Oxygenation of adipose tissue: A human perspective

linc-ADAIN, a human adipose lincRNA, regulates adipogenesis by modulating KLF5 and IL-8 mRNA stability

Adipose tissue remodeling and dysfunction, characterized by elevated inflammation and insulin resistance, play a central role in obesity-related development of type 2 diabetes (T2D) and cardiovascular diseases. Long intergenic non-coding RNAs (lincRNAs) are important regulators of cellular functions. Here, we describe the functions of linc-ADAIN (adipose anti-inflammatory), an adipose lincRNA that is downregulated in white adipose tissue of obese humans. We demonstrate that linc-ADAIN knockdown (KD) increases KLF5 and interleukin-8 (IL-8) mRNA stability and translation by interacting with IGF2BP2. Upregulation of KLF5 and IL-8, via linc-ADAIN KD, leads to an enhanced adipogenic program and adipose tissue inflammation, mirroring the obese state, in vitro and in vivo. KD of linc-ADAIN in human adipose stromal cell (ASC) hTERT adipocytes implanted into mice increases adipocyte size and macrophage infiltration compared to implanted control adipocytes, mimicking hallmark features of obesity-induced adipose tissue remodeling. linc-ADAIN is an anti-inflammatory lincRNA that limits adipose tissue expansion and lipid storage.

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 .

Energy expenditure related biomarkers following bariatric surgery: a prospective six-month cohort study

BACKGROUND

Mitochondria dysfunction is one of the major causes of insulin resistance, and other countless complications of obesity. PGC-1α, and UCP-2 play key roles in energy expenditure regulation in the mitochondrial thermogenesis. However, the effects of bariatric surgery on the level of PGC-1α and UCP-2 and their relationships are unclear.

OBJECTIVE

This study aimed to investigate the effect of bariatric surgery on key pathways in energy, and to assess the potential predictive role of body composition and metabolic parameters in this regard.

SETTINGS

Hazrat-e Rasool General Hospital, Center of Excellence of International Federation for Surgery of Obesity.

METHODS

This prospective cohort study was carried out on 45 patients with morbid obesity who underwent Roux-en-Y gastric bypass surgery. The patients have evaluated three-time points at baseline, three, and six months after the surgery. Body composition components, the levels of PGC-1α, UCP-2, and metabolic parameters were measured three times during this study.

RESULTS

Significant changes in TWL%, EBMIL%, and metabolic lab tests were observed at three- and six months post-surgery (P < 0.001). The PGC-1α and UCP-2 had a significant increase three and then six-month post-operation compared with the baseline (P < 0.001). Moreover, multivariate linear regression analysis identified that the changing trend of PGC-1α was associated with insulin, uric Acid, HOMA-IR, fat mass and trunk fat mass. UCP-2 was associated with TSH, AST, fat mass and FFM.

CONCLUSIONS

Bariatric surgery has been shown to have a positive effect on UCP-2 and PGC-1α levels, as well as body composition and metabolic parameters. As a result, it is believed that bariatric surgery could improve thermogenesis and energy expenditure by enhancing mitochondrial biogenesis and function. However, further studies are needed to fully understand the precise mechanisms and possible causal relationship.

Lower glycemia levels in subjects with excessive erythrocytosis during the oral glucose tolerance test living in conditions of severe hypoxia

Background

Previous studies showed that residents of higher elevations have lower glucose levels. Our objective in this study is to determine the basal and postprandial glucose levels in apparently healthy permanent residents of the miner population center of La Rinconada located 5100 meters (m) above sea level.

Method

Forty male permanent residents of the Rinconada miner population center were studied. The oral glucose tolerance test was used to evaluate basal and postprandial glycemia levels at 1, 2, and 3 h.

Results

The individuals had a mean age of 43.95 ± 8.54 years. Basal glycemia in subjects without excessive erythrocytosis (EE) was 73.3 ± 7.9 mg/dL, while levels in patients with EE were 57.98 ± 7.38 mg/dL. In the postprandial period, at 1 h after oral glucose overload, a mean value of 76.35 ± 13.53 mg/dL was observed in subjects with EE compared to 94.68 ± 9.98 mg/dL in subjects without EE. After 2 h, subjects with EE had a glycemia level of 72.91 ± 9.17 mg/dL EE compared to 90.73 ± 13.86 mg/dL without EE. At 3 h, the average glycemia level in subjects with EE was 70.77 ± 8.73 mg/dL compared to 87.79 ± 14.16 mg/dL in those without EE.

Conclusion

These findings suggest that under hypoxic conditions, glycemia levels are lower in both subjects with and without EE, having obtained lower levels in subjects with EE in relation to those with normal values of Hb and Hct. The results of this study indicate that in the conditions of severe hypoxia, blood glucose levels are below the values considered normal for sea level.

Clinical and molecular profiling of human visceral adipose tissue reveals impairment of vascular architecture and remodeling as an early hallmark of dysfunction

Adipose tissue dysfunction is more related to insulin resistance than body mass index itself and an alteration in adipose tissue function is thought to underlie the shift from metabolically healthy to unhealthy obesity. Herein, we performed a clustering analysis that revealed distinct visceral adipose tissue gene expression patterns in patients with obesity at distinct stages of metabolic dysregulation. We have built a cross-sectional cohort that aims at reflecting the evolution of the metabolic sequelae of obesity with the main objective to map the sequential events that play a role in adipose tissue dysfunction from the metabolically healthy (insulin-sensitive) state to several incremental degrees of metabolic dysregulation, encompassing insulin resistance establishment, pre-diabetes, and type 2 diabetes. We found that insulin resistance is mainly marked by the downregulation of adipose tissue vasculature remodeling-associated gene expression, suggesting that processes like angiogenesis and adaptative expansion/retraction ability suffer early dysregulation. Prediabetes was characterized by compensatory growth factor-dependent signaling and increased response to hypoxia, while type 2 diabetes was associated with loss of cellular response to insulin and hypoxia and concomitant upregulation of inflammatory markers. Our findings suggest a putative sequence of dysregulation of biological processes that is not linear and has multiple distinct phases across the metabolic dysregulation process, ultimately culminating in the climax of adipose tissue dysfunction in type 2 diabetes. Several studies have addressed the transcriptomic changes in adipose tissue of patients with obesity. However, to the best of our knowledge, this is the first study unraveling the potential molecular mechanisms associated with the multi-step evolution of adipose tissue dysfunction along the metabolic sequelae of obesity.

White adipocyte dysfunction and obesity-associated pathologies in humans

The prevalence of obesity and associated chronic diseases continues to increase worldwide, negatively impacting on societies and economies. Whereas the association between excess body weight and increased risk for developing a multitude of diseases is well established, the initiating mechanisms by which weight gain impairs our metabolic health remain surprisingly contested. In order to better address the myriad of disease states associated with obesity, it is essential to understand adipose tissue dysfunction and develop strategies for reinforcing adipocyte health. In this Review we outline the diverse physiological functions and pathological roles of human white adipocytes, examining our current knowledge of why white adipocytes are vital for systemic metabolic control, yet poorly adapted to our current obesogenic environment.

Is the leptin/BMI ratio a reliable biomarker for endometriosis?

Background

The aim of this study was to analyze the concentration of leptin in peritoneal fluid and plasma and to assess their role as potential biomarkers in the diagnosis of endometriosis.

Materials & methods

Leptin adjusted for BMI (leptin/BMI ratio) was measured using surface plasmon resonance imaging (SPRI) biosensors. Patients with suspected endometriosis were included in the study. Plasma was collected from 70 cases, and peritoneal fluid from 67 cases. Based on the presence of endometriosis lesions detected during laparoscopy, patients were divided into a study group and a control group (patients without endometriosis).

