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Background: Dipeptidyl peptidase-4 (DPP-4) inhibitors have various cellular effects that are associated with vascular protection. Here, we examined whether teneligliptin alters the pro-inflammatory phenotype of perivascular adipose tissue (PVAT) and inhibits atherogenesis., Methods and Results: Teneligliptin (60mg/kg/day) was administered orally to apolipoprotein-E-deficient (ApoE -/- ) mice for 20weeks. Teneligliptin significantly inhibited the development of atherosclerosis in the aortic arch compared with vehicle (P<0.05), without alteration of blood glucose level or blood pressure. Histological analyses demonstrated that teneligliptin decreased lipid deposition and MCP-1 expression (P<0.05, respectively), and tended to decrease macrophage accumulation in atherosclerotic plaques. The results of quantitative RT-PCR analysis demonstrated that teneligliptin reduced the expression of inflammatory molecules such as TNF-α and MCP-1 in the abdominal aorta. Furthermore, teneligliptin reduced the expression of a macrophage marker and Nox-4, a major NADPH oxidase subunit in adipocytes, in PVAT around the aortic arch. Administration of teneligliptin for 8weeks ameliorated endothelium-dependent vasodilation and reduced oxidative stress as determined by urinary 8-OHdG excretion (P<0.05) compared with vehicle. In vitro experiments demonstrated that exendin-4 (Ex-4), a GLP-1 analog, decreased the expression of inflammatory molecules in RAW264.7 cells. Also, Ex-4 decreased Nox4 expression in 3T3-L1 adipocytes., Conclusion: Teneligliptin inhibited atherogenesis with attenuation of the inflammatory phenotype in PVAT. A GLP-1 analog suppressed pro-inflammatory activation of macrophages and adipocytes. Suppression of the pro-inflammatory phenotype of PVAT might contribute, at least partially, to the cardioprotective effects of teneligliptin., (Copyright © 2017 Elsevier Inc. All rights reserved.)

Obesity stimulates chronic inflammation in adipose tissue, which is associated with insulin resistance, although the underlying mechanism remains largely unknown. Here we showed that obesity-related adipocyte degeneration causes release of cell-free DNA (cfDNA), which promotes macrophage accumulation in adipose tissue via Toll-like receptor 9 (TLR9), originally known as a sensor of exogenous DNA fragments. Fat-fed obese wild-type mice showed increased release of cfDNA, as determined by the concentrations of single-stranded DNA (ssDNA) and double-stranded DNA (dsDNA) in plasma. cfDNA released from degenerated adipocytes promoted monocyte chemoattractant protein-1 (MCP-1) expression in wild-type macrophages, but not in TLR9-deficient (Tlr9 (-/-) ) macrophages. Fat-fed Tlr9 (-/-) mice demonstrated reduced macrophage accumulation and inflammation in adipose tissue and better insulin sensitivity compared with wild-type mice, whereas bone marrow reconstitution with wild-type bone marrow restored the attenuation of insulin resistance observed in fat-fed Tlr9 (-/-) mice. Administration of a TLR9 inhibitory oligonucleotide to fat-fed wild-type mice reduced the accumulation of macrophages in adipose tissue and improved insulin resistance. Furthermore, in humans, plasma ssDNA level was significantly higher in patients with computed tomography-determined visceral obesity and was associated with homeostasis model assessment of insulin resistance (HOMA-IR), which is the index of insulin resistance. Our study may provide a novel mechanism for the development of sterile inflammation in adipose tissue and a potential therapeutic target for insulin resistance.

