Effects of hypoxia on the expression of proangiogenic factors in differentiated 3T3-F442A adipocytes

The role of adipogenic niche resident cells in colorectal cancer progression in relation to obesity

Colorectal cancer (CRC) is the third most common cancer worldwide and has one of the highest mortality rates. Considering its nonlinear etiology, many risk factors are associated with CRC formation and development, with obesity at the forefront. Obesity is regarded as one of the key environmental risk determinants for the pathogenesis of CRC. Excessive food intake and a sedentary lifestyle, together with genetic predispositions, lead to the overgrowth of adipose tissue along with a disruption in the number and function of its building cells. Adipose tissue-resident cells may constitute part of the CRC microenvironment. Alterations in their physiology and secretory profiles observed in obesity may further contribute to CRC progression, and despite similar localization, their contributions are not equivalent. They can interact with CRC cells, either directly or indirectly, influencing various processes that contribute to tumorigenesis. The main aim of this review is to provide insights into the diversity of adipose tissue resident cells, namely, adipocytes, adipose stromal cells, and immunological cells, regarding the role of particular cell types in co-forming the CRC microenvironment. The scope of this study was also devoted to the abnormalities in adipose tissue physiology observed in obesity states and their impact on CRC development.

Hypoxia signaling in the adipose tissue

Obesity per se is rapidly emerging all over the planet and further accounts for many other life-threatening conditions, such as diabetes, cardiovascular diseases, and cancers. Decreased oxygen supply or increased relative oxygen consumption in the adipose tissue results in adipose tissue hypoxia, which is a hallmark of obesity. This review aims to provide an up-to-date overview of the hypoxia signaling in the adipose tissue. First, we summarize literature evidence to demonstrate that hypoxia is regularly observed during adipose tissue remodeling in humans and rodent models with obesity. Next, we discuss how hypoxia-inducible factors (HIFs) are regulated and how adipose tissues behave in response to hypoxia. Then, the differential roles of adipose HIF-1α and HIF-2α in adipose tissue biology and obesity pathology are highlighted. Finally, the review emphasizes the importance of modulating adipose hypoxia as a therapeutic avenue to assist adipose tissues in functionally adapting to hypoxic conditions, ultimately promoting adipose health and improving outcomes due to obesity.

NPTX1 Mediates the Facilitating Effects of Hypoxia-Stimulated Human Adipocytes on Adipose-Derived Stem Cell Activation and Autologous Adipose Graft Survival Rate

BACKGROUND

Autologous adipose tissue is an ideal material for soft tissue filling and transplantation; however, high volumes of fat absorption over time lead to a relatively low overall survival percentage. The survival and differentiation of adipose-derived stem cells (ADSCs) in the transplanted microenvironment might improve adipose graft survival. Adipocytes have been reported to affect ADSC activation. However, its underlying mechanisms remain unclear.

METHODS

Human ADSCs were incubated in a culture medium supplemented with hypoxic or normoxic conditioned culture medium (CM) derived from human adipocytes. Neuronal Pentraxin 1 (NPTX1) was overexpressed or knocked down in human adipocytes using an overexpression vector (NPTX1 OE) or small interfering RNA (siRNA) transfection, respectively. ADSC differentiation and paracrine secretion were assessed. Nude mice were implanted with human adipocytes and ADSCs. The adipose tissue was subsequently evaluated by histological analysis.

RESULTS

CM from hypoxic-stimulated human adipocytes significantly facilitated the differentiation ability and paracrine levels of ADSCs. NPTX1 was significantly up-regulated in human adipocytes exposed to hypoxic conditions. In vitro, CM derived from hypoxia-stimulated human adipocytes or NPTX1-overexpressing human adipocytes exposed to normoxia promoted ADSC differentiation and paracrine; after silencing NPTX1, the facilitating effects of hypoxia-treated human adipocytes on ADSC activation were eliminated. Similarly, in vivo, the NPTX1 OE + normoxia-CM group saw improved histological morphology and fat integrity, less fibrosis and inflammation, and increased vessel numbers compared with the OE NC + normoxia-CM group; the adipocyte grafts of the si-NC + hypoxia-CM group yielded the most improved histological morphology, fat integrity, and the most vessel numbers. However, these enhancements of ADSC activation and adipose graft survival were partially abolished by NPTX1 knockdown in human adipocytes.

CONCLUSION

NPTX1 might mediate the facilitating effects of hypoxia-stimulated human adipocytes on ADSC activation, thereby improving adipose tissue survival rate after autologous fat transplantation and the effectiveness of autologous fat transplantation through promoting ADSC activation.

LEVEL OF EVIDENCE III

This journal requires that authors assign a level of evidence to each article. For a full description of these Evidence-Based Medicine ratings, please refer to the Table of Contents or the online Instructions to Authors www.springer.com/00266 .

Remodeling of white adipose tissue microenvironment against obesity by phytochemicals

Obesity is a kind of chronic disease due to a long-term imbalance between energy intake and expenditure. In recent years, the number of obese people around the world has soared, and obesity problem should not be underestimated. Obesity is characterized by changes in the adipose microenvironment, mainly manifested as hypertrophy, chronic inflammatory status, hypoxia, and fibrosis, thus contributing to the pathological changes of other tissues. A plethora of phytochemicals have been found to improve adipose microenvironment, thus prevent and resist obesity, providing a new research direction for the treatment of obesity and related diseases. This paper discusses remodeling of the adipose tissue microenvironment as a therapeutic avenue and reviews the progress of phytochemicals in fighting obesity by improving the adipose microenvironment.

Therapeutic Targeting of Hypoxia-Inducible Factors in Cancer

In the realm of cancer therapeutics, targeting the hypoxia-inducible factor (HIF) pathway has emerged as a promising strategy. This study delves into the intricate web of HIF-associated mechanisms, exploring avenues for future anticancer therapies. Framing the investigation within the broader context of cancer progression and hypoxia response, this article aims to decipher the pivotal role played by HIF in regulating genes influencing angiogenesis, cell proliferation, and glucose metabolism. Employing diverse approaches such as HIF inhibitors, anti-angiogenic therapies, and hypoxia-activated prodrugs, the research methodologically intervenes at different nodes of the HIF pathway. Findings showcase the efficacy of agents like EZN-2968, Minnelide, and Acriflavine in modulating HIF-1α protein synthesis and destabilizing HIF-1, providing preliminary proof of HIF-1α mRNA modulation and antitumor activity. However, challenges, including toxicity, necessitate continued exploration and development, as exemplified by ongoing clinical trials. This article concludes by emphasizing the potential of targeted HIF therapies in disrupting cancer-related signaling pathways.

Adipocyte Glucocorticoid Receptor Activation With High Glucocorticoid Doses Impairs Healthy Adipose Tissue Expansion by Repressing Angiogenesis

In humans, glucocorticoids (GCs) are commonly prescribed because of their anti-inflammatory and immunosuppressive properties. However, high doses of GCs often lead to side effects, including diabetes and lipodystrophy. We recently reported that adipocyte glucocorticoid receptor (GR)-deficient (AdipoGR-KO) mice under corticosterone (CORT) treatment exhibited a massive adipose tissue (AT) expansion associated with a paradoxical improvement of metabolic health compared with control mice. However, whether GR may control adipose development remains unclear. Here, we show a specific induction of hypoxia-inducible factor 1α (HIF-1α) and proangiogenic vascular endothelial growth factor A (VEGFA) expression in GR-deficient adipocytes of AdipoGR-KO mice compared with control mice, together with an increased adipose vascular network, as assessed by three-dimensional imaging. GR activation reduced HIF-1α recruitment to the Vegfa promoter resulting from Hif-1α downregulation at the transcriptional and posttranslational levels. Importantly, in CORT-treated AdipoGR-KO mice, the blockade of VEGFA by a soluble decoy receptor prevented AT expansion and the healthy metabolic phenotype. Finally, in subcutaneous AT from patients with Cushing syndrome, higher VEGFA expression was associated with a better metabolic profile. Collectively, these results highlight that adipocyte GR negatively controls AT expansion and metabolic health through the downregulation of the major angiogenic effector VEGFA and inhibition of vascular network development.

