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Introduction: Eicosanoids play an important role in regulating inflammation response, which influences the development of heart failure (HF). However, the association between eicosanoids and the risk of HF remains unclear. Hypothesis: We hypothesize that eicosanoid metabolites are associated with incident HF and may improve HF prediction. Methods: We measured plasma eicosanoids via liquid chromatography-mass spectrometry among HF-free participants at visit 2 (1990-1992) from the Atherosclerosis Risk in Communities (ARIC) study. The Cox proportional hazard regression was performed to evaluate the relationship between eicosanoids and incident HF controlling for clinical risk factors. The least absolute shrinkage and selection operator was applied to identify a representative subset of eicosanoids towards constructing an eicosanoid risk score (ERS). We further conducted genome-wide association analyses to examine the genetic determinants for HF related eicosanoids in black and white participants respectively. Results: During an average of 21 years of follow up, 2,202 (28.0 % blacks, 50.3% women) out of 9,519 participants developed HF. Out of 200 eicosanoids analyzed, six with hazard ratio between 0.89 to 1.10 were found associated with the risk of HF (FDR UGT2B7 , where its T allele was associated with lower EPA [M-H+Acetate] level while positively affect the risk of HF and systolic blood pressure level. ERS constructed from 52 eicosanoids showed a 39% increase in HF risk per SD increment and twice the risk between the highest and the lowest ERS quartile (p < 0.001). The addition of ERS to the HF 10-years prediction model modestly improved the C-statistics from 0.799 to 0.808, 95%CI ΔC : 0.004-0.015. Conclusion: We identified a set of eicosanoids that significantly associated with increased risk of HF. The contributing genetic variation of eicosanoids may depict the biological pathways related to HF.

CD11c is a canonical dendritic cell (DC) marker with poorly defined functions in the immune system. Here, we found that blocking CD11c on human peripheral blood mononuclear cell‐derived DCs (MoDCs) inhibited the proliferation of CD4+ T cells and the differentiation into IFN‐γ‐producing T helper 1 (Th1) cells, which were critical in acute graft‐versus‐host disease (aGVHD) pathogenesis. Using allogeneic bone marrow transplantation (allo‐BMT) murine models, we consistently found that CD11c‐deficient recipient mice had alleviated aGVHD symptoms for the decreased IFN‐γ‐expressing CD4+ Th1 cells and CD8+ T cells. Transcriptional analysis showed that CD11c participated in several immune regulation functions including maintaining antigen presentation of APCs. CD11c‐deficient bone marrow‐derived DCs (BMDCs) impaired the antigen presentation function in coculture assay. Mechanistically, CD11c interacted with MHCII and Hsp90 and participated in the phosphorylation of Akt and Erk1/2 in DCs after multiple inflammatory stimulations. Therefore, CD11c played crucial roles in triggering aGVHD and might serve as a potential target for the prevention and treatment of aGVHD., CD11c‐deficient recipient mice had alleviated aGVHD symptoms for the decreased IFN‐γ‐expressing CD4+ Th1 cells and CD8+ T cells during mice allo‐BMT. CD11c participated in triggering aGVHD and maintaining antigen presentation function of APCs. Mechanistically, CD11c interacted with MHCII and Hsp90 and participated in the phosphorylation of Akt and Erk1/2 in DCs after multiple inflammatory stimulations.

Accumulating evidence suggests that chronic inflammation of metabolic tissues plays a causal role in obesity-induced insulin resistance. Yet, how specific endothelial factors impact metabolic tissues remains undefined. Bone morphogenetic protein (BMP)–binding endothelial regulator (BMPER) adapts endothelial cells to inflammatory stress in diverse organ microenvironments. Here, we demonstrate that BMPER is a driver of insulin sensitivity. Both global and endothelial cell-specific inducible knockout of BMPER cause hyperinsulinemia, glucose intolerance and insulin resistance without increasing inflammation in metabolic tissues in mice. BMPER can directly activate insulin signaling, which requires its internalization and interaction with Niemann-Pick C1 (NPC1), an integral membrane protein that transports intracellular cholesterol. These results suggest that the endocrine function of the vascular endothelium maintains glucose homeostasis. Of potential translational significance, the delivery of BMPER recombinant protein or its overexpression alleviates insulin resistance and hyperglycemia in high-fat diet-fed mice and Leprdb/db (db/db) diabetic mice. We conclude that BMPER exhibits therapeutic potential for the treatment of diabetes., Type 2 diabetes is associated with chronic inflammation and is characterized by insulin resistance. Here, the authors identify a crucial role for endothelial BMPER function in glucose homeostasis, and BMPER overexpression was shown to alleviate insulin resistance and hyperglycemia in diabetic mice.

CD11c+ macrophages/dendritic cells (MDCs) are increased and display the classically activated M1-like phenotype in obese adipose tissue (AT) and may contribute to AT inflammation and insulin resistance. Stat1 is a key transcription factor for MDC polarization into the M1-like phenotype. Here, we examined the role of Stat1 in obesity-induced AT MDC polarization and inflammation and insulin resistance using mice with specific knockout of Stat1 in MDCs (cKO). Stat1 was upregulated and phosphorylated, indicating activation, early and persistently in AT and AT MDCs of wild-type mice fed a high-fat diet (HFD). Compared with littermate controls, cKO mice fed an HFD (16 weeks) had reductions in MDC (mainly CD11c+ macrophage) M1-like polarization and interferon-γ–expressing T-helper type 1 (Th1) cells but increases in interleukin 5–expressing Th2 cells and eosinophils in perigonadal and inguinal AT, and enhanced inguinal AT browning, with increased energy expenditure. cKO mice compared with controls also had significant reductions in triglyceride content in the liver and skeletal muscle and exhibited improved insulin sensitivity and glucose tolerance. Taken together, our results demonstrate that Stat1 in MDCs plays an important role in obesity-induced MDC M1-like polarization and AT inflammation and contributes to insulin resistance and metabolic dysfunctions in obese mice.

Intermediate monocytes (iMo; CD14+CD16+) increase in number in the circulation of patients with unstable coronary artery disease (CAD), and their recruitment to inflamed arteries is implicated in events leading to mortality following MI. Monocyte recruitment to inflamed coronary arteries is initiated by high affinity β2-integrin (CD11c/CD18) that activates β1-integrin (VLA-4) to bind endothelial VCAM-1. How integrin binding under shear stress mechanosignals a functional shift in iMo toward an inflammatory phenotype associated with CAD progression is unknown. Whole blood samples from patients treated for symptomatic CAD including non-ST elevation MI, along with healthy age-matched subjects, were collected to assess chemokine and integrin receptor levels on monocytes. Recruitment on inflamed human aortic endothelium or rVCAM-1 under fluid shear stress was assessed using a microfluidic-based artery on a chip (A-Chip). Membrane upregulation of high affinity CD11c correlated with concomitant activation of VLA-4 within focal adhesive contacts was required for arrest and diapedesis across inflamed arterial endothelium to a greater extent in non-ST elevation MI compared with stable CAD patients. The subsequent conversion of CD11c from a high to low affinity state under fluid shear activated phospho-Syk– and ADAM17-mediated proteolytic cleavage of CD16. This marked the conversion of iMo to an inflammatory phenotype associated with nuclear translocation of NF-κB and production of IL-1β+. We conclude that CD11c functions as a mechanoregulator that activates an inflammatory state preferentially in a majority of iMo from cardiac patients but not healthy patients.

Obesity is becoming an epidemic in the United States and worldwide and increases risk for many diseases, particularly insulin resistance, type 2 diabetes mellitus, and cardiovascular disease. The mechanisms linking obesity with these diseases remain incompletely understood. Over the past 2 to 3 decades, it has been recognized that in obesity, inflammation, with increased accumulation and inflammatory polarization of immune cells, takes place in various tissues, including adipose tissue, skeletal muscle, liver, gut, pancreatic islet, and brain and may contribute to obesity-linked metabolic dysfunctions, leading to insulin resistance and type 2 diabetes mellitus. Therapies targeting inflammation have shed light on certain obesity-linked diseases, including type 2 diabetes mellitus and atherosclerotic cardiovascular disease, but remain to be tested further and confirmed in clinical trials. This review focuses on inflammation in adipose tissue and its potential role in insulin resistance associated with obesity.

