TNFα Mediates Inflammation-Induced Effects on PPARG Splicing in Adipose Tissue and Mesenchymal Precursor Cells

Low-grade chronic inflammation and reduced differentiation capacity are hallmarks of hypertrophic adipose tissue (AT) and key contributors of insulin resistance. We identified PPARGΔ5 as a dominant-negative splicing isoform overexpressed in the AT of obese/diabetic patients able to impair adipocyte differentiation and PPARγ activity in hypertrophic adipocytes. Herein, we investigate the impact of macrophage-secreted pro-inflammatory factors on PPARG splicing, focusing on PPARGΔ5. We report that the epididymal AT of LPS-treated mice displays increased PpargΔ5/cPparg ratio and reduced expression of Pparg-regulated genes. Interestingly, pro-inflammatory factors secreted from murine and human pro-inflammatory macrophages enhance the PPARGΔ5/cPPARG ratio in exposed adipogenic precursors. TNFα is identified herein as factor able to alter PPARG splicing—increasing PPARGΔ5/cPPARG ratio—through PI3K/Akt signaling and SRp40 splicing factor. In line with in vitro data, TNFA expression is higher in the SAT of obese (vs. lean) patients and positively correlates with PPARGΔ5 levels. In conclusion, our results indicate that inflammatory factors secreted by metabolically-activated macrophages are potent stimuli that modulate the expression and splicing of PPARG. The resulting imbalance between canonical and dominant negative isoforms may crucially contribute to impair PPARγ activity in hypertrophic AT, exacerbating the defective adipogenic capacity of precursor cells.

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Decreased TLR3 in Hyperplastic Adipose Tissue, Blood and Inflamed Adipocytes is Related to Metabolic Inflammation

Cellular Physiology and Biochemistry ◽

10.1159/000495487 ◽

2018 ◽

Vol 51 (3) ◽

pp. 1051-1068 ◽

Cited By ~ 7

Author(s):

Jèssica Latorre ◽

José M. Moreno-Navarrete ◽

Mónica Sabater ◽

Maria Buxo ◽

José I. Rodriguez-Hermosa ◽

...

Keyword(s):

Weight Loss ◽

Adipose Tissue ◽

Low Grade ◽

Metabolic Inflammation ◽

Fat Depots ◽

Acute Surgery ◽

Obese Subjects ◽

Anti Inflammatory ◽

The Impact

Background/Aims: Obesity is characterized by the immune activation that eventually dampens insulin sensitivity and changes metabolism. This study explores the impact of different inflammatory/ anti-inflammatory paradigms on the expression of toll-like receptors (TLR) found in adipocyte cultures, adipose tissue, and blood. Methods: We evaluated by real time PCR the impact of acute surgery stress in vivo (adipose tissue) and macrophages (MCM) in vitro (adipocytes). Weight loss was chosen as an anti-inflammatory model, so TLR were analyzed in fat samples collected before and after bariatric surgery-induced weight loss. Associations with inflammatory and metabolic parameters were analyzed in non-obese and obese subjects, in parallel with gene expression measures taken in blood and isolated adipocytes/ stromal-vascular cells (SVC). Treatments with an agonist of TLR3 were conducted in human adipocyte cultures under normal conditions and upon conditions that simulated the chronic low-grade inflammatory state of obesity. Results: Surgery stress raised TLR1 and TLR8 in subcutaneous (SAT), and TLR2 in SAT and visceral (VAT) adipose tissue, while decreasing VAT TLR3 and TLR4. MCM led to increased TLR2 and diminished TLR3, TLR4, and TLR5 expressions in human adipocytes. The anti-inflammatory impact of weight loss was concomitant with decreased TLR1, TLR3, and TLR8 in SAT. Cross-sectional associations confirmed increased V/ SAT TLR1 and TLR8, and decreased TLR3 in obese patients, as compared with non-obese subjects. As expected, TLR were predominant in SVC and adipocyte precursor cells, even though expression of all of them but TLR8 (very low levels) was also found in ex vivo isolated and in vitro differentiated adipocytes. Among SVC, CD14+ macrophages showed increased TLR1, TLR2, and TLR7, but decreased TLR3 mRNA. The opposite patterns shown for TLR2 and TLR3 in V/ SAT, SVC, and inflamed adipocytes were observed in blood as well, being TLR3 more likely linked to lymphocyte instead of neutrophil counts. On the other hand, decreased TLR3 in adipocytes challenged with MCM dampened lipogenesis and the inflammatory response to Poly(I:C). Conclusion: Functional variations in the expression of TLR found in blood and hypertrophied fat depots, namely decreased TLR3 in lymphocytes and inflamed adipocytes, are linked to metabolic inflammation.