Objective: The impact of epicardial adipose tissue (EAT) over abdominal or overall adiposity on coronary artery disease (CAD) is currently unknown. We compared the association among EAT volume (EATV), cytokine/adipocytokine profiles in EAT and subcutaneous fat, and atherogenic CAD., Approach and Results: Paired samples were obtained from EAT and subcutaneous adipose tissue during elective cardiac surgery for CAD (n=50) or non-CAD (n=50). EATV was the sum of cross-sectional EAT areas, and visceral and subcutaneous fat areas were determined at the umbilicus level on computed tomography scans. CD68(+), CD11c(+), and CD206(+) cells were counted using immunohistochemical staining. Cytokine/adipocytokine expression was evaluated using quantitative real-time polymerase chain reaction. Multivariate analysis indicated that male sex, age, diabetes mellitus, high triglycerides, and low high-density lipoprotein cholesterol, and EATV index (EATV/body surface area, cm(3)/m(2)) were significant CAD predictors (corrected R(2)=0.401; P<0.001); visceral fat area, hypertension, smoking, low-density lipoprotein cholesterol (140 mg/dL [3.63 mmol/L]) or statin use were not predictors. The EATV index positively correlated with the CD68(+) and CD11c(+) cell numbers and nucleotide-binding domain, leucine-rich-containing family, pyrin domain-containing-3 (NLRP3), interleukin-1β, and interleukin-1R expression; and negatively correlated with adiponectin expression in EAT. A multivariate analysis model, including CD68(+) cells and interleukin-1β, and adiponectin expression in EAT strongly predicted CAD (corrected R(2)=0.756; P<0.001)., Conclusions: EATV and macrophage and cytokine/adipocytokine signals in EAT strongly correlated with CAD. Our findings suggest that EATV and adipocytokine imbalance are strongly linked to human coronary atherosclerosis.

Much attention is currently focused on the role of perivascular adipose tissue in development of cardiovascular disease (CVD). Some researchers view it as promoting CVD through secretion of cytokines and growth factors called adipokines, while recent reports reveal that perivascular adipose tissue can exert a protective effect on CVD development. Furthermore, adiponectin, an anti-inflammatory adipokine, reportedly suppresses neointimal hyperplasia after endovascular injury, whereas such vascular remodeling is enhanced by pro-inflammatory adipokines secreted by perivascular adipose, such as tumor necrosis factor-α (TNF-α). These findings suggest that extent of vascular remodeling, a pathological process associated with CVD development, depends on the balance between pro- and anti-inflammatory adipokines secreted from perivascular adipose tissue. We previously demonstrated that angiopoietin-like protein 2 (Angptl2), a pro-inflammatory factor secreted by adipose tissue, promotes adipose tissue inflammation and subsequent systemic insulin resistance in obesity. Here, we examined whether Angptl2 secreted by perivascular adipose tissue contributes to vascular remodeling after endovascular injury in studies of transgenic mice expressing Angptl2 in adipose tissue (aP2-Angptl2 transgenic mice) and Angptl2 knockout mice (Angptl2(-/-) mice). To assess the role of Angptl2 secreted by perivascular adipose tissue on vascular remodeling after endovascular injury, we performed adipose tissue transplantation experiments using these mice. Wild-type mice with perivascular adipose tissue derived from aP2-Angptl2 mice exhibited accelerated neointimal hyperplasia after endovascular injury compared to wild-type mice transplanted with wild-type tissue. Conversely, vascular inflammation and neointimal hyperplasia after endovascular injury were significantly attenuated in wild-type mice transplanted with Angptl2(-/-) mouse-derived perivascular adipose tissue compared to wild-type mice transplanted with wild-type tissue. RT-PCR analysis revealed that mouse Angptl2 expression in perivascular adipose tissue was significantly increased by aging, hypercholesterolemia, and endovascular injury, all risk factors for coronary heart disease (CHD). Immunohistochemical and RT-PCR analysis of tissues from patients with CHD and from non-CHD patients indicated that ANGPTL2 expression in epicardial adipose tissue was unchanged. Interestingly, that analysis also revealed a positive correlation in ANGPTL2 and ADIPONECTIN expression in epicardial adipose tissue of non-CHD patients, a correlation not seen in CHD patients. However, in epicardial adipose tissue from CHD patients, ANGPTL2 expression was positively correlated with that of TNF-α, a correlation was not seen in non-CHD patients. These findings suggest that pro-inflammatory adipokines cooperatively accelerate CHD development and that maintaining a balance between pro- and anti-inflammatory adipokines likely protects non-CHD patients from developing CHD. Overall, our studies demonstrate that perivascular adipose tissue-secreted Angptl2 accelerates vascular inflammation and the subsequent CVD development., (Copyright © 2013 Elsevier Ltd. All rights reserved.)

