TY  - JOUR
A1  - Boschert, V.
A1  - Frisch, C.
A1  - Back, J. W.
A1  - van Pee,, K.
A1  - Weidauer, S. E.
A1  - Muth, E.-M.
A1  - Schmieder, P.
A1  - Beerbaum, M.
A1  - Knappik, A.
A1  - Timmerman, P.
A1  - Mueller, T. D.
T1  - The sclerostin-neutralizing antibody AbD09097 recognizes an epitope adjacent to sclerostin's binding site for the Wnt co-receptor LRP6
JF  - Open Biology
N2  - The glycoprotein sclerostin has been identified as a negative regulator of bone growth. It exerts its function by interacting with the Wnt co-receptor LRP5/6, blocks the binding of Wnt factors and thereby inhibits Wnt signalling. Neutralizing anti-sclerostin antibodies are able to restore Wnt activity and enhance bone growth thereby presenting a new osteoanabolic therapy approach for diseases such as osteoporosis. We have generated various Fab antibodies against human and murine sclerostin using a phage display set-up. Biochemical analyses have identified one Fab developed against murine sclerostin, AbD09097 that efficiently neutralizes sclerostin's Wnt inhibitory activity. In vitro interaction analysis using sclerostin variants revealed that this neutralizing Fab binds to sclerostin's flexible second loop, which has been shown to harbour the LRP5/6 binding motif. Affinity maturation was then applied to AbD09097, providing a set of improved neutralizing Fab antibodies which particularly bind human sclerostin with enhanced affinity. Determining the crystal structure of AbD09097 provides first insights into how this antibody might recognize and neutralize sclerostin. Together with the structure–function relationship derived from affinity maturation these new data will foster the rational design of new and highly efficient anti-sclerostin antibodies for the therapy of bone loss diseases such as osteoporosis.
KW  - phage display
KW  - Wnt signalling
KW  - sclerostin
KW  - neutralizing antibody
KW  - osteoporosis
Y1  - 2016
U6  - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bvb:20-opus-177925
VL  - 6
ER  - 
TY  - JOUR
A1  - Brandenburg, Vincent M.
A1  - Kramann, Rafael
A1  - Koos, Ralf
A1  - Krueger, Thilo
A1  - Schurgers, Leon
A1  - Mühlenbruch, Georg
A1  - Hübner, Sinah
A1  - Gladziwa, Ulrich
A1  - Drechler, Christiane
A1  - Ketteler, Markus
T1  - Relationship between sclerostin and cardiovascular calcification in hemodialysis patients: a cross-sectional study
JF  - BMC Nephrology
N2  - Background: Sclerostin is a Wnt pathway antagonist regulating osteoblast activity and bone turnover. Here, we assessed the potential association of sclerostin with the development of coronary artery (CAC) and aortic valve calcifications (AVC) in haemodialysis (HD) patients. Methods: We conducted a cross-sectional multi-slice computed tomography (MS-CT) scanning study in 67 chronic HD patients (59.4 +/- 14.8 yrs) for measurement of CAC and AVC. We tested established biomarkers as well as serum sclerostin (ELISA) regarding their association to the presence of calcification. Fifty-four adults without relevant renal disease served as controls for serum sclerostin levels. Additionally, sclerostin expression in explanted aortic valves from 15 dialysis patients was analysed ex vivo by immunohistochemistry and mRNA quantification (Qt-RT-PCR). Results: CAC (Agatston score > 100) and any AVC were present in 65% and in 40% of the MS-CT patient group, respectively. Serum sclerostin levels (1.53 +/- 0.81 vs 0.76 +/- 0.31 ng/mL, p < 0.001) were significantly elevated in HD compared to controls and more so in HD patients with AVC versus those without AVC (1.78 +/- 0.84 vs 1.35 +/- 0.73 ng/mL, p = 0.02). Multivariable regression analysis for AVC revealed significant associations with higher serum sclerostin. Ex vivo analysis of uraemic calcified aortic valves (n = 10) revealed a strong sclerostin expression very close to calcified regions (no sclerostin staining in non-calcified valves). Correspondingly, we observed a highly significant upregulation of sclerostin mRNA in calcified valves compared to non-calcified control valves. Conclusion: We found a strong association of sclerostin with calcifying aortic heart valve disease in haemodialysis patients. Sclerostin is locally produced in aortic valve tissue adjacent to areas of calcification.
KW  - coronary calcification
KW  - cardiovascular disease
KW  - aortic valve disease
KW  - calcium
KW  - mortality
KW  - sclerostin
KW  - aortic valve
KW  - bone formation
KW  - computed tomography
KW  - fetuin A
KW  - risk factors
KW  - GLA protein UCMGP
KW  - kidney-disease CKD
KW  - coronary-artery calcification
KW  - hemodialysis
KW  - mineral metabolism
KW  - vascular calcification
KW  - renal osteodystrophy
Y1  - 2013
U6  - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bvb:20-opus-122070
SN  - 1471-2369
VL  - 14
IS  - 219
ER  -