ARTICLE HIGHLIGHTS

Adipose Tissue Hypoxia in Obesity: Clinical Reappraisal of Hypoxia Hypothesis

Obese subjects exhibit lower adipose tissue oxygen consumption in accordance with the lower adipose tissue blood flow. Thereby, compared to lean subjects, obese individuals have almost half lower capillary density and more than half lower vascular endothelial growth factor (VEGF). The VEGF expression together with hypoxia-inducible transcription factor-1 alpha (HIF-1α) activity also requires phosphatidylinositol 3-kinase (PI3K) and mammalian target of rapamycin (mTOR)-mediated signaling. Especially HIF-1α is an important signaling molecule for hypoxia to induce the inflammatory responses. Hypoxia contributes to several biological functions, such as angiogenesis, cell proliferation, apoptosis, inflammation, and insulin resistance (IR). Pathogenesis of obesity-related comorbidities is attributed to intermittent hypoxia (IH), which is mostly observed in visceral obesity. Proinflammatory phenotype of the adipose tissue is a crucial link between IH and the development of IR. Inhibition of adaptive unfolded protein response (UPR) in hypoxia increases β cell death. Moreover, deletion of HIF-1α worsens β cell function. Oxidative stress, as well as the release of proinflammatory cytokines/adipokines in obesity, is proportional to the severity of IH. Reactive oxygen species (ROS) generation at mitochondria is responsible for propagation of the hypoxic signal; however, mitochondrial ROS production is required for hypoxic HIF-1α protein stabilization. Alterations in oxygen availability of adipose tissue directly affect the macrophage polarization and are responsible for the dysregulated adipocytokines production in obesity. Hypoxia both inhibits adipocyte differentiation from preadipocytes and macrophage migration from the hypoxic adipose tissue. Upon reaching a hypertrophic threshold beyond the adipocyte fat loading capacity, excess extracellular matrix (ECM) components are deposited, causing fibrosis. HIF-1α initiates the whole pathological process of fibrosis and inflammation in the obese adipose tissue. In addition to stressed adipocytes, hypoxia contributes to immune cell migration and activation which further aggravates adipose tissue fibrosis. Therefore, targeting HIF-1α might be an efficient way to suppress hypoxia-induced pathological changes in the ECM. The fibrosis score of adipose tissue correlates negatively with the body mass index and metabolic parameters. Inducers of browning/beiging adipocytes and adipokines, as well as modulations of matrix remodeling enzyme inhibitors, and associated gene regulators, are potential pharmacological targets for treating obesity.

Next-Cell Hypothesis: Mechanism of Obesity-Associated Carcinogenesis

Higher body fat content is related to a higher risk of mortality, and obesity-related cancer represents approximately 40% of all cancer patients diagnosed each year. Furthermore, epigenetic mechanisms are involved in cellular metabolic memory and can determine one's predisposition to being overweight. Low-grade chronic inflammation, a well-established characteristic of obesity, is a central component of tumor development and progression. Cancer-associated adipocytes (CAA), which enhance inflammation- and metastasis-related gene sets within the cancer microenvironment, have pro-tumoral effects. Adipose tissue is a major source of the exosomal micro ribonucleic acids (miRNAs), which modulate pathways involved in the development of obesity and obesity-related comorbidities. Owing to their composition of cargo, exosomes can activate receptors at the target cell or transfer molecules to the target cells and thereby change the phenotype of these cells. Exosomes that are released into the extracellular environment are internalized with their cargo by neighboring cells. The tumor-secreted exosomes promote organ-specific metastasis of tumor cells that normally lack the capacity to metastasize to a specific organ. Therefore, the communication between neighboring cells via exosomes is defined as the "next-cell hypothesis." The reciprocal interaction between the adipocyte and tumor cell is realized through the adipocyte-derived exosomal miRNAs and tumor cell-derived oncogenic miRNAs. The cargo molecules of adipocyte-derived exosomes are important messengers for intercellular communication involved in metabolic responses and have very specific signatures that direct the metabolic activity of target cells. RNA-induced silencing regulates gene expression through various mechanisms. Destabilization of DICER enzyme, which catalyzes the conversion of primary miRNA (pri-miRNA) to precursor miRNA (pre-miRNA), is an important checkpoint in cancer development and progression. Interestingly, adipose tissue in obesity and tumors share similar pathogenic features, and the local hypoxia progress in both. While hypoxia in obesity leads to the adipocyte dysfunction and metabolic abnormalities, in obesity-related cancer cases, it is associated with worsened prognosis, increased metastatic potential, and resistance to chemotherapy. Notch-interleukin-1 (IL-1)-Leptin crosstalk outcome is referred to as "NILCO effect." In this chapter, obesity-related cancer development is discussed in the context of "next-cell hypothesis," miRNA biogenesis, and "NILCO effect."

Endoplasmic Reticulum Stress Promotes the Expression of TNF-α in THP-1 Cells by Mechanisms Involving ROS/CHOP/HIF-1α and MAPK/NF-κB Pathways

Obesity and metabolic syndrome involve chronic low-grade inflammation called metabolic inflammation as well as metabolic derangements from increased endotoxin and free fatty acids. It is debated whether the endoplasmic reticulum (ER) stress in monocytic cells can contribute to amplify metabolic inflammation; if so, by which mechanism(s). To test this, metabolic stress was induced in THP-1 cells and primary human monocytes by treatments with lipopolysaccharide (LPS), palmitic acid (PA), or oleic acid (OA), in the presence or absence of the ER stressor thapsigargin (TG). Gene expression of tumor necrosis factor (TNF)-α and markers of ER/oxidative stress were determined by qRT-PCR, TNF-α protein by ELISA, reactive oxygen species (ROS) by DCFH-DA assay, hypoxia-inducible factor 1-alpha (HIF-1α), p38, extracellular signal-regulated kinase (ERK)-1,2, and nuclear factor kappa B (NF-κB) phosphorylation by immunoblotting, and insulin sensitivity by glucose-uptake assay. Regarding clinical analyses, adipose TNF-α was assessed using qRT-PCR/IHC and plasma TNF-α, high-sensitivity C-reactive protein (hs-CRP), malondialdehyde (MDA), and oxidized low-density lipoprotein (OX-LDL) via ELISA. We found that the cooperative interaction between metabolic and ER stresses promoted TNF-α, ROS, CCAAT-enhancer-binding protein homologous protein (CHOP), activating transcription factor 6 (ATF6), superoxide dismutase 2 (SOD2), and nuclear factor erythroid 2-related factor 2 (NRF2) expression (p ≤ 0.0183),. However, glucose uptake was not impaired. TNF-α amplification was dependent on HIF-1α stabilization and p38 MAPK/p65 NF-κB phosphorylation, while the MAPK/NF-κB pathway inhibitors and antioxidants/ROS scavengers such as curcumin, allopurinol, and apocynin attenuated the TNF-α production (p ≤ 0.05). Individuals with obesity displayed increased adipose TNF-α gene/protein expression as well as elevated plasma levels of TNF-α, CRP, MDA, and OX-LDL (p ≤ 0.05). Our findings support a metabolic-ER stress cooperativity model, favoring inflammation by triggering TNF-α production via the ROS/CHOP/HIF-1α and MAPK/NF-κB dependent mechanisms. This study also highlights the therapeutic potential of antioxidants in inflammatory conditions involving metabolic/ER stresses.

A glimpse of the connection between PPARγ and macrophage

Nuclear receptors are ligand-regulated transcription factors that regulate vast cellular activities and serve as an important class of drug targets. Among them, peroxisome proliferator-activated receptors (PPARs) are members of the nuclear receptor family and have been extensively studied for their roles in metabolism, differentiation, development, and cancer, among others. Recently, there has been considerable interest in understanding and defining the function of PPARs and their agonists in regulating innate and adaptive immune responses and their pharmacological potential in combating chronic inflammatory diseases. In this review, we focus on emerging evidence for the potential role of PPARγ in macrophage biology, which is the prior innate immune executive in metabolic and tissue homeostasis. We also discuss the role of PPARγ as a regulator of macrophage function in inflammatory diseases. Lastly, we discuss the possible application of PPARγ antagonists in metabolic pathologies.

Obesity Is Associated with Immunometabolic Changes in Adipose Tissue That May Drive Treatment Resistance in Breast Cancer: Immune-Metabolic Reprogramming and Novel Therapeutic Strategies

White adipose tissue (WAT) represents an endocrinologically and immunologically active tissue whose primary role is energy storage and homeostasis. Breast WAT is involved in the secretion of hormones and proinflammatory molecules that are associated with breast cancer development and progression. The role of adiposity and systemic inflammation in immune responses and resistance to anti-cancer treatment in breast cancer (BC) patients is still not clear. Metformin has demonstrated antitumorigenic properties both in pre-clinical and clinical studies. Nevertheless, its immunomodulating properties in BC are largely unknown. This review aims to evaluate the emerging evidence on the crosstalk between adiposity and the immune-tumour microenvironment in BC, its progression and treatment resistance, and the immunometabolic role of metformin in BC. Adiposity, and by extension subclinical inflammation, are associated with metabolic dysfunction and changes in the immune-tumour microenvironment in BC. In oestrogen receptor positive (ER+) breast tumours, it is proposed that these changes are mediated via a paracrine interaction between macrophages and preadipocytes, leading to elevated aromatase expression and secretion of pro-inflammatory cytokines and adipokines in the breast tissue in patients who are obese or overweight. In HER2+ breast tumours, WAT inflammation has been shown to be associated with resistance to trastuzumab mediated via MAPK or PI3K pathways. Furthermore, adipose tissue in patients with obesity is associated with upregulation of immune checkpoints on T-cells that is partially mediated via immunomodulatory effects of leptin and has been paradoxically associated with improved responses to immunotherapy in several cancers. Metformin may play a role in the metabolic reprogramming of tumour-infiltrating immune cells that are dysregulated by systemic inflammation. In conclusion, evidence suggests that body composition and metabolic status are associated with patient outcomes. To optimise patient stratification and personalisation of treatment, prospective studies are required to evaluate the role of body composition and metabolic parameters in metabolic immune reprogramming with and without immunotherapy in patients with BC.

