Macrophages in human atheroma contain PPARgamma: differentiation-dependent peroxisomal proliferator-activated receptor gamma(PPARgamma) expression and reduction of MMP-9 activity through PPARgamma activation in mononuclear phagocytes in vitro

Arachidonic acid-derived lipid mediators in multiple sclerosis pathogenesis: fueling or dampening disease progression?

BACKGROUND

Multiple sclerosis (MS) is a chronic autoimmune disease of the central nervous system (CNS), characterized by neuroinflammation, demyelination, and neurodegeneration. Considering the increasing prevalence among young adults worldwide and the disabling phenotype of the disease, a deeper understanding of the complexity of the disease pathogenesis is needed to ultimately improve diagnosis and personalize treatment opportunities. Recent findings suggest that bioactive lipid mediators (LM) derived from ω-3/-6 polyunsaturated fatty acids (PUFA), also termed eicosanoids, may contribute to MS pathogenesis. For example, disturbances in LM profiles and especially those derived from the ω-6 PUFA arachidonic acid (AA) have been reported in people with MS (PwMS), where they may contribute to the chronicity of neuroinflammatory processes. Moreover, we have previously shown that certain AA-derived LMs also associated with neurodegenerative processes in PwMS, suggesting that AA-derived LMs are involved in more pathological events than solely neuroinflammation. Yet, to date, a comprehensive overview of the contribution of these LMs to MS-associated pathological processes remains elusive.

MAIN BODY

This review summarizes and critically evaluates the current body of literature on the eicosanoid biosynthetic pathway and its contribution to key pathological hallmarks of MS during different disease stages. Various parts of the eicosanoid pathway are highlighted, namely, the prostanoid, leukotriene, and hydroxyeicosatetraenoic acids (HETEs) biochemical routes that include specific enzymes of the cyclooxygenases (COXs) and lipoxygenases (LOX) families. In addition, cellular sources of LMs and their potential target cells based on receptor expression profiles will be discussed in the context of MS. Finally, we propose novel therapeutic approaches based on eicosanoid pathway and/or receptor modulation to ultimately target chronic neuroinflammation, demyelination and neurodegeneration in MS.

SHORT CONCLUSION

The eicosanoid pathway is intrinsically linked to specific aspects of MS pathogenesis. Therefore, we propose that novel intervention strategies, with the aim of accurately modulating the eicosanoid pathway towards the biosynthesis of beneficial LMs, can potentially contribute to more patient- and MS subtype-specific treatment opportunities to combat MS.

Surfactant protein A promotes atherosclerosis through mediating macrophage foam cell formation

BACKGROUND

Atherosclerosis is a progressive inflammatory disease where macrophage foam cells play a central role in the pathogenesis. Surfactant protein A (SPA) is a lipid-associating protein involved with regulating macrophage function in various inflammatory diseases. However, the role of SPA in atherosclerosis and macrophage foam cell formation has not been investigated.

METHODS

Primary resident peritoneal macrophages were extracted from wildtype (WT) and SPA deficient (SPA -/- ) mice to determine the functional effects of SPA in macrophage foam cell formation. SPA expression was assessed in healthy vessels and atherosclerotic aortic tissue from the human coronary artery and WT or apolipoprotein e-deficient (ApoE -/- ) mice brachiocephalic arteries fed high fat diets (HFD) for 4 weeks. Hypercholesteremic WT and SPA -/- mice fed a HFD for 6 weeks were investigated for atherosclerotic lesions in vivo .

RESULTS

In vitro experiments revealed that global SPA deficiency reduced intracellular cholesterol accumulation and macrophage foam cell formation. Mechanistically, SPA -/- dramatically decreased CD36 cellular and mRNA expression. SPA expression was increased in atherosclerotic lesions in humans and ApoE -/- mice. In vivo SPA deficiency attenuated atherosclerosis and reduced the number of lesion-associated macrophage foam cells.

CONCLUSIONS

Our results elucidate that SPA is a novel factor for atherosclerosis development. SPA enhances macrophage foam cell formation and atherosclerosis through increasing scavenger receptor cluster of differentiation antigen 36 (CD36) expression.

Therapeutic modulation of JAK-STAT, mTOR, and PPAR-γ signaling in neurological dysfunctions

The cytokine-activated Janus kinase (JAK)-signal transducer and activator of transcription (STAT) cascade is a pleiotropic pathway that involves receptor subunit multimerization. The mammalian target of rapamycin (mTOR) is a ubiquitously expressed serine-threonine kinase that perceives and integrates a variety of intracellular and environmental stimuli to regulate essential activities such as cell development and metabolism. Peroxisome proliferator-activated receptor-gamma (PPARγ) is a prototypical metabolic nuclear receptor involved in neural differentiation and axon polarity. The JAK-STAT, mTOR, and PPARγ signaling pathways serve as a highly conserved signaling hub that coordinates neuronal activity and brain development. Additionally, overactivation of JAK/STAT, mTOR, and inhibition of PPARγ signaling have been linked to various neurocomplications, including neuroinflammation, apoptosis, and oxidative stress. Emerging research suggests that even minor disruptions in these cellular and molecular processes can have significant consequences manifested as neurological and neuropsychiatric diseases. Of interest, target modulators have been proven to alleviate neuronal complications associated with acute and chronic neurological deficits. This research-based review explores the therapeutic role of JAK-STAT, mTOR, and PPARγ signaling modulators in preventing neuronal dysfunctions in preclinical and clinical investigations.

CDDO, a PPAR‑γ ligand, inhibits TPA‑induced cell migration and invasion through a PPAR‑γ‑independent mechanism

Peroxisome proliferator-activated receptor-γ (PPAR-γ) acts as a key factor in breast cancer metastasis. Notably, PPAR-γ can inhibit metalloproteinase (MMP), which is involved in cancer metastasis. Our previous study revealed that PPAR-γ was related to breast cancer metastasis. The present study aimed to investigate whether the PPAR-γ ligand 2-cyano-3,12-dioxooleana-1,9-dien-28-oic acid (CDDO) mediated suppression of cell invasion and reduced the expression of MMP-9 in breast cancer cells. The results indicated that CDDO reduced MMP-9 expression, cell migration and invasion of breast cancer cells by inhibiting TPA-induced phosphorylation of mitogen-activated protein kinases, and downregulating the activities of activator protein-1 and nuclear factor κB. Notably, knock-out of PPAR-γ by small interfering RNA in MCF-7 cells revealed that TPA-induced MMP-9 expression occurred through a PPAR-γ-independent pathway. These data indicated that the downregulatory effect of CDDO on MMP-9 expression was affected by a mechanism independent of PPAR-γ. In conclusion, the findings of the present study suggested that CDDO may act as a key agent in the regulation of breast cancer metastasis, suggesting CDDO as a new targeted therapy for breast cancer.

The Correlation Between Peroxisome Proliferator-Activated Receptor Alpha and Gamma Polymorphisms and Acute Coronary Syndrome

Objective: This study aims to evaluate the relationship between peroxisome proliferator-activated receptor (PPAR) alpha and gamma gene polymorphisms and acute coronary syndrome (ACS) clinically.

Subject and methods: Peripheral blood samples were collected from a total of 200 people, including 100 acute coronary syndrome patients and 100 controls aged 19 to 93 years, admitted to the Pamukkale University Emergency Medicine Department. The healthy volunteers had no known chronic or acute diseases, no history of drug use, and no recent history of coronary artery disease (CAD). PPAR alpha L162V and PPAR gamma C161T gene polymorphic regions were detected using DNA sequencing analyses. In addition, data collected from the hemogram and biochemical parameters and comorbidities of the patients were statistically analyzed.

Results: PPAR gamma C161T polymorphisms were compared between groups. The CT heterozygous rate in the patient group (74%) was higher than in the control group (7%). The T allele was more common in the patient group (0.37) compared to the control group (0.03). When PPAR alpha L162V polymorphism was compared, VV homozygous individuals were %19 in the patient group and none in the control group. The V allele was found to be statistically higher in patients with ACS (p<0.01).

Conclusion: The findings revealed that elevated PPAR alpha L162V and PPAR gamma C161T gene polymorphisms were associated with a progressive risk of ACS.

