Sepsis-induced inhibition of neutrophil chemotaxis is mediated by activation of peroxisome proliferator-activated receptor-γ

AbstractNeutrophils (polymorphonuclear leukocytes [PMNs]) are critical to the immune response, including clearance of infectious pathogens. Sepsis is associated with impaired PMN function, including chemotaxis. PMNs express peroxisome proliferator-activated receptor-γ (PPAR-γ), a ligand-activated nuclear transcription factor involved in immune and inflammatory regulation. The role of PPAR-γ in PMN responses, however, is not well characterized. We report that freshly isolated human PMNs constitutively express PPAR-γ, which is up-regulated by the sepsis-induced cytokines TNF-α and IL-4. PMN chemotactic responses to formylmethionyl-leucyl-phenylalanine (fMLP) and IL-8 were dose-dependently inhibited by treatment with the PPAR-γ ligands troglitazone and 15-deoxy-Δ12,14-prostaglandin J2 (15d-PGJ2) and by transfection of PMN-like HL-60 cells with a constitutively active PPAR-γ construct. Inhibition of chemotaxis by PPAR-γ ligands correlated with decreases in extracellular signal-regulated kinase-1 and -2 activation, actin polymerization, and adherence to a fibrinogen substrate. Furthermore, PMN expression of PPAR-γ was increased in sepsis patients and mice with either of 2 models of sepsis. Finally, treatment with the PPAR-γ antagonist GW9662 significantly reversed the inhibition of PMN chemotaxis and increased peritoneal PMN recruitment in murine sepsis. This study indicates that PPAR-γ activation is involved in PMN chemotactic responses in vitro and may play a role in the migration of these cells in vivo.

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Activation of Peroxisome Proliferator-Activated Receptor γ Does Not Inhibit IL-6 or TNF-α Responses of Macrophages to Lipopolysaccharide In Vitro or In Vivo

The Journal of Immunology ◽

10.4049/jimmunol.164.2.1046 ◽

2000 ◽

Vol 164 (2) ◽

pp. 1046-1054 ◽

Cited By ~ 139

Author(s):

Rolf Thieringer ◽

Judy E. Fenyk-Melody ◽

Cheryl B. Le Grand ◽

Beverly A. Shelton ◽

Patricia A. Detmers ◽

...

Keyword(s):

Peroxisome Proliferator ◽

Peroxisome Proliferator Activated Receptor ◽

Tnf Α

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Piperine Alleviates Doxorubicin-Induced Cardiotoxicity via Activating PPAR-γ in Mice

PPAR Research ◽

10.1155/2019/2601408 ◽

2019 ◽

Vol 2019 ◽

pp. 1-11 ◽

Cited By ~ 2

Author(s):

Jie Yan ◽

Si-Chi Xu ◽

Chun-Yan Kong ◽

Xiao-Yang Zhou ◽

Zhou-Yan Bian ◽

...

Keyword(s):

Oxidative Stress ◽

Cardiac Injury ◽

Inflammatory Factors ◽

Peroxisome Proliferator ◽

Protective Effects ◽

Peroxisome Proliferator Activated Receptor ◽

Ppar Γ ◽

Myocardial Oxidative Stress

Background. Oxidative stress, inflammation and cardiac apoptosis were closely involved in doxorubicin (DOX)-induced cardiac injury. Piperine has been reported to suppress inflammatory response and pyroptosis in macrophages. However, whether piperine could protect the mice against DOX-related cardiac injury remain unclear. This study aimed to investigate whether piperine inhibited DOX-related cardiac injury in mice. Methods. To induce DOX-related acute cardiac injury, mice in DOX group were intraperitoneally injected with a single dose of DOX (15 mg/kg). To investigate the protective effects of piperine, mice were orally treated for 3 weeks with piperine (50 mg/kg, 18:00 every day) beginning two weeks before DOX injection. Results. Piperine treatment significantly alleviated DOX-induced cardiac injury, and improved cardiac function. Piperine also reduced myocardial oxidative stress, inflammation and apoptosis in mice with DOX injection. Piperine also improved cell viability, and reduced oxidative damage and inflammatory factors in cardiomyocytes. We also found that piperine activated peroxisome proliferator-activated receptor-γ (PPAR-γ), and the protective effects of piperine were abolished by the treatment of the PPAR-γ antagonist in vivo and in vitro. Conclusions. Piperine could suppress DOX-related cardiac injury via activation of PPAR-γ in mice.