Results

Leptin/BMI ratio in plasma did not differ between women with endometriosis and the control group (0.7159 ± 0.259 vs 0.6992 ± 0.273, p= 0,7988). No significant differences were observed in peritoneal leptin/BMI ratio levels in patients with and without endometriosis (0.6206 ± 0.258 vs 0.6215 ± 0.264, p= 0,9896). Plasma and peritoneal leptin/BMI ratios were significantly lower in women with endometriosis - related primary infertility compared to women with endometriosis without primary infertility (0.640 ± 0.502 vs 0.878 ± 0.623, p < 0.05). The difference was observed in case of primary infertility, but not in terms of the secondary one. No significant differences were noted between leptin/BMI ratio in the proliferative phase and the secretory phase (0.716 ± 0.252 vs 0.697 ± 0.288, p= 0,7785).

Conclusion

The results of present study do not support the relevance of leptin concentration determination as a biomarker of the endometriosis. Due to the limited number of samples in the tested group, further studies are needed to confirm its role.

Mulberry and Hippophae-based solid beverage promotes weight loss in rats by antagonizing white adipose tissue PPARγ and FGFR1 signaling

Obesity, a multifactorial disease with many complications, has become a global epidemic. Weight management, including dietary supplementation, has been confirmed to provide relevant health benefits. However, experimental evidence and mechanistic elucidation of dietary supplements in this regard are limited. Here, the weight loss efficacy of MHP, a commercial solid beverage consisting of mulberry leaf aqueous extract and Hippophae protein peptides, was evaluated in a high-fat high-fructose (HFF) diet-induced rat model of obesity. Body component analysis and histopathologic examination confirmed that MHP was effective to facilitate weight loss and adiposity decrease. Pathway enrichment analysis with differential metabolites generated by serum metabolomic profiling suggests that PPAR signal pathway was significantly altered when the rats were challenged by HFF diet but it was rectified after MHP intervention. RNA-Seq based transcriptome data also indicates that MHP intervention rectified the alterations of white adipose tissue mRNA expressions in HFF-induced obese rats. Integrated omics reveals that the efficacy of MHP against obesogenic adipogenesis was potentially associated with its regulation of PPARγ and FGFR1 signaling pathway. Collectively, our findings suggest that MHP could improve obesity, providing an insight into the use of MHP in body weight management.

The Metabolic Syndrome, a Human Disease

This review focuses on the question of metabolic syndrome (MS) being a complex, but essentially monophyletic, galaxy of associated diseases/disorders, or just a syndrome of related but rather independent pathologies. The human nature of MS (its exceptionality in Nature and its close interdependence with human action and evolution) is presented and discussed. The text also describes the close interdependence of its components, with special emphasis on the description of their interrelations (including their syndromic development and recruitment), as well as their consequences upon energy handling and partition. The main theories on MS's origin and development are presented in relation to hepatic steatosis, type 2 diabetes, and obesity, but encompass most of the MS components described so far. The differential effects of sex and its biological consequences are considered under the light of human social needs and evolution, which are also directly related to MS epidemiology, severity, and relations with senescence. The triggering and maintenance factors of MS are discussed, with especial emphasis on inflammation, a complex process affecting different levels of organization and which is a critical element for MS development. Inflammation is also related to the operation of connective tissue (including the adipose organ) and the widely studied and acknowledged influence of diet. The role of diet composition, including the transcendence of the anaplerotic maintenance of the Krebs cycle from dietary amino acid supply (and its timing), is developed in the context of testosterone and β-estradiol control of the insulin-glycaemia hepatic core system of carbohydrate-triacylglycerol energy handling. The high probability of MS acting as a unique complex biological control system (essentially monophyletic) is presented, together with additional perspectives/considerations on the treatment of this 'very' human disease.

Biological sex-related differences in the postprandial triglyceride response to intermittent hypoxaemia in young adults: a randomized crossover trial

Obstructive sleep apnoea is characterized by chronic intermittent hypoxaemia and is independently associated with an increased risk of metabolic comorbidities (e.g. type II diabetes and ischaemic heart disease). These comorbidities could be attributable to hypoxaemia-induced alterations in blood lipid profiles. However, it remains unclear whether intermittent hypoxaemia alters triglyceridaemia differently between biological sexes. Therefore, we used a randomized crossover design to examine whether 6 h of moderate intermittent hypoxaemia (15 hypoxaemic cycles/h, 85% oxyhaemoglobin saturation) alters plasma triglyceride levels differently between men and women after a high-fat meal. Relative to men, women displayed lower levels of total triglycerides, in addition to denser triglyceride-rich lipoprotein triglycerides (TRL-TG; mainly very low-density lipoprotein triglycerides and chylomicron remnant triglycerides) and buoyant TRL-TG (mainly chylomicron triglycerides) during normoxia (ambient air) and intermittent hypoxaemia (sex × time: all P ≤ 0.008). Intermittent hypoxaemia led to higher triglyceride levels (condition: all P ≤ 0.016); however, this effect was observed only in men (sex × condition: all P ≤ 0.002). Compared with normoxia, glucose levels were higher in men and lower in women during intermittent hypoxaemia (sex × condition: P < 0.001). The different postprandial responses between biological sexes occurred despite similar reductions in mean oxyhaemoglobin saturation and similar elevations in insulin levels, non-esterified fatty acid levels and mean heart rate (sex × condition: all P ≥ 0.185). These results support growing evidence showing that intermittent hypoxaemia impacts men and women differently, and they might help to explain biological sex-related discrepancies in the rate of certain comorbidities associated with intermittent hypoxaemia. KEY POINTS: Intermittent hypoxaemia is a key characteristic of obstructive sleep apnoea and alters lipid metabolism in multiple tissues, resulting in increased circulating triglyceride levels, an important risk factor for cardiometabolic diseases. Circulating triglyceride levels are regulated differently between biological sexes, with women typically displaying much lower fasting and postprandial triglyceride levels than men, partly explaining why women of all ages experience lower mortality rates from cardiometabolic diseases. In this study, healthy young men and women consumed a high-fat meal and were then exposed to 6 h of intermittent hypoxaemia or ambient air. We show that postprandial triglyceride levels are significantly lower in women compared with men and that intermittent hypoxaemia leads to higher postprandial triglyceride levels in men only. These results might help us to understand better why women living with obstructive sleep apnoea experience lower rates of cardiometabolic diseases (e.g. type II diabetes and ischaemic heart disease) than men living with obstructive sleep apnoea.

Influence of Breastfeeding on the State of Meta-Inflammation in Obesity-A Narrative Review

Obesity has become an emerging health issue worldwide that continues to grow in females of reproductive age as well. Obesity, as a multisystem and chronic disease, is associated with metabolic inflammation, which is defined as chronic low-grade systemic inflammation mediated by, i.a., adipose tissue macrophages. Lactation has been proven to have a beneficial influence on maternal health and could help restore metabolic balance, especially in the state of maternal obesity. In this review, we aimed to analyze the influence of breastfeeding on chronic low-grade meta-inflammation caused by obesity. We performed a comprehensive literature review using the PubMed, Science Direct, and Google Scholar electronic databases. For this purpose, we searched for "metabolic inflammation"; "meta-inflammation"; "obesity"; "breastfeeding"; "fetal programming"; "energy metabolism"; "postpartum"; "immunity"; "immune system"; and "inflammation" keyword combinations. While the clinical impact of breastfeeding on maternal and offspring health is currently well known, we decided to gain insight into more specific metabolic effects of adiposity, lipid, and glucose homeostasis, and immunological effects caused by the activity of cytokines, macrophages, and other immune system cells. Further research on the immunological and metabolic effects of breastfeeding in obese patients is key to understanding and potentially developing obesity therapeutic strategies.

Role of stress in the pathogenesis of cancer (Review)

Stress is a state of disrupted homeostasis, triggered by intrinsic or extrinsic factors, the stressors, which are counteracted by various physiological and behavioural adaptive responses. Stress has been linked to cancer development and incidence for decades; however, epidemiological studies and clinical trials have yielded contradictory results. The present review discusses the effects of stress on cancer development and the various underlying mechanisms. Animal studies have revealed a clear link between stress and cancer progression, revealing molecular, cellular and endocrine processes that are implicated in these effects. Thus, stress hormones, their receptor systems and their intracellular molecular pathways mediate the effects of stress on cancer initiation, progression and the development of metastases. The mechanisms linking stress and cancer progression can either be indirect, mediated by changes in the cancer microenvironment or immune system dysregulation, or direct, through the binding of neuroendocrine stress‑related signalling molecules to cancer cell receptors. Stress affects numerous anti‑ and pro‑cancer immune system components, including host resistance to metastasis, tumour retention and/or immune suppression. Chronic psychological stress through the elevation of catecholamine levels may increase cancer cell death resistance. On the whole, stress is linked to cancer development and incidence, with psychological stressors playing a crucial role. Animal studies have revealed a better link than human ones, with stress‑related hormones influencing tumour development, migration, invasion and cell proliferation. Randomized controlled trials are required to further evaluate the long‑term cancer outcomes of stress and its management.

