Protein arginine methyltransferase 3 (PRMT3) is a co-activator of liver X receptor capable of selectively modulating hepatic triglyceride synthesis. Here we investigated whether pharmacological... Show moreProtein arginine methyltransferase 3 (PRMT3) is a co-activator of liver X receptor capable of selectively modulating hepatic triglyceride synthesis. Here we investigated whether pharmacological PRMT3 inhibition can diminish the hepatic steatosis extent and lower plasma lipid levels and atherosclerosis susceptibility. Hereto, male hyperlipidemic low-density lipoprotein receptor knockout mice were fed an atherogenic Western-type diet and injected 3 times per week intraperitoneally with PRMT3 inhibitor SGC707 or solvent control. Three weeks into the study, SGC707-treated mice developed severe pruritus and scratching-associated skin lesions, leading to early study termination. SGC707-treated mice exhibited 50% lower liver triglyceride stores as well as 32% lower plasma triglyceride levels. Atherosclerotic lesions were virtually absent in all experimental mice. Plasma metabolite analysis revealed that levels of taurine-conjugated bile acids were ~ threefold increased (P < 0.001) in response to SGC707 treatment, which was paralleled by systemically higher bile acid receptor TGR5 signalling. In conclusion, we have shown that SGC707 treatment reduces hepatic steatosis and plasma triglyceride levels and induces pruritus in Western-type diet-fed LDL receptor knockout mice. These findings suggest that pharmacological PRMT3 inhibition can serve as therapeutic approach to treat non-alcoholic fatty liver disease and dyslipidemia/atherosclerosis, when unwanted effects on cholesterol and bile acid metabolism can be effectively tackled. Show less
The research described in this thesis shows that hypercholesterolemia, a well-established risk factor for atherosclerosis, can impact skin lipid pool and barrier function already at young age. In... Show moreThe research described in this thesis shows that hypercholesterolemia, a well-established risk factor for atherosclerosis, can impact skin lipid pool and barrier function already at young age. In the field of atherosclerosis, we showed that the small peptide Lyp-1 can be used as a targeting molecule in liposomal formulations to deliver liver X receptor agonist to plaque resident foam cells/lipid-rich macrophages. Elucidation of the mechanisms underlying the intercommunication between plasma lipids and skin lipids may also bring valuable opportunities to prevent and treat dermatological pathologies in dyslipidemic patients; perhaps in combination with anti-atherogenic therapies. Thus, by deepening our knowledge we may improve our advice to the patients and ultimately improve their quality of life. Show less
Atherosclerosis is characterized by the retention of lipids in foam cells in the arterial intima. The liver X receptor (LXR) agonist GW3965 is a promising therapeutic compound, since it induces... Show moreAtherosclerosis is characterized by the retention of lipids in foam cells in the arterial intima. The liver X receptor (LXR) agonist GW3965 is a promising therapeutic compound, since it induces reverse cholesterol transport in foam cells. However, hepatic LXR activation increases plasma and liver lipid levels, inhibiting its clinical development. Herein, a formulation that specifically enhances GW3965 deposition in the atherosclerotic lesion is aimed to be developed. GW3965 is encapsulated in liposomes functionalized with the cyclic peptide Lyp-1 (CGNKRTRGC), which binds the p32 receptor expressed on foam cells. These liposomes show preferential uptake by foam cells in vitro and higher accumulation in atherosclerotic plaques in mice compared to non-targeted liposomes as determined by in vivo imaging. Flow cytometry analysis of plaques reveals increased retention of Lyp-1 liposomes in atherosclerotic plaque macrophages compared to controls (p < 0.05). Long term treatment of established plaques in LDLR -/- mice with GW3965-containing Lyp-1 liposomes significantly reduces plaque macrophage content by 50% (p < 0.01). Importantly, GW3965-containing Lyp-1 liposomes do not increase plasma or hepatic lipid content. Thus, GW3965-containing Lyp-1 liposomes successfully target the atherosclerotic macrophages allowing plaque stabilization without commonly observed side effects of LXR agonists. Show less
Martins Cardoso, R.; Creemers, E.; Absalah, S.; Hoekstra, M.; Gooris, G.S.; Bouwstra, J.A.; Eck, M. van 2019
Scavenger receptor class B type I (SR-BI) mediates the selective uptake of cholesteryl esters (CE) from high-density lipoproteins (HDL). An impaired SR-BI function leads to... Show moreScavenger receptor class B type I (SR-BI) mediates the selective uptake of cholesteryl esters (CE) from high-density lipoproteins (HDL). An impaired SR-BI function leads to hyperalphalipoproteinemia with elevated levels of cholesterol transported in the HDL fraction. Accumulation of cholesterol in apolipoprotein B (apoB)-containing lipoproteins has been shown to alter skin lipid composition and barrier function in mice. To investigate whether these hypercholesterolemic effects on the skin also occur in hyperalphalipoproteinemia, we compared skins of wild-type and SR-BI knockout (SR-BI−/−) mice. SR-BI deficiency did not affect the epidermal cholesterol content and induced only minor changes in the ceramide subclasses. The epidermal free fatty acid (FFA) pool was, however, enriched in short and unsaturated chains. Plasma CE levels strongly correlated with epidermal FFA C18:1 content. The increase in epidermal FFA coincided with downregulation of cholesterol and FFA synthesis genes, suggesting a compensatory response to increased flux of plasma cholesterol and FFAs into the skin. Importantly, the SR-BI−/− epidermal lipid barrier showed increased permeability to ethyl-paraminobenzoic acid, indicating an impairment of the barrier function. In conclusion, increased HDL-cholesterol levels in SR-BI−/− mice can alter the epidermal lipid composition and lipid barrier function similarly as observed in hypercholesterolemia due to elevated levels of apoB-containing lipoproteins. Show less
Madsen, M.; Hansen, P.R.; Nielsen, L.B.; Martins Cardoso, R.; Eck, M. van.; Pedersen, T.X. 2018