Background: Growing evidence suggests that epicardial adipose tissue (EAT) may contribute to the development of coronary artery disease (CAD). In this study, we explored gender disparities in EAT volume (EATV) and its impact on coronary atherosclerosis., Methods: The study population consisted of 90 consecutive subjects (age: 63 ± 12 years; men: 47, women: 43) who underwent 256-slice multi-detector computed tomography (MDCT) coronary angiography. EATV was measured as the sum of cross-sectional epicardial fat area on CT images, from the lower surface of the left pulmonary artery origin to the apex. Subjects were segregated into the CAD group (coronary luminal narrowing > 50%) and non-CAD group., Results: EATV/body surface area (BSA) was higher among men in the CAD group than in the non-CAD group (62 ± 13 vs. 33 ± 10 cm3/m2, p < 0.0001), but did not differ significantly among women in the 2 groups (49 ± 18 vs. 42 ± 9 cm3/m2, not significant). Multivariate logistic analysis showed that EATV/BSA was the single predictor for >50% coronary luminal narrowing in men (p < 0.0001). Predictors excluded were age, body mass index, hypertension, diabetes mellitus, and hyperlipidemia., Conclusions: Increased EATV is strongly associated with coronary atherosclerosis in men.

Recent accumulating evidence suggests that innate immunity is associated with obesity-induced chronic inflammation and metabolic disorders. Here, we show that a Toll-like receptor (TLR) protein, radioprotective 105 (RP105)/myeloid differentiation protein (MD)-1 complex, contributes to high-fat diet (HFD)-induced obesity, adipose tissue inflammation, and insulin resistance. An HFD dramatically increased RP105 mRNA and protein expression in stromal vascular fraction of epididymal white adipose tissue (eWAT) in wild-type (WT) mice. RP105 mRNA expression also was significantly increased in the visceral adipose tissue of obese human subjects relative to nonobese subjects. The RP105/MD-1 complex was expressed by most adipose tissue macrophages (ATMs). An HFD increased RP105/MD-1 expression on the M1 subset of ATMs that accumulate in eWAT. Macrophages also acquired this characteristic in coculture with 3T3-L1 adipocytes. RP105 knockout (KO) and MD-1 KO mice had less HFD-induced adipose tissue inflammation, hepatic steatosis, and insulin resistance compared with wild-type (WT) and TLR4 KO mice. Finally, the saturated fatty acids, palmitic and stearic acids, are endogenous ligands for TLR4, but they did not activate RP105/MD-1. Thus, the RP105/MD-1 complex is a major mediator of adipose tissue inflammation independent of TLR4 signaling and may represent a novel therapeutic target for obesity-associated metabolic disorders.