Electroacupuncture activates angiogenesis by regulating the PI3K/Pten/Thbs1 signaling pathway to promote the browning of adipose tissue in HFD-induced obese mice

This study investigated the effect of electroacupuncture (EA) on the browning of white adipose tissue (WAT) via angiogenesis and its potential mechanism in obese mice. Four-week-old male C56BL/6 mice were randomly divided into a high-fat diet (HFD) and a normal chow diet (ND) group. After 12 weeks, HFD mice were randomly divided into two groups to receive or not receive EA for 3 weeks. After EA treatment, body weight, adipocyte size, serum glucose (GLU), triacylglycerol (TG), cholesterol (CHO), leptin (Lep), monocyte chemoattractant protein-1 (MCP-1), WAT browning-related genes, angiogenesis-related genes, and the PI3K/Pten/Thbs1 signaling pathway were evaluated. The results indicated that EA significantly reduced body weight, adipocyte size, and serum concentrations of GLU, TG, CHO, Lep and MCP-1 and promoted WAT browning. Angiogenesis and the PI3K/Pten/Thbs1 signaling pathway were all activated by EA intervention. The expression levels were consistent with the results of RNA-seq and confirmed via qRTPCR and WB. Our study showed that EA may activate angiogenesis via the PI3K/Pten/Thbs1 signaling pathway in WAT, thereby promoting the browning and thermogenesis of adipose tissue.

Engineered porosity for tissue-integrating, bioresorbable lifetime-based phosphorescent oxygen sensors

Versatile silk protein-based material formats were studied to demonstrate bioresorbable, implantable optical oxygen sensors that can integrate with the surrounding tissues. The ability to continuously monitor tissue oxygenation in vivo is desired for a range of medical applications. Silk was chosen as the matrix material due to its excellent biocompatibility, its unique chemistry that facilitates interactions with chromophores, and the potential to tune degradation time without altering chemical composition. A phosphorescent Pd (II) benzoporphyrin chromophore was incorporated to impart oxygen sensitivity. Organic solvent-based processing methods using 1,1,1,3,3,3-hexafluoro-2-propanol were used to fabricate: 1) silk-chromophore films with varied thickness and 2) silk-chromophore sponges with interconnected porosity. All compositions were biocompatible and exhibited photophysical properties with oxygen sensitivities (i.e., Stern-Volmer quenching rate constants of 2.7-3.2 × 104 M-1) useful for monitoring physiological tissue oxygen levels and for detecting deviations from normal behavior (e.g., hyperoxia). The potential to tune degradation time without significantly impacting photophysical properties was successfully demonstrated. Furthermore, the ability to consistently monitor tissue oxygenation in vivo was established via a multi-week rodent study. Histological assessments indicated successful tissue integration for the sponges, and this material format responded more quickly to various oxygen challenges than the film samples.

Meeting at the Crossroad between Obesity and Hepatic Carcinogenesis: Unique Pathophysiological Pathways Raise Expectations for Innovative Therapeutic Approaches

The escalating global prevalence of obesity and its intricate association with the development of hepatocellular carcinoma (HCC) pose a substantial challenge to public health. Obesity, acknowledged as a pervasive epidemic, is linked to an array of chronic diseases, including HCC, catalyzing the need for a comprehensive understanding of its molecular underpinnings. Notably, HCC has emerged as a leading malignancy with rising incidence and mortality. The transition from viral etiologies to the prominence of metabolic dysfunction-associated fatty liver disease (MAFLD)-related HCC underscores the urgent need to explore the intricate molecular pathways linking obesity and hepatic carcinogenesis. This review delves into the interwoven landscape of molecular carcinogenesis in the context of obesity-driven HCC while also navigating using the current therapeutic strategies and future prospects for combating obesity-related HCC. We underscore the pivotal role of obesity as a risk factor and propose an integrated approach encompassing lifestyle interventions, pharmacotherapy, and the exploration of emerging targeted therapies. As the obesity-HCC nexus continues to challenge healthcare systems globally, a comprehensive understanding of the intricate molecular mechanisms and innovative therapeutic strategies is imperative to alleviate the rising burden of this dual menace.

Obesity and Peripheral Artery Disease: Current Evidence and Controversies

PURPOSE OF REVIEW

Obesity is a significant public health problem and a major risk factor for the development and progression of atherosclerosis and its cardiovascular manifestations. Lower extremity peripheral artery disease (PAD) affects 3%-10% of the Western population and, if left untreated, can lead to devastating outcomes with both an increased risk of morbidity and mortality. Interestingly, the association between obesity and PAD remains debatable. Whereas it is well known that PAD and obesity frequently overlap in the same patients, many studies have demonstrated a negative association between obesity and PAD and a protective effect of obesity on disease development and progression, a phenomenon described as the "obesity paradox." Possible mechanisms for this paradox may include genetic background, as assessed by mendelian randomization studies, adipose tissue dysfunction, and body fat distribution rather than adiposity, while other factors, such as sex, ethnicity, sarcopenia in the elderly population, or aggressive treatment of co-existing metabolic conditions in individuals with obesity compared to those with normal weight, could have some impact as well.

RECENT RINDINGS

Few reviews and meta-analyses examining systematically the relationship between obesity and PAD exist. The impact of PAD development due to the presence of obesity remains largely controversial. However, the most current evidence, backed by a recent meta-analysis, suggests a potential protective role of a higher body mass index on PAD-related complications and mortality. In this review, we discuss the association between obesity and PAD development, progression, and management, and the potential pathophysiologic mechanisms linking the two diseases.

Fitness correlates of blubber oxidative stress and cellular defences in grey seals (Halichoerus grypus): support for the life-history-oxidative stress theory from an animal model of simultaneous lactation and fasting

Life-history-oxidative stress theory predicts that elevated energy costs during reproduction reduce allocation to defences and increase cellular stress, with fitness consequences, particularly when resources are limited. As capital breeders, grey seals are a natural system in which to test this theory. We investigated oxidative damage (malondialdehyde (MDA) concentration) and cellular defences (relative mRNA abundance of heat shock proteins (Hsps) and redox enzymes (REs)) in blubber of wild female grey seals during the lactation fast (n = 17) and summer foraging (n = 13). Transcript abundance of Hsc70 increased, and Nox4, a pro-oxidant enzyme, decreased throughout lactation. Foraging females had higher mRNA abundance of some Hsps and lower RE transcript abundance and MDA concentrations, suggesting they experienced lower oxidative stress than lactating mothers, which diverted resources into pup rearing at the expense of blubber tissue damage. Lactation duration and maternal mass loss rate were both positively related to pup weaning mass. Pups whose mothers had higher blubber glutathione-S-transferase (GST) expression at early lactation gained mass more slowly. Higher glutathione peroxidase (GPx) and lower catalase (CAT) were associated with longer lactation but reduced maternal transfer efficiency and lower pup weaning mass. Cellular stress, and the ability to mount effective cellular defences, could proscribe lactation strategy in grey seal mothers and thus affect pup survival probability. These data support the life-history-oxidative stress hypothesis in a capital breeding mammal and suggest lactation is a period of heightened vulnerability to environmental factors that exacerbate cellular stress. Fitness consequences of stress may thus be accentuated during periods of rapid environmental change.