Advancing the Adverse Outcome Pathway for PPARγ Inactivation Leading to Pulmonary Fibrosis Using Bradford-Hill Consideration and the Comparative Toxicogenomics Database

Pulmonary fibrosis is regulated by transforming growth factor-β (TGF-β) and peroxisome proliferator-activated receptor-gamma (PPARγ). An adverse outcome pathway (AOP) for PPARγ inactivation leading to pulmonary fibrosis has been previously developed. To advance the development of this AOP, the confidence of the overall AOP was assessed using the Bradford-Hill considerations as per the recommendations from the Organisation for Economic Co-operation and Development (OECD) Users' Handbook. Overall, the essentiality of key events (KEs) and the biological plausibility of key event relationships (KERs) were rated high. In contrast, the empirical support of KERs was found to be moderate. To experimentally evaluate the KERs from the molecular initiating event (MIE) and KE1, PPARγ (MIE) and TGF-β (KE1) inhibitors were used to examine the effects of downstream events following inhibition of their upstream events. PPARγ inhibition (MIE) led to TGF-β activation (KE1), upregulation in vimentin expression (KE3), and an increase in the fibronectin level (KE4). Similarly, activated TGF-β (KE1) led to an increase in vimentin (KE3) and fibronectin expression (KE4). In the database analysis using the Comparative Toxicogenomics Database, 31 genes related to each KE were found to be highly correlated with pulmonary fibrosis, and the top 21 potential stressors were suggested. The AOP for pulmonary fibrosis evaluated in this study will be the basis for the screening of inhaled toxic substances in the environment.

Evaluation of the action of LPSF/GQ-16 on cytokines and PPAR-γ gene expression after in vitro irradiation of peripheral blood mononuclear cells

PURPOSE

Patients submitted to radiotherapy (RT) may present in their healthy tissues surrounding the treated tumor, some typical acute inflammatory reactions induced by ionizing radiation (IR). The manifestation of inflammatory processes is a result of exacerbation of the immune system, as a response to radiation exposure, and this can be a limiting factor for RT protocols. To counteract this, some thiazolidinediones, such as LPSF/GQ-16, may be useful for modulating the patient's radioinduced inflammatory response in normal tissues. In this context, the present work aims to evaluate the activity of LPSF/GQ-16 on the levels of cytokines and the expression of the gene PPARγ in mononuclear cells irradiated in vitro, to analyze the immunomodulatory activity of the molecule and its action on radiomitigation.

MATERIALS AND METHODS

For this, blood samples from eight donors were collected and irradiated with 2 Gy, then the PBMC (peripheral blood mononuclear cells) were cultured and treated with LPSF/GQ-16. The levels of cytokines TNF-α, IFN-γ, IL-2 and IL-4 were quantified by CBA, while the genes of TNF-α, IFN-γ and PPARγ were analyzed by RT-PCR.

RESULTS

LPSF/GQ-16 significantly reduced the expression of proinflammatory cytokines (IFN-γ and TNF-α) in irradiated and nonirradiated groups. There was no significant reduction of anti-inflammatory cytokines (IL-2 and IL-4) by LPSF/GQ-16. The mRNA expression of PPAR-γ, IFN-γ and TNF-α in the presence of LPSF/GQ-16 was higher in the nonirradiated sample.

CONCLUSION

LPSF/GQ-16 showed effective activity after irradiation, with an important immunomodulatory activity in irradiated PBMCs.

The Emerging Role of COX-2, 15-LOX and PPARγ in Metabolic Diseases and Cancer: An Introduction to Novel Multi-target Directed Ligands (MTDLs)

Emerging evidence supports an intertwining framework for the involvement of different inflammatory pathways in a common pathological background for a number of disorders. Of importance are pathways involving arachidonic acid metabolism by cyclooxygenase-2 (COX-2) and 15-lipoxygenase (15-LOX). Both enzyme activities and their products are implicated in a range of pathophysiological processes encompassing metabolic impairment leading to adipose inflammation and the subsequent vascular and neurological disorders, in addition to various pro- and antitumorigenic effects. A further layer of complexity is encountered by the disparate, and often reciprocal, modulatory effect COX-2 and 15-LOX activities and metabolites exert on each other or on other cellular targets, the most prominent of which is peroxisome proliferator-activated receptor gamma (PPARγ). Thus, effective therapeutic intervention with such multifaceted disorders requires the simultaneous modulation of more than one target. Here, we describe the role of COX-2, 15-LOX, and PPARγ in cancer and complications of metabolic disorders, highlight the value of designing multi-target directed ligands (MTDLs) modifying their activity, and summarizing the available literature regarding the rationale and feasibility of design and synthesis of these ligands together with their known biological effects. We speculate on the potential impact of MTDLs in these disorders as well as emphasize the need for structured future effort to translate these early results facilitating the adoption of these, and similar, molecules in clinical research.

Astragaloside IV promotes microglia/macrophages M2 polarization and enhances neurogenesis and angiogenesis through PPARγ pathway after cerebral ischemia/reperfusion injury in rats

Microglia/macrophages play a dual role in brain injury and repair following cerebral ischemia/reperfusion. Promoting microglia/macrophage polarization from pro-inflammatory M1 to anti-inflammatory M2 phenotype has been considered as a potential treatment for ischemic stroke. Astragaloside IV (AS-IV) is a primary active ingredient of Chinese herb Radix Astragali, which protects against acute cerebral ischemic/reperfusion injury through its antioxidant, anti-inflammatory, and anti-apoptotic properties. However, it remains unknown whether AS-IV improves ischemic brain tissue repair and its underlying mechanism. A transient middle cerebral artery occlusion (tMCAO) rat model was used in this study. The results showed that AS-IV significantly improved long-term brain injury, reduced the expression of M1 microglia/macrophage markers and increased the expression of M2 microglia/macrophage markers 14 days after cerebral ischemia/reperfusion. AS-IV also increased peroxisome proliferator-activated receptor γ (PPARγ) mRNA and protein expression. Moreover, AS-IV promoted neurogenesis and angiogenesis, and increased the protein expression of brain-derived growth factor (BDNF), insulin-like growth factor-1 (IGF-1) and vascular endothelial growth factor (VEGF). However, these beneficial effects were greatly blocked by PPARγ antagonist T0070907. These results together suggest that AS-IV could enhance neurogenesis, angiogenesis and neurological functional recovery, which may be partially through transforming microglia/macrophage from M1 to M2 phenotype in a PPARγ-dependent manner after cerebral ischemia/reperfusion injury. Therefore, AS-IV can be considered as a promising therapeutic agent for ischemic stroke.

Pharmacological (or Synthetic) and Nutritional Agonists of PPAR-γ as Candidates for Cytokine Storm Modulation in COVID-19 Disease

The cytokine storm is an abnormal production of inflammatory cytokines, due to the over-activation of the innate immune response. This mechanism has been recognized as a critical mediator of influenza-induced lung disease, and it could be pivotal for COVID-19 infections. Thus, an immunomodulatory approach targeting the over-production of cytokines could be proposed for viral aggressive pulmonary disease treatment. In this regard, the peroxisome proliferator-activated receptor (PPAR)-γ, a member of the PPAR transcription factor family, could represent a potential target. Beside the well-known regulatory role on lipid and glucose metabolism, PPAR-γ also represses the inflammatory process. Similarly, the PPAR-γ agonist thiazolidinediones (TZDs), like pioglitazone, are anti-inflammatory drugs with ameliorating effects on severe viral pneumonia. In addition to the pharmacological agonists, also nutritional ligands of PPAR-γ, like curcuma, lemongrass, and pomegranate, possess anti-inflammatory properties through PPAR-γ activation. Here, we review the main synthetic and nutritional PPAR-γ ligands, proposing a dual approach based on the strengthening of the immune system using pharmacological and dietary strategies as an attempt to prevent/treat cytokine storm in the case of coronavirus infection.

Assessment of COL1A1 and MMP9 expression in patients with dermatochalasis

PURPOSE

Dermatochalasis is a clinical condition characterized by loss of elasticity of eyelid skin and soft tissue, which typically affects the elderly population. The aim of this study is to investigate the mRNA expression levels of collagen type 1 alpha 1 (COL1A1) and matrix metalloproteinase-9 (MMP9) genes in dermatochalasis tissue.

