Liver-targeted Angptl4 silencing by antisense oligonucleotide treatment attenuates hyperlipidemia and atherosclerosis development in APOE*3-Leiden.CETP mice.

BACKGROUND AND AIMS: Angiopoietin-like 3 (ANGPTL3) and 4 (ANGPTL4) inhibit lipoprotein lipase to regulate tissue fatty acid uptake from triglyceride-rich lipoproteins such as VLDL. While pharmacological inhibition of ANGPTL3 is being evaluated as lipid-lowering strategy, systemic ANGPTL4 inhibition is not pursued due to adverse effects. This study aimed to compare the therapeutic potential of liver-specific Angptl3 and Angptl4 silencing to attenuate hyperlipidemia and atherosclerosis development in APOE*3-Leiden.CETP mice, a well-established humanized model for lipoprotein metabolism. METHODS AND RESULTS: Mice were subcutaneously injected twice-weekly with saline or liver-targeted antisense oligonucleotides against Angptl3, Angptl4, both, or a scrambled oligonucleotide. Plasma lipid levels, VLDL clearance and hepatic VLDL production were determined, and atherosclerosis development was assessed. For toxicological evaluation, cynomolgus monkeys were treated with three dosages of liver-targeted ANGPTL4-silencing oligonucleotides.Liver-targeted Angptl4 silencing reduced plasma triglycerides (-48%) and total cholesterol (-56%), explained by higher VLDL-derived fatty acid uptake by brown adipose tissue and lower VLDL production by the liver. Accordingly, Angptl4 silencing reduced atherosclerotic lesion size (-86%) and improved lesion stability. Hepatic Angptl3 silencing similarly attenuated hyperlipidemia and atherosclerosis development. While Angptl3 and Angptl4 silencing lowered plasma triglycerides in the refed and fasted state, respectively, combined Angptl3/4 silencing lowered plasma triglycerides independent of nutritional state. In cynomolgus monkeys, anti-ANGPTL4 ASO treatment was well tolerated without adverse effects. CONCLUSIONS: Liver-targeted Angptl4 silencing potently attenuates hyperlipidemia and atherosclerosis development in APOE*3-Leiden.CETP mice, and liver-targeted ANGPTL4 silencing is well-tolerated in non-human primates. These data warrant further clinical development of liver-targeted ANGPTL4 silencing.

The impact of statin use on sepsis mortality.

BACKGROUND: Statins exert pleiotropic anti-inflammatory and antioxidant effects in addition to their cholesterol-lowering properties. This study aimed to investigate whether statin use is associated with improved outcomes of sepsis. METHODS: Data from sepsis patients were extracted from the Medical Information Mart for Intensive Care IV database. Patients with a history of receiving prescriptions for statins (i.e. atorvastatin, lovastatin, pitavastatin, pravastatin, rosuvastatin, or simvastatin) were matched with non-users using propensity-score matching, to balance confounding factors between the groups. Mendelian Randomization (MR) analyses were performed using information from the UK Biobank dataset to explore the potential causal link between low-density lipoprotein cholesterol (LDL-C) levels and LDL-C lowering effects via genetically inhibiting ß­hydroxy ß-methylglutaryl-coenzyme A reductase and the susceptibility to sepsis, and the sepsis-related 28-day mortality. MAIN RESULTS: 90-day mortality rate was lower among the 10,323 statin users when compared to matched non-users [hazard ratio (HR): 0.612, 95 % CI: 0.571 to 0.655]. In-hospital mortality was also lower for statin users compared to non-users (11.3% vs. 17.8 %, p < 0.0001, HR: 0.590, 95 % CI: 0.548 to 0.634). Statin use was associated with better outcome in all investigated subpopulations apart from patients with severe liver disease. MR analyses further pointed toward pleiotropic effects beyond lipid-lowering effects of statins on sepsis-related outcomes. CONCLUSIONS: Statin use is associated with improved outcomes following sepsis-related ICU admission, most likely from its pleiotropic properties, characterized by lower 90-day and in-hospital mortality among statin users.

Brown adipose tissue facilitates the fever response following infection with Salmonella enterica serovar Typhimurium in mice.