Cardiometabolic effects of SGLT2 inhibitors on polycystic ovary syndrome

Polycystic ovary syndrome (PCOS) is a complex endocrinopathy affecting many women of reproductive age. Although its physiology is poorly understood, hyperandrogenemia and insulin resistance play a pivotal role in this complex syndrome, predisposing patients to a variety of cardiovascular and metabolic modalities. Current therapeutic options, including lifestyle modifications and medications, often do not satisfactorily improve clinical outcomes. SGLT2 inhibitors (SGLT-2i) are a novel option which can potentially improve many hormonal and metabolic parameters for patients with PCOS, though the net cardiovascular effects remain under investigation in this population of patients with PCOS. Overall, the use of SGLT-2i may be associated with beneficial somatometric, metabolic and hormonal outcomes of PCOS. To date, all available studies have recorded body mass index, waist and hip circumference, and fat mass reductions, improved insulin and androgen levels, and reduced blood pressure. The aim of the present review is to summarise PCOS-related manifestations and mechanisms leading to cardiovascular disease, to explore the cardiometabolic impact of SGLT2i on PCOS, and to critically analyse the cardiometabolic and hormonal outcomes of the recent studies on the use of SGLT2i in women with PCOS.

Distinct inflammatory signatures of upper and lower body adipose tissue and adipocytes in women with normal weight or obesity

Introduction

Upper and lower body fat accumulation poses an opposing obesity-related cardiometabolic disease risk. Depot-differences in subcutaneous adipose tissue (SAT) function may underlie these associations. We aimed to investigate the inflammatory signatures of abdominal (ABD) and femoral (FEM) SAT in postmenopausal women with normal weight or obesity.

Methods

We included 23 postmenopausal women with normal weight (n = 13) or obesity (n = 10). In vivo secretion of adipokines from ABD and FEM SAT was measured using the arterio-venous balance technique. Adipokine gene expression and adipocyte morphology were examined in ABD and FEM SAT. Furthermore, adipokine expression and secretion were investigated in vitro using differentiated human primary ABD and FEM subcutaneous adipocytes derived from the study participants.

Results

Plasma leptin and plasminogen activator inhibitor (PAI)-1 concentrations were higher, and ABD and FEM adipocytes were larger in women with obesity than normal weight. No differences in adipocyte size and blood flow were apparent between ABD and FEM SAT. We found significant release of leptin and monocyte chemoattractant protein (MCP)-1 from ABD and FEM SAT, with higher fractional release of MCP-1 from ABD than FEM SAT. Gene expression of leptin, PAI-1, and tumor necrosis factor-α was lower in ABD than FEM SAT and higher in women with obesity than normal weight. In ABD adipocytes, interleukin-6, PAI-1, and leptin gene expression were higher, while adiponectin and dipeptidyl-peptidase-4 gene expression were lower than in FEM adipocytes. Finally, ABD adipocytes secreted less MCP-1 compared to FEM adipocytes.

Discussion

These findings demonstrate that upper and lower body SAT and adipocytes are characterized by distinct inflammatory signatures in postmenopausal women, which seem independent of adipocyte size.

Physiopathological mechanisms related to inflammation in obesity and type 2 diabetes mellitus

Overweight, obesity, and type 2 diabetes mellitus pose global health problems that are ever-increasing. A chronic low-grade inflammatory status and the presence of various pro-inflammatory markers either in circulation or within dysfunctional metabolic tissues are well established. The presence of these factors can, to some extent, predict disease development and progression. A central role is played by the presence of dysfunctional adipose tissue, liver dysfunction, and skeletal muscle dysfunction, which collectively contribute to the increased circulatory levels of proinflammatory factors. Weight loss and classical metabolic interventions achieve a decrease in many of these factors’ circulating levels, implying that a better understanding of the processes or even the modulation of inflammation may alleviate these diseases. This review suggests that inflammation plays a significant role in the development and progression of these conditions and that measuring inflammatory markers may be useful for assessing disease risk and development of future treatment methods.

Implications of obesity and adiposopathy on respiratory infections; focus on emerging challenges

Obesity is characterized by excessive adipose tissue accumulation, which impacts physiological, metabolic, and immune functions. Several respiratory infections, including bacterial pneumonia, influenza, and coronavirus disease 2019, appear to be linked to unfavorable results in individuals with obesity. These may be attributed to the direct mechanical/physiological effects of excess body fat on the lungs’ function. Notably, adipose tissue dysfunction is associated with a low-grade chronic inflammatory status and hyperleptinemia, among other characteristics. These have all been linked to immune system dysfunction and weakened immune responses to these infections. A better understanding and clinical awareness of these risk factors are necessary for better disease outcomes.

COVID-19 and liver injury in individuals with obesity

Coronavirus disease 2019 is an infectious disease caused by the severe acute respiratory syndrome coronavirus 2 that manifests as a variety of clinical manifestations, including liver damage commonly detected by a hepatocellular pattern from liver function tests. Liver injury is associated with a worse prognosis overall. Conditions associated with the severity of the disease include obesity and cardiometabolic comorbidities, which are also associated with nonalcoholic fatty liver disease (NAFLD). The presence of NAFLD, similarly to obesity, is associated with an unfavourable impact on the coronavirus disease 2019 outcome. Individuals with these conditions could present with liver damage and elevated liver function tests due to direct viral cytotoxicity, systemic inflammation, ischemic or hypoxic liver damage or drug side effects. However, liver damage in the setting of NAFLD could also be attributed to a pre-existing chronic low-grade inflammation associated with surplus and dysfunctional adipose tissue in these individuals. Here we investigate the hypothesis that a pre-existing inflammatory status is exacerbated after severe acute respiratory syndrome coronavirus 2 infection, which embodies a second hit to the underestimated liver damage.

Adipose Tissue Dysfunction: Impact on Metabolic Changes?

Adipose tissue is a metabolically dynamic organ that is the primary site of storage for excess energy, but it serves as an endocrine organ capable of synthesizing a number of biologically active compounds that regulate metabolic homeostasis. However, when the capacity of expansion of this tissue exceeds, dysfunction occurs, favoring ectopic accumulation of fat in the visceral, which has been implicated in several disease states, most notably obesity. This review highlights the mechanisms involved in the structure of adipose tissue, tissue expandability, adipocyte dysfunction, as well as the impact of these events on the manifestation of important metabolic disorders associated with adipose tissue dysfunction. A literature search using Pubmed, Web of Science, Scopus, and Cochrane databases were used to identify relevant studies, using clinical trials, experimental studies in animals and humans, case-control studies, case series, letters to the editor, and review articles published in English, without restrictions on year of publication. The excessive ectopic lipid accumulation leads to local inflammation and insulin resistance. Indeed, overnutrition triggers uncontrolled inflammatory responses white adipose tissue, leading to chronic low-grade inflammation, therefore fostering the progression of important metabolic disorders. Thus, it is essential to advance the understanding of the molecular mechanisms involved in adipose tissue dysfunction in order to mitigate the negative metabolic consequences of obesity.

Hypoxia as a Double-Edged Sword to Combat Obesity and Comorbidities

The global epidemic of obesity is tightly associated with numerous comorbidities, such as type II diabetes, cardiovascular diseases and the metabolic syndrome. Among the key features of obesity, some studies have suggested the abnormal expansion of adipose-tissue-induced local endogenous hypoxic, while other studies indicated endogenous hyperoxia as the opposite trend. Endogenous hypoxic aggravates dysfunction in adipose tissue and stimulates secretion of inflammatory molecules, which contribute to obesity. In contrast, hypoxic exposure combined with training effectively generate exogenous hypoxic to reduce body weight and downregulate metabolic risks. The (patho)physiological effects in adipose tissue are distinct from those of endogenous hypoxic. We critically assess the latest advances on the molecular mediators of endogenous hypoxic that regulate the dysfunction in adipose tissue. Subsequently we propose potential therapeutic targets in adipose tissues and the small molecules that may reverse the detrimental effect of local endogenous hypoxic. More importantly, we discuss alterations of metabolic pathways in adipose tissue and the metabolic benefits brought by hypoxic exercise. In terms of therapeutic intervention, numerous approaches have been developed to treat obesity, nevertheless durability and safety remain the major concern. Thus, a combination of the therapies that suppress endogenous hypoxic with exercise plans that augment exogenous hypoxic may accelerate the development of more effective and durable medications to treat obesity and comorbidities.