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Metformin and Pioglitazone Reduce Gene Expression of Inflammatory Factors in Insulin Resistant and Hypertrophied Adipocytes

Iranian journal of diabetes and obesity ◽

10.18502/ijdo.v12i4.5185 ◽

2021 ◽

Author(s):

Zahra Malekpour-Dehkordi ◽

Javad Mohiti-Ardekani ◽

Yousof Naghiaee ◽

Shahram Teimourian ◽

Mahdie Hemati ◽

...

Keyword(s):

Gene Expression ◽

Insulin Resistance ◽

Adipose Tissue ◽

Transforming Growth Factor ◽

Inflammatory Factors ◽

P Value ◽

Low Grade ◽

Insulin Resistant ◽

Reduce Gene Expression

Objective: In obesity, chronic low grade inflammation, created by induction of pro-inflammatory markers, causes adipocyte dysfunction in adipose tissue. Adipocytes dysfunction is associated with various diseases including insulin resistance and obesity. In obesity, inflammatory factors such as osteopontin (OPN), angiopoietin-like protein 2 (Angptl2) and transforming growth factor-β (TGF-β) are induced in adipose tissue. Metformin and pioglitazone that are used to modulate inflammation, but the relevant mechanism is poorly understood. This study aimed to investigate the effect of metformin and pioglitazone as anti-diabetic drugs, on gene expression of osteopontin, Angptl2 and TGF-β as inflammatory factors in insulin resistance and hypertrophied adipocyte in 3T3-L1 cell line model in vitro. Materials and Methods: In this experimental research, we differentiated3T3-L1 preadipocytes to adipocytes. The adipocytes treated in insulin resistance and hypertrophied conditions with metformin and pioglitazone and assayed gene expression of OPN, Angptl2 and TGF-β by Real-Time PCR. Data was analyzed by SPSS statistic software. Results: The results showed that expression of OPN, Angptl2, and TGF-β were increased significantly over 2-fold (P-value< 0.05) in insulin resistance and hypertrophied adipocytes compared to normal adipocytes. Pre- and co-treatment with metformin and pioglitazone led to reduced expression of Angptl2 and TGF-β. Only metformin significantly reduced the expression of Angptl2, TGF-β and OPN in hypertrophied adipocyte. Conclusion: These results support the proposal that metformin and pioglitazone reduce gene expression of inflammatory factors in insulin resistant and hypertrophied adipocytes.

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Chemotactic cytokines, obesity and type 2 diabetes:in vivoandin vitroevidence for a possible causal correlation?

Proceedings of The Nutrition Society ◽

10.1017/s0029665109990218 ◽

2009 ◽

Vol 68 (4) ◽

pp. 378-384 ◽

Cited By ~ 41

Author(s):

Henrike Sell ◽

Jürgen Eckel

Keyword(s):

Insulin Resistance ◽

Adipose Tissue ◽

Low Grade ◽

Obese Patients ◽

Tissue Mass ◽

Tissue Biology ◽

Wide Range ◽

Adipose Tissue Mass

A strong causal link between increased adipose tissue mass and insulin resistance in tissues such as liver and skeletal muscle exists in obesity-related disorders such as type 2 diabetes. Increased adipose tissue mass in obese patients and patients with diabetes is associated with altered secretion of adipokines, which also includes chemotactic proteins. Adipose tissue releases a wide range of chemotactic proteins including many chemokines and chemerin, which are interesting targets for adipose tissue biology and for biomedical research in obesity and obesity-related diseases. This class of adipokines may be directly linked to a chronic state of low-grade inflammation and macrophage infiltration in adipose tissue, a concept intensively studied in adipose tissue biology in recent years. The inflammatory state of adipose tissue in obese patients may be the most important factor linking increased adipose tissue mass to insulin resistance. Furthermore, chemoattractant adipokines may play an important role in this situation, as many of these proteins possess biological activity beyond the recruitment of immune cells including effects on adipogenesis and glucose homeostasis in insulin-sensitive tissues. The present review provides a summary of experimental evidence of the role of adipose tissue-derived chemotactic cytokines and their function in insulin resistancein vivoandin vitro.

