scholarly journals The Molecular Mechanisms Underlying the Proinflammatory Actions of Thiazolidinediones in Human Macrophages

2007 ◽  
Vol 21 (8) ◽  
pp. 1756-1768 ◽  
Author(s):  
Julie M. Hall ◽  
Donald P. McDonnell
Keyword(s):  
Molecular Mechanisms ◽  
Inflammatory Responses ◽  
Inflammatory Diseases ◽  
Systemic Exposure ◽  
Receptor Subtype ◽  
Peroxisome Proliferator ◽  
Independent Manner ◽  
Subtype Specificity ◽  
Monocytes And Macrophages ◽  
Peroxisome Proliferator Activated Receptors

Abstract It is hypothesized that the antiinflammatory actions of peroxisome proliferator-activated receptors (PPARs) may explain the protective effect of these receptors in diabetes, atherosclerosis, cancer, and other inflammatory diseases. However, emerging evidence for proinflammatory activities of activated PPARs is concerning in light of new studies that associate PPAR modulators with an increased incidence of both cardiovascular events in humans and the sporadic formation of tumors in rodents. In an attempt to define the role of each PPAR subtype in inflammation, we made the unexpected observation that human PPARδ is a positive regulator of inflammatory responses in both monocytes and macrophages. Notably, TNFα-stimulated cells administered PPARδ agonists express and secrete elevated levels of inflammatory cytokines. Most surprising, however, was the finding that thiazolidinediones (TZDs) and other known PPARγ ligands display different degrees of proinflammatory activities in a PPARγ- and PPARα-independent manner via their ability to augment PPARδ signaling. A series of mechanistic studies revealed that TZDs, at clinically relevant concentrations, bind and activate the transcriptional activity of PPARδ. Collectively, these studies suggest that the observed proinflammatory and potentially deleterious effects of PPARγ ligands may be mediated through an off-target effect on PPARδ. These studies highlight the need for PPAR modulators with increased receptor subtype specificity. Furthermore, they suggest that differences in systemic exposure and consequently in the activation of PPARγ and PPARδ may explain why TZDs can exhibit both inflammatory and antiinflammatory activities in humans.

scholarly journals Molecular Mechanisms and Genome-Wide Aspects of PPAR Subtype Specific Transactivation

PPAR Research ◽  
2010 ◽  
Vol 2010 ◽  
pp. 1-12 ◽  
Author(s):  
Anne Bugge ◽  
Susanne Mandrup
Keyword(s):  
Energy Homeostasis ◽  
Target Gene ◽  
Molecular Mechanisms ◽  
Fat Metabolism ◽  
Special Focus ◽  
Peroxisome Proliferator ◽  
Subtype Specificity ◽  
Genome Wide ◽  
Peroxisome Proliferator Activated Receptors

The peroxisome proliferator-activated receptors (PPARs) are central regulators of fat metabolism, energy homeostasis, proliferation, and inflammation. The three PPAR subtypes, PPAR, /, and activate overlapping but also very different target gene programs. This review summarizes the insights into PPAR subtype-specific transactivation provided by genome-wide studies and discusses the recent advances in the understanding of the molecular mechanisms underlying PPAR subtype specificity with special focus on the regulatory role of AF-1.

scholarly journals Role of Peroxisome Proliferator-Activated Receptors in Inflammation Control

2004 ◽  
Vol 2004 (3) ◽  
pp. 156-166 ◽  
Author(s):  
Jihan Youssef ◽  
Mostafa Badr
Keyword(s):  
Inflammatory Responses ◽  
Inflammatory Diseases ◽  
Late Phase ◽  
Common Mechanism ◽  
Peroxisome Proliferator ◽  
Initiation Phase ◽  
Anti Inflammatory ◽  
Peroxisome Proliferator Activated Receptors