Retinochoroidal microvascular changes in newly developed obese children: an optical coherence tomography angiography study

Background

Childhood obesity was associated with retinochoroidal microvascular changes using optical coherence tomography angiography (OCTA), but obesity duration was neglected. Obesity is chronic and progressive and obesity duration is related to microvascular function. Thus, it is important to identify microvascular changes in obese children timely to allow possible interventions with the increase in the number of obese children. This pilot study aimed to characterize retinochoroidal microvascular changes in newly developed obese children compared to age- and sex-matched controls.

Methods

Forty newly developed obese children and 40 age- and sex-matched controls were recruited. All subjects completed comprehensive eye examinations, including axial length, cycloplegic refraction, optical coherence tomography angiography scans (AngioVue; Optovue Inc), etc.

Results

There were no statistically significant differences between groups in terms of month age (P = 0.927), spherical equivalent refraction (P = 0.753) and axial length (P = 0.196). Newly developed obese children had lower vessel density (VD) in the inferior parafovea (P = 0.026), nasal parafovea (P = 0.038) and temporal perifovea (P = 0.026) of deep vascular complex (DVC), higher VD in the fovea of superficial vascular complex (P = 0.021) and the fovea of DVC (P = 0.016), and smaller foveal avascular zone (P = 0.003) when compared to controls. Also, no apparent differences in any quadrant of total retinal thickness, subfoveal choroidal thickness (SFCT), and choriocapillaries fow voids were detected (all P > 0.05).

Conclusion

Retinochoroidal microvascular changes had already occurred in newly developed obese children, so early screening and close follow-up eye examinations were recommended; Retinal microvascular insult may precede its structural change and that retina may be a better candidate to predict the onset of retinochoroidal microvascular changes than choroid in obese children.

Association of dyslipidemia and hypoxemia in patients with obstructive sleep apnea hypopnea syndrome: a cross-sectional study

OBJECTIVE

Studies have shown that dyslipidemia may contribute to chronic tissue hypoxia. However, it remains unclear whether dyslipidemia affects chronic hypoxia in patients with obstructive sleep apnea hypopnea syndrome (OSAHS). Therefore, from a clinical practice perspective, the purpose of this study was to investigate the effect of dyslipidemia on chronic hypoxia in OSAHS patients.

METHOD

In athis cross-sectional survey, 320 consecutive OSAHS patients were enrolled. By screening under different conditions, 211 patients were finally enrolled in the study. Patients were grouped according to apnea-hypopnea index (AHI), into a mild-to-moderate (AHI < 30) group and severe OSAHS group (AHI ≥ 30).

RESULTS

Comparative analysis shows that 45% of mild-to-moderate OSAHS patients had severe hypoxemia. Univariate and multivariate regression analyses showed that AHI, triglycerides (TG), and high-density lipoprotein cholesterol (HDL-C) had independent effects on lowest oxygen saturation (LSpO₂), and that AHI and TG levels had independent effects on mean oxygen saturation (MSpO₂). The patients were stratified by AHI and further grouped by TG and HDL-C abnormalities in each subgroup. A difference analysis showed that LSpO₂ and MSpO₂ were significantly decreased in OSAHS patients with dyslipidemia (high TG and low HDL-C levels) in the AHI ≥ 30 subgroup (P < 0.05). Finally, in order to further clarify the impact of the selected indicators of hypoxemia in OSAHS patients with different degrees of airway obstruction, subgroup analysis was conducted based on OSAHS severity. In the AHI < 30 subgroup, LSpO₂ was significantly decreased in patients with abnormal HDL-C.

CONCLUSION

The results of this study indicate that abnormalities in TG and HDL-C, in addition to upper airway obstruction, are among the factors that aggravate chronic hypoxia in tissues from OSAHS patients.

Physiological Oxygen Levels Differentially Regulate Adipokine Production in Abdominal and Femoral Adipocytes from Individuals with Obesity Versus Normal Weight

Adipose tissue (AT) inflammation may increase obesity-related cardiometabolic complications. Altered AT oxygen partial pressure (pO₂) may impact the adipocyte inflammatory phenotype. Here, we investigated the effects of physiological pO₂ levels on the inflammatory phenotype of abdominal (ABD) and femoral (FEM) adipocytes derived from postmenopausal women with normal weight (NW) or obesity (OB). Biopsies were collected from ABD and FEM subcutaneous AT in eighteen postmenopausal women (aged 50-65 years) with NW (BMI 18-25 kg/m², n = 9) or OB (BMI 30-40 kg/m², n = 9). We compared the effects of prolonged exposure to different physiological pO₂ levels on adipokine expression and secretion in differentiated human multipotent adipose-derived stem cells. Low physiological pO₂ (5% O₂) significantly increased leptin gene expression/secretion in ABD and FEM adipocytes derived from individuals with NW and OB compared with high physiological pO₂ (10% O₂) and standard laboratory conditions (21% O₂). Gene expression/secretion of IL-6, DPP-4, and MCP-1 was reduced in differentiated ABD and FEM adipocytes from individuals with OB but not NW following exposure to low compared with high physiological pO₂ levels. Low physiological pO₂ decreases gene expression and secretion of several proinflammatory factors in ABD and FEM adipocytes derived from individuals with OB but not NW.

Of mice and men: Pinpointing species differences in adipose tissue biology

The prevalence of obesity and metabolic diseases continues to rise, which has led to an increased interest in studying adipose tissue to elucidate underlying disease mechanisms. The use of genetic mouse models has been critical for understanding the role of specific genes for adipose tissue function and the tissue’s impact on other organs. However, mouse adipose tissue displays key differences to human fat, which has led, in some cases, to the emergence of some confounding concepts in the adipose field. Such differences include the depot-specific characteristics of visceral and subcutaneous fat, and divergences in thermogenic fat phenotype between the species. Adipose tissue characteristics may therefore not always be directly compared between species, which is important to consider when setting up new studies or interpreting results. This mini review outlines our current knowledge about the cell biological differences between human and mouse adipocytes and fat depots, highlighting some examples where inadequate knowledge of species-specific differences can lead to confounding results, and presenting plausible anatomic explanations that may underlie the differences. The article thus provides critical insights and guidance for researchers working primarily with only human or mouse fat tissue, and may contribute to new ideas or concepts in the important and evolving field of adipose biology.

Of mice and men: Considerations on adipose tissue physiology in animal models of obesity and human studies

The ever-increasing burden of obesity demands a better pathophysiological understanding, especially regarding adipose tissue pathophysiology. Animal models of obesity are of great importance in investigating potential mechanisms and implications of obesity. Many issues should be considered while interpreting the preclinical results as anatomical and pathophysiological differences exist among species. Importantly, the natural history of obesity development differs considerably. An important example of conflicting results among preclinical models and human physiological studies is that of adipose tissue oxygenation, where rodent models almost unanimously have shown the presence of hypoxia in the adipose tissue of obese animals while human studies have yielded conflicting results to date. Other issues which require further clarification before generalizing preclinical data in humans include adipose tissue browning, endocrine function and fibrosis. The aim of this mini-review is to synopsize similarities and differences between rodent models and humans, which should be taken into consideration in obesity studies.

