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Objectives The co-stimulatory CD40L–CD40 dyad exerts a critical role in atherosclerosis by modulating leukocyte accumulation into developing atherosclerotic plaques. The requirement for cell-type specific expression of both molecules, however, remains elusive. Here, we evaluate the contribution of CD40 expressed on endothelial cells (ECs) in a mouse model of atherosclerosis. Methods and Results Atherosclerotic plaques of apolipoprotein E-deficient (Apoe −/− ) mice and humans displayed increased expression of CD40 on ECs compared with controls. To interrogate the role of CD40 on ECs in atherosclerosis, we induced EC-specific (BmxCreERT2-driven) deficiency of CD40 in Apoe −/− mice. After feeding a chow diet for 25 weeks, EC-specific deletion of CD40 (iEC-CD40) ameliorated plaque lipid deposition and lesional macrophage accumulation but increased intimal smooth muscle cell and collagen content, while atherosclerotic lesion size did not change. Leukocyte adhesion to the vessel wall was impaired in iEC-CD40-deficient mice as demonstrated by intravital microscopy. In accord, expression of vascular cell adhesion molecule 1 (VCAM-1) and intercellular adhesion molecule 1 (ICAM-1) in the vascular endothelium declined after deletion of CD40. In vitro, antibody-mediated inhibition of human endothelial CD40 significantly abated monocyte adhesion on ECs. Conclusion Endothelial deficiency of CD40 in mice promotes structural features associated with a stable plaque phenotype in humans and decreases leukocyte adhesion. These results suggest that endothelial-expressed CD40 contributes to inflammatory cell migration and consecutive plaque formation in atherogenesis.

Statins induce plaque regression characterized by reduced macrophage content in humans, but the underlying mechanisms remain speculative. Studying the translational APOE*3-Leiden.CETP mouse model with a humanized lipoprotein metabolism, we find that systemic cholesterol lowering by oral atorvastatin or dietary restriction inhibits monocyte infiltration, and reverses macrophage accumulation in atherosclerotic plaques. Contrary to current believes, none of (1) reduced monocyte influx (studied by cell fate mapping in thorax-shielded irradiation bone marrow chimeras), (2) enhanced macrophage egress (studied by fluorescent bead labeling and transfer), or (3) atorvastatin accumulation in murine or human plaque (assessed by mass spectrometry) could adequately account for the observed loss in macrophage content in plaques that undergo phenotypic regression. Instead, suppression of local proliferation of macrophages dominates phenotypic plaque regression in response to cholesterol lowering: the lower the levels of serum LDL-cholesterol and lipid contents in murine aortic and human carotid artery plaques, the lower the rates of in situ macrophage proliferation. Our study identifies macrophage proliferation as the predominant turnover determinant and an attractive target for inducing plaque regression. Supplementary Information The online version contains supplementary material available at 10.1007/s00395-020-00838-4.

In einer grosen Anzahl wissenschaftlicher Publikationen des letzten Jahrzehnts wurde die Inflammation als wesentlicher Kausalfaktor des Diabetes mellitus und der Atherosklerose identifiziert. Im Vergleich zum nicht an Diabetes leidenden Patienten fuhrt der durch Hyperglykamie und Insulinresistenz/-defizienz gekennzeichnete Diabetes mellitus zu einer verstarkten Aktivierung inflammatorischer Zytokine und Zellen und damit einer beschleunigten Atherosklerose. In dieser Ubersichtsarbeit werden die wesentlichen Faktoren der diabetesassoziierten Inflammation beschrieben. Im Weiteren wird auf mogliche antiinflammatorische Therapieansatze eingegangen, die moglicherweise das Risiko der diabetischen Makroangiopathie vermindern konnen. Die multifaktorielle Therapie des Diabetes mellitus konnte in Zukunft neben Blutzucker- und Cholesterinspiegel- sowie Bluthochdruckkontrolle durch eine antientzundliche Therapie erganzt werden.