Associations of body mass index and weight change with circulating levels of high-sensitivity C-reactive protein, proinflammatory cytokines, and adiponectin among breast cancer survivors

AIM

This study examined the associations of body mass index (BMI) and weight change with inflammatory markers among breast cancer survivors in Korea.

METHODS

A total of 495 women were included who had been diagnosed with primary breast cancer and survived for at least 6 months since the surgery. Information on the body weight and height of the participants was collected both at the study enrollment and diagnosis. The plasma levels of inflammatory markers were measured, including high-sensitivity C-reactive protein, interleukin (IL)-6, IL-8, tumor necrosis factor-α, and adiponectin. A summary z-score was calculated by summing up the z-scores of each biomarker. The least-square means and 95% confidence intervals (CIs) were calculated using a generalized linear model and odds ratios (ORs) and 95% CIs for the elevated levels of inflammatory markers with a multivariate logistic regression model.

RESULTS

Participants with a BMI ≥27.5 kg/m² at the study enrollment and at diagnosis were significantly associated with elevated summary z-scores compared to those with a BMI < 23 kg/m² ; the ORs (95% CIs) were 5.42 (2.15-13.71) for current BMI and 3.66 (1.68-7.98) for BMI at diagnosis, respectively. Additionally, a weight loss > 5% since diagnosis was associated with a lower prevalence of high summary z-scores; the OR (95% CI) was .20 (.08-.52) compared to a stable weight.

CONCLUSIONS

A high BMI at diagnosis and current BMI with a greater degree were associated with unfavorable levels of inflammatory markers among breast cancer survivors. Additionally, weight loss since diagnosis was inversely associated with these markers.

Identification and analysis of hub genes of hypoxia-immunity in type 2 diabetes mellitus

The chronic metabolic disease named type 2 diabetes (T2D) accounts for over 90% of diabetes mellitus. An increasing number of evidences have revealed that hypoxia has a significantly suppressive effect on cell-mediated immunity, as well as the utilization of glucose in diabetics. Therefore, we aimed to screen and identify hypoxia-immune-related hub genes in T2D through bioinformatic analysis. The Gene Expression Omnibus (GEO) database was used to get T2D gene expression profile data in the peripheral blood samples (GSE184050), and hypoxia-related genes were acquired from Molecular Signatures Database (MSigDB). Differentially expressed mRNAs (DEGs) and lncRNAs (DELs) between T2D and normal samples were identified by DeSeq2 package. The clusterProfiler package was used to perform enrichment analyses for the overlapped genes of DEGs and hypoxia-related genes. Further, Hypoxia-related hub genes were discovered using two machine learning algorithms. Next, the compositional patterns of immune and stromal cells in T2D and healthy groups were estimated by using xCell algorithm. Moreover, we used the weighted correlation network analysis (WGCNA) to examine the connection between genes and immune cells to screen immune-related genes. Gene Set Enrichment Analysis (GSEA) was used to investigate the functions of the hypoxia-immune-related hub genes. Finally, two peripheral blood cohorts of T2D (GSE184050 and GSE95849) as well as the quantitative real-time PCR (qRT-PCR) experiments for clicinal peripheral blood samples with T2D were used for verification analyses of hub genes. And meanwhile, a lncRNA-TF-mRNA network was constructed. Following the differentially expressed analysis, 38 out of 3822 DEGs were screened as hypoxia-related DEGs, and 493 DELs were found. These hypoxia-related DEGs were mainly enriched in the GO terms of pyruvate metabolic process, cytoplasmic vesicle lumen and monosaccharide binding, and the KEGG pathways of glycolysis/gluconeogenesis, pentose phosphate pathway and biosynthesis of nucleotide sugars. Moreover, 7 out of hypoxia-related DEGs were identified as hub genes. There were six differentially expressed immune cell types between T2D and healthy samples, which were further used as the clinical traits for WGCNA to identify AMPD3 and IER3 as the hypoxia-immune-related hub genes. The results of the KEGG pathways of genes in high-expression groups of AMPD3 and IER3 were mainly concentrated in glycosaminoglycan degradation and vasopressin-regulated water reabsorption, while the low-expression groups of AMPD3 and IER3 were mainly associated with RNA degradation and nucleotide excision repair. Finally, when compared to normal samples, both the AMPD3 and IER3 were highly expressed in the T2D groups in the GSE184050 and GSE95849 datasets. The result of lncRNA-TF-mRNA regulatory network showed that lncRNAs such as BACH1-IT1 and SNHG15 might induce the expression of the corresponding TFs such as TFAM and THAP12 and upregulate the expression of AMPD3. This study identified AMPD3 and IER3 as hypoxia-immune-related hub genes and potential regulatory mechanism for T2D, which provided a new perspective for elucidating the upstream molecular regulatory mechanism of diabetes mellitus.

Hypoxia-Inducible Factor-1: A Novel Therapeutic Target for the Management of Cancer, Drug Resistance, and Cancer-Related Pain

Hypoxia-inducible factor-1 (HIF-1) is a key transcription factor that regulates the transcription of many genes that are responsible for the adaptation and survival of tumor cells in hypoxic environments. Over the past few decades, tremendous efforts have been made to comprehensively understand the role of HIF-1 in tumor progression. Based on the pivotal roles of HIF-1 in tumor biology, many HIF-1 inhibitors interrupting expression, stabilization, DNA binding properties, or transcriptional activity have been identified as potential therapeutic agents for various cancers, yet none of these inhibitors have yet been successfully translated into clinically available cancer treatments. In this review, we briefly introduce the regulation of the HIF-1 pathway and summarize its roles in tumor cell proliferation, angiogenesis, and metastasis. In addition, we explore the implications of HIF-1 in the development of drug resistance and cancer-related pain: the most commonly encountered obstacles during conventional anticancer therapies. Finally, the current status of HIF-1 inhibitors in clinical trials and their perspectives are highlighted, along with their modes of action. This review provides new insights into novel anticancer drug development targeting HIF-1. HIF-1 inhibitors may be promising combinational therapeutic interventions to improve the efficacy of current cancer treatments and reduce drug resistance and cancer-related pain.

Role of Circadian Transcription Factor Rev-Erb in Metabolism and Tissue Fibrosis

Circadian rhythms significantly affect metabolism, and their disruption leads to cardiometabolic diseases and fibrosis. The clock repressor Rev-Erb is mainly expressed in the liver, heart, lung, adipose tissue, skeletal muscles, and brain, recognized as a master regulator of metabolism, mitochondrial biogenesis, inflammatory response, and fibrosis. Fibrosis is the response of the body to injuries and chronic inflammation with the accumulation of extracellular matrix in tissues. Activation of myofibroblasts is a key factor in the development of organ fibrosis, initiated by hormones, growth factors, inflammatory cytokines, and mechanical stress. This review summarizes the importance of Rev-Erb in ECM remodeling and tissue fibrosis. In the heart, Rev-Erb activation has been shown to alleviate hypertrophy and increase exercise capacity. In the lung, Rev-Erb agonist reduced pulmonary fibrosis by suppressing fibroblast differentiation. In the liver, Rev-Erb inhibited inflammation and fibrosis by diminishing NF-κB activity. In adipose tissue, Rev- Erb agonists reduced fat mass. In summary, the results of multiple studies in preclinical models demonstrate that Rev-Erb is an attractive target for positively influencing dysregulated metabolism, inflammation, and fibrosis, but more specific tools and studies would be needed to increase the information base for the therapeutic potential of these substances interfering with the molecular clock.