CYP1A1, VEGFA and Adipokine Responses of Human Adipocytes Co-exposed to PCB126 and Hypoxia

It is increasingly recognized that hypoxia may develop in adipose tissue as its mass expands. Adipose tissue is also the main reservoir of lipophilic pollutants, including polychlorinated biphenyls (PCBs). Both hypoxia and PCBs have been shown to alter adipose tissue functions. The signaling pathways induced by hypoxia and pollutants may crosstalk, as they share a common transcription factor: aryl hydrocarbon receptor nuclear translocator (ARNT). Whether hypoxia and PCBs crosstalk and affect adipokine secretion in human adipocytes remains to be explored. Using primary human adipocytes acutely co-exposed to different levels of hypoxia (24 h) and PCB126 (48 h), we observed that hypoxia significantly inhibits the PCB126 induction of cytochrome P450 (CYP1A1) transcription in a dose-response manner, and that Acriflavine (ACF)—an HIF1α inhibitor—partially restores the PCB126 induction of CYP1A1 under hypoxia. On the other hand, exposure to PCB126 did not affect the transcription of the vascular endothelial growth factor-A (VEGFA) under hypoxia. Exposure to hypoxia increased leptin and interleukin-6 (IL-6), and decreased adiponectin levels dose-dependently, while PCB126 increased IL-6 and IL-8 secretion in a dose-dependent manner. Co-exposure to PCB126 and hypoxia did not alter the adipokine secretion pattern observed under hypoxia and PCB126 exposure alone. In conclusion, our results indicate that (1) hypoxia inhibits PCB126-induced CYP1A1 expression at least partly through ARNT-dependent means, suggesting that hypoxia could affect PCB metabolism and toxicity in adipose tissue, and (2) hypoxia and PCB126 affect leptin, adiponectin, IL-6 and IL-8 secretion differently, with no apparent crosstalk between the two factors.

Angiogenesis in adipose tissue and obesity

While most tissues exhibit their greatest growth during development, adipose tissue is capable of additional massive expansion in adults. Adipose tissue expandability is advantageous when temporarily storing fuel for use during fasting, but becomes pathological upon continuous food intake, leading to obesity and its many comorbidities. The dense vasculature of adipose tissue provides necessary oxygen and nutrients, and supports delivery of fuel to and from adipocytes under fed or fasting conditions. Moreover, the vasculature of adipose tissue comprises a major niche for multipotent progenitor cells, which give rise to new adipocytes and are necessary for tissue repair. Given the multiple, pivotal roles of the adipose tissue vasculature, impairments in angiogenic capacity may underlie obesity-associated diseases such as diabetes and cardiometabolic disease. Exciting new studies on the single-cell and single-nuclei composition of adipose tissues in mouse and humans are providing new insights into mechanisms of adipose tissue angiogenesis. Moreover, new modes of intercellular communication involving micro vesicle and exosome transfer of proteins, nucleic acids and organelles are also being recognized to play key roles. This review focuses on new insights on the cellular and signaling mechanisms underlying adipose tissue angiogenesis, and on their impact on obesity and its pathophysiological consequences.

The Benefits of High-Resistant Starch and Beta-Carotene Snack in Ameliorating Atherogenic Index and Inflammation in Obesity

BACKGROUND: In obesity, lipid abnormalities may be related to the higher risk of cardiovascular diseases associated with increased oxidation of lipids and inflammation. Resistant starch and beta-carotene reduce atherosclerosis risk related to low-grade inflammation and oxidative stress in obesity. AIM: This study aimed to evaluate the benefits of a snack containing high-resistant starch and beta-carotene in improving the atherogenic index of plasma (AIP) and inflammation in obesity. METHODS: This study used a single-blinded and randomized controlled design. Fifty subjects received 42 g of snacks per day for 6 weeks, either tested snacks or standard snacks. Anthropometry, body composition, lipid profile, tumor necrosis factor-alpha (TNF-α), and oxidized low-density lipoprotein (ox-LDL) were measured before and after intervention. RESULTS: The snack containing high-resistant starch and beta-carotene significantly decreased LDL, AIP, and TNF-α (p < 0.05). Positive correlations were found between AIP and triglycerides in both snacks (p < 0.05), LDL or TNF-α in the standard snack (p < 0.05), and TNF-α and ox-LDL in both snacks (p < 0.05). A negative correlation was found between AIP and HDL in both snacks (p < 0.05). CONCLUSIONS: A snack containing high-resistant starch and beta-carotene reduced AIP and inflammation by preventing LDL oxidation.

Genome-wide identification of copy number variation and association with fat deposition in thin and fat-tailed sheep breeds

Copy number variants (CNVs) are a type of genetic polymorphism which contribute to phenotypic variation in several species, including livestock. In this study, we used genomic data of 192 animals from 3 Iranian sheep breeds including 96 Baluchi sheep and 47 Lori-Bakhtiari sheep as fat-tailed breeds and 47 Zel sheep as thin-tailed sheep breed genotyped with Illumina OvineSNP50K Beadchip arrays. Also, for association test, 70 samples of Valle del Belice sheep were added to the association test as thin-tailed sheep breed. PennCNV and CNVRuler software were, respectively, used to study the copy number variation and genomic association analyses. We detected 573 and 242 CNVs in the fat and thin tailed breeds, respectively. In terms of CNV regions (CNVRs), these represented 328 and 187 CNVRs that were within or overlapping with 790 known Ovine genes. The CNVRs covered approximately 73.85 Mb of the sheep genome with average length 146.88 kb, and corresponded to 2.6% of the autosomal genome sequence. Five CNVRs were randomly chosen for validation, of which 4 were experimentally confirmed using Real time qPCR. Functional enrichment analysis showed that genes harbouring CNVs in thin-tailed sheep were involved in the adaptive immune response, regulation of reactive oxygen species biosynthetic process and response to starvation. In fat-tailed breeds these genes were involved in cellular protein modification process, regulation of heart rate, intestinal absorption, olfactory receptor activity and ATP binding. Association test identified one copy gained CNVR on chromosomes 6 harbouring two protein-coding genes HGFAC and LRPAP1. Our findings provide information about genomic structural changes and their association to the interested traits including fat deposition and environmental compatibility in sheep.

A Toolbox to Investigate the Impact of Impaired Oxygen Delivery in Experimental Disease Models

Impaired oxygen utilization is the underlying pathophysiological process in different shock states. Clinically most important are septic and hemorrhagic shock, which comprise more than 75% of all clinical cases of shock. Both forms lead to severe dysfunction of the microcirculation and the mitochondria that can cause or further aggravate tissue damage and inflammation. However, the detailed mechanisms of acute and long-term effects of impaired oxygen utilization are still elusive. Importantly, a defective oxygen exploitation can impact multiple organs simultaneously and organ damage can be aggravated due to intense organ cross-talk or the presence of a systemic inflammatory response. Complexity is further increased through a large heterogeneity in the human population, differences in genetics, age and gender, comorbidities or disease history. To gain a deeper understanding of the principles, mechanisms, interconnections and consequences of impaired oxygen delivery and utilization, interdisciplinary preclinical as well as clinical research is required. In this review, we provide a "tool-box" that covers widely used animal disease models for septic and hemorrhagic shock and methods to determine the structure and function of the microcirculation as well as mitochondrial function. Furthermore, we suggest magnetic resonance imaging as a multimodal imaging platform to noninvasively assess the consequences of impaired oxygen delivery on organ function, cell metabolism, alterations in tissue textures or inflammation. Combining structural and functional analyses of oxygen delivery and utilization in animal models with additional data obtained by multiparametric MRI-based techniques can help to unravel mechanisms underlying immediate effects as well as long-term consequences of impaired oxygen delivery on multiple organs and may narrow the gap between experimental preclinical research and the human patient.

The multifaceted roles of the adipose tissue vasculature

The prevalence of obesity and its associated pathologies continue to increase, which has led to a renewed interest in our major weight-regulating organ, the white adipose tissue. It has become clear that its development, expansion, and physiological function depend on proper crosstalk between each of its cellular constituents, with a central role for the vascular endothelium lining the blood vessels. Although first considered a mere barrier, the endothelium has emerged as a dynamic unit modulating many critical adipose tissue functions. It not only oversees the uptake of all nutrients to be stored in the adipocytes but also provides an important growth niche for adipocyte progenitors and regulates the expandability of the tissue during overfeeding and obesity. In this review, we describe the reciprocal relationship between endothelial cells, adipocytes, and obesity. We present recent studies that support an important role for endothelial cells as central mediators of many of the physiological and pathological functions of the adipose tissue and highlight several unknown aspects of adipose tissue vascular biology. This new perspective could present exciting opportunities to develop new therapeutic approaches against obesity-related pathologies and is thus of great interest in our increasingly obese society.