Diabetes worsens atherosclerosis progression and leads to a defect in repair of arteries after cholesterol reduction, a process termed regression. Empagliflozin reduces blood glucose levels via inhibition of the sodium glucose cotransporter 2 (SGLT-2) in the kidney and has been shown to lead to a marked reduction in cardiovascular events in humans. To determine whether glucose lowering by empagliflozin accelerates atherosclerosis regression in a mouse model, male C57BL/6J mice were treated intraperitoneally with LDLR- and SRB1- antisense oligonucleotides and fed a high cholesterol diet for 16 weeks to induce severe hypercholesterolemia and atherosclerosis progression. At week 14 all mice were rendered diabetic by streptozotocin (STZ) injections. At week 16 a baseline group was sacrificed and displayed substantial atherosclerosis of the aortic root. In the remaining mice, plasma cholesterol was lowered by switching to chow diet and treatment with LDLR sense oligonucleotides to induce atherosclerosis regression. These mice then received either empagliflozin or vehicle for three weeks. Atherosclerotic plaques in the empagliflozin treated mice were significantly smaller, showed decreased lipid and CD68+ macrophage content, as well as greater collagen content. Proliferation of plaque resident macrophages and leukocyte adhesion to the vascular wall were significantly decreased in empagliflozin-treated mice. In summary, plasma glucose lowering by empagliflozin improves plaque regression in diabetic mice.

Introduction Many clinical and experimental observations have established an association between visceral obesity and chronic adipose tissue inflammation. Potent pro-inflammatory mediators such as TNFα, CD40 and IL-1β are regulated by Tumor necrosis factor (TNF) receptor-associated factors (TRAFs). TRAF5 deficiency accelerates atherogenesis in mice by increasing inflammatory leukocyte recruitment. Since inflammatory cell invasion is also a prerequisite of adipose tissue inflammation, we tested the hypothesis that deficient TRAF5 signaling aggravates adipose tissue inflammation and its metabolic complications in a murine diet-induced obesity (DIO) model. Purpose We aimed to clarify the role of TRAF5 in adipose tissue inflammation and metabolic syndrome. Methods TRAF5−/− mice and gender- and age-matched wild-type (WT) mice consumed a high fat diet (HFD, 45%kcal from fat) or a matched low-fat diet (LFD, 10%kcal from fat) for 18 weeks to induce DIO and adipose tissue inflammation. All mice were then subjected to subsequent analysis, including glucose and insulin tolerance testing, body composition assessment by MRI imaging, flow cytometry, gene expression of different tissues, plasma analysis and histology. Finally, we studied if TRAF5 expression was associated with metabolic syndrome in humans by analyzing plasma and adipocytes samples from 62 patients of the Tumor-Necrosis-Factor Receptor Associated in Cardiovascular Risk Study (TRAFICS). Results TRAF5 expression was significantly attenuated in isolated WT-adipocytes and WT-macrophages after 18 weeks of HFD compared to LFD-fed controls. TRAF5−/− mice on HFD gained significantly more weight compared to TRAF5-competent mice and showed an aggravated metabolic phenotype, including impaired insulin tolerance, hyperinsulinemia and increased fasting glucose plasma levels. The weight gain in TRAF5−/− mice was attributable to a significant increase in adipose tissue and liver weight. Further analysis of the visceral adipose tissue revealed enhanced macrophage accumulation and increased pro-inflammatory CD11c+ subset polarization in HFD-fed TRAF5−/− mice. In line with an increased migratory capacity of inflammatory cells, we observed enhanced peritoneal invasion of leukocytes and subsets in TRAF5−/− mice. Accordingly, TRAF5 deficiency increased inflammatory cytokine expression and ameliorated parameters of insulin sensitivity in adipose tissue. Finally, patients with metabolic syndrome displayed decreased TRAF5 expression in blood and adipocytes compared to humans without metabolic syndrome. Conclusion We show that genetic deficiency of TRAF5 aggravates metabolic syndrome in murine diet-induced obesity. Enhanced accumulation of leukocytes subsets in adipose tissue serves as the likely mechanism. We conclude that TRAF5 signaling properties may favorably affect metabolic disease. Acknowledgement/Funding Forschungskommission Medizinische Fakultät Universität Freiburg, MOTI-VATE Promotionskolleg der Medizinischen Fakultät Freiburg (EKFS)