Background: Hypertriglyceridemia (HTG) increases the risk for atherosclerotic cardiovascular disease, but underlying mechanisms are incompletely understood. Circulating monocytes play an important role in atherogenesis by infiltrating arterial walls, where they differentiate into macrophages. We tested the hypothesis that HTG is mechanistically linked to atherogenesis by altering the monocyte phenotype and infiltration into atherosclerotic lesions in a model of diet-induced atherogenesis in Ldlr−/− mice. Methods: HTG was induced in male Ldlr−/− mice, fed a Western, high-fat high-cholesterol diet, by daily injection of poloxamer 407 (P407), a lipoprotein lipase inhibitor, for seven weeks. Atherosclerosis, monocyte phenotypes, and monocyte migration into atherosclerotic lesions were determined by well-validated methods. Results: Compared with the saline control, P407 injection in Ldlr−/− mice rapidly induced profound and persistent HTG, modestly elevated plasma cholesterol levels, and increased levels of triglyceride and cholesterol carried in very-low-density lipoprotein and low-density lipoprotein. Unexpectedly, mice receiving P407 versus saline control showed less atherosclerosis. Following induction of HTG by P407, CD36+ (also CD11c+), but not CD36− (CD11c−), monocytes showed early increases in lipid accumulation, but the number of CD36+ (not CD36−) monocytes was dramatically decreased afterwards in the circulation until the end of the test. Concurrently, CD36+ (CD11c+) monocyte migration into atherosclerotic lesions was also reduced in mice receiving P407 versus controls. Conclusions: P407 induced severe HTG, but reduced atherosclerosis, in Ldlr−/− mice, possibly because of profound reductions of circulating CD36+ (CD11c+) monocytes, leading to decreased monocyte migration into atherosclerotic lesions.

PURPOSE OF REVIEW: Recent studies indicate an association between hypertriglyceridemia (HTG) and atherosclerotic cardiovascular disease (ASCVD). The purpose of this review is to discuss the potential mechanism connecting HTG and ASCVD risk and the potential efficacy of HTG-targeting therapies in ASCVD prevention. RECENT FINDINGS: HTG, with elevations in triglyceride-rich lipoproteins (TGRL) and their remnants, are causal ASCVD risk factors. The mechanisms whereby HTG increases ASCVD risk are not well understood but may include multiple factors. Inflammation plays a crucial role in atherosclerosis. TGRL compared to low-density lipoproteins (LDL) correlate better with inflammation. TGRL remnants can penetrate endothelium and interact with macrophages leading to foam cell formation and inflammation in arterial walls, thereby contributing to atherogenesis. In addition, circulating monocytes can take up TGRL and become lipid-laden foamy monocytes, which infiltrate the arterial wall and may also contribute to atherogenesis. Novel therapies targeting HTG or inflammation are in development and have potential of reducing residual ASCVD risk associated with HTG. SUMMARY: Clinical and preclinical studies show a causal role of HTG in promoting ASCVD, in which inflammation plays a vital role. Novel therapies targeting HTG or inflammation have potential of reducing residual ASCVD risk.

Objective: A Mediterranean diet supplemented with olive oil and nuts prevents cardiovascular disease in clinical studies, but the underlying mechanisms are incompletely understood. We investigated whether the preventive effect of the diet could be due to inhibition of atherosclerosis and foamy monocyte formation in Ldlr –/– mice fed with a diet in which milkfat in a Western diet (WD) was replaced with extra-virgin olive oil and nuts (EVOND). Approach and Results: Ldlr –/– mice were fed EVOND or a Western diet for 3 (or 6) months. Compared with the Western diet, EVOND decreased triglyceride and cholesterol levels but increased unsaturated fatty acid concentrations in plasma. EVOND also lowered intracellular lipid accumulation in circulating monocytes, indicating less formation of foamy monocytes, compared with the Western diet. In addition, compared with the Western diet, EVOND reduced monocyte expression of inflammatory cytokines, CD36, and CD11c, with decreased monocyte uptake of oxLDL (oxidized LDL [low-density lipoprotein]) ex vivo and reduced CD11c + foamy monocyte firm arrest on vascular cell adhesion molecule-1 and E-selectin–coated slides in an ex vivo shear flow assay. Along with these changes, EVOND compared with the Western diet reduced the number of CD11c + macrophages in atherosclerotic lesions and lowered atherosclerotic lesion area of the whole aorta and aortic sinus. Conclusions: A diet enriched in extra-virgin olive oil and nuts, compared with a Western diet high in saturated fat, lowered plasma cholesterol and triglyceride levels, inhibited foamy monocyte formation, inflammation, and adhesion, and reduced atherosclerosis in Ldlr –/– mice.

Context The effects of dietary intake of different fatty acids and pharmacological use of fatty acids, specifically long-chain n-3 polyunsaturated fatty acids (LC n-3 PUFAs), on cardiovascular health and atherosclerotic cardiovascular disease (ASCVD) prevention have been examined in a large number of observational studies and clinical trials. This review summarizes recent data and discusses potential mechanisms. Evidence acquisition The review is based on the authors’ knowledge of the field supplemented by a PubMed search using the terms seafood, fish oil, saturated fatty acids, omega-3 fatty acids, eicosapentaenoic acid, docosahexaenoic acid, polyunsaturated fatty acids, monounsaturated fatty acids, and ASCVD. Evidence synthesis We mainly discuss the recent clinical trials that examine the effects of different types of dietary fatty acids and pharmacological use of n-3 PUFA products on ASCVD prevention and the potential mechanisms. Conclusions While replacement of dietary saturated fat with unsaturated fat, polyunsaturated fat in particular, or intake of LC n-3 PUFA–rich seafood has generally shown benefit for ASCVD prevention and is recommended for cardiovascular benefits, data on effects of n-3 PUFA products on ASCVD health are inconsistent. However, recent clinical trials support benefits of prescription EPA in ASCVD prevention. n-3 PUFAs may contribute to ASCVD prevention through multiple mechanisms, including lowering plasma triglyceride levels, anti-inflammatory effects, antithrombotic effects, and effects on endothelial function.

Low-grade, sustained inflammation in white adipose tissue (WAT) characterizes obesity and coincides with type 2 diabetes mellitus (T2DM). However, pharmacological targeting of inflammation lacks durable therapeutic effects in insulin-resistant conditions. Through a computational screen, we discovered that the FDA-approved rheumatoid arthritis drug auranofin improved insulin sensitivity and normalized obesity-associated abnormalities, including hepatic steatosis and hyperinsulinemia in mouse models of T2DM. We also discovered that auranofin accumulation in WAT depleted inflammatory responses to a high-fat diet without altering body composition in obese wild-type mice. Surprisingly, elevated leptin levels and blunted beta-adrenergic receptor activity achieved by leptin receptor deletion abolished the antidiabetic effects of auranofin. These experiments also revealed that the metabolic benefits of leptin reduction were superior to immune impacts of auranofin in WAT. Our studies uncover important metabolic properties of anti-inflammatory treatments and contribute to the notion that leptin reduction in the periphery can be accomplished to treat obesity and T2DM.

SUMMARYLow-grade, sustained inflammation in white adipose tissue (WAT) characterizes obesity and frequently coincides with insulin resistance and type 2 diabetes (T2D). However, pharmacological targeting of WAT inflammation lacks durable therapeutic effects. Through a computational screen, we identified the FDA-approved rheumatoid arthritis drug auranofin is a putative small molecule for obesity treatment. We discovered that allometrically scaled safe auranofin doses homed to WAT and improved insulin sensitivity in obese wild-type mice. Auranofin treatment also normalized other obesity-associated abnormalities, including hepatic steatosis and hyperinsulinemia. Surprisingly, the anti-diabetic effects of auranofin required leptin lowering and beta-adrenergic receptors in WAT. These metabolic benefits of leptin reduction were superior to any immune impacts of auranofin in WAT. Our studies reveal important metabolic properties of anti-inflammatory treatments and contribute to the notion that leptin reduction in the periphery can be accomplished to treat obesity and T2D.

