From blood monocytes to adipose tissue-resident macrophages: induction of diapedesis by human mature adipocytes

Tissue-Level Effect of Andrographis and Ashwagandha Metabolites on Metabolic and Inflammatory Gene Expression in Skeletal Muscle and Adipose Tissue: An Ex Vivo/In Vitro Investigation

Adipose tissue and skeletal muscle dysfunction play a central role in cardiometabolic morbidity. Ashwagandha and Andrographis are purported to have anti-inflammatory and antioxidant activity, but this is based on exposure of cells to the parent compounds ignoring phytochemical absorption and metabolism. We explored the anti-inflammatory/antioxidant effects of ashwagandha and Andrographis in ex vivo human models of skeletal muscle and adipose tissue. Healthy participants supplemented with 2000 mg/day Andrographis (n = 10) or 1100 mg/day ashwagandha (n = 10) for 28 days. Sera collected pre (D0) and post (D28) supplementation were pooled by timepoint and added to adipose explant (AT) and primary human myotube (SKMC) culture media (15% v/v) for treatment. A Taqman panel of 56 genes was used to quantify these. In AT, treatment with ashwagandha sera decreased the expression of genes involved in antioxidant defence and inflammatory response (CCL5, CD36, IL6, IL10, ADIPOQ, NFEL2, UCP2, GPX3, GPX4; geometric 95% CI for fold change > 1) and altered the expression of genes involved in fatty acid metabolism. In SKMC, ashwagandha sera altered FOXO1 and SREBF1 expression. Andrographis sera decreased IL18 and SERPINEA3 expression in AT. This physiologically relevant in vitro screening characterises the effects of ashwagandha in AT to guide future clinical trials.

Unraveling the complex roles of macrophages in obese adipose tissue: an overview

Macrophages, a heterogeneous population of innate immune cells, exhibit remarkable plasticity and play pivotal roles in coordinating immune responses and maintaining tissue homeostasis within the context of metabolic diseases. The activation of inflammatory macrophages in obese adipose tissue leads to detrimental effects, inducing insulin resistance through increased inflammation, impaired thermogenesis, and adipose tissue fibrosis. Meanwhile, adipose tissue macrophages also play a beneficial role in maintaining adipose tissue homeostasis by regulating angiogenesis, facilitating the clearance of dead adipocytes, and promoting mitochondrial transfer. Exploring the heterogeneity of macrophages in obese adipose tissue is crucial for unraveling the pathogenesis of obesity and holds significant potential for targeted therapeutic interventions. Recently, the dual effects and some potential regulatory mechanisms of macrophages in adipose tissue have been elucidated using single-cell technology. In this review, we present a comprehensive overview of the intricate activation mechanisms and diverse functions of macrophages in adipose tissue during obesity, as well as explore the potential of drug delivery systems targeting macrophages, aiming to enhance the understanding of current regulatory mechanisms that may be potentially targeted for treating obesity or metabolic diseases.

Nonlinear associations between computed tomography-measures of adiposity and long pentraxin-3 in the Multi-Ethnic Study of Atherosclerosis

Objective

Long pentraxin-3 (PTX-3) is an acute phase protein associated with cardiovascular disease, lung injury, and mortality. We evaluated the association between computed tomography (CT)-measurements of adipose tissue and plasma levels of PTX-3.

Methods

We performed a cross-sectional analysis of community-dwelling adults enrolled in the multi-center Multiethnic Study of Atherosclerosis who underwent cardiac or abdominal CT and had available PTX-3 measurements.

Results

There was a U-shaped association between pericardial adipose tissue volume (PAT), abdominal visceral adipose tissue area (VAT), hepatic attenuation, and PTX-3 levels, with extremes of adiposity associated with greater PTX-3 levels. Using multivariable-adjusted piecewise regression models, among participants with low PAT, every 1% increase in PAT volume was associated with a 13.8% decrease in PTX-3 (95% confidence interval [CI] -21.6 to -6.0); among participants with high PAT, every 1% increase in PAT volume was associated with a 6.0% increase in PTX-3 (95% CI -0.4 to 12.5). Results were similar for abdominal VAT and hepatic attenuation.

Conclusions

In a cohort of community-dwelling adults, we demonstrated a "U-shaped" association between pericardial, abdominal visceral, and hepatic adiposity with PTX3 levels, suggesting that extreme adiposity is associated with greater circulating levels of PTX3. Further work is required to identify the mechanisms linking adiposity and PTX-3.

Zinc homeostasis and redox alterations in obesity

Impairment of both cellular zinc and redox homeostasis is a feature of several chronic diseases, including obesity. A significant two-way interaction exists between redox metabolism and the relatively redox-inert zinc ion. Redox metabolism critically influences zinc homeostasis and controls its cellular availability for various cellular functions by regulating zinc exchange from/to zinc-binding proteins. Zinc can regulate redox metabolism and exhibits multiple pro-antioxidant properties. On the other hand, even minor disturbances in zinc status and zinc homeostasis affect systemic and cellular redox homeostasis. At the cellular level, zinc homeostasis is regulated by a multi-layered machinery consisting of zinc-binding molecules, zinc sensors, and two selective families of zinc transporters, the Zinc Transporter (ZnT) and Zrt, Irt-like protein (ZIP). In the present review, we summarize the current state of knowledge on the role of the mutual interaction between zinc and redox homeostasis in physiology and pathophysiology, pointing to the role of zinc in the alterations responsible for redox stress in obesity. Since zinc transporters primarily control zinc homeostasis, we describe how changes in the expression and activity of these zinc-regulating proteins are associated with obesity.

Decades Long Involvement of THP-1 Cells as a Model for Macrophage Research: A Comprehensive Review

Over the years, researchers have endeavored to identify dependable and reproducible in vitro models for examining macrophage behavior under controlled conditions. The THP-1 cell line has become a significant and widely employed tool in macrophage research within these models. Originating from the peripheral blood of individuals with acute monocytic leukemia, this human monocytic cell line can undergo transformation into macrophage-like cells, closely mirroring primary human macrophages when exposed to stimulants. Macrophages play a vital role in the innate immune system, actively regulating inflammation, responding to infections, and maintaining tissue homeostasis. A comprehensive understanding of macrophage biology and function is crucial for gaining insights into immunological responses, tissue healing, and the pathogenesis of diseases such as viral infections, autoimmune disorders, and neoplastic conditions. This review aims to thoroughly evaluate and emphasize the extensive history of THP-1 cells as a model for macrophage research. Additionally, it will delve into the significance of THP-1 cells in advancing our comprehension of macrophage biology and their invaluable contributions to diverse scientific domains.

Obesity-induced changes in gene expression in feline adipose and skeletal muscle tissue

Indoor-confined cats are prone to developing obesity due to a sedentary life and an energy intake exceeding energy requirements. As in humans, feline obesity decreases insulin sensitivity and increases the risk of developing feline diabetes mellitus, but the pathophysiological mechanisms are currently poorly understood. Human obesity-related metabolic alterations seem to relate to changes in the expression of genes involved in glucose metabolism, insulin action and inflammation. The objective of the current study was to investigate changes in the expression of genes relating to obesity, glucose metabolism and inflammation in cats with non-experimentally induced obesity. Biopsies from the sartorius muscle and subcutaneous adipose tissue were obtained from 73 healthy, neutered, indoor-confined domestic shorthaired cats ranging from lean to obese. Quantification of obesity-related gene expression levels relative to glyceraldehyde-3-phosphate dehydrogenase was performed by quantitative real-time polymerase chain reaction. A negative association between obesity and adiponectin expression was observed in the adipose tissue (mean ± SD; normal weight, 27.30 × 10-3  ± 77.14 × 10-3 ; overweight, 2.89 × 10-3  ± 0.38 × 10-3 and obese, 2.93 × 10-3  ± 4.20 × 10-3 , p < 0.05). In muscle, the expression of peroxisome proliferative activated receptor-γ2 and plasminogen activator inhibitor-1 was increased in the obese compared to the normal-weight cats, and resistin was increased in the normal-weight compared to the overweight cats. There were no detectable obesity-related changes in the messenger RNA levels of inflammatory cytokines. In conclusion, a possible obesity-related low-grade inflammation caused by increased expression of key proinflammatory regulators was not observed. This could imply that the development of feline obesity and ensuing insulin resistance may not be based on tissue-derived inflammation, but caused by several determining factors, many of which still need further investigation.

