Sub theme 1.2
Regulation of calcium and bone metabolism

Goals of research: general outline
Scientific achievements
Future plans: special goals and approach
Running projects
Associated staff

Workgroup leaders   Department
dr.  J.P.T.M.  van  Leeuwen   Internal Medicine
PhD  E.L.  Lubberts   Rheumatology

Goals of research: general outline

The focus of this research program is on skeletal and calcium homeostasis and development and progression of related disorders with particular emphasis on aging. Increasing life span is accompanied by an increase in age-related diseases. In particular, osteoporosis (OP) and osteoarthritis (OA) affect the locomotor system and greatly limit mobility at advanced ages. Both OP and OA are important common age-related diseases with a large impact on quality of life as well as health care budget.

Development of pharmaceutical and life style interventions as prevention or as treatment is important and requires an optimal knowledge in aetiology and mechanisms of development of disease. Genetic and genomic studies can help to identify the genes and biological pathways involved, and thereby improve biological understanding of the disease process. Such studies can identify biological markers for (early) diagnostics and also allow for the development of novel, potentially therapeutic interventions.

Current therapies for OP are directed to inhibit bone loss and thereby its progression. However, because bone loss has already occurred when the consequences of OP have become overt this is not an optimal treatment. Thus, there is a major need for anabolic therapies, which stimulate bone formation and thereby improve bone health. Similarly, for OA no (optimal) therapies are available and the existing treatments are focussed on pain reduction and/or joint replacement. While OP and OA share some common biological and disease pathways and share target tissues, both are studied in this program. Traditionally this has been focussed on OP while OA research is more recent.

The department of Internal Medicine has collaborating combinations of molecular, genetic, cellular, animal, epidemiological and clinical studies on calcium and bone metabolism. It is our vision that not these individual approaches but that the combination of these approaches and integration of data sets is the key to success. Bio-informatic and systems biological analyses of gene, protein and enzyme activity profiles to characterise bone cell differentiation, -formation and -degradation using human bone cell models. This includes development of medium/high throughput screenings procedures to identify therapeutic targets and to evaluate novel therapeutic compounds. Calcium homeostasis and skeletal metabolism is also studied in relation to ageing by analyses of experimental animal models, e.g. premature ageing mice.

Scientific achievements

Molecular Cell Biological Research

Firstly, osteoblasts, the bone forming cells, play a pivotal role in bone metabolism by forming bone and controlling bone resorption by osteoclasts. In the clinic the therapies for osteoporosis are directed to inhibit bone resorption (i.e. inhibition of further bone loss). No potent bone anabolic therapies are available. We focussed on identifying bone anabolic therapeutic targets as well as novel diagnostic markers (paralleling the genetic approaches). For this we characterized a human osteoblast-based bone formation model as well as set up human mesenchymal stem cell studies (osteoblasts are derived from mesenchymal stem cells). We performed extensive gene expression profiling and protein profiling of these cell models against the backdrop of the osteoblast differentiation and bone formation. Within a EU program and a NWO funded TOP grant we focus to develop systems biological approaches to explain osteoblast differentiation and bone formation.

The expression profiling studies and perturbation studies with growth factors lead to a first identification of follistatin as a bone anabolic target. This finding and the identified changes in extracellular matrix gene expression in relation to mineralization led to patent applications and the founding of a spin off company: Therosteon. Currently there is a short list of drug/diagnostic target candidates that is further functionally screened and approaches are developed to merge the expression profiling data with the genome wide association data (see part B.)

Secondly, calcium homeostasis in relation to aging is studied at population level in the Rotterdam study and at animal level. Together with the Department of Physiology (Prof. Bindels) of the university of Nijmegen we were able to demonstrate a crucial role for the calcium channel TRPV5 in maintaining calcium homeostasis in which bone plays a prominent role. More recently we demonstrated that TPRV5 is also expressed in osteoclast and is involved in bone resorption. Currently studies (at cellular and transgenic animal level) are ongoing to identify the role of TPRV6 (like TRPV5 calcium specific) and TRPV4 (a non-calcium specific channel). Both are expressed in osteoblasts as well as osteoblasts. These studies will contribute to the knowledge of the role of these channels in bone metabolism and may provide clues for intervention.

Thirdly, together with the Genetics Department (Prof. Hoeijmakers and Prof. van der Horst) the skeletal phenotype and mesenchymal stem cell behaviour with aging as been investigated in DNA repair impaired transgenic animals (TTD mice). These animals show a normal skeletal development up to 39 weeks of age but after that demonstrate and strongly accelerated skeletal aging, which is preceded by a drop in mesenchymal stem cells. These studies demonstrated the significance of proper DNA repair for healthy aging. These data have been a strong support for DNage (biotech spin off by Prof. Hoeijmakers). This has led together with DNage to an European grant together with a Spanish company to develop a zebra fish based screening system of therapeutic and diagnostic candidates.