The vascular endothelium is present within metabolic organs and actively regulates energy metabolism. Here we show osteocalcin, recognized as a bone-secreted metabolic hormone, is expressed in mouse primary endothelial cells isolated from heart, lung and liver. In human osteocalcin promoter-driven green fluorescent protein transgenic mice, green fluorescent protein signals are enriched in endothelial cells lining aorta, small vessels and capillaries and abundant in aorta, skeletal muscle and eye of adult mice. The depletion of lipoprotein receptor-related protein 1 induces osteocalcin through a Forkhead box O -dependent pathway in endothelial cells. Whereas depletion of osteocalcin abolishes the glucose-lowering effect of low-density lipoprotein receptor-related protein 1 depletion, osteocalcin treatment normalizes hyperglycemia in multiple mouse models. Mechanistically, osteocalcin receptor-G protein-coupled receptor family C group 6 member A and insulin-like-growth-factor-1 receptor are in the same complex with osteocalcin and required for osteocalcin-promoted insulin signaling pathway. Therefore, our results reveal an endocrine/paracrine role of endothelial cells in regulating insulin sensitivity, which may have therapeutic implications in treating diabetes and insulin resistance through manipulating vascular endothelium., The vascular endothelium contributes to metabolic regulation, however, the underlying mechanisms are not fully understood. Here the authors show that endothelial low-density lipoprotein receptor-related protein 1 regulates glucose homeostasis via osteocalcin expression.

Jak/STAT pathway plays key roles in inflammation and is highly activated in adipose tissue (AT) in obesity. Recently, inhibition of the Jak/STAT pathway with baricitinib, a Jak1/Jak2 inhibitor, has been demonstrated to accelerate clinical improvements in a trial of hospitalized patients with COVID-19, who had a mean BMI of 32. Currently, we aimed to examine effects of long-term treatment with baricitinib on AT inflammation and metabolism in diet-induced obese mice. Starting from 3 months old, male C57BL/6J mice were fed high fat diet (HFD) and concurrently received daily oral gavage of baricitinib (10mg/kg) or vehicle for 12 weeks. Compared to vehicle control, baricitinib treatment significantly improved insulin resistance examined by insulin tolerance test and increased UCP1 (a key browning marker) expression in perigonadal (pAT) and inguinal AT (iAT), but did not affect weight gain and AT mass. Strikingly, total T cells were reduced by ~50% in iAT and pAT in baricitinib group vs. control group. CD4+ IFNγ-expressing Th1 cells, IL5-expressing Th2 cells, and TNFα-expressing T cells were decreased in pAT, but not in iAT, of mice from baricitinib group vs. control group. Unexpectedly, percentage of TNFα-expressing cells in CD8+ T cells were higher in iAT of baricitinib-treated mice than controls. Finally, baricitinib compared to control reduced M1/M2 ratio in pAT, but not iAT, and reduced eosinophils in iAT and pAT. Baricitinib inhibition of Jak/STAT pathway in diet-induced obese mice improved insulin sensitivity and changed immune cells in AT, with dramatic reductions of T cells in particular, indicating an important role of Jak/STAT-mediated inflammation in metabolism in obesity. Given the fact that obesity and insulin resistance are associated with increased severity of COVID-19, our data also point to the need for further studies on AT immune cells, COVID-19, and baricitinib. Disclosure Z. Lian: None. X. Perrard: None. C. M. Ballantyne: Advisory Panel; Self; Amarin Corporation plc, Arrowhead Pharmaceuticals, Inc., Pfizer Inc., Consultant; Self; Amgen Inc., CSL Behring, Intercept Pharmaceuticals, Inc., Novartis Pharmaceuticals Corporation, Novo Nordisk, Regeneron Pharmaceuticals Inc., Research Support; Self; Abbott, Amgen Inc., Ionis Pharmaceuticals, Novartis Pharmaceuticals Corporation, Regeneron Pharmaceuticals Inc., Roche Diagnostic USA. H. Wu: None.

CD11c+ macrophages/dendritic cells (MDCs) are increased and display classically activated M1-like phenotype in obese adipose tissue (AT) and may contribute to AT inflammation and insulin resistance. Stat1 is a key transcription factor for MDC polarization into M1-like phenotype. Here, we examined the role of Stat1 in obesity-induced AT MDC polarization and inflammation and insulin resistance using mice with specific knockout of Stat1 in MDCs (cKO). Stat1 was upregulated and phosphorylated, indicating activation, early and persistently in AT and AT MDCs of wild-type mice fed high-fat diet (HFD). Compared to littermate controls, cKO mice fed HFD (16 weeks) had reductions in MDC (mainly CD11c+ macrophage) M1-like polarization and interferon-g–expressing T helper type 1 (Th1) cells, but increases in interleukin-5–expressing Th2 cells and eosinophils in perigonadal and inguinal AT, and enhanced inguinal AT browning, with increased energy expenditure. cKO mice compared with controls also had significant reductions in triglyceride content in the liver and skeletal muscle and exhibited improved insulin sensitivity and glucose tolerance. Taken together, our results demonstrated that Stat1 in MDCs plays an important role in obesity-induced MDC M1-like polarization and AT inflammation and contributes to insulin resistance and metabolic dysfunctions in obese mice.

Introduction: Clinical trials suggest that low-saturated fat diet (LSFD) may reduce the risk of atherosclerotic cardiovascular disease (ASCVD) in subjects with hypertriglyceridemia (HTG). Monocytes play crucial roles in atherogenesis. Hypothesis: LSFD vs high-saturated fat diet (HSFD) improves monocyte phenotypes, thereby reducing ASCVD risk, in subjects with HTG. Methods: Subjects with HTG and metabolic syndrome (MetS, n=19) received isocaloric LSFD (~25% of calories from fat, 5% from saturated fat) and HSFD (~52% of calories from fat, 25% from saturated fat) in randomized order for 4 days (days 1-4) plus a breakfast on day 5, separated by a 4- to 6-week washout period. Blood was drawn on day 1 fasting before the diets and 3 times on day 5 (fasting before the breakfast and 4 and 6 hours postprandial) for measurement of lipid profile and analyses of monocyte phenotypes by flow cytometry and monocyte adhesion by a lab-on-a-chip microfluidic assay. Results: On day 5, LSFD, compared to HSFD, induced lower plasma levels of postprandial total triglyceride and LDL-triglyceride and fasting and postprandial total cholesterol, LDL-cholesterol, and small dense LDL-cholesterol. Compared to HSFD, LSFD reduced fasting and postprandial intracellular lipid accumulation in classical and intermediate monocytes examined by nile red staining and indicated by side scatter value of flow cytometric analysis. LSFD versus HSFD also reduced ex vivo uptake of oxidized LDL by classical monocytes at 4 hours postprandially and by intermediate monocytes in fasting state. Surface levels of molecules involved in monocyte adhesion/migration, including CD11c, CD81, and CCR2, were lower on monocytes with LSFD than with HSFD. Consistently, LSFD compared to HSFD reduced monocyte adhesion to VCAM-1. Intracellular levels of cytokines such as IL-1β, TNFα, and IL-6 in monocytes showed no difference between the two diets. Conclusions: In subjects with HTG and MetS, short-term LSFD compared to HSFD reduces monocyte intracellular lipid accumulation and improves monocyte phenotypes with reductions in monocyte adhesion and oxidized LDL uptake. These findings highlight the importance of diet composition in monocyte phenotypes and possibly atherosclerosis risks in patients with HTG and MetS.

Obesity fosters low-grade inflammation in white adipose tissue (WAT) that may contribute to the insulin resistance that characterizes type 2 diabetes mellitus (T2DM). However, the causal relationship of these events remains unclear. The established dominance of signal transducer and activator of transcription 1 (STAT1) function in the immune response suggests an obligate link between inflammation and the co-morbidities of obesity. To this end, we sought to determine how STAT1 activity in white adipocytes affects insulin sensitivity. STAT1 expression in WAT inversely correlated with fasting plasma glucose in both obese mice and humans. Metabolomic and gene expression profiling established STAT1 deletion in adipocytes (STAT1a-KO­­­) enhanced mitochondrial function and accelerated TCA cycle flux coupled with reduced fat cell size in subcutaneous WAT depots. STAT1a-KO reduced WAT inflammation, but insulin resistance persisted in obese mice. Rather, elimination of type I cytokine interferon gamma (IFNg) activity enhanced insulin sensitivity in diet-induced obesity. Our findings reveal a permissive mechanism that bridges WAT inflammation to whole-body insulin sensitivity.