Intra-abdominal adipose depot variation in adipogenesis, lipogenesis, angiogenesis, and fibrosis gene expression and relationships with insulin resistance and inflammation in premenopausal women with severe obesity

Although severe obesity is associated with insulin resistance (IR) and inflammation, secretory function of intra-abdominal adipose tissues and their relationships with IR and inflammation markers remain poorly understood. Aims were to measure gene expression of adipogenic (C/EBPα/β, PPARγ-1/2, SREBP-1c, LXRα), lipogenic (SCD1, DGAT-1/2), angiogenic (VEGFα, leptin), and fibrotic (LOX, COL6A3) factors in the round ligament (RL), omental (OM), and mesenteric (ME) fat depots and to evaluate their relationships with IR and inflammation markers in 48 women with severe obesity undergoing bariatric surgery. Gene expression was assessed by RT-qPCR, and plasma glucose and insulin (HOMA-IR calculated), PAI-1, IL-6, TNFα, adiponectin, and leptin levels were determined. C/EBPβ and PPARγ-1/2 mRNA levels were more expressed in the OM (0.001<p<0.05). ME showed the highest expression of C/EBPα, SREBP-1c, DGAT-2, and leptin and the lowest of SCD1, LXRα, VEGFα, and LOX (0.001<p<0.05). COL6A3 expression was higher in the ME and RL (p<0.001). COL6A3 expression was negatively associated with IR indices in the RL (0.01<p<0.05) and with fasting glycemia and HOMA-IR in the OM (0.001<p<0.05). VEGFα expression was positively related to TNFα and PAI-1 in the RL (0.001<p<0.05) and to PAI-1 in the OM (p<0.05) and negatively to PAI-1 in the ME (p<0.001). Fibrosis gene expression correlated negatively with inflammation in RL and OM (0.001<p<0.05) and positively with PAI-1 in the ME (0.001<p<0.05). The varying relationships of gene expression profiles with selected IR indices and inflammation biomarkers further suggest these fat depots have distinct contributions to overall health in premenopausal women with severe obesity.

Ovariectomy Causes Degeneration of Perivascular Adipose Tissue

Women are more resistant than men to the development of vascular diseases. However, menopause is a factor leading to deterioration of female vascular integrity, and it is reported that the risk of vascular diseases such as atherosclerosis and abdominal aortic aneurysm is increased in postmenopausal women. Although it is suggested that perivascular adipose tissue (PVAT) is deeply involved in the increased risk of vascular disease development, the effect of menopause on PVAT integrity is unknown. In this study, we aimed to elucidate the effect of menopause on PVAT in ovariectomized (OVX) rats. PVAT was divided into 4 regions based on characteristics. Hypertrophy and increased inflammation of adipocytes in the PVAT were observed in the OVX group, but the effects of OVX were different for each region. OVX induced matrix metalloproteinase (MMP) -9 which degrade extracellular matrix such as elastin and collagen fibers in PVAT. Degeneration of the arterial fibers of the thoracic and abdominal aorta were observed in the OVX group. These results indicate that OVX can cause dysfunction of PVAT which can cause degradation of arterial fibers. Appropriate management of PVAT may play an important role in the prevention and treatment of diseases originating from ovarian hypofunction.

Differentially expressed miRNAs in bone after methotrexate treatment

Previous studies have shown that administration of antimetabolite methotrexate (MTX) caused a reduced trabecular bone volume and increased marrow adiposity (bone/fat switch), for which the underlying molecular mechanisms and recovery potential are unclear. Altered expression of microRNAs (miRNAs) has been shown to be associated with dysregulation of osteogenic and/or adipogenic differentiation by disrupting target gene expression. First, the current study confirmed the bone/fat switch following MTX treatment in precursor cell culture models in vitro. Then, using a rat intensive 5-once daily MTX treatment model, this study aimed to identify miRNAs associated with bone damage and recovery (in a time course over Days 3, 6, 9, and 14 after the first MTX treatment). RNA isolated from bone samples of treated and control rats were subjected to miRNA array and reverse transcription-polymerase chain reaction validation, which identified five upregulated miRNA candidates, namely, miR-155-5p, miR-154-5p, miR-344g, miR-6215, and miR-6315. Target genes of these miRNAs were predicted using TargetScan and miRDB. Then, the protein-protein network was established via STRING database, after which the miRNA-key messenger RNA (mRNA) network was constructed by Cytoscape. Functional annotation and pathway enrichment analyses for miR-6315 were performed by DAVID database. We found that TGF-β signaling was the most significantly enriched pathway and subsequent dual-luciferase assays suggested that Smad2 was the direct target of miR-6315. Our current study showed that miR-6315 might be a vital regulator involved in bone and marrow fat formation. Also, this study constructed a comprehensive miRNA-mRNA regulatory network, which may contribute to the pathogenesis/prognosis of MTX-associated bone loss and bone marrow adiposity.

Inhibition of PDGF-BB reduces alkali-induced corneal neovascularization in mice

The aim of the present study was to investigate the role of platelet-derived growth factor (PDGF)-BB/PDGF receptor (R)-β signaling in an experimental murine corneal neovascularization (CrNV) model. Experimental CrNV was induced by alkali injury. The intra-corneal expression of PDGF-BB was examined using immunohistochemistry. The effect of PDGF-BB on CrNV was evaluated using immunofluorescence staining. The expression levels of PDGFR-β in human retinal endothelial cells (HRECs) under normal conditions or following cobalt chloride treatment, which induced hypoxic conditions, was assessed using reverse transcription-quantitative PCR. The effect of exogenous treatment of PDGF-BB on the proliferation, migration and tube formation of HRECs under normoxic or hypoxic conditions was evaluated in vitro using Cell Counting Kit-8, wound healing and 3D Matrigel capillary tube formation assays, respectively. The results indicated that the intra-corneal expression levels of the proteins of PDGF-BB and PDGFR-β were detectable on days 2 and 7 following alkali injury. The treatment with neutralizing anti-PDGF-BB antibody resulted in significant inhibition of CrNV. The intra-corneal expression levels of vascular endothelial growth factor A, matrix metallopeptidase (MMP)-2 and MMP-9 proteins were downregulated, while the expression levels of thrombospondin (TSP)-1, TSP-2, a disintegrin and metalloproteinase with thrombospondin motifs (ADAMTS)-1 and ADAMTS-2 were upregulated significantly in mice treated with anti-PDGF-BB antibody. The expression levels of PDGFR-β were upregulated in HRECs under hypoxic conditions compared with those noted under normoxic conditions. Recombinant human PDGF-BB promoted the proliferation, migration and tube formation of HRECs under hypoxic conditions. The data indicated that PDGF-BB/PDGFR-β signaling was involved in CrNV and that it promoted endothelial cell proliferation, migration and tube formation. The pro-angiogenic effects of this pathway may be mediated via the induction of pro-angiogenic cytokine secretion and the suppression of anti-angiogenic cytokine secretion.

Effects of interleukin-6 and tumor necrosis factor-α on the expression of angiogenic and collagenolytic factors in premature and mature adipocytes

OBJECTIVE

The remodeling of the vascular network and collagen in the extracellular matrix is closely associated with the expansion and dysfunction of adipose tissue. In the present study, we investigated the effects of interleukin (IL)-6 and tumor necrosis factor (TNF)-α on the expression of angiogenic factors, collagen, and collagenase and its endogenous inhibitor in premature and mature adipocytes.

METHODS

Premature and mature adipocytes were differentiated from 3T3-L1 cells and stimulated with IL-6 or TNF-α to mimic the early and late phases of obesity development. The levels of expression of angiogenic factors, including vascular endothelial cell growth factor a (Vegfa), hepatocyte growth factor (Hgf), angiopoietin (Angpt)1, and Angpt2, as well as type I collagen, matrix metallopeptidase (Mmp) 13, and tissue inhibitor of Mmp (Timp) 1, were determined using real-time reverse transcription polymerase chain reaction or enzyme-linked immunosorbent assay. Human umbilical vein endothelial cells were grown with the culture supernatant of adipocytes stimulated with/without IL-6 or TNF-α, and the formation of tube structures was evaluated.

RESULTS

IL-6 and TNF-α induced the expression of Vegfa, Hgf, and Angpt2 and decreased the expression of Angpt1 in premature adipocytes, whereas, they decreased the expression of Vegfa and Hgf in mature adipocytes. The culture supernatant of IL-6- or TNF-α-stimulated premature adipocytes induced the formation of tube structures. IL-6 and TNF-α had no effects on type I collagen expression in both premature and mature adipocytes but suppressed the expression of Mmp13 and Timp1 in mature and premature adipocytes, respectively.

CONCLUSION

The effects of IL-6 and TNF-α on the expression of angiogenic and collagenolytic factors differed between premature and mature adipocytes. This finding suggests that these inflammatory cytokines induce expansion and dysfunction of adipose tissue via angiogenesis and collagen turnover in premature and mature adipocytes.