Brown adipose tissue (BAT) combusts lipids and glucose to generate heat. Via this process of nonshivering thermogenesis, BAT plays a pivotal role in thermoregulation in cold environments, but its contribution to immune-induced fever is less clear. Male APOE∗3-Leiden.CETP mice, a well-established model for human-like lipoprotein metabolism, and wild-type mice were given an intraperitoneal injection of Salmonella enterica serovar Typhimurium (S.tm). Energy expenditure and substrate utilization, plasma lipid levels, fatty acid (FA) uptake by adipose tissues, and lipid content and thermogenic markers in adipose tissues were examined. S.tm infection led to a set of characteristic symptoms, including elevated body temperature and decreased body weight. Whole-body energy expenditure was significantly decreased 72 h postinfection, but fat oxidation was increased and accompanied by a substantial reduction in plasma triglyceride (TG) levels as demonstrated in APOE∗3-Leiden.CETP mice. S.tm infection strongly increased uptake of FAs from TG-rich lipoproteins by BAT, which showed a positive correlation with body temperature in infected mice. Upon histological examination of BAT from wild-type or APOE∗3-Leiden.CETP mice, elevated levels of tyrosine hydroxylase were observed, indicative of stimulated sympathetic activity. In addition, the gene expression profile was consistent with more adrenergic stimulation, while lipid content was reduced. Furthermore, browning of white adipose tissue was observed, evidenced by a modest increase in TG-derived FA uptake, the presence of multilocular cells, and induction of uncoupling protein 1 expression. We proposed that BAT, or thermogenic adipose tissue in general, is involved in the maintenance of elevated body temperature upon invasive bacterial infection.

Doublecortin-like knockdown in mice attenuates obesity by stimulating energy expenditure in adipose tissue.

Crosstalk between peripheral metabolic organs and the central nervous system is essential for body weight control. At the base of the hypothalamus, ß-tanycytes surround the portal capillaries and function as gatekeepers to facilitate transfer of substances from the circulation into the cerebrospinal fluid and vice versa. Here, we investigated the role of the neuroplasticity gene doublecortin-like (DCL), highly expressed by ß-tanycytes, in body weight control and whole-body energy metabolism. We demonstrated that DCL-knockdown through a doxycycline-inducible shRNA expression system prevents body weight gain by reducing adiposity in mice. DCL-knockdown slightly increased whole-body energy expenditure possibly as a result of elevated circulating thyroid hormones. In white adipose tissue (WAT) triglyceride uptake was increased while the average adipocyte cell size was reduced. At histological level we observed clear signs of browning, and thus increased thermogenesis in WAT. We found no indications for stimulated thermogenesis in brown adipose tissue (BAT). Altogether, we demonstrate an important, though subtle, role of tanycytic DCL in body weight control through regulation of energy expenditure, and specifically WAT browning. Elucidating mechanisms underlying the role of DCL in regulating brain-peripheral crosstalk further might identify new treatment targets for obesity.

Tirzepatide modulates the regulation of adipocyte nutrient metabolism through long-acting activation of the GIP receptor.

Tirzepatide, a glucose-dependent insulinotropic polypeptide/glucagon-like peptide 1 receptor (GIPR/GLP-1R) agonist, has, in clinical trials, demonstrated greater reductions in glucose, body weight, and triglyceride levels compared with selective GLP-1R agonists in people with type 2 diabetes (T2D). However, cellular mechanisms by which GIPR agonism may contribute to these improved efficacy outcomes have not been fully defined. Using human adipocyte and mouse models, we investigated how long-acting GIPR agonists regulate fasted and fed adipocyte functions. In functional assays, GIPR agonism enhanced insulin signaling, augmented glucose uptake, and increased the conversion of glucose to glycerol in a cooperative manner with insulin; however, in the absence of insulin, GIPR agonists increased lipolysis. In diet-induced obese mice treated with a long-acting GIPR agonist, circulating triglyceride levels were reduced during oral lipid challenge, and lipoprotein-derived fatty acid uptake into adipose tissue was increased. Our findings support a model for long-acting GIPR agonists to modulate both fasted and fed adipose tissue function differentially by cooperating with insulin to augment glucose and lipid clearance in the fed state while enhancing lipid release when insulin levels are reduced in the fasted state.