CD11c(+) macrophages/dendritic cells (MDCs) are increased and display the classically activated M1-like phenotype in obese adipose tissue (AT) and may contribute to AT inflammation and insulin resistance. Stat1 is a key transcription factor for MDC polarization into the M1-like phenotype. Here, we examined the role of Stat1 in obesity-induced AT MDC polarization and inflammation and insulin resistance using mice with specific knockout of Stat1 in MDCs (cKO). Stat1 was upregulated and phosphorylated, indicating activation, early and persistently in AT and AT MDCs of wild-type mice fed a high-fat diet (HFD). Compared with littermate controls, cKO mice fed an HFD (16 weeks) had reductions in MDC (mainly CD11c(+) macrophage) M1-like polarization and interferon-γ–expressing T-helper type 1 (Th1) cells but increases in interleukin 5–expressing Th2 cells and eosinophils in perigonadal and inguinal AT, and enhanced inguinal AT browning, with increased energy expenditure. cKO mice compared with controls also had significant reductions in triglyceride content in the liver and skeletal muscle and exhibited improved insulin sensitivity and glucose tolerance. Taken together, our results demonstrate that Stat1 in MDCs plays an important role in obesity-induced MDC M1-like polarization and AT inflammation and contributes to insulin resistance and metabolic dysfunctions in obese mice.

Background: Aging (middle age) is usually associated with obesity and progressive low-grade inflammation in adipose tissue. However, how immune components in adipose tissue respond to aging is still not fully uncovered. Here, we sought to examine immune cells and inflammation in adipose tissue in aging mice. Methods: Bodyweight and insulin sensitivity were measured in 12-month-old (aging) and 3-month-old (young) C57BL/6J mice on a low-fat normal diet. UCP1 expression was examined in white adipose tissue after stimulation. The immune-cell composition and phenotypes in adipose tissue were analyzed by flow cytometry. The suppressive functions of adipose tissue-resident T regulatory cells (aTregs) for conventional T cell proliferation were evaluated by CFSE-labeling proliferation assay in vitro. Results: Compared to young mice, aging mice exhibited adipose tissue expansion and insulin resistance. UCP1 was reduced in adipose tissue, indicating impaired adipose tissue browning, in aging mice compared to young mice. The frequency of resident T cells and macrophages was increased in adipose tissue of aging mice compared to those of young mice. Moreover, the Th1 subset of T cells and the M1 subset of macrophages dominated in their parent population in adipose tissue of aging mice. In contrast to diet-induced obesity that reduced aTregs, the frequency of aTregs was increased in old mice compared to young mice. However, the anti-inflammatory cytokines IL10 and inflammation-inhibitory marker CTLA4 were reduced on aTregs in aging mice than young mice. The proliferative assay showed that the suppressive capacity of Treg cell on conventional T cell proliferation was impaired in aging mice. Conclusion: Aging in mice is associated with increased aTregs, which have reduced anti-inflammatory functions and may, therefore, contribute to increased Th1 and M1 inflammation in adipose tissue, leading to metabolic disorders in aging mice. Disclosure Z. Lian: None. X. Perrard: None. C.M. Ballantyne: Consultant; Self; Abbott, Akcea Therapeutics, Amarin Corporation, Amgen, Arrowhead Pharmaceuticals, Inc., AstraZeneca, Boehringer Ingelheim Pharmaceuticals, Inc., Corvidia, Denka-Seiken Co., Ltd., Esperion Therapeutics, Inc., Gilead Sciences, Inc., Janssen Pharmaceuticals, Inc., Matinas BioPharma, Merck & Co., Inc., Novartis Pharmaceuticals Corporation, Novo Nordisk Inc., Regeneron Pharmaceuticals, Roche Diagnostic USA, Sanofi. Research Support; Self; Abbott, Akcea Therapeutics, Amgen, Esperion Therapeutics, Inc., Novartis Pharmaceuticals Corporation, Regeneron Pharmaceuticals, Roche Diagnostic USA. H. Wu: None. Funding American Diabetes Association (1-17-IBS-082 to H.W.); National Institutes of Health (R01HL098839); American Heart Association (16GRNT30410012)

Obesity is associated with chronic low-grade inflammation, reflecting significant alterations in the composition of immune cell populations that reside in white adipose tissue (WAT). The ensuing pro-inflammatory environment likely impinges on the metabolic functions of adipocytes and may partially explain the insulin resistance that characterizes type 2 diabetes mellitus (T2DM). We recently demonstrated ectopic expression of the microRNA miR-30a in the subcutaneous fat pad of diabetic mice coupled improved insulin sensitivity and increased energy expenditure with decreased ectopic fat deposition in the liver and reduced WAT inflammation. We subsequently pursued the notion that pharmacological inhibitors of inflammation that exhibit a gene expression profile similar to ectopic miR-30a expression in WAT should represent new drugs for insulin resistance and T2DM. To this end, we used the Broad Connectivity Map to analyze a library of small molecules that induce mRNA profiles similar to that of exogenous miR-30a expression in WAT. Through this process, we nominated the rheumatoid arthritis compound auranofin. Treatment of obese mice with auranofin improved insulin sensitivity and glucose tolerance. Auranofin treatment also normalized other obesity-associated abnormalities, including hepatic steatosis, serum insulin and leptin. Mechanistically, a combination of proteomics and immunophenotyping established auranofin likely exerts antidiabetic activities by opposing low-grade inflammation in WAT and ectopic liver fat accumulation. These studies reveal important metabolic properties of anti-inflammatory treatments that may be re-purposed as therapies for insulin resistance and T2DM. Disclosure A. Cox: None. P.M. Masschelin: None. N. Chernis: None. P. Saha: None. Z. Lian: None. J.B. Felix: None. K. Kim: None. H. Wu: None. S.M. Hartig: None. Funding American Diabetes Association (1-18-IBS-105 to S.M.H.); National Institutes of Health (R01DK114356)

White adipose tissue (WAT) is an endocrine organ that dynamically expands and contracts to meet the metabolic demands of the organism. However, prolonged excessive caloric intake overwhelms WAT depots, resulting in peripheral fat deposition, systemic glucose dysregulation, tissue fibrosis, insulin resistance, and type 2 diabetes mellitus. The chronic triggers that degrade WAT function remain undefined, hindering the development of effective strategies to treat obesity and prevent its co-morbidities. We have identified a microRNA, miR-30a, that potently stimulates subcutaneous adipose tissue metabolic flexibility and enhances systemic insulin sensitivity. In follow-up studies, we created a genetically engineered mouse model to conclusively show miR-30a expression in white adipocytes is antidiabetic. Obese mice modified to express miR-30a at elevated levels in adipose tissues maintain insulin sensitivity coupled with reduced hepatic steatosis. Proteomic profiling indicated that miR-30a targets Plasminogen Activator Inhibitor-1 (PAI-1) to limit pro-fibrotic programs that would otherwise restrict subcutaneous WAT expansion and decrease insulin sensitivity. While visceral WAT depots remain a site of significant fibrosis in mice, subcutaneous WAT fibrosis is epidemiologically linked to metabolic disease risk in adult humans. In obese humans, miR-30a expression negatively correlates with PAI-1 levels in subcutaneous WAT, supporting an anti-fibrotic role for miR-30a that ultimately defends insulin sensitivity. Collectively, our observations linking miR-30a expression to insulin sensitivity suggest a new method that restores WAT homeostasis. Disclosure N. Chernis: None. P. Saha: None. J.B. Felix: None. P.M. Masschelin: None. L. Lian: None. A. Cox: None. K. Kim: None. H. Wu: None. S.M. Hartig: None. Funding American Diabetes Association (1-18-IBS-105 to S.M.H.); National Institutes of Health (R01DK114356)

Obesity fosters low-grade inflammation in white adipose tissue (WAT) that may contribute to the insulin resistance that characterizes type 2 diabetes mellitus (T2DM). However, the causal relationship of these events remains unclear. The established dominance of signal transducer and activator of transcription 1 (STAT1) function in the immune response suggests an obligate link between inflammation and the co-morbidities of obesity. To this end, we sought to determine how STAT1 activity in white adipocytes affects insulin sensitivity. STAT1 expression in WAT inversely correlated with fasting plasma glucose in both obese mice and humans. Metabolomic and gene expression profiling established STAT1 deletion in adipocytes (STAT1a-KO) enhanced mitochondrial function and accelerated TCA cycle flux coupled with reduced fat cell size in subcutaneous WAT depots. STAT1a-KO reduced WAT inflammation, but insulin resistance persisted in obese mice. Rather, elimination of type I cytokine interferon gamma (IFNγ) activity enhanced insulin sensitivity in diet-induced obesity. Our findings reveal a permissive mechanism that bridges WAT inflammation to whole-body insulin sensitivity.

