scholarly journals Follistatin-Like 1: A Potential Mediator of Inflammation in Obesity

2013 ◽  
Vol 2013 ◽  
pp. 1-12 ◽  
Author(s):  
Nengguang Fan ◽  
Haiyan Sun ◽  
Yufan Wang ◽  
Yifei Wang ◽  
Lijuan Zhang ◽  
...  
Keyword(s):  
Insulin Resistance ◽  
Adipose Tissue ◽  
Molecular Mechanisms ◽  
Inflammatory Responses ◽  
Low Grade ◽  
Dependent Manner ◽  
Proinflammatory Mediators ◽  
Raw264.7 Macrophages ◽  
Potential Mediator ◽  
Obese Subjects

Obesity is associated with a state of chronic low-grade inflammation, which contributes to insulin resistance and type 2 diabetes. However, the molecular mechanisms that link obesity to inflammation are not fully understood. Follistatin-like 1 (FSTL1) is a novel proinflammatory cytokine that is expressed in adipose tissue and secreted by preadipocytes/adipocytes. We aimed to test whether FSTL1 could have a role in obesity-induced inflammation and insulin resistance. It was found that FSTL1 expression was markedly decreased during differentiation of 3T3-L1 preadipocytes but reinduced by TNF-α. Furthermore, a significant increase in FSTL1 levels was observed in adipose tissue of obese ob/ob mice, as well as in serum of overweight/obese subjects. Mechanistic studies revealed that FSTL1 induced inflammatory responses in both 3T3-L1 adipocytes and RAW264.7 macrophages. The expression of proinflammatory mediators including IL-6, TNF-α, and MCP-1 was upregulated by recombinant FSTL1 in a dose-dependent manner, paralleled with activation of the IKKβ-NFκB and JNK signaling pathways in the two cell lines. Moreover, FSTL1 impaired insulin signaling in 3T3-L1 adipocytes, as revealed by attenuated phosphorylation of both Akt and IRS-1 in response to insulin stimulation. Together, our results suggest that FSTL1 is a potential mediator of inflammation and insulin resistance in obesity.

scholarly journals Adipose tissue inflammation and metabolic dysfunction: a clinical perspective

2013 ◽  
Vol 15 (1) ◽  
Author(s):  
Charmaine S. Tam ◽  
Leanne M. Redman
Keyword(s):  
Insulin Resistance ◽  
Adipose Tissue ◽  
Low Grade ◽  
Metabolic Dysfunction ◽  
Adipose Tissue Inflammation ◽  
Tissue Inflammation ◽  
Proinflammatory Mediators ◽  
Low Grade Inflammation

AbstractObesity is characterized by a state of chronic low-grade inflammation due to increased immune cells, specifically infiltrated macrophages into adipose tissue, which in turn secrete a range of proinflammatory mediators. This nonselective low-grade inflammation of adipose tissue is systemic in nature and can impair insulin signaling pathways, thus, increasing the risk of developing insulin resistance and type 2 diabetes. The aim of this review is to provide an update on clinical studies examining the role of adipose tissue in the development of obesity-associated complications in humans. We will discuss adipose tissue inflammation during different scenarios of energy imbalance and metabolic dysfunction including obesity and overfeeding, weight loss by calorie restriction or bariatric surgery, and conditions of insulin resistance (diabetes, polycystic ovarian syndrome).

scholarly journals Review: Obesity and COVID-19: A Detrimental Intersection

2021 ◽  
Vol 12 ◽  
Author(s):  
Maria Alessandra Gammone ◽  
Nicolantonio D’Orazio
Keyword(s):  
Adipose Tissue ◽  
Visceral Fat ◽  
Molecular Mechanisms ◽  
Therapeutic Potential ◽  
Fat Distribution ◽  
Low Grade ◽  
Viral Spread ◽  
Obese Subjects ◽  
Adipose Inflammation ◽  
Phenotypic Shift

