tissue regulation was also shown in humans, with a positive correlation between PD-L1 expression in visceral fat of people with obesity and elevated body weight. Thus, we define a mechanism of adipose tissue homeostasis controlled by the expression of PD-L1 by DCs, which may be a clinically relevant finding with regard to immune-related adverse events during immune checkpoint inhibitor therapy.

Pleiotropic genetic influence on birth weight and childhood obesity

Childhood obesity is a global public health problem. Understanding the molecular mechanisms that underlie early origins of childhood obesity can facilitate interventions. Consistent phenotypic and genetic correlations have been found between childhood obesity traits and birth weight (a proxy for in-utero growth), suggesting shared genetic influences (pleiotropy). We aimed to (1) investigate whether there is significant shared genetic influence between birth weight and childhood obesity traits, and (2) to identify genetic loci with shared effects. Using a statistical approach that integrates summary statistics and functional annotations for paired traits, we found strong evidence of pleiotropy (P < 3.53 × 10^–127) and enrichment of functional annotations (P < 1.62 × 10^–39) between birth weight and childhood body mass index (BMI)/obesity. The pleiotropic loci were enriched for regulatory features in skeletal muscle, adipose and brain tissues and in cell lines derived from blood lymphocytes. At 5% false discovery rate, 6 loci were associated with birth weight and childhood BMI and 13 loci were associated with birth weight and childhood obesity. Out of these 19 loci, one locus (EBF1) was novel to childhood obesity and one locus (LMBR1L) was novel to both birth weight and childhood BMI/obesity. These findings give evidence of substantial shared genetic effects in the regulation of both fetal growth and childhood obesity.

Is There A Causal Relationship between Childhood Obesity and Acute Lymphoblastic Leukemia? A Review

Childhood obesity is a growing epidemic with numerous global health implications. Over the past few years, novel insights have emerged about the contribution of adult obesity to cancer risk, but the evidence base is far more limited in children. While pediatric patients with acute lymphoblastic leukemia (ALL) are at risk of obesity, it is unclear if there are potential causal mechanisms by which obesity leads to ALL development. This review explores the endocrine, metabolic and immune dysregulation triggered by obesity and its potential role in pediatric ALL's genesis. We describe possible mechanisms, including adipose tissue attraction and protection of lymphoblasts, and their impact on ALL chemotherapies' pharmacokinetics. We also explore the potential contribution of cytokines, growth factors, natural killer cells and adipose stem cells to ALL initiation and propagation. While there are no current definite causal links between obesity and ALL, critical questions persist as to whether the adipose tissue microenvironment and endocrine actions can play a causal role in childhood ALL, and there is a need for more research to address these questions.

Greater Visceral Fat but No Difference in Measures of Total Body Fat in Ambulatory Children With Spastic Cerebral Palsy Compared to Typically Developing Children

BACKGROUND

Individuals with cerebral palsy (CP) are at increased risk for obesity and obesity-related complications. Studies of total body fat in those with CP are inconsistent and studies of abdominal fat are lacking in children with CP. The objective of this study was to determine if ambulatory children with spastic CP have greater central adiposity compared to typically developing children.

METHODOLOGY

Eighteen ambulatory children with spastic CP (n = 5 girls; 8.6 ± 2.9 yr) and 18 age-, sex-, and race-matched typically developing children (controls; 8.9 ± 2.1 yr) participated in this cross-sectional study. Children with CP were classified as I or II using the Gross Motor Function Classification System. Dual-energy X-ray absorptiometry assessed body composition, including total body, trunk and abdominal fat mass, fat-free mass, fat mass index (FMI), and fat-free mass index (FFMI).

RESULTS

There were no group differences in fat mass, fat-free mass, FMI, and FFMI in the total body, fat mass, fat-free mass, and FFMI in the trunk, or fat mass, visceral fat mass, and subcutaneous fat mass in the abdomen (p > 0.05). Compared to controls, children with CP had higher trunk FMI, abdominal FMI, and visceral FMI (p < 0.05). Although marginally insignificant (p = 0.088), children with CP had higher subcutaneous FMI.

CONCLUSIONS

Ambulatory children with spastic CP have elevated central adiposity, especially in the visceral region, despite no differences in measures of total body fat. How this relates to cardiometabolic disease progression in those with CP requires further investigation.

Investigation of the adolescent female breast transcriptome and the impact of obesity

Background

Early life environmental exposures affect breast development and breast cancer risk in adulthood. The breast is particularly vulnerable during puberty when mammary epithelial cells proliferate exponentially. In overweight/obese (OB) women, inflammation increases breast aromatase expression and estrogen synthesis and promotes estrogen-receptor (ER)-positive breast cancer. In contrast, recent epidemiological studies suggest that obesity during childhood decreases future breast cancer risk. Studies on environmental exposures and breast cancer risk have thus far been limited to animal models. Here, we present the first interrogation of the human adolescent breast at the molecular level and investigate how obesity affects the immature breast.

Methods

We performed RNA-seq in 62 breast tissue samples from adolescent girls/young women (ADOL; mean age 17.8 years) who underwent reduction mammoplasty. Thirty-one subjects were non-overweight/obese (NOB; mean BMI 23.4 kg/m²) and 31 were overweight/obese (OB; BMI 32.1 kg/m²). We also compared our data to published mammary transcriptome datasets from women (mean age 39 years) and young adult mice, rats, and macaques.