Background Accumulation of lipoprotein X (LpX) in blood can cause severe hypercholesterolemia and cutaneous xanthomas. Monocytes sensitively sense lipid changes in circulation and contribute to inflammation. However, how monocytes respond to LpX is undefined. Objective We examined the phenotype of monocytes from a patient, who had LpX, severe hypercholesterolemia, and extensive cutaneous xanthomas, and effects of semiselective plasmapheresis therapy (SPPT). Method Fluorescence-activated cell sorting and adhesion assays were used to examine monocyte phenotype and ex vivo oxidized low-density lipoprotein uptake and adhesion in the patient before and after treatment with SPPT. Effects of plasma from the patient on the phenotype and adhesion of monocytes from a healthy participant were determined. Results SPPT improved hypercholesterolemia and cutaneous xanthomas. Before treatment, the patient had lower frequency of nonclassical monocytes but higher frequency of intermediate monocytes than the control participant. Before treatment, monocytes from the patient with LpX showed more intracellular lipid accumulation, alterations in several cell surface markers and intracellular cytokines, as well as enhanced oxidized low-density lipoprotein uptake and reduced adhesion compared with control. After SPPT, the phenotypes of monocytes from the patient with LpX were similar to control monocytes. Incubation with plasma from the patient before treatment as compared with plasma from the control participant or the patient after treatment increased CD11c expression and adhesion of monocytes from a healthy participant. Conclusion LpX-induced hypercholesterolemia increased lipid accumulation and altered the phenotype of monocytes, which may contribute to cutaneous xanthoma development. Removal of LpX by SPPT reduced lipid accumulation and improved monocyte phenotype, likely contributing to xanthoma resolution.

Obesity is associated with chronic inflammation, which contributes to insulin resistance and type 2 diabetes mellitus. Under normal conditions, skeletal muscle is responsible for the majority of insulin-stimulated whole-body glucose disposal; thus, dysregulation of skeletal muscle metabolism can strongly influence whole-body glucose homeostasis and insulin sensitivity. Increasing evidence suggests that inflammation occurs in skeletal muscle in obesity and is mainly manifested by increased immune cell infiltration and proinflammatory activation in intermyocellular and perimuscular adipose tissue. By secreting proinflammatory molecules, immune cells may induce myocyte inflammation, adversely regulate myocyte metabolism, and contribute to insulin resistance via paracrine effects. Increased influx of fatty acids and inflammatory molecules from other tissues, particularly visceral adipose tissue, can also induce muscle inflammation and negatively regulate myocyte metabolism, leading to insulin resistance.

Context: Postprandial hyperlipidemia has been suggested to contribute to atherogenesis by inducing proinflammatory changes in monocytes. Individuals with metabolic syndrome (MS), shown to have higher blood triglyceride concentration and delayed triglyceride clearance, may thus have increased risk for development of atherosclerosis. Objective: Our objective was to examine fasting levels and effects of a high-fat meal on phenotypes of monocyte subsets in individuals with obesity and MS and in healthy controls. Design, Setting, Participants, Intervention: Individuals with obesity and MS and gender- and age-matched healthy controls were recruited. Blood was collected from participants after an overnight fast (baseline) and at 3 and 5 hours after ingestion of a high-fat meal. At each time point, monocyte phenotypes were examined by multiparameter flow cytometry. Main Outcome Measures: Baseline levels of activation markers and postprandial inflammatory response in each of the three monocyte subsets were measured. Results: At baseline, individuals with obesity and MS had higher proportions of circulating lipid-laden foamy monocytes than controls, which were positively correlated with fasting triglyceride levels. Additionally, the MS group had increased counts of nonclassical monocytes, higher CD11c, CX3CR1, and human leukocyte antigen-DR levels on intermediate monocytes, and higher CCR5 and tumor necrosis factor-α levels on classical monocytes in the circulation. Postprandial triglyceride increases in both groups were paralleled by upregulation of lipid-laden foamy monocytes. MS, but not control, subjects had significant postprandial increases of CD11c and percentages of IL-1β+ and tumor necrosis factor-α+ cells in nonclassical monocytes. Conclusions: Compared to controls, individuals with obesity and MS had increased fasting and postprandial monocyte lipid accumulation and activation.

Similar to obesity, aging is associated with visceral adiposity and insulin resistance. Inflammation in adipose tissue, mainly evidenced by increased accumulation and proinflammatory polarization of T cells and macrophages, has been well-documented in obesity and may contribute to the associated metabolic dysfunctions including insulin resistance. Studies show that increased inflammation, including inflammation in adipose tissue, also occurs in aging, so-called "inflamm-aging." Aging-associated inflammation in adipose tissue has some similarities but also differences compared to obesity-related inflammation. In particular, conventional T cells are elevated in adipose tissue in both obesity and aging and have been implicated in metabolic functions in obesity. However, the changes and also possibly functions of regulatory T cells (Treg) in adipose tissue are different in aging and obesity. In this review, we will summarize recent advances in research on the changes of these immune cells in adipose tissue with aging and obesity and discuss their possible contributions to metabolism and the potential of these immune cells as novel therapeutic targets for prevention and treatment of metabolic diseases associated with aging or obesity.

Background and aims Obesity-induced chronic inflammation is a key component in the pathogenesis of nonalcoholic fatty liver disease (NAFLD) and insulin resistance. Increased secretion of proinflammatory cytokines by macrophages in metabolic tissues promotes disease progression. In the diet-induced obesity (DIO) mouse model, activation of liver resident macrophages, or Kupffer cells (KCs), drives inflammatory responses, which recruits circulating macrophages and promotes fatty liver development, and ultimately contributes to impaired hepatic insulin sensitivity. Hepatic macrophages express the highest level of vitamin D receptors (VDRs) among nonparenchymal cells, whereas VDR expression is very low in hepatocytes. VDR activation exerts anti-inflammatory effects in immune cells. Approach and results Here we found that VDR activation exhibits strong anti-inflammatory effects in mouse hepatic macrophages, including those isolated from DIO livers, and mice with genetic loss of Vdr developed spontaneous hepatic inflammation at 6 months of age. Under the chronic inflammation conditions of the DIO model, VDR activation by the vitamin D analog calcipotriol reduced liver inflammation and hepatic steatosis, significantly improving insulin sensitivity. The hyperinsulinemic euglycemic clamp revealed that VDR activation greatly increased the glucose infusion rate, while hepatic glucose production was remarkably decreased. Glucose uptake in muscle and adipose did not show similar effects, suggesting that improved hepatic insulin sensitivity is the primary contributor to the beneficial effects of VDR activation. Finally, specifically ablating liver macrophages by treatment with clodronate liposomes largely abolished the beneficial metabolic effects of calcipotriol, confirming that VDR activation in liver macrophages is required for the antidiabetic effect. Conclusions Activation of liver macrophage VDRs by vitamin D ligands ameliorates liver inflammation, steatosis and insulin resistance. Our results suggest therapeutic paradigms for treatment of NAFLD and type 2 diabetes mellitus.