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Human Adipose-Derived Stromal/Stem Cell Culture and Analysis Methods for Adipose Tissue Modeling In Vitro: A Systematic Review

Cells ◽

10.3390/cells10061378 ◽

2021 ◽

Vol 10 (6) ◽

pp. 1378

Author(s):

Peyton Gibler ◽

Jeffrey Gimble ◽

Katie Hamel ◽

Emma Rogers ◽

Michael Henderson ◽

...

Keyword(s):

Systematic Review ◽

Adipose Tissue ◽

Drug Discovery ◽

3D Culture ◽

Human Adipose Tissue ◽

Culture Methods ◽

Adipose Tissue Engineering ◽

The Impact

Human adipose-derived stromal/stem cells (hASC) are widely used for in vitro modeling of physiologically relevant human adipose tissue. These models are useful for the development of tissue constructs for soft tissue regeneration and 3-dimensional (3D) microphysiological systems (MPS) for drug discovery. In this systematic review, we report on the current state of hASC culture and assessment methods for adipose tissue engineering using 3D MPS. Our search efforts resulted in the identification of 184 independent records, of which 27 were determined to be most relevant to the goals of the present review. Our results demonstrate a lack of consensus on methods for hASC culture and assessment for the production of physiologically relevant in vitro models of human adipose tissue. Few studies have assessed the impact of different 3D culture conditions on hASC adipogenesis. Additionally, there has been a limited use of assays for characterizing the functionality of adipose tissue in vitro. Results from this study suggest the need for more standardized culture methods and further analysis on in vitro tissue functionality. These will be necessary to validate the utility of 3D MPS as an in vitro model to reduce, refine, and replace in vivo experiments in the drug discovery regulatory process.

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High Glucose-Mediated Cytokine Regulation in Gingival Fibroblasts and THP-1 Macrophage: a Possible Mechanism of Severe Periodontitis with Diabetes

Cellular Physiology and Biochemistry ◽

10.1159/000494481 ◽

2018 ◽

Vol 50 (3) ◽

pp. 973-986 ◽

Cited By ~ 4

Author(s):

Jung-Hwan Lew ◽

Koji Naruishi ◽

Yukari Kajiura ◽

Yasufumi Nishikawa ◽

Takahisa Ikuta ◽

...

Keyword(s):

High Glucose ◽

Gingival Crevicular Fluid ◽

In Vitro Study ◽

Inflammatory Factors ◽

Diabetic Patients ◽

Gingival Fibroblasts ◽

Cross Sectional ◽

Periodontal Tissues ◽

Severe Periodontitis

Background/Aims: Diabetic patients are susceptible to severe periodontitis, but the precise mechanism is not fully understood. Aim of this study was to explore the biological pathogenesis of severe periodontitis in diabetic patients focusing on the crosstalk of human gingival fibroblasts (HGFs) and macrophages. Methods: A total of 70 periodontitis patients with or without diabetes mellitus (DM) were enrolled, and the statistical relationships of diabetic conditions to the periodontal inflammatory parameters were examined by cross-sectional study. In in vitro study, HGFs cell line CRL-2014® (ATCC) and differentiated THP-1 macrophages were cultured with normal glucose (NG: 5.5 mM) or high glucose (HG: 25 mM) condition, and treated with indicated inflammatory factors such as calprotectin (CPT), interleukin (IL)-1β and IL-6. To examine the effects of HG on soluble IL-6 receptor (sIL-6R) production in THP-1 macrophages, the supernatants were collected and the sIL-6R levels were measured by ELISA. To examine the effects of HG on IL-1β or IL-6-induced matrix metalloproteinase (MMPs) production in HGFs, the supernatants were collected. Levels of MMP-1 and tissue inhibitor of MMP-1 (TIMP-1) were measured by ELISA. Finally, after conditioned medium (CM) from THP-1 macrophages cultured with NG or HG conditions was collected, HGFs were treated with the CM. The supernatants were collected 24 hours later and the levels of MMP-1 and TIMP-1 were measured. To examine the specific effects of IL-1β contained in CM on MMP-1 and TIMP-1 production in HGFs, IL-1 receptor antagonist (IL-1ra) was used. Results: There were statistical correlation between IL-1β and sIL-6R levels in gingival crevicular fluid (GCF) and HbA1c in periodontitis patients with DM (IL-1β: P=0.035, sIL-6R: P=0.040). HG and CPT significantly induced sIL-6R production in THP-1 macrophages. HG significantly enhanced IL-1β or IL-6/sIL-6R-induced MMP-1 production in HGFs. The increase of MMP-1 by both IL-1β and IL-6/sIL-6R was significantly inhibited by specific ERK or IκB inhibitors. Corresponding to the regulation of MMP-1 production, HG condition increased the phosphorylation of p44/42 MAPK and IκBα in HGFs treated with IL-1β or IL-6/sIL-6R. Finally, MMP-1 production in HGFs cultured with HG increased significantly by CM from THP-1 macrophages cultured with HG. The induction of MMP-1 by the CM from THP-1 macrophages cultured with HG was significantly inhibited by dose dependent of IL-1ra in HGFs cultured with HG. Conclusion: Diabetic conditions such as HG induce IL-1β and sIL-6R production from macrophages in inflammatory periodontal tissues and may exacerbate the periodontitis synergistically via MMP-1 production from HGFs.

