Monique T. Mulder

Human CD4 ⁺ T cells utilize nutrients, including lipids, to support their activation and polarization. Considering the pivotal role of lipoproteins in lipid transport, we reasoned that lipoprotein uptake and processing could effect CD4 ⁺ T cell function. Here, we demonstrate that activation of human CD4 ⁺ T cells induced expression of LDL receptor (LDLR) to facilitate LDLR-mediated endocytosis of LDL. Degradation of surface LDLR on CD4 ⁺ T cells with PCSK9 hampered activation and proliferation of the cells. Lipoprotein deprivation or blocking of lysosomal cholesterol egress impaired activation of mechanistic target of rapamycin complex 1 (mTORC1), affecting CD4 ⁺ T cell activation and proliferation. Furthermore, lipoprotein deprivation of cultured primary CD4 ⁺ T cells lead to reduced expression of c-MAF and FOXP3, key transcription factors for IL-10, accompanied by reduced IL-10 secretion. The pivotal role of LDLR-mediated lipoprotein uptake for mTORC1 activity, c-MAF and FOXP3 expression, and IL-10 secretion was confirmed using LDLR-dysfunctional CD4 ⁺ T cells from patients with homozygous familial hypercholesterolemia. Our study offers valuable insights into the lipoprotein metabolism of human CD4 ⁺ T cells and their reliance on the LDLR pathway for activation and polarization, a feature that may be leveraged to modulate CD4 ⁺ T cell function.

South Asians (SAs) in the UK are at an increased risk of cardiovascular disease (CVD), develop type 2 diabetes mellitus at a lower age and body mass index, and have a lower high-density lipoprotein cholesterol (HDL-C) concentration than their white European (EU) counterparts. The failure of HDL-C raising therapies for CVD risk reduction has turned attention to its composition and function. A previous study comparing the effect of moderate weight gain on SA and EU men found baseline and weight gain-induced ethnic differences in body composition, adipocyte function and insulin resistance (ClinicalTrials.gov registration: NCT02399423). This study investigated differences in HDL protein composition, subclass distribution and in vitro vascular functions at baseline and after weight gain in the same cohort of men. HDL protein composition was determined by nano liquid chromatography tandem mass spectrometry using label-free quantification. HDL subclass distribution was measured by native gel electrophoresis. HDL in vitro paraoxonase-1 (PON-1) activity was measured by monitoring the PON-1 mediated hydrolysis of phenylacetate. In vitro HDL anti-inflammatory function was assessed in an endothelial cell assay of adhesion molecule inhibition. SAs had higher levels of immunity- and inflammation-related proteins and a detrimental profile of lipid metabolism-related proteins at baseline and with weight gain (including lower apolipoprotein (apo) A-IV and apoF and higher apoC-III) compared with EU. HDL subclass distribution and in vitro vascular function were not different between EUs and SAs. HDL protein composition reflects systemic physiology and acts as a mechanistic marker of impaired lipid metabolism in SAs.

Marine sterols from brown seaweeds, particularly fucosterol and its oxidized derivative saringosterol, have shown therapeutic potential for Alzheimer’s disease (AD) and cardiovascular diseases. Here, we aimed to elucidate the cellular and in vivo mechanisms underlying their beneficial effects. In human HepG2 hepatocytes and CCF-STTG1 astrocytoma cells, we assessed liver x receptor (LXRα /LXRβ) activation, sterol uptake, and effects on cholesterol metabolism using luciferase reporter assays, GC–MS sterol profiling, and ¹³ C-acetate incorporation. In THP-1–derived macrophages, we evaluated sterol-induced cholesterol efflux using radiolabeled [ ³ H]-cholesterol assays and characterized anti-inflammatory responses by quantifying lipopolysaccharide (LPS) -induced cytokine production. Wild-type C57BL/6J mice were fed diets enriched with either fucosterol (0.2% w/w) or saringosterol (0.02% w/w) for 7 days, after which sterol profiles in serum, liver, and brain were quantified by GC–MS. Hippocampal transcriptional responses were assessed by RNA sequencing. Both fucosterol and saringosterol were internalized by HepG2 and CCF-STTG1 cells and activated LXRα/β, but elicited distinct metabolic effects: fucosterol increased cholesterol synthesis and intracellular desmosterol, whereas saringosterol reduced both; only saringosterol suppressed LPS-induced interleukin (IL)-6 and tumor necrosis factor (TNF)-α production in macrophages, while both enhanced cholesterol efflux. In vivo , fucosterol somewhat elevated hepatic desmosterol and decreased 5α-cholestanol and circulating oxysterols, whereas saringosterol also increased hepatic desmosterol and elevated 7α-hydroxycholesterol in liver and brain as well as serum 27-hydroxycholesterol. Transcriptome analysis revealed that fucosterol primarily modulated synaptic signaling and hormonal pathways linked to neuronal plasticity, while saringosterol affected protein quality control and neurodegenerative pathways. These data are the first on the direct comparison of the cellular and in vivo effects of fucosterol and saringosterol, revealing shared LXR activation but divergent impacts on hepatic, brain and systemic cholesterol metabolism and expression of genes involved in neural pathways, indicating complementary neuroprotective effects with therapeutic potential for AD and related disorders.