Background: Obesity is a global epidemic and major risk factor for insulin resistance and type 2 diabetes. Obesity is associated with low grade chronic inflammation of adipose tissue (AT). F4/80+CD11c+ macrophages/dendritic cells are increased and polarized into M1-like phenotypes in AT and may contribute to insulin resistance in mouse models of obesity. STAT1 is a transcription factor that play key roles in macrophage polarization into M1-like phenotypes. Hence, we investigated the role of CD11c+ macrophage/dendritic cell STAT1 in obesity-induced AT inflammation and insulin resistance. Methods: Mice with specific knockout of STAT1 in CD11c+ cells were generated by crossbreeding STAT1 fl/fl and CD11c-Cre mice. CD11c/STAT1 KO and littermate controls were fed either high fat diet (HFD, for 16 weeks) to induce obesity or normal diet (ND) as lean controls. We evaluated body composition, insulin sensitivity, gene expression of inflammatory markers, various immune cells and brown/beige adipogenesis markers in AT. Results: Perigonadal white AT (PWAT) and body weight were not significantly different between KO and control groups but liver weight and liver-to-body weight ratio were significantly reduced in obese KO mice (p Conclusion: Our results show the critical role of macrophage/dendritic cell STAT1 in obesity-induced AT inflammation and insulin resistance. Disclosure A. Kalathookunnel Antony: None. X.D. Perrard: None. Z. Lian: None. J. Perrard: None. L. Hennighausen: None. C.W. Smith: None. C.M. Ballantyne: Research Support; Self; Abbott, Amarin Corporation, Amgen Inc., Esperion Therapeutics, Ionis Pharmaceuticals, Inc., Novartis Pharmaceuticals Corporation, Pfizer Inc., Regeneron Pharmaceuticals, Inc., Roche Diagnostics Corporation, Sanofi. Consultant; Self; Abbott, Amarin Corporation, Amgen Inc., AstraZeneca, Boehringer Ingelheim Pharmaceuticals, Inc., Eli Lilly and Company, Esperion Therapeutics, Ionis Pharmaceuticals, Inc., Matinas BioPharma, Merck & Co., Inc., Novartis Pharmaceuticals Corporation, Novo Nordisk Inc., Pfizer Inc., Regeneron Pharmaceuticals, Inc., Roche Diagnostics Corporation, Sanofi. H. Wu: None.

Adipose tissue performs immunoregulatory functions in addition to fat storage. Various T cells in different fat depots either help maintain metabolic homeostasis under healthy conditions or contribute to metabolic disorders in pathological conditions such as obesity, diabetes, cardiovascular diseases, or even cancer. These T cells play critical roles in immunometabolism, which refers to the intersection of immunity and metabolism. Numerous studies have examined the presence and changes of different T cell subsets, including helper T cells, regulatory T cells, cytotoxic T cells, and natural killer T cells, in adipose depots in health and diseases. In this review, we will discuss the adipose tissue niches that influence the patterns and functions of T cell subsets and in turn the impact of these T cells on cell- or body-based immunometabolism accounting for health and obesity.

CD11c, also known as integrin alpha X, is the most widely used defining marker for dendritic cells (DCs). CD11c can bind complement iC3b and mediate phagocytosis in vitro, for which it is also referred to as complement receptor 4. However, the functions of this prominent marker protein in DCs, especially in vivo, remain poorly defined. Here, in the process of studying DC activation and immune responses induced by cells lacking self-CD47, we found that DC capture of CD47-deficient cells and DC activation was dependent on the integrin-signaling adaptor Talin1. Specifically, CD11c and its partner Itgb2 were required for DC capture of CD47-deficient cells. CD11b was not necessary for this process but could partially compensate in the absence of CD11c. Mice with DCs lacking Talin1, Itgb2, or CD11c were defective in supporting T-cell proliferation and differentiation induced by CD47-deficient cell associated antigen. These findings establish a critical role for CD11c in DC antigen uptake and activation in vivo. They may also contribute to understanding the functional mechanism of CD47-blockade therapies.

Recruitment of foamy monocytes to inflamed endothelium expressing VCAM-1 contributes to the development of plaque during atherogenesis. Foamy CD11c+ monocytes arise in the circulation during the onset of hypercholesterolemia and recruit to nascent plaque, but the mechanism of CD11c/CD18 and very late Ag-4 (VLA-4) activation and cooperation in shear-resistant cell arrest on VCAM-1 are ill defined. Within 1 wk of the onset of a Western high-fat diet (WD) in apolipoprotein E–deficient mice, an inflammatory subset of foamy monocytes emerged that made up one fourth of the circulating population. These cells expressed ∼3-fold more CD11c/CD18 and 50% higher chemokine receptors than nonfoamy monocytes. Recruitment from blood to a VCAM-1 substrate under shear stress was assessed ex vivo using a unique artery-on-a-chip microfluidic assay. It revealed that foamy monocytes from mice on a WD increased their adhesiveness over 5 wk, rising to twice that of mice on a normal diet or CD11c−/− mice fed a WD. Shear-resistant capture of foamy human or mouse monocytes was initiated by high-affinity CD11c, which directly activated VLA-4 adhesion via phosphorylated spleen tyrosine kinase and paxillin within focal adhesion complexes. Lipid uptake and activation of CD11c are early and critical events in signaling VLA-4 adhesive function on foamy monocytes competent to recruit to VCAM-1 on inflamed arterial endothelium.

Background Hypertriglyceridemia increases risk for atherosclerotic cardiovascular disease and may contribute to atherosclerosis by changing circulating monocyte phenotypes. High-dose n-3 polyunsaturated fatty acids reduce blood triglyceride levels. Effects of triglyceride-lowering therapy on monocyte phenotypes are not well known. Objective We examined effects of n-3 polyunsaturated fatty acid treatments (eicosapentaenoic acid [EPA] plus docosapentaenoic acid [MAT9001] vs EPA ethyl esters [EPA-EE]) on monocyte phenotypes in individuals with hypertriglyceridemia. Methods Individuals with triglycerides 200 to 400 mg/dL were recruited. Subjects received 2 treatments in randomized order for 14 days each: MAT9001 and EPA-EE, at 4 g/d. At 2 days before the start of, and on the last day of, each treatment, nile red staining for lipids and phenotypes of each monocyte subset were examined by flow cytometry after an overnight fast and postprandially after a high-fat meal. Results Treatment with MAT9001 or EPA-EE reduced fasting triglyceride levels and decreased proportions of intermediate monocytes. Only MAT9001 decreased postprandial blood triglyceride levels, lowered fasting nile red levels, indicating less lipid in classical and intermediate monocytes, and reduced postprandial CD11c levels on nonclassical monocytes. MAT9001 and EPA-EE each reduced fasting and postprandial CD11c and CD36 levels on classical and intermediate monocytes and postprandial CCR5 levels on intermediate and nonclassical monocytes, with no significant differences between the 2 treatments. Conclusions Treatment with MAT9001 in individuals with hypertriglyceridemia reduced fasting nile red staining for lipids in classical and intermediate monocytes. MAT9001 and EPA-EE each improved fasting and postprandial monocyte phenotypes, which could potentially help to protect against atherosclerosis.

Macrophage accumulation is a critical step during development of chronic inflammation, initiating progression of many devastating diseases. Leukocyte-specific integrin αDβ2 (CD11d/CD18) is dramatically upregulated on macrophages at inflammatory sites. Previously we found that CD11d overexpression on cell surfaces inhibits in vitro cell migration due to excessive adhesion. In this study, we have investigated how inflammation-mediated CD11d upregulation contributes to macrophage retention at inflammatory sites during atherogenesis. Atherosclerosis was evaluated in CD11d−/−/ApoE−/− mice after 16 wk on a Western diet. CD11d deficiency led to a marked reduction in lipid deposition in aortas and isolated macrophages. Macrophage numbers in aortic sinuses of CD11d−/− mice were reduced without affecting their apoptosis and proliferation. Adoptive transfer of fluorescently labeled wild-type and CD11d−/− monocytes into ApoE−/− mice demonstrated similar recruitment from circulation, but reduced accumulation of CD11d−/− macrophages within the aortas. Furthermore, CD11d expression was significantly upregulated on macrophages in atherosclerotic lesions and M1 macrophages in vitro. Interestingly, expression of the related ligand-sharing integrin CD11b was not altered. This difference defines their distinct roles in the regulation of macrophage migration. CD11d-deficient M1 macrophages demonstrated improved migration in a three-dimensional fibrin matrix and during resolution of peritoneal inflammation, whereas migration of CD11b−/− M1 macrophages was not affected. These results prove the contribution of high densities of CD11d to macrophage arrest during atherogenesis. Because high expression of CD11d was detected in several inflammation-dependent diseases, we suggest that CD11d/CD18 upregulation on proinflammatory macrophages may represent a common mechanism for macrophage retention at inflammatory sites, thereby promoting chronic inflammation and disease development.