METHODS

The study group consisted of 15 patients who underwent upper eyelid blepharoplasty and were above 40 years old. The patients in our control group were divided into two subgroups according to their ages. Fourteen patients who were under 40 years old and had anterior blepharoptosis surgery for blepharoptosis were designed as the young control group. Sixteen patients who were older than 40 years old and had anterior blepharoptosis surgery for blepharoptosis were designed as the old control group. The patients in the dermatochalasis group were also evaluated according to their smoking status. Surgical tissue specimens were analyzed for COL1A1 and MMP9 mRNA gene expression levels by using real-time polymerase chain reaction.

RESULTS

COL1A1 and MMP9 mRNA gene expression levels were not statistically different between the groups (p = 0.247; p = 0.052, respectively). When compared in means of the smoking habit, smokers in the dermatochalasis group exhibited higher COL1A1 mRNA expression levels when compared to nonsmokers (p = 0.008). MMP9 gene expression levels of smokers exhibited almost statistically higher levels but at the limit when compared to nonsmokers (p = 0.05).

CONCLUSIONS

This study represents a preliminary study to detect the tissue changes at a molecular level in dermatochalasis, which is known to be related to connective tissue pathology. Collagen and MMPs are essential components of the extracellular matrix, and smoking might affect their gene expression. Further prospective studies on these regulatory genes and encoded protein levels with a larger group of patients may provide particular contribution to explaining the pathophysiology of dermatochalasis.

Different Drugs Effect on Mesenchymal Stem Cells Isolated From Abdominal Aortic Aneurysm

BACKGROUND

Abdominal aortic aneurysm (AAA) is a progressive dilation of the aortic wall, determined by the unbalanced activity of matrix metalloproteinase (MMPs). In vitro and in vivo studies support the pivotal role of MMP-9 to AAA pathogenesis. In our experience, we elucidated the expression of MMP-9 in an ex vivo model of human mesenchymal stem cells isolated from AAA specimen (AAA-MSCs). Thus, MMP-9 inhibition could be an attractive therapeutic strategy for inhibiting AAA degeneration and rupture. Our study was aimed at testing the effect of 3 different drugs (pioglitazone, doxycycline, simvastatin) on MMP-9 and peroxisome proliferator-activated receptor (PPAR)-γ expression in AAA-MSCs.

METHODS

Aneurysmal aortic wall segments were taken from AAA patients after the open surgical treatment. MSCs were isolated from AAA (n = 20) tissues through enzymatic digestion. AAA-MSCs were exposed to different doses of pioglitazone (5-10-25 μM), doxycycline (10-25 μM), and simvastatin (10 μM) for 24 h. The effect of each drug was evaluated in terms of cell survival, by crystal violet stain. MMP-9 and PPAR-γ mRNA were analyzed using real-time PCR.

RESULTS

AAA-MSCs were not affected by the exposure to the selected drugs, as shown by the analysis of cell viability. Interestingly, MMP-9 mRNA resulted significantly decreased after each treatment, recording a downregulation of 50% in presence of pioglitazone, 90% with doxycycline, and 40% with exposed to simvastatin, in comparison to untreated cells. We further analyzed the expression of PPAR-γ, target of pioglitazone, observing an upregulation in exposed AAA-MSCs to controls.

CONCLUSIONS

Our data support the potential therapeutic effect of pioglitazone, doxycycline, and simvastatin on AAA by reducing the MMP-9 expression in a patient-specific model (AAA-MSCs). In addition, pioglitazone drives the increase of PPAR-G, another promising target for AAA therapy. Further studies are necessary to elucidate the mechanism driving this inhibitory pathway, which can reduces the mortality risk associated with AAA rupture.

Toll-Like Receptor 4 and Heat-Shock Protein 70: Is it a New Target Pathway for Diabetic Vasculopathies?

Diabetes is one of the most concerning diseases in modern times. Despite considerable advances in therapeutic management, the prevalence of diabetes and its contribution to death and disability continue to be a major health problem. Diabetic vasculopathies are the leading cause of mortality and morbidity in diabetic patients. Its pathophysiology includes oxidative stress, advanced glycation end products, and a low-grade inflammatory state. Lately, actions of the innate immune system via Toll-like receptors (TLRs) have been suggested as a new insight in this field. TLRs are pattern recognition receptors activated by highly conserved structural motifs of exogenous or endogenous ligands. Heat-shock proteins (HSPs), normally known for their ability to protect cells during stressful conditions, when released from injured cells bind to TLR4 and trigger the release of pro-inflammatory cytokines in a MyD88-dependent pathway. This pathway had been investigated in pancreatic beta cells and skeletal muscle, but it has not yet been explored in the vascular system and deserves investigation. In this work, the interplay between TLR4 and HSP70 in the vasculature during diabetes is reviewed and discussed. The current literature and preliminary results from our laboratory led us to hypothesize that hyperglycemia-associated HSP70 plays an important role in the pathophysiology of diabetic vasculopathies via the TLR4 pathway and might be a new target for therapeutic intervention.

A novel macrophage-mediated biomimetic delivery system with NIR-triggered release for prostate cancer therapy

Background

Macrophages with tumor-tropic migratory properties can serve as a cellular carrier to enhance the efficacy of anti neoplastic agents. However, limited drug loading (DL) and insufficient drug release at the tumor site remain the main obstacles in developing macrophage-based delivery systems. In this study, we constructed a biomimetic delivery system (BDS) by loading doxorubicin (DOX)-loaded reduced graphene oxide (rGO) into a mouse macrophage-like cell line (RAW264.7), hoping that the newly constructed BDS could perfectly combine the tumor-tropic ability of macrophages and the photothermal property of rGO.

Results

At the same DOX concentration, the macrophages could absorb more DOX/PEG-BPEI-rGO than free DOX. The tumor-tropic capacity of RAW264.7 cells towards RM-1 mouse prostate cancer cells did not undergo significant change after drug loading in vitro and in vivo. PEG-BPEI-rGO encapsulated in the macrophages could effectively convert the absorbed near-infrared light into heat energy, causing rapid release of DOX. The BDS showed excellent anti-tumor efficacy in vivo.

Conclusions

The BDS that we developed in this study had the following characteristic features: active targeting of tumor cells, stimuli-release triggered by near-infrared laser (NIR), and effective combination of chemotherapy and photothermotherapy. Using the photothermal effect produced by PEG-BPEI-rGO and DOX released from the macrophages upon NIR irradiation, MAs-DOX/PEG-BPEI-rGO exhibited a significant inhibitory effect on tumor growth.

PPARG2 Pro12Ala and TNFα -308G>A Polymorphisms Are Not Associated with Heart Failure Development in Patients with Ischemic Heart Disease after Coronary Artery Bypass Grafting

TNFα and PPARγ are important modulators of metabolism, inflammation, and atherosclerosis. Coronary artery disease is the leading cause of heart failure (HF). The aim of the study was to assess whether polymorphisms of the TNFα (-308G>A) and PPARG2 (Pro12Ala) genes are associated with the risk of developing HF by patients with ischemic heart disease. Methods. 122 patients without HF (aged 63 ± 8.8 years, 85% males) with confirmed coronary artery disease qualified for coronary bypass grafting were enrolled in the study. After the procedure, they were screened for cardiac parameters. Those with elevated NT-proBNP or diminished left ventricular ejection fraction during follow-up were assigned to the HF group (n=78), and the remaining ones to the non-HF group (n=44). The TNFα -308G>A and PPARG2 Pro12Ala polymorphisms were detected using the TaqMan method. Results. The distributions of TNFα -308G>A and PPARG2 Pro12Ala did not differ between the HF and non-HF groups (-308G>A: 16% vs. 11.4% of alleles; Pro12Ala: 23.9% vs. 20.5% of alleles, respectively). IL-6 concentration in the plasma of TNFα A-allele carriers at months 1 and 12 after CABG was higher in the HF group compared to the non-HF group (1 month after CABG: 5.3 ± 3.4 vs. 3.1 ± 2.9, p<0.05; 12 months after CABG: 4.2 ± 3,9 vs. 1.4 ± 1.2, p<0.01, respectively). Both polymorphisms were not related to changes in the plasma TNFα concentration or other parameters related to HF. Conclusions. Our study did not reveal any correlation between the PPARG2 Pro12Ala and TNFα -308G>A polymorphisms and development of HF in patients with ischemic heart disease after coronary bypass grafting.

