Targeting cholesterol excretion. Lily Jakulj, MD

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1 Center of Liver, Digestive and Metabolic Diseases Dept of Vascular Medicine Targeting cholesterol excretion Lily Jakulj, MD

2 Reverse cholesterol transport BS PL CH CH BS, neutral sterols

3 1. Plasma HDL-c determines RCT BS PL CH CH BS, neutral sterols

4 2. Obligate role of bile in RCT BS PL CH CH BS, neutral sterols

5 1. Plasma HDL-c and RCT Biliary and fecal cholesterol excretion not impaired in ABCA1-/- mice 1,2 rhdl increased plasma HDL-c and centripetal flux to the liver, but not FSE in ABCA1-/- mice 3 Upregulation of individual steps in RCT did not affect FSE in normolipidemic mice 4 Human FSE studies conflicting 1. Groen, JCI Xie, JLR Jolley, JLR Alam, JBC 2001

6 Tissue cholesterol efflux (mg/kg/hr) Impaired in vivo tissue cholesterol efflux in subjects with genetically low HDL-c 6 p = * * APOA1 or ABCA1 def. n=7 controls n = 6 mean HDL-c: mean HDL-c: 0.33 mmol/l (SD 0.34) 1.42 mmol/l (SD 0.28) Holleboom, Jakulj, Groen, Stroes, unpublished

7 Fecal excretion (mg/day) FSE is equal in low HDL-carriers and controls Carriers Controls neutral sterols bile acids Holleboom, Jakulj, Groen, Stroes, unpublished

8 1. Plasma HDL-c determines RCT Plasma HDL-c does not adequately reflect RCT in mice and humans with isolated low HDL-c Despite impaired TCE in carriers of mutations in APOA1 or ABCA1, compensating mechanisms exist Fecal sterol excretion, the obligate endpoint of RCT may depend on alternative (non-hdl?) pathways

9 2. Obligate role of bile in RCT BS PL CH CH BS, neutral sterols Yu, PNAS 2002

10 Non-biliary cholesterol excretion Increased FNS loss in dogs with complete biliary diversion and cholesterol free diet (Pertsemlidis, JCI 1973) Genetically modified mice with impaired biliary secretion: C7a hydroxylase -/- (Schwarz, JLR 1998) Abcb4-/- (Kruit, Gastroenterology 2005) Hepatic NPC1L1 +++ (Temel, JCI 2007) Hepatic ACAT2 -/- (Brown, JBC 2008)

11 NPC1L1 Liver-Tg mice > 90% reduction of biliary cholesterol secretion Normal FNS excretion Normal intestinal cholesterol absorption Similar plasma cholesterol levels as in wildtype Temel, JCI 2007

12 Intestinal perfusion experiments perfusion inflow 3ml/h + /- TC/PC mixed micelles 90-min perfusate collection 1x/15min Bile cannulation 14 C injection in tail vein Van der Velde, Groen, Gastroenterology 2007

13 µmol/day.100g body weight Trans-intestinal cholesterol excretion proximal medial distal Van der Velde & Groen, Gastroenterology 2007

14 In vivo stable isotope study Quantification of fractional and absolute contributions to FNS loss in vivo in mice +/ LXR agonist van der Veen, Groen, JBC 2009

15 LXR-induced increase in FNS loss is largely due to TICE stimulation van der Veen, Groen, JBC 2009

16 Stimulation of TICE in mouse models Liver HDL LDL Plasma TICE + 1. Lumenal acceptors (PL) 2. High Fat Diet (fatty acids) 3. PPARδ agonist Bile 4. LXR agonist Absorption Diet Feces Shedding/Synthesis 1. Van der Velde, Groen, Gastroenterology Van der Velde, Groen, Am J Physiol Gastrointest Liver Physiol Vrins, Groen, JLR van der Veen, Groen, JBC 2009

17 Is TICE an anti-atherogenic mechanism? BS PL CH CH BS, neutral sterols

18 Macrophage-specific RCT assay degoma, JACC 2008

19 Non-biliary Φ-RCT in liver-npc1l1++ mice BS PL CH CH 3 H-chol BS, neutral sterols 3 H-chol + Temel, Cell Metabolism 2010

20 Obligate biliary Φ-RCT in Abcb4 -/- mice BS PL CH CH 3 H-chol BS, neutral sterols 3 H-chol - Nijstad, Gastroenterology 2011

21 Underlying mechanisms? Van der Velde, World J Gastroenterol 2010 Van der Velde, Brufau, Groen, Curr Opin Lipidol 2008

22 TICE in humans? Fecal sterols of non-dietary origin present in patients with complete biliary obstruction 1 Bile diversion in hofh patients produced a 6-8-fold increase in GI sterol output 2 Human intestinal perfusion studies: TICE estimated as ~44% of total FNS loss 3 1 Cheng, Proc Soc Exp Biol Med Deckelbaum, NEJM Simmonds, JCI 1967

23 Human TICE studies Proof-of-concept in patients with total biliary obstruction In vivo stable isotope study in subjects with intact enterohepatic cycle

24 Proof-of-concept: bile-diverted subjects Liver HDL LDL Plasma 50mg 13 C-chol Bile TICE Bile Absorption Diet Feces Shedding/Synthesis 13 C-chol

25 Human in vivo stable isotope study Male subjects, n 15 Age, years 61.7 ± 3.4 BMI, kg/m ± 2.5 Total cholesterol, mmol/l 5.59 ± 0.65 LDL-cholesterol, mmol/l 3.74 ± 0.50 HDL-cholesterol, mmol/l 1.32 ± 0.27 Triglycerides, mmol/l 1.01 [ ] Jakulj, Stroes, Groen, unpublished

26 Human in vivo flux study i.v. 13 C 2 cholesterol 50 mg oral D 7 cholesterol 50 mg * ** *** Blood (fasting) Blood (post-prandial) Bile * * * * * * ** *** ** ** oral D 4 - CA and D 4 - CDCA 50 mg feces feces feces feces feces feces feces feces feces - 48 oral D 4 sitostanol 3 mg t.i.d.

27 FNS excretion (gram/day) TICE ± 30% of FNS loss in humans 1,6 1,4 1,2 1,0 shedding TICE Bile derived 0,8 Non-absorbed 0,6 0,4 0,2 0,0 Jakulj, Stroes, Groen, unpublished

28 2. Obligate role of bile in RCT Non-biliary cholesterol excretion contributes to plasma cholesterol elimination in mice and men TICE might serve as an attractive target to improve RCT Focus on underlying molecular mechanisms and possibilities to stimulate TICE in humans

29 Acknowledgements A.K. Groen T.H. van Dijk T. Boer R. Boverhof F. Stellaard G. Brufau E.S.G. Stroes A.G. Holleboom R. Franssen K.P. van Lienden E.A.J. Rauws K.A.C. Booij / D.J. Gouma