Obesity has been recognized as an independent risk factor for critical illness and major severity in subjects with coronavirus disease 2019 (COVID-19). The role of fat distribution, particularly visceral fat (often linked to metabolic abnormalities), is still unclear. The adipose tissue represents a direct source of cytokines responsible for the pathological modifications occurring within adipose tissue in obese subjects. Adipokines are a crucial connection between metabolism and immune system: their dysregulation in obesity contributes to chronic low-grade systemic inflammation and metabolic comorbidities. Therefore the increased amount of visceral fat can lead to a proinflammatory phenotypic shift. This review analyzes the interrelation between obesity and COVID-19 severity, as well as the cellular key players and molecular mechanisms implicated in adipose inflammation, investigating if adipose tissue can constitute a reservoir for viral spread, and contribute to immune activation and cytokines storm. Targeting the underlying molecular mechanisms might have therapeutic potential in the management of obesity-related complications in COVID-19 patients.

scholarly journals Caragana rosea Turcz Methanol Extract Inhibits Lipopolysaccharide-Induced Inflammatory Responses by Suppressing the TLR4/NF-κB/IRF3 Signaling Pathways

Molecules ◽  
2021 ◽  
Vol 26 (21) ◽  
pp. 6660
Author(s):  
Ankita Mitra ◽  
Akash Ahuja ◽  
Laily Rahmawati ◽  
Han Gyung Kim ◽  
Byoung Young Woo ◽  
...  
Keyword(s):  
Signaling Pathways ◽  
Molecular Mechanisms ◽  
Methanol Extract ◽  
Inflammatory Responses ◽  
Eastern China ◽  
Mrna Levels ◽  
Dependent Manner ◽  
Concentration Dependent Manner ◽  
Raw264.7 Macrophages ◽  
Anti Inflammatory

Caragana rosea Turcz, which belongs to the Leguminosae family, is a small shrub found in Northern and Eastern China that is known to possess anti-inflammatory properties and is used to treat fever, asthma, and cough. However, the underlying molecular mechanisms of its anti-inflammatory effects are unknown. Therefore, we used lipopolysaccharide (LPS) in RAW264.7 macrophages to investigate the molecular mechanisms that underlie the anti-inflammatory activities of a methanol extract of Caragana rosea (Cr-ME). We showed that Cr-ME reduced the production of nitric oxide (NO) and mRNA levels of iNOS, TNF-α, and IL-6 in a concentration-dependent manner. We also found that Cr-ME blocked MyD88- and TBK1-induced NF-κB and IRF3 promoter activity, suggesting that it affects multiple targets. Moreover, Cr-ME reduced the phosphorylation levels of IκBα, IKKα/β and IRF3 in a time-dependent manner and regulated the upstream NF-κB proteins Syk and Src, and the IRF3 protein TBK1. Upon overexpression of Src and TBK1, Cr-ME stimulation attenuated the phosphorylation of the NF-κB subunits p50 and p65 and IRF3 signaling. Together, our results suggest that the anti-inflammatory activity of Cr-ME occurs by inhibiting the NF-κB and IRF3 signaling pathways.

scholarly journals The Effects of Poncirus fructus on Insulin Resistance and the Macrophage-Mediated Inflammatory Response in High Fat Diet-Induced Obese Mice

2019 ◽  
Vol 20 (12) ◽  
pp. 2858 ◽  
Author(s):  
Mia Kim ◽  
Mi Hyeon Seol ◽  
Byung-Cheol Lee
Keyword(s):  
Gene Expression ◽  
Insulin Resistance ◽  
Adipose Tissue ◽  
Kupffer Cells ◽  
High Fat Diet ◽  
Inflammatory Responses ◽  
Low Grade ◽  
Obese Mice ◽  
High Fat ◽  
Epididymal Fat