Aucubin inhibited lipid accumulation and oxidative stress via Nrf2/HO-1 and AMPK signalling pathways

Aucubin (AU) is the main active ingredient of Aucuba japonica which has showed many positive effects such as anti‐inflammation and liver protection. Non‐alcoholic fatty liver disease (NAFLD) is the most common cause of chronic liver disease. In this research, we explored the effects of AU on the tyloxapol‐induced NAFLD in mice and apolipoprotein C‐III (apoC‐III) induced‐3T3L1 cells. Tyloxapol (300 mg/kg) was injected to C57BL/6 mice with aucubin. The differentiated 3T3‐L1 cells were treated with or without aucubin after stimulation of apoC‐III (100 μg/mL). In results, aucubin inhibited hyperlipidaemia, oxidative stress and inflammation by influencing the content of total cholesterol (TC), triglyceride (TG), low density lipoprotein (LDL), very low density lipoprotein (VLDL), myeloperoxidase (MPO), superoxide dismutase (SOD), tumour necrosis factor receptor‐α (TNF‐α), interleukin‐1β (IL‐1β), and IL‐6 in blood. AU activated NF‐E2‐related factor 2 (Nrf2), peroxisome proliferator‐activated receptor α (PPARα), PPARγ and hemeoxygenase‐1 (HO‐1) and promoted the phosphorylation of adenosine 5′‐monophosphate‐activated protein kinase (AMPKα), AMPKβ, acetyl‐CoA carboxylase (ACC) and protein kinase B (AKT). In conclusion, AU performed the function of hypolipidaemic by its obvious anti‐inflammation and antioxidant activity, which may become a kind of new drug targeting at NAFLD.

Cholesterol Efflux: Does It Contribute to Aortic Stiffening?

Aortic stiffness during cardiac contraction is defined by the rigidity of the aorta and the elastic resistance to deformation. Recent studies suggest that aortic stiffness may be associated with changes in cholesterol efflux in endothelial cells. This alteration in cholesterol efflux may directly affect endothelial function, extracellular matrix composition, and vascular smooth muscle cell function and behavior. These pathological changes favor an aortic stiffness phenotype. Among all of the proteins participating in the cholesterol efflux process, ATP binding cassette transporter A1 (ABCA1) appears to be the main contributor to arterial stiffness changes in terms of structural and cellular function. ABCA1 is also associated with vascular inflammation mediators implicated in aortic stiffness. The goal of this mini review is to provide a conceptual hypothesis of the recent advancements in the understanding of ABCA1 in cholesterol efflux and its role and association in the development of aortic stiffness, with a particular emphasis on the potential mechanisms and pathways involved.

Effect of Hexadecyl Azelaoyl Phosphatidylcholine on Cardiomyocyte Apoptosis in Myocardial Ischemia-Reperfusion Injury: A Hypothesis

Reperfusion after myocardial ischemia can induce cardiomyocyte death, known as myocardial reperfusion injury. The pathophysiology of the process of reperfusion suggests the confluence multiple pathways. Recent studies have focused on the inflammatory response, which is considered to be the main mechanism during the process of myocardial ischemia-reperfusion injury and can cause cardiomyocyte apoptosis. Peroxisome proliferator-activated receptors gamma activated by endogenous ligands and exogenous ligand can decrease the inflammatory response in cardiomyocytes. Thiazolidinediones are synthetic, high-affinity, selective ligands for peroxisome proliferator-activated receptors gamma, and can inhibit the inflammatory response, decrease myocardial infarct size, and protect cardiac function. However, thiazolidinediones, including rosiglitazone and pioglitazone, can also contribute to adverse cardiovascular events such as congestive heart failure. Therefore, there are some limitations to the use of thiazolidinediones. Most endogenous ligands were of low affinity until hexadecyl azelaoyl phosphatidylcholine was identified as a high-affinity ligand and agonist for peroxisome proliferator-activated receptors gamma. Hexadecyl azelaoyl phosphatidylcholine binds recombinant peroxisome proliferator-activated receptors with an affinity (Kd(app) ≈40 nM) which is equivalent to rosiglitazone. Therefore, hexadecyl azelaoyl phosphatidylcholine is a specific peroxisome proliferator-activated receptors gamma agonist. Given these findings, we hypothesized that the use of hexadecyl azelaoyl phosphatidylcholine can activate the peroxisome proliferator-activated receptors gamma signal pathways and prevent the inflammatory response process of myocardial ischemia-reperfusion injury, with reduced cardiomyocyte apoptosis and death.

A myeloperoxidase precursor, pro-myeloperoxidase, is present in human plasma and elevated in cardiovascular disease patients

Myeloperoxidase (MPO)-derived oxidants have emerged as a key contributor to tissue damage in inflammatory conditions such as cardiovascular disease. Pro-myeloperoxidase (pro-MPO), an enzymatically active precursor of myeloperoxidase (MPO), is known to be secreted from cultured bone marrow and promyelocytic leukemia cells, but evidence for the presence of pro-MPO in circulation is lacking. In the present study, we used a LC-MS/MS in addition to immunoblot analyses to show that pro-MPO is present in human blood plasma. Furthermore, we found that pro-MPO was more frequently detected in plasma from patients with myocardial infarction compared to plasma from control donors. Our study suggests that in addition to mature MPO, circulating pro-MPO may cause oxidative modifications of proteins thereby contributing to cardiovascular disease.

Pharmacological Inhibition of Vanin Activity Attenuates Transplant Vasculopathy in Rat Aortic Allografts

BACKGROUND

Development of transplant vasculopathy is a major cause of graft loss and mortality in solid organ transplant recipients. Previous studies in mice have indicated that vanin-1, a member of the vanin protein family with pantetheinase activity, is possibly involved in neointima formation. Here, we investigated if RR6, a recently developed vanin inhibitor, could attenuate development of transplant vasculopathy.

METHODS

Abdominal allogeneic aorta transplantation from Dark Agouti to Brown Norway rats was performed. Surface neointima was quantified 2 and 4 weeks after transplantation. Systemic vanin activity was measured, and allograft leukocyte infiltration, glutathione-synthesizing capacity, matrix metalloproteinase 9 expression and neointimal smooth muscle cell (SMC) proliferation were assessed by immunohistochemistry. In vitro, the effects of RR6 on SMC proliferation (water-soluble tetrazolium-1 assay) and cytokine-induced apoptosis (flow cytometry) were investigated.

RESULTS

RR6 treatment significantly reduced systemic pantetheinase activity during the 4-week follow-up period. RR6 attenuated neointima formation 4 weeks after transplantation. Neointimal SMC proliferation and medial SMC matrix metalloproteinase 9 expression were not altered by RR6. However, RR6 significantly reduced neointimal macrophage influx that was accompanied by increased GCLC messenger RNA expression. In vitro, RR6 inhibited platelet-derived growth factor-induced SMC proliferation and protected SMCs from TNF-α-induced apoptosis.

CONCLUSIONS

Pharmacological inhibition of vanin activity attenuates development of transplant vasculopathy. This was accompanied by reduced macrophage infiltration and increased glutathione-synthesizing capacity. In vitro, RR6 reduced SMC proliferation and apoptosis that was not confirmed in vivo. Further in-depth studies are warranted to reveal the underlying mechanism(s) of RR6-induced attenuation of transplant vasculopathy in vivo.

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.