Herbal medicine for the treatment of obesity-associated asthma: a comprehensive review

Obesity is fast growing as a global pandemic and is associated with numerous comorbidities like cardiovascular disease, hypertension, diabetes, gastroesophageal reflux disease, sleep disorders, nephropathy, neuropathy, as well as asthma. Studies stated that obese asthmatic subjects suffer from an increased risk of asthma, and encounter severe symptoms due to a number of pathophysiology. It is very vital to understand the copious relationship between obesity and asthma, however, a clear and pinpoint pathogenesis underlying the association between obesity and asthma is scarce. There is a plethora of obesity-asthma etiologies reported viz., increased circulating pro-inflammatory adipokines like leptin, resistin, and decreased anti-inflammatory adipokines like adiponectin, depletion of ROS controller Nrf2/HO-1 axis, nucleotide-binding domain, leucine-rich-containing family, pyrin domain-containing-3 (NLRP3) associated macrophage polarization, hypertrophy of WAT, activation of Notch signaling pathway, and dysregulated melanocortin pathway reported, however, there is a very limited number of reports that interrelates these pathophysiologies. Due to the underlying complex pathophysiologies exaggerated by obese conditions, obese asthmatics respond poorly to anti-asthmatic drugs. The poor response towards anti-asthmatic drugs may be due to the anti-asthmatics approach only that ignores the anti-obesity target. So, aiming only at the conventional anti-asthmatic targets in obese-asthmatics may prove to be futile until and unless treatment is directed towards ameliorating obesity pathogenesis for a holistic approach towards amelioration of obesity-associated asthma. Herbal medicines for obesity as well as obesity-associated comorbidities are fast becoming safer and more effective alternatives to conventional drugs due to their multitargeted approach with fewer adverse effects. Although, herbal medicines are widely used for obesity-associated comorbidities, however, a limited number of herbal medicines have been scientifically validated and reported against obesity-associated asthma. Notable among them are quercetin, curcumin, geraniol, resveratrol, β-Caryophyllene, celastrol, tomatidine to name a few. In view of this, there is a dire need for a comprehensive review that may summarize the role of bioactive phytoconstituents from different sources like plants, marine as well as essential oils in terms of their therapeutic mechanisms. So, this review aims to critically discuss the therapeutic role of herbal medicine in the form of bioactive phytoconstituents against obesity-associated asthma available in the scientific literature to date.

Adipose tissue macrophages as potential targets for obesity and metabolic diseases

Macrophage infiltration into adipose tissue is a key pathological factor inducing adipose tissue dysfunction and contributing to obesity-induced inflammation and metabolic disorders. In this review, we aim to present the most recent research on macrophage heterogeneity in adipose tissue, with a focus on the molecular targets applied to macrophages as potential therapeutics for metabolic diseases. We begin by discussing the recruitment of macrophages and their roles in adipose tissue. While resident adipose tissue macrophages display an anti-inflammatory phenotype and promote the development of metabolically favorable beige adipose tissue, an increase in pro-inflammatory macrophages in adipose tissue has negative effects on adipose tissue function, including inhibition of adipogenesis, promotion of inflammation, insulin resistance, and fibrosis. Then, we presented the identities of the newly discovered adipose tissue macrophage subtypes (e.g. metabolically activated macrophages, CD9+ macrophages, lipid-associated macrophages, DARC+ macrophages, and MFehi macrophages), the majority of which are located in crown-like structures within adipose tissue during obesity. Finally, we discussed macrophage-targeting strategies to ameliorate obesity-related inflammation and metabolic abnormalities, with a focus on transcriptional factors such as PPARγ, KLF4, NFATc3, and HoxA5, which promote macrophage anti-inflammatory M2 polarization, as well as TLR4/NF-κB-mediated inflammatory pathways that activate pro-inflammatory M1 macrophages. In addition, a number of intracellular metabolic pathways closely associated with glucose metabolism, oxidative stress, nutrient sensing, and circadian clock regulation were examined. Understanding the complexities of macrophage plasticity and functionality may open up new avenues for the development of macrophage-based treatments for obesity and other metabolic diseases.

A novel 3D culture model for human primary mammary adipocytes to study their metabolic crosstalk with breast cancer in lean and obese conditions

Obesity is a negative prognosis factor for breast cancer. Yet, the biological mechanisms underlying this effect are still largely unknown. An emerging hypothesis is that the transfer of free fatty acids (FFA) between adipocytes and tumor cells might be altered under obese conditions, contributing to tumor progression. Currently there is a paucity of models to study human mammary adipocytes (M-Ads)-cancer crosstalk. As for other types of isolated white adipocytes, herein, we showed that human M-Ads die within 2-3 days by necrosis when grown in 2D. As an alternative, M-Ads were grown in a fibrin matrix, a 3D model that preserve their distribution, integrity and metabolic function for up to 5 days at physiological glucose concentrations (5 mM). Higher glucose concentrations frequently used in in vitro models promote lipogenesis during M-Ads culture, impairing their lipolytic function. Using transwell inserts, the matrix embedded adipocytes were cocultured with breast cancer cells. FFA transfer between M-Ads and cancer cells was observed, and this event was amplified by obesity. Together these data show that our 3D model is a new tool for studying the effect of M-Ads on tumor cells and beyond with all the components of the tumor microenvironment including the immune cells.

Omega-3-Supplemented Fat Diet Drives Immune Metabolic Response in Visceral Adipose Tissue by Modulating Gut Microbiota in a Mouse Model of Obesity

Obesity is a chronic, relapsing, and multifactorial disease characterized by excessive accumulation of adipose tissue (AT), and is associated with inflammation mainly in white adipose tissue (WAT) and an increase in pro-inflammatory M1 macrophages and other immune cells. This milieu favors the secretion of cytokines and adipokines, contributing to AT dysfunction (ATD) and metabolic dysregulation. Numerous articles link specific changes in the gut microbiota (GM) to the development of obesity and its associated disorders, highlighting the role of diet, particularly fatty acid composition, in modulating the taxonomic profile. The aim of this study was to analyze the effect of a medium-fat-content diet (11%) supplemented with omega-3 fatty acids (D2) on the development of obesity, and on the composition of the GM compared with a control diet with a low fat content (4%) (D1) over a 6-month period. The effect of omega-3 supplementation on metabolic parameters and the modulation of the immunological microenvironment in visceral adipose tissue (VAT) was also evaluated. Six-weeks-old mice were adapted for two weeks and then divided into two groups of eight mice each: a control group D1 and the experimental group D2. Their body weight was recorded at 0, 4, 12, and 24 weeks post-differential feeding and stool samples were simultaneously collected to determine the GM composition. Four mice per group were sacrificed on week 24 and their VAT was taken to determine the immune cells phenotypes (M1 or M2 macrophages) and inflammatory biomarkers. Blood samples were used to determine the glucose, total LDL and HDL cholesterol LDL, HDL and total cholesterol, triglycerides, liver enzymes, leptin, and adiponectin. Body weight measurement showed significant differences at 4 (D1 = 32.0 ± 2.0 g vs. D2 = 36.2 ± 4.5 g, p-value = 0.0339), 12 (D1 = 35.7 ± 4.1 g vs. D2 = 45.3 ± 4.9 g, p-value = 0.0009), and 24 weeks (D1 = 37.5 ± 4.7 g vs. D2 = 47.9 ± 4.7, p-value = 0.0009). The effects of diet on the GM composition changed over time: in the first 12 weeks, α and β diversity differed considerably according to diet and weight increase. In contrast, at 24 weeks, the composition, although still different between groups D1 and D2, showed changes compared with previous samples, suggesting the beneficial effects of omega-3 fatty acids in D2. With regard to metabolic analysis, the results did not reveal relevant changes in biomarkers in accordance with AT studies showing an anti-inflammatory environment and conserved structure and function, which is in contrast to reported findings for pathogenic obesity. In conclusion, the results suggest that the constant and sustained administration of omega-3 fatty acids induced specific changes in GM composition, mainly with increases in Lactobacillus and Ligilactobacillus species, which, in turn, modulated the immune metabolic response of AT in this mouse model of obesity.