Peroxisome proliferator-activated receptors (PPARs) were discovered over a decade ago, and were classified as orphan members of the nuclear receptor superfamily. To date, three PPAR subtypes have been discovered and characterized (PPARα, β/δ, γ). Different PPAR subtypes have been shown to play crucial roles in important diseases and conditions such as obesity, diabetes, atherosclerosis, cancer, and fertility. Among the most studied roles of PPARs is their involvement in inflammatory processes. Numerous studies have revealed that agonists of PPARα and PPARγ exert anti-inflammatory effects both in vitro and in vivo. Using the carrageenan-induced paw edema model of inflammation, a recent study in our laboratories showed that these agonists hinder the initiation phase, but not the late phase of the inflammatory process. Furthermore, in the same experimental model, we recently also observed that activation of PPARδ exerted an anti-inflammatory effect. Despite the fact that exclusive dependence of these effects on PPARs has been questioned, the bulk of evidence suggests that all three PPAR subtypes, PPARα,δ,γ, play a significant role in controlling inflammatory responses. Whether these subtypes act via a common mechanism or are independent of each other remains to be elucidated. However, due to the intensity of research efforts in this area, it is anticipated that these efforts will result in the development of PPAR ligands as therapeutic agents for the treatment of inflammatory diseases.

scholarly journals Crosstalk between Peroxisome Proliferator-Activated Receptors andToll-Like Receptors: A Systematic Review

2019 ◽  
Vol 9 (1) ◽  
pp. 12-21 ◽  
Author(s):  
Nasim Dana ◽  
Golnaz Vaseghi ◽  
Shaghayegh Haghjooy-Javanmard
Keyword(s):  
Systematic Review ◽  
Immune System ◽  
Innate Immune System ◽  
Inflammatory Responses ◽  
Inflammatory Diseases ◽  
Innate Immune ◽  
Peroxisome Proliferator ◽  
Therapeutic Approaches ◽  
Disease Treatment ◽  
Peroxisome Proliferator Activated Receptors

As one of the four major families of pattern recognition receptors (PRRs), toll like receptors (TLRs)are crucial and important components of the innate immune system. Peroxisome proliferatoractivatedreceptors (PPARs) with three isoforms are transcription factors classified as a subfamilyof nuclear receptor proteins, and are of significant regulatory activity in cellular differentiation,development, metabolism, and tumorigenesis. It is well established that PPARs agonists displayanti-inflammatory effects through inhibition of the nuclear factor-kappa B (NF-κB) pathway, akey regulator of immune and inflammatory responses, in a sense that TLRs signaling pathwaysare mainly toward activation of NF-κB. Through a systematic review of previous studies, weaimed to address and clarify the reciprocal interaction between TLRs and PPARs in hope to findalternative therapeutic approaches for inflammatory diseases. Among the available scientificdatabase, 31 articles were selected for this review. A comprehensive review of this databaseconfirms the presence of a cross-talk between PPARs and TLRs, indicating that not onlyPPARs stimulation may affect the expression level of TLRs via several mechanisms leading tomodulating TLRs activities, but also TLRs have the potential to moderate the expression of PPARs.We, therefore, conclude that, as a key regulator of the innate immune system, the interactionbetween PPARs and TLRs is a potential therapeutic target in disease treatment.

scholarly journals Molecular Mechanisms of Obesity-Linked Cardiac Dysfunction: An Up-Date on Current Knowledge

Cells ◽  
2021 ◽  
Vol 10 (3) ◽  
pp. 629
Author(s):  
Jorge Gutiérrez-Cuevas ◽  
Ana Sandoval-Rodriguez ◽  
Alejandra Meza-Rios ◽  
Hugo Christian Monroy-Ramírez ◽  
Marina Galicia-Moreno ◽  
...  
Keyword(s):  
Oxidative Stress ◽  
Cardiac Dysfunction ◽  
Molecular Mechanisms ◽  
Current Knowledge ◽  
Peroxisome Proliferator ◽  
White Adipocyte ◽  
Peroxisome Proliferator Activated Receptors ◽  
And Oxidative Stress