Oxygenated Water Inhibits Adipogenesis and Attenuates Hepatic Steatosis in High-Fat Diet-Induced Obese Mice

The expansion of adipose tissue mass is the primary characteristic of the process of becoming obesity, which causes chronic adipose inflammation and is closely associated with type 2 diabetes mellitus (T2DM). Adipocyte hypertrophy restricts oxygen availability, leading to microenvironmental hypoxia and adipose dysfunction. This study aimed at investigating the effects of oxygenated water (OW) on adipocyte differentiation (adipogenesis) and the metabolic function of mature adipocytes. The effects of OW on adipogenesis and the metabolic function of mature adipocytes were examined. Meanwhile, the in vivo metabolic effects of long-term OW consumption on diet-induced obesity (DIO) mice were investigated. OW inhibited adipogenesis and lipid accumulation through down-regulating critical adipogenic transcription factors and lipogenic enzymes. While body weight, blood and adipose parameters were not significantly improved by long-term OW consumption, transient circulatory triglyceride-lowering and glucose tolerance-improving effects were identified. Notably, hepatic lipid contents were significantly reduced, indicating that the DIO-induced hepatic steatosis was attenuated, despite no improvements in fibrosis and lipid contents in adipose tissue being observed in the OW-drinking DIO mice. The study provides evidence regarding OW’s effects on adipogenesis and mature adipocytes, and the corresponding molecular mechanisms. OW exhibits transient triglyceride-lowering and glucose tolerance-improving activity as well as hepatic steatosis-attenuating functions.

Apple Flavonols Mitigate Adipocyte Inflammation and Promote Angiogenic Factors in LPS- and Cobalt Chloride-Stimulated Adipocytes, in Part by a Peroxisome Proliferator-Activated Receptor-γ-Dependent Mechanism

Adipose tissue (AT) expansion induces local hypoxia, a key contributor to the chronic low-grade inflammation that drives obesity-associated disease. Apple flavonols phloretin (PT) and phlorizin (PZ) are suggested anti-inflammatory molecules but their effectiveness in obese AT is inadequately understood. Using in vitro models designed to reproduce the obese AT microenvironment, 3T3-L1 adipocytes were cultured for 24 h with PT or PZ (100 μM) concurrent with the inflammatory stimulus lipopolysaccharide (LPS; 10 ng/mL) and/or the hypoxia mimetic cobalt chloride (CoCl₂; 100 μM). Within each condition, PT was more potent than PZ and its effects were partially mediated by peroxisome proliferator-activated receptor (PPAR)-γ (p < 0.05), as tested using the PPAR-γ antagonist bisphenol A diglycidyl ether (BADGE). In LPS-, CoCl₂-, or LPS + CoCl₂-stimulated adipocytes, PT reduced mRNA expression and/or secreted protein levels of inflammatory and macrophage chemotactic adipokines, and increased that of anti-inflammatory and angiogenic adipokines, which was consistent with reduced mRNA expression of M1 polarization markers and increased M2 markers in RAW 264.7 macrophages cultured in media collected from LPS + CoCl₂-simulated adipocytes (p < 0.05). Further, within LPS + CoCl₂-stimulated adipocytes, PT reduced reactive oxygen species accumulation, nuclear factor-κB activation, and apoptotic protein expression (p < 0.05). Overall, apple flavonols attenuate critical aspects of the obese AT phenotype.

Angiogenesis in obesity

PURPOSE

Angiogenesis is considered as a major progenitor in the progression of obesity. The current manuscript enumerates the extrinsic role of angiogenesis in obesity.

RESULT

High caloric diet and lack of physical exercise are the most common causes of obesity and related metabolic conditions. A grossly elevated levels of fat in adipose tissue escalate certain complications which further worsen the state of obesity. Enlargement of white adipose tissue (WAT), deposition of fat mass, proliferation of endothelial cells, production of inflammatory cytokines induces the formation of denovo capillaries from parent microvasculature. Also, several intracellular signaling pathways precipitate obesity. Though, angiostatic molecules (endostatin, angiostatin and TNP-470) have been designed to combat obesity and associated complications.

CONCLUSION

Adipose tissue trigger growth of blood capillaries, and in turn adipose tissue endothelial cells promote pre-adipocyte proliferation. Modulation of angiogenesis and treatment with angiostatic substances may have the potential to impair the progression of obesity.

Through fat and thin – a journey with the adipose tissues

The paper is based on the lecture that I gave on receiving the Nutrition Society's inaugural Gowland Hopkins Award for contributions to Cellular and Molecular Nutrition. It reviews studies on the adipose tissues, brown and white, conducted by the groups that I have led since entering nutrition research in 1975. The initial focus was on exploring metabolic factors that underpin the development of obesity using animal models. This resulted in an interest in non-shivering thermogenesis with brown adipose tissue being identified as the key effector of facultative heat production. Brown fat is less thermogenically active in various obese rodents, and major changes in activity are exhibited under physiological conditions such as lactation and fasting consistent with a general role for the tissue in nutritional energetics. My interests moved to white adipose tissue following the cloning of the Ob gene. Our initial contributions in this area included demonstrating nutritional regulation of Ob gene expression and circulating leptin levels, as well as a regulatory role for the sympathetic nervous system operating through β3-adrenoceptors. My interests subsequently evolved to a wider concern with the endocrine/signalling role of adipose tissue. Inflammation is a characteristic of white fat in obesity with the release of inflammation-related adipokines, and we proposed that hypoxia underlies this inflammatory state. O2-deprivation was shown to have substantial effects on gene expression and cellular function in white adipocytes. The hypoxia studies led to the proposition that O2 should be considered as a critical macronutrient.

Intermittent Hypoxia Stimulates Lipolysis, But Inhibits Differentiation and De Novo Lipogenesis in 3T3-L1 Cells

Background: Exposure to intermittent hypoxia (IH) may play a role in the development of metabolic impairments in the context of obstructive sleep apnea syndrome, probably by elevated plasma levels of free fatty acids. Employing gas-permeable cultureware to grow differentiated human and mouse adipocytes in vitro, we directly studied the effects of pericellular oxygen fluctuations on key adipocyte metabolic functions-spontaneous lipolytic rates, triglyceride accumulation, de novo lipogenesis, and expression of adipocyte-specific marker genes. Materials and Methods: 3T3-L1 fibroblasts and human subcutaneous preadipocytes were differentiated under conditions that induced repetitive pericellular-oxygen cycles IH between 1% O₂ (5 min) and 16% O₂ (5 min), continuously for 14 days or under control conditions. Chemicals were used to inhibit the flux of acetyl-CoA from glycolysis (alfa-cyano-4-hydroxy cinnamate) or the tricarboxylic acid cycle (SB204990), or to stimulate the flux of acetyl-CoA from pyruvate to the lipogenic pool. Lipolytic rate, intracellular lipids, and expression of adipocyte differentiation markers were assessed and t-test or ANOVA were used to find significant differences. Results: The rate of lipolysis increased by 211% in 3T3-L1 cells and by 39% in obese human adipocytes. Exposure to IH reduced intracellular lipid stores by 37% and reduced the expression of adipocyte differentiation markers. Pharmacological stimulation or inhibition of de novo lipogenesis did not modify the intracellular lipid content under IH. Conclusions: Pericellular oxygen fluctuations directly stimulated lipolysis, but did not increase de novo lipogenesis from endogenous substrates. Similarly, IH hampered adipocyte differentiation from precursors.

Oxygenation of adipose tissue: A human perspective

Obesity is a complex disorder of excessive adiposity, and is associated with adverse health effects such as cardiometabolic complications, which are to a large extent attributable to dysfunctional white adipose tissue. Adipose tissue dysfunction is characterized by adipocyte hypertrophy, impaired adipokine secretion, a chronic low‐grade inflammatory status, hormonal resistance and altered metabolic responses, together contributing to insulin resistance and related chronic diseases. Adipose tissue hypoxia, defined as a relative oxygen deficit, in obesity has been proposed as a potential contributor to adipose tissue dysfunction, but studies in humans have yielded conflicting results. Here, we will review the role of adipose tissue oxygenation in the pathophysiology of obesity‐related complications, with a specific focus on human studies. We will provide an overview of the determinants of adipose tissue oxygenation, as well as the role of adipose tissue oxygenation in glucose homeostasis, lipid metabolism and inflammation. Finally, we will discuss the putative effects of physiological and experimental hypoxia on adipose tissue biology and whole‐body metabolism in humans. We conclude that several lines of evidence suggest that alteration of adipose tissue oxygenation may impact metabolic homeostasis, thereby providing a novel strategy to combat chronic metabolic diseases in obese humans.