Results

The ADOL breast transcriptome showed limited (30%) overlap with other species, but 88% overlap with adult women for the 500 most highly expressed genes in each dataset; only 43 genes were shared by all groups. In ADOL, there were 120 differentially expressed genes (DEG) in OB compared with NOB samples (p_adj < 0.05). Based on these DEG, Ingenuity Pathway Analysis (IPA) identified the cytokines CSF1 and IL-10 and the chemokine receptor CCR2 as among the most highly activated upstream regulators, suggesting increased inflammation in the OB breast. Classical ER targets (e.g., PR, AREG) were not differentially expressed, yet IPA identified the ER and PR and growth factors/receptors (VEGF, HGF, HER3) and kinases (AKT1) involved in hormone-independent ER activation as activated upstream regulators in OB breast tissue.

Conclusions

These studies represent the first investigation of the human breast transcriptome during late puberty/young adulthood and demonstrate that obesity is associated with a transcriptional signature of inflammation which may augment estrogen action in the immature breast microenvironment. We anticipate that these studies will prompt more comprehensive cellular and molecular investigations of obesity and its effect on the breast during this critical developmental window.

Haptoglobin Phenotypes Are Associated with the Postload Glucose and Insulin Levels in Pediatric Obesity

PURPOSE

Haptoglobin (Hp) is a protein involved in the acute-phase reaction of inflammation. Humans have three major phenotypes (Hp1-1, Hp1-2, and Hp2-2). Several studies have shown altered Hp regulation in adults with obesity and metabolic alterations. The Hp2-2 phenotype is associated with a high cardiovascular risk. Our aim was to investigate if Hp levels and the Hp2-2 phenotype are associated with glucose metabolism in pediatric obesity.

METHODS

We retrospectively studied 192 participants (92 males and 100 females), aged 4-18 years. Clinical and biochemical data were collected. The Hp phenotype (Hp1-1, Hp1-2, and Hp2-2) was identified through Western immunoblot.

RESULTS

Subjects carrying Hp1-1, Hp1-2, and Hp2-2 phenotypes were 13.6, 50.8, and 35.6%, respectively. Hp serum, fasting glucose, and insulin levels, as well as HOMA-IR, were similar among groups. Postload glucose and insulin levels (as insulin AUC) were progressively higher from the Hp1-1 to Hp2-2 phenotype.

CONCLUSION

To our knowledge, this is the first study on Hp phenotypes conducted in a pediatric population with obesity. We showed that the presence of Hp2 allele is associated with a worse response of glucose load in terms of both glucose and insulin levels. Thus, the Hp2-2 phenotype could predispose in pediatrics, at the same degree of obesity, to a worse glycemic and insulinemic compensation.

Long non-coding RNA HCP5 serves as a ceRNA sponging miR-17-5p and miR-27a/b to regulate the pathogenesis of childhood obesity via the MAPK signaling pathway

Background This study aimed to investigate the completing endogenous RNA (ceRNA) network involved in childhood obesity. Methods The microarray dataset GSE9624 was downloaded from the Gene Expression Omnibus (GEO) database. Differentially expressed long non-coding RNAs (lncRNAs) (DELs) and messenger RNAs (DEMs) were isolated between the childhood obesity and non-obesity tissue samples. Then, Gene Ontology (GO) functional and the Kyoto Encyclopedia of Genes and Genomes (KEGG) pathway analyses of isolated DEMs were performed. DELs and DEMs targeted miRNAs were predicted to construct a ceRNA regulatory network. Finally, critical lncRNAs were validated in another dataset. Results A total of 1257 differentially expressed RNAs were screened, including 28 lncRNAs and 1229 mRNAs. In addition, these RNAs were mainly involved in defense response, cell cycle, mitogen-activated protein kinase (MAPK) signaling pathway, apoptosis, etc. Three lncRNAs (human leukocyte antigen complex 5 [HCP5], long intergenic non-protein coding RNA 839 [LINC00839] and receptor activity modifying protein 2 [RAMP2-AS1]) and two related miRNAs (hsa-miR-17-5p and hsa-miR-27a/b-3p) were identified as key RNAs in childhood obesity. Specifically, lncRNA HCP5 interacted with miR-17-5p and miR-27a/b to regulate nemo-like kinase (NLK) and Ras-related protein 2 (RRAS2) via the MAPK signaling pathway. Finally, four genes (RRAS2, NLK, bcl2/adenovirus E1B protein-interacting protein 3 [BNIP3] and phorbol-12-myristate-13-acetate-induced protein 1 [PMAIP1]) targeted by miRNAs were predicted as critical genes and might be novel diagnostic biomarkers of childhood obesity. Conclusions lncRNA HCP5 could serve as a ceRNA sponging miR-17-5p and miR-27a/b to regulate the pathogenesis of childhood obesity via NLK and RRAS2 in the MAPK signaling pathway.