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The role of Toll-like receptor proteins (TLR) 2 and 4 in mediating inflammation in proximal tubules

AJP Renal Physiology ◽

10.1152/ajprenal.00398.2012 ◽

2013 ◽

Vol 305 (2) ◽

pp. F143-F154 ◽

Cited By ~ 74

Author(s):

Harshini Mudaliar ◽

Carol Pollock ◽

Muralikrishna Gangadharan Komala ◽

Steven Chadban ◽

Huiling Wu ◽

...

Keyword(s):

Diabetic Nephropathy ◽

Inflammatory Responses ◽

Proximal Tubules ◽

Peroxisome Proliferator ◽

Tlr2 Expression ◽

Peroxisome Proliferator Activated Receptor ◽

Ppar Γ ◽

Diagnostic Threshold

Inflammatory responses are central to the pathogenesis of diabetic nephropathy. Toll-like receptors (TLRs) are ligand-activated membrane-bound receptors which induce inflammatory responses predominantly through the activation of NF-κB. TLR2 and 4 are present in proximal tubular cells and are activated by endogenous ligands upregulated in diabetic nephropathy, including high-mobility group box-1 (HMGB1) and fibronectin. Human proximal tubules were exposed to 5 mM (control), 11.2 mM (approximating the clinical diagnostic threshold for diabetes mellitus), and 30 mM (high) glucose for 72 h or 7 days. Cells were harvested for protein, mRNA, and nuclear extract to assess for TLR2, 4, and inflammatory markers. Glucose (11.2 mM) maximally increased TLR2 and 4 expression, HMGB1 release, and NF-κB activation with increased expression of cytokines. However, only TLR2 expression and subsequent NF-κB binding were sustained at 7 days. Recombinant HMGB1 induced NF-κB activation, which was prevented by both TLR2 silencing [small interfering (si)RNA] and TLR4 inhibition. Peroxisome proliferator-activated receptor-γ (PPAR-γ) transcription was reduced by exposure to 11.2 mM glucose with an increase observed at 30 mM glucose at 24 h. This may reflect a compensatory increase in PPAR-γ induced by exposure to 30 mM glucose, limiting the inflammatory response. Therefore, short-term moderate increases in glucose in vitro increase HMGB1, which mediates NF-κB activation through both TLR2 and 4. Furthermore, in vivo, streptozotocin-induced diabetic mice exhibited an increase in tubular TLR2 and HMGB1 expression. These results collectively suggest that TLR2 is likely to be the predominant long-term mediator of NF-κB activation in transducing inflammation in diabetic nephropathy.

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PPARγ Regulates Triclosan Induced Placental Dysfunction

Cells ◽

10.3390/cells11010086 ◽

2021 ◽

Vol 11 (1) ◽

pp. 86

Author(s):

Jing Li ◽

Xiaojie Quan ◽

Yue Zhang ◽

Ting Yu ◽

Saifei Lei ◽

...

Keyword(s):