Changes in mechanical properties of adipose tissue after bariatric surgery driven by extracellular matrix remodelling and neovascularization are associated with metabolic improvements

Biomechanical properties of adipose tissue (AT) are closely involved in the development of obesity-associated comorbidities. Bariatric surgery (BS) constitutes the most effective option for a sustained weight loss in addition to improving obesity-associated metabolic diseases including type 2 diabetes (T2D). We aimed to determine the impact of weight loss achieved by BS and caloric restriction (CR) on the biomechanical properties of AT. BS but not CR changed the biomechanical properties of epididymal white AT (EWAT) from a diet-induced obesity rat model, which were associated with metabolic improvements. We found decreased gene expression levels of collagens and Lox together with increased elastin and Mmps mRNA levels in EWAT after BS, which were also associated with the biomechanical properties. Moreover, an increased blood vessel density was observed in EWAT after surgery, confirmed by an upregulation of Acta2 and Antxr1 gene expression levels, which was also correlated with the biomechanical properties. Visceral AT from patients with obesity showed increased stiffness after tensile tests compared to the EWAT from the animal model. This study uncovers new insights into EWAT adaptation after BS with decreased collagen crosslink and synthesis as well as an increased degradation together with enhanced blood vessel density providing, simultaneously, higher stiffness and more ductility. STATEMENT OF SIGNIFICANCE: Biomechanical properties of the adipose tissue (AT) are closely involved in the development of obesity-associated comorbidities. In this study, we show for the first time that biomechanical properties of AT determined by E, UTS and strain at UTS are decreased in obesity, being increased after bariatric surgery by the promotion of ECM remodelling and neovascularization. Moreover, these changes in biomechanical properties are associated with improvements in metabolic homeostasis. Consistently, a better characterization of the plasticity and biomechanical properties of the AT after bariatric surgery opens up a new field for the development of innovative strategies for the reduction of fibrosis and inflammation in AT as well as to better understand obesity and its associated comorbidities.

The Effects of Mild Intermittent Hypoxia Exposure on the Abdominal Subcutaneous Adipose Tissue Proteome in Overweight and Obese Men: A First-in-Human Randomized, Single-Blind, and Cross-Over Study

Adipose tissue (AT) oxygen tension (pO₂) has been implicated in AT dysfunction and metabolic perturbations in both rodents and humans. Compelling evidence suggests that hypoxia exposure alters metabolism, at least partly through effects on AT. However, it remains to be elucidated whether mild intermittent hypoxia (MIH) exposure impacts the AT proteome. We performed a randomized, single-blind, and cross-over study to investigate the effects of seven consecutive days of MIH (FiO₂ 15%, 3x2h/d) compared to normoxia (FiO₂ 21%) exposure on the AT proteome in overweight/obese men. In vivo AT insulin sensitivity was determined by the gold standard hyperinsulinemic-euglycemic clamp, and abdominal subcutaneous AT biopsies were collected under normoxic fasting conditions following both exposure regimens (day 8). AT proteins were isolated and quantified using liquid chromatography-mass spectrometry. After correction for blood contamination, 1,022 AT protein IDs were identified, of which 123 were differentially expressed following MIH (p < 0.05). We demonstrate for the first time that MIH exposure, which markedly reduces in vivo AT oxygen tension, impacts the human AT proteome. Although we cannot exclude that a single differentially expressed protein might be a false positive finding, several functional pathways were altered by MIH exposure, also after adjustment for multiple testing. Specifically, differentially expressed proteins were involved in redox systems, cell-adhesion, actin cytoskeleton organization, extracellular matrix composition, and energy metabolism. The MIH-induced change in AT TMOD3 expression was strongly related to altered in vivo AT insulin sensitivity, thus linking MIH-induced effects on the AT proteome to metabolic changes in overweight/obese humans.

Effects of Obesity on Infections with Emphasis on Skin Infections and Wound Healing

Obesity represents a serious health problem as it is rapidly increasing worldwide. Obesity is associated with reduced health span and life span, decreased responses to infections and vaccination and increased frequency of inflammatory conditions. In this review, we summarize published data showing that obesity increases the risk of different types of infections, with a special focus on skin infections. Obesity also induces skin changes and conditions (inflammation-based and hypertrophic) which are often associated with fungi or bacteria overgrowth. The association of obesity with the skin microbiome has been established in both mice and humans. Balance of commensal microbes controls skin homeostasis and the host immune response, while changes in normal physiologic skin microbiome composition and pathologic bacteria contribute to skin diseases. We also summarize the major steps in wound healing and how obesity affects each of them. The role that immune cells have in this process is also described. Although the studies summarized in this review clearly demonstrate the deleterious effects of obesity on wound healing, additional studies are needed to better characterize the cellular and molecular mechanisms involved and identify specific targets of intervention.

On the Immunometabolic Role of NF-κB in Adipocytes

Two decades of research have established that Nuclear Factor-κB (NF-κB) signaling plays a critical role in reprogramming the fat cell transcriptome towards inflammation in response to overnutrition and metabolic stress. Several groups have suggested that inhibition of NF-κB signaling could have metabolic benefits for obesity-associated adipose tissue inflammation. However, two significant problems arise with this approach. The first is how to deliver general NF-κB inhibitors into adipocytes without allowing these compounds to disrupt normal functioning in cells of the immune system. The second issue is that general inhibition of canonical NF-κB signaling in adipocytes will likely lead to a massive increase in adipocyte apoptosis under conditions of metabolic stress, leading full circle into a secondary inflammation (However, this problem may not be true for non-canonical NF-κB signaling.). This review will focus on the research that has examined canonical and non-canonical NF-κB signaling in adipocytes, focusing on genetic studies that examine loss-of-function of NF-κB specifically in fat cells. Although the development of general inhibitors of canonical NF-κB signaling seems unlikely to succeed in alleviating adipose tissue inflammation in humans, the door remains open for more targeted therapeutics. In principle, these would include compounds that interrogate NF-κB DNA binding, protein-protein interactions, or post-translational modifications that partition NF-κB activity towards some genes and away from others in adipocytes. I also discuss the possibility for inhibitors of non-canonical NF-κB signaling to realize success in mitigating fat cell dysfunction in obesity. To plant the seeds for such approaches, much biochemical “digging” in adipocytes remains; this includes identifying—in an unbiased manner–NF-κB direct and indirect targets, genomic DNA binding sites for all five NF-κB subunits, NF-κB protein-protein interactions, and post-translational modifications of NF-κB in fat cells.

An Exploratory Analysis of the Role of Adipose Characteristics in Fulltime Wheelchair Users' Pressure Injury History

Aim: The goals of this study were 1) to identify the relationship between adipose (subcutaneous and intramuscular) characteristics and pressure injury (PrI) history in wheelchair users and 2) to identify subject characteristics, including biomechanical risk, that are related to adipose characteristics. Materials and Methods: The buttocks of 43 full-time wheelchair users with and without a history of pelvic PrIs were scanned in a seated posture in a FONAR UPRIGHT® MRI. Intramuscular adipose (the relative difference in intensity between adipose and gluteus maximus) and the subcutaneous adipose characteristics (the relative difference in intensity between subcutaneous adipose under and surrounding the ischium) were compared to PrI history and subject characteristics. Results: Participants with a history of PrIs had different subcutaneous fat (subQF) characteristics than participants without a history of PrIs. Specifically, they had significantly darker adipose under the ischium than surrounding the ischium (subQF effect size = 0.21) than participants without a history of PrIs (subQF effect size = 0.58). On the other hand, only when individuals with complete fat infiltration (n = 7) were excluded did individuals with PrI history have more fat infiltration than those without a PrI history. The presence of spasms (μ intramuscular adipose, 95% CI with spasms 0.642 [0.430, 0.855], without spasms 0.168 [-0.116, 0.452], p = 0.01) and fewer years using a wheelchair were associated with leaner muscle (Pearson Corr = -0.442, p = 0.003). Conclusion: The results of the study suggest the hypothesis that changes in adipose tissue under the ischial tuberosity (presenting as darker SubQF) are associated with increased biomechanical risk for pressure injury. Further investigation of this hypothesis, and the role of intramuscular fat infiltration in PrI development, may help our understanding of PrI etiology. It may also lead to clinically useful diagnostic techniques that can identify changes in adipose and biomechanical risk to inform early preventative interventions.