Total and regional body fat status among children and young people with cerebral palsy: A scoping review

The purpose of our scoping review was to determine if children and young people with cerebral palsy (CP) have elevated total or regional body fat compared to children and young people without CP. Databases (Ovid MEDLINE, Embase Ovid, CINHAL and Scopus) were systematically searched from 1 January 1993 to 7 December 2018 in order to identify articles that compared weight status, total body fat or regional body fat (eg, abdominal) between children and young people (0-21 years) with and without CP. Extracted data included country, subject characteristics, group sample sizes and matching strategies, methods/measures for weight status/fat depot, fat depot(s) assessed and key findings. Twenty-two studies were included. Of these, 19 studies examined total body fat; the most common method was use of anthropometrics and the more common measures were body mass index and skin-fold thickness. Twelve studies examined at least one regional fat depot; the most common method was use of anthropometrics and the most common measure was skin-fold thickness. Findings were inconsistent across studies. Further, among 10 studies that examined total and regional body fat depots, 8 found differences across fat depots within the same children and young people (eg, no difference in total body fat but higher abdominal fat). This review provides a summary of inconsistent findings from published studies on body fat comparisons between children and young people with vs without CP, highlights limitations for evaluating body fat for children with CP and discusses future research directions.

Osteogenesis depends on commissioning of a network of stem cell transcription factors that act as repressors of adipogenesis

Mesenchymal (stromal) stem cells (MSCs) constitute populations of mesodermal multipotent cells involved in tissue regeneration and homeostasis in many different organs. Here we performed comprehensive characterization of the transcriptional and epigenomic changes associated with osteoblast and adipocyte differentiation of human MSCs. We demonstrate that adipogenesis is driven by considerable remodeling of the chromatin landscape and de novo activation of enhancers, whereas osteogenesis involves activation of preestablished enhancers. Using machine learning algorithms for in silico modeling of transcriptional regulation, we identify a large and diverse transcriptional network of pro-osteogenic and antiadipogenic transcription factors. Intriguingly, binding motifs for these factors overlap with SNPs related to bone and fat formation in humans, and knockdown of single members of this network is sufficient to modulate differentiation in both directions, thus indicating that lineage determination is a delicate balance between the activities of many different transcription factors.

Nonalcoholic fatty liver disease and gastric bypass surgery regulate serum and hepatic levels of pyruvate kinase isoenzyme M2

Treatment of nonalcoholic fatty liver disease (NAFLD) focuses on the underlying metabolic syndrome, and Roux-en-Y gastric bypass surgery (RYGB) remains one of the most effective options. In rodents and human patients, RYGB induces an increase in the gene and protein expression levels of the M2 isoenzyme of pyruvate kinase (PKM2) in the jejunum. Since PKM2 can be secreted in the circulation, our hypothesis was that the circulating levels of PKM2 increase after RYGB. Our data, however, revealed an unexpected finding and a potential new role of PKM2 for the natural history of metabolic syndrome and NAFLD. Contrary to our initial hypothesis, RYGB-treated patients had decreased PKM2 blood levels compared with a well-matched group of patients with severe obesity before RYGB. Interestingly, PKM2 serum concentration correlated with body mass index before but not after the surgery. This prompted us to evaluate other potential mechanisms and sites of PKM2 regulation by the metabolic syndrome and RYGB. We found that in patients with NAFLD and nonalcoholic steatohepatitis (NASH), the liver had increased PKM2 expression levels, and the enzyme appears to be specifically localized in Kupffer cells. The study of murine models of metabolic syndrome and NASH replicated this pattern of expression, further suggesting a metabolic link between hepatic PKM2 and NAFLD. Therefore, we conclude that PKM2 serum and hepatic levels increase in both metabolic syndrome and NAFLD and decrease after RYGB. Thus, PKM2 may represent a new target for monitoring and treatment of NAFLD.

Screening of exosomal miRNAs derived from subcutaneous and visceral adipose tissues: Determination of targets for the treatment of obesity and associated metabolic disorders

Exosomal micro (mi)RNAs have been suggested to have important roles in abdominal obesity, and to be associated with metabolic alterations via posttranscriptional regulation of target genes. However, exosomal miRNA profiles in subcutaneous adipose tissue (SAT) and visceral adipose tissue (VAT) have rarely been investigated. In the present study, microarray data were obtained from the Gene Expression Omnibus database with the following accession numbers: GSE68885 (exosomal miRNAs in SAT obtained from seven patients with obesity and five lean patients), GSE50574 (exosomal miRNAs in VAT obtained from seven patients with obesity and five lean patients) and GSE29718 [mRNAs in SAT (obtained from seven patients with obesity and eight lean patients) and VAT (obtained from three patients with obesity and two lean patients)]. Differentially expressed (DE)‑miRNAs and differentially expressed genes (DEGs) were identified using the Linear Models for Microarray Data method, and mRNA targets of DE‑miRNAs were predicted using the miRWalk2.0 database. Potential functions of DE‑miRNA target genes were determined using the Database for Annotation, Visualization and Integrated Discovery. As a result, 10 exosomal DE‑miRNAs were identified in SAT between patients with obesity and lean patients, while 58 DE‑miRNAs were identified in VAT between patients with obesity and lean patients. miRNA (miR)‑4517 was revealed to be a downregulated exosomal miRNA between SAT and VAT, while the other DE‑miRNAs were SAT‑(e.g. hsa‑miR‑3156‑5p and hsa‑miR‑4460) or VAT‑(e.g. hsa‑miR‑582‑5p, hsa‑miR‑566 and miR‑548) specific. Following overlapping with the target genes of DE‑miRNAs, only one DEG [cluster of differentiation 86 (CD86)] was identified in SAT samples, whereas 25 DEGs (e.g. fibroblast growth factor 2 (FGF2), FOS like 2, AP‑1 transcription factor subunit (FOSL2); and adenosine monophosphate deaminase 3 (AMPD3)] were identified in VAT samples. CD86 was revealed to be regulated by hsa‑miR‑3156‑5p; whereas FGF2, FOSL2 and AMPD3 were revealed to be regulated by hsa‑miR‑582‑5p, hsa‑miR‑566 and miR‑548, respectively. Functional enrichment analysis demonstrated that these target genes may be associated with inflammation. In conclusion, exosomal miRNAs may represent underlying therapeutic targets for the treatment of abdominal obesity and metabolic disorders via regulation of inflammatory genes.