Cell Viability ◽

Opposite Effect ◽

Peroxisome Proliferator ◽

Peroxisome Proliferator Activated Receptor ◽

Placental Dysfunction ◽

Promising Strategy ◽

Pparγ Agonist ◽

Tnf Α

Exposure to the antibacterial agent triclosan (TCS) is associated with abnormal placenta growth and fetal development during pregnancy. Peroxisome proliferator-activated receptor γ (PPARγ) is crucial in placenta development. However, the mechanism of PPARγ in placenta injury induced by TCS remains unknown. Herein, we demonstrated that PPARγ worked as a protector against TCS-induced toxicity. TCS inhibited cell viability, migration, and angiogenesis dose-dependently in HTR-8/SVneo and JEG-3 cells. Furthermore, TCS downregulated expression of PPARγ and its downstream viability, migration, angiogenesis-related genes HMOX1, ANGPTL4, VEGFA, MMP-2, MMP-9, and upregulated inflammatory genes p65, IL-6, IL-1β, and TNF-α in vitro and in vivo. Further investigation showed that overexpression or activation (rosiglitazone) alleviated cell viability, migration, angiogenesis inhibition, and inflammatory response caused by TCS, while knockdown or inhibition (GW9662) of PPARγ had the opposite effect. Moreover, TCS caused placenta dysfunction characterized by the significant decrease in weight and size of the placenta and fetus, while PPARγ agonist rosiglitazone alleviated this damage in mice. Taken together, our results illustrated that TCS-induced placenta dysfunction, which was mediated by the PPARγ pathway. Our findings reveal that activation of PPARγ might be a promising strategy against the adverse effects of TCS exposure on the placenta and fetus.

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15-keto-prostaglandin E2 activates host peroxisome proliferator-activated receptor gamma (PPAR-γ) to promote Cryptococcus neoformans growth during infection

10.1101/113167 ◽

2017 ◽

Author(s):

Robert J. Evans ◽

Katherine Pline ◽

Catherine A. Loynes ◽

Sarah Needs ◽

Maceler Aldrovandi ◽

...

Keyword(s):

Cryptococcus Neoformans ◽

Immune Surveillance ◽

Fungal Growth ◽

Prostaglandin E ◽

Peroxisome Proliferator ◽

Peroxisome Proliferator Activated Receptor ◽

Ppar Γ ◽

Opportunistic Fungal Pathogen

AbstractCryptococcus neoformans is one of the leading causes of invasive fungal infection in humans worldwide. C. neoformans uses macrophages as a proliferative niche to increase infective burden and avoid immune surveillance. However, the specific mechanisms by which C. neoformans manipulates host immunity to promote its growth during infection remain ill-defined. Here we demonstrate that eicosanoid lipid mediators manipulated and/or produced by C. neoformans play a key role in regulating pathogenesis. C. neoformans is known to secrete several eicosanoids that are highly similar to those found in vertebrate hosts. Using eicosanoid deficient cryptococcal mutants Δplb1 and Δlac1, we demonstrate that prostaglandin E2 is required by C. neoformans for proliferation within macrophages and in vivo during infection. Genetic and pharmacological disruption of host PGE2 synthesis is not required for promotion of cryptococcal growth by eicosanoid production. We find that PGE2 must be dehydrogenated into 15-keto-PGE2 to promote fungal growth, a finding that implicated the host nuclear receptor PPAR-γ. C. neoformans infection of macrophages activates host PPAR-γ and its inhibition is sufficient to abrogate the effect of 15-keto-PGE2 in promoting fungal growth during infection. Thus, we describe the first mechanism of reliance on pathogen-derived eicosanoids in fungal pathogenesis and the specific role of 15-keto-PGE2 and host PPAR-γ in cryptococcosis.Author SummaryCryptococcus neoformans is an opportunistic fungal pathogen that is responsible for significant numbers of deaths in the immunocompromised population worldwide. Here we address whether eicosanoids produced by C. neoformans manipulate host innate immune cells during infection. Cryptococcus neoformans produces several eicosanoids that are notable for their similarity to vertebrate eicosanoids, it is therefore possible that fungal-derived eicosanoids may provoke physiological effects in the host. Using a combination of in vitro and in vivo infection models we identify a specific eicosanoid species - prostaglandin E2 – that is required by C. neoformans for growth during infection. We subsequently show that prostaglandin E2 must be converted to 15-keto-prostaglandin E2 within the host before it has these effects. Furthermore, we find that prostaglandin E2/15-keto-prostaglandin E2 mediated virulence is via activation of host PPAR-γ – an intracellular eicosanoid receptor known to interact with 15-keto-PGE2.