Future plans: special goals and approach

Current molecular cell biological work and aging studies will be taken forward. In addition gene and protein profiles will be combined by intersection analyses in relation to the phenotypic expression (i.e. bone formation). This way identified genes will be combined with GWAS data an functionally analysed for their impact on bone formation and used for potential drug development.  Focus of research will also be to apply systems biology approaches to model the development of stem cells with the aim to be able to better understand and control stem cell renewal, lineage commitment and differentiation.

In collaboration with Department of Hematology (Prof. J. Cornelissen) a research line will be developed to study the osteoblast stem cell niche. The aim is a.o. to be improve cord blood usage for bone marrow transplantation.

Together with the department of Rheumatology studies will be performed on vitamin D control of immune cell function and the interaction between immune cells, osteoclasts and osteoblasts.

Recent development is the setup of protein profiling as well as serum miRNA profiling of women with or without osteoporosis (low bone mass and fractures). The analyses are currently ongoing has been set up and these analyses are on going. The focus is identifying osteoporosis specific markers, which will be linked to the genetic studies. In addition, osteoclasts have been cultured from peripheral blood of these women and are used for functional comparison.

Most recent publications

1.      M Eijken, S Swagemakers, M Koedam, C Steenbergen, P Derkx, AG Uitterlinden, PJ van der Spek, JA Visser, FH de Jong, HA Pols, JPTM van Leeuwen. (2007) The activin A-follistatin system: potent regulator of human extracellular matrix mineralization. FASEB J. 2007 21(11):2949-60. IF:  6.79

2.      M van Driel, M Koedam, CJ Buurman, M Hewison, H Chiba, AG Uitterlinden, HAP Pols, JPTM van Leeuwen (2006) Evidence for auto/paracrine actions of vitamin D in bone: 1α-hydroxylase expression and activity in human bone cells. FASEB J Express, 20(13):2417-2419. IF: 6.79

3.      M.Eijken, M. Hewison, M.S. Cooper, FH de Jong, H Chiba, PM Stewart, AG Uitterlinden, HAP Pols, JPTM van Leeuwen. (2005) 11β-Hydroxysteroid dehydrogenase expression and glucocorticoid synthesis are directed by a molecular switch during osteoblast differentiation. Mol Endocrinology 19(3):621-631. IF 5.34

4.      BC van der Eerden, JG Hoenderop, TJ de Vries, T Schoenmaker, CJ Buurman, AG Uitterlinden, HAP Pols, RJ Bindels, JPTM van Leeuwen. (2005) The epithelial Ca2+ channel TRPV5 is essential for proper osteoclastic bone resorption. Proc Natl Acad Sci U S A.; 102(48):17507-17512. IF: 9.6

5.      JG Hoenderop, JPTM van Leeuwen, BC van der Eerden, FF Kersten, van der Kemp AW, Merillat AM, Waarsing JH, Rossier BC, Vallon V, Hummler E, Bindels RJ (2003) Renal Ca2+ wasting, hyperabsorption, and reduced bone thickness in mice lacking TRPV5. J Clin Invest 112(12):1906-1914. IF :16.92