A large randomized clinical trial (PREDIMED) showed that adding “healthy monounsaturated fat (MUF)” to Mediterranean diet (MedD) by supplementation with extra virgin olive oil or nuts led to a reduction in atherosclerotic cardiovascular events, but the mechanisms remain incompletely understood. Hyperlipidemia, a major risk factor for atherosclerosis, may induce lipid accumulation in circulating monocytes, leading to formation of foamy monocytes (FMs), which contribute to atherosclerosis. We hypothesize that high-MUF MedD reduces FM formation and therefore inhibits atherogenesis associated with hyperlipidemia. To test this, LDLR-/- mice were fed western-type high-saturated fat, high-cholesterol diet (WD) (21% milkfat containing 13.3% saturated fat and 5.9% MUF; 0.2% cholesterol), high-MUF MedD with high cholesterol (HC-MedD, 21% fat [from extra-virgin olive oil, walnuts, almonds, and hazelnuts] containing 2.6% saturated fat and 13.4% MUF; 0.2% cholesterol), or normal diet (ND, control). At 3 months, mice on HC-MedD had similar body weight gain but significantly lower liver/body weight index compared to mice on WD. Plasma triglyceride levels were significantly lower in mice on HC-MedD (318 ± 31 mg/dL, n=13) than on WD (769 ± 60 mg/dL, n=9, P

High-fat diet (HFD) feeding in mice is characterized by accumulation of αβ T cells in adipose tissue. However, the contribution of αβ T cells to obesity-induced inflammation of skeletal muscle, a major organ of glucose uptake, is unknown. This study was undertaken to evaluate the effect of αβ T cells on insulin sensitivity and inflammatory state of skeletal muscle and adipose tissue in obesity. Furthermore, we investigated whether CD4+IFNγ+ (TH1) cells are involved in skeletal muscle and adipose tissue metabolic dysfunction that accompanies obesity.Mice lacking αβ T cells (T cell receptor beta chain-deficient [TCRb-/-] mice) were fed HFD for 12 weeks. Obesity-induced skeletal muscle and adipose tissue inflammation was assessed by flow cytometry and quantitative RT-PCR. To investigate the effect of TH1 cells on skeletal muscle and adipose tissue inflammation and metabolic functions, we injected 5×10(5) TH1 cells or PBS weekly over 12 weeks into HFD-fed TCRb-/- mice. We also cultured C2C12 myofibers and 3T3-L1 adipocytes with TH1-conditioned medium.We showed that similar to adipose tissue, skeletal muscle of obese mice have higher αβ T cell content, including TH1 cells. TCRb-/- mice were protected against obesity-induced hyperglycemia and insulin resistance. We also demonstrated suppressed macrophage infiltration and reduced inflammatory cytokine expression in skeletal muscle and adipose tissue of TCRb-/- mice on HFD compared to wild-type obese controls. Adoptive transfer of TH1 cells into HFD-fed TCRb-/- mice resulted in increased skeletal muscle and adipose tissue inflammation and impaired glucose metabolism. TH1 cells directly impaired functions of C2C12 myotubes and 3T3-L1 adipocytes in vitro.We conclude that reduced adipose tissue and skeletal muscle inflammation in obese TCRb-/- mice is partially attributable to the absence of TH1 cells. Our results suggest an important role of TH1 cells in regulating inflammation and insulin resistance in obesity.

Intake of western diet (WD) high in saturated fat and cholesterol causes formation of foamy monocytes (FMs; monocytes containing intracellular lipid droplets) in the circulation, which contribute to atherogenesis, in apoE-/- mice. It remains to be determined which diet component, fat or cholesterol, is more important in inducing FM formation. Mediterranean-type diet (MedD) high in monounsaturated fat (MUF) protects against atherosclerotic events. It is unknown whether MedD affects FM formation. To address these questions, 4 groups of apoE-/- mice were randomly assigned to the following diets: 1) WD (21% w/w milkfat containing 13.3% saturated fat and 5.9% MUF; 0.2% w/w cholesterol); 2) high-fat low-cholesterol diet (HFD, 21% milkfat; 0.05% cholesterol); 3) high-cholesterol low-fat diet (HCD, 5% milkfat; 0.2% cholesterol); 4) MedD with high cholesterol (21% fat containing 2.6% saturated fat and 13.4% MUF from 15% extra-virgin olive oil, 3% walnut fat, 1.5% almond fat and 1.5% hazelnut fat; 0.2% cholesterol). FMs and phenotypes were examined by flow cytometry. Calorie intake and weight changes were not different among the 4 groups of mice. At 1 week on diets, mice on WD or HCD, but not mice on HFD, had abundant FMs in the circulation (Table). Compared to mice on WD or HCD, mice on MedD had lower proportions of FMs and lower side scatter (SSC) values, indicating less lipid, in FMs. Mean fluorescence intensity of CD36, a scavenger receptor, tended to be lower on FMs in mice on MedD than in mice on WD. At 8 weeks, mice on HFD also had abundant FMs, which were, however, still lower than those in mice on WD. Compared to those in mice on WD, the percentage and SSC values of FMs remained lower in mice on MedD for 8 weeks (Table). In summary, high cholesterol appears to be the major dietary component that induces early FM formation in apoE-/- mice while persistent intake of high saturated fat also induces FM formation. Fewer FMs in mice on MedD than on WD or HCD suggests that MUF in MedD may inhibit FM formation.

Background and objective: Fasting and postprandial (PP) hypertriglyceridemia is associated with increased lipid accumulation in circulating monocytes and monocyte phenotypic changes, e.g., increased expression of CD11c (a β2 integrin), which may increase risk for atherosclerosis. Omega-3 fatty acids lower circulating triglycerides (TG). This study examined whether treatment with omega-3 fatty acids improves fasting and PP monocyte phenotypes associated with hypertriglyceridemia. Methods: This was an open-label, randomized, crossover study of men and women with elevated TG (200-400 mg/dL) to evaluate the effects of MAT9001 (eicosapentaenoic acid [EPA] plus docosapentaenoic acid [DPA], Matinas BioPharma Inc., USA), compared to Vascepa (EPA-ethyl esters [EE] only, Amarin Pharma Inc., USA), administered at 4 g/d dosages for 15 d (≥28-d washout between treatments). Fasting and PP (4 and 6 h) TG and monocyte phenotypes (analyzed by flow cytometry) were examined prior to and on d 15 of each treatment. Results: MAT9001 and Vascepa lowered fasting TG from baseline (-32% and -19% respectively; both p≤0.04; n=26-29). Only MAT9001 significantly reduced PP TG area under the curve (AUC) from pre- to post-treatment (p Summary: Decreases in TG produced by MAT9001 or Vascepa in men and women with hypertriglyceridemia were associated with reduced fasting and PP CD11c on cM and iM. MAT9001, but not Vascepa, significantly reduced PP ncM CD11c and fasting cM and iM nile red staining for lipids.

Objective To identify the role of triglyceride-rich lipoproteins (TGRLs) and apoE, a major apolipoprotein in TGRLs, in adipose tissue inflammation with high-fat diet (HFD)-induced obesity. Methods Male apoE −/− and C57BL/6J wild-type (WT) mice fed HFD for 12 weeks were assessed for metabolic and inflammatory parameters. ApoE −/− and WT mice were orally gavaged with [ 3 H]palmitic acid to examine the role of apoE in fat delivery to adipose tissue. VLDL from obese apoE −/− mice were intravenously injected into lean WT or apoE −/− mice to test potential contribution of TGRLs-derived fat delivery to inflammation in adipose tissue and the role of apoE. Results ApoE −/− mice gained less body weight, and had less fat mass and lower triglyceride levels in skeletal muscle than WT. ApoE −/− mice on HFD had better insulin sensitivity than WT even when comparing body weight-matched mice. Compared to WT mice, apoE −/− mice on HFD had lower levels of inflammatory cytokines/chemokines and CD11c in adipose tissue, and lower levels of inflammatory markers in skeletal muscle. At 6 h after oral gavage with [ 3 H]palmitic acid, incorporation of [ 3 H]palmitic acid into adipose tissue and skeletal muscle was lower in apoE −/− mice. After repeated daily injection for 3 days, VLDL from obese apoE −/− mice induced inflammation in adipose tissue of recipient WT but not apoE −/− mice. Conclusion In HFD-induced obesity, apoE plays an important role in inflammation in adipose tissue and skeletal muscle, likely by mediating TGRL-derived fat delivery to these tissues.