Cold exposure increases circulating fibroblast growth factor 21 in the evening in males and females.

Objectives: Cold exposure is linked to cardiometabolic benefits. Cold activates brown adipose tissue (BAT), increases energy expenditure, and induces secretion of the hormones fibroblast growth factor 21 (FGF21) and growth differentiation factor 15 (GDF15). The cold-induced increase in energy expenditure exhibits a diurnal rhythm in men. Therefore, we aimed to investigate the effect of cold exposure on serum FGF21 and GDF15 levels in humans and whether cold-induced changes in FGF21 and GDF15 levels differ between morning and evening in males and females. Method: In this randomized cross-over study, serum FGF21 and GDF15 levels were measured in healthy lean males (n = 12) and females (n = 12) before, during, and after 90 min of stable cold exposure in the morning (07:45 h) and evening (19:45 h) with a 1-day washout period in between. Results: Cold exposure increased FGF21 levels in the evening compared to the morning both in males (+61% vs -13%; P < 0.001) and in females (+58% vs +8%; P < 0.001). In contrast, cold exposure did not significantly modify serum GDF15 levels, and no diurnal variation was found. Changes in FGF21 and GDF15 levels did not correlate with changes in cold-induced energy expenditure in the morning and evening. Conclusion: Cold exposure increased serum FGF21 levels in the evening, but not in the morning, in both males and females. GDF15 levels were not affected by cold exposure. Thus, this study suggests that the timing of cold exposure may influence cold-induced changes in FGF21 levels but not GDF15 levels and seems to be independent of changes in energy expenditure.

DHCR24 inhibitor SH42 increases desmosterol without preventing atherosclerosis development in mice.

The liver X receptor (LXR) is considered a therapeutic target for atherosclerosis treatment, but synthetic LXR agonists generally also cause hepatic steatosis and hypertriglyceridemia. Desmosterol, a final intermediate in cholesterol biosynthesis, has been identified as a selective LXR ligand that suppresses inflammation without inducing lipogenesis. Δ24-Dehydrocholesterol reductase (DHCR24) converts desmosterol into cholesterol, and we previously showed that the DHCR24 inhibitor SH42 increases desmosterol to activate LXR and attenuate experimental peritonitis and metabolic dysfunction-associated steatotic liver disease. Here, we aimed to evaluate the effect of SH42 on atherosclerosis development in APOE∗3-Leiden.CETP mice and low-density lipoproteins (LDL) receptor knockout mice, models for lipid- and inflammation-driven atherosclerosis, respectively. In both models, SH42 increased desmosterol without affecting plasma lipids. While reducing liver lipids in APOE∗3-Leiden.CETP mice, and regulating populations of circulating monocytes in LDL receptor knockout mice, SH42 did not attenuate atherosclerosis in either model.

T cells with increased responsiveness cause obesity in mice without diet intervention.

Obesity is a complex multicausal disease that can cause morbidity and mortality, and there is need for improved knowledge on the underlying mechanisms. Using a mouse model of increased T cell responsiveness, we show that development of obesity can be driven by immune cells. This was confirmed with bone marrow transplantation and adoptive T cell transfer to several recipient mouse models. Single-cell RNA sequencing and CyTOF analysis showed that the mice display altered composition of circulating T cells and increased T cell activation in visceral adipose tissue, suggesting activated T cells as critical players in the increased fat mass. In this study, we provide evidence that obesity can be driven by immune cell activity and in particular by T cells, which could have broad implications for prevention and treatment of this condition.

Atherosclerosis: an overview of mouse models and a detailed methodology to quantify lesions in the aortic root.