Inactivity and obesity: consequences for macrophage-mediated inflammation and the development of cardiometabolic disease

Obesity and dyslipidaemia are strongly associated with the development of cardiometabolic diseases including CVD, stroke, type 2 diabetes, insulin resistance and non-alcoholic fatty liver disease. While these conditions are preventable, they are leading causes of mortality globally. There is now overwhelming clinical and experimental evidence that these conditions are driven by chronic systemic inflammation, with a growing body of data suggesting that this can be regulated by increasing levels of physical activity and reducing sedentary time. In this review we address the role of macrophage-mediated inflammation on the development of cardiometabolic diseases in individuals with overweight and obesity and how reducing sedentary behaviour and increasing physical activity appears to lessen these pro-inflammatory processes, reducing the risk of developing cardiometabolic diseases. While loss of subcutaneous and visceral fat mass is important for reducing chronic systemic inflammation, the mediating effects of increasing physical activity levels and lowering sedentary time on the development of inflamed adipose tissue also occur independently of changes in adiposity. The message that weight loss is not necessary for the benefits of physical activity in lowering chronic inflammation and improving health should encourage those for whom losing weight is difficult. Additionally, while the health benefits of meeting the recommended physical activity guidelines are clear, simply moving more appears to lower chronic systemic inflammation. Reducing sitting time and increasing light physical activity may therefore provide an alternative, more approachable manner for some with overweight and obesity to become more active, reduce chronic inflammation and improve cardiometabolic health.

Mudaliar S, A. Phillips S, R. Henry R. Adipose tissue from subjects with type 2 diabetes exhibits impaired capillary formation in response to GROα: involvement of MMPs-2 and -9

Type 2 Diabetes (T2D) is associated with impaired vascularization of adipose tissue (AT) . IL8, GROα and IL15 are pro-angiogenic myokines, secreted at elevated levels by T2D myotubes. We explored the direct impact of these myokines on AT vascularization. AT explants from subjects with T2D and without diabetes (non-diabetic, ND) were treated with rIL8, rGROα and rIL15 in concentrations equal to those in conditioned media (CM) from T2D and ND myotubes, and sprout formation evaluated. Endothelial cells (EC) were isolated from T2D and ND-AT, treated with rGROα and tube formation evaluated. Finally, we investigated the involvement of MMP-2 and -9 in vascularization. ND and T2D concentrations of IL8 or IL15   caused similar stimulation of sprout formation in ND- and T2D-AT. GROα exerted a similar effect in ND-AT. When T2D-AT explants were exposed to GROα, sprout formation in response to T2D concentrations was reduced compared to ND. Exposure of EC from T2D-AT to GROα at T2D concentrations resulted in reduced tube formation. Reduced responses to GROα in T2D-AT and EC were also seen for secretion of MMP-2 and -9. The data indicate that skeletal muscle can potentially regulate AT vascularization, with T2D-AT having impairments in sensitivity to GROα, while responding normally to IL8 and IL15.

Injectable Prevascularized Mature Adipose Tissues (iPAT) to Achieve Long-Term Survival in Soft Tissue Regeneration

Soft tissue regeneration remains a challenge in reconstructive surgery. So far, both autologous fat implantations and artificial implants methods used in clinical applications lead to various disadvantages and limited lifespan. To overcome these limitations and improve the graft volume maintenance, reproducing a mature adipose tissue already including vasculature structure before implantation can be the solution. Therefore, injectable prevascularized adipose tissues (iPAT) are made from physiological collagen microfibers mixed with human mature adipocytes, adipose-derived stem cells, and human umbilical vein endothelial cells, embedded in fibrin gel. Following murine subcutaneous implantation, the iPAT show a higher cell survival (84% ± 6% viability) and volume maintenance after 3 months (up to twice heavier) when compared to non-prevascularized balls and liposuctioned fat implanted controls. This higher survival can be explained by the greater amount of blood vessels found (up to 1.6-fold increase), with balanced host anastomosis (51% ± 1% of human/mouse lumens), also involving infiltration by the lymphatic and neural vasculature networks. Furthermore, with the cryopreservation possibility enabling their later reinjection, the iPAT technology has the merit to allow noninvasive soft tissue regeneration for long-term outcomes.

Aberrant Mesenteric Adipose Extracellular Matrix Remodelling is Involved in Adipocyte Dysfunction in Crohn's Disease: The Role of TLR-4-mediated Macrophages

BACKGROUND AND AIMS

Hypertrophic mesenteric adipose tissue [htMAT] is involved in the disease progression of Crohn's disease [CD] through expressing proinflammatory adipokines from dysfunctional adipocytes by unknown mechanism. Adipocyte function is affected by dynamic adipose tissue extracellular matrix [ECM] remodelling that is mainly mediated by macrophages, and our study aimed to reveal whether aberrant ECM remodelling was present in CD-htMAT and its effects on adipocyte dysfunction, as well as the mechanism.

METHODS

ECM remodelling was examined in MAT samples from CD patients and controls. Mice with dinitrobenzene sulphonic acid [DNBS]-induced colitis were used in vivo study, and lipopolysaccharide [LPS]-induced remodelling behaviour in macrophages was examined in vitro. Macrophages or TLR4 inhibition were used to analyse ECM remodelling mechanisms and their effects on adipocyte function.

RESULTS

Aberrant ECM remodelling: was observed in CD-htMAT, which was characterised by a widened and deformed ECM structure accompanied by dysregulated matrix synthesis and degradation; served as a reservoir for inflammatory factors/cells dominated by macrophages; and was involved in adipocyte dysfunction. In addition, macrophages were the main source of ECM remodelling regulatory factors with activation of Toll-like receptor 4 [TLR4] in htMAT. In vivo, macrophage depletion or TLR4 inhibition largely attenuated mesenteric ECM remodelling while improving mesenteric adipocyte dysfunction during chronic enteritis. In vitro, antagonizing TLR4 significantly inhibited LPS-induced macrophage ECM remodelling behavior.

CONCLUSIONS

The aberrant ECM remodelling in CD-htMAT contributed to mesenteric adipocyte dysfunction, which may be caused at least partly by TLR4-mediated macrophage remodelling behavior. Inhibiting ECM remodelling may be a potential therapeutic strategy for CD.

Ginkgo biloba Extract Stimulates Adipogenesis in 3T3-L1 Preadipocytes

Smaller adipocytes are related to the reversal of metabolic disorders, suggesting that molecules that can act in the adipogenesis pathway are of great interest. The objective of this study was to investigate the effect of Ginkgo biloba extract (GbE) in modulating the differentiation in preadipocytes. 3T3-L1 preadipocytes were differentiated for 7 days into adipocytes without (control group) and with GbE at 1.0 mg/mL. Lipid content and gene expression were analyzed on day 7 (D7) by Oil Red O staining and PCR Array Gene Expression. Western blotting analysis of the key adipogenesis markers was evaluated during the differentiation process at days 3 (D3), 5 (D5), and 7 (D7). GbE increased lipid content and raised the gene expression of the main adipogenesis markers. Key proteins of the differentiation process were modulated by GbE, since C/EBPβ levels were decreased, while C/EBPα levels were increased at D7. Regarding the mature adipocytes’ markers, GbE enhanced the levels of both FABP4 at D5, and perilipin at D3 and D5. In summary, the present findings showed that GbE modulated the adipogenesis pathway suggesting that the treatment could accelerate the preadipocyte maturation, stimulating the expression of mature adipocyte proteins earlier than expected.

Analytical performance of a canine ELISA monocyte chemoattractant protein-1 assay for use in cats and evaluation of circulating levels in normal weight and obese cats

BACKGROUND

In human and murine obesity, adipose tissue dwelling macrophages and adipocytes produce monocyte chemoattractant protein-1 (MCP-1) leading to systemic low-grade inflammation. The aim of the study was to validate a canine MCP-1 ELISA assay for use in cats and to investigate whether a difference in MCP-1 concentrations could be detected between: a) cats having normal or elevated circulating serum amyloid A (SAA) levels and b) normal weight and obese cats. Serum obtained from 36 client-owned cats of various breed, age and sex with normal (n = 20) to elevated SAA (n = 16) was used for the validation of the canine MCP-1 ELISA assay. As no golden standard exists for measurement of inflammation, circulating MCP-1 concentrations were compared to SAA measurements, as an indicator of systemic inflammation. Analytical precision, dilution recovery and detection limit were calculated. A possible correlation between MCP-1 concentrations and obesity related measures (body fat percentage (BF%), insulin sensitivity and cytokine expression) were investigated in another population of 73 healthy, lean to obese, neutered domestic short-haired cats.