Background Inflammation drives atherosclerosis and its complications. Anti-inflammatory therapy with interleukin 1 beta (IL-1β) antibody reduces cardiovascular events in patients with elevated high-sensitive C-reactive protein (hsCRP). This study aims to identify the share of patients with coronary heart disease (CHD) and residual inflammation who may benefit from anti-inflammatory therapy. Methods hsCRP and low-density lipoprotein (LDL) levels were determined in 2741 all-comers admitted to the cardiological ward of our tertiary referral hospital between June 2016 and June 2018. Patients without CHD, with acute coronary syndrome, chronic or recurrent systemic infection, use of immunosuppressant or anti-inflammatory agents, chronic inflammatory diseases, chemotherapy, terminal organ failure, traumatic injury and pregnancy were excluded. Results 856 patients with stable CHD were included. 42.7% of those had elevated hsCRP ≥ 2 mg/l. Within the group of patients with LDL-cholesterol

Sterile inflammation of visceral fat, provoked by dying adipocytes, links the metabolic syndrome to cardiovascular disease. Danger-associated molecular patterns, such as adenosine triphosphate (ATP), are released by activated or dying cells and orchestrate leukocyte infiltration and inflammation via the purinergic receptor P2Y2. The gene expression of ATP receptor P2Y2 did not change in several tissues in the course of obesity, but was increased within epididymal fat. Adipose tissue from P2Y 2 −/− mice consuming high-fat diet (HFD) contained less crown-like structures with a reduced frequency of adipose tissue macrophages (ATMs). This was likely due to decreased leukocyte migration because of missing VCAM-1 exposition on P2Y2 deficient hypertrophic adipose tissue endothelial cells. Accordingly, P2Y 2 −/− mice showed blunted traits of the metabolic syndrome: they gained less weight compared to P2Y 2 +/+ controls, while intake of food and movement behaviour remained unchanged. Liver and adipose tissue were smaller in P2Y 2 −/− animals. Insulin tolerance testing (ITT) performed in obese P2Y 2 −/− mice revealed a better insulin sensitivity as well as lower plasma C-peptide and cholesterol levels. We demonstrate that interfering with somatic P2Y2 signalling prevents excessive immune cell deposition in diet-induced obesity (DIO), both attenuating adipose tissue inflammation and ameliorating the metabolic phenotype. Thus, blocking the P2Y2 cascade may be a promising strategy to limit metabolic disease and its sequelae.