The role of various peroxisome proliferator-activated receptors and their ligands in clinical practice

Peroxisome proliferator-activated receptors (PPARs) are ligand-activated transcription factors involved in several physiological processes including modulation of cellular differentiation, development, metabolism of carbohydrates, lipids, proteins, and tumorigenesis. The aim of this review is to examine how different PPAR ligands act, and discuss their use in clinical practice. PPAR ligands have a lot of effects and applications in clinical practice. Some PPAR ligands such as fibrates (PPAR-α ligands) are currently used for the treatment of dyslipidemia, while pioglitazone and rosiglitazone (PPAR-γ ligands) are anti-diabetic and insulin-sensitizing agents. Regarding new generation drugs, acting on both α/γ, β/δ, or α/δ receptors simultaneously, preliminary data on PPAR-α/γ dual agonists revealed a positive effect on lipid profile, blood pressure, atherosclerosis, inflammation, and anti-coagulant effects, while the overexpression of PPAR-β/δ seems to prevent obesity and to decrease lipid storage in cardiac cells. Finally, PPAR-α/δ dual agonist induces resolution of nonalcoholic steatohepatitis without fibrosis worsening.

PPARγ and Its Role in Cardiovascular Diseases

Peroxisome proliferator-activated receptor Gamma (PPARγ), a ligand-activated transcription factor, has a role in various cellular functions as well as glucose homeostasis, lipid metabolism, and prevention of oxidative stress. The activators of PPARγ are already widely used in the treatment of diabetes mellitus. The cardioprotective effect of PPARγ activation has been studied extensively over the years making them potential therapeutic targets in diseases associated with cardiovascular disorders. However, they are also associated with adverse cardiovascular events such as congestive heart failure and myocardial infarction. This review aims to discuss the role of PPARγ in the various cardiovascular diseases and summarize the current knowledge on PPARγ agonists from multiple clinical trials. Finally, we also review the new PPARγ agonists under development as potential therapeutics with reduced or no adverse effects.

Fenretinide inhibits macrophage inflammatory mediators and controls hypertension in spontaneously hypertensive rats via the peroxisome proliferator-activated receptor gamma pathway

Fenretinide is a novel anticancer agent reported to exhibit anti-invasive and antimetastatic activities. It has also been shown to improve obesity and diabetes, although the effects of fenretinide on hypertension are still unknown, and the detailed mechanisms remain unclear. In this study, we have shown that treatment with lipopolysaccharide (LPS) decreased the expression of peroxisome proliferator-activated receptor γ (PPARγ) in RAW264.7 macrophages, and pretreatment with fenretinide reversed the effect of LPS on PPARγ expression. In addition, LPS-induced pro-inflammatory cytokine production, including tumor necrosis factor-α, interleukin 6, and monocyte chemoattractant protein 1 were dose-dependently reversed by fenretinide, and the effects of fenretinide on LPS-induced pro-inflammatory cytokine production were blocked by treatment with PPARγ antagonist. Moreover, fenretinide decreased LPS-induced inducible nitric oxide synthase expression and nitrogen oxide production. These effects were blocked by the pretreatment with PPARγ antagonist in a dose-dependent manner, indicating fenretinide activated PPARγ to exert anti-inflammation activity. In view of the role of inflammation in hypertension and the anti-inflammatory action of fenretinide, we found that administration of fenretinide in spontaneously hypertensive rats significantly decreased blood pressure. Taken together, these results indicate that fenretinide might be a potent antihypertensive agent that works by suppressing inflammation via activating PPARγ.

Novel Role for Matrix Metalloproteinase 9 in Modulation of Cholesterol Metabolism

Background

The development of atherosclerosis is strongly linked to disorders of cholesterol metabolism. Matrix metalloproteinases (MMPs) are dysregulated in patients and animal models with atherosclerosis. Whether systemic MMP activity influences cholesterol metabolism is unknown.

Methods and Results

We examined MMP‐9–deficient (Mmp9^−/−) mice and found them to have abnormal lipid gene transcriptional responses to dietary cholesterol supplementation. As opposed to Mmp9^+/+ (wild‐type) mice, Mmp9^−/− mice failed to decrease the hepatic expression of sterol regulatory element binding protein 2 pathway genes, which control hepatic cholesterol biosynthesis and uptake. Furthermore, Mmp9^−/− mice failed to increase the expression of genes encoding the rate‐limiting enzymes in biliary cholesterol excretion (eg, Cyp7a and Cyp27a). In contrast, MMP‐9 deficiency did not impair intestinal cholesterol absorption, as shown by the ¹⁴C‐cholesterol and ³H‐sitostanol absorption assay. Similar to our earlier study on Mmp2^−/− mice, we observed that Mmp9^−/− mice had elevated plasma secreted phospholipase A₂ activity. Pharmacological inhibition of systemic circulating secreted phospholipase A₂ activity (with varespladib) partially normalized the hepatic transcriptional responses to dietary cholesterol in Mmp9^−/− mice. Functional studies with mice deficient in other MMPs suggested an important role for the MMP system, as a whole, in modulation of cholesterol metabolism.

Conclusions

Our results show that MMP‐9 modulates cholesterol metabolism, at least in part, through a novel MMP‐9–plasma secreted phospholipase A₂ axis that affects the hepatic transcriptional responses to dietary cholesterol. Furthermore, the data suggest that dysregulation of the MMP system can result in metabolic disorder, which could lead to atherosclerosis and coronary heart disease.

Nanomedicine engulfed by macrophages for targeted tumor therapy

Macrophages, exhibiting high intrinsic accumulation and infiltration into tumor tissues, are a novel drug vehicle for directional drug delivery. However, the low drug-loading (DL) capacity and the drug cytotoxicity to the cell vehicle have limited the application of macrophages in tumor therapy. In this study, different drugs involving small molecular and nanoparticle drugs were loaded into intrinsic macrophages to find a better way to overcome these limitations. Their DL capacity and cytotoxicity to the macrophages were first compared. Furthermore, their phagocytic ratio, dynamic distributions, and tumoricidal effects were also investigated. Results indicated that more lipid-soluble molecules and DL particles can be phagocytized by macrophages than hydrophilic ones. In addition, the N-succinyl-N'-octyl chitosan (SOC) DL particles showed low cytotoxicity to the macrophage itself, while the dynamic biodistribution of macrophages engulfed with different particles/small molecules showed similar profiles, mainly excreted from liver to intestine pathway. Furthermore, macrophages loaded with SOC-paclitaxel (PTX) particles exhibited greater therapeutic efficacies than those of macrophages directly carrying small molecular drugs such as doxorubicin and PTX. Interestingly, macrophages displayed stronger targeting ability to the tumor site hypersecreting chemokine in immunocompetent mice in comparison to the tumor site secreting low levels of chemokine in immunodeficiency mice. Finally, results demonstrated that macrophages carrying SOC-PTX are a promising pharmaceutical preparation for tumor-targeted therapy.

PPAR Ligands Function as Suppressors That Target Biological Actions of HMGB1

High mobility group box 1 (HMGB1), which has become one of the most intriguing molecules in inflammatory disorders and cancers and with which ligand-activated peroxisome proliferator-activated receptors (PPARs) are highly associated, is considered as a therapeutic target. Of particular interest is the fact that certain PPAR ligands have demonstrated their potent anti-inflammatory activities and potential anticancer effects. In this review article we summarize recent experimental evidence that PPAR ligands function as suppressors that target biological actions of HMGB1, including intracellular expression, receptor signaling cascades, and extracellular secretion of HMGB1 in cell lines and/or animal models. We also propose the possible mechanisms underlying PPAR involvement in inflammatory disorders and discuss the future therapeutic value of PPAR ligands targeting HMGB1 molecule for cancer prevention and treatment.

Association between peroxisome proliferator-activated receptor-alpha, delta, and gamma polymorphisms and risk of coronary heart disease: A case-control study and meta-analysis

OBJECTIVES

Risk of coronary heart disease (CHD) has been suggested to be associated with polymorphisms of peroxisome proliferator-activated receptors (PPARs), while the results were controversial. We aimed to systematically assess the association between PPAR polymorphisms and CHD risk.

METHODS

A case-control study with 446 subjects was conducted to evaluate the association between CHD risk and C161T polymorphism, which was of our special interest as this polymorphism showed different effects on risks of CHD and acute coronary syndrome (ACS). Meta-analyses were conducted to assess all PPAR polymorphisms. Either a fixed- or a random-effects model was adopted to estimate overall odds ratios (ORs).