Cardiovascular disease, the primary cause of human mortality globally, is predominantly caused by a progressive disorder known as atherosclerosis. Atherosclerosis refers to the process of accumulation of cholesterol-enriched lipoproteins and the concomitant initiation of inflammatory processes in the arterial wall, including the recruitment of immune cells. This leads to the formation of atherosclerotic plaques, initially causing a thickening of the arterial wall and narrowing of arteries. However, as plaque formation progresses, atherosclerotic plaques may become unstable and rupture, leading to a blood clot that blocks the affected artery or travels through the blood to block blood flow elsewhere. In the early 1990s, emerging gene editing methods enabled the development of apolipoprotein E knockout (Apoe-/- ) and low-density lipoprotein receptor knockout (Ldlr-/- ) mice. These mice have been instrumental in unraveling the complex pathogenesis of atherosclerosis. Around the same time, human APOE*3-Leiden transgenic mice were generated, which were more recently cross-bred with human cholesteryl ester transfer protein (CETP) transgenic mice to generate APOE*3-Leiden.CETP mice. This model appears to closely mimic human lipoprotein metabolism and responds to classic lipid-lowering interventions due to an intact ApoE-LDLR pathway of lipoprotein remnant clearance. In this review, we describe the role of lipid metabolism and inflammation in atherosclerosis development and highlight the characteristics of the frequently used animal models to study atherosclerosis, with a focus on mouse models, discussing their advantages and limitations. Moreover, we present a detailed methodology to quantify atherosclerotic lesion area within the aortic root region of the murine heart, as well as details required for scoring atherosclerotic lesion severity based on guidelines of the American Heart Association adapted for mice.

Fasting mimicking diet in diabetic mice partially preserves glomerular endothelial glycocalyx coverage, without changing the diabetic metabolic environment.

Intermittent fasting has become of interest for its possible metabolic benefits and reduction of inflammation and oxidative damage, all of which play a role in the pathophysiology of diabetic nephropathy. We tested in a streptozotocin (60 mg/kg)-induced diabetic apolipoprotein E knockout mouse model whether repeated fasting mimicking diet (FMD) prevents glomerular damage. Diabetic mice received 5 FMD cycles in 10 wk, and during cycles 1 and 5 caloric measurements were performed. After 10 wk, glomerular endothelial morphology was determined together with albuminuria, urinary heparanase-1 activity, and spatial mass spectrometry imaging to identify specific glomerular metabolic dysregulation. During FMD cycles, blood glucose levels dropped while a temporal metabolic switch was observed to increase fatty acid oxidation. Overall body weight at the end of the study was reduced together with albuminuria, although urine production was dramatically increased without affecting urinary heparanase-1 activity. Weight loss was found to be due to lean mass and water, not fat mass. Although capillary loop morphology and endothelial glycocalyx heparan sulfate contents were preserved, hyaluronan surface expression was reduced together with the presence of UDP-glucuronic acid. Mass spectrometry imaging further revealed reduced protein catabolic breakdown products and increased oxidative stress, not different from diabetic mice. In conclusion, although FMD preserves partially glomerular endothelial glycocalyx, loss of lean mass and increased glomerular oxidative stress argue whether such diet regimes are safe in patients with diabetes.NEW & NOTEWORTHY Repeated fasting mimicking diet (FMD) partially prevents glomerular damage in a diabetic mouse model; however, although endothelial glycocalyx heparan sulfate contents were preserved, hyaluronan surface expression was reduced in the presence of UDP-glucuronic acid. The weight loss observed was of lean mass, not fat mass, and increased glomerular oxidative stress argue whether such a diet is safe in patients with diabetes.

Hydrocortisone-associated death and hospital length of stay in patients with sepsis: A retrospective cohort of large-scale clinical care data.

PURPOSE: Sepsis is one of the leading causes of morbidity and mortality worldwide with approximately 50 million annual cases. There is ongoing debate on the clinical benefit of hydrocortisone in the prevention of death in septic patients. Here we evaluated the association between hydrocortisone treatment and mortality in patients diagnosed with sepsis in a large-scale clinical dataset. METHODS: Data from patients between 2008 and 2019 were extracted from the retrospective Medical Information Mart for Intensive Care IV (MIMIC-IV) database. Patients who received hydrocortisone after diagnosis were matched using propensity-score matching with patients who did not, to balance confounding (by indication and contraindication) factors between the groups. 90-day mortality and survivors' length of hospital stay was compared between patients who did or did not receive hydrocortisone. RESULTS: A total of 31,749 septic patients were included in the study (mean age: 67, men: 57.3%, in-hospital mortality: 15.6%). 90-day mortality was higher among the 1802 patients receiving hydrocortisone when compared with the 6348 matched non-users (hazard ratio: 1.35, 95% CI: 1.24-1.47). Hydrocortisone treatment was also associated with increased in-hospital mortality (40.9% vs. 27.6%, p < 0.0001) and prolonged hospital stay in those who survived until discharge (median 12.6 days vs. 10.8 days, p < 0.0001). Stratification for age, gender, ethnicity, occurrence of septic shock, and the need for vasopressor drug administration such as (nor)epinephrine did not reveal sub-population(s) benefiting of hydrocortisone use. CONCLUSION: Hydrocortisone treatment is associated with increased risk of death as well as prolonged hospital stay in septic patients. Although residual confounding (by indication) cannot be ruled out completely due to the observational nature of the study, the present study suggests clinical implication of hydrocortisone use in patients with sepsis.