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Repurposing Small Molecules to Target PPAR-γ as New Therapies for Peripheral Nerve Injuries

Biomolecules ◽

10.3390/biom11091301 ◽

2021 ◽

Vol 11 (9) ◽

pp. 1301

Author(s):

Melissa L. D. Rayner ◽

Jess Healy ◽

James B. Phillips

Keyword(s):

Peripheral Nerve ◽

Nerve Regeneration ◽

In Vivo Studies ◽

Peroxisome Proliferator ◽

Neural Cells ◽

Loss Of Function ◽

Peroxisome Proliferator Activated Receptor ◽

Ppar Γ

The slow rate of neuronal regeneration that follows peripheral nerve repair results in poor recovery, particularly where reinnervation of muscles is delayed, leading to atrophy and permanent loss of function. There is a clear clinical need to develop drug treatments that can accelerate nerve regeneration safely, restoring connections before the target tissues deteriorate irreversibly. The identification that the Rho/Rho-associated kinase (ROCK) pathway acts to limit neuronal growth rate is a promising advancement towards the development of drugs. Targeting Rho or ROCK directly can act to suppress the activity of this pathway; however, the pathway can also be modulated through the activation of upstream receptors; one of particular interest being peroxisome proliferator-activated receptor gamma (PPAR-γ). The connection between the PPAR-γ receptor and the Rho/ROCK pathway is the suppression of the conversion of inactive guanosine diphosphate (GDP)-Rho to active guanosine triphosphate GTP-Rho, resulting in the suppression of Rho/ROCK activity. PPAR-γ is known for its role in cellular metabolism that leads to cell growth and differentiation. However, more recently there has been a growing interest in targeting PPAR-γ in peripheral nerve injury (PNI). The localisation and expression of PPAR-γ in neural cells following a PNI has been reported and further in vitro and in vivo studies have shown that delivering PPAR-γ agonists following injury promotes nerve regeneration, leading to improvements in functional recovery. This review explores the potential of repurposing PPAR-γ agonists to treat PNI and their prospective translation to the clinic.

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The Antifibrogenic Potential of PPARγ Ligands in Pulmonary Fibrosis

Journal of Investigative Medicine ◽

10.2310/jim.0b013e31816464e9 ◽

2008 ◽

Vol 56 (2) ◽

pp. 534-538 ◽

Cited By ~ 37

Author(s):

Patricia J. Sime

Keyword(s):

Pulmonary Fibrosis ◽

Mechanism Of Action ◽

Lung Fibroblasts ◽

Peroxisome Proliferator ◽

Peroxisome Proliferator Activated Receptor ◽

Relative Paucity ◽

Ppar Γ ◽

Organ Systems

Pulmonary fibrosis is characterized by the accumulation of fibroblasts, myofibroblasts, collagen, and other extracellular matrix proteins in the interstitium of the lung, with subsequent scarring and destruction of the alveolar capillary interface. In some cases, pulmonary fibrosis is preceded by lung inflammation and can be treated with anti-inflammatory therapies. However, idiopathic pulmonary fibrosis is characterized by a relative paucity of underlying inflammation and currently has no effective treatment. There is increasing evidence that the transcription factor peroxisome proliferator-activated receptor (PPAR) γ plays an important role in controlling cell differentiation and that PPARγ ligands can modify inflammatory and fibrotic responses. Peroxisome proliferator-activated receptor γ ligands, including the thiazolidinedione class of antidiabetic drugs and novel triterpenoid compounds derived from oleanic acid, inhibit TGF-β-stimulated profibrotic differentiation of lung fibroblasts in vitro and reduce lung scarring in animal models of fibrosis. The mechanism of action of the PPARγ ligands is under investigation but seems to involve both PPARγ-dependent and PPARγ-independent pathways. These in vitro and in vivo data highlight the potentially exciting role of PPARγ ligands as novel therapies for fibrosis of the lung and other organ systems prone to scarring. Many of the synthetic PPARγ ligands are orally active, and several are currently available and Food Drug Administration approved for use in therapy of type 2 diabetes. Further research is urgently required to more clearly elucidate the mechanism of action of these drugs and to develop more potent antifibrotic agents for patients with scarring diseases for whom there are currently few effective therapies.