Obesity is a chronic low-grade inflammatory condition in which hypertrophied adipocytes and adipose tissue immune cells, mainly macrophages, contribute to increased circulating levels of proinflammatory cytokines. Obesity-associated chronic low-grade systemic inflammation is considered a focal point and a therapeutic target in insulin resistance and metabolic diseases. We evaluate the effect of Poncirus fructus (PF) on insulin resistance and its mechanism based on inflammatory responses in high-fat diet (HFD)-induced obese mice. Mice were fed an HFD to induce obesity and then administered PF. Body weight, epididymal fat and liver weight, glucose, lipid, insulin, and histologic characteristics were evaluated to determine the effect of PF on insulin resistance by analyzing the proportion of macrophages in epididymal fat and liver and measured inflammatory gene expression. PF administration significantly decreased the fasting and postprandial glucose, fasting insulin, HOMA-IR, total-cholesterol, triglycerides, and low-density lipoprotein cholesterol levels. The epididymal fat tissue and liver showed a significant decrease of fat accumulation in histological analysis. PF significantly reduced the number of adipose tissue macrophages (ATMs), F4/80+ Kupffer cells, and CD68+ Kupffer cells, increased the proportion of M2 phenotype macrophages, and decreased the gene expression of inflammatory cytokines. These results suggest that PF could be used to improve insulin resistance through modulation of macrophage-mediated inflammation and enhance glucose and lipid metabolism.

scholarly journals Human Adipose Tissue Macrophages Are Enhanced but Changed to an Anti-Inflammatory Profile in Obesity

2014 ◽  
Vol 2014 ◽  
pp. 1-10 ◽  
Author(s):  
Karen Fjeldborg ◽  
Steen B. Pedersen ◽  
Holger J. Møller ◽  
Tore Christiansen ◽  
Marianne Bennetzen ◽  
...  
Keyword(s):  
Insulin Resistance ◽  
Adipose Tissue ◽  
Human Adipose Tissue ◽  
Multivariate Regression Analysis ◽  
Low Grade ◽  
Macrophage Marker ◽  
Adipose Tissue Macrophages ◽  
Obese Subjects ◽  
Anti Inflammatory ◽  
Inflammatory Profile

Objective. Adipose tissue (AT) macrophages are increased in obesity and associated with low grade inflammation. We aimed to characterize the phenotype of AT macrophages in humans in relation to obesity and insulin resistance.Design. Gene-expression levels of general macrophage markers (CD68 and CD14), proinflammatory markers/M1 (TNF-α, MCP-1, and IL-6), and anti-inflammatory markers/M2 (CD163, CD206, and IL-10) were determined by RT-PCR in subcutaneous AT samples from lean and obese subjects. Insulin resistance was determined by HOMA-IR.Results. All the macrophage markers were elevated in the AT from obese compared to lean subjects (P<0.001). To determine the phenotype of the macrophages the level of CD14 was used to adjust the total number of macrophages. The relative expression of CD163 and IL-10 was elevated, and TNF-αand IL-6 were reduced in AT from obese subjects (allP<0.05). In a multivariate regression analysis CD163 was the only macrophage marker significantly associated with HOMA-IR (β: 0.57;P<0.05). Conclusion. Obesity is associated with elevated numbers of macrophages in the AT. Unexpectedly, the macrophages change phenotype by obesity, with a preponderance of M2 and a decrement of M1 markers in AT from obese subjects. Moreover, CD163 was the only macrophage marker associated with HOMA-IR after multiple adjustments.

scholarly journals Obese Adipose Tissue Secretion Induces Inflammation in Preadipocytes: Role of Toll-Like Receptor-4

Nutrients ◽  
2020 ◽  
Vol 12 (9) ◽  
pp. 2828 ◽  
Author(s):  
Mariana Renovato-Martins ◽  
Catharina Moreira-Nunes ◽  
Georgia C. Atella ◽  
Christina Barja-Fidalgo ◽  
João Alfredo de Moraes
Keyword(s):  
Adipose Tissue ◽  
Nuclear Translocation ◽  
Low Grade ◽  
Dependent Manner ◽  
Oxygen Species ◽  
Toll Like Receptor ◽  
Toll Like Receptor 4 ◽  
Proinflammatory Mediators ◽  
Low Grade Inflammation