RESULTS

In the case-control study, T allele carriers of C161T polymorphism were not significantly associated with CHD risk (Odds ratio (OR) = 0.74, 95% confidence interval (CI) 0.47-1.15, P = 0.19), while T allele carriers showed higher risk of ACS (OR = 1.63, 95% CI 1.00-2.65, P = 0.048). The meta-analysis indicated that compared with CC homozygous, T allele carriers had lower CHD risk (OR = 0.69, 95% CI 0.59-0.82, P < 0.001) but higher ACS risk (OR = 1.43, 95% CI 1.09-1.87, P = 0.010). Three other polymorphisms were also found to be significantly associated with CHD risk under dominant model: PPAR-alpha intron 7G/C polymorphism (CC+GC vs GG, OR 1.42, 95% CI 1.13-1.78, P = 0.003), L162V polymorphism (VV+LV vs LL, OR 0.74, 95% CI 0.56-0.97, P = 0.031), and PPAR-delta +294T/C polymorphism (CC+TC vs TT, OR 1.51, 95% CI 1.12-2.05, P = 0.007).

CONCLUSIONS

The results suggested that PPAR-alpha intron 7G/C and L162V, PPAR-delta +294T/C and PPAR-gamma C161T polymorphisms could affect CHD susceptibility, and C161T polymorphism might have different effects on CHD and ACS.

Review: The metabolic syndrome as an endocrine disease: is there an effective pharmacotherapeutic strategy optimally targeting the pathogenesis?

The metabolic syndrome (MetS) represents a combination of cardiovascular risk determinants such as obesity, insulin resistance and lipid abnormalities such as hypertriglyceridemia, increased free fatty acids, low high-density-cholesterol and hypertension. As a multiple component condition it imparts a doubling of relative risk for atherosclerotic cardiovascular disease (ASCVD). It is currently controversial which component of the syndrome carries what weight. There is even a considerable debate whether the risk for ASCVD is greater in patients diagnosed with MetS than that by the individual risk factors. At present, no unifying pathogenetic mechanism can explain the metabolic syndrome and there is no unique treatment for it. This review summarizes and critically reviews the currently available clinical and scientific evidence for the concept that the MetS is causally an endocrine disease and discusses pharmacotherapeutic strategies targeting the pathogenesis rather than single symptoms of the cluster.

Hyperhomocysteinemic Diabetic Cardiomyopathy: Oxidative Stress, Remodeling, and Endothelial-Myocyte Uncoupling

Accumulation of oxidized-matrix (fibrosis) between the endothelium (the endothelial cells embedded among the myocytes) and cardiomyocytes is a hallmark of diabetes mellitus and causes diastolic impairment. In diabetes mellitus, elevated levels of homocysteine activate matrix metalloproteinase and disconnect the endothelium from myocytes. Extracellular matrix functionally links the endothelium to the cardiomyocyte and is important for their synchronization. However, in diabetes mellitus, a disconnection is caused by activated metalloproteinase, with subsequent accumulation of oxidized matrix between the endothelium and myocyte. This contributes to endothelial-myocyte uncoupling and leads to impaired diastolic relaxation of the heart in diabetes mellitus. Elevated levels of homocysteine in diabetes are attributed to impaired homocysteine metabolism by glucose and insulin and decreased renal clearance. Homocysteine induces oxidative stress and is inversely related to the expression of peroxisome proliferators activated receptor (PPAR). Several lines of evidence suggest that ablation of the matrix metalloproteinase (MMP-9) gene ameliorates the endothelial-myocyte uncoupling in diabetes mellitus. Homocysteine competes for, and decreases the PPARγ activity. In diabetes mellitus, endothelial-myocyte uncoupling is associated with matrix metalloproteinase activation and decreased PPARγ activity. The purpose of this review is to discuss the role of endothelial-myocyte uncoupling in diabetes mellitus and increased levels of homocysteine, causing activation of latent metalloproteinases, decreased levels of thioredoxin and peroxiredoxin, and cardiac tissue inhibitor of metalloproteinase (CIMP) in response to antagonizing PPARγ.

Multidimensional Contribution of Matrix Metalloproteinases to Atherosclerotic Plaque Vulnerability: Multiple Mechanisms of Inhibition to Promote Stability

The prevalence of atherosclerotic disease continues to increase, and despite significant reductions in major cardiovascular events with current medical interventions, an additional therapeutic window exists. Atherosclerotic plaque growth is a complex integration of cholesterol penetration, inflammatory cell infiltration, vascular smooth muscle cell (VSMC) migration, and neovascular invasion. A family of matrix-degrading proteases, the matrix metalloproteinases (MMPs), contributes to all phases of vascular remodeling. The contribution of specific MMPs to endothelial cell integrity and VSMC migration in atherosclerotic lesion initiation and progression has been confirmed by the increased expression of these proteases in plasma and plaque specimens. Endogenous blockade of MMPs by the tissue inhibitors of metalloproteinases (TIMPs) may attenuate proteolysis in some regions, but the progression of matrix degeneration suggests that MMPs predominate in atherosclerotic plaque, precipitating vulnerability. Plaque neovascularization also contributes to instability and, coupling the known role of MMPs in angiogenesis to that of atherosclerotic plaque growth, interest in targeting MMPs to facilitate plaque stabilization continues to accumulate. This article aims to review the contributions of MMPs and TIMPs to atherosclerotic plaque expansion, neovascularization, and rupture vulnerability with an interest in promoting targeted therapies to improve plaque stabilization and decrease the risk of major cardiovascular events.

Short-term treatment with a 2-carba analog of cyclic phosphatidic acid induces lowering of plasma cholesterol levels in ApoE-deficient mice

Plasma cholesterol levels are associated with an increased risk of developing atherosclerosis. An elevated low-density lipoprotein cholesterol (LDL-C) level is a hallmark of hypercholesterolemia in metabolic syndrome. Our previous study suggested that when acetylated LDL (AC-LDL) was co-applied with a PPARγ agonist, rosiglitazone (ROSI), many oil red O-positive macrophages could be observed. However, addition of cyclic phosphatidic acid (cPA) to ROSI-stimulated macrophages completely abolished oil red O-stained cells, indicating that cPA inhibits PPARγ-regulated AC-LDL uptake. This study aimed to determine whether metabolically stabilized cPA, in the form of a carba-derivative of cPA (2ccPA), could reduce plasma cholesterol levels and affect the expression of genes related to atherosclerosis in apolipoprotein E-knockout (apoE(-/-)) mice. 2ccPA reduced LDL-C levels in these mice (n = 3) from 460 to 330 mg/ml, from 420 to 350 mg/ml, and 420 to 281 mg/ml under a western-type diet. 2ccPA also reduced expression of lipid metabolism-related genes, cytokines, and chemokines in ApoE-deficient mice on a high-fat diet. Taken together, these results suggest that 2ccPA governs anti-atherogenic activities in the carotid arteries of apoE-deficient mice.

Gestational diabetes mellitus is associated with increased leukocyte peroxisome proliferator-activated receptor γ expression

INTRODUCTION

Peroxisome proliferator-activated receptor γ (PPARγ) is a ligand-activated transcription factor of the nuclear receptor superfamily that is involved in lipid and carbohydrate metabolism as well as inflammation; thereby it participates in metabolic diseases including diabetes. Although PPARγ expression has been observed in different tissues of diabetic patients, its level in leukocytes from subjects affected by gestational diabetes mellitus (GDM) has not yet been reported. This study aimed to investigate leukocyte PPARG expression in GDM patients at 24-33 weeks of gestation and, in turn, to correlate these alterations with anthropometric and metabolic parameters of patients.

MATERIAL AND METHODS

Leukocytes were isolated from the blood of normal glucose tolerant (NGT; n = 34) and GDM (n = 77) pregnant women between 24 and 33 weeks of gestation. Leukocyte PPARG mRNA expression was determined by semi-quantitative polymerase chain reaction. Univariate correlation analysis was performed to investigate associations between PPARG expression and clinical characteristics of patients.