Short-term Pre-operative Methionine Restriction Induces Browning of Perivascular Adipose Tissue and Improves Vein Graft Remodeling in Mice.

Short-term preoperative methionine restriction (MetR) shows promise as a translatable strategy to modulate the body's response to surgical injury. Its application, however, to improve post-interventional vascular remodeling remains underexplored. Here, we find that MetR protects from arterial intimal hyperplasia in a focal stenosis model and adverse vascular remodeling after vein graft surgery. RNA sequencing reveals that MetR enhances the brown adipose tissue phenotype in arterial perivascular adipose tissue (PVAT) and induces it in venous PVAT. Specifically, PPAR-α was highly upregulated in PVAT-adipocytes. Furthermore, MetR dampens the post-operative pro-inflammatory response to surgery in PVAT-macrophages in vivo and in vitro . This study shows for the first time that the detrimental effects of dysfunctional PVAT on vascular remodeling can be reversed by MetR, and identifies pathways involved in browning of PVAT. Furthermore, we demonstrate the potential of short-term pre-operative MetR as a simple intervention to ameliorate vascular remodeling after vascular surgery.

The importance of the circadian trough in glucocorticoid signaling: a variation on B-flat.

Glucocorticoid hormones are essential for health, but overexposure may lead to many detrimental effects, including metabolic, psychiatric, and bone disease. These effects may not only be due to increased overall exposure to glucocorticoids, but also to elevated hormone levels at the time of the physiological circadian trough of glucocorticoid levels. The late Mary Dallman developed a model that allows the differentiation between the effects of overall 24-hour glucocorticoid overexposure and the effects of a lack of circadian rhythmicity. For this, she continuously treated rats with a low dose of corticosterone (or "B"), which leads to a constant hormone level, without 24-hour overexposure using subcutaneously implanted pellets. The data from this "B-flat" model suggest that even modest elevations of glucocorticoid signaling during the time of the normal circadian trough of hormone secretion are a substantial contributor to the negative effects of glucocorticoids on health.

Combined GIP receptor and GLP1 receptor agonism attenuates NAFLD in male APOE∗3-Leiden.CETP mice.

BACKGROUND: Combined glucose-dependent insulinotropic polypeptide receptor (GIPR) and glucagon-like peptide-1 receptor (GLP1R) agonism is superior to single GLP1R agonism with respect to glycemic control and weight loss in obese patients with or without type 2 diabetes. As insulin resistance and obesity are strong risk factors for nonalcoholic fatty liver disease (NAFLD), in the current study we investigated the effects of combined GIPR/GLP1R agonism on NAFLD development. METHODS: Male APOE∗3-Leiden.CETP mice, a humanized model for diabetic dyslipidemia and NAFLD when fed a high-fat high-cholesterol diet, received subcutaneous injections with either vehicle, a GIPR agonist, a GLP1R agonist, or both agonists combined every other day. FINDINGS: GIPR and GLP1R agonism reduced body weight and additively lowered fasting plasma levels of glucose, triglycerides and total cholesterol. Strikingly, we report an additive reduction in hepatic steatosis as evidenced by lower hepatic lipid content and NAFLD scores. Underlying the lipid-lowering effects were a reduced food intake and intestinal lipid absorption and an increased uptake of glucose and triglyceride-derived fatty acids by energy-combusting brown adipose tissue. Combined GIPR/GLP1R agonism also attenuated hepatic inflammation as evidenced by a decreased number of monocyte-derived Kupffer cells and a reduced expression of inflammatory markers. Together, the reduced hepatic steatosis and inflammation coincided with lowered markers of liver injury. INTERPRETATION: We interpretate that GIPR and GLP1R agonism additively attenuate hepatic steatosis, lower hepatic inflammation, ameliorate liver injury, together preventing NAFLD development in humanized APOE∗3-Leiden.CETP mice. We anticipate that combined GIPR/GLP1R agonism is a promising strategy to attenuate NAFLD progression in humans. FUNDING: This work was supported by a grant from the Netherlands CardioVascular Research Initiative: the Dutch Heart Foundation, Dutch Federation of University Medical Centers, the Netherlands Organization for Health Research and Development, and the Royal Netherlands Academy of Sciences [CVON-GENIUS-II] to P.C.N.R., a Lilly Research Award Program [LRAP] Award to P.C.N.R. and S.K., a Dutch Heart Foundation [2017T016] grant to S.K., and an NWO-VENI grant [09150161910073] to M.R.B.; J.F.D.B. is supported by the Nutrition and Health initiative of the University of Groningen; Z.Y. is supported by a full-time PhD scholarship from the China Scholarship Council (201806850094 to Z.Y.).