Enhancer-driven transcriptional regulation is a potential key determinant for human visceral and subcutaneous adipocytes

Obesity is characterized by the excess of body fat leading to impaired health. Abdominal fat is particularly harmful and is associated with cardiovascular and metabolic diseases and cancer. In contrast, subcutaneous fat is generally considered less detrimental. The mechanisms that establish the cellular characteristics of these distinct fat types in humans are not fully understood. Here, we explored whether differences of their gene regulatory mechanisms can be investigated in vitro. For this purpose, we in vitro differentiated human visceral and subcutaneous pre-adipocytes into mature adipocytes and obtained their gene expression profiles and genome-wide H3K4me3, H3K9me3 and H3K27ac patterns. Subsequently, we compared those data with public gene expression data from visceral and subcutaneous fat tissues. We found that the in vitro differentiated adipocytes show significant differences in their transcriptional landscapes, which correlate with biological pathways that are characteristic for visceral and subcutaneous fat tissues, respectively. Unexpectedly, visceral adipocyte enhancers are rich on motifs for transcription factors involved in the Hippo-YAP pathway, cell growth and inflammation, which are not typically associated with adipocyte function. In contrast, enhancers of subcutaneous adipocytes show enrichment of motifs for common adipogenic transcription factors, such as C/EBP, NFI and PPARγ, implicating substantially disparate gene regulatory networks in visceral and subcutaneous adipocytes. Consistent with the role in obesity, predominantly the histone modification pattern of visceral adipocytes is linked to obesity-associated diseases. Thus, this work suggests that the properties of visceral and subcutaneous fat tissues can be studied in vitro and provides preliminary insights into their gene regulatory processes.

Adipocytes Sequester and Metabolize the Chemotherapeutic Daunorubicin

Obesity is associated with poorer outcome for many cancers. Previously, we observed that adipocytes protect acute lymphoblastic leukemia (ALL) cells from the anthracycline, daunorubicin. In this study, it is determined whether adipocytes clear daunorubicin from the tumor microenvironment (TME). Intracellular daunorubicin concentrations were evaluated using fluorescence. Daunorubicin and its largely inactive metabolite, daunorubicinol, were analytically measured in media, cells, and tissues using liquid chromatography/mass spectrometry (LC/MS). Expression of daunorubicin-metabolizing enzymes, aldo-keto reductases (AKR1A1, AKR1B1, AKR1C1, AKR1C2, AKR1C3, and AKR7A2) and carbonyl reductases (CBR1, CBR3), in human adipose tissue, were queried using public databases and directly measured by quantitative PCR (qPCR) and immunoblot. Adipose tissue AKR activity was measured by colorimetric assay. Adipocytes absorbed and efficiently metabolized daunorubicin to daunorubicinol, reducing its antileukemia effect in the local microenvironment. Murine studies confirmed adipose tissue conversion of daunorubicin to daunorubicinol in vivo Adipocytes expressed high levels of AKR and CBR isoenzymes that deactivate anthracyclines. Indeed, adipocyte protein levels of AKR1C1, AKR1C2, and AKR1C3 are higher than all other human noncancerous cell types. To our knowledge, this is the first demonstration that adipocytes metabolize and inactivate a therapeutic drug. Adipocyte-mediated daunorubicin metabolism reduces active drug concentration in the TME. These results could be clinically important for adipocyte-rich cancer microenvironments such as omentum, breast, and marrow. As AKR and CBR enzymes metabolize several drugs, and can be expressed at higher levels in obese individuals, this proof-of-principle finding has important implications across many diseases.Implications: Adipocyte absorption and metabolism of chemotherapies can reduce cytotoxicity in cancer microenvironments, potentially contributing to poorer survival outcomes. Mol Cancer Res; 15(12); 1704-13. ©2017 AACR.

Identification of key genes and pathways associated with obesity in children

The present study aimed to identify potential key genes and pathways in obese children in order to explore possible molecular mechanisms associated with child obesity. The array dataset GSE29718 was downloaded from the Gene Expression Omnibus database. Subcutaneous adipose tissue samples derived from 7 obese children and 8 lean children were selected for the analysis. Differentially expressed genes (DEGs) in samples from obese children compared with those from lean children were analyzed by the limma package. Gene ontology (GO) annotation, Kyoto Encyclopedia of Genes and Genomes and Reactome pathway enrichment analyses for up and downregulated genes were performed. A protein-protein interaction (PPI) network was constructed with Cytoscape software and important genes associated with obesity were determined using IRegulon. A total of 199 DEGs (79 up and 120 downregulated genes) were identified in the samples of obese children compared with those from lean children. The PPI network was established with 103 nodes and 147 protein pairs. Matrix metalloproteinase 9 (MMP9) and acetyl-CoA carboxylase β (ACACB) were identified as hub genes in the PPI network and may therefore be marker genes for child obesity. In addition, upregulated DEGs were enriched in Reactome pathways associated with the immune system. Besides, MMP9 was upregulated in immune system processes as a GO term in the category Biological Processes. The results of the present study indicated that MMP9, ACACB and immune system pathways may have a significant role in child obesity.