Rationale: The coincidence of inflammation and metabolic derangements in obese adipose tissue has sparked the concept of met-inflammation. Previous observations, however, suggest that inflammatory pathways may not ultimately cause dysmetabolism. Objective: We have revisited the relationship between inflammation and metabolism by testing the role of TRAF (tumor necrosis receptor-associated factor)-1, an inhibitory adapter of inflammatory signaling of TNF (tumor necrosis factor)-a, IL (interleukin)-1ß, and TLRs (toll-like receptors). Methods and Results: Mice defcient for TRAF-1, which is expressed in obese adipocytes and adipose tissue lymphocytes, caused an expected hyperinflammatory phenotype in adipose tissue with enhanced adipokine and chemokine expression, increased leukocyte accumulation, and potentiated proinflammatory signaling in macrophages and adipocytes in a mouse model of diet-induced obesity. Unexpectedly, TRAF-1-/-mice were protected from metabolic derangements and adipocyte growth, failed to gain weight, and showed improved insulin resistance-an effect caused by increased lipid breakdown in adipocytes and UCP (uncoupling protein)-1-enabled thermogenesis. TRAF-1-dependent catabolic and proinflammatory cues were synergistically driven by ß3-adrenergic and inflammatory signaling and required the presence of both TRAF-1-defcient adipocytes and macrophages. In human obesity, TRAF-1-dependent genes were upregulated. Conclusions: Enhancing TRAF-1-dependent inflammatory pathways in a gain-of-function approach protected from metabolic derangements in diet-induced obesity. These fndings identify TRAF-1 as a regulator of dysmetabolism in mice and humans and question the pathogenic role of chronic inflammation in metabolism. Fil: Michel, Nathaly Anto. University of Freiburg. University Medical Center; Alemania Fil: Colberg, Christian. University of Freiburg. University Medical Center; Alemania Fil: Buscher, Konrad. La Jolla Institute for Allergy and Immunology; Estados Unidos Fil: Sommer, Björn. Universitat Erlangen-Nuremberg; Alemania Fil: Pramod, Akula Bala. La Jolla Institute for Allergy and Immunology; Estados Unidos Fil: Ehinger, Erik. La Jolla Institute for Allergy and Immunology; Estados Unidos Fil: Dufner, Bianca. University of Freiburg. University Medical Center; Alemania Fil: Hoppe, Natalie. University of Freiburg. University Medical Center; Alemania Fil: Pfeiffer, Katharina. University of Freiburg. University Medical Center; Alemania Fil: Marchini, Timoteo Oscar. University of Freiburg. University Medical Center; Alemania. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Houssay. Instituto de Bioquímica y Medicina Molecular. Universidad de Buenos Aires. Facultad Medicina. Instituto de Bioquímica y Medicina Molecular; Argentina Fil: Willecke, Florian. University of Freiburg. University Medical Center; Alemania Fil: Stachon, Peter. University of Freiburg. University Medical Center; Alemania Fil: Hilgendorf, Ingo. University of Freiburg. University Medical Center; Alemania Fil: Heidt, Timo. University of Freiburg. University Medical Center; Alemania Fil: Von Zur Muhlen, Constantin. University of Freiburg. University Medical Center; Alemania Fil: Von Elverfeldt, Dominik. University of Freiburg. University Medical Center; Alemania Fil: Pfeifer, Dietmar. University of Freiburg; Alemania Fil: Schüle, Roland. University of Freiburg; Alemania Fil: Kintscher, Ulrich. University of Freiburg; Alemania Fil: Brachs, Sebastian. Center For Cardiovascular Research; Alemania Fil: Ley, Klaus. La Jolla Institute for Allergy and Immunology; Estados Unidos Fil: Bode, Christoph. University of Freiburg. University Medical Center; Alemania Fil: Zirlik, Andreas. University of Freiburg. University Medical Center; Alemania Fil: Wolf, Dennis. La Jolla Institute for Allergy and Immunology; Estados Unidos

Movement of circulating fatty acids (FAs) to parenchymal cells requires their transfer across the endothelial cell (EC) barrier. The multiligand receptor cluster of differentiation 36 (CD36) facilitates tissue FA uptake and is expressed in ECs and parenchymal cells such as myocytes and adipocytes. Whether tissue uptake of FAs is dependent on EC or parenchymal cell CD36, or both, is unknown. Using a cell-specific deletion approach, we show that EC, but not parenchymal cell, CD36 deletion increased fasting plasma FAs and postprandial triglycerides. EC-Cd36-KO mice had reduced uptake of radiolabeled long-chain FAs into heart, skeletal muscle, and brown adipose tissue; these uptake studies were replicated using [11C]palmitate PET scans. High-fat diet-fed EC-CD36-deficient mice had improved glucose tolerance and insulin sensitivity. Both EC and cardiomyocyte (CM) deletion of CD36 reduced heart lipid droplet accumulation after fasting, but CM deletion did not affect heart glucose or FA uptake. Expression in the heart of several genes modulating glucose metabolism and insulin action increased with EC-CD36 deletion but decreased with CM deletion. In conclusion, EC CD36 acts as a gatekeeper for parenchymal cell FA uptake, with important downstream effects on glucose utilization and insulin action.