RESULTS

Intra- (2.7-4.1%) and inter-assay (2.2-3.6%) coefficient of variation and dilution recovery were acceptable, and the detection limit was 27.1 pg/mL. MCP-1 did not correlate with SAA, and there was no difference between the inflammatory (SAA > 20 mg/L) and non-inflammatory group, due to a marked overlap in MCP-1 concentrations. Circulating MCP-1 concentrations were unaffected by BF% (r2 = 2.7 × 10-6, P = 0.21) and other obesity-related markers.

CONCLUSIONS

The present canine ELISA assay seems to be able to measure circulating feline MCP-1. However, further studies are needed to determine its possible use for detecting inflammation in relation to disease processes or obesity-related low-grade inflammation in cats.

Role of adipose tissue macrophages in obesity-related disorders

The obesity epidemic has led researchers and clinicians to reconsider the etiology of this disease and precisely decipher its molecular mechanisms. The excessive accumulation of fat by cells, most notably adipocytes, which play a key role in this process, has many repercussions in tissue physiology. Herein, we focus on how macrophages, immune cells well known for their tissue gatekeeping functions, assume fundamental, yet ill-defined, roles in the genesis and development of obesity-related metabolic disorders. We first discuss the determinants of the biology of these cells before introducing the specifics of the adipose tissue environment, while highlighting its heterogeneity. Finally, we detail how obesity transforms both adipose tissue and local macrophage populations. Understanding macrophage diversity and their cross talk with the diverse cell types constituting the adipose tissue environment will allow us to frame the therapeutic potential of adipose tissue macrophages in obesity.

The impact of body composition on mortality of COVID-19 hospitalized patients: A prospective study on abdominal fat, obesity paradox and sarcopenia

Background & aims

Obesity has been described as a predisposing risk factor to severe forms of COVID-19, but conflicting results are emerging on its real impact on the mortality of COVID-19. We aimed to compare clinical outcomes and mortality among COVID-19 patients according to obesity, metabolic syndrome and adiposity distribution.

Methods

We conducted a prospective observational study of all consecutive adult patients with a confirmed diagnosis of SARS-CoV-2 infection admitted to the Infectious Diseases Clinic at Udine Hospital, Italy, from January 2021 to February 2021. At admission, the study population was submitted to specific anthropometric, laboratory and bioimpedance analysis (BIA) measurements and divided into five groups according to: 1) BMI < or >30 kg/m²; 2) waist circumference (WC) < or >98 cm for women, < or >102 cm for men; 3) presence or absence of metabolic syndrome (MS); 4) visceral adipose tissue (VAT) distribution; and 5) presence or absence of sarcopenia (SP) both based on BIA. We then compared clinical outcomes (ventilatory support, intensive care unit (ICU) admission, ICU length of stay, total hospital length of stay and mortality), immune and inflammatory makers and infectious and non-infectious acute complications within the five groups.

Results

A total of 195 patients were enrolled in the study. The mean age of patients was 71 years (IQR 61–80) and 64.6% (126) were male. The most common comorbidities were hypertension (55.9%) and MS (55.4%). Overall mortality was 19.5%. Abdominal adiposity, measured both with WC and with BIA, and SP were significantly associated with need for increased ventilator support (p = 0.013 for WC; p = 0.037, 0.027 and 0.009 for VAT; p = 0.004 and 0.036 for FMI; and p = 0.051 for SP), but not with ICU admission (WC p = 0.627, VAT p = 0.153, FMI p = 0.519 and SP p = 0.938), length of stay (WC p = 0.345, VAT p = 0.650, FMI p = 0.159 and SP p = 0.992) and mortality (WC p = 0.277, VAT p = 0.533, FMI p = 0.957 and SP p = 0.211). Obesity and MS did not discriminate for the intensity of ventilatory outcome (p = 0.142 and p = 0.198, respectively), ICU admission (p = 0.802 and p = 0.947, respectively), length of stay (p = 0.471 and p = 0.768, respectively) and mortality (p = 0.495 and p = 0.268, respectively). We did not find significant differences in inflammatory markers and secondary complications within the five groups.

Conclusions

In patients admitted with COVID-19, increased WC, visceral abdominal fat and SP are associated with higher need for ventilatory support. However, obesity, MS, SP and abdominal adiposity are not sensitive predictive factors for mortality.

The importance of AMPK in obesity and chronic diseases and the relationship of AMPK with nutrition: a literature review

This review will examine the role of 5'-adenosine monophosphate-activated protein kinase (AMPK) in the treatment of obesity, medical nutrition and chronic diseases, and its relationship with nutrition. In the literature, the number of studies examining the direct relationship of AMPK with nutrition is negligible. For this reason, information on the subject has been compiled from all the studies that can be accessed by searching the terms AMPK and disease, AMPK and health, AMPK and exercise, AMPK and nutrition. It can be stated that AMPK is inhibited in many pathological conditions such as inflammation, diabetes, aging and cancer, and AMPK activation has positive effects in many diseases such as insulin resistance, diabetes, obesity, cancer and Alzheimer's. When the relationship between nutrition and AMPK is examined, it is seen that food intake inhibits AMPK, but especially high-carbohydrate and fatty diets are more effective at this point. In addition, high fructose corn sirup and long chain saturated fatty acids increased by consumption of industrial foods and frequent meals appear to be an inactivator for AMPK. For AMPK activation in medical nutrition therapy, it is recommended to use methods such as evening fasting and intermittent fasting, taking into account the human circadian rhythm.

Use of Physical Activity and Exercise to Reduce Inflammation in Children and Adolescents with Obesity

Childhood obesity is a leading public health problem worldwide, as it is increasingly prevalent and therefore responsible for serious obesity-related comorbidities, not only in childhood but also in adulthood. In addition to cardio-metabolic obesity-related disorders, recent evidence suggests that excess adipose tissue in turn is associated with immune cell infiltration, increased adipokine release, and the development of low-grade systemic inflammation obesity. Exercise is considered a non-pharmacological intervention that can delay obesity-related comorbidities, improving cardiovascular fitness and modulating the inflammatory processes. It has been reported that the anti-inflammatory effect of regular exercise may be mediated by a reduction in visceral fat mass, with a subsequent decrease in the release of adipokines from adipose tissue (AT) and/or by the induction of an anti-inflammatory environment. In this narrative review, we discuss the role of AT as an endocrine organ associated with chronic inflammation and its role in obesity-related complications, focusing on the effect of exercise in reducing inflammation in children and adolescents with obesity. Regular physical exercise must be considered as a natural part of a healthy lifestyle, and promoting physical activity starting from childhood is useful to limit the negative effects of obesity on health. The crucial role of the immune system in the development of obesity-induced inflammatory processes and the efficacy of exercise as an anti-inflammatory, non-pharmacological intervention may provide possible targets for the development of new treatments and early preventive strategies.

Periprostatic Adipose Tissue Displays a Chronic Hypoxic State that Limits Its Expandability

White adipose tissue accumulates at various sites throughout the body, some adipose tissue depots exist near organs whose function they influence in a paracrine manner. Prostate gland is surrounded by a poorly characterized adipose depot called periprostatic adipose tissue (PPAT), which plays emerging roles in prostate-related disorders. Unlike all other adipose depots, PPAT secretes proinflammatory cytokines even in lean individuals and does not increase in volume during obesity. These unique features remain unexplained because of the poor structural and functional characterization of this tissue. This study characterized the structural organization of PPAT in patients compared with abdominopelvic adipose tissue (APAT), an extraperitoneal adipose depot, the accumulation of which is correlated to body mass index. Confocal microscopy followed by three-dimensional reconstructions showed a sparse vascular network in PPAT when compared with that in APAT, suggesting that this tissue is hypoxic. Unbiased comparisons of PPAT and APAT transcriptomes found that most differentially expressed genes were related to the hypoxia response. High levels of the hypoxia-inducible factor 2α confirmed the presence of an adaptive response to hypoxia in PPAT. This chronic hypoxic state was associated with inflammation and fibrosis, which were not further up-regulated by obesity. This fibrosis and inflammation explain the failure of PPAT to expand in obesity and open new mechanistic avenues to explain its role in prostate-related disorders, including cancer.