Accumulation of foam cells — macrophages with intracellular lipid droplets — in arterial walls is a hallmark of atherosclerosis. Bernelot Moens and colleagues report increases in circulating monocytes with intracellular lipid accumulation, associated CCR2 expression, and enhanced monocyte migration in patients with familial hypercholesterolaemia. These changes could be reversed by PCSK9-inhibitor treatment.

We studied the effects of weight loss induced by either a low-fat normal diet (ND) or restriction of high-fat diet (HFD) on hepatic steatosis, inflammation in the liver and adipose tissue (AT), and blood monocytes of obese mice.In mice with HFD-induced obesity, weight loss was achieved by switching from HFD to ND and maintaining on ND ad libitum or by restricting HFD intake to match body weight of mice with ND-induced weight loss. After diet interventions for 4 weeks, hepatic steatosis, hepatic and AT inflammation, and blood CD11c(+) monocytes were examined.At 4 weeks after switching diets, body weight was reduced by 23% from baseline. To achieve the same reduced body weight required restricting calorie intake from HFD. Weight loss with either ND or HFD restriction decreased body fat mass and ameliorated liver steatosis; both effects were greater with ND-induced weight loss than HFD restriction-induced weight loss. Weight loss with ND but not HFD restriction normalized blood CD11c(+) monocytes and attenuated hepatic inflammation assessed by chemokine and CD11c expression. In contrast, weight loss with HFD restriction significantly reduced chemokine levels and CD11c(+) cells in AT compared to obese controls, and tended to reduce AT chemokines and CD11c(+) cells more than ND-induced weight loss.In mice with diet-induced obesity, weight loss with ND was superior in alleviating hepatic inflammation and steatosis, whereas weight loss with HFD calorie restriction provided greater amelioration of AT inflammation.

Objective— Atherosclerosis is associated with monocyte adhesion to the arterial wall that involves integrin activation and emigration across inflamed endothelium. Involvement of β 2 -integrin CD11c/CD18 in atherogenesis was recently shown in dyslipidemic mice, which motivates our study of its inflammatory function during hypertriglyceridemia in humans. Methods and Results— Flow cytometry of blood from healthy subjects fed a standardized high-fat meal revealed that at 3.5 hours postprandial, monocyte CD11c surface expression was elevated, and the extent of upregulation correlated with blood triglycerides. Monocytes from postprandial blood exhibited an increased light scatter profile, which correlated with elevated CD11c expression and uptake of lipid particles. Purified monocytes internalized triglyceride-rich lipoproteins isolated from postprandial blood through low-density lipoprotein–receptor–related protein-1, and this also elicited CD11c upregulation. Laboratory-on-a-chip analysis of whole blood showed that monocyte arrest on a vascular cell adhesion molecule-1 (VCAM-1) substrate under shear flow was elevated at 3.5 hours and correlated with blood triglyceride and CD11c expression. At 7 hours postprandial, blood triglycerides decreased and monocyte CD11c expression and arrest on VCAM-1 returned to fasting levels. Conclusion— During hypertriglyceridemia, monocytes internalize lipids, upregulate CD11c, and increase adhesion to VCAM-1. These data suggest that analysis of monocyte inflammation may provide an additional framework for evaluating individual susceptibility to cardiovascular disease.

Background— Obesity is associated with chronic inflammation, which includes increased macrophage accumulation in adipose tissue (AT) and upregulation of chemokines and cytokines. T cells also play important roles in chronic inflammatory diseases such as atherosclerosis but have not been well studied in obesity. Methods and Results— Flow cytometric analysis showed higher numbers of T cells and macrophages in AT of diet-induced obese insulin-resistant male mice than in lean mice and obese females ( P Conclusions— Obesity is associated with increased accumulation of T cells and macrophages in AT, which may play important roles in obesity-related disease by influencing preadipocyte/adipocyte functions. RANTES is an adipokine that is upregulated in AT by obesity in both mice and humans.

Objective— To examine infiltration of blood foamy monocytes, containing intracellular lipid droplets, into early atherosclerotic lesions and its contribution to development of nascent atherosclerosis. Approach and Results— In apoE –/– mice fed Western high-fat diet (WD), >10% of circulating monocytes became foamy monocytes at 3 days on WD and >20% of monocytes at 1 week. Foamy monocytes also formed early in blood of Ldlr –/– Apobec1 –/– (LDb) mice on WD. Based on CD11c and CD36, mouse monocytes were categorized as CD11c – CD36 – , CD11c – CD36 + , and CD11c + CD36 + . The majority of foamy monocytes were CD11c + CD36 + , whereas most nonfoamy monocytes were CD11c – CD36 – or CD11c – CD36 + in apoE –/– mice on WD. In wild-type mice, CD11c + CD36 + and CD11c – CD36 + , but few CD11c – CD36 – , monocytes took up cholesteryl ester–rich very low-density lipoproteins (CE-VLDLs) isolated from apoE –/– mice on WD, and CE-VLDL uptake accelerated CD11c – CD36 + to CD11c + CD36 + monocyte differentiation. Ablation of CD36 decreased monocyte uptake of CE-VLDLs. Intravenous injection of DiI-CE-VLDLs in apoE –/– mice on WD specifically labeled CD11c + CD36 + foamy monocytes, which infiltrated into nascent atherosclerotic lesions and became CD11c + cells that were selectively localized in atherosclerotic lesions. CD11c deficiency reduced foamy monocyte infiltration into atherosclerotic lesions. Specific and consistent depletion of foamy monocytes (for 3 weeks) by daily intravenous injections of low-dose clodrosome reduced development of nascent atherosclerosis. Conclusions— Foamy monocytes, which form early in blood of mice with hypercholesterolemia, infiltrate into early atherosclerotic lesions in a CD11c-dependent manner and play crucial roles in nascent atherosclerosis development.

Signal Transducer and Activator of Transcription ( Stat2 ) is a transcription factor that plays a critical role in type I interferon (IFN) signaling. Recent evidence supports a role for the type I IFN pathway in atherosclerosis, since recombinant IFN alpha and IFN beta both promote atherosclerosis in mice. We tested the hypothesis that constitutive type I IFN signaling through STAT2 may promote atherosclerotic lesion formation. Male Ldlr KO and Stat2/Ldlr DKO mice on a C57BL6/J background were fed a western diet for 16 weeks. Total cholesterol levels were indistinguishable at baseline ( Ldlr KO: 232 ± 24 vs. Stat2/Ldlr DKO: 239 ± 36 mg/dl, p=0.39), but significantly higher in the Stat2/Ldlr DKO mice after 16 weeks of western diet ( Ldlr KO: 856 ± 203 Vs Stat2/Ldlr DKO: 1015 ± 176 mg/dl, p=0.004). Despite consuming less food than Ldlr KO controls, the Stat2/Ldlr DKO animals weighed significantly more than controls and had greater fat mass in the inguinal subcutaneous and perigonadal depots respectively ( Ldlr KO: 0.45±0.23 Vs Stat2/Ldlr DKO: 0.69 ± 0.27 g, p=0.003 and Ldlr KO: 0.89 ± 0.50 Vs Stat2/Ldlr DKO: 1.39 ± 0.56 g, p=0.003). Surprisingly, no significant differences were observed in percent lesional area of aortae ( Ldlr KO: 9.7% ± 5.6% Vs Stat2/Ldlr DKO: 12.5% ± 6.8%, p=0.156). In conclusion, STAT2 does not appear to have a major impact on atherosclerosis in the absence of exogenous type I IFNs or other agonism of the pathway.