Objectives: The purpose of this report was to assess the link between macrophage polarization in epicardial adipose tissue and atherosclerosis in patients with coronary artery disease (CAD)., Background: Macrophage accumulation enhances chronic inflammation in adipose tissue, but macrophage phenotypic change in human epicardial adipose tissue and its role in atherogenesis are unknown., Methods: Samples were obtained from epicardial and subcutaneous adipose tissue during elective cardiac surgery (CAD, n = 38; non-CAD, n = 40). Infiltration of M1/M2 macrophages was investigated by immunohistochemical staining with antibodies against CD11c and CD206, respectively. Expression of pro- and anti-inflammatory adipocytokines in adipose tissue was evaluated by real-time quantitative polymerase chain reaction., Results: Infiltration of macrophages and expression of pro- and anti-inflammatory cytokines were enhanced in epicardial fat of patients with CAD compared with that in non-CAD patients (p < 0.05). The ratio of M1/M2 macrophages was positively correlated with the severity of CAD (r = 0.312, p = 0.039). Furthermore, the expression of pro-inflammatory cytokines was positively correlated, and the expression of anti-inflammatory cytokines was negatively correlated with the ratio of M1/M2 macrophages in epicardial adipose tissue of CAD patients. By contrast, there was no significant difference in macrophage infiltration and cytokine expression in subcutaneous adipose tissue between the CAD and non-CAD groups., Conclusions: The ratio of M1/M2 macrophages in epicardial adipose tissue of CAD patients is changed compared with that in non-CAD patients. Human coronary atherosclerosis is associated with macrophage polarization in epicardial adipose tissue., (Copyright © 2011 American College of Cardiology Foundation. Published by Elsevier Inc. All rights reserved.)

Objective: We have provided evidence that saturated fatty acids, which are released from adipocytes via macrophage-induced adipocyte lipolysis, serve as a naturally occurring ligand for the Toll-like receptor (TLR) 4 complex in macrophages, thereby aggravating obesity-induced adipose tissue inflammation. The aim of this study was to identify the molecule(s) activated in adipose tissue macrophages in obesity., Research Design and Methods: We performed a cDNA microarray analysis of coculture of 3T3-L1 adipocytes and RAW264 macrophages. Cultured adipocytes and macrophages and the adipose tissue of obese mice and humans were used to examine mRNA and protein expression., Results: We found that macrophage-inducible C-type lectin (Mincle; also called Clec4e and Clecsf9), a type II transmembrane C-type lectin, is induced selectively in macrophages during the interaction between adipocytes and macrophages. Treatment with palmitate, a major saturated fatty acid released from 3T3-L1 adipocytes, induced Mincle mRNA expression in macrophages at least partly through the TLR4/nuclear factor (NF)-κB pathway. Mincle mRNA expression was increased in parallel with macrophage markers in the adipose tissue of obese mice and humans. The obesity-induced increase in Mincle mRNA expression was markedly attenuated in C3H/HeJ mice with defective TLR4 signaling relative to control C3H/HeN mice. Notably, Mincle mRNA was expressed in bone-marrow cell (BMC)-derived proinflammatory M1 macrophages rather than in BMC-derived anti-inflammatory M2 macrophages in vitro., Conclusions: Our data suggest that Mincle is induced in adipose tissue macrophages in obesity at least partly through the saturated fatty acid/TLR4/NF-κB pathway, thereby suggesting its pathophysiologic role in obesity-induced adipose tissue inflammation.

It has been hypothesized that epicardial fat, a local visceral fat depot with close proximity to coronary arteries, may serve as a source of inflammatory cytokines and cells in coronary atherosclerotic lesions. Here, we characterized infiltration of inflammatory cells and expression of adipocytokines in epicardial adipose tissue in patients with and without coronary artery disease (CAD). Pare samples were obtained from epicardial and subcutaneous adipose tissue during elective cardiac surgery (CAD, n = 8; non-CAD, n = 9). Inflammatory cell infiltration was investigated by immunohistochemical staining using antibodies against CD3, CD4, CD8 and CD68. Expression of adipocytokines was evaluated by real-time quantitative reverse transcription-polymerase chain reaction. Infiltration of macrophages and CD8-positive T cells in the epicardial adipose tissue in the CAD group was greater than that in the non-CAD group. In contrast, there was no significant difference between the two groups in the number of inflammatory cells in subcutaneous adipose tissue. No statistical difference could be found between the CAD group and the non-CAD group in the expression levels of adiponectin and inflammatory cytokines in epicardial adipose tissue. Our findings suggest that inflammatory cell infiltration is enhanced in epicardial adipose tissue, but not in subcutaneous fat, in patients with coronary artery disease. Chronic inflammation in epicardial fat may influence the pathogenesis of coronary atherosclerosis.