Inflammation in Coronary Microvascular Dysfunction

Chronic low-grade inflammation is involved in coronary atherosclerosis, presenting multiple clinical manifestations ranging from asymptomatic to stable angina, acute coronary syndrome, heart failure and sudden cardiac death. Coronary microvasculature consists of vessels with a diameter less than 500 μm, whose potential structural and functional abnormalities can lead to inappropriate dilatation and an inability to meet the required myocardium oxygen demands. This review focuses on the pathogenesis of coronary microvascular dysfunction and the capability of non-invasive screening methods to detect the phenomenon. Anti-inflammatory agents, such as statins and immunomodulators, including anakinra, tocilizumab, and tumor necrosis factor-alpha inhibitors, have been assessed recently and may constitute additional or alternative treatment approaches to reduce cardiovascular events in atherosclerotic heart disease characterized by coronary microvascular dysfunction.

Measurement of human abdominal and femoral intravascular adipose tissue blood flow using percutaneous Doppler ultrasound

Adipose tissue blood flow (ATBF) is an important determinant of adipose tissue (AT) function. ¹³³Xenon wash-out technique is considered the gold-standard for human ATBF measurements. However, decreasing ¹³³Xenon clinical use and costly production and preservation, make alternative (non-invasive) methods necessary. Here, we explored percutaneous Doppler ultrasound as a proxy method to quantify intravascular subcutaneous abdominal and femoral ATBF in humans (n= 17). Both fasting ATBF and the postprandial increase in ATBF were significantly higher in abdominal compared to femoral AT. Although anatomical variations in vein location and depot thickness may impact feasibility, we demonstrate that Doppler ultrasound detects the expected depot-differences and postprandial increase in ATBF in healthy individuals. This method warrants further investigation in other populations and metabolic conditions.

Meta-Inflammation and Metabolic Reprogramming of Macrophages in Diabetes and Obesity: The Importance of Metabolites

Diabetes mellitus type II and obesity are two important causes of death in modern society. They are characterized by low-grade chronic inflammation and metabolic dysfunction (meta-inflammation), which is observed in all tissues involved in energy homeostasis. A substantial body of evidence has established an important role for macrophages in these tissues during the development of diabetes mellitus type II and obesity. Macrophages can activate into specialized subsets by cues from their microenvironment to handle a variety of tasks. Many different subsets have been described and in diabetes/obesity literature two main classifications are widely used that are also defined by differential metabolic reprogramming taking place to fuel their main functions. Classically activated, pro-inflammatory macrophages (often referred to as M1) favor glycolysis, produce lactate instead of metabolizing pyruvate to acetyl-CoA, and have a tricarboxylic acid cycle that is interrupted at two points. Alternatively activated macrophages (often referred to as M2) mainly use beta-oxidation of fatty acids and oxidative phosphorylation to create energy-rich molecules such as ATP and are involved in tissue repair and downregulation of inflammation. Since diabetes type II and obesity are characterized by metabolic alterations at the organism level, these alterations may also induce changes in macrophage metabolism resulting in unique macrophage activation patterns in diabetes and obesity. This review describes the interactions between metabolic reprogramming of macrophages and conditions of metabolic dysfunction like diabetes and obesity. We also focus on different possibilities of measuring a range of metabolites intra-and extracellularly in a precise and comprehensive manner to better identify the subsets of polarized macrophages that are unique to diabetes and obesity. Advantages and disadvantages of the currently most widely used metabolite analysis approaches are highlighted. We further describe how their combined use may serve to provide a comprehensive overview of the metabolic changes that take place intracellularly during macrophage activation in conditions like diabetes and obesity.

Subcutaneous Adipose Tissue Metabolic Function and Insulin Sensitivity in People With Obesity

We used stable isotope-labeled glucose and palmitate tracer infusions, a hyperinsulinemic-euglycemic clamp, positron emission tomography of muscles and adipose tissue after [18F]fluorodeoxyglucose and [15O]water injections, and subcutaneous adipose tissue (SAT) biopsy to test the hypotheses that 1) increased glucose uptake in SAT is responsible for high insulin-stimulated whole-body glucose uptake in people with obesity who are insulin sensitive and 2) putative SAT factors thought to cause insulin resistance are present in people with obesity who are insulin resistant but not in those who are insulin sensitive. We found that high insulin-stimulated whole-body glucose uptake in insulin-sensitive participants with obesity was not due to channeling of glucose into SAT but, rather, was due to high insulin-stimulated muscle glucose uptake. Furthermore, insulin-stimulated muscle glucose uptake was not different between insulin-sensitive obese and lean participants even though adipocytes were larger, SAT perfusion and oxygenation were lower, and markers of SAT inflammation, fatty acid appearance in plasma in relation to fat-free mass, and plasma fatty acid concentration were higher in the insulin-sensitive obese than in lean participants. In addition, we observed only marginal or no differences in adipocyte size, SAT perfusion and oxygenation, and markers of SAT inflammation between insulin-resistant and insulin-sensitive obese participants. Plasma fatty acid concentration was also not different between insulin-sensitive and insulin-resistant obese participants, even though SAT was resistant to the inhibitory effect of insulin on lipolysis in the insulin-resistant obese group. These data suggest that several putative SAT factors commonly implicated in causing insulin resistance are normal consequences of SAT expansion unrelated to insulin resistance.

Oxygen in Metabolic Dysfunction and Its Therapeutic Relevance

Significance: In recent years, a number of studies have shown altered oxygen partial pressure at a tissue level in metabolic disorders, and some researchers have considered oxygen to be a (macro) nutrient. Oxygen availability may be compromised in obesity and several other metabolism-related pathological conditions, including sleep apnea-hypopnea syndrome, the metabolic syndrome (which is a set of conditions), type 2 diabetes, cardiovascular disease, and cancer. Recent Advances: Strategies designed to reduce adiposity and its accompanying disorders have been mainly centered on nutritional interventions and physical activity programs. However, novel therapies are needed since these approaches have not been sufficient to counteract the worldwide increasing rates of metabolic disorders. In this regard, intermittent hypoxia training and hyperoxia could be potential treatments through oxygen-related adaptations. Moreover, living at a high altitude may have a protective effect against the development of abnormal metabolic conditions. In addition, oxygen delivery systems may be of therapeutic value for supplying the tissue-specific oxygen requirements. Critical Issues: Precise in vivo methods to measure oxygenation are vital to disentangle some of the controversies related to this research area. Further, it is evident that there is a growing need for novel in vitro models to study the potential pathways involved in metabolic dysfunction to find appropriate therapeutic targets. Future Directions: Based on the existing evidence, it is suggested that oxygen availability has a key role in obesity and its related comorbidities. Oxygen should be considered in relation to potential therapeutic strategies in the treatment and prevention of metabolic disorders. Antioxid. Redox Signal. 35, 642-687.

Fat biology and metabolic balance: On the significance of sex

Obesity and its related metabolic disorders have become prevalent and fatal, which are faced by the entire human beings since decades. An energy equilibrium is urgently important for human metabolic health, which requires the participation of multiple organs, such as adipose tissues, liver and skeletal muscles. It seems that both sex and age play a role in the above processes. In this review, we focus on the sexual dimorphism in energy metabolism mediated by adipose tissues, including white and thermogenic (brown/beige) adipose tissues. Remarkably, past investigations have focused on targeting brown/beige adipose tissues to combat obesity because of their contributions to non-shivering thermogenesis. However, sex differences in the regulation of adipose tissue metabolism are likely overlooked. Particularly, increasing data show that males display more visceral fat than females, and females show increased visceral fat after menopause. Visceral adiposity is more deleterious and closely related to metabolic disorders, such as cardiovascular diseases. In this review, we discuss current findings on sexual dimorphism in WAT and BAT biology for a better metabolic balance in humans.