People associated with sub theme 1.2: Regulation of calcium and bone metabolism
Name Position Department
Dr.  E.  Ahmad PhD-candidate Endocrinology
Ladyofrage  AlexglidE PhD-candidate General Surgery
drs.  R.  Alves PhD-candidate Internal Medicine
M.  Baroncelli PhD-candidate Internal Medicine
Dr.  Y.M.  Bastiaansen-Jenniskens Assistent professor (UD) Orthopaedics
MD  J.W.  van den  Berg PhD-candidate Immunology
L.  van den  Berk Other as mentioned (please specify in remarks) Internal Medicine
Paulpeter  BerryTen Senior researcher not being a workgroup leader General Surgery
drs  A  Bosman PhD-candidate Internal Medicine
drs.  S.M.  Botter PhD-candidate Internal Medicine
C.  Bruedigam PhD-candidate Internal Medicine
MSc  A.M.  Brum PhD-candidate Internal Medicine
drs.  G.M.  van  Buul PhD-candidate Orthopaedics
C.J.  Buurman Technician Lung Diseases
J.C  Chen PhD-candidate Internal Medicine
S.C.  Clockaerts PhD-candidate Orthopaedics
Tmmaverick  DentalHah Senior researcher not being a workgroup leader General Surgery
Ms  SBD  Dlamini PhD-candidate Internal Medicine
K.D.  Drabek Postdoc/junior researcher Internal Medicine
Dr.  M.  van  Driel Senior researcher not being a workgroup leader Internal Medicine
Drs.  R.R.  Dulfer PhD-candidate Surgery
Dr.  C.J.  van der  Eerden Senior researcher not being a workgroup leader Internal Medicine
dr.  M.  Eijken Postdoc/junior researcher
Dr.  E.  Elesaid PhD-candidate Endocrinology
drs  J.A.M.  Emons PhD-candidate Pediatrics Endocrinology
MSc  A.W.  Enneman PhD-candidate Internal Medicine
dr.  Y.  Fang Postdoc/junior researcher Clinical Genetics
C.F.  Feijt Technician Orthopaedics
Tmmaverick  FusMixail Physician (MD) General Surgery
за&  Thun  GlennApoli Senior researcher not being a workgroup leader General Surgery
Dr.  I.  Gussekloo Senior researcher not being a workgroup leader
MSc  M.F.P.  de  Haas PhD-candidate Orthopaedics
Ing.  W.  Hugens Technician Internal Medicine
Dr.  H.  Jahr Senior researcher not being a workgroup leader  Smooveb73  Karen Sun Technician General Surgery
K.J.G  Kenswil PhD-candidate Hematology
CMJ  van  Kinschot PhD-candidate Endocrinology
MSc  JAZ  Klazen PhD-candidate Internal Medicine
S.C.E.  Klein Nagelvoort - Schuit Physician (MD)
Ing.  M.  Koedam Technician Endocrinology
drs.  W.N.H.  Koek PhD-candidate Internal Medicine
J.L.M.  Koevoet Technician Orthopaedics
N.  Kops Technician Orthopaedics
Dr.  JJCM  Kruse Other as mentioned (please specify in remarks) Research and Development
Dr.  JJCM  Kruse Other as mentioned (please specify in remarks) Research and Development
Mr.  S.K.D.  Kumar Postdoc/junior researcher Bio Science
Mr  P  Mr  Kumar PhD-candidate Internal Medicine
drs  DM  van de  Laarschot PhD-candidate Endocrinology
dr.  J.P.T.M.  van  Leeuwen Workgroup leader within the School Internal Medicine
j.  Lenstra PhD-candidate Anaesthesiology
drs.  H.J.  van  Loenen
PhD  E.L.  Lubberts Workgroup leader within the School Rheumatology
dr.  A.  van  Marle
MSc  M.L.  van  Melle PhD-candidate Orthopaedics
D.M.N.  Mendes PhD-candidate Pediatrics Oncology
R.L.  Miclea PhD-candidate Pediatrics Endocrinology
J.  Morhayim PhD-candidate Internal Medicine
Dr.  C.  Nicolaije PhD-candidate Internal Medicine
MD, MA  H.L.D.W.  Oei PhD-candidate Internal Medicine
drs.  E.A.  Ooms PhD-candidate Obstetrics and Gynaecology
MSc  S.M.J.  Paulissen PhD-candidate Rheumatology
MJ  Peters PhD-candidate Internal Medicine
пенобетон  Tmmaverick  Phillipvah Other as mentioned (please specify in remarks) General Surgery
Prof.dr.  H.A.P.  Pols Other as mentioned (please specify in remarks)
drs  J.S  Renes PhD-candidate Pediatrics Endocrinology
drs  F.  Rivadeneira PhD-candidate
I.J.  Robbesom - van den Berge Technician Internal Medicine  Paulpeter  RobertMen MSc student (please specify in remarks) General Surgery
Drs.  M.J.  Sandker PhD-candidate Orthopaedics
-  QettoE  SEOmab Professor not being a workgroup leader General Surgery
пенобетон  Paulpeter  SheltonPar PhD-candidate General Surgery  MB  Snijder Postdoc/junior researcher Epidemiology  S.P.R.  Tillemans PhD-candidate Rheumatology
Dr.  M.  van der  Velde Postdoc/junior researcher Internal Medicine
Dr.  N.  van der   Velde Postdoc/junior researcher Internal Medicine
drs  M.  van der  Velde PhD-candidate Endocrinology
DBJ  Vermeulen MSc student (please specify in remarks) Endocrinology
T.P.C.  de  Vet Other as mentioned (please specify in remarks) Internal Medicine
K  Waqas PhD-candidate Endocrinology
PhD  H.  Weinans Assistent professor (UD) Orthopaedics
M.A.   Wesdorp PhD-candidate Orthopaedics
mining dogecoin  Boogieq  WilliamEroff Professor not being a workgroup leader General Surgery
Drs.  M.L.  te  Winkel PhD-candidate Pediatrics Oncology
V.J.  Wckel PhD-candidate Internal Medicine
MD  J.L.  Yin PhD-candidate Internal Medicine