Peroxisome proliferator-activated receptor activators inhibit thrombin-induced endothelin-1 production in human vascular endothelial cells by inhibiting the activator protein-1 signaling pathway

Crucial Interactions between Altered Plasma Trace Elements and Fatty Acids Unbalance Ratio to Management of Systemic Arterial Hypertension in Diabetic Patients: Focus on Endothelial Dysfunction

The coexistence of SAH with T2DM is a common comorbidity. In this study, we investigated the link between altered plasma antioxidant trace elements (ATE: manganese, selenium, zinc, and copper) and fatty acids ratio (FAR: polyunsaturated/saturated) imbalance as transition biomarkers between vascular pathology (SAH) to metabolic pathology (T2DM). Our data revealed strong correlation between plasma ATE and FAR profile, which is modified during SAH-T2DM association compared to the healthy group. This relationship is mediated by lipotoxicity (simultaneously prominent visceral adipose tissue lipolysis, significant flow of non-esterified free fatty acids release, TG-Chol-dyslipidemia, high association of total SFA, palmitic acid, arachidonic acid, and PUFA ω6/PUFA ω3; drop in tandem of PUFA/SFA and EPA + DHA); oxidative stress (lipid peroxidation confirmed by TAS depletion and MDA rise, concurrent drop of Zn/Cu-SOD, GPx, GSH, Se, Zn, Se/Mn, Zn/Cu; concomitant enhancement of Cu, Mn, and Fe); endothelial dysfunction (endotheline-1 increase); athero-thrombogenesis risk (concomitant rise of ApoB100/ApoA1, Ox-LDL, tHcy, and Lp(a)), and inflammation (higher of Hs-CRP, fibrinogen and ferritin). Our study opens to new therapeutic targets and to better dietary management, such as to establishing dietary ATE and PUFA ω6/PUFA ω3 or PUFA/SFA reference values for atherosclerotic risk prevention in hypertensive/diabetic patients.

PPARs in atherosclerosis: The spatial and temporal features from mechanism to druggable targets

BACKGROUND

Atherosclerosis is a chronic and complex disease caused by lipid disorder, inflammation, and other factors. It is closely related to cardiovascular diseases, the chief cause of death globally. Peroxisome proliferator-activated receptors (PPARs) are valuable anti-atherosclerosis targets that showcase multiple roles at different pathological stages of atherosclerosis and for cell types at different tissue sites.

AIM OF REVIEW

Considering the spatial and temporal characteristics of the pathological evolution of atherosclerosis, the roles and pharmacological and clinical studies of PPARs were summarized systematically and updated under different pathological stages and in different vascular cells of atherosclerosis. Moreover, selective PPAR modulators and PPAR-pan agonists can exert their synergistic effects meanwhile reducing the side effects, thereby providing novel insight into future drug development for precise spatial-temporal therapeutic strategy of anti-atherosclerosis targeting PPARs.

KEY SCIENTIFIC

Concepts of Review: Based on the spatial and temporal characteristics of atherosclerosis, we have proposed the importance of stage- and cell type-dependent precision therapy. Initially, PPARs improve endothelial cells' dysfunction by inhibiting inflammation and oxidative stress and then regulate macrophages' lipid metabolism and polarization to improve fatty streak. Finally, PPARs reduce fibrous cap formation by suppressing the proliferation and migration of vascular smooth muscle cells (VSMCs). Therefore, research on the cell type-specific mechanisms of PPARs can provide the foundation for space-time drug treatment. Moreover, pharmacological studies have demonstrated that several drugs or compounds can exert their effects by the activation of PPARs. Selective PPAR modulators (that specifically activate gene subsets of PPARs) can exert tissue and cell-specific effects. Furthermore, the dual- or pan-PPAR agonist could perform a better role in balancing efficacy and side effects. Therefore, research on cells/tissue-specific activation of PPARs and PPAR-pan agonists can provide the basis for precision therapy and drug development of PPARs.

An insight to treat cardiovascular diseases through phytochemicals targeting PPAR-α

Peroxisome proliferator-activated receptor-α (PPAR-α) belonging to the nuclear hormone receptor superfamily is a promising target for CVDs which mechanistically improves the production of high-density lipid as well as inhibit vascular smooth muscle cell proliferation. PPAR-α mainly interferes with adenosine monophosphate-activated protein kinase, transforming growth factor-β-activated kinase, and nuclear factor-κB pathways to protect against cardiac complications. Natural products/extracts could serve as a potential therapeutic strategy in CVDs for targeting PPAR-α with broad safety margins. In recent years, the understanding of naturally derived PPAR-α agonists has considerably improved; however, the information is scattered. In vitro and in vivo studies on acacetin, apigenin, arjunolic acid, astaxanthin, berberine, resveratrol, vaticanol C, hispidulin, ginsenoside Rb3, and genistein showed significant effects in CVDs complications by targeting PPAR-α. With the aim of demonstrating the tremendous chemical variety of natural products targeting PPAR-α in CVDs, this review provides insight into various natural products that can work to prevent CVDs by targeting the PPAR-α receptor along with their detailed mechanism.

Functional role of Ash2l in oxLDL induced endothelial dysfunction and atherosclerosis

Endothelial injury and dysfunction in the artery wall fuel the process of atherosclerosis. As a key epigenetic regulator, Ash2l (Absent, small, or homeotic-Like 2) is involved in regulating vascular injury and its complications. However, the role of Ash2l in atherosclerosis has not yet been fully elucidated. Here, we found increased Ash2l expression in high-cholesterol diet-fed ApoE-/- mice and oxidized LDL (oxLDL) treated endothelial cells (ECs). Furthermore, Ash2l promoted the scavenger receptors transcription by catalyzing histone H3 lysine 4 (H3K4) trimethylation at the promoter region of transcription factor peroxisome proliferator-activated receptor-γ (PPARγ) and triggered the activation of the pro-inflammatory nuclear factor-kappa B (NF-κB) by enhancing interaction between CD36 and toll-like receptor 4 (TLR4). Meanwhile, enhanced expression of scavenger receptors drove more oxLDL uptake by ECs. In vivo studies revealed that ECs-specific Ash2l knockdown reduced atherosclerotic lesion formation and promoted fibrous cap stability in the aorta of ApoE-/- mice, which was partly associated with a reduced endothelial activation by suppressing scavenger receptors and the uptake of lipids by ECs. Collectively, our findings identify Ash2l as a novel regulator that mediates endothelial injury and atherosclerosis. Targeting Ash2l may provide valuable insights for developing novel therapeutic candidates for atherosclerosis.

Adipose tissue inflammation linked to obesity: A review of current understanding, therapies and relevance of phyto-therapeutics

Obesity is a current global challenge affecting all ages and is characterized by the up-regulated secretion of bioactive factors/pathways which result in adipose tissue inflammation (ATI). Current obesity therapies are mainly focused on lifestyle (diet/nutrition) changes. This is because many chemosynthetic anti-obesogenic medications cause adverse effects like diarrhoea, dyspepsia, and faecal incontinence, among others. As such, it is necessary to appraise the efficacies and mechanisms of action of safer, natural alternatives like plant-sourced compounds, extracts [extractable phenol (EP) and macromolecular antioxidant (MA) extracts], and anti-inflammatory peptides, among others, with a view to providing a unique approach to obesity care. These natural alternatives may constitute potent therapies for ATI linked to obesity. The potential of MA compounds (analysed for the first time in this review) and extracts in ATI and obesity management is elucidated upon, while also highlighting research gaps and future prospects. Furthermore, immune cells, signalling pathways, genes, and adipocyte cytokines play key roles in ATI responses and are targeted in certain therapies. As a result, this review gives an in-depth appraisal of ATI linked to obesity, its causes, mechanisms, and effects of past, present, and future therapies for reversal and alleviation of ATI. Achieving a significant decrease in morbidity and mortality rates attributed to ATI linked to obesity and related comorbidities is possible as research improves our understanding over time.

Osteoarthritis: Role of Peroxisome Proliferator-Activated Receptors

Osteoarthritis (OA) represents the foremost degenerative joint disease observed in a clinical context. The escalating issue of population aging significantly exacerbates the prevalence of OA, thereby imposing an immense annual economic burden on societies worldwide. The current therapeutic landscape falls short in offering reliable pharmaceutical interventions and efficient treatment methodologies to tackle this growing problem. However, the scientific community continues to dedicate significant efforts towards advancing OA treatment research. Contemporary studies have discovered that the progression of OA may be slowed through the strategic influence on peroxisome proliferator-activated receptors (PPARs). PPARs are ligand-activated receptors within the nuclear hormone receptor family. The three distinctive subtypes-PPARα, PPARβ/δ, and PPARγ-find expression across a broad range of cellular terminals, thus managing a multitude of intracellular metabolic operations. The activation of PPARγ and PPARα has been shown to efficaciously modulate the NF-κB signaling pathway, AP-1, and other oxidative stress-responsive signaling conduits, leading to the inhibition of inflammatory responses. Furthermore, the activation of PPARγ and PPARα may confer protection to chondrocytes by exerting control over its autophagic behavior. In summation, both PPARγ and PPARα have emerged as promising potential targets for the development of effective OA treatments.