RESULTS

Leukocyte PPARG mRNA level was significantly higher in GDM than NGT women (p < 0.05). In the whole study group, PPARG expression positively correlated with plasma glucose concentrations at 1 h (r = 0.222, p = 0.049) and 2 h (r = 0.315, p = 0.020) of 75 g oral glucose tolerance test (OGTT), and negatively correlated with plasma HDL cholesterol concentration (r = -0.351, p = 0.010).

CONCLUSIONS

The correlation between leukocyte PPARG overexpression and hyperglycaemia suggests that PPARG mRNA expression in these cells might be up-regulated in high-glucose conditions in GDM patients at 24-33 weeks of gestation.

The Interaction between Fluid Wall Shear Stress and Solid Circumferential Strain Affects Endothelial Gene Expression

Endothelial cells lining the walls of blood vessels are exposed simultaneously to wall shear stress (WSS) and circumferential stress (CS) that can be characterized by the temporal phase angle between WSS and CS (stress phase angle - SPA). Regions of the circulation with highly asynchronous hemodynamics (SPA close to -180°) such as coronary arteries are associated with the development of pathological conditions such as atherosclerosis and intimal hyperplasia whereas more synchronous regions (SPA closer to 0°) are spared of disease. The present study evaluates endothelial cell gene expression of 42 atherosclerosis-related genes under asynchronous hemodynamics (SPA=-180 °) and synchronous hemodynamics (SPA=0 °). This study used a novel bioreactor to investigate the cellular response of bovine aortic endothelial cells (BAECS) exposed to a combination of pulsatile WSS and CS at SPA=0 or SPA=-180. Using a PCR array of 42 genes, we determined that BAECS exposed to non-reversing sinusoidal WSS (10±10 dyne/cm2) and CS (4 ± 4%) over a 7 hour testing period displayed 17 genes that were up regulated by SPA = -180 °, most of them pro-atherogenic, including NFκB and other NFκB target genes. The up regulation of NFκB p50/p105 and p65 by SPA =-180° was confirmed by Western blots and immunofluorescence staining demonstrating the nuclear translocation of NFκB p50/p105 and p65. These data suggest that asynchronous hemodynamics (SPA=-180 °) can elicit proatherogenic responses in endothelial cells compared to synchronous hemodynamics without shear stress reversal, indicating that SPA may be an important parameter characterizing arterial susceptibility to disease.

Pro-inflammatory effect of fibrinogen on vascular smooth muscle cells by regulating the expression of PPARα, PPARγ and MMP-9

Atherosclerosis is a chronic inflammatory disease in the vessel. As one of the inflammatory markers, fibrinogen has been indicated in formation and progression of atherosclerosis. However, it is completely unclear whether fibrinogen produces a pro-inflammatory effect on vascular smooth muscle cells (VSMCs). The purpose of the present study was to observe the effect of fibrinogen on the expression of peroxisome proliferator-activated receptors-α (PPARα), PPARγ and matrix metalloproteinase-9 (MMP-9) in VSMCs. Rat VSMCs were cultured and fibrinogen was used as a stimulant for PPARα, PPARγ and MMP-9 expression. mRNA expression of PPARα, PPARγ and MMP-9 was identified with the reverse transcription polymerase chain reaction. Protein production of PPARα and PPARγ was examined by western blot analysis and the MMP-9 level in the supernatant of VSMCs was measured with the enzyme-linked immunosorbent assay. The results showed that fibrinogen downregulated mRNA and protein expression of PPARα and PPARγ, and upregulated mRNA and protein generation of MMP-9 in VSMCs in time- and concentration-dependent manners. The maximal inhibition of protein expression of PPARα and PPARγ was 71.8 and 79.9%, respectively. The maximal release of MMP-9 was 4 times over the control. The results suggest that fibrinogen exerts a pro-inflammatory effect on VSMCs through inhibiting the expression of anti-inflammatory cytokine PPARα and PPARγ and stimulating the production of pro-inflammatory cytokine MMP-9. The findings provide new evidence for the pro-inflammatory and pro-atherosclerotic effects of fibrinogen.

Drug repositioning for gynecologic tumors: a new therapeutic strategy for cancer

The goals of drug repositioning are to find a new pharmacological effect of a drug for which human safety and pharmacokinetics are established and to expand the therapeutic range of the drug to another disease. Such drug discovery can be performed at low cost and in the short term based on the results of previous clinical trials. New drugs for gynecologic tumors may be found by drug repositioning. For example, PPAR ligands may be effective against ovarian cancer, since PPAR activation eliminates COX-2 expression, arrests the cell cycle, and induces apoptosis. Metformin, an antidiabetic drug, is effective for endometrial cancer through inhibition of the PI3K-Akt-mTOR pathway by activating LKB1-AMPK and reduction of insulin and insulin-like growth factor-1 due to AMPK activation. COX-2 inhibitors for cervical cancer may also be examples of drug repositioning. PGE2 is induced in the arachidonate cascade by COX-2. PGE2 maintains high expression of COX-2 and induces angiogenic factors including VEGF and bFGF, causing carcinogenesis. COX-2 inhibitors suppress these actions and inhibit carcinogenesis. Combination therapy using drugs found by drug repositioning and current anticancer drugs may increase efficacy and reduce adverse drug reactions. Thus, drug repositioning may become a key approach for gynecologic cancer in drug discovery.

Processing of CXCL12 impedes the recruitment of endothelial progenitor cells in diabetic wound healing

High blood sugar levels result in defective wound healing processes in diabetic patients. Endothelial progenitor cells (EPCs) play an important role in vasculogenesis, and thereby contribute to reconstitution of the microcirculation and healing. This study aimed to determine the possible mechanism by which the numbers of circulating EPCs are regulated in response to tissue wounding. In the streptozotocin-induced diabetic mouse model, we found that phagocytes activated by local inflammatory cytokines in the wound interfere with the mobilization and recruitment of EPCs to the lesion area. Specifically, the activated macrophages inactivate CXCL12, the major chemokine for EPC recruitment, via matrix metalloproteinases (MMPs), and thereby prevent local chemotaxis and subsequent homing of EPCs to the wound. The wound healing process is delayed by local administration of inflammatory cytokines, and its rate is increased by MMP inhibitors. This study indicates that local inhibition of MMPs is beneficial for regeneration of damaged vessels, and may explain poor wound healing in diabetic patients, thus demonstrating its potential utility as a local treatment therapy to promote diabetic wound healing.

Thiazolidinedione-independent activation of peroxisome proliferator-activated receptor γ is a potential target for diabetic macrovascular complications

Macrovascular complications are responsible for the high morbidity and mortality in patients with diabetes. Peroxisome proliferator‐activated receptor γ (PPARγ) plays a central role in the process of adipocyte differentiation and insulin sensitization, and also possesses anti‐atherogenic effects. Recently, some statins, angiotensin II type 1 receptor blockers and calcium channel blockers have been reported to activate PPARγ. However, the impact of PPARγ activation on diabetic macrovascular complications is not fully understood. It has been reported that the activation of PPARγ by thiazolidinediones induces anti‐atherogenic effects in vascular cells, including monocytes/macrophages, endothelial cells and smooth muscle cells, in atherosclerotic animal models and in clinical studies. We have reported that hydroxymethylglutaryl coenzyme A reductase inhibitors (statins), which are used for treatment of hypercholesterolemia, activate PPARγ and mediate anti‐atherogenic effects through PPARγ activation in macrophages. Also, telmisartan, an angiotensin type I receptor blocker, has been reported to have anti‐atherogenic effects through PPARγ activation. Furthermore, we have reported that nifedipine, a dihydropyridine calcium channel blocker, can activate PPARγ, thereby mediating anti‐atherogenic effects in macrophages. Therefore, statin therapy and part of anti‐hypertensive therapy might produce beneficial effects through PPARγ activation in hypercholesterolemic and/or hypertensive patients with diabetes, and PPARγ might be a therapeutic target for diabetic macrovascular complications. In the present review, we focus on the anti‐atherogenic effects of PPARγ and suggest potential therapeutic approaches to prevent diabetic macrovascular complications. (J Diabetes Invest, doi: 10.1111/j.2040‐1124.2011.00182.x, 2012)