The initiation of metabolic inflammation in childhood obesity

An understanding of the events that initiate metabolic inflammation (metainflammation) can support the identification of targets for preventing metabolic disease and its negative effects on health. There is ample evidence demonstrating that the initiating events in obesity-induced inflammation start early in childhood. This has significant implications on our understanding of how early life events in childhood influence adult disease. In this Review we frame the initiating events of metainflammation in the context of child development and discuss what this reveals about the mechanisms by which this unique form of chronic inflammation is initiated and sustained into adulthood.

The Multifaceted Haptoglobin in the Context of Adipose Tissue and Metabolism

Obesity is a low chronic inflammatory state because several inflammatory factors are increased in obese subjects, this having important implications for the onset of obesity-associated complications. The source of most of these inflammatory molecules is white adipose tissue (WAT), which upon excessive weight gain, becomes infiltrated with macrophages and lymphocytes and undergoes important changes in its gene expression. Haptoglobin (Hp), a typical marker of inflammation in clinical practice, main carrier of free hemoglobin, and long known to be part of the hepatic acute phase response, perfectly sits in the intersection between obesity and inflammation: it is expressed by adipocytes and its abundance in WAT and in plasma positively relates to the degree of adiposity. In the present review, we will analyze causes and consequences of Hp expression and regulation in WAT and how these relate to the obesity/inflammation paradigm and comorbidities.

Zinc transporter Slc39a14 regulates inflammatory signaling associated with hypertrophic adiposity

Zinc is a signaling molecule in numerous metabolic pathways, the coordination of which occurs through activity of zinc transporters. The expression of zinc transporter Zip14 (Slc39a14), a zinc importer of the solute carrier 39 family, is stimulated under proinflammatory conditions. Adipose tissue upregulates Zip14 during lipopolysaccharide-induced endotoxemia. A null mutation of Zip14 (KO) revealed that phenotypic changes in adipose include increased cytokine production, increased plasma leptin, hypertrophied adipocytes, and dampened insulin signaling. Adipose tissue from KO mice had increased levels of preadipocyte markers, lower expression of the differentiation marker (PPARγ), and activation of NF-κB and STAT3 pathways. Our overall hypothesis was that ZIP14 would play a role in adipocyte differentiation and inflammatory obesity. Global Zip14 KO causes systemic endotoxemia. The observed metabolic changes in adipose metabolism were reversed when oral antibiotics were administrated, indicating that circulating levels of endotoxin were in part responsible for the adipose phenotype. To evaluate a mechanism, 3T3-L1 cells were differentiated into adipocytes and treated with siRNA to knock down Zip14. These cells had an impaired ability to mobilize zinc, which caused dysregulation of inflammatory pathways (JAK2/STAT3 and NF-κB). The Zip14 deletion may limit the availability of intracellular zinc, yielding the unique phenotype of inflammation coupled with hypertrophy. Taken together, these results suggest that aberrant zinc distribution observed with Zip14 ablation impacts adipose cytokine production and metabolism, ultimately increasing fat deposition when exposed to endotoxin. To our knowledge, this is the first investigation into the mechanistic role of ZIP14 in adipose tissue regulation and metabolism.

Establishing Waist-to-Height Ratio Standards from Criterion-Referenced BMI Using ROC Curves in Low-Income Children

The purpose of this study was to establish health-related waist-to-height ratio (WHtR) cut-points associating with FITNESSGRAM's body mass index (BMI) criterion-referenced standards in low-income children. A secondary aim was to examine the classification agreement between the derived WHtR cut-points and various cardiometabolic blood markers using current recommendations. Participants were 219 children from low-income schools (mean age = 10.5 ± 0.6 years). Waist circumference, height, weight, and cardiometabolic blood markers were collected in a fasting state before school hours. Receiver operating characteristic (ROC) curves were used to determine WHtR cut-points that associated with a child meeting FITNESSGRAM's age- and sex-specific criterion-referenced standards for BMI. The derived WHtR cut-point was 0.50 (AUC = 0.89, p < 0.001; sensitivity = 0.86, specificity = 0.82, and accuracy = 84.3%). Classification agreement using the derived WHtR cut-point with various blood marker standards was statistically significant but considered weak to fair (kappa 0.14-0.34, agreement = 59%-67%, and p < 0.01). The WHtR cut-point of 0.50 can be used with strong accuracy to distinguish low-income children who met FITNESSGRAM's criterion-referenced standards for body composition; however, the evidence was weaker for its use in distinguishing low-income children meeting specific cardiometabolic blood marker recommendations.