The Role of Peroxisome Proliferator-Activated Receptors in Preeclampsia

Preeclampsia is a common pregnancy-related hypertensive disorder. Often presenting as preexisting or new-onset hypertension complicated by proteinuria and/or end-organ dysfunction, preeclampsia significantly correlates with maternal and perinatal morbidity and mortality. Peroxisome proliferator-activated receptors (PPARs) are nuclear receptor proteins that regulate gene expression. In order to investigate the role of PPARs in the pathophysiology of preeclampsia, we conducted a literature review using the MEDLINE and LIVIVO databases. The search terms "peroxisome proliferator-activated receptor", "PPAR", and "preeclampsia" were employed and we were able to identify 35 relevant studies published between 2002 and 2022. Different study groups reached contradictory conclusions in terms of PPAR expression in preeclamptic placentae. Interestingly, PPARγ agonists alone, or in combination with well-established pharmaceutical agents, were determined to represent novel, potent anti-preeclamptic treatment alternatives. In conclusion, PPARs seem to play a significant role in preeclampsia.

Peroxisome Proliferator-Activated Receptor-Targeted Therapies: Challenges upon Infectious Diseases

Peroxisome proliferator-activated receptors (PPARs) α, β, and γ are nuclear receptors that orchestrate the transcriptional regulation of genes involved in a variety of biological responses, such as energy metabolism and homeostasis, regulation of inflammation, cellular development, and differentiation. The many roles played by the PPAR signaling pathways indicate that PPARs may be useful targets for various human diseases, including metabolic and inflammatory conditions and tumors. Accumulating evidence suggests that each PPAR plays prominent but different roles in viral, bacterial, and parasitic infectious disease development. In this review, we discuss recent PPAR research works that are focused on how PPARs control various infections and immune responses. In addition, we describe the current and potential therapeutic uses of PPAR agonists/antagonists in the context of infectious diseases. A more comprehensive understanding of the roles played by PPARs in terms of host-pathogen interactions will yield potential adjunctive personalized therapies employing PPAR-modulating agents.

The Potential for Placental Activation of PPARγ to Improve the Angiogenic Profile in Preeclampsia

Preeclampsia (PE) is one of the most common causes of maternal-fetal morbidity and mortality world-wide. While the underlying causes of PE remain elusive, aberrant trophoblast differentiation and function are thought to cause an imbalance of secreted angiogenic proteins resulting in systemic endothelial dysfunction and organ damage in the mother. The placental dysfunction is also characterized by a reduction of the transcription factor, peroxisome proliferator activated receptor γ (PPARγ) which normally promotes trophoblast differentiation and healthy placental function. This study aimed to understand how placental activation of PPARγ effects the secretion of angiogenic proteins and subsequently endothelial function. To study this, healthy and PE placental tissues were cultured with or without the PPARγ agonist, Rosiglitazone, and a Luminex assay was performed to measure secreted proteins from the placenta. To assess the angiogenic effects of placental activation of PPARγ, human umbilical vein endothelial cells (HUVECs) were cultured with the placental conditioned media and the net angiogenic potential of these cells was measured by a tube formation assay. This is the first study to show PPARγ's beneficial effect on the angiogenic profile in the human preeclamptic placenta through the reduction of anti-angiogenic angiopoietin-2 and soluble endoglin and the upregulation of pro-angiogenic placental growth factor, fibroblast growth factor-2, heparin-binding epidermal growth factor, and follistatin. The changes in the angiogenic profile were supported by the increased angiogenic potential observed in the HUVECs when cultured with conditioned media from rosiglitazone-treated preeclamptic placentas. The restoration of these disrupted pathways by activation of PPARγ in the preeclamptic placenta offers potential to improve placental and endothelial function in PE.

The Key Molecular Mechanisms of Sini Decoction Plus Ginseng Soup to Rescue Acute Liver Failure: Regulating PPARα to Reduce Hepatocyte Necroptosis?

Purpose

This study aimed to investigate the improvement effect of Sini Decoction plus Ginseng Soup (SNRS) on the LPS/D-GalN-induced acute liver failure (ALF) mouse model and the molecular mechanism of the SNRS effect.

Methods

To study the protective effect of SNRS on ALF mice, the ICR mice were firstly divided into 4 groups: Control group (vehicle-treated), Model group (LPS/D-GalN), SNRS group (LPS/D-GalN+SNRS), and Silymarin group (LPS/D-GalN+Silymarin), the therapeutic drug was administered by gavage 48h, 24h before, and 10 min after LPS/D-GalN injection. On this basis, the peroxisome proliferator-activated receptor (PPAR) α agonist (WY14643) and inhibitor (GW6471) were added to verify whether the therapeutic mechanism of SNRS is related to its promoting effect on PPARα. The animals are grouped as follows: Control group (vehicle-treated), Model group (LPS/D-GalN+DMSO), SNRS group (LPS/D-GalN+SNRS+DMSO), Inhibitor group (LPS/D-GalN+GW6471), Agonist group (LPS/D-GalN+WY14643), and Inhibitor+SNRS group (LPS/D-GalN+GW6471+SNRS).

Results

The protective effect of SNRS on the ALF model is mainly reflected in the reduction of serum alanine aminotransaminase (ALT) and aspartate aminotransaminase (AST) as well as the ameliorated pathology of the liver tissue. The survival rate of ALF mice treated with SNRS was significantly increased. Further mechanism studies showed that SNRS significantly promoted the protein expression of PPARα and decreased the expression of necroptosis proteins (RIP3, MLKL, p-MLKL) in ALF mice. Reduced necroptosis resulted in decreased HMGB1 release, which in turn inhibited the activation of TLR4-JNK and NLRP3 inflammasome signaling pathways and the expression of NF-κB protein induced by LPS/D-GalN. The expression of CPT1A, a key enzyme involved in fatty acid β-oxidation, was found to be significantly up-regulated in the SNRS treated group, accompanied by an increased adenosine-triphosphate (ATP) level, which may be the relevant mechanism by which SNRS reduces necroptosis.

Conclusion

The potential therapeutic effect of SNRS on ALF may be through promoting the expression of PPARα and increasing the level of ATP in liver tissue, thereby inhibiting necroptosis of hepatocytes, reducing hepatocyte damage, and improving liver function.

Human Milk Lipids Induce Important Metabolic and Epigenetic Changes in Neonates

Lipids are a major source of energy during the fetal/neonatal period. Most are received from the mother, transplacentally during the intrauterine period or via maternal milk after birth. However, in addition to the known nutritional roles, lipids are now known to bind a variety of cellular receptors to regulate specific patterns in metabolism and gene expression. The expression of these receptors is regulated by various genetic and environmental stimuli, and ligation can activate positive-feedback loops in the expression and the activity of downstream signaling pathways. The authors summarize the role of lipid ligands, cognate receptors, epigenetic regulation, and downstream signaling.

Molecular Biological and Clinical Understanding of the Statin Residual Cardiovascular Disease Risk and Peroxisome Proliferator-Activated Receptor Alpha Agonists and Ezetimibe for Its Treatment

Several randomized, double blind, placebo-controlled trials (RCTs) have demonstrated that low-density lipoprotein cholesterol (LDL-C) lowering by using statins, including high-doses of strong statins, reduced the development of cardiovascular disease (CVD). However, among the eight RCTs which investigated the effect of statins vs. placebos on the development of CVD, 56-79% of patients had the residual CVD risk after the trials. In three RCTs which investigated the effect of a high dose vs. a usual dose of statins on the development of CVD, 78-87% of patients in the high-dose statin arms still had the CVD residual risk after the trials. An analysis of the characteristics of patients in the RCTs suggests that elevated triglyceride (TG) and reduced high-density lipoprotein cholesterol (HDL-C), the existence of obesity/insulin resistance, and diabetes may be important metabolic factors which determine the statin residual CVD risk. To understand the association between lipid abnormalities and the development of atherosclerosis, we show the profile of lipoproteins and their normal metabolism, and the molecular and biological mechanisms for the development of atherosclerosis by high TG and/or low HDL-C in insulin resistance. The molecular biological mechanisms for the statin residual CVD risk include an increase of atherogenic lipoproteins such as small dense LDL and remnants, vascular injury and remodeling by inflammatory cytokines, and disturbed reverse cholesterol transport. Peroxisome proliferator-activated receptor alpha (PPARα) agonists improve atherogenic lipoproteins, reverse the cholesterol transport system, and also have vascular protective effects, such as an anti-inflammatory effect and the reduction of the oxidative state. Ezetimibe, an inhibitor of intestinal cholesterol absorption, also improves TG and HDL-C, and reduces intestinal cholesterol absorption and serum plant sterols, which are increased by statins and are atherogenic, possibly contributing to reduce the statin residual CVD risk.