Hypoxia and exercise interactions on skeletal muscle insulin sensitivity in obese subjects with metabolic syndrome: results of a randomized controlled trial

BACKGROUND

Physical activity improves insulin sensitivity in obesity. Hypoxia training is claimed to augment this effect. We tested the hypothesis that normobaric hypoxia training would improve insulin sensitivity in obese patients with metabolic syndrome.

METHODS

In a randomized controlled trial, 23 obese men with metabolic syndrome who were not informed of the FiO₂ conditions underwent a 6-week physical exercise intervention under ambient (n = 11; FiO₂ 21%) conditions or hypoxia (n = 12; FiO₂ 15%) using a normobaric hypoxic chamber. Three 60-min sessions of interval training were performed each week at 60% of individual V̇O_2max. Assessment of myocellular insulin sensitivity by euglycemic hyperinsulinemic clamp was performed in 21 of these subjects before and after 6 weeks of training. Comprehensive phenotyping also included biopsies of subcutaneous adipose tissues.

RESULTS

The intermittent moderate physical exercise protocol did not substantially change the myocellular insulin sensitivity within 6 weeks under normoxic conditions (ISI_Clamp: 0.035 (IQR 0.016-0.075) vs. 0.037 (IQR 0.026-0.056) mg* kg^-1 *min^-1/(mU* l^-1); p = 0.767). In contrast, ISI_Clamp improved during hypoxia training (0.028 (IQR 0.018-0.035) vs. 0.038 (IQR 0.024-0.060) mg * kg^-1 *min^-1/(mU *l^-1); p < 0.05). Between group comparison of ISI_Clamp change revealed a small difference between groups (Cohen's d = 0.26). Within the hypoxic group, improvement of ISI_Clamp during training was associated with individual increase of circulating vascular endothelial growth factor (VEGF) levels (r = 0.678, p = 0.015), even if mean VEGF levels were not modified by any training condition. Atrial natriuretic peptide (ANP) system components were not associated with increased ISI_Clamp during hypoxic training.

CONCLUSIONS

Physical training under hypoxic conditions could partially augment the favorable effects of exercise alone on myocellular insulin sensitivity in obese men with metabolic syndrome. Concomitant changes in VEGF might represent an underlying pathophysiological mechanism.

High released lactate by epicardial fat from coronary artery disease patients is reduced by dapagliflozin treatment

BACKGROUND AND AIMS

Dapagliflozin, a sodium-glucose co-transporter 2 inhibitor, improves glucose uptake by epicardial adipose tissue (EAT). However, its metabolism might raise the lactate production and acidosis under hypoxia conditions, i.e. coronary artery disease (CAD), or lipogenesis and, in consequence, expand adipose tissue. Since lactate secreted by adipose tissue is correlated with tissue stress and inflammation, our aim was to study glucose metabolism by epicardial fat in CAD and its regulation by dapagliflozin.

METHODS

Paired EAT and subcutaneous adipose tissue (SAT) biopsies from 49 patients who underwent open-heart surgery were cultured and split into three equal pieces, some treated with and others without dapagliflozin at 10 or 100 μM for 6 h. Anaerobic glucose metabolites were measured in supernatants of fat pads, and acidosis on adipogenesis-induced primary culture cells was analysed by colorimetric or fluorescence assays. Gene expression levels were assessed by real-time polymerase chain reaction.

RESULTS

Our results showed that dapagliflozin reduced the released lactate and acidosis in epicardial fat (p < 0.05) without changes in lipid storage-involved genes. In addition, this drug induced gene expression levels of peroxisome proliferator-activated receptor gamma coactivator 1 alpha (PGC1α), a mitochondrial biogenesis-involved gene in both EAT and SAT (p < 0.05). After splitting the population regarding the presence of CAD, we observed higher lactate production in EAT from these patients (2.46 [1.75-3.47] mM), which was reduced after treatment with dapagliflozin 100 μM (1.99 [1.08-2.99] mM, p < 0.01).

CONCLUSIONS

Dapagliflozin improved glucose metabolism without lipogenesis-involved gene regulation or lactate production, mainly in patients with CAD. These results suggest an improvement of glucose oxidation metabolism that can contribute to cardiovascular benefits.

Mechanistic Links Between Obesity, Diabetes, and Blood Pressure: Role of Perivascular Adipose Tissue

Obesity is increasingly prevalent and is associated with substantial cardiovascular risk. Adipose tissue distribution and morphology play a key role in determining the degree of adverse effects, and a key factor in the disease process appears to be the inflammatory cell population in adipose tissue. Healthy adipose tissue secretes a number of vasoactive adipokines and anti-inflammatory cytokines, and changes to this secretory profile will contribute to pathogenesis in obesity. In this review, we discuss the links between adipokine dysregulation and the development of hypertension and diabetes and explore the potential for manipulating adipose tissue morphology and its immune cell population to improve cardiovascular health in obesity.

Pathobiological mechanisms underlying metabolic syndrome (MetS) in chronic obstructive pulmonary disease (COPD): clinical significance and therapeutic strategies

Chronic obstructive pulmonary disease (COPD) is a major incurable global health burden and is currently the 4th largest cause of death in the world. Importantly, much of the disease burden and health care utilisation in COPD is associated with the management of its comorbidities (e.g. skeletal muscle wasting, ischemic heart disease, cognitive dysfunction) and infective viral and bacterial acute exacerbations (AECOPD). Current pharmacological treatments for COPD are relatively ineffective and the development of effective therapies has been severely hampered by the lack of understanding of the mechanisms and mediators underlying COPD. Since comorbidities have a tremendous impact on the prognosis and severity of COPD, the 2015 American Thoracic Society/European Respiratory Society (ATS/ERS) Research Statement on COPD urgently called for studies to elucidate the pathobiological mechanisms linking COPD to its comorbidities. It is now emerging that up to 50% of COPD patients have metabolic syndrome (MetS) as a comorbidity. It is currently not clear whether metabolic syndrome is an independent co-existing condition or a direct consequence of the progressive lung pathology in COPD patients. As MetS has important clinical implications on COPD outcomes, identification of disease mechanisms linking COPD to MetS is the key to effective therapy. In this comprehensive review, we discuss the potential mechanisms linking MetS to COPD and hence plausible therapeutic strategies to treat this debilitating comorbidity of COPD.

Obesidade: uma abordagem inflamatória e microbiana

A obesidade está intimamente ligada ao estado inflamatório, sendo considerada uma patologia metabólica complexa. Dietas hipercalóricas alteram a composição da microbiota intestinal, sendo a mudança da proporção de bactérias dos filos Bacteroidetes e Firmicutes uma das consequências mais conhecidas.  Essa mudança determina a produção de metabólitos específicos do sistema imune, induzindo estado inflamatório responsável pelo agravamento de uma série de doenças. A dieta hipercalórica representa um fator de risco para a obesidade e para o diabetes mellitus, doenças interligadas pelo conceito de lipotoxicidade, e o estado inflamatório também contribui para o aparecimento e para a progressão de doenças cardiovasculares. Com esse artigo, objetivamos estudar a obesidade pela perspectiva imunológica e microbiológica, abordando as consequências de dietas hipercalóricas sobre o estado inflamatório e a sobre a microbiota. Ademais, associar a mudança no microbioma a doenças prevalentes como o diabetes mellitus e as doenças cardiovasculares, apontando abordagens terapêuticas potenciais.

Oxygen-A Critical, but Overlooked, Nutrient

Gaseous oxygen is essential for all aerobic animals, without which mitochondrial respiration and oxidative phosphorylation cannot take place. It is not, however, regarded as a "nutrient" by nutritionists and does not feature as such within the discipline of nutritional science. This is primarily a consequence of the route by which O₂ enters the body, which is via the nose and lungs in terrestrial animals as opposed to the mouth and gastrointestinal tract for what are customarily considered as nutrients. It is argued that the route of entry should not be the critical factor in defining whether a substance is, or is not, a nutrient. Indeed, O₂ unambiguously meets the standard dictionary definitions of a nutrient, such as "a substance that provides nourishment for the maintenance of life and for growth" (Oxford English Dictionary). O₂ is generally available in abundance, but deficiency occurs at high altitude and during deep sea dives, as well as in lung diseases. These impact on the provision at a whole-body level, but a low pO₂ is characteristic of specific tissues includings the retina and brain, while deficiency, or overt hypoxia, is evident in certain conditions such as ischaemic disease and in tumours - and in white adipose tissue in obesity. Hypoxia results in a switch from oxidative metabolism to increased glucose utilisation through anaerobic glycolysis, and there are extensive changes in the expression of multiple genes in O₂-deficient cells. These changes are driven by hypoxia-sensitive transcription factors, particularly hypoxia-inducible factor-1 (HIF-1). O₂ deficiency at a whole-body level can be treated by therapy or supplementation, but O₂ is also toxic through the generation of reactive oxygen species. It is concluded that O₂ is a critical, but overlooked, nutrient which should be considered as part of the landscape of nutritional science.