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Stabilization but no functional influence of HIF-1α expression in the intestinal epithelium during Salmonella Typhimurium infection

Infection and Immunity ◽

10.1128/iai.00222-21 ◽

2022 ◽

Author(s):

Laura Robrahn ◽

Aline Dupont ◽

Sandra Jumpertz ◽

Kaiyi Zhang ◽

Christian H. Holland ◽

...

Keyword(s):

Gene Expression ◽

Intestinal Epithelium ◽

Bacterial Infections ◽

Inflammatory Diseases ◽

Protein Stabilization ◽

Inflammatory Factors ◽

Intestinal Epithelial ◽

Data Set ◽

The Impact

The hypoxia-inducible transcription factor 1 (HIF-1) has been shown to enhance microbial killing and to ameliorate the course of bacterial infections. While the impact of HIF-1 on inflammatory diseases of the gut has been studied intensively, its function in bacterial infections of the gastrointestinal tract remains largely elusive. With the help of a publicly available gene expression data set, we could infer significant activation of HIF-1 after oral infection of mice with Salmonella Typhimurium. Immunohistochemistry and western blot analysis confirmed marked HIF-1α protein stabilization, especially in the intestinal epithelium. This prompted us to analyze conditional Hif1a -deficient mice to examine cell type-specific functions of HIF-1 in this model. Our results demonstrate enhanced non-canonical induction of HIF-1 activity upon Salmonella infection in the intestinal epithelium as well as in macrophages. Surprisingly, Hif1a deletion in intestinal epithelial cells did not impact on inflammatory gene expression, bacterial spread or disease outcome. In contrast, Hif1a deletion in myeloid cells enhanced intestinal Cxcl2 expression and reduced the cecal Salmonella load. In vitro , HIF-1α-deficient macrophages showed an overall impaired transcription of mRNA encoding pro-inflammatory factors, however, intracellular survival of Salmonella was not impacted by HIF-1α deficiency.

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NLRP3 Inflammasome Activation in Adipose Tissues and Its Implications on Metabolic Diseases

International Journal of Molecular Sciences ◽

10.3390/ijms21114184 ◽

2020 ◽

Vol 21 (11) ◽

pp. 4184 ◽

Cited By ~ 1

Author(s):

Kelvin Ka-Lok Wu ◽

Samson Wing-Ming Cheung ◽

Kenneth King-Yip Cheng

Keyword(s):

Adipose Tissue ◽

Nlrp3 Inflammasome ◽

Metabolic Disorders ◽

Immune Cell ◽

Diabetic Patients ◽

Inflammasome Activation ◽

Low Grade ◽

Adipose Tissues ◽

Adipose Tissue Dysfunction ◽

Nlrp3 Inflammasome Activation

Adipose tissue is an active endocrine and immune organ that controls systemic immunometabolism via multiple pathways. Diverse immune cell populations reside in adipose tissue, and their composition and immune responses vary with nutritional and environmental conditions. Adipose tissue dysfunction, characterized by sterile low-grade chronic inflammation and excessive immune cell infiltration, is a hallmark of obesity, as well as an important link to cardiometabolic diseases. Amongst the pro-inflammatory factors secreted by the dysfunctional adipose tissue, interleukin (IL)-1β, induced by the NLR family pyrin domain-containing 3 (NLRP3) inflammasome, not only impairs peripheral insulin sensitivity, but it also interferes with the endocrine and immune functions of adipose tissue in a paracrine manner. Human studies indicated that NLRP3 activity in adipose tissues positively correlates with obesity and its metabolic complications, and treatment with the IL-1β antibody improves glycaemia control in type 2 diabetic patients. In mouse models, genetic or pharmacological inhibition of NLRP3 activation pathways or IL-1β prevents adipose tissue dysfunction, including inflammation, fibrosis, defective lipid handling and adipogenesis, which in turn alleviates obesity and its related metabolic disorders. In this review, we summarize both the negative and positive regulators of NLRP3 inflammasome activation, and its pathophysiological consequences on immunometabolism. We also discuss the potential therapeutic approaches to targeting adipose tissue inflammasome for the treatment of obesity and its related metabolic disorders.