Obesity is defined as excessive body fat accumulation, and worldwide obesity has nearly tripled since 1975. Excess of free fatty acids (FFAs) and triglycerides in obese individuals promote ectopic lipid accumulation in the liver, skeletal muscle tissue, and heart, among others, inducing insulin resistance, hypertension, metabolic syndrome, type 2 diabetes (T2D), atherosclerosis, and cardiovascular disease (CVD). These diseases are promoted by visceral white adipocyte tissue (WAT) dysfunction through an increase in pro-inflammatory adipokines, oxidative stress, activation of the renin-angiotensin-aldosterone system (RAAS), and adverse changes in the gut microbiome. In the heart, obesity and T2D induce changes in substrate utilization, tissue metabolism, oxidative stress, and inflammation, leading to myocardial fibrosis and ultimately cardiac dysfunction. Peroxisome proliferator-activated receptors (PPARs) are involved in the regulation of carbohydrate and lipid metabolism, also improve insulin sensitivity, triglyceride levels, inflammation, and oxidative stress. The purpose of this review is to provide an update on the molecular mechanisms involved in obesity-linked CVD pathophysiology, considering pro-inflammatory cytokines, adipokines, and hormones, as well as the role of oxidative stress, inflammation, and PPARs. In addition, cell lines and animal models, biomarkers, gut microbiota dysbiosis, epigenetic modifications, and current therapeutic treatments in CVD associated with obesity are outlined in this paper.

scholarly journals Unfulfilled Inflammatory Resolution: A Key Factor in the Pathogenesis of Psoriasis

2020 ◽  
Author(s):  
Zohreh Jadali
Keyword(s):  
Inflammatory Response ◽  
Chronic Inflammation ◽  
Molecular Mechanisms ◽  
Inflammatory Responses ◽  
Inflammatory Diseases ◽  
Relevant Literature ◽  
Regulatory Mechanisms ◽  
Immune Mediated ◽  
Key Factor ◽  
Inflammation Resolution

Recent literature has highlighted the importance of chronic inflammation in psoriasis pathogenesis. Non-resolving inflammation can trigger progressive tissue damage and inflammatory mediator release which in turn perpetuate the inflammatory cycle. Under normal conditions, inflammatory responses are tightly controlled through several mechanisms that restore normal tissue function and structure. Defects in regulatory mechanisms of the inflammatory response can result in persistent unresolved inflammation and further increases of inflammation. Therefore, this review focuses on defects in regulatory mechanisms of inflammatory responses that lead to uncontrolled chronic inflammation in psoriasis. Databases such as Pubmed Embase, ISI, and Iranian databases including Iranmedex, and SID were researched to identify relevant literature. The results of this review indicate that dysregulation of the inflammatory response may be a likely cause of various immune-mediated inflammatory disorders such as psoriasis. Based on current findings, advances in understanding the cellular and molecular mechanisms involved in inflammation resolution are not only improving our knowledge of the pathogenesis of chronic inflammatory diseases but also supporting the development of new therapeutic strategies.

scholarly journals Succinate Is an Inflammation-Induced Immunoregulatory Metabolite in Macrophages

Metabolites ◽  
2020 ◽  
Vol 10 (9) ◽  
pp. 372 ◽  
Author(s):  
Karl J. Harber ◽  
Kyra E. de Goede ◽  
Sanne G. S. Verberk ◽  
Elisa Meinster ◽  
Helga E. de Vries ◽  
...  
Keyword(s):  
Immune Responses ◽  
Immune Cells ◽  
Immune Cell ◽  
Inflammatory Responses ◽  
Inflammatory Diseases ◽  
Cell Phenotype ◽  
Independent Manner ◽  
Inflammatory Macrophages ◽  
Necrosis Factor

Immunometabolism revealed the crucial role of cellular metabolism in controlling immune cell phenotype and functions. Macrophages, key immune cells that support progression of numerous inflammatory diseases, have been well described as undergoing vast metabolic rewiring upon activation. The immunometabolite succinate particularly gained a lot of attention and emerged as a crucial regulator of macrophage responses and inflammation. Succinate was originally described as a metabolite that supports inflammation via distinct routes. Recently, studies have indicated that succinate and its receptor SUCNR1 can suppress immune responses as well. These apparent contradictory effects might be due to specific experimental settings and particularly the use of distinct succinate forms. We therefore compared the phenotypic and functional effects of distinct succinate forms and receptor mouse models that were previously used for studying succinate immunomodulation. Here, we show that succinate can suppress secretion of inflammatory mediators IL-6, tumor necrosis factor (TNF) and nitric oxide (NO), as well as inhibit Il1b mRNA expression of inflammatory macrophages in a SUCNR1-independent manner. We also observed that macrophage SUCNR1 deficiency led to an enhanced inflammatory response without addition of exogenous succinate. While our study does not reveal new mechanistic insights into how succinate elicits different inflammatory responses, it does indicate that the inflammatory effects of succinate and its receptor SUCNR1 in macrophages are clearly context dependent.