An update on immune dysregulation in obesity-related insulin resistance

Obesity is associated with chronic low-grade inflammation of the adipose tissue (AT) that might develop into systemic inflammation, insulin resistance (IR) and an increased risk of type 2 diabetes mellitus (T2DM) in severe obese rodents and humans. In the lean state, small normal adipocytes and AT macrophages interact with each other to maintain metabolic homeostasis but during obesity, enlarged adipocytes secrete inflammatory mediators and express immune receptors to recruit immune cells and aggravate the inflammation. The better understanding of the obesity-related inflammatory milieu and the sequential events leading to IR could be helpful in designing new preventive and therapeutic strategies. The present review will discuss the cellular and molecular abnormalities participating in the pathogenesis of obesity in obese individuals as well as high-fat diet (HFD)-fed mice, a mouse model of obesity.

Obesity and gastrointestinal cancer: the interrelationship of adipose and tumour microenvironments

Increasing recognition of an association between obesity and many cancer types exists, but how the myriad of local and systemic effects of obesity affect key cellular and non-cellular processes within the tumour microenvironment (TME) relevant to carcinogenesis, tumour progression and response to therapies remains poorly understood. The TME is a complex cellular environment in which the tumour exists along with blood vessels, immune cells, fibroblasts, bone marrow-derived inflammatory cells, signalling molecules and the extracellular matrix. Obesity, in particular visceral obesity, might fuel the dysregulation of key pathways relevant to both the adipose microenvironment and the TME, which interact to promote carcinogenesis in at-risk epithelium. The tumour-promoting effects of obesity can occur at the local level as well as systemically via circulating inflammatory, growth factor and metabolic mediators associated with adipose tissue inflammation, as well as paracrine and autocrine effects. This Review explores key pathways linking visceral obesity and gastrointestinal cancer, including inflammation, hypoxia, altered stromal and immune cell function, energy metabolism and angiogenesis.

Effect of cupuassu butter on human skin cells

This study investigated the effect of cupuassu butter on the cell number of human skin fibroblasts, as well as the gene expression profiles of certain growth factors in these fibroblasts. Cupuassu butter is a triglyceride composed of saturated and unsaturated fatty acids extracted from the fruit of Theobroma grandiflorum. The dataset includes expression profiles for genes encoding basic fibroblast growth factor (bFGF), stem cell factor (SCF), vascular endothelial growth factor (VEGF), hepatocyte growth factor (HGF), fibroblast growth factor-7 (FGF7), and epidermal growth factor (EGF). Cell viability profile is presented as a line graph, and the expression profiles are shown as bar graphs. Furthermore, this article also describes the effects of cupuassu butter on wound healing in vitro. The wound healing effects are shown as a bar graph accompanied with representative microscopic images.

Gestational Hypoxia and Developmental Plasticity

Hypoxia is one of the most common and severe challenges to the maintenance of homeostasis. Oxygen sensing is a property of all tissues, and the response to hypoxia is multidimensional involving complicated intracellular networks concerned with the transduction of hypoxia-induced responses. Of all the stresses to which the fetus and newborn infant are subjected, perhaps the most important and clinically relevant is that of hypoxia. Hypoxia during gestation impacts both the mother and fetal development through interactions with an individual's genetic traits acquired over multiple generations by natural selection and changes in gene expression patterns by altering the epigenetic code. Changes in the epigenome determine "genomic plasticity," i.e., the ability of genes to be differentially expressed according to environmental cues. The genomic plasticity defined by epigenomic mechanisms including DNA methylation, histone modifications, and noncoding RNAs during development is the mechanistic substrate for phenotypic programming that determines physiological response and risk for healthy or deleterious outcomes. This review explores the impact of gestational hypoxia on maternal health and fetal development, and epigenetic mechanisms of developmental plasticity with emphasis on the uteroplacental circulation, heart development, cerebral circulation, pulmonary development, and the hypothalamic-pituitary-adrenal axis and adipose tissue. The complex molecular and epigenetic interactions that may impact an individual's physiology and developmental programming of health and disease later in life are discussed.

Fibroblast and keratinocyte gene expression following exposure to the extracts of holy basil plant (Ocimum tenuiflorum), malabar nut plant (Justicia adhatoda), and emblic myrobalan plant (Phyllanthus emblica)

This data article provides gene expression profiles, determined by using real-time PCR, of fibroblasts and keratinocytes treated with 0.01% and 0.001% extracts of holy basil plant (Ocimum tenuiflorum), sri lankan local name “maduruthala”, 0.1% and 0.01% extracts of malabar nut plant (Justicia adhatoda), sri lankan local name “adayhoda” and 0.003% and 0.001% extracts of emblic myrobalan plant (Phyllanthus emblica), sri lankan local name “nelli”, harvested in Sri Lanka. For fibroblasts, the dataset includes expression profiles for genes encoding hyaluronan synthase 1 (HAS1), hyaluronan synthase 2 (HAS2), hyaluronidase-1 (HYAL1), hyaluronidase-2 (HYAL2), versican, aggrecan, CD44, collagen, type I, alpha 1 (COL1A1), collagen, type III, alpha 1 (COL3A1), collagen, type VII, alpha 1 (COL7A1), matrix metalloproteinase 1 (MMP1), acid ceramidase, basic fibroblast growth factor (bFGF), fibroblast growth factor-7 (FGF7), vascular endothelial growth factor (VEGF), interleukin-1 alpha (IL-1α), cyclooxygenase-2 (cox2), transforming growth factor beta (TGF-β), and aquaporin 3 (AQP3). For keratinocytes, the expression profiles are for genes encoding HAS1, HAS2, HYAL1, HYAL2, versican, CD44, IL-1α, cox2, TGF-β, AQP3, Laminin5, collagen, type XVII, alpha 1 (COL17A1), integrin alpha-6 (ITGA6), ceramide synthase 3 (CERS3), elongation of very long chain fatty acids protein 1 (ELOVL1), elongation of very long chain fatty acids protein 4 (ELOVL4), filaggrin (FLG), transglutaminase 1 (TGM1), and keratin 1 (KRT1). The expression profiles are provided as bar graphs.

Elevated (Pro)renin Receptor Expression Contributes to Maintaining Aerobic Metabolism in Growth Hormone Deficiency

Context

Growth hormone deficiency (GHD) leads to obesity and may induce tissue hypoxia. As (pro)renin receptor [(P)RR] is reported to contribute to the aerobic metabolism by stabilizing pyruvate dehydrogenase (PDH), it may play a substantial role in GHD.

Objective

We aimed to investigate serum soluble (P)RR [s(P)RR] concentration, the origin of s(P)RR, and significance of (P)RR in GHD.

Design, Setting, and Participants

Serum s(P)RR concentration was examined in 72 patients with pituitary diseases, including 32 patients with severe GHD (SGHD) and after GH replacement in 16 SGHD patients. Leptin-deficient ob/ob obese mice were treated with pegvisomant, a GH receptor antagonist, to explore the source of elevated serum s(P)RR in GHD. Adipocytes were cultured with 5% O₂ to examine the effects of hypoxia.

Results

Serum s(P)RR concentration was higher in patients with SGHD than in those without SGHD. Obesity was the important determinant of s(P)RR concentration. Serum s(P)RR concentration significantly decreased after GH replacement in SGHD patients. (P)RR mRNA expression was increased specifically in the adipose tissue (AT) of pegvisomant-treated obese mice compared with that of control obese mice. Hypoxia in cultured adipocytes increased (P)RR expression without affecting the PDH E1 β subunit (PDHB) expression; however, with (P)RR knockdown by small interfering RNA, hypoxia significantly decreased the expression of PDHB.

Conclusion

GHD patients showed increased serum s(P)RR concentration, possibly caused by obesity and hypoxia. (P)RR expression in AT of GHD patients may be elevated to help maintain aerobic metabolism under hypoxia. Thus, the elevated serum s(P)RR level may reflect hypoxia in ATs.