Immunonutrition and SARS-CoV-2 Infection in Children with Obesity

Since the beginning of the SARS-CoV-2 pandemic, there has been much discussion about the role of diet and antiviral immunity in the context of SARS-CoV-2 infection. Intake levels of vitamins D, C, B12, and iron have been demonstrated to be correlated with lower COVID-19 incidence and mortality. Obesity has been demonstrated to be an independent risk for the severity of COVID-19 infection in adults and also in children. This may be due to different mechanisms, mainly including the gut dysbiosis status observed in obese children. Moreover, the existence of a gut-lung axis added new knowledge to on the potential mechanisms by which diet and dietary substances may affect immune function. The aim of this narrative review is to address the intricate inter-relationship between COVID-19, immune function, and obesity-related inflammation and to describe the role of nutrients and dietary patterns in enhancing the immune system. Two ways to fight against COVID-19 disease exist: one with an antiviral response through immune system boosting and another with antioxidants with an anti-inflammatory effect. In the current pandemic situation, the intake of a varied and balanced diet, rich in micronutrients and bioactive compounds including fibers, should be recommended. However, clinical studies conducted on children affected by SARS-CoV-2 infection and comorbidity are warranted.

Leptin as a key regulator of the adipose organ

Leptin is a hormone primarily produced by the adipose tissue in proportion to the size of fat stores, with a primary function in the control of lipid reserves. Besides adipose tissue, leptin is also produced by other tissues, such as the stomach, placenta, and mammary gland. Altogether, leptin exerts a broad spectrum of short, medium, and long-term regulatory actions at the central and peripheral levels, including metabolic programming effects that condition the proper development and function of the adipose organ, which are relevant for its main role in energy homeostasis. Comprehending how leptin regulates adipose tissue may provide important clues to understand the pathophysiology of obesity and related diseases, such as type 2 diabetes, as well as its prevention and treatment. This review focuses on the physiological and long-lasting regulatory effects of leptin on adipose tissue, the mechanisms and pathways involved, its main outcomes on whole-body physiological homeostasis, and its consequences on chronic diseases.

The Influence of Obesity and Weight Loss on the Bioregulation of Innate/Inflammatory Responses: Macrophages and Immunometabolism

Obesity is characterized by low-grade inflammation and more susceptibility to infection, particularly viral infections, as clearly demonstrated in COVID-19. In this context, immunometabolism and metabolic flexibility of macrophages play an important role. Since inflammation is an inherent part of the innate response, strategies for decreasing the inflammatory response must avoid immunocompromise the innate defenses against pathogen challenges. The concept “bioregulation of inflammatory/innate responses” was coined in the context of the effects of exercise on these responses, implying a reduction in excessive inflammatory response, together with the preservation or stimulation of the innate response, with good transitions between pro- and anti-inflammatory macrophages adapted to each individual’s inflammatory set-point in inflammatory diseases, particularly in obesity. The question now is whether these responses can be obtained in the context of weight loss by dietary interventions (low-fat diet or abandonment of the high-fat diet) in the absence of exercise, which can be especially relevant for obese individuals with difficulties exercising such as those suffering from persistent COVID-19. Results from recent studies are controversial and do not point to a clear anti-inflammatory effect of these dietary interventions, particularly in the adipose tissue. Further research focusing on the innate response is also necessary.

Leptin in the Respiratory Tract: Is There a Role in SARS-CoV-2 Infection?

Leptin is a pleiotropic adipocytokine involved in several physiologic functions, with a known role in innate and adaptive immunity as well as in tissue homeostasis. Long- and short-isoforms of leptin receptors are widely expressed in many peripheral tissues and organs, such as the respiratory tract. Similar to leptin, microbiota affects the immune system and may interfere with lung health through the bidirectional crosstalk called the “gut-lung axis.” Obesity leads to impaired protective immunity and altered susceptibility to pulmonary infections, as those by severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2). Although it is known that leptin and microbiota link metabolism and lung health, their role within the SARS-CoV2 coronavirus disease 2019 (COVID-19) deserves further investigations. This review aimed to summarize the available evidence about: (i) the role of leptin in immune modulation; (ii) the role of gut microbiota within the gut-lung axis in modulating leptin sensitivity; and (iii) the role of leptin in the pathophysiology of COVID-19.

OUP accepted manuscript

Cells of the stromal vascular fraction (SVF) of human adipose tissue have the capacity to generate osteogenic grafts with intrinsic vasculogenic properties. However, cultured adipose-derived stromal cells (ASCs), even after minimal monolayer expansion, lose osteogenic capacity in vivo. Communication between endothelial and stromal/mesenchymal cell lineages has been suggested to improve bone formation and vascularization by engineered tissues. Here, we investigated the specific role of a subpopulation of SVF cells positive for T-cadherin (T-cad), a putative endothelial marker. We found that maintenance during monolayer expansion of a T-cad-positive cell population, composed of endothelial lineage cells (ECs), is mandatory to preserve the osteogenic capacity of SVF cells in vivo and strongly supports their vasculogenic properties. Depletion of T-cad-positive cells from the SVF totally impaired bone formation in vivo and strongly reduced vascularization by SVF cells in association with decreased VEGF and Adiponectin expression. The osteogenic potential of T-cad-depleted SVF cells was fully rescued by co-culture with ECs from a human umbilical vein (HUVECs), constitutively expressing T-cad. Ectopic expression of T-cad in ASCs stimulated mineralization in vitro but failed to rescue osteogenic potential in vivo, indicating that the endothelial nature of the T-cad-positive cells is the key factor for induction of osteogenesis in engineered grafts based on SVF cells. This study demonstrates that crosstalk between stromal and T-cad expressing endothelial cells within adipose tissue critically regulates osteogenesis, with VEGF and adiponectin as associated molecular mediators.

Network Analyses Reveal Negative Link Between Changes in Adipose Tissue GDF15 and BMI During Dietary-induced Weight Loss

CONTEXT

Adipose tissue (AT) transcriptome studies provide holistic pictures of adaptation to weight and related bioclinical settings changes.

OBJECTIVE

To implement AT gene expression profiling and investigate the link between changes in bioclinical parameters and AT gene expression during 3 steps of a 2-phase dietary intervention (DI).

METHODS

AT transcriptome profiling was obtained from sequencing 1051 samples, corresponding to 556 distinct individuals enrolled in a weight loss intervention (8-week low-calorie diet (LCD) at 800 kcal/day) followed with a 6-month ad libitum randomized DI. Transcriptome profiles obtained with QuantSeq sequencing were benchmarked against Illumina RNAseq. Reverse transcription quantitative polymerase chain reaction was used to further confirm associations. Cell specificity was assessed using freshly isolated cells and THP-1 cell line.

RESULTS

During LCD, 5 modules were found, of which 3 included at least 1 bioclinical variable. Change in body mass index (BMI) connected with changes in mRNA level of genes with inflammatory response signature. In this module, change in BMI was negatively associated with changes in expression of genes encoding secreted protein (GDF15, CCL3, and SPP1). Through all phases of the DI, change in GDF15 was connected to changes in SPP1, CCL3, LIPA and CD68. Further characterization showed that these genes were specific to macrophages (with LIPA, CD68 and GDF15 expressed in anti-inflammatory macrophages) and GDF15 also expressed in preadipocytes.

CONCLUSION

Network analyses identified a novel AT feature with GDF15 upregulated with calorie restriction induced weight loss, concomitantly to macrophage markers. In AT, GDF15 was expressed in preadipocytes and macrophages where it was a hallmark of anti-inflammatory cells.

Adipoclast: a multinucleated fat-eating macrophage

Cell membrane fusion and multinucleation in macrophages are associated with physiologic homeostasis as well as disease. Osteoclasts are multinucleated macrophages that resorb bone through increased metabolic activity resulting from cell fusion. Fusion of macrophages also generates multinucleated giant cells (MGCs) in white adipose tissue (WAT) of obese individuals. For years, our knowledge of MGCs in WAT has been limited to their description as part of crown-like structures (CLS) surrounding damaged adipocytes. However, recent evidence indicates that these cells can phagocytose oversized lipid remnants, suggesting that, as in osteoclasts, cell fusion and multinucleation are required for specialized catabolic functions. We thus reason that WAT MGCs can be viewed as functionally analogous to osteoclasts and refer to them in this article as adipoclasts. We first review current knowledge on adipoclasts and their described functions. In view of recent advances in single cell genomics, we describe WAT macrophages from a ‘fusion perspective’ and speculate on the ontogeny of adipoclasts. Specifically, we highlight the role of CD9 and TREM2, two plasma membrane markers of lipid-associated macrophages in WAT, which have been previously described as regulators of fusion and multinucleation in osteoclasts and MGCs. Finally, we consider whether strategies aiming to target WAT macrophages can be more selectively directed against adipoclasts.