scholarly journals Association with Coregulators Is the Major Determinant Governing Peroxisome Proliferator-activated Receptor Mobility in Living Cells

2006 ◽  
Vol 282 (7) ◽  
pp. 4417-4426 ◽  
Author(s):  
Cicerone Tudor ◽  
Jérôme N. Feige ◽  
Harikishore Pingali ◽  
Vidya Bhushan Lohray ◽  
Walter Wahli ◽  
...  
Keyword(s):  
Ligand Binding ◽  
Molecular Mechanisms ◽  
Resonance Energy Transfer ◽  
Resonance Energy ◽  
Living Cells ◽  
Correlation Spectroscopy ◽  
Peroxisome Proliferator ◽  
Peroxisome Proliferator Activated Receptor ◽  
Peroxisome Proliferator Activated Receptors

The nucleus is an extremely dynamic compartment, and protein mobility represents a key factor in transcriptional regulation. We showed in a previous study that the diffusion of peroxisome proliferator-activated receptors (PPARs), a family of nuclear receptors regulating major cellular and metabolic functions, is modulated by ligand binding. In this study, we combine fluorescence correlation spectroscopy, dual color fluorescence cross-correlation microscopy, and fluorescence resonance energy transfer to dissect the molecular mechanisms controlling PPAR mobility and transcriptional activity in living cells. First, we bring new evidence that in vivo a high percentage of PPARs and retinoid X receptors is associated even in the absence of ligand. Second, we demonstrate that coregulator recruitment (and not DNA binding) plays a crucial role in receptor mobility, suggesting that transcriptional complexes are formed prior to promoter binding. In addition, association with coactivators in the absence of a ligand in living cells, both through the N-terminal AB domain and the AF-2 function of the ligand binding domain, provides a molecular basis to explain PPAR constitutive activity.

Novel control of cAMP-regulated transcription in vascular endothelial cells

2012 ◽  
Vol 40 (1) ◽  
pp. 1-5 ◽  
Author(s):  
Gillian R. Milne ◽  
Timothy M. Palmer ◽  
Stephen J. Yarwood
Keyword(s):  
Endothelial Cells ◽  
Molecular Mechanisms ◽  
Inflammatory Responses ◽  
Vascular Endothelial Cells ◽  
Inflammatory Diseases ◽  
Circulatory System ◽  
Vascular Endothelial ◽  
Protective Mechanisms ◽  
Enhancer Binding Protein ◽  
Developed World

Chronic inflammatory diseases, such as atherosclerosis, are a major cause of death and disability in the developed world. In this respect, although cholesterol obviously plays a predominant role in atherosclerosis, targeting inflammation at lesion sites may be just as important. Indeed, elevated IL-6 (interleukin 6) levels are as strongly associated with coronary heart disease as increased cholesterol. We have been investigating novel cAMP-regulated pathways that combat the action of pro-inflammatory cytokines, such as IL-6 and leptin, in the VECs (vascular endothelial cells) of the circulatory system. In this respect, we have begun to unravel new molecular mechanisms by which the cAMP/Epac1 (exchange protein directly activated by cAMP 1)/Rap1 pathway can initiate a rigorous programme of protective anti-inflammatory responses in VECs. Central to this is the coupling of cAMP elevation to the mobilization of two C/EBP (CCAAT/enhancer-binding protein) family transcription factors, resulting in the induction of the SOCS3 (suppressor of cytokine signalling 3) gene, which attenuates pro-inflammatory cytokine signalling in VECs. These novel ‘protective’ mechanisms of cAMP action will inform the development of the next generation of pharmaceuticals specifically designed to combat endothelial inflammation associated with cardiovascular disease.