Rapid Alterations in Perirenal Adipose Tissue Transcriptomic Networks with Cessation of Voluntary Running

In maturing rats, the growth of abdominal fat is attenuated by voluntary wheel running. After the cessation of running by wheel locking, a rapid increase in adipose tissue growth to a size that is similar to rats that have never run (i.e. catch-up growth) has been previously reported by our lab. In contrast, diet-induced increases in adiposity have a slower onset with relatively delayed transcriptomic responses. The purpose of the present study was to identify molecular pathways associated with the rapid increase in adipose tissue after ending 6 wks of voluntary running at the time of puberty. Age-matched, male Wistar rats were given access to running wheels from 4 to 10 weeks of age. From the 10^th to 11^th week of age, one group of rats had continued wheel access, while the other group had one week of wheel locking. Perirenal adipose tissue was extracted, RNA sequencing was performed, and bioinformatics analyses were executed using Ingenuity Pathway Analysis (IPA). IPA was chosen to assist in the understanding of complex ‘omics data by integrating data into networks and pathways. Wheel locked rats gained significantly more fat mass and significantly increased body fat percentage between weeks 10–11 despite having decreased food intake, as compared to rats with continued wheel access. IPA identified 646 known transcripts differentially expressed (p < 0.05) between continued wheel access and wheel locking. In wheel locked rats, IPA revealed enrichment of transcripts for the following functions: extracellular matrix, macrophage infiltration, immunity, and pro-inflammatory. These findings suggest that increases in visceral adipose tissue that accompanies the cessation of pubertal physical activity are associated with the alteration of multiple pathways, some of which may potentiate the development of pubertal obesity and obesity-associated systemic low-grade inflammation that occurs later in life.

Modulating the Genomic Programming of Adipocytes

The ability to modify the transcriptional program in response to external signals provides a way for mammalian cells to alter their biological fate and properties, thereby adapting to changes in the environment. Adipocytes are excellent examples of differentiated cells that possess a striking transcriptional plasticity when exposed to physiological and metabolic stimuli. In our work, we have focused on understanding the processes responsible for modulating the genomic programming in response to different external signals. Thus, we have shown that browning of human adipocytes with rosiglitazone, an antidiabetic agonist of the key adipocyte transcription factor peroxisome proliferator-activated receptor γ (PPARγ), involves redistribution of PPARγ binding to form browning-selective PPARγ super-enhancers that drive expression of key browning genes. These include genes encoding transcriptional regulators, such as Krüppel-like factor 11 (KLF11) that are essential for modulating the genomic program in white adipocytes to induce browning. Furthermore, we have shown that acute suppression of adipocyte genes by the proinflammatory cytokine, tumor necrosis factor (TNF), involves redistribution of cofactors to enhancers activated by the master inflammatory regulator, nuclear factor kappa-light-chain-enhancer of activated B cells (NF-κB). Interestingly, this redistribution occurs selectively from enhancers with high-cofactor occupancies, thereby predominantly affecting super-enhancers and their associated genes. We propose that this is a general mechanism contributing to transcriptional repression associated with activation of signal-dependent transcription factors.

Systems pharmacology of adiposity reveals inhibition of EP300 as a common therapeutic mechanism of caloric restriction and resveratrol for obesity

Both caloric restriction (CR) and resveratrol (RSV) have beneficial effects on obesity. However, the biochemical pathways that mediate these beneficial effects might be complex and interconnected and have not been fully elucidated. To reveal the common therapeutic mechanism of CR and RSV, we performed a comparative transcriptome analysis of adipose tissues from diet-induced obese (DIO) zebrafish and obese humans. We identified nine genes in DIO zebrafish and seven genes in obese humans whose expressions were regulated by CR and RSV. Although the gene lists did not overlap except for one gene, the gene ontologies enriched in the gene lists were highly overlapped, and included genes involved in adipocyte differentiation, lipid storage and lipid metabolism. Bioinformatic analysis of cis-regulatory sequences of these genes revealed that their transcriptional regulators also overlapped, including EP300, HDAC2, CEBPB, CEBPD, FOXA1, and FOXA2. We also identified 15 and 46 genes that were dysregulated in the adipose tissue of DIO zebrafish and obese humans, respectively. Bioinformatics analysis identified EP300, HDAC2, and CEBPB as common transcriptional regulators for these genes. EP300 is a histone and lysyl acetyltransferase that modulates the function of histone and various proteins including CEBPB, CEBPD, FOXA1, and FOXA2. We demonstrated that adiposity in larval zebrafish was significantly reduced by C646, an inhibitor of EP300 that antagonizes acetyl-CoA. The reduction of adiposity by C646 was not significantly different from that induced by RSV or co-treatment of C646 and RSV. These results indicate that the inhibition of EP300 might be a common therapeutic mechanism between CR and RSV in adipose tissues of obese individuals.

Association of abdominal obesity in children with perioperative respiratory adverse events

BACKGROUND/PURPOSE

Waist circumference (WC), a measure of abdominal obesity, is associated with several chronic disorders. Less is known about the association between WC and acute perioperative adverse events. The purpose of the present investigation was to test the hypothesis that abdominal obesity increases the occurrence of perioperative adverse events in children undergoing elective, noncardiac surgeries.

DESIGN

Prospective observational study.

METHODS

We studied the association between WC and perioperative adverse events in children aged 6 to 18 years who underwent elective noncardiac surgeries at our institution. Patients were considered to have abdominal obesity if WC was 90th percentile or greater for age and gender. Subsequently, univariate factors associated with abdominal obesity were explored and then odds ratios for the occurrence of perioperative respiratory adverse events were calculated from logistic regression after controlling for clinically pertinent covariates.