In obesity, the dysfunctional adipose tissue (AT) releases increased levels of proinflammatory adipokines such as TNFα, IL-6, and IL-1β and free fatty acids (FFAs), characterizing a chronic, low-grade inflammation. Whilst FFAs and proinflammatory adipokines are known to elicit an inflammatory response within AT, their relative influence upon preadipocytes, the precursors of mature adipocytes, is yet to be determined. Our results demonstrated that the conditioned medium (CM) derived from obese AT was rich in FFAs, which guided us to evaluate the role of TLR4 in the induction of inflammation in preadipocytes. We observed that CM derived from obese AT increased reactive oxygen species (ROS) levels and NF-ĸB nuclear translocation together with IL-6, TNFα, and IL-1β in 3T3-L1 cells in a TLR4-dependent manner. Furthermore, TLR4 signaling was involved in the increased expression of C/EBPα together with the release of leptin, adiponectin, and proinflammatory mediators, in response to the CM derived from obese AT. Our results suggest that obese AT milieu secretes lipokines, which act in a combined paracrine/autocrine manner, inducing inflammation in preadipocytes via TLR4 and ROS, thus creating a paracrine loop that facilitates the differentiation of adipocytes with a proinflammatory profile.

Innate immunity orchestrates adipose tissue homeostasis

2017 ◽  
Vol 31 (1) ◽  
Author(s):  
Yi-Wei Lin ◽  
Li-Na Wei
Keyword(s):  
Insulin Resistance ◽  
Innate Immunity ◽  
Adipose Tissue ◽  
Inflammatory Responses ◽  
Inflammatory Cells ◽  
Whole Body ◽  
M2 Macrophage ◽  
Low Grade ◽  
Metabolic Complications ◽  
M1 Macrophage

AbstractObesity is strongly associated with multiple diseases including insulin resistance, type 2 diabetes, cardiovascular diseases, fatty liver disease, neurodegenerative diseases and cancers, etc. Adipose tissue (AT), mainly brown AT (BAT) and white AT (WAT), is an important metabolic and endocrine organ that maintains whole-body homeostasis. BAT contributes to non-shivering thermogenesis in a cold environment; WAT stores energy and produces adipokines that fine-tune metabolic and inflammatory responses. Obesity is often characterized by over-expansion and inflammation of WAT where inflammatory cells/mediators are abundant, especially pro-inflammatory (M1) macrophages, resulting in chronic low-grade inflammation and leading to insulin resistance and metabolic complications. Macrophages constitute the major component of innate immunity and can be activated as a M1 or M2 (anti-inflammatory) phenotype in response to environmental stimuli. Polarized M1 macrophage causes AT inflammation, whereas polarized M2 macrophage promotes WAT remodeling into the BAT phenotype, also known as WAT browning/beiging, which enhances insulin sensitivity and metabolic health. This review will discuss the regulation of AT homeostasis in relation to innate immunity.

scholarly journals Obesity and lung inflammation

2010 ◽  
Vol 108 (3) ◽  
pp. 722-728 ◽  
Author(s):  
Peter Mancuso
Keyword(s):  
Adipose Tissue ◽  
Lung Disease ◽  
Inflammatory Responses ◽  
Acute Phase Proteins ◽  
Pulmonary Inflammation ◽  
Therapeutic Interventions ◽  
Low Grade ◽  
Tissue Mass ◽  
Proinflammatory Mediators ◽  
Increased Risk

The prevalence of obesity has increased dramatically worldwide, predisposing individuals to an increased risk of morbidity and mortality due to cardiovascular disease and type 2 diabetes. Less recognized is the fact that obesity may play a significant role in the pathogenesis of pulmonary diseases through mechanisms that may involve proinflammatory mediators produced in adipose tissue that contribute to a low-grade state of systemic inflammation. In animal models, inflammatory responses in the lung have been shown to influence the production of the adipocytokines, leptin and adiponectin, cytokines, acute phase proteins, and other mediators produced by adipose tissue that may participate in immune responses of the lung. An increased adipose tissue mass may also influence susceptibility to pulmonary infections, enhance pulmonary inflammation associated with environmental exposures, and exacerbate airway obstruction in preexisting lung disease. An increased understanding of the mechanisms by which obesity influences pulmonary inflammation may facilitate the development of novel therapeutic interventions for the treatment of lung disease.