Time-restricted feeding attenuates hypercholesterolaemia and atherosclerosis development during circadian disturbance in APOE∗3-Leiden.CETP mice.

BACKGROUND: Circadian disturbance (CD) is the consequence of a mismatch between endogenous circadian rhythms, behaviour, and/or environmental cycles, and frequently occurs during shift work. Shift work has been associated with elevated risk for atherosclerotic cardiovascular disease (asCVD) in humans, but evidence for the effectiveness of prevention strategies is lacking. METHODS: Here, we applied time-restricted feeding (TRF) as a strategy to counteract atherosclerosis development during CD in female APOE∗3-Leiden.CETP mice, a well-established model for humanized lipoprotein metabolism. Control groups were subjected to a fixed 12:12 h light-dark cycle, while CD groups were subjected to 6-h phase advancement every 3 days. Groups had either ad libitum (AL) access to food or were subjected to TRF with restricted food access to the dark phase. FINDINGS: TRF did not prevent the increase in the relative abundance of circulating inflammatory monocytes and elevation of (postprandial) plasma triglycerides during CD. Nonetheless, TRF reduced atherosclerotic lesion size and prevented an elevation in macrophage content of atherosclerotic lesions during CD, while it increased the relative abundance of anti-inflammatory monocytes, prevented activation of T cells, and lowered plasma total cholesterol levels and markers of hepatic cholesterol synthesis. These effects were independent of total food intake. INTERPRETATION: We propose that time restricted eating could be a promising strategy for the primary prevention of asCVD risk in shift workers, which warrants future study in humans. FUNDING: This work was funded by the Novo Nordisk Foundation, the Netherlands Ministry of Social Affairs and Employment, Amsterdam Cardiovascular Sciences, and the Dutch Heart Foundation.

Circadian control of white and brown adipose tissues.

White and brown adipose tissues are highly dynamic organs anticipating and responding to changes in the environment. The circadian timing system facilitates anticipation, and it is therefore not surprising that circadian disturbances, a prominent feature of modern 24/7 society, increase the risk for (cardio)metabolic diseases. In this mini-review, we will address mechanisms and strategies to mitigate disease risk associated with circadian disturbances. In addition, we discuss the opportunities arising from the knowledge we gained about circadian rhythms in these adipose tissues, including the application of chronotherapy, optimizing endogenous circadian rhythms to allow for more effective intervention, and the identification of novel therapeutic targets.

Phosphatidylinositol metabolism of the renal proximal tubule S3 segment is disturbed in response to diabetes.