Rationale: Animal models have been used to explore factors that regulate atherosclerosis. More recently, they have been used to study the factors that promote loss of macrophages and reduction in lesion size after lowering of plasma cholesterol levels. However, current animal models of atherosclerosis regression require challenging surgeries, time-consuming breeding strategies, and methods that block liver lipoprotein secretion. Objective: We sought to develop a more direct or time-effective method to create and then reverse hypercholesterolemia and atherosclerosis via transient knockdown of the hepatic LDLR (low-density lipoprotein receptor) followed by its rapid restoration. Methods and Results: We used antisense oligonucleotides directed to LDLR mRNA to create hypercholesterolemia in wild-type C57BL/6 mice fed an atherogenic diet. This led to the development of lesions in the aortic root, aortic arch, and brachiocephalic artery. Use of a sense oligonucleotide replicating the targeted sequence region of the LDLR mRNA rapidly reduced circulating cholesterol levels because of recovery of hepatic LDLR expression. This led to a decrease in macrophages within the aortic root plaques and brachiocephalic artery, that is, regression of inflammatory cell content, after a period of 2 to 3 weeks. Conclusions: We have developed an inducible and reversible hepatic LDLR knockdown mouse model of atherosclerosis regression. Although cholesterol reduction decreased early en face lesions in the aortic arches, macrophage area was reduced in both early and late lesions within the aortic sinus after reversal of hypercholesterolemia. Our model circumvents many of the challenges associated with current mouse models of regression. The use of this technology will potentially expedite studies of atherosclerosis and regression without use of mice with genetic defects in lipid metabolism.

SummaryCD40L figures prominently in atherogenesis. Recent data demonstrate elevated levels of sCD40L in the serum of patients with the metabolic syndrome (MS). This study investigated the role of CD40L in pro-inflammatory gene expression and cellular differentiation in adipose tissue to obtain insight into mechanisms linking the MS with atherosclerosis. Human adipocytes and preadipocytes expressed CD40 but not CD40L. Stimulation with recombinant CD40L or membranes over-expressing CD40L induced a time- and dose-dependent expression of IL-6, MCP-1, IL-8, and PAI-1. Supernatants of CD40L-stimulated adipose cells activated endothelial cells, suggesting a systemic functional relevance of our findings. Neutralising antibodies against CD40L attenuated these effects substantially. Signalling studies revealed the involvement of mitogen-activated protein kinases and NFκB. Furthermore, stimulation with CD40L resulted in enhanced activation of C/EBPα and PPARγ and promoted adipogenesis of preadipose cells in the presence and absence of standard adipogenic conditions. Finally, patients suffering from the metabolic syndrome with high levels of sCD40L also displayed high levels of IL-6, in line with the concept that CD40L may induce the expression of inflammatory cytokines in vivo in this population. Our data reveal potent metabolic functions of CD40L aside from its known pivotal pro-inflammatory role within plaques. Our data suggest that CD40L may mediate risk at the interface of metabolic and atherothrombotic disease.

SummaryPlasminogen activator inhibitor type-1 (PAI-1), an established marker and mediator of cardiovascular risk, is produced extensively in adipose tissue. Fibrates are hypolipidemic peroxisome proliferator activated receptor-alpha (PPARα) agonists. Recent laboratory and clinical observations indicate that they are also anti-atherosclerotic. Mechanisms responsible, however, remain to be fully understood. The present study was designed to elucidate modulation of PAI-1 expression in adipose cells by fibrates as a potential mechanism. Expression of PPARα was verified by PCR, immunohistochemistry, and Western blotting. In cultured preadipocytes and adipocytes gemfibrozil and fenofibrate significantly reduced PAI-1 protein expression by up to 55 ± 5% and 34 ± 4% under basal conditions and up to 56 ± 6% and 31 ± 6% under conditions of stimulation of the cells with 40 pM trans-Keywords forming growth factor (TGF)β, respectively. Quantification of mRNA showed that the gemfibrozil-induced effect was at least in part regulated at the transcriptional level. Incubations with non-fibrate PPARα agonists showed similar reductions in PAI-1 expression. The decrease in PAI-1 expression induced by gemfibrozil was inhibited by MK886, a PPARα inhibitor. Furthermore, preadipocytes isolated from PPARα-deficient mice produced significantly more PAI-1 than those from wild-type mice upon stimulation with TGFβ. Finally, fenofibrate reduced PAI-1 expression both in plasma and adipose tissue of hyperlipidemic mice. Our data support the view that PPARα activation down-regulates PAI-expression in adipose cells that may contribute in part to the reduction in cardiovascular mortality seen with fibrates in clinical trials.