The pleiotropic peroxisome proliferator activated receptors: Regulation and therapeutics

The Peroxisome proliferator-activated receptors (PPARs) are key regulators of metabolic events in our body. Owing to their implication in maintenance of homeostasis, both PPAR agonists and antagonists assume therapeutic significance. Understanding the molecular mechanisms of each of the PPAR isotypes in the healthy body and during disease is crucial to exploiting their full therapeutic potential. This article is an attempt to present a rational analysis of the multifaceted therapeutic effects and underlying mechanisms of isotype-specific PPAR agonists, dual PPAR agonists, pan PPAR agonists as well as PPAR antagonists. A holistic understanding of the mechanistic dimensions of these key metabolic regulators will guide future efforts to identify novel molecules in the realm of metabolic, inflammatory and immunotherapeutic diseases.

A GSK3-SRF Axis Mediates Angiotensin II Induced Endothelin Transcription in Vascular Endothelial Cells

Endothelin, encoded by ET1, is a vasoactive substance primarily synthesized in vascular endothelial cells (VECs). Elevation of endothelin levels, due to transcriptional hyperactivation, has been observed in a host of cardiovascular diseases. We have previously shown that serum response factor (SRF) is a regulator of ET1 transcription in VECs. Here we report that angiotensin II (Ang II) induced ET1 transcription paralleled activation of glycogen synthase kinase 3 (GSK3) in cultured VECs. GSK3 knockdown or pharmaceutical inhibition attenuated Ang II induced endothelin expression. Of interest, the effect of GSK3 on endothelin transcription relied on the conserved SRF motif within the ET1 promoter. Further analysis revealed that GSK3 interacted with and phosphorylated SRF at serine 224. Phosphorylation of SRF by GSK3 did not influence its recruitment to the ET1 promoter. Instead, GSK3-mediated SRF phosphorylation potentiated its interaction with MRTF-A, a key co-factor for SRF, which helped recruit the chromatin remodeling protein BRG1 to the ET1 promoter resulting in augmented histone H3 acetylation/H3K4 trimethylation. Consistently, over-expression of a constitutively active GSK enhanced Ang II-induced ET1 transcription and knockdown of either MRTF-A or BRG1 abrogated the enhancement of ET1 transcription. In conclusion, our data highlight a previously unrecognized mechanism that contributes to the transcriptional regulation of endothelin. Targeting this GSK3-SRF axis may yield novel approaches in the intervention of cardiovascular diseases.

Exosomes from Long Noncoding RNA-Gm37494-ADSCs Repair Spinal Cord Injury via Shifting Microglial M1/M2 Polarization

Spinal cord injury (SCI) may lead to severe motor and sensory dysfunction, causing high mortality and disability rates. Adipose tissue-derived mesenchymal stem/stromal cells (ADSCs), especially hypoxia-pretreated ADSCs, represent an effective therapy for SCI by promoting the secretion of exosomes (Exos). Here, we investigated the therapeutic efficacy of exosomes secreted by ADSCs under hypoxia (HExos) and explored potential target molecules. We utilized nanoparticle tracking analysis, electron microscopy, qRT-PCR, and western blotting to analyze differences between HExos and Exos groups. The expression of long noncoding RNAs (lncRNAs) was examined by high-throughput sequencing. The therapeutic effects of different Exos treatments were compared in vitro and in an SCI model in vivo. The interaction between lncRNAs, microRNAs, and mRNA was examined by luciferase reporter experiments. We employed enzyme-linked immunosorbent assay and immunofluorescence to measure inflammatory factor expression and microglial polarization. The results showed that HExos was more effective than Exos for repairing SCI by suppressing inflammatory factor expression, promoting functional recovery, and shifting microglia from M1 to M2 polarization. High-throughput sequencing showed that LncGm37494 expression was significantly higher in HExos than Exos, and its upregulation promoted microglial M1/M2 polarization by inhibiting miR-130b-3p and promoting PPARγ expression, as shown by luciferase reporter experiments. Exos from lncGm37494 overexpressing ADSCs showed a similar therapeutic effect than HExos. The results indicated that HExos repair SCI by delivering lncGm37494, advising that lncGm3749 functions importantly in microenvironmental regulation and shows possibility for SCI treatments.

Transcriptional Regulation of Thrombin-Induced Endothelial VEGF Induction and Proangiogenic Response

Thrombin, the ligand of the protease-activated receptor 1 (PAR1), is a well-known stimulator of proangiogenic responses in vascular endothelial cells (ECs), which are mediated through the induction of vascular endothelial growth factor (VEGF). However, the transcriptional events underlying this thrombin-induced VEGF induction and angiogenic response are less well understood at present. As reported here, we conducted detailed promotor activation and signal transduction pathway studies in human microvascular ECs, to decipher the transcription factors and the intracellular signaling events underlying the thrombin and PAR-1-induced endothelial VEGF induction. We found that c-FOS is a key transcription factor controlling thrombin-induced EC VEGF synthesis and angiogenesis. Upon the binding and internalization of its G-protein-coupled PAR-1 receptor, thrombin triggers ERK1/2 signaling and activation of the nuclear AP-1/c-FOS transcription factor complex, which then leads to VEGF transcription, extracellular secretion, and concomitant proangiogenic responses of ECs. In conclusion, exposure of human microvascular ECs to thrombin triggers signaling through the PAR-1–ERK1/2–AP-1/c-FOS axis to control VEGF gene transcription and VEGF-induced angiogenesis. These observations offer a greater understanding of endothelial responses to thromboinflammation, which may help to interpret the results of clinical trials tackling the conditions associated with endothelial injury and thrombosis.

Role of the Peroxisome Proliferator Activated Receptors in Hypertension

Nuclear receptors represent a large family of ligand-activated transcription factors which sense the physiological environment and make long-term adaptations by mediating changes in gene expression. In this review, we will first discuss the fundamental mechanisms by which nuclear receptors mediate their transcriptional responses. We will focus on the PPAR (peroxisome proliferator-activated receptor) family of adopted orphan receptors paying special attention to PPARγ, the isoform with the most compelling evidence as an important regulator of arterial blood pressure. We will review genetic data showing that rare mutations in PPARγ cause severe hypertension and clinical trial data which show that PPARγ activators have beneficial effects on blood pressure. We will detail the tissue- and cell-specific molecular mechanisms by which PPARs in the brain, kidney, vasculature, and immune system modulate blood pressure and related phenotypes, such as endothelial function. Finally, we will discuss the role of placental PPARs in preeclampsia, a life threatening form of hypertension during pregnancy. We will close with a viewpoint on future research directions and implications for developing novel therapies.

LMWF5A suppresses cytokine release by modulating select inflammatory transcription factor activity in stimulated PBMC

Background

Dysregulation of transcription and cytokine expression has been implicated in the pathogenesis of a variety inflammatory diseases. The resulting imbalance between inflammatory and resolving transcriptional programs can cause an overabundance of pro-inflammatory, classically activated macrophage type 1 (M1) and/or helper T cell type 1 (Th1) products, such as IFNγ, TNFα, IL1-β, and IL12, that prevent immune switching to resolution and healing. The low molecular weight fraction of human serum albumin (LMWF5A) is a novel biologic drug that is currently under clinical investigation for the treatment of osteoarthritis and the hyper-inflammatory response associated with COVID-19. This study aims to elucidate transcriptional mechanisms of action involved with the ability of LMWF5A to reduce pro-inflammatory cytokine release.

Methods

ELISA arrays were used to identify cytokines and chemokines influenced by LMWF5A treatment of LPS-stimulated peripheral blood mononuclear cells (PBMC). The resulting profiles were analyzed by gene enrichment to gain mechanistic insight into the biologic processes and transcription factors (TFs) underlying the identified differentially expressed cytokines. DNA-binding ELISAs, luciferase reporter assays, and TNFα or IL-1β relative potency were then employed to confirm the involvement of enriched pathways and TFs.