RESULTS

Among 1,102 patients, the prevalence of abdominal obesity was 23.1%. WC was positively correlated with age and measured anthropometric parameters. Composite perioperative adverse events were more frequent in children with abdominal obesity. After adjusting for several clinically relevant risk factors, abdominal obesity independently predicted increased relative odds of respiratory adverse events (OR = 2.35, 95% CI = 1.6 to 3.5, P < .001). Abdominal obesity was also associated with prolonged postanesthesia care unit (PACU) length of stay.

CONCLUSION

WC, a measure of abdominal obesity, is an independent predictor of perioperative respiratory adverse events in children undergoing elective noncardiac surgery. Furthermore, abdominal obesity was associated with prolonged PACU length of stay.

Genome-wide expression in visceral adipose tissue from obese prepubertal children

Characterization of the genes expressed in adipose tissue (AT) is key to understanding the pathogenesis of obesity and to developing treatments for this condition. Our objective was to compare the gene expression in visceral AT (VAT) between obese and normal-weight prepubertal children. A total of fifteen obese and sixteen normal-weight children undergoing abdominal elective surgery were selected. RNA was extracted from VAT biopsies. Microarray experiments were independently performed for each sample (six obese and five normal-weight samples). Validation by quantitative PCR (qPCR) was performed on an additional 10 obese and 10 normal-weight VAT samples. Of 1276 differentially expressed genes (p < 0.05), 245 were more than two-fold higher in obese children than in normal-weight children. As validated by qPCR, expression was upregulated in genes involved in lipid and amino acid metabolism (CES1, NPRR3 and BHMT2), oxidative stress and extracellular matrix regulation (TNMD and NQO1), adipogenesis (CRYAB and AFF1) and inflammation (ANXA1); by contrast, only CALCRL gene expression was confirmed to be downregulated. In conclusion, this study in prepubertal children demonstrates the up- and down-regulation of genes that encode molecules that were previously proposed to influence the pathogenesis of adulthood obesity, as well as previously unreported dysregulated genes that may be candidate genes in the aetiology of obesity.

VEGF in the crosstalk between human adipocytes and smooth muscle cells: depot-specific release from visceral and perivascular adipose tissue

Adipose tissue secrets adipokines and fatty acids, which may contribute to obesity-associated vascular dysfunction and cardiovascular risk. This study investigated which factors are responsible for the synergistic effect of adipokine and oleic acid- (OA-) induced proliferation of human vascular smooth muscle cells (VSMC). Adipocyte-conditioned medium (CM) from human adipocytes induces proliferation of VSMC in correlation to its vascular endothelial growth factor (VEGF) content. CM increases VEGF-receptor (VEGF-R) 1 and 2 expression and VEGF secretion of VSMC, while OA only stimulates VEGF secretion. VEGF neutralization abrogates CM- and OA-induced proliferation and considerably reduces proliferation induced by CM and OA in combination. VEGF release is higher from visceral adipose tissue (VAT) of obese subjects compared to subcutaneous adipose tissue (SAT) and VAT from lean controls. Furthermore, VEGF release from VAT correlates with its proliferative effect. Perivascular adipose tissue (PAT) from type 2 diabetic patients releases significantly higher amounts of VEGF and induces stronger proliferation of VSMC as compared to SAT and SAT/PAT of nondiabetics. In conclusion, VEGF is mediating CM-induced proliferation of VSMC. As this adipokine is released in high amounts from VAT of obese patients and PAT of diabetic patients, VEGF might link adipose tissue inflammation to increased VSMC proliferation.

Fat depot-specific mRNA expression of novel loci associated with waist-hip ratio

OBJECTIVE

We hypothesized that genes within recently identified loci associated with waist-hip ratio (WHR) exhibit fat depot-specific mRNA expression, which correlates with obesity-related traits.

METHODS

Adipose tissue (AT) mRNA expression of 6 genes (TBX15/WARS2, STAB1, PIGC, ZNRF3 and GRB14) within these loci showing coincident cis-expression quantitative trait loci was measured in 222 paired samples of human visceral (vis) and subcutaneous (sc) AT. The relationship of mRNA expression levels with obesity-related quantitative traits was assessed by Pearson's correlation analyses. Multivariate linear relationships were assessed by generalized linear regression models.

RESULTS

Whereas only PIGC, ZNFR3 and STAB1 mRNA expression in sc AT correlated nominally with WHR (P<0.05, adjusted for age and sex), mRNA expression of all studied genes in at least one of the fat depots correlated significantly with vis and/or sc fat area (P ranging from 0.05 to 4.0 × 10(6), adjusted for age and sex). Consistently, the transcript levels of WARS, PIGC and GRB14 were nominally associated with body mass index (BMI) (P ranging from 0.02 to 9.2 × 10(5), adjusted for age and sex). Moreover, independent of sex, obesity and diabetes status, differential expression between vis and sc AT was observed for all tested genes (P<0.01). Finally, the rs10195252 T-allele was nominally associated with increased GRB14 sc mRNA expression (P=0.025 after adjusting for age, sex and BMI).

CONCLUSIONS

Our data including the inter-depot variability of mRNA expression suggests that genes within the WHR-associated loci might be involved in the regulation of fat distribution.