Rationale: Fatty acid oxidation is transcriptionally regulated by peroxisome proliferator–activated receptor (PPAR)α and under normal conditions accounts for 70% of cardiac ATP content. Reduced Ppara expression during sepsis and heart failure leads to reduced fatty acid oxidation and myocardial energy deficiency. Many of the transcriptional regulators of Ppara are unknown. Objective: To determine the role of Krüppel-like factor 5 (KLF5) in transcriptional regulation of Ppara . Methods and Results: We discovered that KLF5 activates Ppara gene expression via direct promoter binding. This is blocked in hearts of septic mice by c-Jun, which binds an overlapping site on the Ppara promoter and reduces transcription. We generated cardiac myocyte–specific Klf5 knockout mice that showed reduced expression of cardiac Ppara and its downstream fatty acid metabolism–related targets. These changes were associated with reduced cardiac fatty acid oxidation, ATP levels, increased triglyceride accumulation, and cardiac dysfunction. Diabetic mice showed parallel changes in cardiac Klf5 and Ppara expression levels. Conclusions: Cardiac myocyte KLF5 is a transcriptional regulator of Ppara and cardiac energetics.

Circulating fatty acids must cross the endothelial cell (EC) barrier to supply cardiomyocytes (CM). How this occurs is unknown. Cluster of differentiation (CD) 36 is a membrane associated protein whose total body deletion leads to reduced uptake of non-esterified fatty acids by heart, skeletal muscle and adipose tissue. To determine the contribution of EC versus CM CD36 in heart lipid uptake, we floxed CD36 and created EC- and CM-specific knockout (KO) mice. CD36 mRNA was reduced >50% in the heart, lung and skeletal muscle of EC-CD36 KO mice; CM-CD36 KO mice also had an ~50% reduction of CD36 mRNA levels in the heart. Both CM- and EC-specific CD36 ablation altered heart mRNA levels of glucose transport and oxidation genes (e.g. Glut1 ~2-fold increased, PDK4 ~0.5-fold decreased); these changes were similar to those found in mice with total body CD36 deletion. Loss of EC-CD36 led to increased plasma free fatty acid levels and prevented heart lipid droplet accumulation after an overnight fast (assessed by EM and oil red O staining). Lipid droplet accumulation was less affected in CM-CD36 KO hearts. To quantify the role of CD36 in the uptake of short chain vs. long chain fatty acids we simultaneously injected mice with radiolabeled [14C]hexanoic acid and [3H]oleic acid. Compared to both floxed-CD36 and CM-CD36 KO mice, plasma clearance of oleic acid was significantly delayed, and heart and quadriceps muscle uptake of oleic acid was reduced >50% in EC-CD36 KO and total-CD36 KO mice. Hexanoic acid uptake was not decreased by either deletion. Therefore, CD36 in EC is needed for the accumulation of long chain fatty acids in the heart and appears to be required for movement of fatty acids across the EC barrier.