Effect of the PPARγ C161T gene variant on serum lipids in ischemic stroke patients with and without type 2 diabetes mellitus

Peroxisome proliferator-activated receptor γ (PPARγ) is a ligand-activated transcription factor involved in the regulation of lipid metabolism, diabetes, obesity, atherogenesis and inflammation. PPARγ genetic variation has been associated with metabolic and cardiovascular diseases. The aim of this study was to explore, for the first time, the relationship between PPARγ C161T polymorphism and the risk of ischemic stroke (IS) among patients with type 2 diabetes mellitus (T2DM). A total of 196 patients with IS (117 diabetics and 79 nondiabetics) and 192 controls were recruited to enroll in this study. PPARγ C161T genotyping was performed by PCR-RFLP technique. The 161T allele as compared with C allele was found to be higher in controls than in IS patients (with or without T2DM). After adjusting for multiple risk factors, the T allele carriers had significantly reduced IS risk (OR=0.575, 95% CI 0.348-0.951, p=0.030) compared to the CC homozygotes which increased significantly the risk in IS patients with T2DM (OR=1.85, 95% CI 1.23-2.62). Moreover, the triglycerides (TG) and ApoB levels in CC homozygote carriers were significantly higher than those in T allele carriers. These results indicate that the C161T of PPARγ may reduce the risk of IS by modulation of adipose metabolism especially TG and ApoB in IS patients with T2DM.

Effects of vitamin E on peroxisome proliferator-activated receptor γ and nuclear factor-erythroid 2-related factor 2 in hypercholesterolemia-induced atherosclerosis

Atherosclerosis and associated cardiovascular complications such as stroke and myocardial infarction are major causes of morbidity and mortality. We have previously reported a significant increase in mRNA levels of the scavenger receptor CD36 in aortae of cholesterol-fed rabbits and shown that vitamin E treatment attenuated increased CD36 mRNA expression. In the present study, we further investigated the redox signaling pathways associated with protection against atherogenesis induced by high dietary cholesterol and correlated these with CD36 expression and the effects of vitamin E supplementation in a rabbit model. Male albino rabbits were assigned to either a control group fed with a low vitamin E diet alone or a test group fed with a low vitamin E diet containing 2% cholesterol in the absence or presence of daily intramuscular injections of vitamin E (50mg/kg). To elucidate the mechanisms by which vitamin E supplementation alters the effects of hypercholesterolemia in rabbit aortae, we measured peroxisome proliferator-activated receptor γ (PPARγ), ATP-binding cassette transporter A1 (ABCA1), and matrix metalloproteinase-1 (MMP-1) mRNA levels by quantitative RT-PCR and the expression of MMP-1, nuclear factor-erythroid 2-related factor 2 (Nrf2), and glutathione S-transferase α (GSTα) protein by immunoblotting. The increased MMP-1 and decreased GSTα expression observed suggests that a cholesterol-rich diet contributes to the development of atherosclerosis, whereas vitamin E supplementation affords protection by decreasing MMP-1 and increasing PPARγ, GSTα, and ABCA1 levels in aortae of rabbits fed a cholesterol-rich diet. Notably, protein expression of Nrf2, the antioxidant transcription factor, was increased in both the cholesterol-fed and the vitamin E-supplemented groups. Although Nrf2 activation can promote CD36-mediated cholesterol uptake by macrophages, the increased induction of Nrf2-mediated antioxidant genes is likely to contribute to decreased lesion progression. Thus, our study demonstrates that Nrf2 can mediate both pro- and antiatherosclerotic effects.

Distribution and genotype frequency of the C1431T and pro12ala polymorphisms of the peroxisome proliferator activator receptor gamma gene in an Iranian population

BACKGROUND

Peroxisome proliferator activator receptor gamma (PPARγ) is a nuclear transcription factor regulating multiple genes involved in cell growth, differentiation, carbohydrate and lipid metabolism and energy production. Several genetic variations in the PPARγ gene have been identified to be associated with diabetes, obesity, dyslipidemia, insulin resistance, metabolic syndrome and coronary artery disease. The present study was designed to explore the distribution of two common single nucleotide polymorphisms of the PPARγ gene (C1431T and Pro12Ala) in an Iranian population.

MATERIALS AND METHODS

Genotype frequencies for these two polymorphisms were compared for 160 healthy Iranian individuals with reports from other populations. The Genotyping was performed using real-time polymerase chain reaction.

RESULTS

The genotype distribution of the C1431T PPARγ polymorphism was 0.869 for the CC genotype, 0.119 for the CT genotype and 0.013 for uncommon TT genotype. Allelic frequencies were 0.93 for C and 0.07 for T allele respectively. For the Pro12Ala polymorphism of PPARγ gene, genotypic distributions and allelic frequencies were, 0.813 for CC, 0.181 for CG and 0.06 for GG and 0.903 for C and 0.097 for G respectively. Allelic and genotypic frequencies for both polymorphisms of PPARγ gene were in Hardy-Weinberg equilibrium.

CONCLUSIONS

Iran is a country with an ethnically diverse population and a comparison of allelic and genotypic frequencies of PPARγ C1431T and Pro12Ala polymorphisms between our population and others showed significant differences.

The impact of bubbles on measurement of drug release from echogenic liposomes

Echogenic liposomes (ELIP) encapsulate gas bubbles and drugs within lipid vesicles, but the mechanisms of ultrasound-mediated drug release from ELIP are not well understood. The effect of cavitation activity on drug release from ELIP was investigated in flowing solutions using two fluorescent molecules: a lipophilic drug (rosiglitazone) and a hydrophilic drug substitute (calcein). ELIP samples were exposed to pulsed Doppler ultrasound from a clinical diagnostic ultrasound scanner at pressures above and below the inertial and stable cavitation thresholds. Control samples were exposed to a surfactant, Triton X-100 (positive control), or to flow alone (negative control). Fluorescence techniques were used to detect release. Encapsulated microbubbles reduced the measured fluorescence intensity and this effect should be considered when assessing drug release from ELIP. The origin of this effect is not specific to ELIP. Release of rosiglitazone or calcein compared to the negative control was only observed with detergent treatment, but not with ultrasound exposure, despite the presence of stable and inertial cavitation activity. Release of rosiglitazone or calcein from ELIP exposed to diagnostic ultrasound was not observed, even in the presence of cavitation activity. Ultrasound-mediated drug delivery strategies with ELIP will thus rely on passage of the drug-loaded liposomes to target tissues.

Combination of peroxisome proliferator-activated receptor α/γ agonists may benefit type 2 diabetes patients with coronary artery disease through inhibition of inflammatory cytokine secretion

Patients with type 2 diabetes mellitus (T2DM) have a higher risk of cardiovascular disease (CVD). Peroxisome proliferator-activated receptors (PPARs) play an important role in the regulation of energy homeostasis. Therefore, we aimed to observe the effects of combined PPARα/γ agonists on T2DM patients with coronary artery disease (CAD). Patients were randomly divided into a rosiglitazone (RSG) group (n=20), a bezafibrate (BEZ) group (n=20), a combination of RSG and BEZ group (n=20) and a control group (n=20). Plasma C-reactive protein (CRP) and monocyte chemoattractant protein-1 (MCP-1) were measured by enzyme-linked immunosorbent assay before and 12 weeks after treatment. Fasting blood glucose (FBG), fasting insulin, insulin resistance index (IRI), hemoglobin A1c (HbA1c), lipid levels and body mass index were also investigated. At the end of the treatment, FBG, insulin, IRI, HbA1c and triglyceride levels decreased and the level of high-density lipoprotein cholesterol increased in the RSG, BEZ and combination groups. A decrease in low-density lipoprotein cholesterol was only observed in the combination group. Although the total cholesterol levels in all groups decreased, no significant difference was noted. The levels of CRP and MCP-1 were reduced in patients in the RSG, BEZ and combination groups. In addition, RSG, BEZ and the combination of RSG and BEZ also inhibited MCP-1 secretion. The combination of RSG and BEZ was more efficient than RSG or BEZ alone in downregulating cytokines. In conclusion, our results suggest that a combination of RSG and BEZ may be more efficient than RSG or BEZ alone in the treatment of T2DM patients with CAD.