APOE4 encoding apolipoprotein (Apo)E4 is the strongest genetic risk factor for Alzheimer's disease (AD). ApoE is key in intercellular lipid trafficking. Fatty acids are essential for brain integrity and cognitive performance and are implicated in neurodegeneration. We determined the sex‐ and age‐dependent effect of AD and APOE4 on brain free fatty acid (FFA) profiles. FFA profiles were determined by LC–MS/MS in hippocampus, cortex, and cerebellum of female and male, young (≤3 months) and older (>5 months), transgenic APOE3 and APOE4 mice with and without five familial AD (FAD) mutations (16 groups; n = 7–10 each). In the different brain regions, females had higher levels than males of either saturated or polyunsaturated FFAs or both. In the hippocampus of young males, but not of older males, APOE4 and FAD each induced 1.3‐fold higher levels of almost all FFAs. In young and older females, FAD and to a less extent APOE4‐induced shifts among saturated, monounsaturated, and polyunsaturated FFAs without affecting total FFA levels. In cortex and cerebellum, APOE4 and FAD had only minor effects on individual FFAs. The effects of APOE4 and FAD on FFA levels and FFA profiles in the three brain regions were strongly dependent of sex and age, particularly in the hippocampus. Here, most FFAs that are affected by FAD are similarly affected by APOE4. Since APOE4 and FAD affected hippocampal FFA profiles already at young age, these APOE4‐induced alterations may modulate the pathogenesis of AD. image

Background: Brown seaweed is promising for the treatment of type 2 diabetes mellitus (T2DM). Its bioactive constituents can positively affect plasma glucose homeostasis in healthy humans. We investigated the effect of the brown seaweeds Sargassum (S.) fusiforme and Fucus (F.) vesiculosus in their natural form on glucose regulation in patients with T2DM. Methods: We conducted a randomized, double-blind, placebo-controlled pilot trial. Thirty-six participants with T2DM received, on a daily basis, either 5 g of dried S. fusiforme, 5 g of dried F. vesiculosus, or 0.5 g of dried Porphyra (control) for 5 weeks, alongside regular treatment. The primary outcome was the between-group difference in the change in weekly average blood glucose levels (continuous glucose monitoring). The secondary outcomes were the changes in anthropometrics, plasma lipid levels, and dietary intake. The data were analyzed using a linear mixed-effects model. Results: The change in weekly average glucose levels was 8.2 ± 2.1 to 9.0 ± 0.7 mmol/L (p = 0.2) in the S. fusiforme group (n = 12) and 10.1 ± 3.3 to 9.2 ± 0.7 mmol/L (p = 0.9) in the F. vesiculosus group (n = 10). The between-group difference was non-significant. Similarly, no between-group differences were observed for the changes in the secondary outcomes. Discussion: A daily intake of 5 g of fresh, dried S. fusiforme or F. vesiculosus alongside regular treatment had no differential effect on weekly average blood glucose levels in T2DM.

Multiple common cardiovascular comorbidities produce coronary microvascular dysfunction. We previously observed in swine that a combination of diabetes mellitus (DM), high fat diet (HFD) and chronic kidney disease (CKD) induced systemic inflammation, increased oxidative stress and produced coronary endothelial dysfunction, altering control of coronary microvascular tone via loss of NO bioavailability, which was associated with an increase in circulating endothelin (ET). In the present study, we tested the hypotheses that (1) ROS scavenging and (2) ET_A+B-receptor blockade improve myocardial oxygen delivery in the same female swine model. Healthy female swine on normal pig chow served as controls (Normal). Five months after induction of DM (streptozotocin, 3 × 50 mg kg⁻¹ i.v.), hypercholesterolemia (HFD) and CKD (renal embolization), swine were chronically instrumented and studied at rest and during exercise. Sustained hyperglycemia, hypercholesterolemia and renal dysfunction were accompanied by systemic inflammation and oxidative stress. In vivo ROS scavenging (TEMPOL + MPG) reduced myocardial oxygen delivery in DM + HFD + CKD swine, suggestive of a vasodilator influence of endogenous ROS, while it had no effect in Normal swine. In vitro wire myography revealed a vasodilator role for hydrogen peroxide (H₂O₂) in isolated small coronary artery segments from DM + HFD + CKD, but not Normal swine. Increased catalase activity and ceramide production in left ventricular myocardial tissue of DM + HFD + CKD swine further suggest that increased H₂O₂ acts as vasodilator ROS in the coronary microvasculature. Despite elevated ET-1 plasma levels in DM + HFD + CKD swine, ET_A+B blockade did not affect myocardial oxygen delivery in Normal or DM + HFD + CKD swine. In conclusion, loss of NO bioavailability due to 5 months exposure to multiple comorbidities is partially compensated by increased H₂O₂-mediated coronary vasodilation.