Results

LMWF5A was found to significantly inhibit a distinct set of pro-inflammatory cytokines (TNFα, IL-1β, IL-12, CXCL9, CXCL10, and CXCL11) associated with pro-inflammatory M1/Th1 immune profiles. Gene enrichment analysis also suggests these cytokines are, in part, regulated by NF-κB and STAT transcription factors. Data from DNA-binding and reporter assays support this with LMWF5A inhibition of STAT1α DNA-binding activity as well as a reduction in overall NF-κB-driven luciferase expression. Experiments using antagonists specific for the immunomodulatory and NF-κB/STAT-repressing transcription factors, peroxisome proliferator-activated receptor (PPAR)γ and aryl hydrocarbon receptor (AhR), indicate these pathways are involved in the LMWF5A mechanisms of action by reducing LMWF5A drug potency as measured by TNFα and IL-1β release.

Conclusion

In this report, we provide evidence that LMWF5A reduces pro-inflammatory cytokine release by activating the immunoregulatory transcription factors PPARγ and AhR. In addition, our data indicate that LMWF5A suppresses NF-κB and STAT1α pro-inflammatory pathways. This suggests that LMWF5A acts through these mechanisms to decrease pro-inflammatory transcription factor activity and subsequent inflammatory cytokine production.

Neurovascular protection by peroxisome proliferator-activated receptor α in ischemic stroke

Ischemic stroke is a leading cause of death and disability worldwide. Currently, the only pharmacological therapy for ischemic stroke is thrombolysis with tissue plasminogen activator that has a narrow therapeutic window and increases the risk of intracerebral hemorrhage. New pharmacological treatments for ischemic stroke are desperately needed, but no neuroprotective drugs have successfully made it through clinical trials. Beneficial effects of peroxisome proliferator-activated receptor alpha (PPARα) activation on vascular integrity and function have been reported, and PPARα agonists have clinically been used for many years to manage cardiovascular disease. Thus, PPARα has gained interest in recent years as a target for neurovascular disease such as ischemic stroke. Accumulating preclinical evidence suggests that PPARα activation modulates several pathophysiological hallmarks of stroke such as oxidative stress, blood-brain barrier (BBB) dysfunction, and neuroinflammation to improve functional recovery. Therefore, this review summarizes the various actions PPARα exerts in neurovascular health and disease and the potential of employing exogenous PPARα agonists for future pharmacological treatment of ischemic stroke.

Peroxisome proliferator-activated receptor gamma blunts endothelin-1-mediated contraction of the uterine artery in a murine model of high-altitude pregnancy

The environmental hypoxia of high altitude (HA) increases the incidence of intrauterine growth restriction (IUGR) approximately threefold. The peroxisome proliferator-activated receptor γ (PPAR-γ), a ligand-activated nuclear receptor that promotes vasorelaxation by increasing nitric oxide and downregulating endothelin-1 (ET-1) production, has been implicated in IUGR. Based on our prior work indicating that pharmacologic activation of the PPARγ pathway protects against hypoxia-associated IUGR, we used an experimental murine model to determine whether such effects may be attributed to vasodilatory effects in the uteroplacental circulation. Using wire myography, ex vivo vasoreactivity studies were conducted in uterine arteries (UtA) isolated from pregnant mice exposed to hypoxia or normoxia from gestational day 14.5 to 18.5. Exposure to troglitazone, a high-affinity PPARγ agonist-induced vasorelaxation in UtA preconstricted with phenylephrine, with HA-UtA showing increased sensitivity. Troglitazone blunted ET-1-induced contraction of UtA in hypoxic and normoxic dams equivalently. Immunohistological analysis revealed enhanced staining for ET-1 receptors in the placental labyrinthine zone in hypoxic compared to normoxic dams. Our results suggest that pharmacologic PPAR-γ activation, via its vasoactive properties, may protect the fetal growth under hypoxic conditions by improving uteroplacental perfusion and thereby justify further investigation into PPARγ as a therapeutic target for IUGR in pregnancies complicated by hypoxia.

Peroxisome Proliferator-Activated Receptor γ Agonist Rosiglitazone Protects Blood-Brain Barrier Integrity Following Diffuse Axonal Injury by Decreasing the Levels of Inflammatory Mediators Through a Caveolin-1-Dependent Pathway

Our early experiments confirmed that rosiglitazone (RSG), a peroxisome proliferator-activated receptor γ (PPARγ) agonist, had therapeutic potential for the treatment of diffuse axonal injury (DAI) by inhibiting the expression of amyloid-beta precursor protein and reducing the loss and abnormal phosphorylation of tau, but the underlying mechanisms were not fully defined. In this study, we aimed to investigate a possible role for PPARγ in the protection of blood-brain barrier (BBB) integrity in a rat model of DAI, and the underlying mechanisms. PPAR agonists and antagonists were intraperitoneally injected after DAI. Treatment with RSG ameliorated axonal injury, cell apoptosis, glia activation, and the release of inflammatory factors such as TNF-α, IL-1β, and IL-6. It also increased the expression of tight junction-associated proteins like ZO-1, claudin-5, and occludin-1, whereas the PPARγ antagonist GW9662 had the opposite effects. These effects were also studied in a BBB in vitro model, consisting of a monolayer of human microvascular endothelial cells (HBMECs) subjected to oxygen and glucose deprivation (OGD). Treatment with RSG ameliorated the loss of BBB integrity and the increased permeability induced by OGD by reducing the release of inflammatory factors and maintaining the expression of tight junction-associated proteins. Interestingly, caveolin-1 was found located mainly in endothelial cells, and RSG increased the expression of caveolin-1, which decreased following OGD. In contrast, caveolin-1 siRNA abrogated the protective effects of RSG in the in vitro BBB model. In conclusion, we provide evidence that PPARγ plays an important role in a series of processes associated with DAI, and that the PPARγ agonist RSG can protect BBB integrity by decreasing the levels of inflammatory mediators through a caveolin-1-dependent pathway.

Pioglitazone Modulates the Vascular Contractility in Hypertension by Interference with ET-1 Pathway

Endothelin-1 (ET-1) is an important modulator of the vascular tone and a proinflammatory molecule that contributes to the vascular damage observed in hypertension. Peroxisome-proliferator activated receptors-γ (PPARγ) agonists show cardioprotective properties by decreasing inflammatory molecules such as COX-2 and reactive oxygen species (ROS), among others. We investigated the possible modulatory effect of PPARγ activation on the vascular effects of ET-1 in hypertension. In spontaneously hypertensive rats (SHR), but not in normotensive rats, ET-1 enhanced phenylephrine-induced contraction through ET_A by a mechanism dependent on activation of TP receptors by COX-2-derived prostacyclin and reduction in NO bioavailability due to enhanced ROS production. In SHR, the PPARγ agonist pioglitazone (2.5 mg/Kg·day, 28 days) reduced the increased ET_A levels and increased those of ET_B. After pioglitazone treatment of SHR, ET-1 through ET_B decreased ROS levels that resulted in increased NO bioavailability and diminished phenylephrine contraction. In vascular smooth muscle cells from SHR, ET-1 increased ROS production through AP-1 and NFκB activation, leading to enhanced COX-2 expression. These effects were blocked by pioglitazone. In summary, in hypertension, pioglitazone shifts the vascular ET_A/ET_B ratio, reduces ROS/COX-2 activation and increases NO availability; these changes explain the effect of ET-1 decreasing phenylephrine-induced contraction.

Pharmacological activation of peroxisome proliferator-activated receptor γ (PPAR-γ) protects against hypoxia-associated fetal growth restriction

The hypoxia of high-altitude (HA) residence increases the risk of intrauterine growth restriction (IUGR) and preeclampsia 3-fold, augmenting perinatal morbidity and mortality and the risk for childhood and adult disease. Currently, no effective therapies exist to prevent these vascular disorders of pregnancy. The peroxisome proliferator-activated receptor γ (PPAR-γ) is an important regulator of uteroplacental vascular development and function and has been implicated in the pathogenesis of IUGR and preeclampsia. Here, we used a model of HA pregnancy in mice to determine whether hypoxia-induced fetal growth restriction reduces placental PPAR-γ protein expression and placental vascularization and, if so, to evaluate the effectiveness of the selective PPAR-γ agonist pioglitazone (PIO) for preventing hypoxia-induced IUGR. Hypoxia resulted in asymmetric IUGR, placental insufficiency, and reduced placental PPAR-γ expression; PIO prevented approximately half of the fetal growth restriction and attenuated placental insufficiency. PIO did not affect fetal growth under normoxia. Although PIO was beneficial for fetal growth, PIO treatment reduced placental vascular density of the labrynthine zone in normoxic and hypoxic (Hx) conditions, and mean vascular area was reduced in the Hx group. Our results suggest that pharmacological PPAR-γ activation is a potential strategy for preventing IUGR in pregnancies complicated by hypoxia, although further studies are needed to identify its likely metabolic or vascular mechanisms.-Lane, S. L., Dodson, R. B., Doyle, A. S., Park, H., Rathi, H., Matarrazo, C. J., Moore, L. G., Lorca, R. A., Wolfson, G. H., Julian, C. G. Pharmacological activation of peroxisome proliferator-activated receptor γ (PPAR-γ) protects against hypoxia-associated fetal growth restriction.