Insulin Resistance and Cancer: In Search for a Causal Link

Insulin resistance (IR) is a condition which refers to individuals whose cells and tissues become insensitive to the peptide hormone, insulin. Over the recent years, a wealth of data has made it clear that a synergistic relationship exists between IR, type 2 diabetes mellitus, and cancer. Although the underlying mechanism(s) for this association remain unclear, it is well established that hyperinsulinemia, a hallmark of IR, may play a role in tumorigenesis. On the other hand, IR is strongly associated with visceral adiposity dysfunction and systemic inflammation, two conditions which favor the establishment of a pro-tumorigenic environment. Similarly, epigenetic modifications, such as DNA methylation, histone modifications, and non-coding RNA, in IR states, have been often associated with tumorigenesis in numerous types of human cancer. In addition to these observations, it is also broadly accepted that gut microbiota may play an intriguing role in the development of IR-related diseases, including type 2 diabetes and cancer, whereas potential chemopreventive properties have been attributed to some of the most commonly used antidiabetic medications. Herein we provide a concise overview of the most recent literature in this field and discuss how different but interrelated molecular pathways may impact on tumor development.

Protective and ameliorating effects of probiotics against diet-induced obesity: A review

Diet-induced obesity is one of the major public health concerns all over the world, and obesity also contributes to the development of other chronic diseases such as non-alcoholic fatty acid liver disease, type 2 diabetes mellitus and cardiovascular diseases. Evidence shows that the pathogenesis of obesity and obesity-associated chronic diseases are closely related to dysregulation of lipid metabolism, glucose metabolism and cholesterol metabolism, and oxidative stress, endoplasmic reticulum stress, abnormal gut microbiome and chronic low-grade inflammation. Recently, in view of potential effects on lipid metabolism, glucose metabolism, cholesterol metabolism and intestinal microbiome, as well as anti-oxidative and anti-inflammatory activities, natural probiotics, including live and dead probiotics, and probiotic components and metabolites, have attracted increasing attention and are considered as novel strategies for preventing and ameliorating obesity and obesity-related chronic diseases. Specifically, this review is presented on the anti-obesity effects of probiotics and underlying molecular mechanisms, which will provide a theoretical basis of anti-obesity probiotics for the development of functional foods.

Circadian clock dysfunction in human omental fat links obesity to metabolic inflammation

To unravel the pathogenesis of obesity and its complications, we investigate the interplay between circadian clocks and NF-κB pathway in human adipose tissue. The circadian clock function is impaired in omental fat from obese patients. ChIP-seq analyses reveal that the core clock activator, BMAL1 binds to several thousand target genes. NF-κB competes with BMAL1 for transcriptional control of some targets and overall, BMAL1 chromatin binding occurs in close proximity to NF-κB consensus motifs. Obesity relocalizes BMAL1 occupancy genome-wide in human omental fat, thereby altering the transcription of numerous target genes involved in metabolic inflammation and adipose tissue remodeling. Eventually, clock dysfunction appears at early stages of obesity in mice and is corrected, together with impaired metabolism, by NF-κB inhibition. Collectively, our results reveal a relationship between NF-κB and the molecular clock in adipose tissue, which may contribute to obesity-related complications.

Effect of Panax notoginseng Saponins and Major Anti-Obesity Components on Weight Loss

The prevalence of individuals who are overweight or obese is rising rapidly globally. Currently, majority of drugs used to treat obesity are ineffective or are accompanied by obvious side effects; hence, the options are very limited. Therefore, it is necessary to find more effective and safer anti-obesity drugs. It has been proven in vivo and in vitro that the active ingredient notoginsenosides isolated from traditional Chinese medicine Panax notoginseng (Burk.) F. H. Chen exhibits anti-obesity effects. Notoginsenosides can treat obesity by reducing lipid synthesis, inhibiting adipogenesis, promoting white adipose tissue browning, increasing energy consumption, and improving insulin sensitivity. Although notoginsenosides are potential drugs for the treatment of obesity, their effects and mechanisms have not been analyzed in depth. In this review, the anti-obesity potential and mechanism of action of notoginsenosides were analyzed; thus laying emphasis on the timely prevention and treatment of obesity.

Susceptibility and Severity of Viral Infections in Obesity: Lessons from Influenza to COVID-19. Does Leptin Play a Role?

The recent pandemic Sars-CoV2 infection and studies on previous influenza epidemic have drawn attention to the association between the obesity and infectious diseases susceptibility and worse outcome. Metabolic complications, nutritional aspects, physical inactivity, and a chronic unbalance in the hormonal and adipocytokine microenvironment are major determinants in the severity of viral infections in obesity. By these pleiotropic mechanisms obesity impairs immune surveillance and the higher leptin concentrations produced by adipose tissue and that characterize obesity substantially contribute to such immune response dysregulation. Indeed, leptin not only controls energy balance and body weight, but also plays a regulatory role in the interplay between energy metabolism and immune system. Since leptin receptor is expressed throughout the immune system, leptin may exert effects on cells of both innate and adaptive immune system. Chronic inflammatory states due to metabolic (i.e., obesity) as well as infectious diseases increase leptin concentrations and consequently lead to leptin resistance further fueling inflammation. Multiple factors, including inflammation and ER stress, contribute to leptin resistance. Thus, if leptin is recognized as one of the adipokines responsible for the low grade inflammation found in obesity, on the other hand, impairments of leptin signaling due to leptin resistance appear to blunt the immunologic effects of leptin and possibly contribute to impaired vaccine-induced immune responses. However, many aspects concerning leptin interactions with inflammation and immune system as well as the therapeutical approaches to overcome leptin resistance and reduced vaccine effectiveness in obesity remain a challenge for future research.

The Weight of Obesity in Immunity from Influenza to COVID-19

The severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) has emerged in December 2019 and rapidly outspread worldwide endangering human health. The coronavirus disease 2019 (COVID-19) manifests itself through a wide spectrum of symptoms that can evolve to severe presentations as pneumonia and several non-respiratory complications. Increased susceptibility to COVID-19 hospitalization and mortality have been linked to associated comorbidities as diabetes, hypertension, cardiovascular diseases and, recently, to obesity. Similarly, individuals living with obesity are at greater risk to develop clinical complications and to have poor prognosis in severe influenza pneumonia. Immune and metabolic dysfunctions associated with the increased susceptibility to influenza infection are linked to obesity-associated low-grade inflammation, compromised immune and endocrine systems, and to high cardiovascular risk. These preexisting conditions may favor virological persistence, amplify immunopathological responses and worsen hemodynamic instability in severe COVID-19 as well. In this review we highlight the main factors and the current state of the art on obesity as risk factor for influenza and COVID-19 hospitalization, severe respiratory manifestations, extrapulmonary complications and even death. Finally, immunoregulatory mechanisms of severe influenza pneumonia in individuals with obesity are addressed as likely factors involved in COVID-19 pathophysiology.

Gab2 deficiency suppresses high-fat diet-induced obesity by reducing adipose tissue inflammation and increasing brown adipose function in mice

Obesity is caused by a long-term imbalance between energy intake and consumption and is regulated by multiple signals. This study investigated the effect of signaling scaffolding protein Gab2 on obesity and its relevant regulation mechanism. Gab2 knockout (KO) and wild-type (WT) mice were fed with a standard diet (SD) or high-fat diet (HFD) for 12 weeks. The results showed that the a high-fat diet-induced Gab2 expression in adipose tissues, but deletion of Gab2 attenuated weight gain and improved glucose tolerance in mice fed with a high-fat diet. White adipose tissue and systemic inflammations were reduced in HFD-fed Gab2 deficiency mice. Gab2 deficiency increased the expression of Ucp1 and other thermogenic genes in brown adipose tissue. Furthermore, the regulation of Gab2 on the mature differentiation and function of adipocytes was investigated in vitro using primary or immortalized brown preadipocytes. The expression of brown fat-selective genes was found to be elevated in differentiated adipocytes without Gab2. The mechanism of Gab2 regulating Ucp1 expression in brown adipocytes involved with its downstream PI3K (p85)-Akt-FoxO1 signaling pathway. Our research suggests that deletion of Gab2 suppresses diet-induced obesity by multiple pathways and Gab2 may be a novel therapeutic target for the treatment of obesity and associated complications.