We previously demonstrated that diet supplementation with seaweed Sargassum fusiforme (S. fusiforme) prevented AD-related pathology in a mouse model of Alzheimer’s Disease (AD). Here, we tested a lipid extract of seaweed Himanthalia elongata (H. elongata) and a supercritical fluid (SCF) extract of S. fusiforme that is free of excess inorganic arsenic. Diet supplementation with H. elongata extract prevented cognitive deterioration in APPswePS1ΔE9 mice. Similar trends were observed for the S. fusiforme SCF extract. The cerebral amyloid-β plaque load remained unaffected. However, IHC analysis revealed that both extracts lowered glial markers in the brains of APPswePS1ΔE9 mice. While cerebellar cholesterol concentrations remained unaffected, both extracts increased desmosterol, an endogenous LXR agonist with anti-inflammatory properties. Both extracts increased cholesterol efflux, and particularly, H. elongata extract decreased the production of pro-inflammatory cytokines in LPS-stimulated THP-1-derived macrophages. Additionally, our findings suggest a reduction of AD-associated phosphorylated tau and promotion of early oligodendrocyte differentiation by H. elongata. RNA sequencing on the hippocampus of one-week-treated APPswePS1ΔE9 mice revealed effects of H. elongata on, amongst others, acetylcholine and synaptogenesis signaling pathways. In conclusion, extracts of H. elongata and S. fusiforme show potential to reduce AD-related pathology in APPswePS1ΔE9 mice. Increasing desmosterol concentrations may contribute to these effects by dampening neuroinflammation.

Background: Previous studies showed fluctuating lipid levels during the menstrual cycle in healthy women with normal cholesterol (nChol). Cycle-related variations in lipid levels in women with familial hypercholesterolemia (FH) have not been studied, while these might have important consequences for lipid management. Purpose: To investigate menstrual cycle-related fluctuations in lipid levels in women with FH compared to those with nChol. Methods: In the Netherlands and Norway, 20 women with clinical/genetic FH and 63 healthy women with nChol were included - details are presented in the figures. Participants had to have a regular cycle between 21-35 days, while pregnant women, and those using hormone-based contraceptives without hormone free interval (HFI) were excluded. Lipid levels were measured in the follicular (visit 1), ovulation (visit 2), and luteal (visit 3) phases. In women using oral contraceptives (OC) measurements were taken during day 12-14 of the pill period (visit 1) and during day 5-7 of the HFI (visit 2). Results: Mean (sd) age of the included subjects was 33 (9) years, BMI 23.9 (4) kg/m2, and cycle duration 28 (2) days. These characteristics were similar in FH and nChol. Women with nChol showed slight, although statistically significant, cycle-related variations in cholesterol levels (mean maximum variation total Chol 0.53, LDL-Chol 0.39 and HDL-Chol 0.22 mmol/L; figure 1). FH women who did not receive statin therapy for various reasons showed largest mean variations (total Chol 0.80, LDL-Chol 0.59 and HDL-Chol 0.23 mmol/L), with the highest lipid levels during the ovulation phase. The women with OC had an increase in total- and LDL-cholesterol (groups combined: mean difference 0.55 and 0.51 mmol/L, respectively) between the two visits (n=9) (figure 2). Conclusions: In women with untreated FH and normal cholesterol with a regular menstrual cycle, total- and HDL-cholesterol were highest at ovulation. These menstrual fluctuations were absent in women with FH who used statins. Women with OC showed an increase in total- and LDL-cholesterol from the contraceptive pill period to the HFI. Even though in most women the absolute variation in lipid levels during the menstrual cycle and OC are modest, the moment of measurement can be of clinical value in particular in women with untreated high lipid levels. In these women, it is recommended to measure lipid levels at a fixed time of the menstrual cycle.Figure 1Figure 2