Evidence that peroxisome proliferator-activated receptor γ suppresses squamous carcinogenesis through anti-inflammatory signaling and regulation of the immune response

A variety of evidence suggests that peroxisome proliferator-activated receptor (PPAR)γ agonists may represent a potential pharmacologic target in the prevention or treatment of skin cancer. In particular, recent reports suggest that PPARγ activation may exert at least some of its anti-neoplastic effects through the suppression of tumor promoting chronic inflammation as well as by strengthening antitumor immune responses. This activity is thought to occur through a distinct mode of ligand interaction with PPARγ that causes transrepression of transcription factors that are involved in inflammatory and immunomodulatory signaling. However, current thiazolidinedione (TZD)-type PPARγ agonists have significant safety concerns that limit their usefulness as a preventive or therapeutic option. Due to the relatively large ligand binding pocket of PPARγ, a diverse group of ligands can be seen to interact with distinct modes of binding to PPARγ, leading to the phenomenon of partial agonist activity and selective PPARγ modulators (SPPARγM). This has led to the development of ligands that are tailored to deliver desired pharmacologic activity, but lack some of the negative side effects associated with full agonists, such as the currently utilized TZD-type PPARγ agonists. In addition, there is evidence that a number of phytochemicals that are currently being touted as antineoplastic nutraceuticals also possess PPARγ activity that may partially explain their pharmacologic activity. We propose that one or more of these partial agonists, SPPARγMs, or putative phytochemical PPARγ ligands could presumably be used as a starting point to design more efficacious anti-neoplastic PPARγ ligands that lack adverse pharmacological effects.

C/VDdb: A multi-omics expression profiling database for a knowledge-driven approach in cardiovascular disease (CVD)

The cardiovascular disease (C/VD) database is an integrated and clustered information resource that covers multi-omic studies (microRNA, genomics, proteomics and metabolomics) of cardiovascular-related traits with special emphasis on coronary artery disease (CAD). This resource was built by mining existing literature and public databases and thereafter manual biocuration was performed. To enable integration of omic data from distinct platforms and species, a specific ontology was applied to tie together and harmonise multi-level omic studies based on gene and protein clusters (CluSO) and mapping of orthologous genes (OMAP) across species. CAD continues to be a leading cause of death in the population worldwide, and it is generally thought to be an age-related disease. However, CAD incidence rates are now known to be highly influenced by environmental factors and interactions, in addition to genetic determinants. With the complexity of CAD aetiology, there is a difficulty in research studies to elucidate general elements compared to other cardiovascular diseases. Data from 92 studies, covering 13945 molecular entries (4353 unique molecules) is described, including data descriptors for experimental setup, study design, discovery-validation sample size and associated fold-changes of the differentially expressed molecular features (p-value<0.05). A dedicated interactive web interface, equipped with a multi-parametric search engine, data export and indexing menus are provided for a user-accessible browsing experience. The main aim of this work was the development of a data repository linking clinical information and molecular differential expression in several CVD-related traits from multi-omics studies (genomics, transcriptomics, proteomics and metabolomics). As an example case of how to query and identify data sets within the database framework and concomitantly demonstrate the database utility, we queried CAD-associated studies and performed a systems-level integrative analysis. URL: www.padb.org/cvd

Molecular Actions of PPARα in Lipid Metabolism and Inflammation

Peroxisome proliferator-activated receptor α (PPARα) is a nuclear receptor of clinical interest as a drug target in various metabolic disorders. PPARα also exhibits marked anti-inflammatory capacities. The first-generation PPARα agonists, the fibrates, have however been hampered by drug-drug interaction issues, statin drop-in, and ill-designed cardiovascular intervention trials. Notwithstanding, understanding the molecular mechanisms by which PPARα works will enable control of its activities as a drug target for metabolic diseases with an underlying inflammatory component. Given its role in reshaping the immune system, the full potential of this nuclear receptor subtype as a versatile drug target with high plasticity becomes increasingly clear, and a novel generation of agonists may pave the way for novel fields of applications.

Peroxisome proliferator-activated receptor γ (PPARγ) induces the gene expression of integrin αVβ5 to promote macrophage M2 polarization

Peroxisome proliferator-activated receptor γ (PPARγ) is a member of the nuclear receptor superfamily and polarizes the macrophages into an anti-inflammatory M2 state. Integrins are transmembrane receptors that drive various cellular functions, including monocyte adhesion and foam cell formation. In this study, we first reported that the expression of integrins α_V and β₅ was up-regulated by PPARγ activation in RAW264.7 cells and human peripheral blood monocytes. Luciferase reporter and ChIP assay revealed that PPARγ directly bound to the potential PPAR-responsive elements sites in the 5'-flanking regions of both murine and human integrin α_V and β₅ genes, respectively. In addition, we showed that PPARγ augmented the ligation of integrins α_V and β₅ Knockdown of integrin α_Vβ₅ by siRNA strategy or treatment with cilengitide, a potent inhibitor of integrin α_Vβ₅, attenuated PPARγ-induced expression of Ym1 (chitinase-like protein 3), Arg1 (Arginase1), Fizz1 (resistin-like molecule RELMα), and other M2 marker genes, suggesting that the heterodimers of integrin α_Vβ₅ were involved in PPARγ-induced M2 polarization. In conclusion, these results provided novel evidence that PPARγ-mediated gene expression and the ensuing ligation of integrins α_V and β₅ are implicated in macrophage M2 polarization.

The Pathogenesis of Diabetes Mellitus by Oxidative Stress and Inflammation: Its Inhibition by Berberine

A substantial knowledge on the pathogenesis of diabetes mellitus (DM) by oxidative stress and inflammation is available. Berberine is a biologically active botanical that can combat oxidative stress and inflammation and thus ameliorate DM, especially type 2 DM. This article describes the potential of berberine against oxidative stress and inflammation with special emphasis on its mechanistic aspects. In diabetic animal studies, the modified levels of proinflammatory cytokines and oxidative stress markers were observed after administering berberine. In renal, fat, hepatic, pancreatic and several others tissues, berberine-mediated suppression of oxidative stress and inflammation was noted. Berberine acted against oxidative stress and inflammation through a very complex mechanism consisting of several kinases and signaling pathways involving various factors, including NF-κB (nuclear factor-κB) and AMPK (AMP-activated protein kinases). Moreover, MAPKs (mitogen-activated protein kinases) and Nrf2 (nuclear factor erythroid-2 related factor 2) also have mechanistic involvement in oxidative stress and inflammation. In spite of above advancements, the mechanistic aspects of the inhibitory role of berberine against oxidative stress and inflammation in diabetes mellitus still necessitate additional molecular studies. These studies will be useful to examine the new prospects of natural moieties against DM.

The feedback loop between miR-21, PDCD4 and AP-1 functions as a driving force for renal fibrogenesis

Renal fibrosis is a final common pathway of chronic kidney disease. Sustained activation of fibroblasts is considered to play a key role in perpetuating renal fibrosis but the driving force in the perpetuation stage is only partially understood. To date, some investigations have specifically identified overexpression of microRNA 21 (miR-21) in the progression of kidney fibrosis. Nevertheless, the precise role of miR-21 in fibroblast activation remains largely unknown. In this study, we found that miR-21 was significantly upregulated in activated fibroblasts and that it maintained itself at constant high levels by employing an auto-regulatory loop between miR-21, PDCD4 and AP-1. Persistently upregulated miR-21 suppressed protein expression of Smad7 and, eventually, enhanced the TGF-β1/Smad pathway to promote fibroblast activation. More importantly, we found miR-21 sequestration with miR-21 antagomir or AP-1 inhibitors attenuated unilateral ureteral obstruction (UUO)-induced renal fibrosis. miR-21-knockout mice also suffered far less interstitial fibrosis in response to kidney injury. Altogether, these data suggest that miR-21 is a main driving force of fibroblast activation and keeps its high expression level by employing a double negative autoregulatory loop. Targeting this aberrantly activated feedback loop may provide new therapeutic strategy in treating fibrotic kidneys.

Vascular smooth muscle cell peroxisome proliferator-activated receptor γ protects against endothelin-1-induced oxidative stress and inflammation

AIMS

Peroxisome proliferator-activated receptor γ (PPARγ) agonists reduce blood pressure and vascular injury in hypertensive rodents. Pparγ inactivation in vascular smooth muscle cells (VSMC) enhances vascular injury. Transgenic mice overexpressing endothelin (ET)-1 selectively in the endothelium (eET-1) exhibit endothelial dysfunction, increased oxidative stress and inflammation. We hypothesized that inactivation of the Pparγ gene in VSMC (smPparγ-/-) would exaggerate ET-1-induced vascular injury.