Autophagy and proinflammatory cytokine expression in the intestinal mucosa and mesenteric fat tissue of patients with Crohn's disease

Background Recently, mesenteric fat has been proposed to play a role in the pathophysiol- ogy of Crohn's disease (CD), as fat hypertrophy is detected close to the affected intestinal area; however, there are few studies regarding autophagy and creeping fat tissue in CD.

Objective Evaluate autophagy-related proteins and proinflammatory cytokines in intestinal mucosa and mesenteric fat in patients with CD and controls.

Patients and methods Ten patients with CD, eight with non-inflammatory disease who underwent surgery, and eight with normal ileocolonoscopy were studied. The expression of LC3-II, TNF-α and IL-23 was determined by immunoblot of protein extracts. In addition, total RNA of LC3 and Atg16-L1 were determined using RT-PCR.

Results The expression of LC3-II was significantly lower in the mesenteric tissue of CD when compared to controls (p < 0.05). In contrast, the intestinal mucosa of the CD group had higher levels of LC3-II (p < 0.05). However, mRNA expression of autophagy-related pro- teins was similar when compared to mesenteric fat groups. TNF-α and IL-23 expressions were higher in intestinal mucosa of CD than in control (p < 0.05).

Conclusion These findings suggest a defect in the autophagic activity of the creeping fat tissue in CD, which could be involved with the maintenance of the inflammatory process in the intestinal mucosa.

Mitochondrial Functionality in Inflammatory Pathology-Modulatory Role of Physical Activity

The incidence and severity of metabolic diseases can be reduced by introducing healthy lifestyle habits including moderate exercise. A common observation in age-related metabolic diseases is an increment in systemic inflammation (the so-called inflammaging) where mitochondrial reactive oxygen species (ROS) production may have a key role. Exercise prevents these metabolic pathologies, at least in part, due to its ability to alter immunometabolism, e.g., reducing systemic inflammation and by improving immune cell metabolism. Here, we review how exercise regulates immunometabolism within contracting muscles. In fact, we discuss how circulating and resident macrophages alter their function due to mitochondrial signaling, and we propose how these effects can be triggered within skeletal muscle in response to exercise. Finally, we also describe how exercise-induced mitochondrial adaptations can help to fight against virus infection. Moreover, the fact that moderate exercise increases circulating immune cells must be taken into account by public health agencies, as it may help prevent virus spread. This is of interest in order to face not only acute respiratory-related coronavirus (SARS-CoV) responsible for the COVID-19 pandemic but also for future virus infection challenges.

Adipose tissue inflammation and metabolic dysfunction in obesity

Several lines of preclinical and clinical research have confirmed that chronic low-grade inflammation of adipose tissue is mechanistically linked to metabolic disease and organ tissue complications in the overweight and obese organism. Despite this widely confirmed paradigm, numerous open questions and knowledge gaps remain to be investigated. This is mainly due to the intricately intertwined cross-talk of various pro- and anti-inflammatory signaling cascades involved in the immune response of expanding adipose depots, particularly the visceral adipose tissue. Adipose tissue inflammation is initiated and sustained over time by dysfunctional adipocytes that secrete inflammatory adipokines and by infiltration of bone marrow-derived immune cells that signal via production of cytokines and chemokines. Despite its low-grade nature, adipose tissue inflammation negatively impacts remote organ function, a phenomenon that is considered causative of the complications of obesity. The aim of this review is to broadly present an overview of adipose tissue inflammation by highlighting the most recent reports in the scientific literature and summarizing our overall understanding of the field. We also discuss key endogenous anti-inflammatory mediators and analyze their mechanistic role(s) in the pathogenesis and treatment of adipose tissue inflammation. In doing so, we hope to stimulate studies to uncover novel physiological, cellular, and molecular targets for the treatment of obesity.

The hematologic consequences of obesity

The prevalence of obesity is increasing and progressively influencing physician-patient interactions. While there is a sizable amount of data demonstrating that obesity is a state of low-grade inflammation, to our knowledge, there is no single review summarizing its effects on hematologic parameters and thrombotic risk. We performed a literature search which largely surfaced observational studies, with a few systematic reviews and meta-analyses of these studies. We took care to review the mechanisms driving an inflammatory state and obesity's effect on white blood cells, red blood cells, platelets, and thrombotic risk. There is an observed relative, and sometimes absolute leukocytosis driven by this inflammatory state. Obesity is also associated with increased platelet counts and an increased risk for venous thromboembolism (VTE). Lastly, the association between obesity, iron deficiency (ID), and red blood cell counts may be present but remains uncertain. Recognizing the above associations may provide clinicians with reassurance regarding otherwise unexplained hematologic abnormalities in obese individuals. We hope this review will prompt future studies to further understand the underlying mechanisms driving these abnormalities and identify modifiable risk factors and potential therapeutic targets to prevent the development of probable obesity-associated conditions with significant morbidity and mortality, such as ID and VTE.

Sex Affects Regional Variations in Subcutaneous Adipose Tissue T Cells but not Macrophages in Adults with Obesity

OBJECTIVE

The inflammatory environment in lower-body subcutaneous adipose tissue (SAT) has been largely unexplored. This study aimed to examine the effects of region (upper body vs. lower body) and sex on SAT immune cell profiles in young adults with obesity.

METHODS

Abdominal (AB) and femoral (FEM) SAT was collected from 12 males (mean [SEM] age = 30.8 [1.4] years; mean [SEM] BMI = 34.1 [1.1] kg/m² ) and 22 females (mean [SEM] age = 30.6 [0.6] years; mean [SEM] BMI = 34.0 [0.7] kg/m² ) with obesity via needle aspiration. Flow cytometry was used to quantify macrophage (CD68+) and T-cell (CD3+) subpopulations in the stromovascular fraction of each SAT region.

RESULTS

Females had a greater proportion of most T-cell types (CD3+CD4+CD45RA+, CD3+CD4+CD45RA-, and CD3+CD8+CD45RA+) in FEM compared with AB SAT, while males had similar proportions in both regions. Regardless of sex, the M1-like macrophage population (CD68+CD206-) was proportionally higher in AB SAT than in FEM SAT.

CONCLUSIONS

Results showed that T-cell populations vary by SAT region in females but not males. Both sexes, however, have proportionately more proinflammatory macrophages in upper-body than in lower-body SAT. It remains to be seen how these unique immune cell profiles in males and females with obesity contribute to adipose tissue inflammation and metabolic disease risk.

Visfatin and Rheumatoid Arthritis: Pathogenetic Implications and Clinical Utility

Objective:

Analysis and generalization of data related to visfatin involvement in the pathogenesis of inflammation at various stages of rheumatoid arthritis.

Data Synthesis:

Visfatin is an adipocytokine which has also been identified in non-adipose tissues. It influences directly on the maturation of B cells, which are involved in autoantibody production and T cell activation. Visfatin can promote inflammation via regulation of pro-inflammatory cytokines including TNF, IL-1β and IL-6. The concentration of circulating visfatin in rheumatoid arthritis patients is higher compared to healthy individuals. Several studies suggest that visfatin level is associated with rheumatoid arthritis activity, and its elevation may precede clinical signs of the relapse. In murine collagen-induced arthritis, visfatin levels were also found to be elevated both in inflamed synovial cells and in joint vasculature. Visfatin blockers have been shown to confer fast and long-term attenuation of pathological processes; however, most of their effects are transient. Other factors responsible for hyperactivation of the immune system can participate in this process at a later stage. Treatment of rheumatoid arthritis with a combination of these blockers and inhibitors of other mediators of inflammation can potentially improve treatment outcomes compared to current therapeutic strategies. Recent advances in the treatment of experimental arthritis in mice as well as the application of emerging treatment strategies obtained from oncology for rheumatoid arthritis management could be a source of novel adipokine-mediated anti-rheumatic drugs.

Conclusion:

The ongoing surge of interest in anticytokine therapy makes further study of visfatin highly relevant as it may serve as a base for innovational RA treatment.