Pleiotropic preconditioning-like cardioprotective effects of hypolipidemic drugs in acute ischemia–reperfusion in normal and hypertensive rats

2015 ◽  
Vol 93 (7) ◽  
pp. 495-503 ◽  
Author(s):  
Táňa Ravingerová ◽  
Veronika Ledvényiová-Farkašová ◽  
Miroslav Ferko ◽  
Monika Barteková ◽  
Iveta Bernátová ◽  
...  
Keyword(s):  
Molecular Mechanisms ◽  
Ischemia Reperfusion ◽  
Single Gene ◽  
Cardiac Response ◽  
Acute Ischemia ◽  
Peroxisome Proliferator ◽  
Hypertensive Rats ◽  
Cardioprotective Effects ◽  
Peroxisome Proliferator Activated Receptors ◽  
Hypolipidemic Drugs

Although pleiotropy, which is defined as multiple effects derived from a single gene, was recognized many years ago, and considerable progress has since been achieved in this field, it is not very clear how much this feature of a drug is clinically relevant. During the last decade, beneficial pleiotropic effects from hypolipidemic drugs (as in, effects that are different from the primary ones) have been associated with reduction of cardiovascular risk. As with statins, the agonists of peroxisome proliferator-activated receptors (PPARs), niacin and fibrates, have been suggested to exhibit pleiotropic activity that could significantly modify the outcome of a cardiovascular ailment. This review examines findings demonstrating the impacts of treatment with hypolipidemic drugs on cardiac response to ischemia in a setting of acute ischemia–reperfusion, in relation to PPAR activation. Specifically, it addresses the issue of susceptibility to ischemia, with particular regard to the preconditioning-like cardioprotection conferred by hypolipidemic drugs, as well as the potential molecular mechanisms behind this cardioprotection. Finally, the involvement of PPAR activation in the mechanisms of non-metabolic cardioprotective effects from hypolipidemic drugs, and their effects on normal and pathologically altered myocardium (in the hearts of hypertensive rats) is also discussed.

scholarly journals Peroxisome Proliferator-Activated Receptor Subtype- and Cell-Type-Specific Activation of Genomic Target Genes upon Adenoviral Transgene Delivery

2006 ◽  
Vol 26 (15) ◽  
pp. 5698-5714 ◽  
Author(s):  
Ronni Nielsen ◽  
Lars Grøntved ◽  
Hendrik G. Stunnenberg ◽  
Susanne Mandrup
Keyword(s):  
Target Genes ◽  
Receptor Subtype ◽  
Peroxisome Proliferator ◽  
Cell Type ◽  
Peroxisome Proliferator Activated Receptor ◽  
Molecular Events ◽  
Adenoviral Delivery ◽  
Cell Type Specific ◽  
Peroxisome Proliferator Activated Receptors ◽  
The Individual

ABSTRACT Investigations of the molecular events involved in activation of genomic target genes by peroxisome proliferator-activated receptors (PPARs) have been hampered by the inability to establish a clean on/off state of the receptor in living cells. Here we show that the combination of adenoviral delivery and chromatin immunoprecipitation (ChIP) is ideal for dissecting these mechanisms. Adenoviral delivery of PPARs leads to a rapid and synchronous expression of the PPAR subtypes, establishment of transcriptional active complexes at genomic loci, and immediate activation of even silent target genes. We demonstrate that PPARγ2 possesses considerable ligand-dependent as well as independent transactivation potential and that agonists increase the occupancy of PPARγ2/retinoid X receptor at PPAR response elements. Intriguingly, by direct comparison of the PPARs (α, γ, and β/δ), we show that the subtypes have very different abilities to gain access to target sites and that in general the genomic occupancy correlates with the ability to activate the corresponding target gene. In addition, the specificity and potency of activation by PPAR subtypes are highly dependent on the cell type. Thus, PPAR subtype-specific activation of genomic target genes involves an intricate interplay between the properties of the subtype- and cell-type-specific settings at the individual target loci.

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