scholarly journals Novel Role of Endogenous Catalase in Macrophage Polarization in Adipose Tissue

2016 ◽  
Vol 2016 ◽  
pp. 1-14 ◽  
Author(s):  
Ye Seul Park ◽  
Md Jamal Uddin ◽  
Lingjuan Piao ◽  
Inah Hwang ◽  
Jung Hwa Lee ◽  
...  
Keyword(s):  
Oxidative Stress ◽  
Insulin Resistance ◽  
Adipose Tissue ◽  
Inflammatory Responses ◽  
Macrophage Polarization ◽  
Alternative Activation ◽  
Phenotypic Switch ◽  
Raw264.7 Macrophages ◽  
Adipose Tissue Macrophages

Macrophages are important components of adipose tissue inflammation, which results in metabolic diseases such as insulin resistance. Notably, obesity induces a proinflammatory phenotypic switch in adipose tissue macrophages, and oxidative stress facilitates this switch. Thus, we examined the role of endogenous catalase, a key regulator of oxidative stress, in the activity of adipose tissue macrophages in obese mice. Catalase knockout (CKO) exacerbated insulin resistance, amplified oxidative stress, and accelerated macrophage infiltration into epididymal white adipose tissue in mice on normal or high-fat diet. Interestingly, catalase deficiency also enhanced classical macrophage activation (M1) and inflammation but suppressed alternative activation (M2) regardless of diet. Similarly, pharmacological inhibition of catalase activity using 3-aminotriazole induced the same phenotypic switch and inflammatory response in RAW264.7 macrophages. Finally, the same phenotypic switch and inflammatory responses were observed in primary bone marrow-derived macrophages from CKO mice. Taken together, the data indicate that endogenous catalase regulates the polarization of adipose tissue macrophages and thereby inhibits inflammation and insulin resistance.

scholarly journals Adipokines as Drug Targets in Diabetes and Underlying Disturbances

2015 ◽  
Vol 2015 ◽  
pp. 1-11 ◽  
Author(s):  
Vinícius Andrade-Oliveira ◽  
Niels O.S. Câmara ◽  
Pedro M. Moraes-Vieira
Keyword(s):  
Insulin Resistance ◽  
Adipose Tissue ◽  
Drug Targets ◽  
Inflammatory Responses ◽  
Inflammatory Diseases ◽  
Low Grade ◽  
Adipose Tissue Inflammation ◽  
Tissue Inflammation ◽  
Therapeutic Implications ◽  
Insulin Resistant

Diabetes and obesity are worldwide health problems. White fat dynamically participates in hormonal and inflammatory regulation. White adipose tissue is recognized as a multifactorial organ that secretes several adipose-derived factors that have been collectively termed “adipokines.” Adipokines are pleiotropic molecules that gather factors such as leptin, adiponectin, visfatin, apelin, vaspin, hepcidin, RBP4, and inflammatory cytokines, including TNF and IL-1β, among others. Multiple roles in metabolic and inflammatory responses have been assigned to these molecules. Several adipokines contribute to the self-styled “low-grade inflammatory state” of obese and insulin-resistant subjects, inducing the accumulation of metabolic anomalies within these individuals, including autoimmune and inflammatory diseases. Thus, adipokines are an interesting drug target to treat autoimmune diseases, obesity, insulin resistance, and adipose tissue inflammation. The aim of this review is to present an overview of the roles of adipokines in different immune and nonimmune cells, which will contribute to diabetes as well as to adipose tissue inflammation and insulin resistance development. We describe how adipokines regulate inflammation in these diseases and their therapeutic implications. We also survey current attempts to exploit adipokines for clinical applications, which hold potential as novel approaches to drug development in several immune-mediated diseases.

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