Differences in gene expression and cytokine release profiles highlight the heterogeneity of distinct subsets of adipose tissue-derived stem cells in the subcutaneous and visceral adipose tissue in humans

Differences in the inherent properties of adipose tissue-derived stem cells (ASC) may contribute to the biological specificity of the subcutaneous (Sc) and visceral (V) adipose tissue depots. In this study, three distinct subpopulations of ASC, i.e. ASC_SVF, ASC_Bottom, and ASC_Ceiling, were isolated from Sc and V fat biopsies of non-obese subjects, and their gene expression and functional characteristics were investigated. Genome-wide mRNA expression profiles of ASC_SVF, ASC_Bottom and ASC_Ceiling from Sc fat were significantly different as compared to their homologous subsets of V-ASCs. Furthermore, ASC_SVF, ASC_Ceiling and ASC_Bottom from the same fat depot were also distinct from each other. In this respect, both principal component analysis and hierarchical clusters analysis showed that ASC_Ceiling and ASC_SVF shared a similar pattern of closely related genes, which was highly different when compared to that of ASC_Bottom. However, larger variations in gene expression were found in inter-depot than in intra-depot comparisons. The analysis of connectivity of genes differently expressed in each ASC subset demonstrated that, although there was some overlap, there was also a clear distinction between each Sc-ASC and their corresponding V-ASC subsets, and among ASC_SVF, ASC_Bottom, and ASC_Ceiling of Sc or V fat depots in regard to networks associated with regulation of cell cycle, cell organization and development, inflammation and metabolic responses. Finally, the release of several cytokines and growth factors in the ASC cultured medium also showed both inter- and intra-depot differences. Thus, ASC_Ceiling and ASC_Bottom can be identified as two genetically and functionally heterogeneous ASC populations in addition to the ASC_SVF, with ASC_Bottom showing the highest degree of unmatched gene expression. On the other hand, inter-depot seem to prevail over intra-depot differences in the ASC gene expression assets and network functions, contributing to the high degree of specificity of Sc and V adipose tissue in humans.

Visceral and subcutaneous adipose tissue from lean women respond differently to lipopolysaccharide-induced alteration of inflammation and glyceroneogenesis

OBJECTIVE

Experimental endotoxaemia induces subcutaneous adipose tissue inflammation and systemic insulin resistance in lean subjects. Glyceroneogenesis, by limiting free fatty acids (FFA) release from adipocytes, controls FFA homoeostasis and systemic insulin sensitivity. The roles of subcutaneous adipose tissue (SAT) and visceral adipose tissue (VAT) in metabolic deregulation are intrinsically different. We compared the effect of lipopolysaccharide (LPS) on the inflammation profiles of SAT and VAT explants from lean women, as well as on glyceroneogenesis, to test whether these two fat depots have intrinsically different responses to this metabolic endotoxin.

DESIGN

Abdominal SAT and VAT explants from eight lean women were treated in vitro with LPS. Their inflammatory status was evaluated by cytokine gene expression and secretion; glyceroneogenesis was evaluated by cytosolic phosphoenolpyruvate carboxykinase activity and FFA vs glycerol release.

RESULTS

In the basal state, the cytokine status and expression of macrophage markers were lower in SAT than VAT. In the presence of 100 ng ml(-1) LPS, SAT exhibited a strong inflammatory response (increased interleukin-6 and tumor necrosis factor-α expression) and increased release of FFA due to inhibition of glyceroneogenesis, whereas VAT was only mildly affected. The effects of LPS on both tissues were blocked by the nuclear factor-κB (NF-κB) inhibitor, parthenolide. A significant effect of LPS on VAT occurred only at 1 μg ml(-1) LPS.

CONCLUSION

SAT explants from lean women are more sensitive to LPS-induced NF-κB activation than are VAT explants, leading to a depot-specific dysfunction of FFA storage. As SAT is the major player in FFA homoeostasis, this SAT dysfunction could be associated with visceral fat hypertrophy and systemic lipid disorders.

An essential role for Tbx15 in the differentiation of brown and "brite" but not white adipocytes

The transcription factor Tbx15 is expressed predominantly in brown adipose tissue and in those white adipose depots that are capable of giving rise to brown-in-white ("brite"/"beige") adipocytes. Therefore, we have investigated a possible role here of Tbx15 in brown and brite adipocyte differentiation in vitro. Adipocyte precursors were isolated from interscapular and axilliary brown adipose tissues, inguinal white ("brite") adipose tissue, and epididymal white adipose tissue in 129/Sv mouse pups and differentiated in culture. Differentiation was enhanced by chronic treatment with the PPARγ agonist rosiglitazone plus the sympathetic neurotransmitter norepinephrine. Using short interfering RNAs (siRNA) directed toward Tbx15 in these primary adipocyte cultures, we decreased Tbx15 expression >90%. This resulted in reduced expression levels of adipogenesis markers (PPARγ, aP2). Importantly, Tbx15 knockdown reduced the expression of brown phenotypic marker genes (PRDM16, PGC-1α, Cox8b/Cox4, UCP1) in brown adipocytes and even more markedly in inguinal white adipocytes. In contrast, Tbx15 knockdown had no effect on white adipocytes originating from a depot that is not brite competent in vivo (epididymal). Therefore, Tbx15 may be essential for the development of the adipogenic and thermogenic programs in adipocytes/adipomyocytes capable of developing brown adipocyte features.