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Sensing through Non-Sensing Ocular Ion Channels

International Journal of Molecular Sciences ◽

10.3390/ijms21186925 ◽

2020 ◽

Vol 21 (18) ◽

pp. 6925

Author(s):

Meha Kabra ◽

Bikash Ranjan Pattnaik

Keyword(s):

Ion Channels ◽

Visual Processing ◽

Signal Transmission ◽

Dominant Negative ◽

Dominant Negative Effect ◽

Cone Dystrophy ◽

Wide Range ◽

The Impact

Ion channels are membrane-spanning integral proteins expressed in multiple organs, including the eye. In the eye, ion channels are involved in various physiological processes, like signal transmission and visual processing. A wide range of mutations have been reported in the corresponding genes and their interacting subunit coding genes, which contribute significantly to an array of blindness, termed ocular channelopathies. These mutations result in either a loss- or gain-of channel functions affecting the structure, assembly, trafficking, and localization of channel proteins. A dominant-negative effect is caused in a few channels formed by the assembly of several subunits that exist as homo- or heteromeric proteins. Here, we review the role of different mutations in switching a “sensing” ion channel to “non-sensing,” leading to ocular channelopathies like Leber’s congenital amaurosis 16 (LCA16), cone dystrophy, congenital stationary night blindness (CSNB), achromatopsia, bestrophinopathies, retinitis pigmentosa, etc. We also discuss the various in vitro and in vivo disease models available to investigate the impact of mutations on channel properties, to dissect the disease mechanism, and understand the pathophysiology. Innovating the potential pharmacological and therapeutic approaches and their efficient delivery to the eye for reversing a “non-sensing” channel to “sensing” would be life-changing.

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Inflammatory Microenvironment and Adipogenic Differentiation in Obesity: The Inhibitory Effect of Theobromine in a Model of Human Obesity In Vitro

Mediators of Inflammation ◽

10.1155/2019/1515621 ◽

2019 ◽

Vol 2019 ◽

pp. 1-10 ◽

Cited By ~ 12

Author(s):

Maria Pia Fuggetta ◽

Manuela Zonfrillo ◽

Cristina Villivà ◽

Enzo Bonmassar ◽

Giampiero Ravagnan

Keyword(s):

Adipose Tissue ◽

Proinflammatory Cytokines ◽

Adipogenic Differentiation ◽

Inhibitory Effect ◽

Low Grade ◽

Tissue Inflammation ◽

Inflammatory Microenvironment ◽

Adipocyte Cell ◽

Inflammatory State

Objective. Obesity is considered a clinic condition characterized by a state of chronic low-grade inflammation. The role of macrophages and adipocytokines in adipose tissue inflammation is in growing investigation. The physiopathological mechanisms involved in inflammatory state in obesity are not fully understood though the adipocytokines seem to characterize the biochemical link between obesity and inflammation. The aim of this work is to analyze the effect of theobromine, a methylxanthine present in the cocoa, on adipogenesis and on proinflammatory cytokines evaluated in a model of fat tissue inflammation in vitro. Methods. In order to mimic in vitro this inflammatory condition, we investigated the interactions between human-like macrophages U937 and human adipocyte cell lines SGBS. The effect of theobromine on in vitro cell growth, cell cycle, adipogenesis, and cytokines release in the supernatants has been evaluated. Results. Theobromine significantly inhibits the differentiation of preadipocytes in mature adipocytes and reduces the levels of proinflammatory cytokines as MCP-1 and IL-1β in the supernatants obtained by the mature adipocytes and macrophages interaction. Conclusion. Theobromine reduces adipogenesis and proinflammatory cytokines; these data suggest its potential therapeutic effect for treating obesity by control of macrophages infiltration in adipose tissue and inflammation.

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