Biomimetic 3D Models for Investigating the Role of Monocytes and Macrophages in Atherosclerosis

Atherosclerosis, the inflammation of artery walls due to the accumulation of lipids, is the most common underlying cause for cardiovascular diseases. Monocytes and macrophages are major cells that contribute to the initiation and progression of atherosclerotic plaques. During this process, an accumulation of LDL-laden macrophages (foam cells) and an alteration in the extracellular matrix (ECM) organization leads to a local vessel stiffening. Current in vitro models are carried out onto two-dimensional tissue culture plastic and cannot replicate the relevant microenvironments. To bridge the gap between in vitro and in vivo conditions, we utilized three-dimensional (3D) collagen matrices that allowed us to mimic the ECM stiffening during atherosclerosis by increasing collagen density. First, human monocytic THP-1 cells were embedded into 3D collagen matrices reconstituted at low and high density. Cells were subsequently differentiated into uncommitted macrophages (M0) and further activated into pro- (M1) and anti-inflammatory (M2) phenotypes. In order to mimic atherosclerotic conditions, cells were cultured in the presence of oxidized LDL (oxLDL) and analyzed in terms of oxLDL uptake capability and relevant receptors along with their cytokine secretomes. Although oxLDL uptake and larger lipid size could be observed in macrophages in a matrix dependent manner, monocytes showed higher numbers of oxLDL uptake cells. By analyzing major oxLDL uptake receptors, both monocytes and macrophages expressed lectin-like oxidized low-density lipoprotein receptor-1 (LOX1), while enhanced expression of scavenger receptor CD36 could be observed only in M2. Notably, by analyzing the secretome of macrophages exposed to oxLDL, we demonstrated that the cells could, in fact, secrete adipokines and growth factors in distinct patterns. Besides, oxLDL appeared to up-regulate MHCII expression in all cells, while an up-regulation of CD68, a pan-macrophage marker, was found only in monocytes, suggesting a possible differentiation of monocytes into a pro-inflammatory macrophage. Overall, our work demonstrated that collagen density in the plaque could be one of the major factors driving atherosclerotic progression via modulation of monocyte and macrophages behaviors.

Fgr kinase is required for proinflammatory macrophage activation during diet-induced obesity

Proinflammatory macrophages are key in the development of obesity. In addition, reactive oxygen species (ROS), which activate the Fgr tyrosine kinase, also contribute to obesity. Here we show that ablation of Fgr impairs proinflammatory macrophage polarization while preventing high-fat diet (HFD)-induced obesity in mice. Systemic ablation of Fgr increases lipolysis and liver fatty acid oxidation, thereby avoiding steatosis. Knockout of Fgr in bone marrow (BM)-derived cells is sufficient to protect against insulin resistance and liver steatosis following HFD feeding, while the transfer of Fgr-expressing BM-derived cells reverts protection from HFD feeding in Fgr-deficient hosts. Scavenging of mitochondrial peroxides is sufficient to prevent Fgr activation in BM-derived cells and HFD-induced obesity. Moreover, Fgr expression is higher in proinflammatory macrophages and correlates with obesity traits in both mice and humans. Thus, our findings reveal the mitochondrial ROS-Fgr kinase as a key regulatory axis in proinflammatory adipose tissue macrophage activation, diet-induced obesity, insulin resistance and liver steatosis.

There and Back Again: Leptin Actions in White Adipose Tissue

Leptin is a hormone discovered almost 30 years ago with important implications in metabolism. It is primarily produced by white adipose tissue (WAT) in proportion to the amount of fat. The discovery of leptin was a turning point for two principle reasons: on one hand, it generated promising expectations for the treatment of the obesity, and on the other, it changed the classical concept that white adipose tissue was simply an inert storage organ. Thus, adipocytes in WAT produce the majority of leptin and, although its primary role is the regulation of fat stores by controlling lipolysis and lipogenesis, this hormone also has implications in other physiological processes within WAT, such as apoptosis, browning and inflammation. Although a massive number of questions related to leptin actions have been answered, the necessity for further clarification facilitates constantly renewing interest in this hormone and its pathways. In this review, leptin actions in white adipose tissue will be summarized in the context of obesity.

CCL2/CCR2 signaling in cancer pathogenesis

Chemokines are a family of small cytokines, which guide a variety of immune/inflammatory cells to the site of tumor in tumorigenesis. A dysregulated expression of chemokines is implicated in different types of cancer including prostate cancer. The progression and metastasis of prostate cancer involve a complex network of chemokines that regulate the recruitment and trafficking of immune cells. The chemokine CCL2 and its main receptor CCR2 have been receiving particular interest on their roles in cancer pathogenesis. The up-regulation of CCL2/CCR2 and varied immune conditions in prostate cancer, are associated with cancer advancement, metastasis, and relapse. Here we reviewed recent findings, which link CCL2/CCR2 to the inflammation and cancer pathogenesis, and discussed the therapeutic potential of CCL2/CCR2 axis in cancer treatment based on results from our group and other investigators, with a major focus on prostate cancer. Video Abstract.

Propionic acid counteracts the inflammation of human subcutaneous adipose tissue: a new avenue for drug development

Adipose tissue is a primary site of obesity-induced inflammation, which has been emerging as an important contributor to obesity associated disorders. The factors influencing adipose tissue-induced inflammation and the resulting pathophysiological events remain poorly understood. However, dietary fiber consumptions appear to be protective. Short-chain fatty acids such as propionic acid (PA) are the principal products of the dietary fiber fermentation by microbiota. Therefore, we aim to investigate the influence of PA on inflammation, lipogenesis and glucose uptake markers from human subcutaneous adipose tissue (SAT). We showed that the treatment of SAT with PA resulted in a significant downregulation of inflammatory parameters (e.g. TNF-α and IP-10) and macrophage markers (e.g. CD163 and MMP-9). The expression levels of PA receptors (i.e. G protein coupled receptor-41 and -43) in human primary adipocytes were very low in comparison with SAT and macrophages. Upon PA treatment, no anti-inflammatory effect was observed in human adipocytes. PA significantly upregulated the expression of lipoprotein lipase (LPL), sterol regulatory-element-binding protein-1c (SREBP-1c) and glucose transporter 4 (GLUT-4), which are associated with lipogenesis and glucose uptake. We also showed that the observed anti-inflammatory effects of PA on SAT were partly mediated by Gi/o protein coupled receptor. Our data suggests that PA anti-inflammatory effects on SAT are mediated partly via Gi/o proteins, leading to the improved expression of factors associated with lipogenesis and glucose uptake. These responses appeared to be not mediated by adipocytes; but most probably by macrophages. The current study provides new knowledge, which can be used as a potential new avenue for drug development in preventing obesity-related inflammation and metabolic disorders in future.

Graphical abstract

White adipose tissue mitochondrial metabolism in health and in obesity

White adipose tissue is one of the largest organs of the body. It plays a key role in whole-body energy status and metabolism; it not only stores excess energy but also secretes various hormones and metabolites to regulate body energy balance. Healthy adipose tissue capable of expanding is needed for metabolic well-being and to prevent accumulation of triglycerides to other organs. Mitochondria govern several important functions in the adipose tissue. We review the derangements of mitochondrial function in white adipose tissue in the obese state. Downregulation of mitochondrial function or biogenesis in the white adipose tissue is a central driver for obesity-associated metabolic diseases. Mitochondrial functions compromised in obesity include oxidative functions and renewal and enlargement of the adipose tissue through recruitment and differentiation of adipocyte progenitor cells. These changes adversely affect whole-body metabolic health. Dysfunction of the white adipose tissue mitochondria in obesity has long-term consequences for the metabolism of adipose tissue and the whole body. Understanding the pathways behind mitochondrial dysfunction may help reveal targets for pharmacological or nutritional interventions that enhance mitochondrial biogenesis or function in adipose tissue.

Leptin in Tumor Microenvironment

Leptin is a hormone that plays a major role as mediator of long-term regulation of energy balance, suppressing food intake, and stimulating weight loss. More recently, important physiological roles other than controlling appetite and energy expenditure have been suggested for leptin, including neuroendocrine, reparative, reproductive, and immune functions. These emerging peripheral roles let hypothesize that leptin can modulate also cancer progression. Indeed, many studies have demonstrated that elevated chronic serum concentrations of leptin, frequently seen in obese subjects, represent a stimulatory signal for tumor growth. Current knowledge indicates that also different non-tumoral cells resident in tumor microenvironment may respond to leptin creating a favorable soil for cancer cells. In addition, leptin is produced also within the tumor microenvironment creating the possibility for paracrine and autocrine action. In this review, we describe the main mechanisms that regulate peripheral leptin availability and how leptin can shape tumor microenvironment.