METHODS AND RESULTS

eET-1, smPparγ-/- and eET-1/smPparγ-/- mice were treated with tamoxifen for 5 days and studied 4 weeks later. SBP was higher in eET-1 and unaffected by smPparγ inactivation. Mesenteric artery vasodilatory responses to acetylcholine were impaired only in smPparγ-/-. N(omega)-Nitro-L-arginine methyl ester abrogated relaxation responses, and the Ednra/Ednrb mRNA ratio was decreased in eET-1/smPparγ-/-, which could indicate that nitric oxide production was enhanced by ET-1 stimulation of endothelin type B receptors. Mesenteric artery media/lumen was greater only in eET-1/smPparγ-/-. Mesenteric artery reactive oxygen species increased in smPparγ and were further enhanced in eET-1/smPparγ-/-. Perivascular fat monocyte/macrophage infiltration was higher in eET-1 and smPparγ and increased further in eET-1/smPparγ-/-. Spleen CD11b+ cells were increased in smPparγ-/- and further enhanced in eET-1/smPparγ-/-, whereas Ly-6C(hi) monocytes increased in eET-1 and smPparγ-/- but not in eET-1/smPparγ-/-. Spleen T regulatory lymphocytes increased in smPparγ and decreased in eET-1, and decreased further in eET-1/smPparγ-/-.

CONCLUSION

VSMC Pparγ inactivation exaggerates ET-1-induced vascular injury, supporting a protective role for PPARγ in hypertension through modulation of pro-oxidant and proinflammatory pathways. Paradoxically, ET-1 overexpression preserved endothelial function in smPparγ-/- mice, presumably by enhancing nitric oxide through stimulation of endothelin type B receptors.

Adipose triglyceride lipase decrement affects skeletal muscle homeostasis during aging through FAs-PPARα-PGC-1α antioxidant response

During aging skeletal muscle shows an accumulation of oxidative damage as well as intramyocellular lipid droplets (IMLDs). However, although the impact of these modifications on muscle tissue physiology is well established, the direct effectors critical for their occurrence are poorly understood. Here we show that during aging the main lipase of triacylglycerols, ATGL, significantly declines in gastrocnemius and its downregulation in C2C12 myoblast leads to the accumulation of lipid droplets. Indeed, we observed an increase of oxidative damage to proteins in terms of carbonylation, S-nitrosylation and ubiquitination that is dependent on a defective antioxidant cell response mediated by ATGL-PPARα-PGC-1α. Overall our findings describe a pivotal role for ATGL in the antioxidant/anti-inflammatory response of muscle cells highlighting this lipase as a therapeutic target for fighting the progressive decline in skeletal muscle mass and strength.

PPARγ agonists: Potential treatments for exudative age-related macular degeneration

Choroidal neovascularization (CNV) characterizes the progression of exudative age-related macular degeneration (AMD) with the deterioration in the central vision. Vascular inflammation, and overproduction of inflammatory cytokines, growth factors and aberrant endothelial cell migration, initiate defective blood vessel proliferation in exudative AMD. CNV formation is initiated by the interplay between inflammation, the hallmark of exudative AMD, and the activation of WNT/β-catenin pathway. Upregulation of WNT/β-catenin pathway involves activation of PI3K/Akt pathway and then the Warburg effect to produce lactate. Lactate production generates VEGF expression and then participates to the initiation of CNV in exudative AMD. WNT/β-catenin pathway and PPARγ act in an opposite manner in several diseases. We focus this review on the interplay between PPARγ and canonical WNT/β-catenin pathway and the anti-inflammatory role of PPARγ in exudative AMD. In exudative AMD, PPARγ agonists downregulate inflammation and the WNT/β-catenin pathway. PPARγ agonists can appear as promising treatment against the initiation and the progression of CNV in exudative AMD.

Effect of vitamin D on isoprenaline-induced myocardial infarction in rats: possible role of peroxisome proliferator-activated receptor-γ

Infarct-like lesion induced by isoprenaline is a well-known model to study myocardial infarction (MI). Vitamin D has been shown to have anti-inflammatory and antioxidant effects. Recent studies highlighted cross talk between vitamin D and peroxisome proliferator-activated receptor gamma (PPAR-γ). The present study was designed to investigate the effect of pretreatment with vitamin D on the isoprenaline-induced infarct-like lesion in rats and the role of PPAR-γ as a novel mechanism in vitamin-D-mediated cardioprotective effect. Markers chosen to assess cardiac damage included serum level of creatine kinase (CK), lactate dehydrogenase (LDH), tumor necrosis factor-alpha (TNF-α), and interleukin-6 (IL-6). Cardiac contents of malondialdehyde (MDA), superoxide dismutase (SOD), and glutathione peroxidase (GSH) were also assessed. Furthermore, ECG monitoring and measurement of injury extension were carried out. Isoprenaline increased the level of cardiac enzymes, as well as inflammatory and oxidative stress biomarkers. In addition, it produced ST-segment elevation. Pretreatment with vitamin D significantly improved previous parameters. The prior treatment with bisphenol A diglycidyl ether (BADGE), a PPAR-γ antagonist, significantly attenuated the protective effect of vitamin D. In conclusion, vitamin D can be demonstrated as a promising cardioprotective agent in MI and PPAR-γ significantly contributes toward vitamin-D-mediated protection.

Pathogenic Role of microRNA-21 in Diabetic Retinopathy Through Downregulation of PPARα

Fenofibrate, a specific agonist of peroxisome proliferator-activated receptor-α (PPARα), displays robust therapeutic effects on diabetic retinopathy (DR) in patients with type 2 diabetes. Our recent studies have shown that PPARα is downregulated in the diabetic retina, which contributes to the pathogenesis of DR. However, the mechanism for diabetes-induced downregulation of PPARα remains unknown. We investigated the role of microRNA-21 (miR-21) in regulating PPARα in DR. miR-21 was overexpressed, while PPARα levels were decreased in the retina of db/db mice, a model of type 2 diabetes. Such alterations were also observed in palmitate-treated retinal endothelial cells. miR-21 targeted PPARα by inhibiting its mRNA translation. Knockout of miR-21 prevented the decrease of PPARα, alleviated microvascular damage, ameliorated inflammation, and reduced cell apoptosis in the retina of db/db mice. Intravitreal injection of miR-21 inhibitor attenuated PPARα downregulation and ameliorated retinal inflammation in db/db mice. Further, retinal miR-21 levels were increased, while PPARα levels were decreased in oxygen-induced retinopathy (OIR). Knockout of miR-21 prevented PPARα downregulation and ameliorated retinal neovascularization and inflammation in OIR retinas. In conclusion, diabetes-induced overexpression of miR-21 in the retina is at least partly responsible for PPARα downregulation in DR. Targeting miR-21 may represent a novel therapeutic strategy for DR.

Is spaceflight-induced immune dysfunction linked to systemic changes in metabolism?

The Space Shuttle Atlantis launched on its final mission (STS-135) on July 8, 2011. After just under 13 days, the shuttle landed safely at Kennedy Space Center (KSC) for the last time. Female C57BL/6J mice flew as part of the Commercial Biomedical Testing Module-3 (CBTM-3) payload. Ground controls were maintained at the KSC facility. Subsets of these mice were made available to investigators as part of NASA’s Bio-specimen Sharing Program (BSP). Our group characterized cell phenotype distributions and phagocytic function in the spleen, catecholamine and corticosterone levels in the adrenal glands, and transcriptomics/metabolomics in the liver. Despite decreases in most splenic leukocyte subsets, there were increases in reactive oxygen species (ROS)-related activity. Although there were increases noted in corticosterone levels in both the adrenals and liver, there were no significant changes in catecholamine levels. Furthermore, functional analysis of gene expression and metabolomic profiles suggest that the functional changes are not due to oxidative or psychological stress. Despite changes in gene expression patterns indicative of increases in phagocytic activity (e.g. endocytosis and formation of peroxisomes), there was no corresponding increase in genes related to ROS metabolism. In contrast, there were increases in expression profiles related to fatty acid oxidation with decreases in glycolysis-related profiles. Given the clear link between immune function and metabolism in many ground-based diseases, we propose a similar link may be involved in spaceflight-induced decrements in immune and metabolic function.