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Retinoid X Receptor Activation During Adipogenesis of Female Mesenchymal Stem Cells Programs a Dysfunctional Adipocyte

Endocrinology ◽

10.1210/en.2018-00056 ◽

2018 ◽

Vol 159 (8) ◽

pp. 2863-2883 ◽

Cited By ~ 15

Author(s):

Bassem M Shoucri ◽

Victor T Hung ◽

Raquel Chamorro-García ◽

Toshi Shioda ◽

Bruce Blumberg

Keyword(s):

Endocrine Disrupting Chemicals ◽

Receptor Activation ◽

Retinoid X Receptor ◽

Peroxisome Proliferator ◽

Peroxisome Proliferator Activated Receptor ◽

Ppar Γ ◽

Obesity And Diabetes ◽

Pparγ Agonist

Abstract Early life exposure to endocrine-disrupting chemicals (EDCs) is an emerging risk factor for the development of obesity and diabetes later in life. We previously showed that prenatal exposure to the EDC tributyltin (TBT) results in increased adiposity in the offspring. These effects linger into adulthood and are propagated through successive generations. TBT activates two nuclear receptors, the peroxisome proliferator–activated receptor (PPAR) γ and its heterodimeric partner retinoid X receptor (RXR), that promote adipogenesis in vivo and in vitro. We recently employed a mesenchymal stem cell (MSC) model to show that TBT promotes adipose lineage commitment by activating RXR, not PPARγ. This led us to consider the functional consequences of PPARγ vs RXR activation in developing adipocytes. We used a transcriptomal approach to characterize genome-wide differences in MSCs differentiated with the PPARγ agonist rosiglitazone (ROSI) or TBT. Pathway analysis suggested functional deficits in TBT-treated cells. We then compared adipocytes differentiated with ROSI, TBT, or a pure RXR agonist IRX4204 (4204). Our data show that RXR activators (“rexinoids,” 4204 and TBT) attenuate glucose uptake, blunt expression of the antidiabetic hormone adiponectin, and fail to downregulate proinflammatory and profibrotic transcripts, as does ROSI. Finally, 4204 and TBT treatment results in an inability to induce markers of adipocyte browning, in part due to sustained interferon signaling. Taken together, these data implicate rexinoids in the development of dysfunctional white adipose tissue that could potentially exacerbate obesity and/or diabetes risk in vivo. These data warrant further screening and characterization of EDCs that activate RXR.

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Inhibition of miR-128-3p Attenuated Doxorubicin-Triggered Acute Cardiac Injury in Mice by the Regulation of PPAR-γ

PPAR Research ◽

10.1155/2021/7595374 ◽

2021 ◽

Vol 2021 ◽

pp. 1-12

Author(s):

Wen-Bin Zhang ◽

Yong-Fa Zheng ◽

Yao-Gui Wu

Keyword(s):

Cardiac Injury ◽

Redox Balance ◽

Peroxisome Proliferator ◽

Protective Effects ◽

Peroxisome Proliferator Activated Receptor ◽

Adeno Associated Virus ◽

Ppar Γ ◽

Myocardial Apoptosis

Background. The clinical usefulness of doxorubicin (DOX), an anthracycline with antitumor activity, is limited by its cardiotoxicity. Oxidative stress and myocardial apoptosis were closely associated with DOX-induced cardiac dysfunction. It has been reported that microRNA-128-3p (miR-128-3p) was involved into the regulation of redox balance. However, the role of miR-128-3p in DOX-related cardiac injury remains not yet understood. The aim of this study was to investigate the biological effect of miR-128-3p in DOX-induced cardiotoxicity. Methods. To induce DOX-related acute cardiac injury, mice were subjected to a single injection of DOX. Inhibition of myocardial miR-128-3p was achieved by an adeno-associated virus (AAV9) system carrying a miR-128-3p sponge. Results. The data in our study indicated that miR-128-3p was upregulated in DOX-treated hearts and cardiomyocytes. Inhibition of miR-128-3p attenuated DOX-related cardiac injury and improved cardiac function in mice. Moreover, miR-128-3p inhibition could suppress myocardial inflammatory response, oxidative damage, and cell apoptotic death in DOX-treated mice. Further analysis showed that miR-128-3p could directly target peroxisome proliferator-activated receptor γ (PPAR-γ) and decrease PPAR-γ expression. Moreover, the protective effects provided by miR-128-3p inhibition were abolished by a PPAR-γ antagonist in vivo and in vitro. Conclusions. miR-128-3p inhibition attenuated DOX-related acute cardiac injury via the regulation of PPAR-γ in mice.

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