Diabetes is a main risk factor for kidney disease, causing diabetic nephropathy in close to half of all patients with diabetes. Metabolism has recently been identified to be decisive in cell fate decisions and repair. Here we used mass spectrometry imaging (MSI) to identify tissue specific metabolic dysregulation, in order to better understand early diabetes-induced metabolic changes of renal cell types. In our experimental diabetes mouse model, early glomerular glycocalyx barrier loss and systemic metabolic changes were observed. In addition, MSI targeted at small molecule metabolites and glycero(phospho)lipids exposed distinct changes upon diabetes in downstream nephron segments. Interestingly, the outer stripe of the outer medullar proximal tubular segment (PT_S3) demonstrated the most distinct response compared to other segments. Furthermore, phosphatidylinositol lipid metabolism was altered specifically in PT_S3, with one of the phosphatidylinositol fatty acid tails being exchanged from longer unsaturated fatty acids to shorter, more saturated fatty acids. In acute kidney injury, the PT_S3 segment and its metabolism are already recognized as important factors in kidney repair processes. The current study exposes early diabetes-induced changes in membrane lipid composition in this PT_S3 segment as a hitherto unrecognized culprit in the early renal response to diabetes.

Combined glucose-dependent insulinotropic polypeptide receptor and glucagon-like peptide-1 receptor agonism attenuates atherosclerosis severity in APOE*3-Leiden.CETP mice.

BACKGROUND AND AIMS: Combined agonism of the glucose-dependent insulinotropic polypeptide receptor (GIPR) and the glucagon-like peptide-1 receptor (GLP1R) is superior to single GLP1R agonism in terms of glycemic control and lowering body weight in individuals with obesity and with or without type 2 diabetes mellitus. As both GIPR and GLP1R signaling have also been implicated in improving inflammatory responses and lipid handling, two crucial players in atherosclerosis development, here we aimed to investigate the effects of combined GIPR/GLP1R agonism in APOE*3-Leiden.CETP mice, a well-established mouse model for human-like lipoprotein metabolism and atherosclerosis development. METHODS: Female APOE*3-Leiden.CETP mice were fed a Western-type diet (containing 16% fat and 0.15% cholesterol) to induce dyslipidemia, and received subcutaneous injections with either vehicle, a GIPR agonist (GIPFA-085), a GLP1R agonist (GLP-140) or both agonists. In the aortic root area, atherosclerosis development was assessed. RESULTS: Combined GIPR/GLP1R agonism attenuated the development of severe atherosclerotic lesions, while single treatments only showed non-significant improvements. Mechanistically, combined GIPR/GLP1R agonism decreased markers of systemic low-grade inflammation. In addition, combined GIPR/GLP1R agonism markedly lowered plasma triglyceride (TG) levels as explained by reduced hepatic very-low-density lipoprotein (VLDL)-TG production as well as increased TG-derived fatty acid uptake by brown and white adipose tissue which was coupled to enhanced hepatic uptake of core VLDL remnants. CONCLUSIONS: Combined GIPR/GLP1R agonism attenuates atherosclerosis severity by diminishing inflammation and increasing VLDL turnover. We anticipate that combined GIPR/GLP1R agonism is a promising strategy to lower cardiometabolic risk in humans.

Lipoproteins act as vehicles for lipid antigen delivery and activation of invariant natural killer T cells.

Invariant natural killer T (iNKT) cells act at the interface between lipid metabolism and immunity because of their restriction to lipid antigens presented on CD1d by antigen-presenting cells (APCs). How foreign lipid antigens are delivered to APCs remains elusive. Since lipoproteins routinely bind glycosylceramides structurally similar to lipid antigens, we hypothesized that circulating lipoproteins form complexes with foreign lipid antigens. In this study, we used 2-color fluorescence correlation spectroscopy to show, for the first time to our knowledge, stable complex formation of lipid antigens α-galactosylceramide (αGalCer), isoglobotrihexosylceramide, and OCH, a sphingosine-truncated analog of αGalCer, with VLDL and/or LDL in vitro and in vivo. We demonstrate LDL receptor-mediated (LDLR-mediated) uptake of lipoprotein-αGalCer complexes by APCs, leading to potent complex-mediated activation of iNKT cells in vitro and in vivo. Finally, LDLR-mutant PBMCs of patients with familial hypercholesterolemia showed impaired activation and proliferation of iNKT cells upon stimulation, underscoring the relevance of lipoproteins as a lipid antigen delivery system in humans. Taken together, circulating lipoproteins form complexes with lipid antigens to facilitate their transport and uptake by APCs, leading to enhanced iNKT cell activation. This study thereby reveals a potentially novel mechanism of lipid antigen delivery to APCs and provides further insight into the immunological capacities of circulating lipoproteins.