Krüppel-like factors (KLF) affect metabolism. Lipopolysaccharide-induced sepsis reduced cardiac PPARα and increased KLF5 (8-fold) more than any cardiac KLF isoform detected by whole genome microarray analysis. In silico analysis of ppara gene promoter predicted two KLF5 binding sites that overlap with c-Jun (AP-1) binding sites: -792/-772 bp and -719/-698 bp. Infection of a mouse cardiomyocyte cell line (HL-1) with adenovirus expressing constitutively active c-Jun reduced, while Ad-KLF5 increased PPARα mRNA in a dose-dependent manner. Chromatin immunoprecipitation (ChIP) showed that c-Jun binds both -792/-772 bp and -719/-698 on ppara promoter while KLF5 binds on -792/-772 bp. ChIP on LPS-treated HL-1 cells showed that c-Jun binding on -792/-772 bp prohibits KLF5 binding. We generated a cardiomyocyte-specific KLF5 knockout mouse (αMHC-KLF5-/-), which had 50% normal cardiac function. Cardiomyocyte-specific KLF5 ablation reduced PPARα (50%) and several fatty acid metabolism-associated genes such as CD36 (40%), LpL (20%), PGC1α (45%), AOX (28%) and Cpt1 (45%). As PPARα regulates cardiac fatty acid metabolism, we tested whether cardiac KLF5 is modulated in diabetes, when cardiac PPARα and lipid changes occur. I.p. injection of streptozotocin (STZ) in C57BL/6 mice increased plasma glucose (2.9-fold) and reduced cardiac KLF5 and PPARα gene expression; similar to STZ-treated rats but unlike what had been found in a different mouse strain (C57BL/6 x DBA2) treated with STZ. Treatment of HL-1 cells with increased glucose-containing medium (1 mg/ml) reduced KLF5 (80%) and PPARα (65%), as well as fatty acid metabolism markers, such as AOX (85%), Cpt1β (70%), LCAD (80%) and VLCAD (85%). On the other hand GLUT1 and GLUT4 were increased (30% and 20%) and PDK4 was reduced (65%) indicating increased glucose utilization. A model of non-insulin dependent hyperglycemia (ob/ob mice) had reduced cardiac KLF5 (60%) and PPARα (65%). Correction of hyperglycemia in STZ-treated C57BL/6 mice by pharmacological (dapagliflozin) or antisense oligonucleotide inhibition of kidney’s sodium glucose transporter 2 (SGLT2), restored KLF5 and PPARα gene expression. Thus, KLF5 is a transcriptional regulator of cardiac PPARα that is driven by changes in plasma glucose levels

Objective— Diabetic hypertriglyceridemia is thought to be primarily driven by increased hepatic de novo lipogenesis. However, experiments in animal models indicated that insulin deficiency should decrease hepatic de novo lipogenesis and reduce plasma triglyceride levels. Approach and Results— To address the discrepancy between human data and genetically altered mouse models, we investigated whether insulin-deficient diabetic mice had triglyceride changes that resemble those in diabetic humans. Streptozotocin-induced insulin deficiency increased plasma triglyceride levels in mice. Contrary to the mouse models with impaired hepatic insulin receptor signaling, insulin deficiency did not reduce hepatic triglyceride secretion and de novo lipogenesis-related gene expression. Diabetic mice had a marked decrease in postprandial triglycerides clearance, which was associated with decreased lipoprotein lipase and peroxisome proliferator-activated receptor α mRNA levels in peripheral tissues and decreased lipoprotein lipase activity in skeletal muscle, heart, and brown adipose tissue. Diabetic heterozygous lipoprotein lipase knockout mice had markedly elevated fasting plasma triglyceride levels and prolonged postprandial triglycerides clearance. Conclusions— Insulin deficiency causes hypertriglyceridemia by decreasing peripheral lipolysis and not by an increase in hepatic triglycerides production and secretion.

Background— Costimulatory cascades such as the CD40L-CD40 dyad enhance immune cell activation and inflammation during atherosclerosis. Here, we tested the hypothesis that CD40 directly modulates traits of the metabolic syndrome in diet-induced obesity in mice. Methods and Results— To induce the metabolic syndrome, wild-type or CD40 −/− mice consumed a high-fat diet for 20 weeks. Unexpectedly, CD40 −/− mice exhibited increased weight gain, impaired insulin secretion, augmented accumulation of inflammatory cells in adipose tissue, and enhanced proinflammatory gene expression. This proinflammatory and adverse metabolic phenotype could be transplanted into wild-type mice by reconstitution with CD40-deficient lymphocytes, indicating a major role for CD40 in T or B cells in this context. Conversely, therapeutic activation of CD40 signaling by the stimulating antibody FGK45 abolished further weight gain during the study, lowered glucose levels, improved insulin sensitivity, and suppressed adipose tissue inflammation. Mechanistically, CD40 activation decreased the expression of proinflammatory cytokines in T cells but not in B cells or macrophages. Finally, repopulation of lymphocyte-free Rag1 −/− mice with CD40 −/− T cells provoked dysmetabolism and inflammation, corroborating a protective role of CD40 on T cells in the metabolic syndrome. Finally, levels of soluble CD40 showed a positive association with obesity in humans, suggesting clinical relevance of our findings. Conclusions— We present the surprising finding that CD40 deficiency on T cells aggravates whereas activation of CD40 signaling improves adipose tissue inflammation and its metabolic complications. Therefore, positive modulation of the CD40 pathway might describe a novel therapeutic concept against cardiometabolic disease.