In vivo activation of invariant natural killer T cells induces systemic and local alterations in T-cell subsets prior to preterm birth

Preterm birth, the leading cause of neonatal morbidity and mortality worldwide, is frequently preceded by spontaneous preterm labour, a syndrome of multiple aetiologies. Pathological inflammation is causally linked to spontaneous preterm labour. Indeed, direct activation of invariant natural killer T (iNKT) cells via α-galactosylceramide induces preterm labour/birth largely by initiating systemic and local (i.e. decidua and myometrium) innate immune responses. Herein, we investigated whether iNKT-cell activation altered local and systemic T-cell subsets. Administration of α-galactosylceramide induced an expansion of activated CD1d-restricted iNKT cells in the decidua and a reduction in the number of: (1) total T cells (conventional CD4⁺ and CD8⁺ T cells) through the down-regulation of the CD3ɛ molecule in the peripheral circulation, spleen, uterine-draining lymph nodes (ULNs), decidua and/or myometrium; (2) CD4⁺ regulatory T cells in the spleen, ULNs and decidua; (3) T helper type 17 (Th17) cells in the ULNs but an increase in the number of decidual Th17 cells; (4) CD8⁺ regulatory T cells in the spleen and ULNs; and (5) CD4⁺ and CD8⁺ forkhead box protein 3 negative (Foxp3^- ) responder T cells in the spleen and ULNs. As treatment with rosiglitazone prevents iNKT-cell activation-induced preterm labour/birth, we also explored whether the administration of this peroxisome proliferator-activated receptor gamma (PPARγ) agonist would restore the number of T cells. Treating α-galactosylceramide-injected mice with rosiglitazone partially restored the number of T cells in the spleen but not in the decidua. In summary, iNKT-cell activation altered the systemic and local T-cell subsets prior to preterm labour/birth; however, treatment with rosiglitazone partially reversed such effects.

Retinol-binding protein 7 is an endothelium-specific PPAR cofactor mediating an antioxidant response through adiponectin

Impaired PPARγ activity in endothelial cells causes oxidative stress and endothelial dysfunction which causes a predisposition to hypertension, but the identity of key PPARγ target genes that protect the endothelium remain unclear. Retinol-binding protein 7 (RBP7) is a PPARγ target gene that is essentially endothelium specific. Whereas RBP7-deficient mice exhibit normal endothelial function at baseline, they exhibit severe endothelial dysfunction in response to cardiovascular stressors, including high-fat diet and subpressor angiotensin II. Endothelial dysfunction was not due to differences in weight gain, impaired glucose homeostasis, or hepatosteatosis, but occurred through an oxidative stress-dependent mechanism which can be rescued by scavengers of superoxide. RNA sequencing revealed that RBP7 was required to mediate induction of a subset of PPARγ target genes by rosiglitazone in the endothelium including adiponectin. Adiponectin was selectively induced in the endothelium of control mice by high-fat diet and rosiglitazone, whereas RBP7 deficiency abolished this induction. Adiponectin inhibition caused endothelial dysfunction in control vessels, whereas adiponectin treatment of RBP7-deficient vessels improved endothelium-dependent relaxation and reduced oxidative stress. We conclude that RBP7 is required to mediate the protective effects of PPARγ in the endothelium through adiponectin, and RBP7 is an endothelium-specific PPARγ target and regulator of PPARγ activity.

DHA blocks TPA-induced cell invasion by inhibiting MMP-9 expression via suppression of the PPAR-γ/NF-κB pathway in MCF-7 cells

Docosahexaenoic acid (DHA) is an omega-3 fatty acid that is considered to have applications in cancer prevention and treatment. The beneficial effects of DHA against cancer metastasis are well established; however, the mechanisms underlying these effects in breast cancer are not clear. Cell invasion is critical for neoplastic metastasis, and involves the degradation of the extracellular matrix by matrix metalloproteinase (MMP)-9. The present study investigated the inhibitory effect of DHA on MMP-9 expression and cell invasion induced by 12-O-tetradecanoylphorbol-13-acetate (TPA) in the MCF-7 breast cancer cell line. DHA inhibited the TPA-induced activation of mitogen-activated protein kinase (MAPK) and the transcription of nuclear factor (NF)-κB, but did not inhibit the transcription of activator protein-1. DHA increased the activity of peroxisome proliferator-activated receptor (PPAR)-γ, an effect that was reversed by the application of the PPAR-γ antagonist GW9662. In addition, combined treatment with GW9662 and DHA increased NF-κB-related protein expression. These results indicate that DHA regulates MMP-9 expression and cell invasion via modulation of the MAPK signaling pathway and PPAR-γ/NF-κB activity. This suggests that DHA could be a potential therapeutic agent for the prevention of breast cancer metastasis.

Continuous Intravenous Administration of a Low Dose of Epoprostenol Greatly Decreased Serum Concentrations of Endothelin-1 in Primary Pulmonary Hypertension

Endothelin-1 (ET-1) is known to be a principal factor in the pathogenesis of primary pulmonary hypertension (PPH). Recently intravenous administration of epoprosterol improved the survival rate in PPH. However, the effect of epoprosterol on ET-1 remains to be investigated. Therefore, we studied a patient with PPH who was treated with a low dose of epoprosterol and examined the serum concentration of ET-1 during the treatment. Epoprosterol greatly decreased the serum concentration of ET-1 in parallel with improvement of the clinical course, suggesting that ET-1 level may be a marker for treatment of PPH.

Review: Vascular protective effects of peroxisome proliferator-activated receptor agonists

ardiovascular disease is significantly increased in patients with the metabolic syndrome and type 2 diabetes. A clustering of risk factors, including dyslipidaemia, insulin resistance, hypertension, inflammation and coagulation disorders are acting in concert to promote cardiovascular events in these patients. Peroxisome proliferator-activated receptors (PPARs) are transcription factors that influence vascular function by altering gene expression in vascular tissue and indirectly via effects on other tissues. Indeed, PPAR activation displays beneficial effects on glucose homeostasis and lipid metabolism, and also on endothelial function and vessel wall inflammation. Clinically used PPARα agonists, such as fibrates, and PPARγ agonists, such as insulin-sensitising thiazolidinediones, may consequently alter the process of atherosclerosis, especially in subjects with the metabolic syndrome and type 2 diabetes. The present review highlights emerging evidence for beneficial effects of PPAR α and PPARγ in the prevention and treatment of atherosclerosis in such high-risk patients.

Cardioprotective role of peroxisome proliferator-activated receptor-γ agonist, rosiglitazone in a unique murine model of diabetic cardiopathy

AIMS

Rosiglitazone (RSZ), a PPARγ agonist was potent efficacious insulin sensitizing blockbuster drug for treatment of Type 2 diabetes mellitus (T2DM) but the benefit of PPARγ activation in congestive heart failure (CHF) was controversial. The present work was planned to study the role of RSZ in diabetic cardiopathy.

MAIN METHODS

Zucker fa/fa rats, the genetic model of T2DM were subjected to constriction of suprarenal abdominal aorta so that they represent a combined model of diabetes and cardiopathy. The development cardiopathy was assessed biochemically (plasma BNP and aldosterone levels), using echocardiography and expression angiotensin II receptor type 1a gene in heart and Endothelin-1 gene in aorta. Rats were treated with RSZ and in combination with amiloride for four weeks and were assessed to evaluate the effect of RSZ or amiloride or its combination on antidiabetic activity, adverse or toxic effects and congestive heart failure status.

KEY FINDINGS

RSZ shows its anti-diabetic effect from 0.3mg/kg dose onwards and at 3mg/kg dose levels it caused beneficial effects (reduction of blood pressure) on cardiovascular system and at highest (30mg/kg) dose it starts showing adverse effects like body weight gain, edema, left ventricular hypertrophy. However, when highest dose of RSZ animals were treated with amiloride (ENaC inhibitor) at 2mg/kg the reversal of the adverse effects was evident, indicating the combination of RSZ and amiloride is beneficial in diabetic cardiopathy model.

SIGNIFICANCE

RSZ and amiloride combination appeared promising treatment in diabetic patients with cardiopathy without any side effect.

An M1-like Macrophage Polarization in Decidual Tissue during Spontaneous Preterm Labor That Is Attenuated by Rosiglitazone Treatment

Decidual macrophages are implicated in the local inflammatory response that accompanies spontaneous preterm labor/birth; however, their role is poorly understood. We hypothesized that decidual macrophages undergo a proinflammatory (M1) polarization during spontaneous preterm labor and that PPARγ activation via rosiglitazone (RSG) would attenuate the macrophage-mediated inflammatory response, preventing preterm birth. In this study, we show that: 1) decidual macrophages undergo an M1-like polarization during spontaneous term and preterm labor; 2) anti-inflammatory (M2)-like macrophages are more abundant than M1-like macrophages in decidual tissue; 3) decidual M2-like macrophages are reduced in preterm pregnancies compared with term pregnancies, regardless of the presence of labor; 4) decidual macrophages express high levels of TNF and IL-12 but low levels of peroxisome proliferator-activated receptor γ (PPARγ) during spontaneous preterm labor; 5) decidual macrophages from women who underwent spontaneous preterm labor display plasticity by M1↔M2 polarization in vitro; 6) incubation with RSG reduces the expression of TNF and IL-12 in decidual macrophages from women who underwent spontaneous preterm labor; and 7) treatment with RSG reduces the rate of LPS-induced preterm birth and improves neonatal outcomes by reducing the systemic proinflammatory response and downregulating mRNA and protein expression of NF-κB, TNF, and IL-10 in decidual and myometrial macrophages in C57BL/6J mice. In summary, we demonstrated that decidual M1-like macrophages are associated with spontaneous preterm labor and that PPARγ activation via RSG can attenuate the macrophage-mediated proinflammatory response, preventing preterm birth and improving neonatal outcomes. These findings suggest that the PPARγ pathway is a new molecular target for future preventative strategies for spontaneous preterm labor/birth.