Fibroblast and keratinocyte gene expression following exposure to extracts of neem plant (Azadirachta indica)

This data article provides gene expression profiles, determined by using real-time PCR, of fibroblasts and keratinocytes treated with 0.01% and 0.001% extracts of neem plant (Azadirachta indica), local name “Kohomba” in Sri Lanka, harvested in Sri Lanka. For fibroblasts, the dataset includes expression profiles for genes encoding hyaluronan synthase 1 (HAS1), hyaluronan synthase 2 (HAS2), hyaluronidase-1 (HYAL1), hyaluronidase-2 (HYAL2), versican, aggrecan, CD44, collagen, type I, alpha 1 (COL1A1), collagen, type III, alpha 1 (COL3A1), collagen, type VII, alpha 1 (COL7A1), matrix metalloproteinase 1 (MMP1), acid ceramidase, basic fibroblast growth factor (bFGF), fibroblast growth factor-7 (FGF7), vascular endothelial growth factor (VEGF), interleukin-1 alpha (IL-1α), cyclooxygenase-2 (cox2), transforming growth factor beta (TGF-β), and aquaporin 3 (AQP3). For keratinocytes, the expression profiles are for genes encoding HAS1, HAS2, HYAL1, HYAL2, versican, CD44, IL-1α, cox2, TGF-β, AQP3, Laminin5, collagen, type XVII, alpha 1 (COL17A1), integrin alpha-6 (ITGA6), ceramide synthase 3 (CERS3), elongation of very long chain fatty acids protein 1 (ELOVL1), elongation of very long chain fatty acids protein 4 (ELOVL4), filaggrin (FLG), transglutaminase 1 (TGM1), and keratin 1 (KRT1). The expression profiles are provided as bar graphs.

[Research progress of correlation between traumatic brain injury and fracture healing]

Objective

To review the current status and advances of the correlation between traumatic brain injury (TBI) and fracture healing.

Methods

The related domestic and abroad literature about the correlation between TBI and fracture healing was extensively reviewed and analyzed.

Results

There are a variety of studies on the correlation between TBI and fracture healing, which can be divided into two major aspects: revascularization and osteogenesis; the local and systemic changes of the neuropeptide and hormone after TBI.

Conclusion

TBI facilitates callus formation, the further research is needed to clarify the exact mechanism.

Adipose Tissue Hypoxia in Obesity and Its Impact on Preadipocytes and Macrophages: Hypoxia Hypothesis

Obese subjects exhibit lower adipose tissue oxygen consumption in accordance with the lower adipose tissue blood flow. Thus, compared with lean subjects, obese subjects have 44% lower capillary density and 58% lower vascular endothelial growth factor (VEGF). The VEGF expression together with hypoxia-inducible transcription factor-1 (HIF-1) activity also requires phosphatidylinositol 3-kinase (PI3K)- and target of rapamycin (TOR)-mediated signaling. HIF-1alpha is an important signaling molecule for hypoxia to induce the inflammatory responses. Hypoxia affects a number of biological functions, such as angiogenesis, cell proliferation, apoptosis, inflammation and insulin resistance. Additionally, reactive oxygen radical (ROS) generation at mitochondria is responsible for propagation of the hypoxic signal. Actually mitochondrial ROS (mtROS) production, but not oxygen consumption is required for hypoxic HIF-1alpha protein stabilization. Adipocyte mitochondrial oxidative capacity is reduced in obese compared with non-obese adults. In this respect, mitochondrial dysfunction of adipocyte is associated with the overall adiposity. Furthermore, hypoxia also inhibits macrophage migration from the hypoxic adipose tissue. Alterations in oxygen availability of adipose tissue directly affect the macrophage polarization and are responsible from dysregulated adipocytokines production in obesity. Hypoxia also inhibits adipocyte differentiation from preadipocytes. In addition to stressed adipocytes, hypoxia contributes to immune cell immigration and activation which further aggravates adipose tissue fibrosis. Fibrosis is initiated in response to adipocyte hypertrophy in obesity.

Hypoxia-regulated mechanisms in the pathogenesis of obesity and non-alcoholic fatty liver disease

The pandemic rise in obesity has resulted in an increased incidence of metabolic complications. Non-alcoholic fatty liver disease is the hepatic manifestation of the metabolic syndrome and has become the most common chronic liver disease in large parts of the world. The adipose tissue expansion and hepatic fat accumulation characteristics of these disorders compromise local oxygen homeostasis. The resultant tissue hypoxia induces adaptive responses to restore oxygenation and tissue metabolism and cell survival. Hypoxia-inducible factors (HIFs) function as master regulators of this hypoxia adaptive response, and are in turn hydroxylated by prolyl hydroxylases (PHDs). PHDs are the main cellular oxygen sensors and regulate HIF proteasomal degradation in an oxygen-dependent manner. HIFs and PHDs are implicated in numerous physiological and pathological conditions. Extensive research using genetic models has revealed that hypoxia signaling is also a key mechanism in adipose tissue dysfunction, leading to adipose tissue fibrosis, inflammation and insulin resistance. Moreover, hypoxia affects liver lipid metabolism and deranges hepatic lipid accumulation. This review summarizes the molecular mechanisms through which the hypoxia adaptive response affects adipocyte and hepatic metabolism, and the therapeutic possibilities of modulating HIFs and PHDs in obesity and fatty liver disease.

Adipogenesis, lipogenesis and lipolysis is stimulated by mild but not severe hypoxia in 3T3-L1 cells

In-vitro investigation of the effects of hypoxia is limited by physical laws of gas diffusion and cellular O2 consumption, making prolonged exposures to stable O2 concentrations impossible. Using a gas-permeable cultureware, chronic effects of mild and severe hypoxia on triglyceride accumulation, lipid droplet size distribution, spontaneous lipolysis and gene expression of adipocyte-specific markers were assessed. 3T3-L1 cells were differentiated under 20%, 4% or 1% O2 using a gas-permeable cultureware. Triglyceride accumulation, expression of genes characteristic for advanced adipocyte differentiation and involvement of key lipogenesis enzymes were assessed after exposures. Lipogenesis increased by 375% under mild hypoxia, but dropped by 43% in severe hypoxia. Mild, but not severe, hypoxia increased formation of large lipid droplets 6.4 fold and strongly induced gene expression of adipocyte-specific markers. Spontaneous lipolysis increased by 488% in mild, but only by 135% in severe hypoxia. Inhibition of ATP-dependent citrate lyase suppressed hypoxia-induced lipogenesis by 81% and 85%. Activation of HIF inhibited lipogenesis by 59%. Mild, but not severe, hypoxia stimulates lipolysis and promotes adipocyte differentiation, probably through excess of acetyl-CoA originating from tricarboxylic acid cycle independently of HIF activation.

Blockade of the renin-angiotensin system in small arteries and anticontractile function of perivascular adipose tissue

BACKGROUND/AIMS

In patients with obesity, there is increased inflammation with attendant oxidative stress in perivascular adipose tissue. This has functional consequences with loss of vasodilator adipokine bioavailability. Part of the inflammatory response is mediated by increased activation of the renin-angiotensin-aldosterone axis. Therefore, this study was designed to investigate whether angiotensin-converting enzyme inhibitors or angiotensin receptor blockers can improve the anticontractile function of perivascular adipose tissue.

METHODS

Segments of rat mesenteric small artery were dissected and mounted in a wire myograph and contracted to incremental doses of norepinephrine in the presence and absence of perivascular adipose tissue and in conditions of normal oxygenation or after hypoxia and incubated with captopril or telmisartan.

RESULTS

Vessels with perivascular adipose tissue contracted significantly less than arteries with perivascular adipose tissue removed under normal oxygenation conditions, indicating that perivascular adipose tissue exerts an anticontractile effect. Hypoxia induced a loss of this anticontractile effect which could be completely prevented with captopril or telmisartan.

CONCLUSION

The in-vitro creation of a hypoxic environment can simulate the loss of anticontractile perivascular adipose tissue function seen in vivo in obese patients, and this can be prevented using inhibitors of the renin-angiotensin cascade.

Tissue Factor-Factor VII Complex As a Key Regulator of Ovarian Cancer Phenotypes

Tissue factor (TF) is an integral membrane protein widely expressed in normal human cells. Blood coagulation factor VII (fVII) is a key enzyme in the extrinsic coagulation cascade that is predominantly secreted by hepatocytes and released into the bloodstream. The TF–fVII complex is aberrantly expressed on the surface of cancer cells, including ovarian cancer cells. This procoagulant complex can initiate intracellular signaling mechanisms, resulting in malignant phenotypes. Cancer tissues are chronically exposed to hypoxia. TF and fVII can be induced in response to hypoxia in ovarian cancer cells at the gene expression level, leading to the autonomous production of the TF–fVII complex. Here, we discuss the roles of the TF–fVII complex in the induction of malignant phenotypes in ovarian cancer cells. The hypoxic nature of ovarian cancer tissues and the roles of TF expression in endometriosis are discussed. Arguments will be extended to potential strategies to treat ovarian cancers based on our current knowledge of TF–fVII function.