Rupture of the ventricular myocardium is an often lethal complication after myocardial infarction. Due to the dramatic hemodynamics and the short time frame between ventricular rupture and surgical closure of the defect, additional therapeutic strategies are needed. Here we report the successful therapy of ventricular rupture by percutaneous intrapericardial instillation of fibrin glue in a 72-year-old male patient with postinfarct angina secondary to anterior myocardial infarction.

We tested whether a high fat diet (HFD) containing the inflammatory dietary fatty acid palmitate or insulin deficient diabetes altered the remodeling of atherosclerotic plaques in LDL receptor knockout (Ldlr-/-) mice. Cholesterol reduction was achieved by using a helper-dependent adenovirus (HDAd) carrying the gene for the low-density lipoprotein receptor (Ldlr; HDAd-LDLR). After injection of the HDAd-LDLR, mice consuming either HFD, which led to insulin resistance but not hyperglycemia, or low fat diet (LFD), showed regression compared to baseline. However there was no difference between the two groups in terms of atherosclerotic lesion size, or CD68+ cell and lipid content. Because of the lack of effects of these two diets, we then tested whether viral-mediated cholesterol reduction would lead to defective regression in mice with greater hyperglycemia. In both normoglycemic and streptozotocin (STZ)-treated hyperglycemic mice, HDAd-LDLR significantly reduced plasma cholesterol levels, decreased atherosclerotic lesion size, reduced macrophage area and lipid content, and increased collagen content of plaque in the aortic sinus. However, reductions in anti-inflammatory and ER stress-related genes were less pronounced in STZ-diabetic mice compared to non-diabetic mice. In conclusion, HDAd-mediated Ldlr gene therapy is an effective and simple method to induce atherosclerosis regression in Ldlr-/- mice in different metabolic states.

Objective: The accumulation of inflammatory leukocytes is a prerequisite of adipose tissue inflammation during cardiometabolic disease. We previously reported that a genetic deficiency of the intracellular signaling adaptor TRAF5 (TNF [tumor necrosis factor] receptor–associated factor 5) accelerates atherosclerosis in mice by increasing inflammatory cell recruitment. Here, we tested the hypothesis that an impairment of TRAF5 signaling modulates adipose tissue inflammation and its metabolic complications in a model of diet-induced obesity in mice. Approach and Results: To induce diet-induced obesity and adipose tissue inflammation, wild-type or Traf5 −/− mice consumed a high-fat diet for 18 weeks. Traf5 −/− mice showed an increased weight gain, impaired insulin tolerance, and increased fasting blood glucose. Weight of livers and peripheral fat pads was increased in Traf5 −/− mice, whereas lean tissue weight and growth were not affected. Flow cytometry of the stromal vascular fraction of visceral adipose tissue from Traf5 −/− mice revealed an increase in cytotoxic T cells, CD11c + macrophages, and increased gene expression of proinflammatory cytokines and chemokines. At the level of cell types, expression of TNFα, MIP (macrophage inflammatory protein)-1α, MCP (monocyte chemoattractant protein)-1, and RANTES (regulated on activation, normal T-cell expressed and secreted) was significantly upregulated in Traf5 -deficient adipocytes but not in Traf5 -deficient leukocytes from visceral adipose tissue. Finally, Traf5 expression was lower in adipocytes from obese patients and mice and recovered in adipose tissue of obese patients one year after bariatric surgery. Conclusions: We show that a genetic deficiency of TRAF5 in mice aggravates diet-induced obesity and its metabolic derangements by a proinflammatory response in adipocytes. Our data indicate that TRAF5 may promote anti-inflammatory and obesity-preventing signaling events in adipose tissue.