Plaque Thrombosis is Reduced by Attenuating Plaque Inflammation with Pioglitazone and is Evaluated by Fluorodeoxyglucose Positron Emission Tomography

INTRODUCTION

The relationship between the beneficial effects of pioglitazone in reducing clinical events and plaque inflammatory burden remains unknown. This study aimed to determine whether pioglitazone can reduce the number of plaque thrombosis incidences and whether decreasing plaque inflammation is the mechanism by which pioglitazone reduces plaque thromboses.

METHODS AND RESULTS

therosclerotic rabbits were divided into two groups: the atherosclerosis group (n = 13) and pioglitazone group (n = 10). The rabbits underwent pharmacological triggering to induce thrombosis. Serum inflammatory markers, FDG uptake, macrophage, and neovessel staining detected arterial inflammation. PET/CT scans were performed twice (baseline and posttreatment scans). Plaque area, macrophages, and neovessels were measured and the histologic sections were matched with the PET/CT scans. Serum MMP-9 and hsCRP were lower in the pioglitazone group compared to the atherosclerosis group. The SUVmean significantly decreased in the pioglitazone group (0.62 ± 0.21 vs. 0.55 ± 0.19, P = 0.008), but increased in the atherosclerosis group (0.61 ± 0.15 vs. 0.91 ± 0.20, P < 0.000). The incidence rate of plaque rupture, plaque area, macrophage density, and neovessel density was significantly lower in rabbits with pioglitazone than without (15% vs. 38%, P < 0.001; 18.00 ± 2.30 vs. 27.00 ± 1.60; P < 0.001; 8.80 ± 3.94 vs. 28.26 ± 2.49; P < 0.001; 16.50 ± 3.09 vs. 29.00 ± 2.11; P < 0.001, respectively). Moreover, plaque area and macrophage density were positively correlated with SUV values.

CONCLUSIONS

Our study suggests that pioglitazone can reduce the number of plaque thrombosis incidences by decreasing plaque inflammation. (18)F-FDG-PET/CT can detect plaque inflammation and assess the effects of antiatherosclerotic drugs.

Invariant NKT Cell Activation Induces Late Preterm Birth That Is Attenuated by Rosiglitazone

Preterm birth (PTB) is the leading cause of neonatal morbidity and mortality worldwide. Although intra-amniotic infection is a recognized cause of spontaneous preterm labor, the noninfection-related etiologies are poorly understood. In this article, we demonstrated that the expansion of activated CD1d-restricted invariant NKT (iNKT) cells in the third trimester by administration of α-galactosylceramide (α-GalCer) induced late PTB and neonatal mortality. In vivo imaging revealed that fetuses from mice that underwent α-GalCer-induced late PTB had bradycardia and died shortly after delivery. Yet, administration of α-GalCer in the second trimester did not cause pregnancy loss. Peroxisome proliferator-activated receptor (PPAR)γ activation, through rosiglitazone treatment, reduced the rate of α-GalCer-induced late PTB and improved neonatal survival. Administration of α-GalCer in the third trimester suppressed PPARγ activation, as shown by the downregulation of Fabp4 and Fatp4 in myometrial and decidual tissues, respectively; this suppression was rescued by rosiglitazone treatment. Administration of α-GalCer in the third trimester induced an increase in the activation of conventional CD4(+) T cells in myometrial tissues and the infiltration of activated macrophages, neutrophils, and mature dendritic cells to myometrial and/or decidual tissues. All of these effects were blunted after rosiglitazone treatment. Administration of α-GalCer also upregulated the expression of inflammatory genes at the maternal-fetal interface and systemically, and rosiglitazone treatment partially attenuated these responses. Finally, an increased infiltration of activated iNKT-like cells in human decidual tissues is associated with noninfection-related preterm labor/birth. Collectively, these results demonstrate that iNKT cell activation in vivo leads to late PTB by initiating innate and adaptive immune responses and suggest that the PPARγ pathway has potential as a target for prevention of this syndrome.

PPARβ/δ and lipid metabolism in the heart

Cardiac lipid metabolism is the focus of attention due to its involvement in the development of cardiac disorders. Both a reduction and an increase in fatty acid utilization make the heart more prone to the development of lipotoxic cardiac dysfunction. The ligand-activated transcription factor peroxisome proliferator-activated receptor (PPAR)β/δ modulates different aspects of cardiac fatty acid metabolism, and targeting this nuclear receptor can improve heart diseases caused by altered fatty acid metabolism. In addition, PPARβ/δ regulates glucose metabolism, the cardiac levels of endogenous antioxidants, mitochondrial biogenesis, cardiomyocyte apoptosis, the insulin signaling pathway and lipid-induced myocardial inflammatory responses. As a result, PPARβ/δ ligands can improve cardiac function and ameliorate the pathological progression of cardiac hypertrophy, heart failure, cardiac oxidative damage, ischemia-reperfusion injury, lipotoxic cardiac dysfunction and lipid-induced cardiac inflammation. Most of these findings have been observed in preclinical studies and it remains to be established to what extent these intriguing observations can be translated into clinical practice. This article is part of a Special Issue entitled: Heart Lipid Metabolism edited by G.D. Lopaschuk.

Peroxisome proliferator-activated receptors (PPAR) downregulate the expression of pro-inflammatory molecules in an experimental model of myocardial infarction

Myocardial infarction (MI) has been associated with an inflammatory response and a rise in TNF-α, interleukin (IL)-1β, and IL-6. Peroxisome proliferator-activated receptors (PPARs) promote a decreased expression of inflammatory molecules. We aimed to study whether PPAR stimulation by clofibrate decreases inflammation and reduces infarct size in rats with MI. Male Wistar rats were randomized into 3 groups: control, MI + vehicle, and MI + clofibrate (100 mg/kg). Treatment was administered for 3 consecutive days, previous to 2 h of MI. MI induced an increase in protein expression, mRNA content, and enzymatic activity of inducible nitric oxide synthase (iNOS). Additionally, MI incited an increased expression of matrix metalloproteinase (MMP)-2 and MMP-9, intercellular adhesion molecule (ICAM)-1, and IL-6. MI also elevated the nuclear content of nuclear factor-κB (NF-κB) and decreased IκB, both in myocyte nuclei and cytosol. Clofibrate treatment prevented MI-induced changes in iNOS, MMP-2 and MMP-9, ICAM-1, IL-6, NF-κB, and IκB. Infarct size was smaller in clofibrate-treated rats compared to MI-vehicle animals. In silico analysis exhibited 3 motifs shared by genes from renin-angiotensin system, PPARα, iNOS, MMP-2 and MMP-9, ICAM-1, and VCAM-1, suggesting a cross regulation. In conclusion, PPARα-stimulation prevents overexpression of pro-inflammatory molecules and preserves viability in an experimental model of acute MI.

Berberine and Its Role in Chronic Disease

Berberine is a quaternary ammonium salt from the protoberberine group of isoquinoline alkaloids. It is found in such plants as Berberis [e.g. Berberis aquifolium (Oregon grape), Berberis vulgaris (barberry), Berberis aristata (tree turmeric)], Hydrastis canadensis (goldenseal), Xanthorhiza simplicissima (yellowroot), Phellodendron amurense ^[2] (Amur corktree), Coptis chinensis (Chinese goldthread), Tinospora cordifolia, Argemone mexicana (prickly poppy) and Eschscholzia californica (Californian poppy). In vitro it exerts significant anti-inflammatory and antioxidant activities. In animal models berberine has neuroprotective and cardiovascular protective effects. In humans, its lipid-lowering and insulin-resistance improving actions have clearly been demonstrated in numerous randomized clinical trials. Moreover, preliminary clinical evidence suggest the ability of berberine to reduce endothelial inflammation improving vascular health, even in patients already affected by cardiovascular diseases. Altogether the available evidences suggest a possible application of berberine use in the management of chronic cardiometabolic disorders.